Materials Literature
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The kinetics of the enzymatic degradation of bacterial poly(3-hydroxybutyrate) (PHB) is studied using PHB-depolymerase A from Pseudomonas lemoignei (Tris−HCl buffer, pH = 8, T = 37 °C). Biodegradation experiments are performed on PHB in the form of both compression-molded films and powder suspension. From WAXS and DSC…
We compute phase diagrams for A n B m starblock copolymers in the strong-segregation regime as a function of volume fraction φ, including bicontinuous phases related to minimal surfaces (G, D, and P surfaces) as candidate structures. We present the details of a general method to compute free energies in the strong seg…
We consider surfaces protected by polymer chains of N monomers grafted at a density σ, that are immersed in a melt of chemically similar chains of polymerization index P . We have used the self-consistent field approximation to analyze the practically useful (but analytically untractable) case of moderately long melt…
We study the dependence of the intramolecular M I −M I interaction on electron correlation effects in eight-membered rings of type [M 2 (PH 2 CH 2 PH 2 ) 2 ] 2+, [M 2 (NHCHNH) 2 ], [M 2 (SCHS) 2 ] (M = Au, Ag, Cu), [Au 2 (PH 2 CH 2 PH 2 ) 2 ]Cl 2, halogenometal(I) [M 2 X 4 ] 2 - (M = Au, Ag, Cu; X = Cl, Br, I), and [A…
The cloud points of various amorphous polyether, polyacrylate, and polysiloxane homopolymers, and a variety of commercially available block copolymers, were measured in CO 2 at temperatures from 25 to 65 °C and pressures of ca. 1000−6000 psia. Almost without exception, the solubility of amorphous polymers increases wi…
The effect of specific ionic interactions on the Debye length has been studied using a simple model Hamiltonian for a binary mixture of anions and cations in the framework of the field theory. The Hamiltonian contains the Coulombic interaction and an independent non-Coulombic part describing a binary mixture of equiva…
The orientation and the axial, Deltachiax, and rhombic, Deltachirh, components of the magnetic susceptibility tensor anisotropy for the cobalt(II) and nickel(II) derivatives of azurin from Pseudomonas aeruginosa have been determined from 1H NMR data. For both derivatives, the axial geometry of the system determines th…
We have conducted a first principles density functional theory (DFT) calculation to explore the electronic structure of sodalite at various stages of Al-substitution. By calculating the electronic structure of both substituted and unsubstituted frameworks, with and without the presence of extra-framework atoms, we sho…
The conformational properties of five gadolinium(III) complexes with polyamino carboxylate (PAC) ligands used as magnetic resonance imaging contrast agents have been investigated by ab initio and molecular mechanics (MM) methods. Ab initio calculations were performed using an effective core potential (ECP) that includ…
The concentration at the interface of a growing or dissolving crystal has been previously found experimentally to be different from the equilibrium value; however, a method for predicting this concentration has not been available. We report an investigation that uses statistical rate theory to obtain the expression fo…
The methionine analogue 2-amino-5-hexenoic acid (homoallylglycine, Hag) can be utilized by Escherichia coli in the initiation and elongation steps of protein biosynthesis. Use of an E. coli methionine auxotroph and Hag-supplemented medium resulted in replacement of ca. 85% of the methionine residues in mouse dihydrofo…
Comprised of ferromagnetic edge-sharing CuO$_2$ chains that order in antialigned fashion at T$_N$=9 K, Li$_2$CuO$_2$ is found from local spin density calculations to display several surprising characteristics: (1) the ordered moment/f.u. of 0.92 $μ_B$ is the largest for any low dimensional cuprate system, in agreement…
An explanation of the anomalous concentration dependence of diffuse scattering from the Pt-V alloy system (splitting of the (100) short-range order intensity peak with increasing Pt content) is proposed. The effect is attributed to the competition between the interaction and self-energy curvatures. A similar temperatu…
We present a first-principles calculation of the electronic properties of crystalline silicon and gallium arsenide in a uniform electric field. Polarized Wannier-like functions which are confined in a finite region are obtained by minimizing a total-energy functional which depends explicitly on the macroscopic polariz…
Pore volumes, accessible surface areas, and the thermodynamics of adsorption are essential in the understanding of solid surface characteristics fundamental to catalyst and adsorbent screening and selection. The recently developed Multiple Equilibrium Analysis (MEA) provides a thorough characterization of the adsorpti…
The dissipative particle dynamics (DPD) simulation method has been used to study mesophase formation of linear (AmBn) diblock copolymer melts. The polymers are represented by relatively short strings of soft spheres, connected by harmonic springs. These melts spontaneously form a mesocopically ordered structure, depen…
Single-wall fullerene nanotubes were converted from nearly endless, highly tangled ropes into short, open-ended pipes that behave as individual macromolecules. Raw nanotube material was purified in large batches, and the ropes were cut into 100- to 300-nanometer lengths. The resulting pieces formed a stable colloidal…
The relationship between the fraction of material removed and the degree of penetration often observed in the literature during single-particle grooving tests on metals is examined in terms of low cycle fatigue. It is shown that the fraction of material removed is closely related to the low cycle fatigue behaviour of…
A new ordering scheme in cationic-deficient perovskite-like phases of the Ba n (Mo,Nb) n - δ O 3 n - x system has been described for the composition Ba 3 MoNbO 8.5, which has an oxygen stoichiometry between those of the 9R polytype and the palmierite structure. An electron diffraction and high-resolution electron micr…
A new chemical and electrochemical synthesis of the linear tetranuclear manganese complex, [Mn 4 IV O 6 (bpy) 6 ] 4+ (bpy = 2,2‘-bipyridine) ( 4 ) is described. This complex can be synthesized by a two-electron oxidation of an aqueous solution of the mononuclear [Mn II (bpy) 3 ] 2+ ( 1 ) one. The aqueous solutions wer…