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PubMed1991

Multipole expansions in the representation of current sources.

After obtaining the measured magnetic field or its components in the form of an isofield map one has to decide which approximation to use in solving the inverse problem. A single current dipole as an equivalent current source is often used. It will be shown when this approximation fails and one possible way to improve the equivalent source description. The expansion of current multipoles is discussed up to the second order. The localization of an equivalent current source in this case is considered. The application of this type of expansion is analysed and discussed.

Bioelectric Energy Sources↗
PubMed2002

Energy evaluation of forest residues originated from Eucalyptus globulus Labill in Galicia.

The possibility of retrieving the energy contained in forest residues originating from wood exploitation in Galicia (Spain) is evaluated. This study was made on Eucalyptus globulus Labill occupying a forest surface of 240000 ha. This species plays an important role in the economical development of Galicia, as it is the main forest species for production of pulp. Sampling was made over 1999 in seven different zones, three main stations plus four selected for comparison, situated in Galicia. The residues originating from cutting were sorted into three different groups and their calorific values were measured by static bomb calorimetry. These calorific values, close to 7200 kJ kg(-1), make possible the use of this residual biomass as an energy source. Calorific values were measured by static bomb calorimeter in an oxygen atmosphere. Flammability was determined using a standard epiradiator. Simultaneously, some other parameters, elementary chemical composition, heavy metal contents, moisture, density, ash percentage after combustion in the bomb, and main bioclimatic characteristics, were also determined.

Bioelectric Energy Sources↗
PubMed2002

Energy efficient production of hydrogen and syngas from biomass: development of low-temperature catalytic process for cellulose gasification.

The Rh/CeO2/M (M = SiO2, Al2O3, and ZrO2) type catalysts with various compositions have been prepared and investigated in the gasification of cellulose, a model compound of biomass, in a fluidized bed reactor at 500-700 degrees C. The conventional nickel and dolomite catalysts have also been investigated. Among the catalysts, Rh/CeO2/SiO2 with 35% CeO2 has been found to be the best catalyst with respect to the carbon conversion to gas and product distribution. The steam addition contributed to the complete conversion of cellulose to gas even at 600 degrees C. Lower steam supply gave the syngas and higher steam supply gave the hydrogen as the major product. Hydrogen and syngas from cellulose or cellulosic biomass gasification are environmentally super clean gaseous fuels for power generation. Moreover, the syngas derived liquid fuels such as methanol, dimethyl ether, and synthetic diesels are also super clean transportation fuels. However, the use of cellulose or cellulosic biomass for energy source through the gasification is challenging because of the formation of tar and char during the gasification process. It is interesting that no tar or char was finally formed in the effluent gas at as low as 500-600 degrees C using Rh/CeO2/SiO2(35) catalyst in this process.

Bioelectric Energy Sources↗
PubMed1978

[Recent progress in energy sources and in technology of electronic circuits (author's transl)].

Since 1957, when the first implantable pacemaker was developed, the performances of cardiac pacemakers have enormously improved. The paper describes the recent progress in the field of energy sources, technology and circuit solutions. The improvements achieved up to now have extended the mean life-time of an implantable pacemaker from about 30 months up to more than 6 years, while some pacemakers with programming capabilities are available and pacemakers with self-adapting capabilities to the individual hemodynamic needs are in the stage of advanced development.

Bioelectric Energy Sources↗
PubMed2004

Microbial communities associated with electrodes harvesting electricity from a variety of aquatic sediments.

The microbial communities associated with electrodes from underwater fuel cells harvesting electricity from five different aquatic sediments were investigated. Three fuel cells were constructed with marine, salt-marsh, or freshwater sediments incubated in the laboratory. Fuel cells were also deployed in the field in salt marsh sediments in New Jersey and estuarine sediments in Oregon, USA. All of the sediments produced comparable amounts of power. Analysis of 16S rRNA gene sequences after 3-7 months of incubation demonstrated that all of the energy-harvesting anodes were highly enriched in microorganisms in the delta-Proteobacteria when compared with control electrodes not connected to a cathode. Geobacteraceae accounted for the majority of delta-Proteobacterial sequences or all of the energy-harvesting anodes, except the one deployed at the Oregon estuarine site. Quantitative PCR analysis of 16S rRNA genes and culturing studies indicated that Geobacteraceae were 100-fold more abundant on the marine-deployed anodes versus controls. Sequences most similar to microorganisms in the family Desulfobulbaceae predominated on the anode deployed in the estuarine sediments, and a significant proportion of the sequences recovered from the freshwater anodes were closely related to the Fe(III)-reducing isolate, Geothrix fermentans. There was also a specific enrichment of microorganisms on energy harvesting cathodes, but the enriched populations varied with the sediment/water source. Thus, future studies designed to help optimize the harvesting of electricity from aquatic sediments or waste organic matter should focus on the electrode interactions of these microorganisms which are most competitive in colonizing anodes and cathodes.

Base Sequence↗
PubMed2005

Technology development for medical implants.

Work on new technologies for biomaterials and an implantable power source for implants is described here. Common requirements have been identified to start the development of technological solutions that can be applied to a range of products.

Biocompatible Materials↗
PubMed2004

Preliminary evaluation of fungicidal and termiticidal activities of filtrates from biomass slurry fuel production.

Biomass slurry fuel (BSF) production has recently been developed as a natural energy for the conversion of solid biomass into fuel. In addition to using fuel, filtrates from BSF production may also serve a chemical source with several organic compounds. There is an increasing interest in the research and application of biomass-based filtrates. In this study, fungicidal and termiticidal properties of filtrates from BSF production using sugi (Cryptomeria japonica) and acacia (Acacia mangium) wood were evaluated in laboratory decay and termite resistance tests. Wood blocks treated with the filtrates showed increased resistance against brown-rot fungus, Fomitopsis palustris. However the filtrates from sugi wood processed at 270 degrees C which contained less phenolic compounds than the other filtrates were effective against white-rot fungus, Trametes versicolor. Phenolic compounds of filtrates seemed to play a role in the decay resistance tests however the filtrates did not increase the durability of the wood blocks against subterranean termites Coptotermes formosanus. Despite high acetic and lactic acid content of the filtrates, vanillin content of the filtrates may have served as an additional food source and promoted termite attack. It can be concluded that filtrates with phenolic compounds from lignin degradation during BSF production can be considered for targeted inhibition of brown-rot.

Animals↗
PubMed2006

Microdiesel: Escherichia coli engineered for fuel production.

Biodiesel is an alternative energy source and a substitute for petroleum-based diesel fuel. It is produced from renewable biomass by transesterification of triacylglycerols from plant oils, yielding monoalkyl esters of long-chain fatty acids with short-chain alcohols such as fatty acid methyl esters and fatty acid ethyl esters (FAEEs). Despite numerous environmental benefits, a broader use of biodiesel is hampered by the extensive acreage required for sufficient production of oilseed crops. Therefore, processes are urgently needed to enable biodiesel production from more readily available bulk plant materials like sugars or cellulose. Toward this goal, the authors established biosynthesis of biodiesel-adequate FAEEs, referred to as Microdiesel, in metabolically engineered Escherichia coli. This was achieved by heterologous expression in E. coli of the Zymomonas mobilis pyruvate decarboxylase and alcohol dehydrogenase and the unspecific acyltransferase from Acinetobacter baylyi strain ADP1. By this approach, ethanol formation was combined with subsequent esterification of the ethanol with the acyl moieties of coenzyme A thioesters of fatty acids if the cells were cultivated under aerobic conditions in the presence of glucose and oleic acid. Ethyl oleate was the major constituent of these FAEEs, with minor amounts of ethyl palmitate and ethyl palmitoleate. FAEE concentrations of 1.28 g l(-1) and a FAEE content of the cells of 26 % of the cellular dry mass were achieved by fed-batch fermentation using renewable carbon sources. This novel approach might pave the way for industrial production of biodiesel equivalents from renewable resources by employing engineered micro-organisms, enabling a broader use of biodiesel-like fuels in the future.

Alcohols↗
PubMed1977

An implantable electromagnetic sound source for speech production.

Our goal is to provide laryngectomized cancer patients with a method of speech rehabilitation as an alternative to esophageal speech when required. With the cooperation of otolaryngologists, biomedical engineers, and speech therapists, an implantable electromagnetic sound source for voice production has been produced. It is biocompatible, durable, and functional in animal experimentation. A small, carefully selected clinical trial will soon begin.

Animals↗
PubMed2001

Hydrogen production. Green algae as a source of energy.

Hydrogen gas is thought to be the ideal fuel for a world in which air pollution has been alleviated, global warming has been arrested, and the environment has been protected in an economically sustainable manner. Hydrogen and electricity could team to provide attractive options in transportation and power generation. Interconversion between these two forms of energy suggests on-site utilization of hydrogen to generate electricity, with the electrical power grid serving in energy transportation, distribution utilization, and hydrogen regeneration as needed. A challenging problem in establishing H(2) as a source of energy for the future is the renewable and environmentally friendly generation of large quantities of H(2) gas. Thus, processes that are presently conceptual in nature, or at a developmental stage in the laboratory, need to be encouraged, tested for feasibility, and otherwise applied toward commercialization.

Bioelectric Energy Sources↗
PubMed1984

The chronically stimulated muscle as an energy source for artificial organs. Preliminary results of a basic study in sheep.

In 5 adult sheep the psoas muscle of one side was electrically stimulated through the muscle nerves with an implantable stimulation unit for more than 5 weeks. In the final experiments the isometric tetanic tension of the stimulated muscles was reduced to 50-70% of the contralateral normal muscle. The use of only 15 Hz as a stimulation frequency led to a transformation of the originally fast muscle into a slow muscle with more resistance to fatigue. Future application of the chronically stimulated psoas muscle for driving artificial organs is discussed.

Animals↗
PubMed1978

Current status of pacemaker power sources.

After years during which pacers of very similar design and capabilities were provided by a small number of manufactures, many different lithium, halogen, rechargeable, and nuclear power sources are now available. The variety of chemistries, methods of construction, and sealing techniques used in the batteries of the different manufacturers is almost unlimited. This has made it necessary for physicians who implant and follow pacer to acquire a general knowledge of the field if they are to make an informed choice of pacemaker power source for implantation and if they are to manage recalls with a minimum of patient and physician trauma. More experience is required before it can be definitely determined which of the new pacer power sources will prove superior, but when coupled with well-designed, hermetically sealed pulse generators, all are capable of providing continuous pacing for at least 5 years and the 10-year pacemaker is now a probability.

Animals↗
PubMed1975

Runaway pacemaker in seven patients: a persisting problem.

Runaway pacemaker has been encountered in 7 patients during the past 7 years at the Texas Heart Institute. In this series, 4 patients with fixed-rate pacemakers experienced pacemaker arrhythmias because of battery depletion, and 3 had arrhythmias because of component failure. Battery deterioration was heralded by an increase in cardiac rate. Ventricular tachycardia, rapidly followed by ventricular fibrillation, occurred in 2 patients. Prompt surgical exteriorization of the failing pulse generator and connection to an external pacemaker resulted in prompt recovery in all patients. Elective generator change should be performed routinely after 24 to 30 months unless reliable serial observations of ventricular rates can be attained. This at least will reduce the lethal complications attributed to battery exhaustion. Increasing developments in the design of generators and sources of power, as well as data from pacemaker clinic follow-up and telephone pulse transmittal, are expected to decrease the frequency of this complication.

Adult↗
PubMed1981

Approaches to the artificial heart. Invited speaker.

Over the last two decades, the implantable artificial heart has evolved from an idea to a device capable of completely supporting the circulation for periods now exceeding 5 months. Although initial animal studies were limited by thromboembolism and device breakage, the usual causes of death in experimental animals are now infection, atrioventricular valve obstruction, elastomer bladder calcification, or inadequate cardiac output because of the relatively rapid growth of the young calves. As a result of the bulky nature of the energy converter and the substantial risk of infection with large diameter percutaneous tubes, clinical use of their air-powered artificial hearts will be limited to patients who are awaiting or being prepared for heart transplantation. Artificial hearts with implanted energy converters are being developed for permanent heart replacement. These devices require well-designed, durable mechanical components and sophisticated control systems. Although initial designs centered around thermal engines powered by a completely implantable nuclear energy source, the excessive cost and potential dangers have shifted the focus away from the nuclear system. Several electrically driven artificial hearts, based on samarium-cobalt magnet brushless direct-current motors, are now undergoing bench testing and will be ready for long-term animal studies within 2 years. This research will culminate with the availability of an "off-the-shelf" electrically powered artificial heart for use in patients with a wide range of nonrepairable forms of end-stage heart disease.

Animals↗
PubMed1991

Mathematical aspects of source modeling.

This paper reviews the properties of the major source models which are used in the analysis of observed bioelectric signals in general, and of evoked potentials in particular. The interpretation of such models demands the solution of an associated inverse problem. Emphasis is laid on the possibility of imposing such constraints on the model which render stable inverse solutions and yet allow a physiological interpretation. The nature of this paper is tutorial.

Bioelectric Energy Sources↗
PubMed2005

In situ electrooxidation of photobiological hydrogen in a photobioelectrochemical fuel cell based on Rhodobacter sphaeroides.

In this paper, we present a photobiological fuel cell that utilizes the metabolic activity of living cells of Rhodobacter sphaeroides for the generation of electricity based on the in situ oxidation of photobiological hydrogen. Organic acids and alcohols contained in synthetic media as well as in fermented media of Escherichia coli K 12 served as the proton donor source for the photobiological hydrogen production by R. sphaeroides. We demonstrate thatthe photobiological hydrogen is efficiently oxidized in the microbial medium at electrocatalytic electrodes coated with a platinum-poly(3,4-ethylenedioxythiophene) (Pt-PEDOT) bilayer composite. The experimental results are discussed in terms of current and power output, substrate, and solar conversion efficiency.

Bioelectric Energy Sources↗
PubMed2004

Radiocarbon apportionment of fossil versus biofuel combustion sources of polycyclic aromatic hydrocarbons in the Stockholm metropolitan area.

Source-diagnostic markers and the isotopic composition of polycyclic aromatic hydrocarbons (PAHs) were examined in surface sediments from the greater Stockholm waterways to deduce the contribution from biomass sources to the environmental PAH load. The summed concentration of 20 PAHs ranged from 0.8 to 45.1 microg/g (dry weight) and exhibited a steep decline with increasing distance from the city center evidencing that sources within the metropolitan area of Stockholm dominate its PAH burden. Several diagnostic PAH ratios indicated an overwhelming predominance of pyrogenic sources over the petrogenic ones, while retene and 1,7-dimethylphenanthrene were unable to correctly evaluate the contribution from biomass combustion. The stable carbon isotope composition (delta13C) of individual PAHs ranged from -24.8 to -27.0% but also was proved inefficient to discriminate between different types of fuels due to the overlapping signals in various sources. The delta14C values of PAHs ranged between -550.4 and -934.1%, indicating a clear predominance of fossil fuel sources. By using an isotopic mass balance approach, we estimated that on average 17+/-9% of PAHs derived from biomass combustion. This radiocarbon apportionment, in conjunction with detailed energy statistics for the Stockholm region, revealed that the ambient PAH burden is roughly similar, per unit energy produced, from fossil fuels and biofuels. Societies' shifting energy policies toward a larger reliance on biofuels may thus not lead to further deterioration of air quality and respiratory ailments for the urban population.

Bioelectric Energy Sources↗
PubMed2002

Chapter two: methodologies for characterisation of combustion sources and for quantification of their emissions.

Emissions from the combustion of biomass and fossil fuels result in generation of a large number of particle and gaseous products in outdoor and/or indoor air, which create health and environmental risks. Of particular importance are the very small particles that are emitted in large quantities from all the combustion sources, and that could be potentially more significant in terms of their impact on health and the environment than larger particles. It is important to quantify particle emissions from combustion sources for regulatory and control purposes in relation to air quality. This paper is a review of particle characteristics that are used as source signatures, their general advantages and limitations, as well as a review of source signatures of the most common combustion pollution sources including road transport, industrial facilities, small household combustion devices, environmental tobacco smoke, and vegetation burning. The current methods for measuring particle physical characteristics (mass and number concentrations) and principles of methodologies for measuring emission factors are discussed in the paper as well. Finally, the paper presents the recommendations for the future techniques for measurements of combustion products.

Air Movements↗