Cholesterol in eggs from different species of poultry determined by capillary GLC

This study compared two methods of egg cholesterol extraction and determination by gas liquid chromatography (GLC), validated by comparison with standard reference material (SRM 1845). The two extraction procedures were of comparable accuracy with dried whole egg samples of 0·25–0·5 g, but the direct saponification method was rapid, reduced occupational hazard, and quantitative precision was within 2% coefficient of variation. The validated procedure was used to determine cholesterol in eggs of several domestic avian species. Eggs produced by commercial types of chicken (White Leghorn) had the lowest cholesterol (11·5–11·8 mg/g yolk) compared to 13·0, 14·6, 15·2, 15·6, 16·5, 16·8 and 18·1 mg/g for Rhode Island Red chicken, guinea fowl, New Hampshire chicken, duck, pea fowl, domestic turkey and wild turkey eggs, respectively. Yolk cholesterol concentration of commercial White Leghorn chicken eggs was not influenced by age. However, eggs from older birds contained about 23% more cholesterol on a per egg basis (220 versus 179 mg) because of the larger yolk.     

Development of Nitrendipine Controlled Release Formulations Based on SLN and NLC for Topical Delivery: In Vitro and Ex Vivo Characterization

The aim of the investigation is to develop solid lipid nanoparticles (SLN) and nano-structured lipid carrier (NLC) as carriers for topical delivery of nitrendipine (NDP). NDP-loaded SLN and NLC were prepared by hot homogenization technique followed by sonication, and they were characterized for particle size, zeta potential, entrapment efficiency, stability, and in vitro release profiles. Also the percutaneous permeation of NDPSLN A, NDPSLN B, and NDPNLC were investigated in abdominal rat skin using modified Franz diffusion cells. The steady state flux, permeation coefficient, and lag time of NDP were estimated over 24 h and compared with that of control (NDP solution). The particle size was analyzed by photon correlation spectroscopy (PCS) using Malvern zeta sizer, which shows that the NDPSLN A, NDPSLN B, and NDPNLC were in the range of 124–300 nm during 90 days of storage at room temperature. For all the tested formulations (NDPSLN A, NDPSLN B, and NDPNLC), the entrapment efficiency was higher than 75% after 90 days of storage. The cumulative percentage of drug release at 24 h was found to be 26.21, 30.81, and 37.52 for NDPSLN A, NDPSLN B, and NDPNLC, respectively. The results obtained from in vitro release profiles also indicated the use of these lipid nanoparticles as modified release formulations for lipophilic drug over a period of 24 h. The data obtained from in vitro release from NDPSLN A, NDPSLN B, and NDPNLC were fitted to various kinetic models. High correlation was obtained in Higuchi and Weibull model. The release pattern of drug is analyzed and found to follow Weibull and Higuchi equations. The permeation profiles were obtained for all formulations: NDPSLN A, NDPSLN B, and NDPNLC. Of all the three formulations, NDPNLC provided the greatest enhancement for NDP flux (21.485 ± 2.82 μg/h/cm²), which was fourfold over control (4.881 ± 0.96 μg/h/cm²). The flux obtained with NDPSLN B (16.983 ± 2.91 μg/h/cm²) and NDPNLC (21.485 ± 2.82 μg/h/cm²) meets the required flux (16.85 μg/h/cm²).     

Substrate temperature dependent physical properties of sprayed Zn0.76Mg0.24O films

The composition, microstructural and opto-electronic properties of Zn_1?x Mg _x O thin films grown by spray pyrolysis have been studied. The films were prepared on glass substrates at different substrate temperatures in the range, 200–350 °C for a fixed magnesium composition of x = 0.24. The films showed the predominant (002) reflection corresponding to the hexagonal wurtzite structure of ZnO. The preferred orientation doesn’t change with the deposition temperature. The films prepared at 300 °C showed good crystallinity with an average surface roughness of 6.2 nm. The optical studies revealed that the optical transmittance increased slightly with the increase of substrate temperature of the films. The variation of energy band gap, photoluminescence and electrical resistivity of the grown layers was also studied.     

Speaker verification using committee neural networks

Security is a major problem in web based access or remote access to data bases. In the present study, the technique of committee neural networks was developed for speech based speaker verification. Speech data from the designated speaker and several imposters were obtained. Several parameters were extracted in the time and frequency domains, and fed to neural networks. Several neural networks were trained and the five best performing networks were recruited into the committee. The committee decision was based on majority voting of the member networks. The committee opinion was evaluated with further testing data. The committee correctly identified the designated speaker in (50 out of 50) 100% of the cases and rejected imposters in (150 out of 150) 100% of the cases. The committee decision was not unanimous in majority of the cases tested.     

Selective preconcentration and determination of chromium(VI) using a flat sheet polymer inclusion sorbent: potential application for Cr(VI) determination in real samples

A method for sorption preconcentration of Cr(VI) from aqueous samples was developed using a polymer inclusion sorbent (PIS). The PIS used in this method was prepared by physical inclusion of Aliquat-336 in the matrix formed by cellulose triacetate and 2-nitrophenyl octyl ether. This sorbent was found to be stable, cost-effective, efficient for preconcentration of Cr(VI) present in the aqueous samples, and amenable to direct quantitative analysis of Cr(VI) held in it by neutron activation analysis and spectrophotometry. The quantifying of Cr(VI) in PIS by spectrophotometry was carried out by developing color directly on the PIS after reacting it with 1,5-diphenylcarbazide. The distinct color developed on the PIS even at very low concentrations of Cr(VI) suggests its possible use for field determination of Cr(VI). The composition of PIS was optimized to obtain maximum uptake of Cr(VI) without sacrificing uniformity in terms of thickness and distribution of ion-exchange sites, stability, and time required for quantitative sorption of Cr(VI) from aqueous samples. The Cr(VI) species held in the PIS, mainly HCrO4- and CrO4(2-), were found to vary as a function of pH of the aqueous samples from which Cr(VI) was preconcentrated. A close agreement was found in the abundances of Cr(VI) species held in the PIS with those reported in the literature for aqueous solutions at different pH. The variation of Cr(VI) species as a function of pH was found to have a significant impact on the tolerance to anions on the uptake of Cr(VI) in the PIS. The high selectivity of PIS toward Cr(VI) from aqueous solution at pH = 2 was explained on the basis of hydration of anions. The uptake of Cr(VI) was found to be fairly constant (88 +/- 3%) up to nearly complete exchange of counterions present in the PIS. The method developed in the present work was successfully used for the preconcentration of Cr(VI) from tap water and seawater samples containing low levels of Cr(VI).     

Solid–liquid extraction of terbium from phosphoric acid solutions using solvent‐impregnated resin containing TOPS 99

BACKGROUND: In this work, the solid‐liquid extraction of terbium from phosphoric acid solutions using solvent‐impregnated resin containing TOPS 99, an equivalent of di‐2‐ethylhexyl phosphoric acid, has been investigated. The parameters studied include equilibration time, acid concentration, amount of resin, metal concentration, kinetics, temperature, loading, elution, regeneration and recycling. RESULTS: FT‐IR results confirm the physical interaction of the extractant with the resin. The extraction of terbium with TOPS 99 impregnated Amberlite XAD 4 resin was acid dependent and transfer of metal follows a cation exchange mechanism. The loading capacity of TOPS 99‐impregnated resin for terbium was calculated to be 23.8 mg g^?1 resin. Controlling mechanism of the adsorption was found to be a chemical reaction following pseudo‐second‐order kinetics. The endothermic nature of extraction was confirmed by temperature studies. Among the various eluants studied, H₂SO₄ was the best. Regeneration and recycling of the resin indicated the resin can be used for continuous cycles. CONCLUSIONS: Terbium was successfully extracted from phosphoric acid using TOPS 99 extractant impregnated into Amberlite XAD4 with a maximum loading of 23.8 mg g^?1 resin and fully recovered with 1 mol L^?1sulfuric acid. The resin was subjected to seven cycles of extraction and elution without any loss of performance. Further studies showed that terbium could be separated from lutetium. Copyright © 2010 Society of Chemical Industry     

A Microplate Format Assay for Real‐Time Screening for New Aldolases that Accept Aryl‐Substituted Acceptor Substrates

Aldolases are potentially important biocatalysts for asymmetric synthesis of polyhydroxylated compounds. Fructose 6‐phosphate aldolase (FSA) is of particular interest by virtue of its unusually relaxed dependency on phosphorylated substrates. FSA has been reported to be a promising catalyst of aldol addition involving aryl‐substituted acceptors such as phenylacetaldehyde that can react with donor ketones such as hydroxyacetone. Improvement of the low intrinsic activity with bulky acceptor substrates of this type is of great interest but has been hampered by the lack of powerful screening protocols applicable in directed evolution strategies. Here we present a new screen allowing for direct spectrophotometric recording of retro‐aldol cleavage. The assay utilizes an aldehyde reductase produced in vitro by directed evolution; it reduces the aldehyde product formed after cleavage of the aldol by FSA. The assay is suitable both for steady‐state enzyme kinetics and for real‐time activity screening in a 96‐well format.     

Effects of hydrosilyl monomers on the performance of polysiloxane encapsulant/phosphor blend based hybrid white‐light‐emitting diodes

Polysiloxane‐based encapsulants were prepared by a hydrosilylation reaction of methacryl polyhedral oligomeric silsesquioxane and different hydrosilyl monomers. With the wavelength conversion method, white‐light‐emitting diodes (WLEDs) were produced by the application of a thermally cured polysiloxane encapsulant/phosphor composite as a wavelength converter on blue‐light‐emitting InGaN diodes. The color rendering index, the Commission Internationale de l'Éclairage coordinates, correlated the color temperature, and the luminous efficacy of the WLEDs with different encapsulants were evaluated. The effects of the chemical structures of hydrosilyl monomers on the optical, mechanical, and thermal resistance properties of the encapsulants, together with the performance of the WLEDs, were investigated. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44524.     

Chitosan–poly(aminopropyl/phenylsilsesquioxane) hybrid nanocomposite membranes for antibacterial and drug delivery applications

We fabricated hybrid (CSSQ) membranes from chitosan and poly(aminopropyl/phenylsilsesquioxane) (PAPSQ) blends via a sol–gel reaction and solution casting followed by crosslinking with glutaraldehyde. The CSSQ membranes were then used for loading of 5‐fluorouracil (5‐FU) as an anticancer drug as well as templates for the production of silver nanoparticles (AgNPs). The physicochemical properties of the CSSQ membranes were examined using UV‐visible spectroscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis and scanning electron microscopy (SEM). SEM results showed the controllable formation of AgNPs around PAPSQ. CSSQ–Ag nanocomposite membranes exhibited good antibacterial activity towards both Escherichia coli and Bacillus subtilis, while the CSSQ membranes worked as good carriers for controlled release of 5‐FU as model drug. The results suggest that both CSSQ and CSSQ–Ag nanocomposite membranes can be potentially applied for biomedical applications such as controlled release carriers as well as antibacterial wound dressing materials. © 2014 Society of Chemical Industry