Energy gaps in "metallic" single-walled carbon nanotubes

Metallic single-walled carbon nanotubes have been proposed to be good one-dimensional conductors. However, the finite curvature of the graphene sheet that forms the nanotubes and the broken symmetry due to the local environment may modify their electronic properties. We used low-temperature atomically resolved scanning tunneling microscopy to investigate zigzag and armchair nanotubes, both thought to be metallic. "Metallic" zigzag nanotubes were found to have energy gaps with magnitudes that depend inversely on the square of the tube radius, whereas isolated armchair tubes do not have energy gaps. Additionally, armchair nanotubes packed in bundles have pseudogaps, which exhibit an inverse dependence on tube radius. These observed energy gaps suggest that most "metallic" single-walled nanotubes are not true metals, and they have implications for our understanding of the electronic properties and potential applications of carbon nanotubes.     

“渔光互补”下的微电网多目标能量优化调度策略

针对“渔光互补”下的微电网系统,为平衡能源“不可能三角”,提出一种多目标优化的能量优化调度方法。首先,基于“渔光互补”背景建立光-蓄-荷微电网系统模型,提出包含经济性、环保性及综合性的多维动态目标函数。其次,考虑麻雀搜索算法存在多样性不足和易陷入局部最优的缺陷,提出基于模拟退火算法及混合策略改进的麻雀搜索算法（SA-ISSA）的微电网能量优化调度策略。最后,针对上海崇明璞叶小镇“渔光互补”工厂化养殖基地进行实例验证,采用SA-ISSA算法对微电网模型求解,获得最优能量调度方案。实验结果表明,SA-ISSA算法在解决微电网能量优化调度问题上具有更好的性能和应用价值,可为“渔光互补”下微电网能量优化调度策略提供参考。     

The validity of the "diradical" hypothesis: direct femtoscond studies of the transition-state structures

Direct studies of diradicals, the molecular species hypothesized to be archetypal of chemical bond transformations in many classes of reactions, have been made using femtosecond laser techniques with mass spectrometry in a molecular beam. These studies are aimed at "freezing" the diradicals in time and in the course of the reaction. The passage of these species through the transition-state region was observed and the effect of total energy and alkyl substitution on the rates of bond closure and cleavage was examined. The results establish the nature of these intermediates and define their existence during reactions.     

Satellite elongation into a true "sky-hook"

The theoretical possibility of self-supporting cables extending into space from earth and from extraterrestrial rotating or revolving bodies is examined. In principle, augmentation (and duplication) of the installation and the launching of masses into orbit or into space could be accomplished with energy derived entirely from the rotation of the central body. In practice, a portion of the total energy requirement would probably be supplied by simple mechanical devices.     

高校图书馆"服务"与"爱"

从图书馆的服务工作角度阐述了服务是一种爱的栽体,应将爱融入服务工作之中;强调了全球信息化的今天,图书管理员应丰富自己的知识,提高自己的能力,将爱落实到实处。     

优质型寿光芦花肉用仔鸡营养需要的研究

该试验的能量、蛋白质分别设高、中、低三个档次,9个水平.试验结果表明:各组试验鸡的增重、饲料转化比,屠宰率以及肉质品质均达到试验设计要求.其营养需要以中能量中蛋白(能量前期2.9兆卡/公斤,后期3.0兆卡/公斤;蛋白质前期21%,后期19%)或中能量低蛋白(能量前期2.9兆卡/公斤.后期3.0兆卡/公斤;蛋白质前期19%,后期17%)的水平较为合理.     

能源植物小桐子的利用与研究进展

对小桐子作为能源植物的发展前景进行了展望,对其种质创新结果进行了初步报道.     

关于图书馆"绿色"与"生态"的几点看法

随着人类生存环境的日益恶化,人们的环保意识不断增强,对于图书馆的建设与发展人们也从多放面给予“绿色”与“生态”的关注。但对于“绿色”与“生态”内涵的理解,某些生态学概念与原理的运用还有待探讨。就这些问题提出自己的见解,并认为真正的绿色、生态图书馆不只停留在理论上,而是应从建筑、能源、环境等方面入手,在现实中建成。     

新疆“资源诅咒”效应验证分析

新疆自然资源富集但经济相对落后,与自然资源相对贫乏的我国广东省经济差距越来越大,是否呈现“资源诅咒”效应,本研究提出4个方面的依据验证新疆在优势自然资源转换中已呈现“资源诅咒”效应。验证结果显示,新疆能源、石油、天然气、煤炭资源贫困指数均大于1;新疆城镇居民人均收入匮乏;与资源相对不丰裕的广东省GDP对比,差异悬殊且有进一步扩大的趋势;新疆能源资源开采量增幅远高于新疆GDP增幅等充分表明新疆存在“资源诅咒”效应。     

南通市“十一五”能源发展规划环评研究

按照规划环评技术导则的思路和内容,对南通市“十一五”能源发展规划环评进行了研究。着重建立了环境影响评价指标体系,对能源规划内容进行了分析,并提出了规划调整建议以及预防和减轻不良环境影响的措施,通过采取一系列环境影响减缓措施,力求使各项污染指标控制在生态环境容量许可范围内。     

作物种质资源的非生态性偏差和人类行为下的种质生态伦理

作物的生产是以利用自然生态能量为前提的物质生产,任何作物种质资源都要回归自然生态系统才能进行能量截获和物质合成,因此,作物种质的“运筹”需要接受种质生态伦理的约束。种质生态伦理是指种质资源对其生存的外部生态环境所产生作用的伦理性约束,是种质资源作为非单一属性自然资源秉承自然法则的内在动力和外在要求。本文阐述了作物种质资源的非生态性偏差并对非生态性偏差进行了生态学分析,提出了“种质运筹”的概念,并论述了种质生态伦理约束的理论内核,从种质生态伦理角度诠释了种质运筹的伦理生态学内涵。     

"Frozen" transition States: pentavalent carbon et Al

Organic ligands have been designed for the stabilization of specific geometries of compounds of nonmetallic elements. These ligands have made possible the isolation, or direct observation, of large numbers of trigonal bipyramidal organo-nonmetallic species. Many of these species are analogs of transition states for nucleophilic displacement reactions and have been stabilized by the ligands to such a degree that they have become ground-state energy minima. Ideas derived from research on these species have been applied to carbon species to generate a molecule that is an analog of the transition state for the associative nucleophilic displacement reaction. The molecule is a pentavalent carbon species that has been observed by nuclear magnetic resonance spectroscopy.     

Honeybee navigation: nature and calibration of the "odometer"

There are two theories about how honeybees estimate the distance to food sources. One theory proposes that distance flown is estimated in terms of energy consumption. The other suggests that the cue is visual, and is derived from the extent to which the image of the world has moved on the eye during the trip. Here the two theories are tested by observing dances of bees that have flown through a short, narrow tunnel to collect a food reward. The results show that the honeybee's "odometer" is visually driven. They also provide a calibration of the dance and the odometer in visual terms.     

桂东南“6.23”特大暴雨天气过程分析

利用常规观测资料、卫星云图等资料,对2012年6月21～24日广西东南部特大暴雨天气过程进行个例分析。结果表明,高空槽、低涡和切变线长时间维持在广西中部是此次特大暴雨发生的主要因素。物理量诊断分析得出,充分的水汽条件和不稳定层结的能量场在强降水发生前已形成,强降水发生过程中,强辐合明显,短时强对流天气容易发生。分析红外云图和TBB均可以很好反映了此次特大暴雨天气过程出现的强降水时段。     

基于环保理念的“绿色图书馆”建设

国家＂十一五＂规划中,将建设节约环保型社会作为重点内容,实行限制与鼓励性政策并举的方式,制定建筑节能环保措施,提高建筑物能源利用效率和环保功能。图书馆作为公共文化建筑物,是现代文化的标志性建筑物,理应践行绿色环保理念,引导时代潮流。本文提出了＂绿色图书馆＂的构建理念,并从建筑理念、建筑模式以及建筑原则等多方面进行论述,以探究＂绿色图书馆＂在未来社会中的价值。     

Taking the "waste" out of "wastewater" for human water security and ecosystem sustainability

Humans create vast quantities of wastewater through inefficiencies and poor management of water systems. The wasting of water poses sustainability challenges, depletes energy reserves, and undermines human water security and ecosystem health. Here we review emerging approaches for reusing wastewater and minimizing its generation. These complementary options make the most of scarce freshwater resources, serve the varying water needs of both developed and developing countries, and confer a variety of environmental benefits. Their widespread adoption will require changing how freshwater is sourced, used, managed, and priced.     

"Imprinting" in nature

Much laboratory research is based on the assumption that the learning of parental characteristics by young nidifugous birds is rooted on visual factors. Naturalistic observations of ground- and hole-nesting duck species, augmented by sound amplification equipment, indicate that hatchlings are exposed to the call of their mother for a relatively long period before they are exposed to the sight of her.     

中国“三废”产生排放量的年际变化研究

该文选取1995-2013年中国废水、废气、废弃物的产生排放量作为研究对象,分析了近10a来全国"三废"排放状况。结果表明:全国废水排放从1995年的373亿t上升到2013年的695亿t,上升了近1倍,形势严峻;SO2排放一直处于一种比较顽固稳定的状态;烟(粉)尘排放总量与固体废弃物排放总量均呈降低趋势,但工业SO2、烟(粉)尘排放量却在波动上升,工业固体废弃物年产生量仍达年3亿t之多。进一步开展节能减排、提高循环利用率、提高个人环保意识是必然要求。     

“3S”技术与精细农业

本介绍了“3S”技术的概念及其一般应用,阐明了“3S”技术与精细农业的关系,提出我国应加强“3S”技术和精细农业研究与实践。     

"Where" and "what" in vision

The mixture of a few horizontal and vertical line segments embedded in an aggregate of diagonal line segments can be rapidly counted and their positions rapidly determined by a parallel (preattentive) process. However, the discrimination between horizontal and vertical orientation (that is, discrimination of a single conspicuous feature) requires serial search by focal attention. Under recent theories of attention, focal attention has been assumed to be required for the recognition of different combinations of features. According to the findings of this experiment, knowing "what" even a single feature is requires time-consuming search by focal attention. Only knowing "where" a target it is mediated by a parallel process.