Materials Literature
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BACKGROUND: The alkaline protease from Pseudomonas aeruginosa (AprA) is a member of the metzincin superfamily of metalloendoproteases. A key feature of these proteases is a conserved methionine-containing 1,4-tight beta turn at the base of the active site zinc binding region. RESULTS: To explore the invariant methioni…
A network of screw dislocations was artificially created in SrTiO3, and characterized by transmission electron microscopy (TEM). Slight expansion of the dislocation core was observed by TEM. The composition of the dislocation core was quantified by electron energy loss spectroscopy, which reveals a 13±5% Ti∕O ratio in…
A single step sol-gel process was used to precipitate silica microspheres containing ibuprofen or naproxen for controlled drug delivery applications. The drug release behavior from these systems was analyzed in vitro. Pure ibuprofen and naproxen exhibited linear release with time, while sol-gel silica entrapped drugs…
Abstract The first example of a porphyrin‐quinonoid donor–acceptor triad featuring (tetraphenylporphinato)zinc( II ) moieties covalently attached to an oxoporphyrinogen through its macrocyclic nitrogen atoms is reported. This arrangement of chromophores results in an interesting interplay between the electron‐donating…
Längst überfällig: Die Kristallstruktur der metastabilen Form von Benzamid (siehe Bild), deren Existenz seit über 170 Jahren bekannt war, ist endlich aufgeklärt worden – durch eine Kombination von In-situ-Kristallisation, Hochgeschwindigkeits-Synchrotronröntgenpulverbeugung und globalen Optimierungsmethoden zur Strukt…
One of the essential parts in the molecular mechanism of biological properties is the structural changes of proteins induced by stimuli. An amphiphilic copolymer, poly(L-leucine) grafted polyallylamine as a simple model of proteins, has been prepared by NCA polymerization with free amino groups of polyallylamine as an…
Abstract An overview is given on the electronic and optical properties of Si and Ge nanocrystals. We model free‐standing Si and Ge nanocrystals passivated with H, with up to 363 group‐IV atoms and 276 H and oxidized nanocrystals with additional silicon oxide shells, e.g. Si 41 (O 60 Si 42 )(O 108 Si 64 )H 148 . The re…
Deformation twinning occurs in various materials including metals, intermetallics, ceramics, superconductors, and even geological systems. The rate of twin growth depends on the material system, but there are no crystallographic models to understand the mechanisms of slow twin growth. The physics of twin growth is pre…
The a.c. conductivity σa.c(ω), the dielectric constant ϵ′ and dielectric loss ϵ″ of polycarbonate sheet have been studied in the frequency range 1.5 × 102–5 × 106 Hz and temperature range 294–473 K. A.c. conductivity σa.c(ω) results show that it depends strongly on the frequency and slightly on the temperature, with a…
Pd black was exposed to ethylene alone or in its mixture with hydrogen at 300 and 573 K. The samples were investigated by X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). Room temperature introduction of C(2)H(4) (also in the presence of H(2)) induced a binding-energy (BE) shift…
Abstract The aqueous solubility S w and 1‐octanol–( P o ), cyclohexane–( P ch ), and chloroform–( P cf ) water partition coefficients are calculated. The properties of single‐wall carbon nanotubes (SWNT) are related to the indices ( n, m ) designating the chiral vector. SWNTs are classified in zigzag ( n , 0), armchai…
We have performed Monte Carlo simulations to reproduce the intrinsic viscosity corresponding to different generation of several types of dendrite molecules: polyamidoamine dendrimers with an ethylendiamine core, polypropylene-imine with a diaminobutane core, and monodendrons and tridendrons of polybenzylether. With th…
Crystal growth of inorganic materials, calcium carbonate, barium sulfate, and calcium oxalate, was studied in the presence of calix[4]arene additives functionalized with aspartic or glutamic acids at the lower rim. The additives were synthesized by reaction of the appropriate amino acid ester with 5,11,17,23-tetra- te…
To study molecules able to act as good "molecular wires", intramolecular electron transfer between two triphenylmethyl redox centers connected by bridges with different topologies and substituents have been studied in solution, both by UV-Vis-NIR and EPR spectroscopies. The synthetic methodology used allows a complete…
The interaction of streptavidin (SA) with a biotinylated surface has been of great interest in the development of an interfacial layer for protein immobilization based on self-assembled monolayers (SAMs) and polymeric layers. Here, we demonstrate the unique characteristics of protein-ligand interactions on dendrimer m…
In a series of ferroelastic urea inclusion compounds (UICs), in which domain reorientation occurs upon application of an external anisotropic force, introduction of a relaxive impurity that disrupts a specific hydrogen-bonding network transforms a plastic (irreversible) domain-switching process into one that exhibits…
Abstract In supramolecular systems, the interaction between different units modulates their photophysical properties. a) For platinum( II ) complexes with ligands that have extended π systems, π‐stacking and direct metal–metal interactions result in the formation of excimers with characteristically red‐shifted lumines…
We analyse the possible phase diagrams of a simple model for an associating liquid proposed previously. Our two-dimensional lattice model combines orientational ice-like interactions and `van der Waals' interactions which may be repulsive, and in this case represent a penalty for distortion of hydrogen bonds in the pr…
The subphase for the temperature range that lies in between $\mathrm{Sm}\text{\ensuremath{-}}{C}_{A}^{*}$ and the three-layer $\mathrm{Sm}\text{\ensuremath{-}}{C}_{A}^{*}(1∕3)$ subphase has been confirmed to exist using the measurements of electric-field-induced birefringence, optical rotation, and the characteristic…
Two new polymorphs of BiB3O6 were identified at low temperatures using boric acid as a flux. Unlike alpha-BiB3O6, which crystallizes in a noncentrosymmetric space group and, thus, shows exceptional nonlinear optical (NLO) properties, beta-BiB3O6 (I) and gamma-BiB3O6 (II) crystallize in the centrosymmetric space group…