The mechanisms of crystallization and transformation of calcium carbonates
Abstract
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Cation disorder in ferroelectric Aurivillius phases of the type Bi2ANb2O9(A=Ba, Sr, Ca)
The structures of the ferroelectric two-layer Aurivillius phases Bi 2 ANb 2 O 9 (A=Ba, Sr, Ca) have been refined using a combination of X-ray and neutron powder diffraction data. Bi 2 BaNb 2 O 9 is not significantly distorted from idealised symmetry and has been refined in tetragonal space group I4/mmm, a=3.9362(1) an…
Dense perovskite membrane reactors for partial oxidation of methane to syngas
The partial oxidation of methane to synthesis gas (syngas, CO + H2) was performed in a mixed-conducting perovskite dense membrane reactor at 850°C, in which oxygen was separated from air and simultaneously fed into the methane stream. Steady-state oxygen permeation rates for La1-xA′xFe0.8 Co0.2O3-δ perovskite membrane…
Polyelectrolyte–Surfactant Complexes in the Solid State: Facile building blocks for self‐organizing materials
Abstract Even though mixtures of polyelectrolytes and surfactants are used in a variety of technologies, little is known about the solid state properties of complexes formed by the two components. Recently reported methods for preparing polyelectrolytesurfactant complexes and their solid‐state structure will be descri…
Synthetic Biodegradable Polymer Scaffolds
This body of work represents the first volume of a book series covering the field of tissue engineering. Tissue engineering, which refers to a category of therapeutic or diagnostic products and proces
Chiral salen manganese complex encapsulated within zeolite Y: a heterogeneous enantioselective catalyst for the epoxidation of alkenes
A chiral (salen)Mn III complex [salen: trans-(R,R)-1,2-bis(salicylideneamino)cyclohexane] analogous to Jacobsen’s catalyst is prepared inside the supercages of zeolite Y, showing catalytic activity very similar to that of the chloride complex in the homogeneous phase.
Diffusing-wave-spectroscopy measurements of viscoelasticity of complex fluids
We present a new use of dynamic light scattering that permits the determination of the viscoelastic behavior of a complex fluid. By describing the motion of a scattering particle in a viscoelastic medium in terms of a generalized Langevin equation with a memory function, we relate the time evolution of its mean-square…
Chemical synthesis of ceramic materials
A range of increasingly important chemical syntheses for ceramic materials are described. These syntheses are coprecipitation, molten salts, sol–gel processes, hydrothermal techniques, liquid-phase and gas-phase reactions, polymer pyrolysis, the Pechini and citrate gel methods, aerosols and emulsions. Common themes re…
Sandwich-type heteroleptic phthalocyaninato and porphyrinato metal complexes
Over the past decade, a substantial number of sandwich-type metal complexes with mixed phthalocyaninato and/or porphyrinato ligands have been synthesised. Owing to the intriguing π–π interactions associated with these complexes, this family of sandwich compounds displays unique physical, spectroscopic and electrochemi…
Room temperature growth of mesoporous silica fibers: A new high‐surface‐area optical waveguide
High‐quality, hexagonal phase, mesoporous silica fibers (see Figure) can be grown by the general procedure for one‐step, two‐phase, room temperature synthesis reported here. The silica fibers, which are 1–5 μm in diameter and up to 5 cm long, have excellent long‐range order, a narrow pore size distribution, and a pore…
Self-Assembly and Disassembly of Regioregular, Water Soluble Polythiophenes: Chemoselective Ionchromatic Sensing in Water
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationSelf-Assembly and Disassembly of Regioregular, Water Soluble Polythiophenes: Chemoselective Ionchromatic Sensing in WaterRichard D. McCullough, Paul C. Ewbank, and Robert S. LoeweView Author Information Department of Chemistry, Carnegie Mellon University Pittsburgh, Pennsy…
Conjugated polymers incorporating pendant functional groups—synthesis and characterisation
The subject of this review is the synthesis and electropolymerisation of pyrroles or thiophenes with pendant functional groups (metal complexes, ligands, biomolecules for protein binding etc.) to afford electrodes coated with a polymeric matrix containing the desired functionality. Such electrodes are being examined i…
Calculation of NMR shielding tensors based on density functional theory and a scalar relativistic Pauli-type Hamiltonian. The application to transition metal complexes
This article deals with the calculation of the shielding tensor of nuclear magnetic resonance (NMR) spectroscopy based on a scalar relativistic two-component Pauli-type Hamiltonian. A complete formulation of the method within the framework of the gauge including atomic orbitals (GIAO) is given. Further, an implementat…
Gelatin from cod skins as affected by chemical treatments
ABSTRACT Concentrations of sodium hydroxide, sulfuric and citric acids used in processing gelatin from cod skins affected both yield and quality. The highest yield of gelatin was obtained when low concentrations [0.1–0.2% (w/v)] of sulfuric acid and sodium hydroxide were applied to the skins followed by treatment with…
Purification and size‐selection of carbon nanotubes
A non‐destructive method for purifying carbon nanotubes produced by are discharge is described. The nanotubes, in the form of a kinetically stable colloidal dispersion in a water–surfactant solution, are separated from the nanoparticles by filtration. The Figure shows that purified nanotubes after two filtration steps…
Atomistic simulation of the surface structure of the TiO2 polymorphs rutileand anatase
Atomistic simulation has been used to calculate the surface structures and stability of the rutile and anatase polymorphs of TiO 2 . The surface and attachment energies were used to evaluate the equilibrium and pseudo-kinetic morphologies. The surfaces expressed in rutile were {011}, {110}, {100} and {221} with surfac…
Improvement of Hydrothermal Stability of MCM-41 Using Salt Effects during the Crystallization Process
Low hydrothermal stability in hot water and aqueous solutions was a critical problem for many applications of the mesoporous molecular sieve MCM-41, compared with conventional zeolites such as Y and ZSM-5. The hydrothermal stability of MCM-41 has been found to improve remarkably by using various salts such as sodium c…
Chemical Kinetics of Solids
Preface Symbols and Definitions Introduction Thermodynamics of Point Defects One- and Two-dimensional Defects in Crystals Basic Kinetic Concepts and Situations Kinetics and Dynamics. Local Equilibrium Heterogeneous Solid State Reactions Oxidation of Metals Solids in Thermodynamic Potential Gradients Internal Reactions…
CONVECTION IN MUSHY LAYERS
▪ Abstract As a molten alloy or any multi-component liquid is cooled and solidified the growing solid phase usually forms a porous matrix through which the residual liquid can flow. The reactive two-phase medium comprising the solid matrix and residual liquid is called a mushy layer. Buoyancy forces, owing primarily t…
A study of cell nucleation in the extrusion of polypropylene foams
Abstract An investigation has been performed of the cell nucleation and initial growth behaviors in the foam processing of polypropylene (PP) in both the linear and branched forms. These materials were foamed in extrusion with the two blowing agents, CO 2 and isopentane. The cell density generally increased with an in…