1,242 research outputs found

    Invariance quantum group of the fermionic oscillator

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    The fermionic oscillator defined by the algebraic relations cc^*+c^*c=1 and c^{2}=0 admits the homogeneous group O(2) as its invariance group. We show that, the structure of the inhomogeneous invariance group of this oscillator is a quantum group.Comment: 7 A4 page

    Properties of the one-dimensional Hubbard model: cellular dynamical mean-field description

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    The one-dimensional half-filled Hubbard model is considered at zero temperature within the cellular dynamical mean-field theory (CDMFT). By the computation of the spectral gap and the energy density with various cluster and bath sizes we examine the accuracy of the CDMFT in a systematic way, which proves the accurate description of the one-dimensional systems by the CDMFT with small clusters. We also calculate the spectral weights in a full range of the momentum for various interaction strengths. The results do not only account for the spin-charge separation, but they also reproduce all the features of the Bethe ansatz dispersions, implying that the CDMFT provides an excellent description of the spectral properties of low-dimensional interacting systems.Comment: J. Phys.: Condens. Matter, in pres

    Numerical modelling of mass transfer for solvent-carbon dioxide system at supercritical (miscible) conditions

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    A numerical procedure of mathematical model for mass transfer between a droplet of organic solvent and a compressed antisolvent is presented for conditions such that the two phases are fully miscible. The model is applicable to the supercritical antisolvent (SAS) method of particle formation. In this process, solute particles precipitate from an organic solution when sprayed into a compressed antisolvent continuum. Effects of operating temperature and pressure on droplet behavior were examined. The CO2 critical locus and the conditions for which the densities of solvent and carbon dioxide are equal are identified. Calculations were performed using Peng-Robinson equation of state. The model equations were put into the form that allowed the application of the Matlab standard solver pdepe. Calculations with toluene, ethanol, acetone (solvents) and carbon dioxide (antisolvent) demonstrated that droplets swell upon interdiffusion when the solvent is denser than the antisolvent and shrink when the antisolvent is denser. Diffusion modeling results might be used for data interpretation or experiments planning of the more complex real SAS process

    Textural and rheological properties of stevia ice cream

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    Ice cream contains high sugar content and therefore it is in contradiction with the concept of healthy diet. The objective of this study is to determine the suitability of using stevia as an alternative natural sweetener in making ice cream. In-house ice cream formulation (as the control) and three different concentrations of stevia ice cream formulations of (A, B and C) were used. Physical properties of the ice cream such as the overrun, total soluble solid, meltdown rate, rheology, and textural properties were evaluated. All ice cream samples exhibited a non-Newtonian flow with pseudoplastic behavior. Stevia ice cream has a lower melting rate and has a higher sustainability. The power law also showed that apparent viscosities of stevia ice cream were higher. Therefore, stevia can be used as a natural sugar substitute in ice cream production

    Effects of multi-stage dehumidified-air drying on the polyphenol content of Hydrocotyle bonariensis

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    Traditional drying methods involve high temperatures that degrade heat-sensitive compounds. Dehumidified-air drying, an alternative to traditional drying methods, is suitable for heat-sensitive compounds; however, it consumes a large amount of energy and is comparatively expensive. In this study, a multi-chamber dehumidified-air dryer was designed to dry Hydrocotyle bonariensis, and the retention of the polyphenol content of Hydrocotyle bonariensis under various drying conditions was examined. Multi-chamber dehumidified-air drying involves two chambers; each chamber was operated at temperatures of 30, 40, and 50°C with air volumetric flow rates of 30 and 50 L/min. The results indicated that the highest retention of total phenolic content and total flavonoid content, 24.67 mg of GAE/g dry weight (DW) and 2.204 mg of catechin/g DW, respectively, was obtained at 50°C with a 50 L/min air flow rate in the first drying chamber. Multi-stage dehumidified-air dryers have the potential to dry heat-sensitive products with reduced energy consumption

    Perancangan Sekolah Alam Bahari Bandar Bakau di Dumai

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    Green school is an informal school wich focus on character education for children about the preservation of the nature coast. For that the green school of bahari bandar bakau became a place in accordance with the curriculum of basic education to optimize green school of bandar bakau informal standards become formal. In the design this green school of bahari bandar bakau will be done with the contextual approach coastal architecture within the Dumai coastal areas, also uses the concept of archipelago built space values so that the green school can remember and demonstrated the importance values of the archipelago built space. Some indicators which become the state of the art is sustainablility, harmony of nature, the climate response, collective consciousness, intelligence and knowledge of the culture as a basic for generating design of green school in accordance with national curriculum standards and contextual with the maritime environment
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