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  • Author or Editor: D. Feng x
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Abstract  

We prove the following theorem. Assume fL (R 2) with bounded support. If f is continuous at some point (x 1,x 2) ∈ R 2, then the double Fourier integral of f is strongly q-Cesro summable at (x 1,x 2) to the function value f(x 1,x 2) for every 0 < q < ∞. Furthermore, if f is continuous on some open subset

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of R 2, then the strong q-Cesro summability of the double Fourier integral of f is locally uniform on
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.

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Abstract  

KDNBF (potassium 4,6-dinitrobenzofuroxan) has been used as a primer explosive in igniters and detonators for many years. Considerable information about the sensitivity of KDNBF to various stimuli, such as impact, friction, shock and electrostatic charge, is known. However, the thermal sensitivity of KDNBF has been relatively unexplored. Hence, there is very little information available concerning the fundamental thermal properties of KDNBF. Therefore, as part of an extensive thermal hazard assessment, DSC, TG, accelerating rate calorimetry (ARC) and heat flux calorimetry (HFC) measurements have been undertaken on KDNBF. The results demonstrate that KDNBF decomposes via a multi-step exothermic process directly from the solid state. The decomposition process does not appear to depend on the nature of the atmosphere, except in the final stage of the TG decomposition in air, where remaining carbonaceous material is converted to CO2. The first stage of the decomposition is sufficiently rapid that ignition occurs if too large a sample is used. Dynamic and isothermal methods were used to obtain the kinetic parameters and a range of activation energies were obtained, depending on the experimental conditions. The kinetic results have been analyzed in terms of various solid state decomposition models.

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Abstract  

DSC measurements have been used to investigate the thermal stability of each of four specific detection agents, prescribed by the International Civil Aviation Organization for incorporation into explosives at the point of manufacture. Additionally, the compatibility of these agents with a number of commercial explosives has been assessed. DSC results for a complete study of mixtures of the agents with the explosive, tetryl are specifically described. The thermograms are compared with those of the pure agents and tetryl, the thermal decomposition of which has been previously characterized.

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Abstract  

Yaozhou Kiln at Lidipo and Shangdian are two independent porcelain kiln groups of Yaozhou kiln series in Shanxi Province. Both of them were consisted of some individual porcelain kilns. The samples of 20 pieces of porcelain sherds produced in Shangdian and 43 pieces of porcelain sherds made in Lidipo sites which produced in Kin Dynasty (1115–1234 A.D.) have been collected. The main chemical compositions in body were determined by X-ray fluorescence (XRF). The contents of trace elements were measured using neutron activation analysis (NAA). Principal component analysis (PCA) and stepwise discriminant analysis were used to study the provenance characteristic of these samples. The results indicated that the main components and trace elements in the specimen can be used to reveal the provenance characteristic.

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Cytomixis has been described in many plant species, but not in Thinopyrum . The present study reports spontaneous cytomixis during microsporogenesis in Thinopyrum intermedium (2n = 42), Thinopyrum ponticum (2n = 70), and their F 1 hybrids with wheat. Cytomixis frequently occurred in early prophase I but very rarely in meiosis II. The type of cytomixis that occurred most often was where chromatins migrate from one nucleus into an adjacent cel1. Migration from one nucleus into two or more cells or from two or more nuclei into one cel1 was also observed. After a donor cell transferred chromatin to a recipient cell, the recipient cell would sometimes pass the chromatin on to another cell. Migration did not necessarily occur between cells in the same stage. Cytomixis in Th. ponticum and its hybrids with wheat was more complex than that in Th. intermedium . The possible causes, cytological consequences and genetic significance of cytomixis are discussed.

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Abstract  

A Tian-Calvet heat flux calorimeter has been modified for use with high pressures in measurements of thermal hazards of materials. The system comprising a specially designed high pressure vessel and an associated manifold is described. With this system, comparative measurements using both standard and high pressure vessels can be made, different materials and/or liners can be used for the high pressure vessel and an assessment of the influence of the gaseous environment on thermal behaviour can be made. Calibration was carried out in the range 25 to 300C at different pressures and heating rates, using sapphire and the calibration results were verified with benzoic acid, both reference grade materials. With the new vessel, pressures up to about 70 MPa can be used or recorded during the thermal decomposition of energetic materials. The reproducibility of the baseline, as illustrated by standard error results, was about 0.02% compared with 0.13% for the standard vessel, over the entire temperature range. The corresponding results for the baseline of the pressure vessel at 5.5 MPa (in air and Ar) and in a calibration experiment with sapphire were 0.08%. Experimental data obtained for ammonium nitrate and 2,3-dimethyl-2,3-dinitrobutane in the standard and pressure vessels are compared and discussed. The effect of pressure and the nature of the gaseous environment (inert or oxidizing) on the results for these two materials will be described.

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Abstract  

Isopropylnitrate (IPN) is described as a detonable material used in propellants and explosives. While there is considerable information available on its sensitivity and compatibility with other materials, very little is known about its thermochemical properties. This paper will describe the results obtained from some DSC, heat flux calorimetry (HFC) and accelerating rate calorimetry (ARC) measurements. The ASTM DSC method using a hermetic aluminum pan having a lid with a laser-produced pin hole was used to determine the vapour pressure of IPN1. Results calculated from an Antoine equation are in substantial agreement with those determined from DSC measurements. From the latter measurements, the enthalpy of vaporization was determined to be 35.320.62 kJ mol−1. Attempts to determine vapour pressures above about 0.8 MPa resulted in significant decomposition of IPNg. The enthalpy change for decomposition in sealed glass systems was found to be -3.430.09 kJ g−1 and -3.850.03 kJ g−1, respectively from DSC and HFC measurements on IPN1 samples loaded in air. Slightly larger exotherms were observed for the HFC results in air than those in inert gas, suggesting some oxidation occurs. In contrast, no significant difference in the observed onset temperature of about 150C was observed for both the HFC and ARC results. From DSC measurements, an Arrhenius activation energy for decomposition of 1264 kJ mol−1 was found. These measurements were also conducted in sealed glass systems and decomposition appeared to proceed primarily from the liquid phase.

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Summary  

PM10 and PM2.5 samples were collected simultaneously in Beijing, China, and analyzed by INAA and ICP-MS. Seasonal variations of the concentrations of ambient particles and their elemental compositions were found. The main sources of PM10 and PM2.5 in spring were the crust, coal burning and vehicle exhaust, in which the former was significant. During a strong dust storm, the concentrations of the crustal elements in PM10 and PM2.5 increased remarkably, but the concentrations of some anthropogenic elements decreased. The enrichment factors of these anthropogenic elements also decreased sharply during the dust storm, which indicated that they were mostly originated from local anthropogenic pollution and diluted by the huge amount of dust.

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Analysis of the binding interaction of (−)-epigallocatechin-3-gallate (EGCG) and pepsin is important for understanding the inhibition of digestive enzymes by tea polyphenols. We studied the binding of EGCG to pepsin using fluorescence spectroscopy, Fourier transform infrared spectroscopy, isothermal titration calorimetry, and protein-ligand docking. We found that EGCG could inhibit pepsin activity. According to thermodynamic parameters, a negative ΔG indicated that the interaction between EGCG and pepsin was spontaneous, and the electrostatic force accompanied by hydrophobic binding forces may play major role in the binding. Data from multi-spectroscopy and docking studies suggest that EGCG could bind pepsin with a change in the native conformation of pepsin. Our results provide further understanding of the nature of the binding interactions between catechins and digestive enzymes.

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Abstract  

The effects of two Chinese prescriptions, Zhugu and Shengu capsules were studied on calcium absorption. The absorption ratios of Zhugu and Shengu was 30.4% and 21.5%, respectively.

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