Synthesis and characterization of CdS nanoparticles embedded in a polymethylmethacrylate matrix

CdS nanopowder capped with sodium bis(2-ethylhexyl)sulfosuccinate was synthesized by using water-in-oil microemulsions. The CdS nanoparticles of about 5 nm obtained were embedded in polymethylmethacrylate matrix by a photocuring process. The transparent yellow solid compound was characterized by optical absorption and emission spectroscopy, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The properties of this compound were compared with those of the nanopowder dispersed in heptane and in methylmethacrylate. The results obtained indicate that the nanoparticles are homogeneously dispersed in the matrix and do not change in size during the embedding process. Even if the surface slightly changes its luminescence properties, as a consequence of the different new chemical environment, the final product seems to be suitable for practical applications.     

Product Semigroups and Extrapolation Spaces

A new formulation of the theory of extrapolation spaces is used to recast a theorem on the resolvent of the sum of a generator of a semigroup and a Hille–Yosida operator and to prove a regularity result related to an abstract equation.     

Folding degrees of azurins and pseudoazurins. Implications for structure and function

A quantitative measure of the degree of folding of azurins and pseudoazurins has been made. We have found that the reduction potential of azurins and pseudoazurins is a function of the contribution to the degree of folding of His117, a key amino acid in electron transfer which is directly bonded to copper in these proteins. The folding degree of His117 explains 95% of the variance in the experimental values of the reduction potential of azurins and pseudoazurins. The change in the folding degree of this amino acid influences several geometric parameters of the main backbones of these proteins. Among them, the angle formed between N(His117)...Cu...S(Cys112), which plays an important role in electron transport, but not the N(His117)...Cu distance, shows some non-linear correlation with the reduction potential of azurins and pseudoazurins. However, it is only able to explain less than 75% in the variance of the reduction potential of these proteins instead of the 95% explained by the folding degree of His117.     

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.