Anion-Tuning of Supramolecular Gel Properties

Low molecular weight gelators (LMWGs) are a class of compounds that has garnered great interest from material, synthetic, supramolecular and biological chemists. Anion tuning of these supramolecular gels is a burgeoning field of study. Two classes of compounds, chiral bisureas and urea derivatised pyrazoles are studied. The synthesized chiral bisurea compounds act as gelators in a variety of solvents. Addition of anions in the form of tetrabutyl ammonium salts was found to afford break up of the gels. Studies reveal that the rheological characteristics of these materials can be tuned using the simple addition of sub-stoichiometric amounts of anion. Variation in the length of the alkyl chain of the spacer separating the chiral and bisurea moieties affects the gel formation of a series of related compounds. Compounds with even numbered spaced alkyl chains were found to gel, whereas the odd numbered spaced alkyl chain compounds did not. Crystal growth within the gel matrix influences the crystallization processes and the use of anion induced break down of the LMWGs allows for easy recovery of the grown crystals. Drug compounds, bound upon gelation of a solution containing the drugs, were found to be released in a controlled manner from the gel matrix. Urea functionalised pyrazoles were synthesized. Crystallographic determination of the hydrogen bonding of the compounds as well as the coordination chemistry of these compounds was obtained. Anion binding studies, in addition to the crystallographic results, reveal that the urea or thiourea groups form an intramolecular hydrogen bond with the pyrazole group resulting in an anti conformation. This prevents formation of gels except in one case. The gelation of 1-(3-methyl-1H-pyrazol-5-yl)-3-(3-nitrophenyl)urea in acidic water overcomes this problem by protonation of the pyrazole group resulting in a syn conformation of the urea group. Anion tuning of the gel properties is revealed where nitrate and chloride result in precipitation of gels and the rheological characteristics can be tuned by changing the anion’s identity

The revision of the Eucharist in the Church of England : a study of liturgical change in the twentieth century.

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN021511 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Stable isotope probing: Technical considerations when resolving ¹⁵N-labeled RNA in gradients

RNA based stable isotope probing (SIP) facilitates the detection and identification of active members of microbial populations that are involved in the assimilation of an isotopically labeled compound. ¹⁵N-RNA-SIP is a new method that has been discussed in recent literature but has not yet been tested. Herein, we define the limitations to using ¹⁵N-labeled substrates for SIP and propose modifications to compensate for some of these shortcomings. We have used ¹⁵N-RNA-SIP as a tool for analysing mixed bacterial populations that use nitrogen substrates. After incubating mixed microbial communities with ¹⁵N-ammonium chloride or ¹⁵N₂ we assessed the fractionation resolution of ¹⁵N-RNA by isopycnic centrifugation in caesium trifluoroacetate (CsTFA) gradients. We found that the more isotopic label incorporated, the further the buoyant density (BD) separation between ¹⁵N- and ¹⁴N-RNA, however it was not possible to resolve the labeled from unlabeled RNA definitively through gradient fractionation. Terminal-restriction fragment length polymorphism (T-RFLP) analysis of the extracted RNA and fluorescent in situ hybridisation (FISH) analysis of the enrichment cultures provided some insight into the organisms involved in nitrogen fixation. This approach is not without its limitations and will require further developments to assess its applicability to other nitrogen-fixing environments

Facilitating re-use of PhD research data

Paper and presentation given at the Open Repositories 2013 conference, 8-12 July 2013, in Charlottetown, Prince Edward Island, Canada.JIS

User Guide for the Deposit of Data to Open Research Exeter (ORE)

This is a draft guide for the deposit of research data to Open Research Exeter using Globus Online. The guide is subject to change.JIS

E-theses Survival Guide for New PGR Students

A guide to E-theses for new PGR students