The aromatic compounds,including o-xylene,m-xylene,p-xylene,and ethylbenzene,primarily originate from the catalytic reforming of crude oil,and have a wide variety of applications.However,because of similar physical an...The aromatic compounds,including o-xylene,m-xylene,p-xylene,and ethylbenzene,primarily originate from the catalytic reforming of crude oil,and have a wide variety of applications.However,because of similar physical and chemical properties,these compounds are difficult to be identified by gas chromatography(GC)without standard samples.With the development of modern nuclear magnetic resonance(NMR)techniques,NMR has emerged as a powerful and efficient tool for the rapid analysis of complex and crude mixtures without purification.In this study,the parameters of one-dimensional(1D)total correlation spectroscopy(TOCSY)NMR techniques,including 1D selective gradient TOCSY and 1D chemicalshift-selective filtration(CSSF)with TOCSY,were optimized to obtain comprehensive molecular structure information.The results indicate that the overlapped signals in NMR spectra of nonpolar aromatic compounds(including o-xylene,m-xylene,p-xylene and ethylbenzene),polar aromatic compounds(benzyl alcohol,benzaldehyde,benzoic acid),and aromatic compounds with additional conjugated bonds(styrene)can be resolved in 1D TOCSY.More importantly,full molecular structures can be clearly distinguished by setting appropriate mixing time in 1D TOCSY.This approach simplifies the NMR spectra,provides structural information of entire molecules,and can be applied for the analysis of other structural isomers.展开更多
Reference materials for quantitative determination of regulated heavy metals, such as Pb and Cd in electronic components, were designed and investigated in terms of stability and homogeneity. Reference materials with ...Reference materials for quantitative determination of regulated heavy metals, such as Pb and Cd in electronic components, were designed and investigated in terms of stability and homogeneity. Reference materials with two concentration levels of heavy metals were prepared by spiking Pb and Cd compounds to epoxy molding compounds made by mixing silica powders and epoxy resin. The concentration changes of the reference materials during stability test for 1 a were not observed. In the homogeneity assessment, the as-prepared reference materials were studied by using three different analytical tools, inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray fluoroescence spectrometry (XRF) and laser ablation ICP mass. The results show different homogeneities by the characteristics of analytical tools and the materials.展开更多
Compound Shenhua Tablet,a medicine comprising seven herbs,is employed in treating IgA nephropathy.This study aimed to meticulously analyze its chemical composition.Based on a list of candidate compounds,identified thr...Compound Shenhua Tablet,a medicine comprising seven herbs,is employed in treating IgA nephropathy.This study aimed to meticulously analyze its chemical composition.Based on a list of candidate compounds,identified through extensive literature review pertinent to the tablet’s herbal components,the composition analysis entailed the systematic identification,characterization,and quantification of the constituents.The analyte-capacity of LC/ESI-MS-based and GC/EI-MS-based assays was evaluated.The identified and characterized constituents were quantified to determine their content levels and were ranked based on the constituents’daily doses.A total of 283 constituents,classified into 12 distinct categories,were identified and characterized in the Compound Shenhua Tablet.These constituents exhibited content levels of 1−10982μg·g^(−1),with daily doses of 0.01−395μmol·d^(−1).The predominant constituents,with daily doses of≥10μmol·d^(−1),include nine organic acids(citric acid,quinic acid,chlorogenic acid,cryptochlorogenic acid,gallic acid,neochlorogenic acid,isochlorogenic acid C,isochlorogenic acid B,and linoleic acid),five iridoids(specnuezhenide,nuezhenoside G13,nuezhenidic acid,secoxyloganin,and secologanoside),two monoterpene glycosides(paeoniflorin and albiflorin),a sesquiterpenoid(curzerenone),a triterpenoid(oleanolic acid),and a phenylethanoid(salidroside).Additionally,there were 83,126,and 55 constituents detected in the medicine with daily doses of 1–10,0.1–1,and 0.01–0.1μmol·d^(−1),respectively.The combination of the LC/ESI-MS-based and GC/EI-MS-based assays demonstrated a complementary relationship in their analyte-capacity for detecting the constituents present in the medicine.This comprehensive composition analysis establishes a solid foundation for further pharmacological research on Compound Shenhua Tablet and facilitates the quality evaluation of this complex herbal medicine.展开更多
The associations of volatile organic compounds(VOCs)exposure with short sleep duration(SSD)have rarely been studied.We aimed to evaluate the correlation between VOC exposure and SSD risk,while also exploring the poten...The associations of volatile organic compounds(VOCs)exposure with short sleep duration(SSD)have rarely been studied.We aimed to evaluate the correlation between VOC exposure and SSD risk,while also exploring the potential mediating influence of depressive symptoms.Blood concentrations of seven VOCs,namely benzene,toluene,ethylbenzene,m-/p-xylene,o-xylene,styrene(collectively known as BTEXS),and 1,4-dichlorobenzene,were analyzed in 2905 U.S.adults.Weighted logistic regression,quantile-based g-computation(QGC),and weighted quantile sum(WQS)regression were employed to investigate associations between selected VOCs and SSD risk.Mediation analyses were conducted to explore the potential mediating effects of depressive symptoms on these relationships.Increased blood levels of BTEXS were positively correlated with SSD risk,with odds ratios(OR)ranging from 1.130 to 1.212(all P<0.05).A nonlinear association between toluene concentration and SSD risk was observed(P for nonlinearity=0.028).Both QGC and WQS analyses indicated a positive association between co-exposure to VOCs and SSD,with styrene showing the highest positive weights(QGC:OR=1.313,95%confidence interval(CI):1.038–1.660;WQS:OR=1.386,95%CI:1.111–1.731).Furthermore,BTEXS exposure was positively linked to depressive symptoms,which in turn were significantly associated with SSD risk.Mediation analyses revealed that depressive symptoms partially mediated the relationships between individual and mixed VOCs and SSD risk,with mediation proportions ranging from 15.87%to 20.54%(all P<0.05).These findings indicated that exposure to VOCs increased SSD risk,with depressive symptoms playing a partial mediating role.展开更多
This study explores the relationship between cardiac activity and biochemical indicators in Pacific oysters(Crassostrea gigas)during cold storage to develop a nondestructive vitality assessment method.Oysters were sto...This study explores the relationship between cardiac activity and biochemical indicators in Pacific oysters(Crassostrea gigas)during cold storage to develop a nondestructive vitality assessment method.Oysters were stored at−1℃ for 14 d,with cardiac patterns tracked via image analysis,and biochemical markers(pH,adenosine triphosphate(ATP)-related compounds,and adenylate energy charge(AEC))were assessed.Five cardiac patterns were identified,with regular alternating contractions common early but decreasing over time,aligning with declines in AEC(44.11%-35.52%)and pH(6.98-6.55).The intervals between ventricular and atrial contractions rose from 4.2 to 5.6 s,strongly correlating with biochemical signs of vitality loss.Image analysis revealed characteristic waveforms for each cardiac pattern,despite amplitude variations caused by optical artifacts.These findings indicate that cardiac pattern analysis via image processing could be an effective nondestructive indicator of oyster vitality,offering a novel approach to quality control in shellfish storage and distribution.展开更多
Lemon oils are broadly used as flavoring agents in beverages,foods,cosmetics and pharmaceuticals,yet the adulteration of natural,particularly cold pressed lemon oils is very common in the industry due to its unmet dem...Lemon oils are broadly used as flavoring agents in beverages,foods,cosmetics and pharmaceuticals,yet the adulteration of natural,particularly cold pressed lemon oils is very common in the industry due to its unmet demand and high cost.Nowadays,most quality control(QC)analysis of lemon oils is conducted by gas chromatography(GC)analysis,which is far from a reliable method.Oxygen heterocyclic compounds(OHCs)in non-volatile fraction are gaining increasing attention in authentication process because of the nearly finger-printing profiles of OHCs in cold pressed citrus essential oils.Our goal in this study was to identify OHCs using high performance liquid chromatography(HPLC)in lemon oils,establish OHC profiles,perform stepwise logistic regression analysis(SLRA)and build effective predicting model and further determine adulterated lemon oils by referencing the OHC profiles and established models.After HPLC analyses,profiling and SLRA modeling of 154 OHCs samples of industrial lemon oils,we found that the combination of isopimpinellin and total OHC concentration are essential and robust predictors to differentiate authentic samples from adulterated lemon oils with a success rate of 98%from the 5-fold cross validation.This study provided a reliable and efficient method in determining the authenticity of lemon oils.展开更多
AIM: To study liver cell apoptosis caused by the toxicity of selenium and observe the alteration of choline compounds using in vitro 9.4T high resolution magnetic resonance spectroscopy. METHODS: Twenty male Wistar ra...AIM: To study liver cell apoptosis caused by the toxicity of selenium and observe the alteration of choline compounds using in vitro 9.4T high resolution magnetic resonance spectroscopy. METHODS: Twenty male Wistar rats were randomly divided into two groups. The rats in the treatment group were intraperitoneally injected with sodium selenite and the control group with distilled water. All rats were sacrifi ced and the livers were dissected. 1H-MRS data were collected using in vitro 9.4T high resolution magnetic resonance spectrometer. Spectra were processed using XWINNMR and MestRe-c 4.3. HE and TUNEL staining was employed to detect and confi rm the change of liver cells. RESULTS: Good 1H-MR spectra of perchloric acid extract from liver tissue of rats were obtained. The conventional metabolites were detected and assigned. Concentrations of different ingredient choline compounds in treatment group vs control group were as follows: total choline compounds,5.08 ± 0.97 mmol/L vs 3.81 ± 1.16 mmol/L (P = 0.05); and free choline,1.07 ± 0.23 mmol/L vs 0.65 ± 0.20 mmol/L (P = 0.00). However,there was no statistical signif icance between the two groups. The hepatic sinus and cellular structure of hepatic cells in treatmentgroup were abnormal. Apoptosis of hepatic cells was confi rmed by TUNEL assay. CONCLUSION: High dose selenium compounds can cause the rat liver lesion and induce cell apoptosis in vivo. High resolution 1H-MRS in vitro can detect diversified metabolism. The changing trend for different ingredient of choline compounds is not completely the same at early period of apoptosis.展开更多
The present study investigated quantitatively the significance of HNLC (high-nutrient low-chlorophyll) regions and its grazing control with the improved iron fertilization for climate change. The limitation of iron (F...The present study investigated quantitatively the significance of HNLC (high-nutrient low-chlorophyll) regions and its grazing control with the improved iron fertilization for climate change. The limitation of iron (Fe) for phytoplankton growth in HNLC regions was confirmed by sulfur compounds (S) such as volcanic ash and hydrogen sulfide (H2S) in batch cultures, whose chemical sediment of Fe3S4 showed 4.06 wt%. The technologies developed for iron fertilization since 1993 till now were not practical to provide sufficient amounts of bioavailable iron due to sedimentary iron sulfides induced by undersea volcanic sulfur compounds. The proposed technology for iron fertilization was improved to enhance the bioavailable iron to phytoplankton by keeping minimal sulfur compounds in HNLC regions. The low productivity of phytoplankton by grazing control in HNLC regions was 6% diatoms whose 52% was grazed by copepods and 42% by krill on the basis of data analysis in 2000 EisenEx Experiment at boundary of Antarctic and African tectonic plates. All of the previous iron fertilization experiments were conducted at volcanic sulfur compounds enriched HNLC regions. The present study revealed that the enhanced phytoplankton productivity in batch culture without sedimentary iron sulfides can be possible only if sulfur compounds are minimal, as is in Shag Rocks (53°S, 42°W) of South Georgia in Scotia Sea in the Southern Ocean.展开更多
In order to analyze the complex chemical kinetic mechanism systematically and find out the redundant species and reactions, a numerical platform for mechanism analysis and simplification is established basing on Path ...In order to analyze the complex chemical kinetic mechanism systematically and find out the redundant species and reactions, a numerical platform for mechanism analysis and simplification is established basing on Path Flux Analysis （PFA）. It is used to reduce a detailed mechanism for flame inhibited by phosphorus containing compounds, a reduced mechanism with 65 species and 335 reactions is obtained. The detailed and reduced mechanism are both used to calculate the freely-propagating premix C3H8/air flame with different dimethyl methylphosphonate doped over a wide range of equivalence ratios. The concentration distributions of free radicals and major species are compared, and the results under two different mechanisms agree well. The laminar flame speed obtained by the two mechanisms also matches well, with the maximum relative error introduces as a small value of 1.7%. On the basis of the reduced mechanism validation, the correlativity analysis is conducted between flame speed and flee radical concentrations, which can provide information for target species selection in the further mechanism reduction. By analyzing the species and reactions fluxes, the species and reaction paths which contribute the flame inhibition significantly are determined.展开更多
Factor analysis is used to study the organic compounds that have high degree of correlation with biomass in algal blooming. Based on this correlation, they are named characteristic organic compounds. The compounds fou...Factor analysis is used to study the organic compounds that have high degree of correlation with biomass in algal blooming. Based on this correlation, they are named characteristic organic compounds. The compounds found are sequalene (SQU), cedrol (CED), 2, 5-cyclohexadiene-1, 4-dione, 2, 6-bis(1, 1-dimthylethyl ) (PBQ), phenol, 2, 6-bis (1, 1-dimethylethy-4-methyl) (BHT), 3-t-butyl-4- hydroxyanisole ( BHA ), 1, 2-benzenedicarboxylie acid, bis-( 2-methyl propyl ) ester (DIBP), dibutyl phthalate (DNBP), respectively. Monitoring the variations of concentration of these characteristic organic compounds in seawater may provide scientific basis for studying and forecasting red tides.展开更多
Pathogenic microorganisms produce numerous metabolites,including volatile organic compounds(VOCs).Monitoring these metabolites in biological matrices(e.g.,urine,blood,or breath)can reveal the presence of specific micr...Pathogenic microorganisms produce numerous metabolites,including volatile organic compounds(VOCs).Monitoring these metabolites in biological matrices(e.g.,urine,blood,or breath)can reveal the presence of specific microorganisms,enabling the early diagnosis of infections and the timely implementation of tar-geted therapy.However,complex matrices only contain trace levels of VOCs,and their constituent com-ponents can hinder determination of these compounds.Therefore,modern analytical techniques enabling the non-invasive identification and precise quantification of microbial VOCs are needed.In this paper,we discuss bacterial VOC analysis under in vitro conditions,in animal models and disease diagnosis in humans,including techniques for offline and online analysis in clinical settings.We also consider the advantages and limitations of novel microextraction techniques used to prepare biological samples for VOC analysis,in addition to reviewing current clinical studies on bacterial volatilomes that address inter-species in-teractions,the kinetics of VOC metabolism,and species-and drug-resistance specificity.展开更多
As the important matrix material,epoxy resin has been widely used in the composites for various fields.On account of the poor toughness of epoxy resin limiting their suitability for advanced applications,considerable ...As the important matrix material,epoxy resin has been widely used in the composites for various fields.On account of the poor toughness of epoxy resin limiting their suitability for advanced applications,considerable interests have been conducted to modify the epoxy resin to meet the engineering requirements.In this study,the bio-based polyurethane(PU)modified resin was adopted to modify the pure bisphenol-A epoxy by blending method with various proportions.Aiming to illuminate the curing behavior,mechanical and thermal properties,the blended epoxy systems were characterized by viscosity-time analysis,dynamic mechanical analysis(DMA)at different frequencies and temperatures,mechanical tensile test,thermogravimetric analysis(TGA)and Fourier transform infrared(FT-IR)spectroscopy.The results indicated that the introduction of PU modified epoxy was found to significantly inhibit the viscosity growth rates especially when the content of PU modified epoxy resin is higher than 60%.Notwithstanding the dynamic modulus and T_(g)reduced with the increment of PU modified epoxy,remarkable increment on the elongation at break was found and the flexibility was greatly promoted with the introduction of PU modified epoxy.The proportion of PU modified epoxy in the blends should be put balance considerations to obtain optimal mechanical properties.TGA results and FTIR spectrum demonstrated that the addition of PU modified epoxy did not change the thermal decomposition mechanism and chemical reaction mechanism,but the addition of PU modified epoxy inhibits the curing reaction of epoxy resin by measured and calculated the damping temperature domainT from 35.7℃ to 48.9℃.展开更多
Low-basis-weight paper lacks normal strength and stiffness. Waterborne epoxy resin could be employed with oxidized starch to improve paper stiffness through surface sizing. In this study,the mechanism of enhancing sti...Low-basis-weight paper lacks normal strength and stiffness. Waterborne epoxy resin could be employed with oxidized starch to improve paper stiffness through surface sizing. In this study,the mechanism of enhancing stiffness by adding waterborne epoxy resin was fully investigated. The results indicated that through surface sizing with epoxy resin,the paper thickness was preserved,whereas the elastic modulus increased significantly and the epoxy resin had positive impact on single fiber strength. A rigid resin layer and interpenetrating polymer network formed on the surface and in the inner layer of the paper,respectively. The formed resin layer and interpenetrating polymer network strongly supported the paper,leading to the improvement of the elastic modulus and stiffness. The stiffness improvement through surface sizing was mainly due to the formation of a fibrous composite layer and penetration of the sizing agent into the inner layers of the paper. The better the combination between fiber and sizing agent,the higher were the elastic modulus and the stiffness of the whole paper.展开更多
In this paper, an efficient thermal analysis method is presented for large scale compound semiconductor integrated circuits based on a heterojunction bipolar transistor with considering the change of thermal conductiv...In this paper, an efficient thermal analysis method is presented for large scale compound semiconductor integrated circuits based on a heterojunction bipolar transistor with considering the change of thermal conductivity with temperature.The influence caused by the thermal conductivity can be equivalent to the increment of the local temperature surrounding the individual device. The junction temperature for each device can be efficiently calculated by the combination of the semianalytic temperature distribution function and the iteration of local temperature with high accuracy, providing a temperature distribution for a full chip. Applying this method to the InP frequency divider chip and the GaAs analog to digital converter chip, the computational results well agree with the results from the simulator COMSOL and the infrared thermal imager respectively. The proposed method can also be applied to thermal analysis in various kinds of semiconductor integrated circuits.展开更多
Sentiment analysis is a fine‐grained analysis task that aims to identify the sentiment polarity of a specified sentence.Existing methods in Chinese sentiment analysis tasks only consider sentiment features from a sin...Sentiment analysis is a fine‐grained analysis task that aims to identify the sentiment polarity of a specified sentence.Existing methods in Chinese sentiment analysis tasks only consider sentiment features from a single pole and scale and thus cannot fully exploit and utilise sentiment feature information,making their performance less than ideal.To resolve the problem,the authors propose a new method,GP‐FMLNet,that integrates both glyph and phonetic information and design a novel feature matrix learning process for phonetic features with which to model words that have the same pinyin information but different glyph information.Our method solves the problem of misspelling words influencing sentiment polarity prediction results.Specifically,the authors iteratively mine character,glyph,and pinyin features from the input comments sentences.Then,the authors use soft attention and matrix compound modules to model the phonetic features,which empowers their model to keep on zeroing in on the dynamic‐setting words in various positions and to dispense with the impacts of the deceptive‐setting ones.Ex-periments on six public datasets prove that the proposed model fully utilises the glyph and phonetic information and improves on the performance of existing Chinese senti-ment analysis algorithms.展开更多
Mushrooms are well-known to possess a continuum of anticancer metabolites that are vital in the development of anticancer adjuvant drug leads based on natural products. Owing to the fact that conventional cancer thera...Mushrooms are well-known to possess a continuum of anticancer metabolites that are vital in the development of anticancer adjuvant drug leads based on natural products. Owing to the fact that conventional cancer therapeutic methods were failed to lessen mortality caused by cancer to the estimated level with occurrence of adverse side effects, anticancer agents isolated from natural mushroom sources unarguably make an experimental research area worth mass focus today. The current study was targeted on in vitro cytotoxicity and in silico predictive pharmacological analysis of a flavonoid compound isolated from Fulvifomes fastuosus mushroom. Targeted compound was isolated from the mushroom using different chromatographic methods and identified by NMR spectrometry and mass spectrometry. Cytotoxicity experiments were carried out using MTT assay and apoptotic cells were identified by ethidium bromide/acridine orange staining. The SwissADME tool, BOILED-Egg construction model and Swiss target protein prediction software have been used to perform in silico predictive pharmacological analysis. The isolated compound has been identified as 2-(3,4-dihydroxyphenyl)-6-[(E)-2-(3,4-dihydroxyphenyl)ethenyl]-5'-methylspiro[2H-furo[3,2-c]pyran-3,2'-furan]-3',4-dione by spectrometric methods. The result of MTT assay showed that 2-(3,4-dihydroxyphenyl)-6-[(E)-2-(3,4-dihydroxyphenyl)ethenyl]-5'-methylspiro[2H-furo[3,2-c]pyran-3,2'-furan]-3',4-dione has potent anticancer activity for hepatoma against Hep-G2 cell line (IC50 = 20.8 μg/ml) being less toxic to normal CC-1 epithelial cells (IC50 = 167.00 μM). The cells treated with compound ex-hibited apoptotic features such as cellular shrinkage, nuclear fragmentation and condensed cytoplasm. In summary, 2-(3,4-dihydroxyphenyl)-6-[(E)-2-(3,4-dihydroxyphenyl)ethenyl]-5'-methylspiro[2H-furo[3,2-c]pyran-3,2'-furan]-3',4-dione has shown potent anticancer properties against hepatoma with less cytotoxicity effect on normal cells. Furthermore, in silico study has revealed that properties of 2-(3,4-dihydroxyphenyl)-6-[(E)-2-(3,4-dihydroxyphenyl)ethenyl]-5'-methylspiro[2H-furo[3,2-c]pyran-3,2'-furan]-3',4-dione may contribute to making a high absorption and clearance of the test compound as not interfering with the therapeutic failure of the compound. The properties of 2-(3,4-dihydroxyphenyl)-6-[(E)-2-(3,4-dihydroxyphenyl)ethenyl]-5'-methylspiro[2H-furo-[3,2-c]pyran-3,2'-furan]-3',4-dione were compatible with well-known anticancer drug lapatinib. In conclusion, 2-(3,4-dihydroxyphenyl)-6-[(E)-2-(3,4-dihydroxyphenyl)ethenyl]-5'-methylspiro[2H-furo[3,2-c]pyran-3,2'-furan]-3',4-dione has a high tendency to act as a good anticancer adjuvant drug in the treatment of hepatoma.展开更多
BACKGROUND Colonization with Helicobacter pylori(H.pylori)has a strong correlation with gastric cancer,and the virulence factor CagA is implicated in carcinogenesis.Studies have been conducted using medicinal plants w...BACKGROUND Colonization with Helicobacter pylori(H.pylori)has a strong correlation with gastric cancer,and the virulence factor CagA is implicated in carcinogenesis.Studies have been conducted using medicinal plants with the aim of eliminating the pathogen;however,the possibility of blocking H.pylori-induced cell differentiation to prevent the onset and/or progression of tumors has not been addressed.This type of study is expensive and time-consuming,requiring in vitro and/or in vivo tests,which can be solved using bioinformatics.Therefore,prospective computational analyses were conducted to assess the feasibility of interaction between phenolic compounds from medicinal plants and the CagA oncoprotein.AIM To perform a computational prospecting of the interactions between phenolic compounds from medicinal plants and the CagA oncoprotein of H.pylori.METHODS In this in silico study,the structures of the phenolic compounds(ligands)kaempferol,myricetin,quercetin,ponciretin(flavonoids),and chlorogenic acid(phenolic acid)were selected from the PubChem database.These phenolic compounds were chosen based on previous studies that suggested medicinal plants as non-drug treatments to eliminate H.pylori infection.The three-dimensional structure model of the CagA oncoprotein of H.pylori(receptor)was obtained through molecular modeling using computational tools from the I-Tasser platform,employing the threading methodology.The primary sequence of CagA was sourced from GenBank(BAK52797.1).A screening was conducted to identify binding sites in the structure of the CagA oncoprotein that could potentially interact with the ligands,utilizing the GRaSP online platform.Both the ligands and receptor were prepared for molecular docking using AutoDock Tools 4(ADT)software,and the simulations were carried out using a combination of ADT and AutoDock Vina v.1.2.0 software.Two sets of simulations were performed:One involving the central region of CagA with phenolic compounds,and another involving the carboxy-terminus region of CagA with phenolic compounds.The receptor-ligand complexes were then analyzed using PyMol and BIOVIA Discovery Studio software.RESULTS The structure model obtained for the CagA oncoprotein exhibited high quality(C-score=0.09)and was validated using parameters from the MolProbity platform.The GRaSP online platform identified 24 residues(phenylalanine and leucine)as potential binding sites on the CagA oncoprotein.Molecular docking simulations were conducted with the three-dimensional model of the CagA oncoprotein.No complexes were observed in the simulations between the carboxy-terminus region of CagA and the phenolic compounds;however,all phenolic compounds interacted with the central region of the oncoprotein.Phenolic compounds and CagA exhibited significant affinity energy(-7.9 to-9.1 kcal/mol):CagA/kaempferol formed 28 chemical bonds,CagA/myricetin formed 18 chemical bonds,CagA/quercetin formed 16 chemical bonds,CagA/ponciretin formed 13 chemical bonds,and CagA/chlorogenic acid formed 17 chemical bonds.Although none of the phenolic compounds directly bound to the amino acid residues of the K-Xn-R-X-R membrane binding motif,all of them bound to residues,mostly positively or negatively charged,located near this region.CONCLUSION In silico,the tested phenolic compounds formed stable complexes with CagA.Therefore,they could be tested in vitro and/or in vivo to validate the findings,and to assess interference in CagA/cellular target interactions and in the oncogenic differentiation of gastric cells.展开更多
The content of berberine hydrochloride(BH)in compound berberine tablets(CBTs)is subject to strict requirements.Its content is usually measured based on chemical analysis.In this paper,the fluorescence spectral imaging...The content of berberine hydrochloride(BH)in compound berberine tablets(CBTs)is subject to strict requirements.Its content is usually measured based on chemical analysis.In this paper,the fluorescence spectral imaging method was used to study the relative content of BH from a physics perspective.By comparing the relative fluorescence intensity of self-made CBTs with di®erent mass percentages of BH,a linear positive relationship was observed between the BH content and the relative fluorescence intensity,and accordingly the quality of CBTs of different brands was evaluated.The results indicate that the fluorescence spectral imaging method can be a simple,fast and nondestructive semi-quantitative analysis method to determine the content of BH in CBTs,and this method has great potential in the quality control of CBTs.展开更多
An epoxy penetration technique was used to reproduce and analyze the pitting corrosion process occurred at a steel coupon surface. The samples were exposed to the resin under high vacuum conditions, in order to fulfil...An epoxy penetration technique was used to reproduce and analyze the pitting corrosion process occurred at a steel coupon surface. The samples were exposed to the resin under high vacuum conditions, in order to fulfill the pits caused by the corrosion process. With this technique, a 3D image of the corrosion damages was obtained. Once the image of the damaged surface was obtained, a Scanning Electron Microscope (SEM) was used to analyze the morphology of the pits exhibited by the steel sample. The results were satisfactory, as different parameters such as the diameter, shape and depth of the pits originated, along with the corrosion preferential path, could be established. According to the results, the use of the epoxy penetration technique may be considered as alternating pitting corrosion analysis technique.展开更多
基金We thank the Natural Science Foundation of Shanxi Province(202103021224439)National Natural Science Foundation of China(22075308)for financial support.
文摘The aromatic compounds,including o-xylene,m-xylene,p-xylene,and ethylbenzene,primarily originate from the catalytic reforming of crude oil,and have a wide variety of applications.However,because of similar physical and chemical properties,these compounds are difficult to be identified by gas chromatography(GC)without standard samples.With the development of modern nuclear magnetic resonance(NMR)techniques,NMR has emerged as a powerful and efficient tool for the rapid analysis of complex and crude mixtures without purification.In this study,the parameters of one-dimensional(1D)total correlation spectroscopy(TOCSY)NMR techniques,including 1D selective gradient TOCSY and 1D chemicalshift-selective filtration(CSSF)with TOCSY,were optimized to obtain comprehensive molecular structure information.The results indicate that the overlapped signals in NMR spectra of nonpolar aromatic compounds(including o-xylene,m-xylene,p-xylene and ethylbenzene),polar aromatic compounds(benzyl alcohol,benzaldehyde,benzoic acid),and aromatic compounds with additional conjugated bonds(styrene)can be resolved in 1D TOCSY.More importantly,full molecular structures can be clearly distinguished by setting appropriate mixing time in 1D TOCSY.This approach simplifies the NMR spectra,provides structural information of entire molecules,and can be applied for the analysis of other structural isomers.
基金Project(2010-0008-276) supported by NCRC (National Core Research Center) program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology
文摘Reference materials for quantitative determination of regulated heavy metals, such as Pb and Cd in electronic components, were designed and investigated in terms of stability and homogeneity. Reference materials with two concentration levels of heavy metals were prepared by spiking Pb and Cd compounds to epoxy molding compounds made by mixing silica powders and epoxy resin. The concentration changes of the reference materials during stability test for 1 a were not observed. In the homogeneity assessment, the as-prepared reference materials were studied by using three different analytical tools, inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray fluoroescence spectrometry (XRF) and laser ablation ICP mass. The results show different homogeneities by the characteristics of analytical tools and the materials.
基金supported by the National Natural Science Foundation of China(Nos.82192912,82074273)the Innovation Team and Talents Cultivation Program of National Administration of Traditional Chinese Medicine(No.ZYYCXTD-C-202009)the Program of State Key Laboratory of Drug Research(No.SIMM2103ZZ-06).
文摘Compound Shenhua Tablet,a medicine comprising seven herbs,is employed in treating IgA nephropathy.This study aimed to meticulously analyze its chemical composition.Based on a list of candidate compounds,identified through extensive literature review pertinent to the tablet’s herbal components,the composition analysis entailed the systematic identification,characterization,and quantification of the constituents.The analyte-capacity of LC/ESI-MS-based and GC/EI-MS-based assays was evaluated.The identified and characterized constituents were quantified to determine their content levels and were ranked based on the constituents’daily doses.A total of 283 constituents,classified into 12 distinct categories,were identified and characterized in the Compound Shenhua Tablet.These constituents exhibited content levels of 1−10982μg·g^(−1),with daily doses of 0.01−395μmol·d^(−1).The predominant constituents,with daily doses of≥10μmol·d^(−1),include nine organic acids(citric acid,quinic acid,chlorogenic acid,cryptochlorogenic acid,gallic acid,neochlorogenic acid,isochlorogenic acid C,isochlorogenic acid B,and linoleic acid),five iridoids(specnuezhenide,nuezhenoside G13,nuezhenidic acid,secoxyloganin,and secologanoside),two monoterpene glycosides(paeoniflorin and albiflorin),a sesquiterpenoid(curzerenone),a triterpenoid(oleanolic acid),and a phenylethanoid(salidroside).Additionally,there were 83,126,and 55 constituents detected in the medicine with daily doses of 1–10,0.1–1,and 0.01–0.1μmol·d^(−1),respectively.The combination of the LC/ESI-MS-based and GC/EI-MS-based assays demonstrated a complementary relationship in their analyte-capacity for detecting the constituents present in the medicine.This comprehensive composition analysis establishes a solid foundation for further pharmacological research on Compound Shenhua Tablet and facilitates the quality evaluation of this complex herbal medicine.
文摘The associations of volatile organic compounds(VOCs)exposure with short sleep duration(SSD)have rarely been studied.We aimed to evaluate the correlation between VOC exposure and SSD risk,while also exploring the potential mediating influence of depressive symptoms.Blood concentrations of seven VOCs,namely benzene,toluene,ethylbenzene,m-/p-xylene,o-xylene,styrene(collectively known as BTEXS),and 1,4-dichlorobenzene,were analyzed in 2905 U.S.adults.Weighted logistic regression,quantile-based g-computation(QGC),and weighted quantile sum(WQS)regression were employed to investigate associations between selected VOCs and SSD risk.Mediation analyses were conducted to explore the potential mediating effects of depressive symptoms on these relationships.Increased blood levels of BTEXS were positively correlated with SSD risk,with odds ratios(OR)ranging from 1.130 to 1.212(all P<0.05).A nonlinear association between toluene concentration and SSD risk was observed(P for nonlinearity=0.028).Both QGC and WQS analyses indicated a positive association between co-exposure to VOCs and SSD,with styrene showing the highest positive weights(QGC:OR=1.313,95%confidence interval(CI):1.038–1.660;WQS:OR=1.386,95%CI:1.111–1.731).Furthermore,BTEXS exposure was positively linked to depressive symptoms,which in turn were significantly associated with SSD risk.Mediation analyses revealed that depressive symptoms partially mediated the relationships between individual and mixed VOCs and SSD risk,with mediation proportions ranging from 15.87%to 20.54%(all P<0.05).These findings indicated that exposure to VOCs increased SSD risk,with depressive symptoms playing a partial mediating role.
基金supported by the Japan Society for the Promotion of Science(No.19H05611).
文摘This study explores the relationship between cardiac activity and biochemical indicators in Pacific oysters(Crassostrea gigas)during cold storage to develop a nondestructive vitality assessment method.Oysters were stored at−1℃ for 14 d,with cardiac patterns tracked via image analysis,and biochemical markers(pH,adenosine triphosphate(ATP)-related compounds,and adenylate energy charge(AEC))were assessed.Five cardiac patterns were identified,with regular alternating contractions common early but decreasing over time,aligning with declines in AEC(44.11%-35.52%)and pH(6.98-6.55).The intervals between ventricular and atrial contractions rose from 4.2 to 5.6 s,strongly correlating with biochemical signs of vitality loss.Image analysis revealed characteristic waveforms for each cardiac pattern,despite amplitude variations caused by optical artifacts.These findings indicate that cardiac pattern analysis via image processing could be an effective nondestructive indicator of oyster vitality,offering a novel approach to quality control in shellfish storage and distribution.
文摘Lemon oils are broadly used as flavoring agents in beverages,foods,cosmetics and pharmaceuticals,yet the adulteration of natural,particularly cold pressed lemon oils is very common in the industry due to its unmet demand and high cost.Nowadays,most quality control(QC)analysis of lemon oils is conducted by gas chromatography(GC)analysis,which is far from a reliable method.Oxygen heterocyclic compounds(OHCs)in non-volatile fraction are gaining increasing attention in authentication process because of the nearly finger-printing profiles of OHCs in cold pressed citrus essential oils.Our goal in this study was to identify OHCs using high performance liquid chromatography(HPLC)in lemon oils,establish OHC profiles,perform stepwise logistic regression analysis(SLRA)and build effective predicting model and further determine adulterated lemon oils by referencing the OHC profiles and established models.After HPLC analyses,profiling and SLRA modeling of 154 OHCs samples of industrial lemon oils,we found that the combination of isopimpinellin and total OHC concentration are essential and robust predictors to differentiate authentic samples from adulterated lemon oils with a success rate of 98%from the 5-fold cross validation.This study provided a reliable and efficient method in determining the authenticity of lemon oils.
基金The National Natural Science Foundation of China,No.30570480
文摘AIM: To study liver cell apoptosis caused by the toxicity of selenium and observe the alteration of choline compounds using in vitro 9.4T high resolution magnetic resonance spectroscopy. METHODS: Twenty male Wistar rats were randomly divided into two groups. The rats in the treatment group were intraperitoneally injected with sodium selenite and the control group with distilled water. All rats were sacrifi ced and the livers were dissected. 1H-MRS data were collected using in vitro 9.4T high resolution magnetic resonance spectrometer. Spectra were processed using XWINNMR and MestRe-c 4.3. HE and TUNEL staining was employed to detect and confi rm the change of liver cells. RESULTS: Good 1H-MR spectra of perchloric acid extract from liver tissue of rats were obtained. The conventional metabolites were detected and assigned. Concentrations of different ingredient choline compounds in treatment group vs control group were as follows: total choline compounds,5.08 ± 0.97 mmol/L vs 3.81 ± 1.16 mmol/L (P = 0.05); and free choline,1.07 ± 0.23 mmol/L vs 0.65 ± 0.20 mmol/L (P = 0.00). However,there was no statistical signif icance between the two groups. The hepatic sinus and cellular structure of hepatic cells in treatmentgroup were abnormal. Apoptosis of hepatic cells was confi rmed by TUNEL assay. CONCLUSION: High dose selenium compounds can cause the rat liver lesion and induce cell apoptosis in vivo. High resolution 1H-MRS in vitro can detect diversified metabolism. The changing trend for different ingredient of choline compounds is not completely the same at early period of apoptosis.
文摘The present study investigated quantitatively the significance of HNLC (high-nutrient low-chlorophyll) regions and its grazing control with the improved iron fertilization for climate change. The limitation of iron (Fe) for phytoplankton growth in HNLC regions was confirmed by sulfur compounds (S) such as volcanic ash and hydrogen sulfide (H2S) in batch cultures, whose chemical sediment of Fe3S4 showed 4.06 wt%. The technologies developed for iron fertilization since 1993 till now were not practical to provide sufficient amounts of bioavailable iron due to sedimentary iron sulfides induced by undersea volcanic sulfur compounds. The proposed technology for iron fertilization was improved to enhance the bioavailable iron to phytoplankton by keeping minimal sulfur compounds in HNLC regions. The low productivity of phytoplankton by grazing control in HNLC regions was 6% diatoms whose 52% was grazed by copepods and 42% by krill on the basis of data analysis in 2000 EisenEx Experiment at boundary of Antarctic and African tectonic plates. All of the previous iron fertilization experiments were conducted at volcanic sulfur compounds enriched HNLC regions. The present study revealed that the enhanced phytoplankton productivity in batch culture without sedimentary iron sulfides can be possible only if sulfur compounds are minimal, as is in Shag Rocks (53°S, 42°W) of South Georgia in Scotia Sea in the Southern Ocean.
基金Supported by the National Natural Science Foundation of China （51176181）, the National Basic Research Program of China （2012CB719704）, and the Research Fund for the Doctoral Program of Higher Education （20123402110047）.
文摘In order to analyze the complex chemical kinetic mechanism systematically and find out the redundant species and reactions, a numerical platform for mechanism analysis and simplification is established basing on Path Flux Analysis （PFA）. It is used to reduce a detailed mechanism for flame inhibited by phosphorus containing compounds, a reduced mechanism with 65 species and 335 reactions is obtained. The detailed and reduced mechanism are both used to calculate the freely-propagating premix C3H8/air flame with different dimethyl methylphosphonate doped over a wide range of equivalence ratios. The concentration distributions of free radicals and major species are compared, and the results under two different mechanisms agree well. The laminar flame speed obtained by the two mechanisms also matches well, with the maximum relative error introduces as a small value of 1.7%. On the basis of the reduced mechanism validation, the correlativity analysis is conducted between flame speed and flee radical concentrations, which can provide information for target species selection in the further mechanism reduction. By analyzing the species and reactions fluxes, the species and reaction paths which contribute the flame inhibition significantly are determined.
基金This work is supported by the National Natural Science Foundation of China (29977029).
文摘Factor analysis is used to study the organic compounds that have high degree of correlation with biomass in algal blooming. Based on this correlation, they are named characteristic organic compounds. The compounds found are sequalene (SQU), cedrol (CED), 2, 5-cyclohexadiene-1, 4-dione, 2, 6-bis(1, 1-dimthylethyl ) (PBQ), phenol, 2, 6-bis (1, 1-dimethylethy-4-methyl) (BHT), 3-t-butyl-4- hydroxyanisole ( BHA ), 1, 2-benzenedicarboxylie acid, bis-( 2-methyl propyl ) ester (DIBP), dibutyl phthalate (DNBP), respectively. Monitoring the variations of concentration of these characteristic organic compounds in seawater may provide scientific basis for studying and forecasting red tides.
基金funded by the National Science Centre,Poland(Project No.:2017/26/D/NZ6/00136).
文摘Pathogenic microorganisms produce numerous metabolites,including volatile organic compounds(VOCs).Monitoring these metabolites in biological matrices(e.g.,urine,blood,or breath)can reveal the presence of specific microorganisms,enabling the early diagnosis of infections and the timely implementation of tar-geted therapy.However,complex matrices only contain trace levels of VOCs,and their constituent com-ponents can hinder determination of these compounds.Therefore,modern analytical techniques enabling the non-invasive identification and precise quantification of microbial VOCs are needed.In this paper,we discuss bacterial VOC analysis under in vitro conditions,in animal models and disease diagnosis in humans,including techniques for offline and online analysis in clinical settings.We also consider the advantages and limitations of novel microextraction techniques used to prepare biological samples for VOC analysis,in addition to reviewing current clinical studies on bacterial volatilomes that address inter-species in-teractions,the kinetics of VOC metabolism,and species-and drug-resistance specificity.
基金The authors acknowledge the financial support of the National Natural Science Foundation of China(No.51908330)the Qilu Young Scholars Program of Shandong University,Natural Science Foundation of Shandong Province(CN)(No.ZR2020ME244),the Fundamental Research Funds of Shandong University(No.2020GN059)the Fundamental Research Funds for the Central Universities,CHD(No.300102210502)and Scientific Research Project of Shandong High-speed Group Co.,Ltd.,(No.SDGS-KJCX-2020-006-08).
文摘As the important matrix material,epoxy resin has been widely used in the composites for various fields.On account of the poor toughness of epoxy resin limiting their suitability for advanced applications,considerable interests have been conducted to modify the epoxy resin to meet the engineering requirements.In this study,the bio-based polyurethane(PU)modified resin was adopted to modify the pure bisphenol-A epoxy by blending method with various proportions.Aiming to illuminate the curing behavior,mechanical and thermal properties,the blended epoxy systems were characterized by viscosity-time analysis,dynamic mechanical analysis(DMA)at different frequencies and temperatures,mechanical tensile test,thermogravimetric analysis(TGA)and Fourier transform infrared(FT-IR)spectroscopy.The results indicated that the introduction of PU modified epoxy was found to significantly inhibit the viscosity growth rates especially when the content of PU modified epoxy resin is higher than 60%.Notwithstanding the dynamic modulus and T_(g)reduced with the increment of PU modified epoxy,remarkable increment on the elongation at break was found and the flexibility was greatly promoted with the introduction of PU modified epoxy.The proportion of PU modified epoxy in the blends should be put balance considerations to obtain optimal mechanical properties.TGA results and FTIR spectrum demonstrated that the addition of PU modified epoxy did not change the thermal decomposition mechanism and chemical reaction mechanism,but the addition of PU modified epoxy inhibits the curing reaction of epoxy resin by measured and calculated the damping temperature domainT from 35.7℃ to 48.9℃.
基金financially supported by the National Natural Science Funds of China(grant number31470599)the Priority Academic Program Development of Jiangsu Higher Education Institutions,China
文摘Low-basis-weight paper lacks normal strength and stiffness. Waterborne epoxy resin could be employed with oxidized starch to improve paper stiffness through surface sizing. In this study,the mechanism of enhancing stiffness by adding waterborne epoxy resin was fully investigated. The results indicated that through surface sizing with epoxy resin,the paper thickness was preserved,whereas the elastic modulus increased significantly and the epoxy resin had positive impact on single fiber strength. A rigid resin layer and interpenetrating polymer network formed on the surface and in the inner layer of the paper,respectively. The formed resin layer and interpenetrating polymer network strongly supported the paper,leading to the improvement of the elastic modulus and stiffness. The stiffness improvement through surface sizing was mainly due to the formation of a fibrous composite layer and penetration of the sizing agent into the inner layers of the paper. The better the combination between fiber and sizing agent,the higher were the elastic modulus and the stiffness of the whole paper.
基金Project supported by the Advance Research Foundation of China(Grant No.9140Axxx501)the National Defense Advance Research Project,China(Grant No.3151xxxx301)+1 种基金the Frontier Innovation Program,China(Grant No.48xx4)the 111 Project,China(Grant No.B12026)
文摘In this paper, an efficient thermal analysis method is presented for large scale compound semiconductor integrated circuits based on a heterojunction bipolar transistor with considering the change of thermal conductivity with temperature.The influence caused by the thermal conductivity can be equivalent to the increment of the local temperature surrounding the individual device. The junction temperature for each device can be efficiently calculated by the combination of the semianalytic temperature distribution function and the iteration of local temperature with high accuracy, providing a temperature distribution for a full chip. Applying this method to the InP frequency divider chip and the GaAs analog to digital converter chip, the computational results well agree with the results from the simulator COMSOL and the infrared thermal imager respectively. The proposed method can also be applied to thermal analysis in various kinds of semiconductor integrated circuits.
基金Science and Technology Innovation 2030‐“New Generation Artificial Intelligence”major project,Grant/Award Number:2020AAA0108703。
文摘Sentiment analysis is a fine‐grained analysis task that aims to identify the sentiment polarity of a specified sentence.Existing methods in Chinese sentiment analysis tasks only consider sentiment features from a single pole and scale and thus cannot fully exploit and utilise sentiment feature information,making their performance less than ideal.To resolve the problem,the authors propose a new method,GP‐FMLNet,that integrates both glyph and phonetic information and design a novel feature matrix learning process for phonetic features with which to model words that have the same pinyin information but different glyph information.Our method solves the problem of misspelling words influencing sentiment polarity prediction results.Specifically,the authors iteratively mine character,glyph,and pinyin features from the input comments sentences.Then,the authors use soft attention and matrix compound modules to model the phonetic features,which empowers their model to keep on zeroing in on the dynamic‐setting words in various positions and to dispense with the impacts of the deceptive‐setting ones.Ex-periments on six public datasets prove that the proposed model fully utilises the glyph and phonetic information and improves on the performance of existing Chinese senti-ment analysis algorithms.
文摘Mushrooms are well-known to possess a continuum of anticancer metabolites that are vital in the development of anticancer adjuvant drug leads based on natural products. Owing to the fact that conventional cancer therapeutic methods were failed to lessen mortality caused by cancer to the estimated level with occurrence of adverse side effects, anticancer agents isolated from natural mushroom sources unarguably make an experimental research area worth mass focus today. The current study was targeted on in vitro cytotoxicity and in silico predictive pharmacological analysis of a flavonoid compound isolated from Fulvifomes fastuosus mushroom. Targeted compound was isolated from the mushroom using different chromatographic methods and identified by NMR spectrometry and mass spectrometry. Cytotoxicity experiments were carried out using MTT assay and apoptotic cells were identified by ethidium bromide/acridine orange staining. The SwissADME tool, BOILED-Egg construction model and Swiss target protein prediction software have been used to perform in silico predictive pharmacological analysis. The isolated compound has been identified as 2-(3,4-dihydroxyphenyl)-6-[(E)-2-(3,4-dihydroxyphenyl)ethenyl]-5'-methylspiro[2H-furo[3,2-c]pyran-3,2'-furan]-3',4-dione by spectrometric methods. The result of MTT assay showed that 2-(3,4-dihydroxyphenyl)-6-[(E)-2-(3,4-dihydroxyphenyl)ethenyl]-5'-methylspiro[2H-furo[3,2-c]pyran-3,2'-furan]-3',4-dione has potent anticancer activity for hepatoma against Hep-G2 cell line (IC50 = 20.8 μg/ml) being less toxic to normal CC-1 epithelial cells (IC50 = 167.00 μM). The cells treated with compound ex-hibited apoptotic features such as cellular shrinkage, nuclear fragmentation and condensed cytoplasm. In summary, 2-(3,4-dihydroxyphenyl)-6-[(E)-2-(3,4-dihydroxyphenyl)ethenyl]-5'-methylspiro[2H-furo[3,2-c]pyran-3,2'-furan]-3',4-dione has shown potent anticancer properties against hepatoma with less cytotoxicity effect on normal cells. Furthermore, in silico study has revealed that properties of 2-(3,4-dihydroxyphenyl)-6-[(E)-2-(3,4-dihydroxyphenyl)ethenyl]-5'-methylspiro[2H-furo[3,2-c]pyran-3,2'-furan]-3',4-dione may contribute to making a high absorption and clearance of the test compound as not interfering with the therapeutic failure of the compound. The properties of 2-(3,4-dihydroxyphenyl)-6-[(E)-2-(3,4-dihydroxyphenyl)ethenyl]-5'-methylspiro[2H-furo-[3,2-c]pyran-3,2'-furan]-3',4-dione were compatible with well-known anticancer drug lapatinib. In conclusion, 2-(3,4-dihydroxyphenyl)-6-[(E)-2-(3,4-dihydroxyphenyl)ethenyl]-5'-methylspiro[2H-furo[3,2-c]pyran-3,2'-furan]-3',4-dione has a high tendency to act as a good anticancer adjuvant drug in the treatment of hepatoma.
文摘BACKGROUND Colonization with Helicobacter pylori(H.pylori)has a strong correlation with gastric cancer,and the virulence factor CagA is implicated in carcinogenesis.Studies have been conducted using medicinal plants with the aim of eliminating the pathogen;however,the possibility of blocking H.pylori-induced cell differentiation to prevent the onset and/or progression of tumors has not been addressed.This type of study is expensive and time-consuming,requiring in vitro and/or in vivo tests,which can be solved using bioinformatics.Therefore,prospective computational analyses were conducted to assess the feasibility of interaction between phenolic compounds from medicinal plants and the CagA oncoprotein.AIM To perform a computational prospecting of the interactions between phenolic compounds from medicinal plants and the CagA oncoprotein of H.pylori.METHODS In this in silico study,the structures of the phenolic compounds(ligands)kaempferol,myricetin,quercetin,ponciretin(flavonoids),and chlorogenic acid(phenolic acid)were selected from the PubChem database.These phenolic compounds were chosen based on previous studies that suggested medicinal plants as non-drug treatments to eliminate H.pylori infection.The three-dimensional structure model of the CagA oncoprotein of H.pylori(receptor)was obtained through molecular modeling using computational tools from the I-Tasser platform,employing the threading methodology.The primary sequence of CagA was sourced from GenBank(BAK52797.1).A screening was conducted to identify binding sites in the structure of the CagA oncoprotein that could potentially interact with the ligands,utilizing the GRaSP online platform.Both the ligands and receptor were prepared for molecular docking using AutoDock Tools 4(ADT)software,and the simulations were carried out using a combination of ADT and AutoDock Vina v.1.2.0 software.Two sets of simulations were performed:One involving the central region of CagA with phenolic compounds,and another involving the carboxy-terminus region of CagA with phenolic compounds.The receptor-ligand complexes were then analyzed using PyMol and BIOVIA Discovery Studio software.RESULTS The structure model obtained for the CagA oncoprotein exhibited high quality(C-score=0.09)and was validated using parameters from the MolProbity platform.The GRaSP online platform identified 24 residues(phenylalanine and leucine)as potential binding sites on the CagA oncoprotein.Molecular docking simulations were conducted with the three-dimensional model of the CagA oncoprotein.No complexes were observed in the simulations between the carboxy-terminus region of CagA and the phenolic compounds;however,all phenolic compounds interacted with the central region of the oncoprotein.Phenolic compounds and CagA exhibited significant affinity energy(-7.9 to-9.1 kcal/mol):CagA/kaempferol formed 28 chemical bonds,CagA/myricetin formed 18 chemical bonds,CagA/quercetin formed 16 chemical bonds,CagA/ponciretin formed 13 chemical bonds,and CagA/chlorogenic acid formed 17 chemical bonds.Although none of the phenolic compounds directly bound to the amino acid residues of the K-Xn-R-X-R membrane binding motif,all of them bound to residues,mostly positively or negatively charged,located near this region.CONCLUSION In silico,the tested phenolic compounds formed stable complexes with CagA.Therefore,they could be tested in vitro and/or in vivo to validate the findings,and to assess interference in CagA/cellular target interactions and in the oncogenic differentiation of gastric cells.
基金The authors would like to acknowledge the support of the Ph.D.research startup foundation of Guangdong Medical University (2XB14006).
文摘The content of berberine hydrochloride(BH)in compound berberine tablets(CBTs)is subject to strict requirements.Its content is usually measured based on chemical analysis.In this paper,the fluorescence spectral imaging method was used to study the relative content of BH from a physics perspective.By comparing the relative fluorescence intensity of self-made CBTs with di®erent mass percentages of BH,a linear positive relationship was observed between the BH content and the relative fluorescence intensity,and accordingly the quality of CBTs of different brands was evaluated.The results indicate that the fluorescence spectral imaging method can be a simple,fast and nondestructive semi-quantitative analysis method to determine the content of BH in CBTs,and this method has great potential in the quality control of CBTs.
文摘An epoxy penetration technique was used to reproduce and analyze the pitting corrosion process occurred at a steel coupon surface. The samples were exposed to the resin under high vacuum conditions, in order to fulfill the pits caused by the corrosion process. With this technique, a 3D image of the corrosion damages was obtained. Once the image of the damaged surface was obtained, a Scanning Electron Microscope (SEM) was used to analyze the morphology of the pits exhibited by the steel sample. The results were satisfactory, as different parameters such as the diameter, shape and depth of the pits originated, along with the corrosion preferential path, could be established. According to the results, the use of the epoxy penetration technique may be considered as alternating pitting corrosion analysis technique.
