Preliminary results on the 2p levels of krypton obtained by the Hanle effect

Using Hanle experiments in a discharge, the radiative lifetimes of 7 out of the ten 2p-levels of krypton have been studied as well as the cross-sections for the destruction of alignment in these levels by collisions with ground-state krypton atoms. The limitations of the present experimental method are emphasized and plans for future improvements are formulated.     

Adsorption thermodynamics of short-chain peptides on charged and uncharged nanothin polymer films

The present work describes experimental measurements of submolecular-level interaction energies involved in the process of peptide adsorption on polymer films using surface plasmon resonance spectroscopy. Gibbs energy change on adsorption (DeltaG(ad)) for tyrosine, phenylalanine, and glycine homopeptides were measured at 25 degrees C and pH 7 on highly uniform, nanothin polymer films, and the results were used to predict DeltaG(ad) for homologous homopeptides with a larger number of residue units. Nanothin poly(2-vinylpyridine), poly(styrene), and poly(1-benzyl-2-vinylpyridinium bromide) films were used for the adsorption studies; they were prepared using a graft polymerization methodology. In-situ swelling experiments were done with ellipsometry to examine the uniformity of the surfaces and to ensure that the graft densities of the different polymer films were similar to facilitate the comparison of adsorption results on these surfaces. The swelling experiments showed that the films were uniform, and the grafting densities were found to be 0.14-0.17 chains/nm(2). For uncharged surfaces, predicted and measured DeltaG(ads) values for homopeptides deviated by < or =4.9%. To extend this approach to a mixed-residue peptide, measurements were made for glycine, phenylalanine, and tyrosine-leucine subunits found in leucine enkephalin. The predicted DeltaG(ads) values for leucine enkephalin deviated by 3.0% and -9.1% for poly(2-vinylpyridine) and poly(styrene) films, respectively. Deviations between measured and predicted adsorption energies were larger for the charged poly(1-benzyl-2-vinylpyridinium bromide) surface relative to uncharged surfaces. While the adsorption energies were found to be additive within experimental uncertainties for the charged surface, generally speaking, measured uncertainty values were also larger for the charged surface.     

Development of a model of focal pneumococcal pneumonia in young rats

Background  

A recently licensed pneumococcal conjugate vaccine has been shown to be highly effective in the prevention of bacteremia in immunized children but the degree of protection against pneumonia has been difficult to determine.     

A short and efficient synthesis of 4a-substituted cis-hexahydro-1,2,3,4,4a,9a-carbazol-4-ones

Photocyclization of tertiary aryl enaminones 1 gave trans-hexahydrocarbazol-4-ones 2 which were subsequently alkylated with a series of electrophiles via the corresponding thermodynamic anion. The 4a-substituted derivatives formed were shown to have the cis-hexahydrocarbazol-4-one structure by comparison with the previously prepared trans isomer.     

Asymmetric synthesis VII: enantiospecific preparation of β-aminoalcohols from the n-cyanomethyl-4-phenyl-1,3-oxazolidine synthon

(-)-N-cyanomethyl-4-phenyl-1, 3-oxazolidine 1 has been investigated as chiral template for the enantiospecific synthesis of β-aminoalcohols. (-)-2(R)-hydroxy-3(S)-nonylamine 5a was chosen as a target molecule of the new method.