Numerical assessment of mixing performances in cross-T microchannel with curved ribs

Microsystem Technologies - The present study considers a measure for enhancing mixing capability in micromixers. It incorporates a new design of obstacle, in the form of thin curved ribs, inside...     

Color tunable nanocrystalline SrGd2Al2O7:Tb3+ phosphor for solid state lighting

Color tunable Tb³⁺ doped SrGd₂Al₂O₇ nanophosphor is synthesized employing a facile and economic urea assisted solution combustion approach. XRD studies confirm the crystallization of single phased SrGd_2(1-x)Tb_2xAl₂O₇ nanophosphor in tetragonal lattice with I4/mmm (139) space group. Rietveld refinement is performed over SrGd_1.9Tb_0.1Al₂O₇ sample to execute qualitative as well as quantitative phase analysis. TEM analysis confirms the more or less spherical shaped phosphors in nano domain with average particle size ranging 45–80?nm. Photoluminescent investigation reveals that this nanophosphor can be successfully excited by ultraviolet light yielding significant luminescent properties arising due to radiative transitions from ⁵D_3,4 levels to ⁷F_j levels. Dipole-dipole interactions are solely responsible for the energy transfer causing concentration quenching. Concentration controlled luminescent tendency can be employed to induce chromaticity from blue to green region. Findings of the study proclaim the application of this nanophosphor as one of the green component of tricolor based ultraviolet excited white LEDs.     

Design,optimization and evaluation of poly-ɛ-caprolactone (PCL) based polymeric nanoparticles for oral delivery of lopinavir

Lopinavir (LPV)-loaded poly-ε-caprolactone (PCL) nanoparticles (NPs) were prepared by emulsion solvent evaporation technique. Effects of various critical factors in preparation of loaded NPs were investigated. Box–Behnken design (BBD) was employed to optimize particle size and entrapment efficiency (EE) of loaded NPs. Optimized LPV NPs exhibited nanometeric size (195.3?nm) with high EE (93.9%). In vitro drug release study showed bi-phasic sustained release behavior of LPV from NPs. Pharmacokinetic study results in male Wistar rats indicated an increase in oral bioavailability of LPV by 4-folds after incorporation into PCL NPs. From tissue distribution studies, significant accumulation of loaded NPs in tissues like liver and spleen indicated possible involvement of lymphatic route in absorption of NPs. Mechanistic studies using rat everted gut sac model revealed endocytosis as a principal mechanism of NPs uptake. In vitro rat microsomal metabolism studies demonstrated noticeable advantage of LPV NPs by affording metabolic protection to LPV. These studies indicate usefulness of PCL NPs in enhancing oral bioavailability and improving pharmacokinetic profile of LPV.     

Material selection for thin-film solar cells using multiple attribute decision making approach

This paper presents a material selection approach for selecting absorbent layer material for thin-film solar cells (TFSCs) using multiple attribute decision making (MADM) approach. In this paper, different possible materials for absorbent layer and their properties like band gap, absorption coefficient, diffusion length, thermodynamic compatibility and recombination velocity is taken into consideration and MADM approach is applied to select the best material for thin-film solar cells. It is observed that Copper Indium Gallium Diselinide (CIGS) is the best material for the absorbent layer in thin-film solar cells out of all possible candidates. It was observed that the proposed result is in accordance with the experimental findings thus justifying the validity of the proposed study.     

Unsteady wake dynamics and heat transfer in forced and mixed convection past a circular cylinder in cross flow for high Prandtl numbers

This paper investigates the combined effect of Prandtl number and Richardson number on the wake dynamics and heat transfer past a circular cylinder in crossflow using a SUPG based finite element method. The computations are carried out for 80 < Re < 180, 0.7 < Pr < 100 and $0?\mathrm{Ri}?2$. The results have been presented for both forced and mixed convection flows. In the case of forced convection, crowding of temperature contours with reduced spatial spread is observed for increasing Prandtl numbers. The local and average Nusselt numbers are found to increase with increasing Reynolds number and Prandtl number. The average Nusselt number and Colburn factor are found to vary as Re^0.548 Pr ^0.373 and Re^?0.452, respectively. The extrapolated results of the average Nusselt number for low and high Reynolds numbers are found to match quite well with the available results in literature. Effect of Prandtl number shows various interesting phenomena for the mixed convective flows. Increasing the Prandtl numbers resulted in decreasing deflection and strength in the wake structures. The effect of baroclinic vorticity production during vortex shedding has been demonstrated at the vicinity of the cylinder and near wake. The Strouhal number is found to decrease with increasing Prandtl number, in the case of buoyancy induced flow. The effect of increasing Prandtl number is manifested as the stabilizing effect in the flow. This is, perhaps, the first time that such behavior for the Prandtl number is being reported. Additionally it is observed that the average Nusselt number decreases with increasing Richardson number.     

Nanoencapsulation and immobilization of cinnamaldehyde for developing antimicrobial food packaging material

Use of antimicrobial coatings on food packaging is one of the important technologies of active packaging for improving food safety. There is growing demand for natural antimicrobials because of fear of adverse health effects of synthetic preservatives. The objectives of this study were to compare antibacterial properties of free and nanoencapsulated cinnamaldehyde in solution; polylactic acid (PLA) surfaces cast with cinnamaldehyde; and glass and PLA surfaces coated with cinnamaldehyde nano-liposomes. Cinnamaldehyde was nano-encapsulated by lipid bilayers of polydiacetylene – N-hydroxysuccinimide (PDA–NHS) nano liposomes and immobilized on glass slides and PLA films. Glass surfaces immobilized with nano-encapsulated cinnamaldehyde showed significant antibacterial activity against Escherichia coli W1485 and Bacillus cereus ATCC 14579, with reductions of 2.56 log₁₀ CFU/ml and 1.59 log₁₀ CFU/ml respectively in 48 h. PLA films cast with cinnamaldehyde also showed significant antibacterial activities against E. coli W1485 (2.01 log₁₀ CFU/ml reduction) and B. cereus (4.81 log₁₀ CFU/ml reduction). However, when the liposomal encapsulated cinnamaldehyde was immobilized on PLA films, it did not show any antibacterial activity. Glass surfaces coated with nano-encapsulated cinnamaldehyde may be used as an active packaging material in preserving liquid foods; however, further study is required to improve antimicrobial activities of PLA surfaces.     

Manganese dioxide — a review of a battery chemical Part II. Solid state and electrochemical properties of manganese dioxides

A literature survey indicated that the properties such as electrical conductivity, magnetic susceptibility, thermal decomposition temperature and water content influence the activity of manganese dioxides.Infrared spectroscopy is considered as a convenient analytical tool with which to characterize the various crystal phases of the dioxides. Increasing attention has also been given to predicting the potentials of the system (MnO₂)_1?r. MnOOH_r during electrochemical reduction with a view to understanding the observed discharge characteristics.Further, attempts are being made to correlate the activity of the dioxides with their structural features.     

Association of insulin resistance to electrocardiographic changes in non obese Asian Indian subjects with hypertension

Although it is well documented that child maltreatment exerts a deleterious impact on child adaptation, much less is known about the precise etiological pathways that eventuate in child abuse and neglect. This paper reports on a multimethod ecological study of the relationship between neighborhood structural factors and child maltreatment reports in African American and European American census tracts. The study had two major components. First, in an aggregate analysis, the effects of four measures of community structure (impoverishment, child care burden, instability, and geographic isolation) on child maltreatment report rates were examined separately for predominantly African American (n = 94) and predominantly European American (n = 189) census tracts. Impoverishment in particular had a significantly weaker effect on maltreatment rates in African American than in European American neighborhoods. Second, focused ethnographies were conducted in four selected census tracts with child maltreatment report rates in the highest and lowest quartiles. Ethnographic data point to the importance of the social fabric in accounting for differences in child maltreatment report rates by predominant neighborhood ethnicity.