脉冲激光沉积法在多孔硅衬底上制备ZnS薄膜

用电化学阳极氧化法制备了一定孔隙率的多孔硅样品,然后用脉冲激光沉积法以PS为衬底生长一层ZnS薄膜.用X射线衍射仪、扫描电子显微镜和荧光分光光度计分别表征了ZnS薄膜的结构、形貌和ZnS/PS复合膜的光致发光性质.XRD结果表明,制备的ZnS薄膜沿β-ZnS(111)方向择优生长,结晶质量良好,但衍射峰的半峰全宽较大;SEM图像显示,ZnS薄膜表面出现一些凹坑,这是衬底PS的表面粗糙所致.室温下的光致发光谱表明,沉积ZnS薄膜后,PS的发光峰蓝移.把ZnS的蓝绿光与PS的橙红光叠加,在可见光区450~700 nm形成了一个较宽的光致发光谱带,ZnS/PS复合膜呈现较强的白光发射.     

Changes of paired-pulse evoked responses during the development of epileptic activity in the hippocampus

Dysfunction of inhibitory synaptic transmission can destroy the balance between excitatory and inhibitory synaptic inputs in neurons, thereby inducing epileptic activity. The aim of the paper is to investigate the effects of successive excitatory inputs on the epileptic activity induced in the absence of inhibitions. Paired-pulse orthodromic and antidromic stimulations were used to test the changes in the evoked responses in the hippocampus. Picrotoxin (PTX), γ-aminobutyric acid (GABA) type A (GABA_A) receptor antagonist, was added to block the inhibitory synaptic transmission and to establish the epileptic model. Extracellular evoked population spike (PS) was recorded in the CA1 region of the hippocampus. The results showed that the application of PTX induced a biphasic change in the paired-pulse ratio of PS amplitude. A short latency increase of the second PS (PS2) was later followed by a reappearance of PS2 depression. This type of depression was observed in both orthodromic and antidromic paired-pulse responses, whereas the GABAergic PS2 depression [called paired-pulse depression (PPD)] during baseline recordings only appeared in orthodromic-evoked responses. In addition, the depression duration at approximately 100 ms was consistent with a relative silent period observed within spontaneous burst discharges induced by prolonged application of PTX. In conclusion, the neurons may ignore the excitatory inputs and intrinsically generate bursts during epileptic activity. The depolarization block could be the mechanisms underlying the PPD in the absence of GABA_A inhibitions. The distinct neuronal responses to stimulations during different epileptic stages may implicate the different antiepileptic effects of electrical stimulation.     

Optimization of biotransformation from phytosterol to androstenedione by a mutant Mycobacterium neoaurum ZJUVN-08

Biotransformation of phytosterol(PS) by a newly isolated mutant Mycobacterium neoaurum ZJUVN-08 to produce androstenedione has been investigated in this paper.The parameters of the biotransformation process were optimized using fractional factorial design and response surface methodology.Androstenedione was the sole product in the fermentation broth catalyzed by the mutant M.neoaurum ZJUVN-08 strain.Results showed that molar ratio of hydroxypropyl-β-cyclodextrin(HP-β-CD) to PS and substrate concentrations were the two most significant factors affecting androstenedione production.By analyzing the statistical model of three-dimensional surface plot,the optimal process conditions were observed at 0.1 g/L inducer,pH 7.0,molar ratio of HP-β-CD to PS 1.92:1,8.98 g/L PS,and at 120 h of incubation time.Under these conditions,the maximum androstenedione yield was 5.96 g/L and nearly the same with the non-optimized(5.99 g/L),while the maximum PS conversion rate was 94.69% which increased by 10.66% compared with the non-optimized(84.03%).The predicted optimum conditions from the mathematical model were in agreement with the verification experimental results.It is considered that response surface methodology was a powerful and efficient method to optimize the parameters of PS biotransformation process.     

Development of a miniature silicon wafer fuel cell using L-ascorbic acid as fuel

In the current studies a miniature silicon wafer fuel cell （FC） using L-ascorbic acid as fuel was developed. The cell employs L-ascorbic acid and air as reactants and a thin polymer electrolyte as a separator. Inductively coupled plasma （ICP） silicon etching was employed to fabricate high aspect-ratio columns on the silicon substrate to increase the surface area. A thin platinum layer deposited directly on the silicon surface by the sputtering was used as the catalyst layer for L-ascorbic acid electro-oxidation. Cyclic voltammetry shows that the oxidation of L-ascorbic acid on the sputtered platinum layer is irreversible and that the onset potentials for the oxidation of L-ascorbic acid are from 0.27 V to 0.35 V versus an Ag/AgCl reference electrode. It is found that at the room temperature, with 1 mol/L L-ascorbic acid/PBS （phosphate buffered solution） solution pumped to the anode at 1 ml/min flow rate and air spontaneously diffusing to the cathode as the oxidant, the maximum output power density of the cell was 1.95 mW/cm^2 at a current density of 10 mA/cm^2.     

Switching Phenomena of CuTCNQ Induced Mainly by the Interaction among Microcrystaline Grains

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反应磁控溅射Cu2 O薄膜的结构和电学性质

用X射线衍射仪检测薄膜的结构;用分光光度计测量薄膜的透射率和反射率,采用拟合正入射透射谱数据的方法计算薄膜的厚度;用Van der Pauw方法测量薄膜表面电阻和霍尔迁移率,并计算出电阻率和载流子浓度.结果表明,生成单相Cu2O薄膜的氧气流量范围很小,在氧气流量为5-7sccm范围,薄膜主要成分为Cu2O,其中氧氩流量比为6∶25时,生成单相多晶结构的Cu2O薄膜,其表面电阻0.68MΩ/□,电阻率58.29Ω.cm,霍尔迁移率4.73cm2·V-1·s-1,载流子浓度3×1016cm-3.     

Characterization of DC magnetron sputtering deposited thin films of TiN for SBN/MgO/TiN/Si structural waveguide

INTRODUCTION Monocrystalline SBN (Strontium barium nio-bium, SrxBa1?xNb2O6, denoted SBNx?100, where 0.25≤x≤0.75) solid solution, is currently being inves-tigated as potential material for many micro-device applications, such as piezoelectric infrared detectors, piezoelectric, electro-optic modulators, and holo-graphic storage (Koch et al., 1998), because SBN has one of the largest known linear electro-optic coeffi-cients (r33=1300 pm/V for SBN75), two orders of magnitude larger th…     

Dependence of electrical and optical properties of IGZO films on oxygen flow

Amorphous InGaZnO (a-IGZO) films were deposited on the corning eagle XG (EXG) glass substrates using magnetron sputtering method. The structure, surface morphology, electrical and optical properties of these films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), semiconductor parameter analyzer and spectrophotometry, respectively. The influence of oxygen flow on the electrical properties of IGZO thin films was studied, showing that increasing oxygen flow changes the resistivity with six orders of magnitude. The contact resistance of ITO/IGZO is 7.35×10⁻² Ω·cm², which suggests that a good ohmic contact exists between In₂O₃: Sn (ITO) and IGZO film.     

ALTER FPGA器件的配置模式及其实现方法

介绍了基于SRAM技术的ALTERA FPGA系列器件的配置模式,着重讨论了其中两种配置模式:PS模式和JTAG模式,并且设计了一个适配电路,不管FPGA器件是以PS模式连接还是以JTAG模式连接,该适配电路都能对FPGA器件进行正确无误的配置。     

Effects of worked examples, example-problem, and problem-example pairs on novices’ learning

Research has demonstrated that instruction that relies more heavily on example study is more effective for novices’ learning than instruction consisting of problem solving. However, ‘a heavier reliance on example study’ has been implemented in different ways. For example, worked examples only (WE), example-problem pairs (WE-PS), or problem-example pairs (PS-WE) have been used. This study investigated the effectiveness of all three strategies compared to problem solving only (PS), using electrical circuits troubleshooting tasks; participants were secondary education students who were novices concerning those tasks. Based on prior research, it was hypothesized and confirmed that WE and WE-PS would lead to lower cognitive load during learning and higher learning outcomes than PS. In addition, the open questions of whether there would be any differences between WE and WE-PS, and whether there would be any differences between PS-WE and PS were explored. Results showed no differences between WE and WE-PS or between PS-WE and PS. This study can inform instructional designers on which example-based learning strategies to implement: it does not seem necessary to alternate example study and problem solving, but when doing so, example-problem pairs should be used rather than problem-example pairs.     

利用KCl／Al作为电极的有机电致发光器件

制备了利用KCl／Al作为负电极的有机电致发光器件,器件结构为IT0／NPB／Alq／KCl／Al,KCl层的加入增强了电子注入,当其厚度为1．5nm时,器件的性能最好．与单层Al电极的同类器件相比,此时器件的开启电压由Al电极时的5V降低到了2．5V。器件的亮度在11V时由231cd／m^2提高到15070cd／m^2,器件的发光效率也增加了10倍,达到2．79cd／A．     

绒面结构对低成本多晶硅太阳电池性能的影响

采用化学腐蚀法在多晶硅材料的表面制备了绒面结构,腐蚀液包括富HF的HNO3-HF-H2O溶液,富HNO3的HNO3-HF-H2O溶液和3％的碱腐蚀液.通过表面形貌SEM、反射谱和少子寿命的测试,详细地研究了不同腐蚀液制备的绒面的形貌、光学特征和少子寿命.最后在绒面的基础上制备了低成本多晶硅太阳电池,分析了绒面结构对电池性能的影响.结果表明,经过富HF的HNO3：HF：H2O溶液腐蚀后制备的低成本多晶硅电池的效率高于经其他两种腐蚀后所制备的电池效率.     

掺铝氧化锌薄膜的湿化学腐蚀特性研究

利用射频磁控溅射制备AZO薄膜,然后在常温下0.1%的盐酸水溶液中对薄膜进行化学腐蚀,系统研究了腐蚀时间长短对薄膜的表面形貌和光电学性质的影响。结果表明,薄膜表面的粗糙度和方块电阻随腐蚀时间的增加而增大;薄膜的光学透射率和反射率均随腐蚀时间的增加而减小。     

Modeling of tool-chip contact length for orthogonal cutting of Ti-6Al-4V alloy considering segmented chip formation

In this work, the orthogonal cutting experiments on Ti-6Al-4V alloy were conducted at different cutting speeds(10—160 m/min)and feed rates(20—160 μm/rev). The tool-chip contact length was measured by the track of tool rake face; meanwhile, the chip morphology caused by the localized and overall chip deformation was characterized by the degree of segmentation and the chip compression ratio, respectively. These parameters were analyzed and calculated according to the segmented chip morphology. In addition, three modified models considering the overall chip deformation and the localized deformation of adiabatic shear band were proposed, and the constants of the models were calculated by the genetic algorithm optimization. Considering the overall and localized chip deformation, the value and variation trend of the tool-contact length predicted by these three models agreed well with the experimental results.     

Optical and Irradiation-Resistant Properties of ITO Films on F46 and PI Substrates

This study investigated indium tin oxide(ITO) films that were deposited on fluororesin-46(F46) and polyimide(PI) transparent flexible substrates by a DC magnetron sputtering system. The optical properties of ITO films on F46 and PI including transmittance and reflectance in visible, near-infrared, and infrared spectral regions were obtained, and the surface morphology, and optical and electrical properties of ITO/F46 and ITO/PI after vacuum ultraviolet irradiation were investigated. The results showed that the mean transmittances of ITO/F46 and ITO/PI decreased and the sheet resistance increased after the irradiation, and these effects were mainly attributed to the greater surface roughness and crystal defects caused by the irradiation.     

立方形锰氧化物的制备及其电容特性研究

目的 :制备立方形锰氧化物高电容超级电容器材料。方法:采用水热结合热分解的方法,制备结构均一的锰氧化物的立方体结构;利用X射线衍射仪(XRD)、扫描电镜(SEM)、透射电镜(TEM)等方法对样品进行了微观表征,使用自制的三电极体系对电极材料进行了循环伏安(CV)、充放电性能和循环稳定性研究。结果:检测结果显示,所制备的立方体结构是由一个个约为10 nm的小颗粒自组装形成的,颗粒之间具有丰富的微孔结构。电化学测试显示在电流密度为1 A/g下,担载量为2 mg/cm2的条件下,电极材料的放电比容量高达318 F/g,其作为正极材料具有比较好的电容特性。结论:此方法制备过程简单,容易工业化生产,该立方形的锰氧化物较适合作为超级电容器的正极材料。     

Surface pattern based on an azobenzene-containing copolymer thin film and its light-driven morphology modulation

A type of azobenzene-containing block copolymer polymethyl methacrylate-b-poly (n-butylmethacrylate-co-6-(4-(phenylazo) benzoate) hexyl methacrylate) (PMMA-b-(PnBMA-co-PAzoMA)) was synthesized by the atom transfer radical polymerization (ATRP). Macroinitiator polymethyl methacrylate (PMMA) was prepared by ATRP and used to initiate the copolymerization of monomer n-butyl methacrylate (nBMA) and azobenzene-based methacrylate monomer (AzoMA). Herein, three block copolymers with different molecular weights and block volume fractions were obtained and spin-coated on a silicon substrate or quartz plate before annealing at 180 °C for 14 h. The surface morphologies in these annealed copolymer films were observed by atomic force microscopy (AFM). Bicontinuous stripe or island patterns with different sizes were formed dependent on the film thickness. These ordered patterns are considered to be formed arising from the dewetting process of the surface layer in the copolymer film. Photoisomerization of azobenzene units in the copolymer films changed the dewetting behaviors of the surface layer of the thin film. Therefore, some copolymer annealed films showed a reversible morphology conversion between bicontinuous stripe and island structure when exposed to UV light and upon being stored in the dark. It was found that the composition of the block copolymer had obvious influences on the photoinduced morphology conversion behaviors in these copolymer thin films. When the volumes of PnBMA and PAzoMA phases in the block copolymer were large enough, the surface morphology could be modulated by UV light irradiation and storage in the dark. This work proposes a new possibility for photoinduced control and design of the dewetting processes of thin films using a linear block copolymer.     

Calcium Phosphate Coating on Al2O3 Ceramics by a Biomimetic Method Using Electric Pulse Technique

The preparation of calcium phosphate (CP) coating on alumina ceramics using electric pulse stimulating method has been investigated. The cup-shaped alumina ceramics were soaked in a simulated body fluid ( SBF), and a square pulse potential with frequency of 1 Hz and voltage of 110 V was applied between the inner and outer surfaces of the alumina cup. Surface morphology of CP coatings during different deposition periods was observed by a Philips XL-30 scanning electron microscope (SEM). Compositional analysis was examined by EDAX. The mechanism of nucleation and growth of CP coating was discussed. SEM result indicates that the coating comprises of a large number of tiny needle-like grains and has a porous microstructure. There is a strong bond between the deposited layer and Al2O3 substrate, which may be due to the gentle growth of the biomimetic method. The EDAX analysis indicates that main composition of the coating is calcium and phosphor. The formation of CP coating may be contributed to the stimulation of electric pulse and the high ions concentration which is 1.5 times of the concentration of SBF solution ( 1.5SBF solution). Such surface functionalization method by electric pulse potential can be used to prepare CP coating on various electric-insulating bioinert materials for improving their bioactive character.     

Effect of deposition parameters on mechanical properties of TiN films coated on 2A12 aluminum alloys by arc ion plating (AIP)

1 Introduction Weight saving materials such as aluminum and its alloys are becoming increasingly important and have been attracting increasing attention over the past decade, specially in the automotive, aerospace and chemical industries, and electrical devices because of their high strength-to-weight ratio, high electrical and thermal conductivities, processability and recyclability and good resistance to degradation in some corrosive environments [1,2]. In the automotive industry, there is d…     

碳纳米点的制备及其非线性光限幅性能研究

以肝素钠为碳源,通过水热合成法制备碳纳米点（CNDs）,对所制得的CNDs形貌、组成及线性光学性能进行系统研究。结果表明,CNDs粒径均一,且表面富含羧基和羟基等官能团;在270 nm处有明显的紫外吸收峰。CNDs具有与激发波长相关的荧光特性,发射峰随激发波长增大的而红移。采用开孔Z-扫描法探索CNDs的非线性光学效应,结果表明,CNDs具有与能量相关的从饱和吸收向反饱和吸收转变的特性,其非线性吸收系数β和饱和能量IS分别为1.4×10^-11m/W和8×10¹⁰W/m²。