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101.
102.
Juliette Blanchard Rachel P. Doherty Hiu-Ying Law Christophe Méthivier Cyril Thomas 《Topics in Catalysis》2013,56(1-8):134-139
The influence of the addition of W to Al2O3, promoted or not by Ag, on the n-C10 SCR of NO x was investigated. It was shown that the addition of W was detrimental to the n-C10 SCR reaction. Based on the NO x -TPD, the XPS and the n-C10 SCR measurements, it was concluded that the loss of activity observed at temperatures lower than 400 °C on the Ag/W(5)–Al2O3 catalyst compared with the Ag/Al2O3 sample is likely due to the preferential deposition of Ag on the tungstate phase, making it inactive for the n-C10 SCR reaction which requires the active silver species to be in close contact with the Al2O3. At higher temperatures, the occupation, by the tungstates, of the Al2O3 sites responsible for the n-C10-SCR reaction is proposed to be an additional drawback accounting for the detrimental effect of W on Al2O3-supported catalysts promoted or not by Ag. 相似文献
103.
The optimization of processes described by non-linear distributed parameter systems is investigated. In general, the complexity of such a problem prevents the implementation of classical deterministic optimization methods. In fact, for global optimization problems as well as for problems involving very large number of variables for which the reduction of the computational time is crucial, these methods can be inefficient. In this framework, several minimization algorithms (deterministic, stochastic, evolutionary) are compared. An application to optimal control determination is presented for a class of distributed parameter systems called spreadable systems. 相似文献
104.
R Steinberg P Brun J Souilhac I Bougault R Leyris G Le Fur P Soubrié 《Canadian Metallurgical Quarterly》1995,28(1):43-50
Changes in bronchoalveolar lavage fluid (BALF) and blood were examined to assess the toxic effects of diborane (B2H6, CAS: 19287-45-7) on the lung. Male Wistar rats were exposed to diborane at 20 ppm (intended concentration) for 4 h (phase I study) to evaluate time-course changes up to 14 days, and at 10 or 1 ppm (intended concentrations) to assess the dose-effect relationship after 3 days (phase II study). BALF parameters [leukocyte counts, alpha 1-antitrypsin (alpha 1-AT), superoxide dismutase (SOD), total protein, phospholipids etc.] were examined and biochemical and histopathological studies were also carried out. In the phase I study, neutrophils (%) in BALF increased on the day of exposure and then decreased gradually for 3 days. Rapid and marked increases in alpha 1-AT and SOD activity in BALF were detected on the day of exposure, and phospholipids had sharply increased on day 3. After 14 days, these parameters in the exposed rats had returned to their background level and alpha 1-AT decreased significantly. In the phase II study, total protein, alpha 1-AT activity and phospholipids in BALF showed dose-dependent increases, and serum alpha 1-AT activity increased significantly. Alveolar capillary and alveolar cell damage were confirmed in rats exposed to 20 ppm, 10 ppm or 1 ppm diborane for 4 h by evaluating the parameters examined. The protection system appeared to start operating immediately after exposure, and the recovery mechanism seemed to start operating 1 day after exposure and cease by day 14. The no-observed-effect level could not be observed. 相似文献
105.
Han SI Garcia S Lowery TJ Ruiz EJ Seeley JA Chavez L King DS Wemmer DE Pines A 《Analytical chemistry》2005,77(13):4008-4012
Laser-enhanced (LE) 129Xe nuclear magnetic resonance (NMR) is an exceptional tool for sensing extremely small physical and chemical changes; however, the difficult mechanics of bringing polarized xenon and samples of interest together have limited applications, particularly to biological molecules. Here we present a method for accomplishing solution 129Xe biosensing based on flow (bubbling) of LE 129Xe gas through a solution in situ in the NMR probe, with pauses for data acquisition. This overcomes fundamental limitations of conventional solution-state LE 129Xe NMR, e.g., the difficulty in transferring hydrophobic xenon into aqueous environments, and the need to handle the sample to refresh LE 129Xe after an observation pulse depletes polarization. With this new method, we gained a factor of >100 in sensitivity due to improved xenon transfer to the solution and the ability to signal average by renewing the polarized xenon. Polarized xenon in biosensors was detected at very low concentrations, =250 nanomolar, while retaining all the usual information from NMR. This approach can be used to simultaneously detect multiple sensors with different chemical shifts and is also capable of detecting signals from opaque, heterogeneous samples, which is a unique advantage over optical methods. This general approach is adaptable for sensing minute quantities of xenon in heterogeneous in vitro samples, in miniaturized devices and should be applicable to certain in-vivo environments. 相似文献
106.
Microarray analysis reveals a mechanism of phenolic polybrominated diphenylether toxicity in zebrafish 总被引:1,自引:0,他引:1
van Boxtel AL Kamstra JH Cenijn PH Pieterse B Wagner JM Antink M Krab K van der Burg B Marsh G Brouwer A Legler J 《Environmental science & technology》2008,42(5):1773-1779
Polybrominated diphenylethers (PBDEs) are ubiquitous in the environment, with the lower brominated congener 2,2',4,4'-tetrabromodiphenylether (BDE47) among the most prevalent. The phenolic PBDE, 6-hydroxy-BDE47 (6-OH-BDE47) is both an important metabolite formed by in vivo metabolism of BDE47 and a natural product produced by marine organisms such as algae. Although this compound has been detected in humans and wildlife, including fish, virtually nothing is known of its in vivo toxicity. Here we report that 6-OH-BDE47 is acutely toxic in developing and adult zebrafish at concentrations in the nanomolar (nM) range. To identify possible mechanisms of toxicity, we used microarray analysis as a diagnostic tool. Zebrafish embryonic fibroblast (PAC2) cells were exposed to 6-OH-BDE47, BDE47, and the methoxylated metabolite 6-MeO-BDE47. These experiments revealed that 6-OH-BDE47 alters the expression of genes involved in proton transport and carbohydrate metabolism. These findings, combined with the acute toxicity, suggested that 6-OH-BDE47 causes disruption of oxidative phosphorylation (OXPHOS).Therefore, we further investigated the effect of 6-OH-BDE47 on OXPHOS in zebrafish mitochondria. Results show unequivocally that this compound is a potent uncoupler of OXPHOS and is an inhibitor of complex II of the electron transport chain. This study provides the first evidence of the in vivo toxicity and an important potential mechanism of toxicity of an environmentally relevant phenolic PBDE of both anthropogenic and natural origin. The results of this study emphasize the need for further investigation on the presence and toxicity of this class of polybrominated compounds. 相似文献
107.
Polyphenol‐rich grape pomace extracts protect against dextran sulfate sodium‐induced colitis in rats
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108.
109.
Cecilia Virginia Gheran Sorina Nicoleta Voicu Bianca Galateanu Mait Callewaert Juliette Moreau Cyril Cadiou Franoise Chuburu Anca Dinischiotu 《International journal of molecular sciences》2022,23(6)
The aim of this study was to investigate the biocompatibility of contrast agents, such as gadolinium 1, 4, 7, 10 tetraazacyclo-dodecane tetraacetic acid (GdDOTA) and gadolinium dioctyl terephthalate (GdDOTP), encapsulated in a polymeric matrix containing chitosan and hyaluronic acid using RAW264.7 murine macrophages and human blood samples. The cell viability and cytotoxicity were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays, while cell cycle analysis was determined in RAW264.7 cells using flow cytometry. The mitochondrial membrane potential (MMP), hemolytic index, complement activation, and thrombogenic potential of gadolinium (Gd) containing nanohydrogels were measured by fluorometric and spectrophotometric methods. Taken together, our results demonstrate the good bio- and hemocompatibility of chitosan-based nanohydrogels with the RAW264.7 cell line and human blood cells, suggesting that these could be used as injectable formulations for the magnetic resonance imaging diagnostic of lymph nodes. 相似文献