Instanton Contribution to the Pion Electro-Magnetic Formfactor at Q^2 > 1 GeV^2

We study the effects of instantons on the charged pion electro-magnetic formfactor at intermediate momenta. In the Single Instanton Approximation (SIA), we predict the pion formfactor in the kinematic region Q^2=2-15 GeV^2. By developing the calculation in a mixed time-momentum representation, it is possible to maximally reduce the model dependence and to calculate the formfactor directly. We find the intriguing result that the SIA calculation coincides with the vector dominance monopole form, up to surprisingly high momentum transfer Q^2~10 GeV^2. This suggests that vector dominance for the pion holds beyond low energy nuclear physics.Comment: 8 pages, 5 figures, minor revision

Calculations of fluid phase equilibria in systems of polyethylene and ethylene: An investigation into the applicability of the theory of Sanchez and Lacombe

The equation of state of Sanchez and Lacombe, based on a fluid lattice model, has been used for the prediction of the phase behaviour of systems of ethylene + polyethylene at near critical conditions. The model uses three pure component parameters for each pure component and one binary interaction parameter for each pair of components. Effects as chain branching and molecular weight distribution, typical for polymeric compounds, have been excluded from calculations by first testing the equation of state for two well defined systems of ethylene+ n-C20 and ethylene + n-C40. Phase equilibria in these systems have been calculated using pure component parameters from literature, as well as parameters optimized by fitting experimental PVT data to the equation of state. Although the prediction of pure component behaviour is really good with the parameters, the prediction of the binary phase equilibria is loose, concerning the location of the critical point. The phase equilibria can be predicted in a more reliable way by an empirical alteration of one of the pure component parameters, the characteristic pressure. Using this altered set of parameters, the location of the critical point can be predicted in agreement with experimental results, for above mentioned systems as well as for systems of ethylene + polyethylene. However, the reliability of these predictions are overshadowed by the very large influence of the binary interaction parameter on the calculated P-x curves, especially for systems of high molecular weight. The influence of components as propane and n-C12 on the phase equilibria of ethylene+ polyethylene has been investigated in a qualitative way. The calculations show that little amounts of propane or n-Cl2 suppress the occurrence of phase separation in the system ethylene+ polyethylene.Applied SciencesChemical Technology and Materials ScienceApplied Thermodynamics and Phase Equilibri

Equations of state for polymer solutions: Literature review

A literature search has been carried out to equations of state for polymer solutions. The equations of state have usually been based on the statistical mechanical approach of the partition function, which concept is discussed briefly. The main equation of state theories are presented in this script; cell models, fluid lattice models and combinations of them, for pure fluids and for mixtures. All theories mentioned do have the use of molecular para­meters in common which, in most cases, are to be obtained from experimental PVT data. In literature, little attention has been paid to the application of equations of state at supercritical condi­tions. A summary of the literature found on this subject is given.Applied SciencesScheikundige Technologie en der MateriaalkundeApplied Thermodynamics and Phase Equilibri

Een proces voor de produktie van koelmiddel 134a

Document uit de collectie Chemische ProcestechnologieDelftChemTechApplied Science

Quantitative analysis of antiretroviral drugs in lysates of peripheral blood mononuclear cells using MALDI-triple quadrupole mass spectrometry.

Contains fulltext : 71285.pdf (publisher's version ) (Open Access)We report here on the use of a prototype matrix-assisted laser desorption/ionization (MALDI)-triple quadrupole mass spectrometer for quantitative analysis of six antiretroviral drugs in lysates of peripheral blood mononuclear cells (PBMC). Of the five investigated MALDI matrixes, 2,5-dihydroxybenzoic acid (DHB) and the novel 7-hydroxy-4-(trifluoromethyl)coumarin (HFMC) showed the broadest application ranges for the antiretroviral drugs. For DHB, the mean relative errors ranged from 8.3 (ritonavir) to 4.3% (saquinavir). The mean precisions (CV) ranged from 17.3 (nevirapine) to 10.8% (saquinavir). The obtained lower limits of quantitation (LLOQ) readily allow clinical applications using just 1 million PBMC from HIV-infected patients under therapy. The new matrix HFMC was used for quantitative analysis of the HIV protease inhibitor indinavir using a stainless steel target plate as well as a target plate with a novel, strongly hydrophobic fluoropolymer coating. Using the coated target plate, the mean relative error improved from 10.1 to 4.6%, the mean precision from 33.9 to 9.9% CV, and the LLOQ from 16 to 1 fmol. In addition, the measurement time for one spot went down from 6 to only 2.5 s