Although the preparation of ZSM-5@silicalite-1(ZS) core–shell catalysts has been reported in the literature,their selectivity to para-xylene(PX)in the toluene alkylation with methanol is difficult to control.Here we ...Although the preparation of ZSM-5@silicalite-1(ZS) core–shell catalysts has been reported in the literature,their selectivity to para-xylene(PX)in the toluene alkylation with methanol is difficult to control.Here we present the effects of water and ZSM-5 adding amounts in the synthesis solution,the hydrothermal synthesis time,and the Si/Al ratio of core ZSM-5 on the catalytic performance of ZS core–shell catalysts.The ZS core–shell catalysts were characterized by X-ray diffraction (XRD),N_2 adsorption,and NH_3 temperature-programmed desorption (NH_3-TPD) techniques.The highest PX selectivity of 95.5%was obtained for the ZS(Si/Al=140) catalyst prepared in the synthesis solution with a molar ratio of 0.2 TPAOH:1TEOS:250H_2O at 175°C and 10 r·min^(-1) for only 2 h and the corresponding toluene conversion is as high as 22.8% for the alkylation of toluene with methanol.展开更多
In this study, we designed and synthesized a novel battery-type electrode featuring three-dimensional(3D) hierarchical ZnO@Ni_xCo_(1-x)(OH)_y core/shell nanowire/nanosheet arrays arranged on Nifoam substrate via a two...In this study, we designed and synthesized a novel battery-type electrode featuring three-dimensional(3D) hierarchical ZnO@Ni_xCo_(1-x)(OH)_y core/shell nanowire/nanosheet arrays arranged on Nifoam substrate via a two-step protocol including a wet chemical process followed by electro-deposition. We then characterized its composition, structure and surface morphology by X-ray diff raction, energy-dispersive X-ray spectrometry(EDS), X-ray photoelectron spectroscopy, scanning electron microscopy(SEM), transmission electron microscopy, EDS elemental mapping. Our electrochemical measurements show that the ZnO@Ni_(0.67)Co_(0.33)(OH)_y electrode material exhibited a noticeably high specific capacity of as much as 255(mA ·h)/g at 1 A/g. Additionally, it demonstrated a superior rate capability, as well as an excellent cycling stability with 81.6% capacity retention over 2000 cycles at 5 A/g. This sample delivered a high energy density of 64 W·h/kg and a power density of 250 W/kg at a current density of 1 A/g. With such remarkable electrochemical properties, we expect the 3D hierarchical hybrid electrode material presented in this work to have promising applications for the next generation of energy storage systems.展开更多
Prior to the installation of the Cd-liner in one of the large outer irradiation channels of NIRR-1, a Monte Carlo simulation was performed using MCNP5 version 1.4 code. This was done to investigate the effect of insta...Prior to the installation of the Cd-liner in one of the large outer irradiation channels of NIRR-1, a Monte Carlo simulation was performed using MCNP5 version 1.4 code. This was done to investigate the effect of installation of Cd-liner in either an inner or outer irradiation channel on reactor physics parameters. Data obtained indicate that the core excess reactivity in both inner and outer irradiations channels is reduced by 3.60 ± 0.07 mk and 0.64 ± 0.06 mk, respectively. Considering the fact that NIRR-1 has a cold core excess reactivity of 3.77 mk, results obtained show that installation of the 1 mm thick Cd-sheet in one of the large outer irradiation channels would have no significant impact on the core physics data. After installation of a 1 mm Cd sheath in a large outer irradiation channel, the neutron flux distribution and the stability in the irradiation channels were monitored by foil activation method. Results indicate that the uniformity of neutron flux distribution in the irradiation channel is preserved and the neutron flux data were found to be comparable with the data obtained before the installation.展开更多
This study aims to thoroughly investigate the axial power peaking factors (PPF) within the low-enriched uranium (LEU) core of the Ghana Research Reactor-1 (GHARR-1). This study uses advanced simulation tools, like the...This study aims to thoroughly investigate the axial power peaking factors (PPF) within the low-enriched uranium (LEU) core of the Ghana Research Reactor-1 (GHARR-1). This study uses advanced simulation tools, like the MCNPX code for analysing neutron behavior and the PARET/ANL code for understanding power variations, to get a clearer picture of the reactor’s performance. The analysis covers the initial six years of GHARR-1’s operation and includes projections for its whole 60-year lifespan. We closely observed the patterns of both the highest and average PPFs at 21 axial nodes, with measurements taken every ten years. The findings of this study reveal important patterns in power distribution within the core, which are essential for improving the safety regulations and fuel management techniques of the reactor. We provide a meticulous approach, extensive data, and an analysis of the findings, highlighting the significance of continuous monitoring and analysis for proactive management of nuclear reactors. The findings of this study not only enhance our comprehension of nuclear reactor safety but also carry significant ramifications for sustainable energy progress in Ghana and the wider global context. Nuclear engineering is essential in tackling global concerns, such as the demand for clean and dependable energy sources. Research on optimising nuclear reactors, particularly in terms of safety and efficiency, is crucial for the ongoing advancement and acceptance of nuclear energy.展开更多
Lateral deflection formulas are presented for analysis of the strengthened story applied to flame-core structures. For the framecore structures with top outriggers and with middle outriggers, the relationship between ...Lateral deflection formulas are presented for analysis of the strengthened story applied to flame-core structures. For the framecore structures with top outriggers and with middle outriggers, the relationship between stiffness characteristic parameters of frame and outriggers and the top drift of structures under different loads is analyzed. It is indicated that when stiffness characteristic parameter of frame is large, outrigger efficiency for top drift reduction is low, and the mutation of internal forces occurs; when the stiffness characteristic parameter of frame is less than 3, installing the strengthened story is advantageous to frame-core structures.展开更多
目的了解汕头市水产品非O1/O139群霍乱弧菌的耐药基因、毒力基因、序列位点信息,分析不同菌株间遗传关系。方法收集分离自水产品的霍乱弧菌41株,对菌株进行全基因组序列测定,利用生物信息学工具预测菌株的耐药基因和毒力基因情况,结合...目的了解汕头市水产品非O1/O139群霍乱弧菌的耐药基因、毒力基因、序列位点信息,分析不同菌株间遗传关系。方法收集分离自水产品的霍乱弧菌41株,对菌株进行全基因组序列测定,利用生物信息学工具预测菌株的耐药基因和毒力基因情况,结合美国国家生物技术信息中心(National Center for Biotechnology Information,NCBI)数据库,进行多位点序列分型分析(multilocus sequence typing,MLST)和核心基因组单核苷酸多态性分析(core gene single nucleotide polymorphism,cgSNP)。结果41株霍乱弧菌共检测到34个抗生素耐药基因,携带率最高的是dfrA31(46.3%),部分菌株携带能水解所有β-内酰胺酶的blaNDM-1基因。毒力基因携带率最高的是rtxA(100.0%)和hlyA(97.6%),所有病原菌株均不携带ctxA和ctxB,致病岛VPI-1/VPI-2携带率分别为31.7%/70.7%,T6SS和第7次大流行特征基因岛VSP-1/VSP-2的检出率都是4.9%。MLST和cgSNP分析显示,共有30种不同的序列型(sequencetypes,STs),其中20种为新分配的STs。结论汕头市水产品中非O1/O139群霍乱弧菌携带多种毒力基因和耐药基因,其中霍乱弧菌携带blaNDM-1基因为国内首次报道。不同物种来源的菌株遗传多样性高,发现大量新STs型。展开更多
基金Supported by the National Natural Science Foundation of China(21676238)
文摘Although the preparation of ZSM-5@silicalite-1(ZS) core–shell catalysts has been reported in the literature,their selectivity to para-xylene(PX)in the toluene alkylation with methanol is difficult to control.Here we present the effects of water and ZSM-5 adding amounts in the synthesis solution,the hydrothermal synthesis time,and the Si/Al ratio of core ZSM-5 on the catalytic performance of ZS core–shell catalysts.The ZS core–shell catalysts were characterized by X-ray diffraction (XRD),N_2 adsorption,and NH_3 temperature-programmed desorption (NH_3-TPD) techniques.The highest PX selectivity of 95.5%was obtained for the ZS(Si/Al=140) catalyst prepared in the synthesis solution with a molar ratio of 0.2 TPAOH:1TEOS:250H_2O at 175°C and 10 r·min^(-1) for only 2 h and the corresponding toluene conversion is as high as 22.8% for the alkylation of toluene with methanol.
基金supported by the National Basic Research Program of China ("973" Program, No. 2012CB720302)the National Key Research and Development Program of China (No 2016YFF0102503)
文摘In this study, we designed and synthesized a novel battery-type electrode featuring three-dimensional(3D) hierarchical ZnO@Ni_xCo_(1-x)(OH)_y core/shell nanowire/nanosheet arrays arranged on Nifoam substrate via a two-step protocol including a wet chemical process followed by electro-deposition. We then characterized its composition, structure and surface morphology by X-ray diff raction, energy-dispersive X-ray spectrometry(EDS), X-ray photoelectron spectroscopy, scanning electron microscopy(SEM), transmission electron microscopy, EDS elemental mapping. Our electrochemical measurements show that the ZnO@Ni_(0.67)Co_(0.33)(OH)_y electrode material exhibited a noticeably high specific capacity of as much as 255(mA ·h)/g at 1 A/g. Additionally, it demonstrated a superior rate capability, as well as an excellent cycling stability with 81.6% capacity retention over 2000 cycles at 5 A/g. This sample delivered a high energy density of 64 W·h/kg and a power density of 250 W/kg at a current density of 1 A/g. With such remarkable electrochemical properties, we expect the 3D hierarchical hybrid electrode material presented in this work to have promising applications for the next generation of energy storage systems.
文摘Prior to the installation of the Cd-liner in one of the large outer irradiation channels of NIRR-1, a Monte Carlo simulation was performed using MCNP5 version 1.4 code. This was done to investigate the effect of installation of Cd-liner in either an inner or outer irradiation channel on reactor physics parameters. Data obtained indicate that the core excess reactivity in both inner and outer irradiations channels is reduced by 3.60 ± 0.07 mk and 0.64 ± 0.06 mk, respectively. Considering the fact that NIRR-1 has a cold core excess reactivity of 3.77 mk, results obtained show that installation of the 1 mm thick Cd-sheet in one of the large outer irradiation channels would have no significant impact on the core physics data. After installation of a 1 mm Cd sheath in a large outer irradiation channel, the neutron flux distribution and the stability in the irradiation channels were monitored by foil activation method. Results indicate that the uniformity of neutron flux distribution in the irradiation channel is preserved and the neutron flux data were found to be comparable with the data obtained before the installation.
文摘This study aims to thoroughly investigate the axial power peaking factors (PPF) within the low-enriched uranium (LEU) core of the Ghana Research Reactor-1 (GHARR-1). This study uses advanced simulation tools, like the MCNPX code for analysing neutron behavior and the PARET/ANL code for understanding power variations, to get a clearer picture of the reactor’s performance. The analysis covers the initial six years of GHARR-1’s operation and includes projections for its whole 60-year lifespan. We closely observed the patterns of both the highest and average PPFs at 21 axial nodes, with measurements taken every ten years. The findings of this study reveal important patterns in power distribution within the core, which are essential for improving the safety regulations and fuel management techniques of the reactor. We provide a meticulous approach, extensive data, and an analysis of the findings, highlighting the significance of continuous monitoring and analysis for proactive management of nuclear reactors. The findings of this study not only enhance our comprehension of nuclear reactor safety but also carry significant ramifications for sustainable energy progress in Ghana and the wider global context. Nuclear engineering is essential in tackling global concerns, such as the demand for clean and dependable energy sources. Research on optimising nuclear reactors, particularly in terms of safety and efficiency, is crucial for the ongoing advancement and acceptance of nuclear energy.
基金The Natural Science Foundation of China(No.50708041)
文摘Lateral deflection formulas are presented for analysis of the strengthened story applied to flame-core structures. For the framecore structures with top outriggers and with middle outriggers, the relationship between stiffness characteristic parameters of frame and outriggers and the top drift of structures under different loads is analyzed. It is indicated that when stiffness characteristic parameter of frame is large, outrigger efficiency for top drift reduction is low, and the mutation of internal forces occurs; when the stiffness characteristic parameter of frame is less than 3, installing the strengthened story is advantageous to frame-core structures.
文摘目的了解汕头市水产品非O1/O139群霍乱弧菌的耐药基因、毒力基因、序列位点信息,分析不同菌株间遗传关系。方法收集分离自水产品的霍乱弧菌41株,对菌株进行全基因组序列测定,利用生物信息学工具预测菌株的耐药基因和毒力基因情况,结合美国国家生物技术信息中心(National Center for Biotechnology Information,NCBI)数据库,进行多位点序列分型分析(multilocus sequence typing,MLST)和核心基因组单核苷酸多态性分析(core gene single nucleotide polymorphism,cgSNP)。结果41株霍乱弧菌共检测到34个抗生素耐药基因,携带率最高的是dfrA31(46.3%),部分菌株携带能水解所有β-内酰胺酶的blaNDM-1基因。毒力基因携带率最高的是rtxA(100.0%)和hlyA(97.6%),所有病原菌株均不携带ctxA和ctxB,致病岛VPI-1/VPI-2携带率分别为31.7%/70.7%,T6SS和第7次大流行特征基因岛VSP-1/VSP-2的检出率都是4.9%。MLST和cgSNP分析显示,共有30种不同的序列型(sequencetypes,STs),其中20种为新分配的STs。结论汕头市水产品中非O1/O139群霍乱弧菌携带多种毒力基因和耐药基因,其中霍乱弧菌携带blaNDM-1基因为国内首次报道。不同物种来源的菌株遗传多样性高,发现大量新STs型。
