Crystal Facet Engineering of Single-Crystalline TiC Nanocubes for Improved Hydrogen Evolution Reaction

Single-crystalline {100} faceted TiC is of great significance in theory to a large number of engineering applications owing to its extraordinary catalytic properties. However, the {111} planes are prevalent in conventional TiC powders given their favorable thermodynamic stability during the initial low stoichiometric growth stage. Herein, a disproportionation–decomposition strategy is developed to directly produce Ti and C atoms to synthesize single-crystalline {100} faceted TiC powders. Outstanding electrochemical performance of TiC {100} crystal planes in terms of the hydrogen evolution reaction is evidenced by an overpotential of 392 mV at 10 mA cm⁻², which is 52% lower than that of randomly faceted TiC counterparts (815 mV).     

ZnO/PS异质结的光学和电学性质

用脉冲激光沉积的方法在多孔硅(PS)衬底上沉积ZnO薄膜,在室温下测量了ZnO/PS异质结的结构及光学和电学性质.X射线衍射仪和扫描电子显微镜测量表明,制备的ZnO薄膜具有一定的c轴取向,但薄膜存在较多缺陷.光致发光谱显示,PS的发光与ZnO的发光相叠加,呈现白光发射.对异质结I-V特性曲线的测量表明,异质结呈现出与普通二极管不同的整流特性,其反向电流不饱和,据此提出了能带模型.     

利用星载多波长辐射计观测资料反演大气气溶胶光学厚度

本文提出了一个利用星载多波长辐射计的可见光和近红外通道观测资料反演气溶胶光学厚度的迭代方案。数值试验结果表明，该方案反演气溶胶光学厚度的误差小于10％。将该方案用于分析我国东南沿海上空NOAA－AVHRR观测资料，得到了较为合理的气溶胶光学厚度的空间分布。     

遥感模糊图像分割与像元分析

卫星遥感对地观测获取的图像信息其像元的数据往往是多种地表成分的复合，因此地表反射辐射反映在像元上带有一定的模糊性，基于模糊数学的理论和方法，同时利用了ＴＭ（１，２，３，４，５，７）六个波段的数据信息，对一幅图像进行非监督分割，并用模糊算法对单个像元所隶属的各聚类中心的成分进行了数值分析，结果显示出尽管分割后一些像元属同一类别，但其复合成分则不尽相同，该方法对于ＴＭ像元分析精度的可靠性有待地面工作的     

遥感模糊图像分割与像元分析

卫星遥感对地观测获取的图像信息其像元的数据往往是多种地表成分的复合，因此地表反射、辐射反映在像元上就带有一定的模糊性。基于模糊数学的理论和方法，同时利用了TM（1，2，3；4，5，7）对六个波段的数据信息，对一幅图像进行非监督分割，并用模糊算法对单个像无所隶属的各聚类中心的成分进行了数值分析。结果显示出尽管分割后一些像元属同一类别，但其复合成分则不尽相同。该方法对于TM像无分析精度的可靠性有待地面工作的进一步验证。     

Stress field and failure probability analysis for the single cell of planar solid oxide fuel cells

An analytical model is developed to predict the residual thermal stresses in a single cell of solid oxide fuel cells (SOFCs), which consists of a thick porous 8 mol% Y₂O₃ stabilized zirconia/nickel oxide (8YSZ/NiO) anode, a dense 8YSZ electrolyte and a porous lanthanum strontium manganite (LSM) cathode. The simulated stresses in the cell at room temperature, which are resulted from the contraction mismatch of its components, indicate that the major principal stress in the anode is tensile while the electrolyte and cathode are under compressive stresses. The stress in one component decreases with the increase of its thickness when the thicknesses of the other two components are fixed, and the decrease of the tensile stress in the anode will cause the increase of the compressive stresses in both the cathode and the electrolyte, and vice versa. The analysis also reveals that the anode is the part that is most susceptible to fracture since the tensile thermal stress is so high that it reaches to the fracture strength of the anode material. The Weibull statistic is employed to estimate the failure probability of the anode. The simulation results indicate that the anode failure probability decreases with the increase of the anode thickness and the decrease of the electrolyte thickness. To keep the anode failure probability less than 1E−06, the anode thickness should be greater than 0.7 mm for a cell with an electrolyte thickness of 10 μm and a cathode thickness of 20 μm.     

Shear elastic modulus estimation from indentation and SDUV on gelatin phantoms

Tissue mechanical properties such as elasticity are linked to tissue pathology state. Several groups have proposed shear wave propagation speed to quantify tissue mechanical properties. It is well known that biological tissues are viscoelastic materials; therefore, velocity dispersion resulting from material viscoelasticity is expected. A method called shearwave dispersion ultrasound vibrometry (SDUV) can be used to quantify tissue viscoelasticity by measuring dispersion of shear wave propagation speed. However, there is not a gold standard method for validation. In this study, we present an independent validation method of shear elastic modulus estimation by SDUV in three gelatin phantoms of differing stiffness. In addition, the indentation measurements are compared to estimates of elasticity derived from shear wave group velocities. The shear elastic moduli from indentation were 1.16, 3.40, and 5.6 kPa for a 7%, 10%, and 15% gelatin phantom, respectively. SDUV measurements were 1.61, 3.57, and 5.37 kPa for the gelatin phantoms, respectively. Shear elastic moduli derived from shear wave group velocities were 1.78, 5.2, and 7.18 kPa for the gelatin phantoms, respectively. The shear elastic modulus estimated from the SDUV, matched the elastic modulus measured by indentation. On the other hand, shear elastic modulus estimated by group velocity did not agree with indentation test estimations. These results suggest that shear elastic modulus estimation by group velocity will be bias when the medium being investigated is dispersive. Therefore, a rheological model should be used in order to estimate mechanical properties of viscoelastic materials.     

利用MODIS数据对北极夏季卷云特性的研究

利用2011~2014年MODIS云产品数据对北极地区夏季卷云的出现概率、云顶温度、云顶高度、光学厚度、有效粒径大小进行统计分析,并讨论了北极地区夏季卷云有效粒径大小和卷云高度的关系。结果表明,北极地区上空夏季卷云出现概率最高,水云较少。卷云云顶温度主要分布在230~272 K(即-43~-5℃),其云顶高度主要在2~8 km,4.5~6 km出现概率最大。卷云的光学厚度主要在小于10范围内。卷云的有效粒径在5~40 m之间,10~20 m出现概率最大。卷云的有效粒径和高度的关系与中纬度地区相反,北极地区卷云高度越高,卷云有效粒径越大。北极地区卷云随着纬度增大,卷云出现概率增加,卷云云顶温度降低,卷云高度增加,卷云有效粒径增大,卷云光学厚度增大。     

White light photoluminescence from ZnS films on porous Si substrates

ZnS films were deposited on porous Si (PS) substrates using a pulsed laser deposition (PLD) technique.White light emission is observed in photoluminescence (PL) spectra, and the white light is the combination of blue and green emission from ZnS and red emission from PS. The white PL spectra are broad, intense in a visible band ranging from 450 to 700 nm. The effects of the excitation wavelength, growth temperature of ZnS films, PS porosity and annealing temperature on the PL spectra of ZnS/PS were also investigated.     

静乐黑枸杞花青素的纯化及其抗氧化特性

目的:探讨静乐黑枸杞花青素的纯化工艺及其抗氧化活性.方法:比较HPD100、D101、NKA、AB-8、HPD400等五种树脂对静乐黑枸杞花青素的吸附与解析性能,筛选最佳树脂,并优化其纯化条件;采用DPPH自由基、OH自由基和ABTS自由基法,比较黑枸杞样品纯化前后的抗氧化活性.结果:HPD100大孔树脂对于静乐黑枸杞...