Enhancement of solubility and bioavailability of ambrisentan by solid dispersion using Daucus carota as a drug carrier: formulation,characterization, in vitro,and in vivo study

Ambrisentan is an US FDA approved drug, it is the second oral endothelin A receptor antagonist known for the treatment of pulmonary arterial hypertension, but its oral administration is limited due to its poor water solubility. Hence, the objective of the investigation was focused on enhancement of solubility and bioavailability of ambrisentan by solid dispersion technique using natural Daucus carota extract as drug carrier. Drug carrier was evaluated for solubility, swelling index, viscosity, angle of repose, hydration capacity, and acute toxicity test (LD₅₀). Ambrisentan was studied for the saturation solubility, phase solubility, and Gibbs free energy change. Compatibility of drug and the natural carrier was confirmed by DSC, FTIR, and XRD. Solid dispersions were evaluated for drug content, solubility, morphology, in vitro, and in vivo study. Screening of the natural carrier showed the desirable properties like water solubility, less swelling index, less viscosity, and acute toxicity study revealed no any clinical symptoms of toxicity. Drug and carrier interaction study confirmed the compatibility to consider its use in the formulation. Formed particles were found to be spherical with smooth surface. In vitro studies revealed higher drug release from the solid dispersion than that of the physical mixture. Bioavailability study confirms the increased absorption and bioavailability by oral administration of solid dispersion. Hence, it can be concluded that the natural Daucus carota extract can be the better alternative source for the preparation of solid dispersion and/or other dosage forms for improving solubility and bioavailability.     

A facile co-precipitation synthesis of heterostructured ZrO<Subscript>2</Subscript>|ZnO nanoparticles as efficient photocatalysts for wastewater treatment

ZrO₂-decorated ZnO (ZrO₂|ZnO) nanoparticles (NPs) have been synthesized by a facile co-precipitation method in the presence of cetyltrimethylammonium bromide (CTAB) surfactant. The ZrO₂ amount in the NPs has been varied from 1.0, 2.0, 4.9, to 9.3% by weight. The resulting NPs are heterostructured and consist of a crystalline ZnO core (wurtzite phase) surrounded by an amorphous ZrO₂ layer. X-ray diffraction analyses support this observation. The NPs show a narrow size distribution and are slightly elongated. Compared to pure ZnO NPs, the hybrid ZrO₂|ZnO ones show enhanced photocatalytic activity toward the degradation of Rhodamine B under UV–Vis light. Such enhancement has been partly attributed to the increased amount of oxygen vacancies when ZrO₂ is incorporated into the NPs, as shown by X-ray photoelectron spectroscopy analyses.     

Effect of Mg2+ ions substitution on phase formation,structural, morphological,and optical properties of Zn0.1−xMgxO structure

Journal of Materials Science: Materials in Electronics - In the present research work, Mg-doped zinc oxide Zn0.1?xMgxO (For x?=?0.000, 0.002, 0.006, 0.010) nanoparticles were...     

Interfacial Behaviour of Complex Hydrocarbon Fluids at Elevated Pressures and Temperatures

Interfacial tension is unique in the sense that it relates to the interface between two immiscible fluid phases. Hence, interfacial tension between the fluid phases can be used to infer a great deal of information about phase equilibria such as solubility, miscibility and mass transfer interactions between the two bulk fluid phases in contact. In this paper, we examine the utility of interfacial tension to characterize miscibility and mass transfer mechanisms in complex hydrocarbon fluids at elevated pressures and temperatures. This study also provides a new method to estimate the dynamic interfacial tension and miscibility by incorporating counter‐directional diffusivities into the traditional Parachor model.     

Formulae for determining heterodyne system spurious frequencies that coincide with desired output frequency

In this paper, formulae to determine the lowest order and other higher order spurious frequencies that coincide with desired output signal frequencies of mixers have been derived. The proposed formulae give general expressions that are suitable for any order of heterodyne mixing. The formulae have been verified using a suitable example and compared with the simulation results obtained through the radio frequency simulation software of Advanced Design System. The formulae directly reveal the order of the troublesome spurious frequencies that the designers would encounter in heterodyne systems. In comparison with these direct formulae, the results of existing spurious analysis software are based on the maximum order of simulation carried out. Based on these simulations, the coinciding spurious components have to be manually sorted out. Proposed formulae are quick tools used by the microwave system and circuit designers for choosing and finalizing heterodyne frequencies in their designs without the need for any simulations.     

Structural and Electrical Properties of Ag/<Emphasis Type="Italic">n</Emphasis>-TiO<Subscript>2</Subscript>/<Emphasis Type="Italic">p</Emphasis>-Si/Al Heterostructure Fabricated by Pulsed Laser Deposition Technique

We have investigated the structural and electrical characteristics of the Ag/n-TiO₂/p-Si/Al heterostructure. Thin films of pure TiO₂ were deposited on p-type silicon (100) by optimized pulsed laser ablation with a KrF-excimer laser in an oxygen-controlled environment. X-ray diffraction analysis showed the formation of crystalline TiO₂ film having a tetragonal texture with a strong (210) plane as the preferred direction. High purity aluminium and silver metals were deposited to obtain ohmic contacts on p-Si and n-TiO₂, respectively. The current–voltage (I–V) characteristics of the fabricated heterostructure were studied by using thermionic emission diffusion mechanism over the temperature range of 80–300 K. Parameters such as barrier height and ideality factor were derived from the measured I–V data of the heterostructure. The detailed analysis of I–V measurements revealed good rectifying behavior in the inhomogeneous Ag/n-TiO₂/p-Si(100)/Al heterostructure. The variations of barrier height and ideality factor with temperature and the non-linearity of the activation energy plot confirmed that barrier heights at the interface follow Gaussian distributions. The value of Richardson’s constant was found to be 6.73 × 10⁵ Am^?2 K^?2, which is of the order of the theoretical value 3.2 × 10⁵ Am^?2 K^?2. The capacitance–voltage (C–V) measurements of the heterostructure were investigated as a function of temperature. The frequency dependence (Mott–Schottky plot) of the C–V characteristics was also studied. These measurements indicate the occurrence of a built-in barrier and impurity concentration in TiO₂ film. The optical studies were also performed using a UV–Vis spectrophotometer. The optical band gap energy of TiO₂ films was found to be 3.60 eV.     

Solar thermal modelling of a building with a roof pond and ventilation control systems

The paper proposes and presents thermal modelling of a ventilation-controlled, non-air-conditioned building with evaporative cooling (e.g. open water pond) over the roof for passive solar air conditioning. The ventilation rate, expressed in terms of number of air changes per hour, is assumed to be time-dependent, as should be the case in normal practice. A self-consistent periodic heat transfer analysis for a non-air-conditioned building with roof cooling and ventilation control systems, furnishing (assumed isothermal mass), windows, door and basement ground heat storage effects has been developed to assess the feasibility of the proposed passive space air-conditioning. It is shown that for no-ventilation summer nights the inside air temperature remains higher than the ambient air temperature even with an effective roof cooling system, and hence the windows should be opened to lose the internal heat and to introduce cool and fresh outside air. It is found that for a ventilation-controlled building with a roof pond the passive solar air conditioning can be achieved more effectively.     

Catalytic oxidation of butyl acetate over silver-loaded zeolites

The performance of silver-loaded zeolite (HY and HZSM-5) catalysts in the oxidation of butyl acetate as a model volatile organic compound (VOC) was studied. The objective was to find a catalyst with superior activity, selectivity towards deep oxidation product and stability. The catalyst activity was measured under excess oxygen condition in a packed bed reactor operated at gas hourly space velocity (GHSV)=15,000-32,000 h(-1), reaction temperature between 150 and 500 degrees C and butyl acetate inlet concentration of 1000-4000 ppm. Both AgY and AgZSM-5 catalysts exhibited high activity in the oxidation of butyl acetate. Despite lower silver content, AgY showed better activity, attributed to better metal dispersion, surface characteristics and acidity, and its pore system. Total conversion of butyl acetate was achieved at above 400 degrees C. The oxidation of butyl acetate followed a simple power law model. The reaction orders, n and m were evaluated under differential mode by varying the VOC partial pressure between 0.004 and 0.018 atm and partial pressure of oxygen between 0.05 and 0.20 atm. The reaction rate was independent of oxygen concentration and single order with respect to VOC concentration. The activation energies were 19.78 kJ/mol for AgY and 32.26 kJ/mol for AgZSM-5, respectively.     

Magnetic properties of Ni-NiO (ferromagnetic-antiferromagnetic) nanocomposites obtained from a partial mechanochemical reduction of NiO

The magnetic properties of ferromagnetic (FM)-antiferromagnetic (AFM), Ni-NiO, nanocomposites obtained from a reactive ball milling reduction of NiO in H2 atmosphere have been studied. The formation of ferromagnetic Ni from antiferromagnetic NiO can be accurately followed by the increase of the saturation magnetization. The microstructure of the nanocomposite, consisting of FM Ni nanoparticles embedded in an AFM NiO matrix leads to exchange bias effects, i.e., loop shifts and coercivity enhancement, after field cooling from above the Néel temperature of NiO.     

Dynamic Fracture and Strain Rate Behavior of Aggregates Used in Transportation

The static and dynamic uniaxial compressive strengths of coarse aggregate materials used in portland cement concrete (PCC) were determined under dry and saturated conditions for three blast furnace slags, three limestones, four dolomites, and two mafic igneous rocks. The slag aggregates exhibited the lowest compressive strength, followed by the carbonates (limestones and dolomites), and the mafic igneous rocks. Both the dry and saturated aggregates revealed a higher compressive strength under dynamic loads compared to the static loads. Based on the experimental data, a rate sensitivity parameter was defined to describe the increase in compressive strength as a function of strain rate. This parameter is deemed to have considerable relevance in evaluating the ability of a specific aggregate to resist dynamic loads such as in aggregate interlock in PCC cracks and joints, friction in asphalt, and also in the development of microfracture during rock blasting. Comparison of the compressive strength data to density and LA abrasion values revealed that the dynamic data have a better correlation to the above properties than the static data.