963 resultados para Physical and chemical parameters


Relevância:

100.00% 100.00%

Publicador:

Resumo:

Galvanneal steel is considered to be better for automotive applications than its counterpart, galvanized steel, mainly because of its superior coating and surface properties. Galvanneal steel is produced by hot dipping sheet steel in a bath of molten zinc with small, controlled, levels of aluminium, followed by annealing which creates a Fe-Zn intermetallic layer. This intermetallic layer of the coating improves spot weldability and improves subsequent paint appearance. However, if the microstructure of the coating is not properly controlled and forming parameters are not properly selected, wear of the coating could occur during stamping. Frictional sliding of the sheet between the tool surfaces results in considerable amount of coating loss. An Interstitial Free steel with a Galvanneal coating of nominally 60g/m2 was used for the laboratory experiments. Flat Face Friction (FFF) tests were performed with different forming conditions and lubricants to simulate the frictional sliding in stamping. Glow-Discharge Optical Emission Spectrometry (DG-OES) was used to measure the change in the coating thickness during sliding. Optical microscopy was considered for imaging the surfaces as well as an optical method to compare the changes in the coating thickness during the forming. The change to the Galvanneal coating thickness was found to be a function of forming parameters.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The Western Treatment Plant, a major sewage treatment plant west of Melbourne, Australia, is widely regarded as a significant conservation site for waterbirds. But experiences from various parts of the world suggest that sewage can also be hazardous to waterbirds, and has probably been responsible for mass-kill events. The intent of this contribution is to raise awareness about the potential for adverse impacts of sewage treatment plants on waterbirds, and to stimulate debate on the issue, with the ultimate objective of developing appropriate management strategies to mitigate the risk of mass kills.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Developing a lean muscular figure for the purposes of sports and/or appearance has become a central issue for males. Concern has been raised because the desire to develop such a body build may lead to the adoption of numerous health-threatening behaviors. Consequently, this review presents a comprehensive analysis of the physical and psychological consequences that result from the use of steroids (legal and illegal), ephedrine, and deleterious dieting strategies specific to males. Putative risk factors for these behaviors will be identified, and the clinical disorder associated with the extreme abuse of these behaviors, muscle dysmorphia, will be examined.


Relevância:

100.00% 100.00%

Publicador:

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Background: Studies have shown associations between health indices and access to “green” environments but the underlying mechanisms of this association are not clear.

Objectives: To examine associations of perceived neighbourhood “greenness” with perceived physical and mental health and to investigate whether walking and social factors account for the relationships.

Methods: A mailed survey collected the following data from adults (n  =  1895) in Adelaide, Australia: physical and mental health scores (12-item short-form health survey); perceived neighbourhood greenness; walking for recreation and for transport; social coherence; local social interaction and sociodemographic variables.

Results: After adjusting for sociodemographic variables, those who perceived their neighbourhood as highly green had 1.37 and 1.60 times higher odds of better physical and mental health, respectively, compared with those who perceived the lowest greenness. Perceived greenness was also correlated with recreational walking and social factors. When walking for recreation and social factors were added to the regression models, recreational walking was a significant predictor of physical health; however, the association between greenness and physical health became non-significant. Recreational walking and social coherence were associated with mental health and the relationship between greenness and mental health remained significant.

Conclusions: Perceived neighbourhood greenness was more strongly associated with mental health than it was with physical health. Recreational walking seemed to explain the link between greenness and physical health, whereas the relationship between greenness and mental health was only partly accounted for by recreational walking and social coherence. The restorative effects of natural environments may be involved in the residual association of this latter relationship.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Objective
The role local neighbourhood environments play in influencing purpose-specific walking behaviors has not been well-explored in prospective studies. This study aimed to cross-sectionally and prospectively examine whether local physical and social environments were associated with mothers' walking for leisure and for transport.

Methods
In 2004, 357 mothers from Melbourne, Australia, provided information on their local physical and social neighbourhood environments, and in 2004 and 2006 reported weekly time spent walking for leisure and for transport. Environmental predictors of high levels of walking and increases in walking were examined using log binomial regression.

Results
Public transport accessibility and trusting many people in the neighbourhood were predictive of increases in walking for leisure, while connectivity, pedestrian crossings, a local traffic speed were predictive of increases in transport-related walking. Satisfaction with local facilities was associated with increasing both types of walking, and the social environment was important for maintaining high levels of both leisure- and transport-related walking.

Conclusion
The findings provide evidence of a longitudinal relationship between physical and social environments and walking behaviors amongst mothers. Enhancing satisfaction with local facilities and giving consideration to ‘walkability’, safety and public transport accessibility during environment planning processes may help mothers to increase walking.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This work investigated the potential of improving flexural properties of natural fiber (jute) reinforced biocomposites by atmospheric pressure helium plasma treatment. Composites were made by the use of combined hand lay-up and vacuum bagging technique followed by newly developed Australia patented QuickstepTM curing. The physical properties of helium plasma modified fibers were investigated by means of wettability time, coefficient of friction (COF), atomic force microscopy (AFM) and chemical nature of the surface with ATR-FTIR and XPS. There was found a logical correlation between physical and chemical characteristics of the surface of fiber with the fracture mechanical behavior of their resulting biocomposites. In addition, the use of helium atmospheric plasma treatment prior to QuickstepTM process has proved to be a potential way to positively alter the fracture-mechanical behavior of biocomposites. This study will lead to new commercial applications of natural fiber jute for the composite industry that go beyond wrapping and packaging.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Research has addressed the consequences of being a victim of physical and relational aggression but less so the consequences of being an aggressor during adolescence. Consequently, relatively little is known about the extent to which aggression in early adolescence increases the risk of later aggression and other psychosocial problems. This study involves a representative sample of seventh- and ninth-grade students from Washington State ( N = 1,942). Students were surveyed on recruitment and then again 1 and 2 years later to learn about ongoing behavior problems, substance use, depression, and self-harm behaviors. Surveys also included measures of several hypothesized promotive factors: attachment to family, school commitment, and academic achievement. Findings suggest that being physically and/or relationally aggressive in grades 7 to 9 increases the risk of aggression and possibly other problem behaviors after accounting for age, gender, race, and a prior measure of each outcome. Independent promotive effects were observed in most analyses, although family attachment appeared a less robust predictor overall. Implications for prevention include acting on the behavior itself and enhancing promotive influences to lessen the risk of agression and other related problems.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A newly isolated strain of Kluyveromyces marxianus YS-1 was used for the production of extra cellular inulinase in a medium containing inulin, meat extract, CaCl2 and sodium dodecyl sulphate (SDS). Fermentation medium pH 6.5, cultivation temperature 30 °C and 5% (v/v) inoculum of 12 h-old culture were optimal for enzyme production (30.8 IU/ml) with a fermentation time of 72 h at shake flask level. Raw inulin (2%, w/v) extracted from dahlia tubers by processing at 15 kg/cm2 for 10 min was optimum for bioreactor studies. Maximum enzyme production (55.4 IU/ml) was obtained at an agitation rate of 200 rpm and aeration of 0.75 vvm in a stirred tank reactor with a fermentation time of 60 h.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Depression is a significant public health issue among Australian adolescents. A number of family, school and community level factors have been identified as important determinants of adolescent's health and well-being, including depression. This study examines associations between measures of the social and physical environment and adolescent mental health, specifically depressive symptomotology using data from the Healthy Neighbourhoods study, a large observational study carried out in 231 Australian schools stratified by socioeconomic quartiles and urban/non-urban geography, which focuses on adolescent health and well-being. Participants were 8256 year 6 and 8
students (48% male), aged 11-16 years (M = 11.6, SD = 0.8 years) from schools across Victoria,Queensland and Western Australia who completed a comprehensive on-line survey. Data collected included the Short Mood and Feeling Questionnaire (SMFQL a tool for assessing depressive symptomotology in adolescents. Results showed that the mean total depression score (possible range 0-26 with total scores;:: 8 used as the cutoff for depression symptomotology) was 6.4 (SD = 5.9), with scores for females (M = 6.8, SD = 6.3) higher than those for males (M = 5.9, SD = 5.5), and scores for year 8 students (M = 6.7,SD = 6.1) higher than those for year 6 students (M = 6.2, SD = 5.8) (p < .001). Greater access to sporting and play equipment, local parks, and more functional neighbourhoods for walking and jogging reduced the odds for depressive symptomotology (p < .05L while increased levels of abandoned homes, and higher levels of fighting within the neighbourhood, and fewer scout/guide clubs, local teams to play sport, and adults in the neighbourhood to talk with, as well as reduced neighbourhood safety increased the odds for depressive symptomotology (p < .05). These findings support the important role of physical and social environments in influencing adolescent health and well-being. Modifications to particular aspects of these environments at the community level may assist in providing adolescents some protection from depression.