Materials Literature
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Polyhydroxyalkanoates (PHAs) are microbial polyesters that can be used as completely biodegradable polymers, but the high production cost prevents their use in a wide range of applications. Recombinant Escherichia coli strains harboring the Ralstonia eutropha PHA biosynthesis genes have been reported to have several a…
The design and synthesis of new linear-dendritic diblock copolymers with a linear PEO block and a dendrimeric PAMAM block are described. Two series with PEO molecular weights of 2000 and 5000 were synthesized. DSC results on the effect of diblock composition on the microphase segregation behavior of the diblocks are r…
Organic vapor phase deposition (OVPD) opens new opportunities in the control of composition and structure of organic thin films. The use of this recently developed process is examined for the growth of four archetypal organic systems: a crystalline organic salt (the optically nonlinear charge transfer salt DAST, see F…
Among organic photochromic compounds (attractive for optical data storage) diarylethenes are of special interest as switching units. They undergo a reversible electrocyclic interconversion between a colorless, non-conjugated open state (see Figure) and a colored, conjugated closed state. The design and synthesis of di…
Silver ions are reduced in aqueous solutions that contain sodium polyacrylate or partly carboxylated polyacrylamide or glutaric acid. The reducing agent is the hydrated electron (generated γ-radiolytically) or hydrogen. Complexes of small silver clusters with the polyelectrolyte are formed in the early stages of reduc…
This work presents a comparative study of structural and aerodynamic properties of cellular ceramics prepared by two different techniques: the ceramic replication of an organic substrate and the gelcasting of foams. Permeability constants calculated from Ergun's equation were related to their apparent porosity and por…
Ferroelectric thin films of bismuth‐containing layered perovskite Bi 4 Ti 3 O 12 have been fabricated by a metalorganic decomposition (MOD) method. Crack‐free and crystalline films of ∼5000 Å thickness have been deposited on Pt/Ti/SiO 2 /Si substrates. Different heat treatments have been studied to investigate the nuc…
A quantitative study of hole-transfer superexchange in Class II mixed-valence complexes is presented. The free energy of resonance exchange was calculated from metal−metal coupling elements derived from Hush and CNS models and compared to experimental values that were factored from the free energy of comproportionatio…
A highly efficient luminescent material is produced from a 2,2′-bipyridine-lanthinide-ion coordination complex. The authors describe how this coordination complex can be stabilized by ethylene glycol oligomers. The material, obtained by simple mixing of the components, emits blue, green, and red photoluminescence by s…
The properties of lead zirconate titanate (PZT) ceramics are determined by the microstructure and chemical homogeneity of Zr, Ti, and dopants within the grains as well as the presence of secondary grain boundary phases. Stoichiometric 53/47 PZT and compositions with 3 mol% PbO excess were prepared by the mixed‐oxide p…
The relative stabilities of the unknown larger closo-borane dianions B(n)()H(n)()(2)(-) (n = 13-17), were evaluated at the B3LYP/6-31G level of density functional theory by comparing the average energies, E/n, and also by the energies using the model equation: B(n)()(-)(1)H(n)()(-)(1)(2)(-) + B(6)H(10) --> B(n)()H(n)(…
The refractive index increment of a protein solution is a property not only of the protein, but also of the solvent. This is demonstrated theoretically and confirmed experimentally using analytical interferometry. © 1998 John Wiley & Sons, Inc. Biopoly 46: 489–492, 1998
By using α‐ and β‐SiC starting powders with similar particle sizes, the effects of initial α‐phase content on the microstructure and the mechanical properties of the liquid‐phase‐sintered and subsequently annealed materials were investigated. The microstructures developed were analyzed by image analysis. When β‐SiC po…
The acidity and its effects on reactivity of Keggin-type heteropolycompounds were examined by catalytic probe reactions, microcalorimetry of ammonia sorption, and density functional quantum chemical calculations. Phosphotungstic, phosphomolybdic, silicotungstic, and silicomolybdic acids were used as model compounds. T…
Abstract The plasticizing effect of glycerol and the crosslinking effect of formaldehyde and calcium chloride on the mechanical and thermomechanical properties of whey protein-based films were studied. Increased plasticizer content increased the percentage of solubility in water and decreased the mechanical resistance…
Aluminosilicate glasses containing rare-earth and rare-earth analogue cations such as Y 3+ and La 3+ are interesting for a variety of technological applications, as well as for elucidating general principles of glass formation and structure. We present high-resolution 17 O and 27 Al NMR data on a series of lanthanum a…
We probe the structure−dynamics relationship in melts of star polymers with high functionality using small-angle X-ray scattering, rheology, and Monte Carlo computer simulations. These materials represent model steric soft spheres, which order in a liquidlike structure on a macromolecular scale because of the impenetr…
Two poly(propyleneimine) dendrimers bearing up to 32 photoisomerizable azobenzene groups in the periphery have been used as potential hosts for eosin Y (2‘,4‘,5‘,7‘-tetrabromofluorescein dianion). The all- E azobenzene dendrimers can be reversibly switched to their Z form by light excitation. Both the E and Z forms of…
In agreement with previous results reported for colloidal silver clusters, effective surface-enhanced Raman cross sections of about 10- 16 cm 2 per molecule, corresponding to enhancement factors on the order of 10 14 , have also been obtained for molecules attached to colloidal gold clusters. Spatially isolated nearly…
A class of degradable, phase-segregated multiblock copolymers is presented. The new copoly(ester-urethane)s, termed DegraPolTM/btgc, consist of crystallizable poly[(3-R-hydroxybutyrate)-co-(3-R-hydroxyvalerate)]-segments and amorphous segments from ε-caprolactone, diglycolide and ethylene glycol. As junction unit an a…