A simple method for the calculation of standard-graphs to be used in geo-electrical prospecting

Civil Engineering and Geoscience

Verslag behorende bij het fabrieksschema bereiding van wolfraam

Document(en) uit de collectie Chemische ProcestechnologieDelftChemTechApplied Science

Network optimization: A simple approach applying GIS and MLR

The collection of information (data) of a specific kind, in space and/or time is of major importance to the hydrologist. On regional scale, measurements of precipitation at several locations provide information of the input of a river catchment system. The study area with dimensions of 60 * 55.4 km2 , comprises 16 precipitation stations establishing a network. In general one can say that many experiments have been performed on gauged regions and many suggestions have been made relating the desired accuracy with the distance between the stations and the density of the network with the relief (WMO) , the local climatic conditions and the estimation of the study flood for a desired return period. Also it is proved that the increase of the network density is not always the best solution (even though one might not be so interested in the increase of costs). So the real problem is not only quantitative but qualitative as weIl and therefore more complex. This study dealt with the optimization of the existing network applying a mathematical- and a digital technique in combination with operational aspects. Although the influence of the individual approaches is difficult to quantify, conclusions which can be drawn are very satisfying; 2 stations can be abolished, 2 stations need to be re-equipped, for 3 stations the observer needs to be reconsidered. Also possible locations for new stations are distinguished. For composing the optimum network and rainfall-runoff relation ships additional research with more sophisticated digital techniques are requested.Water ManagementCivil Engineering and Geoscience

Assessing the overall life cycle impact of home energy management systems

An ever-increasing body of research explores the effectiveness of Home Energy Management systems (HEMS) in achieving energy savings. To date, however, the overall life cycle impact of the HEMS itself has not been taken into account. Thus, no assessment has been made whether the amount of energy saved (esaved) outweighs the energy needed for production, use and disposal (einvested). To determine whether esaved>einvested, a lifecycle assessment was conducted comparing three HEMS in six usage scenarios. The results show that the impact is dependent on the type of HEMS, and that the benefits do not always outweigh the (environmental) costs.Accepted Author ManuscriptOLD Housing SystemsDesign for Sustainabilit

Galacturonic Acid Inhibits the Growth of Saccharomyces cerevisiae on Galactose, Xylose, and Arabinose

The efficient fermentation of mixed substrates is essential for the microbial conversion of second-generation feedstocks, including pectin-rich waste streams such as citrus peel and sugar beet pulp. Galacturonic acid is a major constituent of hydrolysates of these pectin-rich materials. The yeast Saccharomyces cerevisiae, the main producer of bioethanol, cannot use this sugar acid. The impact of galacturonic acid on alcoholic fermentation by S. cerevisiae was investigated with anaerobic batch cultures grown on mixtures of glucose and galactose at various galacturonic acid concentrations and on a mixture of glucose, xylose, and arabinose. In cultures grown at pH 5.0, which is well above the pKa value of galacturonic acid (3.51), the addition of 10 g · liter?1 galacturonic acid did not affect galactose fermentation kinetics and growth. In cultures grown at pH 3.5, the addition of 10 g · liter?1 galacturonic acid did not significantly affect glucose consumption. However, at this lower pH, galacturonic acid completely inhibited growth on galactose and reduced galactose consumption rates by 87%. Additionally, it was shown that galacturonic acid strongly inhibits the fermentation of xylose and arabinose by the engineered pentose-fermenting S. cerevisiae strain IMS0010. The data indicate that inhibition occurs when nondissociated galacturonic acid is present extracellularly and corroborate the hypothesis that a combination of a decreased substrate uptake rate due to competitive inhibition on Gal2p, an increased energy requirement to maintain cellular homeostasis, and/or an accumulation of galacturonic acid 1-phosphate contributes to the inhibition. The role of galacturonic acid as an inhibitor of sugar fermentation should be considered in the design of yeast fermentation processes based on pectin-rich feedstocks.BiotechnologyApplied Science

Leakage-free rapid quenching technique for yeast metabolomics

Accurate determination of intracellular metabolite levels requires reliable, reproducible techniques for sampling and sample treatment. Quenching in 60% (v/v) methanol at ?40°C is currently the standard method for sub-second arrest of metabolic activity in microbial metabolomics but there have been contradictory reports in the literature on whether leakage of metabolites from the cells occurs. We have re-evaluated this method in S. cerevisiae using a comprehensive, strictly quantitative approach. By determining the levels of a large range of metabolites in different sample fractions and establishing mass balances we could trace their fate during the quenching procedure and confirm that leakage of metabolites from yeast cells does occur during conventional cold methanol quenching, to such an extent that the levels of most metabolites have been previously underestimated by at least twofold. In addition, we found that the extent of leakage depends on the time of exposure, the temperature and the properties of the methanol solutions. Using the mass balance approach we could study the effect of different quenching conditions and demonstrate that leakage can be entirely prevented by quenching in pure methanol at ??40°C, which we propose as a new improved method. Making use of improved data on intracellular metabolite levels we also re-evaluated the need of sub-second quenching of metabolic activity and of removing the extracellular medium. Our findings have serious implications for quantitative metabolomics-based fields such as non-stationary 13C flux analysis, in vivo kinetic modeling and thermodynamic network analysis.BiotechnologyApplied Science

Seasonal evaluation of the land surface scheme HTESSEL against remote sensing derived energy fluxes of the Transdanubian region in Hungary

Civil Engineering and Geoscience

Signal to Noise Ratio of APD-Based Monolithic Scintillator Detectors for High Resolution PET

Radiation, Radionuclides and ReactorsApplied Science