Iskanje po katalogu digitalne knjižnice

Opis: Hydrogen is expected to become an important fuel in the long-term since in combination with fuel cells it offers the opportunity of an intrinsically clean energy supply. By application of supercritical water gasification (SCWG) concept, sustainable hydrogen can be produced from biomass and waste. The paper offers an overview of some recently published papers dealing with SCWG of model compounds and a summary of the investigations on SCWG of real agricultural and food processing wastes. In the frame of our work an intense research was performed to support analyses of SCWG of glycerol and was supported by the investigation of phase equilibrium for the systems gas/water and gas mixtures/water. When glycerol/water solutions were directly injected in the reactor operating at supercritical conditions, gases with high C2+ were obtained by the reforming in supercritical water unit. To reduce the hydrocarbon concentrations and to obtain a syngas with higher CO/CO2 ratios from a mixture of gases (H2, CO, CO2 and CH4), catalytic reactions at high pressure and temperature were introduced reflecting in an increase of the content of H2 and CO. Solubility measurements were conducted for the binary systems of gas and water at elevated pressures and temperatures.
Ključne besede: biogas, SCF technology, biotechnology
Objavljeno v DKUM: 19.07.2017; Ogledov: 923; Prenosov: 188
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Opis: The tremendous development of science and technology has influenced many aspects of our everyday lives, society and environment. A good example of such technology is biotechnology. However, besides its promise, this technology has also raised several controversial issues to which answers are not easily available. With increasing knowledge and applications on one side and controversy on the other the teaching of science is, anything but easy. Development of competencies for these issues, and questions like why, when, and how to integrate modern biotechnology into science education are becoming prominent in the near future. Nowadays, when we are confronted with issues of varying degrees of complexity and importance, it is necessary that teachers at all levels of education have the basic tools to cope with these issues. This is one of reason why we have attempted to establish what kind of knowledge, values and opinions about genetic engineering and genetically modified organisms (GMOs) are characteristic for the students, future Elementary Teachers, at three Slovene Faculties of Education. We collected answers of 360 questionnaires from pre-service elementary school teachers and analysed their statements from the field of general and classical genetics, modern biotechnology, legislation and the acceptance of different kind of GMOs. Prospective teachers have some knowledge of general and classical genetics and less knowledge about the use of modern biotechnology. They have concerns and fears about different kind of GMOs, mostly negative attitudes towards different kinds of GMOs, or they hold no strong opinions about them. Microorganisms and plants are generally more acceptable than GM animal. Furthermore, more knowledge does not mean that individual GMOs are more acceptable.
Ključne besede: genetically modified organisms, GMO, students of elementary education, biotechnology, knowledge
Objavljeno v DKUM: 21.12.2015; Ogledov: 1777; Prenosov: 42
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Opis: The objective of this study was to investigate knowledge, opinions, and attitudes toward, as well as readiness to accept genetically modified organisms (GMOs) among prospective primary and secondary Slovene teachers. Our findings are that prospective teachers want to take an active role in rejecting or supporting individual GMOs and are aware of the importance of education about genetically modified organism (GMO) items and their potential significance for society. Through cluster analysis, we recognized four clusters of GMOs, separated by degree of genetically modified acceptability. GM plants and microorganisms which are recognized as useful are accepted. They are undecided about organisms used in research or medicine and reject organisms used for food consumption and for fun. There are only weak correlations between knowledge and attitudes and knowledge and acceptance of GMOs, and a strong correlation between attitudes and acceptance. The appropriate strategies and actions for improving university courses in biotechnology are discussed.
Ključne besede: biotechnology, genetic modifications, genetically modified organisms, acceptance, attitudes, education
Objavljeno v DKUM: 07.06.2012; Ogledov: 2031; Prenosov: 98
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Opis: Fatty ester synthesis with immobilized 1,3-specific lipase from Mucor Miehei is described. 1,2-Isopropylidene glycerol was peoduced by condensation of glycerol with acetone was esterified with oleic acid in the presence of a Mucor Miehei lipaze (Lipozyme TM) to obtain 1,2 isopropylidene- 3-oleoyl glycerol. The effects of various process parameters (temperature and pressure)and various ratios (enzyme/substrate) have been investigated to determine optimal conditions for the esterification process. The highest conversion of oleic acid (80% w/w) was obtained at 55 oC and 57.057 bar, while the optimal addition of lipase to substrate was determined to be 0,096 g per gram of reaction mixture. The esterification can be modelled successfully as a reverse second order reaction. Thermodynamic properties of the reaction system at 55 oC and 0.057 bar were also determined. Activation energy was 20.82 kJ/mole, entropy of activation -0,26 kJ/(Kmole) and free energy of activation was 103.32 kJ/mole.
Ključne besede: chemical engineering, biotechnology, esterification, syntheses, esters, enzymes, lipase, Mucor miehei, reaction kinetics, reaction thermodynamics, 1, 2-isopropylidene-3-oleoyl glycerol
Objavljeno v DKUM: 06.06.2012; Ogledov: 2226; Prenosov: 95
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Opis: This article gives a summary of the most commonly used ecologically unfriendly processes for the reduction and oxidation of vat and sulphur dyes. It also describes the new alternatives that are in the development stage and could be important in the near future. Sodium dithionite as the dominant reducing agent produces large amounts of sodium sulphate, and also toxic sulphite and thiosulphate as by-products. Consequently, high amounts of hydrogen peroxide and alkali are required for the treatment of effluents, which add to the cost of the process. Attempts have been made to use organic biodegradable reducing agents, enzymes, catalytic hydrogenation, and also indirect or direct, electrochemical reductive methods that employ a redox mediator (electron-carrier). The reduction has also been carried out via the dye radical molecule or, in the case of indigo, by direct electrochemical reduction using graphite as the electrode material. Physical techniques, for example using ultrasound, magnetic fields or UV have been shown to be effective only when used to accelerate methods using classical reduction and oxidation processes. However, although these methods offer some environmental benefits, there is still no satisfactory alternative reducing and/or oxidising agent available today.
Ključne besede: textile dyeing, vat dyes, sulphur dyes, reduction, oxidation, catalysis, ecology, organic agents, electrochemistry, ultrasound, magnetic field, UV application, biotechnology
Objavljeno v DKUM: 01.06.2012; Ogledov: 2813; Prenosov: 114
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