3,846 research outputs found

    Frequency-selective near-field enhancement of radiative heat transfer via photonic-crystal slabs: a general computational approach for arbitrary geometries and materials

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    We demonstrate the possibility of achieving enhanced frequency-selective near-field radiative heat transfer between patterned (photonic crystal) slabs at designable frequencies and separations, exploiting a general numerical approach for computing heat transfer in arbitrary geometries and materials based on the finite-difference time-domain method. Our simulations reveal a tradeoff between selectivity and near-field enhancement as the slab--slab separation decreases, with the patterned heat transfer eventually reducing to the unpatterned result multiplied by a fill factor (described by a standard proximity approximation). We also find that heat transfer can be further enhanced at selective frequencies when the slabs are brought into a glide-symmetric configuration, a consequence of the degeneracies associated with the non-symmorphic symmetry group

    The influence of Al3+ion on porcine pepsin activity in vitro

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    The in vitro effect of Al3+ ions in the concentration range 1.710-6M-8.710-3M on pepsin activity at pH 2, via kinetic parameters and its electrophoretic mobility was evaluated. Kinetic study demonstrated the existence of an activation effect of Al3+ at pH 2 on pepsin molecule. Kinetic analysis with respect to concentrations of haemoglobin showed that Al3+ ions increase the maximal velocity (Vmax) and kcat values rather than apparent affinity for substrate (KS) implying the non-competitive nature of activation which indicated that aluminium was a non-essential activator of partial non-competitive type. The values of the equilibrium constants KS and KmA for dissociation of corresponding complexes were evaluated as 0.9040.083mM and 8.560.51M, respectively. Dissociation constant KA, of activator from enzyme-activator complex calculated via kinetic and direct measurement of Al3+ binding data, as well as activation constant A50, the activator concentration that gives a rate equal to half at a saturating concentration of activator, were found to be 8.820.90M, 8.390.76M, and 8.050.48M respectively. Native PAGE electrophoresis shows the decrease in electrophoretic mobility of pepsin and confirms modification of the electric charge and conformational changes of pepsin caused by bound Al3+ on the pepsin molecule. Al3+ induced conformational changes of pepsin were verified by UV-VIS and IR spectra. Moreover, the absence of conformational changes in the haemoglobin molecule in the presence of Al3+ ions confirms that the obtained activation is a consequence of conformational changes caused only in the pepsin molecule

    Genomics-Based Insights Into the Biosynthesis and Unusually High Accumulation of Free Fatty Acids by Streptomyces sp NP10

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    Schneider O, Ilic-Tomic T, Rückert C, et al. Genomics-Based Insights Into the Biosynthesis and Unusually High Accumulation of Free Fatty Acids by Streptomyces sp NP10. FRONTIERS IN MICROBIOLOGY. 2018;9: 10.Streptomyces sp. NP10 was previously shown to synthesize large amounts of free fatty acids (FFAs). In this work, we report the first insights into the biosynthesis of these fatty acids (FAs) gained after genome sequencing and identification of the genes involved. Analysis of the Streptomyces sp. NP10 draft genome revealed that it is closely related to several strains of Streptomyces griseus. Comparative analyses of secondary metabolite biosynthetic gene clusters, as well as those presumably involved in FA biosynthesis, allowed identification of an unusual cluster C12-2, which could be identified in only one other S. griseus-related streptomycete. To prove the involvement of identified cluster in FFA biosynthesis, one of its three ketosynthase genes was insertionally inactivated to generate mutant strain mNP10. Accumulation of FFAs in mNP10 was almost completely abolished, reaching less than 0.01% compared to the wild-type strain. Cloning and transfer of the C12-2 cluster to the mNP10 mutant partially restored FFA production, albeit to a low level. The discovery of this rare FFA biosynthesis cluster opens possibilities for detailed characterization of the roles of individual genes and their products in the biosynthesis of FFAs in NP10

    Monte Carlo Analysis of the Influence of Different Packaging on MOSFET Energy Response to X-rays and Gamma Radiation

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    Radiation sensing MOSFETs have found numerous applications as detectors or device components in radiation fields used in nuclear industry, medical applications and space research. Monte Carlo simulations of MOSFET energy response to X-ray and gamma radiation for different packaging were performed. The photon transport Monte Carlo software FOTELP-2K10 has been adapted to obtain the energy deposited in MOSFET structure with microscopic dimensions. In this work the ratio between values of total energy deposited in the sensitive volume (thick SiO2 layer) for cases of MOSFET structure with and without package lid is presented. For this purpose is defined the shielding energy dependence factor (SDEF), and gave its value for kovar and Ti-24Al-11Nb and Ti-13Nb-13Zr alloys as lid materials

    Anthropometric study of the facial index in the population of Central Serbia

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    The aim of this study was to determine the craniofacial parameters in the population of the central part of Serbia. The research was conducted on 700 persons (360 males and 340 females), aged 18-65 years, selected randomly. The measured parameters were morphological facial height and breadth. The standard spreading caliper with scale was used for the measurement of facial parameters. There were significant differences in the facial parameters of male compared to female subjects in all observed parameters. The mean value of the morphological facial height in the study population was 116.8 mm ± 7.28, maximum facial breadth 124.12 mm ± 8.44, while the mean value of the total facial index was 93.68 ± 6.86. The total facial index was calculated according to the formula and the obtained results were analyzed statistically using the t-test. The dominant phenotype in the studied population was leptoprosopic. The data obtained in our study may be useful in anthropological research, forensics, genetic research, as well as in medical clinical practice

    Routes to sustainability in public food procurement: An investigation of different models in primary school catering

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    Increasingly, policymakers are setting ambitious goals for sustainability in public procurement, integrated across different pillars. Such ambitions are apparent in public catering services, where procurement models have been shifting towards greater localisation of supply chains and purchasing of more organically grown food. To date however, few studies have examined empirically what the impacts of different procurement models are across these multiple pillars of sustainability. This research aimed to fill the gap, by measuring and comparing the environmental, economic and nutritional outcomes of different models of school meals procurement. Case studies were undertaken of ten primary school meals services in five European countries, capturing different procurement model types. Results showed carbon emissions ranged from 0.95 kgs CO2e per meal in the lowest case to 2.41 kgs CO2e in the highest case, with adoption of low carbon food waste disposal methods and reduction of the amount of ruminant meat in the menus being the most important actions for lowering emissions. In terms of economic impact, local economic multiplier ratios ranged from 1.59 to 2.46, and although the level of local food sourcing contributed to these ratios, the effect was eclipsed, in some cases, by investment in local catering staff. Meanwhile, implementation of a robust standards regime and improving canteen environment and supervision were the most important actions for nutritional quality and intake. The paper discusses the implications of the findings for integrated, sustainable models of food procurement
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