The aim of this study was to evaluate the friction and wear behavior of ultra high molecular weight polyethylene (UHMWPE) against 3Y-TZP and a novel 3Y-TZP/niobium (Nb) biocomposite. The ceramic and the biocomposite materials were subjected to an accelerated aging process to evaluate the changes in the tribological behavior after this treatment. To carry out the tribological tests, a reciprocat...

Based on asymptotic considerations, this paper develops an improved approximate formula for estimating the relaxation function from the given compliance function of concrete, which is considered as aging, linearly viscoelastic material. Compared with the formula developed in 1979 by Ba zant and Kim, the new formula prevents any violation of the thermodynamic requirement of nonnegativeness of th...

Studies in the evolutionary biology of cancer research require good estimates of the intrinsic growth rate of the tumour coefficient. A Gompertzian model is a classical continuous model useful in describing population dynamics; in particular, it is a very efficient mathematical modelto describe tumour growth in humans and animals. The Gompertz survival model of a tumour growth is the interest o...

high variability in delivering the target torque is reported for friction-style mechanical torque limiting devices (f-s mtlds). the effect of aging (number of use) on the accuracy of these devices is not clear. the purpose of this study was to assess the effect of aging on the accuracy (±10% of the target torque) of f-s mtlds.fifteen new f-s mtlds and their appropriate drivers from three differ...

introduction: decrease in sleep quality is an age-related problem which appears in different features such as difficulty in sleeping, over sleeping and unusual behaviors during sleep. regarding the importance of sleep quality among older adults and also its effects on their quality of life and physical and mental status, the study was conducted to determine the status and quality of sleep in ol...

objective: oxidative stress as a consequence of aging can induce infertility in males. in this study, we have investigated the effects of aging on sperm parameters, intra-spermatic water soluble antioxidants, reactive oxygen species (ros), and in vitro blastocyst formation. methods: we chose 5 older nmri male mice (10-12 months) and 5 younger nmri male mice (2-3 months). sperm parameters, ros, ...

background the use of long-term care services has risen and this trend is expected to continue as the population reaches old age. objectives this study was performed to assess the caring conditions in nursing homes. patients and methods this study was conducted with a qualitative approach using conventional qualitative content analysis. the study was conducted on 23 iranian participants includi...

vitamin d deficiency is the most under-diagnosed medical condition in postmenopausal women. there are few epidemiologic studies on vitamin d status of postmenopausal women in iran. this study aimed to investigate the 25-hydroxyvitamin d levels in postmenopausal women living in tehran, capital of iran. in this cross sectional study, 110 women were selected via convenience sampling method from me...

the immune system of mammalian organisms undergoes alterations that may account for an increased susceptibility to certain infections, autoimmune diseases, or malignancies. well characterized are age related defect in t cell functions and cell mediated immunity. although it is well established that the functional properties of t cells decrease with age, its biochemical and molecular nature is p...