Maryam Shahsavari

Bio: Maryam Shahsavari is an academic researcher from Islamic Azad University. The author has contributed to research in topics: Matrix metalloproteinase & Pathology. The author has an hindex of 1, co-authored 1 publications receiving 128 citations.

Evaluation of Matrix Metalloproteinases 2 and 9 in Oral Squamous Cell Carcinoma and Verrucous Carcinoma

Abstract: Background: Squamous cell carcinoma (SCC) is the most common malignancy of the oral cavity with a highly aggressive nature. Verrucous carcinoma (VC) is a low-grade SCC with mild clinical and pathological characteristics. Extracellular matrix degradation (ECM) by several proteolytic enzymes, especially matrix metalloproteinases (MMPs), is an important factor in tumor growth, invasion, and metastasis. Objectives: The aim of this study was to evaluate the expression level of immunohistochemistry of MMPs 2 and 9 in SCC and VC of oral cavity. Methods: The present study was conducted on the data of 20 SCC and 18 VC samples obtained from the pathology department archives. Microscopic examination was performed after immunohistochemical staining of the samples for MMP-2 and MMP-9. Data analysis was performed in SPSS 20 software. Kruskal-Wallis test was used to compare variables between groups. Results: All SCC and VC samples were positive for MMP-2 and MMP-9. The mean expression level of MMP-9 was 24.41 ± 20.68 in VC and 48.27 ± 12.11 in SCC. The mean expression level of MMP-9 in SCC was higher than VC. In addition, the expression level of MMP-9 varied in different histopathological grades of SCC. Matrix metalloproteinase expression levels were different in SCC grades and was especially higher in grade III. The mean expression level of MMP-2 in VC was 35.28 ± 30.63 and in SCC was 23.50 ± 12.68. The mean expression level of MMP-2 in VC was higher than SCC. Conclusions: Our findings showed that the expression levels of MMPs 2 and 9 in SCC and VC are higher than healthy tissue.

Variational approach for wave dispersion in anisotropic doubly-curved nanoshells based on a new nonlocal strain gradient higher order shell theory

Abstract: In this paper, a variational approach for the wave dispersion in anisotropic doubly-curved nanoshells is presented. To study the doubly-curved nanoshell as a continuum model, a new size-dependent higher-order shear deformation theory is introduced. In order to capture the small scale effects, nonlocal strain gradient elasticity theory has been implemented. The present model incorporates two scale coefficients to examine the wave characteristics much accurately. Based on Hamilton’s principle, the governing equations of the doubly-curved nanoshells are obtained. These equations are solved via analytical approach. From the best knowledge of authors, it is the first time that present formulation is used to investigate the wave dispersion in anisotropic doubly-curved nanoshells. Also, it is the first time that small scale effects are considered in doubly-curved nanoshells made of anisotropic materials. Unlike the classical (scaling-free) model, the presented nonlocal strain gradient higher-order model shows a good calibration with the experimental frequencies and phase velocities. It is demonstrated that the material properties, nonlocal-strain gradient parameters and wave number have remarkable influences on wave frequencies and phase velocities. Presented results for wave dispersion can serve as benchmarks for future analysis of doubly-curved nanoshells.

Galerkin’s approach for buckling analysis of functionally graded anisotropic nanoplates/different boundary conditions

Abstract: For the first time, buckling behavior of functionally graded (FG) nanoplates made of anisotropic material (beryllium crystal as a hexagonal material) is investigated. Also, it is the first time that the size-dependent behavior of nanostructured systems is studied for buckling response of the graded anisotropic material. The properties of graded material are assumed vary exponentially through the z-direction. Nonlocal strain gradient theory is utilized to predicate the size-dependent buckling behavior of the nanoplate. The nanoplate is modeled by a higher order shear deformation refined plate theory in which any shear correction factor not used. Governing equations and boundary conditions are obtained using a virtual work of variational approach. To solve the buckling problem for different boundary conditions, Galerkin’s approach is utilized. Finally, the influences of different boundary conditions, small-scale parameters, geometry parameters and exponential factor are studied and discussed in detail. It is hoped that the present numerical results can help the engineers and designers to understand and predict the buckling response of FG anisotropic materials.

Porosity-dependent vibration analysis of FG microplates embedded by polymeric nanocomposite patches considering hygrothermal effect via an innovative plate theory

Abstract: The sandwich structures contain three or more layers attached to the core. In the current research, a three-layered sandwich microplate containing functionally graded (FG) porous materials as core and piezoelectric nanocomposite materials as face sheets subjected to electric field resting on Pasternak foundation is chosen as a model to investigate its vibrational behavior. To make the face sheets stiffer, they are reinforced by carbon nanotubes (CNTs) via different distribution patterns which result in changing their properties along the thickness direction. An innovative quasi-3D shear deformation theory with five unknowns, Hamilton’s principle, and modified couple stress theory are hired to gain equations of motion related to the abovementioned microstructure. Eventually, the evaluation of materials’ properties, geometry specifications, foundation moduli, and hygrothermal environment on vibrational behavior of such structures became easier using the presented results of the current study in figure format. As an instance, it is revealed that CNTs’ volume fraction elevation causes mechanical properties improvement, and in the following, natural frequency increment. Besides, considering the hygrothermal environment causes significant effects on the results.