Additives to polymeric materials can lead to appreciable changes in the rates of relaxation and reaction in these mixtures that can profoundly alter material properties and function. We develop a general theoretical framework for quantifying changes in the "high-frequency" relaxation dynamics of mixtures based on classical transition state theory, in conjunction with mathematical statements reg...

During the past year the activities of the Chemical Thermodynamics Data Center and the JANAF Thermochemical Tables project have been combined to obtain an extensive collection of thermodynamic information for many chemical species, including the elements. Currently available are extensive bibliographic collections and data files of heat capacity, enthalpy, vapor pressure, phase transitions, etc...

We study the dynamics of DNA hairpin formation using oxDNA, a nucleotide-level coarse-grained model of DNA. In particular, we explore the effects of the loop stacking interactions and non-native base pairing on the hairpin closing times. We find a nonmonotonic variation of the hairpin closing time with temperature, in agreement with the experimental work of Wallace et al. (Proc. Natl. Acad. Sci...

The 32-residue leucine zipper subsequence, called here Jun-lz, associates in benign media to form a parallel two-stranded coiled coil. Studies are reported of its thermal unfolding/folding transition by circular dichroism (CD) on samples of natural isotopic abundance and by both equilibrium and spin inversion transfer (SIT) nuclear magnetic resonance (NMR) on samples labeled at the leucine-18 a...

(-)-Sparteine and TMEDA dramatically lower both enthalpy and entropy of activation for the barrier to enantiomerization of N-Boc-2-lithiopyrrolidine in diethyl ether, whereas N,N'-diisopropylbispidine has little effect; the entropy of activation for enantiomerization is zero in the presence of TMEDA and slightly negative in the presence of sparteine; these data suggest a subtle change in mechan...

The principal dielectric permittivity components in the nematic phase of 4-rc-hexyloxy-4'-cyanobiphenyl (60CB) were measured as functions of temperature at ambient pressure and as functions of pressure up to 100 MPa at several constant temperatures. The dielectric anisotropy is analized in the frame of the Maier-Meier equations. The pressure dependence of the order parameter is deduced. Prelimi...

We report the energetics of association in polymeric gels with two types of junction points: crystalline hydrophobic junctions and polymer-nanoparticle junctions. Time-temperature superposition (TTS) of small-amplitude oscillatory rheological measurements was used to probe crystalline poly(L-lactide) (PLLA)-based gels with and without added laponite nanoparticles. For associative polymer gels, ...

Reaction rates and selectivities were measured for transacylation of fatty acid esters in solvents catalysed by Candida antarctica lipase B and by cutinase from Humicola insolens. With these enzymes classical water-based enzymology can be expanded to many different solvents allowing large variations in interaction energies between the enzymes, the substrates and the surrounding. Further, hydrol...

a good understanding of adsorption equilibrium and thermodynamics is required to design and operate an adsorption process. this study was conducted to assess the adsorption percentage of pb2+ ions as a function of contact time, solution ph and temperatures, and adsorbent dosage through a series of batch experiments. the methods including zeta potentials, specific surface area measurements and t...