Materials Literature
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A systematic classification of the tourmaline-group minerals, general formula X Y3Z6 (T6O18) (BO3)3 V3W, is proposed, based on chemical composition and ordering at the different crystallographic sites of the tourmaline structure. There are currently thirteen accepted tourmaline species. However, based on the actual ch…
Hydrogen adsorption on crystalline ropes of carbon single-walled nanotubes (SWNT) was found to exceed 8 wt. %, which is the highest capacity of any carbon material. Hydrogen is first adsorbed on the outer surfaces of the crystalline ropes. At pressures higher than about 40 bar at 80 K, however, a phase transition occu…
Poly(ethylene glycol)-poly(L-lactide) diblock and triblock copolymers were prepared by ring-opening polymerization of L-lactide with poly(ethylene glycol) methyl ether or with poly(ethylene glycol) in the presence of stannous octoate. Molecular weight, thermal properties, and crystalline structure of block copolymers…
The syntheses and characterizations of the novel platinum(II) mono-1,2-dithiolenes (COD)Pt(dddt) ( 1 ), (Ph 3 P) 2 Pt(dddt) ( 2 ), (COD)Pt(edt) ( 3 ), (Ph 3 P) 2 Pt(edt) ( 4 ), (bipy)Pt(edt) ( 5 ), and (Ph 3 P)(CO)Pt(dddt) ( 6 ) (COD = 1,5-cyclooctadiene; dddt = 5,6-dihydro-1,4-dithiin-2,3-dithiolate; edt = ethylene-1…
Whereas diphenylacetylene (DPA) exhibits no photoisomerization because of the involvement of a triple bond in the chromophore, prolonged irradiation of the films with 313-nm light resulted in the reduction of absorption, leading to insolubilization as a result of photo-cross-linking. When the actinic light is linearly…
The geometry, conformational behavior, and magnetic properties of 2-(2-imidazolyl-)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, an important spin carrier in molecular magnetic materials, have been studied by a combined experimental and theoretical approach. From the experimental point of view, the avaliable structu…
Molecular mechanics have been used to rationalize the structures of the layered double hydroxide intercalates [LiAl 2 (OH) 6 ]Cl, [LiAl 2 (OH) 6 ]Br, and [LiAl 2 (OH) 6 ]NO 3 . The simulations showed that calculated lowest energy structures were in good agreement with the experimentally determined structures and were…
The enzymatic degradation of intramolecularly polymerized methacrylated dextran [dex-poly(MA)] and hydrogels based on methacrylated dextran was studied. Dex-poly(MA) was synthesized as a soluble model compound to investigate the enzymatic degradation of dextran hydrogels. After degradation of hydrogels and dex-poly(MA…
A new precursor for the sonochemical preparation of amorphous nickel, Ni(cyclooctadiene) 2, yielded relatively large (200 nm) amorphous nanoparticles composed of nickel and carbon atoms. Small nickel particles were dispersed all over the particle. When these particles were heated slightly above their crystallization t…
Polymeric microtubules and nanofibrils have been prepared by depositing a solution of the desired polymer within the pores of microporous template membranes. Both microporous alumina and track-etched polyester membranes were used as the templates. Tubules and fibrils composed of polystyrene, poly(2,6-dimethyl-1,4-phen…
A method for solving structures from powder diffraction data was developed, and its validity was demonstrated on three complex structures. The method uses a textured sample and exploits the high intensity and parallel nature of synchrotron radiation. In principle, crystal structures as complex as those routinely solve…
Titanium-containing porous silica with a mesostructured unit as secondary pore walls has been synthesized at room temperature by a modified sol−gel method using a structure-directing agent. The transparent gel formed as a precursor resulted in high titanium incorporation in the silicate framework of up to 15 mol % Ti.…
A series of mesoporous vanadosilicate V-MCM-41 molecular sieves with variable Si/V ratios have been hydrothermally synthesized at pH = 10. These materials were investigated by powder X-ray diffraction (XRD), framework FTIR, diffuse reflectance UV−visible spectroscopy, nitrogen sorption measurement, scanning electron m…
In Escherichia coli the coenzyme pyridoxal 5'-phosphate (PLP) is synthesised de novo by a pathway that is thought to involve the condensation of 4-(phosphohydroxy)-L-threonine and 1-deoxy-D-xylulose, catalysed by the enzymes PdxA and PdxJ, to form either pyridoxine (vitamin B6) or pyridoxine 5'-phosphate (PNP). Here w…
The bis-hydroxamate ligand isophthal-di- N -(4-methylphenyl)hydroxamate ( E ) forms tetrahedral clusters of the type M 4 E 6 (M = Ga(III), Fe(III)). The syntheses of these and several other tetrahedral metal clusters have illustrated a general approach to the design of supramolecular metal clusters based on incommensu…
Pd/alumina composite membranes were fabricated using the generally practiced electroless plating process involving two-step activation of a symmetric 0.2 μm α-alumina microfilter with tin (Sn) chloride sensitizer (containing SnCl 2 and SnCl 4 ) and palladium(II) chloride (PdCl 2 ). Pd films were deposited on these act…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTExploiting Differences in Sialoside Expression for Selective Targeting of MRI Contrast ReagentsGeorge A. Lemieux, Kevin J. Yarema, Christina L. Jacobs, and Carolyn R. BertozziView Author Information Department of Chemistry, University of California Berkeley, California…
We study ground-state orderings of particles in classical lattice-gas models of adsorption on crystal surfaces. In the considered models, the energy of adsorbed particles is a sum of two components, each one representing the energy of a one-dimensional lattice gas with two-body interactions in one of the two orthogona…
Thin films of diblock copolymer subject to gravitational field are simulated by means of a cell dynamical system model. The difference in density of the two sides of the molecule and the presence of the field causes the formation of lamellar patterns with orientation parallel to the confining walls even when they are…
Gold−silver alloy nanoparticles with varying mole fractions are prepared in aqueous solution by the co-reduction of chlorauric acid HAuCl 4 and silver nitrate AgNO 3 with sodium citrate. As the optical absorption spectra of their solutions show only one plasmon absorption it is concluded that mixing of gold and silver…