Prospective Validation of High-Shear Wet Granulation Process by Wet Granule Sieving Method. II. Utility of Wet Granule Sieving Method

The general utility of a method for determination of high-shear wet granulation end point by monitoring the wet granule particle size distribution was evaluated. Wet granulation was conducted in a 25-liter high-shear mixer using four model drugs with different solubilities and particle sizes (ethenzamide, unmilled and milled acetaminophen, and antipyrine). For each drug formulation, its wet granule particle size fraction and target range for granulation end point determination were selected based on the tablet characteristics that are known to be influenced by the wet granulation process. Granules manufactured under different conditions (i.e., different main and chopper blade speeds and binder supplying rate) but manufactured to the same granulation end point determined by the selected fraction and range showed very similar granule characteristics and subsequently very similar tabler characteristics. From the fact that there was a good correlation between the wet and dry-sized granule particle size distributions even if the drying method was changed from fluid-bed drying to vacuum drying, the general application of the end point determining method was verified. Further, the method was shown to be sensitive to the critical granulation parameters for granulation progression and to be very capable of determining the granulation extent. Thus, it was suggested that the method is applicable to various drugs and formulations for determination of wet granulation end point.     

Effects of tungsten addition on tensile properties of a refractory Nb−18Si−10Ti−10Mo−<Emphasis Type="Italic">x</Emphasis>W (<Emphasis Type="Italic">x</Emphasis>=0,5, 10 and 15 mol.%)<Emphasis Type="Italic">in-situ</Emphasis> Composites at 1670 K

To investigate the effect of tungsten addition on mechanical properties, we prepared refractory (62−x)Nb−18Si−10Mo−10Ti−xW (x=0, 5, 10 and 15 mol.%)in-situ composites by the conventional arc-casting technique, and then explored the microstructure, hardness and elastic modulus at ambient temperature and tensile properties at 1670 K. The microstructure consists of relatively fine (Nb, Mo, W, Ti)₅Si₃ silicide and a Nb solid solution matrix, and the fine eutectic microstructure becomes predominant at a Si content of around 18 mol.%. The hardness of (Nb, Mo, W, Ti)₅Si₃ silicide in a W-free sample is 1680 GPa, and goes up to 1980 GPa in a W 15 mol.% sample. The hardness, however, of Nb solid solution does not exhibit a remarkable difference when the nominal W content is increased. The elastic modulus shows a similar tendency to the hardness. The optimum tensile properties of the composites investigated are achieved at W 5 mol.% sample, which exhibits a relatively good ultimate strength of 230 MPa and an excellent balance of yield strength of 215 MPa, and an elongation of 3.7%. The SEM fractography generally indicates a ductile fracture in the W-free sample, and a cleavage rupture in W-impregnated ones.     

离心模型试验模拟平板载荷试验研究

利用承载力离心模型试验研究平板载荷试验中的承压板尺寸对承载力取值的影响。试验结果表明:基础直径为80 cm和56 cm时的极限承载力相差达27%～40%;在疏松地基(相对密度为34%)情况下,可忽略基础尺寸效应对试验结果的影响。但是在密实地基(相对密度为78%)情况下,《建筑地基基础设计规范》(GB50007-2002)规定的承压板尺寸范围内(56～80 cm)仍然存在基础尺寸效应,即使是80 cm的承压板,其承载力系数达到可忽略尺寸效应时对应的承载力系数的1.2倍。基于离心模型试验结果,提出基础尺寸效应修正式和承压板尺寸换算式,对平板载荷试验结果进行修正。     

天然边坡削坡工程中的稳定性研究

天然边坡在削坡工程施工阶段或竣工后,往往形成上下部不同坡度的边坡。离心模型试验与现场试验结果表明,这类边坡有两种破坏模式。一种是滑裂面始于坡顶,另一种是滑裂面始于坡面。利用极限分析上限法理论讨论并确定边坡发生不同破坏模式的条件,从而给出极限开挖深度、设计开挖深度小于极限开挖深度时的稳定安全系数以及设计开挖深度大于极限开挖深度时的土压力,为解决天然边坡削坡工程中的稳定性设计问题提供理论依据。     

Direct measurement of energetic electron flow in Q-shu University experiment with steady-state spherical tokamak

In magnetized plasmas, the presence of a significant number of energetic electrons has been observed but quantitative characteristics of these electrons are proving difficult to investigate. A Langmuir probe offers a means to provide quantitative measurement of these energetic electrons that takes into account electron emissions (secondary electron emission and electron reflection) from the probe tips and sheath expansion around the probe tips caused by a considerable negative potential. In this paper, these effects are experimentally confirmed and an analytical means to measure energetic electron characteristics are proposed. An analysis of plasmas produced by a high frequency wave is then applied leading to the successful detection of an asymmetric flow of energetic electrons. The estimated electron temperature and current density were approximately 4-5 keV and 2-3 kA/m(2).     

Development of Flexible Piezoelectric Strain Sensor Array

In this paper, we present a novel flexible sensor array manufacturing process that involves transfer printing methods using a chip mounter with a vacuum collet. We successfully transfer‐printed continuously very fragile microelectromechanical systems (MEMS)‐based 5‐mm‐long, 1‐mm‐wide, 5‐μm‐thick high‐aspect‐ratio ultrathin PZT (1.9 μm)/Si (3 μm) strain sensors onto a polyimide based flexible printed‐circuit (FPC) substrate with etched Cu wiring. Then, we connected the sensors to the Cu wiring by printing insulating and conductive pastes using a screen printer. The output voltage based on the deformation behavior of the test plate was generated from the flexible piezoelectric strain sensor array attached to the plate. Therefore, the developed piezoelectric sensor array is capable of easily performing the distribution measurement of the strain leading to damage such as cracks.     

Formation of a High Conductivity Fuel Cell Electrolyte by Pressing Diphenylsiloxane-Based Inorganic–Organic Hybrid Particles

An inorganic–organic nanohybrid particle with a two-dimensional chain structure, diphenylsiloxane-silica (Ph₂SiO–SiO₂), was prepared by sol–gel process using diphenyldiethoxysilane (DPDES) and tetraethoxysilane (TEOS), and a high proton conducting polymer of poly(2-acrylamido-2-methyl-1-propane sulfonic acid) (PAMPS) was deposited on the Ph₂SiO–SiO₂ particles via layer-by-layer assembly. A flexible sheet-like electrolyte was successfully obtained from the resulting PAMPS-deposited particles by pressing. The proton conductivity of the sheet prepared using unmodified Ph₂SiO–SiO₂ particles was lower than 10⁻⁹ S/cm at 80°C. On the other hand, the PAMPS-deposited samples showed proton conductivities ∼7 orders of magnitude higher than those of the sample prepared using unmodified particles, and their conductivity reached about 1 × 10⁻² S/cm at 80°C and 80% relative humidity. This is ascribed to the PAMPS layer being concentrated at the particle interfaces, which percolated throughout the monolithic sample.     

Long-term reading experiment on a photorefractive holographic memory with the hologram sustainment technique by optical feedback

We demonstrate a long-term continuous readout of a two-dimensional image in a photorefractive holographic memory with a BaTiO₃ crystal. A considerable extension of reading time is achieved by use of a hologram sustainment technique with an optical feedback circuit. Hologram rewritings by the simultaneous illumination of the reading beam and the feedback beam, which is incident on a crystal from the opposite direction to the reading beam, contribute to all-optical hologram sustainment without any fixing technique. In this paper, the effectiveness of the hologram sustainment technique is explained by the analysis of the temporal property of the amplitude of the index grating in a crystal. By calculating the temporal properties of the reconstructed beam intensity, we reveal the feedback rate and the coupling strength for high output efficiency. We perform an experiment on two-dimensional image reading and writing with a 45° cut BaTiO₃ crystal and show that a recorded image can be reconstructed over 20?min without critical image degradation whereas a reconstructed image fades away within 20?s in the conventional readout technique.     

Sc(OTf)3-catalyzed Cyclooligomerization of 2,4-Dialkoxybenzyl Alcohols. Formation of Resorcin[n]arene Peralkyl Ethers

Summary The cyclooligomerization of 2,4-dialkoxybenzyl alcohols 3 catalyzed by Sc(OTf)₃ in CH₃CN under high dilution conditions produced a series of resorcin[n]arene peralkyl ethers containing four to nine resorcinol units. When the reactions were conducted at 50°C, the cyclic tetramers 4, which are thermodynamically favored products, are selectively formed in good yields. It is noteworthy that the reaction of 2,4-dimethoxybenzyl alcohol 3d at 0°C produced the corresponding cyclic octamer 8d as the major product. In other cases, such as the selective formation of a cyclic octamer could not be observed. This selective formation of 8d is due to a combination of the reversibility of the oligomerization in the presence of 3d and the insolubility of the octamer in the reaction medium. The conformational analysis of these cyclic oligomers was done by variable temperature ¹H NMR spectroscopy.