The question about the existence of correlation between the parameters A and m of the Paris function is re-examined theoretically for brittle material such as alumina ceramic (Al2O3) with different grain size. Investigation about existence of the exponential function which fit a good approximation to the majority of experimental data of crack velocity versus stress intensity factor diagram. The rate theory of crack growth was applied for data of alumina ceramics samples in region I and making use of the values of the exponential function parameters the crack growth rate theory parameters were estimated.
The aim of this study is to propose mathematical expressions for estimation of the flexural strength of plain concrete members from ultrasonic pulse velocity (UPV) measurements. More than two hundred pieces of precast concrete kerb units were subjected to a scheduled test program. The tests were divided into two categories; non-destructive ultrasonic and bending or rupture tests. For each precast unit, direct and indirect (surface) ultrasonic pulses were subjected to the concrete media to measure their travel velocities. The results of the tests were monitored in two graphs so that two mathematical relationships can be drawn. Direct pulse velocity versus the flexural strength was given in the first relationship while the second equation des
... Show MoreThe aim of this study is to propose mathematical expressions for estimation of the flexural strength of plain concrete members from ultrasonic pulse velocity (UPV) measurements. More than two hundred
pieces of precast concrete kerb units were subjected to a scheduled test program. The tests were divided into two categories; non-destructive ultrasonic and bending or rupture tests. For each precast unit, direct and indirect (surface) ultrasonic pulses were subjected to the concrete media to measure their travel velocities. The results of the tests were mointered in two graphs so that two mathematical relationships can be drawn. Direct pulse velocity versus the flexural strength was given in the first relationship while the second equati
Design of experiments (DOE) was made by Minitab software for the study of three factors used in the precipitation process of the Sodium Aluminate solution prepared from digestion of α-Al2O3 to determine the optimum conditions to a produce Boehmite which is used in production of ɤ-Al2O3 during drying and calcination processes, the factors are; the temperature of the sodium aluminate solution, concentration of HCl acid added for the precipitation and the pH of the solution at which the precipitation was ended. The design of the experiments leads to 18 experiments.
The results show that the optimum conditions for the precipitation of the sodium aluminate solution which
... Show MoreCeramic to metal joining technique, which was used in this investigation includes the use of active filler alloy as a sandwich between the alumina and kovar alloy for brazing. High purity powdered metals of silver, copper, and additives of titanium were used to prepare the active filler alloy, through compacting the mixed powders and alloying in a furnace with argon atmosphere at the temperature of 800oC for 10 minutes. To use it as an active filler metal, it has been modified to a proper thickness. Two groups of alumina were prepared with different sintering temperatures (1450oC and 1650oC) and each group was tested under atmospheric pressure, vacuum furnace pressure of 2*10-4 torr and vacuum furnace pressure of 2*10-6 torr. All the pro
... Show MoreBackground: According to several animal and human studies, Vitamin D appears to play a substantial role in the development of diabetic nephropathy, However, the possibility of vitamin D's Reno protective impact and influence on the reversal of already-existing renal damage remains speculative. Vitamin D deficiency and insufficiency are ubiquitous worldwide and have been linked to a variety of pathophysiological conditions, including diabetes, allergies, autoimmune illnesses, pregnancy difficulties, and, more recently, worse COVID-19 clinical outcomes. From a translational perspective, the goal of this review is to look into the potential function of vitamin D in the development of diabetic kidney diseases
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In past years, structural pavement solution has been combined with destructive testing; these destructive methods are being replaced by non-destructive testing methods (NDT). Because the destructive test causes damage due to coring conducted for testing and also the difficulty of adequately repairing the core position in the field. Ultrasonic pulse velocity was used to evaluate the strength and volumetric properties of asphalt concrete, of binder course. The impact of moisture damage and testing temperature on pulse velocity has also been studied. Data were analyzed and modeled. It was found that using non-destructive testing represented by pulse velocity could be useful to predict the quality of asphalt c
... Show MoreA potential alternative energy resource to meet energy demands is the vast amount of gas stored in hydrate reserves. However, major challenges in terms of exploration and production surround profitable and effective exploitation of these reserves. The measurement of acoustic velocity is a useful method for exploration of gas hydrate reserves and can be an efficient method to characterize the hydrate-bearing sediments. In this study, the compressional wave velocity (P-wave velocity) of consolidated sediments (Bentheimer) with and without tetrahydrofuran hydrate-bearing pore fillings were measured using the pulse transmission method. The study has found that the P-wave velocity of consolidated sediments increase with increasing hydrate format
... Show MoreThe patent means that the inventor is granted a right of intellectual property that is solely acquired by the patent's owner. This study highlights the compulsory licensing provisions that entitle government agencies to exploit the inventor's patent and to exploit it in the manufacture of goods and industries by a third party without the consent of the patent owner for reasons required by the interest of society.
This means has been referred to by Decree-Law No. 11 of 2021 on the regulation and protection of industrial property rights. However, the UAE legislator has made recourse to this means an exception, restricting this means by justification required by the public interest of society.
The study will focus on the des
... Show MoreOsteopontin hormone (OPN) is an extracellular matrix protein that is expressed in bone cells such as osteoblasts and osteoclasts and associated with bone turnover and bone mineral density (BMD) in postmenopausal women with osteoporosis.
The aim of the study is to investigate serum levels of circulating OPN and its relationship with biochemical parameters and BMD in postmenopausal women with osteoporosis in Iraq. Serum samples from fifty postmenopausal women were selected from patients attending two educational hospitals in Baghdad, which are AL Wasity Educational Hospital and Baghdad Educational Hospital, during the period from November 2018 to March 2019. Twenty five postmenopausal healthy women were inc
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