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We present a two dimensional (2D) planar chromatographic separation of estrogenic active compounds on RP-18 (Merck, 1.05559) and silica gel (Merck, 1.05721) phase. A mixture of 13 substances was separated using a solvent mix consisting of methanol–acetonitrile–water (2 + 2 + 1, v/v/v) on RP-18 phase in the first direction and cyclohexane–butylacetate–methanol (8 + 6 + 1, v/v/v) in the second direction on silica gel plate. Both developments were carried out over a distance of 70 mm. We used the grafted method to combine both plates in a 2D-separation. This 2D-separation method can be used to quantify 17α-ethinylestradiol (EE2) in an effect-directed analysis using the yeast strain Saccharomyces cerevisiae BJ3505. The test strain (according to McDonnell) contains the estrogen receptor. Its activation by estrogen active compounds is measured by inducting the reporter gene lacZ that encodes the enzyme ß-galactosidase. This enzyme activity is determined on plate by using the fluorescent substrate MUG (4-methylumbelliferyl ß-D-galactopyranoside).
An Extraction Method for 17α-Ethinylestradiol from Water using a new kind of monolithic Stir-bar
(2015)
Passive solar elements for both direct and indirect gains, are systems used to maintain a comfortable living environment while saving energy, especially in the building energy retrofit and adaptation process. Sunspaces, thermal mass and glazing area and orientation have been often used in the past to guarantee adequate indoor conditions when mechanical devices were not available. After a period of neglect, nowadays they are again considered as appropriate systems to help face environmental issues in the building sector, and both international and national legislation takes into consideration the possibility of including them in the building planning tools, also providing economic incentives. Their proper design needs dynamic simulation, often difficult to perform and time consuming. Moreover, results generally suffer from several uncertainties, so quasi steady-state procedures are often used in everyday practice with good results, but some corrections are still needed. In this paper, a comparative analysis of different solutions for the construction of verandas in an existing building is presented, following the procedure provided by the slightly modified and improved Standard EN ISO 13790:2008. Advantages and disadvantages of different configurations considering thermal insulation, windows typology and mechanical ventilation systems are discussed and a general intervention strategy is proposed. The aim is to highlight the possibility of using sunspaces in order to increase the efficiency of the existing building stock, considering ease of construction and economic viability.
Energy Performance of Verandas in the Building Retrofit Process (PDF Download Available). Available from: https://www.researchgate.net/publication/303093420_Energy_Performance_of_Verandas_in_the_Building_Retrofit_Process [accessed Jul 5, 2017].
The current methods used to assess the energy performance of ventilation devices do not consider all the aspects necessary for a comprehensive evaluation of decentralised ventilation concepts and can only be partially adapted to their needs. In order to improve the energy evaluation and to ensure the comparability of different systems, a calorimetric method was developed and implemented in test facilities for the evaluation of two decentralised devices: one equipped with a recuperative counter flow heat exchanger and one with a regenerative heat exchanger. This method, based on direct measurements of the heating load in an insulated test room, includes the effect of the electrical consumption of the fans on the energy performance of the ventilation devices. The calorimetric evaluation method was extended to a seasonal evaluation on the basis of a heating-degree-day method implemented for a warm, a cool and a moderate location in Europe: Athens, Strasbourg and Copenhagen. All the results are above 50% efficiency for both devices, even in Athens where the use of heat recovery ventilation is not usual.
In the present study, in vitro toxicity as well as biopersistence and photopersistence of four artificial sweeteners (acesulfame, cyclamate, saccharine, and sucralose) and five antibiotics (levofloxacin, lincomycin, linezolid, marbofloxacin, and sarafloxacin) and of their phototransformation products (PTPs) were investigated. Furthermore, antibiotic activity was evaluated after UV irradiation and after exposure to inocula of a sewage treatment plant. The study reveals that most of the tested compounds and their PTPs were neither readily nor inherently biodegradable in the Organisation for Economic Co-operation and Development (OECD)-biodegradability tests. The study further demonstrates that PTPs are formed upon irradiation with an Hg lamp (UV light) and, to a lesser extent, upon irradiation with a Xe lamp (mimics sunlight). Comparing the nonirradiated with the corresponding irradiated solutions, a higher chronic toxicity against bacteria was found for the irradiated solutions of linezolid. Neither cytotoxicity nor genotoxicity was found in human cervical (HeLa) and liver (Hep-G2) cells for any of the investigated compounds or their PTPs. Antimicrobial activity of the tested fluoroquinolones was reduced after UV treatment, but it was not reduced after a 28-day exposure to inocula of a sewage treatment plant. This comparative study shows that PTPs can be formed as a result of UV treatment. The study further demonstrated that UV irradiation can be effective in reducing the antimicrobial activity of antibiotics, and consequently may help to reduce antimicrobial resistance in wastewaters. Nevertheless, the study also highlights that some PTPs may exhibit a higher ecotoxicity than the respective parent compounds. Consequently, UV treatment does not transform all micropollutants into harmless compounds and may not be a large-scale effluent treatment option.
This paper presents the results of the idea generation experiment that repeats the study originally conducted at RMIT. In order to establish the influence that the experimental treatments make on the number and the breadth of solution ideas proposed by problem solvers with different knowledge levels, students from different years of study were recruited. Ninety students from the Offenburg University of Applied Sciences, Germany were divided into three groups. All students were asked to generate ideas on cleaning lime deposits from the inside of a water pipe and were given 16 minutes to record their individual ideas. Students of two experimental groups were shown some words for two minuted each. The Su-Field group was exposed to the eight fields of MATCEMIB. The Random Word group was shown eight random words every two minutes. The Su-Field group outperformed both the Control group and the Random Word group in the number of ideas generated. It was also found that the students from the Su-Field group proposed significantly broader solutions than the students from the Control and Random Word groups. The overall results of the experiment support the conclusions made by the RMIT researchers that simple ideation techniques can significantly improve idea generation and that the systematised Substance-Field Analysis is a suitable heuristic for engineering students.
The state-of-the-art electrochemical impedance spectroscopy (EIS) calculations have not yet started from fully multi-dimensional modeling. For a polymer electrolyte membrane fuel cell (PEMFC) with long flow channel, the impedance plot shows a multi-arc characteristic and some impedance arcs could merge. By using a step excitation/Fourier transform algorithm, an EIS simulation is implemented for the first time based on the full 2D PEMFC model presented in the first part of this work. All the dominant transient behaviors are able to be captured. A novel methodology called ‘configuration of system dynamics’, which is suitable for any electrochemical system, is then developed to resolve the physical meaning of the impedance spectra. In addition to the high-frequency arc due to charge transfer, the Nyquist plots contain additional medium/low-frequency arcs due to mass transfer in the diffusion layers and along the channel, as well as a low-frequency arc resulting from water transport in the membrane. In some case, the impedance spectra appear partly inductive due to water transport, which demonstrates the complexity of the water management of PEMFCs and the necessity of physics-based calculations.
A two-dimensional single-phase model is developed for the steady-state and transient analysis of polymer electrolyte membrane fuel cells (PEMFC). Based on diluted and concentrated solution theories, viscous flow is introduced into a phenomenological multi-component modeling framework in the membrane. Characteristic variables related to the water uptake are discussed. A Butler–Volmer formulation of the current-overpotential relationship is developed based on an elementary mechanism of electrochemical oxygen reduction. Validated by using published V–I experiments, the model is then used to analyze the effects of operating conditions on current output and water management, especially net water transport coefficient along the channel. For a power PEMFC, the long-channel configuration is helpful for internal humidification and anode water removal, operating in counterflow mode with proper gas flow rate and humidity. In time domain, a typical transient process with closed anode is also investigated.
Gas adsorption studies of CO2 and N2 in spatially aligned double-walled carbon nanotube arrays
(2013)
Gas adsorption studies (CO2 and N2) over a wide pressure range on vertically, highly aligned dense double-walled carbon nanotube arrays of high purity and high specific surface area are reported. At high pressures, the adsorption capacity of these materials was found to be comparable to those of metal organic frameworks and mesoporous molecular sieves. These highly aligned CNT arrays were chemically modified by treating with oxygen plasma and structurally modified by decreasing the diameter of individual carbon nanotubes. Oxygen plasma treatment led to grafting of a large number of C–O functional groups onto the CNT surface, which further increased the gas adsorption capacity. It was found that gas adsorption is dependent on tube diameter and increases with decrease of the individual CNT diameter in the CNT bundles. As results of our studies we have found that at lower pressure regimes, plasma functionalized carbon nanotubes exhibit better adsorption characteristics whereas at higher pressures, lower diameter carbon nanotube structures exhibited better gas adsorption characteristics.
We present a 3D simulation approach utilising the diffuse interface representation of the phase-field method combined with a heat transfer equation to analyse the thermal conductivity in air-filled aluminium foams with complex cellular structures of different porosity. Algorithmic methods are introduced to create synthetic open-cell foam structures and to compute the thermal conductivity by means of phase-field modelling. A material law for the effective thermal conductivity is derived by determining the appropriate exponent depending on the relative density in the system. The results are compared with the thermal conductivity in massive aluminium and in pure air.