Materials Literature
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We demonstrate that a staggered parametric ac driving term can support stable progressive motion of a soliton in a Toda lattice with friction, while an unstaggered drivng force cannot. A physical context of the model is that of a chain of anharmonically coupled particles adsorbed on a solid surface of a finite size. T…
Nano-crystalline diamond is prepared with a unique method in which a graphite target is etched by a high-power pulsed laser in water. Transmission electron microscopy (TEM) and high resolution electron microscopy (HREM) indicate nano-crystalline diamond is obtained, having a hexagonal lattice or cubic lattice.
Triethoxysilane HSi(OEt)3 was used as coupling agent to graft a poly(organophosphazene) (POPZ) containing allylic functions to the surface of poly(vinyl alcohol) or poly(ethylene-co-vinyl alcohol) films. Hydrolyzed HSi(OEt)3, which contained both inorganic (Si–OH) and organic (Si–H) reactivities, acted at the interfac…
The preparation of a novel triaryl phosphine oxide thermoset polymer containing the perfluorocyclobutane linkage is described. The synthetic methodology involves the formation of a Grignard reagent from 4-bromotrifluorovinyloxybenzene and reaction with phosphorous trichloride to form the triaryl phosphine trifluorovin…
Composites were made from rubberwood in the form of fibers (RWF) and powder (RWP) and high-density polyethylene (HDPE). The RWP–HDPE composites showed higher tensile strength than those of the fibers. The inferior properties of the RWF-filled composites were believed to be attributed to the agglomeration of the fibers…
The isothermal and nonisothermal crystallization kinetics of nonnucleated and nucleated isotactic polypropylene (iPP) were investigated by DSC and a polarized light microscope with a hot stage. Dibenzylidene sorbitol (DBS) was used as a nucleating agent. It was found that the crystallization rate increased with the ad…
A new type of bamboo fiber-reinforced polypropylene (PP) composite was prepared and its mechanical properties were tested. To enhance the adhesion between the bamboo fiber and the polypropylene matrix, maleic anhydride-grafted polypropylene (MAPP) was prepared and used as a compatibilizer for the composite. The maleic…
Selective formation of trans-nitrochlorins 16-19, cyclopropylchlorins 14, 15, and 20-23, or functionalized trans-chlorins 5-13 by reaction of 2-nitro-5,10,15,20-tetraphenylporphyrin 1 with "active" methylene compounds such as malonates or malononitrile in the presence of base has been achieved. Reaction control is acc…
Highly porous matrices of poly-L-lactide (PL) and polyglycolide (PG), 24, 50, or 95 mg/cc in the form of 10 x 10 x 3 mm wafers, were implanted subcutaneously (two per rat) in the flanks of 8-12-week-old female Lewis rats (n = 120). Matrices were harvested, two rats per week, for 15 weeks and examined histologically. A…
Previous studies demonstrated that poly(DTE carbonate) and poly (DTE adipate), two tyrosine-derived polymers, have suitable properties for use in biomedical applications. This study reports the evaluation of the in vivo tissue response to these polymers in comparison to poly(L-lactic acid) (PLLA). Typically, the bioco…
Primary human osteoblasts were cultured on self-assembled monolayers (SAMs) of alkylthiols on gold with carboxylic acid and methyl termini, and the kinetics of cell attachment and proliferation were measured. Over 90 min approximately twice as many cells attached to carboxylic-acid-terminated monolayers as attached to…
Understanding the relationships between material surface properties, adsorbed proteins, and cellular responses is essential to designing optimal material surfaces for implantation and tissue engineering. In this study, we have prepared model surfaces with different functional groups to provide a range of surface wetta…
The growth of polypyrrole was modeled by transition state calculations and by evaluation of frontier orbital interactions for the successive coupling reactions to form the polymer (the HOMO of the transition state for the coupling of two pyrrole radical cations is shown on the right). The predicted growth trend for po…
Complexation of metal ion and counterion by the same compound is possible with zirconium meso-octaalkylporphyrinogens (structure of a dimeric complex with four encapsulated equivalents of LiH is depicted): they carry salts in the molecular ion-pair form in hydrocarbons, and function as acid-base bifunctional compounds.
25 nm2 groß sind die quadratischen Porphyringitter des Typs 1, die durch Selbstorganisation aus einundzwanzig Komponenten gebildet werden: aus je vier Di- und Tripyridylporphyrinen, einem Tetrapyridylporphyrin sowie zwölf {PdCl2}-Einheiten.
A rich diversity of structural motifs have been uncovered in a family of crown-ether-coordinated alkali metal pyridine-2-thiolates, featuring a templated dimer and polymer (depicted below), an asymmetrically coordinated monomer, and an unprecedented separated ion quadruple with two unusual sodium metalates. Crown ethe…
The structural flexibility of [Cp2M(dithiolene)] complexes (M=Mo, W; dithiolene=dmit2−, dmid2−, dsit2−; the [CpMo(dmid)] complex is depicted on the right) is manifested in various folding angles of the MS2C2 metallacycle in a series of charge-transfer salts with TCNQF4. The evolution of the electronic structures with…
Replacing the 3- and 3′′-protons of the ligand 2,6-di(pyrazol-1-yl)pyridine L by mesityl groups changes the electronic ground state of [Cu(L)2]2+ complexes from {d}1 to {d}1. This is the best example so far for a “homoleptic” Jahn–Teller-compressed six-coordinate CuII complex.
A three-component array consisting of a free-base arylporphyrin and a gold(III) arylporphyrin, assembled together with a central bis(terpyridine)ruthenium(II) complex (right), has been synthesized, and the photophysical properties determined. The observed room-temperature prevalence of photoinduced energy transfer wit…
A spiro attack on a peroxo group is calculated to be the preferred reaction pathway for olefin epoxidation with the catalytic system CH3ReO3/H2O2 (see picture). This finding is supported by density functional calculations on more than ten transition states for the most probable mechanisms. Hydration has significant ef…