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Asghar Ali,Zuhair S. Khan,Mahmood Jamil,Yaqoob Khan,Nisar Ahmad,S. Ahmed 한국물리학회 2018 Current Applied Physics Vol.18 No.5
We developed sulfonated, reduced graphene oxide (S-RGO) through fuming/concentrated sulfuric acid treatment of graphene oxide (GO) in ambient conditions. It was demonstrated that the optical band gap and electrical conductivity of S-RGO are easily tunable, and depend on the level of reduction and sulfonation of GO. Whereas, reduction and sulfonation were found dependent on SO3 content, acid strength, and gas tightness of the reaction mixture. It's actually the water content of oleum that determines the nature of the final product. The easily adjustable band gap and electrical conductivity suggest that S-RGO can be employed as a potential hole extraction layer (HEL) material for several donor-acceptor systems. For P3HT:PC61BM based inverted polymer solar cells, it was observed that the shape of the JeV curve is tailorable with the choice of HEL. Compared to a 2.75% power conversion efficiency (PCE) attained with PEDOT:PSS, a PCE of 2.80% was achieved with tuned S-RGO. Our results imply that an S-RGO of sufficiently high band gap and conductivity can replace some of the state of the art HEL materials for a host of device applications.
Ali, Asghar,Biswas, Md Rokon Dowla,Areerob, Yonrapach,Nguyen, Dinh Cung Tien,Oh, Won-Chun The Korean Ceramic Society 2018 한국세라믹학회지 Vol.55 No.4
In this work, photocatalytic $CO_2$ reduction over a CdSe-graphene-$TiO_2$ nanocomposite has been studied. The obtained material was successfully fabricated via ultrasonic technique. The physical properties of the as-synthesized materials were characterized by some physical techniques. The $TiO_2$ and CdSe dispersed graphene nanocomposite showed excellent results of strong reduction rates of $CO_2$ compared to the results of bare $TiO_2$ and binary CdSe-graphene. An outstanding point of the combination of CdSe-$TiO_2$ and graphene appeared in the form of great photocatalytic reduction capability of $CO_2$. The photocatalytic activity of the asfabricated composite was tested by surveying for the photoreduction of $CO_2$ to alcohol under UV and visible light irradiation, and the obtained results imply that the as-prepared CdSe-graphene-$TiO_2$ nanocomposite is promising to become a potential candidate for the photocatalytic $CO_2$ reduction.
Ali Asghar Ghasemi,Hamid Reza Dowlatabadi 아시아영어교육학회 2018 The Journal of Asia TEFL Vol.15 No.3
This study aims to identify and investigate the role of task value (drawn from expectancy-value theory), surface/deep learning strategies, and critical thinking for predicting language learners’ selfregulation and ultimate language achievement in a single framework. To this end, 190 participants, majoring in English at bachelor’s level at a state university in Iran, were selected based upon convenience sampling. A structural equation model showed that both motivational and cognitive components were significant predictors of language achievement and self-regulation. The results reveal that task value is a positive predictor of deep/surface learning strategies and metacognitive selfregulation, which provides evidence that awareness of the importance and value of a task, directs learners to choose more appropriate self-regulation strategies to monitor their process of learning and structure their own cognitive manners. The findings demonstrated that critical thinking predicts improvement in language achievement. Theoretically speaking, it has been argued that the ability to critically analyze learning materials and evaluate information enables learners with advanced proficiency to actively take part in the learning process, be further dedicated to their tasks, and more effectively and efficiently engaged in learning strategies, therefore making more successful learners. Finally, the implication for teachers and policy makers is discussed.
Ali Asghar Atai,Mohammad Hassan Naei,Reza Eghtefari 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.11
Snap-through is an instability phenomenon that occurs in arch and dome-shaped structures, wherein the structure has to move from a stable equilibrium state through an unstable path into another stable equilibrated configuration in a jumping action. In this study, a linear elastic isotropic low arch is considered as a structure with power-law variable thickness. The phenomenon is investigated by considering the equation of the deflection for the variable thickness arch, solving it with an elegant analytical technique, and finding the snap-through critical load from an extreme condition. The effect of power-law exponent and geometry of the arch centerline on critical load is investigated and the constant thickness case and a very rare case of power-law thickness variation found in literature are considered for verification.
Ali, Asghar,Oh, Won-Chun The Korean Ceramic Society 2015 한국세라믹학회지 Vol.52 No.6
We examined the photo catalytic activity and catalytic recyclability of CdSe/graphene nanocomposites fabricated via modified hydrothermal technique. The prepared composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX), transmission electron microscopy (TEM), Raman spectroscopic analysis, and X-ray photoelectron spectroscopy (XPS). The photocatalytic behavior was investigated through decomposition of RBB as a standard dye under visible light radiation. Our results indicate that there is significant potential for graphene based semiconductor hybrids materials to be used as photocatalysts under visible light irradiation for the degradation of organic dyes from industry effluents.
Study of Lower Hybrid Current Drive for the Demonstration Reactor
Ali Asghar Molavi-Choobini,Ahmad Naghidokht,Zahra Karami 한국원자력학회 2016 Nuclear Engineering and Technology Vol.48 No.3
Steady-state operation of a fusion power plant requires external current drive to minimizethe power requirements, and a high fraction of bootstrap current is required. One of theexternal sources for current drive is lower hybrid current drive, which has been widelyapplied in many tokamaks. Here, using lower hybrid simulation code, we calculate electrondistribution function, electron currents and phase velocity changes for two options ofdemonstration reactor at the launched lower hybrid wave frequency 5 GHz. Two plasmascenarios pertaining to two different demonstration reactor options, known as pulsed(Option 1) and steady-state (Option 2) models, have been analyzed. We perceive thatelectron currents have major peaks near the edge of plasma for both options but withhigher efficiency for Option 1, although we have access to wider, more peripheral regionsfor Option 2. Regarding the electron distribution function, major perturbations are atpositive velocities for both options for flux surface 16 and at negative velocities for bothoptions for flux surface 64.
Ali-Asghar Shahamat,Nasrullah Rastegar-Pouyani,Eskandar Rastegar-Pouyani 국립중앙과학관 2019 Journal of Asia-Pacific Biodiversity Vol.12 No.3
Taxonomic evaluation is one of the challenges that are being faced by taxonomists. They use different criteria to evaluate taxonomic validity of a given lineage. In the present study, we evaluate different populations of Trapelus agilis in Iran by using morphoecological approach. Our morphological results confirmed separation of T. agilis khuzestanensis, southeastern Iran and Qom groups, from other central and northeastern groups. Ecological niche of T. agilis khuzestanensis and southeastern, Qom, and northeastern Iranian populations can be differentiated from other groups. Differences are due to local adaptations and the geological history of the taxa. The Central Iranian Plateau aridification, after Zagros Mountain uplifting, created constant environmental conditions, which may have affected the central Iranian groups. Other smaller groups distributed in southeastern Iran, T. agilis khuzestanensis, T. sanguinolentus, and Qom groups are isolated from central populations and adapted locally.
Ali Asghar Atai,Davood Lak 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.1
In this work, the effect of electric potential on the mechanical (Stresses, strains, displacement) and electrical (electrical displacementand intensity) response of a Functionally graded piezoelectric (FGP) hollow sphere is analytically investigated. The sphere is under theaction of internal/external pressure and temperature gradient as well. The inhomogeneity is based on power law in radial direction. Theanalysis is done in two parts: elastic response and plastic response, using Tresca yield criterion. It is shown by illustrative example thatunder internal pressure and assumed model parameters, the commencement of plastic region is from outside surface towards inside in theplastic zone is extended with the increase of electric potential. Interestingly, radial stress and displacement have an extreme not on theboundaries, but on the inside.
Small scale computational vibration of double-walled CNTs: Estimation of nonlocal shell model
Asghar, Sehar,Khadimallah, Mohamed Amine,Naeem, Muhammad N.,Ghamkhar, Madiha,Khedher, Khaled Mohamed,Hussain, Muzamal,Bouzgarrou, Souhail Mohamed,Ali, Zainab,Iqbal, Zafar,Mahmoud, S.R.,Algarni, Ali,Ta Techno-Press 2020 Advances in concrete construction Vol.10 No.4
In this paper, vibration characteristics of double-walled carbon nanotubes (CNTs) is studied based upon nonlocal elastic shell theory. The significance of small scale is being perceived by developing nonlocal Love shell model. The wave propagation approach has been utilized to frame the governing equations as eigen value system. The influence of nonlocal parameter subjected to diverse end supports has been overtly analyzed. An appropriate selection of material properties and nonlocal parameter has been considered. The influence of changing mechanical parameter Poisson's ratio has been investigated in detail. The dominance of boundary conditions via nonlocal parameter is shown graphically. The results generated furnish the evidence regarding applicability of nonlocal shell model and also verified by earlier published literature.
Ali Asghar Ghoreyshi,Fatemeh Gorzin 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.8
Elimination of Cr (VI) from aqueous solution was investigated by a new low cost activated carbon developed from aerobically digested activated sludge (ADAS). The adsorbent demonstrated remarkable characteristics such as high surface area of 760m2·g−1 and large total pore volume of 0.8383 cm3·g−1. The maximum equilibrium uptake of Cr (VI) was 70.15 mg·g−1 at optimum pH 2.0. Interpretation of equilibrium data revealed that the best description was provided by the Freundlich isotherm. The kinetics of Cr (VI) adsorption was well described by the pseudo-second order equation. Calculation of thermodynamic parameters revealed that the adsorption process was endothermic, spontaneous and feasible. The adsorbent was regenerated using NaOH and it was found to be suitable for reuse in successive adsorption-desorption cycles. The desorption efficiency of Cr (VI) ion was up to 78%. Finally, comparison of Cr (VI)adsorption capacity of the developed adsorbent with commercial activated carbon demonstrated its higher performance.