PCR-RFLP analysis of mitochondrial DNA ND5/6 region among 3 subspecies of common carp (Cyprinus carpio L.) and its application to genetic discrimination of subspecies

Mitochondrial DNA ND5/6 region was studied by PCR-RFLP analysis among ten representative strains belonging to three subspecies (Cyprinus carpio carpio, Cyprinus carpio haematopterus and Cyprinus carpio rubrofuscus) of common carp (Cyprinus carpio L.). A total of 2.4 kb fragment was amplified and subjected to restriction endonuclease analysis with nine restriction endonucleases subsequently. The results indicated that each subspecies owned one hyplotype and four restriction enzymes (Dde I, HaeIII, Taq I and Mbo I) produced diagnostic restriction sites which could be used for discriminating the three subspecies and as molecular genetic markers for assistant selective breeding of common carp.

Isolation by phage display and characterization of a single-chain antibody specific for O-6-methyldeoxyguanosine

New approaches of making single chain Fv antibodies against O-6-methyl-2'-deoxyguanosine (O(6)MdG) have been demonstrated by using the phage antibody display system. Using O(6)MdG as an antigen, 21 positive clones were identified by ELISA from this library, one of which, designated H3, specifically binds to O(6)MdG with high affinity. The H3 scFv antibody has an affinity constant (K-aff) of 5.94 x 10(11)(mol/L)(-1). H3 scFv has been successfully used to detect O-6 MdG in DNA hydrolyses from yeast or E. coli cells treated with a DNA methylating agent. To our knowledge, this is the first report of the selection of a specific scFv against DNA adducts. The results demonstrate the potential applications of the phage display technology for the detection of DNA lesions caused by mutagens and carcinogens.

Metamorphic InGaAs quantum wells for light emission at 1.3-1.6 mu m

Metamorphic InGaAs quantum well structures grown on GaAs reveal strong light emission at 1.3-1.6 mu m, smooth surface with an average roughness below 2 nm. and good rectifying I-V characteristics. Dark line defects are found in the QW Post growth thermal annealing further improves the luminescence efficiency but does not remove those dark line defects. Some challenges of epitaxial growth using this method for laser applications are discussed. (c) 2006 Elsevier B.V. All rights reserved.

A 5.6-mW Power Dissipation CMOS Frequency Synthesizer for L1/L2 Dual-Band GPS Application

This paper presents a wide tuning range CMOS frequency synthesizer for dual-band GPS receiver, which has been fabricated in a standard 0.18-um RF CMOS process. With a high Q on-chip inductor, the wide-band VCO shows a tuning range from 2 to 3.6GHz to cover 2.45GHz and 3.14GHz in case of process corner or temperature variation, with a current consumption varying accordingly from 0.8mA to 0.4mA, from a 1.8V supply voltage. The measurement results show that the whole frequency synthesizer costs a very low power consumption of 5.6mW working at L I band with in-band phase noise less than -82dBc/Hz and out-of-band phase noise about -112 dBc/Hz at 1MHz offset from a 3.142GHz carrier.

A Novel 0.72-6.2GHz Continuously-Tunable Delta Sigma Fractional-N Frequency Synthesizer

This paper presents a wideband Delta Sigma-based fractional-N synthesizer with three integrated quadrature VCOs for multiple-input multiple-output (MIMO) wireless communication applications. It continuously covers a wide range frequency from 0.72GHz to 6.2GHz that is suitable for multiple communication standards. The synthesizer is designed in 0.13-um RE CMOS process. The dual clock full differential multi-modulus divide (MMD) with low power consumption can operate over 9GHz under the worst condition. In the whole range frequency from 0.72GHz to 6.2GHz, the maximal tuning range of the QVCOs reaches 33.09% and their phase noise is -119d8/Hz similar to 124d8/Hz @1MHz. Its current is less than 12mA at a 1.2V voltage supply when it operates at the highest frequency of 6.2GHz.

多投影系统D-vision中双手6自由度力觉交互

D-vision系统(这里"D"有"Divide Screen"和"Duplex-Vision"双重含义)是一类基于PC机群的多投影虚拟现实系统(或简称多投影系统).给出D-vision系统中双手6自由度力觉交互的实现过程:在客户端协同控制两个力觉交互设备Spidar-G(Space Interface for Artificial Reality withGrip)实现双手协作交互,其次构造一个基于UDP的Socket类完成客户端和绘制服务器节点之间的通讯,传递跟踪球的位置、方向等信息;然后,通过分布绘制实现在大屏幕上无缝显示.最后实验结果表明:在D-vision系统中双手6自由度力觉交互是一种自然直观的人机交互方式.

黄土高原子午岭林区6个典型群落优势种的热值和养分特征

能量流动、物质循环和信息传递共同构成了生态系统三大功能。能量是维持生态系统功能与过程的动力,Jordan(1971)认为能量比干物质更能反映出群落对自然资源(特别是太阳能)的利用情况。Long(1934)率先用热值来表示植物所含能量的多少,此后关于植物热值的研究工作逐渐展开。我国的植物热值研究始于20世纪80年代(杨福囤等,1983;祖元刚等,1986),主要集中在海南(林益明等,2000)、福建(林益明等,2004)、广东(任海等,1999)和浙江(郝朝运等,2006)等热带亚热带植物群落以及内蒙古羊草草原(鲍雅静等,2003),但有关黄土高原地区的植被热值研究尚未见报道。子午岭林区是黄土高原主要的天然次生林区,其植被主要是在弃耕地基础上逐渐恢复起来的(邹厚远等,2002)。由于自然因素与人为因素的影响,子午岭的植被在恢复时间上存在较大差异,形成了处于不同演替阶段的各种植被群落类型。本研究选取的6个代表性植被群落分别是沙棘(Hippophae rhamnoides)群落、山杨(Populus davidiana)群落、白桦(Betula platyphylla)群落、油松(Pinus tabulaeform...

低分子量马来酸酐化聚丁二烯橡胶改性聚乙烯增韧尼龙6

尼龙6是世界上使用最广泛的工程塑料之一，由于尼龙6大分子链中含有酰胺键能形成氢键，使其具有强韧、耐磨、耐冲击、耐疲劳、耐腐蚀等优异的特性。但是尼龙6存在低温和干态冲击性能差，吸水性大等弱点，不能满足汽车、电子、机械等行业对材料高韧性的需求。利用橡胶和弹性体对尼龙6进行增韧已经取得了很大的成功，但无法解决成本较高且基体材料刚性损失过大这一难题。实践证明，具有硬核软壳结构核壳粒子在增韧半晶性高聚物时，可以有效提高橡胶的增韧效率，减少体系拉伸强度和模量的损失。然而具有这种结构的核壳粒子合成过程复杂，成本很高，工业应用前景很小；而用传统的反应增容方法原位制备核壳粒子时，由于橡胶分子量大，黏度高，流动性差等特点限制了在反应中原位生成核－壳结构粒子的效率，影响最终的增韧效果。本论文首次尝试用低分子量的马来酸酐化聚丁二烯橡胶通过反应挤出的方法接枝改性聚乙烯，对尼龙6进行增韧，利用聚丁二烯橡胶分子链上的马来酸酐基团和尼龙6分子链的端氨基反应，在尼龙6基体中原位形成以聚乙烯为核，聚丁二烯为壳的核壳粒子，结果得到了高韧性、良好刚性的改性尼龙6。 实验证实该含有双键的低分子量橡胶能够成功的接枝到聚乙烯分子主链上，由于橡胶的马来酸酐化程度很高（14wt%），在同尼龙6共混过程中大大提高马酐基团和尼龙6端氨基之间反应生成的接枝共聚物的效率，可以有效减小两相间的界面张力，改善聚乙烯在尼龙6基体中的分散。通过透射电镜观察共混物内部形态结构发现，共混体系中形成了以聚乙烯为核，橡胶为壳的核－壳结构粒子。这种核－壳粒子对尼龙6有良好的增韧效果。当聚丁二烯橡胶的含量仅为1.5wt%时，尼龙6的冲击强度可以达到1100J/m，而拉伸强度还能保持在47.3MPa。 通过对核壳增韧体系冲击断面和拉伸力学曲线的分析我们发现，由于增韧体系中能够形成软壳硬核的核－壳结构粒子，在外力作用下，由橡胶相构成的壳结构能在聚乙烯核与基体之间形成纤维结构，这种纤维结构不仅能够改变体系的应力状态，引发基体屈服，而且大大增强了分散相粒子同基体之间的界面强度，提高体系的刚性。同时，由于两相间纤维结构的存在，材料内部形成一个类似“物理交联”的网络，材料表现出类橡胶的弹性拉伸性能，没有明显的屈服。 传统的S. Wu的逾渗理论不能很好预测这种核壳增韧体系的性能。Corté 和Leibler的模型不仅考虑了基体树脂的特性（ , , ）,而且还将分散相粒子尺寸（d）也考虑了进去，更好地预测了体系的脆韧转变点。同时在基体树脂相同，且都能增韧的前提下，可以通过Corté 和Leibler模型中参数C（代表分散相粒子能够引发基体发生屈服的能力）的大小预测增韧体系程度的大小，C值越大，体系增韧效果越好。 通过对从上述增韧体系中抽提出的原位生成的PE-g-PB-g-PA6接枝共聚物的热力学和形貌分析发现，PA6链段被限制在宽50-70nm条带状连续结构中，其运动能力受到限制，因此在结晶过程中PA6嵌段的扩散速度降低。导致在通常的结晶速率条件下（10oC/min）结晶不完善，其结晶度﹑结晶温度﹑熔融温度都有所降低，形成以γ晶型为主的不完善结晶。由于在PE和PA6链段之间由一个短的柔性PB链段相连接，因此PA6链段不能同PE发生共结晶，作为连续相PE的结晶行为受到接枝共聚物的影响要小很多。 关键词：低分子量马来酸酐化聚丁二烯橡胶，聚乙烯，尼龙6，核－壳结构，增韧，受限结晶。