Complex homogeneous spaces of real groups with top homology in codimension two

SupposeX=G/H is a connected homogeneous complex manifold, whereG is a Lie group andH is a closed subgroup. Assume (X) and letG/H G/I be the holomorphic reduction ofX. If the top nonvanishing homology group ofX with coefficients in ₂ is in codimension two, then either a complex Lie group acts tansitively onG/I (see [3]) orG/I is biholomorphic to the unit disk.Partially supported by NSERC Grant A3494 and by the Deutsche Forschungsgemeinschaft     

Vapor shielding and erosion of surfaces exposed to a high heat loadin an electrothermal accelerator

The experimental and theoretical verification of the vapour shield concept in an electrothermal accelerator is reported. Measurements of the ablation mass loss of the insulator material (Lexan) demonstrate that the energy transmission factor through the vapor shield is of the order of 10%. If enough vapor is produced under high heat flux, the vapor shield mechanism will help limit the surface erosion in electromechanical devices. The erosion of the barrel material (aluminum) has a strong axial dependence, and the erosion depth increases with input energy     

4-(Trinitromethyl)tetrahydro-2-furanol and 4-(fluorodinitromethyl)tetrahydro-2-furanol via lactone reduction with borane. The preparation of cis/trans-2-polynitroalkoxy-4-polynitromethyltetrahydrofurans

Normally borane reduces lactones too rapidly to allow the isolation of intermediates but 4-(trinitromethyl)-tetrahydro-2-furanol and 4-(fluorodinitromethyl)tetrahydro-2-furanol are isolated in 72 and 36% yield from the reduction of 4-hydroxy-3-(trinitromethyl)butyric acid, γ-lactone and 4-hydroxy-3-(fluorodinitromethyl)-butyric acid, γ-lactone with borane-tetrahydrofuran complex. The preparation of 2-polynitroalkoxy-4-polynitromethyltetrahydrofurans from the 2-furanols is described.     

Synthesis of a functionalized D-glucose: A synthon for the carbomycins (magnamycins)

D-Glucose has been converted into its functionalized derivative $\text{7b}$ a synthon (C₁–C₆) of the carbomycin macrolide antibiotics.     

International inter-comparison exercise on $${}^{153}\hbox {Sm}$$

Samarium-153 (\({}^{153}\hbox {Sm}\)) is a short-lived radionuclide that decays to stable europium-153 via beta emission, with subsequent de-excitation via gamma emission and internal conversion. Historical measurements of \({}^{153}\hbox {Sm}\) by gamma spectrometry and beta liquid scintillation counting have shown a low bias compared to beta proportional counting. In order to investigate this, four national laboratories jointly conducted an experimental inter-comparison exercise on a certified \({}^{153}\hbox {Sm}\) sample, created from neutron activation of samarium-152. Radiometric measurements were conducted using gamma spectrometry, liquid scintillation counting, gas proportional counting, and passivated implanted planar silicon detectors and compared across the four institutions against the certified value. The results from this experiment are presented together with a number of conclusions which suggest that the current published cumulative fission yield for \({}^{153}\hbox {Sm}\), as used by many laboratories, is approximately 15% high and is the likely cause of the previously observed bias.     

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Solvation of propanediol ions by water molecules in the gas phase

The thermochemical properties of protonated hydrates of 1,2- and 1,3-propanediols have been investigated using electrospray ionization-high pressure mass spectrometry. The binding enthalpies, entropies, and free energies of the stepwise hydration of protonated propanediols with one to three waters are reported. The observed negative entropy change [ΔΔS_1,3^o for the addition of the third water to 1,3-propanediol·H⁺(H₂O)₂ suggests a stable structure due to an increased number of hydrogen bonds and the loss of the intramolecular hydrogen bond in the water cluster ion. The thermochemical properties of two isomers of butanediol were also investigated in order to further elucidate the structures of the protonated propanediols.