Materials Literature
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Hydrogen bonds between urea units allow self-organization of π systems in mono- and bithiophenes into fibers as shown schematically. In these fibers there is a surprisingly high mobility of charge carriers as determined by pulse-radiolysis time-resolved microwave conductivity measurements.
Electromigration in 0.15–10 μm wide and 0.3 μm thick Cu lines deposited by physical vapor deposition has been investigated using both resistance and edge displacement techniques in the sample temperature range 255–405 °C. For wide polycrystalline lines (>1 μm), the dominant diffusion mechanism is a mixture of g…
By the attachment of interacting laser dyes to the chain ends and focal point of a dendritic macromolecule it is possible to funnel energy harvested by the large peripheral antenna of the dendrimer (see picture on the left) efficiently and directly to the central fluorescent core (picture in the middle) by a process t…
To understand the near-interface magnetism in manganites, ultrathin films of La0.67Sr0.33MnO3 were grown epitaxially on single-crystal (001) LaAlO3 and (110) NdGaO3 substrates. The temperature and magnetic field-dependent film resistance is used to probe the film’s structural and magnetic properties. A surface and/or…
Thin films of quantum size ZnO particles were fabricated by electrophoretic deposition from stable colloidal suspensions. The average particle size and hence the optical properties can be tailored by controlling the aging time and temperature of the suspensions. Thin films prepared by electrophoretic deposition exhibi…
The solvent-free, catalyst-free condensation of pyrrole and aldehydes provides an extremely facile synthetic pathway to novel corroles [Eq. (1); Ar=C6F5, 2,6-F2C6H3, 2,6-Cl2C6H3]. The product containing pentafluorophenyl groups is an excellent precursor of other derivatives, including an ionic, water-soluble corrole.
Although progress has been made in the ab initio simulation of lattice dynamics in semiconducting crystals, information about the relaxation of nonequilibrium lattice vibrations remains incomplete. This work studies the relaxation times of room-temperature thermal phonons through measurements of thermal conduction alo…
Optical birefringence measurements are used to characterize how the molecular order of spider (Nephila clavipes) major ampullate silk is affected by linear spinning rate, by the extent of post-spin drawing, and by post-spin drawing rate. Results are interpreted qualitatively in terms of a simple microstructural model,…
An aliphatic/aromatic polyester blend has been dealt with in this study. As an aliphatic polyester, poly(butylene succinate) (PBS) was used, which is thought to possess biodegradability, but it is relatively expensive. It has been blended with poly(butylene terephthalate) (PBT) in order to obtain a biodegradable blend…
The interactions between soluble collagen (C) from calf skin and poly(acrylic acid) (PAA) were studied. Mixing aqueous solutions of collagen and PAA, at various pH values (2.5–4), leads to the formation of complexes that precipitate in the form of insoluble aggregates. The effects of mixture composition, pH, and ionic…
Using first principles density functional calculations, gold monatomic wires are found to exhibit a zigzag shape which remains under tension, becoming linear just before breaking. At room temperature they are found to spin, what explains the extremely long apparent interatomic distances shown by electron microscopy.Th…
The temperature dependence of the elastic stiffness constant c 55 in [N(CH 3 ) 4 ] 2 ZnBr 4 single crystals has been measured using Brillouin scattering and the ultrasonic pulse echo overlap technique. The elastic constant c 55 was found to soften strongly in both the paraelastic and ferroelastic phases. Despite the f…
A new process for producing polyamide from polyester and diamine was proposed. An attempt was made to produce polyamide 6T from polyethyleneterephthalate or dimethylterephthalate with hexamethylenediamine in water, o-dichlorobenzene and sulfolane. Characterization of the products by IR, elemental analysis, solution vi…
Oligomers covering degrees of polymerization up to 23 of 2-(1-imidazolyl)ethyl methacrylate (ImEMA) were synthesized by group transfer polymerization (GTP) in propylene carbonate and tetrahydrofuran (THF). While GTP proceeds smoothly in propylene carbonate, polymerization in THF is accompanied by oligomer precipitatio…
X-ray resonant scattering, due to the anisotropic tensor of susceptibility (ATS), from magnetite, Fe 3 O 4 , near the Fe K-absorption edge, was measured from room temperature to 80 K. The energy dependence of the 002 “forbidden” reflection intensity showed two sharp peaks just above and below the edge. The azimuthal d…
This paper describes the concepts of resolution in the time and temperature domains and illustrates the principles using two new sample controlled thermal analysis (SCTA) techniques. The use of SCTA, where the sample temperature is determined by the rate of reaction, offers a number of advantages over conventional (li…
We have developed an algorithm to analyze the circular dichroism of proteins for secondary structure. Its hallmark is tremendous flexibility in creating the basis set, and it also combines the ideas of many previous workers. We also present a new basis set containing the CD spectra of 22 proteins with secondary struct…
A model system involving a polyanionic alginic acid (AA) overlayer ionically immobilized on a polycationic polyethyleneimine underlayer, in turn linked to plasma oxidized polystyrene, was used to investigate the relationship between surface structure properties and resistance to cell adhesion. X-ray Photoelectron Spec…
This letter presents the equation of capillary hydrodynamics for interfaces between viscous isotropic fluids and nematic liquid crystals (NLCs) to establish the existence of a new class of Marangoni flow. The interfacial stress balance equation involves the surface divergence of the surface stress tensor. It is shown…
2,2,′3,3′-Biphenyltetracarboxylic dianhydride (2,2,′3,3′-BPDA) was prepared by a coupling reaction of dimethyl 3-iodophthalate. The X-ray single-crystal structure determination showed that this dianhydride had a bent and noncopolanar structure, presenting a striking contrast to its isomer, 3,3,′4,4′-BPDA. This dianhyd…