Spectrofluorimetric Determination of Second Critical Micellar Concentration of SDS and SDS/Brij 30 Systems

Potentially useful stead-state fluorimetric technique was used to determine the critical micellar concentrations (CMC(1) and CMC(2)) for two micellar media, one formed by SDS and the other by SDS/Brij 30. A comparative study based on conductimetric and surfacial tension measurements suggests that the CMC(1) estimated by the fluorimetric method is lower than the value estimated by these other techniques. Equivalent values were observed for SDS micelles without Brij 30 neutral co-surfactant. The use of acridine orange as fluorescent probe permitted to determine both CMC(1) and CMC(2). Based on it an explanation on aspects of micelle formation mechanism is presented, particularly based on a spherical and a rod like structures.

The effect of ultra-low proton concentration on the electrocatalytic reduction of nitrate over platinum

The electrocatalytic reduction of NO3- (aq) over platinum has been investigated in sulfuric acid solutions with proton concentrations between 1 mM and 50 mM. Cyclic voltammetry indicates that for [H+] < 10 mM, NO3- (aq) is reduced in two distinct regions of potential: one reduction peak occurs at approximately 0.1 V vs. RHE and one occurs at -0.13 V vs. RHE. This second reduction peak has never before been observed, and is not present for proton concentrations >10 mM, where hydrogen electroreduction prevails below 0.0 V vs. RHE. Chronoamperometry shows that the kinetics of the two reduction peaks are distinct, suggesting that the two reduction peaks may correspond to the evolution of different products. Results are discussed in the context of tuning the product selectivity of the electrocatalytic reduction of NO3- (aq). (C) 2007 Elsevier B.V. All rights reserved.

The impact of water concentration on the catalytic oxidation of ethanol on platinum electrode in concentrated phosphoric acid

The electro-oxidation of ethanol on platinum in phosphoric acid opens the door to promote the oxidation reaction at higher temperatures. However, the effect of the presence of water is not well understood. In this work, the electro-oxidation of ethanol on platinum was studied in concentrated phosphoric acid containing different concentrations of water at room temperature. The results show that effect of bulk water on the rate electro-oxidation is highest at 0.60 V and decreases for increasing potentials. This was suggested as due to the increasing formation of oxygenated species on the electrode surface with potential, which in turn is more efficient than the increase of water content in the electrolyte. Altogether, these results were interpreted as an evidence of a Langmuir-Hinshelwood step involving oxygenated species as one of the adsorbed partners. (C) 2009 Elsevier B.V. All rights reserved.

Effects of polymer concentration and cationic surfactant on the morphology of electrospun polyacrylonitrile nanofibres

PAN nanofibres were prepared via an electrospinning process. The effect of polymer concentration on the fibre morphology was studied. At a very dilute solution, no fibres were obtained in the electrospinning process. As the concentration increased, the fibre morphology evolved from a beads-on-string structure to a uniform fibre structure with increasing fibre diameters. However, when the same electrospinning process was conducted with the addition of a cationic surfactant, the formation of disconnected beads was prevented, and the number of beads-on-string structures reduced significantly. In addition, the presence of cationic surfactant reduced the average diameter of the electrospun PAN nanofibres.

Socio-economic inequalities in women`s fruit and vegetable intakes: a multilevel study of individual, social and environmental mediators

Objective: This study employed a multilevel design to test the contribution of individual, social and environmental factors to mediating socio-economic status (SES) inequalities in fruit and vegetable consumption among women. Design: A cross-sectional survey was linked with objective environmental data. Setting: A community sample involving 45 neighbourhoods. Subjects: In total, 1347 women from 45 neighbourhoods provided survey data on their SES (highest education level), nutrition knowledge, health considerations related to food purchasing, and social support for healthy eating. These data were linked with objective environmental data on the density of supermarkets and fruit and vegetable outlets in local neighbourhoods. Results: Multilevel modelling showed that individual and social factors partly mediated, but did not completely explain, SES variations in fruit and vegetable consumption. Store density did not mediate the relationship of SES with fruit or vegetable consumption. Conclusions: Nutrition promotion interventions should focus on enhancing nutrition knowledge and health considerations underlying food purchasing in order to promote healthy eating, particularly among those who are socio-economically disadvantaged. Further investigation is required to identify additional potential mediators of SES–diet relationships, particularly at the environmental level.

Low birth weight in South Asian babies in Britain: time to reduce the inequalities

Babies born in Britain to women of South Asian ethnic origin are lighter on average than the offspring of women of European origin. The causes have been incompletely elucidated but nutritional factors, low socioeconomic status and maternal pre-pregnancy weight have been implicated. This health inequality has received little policy prioritization in Britain. As further research clarifies reasons for this differential, appropriately targeted preventive strategies need to be implemented.

A complex relationship among chemical concentration, detection threshold and suprathreshold intensity of bitter compounds

Detection thresholds and psychophysical curves were established for caffeine, quinine-HCl (QHCl), and propylthiouracil (PROP) in a sample of 33 subjects (28 female mean age 24 ± 4). The mean detection threshold (±standard error) for caffeine, QHCl, and PROP was 1.2 ± 0.12, 0.0083 ± 0.001, and 0.088 ± 0.07 mM, respectively. Pearson product–moment analysis revealed no significant correlations between detection thresholds of the compounds. Psychophysical curves were constructed for each bitter compound over 6 concentrations. There were significant correlations between incremental points of the individual psychophysical curves for QHCl and PROP. Regarding caffeine, there was a specific concentration (6 mM) below and above which the incremental steps in bitterness were correlated. Between compounds, analysis of psychophysical curves revealed no correlations with PROP, but there were significant correlations between the bitterness of caffeine and QHCl at higher concentrations on the psychophysical curve (P < 0.05). Correlation analysis of detection threshold and suprathreshold intensity within a compound revealed a significant correlation between PROP threshold and suprathreshold intensity (r = 0.46–0.4, P < 0.05), a significant negative correlation for QHCl (r = –0.33 to –0.4, P < 0.05), and no correlation for caffeine. The results suggest a complex relationship between chemical concentration, detection threshold, and suprathreshold intensity.

Personal, social and environmental determinants of educational inequalities in walking: a multilevel study

Objective: To investigate the contribution of personal, social and environmental factors to mediating socioeconomic (educational) inequalities in women’s leisure-time walking and walking for transport.
Methods: A community sample of 1282 women provided survey data on walking for leisure and transport; educational level; enjoyment of, and self-efficacy for, walking; physical activity barriers and intentions; social support for physical activity; sporting/recreational club membership; dog ownership; and perceived environmental aesthetics and safety. These data were linked with objective environmental data on the density of public open space and walking tracks in the women’s local neighbourhood, coastal proximity and street connectivity.
Results: Multilevel modelling showed that different personal, social and environmental factors were associated with walking for leisure and walking for transport. Variables from all three domains explained (mediated) educational inequalities in leisure-time walking, including neighbourhood walking tracks; coastal proximity; friends’ social support; dog ownership; self-efficacy, enjoyment and intentions. On the other hand, few of the variables examined explained educational variations in walking for transport, exceptions being neighbourhood, coastal proximity, street connectivity and social support from family.
Conclusions: Public health initiatives aimed at promoting, and reducing educational inequalities in, leisure-time walking should incorporate a focus on environmental strategies, such as advocating for neighbourhood walking tracks, as well as personal and social factors. Further investigation is required to better understand the pathways by which education might influence walking for transport.

lCT and educational (dis) advantage: families, computers and contemporary social and educational inequalities

Because access to new technologies is unequally distributed, there has been considerable debate about the growing gap between the so-called information-rich and information-poor. Such concerns have led to high-profile information technology policy initiatives in many countries. In Australia, in an attempt to 'redress the balance between the information rich and poor' by providing 'equal access to the World Wide Web' (Virtual Communities, 2002), the Australian Council of Trade Unions, Virtual Communities (a computer/software distributor) and Primus (an Internet provider) in late 1999 formed an alliance to offer relatively inexpensive computer and Internet access to union members in order to make 'technology affordable for all Australians' (Virtual Communities, 2002). In this paper, we examine four families, one of which had long-term Information and Communication Technologies (lCT) access, and three of which took advantage of the Virtual Communities offer to get home computer and Internet access for the first time. We examine their engagement with lCT and suggest that previously disadvantaged family members are not particularly advantaged by their access to lCT.

Equity-focused health impact assessment: a tool to assist policy makers in addressing health inequalities.

In Australasia (Australia and New Zealand) the use of health impact assessment (HIA) as a tool for improved policy development is comparatively new. The public health workforce do not routinely assess the potential health and equity impacts of proposed policies or programs. The Australasian Collaboration for Health Equity Impact Assessment was funded to develop a strategic framework for equity-focused HIA (EFHIA) with the intent of strengthening the ways in which equity is addressed in each step of HIA. The collaboration developed a draft framework for EFHIA that mirrored, but modified the commonly accepted steps of HIA; tested the draft framework in six different health service delivery settings; analysed the feedback about application of the draft EFHIA framework and modified it accordingly. The strategic framework shows promise in providing a systematic process for identifying potential differential health impacts and assessing the extent to which these are avoidable and unfair. This paper presents the EFHIA framework and discusses some of the issues that arose in the case study sites undertaking equity-focused HIA.

Socio-demographic inequalities in the diets of mid-aged Australian women

Objectives: This study reports on the distributions of food and nutrient intakes by socio-demographic factors for a large population sample of mid-aged Australian women participating in the Australian Longitudinal Study on Women's Health.
Design: This cross-sectional population-based study used the Cancer Council of Victoria food frequency questionnaires to derive estimates of food and nutrient intakes.
Setting: Nationwide community-based survey.
Subjects: A total of 10561 women aged 50-55 y, at the time of the survey in 2001.
Results: Analysis showed favourable patterns of food intake, with frequent consumption of many foods that are promoted as components of a healthy diet (eg, fresh fruit, leafy green and other vegetables, bread, cereals, milk and meat). Intakes of both foods and nutrients varied significantly across socio-demographic groups, with unmarried women, and women in 'labouring' occupations (eg, cleaner, factory worker, kitchenhand) having poorer nutrient intake.
Conclusions: Although many mid-aged women in this sample had generally healthful diets, women in certain socio-demographic groups (particularly unmarried women and those in labouring occupations) had nutrient intakes of concern. As well as helping to address the dearth of current data on dietary intakes in the Australian population, the results highlight the need for continued targeted public health strategies aimed at improving diet of women from the various socio-economic backgrounds.

The effects of exercise and adipose tissue lipolysis on plasma adiponectin concentration and adiponectin receptor expression in human skeletal muscle

Objective: It has been suggested that adiponectin regulates plasma free fatty acid (FFA) clearance by stimulating FFA uptake and/or oxidation in muscle. We aimed to determine changes in plasma adiponectin concentration and adiponectin receptor 1 and 2 mRNA expression in skeletal muscle during and after prolonged exercise under normal, fasting conditions (high FFA trial; HFA) and following pharmacological inhibition of adipose tissue lipolysis (low FFA trial; LFA). Furthermore, we aimed to detect and locate adiponectin in skeletal muscle tissue. Methods: Ten subjects performed two exercise trials (120 min at 50% VO2max). Indirect calorimetry was used to determine total fat oxidation rate. Plasma samples were collected at rest, during exercise and during post-exercise recovery to determine adiponectin, FFA and glycerol concentrations. Muscle biopsies were taken to determine adiponectin protein and adiponectin receptor 1 and 2 mRNA expression and to localise intramyocellular adiponectin. Results: Basal plasma adiponectin concentrations averaged 6.57±0.7 and 6.63±0.8 mg/l in the HFA and LFA trials respectively, and did not change significantly during or after exercise. In the LFA trial, plasma FFA concentrations and total fat oxidation rates were substantially reduced. However, plasma adiponectin and muscle adiponectin receptor 1 and 2 mRNA expression did not differ between trials. Immunohistochemical staining of muscle cross-sections showed the presence of adiponectin in the sarcolemma of individual muscle fibres and within the interfibrillar arterioles. Conclusion: Plasma adiponectin concentrations and adiponectin receptor 1 and 2 mRNA expression in muscle are not acutely regulated by changes in adipose tissue lipolysis and/or plasma FFA concentrations. Adiponectin is abundantly expressed in muscle, and, for the first time, it has been shown to be present in/on the sarcolemma of individual muscle fibres.

Use of in vitro critical inhibitory concentration, a novel approach to predict in vivo synergistic bactericidal effect of combined amikacin and piperacillin against pseudomonas aeruginosa in a systemic rat infection model

PURPOSE: This study was undertaken to explore the use of in vitro critical inhibitory concentration (CIC) as a surrogate marker relating the pharmacokinetic (PK) parameters to in vivo bactericidal synergistic effect [pharmacodynamic (PD)] of amikacin + piperacillin combination against Pseudomonas aeruginosa in a systemic rat infection model. METHODS: The in vitro antibacterial activities of amikacin and piperacillin, alone and in combinations at various ratios of the concentrations, were tested against a standard [5 x 10(5) colony-forming units (CFU)/ml] and a large (1.5 x 10(8) CFU/ml) inoculum of P. aeruginosa ATCC 9027 using a modified survival-time method. The CIC of each individual antibiotic for the different combinations was determined using a cup-plate method. In vivo studies were performed on Sprague-Dawley rats using a systemic model of infection with P. aeruginosa ATCC 9027. PK profiles and in vivo killing effects of the combination at different dosing ratios were studied. RESULTS: An inoculum effect was observed with the antibiotics studied. Synergy was seen against both the inocula at the following concentration ratios: 70% C(ami) + 30% C(pip) and 75% C(ami) + 25% C(pip), where C(ami) and C(pip) are the concentrations of amikacin and piperacillin to produce a 1000-fold decrease in bacterial population over 5 h, respectively. The CIC values determined corroborated with the order of in vitro bacterial killing observed for the antibiotic combinations. The dosing ratio of 12.6 mg/kg amikacin + 36 mg/kg piperacillin (a 70:30 ratio of the individual doses) exhibited the greatest killing in vivo when compared to the other ratios. The PK-PD relationships were described by simple, linear regression equations using the area under the in vivo killing curve as a PD marker and the AUCIC(ami)/CIC(ami) + AUCIC(pip)/CIC(pip), AUC(ami)/CIC(ami) + AUC(pip)/CIC(pip), C(max,ami)/CIC(ami) + C(max,pip)/CIC(pip), and AUCIC(ami)/MIC(ami) + AUCIC(pip)/MIC(pip) as PK markers for the amikacin + piperacillin combination. CONCLUSION: The combination of amikacin and piperacillin exhibited synergistic killing effect on P. aeruginosa that could be modeled using CIC as a surrogate marker relating the PK parameters to in vivo bactericidal effect.