Strategic Trade and Industrial Policies with International R&D Spillovers

本稿では,企業の研究開発(R&D)の成果が国境を越えてスピルオーバーする国際貿易モデルにおいて,輸出補助金ならびにR&D補助金の効果を分析する.国際寡占企業間のR&D投資競争がクールノー型数量競争ないしベルトラン型価格競争に先んじて行なわれるという仮定のもとで,輸出国の貿易政策と産業政策の最適な組合せを導出する.最適な輸出補助金とR&D補助金の符号は製品間の代替性,R&Dスピルオーバーの程度,そしてR&D投資の効率性をそれぞれ表すパラメーターに依存して変化することが示される.さらに,輸出国にとって利用可能な政策手段が1つしかない状況下での輸出補助金あるいはR&D補助金の最適性を検討する

Coulometric determination of the antioxidant capacity of tea extracts using electrogenerated bromine

A coulometric procedure based on the reaction between aqueous extracts of tea with electrogenerated bromine compounds was proposed for the rapid estimation of the antioxidant capacity of different kinds of tea. The antioxidant properties of tea with respect to bromine are mainly due to naturally occurring flavonoids, tannins, and some vitamins. Photometric and coulometric data for black teas exhibit good correlation. © 2001 MAIK "Nauka/Interperiodica"

Polyquercetin/MWNT-modified Electrode for the Determination of Natural Phenolic Antioxidants

© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Novel highly sensitive voltammetric method for the gallic acid, catechin and epigallocatechin gallate (EGCG) quantification has been developed using glassy carbon electrode modified with multi-walled carbon nanotubes and polyquercetin (polyquercetin/MWNT/GCE). The effect of electropolymerization parameters (number of cycles, monomer concentration and polarization window) on the electrode characteristics has been evaluated. The electrode surface has been characterized with SEM, CV and EIS. The linear dynamic ranges of 0.50–10 and 10–750 μM for gallic acid, 0.10–10 and 10.0–250 μM for catechin and 0.050–10 and 10–100 μM for EGCG have been obtained in differential pulse mode with the detection limits of 0.10, 0.024 and 0.014 μM, respectively. The approach has been successfully applied for the tea antioxidant capacity evaluation (AOC). The positive correlations with antioxidant activity towards DPPH • and total phenolics (r=0.7845 and 0.7658 at r crit =0.4227, n=22) have been obtained

Determination of copper and cadmium by atomic absorption spectrometry with electrochemical and sorption preconcentration

A method is proposed for the determination of copper and cadmium by atomic absorption spectrometry in a propane-butane-air flame with electrochemical and sorption preconcentration. Electrochemical preconcentration was performed on metal (tantalum, titanium, molybdenum, and platinum), glassy-carbon, and spectrographic graphite electrodes. Sorption preconcentration was performed on filter paper with immobilized dithizone, 8-hydroxyquinoline, and rubeanic acid. It is demonstrated that copper and cadmium can be determined in water within the concentration range 1-10 μg/L

Chronocoulometry of wine on multi-walled carbon nanotube modified electrode: Antioxidant capacity assay

© 2015 Elsevier Ltd. All rights reserved. Phenolic antioxidants of wine were electrochemically oxidized on multi-walled carbon nanotubes modified glassy carbon electrode (MWNT/GCE) in phosphate buffer solution. Three oxidation peaks were observed at 0.39, 0.61 and 0.83 V for red dry wine and 0.39, 0.80 and 1.18 V for white dry wine, respectively, using differential pulse voltammetry at pH 4.0. The oxidation potentials for individual phenolic antioxidants confirmed the integral nature of the analytical signals for the wines examined. A one-step chronocoulometric method at 0.83 and 1.18 V for red and white wines, respectively, has been developed for the evaluation of wine antioxidant capacity (AOC). The AOC is expressed in gallic acid equivalents per 1 L of wine. The AOC of white wine was significantly less than red wine (386 ± 112 vs. 1224 ± 184, p < 0.0001), as might be expected. Positive correlations were observed between gallic acid equivalent AOC of wine and total antioxidant capacity, based on coulometric titration with electrogenerated bromine (r = 0.8957 at n = 5 and r = 0.8986 at n = 4 for red and white wines, respectively)

Analytical possibilities of amperometric choline esterase biosensors in continuous-flow analysis

A model set-up of a simple and convenient continuous-flow analyzer (enzyme reactor) that includes an amperometric choline esterase biosensor for the determination of potential contaminants of the environment is developed. Various modifications of the biosensors developed are used for determination of toxicants in a flow within the concentration range from 1 × 10-3 to n × 10-13 M over 16-36 h. ©1996 Plenum Publishing Corporation

Voltammetric determination of α-tocopherol in the presence of surfactants

As established, α-tocopherol is electrochemically active on glassy carbon electrode in the available range of anodic potentials in acetonitrile and its aqueous mixtures. However, an increase in the water percentage up to 50% and beyond leads to a substantial decrease and then the total disappearance of the analytical signal. A scheme of electrode reaction responsible for the signal formation is proposed. The effect of surfactants on the oxidation of α-tocopherol in aqueous acetonitrile is estimated. As found, surfactants (N-dodecylpyridinium bromide, Triton X-100 and N-cetylpyridinium bromide) enhance the current of α-tocopherol oxidation. The surfactants reduce the detection limit and extend the analytical range. Analytical methods for the voltammetric quantification of α-tocopherol in drugs in the presence of surfactants are elaborated and may be recommended for the control of pharmaceuticals. © 2012 Pleiades Publishing, Ltd

Metal ions as enzyme effectors

The role of metal ions as enzyme effectors is considered. Data on inhibitory and activating effects of metal ions are summarised. The dual character of action of the effectors depending on their concentration and the nature of the enzyme is highlighted. The analytical applications of these effects are discussed. © 1998 Russian Academy of Sciences and Turpion Ltd

Metal ions as effectors of enzymes

Effects of metal ions as modulators of enzymes are considered. Data on inhibition and activation by metal ions are reviewed. Dual action of modulators depending on enzyme nature and effector concentration are noted. Analytical application of metal ions effects is discussed

An enzyme amperometric sensor for toxicant determination

An enzyme sensor with amperometric recording of the analytic signal for determination of a number of cholinesterase (ChE) inhibitors (P-, Cl-containing pesticides, heavy metals) has been developed. It consists of a mercury film-covered silver electrode and ChE immobilized in the nitrocellulose film in the presence of glutaraldehyde. It is shown that the enzyme electrode can be used as a component of an enzyme reactor for the determination of ChE inhibitors and activators under flow conditions. © 1991