50 resultados para Physical and chemical parameters


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It has been hypothesized that the brain categorizes stressors and utilizes neural response pathways that vary in accordance with the assigned category. If this is true, stressors should elicit patterns of neuronal activation within the brain that are category-specific. Data from previous immediate–early gene expression mapping studies have hinted that this is the case, but interstudy differences in methodology render conclusions tenuous. In the present study, immunolabelling for the expression of c-fos was used as a marker of neuronal activity elicited in the rat brain by haemorrhage, immune challenge, noise, restraint and forced swim. All stressors elicited c-fos expression in 25–30% of hypothalamic paraventricular nucleus corticotrophin-releasing-factor cells, suggesting that these stimuli were of comparable strength, at least with regard to their ability to activate the hypothalamic–pituitary–adrenal axis. In the amygdala, haemorrhage and immune challenge both elicited c-fos expression in a large number of neurons in the central nucleus of the amygdala, whereas noise, restraint and forced swim primarily elicited recruitment of cells within the medial nucleus of the amygdala. In the medulla, all stressors recruited similar numbers of noradrenergic (A1 and A2) and adrenergic (C1 and C2) cells. However, haemorrhage and immune challenge elicited c-fos expression in subpopulations of A1 and A2 noradrenergic cells that were significantly more rostral than those recruited by noise, restraint or forced swim. The present data support the suggestion that the brain recognizes at least two major categories of stressor, which we have referred to as ‘physicaland ‘psychological’. Moreover, the present data suggest that the neural activation footprint that is left in the brain by stressors can be used to determine the category to which they have been assigned by the brain.

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Body dissatisfaction is often associated with negative psychological functioning, such as depression, and maladaptive behaviors, such as unhealthy eating and extreme weight loss behaviors, which have serious negative implications for women’s health and well-being, and potentially also for the unborn fetus during pregnancy. This article summarizes contemporary research in the area of body image during pregnancy, showing the development of knowledge in this area with increasing research interest in this topic in more recent times.

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Aluminum nitride (AƖN) nanostructures have shown novel physical and chemical properties that are essential for technological applications. We report a vapor-solid growth of novel three-dimensional (3D) A1N urchin-like nanostmcture in DC arc plasma via the direct reaction between Al vapor and N2 gas without any catalyst or template. The as-prepared 3D A1N nanostructures which have urchin-like shapes consist of numerous microdaggers with sharp tips and lengths of up to several micrometers and widths of 0.5-2 µm. A growth mechanism of A1N nanostructures with urchin shapes was suggested and explained in detail. The optical properties of the AƖN nanostructures with urchin shapes were also studied with photoluminescence spectrum, which reveals a broad emission, suggesting potential applications in electronic and optoelectronic nanodevices.

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C1 and phenyl-type stationary phases were assessed in terms of their environmental impact on separations using as test solutes polycyclic aromatic hydrocarbons. Methanol (MeOH) and acetonitrile (ACN) mobile-phase gradients were employed. These stationary phases were examined to determine if different physical and chemical properties possessed by these surfaces decreased the organic solvent consumption, and yet maintained peak capacity. The cumulative energy demand (CED) was used to gauge the environmental impact of the separations. The separation of the polycyclic aromatic hydrocarbon test mixture using current methodologies (i.e. a C18/ACN combination) had a CED of 1.13 MJ-eq, and a peak capacity of 27 peaks (resolving 7 of 12 peak pairs with Rs>1). In comparison, a butyl phenyl stationary phase with a methanol mobile phase had a peak capacity of 26, but with a CED of 0.670 MJ-eq. Monolithic columns containing C18 and C1 phases were also tested. A monolithic C18 column with MeOH had the lowest CED at 0.675 MJ-eq, a peak capacity of 28 peaks and good resolving power (resolving ten peak pairs with Rs>1), suggesting that this is a viable option with respect to reducing environmental impact for these types of analyses.

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Currently there is a dearth of research into Australian Indigenous knowledge and their understanding of climate change especially in regard to how it fits into their world view. Recent discussions by the National Climate Change Adaptation Research facility (NCCARF) have highlighted this deficiency but also the need to source relevant research projects that may address this knowledge and perspective, and enable the incorporation of Traditional ecological Knowledge into the planning climate change adaptions strategies in the Port Phillip Bay region thereby increasing their engagement in this discussion. Within this context, this paper examines the use and understanding of landscape, both urban and regional, surrounding Port Phillip Bay and the risks and opportunities climate change adaptation brings to the local Indigenous communities. It synthesises focused interviews with the (Wurundjeri (Yarra Valley), Wathaurong Geelong-Bellarine Peninsular) & Boon Wurrung (Mornington Peninsula)) to elicit a contemporary and local response to issues raised by NCCARF but importantly to articulate a possible Indigenous position about the formation, change and direction that Port Phillip Bay and its environs should take from their perspectives. Research draws upon how these communities have adapted to climate change physically, mentally and spiritually over their long habitation of a shared geological asset and their perceptions of climate change in respect to forecasting and adapting to climate change for this century. The project looks to uncover a longitudinal perspective of change and adaptation focused upon Indigenous views of ‘country’ and traditional custodial obligations to ‘country’ including accumulated cultural and environmental histories.

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In this study, shell powder was modified by sodium stearate surface modifier for improving the compatibility of SP with polymer materials. The surface modifiers influence on the physical and chemical properties of SP were studied by scanning electron microscope(SEM), fourier infrared spectrum(FT-IR), surface contact angle meter, XRD diffraction analysis meter and other modern instruments and analysis method. The results showed that the surface modifier was successfully coupled to the shell powder surface. After surface modifier modification, the interfacial compatibility of the shell powder with polymer materials was effectively improved. The contact angle of shell powder surface increased from 73.5 ° to 110.8 °, along with the dosage of sodium stearate surface modifier was 4.0%. All results suggested that modified shell powder is promising for using as a reinforcement filler in polymer materials. © (2014) Trans Tech Publications, Switzerland.

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A partial latent structural regression analysis was used to evaluate the role of coping resources, depression, diet and exercise on mental and physical health status. The sample consisted of 113 participants (59 females and 54 males) with a mean age of 59.38 years (SD = 10.52). Coping resources, depression and exercise explained 52 and 26% of the variance in mental and physical health status, respectively. Fewer coping resources predicted higher levels of depression and both predicted worse mental health. Only higher levels of depression predicted worse physical health status. There were also significant indirect effects of coping on mental and physical health status through depression. The development of cognitive, social and emotional coping strategies is important for managing depression and supporting positive mental health. These results highlight the important role of health psychologists in the care of individuals with chronic illness. Additionally, the management of depression is important in maintaining positive physical health.

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Molybdenum disulfide (MoS2) nanosheets have unique physical and chemical properties, which make it a perfect candidate for next generation electronic and energy storage applications. Herein, we show the successful synthesis of nitrogen-doped MoS2 nanosheets by a simple, effective and large-scale approach. MoS2 nanosheets synthesised by this method show a porous structure formed by curled and overlapped nanosheets with well-defined edges. Analysis of the nanosheets shows that they have an enlarged interlayer distance and high specific surface area. X-ray photoelectron spectroscopy analysis shows the nanosheets have Mo-N bond indicating successful nitrogen doping. The nitrogen content of the product can be modulated by adjusting the ratio of starting materials easily within the range from ca. 5.8 to 7.6 at%.

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Occupational stress is common among nurses. Two factors that may influence stress levels are diet and physical activity. The purpose of this study was to investigate the diets and physical activity levels of nurses and to quantify the relationships between these behaviours and anxiety, depressed mood, stress, and burnout. Nurses (N = 52) from one regional hospital completed a survey assessing physical activity, nutrition, and psychological functioning. Almost two-thirds (65%) of participants had met recommended levels of both moderate and vigorous physical activity in the week prior. Participants met recommended levels for fruit, but not vegetable, consumption. Burnout and stress levels were close to norms for physicians and nurses. Scores for depressed mood, anxiety, and stress symptoms were within one standard deviation of norms for the Australian adult population. Several moderately sized correlations were found between the psychological constructs measured and both physical activity and nutrition. Although most of the participants were physically active and seemed to be consuming nutritious diets, some nurses may need encouragement to adopt similarly healthy behaviours.