甚高频等离子体增强化学气相沉积制备微晶硅太阳电池的研究

采用甚高频等离子体增强化学气相沉积技术成功地制备了不同硅烷浓度和辉光功率条件下的微晶硅电池.电池的J-V测试结果表明：在实验的硅烷浓度和功率范围内，随硅烷浓度的降低和功率的加大，对应电池的开路电压逐渐变小；硅烷浓度的不同对电池的短路电流密 度有很大的影响，但功率的影响在实验研究的范围内不是很显著.对于微晶硅电池，N层最好 是非晶硅，这是因为一方面可以降低对电流的横向收集效应，另一方面也降低了电池的漏电概率，提高了电池的填充因子. 关键词： 微晶硅太阳电池 甚高频等离子体增强化学气相沉积     

基于倏逝波的光纤生物传感器研究

构建了一种以光纤束作为激发光信号和荧光信号传输通道的光纤生物传感器结构.根据光纤探针的倏逝波理论和模式匹配理论对光纤探针的几何形状进行了设计,制作了数组光纤探针并根据需要对其中一部分进行荧光标记.选择了光纤探针置于空气中和水溶液中两种情况,对光纤传感器系统进行了信号检测实验,对比标记了的和未标记的相同几何结构参数的光纤探针两者在系统中被探测的信号差异.从二者的差别区分出系统所探测的倏逝波激发的荧光信号,证明了该光纤传感器系统的可行性.     

Polymer-assisted complexing controlled orientation growth of ZnO nanorods

The growth of the oriented zinc oxide (ZnO) nanorods on silicon substrates based on a simple novel chemical transformation and thermal hydrolysis by using polyvinyl alcohol (PVA) as self-assembling complex polymer was introduced in this paper. All the polymers were removed after chemical oxidation and only the carbonized grid backbones remained that confines the ZnO nanorod’s diameter and enhance the absorption and diffusion of ZnO at the tips of the nanorods during growth. The ZnO nanorods are investigated by FTIR, XRD and FE-SEM. The results indicated that these nanorods have fine hexagonal wurtzite crystal structure and their diameter varies from 20 to 90 nm and the length up to about 1 μm. A polymer-localized ZnO growth model is proposed, which well explains the growth behavior of ZnO nanorods.This revised version was published online in August 2005 with a corrected issue number.     

基于AMESim的制动钳动态所需液量检测仿真研究

制动钳所需液量检测是制动钳性能检测中十分重要的一部分,目前关于制动钳动态所需液量检测研究缺乏理论和仿真依据,无法结合实际检测实现制动钳故障诊断,针对这一问题,在研究主缸位移差值法动态所需液量检测系统数学模型的基础上搭建AMEsim仿真模型,对主缸活塞速度和钳体结构因素进行仿真分析,并通过实验验证模型的正确性。结果表明：主缸活塞速度对动态所需液量检测影响较小;回位弹簧刚度、制动间隙和摩擦块、橡胶密封圈硬度对动态所需液量曲线有不同程度的影响,可以根据曲线特征实现制动钳故障诊断。     

Spectral line suppression and sideband narrowing via quantum interference

We reveal that for a realistic system, interference effects are obtained such as the suppression of central line and inner sidebands and the narrowing of the outer fluorescence sidebands. For this purpose, we consider a spontaneous decay from an excited state to a metastable state when the excited and metastable states are resonantly coupled to an auxiliary metastable state by a laser field and a microwave field, respectively. The fluorescence spectrum evolves from a five-peaked structure into a doublet of ultrasharp lines as the ratio of the laser field Rabi frequency to the microwave Rabi frequency is decreased. The physical origin is presented in terms of dressed states.     

4.44 W of CW 515 nm green light generated by intracavity frequency doubling Yb:YAG thin disk laser with LBO

We demonstrate the generation of 515 nm green laser with diode-pumped Yb:YAG thin disk by intracavity frequency doubling of type-I phase-matched LiB₃O₅(LBO) in a V-type cavity at room temperature. A continuous-wave (CW) output power of 4.44 W at 515 nm was obtained. Optical-optical efficiency of 515 nm green laser is 14.6%. The fluctuation of green laser was 1.6% at the maximum output power in 0.5 h. Thermal lensing effects in Yb:YAG thin disk are investigated too.     

Saturation field direction dependence of domain structures in NiFe elements

The domain structures in NiFe elements were studied by magnetic force microscopy measurement and micromagnetic modeling. The remanent states in the elements were dependent on the direction of the saturation field. The “S” and “U” states were observed at remanence by applying the saturation field at different directions. The “S” and “U” states are metastable: magnetic force microscopy tip field-induced switching from the “S” and “U” states to the flux closure configuration was observed.     

Temperature-insensitive fiber Bragg grating dynamic pressure sensing system

Temperature-insensitive dynamic pressure measurement using a single fiber Bragg grating (FBG) based on reflection spectrum bandwidth modulation and optical power detection is proposed. A specifically designed double-hole cantilever beam is used to provide a pressure-induced axial strain gradient along the sensing FBG and is also used to modulate the reflection bandwidth of the grating. The bandwidth modulation is immune to spatially uniform temperature effects, and the pressure can be unambiguously determined by measuring the reflected optical power, avoiding the complex wavelength interrogation system. The system acquisition time is up to 85 Hz for dynamic pressure measurement, and the thermal fluctuation is kept less than 1.2% full-scale for a temperature range of -10 degrees C to 80 degrees C.     

Biodegradable cystamine spacer facilitates the clearance of Gd(III) chelates in poly(glutamic acid) Gd-DO3A conjugates for contrast-enhanced MR imaging

Poly(L-glutamic acid) (PGA)-cystamine-[gadolinium (Gd)-DO3A] was prepared in high yield with a high Gd-DO3A conjugation efficiency. Approximately 55% of the carboxylic groups in PGA were loaded with Gd-DO3A via cystamine as the spacer. Cystamine can be readily cleaved by endogenous thiols to release the Gd(III) chelates from the conjugate facilitating Gd(III) excretion after the magnetic resonance imaging (MRI). The contrast-enhanced MRI with PGA-cystamine-(Gd-DO3A) was investigated in mice bearing MDA-MB-231 breast carcinoma xenografts. PGA-1,6-hexanediamine-(Gd-DO3A), a paramagnetic polymer conjugate of a nondegradable spacer, was used as a control. Both conjugates resulted in similar contrast enhancement in the heart, vasculature, liver and kidneys in the first hour post injection. More substantial signal intensity reduction was observed for PGA-cystamine-(Gd-DO3A) in these organs than PGA-1,6-hexanediamine-(Gd-DO3A) due to release of the Gd chelates from PGA-cystamine-(Gd-DO3A) after the cleavage of the disulfide spacer by the endogenous thiols. Both conjugates resulted in similar tumor enhancement with approximately 70% increased signal intensity in the tumor periphery and 10-40% increased signal intensity in tumor interstitium. No cross-reaction was observed between PGA-cystamine-(Gd-DO3A) and human serum albumin, a plasma protein containing a cysteine residue. PGA-cystamine-(Gd-DO3A) resulted in significantly lower Gd(III) tissue retention than PGA-1,6-hexanediamine-(Gd-DO3A) 10 days after the injection in the mice (P<.05). The conjugation of Gd(III) chelates to biomedical copolymers via the degradable disulfide spacer resulted in significant contrast enhancement in the blood pool and tumor tissue but minimal long-term Gd(III) tissue retention.     

Imaging theory of an aplanatic system with a stratified medium based on the method for a vector coherent transfer function

A simple formalism relating image fields to object fields, similar to that of the scalar and paraxial case, is presented for an aplanatic system obeying the sine condition, which shows that the vector plane-wave spectrum of image fields is equal to the product of the vector coherent transfer function due to the x- and y-polarized point electric field source and the scalar spectrum of the corresponding transverse object fields. Utilizing this formula and dyadic Green's function, a rigorous imaging theory of an aplanatic system for the point electric current source through a stratified medium is readily developed.