Effect of Microwave Irradiation on Morphology and Size of Anatase Nano Powder: Efficient Photodegradation of 4-Nitrophenol by W-doped Titania

Shojaei, Abdollah Fallah,Loghmani, Mohammad Hassan Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.12

Anatase nanocrystalline and its tungsten-doped (0.4, 2, and 4 mol %) powders have been synthesized by microwave irradiation through hydrolysis of titanium tetra-isopropoxide (TIP) in aqueous solution. The materials are characterized by XRD, Raman, SEM-EDX, TEM, FT-IR and UV-vis techniques. The nanocrystalline $TiO_2$ particles are 30 nm in nature and doping of tungsten ion decreases their size. As seen in TEM images, the crystallites of W (4 mol %) doped $TiO_2$ are small with a size of about 10 nm. The photocatalytic activity was tested on the degradation of 4-nitrophenol (4-NP). Catalytic activities of W-doped and pure $TiO_2$ were also compared. The results show that the photocatalytic activity of the W-doped $TiO_2$ photocatalyst is much higher than that of pure $TiO_2$. Degradation decreases from 96 to 50%, during 115 min, when the initial 4-NP concentration increases from 10 to 120 ppm. Maximum degradation was obtained at 35 mg of photocatalyst.

Mechanical and Electronic Properties of π-Conjugated Metal Bis(dithiolene) Complex Sheets

Shojaei, Fazel,Hahn, Jae Ryang,Kang, Hong Seok American Chemical Society 2014 Chemistry of materials Vol.26 No.9

<P>Using first-principles calculations, we have investigated the mechanical properties and electronic structures of π<SUP>–</SUP>conjugated metal bis(dithiolene) complex sheets (MC<SUB>4</SUB>S<SUB>4</SUB>), where M = Ni and Pd. First, the sheets are much softer than graphene due to their large porosity. At zero strain, NiC<SUB>4</SUB>S<SUB>4</SUB> is a semiconductor with an indirect gap, while PdC<SUB>4</SUB>S<SUB>4</SUB> is a metal. Under either biaxial or uniaxial strain, our band structure analysis demonstrates that the band gap of the NiC<SUB>4</SUB>S<SUB>4</SUB> slowly decreases to zero with increased strain, which can be attributed to the gradual weakening of π-bonds of the sheet. However, the PdC<SUB>4</SUB>S<SUB>4</SUB> becomes a magnetic system beyond the deformation threshold that causes a plastic deformation along the <I>X</I>-axis. In addition, we also observe that both two-dimensional sheets undergo different types of nonreversible plastic changes under the uniaxial strains along the <I>X</I>- and <I>Y</I>-axes.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2014/cmatex.2014.26.issue-9/cm500767u/production/images/medium/cm-2014-00767u_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm500767u'>ACS Electronic Supporting Info</A></P>

Efficient non-linear analysis and optimal design of biomechanical systems

Shojaei, I.,Kaveh, A.,Rahami, H.,Bazrgari, B. Techno-Press 2015 Biomaterials and biomedical engineering Vol.2 No.4

In this paper a method for simultaneous swift non-linear analysis and optimal design/posture of mechanical/biomechanical systems is presented. The method is developed to get advantages of iterations in non-linear analysis and/or generations in genetic algorithm (GA) for the purpose of efficient analysis within the optimal design/posture. The method is applicable for both size and geometry optimizations wherein material and geometry non-linearity are present. In addition to established mechanical systems, the method can solve biomechanical models of human musculoskeletal system. Optimization-based procedures are popular methods for resolving the redundancy at joints wherein the number of unknown muscle forces is far more than the number of equilibrium equations. These procedures involve optimization of a cost function(s) which is assumed to be consistent with the central nervous system's strategy when activating muscles to assure equilibrium. However, because of the complexity of biomechanical problems (i.e., due to non-linear biomaterial, large deformation, redundancy of the problem and so on) efficient analysis are required within optimization procedures as suggested in this paper.

High Selective Oxidation of Alcohols Based on Trivalent Ion (Cr³⁺ and Co³⁺) Complexes Anchored on MCM-41 as Heterogeneous Catalysts

Shojaei, Abdollah Fallah,Rafie, Mahboubeh Delavar,Loghmani, Mohammad Hassan Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.8

Cr(III) and Co(III) complexes with acetylacetonate were anchored onto a mesoporous MCM-41 through Schiff condensation. The materials were characterized by XRD, FT-IR, BET, CHN and ICP techniques. Elemental analysis of samples revealed that one C=N bond was formed through Schiff condensation on MCM-41 surface. The catalysts were tested for the alcohol oxidations using t-butyl hydroperoxide (TBHP) and $H_2O_2$ as oxidant. The catalytic experiments were carried out at both room temperature and reflux condition. Various solvents such as dichloromethane, acetonitrile and water were examined in the oxidation of alcohols. Among the different solvents, catalytic activity is found more in acetonitrile. Further, the catalysts were recycled three times in the oxidation of alcohols and no major change in the conversion and selectivity is observed, which shows that the immobilized metal-acetylacetonate complexes are stable under the present reaction conditions.

Seismic vulnerability assessment of low-rise irregular reinforced concrete structures using cumulative damage index

Shojaei, Fahimeh,Behnam, Behrouz Techno-Press 2017 Advances in concrete construction Vol.5 No.4

Evaluating seismic performance of urban structures for future earthquakes is one of the key prerequisites of rehabilitation programs. Irregular structures, as a specific case, are more susceptible to sustain earthquake damage than regular structures. The study here is to identify damage states of vertically irregular structures using the well-recognized Park-Ang damage index. For doing this, a regular 3-story reinforced concrete (RC) structure is first designed based on ACI-318 code, and a peak ground acceleration (PGA) of 0.3 g. Some known vertical irregularities such as setback, short column and soft story are then applied to the regular structure. All the four structures are subjected to seven different earthquakes accelerations and different amplitudes which are then analyzed using nonlinear dynamic procedure. The damage indices of the structures are then accounted for using the pointed out damage index. The results show that the structure with soft story irregularity sustains more damage in all the earthquake records than the other structures. The least damage belongs the regular structure showing that different earthquake with different accelerations and amplitudes have no significant effect on the regular structures.

A Multidisciplinary Work-Related Low Back Pain Predictor Questionnaire: Psychometric Evaluation of Iranian Patient-Care Workers

Shojaei Sarallah,Tavafian Sedigheh Sadat,Ahmad Reza Jamshidi,Wagner Joan 대한척추외과학회 2016 Asian Spine Journal Vol.10 No.3

Study Design: Psychometric evaluation design. Purpose: Psychometric evaluation of a multidisciplinary work-related low back pain predictor questionnaire (MWRLBPPQ) of Iranians patient-care workers based on the social cognitive theory. Overview of Literature: Healthcare is one of the professions in which work-related musculoskeletal disorders are prevalent. The chronic low back pain experienced by patient caregivers can negatively impact their professional performance, and patient handling in a hospital is the main cause of low back pain in this population. Methods: This was a cross-sectional study carried out in Qom, Iran from July 2014 to November 2014. A MWRLBPPQ based on nine concepts of the social cognitive theory and existing literature regarding chronic low back pain was developed. Ten patient-care workers first completed the questionnaire as a pilot test, allowing the ambiguities of the instrument to be resolved. Exploratory factor analysis was used to confirm construct validity. This questionnaire was distributed among 452 patient-care workers in hospitals located in different geographically areas in Qom, Iran. Cronbach’s Alpha was calculated to assess reliability. Results: In all, 452 caregivers of patients with mean age of 37.71 (standard deviation=8.3) years participated in the study. An exploratory factor analysis loaded seven concepts of self-efficacy, knowledge, outcome perception, self-control, emotional coping, and selfefficacy in overcoming impediments and challenges in the environment. All concepts were jointly accounted for 50.08% of variance of behavior change. The Cronbach’s alpha coefficient showed favorable internal consistency (alpha=0.83), and test-retest of the scale with 2-week intervals indicated an appropriate stability for the MWRLBPPQ. Conclusions: The MWRLBPPQ is a reliable and valid theory-based instrument that can be used to predict factors influencing workrelated low back pain among workers who lift and transfer patients in hospitals.

New laboratory techniques (novel) in making organic-mineral mulch to control wind and water erosion and its use in global scale

Shojaei Saeed,Ardakani Mohammad Ali Hakimzadeh,Sodaiezadeh Hamid,Jafari Mohammad,Afzali Seyed Fakhreddin 대한공간정보학회 2021 Spatial Information Research Vol.29 No.1

In recent decades, wind erosion is increasing across the world as a result of climate change and drought. Therefore, in this study we aim to make mulch with new formulation in order to control wind and water erosion. The materials have been chosen based on their efficiency, availability, and cheapness. Also, cement, gypsum, lime, and blackstrap mixture were selected to make organicmineral mulch. Moreover, we applied response surface method to design and optimize the conditions of the experiment. In this study, we applied central composite design using 10–50 g of gypsum, 12.5–62.5 g of lime, 2.5–12.5 g of blackstrap, and 2.5–12.5 g of cement. The results showed that as all materials cause an increase in the resistance of soil as they are used more, and ultimately they lead to a decrease in erosion except for gypsum which has opposite reaction in high density. Furthermore, in order to reach the minimum wind erosion, a mixture of cement 6.43 g, blackstrap 9.25 g, gypsum 37.26 g, lime 48.92 g was suggested by design-expert software. Based on this experiment, the lowest minimum amount of water erosion was obtained when 5.86 g of blackstrap, 5.13 g of cement, 31.65 g of gypsum, and 46.83 g of lime were applied in the mixture. Analysis of variance showed that data simulation and comparison with real data are highly accurate. (90% accurate) Therefore, the formulation in this study has enough standards to be utilized to control erosion in many regions in the world.

Efficient non-linear analysis and optimal design of biomechanical systems

Shojaei, I.,Kaveh, A.,Rahami, H.,Bazrgari, B. Techno-Press 2015 Biomaterials and Biomechanics in Bioengineering Vol.2 No.4

In this paper a method for simultaneous swift non-linear analysis and optimal design/posture of mechanical/biomechanical systems is presented. The method is developed to get advantages of iterations in non-linear analysis and/or generations in genetic algorithm (GA) for the purpose of efficient analysis within the optimal design/posture. The method is applicable for both size and geometry optimizations wherein material and geometry non-linearity are present. In addition to established mechanical systems, the method can solve biomechanical models of human musculoskeletal system. Optimization-based procedures are popular methods for resolving the redundancy at joints wherein the number of unknown muscle forces is far more than the number of equilibrium equations. These procedures involve optimization of a cost function(s) which is assumed to be consistent with the central nervous system's strategy when activating muscles to assure equilibrium. However, because of the complexity of biomechanical problems (i.e., due to non-linear biomaterial, large deformation, redundancy of the problem and so on) efficient analysis are required within optimization procedures as suggested in this paper.

Electronic structure of the germanium phosphide monolayer and Li-diffusion in its bilayer

Shojaei, F.,Kang, H. Royal Society of Chemistry 2016 Physical chemistry chemical physics Vol.18 No.47

<P>Based on the first-principles calculations, we predict that the monoclinic GeP can be exfoliated into two-dimensional (2D) monolayers. In fact, the interlayer van der Waals interactions are found to be comparable to those in black phosphorus. For the first time, we also elaborate mechanical and electronic properties of the monolayer for possible applications in optoelectronics. Although the monolayer is an indirect-gap semiconductor, it turns into a direct-gap material under appropriate strain. Namely, the material exhibits a direct gap of 2.27 eV under 2% in-plane contraction along the softer (= a) axis. In addition, the contraction brings about an appreciable decrease in the effective mass of electrons along the b direction. The monolayer also practically turns into a direct-gap material under 4% tensile strain along the b direction. These results are particularly interesting, because our calculation indicates that the monolayer is about four times softer than graphene. Based on the calculation of activation barriers for various possible paths, we also identify anisotropic Li-diffusion paths on the GeP monolayer as well as in the interlayer region of its bilayer. In the interlayer region, four parallel paths are identified along the b direction, where a Li atom can diffuse similar to 50 times faster than in the graphene bilayer. Our detailed calculations suggest that GeP can be also useful as an anode material in lithium ion batteries.</P>

Effect of Si–Si Bonds in Silicon-Doped α-Phosphorene Bilayers: Two-Dimensional Layers and One-Dimensional Nanoribbons

Shojaei, Fazel,Hahn, Jae Ryang,Kang, Hong Seok American Chemical Society 2016 The Journal of Physical Chemistry Part C Vol.120 No.30

<P>We investigate the geometrical and electronic structures of various configurations of 2Si-doped two-dimensional (2D) bilayers of black phosphorene (alpha P)(2), in which two P atoms are substituted by Si atoms. Our first-principles calculations suggest that doping is cooperative, which is clearly manifested in the formation of Si-Si bonds in the two most stable configurations. As a result, both configurations become indirect-gap semiconductors, which differ from that of the pristine 2D bilayer. On the one hand, 2Si-doped armchair phosphorene nanoribbon (APNR) bilayers possess pseudodirect band gaps in the most stable configuration, which are one-dimensional materials cut with armchair edges saturated with hydrogen atoms. Comparisons of the deformation energy and the activation barrier suggest that Stone-Wales (SW) deformation can occur substantially more easily in the doped APNR than in carbon nanotubes, and molecular dynamics simulations show that the SW defect will be kinetically stable. This is because the deformation brings about shortening and strengthening of weak Si-Si bonds. As a result, the APNRs turn into real direct-gap materials.</P>