Observation of spin-orbit splitting in lambda single-particle states

The spin-orbit splitting of Lambda single-particle states in (13)(Lambda)C was measured. The 13C(K-,pi(-))(13)(Lambda)C reaction was used to excite both the 1/2(-) and 3/2(-) states simultaneously, which have predominantly 12C(0(+)) x p(Lambda) configuration. gamma rays from the states to the ground state were measured in coincidence with the pi(-)'s, by which ls splitting was found to be 152+/-54(stat)+/-36(syst) keV. The value is 20-30 times smaller than exhibited by the ls splitting in the nuclear shell model. This value gives us new insight into the YN interaction.     

Designing antibacterial compounds through a topological substructural approach

A novel application of TOPological Substructural MOlecular DEsign (TOPS-MODE) was carried out in antibacterial drugs using computer-aided molecular design. Two series of compounds, one containing antibacterial and the other containing non-antibacterial compounds, were processed by a k-means cluster analysis in order to design training and predicting series. All clusters had a p-level < 0.005. Afterward, a linear classification function has been derived toward discrimination between antibacterial and non-antibacterial compounds. The model correctly classifies 94% of active and 86% of inactive compounds in the training series. More specifically, the model showed a global good classification of 91%, i.e., 263 cases out of 289. In predicting series, the model has shown overall predictabilities of 91 and 83% for active and inactive compounds, respectively. Thereby, the model has a global percentage of good classification of 89%. The TOPS-MODE approach, also, similarly compares with respect to one of the most useful models for antimicrobials selection reported to date.     

A new environment-sensitive fluorescent amino acid for Fmoc-based solid phase peptide synthesis

A new 4-(N,N-dimethylamino) phthalimide-based environment-sensitive fluorescent building block for solid phase peptide synthesis, has been synthesized and incorporated into peptides. Peptides incorporating this residue show great potential for biological applications in sensing protein/protein interactions.     

General method for the synthesis of caged phosphopeptides: tools for the exploration of signal transduction pathways

[reaction: see text] An interassembly approach for the synthesis of peptides containing 1-(2-nitrophenyl)ethyl-caged phosphoserine, -threonine, and -tyrosine has been developed. Photochemical uncaging of these peptides releases the 2-nitrophenylethyl protecting group to afford the corresponding phosphopeptide. The peptides described herein are based on phosphorylation sites of kinases involved in cell movement or cell cycle regulation and demonstrate the versatility of the method and compatibility with the synthesis of polypeptides, including a variety of encoded amino acids.     

Production of (4)(double Lambda)H hypernuclei

An experiment demonstrating the production of double-Lambda hypernuclei in (K(-),K(+)) reactions on (9)Be was carried out at the D6 line in the BNL alternating-gradient synchrotron. The technique was the observation of pions produced in sequential mesonic weak decay, each pion associated with one unit of strangeness change. The results indicate the production of a significant number of the double hypernucleus (4)(double Lambda)H and the twin hypernuclei (4)(Lambda)H and (3)(Lambda)H. The relevant decay chains are discussed and a simple model of the production mechanism is presented. An implication of this experiment is that the existence of an S = -2 dibaryon more than a few MeV below the double Lambda mass is unlikely.     

Nonlinear eigenvalue problems for quasilinear operators on unbounded domains

We prove several existence results for eigenvalue problems involving the p-Laplacian and a nonlinear boundary condition on unbounded domains. We treat the non-degenerate subcritical case and the solutions are found in an appropriate weighted Sobolev space. Received May 2000     

Sulfide-Oxidizing Autotrophic Denitrification: an Evaluation for Nitrogen Removal from Anaerobically Pretreated Domestic Sewage

Nitrogen removal from effluents of anaerobic reactors using conventional nitrification/denitrification processes depends on the availability of electron donors for denitrification. As sulfide is normally present in such effluents, autotrophic denitrification using sulfide can be an alternative to avoid or reduce the requirements of exogenous organic carbon sources. This study evaluated the application of sulfide-oxidizing autotrophic denitrification to anaerobically pretreated domestic sewage. A denitrifying reactor was fed with a mixture, at different proportions, of anaerobically pretreated (containing sulfides and residual organic matter) and nitrified (containing nitrates) effluents produced by reactors treating synthetic domestic sewage. Autotrophic denitrification was responsible for most of the nitrogen removal and coexisted with heterotrophic activity, resulting in high denitrification efficiencies. Efficient denitrification could be attained at a molar NO₃ ^?/S^2? ratio of 2.1, higher than values reported before, and this represents an important parameter for the strategic application of the process. Under the experimental conditions studied, autotrophic denitrification showed to be an efficient and feasible alternative to conventional denitrification using exogenous electron donors.