Multianalytical Study of Patina Formed on Archaeological Metal Objects from Bliesbruck-Reinheim

 Patinas naturally formed on archaeological bronze alloys were characterized using light microscopy (LM), micro energy dispersive X-ray fluorescence analysis (μ-EDXRF), time of flight secondary ion mass spectrometry (TOF-SIMS) and scanning electron microscopy in combination with energy dispersive X-ray microanalysis (SEM/EDX). The examinations carried out on cross-sections of samples have shown that in all samples the copper content in the corrosion layer is lower than in the bulk, while an increase of tin and lead could be observed. Two different types of corrosion were found: first type, a corrosion formation leading to a three layer structure was observed on lead bronze. The outer layer consists mainly of Cu(II) compounds and soil material, followed by a fragmented layer of cuprous oxide and the surface layer of the alloy, where a depletion of copper and an enrichment of tin and high amounts of Cl could be detected. The second type of corrosion is characterized by a two layer structure on the tin bronze sample consisting of an outer layer with copper containing corrosion products and a layer with cracks, which reveals a depletion of copper whereas tin and lead are enriched. Also high amounts of Si were detected in this surface layer.     

Enzyme mediated incorporation of zirconium-89 or copper-64 into a fragment antibody for same day imaging of epidermal growth factor receptor

Identification of tumors which over-express Epidermal Growth Factor Receptor (EGFR) is important in selecting patients for anti-EGFR therapies. Enzymatic bioconjugation was used to introduce positron-emitting radionuclides (⁸⁹Zr, ⁶⁴Cu) into an anti-EGFR antibody fragment for Positron Emission Tomography (PET) imaging the same day as injection. A monovalent antibody fragment with high affinity for EGFR was engineered to include a sequence that is recognized by the transpeptidase sortase A. Two different metal chelators, one for ⁸⁹Zr^IV and one for ⁶⁴Cu^II, were modified with a N-terminal glycine to enable them to act as substrates in sortase A mediated bioconjugation to the antibody fragment. Both fragments provided high-quality PET images of EGFR positive tumors in a mouse model at 3 hours post-injection, a significant advantage when compared to radiolabeled full antibodies that require several days between injection of the tracer and imaging. The use of enzymatic bioconjugation gives reproducible homogeneous products with the metal complexes selectively installed on the C-terminus of the antibody potentially simplifying regulatory approval.

Enzymatic bioconjugation to introduce positron-emitting radionuclides (⁸⁹Zr, ⁶⁴Cu) into an anti-EGFR antibody fragment allows same day imaging with positron emission tomography.     

2-Ranks of incidence matrices associated with conics in finite projective planes

In this article, we investigate geometric properties of the secant-internal neighbors of internal points and the passant-external neighbors of external points in classical finite projective planes; we calculate the \(2\) -ranks of the incidence matrices of internal points versus their secant-internal neighbors and external points versus their passant-external neighbors using a combination of techniques from both finite geometry and linear algebra.     

Canard cycle transition at a slow–fast passage through a jump point

We introduce transitory canard cycles for slow–fast vector fields in the plane. Such cycles separate “canards without head” and “canards with head”, like for example in the Van der Pol equation. We obtain optimal upper bounds on the number of periodic orbits that can appear near the cycle under whatever condition on the related slow divergence integral I  , including the challenging case I=0$I=0$.     

Classroom Response Systems: Effects on the Critical Analysis Skills of Students in Introductory Science Courses

College instructors often teach scientific thinking by asking students to review and analyze a primary research article. The main purpose of this study was to explore how classroom response systems (CRS) could help impact the quality of written analysis papers submitted for this assignment by students taking 100‐level biology courses at a medium‐sized suburban, two‐year college in the northeastern United States. Students in all participating course sections received written instructions on five key elements of critical analysis (CA) to include in scientific study analysis papers. Classroom instruction on recognizing these key elements in primary research papers was provided either via CRS or via an instructor‐facilitated classroom discussion enhanced by the same PowerPoint presentation. A rubric, designed specifically for this assignment, was validated prior to its use in this study. Fifty students participated in the study, and those who received the CRS intervention achieved significantly higher CA scores for identifying implications of study findings, while the group that received only written instructions achieved significantly higher CA scores for discussing the credibility of the references used by the authors in planning the critiqued study. The implications of this study are discussed along with ideas for future research.     

Thermodynamic and dielectric properties of polar lattices

Monte Carlo results are presented for the free energy and dielectric constant of systems of permanent dipoles disposed on the sites of simple cubic and face-centred cubic lattices as functions of the parameter ? = μ²ρ/kT. Alternative schemes are considered for taking account of the long-range character of the dipolar interaction, based on an Ewald-type sum or a reaction-field approximation; use of such a procedure is essential if the system is to have the correct dielectric properties. Different methods of calculating the dielectric constant are also compared. It is shown that the two methods of treating the long-range contribution to the energy lead to similar results for the dielectric constant, but use of the Ewald method apparently introduces a small but systematic error. The results on both free energy and dielectric constant are discussed in the light of predictions of a number of analytical approaches. In the case of the simple cubic lattice the general trend in the computed dielectric constant as a function of ? is in closer accord with the solution of the mean spherical approximation than with a simple Padé approximant to the Clausius-Mossotti function.     

Light hole transport in a strained GaAs/In0.18Ga0.82As quantum well at high pressures

Abstract

Here we report what we believe to be the first observation of the pressure dependence of the light hole behavior in a modulation doped In_0.18Ga_0.82As/GaAs single strained quantum well grown by MBE. Transport measurements have been undertaken as a function of temperature (4–300K) and hydrostatic pressure (4–8kbar). Hole mobilities of ～17000 cm²/Vs have been obtained for sheet carrier densities of ～3.3×10¹¹ cm^?2. At low temperatures (<100K) persistent photogenerated holes have been observed. The hole mobility is found to decrease with increasing pressure at a rate intermediate between that typically observed for holes and electrons in bulk III-V semiconductors.     

Study of semiconductor lasers under simultaneous uniaxial stress and hydrostatic pressure

Abstract

We present the design of a device for the simultaneous application of uniaxial stress and hydrostatic pressure. This new apparatus will for the first time allow measurements at constant strain. Results of the simultaneous application of uniaxial stress and hydrostatic pressure to a semiconductor laser are presented and discussed.     

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Ohne Zusammenfassung     

Large Deviation Techniques Applied to Systems with Long-Range Interactions

We discuss a method to solve models with long-range interactions in the microcanonical and canonical ensemble. The method closely follows the one introduced by R.S. Ellis, Physica D 133:106 (1999), which uses large deviation techniques. We show how it can be adapted to obtain the solution of a large class of simple models, which can show ensemble inequivalence. The model Hamiltonian can have both discrete (Ising, Potts) and continuous (HMF, Free Electron Laser) state variables. This latter extension gives access to the comparison with dynamics and to the study of non-equilibrium effects. We treat both infinite range and slowly decreasing interactions and, in particular, we present the solution of the α-Ising model in one-dimension with 0 ⩽ α < 1.