19th Annual Conference on Analytical Chemistry

Program and abstracts from the 19th annual meeting of the Conference on Analytical Chemistry, co-sponsored by the Rocky Mountain Section of the Society for Applied Spectroscopy and the Rocky Mountain Chromatography Discussion Group. Held in Denver, Colorado, August 1-3, 1977

Resident research associateships. Postdoctoral and senior research awards: Opportunities for research at the Jet Propulsion Laboratory

Opportunities for research as part of NASA-sponsored programs at the JPL cover: Earth and space sciences; systems; telecommunications science and engineering; control and energy conversion; applied mechanics; information systems; and observational systems. General information on applying for an award for tenure as a guest investigator, conditions, of the award, and details of the application procedure are provided

Analysis and applications of FTIR systems

Fourier Transform Infrared Spectroscopy (FTIR) is a dynamical instrumental technique used in industry for measuring high quality infrared spectra. Over the last 25 years, the increased demand for having an efficient real-time quantitative measurement technique has led to extensive research and development in the field of FTIR Spectroscopy. Through the use of FTIR, sensitivity has increased, size of the smallest sample that can be analyzed has been reduced, and the number of new applications has exploded. In this thesis, an attempt is made to study the principles, theory, instrumentation and applications of FTIR Spectrometry. We survey the working of spectrometer, computation techniques, methodology, spectral manipulations, hardware, trading rules and the applications

21st Rocky Mountain Conference on Analytical Chemistry

Abstracts and meeting program from the 21st annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-sponsored by the Rocky Mountain Section of the Society for Applied Spectroscopy and the Rocky Mountain Chromatography Discussion Group. Held in Denver, Colorado, July 30 - August 1, 1979

Measurement techniques and instruments suitable for life-prediction testing of photovoltaic arrays

Array failure modes, relevant materials property changes, and primary degradation mechanisms are discussed as a prerequisite to identifying suitable measurement techniques and instruments. Candidate techniques and instruments are identified on the basis of extensive reviews of published and unpublished information. These methods are organized in six measurement categories - chemical, electrical, optical, thermal, mechanical, and other physicals. Using specified evaluation criteria, the most promising techniques and instruments for use in life prediction tests of arrays were selected

Organosiloxane working fluids for the liquid droplet radiator

Siloxane-based working fluids for advanced space radiators requiring direct fluid exposure to the space environment are evaluated. Isolation of five candidate fluids by vacuum distillation from existing siloxane polymers is discussed. The five fluids recovered include a polydimethylsiloxane, three phenyl-containing siloxanes, and a methylhexylsiloxane. Vapor pressures and viscosities for the five fluids are reported over the temperature range of 250 to 400 K. Use of thermal-gravimetric analysis to reliably estimate vapor pressures of 10 to the -8 power Pascals is described. Polydimethylsiloxane (PDMS) and polymethylphenylsiloxane (PMPS) are selected from the five candidate fluids based on favorable vapor pressure and viscosity, as well as perceived stability in low-Earth orbit environments. Characterization of these fluids by infrared spectroscopy, Si-29 NMR, gel-permeation chromatography, and liquid chromatography is presented. Both fluids consist of narrow molecular weight distributions, with average molecular weights of about 2500 for PDMS and 1300 for PMPS

Topographical Studies of the Nicotinic Acetylcholine Receptor

All four subunits of the nicotinic acetylcholine receptor in membrane vesicles isolated from Torpedo californica have been labeled with the photoactivated hydrophobic probe, [3H]adamantanediazirine, which selectively labels regions of integral membrane proteins in contact with the hydrocarbon core of the lipid bilayer. As all of the homologous subunits are exposed to the lipid bilayer, it is probable that they each interact with the surrounding membrane in a similar fashion. All four subunits of the acetylcholine receptor in membrane vesicles isolated from Torpedo californica have been labeled with [3H]cholesteryl diazoacetate. As this probe incorporates into lipid bilayers analogously to cholesterol, this result indicates that acetylcholine receptor interacts with cholesterol. This investigation also demonstrates that this probe is a useful reagent for studying the interaction of cholesterol with membrane proteins. Since the photogenerated carbene is situated near the lipid-water interface, this probe has potential as a topographic tool for mapping membrane protein structure. The labeling studies with both [3H]adamantanediazirine and [3H]cholesteryl diazoacetate support the concept that the acetylcholine receptor is a pseudosymmetric complex of homologous subunits, all of which interact with and span the membrane. The syntheses of the fluorine-containing agonists for the Torpedo californica nicotinic acetylcholine receptor, fluoroacetylcholine bromide and p-fluorophenyltrimethylammonium iodide, are described. It is demonstrated that both are agonists using a cation flux assay with acetylcholine receptor enriched membrane vesicles. The potential for their use in ligand binding studies using 19F NMR spectroscopy is discussed. The affinity cleavage reagent, p-thiocyanophenyltrimethylammonium iodide, specifically cleaves a peptide bond of the nicotinic acetylcholine receptor in membrane vesicles isolated from Torpedo californica. It is demonstrated that this reagent is an agonist using a cation flux assay. The cleavage is blocked by stoichiometric quantities of α-bungarotoxin. The yield of the cleavage reaction is reduced with addition of the agonist, phenyltrimethylammonium iodide. This affinity cleavage reaction provides evidence for a low-affinity binding site for agonists on the 60K subunit.</p

Synthesis, Molecular Structure and Dynamic Behaviour of the Chiral Cluster (u*H)4Ru4(CO)9(HC(PPh2)3)

The synthesis and study of the dynamic behaviour of (u*H)4Ru4(CO)9(HC(PPh2)3) are described. The X-ray structural determination shows this cluster to be chiral, the asymmetry arising from a helical array of phenyl groups on the tripod ligand