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Objectives: Social participation is an important aspect of health in ageing. It is also a part of life and a key element in function that improves physical and psychological health in the elderly. Using assistive mobility devices may influence social participation in this population. Current study aimed to compare social participation in older adults who use assistive mobility devices with those who do not use assistive devices in Tehran. Methods & Materials: In this cross-sectional study, older adults with and without assistive mobility devices were comprised in their social participation. Seventy-nine old age adults (39 women and 40 men) who were 60 years or older were recruited using convenience sampling method. They completed life habit, mini mental state and demographic questionnaires. For analyzing continuous data with normal distribution, t test and ANOVA were used, while Kruskal-Wallis and Mann-Whitney tests were used for categorical variables or those with non-normal distribution. Results: The finding indicates that older adults with assistive mobility devices engage less in social participation than those who do not use these devices (P<0.05). Older adults in age group of 60-74 years had higher social participation in comparison with those in 75-89 age group (P<0.05). There was no significant differences between male and females, and single older adults and married ones in their social participation. Conclusion: Type of assistive device affects social participation in older adults. The results suggest that older adults with higher physical ability have higher social participation. Older adults who use assistive devices face with more limitations to participate socially in their community. It is necessary for rehabilitation team to pay attention in improving social participation of older adults.

Polymer/clay nanocomposites are considered as a new subject of research in Iran and the world. Addition of a minimum amount of clay (2-5wt%) can improve the mechanical properties, enhance barrier properties and reduce flammability dramatically. Polystyrene (PS) exhibits high strength, high modulus and excellent dimensional stability, but it has poor ductility, elongation, and flexural modulus. By incorporating clay into polystyrene these properties can be improved. In this study preparation of polystyrene/clay nanocomposite, effects of different types of clays (Cloisite 10A andNanomer I.30TC) and maleic anhydride modified polystyrene on mechanical properties of the prepared polystyrene/clay nanocomposites were evaluated. Samples were prepared by a twin screw extruder. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques were employed to evaluate the extent of intercalation and exfoliation of silicate layers in the nanocomposites. Mechanical tests show that by addition of clay and maleic anhydride modified polystyrene the flexural modulus (~30%) and elongation-at-break (~40%) of prepared nanocomposites have been improved. XRD and TEM results show that nanocomposite have an intercalated structure with ability to change to further exfoliation structure.

The high costs of experimental works on the nanocomposites can be reduced through implementation of analytical and numerical studies. To study the effect of impact energy on the nanocomposites, a nanocomposite composedof polyurethane and clay nanoparticles is selected as a case study. The finite element modeling is carried out using the ANSYS software, and the impact analysis is performed using LSDYNA. Three distinct regions: namely the polymer, the clay particles, and the interface are considered in the modeling. Subsequently, the effects of staggering factor, vertical distance between nanoparticles, aspect ratio, and volume fraction of clay nanoparticles on the reaction of the nanocomposite to the impact forces are investigated. The magnitude of the displacement of the specimen and the maximum force at the contact point are important parameters in impact analysis. In order to study the effect of structural parameters, two different impact velocities are considered, and for each 160 finite element modelings are performed. In each case, the effective parameters together with their limitations are considered. Different graphs are presented and analyzed for the effect of every structural parameter on the impact. The results of this study show that for a nanocomposite of aspect ratio equal 100, staggering factor of 0.5, and exfoliation factor of 0.51, the volume fraction of the clay nanoparticles is the range of 1.5 to 3 percent which can be considered opti-mum as far as the effect of impact forces are concerned.

Monogenic basaltic cinder cones and lava flows from west of Khash are part of volcanic arc of northern Makran, formed as a result of subduction of Oman oceanic lithosphere beneath the Eurasian plate. The basalts belong to medium-K calc-alkaline series as they contain high Al2O3 (16.5- 19.04 wt. %) and CaO (8.4- 12.0 wt. %) and moderate amounts of K2O (0.5- 1.1 wt. %). They share arc geochemical features such as high LILE/HFSE ([Rb/Zr]N-MORB up to 19) LILE/LREE ([Ba/La]N-MORB up to 4.86) and LREE/HREE ([La/Yb]N-MORB up to 10), and depletion of Ta, Nb, Zr, and Ti relative to N-MORB. Partial melting models indicate that near-primary basalts were derived from an enriched source type mantle wedge peridotite after low to medium degrees (2-10%) of partial melting. This source peridotite was enriched in LREE and LILE, by subduction derived fluids in the supra-subduction zone. Negative correlation of Th/La vs. Sm/La, and relationships between Pb/Ce and Th/Nb values of the studied basalts which are between two end compositions of global subducting sediment (GLOSS) and N-MORB are indicative of significant contribution of subducting sediments to the genesis of the basaltic rocks. Estimates made using binary mixing model are indicative of about 16% of sediment participation in the magma genesis. Low Pb/Ce ratio (1.6 - 11.1), compared to OIB (>20) may be a signature of participation of fluids resulted from dehydration of the subducting slab

The effect of microwave thermal treatment on mechanical properties of composites made from MDF dust-polypropylene was investigated. In this regard, nanoclay (Cloisite 15A) was added in three different (2, 4 and 6 %wt) levels into the composites. Furthermore, polypropylene (PP) was used as a matrix material and maleic anhydride-grafted polypropylene (MAPP) was used as coupling agent at 4%wt. The medium density fibreboard (MDF) dust was used as lignocellulosic material in the present study. Test samples were made, using extrusion process (twin screw), as granules. Then, samples with dimensions 30×20×1 cm were prepared with 1 g/cm3 nominal density for the polymer composites using hot pressing method. The bending strength and impact strength were measured according to the technical specifications CEN/TS15534:2007 and D-4495 regulation of ASTM standard, respectively. Field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) techniques were employed to evaluate the extent of intercalation and exfoliation of silicate layers in the nanocomposites. Finally, the mechanical tests of flexural strength, flexural modulus and impact strength were performed on the samples. The results showed that the highest flexural strength, flexural modulus and impact strength were obtained at level 2 wt% nanoclay particles. The mechanical strength of the samples that were treated by microwave radiation was the highest. Also, X-ray diffraction studies showed increases in the interlayer spacing of silicate layers and intercalation of polymer chains between the clay layers. Scanning electron microscopy results showed that in the nanocomposites treated by microwave radiation, MDF dust was desirably compounded with thermoplastic materials.

The allelopathic effects of leaves at rosette stage of the hoary alyssum (Berteroa incana L.) against some associated grasses like, prairie June grass (Koeleria macrantha), Idaho fescue (Festuca idahoensis), blue-bunch wheatgrass (Pseudoroegneria spicata) and cheat grass (Bromus tectorum) and its own were investigated. The experiment al materials used were the leaf extracts and its allelopathic effects on seed germination and seedling emergence of the abave mentioned grasses in Petri dishes. According to our study, leaves of hoary alyssum rosettes at stage have the potential to reduce germination rate, root and shoot growth of pasture grasses and hoary alyssum itself due to its allelopathic effect. The leaf leachate solution bioassays also showed that the germination of cheat grass was more susceptible to 4% solution of allelopathic extract of leaves. Hoary alyssum leaf extract also exhibited allelopathic self-inhibition, in both seedling root and shoot growth at 2 and 4% concentrations. Self- inhibitory allelopathic effects of hoary alyssum could also be important in preventing seed germination and seedling establishment of neighboring plant.

This study focuses on the online morphology development of a typical immiscible polymer blend subjected to a shear flow field in the presence of the high percentage of an interfacial modifier. The blend components were fluid at room temperature. To follow the details of the morphology development more closely, a drop-in-matrix structure was selected. The matrix and the dispersed phases were polyisobutylene (PIB) and polydimethylsiloxane (PDMS) of various viscosities, respectively. The selected three viscosities of PDMS generated a wide range of viscosity ratios, i.e., 0.04 to 2.3, at room temperature. Both polymers exhibited Newtonian behavior over the investigated shear rate range and no normal forces were observed. The interfacial modifier was a diblock copolymer including PIB and PDMS blocks with close molecular weight. The shear flow field was made using a coaxial cylinders system. The velocity of each cylinder was controlled separately. The results obtained for the blend system in the absence of an interfacial modifier were similar to the observations of previous researchers. A symmetrical breakup was observed for clean drops with the odd number of the resulting breakup droplets. The addition of the interfacial modifier drastically influenced the blend morphology development. The deformation of the compatibilized drops was considerably different from the deformation observed for the corresponding clean counterparts. The breakup was no longer symmetrical and predictable. The viscosity ratio played a determining role in morphology development of the compatibilized drop. The deformation and breakup of the drops at low and high viscosity ratios were not similar. While the low viscosity ratio of the compatibilized drops demonstrated tip-streaming at low shear rates and the high viscosity ratio of the drops showed end-pinching.