Materials Literature
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We propose a class of networks which can be regarded as an extension of the graphitic network. These networks are constructed so that surface states with non-bonding character (edge states) are formed in a tight-binding model with one orbital for each atomic site. Besides, for several networks, the tight-binding elect…
The compounds studied in this work are sol−gel-derived organic−inorganic hybrid materials in which the two components are covalently linked via Si−C bonds. The organic part is a chromophore group derived from dipicolinic acid that is functionalized with trialkoxysilyl groups; the as-obtained silylated monomers are aft…
Mesoscopic organization in soft, hard, and biological matter is examined in the context of our present understanding of the principles responsible for emergent organized behavior (crystallinity, ferromagnetism, superconductivity, etc.) at long wavelengths in very large aggregations of particles. Particular attention i…
Supermolecular structure of drug delivery system on the basis of segmented polyurethane (SPU) has been determined to control the release of anticancer drug, cyclophosphamide (CPh). It has been established that the phase separation in SPU is essentially intensified by means of both the increase of molecular weight for…
Alternating layers of Ge quantum dots embedded in either Al2O3 or AlN matrices were deposited on sapphire substrates by pulsed-laser deposition. The characteristics of the dots are shown to be independent of the surrounding matrix. The dots size (73, 130, 160, and 260 ű5%) was controlled by the laser energy density a…
The high-field behavior of perovskite ferroelectrics close to a morphotropic phase boundary is investigated using the thermodynamic theory of ferroelectrics. For Pb(Zr0.55Ti0.45)O3, a phase transition from the rhombohedral to the tetragonal state is predicted for a critical field of approximately 4 MV m−1 parallel to…
Using a low-temperature x-ray diffraction apparatus in a high field, a systematic study was performed of the stoichiometric Ni2MnGa alloys in a wide temperature range from 10 K to room temperature and in fields up to 5 T. X-ray diffraction data at different fields clearly show the martensitic-phase transition is a two…
Isothermal crystallization and subsequent melting behavior of five samples of syndiotactic polypropylene are presented. Crystallization studies were carried out in the temperature range of 60°C to 97.5°C using a differential scanning calorimeter (DSC). Subsequent DSC scans of isothermally crystallized samples exhibite…
De novo proteins were assembled from two sets of helical peptides on cyclic peptide templates bound to cellulose membranes (see picture). The variation of the amino acids of the hydrophobic binding pocket in the antiparallel four-helix bundle tuned the redox potential of the reversibly bound FeIII – protoporphyrin IX…
The versatile TADDOL moiety has been immobilized for the first time on an inorganic support (highly porous silica gel). This gives access to Ti - Lewis acids (see picture), which turn out to be very efficient in two standard enantioselective reactions. X=OiPr, OTos.
Covalent anchoring of functional dyes in the pores of a mesoporous silicate host Si-MCM-41 (shown in the picture) is achieved with the microwave-assisted cocondensation presented here. The short reaction time (20 min) ensures that no dye degrades during the hydrothermal synthesis.
The ultrafast release of O(2) from the O(2) adduct of picket-fence cobalt porphyrin (see picture) has been probed in real time, and has a total reaction time of 2 ps, without subsequent recombination over several nanoseconds. The dynamics of this ultrafast release of O(2) shows that relaxation within the porphyrin sys…
The main variables involved in solid-state polymerization of PET homopolymers, originally with molecular weight within the commercial range, were sequentially studied to determine their influence in polymerized products. These variables were precursor crystallinity, catalyst, and time and reaction temperature. An incr…
A high-temperature, high-pressure, tube furnace has been used to evaluate the long term stability of different monolithic ceramic and ceramic matrix composite materials in a simulated combustor environment. All of the tests have been run at 150 psia, 1204°C, and 15 percent steam in incremental 500 h runs. The major ad…
We report results on scanning force microscopy (SFM) studies of epitaxial SrBi2Ta2O9 films which, in conjunction with complementary x-ray diffraction, scanning and transmission electron microscopy data, allow us to establish direct correlation between the crystallographic structure at the submicrometer range and the n…
Die konformative Information, die in einem oligoheterocyclischen Strang aus sich wiederholenden Pyridin-Pyridazin-Kodons kodiert ist, löst einen allgemeinen Selbstorganisationsprozess aus, der zur spontanen Bildung helicaler Strukturen führt. Dabei entsteht zunächst eine helicale molekulare Einheit, die sich dann in D…
Measurement of magnetic susceptibility with temperature of a powdered iron(III) catecholate complex clearly indicated a two-step spin-crossover process S=½↔S=5/2. The picture shows the plot of χMT against temperature.
A series of 1,4-phenylene-bridged ZP-HP hybrid porphyrins (ZP = zinc porphyrin, HP = free-base porphyrin) 1-8 ZH have been prepared in which an electron-donating ZP moiety is kept constant and electron-accepting HP moieties are varied by introducing electron-accepting substituents, so that the energy gap for charge se…
The high propensity of organosilanes towards polycondensation and reaction with nucleophilic moieties has facilitated the formation of new organic-inorganic hybrids based on the lacunary divacant heteropolyanion [gamma-SiW10O36]8-. Depending on the experimental conditions two different types of derivatives were obtain…
Advantages of homo- and heterogeneous catalysts are united in metallodendritic molecules where nickel-based catalysts are bound to carbosilane dendrimers. The first direct indication of a "dendritic effect" in the redox catalysis behavior is described: variation of the dendrimer support controls the proximity of the N…