Chemiluminometric method for the determination of glycerol in wine by flow-injection analysis with co-immobilized glycerol dehydrogenase/NADH oxidase

A flow-injection method for the determination of glycerol in wine is described. Glycerol dehydrogenase and NADH oxidase were co-immobilized on poly (vinyl alcohol) beads and incorporated in a flow-injection system. The hydrogen peroxide produced was detected chemiluminometrically via a luminol-hexacyanoferrate (III) reaction. Wine was diluted 1000-fold with water and sample solution (50 microl) was injected into the carrier stream. The calibration graph was linear in the range 3 x 10(-7)-3 x 10(-4) M; the detection limit was 7 x 10(-8) M and the sample throughout was 30 h(-1) without carryover.     

Studies on the electrical double layer

Summary The differential double layer capacity of a dropping mercury electrode in contact with 1 N sodium sulphate solutions containing various concentrationsc of nonionic surface active agents is strongly dependent on the timet which has passed after the mercury drop started to grow. The suppression of the capacity value over the zero polarization range increases witht, the time constant of this slow adsorption process being independent of the frequency of the ac bridge and decreasing from 175 msec forc=2.5×10^–5 M to almost zero forc=10^–3 M. It is supposed that the slow diffusion process is the governing factor in this case. The kinetic capacity peaks, both anodic and cathodic, also increase witht in general, the time constants being of the order of msec. These time constants decrease with decreasing frequencyf. The time constants for the anodic peaks decrease, while those for the cathodic peaks increase, with increasing concentrationc. Under certain conditions anomalous behaviours are observed, e. g. the kinetic peaks decrease with increasingt forc=10^–3 atf=3,900 cps. This can be explained by the decrease witht in the fractional interfacial area newly formed, where the kinetic process can take place. If the adsorption exchange process can not take place at the old part of the total interface, the capacity per unit area of the mercury drop decreases witht.

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Zusammenfassung Die differentielle Doppelschichtkapazität einer Quecksilber-Tropf-Elektrode in Kontakt mit In-Natrium-Sulfatlösung, die verschiedene Konzentrationenc von nichtionischen oberflächenaktiven Substanzen enthält, hängt stark von der Zeitt ab, die vergangen ist, nachdem der Tropfen sein Wachstum begonnen hat. Die Herabdrückung des Kapazitätswertes im Null-Polarisationsbereich wächst mitt. Die Zeitkonstante dieses langsamen Adsorptionsprozesses ist unabhängig von der Frequenz der Wechselstrombrücke und nimmt von 175 msec fürc=2,5 · 10^–5 M auf beinahe Null fürc=10^–3 M ab. Es ist zu vermuten, daß die langsame Diffusion in diesem Fall der maßgebende Faktor ist. Die kinetischen Kapazitätsspitzen, anodisch und kathodisch, wachsen ebenfalls mitt, die Zeitkonstanten liegen in der Größenordnung von msec. Diese Zeitkonstanten nehmen mit sinkender Frequenzf ab. Die Zeitkonstanten für die anodischen Maxima nehmen ab, während jene für die kathodischen Maxima anwachsen, wenn man die Konzentrationc erhöht. Unter bestimmten Bedingungen wird anomales Verhalten beobachtet. Z. B. nehmen die kinetischen Maxima mit wachsender Zeit fürc=10^–3 beif=3900 Hz ab. Das kann durch die Abnahme erklärt werden, mit der der Bruchteil an Grenzfläche neu gebildet wird, während der kinetische Prozeß stattfindet. Wenn der Adsorptions-Austauschprozeß in den älteren Teilen der Gesamtoberfläche nicht mehr stattfinden kann, sinkt die Kapazität pro Flächeneinheit des Quecksilbertropfens mit der Zeitt.

     

THE REGENERATION OF VISUAL PIGMENTS AND THE CHANGE OF ROD HYPERSENSITIVITY AFTER IRRADIATION BY BLEACHING LIGHT IN FROG RETINA

Abstract— The regeneration processes of visual pigments and the dark adaptation processes of rod photoreceptor after irradiation by bleaching light were studied by spectrophotometric, electroretinographic(ERG) methods and the measurement of early receptor potentials (ERPs) in bullfrog retina. After irradiation by bleaching light, rhodopsin in the isolated retina regenerated to an extent depending on the wavelength and intensity of the bleaching light as well as pH. Intense blue light and a weak alkaline environment (pH 7.5–9.5) favoured the regeneration. The regeneration of pigment in the green rods could not be detected in these experiments on the isolated retina. The regeneration of cone pigment was studied by measuring ERPs from both isolated retinas and retinas with pigment epithelium-choroid complex separated from scleras, which are called PEC-retinas. In the PEC-retinas, cone pigment regenerated more rapidly and with better efficiency than in the isolated retinas.
Rod photoreceptors desensitized permanently by bleaching light did not demonstrate hypersensitivity at 0.1 m M [Ca²⁺]_out, which induced hypersensitivity in non-desensitized photoreceptor, but showed the hypersensitivity when the [Ca²⁺]_out, was lowered further by the addition of EGTA.     

Substituent Distribution of Cyanoethyl Cellulose

Estimation of the substitution distribution for cyanoethyl cellulose was carried out by ¹H and ¹³C NMR spectroscopic analyses after the additional acetylation. Based on the complemental function of cyanoethyl and acetyl substituents, the degree of substitution (DS) of cyanoethyl groups could be calculated from the ratios of the ¹H integrated intensities in acetyl methyl ( 1.8–2.1) and cyanoethyl methylene ( 2.6–2.9) protons, and also from the corresponding ratios for acetyl methyl carbon signals ( 19.7–21.3) and cyanoethyl methylene carbon signals ( 17.5–19.0). Good agreement was obtained between the DS values obtained from the NMR spectroscopic analyses and those determined by the conventional nitrogen content method, indicating the validity of the NMR method used. In addition, the NMR method was found to be effective in determining the positional substituent distribution by the quantitative analysis of the three cyan carbon signals ( 118–120).     

Synthesis of dl-coriolin

The total synthesis of dl-coriolin has been achieved in a stereoselective way. The key tricyclic intermediate was synthesized from dicyclopentadiene through a route which involved an S_N2 reaction at a neopentylic position.     

n-type organic field-effect transistors with very high electron mobility based on thiazole oligomers with trifluoromethylphenyl groups

Novel thiazole oligomers and thiazole/thiophene co-oligomers with trifluoromethylphenyl groups were developed as n-type semiconductors for OFETs. They showed excellent n-type performances with high electron mobilities. A 5,5'-bithiazole with trifluoromethylphenyl groups forms a closely packed two-dimensional columnar structure leading to a high performance n-type FET. The electron mobility was enhanced to 1.83 cm2/Vs on the OTS-treated substrate.     

Uniaxial alignment of nematic liquid crystals filling vacant spaces in surface-treated nanofibre nonwoven

ABSTRACT

Nematic liquid crystals (NLCs) absorbed in a nonwoven of surface-treated silica nanofibres (SiO₂-NFs) orient the director along the nonwoven thickness direction if the NLCs prefer homeotropic anchoring onto the fibre surface. The nonwoven has vacant spaces with the dimensions of 0.3 and 0.6 μm in the thickness and cross directions, respectively, bordered with SiO₂-NFs with 93 nm in diameter. The SiO₂-NF surface was treated with a silane-coupling agent to induce the homeotropic anchoring of NLC mesogens onto the surface. The nematic director is arranged radially from the fibres although it is more severely constrained by the proximity between fibre surfaces along the thickness direction. Consequently, the NLCs can align along the nonwoven thickness direction involving ?1/2 wedge disclinations on both sides of the fibres.