-The-impact-of-chloride-on-the-decomposition-of-shortchain-carboxylic-acid-intermediates-from-aromatics-degradation-has-often-been-overlooked-j

In this study the roles of chloride in the oxidation of maleic acid (MA) in the Fe(II)/peroxymonosulfate (PMS) process was investigated. Degradation efficiency, reaction intermediates, adsorbable organic halogen (AOX) accumulation and mineralization were examined. The chloride ion (Cl-) was found to have an overall negative impact on MA degradation and mineralization in the Fe(II)/PMS system. The presence of Cl- led to the formation of chlorinated by-products and a high production of AOX. The mineralization of MA was decreased with increasing Cl- concentrations. Kinetic modeling demonstrated the impact of various radicals largely depended on the concentration of Cl-.

The significance of Cl2•- or Cl2 for MA destruction was enhanced with increasing Cl- content, and overwhelmed that of SO4•- when the Cl- concentration was over 5 mM. In the absence of Cl-, SO4•- was the primary radical responsible for MA oxidation. A possible degradation pathway is proposed (cis-trans isomerization, decarboxylation and halogenations processes). These results may help to understand the full oxidation pathways of refractory aromatic compounds and the mechanism of chlorinated by-products formation in industrial saline wastewater treatment.The identification of the A-type RNA helices in a 55mer RNA by selective incorporation of deuterium-labelled nucleotide residues (Uppsala NMR-window The 55-nt long RNA, modelling a three-way junction, with non-uniformly incorporated deuterated nucleotides has been synthesised in a pure form. The NMR-window part in this partially deuterated 55mer RNA consists of natural non-enriched nucleotide blocks at the three-way junction (shown in a square box in Fig. 2), whereas all other nucleotides of the rest of the molecule are partially deuterated (> 97 atom% 2H at C2', C3', C5', C5, and approximately 50 atom% 2H at C4').

The secondary structure of this 55mer RNA was determined by 2D 1H NOESY spectroscopy in D2O or in 10% D2O-H2O mixture. The use of deuterated building blocks in the specific region of the 55mer RNA allowed us to identify two distinct A-type RNA helices in a straightforward manner by observing connectivities of H1' with the basepaired imino and the aromatic H2 of all adenosine nucleotides as the first step for the determination of its tertiary structure in a cost- and time-effective manner without employing any 13C/15N labelling. These two decameric helices involve 40 nucleotides, for which all non-exchangeable H1', H6, H2, H8 and H5 protons (all 40 H1', all 40 H6 or H8 aromatics, all seven H2 of adenine nucleotide and all four non-deuterated H5 of cytosines) as well as all 16 exchangeable imino protons (with the exception of four terminal basepairs) and 16 amino protons of cytosines have been assigned. Since all aromatic-H2', H3' as well as H5'/5 crosspeaks from partially deuterated residues have been eliminated from the NMR spectra, the observation of natural nucleotide residues in the NMR window part has essentially been simplified. salcaprozate has been found that the crosspeaks from the natural nucleotides located at the three-way junction in the NMR-window part show different degrees of line-broadening, thereby indicating that the various nucleotide residues have very different mobilities with respect to themselves as well as compared to other nucleotides in the helices. The assignment of H2' and H3' in the NMR-window part has been made based on NOESY and DQF-COSY crosspeaks. It is noteworthy that, even in this preliminary study, it has been possible to identify 10 H2' out of total 14 and 9 H3' out of 14.

The data show that expanded AU containing a tract of 55mer RNA does not self-organise into a tight third helix, as the two decameric A-type helices, across the three-way junction which is evident from the absence of any additional imino protons, except those that already have been assigned for the two decameric helices.Molecular insights into the chemodiversity of dissolved organic matter and its interactions with the microbial community in eco-engineered bauxite residue.Ecosystems Observation and Research Station, Ministry of Education, Guizhou, Restoration Technology Engineering Research Centre, Guizhou University, Guiyang, Dissolved organic matter (DOM) plays an important role in the biogeochemical function development of bauxite residue. Nevertheless, the DOM composition at the molecular level and its interaction with microbial community during soil formation of bauxite residue driven by eco-engineering strategies are still relatively unknown. In the present study, the DOM composition at the molecular level and its interactions with the microbial community in amended and revegetated bauxite residue were explored.