最新刊期
卷 41 ， 期 7 ， 2022
- 摘要：Antioxidants are one of the commonly used additives in plastic products. However，their occurrence and behaviors in air are poorly understood．This research revealed the contamination of a number of plastic additives，including antioxidants，brominated flame retardants，and bisphenol A，in PM2.5 in Guangzhou，China．As for the antioxidants，only their oxidation and degradation products were found in the PM2.5，possibly due to the short atmospheric life of the antioxidants，with total concentrations ranged from 0.64 to 19.3 ng/m3．Higher concentrations were found at sites with intensive chemical and plastic manufacturing．Municipal wastewater treatment plant also has a significant contribution to the degradation products of antioxidants in the air．The correlations between concentrations of plastic additives and meteorological factors are largely determined by the physicochemical properties of the pollutants．Surface solar radiation has the greatest effect on the pollutant levels in the particles，which can promote the enrichment of plastic additives with long half-lives．The lifetime average daily dose of inhalation exposure to the plastic additives was relatively higher for the residents living around the chemical and plastic manufacturing．The incremental lifetime cancer risk of inhalation exposure to decabromodiphenyl ether in Guangzhou is under the acceptable risk level（10－4） and lower than that in other cities of China.关键词：atmospheric particulates;antioxidants;plastic additives;meteorological factors;risk assessment
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发布时间：2022-07-15
Scientific Paper
- 摘要：An ultra performance liquid chromatography－quadrupole－exactive orbitrap mass spectrometry（UHPLC－Q－Exactive－Orbitrap－MS）was developed for the rapid analysis of the chemical components in Zuogui Jiangtang Shuxin formula．The aqueous decoction of Zuogui Jiangtang Shuxin formula was separated on an Xbridge BEH C18（2.1 mm × 100 mm，2.6 μm） column with 0.1% formic acid－water and acetonitrile as mobile phase．The eluent was detected by quadrupole orbitrap high resolution mass spectrometry in ESI positive and negative ion modes．The raw data was processed using Xcalibur 4.3 and Compound Discoverer 3.2 software．A total of 290 chemical components were tentatively identified from the aqueous decoction of Zuogui Jiangtang Shuxin formula，including 224 known compounds with structure classes of flavonoids，phenylpropanoids，phenols，saponins，organic acids，alkaloids，nucleosides，iridoids and oligoses．It is worth noting that the other 66 compounds were detected and identified from Zuogui Jiangtang Shuxin formula for the first time，which were mainly amino acids/small peptides．This developed method could be used for rapid and accurate analysis of the chemical components in Zuogui Jiangtang Shuxin formula，which could provide a reference for further research on the therapeutic material basis of Zuogui Jiangtang Shuxin formula and guiding the rational use of drugs in clinical practice as well as later experimental studies．关键词：Zuogui Jiangtang Shuxin formula;ultra performance liquid chromatography－quadrupole－exactive orbitrap mass spectrometry;chemical components;small peptides
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发布时间：2022-07-15 - 摘要：Schiff base platinum（Ⅱ） complexes are considered to be a promising red phosphorescent organic light-emitting diode（OLED） material in biomedical display，telecommunication security and other fields due to their stability，modifiability and easy synthesis．However，they often leads to some problems such as low photoluminescence quantum yield（PLQY） and low device performance caused by aggregation quenching due to their obvious structural planarity．Introducing groups with larger steric hindrance at the periphery of the Schiff base may effectively improve the above problems．In this study，the corresponding ligands were synthesized and further coordinated with K2PtCl4 under alkaline conditions to synthesize two novel Schiff base platinum（Ⅱ） complexes SPtA and SPtB with peripherally introduced large sterically hindered phenyl groups．The compounds were characterized by nuclear magnetic resonance（NMR） and high-resolution mass spectrometry（HRMS）. Theoretical calculations for the compounds were performed using time-dependent density functional theory （TDDFT）．The thermodynamic properties of the compounds were studied by thermogravimetric analysis（TGA） and differential scanning calorimetry（DSC）．The electrochemical properties of the compounds were determined by cyclic voltammetry（CV）．Meanwhile，the optical properties such as absorption and emission spectra，PLQY，and phosphorescence lifetime of the compounds were studied．Using SPtB as the doped guest material，a series of devices were fabricated by vacuum evaporation method to study the optoelectronic properties．The results showed that the thermal decomposition temperatures（Td） of SPtA and SPtB are 395 ℃ and 420 ℃，which are higher thermal decomposition temperatures，while the maximum emission wavelengths are both 632 nm，and PLQYs were 45% and 47%，which were higher than those of reference molecule. In the following device studies，the effects of the host，thickness，and guest doping ratio of the light-emitting layer on the device performance were compared．Finally，with tris（4-carbazoyl-9-ylphenyl）amine （TCTA） and 1，3，5-tri（m-pyrid-3-yl-phenyl）benzene （TmTyPB） as mixed hosts，the thickness of the light-emitting layer was 30 nm，the doping concentration of SPtB was 3%，and the optimal device structure was obtained．It had a maximum current efficiency of 10.5 cd/A，a maximum power efficiency of 7.2 Im/W and a maximum external quantum efficiency（EQE） of 9.6%．The maximum emission wavelength of the device was maintained at 630 nm under different voltages，and the CIE coordinates were （0.64，0.35），which was a red phosphorescent OLED device with high color purity．Studies showed that the introduction of large sterically hindered phenyl groups at the periphery of Schiff base platinum（Ⅱ） complexes could reduce molecular aggregation and improve molecular performance．关键词：Schiff base;platinum （Ⅱ） complex;photoelectric properties;red phosphorescence
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发布时间：2022-07-15 - 摘要：Plants from the genus Syzygium have significant medicinal and edible application values. Syzygium brachythyrsum（S.brachythyrsum） has been widely used as a traditional ethnic Chinese medicine in southwest China．However，the knowledge about its chemical compositions and pharmacological effects is still unknown．Several new bergenins derivatives from this medicinal plant were isolated for the first time in the previous study．In the present work，a rapid and effective method was established for the identification and characterization of bergenins derivatives in S.brachythyrsum based on ultrahigh performance liquid chromatography－Q－exactive orbitrap mass spectrometry（UHPLC－Q－Exactive－MS）．The methanol extract of S.brachythyrsum was separated on a Waters ACQUITY UPLC HSS T3 column（1.8 μm，2.1 mm × 100 mm），using acetonitrile－water containing 0.1% formic acid as mobile phase，then detected by UHPLC－Q－Exactive－MS in negative mode．Based on the combination of the high-resolution mass determination，the fragmentation behaviors and fragmentation pattern of model compounds，and diagnostic fragment ions filtering strategy，54 compounds including 34 bergenins derivatives were identified or tentatively characterized from S.brachythyrsum．These bergenins derivatives mainly composed of O-galloyl，feruloyl，sinapoyl，coumaroyl，syringyl，caffeoyl，and hydroxy benzoyl substituted bergenins and norbergenins．Furthermore，a series of hexahydroxydiphenoyl（HHDP） substituted bergenins were identified as potential new natural products．All these bergenin derivatives were found in the Syzygium genus for the first time．The results of this paper demonstrated for the first time that S.brachythyrsum is a rich resource of bergenin derivatives，and it provides a reference for further research and utilization of Chinese herbal medicine S. brachythyrsum.关键词：Syzygium;Syzygium brachythyrsum;liquid chromatography－mass spectrometry（LC－MS）;bergenin
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发布时间：2022-07-15 - 摘要：The effects of different processing and drying methods on overall metabolites of Eucommiae Cortex were investigated. First of all，the rough skin on the surface of fresh Eucommiae Cortexes were scraped off，some of them were stored in the refrigerator at －80 ℃，and the rest were treated with three kinds of different processing and drying methods，including stacking “sweating”，scalding “sweating” and drying in the shade. Secondly，three kinds of processed and dried Eucommiae Cortex，including fresh Eucommiae Cortex samples，were freeze-dried，crushed and then extracted with 70% methanol. The metabolites of Eucommiae Cortex were analyzed by ultra performance liquid chromatography－tandem mass spectrometry（UPLC－MS/MS） with electrospray ionization（ESI） ion source，and positive or negative ion mode was used for data collection. The collected data were processed in a series of ways，including peak extraction，peak integration，normalization，etc. After that，the molecular weights of metabolites were obtained according to the first-order mass spectrometry information. And the characteristic ion fragments of metabolites were obtained with the second-order mass spectrometry information，so as to realize the structural analysis of modern metabolites. By searching Metware database（MWDB），human metabolome database（HMDB），MassBank and other databases，the qualitative analysis of metabolites in Eucommiae Cortex was carried out. Finally，the metabolite data were analyzed by principal component analysis（PCA），orthogonal partial least squares discriminant analysis（OPLS－DA） and other multivariate statistical analysis. On the basis of variable importance in the projection（VIP） obtained by OPLS－DA model and fold change（FC），the different metabolites in Eucommiae Cortex obtained by different processing and drying methods were selected. The relative contents of metabolites were characterized by relative peak area，and the relative contents of different metabolites were compared. Results showed that the Eucommiae Cortex samples of the four groups could be clearly distinguished in the PCA score diagram. More than 170 metabolites in Eucommiae Cortex obtained by three kinds of processing and drying methods changed significantly，compared with those in fresh Eucommiae Cortex. And more than 80% of the metabolites were up-regulated. Among the Eucommiae Cortexes obtained by three kinds of processing and drying methods，the number of up-regulated metabolites of stacking“sweating”Eucommiae Cortex was higher，followed by that of drying in the shade. In addition，stacking“sweating”was conducive to the retention of lignans，coumarins，iridoids and quinones，drying in the shade was conducive to the retention of phenolic acids，and scalding“sweating”was conducive to the retention of flavonoids. By comparing the different metabolites of Eucommiae Cortex with different processing and drying methods，a scientific basis was obtained for exploring the quality formation mechanism of Eucommiae Cortex and optimizing its processing methods.关键词：Eucommiae Cortex;ultra performance liquid chromatography－tandem mass spectrometry （UPLC－MS/MS）;“sweating”;processing method;metabolomics
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发布时间：2022-07-15 - 摘要：The increasing proliferation and quick upstate of the synthetic new drugs have brought huge challenges to the anti-narcotics units in field identification and rapid detection．It is of positive significance to seek a fast，accurate and low-cost on-site detection method for the effective control of the new drugs．In the paper，a novel particle swarm optimization－extreme learning machine（PSO－ELM） algorithm combined with a hand-held near-infrared（NIR） spectroscopy was applied to build the source recognition models for methamphetamine and heroin drugs，which was also compared with the traditional linear discriminant analysis（LDA） algorithm and support vector machine（SVM） algorithm．The experimental results showed that the PSO－ELM source recognition models could obtain the best classification results and computational efficiency．The proposed method could recognize the different sources of the drugs，provide some valuable clues for determining the nature of the case in the prohibition of actual combat．关键词：near-infrared spectroscopy（NIR）;drugs;extreme learning machine（ELM）;source recognition
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发布时间：2022-07-15 - 摘要：Colorectal cancer（CRC） is one of the most malignant tumors in the world and the main cause of cancer death．Traditional diagnostic methods for CRC patients have poor performance owing to their low sensitivity or specificity．The aims of this study are to explore the lipid biomarkers and the metabolic pathways of CRC for better understanding of its pathogenesis as effective and convenient biomarkers for CRC diagnosis are still lacking，and there are relatively few of serum lipidomic study on CRC for the time being．Therefore，the lipidomics analysis on serum samples from 50 normal controls and 50 CRC patients was performed by ultra-high performance liquid chromatography tandem Q Exactive orbitrap mass spectrometry．Lipidomic data was analyzed by univariate statistical analysis，including Mann－Whitney U or Student’t test and multiple statistical analysis，including principal component analysis（PCA） and orthogonal partial least squares discriminant analysis（OPLS－DA）．In addition，the established OPLS－DA model was validated by 200 times permutation test to exam its fitness and reliability．Through the comparison of lipid profiles，there were significant differences in the serum lipidomics profiles between two groups，and 155 differential lipids were found responsible for their discrimination based on P < 0.05 and fold change > 1.5 or < 0.67．Most of them belonged to phosphatidylcholine（PC） and triacylglycerol（TAG） with constituent ratio of 30.32% and 27.10%，respectively，indicating that dysregulation of PC and TAG metabolism could be closely related with CRC formation．Then，the diagnostic ability of differential lipids was evaluated by receiver operating characteristic curve（ROC） analysis．A total of 9 differential lipids with high specificity and sensitivity as well as high diagnostic performance（AUC > 0.80） for CRC diagnosis were selected and identified by using mzCloud and LipidBlast database，including the species of palmitoyl ethanolamide，palmitic acid，sphingosine，sphingomyelin（SM）d40∶3，SM d36∶0，TAG 58∶1，PC 34∶2，PC 36∶6，PC 38∶7．These lipid species，served as the potential diagnostic biomarkers of CRC，exibited a great clinical application potential in serum-based lipidomics screening of CRC．Meanwhile，the study also provided some basic data that could be used to profile the lipid characteristics and explore the mechanism of CRC.关键词：colorectal cancer;ultra-high performance liquid chromatography tandem Q exactive orbitrap mass spectrometry;lipidomics;serum;biomarkers
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发布时间：2022-07-15 - 摘要：A column switching liquid chromatography was developed for the analysis of aconitine-type alkaloids including aconitine（AC），mesaconitine（MA），hypaconitine（HA），benzoylaconine（BAC），benzoylmesaconine（BMA），benzoylhypaconine（BHA） and nine ginsenosides in Shenfu injection（SFI）．Aconite-type alkaloids were enriched on an online SPE column by the interaction of strong cation exchange，and purified by the optimized eluting program．Eluting conditions were confirmed through investigating the transferring solvent and eluting time．A Zorbax SB－C18 was chosen as the analytical column，with acetonitrile and ammonium acetate as mobile phases．Meanwhile，an EC－C18 belonged to core-shell particles was used to analyze ginsenoside in SFI．Through the investigation of column oven and gradient program，the optimized conditions were confirmed．The matrix interference was removed to improve the relative response in chromatogram by column switching．The analytical processes for alkaloids and ginsenosides were switched automatically via valve switching．The satisfactory resolutions could be achieved for the aconitine-type alkaloids and ginsenosides in SFI sample．The methodology investigation showed good linearity（r2 > 0.999），precision（RSD < 2.0%） and better reproducibility（RSD < 2.0%）．The limits of detection（LODs） for six target alkaloids were from 4.0 to 8.2 ng/mL．The average recoveries for six target alkaloids ranged from 95.1% to 98.6%．For nine ginsenosides，the recoveries were from 91.7% to 104%．It was an effective way to remove a large amount of matrix interference by the constructed online SPE method based on column switching LC，which could complete the rapid quantitation of three monoester alkaloids and nine active ginsenosides in SFI．The proposed method also realized the limit inspection of three diester alkaloids，and it could be used in practical quality evaluation on SFI．关键词：column switching liquid chromatography;online SPE;benzoylmesaconine;aconitine gensinoside Ro;Shenfu injection
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发布时间：2022-07-15 - 摘要：A gas chromatography－mass spectrometry（GC－MS） was applied to investigate the mass fragmentation characteristics of 9 indazole-3-carboxamide analogues synthetic cannabinoids in electron ionization（EI），including MDMB－CHMINACA，5F－AB－PINACA，5F－AMB，AB－CHMINACA，AB－FUBINACA，AB－PINACA，MDMB－FUBINACA，AMB－FUBINACA and ADB－BUTINACA．The obtained mass spectra were analyzed and the EI fragmentation patterns of indazole-3-carboxamide analogues synthetic cannabinoids were speculated．Results showed that in the EI mode，the C—N cleavage of the amide group connected to the indazole ring at position 3 is the main fragmentation pathway，and the McLafferty rearrangement was happened during the fragmentation．The main fragmentation ions and mass fragmentation characteristic of indazole-3-carboxamide analogues synthetic cannabinoids in EI modes were summarized in this paper，which is useful for identification on the new psychoactive substances of unknown indazole-3-carboxamide analogues synthetic cannabinoids in practical work．关键词：new psychoactive substances;synthetic cannabinoids;indazole-3-carboxamide;gas chromatography;mass fragmentation characteristics
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发布时间：2022-07-15 -
Analysis of Diarylheptanoids in Zingiberaceae by UPLC－ ESI－Q－TOF MS Combined with Fragmentation Rule
摘要：According to the mass spectrum data of the standard substance，the fragmentation rule of diarylheptanoid was discussed，and the component in zingiberaceae plants was analyzed by the fragmentation rule．The standard samples were injected by syringe pump．The mass spectrum data of 11 standards were obtained by high resolution and high accuracy electrospray ionization quadrupole time-of-flight tandem mass spectrometry（ESI－Q－TOF MS） in positive ion mode（ESI+）．On the basis of the obtained standards mass spectrum data，the cracking behaviors of the standards were analyzed．According to the cracking behaviors of standard samples，four kinds of cracking pathways of diarylheptanoid were summarized，and the fragmentation rule of diarylheptanoid was summarized．Based on the fragmentation rule of diarylheptanoid standards，an ultra-high performance liquid chromatography－electrospray ionization quadrupole time-of-flight mass spectrometry（UPLC－ESI－Q－TOF MS） was established for the rapid identification of diarylheptanoid components in ginger peel，Amomum tsao－ko and Alpinia oxyphylla Miq. 14， 11 and 10 of this kind of components were successfully identified from them，respectively．The obtained results verified the feasibility of this method．The method is accurate，reliable and efficient，and it could be used for rapid identification and analysis of diarylheptanoids in zingiberaceae plants．关键词：diarylheptanoids;fragmentation rule;UPLC－ESI－Q－TOF MS;zingiberaceae- 5
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发布时间：2022-07-15
Scientific Papers
- 摘要：Mg2+ and rhein were used as precursor materials to prepare rhein-carbon dots. Based on the quenching effect of moisture on the fluorescence signal of rhein-carbon dots，a simple and rapid method for the determination of moisture content in tobacco leaf processing was established with the help of smartphone RGB signal acquisition technique. The fluorescence quenching mechanism showed that the interaction between the protic solvent（water） and the aprotic solvent（DMSO） could significantly quench the fluorescence signal of rhein-carbon dots. There was a good linear relationship between fluorescence quenching effect and the water content in the range of 30－1 000 mg，with a detection limit of 5 mg. Using a smartphone to collect signals and reading RGB values through software，the results showed that there was a good linear relationship between the water content and the R value within the linear range （r2 = 0.990 2）. The method could realize rapid on-site determination of water content in tobacco leaf processing，and the results met the actual determination requirements. With the characteristics of simplicity，stability and accuracy，this method provides a new research strategy for water detection techniques and related probe design.关键词：carbon dots;moisture determination;rhein;smartphone;colorimetry;fluorescent probe
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发布时间：2022-07-15 - 摘要：The quality evaluation on tobacco is an important work as it is a high-value attribute product．Therefore，it is of a certain application value to ultilize intelligent means for efficient classification of tobacco．Based on near infrared spectroscopy（NIRs），937 tobacco samples from 13 provinces from 2016 to 2018 were used to compare the extreme learning machine（ELM） model effects of three variable screening methods，including competitive adaptive reweighted sampling（CARS） method，Monte Carlo uninformed variable elimination（MC－UVE） method and random frog（RF） algorithm．Compared with partial least squares－discriminant analysis（PLS－DA），the advantages of ELM model were verified．The ELM model was optimized by teaching-learning-based optimization（TLBO） algorithm，thus a TLBO－ELM classification model for flue-cured tobacco samples was established．Results showed that the classification accuracy of the validation set was 90.16%．The external verification effect of the testing set was satisfactory，and the TLBO－ELM model had fast convergence speed and strong generalization ability，which could be applied to the classification of flue-cured tobacco．NIRs combined with TLBO to optimize ELM provides a new idea for intelligent tobacco classification.关键词：near infrared spectroscopy;teaching-learning-based optimization algorithm;extreme learning machine;tobacco;grade determination
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发布时间：2022-07-15 - 摘要：Isoniazid（INH） is an indispensable drug in the treatment of tuberculosis at this stage．The determination of INH content is of great significance in drug quality control and drug safety．In this paper，carbon dots（CDs） were synthesized rapidly by a microwave method using citric acid as the carbon source and thiourea as the nitrogen source．The carbon dots emit blue fluorescence under UV light，which have the advantage of biocompatibility and high stability．The carbon dots were mixed with manganese dioxide nanosheets（MnO2） to form a fluorescent nanoprobe for the sensitive detection of INH．The morphology，composition and surface groups of the carbon dots and manganese dioxide nanosheets were characterized by transmission electron microscopy（TEM），X ray photon spectroscopy（XPS），X ray diffraction（XRD），Fourier transform infrared spectroscopy（FT－IR），ultraviolet－visible spectroscopy（UV－Vis） and fluorescence spectroscopy，respectively．TEM results indicated that the carbon dots were nearly spherical with particle sizes of 2.0－3.0 nm，while the manganese dioxide nanosheets had a typical two-dimensional flake morphology．Fourier transmission infrared spectroscopy revealed that there were hydroxyl，amino，and carboxyl groups on the surface of carbon dots．The fluorescence spectrum of carbon dots demonstrated a maximum emission at 445 nm with an excitation wavelength of 360 nm．Meanwhile，manganese dioxide nanosheets had a wide absorption band of 250－600 nm，which had a large overlap with the fluorescence emission spectra of carbon dots．The fluorescence of carbon dots was quenched by fluorescence resonance energy transfer（FRET） between carbon dots and manganese dioxide nanosheets．After the addition of trace INH，the redox reaction between INH and manganese dioxide nanosheets occurred，which degraded manganese dioxide nanosheets and restored the fluorescence of carbon dots．This allowed the development of a nanoprobe for the quantitative detection of INH，which showed good sensitivity and selectivity for INH．The fluorescence intensity of carbon dots at 360 nm excitation under different pH of PBS solution，different concentration of sodium chloride solution and UV irradiation was studied．The experimental results showed that carbon dots had good stability．After optimization of the experimental conditions， the linear range of the nanoprobe for INH detection in pH 7.4 PBS buffer solution was 0.5－60 μmol/L，with a detection limit of 0.02 μmol/L．Selectivity and interference experiments presented that the nanoprobe was highly selective for INH．Moreover，common metal ions， amino acids，and sugars did not interfere with INH detection．The CDs/MnO2 probe was used for the determination of INH in normal human blood，urine samples，and tablets．The recoveries of blood samples，urine samples and tablets were 94.8%－116%，99.0%－105% and 96.8%－102%，respectively．Relative standard deviations（RSDs） were less than 5% for all samples．It is highly sensitive，selective，simple to prepare，economical，and environmentally friendly．The probe provides a new idea for the detection of INH and has a promising application prospect in the detection of biological samples．关键词：CDs/MnO2 nanoprobe;isoniazid（INH）;fluorescence resonance energy transfer（FRET）;anti-tuberculosis drug
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发布时间：2022-07-15 - 摘要：The near infrared spectroscopy technology has been widely applied to the quantitative analysis in tobacco industry because of its advantages of rapidness and non-destructiveness．However，the accuracy and robustness of the original model may deteriorate when predicting samples with new variations．When samples are obtained from different harvest years and different environmental conditions，new variations will be introduced．Therefore，there is a need to maintain the predictive performance of the original model when it works on a new batch．In this study，a method called semi-supervised parameter-free calibration enhancement（SS－PFCE） was used to update the original model．The regression coefficient of original model was corrected by constrained optimization．The original model for total sugar determination was firstly developed with the tobacco samples of 2016，which showed a predicted correlation coefficient（Rp） of 0.997 8 and a root mean square error of prediction（RMSEP） of 0.310 8．After updating the model by the SS－PFCE method，the total sugar contents in the samples of 2017，2018 and 2020 years were predicted，respectively．The Rp values of the three test sets were improved by 0.13%，1.32% and 4.29%，and the RMSEP were decreased by 15.26%，58.69% and 36.53%，respectively，compared with the non-updated model．Furthermore，the updated model by the SS－PFCE approach offered a better predictive performance than re-modeling method，while significantly reduced modeling costs．The results of this study showed that the SS－PFCE method could maintain the prediction accuracy for tobacco samples of different years efficiently，and it is of great practical application value in industrial production．关键词：near infrared spectroscopy;model update;tobacco;semi-supervised parameter-free calibration enhancement（SS－PFCE）
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发布时间：2022-07-15 - 摘要：8-Oxyguanine DNA glycosylase（OGG1） is an impotant DNA repaired enzyme，which can excise 8-oxyguanine（8-oxoG），a marker of damaged DNA．Meanwhile，it is implicated in the etiology of many kinds of cancers．Here，a fluorescence sensor based on the photo-induced electron transfer（PET） effect was constructed to detect the quantities of OGG1 which depended on the change of fluorescence intensity before and after addition of the OGG1 in the system．The carefully designed DNA signal probe contained an internal 8-oxoG site and 5' end carboxyfluorescein tag，a complementary sequence as the quenching group with 3' terminal containing multiple G base．This method was simple，sensitive and specific，and it was used for the detection of OGG1 in human serum samples．The results showed that there was a good linear relationship between the fluorescence intensity change of the system and OGG1 in the concentration range of 0－60 U/mL，with a detection limit of 0.7 U/mL．The recoveries for OGG1 in spiked human blood serum samples ranged from 99.1% to 105%，with the relative standard deviations（RSDs） of 1.0%－4.3%．The sensor has the advantages of good selectivity，simple operation and low cost．关键词：8-oxyguanine DNA glycosylase;photo-induced electron transfer;fluorescence sensor
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发布时间：2022-07-15 - 摘要：Increase in the concentration of metal copper and iron ions in the insulation oil for running transformer not only leads to the deepening of the corrosion of the high-voltage copper windings and iron cores immersed in the transformer oil and reduction of insulation performance of the transformer oil，but also causes the increase in the insulation aging ability of transformer oil-paper of metal ion catalysis．In order to track the concentration of copper and iron ions in the transformer oil in operation，and reduce sudden transformer insulation failures caused by the accelerated aging of transformer oil-paper insulation，an inductively coupled plasma mass spectrometry（ICP－MS） with reverse phase switchable hydrophilic solvent liquid－liquid microextraction was developed for the simultaneous separation，enrichment and determination of Cu2+ and Fe3+ in transformer insulating oil．The switchable hydrophilic solvent triethylamine（TEA） was used as the extractant，and nitric acid solution was used as the trigger. The extraction conditions were optimized as follows：50 µL of TEA was used to extract 25 mL of transformer oil sample，the molar ratio of TEA to HNO3 was 1∶1.5，the concentration of HNO3 was 0.60 mol/L，the reaction time of vortex extraction and the hydrophilicity switching reaction were both 5 min，the lower water extract phase could be directly injected for determination after centrifugation was performed at 4 500 r/min for 5 min. There were good linearities for Cu2+ and Fe3+ in the range of 0.100－10.0 µg/L，with their correlation coefficients（r2） of 0.999 6．The detection limits for Cu2+ and Fe3+ were 16.8 ng/L and 29.0 ng/L，respectively，and the enrichment factors were about 24 times．The concentration of Cu2+ and Fe3+ in the oil samples of the simulated aging transformer were determined．And the spiked recoveries of Cu2+ and Fe3+ ranged from 93.3% to 112%，with relative standard deviations（RSDs） of 3.6%－5.6%．There is no significant difference between the sample pretreatment method established in this paper and the ashing method used in the current standard，and it is helpful for the online tracking determination of trace Cu2+ and Fe3+ in the operating transformer insulating oil．关键词：reversed phase switchable hydrophilicity solvent;liquid－liquid microextraction;copper and iron ions;transformer oil;inductively coupled plasma mass spectrometry（ICP－MS）
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发布时间：2022-07-15 - 摘要：In this paper，flow cytometric analysis，cell counting kit-8（CCK-8） and real time cellular analysis（RTCA） were used to detect cell viability before and after flow cytometric sorting，respectively. The experimental operation and statistical analysis of the three methods were compared comprehensively. The result showed that the apoptosis percentages for cells determined by flow cytometric analysis were （3.85 ± 0.008）% in the group after sorting and （14.09 ± 0.021）% in the group before sorting. And the apoptosis percentage for cells after sorting was lower than that before sorting，with a statistical difference（P） less than 0.05. Further statistical analysis for the proportion of living cells before and after sorting showed that the proportion of living cells after sorting was higher than that before sorting，with a significant statistical difference（P） less than 0.001. The CCK-8 assay showed that the group after sorting had higher cell proliferation viability than the group before sorting（P < 0.001）. RTCA assay showed a highly significant statistical difference（P < 0.000 1） in the continuous proliferation activity of the cells after sorting. Compared to the assays of flow cytometric analysis and CCK-8，RTCA method has a low request of cell numbers，recyclable，easy operation，labeling-free，high detection sensitivity，which displays a real-time dynamic cell growth curve suitable for studying the long-term dynamic changes of cell viability after sorting. Furthermore，RTCA could be used as a method for the functional studies of cells after basic and clinical sorting.关键词：real time cellular analysis;flow cytometric analysis;flow cytometric sorting;CCK-8;cell viability
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发布时间：2022-07-15
Experimental Techniques and Methods
- 摘要：Electrochemical sensors have attracted widespread attention in the field of severe acute respiratory syndrome coronavirus 2（SARS－CoV－2） detection owing to their characteristics of high sensitivity，portability，high robustness，miniaturization，low cost，no pretreatment and rapid detection．Firstly，the components of SARS－CoV－2，the causative bacterium of COVID－19 are roughly described in this paper．Secondly，the researches on three electrochemical biosensors that can specifically detect SARA－CoV－2 based on the spike protein on the surface，internal nucleocapsid protein and ribonucleic acid（RNA） are reviewed．Moreover，the key parameters such as limit of detection，time and dynamic detection range of the three types of electrochemical biosensors are comprehensively analyzed. Meanwhile，the advantages and disadvantages of electrochemical biosensors are analyzed when compared with other methods for SARA－CoV－2 detection．Finally，it is pointed out that the improvement of electrochemical biosensor performance could be realized in the future by optimizing detection electrode materials，reaction conditions and modification detection probes，which is of important significance for early detection，early isolation and early treatment of COVID－19 patients，and even providing a strong support for the design of rapid diagnosis of COVID－19 equipment．关键词：severe acute respiratory syndrome coronavirus 2（SARS－CoV－2）;electrochemical biosensor;spike protein;nucleocapsid protein;ribonucleic acid（RNA）;COVID－19
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发布时间：2022-07-15 - 摘要：Heavy metals are ubiquitously present in the natural environment．Due to their high toxicity，different occurrences and resistance to microorganism decomposition，they are highly prone to accumulate and cause harm when they enter into living organisms through various pathways．The differences in the distribution and occurrence of heavy metals in organisms are the key factors that determine their biological effects，thus understanding these key factors is the basis for exploring their toxicological mechanisms．In-situ imaging technology has received widespread attention as it is designed to spatially identify heavy metals in organisms，which enables the visual evaluation of heavy metal content，distribution，transformation，as well as intake and excretion．The basic principles and applications of in-situ imaging methods for heavy metals are summarized in this paper，including laser ablation inductively coupled plasma mass spectrometry（LA－ICP－MS），synchrotron radiation and metal sensing fluorophore imaging，and their respective technical characteristics and application scenarios are compared．The perspectives on future development of in-situ imaging of heavy metals in living organisms are also provided．关键词：heavy metals;in-situ imaging technology;laser ablation inductively coupled plasma mass spectrometry（LA－ICP－MS）;synchrotron radiation;metal sensing fluorophore
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发布时间：2022-07-15 - 摘要：Trace impurities in hydrogen for hydrogen fuel cell vehicles will affect the performance of hydrogen fuel cells．The limits of trace impurities have been strictly stipulated in domestic and foreign standards．Ion chromatography（IC） has the characteristics of simple operation，rapid analysis，high sensitivity，good selectivity，and multi-component detection. The analysis of some indexs by IC were involved in ISO 14687－2∶2012，SAE J2719∶2015 and GB/T 37244－2018．At present，IC has been widely used in the field of gas analysis such as ambient air，stationary source emission，natural gas and flue gas．The analysis of hydrogen fuel impurities is still in its infancy．In this paper，the analytical methods for total halogenated compounds，formic acid，ammonia and total sulfur in hydrogen fuel and other gas analysis fields are reviewed，and IC is compared with different analytical techniques．Based on the application progress of IC in other gas impurity analysis fields，its application in hydrogen impurity analysis for hydrogen fuel cell vehicles is prospected.关键词：ion chromatography;fuel cell vehicles;hydrogen;trace amount of impurities
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发布时间：2022-07-15
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