Search Results - (Author, Cooperation:B. K. Ahn)

2013-10-05

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

1365-2133

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] One approach to the artificial kidney could be the electrochemical degradation of the nitrogenous wastes and their conversion to non-toxic products, capable of excretion by other means. For example, if nitrogen containing wastes were converted to water, carbon dioxide and nitrogen, the water would ...

Electronic Resource

1741-0444

MiniaturepH glass electrode f.e.t. amplitier

Springer Online Journal Archives 1860-2000

Biology

Chemistry and Pharmacology

Medicine

Sommaire Une électrode miniature depH en verre destinée à des applications cliniques et biomédicales éventuelles a été construite puis évaluée dans des solutions tamponspH de référence, à la température de 36°C. Un amplificateur à transistor à effet de champ (f.e.t.) a été intégré au système et son efficacité a été étudiée. La f.é.m. moyenne du système de l'électrode mise au point était de 0·87±0·11, et une longueur minimum de 7·0 mm était nécessaire pour une réponsepH satisfaisante. La dépendance de température de l'électrode était de −1·51 mV/oK à unpH de 7. L'évaluation de la stabilité de l'électrode présentait un glissement de 1% pendant une durée de fonctionnement de 7 h. Les effets d'hystérésis température etpH présentaient des écarts de 0·5% et de 1·0%, respectivement. Le temps de réponse se situait dans les limites de 4 s pour une réponse de 99%. Ces caractéristiques d'électrode que nous débattons ont également été examinées dans le plasma sanguin.

Zusammenfassung Es wurde eine Miniatur-pH-Glaselektrode für eine eventuelle klinische und biologischmedizinische Anwendung gebaut und in bezung aufpH-Pufferlösungen bei 36°C beurteilt. Ein Feldeffekttransistor-Verstärker (f.e.t.) wurde in das System eingebaut, dessen Wirksamkeit untersucht wurde. Die effektive durchschnittliche Leistungsfähigkeit der entwickelten Elektrode betrug 0·87±0·11. Für gutepH-Reaktionen war eine Mindestlänge von y mm erforderlich. Die Temperaturabhängigkeit der Elektrode betrug—1·51 mV/oK bei einempH-Wert von 7. Bei der Bewertung der Elektrodenstabilität zeigte sich eine Abweichung von 1% bei einer Einsatzdauer von 7 Stunden.pH- und Temperatur-Hystereseeffekte zeigten Abweichungen von 0·5 bzw 1·0%. Bei 99% der Reaktionen lag die Reaktionszeit innerhalb von 4 Sekunden. Diese Elektrodeneigenschaften wurden ferner im Blutplasma untersucht und besprochen.

Abstract A miniaturepH glass electrode for possible clinical and biomedical applications was constructed and evaluated in referencepH buffer solutions at 36°C. A field-effect-transistor (f.e.t.) amplifier was integrated into the system, and its effectiveness was investigated. The average e.m.f. efficiency of the developed electrode was 0·87±0·11V, and a minimum length of 7 mm was required for a goodpH response. Temperature dependence of the electrode was −1·51 mV/oK at apH of 7. Evaluation of the stability of the electrode showed a 1% drift over a 7 h operational time. ThepH and temperature hysteresis effects showed 0·5% and 1·0% deviations, respectively. The response time was within 4 s for 99% response. These electrode characteristics were also investigated in blood plasma and discussed.

Electronic Resource

0021-9304

Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Medicine

Technology

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°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 kΩ 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.

4 Ill.

Electronic Resource