A kinematical model for quarks and hadrons

Starting from simple topological arguments due to Dirac on the classical rotational properties of extended rigid bodies, we abstract the concept of a finite-size spinor (FSS). The FSS is a concept distinct from both point spinors (e.g., electrons) and composite spinors (e.g., nuclei), and suggests a new model for baryons. The FSS offers a natural explanation of threeness for the quarks, excludes the existence of free quarks, denies the operational definition of quark spin statistics, and, moreover, leads to the dual model of hadronic interactions.Research supported in part by the National Science Foundation, the Army Research Office (Durham), and the U.S. Atomic Energy Commission.     

Regression estimation for bivariate normal distributions

Summary In estimating the mean μ _y of one variable in a bivariate normal distribution, the experimenter can use the other variable,x, as an auxiliary variable to increase precision. In particular, if μ _x is known, he can use the regression estimator. When μ _x is unknown, a preliminary test can be performed and the estimator will be made to depend on the result of the preliminary test. The bias and mean square error of the preliminary test estimator are obtained and the relative efficiency is are discussed.     

Reduced data acquisition time in multi-dimensional NMR spectroscopy using multiple-coil probes

A new hardware-based approach is presented to reduce data acquisition times in multi-dimensional NMR spectroscopy using a multiple-coil probe. Using a four-coil setup, two-dimensional COSY and TOCSY spectra were acquired in one-quarter the time of conventional spectra by simultaneous acquisition of different effective t1 evolution times for each coil. Data processing consists of simple phase-shifting and intensity normalization of the individual data sets, and results in spectra almost identical to those acquired in a conventional manner. This method can potentially be integrated with other new data acquisition and processing schemes for further increases in data acquisition speed.     

Sonocatalytic degradation of methyl orange in the presence of TiO2 catalysts and catalytic activity comparison of rutile and anatase

Rutile and anatase titanium dioxide (TiO(2)) powders were used as sonocatalysts for the degradation of methyl orange which was used as a model compound. Ultrasound was used as an irradiation source. It was found that the sonocatalytic degradation ratios of methyl orange in the presence of TiO(2) powder were much better than ones without any TiO(2), but the sonocatalytic activity of rutile TiO(2) particles was obviously higher than that of anatase TiO(2) particles. Although there are many factors influencing sonocatalytic degradation of methyl orange, the experimental results show that the best degradation ratio of methyl orange can be obtained when the experimental conditions of the initial methyl orange concentration of 10 mg/l, rutile TiO(2) added amount of 500 mg/l, ultrasonic frequency of 40 kHz, output power of 50 W, pH=3.0 and 40 degrees C within 150 min were adopted. In addition, the catalytic activity of reused rutile TiO(2) catalyst was also studied and found to be better than new rutile TiO(2) catalyst sometimes. All experimental results indicated that the method of the sonocatalytic degradation of organic pollutants in the presence of TiO(2) powder was an advisable choice for treating non- or low-transparent organic wastewaters.     

Study of 19Na at SPIRAL

The excitation function for the elastic-scattering reaction p( ¹⁸Ne, p) ¹⁸Ne was measured with the first radioactive beam from the SPIRAL facility at the GANIL laboratory and with a solid cryogenic hydrogen target. Several broad resonances have been observed, corresponding to new excited states in the unbound nucleus ¹⁹Na. In addition, two-proton emission events have been identified and are discussed.     

Structural changes of purple membrane and bacteriorhodopsin during its denaturation induced by high pH

Bacteriorhodopsin (bR) trimers naturally form two-dimensional hexagonal crystals in purple membrane (PM), which make it very stable. However, the dnaturation of bR was found to occur during a very narrow pH range when the pH was increased above 12.0, as indicated by inactivation of the photochemical cycle observed by flash photolysis kinetic spectra. Here, atomic force microscopy was used to study the surface structural changes of PM during the denaturation process induced by high pH. Together with the absorption and fluorescence spectra, it was found that the structural changes could be divided into three steps. First, some hydrophobic amino acids of bR become exposed to the aqueous environment and PM loses its 2D crystalline structure, transforming into the so-called "nonisland" structure. Second, bR molecules are extracted out of membrane and form protrusions on the surface like islands in the sea; therefore, the "nonisland" structure transforms into the "island" structure. Finally, most bRs break off from the membrane and form large depositions.     

Theoretical study of the effect of water in the process of proton transfer of glycinamide

For the purpose of investigating the tautomerism from glycinamide (G) to glycinamidic acid (G*) induced by proton transfer, we carried out a study of structural interconversion of the two tautomers and the relative stabilizing influences of water during the tautomerization process. Throughout the study, we used density functional theory (DFT) calculations at the B3LYP/6-311++G** level of theory, also considering the correction functions, that is, the effect of basis set superposition error (BSSE). Totally, 42 geometries, including fourteen important transition states, were optimized, and their geometric parameters have also been discussed in detail. Water molecules were gradually put in three different regions in the vicinity of G and its tautomer G*. The calculation results indicate that water in two of these regions can protect G from tautomerizing to G*, while in another region, water can assist in the tautomerism; this reveals that water molecules have stabilization and mutagenicity effects for G simultaneously.     

A partition coefficient calculation method with the SFED model

The Solvation Free Energy Density (SFED) model, a solvation model proposed by No et al. was modified to give better solvation free energies of the molecules having high polarizable groups. The SFED at a point around the molecule was represented by a linear combination of four basis functions, the contribution from the cavitation free energy of a solvent, and a constant. As an application of the SFED model, the linear expansion coefficients of the Hydration Free Energy Density (HFED) and the 1-Octanol Free Energy Density (1-OFED) were determined. Both calculated hydration free energy and 1-octanol solvation free energy of selected 95 organic molecules agreed well with experimental values. The standard errors were 0.47 and 0.39 kcal/mol, respectively. 1-Octanol/water partition coefficients (P) of the molecules were calculated from the difference of the HFE and 1-OFE of the molecules. At the same time, the logP density (LPD) of a molecule was represented by the same basis functional form with the SFED model. The logP of a molecule can be obtained by the integration of the LPD of the molecule. The coefficients of the basis functions were determined by using experimental logP as constraints through an optimization procedure. Both logPs calculated from the free energy difference and from the LPD agreed well with the experimental data. The absolute mean errors were obtained as 0.34 and 0.32, respectively.