Length-weight relationship and relative condition factor in Daysciaena albida (Cuv.) and Gerres filamentosus (Cuv.)

The length-weight relationship of Daysciaena albida and Gerres filamentosus were calculated separately for indeterminants, mature males and mature females. The logarithmic regression equation obtained for D. albida - males: log w = -1.5055 + 2.8618 log l; females: log w = -0.9260 + 2.4089 log l; indeterminants: log w = -l.7188 + 3.0616 log l. The regression co-efficients between males and females, males and in determinants and female and in determinants showed significant differences. In G. filamentosus the relationship can be expressed as males: log w = -1.3224 + 2.8740 log 1; females: log w = -1.2874 + 2.8381 log l; indeterminants: log w = -0.8167 + 2.2558 log l. The difference in regression co-efficients between male and female are insignificant at 5% level whereas significant differences were observed between males and indeterminants and females and indeterminants. The relative condition factor (Kn) was calculated for the above two species. In D. albida the reasons for the fluctuations of Kn values can be attributed to both spawning cycle as well as feeding intensity whereas in G. filamentosus it synchronies mainly with spawning cycle.

滇池太湖新银鱼的生长特性与资源量关系的研究

经31个月的连续采样调查,应用Von Bertalanffy生长方程,得到太湖新银鱼1989年和1990年生长方程。据此拟合出体重与种群密度关系W=1.047-0.671 1gC,种群密度与资源量关系F=1999.36C e~(-0.2045C),最终演译出资源量平衡点在1847t。相应体重1.0g/尾;密度指标1.175尾/m~(3);捕捞时间在8月。

Effect of surface roughness on rarefied-gas heat transfer in microbearings

In this Letter, the rarefaction and roughness effects on the heat transfer process in gas microbearings are investigated. A heat transfer model is developed by introducing two-variable Weierstrass-Mandelbrot (W-M) function with fractal geometry. The heat transfer problem in the multiscale self-affine rough microbearings at slip flow regime is analyzed and discussed. The results show that rarefaction has more significant effect on heat transfer in rough microbearings with lower fractal dimension. The negative influence of roughness on heat transfer found to be the Nusselt number reduction. The heat transfer performance can be optimized with increasing fractal dimension of the rough surface. © 2012 Elsevier B.V. All rights reserved.

Photoconductive hybrid films via directional self-assembly of C 60 on aligned carbon nanotubes

Hybrid nanostructured materials can exhibit different properties than their constituent components, and can enable decoupled engineering of energy conversion and transport functions. Novel means of building hybrid assemblies of crystalline C 60 and carbon nanotubes (CNTs) are presented, wherein aligned CNT films direct the crystallization and orientation of C 60 rods from solution. In these hybrid films, the C 60 rods are oriented parallel to the direction of the CNTs throughout the thickness of the film. High-resolution imaging shows that the crystals incorporate CNTs during growth, yet grazing-incidence X-ray diffraction (GIXD) shows that the crystal structure of the C 60 rods is not perturbed by the CNTs. Growth kinetics of the C 60 rods are enhanced 8-fold on CNTs compared to bare Si, emphasizing the importance of the aligned, porous morphology of the CNT films as well as the selective surface interactions between C 60 and CNTs. Finally, it is shown how hybrid C 60-CNT films can be integrated electrically and employed as UV detectors with a high photoconductive gain and a responsivity of 10 5 A W -1 at low biases (± 0.5 V). The finding that CNTs can induce rapid, directional crystallization of molecules from solution may have broader implications to the science and applications of crystal growth, such as for inorganic nanocrystals, proteins, and synthetic polymers. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

中华间吸鳅食性及年龄生长的初步研究

对金沙江下游中华间吸鳅的食性和年龄生长进行了初步研究。中华间吸鳅为杂食性鱼类,其食物主要包括藻类、高等植物碎片、水生昆虫、软体动物。适宜的年龄鉴定材料为鳞片和微耳石,两者年龄鉴定结果的符合率为85％,且以鳞径对生长的退算结果与实测体长相符。体长与体重的回归方程为:W=1.08×10~(-4)L~(2.5604),微耳石半径与体长、鳞径与体长的回归方程分别为:BL=59.995+130R和BL=36.704+117R。

High performance bilayer-graphene Terahertz detectors

© 2014 AIP Publishing LLC. We report bilayer-graphene field effect transistors operating as Terahertz (THz) broadband photodetectors based on plasma-waves excitation. By employing wide-gate geometries or buried gate configurations, we achieve a responsivity ∼1.2 V/W (1.3 mA/W) and a noise equivalent power ∼2 × 10-9 W/√Hz in the 0.29-0.38 THz range, in photovoltage and photocurrent mode. The potential of this technology for scalability to higher frequencies and the development of flexible devices makes our approach competitive for a future generation of THz detection systems.

Growth and Characterization of GaSb-Based Type-II InAs/GaSb Superlattice Photodiodes for Mid-Infrared Detection

InAs/GaSb superlattice (SL) midwave infrared photovoltaic detectors are grown by molecular beam epitaxy on GaSb(001) residual p-type substrates. A thick GaSb layer is grown under the optimized growth condition as a buffer layer. The detectors containing a 320-period 8ML/8ML InAs/GaSb SL active layer are fabricated with a series pixel area using anode sulfide passivation. Corresponding to 50% cutoff wavelengths of 5.0 mu m at 77 K, the peak directivity of the detectors is 1.6 x 10(10) cm.Hz(1/2) W-1 at 77 K.

Solid-core tellurite glass fiber for infrared and nonlinear applications

By optimizing glass composition and using a multistage dehydration process, a ternary 80TeO(2)-10ZnO-10Na(2)O glass is obtained that shows excellent transparency in the wavelength range from 0.38 mu m up to 6.10 mu m. Based on this optimized composition, we report on the fabrication of a single-mode solid-core tellurite glass fiber with large mode area of 103 mu m(2) and low loss of 0.24 similar to 0.7 dB/m at 1550 nm. By using the continuous-wave self-phase modulation method, the non-resonant nonlinear refractive index n(2) and the effective nonlinear parameter gamma of this made tellurite glass fiber were estimated to be 3.8x10(-1)9 m(2)/W and 10.6 W-1.m(-1) at 1550 nm, respectively. (C) 2009 Optical Society of America

金在酸性硫脲中的电化学行为

传统的金的提取方法都使用氰化法，氰化法有许多缺点，而硫脲是金的良好络合剂，在工业上已经受到普遍重视，自60年代以来，对于它在提取黄金的应用方面已经作了许多研究，但它在应用过程中的高消耗问题一直没能得到解决。黄金的浸取实际上是一个电化学过程，因而我们认为必需用电化学方法对金在酸性硫脲体系中的电化学行为进行研究，以促进硫脲在工业上早日应用。本论文主要是用循环伏安法和旋转园盘电极研究温度，硫脲浓度为及SO_2、H_2S对金在酸性Tu中的电化学过程的影响。一.循环伏安法：用经过循环扫描处理的Au电极在0.1M的H_2SO_4介质中的溶液作循环伏安图，发现，第一次扫描在0.75V左右处有一氧化峰，还原时有0.12V处有一相应的还原峰，第二次正向扫描时，在0.43V左右有一氧化峰，而在0.75V左右的氧化峰消失并从0.75V开始氧化电流迅速增大，经过恒电位电解证明在0.43V左右氧化峰是金的阳极溶解峰，在0.12V处的还原峰是Au(Tu)_2~+的还原峰，而第一次在0.75V左右的氧化峰具体是什么反应不清楚，但它对电极起了活化作用，若扫描上限低于0.75V，那么，经过多次的循环扫描也不出现金的阳极溶解峰和还原峰。随Tu浓度增大和温度升高，Epa不变，Ipa线性增大，而当浓度大于0.1M时有偏差。扫描上限达到1.1v时，Au电极表面也不出现表面氧化物的还原峰。二.旋转园盘电极 以较慢的扫描速度（4mv/s）对旋转金盘电极作单扫描曲线。没有得到极限电流，而得到一个电流峰，该阳极溶解峰电位随温度升高正移，随Tu浓度的增大负移，随转速的增大略有负移。1/i～1/w~(1/2)呈良好的线性关系，但在不同的电位下直线互不平行。显然，这种Au电极的轻微的钝化现象和Tu在Au电极表面上的反应特性有关。在同一电位下，通过变化Tu浓度而求得的表观反应级数是1.1～1.7之间。而变化温度求得的表观活化能随Tu浓度增大和电位升高而增大，这种反常现象是由于电极反应是一个与Tu在Au的表面上吸附有关的表面反应。随Tu浓度的增 大和电位变正均导致Au(tu)_(ad)~+的增多而使电极表面上充满着Au(tu)_(ad)~+，其结果是可以发生电化学反应的物质减少了。同时Tu的吸附也变得困难了，就导致了表观活化能的增加。并由此导出电极反应的机理是：Au＋Tu－－－－Au(tu)_(ad) （1） Au(tu)_(ad)－－－－ Au(tu)_(ad)~++e （2） Au(tu)_(ad)~++Tu－－－－Au~(tu)_2~+ （3） 这里步骤＜3＞是反应的控制步骤，而＜1＞和＜2＞处于准平衡状态。三.SO_2和H_2S对Tu溶金的影响 SO_2和H_2S对Tu溶Au有影响，SO_2在Au电极上的吸附能催化硫脲的溶金过程，而H_2S对硫脲的溶金过程起阻碍作用。四.金在硫脲衍生物中的电化学行为 丙烯基硫脲，氨基硫脲和二苯基硫脲是Tu的衍生物，丙烯基硫脲和Tu相似，能溶解金，但其电位比Tu体系稍正、氨基硫脲在Au电极上被氧化，它络合金的能力很差，而二苯基硫脲本身非常稳定，难和金发生作用。五.及化电阻法 用极化电阻法测定含有Fe~(3+)的Tu体系溶解金的极化阻力时发现，随Tu浓度和Fe~(3+)浓度的增加，极化阻力都减小了，但当Fe~(3+) 的浓度较大或刚开始加入Fe~(3+)时，金溶解的极化电阻随时间是降低的，一段时间后再随时间的延长而增大。

双色量子阱红外探测器大面阵芯片的研制

采用GaAs／AIGaAs和InGaAs／AIGaAs多量子阱，研制出了双色同像素读取结构的中波／长波量子阱红外探测器及160x128元中波／长波双色多量子阱红外探测器芯片。器件的材料结构生长是采用分子束外延技术，在5．08cm半绝缘GaAs衬底上完成的。发展了双色大面阵制备工艺。二维光栅的制备使用标准光刻和离子束刻蚀技术。在77K时，对量子阱红外探测器测试，得到中、长波段峰值探测率分别为Dλ=（1．61-1．90）x10~(10)cmHz~(1/2)W~-1和（1．54-2．67）x10^10cmHz~(1/2)W~-1)。中、长波段峰值波长分别为（2．7-3．8）μm和8．3μm。

低温生长GaAs在Nd:YVO4激光器中调Q特性的研究

采用一种新型的被动调Q饱和吸收体,低温生长GaAs薄膜,实现了半导体抽运Nd:YVO4激光器的调Q运转.研究了激光器的调Q特性,调Q抽运阈值为2W.在抽运功率9.2 W时,获得的最短脉冲半峰全宽为15 ns,最大单脉冲能量为4.84 μJ,最高峰值功率为330 W,最大平均输出功率为1.16 W;脉冲重复频率在220 kHz到360 kHz之间.

MOCVD生长InGaAs/InGaAsP多量子阱光泵微碟激光器

用MOCVD方法生长了InGaAs/InGaAsP多量子阱微碟激光器外延片，用光刻、干法刻蚀和湿法刻蚀等现代化的微加工技术制备出直径9.5μm的InGaAs/InGaAsP微碟激光器，并详细介绍了整个制备工艺过程。在液氮温度下用氩离子激光器泵浦方式实现了低阈值激射，测出单个微碟激光器的阈值光功率为150μW，激射波长约为1.6μm，品质因数Q=800，激射光谱线宽为2nm，同时指出微碟激光器射线宽比F-P普通激光器宽很多是由于其品质因数很高造成的。

GaAs/AlGaAs多量子阱二维面阵红外探测器

报道10×16元二维面阵GaAs/AlGaAs多量子阱红外探测器的研究进展。通过表面光栅耦合,采用垂直入射的工作模式,在T=80K时探测率为2.9×10~(10)cm·Hz~(1/2)/W,电压响应率为1.3×10~4V/W。各测试单元间探测率和电压响应率的偏差小于18％,串音小于0.45％,在最大探测率偏置条件下,器件的暗电流密度为6.2×10~(-6)A/cm~2。

Design and optimization of highly nonlinear low-dispersion crystal fiber with high birefringence for four-wave mixing

We have proposed a novel type of photonic crystal fiber (PCF) with low dispersion and high nonlinearity for four-wave mixing. This type of fiber is composed of a solid silica core and a cladding with a squeezed hexagonal lattice elliptical airhole along the fiber length. Its dispersion and nonlinearity coefficient are investigated simultaneously by using the full vectorial finite element method. Numerical results show that the proposed highly nonlinear low-dispersion fiber has a total dispersion as low as +/- 2.5 ps nm(-1) km(-1) over an ultrabroad wavelength range from 1.43 to 1.8 mu m, and the corresponding nonlinearity coefficient and birefringence are about 150 W-1 km(-1) and 2.5 x 10(-3) at 1.55 mu m, respectively. The proposed PCF with low ultraflattened dispersion, high nonlinearity, and high birefringence can have important application in four-wave mixing. (C) 2010 Optical Society of America

地下结构的爆炸振动效应与冲击破坏行为研究

对爆源近区地下混凝土管道结构在爆炸冲击载荷作用下的动力学响应开展探索性实验研究。选用钢筋混凝土管道模拟地下结构，尺寸为：$\phi_{\hbox{内}}$800mm$\times$2000mm$\times$100mm。通过实验研究定量确定爆炸振动波载荷对地下结构产生的振动效应；定性确定爆炸冲击波载荷对地下管道结构和混凝土材料产生的动态破坏效应。爆炸当量分别为50 g和100 g TNT，爆炸距离取为0.1，0.3，1，7和10m。实验主要涉及地下管道结构在小药量爆炸点近区的破坏效应与爆炸药量和爆炸距离间关系的确定；混凝土材料破坏行为与药量和爆炸距离关系的确定；爆炸冲击波的影响范围以及爆炸振动波的有效影响范围与爆源特性的关系及爆炸响应函数的确定。从小当量地下结构爆炸实验观察到：地下结构的爆炸振动响应，即振动波波长和频率不同于土介质地表的波长和频率。与地表面上建筑物的波长和频率相比，振动波长持续作用时间明显缩短，且振动频率显著提高。这与地下结构的爆炸动力学响应，特别是爆源近距离的结构动力学响应存在着本质的区别。不同的爆炸距离和当量，地下爆炸对地下结构可以产生振动和冲击两种不同特征的动力学效应。在折算距离大于0.22$\sim$0.25 m/W$^{1/3}$时，100 g TNT当量的爆炸以产生振动效应为主。在折算距离小于0.22$\sim$0.25 m/W$^{1/3}$时，爆炸主要产生冲击效应；在爆炸距离小于1.5m/W$^{1/3}$时，地下爆炸振动波对结构产生的动力学响应的明显特征是管道结构发生径向变形。而且，管道上与爆源最近点是管道变形的对称点。管道的轴向和环向动力响应表现为相应方向上的刚体振动。在爆炸距离大于1.5 m/W$^{1/3}$，如等于2.15m/W1/3的情况下，爆炸振动波对管道结构产生的动力学响应主要表现为整体振动。结构的变形特征基本消失；地下爆炸冲击波载荷对爆源近区管道结构和混凝土材料可以产生三种破坏效应：在折算距离等于0.065 m/W$^{1/3}$时，低强度的冲击波载荷仅产生结构破坏效应。实验中观察到混凝土管道只沿其轴线方向上形成贯穿性裂纹，管道内外表面均无损伤和破碎现象；当折算距离等于0.027 m/W1/3时，较强冲击波载荷既引起管道的结构破坏，也产生混凝土材料的破坏。这时观察到沿混凝土管道轴线方向上，以及与轴线成30$^\circ$至50$^\circ$范围内形成贯穿性裂纹。同时在管道内表面出现直径约为210 mm的层裂区，最大层裂厚度约为8$\sim$12 mm；当折算距离等于0.022 m/W$^{1/3}$时，爆炸强冲击波载荷主要引起的混凝土材料破坏形式表现为破碎。即在管道上以爆源最近点为中心形成直径约为370 mm的贯穿性孔洞，还观察到该孔洞周边不同方向上有长度为230$\sim$410 mm不等的数条细裂纹形成。