Materials Literature
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The behavior of PAMAM-dendrimer encapsulated palladium nanoparticles as catalysts for the Heck reaction has been examined, and it has been demonstrated that this simple system is a very efficient catalyst giving good yields under phosphine-free conditions and with 200−400 times less Pd than usual.
Two desorption peaks of hydrogen molecule (mass number=2), starting at about 600 and 950 K, respectively, are observed in thermal desorption mass spectroscopy of nanostructured graphite mechanically milled for 80 h under hydrogen atmosphere. It follows from a combined analysis of thermal desorption mass spectroscopy a…
Rheology plays an important role in dewatering processes. It is therefore interesting to analyze the dewatering process and the rheological behavior of a suspension simultaneously. An exact determination of the immobilization point at the maximum of the loss factor as well as the immobilization time can be attained us…
The use of a conical twin screw extruder with backflow channel combines aspects of mixing and extrusion in a batch process. Tests and results of the new MINLAB mircocompounder are discussed in the following paper. With a total filling volume of 7 ml and a built in slit capillary die the applications focus on compoundi…
Abstract The rheological properties of thermotropic liquid crystalline polymer (LCP) and its carbon fiber (CF) and carbon black (CB) filled composites in molten state were measured using a cone-plate rheometer. The measurements of the CF/LCP and CB/LCP melts were performed with carbon fiber contents of 5, 10 and 20 wt…
With stress controlled rheometer we investigate the behavior for different concentrations, of paraffin oil-in-water emulsions, bentonite suspensions as well as charged bentonite emulsions. We were particularly interested in how aging affects the rheological properties. Using a structural model, we correlate the macros…
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…
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.
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…
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…
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…
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…
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…