New colorimetric detection of glucose by means of electron-accepting indicators: ligand substitution of [Fe(acac)3-n(phen)n]n+ complexes triggered by electron transfer from glucose oxidase

A new colorimetric detection technique for glucose, based on electron transfer from glucose oxidase (GODred) to iron(III) acetylacetonate(acac)/phenanthroline(phen) mixed complexes, is developed. When GOD is added to an aqueous mixture that contains tris(acetylacetonato)iron(III) complex (FeIII-(acac)3), 1,10-phenanthroline (phen), and glucose, the color immediately changes from pale yellow to red. The red color originates from formation of tris(1,10-phenanthroline)iron(II) complex ([FeII(phen)3]2+). Differential pulse voltammetry indicates that cationic, mixed-ligand complexes of [Fe(acac)3-n-(phen)n]n+ are formed upon mixing the labile FeIII(acac)3 complex and phenanthroline. The cationic mixed-ligand complexes electrostatically bind to GOD (pI 4.2), and are easily reduced by electron transfer from GODred. This electron transfer is not affected by the presence of oxygen. The reduced complex [FeII(acac)3-n(phen)n](n-1)+ then undergoes rapid ligand exchange to FeII (phen)3. Formation of the colored FeII complex is repressed when the salt concentration in the mixture is increased, or when anionic bathophenanthroline disulfonate (BPS) is employed in place of phenanthroline. The use of labile metal complexes as electron acceptors would be widely applicable to the design of new biochromic detection systems.     

Optical Characteristics of the Retroreflector in Space for the Advanced Earth Observing Satellite

Optical characteristics of the flight unit of the retroreflector in space (RIS) for the Advanced Earth Observing Satellite (ADEOS) were tested with a 60-cm diameter interferometer. The efficiency of the reflection of the RIS on the ADEOS in orbit was simulated based on the measured wavefront for the ground stations at several different latitudes.     

Monolithic Silica Columns for HPLC,Micro‐HPLC,and CEC

Two types of monolithic silica columns derivatized to form an ODS phase, one prepared in a fused silica capillary (SR‐FS) and the other prepared in a mold and clad with an engineering plastic (poly‐ether‐ether‐ketone) (SR‐PEEK), were evaluated. The column efficiency and pressure drop were compared with those of a column packed with 5‐μm ODS‐silica particles and of an ODS‐silica monolith prepared in a mold and wrapped with PTFE tubing (SR‐PTFE). SR‐FS gave a lower pressure drop than a column packed with 5‐μm particles by a factor of 20, and a plate height of 20 μm at a linear velocity below 1 mm/s. SR‐PEEK showed higher flow‐resistance than the other monolithic silica columns, but they still showed a minimum plate height of 8–10 μm and a lower pressure drop than popular commercial columns packed with 5‐μm particles. The evaluation of SR‐FS columns in a CEC mode showed much higher efficiency than in a pressure‐driven mode.     

Radiation clusters and the active control of sound transmission into a symmetric enclosure

Radiation cluster control is proposed for the purpose of attenuating harmonic sound transmission into a symmetric enclosure using error signals derived from structural vibration sensors. The approach falls into a category of middle authority control, which is between LAC (low authority control: structural modal control) and HAC (high authority control: radiation modal control), possessing the benefit of practicality over LAC, while providing high control performance and some flexibility of control gain assignment similar to HAC. The structure of a radiation cluster control system is outlined, showing that it is possible to control a target cluster without affecting the other clusters. A design procedure for the radiation cluster control system is then proposed. Numerical results are also presented.     

Axial structures of biphenyl compounds linked by diethyl ether chains

Two simple biphenyl compounds, I and II, linked by diethyl ether chains have been synthesized. These biphenyl compounds are able to respectively rotate about an internal axis. From X-ray analyses, it was found that the 2,2′-linked biphenyl compound I can transmit the same axial chirality of the biphenyl backbones through the diethyl ether chains. On the other hand, in the 3,3′-linked biphenyl compound II, the opposite axial chirality of the biphenyl backbones is transmitted.     

Selectable one-dimensional or two-dimensional gas chromatography-olfactometry/mass spectrometry with preparative fraction collection for analysis of ultra-trace amounts of odor compounds

A novel selectable one-dimensional ((1)D) or two-dimensional ((2)D) gas chromatography-olfactometry/mass spectrometry with preparative fraction collection (selectable (1)D/(2)D GC-O/MS with PFC) system was developed. The main advantages of this system are the simple and fast selection of (1)D GC-O/MS or (2)D GC-O/MS or (1)D GC-PFC or (2)D GC-PFC operation with a mouse click (without any instrumental set-up change), and total transfer of enriched compounds with thermal desorption (TD) on the same system for identification with (2)D GC-O/MS analysis. Recovery of PFC enrichment with 20 injection cycles of 15 model compounds at 500pg each (e.g. alcohol, aldehyde, ester, lactone, and phenol) was very good with recoveries in the range of 98-116%. The feasibility and benefit of the proposed system was demonstrated with an identification of off-flavor compounds (e.g. 2,4,6-trichloroanisole (TCA), 2-isobutyl-3-methoxypyrazine (IBMP), and geosmin) in spiked wine at odor perception threshold level (5-50ngL(-1)). After parallel stir bar sorptive extraction (SBSE) for 20 aliquots of a sample and subsequent PFC enrichment for the odor-active fractions from the 20 stir bars, three off-flavor compounds were clearly resolved and detected with TD-(2)D GC-O/MS in scan mode. The good efficiency of SBSE-PFC enrichment in the range of 71-78% shows that all analytical steps, e.g. SBSE, TD, (1)D/(2)D GC-O/MS, and PFC, are quantitative and identification of off-flavor compounds at ngL(-1) level in wine is possible.     

Strategic multi-store opening under financial constraint

This paper analyzes strategic store openings in a situation in which firms can open multiple stores depending on the financial constraints of the firm. Specifically, given any upper limit of the number of store openings that two potentially symmetric firms can open, they sequentially determine the number of store openings, including their locations, to maximize their profits. As a result of our analysis in a microeconomic framework, we show that the equilibrium strategy can be wholly classified into only two following opposite strategies according to the level of their financial constraints involved. When firms can afford to invest significant amounts of money in the market, the leader chooses “segmentation strategy,” in which a part of the market can be monopolized by opening a chain of multiple stores and deterring the follower’s entry. In contrast, when the leader has a severe financial constraint so that it can only monopolize less than half of the market, the leader chooses “minimum differentiation strategy,” where firms open each of their stores at exactly the same point as the rival’s. Under this strategy, the leader necessarily captures just half of the market. Furthermore, we show that regardless of potential symmetry between firms, both first and second mover advantages in terms of profit can occur in the equilibrium.     

Adaptive feedforward control of a rectangular panel using a wave filter constructed with point sensors

This paper presents the wave filtering method for a rectangular panel, which is necessary for a feedforward wave control system, and clarifies its validity in the control system. Firstly, a wave solution of a rectangular panel is derived to describe the wave dynamics of the structure. This is followed by the derivation of the wave filtering equations that indicates the structure of the filter. It is found that the proposed wave filter consists of a modal filter, a rearrangement filter and a wave decomposition filter. Then, from the viewpoint of numerical simulations, the characteristics of the wave propagation in a rectangular panel as well as the accuracy of the wave fitter are verified. For the evaluation of the filter accuracy, the condition number is used as a performance index. Finally, an experiment on the adaptive feedforward control system using the wave filter is carried out, demonstrating that the reflected wave absorbing control enables the inactivation of vibration modes.     

Metallation of a cyclic chlorophyll hetero-dyad, and the optical properties of synthetic metallo-dyads

A cyclic chlorophyll hetero-dyad 1-H₂H₂, prepared by double ester linking of two structurally different pyropheophorbide-a moieties through 3-CH₂OCO-13²′ and 17²-COOCH₂-3′, was metallated with zinc and copper to give mono and di-metallated complexes 1-MH₂ or 1-H₂M and 1-MM. The metallation proceeded stepwise and regioselectively, with predominant synthesis of one of the two mono-metallated complexes 1-MH₂ as intermediate. The di-zinc complex produced, 1-ZnZn, was demetallated exclusively via the same mono-zinc complex 1-ZnH₂ as was the major intermediate during metallation. Visible and/or circular dichroism spectra of 1-H₂H₂, 1-MH₂, 1-H₂M, and 1-MM (M = Ni, Cu, or Zn) were measured in organic solvents. Intramolecular interaction of chlorin chromophores is discussed and compared with that of the corresponding monomeric species.     

Preparation of Polymeric Analogs of Tetramethylurea and Their Use as Liquid-Liquid Phase-Transfer Catalysts

Polymeric analogs of tetramethylurea were prepared by free-radical polymerization of N,N,N'-trimethyl-N'-p-vinylbenzylurea and copolym-erization of this monomer with styrene. These polymers are soluble in toluene and have the ability to extract alkali metal ions such as lithium, sodium, and potassium. Moreover, these polymers act as phase-transfer catalysts for typical S _N 2 reactions, although the monomeric analogs tetramethylurea and N,N,N'-trimethyl-N'-benzylurea do not. A plausible mechanism for these catalytic reactions is proposed.