4-D x 3-D ultrasound: real-time scan conversion, filtering, and display of displacement vectors with a motorized curvilinear transducer

Recent research in the field of elastography has sought to expand displacement tracking to three dimensions. Once the 3-D volumes of displacement data have been obtained, they must be scan converted so that further processing, such as inversion methods to obtain tissue elasticity, can take place in Cartesian coordinates. This paper details an efficient and geometrically accurate algorithm to scan convert 3-D volumes of displacement vectors obtained from a motorized sector transducer. The proposed algorithm utilizes the physical scan geometry to convert the 3-D volumes of displacement data to both Cartesian coordinates and Cartesian displacements. Spatially varying filters are also proposed to prevent aliasing while minimizing data loss. Validation of the system has shown the algorithm to be correct to floating point precision, and the 3-D scan conversion and filtering can be performed faster than the native rate of data acquisition for the motorized transducer.     

Preparation and characterization of rare-earth bulks with controllable nanostructures

The preparation and characterization of pure rare-earth-metal bulks with controllable nanostructures are reported in this paper. A novel 'oxygen-free' in?situ synthesis technique that combines inert-gas condensation with spark plasma sintering (SPS) technology is proposed. Taking into account the special mechanisms of SPS consolidation and the scale effects of nanoparticles, we introduced practical procedures for preparing rare-earth bulks of amorphous, mixed amorphous and nanocrystals, and nanocrystalline microstructures, respectively. Compared with the conventional polycrystalline bulk, these nanostructured bulks exhibit substantially improved physical and mechanical properties. This technique enables comprehensive studies on the microstructures and properties of a large variety of nanostructured metallic materials that are highly reactive in the air.     

沉积物中有机碳的直接测定方法

关于区分生油岩和作为生油岩标志的相对数值的方法Philippi已提出过报告。区分的根据是本地原油和运移原油的分异作用。沉积物中有机质的总含量和可抽提烃类的含量,标志着这种分异作用。用以划分生油岩的相对数值是根据可抽提烃类的含量而定的。沉积物中总有机质的测定是一个困难问题,不能根据常规的方法来处理,合理的总有机质含量并不是总有机碳含量。测定碳的方法是根据碳氧化成二氧化碳,然后测定所生成的二氧化碳。文献中所报导的方法主要是关于有机化合物中的总碳和钢铁中碳的方法,大多是在氧气中燃烧氧化成二氧化碳的方法。二氧化碳一般用所产生气体的体积或重量测量。土壤中总碳的测量一般是用重铬酸氧化碳,然后称重所产生的二氧化碳。     

激光准直仪

本文介绍了激光准直仪的特性.研究了激光光轴的稳定性,接收靶类型、方位显示器性能及激光强度稳定性对激光准直仪的影响.测试了准直仪的精度.     

Platinum-gold nanoclusters as catalyst for direct methanol fuel cells

Nanosized platinum-gold alloys clusters have been deposited on gas diffusion electrode by sputter deposition. The deposits were characterized by FE-SEM, TEM and XPS in order to verify the formation of alloy nanoparticles and to study the influence of deposition technique on the nanomorphology. The deposition by sputtering process allowed a uniform distribution of metal particles on porous surface of carbon supports. Typical island growth mode was observed with the formation of a dispersed metal nanoclusters (mean size about 5 nm). Cyclic voltammetry was used to determine the electrochemical active surface and the electrocatalytic performance of the PtAu electrocatalysts for methanol oxidation reaction. The data were re-calculated in the form of mass specific activity (MSA). The sputter-catalyzed electrodes showed higher performance and stability compared to commercial catalysts.     

Electrospun bioactive nanocomposite scaffolds of polycaprolactone and nanohydroxyapatite for bone tissue engineering

Nanocomposite scaffolds based on nanofibrous poly(epsilon-caprolactone) (PCL) and nanohydroxyapatite (nanoHA) with different compositions (wt%) were prepared by electrostatic co-spinning to mimic the nano-features of the natural extracellular matrix (ECM). NanoHA was found to be well dispersed in polymers up to the addition of 20 wt%, after ultrasonication. The composite scaffolds were characterized for structure and morphology using XRD, EDX, SEM, and DSC. The scaffolds have a porous nanofibrous morphology with fibers (majority) having diameters in the range of 450-650 nm, depending on composition, and interconnected pore structures. SEM, EDX, and XRD analyses have confirmed the presence of nanoHA in the fibers. As the nanoHA content in the fibers increases, the surface of fibers becomes rougher. The mechanical (tensile) property measurement of the electrospun composites reveals that as the nanoHA content increases, the ultimate strength increases from 1.68 MPa for pure PCL to 2.17, 2.65, 3.91, and 5.49 MPa for PCL/nanoHA composites with the addition of 5, 10, 15, and 20 wt% nanoHA, respectively. Similarly the tensile modulus also increases gradually from 6.12 MPa to 21.05 MPa with the increase of nanoHA content in the PCL/nanoHA fibers, revealing an increase in stiffness of the fibers due to the presence of HA. DSC analysis reveals that as nanoHA in the composite scaffolds increases, the melting point slightly increases due to the good dispersion and interface bonding between PCL and nanoHA.     

Optical absorption and thermoluminescence in single NaCl:Cu crystals exposed to 60Co and UV light

Optical absorption (OA) and thermally stimulated luminescence measurements were performed on NaCl:Cu+(0.04 and 0.08%) crystals blocks grown by the Czochralski technique. The NaCl:Cu+ crystals were exposed to gamma rays from a 60Co source (0.954-30 kGy) as well as UV radiation. The radiation-induced defects were mainly F, Cu- and Cu+ centres, with absorption bands located at 464, 256.7 and 236 nm, respectively. The absorption bands were found to be independent of the Cu impurity concentration. As the gamma-dose irradiation increased, the absorption band at 256.7 nm decreased while the band at 236.3 nm increased highly along with the 256.7 nm band. The F-centres produced at high gamma-radiation dose while thermally bleached showed an increase of the Cu+ OA bands with a simultaneous decrease of Cu- absorption band. The bleaching with F-light showed the participation of the F centre generated by gamma radiation on the ion valence changes of the doping impurity as well as on the TL phenomenon. The TL measurements in NaCl:Cu crystals with both impurity concentrations demonstrated that the Cu+ concentration has a strong influence on the intensity and shape of the glow peaks.     

加氢裂解的化学

本文评述了烃类催化加氢裂解的化学,还对用双效酸性催化剂的催化加氢裂解及在非酸性金属催化剂上的氢解作用作了比较。用酸性催化剂进行反应的特点是大量的深位的(deep-seated)分子重排,然而总反应是非常特定的和有选择性的,结果是高度地保持了环结构,并得到了高效率支链烷烃及某些环状物。本文还提供典型的环烷烃,芳烃及多环芳烃加氢裂解数据;并探讨了说明产品组成的反应机理。本文也简述了用结晶型硅酸铝催化剂的形状选择(Shape-Selective)催化作用。     

轻薄好色的摩托罗拉C289

不经意地一看，你肯定会以为这是摩托罗拉Ｔ１８９！但当你拿在手里的时候，却会感觉到它比Ｔ１８９轻、薄了许多，而且，屏幕背景色彩与功能菜单项目都显得“与众不同”。它就是摩托罗拉最新推出的Ｃ２８９，也是Ｔ１８９的升级改进版。 Ｃ２８９的菜单界面沿用大家所熟悉的传统摩托罗拉模式，也就是Ｔ１８９／Ｌ２０００／Ｖ９９８＋的模式，全新的功能和菜单项暗藏其中。５０条个性铃声（包括了２０首录音铃声、２０首自编与下载铃声、１０首系统预设铃声），足够让你充分张扬个性和表现自我。其中２０首录音铃声可录制唱片上的一段迷人…