Materials Literature
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Study on the molecular packing of the α-form of poly( l -lactide) has been attempted taking into account packing energy calculations, refinement against new electron diffraction data, and Monte Carlo simulations. Packing energy has been evaluated for a fixed 10 7 conformation and an antiparallel arrangement of molecul…
Using the spin-polarized tunneling model and taking into account the basic physics of ferromagnetic semiconductors, we study the temperature dependence of the tunneling magnetoresistance (TMR) in the diluted magnetic semiconductor (DMS) trilayer heterostructure system (Ga,Mn)As/AlAs/(Ga,Mn)As. The experimentally obser…
We present a class of discrete Schrödinger operators, with potentials derived from nonprimitive substitutions, that has purely singular continuous spectrum. We give sufficient conditions on the substitution rule assuring singular continuous spectrum, either for a generic set in the hull of the potential or for a set o…
Abstract A low molecular weight prepolymer with reactive end groups was annealed at temperatures between 200 and 245°C to obtain kinetic parameters for solid‐state polymerization of poly(ethylene naphthalate) (PEN). An equation was developed to describe the relationships among time, temperature, and final molecular we…
When a liquid sheet is subject to vertical vibration, parametric instabilities may occur and give rise to standing waves. The present work develops the linear theory of this phenomenon for inviscid, Newtonian and viscoelastic liquids. Floquet theory is applied to the governing equations to obtain recursion relations f…
Abstract The graft copolymerization of N ‐vinyl pyrrolidone ( N ‐VP) onto cellulose was carried out with a cobalt acetylacetonate complex Co(acac) 3 as an initiator under a nitrogen atmosphere at 50 ± 0.1°C. The graft yield percentage (% G ) obtained as a function of the concentrations of N ‐VP and Co(acac) 3 and the…
Abstract N ‐hexenyl side branches were introduced into poly(butylene succinate) (PBS) by polymerization of succinic acid (SA) with 1,4‐butanediol (BD) in the presence of 7‐octene‐1,2‐diol (OD). Thermal properties and biodegradability of the aliphatic polyesters were investigated before and after epoxidation of the pen…
As a model of the core of molecules forming liquid crystals, the molecular structure of phenyl benzoate (Ph-C(=O)-O-Ph) at 409 K was determined by gas electron diffraction, and the relationship between the gas-phase structures of model compounds and the nematic-to-liquid transition temperatures was studied. Structural…
Abstract Regenerated Antheraea pernyi silk fibroin films prepared from calcium nitrate solution were treated with heat for crystallization. The structural and conformational changes caused by heat treatment were investigated with X‐ray diffraction, infrared spectroscopy, and differential scanning calorimetry. The temp…
Abstract Poly(β‐hydroxybutyrate) (PHB) is a bacteria storage biodegradable polyester that is considered to be a natural substitute for synthetic thermoplastics in many applications. However, brittleness hampers its utility. This study shows that oriented elastic fibers of PHB with favorable mechanical properties (360‐…
The synthesis, structure, and physical characterization of two new radical salts formed with the organic donor bis(ethylenethia)tetrathiafulvalene (BET-TTF) and the octahedral anions hexacyanoferrate(III), [Fe(CN)(6)](3-), and nitroprusside, [Fe(CN)(5)NO](2-), are reported. These salts are (BET-TTF)(4)(NEt(4))(2)[Fe(C…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTOne-Electron Reduction of an Antiferromagnetically Coupled Triradical Yields a Mixed-Valent Biradical with Enhanced Ferromagnetic CouplingDavid A. Shultz and R. Krishna KumarView Author Information Department of Chemistry North Carolina State University Raleigh, North…
Abstract p ‐Phenylenediamine was chemically attached to low molecular weight chlorinated paraffin wax. The polymer‐bound p ‐phenylenediamine was characterized by vapor‐phase osmometry (VPO), proton magnetic resonance spectroscopy ( 1 H‐NMR), infrared spectroscopy (IR), and thermogravimetric analysis (TGA). The efficie…
The interaction of a hydroxyl radical with cluster models of a hydroxylated α-quartz surface was studied by means of density functional calculations. Two molecular models representing isolated (⋮Si OH) and geminal ( Si(OH) 2 ) silanol-terminated quartz surfaces were used. Two reactive sites of the silanol models were…
The shear dependent location of the isotropic-nematic spinodals in suspensions of bacteriophage fd is studied by means of time resolved birefringence experiments. The hysteresis in the birefringence on increasing and subsequently decreasing the shear-rate allows the determination of the location of points in the shear…
The valence band and $\mathrm{C}1s$ photoemission spectra were measured from the tips and the sidewalls of multiwalled carbon nantoubes grown on Si substrates. The results show an overall spectral shift to the higher-binding-energy side, a larger density of states at the Fermi level, and a lower work function at the t…
RuO 2 (110) surfaces were prepared by exposing Ru(0001) to 107 L of O2 at 700 K. Postexposure of O2 at 300 K resulted in an additional oxygen species (O-cus) adsorbed on coordinatively unsaturated Ru atoms (Ru-cus). The surface was then exposed to CO at 300 K and studied by thermal desorption spectroscopy (TDS) and hi…
First hyperpolarizabilities β were obtained for CX4 molecules in gas and liquid phases from hyper-Rayleigh scattering measurements at λ=1064 nm. The gas-phase results for βxyz (atomic units) are 7.1±0.9 (CH4), 7.0±0.9 (CD4), 5.4±0.6 (CF4), and 11.0±0.9 (CCl4). Ab initio calculations of β are consistent with the experi…
To determine the factors affecting the ground-state electron configuration of low-spin Fe(III) porphyrin complexes, we have examined the (1)H NMR, (13)C NMR, and EPR spectra of a series of low-spin bis-ligated Fe(III) porphyrin complexes [Fe(Por)L(2)](+/-), in which the positions of porphyrin substituents and the coor…
Abstract Blend films were prepared from hydrophobic poly( L ‐lactide) (PLLA) and hydrophilic poly(vinyl alcohol) (PVA) with different PLLA contents [ X PLLA (w/w) = PLLA/(PVA + PLLA)] by solution casting and melt quenching. Their morphology, swelling behavior, and surface and bulk properties were investigated. Polariz…