University of South Australia

About: University of South Australia is a education organization based out in Adelaide, South Australia, Australia. It is known for research contribution in the topics: Population & Context (language use). The organization has 10086 authors who have published 32587 publications receiving 913683 citations. The organization is also known as: The University of South Australia & UniSA.

Rethinking clinical trials of transcranial direct current stimulation: participant and assessor blinding is inadequate at intensities of 2mA.

Abstract: Copyright @ 2012 The Authors. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and 85 reproduction in any medium, provided the original author and source are credited. The article was made available through the Brunel University Open Access Publishing Fund.

Arsenic speciation and toxicity in biological systems.

Abstract: Although it is now commonly accepted that toxicity and bioavailability varies with As species, extensive research has been carried out on biological and environmental samples to assess toxicity and risk associated with As exposure based on total concentrations that may be in error. The health investigation guideline for the Australian environmental protection measure is 100 mg/kg (As(tot)), which would cause potential risk to human health if all the As present in a sample were bioavailable (ANZECC 1992). Similarly, the MPC for As in food is 1 mg/ kg (fresh weight), but this concentration may include contributions from As(III), AsV, and all organic species. Thus, a food substance, such as seafood, could have a high total concentration exceeding the guidelines, but most of the As would be in forms that are nontoxic to humans; i.e., the bioavailability is low, and the food would therefore be perfectly safe to eat. On the other hand, a food that has high bioavailability of As consequently is more toxic. Overall, it appears that contamination of water by As is probably more harmful to humans than As in food grains or vegetables, because As bioavailability in water is generally higher than its bioavailability in food. Nevertheless, As in food crops could make significant contribution toward total daily intake. Therefore, failure to consider the contribution of As species on their bioavailability could introduce a substantial bias into the estimation of risks associated with exposure as well as evaluation of As toxicity. In conclusion, As must be regarded as an important environmental toxicant because of its acute and chronic toxic properties and extensive presence in the environment. Much remains to be learned about its toxicology and biochemistry for better understanding of this important contaminant.

Biochar suppressed the decomposition of organic carbon in a cultivated sandy loam soil: A negative priming effect

Abstract: Conversion of plant residues to biochar is an attractive strategy for mitigation of atmospheric carbon dioxide (CO2) emission and enhancement of carbon (C) storage in soil. However, the effect of biochar application on the decomposition of soil organic C (SOC) as well as its mechanisms is not well understood in the sandy loam soil of North China Plain. We investigated how biochar affected the decomposition of native SOC, using stable δ13C isotope analyses by applying biochar produced from corn straw (a C4 plant, δ13C = −11.9‰) to a sandy loam soil (δ13C of SOC = −24.5‰) under a long-term C3 crop rotation. The incubation experiment included four treatments: no amendment (Control), biochar amendment (BC, 0.5% of soil mass), inorganic nitrogen (N) amendment (IN, 100 mg N kg−1) and combined biochar and N amendments (BN). Compared with Control, N amendment significantly (P < 0.05) increased total soil CO2 emission, even when combined with biochar amendment. In contrast, biochar alone amendment did not affect total soil CO2 emission significantly. However biochar, even when combined with N amendment, significantly (P < 0.05) reduced CO2 emission from native SOC by 64.9–68.8%, indicating that biochar inhibited the decomposition of native SOC and the stimulation effect of inorganic N on native SOC degradation, a negative priming effect. N addition immediately stimulated the growth of microorganisms and altered microbial community structure by increasing Gram-positive bacteria compared to Control as measured by phospholipid fatty acid. Biochar amendment did not alter microbial biomass during the 720-h incubation period except at 168 and 720 h, but significantly (P < 0.05) lowered dissolved organic C (DOC) content in soil, primarily due to sorption of DOC by the biochar. Our study suggested that biochar application could effectively reduce the decomposition of native organic C and a potential effective measure for C sequestration in the test soil of the North China Plain.

Atomic Force Microscope Images of Nanobubbles on a Hydrophobic Surface and Corresponding Force-Separation Data

Abstract: Domains, apparently nanobubbles, have been observed on a hydrophobic glass surface in water using an atomic force microscope operated in tapping mode. Phase images show the domains to be softer than the underlying substrate. Complementary force curves between a silica colloid probe and the glass surface display features characteristic of the hydrophobic interaction, including a jump-in distance that is comparable to the height of the imaged domains. Images and force curves have been acquired over a range of pH conditions to probe the nature of the overall interaction and gain some insight into the conformation of nanobubbles on the sample surface. The bubbles appear to regrow following their removal by the application of high loads through either contact mode imaging or tapping mode imaging at high drive amplitudes. They are not present in a solvaphilic fluid (ethanol) but regrow following the subsequent reintroduction of H2O. The correlation between image and force data, supported by existing results in ...

Topical Nano and Microemulsions for Skin Delivery.

Abstract: Nanosystems such as microemulsions (ME) and nanoemulsions (NE) offer considerable opportunities for targeted drug delivery to and via the skin. ME and NE are stable colloidal systems composed of oil and water, stabilised by a mixture of surfactants and cosurfactants, that have received particular interest as topical skin delivery systems. There is considerable scope to manipulate the formulation components and characteristics to achieve optimal bioavailability and minimal skin irritancy. This includes the incorporation of established chemical penetration enhancers to fluidize the stratum corneum lipid bilayers, thus reducing the primary skin barrier and increasing permeation. This review discusses nanosystems with utility in skin delivery and focuses on the composition and characterization of ME and NE for topical and transdermal delivery. The mechanism of skin delivery across the stratum corneum and via hair follicles is reviewed with particular focus on the influence of formulation.