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Takada N.,Japan National Institute of Advanced Industrial Science and Technology | Ishii H.,Japan Applied Technology Inc.
Chemical Physics Letters | Year: 2014

The thermoluminescence (TL) exhibited by crystalline tris(2-phenylpyridine) iridium (Ir(ppy)3) microrods was investigated over temperatures of 29-160 C using a multichannel Fourier transform spectrometer. The glow curves and TL spectra were analyzed to elucidate the origins of the emission. Four peaks were observed at different temperatures in the glow curves. Furthermore, by analyzing the TL spectra, we found that various types of charge-carrier trap sites exist in Ir(ppy)3; these sites become active or remain inactive, depending on the presence of oxygen or light or both. Thus, charge-carrier trapping within crystalline Ir(ppy)3 depends on the environment to which the sample has been exposed. © 2014 Elsevier B.V. All rights reserved. Source


Sago T.,Japan National Institute of Advanced Industrial Science and Technology | Ishii H.,Japan Applied Technology Inc. | Hagihara H.,Japan National Institute of Advanced Industrial Science and Technology | Takada N.,Japan National Institute of Advanced Industrial Science and Technology | Suda H.,Japan National Institute of Advanced Industrial Science and Technology
Chemical Physics Letters | Year: 2013

We studied chemiluminescence spectroscopy to develop an evaluation method for organic material degradation. The thermal oxidation of oleic acid as a monounsaturated fatty acid was investigated using chemiluminescence measurements. The obtained spectra indicated that the luminescence consisted of several peaks, including peaks for singlet oxygen and excited carbonyls. A detailed analysis of the nuclear magnetic resonance and infrared absorption spectra allowed us to determine the probable structures of the oxidative products. The relationship between the spectrum and the analyzed structure implied that the wavelength of the carbonyl group emission peak shifted as a result of the structure. © 2013 Elsevier B.V. All rights reserved. Source


Millington K.R.,CSIRO | Ishii H.,Japan Applied Technology Inc. | Maurdev G.,CSIRO
Amino Acids | Year: 2010

Chemiluminescence (CL) with maximum emission in the range 550-650 nm is observed when proteins and certain amino acids are heated in air, and CL intensity is significantly reduced in nitrogen. Of the 20 common amino acids, lysine (Lys) has the highest thermal CL intensity by a factor of ∼ 30 over arginine, threonine and asparagine. This finding differs from previous studies on amino acids and proteins oxidised using free radical initiators or singlet oxygen, where tryptophan was the dominant factor for CL emission. CL from heating solid Lys in air is accompanied by browning and the generation of fluorescent products which are characteristic of advanced glycosylation end products (AGEs) in thermally treated milk proteins. During thermal oxidation, Lys may react with its own carbonyl oxidation products to form fluorescent compounds similar to AGEs via the formation of Schiff bases. The mechanism of thermal oxidation of proteins may be similar to polyamide polymers, where reaction of free primary amino groups with carbonyls to form Schiff bases plays a key role. Source


Shimomura T.,Japan Applied Technology Inc. | Sumiya T.,Japan Applied Technology Inc. | Ono M.,Japan Applied Technology Inc. | Ito T.,Japan National Institute of Advanced Industrial Science and Technology | Hanaoka T.-A.,Japan National Institute of Advanced Industrial Science and Technology
Analytica Chimica Acta | Year: 2012

A novel amperometric biosensor for the measurement of l-lactate has been developed. The device comprises a screen-printed carbon electrode containing cobalt phthalocyanine (CoPC-SPCE), coated with lactate oxidase (LOD) that is immobilized in mesoporous silica (FSM8.0) using a polymer matrix of denatured polyvinyl alcohol; a Nafion layer on the electrode surface acts as a barrier to interferents. The sampling unit attached to the SPCE requires only a small sample volume of 100 μL for each measurement. The measurement of l-lactate is based on the signal produced by hydrogen peroxide, the product of the enzymatic reaction. The behavior of the biosensor, LOD-FSM8.0/Naf/CoPC-SPCE, was examined in terms of pH, applied potential, sensitivity and operational range, selectivity, and storage stability. The sensor showed an optimum response at a pH of 7.4 and an applied potential of +450. mV. The determination range and the response time for l-lactate were 18.3 μM to 1.5. mM and approximately 90. s, respectively. In addition, the sensor exhibited high selectivity for l-lactate and was quite stable in storage, showing no noticeable change in its initial response after being stored for over 9 months. These results indicate that our method provides a simple, cost-effective, high-performance biosensor for l-lactate. © 2011 Elsevier B.V. Source


Shimomura T.,Japan Applied Technology Inc. | Sumiya T.,Japan Applied Technology Inc. | Ono M.,Japan Applied Technology Inc. | Ito T.,Japan National Institute of Advanced Industrial Science and Technology | Hanaoka T.-A.,Japan National Institute of Advanced Industrial Science and Technology
Analytical and Bioanalytical Chemistry | Year: 2013

A disposable amperometric biosensor for ketone 3-β-hydroxybutyrate (3HB) has been developed successfully. The sensor is based on a screen-printed carbon electrode containing Meldola's Blue (MB) and sensing components containing nicotinamide adenine dinucleotide (NAD+) and 3-β-hydroxybutyrate dehydrogenase (3HBDH) immobilized in mesoporous silica (FSM8.0) using an aqueous photo-cross-linkable polymer matrix of polyvinyl alcohol (O-391), and it requires only a small sample volume of 10 μL for the measurement. The behavior of a resulting biosensor, i.e., 3HBDH-FSM8.0/NAD +/MB-SPCE, was examined in terms of NAD+ concentration for construction, pH, applied potential, operational range, selectivity, and storage stability. The sensor showed an optimum response at a pH of 7.6 and at an applied potential of -50 mV. The determination range and the response time for 3HB were from 30 μM to 8 mM and approximately 30 s, respectively. In addition, the sensor was quite stable and maintained >90 % of its initial response after being stored for over 6 months. This result implies that our method provides a novel biosensor for ketone 3-β-hydroxybutyrate which is easy-to-use, cost-effective, and has good reproducibility, which are vital for commercial purposes. [Figure not available: see fulltext.] © 2012 Springer-Verlag Berlin Heidelberg. Source

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