Search results for " solution"

1993

In a new theoretical approach the separation of a pair of chain molecules (measured thermodynamically by the second osmotic virial coefficient A2) is treated as a two-step process: In the first step the molecules are detached from each other by the addition of solvent—keeping their dimensions constant—and in the second step the now isolated coils are allowed to relax into their equilibrium dimensions. For the description of the second step, in which only segments belonging to one molecule take part, an intra-molecular interaction parameter is introduced on the basis of the intrinsic viscosity. The present two-parameter approach yields A2 = A + σ M−(1−a) for the dependence of A2 on the molec…

A Viscosity Equation for Minimizers of a Class of Very Degenerate Elliptic Functionals

2013

We consider the functional $$J(v) = \int_\varOmega\bigl[f\bigl(|\nabla v|\bigr) - v\bigr] dx, $$ where Ω is a bounded domain and f:[0,+∞)→ℝ is a convex function vanishing for s∈[0,σ], with σ>0. We prove that a minimizer u of J satisfies an equation of the form $$\min\bigl(F\bigl(\nabla u, D^2 u\bigr), |\nabla u|-\sigma\bigr)=0 $$ in the viscosity sense.

Microgels of polyaspartamide and poly(ethylene glycol) derivatives obtained by γ-irradiation

2002

Abstract The copolymer PHG based on α , β -poly( N -2-hydroxyethyl)- dl -aspartamide (PHEA) functionalized with glycidyl methacrylate has been exposed in aqueous solution to a γ -ray source at different irradiation doses (2, 2.5 and 3.5 kGy), alone or in combination with poly(ethylene glycol)dimethacrylate (PEGDMA) or poly(ethylene glycol)diacrylate (PEGDA). The irradiation produces microgel systems that have been characterized by viscosity measurements. Lyophilization of microgels gives rise to samples able to swell instantaneously in water whereas their treatment with acetone produces swellable microparticles that have been characterized.

Effect of TiO2 on the mullite formation and mechanical properties of alumina porcelain

2010

Abstract The effect of adding TiO 2 to standard alumina porcelain on its microstructure and flexural strength was investigated. A series of alumina porcelain bodies containing increasing amounts of TiO 2 were prepared by extruding mixtures of raw materials and TiO 2 . Porcelain rods were fired under industrial scheduling in a manufacturing kiln. The overall degree of crystalline and amorphous phase content within the porcelain bodies was quantitatively determined using a Rietveld analysis. Results indicated a higher amount of mullite formation in porcelain bodies containing TiO 2 . Examination of the product materials using field emission scanning electron microscopy showed a high density o…

Die viskosität von polymerlösungen in der nähe von oberen und unteren entmischungstemperaturen

1977

Die Viskositat flussiger Mischungen zeigt in der Nahe des kritischen Entmischungspunktes eine charakteristische Temperaturabhangigkeit. fur Polymerlosungen ist diese Erscheinung bei der oberen kritischen Entmischungstemperatur gut untersucht, wahrend in der Umgebung der unteren kritischen Entmischungstemperatur keine derartigen Messungen vorliegen. ES wurden Viskositatsmessungen im System Cyclohexan/Polystyrol (obere kritische Entmischungstemperatur) und im System Orthotrimethylformiat/Diathylather/Polystyrol (untere kritische Entmischungstemperatur) durchgefuhrt. Beim ersten System ergab sich qualitative Ubereinstimmung mit den Ergebnissen von Debye und Mitarbeitern. Die Untersuchungen in …

Picosecond absorption spectroscopy: Methods and applications in photophysical and photochemical systems

1985

FIA-fluorimetric determination of thiamine.

1990

A flow injection-fluorimetric determination of thiamine is reported. The procedure is based on the oxidation of the analyte with potassium hexacyanoferrate(III) immobilized on an anionic exchange resin; the fluorescence is monitored in aqueous basic solution. Concentrations of the vitamin of 0.1-4 ppm have been determined; the relative standard deviation was 1.8%. The injection rate was 28 samples/h. The influence of other substances and the determination of the drug in a pharmaceutical formulation are also reported.

The warping torsion as a sequence of infinite bending problems

2014

[EN] In the present article, a methodology for teaching modeling problem of mixed torsion for thin-walled open sections. The mathematical analogy of warped twist as a problem of Euler-Bernoulli beams is exploited. In fact, the paper proposes to represent the warped torsion differential equation as a perturbation of the pure torsion or also called the Saint-Venant theory. Thus, it is demonstrated that under certain conditions related to the value of the torsional slenderness the response of a beam is the addition of infinite pure warped problems, that is, infinite bending problems, according to the analogy. We call this the asymptotic torsion analogy.

Dismantling and copper recovery from Waste Printed Circuit Boards (WPCBs) using an integrated hydro-electrometallurgical approach

Water Resource Recovery Facilities (WRRFs): The Case Study of Palermo University (Italy)

2021

The wastewater sector paradigm is shifting from wastewater treatment to resource recovery. In addition, concerns regarding sustainability during the operation have increased. In this sense, there is a need to break barriers (i.e., social, economic, technological, legal, etc.) for moving forward towards water resource recovery facilities and demonstration case studies can be very effective and insightful. This paper presents a new water resource recovery case study which is part of the Horizon 2020 EU Project “Achieving wider uptake of water-smart solutions—Wider Uptake”. The final aim is to demonstrate the importance of a resource recovery system based on the circular economy concept. The r…