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41.
Jingtang Ma 《Journal of Mathematical Analysis and Applications》2009,356(2):674-688
In this paper we analyze the numerical solution of Volterra integro-differential equations of neutral type with weakly singular kernels. We establish a priori error estimations for the finite-element-method semi-discretization of the given problem by defining a suitable Ritz-Volterra projection operator: here, the key point in the proof is the fact that the definition of the Ritz-Volterra projection operator that is not related to the neutral term. We then discuss the discontinuous Galerkin time-stepping method for the semi-discretized equation, together with a fully discretized form. 相似文献
42.
Yang Zhou Chunguo Qian Depo Yang Cailin Tang Xinjun Xu E-Hu Liu Jingtang Zhong Longping Zhu Zhimin Zhao 《Molecules (Basel, Switzerland)》2021,26(9)
Amomum Villosum Lour. (A. villosum) is a folk medicine that has been used for more than 1300 years. However, study of the polysaccharides of A. villosum is seriously neglected. The objectives of this study are to explore the structural characteristics of polysaccharides from A. villosum (AVPs) and their effects on immune cells. In this study, the acidic polysaccharides (AVPG-1 and AVPG-2) were isolated from AVPs and purified via anion exchange and gel filtration chromatography. The structural characteristics of the polysaccharides were characterized by methylation, HPSEC-MALLS-RID, HPLC, FT-IR, SEM, GC-MS and NMR techniques. AVPG-1 with a molecular weight of 514 kDa had the backbone of → 4)-α-d-Glcp-(1 → 3,4)-β-d-Glcp-(1 → 4)-α-d-Glcp-(1 →. AVPG-2 with a higher molecular weight (14800 kDa) comprised a backbone of → 4)-α-d-Glcp-(1 → 3,6)-β-d-Galp-(1 → 4)-α-d-Glcp-(1 →. RAW 264.7 cells were used to investigate the potential effect of AVPG-1 and AVPG-2 on macrophages, and lipopolysaccharide (LPS) was used as a positive control. The results from bioassays showed that AVPG-2 exhibited stronger immunomodulatory activity than AVPG-1. AVPG-2 significantly induced nitric oxide (NO) production as well as the release of interleukin (IL)-6 and tumor necrosis factor alpha (TNF-α), and upregulated phagocytic capacities of RAW 264.7 cells. Real-time PCR analysis revealed that AVPG-2 was able to turn the polarization of macrophages to the M1 direction. These results suggested that AVPs could be explored as potential immunomodulatory agents of the functional foods or complementary medicine. 相似文献
43.
粘胶纤维毡由化学药品LA催化预处理,然后经高温820~850℃下水蒸汽活化来制备粘胶活性炭纤维,其孔结构受热解炭化和活化过程的影响。本文研究了不同升温速率、不同温度下通入水蒸汽以及不同空速对活化结果的影响;同时考察了粘胶炭纤维与水蒸汽反应的动力学以及粘胶活性炭纤维的吸附性能。 相似文献
44.
Sandwich holographic interferometry was first proposed by Prof. N. Abramson in 1974. There are many advantages in using this method. One of its most important virtues is that it can compensate for rigid body displacements between the two exposures and is very convenient in practical operation. The authors have already made a detailed theoretical analysis of in-plane and out-of-plane displacements. This paper describes experimental measurements of the residual stresses in welds, by studying the curvature or the second-order derivative of the fringes of in-plane or out-of-plane displacements, using sandwich holographic interferometry. The stresses are obtained quantitatively, and are verified by an experiment involving measurements of the stresses of a flat plate. 相似文献
45.
Catalytic ozonation of phenolic wastewater with activated carbon fiber in a fluid bed reactor 总被引:2,自引:0,他引:2
The effect of activated carbon fiber (ACF) on the ozonation of phenol in water in a fluid bed reactor was investigated. It was observed that this combined process could increase the yield of the oxidation process significantly for phenol and COD (chemical oxygen demand) removal, especially for the phenol removal. The efficiency of ozonation increased with an increase in the dose of ACF. Higher initial phenol concentration only caused a slight decrease of phenol and COD removal. The results of repeated use found that ozonation could efficiently regenerate ACF in situ in the reactor, which was considered easy to handle without the costly ex situ regeneration of the industrial treatment process. The Boehm titrations and FTIR studies indicate that the ozonation process in water can significantly change the composition of acidic surface oxygen-containing groups of ACF, leading to the increase of carboxylic, hydroxylic, and carbonylic groups and the slight decrease of the lactonic groups. Furthermore, this process can also increase the surface area and total pore volume of ACF. Due to the new micropore formation and some pore enlargement, the micropores became smaller, and the mesopores and macropores got bigger. 相似文献
46.
Two transiton metal phosphonates, Cd2[OOCC5H3NPO3H]2·H2O (1) and Zn[OOCC5H4NPO3]·H2O (2), were synthesized by hydrothermal reactions. Single-crystal X-ray diffraction analyses show that both have a 3-D framework. In 1, the asymmetric [Cd–NO5] octahedron is connected to the [P–CO3] tetrahedron through corner sharing and two neighboring [Cd–NO5] octahedra are bridged via a mutual plane [O1–O2–O3]. Compound 2 has a scales-like multilayer structure viewing from b and c. [Zn–O4] tetrahedra linked [P–CO3] tetrahedra through corner O sharing. The thermogravimetric properties and luminescence spectra of 1 and 2 were investigated. Compound 2 emitted a purple-blue light upon 323 nm excitation. Above 100 nm, red shifts in both compounds make them candidates for luminescent materials. 相似文献
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49.
Preparation of mesoporous carbon from commercial activated carbon with steam activation in the presence of cerium oxide 总被引:2,自引:0,他引:2
Mesoporous carbon was prepared from the commercial activated carbon by steam activation with cerium oxide as catalyst. Steam activation with a catalyst loading of 0.5-2.0 wt% at 680-870 degrees C was examined. The surface area and pore size were evaluated by nitrogen adsorption at 77 K, and the structure of cerium oxide was characterized by XRD, XPS, and TEM. The results showed that the catalyst promoted the development of a mesopore at lower temperature (680-740 degrees C), and the mesopore was concentrated around 4-10 nm. The noncatalytic activation was advantageous in mesopore development and the catalyst would restrict the formation of mesopores at high temperature (800-870 degrees C). Higher loading of cerium oxide and higher activation temperature caused the aggregation of cerium oxide and then resulted in scattered pore size distribution. 相似文献
50.