Transport anomalies in glasses

We discuss a recently developed random walk model for ionic transport in glass, which offers a simple explanation to the so far unexplained transport anomalies in glassy ionic conductors: The set of anomalies combined under the name mixed alkali effect and the drastic increase of the ionic conductivity with the concentration of mobile ions. The model is based on the experimental evidence that ions maintain their distinct local environments and leads to the formation of fluctuating structural pathways. The connectivity of these pathways determines the ion mobility in the glassy network.     

On the stability of a class of kinetic equations

Stability properties of kinetic model equations (including discrete versions of the master equation and Boltzmann's equation) are derived by means of Lyapunov's direct method. The construction of suitable Lyapunov functions leads to results about the structural stability of the dynamical systems and makes it possible to compose more complicated systems from the given ones, preserving automatically some form of stability.     

Inquiry-based learning in mathematics and science: a comparative baseline study of teachers’ beliefs and practices across 12 European countries

In the European educational context, reports by expert groups have identified the necessity of a renewed pedagogy in schools to overcome deficits in science and mathematics teaching and to raise the standards of scientific and mathematical literacy. Inquiry-based learning (IBL) is considered the method of choice. However, it remains open to what extent IBL is actually used in day-to-day teaching. In the study presented here we elaborate—from the perspective of teachers—the current status of IBL in day-to-day teaching. Further, we explore what problems teachers anticipate when implementing IBL. In order to gain insight into the wide spectrum of practices in mathematics and science teaching in relation to IBL, a baseline study using teacher questionnaires was carried out in the 12 participating countries. We present selected results from this study that for the first time provides an overview of teachers’ beliefs and their reports on the current use of IBL practices in a European context. The results facilitate a cross-cultural comparison on the potentials and challenges of implementing IBL from the perspective of practicing teachers. Furthermore, the study reveals considerable differences between the teaching of mathematics and science subjects. The findings of the baseline study can serve as a reference line against which the impact of interventions to improve the quality of teaching and learning can be evaluated.     

Binding of Glycans to the SARS CoV-2 Spike Protein,an Open Question: NMR Data on Binding Site Localization,Affinity, and Selectivity

We have used NMR experiments to explore the binding of selected glycans and glycomimetics to the SARS CoV-2 spike glycoprotein (S-protein) and to its receptor binding domain (RBD). STD NMR experiments confirm the binding of sialoglycans to the S-protein of the prototypic Wuhan strain virus and yield dissociation constants in the millimolar range. The absence of STD effects for sialoglycans in the presence of the Omicron/BA.1 S-protein reflects a loss of binding as a result of S-protein evolution. Likewise, no STD effects are observed for the deletion mutant Δ143–145 of the Wuhan S-protein, thus supporting localization of the binding site in the N-terminal domain (NTD). The glycomimetics Oseltamivir and Zanamivir bind weakly to the S-protein of both virus strains. Binding of blood group antigens to the Wuhan S-protein cannot be confirmed by STD NMR. Using ¹H,¹⁵N TROSY HSQC-based chemical shift perturbation (CSP) experiments, we excluded binding of any of the ligands studied to the RBD of the Wuhan S-protein. Our results put reported data on glycan binding into perspective and shed new light on the potential role of glycan-binding to the S-protein.     

The Influence of the Fluctuation Amplitude on the Probe Characteristic

The time-averaged probe current is calculated by using a sampling method for sinusoidal and sawtooth-like oscillations of the space potential. The effect of oscillations on the measured plasma parameters obtained with the aid of the single probe method, double probe method and the method of the second derivative of the probe characteristic is discussed, with the electron saturation current being taken into account. In the ion current the values r_p/λ_D, λ/r_p and M_i characterizing the working regime are varied. The calculated results are checked by corresponding measurements in a beam generated plasma.     

Investigation of the Beam Plasma Discharge in Electronegative Gases Using the Second Derivative of Langmuir Probe Characteristics

The distribution of the charge carriers is measured and the influence of the attachment processes on the electron energy distribution function is demonstrated for beam plasma discharges in SF₆, CF₄ and O₂ with the aid of the second derivative of Langmuir probe characteristics. The structuration of the plasma into regions of predominating negative ions and regions of predominating electrons is determined by the the established radial T_e-profile. The dimension of the quasi electronfree plasma changes significantly as well at transition from the turbulent heating mechanism into the electron impact plasma generation as by occuring low-frequency instabilities. With increasing n_?/n_e a deficit of low energetic electrons appears in the electron energy distribution parallel to the formation of the negative ion peak. The saturation currents at n_e/n_?=0 yield the mass ratios between negative and positive ions.