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At least 127 records · Page 7Linked to original sources
PubMed1979

On the optimization of local hyperthermy in tumors based on a new radiofrequency procedure. Local hyperthermy of large body areas using the CMT selectotherm method.

A new radiofrequency procedure, i.c., the CMT Selectotherm technique, permits to convey large heat quantities per volume unit also to deep-seated tumor tissues without causing thermal lesions in healthy tissues near or at the body surface. The improved spatial homogeneity of energy supply attainable by this method is demonstrated by measurements at a gelatine phantom and, in particular, by in vivo measurements on pigs. The appliability of local hyperthermy to tumors localized in different parts of the body is substantially improved (a) by the principle of superimposing local hyperthermy on an elevated temperature level of metabolically induced whole-body hyperthermy (CMT-spontaneous hyperthermy at 40 degrees C) and (b) by the principle of selective increasing the thermal sensitivity of tumor tissues by decreasing the pH in these areas (the CMT main step). It is shown that the temperature dose T. deltat necessary for the selective occlusion of the vasculature in tumor tissues can be obtained by the CMT Selectotherm process also in deep-seated tumors. This process is part of the 1977 CMT concept. The fundamentals of optimizing local hyperthermy with consideration of heat dissipation from the tissue by heat conduction and convection via the blood stream are demonstrated. Temperature profiles are calculated for some practice-relevant, typical examples (inner and outer parts of sphero-symmetrically shaped tumors). Finally, in vivo measurements and calculations on the time course of temperature under certain conditions and for different tissue layers are discussed.

Bioelectric Energy Sources↗
PubMed1985

Low cost storing of two electrical biosignals from DC to 20 kHz at more than 80 dB dynamic range.

An instrumentation for storing electrical analog signals (DC to 20 kHz) was composed from a video recorder and a slightly modified pulse code modulation processor. As these components are mass products of the consumer electronics industry, the system price could be kept below 5000 DM. The setup allows one to register simultaneously two signals at DC to 20 kHz at a dynamic amplitude resolution of 16 bit [corresponding to a signal to noise ratio (S/N-ratio) of 96 dB] and AC-signals on the audiochannels of the stereo-video recorder. This is exemplified by recordings of insect chemoreceptors.

Bioelectric Energy Sources↗
PubMed1993

Electromagnetic wave emitting products and "Kikoh" potentiate human leukocyte functions.

Tourmaline (electric stone, a type of granite stone), common granite stone, ceramic disks, hot spring water and human palmar energy (called "Kikoh" in Japan and China), all which emit electromagnetic radiation in the far infrared region (wavelength 4-14 microns). These materials were thus examined for effects on human leukocyte activity and on lipid peroxidation of unsaturated fatty acids. It was revealed that these materials significantly increased intracellular calcium ion concentration, phagocytosis, and generation of reactive oxygen species in neutrophils, and the blastogenetic response of lymphocytes to mitogens. Chemotactic activity by neutrophils was also enhanced by exposure to tourmaline and the palm of "Kikohshi" i.e., a person who heals professionally by the laying on of hands. Despite the increase in reactive oxygen species generated by neutrophils, lipid peroxidation from unsaturated fatty acid was markedly inhibited by these four materials. The results suggest that materials emitting electromagnetic radiation in the far infrared range, which are widely used in Japan for cosmetic, therapeutic, and preservative purposes, appear capable of potentiating leukocyte functions without promoting oxidative injury.

Adolescent↗
PubMed2003

Enrichment of microbial community generating electricity using a fuel-cell-type electrochemical cell.

A fuel cell was used to enrich a microbial consortium generating electricity, using organic wastewater as the fuel. Within 30 days of enrichment the maximum current of 0.2 mA was generated with a resistance of 1 kOhms. Current generation was coupled to a fall in chemical oxygen demand from over 1,700 mg l(-1) down to 50 mg l(-1). Denaturing gradient gel electrophoresis showed a different microbial population in the enriched electrode from that in the sludge used as the inoculum. Electron microscopic observation showed a biofilm on the electrode surface and microbial clumps. Nanobacteria-like particles were present on the biofilm surface. Metabolic inhibitors and electron acceptors inhibited the current generation. 16S ribosomal RNA gene analysis showed a diverse bacterial population in the enrichment culture. These findings demonstrate that an electricity-generating microbial consortium can be enriched using a fuel cell and that the electrochemical activity is a form of anaerobic electron transfer.

Bacteria↗
PubMed2004

Principles of biorefineries.

Sustainable economic growth requires safe, sustainable resources for industrial production. For the future re-arrangement of a substantial economy to biological raw materials, completely new approaches in research and development, production and economy are necessary. Biorefineries combine the necessary technologies between biological raw materials and industrial intermediates and final products. The principal goal in the development of biorefineries is defined by the following: (biomass) feedstock-mix + process-mix --> product-mix. Here, particularly the combination between biotechnological and chemical conversion of substances will play an important role. Currently the "whole-crop biorefinery", "green biorefinery" and "lignocellulose-feedstock biorefinery" systems are favored in research and development.

Bioelectric Energy Sources↗
PubMed2005

Evaluation of procedures to acclimate a microbial fuel cell for electricity production.

A microbial fuel cell (MFC) is a relatively new type of fixed film bioreactor for wastewater treatment, and the most effective methods for inoculation are not well understood. Various techniques to enrich electrochemically active bacteria on an electrode were therefore studied using anaerobic sewage sludge in a two-chambered MFC. With a porous carbon paper anode electrode, 8 mW/m2 of power was generated within 50 h with a Coulombic efficiency (CE) of 40%. When an iron oxide-coated electrode was used, the power and the CE reached 30 mW/m2 and 80%, respectively. A methanogen inhibitor (2-bromoethanesulfonate) increased the CE to 70%. Bacteria in sludge were enriched by serial transfer using a ferric iron medium, but when this enrichment was used in a MFC the power was lower (2 mW/m2) than that obtained with the original inoculum. By applying biofilm scraped from the anode of a working MFC to a new anode electrode, the maximum power was increased to 40 mW/m2. When a second anode was introduced into an operating MFC the acclimation time was not reduced and the total power did not increase. These results suggest that these active inoculating techniques could increase the effectiveness of enrichment, and that start up is most successful when the biofilm is harvested from the anode of an existing MFC and applied to the new anode.

Alkanesulfonic Acids↗
PubMed2005

Proton exchange membrane and electrode surface areas as factors that affect power generation in microbial fuel cells.

Power generation in microbial fuel cells (MFCs) is a function of the surface areas of the proton exchange membrane (PEM) and the cathode relative to that of the anode. To demonstrate this, the sizes of the anode and cathode were varied in two-chambered MFCs having PEMs with three different surface areas (A (PEM)=3.5, 6.2, or 30.6 cm(2)). For a fixed anode and cathode surface area (A (An)=A (Cat)=22.5 cm(2)), the power density normalized to the anode surface area increased with the PEM size in the order 45 mW/m(2) (A (PEM)=3.5 cm(2)), 68 mW/m(2) (A (PEM)=6.2 cm(2)), and 190 mW/m(2) (A (PEM)=30.6 cm(2)). PEM surface area was shown to limit power output when the surface area of the PEM was smaller than that of the electrodes due to an increase in internal resistance. When the relative cross sections of the PEM, anode, and cathode were scaled according to 2A (Cat)=A(PEM)=2A (An), the maximum power densities of the three different MFCs, based on the surface area of the PEM (A (PEM)=3.5, 6.2, or 30.6 cm(2)), were the same (168+/-4.53 mW/m(2)). Increasing the ionic strength and using ferricyanide at the cathode also increased power output.

Bacteria, Anaerobic↗
PubMed2005

Utilization of keratin-containing biowaste to produce biohydrogen.

A two-stage fermentation system was constructed to test and demonstrate the feasibility of biohydrogen generation from keratin-rich biowaste. We isolated a novel aerobic Bacillus strain (Bacillus licheniformis KK1) that displays outstanding keratinolytic activity. The isolated strain was employed to convert keratin-containing biowaste into a fermentation product that is rich in amino acids and peptides. The process was optimized for the second fermentation step, in which the product of keratin fermentation--supplemented with essential minerals--was metabolized by Thermococcus litoralis, an anaerobic hyperthermophilic archaeon. T. litoralis grew on the keratin hydrolysate and produced hydrogen gas as a physiological fermentation byproduct. Hyperthermophilic cells utilized the keratin hydrolysate in a similar way as their standard nutrient, i.e., bacto-peptone. The generalization of the findings to protein-rich waste treatment and production of biohydrogen is discussed and possible means of further improvements are listed.

Aerobiosis↗
PubMed2006

Sustained generation of electricity by the spore-forming, Gram-positive, Desulfitobacterium hafniense strain DCB2.

Desulfitobacterium hafniense strain DCB2 generates electricity in microbial fuel cells (MFCs) when humic acids or the humate analog anthraquinone-2,6-disulfonate (AQDS) is added as an electron-carrying mediator. When utilizing formate as fuel, the Gram-positive, spore-forming bacterium generated up to 400 mW/m2 of cathode surface area in a single-chamber MFC with a platinum-containing air-fed cathode. Hydrogen, lactate, pyruvate, and ethanol supported electricity generation, but acetate, propionate, and butyrate did not. Scanning electron microscopy indicated that strain DCB2 colonized the surface of a current-generating anode but not of an unconnected electrode. The electricity was recovered fully within minutes after the exchange of the medium in the anode chamber and within a week after an exposure of a colonized anode to 90 degrees C for 20 min. Of the six strains of Desulfitobacteria tested, all of which would reduce AQDS, only D. hafniense strain DCB2 continued to reduce AQDS and generate electricity for more than 24 h, indicating that reduction of the humate analog alone is insufficient to sustain electrode reduction.

Anthraquinones↗
PubMed2005

Biogas production from crop residues on a farm-scale level: is it economically feasible under conditions in Sweden?

Anaerobic digestion would enable the energy potential of agricultural crop residues such as sugar beet tops and straw to be harnessed. Sweden is so spread out that full utilisation of this potential by centralised slurry-based technology is difficult. It appears that simple but effective high-solids reactor systems have a better chance of being economically viable on a farm-scale level (50-500 kW). In the present study, the financial prospects of high-solids digestion, using either single-stage fed-batch or two-stage batch reactor systems, are compared on a farm-scale level (50 kW) with those of conventional slurry digestion, on the basis of experimental results and observations on a laboratory- and pilot-scale. The gas produced can be used for heat, combined heat and power or as vehicle fuel. The results indicate high-solids single-stage fed-batch operations to stand the best chances of being competitive, particularly in connection with organic farming. The methane yield, degree of gas utilisation, and operational costs were found to have the strongest impact on the financial success of the process.

Anaerobiosis↗
PubMed2006

Biogas production from crop residues on a farm-scale level in Sweden: scale, choice of substrate and utilisation rate most important parameters for financial feasibility.

Anaerobic digestion would enable the energy potential of agricultural crop residues such as ley crops and sugar beet tops to be harnessed in Sweden. In the present study, the financial prospects of single-stage fed-batch high-solids digestion on three different scales, 51, 67, and 201 kW, were calculated on the basis of experimental results and observations. In addition to scale, the effects of methane yield and fertiliser recovery (compared to green manuring) was investigated by testing different substrate mixtures. The biogas was disposed as heat, combined heat and power, or as vehicle fuel. Besides the positive effect of scale, the results indicate the importance of choosing substrates with a high methane yield and high nitrogen content, and the necessity of fully utilising both the capacity of the equipment installed and the energy carriers produced. Net unit costs of 5.3 and 8.1 ct/kWh were achieved (201 kW), heat and vehicle fuel, respectively.

Anaerobiosis↗