Z-scheme photocatalytic system has been regarded as a popular field of research in photoelectrochemical(PEC)water splitting.Among the many obstacles facing a Z-scheme photocatalytic system,the analysis methods of inte...Z-scheme photocatalytic system has been regarded as a popular field of research in photoelectrochemical(PEC)water splitting.Among the many obstacles facing a Z-scheme photocatalytic system,the analysis methods of interfacial Z-scheme charge transfer still remain a significant challenge.Hence,in this study,CdS/Ti-Fe_(2)O_(3)heterojunction photoanodes are elaborately designed to explore the charge-transfer behavior in PEC water splitting.In this study,photophysical measurements,including the Kelvin probe measurement,surface photovoltage spectroscopy(SPV),and transient photovoltage spectroscopy(TPV),are used to monitor the migration behavior of photogenerated charges at the interface electric field of CdS/Ti-Fe_(2)O_(3)Z-scheme heterojunction photoanodes.The Kelvin probe and SPV measurements demonstrate that CdS/Ti-Fe_(2)O_(3)interfacial driving force favors the rapid transfer of photoexcited electrons to CdS.The double-beam strategy based on TPV indicates that more electrons of Ti-Fe_(2)O_(3)are combined with the holes of CdS owing to the intensive interface electric field.The results of these measurements successfully prove the Z-scheme migration mechanism of CdS/Ti-Fe_(2)O_(3)photoanodes.Benefiting from the desirable charge transfer at the interface electric field,CdS/Ti-Fe_(2)O_(3)photoanodes exhibit superior photocatalytic oxygen evolution reaction performance compared with that of pure Ti-Fe_(2)O_(3).The photocurrent density of the 25CdS/Ti-Fe_(2)O_(3)photoanode reaches 1.94 mA/cm^(2) at 1.23 V versus reversible hydrogen electrode without excess cocatalyst,and it is two times higher than that of pure Ti-Fe_(2)O_(3)photoanode.Therefore,an outstanding strategy is provided in this study to prove the Z-scheme charge-transfer mechanism of photocatalytic systems in PEC water splitting.展开更多
Pure Cu nanowires as catalyst were prepared by electrochemical deposition and were used in CO2 hydrogenation to methanol.The active sites of the Cu based catalyst were discussed.The performance and structural developm...Pure Cu nanowires as catalyst were prepared by electrochemical deposition and were used in CO2 hydrogenation to methanol.The active sites of the Cu based catalyst were discussed.The performance and structural development of the catalyst were observed during CO2 hydrogenation.A mechanism for the deactivation of the catalyst was discussed.The key factors that affect the deactivation of the catalyst were found.Cu nanowire sample was characterized by SEM,EDS,XRD,and BET.The results show that Cu nanowires have very high sintering resistance and catalytic stability.This helps to develop high performance catalysts.The changes in the grain size,SEM morphology and catalytic properties of the sample during CO2 hydrogenation show that the migration of the Cu atoms on the surface of the Cu nanowires can occur.Continuous migration of Cu atoms and sintering of Cu grains can lead to flow blockage in gas channels.The gas channel flow blockage or the sintering of Cu grains can lead to deactivation of the catalyst.However,the shape of catalytic performance curve indicates that the main reason for the deactivation of the catalyst is the gas channel flow blockage.展开更多
Although CO_(2)photoreduction is a promising method for solar‐to‐fuel conversion,it suffers from low charge transfer efficiency of the photocatalysts.To improve the CO_(2)photoreduction performance,introduction of e...Although CO_(2)photoreduction is a promising method for solar‐to‐fuel conversion,it suffers from low charge transfer efficiency of the photocatalysts.To improve the CO_(2)photoreduction performance,introduction of electron‐accumulated materials on the photocatalyst surface is considered an effective method.In this study,the Bi_(19)S_(27)Br_(3)/BiOBr composites were designed and synthesized.The Bi19S27Br3 nanorod in this photocatalytic system acts as an electron‐accumulated active site for extracting the photogenerated electrons on the BiOBr surface and for effectively activating the CO2 molecules.As a result,Bi_(19)S_(27)Br_(3)/BiOBr composites exhibit the higher charge carrier transfer efficiency and further improves the CO_(2)photoreduction performance relative to that of pure Bi_(19)S_(27)Br_(3)and BiOBr.The rate of CO formation using Bi_(19)S_(27)Br_(3)/BiOBr‐5 is about 8.74 and 2.40 times that using Bi_(19)S_(27)Br_(3)and BiOBr,respectively.This work provides new insights for the application of Bi_(19)S_(27)Br_(3)as an electron‐accumulating site for achieving high photocatalytic CO2 reduction performance in the future.展开更多
Objective: Drug-resistance and metastasis are major reasons for the high mortality of ovarian cancer(OC) patients. Cyclooxygenase-2(COX-2) plays a critical role in OC development. This study was designed to evaluate t...Objective: Drug-resistance and metastasis are major reasons for the high mortality of ovarian cancer(OC) patients. Cyclooxygenase-2(COX-2) plays a critical role in OC development. This study was designed to evaluate the effects of COX-2 on migration and cisplatin(cis-dichloro diammine platinum, CDDP) resistance of OC cells and explore its related mechanisms. Methods: Cell counting kit-8(CCK-8) assay was used to detect the cytotoxicity effects of celecoxib(CXB) and CDDP on SKOV3 and ES2 cells. The effect of COX-2 on migration was evaluated via the healing test. Western blot and real-time quantitative polymerase chain reaction(q PCR) were used to analyze E-cadherin, vimentin, Snail, and Slug levels. Results: COX-2 promoted drug-resistance and cell migration. CXB inhibited these effects. The combination of CDDP and CXB increased tumor cell sensitivity, reduced the amount of CDDP required, and shortened treatment administration time. COX-2 upregulation increased the expression of Snail and Slug, resulting in E-cadherin expression downregulation and vimentin upregulation. Conclusions: COX-2 promotes cancer cell migration and CDDP resistance and may serve as a potential target for curing OC.展开更多
AIM： To study the effect of nicotine on the migration and invasion of human esophageal squamous carcinoma cells and to investigate whether nimesulide can inhibit the effect of nicotine.METHODS： The esophageal squamo...AIM： To study the effect of nicotine on the migration and invasion of human esophageal squamous carcinoma cells and to investigate whether nimesulide can inhibit the effect of nicotine.METHODS： The esophageal squamous carcinoma cell line （TE-13） was treated with different concentrations of nicotine （100 μg/mL and 200 μg/mL） or 200 μg/mL nicotine plus 100 μmol/L nimesulide. Cell migration and invasion were measured using migration and invasion chamber systems. COX-2 expression was determined by Western blotting. Matrix metalloproteinase-2 （MMP-2） was analyzed by zymography and ELISA.RESULTS： Nicotine （100 μg/mL, 200 μg/mL） enhanced TE-13 cells migration and invasion, and increased the protein expression of COX-2 and the activity of MMP-2. Nicotine （200 μ/mL） stimulated TE-13 cells migration and invasion which were partly blocked by nimesulide. This was associated with decreased protein expression of COX-2 and decreased activity and protein expression of MMP-2. CONCLUSION： Nicotine enhances the migration and invasion of the esophageal squamous carcinoma cell line, and nimesulide partly blocks the effect ofnicotine-enhanced esophageal squamous carcinoma cell migration and invasion.展开更多
Breast cancer is one of the most common female malignant tumors in the world. Although many therapeutic methods for HER-2 positive breast cancer have been developed, the drug resistance and distant metastasis still re...Breast cancer is one of the most common female malignant tumors in the world. Although many therapeutic methods for HER-2 positive breast cancer have been developed, the drug resistance and distant metastasis still remain. Tetraarsenic oxide（As_4O_6） has been demonstrated with an anticancer effect on squamous cell carcinoma and cervical cancer. However, there is no report about the relationship between As_4O_6 and HER-2 positive breast cancer. In the present study, we detected the inhibitory efficacy and mechanism of As_4O_6 on the migration and invasion of SKBR3 breast cancer cells using molecular biological methods. The wound-healing assay, matrigel migration assay, transwell invasion assay and cell adhesion assay were used to assess the migration, invasion and adhesion of SKBR3 cells intervened by As_4O_6. Meanwhile, the reverse transcription-PCR and western blotting were performed to investigate the mechanism of As_4O_6 on the migration and invasion of SKBR3 breast cancer cells. The results demonstrated that As_4O_6 could efficiently inhibit the migration and invasion of SKBR3 cells, the HER-2 positive breast cancer cells, and the adhesion of SKBR3 cells was decreased after As_4O_6 treatment. The mechanism revealed that As_4O_6 anticancer efficacy was related to HER-2/EGFR pathways. As_4O_6 exerted its inhibitory effects on migration and invasion in HER-2 positive breast cancer cells by regulating the factors（EGFR, HER-2, Akt, MMP-9） in HER2/ EGFR signaling pathway and other key molecules. In conclusion, the present study indicated that As_4O_6 inhibited the invasion and migration process of HER-2 positive breast cancer SKBR3 cells by negatively regulating the HER-2/EGFR-mediated signaling pathway. These data provided evidence that As_4O_6 might serve as potential anti-metastasis drug for clinical treatment of breast cancer.展开更多
文摘Z-scheme photocatalytic system has been regarded as a popular field of research in photoelectrochemical(PEC)water splitting.Among the many obstacles facing a Z-scheme photocatalytic system,the analysis methods of interfacial Z-scheme charge transfer still remain a significant challenge.Hence,in this study,CdS/Ti-Fe_(2)O_(3)heterojunction photoanodes are elaborately designed to explore the charge-transfer behavior in PEC water splitting.In this study,photophysical measurements,including the Kelvin probe measurement,surface photovoltage spectroscopy(SPV),and transient photovoltage spectroscopy(TPV),are used to monitor the migration behavior of photogenerated charges at the interface electric field of CdS/Ti-Fe_(2)O_(3)Z-scheme heterojunction photoanodes.The Kelvin probe and SPV measurements demonstrate that CdS/Ti-Fe_(2)O_(3)interfacial driving force favors the rapid transfer of photoexcited electrons to CdS.The double-beam strategy based on TPV indicates that more electrons of Ti-Fe_(2)O_(3)are combined with the holes of CdS owing to the intensive interface electric field.The results of these measurements successfully prove the Z-scheme migration mechanism of CdS/Ti-Fe_(2)O_(3)photoanodes.Benefiting from the desirable charge transfer at the interface electric field,CdS/Ti-Fe_(2)O_(3)photoanodes exhibit superior photocatalytic oxygen evolution reaction performance compared with that of pure Ti-Fe_(2)O_(3).The photocurrent density of the 25CdS/Ti-Fe_(2)O_(3)photoanode reaches 1.94 mA/cm^(2) at 1.23 V versus reversible hydrogen electrode without excess cocatalyst,and it is two times higher than that of pure Ti-Fe_(2)O_(3)photoanode.Therefore,an outstanding strategy is provided in this study to prove the Z-scheme charge-transfer mechanism of photocatalytic systems in PEC water splitting.
基金Project(51074205)supported by the National Natural Science Foundation of China
文摘Pure Cu nanowires as catalyst were prepared by electrochemical deposition and were used in CO2 hydrogenation to methanol.The active sites of the Cu based catalyst were discussed.The performance and structural development of the catalyst were observed during CO2 hydrogenation.A mechanism for the deactivation of the catalyst was discussed.The key factors that affect the deactivation of the catalyst were found.Cu nanowire sample was characterized by SEM,EDS,XRD,and BET.The results show that Cu nanowires have very high sintering resistance and catalytic stability.This helps to develop high performance catalysts.The changes in the grain size,SEM morphology and catalytic properties of the sample during CO2 hydrogenation show that the migration of the Cu atoms on the surface of the Cu nanowires can occur.Continuous migration of Cu atoms and sintering of Cu grains can lead to flow blockage in gas channels.The gas channel flow blockage or the sintering of Cu grains can lead to deactivation of the catalyst.However,the shape of catalytic performance curve indicates that the main reason for the deactivation of the catalyst is the gas channel flow blockage.
文摘Although CO_(2)photoreduction is a promising method for solar‐to‐fuel conversion,it suffers from low charge transfer efficiency of the photocatalysts.To improve the CO_(2)photoreduction performance,introduction of electron‐accumulated materials on the photocatalyst surface is considered an effective method.In this study,the Bi_(19)S_(27)Br_(3)/BiOBr composites were designed and synthesized.The Bi19S27Br3 nanorod in this photocatalytic system acts as an electron‐accumulated active site for extracting the photogenerated electrons on the BiOBr surface and for effectively activating the CO2 molecules.As a result,Bi_(19)S_(27)Br_(3)/BiOBr composites exhibit the higher charge carrier transfer efficiency and further improves the CO_(2)photoreduction performance relative to that of pure Bi_(19)S_(27)Br_(3)and BiOBr.The rate of CO formation using Bi_(19)S_(27)Br_(3)/BiOBr‐5 is about 8.74 and 2.40 times that using Bi_(19)S_(27)Br_(3)and BiOBr,respectively.This work provides new insights for the application of Bi_(19)S_(27)Br_(3)as an electron‐accumulating site for achieving high photocatalytic CO2 reduction performance in the future.
基金Project supported by the National Natural Science Foundation of China(No.81372777)。
文摘Objective: Drug-resistance and metastasis are major reasons for the high mortality of ovarian cancer(OC) patients. Cyclooxygenase-2(COX-2) plays a critical role in OC development. This study was designed to evaluate the effects of COX-2 on migration and cisplatin(cis-dichloro diammine platinum, CDDP) resistance of OC cells and explore its related mechanisms. Methods: Cell counting kit-8(CCK-8) assay was used to detect the cytotoxicity effects of celecoxib(CXB) and CDDP on SKOV3 and ES2 cells. The effect of COX-2 on migration was evaluated via the healing test. Western blot and real-time quantitative polymerase chain reaction(q PCR) were used to analyze E-cadherin, vimentin, Snail, and Slug levels. Results: COX-2 promoted drug-resistance and cell migration. CXB inhibited these effects. The combination of CDDP and CXB increased tumor cell sensitivity, reduced the amount of CDDP required, and shortened treatment administration time. COX-2 upregulation increased the expression of Snail and Slug, resulting in E-cadherin expression downregulation and vimentin upregulation. Conclusions: COX-2 promotes cancer cell migration and CDDP resistance and may serve as a potential target for curing OC.
基金Supported by Beijing Municipal Commission of Education, Science and Technology Program, No. KM200610025029Beijing Municipal Natural Science Foundation, No. 7072022
文摘AIM： To study the effect of nicotine on the migration and invasion of human esophageal squamous carcinoma cells and to investigate whether nimesulide can inhibit the effect of nicotine.METHODS： The esophageal squamous carcinoma cell line （TE-13） was treated with different concentrations of nicotine （100 μg/mL and 200 μg/mL） or 200 μg/mL nicotine plus 100 μmol/L nimesulide. Cell migration and invasion were measured using migration and invasion chamber systems. COX-2 expression was determined by Western blotting. Matrix metalloproteinase-2 （MMP-2） was analyzed by zymography and ELISA.RESULTS： Nicotine （100 μg/mL, 200 μg/mL） enhanced TE-13 cells migration and invasion, and increased the protein expression of COX-2 and the activity of MMP-2. Nicotine （200 μ/mL） stimulated TE-13 cells migration and invasion which were partly blocked by nimesulide. This was associated with decreased protein expression of COX-2 and decreased activity and protein expression of MMP-2. CONCLUSION： Nicotine enhances the migration and invasion of the esophageal squamous carcinoma cell line, and nimesulide partly blocks the effect ofnicotine-enhanced esophageal squamous carcinoma cell migration and invasion.
文摘Breast cancer is one of the most common female malignant tumors in the world. Although many therapeutic methods for HER-2 positive breast cancer have been developed, the drug resistance and distant metastasis still remain. Tetraarsenic oxide（As_4O_6） has been demonstrated with an anticancer effect on squamous cell carcinoma and cervical cancer. However, there is no report about the relationship between As_4O_6 and HER-2 positive breast cancer. In the present study, we detected the inhibitory efficacy and mechanism of As_4O_6 on the migration and invasion of SKBR3 breast cancer cells using molecular biological methods. The wound-healing assay, matrigel migration assay, transwell invasion assay and cell adhesion assay were used to assess the migration, invasion and adhesion of SKBR3 cells intervened by As_4O_6. Meanwhile, the reverse transcription-PCR and western blotting were performed to investigate the mechanism of As_4O_6 on the migration and invasion of SKBR3 breast cancer cells. The results demonstrated that As_4O_6 could efficiently inhibit the migration and invasion of SKBR3 cells, the HER-2 positive breast cancer cells, and the adhesion of SKBR3 cells was decreased after As_4O_6 treatment. The mechanism revealed that As_4O_6 anticancer efficacy was related to HER-2/EGFR pathways. As_4O_6 exerted its inhibitory effects on migration and invasion in HER-2 positive breast cancer cells by regulating the factors（EGFR, HER-2, Akt, MMP-9） in HER2/ EGFR signaling pathway and other key molecules. In conclusion, the present study indicated that As_4O_6 inhibited the invasion and migration process of HER-2 positive breast cancer SKBR3 cells by negatively regulating the HER-2/EGFR-mediated signaling pathway. These data provided evidence that As_4O_6 might serve as potential anti-metastasis drug for clinical treatment of breast cancer.
