On crack detection in curved beams using change of natural frequency

In this study, an inverse method for the purpose of identifying the parameters of a single-edge crack in a curved beam is investigated. This method requires both numerical and experimental natural frequencies. The differential quadrature element method (DQEM) is introduced to get the numerical ones. For the purpose of implementing the DQEM the beam is divided into some elements and the governing equations, the continuity and the boundary conditions, are exerted on these elements to create an eigenvalue problem which is solved to obtain the required frequencies. A rotational spring whose stiffness is a function of crack depth is used to model the crack. An objective function with the variables of crack location and depth which is the weighted mean squared error between experimental and numerical frequencies is defined. The artificial bee colony algorithm (ABC) an optimization algorithm inspired by the natural foraging behavior of honeybees is used to minimize the aforementioned objective function and obtain crack parameters. To investigate the accuracy of this non-destructive, fast and easy method, an experimental modal analysis test is conducted on a cracked beam. The results indicate that the position and depth of the crack can be determined successfully using this method. This test is done five times with a different crack depth each time, to show the efficiency of the method for all cracks even small ones. A brief investigation is also done on the effect of crack location and depth on the natural frequencies

Financial Liberalization and the Stability of Short-run and Long-run Money Demand in Iran

Money demand is one of the most important macro-economic variables that could be of great importance to the economic prospect of a country. Therefore, awareness on how this function behaves and by adoption of appropriate economic policies, it is possible, by and large, to avoid the emergence of disorder. The present study, employing the annual time series data related to Iranian economy during 1973-2009, tries to investigate possible relationships between financial liberalization and money demand stability in Iran, in the form of 4 models. To do so, Zivot-Andrews (1992) Unit Root Test was applied in order to clarify endogenous structural changes and Gregory-Hansen (1996) Cointegration Test was administered to investigate the long-run relationships between financial liberalization and money demand stability in Iran, with an emphasis on the structural breaks during the period under study. The results of the study show that by taking the structural break into consideration, there is a significant short and long run relationship between financial liberalization and money demand stability in Iran

Design and Synthesis of Curcumin Analogs for Anticancer Activity and Discovery of Novel Hit Molecules Targeting CXCR4.

Curcumin as a natural compound is made of various components including protein, carbohydrate, and curcuminoid. Curcuminoid is made of curcumin, desmethoxycurcumin and bis desmethoxycurcumin. Curcumin is used for the treatment of cancer and inflammatory disorders, but it has some therapeutic problems like poor bioavailability, poor efficacy, and chemical instability. To overcome these problems, the objective of this study is (1) synthesis of pyrazole curcumin analogs, (2) synthesis of triazole curcumin analogs, and (3) in-vitro study of the anticancer activity of these curcumin analogs on head & neck, breast, pancreatic and glioblastoma cancer cells. During this part of my Ph.D. project, we have synthesized 9 pyrazole and 4 triazole curcumin analogs and studied their anticancer activity against CAL 27 and UM-SCC-74A as head & neck cancer cell lines, MDA-MB-231 as breast cancer cell line, HPAF as pancreatic cancer cell line, and MG118 as glioblastoma cancer cell lines. We have studied the effect of these analogs on head & neck cancer cell lines by using cell proliferation assay and western blotting analysis. Compound 49 was shown the best anticancer activity on these cancer cell lines. Western blotting analysis revealed that compounds 49, 81, and 77, showed anticancer activity. We did MTS assay study on MDA-MB 231 as a human cancer cell line and the study revealed that compounds 6 and 81 had good anticancer activity against these cancer cell lines, while triazole analogs showed weak anticancer activity. We also used MTS assay study to investigate the effect of curcumin analogs. Compounds 6 and 86 showed good anticancer activity against HPAF cell line. Cell Titer Glo-2 assay study on MG118 cell line revealed that compounds 49, 51, and 80 had good anticancer activity against glioblastoma cancer cell lines. The expression of the CXCR4 gene leads to making a CXCR4 protein which is a GPCR protein. Research showed that this protein is involved in different cancer types. Overexpression of CXCR4 leads to cancer metastasis. The objective of this study as the second part of my Ph.D. project is the discovery of novel hit molecules targeting CXCR4. We did the virtual screening of 229358 natural product compounds. Based on the crystallography structure, we generated the receptor file. FRED docking led to the identification of 500 hit compounds out of 229358 compounds. 500 hit compounds were filtered based on several parameters which led to the identification of 4 hit molecules. Root Mean Square Deviation study has shown that two of these hit molecules stabilized the protein Structure. Moreover, based on the Radius of the gyration study, three of these molecules maintain the compactness of protein. The hydrogen bond study of these complexes showed that two complexes made hydrogen bonds with targets. So, molecular dynamic analysis by Gromacs led to the identification of 2 hit molecules for CXCR4 antagonist activity. Keywords: Curcumin, Cancers, In-vitro study

A novel vitamin B9 sensor based on modified screen-printed electrode

In the field of determination of vitamin B9 (folic acid, FA), we have described the development of a sensitive electrochemical sensor through promoting the screen-printed electrode (SPE) and taking the advantage of zinc ferrite magnetic nanoparticles (ZnFe2O4MNPs). Cyclic voltammetry (CV) experiments demonstrated the powerful activity of ZnFe2O4MNPs/SPE for electrooxidation of FA by showing the prominent oxidation peak at 600 mV vs. Ag/AgCl. By differential pulse voltammetry (DPV) measurements, a linear relation between current response and concentration of vitamin B9 was determined in the range of 1.0–100.0 μM, and detection limit is found to be 0.3 μM (S/N=3). Except high sensitivity, the developed sensor demonstrated high stability, reproducibility and repeatability, and was also successfully applied to specify FA in real samples of vitamin B9 tablets and human urine

Analysis and Topology Optimization of Adaptive Sandwich Plates treated with Magnetorheological Elastomer core layer

Structural vibration control is a promising method for mitigating the detrimental effects of excessive vibration in structures. It involves monitoring the dynamic behavior of a structure and implementing control strategies to reduce the vibration levels of the structure. Among various control methodologies, the semi-active control method adeptly combines the reliability characteristic of passive systems with the adaptability inherent in fully active systems, without requiring complex control hardware. Smart materials play a crucial role in implementing semi-active vibration control, and among them, magnetorheological (MR) materials have garnered substantial attention for their remarkable properties, including rapid response times and low energy consumption. Compared with MR fluids (MRFs) which can only provide variable damping, Magnetorheological elastomers (MREs) have field dependent viscoelastic properties in which both stiffness and damping properties can be effectively altered using the applied magnetic field. By incorporating MREs into the core of sandwich plates, it becomes possible to modify the continuous plate's vibration characteristics on-demand through application of an external magnetic field. Although employing complete coverage of the MRE core layer within a sandwich plate is likely to yield the best results in reducing vibration levels, it is essential to consider practical factors like mass limitations. Therefore, optimizing the topology of the MRE layer with a constrained volume fraction is of practical importance. The goal of the topology optimization process is to attain the desired vibration control performance while concurrently minimizing the mass or volume of the MRE layer. This enables the efficient utilization of MRE-based vibration control systems in real-world applications, where optimizing resources is crucial. To achieve this end, first a finite element model has been formulated to evaluate the vibration behavior of MRE-based sandwich plate under dynamic loading. The plate is discretized with rectangular elements, each having 28 degrees of freedom and 4 nodes, enabling accurate estimation of the MRE-based sandwich plate's vibration characteristics. An optimization problem based on the method of moving asymptotes (MMA), is subsequently formulated to identify the optimal topology of the MRE layer within the sandwich plate to minimize dynamic compliance yielding reduction in vibration amplitude. For material properties interpolation, an MRE-based penalization (MREP) model, based on solid isotropic material with penalization (SIMP) method, has been developed. To validate the accuracy of the proposed methodology, several numerical examples considering MRE-based sandwich plates under different loading and boundary conditions are provided. These examples illustrate the effectiveness of the proposed design optimization methodology for topology optimization of MRE-based sandwich panels to mitigate the vibration

Genotypic distribution of rotavirus strains causing severe gastroenteritis in children under 5 years old in Borazjan, Iran

Objective This study was conducted to evaluate the prevalence of rotavirus disease and to investigate the genotypes of rotavirus strains causing acute gastroenteritis among children aged <5 years old in Marvdasht, Iran. Methods One hundred and forty-one children, aged 1 month to 5 years, afflicted with severe diarrhea were enrolled during January 2007 to December 2008. Their stool samples were studied with enzyme immunoassays (EIA) for group A rotaviruses. Rotavirus-positive specimens were genotyped by the Nested RT-PCR using different types of specific primers. Findings Out of total collected samples rotavirus infection was detected in 40 (28.37%). Of the rotavirus episodes, 72.91% occurred during the first 2 years of life (P=0.038). The highest prevalence of infection was identified in summer (52.50%) and the lowest in winter (7.50%). The most common clinical features included diarrhea (96.25%), vomiting (82.50%) and fever (45.0%). Mixed genotypes were the predominant G type (60.0%), followed by non-typeable (12.50%), G2 (12.50%), G4 (10.0%) and G1 (5.0%) genotypes. G3/G8 mixed infection is the first of these rotavirus genotypes to be reported in Iran. Conclusion Regarding high frequency of rotavirus infection, continuous surveillance is needed to inform diarrhea prevention programs as well as to provide information about the occurrence of new rotavirus strains. This will assist policy makers in decision making on rotavirus vaccine introduction. Keywords: Rotavirus, Gastroenteritis, Genotyping, Children, Epidemiolog

On crack detection in curved beams using change of natural frequency

In this study, an inverse method for the purpose of identifying the parameters of a single-edge crack in a curved beam is investigated. This method requires both numerical and experimental natural frequencies. The differential quadrature element method (DQEM) is introduced to get the numerical ones. For the purpose of implementing the DQEM the beam is divided into some elements and the governing equations, the continuity and the boundary conditions, are exerted on these elements to create an eigenvalue problem which is solved to obtain the required frequencies. A rotational spring whose stiffness is a function of crack depth is used to model the crack. An objective function with the variables of crack location and depth which is the weighted mean squared error between experimental and numerical frequencies is defined. The artificial bee colony algorithm (ABC) an optimization algorithm inspired by the natural foraging behavior of honeybees is used to minimize the aforementioned objective function and obtain crack parameters. To investigate the accuracy of this non-destructive, fast and easy method, an experimental modal analysis test is conducted on a cracked beam. The results indicate that the position and depth of the crack can be determined successfully using this method. This test is done five times with a different crack depth each time, to show the efficiency of the method for all cracks even small ones. A brief investigation is also done on the effect of crack location and depth on the natural frequencies

A Neglected Case of Wilson’s Disease Presenting as Symptomatic Urolithiasis and Proteinuria: A Case Report and Review of the Literature

We report a short-statured, 39-year-old male presenting with recurrent kidney stones, history of refractory rickets, and bone deformity. He had been consuming multiple doses of calcium supplements and multiple courses of vitamin D over past 30 years before prior to reporting in our clinic without any significant laboratory or clinical improvement. The patient was diagnosed as having Fanconi’s syndrome attributable to Wilson’s disease. This patient highlighted that in case of resistant rickets, a high index of uncertainty must be invoked for Wilson’s disease. Appropriate timely recognition of this entity results in prompt ministrations and prevention of disability. We also presented and discussed reviews on Wilson’s disease from literature

Cytotoxicity Evaluation of Iranian Propolis and Calcium Hydroxide on Dental Pulp Fibroblasts

Abstract Background and aims. Since intracanal medicaments can affect the cell viability in periapical tissues, the aim of this study was to evaluate the effect of calcium hydroxide and propolis on pulp fibroblasts. Materials and methods. Two healthy third molars were used as a source to obtain fibroblasts. The fibroblasts were cultured and subjected to 1 mg/mL of propolis and calcium hydroxide. This experiment was performed in six replicates and cell viability was evaluated with MTT assay. Statistical analysis was performed by t-test. Results. Comparison of cell viability with the use of 1 mg/mL of calcium hydroxide and propolis showed that cells subjected to propolis were more viable when compared to calcium hydroxide (P < 0.05). Conclusion. In this study, calcium hydroxide reduced fibroblast viability, significantly more than Iranian propolis. Other properties should be evaluated before Iranian propolis could be indicated for use as intracanal medicament

The role of PECVD hard coatings on the performance of industrial tools

The advantages of the application of hard coatings, which are well knownfor cutting tools, are to a much lesser extent explored for casting, extrusion, molding and forming tools. Increasing the lifetime of these tools is an important task in surface engineering because of complex loading conditionsand often complicated tool geometry. The plasma-enhanced chemical vapor deposition (PECVD) technique is well suited to deposit hard coatings onto large dies and moulds. The aim of this study was to discuss deposition processes suitable for coating of the often large three-dimensional molds and dies used in metal forming. Furthermore, results obtained using different hard coatings in industrial applications for several case studies like aluminum pressure die-casting; plastics injection molding and sheet metal forming are presented and discussed. For best coating performance, a careful optimization of both substrate pretreatment and coating deposition is necessary. The plasma-enhanced chemical vapor deposition (PECVD) technique shows advantages for these applications because of the high flexibility in pre-treatment using chemical etching and plasma-nitriding, because of its ability to coat large complexly shaped tools and because of the possibility of deposition of low-chlorine containing low-friction coatings.  http://dx.doi.org/10.5937/metmateng1401015