Background and Purpose Due to the high prevalence of Parkinson's disease (PD) in the elderly, a large financial burden is imposed on the families and health systems of countries in addition to the problems related to the mobility impairment caused by the disease for the patients. Studies on controversial issues in this disease are taken into consideration, and one of these cases is the role of serum homocysteine level in Parkinson's patients. In this study, the serum level of homocysteine and its association with various variables in relation to this disease was compared with healthy individuals. Materials and Methods In this study, 100 patients with PD and 100 healthy individuals as control group were investigated. Serum homocysteine level and demographic and clinical data were included in the checklist. Data were analyzed by SPSS version 23. In all tests, the significance level was below 0.05. Results The mean level of serum homocysteine in case and control groups was 14.93 ± 8.30 and 11.52 ± 2.86 µmol/L, respectively (95% CI: 1.68; 5.14, P < 0.001). In total patients, 85 had normal serum homocysteine level, while 15 had high serum homocysteine level. In controls, the homocysteine level was 98 and 2, respectively (P=0.002). In multivariate logistic regression analysis, serum homocysteine level higher than 20 µmol/L was accompanied by 8.64-fold in Parkinson's disease involvement (95% CI: 1.92; 38.90, P=0.005). Conclusion Increasing serum homocysteine level elevates the rate to having PD. Serum homocysteine levels did not have any relationship with the duration of the disease, type of cardinal manifestation, and the severity of Parkinson's disease.

In this study, free and forced vibration investigations and thermal buckling analysis of three-layered centrosymmetric piezoelectric microplates are examined. To model the size effects, the size-dependent consistent couple stress theory is used. To be compatible with the modified coupled stress theory, a modification is proposed to apply to the consistent couple stress theory. Resorting to the Navier’s approach, the governing equations are treated in the case of simply supported boundary conditions to extract the free and forced vibration outcomes and the thermal buckling numerical results. The verifications demonstrate the effectiveness of the proposed modification. The effects of the material length scale parameter and the flexoelectricity coefficient on the findings are investigated. Moreover, the closed- and open-circuit condition impacts on the free and forced vibration and the thermal buckling analyses are studied.

Present study aims to investigate the mechanical buckling including the shear buckling and the in-plane mechanical buckling of composite laminated plates reinforced with graphene sheets with temperature dependent features resting on Winkler-Pasternak elastic foundation in a thermal ambient. The governing equations in the framework of the first order shear deformation theory are attacked by the Ritz method. The plate is subjected to uniaxial, biaxial and shear loads. The innovation of the present paper is considering the temperature dependency and anisotropicity of the material properties of a nanocomposite layer that reinforced with graphene sheets for the purpose of the determination of the mechanical buckling treatment of a graphene reinforced composite (GRC) laminated plate with different boundary condition types. Resorting to the extended Halpin-Tsai micromechanical model, the thermo-mechanical characteristics of a lamina is defined. Numerical outcomes of the present study are confirmed with the presented data in the literature. The effects of the elastic foundation parameter, the temperature, the plate side to its thickness ratio, the layup scheme, the boundary condition type and the distribution pattern of graphene-reinforced composites on the critical buckling load are investigated. It is found that, the impact of elastic foundation incorporation is less visible on the critical shear buckling load rather than the critical uniaxial and biaxial mechanical loads. Moreover, the largest critical buckling load belongs to layup [0] 10 among the all under studied lamination schemes.

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Microelectromechanical systems (MEMS) have attracted researchers' attention due to their various applications.Microplates with piezoelectric face sheets are the impending choice for MEMS. Hence, in this paper, an analysis of free vibrations of such microplates reinforced with graphene platelets resting on an elastic foundation and subjected to an external voltage in a thermal ambient is performed. The first-order shear deformation theory and a modified couple stress theory are employed to derive their kinetic and strain energies. The thermomechanical features of the core layer, reinforced with graphene platelets, are determined using the Halpin-Tsai micromechanical model. The Ritz technique is used to find the associated natural frequencies for different boundary conditions. The impact of geometry of graphene platelets, their weight fraction, temperature increment, external voltage, and boundary conditions on the outcomes are examined. The results obtained showed that decrement of the fundamental natural frequency of the microplates depends on the increment of temperature.