Materials Literature
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We studied the glass transition dynamics of polystyrene micronetwork colloids with an average cross-link density of 1:50 (inverse number of monomer units between cross-links) and a hydrodynamic radius of about 100 nm by dynamic light scattering. Special emphasis was put on extracting correct intermediate scattering fu…
The flow properties of aqueous suspensions of silica particles with diameters ranging from 117 to 780 nm were measured as a function of volume fraction, ionic strength, and continuous phase composition. Dense, aqueous suspensions of all sizes displayed similar behavior with a yield stress in the limit of low shear rat…
We have calculated the electronic structures of five different manganese-oxo dimer complexes using density functional methods combined with the broken symmetry and spin projection concepts. The number of carboxylate, oxo, and peroxo bridging ligands was varied, and the terminal ligands were triazacyclononane (TACN). T…
Globular proteins can be crystallized by the addition of electrolyte or nonadsorbing polymer. Too much additive, however, gives rise to amorphous precipitates. By comparing existing data on various proteins with previous work on a model colloid-polymer mixture, we suggest an explanation for noncrystallization in terms…
Weblike aggregates of coalesced Si nanocrystals are produced by a laser vaporization−controlled condensation technique. SEM micrographs show particles with ∼10 nm diameter but the Raman shift suggests the presence of particles as small as ∼4 nm. FTIR of the freshly prepared particles shows weak peaks due to the stretc…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTThermal Derivatization of Porous Silicon with AlcoholsNamyong Y. Kim and Paul E. LaibinisView Author Information Departments of Chemistry and Chemical Engineering Massachusetts Institute of Technology Cambridge, Massachusetts 02139 Cite this: J. Am. Chem. Soc. 1997, 11…
The crystallization of oxyethylene/oxybutylene (E/B) diblock copolymers has been studied by simultaneous SAXS and WAXS. The copolymers crystallized from their melts (disordered, lamellar, or hexagonal) with folded E blocks. Rapid crystallization (quench) of lamellar melts was accompanied by a change in length scale an…
The protonated form of the ligand 2,6-bis(1'-methylbenzimidazol-2'-yl)pyridine crystallizes as its perchlorate salt (HL(1))ClO(4) (1) in the orthorhombic system Pbca, with a = 13.976(3) Å, b = 14.423(3) Å, c = 19.529(4) Å, Z = 8. The proton is located on one benzimidazole N-atom, and the two N-methyl substituents lie…
The X-ray structure of the &mgr;-carboxylate-&mgr;(1,1)-azido-bridged compound {[Cu(Hpht)(N(3))].H(2)O}(n)() has been determined (Hpht = hydrogen phthalate). Crystal data: formula C(8)H(7)CuN(3)O(5), monoclinic, P2(1)/m (No. 11), a = 7.383(3) Å, b = 6.568(4) Å, c = 10.659(4) Å, beta = 93.38(3) degrees, Z = 2. The comp…
We have measured the dc magnetization at low temperatures of tetragonal crystals of ${\mathrm{Mn}}_{12}$ acetate complex [${\mathrm{Mn}}_{12}$ ${\mathrm{O}}_{12}$ (${\mathrm{CH}}_{3}$ COO${)}_{16}$ (${\mathrm{H}}_{2}$ O${)}_{4}$ ], a material composed of a large (Avogadro's) number of identical magnetic molecules, eac…
A purification procedure for single-walled nanotubes is presented in this report. A novel purification method that incorporates the hydrothermal treatment along with other treatments such as extraction of fullerenes and oxidation and dissolution of metal particles is used in this study. The effects of each treatment i…
Molecular-dynamics and total-energy calculations using a realistic three-body potential for carbon reveal the basic atomic processes by which single-shelled nanotubes can grow out of metal-carbide particles by the root growth mechanism. We find that nanometer-sized protrusions on the metal-particle surface lead to the…
Theoretical and experimental advances in determination of three-phase invariants by multiple-beam X-ray diffraction are reviewed. The fundamental physics and mathematical analyses are explained. Plane-wave dynamical theory for the interpretation of multiple-beam interference is summarized. New results of its applicati…
Experiments were performed to examine differences in bubble cavitation inception, form, and acoustic emission in fresh and salt water. The tests were conducted on an axisymmetric headform known as the ITTC body, and acoustic emission, cavitation bubble size, and cavitation event rates were measured for a variety of ca…
Abstract This investigation was performed to resolve long‐term contradicting theories regarding the mechanisms which govern the species diffusion across the liquid B 2 O 3 layer covering a single boron particle during the combustion of boron. An environmental scanning electron microscope (ElectroScan E‐3) was used to…
Abstract The characterization, pillaring ability and some catalytic properties of a saponite from the Vicálvaro deposit of Tolsa, located in Madrid have been studied. This mineral is associated with sepiolite in the same lacustrine environment. The raw saponite presents, as special characteristics, high specific surfa…
Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn Email Tools Icon Tools Get Permissions Cite Icon Cite Search Site Citation Russel Barsh; The Epistemology of Traditional Healing Systems. Human Organization 1 March 1997; 56 (1): 28–…
This Innovations Deserving Exploratory Analysis (IDEA) project focused on an evaluation of the feasibility of using composite rebar in concrete reinforcement based on studies of the properties of basalt fiber and reinforced composite. The progress report focuses on the technical characteristics of basalt-fiber composi…
Abstract Injection molded β‐crystalline phase polypropylene (PP) composites containing 5, 10, 20, 30 and 40% (by weight) of talc filler were studied by X‐ray diffraction, scanning electron microscopy, static tensile and falling drop weight impact tests. The X‐ray diffraction analysis showed that the talc filler suppre…
Suitable parameter sets for the CHARMm force field were derived using the Dinur−Hagler energy second-derivative procedure, on the basis of SCF calculations at the 6-31G* level, for the uncommon structural units in poly(phenoxyphosphazenes) [P N, P N, P X (X = aryloxy)]. It is shown that application of molecular dynami…