Materials Literature
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The potential energy surfaces of several model atomic glass formers have been studied using eigenvector-following techniques. Barrier distributions, cooperativity indices, path lengths, and vibrational densities of states (VDOS) are presented based upon data sets containing more than 250 000 pathways in total. We find…
We have fabricated multiwalled carbon nanotubes (CNTs) with flowing acetylene, using a well-ordered porous anodic aluminum oxide (AAO) nanotemplate with or without deposition of Co in the pores as a catalyst. Without deposition of Co, the tubes were made in the pores having the shape of the pores by catalysis with the…
Magnetoresistive effects $(R(0)\ensuremath{-}R(H))/R(H)$ exceeding $500%$ are found at room temperature in a field of 7 mT in nanocontacts between ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ crystallites. The shape of the $I(V)$ curve depends on field and the magnitude of the magnetoresistance is correlated with the resistanc…
We report measurements of the transport and the magnetic properties of high-quality, sub-millimeter-sized MgB2 single crystals with clear hexagonal-plate shapes. The low-field magnetization and the magnetic hysteresis curves show the vortex pinning of these crystals to be very weak. The Debye temperature of $Θ_{D}\sim…
Abstract A model polyethylene‐poly( L ‐lactide) diblock copolymer (PE‐ b ‐PLLA) was synthesized using hydroxyl‐terminated PE (PE‐OH) as a macroinitiator for the ring‐opening polymerization of L ‐lactide. Binary blends, which contained poly( L ‐lactide) (PLLA) and very low‐density polyethylene (LDPE), and ternary blend…
Density functional theory (DFT) electronic structure calculations were carried out to predict the structures and ground-state spectra for zinc complexes of porphyrin (ZnP), tetraazaporphyrin (ZnTAP), tetrabenzoporphyrin (ZnTBP), and phthalocyanine (ZnPc). All four porphyrins are found to have stable D4h structures. St…
We used near-edge x-ray absorption fine structure (NEXAFS) spectroscopy to link the orientational bond order at three carbonaceous surfaces-rubbed polyimide, ion beam-irradiated polyimide, and ion beam-irradiated diamondlike carbon films-with the direction of liquid crystal (LC) alignment on these surfaces. We show th…
We have observed very large tunneling magnetoresistance (TMR) in epitaxially grown ${\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{As}/\mathrm{AlAs}/{\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{As}$ ferromagnetic semiconductor tunnel junctions. Large TMR ratios more than $70%$ (maximum $75%$) wer…
The discovery of periodic mesoporous MCM-41 and related molecular sieves has attracted significant attention from a fundamental as well as applied perspective. They possess well-defined cylindrical/hexagonal mesopores with a simple geometry, tailored pore size, and reproducible surface properties. Hence, there is an e…
Central to the concept of seed-mediated growth of nanoparticles is that small nanoparticle seeds serve as nucleation centers to grow nanoparticles to a desired size. We have examined this common assumption in a model system, the wet chemical synthesis of gold nanoparticles via reduction of a gold salt, by transmission…
The structure of the free-acid form of the coenzyme NAD(+) was determined at 100 K from a single-crystal neutron experiment. NAD(+) is the oxidized form of the coenzyme redox pair NAD(+)/NADH and plays an important role in the catalysis of biological processes. The molecule crystallizes in space group P1 with one NAD(…
The potassium salt of poly(trimethylene-1,1-dicarboxylic acid), the first member of a new polyelectrolyte family where the carbon backbone is substituted on every third carbon by two carboxylate anions, was obtained by hydrolysis of a monodisperse di- n -propyl ester polymer (CH 2 CH 2 C(COO n Pr) 2 ) n . This precurs…
Two poly(pyridinium salt)s containing tosylate as a counterion were synthesized by the ring-transmutation polymerization reaction of bis(pyrylium tosylate) with the corresponding aromatic diamines and characterized for their lyotropic liquid-crystalline as well as fluorescence properties in both polar protic and aprot…
The preparation of derivatives by the traditional methods of soaking is one of the most time-consuming steps in protein crystal structure solution by X-ray diffraction techniques. The 'quick cryosoaking' procedure for derivatization with halides (monovalent anions) offers the possibility of significantly speeding up t…
We have examined the forces of interaction between opposing polystyrene brushes of various molecular weights in cyclohexane near the ϑ temperature. The force−distance profiles and structural information obtained from surface forces experiments are compared to those of brushes in the good solvent, toluene. In both solv…
Rare-earth alloys $R{\mathrm{Ag}}_{1\ensuremath{-}x}{\mathrm{In}}_{x}$ (where $R=\mathrm{La},$ Ce, and Pr) are improper ferroelastic materials with the CsCl structure. A weakly first-order phase transition occurs with the softening of a zone-edge ${\mathrm{M}}_{5}^{\ensuremath{-}}$ mode that drives the material from a…
Summary Using four different wood species, the wetting behaviour of sanded wood surfaces was compared with that of microtomed surfaces. Sanding caused lower contact angles and lower total surface free energies. Electron donor components were considered to be responsible for the observed changes according to the applie…
We examine the demixing transition in star-polymer-colloid mixtures for star arm numbers f=2,6,16,32 and different star-polymer-colloid size ratios 0.18< or =q< or =0.50. Theoretically, we solve the thermodynamically self-consistent Rogers-Young integral equations for binary mixtures using three effective pair potenti…
A systematic measurement of thermal conductivity $\ensuremath{\kappa}(T)$ below room temperature has been carried out on a series of single-crystal samples of ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ that were chosen to probe changes on crossing several crystallographic phases and electron…
The ferromagnetic Kondo lattice model with an antiferromagnetic interaction between localized spins is a minimal description of the competing kinetic (t) and magnetic (K) energy terms which generate the rich physics of manganite systems. Motivated by the discovery in one dimension of homogeneous ``island phases,'' we…