Materials Literature
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Confinement in nanostructures with (some of the) linear dimensions small compared to the exciton radius provides a possibility of enhancement of both the binding energy and the oscillator strength of excitons. Moreover in such structures the possibility arise of controlling the strength of Coulomb interaction, respons…
A series of dinuclear M(III) (M = Fe or Ga) catecholate complexes has been prepared using bisbidentate catecholate ligands ( L ). The products contain discrete, dinuclear M 2 ( L ) 3 6- anions featuring pseudo-octahedral coordination centers. The helical nature of the dinuclear complexes has been established by CD spe…
The use of in situ methods to study the synthesis of materials from sol−gel precursors is reviewed, with particular emphasis on the formation of crystalline phases from solid gel precursors and the crystallization of zeolitic materials from solution under hydrothermal conditions. A wide range of studies that have been…
We present a method for estimating the hopping rate for Zwanzig’s model of self-diffusion in liquids [R. Zwanzig, J. Chem. Phys. 79, 4507 (1983)]. To obtain this estimate, we introduce the cage correlation function which measures the rate of change of atomic surroundings, and associate the long-time decay of this func…
A subtilisin excreted by the Antarctic Bacillus TA39 has been purified to homogeneity and characterised. Two independent genes subt1 and subt2 are present but only subt1 is expressed significantly in the culture medium. The enzyme displays the usual characteristics of cold enzymes i.e. a high catalytic efficiency at l…
The properties of hydrogenated carbon films deposited from a highly ionized hydrocarbon plasma beam are studied as a function of deposition temperature. At low temperatures, the films have high sp3 bonding, density, and compressive stress and are very smooth. Two transition temperatures are observed, a lower transitio…
The dynamics of different molecular modes in four antiferroelectric liquid crystal substances have been studied by a combination of spectroscopic methods.The fastest motion is the reorientation around the molecular long axis, here found in the low GHz range by time domain spectroscopy. The reorientation around the sho…
A series of carbosilane dendrimer generations, G0 to G3, with 4, 12, 36, and 108 end groups, respectively, has been functionalized with perfluorohexyl (C 6 F 13 −) groups on the surface. Quantitative perfluoroalkylation of the dendrimer surface was achieved via free radical addition of 3,3,4,4,5,5,6,6,7,7,8,8,8-tridec…
We have studied the formation of platinum nanoparticles in an ethanol−water mixture with an ethanol volume fraction of 0.6 by ethanol reduction of PtCl 6 2 - in the presence of poly( N -isopropylacrylamide) (PNIPAAm−Pt) by UV−visible spectrophotometry. As predicted by calculation, a maximum at 215 nm in the absorption…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTNoncovalent Synthesis of Layered and Channel Structures involving Sulfur-Mediated Hydrogen BondsV. R. Pedireddi, Swati Chatterjee, Anupama Ranganathan, and C. N. R. RaoView Author Information Chemistry & Physics of Materials Unit Jawaharlal Nehru Centre for Advanced Sc…
Cyclodextrins (CDs) were found to form inclusion complexes with aliphatic polyesters [−O(CH 2 ) x OCO(CH 2 ) 4 CO] n (where x = 2, 3, or 4) to give crystalline compounds. α- and γ-CD formed complexes with these polyesters in high yields, although β-CD gave complexes in moderate yields. Although the yields of the compl…
Bacterial Delta5-3-ketosteroid isomerase (KSI) catalyzes a stereospecific isomerization of steroid substrates at an extremely fast rate, overcoming a large disparity of pKa values between a catalytic residue and its target. The crystal structures of KSI from Pseudomonas putida and of the enzyme in complex with equilen…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTLarge Dipole Moments of Phosphorus-Containing DendrimersMarie-Laure Lartigue, Bruno Donnadieu, Christophe Galliot, Anne-Marie Caminade, Jean-Pierre Majoral, and Jean-Pierre FayetView Author Information Laboratoire de Chimie de Coord…
The cell wall of a diatom is made up of a silica-based scaffold and organic macromolecules. Proteins located in the cell wall are believed to control morphogenesis of the species-specific silica structures of the scaffold. However, data that correlate distinct silica elements and specific proteins within the diatom ce…
An approach for the construction of diffusion-limited size-selective sensors is described based on the self-assembly of cyclic peptides into tubular channels in organosulfur self-assembled monolayers on gold films. An eight-residue cyclic peptide of alternating units of d -Leu and l -Trp amino acid residues was incorp…
Electrochemical insertion of Li into a series of “nanocomposites” comprised of alternating V 2 O 5 sheets and conductive polymer layers [polypyrrole (PPY) and polyaniline (PANI)] was examined and compared to the pristine V 2 O 5 material in terms of reversibility, Li site occupancy, and Li diffusion coefficients, and…
Genetic research programs such as the human genome project have demonstrated the need for selective detection of nucleic acids at ultralow concentrations (McKusik, V. A. FASEB J. 1991, 5, 12−20. Cui, X.; et al. Proc. Natl. Acad. Sci. U.S.A. 1989, 89, 9389−9393). Current detection techniques require amplification of th…
Using molecular-dynamics computer simulations, we investigate the dynamics of the rotational degrees of freedom in a supercooled system composed of rigid, diatomic molecules. The interaction between the molecules is given by the sum of interaction-site potentials of the Lennard-Jones type. In agreement with mode-coupl…
Packings of spheres serve as useful models of the geometry of many physical systems; in particular, the description of the void region in such packings (the region not occupied by the spheres) is crucial in many studies. The void region is, in general, composed of disconnected cavities. We present an algorithm for dec…
The crystal structures of three porphyrin diacid species, [H 4 OEP](ClO 4 ) 2, [H 4 TPP](ClO 4 ) 2, and [H 4 TMP](ClO 4 ) 2, have been determined from low-temperature X-ray diffraction data to delineate how the peripheral substituents of the porphyrin affect the overall molecular flexibility . [H 4 OEP](ClO 4 ) 2 (|C…