Social and Behavioral Sciences Commons^™

Oxidation Of Acid-Volatile Sulfide In Surface Sediments Increases The Release And Toxicity Of Copper To The Benthic Amphipod Melita Plumulosa, Stuart L. Simpson, Daniel Ward, David Strom, Dianne F. Jolley

Faculty of Science - Papers (Archive)

Acid-volatile sulfides (AVS) are an important metal-binding phase in sediments. For sediments that contain an excess of AVS over simultaneously extracted metal (SEM) concentrations, acute or chronic effects should not result from the metals Cd, Cu, Ni, Pb and Zn. While AVS phases may exist in surface sediments, the exposure to dissolved oxygen may oxidize the AVS and release metals to more bioavailable forms. We investigated the role of oxidation of AVS, and specifically copper sulfide phases, in surface sediments, in the toxicity to juveniles of the epibenthic amphipod, Melita plumulosa. Sediments containing known amounts of copper sulfide were prepared …

Binaphthyl-Anchored Antibacterial Tripeptide Derivatives With Hydrophobic C-Terminal Amino Acid Variations, John Bremner, Paul A. Keller, Stephen Pyne, Mark Robertson, Kandasamy Sakthivel, Kittiya Somphol, Dean Baylis, Jonathon A Coates, John Deadman, Dharshini Jeevarajah, David I. Rhodes

Faculty of Science - Papers (Archive)

The facile synthesis of seven new dicationic tripeptide benzyl ester derivatives, with hydrophobic group variations in the C-terminal amino acid component, is described. Moderate to good activity was seen against Gram-positive bacteria in vitro. One cyclohexyl-substituted compound 2c was tested more widely and showed good potency (MIC values ranging from 2–4 μg/mL) against antibiotic-resistant strains of Staphylococcus aureus and Enterococci (VRE, VSE), and against Staphylococcus epidermidis.

Satellite Evidence For A Large Source Of Formic Acid From Boreal And Tropical Forests, T Stavrakou, J F. Muller, J Peeters, A Razavi, L Clarisse, C Clerbaux, P Coheur, D Hurtmans, M De Maziere, C Vigouroux, Nicholas Deutscher, David Griffith, Nicholas Jones, Clare Paton-Walsh

Faculty of Science - Papers (Archive)

Formic acid contributes significantly to acid rain in remote environments1, 2. Direct sources of formic acid include human activities, biomass burning and plant leaves. Aside from these direct sources, sunlight-induced oxidation of non-methane hydrocarbons (largely of biogenic origin) is probably the largest source3, 4. However, model simulations substantially underpredict atmospheric formic acid levels5, 6, 7, indicating that not all sources have been included in the models. Here, we use satellite measurements of formic acid concentrations to constrain model simulations of the global formic acid budget. According to our simulations, 100–120 Tg of formic acid is produced annually, which is two …

Crosslinking Neat Ultrathin Films And Nanofibres Of Ph-Responsive Poly(Acrylic Acid) By Uv Radiation, Adrian Gestos, Philip G. Whitten, Geoffrey Maxwell Spinks, Gordon G. Wallace

Faculty of Science - Papers (Archive)

Electrospun polyelectrolyte hydrogel nanofibres are being developed for many applications including artificial muscles, scaffolds for tissue engineering, wound dressings and controlled drug release. For electrospun polyelectrolytes, a post-spinning crosslinking process is necessary for producing a hydrogel. Typically, radiation or thermal crosslinking routines are employed that require multifunctional crosslinking molecules and crosslink reaction initiators (free radical producers). Here, ultraviolet subtype-C (UVC) radiation was employed to crosslink neat poly(acrylic acid) (PAA) nanofibres and films to different crosslink densities. Specific crosslink initiators or crosslinking molecules are not necessary in this fast and simple process providing an advantage for biological applications. Scanning probe microscopy …

Improved Performance Of Porphyrin-Based Dye Sensitised Solar Cells By Phosphinic Acid Surface Treatment, K Sunahara, Alessandra Allegrucci, S Mori, Naomi A. Lewcenko, Leone Spiccia, Attila J. Mozer, Lynn Dennany, Pawel W. Wagner, David L. Officer

Faculty of Science - Papers (Archive)

Chemical surface treatment of porphyrin-sensitised titania films using bis-(4-methoxyphenyl)phosphinic acid after dye adsorption, results in large improvements in DSSC efficiencies which originate primarily from higher short circuit currents. The result was attributed to a positive shift in the TiO2 quasi-Fermi level with simultaneous retardation of charge recombination. High device performances have been achieved even using simplified electrolyte matrices devoid of the common additives, LiI and t-butylpyridine.

Synthesis And Ph-Responsive Properties Of Pseudo-Peptide Containing Hydrophobic Amino Acid Grafts, Rongjun Chen, Mark E. Eccleston, Zhilian Yue, Nighel K. H Slater

Faculty of Science - Papers (Archive)

Pseudo-peptidic polymers have been synthesised by grafting l-valine (PV), l-leucine (PL) and l-phenylalanine (PP) onto the pendant carboxylic acid moieties of a pH-responsive polyamide, poly(l-lysine isophthalamide). The pH-responsive aqueous solution properties of PV-75, PL-75 and PP-75 with a stoichiometric degree of substitution of 75 mol% have been compared with those of the parent poly(l-lysine isophthalamide) using UV-visible and fluorescence spectroscopy. At low concentrations (≤0.1 mg mL-1), the grafted polymers displayed pH-dependent conformation. The pH at the onset of hydrophobic association (pHh) and the pH range over which association occurred varied significantly between the different amino acid grafts. The pHh values …

Direct Ascorbic Acid Detection With Ferritin Immobilized On Single-Walled Carbon Nanotubes, Chonlada Dechakiatkrai, Jun Chen, Carol M. Lynam, Kwang Min Shin, Seon Jeong Kim, Sukon Phanichphant, Gordon G. Wallace

Faculty of Science - Papers (Archive)

Ferritin protein was noncovalently immobilized onto single-walled carbon nanotubes (SWNTs). This SWNT/ferritin composite was characterized using cyclic voltammetry, UV-visible spectroscopy, Raman spectroscopy, and high-resolution transmission electron microscopy. The use of the SWNT/ferritin film as an amperometric biosensor was demonstrated by sensing ascorbic acid in phosphate-buffered saline solution with a sensitivity of 767 uAmg. It demonstrated that ferritin protein bound to SWNTs enhances the oxidation reaction of ascorbic acid over 11-fold.

Syntheses Of Spiro[Cyclopropane-1,3'-Oxindole]-2-Carboxylic Acid And Cyclopropa[C]Quinoline-7b-Carboxylic Acid And Their Derivatives, Sarah Yong, Alison T. Ung, Stephen G. Pyne, Brian W. Skelton, Allan H. White

Faculty of Science - Papers (Archive)

The synthesis of spiro[cyclopropane-1,3′-oxindole]-2-carboxylic acid, including novel 3-(2- and 3-pyridyl)-substituted analogues and the novel cyclopropa[c]quinoline-7b-carboxylic acid and their ester and amide derivatives is described. These syntheses involve diastereoselective cyclopropanation reactions of methyl 2-(2-nitrophenyl)acrylate and (3E)-(pyridin-2-ylmethylene)- and (3E)-(pyridin-3-ylmethylene)-1,3-dihydro-2H-indol-2-one with ethyl (dimethyl sulfuranylidene) acetate (EDSA). The synthesis of methyl cyclopropa[c]quinoline-7b-carboxylate involves a regioselective reductive cyclization of a nitro-diester precursor. The relative stereochemistry of key compounds has been determined by single-crystal X-ray structural analysis.

Nutrigenomics Applied To An Animal Model Of Inflammatory Bowel Diseases: Transcriptomic Analysis Of The Effects Of Eicosapentaenoic Acid-And Arachidonic Acid-Enriched Diets, Nicole Roy, Matthew Barnett, Bianca Knoch, Yvonne Dommels, Warren Mcnabb

Faculty of Science - Papers (Archive)

In vivo models of Inflammatory Bowel Diseases (IBD) elucidate important mechanisms of chronic inflammation. Complex intestinal responses to food components create a unique “fingerprint” discriminating health from disease. Five-week-old IL10−/− and C57BL/6J (C57; control) mice were inoculated orally with complex intestinal microflora (CIF) and/or pure cultures of Enterococcus faecalis and E. faecalis (EF) aiming for more consistent inflammation of the intestinal mucosa. Inoculation treatments were compared to non-inoculated IL10−/− and C57 mice, either kept in specific pathogen free (SPF) or conventional conditions (2×5 factorial design). At 12 weeks of age, mice were sacrificed for intestinal histological (HIS) and transcriptomic analysis …

Molecular Dynamics Simulations Of Peptides Containing An Unnatural Amino Acid: Dimerization, Folding, And Protein Binding, Haibo Yu, Xavier Daura, Wilfred Van Gunsteren

Faculty of Science - Papers (Archive)

We have performed molecular dynamics (MD) simulations to study the dimerization, folding, and binding to a protein of peptides containing an unnatural amino acid. NMR studies have shown that the substitution of one residue in a tripeptide β-strand by the unnatural amino acid Hao (5-HO2CCONH-2-MeO-C6H3-CO-NHNH2) modifies the conformational flexibility of the β-strand and the hydrogen-bonding properties of its two edges: The number of hydrogen-bond donors and acceptors increases at one edge, whereas at the other, they are sterically hindered. In simulations in chloroform, the Hao-containing peptide 9 (i-PrCO-Phe-Hao-Val-NHBu) forms a β-sheet–like hydrogen-bonded dimer, in good agreement with the available experimental …

Applications Of Airborne Laser Scanning To Manage Coastal Acid Sulfate Soils Within The Broughton Creek Floodplain, Marcus Morgan, Warwick Papworth, Peter Aney, John Perry, Buddhima Indraratna

Faculty of Science - Papers (Archive)

Airborne Laser Scanning (ALS) Was first used in 1993 by Geodan Geodesie B. V. as a cheaper alternative in the collection of spatial information than traditional survey methods and photogrammetry. ALS has become important in creating Digital Terrain Models (DTM) with high precision at a far lower cost to other methods. Shoalhaven City Council employed ALS in May 200 I for the purpose of obtaining detailed survey information within budgetary constraints. The aim Was to determine the effectiveness of using ALS for coastal and environmental management by testing the accuracy of ground level points against traditionally surveyed points.

Coastal Acid …