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41.
Protein tyrosine nitration is a post-translational modification that occurs under conditions of oxidative stress and may play a role in the pathogenesis of diseases such as asthma. Through their ability to generate reactive oxygen species in macrophages and epithelial cells, particulate pollutants, such as diesel exhaust particles (DEPs), may lead to a worsening of the asthmatic condition. In this study, we looked for evidence of oxidative modification of proteins in RAW 264.7 cell line treated with DEP chemicals. We show that the induction of oxidative stress is accompanied by 53 newly expressed proteins which are suppressed by a thiol antioxidant, N-acetylcysteine. These include antioxidant enzymes, pro-inflammatory components, and products of intermediary metabolism. In addition, inducible nitric oxide synthase (iNOS) was identified as a biologically relevant oxidative stress protein that is induced concurrent with increased NO production and protein tyrosine-nitration in DEP-exposed RAW 264.7 cells. Utilizing two-dimensional gel electrophoresis, anti-nitrotyrosine immunoblotting, and mass spectrometry led to the identification of an additional ten nitrotyrosine modified proteins, including oxidative stress proteins involved in intermediary metabolism (e.g., GAPDH and enolase), antioxidant defense (e.g., MnSOD) and inhibition of proteosomal activity (e.g., Hsp 90alpha). These oxidative proteins may serve as markers for oxidative stress generation in vivo. 相似文献
42.
溶胶凝胶法制氧化铝负载铜基超细粒子催化剂的研究 总被引:9,自引:1,他引:9
采用溶胶凝胶法制氧化铝负载铜基超细粒子催化剂的制备了氧化铝负载的铜基超细粒子催化剂,用TG-DTA,XRD,BET以及TEM等技术手段,对催化剂的物相结构,表面孔结构,粒子形貌以及催化性能等进行了研究。结果表明,利用溶胶凝胶法,可以直接帛备出高比表面积,低堆积密度的纤维状纳米级负载型Cu/Al2O3超细粒子;活性组分以远低于纳米级的微晶粒子簇状态,均匀地分散在纳米级氧化铝载体表面上,而且在低于50 相似文献
43.
Control of the optical properties of gel-derived oxide films containing fine metal particles is described. The duration of the aging of Si(OC2H5)4-derived sols and the amount of water for hydrolyzing Si(OC2H5)4 were found to greatly affect the size and the shape of Au particles formed in the silica matrix, and accordingly the optical absorption of the Au/SiO2 composite films. Employing dielectric media with high refractive indices like TiO2 was shown to shift the absorption peak of Au particles to longer wavelengths. Pd/TiO2 and Pt/TiO2 composite films showed absorption in the visible region. 相似文献
44.
45.
In comparison to the corresponding single-component counterparts, core/shell particles are widely used due to their better physical and chemical properties. The surface properties of core/shell particles evidently play an important role in the process of application. It is easy to deduce that surface properties mostly depend on the properties of the component in the shell. Therefore, desirable materials of shell are very significant for the study of composite materials, especially in core/shell field. It is well known that polysiloxane has excellent properties, such as the water repellency, high flexibility, low surface energy, and biocompatibility. Its application, however, is limited due to poor cohesiveness and poor film-forming properties. Recently, much endeavor has been made to overcome such flaws. It is found that polyacrylate is commonly considered for its good cohesiveness and excellent film-forming property. The combination of polysiloxane and polyacrylate has been shown to be important in the composite material field, especially as core/shell particles. Unfortunately, their hydrophobicity is considerably different and thus, the core/shell particles consisting of polyacrylate (PA)/polysiloxane (PSi) are hard to prepare by general seeded emulsion polymerization, and are also scarcely available in the literature. In this study, the new core/shell PA/PSi particles with poly(butyl methacrylate) (PA) as the core and poly(3-(methacryloxypropyl)-trimethoxysilane) (PSi) as the shell were prepared by dispersion polymerization under the kinetically controlled conditions. The characterization of the particles by TEM, DSC, particle size analyzer as well as static contact angle confirmed the formation of core/shell structure. The application of core/shell (PA/PSi) particles also has been considered and discussed here.TEM micrographs of core/shell (PA/PSi) particles. 相似文献
46.
Yong Zhong DU Fu Qiang HU Hong YUAN Shinzo OMI 《中国化学快报》2006,17(4):553-556
Stable poly(styrene-co-sodium styrene sulfonate) (P(St-NaSS) nanoparticles with broader size distribution were synthesized by thermal emulsion polymerization without any conventional initiators and emulsifiers. The obtained polymer nanoparticles have higher ξ potential, and the particle sizes have broad distribution. The stability of polymer particles originated from the addition of small amounts of ionic comonomer, NaSS, which can act as an emulsifier in somewhat. The monomer conversion could reach up to about 28 wt% in 48 h, and did not increase by further polymerization when higher polymerization temperature (120 ℃) was employed. This polymerization system may be give some further understand for mechanism of emulsion polymerization. 相似文献
47.
KaiKANG ChengYouKAN YiDU YuZhongLI DeShanLIU 《中国化学快报》2005,16(6):831-834
Soap-flee P(MMA-EA-MAA) particles with narrow size distribution were synthesized by seeded emulsion polymerization of methyl methacrylate (MMA), ethyl acrylate (EA) and methacrylic acid (MAA), and large voids inside the particles were generated by alkali posttreatment in the presence of 2-butanone. Results indicated that the size of void and theparticle volume were related with the amount of 2-butanone. The generation mechanism of voids was proposed. 相似文献
48.
The crystal habit of fcc metal particles formed on an amorphous carbon film electrode in solution at different electrode
potentials is discussed. The fcc metal particles have different crystallographic habits depending on applied electrode potential;
that is, icosahedral and/or decahedral particles are formed at lower potentials, and fcc single-crystalline or polycrystalline
particles at higher potentials. It was found that decahedra and icosahedra of Cu-Au alloy particles are formed in the potential
region of underpotential deposition (UPD) of Cu at which only fcc Au single-crystalline particles and Au polycrystalline particles
appear. This is attributed to the charge transfer from the UPD Cu ions to the Au overlayer of Cu-Au alloy particles. The formation
of decahedral and icosahedral Cu-Au alloy particles depends on the composition of the Cu-Au alloy. On the basis of these results
it was deduced that the contraction of the surface lattice of the growing particles is responsible for the formation of icosahedral
and decahedral particles.
Received: 25 February 1997 / Accepted: 21 April 1997 相似文献
49.
50.
《Surface and interface analysis : SIA》2003,35(3):310-317
Carbonate is a somewhat enigmatic anion in static secondary ion mass spectrometry (SIMS) because abundant ions containing intact CO32? are not detected when analyzing alkaline‐earth carbonate minerals common to the geochemical environment. In contrast, carbonate can be observed as an adduct ion when it is bound with alkali cations. In this study, carbonate was detected as the adduct Na2CO3·Na+ in the spectra of sodium carbonate, bicarbonate, hydroxide, oxalate, formate and nitrite and to a lesser extent nitrate. The appearance of the adduct Na2CO3·Na+ on hydroxide, oxalate, formate and nitrite surfaces was interpreted in terms of these basic surfaces fixing CO2 from the ambient atmosphere. The low abundance of Na2CO3·Na+ in the static SIMS spectrum of sodium nitrate, compared with a significantly higher abundance in salts having stronger conjugate bases, suggested that the basicity of the conjugate anions correlated with aggressive CO2 fixation; however, the appearance of Na2CO3·Na+ could not be explained simply in terms of solution basicity constants. The oxide molecular ion Na2O+ and adducts NaOH·Na+ and Na2O·Na+ also constituted part of the carbonate spectral signature, and were observed in spectra from all the salts studied. In addition to the carbonate and oxide ions, a low‐abundance oxalate ion series was observed that had the general formula Na2?xHxC2O4·Na+, where 0 < x < 2. Oxalate adsorption from the laboratory atmosphere was demonstrated but the oxalate ion series also was likely to be formed from reductive coupling occurring during the static SIMS bombardment event. The remarkable spectral similarity observed when comparing the sodium salts indicated that their surfaces shared common chemical speciation and that the chemistry of the surfaces was very different from the bulk of the particle. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献