The performance and operation stability of proton exchange membrane fuel cells(PEMFCs)are closely related to the transportation of reactants and water management in the membrane electrode assembly(MEA)and flow field.I...The performance and operation stability of proton exchange membrane fuel cells(PEMFCs)are closely related to the transportation of reactants and water management in the membrane electrode assembly(MEA)and flow field.In this paper,a new three-dimensional wave parallel flow field(WPFF)in cathode was designed and analyzed throughout simulation studies and an experimental method.The experimental results show that the performance of PEMFC with WPFF outperforms that of PEMFC with straight parallel flow field(SPFF).Specifically,the peak power density increased by 13.45%for the PEMFC with WPFF as opposed to PEMFC with SPFF.In addition,the flow field with area of 11.56 cm^(2) was formed by the assembly of transparent end plate used for cathode and the traditional graphite plate used for anode.To understand the mechanism of the novel flow field improving the performance of PEMFC,a model of PEMFC was proposed based on the geometry,operating conditions and MEA parameters.The thickness of gas diffusion layers(GDL),catalytic layers(CL)and proton exchange membrane were measured by scanning electron microscope.The simulation result shows that compared with SPFF,the WPFF based PEMFC promote the oxygen transfer from flow channel to the surface of CL through GDL,and it was beneficial to remove the liquid water in the flow channel and the MEA.展开更多
[Objective]This study aimed to research the effect of metallothionein on cell cycle,apoptosis rate and subsets distribution of lymphocytes in peripheral blood of dairy cows under heat stress,so as to perfect the regul...[Objective]This study aimed to research the effect of metallothionein on cell cycle,apoptosis rate and subsets distribution of lymphocytes in peripheral blood of dairy cows under heat stress,so as to perfect the regulative mechanism researches of MT to anti-heat stress.[Method]Twenty lactating Chinese Holstein cows were randomly divided into four groups(A,B,C and D),and injected with 0,4.0,8.0 and 12.0 mg Zn-metallothionein,respectively by intravenous route.Blood samples were collected at 1st,16th,31st,46thand 61stday,and the dynamic changes of cell cycle,apoptosis rate and subsets distribution of lymphocytes were determined.[Result]The apoptosis rate of cells in group B and C was lower than those in group A by 26.63%(P>0.05)and 24.84%(P>0.05)respectively.The number of cells in the G0/G1phage in trial groups was increased and the number of cells in the S and G2/M phages tended to decrease,but there were no significant differences(P>0.05).The number of CD3+T cell in three trial groups was greater than those in group A by 7.02%(P>0.05),5.45%(P>0.05)and 3.85%(P>0.05)respectively,while the number of CD4+T cell in trial groups was higher than those in control group by31.04%(P<0.05),35.68%(P<0.05)and 39.34%(P<0.05)respectively.The number of CD8+T cell and the levels of CD4+/CD8+in trial groups were increased observably,but significant difference(P<0.05)was observed in the levels of CD4+/CD8+between groups A and C only.It demonstrated that exogenous Zn-metallothionein can decrease apoptosis rate,improve cell cycle and regulate subsets distribution of lymphocytes in dairy cattle in a dose-dependent manner.[Conclusion]This study will provide scientific basis for safe utilization of MT in dairy industry.展开更多
The aim is to explore the predictive value of salivary bacteria for the presence of esophageal squamous cell carcinoma (ESCC). Saliva samples were obtained from 178 patients with ESCC and 101 healthy controls, and all...The aim is to explore the predictive value of salivary bacteria for the presence of esophageal squamous cell carcinoma (ESCC). Saliva samples were obtained from 178 patients with ESCC and 101 healthy controls, and allocated to screening and verification cohorts, respectively. In the screening phase, after saliva DNA was extracted, 16S rRNA V4 regions of salivary bacteria were amplified by polymerase chain reaction (PCR) with high-throughput sequencing. Highly expressed target bacteria were screened by Operational Taxonomic Units clustering, species annotation and microbial diversity assessment. In the verification phase, the expression levels of target bacteria identified in the screening phase were verified by absolute quantitative PCR (Q-PCR). Receiver operating characteristic (ROC) curves were plotted to investigate the predictive value of target salivary bacteria. LEfSe analysis revealed higher proportions of Fusobacterium, Streptococcus and Porphyromonas, and Q-PCR assay showed significantly higher numbers of Streptococcus salivarius, Fusobacterium nucleatum and Porphyromonas gingivalis in patients with ESCC, when compared with healthy controls (all P < 0.05). The areas under the ROC curves for Streptococcus salivarius, Fusobacterium nucleatum, Porphyromonas gingivalis and the combination of the three bacteria for predicting patients with ESCC were 69%, 56.5%, 61.8% and 76.4%, respectively. The sensitivities corresponding to cutoff value were 69.3%, 22.7%, 35.2% and 86.4%, respectively, and the matched specificity were 78.4%, 96.1%, 90.2% and 58.8%, respectively. These highly expressed Streptococcus salivarius, Fusobacterium nucleatum and Porphyromonas gingivalis in the saliva, alone or in combination, indicate their predictive value for ESCC.展开更多
Dear Editor,Previous studies have proved that regulatory T cell(Treg)insufficiency contributed to the development of autoimmune conditions including systemic lupus erythematosus(SLE).Conventional immunosuppressive tre...Dear Editor,Previous studies have proved that regulatory T cell(Treg)insufficiency contributed to the development of autoimmune conditions including systemic lupus erythematosus(SLE).Conventional immunosuppressive treatment was reported to downregulate beneficial Tregs together with pathogenic effector immune cells,which may impede a rapid achievement of optimal therapeutic effects.展开更多
The content of biothiols in cells is highly associated with the occurrence and development of several diseases.However,due to their active chemical properties,thiol-contained molecules are normally volatile during the...The content of biothiols in cells is highly associated with the occurrence and development of several diseases.However,due to their active chemical properties,thiol-contained molecules are normally volatile during the detection process,rendering precise analysis of intracellular biothiols challenging.In this study,5,5’-dithiobis-(2-nitrobenzoic acid)(DTNB)is covalently modified on the surface of gold nanorods(AuNRs),constructing sensing substrates for in situ Raman imaging analysis of biothiols in cells.Au NRs are able to serve as ideal surface-enhanced Raman scattering substrates,and thus Raman signals of DTNB are greatly amplified by AuNRs.Meanwhile,the disulfide bond of DTNB can be broken by thiols,thereby releasing part of DTNB from the surface of AuNRs.As a result,three kinds of main biothiols are sensitively quantified with DTNB-modified AuNRs according to the variation of Raman signals,and DTNB-modified Au NRs exhibit far better analytical performance than a commercial probe.In addition,the sensing substrates can be readily delivered to cytoplasm with the transmembrane of Au NRs,and are capable of responding to biothiols in cells.Notably,the Raman approach is established by the breaking of chemical bonds rather than the aggregation of substrates,which is more inclined to analyze intracellular biothiols with a desirable spatial resolution.Therefore,fluctuation of biothiols in glioma cells is evidently observed via Raman imaging.Overall,this work provides an alternative strategy for designing Raman sensors to visualize active molecules in cells.展开更多
The low-oxygen environment restricts the exploitation of mineral resources on plateaus and affects miner’s safety.This paper proposes an oxygen-enrichment method using an annular air curtain.Through numerical simulat...The low-oxygen environment restricts the exploitation of mineral resources on plateaus and affects miner’s safety.This paper proposes an oxygen-enrichment method using an annular air curtain.Through numerical simulation and experiments,it was confirmed that the proposed method improves the breathing environment in the single-head roadway of a plateau mine.Computational fluid dynamics(CFD)was used to investigate the oxygen-enriching effect and oxygen spatial distribution regularities after using the proposed oxygen-enrichment method in the single-head roadway of a plateau mine.The reliability of the CFD model was confirmed by experiment.Orthogonal testing was conducted to investigate the influence degree and optimal level combination of factors influencing oxygen enrichment.The results demonstrate that the annular air curtain effectively prevented oxygen loss,thus forming a local oxygen-rich space and improving the effective utilization rate of oxygen.Oxygen supply concentration and velocity are positively correlated with the oronasal oxygen mass fraction through a linear function,while the air curtain outlet wind velocity is negatively correlated with the oronasal oxygen mass fraction through a linear function.The annular air curtain diameter and oronasal oxygen mass fraction do not have an obvious functional relationship.When the annular air curtain diameter was greater than 0.9 m,the oronasal oxygen mass fraction was stable at approximately 25.30%.The influencing factors of the novel oxygen-enrichment method are,in descending order,as follows:oxygen supply concentration,annular air curtain diameter,air curtain outlet wind velocity,and oxygen supply velocity.The optimal level combination is oxygen supply concentration of 100%,oxygen supply velocity of 11 m/s,air curtain outlet wind velocity of 1.5 m/s,and annular air curtain diameter of 0.9 m.展开更多
基金supported financially by National Key Research and Development Program of China(2017YFB0103001)。
文摘The performance and operation stability of proton exchange membrane fuel cells(PEMFCs)are closely related to the transportation of reactants and water management in the membrane electrode assembly(MEA)and flow field.In this paper,a new three-dimensional wave parallel flow field(WPFF)in cathode was designed and analyzed throughout simulation studies and an experimental method.The experimental results show that the performance of PEMFC with WPFF outperforms that of PEMFC with straight parallel flow field(SPFF).Specifically,the peak power density increased by 13.45%for the PEMFC with WPFF as opposed to PEMFC with SPFF.In addition,the flow field with area of 11.56 cm^(2) was formed by the assembly of transparent end plate used for cathode and the traditional graphite plate used for anode.To understand the mechanism of the novel flow field improving the performance of PEMFC,a model of PEMFC was proposed based on the geometry,operating conditions and MEA parameters.The thickness of gas diffusion layers(GDL),catalytic layers(CL)and proton exchange membrane were measured by scanning electron microscope.The simulation result shows that compared with SPFF,the WPFF based PEMFC promote the oxygen transfer from flow channel to the surface of CL through GDL,and it was beneficial to remove the liquid water in the flow channel and the MEA.
基金Supported by grants from the National Science Foundation of China(31072053,30671516)Natural Science Foundation of Hunan Province,China(11JJ2014)Specialized Research Fund for the Doctoral Program of Higher Education,Ministry of Education,China(20104320110001)
文摘[Objective]This study aimed to research the effect of metallothionein on cell cycle,apoptosis rate and subsets distribution of lymphocytes in peripheral blood of dairy cows under heat stress,so as to perfect the regulative mechanism researches of MT to anti-heat stress.[Method]Twenty lactating Chinese Holstein cows were randomly divided into four groups(A,B,C and D),and injected with 0,4.0,8.0 and 12.0 mg Zn-metallothionein,respectively by intravenous route.Blood samples were collected at 1st,16th,31st,46thand 61stday,and the dynamic changes of cell cycle,apoptosis rate and subsets distribution of lymphocytes were determined.[Result]The apoptosis rate of cells in group B and C was lower than those in group A by 26.63%(P>0.05)and 24.84%(P>0.05)respectively.The number of cells in the G0/G1phage in trial groups was increased and the number of cells in the S and G2/M phages tended to decrease,but there were no significant differences(P>0.05).The number of CD3+T cell in three trial groups was greater than those in group A by 7.02%(P>0.05),5.45%(P>0.05)and 3.85%(P>0.05)respectively,while the number of CD4+T cell in trial groups was higher than those in control group by31.04%(P<0.05),35.68%(P<0.05)and 39.34%(P<0.05)respectively.The number of CD8+T cell and the levels of CD4+/CD8+in trial groups were increased observably,but significant difference(P<0.05)was observed in the levels of CD4+/CD8+between groups A and C only.It demonstrated that exogenous Zn-metallothionein can decrease apoptosis rate,improve cell cycle and regulate subsets distribution of lymphocytes in dairy cattle in a dose-dependent manner.[Conclusion]This study will provide scientific basis for safe utilization of MT in dairy industry.
基金This study was supported by the Scientific Research Project of Guangzhou, Guangdong Province, China (No. 20184010458).
文摘The aim is to explore the predictive value of salivary bacteria for the presence of esophageal squamous cell carcinoma (ESCC). Saliva samples were obtained from 178 patients with ESCC and 101 healthy controls, and allocated to screening and verification cohorts, respectively. In the screening phase, after saliva DNA was extracted, 16S rRNA V4 regions of salivary bacteria were amplified by polymerase chain reaction (PCR) with high-throughput sequencing. Highly expressed target bacteria were screened by Operational Taxonomic Units clustering, species annotation and microbial diversity assessment. In the verification phase, the expression levels of target bacteria identified in the screening phase were verified by absolute quantitative PCR (Q-PCR). Receiver operating characteristic (ROC) curves were plotted to investigate the predictive value of target salivary bacteria. LEfSe analysis revealed higher proportions of Fusobacterium, Streptococcus and Porphyromonas, and Q-PCR assay showed significantly higher numbers of Streptococcus salivarius, Fusobacterium nucleatum and Porphyromonas gingivalis in patients with ESCC, when compared with healthy controls (all P < 0.05). The areas under the ROC curves for Streptococcus salivarius, Fusobacterium nucleatum, Porphyromonas gingivalis and the combination of the three bacteria for predicting patients with ESCC were 69%, 56.5%, 61.8% and 76.4%, respectively. The sensitivities corresponding to cutoff value were 69.3%, 22.7%, 35.2% and 86.4%, respectively, and the matched specificity were 78.4%, 96.1%, 90.2% and 58.8%, respectively. These highly expressed Streptococcus salivarius, Fusobacterium nucleatum and Porphyromonas gingivalis in the saliva, alone or in combination, indicate their predictive value for ESCC.
基金supported by the Natural Science Foundation of China (81971520,32141004,82171775)Project (RDGS2022-05) supported by Peking University People's Hospital Scientific Research Development FundsBeijing Children's Hospital Young Investigator Program.
文摘Dear Editor,Previous studies have proved that regulatory T cell(Treg)insufficiency contributed to the development of autoimmune conditions including systemic lupus erythematosus(SLE).Conventional immunosuppressive treatment was reported to downregulate beneficial Tregs together with pathogenic effector immune cells,which may impede a rapid achievement of optimal therapeutic effects.
基金supported by the National Natural Science Foundation of China(22234005,21974070,22222407,22176099)the Natural Science Foundation of Jiangsu Province(BK20192008)the State Key Laboratory of Analytical Chemistry for Life Science(SKLACLS2220)。
文摘The content of biothiols in cells is highly associated with the occurrence and development of several diseases.However,due to their active chemical properties,thiol-contained molecules are normally volatile during the detection process,rendering precise analysis of intracellular biothiols challenging.In this study,5,5’-dithiobis-(2-nitrobenzoic acid)(DTNB)is covalently modified on the surface of gold nanorods(AuNRs),constructing sensing substrates for in situ Raman imaging analysis of biothiols in cells.Au NRs are able to serve as ideal surface-enhanced Raman scattering substrates,and thus Raman signals of DTNB are greatly amplified by AuNRs.Meanwhile,the disulfide bond of DTNB can be broken by thiols,thereby releasing part of DTNB from the surface of AuNRs.As a result,three kinds of main biothiols are sensitively quantified with DTNB-modified AuNRs according to the variation of Raman signals,and DTNB-modified Au NRs exhibit far better analytical performance than a commercial probe.In addition,the sensing substrates can be readily delivered to cytoplasm with the transmembrane of Au NRs,and are capable of responding to biothiols in cells.Notably,the Raman approach is established by the breaking of chemical bonds rather than the aggregation of substrates,which is more inclined to analyze intracellular biothiols with a desirable spatial resolution.Therefore,fluctuation of biothiols in glioma cells is evidently observed via Raman imaging.Overall,this work provides an alternative strategy for designing Raman sensors to visualize active molecules in cells.
基金supports of the National Natural Science Foundation of China(No.52274247)the Postgraduate Scientific Research Innovation Project of Hunan Province(No.CX20220196).
文摘The low-oxygen environment restricts the exploitation of mineral resources on plateaus and affects miner’s safety.This paper proposes an oxygen-enrichment method using an annular air curtain.Through numerical simulation and experiments,it was confirmed that the proposed method improves the breathing environment in the single-head roadway of a plateau mine.Computational fluid dynamics(CFD)was used to investigate the oxygen-enriching effect and oxygen spatial distribution regularities after using the proposed oxygen-enrichment method in the single-head roadway of a plateau mine.The reliability of the CFD model was confirmed by experiment.Orthogonal testing was conducted to investigate the influence degree and optimal level combination of factors influencing oxygen enrichment.The results demonstrate that the annular air curtain effectively prevented oxygen loss,thus forming a local oxygen-rich space and improving the effective utilization rate of oxygen.Oxygen supply concentration and velocity are positively correlated with the oronasal oxygen mass fraction through a linear function,while the air curtain outlet wind velocity is negatively correlated with the oronasal oxygen mass fraction through a linear function.The annular air curtain diameter and oronasal oxygen mass fraction do not have an obvious functional relationship.When the annular air curtain diameter was greater than 0.9 m,the oronasal oxygen mass fraction was stable at approximately 25.30%.The influencing factors of the novel oxygen-enrichment method are,in descending order,as follows:oxygen supply concentration,annular air curtain diameter,air curtain outlet wind velocity,and oxygen supply velocity.The optimal level combination is oxygen supply concentration of 100%,oxygen supply velocity of 11 m/s,air curtain outlet wind velocity of 1.5 m/s,and annular air curtain diameter of 0.9 m.