Materials Literature
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Ultrathin films of two perylene dyes, 3,4,9,10-perylenetetracarboxylicdianhydride (PTCDA) and N, N ‘-di- n -butylperylene-3,4,9,10-bis(dicarboximide) (C4−PTCDI), have been grown on the (001) faces of freshly cleaved single crystal, NaCl, KCl, and KBr. Tapping mode AFM studies of these materials show that their crystal…
The twelve phosphide oxides RZnPO (R = Y, La-Nd, Sm, Gd-Tm) and the nine arsenide oxides (R = Y, La-Nd, Sm, Gd-Dy) have been prepared by reaction of the rare earth elements, ZnO, and phosphorus or arsenic, respectively, in a NaCl/KCl flux. The compounds RZnPO (R = Y, Pr, Nd, Sm, Gd-Tm) crystallize with a new trigonal…
Catalytic activities and deactivation characteristics of oxides-supported nickel catalysts for the reaction of methane reforming with carbon dioxide were investigated. The dynamic carbon deposition on various nickel catalysts was also studied by a thermogravimetric method. Among the catalysts prepared, Ni/La 2 O 3, Ni…
Clavaminate synthase (CS) is one member of a large class of non-heme iron enzymes that require α-ketoglutarate (α-KG) as a cosubstrate. While the majority of this class catalyzes the hydroxylation of unactivated C−H bonds, CS is unusual in that in addition to performing hydroxylation chemistry, it also catalyzes the k…
The distance dependent interaction between polyelectrolyte-covered mica surfaces in aqueous solution was investigated with the surface forces apparatus. We find the following: (i) The surface charge changes sign, when an oppositely charged polyelectrolyte from a concentrated polyelectrolyte solution is adsorbed. (ii)…
Chemical vapor deposition of germanium onto the silicon (001) surface at atmospheric pressure and 600 degrees Celsius has previously been shown to produce distinct families of smaller (up to 6 nanometers high) and larger (all approximately 15 nanometers high) nanocrystals. Under ultrahigh-vacuum conditions, physical v…
Void shape changes induced by electromigration pose reliability problems in Al-based interconnects. Recent observations have shown that a rounded void sometimes collapses to a transverse slit in an interconnect with bamboo-like grain structure. This article provides a linear stability analysis for a circular void that…
Tetrasodium heptacobalt hexaphosphate, a new monophosphate prepared by hydrothermal methods, comprises CoO6 and CoO4 coordination polyhedra connected to each other by corner and edge sharing to form zigzag layers parallel to the ab plane. These layers are interconnected by Co – O polyhedra and P – O tetrahedra via cor…
A phenomenological model for quantum phase slips of charge-density waves that takes into account the system-size effect is presented. The process of quantum nucleation leading to the phase slip changes from vortex-pair to vortex-ring creations as the external electric field increases, which is analogous to the evoluti…
Aliphatic polyimides (P-XBTA) having inherent viscosities of 0.4–1.4 dL/g were readily synthesized by the high-pressure polycondensation of the salt monomers, composed of aliphatic diamines having various methylene chain lengths (X = 4–12) and 3,3′,4,4′-benzophenonetetracarboxylic acid (BTA), under 200–250 MPa at 200–…
Transverse magnetic relaxation properties of protons attached to PEO chains were investigated in compatible blends of hydrogenated PEO and deuterated PMMA by varying the PEO concentration and the temperature. The onset of segmental fluctuations is observed for samples that do not crystallize (φ ≤ 0.31); it occurs abov…
HREM and FEG TEM were emphasized and extensively used to follow the most subtle changes in the structure and composition of ball-milled Cu, Fe-Cu, and thermally decomposed Fe60Cu40. Some significant results are obtained and summarized as follows: HREM shows that the deformation of ball-milled copper proceeds mainly by…
Gas barrier properties of alkylsulfonylmethyl-substituted poly(oxyalkylene)s are discussed. Oxygen permeability coefficients of three methylsulfonylmethyl-substituted poly(oxyalkylene)s, poly[oxy(methylsulfonylmethyl)ethylene] (MSE), poly[oxy(methylsulfonylmethyl)ethylene-co-oxyethylene] (MSEE), and poly[oxy-2,2-bis (…
The phase and orientational behaviors of a series of liquid crystalline (LC) AB-type diblock copolymers comprising thermotropic main-chain (MC) polyester and side-group (SG) polymethacrylate blocks were investigated by X-ray diffraction. The MC and SG blocks were phase separated and gave rise to their individual mesop…
Synthesis of nanocomposite two-phase permanent magnet materials by mechanical milling requires optimization of the volume fractions of the two phases, milling time, heat treatment temperature, and time. In the present study, optimization of milling time, heat treatment temperature, and time have been carried out by fi…
Ultraviolet-photoemission spectroscopy has been employed to investigate the valence-band electronic structures of the magnetic alloys ${\mathrm{Co}}_{2}\mathrm{MnSn},$ ${\mathrm{Cu}}_{2}\mathrm{MnAl},$ and ${\mathrm{Pd}}_{2}\mathrm{MnSn}.$The valence band of ${\mathrm{Co}}_{2}\mathrm{MnSn}$ extends to approximately 5…
The recent results for the contact value of the radial distribution function obtained from large-scale molecular dynamics and Monte Carlo simulations of systems of dense hard spheres [M. D. Rintoul and S. Torquato, J. Chem. Phys. 105, 9258 (1996)] are compared to those of the Padé equation of state for a hard-sphere f…
The enthalpy relaxation of a series of linear amorphous polyesters (poly(propylene isophthalate) (PPIP), poly(propylene terephthalate) (PPTP), poly(ethylene terephthalate) (PETP), and poly(dipropylene terephthalate) (PDPT)) has been investigated by differential scanning calorimetry (DSC). These polyesters have been an…
A series of viologen polymers based on 4,4‘-bipyridyl and the ditosylates of trans- 1,4-cyclohexanedimethanol and 1,8-octanediol was prepared by the quaternization reaction in acetonitrile. Their polyelectrolyte behavior in a common organic solvent was studied by viscosity measurements, and their chemical structures w…
We have calculated a set of crystal-field parameters, Bnm, for Dy3+ through Yb3+ ions in M (II) sites in the crystal Sr5(PO4)3F (SFAP). The Bnm parameters were derived from lattice-sum calculations and from analyses of the optical spectra reported for Ho3+, Er3+, and Tm3+ individually doped into SFAP. These parameters…