Coulometric argentometric determination of microamounts of sulphur in iron and steel after reduction to hydrogen sulphide with iron(II) in strong phosphoric acid medium

A coulometric method was developed for the determination of microamounts of sulphur in iron and steel. Hydrogen sulphide is quantitatively evolved by reduction with iron(II) in strong phosphoric acid medium and is titrated with electrolytically generated silver ion from a silver anode. Microamounts of sulphide (2.96–224.3 μg) in sodium sulphide standard solutions could be determined with an error of only a few percent. Sulphur in a potassium sulphate standard solution is quantitatively reduced to hydrogen sulphide and could be separated from the solution by heating and determined accurately. Trace amounts of sulphur (7–100 μg g^?1) in iron and steels could be determined with a standard deviation of 0.7–2.1 μg g^?1.     

Simultaneous operation of plural separation modes in capillary electrophoresis with a chemiluminescence detector possessing a micro-space area for reaction/detection

Analysis of alpha-amino acids, proteins, and phenolic compounds was simultaneously performed using three capillaries in capillary electrophoresis with chemiluminescence detection, taking advantage of the micro-space area for reaction/detection at the tip of the capillary. The three capillaries included usual, polymer-containing, and sodium docley sulfate (SDS)-containing migration buffers for separation. The eluted samples from the capillaries, which were inserted into the chemiluminescence detection cell, were mixed with chemiluminescence reagent at the tips of the capillaries to generate visible light. The specific micro-space area for reaction/detection at the tips of the capillaries enabled the simultaneous operation of the three separation modes in the present system.     

Synthesis of new hydrolyzable polyurethanes from L‐gulonic acid‐derived diols and diisocyanates

New polyurethanes with lactone groups in the pendants and main chains were synthesized by the polyaddition of two kinds of L ‐gulonolactone‐derived diols (2,3‐O‐isopropylidene‐L ‐gulono‐1,4‐lactone and 5,6‐O‐isopropylidene‐L ‐gulono‐1,4‐lactone) with hexamethylene diisocyanate and methyl (S)‐2,6‐diisocyanatohexanoate and by the subsequent deprotection of isopropylidene groups. They were hydrolyzed more quickly than the polyurethane derived from methyl β‐D ‐glucofuranosidurono‐6,3‐lactone in a phosphate buffer solution, the pH value of which was 8.0, at 27 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4158–4166, 2002     

Studies on cardiotonic agents. I. Synthesis of some quinazoline derivatives

A series of quinazoline derivatives with various 4-heterocyclylpiperidino groups at the 4-position was synthesized and tested for cardiotonic activity in anesthetized dogs. Among them, several 6,7-dimethoxyquinazoline derivatives showed potent cardiotonic activity.     

Studies on cardiotonic agents. II. Synthesis of novel phthalazine and 1,2,3-benzotriazine derivatives

A series of phthalazine and 1,2,3-benzotriazine derivatives which have heterocyclylpiperidino groups was synthesized and tested for cardiotonic activity in anesthetized dogs. Several 6,7-dimethoxyphthalazine derivatives showed relatively potent cardiotonic activity comparable to that of amrinone.     

High-resolution submicron patterning of self-assembled monolayers using a molecular fluorine laser at 157 nm

Using a molecular fluorine laser at 157 nm wavelength, submicron patterning of organosilane self-assembled monolayers (SAMs) is demonstrated utilizing mask-contact photolithography. An organosilane, namely, octadecyltrimethoxysilane [ODS, CH(3)(CH(2))(17)Si(OCH(3))(3)], SAM is chemisorbed onto Si substrates covered with a 2 nm thick oxide layer and subsequently patterned using the laser. The optical path of the laser beam and the photomask-sample space are evacuated and then backfilled and purged with nitrogen during laser firing. The resulting pattern is investigated using various measurement techniques. The scanning probe microscopy images show that patterns are transferred to the SAM-covered Si substrates and that 500 nm features are successfully photoprinted in this way.     

Fragmentation study of peptides using Fourier transform ion cyclotron resonance with infrared multiphoton dissociation: experiment and simulation

In this study, the fragmentation of gas-phase protonated Angiotensin II is investigated using electrospray ionization (ESI), Fourier-transform ion cyclotron resonance (FT-ICR), and mass spectrometry (MS) with a laser cleavage infrared multiphoton dissociation (IRMPD) technique. The experimental results show that the spectra peaks for the photoproducts are y2/b6- and y7-type ions, corresponding to the cleavage of His-Pro and Asp-Arg in the parent amino acid sequence. The fragmentation of the peptide under collision-free vacuum conditions is modeled using molecular dynamics simulations (MD). The binding energy for the peptide bonds (C'-N bond) of Angiotensin II is estimated from ab initio calculations. The calculations are directed at predicting experimental measurements of the product ions from the photodissociation of the peptide. The product distributions simulated by the MD dissociation trajectories include predominantly y7/b1 and y2/b6 pair ions.     

Thermodynamics of Solvation of 18-Crown-6 and Its Alkali-Metal Complexes in Various Solvents

Heats of solution of 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6) in acetonitrile, 1,2-dichloroethane, N,N-dimethylformamide, dimethyl sulfoxide, nitromethane, propylene carbonate, pyridine and water were measured at 25 °C and the enthalpies of the transfer of 18-crown-6 from waterto the aprotic solvents were derived. The thermodynamic quantities, G₁°, H₁° and T S₁°, for the formation of the[M(18-crown-6)]⁺ (M⁺ = Na⁺, K⁺, Rb⁺, Cs⁺, NH₄ ⁺) complexeswere determined by titration calorimetry in dimethyl sulfoxide containing0.1 mol dm^-3 (C₂H₅)₄NClO₄ as a constant ionic medium at 25 °C. These thermodynamic quantities suggest that the complexationof 18-crown-6 with the alkali-metal ions mainly reflects the different solvationof 18-crown-6 and also the different degree of solvent structure.     

Monolithic octadecylsilyl-silica gel column for the high-speed ion chromatographic determination of acidity

A monolithic ODS-silica gel column modified by saturating it with lithium dodecylsulfate (Li-DS) was used to demonstrate the high-speed separation of H+ from other mono- and divalent cations, such as Na+, NH4+, K+, Mg2+ and Ca2+ using ion chromatography (IC). Using a 5 mM EDTA-2K solution containing 0.10 mM Li-DS (pH 4.80) as eluent, H+ was eluted with a sharp and symmetrical peak within 1.0 min before other cations at a flow-rate of 1.5 ml min(-1). The rapid elution of H+ and its conductimetric detection could be attributed to the presence of EDTA (HY2-), which can convert H+ ions as anions. i.e. H(+) + H2Y(2-) --> H3Y(-). The acidity of rainwater and deionized water samples was determined using this IC system with satisfactory results.     

Determination of monovalent inorganic anions in high-ionic-strength samples by electrostatic ion chromatography with suppressed conductometric detection

A new ion chromatographic (IC) system has been established by using micelles of 3-(N,N-dimethylmyristylammonio)propanesulfonate (Zwittergent 3-14) loaded onto a reversed-phase packed column as the separation column with an electronic rotary switching valve packed-bed suppressor for conductometric detection of inorganic anions. An aqueous H3BO3-Na2B4O7 solution has been demonstrated to be the most desirable eluent for this IC system. The relationship between retention time and the concentration of the borate eluent was determined for a series of model anionic analytes and this relationship was found to be opposite to that exhibited in a conventional anion-exchange IC system. The rapid elution and complete separation of monovalent inorganic anions were obtained by initially using a high-concentration borate solution as the eluent for a short-period, and then switching to a lower-concentration borate eluent to complete the separation. Detection limits for nitrite, bromide, nitrate, and chlorate were 0.85, 0.88, 0.95 and 4.8 microM, respectively, when a 7.0 mM Na2B4O7 eluent was used. Moreover, the ability to directly detect these monovalent anions in samples containing high concentrations of sulfate and/or chloride ions provided a major advantage of this approach.