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Oil shale (OS) is a particularly promising alternative fossil fuel source. However, very different from coal, its inorganic mineral content is very high. The organic matters (mainly kerogen) are finely distributed in the inorganic minerals. Therefore, the minerals may affect the processing of OS, whose elucidation is critical to the choice of processing conditions. In this work, different minerals (SiO2, CaCO3, and Al2O3) were added to OS with different mass ratios of OS to mineral, respectively. Then, the thermogravimetric (TG) technique was employed to analyze the reaction behavior of these different OS/mineral mixtures in N2and in air for studying the influence of minerals on the OS pyrolysis in N2(i.e., retorting) and on the OS combustion in air. The results show that CaCO3and Al2O3have a promoting effect on both pyrolysis and combustion of OS, and they can decrease the reaction activation energy of both kinds of processes. However, SiO2has an inhibitive effect and can increase the reaction activation energy for both kinds of processes. It is hoped that the present study can further increase the understanding toward the effect of different minerals on the OS reactions. [ABSTRACT FROM PUBLISHER]

DNA phosphorothioate (PT) modifications, with one non-bridging phosphate oxygen replaced with sulfur, are widely but sporadically distributed in prokaryotic genomes. Short consensus sequences surround the modified linkage in each strain, although each site is only partially modified. The mechanism that maintains this low-frequency modification status is still unknown. In Salmonella enterica serovar Cerro 87, PT modification is mediated by a four-gene cluster called dptBCDE. Here, we found that deletion of dptB led to a significant increase in intracellular PT modification level. In this deletion, transcription of downstream genes was elevated during rapid cell growth. Restoration of dptB on a plasmid restored wild-type levels of expression of downstream genes and PT modification. In vitro, DptB directly protected two separate sequences within the dpt promoter region from DNase I cleavage. Each protected sequence contained a direct repeat (DR). Mutagenesis assays of the DRs demonstrated that each DR was essential for DptB binding. The observation of two shifted species by gel-shift analysis suggests dimer conformation of DptB protein. These DRs are conserved among the promoter regions of dptB homologs, suggesting that this regulatory mechanism is widespread. These findings demonstrate that PT modification is regulated at least in part at the transcriptional level. [ABSTRACT FROM AUTHOR]

Prokaryotes protect their genomes from foreign DNA with a diversity of defence mechanisms, including a widespread restriction-modification ( R- M) system involving phosphorothioate ( PT) modification of the DNA backbone. Unlike classical R- M systems, highly partial PT modification of consensus motifs in bacterial genomes suggests an unusual mechanism of PT-dependent restriction. In S almonella enterica, PT modification is mediated by four genes dptB-E, while restriction involves additional three genes dptF-H. Here, we performed a series of studies to characterize the PT-dependent restriction, and found that it presented several features distinct with traditional R- M systems. The presence of restriction genes in a PT-deficient mutant was not lethal, but instead resulted in several pathological phenotypes. Subsequent transcriptional profiling revealed the expression of > 600 genes was affected by restriction enzymes in cells lacking PT, including induction of bacteriophage, SOS response and DNA repair-related genes. These transcriptional responses are consistent with the observation that restriction enzymes caused extensive DNA cleavage in the absence of PT modifications in vivo. However, overexpression of restriction genes was lethal to the host in spite of the presence PT modifications. These results point to an unusual mechanism of PT-dependent DNA cleavage by restriction enzymes in the face of partial PT modification. [ABSTRACT FROM AUTHOR]

Supported gold (Au) catalysts appear attractive for the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol, a promising method for eliminating 4-NP pollutant in water media. Selecting an appropriate support is a crucial step for obtaining supported Au catalysts with excellent activity. Herein, we demonstrate for the first time that cyanuric acid-based material (CAM) is an appropriate support material, where Au/CAM catalysts catalyze the 4-NP reduction in water at room temperature. The reaction time for complete conversion of 4-NP can be reduced by ~ 10 times to even two orders of magnitude compared to some other reported supported Au catalysts and depending on the reaction conditions used. Moreover, CAM can be obtained using an extremely simple and green synthesis method. [ABSTRACT FROM AUTHOR]

Abstract: Actinomycete species from many genera often harbor linear plasmids and some contain linear chromosomes. A self-ligation and PCR-sequencing method was developed for identifying three novel telomere sequences of linear plasmids of Streptomyces and Mycobacterium. This and four previously described methods for actinomycetes telomere cloning and sequencing are discussed. [Copyright &y& Elsevier]

Oil shale (OS), from which petroleum-like shale oil can be obtained via retorting, is one of the most promising alternative fossil fuels due to its huge reserve. A main obstacle to OS retorting is the required high-energy input, particularly for underground retorting. Recently a low-energy-input route via self-heating retorting (SHR) was developed (Guo et al., 2013 and 2014). However, its unclear reaction mechanism hinders its further development. Herein, the reaction mechanism of SHR was analyzed by using Huadian OS and thermal analysis techniques. The results suggest anaerobic retorting (AR) used for preparing shale oil produces substantial residual carbon (RC) byproduct, and the heat contained in RC is more than the energy input needed by an AR process. While in SHR process, by reaction-kinetics control, part of kerogen is first pyrolized into oil and RC before exposed to air, and then RC in-situ reacts with the diffused air to release heat for progressing SHR and replacing external heat supply. In-situ utilizing RC by SHR process partly explains why SHR itself provides heat to increase retorting temperature but without obviously lost shale-oil yield. [ABSTRACT FROM AUTHOR]

A wide variety of prokaryotes possess DNA modifications consisting of sequence-specific phosphorothioates (PT) inserted by members of a five-gene cluster. Recent genome mapping studies revealed two unusual features of PT modifications: short consensus sequences and partial modification of a specific genomic site in a population of bacteria. To better understand the mechanism of target selection of PT modifications that underlies these features, we characterized the substrate recognition of the PT-modifying enzymes termed DptC, D and E in a cell extract system from Salmonella. The results revealed that double-stranded oligodeoxynucleotides underwent de novo PT modification in vitro, with the same modification pattern as in vivo, i. e., GpsAAC/GpsTTC motif. Unexpectedly, in these in vitro analyses we observed no significant effect on PT modification by sequences flanking GAAC/GTTC motif, while PT also occurred in the GAAC/GTTC motif that could not be modified in vivo. Hemi-PT DNA also served as substrate of the PT-modifying enzymes, but not single-stranded DNA. The PT-modifying enzymes were then found to function as a large protein complex, with all of three subunits in tetrameric conformations. This study provided the first demonstration of in vitro DNA PT modification by PT-modifying enzymes that function as a large protein complex. [ABSTRACT FROM AUTHOR]