Materials Literature
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The properties of dendrimers (“starburst” molecules) under varying solvent conditions are studied using molecular dynamics simulations. The dendrimers are found to have a compact (space filling) structure under all solvent conditions, with a radius of gyration which scales with the number of monomers as R G ∝ N 1/3 .…
Many processes have been considered over the years to explain the origin of breakdown in cable insulation. Such effects as space charge build-up, tree growth, charge injection, etc. have all been discussed. Various techniques are now available to measure, in a nondestructive way, space charge distributions in insulato…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTEvidence of a Novel Side Chain Structure in Regioregular Poly(3-alkylthiophenes)T. J. Prosa, M. J. Winokur, and R. D. McCulloughView Author Information Department of Physics, University of Wisconsin, Madison, Wisconsin 53706 Departm…
High chromium white irons are ferrous based alloys containing 11–30 wt-% chromium and 1.8–3.6 wt-% carbon, with molybdenum, manganese, copper, and nickel sometimes added as additional alloying elements. The microstructure of these alloys typically consists of hard primary and/or eutectic carbides in a matrix of austen…
Abstract This paper presents a critical review of the basic data concerning the physics and chemistry of low pressure SiH 4 glow discharges used to deposit hydrogenated amorphous silicon films (a‐Si:H). Starting with an updated table of thermochemical data, we analyze the gas‐phase elementary processes consisting of i…
Differences between the surface chemical properties of hydrogen- and nitrogen-treated samples of an activated carbon were quantified using several complementary techniques. Calorimetric studies conducted at 303 K revealed that the sample treated in N 2 at 1223 K adsorbs a great deal of oxygen with unusually high diffe…
To study the role of oligosaccharides on the properties of glycoproteins, five glycoproteins (yeast external invertase, bovine serum fetuin, glucoamylase from Aspergillus niger, and chicken egg white ovotransferrin and avidin) of previously established glycan patterns were purified to homogeneity and deglycosylated wi…
Modification of the polyol process has enabled the synthesis of nanometre-sized silver particles with a narrow size distribution. Dispersions of colloidal silver have been prepared by the reduction of silver nitrate in ethylene glycol in the presence of a polymeric protective agent, namely polyvinylpyrrolidone (PVP).…
A new class of chromophores has been fabricated that features both electron-releasing and electron-withdrawing groups fused via an intervening ethynyl moiety to the carbon framework of a (porphinato)metal complex. These species possess large molecular first-order hyperpolarizabilities (β). We report herein the synthes…
Colloidal copper particles were prepared in aqueous solution via the reduction of copper dodecyl sulfate, Cu(DS) 2, by sodium borohydrate. Below the critical micellar concentration (cmc), it has been obtained isolated particles forming an interconnected network of either oxide or pure metallic copper aggregates. Synth…
Analogue calorimetry for blends of poly(vinyl ester)s and polyacrylates has been studied. Hydrogenated monomers were used as analogues of the corresponding polymers. It is found that isomeric esters differing only in the orientation of the COO group mix with only small heat change, which can be positive or negative. T…
PLA/PEO/PLA triblock copolymers bearing short poly( l -lactic acid) blocks, with the number average degree of polymerization of each PLA block PLA = 2, 4, 8, and 12, were synthesized by ring opening polymerization of l -lactide initiated by poly(ethylene glycol) in the presence of CaH 2 . The length of PEO blocks was…
Colloidal gold nanoparticles with an average radius of 15 nm have a surface plasmon absorption band at 530 nm. Excitation by laser pulses of 450 fs duration, and wavelength of 600 or 380 nm “bleached” the plasmon band and produced a transient absorption at the wings of the “bleach” spectrum. The transient absorption w…
Macrocyclic dicopper(II) complexes derived from 2,6-di(R)formylphenols and various linking diamines are surveyed and their magnetic and structural properties assessed. For those systems with "flat" dinuclear centers and no electronic perturbations associated with electron-withdrawing ligands or ligand groups, the comp…
The preparation, crystal structures, and electric and magnetic properties of (BETS) 2 MX 4 molecular conductors (BETS = bis(ethylenedithio)tetraselenafulvalene; M = Mn 2+, Fe 3+, Co 2+, Ni 2+, Cu 2+; X = Cl, Br, CN) are reported. Resistivity measurements down to 2 K reveal the coexistence of the BETS π conduction elec…
The crystallization boundaries of small, attractive particles are found to be identical when interactions are modeled as adhesive hard spheres. Based on experimental results and the attraction range, we conclude that solubility is insensitive to interaction details and various colloidal particles will only display equ…
Orientational ordering of faceted nanocrystals in nanocrystal arrays has been directly observed for the first time, by use of transmission electron microscopy imaging and diffraction to resolve the structure of thin molecular-crystalline films of silver nanocrystals passivated by alkylthiolate self-assembled monolayer…
The oxidation of formic acid on thin, epitaxially-grown Pd overlayers on Au and Pt single crystal electrodes was studied as a function of overlayer thickness ranging from submonolayer coverages up to the equivalent of 10 monolayers. The results were compared with those for massive Pd single crystal surfaces. The elect…
Four different kinds of C 60 -linked zincporphyrins have been prepared by changing systematically the linking position at meso -phenyl ring from ortho to para and their photophysical properties have been investigated. Regardless of the linkage between the two chromophores, photoinduced charge separation (CS) and subse…
Temperature-programmed isotopic exchange of 18 O 2 with 16 O of several oxides was carried out in the 200−900 °C temperature range. The oxides can be ranked according to their maximal rates of exchange obtained at the following temperatures: CeO 2, 410 °C ≫ CeO 2 -Al 2 O 3, 480 °C ≈ MgO, 490 °C > ZrO 2, 530 °C ≫ γ-Al…