Materials Literature
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It has recently been shown that amorphization and melting of ice (O. Mishima, Nature , 384 (1996) 546) were intimately linked. In this letter, we infer from molecular-dynamics simulations on the SiO 2 system that the extension of the α-quartz melting line in the metastable pressure-temperature domain is the pressure-i…
The possibility of determining the temperature of diamond by noncontact Raman spectroscopy is assessed critically. The intensity ratio of Stokes to anti-Stokes lines is shown to be ill suited for temperatures above ∼750 K. Employing the temperature coefficient of the Raman line position, on the other hand, turns out t…
We consider the low-energy magnetic excitations of nanographite ribbons with zigzag edges. The zigzag ribbons possess almost flat bands at the Fermi level which cause a ferrimagnetic spin polarization localized at the edge sites. The spin wave mode of this magnetic state is investigated by a random phase approximation…
Electroluminescence (EL) and photoluminescence (PL) from heterostructure thin films made of organic poly (phenylene vinylene), PPV, and inorganic semiconductor CdSe nanocrystals are investigated. In these devices, the organic PPV structure is built next to an indium tin oxide anode, using the technique of molecular la…
Significant reductions in both the in-plane and cross-plane thermal conductivities of superlattices, in comparison to the values calculated from the Fourier heat conduction theory using bulk material properties, have been observed experimentally in recent years. Understanding the mechanisms controlling the thermal con…
The 3p photoelectron spectra of atomic Fe and Cu, and the Fe outer-shell satellites have been investigated. The complex multiline structure of the Fe spectra has been resolved using high-resolution electron spectroscopy. The thresholds of the direct 3p photoionization have been determined and are compared with experim…
Crosslink dissociation of resole-cured NR vulcanizates was studied using steam aging. Four carbon black-filled NR vulcanizates were prepared to investigate the influence of heated p-t-octylphenol formaldehyde resole (at 160°C for 0.0, 1.5, 3.0, and 6.0 h) on the cure characteristics and stability of the crosslinks. By…
Liquid−liquid equilibria and separation factors for the systems m -cresol + o -toluonitrile + hexane + water + (glycerol or triethylene glycol) have been determined at 313.15 K in order to evaluate their suitability in separating m -cresol from o -toluonitrile. The effects of parameters such as the type of high-boilin…
To obtain an optical polymer with a high refractive index (nD) and Abbe's number (νD), a series of 1,4-dithiane-2,5-bis(thiomethyl) (DBT) group-bearing poly(S-alkylcarbamate) and polyvinylsulfide were synthesized by the polyaddition of 2,5-bis(mercaptomethyl)-1,4-dithiane (BMMD) with diisocyanates and by the addition…
GeX 2 ·dioxane (X = Cl, Br) complexes insert completely into CBr 4 to afford the sterically crowded cluster compounds (BrCl 2 Ge) 4 C ( 1 ) and (Br 3 Ge) 4 C ( 2 ) in 80% and 95% yields, respectively. These display physical, spectroscopic, and structural properties that are indicative of highly symmetric molecules wit…
Large-amplitude oscillatory shear (LAOS) has been applied to a lamellar, microphase-separated, low molecular weight poly(styrene- b -isoprene) diblock copolymer melt to induce macroscopically aligned morphologies. Small-angle X-ray scattering and dynamic mechanical testing were performed to characterize the states of…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHigh-Frequency EPR Spectroscopy of Large Metal Ion Clusters: From Zero Field Splitting to Quantum Tunneling of the MagnetizationAnne-Laure Barra, Louis-Claude Brunel, Dante Gatteschi, Luca Pardi, and Roberta SessoliView Author Information Laboratoire des Champs Magnetiques I…
The procedure of aggregate-free poly(vinyl chloride) (PVC) solutions for size-exclusion chromatography (SEC) at room temperature using tetrahydrofuran (THF) as the mobile phase is proposed. PVC was dissolved in 1,2,4-trichlorobenzene (TCB) at 130 or 140°C for 6 h, precipitated in methanol, filtrated, and dried. The pr…
Detonation-synthesized nanodiamonds (5 nm in diamenter, containing 10% O as defects) decompose violently when irradiated by pulsed Nd:YAG laser photons at 1064 nm. The irradiation shatters the diamond lattice via multiphoton excitation, yielding CO and CO2 in the gas phase and graphitic spheroidal nanoparticles on the…
Polyaniline (PANI) was doped with p-phenolsulfonic acid (PSA) or 5-sulfosalicylic acid (SSA). The PANI salts were blended with poly(N-vinyl-2-pyrrolidone), poly(N-methyl-N-vinylacetamide), poly(N,N-dimethylacrylamide), or poly(2-methyl-2-oxazoline) by solution casting from dimethyl sulfoxide. Blends containing up to 5…
Three generations of dendrimers with a fluorescent core were synthesized by attaching dendrons of the Fréchet type to a dihydropyrrolopyrroledione (DPP) molecule. Samples were prepared by spin-coating a toluene solution containing 2 × 10 -9 M of the dendrimers and 3 mg/mL polystyrene (MW 45 000) on a glass cover slip.…
The grafting of polymers having controlled molecular weight and narrow molecular weight distribution onto chitosan powder by the termination of living polymer cation with amino groups on chitosan powder was investigated in heterogeneous system. The amino groups of chitosan powder successfully reacted with living poly(…
Three structurally variant alkyl-substituted porphyrins [zinc(II) 2,3,7,8,12,13,17,18-octa- n -decylporphyrin 2, metal(II) meso -5,10,15,20-tetra- n -undecylporphyrin 3 (metal = cobalt, copper, palladium, and zinc), and zinc(II) meso -5,10,15,20-tetrakis(phenoxy- n -nonyl)porphyrin 4] exist as photoconductive insulato…
The mechanical properties of recycled low-density polyethylene/wood flour (LDPE/WF) composites are improved when a maleated triblock copolymer styrene–ethylene/butylene–styrene (SEBS–MA) is added as a compatibilizer. The composites' tensile strength reached a maximum level with 4 wt % SEBS–MA content. The compatibiliz…
Strontium clusters of size 2 to 20 atoms have been studied within the local density approximation using the ab-initio molecular dynamics method with a plane wave basis in which the s and p electron wavefunctions are well represented. The resulting low lying isomers are optimized using a full-potential linear muffin ti…