Nd : YAG ceramic laser obtained high slope-efficiency of 62% in high power applications

By using quite uniformly nine-stacks side-around arranged compact pumping system, a high power Nd:YAG ceramic quasi-CW laser with high slope efficiency of 62% has been demonstrated. With 450 W quasi-CW stacked laser diode bars pumping at 808 nm, performance of the Nd: YAG ceramic laser with different output coupling mirrors has been investigated. Optimum output power of 236 W at 1064 nm was obtained and corresponding optical-to-optical conversion efficiency was as high as 52.5%. The laser system operated quite stably and no saturation phenomena have been observed, which means higher output laser power could be obtained if injecting higher pumping power. The still-evolving Nd: YAG ceramics are potential super excellent media for high power practical laser applications. (c) 2005 Optical Society of America.

Spectral hole-burning of Eu3+: Y2SiO5 crystal at 579.62 mm

By using an Ar+ ion laser, a tunable Rh 6G dye laser(Linewidth : 0.5 cm(-1)) and a Coherent 899-21 dye laser as light sources and using a monochromator and a phase-locking amplifier, the optical properties of Eu3+ : Y2SiO5 crystal were detected. Persistent spectral hole burning (PSHB) were also observed in (5)Do-(7)Fo transition in the crystal at the temperature of 16 K. For 15 mW dye laser (Wavelength : 579.62 nm) burning the crystal for 0.1 s a spectral hole with about 80 MHz hole width were detected and the hole can been keep for longer than 10 h.

Si_(0.75)Ge_(0.25)虚衬底上应变补偿Si/Si_(0.62)Ge_(0.38)量子阱发光

由于Si/SiGe异质结构的带阶差主要发生在价带,为实现高效率的发光,本文从理论上设计了在硅基Si_(1-x) Ge_x虚衬底上外延应变补偿的Si/S_(1-y) Ge_y(y>x)量子阱的能带结构,将量子阱对电子的限制势垒提高到100meV以上.在实验上,采用300℃生长的Ge量子点插入层,制备出薄的SiGe驰豫缓冲层(虚衬底),表面Ge组份达到0.25,表面粗糙度小于2nm,驰豫度接近100%.在我们制备的SiGe缓冲层上外延了应变补偿SiGe/Si多量子阱结构,并初步研究了其发光特性.

长白山阔叶红松林生态系统碳密度对采伐干扰的响应研究

本研究以长白山地区原始和次生的阔叶红松林为对象，在2007和2008年共建立了8种类型10块1 ha样地。通过野外调查和取样分析，得到各样地森林生态系统的植物、枯死物和土壤碳密度值，并结合采伐样地经营历史情况（采伐时间和强度），得到长白山地区原始阔叶红松林生态系统碳密度参考值和次生阔叶红松林生态系统碳密度对采伐强度和植被恢复时间的响应特征。在此基础上，通过建立阔叶红松林乔木碳密度与生态系统碳密度的回归关系，并结合露水河林业局3个时期（1987、1995和2003年）的小班数据和原始林碳密度参考值，估算露水河林业局林业用地3个时期和潜在的碳储量。主要研究结果如下： （1）原始阔叶红松林生态系统碳密度参考值：植被、枯死物、土壤和生态系统碳密度值分别为149.18±54.57、20.93±14.33、156.39±14.99、326.50±34.52 t•ha-1。其中下木层、乔木层碳密度分别是1.55±0.74，147.63±54.39 t•ha-1；粗木质残体和枯枝落叶碳密度分别是15.64±13.66、5.29±1.72 t•ha-1；0-50 cm的各层土壤碳密度分别为62.14±6.31、46.17±10.25、27.82±6.20、12.57±4.67、7.69±2.20 t•ha-1。 （2）原始阔叶红松林生态系统碳密度对采伐干扰的响应特征为：采伐干扰均会减少生态系统碳密度；其中植被碳库对采伐干扰最为敏感且碳密度值均减少，采伐强度直接决定植被碳密度的减少程度和恢复时间；枯死物碳库对采伐干扰最不敏感且碳密度值是先增加后减少，采伐强度和植被恢复时建群树种决定枯死物碳密度的变化程度；土壤碳库对高强度采伐干扰敏感，采伐强度决定土壤碳密度是否发生变化。 （3）估算露水河林业局林业用地在1987、1995、2003年和潜在的森林生态系统碳储量分别为29.58×106 t、27.55×106 t、30.46×106 t和38.75×106 t。

超重核~(294)118和~(291)116及其α衰变链上各核素半衰期的研究

运用推广的液滴模型(GLDM)确定了超重核294118和291116及其α衰变链上各核素的衰变势垒,采用量子力学中的WKB方法计算α衰变中的势垒穿透几率,对该链上各原子核的α衰变半衰期进行了研究。此外,还利用Royer公式对该链上各原子核的α衰变半衰期进行了计算。结果表明,GLDM考虑亲和能与Royer公式给出的α衰变半衰期与超重核区的实验值符合很好,验证了GLDM和Royer公式在超重核区的适用性,可以用来预测超重核的半衰期。最后,预言了Z=118和116同位素链上各核素的半衰期,结果表明,在Z=118和116中存在α衰变长寿命同位素,这需要实验上的检验。

Charged and strange hadron elliptic flow in Cu plus Cu collisions at root s(NN)=62.4 and 200 GeV

We present the results of an elliptic flow, v(2), analysis of Cu + Cu collisions recorded with the solenoidal tracker detector (STAR) at the BNL Relativistic Heavy Ion Collider at root s(NN) = 62.4 and 200 GeV. Elliptic flow as a function of transverse momentum, v(2)(p(T)), is reported for different collision centralities for charged hadrons h(+/-) and strangeness-ontaining hadrons K-S(0), Lambda, Xi, and phi in the midrapidity region vertical bar eta vertical bar < 1.0. Significant reduction in systematic uncertainty of the measurement due to nonflow effects has been achieved by correlating particles at midrapidity, vertical bar eta vertical bar < 1.0, with those at forward rapidity, 2.5 < vertical bar eta vertical bar < 4.0. We also present azimuthal correlations in p + p collisions at root s = 200 GeV to help in estimating nonflow effects. To study the system-size dependence of elliptic flow, we present a detailed comparison with previously published results from Au + Au collisions at root s(NN) = 200 GeV. We observe that v(2)(p(T)) of strange hadrons has similar scaling properties as were first observed in Au + Au collisions, that is, (i) at low transverse momenta, p(T) < 2 GeV/c, v(2) scales with transverse kinetic energy, m(T) - m, and (ii) at intermediate p(T), 2 < p(T) < 4 GeV/c, it scales with the number of constituent quarks, n(q.) We have found that ideal hydrodynamic calculations fail to reproduce the centrality dependence of v(2)(p(T)) for K-S(0) and Lambda. Eccentricity scaled v(2) values, v(2)/epsilon, are larger in more central collisions, suggesting stronger collective flow develops in more central collisions. The comparison with Au + Au collisions, which go further in density, shows that v(2)/epsilon depends on the system size, that is, the number of participants N-part. This indicates that the ideal hydrodynamic limit is not reached in Cu + Cu collisions, presumably because the assumption of thermalization is not attained.

一个新的超分子化合物(C_(10)H_(18)N)_6As_2Mo_(18)O_(62)·6CH_3CN·8H_2O的合成、结构及性质

以Dawson型砷钼酸、金刚烷胺为原料 ,合成了一个新的超分子化合物 :(C10 H18N) 6As2 Mo18O62 ·6CH3 CN·8H2 O .通过元素分析 ,IR ,1HNMR等方法对合成的化合物进行了表征 .X射线衍射晶体解析表明 ,金刚烷胺与Dawson型多阴离子以静电力和分子间力 (氢键 )结合 ,并且在新化合物中 ,金刚烷胺及多阴离子结构基本保持不变 .该化合物均具有可逆的光致变色特性 ,基于变色后样品的电子自旋共振 (ESR)谱提出一个可能变色机理 .以该类化合物为修饰剂的本体修饰碳糊电极(APM CPE)对过氧化氢还原有很好的电催化活性.

投喂策略对工厂化养殖半滑舌鳎的效应特征与投喂模型构建

1、在封闭循环水工厂化养殖条件下，进行为期44天的6×2双因素随机设计动物试验，即6个体重阶段（45-550g）和2种养殖密度水平（高密度比正常密度提高20-30%），探寻我国北方工厂化养殖半滑舌鳎生长、摄食和水质的变化特征及规律。结果如下： （1）日增重、日均摄食量、饲料系数等绝对指标与体重阶段呈正相关，对应的增重率、特定生长率和摄食率等相对指标与其呈负相关；氨氮、COD等水生态指标相对浓度与体重阶段呈负相关。（2）新发现半滑舌鳎的日摄食率为0.43-0.92%，对常规鱼类投饲率推荐范围（2-5%）提出了质疑，为现代海水养殖精准饲喂和清洁生产提供了科学依据。 2、在封闭循环水养殖条件下，通过56天的4×2双因素随机设计动物试验，探寻月饱食度和和日粮次喂比例对工厂化养殖半滑舌鳎幼鱼（291.47±4.23g）生长与免疫的影响。结果如下： （1）月饱食度显著影响鱼的生长、摄食和水氨氮相对浓度，对饲料系数、水质其它指标和血液免疫无显著影响。 （2）日次喂比例显著影响鱼生长、饲料系数和水氨氮指标等，对水质其它指标、摄食量及免疫指标无显著影响。等量投喂组的生长和水氨氮指标显著高于差量投喂，饲料系数低于差量投喂。 （3）确定90%月饱食度与差量投喂为兼顾生长和水环境的生态适宜投喂组合模式，100%月饱食度与等量投喂为获得最快生长的投喂组合模式。 3、通过对实验数据进行对数化处理、多 元线性拟合、变量替代等方法，初步建立了封闭循环水养殖半滑舌鳎的投喂模型、总有害氮排泄和日增重预测模型。本模型的建立和完善，可初步实现最佳生长、最 少饲料浪费、并向生物滤器提供稳定代谢物的新型工厂化养殖清洁投喂目的，使封闭循环水养殖半滑舌鳎的饲料投喂和水环境调控步入数字、精准、动态的层次。

Development of a LCST membrane forming system for cellulose acetate ultrafiltration hollow fiber

A novel lower critical solution temperature (LCST) membrane forming system containing cellulose acetate (CA)/poly (vinyl pyrrolidone) (PVP 3 60K)/N-methyl-2-pyrrolidone (NMP)/1,2-propanediol with a weight ratio of 24.0:5.0:62.6:8.4 had been developed. CA hollow fiber ultrafiltration (UF) membranes were fabricated using the dry-wet spinning technique. The fibers were post-treated with a 200 mg/L hypochlorite solution over a period of 6 It at pH 7. The experimental results showed that water flux of a membrane decreased while retention increased with increasing CA concentration in a dope. It was concluded that the membrane pore size decreased with increasing CA concentration. The membrane fouling tendency for BSA was 3 times higher than that for PVP 24K. (C) 2004 Elsevier B.V. All rights reserved.