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PubMedDate not supplied

A new skeletal muscle linear-pull energy convertor as a power source for prosthetic circulatory support devices [corrected].

Previous studies show that stimulated skeletal muscle wrapped around the heart or a blood pumping pouch can provide partial circulatory assistance. However, skeletal muscle is accustomed to pulling in direct tension, and power obtained from using the muscle in wraparound configurations is very inefficient. Therefore we have developed a new skeletal muscle-powered, linear-pull energy convertor for powering a wide range of implanted devices, including circulatory support blood pumps such as counterpulsation devices or complete prosthetic ventricles. This energy convertor system is powered by a skeletal muscle such as the latissimus dorsi, which is stimulated with a pulse generator. With the muscle left intact and in situ as much as possible, its insertion at the humerus is removed and reattached to a small-cylinder hydraulic energy convertor that is firmly attached to the ribs. Mechanical force in direct tension from the muscle is converted to high-pressure, low displacement; hydraulic energy (at approximately 200 psi). The output of this hydraulic energy convertor is connected by a small-diameter tube to a hydraulic actuator to drive the pusher plate of an implantable ventricular assist device located in the thoracic cavity or abdomen or another suitable blood pump. Preliminary in vitro tests from an engineering model of the Thoratec muscle-powered ventricular assist device show flow outputs of 5.2 L/min at a mean arterial pressure of 99 mm Hg. The muscle-powered ventricular assist device is a specific application designed to provide completely implantable circulatory support as an alternative to heart transplantation. It will enable patients to experience a quality of life free from batteries and the electrical power-conditioning hardware required with electromechanical systems.

Bioelectric Energy Sources↗
PubMed2003

Unconverted chars obtained during biomass gasification on a pilot-scale gasifier as a source of activated carbon production.

Biomass gasification was used to produce activated carbon on a pilot-scale fluidised-bed gasifier. The feedstock included both biomass alone and biomass mixed with coal and coal/granulated plastic wastes. This paper reports the results obtained from four different runs undertaken under various conditions of fuel supply, different ratios of steam/air for the gasification and temperature. These conditions were selected because they led to a significant amount of unconverted chars produced during gasification (from 0.72 to 1.4 kg) which then served as raw material for the production of activated carbon whilst the amount of gas obtained was also high enough for its potential use for different end-use applications. From the analysis of the results obtained, it can be concluded that a reasonable porosity development (mainly in the area of narrow micropores) was obtained by gasifying unblended pine wastes with steam for 4 h, producing about 1.4 kg of good-quality activated carbon (micropore volume of 0.263 cm(3)/g). In other runs, chars with a reduced microporosity development (i.e. 0.180 cm(3)/g) were obtained, however, they could be used as a proper starting material for the chemically activated carbon production.

Bioelectric Energy Sources↗
PubMed2006

Safety evaluation for a biodiesel process using prion-contaminated animal fat as a source.

BACKGROUND: Due to the bovine spongiform encephalopathy (BSE), specified risk material (SRM) as well as animal meat and bone meal (MBM) are banned from the food and feed chain because of a possible infection with pathogenic prions (PrP(Sc)). Nowadays, prions are widely accepted to be responsible for TSE(transmissible spongiform encephalopathies)-caused illnesses like BSE and scrapie, and especially for the occurrence of the new variant of CJD in humans. Presently, SRM and MBM are burnt under high temperatures to avoid any hazards for humans, animals or the environment. The aim of this study was to evaluate a method using animal fat separated from Category I material which includes SRM and the carcasses of TSE-infected animals, or animals suspected of being infected with TSE, as a source for producing biodiesel by transesterification, analogous to the biodiesel process using vegetable oil. METHODS: For this purpose, animal fat was spiked with scrapie-infected hamster brain equivalents--as representative for a TSE-infected animal--and the biodiesel manufacturing process was downscaled and performed under lab-scale conditions. RESULTS AND DISCUSSION: The results analysed by Western blotting showed clearly that almost each single step of the process leads to a significant reduction of the concentration of the pathogenic prion protein (PrP(Sc)) in the main and side-products. CONCLUSION: The data revealed that the biodiesel production, even from material with a high concentration of pathogenic prions, can be considered as safe. RECOMMENDATIONS AND OUTLOOK: The obtained results indicated that biodiesel produced from prion-contaminated fat was safe under the tested process conditions. However, it has to be pointed out that the results cannot be generalized because a different process control using other conditions may lead to different results and then has to be analysed independently. It is clear that the production of biodiesel from high risk material represents a more economic usage than the combustion of such material.

Animals↗
PubMedDate not supplied

Pulmonary artery counterpulsation with a skeletal muscle power source.

We evaluated the feasibility of using skeletal muscle (SM) to provide pulmonary artery (PA) counterpulsation in an acute pulmonary hypertension (PHT) model. PA counterpulsation was achieved in six dogs with a dual chambered pump powered by the latissimus dorsi muscle. A rate-responsive stimulator was used to make the muscle contract in counterpulsation. Graded PHT was induced by infusing 150 microns glass beads into the PA, while RV and PA pressures were monitored. With PA pressures ranging from 19/10 to 115/62 mmHg, effective counterpulsation was observed. The degree of counterpulsation was influenced by the extent of PHT induced, with the amount of RV tension-time index (TTI) unloading correlated with the level of PA systole (r = 0.92). Therefore, results were divided into two groups (Group 1: PA systole less than or equal to 40 mmHg, and Group 2: PA systole greater than 40 mmHg). In Group 1, RV TTI decreased from 11.29 +/- 0.76 to 9.99 +/- 0.72 mmHg.sec, PA diastole increased from 20 +/- 2.3 to 31 +/- 3.0 mmHg, and PA mean increased from 24 +/- 2.2 to 2.9 +/- 2.2 mmHg (all p less than 0.05). In Group 2, RV TT1 decreased from 15.12 +/- 1.83 to 10.99 +/- 0.90 mmHg.sec, PA diastole increased from 41 +/- 3.5 to 64 +/- 6.2 mmHg, and PA mean increased from 49 +/- 4.8 to 55 +/- 5.7 mmHg (all p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2006

Making glucose oxidase fit for biofuel cell applications by directed protein evolution.

Progress in miniature chip-design raises demands for implantable power sources in health care applications such as continuous glucose monitoring of diabetic patients. Pioneered by Adam Heller, miniaturized enzymatic biofuel cells (mBCs) convert blood sugars into electrical energy by employing for example glucose oxidase (GOx) on the anode and bilirubin oxidase on the cathode. To match application demands it is crucial to increase lifetime and power output of mBCs. The power output has been limited by the performance of GOx on the anode. We developed a glucose oxidase detection assay (GODA) as medium-throughput screening system for improving GOx properties by directed protein evolution. GODA is a reaction product detection assay based on coupled enzymatic reactions leading to NADPH formation which is recorded at 340 nm. The main advantage of the assay is that it detects the production of d-gluconolactone instead of the side-product hydrogen peroxide and enables to improve bioelectrochemical properties of GOx. For validating the screening system, a mutagenic library of GOx from Aspergillus niger (EC 1.1.3.4) was generated and screened for improved activity using Saccharomyces cerevisiae as host. Directed evolution resulted in a GOx mutant I115V with 1.4-1.5-fold improved activity for beta-d-glucose (Vmax from 7.94 to 10.81 micromol min(-1) mg(-1); Km approximately 19-21 mM) and oxygen consumption kinetics correlate well [Vmax (O2) from 5.94 to 8.34 micromol min(-1) mg(-1); Km (O2) from 700 to 474 microM]. The developed mutagenic protocol and GODA represent a proof-of-principle that GOx can be evolved by directed evolution in S. cerevisiae for putative use in biofuel cells.

Bioelectric Energy Sources↗
PubMed2004

Methane-dependent denitrification by a semi-partitioned reactor supplied separately with methane and oxygen.

Methane (CH4) can be used as an alternative carbon source for denitrification with added oxygen (O2). However, the off-gas of denitrification reactors using a CH4-O2 mixture contains unused CH4 and O2 in proportions that make it unusable for fuel, carry explosion risks, and, if released into the atmosphere, contribute to the greenhouse effect. This study tested a novel reactor with a partition dividing the headspace completely and extending partly into the liquid layer. When CH4 and O2 were supplied separately to the liquid layer on opposite sides of the partition, the methane-dependent denitrification (MDD) activity was similar to that when the two gases were supplied as a mixture. In reactors with separate gas supplies, the off-gas from the CH4 supply side was high in CH4 and low in O2, and was usable for fuel, and that from the O2 supply side was very low in CH4, and might be released into the atmosphere. MDD activity increased with the O2 supply rate, and separate discharge of CH4 and O2 was maintained. The concentration of dissolved methane in the effluent was decreased by lowering the CH4/O2 supply ratio to 1.0 and drawing the effluent from the O2 supply side. This novel reactor enhances the safety of MDD, allows reuse of methane as fuel, and reduces methane leakage to the atmosphere.

Air Pollution↗
PubMed1976

Hyaluronidase-bound membrane as a biomaterial for implantable fuel cells.

A new biomaterial containing covalently bound hyaluronidase was prepared. An application of this enzyme membrane is to improve the performance of an implantable fuel cell. Hyaluronic acid is a contributor to the viscosity of tissue fluids but can be a potential fuel source because of its sugar content. The incorporation of immobilized hyaluronidase would not only contribute to a more available fuel supply by splitting hyaluronic acid but, perhaps more importantly, enhance the rate of mass transport of fuel, O2, and reaction products by reducing the viscosity near the electrode membranes. Hyaluronidase was bound to Sepharose gel and its thermoplastic membrane after activation by cyanogen bromide. Fourteen and 22% of the activities were recovered from the gel and membrane, respectively. The activity of the bound enzyme was stable for six months at 0 degrees C. The addition of hyaluronic acid, 1 mg/ml, to a typical implantable type bioautofuel cell in vitro increased external solution viscosity from 1.1 to 2.5-2.8 cP and reduced voltage output under 10 komega by 60% in 3 hr. When the hyaluronidase bound membrane was placed at the anode, viscosity of the glucose-hyaluronic acid solution was lowered to 1.8 cP and the cell output increased to the original level of a glucose-fueled cell in 3 hr. Glucosamine-equivalent released from hyaluronic acid at the electrode was 3.1 mg after 22.5 hr. This represents 90% of the theoretical consumption. Restoration of the cell output was probably a combination of the enhanced transport of fuel, O2 and products, and/or appearance of a new fuel, glucosamine-equivalent.

Biocompatible Materials↗
PubMed1976

Chronic testing of a pacemaker that needs recharging only once every four years.

Since 1967, three series of rechargeable single-cell silver-mercuric oxide-zinc pacemakers have been implanted in dogs with complete heart block. The five nonhermetic units in series 1 failed after less than or equal to 18 months, primarily due to prototype cell deficiencies, although one cell functioned for eight years. The six units in series II contained improved cells, but failed due to gradual transepoxy fluid absorption after less than or equal to 31 months. All rechargeable cells were salvaged and dried, and, seven years after their manufacture, they continue to power pacing circuits. Series III now totals 20 doubly hermetically sealed units, tested for up to three years (total more than 300 months or 26 years), with no pacemaker failures. Accelerated tests indicate a minimum life of more than 50 years. A clinical trial is in progress.

Animals↗
PubMed2005

Sims characterization of La0.7Sr0.3MnO3 films for solid oxide fuel cell applications.

Among solid oxides exploited to prepare efficient fuel cells, La(1-x)SrxMnO3 manganites have been widely studied and used as cathodes, because of their high conductivity at the working temperatures, good thermal stability and compatibility with other cell components. A fundamental goal in solid oxide fuel cells technology consists in lowering the normal operating temperatures, e.g. increasing the surface/volume ratio of electrodic materials, so as to enhance their catalytic performances. In this work, the preparation of high surface area La(1-x)SrxMnO3 (x approximately 0.3) films on silicon wafers by the nitrate-citrate Pechini process is described. The films were characterized by X-ray diffraction, Atomic Force Microscopy and Secondary Ion Mass Spectrometry. Good quality nanostructured perovskite-type films were obtained. SIMS methodology enabled to show the surface and in-depth coatings composition and residual contaminants. Moreover, it allowed defining the best synthesis conditions for complete in-depth decomposition of precursors and obtaining homogeneously thick coatings.

Bioelectric Energy Sources↗
PubMed2003

Improved fuel cell and electrode designs for producing electricity from microbial degradation.

A new one-compartment fuel cell was composed of a rubber bunged bottle with a center-inserted anode and a window-mounted cathode containing an internal, proton-permeable porcelain layer. This fuel cell design was less expensive and more practical than the conventional two-compartment system, which requires aeration and a ferricyanide solution in the cathode compartment. Three new electrodes containing bound electron mediators including a Mn(4+)-graphite anode, a neutral red (NR) covalently linked woven graphite anode, and an Fe(3+)-graphite cathode were developed that greatly enhanced electrical energy production (i.e., microbial electron transfer) over conventional graphite electrodes. The potentials of these electrodes measured by cyclic voltametry at pH 7.0 were (in volts): +0.493 (Fe(3+)-graphite); +0.15 (Mn(4+)-graphite); and -0.53 (NR-woven graphite). The maximal electrical productivities obtained with sewage sludge as the biocatalyst and using a Mn(4+)-graphite anode and a Fe(3+)-graphite cathode were 14 mA current, 0.45 V potential, 1,750 mA/m(2) current density, and 788 mW/m(2) of power density. With Escherichia coli as the biocatalyst and using a Mn(4+)-graphite anode and a Fe(3+)-graphite cathode, the maximal electrical productivities obtained were 2.6 mA current, 0.28 V potential, 325 mA/m(2) current density, and 91 mW/m(2) of power density. These results show that the amount of electrical energy produced by microbial fuel cells can be increased 1,000-fold by incorporating electron mediators into graphite electrodes. These results also imply that sewage sludge may contain unique electrophilic microbes that transfer electrons more readily than E. coli and that microbial fuel cells using the new Mn(4+)-graphite anode and Fe(3+)-graphite cathode may have commercial utility for producing low amounts of electrical power needed in remote locations.

Biodegradation, Environmental↗
PubMed2001

Performance of batch membrane reactor: Glycerol-3-phosphate synthesis coupled with adenosine triphosphate regeneration.

Glycerol-3-phosphate (G3P) was synthesized from glycerol using glycerol kinase (GK). This reaction requires adenosine triphosphate (ATP) and was coupled with the ATP regeneration reaction using acetate kinase (AK) in a batch-operated ultrafiltration hollow-fiber reactor. By taking into consideration the dynamic nature of the bioreactor performance under non-steady-state conditions, a model for the performance of a batch membrane reactor for G3P synthesis coupled with ATP regeneration was developed and studied. The simulation results showed good agreement with the experimental results. The simulation studies have provided some insight into the process dynamics of the coupled reactions in the reactor system studied. For the reactor operational model used, in which the enzymes are retained in the shell side and the substrates are also initially placed in the shell side, it was found that the substrate concentration in the lumen side increased to a level higher than that in the shell side, and a backdiffusion occurred from the lumen side to the shell side during reactor operation. The ratio of the reaction rate to diffusion rate goes through a sharp peak during the time that the direction of diffusion is reversed. For another reactor operational model, in which the substrates were initially placed in the lumen side and enzymes were retained in the shell side, it was found that the rate-controlling step between the reaction and diffusion was switched during the reactor operation. Initially, the reaction rate increased while the diffusion rate was high and the substrate concentrations increased in the shell side. The ratio of reaction rate to diffusion rate increased to a maximum and remained at a constant level as the diffusion rate decreased to a low level due to the nonlinear characteristics of mass transfer process. This study provides information that is useful for optimization of batch membrane enzyme reactor operation and for a fed-batch-type process with an intermittent feeding strategy for efficient use of substrates.

Acetate Kinase↗
PubMed2006

Nitrilotriacetic acid degradation under microbial fuel cell environment.

The removal of nitrilotriacetic acid (NTA) was studied under anaerobic conditions using oligotrophic and copiotrophic microbial fuel cells (MFCs) as a novel wastewater treatment process. Over 85% of NTA was removed from oligotrophic MFCs enriched and maintained with fuel containing NTA, whilst the value was around 20% in oligotrophic MFCs fed with NTA-free fuel, and in copiotrophic MFCs enriched with NTA containing fuel. The oligotrophic MFCs generated current with concomitant utilization of NTA when served as the sole organic compound, suggesting that NTA is oxidized its suitability as fuel in the MFCs.

Biodegradation, Environmental↗
PubMedDate not supplied

Determinants of fat and fiber consumption in American rural energy workers.

BACKGROUND: The objective of this study was to gain insight into the determinants of dietary fat and fiber consumption in American rural energy workers. Main determinants in this study were knowledge, efficacy expectations, and outcome expectations. The determinants will be ordered in a model, assuming that efficacy and outcome expectations predict intention. METHODS: The study consisted of a cross-sectional survey. The questionnaires on food behavior and the determinants of fat and fiber consumption were administered to the subjects at the same time. Models of determinants of fat and fiber consumption were derived from the correlation and regression analyses. RESULTS: There were 211 questionnaires analyzed. The scales were shown to be valid and reliable. In the models of determinants of fat and fiber consumption the following determinants were generated: gender, education, knowledge, interest, efficacy expectations, outcome expectations, and intention. In this study efficacy expectations were important to determine fat and fiber consumption. CONCLUSIONS: Efficacy expectations can be considered an important variable of an intervention program aiming at the decrease of fat consumption and at the increase of fiber consumption in rural energy workers.

Adult↗
PubMed2007

Ethanol production: energy, economic, and environmental losses.

The prime focus of ethanol production from corn is to replace the imported oil used in American vehicles, without expending more fossil energy in ethanol production than is produced as ethanol energy. In a thorough and up-to-date evaluation of all the fossil energy costs of ethanol production from corn, every step in the production and conversion process must be included. In this study, 14 energy inputs in average U.S. corn production are included. Then, in the fermentation/distillation operation, 9 more identified fossil fuel inputs are included. Some energy and economic credits are given for the by-products, including dried distillers grains (DDG). Based on all the fossil energy inputs, a total of 1.43 kcal fossil energy is expended to produced 1 kcal ethanol. When the energy value of the DDG, based on the feed value of the DDG as compared to that of soybean meal, is considered, the energy cost of ethanol production is reduced slightly, to 1.28 kcal fossil energy input per 1 kcal ethanol produced. Several proethanol investigators have overlooked various energy inputs in U.S. corn production, including farm machinery, processing machinery, and the use of hybrid corn. In other studies, unrealistic, low energy costs were attributed to such inputs as nitrogen fertilizer, insecticides, and herbicides. Controversy continues concerning the energy and economic credits that should be assigned to the by-products. The U.S. Department of Energy reports that 17.0 billion L ethanol was produced in 2005. This represents only less than 1% of total oil use in the U.S. These yields are based on using about 18% of total U.S. corn production and 18% of cornland. Because the production of ethanol requires large inputs of both oil and natural gas in production, the U.S. is importing both oil and natural gas to produce ethanol. Furthermore, the U.S. Government is spending about dollar 3 billion annually to subsidize ethanol production, a subsidy of dollar 0.79/L ethanol produced. With the subsidy, plus the cost of production, the cost of ethanol is calculated to be dollar 1.21/L. The subsidy for a liter of ethanol is 45-times greater than the subsidy per liter of gasoline. The environmental costs associated with producing ethanol are significant but have been ignored by most investigators in terms of energy and economics. The negative environmental impacts on cropland, and freshwater, as well as air pollution and public health, have yet to be carefully assessed. These environmental costs in terms of energy and economics should be calculated and included in future ethanol analyses. General concern has been expressed about taking 18% of U.S. corn, and more in the future, to produce ethanol for burning in automobiles instead of using the corn as food for the many malnourished people in the world. The World Health Organization reports that more than 3.7 billion humans are currently malnourished in the world--the largest number ever in history.

Bioelectric Energy Sources↗