Inertia-preserving secant updates

Corrections to the last two equations of Ref. 1 are given.     

Application of thermospray liquid chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry for the identification of cynomolgus monkey and human metabolites of SK & F 101468, a dopamine D2 receptor agonist

A combination of thermospray liquid chromatography-mass spectrometry (LC-MS) and LC MS MS has allowed the structural elucidation of a number of metabolites of 4-[2-(dipropylamino)ethyl]-1,3-dihydro-2H-indol-2-one (SK & F 101468) in monkey urine. By using LC-MS-MS with the third quadrupole (Q3) set up in multiple ion detection (MID) mode, a number of metabolites were subsequently detected in the human urine and plasma samples despite very low dosing regimes. This was achieved with minimal sample preparation, e.g. for the urine sample centrifugation was the only preparative step, in order to remove particulate matter, prior to analysis. The good signal-to-noise ratio obtained for the human samples, using LC MS MS with Q3 set up for MID, raised the possibility of a LC-MS-MS quantitative assay. As a result, the detection limit of this method for SK&F 101468 when dissolved in methanol was determined to be in the region of 20 pg on column.     

Absorptivity of nitric oxide in the fundamental vibrational band

From observations of the spectral absorbance of mixtures of nitric oxide in nitrogen at room temperature, we derive an integrated absorptivity for the NO fundamental band of 137.3±4.6 cm^-2 atm^-1 at 0°C. The indicated uncertainty is the estimated maximum error.     

Probing buried interfaces with non-linear optical spectroscopy

The importance of buried interfaces in our everyday lives and in current scientific research is highlighted, along with experimental difficulty associated with studying such systems. We present an overview of the application of second harmonic generation and sum-frequency spectroscopy to the study of buried interfaces. Several examples from the current literature are presented, ranging from chemical and biological, to electrical and magnetic interfaces. The importance of this work in the context of ongoing research in these areas is discussed. Finally, we provide a snapshot of the state of the art in non-linear optical spectroscopy by mentioning several new directions that are likely to have a large impact on future research into the physics and chemistry of buried interfaces.     

The laser-induced fluorescence spectrum of chromyl fluoride (chromium dioxidedifluoride) in a seeded molecular beam

We habe obtained part of the laser-induced fluorescence spectrum of chromyl fluoride in a free jet expansion at an instrumental resolution of better than 0.001 cm^?1. This spectrum (together with that of the dispersed fluorescence) allows the identification of the (0,0) band or the absorption spectrum and of several progressions in the lowest bending frequency.     

The thermal degradation of polysiloxanes: Part 6—Products of degradation of poly(tetramethyl-p-silphenylene siloxane) and copolymers with dimethylsiloxane

The volatile products of thermal degradation of poly(tetramethyl-p-silphenylene siloxane) and a series of copolymers with dimethylsiloxane have been separated and identified using principally gas chromatography-mass spectroscopy (GC-MS). The effect of temperature of degradation and copolymer composition on the pattern of products has been demonstrated. As the proportion of dimethylsiloxane structures in the copolymers is increased, the predominantly linear products give way to cyclics.     

Synthesis and characterization of uranium (VI) chloride flourides

Uranium (VI) chloride fluorides were synthesized by the reaction of liquid HCl and solid UF₆ between −80 and −114°C. These dark red compounds are unstable above −40 to −60°C. The simplest formulas derived from compositional analysis are UF₅Cl and UF₄Cl₂.     

The reaction between dissociated fluorine and oxides of uranium

Fluorine at 1–5 torr pressure was dissociated with a microwave discharge and passed over samples of UO₂ or U₃O₈. The only reaction products were UF₆ and O₂. The reaction rates were independent of particle size and sample depth, but depended upon the geometric surface of the sample. Kinetic studies were interpreted to show that F-atoms react immediately upon contact with the surface, and that both F₂-molecules and F-atoms react with the sample. When the ratio, F/F₂, is relatively low, the partial pressure of F-atoms is rate determining. When the ratio, F/F₂, is relatively high the rate of diffusion of total fluorine (F+F₂) to the surface is rate determining.     

Selective extraction of blood plasma exchangeable copper for isotope studies of dietary copper absorption

Measuring mineral absorption by fecal monitoring is labor-intensive and relies on good volunteer compliance. Blood indicators of absorption could be advantageous and we have developed a method for selective extraction-of recently absorbed (exchangeable) copper based on dialysis of plasma with histidine and subsequent copper extraction using Chelex resin. The potential for measuring copper absorption by transient enrichment of exchangeable copper with the stable isotope 65Cu from an ingested tracer, was also investigated. This method was compared with that of the fecal monitoring technique in a human volunteer, who consumed a 6 mg dose of 65Cu with inhibitors of copper absorption. Holmium was used as a non-absorbable rare-earth marker of unabsorbed tracer excretion, allowing estimation of re-secreted 65Cu (44 microg d(-1)), and hence calculation of true tracer absorption, which was only 10.8%. Monitoring plasma tracer kinetics showed potential for estimation of copper absorption without the need for fecal copper analysis.