Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Novel radical addition chemistry, involving addition of CF 3 • radicals to octafluoro[2.2]paracyclophane (AF4), leads to formation of an unprecedented new class of dimeric CF 3 -substituted AF4 derivatives. These chemically stable, but highly sterically constrained compounds undergo a clean thermal homolytic retro pro…
PET-type polymers have been prepared in the presence of a variety of potential branching agents, such as trimesic acid, and with the control of branching using an end-capping agent, benzyl alcohol. The polymers synthesized have been characterized by dilute solution viscometry, end group analysis, light scattering ( M̄…
The influence of the characteristic nanostructure of semicrystalline polymers on the segmental dynamics has been studied by dielectric spectroscopy (DS) in poly(ethylene naphthalene-2,6 dicarboxylate) (PEN) samples with different degree of crystallinity. In the investigated temperature range (from −100 to +200 °C), th…
Libraries of liquid-phase catalyst precursor solutions were printed onto iridium-coated silicon substrates and evaluated for their effectiveness in catalyzing the growth of multiwalled carbon nanotubes (MWNTs) by chemical vapor deposition (CVD). The catalyst precursor solutions were composed of inorganic salts and a r…
The epoxidation of alkenes with 30% aqueous hydrogen peroxide is catalyzed efficiently by methyltrioxorhenium (MTO) in the presence of pyridine additives. The addition of 1-10 mol % of 3-cyanopyridine increases the system's efficiency for terminal and trans-disubstituted alkenes resulting in high isolated yields of th…
Correlations between intermolecular forces and ultrafiltration measurements for a thin polysulfone film and membranes modified for increased hydrophilicity by graft polymerization of 2-hydroxyethyl methacrylate and a model protein (hen egg-white lysozyme, Lz) suggest that altering either the chemistry of the polymer s…
Lattice-matched ZnCdSe 2 concentric epilayer shells up to 50 Å in thickness have been grown on InP core quantum dots (QDs). The quality of the epitaxially grown shells was monitored by absorption and emission spectra and transmission electron microscopy (TEM). Shell growth was shown to be controllable and was consiste…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTA Catalytic-Assembly Solvothermal Route to Multiwall Carbon Nanotubes at a Moderate TemperatureYang Jiang, Yue Wu, Shuyuan Zhang, Cunyi Xu, Weichao Yu, Yi Xie, and Yitai QianView Author Information Department of Chemistry and Structure Research Laboratory University of…
The mixed manganite-cuprate CaCu3Mn4O12 is found, using density functional methods, to be a narrow gap (90 meV calculated) ferrimagnetic semiconductor. Cu (formally S=1/2) antialigns with Mn (formally S=3/2), and the net spin moment is 9 μ_B consistent with the formal spins. Holes have Cu d_{xy}-O p_σ (i.e. antibondin…
Two state-of-the-art computational approaches: quantum Monte Carlo (QMC), based on accurate total energies, and GW with exciton effects (GW-BSE), based on perturbation theory are employed to calculate ionization potentials, electron affinities, and first excited singlet and triplet energies for the silane and methane…
A needle trap device (NTD) and commercial poly(dimethylsiloxane) (PDMS) 7-microm film thickness solid-phase microextraction (SPME) fibers were used for the sampling and analysis of aerosols and airborne particulate matter (PM) from an inhaler-administered drug, spray insect repellant, and tailpipe diesel exhaust. The…
The low-temperature behavior of the selective catalytic reduction (SCR) process with feed gases containing both NO and NO 2 was investigated. The two main reactions are 4NH 3 + 2NO + 2NO 2 → 4N 2 + 6H 2 O and 2NH 3 + 2NO 2 → NH 4 NO 3 + N 2 + H 2 O. The “fast SCR reaction” exhibits a reaction rate at least 10 times hi…
Clinopyroxenes from the Campiglia Marittima skarn range from hedenbergite to johannsenite (Jh(7) to Jh(100)) Twenty single-crystals were selected for structural refinements and electron microprobe analyses. (100) twins were present acid treated using a halved data set. End-member johannsenite is best approximated by t…
International audience
The amino-derivatized cyclotriveratrylene analogue, triaminotrimethoxytribenzocyclononene [CTV(NH2)3(OMe)3], 1, is readily converted into triply substituted imine compounds [CTV(sal)3(OMe)3], 2, in high yield by treatment of the acid salt of 1 with a variety of substituted salicylaldehydes. Cleavage of the protecting…
In connection with a study aimed at the evaluation of electronic effects in spiro-dicorrole (1a) and its binuclear Ni(II) complex (1b) we became interested in gem-dimethyl-substituted cyclotetrapyrrole (2a) and the corresponding Ni(II) complex (2b). Attempts to prepare 2a as the 12,13,16,17-tetraethyl-2,3,7, 8-tetrame…
One of the few examples of molecules with D3 symmetry is the novel P8Se3 cage molecule (see structure). This species was obtained as an adduct to copper iodide. This phosphoselenide cage can be formally derived from the polyphosphide “ufosane” P113− through the substitution of P− by Se.
This paper proposes a general strategy to define molecular orbitals which are especially adapted to the calculation of the energy difference between two states. These orbitals are shown to be eigenvectors of blocks of the difference between the density matrices relative of the two states. They may be used for rational…
Die eindimensionale Ausbreitung eines Multiporphyrinaggregates auf eine Länge von einigen Hundert Nanometern wurde durch die mehrfache komplementäre Koordination eines Imidazol-substituierten Bis-Zinkporphyrins erreicht (siehe Bild). Die Länge des Aggregats hängt zum einen vom Lösungsmittel ab und kann zum anderen dur…
Picosecond to submillisecond photochromic reactions of 2,4-diphenyl-2H-benzopyran and 2,2,4-triphenyl-2H-benzopyran have been investigated by time-resolved absorption spectroscopy. The C−O bond cleavage of the benzopyrans (closed forms) occurs via the first excited singlet state within 2 ps to produce vibrationally ex…