Six varieties each of indica and japonica rice were grown in hydroponics and the chemical properties of the root surface were analyzed, including surface charges and functional groups (-COO- groups) as measured by the streaming potential and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). Binding forms of heavy metals adsorbed on rice roots were identified using sequential extraction methods. In rice roots exposed to Cu and Cd solutions, Cu existed mainly in both exchangeable and complexed forms, whereas Cd existed mainly in the exchangeable form. The amounts of exchangeable Cu and Cd and total adsorbed metal cations on the roots of indica varieties were significantly greater than those on the roots of japonica varieties, and the higher negative charges and the larger number of functional groups on the roots of indica varieties were responsible for their higher adsorption capacity and greater binding strength for Cu and Cd. Surface charge and functional groups on roots play an important role in the adsorption of Cu and Cd on the rice roots.This work was designed to understand the mechanisms of adsorption of copper (Cu) and cadmium (Cd) on roots of  Rice is one of the most important crops in the world and the staple of choice in China: the average daily rice consumption per capita (219 g) in China is almost 50% more than the global average (148 g) . Rice nejaponica and indica  accumulation in indica and japonica rice in China. When Cu concentrations in polished grains of 285 rice cultivars were measured, the average concentration in indica rice was found to be double of that in japonica rice , an aluminum-tolerant variety, was less negative than that of Yangdao-6 (indica). However, such differences in intact roots and their effects on the adsorption of heavy metals by the roots are yet to be studied.The root surface is the first barrier that anions and cations need to cross in order to enter the plant, especially in non-hyper accumulating species. Therefore, examining the adsorption of anions and cations on roots is the first step to a better understanding of the relationship between the concentrations of the anions and cations in soil solution and their contents within plants. Sorption of metals by roots is due to the binding and electrostatic attraction by a limited number of cation exchange and binding sites on the surface of the cells, which impart a negative charge to the root surfaces. The type and number of these sites vary with species because of the composition of root cells and cell wall constituents that carry the functional groups. indica and japonica are universal; (2) to examine the effects of these differences on the adsorption of Cu and Cd on rice roots; and (3) to find out the possible mechanisms of such adsorption.Recently, a streaming potential intrument has been developed to measure the zeta potential of intact roots and was used for investigating the relationship between the zeta potential of rice roots and the adsorption of aluminium (Al) by those roots . In the Oryza sativa L.) commonly grown in China were used, six each of japonica  and indica . The rice seeds were surface-sterilized with 30% H2O2 for 15 min, washed thoroughly with deionized water, soaked in deionized water for 4 h, and germinated at 25°C in darkness on a piece of gauze placed inside a polythene container. When the seedlings had grown about 2 cm tall, they were moved to a growth chamber with day/night temperatures of 27/20°C, a day length of 14 h, a light intensity of 375 μmol photon m-2 s-1, and a relative humidity of 70% and grown in a modified nutrient solution recommended by the International Rice Research Institute without being aerated (4)2SO4, 1.5 NaNO3, 0.32 NaH2PO4⋅2H2O, 0.5 K2SO4, 1.7 MgSO47H2O, and 1.0 CaCl2, supplemented with  9.1 MnCl2⋅4H2O, 0.16 CuSO4⋅5H2O, 0.15 ZnSO4⋅7H2O, 0.07 (NH4)6Mo7O24⋅4H2O, 18 H3BO3, and 40 FeSO4⋅7H2O-EDTA. The nutrient solution (pH 5.5) was renewed every 3 days. After 15 days, uniform-looking seedlings were selected and transplanted into PVC pots . The plants were carefully removed after 25 days and their roots, washed in deionized water, were used for the subsequent experiments.Twelve cultivars of rice , and 0.01 M HCl, 1 h in each solution, to extract the exchangeable, complexed, and precipitated Cu or Cd from the root surfaces, respectively  and Cd(II) were reduced to Cu(I) and Cd(I) by root exudates during the adsorption experiments. However, the amount of Cu(II) and Cd(II) reduced should be low due to weak reducing condition and short reaction time of 2 h.The zeta potential of rice roots was measured using the streaming potential equipment developed by our group . The roo0 is the permittivity of free space (F/m), and κ is the conductivity of the solution (S/m).where ΔE is the streaming potential (mV); ΔP is the difference between the liquid pressures (Pa); μ is the dynamic viscosity of the solution (Pa S); ε is the permittivity of the test solution (F/m); ε-1 with a resolution of 4 cm-1 and 64 scans.The ATR-FTIR spectra of rice roots exposed to 100 μM Cu or 100 μM Cd were measured using a Nicolet iS10 FTIR spectrometer  equipped with an ATR diamond crystal . The spectral range was 650–4000 cmjaponica and six indica, and their average zeta potentials were calculated and the results were expressed as means ± standard deviation. Data processing and statistical analyses were carried out using SPSS ver. 20.0 for Windows . One-way analysis of variance (ANOVA) was used in all experiments to ascertain whether the differences between treatments were significant at P < 0.05 (Pearson’s correlation).The average values of Cu and Cd adsorbed by the roots of each of the 12 cultivars, six Figure 1). The exchangeable form of both metal cations accounted for the largest share, followed, in that order, by the complexed and the precipitated forms, the share of exchangeable Cd being greater than that of Cu. For example, when the concentration of metals was 100 μM, exchangeable Cu on the root surface accounted for 50.9% of the total Cu in indica and 48.7% in japonica, whereas the corresponding values for exchangeable Cd were 69.1 and 71.2%. However, complexed Cu accounted for a greater proportion in the total than complexed Cd did. At the initial concentration of 100 μM, complexed Cu contributed 37.0% of the total in indica and 38.7% in japonica, the corresponding figures for Cd being 15.2 and 15.6%. Exchangeable Cu and Cd on the roots of indica were significantly higher than those on the roots of japonica (P < 0.05) . The complexed forms of Cu and Cd were also higher in indica but the differences between the two types of rice were not significant except for complexed Cu at 100 μM . The differences between the two types of rice with respect to the precipitated forms of Cu and Cd were not significant.After the roots had been exposed to Cu or Cd, the metal cations on the roots could be differentiated into their respective exchangeable, complexed, and precipitated forms : the difference was significant (P < 0.05), suggesting that root surfaces of indica rice carry a greater negative charge and thus have greater electrostatic attraction for metal cations.The zeta potential of roots of 40-day-old plants of different rice varieties is shown in indica and japonica varieties are shown in Figure 3. The absorption bands at 1635, 1543, and 1247 cm-1 were attributed to amide I (antisymmetric stretching vibrations of carboxyl), amide II (N–H bending vibrations), and amide III (C–N stretching and N–H bending vibrations) . These results indicate that although both indica and japonica have the same surface functional groups on their roots, the groups are present in larger numbers on the roots of indica, which explains the greater negative charge on its roots.The functional groups on rice roots are the major sources of the negative charge and binding sites for heavy metal cations. The ATR-FTIR spectra for the roots of rations) . The pearetching ; the peaellulose ; and theellulose . The peaectively . No obvijaponica group tolerate Al toxicity better than those of the indica group do . When the roots were exposed to Cu or Cd, the exchangeable forms of adsorbed Cu and Cd on the roots of indica were significantly greater than those on the roots of japonica . The exchangeable forms of Cu and Cd were adsorbed on the negatively charged roots through electrostatic attraction between the heavy metal cations and the root surface. The greater negative charge on the roots of indica varieties adsorbed greater exchangeable Cu and Cd. The cations of Cu and Cd adsorbed electrostatically on rice roots were located in the diffuse layers of the electric double layers on the negatively charged surfaces of the roots. These cations are highly reactive and easily absorbed by plants. Therefore, the greater electrostatic adsorption of Cu and Cd on the roots of indica rice caused by the greater negative charge on the roots may be one of reasons for the higher uptake and accumulation of Cu and Cd by the indica group. indica) were higher than that of Wuyunjing7 (japonica). indica than in japonica when the rice was exposed to the 10 μM Cu.Rice varieties of the group do . The vargroup do , which igroup do . In the Figure 1). On the other hand, Cu existed mainly in exchangeable and complexed forms; the proportion of precipitated Cu was much lower . Therefore, the surface charge on rice roots plays an important role in the adsorption of both heavy metal cations, especially that of Cd.Of its three binding forms, Cd existed mainly as the exchangeable form on rice roots; the proportions of the complexed and the precipitated forms of Cd were much lower , which confirmed that surface charge was one of important factors determining the adsorption of Cu and Cd on the roots of different cultivars of rice. Compared with the japonica varieties, the indica varieties carried greater negative charge on their root surfaces, which may be one of the reasons why the indica varieties were more sensitive to Cu and Cd and adsorbed more Cu and Cd on their root surfaces than japonica varieties.Correlation analysis was performed between the zeta potential of the roots of each of the twelve rice cultivars tested in this study and amount of Cu and Cd adsorbed on the roots of these rice cultivars. Based on Pearson’s correlation analysis, there was a significant correlation between zeta potential of different rice roots at pH5.5 and amount of Cu and Cd adsorbed on the roots of these rice cultivars  on the cell walls and cell membranes of roots , suggesting that the functional groups were present in larger numbers on the roots of indica and were responsible for the greater negative charge and greater exchangeable Cu and Cd on its roots.The functional groups on rice roots are major sources of the negative charge and of the binding sites for heavy metal cations. Plant roots are negatively charged owing to the deprotonation and protonation of the surface functional groups . So were the directions of the shifts for the two types of stretching: the peak for the antisymmetric stretching vibration shifted to higher wave numbers as rice roots were saturated with Cu or Cd, whereas the peak for the symmetric stretching vibration shifted to lower wave numbers.Wave number separation between the absorption peaks of antisymmetric and symmetric stretching vibrations has been used for determining the binding strength of carboxyl-containing organometallic complexes . The speFigure 5 (Cu) and Figure 6 (Cd), and the results are shown in Figure 8. The data of the separations between the peaks of antisymmetric and symmetric stretching vibrations of carboxyl for six individual indica or japonica varieties were presented in Supplementary Table indica between the peaks of antisymmetric and symmetric stretching vibrations was significantly greater than that of japonica (P < 0.05), suggesting that the strength of binding of Cu and Cd on roots of indica rice was greater than that of japonica rice. Therefore, the preference for Cu and Cd of the roots of indica was stronger than that of the roots of japonica. The results in Figure 8 also indicate that the wave number separation of roots that had adsorbed Cu was greater than that of the roots that had adsorbed Cd, consistent with the greater amount of complexed Cu on rice roots than that of complexed Cd .The average wave number separation between the peaks of antisymmetric and symmetric stretching vibrations of carboxyl was calculated from the spectra in Figure 3 that the roots of the two types differ in their surface chemical characteristics. Wave number separation between the absorption peaks of antisymmetric and symmetric stretching vibrations has been used for determining the binding strength of carboxyl-containing organometallic complexes . This is to be expected, because indica varieties also carried a greater negative charge  and more adsorption sites for heavy metal cations  on their roots. It is evident from the results shown in omplexes . Such a omplexes . Based oFigure 1). Soil organic matter and crop straw biochars behave similarly . The binding strength of the roots of indica varieties for Cu and Cd was greater than that of the roots of japonica varieties. When rice roots were exposed to Cu and Cd solutions under acidic conditions, Cu existed mainly in exchangeable and complexed forms on the roots, whereas Cd existed mainly in the exchangeable form. Therefore, the surface charge and the number of functional groups on rice roots play an important role in the adsorption of Cu and Cd by roots. The greater electrostatic adsorption of Cu and Cd by the roots of indica due to the greater negative charge on the roots may be one reason for the greater uptake and accumulation of Cu and Cd by indica rice as compared to japonica rice. These findings are of fundamental significance in understanding the mechanisms of the uptake and accumulation of Cu and Cd by indica and japonica varieties of rice and, consequently, the environmental risks posed by the accumulation of these heavy metals in the grains of the two types of rice.Roots of Z-DL and R-KX designed the experiments. Z-DL and QZ performed the experiments. Z-DL drafted the manuscript. R-KX and Z-NH revised the manuscript.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.


Furthermore, the ionospheric monitoring results of site JFNG in the northern hemisphere, and CUT0 in the southern hemisphere during the period from 1 January to 31 December 2015 are presented and discussed briefly.The current constellation of the BeiDou Navigation Satellite System (BDS) consists of five geostationary earth orbit (GEO) satellites, five inclined geosynchronous satellite orbit (IGSO) satellites, and four medium earth orbit (MEO) satellites. The advantage of using GEO satellites to monitor the ionosphereis the almost motionless ionospheric pierce point (IPP), which is analyzed in comparison with the MEO and IGSO satellites. The results from the analysis of the observations using eight tracking sites indicate that the ionospheric total electron content (TEC) sequence derived from each GEO satellite at their respective fixed IPPs is always continuous. The precision of calculated vertical TEC (VTEC) using BDS B1/B2, B1/B3, and B2/B3 dual-frequency combinationsis compared and analyzed. The VTEC The second-generation BeiDou Navigation Satellite System (BDS), on 27 December 2012, became the third system around the world, after the Global Positioning System (GPS) and Global Navigation Satellite System (GLONASS), to provide position–navigation–time services ,4. It isOver the past two decades, the total electron content (TEC) of the ionosphere from GPS dual-frequency measurements have widely been used to study variations in the ionosphere, including its long-term characteristics, day-to-day fluctuation, and storm effects ,10,11,12k and m indicate different frequency. P denotes the code measurements (m). I is the ionospheric delay along the satellite signal propagation path, which can be written as a function of the slant TEC (STEC)  [f is the frequency of the BDS signal in Hz. c is the speed of light. ε is the combination of the measurement noise and the multipath in the meter.For ionospheric study, the TEC is computed using dual-frequency geometry free (GF) linear combination ,6,9,12:(The STEC can be easily expressed as a function of TEC from Equations (1) and (2):Because of the satellite signals pass the whole ionosphere (60~1000 km), users usually assumed that all electrons in the ionosphere were concentrated in a thin layer around the earth at an altitude about 350 km. The intersection point between the line of the satellite to the receiver and the layer is called the ionospheric pierce point (IPP). eR is the mean radius of the Earth. H is the height of the single layer above the earth’s surface. z is the zenith distances at site. H = 350 km and α = 0.9782 are the recommended values of Bernese software [In order to easily study the various behaviors of ionosphere, the STEC can be converted into vertical TEC (VTEC) at IPP using the modified single-layer model (MSLM) mapping function ,14:(4)VTAs carrier phase measurements are much less affected by measurement noise and multipath than code measurements, but its ambiguity algorithm is more difficult, the carrier phase ionosphere observations are used to smooth the code ionospheric observations.There have been a few studies on ionospheric monitoring using GEO satellites. Wu et al. (2013) investigated ionospheric TEC monitoring using BDS GEO measurements at the initial stage of BDS operation in China, and preliminarily analyzed the precision . KunitsyRecently, with the continuous development of BDS, there are now more than 120 International GNSS Service (IGS) sites around the world that can receive BDS signals . More anIn order to compute the result, we selected eight sites from the IGS tracking network. The longitude of most of the sites is between 100° E and 126° E; the KZN2 and KRGG sites are not within this range because there are no ideal sites at about 55° N and 55° S that can be used to track BDS GEO satellites. In order to more clearly describe the advantage of BDS GEO satellites in ionospheric monitoring, we will compare and analyze the different characteristics in satellite visibility, satellite elevation, and variation in the IPP for the GEO, IGSO, and MEO satellites. The GEO satellites are almost stationary compared to the large amplitude motions of the IGSO and MEO satellites, and motions of the corresponding IPPs are also negligible. The position of the IPP can be calculated by making use of the geometric relationship between the sites and satellites. Based on the above analysis, the IPP of the GEO satellite compared to the MEO and IGSO satellite is almost motionless, and the high-precision TEC at the fixed IPP can be calculated continuously; the TEC sequence only changes over time and can be directly used for the study of time-dependent characteristics of the ionosphere. However, for MEO and IGSO satellites, the ionospheric TEC simultaneously varies with time and space, thus, it is impossible to calculate a continuous sequence of TEC at a fixed point directly. To study the variation characteristics of ionospheric TEC, we must adopt a method of modeling or interpolation, which can introduce a model error; and there might be an especially large error when an ionospheric anomaly is present.k and m in units of meter.The STEC can be obtained from the dual-frequency GF combination using Equation (3), and the STEC can be converted into the VTEC using Equation (4). The error of the projection function is small and can be neglected when the satellite elevation is greater than 30° . Followiproducts . σPk−Pm=12, VTEC13, and VTEC23, respectively. The corresponding coefficient is For BDS triple-frequency  measurements, three different dual-frequency GF combinations can be formed, and the VTEC calculation using the three combinations are denoted as VTECThe maximum PMN is typically a quarter of the wavelength , which i12 based on carrier phase observations will be less than 0.69 TECU, which is more accurate than that of the code. However, it is very difficult to handle the carrier phase ambiguity parameters, so the follow-up analysis is based on the code and smoothed code observations.The carrier phase wavelength of B1, B2, and B3 is 19.20 cm, 24.83 cm, and 23.63 cm, respectively, and the maximum PMN is 4.8 cm, 6.2 cm, and 5.9 cm, respectively. In fact, we can use the triple-frequency ionosphere-free and geometry-free combinations of the carrier phase measurements to calculate the combined PMN of the three frequencies ,22,23,2423 has the lowest precision because the combination coefficient It can be clearly seen that TEC12 and VTEC13 for sites JFNG and SIN1 on Day 029/2015. We can see that the trend of VTEC based on the code and smoothed code is consistent, and the values are close. There is little difference between VTEC12 and VTEC13. The calculation results of eight sites in 12 has the highest precision, so only the combination B1/B2 will be used in follow-up analysis.12 derived from the smoothed code and IGS GIM interpolation at the same IPP at site CUT0, JFNG, and SIN1 from 1 January 2015 to 31 December 2015. We can see that the VTEC STD of GEO is generally smaller than that of MEO and IGSO. We also find, by comparing the five GEO satellites, that the STD value is related to the satellite elevation to a certain extent, and the satellites with lower elevation have a larger STD. This is related to the uniformity of IGS GIM precision, multipath and measurement noise, and others. It should be noted that the precision of the GIM is lower than that of VTEC12, and it is only proved that the calculation results are correct, but the precision of VTEC12 cannot be assessed.The IGS Working Group on Ionosphere provides global ionosphere map (GIM) products, which are estimated using GPS and GLONASS measurements from global sites. The final IGS ionosphere products have a temporal resolution of 2 h and a spatial resolution of 5 × 2.5° (longitude × latitude), and the GIM precision is 2–8 TECU . Figure In this section, we select three sites named CUT0, SIN1, and JFNG for analysis, as they are located in the southern hemisphere, near the equator, and in the northern hemisphere, respectively. The VTECs are computed using the smoothed code observations during 2013 and 2015. Some analysis results of the ionospheric TEC sequence variation over time are used to demonstrate the characteristics of the GEO satellites in ionospheric monitoring.○The sunspot number increases at the beginning of January and April and at the end of March 2015.○The geomagnetic activity around 17 March 2015 is very strong.○There is moderate intensity geomagnetic activity at the end of December 2015.○Magnitude-8.2 and 7.7 earthquakes occurred on 21 October and 25 November 2015 in Vanuatu and Peru, respectively. The daily maximum VTEC can also reflect the ionization level and is usually used to study the long-term variation of ionosphere and ionospheric anomalies. The above times match the anomalous times of the ionosphere in This article focuses on the advantages of using GEO satellites to monitor the ionospheric TEC. The main advantage of this method is that the IPP of GEO is almost motionless compared to that of IGSO and MEO. A large amount of observations from eight IGS sites selected from the IGS tracking network were used for targeted analysis.The observations of GEO are always continuous in comparison with those of IGSO and MEO satellites. The IPP motion velocity of the GEO satellite is less than 1 m/s, whereas that of MEO and IGSO satellites reaches several tens of meters per second. Combining the analysis of the site coordinates, it was shown that it is impossible to monitor the ionospheric TEC using the BDS GEO satellites in the Antarctic and Arctic regions, as the GEO satellites here are invisible or close to the horizon.A theoretical precision analysis of the method based on the actual observations was performed. It was shown that B1/B2 is the best performance combination, and the precision of VTEC derived from the smoothed code and the raw code is 0.69 TECU and 5.54 TECU, respectively, both of which are, respectively, slightly higher than that of the combination B1/B3 and much higher than that of the combination B2/B3. From the perspective of application, the monitoring results of the CUT0 and JFNG site in 2015 were presented and discussed briefly. The calculated TEC at the fixed IPP of the GEO satellites demonstrates the detailed ionospheric variation characteristics, including the ionospheric variation over time and anomaly monitoring.As the number of available GEO (SBAS system) and tracking sites increase, dual-frequency measurements will increasingly be used for ionospheric monitoring, especially during ionospheric storms, scintillations, and other abnormal phenomena. Research and analysis in this area will continue in the future.


OR6B3 is one of the most highly expressed ORs. Immunohistochemical stainings of retina sections localized OR2W3 to the photosensitive outer segment membranes of cones, whereas OR6B3 was found in various cell types. OR5P3 and OR10AD1 were detected at the base of the photoreceptor connecting cilium, and OR10AD1 was also localized to the nuclear envelope of all of the nuclei of the retina. The cell type-specific expression of the ORs in the retina suggests that there are unique biological functions for those receptors.Several studies have demonstrated that the expression of odorant receptors (ORs) occurs in various tissues. These findings have served as a basis for functional studies that demonstrate the potential of ORs as drug targets for a clinical application. To the best of our knowledge, this report describes the first evaluation of the mRNA expression of ORs and the localization of OR proteins in the human retina that set a stage for subsequent functional analyses. RNA-Sequencing datasets of three individual neural retinae were generated using Next-generation sequencing and were compared to previously published but reanalyzed datasets of the peripheral and the macular human retina and to reference tissues. The protein localization of several ORs was investigated by immunohistochemistry. The transcriptome analyses detected an average of 14 OR transcripts in the neural retina, of which  The odorant receptors (ORs) provide the basis for the detection of volatile odorant molecules in the environment. OR genes were previously determined to be expressed exclusively in the olfactory epithelium . HoweverIn the current study, we are the first to describe the complete expression profile of the ORs in the human retina by RNA-Sequencing (RNAseq) analysis using next-generation sequencing. We also validated the protein expression and the protein localization of several ORs by immunohistochemistry. The identification of the ORs expressed in the human retina provides the basis for the further functional characterization and potential application as therapeutic targets.The RNAseq analysis of human retinae was conducted with anonymized probes from three different donors. For the western blotting analysis and the immunohistochemistry, human donor eyes  with no history of retinal disease were obtained from the Department of Ophthalmology, University Medical Center Mainz, Germany and Department of Ophthalmology, Ludwig Maximilian University, Munich, Germany. We followed the guidelines of the declaration of Helsinki and the study was approved by the local ethics boards of the clinical and the experimental study contributors (Nr. 331-09).GENterprise Genomics  using the Illumina NextSeq500 sequencing platform as paired-end reads with a 101-nucleotide (dataset Retina2) or with a 151-nucleotide (datasets Retina1 and Retina3) length (Supplementary Table S1). We analyzed the mRNAseq data as described previously (1 (accession number: GSE30611), as previously described .For the transcriptome analysis, the RNAs from the human retinae were isolated using the RNeasy Plus Mini Kit  according to the manufacturer’s protocol, including the DNaseI digestion. The mRNA isolation from total RNA and sequencing analysis was performed by eviously . For theeviously . Bowtie,eviously . The BAMeviously . The FPKeviously . We reaneviously  and fromeviously . Six of escribed . The humescribed . The datescribed . All datTo determine a FPKM cutoff value for OR expression, we estimated the background of detection. For this purpose, we used modified gtf-files where the annotated transcripts of the ORs were shifted to random positions in the intergenic regions basically as described by The total RNA from the retinae was reversely transcribed using the iScript cDNA Synthesis Kit  according to the manufacturer’s instructions. The equivalent of approximately 50 ng of RNA was used for each of the RT-PCR experiments. We designed primers that detect approximately 150–450 bp fragments of the OR open reading frame . The PCR was performed under standard PCR-conditions with the Mastercycler ep Gradient S . All experiments were conducted in triplicate.The polyclonal antibody rabbit anti-OR6B2/3 was purchased from Novus Biologicals . It was generated against a synthesized C-terminal peptide derived from human OR6B2. The polyclonal rabbit antibodies against OR2W3, OR5P3, and OR10AD1 were obtained from Sigma-Aldrich . The specificity of OR antibodies was verified using recombinantly expressed rho-tagged ORs in Hana3A cells , or CFTM-640 , respectively. Some of the samples were counterstained with the fluorescein-labeled lectin peanut agglutinin , which specifically labels the extracellular matrix sheath of the cone photoreceptor cells (The two donor eyes were dissected and fixed in melting isopentane (at -168°C) and then cryosectioned as described in or cells  and withTBP) is detected at 7–9 FPKM in the retina samples, whereas the strongly expressed glyceraldehyde-3-phosphate-dehydrogenase (GAPDH) gene reveals an expression value of approximately 2700 FPKM . To test whether the retina was dissected free of contamination with RPE, we evaluated the expression of typical RPE associated gene transcripts, which were relatively weakly or not at all expressed in Retina1–3 . For example, the strongly expressed rhodopsin gene (RHO) had an expression value of ∼3,300–4,200 FPKM . As shown in Figure 1A, the common neural retina marker genes are exclusively expressed in our generated retina samples. In comparison, the typical RPE-associated gene transcripts are relatively weakly or not expressed in Retina1–3 . We further tested the variability of the human retinae transcriptome datasets using the Pearson product moment correlation and identified high correlations (ρ = 0.950–0.982) within our generated retina data  and also between our data and the published data of the peripheral . The quantitative expression values were calculated for each sample based on the number of FPKM. In total, we detected the expression of approximately 17,100 genes (FPKM ≥ 0.1) of the 22,711 genes represented in the gene model. On a rough scale, a FPKM ≥ 0.1 corresponds to a weak expression level, a FPKM ≥ 10 represents a moderate expression level and a FPKM ≥ 100 indicates a high expression level. For example, the weakly to moderately expressed TATA box binding protein . Initially, we identified 11 to 19 different potential OR transcripts  of 374 annotated OR genes in the three human retina datasets . The comparison of the OR expression profiles of the retina with the reference tissues revealed that the majority of potential OR transcripts are absent in reference tissues, excluding the TG and the DRG. Approximately 46% of the identified putative OR transcripts in the retina were also present in the analyzed TG and 30% in the DRG (mFPKM ≥ 0.3).Next, we analyzed the expression of the OR transcripts in the human retinae compared to the reference tissue samples . In addition to the retina, the OR6B3 could also be detected in the TG and the DRG. Using the IGV, we confirmed the predicted expression of the OR6B3 and also validated the expression of both of the 5′UTRs of OR6B3 by RT-PCR with a forward primer located in the identified exon and a reverse primer located in the ORF of OR6B3 . For OR6B2, reads are mapped only at the positions where the sequence is identical to OR6B3 and virtually never at positions that were specific for OR6B2. Therefore, the sequenced reads originate from the OR6B3 transcript and the expression of the OR6B2 transcripts remains unclear. In addition, a detailed analysis of unique mapping reads indicates that OR6B3 but not OR6B2 is expressed in the human retina, which is also supported by RT-PCR analysis  34, pseudogene; OR1Q1 revealed splicing events within their ORF, which are a typical feature of many of the OR-transcripts  and is in the reference tissues only detectable in TG and DRG.Additionally, we also identified that the whole genome region around the ORF of in situ by using cryosections taken through the retinae of two mature donors . The well-defined layering of the human neural retina makes it relatively simple to determine the spatial distribution of proteins in a retinal section even by light microscopy . The indirect immunofluorescence staining of cryosections throughout the two human retinae from both donors was consistent and revealed the expression of all four ORs  in the human retina . To determine the subcellular localization, we counterstained the sections with the nuclear/DNA marker DAPI and with antibodies against diverse molecular markers of cell compartments . For example we used the antibody detecting centrin 3 as a well characterized marker for the connecting cilium, the basal body and the adjacent centriole of photoreceptor cell cilia at the junction of the inner and outer segment . Faint staining was detected in the inner plexiform layer (IPL). Counterstaining with the antibody against calnexin, an ER marker, showed co-labeling in the photoreceptor IS, particularly in the wider cone IS . Additionally, Western blotting analysis confirmed the presence of OR6B2/3 protein expression in the human retina . Counter-staining with the anti-centrin 3 demonstrated the OS localization of OR2W3 in these photoreceptor cells . The low number, the relative proximal position, and the morphology of the according cells  led us to the assumption that these cells were cone photoreceptors . Counterstaining with a FITC-labeled peanut agglutinin (FITC-PNA), a classical marker for the cone photoreceptors specifically staining the extracellular sheath .Indirect immunofluorescence staining using anti-OR2W3 resulted in intense immunofluorescence in a subset of photoreceptor cells . In the photoreceptor layer, OR5P3 was present in the ciliary region (CR) and in the IS of photoreceptor cells . Higher magnification and co-staining with the ciliary marker anti-Cen3 demonstrated the association of OR5P3 with the ciliary base of photoreceptor cells .We found punctate staining of the anti-OR5P3 in all of the layers of the human retina with lower concentrations at the OLM and the OPL . At higher magnification, co-staining with anti-centrin 3 demonstrated that OR10AD1 associates with the base of the photoreceptor cilia . An overlay of the indirect immunofluorescence of anti-OR10AD1 with the fluorescence of the nuclear DNA marker DAPI revealed that the OR10AD1 localizes in the nuclear envelope of all of the nuclei in the human retina . Interestingly, we observed that the most intense indirect immunofluorescence of anti-OR10AD1 associated with the nuclei of the IPL where the pericarya of the bipolar, horizontal and amacrine cells are located. An additional association with nuclei of photoreceptor cells in the outer nuclear layer was occasionally observed (data not shown). Z-scans of stained nuclei revealed that OR10AD1 is predominantly localized in the nuclear envelope and to a less extend in spots within the nucleus .We detected OR10AD1 in the CR and in the nuclei of the outer and the inner nuclear layer, as well as in the GC of the human retina  is predominantly localized in the satellite glia cells (RTP1 and RTP2) were not detectable in human retina, only REEP1, which enhances the cell surface expression of ORs was expressed in retina according RNAseq data  were found to be ectopically expressed exclusively in the human retina, suggesting a specialized function. One of them, OR5P3 is localized to the base of the photoreceptor connecting cilium, which corresponds to the transition zone of prototypic cilia  canonically coupled to the ORs is also expressed in the photoreceptor cells  is comparable to that of ORs (Supplementary Figure Most of the ‘classical’ downstream molecules that are associated with GPCR signaling at the plasma membrane, such as the G protein, adenylyl cyclase and Ca nucleus . Interesor cells . Beside e cortex . Thus, Oe cortex  such as e cortex . InteresFor the first time, we have described the expression of ORs in the human retina. We identified OR6B3 as one of the highest ectopically expressed ORs in terms of its FPKM/TPM value and by its detection at the protein level. We observed that some ORs are expressed in diverse and other in specific cell types or regions of the retina. The specific localizations within the neural retina in general and on the subcellular level of the photoreceptor cells implicate the distinct functions of ORs outside of the olfactory epithelium (i.e., similar to the spermatozoa Wrote the paper: NJ, KW, LG, UW, and CH. Analyzed the data: NJ, KW, and GG. Designed the experiments: NJ, KW, GG, HH, LG, UW, and AK. Conducted the experiments: NJ, KW, LT, MW, CF, DM, and LW.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.


Butt joints of A5052 aluminum alloy and SS400 steel, with a new type of chamfered edge, are welded by means of metal inert gas welding and ER4043 Al-Si filler metal. The microhardness and microstructure of the joint are investigated. An intermetallic layer is found on the surface of the welding seam and SS400 steel sheet. The hardness of the intermetallic layer is examined using the Vickers hardness test. The average hardness values at the Intermetallic (IMC) layer zone and without the IMC layer zone were higher than that of the welding wire ER4043. The tensile strength test showed a fracture at the intermetallic layer when the tensile strength is 225.9 MPa. The tensile value test indicated the average of welds was equivalent to the 85% tensile strength of the A5052 aluminum alloy. The thickness of the intermetallic layers is non-uniform at different positions with the ranges from 1.95 to 5 μm. The quality of the butt joint is better if the intermetallic layer is minimized. The Si crystals which appeared at the welding seam, indicating that this element participated actively during the welding process, also contributed to the IMC layer’s formation. The level of diffusion of Fe in Al will result in the formation of the corresponding phase: Fe3Al, Fe2Al5, FeAl, FeAl2 or FeAl3. Various methods have been used to achieve optimal results when welding aluminum alloys and steel, such as friction stir welding [Aluminum alloys are widely applied in the shipbuilding, aerospace, and automotive industries, as well as many other areas, because of their numerous advantages ,2. Steel welding , laser w welding , resista welding ,9, and u welding ,11. MetaThe materials used in this research include A5052 aluminum alloy sheets and SS400 steel sheets, with a thickness of 5 mm, and aluminum welding wire ER4043 (Al-5Si) with a diameter of 0.8 mm. The chemical compositions of the two base materials and the welding wire used in this research are shown in All sheets used in the experiments were cut to a size of 200 mm × 70 mm, and the surfaces of the base material sheets were cleaned with metal brushes and then with sandpaper before welding. The welding was carried out using an MIG/MAG pulsed welding source, and the welding parameters were a welding intensity of 85–100 A, a welding speed of 4 to 5 mm/s, a welding voltage in the range of 16–18 V, a contact tip to work distance (CTWD) of 8–10 mm, and an argon gas shield rate of 10–11 L/min. The schematic of the MIG welding process and the shape of the new chamfer between A5052 aluminum alloy and SS400 steel is shown in An SHT4000 universal machine was used to test the weld’s tensibility. Seven samples were selected from the total of 15 welded samples with only the welding intensity in the whole experimental process of testing for tensile strength having the same operational condition. For the microstructure of the welding seam and the SS400 steel plate, when welding A5052 aluminum alloy to steel, our study used a welding intensity of 95 A and a welding speed from 3.5 to 4 mm/s, as shown in 3Al, FeAl, FeAl2, Fe2Al5 and FeAl3, which appear during the Fe/Al reaction process. The formation of a new phase is often determined by the thermodynamic conditions: the lower the free energy, the easier the phase forms during the process of multiphase formation. The interface between the steel and Fe2Al5 was smooth, and serrated shapes formed with the interface between the welding seam metals and FeAl3. Furthermore, the formation of new phases were often decided by the thermodynamic conditions and low the free energy. This leads to form process of multi-phase easy. Therefore, the formation of Fe-Al IMC layers could be predicted based on the thermodynamic data of the free energy. This has proved that the phase formed is Fe4Al13 during the chemical reaction between steel and aluminum. 2Al8Si phase, and not a two-chemical-element Fe4Al13 phase.According to the Fe-Al binary phase diagram reported in ,17,18, tThe X-ray mapping of the elements at the intermetallic layer zone between the SS400 steel and the welding seam at the IMC layer zone and without the IMC layer is provided in 2Al8Si phase.Welding dissimilar metals using the new chamfering method was successful on the front side and the bottom side. Because the SS400 steel had a higher melting temperature, it only melted a bit at the surface; the A5052 alloy had a lower melting temperature, so it melted completely.As the welding was done by hand, the thickness of the intermetallic layer was not uniform, ranging from 1.95–5 μm, and formed on the surface of the steel sheet. Minimizing the thickness of the intermetallic layer improved the quality of the welds. The SEM/EDS analysis showed the metallurgical interaction between the welding seam and SS400 steel.The average value of the tensile strength of the specimens was higher than the tensile strength of the welding wire ER4043, at 26.4%, and the average value was equivalent to 85% of the tensile strength of the A5052 aluminum alloy. The average microhardness value at the IMC layer zone and without the IMC layer zone in this research was higher than that of the welding wire ER4043 (56–64 HV), showing that the dynamic load capacity was low and the welds were brittle.Cracks, resulting from the use of high power in the welding process, were found between the welding seam and SS400 chamfered steel when the IMC layer was too thick.The welding of two dissimilar metals, A5052 aluminum alloy and SS400 steel, was conducted using MIG with ER4043 filler metal and the new chamfering method. The tensile strength, microhardness, and microstructural characteristics were investigated. The conclusions drawn from this research can be summarized as follows:


Posidonia oceanica (PO), a dominant Mediterranean seagrass, were produced by simple melt mixing and characterized in terms of thermal stability, morphology and rheological/mechanical properties. In view of their potential application in marine environments, degradation of the developed composites was evaluated under simulated and real marine environmental conditions for 1 year. Using 10 wt % of acetyl tributyl citrate (ATBC) as a plasticizer, smooth processing was achieved for up to 30 wt % of PO fibers, despite the reduction of the melt fluidity observed with increasing fiber loading. The tensile modulus slightly increased (from 2 to 2.4 GPa) while the tensile strength and the elongation decreased  by increasing the PO fiber content from 0 to 30 wt %. Interestingly, the impact resistance of the composites increased with the increasing of the PO content: the Charpy’s impact energy increased from 3.6 (without fiber) to 4.4 kJ/m2 for the composite with 30 wt %. The results of the aerobic biodegradation under simulated marine conditions showed that the presence of PO fibers favored the physical disintegration of the composite increasing the biodegradation rate of the polymeric matrix: after 216 days, the composite with 20 wt % PO fibers showed a biodegradability of about 30% compared to 20% of the composite without fibers. Under real marine conditions, the specimens containing PO fibers showed higher weight losses and deterioration of tensile properties compared to those without fibers. Presumably, biodegradation occurred after colonization of the specimen, and the specimens with 20 wt % PO fibers showed well-developed biofilm consisting of bacteria and fungi on the surface after only 3 months of incubation in marine sediments, unlike the no-fiber specimens. Consequently, the persistence of an adequate mechanical performance for a relatively long period (1 year), due to a moderate rate of biodegradation in the marine environment, make the developed PHBV/PO composites particularly suitable for the production of relatively low-cost and biodegradable items which are usable in the sea and/or sand dunes, increasing the market opportunities for biopolymers such as PHBV and, at the same time, finding an eco-sustainable valorization for the PO fibrous residues accumulated in large quantities on Mediterranean beaches, which represents a problem for coastal municipalities.In order to produce sustainable, bio-based and highly biodegradable materials, composites based on poly (PHBV) and fibers of  Posidonia oceanica (PO), have also been used as filler in the production of “green” composites [Posidonia oceanica is a Mediterranean endemic species that covers 60% of the seabed from 0 to 40 m depth [Posidonia oceanica fibers is similar to that of lignocellulosic materials from terrestrial plants consisting mainly of cellulose, hemicellulose and lignin. Large amounts of this material in the form of balls (egagropili) as well as whole plant fragments are deposited along many coastal beaches after storms. Stranded Posidonia oceanica residues play an important ecological role for the protection of coasts from erosion [Posidonia oceanica wastes in compost production, up to a maximum of 20 wt % by fresh weight of the composting mixture. However, the high content of sand and salinity represent the main obstacles to the large use of this biomass for composting. Thus, the search for sustainable and cost-competitive alternatives to landfilling or composting is strongly encouraged.The world petro-plastic production reached about 335 million tons (Mt) in 2016 and is expected to double again over the next 20 years ,5. Polyhmposites ,25,26,27mposites . Posidon m depth . The che erosion , but thePosidonia oceanica were produced by melt mixing, processed by injection extrusion and characterized in terms of processability, rheological properties, thermal stability and mechanical performance. In order to improve the processability and the ductility of PHBV the addition of a plasticizer was necessary. For this reason, acetyl-tri-n-butyl citrate (ATBC) was used, being one of the most efficient plasticizers proposed for poly(hydroxybutyrate) (PHB) and its blends with PLA [In the present work, composites based on poly and fibers of with PLA ,32,33,34with PLA , acceptewith PLA  and is d® . It is a poly (PHBV), with 5 wt % valerate content. PHBV is characterized by a melting point of 145–150 °C, a density of 1.25 g/cm3, and a melt flow index of 10–20 g/10 min . Posidonia oceanica (PO) balls (egagropili) were collected on a beach of the Ligurian Sea . They were washed with tap water to eliminate sand and other contaminants and then dried at 50 °C in an electric oven for 24 h. The ensuing material was milled using a lab-scale mill and sieved with a 500 µm sieve. The final length of the fibers was in a 1.5–2 mm range and the aspect ratio was in the 7–10 range. ATBC from Sigma Aldrich  was selected as plasticizer for PHBV. In addition, it is a bio-based, biodegradable and an almost colorless/odorless oily liquid. Calcium carbonate OMYACARB®2 provided by OMNYA®  with fine grain size distribution (12 μm) was used as filler in order to reduce the cost of the final product and facilitate the removal of the product from the mold.The thermoplastic matrix used in this work is PHI002™ supplied in pellets from Naturplastw/w PHBV/CaCO3 as polymeric matrix and 10 wt % ATBC on the total weight. The nomenclature of the samples was as follows: PCA for the composite without PO fibers (PHBV/CaCO3/ATBC) and PCA10, PCA20 and PCA30 for the composites containing the different fiber loadings: 10, 20 and 30 wt % of PO fibers, on the total composite weight, respectively. The composites were prepared by mixing the different components and then the ensuing mixtures were processed in a Thermo Scientific Haake Minilab Micro-compounder (Minilab), a co-rotating conical twin-screw extruder. The extruder operating conditions adopted for all the formulations are reported in Composites containing 10, 20, and 30 wt % PO fibers, with respect to the total weight, were produced using 95/5 The extruded composite filaments were cut to obtain pellets used for the subsequent thermal characterization and the lab-scale aerobic biodegradation test in seawater. For each formulation, specimens for the tensile test  and for the Charpy’s impact test (bars 80 × 10 × 4 mm) were produced by feeding the molten material directly from the Minilab to a Thermo Scientific HAAKE MiniJet II . Dog-bone specimens were also used for the degradation test in natural marine mesocosms.3 s−1. The energy which is dissipated during fracture is calculated from the height of the pendulum weight before and after impact. The dissipated energy is reported as the impact toughness per unit fracture cross-section (J/m2).Thermal properties of the starting materials and PHBV/PO composites in the form of pellets were evaluated by thermogravimetric analysis (TGA). Thermogravimetric measurements were carried out on about 20 mg of sample using a Q500 TGA , under nitrogen flow (100 mL/min), at a heating speed of 10 °C/min from room temperature to 600 °C. In addition, the isothermal stability of the raw materials at the processing conditions (170 °C) under nitrogen for 5 min has been also evaluated using an isothermal mode. The TGA measurements were carried out in duplicate. Tensile tests were performed on the injection molded Haake Type 3 (557–2290) dog-bone tensile bars of composites in accordance with ASTM D 638. Stress–strain tests were carried out at room temperature, at a crosshead speed of 10 mm/min, by an Instron 5500R universal testing machine  equipped with a 10 kN load cell and interfaced with a computer running the Testworks 4.0 software . Impact test was carried out on V-notched specimens using a 15 J Charpy pendulum  following the standard method ISO 179:1993. In the Charpy test, the load is provided by the impact of a weight at the end of a pendulum. A crack starts at the tip of the V-notch and runs through the specimen. The material deforms at a strain rate of typically 10For each mechanical test, at least five replicates were tested for each sample. Morphological analysis was carried out by scanning electron microscopy (SEM), using a JEOL JSM-5600LV  both on the cross-section of the dog-bone tensile specimens fractured in liquid nitrogen and on the cross-section of the specimens fractured after the tensile tests in order to evaluate the dispersion of the fibers into the polymeric matrix and the fiber/matrix interactions, respectively.In view of the possible application of the PHBV/PO composites in marine environments, aerobic biodegradation and degradation tests were performed under simulated marine conditions and in real marine mesocosms.2 evolved from bioreactors containing the sample (pellets) placed at the seawater/marine sediment interface. The setup of the system used is shown in The aerobic biodegradation of the composites in simulated marine conditions was evaluated in accordance with a modified version of the ASTM D6691 method based on the measurement of the COa and b contained 250 mL of a 5 M NaOH solution to remove CO2 from the air and the flask c 200 mL of a 0.04 M Ba(OH)2 solution, used to indicate the complete removal of CO2 from the air. The flask e contained 40 mL of a 0.1 M Ba(OH)2 solution to absorb the CO2 developed in the bioreactor during the degradation process. The amount of CO2 developed was calculated by the consumption of Ba(OH)2 in the flask e, determined by titration, carried out twice a week, with 0.1 M HCl using phenolphthalein as indicator. The amount of CO2 developed in each bioreactor was calculated according to the following equation:CO2 is the CO2 evolved from the bioreactor, VBa(OH)2 is the volume in L of Ba(OH)2 (40 mL) in flask e at the beginning of the run, VHCl is the volume in L of HCl needed for titration of Ba(OH)2 at the end of run, CBa(OH)2 and CHCl are the concentration of Ba(OH)2 and HCl, respectively, in mol/L, 44 is molecular weight of CO2. Filter cellulose paper (Whatman n.40) was used as positive control and flasks containing only seawater and sediment as blanks. The biodegradability of each sample was calculated as percentage (corrected for the blank flask emissions) of the overall theoretical amount of CO2 (ThCO2) that could be released, calculated on the basis of the initial organic carbon content of the sample, as shown below:The bioreactor contained 100 g of marine sediment (fine sand), 150 mL of sea-water and about 300 mg of composite sample (pellets). Seawater and the marine sandy sediment were collected in a coastal area near Rosignano Solvay , at 50 cm depth . The test was conducted at room temperature in 300 mL flasks connected to each other with tubes where an air-flow rate of about 100–120 mL/min was fed through a pump. The flasks Being an innovative natural fiber for composites production, and in order to evaluate the effect of fiber on composite degradation, the test in marine water was carried out even on PO fibers. For each type of sample, the test was quadrupled and the mean values were considered.3) with continuous natural seawater flow equipped following a protocol, previously established for successfully growing seagrasses [The changes in the weight and in the mechanical properties of dog-bone tensile specimens were evaluated over the time in an outdoor marine culture system, located at the Mariculture Center of Rosignano Solvay  . The system consisted of tanks  and a scanning electron microscope  to check for the formation of biofilm and the presence of degradation signs and microorganisms on their surface. For the SEM analysis, the samples were fixed in 2% OsOIn the processing of a polymeric composite, it is important to know how much energy is required to bring the mixture from an initial state to a homogeneous melt and how much time this process requires. The processing behavior of the investigated composites was quantified by the torque at the different mixing times and the end of mixing. The average torque–time curves obtained at 170 °C and a rotor speed 100 rpm for the PCA and PHBV/PO composites are reported in w/w of ATBC/ PHBV increased from 0.13 to 0.175 compensating for the effect of the fiber content increase.The curves give indications on the mixing behavior and on the energetic effects of the process. The incorporation of the PO fibers in the PHBV based polymeric matrix increased the torque and consequently the energy required for the melt mixing. All the PHBV/PO composites showed the same final torque value of about 66.5 Nm: this can be attributed to the fact that, going from PCA10 to PCA30, the ratio The thermal stability of PO fibers, PHBV, ATBC and the developed composites in terms of thermogravimetric (TG) and their derivative (DTG) curves is shown in The thermal stability of the PHBV, PO fibers and ATBC at the composite processing temperature (170 °C) is shown in The mechanical properties of the composites, evaluated by tensile and Charpy’s impact tests, are reported in Posidonia oceanica fibers. The observed behavior is typical of particle-filled polymeric matrices with poor or no compatibility between the components, meaning that stress transfer phenomena cannot occur and the filler particle becomes a stress concentrator leading to brittle fracture [As shown, the Young’s modulus slightly increased and the elongation at break significantly decreased with increasing fiber loading, due to the stiffening effect induced by lignocellulosic fillers , while tfracture ,41.In order to better analyze the tensile results, SEM analysis was performed on the cross-section of the specimens before the tensile test and on the fractured section after tensile test. As example, the SEM images of the PCA and PCA20 specimens are reported in As shown, in the unbroken PC20 specimen, the PO fibers are quite homogeneously distributed within the thermoplastic matrix. The interfacial interactions between the fibers and the matrix were not sufficiently strong to maintain the cohesion during the tensile tests, as shown in the broken specimen section where a significant fiber pullout is evident. The same results were observed also for the samples PCA10 and PCA30, which are not shown here for brevity.As shown in The aerobic biodegradation curves obtained from the lab-scale test under simulated marine environmental conditions and the temperature recorded during the test are reported in 2 (ThCO2) based only on the carbon content of PHBV and ATBC. In this way, the effect of the PO fibers on the biodegradation rate of the polymeric matrix was more evident, as shown in At the end of the test (216 days), the biodegradation of the filter paper was about 70%, while the composite PCA20 reached a value of about 30% higher than that without PO fiber (PCA) and still growing. Therefore, the “relative biodegradation”, i.e., the biodegradation of the test material relative to the positive benchmark , was about 40%. Considering the slow degradation rate of lignocellulosic PO fibers in natural environments that was confirmed also by this test , and also showed a well-developed biofilm consisting of diatoms, bacteria and fungi on the PCA20 specimen surface. The Posidonia oceanica fibers were incorporated in a thermoplastic matrix based on PHBV and ATBC to produce melt processable and biodegradable composites for specialized applications in marine environments. The resultant composites were characterized in terms of processability, thermal/mechanical/morphological properties and biodegradability under simulated and real marine environmental conditions.Different amounts  of Posidonia oceanica fibers in the composites accelerated the biodegradation of polymeric matrix. After about 7 months in marine sediment, pellets with 20 wt % of PO fibers showed a biodegradability of 30%, corresponding to a relative biodegradability, with respect to cellulose, of 40%. The degradation test in marine mesocosm showed that after 3 incubation months in marine sediments, an evident microbial community consisting of bacteria and fungi colonized the surface of the composite specimens containing PO fibers. During the 12 months of testing, the specimens without fibers maintained their tensile properties almost constantly, while those with 20 wt % PO fibers showed a strong decay of their mechanical performance, and after 10 months it was not possible to determine them. These findings confirm that the presence of PO fibers, due the poor matrix/fiber adhesion, favored the physical degradation of the specimens accelerating the biological attack with a consequent decay of the mechanical properties, and that the degradation process is influenced by the seawater temperature: higher temperatures led to higher degradation rates.The processing of the composites at up to 30 wt % of PO fiber content did not create any difficulty, and the obtained composites showed good thermal stability and mechanical properties, especially in terms of stress at break and impact resistance. The biodegradation test results in the simulated marine environment showed that the presence of Posidonia oceanica is technically feasible by conventional extrusion and represents an eco-sustainable valorization of these residues which accumulate on sandy beaches, contributing to solving a real environmental and management problem. In addition, the maintenance of the mechanical properties for a relatively long period (a year) makes the developed composites particularly suitable for the production of biodegradable and relatively low-cost items usable in the seawater such as restoration tools and, after the disintegration of the polymeric matrix, the residual PO fibers would return to their native habitat.On the basis of the results, it can be concluded that the production of composites based on PHBV and fibrous wastes of


Universidade do Estado do Pará in 2015.  To evaluate the impact of atopic dermatitis on the quality of life of pediatric patients in the age group of 5-16 years, and their parents, assisted at the Dermatology Department of p<0.05 significant.  A cross-sectional study including 51 patients and their guardians, to whom two questionnaires about the quality of life were applied, the Children’s Dermatology Life Quality Index (CDLQI) and the Dermatitis Family Impact (DFI). To evaluate the severity of the disease, the researchers applied the Severity Scoring of Atopic Dermatitis (SCORAD) index. The Pearson Product-Moment Correlation Coefficient (PPMCC) evaluated the correlation between CDLQI, DFI, SCORAD, and the contingency coefficient C evaluated the association between the qualitative variables, considering p<0,001). Of the patients, 55% were female. The average age was 9.5±3.2 years, and 41% had family income up ≤1 minimum wage. The average score was 5.4±5.1 for CDLQI, 6.6±4.5 for DFI, and 28.3±19.8 for SCORAD. The correlation among the scores CDLQI, DFI, and SCORAD was significant by the PPMCC ( Atopic dermatitis affects the quality of life of both children and their guardians, and indicates the importance of including the study of quality of life as a complement to clinical evaluation. Atopic dermatitis (AD) is a chronic inflammatory dermatosis of multifactorial etiology, characterized by moderate-to-intense pruritus. This condition evolves to outbreaks, and has a hereditary allergic character.,In the past three decades, the number of patients with AD has doubled - or even tripled - in most parts of the world, constituting a major public health problem, especially in industrialized countries.In Brazil, the prevalence of AD ranges according to the affected age group and Brazilian region analyzed. The North and the Northeast have a slight higher number of cases, and in all places, the prevalence is higher among younger children (6 and 7 years old). The International Study of Asthma and Allergy Diseases in Childhood (ISAAC) was conducted in Brazil and pointed to mean prevalence of AD of 7.3%, expressed as severe in 0.8% of the patients in the age group from 6 to 7 years. At the age of 13 and 14 years, the mean prevalence of AD was 5.3%, and severe AD, 0.9.The diagnosis of AD is essentially clinical and is based on clinical-laboratorial diagnostic criteria established by Hanifin and Rajka.,Skin conditions have a negative impact on emotional status, on social relationships and on daily activities, thanks to the stigma caused by the appearance of the lesions.In this context, this study aimed at measuring, through validated questionnaires, the impact of AD on the quality of life of pediatric patients in the age group of 5-16 years and their guardians, assisted in a reference pediatric dermatology service located in Eastern Amazon.This is a descriptive, cross-sectional study, including pediatric patients in the age group of 5-16 years, of both sexes, diagnosed with classic clinical criteria of ADFurther to the approval in UEPA’s Ethics Committee, in February 2015, report number 960,962, the study was performed with the consent of the institution and the patients and/or their guardians, through an informed consent form and an informed assent form for adolescents in the age group of 12 to 16 years.The severity of the disease was analyzed using the Severity Scoring of Atopic Dermatitis Index (SCORAD). Its assessment is based on the affected surface, and is calculated by using the rule of 9, the same used for burns . It is also based on the intensity of the eczema, by the presentation of elementary lesions , and on the repercussion of subjective symptoms of pruritus and sleep loss.,Two questionnaires were used to assess the quality of life: the Children’s Dermatology Life Quality Index (CDLQI) and the Dermatitis Family Impact (DFI) both English and validated in the United Kingdom.The CDLQI, validated to spoken Portuguese in Brazil,The DFI helps to measure how much family life is impacted by a child with AD. It is designed to be filled out by the children’s guardian and has ten questions, all referring to the week before and related to housework, preparation of food, preparation and feeding, sleep, family leisure activities, expenditure, tiredness, emotional distress, and relationships. It was translated and culturally adapted to Brazilian Portuguese.The sample was characterized by descriptive and inferential statistical methods. Qualitative variables presented Gaussian distribution, by the methods of D’Agostino-Pearson. Pearson’s linear correlation tests were used, as well as the contingency coefficient C for the correspondence between instruments CDLQI, DFI, and SCORAD. Alpha error was established at 5% for the rejection of a null hypothesis. Statistical processing was performed with BioEstat 5.3.In the sample comprising 51 patients, 55% were girls and 45% were boys, with mean age of 9.5±3.2 years, ranging from 5 to 16 years. By categorizing the sample in age groups, it was possible to observe that 51% was in the age group of 5-9 years old, and 49% were aged between 10 and 16 years. The most common family income was up to one minimum wage (41.2%), followed by those with income from two to five minimum wages (39.2%).bullying) (0.59±0.47), sleep (0.59±0.45), and leisure activities (0.57±0.40). When classified by domains, the highest score was that of symptoms and feelings (0.87), followed by sleep (0.59) and leisure (0.55). Instruments of data collection presented the following means and standard deviations: CDLQI=5.4±5.1; DFI=6.6±4.5; and SCORAD=28.3±19.8. By assessing the quality of life of the children, CDLQI scored mostly the following specific questions (mean±standard deviation): symptoms (1.06±0.41), feelings (0.69±0.45), sports (0.65±0.48), personal relationships (p<0.001 (highly significant). It leads to the tendency of simultaneous moderate SCORAD and weak CDLQI (25.5%). Complementarily, the analysis of numerical scores obtained in each instrument (CDLQI and SCORAD) was conducted by Pearson’s linear correlation, which resulted in p<0.001* (highly significant), certifying the existence of positive and moderate correlation (r=0.680) between the scores of the instruments CDLQI and SCORAD (The correlation between the severity of the disease (SCORAD) and quality of life (CDLQI) was first analyzed according to the classification in qualitative variables , using the contingency coefficient C, which led to d SCORAD .p=0.078 (not significant). That is, it was not possible to find a qualitative classification chart of the conjoint analysis of SCORAD and DFI (p<0.001*) between the scores of the instruments DFI and SCORAD.The evaluation of the adjustment between severity of the disease (SCORAD) and quality of life of the guardians (DFI), demonstrated as categorical variables, was shown by the contingency coefficient C, which resulted in  and DFI . The anap-value=0.012*) for the simultaneous occurrence of weak effect on the quality of life of the patient and moderate on the quality of life of the guardian (19.6%). The analysis of numerical scores of each instrument (CDLQI and DFI) by the Pearson correlation showed the existence of positive and moderate correlation  between the scores of both instruments.The correlation between the quality of life of the patient (CDLQI) and the guardian (DFI) was assessed by the contingency coefficient C for categorical variables, obtaining significance (The drugs mostly used by the patients were emollients (56.9%), followed by topical steroids (51%) and systemic anti-histaminic (21.6%). Among topical steroids, the most frequent was mometasone furoate, a potent corticosteroid.This study demonstrated the correspondence between the severity of the disease (SCORAD) and the quality of life of the patient (CDLQI) and the respective guardian (DFI).Most children did not use any medication, which differed from the reports of another study, conducted with a sample of children living in Europe.The emollient was mostly used, since dry skin is very common in AD, besides being a diagnostic criterion. In this sense, emollients are part of the atopic treatment to fight xerosis, and can also have an effect on pruritus and pain.The article of CDLQI validationThis study showed similar results in relation to the questionnaires applied in Korea, in a dermatological clinic affiliated to a university hospital with 197 children,By classifying CDLQI in domains, another study - Brazilian - conducted in Porto Alegre (RS),A study carried out in a tertiary center obtaines a mean SCORAD index of 36 (standard deviation: 16.2),,The correlation between DFI and CDLQI using the Pearson correlation coefficient was positive and moderate, in accordance with the Brazilian and the Swedish studies, which also pointed to a significant correlation between these scores.In this study, most children fit the category “weak effect” on the quality of life and most guardians suffered moderate to very high effect.The education of all individuals involved in children care is essential to handle AD. It is important to provide simple and clear information, without ambiguities, with the objective of reducing the negative impact on the quality of life of the family, since the lack of information about the disease and its treatment increases parental anxiety and makes it more difficult to adhere to the treatment and to general care, essential for therapeutic success.Another study using SCORAD and DFI as tools demonstrates that the quality of life of the family is correlated with the severity of AD in the child in an inversely proportional manner. That is, the higher the SCORAD, the lower the quality of life of the family, as shown in this study.An investigation about AD in the family environment concluded that the quality of life of the family was deeply related to the severity of AD, more than the quality of life of the children, pointing out to the deep impact of the condition on the family, in accordance with this study.There is a positive and moderate correlation (r=0.680) between the scores of CDLQI and the SCORAD index, as shown in a study conducted in the United Kingdom with 116 children, obtaining a significant correlation between the instruments in the two visits in which they were applied.The negative impact of AD on the lives of children, especially those with more severe conditions, calls the attention to the long-term effect caused by this disease, especially on the children’s behavior and development. So, these results bring out the possibility of using CDLQI as an extra measure to assess the disease in clinical practice,The observation of the correlation between the severity of the condition and the quality of life shown in this study was also confirmed in Montes Claros (MG), with children aged between 6 months and 5 years.The authors recognize that this study had important limitations. Concerning the low sample power, the convenience sample was formed by 51 children of a target-population composed of 120 children. There was some restriction concerning the time frame for data collection (six months). The sample was taken from a single reference service, located in the metropolitan region of Belém (PA), lacking representativeness from other places in the Amazon region. Besides, the scale reading was required for some children who were not literate, and, in that case, the interviewer’s intermediation may have interfered in the understanding of the questions from the children approached in this study.It is believed that more studies on the quality of life of patients with AD would be beneficial to establish multidisciplinary approaches , aiming at elaborating strategies of treatment and promoting better control of the disease.


Presence of voids at root canal wall‒apical seal material interface gives rise to the entrapment of toxins and microorganisms, which might have a relationship with post treatment disease. The present study was carried out to evaluate the effect of different mixing  and placement  methods of Calcium-enriched Mixture (CEM) cement on the number and dimensions of voids in the apical plug in simulated apexification models.P<0.05.A total of 80 human maxillary central incisors with mature apices were selected. After simulation of the open apices, the teeth were divided into 4 groups (n=20) based on the mixing and placement techniques of CEM cement: group 1, manual mixing‒manual placement; group 2, manual mixing‒manual placement in association with indirect ultrasonic technique; group 3, ultrasonic mixing‒manual placement; and group 4, ultrasonic mixing‒manual placement in association with indirect ultrasonic technique. The samples were placed within gypsum sockets in which the periodontal ligament was reconstructed with polyether impression material. After placement the apical plugs, a wet piece of cotton was placed on canal orifices, followed by dressing with Cavit. The samples were incubated at 37°C and 100% relative humidity for 7 days. Then the voids between the material and root canal walls were counted with the CBCT technique. The void dimensions were scored with the following scoring system: score 1, no voids; score 2, the void size less than half of the size of the evaluated cross-section; score 3, the void size larger than half of the size of the evaluated cross-section. Statistical analyses were carried out with chi-squared and Fisher’s exact tests. Statistical significance was defined at p<0.05). The differences in the number of voids between groups with similar mixing technique and different mixing techniques (i.e. groups 1 and 3 and groups 2 and 4) were not significant (p>0.05). Void dimensions in all the study groups were in score 2 category and no score 3 was recorded in the study groups.The maximum (7) and minimum (2) number of voids were detected in groups 1 and 2, respectively. The difference between these two groups was statistically significant (Under the limitations of the present study, manual placement in association with indirect ultrasonic technique was a proper technique to improve the quality of apical plug, considering the decrease in the number of voids. Key words:Apical plug, CEM cement, void. Calcium-enriched Mixture (CEM) cement is a biomaterial, consisting of different calcium compounds; it has several applications in endodontics and is used as an apical plug in the apexification of mature permanent teeth ,2. A matThe careful delivery of a material used as apical plug is very important clinically, considering the limitations in relation to the accessibility and visualization. One of the techniques suggested to create a denser obturation is the use of ultrasonic vibration energy ,7. StudiPowder-to-liquid ratio and porosity might affect the mechanical properties of cements used in dentistry. Therefore, the mixing and placement techniques are key factors affecting the performance of dental materials .Evaluation of previous investigations into the effect of mixing technique on various properties of CEM showed that mixing with an ultrasonic tip increases its flow and working time; however, it decreases the setting time, compressive strength and film thickness ,10. MixiIdentification of voids is important clinically and evaluation of voids at root canal wall‒material interfaces is a well-established technique for the evaluation of the quality of obturation ,13. RadiThere is no study available on simultaneous evaluation of the effects of various mixing and placement techniques on the quality of CEM apical plugs. This study was therefore undertaken to measure the voids in CEM apical plugs with the CBCT technique by considering the parameters mentioned above.Eighty human maxillary central incisors with straight and mature roots were selected. The tooth samples were free of cracks and fractures. The tooth crowns were cut away at CEJ using a diamond saw  under water spray to achieve 12 mm of the root length. Then 3 mm of the root was removed from the apical end to leave 9 mm of the root length in all the tooth samples.-Simulation of periodontal ligament The roots were coated with molten wax, followed by mounting in gypsum blocks. After the gypsum  set completely, the wax was eliminated with hot water, which gave rise to a gypsum socket. The socket was filled with polyether impression material  and the roots were placed within it. After the polyether impression material set, the roots were removed from the sockets.-Root canal preparation and simulation of open apex modelThe root canals were instrumented with #5, #4, #3, #2 and #1 Gates-Glidden drills  using the crown-down technique in order to simulate apexification. To this end, #5, #4, #3 and #2 drills were inserted into the root canals up to 3, 5, 7 and 9 mm, respectively. To create an open apex, #1 drill was moved 1 mm through the apical foramen once without any resistance. Then the entire length of a #40 RaCe rotary file  with 10% taper was inserted into the root canal through the apical foramen. A total of 5 mL of 0.5% NaOCl solution was used for irrigation during instrumentation. At the end of instrumentation, the smear layer was removed with 5 mL of 17% EDTA. A total of 5 mL of normal saline solution was used for final irrigation.-Placement of the apical plugThe samples were randomly assigned to 4 groups (n=20) in terms of the CEM mixing and placement techniques as follows:Group 1: manual mixing‒manual placementGroup 2: manual mixing‒manual placement in association with indirect ultrasonic Group 3: ultrasonic mixing‒manual placementGroup 4: ultrasonic mixing‒manual placement in association with indirect ultrasonic In all the study groups, CEM was mixed following manufacturer’s instructions at a powder-to-liquid ratio of 3:1, with a mixing time of 15 seconds, to achieve a thick consistency. In group 1, subsequent to mixing the material, an MTA carrier was used to transfer the material incrementally into the root canal; the material was condensed with a hand plugger up to the desired length and continued until the apical plug measured 3 mm in length. In group 2, a similar technique was used; however, after condensing the material with a hand plugger an ultrasonic tip was placed in contact with the plugger for 2 seconds so that an indirect vibratory motion was applied to the material. The lowest power settings of the ultrasonic unit were used. In groups 3 and 4, the material was mixed with the ultrasonic tip for 5 seconds; then in group 3, similar to group 1, and in group 4, similar to group 2, the material was placed in the root canal. A wet piece of cotton was placed at root canal orifices and the samples were dressed with Cavit. Then the samples underwent incubation at 37°C and 100% relative humidity for 1 week.-Evaluation of the samples with the CBCT techniqueEach root sample underwent CBCT examination with the use of a Newtom VGI unit  at axial and cross-sectional views by an experienced radiologist. This CBCT unit delivers a conical x-ray beam and has a flat-panel detector, with 1536×1920 and 127×127 pixel sizes, a pixel depth of 14 bits, a rotation of 360°, a scan time of 18 seconds and a kVp of 110. NNT Viewer software program version 2.17 carried out the initial and final reconstructions. The exposure conditions were set automatically. Data collected from the CBCT examinations were entered into the NNT Viewer software program version 2.17. The images were displayed on a 19-inch LCD monitor  with a resolution of 1024×1208 pixels and 32 bits in a dimlylit room. The number of voids at material‒root canal wall interfaces was counted in all the samples and recorded in terms of the number of voids in 20 samples in each group. The following scoring system was used to characterize the dimensions of the voids . Groups 1 and 3 and groups 2 and 4 did not exhibit any significant differences in the number of voids (p>0.05). Evaluation of the dimension of the voids showed no score 3 in any of the study groups and the dimensions of all the bubbles conformed to score 2, (score 2, .The present study was undertaken to evaluate the effect of different mixing and placement techniques of CEM cement on the number and dimensions of voids in the apical plug. The results showed the positive and significant effect placement of the plug with indirect application of ultrasonic technique in association with the manual technique on decreasing the number of voids in the apical plug. However, the mixing technique had no significant effect on the quality of the apical plug. In other words, in groups with identical placement technique, there were no significant differences in the number and dimension of voids with hand and ultrasonic mixing techniques.Placement of an apical plug in a tooth with an open apex is a technique-sensitive process due to the absence of an apical stop and limitations in visibility and access and it is always possible for voids to form between the apical plug and the root canal walls. These voids provide a path for leakage and create a space for proliferation of microorganisms, compromising the seal and paving the way for post treatment disease ,6,17.In the present study, the number and dimension of voids in the apical plug between the material and the root canal wall were evaluated with the use of the CBCT technique in the axial and cross-sectional vies at 0.1-mm accuracy. In two similar previous studies on the quality of MTA obturation, light microscopy, radiography  and weigA method suggested for improving the density and homogeneity of the apical plug is to use the vibration energy during placement and packing of the material, which re-arranges the particles and creates a denser mass by creating compressive impulses . A previet al. (The results of the present study are in contrast to those of a study by Aminshariae et al. , in whicet al. . In the One of the differences between the present study and the two studies mentioned above was the apical plug material. In the present study, CEM was used but in the studies mentioned above, MTA was used. Comparison of the properties of these two materials in previous studies has shown the easier handling and higher flow of CEM compared to MTA ,18.Apart from the placement technique, another parameter evaluated in the present study, which was not taken into account in previous studies was the mixing techniques of the material before its placement.Previous studies have shown the effect of mixing technique on a number of physical properties of biomaterials such as CEM -12,18,19One of the limitations of the present study was the absence of curved canals. It is suggested that curved canals be used in future studies. In previous studies, the effect of indirect ultrasonic placement technique on increasing the density of the obturation was more evident in curved canals compared to straight canals .Under the limitations of the present study, it can be concluded that when CEM is used as an apical plug, it is recommended that ultrasonic mixing and placement with manual condensation in association with indirect ultrasonic energy be considered in a short time and with minimum power.


Long-term potentiation (LTP) is a specific form of activity-dependent synaptic plasticity that is a leading mechanism of learning and memory in mammals. The properties of cooperativity, input specificity, and associativity are essential for LTP; however, the underlying mechanisms are unclear. Here, based on experimentally observed phenomena, we introduce a computational model of synaptic plasticity in a pyramidal cell to explore the mechanisms responsible for the cooperativity, input specificity, and associativity of LTP. The model is based on molecular processes involved in synaptic plasticity and integrates gene expression involved in the regulation of neuronal activity. In the model, we introduce a local positive feedback loop of protein synthesis at each synapse, which is essential for bimodal response and synapse specificity. Bifurcation analysis of the local positive feedback loop of brain-derived neurotrophic factor (BDNF) signaling illustrates the existence of bistability, which is the basis of LTP induction. The local bifurcation diagram provides guidance for the realization of LTP, and the projection of whole system trajectories onto the two-parameter bifurcation diagram confirms the predictions obtained from bifurcation analysis. Moreover, model analysis shows that pre- and postsynaptic components are required to achieve the three properties of LTP. This study provides insights into the mechanisms underlying the cooperativity, input specificity, and associativity of LTP, and the further construction of neural networks for learning and memory. Learning and memory are fundamental mental processes that are critical for adaptation and survival  channels  and P2 (n2 synapses) (here n1+n2 = n), which can deliver different stimuli. Each synapse consists of three components: presynaptic axon terminal, synaptic cleft, and spine on the postsynaptic cell. Figure In this study, we considered a hippocampal pyramidal neuron (PN) model with 2+ increase due to the influx through NMDA receptors (NMDARs) to trigger downstream signaling pathways -dependent protein kinase II (CaMKII), which in turn phosphorylates the AMPA receptor (AMPAR) glutamate receptor 1 (GluR1) subunit and produces the GluR1 insertion, resulting in an enhancement of AMPAR-mediated transmission and synaptic strength at the activated synapse   receptor in the postsynaptic cell membrane. The phosphorylation of TrkB receptors are activated by binding to BDNF in the cleft   extracellular signal-regulated kinase (ERK)  and excitatory postsynaptic current (EPSC).n1 synapses and the P2 pathway with n2 synapses, and applied different protocols to the two pathway synapses. In simulations, we assumed n = 40 and n1 = n2 = 20 when not noted specifically. Experimentally, the persistence of BDNF-TrkB signaling and the contribution to LTP induction and maintenance is highly sensitive to the pattern of synaptic stimulations  in the P1 pathway receives a stimulus of 100 Hz for 1 s;all synapses in the P1 pathway receive a stimulus of 100 Hz for 1 s;all synapses in the P2 pathway receive a weak stimulus of 5 Hz for 4 s; synapses in the P1 pathway receive a strong stimulus of 100 Hz for 4 s, and all synapses in the P2 pathway receive a weak stimulus of 5 Hz for 4 s.Numerical simulations were performed with MATLAB. The differential equations were solved using the Euler scheme with a time step of 0.01 ms. The injection of a short current pulse into the presynaptic terminal elicits a single action potential , and there was no change in the amplitudes of EPSP and AMPA-mediated EPSC in synapse 1 at 5 h after simulation Figures . Next, wMoreover, when we applied the protocol 2, the potentiation of synaptic transmission only occurred in P1 and not in P2. This result reveals that the input specificity of LTP is only induced by the strong stimulation in P1.To test the associativity, we first applied a weak stimulus to the P2 pathway (protocol 3), and found that neither P1 nor P2 synapses showed changes in EPSP and EPSC amplitudes Figures . Next, w2+, AMPA conductance, and EPSC and EPSP amplitudes after stimulus  led to the elevated AMPA channel maximal conductance in P1  and BDNF mRNA (mBDNF) are adjustable parameters.In Equations , the postsynaptic CaCpost and mBDNF, we considered mBDNF = 0.1681 μM as the level prior to the stimulus, and varied Cpost. We induced a 2-s increase in Cpost from 0.004 mM to 0.02 mM, [BDNF] transited from a low to a high state and then remained in the high level state even when Cpost returned to its basal level, demonstrating bistable responses  to the coexistence of two stable steady states (low and high-level [BDNF]) along with an unstable state via a fold bifurcation (LP1), and further to only one stable steady state (high-level [BDNF]) via another fold bifurcation (LP2)  could be divided into three regions by two fold bifurcation curves  Figure . We perfs Figure ; bistabie Figure .Cpost, mBDNF) should lie in region I or II containing a low-level state such that the cleft BDNF concentration at the synapse [BDNF] is low prior to stimulation. Secondly, the synaptic stimulation prompts  to enter region III at only a high state, and then [BDNF] switches from low to high. Thirdly, after stimulation,  may remain in region III or II to maintain the high level [BDNF].The premise of the realization of LTP at the stimulated synapse is that the cleft BDNF at the synapse can arrive at a high level after stimulation. Therefore, we predicted that to achieve the induction of LTP at a synapse, three steps had to be fulfilled as follows. Firstly,  was different among synapses, while the BDNF mRNA level (mBDNF) was global and had the same value for all synapses.During the induction of LTP, it is essential to induce long-term plasticity via a transient stimulus. In previous simulations, a strong pulse in s Figure . These rl Figure . Here, wCpost and mBDNF values for both synapses 1 and 21 were the same and located at region I  reached region III at the end of the stimulation  returned to the low-level state at region I  reached the high-level state region III with a much higher level Cpost at the end of the stimulation  moved to and persisted at a high-level state at region III  showed little change, and  remained in the low state region I  increased to the high state at region III  reached the magenta dot immediately due to the increase in both Cpost and mBDNF. The increase in mBDNF originated from the induction of BDNF transcription through CREB, which was activated by the intracellular Ca2+ signal  persisted at the high-level state  could only trigger a brief increase in I Figure . Under p2+ and BDNF transcription in response to the stimulus. Hence, the proposed toy model is able to predict the behaviors of the whole system and supply guidance for the realization of LTP.The above findings revealed that the bistability of the local positive feedback motif of BDNF production could provide a unified mechanism of the cooperativity, input specificity, and associativity of LTP based on the dynamics of postsynaptic CaIn the above simulations, we explored the long-term behaviors in the postsynaptic neuron after stimulation, including changes in molecular concentrations, AMPA channel conductance, and EPSC and EPSP amplitudes. Next, we focus on the postsynaptic neuron activity during stimulation and discuss the role of the pre- and postsynaptic components in the realization of LTP.T  rose due to the high-frequency synaptic transmission at synapse 1  only exhibited a subthreshold oscillation  only exhibited small changes  remained at a low level  and applied the protocol 2. Our simulation showed a threshold response with respect to changes in the number n1. LTP at synapse 1 could not be induced at synapse 1 when n1 ≤ 7 and was induced when n1≥8, as shown by the clear increase in the normalized amplitudes of both EPSP and AMPA-mediated EPSC  with another event  . Hence, as a model of synapse dynamics, modifications of the proposed model with further details of STP could be capable of dealing with both the induction and maintenance of synaptic plasticity. In our model, to achieve long-term potentiation of the synaptic transmission, we introduced a positive feedback loop in each synapse that produces bistability. However, after the induction of LTP, the synaptic efficacy might not return to the low state if it remains in the high state for a long time, which is not completely in agreement with the experiments. To return to the low state, one might consider some other biological processes, such as degeneration of neurons, random inactivation of gene expressions, or changes in epigenetic states, etc. With the accumulation of experimental results concerning complex reactions that are localized to the postsynaptic density, it is feasible to add these details to the model. For future studies, computational models that involve multiple-level processes, including neural circuits, synapses and more detailed biochemical reactions, are required to facilitate the establishment of a more complete model to understand the synaptic plasticity and facilitate learning and memory.LH, ZY, and JL designed and performed the research and wrote the article.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.