薄膜材料形貌的计算机图像分形研究

薄膜材料的表面形貌直接影响到它的电阻率、介电常数等物理性能,描述薄膜材料的表面形貌对了解其可能产生的物理性能具有重要意义。由于分形盒维数能够综合反映出晶体大小,晶体的不规则程度、晶体排列的致密性等表面形貌结构特征,因而本文的研究拟运用计算机图像分析技术,从分形的角度综合描述薄膜材料表面形貌,并将其分形维数的大小和其电阻率的大小关联起来。本文的研究将有助于阐明晶体排列等结构与物理性能的关系,有助于指导材料制备。

LNIP改进算法及其在材料形貌分类中的应用研究

针对LNIP(local neighborhood intensity pattern)纹理特征提取算法在旋转、尺度变化方面存在的不足,提出了一种LNIP改进算法RSILNIP(rotation and scale invariant LNIP)。首先,同化邻域信息之间的特征以提高其旋转不变性;其次,采用统一编码的方式降低特征提取维度;然后,提取多尺度特征并进行选择,从而增强其尺度不变性;最后,采用并联方式合并特征。将改进算法与同类算法在公共数据集Outex和材料扫描电镜图像数据集SEMdataset上进行分类精度测试,得到改进算法的分类精度分别达到96.76%和98.26%,说明改进算法在图像分类和材料形貌归类上有较好的工程应用价值。

神经细胞生长行为的仿生学思考—材料的形貌学作用

体外培养鼠胚脊髓细胞时神经纤维的生长行为受到基质高分子材料的形貌学影响。蚯蚓的匍匐运动也同样受到地面形貌的作用。种属和结构层次不同的两类生物体在其运动行为的地貌学依赖规律却非常相似。

基于电涡流传感器的金属材料表面形貌三维可视化检测

针对金属材料表面形貌检测问题,论文设计制作了一种高空间分辨力的电涡流传感器,可实现金属管道内壁复杂表面形貌及裂纹的高分辨检测。论文采用ANSYS有限元分析软件对传感器进行了仿真分析,验证了传感器对金属材料表面形貌变化的高空间分辨检测能力。论文同时对该种传感器性能进行了实验测试。实验结果表明,相比传统的电涡流传感器,本文设计的传感器对裂纹、对金属材料表面形貌变化具有更高的检测分辨力。最后,论文采用三维可视化技术,将传感器对金属板表面形貌的扫描检测数据转化成三维图像,可直观地显示出被测金属板表面形貌变化及裂纹位置。

不同形貌纳米SnO_2的可控合成及催化发光传感器

以碳纳米管(Carbon nanotubes,CNT)为模板,采用液相沉积法,通过改变煅烧温度可控合成了SnO2-CNT复合纳米材料、SnO2纳米棒和SnO2纳米粒子3种形貌的SnO2纳米材料,研究了3种形貌的SnO2纳米材料对乙酸乙酯催化发光的影响.考察了3种不同形貌SnO2纳米材料的纳米尺度和结构,讨论了影响纳米材料催化发光特性的因素,研究了3种不同形貌SnO2纳米材料对乙酸乙酯催化发光图谱和强度的变化,建立了3种新型、高效的不同形貌纳米催化发光传感器.

基于天然纳米管功能修饰的新材料制备

埃洛石Al2Si2O5(OH)4.nH2O是一种天然的纳米管材料,基于其中空结构、高长径比、低羟基密度等特性,通过物理、化学手段进行修饰可以获得性能优异的新型功能材料,已成为材料、化学、物理、电子等多学科交叉研究的前沿领域。在介绍埃洛石纳米管结构特性的基础上,系统总结了天然纳米管通过功能修饰制备新材料的国内外最新研究进展,包括生态环境材料、催化材料、仿生材料、有机/无机杂化材料、生物医药材料和储能材料。阐述了其制备技术、表征手段、结构形貌和功能特性等,展示了这些新型功能材料的广阔应用前景。

静电纺纳米纤维表面形貌的制备及其生物医学应用

通过模仿天然细胞外基质的成分和结构特性对材料表面形貌进行设计与调控,可获得新型仿生材料,并广泛应用于生物医学领域。其中,静电纺纳米纤维通过调控孔隙率、比表面积及微纳米结构等,可以模拟天然细胞外基质的结构,实现其生物功能。本文将提供不同表面形貌电纺纤维的概述。首先介绍静电纺丝的原理、设备和参数,然后讨论电纺纤维的4种表面形貌:纳米孔、串晶、沟槽和皱缩结构的制备原理、方法及在生物医学领域的应用,并对该领域相关研究和研究现状进行评价。

Low-Temperature Growth and Photoluminescence of SnO_2 Nanowires

SnO2 nanowires with a diameter of 25nm are synthesized at 550~C by Au-Ag catalyst assisted thermal evapora- tion of SnO powders. The room-temperature photoluminescence spectra （PL） of the prepared nanowires are measured. Among the four PL peaks,the peak of 418nm is newly observed. This peak is caused by the plane defects of the twinned crystal nanowires. The formation of SnO2 nanowires at low temperature is pursued on the basis of the VLS mechanism and application of the reaction source of SnO. We suggest that the chemical reactions of the low temperature and low concen- tration of the vaporized species are responsible for the thinner size of the SnO2 nanowires.

同轴静电纺丝法制备神经生长因子纳米纤维缓释载体

背景:传统的缓释药物的制备过程,常需要把蛋白质类药物与有机溶剂混合,降低了蛋白质的活性,同轴静电纺丝法减少了蛋白质与有机溶剂的接触,有望提高蛋白质的活性,提供新型的缓释载体。目的:探讨应用同轴静电纺丝技术制备蛋白质类药物神经生长因子"壳-芯"结构纳米纤维缓释载体的可行性。设计、时间及地点:对比细胞学实验,于2007-07/12在东华大学生物科学与技术研究所完成。材料:乳酸己内酯共聚物(50∶50,Mw=378,839g/mol,Mw/Mn=2.7324)由东华大学生物科学与技术研究所提供;β-神经生长因子为R&D Systems公司产品;牛血清白蛋白为Sigma-Aldrich公司产品;大鼠肾上腺嗜铬细胞瘤细胞PC12细胞由中国科学院细胞库提供。方法:应用同轴静电纺丝技术制备以乳酸己内酯共聚物为壳,神经生长因子和牛血清蛋白为芯的复合纳米纤维;然后进行体外缓释8周,将不同时间点缓释液加入到无血清RPMI培养基中,培养大鼠肾上腺嗜铬细胞瘤细胞(PC12细胞)。根据芯层溶液流速的不同分为0.10,0.15,0.25mL/h3组纳米纤维。主要观察指标:通过扫描电镜和透射电镜对纳米纤维形貌特征进行表征,应用图像分析软件Image-J计算纳米纤维的直径分布范围;PC12细胞在神经生长因子的诱导下可以向神经元细胞分化,通过观测其分化率检测神经生长因子的生物活性。结果:成功制备了具有壳芯结构的乳酸己内酯共聚物/牛血清蛋白/神经生长因子纳米纤维,纳米纤维的平均直径和直径分布范围随着芯层溶液流速的增加而增大。当芯层溶液流速为0.10mL/h时或0.15mL/h,纺丝稳定,所得纤维平均直径较小,直径分布范围较窄,当芯层溶液流速为0.25mL/h,纺丝不稳定,有大量"串珠"出现。在各个时间点乳酸己内酯共聚物/牛血清蛋白/神经生长因子缓释上清液能够诱导PC12细胞分化神经元细胞,生长轴突,说明神经生长因子保持了一定程度的生物活性至少8周。结论:应用同轴静电纺丝技术可制备蛋白质类药物神经生长因子"壳-芯"结构纳米纤维缓释载体。

复杂多层级银颗粒的合成新方法

将银胺络合溶液与琼脂溶胶混合均匀,取少量混合液用乙醇稀释后滴在铝箔表面,于室温下逐渐干燥,在铝箔表面合成出毛线球形的复杂多层级银颗粒;通过调节琼脂、琼脂糖及聚乙烯醇-124三种溶胶的黏度,合成出不同形貌的复杂多层级银颗粒。实验结果表明,在黏度较低(0.001~0.01 Pa·s)条件下可以得到花状银颗粒,在黏度中等(0.01~1 Pa·s)条件下得到毛线球形银颗粒,在黏度较高(大于1 Pa·s)条件下得到片状交叉银颗粒。通过调节溶胶的黏度,可以调控和改变液滴内反应物的反应-扩散及聚集过程,从而得到形貌复杂多样的介尺度晶体结构。

Evolution of Self-Organized Ge Quantum Dots During Ultra High Vacuum Annealing

The evolution of self organized Ge quantum dots structure is investigated by scanning tunneling microscopy and atomic force microscopy during annealing treatment up to 700℃ in an ultra high vacuum(UHV) system.When the sample temperature rises to 630℃,a great amount of new dots emerge on the wetting layer,which are believed to be incoherent islands compared with the dislocation free coherent islands formed during molecular beam epitaxy growth.

Selective synthesis and shape-dependent photoluminescence properties of (Y_(0.95)Eu_(0.05))_2O_3 submicron spheres and microplates

Red-emission （Y0.95Eu0.05）2O3 submicron spheres and microplates were selectively obtained via hydrothermal precursor synthesis （150 °C, 12 h） followed by calcination at 1000 °C. Characterizations of the products were carried out by combined means of XRD, FT-IR, FE-SEM and PL analysis. The precursors could be modulated from basic-carbonate submicron spheres to normal carbonate microplates by increasing the molar ratio of urea to Y＋Eu from 10 to 40-100. The resultant oxides largely retain their respective precursor morphologies at 1000 °C, but morphology confined crystal growth was observed for the microplates, yielding more enhanced exposure of the （400） facets. Both the （Y0.95Eu0.05）2O3 spheres and microplates exhibit nearly identical positions of the PL bands and similar asymmetry factors of luminescence [I（5D0→7F2）/I（5D0→7F1）, ～11] under 250 nm excitation, but the microplates show a significantly strong red emission at ～613 nm （ ～1.33 times that of the spheres） owing to their larger particle size and denser packing of primary phosphor crystallites.

叠层方式形成彩色滤光片隔垫物的研究

本文研究了液晶显示面板彩色滤光片工艺中以叠层方式形成隔垫物的关键技术问题,即叠层隔垫物高度控制、主-附隔垫物段差的形成和主-附隔垫物段差受后续平坦层工艺的影响变化等,并提出了解决方案。在黑矩阵、红色、绿色、蓝色滤光层形成一定的叠层高度后,采用形貌追随型平坦化材料对像素区平坦,通过控制像素开口部分OC的厚度,可以实现叠层隔垫物高度的控制。采用改变叠层图案设计的方法形成主-副隔垫物高度差(Main-sub段差),段差达成范围是0.4~1.2μm,达到了灰阶曝光方式可以达到段差的水平,但成本却大幅降低。并且验证了采用形貌追随型OC材料覆盖可以较好的保持OC工艺前形成的Main-sub段差。基于以上技术制备了4 Mask彩色滤光片原型机。

Tribological behaviors of Ag-graphite composites reinforced with spherical graphite

Two kinds of Ag-graphite composites reinforced with spherical graphite(SG)and conventional flake graphite(FG)were prepared by powder metallurgy technology.The effect of graphite morphology on the tribological behavior for the Ag-SG and Ag-FG under the dry sliding wear was investigated with a pin-on-disk tribometer at a load of 3.0 N in atmosphere condition.The results indicated that the minimum wear rate of 3.5×10^-5 mm^3/(N·m)for Ag-FG was achieved and it reduced by nearly an order of magnitude,reaching 1.6×10^-6 mm^3/(N·m)for the Ag-SG.The obviously different tribological behaviors between the Ag-SG and Ag-FG were closely related to the formation of cracks in the sub-surface.The stress concentration tended to generate at the edges of flake graphite during sliding process,which resulted in the cracks and severe delamination wear of Ag-FG.However,no cracks were found around the spherical graphite in Ag-SG.The spherical graphite can effectively inhibit the initiation and propagation of cracks,achieving high wear resistance.

Examination and Research of the Surface Topography of Ultrasonic Vibration Honing Nd-Fe-B

The mechanism of ultrasonic vibration honing Nd-Fe-B has been briefly elaborated after the introduction of the strategic significance of processing Nd-Fe-B. Based on the formation principle of Scanning Electrtmic Microscope （SEM）, and at the examination with the aid of SEM to the ultrasonic vibration honing Nd-Fe-B material＇s superficial microscopic topography, the paper discusses the new processing nechanism according to the SEM examination picture. The research indicates that as a result of supersonic high frequency vibration, the path of the abrasion extends at the same time, and the supersonic cavitation effect forms the intense shock-wave, knpacting Nd-Fe-B material＇s intemal surface, providing the supersonic energy for the superticial abrasive dust＇s dimination, which directly explain that the honing processing efficiency is enhanced, and the processing surface roughness is high.

Wire electric discharge machining characteristics of titanium nickel shape memory alloy

Ti Ni shape memory alloys（SMAs） have been normally used as the competent elements in large part of the industries due to outstanding properties, such as super elasticity and shape memory effects. However, traditional machining of SMAs is quite complex due to these properties. Hence, the wire electric discharge machining（WEDM） characteristics of Ti Ni SMA was studied. The experiments were planned as per L27 orthogonal array to minimize the experiments, each experiment was performed under different conditions of pulse duration, pulse off time, servo voltage, flushing pressure and wire speed. A multi-response optimization method using Taguchi design with utility concept has been proposed for simultaneous optimization. The analysis of means（ANOM） and analysis of variance（ANOVA） on signal to noise（S/N） ratio were performed for determining the optimal parameter levels. Taguchi analysis reveals that a combination of 1 μs pulse duration, 3.8 μs pulse off time, 40 V servo voltage, 1.8×105 Pa flushing pressure and 8 m/min wire speed is beneficial for simultaneously maximizing the material removal rate（MRR） and minimizing the surface roughness. The optimization results of WEDM of Ti Ni SMA also indicate that pulse duration significantly affects the material removal rate and surface roughness. The discharged craters, micro cracks and recast layer were observed on the machined surface at large pulse duration.

A 3D evaluation method of cutting surface topography of carbon/carbon(C/C) composite

This paper aims to establish a 3D evaluation method for cutting surface topography of C/C composites. The cutting surface is measured by Talyscan 150, using 3D non-contact measurement. By evaluating 2D and 3D roughness of C/C composite and Duralumin, the 2D evaluation method of the cutting surface topography of C/C composite loses a lot of information, and the characteristics of the surface topography of C/C composite can be comprehensively and authentically evaluated only by the 3D evaluation method. Furthermore, 3D amplitude and spatial parameters are adopted to evaluate the surface and the results show that： the topography of the C/C composite is anisotropy and there are no obvious feeding textures but abrupt peaks and valleys on surface of the C/C composite, which indicates that the machining mecha- nism is different from that of the metal. In conclusion, The C/C composite surface is evaluated using a 3D evaluation method, the roughness error is small, and the unique topography characteristics earl be au- thentically evaluated.

Morphology inheritance synthesis of carbon-coated Li3VO4 rods as anode for lithium-ion battery

Li3VO4 shows great potential as an intercalation/de-intercalation type anode material for energy-storage devices. Morphology tailoring and surface modification are effective to enhance its lithium storage performance. In this work, we fabricate carbon coated Li3VO4(C@LVO) rods by a facile morphology inheritance route. The as-prepared C@LVO rods are 400–800 nm in length and 200–400 nm in diameter,and orthorhombic phase with V5+. The unique core-shell rods structure greatly improves the transport ability of electrons and Li+. Such C@LVO submicron-rods as anode materials exhibit excellent rate capability(a reversible capability of 460,438, 416, 359 and 310 m A h g^-1 at 0.2, 1, 2, 5 and 10 C, respectively) and a high stable capacity of 440 and 313 m A h g^-1 up to 300 cycles at 0.2 and 5 C, respectively.

Morphology control and shape evolution in 3D hierarchical superstructures

Hierarchical structures, in which structure is generated and controlled simultaneously at different size scales, have attracted increasing attention due to their potentials in both theoretical research and practical applications. In this review, a "non-classical crystallization" mechanism is discussed for their possibilities in morphology control of hierarchically-structured materials. Differently, this crystallization route is not based on the attaching and detaching of monomers as happened in the classical case, but through the self-organization of preformed building blocks as nanosized subunits, whose oriented attachment leads to mesocrystals with favorable morphology and texture. Representative materials including both inorganic and organic crystals are reported with possible mechanisms proposed. Synthetic protocols based on this mechanism provide unique inspirations for materials design and could be applied to morphological and structural control of new materials with optimized functions.

Advanced carbon materials for flexible and wearable sensors

Flexible and wearable sensors have drawn ex-tensive concern due to their wide potential applications inwearable electronics and intelligent robots. Flexible sensorswith high sensRivity, good flexibility, and excellent stabilityare highly desirable for monitoring human biomedical signals,movements and the environment. The active materials and thedevice structures are the keys to achieve high performance.Carbon nanomaterials, including carbon nanotubes （CNTs）,graphene, carbon black and carbon nanofibers, are one of themost commonly used active materials for the fabrication ofhigh-performance flexible sensors due to their superiorproperties. Especially, CNTs and graphene can be assembledinto various multi-scaled macroscopic structures, includingone dimensional fibers, two dimensional films and three di-mensional architectures, endowing the facile design of flexiblesensors for wide practical applications. In addition, the hybridstructured carbon materials derived from natural bio-mate-rials also showed a bright prospect for applications in flexiblesensors. This review provides a comprehensive presentation offlexible and wearable sensors based on the above variouscarbon materials. Following a brief introduction of flexiblesensors and carbon materials, the fundamentals of typicalflexible sensors, such as strain sensors, pressure sensors,temperature sensors and humidity sensors, are presented.Then, the latest progress of flexible sensors based on carbonmaterials, including the fabrication processes, performanceand applications, are summarized. Finally, the remainingmajor challenges of carbon-based flexible electronics are dis-cussed and the future research directions are proposed.