Roof disaster has always been an important factor restricting coal mine safety production.Acidic effect can reform the rock mass structure to weaken the macroscopic strength characteristics,which is an effective way t...Roof disaster has always been an important factor restricting coal mine safety production.Acidic effect can reform the rock mass structure to weaken the macroscopic strength characteristics,which is an effective way to control the hard limestone roof.In this study,the effects of various factors on the reaction characteristics and mechanical properties of limestone were analyzed.The results show that the acid with stronger hydrogen production capacity after ionization(pK_(a)<0)has more prominent damage to the mineral grains of limestone.When pKa increases from−8.00 to 15.70,uniaxial compressive strength and elastic modulus of limestone increase by 117.22%and 75.98%.The influence of acid concentration is manifested in the dissolution behavior of mineral crystals,the crystal defects caused by large-scale acid action will lead to the deterioration of limestone strength,and the strength after 15%concentration reformation can be reduced by 59.42%.The effect of acidification time on limestone has stages and is the most obvious in the initial metathesis reaction stage(within 60 min).The key to the strength damage of acidified limestone is the participation of hydrogen ions in the reaction system.Based on the analytic hierarchy process method,the influence weights of acid type,acid concentration and acidification time on strength are 24.30%,59.54% and 16.16%,respectively.The research results provide theoretical support for the acidification control of hard limestone roofs in coal mines.展开更多
The mechanical properties and texture of AM60（Mg-6.0Al-0.3Mn,mass fraction %） and ZXM200（Mg-1.6Zn-0.5Ca-0.2Mn） Mg alloys subjected to multi-pass hot rolling were investigated.The finer recrystallized grains usuall...The mechanical properties and texture of AM60（Mg-6.0Al-0.3Mn,mass fraction %） and ZXM200（Mg-1.6Zn-0.5Ca-0.2Mn） Mg alloys subjected to multi-pass hot rolling were investigated.The finer recrystallized grains usually exhibit particular preferred orientations and then alter the total texture feature of rolled sheets.Ca solid solution into Mg matrix serves to the formation of texture component with c-axis rotated away from normal direction towards transverse direction and then weakens the overall texture intensity,resulting in a similar anisotropic characteristic to RE-containing Mg alloys.展开更多
REITs包括基础设施REITs都是在经济亟需刺激政策的背景下,各国政府为了实现经济政策目标而推出的,部分市场甚至由政府直接推动首批REITs上市。从国际市场发展现状看,主要的基础设施REITs市场都实现了良性循环,资本市场为基础设施融资和...REITs包括基础设施REITs都是在经济亟需刺激政策的背景下,各国政府为了实现经济政策目标而推出的,部分市场甚至由政府直接推动首批REITs上市。从国际市场发展现状看,主要的基础设施REITs市场都实现了良性循环,资本市场为基础设施融资和发展提供了强有力支持。从国际经验看,REITs立法的逻辑起点可以分为两大类,一类是将REITs定位成传递工具,一类是将REITs定位成集合投资工具,对应的免税政策也分别有两种不同逻辑。为促进基础设施REITs有序发展,兼顾投融资双方利益,本文提出了相应的法规政策原则和具体建议,包括如何处理好R E I T s法规与其他法规的关系,金融监管部门和其他政府部门的关系,发行人和投资者的关系,如何充分利用现有的金融市场法规和金融市场结构,以及会计准则调整和投资者保护等。本文还分析了资本弱化结构,建议在公募REITs中予以细化规定。展开更多
The thermal phonon transport is a key matter for heat managing in materials science which is crucial for device miniaturization and power density increase. Herein, we report the synthesis, structure and characterizati...The thermal phonon transport is a key matter for heat managing in materials science which is crucial for device miniaturization and power density increase. Herein, we report the synthesis, structure and characterization of a new compound, Cs2Ge3Ga6Se14, with a unique anisotropic structure simultaneously containing Ge^3+ and Ge^2+ that adopt(Ge1)2^3+ Se6 dimer or(Ge2)^2+Se6 octahedron, respectively. The thermal conductivity was measured to be 0.57–0.48 W m^-1 K^-1 from 323 to 773 K, the lowest value among all the known Ge-containing compounds, approaching its glass limit according to the Cahill’s formulation. More importantly, we discover for the first time that the vibration uncoupling of Ge with different valence states hinders the effective thermal energy transport between the(Ge1)2^3+ Se6 dimer and(Ge2)^2+Se6 octahedron, and consequently lowers the thermal conductivity. In addition, we propose a structure factor f = sin(180) ×d/l(i =A, B)iGe Qi, with which a structure map of the Cs2 Ge3 M6 Q14 family is given.展开更多
基金Project(2021YFC2902102)supported by the National Key Research and Development Program of ChinaProject(52374142)supported by the National Natural Science Foundation of ChinaProject(JSTU-2022-066)supported by the Young Talent Support Project of Jiangsu Association for Science and Technology,China。
文摘Roof disaster has always been an important factor restricting coal mine safety production.Acidic effect can reform the rock mass structure to weaken the macroscopic strength characteristics,which is an effective way to control the hard limestone roof.In this study,the effects of various factors on the reaction characteristics and mechanical properties of limestone were analyzed.The results show that the acid with stronger hydrogen production capacity after ionization(pK_(a)<0)has more prominent damage to the mineral grains of limestone.When pKa increases from−8.00 to 15.70,uniaxial compressive strength and elastic modulus of limestone increase by 117.22%and 75.98%.The influence of acid concentration is manifested in the dissolution behavior of mineral crystals,the crystal defects caused by large-scale acid action will lead to the deterioration of limestone strength,and the strength after 15%concentration reformation can be reduced by 59.42%.The effect of acidification time on limestone has stages and is the most obvious in the initial metathesis reaction stage(within 60 min).The key to the strength damage of acidified limestone is the participation of hydrogen ions in the reaction system.Based on the analytic hierarchy process method,the influence weights of acid type,acid concentration and acidification time on strength are 24.30%,59.54% and 16.16%,respectively.The research results provide theoretical support for the acidification control of hard limestone roofs in coal mines.
基金Project(51204003)supported by the National Natural Science Foundation of ChinaProject(KJ2011A051)supported by the Scientific Research Foundation of Education Department of Anhui Province,China
文摘The mechanical properties and texture of AM60（Mg-6.0Al-0.3Mn,mass fraction %） and ZXM200（Mg-1.6Zn-0.5Ca-0.2Mn） Mg alloys subjected to multi-pass hot rolling were investigated.The finer recrystallized grains usually exhibit particular preferred orientations and then alter the total texture feature of rolled sheets.Ca solid solution into Mg matrix serves to the formation of texture component with c-axis rotated away from normal direction towards transverse direction and then weakens the overall texture intensity,resulting in a similar anisotropic characteristic to RE-containing Mg alloys.
文摘REITs包括基础设施REITs都是在经济亟需刺激政策的背景下,各国政府为了实现经济政策目标而推出的,部分市场甚至由政府直接推动首批REITs上市。从国际市场发展现状看,主要的基础设施REITs市场都实现了良性循环,资本市场为基础设施融资和发展提供了强有力支持。从国际经验看,REITs立法的逻辑起点可以分为两大类,一类是将REITs定位成传递工具,一类是将REITs定位成集合投资工具,对应的免税政策也分别有两种不同逻辑。为促进基础设施REITs有序发展,兼顾投融资双方利益,本文提出了相应的法规政策原则和具体建议,包括如何处理好R E I T s法规与其他法规的关系,金融监管部门和其他政府部门的关系,发行人和投资者的关系,如何充分利用现有的金融市场法规和金融市场结构,以及会计准则调整和投资者保护等。本文还分析了资本弱化结构,建议在公募REITs中予以细化规定。
基金supported by the National Natural Science Foundation of China (21975032 and 21571020)the National Key Research and Development Program of China (2018YFA0702100)
文摘The thermal phonon transport is a key matter for heat managing in materials science which is crucial for device miniaturization and power density increase. Herein, we report the synthesis, structure and characterization of a new compound, Cs2Ge3Ga6Se14, with a unique anisotropic structure simultaneously containing Ge^3+ and Ge^2+ that adopt(Ge1)2^3+ Se6 dimer or(Ge2)^2+Se6 octahedron, respectively. The thermal conductivity was measured to be 0.57–0.48 W m^-1 K^-1 from 323 to 773 K, the lowest value among all the known Ge-containing compounds, approaching its glass limit according to the Cahill’s formulation. More importantly, we discover for the first time that the vibration uncoupling of Ge with different valence states hinders the effective thermal energy transport between the(Ge1)2^3+ Se6 dimer and(Ge2)^2+Se6 octahedron, and consequently lowers the thermal conductivity. In addition, we propose a structure factor f = sin(180) ×d/l(i =A, B)iGe Qi, with which a structure map of the Cs2 Ge3 M6 Q14 family is given.
