Silicone hollow fiber membrane bioreactors for mixed aerobic and anaerobic treatment of gas phase toluene and trichloroethylene

Volatile Organic Compounds (VOCs) are common in effluent waste streams from many sectors of industry and low-cost emission control technologies have the potential to mitigate long-term impacts on the environment. Federal Regulations, such as the Clean Air Act and National Emission Standards for Hazardous Air Pollutants (NESHAPS), as well as state regulations are imposing stricter requirements on point-source emissions, with an emphasis on toxic VOCs. Trichloroethylene (TCE) and tetrachloroethylene (PCE), which are toxic VOCs, have been used since the 1920\u27s for a variety of industrial applications like: degreasing, paint and printing operations, as extraction solvents, and for cleaning and drying cleaning. Microbial degradation of many VOC can be facilitated using hollow fiber membrane bioreactors for a fraction of the cost of traditional control methods. Hollow fiber membrane bioreactors can provide mixed aerobic and anaerobic zones necessary for complete mineralization of alkene chlorinated solvents and allow for greater removal capacity for hydrophobic compounds than typical biological processes. In this work, two silicone hollow fiber membrane bioreactors were operated in parallel to develop loading curves for toluene removal and develop biomass for the subsequent degradation of TCE aerobically and anaerobically. The optimal toluene elimination capacity measured for each reactor varied from 55-60 mg m-2 hr-1 and no biotic TCE removal was observed. --Abstract, page iii

Динамика частотного реверса асинхронного двигателя

Для исследования реверсирования асинхронного двигателя сравниваются два способа частотной и противовключением. Анализируются различные законы изменения частоты статора и их влияние на быстродействие, пульсации момента, плавность

A new model of cosmogenic production of radiocarbon 14C in the atmosphere

We present the results of full new calculation of radiocarbon 14C production in the Earth atmosphere, using a numerical Monte-Carlo model. We provide, for the first time, a tabulated 14C yield function for the energy of primary cosmic ray particles ranging from 0.1 to 1000 GeV/nucleon. We have calculated the global production rate of 14C, which is 1.64 and 1.88 atoms/cm2/s for the modern time and for the pre-industrial epoch, respectively. This is close to the values obtained from the carbon cycle reservoir inventory. We argue that earlier models overestimated the global 14C production rate because of outdated spectra of cosmic ray heavier nuclei. The mean contribution of solar energetic particles to the global 14C is calculated as about 0.25% for the modern epoch. Our model provides a new tool to calculate the 14C production in the Earth's atmosphere, which can be applied, e.g., to reconstructions of solar activity in the past.Comment: Published in EPSL, 337, 114, 201

Tendenzen, Triebkräfte und Steuerungsmöglichkeiten der Entwicklung der Kulturlandschaft ländlicher Räume Baden-Württembergs

Die wesentlichen bei der Erarbeitung von Überblicken und Fallstudien sowie in der Diskussion gewonnenen Ergebnisse werden in vierzehn Punkten zusammengefasst, um die Bedeutung der Kulturlandschaft für die Entwicklung ländlicher Räume in Baden-Württemberg zu unterstreichen. Daraus ergeben sich Schlussfolgerungen für die räumliche Planung, aber auch neue Fragen und Aufgaben für die Forschung.The most important results derived from the work on the overviews, case studies and discussions are summarised in 14 points, underlining the significance of the cultural landscape for the development of rural spaces in Baden-Württemberg. This reveals consequences for spatial planning, but also new research questions and tasks

Nanoscale transient polarization gratings

We present the generation of transient polarization gratings at the nanoscale, achieved using a tailored accelerator configuration of the FERMI free electron laser. We demonstrate the capabilities of such a transient polarization grating by comparing its induced dynamics with the ones triggered by a more conventional intensity grating on a thin film ferrimagnetic alloy. While the signal of the intensity grating is dominated by the thermoelastic response of the system, such a contribution is suppressed in the case of the polarization grating. This exposes helicity-dependent magnetization dynamics that have so-far remained hidden under the large thermally driven response. We anticipate nanoscale transient polarization gratings to become useful for the study of any physical, chemical and biological systems possessing chiral symmetry

Indirect excitation of ultrafast demagnetization

Does the excitation of ultrafast magnetization require direct interaction between the photons of the optical pump pulse and the magnetic layer? Here, we demonstrate unambiguously that this is not the case. For this we have studied the magnetization dynamics of a ferromagnetic cobalt/palladium multilayer capped by an IR-opaque aluminum layer. Upon excitation with an intense femtosecond-short IR laser pulse, the film exhibits the classical ultrafast demagnetization phenomenon although only a negligible number of IR photons penetrate the aluminum layer. In comparison with an uncapped cobalt/palladium reference film, the initial demagnetization of the capped film occurs with a delayed onset and at a slower rate. Both observations are qualitatively in line with energy transport from the aluminum layer into the underlying magnetic film by the excited, hot electrons of the aluminum film. Our data thus confirm recent theoretical predictions