The photoreduction of CO_(2)into CH_(4)with simultaneous high activity and selectivity is a promising strategy to increase energy supply and alleviate global warming.However,the absence of the active sites that is res...The photoreduction of CO_(2)into CH_(4)with simultaneous high activity and selectivity is a promising strategy to increase energy supply and alleviate global warming.However,the absence of the active sites that is responsible for the adsorption and activation of CO_(2)and the generation of CO and H2via side reactions often lead to poor efficiency and low selectivity of the catalyst.Herein,Cu,Pd,and PdCu metal clusters cocatalyst-anchored defective TiO_(2)nanotubes(Cu/TiO_(2)-SBO,Pd/TiO_(2)-SBO,and Pd1Cu1/TiO_(2)-SBO)were designed via a simple solution impregnation reduction and applied for photocatalytic conversion of CO_(2)to CH_(4).The Pd1Cu1/TiO_(2)-SBO photocatalyst exhibits excellent catalytic performance among the other catalysts for photoreduction of CO_(2)into CH_(4).More interestingly,the product selectivity of CH_(4)reaches up to 100%with a rate of 25μmol g^(-1)h^(-1).In-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and density functional theory(DFT)simulations indicate that the main reasons for the high selectivity of CH_(4)are attributed to the PdCu alloy and oxygen vacancies,which jointly enhance the photoinduced carrier separation and lower energy barriers of key intermediates.Moreover,due to the tunable d-band center of the Cu site in the PdCu alloy,the generated intermediates can be well prevented from poisoning and promoted to participate in further reactions.Hopefully,the current study will provide insight into the development of new,highly selective photocatalysts for the visible light-catalytic reduction of CO_(2)into CH_(4).展开更多
Considering the components produced by high pressure die casting(HPDC)process usually with ultra-large sizes and complex morphologies,high temperature solid solution treatment is not a suitable method to further impro...Considering the components produced by high pressure die casting(HPDC)process usually with ultra-large sizes and complex morphologies,high temperature solid solution treatment is not a suitable method to further improve their mechanical properties.In this study,two-stage aging treatment with different pre-aging times was designed and employed to further improve the mechanical properties of HPDC Al8SiMgCuZn alloy.The characteristics of precipitates were evaluated by a transmission electron microscope(TEM),and the precipitation strengthening mechanism was discussed.The results reveal that the strengthening is mainly contributed by the precipitation ofβ″phase after two-stage aging,and the number density and size of the precipitates are significantly depended on the pre-aging time.The number density of precipitates is increased with the pre-aging time prolonged from 0 h to 4 h,and then decreases with the further increase of pre-aging time from 4 h to 6 h.The precipitates with the highest density and smallest size are observed after pre-aging for 4 h.After pre-aged at 100℃for 4 h and then artificial aged at 200℃for 30 min,the yield strength of 207 MPa,ultimate tensile strength of 325 MPa and elongation of 7.6%are achieved.展开更多
To date,there is still a lack of a comprehensive explanation for caged dynamics which is regarded as one of the intricate dynamic behaviors in amorphous alloys.This study focuses on Pd_(82)Si_(18)as the research objec...To date,there is still a lack of a comprehensive explanation for caged dynamics which is regarded as one of the intricate dynamic behaviors in amorphous alloys.This study focuses on Pd_(82)Si_(18)as the research object to further elucidate the underlying mechanism of caged dynamics from multiple perspectives,including the cage's lifetime,atomic local environment,and atomic potential energy.The results reveal that Si atoms exhibit a pronounced cage effect due to the hindrance of Pd atoms,resulting in an anomalous peak in the non-Gaussian parameters.An in-depth investigation was conducted on the caged dynamics differences between fast and slow Si atoms.In comparison to fast Si atoms,slow Si atoms were surrounded by more Pd atoms and occupied lower potential energy states,resulting in smaller diffusion displacements for the slow Si atoms.Concurrently,slow Si atoms tend to be in the centers of smaller clusters with coordination numbers of 9 and 10.During the isothermal relaxation process,clusters with coordination numbers 9 and 10 have longer lifetimes,suggesting that the escape of slow Si atoms from their cages is more challenging.The findings mentioned above hold significant implications for understanding the caged dynamics.展开更多
背景众多证据表明免疫逃逸在肿瘤形成过程中扮演重要角色,慢性萎缩性胃炎(chronic atrophic gastritis,CAG)是胃癌的癌前疾病.安胃汤被发现可改善CAG临床症状及病理表现,实现CAG的逆转,该作用是否与免疫逃逸机制相关有待进一步研究.目...背景众多证据表明免疫逃逸在肿瘤形成过程中扮演重要角色,慢性萎缩性胃炎(chronic atrophic gastritis,CAG)是胃癌的癌前疾病.安胃汤被发现可改善CAG临床症状及病理表现,实现CAG的逆转,该作用是否与免疫逃逸机制相关有待进一步研究.目的从细胞免疫逃逸角度,探讨程序性死亡受体-1(programmed cell death protein 1,PD-1)/程序性死亡受体配体-1(programmed cell death ligand 1,PD-L1)信号轴与安胃汤对CAG模型大鼠疗效之间的关系.方法采用1-甲基-3-硝基-1-亚硝基胍(1-Methyl-3-nitro-1-nitrosoguanidine,MNNG)慢性萎缩性胃炎大鼠模型,应用不同剂量安胃汤及维酶素片进行干预;HE染色观察安胃汤对CAG模型大鼠胃黏膜炎症细胞浸润及组织形态改变的影响;免疫组化检测CAG模型大鼠胃黏膜组织PD-1、PD-L1蛋白表达;ELISA检测血清CD4^(+)、CD8^(+)水平变化;qPCR检测CAG模型大鼠胃黏膜PD-1mRNA、PD-L1mRNA表达;Western-blot检测CAG模型大鼠胃黏膜组织PD-1、PD-L1蛋白表达.结果免疫组化结果示:与模型组和维酶素组比较,安胃汤高、低剂量组PD-L1表达均较低(P<0.01,P<0.05).ELISA实验结果示:与模型组比较,安胃汤高剂量组CD4^(+)表达及CD4^(+)/CD8^(+)比值升高(P<0.01,P<0.05),安胃汤各组和维酶素组CD8^(+)表达降低(P<0.01);与维酶素组比较,安胃汤高剂量组CD8^(+)表达降低(P<0.05).qPCR实验结果显示:与模型组比较,安胃汤高剂量组和维酶素组PD-1mRNA表达下降(P<0.01),安胃汤高、中剂量组PD-L1mRNA表达下降(P<0.01,P<0.05).Western-blot实验结果显示:与模型组比较,安胃汤高、中剂量组PD-1/Actin,PD-L1/Actin表达下降(P<0.01,P<0.05).结论安胃汤抗CAG作用可能与抑制PD-1/PD-L1信号通路诱导的细胞免疫逃逸有关.展开更多
目的探讨肉瘤样肾细胞癌组织中PD-L1的表达及肿瘤内微血管密度情况,为肉瘤样肾细胞癌免疫治疗及靶向治疗方案的选择提供理论依据。方法通过免疫组化法检测PD-L1、CD31及CD34在16例肉瘤样肾细胞癌(癌成分均为透明细胞肾细胞癌)中的表达,...目的探讨肉瘤样肾细胞癌组织中PD-L1的表达及肿瘤内微血管密度情况,为肉瘤样肾细胞癌免疫治疗及靶向治疗方案的选择提供理论依据。方法通过免疫组化法检测PD-L1、CD31及CD34在16例肉瘤样肾细胞癌(癌成分均为透明细胞肾细胞癌)中的表达,并评估肿瘤微血管密度。结果16例肿瘤中CD31和CD34免疫组化染色显示,肉瘤样肾细胞癌区域微血管密度明显高于不伴肉瘤样分化的区域,微血管密度计数分别为68.6±25.8 vs 38.7±16.0(t=3.931,P=0.0005)和69.5±28.1 vs 40.1±18.4(t=3.506,P=0.0015),差异有统计学意义。肉瘤样区域PD-L1表达水平高于非肉瘤样区域,CPS分别为34.7±26.9和25.9±27.6,但差异无统计学意义。结论在肉瘤样肾细胞癌中,肉瘤样区域微血管密度和PD-L1表达水平明显高于非肉瘤样区域,提示靶向治疗联合免疫治疗可能为此类肿瘤提供一种有效的治疗方法。展开更多
基金the financial support from the Program for Innovative Research Team in University of Henan Province(21IRTSTHN009)Science and Technology Fund of Henan Province(225200810051)Natural Science Foundation of Henan Province(222300420406)。
文摘The photoreduction of CO_(2)into CH_(4)with simultaneous high activity and selectivity is a promising strategy to increase energy supply and alleviate global warming.However,the absence of the active sites that is responsible for the adsorption and activation of CO_(2)and the generation of CO and H2via side reactions often lead to poor efficiency and low selectivity of the catalyst.Herein,Cu,Pd,and PdCu metal clusters cocatalyst-anchored defective TiO_(2)nanotubes(Cu/TiO_(2)-SBO,Pd/TiO_(2)-SBO,and Pd1Cu1/TiO_(2)-SBO)were designed via a simple solution impregnation reduction and applied for photocatalytic conversion of CO_(2)to CH_(4).The Pd1Cu1/TiO_(2)-SBO photocatalyst exhibits excellent catalytic performance among the other catalysts for photoreduction of CO_(2)into CH_(4).More interestingly,the product selectivity of CH_(4)reaches up to 100%with a rate of 25μmol g^(-1)h^(-1).In-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and density functional theory(DFT)simulations indicate that the main reasons for the high selectivity of CH_(4)are attributed to the PdCu alloy and oxygen vacancies,which jointly enhance the photoinduced carrier separation and lower energy barriers of key intermediates.Moreover,due to the tunable d-band center of the Cu site in the PdCu alloy,the generated intermediates can be well prevented from poisoning and promoted to participate in further reactions.Hopefully,the current study will provide insight into the development of new,highly selective photocatalysts for the visible light-catalytic reduction of CO_(2)into CH_(4).
基金financially supported by the Natural Science Foundation of Guangdong Province(Nos.2021A151510042,2021A1515011728)the China Postdoctoral Science Foundation(2022M711190)+1 种基金the National Natural Science Foundation of China(No.51875211)the Key Area Research and Development Program of Guangdong Province(No.2020B010186002)。
文摘Considering the components produced by high pressure die casting(HPDC)process usually with ultra-large sizes and complex morphologies,high temperature solid solution treatment is not a suitable method to further improve their mechanical properties.In this study,two-stage aging treatment with different pre-aging times was designed and employed to further improve the mechanical properties of HPDC Al8SiMgCuZn alloy.The characteristics of precipitates were evaluated by a transmission electron microscope(TEM),and the precipitation strengthening mechanism was discussed.The results reveal that the strengthening is mainly contributed by the precipitation ofβ″phase after two-stage aging,and the number density and size of the precipitates are significantly depended on the pre-aging time.The number density of precipitates is increased with the pre-aging time prolonged from 0 h to 4 h,and then decreases with the further increase of pre-aging time from 4 h to 6 h.The precipitates with the highest density and smallest size are observed after pre-aging for 4 h.After pre-aged at 100℃for 4 h and then artificial aged at 200℃for 30 min,the yield strength of 207 MPa,ultimate tensile strength of 325 MPa and elongation of 7.6%are achieved.
基金Project supported by the National Natural Science Foundation of China (Grant No.51701071)the Natural Science Foundation of Hunan Province,China (Grant Nos.2022JJ50115 and 2021JJ30179)the Research Foundation of the Education Bureau of Hunan Province,China (Grant No.22A0522)。
文摘To date,there is still a lack of a comprehensive explanation for caged dynamics which is regarded as one of the intricate dynamic behaviors in amorphous alloys.This study focuses on Pd_(82)Si_(18)as the research object to further elucidate the underlying mechanism of caged dynamics from multiple perspectives,including the cage's lifetime,atomic local environment,and atomic potential energy.The results reveal that Si atoms exhibit a pronounced cage effect due to the hindrance of Pd atoms,resulting in an anomalous peak in the non-Gaussian parameters.An in-depth investigation was conducted on the caged dynamics differences between fast and slow Si atoms.In comparison to fast Si atoms,slow Si atoms were surrounded by more Pd atoms and occupied lower potential energy states,resulting in smaller diffusion displacements for the slow Si atoms.Concurrently,slow Si atoms tend to be in the centers of smaller clusters with coordination numbers of 9 and 10.During the isothermal relaxation process,clusters with coordination numbers 9 and 10 have longer lifetimes,suggesting that the escape of slow Si atoms from their cages is more challenging.The findings mentioned above hold significant implications for understanding the caged dynamics.
文摘背景众多证据表明免疫逃逸在肿瘤形成过程中扮演重要角色,慢性萎缩性胃炎(chronic atrophic gastritis,CAG)是胃癌的癌前疾病.安胃汤被发现可改善CAG临床症状及病理表现,实现CAG的逆转,该作用是否与免疫逃逸机制相关有待进一步研究.目的从细胞免疫逃逸角度,探讨程序性死亡受体-1(programmed cell death protein 1,PD-1)/程序性死亡受体配体-1(programmed cell death ligand 1,PD-L1)信号轴与安胃汤对CAG模型大鼠疗效之间的关系.方法采用1-甲基-3-硝基-1-亚硝基胍(1-Methyl-3-nitro-1-nitrosoguanidine,MNNG)慢性萎缩性胃炎大鼠模型,应用不同剂量安胃汤及维酶素片进行干预;HE染色观察安胃汤对CAG模型大鼠胃黏膜炎症细胞浸润及组织形态改变的影响;免疫组化检测CAG模型大鼠胃黏膜组织PD-1、PD-L1蛋白表达;ELISA检测血清CD4^(+)、CD8^(+)水平变化;qPCR检测CAG模型大鼠胃黏膜PD-1mRNA、PD-L1mRNA表达;Western-blot检测CAG模型大鼠胃黏膜组织PD-1、PD-L1蛋白表达.结果免疫组化结果示:与模型组和维酶素组比较,安胃汤高、低剂量组PD-L1表达均较低(P<0.01,P<0.05).ELISA实验结果示:与模型组比较,安胃汤高剂量组CD4^(+)表达及CD4^(+)/CD8^(+)比值升高(P<0.01,P<0.05),安胃汤各组和维酶素组CD8^(+)表达降低(P<0.01);与维酶素组比较,安胃汤高剂量组CD8^(+)表达降低(P<0.05).qPCR实验结果显示:与模型组比较,安胃汤高剂量组和维酶素组PD-1mRNA表达下降(P<0.01),安胃汤高、中剂量组PD-L1mRNA表达下降(P<0.01,P<0.05).Western-blot实验结果显示:与模型组比较,安胃汤高、中剂量组PD-1/Actin,PD-L1/Actin表达下降(P<0.01,P<0.05).结论安胃汤抗CAG作用可能与抑制PD-1/PD-L1信号通路诱导的细胞免疫逃逸有关.
文摘目的探讨肉瘤样肾细胞癌组织中PD-L1的表达及肿瘤内微血管密度情况,为肉瘤样肾细胞癌免疫治疗及靶向治疗方案的选择提供理论依据。方法通过免疫组化法检测PD-L1、CD31及CD34在16例肉瘤样肾细胞癌(癌成分均为透明细胞肾细胞癌)中的表达,并评估肿瘤微血管密度。结果16例肿瘤中CD31和CD34免疫组化染色显示,肉瘤样肾细胞癌区域微血管密度明显高于不伴肉瘤样分化的区域,微血管密度计数分别为68.6±25.8 vs 38.7±16.0(t=3.931,P=0.0005)和69.5±28.1 vs 40.1±18.4(t=3.506,P=0.0015),差异有统计学意义。肉瘤样区域PD-L1表达水平高于非肉瘤样区域,CPS分别为34.7±26.9和25.9±27.6,但差异无统计学意义。结论在肉瘤样肾细胞癌中,肉瘤样区域微血管密度和PD-L1表达水平明显高于非肉瘤样区域,提示靶向治疗联合免疫治疗可能为此类肿瘤提供一种有效的治疗方法。
