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。
Strong metal-based emission with [TbL1] in aqueous media occurs in the absence of protons and oxygen; dissolved molecular oxygen quenches the phenanthridyl triplet (1/KSV = 58 Torr O2) but back-energy transfer to the organic triplet occurs efficiently only with the excited protonated complex (pKa″ = 5.7).
The absolute configuration of the four stereoisomeric α-substituted derivatives of dota has been defined; in their Eu complexes, 2D-NMR methods have revealed that in solution ring inversion is independent of pendant arm rotation and the (RRRR)-[EuL1a] complex which in the solid state crystallises as a square antiprism…
The ferroelectric critical point has been found in a ferroelectric polymer by exploring the influence of the electric field on the paraelectric-ferroelectric phase transition. Dielectric and pyroelectric measurements on 30-monolayer-thick films of the crystalline copolymer poly(vinylidene fluoride-trifluoroethylene) g…
Part 1 The Surface Energy of Solids: The Phenomenon of Rupture and Flow in Solids, A.A. Griffith Analysis of Stresses and Strains Near the End of a Crack Traversing a Plate, G.R. Irwin Crack Propagation in Continuous Media, G.P. Cherepanov The Next 50 Years of Jet Propulsion, B.L. Koff. Part 2 The Mathematical Theory…
A finite element model of polarization switching in polycrystalline ferroelectric ceramics is developed. A polarization switch in a ferroelectric is the reorientation of the unit cell dipole to a new crystallographic direction. It is assumed that a crystallite switches if the reduction in potential energy of the polyc…
A Finnis/Sinclair-type interatomic potential for copper is used to examine the properties of dissociated screw dislocations in the face-centred cubic lattice.The critical stress for dislocation motion is found to be a sensitive function of the partial dislocation separation, with a lower limit at least 85% smaller tha…
A study by Raman spectroscopy of the oxomolybdate surface phase present on an Mo/Al2O3 oxidic precursor reveals the presence of well dispersed 6-molybdoaluminate entities (AlMo6O24H63-) on a 15 wt.% MoO3 oxidic precursor. It is also shown that precipitation of an ammonium 6-molybdoaluminate salt occurs at higher Mo lo…
Reversible displacement of up to two metal bound water molecules at a coordinately unsaturated, cationic lanthanide centre is signalled by increases in the luminescence intensity or lifetime of the emissive lanthanide: selective chelation of hydrogencarbonate is consistent with emission spectroscopic, ESMS and CPL mea…
The meso-octaethylporphyrinogen–sodium–lanthanide complexes, [{(η5 : η1 : η5 : η1-Et8N4)M}Na(thf)2], in the presence of Na metal and under a nitrogen atmosphere, fix and reduce dinitrogen to the [N2]2– anion, as shown by the isolation of the dinuclear complexes containing the [M(µ-η2 : η2-N2)M] moiety [M = Pr, Nd].
Recently, several diagnostic methods for measurement of permittivity and dielectric loss have been developed for non-destructive testing of water-tree degraded XLPE cables. Critical degradation is found to be associated with a more than proportional increase of the dielectric properties when increasing the applied tes…
Tubulin liganded with GTP at the N-site in the alpha-subunit and with GDP at the E-site in the beta-subunit (GDP-tubulin) reversibly binds one high affinity Mg2+ cation (Kb = 1.1 x 10(7) M-1), whereas tubulin liganded with GTP at both subunits (GTP-tubulin) binds one more high affinity Mg2+. The two cation binding loc…
Adaptation of the polymer matrix has allowed high enantioselectivity to be achieved for the first time with a polymer-supported chiral MnIII(salen) alkene epoxidation catalyst.
An intramolecular Zn–O2H3–Zn bridge as a complexed form of metal-bound hydroxide exhibits enhanced reactivity compared to the related Zn–OH–Zn unit, illustrated by the reaction with CO2.
Aluminosilicate MCM-41 materials prepared by post-synthesis alumination using aqueous aluminium chlorohydrate exhibit remarkably high mechanical and hydrothermal stability and in addition the materials, after steaming at high temperatures, possess stronger Brønsted acid sites compared to the parent material.
A synthetic route was developed for the preparation of trans-[Ru(NH3)4(NO)X]n+, where X = isonicotinamide (isn), pyrazine (pyz) or sulfite, and cis-[Ru(NH3)4(NO)(NO2)]2+. The complexes have been characterized by elemental analysis, UV/VIS, infrared, 1H NMR and ESR spectroscopies, molar conductance measurements and cyc…
We have begun studies of a novel type of biomaterial derived from a recently-discovered class of ionic self-complementary oligopeptides. These short peptides (typically 8, 16, 24, or 32 amino acid residues with internally-repeating sequences) self-assemble in aqueous salt solution into three-dimensional matrices capab…
We have found that liquid crystals can be aligned on a polyimide surface exposed to a low energy and neutral argon ion beam. The energy of the incident ions was varied between 75 eV and 500 eV, the integrated current density from 20 µA/cm 2 to 500 µA/cm 2 , and the angle of incidence over which alignment was measured…
The size and excitation dependence of resonant low-frequency Raman scattering in CdS nanocrystals (radii less than 10 nm) embedded in a glassy matrix have been investigated. We report a size-selective excitation for excitations inside the absorption features. The Raman spectra exhibit a different behavior when the exc…
Carbon nanotubes were produced in large amounts by catalytic decomposition of acetylene over a Co incorporated zeolite NaY support. Purification of multi-wall nanotubes was required in order to eliminate catalyst and amorphous carbon produced by thermal decomposition of hydrocarbon. First, separation of nanotubes and…
Ti-MCM-41 materials with methylated silicons have been prepared in one step synthesis; the resultant organic–inorganic composites are highly stable and present the highest activity and selectivity ever reported on Ti containing mesoporous catalysts for the epoxidation of olefins using organic peroxides.