Nonlinear Vibrational Analysis of Nanobeams Embedded in an Elastic Medium including Surface Stress Effects

Due to size-dependent behavior of nanostructures, the classical continuum models are not applicable for the analyses at this submicron size. Surface stress effect is one of the most important matters which make the nanoscale structures have different properties compared to the conventional structures due to high surface to volume ratio. In the present study, nonlinear free vibrational characteristics of embedded nanobeams are investigated including surface stress effects. To this end, a thin surface layer is assumed on the upper and lower surfaces of the cross section to separate the surface and bulk of nanobeams with their own different material properties. Based on harmonic balance method, closed-form analytical solution is conducted for nonlinear vibrations to obtain natural frequencies of embedded nanobeams with and without considerations of surface elasticity and residual surface tension effects corresponding to the various values of nondimensional amplitude, elastic foundation modulus, and geometrical variables of the system. Selected numerical results are given to indicate the influence of each one in detail

The potential of small mountain river systems for paleoenvironmental reconstructions in drylands - an example from the Binaloud Mountains in Northeastern Iran

Fluvial sediments are valuable paleoenvironmental archives of the Quaternary. Since besides environmental factors they are also affected by local tectonics or intrinsic processes, large instead of small catchments should be studied. In drylands covering ca. 45% of the global terrestrial surface large river systems are generally missing, and most river systems are small rivers originating from mountain ranges. Their sediments are potentially interesting paleoenvironmental archives, but are often affected by intensive tectonics. During this study, to obtain a robust regional paleoenvironmental signal a small river system in the southwestern Binaloud Mountains in semi-arid NE Iran was exemplarily studied with a combined approach that encompassed both alluvial fan and catchment. By using geomorphological mapping and numerical dating, fluvial aggradation followed by incision was independently identified in larger areas or in different parts of the river system ca. 95–88 ka, 40 ka, 20 ka, around/after the Pleistocene/Holocene transition and possibly ca. 2.6 ka. These could be linked with regional and over-regional paleoenvironmental data. Furthermore, large boulders on the alluvial fan suggest anthropogenic destabilisation of the catchment during the last decades. Despite strong local tectonics the fluvial dynamics was mostly controlled by paleoenvironmental changes and human activity. This indicates that despite their small size, such river systems form valuable paleoenvironmental archives in drylands where other archive types are largely missing

IMPACT OF WATER RADIOLYSIS ON URANIUM DIOXIDE CORROSION

International audienc

Investigating the Effect of Foliar Applied Proline on the Photosynthetic Pigments Content and Osmolytes of Pistachio Rootstock UCB1 under Water Stress Conditions

Introduction  UCB-1 hybrid rootstock is propagated from the seed of a controlled cross between a P. atlantica female and a P. integerrima male. Clonal propagation of this rootstock is also necessary since it produces identical genotypes. UCB1 has recently been introduced in Iran. However, little research has been done on this subject. Water stress is one of the most important environmental stresses and occurs for several reasons, including low rainfall, high and low temperatures, salinity, and high intensity of light, among others. Drought stress is a multidimensional stress and causes changes in the physiological, morphological, biochemical, and molecular traits in plants. Proline is also found widely in plants and accumulates in large quantities in response to environmental stresses such as drought. It is the essential amino acids that accumulate in different tissues of the plant, especially in the leaves through the effect of water stress, and that the accumulation of it has a function in the regulation of osmosis in the cell as the proline is increased in the cytoplasm to counterbalance effort osmosis cell sap. Proline is an indicator of water stress tolerance and its increase in the leaf proof that the plant suffered drought stress, also is the way the plant tolerance to drought stress.   Materials and Methods A pot experiment was conducted, to investigate the effectiveness of foliar applied proline in mitigating the concurrent effects of drought stresses on UCB1 rootstock, at greenhouse of Faculty of Agriculture, University of Shahrekord. Experiment was carried out in a completely randomized design with split arrangement having three replications. Chl. and carotenoid contents were determined according to Lichtenthaler (1987). Leaf discs were obtained from expanded leaves of each pot in the morning. The leaf discs were weighed immediately to obtain the fresh weight (FW), and submerged in distilled water for 4 h at 4◦C in dark condition and then weighed to prepare turgor weight (TW). The leaves were dried in a forced-air oven at 70◦C for 24 h, and the dry weight (DW) was recorded. The RWC of samples was calculated using the following equation (Bastam et al., 2012): RWC = [(FW–DW)/(TW–DW)] × 100 Levels of glycine betaine were quantified as described previously by Arakawa et al. (1990). To determine the free-proline concentration, leaves were homogenized in 5 ml of ethanol at 95%. Proline concentration was calculated with a standard curve and expressed as µg g−1fresh mass (Paquin and Lechasseur, 1979).   Results and Discussion The UCB1 proximate analysis in the present study depicted that imposition of drought stress increased the leaf and root proline content and electrolyte leakage. Exogenous application of proline as foliar spray significantly increased the moisture content of leaf and root, RWC, Chl a and total chlorophyll. Exogenous proline application upregulated leaf and root proline contents and decreased the lipid peroxidation (decrease electrolyte leakage), resulting into improvement in chlorophyll contents. 150 mg. l-1 proline application gave maximum alleviation against stress. Numerous reports depict that the exogenous application of proline as a foliar spray can play an important role in enhancing plant tolerance against drought stress, and our results are consistent with them. This ameliorating effect of exogenously applied proline can take the form of osmoprotection, cryoprotection, or protection against reactive oxygen species.For example, in various plant species growing under stress conditions, exogenously supplied proline provided osmoprotection and facilitated plant growth. Normally, proline accumulation in plants, is in response to drought or salinity stress occurs in the cytosol where it contributes substantially to the cytoplasmic osmotic adjustment. It actively takes part in plant osmotic adjustment under stressful environmental conditions. In addition to its role as an osmolyte for osmotic adjustment, it actively takes part to stabilize subcellular structures, biological membranes, proteins, and scavenge free radicals. It also plays a vital role in buffering cellular redox potential under stressful environmental conditions.   Conclusion  In summary, our results showed that, drought induces a decrease in moisture content, RWC, T Chl and carotenoids and an increase in some osmoregulators (proline, glycine betaine, TSC). The most favorable treatment was 150 mg.l-1 proline foliar spray. 150 mg.l-1 proline application gave maximum alleviation against stress. Foliar application increased the moisture content of leaf and root, as well as increased the Chl a, total, RWC and proline content of leaf and root. It can be suggested that the foliar application of proline (150 mg L-1) used as a plants defense factor against drought stress conditions

Auditory memory function in expert chess players

Background: Chess is a game that involves many aspects of high level cognition such as memory, attention, focus and problem solving. Long term practice of chess can improve cognition performances and behavioral skills. Auditory memory, as a kind of memory, can be influenced by strengthening processes following long term chess playing like other behavioral skills because of common processing pathways in the brain. The purpose of this study was to evaluate the auditory memory function of expert chess players using the Persian version of dichotic auditory-verbal memory test. Methods: The Persian version of dichotic auditory-verbal memory test was performed for 30 expert chess players aged 20-35 years and 30 non chess players who were matched by different conditions; the participants in both groups were randomly selected. The performance of the two groups was compared by independent samples t-test using SPSS version 21. Results: The mean score of dichotic auditory-verbal memory test between the two groups, expert chess players and non-chess players, revealed a significant difference (p = 0.001). The difference between the ears scores for expert chess players (p = 0.023) and non-chess players (p = 0.013) was significant. Gender had no effect on the test results. Conclusion: Auditory memory function in expert chess players was significantly better compared to non-chess players. It seems that increased auditory memory function is related to strengthening cognitive performances due to playing chess for a long time

Lymphangioma of the thoracic spine with epidural compression: A case report

Lymphangiomas are benign lesions consisting of abnormal proliferations of lymphaticvessels. Lymphangiomas associatedwith bone involvement, particularly in vertebral bodies, accompanied by cord compression, are extremely rare, and our literature review yielded only a few relevant reports. We describe a 61-year-old man presenting with progressive paraparesis and sphincter disturbance of 5 months� duration. Magnetic resonance imaging (MRI) revealed an enhancing T8 vertebral body involvement as well as a homogeneously enhancing posterior epidural mass at the T7�T8 level, with severe cord compression and cerebrospinal fluid (CSF) blockade. The patient underwent surgery via T7�T8 laminectomy, and after the removal of the epidural mass, the surgical procedure was stopped due to severe bleeding. Histopathologic examination reported a lymphangioma. After 10 days, the patient was able to walk. In the sixth postoperative month, MRI showed complete relief of the mass effect. The wide spectrum of the preoperative differential diagnosis of lymphangiomas renders a definite preoperative diagnosis impossible; therefore, histopathologic examination is the sole definite route for their diagnosis. In case of the solitary lymphangiomas of the spine with epidural compression, preoperative angiography and embolization should be considered to reduce intraoperative bleeding and enhance the chance of total resection and total surgical resection should be performed to decrease the likelihood of recurrence. © 2019, Shiraz University of Medical Sciences. All rights reserved

Disabilities and Activities of Daily Living Among Veterans With Old Hip Disarticulation and Transpelvic Amputation

Background: The Iran-Iraq imposed war lasted eight years and was one of the longest wars of the last century. Twenty-three years have passed since the war ended, but little has been discussed about the long-term results of war amputations in the literature. Objectives: In this long-term study, we have evaluated the activities of daily living among veterans with hip or hemipelvis amputations. Patients and Methods: A cross-sectional study was performed on Iran-Iraq war veterans with hip or hemipelvis amputations in Iran. Eighty-four (96.5%) veterans out of 87 registered veterans with hip or hemipelvis amputations participated in the study. The degree of independence for activities of daily living (ADL) was assessed by the Barthel index. The degree of independence for instrumental activities of daily living (IADL) was assessed by the Lawton-Brody scale. Results: The average follow-up time was 26.6 ± 3.7 years. The average age of veterans was 44.1±7 years old. Of 84 amputees, 57 (67.85%) had limitations in at least one domain of the ADL. The most common single item that affected the patients was ascending and descending stairs seen in 45 (78.9%) veterans, followed by eating seen in 4 (7.01%) veterans. In addition, 70 (83.33%) had limitations in at least one domain of the IADL. The most common single item that affected the veterans was shopping seen in 56 (80%), followed by responsibility for own medications seen in 13 (18.57%) veterans. Spearman correlation coefficient of the sum scores of ADL and IADL showed an intermediate to strong correlation (r = 0.58). Conclusions: Increasing dependency in ADL is accompanied by increasing dependency in IADL. In the past, the duty of health care providers was saving the life of veterans due to injuries while at present, because these injuries occurred in young and healthy individuals, the need for increased function is being highlighted