Growth and spectral properties of Gd2SiO5 crystal codoped with Er and Yb

Gd2SiO5 (GSO) single crystal codoped with Yb3+ and Er3+ (Abbr. as Er:Yb:GSO) was successfully grown by the Czochralski (CZ) method for the first time and the spectral characteristics were investigated. The absorption and fluorescence spectra were measured. The emission lifetime of the I-4(13/2)-Er-level was measured to be 5.84ms and the emission cross-section at 1529nm was calculated to be 1.03 x 10(-20) cm(2). The results indicate that Er:Yb:GSO is a potential laser material at similar to 1. 55 mu m wavelength region. (c) 2006 Elsevier B.V. All rights reserved.

气相传输平衡法在（11-20）面蓝宝石上制备γ铝酸锂膜

为了寻找可能替代蓝宝石作为氮化镓外延的新型衬底，通过48h的气相传输平衡，分别在1000℃、1030℃、1050℃、1070℃和1100℃制备了一层单相多晶的γ铝酸锂膜。X射线衍射和扫描电镜分别用于表征膜的物相、取向和表面形貌。结果显示，γ铝酸锂择优取向的好坏取决于气相平衡传输温度，在1050℃制备的γ铝酸锂具有高度的[100]择优取向；在γ铝酸锂（001）面上的双轴拉应力可能有助于[100]择优取向的形成；γ铝酸锂晶粒表面裂纹的方向一致性与其择优取向紧密相关。上述结果表明在合适的工艺条件下，气相传输平衡

云南黄牛和大额牛的mtDNA多态性研究

云南黄牛有两种类型的mtDNA分子, 一种是普遍黄牛类型, 另一种是瘤牛类型, 两者的频率 分别为33%和67%。没有发现过渡型和重组型。昆明黑白花奶牛的mtDNA与云南黄牛的相关似 。云南黄牛可能具有两种起源, 即普通黄牛起源和瘤牛起源。今天的云南黄牛群体是这两种类型的混合。大额牛的限制性类型与瘤牛相同, 表明大额牛的起源与瘤牛有密切关系。图2 表1参18

温度对武汉东湖近邻剑水蚤发育及繁殖的影响

近邻剑水蚤完成一个世代所需的时间随不同的温度而有差别,在一定的温度范围内,其时间与温度呈正相关,在6.5℃时为64.3天,20℃时仅为20.2天,当25℃时则发育减慢。

20种鲤科鱼类同工酶的表型分析及有关进化问题的探讨

本文对20种鲤科鱼类的同工酶表型进行了分析比较。鲌亚科中存在几种不同的LDH同工酶表型,以各种LDH同工酶表型所组成的一些类群,反映出亚科水平中属间的亲缘关系。按同工酶的表型可将它们分为4个类群,这些类群的划分和进化趋异的过程是与经典的系统分类相一致的。按LDH同工酶表型的异同可将鲌亚科、密鲴亚科和鲢亚科的鱼类划分成两个主要的支系。一支鱼类是具有相同迁移率的LDH-A-4 同工酶,其中包括鲌亚科的多数鱼类,由LDH 同工酶的表型推断它们与雅罗鱼亚科有较密切的亲缘关系;另一支鱼类则是具有相同迁移率的 LDH

Short-term effects of drawing water for connectivity of rivers and lakes on zooplankton community structure

During 28-29, September 2005, water was drawn from Hanjiang River and Houguan Lake to the Yangzi River via Sanjiao Lake and Nantaizi Lake in Wuhan in order to provide favorable conditions for ecosystem restoration. To evaluate the feasibility and validity of drawing water as a means of ecosystem restoration, zooplankton populations were studied 3 times (before, immediately after finishing and a month after drawing water) at seven locations from 27 Sept. 2005 to 2 Nov. 2005. Water quality in the lakes was mostly improved and zooplankton species richness decreased as soon as drawing water had finished but increased a month after drawing water. Zooplankton density and biomass was reduced in the lakes by drawing water but was increased at the entrance to Sanjiao Lake because of landform geometry change. Before drawing water, most species in Sanjiao Lake e.g., Brachionus sp. and Keratella sp. were tolerant of contamination. After drawing water oligotrophic-prone species such as Lecane ludwigii and Gastropus stylifer emerged. We conclude that drawing water could be important for improving water quality and favour ecosystem restoration. Dilution of nutrient concentrations may be an important role in the effect.

Growing 20 cm Long DWNTs/TWNTs at a Rapid Growth Rate of 80-90 mu m/s

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-04-13T16:03:37Z No. of bitstreams: 1 Growing 20 cm Long DWNTsTWNTs at a Rapid Growth Rate of 80-90 mu ms .pdf: 3229914 bytes, checksum: 0259795afb443dc6901c11df5ecd325a (MD5)

n-type Ge-SiGe quantum cascade structure utilizing quantum wells for electrons in the L and Gamma valleys

In this letter, we propose an n-type vertical transition bound-to-continuum Ge-SiGe quantum cascade structure utilizing electronic quantum wells in the L and F valleys of the Ge layers. The optical transition levels are located in the quantum wells in the L valley. Under a bias of 80 kV/cm, the carriers in the lower level are extracted by miniband transport and L - Gamma tunneling into the subband in the Gamma well of the next period. And then the electrons are injected into the upper level by ultrafast intervalley scattering, which not only effectively increases the tunneling rate and suppresses the thermal backfilling of electrons, but also enhances the injection efficiency of the upper level. The performance of the laser is discussed.

Mode characteristics of semiconductor equilateral triangle microcavities with side length of 5-20 mu m

Semiconductor equilateral triangle microresonators (ETRs) with side length of 5, 10, and 20 mum are fabricated by the two-step inductively coupled plasma (ICP) etching technique. The mode properties of fabricated InGaAsP ETRs are investigated experimentally by photoluminescence (PL) with the pumping source of a 980-nm semiconductor laser and distinct peaks are observed in the measured PL spectra. The wavelength spacings of the distinct peaks agree very well with the theoretical longitudinal mode intervals of the fundamental transverse modes in the ETRs, which verifies that the distinct peaks are corresponding to the enhancement of resonant modes. The mode quality factors are calculated from the width of the resonant peaks of the PL spectra, which are about 100 for the ETR with side length of 20 mum.