Safety is one of the most critical issues in any test. The flexural test is a significant one to obtain material specifications. In this paper, a standard sample dose rate was calculated for the graphite flexural test in Tehran research reactor. Using different standards, the dose was computed at different distances and two periods of radiation, 15-40 days. Our calculations were performed with the ORIGEN and MCNPX codes. The impurity amounts of the material were measured by two methods of X-ray Fluorescence (XRF) and Inductively Coupled Plasma, Atomic Emission Spectroscopy (ICP-AES). The obtained results show that the Claiborne & Trubey standard is more stringent than other standards, and it has less than 2 μ Sv/h dose with the observance of 100cm distance and 20 days after irradiation. Moreover, calculations of the transfer chamber indicate that there is no limitation for the transport of the samples. Finally, it can be concluded that the considered method of this research can be used also for other materials at the reactor core.

Several full porcelain systems are available in the market, among which In - Ceram (Vita Zahnfabrik, Bad Sackingen, Germany), has been introduced to show unique properties including: fine esthetic and high quality strength. In this investigation Flexural Strength of In - Ceram core material has been evaluated by four - point bending test with Instron (Model 1195) machine. Samples were provided in form of ten bars of core material with the dimension of 30 × 6 × 2.5 mm.Results obtained show that the mean value of 538 ± 42 (MPa), of force is required to hit its resistance limit which is higher than similar values in other dental ceramics, within acceptable clinical range.

Flexural strength test has a significant effect on the determination of failure strengths and cracking moment. According to ASTM-C78, the size and shape of used specimens were cubes by size (700*150*150 mm). Here, the efficiency of the non-destructive Break-Off (BO) and flexural strength tests was investigated for assessing the in-place compressive strength of steel fiber reinforced concrete (SFRC). In order to provide a thorough and comprehensive database, 24 mixtures were designed with various cement content, maximum aggregate size, steel fibre volume fractions and the constant water/ cement ratio of 0.4 for all mixtures. Then, effective parameters of SFRC and Break-Off and flexural strength test results were evaluated. The studies showed that volumetric percentage and features of steel fibers had a significant influence on concrete properties as well as Break-Off and flexural strength test results. According to the experimental results it could be generally concluded that the influencing factors, namely, SFRC properties due to presence of steel fibers and non-destructive tests significantly affect the results as follows: Generally, for a constant W/C ratio, it can be concluded that raising the cement content increases the mean values of Break-Off strength and Flexural strength. It can be stated that increasing the size of the aggregate causes an increase in strength. Also, the steel fibers restrain the development of internal micro-cracks in the concrete and thus contribute to the increase in bending strength, which causes improving Break-Off and flexural strengths. In addition, the conventional numerical regression model was developed in this study. Statistical indices were used to compare the efficiency and accuracy of the model. The result of this study confirmed the accuracy of the artificial neural network models in the determination of the compressive strength of concrete.

In many applications, viscoelastic properties of reinforced composites need to be determined prior to their real service life. Such properties can be assured by destructive and non-destructive tests. In this paper, a novel non-destructive test (NDT) method based on flexural free vibration is introduced to investigate the viscoelastic properties of fiber-reinforced composites. Three different types of industrial fibers (carbon, glass, and hemp) and an unsaturated polyester resin were selected to produce bar-shaped composites via pultrusion technique. These composite bars were used in a simple NDT method which just required a wooden hammer, two elastic jaws, a microphone and a recorder software program to perform the experiment. The composite bars were mounted on elastic jaws and hit by a wooden hammer at one end of the specimen as a perpendicular impulse. The produced sound at the other side of the bars was recorded. By analyzing the recorded sounds by means of fast Fourier transform (FFT), viscoelastic properties such as flexural elastic modulus and the loss parameter (Tan d) were calculated for the fiber-reinforced composites. For determination of flexural elastic modulus, the first three modes of vibration in FFT graphs were analyzed using Temuschenco theory. Also, Tan d was determined by analyzing the drop in the intensity of vibrational energy as a function of time. Although there was a slight discrepancy between the calculated values from the NDT method and the actual data from dynamic mechanical thermal analysis (DMTA) approach, a good agreement was achieved between NDT and DMTA results.

Determining the dynamic properties of soils is an important issue in solving seismic geotechnical engineering problems. In this respect, several types of field and laboratory methods are available with different advantages and limitations regarding solving different problems. The difference between the results of in-site and laboratory tests is one of the engineers’ difficulties. Some reasons for the difference between the values ​​of dynamic parameters which achieved from field and laboratory tests, are the remolding effect of samples, difference in stress conditions and loss of cementation; negligence of these facts in soil dynamic properties may lead to serious damage due to unrealistic soil analysis. Among the laboratory methods, the resonant column test is one of the methods which determines the dynamic properties of soils at small strains. In this research, Young’s modulus and damping ratio of core barrel and reconstituted earth materials have been studied by performing resonant column test in flexural mode. The effects of confining pressure and anisotropic confining pressure was studied by using the Young’s modulus and damping ratio versus flexural strain diagrams. The results of the study indicate that reconstituting reduces the Young’s modulus, but the variation of damping ratio versus shear strain for core barrel and reconstituted samples is negligible. Increase in the confining pressure and anisotropic confining pressure result in the increase of Young’s modulus. Comparing the damping ratio results with the two methods of free vibration decay and half-power bandwidth indicates that the damping ratio values ​​obtained from the half-power bandwidth method are higher.

Introduction: Fracture of the denture base and its repair are one of the main concerns of patients with a complete denture. This is often due to patients’ carelessness in maintaining dentures, or a low strength and resistance of the acrylic resin. This study aimed to compare the fracture resistance of heat-cured, self-cured, and injectable acrylic resins using a three-point flexural test. Materials & Methods: In this experimental study, 30 blocks of acrylic resin (Ivoclar VivaDent-Liechtenstein), measuring 2. 5×25×50 mm, were prepared with three methods of heatcured ¸ self-cured, and injection. The samples were incubated for 24 hours to simulate the oral conditions. The samples were then subjected to three-point flexural testing in a universal testing machine. The force required for the failure of the samples was measured, and the results were compared and analyzed using Kruskal-Wallis and Wilcoxon tests with SPSS 22 (α = 0. 05). Results: Among the three samples, the fracture resistance of the self-cured acrylic resin was the lowest, and the fracture resistance of the injected acrylic resin was the highest. The differences in fracture resistance between the acrylic resins were significant (p value < 0. 001). Conclusion: Since the injected acrylic resin exhibited the highest fracture resistance, it is more appropriate for the fabrication of fracture-resistant dentures.

Producion of efficient antimicrobial drugs against to common human pathogens is one of the most important challenges in the field of medical microbiology. Continuous screening of clinical isolates and survey of antimicrobial resistance pattern is critical.Today, disk diffusion and dilution methods are known as the common antimicrobial susceptibility testing methods. Disk diffusion method does not render dependable results in determination of antimicrobial susceptibility pattern because this method is semi quantitative. MIC determination by microdilution and macrodilution techniques and recent method “E-Test”, have given interpretable results to researchers. Microdilution and macrodilution methods are also time consuming, expensive and error- prone methods. Whereas E-Test method is one of the means by which we will be able to determine susceptibility pattern of known species in low cost and short time. In this survey, constructing and printing of E-Test, coating of antibiotic on O.H.P film and quality control of constructed E-Tests were performed according to M7 A7 CLSI Standard. In this study quality of required materials for E-Test Production were suitable. Evaluation of constructed strips was performed using standard strain of staphylococcus aureus and reproducibly of results was appreciated.

Contact dermatitis is an inflammatory skin disease due to contact with different substances and caused by two mechanisms: allergy and irritation. Contact dermatitis is a common skin disease and the most common occupational dermatosis. Differentiating between allergic and irritant contact dermatitis is essential in the identification of etiologic factor(s) and hence, its control and prognosis. This differentiation can be done only by patch test. Unfortunately, this simple, safe and useful test is always neglected. We review the basics of patch test, the method of performance, reading and interpretation of its results, possible side effects and results of studies done with patch test in different countries.

Statement of Problem: Ceramic restorations are popular because they can provide the most natural replacement for teeth. However, the brittleness of ceramics is a primary disadvantage. There are various methods for strengthening ceramics such as metal framework, ceramic cores, and surface strengthening mechanisms through glazing, work hardening and ion exchange. Purpose: The purpose of this study was to evaluate the effect of polish on flexural strength of feldspathic porcelain and to compare it with overglaze and autoglaze. Materials and Methods: In this experimental study, one brand of feldspathic porcelain (colorlogic, Ceramco) was used and forty bars (25×6×3 mm) were prepared according to ISO 6872 and ADA No. 69. The specimens were randomly divided into four groups: overglazed, auto glazed, fine polish and coarse polish (clinic polish). Flexural strength of each specimen was determined by three point bending test (Universal Testing Machine, Zwick 1494, Germany). Collected data was analyzed by ANOVA and post-hoc test with P<0.05 as the limit of significance. Results: A significant difference was observed among the studied groups (P<0.0001). According to post-hoc test, flexural strength in overglaze and fine polish group were significantly stronger than clinic polish and autoglaze group (P<0.001). Although the mean value for overglazed group was higher than fine polish group, this was not statistically significant (P=0.9). Also no statistical difference was seen between autoglazed and coarse polish group (P=0.2). Conclusion: Based on the findings of this study, flexural strength achieved by fine polish (used in this study) can compete with overglazing the feldespathic porcelains. It also can be concluded that a final finishing procedure that involves fine polishing may be preferred to simple staining followed by self-glazing.