Determination of midodrine in human plasma by high-performance liquid chromatography with fluorescence detection.

A simple and sensitive fluorometric high-performance liquid chromatographic method was developed for the determination of midodrine in human plasma. After liquid-liquid extraction from plasma, the drug and 2-phenylglycinol (internal standard) were convened into the corresponding fluorescent derivatives by reaction with 3,4-dihydro-6,7-dimethoxy-4-methyl-3-oxoquinoxaline-2-carbonyl chloride, a fluorescence derivatization reagent for amines. The derivatives were separated within 30 min on a reversed-phase column using isocratic elution with acetonitrile-methanol-water (10:30:60, v/v) and were detected spectrofluorometrically at 485 nm with excitation at 400 nm. The detection limit for midodrine was 0.3 pmol (76 pg) per mL plasma at a signal-to-noise ratio of 3.     

Online photocatalytic device for highly selective pre-column fluorescence derivatization of 5-hydroxyindoles with benzylamine

A fluorimetric liquid chromatographic method for the determination of 5-hydroxyindoles based on the benzylamine derivatization process mediated through an online photocatalytic oxidation has been developed. In this study, we used a photocatalytic column comprising tefzel tubing packed with TiO₂-coated glass beads, as a pre-column derivatization reactor. The fluorescence derivatization of 5-hydroxyindoles using benzylamine proceeded during their passage through the reaction column under near-UV irradiation. The 5-hydroxyindole derivatives were separated continuously on a reversed-phase liquid chromatography within 50 min, using 100 mM acetate buffer (pH 4.6)-acetonitrile (72:28, v/v; isocratic elution) containing 3 mM sodium octanesulfonate; the samples were detected fluorimetrically at 465 nm upon excitation at 350 nm. The detection limits (signal-to-noise ratio = 3) of the 5-hydroxyindoles were in the range from 160 to 360 fmol per 5 μL injection. We have applied this method, which requires minimal sample pre-treatment, to the determination of 5-hydroxyindole-3-acetic acid in human urine.     

Growth of single-layer carbon tubes assisted with iron-group metal catalysts in carbon arc

Single-layer (SL) carbon tubes were produced by arc evaporation of graphite rods containing iron-group metals (Fe, Co, Ni, Fe/Co, Co/Ni, Fe/Ni) under He and Ar gas. Transmission electron microscopy (TEM) revealed that these elemental and binary metals, excluding Fe which need a special atmosphere (a mixture of Ar and CH₄), showed catalytic activity producing SL tubes under pure inactive gases. Fe/Ni alloy was the most effectual catalysts for producing SL tubes. The highest abundance of SL tubes in raw soot was estimated to be ～ 10% from TEM observation. Smoke particles directly caught on TEM grids near an evaporation source during arcburning were also investigated, and it was suggested that small metal particles were first formed in the gas phase and then SL tubes grew from them.     

Field evaporation of silicon surfaces

Quantitative measurements on field evaporation of Si(111) surfaces in hydrogen imaging gas have been carried out by field ion microscopy. The field evaporation rate is found to increase exponentially with increase of the reciprocal of tip temperature in the range 80–103 K. The evaporation field strength increases with increase of tip temperature in the investigated range, 80–300 K. Within the applied pressure range, 5× 10^?6 to 2 × 10^?4 Torr of hydrogen gas, the evaporation rate linearly increases with the gas pressure. Similar effects of temperature and gas pressure on field evaporation of Si(111) surfaces have been observed also in silane imaging gas. A model, based on a field-induced formation of surface hydrides as a rate-determining step, is proposed, which accounts for all the experimental results of the field evaporation process.     

Sinusoidal Phase-Modulating Superluminescent Diode Interferometer with Fabry-Perot Etalone for Step-Profile Measurement

In this paper we use a superluminescent diode (SLD) as the light source of an interferometer and extract a narrow spectrum from a wide spectrum of the SLD with a Fabry-Perot Etalone (FPE). By varying sinusoidally the distance between the two mirrors of FPE, the central wavelength of the narrow spectrum is scanned sinusoidally. The distance between the mirrors is exactly set by a feedback control system, and sinusoidal phase-modulated SLD light that has a large scanning width of about 10 nm can be obtained with high stability and spatial uniformity. The phase of the interference signal has two different components. One is amplitude Z_b of sinusoidal phase modulation, which is proportional to the optical path difference (OPD) and the scanning width. The other is conventional phase α, which provides a fractional value of the OPD in the range of the wavelength. By combining the two values of the OPD obtained from Z_b and α, an exact OPD larger than the wavelength can be measure with ment accuracy in α. Characteristics of the interferometer are made clearly through step-profile measurements.     

Ultra-narrow interval angular control signal for holographic data storage system

Optical Review - A precise and fast method for controlling the reference-beam angle of an angular-multiplexed holographic data storage system (HDSS)—to achieve larger capacity and faster...     

White light emission of Mn-doped SnO-ZnO-P2O5 glass containing no rare earth cation

The authors have demonstrated white light emission of rare earth (RE)-free Mn-doped SnO-ZnO-P(2)O(5) glass. The RE-free glass shows white light emission with a high value of quantum efficiency (QE) comparable to conventional crystalline phosphor. It is notable that the high QE value is attained for RE-free transparent glass, and the broad emission can be continuously tuned by both the amount of activator and the composition of the glass. Since this glass possesses low-melting property, we emphasize that the glass phosphor will lead to the development of a novel inorganic white-light-emitting device in combination with a solid state UV light-emitting source.     

Adsorption and structure of methyl mercaptoacetate on Cu(1 1 1) surface by XPS and NEXAFS spectroscopy

Methyl mercaptoacetate (MA) on Cu(1 1 1) surface was investigated using synchrotron radiation-based X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. MA adsorbs on the surface via thiolate formation and weak interaction of the carbonyl group with the surface. Two different adsorption states previously reported for methanethiolate and ethanethiolate were confirmed, besides atomic sulfur. NEXAFS measurements support gauche-type conformation of MA whose skeleton lies on the surface.     

Synthetic Strategies of Carbon Nanobelts and Related Belt-Shaped Polycyclic Aromatic Hydrocarbons

The development of carbon nanobelts and related belt-shaped polycyclic aromatic hydrocarbons has gained momentum in recent years. This Minireview focuses on the synthetic strategies used in constructing these aesthetically appealing molecular nanocarbons. Examples of carbon nanobelts and related belt-shaped polycyclic aromatic hydrocarbons reported in recent years as well as some representative synthetic attempts in earlier times are discussed.     

Diversity-oriented synthesis of tamoxifen-type tetrasubstituted olefins

A general synthetic scheme for tamoxifen-type tetrasubstituted olefins based on the novel Cu-catalyzed carbomagnesation across alkynyl(2-pyridyl)silane has been developed. A wide array of electronically and structurally diverse tetrasubstituted olefins can be prepared in a regiocontrolled, stereocontrolled, and diversity-oriented manner. Noteworthy features are that (i) the three aryl groups, which are believed to be important (essential) for anti-estrogenic activity, can be varied at will because they all stem from readily available aryl iodides, and (ii) any stereo- and regioisomers can, in principle, be prepared by simply changing the applying order of aryl iodides into the sequence.