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Preparation of spherical cobalt carbonate powder with high tap density 被引量:1
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作者 肖劲 王剑锋 +2 位作者 刘永东 李劼 刘业翔 《Journal of Central South University of Technology》 EI 2006年第6期642-646,共5页
Spherical cobalt carbonate with high tap density, good crystallization and uniform particle size was prepared by controlled chemical crystal method using cobalt chloride and ammonium bicarbonate as cobalt source and p... Spherical cobalt carbonate with high tap density, good crystallization and uniform particle size was prepared by controlled chemical crystal method using cobalt chloride and ammonium bicarbonate as cobalt source and precipitator. The effects of pH value and reaction time on crystallization and physical properties of cobalt carbonate were studied. The results show that the key factors influencing the preparation process of spherical cobalt carbonate with high tap density and good crystallization are how to control pH value (7.25±0.05) and keep some reaction time (about 10 h). Co4O3 was prepared by sintering spherical morphology CoCO3 samples at varied temperatures. The results show that as the decomposition temperature increases, the as-obtained Co4O3 products with porous structure transform into polyhedral structure with glazed surface, and simultaneously the cobalt content and tap density increase. However, the specific surface area shows a trend of decrease. 展开更多
关键词 controlled chemical crystal method spherical cobalt carbonate tap density crystal structure
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Impact of Mechanical Aeration on the Soil Resistance to Penetration and Density of Grassy Sward
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作者 Khaoula Abrougui Sayed Chehaibi Mohamed Khelifi 《Journal of Environmental Science and Engineering(A)》 2012年第5期683-687,共5页
The aim of this study was to analyze the effects of mechanical perforation of a golf course grassy sward, subject to maintenance machinery traffic and golf players trampling on its compaction and density. The evolutio... The aim of this study was to analyze the effects of mechanical perforation of a golf course grassy sward, subject to maintenance machinery traffic and golf players trampling on its compaction and density. The evolution of soil compaction state after aeration was also conducted in four stages of measurement. This operation aims to improve the structure and soil texture, which is also called "perforation" or "coring". The taken cores leaving on the soil holes of adjustable depth and density (350 holes/mE) are made with an aerator machine called Vertidrain. Soil resistance to penetration and density were determined at the initial state before aeration as well as 10, 20, and 30 days after aeration. Compared to the initial state, the results show that mechanical aeration greatly affects the grassy sward ground by reducing its resistance to penetration as 35% and 43% decrease in penetration resistance were noticed at 5 cm depth l0 and 20 days after aeration, respectively. Also, resistance to penetration decreased by 41% and 48% at 15 cm depth during the same two periods of time with a relatively constant moisture content. However, soil resistance to penetration at 5 and 15 cm depths only decreased by 21% and 26%, respectively. Regarding the soil density measured after aeration, a significant improvement at the 1% level with the method of variance analysis was observed compared to that at the initial state (e.g. 1.33 g·cm^-3) Indeed, the density was 1.29, 1.26 and 1.30 gcm^-3 10, 20 and 30 days after aeration, respectively. 展开更多
关键词 Grassy sward soil compaction mechanical aeration soil resistance soil density.
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Influence of A Hyperons ^1S0 Superfluidity on the Direct Urca Processes with Hyperons 被引量:1
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作者 许妍 刘广洲 +2 位作者 吴姚睿 王红岩 张峰 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第9期521-524,共4页
In the framework of the relativistic mean field theory (RMFT), the relativistic energy losses of the direct Urea processes with hyperons (Y-DURCA ) for reactions A → p + e + υe and ≡^-→ A+e+υe are studied... In the framework of the relativistic mean field theory (RMFT), the relativistic energy losses of the direct Urea processes with hyperons (Y-DURCA ) for reactions A → p + e + υe and ≡^-→ A+e+υe are studied in neutron stars. We calculate the energy gap of A hyperons and investigate the effects of the ^1S0 superfluidity (SF) of A hyperons on the Y-DURCA processes. The calculated results are in line with the recent experimental data △ BAA ~ 1.01 ±0.20-0.11^+0.18 MeV. The results indicate that the ^1S0 SF of A hyperons exists in most density ranges of happening the two reactions. The theoretical cooling curves are in agreement with observation data. 展开更多
关键词 hyperons superfluidity direct Urca processes with hyperons neutron star
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灵山湾国家森林公园刺槐林下垂序商陆种子雨时空动态 被引量:10
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作者 翟树强 李传荣 +3 位作者 许景伟 刘立川 张丹 周振 《植物生态学报》 CAS CSCD 北大核心 2010年第10期1236-1242,共7页
垂序商陆(Phytolacca americana)的入侵给山东省沿海防护林的生物多样性及乔木更新造成了严重的危害,为揭示其繁殖特性和扩散机制,在灵山湾国家森林公园刺槐(Robinia pseudoacacia)林下由林缘至林内60m设置5个梯度,采用机械布点法对垂... 垂序商陆(Phytolacca americana)的入侵给山东省沿海防护林的生物多样性及乔木更新造成了严重的危害,为揭示其繁殖特性和扩散机制,在灵山湾国家森林公园刺槐(Robinia pseudoacacia)林下由林缘至林内60m设置5个梯度,采用机械布点法对垂序商陆的结实量、种子雨分布和扩散格局进行了调查。结果表明:1)垂序商陆的结实量与种子雨量由林缘至林内逐渐减小,分别为2273-1846和1382-621粒·m-2,不同空间种子雨密度占结实密度的60.80%-33.64%,平均为49.52%,人为搂割及动物取食是种子雨量损失的主要原因;2)种子雨始于9月中旬,林缘种子雨的发生早于林内,种子雨的平均强度由林缘至林内逐渐减小,在10月下旬和12月中旬各有一次种子雨高峰,最大强度分别为32-4和59-5粒·m-2·d-1;3)种子雨由林缘至林内散布范围逐渐减小,同时随距母株距离的增加而减小,其中最大散布距离与加权平均距离分别为210-180cm和94.32-63.03cm,整体加权平均距离为81.00cm。表明垂序商陆种子雨具有明显的时空异质性,对预测其扩散潜力及群落结构组成趋势有重要的意义。 展开更多
关键词 入侵种 垂序商陆 结实密度 种子雨 空间异质性 时间动态
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Total energy equation leading to exchange-correlation functional
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作者 LIU Feng WANG TzuChiang 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2015年第5期93-98,共6页
By solving the total energy equation, we obtain the formula of exchange-correlation functional for the first time. This functional is usually determined by fitting experimental data or the numerical results of models.... By solving the total energy equation, we obtain the formula of exchange-correlation functional for the first time. This functional is usually determined by fitting experimental data or the numerical results of models. In the uniform electron gas limit, our exchangecorrelation functional can exactly reproduce the results of Perdew-Zunger parameterization from the jellium model. By making use of a particular solution, our exchange-correlation functional could take into accotmt the case of non-uniform electron density, and its validity can be confirmed through comparisons of the band structure, equilibrium lattice constant, and bulk modulus of aluminum and silicon. The absence of mechanical prescriptions for the systematic improvement of exchange-correlation functional hinders further development of density-functional theory (DFT), and the formula of exchange-correlation functional given in this study might provide a new perspective to help DFT out of this awkward situation. 展开更多
关键词 Density-functional theory exchange-correlation functional bulk modulus band structure ALUMINUM silicon
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