Effects of Nanostructures on the Fracture Strength of the Interfaces in Nacre

A strengthening mechanism arising from a type of inorganic nanostructure in the organic matrix layers is presented by studying the structural and mechanical properties of the interfaces in nacre. This nanostructural mechanism not only averagely increases the fracture strength of the organic matrix interfaces by about 5 times, but also effectively arrests the cracks in the organic matrix layers and causes the crack deflection in this biomaterial. The present investigation shows that the main mechanism governing the strength of the organic matrix interfaces relies on the inorganic nanostructures rather than the organic matrix. This study provides a guide to the interfacial design of synthetic materials.

利用本征脸方法减少冷原子云吸收成像照片中的干涉条纹

本征脸方法是广泛应用于人脸识别的一种图像处理方法，本文将其引入到原子芯片上囚禁的冷原子云吸收成像照片的图像处理中，以减少其中的干涉条纹，增加信噪比。本文首先介绍了吸收成像照片的标准处理方法以及干涉条纹的产生原因，由于参考照片和吸收成像照片中的干涉条纹会发生随机的相对变化，处理后干涉条纹难以消除。和标准的处理方法相比，本征脸方法不是使用1张而是50张参考照片，利用这些照片重构出一张新的参考照片，这张照片比那50张中的任何一张都更近似于吸收成像照片，因此和只使用1张参考照片相比，处理之后的干涉条纹对比度明显降

一种使用双棱镜的动态小角度测量方法

提出一种基于正切关系和相位调制技术的动态小角度测量方法。使用双棱镜组成干涉测量臂引导两束平行光至分束棱镜处干涉,通过提取携带被测信息的干涉信号的相位实现动态的小角度测量。由于采用位置探测器(PSD)对测量臂中两平行光束的间距进行测量,简化了测量方程,消除了装置中双棱镜必须对称放置的要求。通过正弦地改变半导体激光器的注入电流在时域内实现对干涉信号的相位调制,形成准外差干涉测量模式,提高了光程差的测量精度。实验验证了该方法的可行性,并讨论了影响小角度测量精度的误差因素。研究结果表明,基于该方法的动态小角度的重

农牧交错区不同植物群落的根冠比特征及土壤呼吸日动态的观测研究

本论文对草地群落地上/地下生物量构成、根冠比特征及其影响因子以及土壤呼吸测定方法比较等的国内外研究进展和主要成果进行了综述，在此基础之上对地处我国北方农牧交错带中段的内蒙古多伦县境内的18种草地群落（包括天然草地和人工草地群落）进行了相关内容的研究工作。 在2002年生长季期间，对这18个植物群落中选取的16个进行了群落学调查，测定了其地上、地下生物量，同时测定了土壤含水量、土壤容重、土壤全氮含量和土壤有机质含量。分别分析了地上、地下生物量以及根冠比（root to shoot ratio）与这些立地因子间的相关关系。同期，从18个群落中选定10个代表性群落测定其土壤呼吸速率，测定方法选用了动态红外气体分析法 (Infra red gas analysis， abbreviated as IRGA)和碱液吸收法（Alkali absorption, abbreviated as AA）。对这两种方法的测定结果进行了比较分析，同时分析了不同群落间土壤呼吸变化与土壤水分和养分状况等的相关关系。主要结论如下： ①16种植物群落的地上和地下生物量差异明显，地上生物量变化范围在80~500 g•m-2之间;相比之下，地下生物量的变化范围要大得多，16个群落中地下生物量最小的为猪毛菜群落，最大的为拂子茅群落，分别为533 g•m-2和2590 g•m-2。群落的根冠比在1.5～11.21之间，平均根冠比为 5.69。 ②土壤含水量对地上和地下生物量有着重要的影响，土壤含水量高的样地（羊草样地）较含水量低（小米蒿样地）的样地地上生物量高，反之亦然。但含水量与地下生物量之间的这种关系却不明显，即土壤含水量高的样地其地下生物量并不一定比含水量低的样地地下生物量高;根冠比与土壤含水量之间基本上呈负相关。土壤全氮含量和有机质含量与地上、地下生物量也存在着一定的正相关关系，而土壤容重却与生物量存有负相关关系;根冠比与土壤全氮、有机质和容重的关系正好与此相反，即根冠比与全氮和有机质含量呈负相关，与容重为正相关。 ③10种植物群落土壤呼吸的昼夜变化比较明显，均为单峰型曲线，主要受土壤温度的驱动，但同时也受到当日降水情况和云量、风速等气象因子的较大影响。因此，影响到这些群落土壤呼吸日动态的一致性，使得规律性并不明显。 ④用碱液吸收法和动态密闭气室法测定的10个群落的土壤呼吸速率变化范围分别为394~894mg C•m-2•d-1和313~2043 mg C•m-2•d-1，其中碱液吸收法测定结果平均为动态气室法的67.5%，明显低于动态密闭气室法。 ⑤两种测定方法具有很好的相关性，R2为0.8739。本研究中发现，在土壤呼吸速率低的情况下，两种方法的测定结果十分接近，甚至碱液吸收法的测定结果稍大于动态密闭气室法;而在土壤呼吸速率较高的情况下，动态密闭气室法测定结果则显著高于碱液吸收法。上述结果与国内外同类研究的结果高度一致，从而为校正我们以往采用碱液吸收法在该区域的测定结果提供了可靠依据。 ⑥各个群落间的土壤呼吸变化与立地土壤水分和土壤养分之间存有一定的相关关系，但并不显著，可能与这些群落土壤呼吸测定不是在同一天进行有关。

一种新型环状小肽BA及其应用

本发明涉及一种新型环状小肽BA及其应用，属于生物医学技术领域。本发明的环状小肽BA，分子量1259.56道尔顿，等电点4.44，具有一定的丝氨酸蛋白酶抑制剂活性，无酶活性。其全序列为：Cys Trp Thr Lys Ser Ile Pro Pro Lys Pro Cys(CWTKSIPPKPC)，第1位半胱氨酸和第11位的半胱氨酸形成分子内二硫键。该环状小肽BA作为药物设计模版及作为制备治疗肿瘤药物的应用。以环状小肽BA作为模版，在其氨基端和羰基端分别进行不同氨基酸的增加，得到具有抗菌活性或丝氨酸蛋白酶抑制剂活性的环状小肽BA1和环状小肽BA2，并作为制备治疗肿瘤、胃炎、胰腺炎药物的应用。本发明还具有序列简单、合成方便等优点。

A PCR-based RFLP analysis of Sarcocystis cruzi (Protozoa : Sarcocystidae) in Yunnan province, PR china, reveals the water buffalo (Bubalus bubalis) as a natural intermediate host

A polymerase chain reaction-based restriction fragment length polymorphism (RFLP) approach is used to examine Sarcocystis cruzi-like taxa from the atypical intermediate host, water buffalo, in Yunnan, People's Republic of China. The loci examined lie with

Transplantable neural progenitor populations derived from Rhesus monkey embryonic stem cells

Cell-based therapies using embryonic stem cells (ESCs) in the treatment of neural disease will require the generation of homogenous donor neural progenitor (NP) populations. Here we describe an efficient culture system containing hepatocyte growth factor (HGF) and G5 supplement for the production of highly enriched (88.3% +/- 8.1%)populations of NPs from rhesus monkey ESCs. Additional purification resulted in NP preparations that were 98% nestin positive. Moreover, NPs, as monolayers or neurospheres, could be maintained for prolonged periods of time in media containing HGF+G5 or G5 alone. In vitro differentiation and in vivo transplantation assays showed that NPs could differentiate into neurons, astrocytes, and oligodendrocytes. The kinds and quantities of differentiated cells derived from NPs were closely correlated with their niches in vivo. Glial differentiation was predominant in periventricular areas, whereas cells migrating into the cortex were mostly neurons. Cell counts showed that 2 months after transplantation, approximately 25% of transplanted NPs survived and 65% - 80% of the surviving transplanted cells migrated along the ventricular wall or in a radial fashion. Subcloning demonstrated that several clonal lines derived from NPs expressed nestin and differentiated into three neural lineages in vitro and in rat brains in vivo. In contrast, some subcloned lines showed restricted differentiation both in vitro and in vivo in rat brains. These observations set the stage for obtaining highly enriched NPs and evaluating the efficacy of NP-based transplantation therapy in the nonhuman primate and will provide a platform for probing the molecular mechanisms that control neural induction.

滇池红鳍原鲌生物学及对太湖新银鱼渔业的影响

太湖新银鱼是云南出口创汇的主要鱼产品。近几年来,种群数量呈上升趋势的红鳍原鮊,普遍被视为是导致太湖新银鱼产量大幅度下降的主要原因。研究结果表明,滇池中的红鳍原鮊当体长小子100mm时,食物以枝角类为主;体长100—130mm时,枝角类和虾各半;体长大于130mm时,以虾为主食,兼食水生昆虫和鱼类,其中太湖新银鱼在食物中仅出现2次,出现频率为0.45％。可见红鳍原鮊对太湖新银鱼的直接危害极小,而间接影响则在于食物的部分重叠。这一新的研究结果,已成为滇池渔业科学管理的依据之一。

Electroabsoorption-modulated laser light-source module using selective area growth for 10 Gb/s transmission

In this work, a novel light source of strained InGaAsP/InGaAsP MQW EAM monolithically integrated with DFB laser is fabricated by ultra-low-pressure (22 x 10(2) Pa) selective area growth ( SAG) MOCVD technique. Superior device performances have been obtained, sue h as low threshold current of 19 mA, output light power of about 7 mW, and over 16 dB extinction ratio at 5 V applied voltage when coupled into a single mode fiber. Over 10 GHz 3 dB bandwidth in EAM part is developed with a driving voltage of 3 V. After the chip is packaged into a 7-pin butterfly compact module, 10-Gb/s NRZ transmission experiments are successfully performed in standard fiber. A clearly-open eye diagram is achieved in the module output with over 8.3 dB dynamic extinction ratio. Power penalty less than 1.5 dB has been obtained after transmission through 53.3 km of standard fiber, which demonstrates that high-speed, low chirp EAM/DFB integrated light source can be obtained by ultra-low-pressure (22 x 102 Pa) SAG method.

Analysis of semiconductor microlasers with an equilateral triangle resonator by rate equations

Semiconductor microlasers with an equilateral triangle resonator (ETR) are analyzed by rate equations with the mode lifetimes calculated by the finite-difference time-domain technique and the Pade approximation. A gain spectrum based on the relation of the gain spectrum and the spontaneous emission spectrum is proposed for considering the mode selection in a wide wavelength span. For an ETR microlaser with the side length of about 5 mum, we find that single fundamental mode operation at about 1.55 mum can be obtained as the side length increases from 4.75 to 5.05 mum. The corresponding wavelength tuning range is 93 nm, and the threshold current is about 0.1 to 0.4 mA.