A new interpolation method based on satellite physical character in using IGS precise ephemeris

Due to the deficiency of sliding Lagrange polynomial interpolation, the author proposes a new interpolation method, which considers the physical character of satellite movement in coordinate transformation and reasonable selection of interpolation function. Precision of the two methods is compared by a numerical example. The result shows that the new method is superior to the sliding Lagrange polynomial interpolation in interpolation and extrapolation, especially in extrapolation that is over short time spans.

Single Crystal Growth and Physical Property Characterization of Non-centrosymmetric Superconductor PbTaSe_2

We report on the single crystal growth and superconducting properties of PbTaSe2 with the non-centrosymmetric crystal structure. By using the chemicM vapor transport technique, centimeter-size single crystals are success- fully obtained. The measurement of temperature dependence of electricaJ resistivity p（T） in both normal and superconducting states indicates a quasi-two-dimensional electronic state in contrast to that of polycrystalline samples. Specific heat C（T） measurement reveals a bulk superconductivity with Tc ≈ 3.75K and a specific heat jump ratio of 1.42. All these results are in agreement with a moderately electron-phonon coupled, type-g Bardeen-Cooper-Schrieffer superconductor.

Impact of open dumping of municipal solid waste on soil properties in mountainous region

This paper presents the effect of open dumping of municipal solid waste(MSW) on soil characteristics in the mountainous region of Himachal Pradesh, India. The solid waste of dumpsite contains various complex characteristics with organic fractions of the highest proportions. As leachate percolates into the soil, it migrates contaminants into the soil and affects soil stability and strength. The study includes the geotechnical investigation of dump soil characteristics and its comparison with the natural soil samples taken from outside the proximity of dumpsites. The geochemical analysis of dumpsite soil samples was also carried out by scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS).Visual inspection revealed that the MSW consists of high fraction of organics, followed by paper. The soil samples were collected from five trial pits in the dumpsites at depths of 0.5 m, 1 m and 1.5 m. Then the collected soil samples were subjected to specific gravity test, grain size analysis, Atterberg’s limit test,compaction test, direct shear test, California bearing ratio(CBR) test and permeability analysis. The study indicated that the dumpsite soils from four study regions show decreasing trends in the values of maximum dry density(MDD), specific gravity, cohesion and CBR, and increasing permeability as compared to the natural soil. The results show that the geotechnical properties of the soils at all four study locations have been severely hampered due to contamination induced by open dumping of waste.

Elaboration and Characterization of Composite Materials Reinforced by Papaya Trunk Fibers (<i>Carica papaya</i>) and Particles of the Hulls of the Kernels of the Winged Fruits (<i>Canarium schweinfurthii</i>) with Polyester Matrix

In this work we determine the physical and mechanical properties of local composites reinforced with papaya trunk fibers (FTP) on one hand and particles of the hulls of the kernels of the garlic (PCNFA) in the other hand. The samples are produced according to BSI 2782 standards;by combining fibers and untreated to polyester matrix following the contact molding method. We notice that the long fibers of papaya trunks improve the tensile/compression characteristics of composites by 45.44% compared to pure polyester;while the short fibers improve the flexural strength of composites by 62.30% compared to pure polyester. Furthermore, adding fibers decreases the density of the final composite material and the rate of water absorption increases with the size of the fibers. As regards composite materials with particle reinforcement from the cores of the winged fruits, the particle size (fine ≤ 800 μm and large ≤ 1.6 mm) has no influence on the Young’s modulus and on the rate of water absorption. On the other hand, fine particles improve the flexural strength of composite materials by 53.08% compared to pure polyester;fine particles increase the density by 19% compared to the density of pure polyester.

Sintering effects on chemical and physical properties of bioactive ceramics

The objective of this study was to characterize the chemical and physical properties of bioactive ceramics prepared from an aqueous paste containing hydroxyapatite(HA)and beta tri-calcium phosphate(β-TCP).Prior to formulating the paste,HA andβ-TCP were calcined at 800℃and 975℃(11 h),milled,and blended into 15%/85%HA/β-TCP volume-mixed paste.Fabricated cylindrical rods were subsequently sintered to 900℃,1100℃or 1250℃.The sintered specimens were characterized by helium pycnometry,X-ray diffraction(XRD),Fourier transform-infrared(FT-IR),and inductively coupled plasma(ICP)spectroscopy for evaluation of porosity,crystalline phase,functional-groups,and Ca:P ratio,respectively.Mechanical properties were assessed via 3-point bending and diametral compression.Qualitative microstructural evaluation using scanning electron microscopy(SEM)showed larger pores and a broader pore size distribution(PSD)for materials sintered at 900℃and 1100℃,whereas the 1250℃samples showed more uniform PSD.Porosity quantification showed significantly higher porosity for materials sintered to 900℃and 1250℃(p<0.05).XRD indicated substantial deviations from the 15%/85%HA/β-TCP formulation following sintering where lower amounts of HA were observed when sintering temperature was increased.Mechanical testing demonstrated significant differences between calcination temperatures and different sintering regimes(p<0.05).Variation in chemical composition and mechanical properties of bioactive ceramics were direct consequences of calcination and sintering.

Fe-N-C电催化氧还原反应催化剂的研究进展

氧还原反应(ORR)是燃料电池和金属-空气电池等各种能源转换器件中重要的半反应.由于ORR的动力学缓慢,需要开发高活性电催化剂来替代常用的贵金属铂基催化剂.Fe-N-C催化剂被认为是最有前景的材料,其丰富的活性位点可以降低含氧中间体的能垒.在这篇综述中,我们详细总结了Fe-N-C催化剂在理论和实验研究方面的最新研究进展.首先,概述了基于Fe-N-C催化剂的电催化ORR的反应机理.然后,对Fe-N-C催化剂的设计策略和活性位点进行了分类.接下来,讨论了活性位点与催化性能之间的关系.介绍了Fe-N-C催化剂在燃料电池和锌空气电池中的应用现状.最后,进一步提出了Fe-N-C催化剂在可控合成、机理研究和能源器件应用方面面临的挑战和机遇.

Determination of microcapsule physicochemical, structural, and mechanical properties

Research into the fundamental properties of microcapsules and use of the results to develop a wide variety of products in industries such as printing, fast-moving consumer goods, construction, pharmaceuticals, and agrochemicals is a dynamic and ever-progressing field of study. For microcapsules to be effective in providing protection from harsh environments or delivering large payloads, it is essential to have a good understanding of their properties to enable quality control during formulation, storage, and applications. This review aims to outline the commonly used techniques for determining the physicochemical, struc- tural, and mechanical properties of microcapsules, and highlights the interlinked nature of these three areas with respect to the end-use industrial application. This review provides information on techniques that are well supported in the literature, and also examines microcapsule analytical techniques that will become more prevalent as a result of new technological developments or extensions from other areas of study.

Comprehensive Evaluation of Powdered Chinese Herbal Medicines-An Exemplification of Isatidis Radix

Objective Currently, powdered Chinese herbal medicines （CHMs） were mainly evaluated through physical property, chemical dissolution, and bioactivity independently. It could not reflect the quality comprehensively. This paper was to explore and establish a comprehensive evaluation method for powdered CHMs. Methods Isatidis Radixwas chosen as an exemple. Firstly, powdered Isatidis Radixin different particle size was prepared. Then, their physical properties were characterized. The dissolution of index component epigoitrin was determined, and their antiviral activities were evaluated by neuraminidase-based bioassay. Results As the particle size decreased, powder distribution tended to be uniform, and the dissolution of epigoitrin increased, antiviral activity enhanced. According to cluster analysis of above results, the sequence of evaluation consequence was ultrafine powder S2 （D90：32.80± 0.29） 〉 ultrafine powder S1 （D90：52.08 ± 0.53） 〉 fine powder SO （D90：118.16± 0.76） （from the superior to the inferior）. Conclusion Overall, the comprehensive evaluation for powdered CHMs based on the physical characterization, chemical dissolution, and bioassay could not only be used to evaluate powdered herbs, but also guide the screening and optimization of the particle size of powder.