Chemical durability of sodium disilicate glasses in different corrosion media at neutral to basic pH values

The chemical corrosion of sodium disilicate glasses in neutral to basic media was investigated. H2O, 1 mol/l NaOH, 1 mol/l LiOH, and a dilution series of sodium silicate solutions with a molar SiO2:Na2O ratio of 2.18 were used as corrosion media in static corrosion tests at temperatures of 30 °C and corrosion times up to 180 d. The corrosion process was characterized gravimetrically and in some cases by chemical analysis. Additionally, the temperature dependence of the corrosion in H2O at temperatures up to 70 °C was investigated. The nature of the corrosion process depends on the character of the corrosion media: The corrosion in 1 mol/l NaOH and 1 mol/l LiOH follows predominantly a square root time law, whereas corrosion in H2O or in sodium silicate solutions can be described by a linear time law. An additional result is that the corrosion rates increase in all cases with pH: in the case descnbed here corrosion in H2O and in alkaline silicate solutions proceeds faster than corrosion in sodium or lithium hydroxide solutions with higher pH values. The dilution series of sodium silicate solutions was used to check the dependence of the corrosion process on the concentration of glass dissolution products in the leachate. The results indicate the importance of surface adsorption processes

Detection of Adenoviruses from clinical samples in bone marrow transplant patients by nested PCR (polymerase chain reaction)

Adenoviruses are recognized as common human pathogens that are responsible for a wide variety of infectious syndromes. Bone marrow transplant patients are prone to life threatening opportunistic infections like adenoviruses. The nested polymerase chain reaction has provided an alternative, sensitive diagnostic method for detection of Adenoviruses. In this study we developed PCR from hexon genes as rapid diagnostic method of Advs infections on different clinical samples. Adenovirus infections was defined as the presence of DNA in the blood, urine, stool, or respiratory lavage from bone marrow transplant patients. Two sets of primers (Group specific primers and internal primers) were required to optimize the PCR protocol. This highly sensitive method could detect different types of Advs in two separate sets of PCR. Therfore,DNA amplification in BMT patients would be valuable screening way to evaluate bone marrow transplant recipients. Early detection of Advs by PCR assay is important to asymptomatic infections or preventing aggressive antiviral thearapy

Zur Virusätiologie der idiopathischen Fazialisparese (Enzymimmunserologische Untersuchungen) = On the viral etiology of Bell's palsy (An enzyme-linked immunosorbent assay study) [author's transl.]

In a prospective study paired sera of 14 patients suffering from Bell's palsy were examined for antibodies against Varicella-zoster Virus (VZV), Herpes-simplex Virus (HSV), Cytomegalovirus (CMV) and Epstein-Barr Virus (EBV). For determination of antibodies against VZV, HSV and CMV an enzyme-linked immunosorbent assay was carried out. Indirect immunofluorescence was carried out to determine antibodies against EBV. Serum samples were taken within 5 days of Bell's palsy having been diagnosed and were compared with further serum samples taken 4 weeks later. No evidence of significant differences between the antibody titers of the paired sera was found. The viral etiology of Bell's palsy due to an exogenous infection or by activation of a latent infection seems unlikely

Potentielle Auswirkungen von Bodenfonds als Kapitalanlage auf landwirtschaftliche Betriebe

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Gibbs Phenomena for LqL^q-Best Approximation in Finite Element Spaces -- Some Examples

Recent developments in the context of minimum residual finite element methods are paving the way for designing finite element methods in non-standard function spaces. This, in particular, permits the selection of a solution space in which the best approximation of the solution has desirable properties. One of the biggest challenges in designing finite element methods are non-physical oscillations near thin layers and jump discontinuities. In this article we investigate Gibbs phenomena in the context of $L^q$-best approximation of discontinuities in finite element spaces with $1\leq q<\infty$. Using carefully selected examples, we show that on certain meshes the Gibbs phenomenon can be eliminated in the limit as $q$ tends to $1$. The aim here is to show the potential of $L^1$ as a solution space in connection with suitably designed meshes

Eliminating Gibbs Phenomena: A Non-linear Petrov-Galerkin Method for the Convection-Diffusion-Reaction Equation

In this article we consider the numerical approximation of the convection-diffusion-reaction equation. One of the main challenges of designing a numerical method for this problem is that boundary layers occurring in the convection-dominated case can lead to non-physical oscillations in the numerical approximation, often referred to as Gibbs phenomena. The idea of this article is to consider the approximation problem as a residual minimization in dual norms in Lq-type Sobolev spaces, with 1 < q < $\infty$. We then apply a non-standard, non-linear PetrovGalerkin discretization, that is applicable to reflexive Banach spaces such that the space itself and its dual are strictly convex. Similar to discontinuous Petrov-Galerkin methods, this method is based on minimizing the residual in a dual norm. Replacing the intractable dual norm by a suitable discrete dual norm gives rise to a non-linear inexact mixed method. This generalizes the Petrov-Galerkin framework developed in the context of discontinuous Petrov-Galerkin methods to more general Banach spaces. For the convection-diffusion-reaction equation, this yields a generalization of a similar approach from the L2-setting to the Lq-setting. A key advantage of considering a more general Banach space setting is that, in certain cases, the oscillations in the numerical approximation vanish as q tends to 1, as we will demonstrate using a few simple numerical examples