Search

A number of studies have reported on the mechanical properties of paper coatings and the influence of various parameters on cracking at the fold. Failure at the pigment-binder interface is important to understand because it likely controls how coating layers fail or crack in different applications and processes. In this study, a model system of a calcium carbonate surface in contact with latex and starch binders was used to evaluate the interfacial bonding performance affecting failure in tensile mode. Samples of calcium carbonate marbles with binder films between them were tested in tensile tests and the results were compared with those of pure binder films. In addition, contact angles of calcium carbonate, latex and starch were measured. The failed surfaces were analyzed using Raman spectroscopy and scanning electron microscopy (SEM). All sample involving the calcium carbonate surface failed at a maximum stress of around 25 % compared to that of pure films. Samples that contained starch exhibited larger maximum stress values than pure latex system. The strain at failure for these samples did not depend on the starch content to a large extent. While Raman results did not indicate any residual latex particles on the adhesively failed surfaces, SEM microscopy confirmed that at least part of the failure was still cohesive because regions of binder were present on the surface.

The mechanical properties of paper coating layers are important in various converting processes such as printing and folding of the paper. A method was developed to produce free-standing pigmented coating layers thick enough to be tested in bending as well as tension. The mechanical properties of these coating layers were characterized. Free-standing films with two types of binder formulations, pure latex or latex-starch combinations, with different binder content were prepared through an innovative film forming method that allows uniform drying of the coating layer while minimizing cracking. Tensile and flexural samples were cut out of these films. Tensile and flexural tests were carried out on samples and the results were compared. Tensile and flexural moduli were found to be similar. However, both stress at failure and strain at failure were higher in flexural tests compared to those in tensile tests. Three different types of paper were coated with these formulations and their failure during printing was evaluated through a standard ink picking test. Papers with different basis weights and porosities were found to have different picking resistance values. An interesting result was that the picking resistance did not correlate with the elastic modulus of the coating, but with the strain at failure behavior. This result indicates that the stiffness of the coating layer is not as critical during printing compared to its flexibility.

Background: This study was conducted on patients with tuberculosis (TB), based on regional needs and the outbreaks of the contagious disease, particularly those diagnosed with the smear-positive during 2014 - 2016. The regions neighboring this province, low health information, poorly equipped hospitals/medical clinics, high rate of welfare, the illegal entrance of foreigners to the province are necessities that have to be mentioned. Objectives: Spreading awareness of the disease in the province and the examination of possible ways to control and prevent its spreading are the purposes of this study. Methods: First, the information concerning the files of 250 patients with smear-positive pulmonary tuberculosis was collected in Zahedan’s Tuberculosis Coordinator and the diagnostic criterion for the studied participants was a microscopic observation of the sputum. All patients had a chest X-ray and were examined every two months by an infectious disease specialist who diagnosed them with smear-positive pulmonary tuberculosis. As the observations were incomplete, we could not apply the regular methods and SPSS software to estimate the survival probability (function); instead, we used Generalized Turnbull’s Estimator (GTE) and R software to calculate the non-parametric conditional probability of the patient’s survival and recovery times. For Instance, for the ith person, Li and Ri have been considered based on the last positive result and the first negative result of the disease, respectively. Results: Among 250 studied patients, four patients are right censored and the rest of them are interval censored. The patients’ age ranged from 10 to 91 years, the average age of diagnosis in infected males is 58.54 with a standard deviation (SD) of 19.10 years and females was 55.40 with an SD of 18.09 years. During this period there were no major differences between males and females. Moreover, 49.2% of the patients infected via sexual transmission were males and 50.8% of the patients were females. Conclusions: In this study, the patients’ weight was considered an effective variable in the evaluation of the survival function (the possibility of conditional survival) and we considered the effect of factors such as sex, the previous diagnosis of diabetes/AIDS, the previous history of being in contact with people with TB disease, and a history of imprisonment on the survival probability. As we can see, all the auxiliary variables mentioned above, are significantly effective in the course of the patient’s treatment and recovery (survival) time.

This study explores the effects of heat treatment on the microstructure and mechanical properties of explosively welded Ck60 steel/St37 steel. The objective is to find an economical way for manufacturing bimetallic plates that can be used in the rolling stand of hot rolling mill units. The explosive ratio and stand-off distance are set at 1.7 and 1.5t (t = flyer thickness), respectively. Since explosive welding is accompanied by such undesirable metallurgical effects as remarkable hardening, severe plastic deformation, and even formation of local melted zones near the interface, heat treatment is required to overcome or alleviate these adverse effects. For this purpose, the composites are subjected to heat treatment in a temperature range of 600-700 °C at a rate of 90 °C/h for 1 h. Results demonstrate well-bonded composite plates with a wavy interface. In the as-welded case, vortex zones are formed along the interface; however, they are transformed into fine grains upon heat treatment. Microhardness is also observed to be maximum near the interface in the welded case before it decreases with increasing temperature. Shear strength is the highest in the as-welded specimen, which later decreases as a result of heat treatment. Moreover, the energy absorbed by the heat-treated specimens is observed to increase with increasing temperature so that the lowest value of absorbed energy belongs to the as-welded specimen. Finally, fractography is carried out using the scanning electron microscope to examine the specimens subjected to shear and impact tests. As a result of heat treatment, fracture surfaces exhibit dimpled ruptures and fail in the mixed mode, while failure in the as-welded specimens predominantly occurs in the brittle mode.

This paper employs a back analysis method to determine soil strength parameters of the Mohr-Coulomb model from in situ geotechnical measurements. The lateral displacement of a soil nailed wall retaining an excavation in Tehran city used as a criterion for the back analysis. For this purpose, a genetic algorithm is applied as an optimization algorithm to minimize the error function, which can perform the back analysis process. When the accuracy of modeling is verified, the back analysis is performed automatically by creating a link between genetic algorithm in MATLAB and Abaqus software using Python programming language. This paper demonstrated that the genetic algorithm is a particularly suitable tool to determine 9 soil strength parameters simultaneously for 3 soil layers of the project site to decrease the difference of lateral displacement between the results of project monitoring and numerical analysis. The soil strength parameters have increased, with the most changes in Young's modulus of the first to third layers as the most effective parameter, 49.45%, 61.67% and 64.35% respectively. The results can be used in advanced engineering analyses and professional works.