We used density functional theory(DFT)calculations to study the influence of alkali earth metal element(AE)doping on the crystal structure and electronic band structure ofα-Si3N4.The diversity of atomic radii of alka...We used density functional theory(DFT)calculations to study the influence of alkali earth metal element(AE)doping on the crystal structure and electronic band structure ofα-Si3N4.The diversity of atomic radii of alkaline earth metal elements results in structural expansion when they were doped into theα-Si3N4 lattice.Formation energies of the doped structures indicate that dopants prefer to occupy the interstitial site under the nitrogen-deficient environment,while substitute Si under the nitrogen-rich environment,which provides a guide to synthesizingα-Si3N4 with different doping types by controlling nitrogen conditions.For electronic structures,energy levels of the dopants appear in the bottom of the conduction band or the top of the valence band or the forbidden band,which reduces the bandgap ofα-Si3N4.展开更多
A novel poly(methyl-methacrylate)/silica aerogel(PMMA/SA) dual-scale cellular foam was synthesized with internal mixing followed by the supercritical carbon dioxide foaming process.The effects of silica aerogel conten...A novel poly(methyl-methacrylate)/silica aerogel(PMMA/SA) dual-scale cellular foam was synthesized with internal mixing followed by the supercritical carbon dioxide foaming process.The effects of silica aerogel content on the microstructural and mechanical performance of the foams were investigated by SEM,TEM analysis,and mechanical tests.The experimental results suggest that the employment of silica aerogel granule as addictive can distinctly improve the morphological feature as well as the mechanical performance in comparison to neat PMMA foam by uniformizing cell size distribution,decreasing cell size and increasing cell density.And dual-scale cells including micrometric cells of 3-10 μm and nanometric cells of about 50 nm existed in the structure of foams resulting from the retained original framework structure of silica aerogel,which has not been described in other studies with the addition of various fillers.Furthermore,the mechanical strength was significantly elevated even with a small amount of silica aerogel resulting from the unique microstructure,decreased cell size and enhanced cell walls.The compressive strength was 18.12 MPa and the flexural strength was 18.90 MPa by adding 5wt% and 2wt% silica aerogel,respectively.These results demonstrate the potential to synthesize PMMA/SA dual-scale cellular foams to be used as structural materials with the advantages of low density and high strength.展开更多
目的探讨广州地区血透护士情绪智力在社会支持与主观幸福感间的中介效应,为血液透析中心科学管理护理人才提供实践指导。方法采用横断面研究方法,通过按比例分层抽样法,于2022年10月至2023年1月抽取在广州地区的800名血透护士为调查对象...目的探讨广州地区血透护士情绪智力在社会支持与主观幸福感间的中介效应,为血液透析中心科学管理护理人才提供实践指导。方法采用横断面研究方法,通过按比例分层抽样法,于2022年10月至2023年1月抽取在广州地区的800名血透护士为调查对象,采用一般资料调查表、总体幸福感量表(general well-being schedule,GWB)、社会支持量表(social support rating scale,SSRS)和情绪智力量表(wong law emotional intelligence scale,WLEIS-C)进行调查。采用Pearson相关分析广州地区血透护士情绪智力、社会支持与主观幸福感之间相关性;采用Process宏程序探究广州地区血透护士情绪智力在社会支持与主观幸福感间的中介效应。结果回收有效问卷707份,有效回收率88.38%。广州地区血透护士主观幸福感总分为(75.67±8.17)分,情绪智力总分为(82.29±16.20)分,社会支持总分为(38.76±8.40)分。社会支持总分与主观幸福感总分(r=0.517,P<0.01)、情绪智力总分(r=0.633,P<0.01)均呈正相关,情绪智力总分与主观幸福感总分呈正相关(r=0.634,P<0.01)。社会支持对主观幸福感存在直接效应(β=0.165,95%CI:0.103~0.261),并通过情绪智力的部分中介效应间接影响主观幸福感(β=0.095,95%CI:0.069~0.142),中介效应占总效应的36.54%。结论广州地区血透护士主观幸福感现状处于高水平,情绪智力在血透护士社会支持与主观幸福感中起部分中介效应,管理者应关注血透护士情绪智力,采取多种措施提高其情绪智力水平,增强社会支持,从而提升血透护士主观幸福感。展开更多
AlN ceramics were prepared by plasma activation sintering(PAS)with compound additives yttrium acetylacetonate(Y(acac)_(3))and melamine(C_(3)H_(6)N_(6)).The effects of compound additives on the microstructure,density,a...AlN ceramics were prepared by plasma activation sintering(PAS)with compound additives yttrium acetylacetonate(Y(acac)_(3))and melamine(C_(3)H_(6)N_(6)).The effects of compound additives on the microstructure,density,and thermal properties of Al N ceramic were studied.Y(acac)3and C_(3)H_(6)N_(6)can form Y_(2)O_(3),residual organic carbon and reducing gas during the heating process,which improves the Al N sintering performance at a temperature of 1700℃and the bulk thermal conductivity.When the content of Y(acac)_(3)is 10 wt%and C_(3)H_(6)N_(6)is 3 wt%,the thermal conductivity of Al N ceramics is 105.6 W/(m·K),which is much higher than that of Al N ceramics with Y_(2)O_(3)under the same sintering conditions.This work provides theoretical reference for the preparation of high-performance Al N ceramic.展开更多
基金Funded by National Key Research and Development Program of China(No.2017YFB0310400)the National Natural Science Foundation of China(Nos.51872217,51932006,51972246 and 51521001)+3 种基金Fundamental Research Funds for the Central Universities in ChinaState Key Laboratory of Advanced Electromagnetic Engineering and Technology(Huazhong University of Science and Technology),the Joint Fund(No.6141A02022255)the Major Program of the Specialized Technological Innovation of HuBei Province,China(No.2019AFA176)the“111”Project(No.B13035)。
文摘We used density functional theory(DFT)calculations to study the influence of alkali earth metal element(AE)doping on the crystal structure and electronic band structure ofα-Si3N4.The diversity of atomic radii of alkaline earth metal elements results in structural expansion when they were doped into theα-Si3N4 lattice.Formation energies of the doped structures indicate that dopants prefer to occupy the interstitial site under the nitrogen-deficient environment,while substitute Si under the nitrogen-rich environment,which provides a guide to synthesizingα-Si3N4 with different doping types by controlling nitrogen conditions.For electronic structures,energy levels of the dopants appear in the bottom of the conduction band or the top of the valence band or the forbidden band,which reduces the bandgap ofα-Si3N4.
基金Funded by the National Natural Science Foundation of China(Nos.51521001 and 51572208)the 111 Project(B13035)+1 种基金the National Natural Science Foundation of Hubei Province(Nos.2014CFB257 and 2014CFB258)the Fundamental Research Funds for the Central Universities(WUT:2015Ш059)
文摘A novel poly(methyl-methacrylate)/silica aerogel(PMMA/SA) dual-scale cellular foam was synthesized with internal mixing followed by the supercritical carbon dioxide foaming process.The effects of silica aerogel content on the microstructural and mechanical performance of the foams were investigated by SEM,TEM analysis,and mechanical tests.The experimental results suggest that the employment of silica aerogel granule as addictive can distinctly improve the morphological feature as well as the mechanical performance in comparison to neat PMMA foam by uniformizing cell size distribution,decreasing cell size and increasing cell density.And dual-scale cells including micrometric cells of 3-10 μm and nanometric cells of about 50 nm existed in the structure of foams resulting from the retained original framework structure of silica aerogel,which has not been described in other studies with the addition of various fillers.Furthermore,the mechanical strength was significantly elevated even with a small amount of silica aerogel resulting from the unique microstructure,decreased cell size and enhanced cell walls.The compressive strength was 18.12 MPa and the flexural strength was 18.90 MPa by adding 5wt% and 2wt% silica aerogel,respectively.These results demonstrate the potential to synthesize PMMA/SA dual-scale cellular foams to be used as structural materials with the advantages of low density and high strength.
文摘目的探讨广州地区血透护士情绪智力在社会支持与主观幸福感间的中介效应,为血液透析中心科学管理护理人才提供实践指导。方法采用横断面研究方法,通过按比例分层抽样法,于2022年10月至2023年1月抽取在广州地区的800名血透护士为调查对象,采用一般资料调查表、总体幸福感量表(general well-being schedule,GWB)、社会支持量表(social support rating scale,SSRS)和情绪智力量表(wong law emotional intelligence scale,WLEIS-C)进行调查。采用Pearson相关分析广州地区血透护士情绪智力、社会支持与主观幸福感之间相关性;采用Process宏程序探究广州地区血透护士情绪智力在社会支持与主观幸福感间的中介效应。结果回收有效问卷707份,有效回收率88.38%。广州地区血透护士主观幸福感总分为(75.67±8.17)分,情绪智力总分为(82.29±16.20)分,社会支持总分为(38.76±8.40)分。社会支持总分与主观幸福感总分(r=0.517,P<0.01)、情绪智力总分(r=0.633,P<0.01)均呈正相关,情绪智力总分与主观幸福感总分呈正相关(r=0.634,P<0.01)。社会支持对主观幸福感存在直接效应(β=0.165,95%CI:0.103~0.261),并通过情绪智力的部分中介效应间接影响主观幸福感(β=0.095,95%CI:0.069~0.142),中介效应占总效应的36.54%。结论广州地区血透护士主观幸福感现状处于高水平,情绪智力在血透护士社会支持与主观幸福感中起部分中介效应,管理者应关注血透护士情绪智力,采取多种措施提高其情绪智力水平,增强社会支持,从而提升血透护士主观幸福感。
基金National Natural Science Foundation of China(Nos.51872217,51972246)the Guangdong Major Project of Basic and Applied Basic Research(Nos.2021B0301030001)。
文摘AlN ceramics were prepared by plasma activation sintering(PAS)with compound additives yttrium acetylacetonate(Y(acac)_(3))and melamine(C_(3)H_(6)N_(6)).The effects of compound additives on the microstructure,density,and thermal properties of Al N ceramic were studied.Y(acac)3and C_(3)H_(6)N_(6)can form Y_(2)O_(3),residual organic carbon and reducing gas during the heating process,which improves the Al N sintering performance at a temperature of 1700℃and the bulk thermal conductivity.When the content of Y(acac)_(3)is 10 wt%and C_(3)H_(6)N_(6)is 3 wt%,the thermal conductivity of Al N ceramics is 105.6 W/(m·K),which is much higher than that of Al N ceramics with Y_(2)O_(3)under the same sintering conditions.This work provides theoretical reference for the preparation of high-performance Al N ceramic.
