The energetics of the phenolic O-H bond in the three hydroxybenzoic acid isomers and of the intramolecular hydrogen O-H- - -O-C bond in 2-hydroxybenzoic acid, 2-OHBA, were investigated by using a combination of experimental and theoretical methods. The standard molar enthalpies of formation of monoclinic 3- and 4-hydroxybenzoic acids, at 298.15 K, were determined as Delta(f)(3-OHBA, cr) = -593....

We discuss models for the force-induced dissociation of a ligand-receptor bond, occurring in the context of cell adhesion or single molecule unbinding force measurements. We consider a bond with a structured energy landscape which is modeled by a network of force dependent transition rates between intermediate states. The behavior of a model with only one intermediate state and a model describi...

A gas chromatograph/electron capture detector-ion trap mass spectrometer (GC/ECD-ITMS) was used for the determination of polybrominated diphenyl ethers (PBDEs) in euryhaline fish and crabs. GC/ECD-ITMS results showed that average recoveries from the spiked fish samples are in a range of 58-123% with relative standard deviations (RSDs) of 5-19%. PBDE concentrations obtained from GC/ECD-ITMS rang...

High-level ab initio molecular orbital calculations are used to study the magnitude and origin of the penultimate unit effect in atom transfer radical polymerization (ATRP) of dimers involving the comonomers methyl acrylate (MA), methyl methacrylate (MMA), and propylene (P). The penultimate unit effects depend on the nature of the terminal unit and the halogen and can be significant, with the M...

The gas-phase thermochemistry of actinide monosulfides, AnS, was investigated experimentally and theoretically. Fourier transform ion cyclotron resonance mass spectrometry was employed to study the reactivity of An(+) and AnO(+) (An = Th, Pa, U, Np, Pu, Am and Cm) with CS(2) and COS, as well as the reactivity of the produced AnS(+) with oxidants (COS, CO(2), CH(2)O and NO). From these experimen...

The spirodienone structure in lignin is a relatively recent discovery, and it has been found to occur in lignin of various plant species at concentrations of ∼3%, which is sufficiently high to be important for better understanding of its properties and reactivity. The cyclic structure, with a β-1 bond, has been proposed to be a precursor for acyclic β-1 linkages in lignin. Previous analytical w...

Blood and/or breast milk have been used to assess human exposure to various environmental contaminants. Few studies have been available to compare the concentrations in one matrix with those in another. The goals of this study were to determine the current levels of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in Japanese women, with analysis of the effects of lif...

Green fluorescent proteins bearing the Y66H mutation exhibit strongly blue-shifted fluorescence excitation and emission spectra. However, these blue fluorescent proteins (BFPs) have lower quantum yields of fluorescence (Phi(f) approximately 0.20), which is believed to stem from the increased conformational freedom of the smaller chromophore. We demonstrate that suppression of chromophore mobili...

Polybrominated diphenyl ethers (PBDEs) have been used as flame retardants. Although many reports have indicated an association between exposure to PBDEs and developmental neurotoxicity, the relative contributions of different sources of dust PBDE congeners to the levels in various tissues of mother-baby pairs is not well understood. The aims of this study were thus to measure the quantitative r...