The FTIR spectra of the fouled RO membranes suggested that the constituents of the fouled material included aliphatic and aromatic compounds.In this work, three different types of Reverse Osmosis (RO) (Thin-Film Composite (SE), Cellulose Acetate (CE), and Polyamide (AD)) were used to perform foulant analysis (autopsy) study on the deposited materials from three different simulated brackish surface feed waters. The brackish surface water qualities represented the water quality in Iraqi marshes. The main foulants from the simulated feed waters were characterized by using Scanning Electron Microscope (SEM) images and Energy-Dispersive X-ray Spectroscopy (EDXS) spectra. The effect of feed water temperatures (37 °C and 11 °C) on the formation of the fouled material deposited on the membrane surface was examined in this study. Also, pretreatment by a 0.1 micron microfiltration (MF) membrane of the simulated feed water in advance of the RO membrane on the precipitated material on the membrane surface was investigated. Finally, Fourier Transform Infrared Spectroscopy (FTIR) analysis was used to identify the functional groups of the organic matter deposited on the RO membrane surfaces. The SEM images and EDSX spectra suggested that the fouled material was mainly organic matter, and the major crystal deposited on the RO membrane was calcium carbonate (CaCO Membrane fouling reduces water (flux) transport across a unit area of membrane that is caused by feed water particles’ deposition on the membrane surface or in its pores in a way that degrades the membrane’s performance ,2. FouliRO membrane fouling has been extensively studied to gain a better understanding of the fouling layer formation and morphology. The most common tools used in fouling layer investigation and providing morphological images are the scanning electron microscope (SEM), which is used to directly observe the fouling morphology, and the atomic force microscope (AFM), which is used to measure the roughness of the membrane surface and the change of fouling layers . To obta2, 16% clay, 13% organic matter, 6% CaSiO3, 3% Fe3O4, 3% AlPO4, and 3% CaSO4. Further, Koyuncu and Wiesner [3) and calcium sulfate (CaSO4) were the common salts precipitated on the membranes. Furthermore, their study showed that a variation in organic matter concentration can change the crystal morphology of calcium carbonate and, hence, increase its precipitation on a reverse osmosis membrane.Chu and Li , for ins2) [Phragmites australis), reed mace (Typha angustifolia), giant reed (Arundo donax), and papyrus (Cyperus papyrus), which are the most common vegetation in these marshes [The Iraqi marshes, located in the south, extend through a large area  . These m2) ,15. Due 2) . Recentl2) . The TOC marshes ,16,18.The main objectives of this study are: (1) to diagnose the main foulants from different simulated brackish surface feed waters, which represent three water analyses in the Iraqi marshes, on the three types of the RO membranes ; (2) to examine the effect of the feed water temperatures (37 °C and 11 °C) and, using a 0.1 µm MF membrane pretreatment unit, to pretreat the feed water before running it through the RO system on the morphology of the fouled materials deposited on the RO membrane surfaces; and (3) to identify the functional groups of the organic matter deposited on the RO membrane surfaces.Experiments were conducted in a commercial bench-scale cross-flow filtration unit, a stainless steel SEPA CF Membrane Element Cell . The SEPA CF Membrane Cell is designed to handle a maximum pressure of 6895 kPa and to accommodate a 19.1 cm × 14 cm flat sheet membrane. A 48-L batch of prepared brackish surface feed water was pumped at a constant flow rate of 2.27 Lpm from the feed tank through a 1-µm filter cartridge to the break tank using low pressure feed pumps . Then the feed water was pumped at the same flow rate through the RO membrane filtration cell using a high-pressure pump . The system pressure was kept in the range of 2620–2757 kPa using two high pressure needle valves. A schematic diagram of the experimental system is shown in 3 will precipitate. However, SI values at 11 °C were mostly less than 0 which indicates that the solution is under-saturated and CaCO3 will dissolve [Three different simulated water qualities that represented three brackish surface water analyses in the Iraqi marshes were used as feed waters to implement the experiments. These water analyses were reported by UNEP  and desidissolve . Additiodissolve .A total of 24 runs was carried out by repeating the same experimental procedures that are described elsewhere . In addi−1) on the fouled membranes were taken to identify the organic matter present on the membrane surface.After achieving the required water recovery for each experiment, the fouled membrane was gently removed from the cell. A Zeiss NEON high resolution scanning electron microscope (SEM) operating at 10 kV, equipped with energy-dispersive X-ray spectroscopy (EDXS) and secondary ion beam (FIB) , was used to directly observe the fouling materials deposited on the surface of the RO membrane. Samples from the unused membranes and different fouled membranes were cautiously cut to preserve the original biomass composition of the material in its original deposited condition. Then, the samples were sputter-coated with iridium (Ir) prior to the SEM imaging. In general, for most of the runs, two spectra were taken to show the variation of the morphology of the scale formation on the surface of the RO membranes. In addition, Fourier Transform Infrared spectroscopy (FTIR)  spectrum  membrane had a very smooth morphology, as shown in +, Ca2+, Mg2+, and Cl− were present in the spectrum. The data suggest that the fouling was due to a combination of organic matter and inorganic material. Although Fe was observed in the feed water in low quantity, it was probably due to a leaching from the system parts. For example, some rust was seen on the submerged part of the heated immersion circulator indicating a leach of iron into the feed water. In addition, although it was not found in the feed water, Ni was also detected by the EDSX spectrum. It was apparently due to the rust as well. The part that was rusting was replaced with an aluminum part to minimize the corrosion during the rest of the experiment runs.To investigate the difference in the scale morphology among the three types of the membranes , three SEM images of these membranes were taken after the membranes were operated under identical conditions . First, 2+ (38.1%) was present. Spectrum 9, which was located on the amorphous shape, shows that a lower level of Ca2+ (4.8%) was present. Both spectra show high levels of C and O. Moreover, spectrum 9 also shows a high level of Fe2+ (26.3%). The high peaks of O, C, and Ca2+ that exist in spectrum 8 suggest that the structure of the deposited material was calcium carbonate (CaCO3), which is consistent with that observed by Tzotzi [However, the deposited material on the CE membrane surface (run 3) mostly covered the membrane surface with a crystal structure (flowers) and lesser amounts of amorphous shapes, as illustrated in y Tzotzi  on a thiy Tzotzi . Therefoy Tzotzi ,23.2+ (27.3%) compared to a lower level of Ca2+ (1.8%) on the amorphous shaped material, as shown by spectrum 5. Likewise, both spectra (5 and 9) show a high level of C and O as well as a high level of Fe2+ on the amorphous shaped material. In addition, spectrum 5 shows a low level of silica present in the deposited material, and spectrum 6 shows a high peak of Cl− on the crystal shape. The SEM image and the data of spectra 5 and 6 suggest that the fouling materials deposited on the AD membrane surface have different configurations and composition. The fouling materials included different crystal shapes and a mixture of organic and inorganic matter. As a result of high levels of O, C and Ca2+, the large crystal form is also possibly due to the formation of CaCO3, which was reported as a common scale with all feed types by Greenlee [Greenlee .3 seen in 3 is likely a calcite crystal form, as suggested by Koyuncu and Wiesner [3 crystal in the cake formation. Moreover, Koyuncu [2, 0.481–0.314 Lpm/m2 and 0.467–0.325 Lpm/m2, respectively. The corresponding total time of these permeate fluxes of SE, CE, and AD membranes to achieve 70% of water recovery was 75.4 h, 80.8 h, and 85.6 h, respectively. The permeate productivity of the SE membrane (run 1) was significantly higher than that of CE (run 3) and AD (run 5) membranes. However, the salt rejection of the SE membrane (98.7%) is lower than that of the AD membrane (99.3%), but higher than that of the CE membrane (97.5%). This indicates that the salt rejection of the membrane was also affected by the surface roughness and the material of the membrane itself.The flower crystals of CaCO Wiesner . Further Koyuncu  proposed Koyuncu  reported Koyuncu ,26. Ther3, while the morphology is a sludge-like deposit on the membrane surface of run 4. It is obvious that low temperature (11 °C) affected the deposited material on the CE membrane and resulted in the sludge layer. Jawor and Hoek [−, Zn, Na+ and Ca2+, and a small amount of P, Mg2+, and S were present in the scale formation. The results suggest that the scale formation on the CE membrane surface of run 4 is mostly organic or carbonaceous matter, which can be attributed to the high levels of TOC and carbonate of the feed water, and is accompanied by inorganic materials. It can be assumed that the higher total permeate flux drop of run 4 (42.8%), which was calculated after completion of the run, compared to that of run 3 (34.7%), is a consequence of the blockage of the CE membrane surface because of the sludge layer formation.The effect of feed water temperature on the formation of the fouling material deposited on the membrane surface was also examined in this study. The SEM images in and Hoek  reported2+, indicating that the formed crystal on the membrane surface is likely CaCO3. The relatively low TOC and high Ca2+ (77.4–82 mg/L) and carbonate (73–94.2 mg/L) concentrations in feed water in location 1 apparently resulted in the uniform crystal shapes of CaCO3. This observation is consistent with the findings noted by Koyuncu and Wiesner [In lower TOC feed water (1.4–2.3 mg/L), the effect of the temperature on the morphology of the deposited material on the membrane surface is not the same as the one seen in the high TOC feed water (4.6–4.8 mg/L). The SEM images of the fouled SE membrane of run 13 and run 14 shown in 2+ in addition to the high peaks of O and C on the fouled membrane surface of run 20, which indicates that most of the crystal morphology is CaCO3. Also, the EDSX spectra shows that the fouling of run 19 and run 20 have a combination of organic matter and inorganic material. In addition, Inductively Coupled Plasma (ICP) spectrometer analysis showed that the Ca2+ concentration of the permeate at low temperature (run 20) was higher than that at high temperature (run 19), as shown in 2+ concentration is a consequence of more calcium deposits on the SE membrane surface, which resulted in forming more crystal morphology like CaCO3.Moreover, the SEM images of the deposited material from the feed water in location 5 at the temperature of 37 °C (run 19) and 11 °C (run 20), are shown in 3. Again, the low TOC and high carbonate concentrations of the feed water in location 5 were likely the main reason behind the formation of the CaCO3 crystals. This observation agrees with that found by Koyuncu and Wiesner [In addition,  Wiesner . ContradOverall, the results of the SEM images and EDSX spectra of the previously discussed runs revealed that the selected RO membranes have high rejection of organic matter, carbonate, and calcium, were also observed by Koyuncu , Koyuncu4 precipitated on the membrane surface. The low levels of precipitated sulfate are due to the high rejection of the RO membranes in favor of the carbonate that outcompetes the sulfate ion, as interpreted by Koyuncu and Wiesner [Another observation is that although the feed waters in locations 1 and 6 had high concentrations of sulfate , sulfur peaks were at very low levels, as shown in some of the spectra of the runs, indicating that some potentially low level of CaSO Wiesner . It is a2, compared to 0.716 Lpm/m2 for run 9 conducted with the MF membrane. Additionally, the formation of the fouled materials from the pretreated feed water by the MF membrane on the CE membrane surface (run 9) is apparently in clusters, and the EDSX spectrum of run 9, as shown in The effect of using a 0.1-micron MF membrane, which is considered the most appropriate method to remove larger particulates as a pretreatment unit for the feed water in advance of the RO membrane , on the 2+ was noticed in the cross section SEM image than in the plan view SEM image. Also, a high level of Ni and Fe was noted in the fouling layer. 2+ of the cross section SEM image was lower than that of the plan view SEM image , aliphatic alcohols , aromatic ethers (between 1300 and 1200 cm−1), aliphatic hydrocarbons , and inorganic carbonate  and lower amounts of olefins (between 3100 and 3000 cm−1).Several FTIR spectra from used RO membranes were done in this study. FTIR spectral interpretation of the absorption bands was provided by the software with the FTIR spectrometer, itself. Because the FTIR spectral interpretation for the absorption peaks present in the spectra of all runs is similar, only The results of the FTIR spectra suggest that the organic foulants contain humic substances  and polysaccharides due to C–O deformation ,11.−1, 1500 cm−1 and 820 cm−1. However, the FTIR spectrum of run 7 shows a main absorption near 3367 cm−1, which is due to the O–H stretches of the aliphatic alcohols and amides and a lower absorption near 1638 cm−1 due to aliphatic C=O deformation. The main absorption functional groups seen in the FTIR spectra of run 7 are also the main absorption functional groups seen in the FTIR spectra of the clean SE membrane, indicating less (than run 1) fouling material deposited on the membrane surface of run 7.Moreover, the FTIR spectra of the fouled SE membrane with and without using an MF membrane as a pretreatment unit for the feed water of run 7 and run 1, respectively, are shown in 3), while the formation of the deposited materials at the low temperature was a sludge-like deposit (mostly organic matter). On the contrary, the formation of the deposited materials from the low TDS and low TOC feed water on the surface of the RO membranes at the low temperature had more crystal shapes than that of the deposited materials at the high temperature.The SEM images and the EDSX spectra of the fouled RO membranes surfaces revealed that the distribution and the morphology of the deposited materials varied with the feed water quality, the RO membrane type, and the operational conditions, such as the feed water temperature. The scale formation on the RO membranes from the feed water of high TDS and high TOC almost covered the entire surface of the used RO membranes with a thick layer. However, the fouled material from the feed water of low TDS and low TOC partially covered the surface of the used RO membranes. Also, it was seen that, at a high temperature, the deposited materials from the high TDS and high TOC feed water on the RO membranes had crystal shapes (mostly CaCO3) was the predominant compound of the crystal formation present on the surface of several RO membranes. The results of the various configurations of the scale formations deposited under the same conditions on the three types  of the RO membranes indicated that the surface roughness and the material of the membrane itself affected the scale formation. Moreover, although the feed waters had high concentrations of sulfate, only low levels of CaSO4 precipitated on the membrane surface.The EDSX spectra of the scale formation on the surface of most of the fouled RO membranes showed a high level of C and O compared to the other elements recorded by the scan. This plus the absence or minimal amount of the inorganic cations indicated that the major foulant was the organic matter. In addition, calcium carbonate , on the SE membranes showed that the composition of the fouled material was about the same through the entire thickness. The average thickness of the fouling layer from high TDS high TOC (location 6), moderate TDS moderate TOC (location 1), and low TDS and low TOC (location 5) feed water was 8.5, 7.6 and 6.5 µm, respectively.The FTIR spectra of the fouled RO membranes showed that the main functional groups of the organic matter were aromatic hydrocarbons, aliphatic alcohols, aromatic ethers, aliphatic hydrocarbons, inorganic carbonate, and lower amounts of olefins.The thin-film composite RO membrane (SE) was the better performance type of the RO membrane;The total organic carbon (TOC) of the feed water may need to be treated;Based on the membrane process performance characteristics, the ultrafiltration membrane needs to be considered as an option to pretreat the feed water from these marshes before the RO membrane;Further studies are needed on a pilot scale or bench scale to produce process variables about using this type of membrane;A study on the overall economics and process of using the RO membrane technology in this area is needed.Based on this study, the following recommendations should be considered for implementing membrane treatment technology in the Iraqi marshes:


A muscle synergy is a coordinative structure of muscles that has been proposed as a strategy to reduce the number of variables that the central nervous system (CNS) has to address in motor tasks. In this article, the mechanical contribution of muscle synergies and coordinative structures of muscles in voluntary multi-directional postural control were investigated. The task for healthy, young subjects was to shift and align their center of pressure (COP) to targets dispersed in 12 different directions in the horizontal plane by leaning their bodies for 10 s. Electromyograms (EMGs) of 18 muscles and COPs were recorded in the experiment. Muscle synergies were extracted using non-negative matrix factorization (NMF), and the structure of coordinative modules to keep the posture leaning toward various directions was disclosed. Then the directional properties, such as the mechanical role , of muscle synergies and muscles were estimated using an electromyogram-weighted averaging (EWA) method, which is based on a cross-correlation between the fluctuations in the activation of muscle synergies and the COP. The results revealed that the ADs of muscle synergies were almost uniformly distributed in the task space in most of the subjects, which indicates that mechanical characteristics reduce the redundancy in postural control. In terms of the composition of muscle synergies and the ADs of individual muscles, we confirmed that muscle synergies in multi-directional postural control comprised a combination of several muscles, including various ADs, that generate torque at different joints. Humans maintain their bipedal standing posture by controlling their center of foot pressure (COP) to keep the projection of their center of mass on the ground within the base of support. In postural control during quiet standing, some studies have described human standing as a single inverted pendulum that pivots at the ankle joint  must address a huge amount of information if it needs to send neural orders to these muscles. For this reason, complex and flexible motor control is considered to be impossible  method has been utilized in previous studies  traces of muscles) and COP. Then, the ADs of muscles and muscle synergies were compared; the results confirmed that the ADs of muscle synergies were distributed in a well-balanced and compensated manner that cannot be covered by a single muscle.Nine young healthy male subjects volunteered for this experiment. Their mean (±SD) age, height and body mass were 24.0 (±1.3) years, 174.6 (±4.3) cm and 68.4 (±6.3) kg, respectively. None of the subjects had a history of any neurological disorder and their vision had been corrected to normal levels. All subjects provided written informed consent to participate in the study after receiving a detailed explanation of the purposes, potential benefits and risks associated with participation. The experimental procedures used in this study were performed in accordance with the Declaration of Helsinki and were approved by the Committee for Human Experimentation at the Graduate School of Human and Environmental Studies at Kyoto University .The basic procedure for the setup and measurement of postural sway during multi-directional postural control has been described in our previous study . The EMGs were recorded using Ag-AgCl electrodes with a diameter of 5 mm and an inter-electrode distance of 10 mm. To prevent cross-talk among neighboring muscles, a small inter-electrode distance was employed  for analysis of individual trials in which the COP trajectory was relatively constant. The COP data were filtered with a zero-phase-lag, fourth-order Butterworth bandpass filter from 5 Hz to 30 Hz to remove the effect of postural sway that is induced by voluntary contribution and non-physiological noise  was employed to extract muscle synergies from the data matrix of the EMGs (M) collected from each subject . ɛ is the residual of the reconstruction. The synergy weighting and activation coefficient matrices were normalized with the norm of muscle-weighting vector such that the individual muscle-weighting vector was a unit vector. To determine the number of muscle synergies N, cross-validation was employed. First, EMG data were shuffled across muscles and muscle synergies were extracted from 80% of the data. Second, the remaining 20% of the data was reconstructed by the muscle synergies obtained by the first procedure. The mean and SD of the variability accounted for (VAF) were obtained by repeating this operation 30 times, and the number of muscle synergies N was chosen based on the global VAF and muscle VAF. The former denotes the accuracy of the reconstruction of the whole EMGs (M), and the latter denotes the reconstruction of the EMG of each muscle. N was determined such that the global VAF exceeds 90% and the mean muscle VAF exceeds 80%. VAF was defined as 100× the coefficient of determination from the uncentered Pearson’s correlation coefficient  and the number of samples along a time series (5 blocks × 12 directions × 5 s × 100 samples), respectively.where r > 0.58; p < 0.01; Gentner et al., The similarity between any two synergies was measured by normalizing the synergy vectors (Euclidean norm) and computing their scalar product (EMGm(t) (t denotes a discrete time point) or activation of a synergy Cs(t); two COP components  were employed for cross-correlation. The EWA trajectories were calculated using the following equations:To determine the direction in which each muscle and muscle synergy were recruited to move the COP, the EWA method was employed , and the time-to-peak value ranged between 50 ms and 150 ms, that is, the COP fluctuations were reasonably attributed to activation of the muscle or muscle synergy considering electromechanical delay  global muscle synergies, which were extracted from the entire data set of five blocks across each subject. Figures The synergy W1 was primarily comprised of triceps surae muscles  and Gmed. It was activated when the subjects maintained the COP in the right anterior of the horizontal plane, and was similar among all subjects. The synergy W2 included TA, VL and Gmed. It was activated in maintaining the COP in the right posterior and was similar among Subject 2 and 3. The synergy W3, which was applied when the COP was held in the left posterior direction, comprised of TA and FL and was similar in Subject 1 and 2. The synergy W4 primarily mobilized FL, BFl, BFs and EDL, and was similar in Subject 2 and 6. It was activated when the COP was kept left anterior. The synergy W5 was dominated by the activation of ES and EDL, and was recruited in keeping the COP at relatively broad directions. It was similar in Subject 4 and 6. The synergy W6 consisted of BFl, BFs, ES and SOL, and was employed when the COP was kept left anterior. It was similar in Subject 1 and 4. The synergy W7, which included SOL, EDL and ES, was activated in maintaining COP leftward and was similar among Subject 4, 6, 7 and 8. The synergy W8 primarily activated VL and was recruited when the COP was kept posterior. It was similar in Subject 5 and 6. The synergy W9 consisted of the lower leg muscles  and Gmed. It was activated in maintaining the COP rightward; this result was similar in Subject 1, 3, 7 and 8. The synergy W10 recruited BFl and SM, and was activated in maintaining COP at left anterior. It was similar between Subject 3 and 7. The synergy W11 included FL and EDL. It was mainly activated in maintaining the COP in the left anterior and was similar among Subject 3 and 7. The synergy W12, which was applied when the COP was held in left anterior, was constructed by SOL and ES and was similar in Subject 7 and 8. The synergy W13 primarily mobilized RF and VL, and was similar in Subject 5 and 9. It was activated in broad conditions. The synergy W14 was dominated by the activation of TA, FL and EDL, and was recruited in keeping the COP at posterior. It was similar in Subject 8 and 9. The synergy W15 consisted of SM and ST, and was employed when the COP was kept anterior. It was similar in Subject 1 and 7. The remainder of the muscle synergies were subject-specific (Figure As a result of EWA, all muscles and muscle synergies exhibited statistically significant ADs Figures , 5, whicThe ADs of muscle synergies were distributed in various directions in most of the subjects Figures , 7. ThisThe objective of this research was to analyze the coordinating structures of muscles that contribute to voluntary postural control. Using NMF from the EMG dataset, 5.7 ± 1.80 muscle synergies were extracted and sorted according to cosine similarity. The ADs of the muscle synergies were estimated using the EWA method (Kutch et al., ADs of lower leg muscles tend to be distributed toward the anterior-posterior direction, as indicated by our previous study (Imagawa et al., The results indicate that a few muscle synergies were common among subjects; the synergy W1 was the only synergy that was similar among all subjects Figure . It tranFigure The majority of the extracted muscle synergies were composed of both lower leg muscles and thigh or trunk muscles and were related to the motion of the ankle, hip and knee joints. This finding indicates that voluntary control of the COP cannot be accomplished by the ankle even if angle changes in knee and hip joints are vanishingly small as compared to ankle joint angle changes; therefore, a mixture of several strategies is essential because numerous studies have revealed Kuo, . PreviouVoluntary and multi-directional postural control is one of the most basic motor tasks for humans; however, the manner in which muscles coordinate to bear force in various directions remains ambiguous. This study approached this question in terms of muscle synergies and their mechanical contribution in a multi-directional COP shift. The results indicated that ADs of muscle synergies were evenly distributed within the horizontal plane and that the reduction of redundancy in the musculoskeletal system works by combining muscles with different ADs and applying various strategies.AK, SH, TM and MK: conception and design of the experiments; AK, SH and BK: collection, analysis and interpretation of data; AK, SH and MK: drafts of the article or critical revisions for important intellectual content; AK, SH, BK, TM and MK: final approval of the version to be published.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Poly:poly(styrenesulfonate) (PEDOT:PSS) is among the most widely used polymers that are used as printed transparent electrodes for flexible Organic Electronic (OE) devices, such as Organic Photovoltaics (OPVs). The understanding of their optical properties and the correlation of the optical properties with their electronic properties and metallic-like behavior can lead to the optimization of their functionality as transparent electrodes in multilayer OE device architectures. In this work, we study the optical properties of different PEDOT:PSS formulations by non-destructive Spectroscopic Ellipsometry (SE), from the infrared to the far ultraviolet spectral regions. The optical response of PEDOT:PSS includes an intense optical absorption originated from the conductive part (PEDOT) at lower photon energies, whereas the electronic transition energies of the non-conductive PSS part have been measured at higher photon energies. Based on the different PEDOT:PSS formulations, the optical investigation revealed significant information on the relative contribution of conductive PEDOT and insulating PSS parts of the PEDOT:PSS formulation in the overall optical response, which can strongly impact the final device functionality and its optical transparency. The oligomer PEDOT segments are electrostatically attached on the PSS polymer chains ,29. The In this work, we investigate the optical and electronic properties of different PEDOT:PSS formulations with various compositions and ratios between its conductive (PEDOT) and insulating (PSS) parts, by non-destructive optical metrology in a wide spectral region, from the infrared (IR) to the far ultraviolet  range. The analysis of the measured optical properties of the different PEDOT:PSS formulations can provide significant information on the contribution of the conductive and insulating parts of PEDOT:PSS on its overall optical response. This information can contribute to the tuning of the overall optical transparency of organic electronic devices in which PEDOT:PSS can be implemented as a transparent electrode.−1) and NIR-Vis-fUV spectral regions (0.7–6.5 eV). The measured changes in the <Spectroscopic Ellipsometry is an effective, non-destructive method to determine the pseudodielectric function <al model ,31. The For the determination of the optical response of the PEDOT:PSS films, the measured <ε(ω)> has been modelled by a theoretical model to extract quantitative information on the electronic transitions of the material. This procedure includes the formulation of a theoretical model , and the fitting of the measured <ε(ω)> to this model by using the desired parameters as variables in the numerical analysis. The quality of the numerical analysis fit is determined by the calculation of the root mean square error parameter, which calculates the error value between the measured and theoretical Ψ and Δ values ,32.The optical properties of the PEDOT:PSS layer has been described by a combination of the Lorentz–Drude model for the conductive PEDOT and the Tauc Lorentz (TL) model ,32. The The structure and the morphology of these polymer nanomaterials strongly affect their conductivity. As it has been reported, the morphology of PEDOT:PSS consists of the PEDOT:PSS grain-like particles and of the excess of PSS, which is located at the grain boundaries and on the surface of the film, creating a polymer matrix ,17,24,28p and the Drude broadening. The plasma energy is relative to the free carrier density N, and it is described by the relation [0 is the absolute permittivity, m* is the effective carrier mass, and e is the electric charge. The calculated plasma energy values are found to increase in the case of the conductive PEDOT:PSS formulations , starting from 0.65 eV for the PVPCH8000 formulation, to 1.96 eV for the PH1000 formulation. On the contrary, the Drude broadening term that is related to the long-range order of the material reduces from 1.49 for the PVPCH8000 formulation to 0.47 for the PH1000 formulation. Therefore, the conductive PEDOT:PSS formulations are characterized by a higher number of charge carriers.relation ,31:(1)ωD (=ħ/τD), which is the inverse of the relaxation time τD, and depends on the phonon contribution and on microstructural properties of the material, that include static impurities, defect density, grain boundary, grain size etc. As it can be seen from D values are reduced for the case of the more conductive PEDOT:PSS formulations, leading to higher relaxation times of the charge carriers, which are influenced by the existence of grain boundaries, and structural defects within the PEDOT:PSS structure [The above are justified by the study of the broadening parameter (or damping factor) Γtructure ,35.The enhancement of the carrier mobility is mainly attributed to the delocalization of charge carriers, which is correlated to the increase in packing density of the PEDOT:PSS nanoparticles, due to the reduction of the excess PSS . This reThe PEDOT:PSS films are commercially available as an aqueous colloidal solution, whereas during the casting of PEDOT:PSS films from solution, their structure is maintained in the film. In this work, thin films of PEDOT:PSS were drop-casted on quartz glass substrates, and the thickness of the drop-casted PEDOT:PSS layers was ~3 μm. After the coating, the samples were heated for 90 s at 100 °C in order to remove the solvent.−3–10−4 S/cm and 10−5 S/cm, respectively, and they are used as hole injection layers in OE devices [oc of OPVs through the reduction of the dark current of the OPV device [Five different aqueous dispersions of commercially supplied PEDOT:PSS materials obtained from Heraeus were used. These formulations are the Clevios PH1000 (1:2.5), PH500 (1:2.5), PHCV4 (1:2.5), Al4083 1:6), and PVPCH8000 (1:20). These PEDOT:PSS formulations have been used as transparent electrodes in several OE devices, such as OPVs and OLEDs , and PVP,39,40,41 devices ,25,38,43V device ,38. −1) and by a Phase Modulated Spectroscopic Ellipsometer (Horiba Jobin-Yvon) working at the near IR-visible-far ultraviolet spectral region (0.7–6.5 eV). The setup of the FTIRSE system has been described in detail elsewhere [The optical and electronic properties were measured by the use of non-destructive Spectroscopic Ellipsometry (SE) in an extended spectral region by a Fourier Transform IR Spectroscopic Ellipsometer (FTIRSE) working on the IR spectral range  by using the following relation [For the calculation of the conductivity σ = 1/ρ where ρ is the resistivity, we have used the determined parameters from the Drude model analysis of the measured <relation ,47,48:. The tapping mode was utilized for better image acquisition, using rectangular Si cantilevers with a nominal tip curvature of 10 nm. Finally, the surface energy of the various PEDOT:PSS formulations were measured by contact angle (CA) technique, which were performed with an optical contact angle and surface tension meter CAM200 . The liquid was water, and the drop volume was 5 μL, with a surface tension of 72.8 mN mi et al. .In summary, we have investigated the metallic-like behavior of different PEDOT:PSS formulations by modelling their optical properties in the IR–fUV spectral region by the use of non-destructive SE. The PH1000, PH500, and PHCV4 formulations are characterized by higher metallic contribution at the IR photon energies as a result of the increased charge carrier density, and the higher ratio of the conductive PEDOT part in the material structure. In addition, we have determined the electric conductivity of the PEDOT:PSS formulations through the analysis of the optical properties by non-destructive SE measurements. This information can contribute to the understanding of the optical investigation of multilayered organic electronic devices in which PEDOT:PSS is used as an transparent electrode and buffer layer. This research also denotes the importance of optical metrology methods in the optimization of the printing processes for the fabrication of OE devices on flexible substrates.


Our results suggested that the structure of MMTD  is the main toxic functional group for embryo deformities; the 7-ACA  structure mainly affects motor nerve function; and both the MMTD and 7-ACA structures are responsible for cardiac effects. Impurity G (7-ACA) presented with the strongest toxicity; impurity A was most extensively absorbed to embryo and larvae; and impurity F (MMTD) exhibited the strongest apparent toxic effect; Therefore, impurities F and G should be monitored from the cefazolin sodium preparations.Cefazolin sodium is an essential drug that is widely used in clinical therapy for certain infective diseases caused by bacteria. As drug impurities are considered to be one of the most important causes of drug safety issues, we studied embryotoxicity, cardiotoxicity, and neurotoxicity of nine cefazolin sodium impurities in zebrafish embryo and larvae for the objective control of impurity profiling. LC-MS/MS was employed to analyze the compound absorbance  Cephalosporin has the characteristics of a wide-spectrum antibacterial drug, low toxicity, and resistance to penicillin enzymes. In addition, cephalosporin accounts for about 50% of the total sales of antibiotics in China; of this, 2% of the sales involve cefazolin sodium (unpublished data). A wide range of clinical applications has led to the continuous emergence of adverse drug reactions (ADRs) caused by cephalosporin. Fan et al. analyzed 1,169 cases of cephalosporin-induced ADRs that were reported from 1998 to 2010 in 958 publications in China by using the bibliometrics method: the most frequent were systemic reactions (35.67%) followed by central and peripheral nervous system reactions (19.76%), and the occurrence of blood abnormality (13.94%). The main clinical manifestations of ADRs were anaphylactic shock (28.14%), disulfiram-like reactions (12.74%), and hematuria (8.04%). Of the 1,169 cases, 118 (10.09%) were caused by cefazolin sodium Fan, . The famDrug impurities are considered to be one of the important causes of drug safety issues  were fed at the Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Beijing Union Medical College. All experimental protocols were approved by and performed in accordance with the Good Laboratory Practice regulations for non-clinical laboratory studies of drugs issued by the National Scientific and Technologic Committee of the People's Republic of China.Zebrafish (n = 30) that were incubated in the breeding water were the controls and each experiment was repeated at least three times. Anesthetic MS-222  was added to the larval solution to 0.016% final concentration and then the zebrafish bodies (30 each dish) were washed three times with deionized water, triturated in 100 μL of deionized water and followed a centrifugal separation; then the supernates were used for the measurement of the compounds in vivo. Values for the 10% teratogenic concentration (TD10), 50% teratogenic concentration (TD50) and 50% lethal concentration (LD50) were calculated using a Bliss algorithm.According to Zhang et al. , zebrafin = 30) were exposed to testing solution for 1 day, then the larvae with no obvious malformations were used for further analysis. The larvae were placed, respectively, in each micropore of a 48-well plate, with 8 in each group, for behavior to be detected by instrument of the ZEBRALAB , setting it to record every 10 s under specific conditions: (1) in the dark it continuously recorded for 20 min; and (2) under a bright/dark cycle (darkness for 5 min and light stimulation for 10 s) it recorded for 4 cycles. Untreated larvae were used as a normal control. The larvae swimming motions were observed and the distance and speed of movement were recorded and analyzed. Speeds lower than 0.2 cm/s were defined as inactive motion; speeds faster than 0.2 and lower than 4.0 cm/s were defined as medium-speed motion, and speeds >4.0 cm/s were defined as high-speed motion.According to Hu and Zhang , 5 dpf zAccording to Tong et al. , 2 dpf zin vivo in the 2 drug-administering durations.Drug contents in the embryos that were exposed to drugs from 6 hpf to 3 dpf were regarded as the absorption characterization of a drug in the zebrafish embryo toxicity test and in the cardiac toxicity test. The drug amount in the larvae exposed to drugs from 3 dpf to 5 dpf represented the absorption characterization of a drug in zebrafish neural toxicity. We then detected levels of the compounds The liquid chromatography system was a Prominence UFLCXR LC with autosampler , equipped with a CAPCELL PAK C18 MG S5 column (2.0 mm i.d. × 150 mm) . The mass spectrometer was an AB 6500 Q-Trap  equipped with electrospray ionization (ESI), operated in the positive ion or negative ion mode, and quantification was performed by multiple reaction monitoring (MRM) scanning modes. Mobile phase A contained 5 mmol/L of ammonium acetate solution and mobile phase B was acetonitrile. The temperature of the autosampler was set at 4°C and the column temperature was 30°C. Chromatographic conditions are shown in Table Before zebrafish collected, MS-222  was used for larval anesthesia, and then the zebrafish were washed three times with deionized water, collected in a tube (30 larvae each tube) and triturated with 100 μL of deionized water for 2 min. According to Zhang et al. , 10 μL oSeven-level standard solutions spiked into blank zebrafish homogenate were used to construct the calibration curves. The linear ranges of each compound are listed in Table The teratogenic rate, mortality, and abnormal phenotypes of the zebrafish caused by cefazolin and its impurities during embryo development are shown in Figure in vivo was analyzed as 50% of the embryos showed a toxic reaction. The toxic concentration of 50% (TD50) of impurity A was 1,000 times higher than impurity F. The in vivo drug concentration of impurity A was about 50 times higher than impurity F under TD50 concentration exposures, indicating that impurity F was more easily absorbed by the embryo than impurity A and its toxicity was about 50 times higher than impurity A. Similarly, the TD50 of impurity G was about 300 times greater than impurity F, but it's in vivo drug concentration was similar to impurity F, suggesting that “low toxicity” of impurity G in the embryo testing probably resulted from being less easily absorbed than impurity F. Based on Table 50 concentration exposures, the order of contents in vivo is impurity A > impurity F > impurity G, and the order of absorption capacity in vivo is impurity F > impurity A > impurity G in the group 1 impurities. The results indicated that the impurities F is more potent embryotoxins than other impurities and impurities G is clearly less potent than other impurities.Drug concentration The toxic reaction of the second groups of impurities was mainly teratogenic and their characteristic appearance was more or less like that of impurity G  and like that of the impurity A  suggesting the structures of 7-ACA and TAA as two different toxic functional groups work together in producing toxic reactions in this impurity group.50 of impurity H was about 3.5 times of impurity J, also its in vivo content was about 3.5 times as much as impurity J, suggesting that the absorption capacity of both were equivalent. The toxicity of impurity J was about 3.5 times as much as impurity H, which means the acetoxyl group at the 3-side chain of 7-ACA substituted by the methyl group slightly reduces the toxicity. The TD50 and drug in vivo content of impurity J and impurity G were both equivalent, so the 7-site of the 7-ACA connecting to TAA had no effect on the absorption. Because impurity I (cefazolin lactone) was easily hydrolyzed in an aqueous solution, it was not detected in vivo.The TDin vivo content of impurity K were very similar to impurity F, suggesting that the MMTD structure was the main teratogenic functional group for impurity K. The teratogenic effect of cefazolin (7R configuration) presented the typical impurity F phenotype  though they showed other differential abnormal phenotypes Table . The abn50 and in vivo content of impurities in zebrafish larvae are shown in Table 50 in Table 50 of the majority of the compounds in the 3 dpf groups was significantly lower than that of the 6 hpf groups; however, the in vivo drug concentration of the two groups were almost at the same level.No malformation was observed at every concentration of cefazolin and its impurities in the larval administration tests because the main organs of zebrafish are developed before 72 hpf  structure may be a major toxic function group that impacts the motor nerve function of zebrafish.For the first group of impurities, under dark conditions or under light/dark periodic stimulation, the time of larval active movement was shortened in impurity G in a concentration-dependent manner, and the larvae swimming velocity regularly increased at first and then decreased; while impurities A and F did not experience the same phenomena Figures . Analysiin vivo concentration of impurity H was about 10 times higher than that of impurity J, suggesting that the acetoxy group at the 3-side chain plays an important role in the active movement of zebrafish larvae. Further, compared with the results of impurity G (7-ACA), it can be implied that the combination of TAA with the 7-side chains of 7-ACA can decrease the impact on the locomotive nervous system of zebrafish larvae.In the second group of impurities, impurity I had no obvious effect on active movement time and the velocity of larvae under both conditions of dark environment and the periodic dark/light switch stimulation (data not shown). Because impurity I can be rapidly decomposed in an aqueous solution, its concentration in the body was not detected. Impurity J, under both dark conditions and periodic dark/light stimulus, resulted in a decreased time in larval active movements in a concentration-dependent manner, but its influence on speed was not obvious. Impurity H had just slightly increased active movement time of larvae in the absence of light stimulation conditions, its effect on speed was not obvious; while the active time and speed of larval movement in the periodic occulting stimulus had not been observed. Under the similarly treated concentrations, the in vivo concentrations, and their impact on the motor nerve system of zebrafish larvae are similar, too, which suggests the 7-side chain structure of cefazolin is not an important functional group for the nerve motor system of zebrafish larvae. In addition, impurity M and cefazolin are R/S isomers of each other, and the difference of the two compounds in concentration in vivo is about 10 times, suggesting that the spatial configuration of the 7-side chain of cephalosporin can influence the toxic effects of 7-ACA functional group by affecting in vivo absorption of the compounds. In summary, the neurotoxic effects of functional groups of cefazolins are mainly correlated to their mother nucleus structure of cephalosporin. The effects of impurities J and H (the acetoxy group at the 3-side chain of 7-ACA is substituted by the methyl group) on the motor nerve system of zebrafish larvae are different and the impacts of the two are also different from impurities M and N (containing the MMTD structure at the 3-side chain), suggesting that the 7-ACA mother nucleus and its 3-side chain jointly play a role on the motor nerve system of zebrafish larvae.With the third groups of impurities, in both the absence of light stimulation and periodic occulting stimulus conditions, impurities M and N could cause active time and speed of larval movement slightly increase at first and then decreased to the level of the normal control group (data not shown). However, cefazolin sodium significantly decreased the active movement time of larvae in a concentration-dependent manner, but the impact on the speed of movement was moderate Figure . ImpuritZebrafish embryos at 2 dpf were exposed to the testing solution for 1 day then the larvae with no obvious malformations were employed for heart rate recording. Comparing the influence of cefazolin and its impurities on the heart rates of the embryos Figure  and the in vivo concentration analysis of the impurities showed that impurities F and A were more easily absorbed than impurity G by the body ; while impurity F at 0.5 mmol/L led to a slowed heart rate of up to 50% or less of the normal control Figure . The in dy Table .Impurity H, I, and J showed no effect on embryonic heart rate at 30 mmol/L. At 60 mmol/L, for impurity H, the heart rate was reduced slightly, similar to 7-ACA, and the amplitude of the heartbeat was mildly lowered on the heart rate diagram Figure ; but impin vivo   Table . The groM) Table . The hea50 values, zebrafish embryos at 6 hpf are considered to be suitable for evaluating the embryonic toxicity of chemical drugs  structure was the toxic functional group of cefazolin sodium that caused embryo deformity of zebrafish. 7-ACA structure was the toxic functional group affecting the motor nerve function of zebrafish; the 7-ACA and 3-side chain structure play a role together on the motor nerve system of zebrafish larvae. MMTD and 7-ACA structures were responsible for the toxic cardiac function of cefazolin in zebrafish .in vivo in zebrafish and dealt data; YZ did the experiments of cefazolin and impurities on larval zebrafish motor behaviors and dealt data; JZ and YH did experiments of embryonic toxicity of zebrafish.CH and JZ conceived and designed the project, analyzed the data. BC, CH, and JZ wrote the manuscript. BC performed the experiments of cefazolin and impurities on the cardiac function of zebrafish and dealt the data; ZG and YL measured the concentrations The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Gag, as the major structural protein of HIV-1, is necessary for the assembly of the HIV-1 sphere shell. An in-depth understanding of its trafficking and polymerization is important for gaining further insights into the mechanisms of HIV-1 replication and the design of antiviral drugs. We developed a mathematical model to simulate two biophysical processes, specifically Gag monomer and dimer transport in the cytoplasm and the polymerization of monomers to form a hexamer underneath the plasma membrane. Using experimental data, an optimization approach was utilized to identify the model parameters, and the identifiability and sensitivity of these parameters were then analyzed. Using our model, we analyzed the weight of the pathways involved in the polymerization reactions and concluded that the predominant pathways for the formation of a hexamer might be the polymerization of two monomers to form a dimer, the polymerization of a dimer and a monomer to form a trimer, and the polymerization of two trimers to form a hexamer. We then deduced that the dimer and trimer intermediates might be crucial in hexamer formation. We also explored four theoretical combined methods for Gag suppression, and hypothesized that the N-terminal glycine residue of the MA domain of Gag might be a promising drug target. This work serves as a guide for future theoretical and experimental efforts aiming to understand HIV-1 Gag trafficking and polymerization, and might help accelerate the efficiency of anti-AIDS drug design. The human immunodeficiency virus (HIV-1) is a retrovirus that causes acquired immunodeficiency syndrome (AIDS), an infectious disease with high annual mortality. Gag protein is the major structural protein of HIV-1 and can self-assemble into the HIV-1 sphere shell. Therefore, an in-depth understanding of Gag protein trafficking and polymerization is important for gaining further insights into the mechanisms of HIV-1 replication and the design of antiviral drugs. Through mathematical modeling, optimization and quantitative analysis, we hypothesized the budding and release time of virus-like particles and revealed that the dimer and trimer intermediates might be crucial in hexamer formation. We also concluded that the predominant pathways in hexamer formation might be the polymerization of two monomers to form a dimer, the polymerization of a dimer and a monomer to form a trimer, and the polymerization of two trimers to form a hexamer. Our analysis also suggested that the N-terminal glycine residue of the MA domain of Gag might be a promising drug target. These results serve as a guide for further theoretical and experimental efforts aiming to understand HIV-1 Gag trafficking and polymerization and could aid anti-AIDS drug design. Gag protein (Gag) is the major structural polyprotein of HIV-1 and is synthesized in large amounts in the cytoplasm. Gag diffuses freely within the cytoplasm, hijacks the molecular motors, and moves along microtubules to the cytosolic side of the plasma membrane (PM) domain . UnderneIn the field of theoretical research, Liu et al.  first prA recent study on the events initiating HIV-1 Gag assembly was conducted by Kutluay et al. . These rTo the best of our knowledge, the reported models , 11–13 fThe transformation between monomers and dimers in the cytoplasm.The trafficking of monomers and dimers in the cytoplasm.The polymerization of monomers, dimers, trimers, tetramers, pentamers and hexamers of Gag underneath the PM.We first estimated the parameters of the model based on experiment data  and asseThis work will lead to a better understanding of the dynamics of Gag-Gag interaction and Gag trafficking, which are important in the emergence of HIV, and it might provide theoretical guidance for the design of antiretroviral drugs.This work aimed to assess the Gag trafficking in the cytoplasm and Gag polymerization underneath the PM. The schematic diagram used to develop the mathematical model is shown in A1 The cytoplasm is an annulus . Because s1 is close to zero, we concluded that Gag-G2A might fail to hijack the molecular motor.MA comprises the N-terminus of the Gag polyprotein, and it is responsible for targeting the Gag polyprotein to the PM. Therefore, mutation of the N-terminal glycine residue of MA to alanine (G2A) can reduce the attachment of a myristoyl group to Gag and impede its recruitment to the PM , 45. In tal data . The valThe comparison between the simulation values and the experimental data, which is shown in ki,j, two proportionality coefficients kD and ks and the transfer speed s1 of Gag-G2A. The constraints for the 13 parameters are as follows:In our study, we used eight data points for WT Gag and eight data points for Gag-G2A  to fit 1All 10 polymerization coefficients are positive.The two proportionality coefficients are between 0 and 1.μm/s.The transfer speed of Gag-G2A is less than 1 After the parameter values are optimized based on experimental data , we evalIn this work, we used this technology  to analyk11, k12, k23, kD and ks show a steep concave shape, indicating that the optimization route can rapidly reach the minimum. The profile likelihoods for k1, k15 and k24 also show a concave shape, however, the curves on the right side of the vertical dashed lines decrease slowly, indicating that their optimization routes might reach the minimum slowly. The profile likelihoods for k13, k14, k22, k33 and G2A − s1 have several local minima, hence, more iterations might be needed for the optimization route to jump out of and not get stuck at these local minima.The profile likelihoods of all the parameters are shown in s1, s2, ki,j are decreased compared with the corresponding values for WT Gag. These limiting conditions were included in the process of parameter optimization. The values of these parameters are listed in The CA is one of the four major domains of Gag and plays an important role in Gag multimerization and assembly at the PM. Furthermore, Gag: RNA binding is mediated by the CTD of the CA, which participates in Gag-Gag interactions. Thus, Gag-dCTD will show decreased on-rate constants. Furthermore, because the CA and MA of Gag are bound to each other, Gag-dCTD might show slightly impaired CA function. The damaged CA domain will slightly decrease the transport velocity of Gag, thus, the transport coefficient of Gag-dCTD might be slightly slower than that for WT Gag. This assumption is also supported by experimental data  for Gag-According to various references , 51, 52,In 2004, Briggs et al.  reportedJouvenet et al.  observedNG is the number of Gag proteins in a VLP, Np is the total puncta per cell in the budding state, p is the ratio of slowly appearing puncta, and R is the radius of a cell.Nermut et al. showed some pictures of VLPs in the budding state , and theNG = 2400, Np = 50, p = 74% and R = 10, the threshold surface density is 1.17 × 102ymol/um2. When Np is changed to 100 and 150, the threshold surface densities are 2.34 × 102ymol/um2 and 3.51 × 102ymol/um2, respectively.When SGag denotes the surface concentration of Gag, CGagi denotes the volume concentration of Gagi underneath the PM, and H is the thickness of the concentrated domain of Gag underneath the PM, which is set to 0.13 um [In our work, the surface density of Gag at the PM can be obtained by the following formula: 0.13 um .2, 2.34 × 102 and 3.51 × 102ymol/um2, respectively. The predicted budding and release times agree with earlier findings to some degree [When the surface density of Gag is equal to the threshold surface density, the cumulative time is estimated as the budding and release time. Times of 3.51, 8.53 and 21.34 hours are predicted for threshold surface densities 1.17 × 10e degree , indicatith model output variable Oi with respect to the jth parameter Pj at the time T, Si,j(T) asIn 2011, Tavener et al.  defined ith output variable Oi with respect to the parameter Pj, Ei,j(T) asThese researchers also defined the elasticity of the Elasticity is defined in terms of relative sensitivity and can describe the rate of change in the relative size of the output variables with respect to the relative size of the parameters. An elasticity analysis would thus yield more reliable results. This definition has an extraordinarily wide range of applications .Ei,j(T) was estimated as follows:Pj is a small perturbation of the parameter Pj. The elasticity values for all parameters corresponding to eight outputs, specifically the monomer and dimer concentrations in the cytoplasm and the concentrations of each of the polymers at the PM, are shown in Based on the literatures , 56, thek11 and k12 are greater than those for the other polymerization coefficients. This findings indicates that perturbations of these two parameters can lead to relatively large changes in Gag polymer concentrations. Therefore, we can conclude that the corresponding two reactions, which involve the polymerization of two monomers to form a dimer and the polymerization of a monomer and a dimer to form a trimer, might be key reactions. If future drugs can decrease the values of k11 and k12, concentrations of Gag high-order polymers will be significantly reduced.As shown in ks, which measures the ability of Gag to land on the PM by active transport. Therefore, we can conclude that this process has a very significant impact on Gag polymers on the PM. As a result, suppression of the Gag concentration on the PM by reducing the ability of Gag to stay on the PM might be a good strategy.Among all of parameters, the highest elasticity value is found for kD is found to be very small, which illustrates that the landing of Gag on the PM by diffusion has little impact on changes in the concentrations of Gag polymers on the PM. In addition, the elasticity value for the transport speed s1 of Gag-G2A is very small with a value close to zero. This finding further supports the hypothesis that Gag-G2A might hardly be able to hijack molecular motors to move to the PM, and as a result, Gag-G2A might be an important drug target.The elasticity value of Pk is the simultaneous perturbations of all parameters during the k-th perturbation. The global elasticity function values for 10% perturbations of all parameters are shown in The global elasticity function was defined as follows:The patterns underlying the formation of polymers constitute a very interesting topic , 58. UsiHexamer formation consists of three pathways:k24P2P4 − k′24P6 and k15P1P5 − k′15P6. The largest value among these rates corresponds to the predominant pathway. The values for these three pathways during the first 30 minutes are shown in Gag3 ⇌ Gag6. We also explored the predominant pathways in pentamer and tetramer formation. As illustrated in Gag2 + Gag3 ⇌ Gag5, and as shown in Gag + Gag3 ⇌ Gag4. We compared these three most important pathways and found that the trimer intermediate was needed in all three predominant pathways. Therefore, we conclude that the Gag trimer might be a key intermediate in hexamer formation.The rate equation for the hexamer concentration can be described as follows:Gag1 + Gag2 ⇌ Gag3 might be a key pathway. As shown in Gag3 ⇌ Gag6. Taken together, the key pathways for the formation of a hexamer from a monomer might be 2Gag1 ⇌ Gag2, Gag1 + Gag2 ⇌ Gag3 and 2Gag3 ⇌ Gag6, and the key intermediates in hexamer foramtion might be the dimer and trimer polymers.Kutluay et al.  revealedhttps://aidsinfo.nih.gov/drugs/Search/a-z/all), and the development of these agents is a daunting challenge. Because the current treatments for HIV-1 normally include the use of multiple drugs in an attempt to control this virus, we proposed and analyzed four theoretical combined methods for inhibiting Gag transport and assembly based on our model. These analyses might be helpful to the design of new anti-AIDS drug.In the wake of developments in basic science, many of the most promising HIV drugs in clinical development do not target specific retroviral enzymes but rather act by interrupting the assembly of viral factors with host proteins . For exaWe took three approaches, specifically the degradation rates for Gag polymers, Gag-G2A and Gag-dCTD, into account and designed the following four theoretical combined methods:s1 and s2 to the means of the corresponding values for WT Gag and Gag-G2A.C1: Increasing all degradation rates of the polymers by 50% and setting s1, s2 and ki,j to the means of the corresponding values for WT Gag and Gag-dCTD;C2: Increasing all degradation rates of the polymers by 50% and setting s1 and s2 to the means of the corresponding values for WT Gag and Gag-G2A and setting ki,j to the mean of the corresponding values for WT Gag and Gag-dCTD.C3: Setting s1 and s2 to the means of the corresponding values for WT Gag and Gag-G2A, and setting ki,j to the mean of the corresponding values for WT Gag and Gag-dCTD.C4: Increasing all degradation rates of polymers by 50%, setting For these four theoretical combined methods, we computed the concentrations of Gag polymers in the cytoplasm and PM during the first 30 minutes, and the corresponding results are shown in μm3/ymol by increasing the trimer degradation rate to yield the the corresponding concentration of Gag-G2A trimers. The concentrations of Gag polymers are shown in the fourth line in Gag-G2A significantly decreases the concentrations of Gag higher-order polymers and thus might be a potential key drug target. To explore the mechanisms responsible for decreasing the concentrations of higher-order polymers of Gag-G2A, we first reduced the trimer concentration of WT Gag to 0.37 After reducing the trimer concentration in In addition, we compared the tetramer, pentamer and hexamer concentrations obtained with Gag-G2A after reducing the trimer concentration listed in the fourth line in Compared with Gag-G2A, the monomer and dimer concentrations for WT Gag in the cytoplasm are reduced by approximately a quarter and a half, respectively, and the monomer, dimer, tetramer, pentamer and hexamer concentrations for WT Gag on the PM are reduced by approximately 68%, 88%, 93%, 98%, 99% and 99%, respectively. On the PM, Gag-G2A reduces the monomer and dimer concentrations by reducing their active transport speeds, which results in decreases in the concentrations of higher-order polymers on the PM. In the cytoplasm, the low transport speeds of monomers and dimers for Gag-G2A and their very weak diffusions lead to the high monomer and dimer concentrations, and most of these monomers and dimers are gathered near the perinuclear area. However, due to the high degradation rates, these high concentrations near the perinuclear area show rapid reductions. Therefore, in the entire cytoplasm, these monomer and dimer concentrations are ultimately lower than those found for WT Gag.In this study, we developed a model to simulate the intracellular trafficking and polymerization of HIV-1 Gag protein. The model parameters were fitted using published experimental data . The proThere is no denying that the presented modeling approach is merely an approximation to reality. However, it successfully provides a consistent and quantitative description of the transport and polymerization of Gag and lays a broad foundation for further developments. Future experimental and theoretical research is required to support the various assumptions employed in the model.A number of important questions have not been fully addressed and need for further examination. For instance, there are two types of motor proteins: one conveys cargo to the nucleus, and the other conveys cargo to the PM. We consider only the average velocity of the transport of cargo to simplify the model. Thus, it is important to address the transport processes of these two types of motor proteins in future studies. In addition, a dynamical analysis  of HIV-1


The prepared ACs were tested to remove 4-chlorophenol (4-CP) from aqueous solutions by means of batch adsorption process. The prepared 2:1 AC exhibited the highest uptake with a maximum of 525 mg/g. Equilibrium pH studies showed that 4-CP removal was pH dependent; the maximum uptake occurred at an equilibrium pH value of 5.5. Dynamic studies showed that 4-CP uptake on 2:1 AC is rapid, with 80% of the maximum uptake achieved during the first 40 min. Both surface adsorption and intraparticle diffusion were identified to be effective adsorption mechanisms. Kinetic studies indicated a pseudo second-order reaction. Results of equilibrium adsorption experiments showed that the adsorption of the 4-CP on 2:1 AC is best described by the Langmuir model. The thermodynamics parameters of the adsorption  were determined by studying the adsorption equilibrium at different temperatures. The values of these parameters indicated the spontaneous and endothermic nature of the adsorption phenomenon of 4-CP on the prepared ACs.Five different activated carbons (ACs) have been prepared from dried date pits using air and phosphoric acid as activating agents. The used phosphoric acid:date pit ratio dictated the characteristics of the prepared ACs; the equivalent BET-nitrogen surface area varied from 794 m Chlorophenols and other phenol-based compounds have come to represent some of the most dangerous and persistent organic pollutants because of their various industrial applications . Many ofFor obvious reasons, the removal of chlorophenols, and the precursor phenols, from polluted areas and water sources is of utmost importance. Many methods for their removal have been investigated, including biological treatment with microorganisms ,7,8 and etc.). After kneading, the precursor is carbonized and washed to produce the final AC. The chemical incorporated into the interior of the precursor particles reacts with the thermal decomposition products reducing the evolution of volatiles and inhibiting the shrinkage of the particles. This increases the conversion of the precursor to carbon and produces carbons with large internal porosity. After the heat treatment, the chemical is removed by copious washing [Activated carbon has proven to be a very effective adsorbent for many types of inorganic and organic compounds because of its high surface area and unique chemical properties, including the polarity and nature of surface functional groups. The surface chemistry of these carbons and the chemical characteristics of adsorbate, such as polarity, ionic nature, functional groups, and solubility, determine the nature of the adsorption mechanism, as well as the extent and strength of adsorption. Moreover, the porous structure of activated carbon consists of a network of interconnected macropores, mesopores, and micropores that provide a good capacity for the adsorption of organic molecules. Thus, it is expected that various mechanisms and forces, such as ion exchange, covalent bonding, van der Waals forces, H-binding, dipole-dipole interactions, and cation- and water-bridging, can be responsible for adsorption of organic compounds in activated carbon ,22,23,24 washing . In the  washing . A possi washing . The cry washing .Moreno-Castilla  investigPalm dates grow abundantly in tropical regions and the gulf countries of the Middle East; after processing the fruits, the residual stones, which constitute approximately 10% of the weight of the dried fruit , represeIn our previous study, we used the activated carbon prepared from date pits to remove phenol from aqueous solution. The study involved dynamics and equilibrium analysis only. For this study, raw date pits were carbonized and activated by air and phosphoric acid; the resulting activated carbon was evaluated for its 4-CP sorbent capacity. The effects of solution pH on adsorbent capacity were investigated and the Langmuir and Freundlich models were utilized to describe the adsorption behavior. Parameters for each of these models were determined by non-linear error estimation using the derivative of Marquarrdt’s Percent Standard Deviation (MPSD). The pseudo second-order kinetics and Elovich equation, in addition to the Weber and Morris equation, and diffusion models were used to analyze the dynamics of sorption of the 4-CP on the prepared AC. Thermodynamics analysis of the 4-CP adsorption was carried out using both the Arrhenius and van’t Hoff equations.Five different activated carbons were prepared from date pits according to a method discussed in our previous work . The appeqH+/g) of functional groups available on the 2:1 AC.Samples of the prepared ACs were tested using a Micrometrics ASAP 2010   gas adsorption surface area and porosimetry analyzer. In this test, nitrogen adsorption isotherms at 77 K were obtained, as shown in et al. [2 on pH. The point of zero charge (pHpzc) was defined as the point where the pH final vs. pH initial curve crosses the line pHinitial = pHfinal.The point of zero charge was determined using the acid–base titration method developed by Newcombe et al. . SeveralBatch adsorption experiments were conducted by adding the appropriate amount of the prepared ACs into 100 mL reagent bottles containing 50 mL portions of 4-CP solution. Different initial concentrations of the 4-CP (10–400 ppm) were used in the equilibrium studies. The experimental procedures for measuring adsorption kinetics, equilibrium, and thermodynamics are described and discussed in detail in our previous studies . The coni.e., uptake) was calculated using Equation (1):eq is the equilibrium uptake (mg/g); oC is the initial 4-CP concentration (mg/L); eC is the equilibrium 4-CP concentration (mg/L); V is the volume of the solution (L); and w is the mass of the adsorbent (g).The adsorption capacity  of the 2:1 AC was found to be 7.2 following the procedure outlined earlier in the materials and methods section. Adsorption of 4-CP on 2:1 AC was studied over the range of pH 5.5–10.5, and the results are shown in According to Moreno-Castilla , the soli.e., 5.5, and at different temperatures. The results of the change of 4-CP uptake with time are presented in Dynamics of the adsorption of 4-CP on the prepared ACs was investigated with 100 ppm 4-CP solution on 2:1 AC at the optimum pH; It is evident from this figure that the uptake of 4-CP on 2:1 AC is rapid; more than 85% of the maximum uptake occurs during the first 40 min. After 40 min the adsorption process plateaus and becomes slower, near equilibrium. In between these two stages of uptake, the rate of adsorption is found to be nearly constant. This can be explained based on the fact that during the first 40 min, a large number of vacant surface sites are available for adsorption; thus, the uptake increases rapidly. After 40 min, the remaining vacant surface sites are sterically and electrostatically hindered due to the repulsive forces between the solute molecules on the solid and bulk phases; thus, the uptake advances more slowly.eq (mg/g) is the uptake at equilibrium; tq (mg/g) is the uptake at time t (min); 2k (g/mg·min) is the equilibrium rate constant of pseudo second-order sorption kinetics. Equation (2) can be solved with the boundary condition: The adsorption of 4-CP on 2:1 AC can be analyzed by the pseudo second-order kinetics given by :(2)dqtdeq and k2, can be determined by either fitting the equilibrium data to linear-equivalent forms or using nonlinear regression techniques. In this study, the Composite Fractional Error Function (CFEF) [eq, respectively. Using CFEF, the parameters of the pseudo second-order rate k2 and eq, at different temperatures are listed in The adjusted n (CFEF) , defineda and b are the constants determined during an experiment. The constant, a, is regarded as the initial rate because dqtdoaches 0 . EquatioThe intercept of Equation (6) indicates the amount of adsorption in a short time, as articles .a and b, were found and listed in Using Equation (4), the parameters of the Elovich equation, idk (mg/g·min1/2) is the intraparticle diffusion rate constant and C (mg/g) is a constant that is related to the thickness of the boundary layer, i.e., the larger the value of C the greater is the boundary layer effect. To investigate the diffusion mechanism of the 4-CP adsorption onto the carbon, the intraparticle diffusion model described by Equation (7), proposed by Weber and Morris , was utiAdsorption isotherms describe the relationship between the amount adsorbed by a unit mass of solid sorbent and the concentration of dissolved adsorbate in the liquid at equilibrium. monq and LK are the Langmuir constants, which are related to the amount of adsorption corresponding to monolayer coverage, or adsorption capacity, and the energy of adsorption, respectively.The Langmuir and Freundlich models are the most common adsorption isotherm models that are used to describe the adsorption equilibrium data. The Langmuir isotherm assumes that: (1) sorption occurs uniformly on the active sites of the sorbent, and (2) once a sorbate occupies a site, no further sorption can take place at this site. Based on these assumptions, the Langmuir isotherm model in its simple form is given by Equation (8):K and n are the Freundlich constants and are indicators of adsorption capacity and adsorption intensity, respectively.While the Langmuir isotherm model assumes uniform adsorption energies and homogeneous monolayer, the Freundlich isotherm model is given by Equation (9):The adjustable parameters of both the Langmuir and Freundlich models were determined for the adsorption of the 4-CP on the 2:1 AC at different temperatures, as shown in The parameters, along with the values of MPSD, are listed in monq, of 4-CP on different adorbents. As it can be noticed, the 2:1 AC is considered among the highest Langmuir monolayer adsorption capacities.H0, standard entropy ∆S0, and standard free energy ∆G0 due to the transfer of a unit mole of solute from solution onto the solid–liquid interface, as well as the activation energy of adsorption, aE [Thermodynamics analysis in sorption studies usually involves studying sorption equilibrium and kinetics at different temperatures. The temperature dependency of the 4-CP adsorption onto the prepared ACs was investigated by studying the effect of temperature on the adsorption equilibrium and kinetics of the adsorption process, as shown in tion, Ea .H0 and ∆S0, while ∆G0 can be calculated using the equation:The van’t Hoff equation:K2 is the equilibrium rate constant of pseudo second-order sorption kinetics, k0 is the Arrhenius factor, and aE is the Arrhenius activation energy of adsorption. The activation energy of the adsorption can be determined using the linearization form of Arrhenius equation, given by:G0 confirms the feasibility of the adsorption of 4-CP on the prepared ACs and the spontaneous nature of the adsorption process. Positive value of ∆S0 reflects the affinity of the prepared ACs for the 4-CP and the increasing randomness at the solid–solution interface with some structural changes in the adsorbates and adsorbents during the adsorption process. Positive values of ∆H0 indicate that the adsorption of 4-CP on the prepared AC is endothermic, which agrees with the experimental data where adsorption increases with increasing temperature as shown in The negative values of ∆The activated carbons produced from date pits have proven to be efficient adsorbent for the investigated toxin pollutant, namely 4-Chlorophenol. The adsorption process on the prepared activated carbons was found to be pH dependent; it decreased by increasing pH. Dynamics studies on the prepared activated carbons revealed that Elovich equation appropriately could describe the kinetics of adsorption for the prepared ACs and the process followed pseudo second-order kinetics with the involvement of film, pore, and surface diffusions, as well as adsorption on the pore surface. Equilibrium studies indicated that Langmuir isotherm model best described the adsorption of 4-CP on the prepared activated carbon. The determined thermodynamic properties, indicated the spontaneous and endothermic nature of the adsorption process of 4-CP on the prepared ACs.


The aim of this study was to construct an electronic bowel sound recording system and determine its usefulness for the diagnosis of appendicitis, mechanical ileus and diffuse peritonitis.A group of 67 subjects aged 17 to 88 years including 15 controls was examined. Bowel sounds were recorded using an electret microphone placed on the right side of the hypogastrium and connected to a laptop computer. The method of adjustable grids (converted into binary matrices) was used for bowel sounds analysis.Significantly, fewer (p ≤ 0.05) sounds were found in the mechanical ileus (1004.4) and diffuse peritonitis (466.3) groups than in the controls (2179.3). After superimposing adjustable binary matrices on combined sounds , significant relationships (p ≤ 0.05) were found between particular positions in the matrices (row-column) and the patient groups. These included the A1_T1 and A1_T2 positions and mechanical ileus as well as the A1_T2 and A1_T4 positions and appendicitis. For diffuse peritonitis, significant positions were A5_T4 and A1_T4.Differences were noted in the number of sounds and binary matrices in the groups of patients with acute abdominal diseases. Certain features of bowel sounds characteristic of individual abdominal diseases were indicated.BS: bowel sound; APP: appendicitis; IL: mechanical ileus; PE: diffuse peritonitis; CG: control group; NSI: number of sound impulses; NCI: number of combined sound impulses; MBS: mean bit-similarity; TMIN: minimum time between impulses; TMAX: maximum time between impulses; TMEAN: mean time between impulses.Zaborski D, Halczak M, Grzesiak W, Modrzejewski A. Recording and Analysis of Bowel Sounds. Euroasian J Hepato-Gastroenterol 2015;5(2):67-73. It is one of the elements that enable food digestion and absorption of its products. In the small intestine, segmental and peristaltic contractions can be distinguished.2 disease entities and operative procedures. The peristalsis of the digestive tract is accompanied by sounds5 whose source is the passing mixture of chyme and gas.6 Clinical examination includes the auscultation of peristaltic sounds using a stethoscope.7 The character of bowel sounds (BS) altered in acute abdominal diseases and after operative procedures is an important diagnostic indicator. A significant increase in BS intensity takes place in the onset of mechanical ileus, food poisoning with diarrhea and gastrointestinal hemorrhage. The complete absence of these sounds indicates complete paralytic ileus and occurs mainly in the diffuse peritonitis, appendicular perforation, peptic ulcer perforation, in the final phase of mechanical ileus and in intraperitoneal bleeding. Operative procedures, in which the peritoneal cavity is opened, result in the temporary intestinal paralysis and, consequently, the absence of BS.10Intestinal motility depends on many factors, such as the amount and type of ingested food, emotional state, drugs,Bowel sounds auscultation, commonly applied in clinical practice, is based on subjective assessment using the stethoscope. The most frequently described parameters are sound frequency and loudness. It can be assumed that BS provides much more information on disease or health, which could be used in diagnostics.Therefore, the aim of the present study was: (1) to construct a device for BS recording, (2) to develop the methods for saving and storing data, (3) to determine the characteristic features of BS from healthy subjects and patients and their usefulness in the diagnosis of acute abdominal diseases.Bowel sounds were recorded using a standard electret microphone (placed in a Teflon profiled sleeve), a two-stage voltage amplifier and a laptop computer equipped with a 16-bit Sound Blaster card. Headphones with an amplifier were also used to control recording process. Four-minute recordings were saved to the computer hard disk as wave files with a sampling frequency of 16 kHz.Bowel sounds were auscultated after obtaining patient’s informed consent. The study was approved by the local ethics committee. The patient was laid supine and the microphone was placed on the abdomen skin, 2 to 3 cm to the right of the umbilicus. In the case of excessive hair, the microphone was moved in the lateral direction. During the examination, the patient was requested to remain silent, avoid making any movements and breathe calmly. The sounds were recorded in a quiet isolated room. The quality of the recorded signal was being controlled in real time using the headphone system. The examinations were performed in 67 subjects after an overnight fasting hospitalized in the third clinic of general and vascular surgery. Seven persons were excluded from further analysis due to the low quality of recordings.Patients’ age ranged between 17 and 88 years (mean 48.3 years). Women were in majority (63%). Forty-five subjects with acute abdominal diseases were examined. Control group (CG) included patients hospitalized in the clinic due to other diseases. Bowel sounds in the subjects with the symptoms of acute abdomen were recorded after preliminary diagnosis and before surgical procedure. Four groups of patients were distinguished.The group of 27 patients with appendicitis (APP) included 18 women, 17 to 74 years of age (mean age of 32.9 years) and 9 men, 17 to 71 years of age (mean age of 37.1 year). In two cases, appendicitis was accompanied by the ovarian cyst rupture, in one case by Meckel’s diverticulitis and also in one case by the sigmoid perforation. Among 14 patients with mechanical ileus (IL), there were eight women aged 42 to 88 years (mean age of 68 years) and six men aged 56 to 76 years (mean age of 66.5 years). Most frequently (in six cases), mechanical ileus was caused by peritoneal adhesions, followed by incarcerated hernia (four patients), neoplastic disease (two patients), intussusception (one patient) and sigmoid volvulus (one patient). In the group of four patients with diffuse peritonitis (PE), there was one 84-year-old woman and three men 40 to 53 years of age (mean age of 48.3 years). In all cases, the diffuse peritonitis was caused by the gastric ulcer perforation. The control group (CG) consisted of 15 persons, including 11 women and four men. The women’s age ranged from 24 to 77 years (mean age of 49.3 years), whereas men’s age ranged between 35 and 73 years (mean age of 59.5 years). Conditions other than acute abdominal diseases were the reason for hospitalization in these cases.13 was utilized for the computer analysis of recordings. It was originally developed for speech recognition and consisted of superimposing two-dimensional grids on sound impulses, whose location and width were determined based on signal local minima. The grid width was automatically adjusted to sound duration and the grid height to its amplitude. Next, the grid cells crossed by the signal were filled with ones and the cells without signal with zeros. Thus, the binary matrix was obtained, which can be further analyzed by comparing it with standard matrices stored in a database in order to identify disease entities  determining the reference level for local minima by averaging the values of the first 100 signal samples, (2) reading consecutive samples and saving the start and stop times of sound impulses, (3) determining the number of sound impulses in the recording, (4) combining adjacent sound impulses , (5) superimposing adjustable grids of 35 cells (5 × 7) on combined impulses, (6) calculating a binary matrix for each combined impulse, (7) finding similar matrices in a database, (8) calculating mean bit-similarity between matrices, (9) determining the minimum, maximum and the mean time intervals between the impulses. The recordings of 60 subjects from all groups were analyzed using this algorithm. The following continuous variables were obtained directly from this analysis: number of sound impulses (NSI), number of combined sound impulses (NCI), mean bit-similarity (MBS) expressed as a percentage, minimum (TMIN), maximum (TMAX) and mean (TMEAN) time between impulses expressed in seconds.In order to explicitly characterize the position within a matrix, its coordinates, e.g. A1_T1, were determined . Three mNext, the matrices for patients within groups were compared to determine the number of matched bits (pairs 1-1 and 0-0) at the same positions in both matrices and the number of differing bits (pairs 1-0 and 0-1). The variables shown in 14 The differences were considered statistically significant at p ≤ 0.05.The results were subjected to statistical analysis. The normal distribution of continuous variables was verified with the Shapiro-Wilk test. Non-parametric tests  were used for comparisons due to the lack of normal distribution and variance homogeneity as well as low sample sizes. The analysis of categorical variables (zero or one in the matrix and disease entity) was based on contingency tables using the Chi-square and Fisher’s exact tests.The analysis of variables describing BS revealed that the number of sound impulses was significantly lower in the IL and PE patients compared with the CG. For the remaining variables, no statistically significant differences were found .The correlation analysis of these variables showed a statistically significant negative relationship between the number of impulses and the maximum time interval between impulses in the IL group  and the APP group .In the analysis of variables describing binary matrices, a significantly lower percentage of bits equal to one in the a1 row were found in the PE patients compared with the IL patients and the CG . On the In the analysis of variables describing bit-similarity, a significantly higher number of differing pairs (0-1 or 1-0) was found in the IL group compared with the PE group . Also, sThe last stage of the present work was the verification of relationships between the presence of 1 or 0 at a given position in the matrix and the patient’s group . The A1_T1 and A1_T2 positions were associated with IL, whereas the A1_T2 and A1_T4 positions were related to APP. For PE, significant positions in the binary matrices included A5_T4 and A1_T4.15 However, it lacks objectivity and makes it impossible to compare the results of different examinations. The first attempt at making it more objective was made by Cannon16 in 1905, who presented his own BS graphically. In the present study, the electronic system was used. As shown by Craine et al,17 the use of an electronic stethoscope and digital analysis allows for the detection of approximately 5 times more sounds than during the standard examination. Besides, this method enables an objective and quantitative evaluation of BS.1522The auscultation of the abdomen has been applied in clinical practice for centuries. It is a simple, non-invasive and safe method.23 Various solutions have been proposed to eliminate such artefacts.172224 In the present study, the shape of the sleeve used with the microphone ensured good adhesion to the abdominal wall and the possibility of recording the signal from an area of 12.5 cm2. The next source of potential noise is the surroundings where the examination is performed. The best method for eliminating such unnecessary sounds is recording in a soundproof chamber.2122One of the basic problems with BS recording is the occurrence of noise, which partially results from the friction between the microphone and the skin during the patient’s respiratory movements.1726 Various algorithms based on wavelets and filters were proved to be successful in this respect.252728 According to Yoshino et al22 noise can also be generated by the sounds accompanying the heart-beat and respiratory function. The preliminary analysis of the sound files in the present study showed that when the microphone was located on the right side of the hypogastrium, these impulses were so weak that they did not exceed the background level. Therefore, they were not analyzed by the program used in the present work. A similar opinion was presented by Craine et al.17Regardless of the application of the above-mentioned methods, the denoising stage is crucial to an appropriate BS analysis.22 Craine et al17 examining patients with the irritable colon syndrome recorded BS for 2 minutes, whereas Kelemen29 considered it essential to auscultate BS for at least 5 minutes.The time of BS recording was empirically set at 4 minutes. This choice was mainly dictated by the necessity of performing quick diagnosis in a patient requiring surgical intervention. At the same time, sound duration is sufficient to carry out further analysis. Yoshino, like Sugrue and Dalle, used 10 to 15-minute recordings, however, they did not explain their choice.23 BS are characterized by low energy observed on the surface of the integuments and by large dynamics, i.e. periodic occurrence of loud sounds. The calibration of the system for sounds of high energy may lead to the loss of quiet impulses. On the other hand, an opposite situation causes the saturation effect, when the impulse of high energy appears. This may lead to the errors in the frequency analysis. Although in the present work this phenomenon occurred in some recordings, the saturation effects were relatively small compared with the signal amplitude and they did not significantly bias the results.The problem of the saturation effect present in the BS recordings remained unsolved in the present study. According to Horn and Mynors,24 who calculated selected signal parameters  and developed classification rules based on these parameters.The application of adjustable grid method to the BS analysis was motivated by its two main features: (1) it is easy to use and enables rapid examination, and (2) it gives objective and repeatable results that can be verified statistically. Therefore, an attempt was made at identifying sounds associated with acute abdominal diseases. An alternative way of BS classification was proposed by Li et al27 the median duration of silence periods between sounds was excluded from further analysis due to the lack of correlation with any of the first four principal components. On the other hand, Sugrue et al21 found significant differences in sound intervals between the control group and the patients suffering from appendicitis, acute cholecystitis and obstruction.In the present work, the number of sound impulses was lower in the IL and PE patients compared with the CG . It shouThe analysis of variables shown in The analysis of bit-pairs showed that the highest similarity existed for the 0-0 pairs in the PE patients. This proves the repeatability of zero bits at corresponding positions in the matrices for individual patients of this group. These results were also significantly different from those in the CG . The smaThe analysis of relationships between the presence of one or zero at a given position in the matrix and the membership in a given group made it possible to indicate the key positions in the matrices, where the presence of bits was highly correlated. Matrix positions, where the value of bits  was not accidental and depended on the type of disease were determined. In the present work, the relationship existed only at four positions in the matrix with 35 cells. This result did not allow us to develop standard matrices that could be used for disease identification. The application of the method presented in this study in clinical diagnostics requires its further improvement. However, the stages of BS recording and storing were fully developed. The recordings were of high quality and could have been further analyzed.In summary, the method employed in this study makes it possible to determine the number of sound impulses and silence duration. The results are in accordance with those presented by other authors. The indicated key positions in the matrices, where the statistically significant relationships existed, allow us to conclude that it would be possible to design standard matrices and determine the sounds that are characteristic of a given disease entity. The isolation of pathognomonic sounds would, in turn, allow for the development of a simple diagnostic method based on the auscultation of the abdomen.