Flammability of wood-polypropylene composites

Addition of wood particles to polymers can cause a change of properties of the composites which depends on features of lignocellulosic materials and those of polymers. It is also observed in the flammability characteristics of the composites.In this work, the flammability of polypropylene composites with pine wood particles obtained by extrusion and press moulding was analyzed. The amount of wood particles was 50%. Polymers with various melt flow index (MFI) were used (Malen F-401, PP HY-202 and Malen S-702).The samples were tested using Cone Calorimeter at heat flux of 35 kW/m². Heat release rate (HRR) curves of composites show that thermal decomposition depends on the kind of polypropylene used. In the presence of PP HY-202 and Malen S-702, the flammability characteristic is similar to that of lignocellulosic materials, in contrast to composites with matrices prepared from Malen F-401. The observed phenomenon is interpreted in terms of the wettability of particles of pine wood by polymers of varying melt viscosity.     

Electrical behavior of molecular junctions incorporating alpha-helical peptide

We synthesized an alpha-helical peptide containing two terminal thiol groups and demonstrated the method of preparation of a self-assembled monolayer (SAM) on gold with uniform orientation of the molecules on the surface. The monolayers were employed as model systems for the investigations of mediated electron transfer. The measurements of electron transfer efficiency through the peptide were performed using scanning tunneling spectroscopy (STS). The molecules were trapped between the gold tip and the substrate using a Au-S linkage. The electron transfer behavior of the peptide was examined as a function of the tip-substrate distance at fixed bias voltage and as a function of bias voltage at a fixed distance between the tip and the substrate. The data obtained from these experiments indicated that the electron transfer through alpha-helical peptide is very efficient, and its conductivity is comparable to those observed for dodecanedithiol. There is also a directional dependence of electron transmission through the peptide, which is connected with the electric field generated by the molecular dipole of the helix.     

The Set of Measures Given by Bounded Solutions of the Complex Monge-Ampere Equation on Compact Kahler Manifolds

Consider the image of the Monge–Ampère operatoracting on bounded functions, defined on a compact Kählermanifold, whose sum with the local Kähler potential isplurisubharmonic. It is shown that a nonnegative Borel measurebelongs to this image if and only if it belongs to the imagelocally. In particular, those measures form a convex set.     

Poly(vinyl methyl ether) hydrogels at temperatures below the freezing point of water—molecular interactions and states of water

Water interacting with a polymer reveals a number of properties very different to bulk water. These interactions lead to the redistribution of hydrogen bonds in water. It results in modification of thermodynamic properties of water and the molecular dynamics of water. That kind of water is particularly well observable at temperatures below the freezing point of water, when the bulk water crystallizes. In this work, we determine the amount of water bound to the polymer and of the so-called pre-melting water in poly(vinyl methyl ether) hydrogels with the use of Raman spectroscopy, dielectric spectroscopy, and calorimetry. This analysis allows us to compare various physical properties of the bulk and the pre-melting water. We also postulate the molecular mechanism responsible for the pre-melting of part of water in poly(vinyl methyl ether) hydrogels. We suggest that above ?60 °C, the first segmental motions of the polymer chain are activated, which trigger the process of the pre-melting.     

The smooth cohomology ofN=2 supersymmetric Landau-Ginzburg field theories

We compute the smooth cohomology (both unrestricted and compactly supported) of the supercharge of an ultraviolet cutoffN=2 supersymmetric Landau-Ginzburg field theory.Supported in part by the National Science Foundation under grant DMS-9206936.Supported in part by the Department of Energy under grant DE-FG02-88ER25065.     

Delinearization of quantum logic

The algebraic structure of the set of elementary observables of a delinearized quantal theory is described. As the delinearization procedure provides a kind of classical representation for any quantal theory, its relation to the traditional hypothesis of hidden variables is discussed.