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31.
Menglu Yang Nora Botten Robin Hodges Jeffrey Bair Tor P. Utheim Charles N. Serhan Darlene A. Dartt 《International journal of molecular sciences》2022,23(1)
Resolvin (Rv) D2 and RvD1 are biosynthesized from docosahexaenoic acid (DHA) and promote resolution of inflammation in multiple organs and tissues, including the conjunctiva. Histamine is a mediator produced by mast cells in the conjunctiva during the allergic response. We determined the interaction of RvD2 with histamine and its receptor subtypes in cultured conjunctival goblet cells and compared them with RvD1 by measuring intracellular [Ca2+] and mucous secretion. Treatment with RvD2 significantly blocked the histamine-induced [Ca2+]i increase as well as secretion. RvD2 and RvD1 counter-regulate different histamine receptor subtypes. RvD2 inhibited the increase in [Ca2+]i induced by the activation of H1, H3, or H4 receptors, whereas RvD1 inhibited H1 and H3 receptors. RvD2 and RvD1 also activate distinct receptor-specific protein kinases to counter-regulate the histamine receptors, probably by phosphorylation. Thus, our data suggest that the counter-regulation of H receptor subtypes by RvD2 and RvD1 to inhibit mucin secretion are separately regulated. 相似文献
32.
Reactions between Strontium-Substituted Lanthanum Manganite and Yttria-Stabilized Zirconia: II, Diffusion Couples 总被引:1,自引:0,他引:1
Kjersti Kleveland Mari-Ann Einarsrud Christian R. Schmidt Senem Shamsili Sonia Faaland Kjell Wiik Tor Grande 《Journal of the American Ceramic Society》1999,82(3):729-734
Formation of secondary phases and diffusion of cations in diffusion couples of yttria-stabilized zirconia and lanthanum manganite substituted with 0 to 60 mol% strontium have been studied by scanning electron microscopy and energy dispersive X-ray spectroscopy. Only the primary phases were observed after 120 h at 1200°C, while formation of secondary phases was identified already after 1 h heat treatment at 1350°C. The phase composition of the reaction layer altered from La2 Zr2 O7 to SrZrO3 at increasing Sr content in La x Sr1- x MnO3 . The thickness of the reaction layer was increasing with heat treatment time. In diffusion couples of La0.4 Sr0.6 MnO3 formation of manganese oxide was observed in the perovskite layer after 1 h heat treatment at 1350°C, while isolated grains of SrZrO3 relatively deep inside the zirconia were observed after longer heat treatment time. Diffusion of Mn into zirconia was observed preferenced along grain boundaries in the early stage of the interface reaction. 相似文献
33.
The behavior of different acid zeolites in the hydrolysis at room temperature of methyl tert-butyl ether (MTBE) was studied with reference to the possibility of its conversion to more biodegradable products in underground water contaminated by MTBE. The effect of the structure of the zeolite and SiO2/Al2O3 ratio was analyzed. The results indicate that acid H-MFI and H-BEA zeolites are effective in both adsorption and hydrolysis of MTBE and may be applied for both in situ underground water remediation and as protection barrier for wells or leaking tanks. However, other zeolites (mordenite and faujasite) result completely inactive. Furthermore, contrary to what was expected, the increase of the Si/Al ratio promotes the reactivity which is determined by the resistance to diffusion of MTBE in the pores of zeolites and the resistance of back-diffusion of the reaction products. 相似文献
34.
Current Trends in Pretreatment and Fractionation of Lignocellulose as Reflected in Industrial Patent Activities 下载免费PDF全文
The pretreatment process to disintegrate lignocellulose and to fractionate its three main components hemicellulose, cellulose, and lignin, is a crucial step to enable sustainable and economic value chains based on biomass feedstock. This review provides an overview of the recent patenting activities on pretreatment. Most of these activities focus on optimization of different known processes to improve economics, such as increased catalyst efficiency, effluents recirculation, or lignin valorization. However, also a number of patents and demonstration activities based on emerging concepts for pretreatments are observed. 相似文献
35.
Barry Haseltine Tor‐Ulf Weck Lars Meyer Rob van der Pluijm Oliver Dupont Christoph Alfes Wolfram Jaeger John Roberts Jonathan Silver Dirk Martens O. Pfeffermann Bastian Drewes Erhard Gunkler Jan Kubica Nebojsa Mojsilovic Erhard Gunkler Johann Marx Armin Ohler Hipolito Sousa Rui Sousa Romeu S. Vicente J. R. Mendes Silva Roberto Capozucca 《Mauerwerk》2011,15(6):348-361
36.
This paper reports preliminary work to investigate the suitability of using a blackboard framework as a problem-solving model for stamping process planning in progressive die design. The model is described at two levels: knowledge level and computational level. The knowledge level describes how the stamping process planning domain is represented in a blackboard architecture. The computational level describes how the blackboard architecture is modeled and implemented using object technology. A software prototype has been developed using CLIPS and C++ interfaced with Solid Edge CAD system. An example is presented to illustrate the feasibility and practicality of the proposed approach. 相似文献
37.
Shifts in biodegradation kinetics of the herbicides MCPP and 2,4-D at low concentrations in aerobic aquifer materials 总被引:1,自引:0,他引:1
Biodegradation kinetics of two phenoxy acid herbicides, MCPP [(+/-)-2-(4-chloro-2-methylphenoxy)propanoic acid; mecoprop] and 2,4-D [2,4-dichlorophenoxyacetic acid] were studied in laboratory batch microcosms at low concentrations (0.025-100 microg/L) using 14C technique with sediments and groundwater from a shallow aerobic sandy aquifer. Below a certain threshold concentration of approximately 1 microg/L for 2,4-D and 10 microg/L for MCPP, the biodegradation followed first-order nongrowth kinetics, and no adaptation was observed within the experimental period of 341 d. Half-lifes for ultimate degradation were 500 d for 2,4-D and 1100 d for MCPP at 10 degrees C in unpolluted aquifer sediment in this environmentally relevant concentration regime. Above the threshold concentrations, the biodegradation rate accelerated gradually due to selective growth of specific biomass, which was ascertained from 14C most probable number enumerations of specific phenoxy acid degraders. Atthe highest concentration tested (100 microg/ L), specific degraders increased from 10(-1) to 10(5) cells/g during the experiment, and half-lifes after adaptation decreased to approximately 5 d. The enhanced rate of degradation by adapted systems was maintained during degradation of the last residuals measured to less than 0.1 microg/L. In situ long-term preexposure of the aquifer sediment also resulted in significant higher degradation rates of the phenoxy acids. 相似文献
38.
Monica Finsrud Mats E. Høvin Tor S. Lande 《Analog Integrated Circuits and Signal Processing》2003,36(1-2):21-29
MASH delta-sigma () modulators consist of a cascade of several lower order single-loop modulators. In an ideal cascade, the quantization error from all but the last stage are digitally canceled. The drawback with a cascaded design is the requirement of precise matching of contributions from different quantizers to cancel lower order quantization noise from intermediate delta-sigma stages. This paper presents a new, adaptive improvement to the residue coupled MASH delta sigma modulator. The adaptive corrections significantly reduce the sensitivity to analog imperfections. The result is a simple MASH delta-sigma modulator with high precision. Simulations of a 1-1 MASH circuit structure with errors and corrections are included to confirm the theory. 相似文献
39.
40.
In an additive-manufactured metallic part, distinct and different microstructure and mechanical properties may exist in different areas due to differences in shape and location. Two parts, one with straight-finned structure and the other with curve-finned structure, were fabricated by the selective electron beam melting method using pre-alloyed Ti–6Al–4V ELI powder. Microstructural characterisation of these two parts that have varying fin thickness and shape was carried out to investigate the synthetical influence of 2D planar build geometry and in-fill hatching strategy on selective electron beam melting. It was found that the β interspacing is larger in the curve-finned structure, leading to a lower microhardness as compared to the straight-finned structure. It suggests a slower cooling rate in the curve-finned structure due to the differences in build geometry and in-fill hatching strategy. 相似文献