Buoyancy forces and activation energy on the MHD radiative flow over an exponentially stretching sheet with second‐order slip

The current study explores the effects of second‐order slip and activation energy (AE) on the magnetohydrodynamic and radiative fluid flow caused by a surface with exponential stretching. The binary chemical reaction with mixed convection is considered in this physical model to discover the heat transfer phenomenon. The governing system of equations leads to a set of nonlinear ordinary differential equations by using scaling analysis. The transformed system is calculated computationally by using the most powerful Shooting procedure with the support of MATLAB software. The characteristics of various flow parameters on the governing flow field are exhibited pictorially and deliberated. The results revealed that the coefficient of heat and mass transfer upsurge with growing values of the second‐order slip parameter and skin friction coefficient has a reverse effect on the first‐order slip parameter. The thermal measure of the fluid in the presence of suction and slip conditions is seen to be lesser than that with the nonslip and nonsuction conditions. The heat measure of the fluid augments with the rising buoyancy parameter. The influence of slips coupled with AE is significant in the fluid flow and heat transfer characteristics. The outputs of the current investigation are validated by comparing the Nusselt number with the available results and are found to closely agree as a limiting case.     

The release of fission-recoiled xenon from Zr-2.5 wt% Nb alloy

The release of fission-recoiled ¹³³Xe from Zr-2.5 wt% Nb alloy was measured in the temperature range 640–1080 K. In the range 640–880 K, where purely phase exists, a linear relationship between log D versus 1/T is observed and can be represented by the equation: D(640–880 K) = 6.24 × 10⁻⁹exp(−142.7 kJmol/RT)m²/s. The release has been attributed to the non-volume diffusion process.

In the temperature range 930–1080 K where both and β phases coexist, the linearity in the plots of log D versus 1/T is violated.

The present values of the release parameters have been compared with the corresponding values for the release of fission-recoiled ¹³³Xe from Zircaloy-2. Alloying elements seem to have very small effect on the release kinetics. The results have been presented and discussed.     

Itraconazole resistance in Aspergillus fumigatus

Invasive aspergillosis is an increasingly frequent opportunistic infection in immunocompromised patients. Only two agents, amphotericin B and itraconazole, are licensed for therapy. Itraconazole acts through inhibition of a P-450 enzyme undertaking sterol 14alpha demethylation. In vitro resistance in Aspergillus fumigatus to itraconazole correlated with in vivo outcome has not been previously described. For three isolates (AF72, AF90, and AF91) of A. fumigatus from two patients with invasive aspergillosis itraconazole MICs were elevated. A neutropenic murine model was used to establish the validity of the MICs. The isolates were typed by random amplification of polymorphic DNA. Analysis of sterols, inhibition of cell-free sterol biosynthesis from [14C] mevalonate, quantitation of P-450 content, and [3H]itraconazole concentration in mycelial pellets were used to determine the mechanisms of resistance. The MICs for the three resistant isolates were >16 microg/ml. In vitro resistance was confirmed in vivo for all three isolates. Molecular typing showed the isolates from the two patients to be genetically distinct. Compared to the susceptible isolate from patient 1, AF72 had a reduced ergosterol content, greater quantities of sterol intermediates, a similar susceptibility to itraconazole in cell-free ergosterol biosynthesis, and a reduced intracellular [3H]itraconazole concentration. In contrast, AF91 and AF92 had slightly higher ergosterol and lower intermediate sterol concentrations, fivefold increased resistance in cell-free systems to the effect of itraconazole on sterol 14alpha demethylation, and intracellular [3H] itraconazole concentrations found in susceptible isolates. Resistance to itraconazole in A. fumigatus is detectable in vitro and is present in wild-type isolates, and at least two mechanisms of resistance are responsible.     

Studies on chemically modified hen egg white and gelatin composites

Hen egg white (A) and gelatin (G) composites at different proportions were prepared and optimized by their stress–strain behavior. The optimized composite (AG) was graft copolymerised with methyl methacrylate (MMA). The AG and its graft copolymer AGMMA were characterized for their mechanical strength, water absorption capacity, Fourier transform infrared spectra, and circular dichroism (CD) spectroscopy. It was evident from the results that AGMMA possesses higher mechanical strength and lower water absorption capacity than does AG. The FTIR spectra of AG and AGMMA confirm the grafting phenomena of MMA onto AG, and the CD spectrum of AG shows two negative bands at around 207 and 222 nm and a positive band at around 191.76 nm, which confirms the α‐helix in the composite. The α‐helical structure in AG was broken and converted into unordered random coil in AGMMA because of the reaction conditions while grafting MMA onto AG, which was confirmed by the increase in mechanical strength of AGMMA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 318–322, 2006     

Optimum culture medium composition for rhamnolipid production by pseudomonas aeruginosa AT10 using a novel multi‐objective optimization method

BACKGROUND: Rhamnolipid is a biosurfactant that finds wide applications in pharmaceuticals and beauty products. Pseudomonas aeruginosa is a producer of rhamnolipids, and the process can be implemented under laboratory‐scale conditions. Rhamnolipid concentration depends on medium composition namely, carbon source concentration, nitrogen source concentration, phosphate content and iron content. In this work, existing data⁷ were used to develop an artificial neural network‐based response surface model (ANN RSM) for rhamnolipid production by pseudomonas aeruginosa AT10. This ANN RSM model is integrated with non‐dominated sorting differential evolution (DE) to identify the optimum medium composition for this process. RESULTS: Different strategies for optimization of culture medium composition for this process were evaluated, and the best determined to be an ANN model combined with DE involving a combination of Naïve and Slow and ε‐constrained techniques. The optimal culture medium is determined to have carbon source concentration of 49.86 g dm^?3, nitrogen source concentration of 4.99 g dm^?3, phosphate content of 1.42 g dm^?3, and iron content of 17.12 g dm^?3. The maximum rhamnolipid activity was found to be 18.07 g dm^?3, which compares favorably with that previously reported (18.66 g dm^?3), and is in fact closer to the experimentally determined value of 16.50 g dm^?3. CONCLUSION: This method has distinct advantages over methods using statistical regression models, and can be used for optimization of other multi‐objective biosurfactant production processes. © 2012 Society of Chemical Industry     

Sol–gel synthesis and characterization of Li2O–As2O5–SiO2 glassy system

The ternary 10% Li₂O + 90% (xAs₂O₅ + (1 − x) SiO₂) (x = 0.025, 0.05, 0.075 and 0.1) (LAS) glassy system with different compositions were prepared using sol–gel technique. All the prepared samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and differential scanning calorimetry techniques. The observed peak-free XRD patterns confirm the amorphous phase of the prepared LAS compounds. Structural coordination of LAS glassy samples was confirmed by Fourier transform infrared spectroscopy. Thermal behavior of the glassy samples was characterized by differential scanning calorimetry. Bulk conductivity of all the LAS glassy samples was calculated by analyzing the impedance data measured at different temperatures. Activation energy (E_a) is evaluated from the log σT vs. 1000/T plot and it is found to be 0.837 eV.     

Yield prediction and waterlogging assessment for tea plantation land using satellite image‐based techniques

Motivated by the operational use of remote sensing in various agricultural crop studies, this study evaluates the application and utility of remote sensing‐based techniques in yield prediction and waterlogging assessment of tea plantation land in the Assam State of India. The potential of widely used vegetation indices like NDVI and SR (simple ratio) and the recently proposed TVI has been evaluated for the prediction of green leaf tea yield and made tea yield based on image‐derived leaf area index (LAI), along with weather parameters. It was observed that the yield model based on the TVI showed the highest correlation (R² = 0.83) with green leaf tea yield. The NDVI‐ and SR‐based models suffered non‐responsiveness when the yield approached maximum. The NDVI and SR showed saturation when the LAI exceeded a magnitude of 4. However, the TVI responded well, even when the LAI exceeded 5, and thus has potential use in the estimation of the LAI of dense vegetation such as some crops and forest where it generally exceeds the threshold value of 4.

An attempt was made for the innovative application of TCT and NDWI in the mapping of waterlogging in tea plantation land. The NDWI in conjunction with TCT offered fairly good accuracy (87%) in the delineation of tea areas prone to waterlogging. This observation indicates the potential of NDWI and TCT in mapping waterlogged areas where the soil has considerable vegetation cover.     

Synthesis and Characterisation of Polyamides and Polyimides from Amino/Methylene bis[Benzenamine] Styryl Pyridines

Polyamides and polyimides containing diamines, with potential non-linear optical characteristics, were prepared using (E)-4,4′-[[[2-(4-pyridinyl)ethenyl]phenyl]amino]bis[benzenamine] and (E)-4-4′-[[[2-(4-pyridinyl)ethenyl]2-methyl phenyl]amino]bis[benzenamine] condensed with pyromellitic dianhydride to obtain poly(amic acid)s. The poly(amic acid)s were soluble in polar aprotic solvents, such as dimethylformamide, dimethylsulphoxide and dimethylacetamide, and could be cast into transparent, tough, flexible films. Amorphous thermally stable polyimides were formed by cyclodehydration. Similarly, (E)-4,4′-[[[2-(4-pyridinyl)ethenyl]phenyl]methylene]bis[benzenamine] and (E)-4,4′-[[[2-(4-pyridinyl)ethenyl]phenyl]methylene]bis[N-ethylbenzenamine] were condensed with 3-methyladipoyl chloride to obtain other new polyamides. Characterisation using infra-red and nuclear magnetic resonance spectroscopy, X-ray diffraction and thermogravimetric analysis are reported. © 1997 SCI.     

Investigation of cytochrome P450 mediated benzo(a)pyrene hydroxylation in Aspergillus fumigatus

Microsomal fractions of Aspergillus fumigatus exhibited a reduced carbon monoxide difference spectrum with a maximum at 448 nm and a substrate-induced Type I spectrum on addition of benzo(a)pyrene. Metabolism of benzo(a)pyrene, as measured using the aryl hydrocarbon hydroxylase assay, was found to be P450-dependent and activity was observed to have a K_m of 82 μM and V_max of 33·3 pmol min⁻¹ mg⁻¹ protein. P450 productivity was investigated during growth from spore inocula and observed to be constant until the stationary phase, where the specific content declined to undetectable levels. The specific content of P450 was found to increase in higher concentrations of glucose.