Sharif Digital Repository

Partial substitutions of Pr and Ce are known to suppress the superconducting state in REBa2Cu3O7-δ systems. We have substituted Ce for Gd in Gd1-xCexBa 2Cu3O7-δ compounds with x = 0.0-0.6 by the standard solid-state reaction technique. X-ray diffraction (XRD) experiments are performed and their results are refined by the Rietveld method. XRD analysis shows a predominantly single-phase perovskite structure with few impurity phases. Our resistivity results show that, by increasing the Ce content, Tc decreases, the transition temperature width increases, and in the normal state a metal-insulator transition (MIT) occurs at x c = 0.12. The normal state resistivity of the samples and their slopes... 

The wear and friction properties of G-Cu (Sn) composite coatings containing different amounts of graphite particles were examined. The presence of graphite particles improved antifriction properties of composite coatings. The effects of graphite percent in composite coating, tin content of matrix, load, speed and distance on the coefficient of friction and wear resistance of bronze-graphite composite coatings were studied. The results of the present studies revealed that hardness, wear resistance, coefficient of friction are dependent on volume percentage of graphite in composite coating. It was shown that the composite coating containing approximately 5.4 (vol.%) graphite and matrix with... 

The aim of this research is to obtain composite coatings of bronze (90% Cu-10% Sn) with graphite particles. The electrodeposition of G-Cu (Sn) composites from an alkaline bath containing cyanide is described. Composite coatings consisting of graphite particles and copper-tin were prepared by means of the conventional electrocodeposition (CECD) and sediment codeposition (SCD) techniques. The graphite particles involved were less than 10 μm. The dependence of graphite amount in the composite coatings was investigated in relation to the graphite concentration in bath, cathode current density, stir rate and technique type and it was shown that these parameters strongly affected the volume... 

Tailoring the properties of electrospun fibers requires a detailed understanding and control of their microstructure. We investigate the structure/property relationships in fabrics of randomly aligned fibers of polylactide, a prevalent biopolymer, either as-spun or after annealing and solvent-induced crystallization. In-depth characterization by field-emission scanning electron microscope (FESEM), wide-angle X-ray diffraction (WAXD), attenuated total reflection Fourier transform infrared (ATR-FTIR), and modulated temperature differential scanning calorimetry (MT-DSC) reveals that the as-spun fibers comprise crystalline and mesomorphic phases, as well as oriented but mobile amorphous chain... 

Co-deposition of Cu(Zn) and graphite powders with size less than 10 μ was studied. Electrocomposite coatings were prepared by means of the conventional electrodeposition (CECD) and the sediment co-deposition (SCD) techniques. Brass electroplating cyanide bath has been selected out of electrodeposition brass. The effect of parameters such as rate of agitation and current density on the composition of electrodeposition brass and also the effect of the concentration of graphite particles in brass bath, air agitation rate on graphite incorporation within brass matrix and deposition efficiency were studied. The wear and friction properties of G-Cu(Zn) composite coatings containing different... 

We present a procedure for simultaneous deposition of enzyme-laden chitosan/reduced graphene oxide (rGO) film by electrophoretic deposition (EPD) for fast and efficient detection of glucose. The role of rGO nanosheets is studied on the EPD kinetics of the enzyme-laden suspensions. Investigating the performance of the biosensor by electrochemical techniques indicates its high sensitivity (9700 μA.mM−1.cm−2), low limit of detection (4 µM), and suitable selectivity. © 2021 Elsevier B.V  

We have investigated the effect of Ca substitution for Sr site on structural, magnetic and superconducting properties of RuSr2 -x CaxGd1.4Ce0.6Cu2O10 -δ system. In this system, the magnetic coupling of RuO 2 and CuO 2 plays an important role in magnetic and superconducting states. X-ray diffraction analysis shows that all samples are single phase and the lattice parameters decrease continuously by increasing Ca content. The onset superconducting transition temperature is found to decrease with Ca substitution. As Ca content increases, rotation of the RuO 6 octahedron increases and RuO(1)Ru angle decreases. These variations strengthen the magnetic moments in the RuO 2 planes. The enhancement... 

Two-step sintering (TSS) was applied to suppress the accelerated grain growth of sub-micron (∼150 nm) alumina powder. The application of an optimum TSS regime led to a remarkable decrease of grain size down to ∼500 nm; while the grain size of the full-dense structures produced by conventional sintering ranged between 1 and 2 μm. To find how important the temperatures at sintering steps might be, several TSS regimes were conducted. The results showed that the temperatures at both sintering steps play vital roles in densification and grain growth of the alumina compacts. Based on the results, the optimum regime consisted of heating the green bodies up to 1250 °C (first step) and then holding... 

Three-dimensional porous nanocomposites consisting of gelatin-carboxymethylcellulose (CMC) cross-linked by carboxylic acids biopolymers and monophasic hydroxyapatite (HA) nanostructures were fabricated by lyophilization, for soft-bone-tissue engineering. The bioactive ceramic nanostructures were prepared by a novel wet-chemical and low-temperature procedure from marine wastes containing calcium carbonates. The effect of surface-active molecules, including sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium bromide (CTAB), on the morphology of HA nanostructures is shown. It is demonstrated that highly bioactive and monophasic HA nanorods with an aspect ratio > 10 can be synthesized in... 

For the rapid detection of hyperglycemia in human blood, we adopted a facile and two-step electrochemical procedure to prepare nickel/reduced graphene oxide (rGO) hybrid electrodes in the framework of a three-dimensional (3D) nanostructure. High-density and vertically-aligned nickel submicrorods with an average diameter of 155 ± 15 nm and a length of 7 ± 1 μm (an aspect ratio of about 40-50) were prepared by template-mediated electrochemical deposition techniques. Networks of rGO nanosheets between the rod-shaped arrays were formed by the cathodic electrophoretic deposition method. The synergistic effect of nickel morphology (planar and high-density rod-shaped arrays) and graphene oxide... 

Knowledge about the non-linear dynamical pattern of postural sway may provide important insights into the adaptability (flexibility) of human postural control in response to everyday stresses imposed on the body. A commonly used non-linear tool, i.e. recurrence quantification analysis, was chosen to investigate the effect of prior anterior cruciate ligament injury on the deterministic pattern of postural sway under different conditions of postural and cognitive difficulty. In double leg stance, as postural difficulty increased from open-eyes to closed-eyes and rigid-surface to foam-surface, the centre of pressure regularity (%determinism) increased as well. In comparison to healthy... 

The aims of this study were to culturally adapt and validate the Persian version of Foot and Ankle Outcome Score (FAOS) and present data on its psychometric properties for patients with different foot and ankle problems. The Persian version of FAOS was developed after a standard forward-backward translation and cultural adaptation process. The sample included 93 patients with foot and ankle disorders who were asked to complete two questionnaires: FAOS and Short-Form 36 Health Survey (SF-36). To determine test-retest reliability, 60 randomly chosen patients completed the FAOS again 2 to 6 days after the first administration. Test-retest reliability and internal consistency were assessed using... 

Several studies have investigated postural control in anterior cruciate ligament (ACL) deficient patients; yet the contribution of cognitive processing (attention) in the postural control of these patients is still unclear. A dual-task design was used to determine the effects of a concurrent digit span memory task on standing balance in a group of ACL patients (n = 27) compared with a group of matched, healthy participants (n = 27). In double limb stance, three levels of postural difficulty were studies on a force platform (rigid surface with eyes open, rigid surface with eyes closed, and foam surface with eyes closed). There were three cognitive conditions (no cognitive task, easy cognitive... 

STUDY DESIGN. Three factors mixed-design with 1 between-subject and 2 within-subject factors. OBJECTIVE. To compare the main effects and interactions of postural and cognitive difficulty on quiet stance between subjects with and without nonspecific low back pain (LBP). SUMMARY OF BACKGROUND DATA. The interference between postural control and cognitive tasks depends on factors such as sensorimotor/cognitive integrity. Changes in peripheral sensory and muscular systems as well as cognitive processes have been observed in LBP patients. It was hypothesized that the effect of cognitive task on postural performance might be different in subjects with nonspecific LBP as compared with healthy... 

Targeted delivery by either passive or active targeting of therapeutics to the bone is an attractive treatment for various bone related diseases such as osteoporosis, osteosarcoma, multiple myeloma, and metastatic bone tumors. Engineering novel drug delivery carriers can increase therapeutic efficacy and minimize the risk of side effects. Developmnet of nanocarrier delivery systems is an interesting field of ongoing studies with opportunities to provide more effective therapies. In addition, preclinical nanomedicine research can open new opportunities for preclinical bone-targeted drug delivery; nevertheless, further research is needed to progress these therapies towards clinical... 

The aim of this study was to estimate the test-retest reliability of some commonly used center of pressure measures in postural control investigations of sport injuries under the diverse stressful postural conditions. Twelve patients with anterior cruciate ligament injury were evaluated on two separate sessions. The center of pressure was recorded from force platform and the following measures were calculated (1) standard deviation of amplitude (2) mean velocity (3) standard deviation of velocity (4) phase plane parameters and (5) area (95% confidence ellipse). Relative and absolute reliability was assessed using intra-class correlation coefficient and coefficient of variation, respectively.... 

Targeted delivery by either passive or active targeting of therapeutics to the bone is an attractive treatment for various bone related diseases such as osteoporosis, osteosarcoma, multiple myeloma, and metastatic bone tumors. Engineering novel drug delivery carriers can increase therapeutic efficacy and minimize the risk of side effects. Developmnet of nanocarrier delivery systems is an interesting field of ongoing studies with opportunities to provide more effective therapies. In addition, preclinical nanomedicine research can open new opportunities for preclinical bone-targeted drug delivery; nevertheless, further research is needed to progress these therapies towards clinical... 

Reliability is a population-specific property, but to the authors' knowledge there has been no study to determine the test-retest reliability of the postural stability measures such as center of pressure (COP) measures in the population of patients with musculoskeletal disorders (MSDs), while their clinical applications have been presented in literature. So, 33 patients with low back pain (LBP), anterior cruciate ligament (ACL) injury and functional ankle instability (FAI) randomly completed postural measurements with three levels of difficulty (rigid surface-eyes open, rigid surface-eyes closed, and foam surface-eyes closed) in two sessions. COP data were used to calculate standard...