Comparative Study of Nano Crystalline Ceria Synthesized by Different Wet-Chemical Methods

Cerium oxide (CeO₂) nanoparticles were synthesized by using sol–gel methods and the Composite Mediated Hydrothermal Method (CMHM). Sol–gel synthesis was done for 0.6 M molarity of the precursor solution of cerium nitrate hexa hydrated [Ce(NO₃)₃?6H₂O] and the hydrothermal synthesis was done at 180 °C for 45 min. X-Ray diffraction (XRD) was used to measure the structural properties of the prepared ceria. Scherrer’s formula was used to calculate the crystallite sizes of average and most intense peak. Temperature dependent (200 °C to 700 °C) dc conductivity was measured and found to be increasing with the increase in measuring temperature. The frequency dependent (20 Hz to 3 MHz) ac conductivity and dielectric properties were measured at different temperatures. The comparison of electric and dielectric properties was studied. Both synthesis techniques were further analyzed by the Raman spectrum at 514 nm excitation laser line for the different bands of cerium oxide and oxygen vacancies.     

不同湿度条件下瓦楞纸箱抗压强度的实验研究

通过实验研究得出了瓦楞纸箱的湿度与抗压强度的关系,即湿度越大,抗压强度损失越严重,所以在运输环境湿度较大的情况下,应采取适当措施来提高瓦楞纸箱的抗压强度,避免因瓦楞纸箱强度随湿度降低后,引起瓦楞内装商品损坏的情况出现。     

Microcracking Behaviour of a TiAl-base Alloy with Different Microstructures during Compression

The microcracking behaviour of TiAl-based alloys with the duplex and fully-lamellar microstrcutures was studied during compression. It was found that the fracture involves propagation of the existing microcracks and development of more new nuclei, instead of being a nucleationcontrolled event. The lamellar interfaces, especially those having an angle of about 0~30℃ to the loading axis, were found to be the favourable nucleation sites. Microcrack nucleation is likely to be initiated by tensile normal stress concentrated on the lamellar interfaces.     

Asymmetry Behaviour between Tension and Compression for Prestrained Materials under Cyclic Loading

The prestrained metals show substantial asymmetry between tension and compression in addition tothe softening under cyclic loading, thus the cyclic creep takes place at a load-control test. The soft-ening reflects the decrease in density of dislocation and total internal stress, and the creep implies theasymmetry in back stress between tension and compression, The mechanical behaviour of the soft-ening is similar for materials with different slip modes, but their features of creep differ significantly.The creep of planar slip Cu-Zn alloy exhibits“explosively”, while that of wavy slip Cu and low car-bon steel occurs continuously and slowly. The explanation of creep behaviour via the internal dislo-cation structure was presented in this paper. According to asymmetw behaviour, it can be concludedthat the internal processes of softehing also strongly depend on the slip mode. In addition, underhigh stress amplitude the opposite asymmetries take place for Cu and Cu-Zn alloy, it indicates thatasymmetric back stresses developed in pretension have been eliminated even though the density andthe configuration of dislocations have not reached equilibrium.     

竞争环境下的港口企业两种定价策略比较研究

通过建立港口的空间Hotelling模型,分析了同一区域内双垄断港口企业采用不同定价策略时的均衡价格、需求量和利润,并且对比了不同定价策略下港口的利润.理论研究结果表明:在服务水平相同时,两个竞争的港口企业采用统一定价策略会获得更多的利润;在服务水平不相同时,两个竞争的港口企业采取何种定价策略与它们的地理位置、内陆运费率、服务水平有关.     

不同压缩比2205双相不锈钢轧制复合板组织及性能对比研究

研究了不同压缩比2205双相不锈钢轧制复合板界面和复层的组织和性能。结果表明,压缩比为4和6的复合板复层均由奥氏体和铁素体组成,奥氏体和铁素体相界呈锯齿状;基层和复层界面处碳钢侧为单一铁素体,不锈钢侧可见一条不连续黑色条带;相比压缩比为4的复合板,压缩比为6的复合板复层铁素体含量更高,奥氏体γ相尺寸更小更长,耐腐蚀性更好,但强度无明显差异;基层和复层界面更平整,结合力更低。     

基于湿度影响的蜂窝纸板静态压缩能量吸收图

基于不同厚跨比蜂窝纸板在不同湿度条件下的静态压缩应力应变曲线,构建含应变速率、蜂窝结构等信息的能量吸收图。结果表明:随厚跨比的增大,蜂窝纸板最佳能量吸收点向右上方偏移,其单位体积吸收能量的能力增强;随着相对湿度的增大,蜂窝纸板最佳能量吸收点向左下方偏移,其单位体积吸收能量的能力减弱。     

不同供应链合同的最优订货策略及适用性比较

针对由一个制造商和一个零售商组成的单一易逝品供应链,在随机库存问题报童模型基础上,推导了回购、收入分享和数量折扣合同下,零售商的最优订货策略、零售商和制造商的期望利润,给出了不同供应链合同的适用条件。通过一个皮衣生产、销售供应链的案例,对不同供应链合同下的最优订货策略、合同适用性及原因进行了分析、比较。为理解不同供应链合同的适用性提供了数理依据和案例解释。     

Compaction Behaviour of Musol, A New Direct Compression Vehicle

The compaction characteristics of Musol, a new autocompressible vehicle derived through chemical modification of mucuna gum was investigated. Avicel PH 101, Zeparox and Encompress were used as reference tablet vehicles. Values of the mean yield stress derived from the analysis of Heckel plots indicate that Musol consolidates principally by plastic deformation, The effect of lubrication and recompression on friability, tensile strength and re-working potential of the tablets prepared with the vehicles were determined. While Avicel PH 101 yielded the strongest tablets, Musol showed the highest re-working potential for lubricated and un-lubricated slugs. On the basis of friability, tensile Values of strength and re-working potential, Musol than the grades of Zeparpx or Encompress performed better used in the study.     

Compaction Behaviour of Musol,A New Direct Compression Vehicle

Abstract

The compaction characteristics of Musol, a new autocompressible vehicle derived through chemical modification of mucuna gum was investigated. Avicel PH 101, Zeparox and Encompress were used as reference tablet vehicles. Values of the mean yield stress derived from the analysis of Heckel plots indicate that Musol consolidates principally by plastic deformation, The effect of lubrication and recompression on friability, tensile strength and re-working potential of the tablets prepared with the vehicles were determined. While Avicel PH 101 yielded the strongest tablets, Musol showed the highest re-working potential for lubricated and un-lubricated slugs. On the basis of friability, tensile Values of strength and re-working potential, Musol than the grades of Zeparpx or Encompress performed better used in the study.     

Spray-Dried Rice Starch: Comparative Evaluation of Direct Compression Fillers

Spray-dried rice starch (SDRS), microcrystalline cellulose (MCC), lactose (L), pregelatinized starch (PS), and dibasic calcium phosphate (DCP) were studied for their flow behaviors and tableting properties. Both flow rate and percent compressibility values indicated that SDRS exhibited excellent flowability. The increase in magnesium stearate content reduced the hardness of MCC and SDRS tablets; however, general tablet properties were still acceptable while the PS tablets were unsatisfactory at high lubricant concentrations. The hardness of L or DCP tablets was not affected by the lubricant. The disintegration of L tablets was prolonged with the increased lubricant concentration while that of PS tablets seemed to be decreased due to softened tablets. The disintegration times of MCC and SDRS tablets seemed to be independent of the lubricant added. With respect to the dissolution, SDRS-based tablets offered fast and complete release of the drug regardless of its solubility. SDRS, L, and DCP exhibited comparable carrying capacity for ascorbic acid. The best dilution potential was obtained with MCC while the worst was obtained with PS.     

Spray-Dried Rice Starch: Comparative Evaluation of Direct Compression Fillers

Abstract

Spray-dried rice starch (SDRS), microcrystalline cellulose (MCC), lactose (L), pregelatinized starch (PS), and dibasic calcium phosphate (DCP) were studied for their flow behaviors and tableting properties. Both flow rate and percent compressibility values indicated that SDRS exhibited excellent flowability. The increase in magnesium stearate content reduced the hardness of MCC and SDRS tablets; however, general tablet properties were still acceptable while the PS tablets were unsatisfactory at high lubricant concentrations. The hardness of L or DCP tablets was not affected by the lubricant. The disintegration of L tablets was prolonged with the increased lubricant concentration while that of PS tablets seemed to be decreased due to softened tablets. The disintegration times of MCC and SDRS tablets seemed to be independent of the lubricant added. With respect to the dissolution, SDRS-based tablets offered fast and complete release of the drug regardless of its solubility. SDRS, L, and DCP exhibited comparable carrying capacity for ascorbic acid. The best dilution potential was obtained with MCC while the worst was obtained with PS.     

Computer Determination and Comparison of the Compression Behaviour of Powder Mixtures

The aim of this work is to analyse the forces measured and stored during compression by using a computer.

We propose to calculate a “tabletibility index” which is very useful to classify the materials according to their capacity to give proper tablets by direct compression. We can also simulate the energy cycles in chosen experimental conditions, as it is not possible to compare cycles if the experimental conditions are not the same, which is very difficult to obtain.

In addition, this program calculates a “cohesion index” which is a dimensionless number. With this program and this cohesion index, it is possible to define the behaviour of different powder mixtures during compression very accurately. This is very useful to compare a batch to a reference as far as quality control, process control and formulation are concerned.     

不同光源下样品颜色三刺激值测试的比较分析

针对光学伪装勘察和检测的特殊性,在380～800nm波长范围里,比较了不同颜色样品分别在太阳光和D65光源下三刺激值的差别,采用CIE1976L*a*b*空间分析了2种光源下颜色样品的色差。结果表明,太阳光作为光学伪装勘察和检测的标准光源更加客观、准确。     

金属丝网与金属橡胶材料的压缩特性对比研究

通过分析金属丝网垫和金属橡胶垫的制备工艺、细观特征并对其进行静态压缩试验,研究压缩变形量和密度对金属丝网垫和金属橡胶垫材料压缩力学性能的影响,从而分析这两种材料的承载能力和能量耗散特性。试验结果表明：金属丝网垫和金属橡胶垫材料的载荷-位移曲线具有相同的变化趋势且都具有刚度非线性特性;但是在相同的尺寸和密度下,金属橡胶垫的承载能力较金属丝网垫的承载能力强,且在相同的变形条件下金属橡胶的能量耗散能力较金属丝网垫的能量耗散能力强,即金属橡胶的阻     

Comparative Evaluation of Several Direct Compression Sugars

Three new and two commercially available sugar matrices were comparatively evaluated for several fundamental properties of direct compression powder systems. These properties included: particle size distribution, powder flow (determined by a recording powder flow meter), bulk density and moisture content. The matrices studied were Dipac, Nutab, and California and Hawaiian (C & H) Products A, B, and C. These matrices were formulated in to chewable ascorbic acid, multivitamin, and antacid tablets, and analyzed for: weight uniformity, thickness, diameter, hardness, disintegration, resistance to impact stress, friability, dissolution and effect due to aging.

The data obtained showed that the new products (C & H products) were comparable, and in some cases, even superior to the commercially available ones.     

Comparative Evaluation of Direct Compression Ampicillin Formulations

Direct compression formulations were developed for ampicillin using methyl vinyl ether/maleic anhydride copolymer (I) and vinyl acetate/crotonic acid copolymer (II) as binders. A comparison was made between these formulations and wet granulation method using gelatin as binder regarding the chemical stability of ampicillin as a function of relative humidity (55 to 90%) and temperature (40 to 75°C). Polymer I showed least moisture uptake followed by polymer II and gelatin. The mechanism suggested here involves moisture uptake and dissolution followed by chemical decomposition. The temperature had lesser effect on stability because of low activation energies but an Arrhenius relationship was established for three formulations studied. It was concluded that formulation using polymer I gives the most ideal combination of physiochemical properties for the direct compression of ampicillin in solid dosage forms.     

Comparative Evaluation of Several Direct Compression Sugars

Abstract

Three new and two commercially available sugar matrices were comparatively evaluated for several fundamental properties of direct compression powder systems. These properties included: particle size distribution, powder flow (determined by a recording powder flow meter), bulk density and moisture content. The matrices studied were Dipac, Nutab, and California and Hawaiian (C & H) Products A, B, and C. These matrices were formulated in to chewable ascorbic acid, multivitamin, and antacid tablets, and analyzed for: weight uniformity, thickness, diameter, hardness, disintegration, resistance to impact stress, friability, dissolution and effect due to aging.

The data obtained showed that the new products (C & H products) were comparable, and in some cases, even superior to the commercially available ones.     

FRP confined concrete columns: Behaviour under extreme conditions

The behaviour of concrete columns wrapped with fibre reinforced polymer (FRP) materials when exposed to several extreme conditions is evaluated. Cold regions environments, FRP repair of corroding reinforced concrete columns, and fire resistance are all considered. For the cold regions exposure, FRP wrapped cylinders (152 × 305 mm) are exposed to temperatures as low as −40 °C or to up to 300 cycles of freeze-thaw (−18 °C to +15 °C). The combination of freeze-thaw exposure with sustained loading is also examined. For FRP wrapping of corroding reinforced concrete columns, the results of tests on cylinders and larger-scale circular columns (300 × 1200 mm) are presented. The specimens are corroded and then wrapped with FRP sheets. The rate of corrosion is monitored both before and after wrapping. The final extreme condition that is considered is fire exposure. Tests on full-scale reinforced concrete columns (400 × 3800 mm) exposed to a standard fire are described and discussed. Overall, the results demonstrate that FRP confined concrete columns tested in concentric axial compression have adequate performance under several extreme conditions such as low temperature, freeze-thaw action, corrosion of internal reinforcement, and fire exposure.     

Comparative Study of TiAu-Based TES Microcalorimeters with Different Geometries

Seven microcalorimeters with different geometries have been tested and their performance is compared. The study, for TiAu TESs with a Cu absorber, indicates the presence of so-called constant voltage noise and internal thermal fluctuation noise. The constant voltage noise is not changed by a normal metal pattern on the TES, or by a magnetic field. The energy resolution of the detectors, having different heat capacities, is 2.5 and 5.0 eV (at 5.9 keV).