Today, the presence of recalcitrant pollutants in wastewater, such as pharmaceuticals or other organic compounds, is one of the main obstacles to the widespread implementation of water reuse. In this context, the development of innovative processes for their removal becomes necessary to guarantee effluent quality. This work presents the potentiality of magnetic nanoparticles immobilized on SBA-15 mesoporous silica as Fenton and photo-Fenton catalysts under visible light irradiation. The influence of the characteristics of the compounds and nanoparticles on the removal yield was investigated. Once the key aspects of the reaction mechanism were analyzed, to evaluate the feasibility of this process, an azo dye (Orange II) and an antibiotic (sulfamethoxazole) were selected as main target compounds. The concentration of Orange II decreased below the detection limit after two hours of reaction, with mineralization values of 60%. In addition, repeated sequential experiments revealed the recoverability and stability of the nanoparticles in a small-scale reactor. The benchmarking of the obtained results showed a significant improvement of the process using visible light in terms of kinetic performance, comparing the results to the Fenton process conducted at dark. Reusability, yield and easy separation of the catalyst are its main advantages for the industrial application of this process. Freshwater is one of the most valuable resources of a territory, due to its essential role in life. Its consumption is closely influenced by climatic and anthropogenic factors . PopulatWWTPs are the main alternative to prevent contamination of freshwater and groundwater. Beyond the removal of organic matter, nutrients and suspended solids, the most recalcitrant compounds present in the water, known as emerging contaminants, can bypass these treatments and reach the effluents. For this reason, some types of tertiary treatments are being studied in recent years in the field of WWTPs to remove these compounds, in order to limit or prevent their release into the environment . Dependi2O2, UV light or catalysts such as transition metals (Cu(II), Fe(II), ZnO(II), …) or metal oxides  [In these processes, highly oxidative compounds such as ozone or hydrogen peroxide are used to generate radicals such as·OH to achieve satisfactory removal efficiencies. In the case of ozone-based processes, removal rates above 90% can be achieved for PPCPs , the maie2O3, …) ,14. Althe2O3, …) . In this2 and ZnO) that generate an electro-hole pair when irradiated by a suitable light source, causing the promotion of electrons from the valence band to the conduction band [2+ as catalyst to enhance the oxidation potential of H2O2 under acidic conditions (around pH 3) [2− and singlet oxygen (1O2) can be produced during the reactions [On the one hand, semiconductor photocatalysis is based on the use of certain metal oxides   (Equatioeactions .(1)Fe2+3+ to Fe2+ is favoured (Equation (3)), positively affecting the kinetics. Further research based on this reaction and applied to the field of wastewater treatment focused on the study and development of innovative catalysts to improve separation, removal rates or shift of reaction conditions towards circumneutral pH [2. Some authors have studied the stabilization of these species using iron complexing agents [With the use of light sources, the equilibrium reaction for the regeneration of catalyst from Feutral pH . The maig agents ,30 or chg agents , but in g agents . Neverthg agents . Substitg agents . At thisg agents ,33. Howeg agents .However, the changes in the surface charge affect the interaction between nanoparticles and target compounds, and for this reason, supporting the nanoparticles on mesoporous silica (SBA-15) increases the specific surface improving the kinetics. Nevertheless, the bottleneck of the Fenton reaction is the regeneration of the catalysts. The incorporation of a light source allows the formation of new reaction routes to regenerate Fe(III), while direct photolysis of hydrogen peroxide occurs. Both changes in the reaction pathways lead to increased reaction rates . DiffereIn this research work, the photo-Fenton process was studied, comparing the results obtained with the conventional Fenton process under the same conditions. Different target compounds and types of nanoparticles were analysed, selecting those that showed the best results. In addition, the optimization of the selected variables  was investigated using response surface methodology. Finally, the performance of the selected nanoparticles was evaluated under the best conditions in a 2 L reactor for the removal of Orange II (OII) and sulfamethoxazole (SMX), analysing the reuse of the nanoparticles, kinetic performance, degree of mineralisation and effluent toxicity. The use of visible light together with magnetic separation brings this process closer to an industrial application. The replacement of ultraviolet lights with more efficient ones allows reducing operating costs. Moreover, the use of magnetic fields to separate the catalyst improves the process by avoiding the use of a catalyst recovery unit.3·6H2O, 97% w/w), tetraethyl orthosilicate , polyethyleneimine , polyacrylic acid , triblock copolymer Pluronic P123 (PEO20-PPO70-PEO20), hydrochloric acid , isopropyl alcohol  and hydrogen peroxide  were purchased from Sigma Aldrich . Iron (II) sulphate heptahydrate , ammonium hydroxide , tetramethylammonium hydroxide , orthophosphoric acid  and acetonitrile  were purchased from Fluka . Sodium hydroxide  was purchased from Panreac Química SLU . Moreover, the reagents used as target compounds and their details are shown in Iron (III) chloride hexahydrate  was added to the mixture and the solution was incubated for 1 h at 60 °C. Once the reaction is over, deionized water was used to wash the synthesized nanoparticles three times and withdrawn by applying an external magnetic field. Finally, a TMAOH solution was used to reach pH 10 and stabilize the nanoparticles in solution [The synthesis of sterically stabilized black magnetite was conducted following the Massart’s method . For thisolution . Polymersolution .3PO4 and TEOS. The obtained product was dried, and several washing cycles were performed with organic solvents to remove the remaining chemicals in order to reduce the adsorption of compounds that could negatively affect the catalytic performance. Furthermore, the synthesis of the immobilized magnetite on mesoporous silica was done by incorporating the SBA-15 matrix into the magnetite synthesis procedure when the iron salts are added [On the other hand, the synthesis of magnetite supported by SBA-15 mesoporous silica was based on the Colilla method , using are added .2 adsorption-desorption isotherms obtained using a Quantachrome Autosorb IQ2 instrument. The ζ−potential was measured by laser-Doppler anemometry in diluted samples . The nanoparticle concentration of stocks was obtained by thermogravimetric analysis (TGA), and the thermogravimetric curves were recorded using a Perkin Elmer TGA 7 thermobalance , operating under nitrogen atmosphere, from room temperature to 850 °C, at a scanning rate of 10 °C min−1.The morphological characterization of the nanoparticles was performed using field emission scanning electron microscopy (Zeiss FE-SEM UltraPlus microscope) with the angle-selective backscatter electron detector (AsB detector) . For TEM analysis, a JEOL JEM-1011 transmission electron microscope  was used. The analysis of the crystalline phases was carried out by X-ray diffraction (XRD) on powder samples with a Philips PW1710 diffractometer  . Measurements were taken between 15° < 2θ < 80°, increasing by 0.040° and a time per step of 20 s. Pore size distribution and specific surface area were estimated from N−1. On the other hand, sulfamethoxazole concentration was quantified by a high-performance liquid chromatography with diode array detector instrument (HPLC-DAD), using a Jasco X-LCTM from Jasco Analítica Spain S.L.  with a Gemini® C₁₈ chromatographic column  from Phenomenex Inc. .Both the chemical structure and the absorption wavelength of the target compounds are presented in −2. Moreover, the experiments made under UV-A (365 nm) Pen-Ray® Lamp 11SC-1L  were irradiated with an intensity of 15.68 W m−2. On the other hand, the reactor experiments were made in a methacrylate cylindric 5 L small-scale reactor irradiated by three PL-GL23 fluorescent tubes located around the reactor at the same distance used for 10 mL experiments. After degradation experiments, the nanoparticles were separated from the medium by applying an external magnetic field. The paramagnetic properties of the nanocatalysts allow their complete separation from the effluent enabling their reuse in subsequent cycles. Both for visible and ultraviolet light, the values of irradiance were measured using a PCE-UV34 dosimeter , in the range of 290–390 nm. Control experiments of adsorption, photodegradation, stability against pH and stability against hydrogen peroxide were performed to determine the influence of each parameter on the final degradation of the compounds. Thus, the influence of pH medium, incidence of light and hydrogen peroxide concentration was evaluated. In addition, combinations between two factors such as H2O2 and light were studied. The photodegradation yield (Y) was determined using the following equation (Equation 5):1/2 is the half-life of the compound, and k is the kinetic degradation constant for the given conditions.The photodegradation experiments were made in samples of 10 mL and were irradiated using three 11 W PL-G23 fluorescent tubes (4000 K) purchased from Philips , with an irradiance of 1.08 W mAliivibrio fischeri bioluminescence in a Microtox® M500 purchased from Modern Water . The chemical characterization of the wastewater is shown in To evaluate the effect of the matrix, all the reuse experiments were conducted in a real secondary effluent obtained from a WWTP plant located on Calo-Milladoiro . This treatment plant has been designed for a capacity of 9000 equivalent inhabitants and consists of a primary treatment for the removal of solids and fats, a biological secondary treatment, and a UV-C treatment for the removal of pathogenic microorganisms. Moreover, the anionic and cationic characterization was performed by ion chromatography, using a Metrohm 861 Advanced Compact IC , and the total organic carbon (TOC) was analyzed in Shimadzy TOC 5000 , both equipped with an autosampler. The pH values were measured using a pH-meter GLP 21 of Crison . Toxicity assessment was performed by analyzing In this work, different types of magnetite-based nanoparticles were tested for the degradation of different target compounds using Fenton-based methods. Bare and coated magnetite nanoparticles covered with polymers such as polyacrylic acid (PAA) and polyethyleneimine (PEI) were evaluated. These coatings modify the interaction of nanoparticles with the target compounds  and impr3O4, JCPDS PDF-2 card #19-0629), indicating that the inverse spinel structure is present in the sample. Furthermore, the absence of other peaks reveals that there are no impurities in the samples. No changes in the peaks were observed upon coating with polyacrylic acid (PAA) or polyethyleneimine (PEI), demonstrating that the coating step does not modify the structure. The complete XRD characterization of this type of nanoparticles was described by Fernández et al. [3O4@PAA/SBA15 nanoparticles as prepared and after 1, 5 and 10 reuse cycles. As observed in these nanoparticles, the characteristic peaks of magnetite appear in the XRD pattern, but a higher signal/noise ratio was obtained in the measurements due to the presence of SBA15 mesoporous silica matrix.The characterization of free nanoparticles was performed by X-ray diffractometry (XRD), to analyze the crystallographic structure of magnetite. The main peaks found coincide with the characteristic peaks of polycrystalline magnetite , resulting in −11.452 mV for the Fe3O4@PAA and SBA15/Fe3O4@PEI) was performed using SEM and TEM images. 3O4@PAA/SBA15 nanoparticles, being the complete characterization of the rest of the nanoparticles in Fernández et al. [On the other hand, the morphological characterization of the nanoparticles immobilised on SBA15 mesoporous silica  [−1 with white light irradiation. The results obtained are shown in The non-specific oxidation mechanisms of the Fenton and photo-Fenton processes can oxidize a wide range of chemicals, regardless of the structure of the molecule. In the first step of the evaluation of the oxidative capacity of nanocatalysts, anionic and cationic dyes were used as model compounds: copper phthalocyanine (Cu(II)Pc), methyl green (MG), eriochrome black T (EBT), reactive blue 19 (RB19) and Orange II (OII), whose characteristics and structures are shown in of H2O2) ,33 for a3O4@PAA at pH 3 is −1.468 mV, which explains that the negative surface charge causes electrostatic repulsions with the anionic dyes (OII and RB). The enhanced adsorption of EBT could occur due to the protonation of the azo groups, reducing the partial negative charge of the molecule and aiding adsorption onto the catalyst. The cationic nature of MG was responsible for the partial adsorption of the dye: 59%. The catalyst performance was strongly affected by the interaction between nanoparticles and dyes as a function of the electrostatic charges of the molecules. Compounds that reached high adsorption values such as MG or EBT were similarly removed in the Fenton and photo-Fenton processes, rendering low light irradiation efficiency. This phenomenon was possibly due to the fact that their adsorption on the catalyst surface caused a shielding of the light irradiation and consequently reduced the removal yield.The adsorption control experiments were performed using the same concentration of nanoparticles without the use of light or hydrogen peroxide, and the final concentration was measured after 2 h. For the case of photo-Fenton process, a combined control of hydrogen peroxide and light was conducted, and for the Fenton reaction, this control was performed under dark conditions. In terms of dye removal, OII is the most recalcitrant compound, since it presents the lowest percentage of degradation. To study the contributions of the independent factors in the degradation due to each factor, stability tests were performed. The stability control for pH indicates that no degradation occurred in the tests performed at acidic conditions. Adsorption values were fairly different between the target compounds according to their anionic or cationic nature. The planar structure of Cu(II)Pc and its low solubility of phthalocyanines in water lead to complete adsorption on the catalyst with the molecules stacked on top of each other. On the other hand, the zeta potential (ζ) of SBA15/Fe−1 and 0.543–1.141 h−1 for the Fenton and photo-Fenton processes, respectively. In all cases, the correlation coefficients were greater than 0.99, demonstrating the good fit of the pseudo-first model. The differences between Fenton and photo-Fenton kinetic constants were 49% for photo-Fenton and 15% for Fenton, showing significantly lower OII removal rates in the latter case. Considering that the OII dye is the most recalcitrant dye, as long as this compound is removed by the nanocomposite, the rest of the dyes should be removed.Degradation due to hydrogen peroxide in an acidic medium (pH 3) occurred to a greater extent for EBT and RB, indicating that they are less recalcitrant compounds than MG and OII, whose degradation was not complete at the end of the experiment. Moreover, as observed in 3O4, Fe3O4@PAA and Fe3O4@PEI and the immobilization on mesoporous silica on Fe3O4@PAA/SBA15 and Fe3O4@PEI/SBA15 nanocomposites were evaluated on the basis of the use of different types of catalyst with equivalent magnetite loading. A concentration of 200 mg L−1 of Fe3O4 and H2O2 was used for the degradation of 10 mg L−1 of Orange II at pH 3. The degradation results are shown in Different types of magnetite-based catalysts were tested for their performance in Orange II dye removal. The influence of magnetite coatings using TMAOH-stabilized Fe3O4@PAA/SBA15 provides the best results for OII degradation, achieving complete removal of the dye for Fenton and photo-Fenton processes. However, the estimation of the kinetic constant showed that the reaction rate under irradiation was approximately 5 times higher, with a half-life of 15 min in the case of photo-Fenton, showing a R2 value greater than 0.98 in all cases. The high positive value of the zeta potential for Fe3O4@PEI nanoparticles at pH 3 causes a remarkable adsorption of the OII dye. In order to quantify the adsorption on the NPs catalyst, the pH of the medium was changed to 7 at the end of the degradation experiments to desorb the remaining dye. The difference between the initial and final concentration was less than 10%, denoting the predominant contribution of adsorption. This phenomenon could be due to the fact that the high interaction between the compound and catalysts caused surface saturation, preventing radical formation and decreasing reaction rates. On the other hand, the uncoated nanoparticles showed better results than those coated with PAA. However, their stability in aqueous media is lower, and they precipitate out of water to form agglomerates, which could hinder their industrial application. Although bare magnetite NPs showed a high zeta potential value in absolute terms compared to those coated with PAA or PEI, electrostatic repulsions were not sufficient to prevent agglomeration. The low size of the NPs causes them to move closer to each other, and magnetic interaction plays an important role in this phenomenon. The agglomeration also causes the reduction of the oxidative efficiency due to the decrease of the active surface area. In view of the results, Fe3O4@PAA/SBA15 was selected as catalysts for the next steps and used for the optimization of the operating conditions, such as the catalyst loading or the hydrogen peroxide concentration.Under these conditions, Fe−1, H2O2 concentration between 100 and 300 mg L−1 and pH in the range of 3 to 7. Considering that a pH value lower than 3 could cause the solubilization of magnetite [−1 of hydrogen peroxide concentration was selected because an excessive concentration of H2O2 can quench the process by reacting with the radicals formed [−1 was used for all experiments.The optimization of the reaction conditions took into account not only the influence of operational parameters on the removal of dye but also the selection of conditions that would ensure a balance between efficiency and reduction of operational costs, with a view on prospective application. To determine the influence of variables on OII removal, response surface methodology (RSM) was applied according to a Box-Behnken design, studying the catalyst loading between 200 and 500 mg Lagnetite , this pos formed . Considep < 0.05, indicating their influence on the kinetic constant with a probability of more than 95%. These factors were the pH (both in linear and quadratic terms), the H2O2 concentration and the interaction factor between these two variables. The system showed a similar performance compared to the work reported by other authors [Analysing the results of the effects for each variable and considering the error calculated by the replicates at the central point, four significant effects were obtained for  authors , in whic2 provided a value of 0.976, indicating that the model adequately fitted the system performance. The results obtained for the coefficients for all values are shown in 2O2 concentration was linear, with a maximum reaction rate at a load of 300 mg L−1, and the influence of the catalyst concentration was not significant according to its p value , showing minor effects due to acute toxicity (5 min)  . AccordiMoreover, the reuse tests were carried out for the Fenton mechanism (without light), in order to observe the influence of the irradiation on degradation. For these experiments, the same experimental conditions were maintained, only suppressing the light irradiation. For the experiments conducted at pH 5 and 7, there was no degradation of OII, regardless of the catalyst load and the hydrogen peroxide concentration. For this reason, the optimization was performed at pH 3. The obtained kinetic constants for these experiments are shown in −1 of OII. The kinetic constants obtained were, on average, four times lower than those obtained for the photo-Fenton experiments under the same conditions. On the other hand, their value was maintained throughout the cycles with slight variations, indicating that the reuse of the catalyst does not affect its performance  irradiated by three 11 W fluorescent lamps. Mechanical stirring was used to ensure proper mixing of the reaction volume, to avoid the interactions between magnetic fields and nanoparticles. The magnetic separation was performed by introducing a magnetic bar inside a glass tube in the volume of the reactor . The resAfter two hours of reaction, the OII dye was completely removed and the TOC concentration was partially reduced at a large extent, with removal values higher than those of laboratory scale experiments (up to 75%). Moreover, the toxicity values, related to the formation of toxic degradation intermediates, are lower than those obtained for the initial effluent .Finally, the nanocatalyst was reused to check the elimination of SMX. The kinetic constants of SMX removal are half of those achieved for OII under the same conditions. The TOC removal percentages reached values above 60% and the degradations of the target compound were, except in the first cycle, above 75% after five hours of reaction . The degOn the other hand, the main advantage of these nanocatalysts compared to the conventional ones is the easy separation of the nanoparticles from the effluent, improving their industrial application.The changes in the kinetic constant follow the same trends observed at laboratory scale. The variation of the kinetic constant values at the initial cycles could be explained by the adsorption of by-products on the catalyst surface. After the third cycle, equilibrium was reached and the differences between these values are reduced. Moreover, the differences between the kinetic constants of OII and SMX could be related to the electromagnetic interactions between the catalysts and the target compounds. In the case of OII, the group N = N has a partial positive charge mainly due to the delocalization of the charge in the carbon rings, and it has a positive charge in the hydrogen of -OH group. These positive charges increase the affinity for the negatively charged surface of the catalyst. On the other hand, the most positively charged element in SMX is sulfur, but this charge is balanced out by the negative charges of the oxygen, and the other positive charge (O of the ring) is counteracted by the N, decreasing the interaction between this compound and the catalyst.Considering the degradation pathways, advanced oxidation processes in Fenton-type processes follow non-specific oxidation pathways. In the case of sulfamethoxazole, previous studies reported that the degradation pathway in Fenton reactions could start by the oxidation of the amino group on the benzene ring, cleavage of the bond between the sulfur and the benzene ring, oxidation of the amino group or attack of the ·OH on the benzene ring and the isoxazole double bond. Thus, the degradation pathways are not unique and the formation of a wide range of intermediates takes place ,49,50. I3O4@PAA/SBA15, TEM (In order to monitor the stability of FeA15, TEM A and SEMA15, TEM B, imagesA15, TEM C,D. No cOn the other hand, XRD measurements were made initially and after the first, fifth and tenth cycles  to obser2O2. Surprisingly, for the range studied, the influence of catalyst loading was not significant. These optimum conditions were applied in the stability tests. Reusability of the catalyst was demonstrated after 10 cycles of reuse, showing low variability in the kinetics. Moreover, in all these experiments, an external magnetic field was used to separate the magnetite nanoparticles from the treated effluent, which points to this technology as a suitable process to apply in wastewater treatment.Advanced oxidation processes based on Fenton and photo-Fenton reactions are promising technologies in the field of removing emerging contaminants in wastewater. In this work, the use of coated magnetic nanoparticles or their combination in nanocomposites supported on mesoporous silica for the removal of different dyes and sulfamethoxazole was investigated. According to the results, the best performance was obtained for magnetite nanoparticles supported on SBA15 and coated with polyacrylic acid. The response surface methodology was applied to identify the influence of pH as the most influential variable on the degradation of the target compounds, followed by H


The seasonal polycyclic aromatic hydrocarbon (PAH) variability was studied in the estuaries of the Partizanskaya River and the Tumen River, the largest transboundary river of the Sea of Japan. The PAH levels were generally low over the year; however, the PAH concentrations increased according to one of two seasonal trends, which were either an increase in PAHs during the cold period, influenced by heating, or a PAH enrichment during the wet period due to higher run-off inputs. The major PAH source was the combustion of fossil fuels and biomass, but a minor input of petrogenic PAHs in some seasons was observed. Higher PAH concentrations were observed in fresh and brackish water compared to the saline waters in the Tumen River estuary, while the PAH concentrations in both types of water were similar in the Partizanskaya River estuary, suggesting different pathways of PAH input into the estuaries. The annual riverine PAH mass flux amounted to 0.028 t/year and 2.5 t/year for the Partizanskaya River and the Tumen River, respectively. The riverine PAH contribution to the coastal water of the Sea of Japan depends on the river discharge rather than the PAH level in the river water. Polycyclic aromatic hydrocarbons (PAHs) are a class of hydrophobic organic compounds composed of several fused aromatic rings. They are widespread environmental pollutants due to the stability imparted by their lack of functional groups. Furthermore, some PAHs are carcinogenic and toxic as well as bioaccumulative in food chains ,2,3. ThuSignificant amounts of PAHs are released into the environment, including the water compartment, since they occur with the burning of fossil fuels, and, moreover, are part of them, and the consumption of fossil fuels globally is high today . The estEstuaries of the Sea of Japan, in particular of its Russian northwestern region, are important to the fisheries industry of countries around the sea . They serve as nursery, feeding and refuge areas for commercially important species of fish such as salmonids and various shellfishes , providiThe objective of this study was to assess the estuarine PAH pollution of the two rivers of the Sea of Japan, namely the Tumen river and the Partizanskaya river, taking into account seasonal PAH variability, and to estimate potential environmental risks. Furthermore, since the estuary is formed by sea and river waters, the relationship between PAH and salinity was examined to understand the PAH pathway to the estuary (from the sea or with river runoff) and its influence on PAH dispersion in the estuary system. Additionally, annual and seasonal PAH riverine mass fluxes to the coastal environment were calculated to design the future PAH budget for the Sea of Japan.2. China owns 70% of the river’s catchment; almost 30% is owned by North Korea, and Russia’s share in the downstream catchment is less than 1%. According to data from the early 2000s, the population of the river basin area was 2.2 million people. The Tumen River supplies water for human consumption, agricultural irrigation and industrial development in China and North Korea. Its source is located on the Changbai Mountain Plateau in the DPRK, and a significant part of the river’s length is in the middle between the North Korean and the East Manchurian Mountains, forming the border between the DPRK and China. In the lower reaches, the river forms part of the border between the DPRK and Russia. The Tumen River eventually flows into Peter the Great Bay (the northwestern Sea of Japan) as two water streams. One is a main water stream 600 m wide and another is much smaller, periodically overlapping a sand drift. In the main water stream, the sea-water intrusion occurs from the river bar into the upstream river over 3 km. The discharge volume rate of the Tumen River is about 200 m3/s (in May and October) pyrene-d12 was added to the SPE cartridges and the filters. PAHs were eluted from the filters and SPE cartridges by different methods. The DPAHs were desorbed from the SPE cartridges using 15 mL of dichloromethane. The solution was concentrated by rotary evaporation and the DPAHs that remained were dissolved in 1 mL of hexane for cleaning up on silica gel cartridges . First, the silica cartridges were preconditioned by 5 mL of hexane, then the extracts were applied to the cartridges. The DPAHs were eluted from the cartridges by 15 mL of hexane in acetone , and 200 μL of dimethylsulfoxide (DMSO) was added to the solution. The solvent was removed by rotary evaporation until only DMSO and the residue was dissolved in 800 μL of acetonitrile for the HPLC analysis.Prior to HPLC analysis, 20 μL of an internal standard containing naphthalene-v/v). The combined solution was extracted by liquid–liquid extraction with 80 mL of sodium hydroxide solution (5%), 80 mL of sulfuric acid solution (20%) and 80 mL of Milli-Q water (performed twice). The DMSO (200 μL) was added to the solution, and the solvent was removed by rotary evaporation. The remaining DMSO was reconstituted to 1 mL in acetonitrile for HPLC analysis.The filters containing PPAHs were ultrasonicated twice by 40 mL of benzene in ethanol . An Inertsil ODS-P analytical column  and an injection volume of 20 µL were employed. The temperature of the column was kept constant at 20 °C. The mobile phase was a mixture of acetonitrile–water delivered in gradient mode with acetonitrile increasing from 55 to 100% over 60 min. The flow rate of the mobile phase was maintained at 1 mL/min. Both the excitation and emission wavelengths of the fluorescence detector were set at optimum wavelengths for each PAH with a time program.A total of 13 PAHs from the USEPA’s 16 priority PAHs list were quantified: the 3-ring PAHs were acenaphthene (Ace), fluorene (Fle) and anthracene (Ant); the 4-ring PAHs were fluoranthene (Flu), pyrene (Pyr), benz[a]anthracene (BaA) and chrysene (Chr); the 5-ring PAHs were benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), benzo[a]pyrene (BaP) and dibenzanthracene (DBA); the 6-ring PAHs were benzoperylene (BPe) and indeno pyrene (IDP). The analytical data of Nap and Phe were not reported due to the low recovery of Nap in the particulate phase and the imperfect resolution of Phe with interfering peaks for the dissolved phase. In addition, acenaphthylene does not fluoresce and was thus also excluded from analysis. Three-ring compounds are low molecular weight (LMW) PAHs and five- to six-ring compounds are high molecular weight (HMW) PAHs.The limit of detection (LOD) and limit of quantification (LOQ) were evaluated based on signal to noise ratio cut-offs of 3 and 10, respectively. The LOD ranged between 0.04 pg/injection (Ant) and 2.86 pg/injection (IDP). The LOQ varied between 6 ng/L (Ant) and 477 ng/L (IDP).To detect the contamination due to sampling and pre-treatment procedures, two field blanks were performed for every seasonal sampling; in addition, two laboratory blanks for each set of estuarine samples were prepared and treated. Average field blank data ranged from below LOD to 0.2 ng/L (Ace), and the PAHs with concentrations higher than the LOQs were subtracted from the related PAH concentrations in the samples; laboratory blank data were below the LOD and LOQ data and were not taken into account.d10, 68.9 ± 9.18 and 84.2 ± 7.17 for Phe-d10, 80.6 ± 10.24 and 83.8 ± 9.83 for Pyr-d10, 104.6 ± 12.35 and 101.6 ± 8.40 for BaP-d12 for dissolved and particulate samples, respectively (n = 100 for each phase).The internal standard procedure was used for quantitation. Recoveries of PAH internal standards were 64.9 ± 7.43 and 85.4 ± 7.41 for Ace-PAHs is the concentration of an individual PAH, CQV is the quality values for each PAH. Based on QV such as the negligible concentrations (NCs) and the maximum permissible concentrations (MPCs) of PAHs taken from [QV(NCs) was the quality values of the NCs of PAHs and CQV(MPCs) was the quality values of the MPCs of PAHs  calculated using the following formula [3/s; Ci—daily concentration of TPAH (a sum of DPAHs and PPAHs). The daily TPAH concentration in the estuaries, based on the average values of surface and bottom TPAHs, was calculated using the equation of a linear relationship between PAH concentrations and river discharge on sampling days .Principal component analysis (PCA) is a multivariate statistical method for examining factors to reveal relationships and patterns within datasets, and it has been used to identify PAH origins ,22. PCA The average annual concentration of TPAHs was 33.3 ± 35.1 ng/L in the Tumen River estuary and 20.3 ± 10.6 ng/L in the Partizanskaya River estuary . Table 1The average annual concentrations of DPAHs and PPAHs were 17.6 × 13.8 and 15.7 × 21.7 ng/L in the Tumen river estuary and 15.4 × 9.5 and 5.3 × 2.6 ng/L in the Partizanskaya river estuary . No statIn the Tumen River, the PAH concentrations in the estuarine samples were below those in the middle river reach samples, with mean annual PAH concentrations of 68 and 104 ng/L re-estimated for the 13 researched DPAHs and PPAHs, respectively . ApparenThe mean seasonal TPAHs concentration of the Tumen River varied from 15.6 to 83.2 ng/L over the year, with the highest concentrations occurring in the summer a. The meIn the Partizanskaya river estuary, the trend in seasonal PAH variation is typical for regions under climatic conditions with a cold season and is described in a number of works, including for coastal water of the northwestern Sea of Japan ,27,31. TIn the Tumen River, the seasonal PAH variability is similar to the trend found for some water bodies located at latitudes similar to the areas under study. An increase in TPAHs was found in the warm, wet period, explained by a higher run-off PAH input due to heavy precipitation, as well as greater solubility of PAHs at elevated temperatures ,33. AccoFurthermore, it has been shown that PAHs in river systems can be derived from soil pollution . TherefoThe relative TPAH concentrations in the estuaries of the Tumen and Partizanskaya rivers are shown in For both estuaries, the relative PAH contents in the dissolved and particulate phases were similar . PAHs wiThere was a decrease in the share of PAHs with three rings in the summer, which was less pronounced in the Tumen River and stronger in the Partizanskaya River. This can be attributed to changes in hydrological and biogeochemical conditions due to summer river flood. With increasing river discharge, an increased concentration of trace metals in many rivers, including rivers of the Northwestern Sea of Japan, was observed ,38. SomeSeasonal variability in the proportion of HMW PAHs demonstrated that in the Partizanskaya river estuary, the highest relative contribution of 5–6-ring PAHs was in the autumn. This suggests PAH input from pyrogenic sources. As for the Tumen river estuary, higher 5–6-ring PAHs were observed in summer. In this period, PAH pollution of the Tumen river estuary is heavily influenced by the input of surface run-off with PAHs stored for a time in the soil. Probably, HMW PAHs were degraded more slowly than others, and, therefore, as run-off was magnified in the summer, the fraction of 5–6-ring PAHs may become prominent in other seasons.To identify the origin of PAHs in the estuaries, we used Flu/(Flu + Pyr) and IDP/(IDP + BPe) ratios since these ratios are sufficiently conservative, according to . NeverthIn the Partizanskaya River estuary, most of the Flu/(Flu + Pyr) ratio values indicated that PAH originated from the burning of fossil fuels and biomass for the seasons from winter to summer. However, in the autumn, the Flu/(Flu + Pyr) ratio values were relatively separated from the others and shifted towards the range of petrogenic values (0.38 ± 0.08) a. For thAdditionally, PCA was used to provide further details on the PAH sources that drive seasonal PAH variation during the year. PC1 represented 44% of the variance for the Partizanskaya River estuary. The score plot shows that samples of this river were isolated into three groups a. The grPC2, representing 19% and 28% of the variance for the Partizanskaya River and the Tumen River, respectively, did not reveal any seasonal differences between samples and is probably related to the influence of hydrological and meteorological events.In the Partizanskaya River, enrichment of 3-ring PAHs in the winter samples indicates a petrogenic PAH input, and this contradicts the Flu/(Flu + Pyr) ratio results. This can be attributed to the fact that the diagnostic ratio determines the main PAH source, while minor ones remain hidden . ClusterAn estuary is a river–ocean transitional zone where freshwater and sea water mixtures occur . In ordeFurthermore, depending on the estuary morphology and whether PAHs enter into the estuary with saline or fresh water, the fate of PAH in the estuary ecosystem will vary. Since both estuaries studied are highly stratified ,18, theyMPCs was <1 for each PAH, while the RQNCs values varied over the year. As shown in NCs > 1, were found for the Tumen River estuary in summer. The eco-toxicological risks of these compounds had reached moderate levels during this period according to the risk classification of individual PAHs  [NCs >1 increased slightly in autumn and winter in both estuaries.The results showed that, in both estuaries, RQNCs > 1) . It shouNCs > 1) . FurtherIn conclusion, in general the ecotoxicological risk levels were moderate for LMW PAHs and low for HMW PAHs over the year in the estuaries except in the summer in the Tumen river estuary when the RQ values were increased for the majority of PAHs. Nevertheless, it should be taken into account that the mixed effects of multiple contaminants can have a more significant hazard impact on the ecosystem than single-compound exposure. Therefore, the management of PAH pollution in the Tumen Estuary should be considered, especially in summer.The seasonal and annual river TPAH mass flux was estimated based on the daily PAH flux calculated using the Formula (4).The results presented in Regarding seasonal variability in PAH riverine input, the maximum TPAH contribution of both rivers, Partizanskaya and Tumen, occurred in summer, which is consistent with the highest TPAH concentrations found for this season in the Tumen River and contrasts with the results for the Partizanskaya River, where the highest concentrations were found in the winter. The summer PAH contribution of the Partizanskaya river amounted to 55% or more of the annual input, and that of the Tumen was 86%. The highest discharge from rivers was observed in summer; consequently, the mass PAH flux into the coastal area of the northwestern Sea of Japan depended on the discharge of rivers rather than the level of PAH pollution. The effect of flood events on PAH mass flux to the marine environment was observed for the Rhone River when 77% of the annual PAH mass flux was discharged to the Mediterranean Sea during the major flood event . The resThis study examined the seasonal PAH pattern in the estuaries of the Tumen River and Partizanskaya River, which flow into the Northwestern Sea of Japan. On a global scale, the PAH levels were still low in comparison with other water bodies. However, there was PAH enrichment and, consequently, heightened environmental risks for estuarine ecosystems due to seasonal factors, leading to moderate levels of PAHs. A survey of the estuaries showed different trends in the seasonal PAHs variations influenced by humans or natural impacts. Furthermore, the main PAH pathway in the estuaries was also different; for the Tumen River it was polluted riverine water, while PAH pollution of the Partizanskaya River was caused by atmospheric PAH input from nonpoint sources. In addition to assessing the PAH level and environmental risks, we calculated annual and seasonal riverine PAH mass fluxes. The largest PAH contribution of both rivers into the Sea of Japan was in the summer and primarily resulted from the high river discharge.


These changes were compared with those provoked in the lipids of corn oil and of virgin flaxseed oil submitted to the same digestive conditions. Lipolysis and oxidation were the two reactions under consideration. The bioaccessibility of main and minor components of olive oil, of phenolic compounds added, and of compounds formed as consequence of the oxidation, if any, were matters of attention. Enrichment of olive oil with antioxidant phenolic compounds does not affect the extent of lipolysis, but reduces the oxidation degree to minimum values or avoids it almost entirely. The in vitro bioaccessibility of nutritional and bioactive compounds was greater in the olive oil digestate than in those of other oils, whereas that of compounds formed in oxidation was minimal, if any. Very close quantitative relationships were found between the composition of the oils in main components and their in vitro bioaccessibility. These relationships, some of which have predictive value, can help to design lipid diets for different nutritional purposes.The changes provoked by in vitro digestion in the lipids of olive oil enriched or not with different phenolic compounds were studied by proton nuclear magnetic resonance ( Digestion is a very complex process in which the main reactions provoke hydrolysis of proteins, carbohydrates and lipids to yield smaller building blocks, which may be absorbed through the intestinal wall. Furthermore, other secondary reactions, such as oxidation, Maillard reaction, and even esterification among others, can also be produced during digestion ,2,3. AllLipids are an important group of macronutrients which include many different compounds. Triglycerides are their main components, and edible oils are the principal food lipid. During oil digestion triglycerides are hydrolyzed to give smaller molecules, of which only fatty acids and monoglycerides can be absorbed. Lipolysis extent determines the yield of molecules derived from oil main components that are able to be absorbed. Knowledge of the factors that influence the lipolytic process is a subject of great importance in monitoring the digestive process and designing lipids and mixtures of lipids with other components to cover different nutritional needs . In thisIn addition to lipolysis, lipid oxidation can also take place during digestion ,12,13,14When edible oils are submitted to digestion, the above-mentioned reactions can also affect minor oil components, and the nature and properties of these can also, in turn, influence the digestive process . As is kIn summary, in order to advance in the understanding of the in vitro digestion of edible oils and to achieve a broad view, both of the evolution of the process and of the bioaccessibility of the compounds involved, as many influential factors as possible should be taken into account.1H NMR spectroscopic data of the lipid extracts of the digestates. In order to have a complete view of this lipolytic process the results will be analyzed jointly with those of other oils such as corn oil and virgin flaxseed oil, these latter from previous studies O) and O1DG2 (with an enrichment of 1.36 mmol DG/mol [FA+AG]O). The samples enriched with hydroxytyrosol acetate, were named O1HTA1 (with an enrichment of 0.28 mmol HTA/mol [FA+AG]O) and O1HTA2 (with an enrichment of 2.53 mmol HTA/mol [FA+AG]O). Finally, the oil O2 samples enriched with different concentrations of gamma-tocopherol were named O2γT1 (with an enrichment of 0.11 mmol γT/mol [FA+AG]O), O2γT2 (with an enrichment of 1.17 mmol γT/mol [FA+AG]O) and O2γT3 (with an enrichment of 12.58 mmol γT/mol [FA+AG]O). These enrichment levels were set in function of the solubility of these compounds in the oil. Thus, the above concentrations were obtained in order to reach enrichment degrees near to 0.02% and 0.2% in weight for the three phenolic compounds and, in addition, near 2% in weight in the case of gamma-tocopherol due to its high solubility in oils. However, this latter level of enrichment was not possible for dodecyl gallate and hydroxytyrosol acetate because of their limited solubility in oils. All these samples were submitted to in vitro digestion.Aliquots of olive oil OAspergillus oryzae ; pepsin from porcine gastric mucosa ; amano lipase A from Aspergillus niger ; pancreatin from porcine pancreas (P1750); lipase type II crude from porcine pancreas ; and bovine bile extract (B3883). The digested samples were named like the original samples preceded by D . Two digestion experiments, each including duplicate samples, were performed. Blank samples corresponding to the mixture of juices submitted to digestive conditions were also taken for further analysis.Aliquots (0.5 g) of the above-mentioned samples were digested by using a semi-static in vitro gastrointestinal digestion model developed by Versantvoort et al. 2005) [05 [20]. 2Cl2, HPLC grade, Sigma-Aldrich) following a methodology that also allows fatty acid extraction as in previous studies +[MG])D/([FA]+[AG])D, because the only absorbable compounds coming from oil main components are fatty acids, FA, and monoglycerides, MG. For any other compound X present in the oil sample before digestion or not, the equation to be used to determine the bioaccessibility in this approach is Bx = [X]D/([FA]+[AG])D, where [X]D is the concentration of the compound X in the lipid extract of the digestate.The in vitro bioaccessibility of a compound can be defined as the concentration of the compound that remains absorbable after in vitro digestion. This concentration may refer either to an internal reference or to the initial concentration of the compound in the sample before digestion. The first approach is much more general because it can be used for compounds formed during digestion and absent in the sample before digestion. In this study the internal reference can be the concentration of oil main components expressed by the sum of the concentration of fatty acids plus acyl groups in the digestate ([FA]+[AG])D and the concentration in the oil before digestion, [X]O, as indicated in the equation B′x = [X]D/[X]O. This definition gives information about the loss of the compounds during in vitro digestion, or about the fraction of the compounds released during digestion that are really absorbable as in the case of oil main components. For oil main components, BOMC and B′OMC are very similar because the reference is barely modified during digestion. In the second approach, bioaccessibility B′ can be estimated by the ratio between the concentration of the compound in the lipid extract of the digestate [X]1, DO1DG1, DO1DG2, DO1HTA1, DO1HTA2, DO2, DO2γT1, DO2γT2, and DO2γT3) and the mixtures O1DJ and O2DJ of digestive juices DJ, after undergoing digestion conditions, and olive oils O1 and O2. The comparison of the headspaces of the several samples enables one to deduce differences provoked by in vitro digestion. The operating conditions were the same as those used in previous studies D, given in moles, by the equation BPC = [PC]D/[FA+AG]D. This definition gives direct information about the concentration of these bioactive compounds in the digestate, and so is comparable with that of the minor and main oil components. PC thus defined for hydroxytyrosol acetate in DO1HTA2 and for gamma-tocopherol in DO2γT1, DO2γT2 and DO2γT3. As expected, these values are higher the higher the enrichment degree in the oils before digestion. Likewise, in vitro bioaccessibility can also be defined by the ratio between the concentration of the compound in the lipid extract of the digestate [PC]D and the concentration in the oil before digestion, [PC]O, both in the same units, as indicated in the equation B′PC = [PC]D/[PC]O. This definition gives information about the loss of the compound during in vitro digestion, or about the fraction of the phenolic compound added to the oil that remain in the digestate. B′PC data of the same compounds above mentioned are given in gamma-tocopherol in olive oil than in the other oils that have higher unsaturation degree is an important fact. It must be remembered that hydroxytyrosol acetate has been attributed beneficial health effects, such as, anti-inflammatory, antioxidant and ability to inhibit of platelet aggregation [gamma-tocopherol [However, as mentioned before, hydroxytyrosol acetate was detected in the lipid extract of the digestate of the most enriched olive oil sample, DOregation ,61. Likecopherol ,51,52. F1 or they have been detected in DO2 digestate, in a much smaller concentration than in the digestates of the other oils such as DC and DF. This concentration represents the bioaccessibility B of hydroperoxydes in each digestate. Furthermore, as already mentioned, these hydroperoxydes could be expected to be absorbable, with the consequent negative effects on human health, because presumably oxidation during digestion will be produced in fatty acids rather than in acyl groups, due to the lower oxidative stability of the former.In this study, and in other previous studies ,12,13,14In addition, as gamma-tocopherol, does not modify either the lipolysis extent reached during in vitro digestion or the in vitro bioaccessibility of oil main components. It has been demonstrated that, unlike other polyphenolic compounds, these phenolic compounds do not inhibit lipase activity.The lipolysis extent produced during the in vitro digestion of olive oil is high, yielding an important release of monoglycerides and fatty acids, and as consequence, the in vitro bioaccessibility of the olive oil main components is also high, and both are greater than of those edible oils having higher unsaturation degrees, such as corn oil and virgin flaxseed oil. For the first time very, close quantitative relationships have been found between the composition of the oil, expressed in molar percentages of the different kinds of acyl groups, and its vitro bioaccessibility. It has been proved that the in vitro bioaccessibility of the oil main components is directly related with the concentration in the oil of saturated and of oleic acyl groups, the weight of the first being almost ten times higher than that of the second. Likewise, it has been proved that in vitro bioaccessibility of the oil main components is inversely related with the concentration of the linolenic and of linoleic acyl groups in the oil, the weight of the former being double than that of the latter. Some of the obtained equations have predictive ability and are able to predict with a high level of approximation the in vitro bioaccessibility of the main components of oils not involved in the development of these equations. It has also been demonstrated that the intake of a similar amount of edible oils of different composition in acyl groups, can have very different nutritional effects, caused by, among other reasons, the different lipolysis extent reached during digestion. These differences in lipolysis extent have as their consequence differences in the bioaccessibility of the oil main components that could be absorbed through the intestinal wall. The models developed that relate in vitro bioaccessibility of oil main components and oil composition provide a very valuable tool for designing diets for very different purposes and for special needs in which high or low lipid bioaccessibility may be required. Enrichment of olive oil with different concentrations of phenolic bioactive compounds, such as dodecyl gallate, hydroxytyrosol acetate or 1H NMR spectroscopy but only by the abundance of volatile oxidation markers analyzed by the very sensitive SPME-GC/MS technique. In all cases, the oxidation extent reached during in vitro digestion of olive oils is much smaller than that reached during the digestion of other edible oils such as corn and virgin flaxseed oil, with the consequent repercussions on health due to the toxicity of oxidation compounds. Enrichment of olive oils with phenolic compounds either reduces the oxidation extent produced during in vitro digestion to minimum values or prevents it almost totally. It has been demonstrated again that the antioxidant efficiency of these compounds is in line with the number of phenolic groups in its molecule, which means that dodecyl gallate has higher antioxidant efficiency than hydroxytyrosol acetate, and the lowest antioxidant efficiency, under these in vitro digestion conditions, is that of gamma-tocopherol.Furthermore, the oxidation extent reached during the in vitro digestion of olive oil is very small, and in some cases is undetectable by It has been shown that the concentration of minor olive oil components such as squalene, some sterols, as well as terpenes and sesquiterpenes is not modified during the in vitro digestion, these being totally bioaccessible after digestion. This is of great importance due to the different beneficial bioactive capabilities attributed to most of them. The in vitro bioaccessibility of the added phenolic compounds, which are very interesting bioactive compounds, is higher in the digestate of olive oil than in those of corn and virgin flaxseed oil. This could be related to the lower oxidation extent produced during digestion of olive oil than during digestion of corn or virgin flaxseed oil. Nevertheless, estimation of the in vitro bioaccessibility of dodecyl gallate and of hydroxytyrosol acetate—the latter at the lower concentration essayed—was not possible, probably due to their hydrolysis during digestion which yields very bioactive polar compounds that remain in the aqueous fraction of the digestate. Finally, due to the very low oxidation level reached during in vitro digestion of olive oil, the bioaccessibility of the oxidation compounds formed, if any, is much smaller in the digestate of olive oil than in those of corn and virgin flaxseed oil with the consequent repercussions on health.Among these oxidation compounds, there are aldehydes that are generated in much greater abundance in the oils having higher unsaturation degree. The great ability of aldehydes to react with nitrogenated compounds such as proteins by reactions of a Maillard type, and for this reason with enzymes including lipases, could be underlined as a potential cause of the smaller lipolysis extent produced during the in vitro digestion of the most unsaturated oils.


This study aimed to investigate the effectiveness of 2,4,4′-trihydroxychalcone as a natural antioxidant on the oxidation of sunflower oil during an 88-day storage period and to compare its strength with the synthetic antioxidant butylated hydroxytoluene (BHT). Seven groups of the sunflower oil samples were prepared: pure oil (control), oil treated with different concentrations  of 2,4,4′-trihydroxychalcone, and oil treated with different concentrations  of BHT. Specific parameters, namely, the peroxide value (PV), acid value (AV), p-anisidine value (p-AnV), thiobarbituric acid reactive substance (TBARS) value and total oxidation (TOTOX) value were used to assess the extent of the deterioration of the oil by estimating the primary and secondary oxidation products. The results showed that 2,4,4′-trihydroxychalcone effectively decreased the production of the primary and secondary oxidation products of sunflower oil during storage, as indicated by reductions in the PVs, AVs, p-AnVs, TBARS values and TOTOX values of the sunflower oil. When compared to BHT, 2,4,4′-trihydroxychalcone showed either a similar or stronger effect in inhibiting the primary and secondary oxidation products. These findings suggest that, 2,4,4′-trihydroxychalcone is a suitable natural alternative to synthetic antioxidants to improve the oxidative stability of sunflower oil. Lipid oxidation, which affects the color, taste, and texture of food, is the leading cause of food quality deterioration, resulting in the decreased shelf life of food . FurtherOver the last century, the consumption of vegetable oils has increased dramatically. One of the best of these products is sunflower oil, which includes 59% of polyunsaturated fatty acids in the form of linoleic acid and 30% of monounsaturated fatty acids in the form of oleic acid . SunflowGlycyrrhiza uralensis), which is an important Chinese materia medica frequently used in clinical practice [Natural antioxidants have gained considerable attention as a source of biologically active compounds due to their multiple health effects ,18, and practice . Licoricpractice ,22. The practice ,23. HoweThe peroxide value (PV) method was used to measure the degree of primary oxidation of the sunflower oil for five different storage periods  in the presence and absence of natural and synthetic antioxidants. As the storage period increased, the PV of the pure sunflower oil increased significantly from nearly 3 meq/kg to around 80 meq/kg on day 88 . There wThe free fatty acids (FFAs) in the sunflower oil were determined by measuring the oil’s acid value (AV). Generally, as the storage period increased, the AV of the control oil sample increased; however, only the AVs at the last three storage periods  were significant with zero time. Similarly, the AVs of all the treated samples increased over time. As shown in The secondary oxidation of the sunflower oil was determined by measuring the p-anisidine values (p-AnVs). While there was a remarkably significant increase in the p-AnVs of the control samples during the storage periods, the samples with antioxidants showed a nonsignificant increase. Thiobarbituric acid reactive substance (TBARS) values were also used to determine the secondary oxidation of the sunflower oil. As the storage time increased, the TBARS values for the pure sunflower oil and the oils containing the antioxidants increased. At the end of the storage period, the highest dose of the natural antioxidant (1000 ppm) significantly decreased the formation of malondialdehyde (MDA) in the sunflower oil compared to the other two doses . On the other hand, the TBARS value of the oil with the highest concentration of synthetic antioxidant (1000 ppm) was significantly lower than that of the oil with the lowest concentration (100 ppm). As shown in (TOTOX) values represent the oxidative degradation index because they account for both primary and secondary products  . In thisThe present study evaluated the effects of 2,4,4′-trihydroxychalcone as a natural antioxidant at different concentrations  on the oxidative stability of sunflower oil during storage for 88 days. These effects were compared to those of pure sunflower oil and sunflower oil with BHT. The primary and secondary oxidative compounds produced during the storage periods were determined using various assays, including PV, AV, p-AnV, TBARS, and TOTOX.PVs are used to detect peroxide formation in the early oxidation stages of lipids . In thisThe AV is a standard parameter used to measure the rancidity of oils and is an indicator of fat hydrolysis. In this study, an increment in the amount of FFAs as a function of storage was observed for all the sunflower oil samples at all the time intervals, which indicated the hydrolysis of triglycerides. The structure of these FFAs comprises a hydrophobic and a hydrophilic group. The hydrocarbon chain is the hydrophobe, and the carbonyl group is the hydrophilic part. The carbonyl group of these components is ideally concentrated on the surface of edible oils where it reduces the surface tension, increases the rate of oxygen diffusion from the headspace into the oil, and thus accelerates the oxidation of the oil . In thisThe p-AnV is used to measure the products of secondary lipid oxidation produced when hydroperoxide decomposes into aldehydes, carbonyl, ketones, and carboxylic acids. This decomposition creates the rancidity flavor of oil . The priGarcinia mangostana Linn. peel extracts) at the same concentrations. By day 24, the sunflower oil with the mangostana peel extracts at 200 ppm and the sunflower oil with BHA exhibited comparable inhibitory effects against the secondary oxidation. They therefore suggested that mangosteen peel extracts at higher concentrations are able to prolong the shelf life of sunflower oil for a longer time.TBARS is the most common method used to measure secondary oxidation products such as MDA, which is the standard biomarker generated from the decomposition of lipid hydroperoxide . The MDAThe TOTOX values were calculated to obtain overall the oxidative stability of the sunflower oil and to measure the primary and secondary oxidation products . At the Fresh sunflower oil was obtained from a local oil press shop in Jeddah, Saudi Arabia. The oil sample was divided into seven groups: pure oil (control), oil treated with different concentrations  of 2,4,4′-trihydroxychalcone  and oil treated with different concentrations  of BHT (synthetic antioxidant). The sunflower oil samples were prepared according to the method described by Rashidch et al.  albeit wv/v) solution was added until the oil dissolved. A saturated potassium iodide solution (0.5 mL) was added, and the mixture was shaken by hand for 1 min. It was kept in the dark for 5 min followed by the immediate addition of deionized water (30 mL). The oil sample was then titrated against 0.1 N sodium thiosulfate (Na2S2O3) with constant and vigorous agitation until the yellow color disappeared. Subsequently, 1 mL of starch indicator (1%) was added, and the titration was continued until the blue color disappeared. The blank sample was analyzed under similar conditions. The volume of titrant was used to calculate the PV according to the following equation:The PV is one of the most widely used measurements for assessing oxidative deterioration in oils and fats. It specifically measures the concentration of the peroxides and hydro peroxides formed in the early stages of lipid oxidation . The PV Peroxide value = meq peroxide per kg of sampleS = volume of titrant (mL) for sampleB = volume of titrant (mL) for blank2S2O3 solution (meq/mL)N = normality of NaThe AV provides the measure of the proportion of FFAs in a substance and is used as an indicator of fat (triglycerides) hydrolysis. The AV can be defined as the milligrams of potassium hydroxide (KOH) required to neutralize the FFAs present in a 1 g sample. In this study, the AV of sunflower oil was determined using an alkali titration method according to the AOAC official method 969.17  with somA = volume of titrant (mL) for the sampleB = volume of titrant (mL) for the blankM = molarity of KOHW = weight of oil (g)w/v) (solution B). The mixture (solution B) was shaken vigorously and kept in the dark. After standing for 10 min, the absorbance was measured at 350 nm. The blank of solution B was prepared by adding 5 mL of isooctane to 1 mL of the p-anisidine solution. The p-AnV was then calculated according to the following equation:P-AnV analysis is a method used to measure the secondary lipid oxidation product when hydro peroxide decomposes into carbonyl, ketones, and aldehydes, a stage that leads to the rancid flavor of oil . This meAs = absorbance of test solution B at 350 nmAb = absorbance of test solution A at 350 nmm = mass of the substance to be examined in test solution A (in grams)w/v), 1.5 mL 20% acetic acid , and 1.5 mL of 0.8% 2-thiobarbituric acid solution in water (w/v), then the mixture was homogenized. The sample was heated in a water bath (100 °C) for 60 min until a pink color developed. The tube was cooled, and the sample was then centrifuged at 4300 g for 10 min. The supernatant was finally absorbed using a spectrophotometer at 532 nm. The concentration of MDA in the sample was determined by comparing the average optical density (absorbance) of the sample to a standard curve. A five-point standard curve was used to determine the unknown. First, a stock of a tetramethoxypropane (TMP) solution at a concentration of 200 μg/mL was prepared by adding 10 μL TMP (0.997 g/mL) to 50 mL distilled water. Next, from this stock solution, five aliquots of 0.5, 2.5, 5, 7.5, and 10 mL were taken and added to each volumetric flask, and the volume was completed to 10 mL by adding distilled water to prepare the five standard solutions with 10, 50, 100, 150, and 200 μg/mL concentrations, respectively. At each storage time, fresh TMP stock and standard solutions were prepared.The TBARS value is defined as the quantity of MDA (in mg) present in a 1 kg of sample. The TBA value is an index of lipid oxidation and measure MDA content. This method is based on the spectrophotometric quantification of the pink complex formed from the reaction of TBA with MDA . In thisThe TOTOX value is obtained by measuring the primary and secondary oxidation products of a sample, which reflect the initial and later stages of oil oxidation. Based on the calculated PVs and p-AnVs, the TOTOX values of the oil samples in this study were determined using the following equation :TOTOX=2PPV = peroxide Valuep-AnV = P-anisidine Valuep < 0.05.The collected data were analyzed using a two-way ANOVA with the different samples  at the different storage periods, followed by a comparison of the different doses  of the natural and synthetic antioxidants individually at the different storage periods. All the statistical analyses were performed using the statistical software Prism 7 . All the independent analyses were replicated in quadruplicate, and the results were expressed as mean ± SEM. The statistical significance levels were based on a confidence level of 95% as In the present study, different assays were used to evaluate the efficacy of the antioxidant 2,4,4′-trihydroxychalcone at 100, 500, and 1000 ppm concentrations in sunflower oil. It worked effectively to inhibit the formation of the primary and secondary oxidation products of sunflower oil during the 88 days of storage. It also showed either comparable or better effects than the synthetic antioxidant. The findings indicated that 2,4,4′-trihydroxychalcone can be used as a potent source of natural antioxidant to stabilize of sunflower oil. Future studies should focus on investigating the effects of this natural antioxidant on the oxidation of other types of edible oils.


Percutaneous endoscopic lumbar disectomy (PELD) is one of the most popular minimally invasive techniques of spinal surgery in recent years. At present, there are 2 main surgical approaches in PELD: foraminal approach and interlaminar approach. What's more, foraminoplasty is a necessary step for both approaches. However, there are few biomechanical studies on the formation of different parts of the intervertebral foramen. The aim of this study is to explore the effects of different foraminoplasty methods on the biomechanics of the corresponding and adjacent segments of the lumbar through a 3-dimensional finite element model analysis.We established a normal 3-dimensional finite element mode of L3 to L5, simulated lumbar percutaneous endoscopy by doing cylindrical excision of bone whose diameter was 7.5 mm on the L5 superior articular process and the L4 inferior articular process, respectively, so that we obtained 3 models: the first one was normal lumbar model, the second one was the L4 inferior articular process shaped model, and the third one was the L5 superior articular process shaped model. We compared the biomechanics of the intervertebral disc of L3/4 and L4/5 when they were in the states of forward flexion, backward extension, left and right flexion, and left and right rotation on specific loading condition.If the outcomes indicate the trial is feasible and there is evidence that one of the foraminoplasty technique may make few differences in biomechanics of corresponding lumbar intervertebral disc, we will proceed to a definitive trial to test the best way to foraminplasty, which could make biomechanical influence as little as possible.Trial Registration: Chinese Clinical Trial Registry, ChiCTR1900026973. Registered on September 27, 2019. The results of calculation have strong repeatability and avoid the difficulty of corpse specimen sampling. It has unique advantages in simulating human body structure and analyzing biomechanical characteristics.Throughout the research on foraminoplasty of PELD worldwide, most of them are limited to the analysis on the clinical efficacy of different types of foraminoplasty, but few researches have been reported on the biomechanical research which has far-reaching impact on the mid-and long-term spinal degeneration after surgery. In order to simulate the different forming on intervertebral foramen, the 3-dimensional finite element method was used to simulate the osteotomy of different parts  and sizes  on the L5 superior articular process in L4/5 segment of PELD, so as to study the influence of stress and strain for corresponding segment (L4/5) and adjacent segments  through different methods of foraminoplasty.2A reasonable and effective 3-dimensional finite element model of L3 to S1 of the lower lumbar spine was constructed by 3-dimensional finite element method, and on the basis of the model, 3-dimensional finite element models of L4/5 with different foramen forming modes were constructed. By analyzing the stress and strain of the above models under different motion states, we could know:which region of foramina formation has less influence on the mechanics of the intervertebral disc or facet joint of corresponding segment or adjacent segment and on the stability of the spinal segment?what diameter of foramina formation has less influence on the mechanical properties and stability of the spinal segment?It is small and convenient for clinical operation.33.1The CT images of the L3 to L5 of 40 male and 40 female normal adults in China were collected. The trial was examined and approved by the Ethics Committee of the Hospital of Chengdu University of traditional Chinese medicine (No. NS-5279).3.2The age of applicants is between 20 and 60 years old in good health and they are good at spirit and intelligence. They obey the arrangement of the research group, accept the treatment plan designed by the research group and sign the informed consent.3.3Participants suffered from severe spinal degeneration or severe irreversible damage of multiple spinal columns such as spinal tuberculosis and tumor.3.4Siemens Somatom Sensation 64-slice spiral CT is used for CT scanning; surface design software Creo 3.0, medical image processing software Mimics 16.0, and reverse engineering software Geomagic Studio 12.0 are used for 3-dimensional model building; finite element analysis software ANSYS 15.0 is used for 3-dimensional model processing and biomechanical finite element analysis.3.5We used spiral CT to scan L3-S1 and save the 2-dimensional cross-sectional images in DICOM format, then input the DICOM files into Mimics 16.0 software to establish the 3-dimensional geometric model of L3-S1 in Mimics software, and to import the model into ANSYS 15.0 software after polishing and smoothing for meshing, so as to make the 3-dimensional finite element model. According to the anatomical position of each ligament, the normal 3-dimensional finite element model of L3 to L5 was established by adding the intervertebral disc, anterior longitudinal ligament, posterior longitudinal ligament, yellow ligament, interspinous ligament, supraspinal ligament, and intertransverse ligament.3.6The above-mentioned normal finite element model was applied with the same constraints and loads as the research on cadaver specimens in the literature, and the mobility in different directions was compared.3.7On the basis of the above L3 to S1 normal model which has passed the validation, the percutaneous endoscopic technique of lumbar spine is simulated. The tip, waist and base of L5 superior articular process were used as puncture points respectively to establish the precise puncture guidance route. The tail inclined 30° to the cephalic side and formed an angle of 30° with the coronal surface see Fig. .With the central and ventral side of L5 superior articular process as the puncture point, the same puncture guide route was established. Bone of different sizes  were removed along the guide line, and the different sizes of the articular process models were obtained see Fig. .3.8The inferior surface of the 3-dimensional finite element model with foraminoplasty was restrained by degrees of freedom. Different vertical loads were applied on the superior surface of L3 centrum to simulate the standing or sitting position of normal human body. The same pure torque was applied in the directions of flexion, extension, left and right bending, and left and right rotation, respectively, as in cadaveric specimens, with flexion, extension, left and right bending, and left and right rotation. Six kinds of motion states are loaded.3.9The stress and strain of normal model, 3 different parts of L5 superior articular process  and 3 different sizes of L5 superior articular process 7.5, 10, 12 mm) were analyzed and compared. Stress analysis , strain analysis . The entire procedure is shown in Table 0, 12 mm 3.10How to simulate the actual clinical state as real as possible with finite element model?Firstly, CT data collection should be as complete as possible, and thin CT scanning should be used to avoid data loss. The rough points on the geometric model reconstructed by CT should be treated as smoothly as possible. After importing the 3-dimensional geometric model into ANSYS software, the appropriate element type is selected for multi-grid generation as much as possible, which is convenient for later calculation. Reconstruction of ligament structure, articular capsule, articular surface, and intervertebral disc is the key to high simulation of the model. The starting and ending points, cross-sectional area, and articular capsule reconstruction of the ligament structure should be as close as possible to the anatomical position, and the accuracy should be ensured by repeated adjustments after loading. The definition of the release relationship of articular surface and friction coefficient should be defined by reference to classical literature. For sliding contact, the friction coefficient is 0.1. The reconstruction of intervertebral disc structure should include fibrosis, nucleus pulposus, cartilage endplate, and other anatomical structures. Each structure should be endowed with different material properties according to its characteristics, and ultimately validated.To simulate the operation of intervertebral foraminoplasty, different parts of the superior articular process of L5 were used as puncture points, and precise puncture guidance route was established. Cylindrical excision of the superior articular process of L5 was performed at the angle of 30° to coronal plane, respectively, to simulate the circumferential sawing of the articular process during the operation. According to the common position of the articular process and the size of the circular sawing, the resection site was defined. The resection diameters were 7.5, 10, and 12 mm for the tip, waist, and basal parts of L5 superior articular process, respectively.Knowing the best position and size of articular process under the premise of convenient for clinical operation.In the clinical operation of lumbar percutaneous endoscopy, the location and size of foraminoplasty vary from doctor to doctor or academic school, and there is no gold standard for operation. Doctors tend to pay more attention to the thoroughness of decompression or the convenience of manipulation, but they do not pay much attention to the location or size of the facet formation, and there will be less research on the impact of lumbar biomechanics in the future.Through this study, we can determine which or which sites of foraminoplasty have less influence on the biomechanics and mobility of this segment or adjacent segments. The size of foraminoplasty is not only easy to operate, but also has the minimal impact on the structure of the spine. The clarity of these problems is of great significance for the standardization and unification of lateral lumbar percutaneous endoscopy technique in the future, so as to facilitate the popularization and development of this technique for the benefit of more patients.3.11The investigators and research assistants in the study team will collect the data and enter them directly into the electronic-Case Record Form. The data will be securely stored, with specific access rights granted to members of the study team according to their role in the study. Participants, healthcare professionals, the public, and other relevant groups could get the results of the trial as soon as we complete the trial and publish our achievements.3.12Any observed side effects related to radiation exposure will be documented throughout the trial period and reported to the sponsor without delay. These data will be provided for periodical review by the Data and Safety Monitoring Board.4Lumbar is an important part of human activity and stress-bearing. It has deep location, complex anatomical structure, and adjacent relationship, and has important physiological functions. The mechanical research of this area has been an important subject in orthopedics field. The finite element method studies the stress and strain of the relevant region by meshing, constraining, and loading the model. This technology has been applied in medical field since 1960s. With the rapid development of computer technology, it has been applied more and more widely, and the simulation degree is getting higher and higher.However, the finite element model has made many simplifications and assumptions in the process of modeling, so the extent to which the established model can be simulated is a problem that researchers must consider. In order to ensure the accuracy of the follow-up study, the validity of the finite element model must be verified before further application.Since Professor Hooggland of Germany put forward the technique of “foraminoplasty” in PELD in 2002, percutaneous endoscopy of lumbar has made rapid progress in recent decades. Because of the improvement of doctors’ operation technology and the advancement of surgical instruments, the indications of operation are becoming more and more widespread. With the continuous development of this technology, different technical schools emerge at the historic moment, and there is often a lack of uniform or relatively standardized operating standards in the clinical operation process. Clinicians often pay more attention to how to achieve more thorough decompression, as well as the convenience and safety of operation, while less attention is paid to the trauma caused by technology itself or the biomechanics of spine after technology. Therefore, we often do not know the trend of spinal degeneration and the long-term clinical manifestations while achieving better short-term clinical efficacy.At present, in spinal surgery, although the research of lumbar finite element analysis has been widely and deeply carried out, it mainly focuses on:1.stress and strain analysis of different internal fixation devices, to find the area of stress concentration for improvement or better prevention of failure of internal fixation devices2.the biomechanical effects of different internal fixation methods were analyzed in order to select more suitable internal fixation methodsFew studies have focused on changes in stress and mobility of the disc and facet joints at or near the lumbar segment after foraminoplasty at different sites or foraminoplasty of different sizes during percutaneous endoscopic lumbar surgery.This trial will take L4/5 segment as an example to study the effects of foraminoplasty on the stress changes of L4/5 and adjacent L3/4, L5/S1 intervertebral discs, facet joints, and the motion changes of each segment in different regions of L5 superior articular process  and sizes , so as to provide a reference for lateral lumbar percutaneous endoscopy. It can provide detailed and exact biomechanical evidence and supply corresponding mechanical basis for further standardization of its operation, so as to make the technology better benefit the vast number of patients.Yizhou Xie, Wang Xinling, Yang Yu, Xiaohong Fan, and Weidong Wu performed the experiments. Yizhou Xie, Xinling Wang, and Yang Yu wrote the paper. Yizhou Xie, Yang Yu, Xiaohong Fan, Dangwei Gu, Weidong Wu, and Qiang Jian reviewed and edited the manuscript. All authors read and approved the manuscript.YY and XFcontributed equally to this work and should considered as corresponding authors.


To compare the impact of two fast-track strategies regarding the extubation time and removal of invasive mechanical ventilation in adults after cardiac surgery on clinical and hospital outcomes.This was a retrospective cohort study with patients undergoing cardiac surgery. Patients were classified according to the extubation time as the Control Group , Group 1 (extubated in the operating room after surgery) and Group 2 (extubated within 6 hours after admission to the intensive care unit). The primary outcomes analyzed were vital capacity on the first postoperative day, length of hospital stay, and length of stay in the intensive care unit. The secondary outcomes were reintubation, hospital-acquired pneumonia, sepsis, and death.For the 223 patients evaluated, the vital capacity was lower in Groups 1 and 2 compared to the Control . The length of stay in the intensive care unit was significantly lower in Groups 1 and 2 compared to the Control , whereas the length of hospital stay was lower in Group 1 compared to the Control (p = 0.014). There was an association between extubation in the operating room (Group 1) with reintubation (p = 0.025) and postoperative complications (p = 0.038).Patients undergoing fast-track management with extubation within 6 hours had shorter stays in the intensive care unit without increasing postoperative complications and death. Patients extubated in the operating room had a shorter hospital stay and a shorter stay in the intensive care unit but showed an increase in the frequency of reintubation and postoperative complications. In addition, some studies have shown that the procedure does not increase the risk of postoperative complications, mortality or reintubation rates.,5-8The concept of fast-track management in cardiac surgery is associated with the use of anesthetic drugs that allow the rapid discontinuation of mechanical ventilation in the postoperative period of patients undergoing cardiac surgery. Some studies have established a fast-track criterion for endotracheal tube (ETT) removal within 12, 10, 9, 8,-14 6,-17 7, 4 or 2 hours after the surgery, with the patient in the ICU. In contrast, other protocols recommend the removal of the ETT while in the operating room, between 5 and 30 minutes after the surgery.,21 This approach is called ultra-fast track.However, there is no standard definition of the fast-track strategy. Short-acting opioids are used in low doses to extubate the patient within a certain time, and this time is chosen arbitrarily by the surgical team because there are no physiological or pathological factors available to determine this time frame.There is little consistent data regarding the changes in lung mechanics and function in the postoperative period of fast-track cardiac surgery. Furthermore, it is important to more accurately assess the effects on lung mechanics and function, occurrence of reintubation, incidence of postoperative complications, length of ICU stay, and length of hospital stay in the different time intervals included in the fast-track concept to determine which extubation strategy promotes the best recovery of patients undergoing cardiac surgery.The objective of this study was to evaluate the impact of fast-track management in the postoperative period of adult cardiac surgery on clinical and hospital outcomes at two different time points of ETT removal compared to a control group.Real Hospital Português de Beneficência located in Pernambuco. It was approved by the Human Research Ethics Committee of the Hospital Agamenon Magalhães under opinion 475,522.This was a retrospective cohort study conducted by collecting data from the medical records of patients admitted from March 2013 to June 2013 to the All patients undergoing cardiac surgery, aged between 20 and 80 years, extubated in the operating room or who remained under invasive mechanical ventilation for a period of up to 18 hours after admission to the ICU were included in the study.Patients with surgical incisions other than sternotomy, history of thoracic surgery in the past year, need for intra-aortic balloon pump or extracorporeal membrane oxygenation, or with liver disease or chronic obstructive pulmonary disease were excluded.The patients included were stratified into two groups of early extubation (fast-track) according to the time of ETT removal and a Control Group (CG). The CG was composed of patients who, despite undergoing similar anesthetic procedures as the other groups, were extubated after 6 hours from admission to the ICU, respecting the time limit of 18 hours. Group 1 (G1) consisted of patients undergoing ultra-fast track, with extubation occurring in the operating room 5 to 30 minutes after the end of surgery. Group 2 (G2) comprised patients extubated within 6 hours after admission to the ICU. The primary outcomes analyzed were vital capacity (VC) on the first postoperative day , length of ICU stay (days) and length of hospital stay (days). The secondary outcomes analyzed were reintubation , hospital-acquired pneumonia (HAP), sepsis, and death. HAP is defined as pneumonia that occurs 48 hours or more after hospital admission, and notification is made after medical diagnosis. The diagnosis of sepsis was made according to the hospital's protocol which defines it as an increase of two or more points on the Sequential Organ Failure Assessment (SOFA) after 24 hours.The following data were collected: age, gender, body mass index (BMI), type of surgery, and mortality risk for cardiac surgery according to the European System for Cardiac Operative Risk Evaluation II (EuroSCORE).The choice for fast track, as well as the selection of the time for ETT removal, was based on specific protocols of the surgical team and sedation depth. Anesthetic induction was similar in all three groups, using propofol, etomidate or thiopental, supplemented with midazolam, fentanyl or remifentanil; anesthesia was maintained with propofol or inhalational anesthetic (sevoflurane). Pancuronium or rocuronium was used for neuromuscular blockade. Thus, certain surgical-anesthetic teams opted for extubation in the operating room, while others maintained anesthesia so that extubation of the patient occurred after arrival in the ICU.2O and a positive end expiratory pressure (PEEP) of 5cmH2O for 30 minutes. Following extubation, all patients underwent noninvasive ventilation in the bilevel positive airway pressure (BiPAP) mode with IPAP (inspiratory positive airway pressure) between 10 and 16cmH2O to maintain the tidal volume at 6mL/kg and the EPAP (expiratory positive airway pressure) at between 5 and 6cmH2O. The patients' VC, regardless of the extubation time, was evaluated on the first postoperative day, with all patients already breathing spontaneously. The team performed the procedure through spirometry to determine the appropriate lung expansion therapy for each patient.Patients who were going to be extubated in the ICU started the process of mechanical ventilation weaning after waking up. The spontaneous breathing trial was performed with the patient still under mechanical ventilation in pressure support mode with a pressure Delta of 7cmHStandard intra- and postoperative monitoring included monitoring of radial artery pressure, central venous pressure, electrocardiogram, temperature, and peripheral oxygen saturation. Postoperative pain was treated with morphine and dipyrone to reduce the impact of pain on the patient's lung function.Statistical analysis was performed using the Statistical Package for Social Science (SPSS) software, version 20.0, considering p ≤ 0.05 as the statistical significance threshold for all tests.The Kolmogorov-Smirnov test was performed to test the normality of the variables, followed by appropriate statistical treatment, according to the data distribution.Qualitative variables were expressed as absolute and relative frequencies. The chi-squared test was used to assess the association of categorical variables and the incidence of HAP, sepsis, reintubation, nonrespiratory complications, and death between groups.Normal quantitative variables were expressed as the mean ± standard deviation, and nonnormal variables were expressed as median and interquartile range (IQ) (25 - 75). The Kruskal-Wallis test with the post hoc t-test was used to characterize the sample and to analyze the VC variables, whereas the Kruskal-Wallis test with the post hoc Mann-Whitney test was used to analyze the lengths of ICU and hospital stay.A total of 223 patients grouped in G1 (n = 48), G2 (n = 78), and CG (n = 97) were included in the study, with a mean total time of ETT and total mechanical ventilation, from surgery to extubation, of 4 hours and 12 minutes, 8 hours and 43 minutes, and 15 hours and 48 minutes, respectively. Most patients were male, with a mean age of 57.45 years and overweight on average (27.61kg/m²). The stratification of mortality risk after cardiac surgery was evaluated by the EuroSCORE, with 88.1% of patients classified as low risk (zero - 2 points), 20% as medium risk (3 - 5 points) and 2.8% as high risk (> 6 points), with no difference between groups, as shown in There was also an association between the group profiles and the occurrence of nonrespiratory complications. G1 exhibited the highest frequency of complications, with 14.6% of cases due to cardiac tamponade (4), mediastinitis (1), pulmonary hypertension (1) or partial intestinal obstruction (1). In G2, the main complications were cardiac tamponade (1), acute renal failure (3), and pulmonary hypertension (1). The CG had the lowest frequency (3.2%) of complications, including acute renal failure (1), mediastinitis (1), and pulmonary hypertension (1).There was no difference between the groups regarding the occurrence of HAP, sepsis, or number of deaths .The VC on the first postoperative day and the length of ICU/hospital stay showed a significant difference between the groups . The VC was significantly lower for G1  and G2  compared to the CG (21.03 ± 6.75), without significant differences between G1 and G2. The length of ICU stay was significantly lower in G1 compared to the CG (p = 0.009), with a median and IQ (25 - 75) of 1 (1 - 3) and 2 (1 - 4), respectively. The length of ICU stay was also lower in G2, with a median IQ (25 - 75) of 1 (1 - 2.25), compared to the CG (p = 0.000), and there was no difference between G1 and G2. Regarding the length of hospital stay, only G1 was significantly lower when compared to the CG (p = 0.014), with a median IQ (25 - 75) of 6 (5 - 7) and 7 (6 - 9), respectively. There was no difference in the length of hospital stay between G2, 6 (6 - 7), and the other groups .,23,24In cardiac surgery, patients conventionally receive anesthesia using high doses of opioids and would, consequently, be under invasive mechanical ventilation for a long period of time. In the early 1990s, the concept of fast-track procedures, which involves the use of low doses of opioids for achieving rapid extubation, was introduced to meet the growing demand for cardiac surgery. Currently, many surgical teams use an anesthesia protocol that involves the removal of the ETT in the operating room or within a few hours after the end of surgery.Many studies have demonstrated the benefits of using fast-track protocols in cardiac surgery. More recently, a systematic review of 28 clinical trials showed that fast-track management reduces the length of ICU stay without impacting mortality, postoperative complications , or reintubation within 24 hours when compared to the conventional protocol.Such evidence is in accordance with the results of this study regarding the analysis between G2 and CG. There was no difference in mortality, occurrence of postoperative complications, reintubation, HAP, sepsis, or length of hospital stay between these groups, but there was a reduction in the length of ICU stay in G2 when compared to the CG., the systematic review revealed heterogeneity in the protocols of the studies included in the analysis, especially regarding the choice of time for ETT removal, grouping patients extubated in the operating room with patients extubated within 8 hours after their admission to the ICU. In our study, the analysis stratified patients according to the extubation time and identified some divergences from the previous investigation when analyzing the patients in G1 and the CG.However, despite the recent evidence on the fast-track strategy presented by Wong et al. in a study where patients extubated in the operating room had a significantly higher incidence of reintubation (8%) compared to patients extubated in the ICU, and all cases were due to respiratory depression. The same study found a higher incidence of postoperative complications in the ultra-fast track group, but without statistical significance.We found an association between the ultra-fast track protocol and the reintubation rate due to failure in the ETT removal. There were two (4.2%) cases of reintubation in G1 due to respiratory depression caused by residual narcosis. In addition, there was an association between the ultra-fast track and the occurrence of postoperative complications not related to the respiratory system. A similar result was also described by Montes et al., our study showed a reduction in both the length of hospital stay and the length of ICU stay in G1 compared to the CG. Both clinical outcomes are important and desired because they reduce hospital costs and public health expenditures. Corroborating our findings, the studies performed by Cheng et al. and Michalopoulos et al. showed a reduction in the length of hospital stay with an early extubation protocol and, more specifically, the study conducted by Saad et al. showed a shorter length of ICU stay in patients undergoing extubation in the operating room.In contrast to the results found by Montes et al. who reported that the lower the severity indices, the lower the possibility of death in this population.Despite the association found for postoperative complications and reintubations in G1, there was no difference in mortality compared to the GC and G2. The low mortality rate found in the three groups is probably related to the low EuroSCORE of the population, as described by Shoji et al., noted that VC values lower than 25mL/kg predispose patients to the appearance of atelectasis and respiratory complications, and our results showed no difference in the occurrence of HAP between the groups.The occurrence of reduced VC is common in the postoperative period of cardiac surgery due to a number of factors that include the surgical procedure itself, the use and time of extracorporeal circulation, sternotomy, and postoperative pain. Our results revealed a lower VC on the first postoperative day in the two fast-track groups when compared to the CG. However, this difference has little clinical impact because, in all cases, the VC had values below 25mL/kg, which reflects low lung expansion, capable of generating atelectasis and favoring the occurrence of respiratory complications. Pinheiro et al.This study had some limitations. Because it is a retrospective study based on the collection of data from medical records, there was no control regarding sample selection or randomization in the stratification of the groups, and the baseline characteristics of the patients could have influenced the results. It was also not possible to collect data on the time of extracorporeal circulation and the VC in the preoperative period because that is not a routine protocol in the hospital studied. Thus, evaluating the reduction in the VC based on individual baseline values was impossible. In addition, although there was no difference between the fast-track and control groups, the low EuroSCORE may have influenced the low incidence of the evaluated outcomes .Additionally, the lack of description in the medical records of an ultra-fast track operating room protocol can be indicative of a lack of standardization for the tracheal extubation procedure in this group of patients and, consequently, of a possible bias in the results. Thus, the results of the group that underwent such procedure should be evaluated with caution.This study demonstrated that in our sample the fast-track protocol with endotracheal tube removal in the intensive care unit is associated with a shorter stay in the intensive care unit without increasing the occurrence of postoperative complications, hospital-acquired pneumonia, sepsis, reintubations, or death compared with the conventional protocol. In turn, the ultra-fast track protocol reduces the length of stay in both the hospital and the intensive care unit; however, extubation of the patient in the operating room is associated with an increased occurrence of reintubation and postoperative complications.The external validity of our results is limited, and therefore we emphasize that other studies should be conducted to determine the ideal time for removal of the endotracheal tube after cardiac surgery.


Scientific Reports 10.1038/s41598-020-59910-7, published online 24 Fabruary 2020Correction to: In the original version of this Article the author Erika Barbara Abreu Fonseca Thomaz, was incorrectly given as Erika Barbara Thomaz. This has now been corrected in the PDF and HTML versions of the Article, and in the accompanying Supplementary Information file.As a result, in the Author Contributions statement“All authors  have made substantial contributions to all of the following: (1) the conception and design of the study, or acquisition of data, or analysis and interpretation of data, (2) drafting the article or revising it critically for important intellectual content, (3) final approval of the version to be submitted.”now reads:“All authors  have made substantial contributions to all of the following: (1) the conception and design of the study, or acquisition of data, or analysis and interpretation of data, (2) drafting the article or revising it critically for important intellectual content, (3) final approval of the version to be submitted.”