Formulation, Development and Evaluation of Bilayer Floating Tablets of Antihypertensive Drug Bosentan

Hypertension, or high blood pressure, is a major public health concern around the world because of its large contribution to the global health burden and its function as a major risk factor for a variety of disease processes. Bosentan SR Floating Bilayer Tablets were made with HPMC K4M, HPMC E-15, and HPMC E-15 alone (80%) and in combination with varying percentages of polymer (20&60 percent, 40&40 percent, and 60&20 percent ). The hydrophilic polymer HPMC is used to make three different formulations (M4, M8, and M12) of floating Bosentan SR tablets, each with a viscosity grade of 80 percent. M12 formulation was shown to be suitable for SR tablet formulation. From the M12 formulation. It's based on the M12 formula. The fraction of high viscosity polymer can be lowered by adding low viscosity polymer, as demonstrated in the C3 formulation. It was clear from the dissolution profile of formulation C3 that by mixing the low and high viscosity polymers, the drug release from the formulation may be improved as compared to manufacturing M12 high viscosity polymer alone. According to the findings of this investigation, as floating duration increases, the release rate drops. As a result, it's appropriate for long-term formulation. Keywords: Bosentan, Floating Bilayer Tablets, Hypertension, SR Tablets, HPMC K4M, E-15

Assessing the Potential Replacement of Mineral Oil with Environmentally Acceptable Lubricants in a Stern Tube Bearing: An Experimental Analysis of Bearing Performance

This study compares the performance of a plain bearing, with a similar structure to a tail shaft stern bearing, lubricated with either mineral oil or an environmentally acceptable lubricant (EAL). The main characteristic of the bearing is its length/diameter ratio of <1. Measurements are carried out with the bearing operating under loads from 0.5 to 1 MPa and seven speeds ranging from 1 to 11 rev/s. The bearing lubricated with either mineral oil with a viscosity grade of 100 or an environmentally acceptable lubricant (EAL) with a viscosity grade of 100 or 150 is investigated according to the ISO standard. Bearing wear is simulated by increasing the clearance circle by 0.1 mm. According to the results obtained, the use of an EAL in place of mineral oil does not cause significant changes in the bearing performance, regardless of the value of the clearance radius. The pressure distribution in the oil film, bearing load carrying capacity, eccentricity and friction coefficient have similar values for the entire load and speed ranges considered, and the discrepancies in the results are within the range of the measurement errors. Only an increase in EAL viscosity causes significant changes in bearing performance and these changes comply with the general theory of lubrication.

Investigating the influence of carbon nanotube on the performance of asphalt binder

The purpose of this study aims at investigating the impact of multi-walled carbon nanotubes (MWCNT’s) on the properties of low viscosity grade asphalt binder. Asphalt binder with viscosity grade-10 is selected as the control binder and later it is modified with different percentages of MWCNT’s (0.5–2.5%). Penetration, softening point, ductility and rotational viscosity test were employed for evaluating the effect of MWCNT’s on basic physical properties of modified asphalt binder. Dynamic Shear Rheometer (DSR) is used for evaluating the rheological properties of the base and modified bitumen, for both aged and unaged bitumen. Based on the conventional and basic rheological tests, it was seen that the addition of MWCNT’s improved the high-temperature performance of modified bitumen. Multiple Stress Creep and Recovery (MSCR) test results revealed that the addition of MWCNT’s improved the creep and recovery of modified binders for both stress intensities (0.1 kPa and 3.2 kPa) which confirms that the modified binder is more rut resistant. Moreover, it was observed that there was a significant improvement in the aging resistance of the asphalt binder due to addition of MWCNTs. However low temperature performance of MWCNTs was not encouraging. Also, MWCNTs addition to asphalt binder was found to be stable under high-temperature storage condition. Overall, there is a significant amount of improvement using MWCNTs in the base asphalt binder.

Non-combustible, optically transparent polycarbonate compositions

A brief review of the results of research on reducing the flammability of modified materials based on polycarbonate, the effect of flame retardants and additives that reduce dropping, as well as affecting the complex of properties of polycarbonate is presented. The optimal concentrations of modifying additives for obtaining fire-resistant compositions with high optical characteristics have been determined. It is shown that to achieve the maximum flammability category (PV-0 at a thickness of 2 mm) and oxygen index (42.3%) for thin-walled products, it is necessary to use a high- viscosity grade of polycarbonate (MFI 2.5±1.0 g/10 min), alkali metal sulfonates as a fire retardant and an anti-dripping additive.

Experimental Investigation of the Viscosity Parameters Ranges—Case Study of Engine Oils in the Selected Viscosity Grade

The primary objective of the research was to compare the viscosity parameters of the same viscosity grade engine oils, as declared by the manufacturers, to the actual laboratory measurements. The secondary objective was to briefly investigate (1) what kind of information oil manufacturers provide in the product data sheets of the studied oils, and (2) the potential savings resulting from the use of the energy efficient oils. The study material consisted of 42 selected synthetic engine oils that belong to the 5W-30 viscosity grade. Stabinger SVM 3001 viscometer was used to determine kinematic viscosity at −20 °C, 40 °C, 100 °C and 130 °C. The HTHS (high temperature high shear), CCS (cold cranking simulator), FTIR (Fourier-transform infrared spectroscopy) and GC (Gas Chromatography) measurements were also performed for the samples that had the lowest and the highest kinematic viscosity. Large differences (5–25%) between oil producers’ declarations and the results of laboratory tests were found. Although all of the engine oils tested met the 5W-30 grade standards, the high variability of viscosity measurements needs to be reported. The difference between the oil with the highest and the oil with the lowest kinematic viscosity at −20 °C was 11,804 mm2/s. The outlying temperature-related viscosity profiles were recovered using Mahalanobis distances which identified 16 out of 42 analyzed oil samples as atypical.

Development of Floating Tablets of Metformin HCl by Thermoplastic Granulation. Part II: In Vitro Evaluation of the Combined Effect of Acacia Gum/HPMC on Biopharmaceutical Performances

Purpose: The aim of this study was to evaluate the combined effect, acacia gum(AG)/ hydroxypropylmethylcellulose (HPMC), on biopharmaceutical performances of floating tablets of metformin hydrochloride (MTH) prepared by thermoplastic granulation using stearic acid. Methods: We have prepared the matrixes using AG/HPMC as a polymer combination. This combination of polymers which represents 15% of the total mass of tablet was used at various ratios 3:1, 1:1, 1:3, with two viscosity grade of HPMC (k15M and k100M). The developed matrixes have been evaluated for their pharmacotechnical and biopharmaceutical properties. Results: In addition to the satisfactory physical characteristics of matrixes, it was revealed that the Fc3 and Fc6 formulations with AG/HPMC k15M and AG/HPMC k100M respectively, at ratio, 1:3 were considered the most performance. These formulations have shown swelling, fast flotation, 360 and 480 seconds respectively, and remained floating on the surface of the medium for more than 24 hours, with the matrix integrity, while F1, containing only AG, did not show swelling and did not float. In addition, extended in vitro release (>8 hours) with decreased dissolved MTH rates was demonstrated for Fc3 and Fc6 matrixes, 95% and 91% respectively, compared to F1 where MTH dissolution was complete after 2 hours. The drug release from the highest-performance matrixes (Fc3 and Fc6) was found to follow Korsmeyer-Peppas’s model. The mechanism drug release was controlled by diffusion and erosion. Conclusion: The AG/HPMC combination was suitable as a polymer matrix to improve the in vitro biopharmaceutical properties of MTH compared to AG.

THE EVALUATION OF TRIBOLOGICAL PROPERTIES OF MINERAL OILS-R600a REFRIGERANT MIXTURES UNDER STARVED LUBRICATION CONDITIONS

In refrigeration compressors, the amount of oil in tribocontacts in certain situations may be insufficient. In this case, poor lubrication conditions may occur. There may also be a situation in which the areas of lubrication lack lubricant and the lubrication of the friction pairs will be carried out by only the refrigerant. The requirements related to legal regulations and concerning refrigerants result in the return to the use of natural substances such as hydrocarbons. These substances do not contribute to the enlargement of the ozone hole and the greenhouse effect. The most commonly used refrigerant in the group of low-capacity devices is R600a (isobutene). The article verifies the test method allowing one to assess lubricity properties of oils for refrigeration compressors in the mixture with a refrigerant under the conditions of poor lubrication. The article also contains the results of wear tests which allow one to assess and contrast lubricity properties of oil–refrigerant mixtures for three mineral oils of the same viscosity grade under the conditions of poor lubrication in cooperation with R600a. The tests were performed for the air, R600a, mineral oils, and oil–refrigerant mixtures.