Narrow-channel-spacing 32-channel arrayed-waveguide-grating multiplexer with an innovative alignment method

A 32-channel 50-GHz spaced arrayed-waveguide grating with our innovative configuration has been designed and fabricated. The performance of the device has been fully tested by using a tunable laser light source, optical power meter, and polarization controller. The insertion loss (IS) of the device is 4.2 similar to 7.4 dB. The crosstalk is about -28 clB. The IS uniformity is less than 3.2 dB. With our configuration, the performance of the device has been enhanced effectively and the difficulty in alignment process has been decreased obviously. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

Carbonization process of Si(100) by ion-beam bombardment

The evolution of carbonization process on Si as a function of ion dose has been carried out by mass-selected ion-beam deposition technique. 3C-SiC layer has been obtained at low ion dose, which has been observed by reflection high energy electron diffraction and X-ray photoelectron spectroscopy (XPS). The chemical states of Si and carbon have also been examined as a function of ion dose by XPS. Carbon enrichment was found regardless of the used ion dose here, which may be due to the high deposition rate. The formation mechanism of SiC has also been discussed based on the subplantation process. The work will also provide further understanding of the ion-bombardment effect. (C) 2001 Published by Elsevier Science B.V.

Glass transition and crystallization process of hard magnetic bulk Nd60Al10Fe20Co10 metallic glass

Glass transition and crystallization process of bulk Nd60Al10Fe20Co10 metallic glass were investigated by means of dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electronic microscopy (SEM). It is shown that the glass transition and onset crystallization temperature determined by DMTA at a heating rate of 0.167 K/s are 480 and 588 K respectively. The crystallization process of the metallic glass is concluded as follows: amorphous alpha-->alpha' + metastable FeNdAl novel phase -->alpha' + primary delta phase-->primary delta phase + eutectic delta phase Nd3Al phase + Nd3Co phase. The appearance of hard magnetism in this alloy is ascribed to the presence of amorphous phase with highly relaxed structure. The hard magnetism disappeared after the eutectic crystallization of amorphous phase.

Spatial and Temporal Variation of LURR and Its Implication for the Tendency of Earthquake Occurrence in Southern California

Based on the theory of LURR and its recent development, spatial and temporal variation of Y/Y-c (value of LURR/critical value of LURR) in the Southern California region during the period from 1980 through March, 2001 was studied. According to the previous study on the fault system and stress field in Southern California, we zoned the Southern California region into 11 parts in each of which the stress field is almost uniform. With the time window of one year, time moving step of three months, space window of a circle region with a radius of 100 km and space moving step of 0.25 degree in latitude and longitude direction, the evolution of Y/Y-c were snapshot. The scanning results show that obvious Y/Y-c anomalies occurred before 5/6 of strong earthquakes considered with a magnitude of 6.5 or greater. The critical regions of Y/Y-c are near the epicenters of the strong earthquakes and the Y/Y-c anomalies occur months to years prior to the earthquakes. The tendency of earthquake occurrence in the California region is briefly discussed on the basis of the examination of Y/Y-c.

C-values of seven marine mammal species determined by flow cytometry

C-values, which estimate genome size, have puzzled geneticists for years because they bear no relationship to organismal complexity. Though C-values have been estimated for thousands of species, considerably more data are required in order to better understanding genome evolution. This is particularly true for mammals, in which C-values are known for less than 8% of the total number of mammalian species. Among marine mammals, a C-value has been estimated only for the bottlenose dolphin (Tursiops truncatus). Thus examination of additional species of marine mammals is necessary for comparative purposes. It will enable a better understanding of marine mammal genome evolution, and it is also relevant to conservation, because larger genome size has been linked to increased likelihood of extinction in some plant and animal groups. Our study presents C-values of seven marine mammal species, including five cetacean species that are endangered to varying degrees. Similarly to the results for other groups, our results suggest that larger genome size in cetaceans is related to an increased likelihood of extinction.

Experimental and numerical investigations on dissolution and recrystallization processes of GaSb/InSb/GaSb under microgravity and terrestrial conditions

The effects of gravity and crystal orientation on the dissolution of GaSb into InSb melt and the recrystallization of InGaSb were investigated under microgravity condition using a Chinese recoverable satellite and under normal gravity condition on earth. To investigate the effect of gravity on the solid/liquid interface and compositional profiles. a numerical simulation was carried out. The InSb crystal melted at 525 degrees C and then a part of GaSb dissolved into the InSb melt during heating to 706 degrees C and this process led to the formation of InGaSb solution. InGaSb solidified during the cooling process. The experimental and calculation results clearly show that the shape of the solid/liquid interface and compositional profiles in the solution were significantly affected by gravity. Under microgravity, as the Ga compositional profiles were uniform in the radial direction. the interfaces were almost parallel. On the contrary, for normal gravity condition, as large amounts of Ga moved up in the upper region due to buoyancy, the dissolved zone broadened towards gravitational direction. Also. during the cooling process, needle crystals of InGaSb started appearing and the value of x of InxGa1-xSb crystals increased with the decrease of temperature. The GaSb with the (111)B plane dissolved into the InSb melt much more than that of the (111)A plane. (C) 2000 Elsevier Science B.V. All rights reserved.

C离子注入Si中Si-C合金的形成及其特征

利用离子注入和高温退火的方法在Si中生长了C含量为0.6%-1.0%的Si_(1-x)C_x合金，研究了注入过程中产生的损伤缺陷，注入C离子的剂量及退火工艺对合金形成的影响，探讨了合金的形成机理及合金产生的应变分布的起因，如果注入的C离子剂量小于引起Si非晶化的剂量，退火过程中注入产生的损伤缺陷容易与C原子结合形成缺陷团簇，难于形成Si_(1-x)C_x合金，而预先利用Si离子注入引进损伤有利于Si_(1-x)C_x合金的形成；但如果注入的C离子可以引起Si的非晶化，预先注入产生的损伤缺陷不利于Si_(1-x)C_x合金的形成。与慢速退火工艺相比，快速热退火工艺有利于Si_(1-x)C_x合金的形成。离子注入的C原子在空间分布不均匀，退火过程中将形成应变不同的Si_(1-x)C_x合金区域。

Reducing HAuCl4 by the C-60 dianion: C-60-directed self-assembly of gold nanoparticles into novel fullerene bound gold nanoassemblies

The C-60 dianion is used to reduce tetrachloroauric acid (HAuCl4) for the first time; three-dimensional C-60 bound gold (Au-C-60) nanoclusters are obtained from C-60-directed self-assembly of gold nanoparticles due to the strong affinities of Au-C-60 and C-60-C-60. The process was monitored in situ by UV-vis-NIR spectroscopy. The resulting Au-C-60 nanoclusters were characterized using transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy-dispersive spectroscopy (EDS), x-ray powder diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and FT-IR and Raman spectroscopies.

中国北方草本植物及表土有机质碳同位素组成

Recently, more and more attention has been paid to stable isotope ratios in terrestrial depositional systems. Among them, δ~(13)C value is mainly determined by the surface vegetation, while vegetation is directly related to climate, therefore, carbon isotope ratio in soil organic matter and pedogenic carbonate has been employed as an important paleoecological indicator. In order to test the paleoecological information extracted from stable isotope ratios in terrestrial depositional systems, it is necessary to study the relationships between δ~(13)C value in standing terrestrial plants and today climate, as well as between δ~(13)C value in modern surface soil organic matter and standing vegetation. Thus, these relationships were studied in this paper by means of analysing δ~(13)C in standing plants and modem surface soil organic matter in North China. The main results and conclusions are presented as following: 1. According to their δ~(13)C values, 40 C-4 species represent about 16% of the 257 plant species sarnpled from the North China. C-4 photosynthesis mainly occurs in Poaceae, Cyperaceae and Chenopidaceae families, and percentage representation of C-4 photosynthesis is up to 56% in Poaceae family. 2. The δ~(13)C values of C-3 plant species in North China vary from -21.7‰ to -32.0‰ with an average of -27.1‰, and 93% focus on the range of -24.0‰ ～ -30.0‰; δ~(13)C values of C-4 plant species in North China are between -10.0‰ ～ -15.5‰ with an average of -12.9‰, and 90% concentrate on the range of -11.0‰ ～ -15.0‰. 3. The δ~(13)C composition of C-3 plant species collected from Beijing, a semi-moist district, mainly vary between -27.0‰ ～ -30.0‰, and the average is -28.7‰; the δ ~(13)C values of plants in the semi-arid district, east and west to the Liu Pan Moutain, focus on the range of-26.0‰ ～ -29.0‰ and -25.0‰ ～ -28.0‰, respectively, with the mean value of -27.6‰ and -26.6‰, respectively; the δ~(13)C composition in the arid district dominantly vary from -24.0‰ to -29.0‰, with the average of -26.2‰, and among them, the δ~(13)C values of C-3 plant species in deserts are often between - 22‰ ～ -24‰; the δ~(13)C values in the cold mountain district concentrate on the range of -24.0‰ to -29.0‰, with the average of -26.3‰. 4. The main range of δ~(13)C composition of C-4 plant species, derived from Beijing, a semi-moist district, are -13.0‰ ～ -15.5‰; the semi-arid district, -11.0‰ ～ -14.0‰; the arid district, -11.0‰ ～ -14.0‰. The mean values of them are -14.0‰, -12.4‰,-12.7‰, respectively. 5. From east to west in North China, δ~(13)C values of C-3 plant species increase with longitude. The correlation between δ~(13)C ratios of C-3 plant species and longitude is linear. Changing temperate and precipitation and changing atmosphere pressure are spossible explanations. 6. Almost all C-3 plant species have the trends that their δ~(13)C values gradually increase with decreasing precipitation, decreasing temperature and increasing altitude. Our results show the increases of the δ~(13)C value by 0.30 ～ 0.45‰, 0.19 ～ 0.27‰ and 1.1 ～ 1.2‰ per 100 mm, I℃ and 1000 m, respectively, for all C-3 plant species together. 7. The δ~(13)C values of all C-3 plant species together and a part of C-3 species show highly significant linear correlation with the mean annual temperature, the mean annual precipitation and the altitude, and the results suggest that they can be used as proxies of these environmental variables, while, those without highly significant correlation, may be not suitable as the proxies. 8. The extent, which of responses of δ~(13)C composition to environmental variables, is different for each C-3 plant specie. 9. The δ~(13)C variations along altitude and longitude may be non-linear for C-4 p1ant species in North China. The mean annual temperature may be not important influential factor, thus, it suggests that the δ~(13)C composition of C-4 plant species may be not suitable as the proxy of the mean annual temperature. The influences of summer temperature on δ~(13)C values are much bigger than that of annual temperature, among them, the influence of September temperature is biggest. The mean annual precipitation may be one of the dominant influential factors, and it shows a highly significant non-linear relationship with δ~(13)C values, and the result indicates that δ~(13) C composition of C-4 plant species can be employed as the proxy of the mean annual precipitation. 10. The variations of δ~(13)C ratios do not show systematic trends along longitude, latitude and altitude for modern surface soil organic in Northwest China. ll. The δ~(13)C ratios of modern surface soil organic do not exhibit systematic patterns with temperature and precipitation in Northwest China, it suggests that, unless soil organic is transferred from pure C-3 or C-4 vegetation, the δ~(13)C composition of soil organic may be not used as proxies of climatic variables. 12. The δ~(13)C values of modem surface soil organic are heavier than that of standing vegetation, and the difference ofrnean δ~(13)C between them is -2.18‰. 13. Without considering the δ~(13)C difference between vegetation and soil organic, as well as the δ~(13)C drift in various enviromnent, we may not obtain the valuable information of C-3, C-4 relative biomass in vegetation. 14. The C-4 biomass contribution in vegetation increase with decreasing latitude, increasing longitude and decreasing altitude in Northwest China. The C-4 biomass almost are zero in those regions north to 38 ° N, or west to 100°E, or above 2400 m. 15. The C-4 relative biomass in vegetation increase with growing temperature and precipitation. and, C-4 plants are rare at those regions where the mean annual temperature is less 4 ℃, or the mean annual precipitation is less 200 mm, and their biomass contribution in vegetation are almost zero. Both the mean annual temperature and the mean annual average precipitation may be the important influential factors of C-4 distribution, but the dominant factors.

Effect of humidity on microstructure and properties of YBCO film prepared by TFA-MOD method

Epitaxial YBCO superconducting films were deposited on the single crystal LaAlO3 (001) substrate by metal organic deposition method. All YBCO films were fired at 820 degrees C in humidity range of 2.6%-19.7% atmosphere. Microstructure of YBCO thin films was analyzed by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). Superconducting properties of YBCO films were measured by four-probe method. XRD results showed that the second phase (such as BaF2)and a-axis-oriented grains existed in the films prepared at 2.6% humidity condition; a-axis-oriented grains increased in the film prepared at higher than 4.2% humidity condition; almost pure c-axias-oriented grains existed in the films fired at 4.2% humidity condition. Morphologies of the YBCO films showed that all films had a smooth and crack-free surface. YBCO film prepared at 4.2% humidity condition showed J(c) value of 3.3 MA/cm(2) at 77 K in self-field.

Effects of annealing on microstructure and optical properties of TiO2 sculptured thin films

The evolution of microstructure and optical properties of TiO2 sculptured thin films under thermal annealing is reported. XRD, field emission SEM, UV-Vis-NIR spectra are employed to characterize the microstructural and optical properties. It is found that the optimum annealing temperature for linear birefringence is 500 degrees C. The maximum of transmission difference for linear birefringence is up to 18%, which is more than twice of that in as-deposited thin films. In addition, the sample annealed at 500 degrees C has a minimum of column angle about 12 degrees C. The competitive process between the microstructural and optical properties is discussed in detail. Post-annealing is a useful method to improve the linear birefringence in sculptured thin films for practical applications.

洱海四种鲤鱼线粒体DNA遗传相似性的初步研究

用6种限制性内切酶对洱海的四种鲤鱼--洱海鲤(C. barbatus)、春鲤(C. longipectoralis)、大眼鲤(C. megalophthalmus)和杞麓鲤(C. carpio chila),其中前三种为洱海特有,进行了线粒体DNA(mtDNA)的限制性片段长度多态性(RFLP)分析,构建了它们的mtDNA限制性内切酶图谱。结果表明,这四种鲤鱼在种内和种间均缺乏mtDNA RFLP。这种现象在鱼类种间的mtDNA的RFLP研究中是罕见的。分析这一现象的原因,可能在于这些物种是同域形成物种,并且其分化时间还相当短。

带复杂数据结构的模型检测工具

模型检测是近二十几年来最成功的自动验证技术之一,而模型检测工具的开发是将模型检测和实际相结合的关键.为了有效地对涉及到复杂数据类型的并发传值系统进行模型检测,总结了以扩展的带赋值符号迁移图和模态图分别作为并发系统和逻辑公式的语义模型来实现模型检测工具的工作,特别是将复杂数据结构引入传值进程定义语言和带赋值符号迁移图.同时结合实际例子说明模型检测工具的有效性.

有机化合物结构解析专家系统研究——空间立体异构体的穷举生成

有机化合物结构解析专家系统的研究一直是计算机化学领域的前沿课题。本文在ESESOC 系统已有的基础上，进行了空间立体异构体的结构穷举生成研究，可以从化合物的二维连接表出发，穷举生成出全部的立体异构体。立体异构体的穷举生成需要满足三个条件：穷举性、非冗余性和有效性。目前本系统对于含 C、N、P、S与Si 等元素由于不对称中心、不对称轴引起的立体异构和几何异构均能进行穷举生成。本系统得到的结果与著名的 DENDRAL 系统和 SEMSMI 系统的结果完全一致。而 DENDRAL 系统已经从理论上证明是正确的。关于效率问题，通过对自同构群算法的改进，本系统的生成速度快于SEMAMI系统（其它系统运行时间未见报道），完全能够满足实验室应用。结构解析系统中环的识别主要是所有环的识别以及SSSR（最小的小最环集合）的识别，通过图论算法的应用，本文对这几类环的识别算法都进行了探讨，并应用于 ESESOC 系统作为约束条件，大大减少了系统候选化合物的数目。芳香性的识别，特别是稠环化合物芳香性的识别，在结构解析专家系统中一直是很难解决的问题，主要是稠环芳香性化合物的共振式比较多，而且在结构解析系统中得到的哪种共振式事先并不能确知，本文对各类常见的芳香性进行了自动识别的研究，并应用于 ESESOC系统中，取得了良好的结果。

分子束外延生长Al掺杂n型ZnS_（1-x）Tex的类DX中心

应用光致发光(PL)、电容-电压(C-V)、深能级瞬态谱(DLTS)和光电导(PC)技术系统研究Al掺杂ZnS_(1-x)Te_x中与Al有关的类DX中心。实验结果表明，ZnS_(1-x)Te_x中存在与Ⅲ－Ⅴ族半导体DX中心相类似的性质。获得与Al有关的类DX中心光离化能E_i(～1.0eV和2.0eV)和发射势垒E_e(0.21eV和0.39eV)，这表明ZnS_(1-x)Te_x大晶格弛豫的出现是由类DX中心引起。