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161.
In this paper we argue for the use of iridium oxide (IrO(x)) electrodes as quasi-reference electrodes in microfabricated biosensors and biochips that operate in buffered solutions. The simple microfabrication of these electrodes consists of a one-step electrodeposition of IrO(x) onto a microfabricated platinum (Pt) electrode. The IrO(x) electrode potential was found to vary less than 20 mV over 9 days after stabilization for 1 day in a phosphate-buffered saline (PBS) solution; this behavior of the electrode potential was found to be easily reproduced. Moreover, the electrode potential was found to vary by less than 15 mV in the initial hour of its use; this behavior of the electrode potential was also found to be reproducible. The performance of a microfabricated glucose sensor employing an IrO(x) reference electrode is characterized in this paper in order to evaluate the usefulness of this new IrO(x) electrode as a quasi-reference electrode. The glucose sensor consists of a recessed microfabricated Pt electrode array, an electrodeposited IrO(x) film, an inner layer composed of an electropolymerized poly(m-phenylenediamine)/glucose oxidase (PMPD/GOx) film, and an outer or protective layer composed of Teflon and polyurethane (PU) films. The response of this sensor was found to be equivalent to the response of the same sensor employing a commercial Ag/AgCl reference electrode. These results show that a microfabricated IrO(x) electrode can be used as a quasi-reference electrode in microfabricated biosensors and biochips operating in buffered solutions. 相似文献
162.
Nak Bae Kim Keung-Shik Park Hyung Joo Woo Kil Yong Lee Yoon Yeol Yoon Duk Kyung Kim 《Journal of Radioanalytical and Nuclear Chemistry》1992,160(2):539-548
A radiochemical separation method using an anion exchange resin has been applied to 4N grade tungsten for determining U, Th and 4 other elements. While tungsten remained in the resin, Na, K and As were separated with 0.05M HCl and 1M HF and then U, Th and Cr were eluted with 1M HCl and 1M HF. The separation yield of neptunium (U) was influenced largely by the amount of thorium, but this influence could be neglected as the concentration of the thorium was below 0.5g/ml. The content of these elements were calculated by a single comparator method using monitors, gold and cobalt. The detection limits of U and Th are 4.0 and 1.2 ppb, respectively. 相似文献
163.
In 1961, Karlin and Szegö conjectured : If is an orthogonal polynomial system and is a Sturm sequence, then is essentially (that is, after a linear change of variable) a classical orthogonal polynomial system of Jacobi, Laguerre, or Hermite. Here, we prove that for any orthogonal polynomial system , is always a Sturm sequence. Thus, in particular, the above conjecture by Karlin and Szegö is false.
164.
165.
166.
Dinuclear [(TPyA)FeII(DBQ2-)FeII(TPyA)](BF4)2 possesses extensive pi-pi interactions between the FeII dimers that give rise to a two-dimensional supramolecular sheet structure. The magnetic susceptibility shows a room-temperature spin-crossover behavior; however, thermal hysteresis is not observed. 相似文献
167.
168.
Kim KS Noh SB Katsuda T Ito S Osuka A Kim D 《Chemical communications (Cambridge, England)》2007,(24):2479-2481
Intramolecular charge transfer in 5,15-bis(azulenylethynyl) substituted zinc(ii) porphyrin leads to a significant enhancement of two-photon absorption at near-IR region, which has been investigated by femtosecond Z-scan method. 相似文献
169.
A novel microchip electrophoresis method was developed and applied for sensitive detection and quantitative analysis of endotoxins extracted from Gram-negative bacteria. The method provides a fast and quantitative differentiation of smooth and rough endotoxins based on the solubilization and complexation of the lipopolysaccharides with dodecylsulfate, and then with a fluorescent dye. The migration of the complexes was followed by LIF detection. The novel method is able to replace the SDS-PAGE with the advantage of high speed and better sensitivity, and by avoiding the laborious gel-preparation and silver staining. 相似文献
170.
Yoon Yeol Yoon Chul Soo Kim Dong Yoon Yang Wook Hyun Nahm Soo Young Cho Kil Yong Lee 《Journal of Radioanalytical and Nuclear Chemistry》2008,276(1):187-191
Sediment core samples taken from the Jinheung catchment located in the middle of the Korean Peninsula were used to know environmental
radionuclide distribution. The grain sizes of the sediment cores were found at depth of about 17 cm suggesting that it might
have occurred during a dry period of 1969. The radionuclides, 137Cs, 237Np, 239Pu, 240Pu, 234U, 238U, 228Th, 230Th, 232Th, were analyzed by sector type ICP-MS and gamma-spectrometry. The Cs and Pu distribution changed with the depth, in which
the maximum ranged from 14 to 22 cm. This was due to the high activity of the results of nuclear bomb tests in the air from
1960s and showed different distribution pattern on the soil surface. The average activity ratio of 240Pu/239Pu and 237Np/239Pu was 0.173 and 0.45, respectively. These values were similar to the north hemisphere global fallout ratio of 240Pu/239Pu (0.18) and 237Np/239Pu (0.45). The 237Np/239Pu ratio showed a higher value than the global fallout ratio above 14 cm depth. The U, Th and their daughter radionuclides
kept secular equilibrium in the sediment core because the average activity ratios were nearly 1. 相似文献