Patient’s compliance can be enhanced by using extended release drug delivery systems which allow decreasing the number of daily doses, and helping to maintain uniform drug levels and increase the safety margin for high-potency drugs. Hydroxypropyl methylcellulose (HPMC) is the most commonly used hydrophilic polymer for the preparation of oral controlled drug delivery systems. This research was conducted with the aim of developing matrix based oral controlled release tablets for the drug diclofenac sodium using different viscosity grades of HPMC (K15M) and to compare the drug release characteristics with those of a commercial product, Voltaren® SR 100. Similarity factor (f2), values in between test formulation and marketed preparation was calculated to choose the best formulation. The release kinetics from various matrices was also studied. Increasing in polymer content reduced the rate of drug release. At the same polymer content in the matrix, the drug release was most sustained with tablets prepared using HPMC (K15M). Out of all the formulations studies, matrix tablets containing 40% of HPMC (K15M) showed comparable dissolution profile to that of the marketed preparation as indicated by a similarity factor value of (f2) 88.30%. The release of drug from marketed preparation and matrix with HPMC (K15M) 40% was found to be a diffusion drug mechanism as per Higuchi equation.
Summary Recently, many countries have decided to reopen gradually and some of them have thought that social distancing has not had a significant effect. In our study, a new view of the importance of social distancing to prevent the spread of coronavirus has been presented in terms of the relationship between peak day and peak period and population density of nine countries. Data for nine different countries in different coronavirus situations have been analyzed. The analysis process was applied by using three programs, namely; WebPlotDigitizer, WSxM and Origin. The results provide evidence of the effectiveness of social distancing by calculation of the effect of population density on coronavirus infection. That was applied by two stages, the first one by determination of two different groups of countries depending on the rate and range of coronavirus spread. These two groups were countries with developed and developing COVID19 which lead to calculate the peak day and the period times of developed groups. Then, analysis of that data with population density was evaluated to indicate there are significant effects of population density on peak day and peak period times which explain the importance of social distancing between people to manage and control that. The results showed that there are increasing in peak day and peak period times with increasing the population density.
In this work, a series of Natural Rubber (NR)/Styrene Butadiene Rubber (SBR) blends were formulated to protect metallic petrochemical storage tanks from corrosive media. Therefore, these blends tested against a 10% HCl solution for 72 hr at room temperature. Blends series were prepared with different ratios of NR/SBR; 25/75, 30/70, 35/65, 40/60, 45/55, 50/50, and 55/45. Three types of carbon black (N-330, N-660, and N-762) were added individually to the 45/55 blend. Hardness, tensile strength, modulus, and elongation properties were tested before and after immersion in the 10% HCl attack media. All these mechanical properties decreased after immersion action accept hardness property. Up to 45 phr NR content, the hardness increased linearly independent on immersion action, but HCl immersion gives higher hardness values. Tensile strength increased up to 40 phr NR content with and without immersion and the immersion action decreased tensile values. The highest elongation value obtained with 35/65 blend with and without immersion. The 45 phr NR content gives the higher modulus, while the lowest value obtained with the 30 phhr content. For 45/55 blend, the hardness increased as the carbon black particle size decreased and immersion action gives higher hardness values. The tensile strength decreased linearly with the carbon black surface area, while with the medium surface area, the highest modulus and lowest elongation obtained.
Rheological properties investigation of polymer solution with inorganic nanoparticles aqueous mixtures were studied. In the present work, Polyvinyl Acetate (PVAc) was used in a form aqueous solution, while titanium dioxide nanoparticles (TiO 2 ) was used as an inorganic additive. PVAc was loaded with 0, 0.5, 1, 2, 3, and 4 weight percent (wt. %) of TiO 2 nanoparticles, where the maximum concentration of TiO 2 was 4 wt. % that gives the enough information about the behaviour. Cone on plate Rheometer was applied to measure rheological characteristics of PVAc/TiO 2 mixture flow at different shear rates, while Tensometer, pH meter, and Densitometer were used to peer understanding of flow mechanisms. The results were shown a significant change in shear stressshear rate behavior with the TiO 2 ratio increasing, especially at 2-3 wt. %. The shear stress decreasing with the shear rate increases. The viscosity tends to decrease with the high shear rate values about 1.14-1.3 s-1 in low concentration of TiO 2 nanoparticles about 0.5 wt. %. The pH and surface tension values show an interesting decreasing overall range of PVAc/TiO 2 nanoparticles. These results have an important effect on processing and capability production in polymer composites technology, as well as energy conception in polymer and composite technology of PVAc/TiO 2 nanoparticles composite.
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