Materials Literature
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Abstract A new method of rolling with side constraints was applied to polyethylene. The process relies on the rolling of a material inside a channel formed on the circumference of one roll with another roll having a thickness matching the width of the channel in the first roll. The rolling inside a channel resembles t…
Abstract We investigated the possibility of obtaining high‐density polyethylene (PE) samples with crystals in a broad range of thicknesses. PE samples solidified by slow cooling were subjected to hydrostatic pressure at room temperature and then heated to the region of mobile pseudohexagonal form, without being passed…
Abstract The influence of crystallization conditions on the morphology of the contact layer of high‐density polyethylene crystallized on graphite has been investigated. The characteristic morphology of the polyethylene contact layer consists of striated, ribbonlike structures organized in domains in which the striatio…
Abstract The mechanical behavior of oriented bars of polyethylene obtained by heavy rolling with side constraints was studied. The bars were rolled to a permanent deformation ratio (DR) of up to 8.3. The elastic modulus and ultimate strength measured along the rolling direction increase with increasing DR. For samples…
We demonstrated for the first time the thermo-mechanical processing of the organogels of dibutyllauroyl glutamide as a small molecule gelling agent (SMGA) in a biocompatible solvent, isostearyl alcohol. The study focused on the impact of novel thermomechanical processing parameters such as temperature, strain, and the…
The spin-polarization patterns of a weakly coupled triplet−doublet spin pair are studied in a covalently linked copper (II)−free base porphyrin dimer partially oriented in a liquid crystalline solvent. The triplet−doublet pair is generated in the dimer by either spin−orbit intersystem crossing (ISC) within the free-ba…
The identity of reactive intermediates and of active sites and the details of redox cycles and oxygen removal pathways during NO decomposition on well-characterized Cu−ZSM5 were examined by combining previous spectroscopic and steady-state kinetic studies with measurements of the rate of evolution of NO, N 2 O, NO 2,…
Abstract The crystallization of polymer films in a temperature gradient was simulated. The curvature of lamella growth directions observed experimentally was taken into account. The computer simulation permitted the visualization of the evolution of the spherulitic pattern and also the calculation of the conversion of…
We report a detailed experimental study of the aging of the (initial) random hexagonal close-packed (rhcp) crystals formed in suspensions of hard-sphere colloids near the melting point. By suspending the same colloidal particles in two different mixtures of solvents we are able to tune the strength of the gravitationa…
[structure: see text] Oligothienyl-substituted paracyclophanes bearing alpha-thienyl substituents, which block polymerization at these sites, undergo oxidation to form stable radical cations and dications. Splitting of the first voltammetric oxidation wave of stacked dimers into two single-electron processes correspon…
Diamond is impressive because of its wide range of extreme properties. By most measures, diamond is ‘the biggest and best’: it is the hardest known material, has the lowest coefficient of thermal expansion, is chemically inert and wear resistant, offers low friction, has high thermal conductivity, and is electrically…
The switching behavior of 1,2-bis(5-phenyl-2-methylthien-3-yl)cyclopentene is studied by means of polarization selective nonlinear optical spectroscopy and time-dependent density functional theory. The combined information from the observed population and orientational dynamics together with the results of theoretical…
Abstract The effect of thermal treatment on the crystalline and supermolecular structure of polylactide was investigated. The samples were isothermally crystallized by two methods, the crystallization temperature being reached (1) via cooling from the melt and (2) via heating from the glassy, amorphous state. The samp…
Abstract New bisphenol monomers, (3‐methyl)phenylhydroquinone and (3‐trifluoromethyl)phenylhydroquinone, were prepared in a two‐step synthesis. A series of poly(aryl ether ketone)s were derived from these bisphenols via a nucleophilic aromatic substitution polycondensation with various bisfluoro compounds. The polycon…
Three-dimensionally ordered mesoporous niobium oxide was prepared by a neutral templating route with the addition of a trace amount of cations, which have 5- and 2-nm pore diameter and wall thickness, respectively.
Abstract We have been investigating the synthesis of quantum dots of CdSe, CuInS 2 , and CuInSe 2 for use in an intermediate bandgap solar cell. We have prepared a variety of quantum dots, using the typical organometallic synthesis routes pioneered by Bawendi et al. in the early 1990s. However, unlike previous work in…
We develop a general theory of electron--hole recombination in organic light emitting diodes that leads to formation of emissive singlet excitons and nonemissive triplet excitons. We briefly review other existing theories and show how our approach is substantively different from these theories. Using an exact time-dep…
The effect that an additional energy barrier E_{kr} for step adatoms moving around kinks has on equilibrium step edge fluctuations is explored using scaling arguments and kinetic Monte Carlo simulations. When mass transport is through step edge diffusion, the time correlation function of the step fluctuations behaves…
The Hall resistivity, magnetoresistance, and magnetization of La_{1-x}Ca_{x}CoO_{3} epitaxial films with x between 0.25 and 0.4 grown on lanthanum aluminate were measured in fields up to 7 T. The x=1/3 film, shows a reentrant metal insulator transition. Below 100 K, the x=1/3 and 0.4 films have significant coercivity…
Human malaria, one of the most striking, reemerging infectious diseases, is caused by several types of Plasmodium parasites. As the parasite digests hemoglobin in human red blood cells, the heme byproduct crystallizes into micron-sized malaria-pigment (hemozoin). Making use of a recently reported powder-crystal struct…