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The Colloidal Domain – where physics, chemistry, biology and technology meet

The Society’s Site: Time period September 2001 to February 2002

Rheological properties of suspensions with spherical particles in shear and elongational flows

The rheological behaviour of model suspensions with spherical particles was experimentally investigated in shear an elongational flows. Particular attention was focussed on the main parameters affecting the flow behaviour of suspensions such as particle size distribution, particle size, particle surface, humidity, tem…

Isomorphism of hierarchical structures

We consider hierarchical structures such as Fibonacci sequences and Penrose tilings, and examine the consequences of different choices for the definition of isomorphism. In particular, we discuss the role such a choice plays with regard to matching rules for such structures.

High-power resonant measurements of piezoelectric materials: Importance of elastic nonlinearities

A resonance method for measuring the complex elastic and electromechanical properties of piezoelectric materials under high-power operational conditions has been developed. In this method, rectangular specimens are piezoelectrically driven into mechanical resonance. The displacement of the transverse resonance mode is…

Electrical Properties of Cerium‐Doped BaTiO 3

The high‐temperature equilibrium electrical conductivity of Ce‐doped BaTiO 3 was studied in terms of oxygen partial pressure, P (O 2 ), and composition. In (Ba 1−x Ce x )TiO 3 , the conductivity follows the −1/4 power dependence of P (O 2 ) at high oxygen activities, which supports the view that metal vacancies are cr…

Effect of Insulation Properties on the Field Grading of Solid Dielectric DC Cable

The development of solid dielectric dc transmission class cable is a priority throughout much of the world, to avoid risks associated with placing hydrocarbon fluids in underwater environments. The conductivity of polymeric solid dielectrics tends to be a strong function of temperature and electric field, however. Bas…

Safety of Magnetic Resonance Contrast Media

Intravenous contrast media, specifically the gadolinium chelates, are well accepted for use in the clinical practice of magnetic resonance imaging. The gadolinium chelates are considered to be very safe and lack (in intravenous use) the nephrotoxicity found with iodinated contrast media. Minor adverse reactions, inclu…

A uniform phenomenological constitutive model for glassy and semicrystalline polymers

Abstract A phenomenological constitutive model is proposed on the basis of four models: the Johnson‐Cook model, the G'Sell‐Jonas model, the Matsuoka model, and the Brooks model. The proposed constitutive model has a concise expression of stress dependence on strain, strain rate and temperature. It is capable of unifor…

Biodegradable Polymers from Renewable Sources. New Hemicellulose-Based Hydrogels

Hemicellulose/poly(2-hydroxyethyl methacrylate) (PHEMA)-based hydrogels were prepared by the radical polymerization of HEMA with hemicellulose purposely modified with well-defined amounts of methacrylic functions using a redox initiator system. Oligomeric hydrosoluble hemicelluloses produced from spruce chips were use…

Properties of Biodegradable Multilayer Films Based on Plasticized Wheat Starch

Multilayer films based on plasticized wheat starch (PWS) and various biodegradable aliphatic polyesters have been prepared through flat film coextrusion and compression molding. Poly(lactic acid) (PLA), polyesteramide (PEA), poly(μ-caprolactone) (PCL), poly(butylene succinate adipate) (PBSA), and poly(hydroxybutyrate-…

Relaxation time of weakly interacting superparamagnets

The relaxation time of weakly interacting classical spins is calculated by introducing the averages of the local dipolar field, obtained by thermodynamic perturbation theory, in a rigorous expression for the single-spin thermoactivation rate in a weak but arbitrarily oriented field. At low temperatures the non-trivial…

Polymer Based Nanocomposites: Effect of Filler-Filler and Filler-Matrix Interactions

Nanocomposite materials present specific features, mainly due to their very high interfacial area, and a very short distance between reinforcing particles surface. For polymer based nanocomposites, reinforcing particles are most of the time much stiffer than the matrix. In that case, the percolation of those particles…

Non-hydrogen Bond Interactions Involving the Methionine Sulfur Atom

Of all the nonbonded interactions, hydrogen bond, because of its geometry involving polar atoms, is the most easily recognizable. Here we characterize two interactions involving the divalent sulfur of methionine (Met) residues that do not need any participation of proton. In one an oxygen atom of the main-chain carbon…

Effect of compatibilizer on the structure‐property relationships of kenaf‐fiber/polypropylene composites

Abstract Although lignocellulosic, fiber‐thermoplastics composites have been used for several decades, recent economic and environmental advantages have resulted in significant commercial interest in the use of these fibers for several applications. Kenaf is a fast growing annual growth plant that is harvested for its…

Microscopy and computational modelling to elucidate the enhancement factor for field electron emitters

We report on the computation of the electric field at the surface of single‐tip field emitters for a variety of geometries and wide range of geometrical parameters. In conjunction with experimental work, this has allowed the determination of quantities useful for characterizing and comparing the performance of field e…

Global Status of the Production of Biobased Packaging Materials

Bioplastics from renewable origin are a new generation of plastics able to significantly reduce the environmental impact in terms of energy consumption and green-house ef-fect in specific applications. Bioplastics perform as traditional plastics when in use and are completely biodegradable within a composting cycle. T…

Tissue-Engineered Vascular Autograft: Inferior Vena Cava Replacement in a Dog Model

Tissue-engineered vascular autografts (TEVAs) were made by seeding 4-6 x 10(6) of mixed cells obtained from femoral veins of mongrel dogs onto tube-shaped biodegradable polymer scaffolds composed of a polyglycolid acid (PGA) nonwoven fabric sheet and a copolymer of L-lactide and caprolactone (n = 4). After 7 days, the…

Direct Synthesis of Alkoxide-Intercalated Derivatives of Hydrocalcite-like Layered Double Hydroxides: Precursors for the Formation of Colloidal Layered Double Hydroxide Suspensions and Transparent Thin Films

Layered double hydroxide alkoxides obtained by precipitation of MII and MIII salts with NaOH in alcoholic solution have unique properties. They exhibit very large BET surfaces, indicating a pillared structure, and their slow hydrolysis yields very smooth, almost transparent films of the corresponding hydroxides (see F…

Porphyrin-based Sensitizers in the Detection and Treatment of Cancer: Recent Progress

It has been known for some time that porphyrins and related compounds have the ability to selectively accumulate in tumor tissues, and to persist there for long periods of time. This property, along with the well-described photophysical and photosensitizing properties of porphyrin-type molecules, has led to their pote…