Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Polyurethane (PU) elastomers from castor oil based polyol, polyethylene glycol (PEG) of various molecular weight (200, 400, and 600) and toluene diisocyanate were prepared in the form of transparent sheets. The sorption, mechanical and thermal properties have been studied. The solubility parameter, molecular weight be…
Abstract The synthesis of the new chromophores 2‐{4‐[4‐( N , N ‐dihydroxyethylamino)‐phenylazo]‐phenyl}‐6‐nitrobenzoxazole ( 1 ) and 4‐[4‐( N , N ‐dihydroxyethylamino)phenylazo]‐benzoic acid ( 2 ) is described. Three homopolymers obtained by the polycondensation of 1 with propyloxy‐terephthalic acid and 1 and 2 with 2…
The effects of woven structures on fluid flow through the basic weaves of multifilament woven filter cloths were studied numerically by using the fluid-flow software fluent™. From results of the numerical solution, the flow pattern and the resistance to flow in the interstices were obtained. Results of this work show…
New supramolecular A2B2 co-polymers formed in solution from a rigid diporphyrin monomer (the A2 unit) and a short flexible dipyridine monomer (the B2 unit) are reported; NMR experiments show that complete binding occurs at mM concentrations; UV titrations reveal that the dipyridine unit and a monomeric control ligand…
Core level photoemission spectra from a free-standing bundle of single-wall carbon nanotubes have been measured using a high-flux soft x-ray spectromicroscope. The good signal-to-noise ratio for the C 1s emission provides information on fundamental quantities such as the core-hole lifetime and binding energy, free fro…
We grow multiwall carbon nanotube (CNT) films using thermal chemical vapor deposition at atmospheric pressure using a mixture of acetylene and nitrogen from a 4-nm-thick Ni film catalyst. CNTs are characterized using electron microscopy and Rutherford backscattering spectrometry. CNTs grown with this method are extrem…
The interaction of q = 0 delta- and lambda-Tb and Eu complexes with poly(dAdT), poly(dGdC) and calf-thymus DNA has been examined by absorption, emission and chiroptical spectroscopy and is sensitive to complex helicity, base-pair type and the nature of the lanthanide excited state.
The first attempt is undertaken to consider systematically topological structures of zirconosilicates and their analogs (60 minerals and 34 synthetic phases), where the simplest structure units are MO(6) octahedra and TO(4) tetrahedra united by vertices ([TO(4)]:[MO(6)] = 1:1-6:1). A method of analysis and classificat…
Brief treatment of azuliporphyrins 5 with nickel(II) or palladium(II) acetate in refluxing DMF afforded excellent yields of the related chelates; these novel organometallic compounds retain cross-conjugated borderline aromatic structures as judged by UV-Vis and NMR spectroscopy, and X-ray crystallography.
An efficient algorithm for hydrodynamical interaction of many deformable drops subject to shear flow at small Reynolds numbers with triply periodic boundaries is developed. The algorithm, at each time step, is a hybrid of boundary-integral and economical multipole techniques, and scales practically linearly with the n…
New L-lysine derivatives with a positively charged terminal can gel water below 1 wt%; particularly, 1a and 2a form a hydrogel at 0.3 wt% corresponding to approximately 12,300 and 12,500 waters/gelator molecule, respectively.
The thermal conductivities \ensuremath{\kappa} of high-density amorphous (HDA) ice and low-density amorphous (LDA) ice were measured under pressure. The results for HDA show typical glasslike behavior, i.e., positive $d\ensuremath{\kappa}/dT,$ whereas LDA exhibits crystal-like behavior, indicating that phonon-phonon s…
A unique negative lateral shift is demonstrated in this letter for a Gaussian beam reflected from a grounded slab with both negative permittivity and permeability, which is distinctly different from a shift caused by a regular grounded slab. The incident beam is modeled as a tapered wave with a Gaussian spectrum. The…
We report the first investigation of the photo-response of the conductivity of a new class of organic semiconductors based on functionalized pentacene. These materials form high quality single crystals that exhibit a thermally activated resistivity. Unlike pure pentacene, the functionalized derivatives are readily sol…
The anchoring of nematic liquid crystals on surfaces with grafted liquid crystalline chain molecules is studied by computer simulations and within a mean field approach. The computer simulations show that a swollen layer of collectively tilted chains may induce untilted homeotropic (perpendicular) alignment in the nem…
The meander instability of a vicinal surface growing under step flow conditions is studied within a solid-on-solid model. In the absence of edge diffusion the selected meander wavelength agrees quantitatively with the continuum linear stability analysis of Bales and Zangwill [Phys. Rev. B {\bf 41}, 4400 (1990)]. In th…
Silver Schottky contacts were fabricated on (112̄0) n-ZnO epilayers, which were grown on R-plane sapphire substrates by metalorganic chemical-vapor deposition. The flatband barrier height was determined to be 0.89 and 0.92 eV by current–voltage and capacitance–voltage measurements, respectively. The ideality factor wa…
Rietveld neutron powder profile analysis of the compound Na(0.5)Bi(0.5)TiO(3) (NBT) is reported over the temperature range 5-873 K. The sequence of phase transitions from the high-temperature prototypic cubic structure (above 813 K), to one of tetragonal (673-773 K) and then rhombohedral structures (5-528 K) has been…
There has been much recent interest in a so-called “giant-dielectric phenomenon” displayed by an unusual cubic perovskite-type material, CaCu3Ti4O12; however, the origin of the high permittivity has been unclear [M. A. Subramanian, L. Dong, N. Duan, B. A. Reisner, and A. W. Sleight, J. Solid State Chem. 151, 323 (2000…
The architecture of an engineered tissue substitute plays an important role in modulating tissue growth. A novel poly(D,L-lactide-co-glycolide) (PLGA) structure with a unique architecture produced by an electrospinning process has been developed for tissue-engineering applications. Electrospinning is a process whereby…