H14[NaP5W30O110] as a heterogeneous recyclable catalyst for the air oxidation of thiols under solvent free conditions. (1/5)

The catalytic oxidation of thiols to the corresponding disulfides using Preyssler's catalyst H(14)[NaP(5)W(30)O(110)] has been studied. These highly selective oxidations gave good yields of the target disulfides.  (+info)

Evaluation of polyphenolic profile and nutritional value of non-traditional fruit species in the Czech Republic--a comparative study. (2/5)

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P6981, an arylstibonic acid, is a novel low nanomolar inhibitor of cAMP response element-binding protein binding to DNA. (3/5)

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Atmospheric acid gases in Tokushima, Japan, monitored with parallel plate wet denuder coupled ion chromatograph. (4/5)

During the summer of 2011 and winter of 2012, we continuously measured trace acid gas concentrations in Tokushima, Japan, using a parallel plate wet denuder coupled ion chromatograph. The average concentrations of hydrochloric acid (HCl), nitrous acid (HONO), nitric acid (HNO(3)), and sulfur dioxide (SO(2)) were, respectively, 0.54, 1.20, 1.17, and 3.22 mug m(-3) in the summer, and 0.09, 1.06, 0.46, and 5.11 mug m(-3) in the winter. In the summer, concentrations of all the acid gases increased after sunrise and showed a strong diurnal pattern with daytime maxima and nighttime minima, but the time at which concentration levels began to increase and the pace of increase differed among the acid gases. The concentration of HONO increased sharply immediately after sunrise, while concentrations of the other three gases began increasing about one and half hours later. SO(2) showed the fastest rate of increase, followed by HNO(3) and HCl. These differences were likely attributable to the formation processes of gaseous substances.  (+info)

A low pH-inducible, PhoPQ-dependent acid tolerance response protects Salmonella typhimurium against inorganic acid stress. (5/5)

The acid tolerance response enables Salmonella typhimurium to survive exposures to potentially lethal acidic environments. The acid stress imposed in a typical assay for acid tolerance (log-phase cells in minimal glucose medium) was shown to comprise both inorganic (i.e., low pH) and organic acid components. A gene previously determined to affect acid tolerance, atbR, was identified as pgi, the gene encoding phosphoglucoisomerase. Mutations in pgi were shown to increase acid tolerance by preventing the synthesis of organic acids. Protocols designed to separate the stresses of inorganic from organic acids revealed that the regulators sigma38 (RpoS), Fur, and Ada have major effects on tolerance to organic acid stress but only minor effects on inorganic acid stress. In contrast, the two-component regulatory system PhoP (identified as acid shock protein ASP29) and PhoQ proved to be important for tolerance to inorganic [corrected] acid stress but had little effect against organic acid stress. PhoP mutants also failed to induce four ASPs, confirming a role for this regulator in acid tolerance. Acid shock induction of PhoP appears to occur at the transcriptional level and requires the PhoPQ system. Furthermore, induction by acid occurs even in the presence of high concentrations of magnesium, the ion known to be sensed by PhoQ. These results suggest that PhoQ can sense both Mg2+ and pH. Since phoP mutants are avirulent, the low pH activation of this system has important implications concerning the pathogenesis of S. typhimurium. The involvement of four regulators, two of which are implicated in virulence, underscores the complexity of the acid tolerance stress response and further suggests that features of acid tolerance and virulence are interwoven.  (+info)