Detection of molecular alignment in confined films

Optical second harmonic generation was used to study the in-plane alignment of self-assembled silane monolayers attached to a glass surface under mechanical loading. The measurements allow correlation of the macroscopic forces acting on the monolayer with the average orientation and the azimuthal molecular alignment of the terminal molecular entity. Compression and shear forces lead to an alignment of the initially randomly oriented molecules on a macroscopic length scale. The change in azimuthal alignment of molecules under mechanical stress was found to be irreversible on the time scale of 12 hours, whereas changes of the molecular tilt angle were reversible.     

Turning down the heat on thin films

Superconducting thin films will be essential to any practical application of superconductivity to microelectronics. Scientists have now succeeded in putting these thin films onto silicon, which is the base element in most integrated circuits.     

Surface order and stability of langmuir-blodgett films

Angstrom-resolution atomic force microscope images of Langmuir-Blodgett monolayers and multilayers of cadmium arachidate in air and under water show a dramatic change from a disordered arrangement to a crystalline lattice by the addition or removal of a single layer of molecules. The disordered surface is less stable than the ordered one to mechanical stresses such as atomic force microscopy tip forces or at the air-water contact line during contact angle measurements. The difference in the degree of order in the alkyl chains is attributed to the strong attractive interaction between headgroups in the presence of the divalent cation.     

Fluid drop-like transition of erythrocytes under shear

Red cells dispersed in a continuous medium of high viscosity possess the flow properties of fluid drops. The cells at rest are biconcave, while under shear they become progressively deformed into prolate ellipsoids, their long axis aligned parallel to the flow direction. The red cell membrane rotates around the hemoglobin like a tread of a tank. At high rates of shear this mechanism greatly reduces viscosity at all hematocrit values.     

月季花色素的稳定性研究

对月季花色素稳定性的研究结果表明:常见金属离子中的Mg2+、Al3+、Ca2+、Cu2+、Zn2+对月季花色素的稳定性影响不大,Fe3+有一定的影响;食品添加剂对色素稳定性影响不大;月季花色素的抗氧化能力弱;光线对色素的稳定性有很大的影响,其吸光度值随着光线照射时间的延长而降低.     

The importance of threading dislocations on the motion of domain boundaries in thin films

Thin films often present domain structures whose detailed evolution is a subject of debate. We analyze the evolution of copper films, which contain both rotational and stacking domains, on ruthenium. Real-time observation by low-energy electron microscopy shows that the stacking domains evolve in a seemingly complex way. Not only do the stacking boundaries move in preferred directions, but their motion is extremely uneven and they become stuck when they reach rotational boundaries. We show that this behavior occurs because the stacking-boundary motion is impeded by threading dislocations. This study underscores how the coarse-scale evolution of thin films can be controlled by defects.     

退火对掺铟氧化锌薄膜结构及光学性能的影响

采用溶胶-凝胶法在石英衬底上制备掺铟氧化锌薄膜,研究不同退火温度对薄膜结构及发光性能的影响.结果表明,掺铟氧化锌薄膜仍为六角纤锌矿结构的ZnO相,在大于450 nm的波段薄膜样品的透射率都较高;随着退火温度的升高,透射率先增后减,600℃时达到最大;薄膜样品的光学带隙都小于纯ZnO的理论值(3.37 eV),且随退火温度的升高呈先减后增趋势;样品的结晶度与发光强度随着退火温度的升高而增强.     

Growth of thin chemically bonded diamondlike films by ion beam deposition

Carbon films with a diamondlike structure that are chemically bonded to surfaces have been deposited by means of low-energy C(+) ion beams. When mass-selected C(+) beams at energies in the range from 20 to 200 electron volts impinge on atomically clean surfaces, the first carbon monolayer grows as a carbide structure that is chemically bonded to the surface. As deposition continues, the structure evolves over the next several atomic layers into a diamondlike structure. These pure carbon films are strongly adhered to the surface through the carbide bonds, which also provide for an intimate interface. There are significant applications for such films, particularly as insulators and doped semiconductors.     

Ferroelectricity at the nanoscale: local polarization in oxide thin films and heterostructures

Ferroelectric oxide materials have offered a tantalizing potential for applications since the discovery of ferroelectric perovskites more than 50 years ago. Their switchable electric polarization is ideal for use in devices for memory storage and integrated microelectronics, but progress has long been hampered by difficulties in materials processing. Recent breakthroughs in the synthesis of complex oxides have brought the field to an entirely new level, in which complex artificial oxide structures can be realized with an atomic-level precision comparable to that well known for semiconductor heterostructures. Not only can the necessary high-quality ferroelectric films now be grown for new device capabilities, but ferroelectrics can be combined with other functional oxides, such as high-temperature superconductors and magnetic oxides, to create multifunctional materials and devices. Moreover, the shrinking of the relevant lengths to the nanoscale produces new physical phenomena. Real-space characterization and manipulation of the structure and properties at atomic scales involves new kinds of local probes and a key role for first-principles theory.     

新形势下做好高校维稳工作探析

本文针对新形势下影响高校安全稳定因素呈现多样化、复杂化、深层次的趋势,以课题组的调查总结为基础,深入分析了目前影响高校安全稳定的主要原因,提出加强大学生思想政治教育,帮助学生树立正确的理想信念;加强校园舆情监控和舆论引导;加强校园制度建设,创造和谐稳定的育人环境;加强高校维稳机制建设,构建科学稳控体系;加强与地方政府合作,消除校内外周边隐患等五个方面工作建议,以更好地维护高校的安全稳定。     

电子探针能谱测定膜厚的E_f理论

研究利用电子探针能谱（ＥＤＳ）检测薄膜厚度的技术。该技术的核心是：①确定特征ｘ射线的临界激发能Ｅｆ;②确定所采用的半经验公式。Ｅｆ方法是一种很好的估测膜厚的近似方法,具有很好的实用价值。文中还探讨了二种确定薄膜Ｅｆ的方法。     

蔗糖业应在稳定中发展

近年来,国际上食糖产大于销,库存量逐年增加,糖价呈现逐级走低的态势.从国际比较看,我国食糖生产成本高于泰国、巴西、澳大利亚等国家,价格上缺乏竞争力.据此,相当部分人士得出了蔗糖业应减少面积、压缩规模的结论.那么,蔗糖业应该慢慢萎缩,让出市场,还是在稳定中加以发展?我们分析如后供参考.     

客观面对直播稻的迅速发展 研究掌握直播稻的稳产技术

在对我国水稻种植方式演变历史回顾的基础上,就当前江苏省直播稻不推自广的主要原因进行分析和对策探讨。我国水稻育苗移栽始见于东汉,普及于唐宋以后;育苗移栽取代水稻直播,不仅有效地控制了杂草为害,而且增加了复种,缓解了稻麦两熟季节紧的矛盾,并一直成为主流的植稻方式;但是直播稻并没有完全消失,尤其是在人少地多或劳力缺乏的情况下,直播仍是首选方式。近年来江苏省直播稻迅速扩大,这与农村劳动力不足、水稻条纹叶枯病流行以及种稻效益低下有着密切的联系;当然也有除草剂应用突破和直播稻栽培技术的进步等促进作用。麦后直播水稻（简化了育秧程序,播种期推迟）安全生长期缩短,因此对江苏省里下河麦稻两熟热量资源偏紧地区则必须对水稻品种类型的调整和适宜直播稻品种的选用以及最迟播期等都须进行深入研究和严格界定;对淮北地区一定要引导农民服从自然规律并迅速从盲目扩种直播稻的误区中走出来,若该类地区劳力资源不足且机插条件又不许可,则可适度推行抛秧稻栽培技术。     

Control of structure and growth of polymorphic crystalline thin films of amphiphilic molecules on liquid surfaces

The spontaneous formation and coexistence of crystalline polymorphic trilayer domains in amphiphilic films at air-liquid interfaces is demonstrated by grazing incidence synchrotron x-ray diffraction. These polymorphic crystallites may serve as models for the early stages of crystal nucleation and growth, helping to elucidate the manner in which additives influence the progress of crystal nucleation, growth, and polymorphism and suggesting ways of selectively generating and controlling multilayers on liquid surfaces. Auxiliary molecules have been designed to selectively inhibit development of the polymorphs, leading primarily to a single phase monolayer.     

建构观下教师角色的定位

在建构主义理论的指导下,教师必须改变机械的和静态的数学教学观,向动态的、易谬(经验主义和似经验主义)的数学观念转化。要重新认识教师在教学过程中的主导作用,教师不再是简单的知识传授者,而应是数学建构活动的激励者、组织者、参与者和导向者。     

Machining oxide thin films with an atomic force microscope: pattern and object formation on the nanometer scale

An atomic force microscope (AFM) has been used to machine complex patterns and to form free structural objects in thin layers of MoO(3) grown on the surface of MoS(2). The AFM tip can pattern lines with 相似文献   

车-液耦合响应下液罐车稳定性控制仿真

为了提高液罐车行驶安全性、减少液罐车侧翻、失稳所带来的危害,对于液罐车在转向或换道时车-液耦合动态响应对整车稳定性的影响进行了研究。联合液体纳维斯托克斯和流动控制方程,应用计算流体动力学软件ANSYS/Fluent建立并求解液体晃动模型,通过结合液体晃动模型和三自由度液罐车刚体模型获得液罐车车-液耦合动力学模型,分析有无控制策略情况下,液体晃动对液罐车横向稳定性的影响。仿真结果表明:提出的模糊差动制动控制策略能够有效提高车辆抗侧翻能力,减少罐车运输过程中交通事故的发生,对液罐车运输有指导意义。     

生态环境下翻译教学模式探讨

随着经济全球化的发展,社会对翻译人才提出了更高的要求,然而在高校中翻译教学模式和其他课程的教学模式相比,还相对滞后.本文分析了翻译课堂中存在的问题,在“以学习者为中心”的翻译教学理论指导下,提倡“以学生为中心”的教学模式,鼓励使用同伴互评式教学和翻译评注式教学.     

新形式下工会如何依法履行自己的职责

通过对新颁布的《工会法》的学习研究,进一步探讨了在新形式下,工会如何依法履行自己的职责,发挥“桥梁”和“纽带”的作用。