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Isolation and cryopreservation of freshly isolated hepatocytes is considered a standard procedure for the long-term storage of liver cells. However, most existing methods for banking hepatocytes do not allow sufficient recovery of viable cells to meet the needs of basic research or clinical trials of hepatocyte transplantation. The mechanisms underlying this poor rate of hepatocyte recovery are unknown. Although much of the cellular damage in freezing is caused by formation of ice crystals within the cells, this is largely prevented by the use of dimethyl sulfoxide (DMSO) and controlled rate freezing. As we demonstrated recently, necrosis does occur in primary hepatocytes following isolation and cryopreservation. In the present study, we explored the contribution of apoptosis, another form of cell death, in primary hepatocytes banked for transplantation. We evaluated apoptosis of C57BL/6J mouse primary hepatocytes using several different methods. Annexin binding and the TUNEL assay, in conjunction with flow cytometry and confocal laser scanning microscopy, revealed that the percentage of apoptotic cells was dramatically elevated in cryopreserved cells compared with that in the control group of unfrozen cells. DNA laddering detected by DNA electrophoresis in agarose gel also supported the presence of apoptosis in isolated and banked liver cells. Moreover, we found that the addition of glucose (from 10 to 20 mM) into the freezing solution (University of Wisconsin Solution) decreased the rate of apoptosis by 84% and improved the cell attachment at least fourfold in cryopreserved cells. These results suggest that apoptosis might contribute to cell death in isolated and banked primary hepatocytes.

Abstract: Present paper describes the influence of the incorporation of alkali metal cations (AM=Li, Na, K, Cs; and an AM/V ratio of 0.04) and Na-content (Na/V ratio of 0.02–0.30) in alkali metal promoted V2O5 catalyst on both the catalyst structure and the catalytic performance in H2S partial oxidation reactions. The catalytic activity depends on the alkali metal and the amount of alkali metal added, although Na-containing catalysts seem to be the more active ones. However, selectivity to sulphur higher than 98% is achieved in the main of catalysts when working at reaction temperature lower than 220°C. According to the characterization results of used catalysts, V4O9 is selectively formed during the catalytic tests on catalysts presenting V2O5 crystallites. In catalysts with Na/V ratios higher than 0.04, V4O9 and Na0.33V2O5 are observed, the presence of Na0.33V2O5 increasing when increasing the Na/V ratio. Accordingly, V4O9 and Na0.33V2O5 can be proposed as the active and selective crystalline phase in Na-containing catalysts. The role of the presence of V4+−O–V5+ pairs in partial oxidation of H2S is also discussed. [Copyright &y& Elsevier]

Abstract: The modification of crystalline phases of a vanadium oxide supported on mesoporous zirconium phosphate during the partial oxidation of H2S to sulphur has been studied by using an operando Raman-GC approach and XAS in reaction conditions. The catalyst, mainly presenting crystalline V2O5, is transformed during the oxidation of H2S at 200°C, presenting crystals of V4O9, which is identified by the presence of a band at ca. 900cm−1 in the Raman spectra (using a 785nm line of an Argon ion laser) and by the presence of a pre-edge at 5469.8eV (and a main-edge at 5482.2eV) in XANES spectra. At the same time, it is observed a high conversion of H2S to sulphur (the main reaction product) and SO2 (as minority). Both activity and selectivity depend on the time on stream. In this way, the selectivity to SO2 decreases from ca. 5 to 1% with the time on stream. This change could be explained on the basis of the nature of V-species: the initial presence of V5+–O–V5+ pairs and the appearance of V5+–O–V4+ pairs at high time on stream. [ABSTRACT FROM AUTHOR]

Catalysts consisting of NiO diluted in high surface area TiO 2 can be as efficient in the oxidative dehydrogenation of ethane as the most selective NiO-promoted catalysts reported previously in the literature. By selecting the titania matrix and the NiO loading, yields to ethylene over 40% have been obtained. In the present article, three different titanium oxides (TiO 2 ) have been employed as supports or diluters of nickel oxide and have been tested in the oxidative dehydrogenation of ethane to ethylene. All TiO 2 used present anatase as the main crystalline phase and different surface areas of 11, 55 and 85 m 2 g −1 . It has been observed that by selecting an appropriate nickel loading and the titanium oxide extremely high selectivity towards ethylene can be obtained. Thus, nickel oxide supported on TiO 2 with high surface areas (i.e. 55 and 85 m 2 g −1 ) have resulted to give the best catalytic performance although the optimal nickel loading is different for each case. The optimal catalyst has been obtained for NiO-loadings up to 5–10 theoretical monolayers regardless of the TiO 2 employed. Free TiO 2 is inactive whereas unsupported NiO is active and unselective (forming mainly carbon dioxide) and, therefore, unmodified NiO particles have to be avoided in order to obtain the optimal catalytic performance. The use of low surface area titania (11 m 2 g −1 ) have led to the lowest selectivity to olefin due to the presence of an excess of free NiO particles. [ABSTRACT FROM AUTHOR]

Highlights: [•] CRM 125-A is a 5.4g UO2 pellet assay and isotopic standard (4% enriched in 235U). [•] The CRM 125-A UO2 pellet is being developed as a CRM for U–Th age determinations. [•] The U isotopic composition is determined by TIMS using 3 independent methods. [•] Re-certification of CRM 125-A has resulted in significantly smaller uncertainties for the U minor isotope-amount ratios. [•] The revised values for CRM 125-A are provided in a new certificate of analysis. [ABSTRACT FROM AUTHOR]