Gauged N = 8 supergravity in five dimensions

We construct gauged N = 8 supergravity theories in five dimensions. Instead of the twenty-seven vector fields of the ungauged theory, the gauged theories contain fifteen vector fields and twelve second-rank antisymmetric tensor fields satisfying self-dual field equations. The fifteen vector fields can be used to gauge any of the fifteen-dimensional semisimple subgroups of SL(6,R), specially SO(p, 6?p) for p = 0, 1, 2, 3. The gauged theories also have a physical global SU(1,1) symmetry which survives from the E₆₍₆₎ symmetry of the ungauged theory. This SU(1,1) for the SO(6) gauging is presumably related to that of the chiral N = 2 theory in ten dimensions. In our formalism we maintain a composite local USp(8) symmetry analogous to SU(8) in four dimensions.     

Detection of homocysteine and cysteine

At elevated levels, homocysteine (Hcy, 1) is a risk factor for cardiovascular diseases, Alzheimer's disease, neural tube defects, and osteoporosis. Both 1 and cysteine (Cys, 3) are linked to neurotoxicity. The biochemical mechanisms by which 1 and 3 are involved in disease states are relatively unclear. Herein, we describe simple methods for detecting either Hcy or Cys in the visible spectral region with the highest selectivity reported to date without using biochemical techniques or preparative separations. Simple methods and readily available reagents allow for the detection of Cys and Hcy in the range of their physiologically relevant levels. New HPLC postcolumn detection methods for biological thiols are reported. The potential biomedical relevance of the chemical mechanisms involved in the detection of 1 is described.     

Micro-X-ray fluorescence as a general high-throughput screening method for catalyst discovery and small molecule recognition

A powerful high-throughput screening technique is described for the rapid screening of bead-based libraries for catalyst discovery and molecular recognition. Micro-X-ray fluorescence (MXRF) screens materials for elemental composition with mesoscale analysis. This method is nondestructive and requires minimal sample preparation and no special tags for analysis, and the screening time is dependent on the desired sensitivity. The speed, sensitivity, and simplicity of MXRF as a high-throughput screening technique were applied to screen bead-based libraries of oligopeptides for phosphate hydrolysis catalysts and molecular recognition of selective receptors for the degradation products and analogues of chemical warfare agents. This paper demonstrates the analytical or HTS capability of MXRF for combinatorial screening. It is meant only to show the capabilities of MXRF and is not meant as an exhaustive study of the catalyst and molecular recognition systems presented.     

Investigation of induced circular dichroism of benzo(a)pyrene cyclodextrin complexes

This study focuses on the inclusion complexes of -,- and-cyclodextrins with benzo (a) pyrene, as indicated by induced circular dichroism data. The benzo(a)pyrene complex exhibits a significant induced ellipticity in the presence of-cyclodextrin, while the other two cyclodextrins did not produce a significant induced circular dichroism signal. In the presence of deuterium oxide, which is larger than the water molecule, the ellipticity is larger. The changes in ellipticity with increasing cyclodextrin concentration are observed to follow the changes in equilibrium of the pyrene--cyclodextrin system. The study of these systems using circular dichroism measurements yields a method of estimating the possible stoichiometry of this complex.     

Theory of light scattering from vesicles

The scattering and depolarization of light from spherical membrane systems, vesicles, is calculated in a new succinct formalism appropriate to spherical systems and the rotations of anisotropic elements composing them. The results of Tinker (1972) and Mishima (1980, 1981) are readily derived within this formalism and there is a considerable saving in numerical computation. The problem of fluctuations in the molecular packing of the component phospholipid molecules is also addressed.     

Trichlorosilane mediated asymmetric reductions of the C=N bond

Chiral amines are key components in numerous bioactive molecules. The development of efficient and economical ways to access molecules containing this functional group still remains a challenge at the forefront of synthetic chemistry. Of the methods that do exist, the trichlorosilane mediated organocatalytic reduction of ketimines offers significant potential as an alternative strategy. In this perspective, we wish to highlight the progress made in the past decade in this field and offer a direct quantitative comparison to transition-metal mediated process.