Effect of ultrasound on different quality parameters of apple juice

Fresh apple juice treated with ultrasound (for 0, 30, 60 and 90 min, at 20 °C, 25 kHz frequency) was evaluated for different physico-chemical, Hunter color values, cloud value, antioxidant capacity, scavenging activity on 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical, ascorbic acid, total phenolics, flavonoids, flavonols and microbial characteristics. No significant effect of sonication was observed on pH, total soluble solids (°Brix) and titratable acidity of apple juice. Sonication significantly improved ascorbic acid, cloud value, phenolic compounds, antioxidant capacity, DPPH free radical scavenging activity and differences in Hunter color values. Moreover, significant reduction in microbial population was observed. Findings of the present study suggested that sonication treatment could improve the quality of apple juice. It may successfully be employed for the processing of apple juice with improved quality and safety from consumer’s health point of view.     

Multi-stage IT project evaluation: The flexibility value obtained by implementing and resolving Berk, Green and Naik (2004) model

In this paper, we evaluate a multi-stage information technology investment project, by implementing and resolving Berk, Green and Naik’s (2004) model, which takes into account specific features of IT projects and considers the real option to suspend investment at each stage. We present a particular case of the model where the project value is the solution of an optimal control problem with a single state variable. In this case, the model is more intuitive and tractable. The case study confirms the practical potential of the model and highlights the importance of the real-option approach compared to classical discounted cash flow techniques in the valuation of IT projects.     

Kinetics of the acyl migration in some adducts of acyl-1, 4-benzoquinones: Part I

The rates of migration of acetyl, propionyl, isobutyryl, and benzoyl substituent in Diels-Alder adducts of acyl-1, 4-benzoquinones, (enediones), (I), to form the corresponding 2-acyl hydroquinones, (II), in 50% (v/v) ethanolic pyridine have been studied in detail. Rate dependence on pyridine concentration has been established and maximum rate was found at pyridine a volume percent of 25 in an ethanolic reaction mixture. The study indicated first-order dependence on reactants and fractional dependence on pyridine concentration. The effect of substituents of the acyl group on the rate showed that electronic factors play an important role on the stability of the transition state. A plausible mechanism, which is consistent with the results has been postulated and suitable rate law in consonance with the postulated mechanism have been derived.     

Transition to chaos via the quasi-periodicity and characterization of attractors in confined Bénard-Marangoni convection

A study of dynamic regimes in Bénard-Marangoni convection was carried out for various Prandtl and Marangoni numbers in small aspect ratio geometries (Γ = 2.2 and 2.8). Experiments in a small hexagonal vessel, for a large range of the Marangoni number (from 148 to 3636), were carried out. Fourier spectra and an auto-correlation function were used to recognize the various dynamic regimes. For given values of the Prandtl number (Pr = 440) and aspect ratio (Γ = 2.2), mono-periodic, bi-periodic and chaotic states were successively observed as the Marangoni number was increased. The correlation dimensions of strange attractors corresponding to the chaotic regimes were calculated. The dimensions were found to be larger than those obtained by other authors for Rayleigh-Bénard convection in aspect ratio geometries of the same order. The transition from temporal chaos to spatio-temporal chaos was also observed. For Γ = 2.2, when larger values of the Marangoni number were imposed (Ma = 1581 for Pr = 160 and Ma = 740 for Pr = 440), spatial modes were involved through the convective pattern dynamics.     

Comparisons of RZ-OOK and RZ-DPSK in dense OTDM-WDM systems using Q factor models

In view of the differential phase Q (DP-Q) and the traditional Q factor, we compared, using numerical simulations, the performances of the RZ-OOK and RZ-DPSK in dense OTDM-WDM systems. When signal pulse widths and optical filter bandwidths are optimized, there is no upper limit to the WDM channel bit rate (BR) in the purely linear back-to-back configuration. Here, RZ-DPSK performed increasingly better than RZ-OOK in a higher spectral density with Q gain increasing from 3 to 5 dB. In the nonlinear point-to-point configuration, a higher BR leads to increased performance penalties for both the RZ-DPSK and RZ-OOK, while the RZ-DPSK still outperforms RZ-OOK by up to 4 dB. The results obtained correlate with conventional results, indicating the potential of the DP-Q as a performance evaluation tool in numerical simulations.     

In vitro anti-acne activity of phytoactives from the stem bark of Artocarpus hirsutus Lam. and characterisation of pyranocycloartobiloxanthone A as a mixture of two anomers

This study is aimed to isolate the phytoactives from the stem bark of Artocarpus hirsutus and evaluate their in vitro anti-acne activity. The ethanolic stem bark extract of A. hirsutus provided two major phytoactive constituents: (i) pyranocycloartobiloxanthone A, (1) and (ii) Artonine E, (2) whose structures were determined by NMR and MS spectroscopic analysis. The present study is the first to report compound 1 as a mixture of two anomers (α and β), approximately 70:30 ratio. Both compounds 1 and 2 were isolated for the first time from this plant. In vitro anti-acne activity of compounds 1 and 2 were evaluated by agar well diffusion method and the minimum inhibition was determined by broth micro dilution method. The result of anti-microbial activity (MIC = 2.0 μg/mL each) is comparable to antibiotic, Clindamycin (MIC = 0.03 μg/mL) and clearly demonstrate their potential as anti-acne agents.     

Elution behavior of unsaponifiable lipids with various capillary electrochromatographic stationary phases

Capillary electrochromatographic (CEC) separations of unsaponifiable lipids, tocopherols (T), tocotrienols (T3), and plant sterols were studied under various conditions. Investigated stationary phases include pentafluorophenylsilica (PFPS), triacontylsilica (TCS), and octadecylsilica (ODS) phases. A baseline separation of four sterols (ergosterol, lanosterol, sitosterol and stigmasterol) on ODS was achieved and their elution order was found to be dictated by side-chain structures. CEC of the tocol-derived compounds on PFPS in aqueous methanol yielded the most satisfactory results with complete resolution of all components eluting in the order deltaT3>beta3>gammaT3>epsilonP>alphaT3>deltaT>zeta2T>betaT>gammaT>alphaT, while a reversal in elution of the epsilonT-alphaT3 pair was observed in aqueous acetonitrile. CEC with a TCS phase in non-aqueous methanol led to a different elution pattern deltaT3>gammaT3>betaT3>alphaT3epsilonT>deltaT>(zeta2+gamma)T>betaT>alphaT, despite favorable resolution of the (gamma-zeta2)T pair along with the observation of inseparable(beta-gamma)T and (beta-gamma)T3 pairs in non-aqueous dimethylformamide. Non-aqueous acetonitrile mobile phases provided unique selectivity for the (gamma-zeta2)T pair and isomer separations on TCS. Variations in separation and retention factors of relevant antioxidant species with CEC variables were evaluated. Examples of CEC quantification of unsaponifiable fractions of rice bran oils and soybean oils are presented.     

Synthesis and Characterization of Porous Silica-Alumina Xerogels

Porous silica-alumina xerogels are synthesized through two methods, which differ by the aluminium precursor: aluminium tri-secbutoxide and aluminium nitrate nonahydrate. The silicium precursor is tetraethylorthosilicate. The porous texture is studied by nitrogen adsorption-desorption isotherms. It is found that the porous texture mainly depends on one parameter for each preparation method: hydrolysis catalyst in one case and aluminium content in the other case.