Microstructure and characteristics in the organic matrix layers of nacre

The direct observation of a type of microstructure in the organic matrix layers of nacre was obtained with a transmission electron microscope. The microstructure, which is referred to as mineral bridge in the biomineralization, is nanoscale and randomly distributed in the layers. Statistical analysis gives the distribution laws and characteristics of mineral bridges in the organic matrix layers. The existence of mineral bridges in nacre was confirmed, and it was shown that the microarchitecture of nacre should be described as a "brick-bridge-mortar" arrangement rather than traditional "brick and mortar" one.

Formation Mechanism of Cracks in Saturated Sand

The formation mechanism of “water film” (or crack) in saturated sand is analyzed theoretically and numerically. The theoretical analysis shows that there will be no stable “water film” in the saturated sand if the strength of the skeleton is zero and no positions are choked. It is shown by numerical simulation that stable water films initiate and grow if the choking state keeps unchanged once the fluid velocities decrease to zero in the liquefied sand column. The developments of “water film” based on the model presented in this paper are compared with experimental results.

铸态SiCp／Al复合材料原位拉伸细观损伤的研究

本文运用带拉伸台的扫描电镜（ＳＥＭ），观察铸态ＳｉＣｐ／６０６１Ａｌ复合材料裂纹生成，裂纹扩展以及断口形貌。指出该材料损伤破坏的主要原因是由于粒子与基体脱粘，粒子团聚和大量存在的枝晶开裂造成的。提出了改善塑性加工性能和断裂韧性的方法。

Relay lens-free birefringence-customized stackable beam-steering modules for optical interconnects

A previously suggested birefringence-customized modular optical interconnect technique is extended for lens-free relay operation. Various lens-free relay imaging models are developed. We claim that the lens-free relay system is important in simplifying an optical interconnect system whenever the imaging conditions permit. To verify the validity of various proposed concepts, we experimentally implemented some 8 x 8 optical permutation modules. High-power efficiency and low channel cross talk were experimentally observed. In general, the larger the channel spacing, the less the cross talk. A quantitative cross-talk measurement of the lens-free relay system shows that, for a fixed channel width of 0.5 mm and channel spacings of 0.5, 1, and 2 mm, a less than -20-dB cross-talk performance can be guaranteed for lens-free relay distances of 40, 280, and 430 mm, respectively. (C) 1998 Optical Society of America.

国产贝母属（百合科）的系统学研究

作者通过实地调查，栽培观察，大量查阅标本，对国产贝母属(Fritillaria L.)的形态性状作了深入的分析，认为贝母属中植株大小，茎生叶先端卷曲与否，花的数目、花梗的长短、花被片颜色等性状易受生境的影响;而鳞茎所具鳞片的数目，植株最下一轮叶的形状及排列，花部蜜腺的形状，花柱柱头的分裂程度，雄蕊花丝在发育完后的长短，蒴果的形状等性状受生境的影响较小，但在栽培情况下，这些性状有时也会发生变化．此外，作者首次报道了部分国产贝母属种类的核型和花粉形态．在此基础上对我国贝母属进行了系统整理，将正式发表的138个分类名称（包括80个种、52个变种、5个变型、1个栽培变型）归并成24种l变种，并对国产贝母组(Seclion Fritillaria)的种间关系作了初步探讨;同时，对该属的次级分类也作了修订．根据有关，F.karelinii花粉学和细胞学资料，以及邻近4个种的形态特征及分布特点，我们支持J.G..Baker(1874)的观点将该类群保留在贝母属内而不同意A.S.Lozin-Lozinskaya(1935)，A.Takhtajan(1987)将其单立成属也不同意W.B.Turrill &J.R.Sealy(1980)将其并入贝母组(Sect.Fritillaria)，而将该类群做为贝母属中的一个新组——砂贝母组(Sect.Rhinopetalum (Fish. ex Alex.) Y.B.Luo)．并认为该组与贝母组关系较近．作者通过上述工作及查阅世界各地有关贝母属的文献，认为贝母属内最原始的类群是Sect. Fritillaria，而Sect.Petillium，Sect.Rhinopetalum和Sect.Theresia是演化水平中等的类群．Sect.Liliorhiza则是演化水平最高的一类．通过对该属组(Section)级及种级分布式样的分析，认为伊朗一土兰区不仅是组的多度中心，并且也是多样化中心;在种级水平上，地中海区是分布的多度中心，而种级多样化中心则在伊朗一土兰区;此外，在伊朗一土兰区还保留着一些较原始的类群，因而，该区可能是贝母属的起源中心，最后，作者对贝母属的起源时间、散布途径及现代分布格局形成的原因进行了初步探讨．

湖南产五步蛇蛇毒磷脂酶A_2的热稳定性

本文测定了湖南产五步蛇蛇毒磷脂酶Ａ２在不同温度保温后的酶活性，结果表明此酶具有一定的热稳定性。

高黎贡山地区公众保护意识教育

云南西部高黎贡山地区生物多样性既丰富又受威胁。当地公众不珍惜自然、无保护常识。为拯救该地区生物资源，笔者深入基层山区村户、不拘形式或小型非正式座谈讨论方式，对１０００余人进行了公众保护意识教育，使他们懂得了生物资源的保护与持续利用益在自身和长久，控制狩猎和择猎以确保野生动物种群稳定，改变“刀耕火种”、以计划限量采伐维护森林环境等。文中对未来公众保护教育提出了建议

土壤硒污染对土壤酶的生态毒理效应

通过室内培养和盆栽试验,研究了Se对黄棕壤过氧化氢酶、脱氢酶、脲酶、碱性磷酸酶、转化酶的生态毒理效应.结果表明,土壤Se对脱氢酶、碱性磷酸酶、转化酶有“抗性酶活性”现象.土壤Se对土壤过氧化氢酶和脲酶活性有抑制作用,脲酶受Se的抑制作用最强.土壤Se含量与脲酶抑制率之间具有显著相关性,脲酶抑制率可作为Se生态风险评价的一项生物指示物.

New type of multimode-interference-type thermo-optic variable optical attenuator

A thermo-optic variable optical attenuator (VOA) based on a Mach-Zehnder interferometer and multimode-interference coupler is fabricated. Not a single-mode but a multimode waveguide is used as the input and output structures of the optical field, which greatly reduces the coupling loss of the VOA with a normal single-mode fiber. The insertion loss of the fabricated VOA is 2.52 to 2.82 dB at the wavelength of 1520 to 1570 nm. The polarization dependent loss is 0.28 to 0.45 dB at the same wavelength range. Its maximum attenuation range is up to 26.3 dB when its power consumption is 369 mW. The response frequency of the fabricated VOA is about 10 kHz. (C) 2004 Society of Photo-Optical Instrumentation Engineers.

Lossless electroabsorption modulator monolithically rntegrated with a semiconductor optical amplifier and dual-wavegulde spot-size converters

Semiconductor optical amplifier and electroabsorption modulator monolithically integrated with dual-waveguide spot-size converters at the input and output ports is demonstrated by means of selective area growth, quantum-well intermixing, and asymmetric twin waveguide technologies. At the wavelength range of 1550 similar to 1600 nm, lossless operation with extinction ratios of 25-dB dc and 11.8-dB radio frequency and more than 10-GHz 3-dB modulation bandwidth is successfully achieved. The output beam divergence angles of the device in the horizontal and vertical directions are as small as 7.3 degrees x 10.6 degrees, respectively, resulting in 3.0-dB coupling loss with cleaved single-mode optical fiber.

Effect of rapid thermal annealing and hydrogen plasma treatment on the microstructure and light-emission of silicon-rich oxide film

Silicon-rich silicon oxide (SRSO) films are prepared by plasma-enhanced chemical vapor deposition method at the substrate temperature of 200degreesC. The effect of rapid thermal annealing and hydrogen plasma treatment on tire microstructure and light-emission of SRSO films are investigated in detail using micro-Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy and photoluminescence (PL) spectra. It is found that the phase-separation degree of the films decreases with increasing annealing temperature from 300 to 600degreesC, while it increases with increasing annealing temperature from 600 to 900degreesC. The light-emission of the films are enhanced with increasing annealing temperature up to 500degreesC, while it is rapidly reduced when the annealing temperature exceeds 600degreesC. The peak position of the PL spectrum blueshifts by annealing at the temperature of 300degreesC, then it red-shifts with further raising annealing temperature. The following hydrogen plasma treatment results in a disproportionate increase of the PL intensity and a blueshift or redshift of the peak positions, depending on the pristine annealing temperature. It is thought that the size of amorphous silicon clusters, surface structure of the clusters and the distribution of hydrogen in the films can be changed during the annealing procedure. The results indicate that not only cluster size but also surface state of the clusters plays an important role in the determination of electronic structure of the amorphous silicon cluster and recombination process of light-generated carriers.

Fabrication of luminescent Ge nanocrystals started from unlayered hydrogenated amorphous SiGe films or hydrogenated amorphous Si hydrogenated amorphous Ge multilayers

Nanocrystalline Ge embedded in SiOx matrix is fabricated by oxidizing hydrogenated amorphous Sice alloys or hydrogenated amorphous Si/hydrogenated amorphous Ge multilayers. The structures before and after oxidation are systematically investigated. Visible light emission was observed from both samples. The luminescence peak is located at 2.2 eV which is independent of the starting materials. Compared to the luminescence from unlayered samples, the photoluminescence spectrum from multilayered samples has a narrower band width, which can be attributed to the uniform size distribution. The light emission origin is also discussed briefly and a mechanism different from the quantum size effect is suggested.

基于Venn图的层次信息可视化

为解决具有层次结构的大量信息的可视化问题,文中给出了用嵌套圆表达树型结构信息的可视化方法,即用相切的圆表示兄弟节点,嵌套的圆表示父子节点,圆的位置、大小和颜色分别表示树节点的不同属性信息.同层的兄弟节点并排排列,圆的排列算法快速、稳定、紧密且不相互重叠,排列圆的个数与时间呈线性关系,该排列算法适于大量信息的可视化,既能快速显示大数据集的整体视图,又方便查看细节信息;既能清楚地表达复杂信息间的层次关系,又能显示树节点的属性.该方法可用于文件系统的可视化,实例表明该方法简单、实用、高效、可靠.