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。
Twenty-six fluoro-substituted 4-n-alkoxyphenyl 4′-n-alkyi-and 4′-n-alkoxybiphenyl-4-carboxylates are reported. The number and position of the fluoro groups influences the liquid crystal phase sequence and has a dramatic effect on the liquid crystal transition temperatures. Some compounds have low melting points and a…
ß-D,L,-Butyrolactone was polymerized at 50°C in deuterated solvents of different polarity, and both the conversion and the formation of crotonate groups were directly determined from the reaction mixture by means of 1 H-NMR spectroscopy. Two classes of initiators, namely nonionic ones, such as tertiary amines or triph…
Abstract We derive and analyze a model for sharp fronts in glassy polymers. We take the major effect of a diffusing penetrant on the polymer entanglement network to be the inducement of a differential viscoelastic stress. This couples diffusive and mechanical processes through a viscoelastic response where the strain…
A versatile instrument for glancing-angle x-ray absorption spectroscopy (XAS) and x-ray reflectivity in routine use on the Daresbury Synchrotron Radiation Source is described. This facility can be used for XAS measurements in both reflectivity and fluorescence modes as well as for qualitative studies of angular depend…
Abstract A series of the wholly aromatic polyazomethines (PAM) having flexible side chains was synthesized by solution and melt polycondensation of 2,5‐dialkoxyterephthalaldehydes and aromatic diamines. The solution polycondensation was carried out at 80°C for 24 h in 1,3‐dimethyl‐3,4,5,6‐tetrahydro‐2(1 H )‐pyrimidino…
Thermophilic lactate dehydrogenases from Thermotoga maritima and Bacillus stearothermophilus are stable up to temperature limits close to the optimum growth temperature of their parent organisms. Their catalytic properties are anomalous in that Km shows a drastic increase with increasing temperature. At low temperatur…
An experimental station with a four-circle diffractometer combined with tunable and focusing optics was designed and constructed for x-ray crystallography using synchrotron radiation from the vertical wiggler at the Photon Factory. The optics implemented into beamline 14A comprises a double-crystal monochromator and a…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCarbon K-shell excitation of metallocenesE. Ruehl and A. P. HitchcockCite this: J. Am. Chem. Soc. 1989, 111, 14, 5069–5075Publication Date (Print):July 1, 1989Publication History Published online1 May 2002Published inissue 1 July 1989https://pubs.acs.org/doi/10.1021/ja00196a…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTConductive molecular crystals from three-dimensional building blocks: synthesis and characterization of tris(bis(ethylenedithio)tetrathiafulvalenium) bis(tris(2-thioxo-1,3-dithiole-4,5-dithiolato)vanadate), [ET]3[V(dmit)3]2, and the corresponding tetramethyltetraselenafulval…
Discontinuous (first-order) anchoring transitions are shown to occur as a function of water adsorption at the nematic-liquid-crystal(E9)--gypsum and E9-mica interfaces. The transitions involve growth of domains with an anchoring a' making a finite angle with the direction a of the parent anchoring. The growth proceeds…
An analysis of the geometry of binding of metal ions by cysteine and methionine residues in protein structures has been made by using the Protein Data Bank. Metal ions have a distinct model of binding to each of these residues, and this is independent of the nature of the metal center or the type of protein. Metal ion…
A polar (PCH-5) and a non-polar (152) compound are introduced as liquid-crystalline bench-mark compounds. The materials chosen are affordable, stable, easy to handle and possess nematic mesophases between 30–54·9 and 24–103·4°C. All relevant macroscopic physical properties, such as refractive indices n o n e, dielectr…
Abstract not Available.
Electrical conductivity of quartz during y‐irradiation has been studied at 295 K. A significant electric current was observed in z‐cut quartz, but it could not be measured at all in x‐cut quartz, y‐cut quartz, and amorphous silica. The mobile ionic species produced during y‐irradiation migrate eflciently along the c a…
Glass in the MgO‐Li 2 O‐A1 2 O 3 ‐SiO 2 system was observed to crystallize readily at temperatures from 700° to 900°C. The primary crystalline phase evolved was Li 2 Si 2 O 5 , and the secondary phase evolved was Li 2 SiO 3 . The glass was amorphous after heating in air at 1050°C for 30 min. The addition of 0.5 wt% Si…
Luminescence excitation spectra in barium fluorohalides have been studied using synchrotron radiation of the SIBERIA-I electron storage ring in the energy range from 4 to 35 eV. The energy position of edge and core exciton formation as well as that of the electronic excitation multiplication threshold have been establ…
Abstract A cation radical salt between a π-electron donor decacyclene and hexafluorophosphate, (Dc)3(PF6)2, was prepared by electrochemical synthesis, and conductivity (90–350 K), electron paramagnetic resonance (4–400 K) and static susceptibility (2–300 K) were measured. The salt was found to be semiconductive with t…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectronic structure of one-dimensional linear halogen-bridged gold chainsChristoph Janiak and Roald HoffmannCite this: Inorg. Chem. 1989, 28, 14, 2743–2747Publication Date (Print):July 1, 1989Publication History Published online1 May 2002Published inissue 1 July 1989https:/…
Local spin-density calculations have revealed that the degree of the local distortion to the Ni-${\mathrm{O}}_{6}$ octahedra in ${\mathrm{La}}_{2}$${\mathrm{NiO}}_{4}$ has profound effects on its electronic and magnetic properties. In particular, the antiferromagnetism is strongly dependent on the ratio of the Ni-${\m…
A model of controlling the temperature in heat conduction is considered; the control mechanism is accomplished by means of a hysteresis operator that depends on some parameters. A cost functional is introduced that depends on these parameters and then properties for the optimal parameters are derived.