meso-Tetraarylporphyrins as dipolarophiles in 1,3-dipolar cycloaddition reactions
meso-Tetraarylporphyrins participate, as dipolarophiles, in 1,3-dipolar cycloaddition reactions with azomethine ylides to yield novel chlorins and isobacteriochlorins.
Materials Literature
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Molecular Weight Distribution of Hyperbranched Polymers Generated by Self-Condensing Vinyl Polymerization in Presence of a Multifunctional Initiator
The molecular weight distribution (MWD) is derived for polymers generated by self-condensing vinyl polymerization (SCVP) of a monomer having a vinyl and an initiator group (“inimer”) in the presence of a multifunctional initiator. If the monomer is added slowly to the initiator solution (semi-batch process), this lead…
Factors affecting initial permeability of Co-substituted Ni-Zn-Cu ferrites
Iron deficient compositions of (Ni/sub 0.2/Cu/sub 0.2/Zn/sub 0.6/)/sub 1.02x/Co/sub x/Fe/sub 1.98/O/sub 4/ (0/spl les/x/spl les/0.05) were prepared to investigate their initial permeability dependence on cobalt contents. Extrinsic factors such as grain size and sintered density change little in samples sintered at 900…
Subchromophore interactions in tricyanovinyl-substituted triarylamines—a combined experimental and computational study
The electronic coupling between the phenyl substituents of mono-, bis-, and tris(tricyanovinyl)-substituted triphenylamines (1, 2, 2-OMe and 3) have been investigated by various methods: the splitting of excited states was taken as a measure of the interaction. These splittings can be seen in the optical absorption sp…
Contribution of shape resonance and Pt–H EXAFS in the Pt L2,3 X-ray absorption edges of supported Pt particles: Application and consequences for catalyst characterization
The electronic and geometric effects induced by hydrogen chemisorption on small platinum particles supported on high surface-area saponite clay and zeolite LTL were studied by near edge X-ray absorption fine structure (XAFS) spectroscopy. A new subtraction procedure was developed to separate the electronic from geomet…
Three-Phase Planar Eutectic Growth Models for a Ternary Eutectic System
In order to consider a phase selection in a ternary eutectic system, analytical expressions for three-phase planar eutectic growth have been derived, assuming the geometries as regular, rod+hexagon and semi-regular types. Irrespective of geometries the relations that the undercooling is proportional to the square root…
Characterization of homogeneous ethylene/1‐octene copolymers made with a single‐site catalyst. CRYSTAF analysis and calibration
The crystallizability of narrow composition, homogeneous ethylene/1-octene copolymers made with a constrained geometry catalyst, measured by CRYSTAF, follows a straight line correlation with the amount of total comonomer incorporated. The potential use of these resins as standards to calibrate CRYSTAF and TREF techniq…
Local chain ordering in amorphous polymer melts: influence of chain stiffness
Molecular dynamics simulation of a generic polymer model is applied to study melts of polymers with different types of intrinsic stiffness. Important static observables of the single chain such as gyration radius or persistence length are determined. Additionally we investigate the overall static melt structure includ…
Modeling of electromagnetic phenomena in soft magnetic materials under unidirectional time periodic flux excitations
We report on recent advances in the modeling of magnetic losses in steel laminations used in electromagnetic devices. The integrated-lamination moving dynamic Preisach model, used to evaluate the dynamic magnetization loops under distorted unidirectional flux patterns, is described. The main goal is the comparison of…
Micromixing in a single‐feed semi‐batch precipitation process
Abstract A mixing‐precipitation model (based on engulfment, the E‐model by Baldyga and Rohani, 1987) is applied to a single‐feed semi‐batch precipitation process to describe the mixing effects on the final particle‐size distribution (PSD) and particle morphology. The model describes mixing on two scales: the microscal…
New catalysts for the aerobic selective oxidation of hydrocarbons: Mn(III)- and Co(III)-containing molecular sieves for the epoxidation of alkenes
Co(III) or Mn(III) ions that replace some 4 atom% of Al(III) sites in microporous aluminophosphate number 36 (AlPO-36) function as catalytically active centres for the production from benzaldehyde of acylperoxy radicals: these, in turn, in dry air (30 bar) convert cyclohexene, pinene, limonene and styrene to their cor…
Hybrid organic-inorganic layered compounds prepared by anion exchange reaction: correlation between structure and magnetic properties
The synthesis, structure and magnetic properties of a series of hybrid organic-inorganic copper(II) compounds are reported. Anion exchange reactions were used to prepare layered materials made of copper(II)-based inorganic layers separated by long chain anions (n-alkyl sulfates or n-alkyl carboxylates). Contrary to cl…
Considerations of defect equilibria in high temperature proton-conducting cerates
Acceptor doped perovskites such as strontium cerate form a variety of point defects through reaction with surrounding gases at high temperature, namely protons by dissolution of water vapour, electron holes by dissolution of oxygen and electrons by loss of oxygen. The defect equilibria can be described by three equili…
Sculptured thin films—II. Experiments and applications
A report on the preparation and potential applications of sculptured thin films (STFs) is presented. STFs are nano-engineered columnar thin films in which the columnar direction can made to change easily and often during growth. STFs of virtually any material can be prepared through directional vapor deposition onto a…
Solidification Phase and Microstructure Selection Maps for Fe-Cr-Ni Alloys.
Directional solidification and laser experiments have been performed in Fe-18.0%Cr-Ni alloys to evaluate the effects of alloy composition and growth velocity on microstructure and phase selection. Solidification microstructure selection maps are described by microstructure (dendrite/cell, plane front and eutectic) mod…
Photochromic flavylium compounds as multistate/multifunction molecular-level systems
Synthetic flavylium compounds can exist in several forms (multistate) that can be interconverted by more than one type of external stimulus (multifunctional). The intricate network of their reactions, when examined from the view point of ‘molecular-level devices’, reveals very interesting properties.
Synthesis and structural investigations of the double perovskites REBaFe2O5+w (RE=Nd, Sm)
By selection of appropriately sized rare earth elements and suitable reaction atmosphere, a new double-perovskite-type iron oxide REBaFe 2 O 5+ w (RE=Nd and Sm) has been synthesized, with, ideally, all Fe atoms in square-pyramidal coordinations when w=0. Like in the related triple-perovskite-type YBa 2 Fe 3 O 8+ w ′ ,…
Interactions between a Macrophage Cell Line (J774A1) and Surface-modified Poly(D,L-lactide) Nanocapsules Bearing Poly(ethylene glycol)
The interactions of naked and surface-modified poly(D,L-lactic acid) (PLA) nanocapsules (NC), where polyethyleneglycol (PEG) was adsorbed or covalently attached, have been studied with a macrophage-like cell line. The fluorescent oil marker, DiD, was successfully encapsulated in NCs in order to follow their interactio…
Anodic and cathodic electrografting of alkynes on porous silicon†
A versatile electrochemical grafting reaction connects conjugated molecules to porous silicon surfaces with either a positive or negative bias.
Modified Johnson-Cook model for vehicle body crashworthiness simulation
Dynamic response prediction of vehicle bodies is important for vehicle crashworthiness evaluation. The dynamic behaviour of vehicle body materials is dependent on material strain rates. One of the typical high strain rate tensile tests is the split Hopkinson bar test. In this paper, experiments have been conducted bas…