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New insights on the role of chondroitin sulfate proteoglycans in neural stem cell–mediated repair in spinal cord injury

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Neural Regeneration Research 2025年第6期20卷 1699-1700页

作者： Seyed mojtaba Hosseini Soheila Karimi-Abdolrezaee Department of Physiology and Pathophysiology Spinal Cord Research CentreRady Faculty of Health SciencesUniversity of ManitobaWinnipegMBCanada Manitoba Multiple Sclerosis Research Center WinnipegMBCanada Children Hospital Research Institute of Manitoba WinnipegMBCanada

Extensive neurodegeneration is a hallmark of traumatic spinal cord injury (SCI) that underlies permanent sensorimotor and autonomic impairments (Alizadeh et al.,2019).Following the primary impact,the spinal cord undergoes a cascade of secondary injury mechanisms that are driven by disruption of the blood-spinal cord ba rrier,vascula r inju ry,glial reactivity,neu roinfla mmation,oxidative stress,lipid peroxidation,and glutamate excitotoxicity that culminate in neuronal and oligodendroglial cell death,demyelination,and axonal damage(Alizadeh et al.,2019).To achieve a meaningful functional recovery after SCI,regeneration of new neurons and oligodendrocytes and their successful growth and integration within the neural network are critical steps for reconstructing the damaged spinal cord tissue (Fischer et al.,2020).

关键词： peroxidation Fischer injury

Voronoi Based Discrete Least Squares Meshless Method for Heat Conduction Simulation in Highly Irregular Geometries

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Chinese Journal of Mechanical Engineering 2016年第1期29卷 98-111页

作者： LABIBZADEH mojtaba Assistant Professor of Structural Engineering Civil Engineering DepartmentFaculty of EngineeringShahid Chamran University

A new technique is used in Discrete Least Square Meshfree（DLSM） method to remove the common existing deficiencies of meshfree methods in handling of the problems containing cracks or concave boundaries. An enhanced Discrete Least Squares Meshless method named as VDLSM（Voronoi based Discrete Least Squares Meshless） is developed in order to solve the steady-state heat conduction problem in irregular solid domains including concave boundaries or cracks. Existing meshless methods cannot estimate precisely the required unknowns in the vicinity of the above mentioned boundaries. Conducted researches are limited to domains with regular convex boundaries. To this end, the advantages of the Voronoi tessellation algorithm are implemented. The support domains of the sampling points are determined using a Voronoi tessellation algorithm. For the weight functions, a cubic spline polynomial is used based on a normalized distance variable which can provide a high degree of smoothness near those mentioned above discontinuities. Finally, Moving Least Squares（MLS） shape functions are constructed using a varitional method. This straight-forward scheme can properly estimate the unknowns（in this particular study, the temperatures at the nodal points） near and on the crack faces, crack tip or concave boundaries without need to extra backward corrective procedures, i.e. the iterative calculations for modifying the shape functions of the nodes located near or on these types of the complex boundaries. The accuracy and efficiency of the presented method are investigated by analyzing four particular examples. Obtained results from VDLSM are compared with the available analytical results or with the results of the well-known Finite Elements Method（FEM） when an analytical solution is not available. By comparisons, it is revealed that the proposed technique gives high accuracy for the solution of the steady-state heat conduction problems within cracked domains or domains with concave boundaries a

关键词： Discrete Least Squares Meshless crack Voronoi tessellation concave boundaries Steady-state heat conduction.

Numerical study of a multiple post-tensioned rocking wall-frame system for seismic resilient precast concrete buildings

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Earthquake Engineering and Engineering Vibration 2022年第2期21卷 377-393页

作者： Afshin Naserpour mojtaba Fathi Department of Civil Engineering Engineering FacultyRazi UniversityKermanshah ***Iran

A multiple rocking wall-frame(MRWF)system,in which the wall panels are directly connected to the adjacent beams and foundation is presented *** the MRWF system,the unbonded post-tensioned(PT)tendons are used to promote the self-centering ability,and O-shaped steel dampers are applied to enhance the energy dissipation capacity and reparability of the ***,analytical equations are proposed to determine the behavior of the O-shaped ***,the MRWF system is numerically evaluated for five different models consisting of rocking walls with varying numbers and arrangements while keeping the total effective width of wall panels *** numerical results show that with an increase in the number of wall panels and a decrease in the wall width,the hysteretic behavior of the MRWF system tends to the ideal flag-shaped pattern,resulting in little damage to the beams,insignificant strain in the wall toe,negligible residual drifts and damage index of less than 0.2 under severe *** contrast,the conventional model demonstrates extensive damage to the structural elements due to undesirable wall-to-frame interaction,which leads to a damage index of 0.78 and residual drifts of 0.42%under seismic loads.

关键词： precast wall-frame system rocking behavior post-tensioning O-shaped steel damper residual drift

DYNAMIC BEHAVIOR OF SEVERAL CRACKS IN FUNCTIONALLY GRADED STRIP SUBJECTED TO ANTI-PLANE TIME-HARMONIC CONCENTRATED LOADS

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Acta Mechanica Solida Sinica 2013年第6期26卷 691-705页

作者： mojtaba Ayatollahi Rasul Bagheri Faculty of Engineering University of ZanjanP.O.Box 45195-313ZanjanIran

This paper contains a theoretical formulations and solutions of multiple cracks sub- jected to an anti-plane time-harmonic point load in a functionally graded strip. The distributed dislocation technique is used to construct integral equations for a functionally graded material strip weakened by several cracks under anti-plane time-harmonic load. These equations are of Cauchy singular type at the location of dislocation, which are solved numerically to obtain the dislocation density on the faces of the cracks. The dislocation densities are employed to evaluate the stress intensity factor and strain energy density factors （SEDFs） for multiple cracks with differ- ent configurations. Numerical calculations are presented to show the effects of material properties and the crack configuration on the dynamic stress intensity factors and SEDFs of the functionally graded strip with multiple curved cracks.

关键词： anti-plane functionally graded strip multiple cracks screw dislocation

The influence of surface effects on Frederiks transition in nematic liquid crystal doped with ferroelectric nanoparticles

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Chinese Physics B 2018年第4期27卷 357-362页

作者： Erfan Kadivar mojtaba Farrokhbin Department of Physics Shiraz University of Technology Department of Physics Faculty of SciencesYazd University

Motivated by our recent work,in this work,we present the numerical study of the anchoring effect on the Frederiks threshold field in a nematic liquid crystal doped with ferroelectric colloidal *** weak anchoring conditions,we employ the relaxation method and Maxwell construction to numerically solve the Euler–Lagrangian differential equation for the total free energy together the Rapini–Papoular surface energy to take into account anchoring of nematic liquid crystal molecules at the *** this study,we focus our attention on obtaining the phase diagrams of Frederiks transition for different values of anchoring strength which have been not computed in our previous *** this way,the effect of nanoparticle radius,nanoparticle volume fraction,nanoparticle polarization,and cell thickness on the Frederiks transition for different values of anchoring conditions are summarized in the phase *** numerical results show that by increasing the nanoparticles size and nanoparticle volume fraction in the ferronematic system,the Frederiks threshold field is strongly reduced.

关键词： anchoring surface effect ferronematics Frederiks transition Maxwell construction

Biomaterials for repair and regeneration of the cartilage tissue

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Bio-Design and Manufacturing 2019年第1期2卷 41-49页

作者： mojtaba Ansari Mahdi Eshghanmalek Department of Biomedical Engineering Meybod University Meybod. Iran Department of Biomedical Engineering University of Science and Art. Yazd Iran

The repair and regeneration of the diseases and damaged cartilage tissue are one of the most challenging issues in the field of tissue engineering and regenerative medicine. As the cartilage is a non-vascularized and comparatively acellular connective tissue, its ability to the self-restoration is limited to a large extent. Although there is a countless deal of experimental documents on this field, no quantifiable cure exists to bring back the healthy organization and efficacy of the impaired articular cartilage. Tissue reformative approaches have been of excessive curiosity in restoring injured cartilage. Bioengineering of the cartilage has progressed from the cartilage focal damages treatment to bioengineering tactics progress aiming the osteoarthritis procedures. The main focus of the present study is on the diverse potential development of strategies such as various categories of biomaterials applied in the reconstruction of the cartilage tissue.

关键词： Biomaterials Cartilage Tissue engineering Repair 3D bioprinting

Efficient imidazolium salts for palladium-catalyzed Mizoroki-Heck and Suzuki-Miyaura cross-coupling reactions

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Chinese Chemical Letters 2013年第5期24卷 433-436页

作者： mojtaba Amini mojtaba Bagherzadeh Sadegh Rostamnia Department of Chemistry Faculty of ScienceUniversity of Maragheh Chemistry Department Sharif University of Technology

The system,Pd（OAc）_2/imidazolium salts（L_2）,was found as an efficient catalyst in the Heck coupling reaction of olefins with aryl halides and Suzuki reactions of various aryl halides with aryl boronic acids under aerobic *** catalytic system demonstrates great tolerance to a wide range of groups on all substrates of aryl halides,alkenes and aryl boronic acids.

关键词： lmidazolium salt Heck coupling reaction Suzuki coupling reaction Pd(OAc)2

Efficiency of employing fiber-based finite-length plastic hinges in simulating the cyclic and seismic behavior of steel hollow columns compared with other common modelling approaches

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Earthquake Engineering and Engineering Vibration 2019年第4期18卷 777-794页

作者： mojtaba Farahi Saeed Erfani Department of Civil Engineering Amirkabir University of Technology

The accuracy and effi ciency of the modelling techniques utilized to model the nonlinear behavior of structural components is a signifi cant issue in earthquake engineering. In this study, the suffi ciency of three diff erent modelling techniques that can be employed to simulate the structural behavior of columns is investigated. A fi ber-based fi nite length plastic hinge (FB-FLPH) model is calibrated in this study. In order to calibrate the FB-FLPH model, a novel database of the cyclic behavior of hollow steel columns under simultaneous axial and lateral loading cycles with varying amplitudes is used. By employing the FB-FLPH model calibrated in this study, the interaction of the axial force and the bending moment in columns is directly taken into account, and the deterioration in the cyclic behavior of these members is implicitly considered. The superiority of the calibrated FB-FLPH modelling approach is examined compared with the cases in which conventional fi ber-based distributed plasticity and concentrated plasticity models are utilized. The effi ciency of the enumerated modelling techniques is probed when they are implemented to model the columns of a typical special moment frame in order to prove the advantage of the FB-FLPH modelling approach.

关键词： cyclic behavior seismic behavior fi ber-based fi nite-length plastic hinge model fi ber-based modelling techniques cyclic strength deterioration axial force-bending moment interaction

Numerical evaluation of passive control of shock wave/boundary layer interaction on NACA0012 airfoil using jagged wall

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Acta Mechanica Sinica 2016年第5期32卷 792-804页

作者： mojtaba Dehghan Manshadi Ramin Rabani Mechanical and Aerospace Engineering Department Malek-Ashtar University of TechnologyEsfahan Iran Department of Mechanical Engineering Yazd University

Shock formation due to flow compressibility and its interaction with boundary layers has adverse effects on aerodynamic characteristics, such as drag increase and flow separation. The objective of this paper is to appraise the practicability of weakening shock waves and, hence, reducing the wave drag in transonic flight regime using a two-dimensional jagged wall and thereby to gain an appropriate jagged wall shape for future empirical study. Different shapes of the jagged wall, including rectangular, circular, and triangular shapes, were employed. The numerical method was validated by experimental and numerical studies involving transonic flow over the NACA0012 airfoil, and the results presented here closely match previous experimental and numerical results. The impact of parameters, including shape and the length-to-spacing ratio of a jagged wall, was studied on aerodynamic forces and flow field. The results revealed that applying a jagged wall method on the upper surface of an airfoil changes the shock structure significantly and disintegrates it, which in turn leads to a decrease in wave drag. It was also found that the maximum drag coefficient decrease of around 17 % occurs with a triangular shape, while the maximum increase in aerodynamic efficiency（lift-to-drag ratio）of around 10 % happens with a rectangular shape at an angle of attack of 2.26？.

关键词： Jagged wall Passive flow control Shock wave/boundary layer interaction Aerodynamic efficiency