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。
A series of dimeric through octameric (1→5) amide-linked sialooligomers were prepared using solid-phase peptide methods on Rink resin with Fmoc protecting group chemistry. The oligomers were conjugated to ε-amino caproic acid in order to model membrane-bound conformations. The secondary structure of the oliogomers was…
We consider the variation in miscibility during a polycondensation reaction which forms a random multiblock copolymer. Taking a “Markov chain” model for the reacting polymer system, we apply the random phase approximation and calculate the spinodal as a function of degree of reaction. In order to achieve this, we deve…
An attempt has been made to understand the mechanism of ionic conductivity in polyphosphazene−salt complexes by the synthesis and study of systems with crown ether side groups and salts with different cations. Amorphous phosphazene polymers, bearing either (12-crown-4)-methoxy, (15-crown-5)-methoxy, or (18-crown-6)-me…
A hyperbranched polyfluorinated benzyl ether polymer was prepared from the A 2 B monomer 3,5-bis[(pentafluorobenzyl)oxy]benzyl alcohol. The polymerization was based upon deprotonation of the benzylic alcohol (B), followed by nucleophilic substitution of the p -fluorines of the two pentafluorophenyl (A) groups to form…
Histogram reweighting Monte Carlo simulations were used to obtain polymer/solvent phase diagrams for lattice homopolymers of chain lengths up to r = 1000 monomers. The simulation technique was based on performing a series of grand canonical Monte Carlo calculations for a small number of state points and combining the…
We comment some recent unexpected experimental results on proton/deuteron deep inelastic scattering off water molecules in H2O-D2O mixtures (C.A. Chatzidimitrou-Dreismann et al. Phys. Rev. Lett. 79, 2839 (1997)) where a strong dependence of the ratio of proton/deuteron cross sections on the composition of the mixture…
A Fourier transform infrared (FT-IR) spectrometer equipped with a microscopic accessory was used to monitor the cellulose crystalline structure at each developmental stage of coniferous tracheid cell wall formation. The spectra showed that the cellulose in the primary cell wall was rich in the metastable I α crystalli…
Use of amphiphilic triblock copolymers to direct the organization of polymerizing silica species has resulted in the preparation of well-ordered hexagonal mesoporous silica structures (SBA-15) with uniform pore sizes up to approximately 300 angstroms. The SBA-15 materials are synthesized in acidic media to produce hig…
Density and viscosity of 0.25[xKSCN + (1 − x )NaSCN] + 0.75CH 3 CONH 2 melt systems were measured as functions of temperature (293.15 ≤ T /K ≤ 343.15) and mole fraction, x = 0.0 to 1.0. The temperature dependence of viscosity has been analyzed by using the Vogel−Tammann−Fulcher (VTF) equation. Molar volumes and intrin…
Aerial oxidation of Mn(II)/ptt(3)(-) (ptt(3)(-) = propane-1,2,3-trithiolate) mixtures gives [Mn(2)(pttd)(2)](2)(-), where pttd(4)(-) is the mono(disulfide) of ptt(3)(-). (NEt(3)Bz)(2)[Mn(2)(pttd)(2)] (2) crystallizes in space group P2(1)/c with (at -158 degrees C) a = 11.540(2) Å, b = 12.115(2) Å, c = 17.478(4) Å, bet…
The interfacial properties of a three-component, two-phase A/B:C blend are investigated to understand the effect of the A and B chain lengths on the interfacial excess of B, z B *, the interfacial tension, γ ABC, and the interfacial width, w ABC . The A/B:C components are polystyrene/poly( d 8 -styrene- co -4-bromosty…
Beer's law and linear superposition of absorption spectra are known to be valid in dilute solutions. In this work it is shown with two examples that in a condensed phase conducting polymers are subject to the frequency-dependent local field of lightwave, also called dielectric effect, which influences the absorbance,…
The possibility of fabricating thermoelectric coolers using thin film deposition and micromachining is investigated. The processing sequences described facilitate fabrication of the thermoelectric cooler and electronic components, such as laser diodes, CCD and infrared detectors, as elements of an integrated circuit.…
An organic trialdehyde, TRIPOD (2), was designed as a template for the synthesis of a three-helix bundle protein. Crystallographic data indicate that the aldehyde groups are appropriately spaced to maximize hydrophobic interactions between the chains of the protein. Peptide strands were attached to the template by red…
This paper explores the copolymerization of l -lactide ( l -LA) with 2,2-[2-pentene-1,5-diyl]trimethylene carbonate ( c HTC). Since c HTC has a cyclohexene group, this provided a route for preparing poly(lactic acid), (PLA), based chains decorated with controlled quantities of C C substituents. Ring-opening copolymeri…
The syntheses and fluid-solution EPR spectra of nitroxide-substituted porphyrins 1-3 are described. The phenylnitroxide is attached to the meso-position of three porphyrins: (a) directly through a single bond (1); (b) through an ethenyl group (2); and (c) through an ethynyl group (3). The spin distribution in each of…
The luminescence properties of Eu 3+ encapsulated in sol−gel-derived optically transparent silica gels were investigated by time-resolved laser spectroscopy. At the xerogel stage, the emission spectra originated mainly from Eu 2+ at 410 nm, and only a small contribution from Eu 3+ at 580 nm and electron−hole (e - −h +…
Quasicrystals are materials of both intellectual and practical importance. Although some level of understanding can now be applied to their bulk electronic and atomic structure, the same cannot be said of their surface properties. In this article, we point out some of the key issues in the surface science of quasicrys…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTSynthesis of the First Organic Polymer/Polyphosphazene Block Copolymers: Ambient Temperature Synthesis of Triblock Poly(Phosphazene−ethylene oxide) CopolymersJames M. Nelson, A. Paul Primrose, Thomas J. Hartle, Harry R. Allcock, and…
The orientation of the principal axes of the g tensor with respect to the relationship of axial ligand planes to the porphyrin nitrogens has been studied in the framework of the one-electron crystal field model for tetragonal and rhombic low-spin d 5 complexes such as ferriheme centers. All five d atomic orbitals were…