Enhanced stability and permeation potential of nanoemulsion containing sefsol-218 oil for topical delivery of amphotericin B

Aim: To characterize the enhanced stability and permeation potential of amphotericin B nanoemulsion comprising sefsol-218 oil at varying pH and temperature of aqueous continuous phase.

Methodology: Several batches of amphotericin B loaded nanoemulsion were prepared and evaluated for their physical and chemical stability at different pH and temperature. Also, a comparative study of ex vivo drug permeation across the albino rat skin was investigated with commercial Fungisome® and drug solution at 37?°C for 24?h. The extent of drug penetrated through the rat skin was thereby evaluated using the confocal laser scanning microscopy (CLSM).

Results and conclusions: The optimized nanoemulsion demonstrated the highest flux rate 17.85?±?0.5?µg/cm²/h than drug solution (5.37?±?0.01?µg/cm²/h) and Fungisome® (7.97?±?0.01?µg/cm²/h). Ex vivo drug penetration mechanism from the developed formulations at pH 6.8 and pH 7.4 of aqueous phase pH using the CLSM revealed enhanced penetration. Ex vivo drug penetration studies of developed formulation comprising of CLSM revealed enhanced penetration in aqueous phase at pH 6.8 and 7.4. The aggregation behavior of nanoemulsion at both the pH was found to be minimum and non-nephrotoxic. The stability of amphotericin B was obtained in terms of pH, optical density, globular size, polydispersity index and zeta potential value at different temperature for 90 days. The slowest drug degradation was observed in aqueous phase at pH 7.4 with shelf life 20.03-folds higher when stored at 4?°C (3.8 years) and 5-fold higher at 25?°C (0.951 years) than at 40?°C. The combined results suggested that nanoemulsion may hold an alternative for enhanced and sustained topical delivery system for amphotericin B.     

Loadability of power transformer under regional climate conditions: the case of Turkey

This paper presents an accurate methodology and examines the effects of long-term ambient temperature changes on the power transformer loadability and its service life loss considering regional climate characteristics. The daily ambient temperature variation is modeled on yearly basis for different climate regions according to historical records. For this purpose, four different regions are selected in Turkey. Thermal and service life loss models are tested under two loading conditions for selected climate projections. Models used in the study, are created in accordance with IEEE C57.91-95 and IEC 60076-7 standards. Calculations are made in high resolution as the basis of second distinct from related standards, for mineral oil-immersed power transformer parameters. In this way, the impact of regional climate conditions on power transformer loadability is determined more accurately. The results show that the power transformer loadability is a function of the regional climate conditions. In addition, the result of the analysis, some coefficients are recommended for power transformer loadability to complete a normal service life range (20.55 years) under selected regional climate conditions. This methodology is applicable to the different climate regions and power transformers outside scope of this study.     

Macroporous silicon: efficient antireflective layer on crystalline silicon

A macroporous silicon layer (ma-PS) electrochemically grown on crystalline silicon surface can be used as an efficient antireflective layer in optical devices as antireflection coating. In this work, we presented the ma-PS layers fabricated on crystalline silicon (c-Si) n-type and p ⁺-type, obtained by electrochemical etching. The morphology, porosity, thickness of ma-PS layer can be adjusted by controlling the electrochemical formation conditions. The optical behaviour of the antireflective coating over the solar spectrum is determined, resulting in very low values of the normalized reflectivity coefficient (below ~1%). The reflectivity measurements were evaluated at 45° in the different samples of the ma-PS/c-Si.     

Effect of high hydrostatic pressure and temperature on carrot peroxidase inactivation

The combined effects of pressure and temperature on the activity of carrot peroxidase (POD) were investigated in the pressure range 0.1–600 MPa and the temperature range 25–45 °C. At lower pressures (<396 MPa), carrot POD stability increased compared to unpressurized samples. Inactivation of 91% was obtained at 600 MPa and 45 °C. High hydrostatic pressure (HHP) combined with temperature treatment enhanced the inactivation of carrot POD. Regeneration of POD activity with the combined HHP and temperature treatments followed first order kinetics at 25, 35 and 40 °C. Regeneration was not observed at 506 MPa and 45 °C. HHP had no significant effect on the loss of vitamin C or on protein content. HHP combined with mild heat treatment was found to be better than the thermal treatment at high temperatures for inactivation of POD in carrot processing.     

Laminar Natural Convection of Bingham Fluids in Square Cross-Sectioned Cylindrical Annular Cavity with Differentially Heated Vertical Walls Subjected to Constant Heat Fluxes

Steady-state numerical simulations have been conducted to investigate natural convection of yield stress fluids obeying Bingham model in square cross-sectioned axisymmetric cylindrical annular enclosure with vertical walls subjected to constant heat fluxes for nominal Rayleigh number range of 10³ to 10⁶, nominal Prandtl number of 10 to 10³ for different values of internal cylinder radius. It is found that the mean Nusselt number on the inner periphery increases (decreases) with increasing nominal Rayleigh (Bingham) number due to strengthening (weakening) of thermal advection. However, the values of the mean Nusselt number on the inner periphery obtained for Bingham fluids are smaller than that obtained for Newtonian fluids for the same set of nominal Rayleigh and Prandtl numbers. The mean Nusselt number normalized by the corresponding value obtained for pure conductive transport increases with increasing internal radius before asymptotically approaching the mean Nusselt number for a square enclosure. This suggests that the ratio of the convective to the conductive transport strengthens with increasing cylinder radius in the cylindrical annular cavity. Detailed physical explanations have been provided for the effects of the aforementioned parameters on the mean Nusselt number on the inner periphery and correlations have been proposed for the mean Nusselt number on the inner periphery for both Newtonian and Bingham fluids.     

Synthesis,characterization and thermal properties of a novel star polymer consisting of poly(ε-caprolactone) arms emanating from an octa-functional porphyrazine core

Octaarmed star-shaped poly(ε-caprolactone) (OSPCL) was successfully synthesized via the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) with a magnesium porphyrazine as the multisite initiator and tin(II) 2-ethylhexanoate (Sn(Oct₂)) as the catalyst in bulk at 115 °C. The star polymer has a central Mg-porphyrazine surrounded by ε-CL arms. OSPCL was characterized by ¹H NMR, FTIR, GPC and UV–vis, and fluorescent spectroscopy. The effect of the molar ratio of the monomer to the initiator on molecular weight of the polymer was also investigated. The molecular weight of the polymer linearly increased with increasing molar ratio of the monomer to the initiator. The crystallization behavior of OSPCL was studied using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). OSPCL displayed an interrupted crystal morphology owing to its highly branched architecture, and consequently, the degree of crystallinity was lower in comparison with the linear analogue. Thermogravimetric analysis (TGA) clearly indicated that incorporation of porphyrazine core enhanced the thermal stability of the resulting polymers.     

The strategies and parameters of tabu search for job-shop scheduling

This paper presents a tabu search approach for the job-shop scheduling problem. Although the problem is NP-hard, satisfactory solutions have been obtained recently by tabu search. However, tabu search has a problem-specific and parametric structure. Therefore, in the paper, we focussed on the tabu search strategies and parameters such as initial solution, neighborhood structure, tabu list, aspiration criterion, elite solutions list, intensification, diversification and the number of iteration. In order to compare some neighborhood strategies and tabu list length methods, a computational study is done on the benchmark problems.