Design and fabrication of 1-D semiconductor nanomaterials for high-performance photovoltaics

To date, the cost-effective utilization of solar energy by photovoltaics for large-scale deployment remains challenging. Further cost minimization and efficiency maximization, through reduction of material consumption, simplification of device fabrication as well as optimization of device structure and geometry, are required. The usage of 1D nanomaterials is attractive due to the outstanding light coupling effect, the ease of fabrication, and integration with one-dimensional(1-D) semiconductor materials. The light absorption efficiency can be enhanced significantly, and the corresponding light-toelectricity conversion efficiency can be as high as their bulk counterparts. Also, the amount of active materials used can be reduced. This review summarizes the recent development of 1-D nanomaterials for photovoltaic applications, including the anti-reflection, the light absorption,the minority diffusion, and the semiconductor junction properties. With solid progress and prospect shown in the past 10 years, 1-D semiconductor nanomaterials are attractive and promising for the realization of high-efficiency and low-cost solar cells.     

增效磷—1号的研制和应用

本文报导了以酚类和烷基硫代磷酰氯酯为原料,在碱催化剂的存在下,以水溶剂直接反应成增效磷—Ⅰ号的工艺条件,产物收率达97—98%,并给出其对水胺硫磷的增效作用试验结果。     

长白山区次生林恢复过程中天然更新的动态

以长白山区天然次生林为研究对象,采用空间代替时间的方法,分别对不同年度进行择代后形成的天然次生林进行群落学调查,分析择伐后28年恢复期间高度小于3m的幼苗幼树的天然更新过程及特点。结果表明,恢复初期更新幼苗幼树的树种出现比率较低,随着次生林恢复时间的增加,更新幼苗幼树的树种出现比率超过75％,且15年后变化相对较小;次生林内更新幼苗幼树的分布密度随着恢复时间的增加呈增加的趋势,恢复15年时分布密度达7500株／hm^2,此后分布密度的变化相对较小;在次生林内幼苗幼树主要是集中分布在距最近立木1．5～3．5m的范围内,随着次生林恢复时间的增加,幼树的分布范围相对靠近立木,幼苗的分布范围则相对远离立木。     

郭守敬的《授时历》和朝鲜的《七政算内篇》

《授时历》被评价为中国历史上最优秀的历法,并且成为明朝《大统历》和朝鲜《七政算内篇》成书的基础。《七政算内篇》是朝鲜世宗时代(1418—1450年)取得的重要天文业绩之一,以《回回历》为基础,与《七政算外篇》一同于1444年编纂成书。《七政算内篇》的历元、天文常数和计算法等基本体系参照《授时历》,应数值则参照了《大统历》的辛巳应数。且把四余添加在推步的项目中,在计算日月食时使用的常数值则参考了元统1384年编纂的《大统历法通轨》,《七政算内篇》汲取了《授时历》和《大统历》的优点。     

韩国国立古宫博物馆世宗朝自击漏复原(英文)

自动时报漏刻(自击宫漏)是宫中都工匠护军蒋英实奉世宗大王(李祹,1397—1450年;1418—1450年在位)之命于1433年制造的。从1434年7月1日开始它成为国家的标准计时仪器。对民众报时的午正、人定和罢漏就是根据这套计时仪器报的。它安装在景福宫的报漏阁里,因此后称报漏阁漏.景福宫是国家天文台"简仪台"所在地。它能够通过操控声音和视觉信号发生系统依朝鲜时代的二元化时制——即十二时辰和五更点法——自动报时。系统自动发出报时声同时显示指示,报出十二时、百刻,以及五更时刻。世宗大王创制的报漏阁自击漏成为模型在朝鲜(1392—1910年)经历过3次复制或修复——1433年的初创,1536年的再创以及1618年的重创。初创之后574年,2004年为了纪念韩国国立古宫博物馆在首尔开馆,文化财厅,博物馆与建国大学校和自击漏硏究会签订了自击漏复原计划,到2007年11月展示了复原的自击漏。复原计划是按照《世宗实录.报漏阁记》中的记载以及原器物的一些残余部分——包括1536年和1618年仪器的现存部分——进行的。用了一年半的时间复制漏器和自击装置。文章从机械学和功能方面的细节系统地描述了复原的过程,包括根据当时的教范《漏筹通义》的记载刻制十一支箭.《漏筹通义》是根据授时历和经过汉阳(当时朝鲜首都)地方时校正的《七政算内篇》编纂的。自击漏包括4个主要部分:(1)漏器部,通过安排三级播水壶,用于两个受水壶递水的计时壶来计时;(2)方木机构,通过在相应的时间落下相应的小铜丸将水平面转换到以数字显示的二元报时时刻标示信号;(3)铁丸放出机构,由复杂的杠杆系统操纵的机构放大动力报时机来操作。(4)视听觉报时部,由两个次一级结构组成。一个是十二时辰报时机部,包括一个钟和木制的小雕像系统,以不同次数的敲钟声和相应的木制的十二支神小雕像举出的时辰牌来报时。另一个是更点机,包括一面鼓、一面锣、以及小雕像,小雕像在不同的更点敲击出相应次数的锣鼓声以报更点。我们对已经失传几个世纪的铁丸作动人形机构的详细复制表明,蒋英实受到了阿拉伯铁丸利用报时法的启发,发明了丸落下时刻标时法(通过落丸来标示时刻的机械装置),并通过改进13世纪阿拉伯时计师al-Jazari的仪器来实现将动力传到对人形机构的推动中。另一方面,苏颂的《新仪象法要》,《元史》中描述的郭守敬的大明殿灯漏以及顺帝的宫漏可能影响了世宗朝的宫廷学者。总的来说,这次复原源于对当时的文献记载和遗物的重建,中国-阿拉伯钟表技术对我们也很有帮助。全部系统现在运行良好。我们的复原将有助于重建古代东亚、甚至阿拉伯的机械水钟。     

利用杀菌剂防治松萎蔫病

松萎蔫病是一种非常复杂的病害。据报道,松材线虫(Bursaphelenchus xylophilus)及其携带的细菌诱导了该病,但是对于细菌的的作用尚存争议。笔者筛选出杀细菌剂进行了温室和林间防治松萎蔫病的实验。利用每株3年生赤松(Pinus densiflora)注射3 mg的恶喹酸,松萎蔫病防效达到71 %。利用恶喹酸或阿维菌素及两者混合物对大约20年生赤松的试验表明,3种处理均显示了很高的防效。以上结果证明伴生细菌是诱导松萎蔫病的必要因素,对松萎蔫病可利用杀细菌剂或杀细菌剂与杀线剂混合物进行防控。     

Polyreactivity increases the apparent affinity of anti-HIV antibodies by heteroligation

During immune responses, antibodies are selected for their ability to bind to foreign antigens with high affinity, in part by their ability to undergo homotypic bivalent binding. However, this type of binding is not always possible. For example, the small number of gp140 glycoprotein spikes displayed on the surface of the human immunodeficiency virus (HIV) disfavours homotypic bivalent antibody binding. Here we show that during the human antibody response to HIV, somatic mutations that increase antibody affinity also increase breadth and neutralizing potency. Surprisingly, the responding naive and memory B cells produce polyreactive antibodies, which are capable of bivalent heteroligation between one high-affinity anti-HIV-gp140 combining site and a second low-affinity site on another molecular structure on HIV. Although cross-reactivity to self-antigens or polyreactivity is strongly selected against during B-cell development, it is a common serologic feature of certain infections in humans, including HIV, Epstein-Barr virus and hepatitis C virus. Seventy-five per cent of the 134 monoclonal anti-HIV-gp140 antibodies cloned from six patients with high titres of neutralizing antibodies are polyreactive. Despite the low affinity of the polyreactive combining site, heteroligation demonstrably increases the apparent affinity of polyreactive antibodies to HIV.     

Germline-specific dgcr8 knockout in zebrafish using a BACK approach

Zebrafish is an important model to study developmental biology and human diseases. However, an effective approach to achieve spatial and temporal gene knockout in zebrafish has not been well established. In this study, we have developed a new approach, namely bacterial artificial chromosome-rescue-based knockout (BACK), to achieve conditional gene knockout in zebrafish using the Cre/loxP system. We have successfully deleted the DiGeorge syndrome critical region gene 8 (dgcr8) in zebrafish germ line and demonstrated that the maternal-zygotic dgcr8 (MZdgcr8) embryos exhibit MZdicer-like phenotypes with morphological defects which could be rescued by miR-430, indicating that canonical microRNAs play critical role in early development. Our findings establish that Cre/loxP-mediated tissue-specific gene knockout could be achieved using this BACK strategy and that canonical microRNAs play important roles in early embryonic development in zebrafish.