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The tensile and elastic properties of melt spun threads of segmented copolymers based on T6T6T-dimethyl (5-16wt%) and PTMO 1000 /DMT of different lengths (3000-10,000 g/mol) are very good. Stress-strain measurements show that extruded threads of these polymers have high fracture strains (>1000%) and little strain hardening. The modulus and yield stress increase with increasing...
We investigated the behavior of the conformations of Chymotrypsin Inhibitor (CI2) from the native to the denatured states, obtained in Monte Carlo (MC)/Metropolis simulations, where a low-resolution model is used together with knowledge-based potentials. New conformations starting from the X-ray native structure are generated by random perturbations along with a constraint to increase the radius of...
In this contribution we analyse sorption and transport of several gases in semicrystalline syndiotactic polystyrene with nanoporous crystalline δ form. Investigation was performed on amorphous samples and on samples characterized by different degrees of crystallinity. Sorption isotherms of carbon dioxide, nitrogen and oxygen in the crystalline phase have been determined starting from experimental...
The transfer matrix method for generating lattice conformations of proteins is explained and applied to lattice proteins having high-level cooperativity to represent hydrophobic interactions. The main advantage of the method is the extremely efficient attrition-free generation and enumeration of compact conformations. We review the application of the method for the generation and complete, exact enumeration...
A series of copolymers were prepared by an oxidative polymerization of pyrrole (PY) and 2-ethylaniline (EA) in HCl. The polymerization process was followed by tracking open-circuit potential and temperature of the reaction solutions. The fine particles of the PY/EA copolymers obtained in situ were further N-nitrosated for the first time in order to improve their solubility. The size, structure, and...
Only about 1000 qualitatively different protein folds are believed to exist in nature. Here, we review theoretical studies which suggest that some folds are intrinsically more designable than others, i.e. are lowest energy states of an unusually large number of sequences. The sequences associated with these folds are also found to be unusually thermally stable. The connection between highly designable...
Two different computational methods are employed to predict protein folding nuclei from native state structures, one based on an elastic network (EN) model and the other on a constraint network model of freely rotating rods. Three sets of folding cores are predicted with these models, and their correlation against the slow exchange folding cores identified by native state hydrogen-deuterium exchange...
Regular micrometer-size porous polystyrene film is prepared by water droplet templating, i.e. breath figures are stabilized by the polymer in solution and thermocapillary flow arranges them into ordered packing. The influences of polystyrene molecular weight, solvent properties, and the relative humidity of atmosphere on the pattern formation and hole sizes are investigated. Two different kinds of...
The anti-fouling properties and blood compatibility of poly(acrylonitrile-co-maleic acid) (PANCMA) membranes were improved by the immobilization of poly(ethylene glycol)s (PEG) on membrane surface. It was found that the reactive carboxyl groups on PANCMA membrane surface could be conveniently conversed into anhydride groups and then esterified with PEG. Chemical and morphological changes as well as...
The micellization of ionic amphiphilic diblock copolymers, polyisobutylene-block-poly(methacrylic acid) (PIB-b-PMAA), with a constant degree of polymerization of the non-ionic block (DP n =20) and various degrees of polymerization of the polyelectrolyte block (DP n =100-425) was examined in aqueous media by means of fluorescence spectroscopy using pyrene as a polarity probe. The molar...
Polymer/clay nanocomposites have been observed to exhibit enhanced mechanical properties at low weight fractions (W c ) of clay. Continuum-based composite modeling reveals that the enhanced properties are strongly dependent on particular features of the second-phase 'particles'; in particular, the particle volume fraction (f p ), the particle aspect ratio (L/t), and the ratio of particle...
We propose a novel combinatorial algorithm for efficient generation of Hamiltonian walks and cycles on a cubic lattice, modeling the conformations of lattice toy proteins. Through extensive tests on small lattices (allowing complete enumeration of Hamiltonian paths), we establish that the new algorithm, although not perfect, is a significant improvement over the earlier approach by Ramakrishnan et...
Hydrophobically modified water-soluble polymers have been prepared by micellar copolymerization of hydrophilic monomer acrylamide and the silicone-containing hydrophobic comonomer, tris(trimethylsiloxy)methacryloxypropylsilane in various molar ratios. Capillary viscometer, FT-IR, gel permeation chromatography-multi-angle laser light scattering, transmission electron microscopy, and 1 H NMR...
The solution copolymerization of styrene/butyl acrylate in toluene was monitored off-line using an ATR-FTIR probe. The probe was used to track the concentration of the starting materials, thereby providing conversion and polymer composition data. Off-line gravimetry and 1 H NMR spectroscopy were used as standard methods to provide a comparison to the ATR-FTIR data. A non-calibrated univariate...
Series approximations of the three-dimensional structure of protein conformations can provide insightful ways to detect and manipulate global features and those local to contiguous segments of the chain. Discrete cosine transforms have proven to be very useful in the past, and now wavelet transforms appear to have additional advantages. Here the emphasis is on a new generalization of the discrete...
Using first-principles calculations, we find that the electronic structures of PBT, OH-PBT, OH-PBI, and OH-PBI(N) rigid-rod polymers are very different from those of conventional semiconductors. The close agreement between calculated excitation energies and the observed features in the ultraviolet-visible (UV-Vis) absorption spectra enables us to identify that the major features in the UV-Vis absorption...
By means of full atomistic molecular dynamics simulation, the solubility parameters for pure poly(3-hydroxybutyrate) and poly(ethylene oxide) are calculated and the results are in agreement with the literature values. Furthermore, in order to reveal the blend property, the volume-temperature curve of the PHB/PEO blend system (1:2 blends in terms of repeated units) is simulated by employing the united...
Copolymer ethylene-dimethyl-aminoethyl methacrylate (EDAM) with 3.9% DAM side groups and ultra-high molecular weight polyethylene (UHMWPE) were blended in decalin solvent. The hot homogenized solution was poured into an aluminum tray to form gels and the decalin was allowed to evaporate from the resultant gels under ambient condition. Surprisingly, the resultant dry blend films could be elongated...
Successful application of physics-based protein-structure prediction methods depends on sophisticated computational approaches to global optimization of the conformational energy of a polypeptide chain. One of the most effective procedures for the global optimization of protein structures appears to be the Conformational Space Annealing (CSA) method. CSA is a hybrid method which combines genetic algorithms,...
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