Materials Literature
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We report on the first Raman data of Cu substituted La(1-y)Sr(y)Mn(1-x)Cu(x)O3 (0 < x < 0.10 and 0.17 < y < 0.3, accordingly in order to have the same Mn(4+)/[Mn(4+)+Mn(3+)] ratio), collected in the frequency range 100-900 cm-1 and at room temperature, with parallel and crossed polarizations of the incident and scatte…
The T-dependence of magnetic moments in SrB_6 is studied through spin-polarized band calculations for a supercell of Sr_{27}B_{156} containing a B_6 vacancy. The magnetic moment decays rather quickly with T despite the fact that only electronic Fermi-Dirac effects are included. This result and the T-dependence of mome…
No metal jacket required: The surface structures of mesoporous materials were accurately determined by using electron-microscopy techniques—without the need for metal plating. The effectiveness of these techniques was demonstrated with SBA-15 mesoporous silica (see image) and its CMK-5 carbon replica, for which high-r…
Very different electronic properties are found in the hexagonal and lamellar nanocomposite films (see schematic representations) prepared by dilution of a pyrrole-containing surfactant with nonpolymerizable surfactants in a sol–gel-based template polymerization. The hexagonal composite film comprises a thin polypyrrol…
In an effort to make semiconductor nanomaterials with tunable properties, we have deliberately designed and synthesized a family of novel organic-inorganic hybrid nanocomposites based on II-VI semiconductors with structures ranging from one-dimensional (1-D) chain to two-dimensional layer (2-D) to three-dimensional (3…
A recent paper [J. B. Pendry, Phys. Rev. Lett. 85, 3966 (2000)] showed how to construct a superlens that focuses the near-field radiation and, hence, produce an image resolution unlimited by wavelength. The prescription requires lossless materials with a negative refractive index: finite loss cuts off the finer detail…
By means of ab initio supercell calculations based on the density-functional theory, we have investigated stability of hydrogen-monovacancy complexes $({\mathrm{VH}}_{n})$ and their binding preferences in $\ensuremath{\alpha}\ensuremath{-}\mathrm{Fe}.$ We have found that ${\mathrm{VH}}_{2}$ is the major complex at amb…
We present the results of a comprehensive investigation of the dc magnetization, ac susceptibility, and magnetotransport properties of the glassy ferromagnet ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CoO}}_{3}.$ The compositions studied span the range from the end-member ${\mathrm{LaCoO}}_{3}$ $(x=0.0…
The apparent contact angle on a rough surface is usually modeled by either Cassie's or Wenzel's theory. We show, on the basis of experimental evidence, that there can be two contact angles on the same rough surface, depending on how a drop is formed. A transition can occur between the different states by an external d…
OBJECTIVES: To develop and test a new concept of the degradation kinetics of newly developed coronary stents consisting of magnesium alloys. METHODS: Design of a coronary stent prototype consisting of the non-commercial magnesium based alloy AE21 (containing 2% aluminium and 1% rare earths) with an expected 50% loss o…
Insertion of spherical particles into a uniform nematic liquid crystal gives rise to the formation of topological defects. In the present work, we investigate how a spherical particle accompanied by its topological defects interacts with neighboring disclination lines. We perform two- and three-dimensional dynamic sim…
The structure of Ge nanocrystals embedded into a ${\mathrm{SiO}}_{2}$ matrix on either Si(100) or quartz-glass substrates has been studied by transmission electron microscopy, x-ray absorption fine structure, and Raman scattering. The size of the nanocrystals (5--20 nm) is found to strongly depend on the substrate mat…
Abstract A novel triblock polyisocyanide having free-base- and zinc-porphyrins as pendants was prepared by living polymerization with a Pt-Pd μ-ethynediyl complex as an initiator, and irradiated at 420 or 556 nm in a THF solution to cause intramolecular energy transfer from the zinc-porphyrin to the free-base-porphyri…
A tri-block coupling-polymer composed of 4,4'-methylenediphenyl diisocyanate and poly (ethylene oxide) (PEO), abbreviated MPEO, was used as the template surface-modifying additive (SMA), based on which selected amino acids (lysine, arginine, glycin, and aspartic acid) and RGD peptide were respectively conjugated as fu…
The energy output (work) generated by polypyrrole actuators has been determined from the actuator strain operating against a constant force. The strain decreases as the force increases leading to a maximum in the amounts per cycle at an intermediate force. The behaviour agrees well with previous analyses (Baughman 199…
The colossal magnetoresistance in manganites AMnO3 is studied from the viewpoint of multicritical phenomena. To understand the complicated interplay of various phases, we study the Ginzburg-Landau theory in terms of both the mean-field approximation and the renormalization-group analysis for comparison with the observ…
Bonding interactions between the iron and the porphyrin macrocycle of five- and six-coordinate high-spin iron(III)-porphyrin complexes are analyzed within the framework of approximate density functional theory with the use of the quantitative energy decomposition scheme in combination with removal of the vacant pi orb…
According to mode coupling theory, liquidlike motion becomes frozen at a critical temperature T(c) well above the caloric glass transition temperature T(g). Here, for the first time, we report on radiotracer diffusion in a supercooled Pd43Cu27Ni10P20 alloy from T(g) to the equilibrium melt. Liquidlike motion is seen t…
Synthesis of aromatic polyesters by chain-growth polycondensation of activated 4-hydroxybenzoic acid derivatives ( 1 ) was investigated. Model reactions of ester formation between active compounds ( 6 and 7 ) and phenolic nucleophile ( 8 ) gave the best result when 3-arylcarbonyl-2-benzothiazolone derivatives were use…
Abstract In the oilfield, due to the extensive use of water injection for oil displacement and pressure maintenance, many reservoirs experience the problem of scale deposition when injection water starts to breakthrough. In most cases the scaled-up wells are caused by the formation of sulphate and carbonate scales of…