Sharif Digital Repository

Damage detection by Piezoelectric Wafer Active Sensors is one of the emerging efficient and dominant Structural Health Monitoring (SHM) methods. These sensors assess the health state of the structure due two strategies: a) near-field damage detection, b) far-field damage detection. The far-field damage detection is based on the high frequency Lamb wave propagation. As wave travels in a damaged structure, phase and amplitude of the wave will be changed. So comparison of the received signal from the pristine structure with damaged structure can give useful information about the health state of the structure. As PWAS is the essential part of this method, simulation and modeling of this sensors... 

Due to their potential to recover strength and stiffness with a minimum impact on aerodynamic performance of a damaged structure, scarf repairs are boosted as a viable repair option for primary aero-structures. However, due to the contradictory effect of the scarf angle on satisfying the airworthiness criteria for adhesively repaired structure, including the Design Limit Load and the Design Ultimate Load, certifying an adhesively scarf repair for primary airframes is a sophisticated and in some cases impossible process. So far, most of the experimental and numerical studies have been limited to joint specimens and their equivalent 2 Dimensional models and a few number of studies attempted to... 

Hybrid nanoparticle comprising of nanosilica (NS) and nanodiamond (ND), as denoted by ND@NS, was synthesized by a two-step chemistry route and then incorporated into styrene-butadiene rubber (SBR) at low concentrations up to 5 phr by a two-roll mill. Physical hybrids of NS and ND, i.e., ND&NS, with a weight ratio similar to chemical hybrid (80:20 for NS:ND), were also incorporated into SBR. Field emission scanning electron microscopy observations revealed very fine dispersion of nanoparticles in the case of physical hybrids (ND&NS); whereas, agglomerations and aggregation of nanoparticles were evidenced for ND@NS. Tensile and dynamic mechanical analyses exhibited a higher reinforcing effect... 

Bio-based shape memory polymers with fast-response have high potential for use in medical applications. In this study, biocompatible and biodegradable nanocomposites based on shape memory polyurethane acrylates (SMPUA)/cellulose nanocrystals (CNC), were synthesized by in-situ polymerization. CNC is a natural and renewable nanoparticle that has been considered for medical applications due to its excellent mechanical and biological properties and surface chemistry. At the first phase of this study, in order to synthesize UV-curable shape memory polyurethane acrylate, polycaprolactone diol (PCL-Diol), hexamethylene diisocyanate (HDI) and hydroxyethyl methacrylate (HEMA) were used as an reactive... 

Combustion synthesis is the best and most effective method for producing ceramic nano-composites which is also a simple and economic way of producing very fine powders with high purity. In this method, a series of combustion reactions named aqueous combustion analysis are used for producing single-phase and nano-composite products ,in which the heat produced in reactions are used for completing the phase . several chemical substances such as glycine ,urea ,ammonium acetate and others are used as combustion agents. In order to obtain optimized nano fuel, we produced alumina powder with multiple combustion percentages and composition of 25%moli ammonium acetate (AA) with 75%moli urea was... 

Shape memory polymers have the potential to use in the field of biomedical applications. In this research, polyurethane structures have been synthesized based on the Diol mixtures, consisting of polycaprolactane diol (PCL-diol) and poly (lactic acid) diol (PLA-diol). Aim of reasearch is about evaluating poly (lactic acid) effect in structure of the polyurethane. At the same time, cellulose nanocrystals (CNC) have been added to polymer matrix to improve properties. The synthesis of acrylated polyurethane, included the synthesis of polyurethane acrylate prepolymer. Next, this prepolymer has been cured by adding the reactive diluent and some polyol. The cured systems were investigated, finally,... 

The objective of this research is to evaluate different morphologies of UiO-66 structures (pristine state and UiO-66 structure chemically supported on graphene oxide (UiO-66@GO)), on the rheology of polyurethane acrylate nanocomposites prior to UV-curing. The synthesized nanoparticles were characterized by FTIR, FESEM, TGA, XRD, and BET analysis. Rheological investigations, including large amplitude oscillatory sweep, small amplitude oscillatory sweep, steady shear flow, and thixotropic analysis were utilized. Moreover, the obtained rheological results were fitted using the Carreau–Yasuda model, the power-law model, and the Herschel–Bulkley model for quantitative interpretations. The results... 

Biocompatible materials play a fundamental role in the advancement of medical science and provide groundbreaking solutions for tissue engineering and various therapeutic applications. Among these materials, polyurethane acrylate has attracted attention due to its biocompatibility, versatility, and suitability for creating complex medical scaffolds. This research investigates an innovative approach to reinforce polyurethane acrylate by incorporating graphene quantum dots, with the aim of developing advanced scaffolds for tissue engineering. The incorporation of graphene quantum dots is designed to take advantage of their exceptional properties to improve the mechanical strength, thermal... 

Prostate cancer is the second leading cause of cancer-related mortality in men after lung cancer. Prostate-specific membrane antigen (PSMA-617) labeled with Actinium-225 (225Ac) is currently being studied as a potential treatment for metastatic castration-resistant prostate cancer. This study aimed to produce the labeled compound [225Ac]Ac-PSMA-617 for the treatment of prostate cancer and its metastases. The compound was synthesized under optimized labeling conditions, and its radiochemical purity was determined to be over %96 using RTLC chromatography method. The biodistribution of the compound was evaluated in the tissues of healthy male mice, and the injected activity per unit mass of...