Meson-nucleon coupling constants in a quark model

An effective vector exchange in a quark model, previously used for nucleon-antinucleon annihilation and meson decays, is applied to nucleon-meson and decuplet baryon-meson couplings. A reasonable fit to experimental data is obtained.This article is written in honour and memory of Michael Moravcsik. He was both a dedicated physicist and a very humane person with wide interests in the world around him. One of us (EMH) knew him well and will continue to cherish his friendship     

Engineering the plasmon resonance of large area bimetallic nanoparticle films by laser nanostructuring for chemical sensors

Large area fabrication of metal alloy nanoparticles with tunable surface plasmon resonances on low-cost substrates is reported. A UV excimer laser was used to anneal 5 nm thick Ag Au bilayer films deposited with different composition ratios to create alloy nanoparticles. These engineered surfaces are used to investigate how the wavelength of the surface plasmon resonance affects the optical detection capability of chemical species by surface-enhanced Raman spectroscopy.     

Parity violation: Radiative pion capture in hydrogen

We investigate radiative pion capture in hydrogen, π^? → nγ, as a means of determining the parity-violating πNN coupling constant ?_π. We include contributions from the lightest baryon resonance [Δ(1232)] and the light vector mesons [ρ, ω, φ]. Our results indicate that, despite their negligible role in parity-conserving amplitudes, the effects of the Δ and ρ may hamper the determination of ?_π.     

Classical many-body model for heavy-ion collisions incorporating the Pauli principle

A classical model for heavy-ion collisions, introduced previously, has been extended to include certain effects of the Pauli principle. All nucleons are treated equally. They obey classical dynamics and interact through an ordinary two-body force and through a momentumdependent two-body “Pauli core” which satisfies, approximately, that $\text{p}{}_{\mathrm{ij}}\text{r}{}_{\mathrm{ij}}\text{≧ξ}\text{h}\text{?}$, where ξ is a dimensionless constant. A form for the Pauli core is presented. The ordinary two-body force has been adjusted to fit bulk properties of nuclei and to reproduce that moment of nucleon nucleon scattering cross sections which is relevant to hydrodynamics. The parameters of the forces are given.     

Parity violation in electron-deuteron scattering I. Methodology and elastic scattering

In this paper, we present methodology for investigating theoretically parity violation in both the elastic and break-up channels of electron-deuteron scattering, restricting ourselves to energies in which non-relativistic expansions are allowed for nucleons. The deficiency in the standard impulse approximation related to gauge invariance is remedied by relating it to the “elementary-particle” treatment. Results for parity violation in elastic electrondeuteron scattering are presented and discussed.     

High electric field strength two-dimensional peptide separations using a microfluidic device

New instrumentation has been developed to improve the resolution, efficiency, and speed of microfluidic 2D separations using MEKC coupled to high field strength CE. Previously published 2D separation instrumentation [Ramsey, J. D. et al., Anal. Chem. 2003, 75, 3758-3764] from our group was limited to a maximum potential difference of 8.4 kV, resulting in an electric field strength of only approximately 200 V/cm in the first dimension. The circuit described in this report has been designed to couple a higher voltage supply with a rapidly switching, lower voltage supply to utilize the best features of each. Voltages applied in excess of 20 kV lead to high electric field strength separations in both dimensions, increasing the separation resolution, efficiency, and peak capacity while reducing the required analysis time. Detection rates as high as six peptides per second (based on total analysis time) were observed for a model protein tryptic digest separation. Additionally, higher applied voltages used in conjunction with microfluidic chips with longer length channels maintained higher electric field strengths and produced peak capacities of over 4000 for some separations. Total separation time in these longer channel devices was comparable to that obtained in short channels at low field strength; however, resolving power improved approximately threefold.     

The hydroxyl radical reaction rate constant and products of cyclohexanol

The gas phase reaction of the hydroxyl radical (OH) with cyclohexanol (COL) has been studied. The rate coefficient was determined to be (19.0 ± 4.8) × 10⁻¹² cm³ molecule⁻¹ s⁻¹ (at 297 ± 3 K and 1 atmosphere total pressure) using the relative rate technique with pentanal, decane, and tridecane as the reference compounds. Assuming an average OH concentration of 1 × 10⁶ molecules cm⁻³, an atmospheric lifetime of 15 h is calculated for cyclohexanol. Products of the OH + COL reaction were determined to more clearly define COL's atmospheric degradation mechanism. The observed products and their formation yields were: cyclohexanone (0.55 ± 0.06), hexanedial (0.32 ± 0.15), 3‐hydroxycyclohexanone (0.31 ± 0.14), and 4‐hydroxycyclohexanone (0.08 ± 0.04). Consideration of the potential reaction pathways suggests that each of these products is formed via hydrogen abstraction at a different site on the COL ring. The products and their relative amounts are discussed in light of the predicted yields for each reaction channel. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 108–117, 2001