539 research outputs found
An observation of successful bat predation by Gabar Goshawk Micronisus gabar at Ndoto Mountains, Kenya
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Design and test of a magnetic thrust bearing
A magnetic thrust bearing can be employed to take thrust loads in rotating machinery. The design and construction of a prototype magnetic thrust bearing for a high load per weight application is described. The theory for the bearing is developed. Fixtures were designed and the bearing was tested for load capacity using a universal testing machine. Various shims were employed to have known gap thicknesses. A comparison of the theory and measured results is presented
Brominated Flame Retardants in the Environment: their Sources and Effects (A Review)
Brominated flame retardants (BFRs) are organic substances frequently used in many industries. The most important group within BFRs are polybrominated diphenyl ethers (PBDEs). Because they persist in the environment, accumulate in food chains and have toxic effects, they are a potential health risk both for animals and humans. Polybrominated diphenyl ethers may disrupt processes of hormonal regulation in living organisms by reducing thyroxine concentrations in the plasma of the exposed individuals. In vitro studies have demonstrated the ability of these substances to bind to estrogen and androgen receptors. Tests on rodents have also demonstrated neurotoxicity of some of the PBDEs. Although industrial use of PBDEs is now regulated to a large extent, PBDEs have already been detected in areas with no apparent industrial load, e.g. in Greenland. This article presents an overview of BFRs-related issues with a particular emphasis on PBDEs, describes toxic effects of those substances and their metabolism in living organisms, and discusses issues related to the incidence of PBDEs in the environment
Development and modeling the heat exchange element concepts of convection high temperature compressed air heater
Рассмотрен способ интенсификации теплообмена, при рекуперативном нагреве воздуха до температур порядка 800-1000°С. Проанализировано влияние на процесс теплообмена высоты и толщины продольного ребра, а так же их стоимостные показатели. Выбрана конструкция теплообменного элемента для дальнейшей проработки. Проведено численное моделирование выбранной конструкции в пакете CFD.Тhe method heat transfer enhancement was considered in regenerative air heating to temperatures of about 800-1000 ° C. Impact the fins height and longitudinal thickness on heat transfer were analyzed, as well as their cost parameters were analyzed. The design of the heat exchanger element has been selected for further development. Numerical simulation of the chosen design conducted in CFD.Исследование выполнено в Уральском федеральном университете за счет гранта Российского научного фонда (проект №14-19-00524)
Is Poor Sleep Quality Associated With Greater Disability in Patients With Multiple Sclerosis?
Poor sleep is a serious burden for patients with multiple sclerosis (MS). The aim of this study is to assess whether the association between sleep quality and disability in MS patients is direct or mediated by depression, pain, and fatigue. We collected data from 152 patients with MS who filled out the Pittsburgh Sleep Quality Index, the Hospital Anxiety and Depression Scale, the Multidimensional Fatigue Inventory and one item of the Short Form-36 regarding pain. The relationship between poor sleep and disability was found to be indirect, mediated by depression (p <0.05), pain (p <0.001) and physical fatigue (p <0.01). Treatment of sleep disturbances may have beneficial effects beyond improving sleep. It may reduce depression, pain, and physical fatigue, which in turn may lessen disability.</p
Effects of Metazachlor on Vitellogenin Induction in Zebrafish (Danio rerio)
The influence of metazachlor on vitellogenesis in juvenile (20 days old) zebrafish (Danio rerio) was investigated after ambient water exposure to concentrations of 0.1, 1.0 and 5.0 mg l-1 of the chloroacetanilide herbicide Butisan 400 SC containing approximately 35.6% (w/w) metazachlor. After 20 days of exposure, vitellogenin concentrations in whole-body homogenates of the fish were measured by direct sandwich ELISA. The results were compared to vitellogenin concentrations in fish from both negative (no exposure) and positive (exposed to natural oestrogen 17β-oestradiol) control groups. Exposure to Butisan 400 SC at a concentration of 5.0 mg l-1 induced vitellogenin synthesis significantly compared to the control fish (p < 0.05). The oestrogenic effect of 17β-oestradiol was confirmed
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