反应面分析在田间试验中的应用

以14个小麦和9个油菜新品系为材料,通过常规方差分析和反应面分析2种方法的比较,探讨了反应面分析法在农业田间试验中应用的优势。     

Low-energy atom scattering from surfaces

Experiments in which low-energy atoms are scattered from surfaces represent an important new method for structural analysis of the topmost atomic layers of a surface. The method and its application in a number of areas in surface science, such as detecting surface defects and studying lattice dynamics, are discussed.     

Nitriding iron at lower temperatures

The microstructure in the surface layer of a pure iron plate was refined at the nanometer scale by means of a surface mechanical attrition treatment that generates repetitive severe plastic deformation of the surface layer. The subsequent nitriding kinetics of the treated iron with the nanostructured surface layer were greatly enhanced, so that the nitriding temperature could be as low as 300 degrees C, which is much lower than conventional nitriding temperatures (above 500 degrees C). This enhanced processing method demonstrates the technological significance of nanomaterials in improving traditional processing techniques and provides a new approach for selective surface reactions in solids.     

Mimicking surface plasmons with structured surfaces

Metals such as silver support surface plasmons: electromagnetic surface excitations localized near the surface that originate from the free electrons of the metal. Surface modes are also observed on highly conducting surfaces perforated by holes. We establish a close connection between the two, showing that electromagnetic waves in both materials are governed by an effective permittivity of the same plasma form. The size and spacing of holes can readily be controlled on all relevant length scales, which allows the creation of designer surface plasmons with almost arbitrary dispersion in frequency and in space, opening new vistas in surface plasmon optics.     

一类加权有理插值样条曲面及局部约束控制

目的 构造一类新的基于函数值与偏导数值的加权有理插值样条曲面,讨论该样条曲面的相关性质并分析曲面的局部约束控制。方法 一方面,先从x方向构造有理三次插值样条,再从y方向构造二元有理插值样条曲面;另一方面,按相反次序构造另一个二元有理插值样条曲面;最后将两种插值曲面加权得到一类新的有理插值样条曲面。结果 讨论插值曲面的性质,包括基函数、边界性质、积分加权系数的性质以及误差估计。通过选择合适的参数和加权系数,在不改变插值数据的前提下实现对插值区域内的局部约束控制。结论 实验结果表明,新的加权有理插值样条曲面具有良好的约束控制性质。     

借助纳米珠制作单分子DNA芯片

传统的单分子DNA芯片制作技术主要依靠稀溶液铺设,有很大的随机性,即有许多DNA分子重叠而无法观察,还有一部分基片上没有样品,造成浪费,为克服上述缺点,作者采用了一种新的单分子芯片铺设技术,纳米珠作为单分子DNA的连接载体,利用其空间位阻作用将DNA分子沉降到经过表面化学处理的基片表面,纳米珠的直径和DNA长度控制芯片上样点间距,去除纳米珠后,获得单分子DNA纳米阵列芯片。为单分子、高通量DNA芯片的制作做了新的探索。这个技术的完善将为今后单分子DNA研究开辟新的途径。     

扇贝捕捞网具的改良设计

对虾夷扇贝捕捞网具进行了改良设计,即以“雪爬犁”架将传统贴地的拖网托离海底表面,以竖直交错排列的非金属惊扰棒取代传统的3道横排粗铁链,以专用的排石口排掉进入网内的石块,以拾贝板分拣、过滤并清洗扇贝。生产实践证明：采用改良设计的新型网具作业,具有降低扇贝破损率、提高采捕率、减轻拖网作业对海底生态环境的破坏程度、减少拖网耗能、捕捞的扇贝清洁无泥沙等优点。     

中国再制造工程及其进展*

再制造工程是废旧机电产品高技术修复改造的产业化,是循环经济和节能环保产业的重要技术支撑。中国的再制造工程经历了产业萌生、科学论证和政府推进三个阶段。中国特色的再制造主要基于尺寸恢复和性能提升,并以先进的寿命评估技术、纳米表面工程和自动化表面工程技术为支撑,其重要特征是再制造产品的质量和性能不低于原型新品,成本为新品的50 %,节能60 %,节材70 %,显著改善环保。具有中国特色的再制造模式已逐渐形成,并取得了重要成果。     

New mechanism of nonequilibrium polymer adsorption

Nonequilibrium states of surface composition can be extremely long-lived when polymer chains adsorb competitively. In a model system (polymethylmethacrylate adsorbed from CCl(4) onto oxidized silicon previously saturated with polystyrene), it is shown that a weakly adsorbing polymer was sterically pinned to a surface by a more strongly adsorbing polymer. The dynamical evolution of the surface composition was strongly nonexponential in time and non-Arrhenius in temperature; the phenomenology is analogous to bulk glasses. This interpretation offers a new mechanism to explain why weakly adsorbing chains may bind to surfaces, as well as a direction in which to look for a method to release them.     

Irradiance modulation used to examine sound-radiating cuticular motion in insects

A new, noncontact, optical technique for measurement of movements smaller than a few micrometers has been used to record cuticular motion of insects as they produce sound. The instrument described is highly sensitive to surface movement and offers good spatial resolution, broad dynamic range, tolerance of substantial background motion of the target surface, portability, and simplicity, and as such appears to hold promise for measuring other biologically interesting motions that have proved difficult to measure by other available techniques.     

耐磨复合合金粉末氧乙炔焰喷焊提高零部件使用寿命的研究

本工艺是应用氧乙炔火焰为热源,喷焊耐磨复合合金粉末。使机器零件表面层获得耐磨、耐腐蚀、抗高温氧化等功能,从而提高零件和机械的服役寿命。本文简述耐磨复合合金粉末研制特点、涂层性能的试验研究、模拟及田间试验结果、喷焊工艺要领和提高喷焊层耐磨粒磨损机理的初步剖析。复合合金粉末Pygt-801是我们研制成功的新粉末。它具有廉价和优异的性能。与类似商品比较,可获得显著的经济效果。经较长时间的喷焊实践和工艺的不断改进,已获得硬度高、耐磨和良好冲击韧性的喷焊层。喷焊层硬质相的显微硬度HV=1450～1800(相当HRC76—81),粘结相(机体)HV=805～965(HRC 63.2～68)。经过模拟试验与田间试验,其耐磨性是65Mn钢的二倍。     

木质碳纤维材料的活化与功能化

为探讨用木质生物质替代石油等化石资源，制备新型功能化活性碳纤维材料，系统归纳了木质碳纤维在以下几方面的研究现状与发展趋势:1）以木质生物质为原料，通过固化、炭化，物理、化学活化处理，制备活性木材液化物碳纤维；2）通过孔隙调整、表面改性和离子化处理，对活性木材液化物碳纤维进行功能化处理；3）活性、功能化处理对木质碳纤维的晶体结构、表面含氧基团结构、孔隙结构和表面形态结构、物理性能和吸附性能、环保和抗菌功能的影响。并在此基础上，提出了今后一段时期内木质碳纤维的活化、功能化研究存在的科学问题与思考。      

激光切削陶瓷的试验研究

A new process of laser machining ceramic material is experimentally studied. The microstructure of the cut surface is as the same as the substrate when using acousticoptical Q-switch YAG laser to remove the stock by vaporization. The cutting accuracy of t     

掺N、S综纤维素基水热炭的制备及其表征

为了得到一种具有较高比表面积且掺杂N、S元素的新型碳材料,且为这种碳材料的应用提供一定的数据支持,以杨木木粉制得的综纤维素为原料,以氨水和正硅酸乙酯反应制得的纳米SiO_2为模板剂,L-半胱氨酸作为N、S元素的来源,采用水热炭化法在一定温度下制得了水热炭材料,并在氮气气氛下对其进行烧结处理。通过SEM、能谱分析、XPS、TG-DTG等测试方法对其进行表征,结果表明,本实验制得最终产物含有N、S元素,其质量分数分别为17.07%和1.81%,比表面积为220 m~2/g,较参照样具有显著提高,并显示出良好的热稳定性。     

南京地区1次大雾过程中的多普勒雷达回波研究

为探讨大雾这种灾害性天气下,新一代多普勒雷达上显示的回波特征以及这种回波的形成机制,以南京地区2007年12月20日1次大雾过程中的多普勒雷达回波为例,利用实际的气象观测资料,对比了折射指数、地面温度、露点温度、水汽压、气压差与回波强度之间的相关性,并探讨了湍流混合作用对回波的影响。结果表明:大雾发生过程中的湍流混合作用引起折射指数的不均匀结构,加之高湿的环境,对多普勒雷达回波有直接影响;通过研究大雾天气下的超折射现象,确定了雾与超折射层之间的关系,对揭示雾与超折射的关系有积极意义。     

Planetary science. The glitter of distant seas

It has long been known that Saturn's largest moon, Titan, has a thick nitrogen atmosphere, which obscures the underlying surface. In his Perspective, Lorenz highlights the report by Campbell et al., who have used the giant Arecibo and Green Bank radio telescopes as a radar to probe Titan's hidden surface. The surface appears to be distinct from those of the icy satellites of Jupiter, in both brightness and polarization. The new data show sharp spikes in the reflected microwave spectrum, indicating large, smooth areas of radar-dark material. These features suggest the widespread existence of lakes or seas of liquid hydrocarbons on Titan.     

三倍体毛白杨木质(刨花)复合材料的研制

以北京林业大学培育的人工林三倍体毛白杨为原料 ,研制以大片刨花为表层、细碎刨花为芯层的新型三层结构的木质 (刨花 )复合材料 .分析了表芯层刨花比、表芯层施胶量比、热压温度、热压时间对复合材料物理力学性能的影响 ,并且确定了生产这种复合材料的最佳工艺 .用该工艺生产的木质 (刨花 )复合材料 ,其物理力学性能达到或超过国家GB T4 897 92标准 .     

New approaches to surface structure determinations

Progress in understanding the many scientifically interesting and technologically important processes that occur at surfaces has been slowed by the absence of basic structural information. A variety of new techniques are being developed to attack this central problem in surface science. With the new surface probes it is now possible to quantitatively determine the arrangement of atoms in the first monolayers of a solid. This provides the basis for exciting advances in surface science.     

甜瓜果实体积与表面积的估算方法

以黄河蜜甜瓜为试材,以排水法测定的体积和纸重法测算的表面积为依据,对椭球体体积与表面积计算公式进行了修正,建立了用纵、横半径估算厚皮甜瓜果实体积与表面积的新方法。检验结果表明,用2个修正计算公式估算的甜瓜体积和表面积值与实测结果之间无显著差异。修正公式可用以快速而准确地估算厚皮甜瓜果实的体积与表面积。