Molybdenum (IV) pyrophosphate isostructural with ZrP2O7

A new molybdenum pyrophosphate, MoP₂O₇, isomorphic with ZrP₂O₇, was prepared at the reductive atmosphere and its magnetic property was measured. The lattice constant of this compound was determined to be $\text{a}\text{=7.952(4)}\text{A}\text{?}$ in the cubic system. A paramgnetic behavior was observed from the liquid N₂ temperature to 500K. The effective magnetic moment for this compound was calculated to be 2.6μ_B in agreement with the calculated spin-only value of 2.83μ_B for Mo⁴⁺.     

Formation and Crystallization in the Yttrium Aluminosilicate Glasses Containing Zinc Oxide

Formation of yttrium aluminosilicate glasses containing zinc oxide from batches melted at 1550°C was investigated. Densities, thermal expansion coefficients, and Vickers hardnesses were measured for some glasses. In a specific compositional region, crystals with a convex and pyramidal habit were observed on the glass surface. The crystal was identified as ZnAl₂O₄ (gahnite) which has a Moh's hardness number of ∼8.     

离散时间MIMO系统极限零点的稳定性

不稳定零点限制了系统可达到的控制性能, 当采用ZOH对一个连续系统进行离散化, 零点的稳定性不能得到保证. 针对无限初等因子次数为2或3时, MIMO系统极限零点的渐近特性和稳定条件不确知问题, 分析了在ZOH条件下, 当采样周期T→0时离散时间系统极限零点的渐近特性, 推导出了关于极限零点稳定性的线性近似公式和保证极限零点稳定的条件, 并给出了详细的证明. 所给出的定理是对Ishitobi定理的进一步扩展.     

Dielectric properties of spark-plasma-sintered BaTiO3

Spark-plasma-sintering (SPS) has been applied to BaTiO₃ to prepare dense ceramics consisting of submicrometre-sized powder. Relatively dense (typically 97% of the theoretical X-ray density) pellets with an average grain size remaining similar to that of the starting powder, approximately 0.6 m, were obtained by the SPS process. Fixed frequency (1 kHz) measurements show the room temperature permittivity of SPS ceramics to be relatively high, approximately 3500, and at least double the value of conventionally sintered ceramics, approximately 1500. Alternating current (a.c.) impedance spectroscopy measurements show that SPS is an effective process to reduce the influence of intergranular (grain boundary) effects on the permittivity and direct current (d.c.) resistance characteristics of BaTiO₃ ceramics substantially.     

Relationship between Pectic Substances and Strand Separation of Cooked Spaghetti Squash--Part 2. Changes in Firmness,Histological Structure and Pectic Substances during Soaking in Pectin Extractants

The flesh of spaghetti squash separates into strands when cooked. The purpose of this paper is to investigate the cause of strand separation （during cooking） by soaking for 24 h at 35 ℃ in solutions with three kinds of pectin extractant. The changes in strand separation, firmness, histological structure and the pectin of flesh during soaking in 0.01 N HCI solution （pH 2.0）, 0.035 M ammonium oxalate solution （pH 4.0） or 2% sodium hexametaphosphate solution （pH 4.0） were investigated. When flesh was soaked in the HCI solution, the separation into strands and removal of calcium and magnesium were greater than that soaked in other pectin extractants. High methoxyl pectin was extracted by soaking in HC1 solution （pH 2.0） due to removal of polyvalent cations. This result shows that high methoxyl pectin glues strands together in the flesh of spaghetti squash. The shape of the cells which constituted strands was round; on the other hand, that of cells surrounded strands was elongated. When cooked in boiling water or soaked at pH 2.0, the shape of the former cells was maintained, but the latter cells, which contributed to adhesion between strands, broke down. Thus, the flesh separated into strands. When flesh was boiled for 15-30 min, pectin degraded and dissolved in the cooking solution; consequently, the flesh separated into strands and also the middle lamella of cell walls of strands separated. However, pectin remaining in strands maintained their crispness.     

Simultaneous detection of Salmonella spp., Salmonella Typhi and Salmonella Typhimurium in sliced fruits using multiplex PCR

This study aimed to determine the prevalence and quantity of Salmonella spp., Salmonella Typhi and Salmonella Typhimurium in sliced fruits from hawker stalls and hypermarkets in Malaysia. Analysis was carried out using the most probable number (MPN) – multiplex polymerase chain reaction (PCR) method. The prevalence of Salmonella spp., Salmonella Typhi and Salmonella Typhimurium in 210 samples of sliced fruits examined were 23.3%, 7.6% and 3.8%, respectively with estimated quantity varying from 0 to 19 MPN/g. This study urged the authority to look into the biosafety of sliced fruits in Malaysia.     

Nationwide survey on pediatric CT among children of public health and school nurses to examine a possibility for a follow-up study on radiation effects

A nationwide survey was conducted in Japan on paediatric CT among children of public health and school nurses to examine a possibility for a follow-up study on radiation effects. A survey questionnaire was sent out to 3173 public primary and junior high schools and 317 public health centres during October to December in 2009. According to the collected responses, 410 (16.2 %) children received the CT scans and the total number of CT scans was 585. Most of respondents expressed a high interest in radiation health effects and an intent to participate in the epidemiological study that will follow-up the health conditions of children. This study provides information to discuss the feasibility of the epidemiological study on health effects in children who received CT scans.     

斜盘式轴向柱塞泵变转速特性的对比研究

斜盘式轴向柱塞泵的低速工况性能是影响整个伺服电机驱动泵控系统效率的重要因素。通过数学模型分析选择最优化的仿真模型,研究并得出定量柱塞泵在变转速工况下的流量特性,结合数学模型和仿真模型,确定了定量柱塞泵在变转速工况下的性能,得到了不同转速下斜盘式轴向柱塞泵的压力波动和流量特性,为探索伺服电机驱动的斜盘式轴向柱塞泵控系统的性能提供了依据。     

压制压力对粉末冶金黄铜件性能的影响

以雾化预合金黄铜粉末80Cu-20Zn为原料,研究了当压制压力分别为380,480,580,680及780 MPa时,对粉末冶金黄铜件力学性能及显微组织的影响.实验结果表明:随着压制压力的增大,锌的挥发量降低;材料的密度、硬度及延伸率则随压制压力增大而增大;材料的抗拉强度随压制压力的增大先升高后下降,在压制压力680 MPa时抗拉强度达到最大值.在温度870℃下烧结的合金的延伸率比温度860℃下烧结的明显提高,但脱锌量增加,合金表面较粗糙.在压制压力为680MPa、烧结温度为870℃的条件下,试样的主要力学性能达到了日本工业标准JIS Z2550-2000的要求.