Ion beam mixing of silicon-tin multilayers

Silicon and tin multilayers of total thickness 200 nm have been deposited at room temperature on beryllium and glass plate substrates under high vacuum (<5. 10^?7 mbar). The average atomic tin fraction of the whole layer varied from 0.12 to 0.60. The samples were irradiated at room temperature with Xe⁺ ions of 900 keV energy with fluences of 1.10¹⁵ to 2.10¹⁶ ions. cm^?2. Rutherford backscattering spectrometry (RBS) was used to check overall composition before irradiation. After irradiation, a substitutional Sn site was evidenced by means of¹¹⁹Sn conversion electron Mössbauer spectroscopy (CEMS), the relative population of which depends on composition and irradiation fluence. Transmission electron microscopy (TEM) was used to monitor the evolution of the samples with irradiation fluence. Electrical measurements show semiconductor behaviour of the mixed multilayers with electrical resistivity ranging from 10² to 10^?3 Ω.cm as a function of composition.     

Global gradient bounds for relaxed variational problems

We prove global Lipschitz regularity for solutionsu : Ω → ℝ ^N of some relaxed variational problems in classes of functions with prescribed Dirichlet boundary data. The variational integrals under consideration are of the form ∫_Ω W(▽ _u )dx withW of quadratic growth.     

Metallorganische Lewis-Säuren : LII. Kationische Pentacarbonylcarben-Komplexe von Mangan und Rhenium, [(OC)5 H2]BF4 (M = Mn, Re)

The pentacarbonyltetrafluoroborato complexes (OC)₅MFBF₃ react with 3-butyne-1-ol to give the cyclic oxycarbene complexes [(OC)₅M--- H₂]⁺BF₄⁻ (1: M = Mn; 2: M = Re). The structure of 2 has been determined by X-ray diffraction.     

Micro-perforated structures as stand-alone sound absorbers

1 Introduction Early attempts to create a sound absorber which would function without the involvement of any fibrous or porous damping material go far back to K. A. Veliszhanina, S. N. Rschevkin and others as was outlined in Ref. [1]. 30 years ago, D. Y. MAA[2] was first in proposing a practicable design concept and calculation model for Micro-Perforated Absorber (MPA) prototypes which still forms the basis for various applications. During the past 12 years the Fraunhofer IBP     

Formation of a non-crystalline bimolecular porous network at a liquid/solid interface

An equimolar mixture of two structurally related molecular building blocks self-assembles into a 2D non-crystalline bimolecular porous pattern at a liquid-solid interface as revealed by scanning tunneling microscopy.     

Minor groove binders and drugs targeting proteins cover complementary regions in chemical shape space

DNA minor groove binders (MGBs) are known to influence gene expression and are therefore widely studied to explore their therapeutic potential. We identified shape-based virtual screening with ROCS as a highly effective computational approach to enrich known MGBs in top-ranked molecules. Discovery of ten previously unknown MGBs by shape-based screening further confirmed the relevance of ligand shape for minor groove affinity. Based on experimental testing we propose three simple rules (at least two positive charges, four nitrogen atoms, and one aromatic ring) as filters to reach even better enrichment of true positives in ROCS hit lists. Interestingly, shape-based ranking of MGBs versus FDA-approved drugs again leads to high enrichment rates, indicating complementary coverage of chemical shape space and indicating minor groove affinity to be unfavorable for approval of drugs targeting proteins.     

Strong approximation in the Apollonian group

The Apollonian group is a finitely generated, infinite index subgroup of the orthogonal group OQ(Z) fixing the Descartes quadratic form Q. For nonzero v∈Z⁴ satisfying Q(v)=0, the orbits Pv=Av correspond to Apollonian circle packings in which every circle has integer curvature. In this paper, we specify the reduction of primitive orbits Pv mod any integer d>1. We show that this reduction has a multiplicative structure, and that mod primes p?5 it is the full cone of integer solutions to Q(v)≡0 for v?0. This analysis is an essential ingredient in applications of the affine linear sieve as developed by Bourgain, Gamburd and Sarnak.     

Increased strontium uptake in trabecular bone of ovariectomized calcium‐deficient rats treated with strontium ranelate or strontium chloride

Based on clinical trials showing the efficacy to reduce vertebral and non‐vertebral fractures, strontium ranelate (SrR) has been approved in several countries for the treatment of postmenopausal osteoporosis. Hence, it is of special clinical interest to elucidate how the Sr uptake is influenced by dietary Ca deficiency as well as by the formula of Sr administration, SrR versus strontium chloride (SrCl₂). Three‐month‐old ovariectomized rats were treated for 90 days with doses of 25 mg kg^?1 d^?1 and 150 mg kg^?1 d^?1 of SrR or SrCl₂ at low (0.1% Ca) or normal (1.19% Ca) Ca diet. Vertebral bone tissue was analysed by confocal synchrotron‐radiation‐induced micro X‐ray fluorescence and by backscattered electron imaging. Principal component analysis and k‐means clustering of the acquired elemental maps of Ca and Sr revealed that the newly formed bone exhibited the highest Sr fractions and that low Ca diet increased the Sr uptake by a factor of three to four. Furthermore, Sr uptake in bone of the SrCl₂‐treated animals was generally lower compared with SrR. The study clearly shows that inadequate nutritional calcium intake significantly increases uptake of Sr in serum as well as in trabecular bone matrix. This indicates that nutritional calcium intake as well as serum Ca levels are important regulators of any Sr treatment.     

Lipschitz regularity for constrained local minimizers of convex variational integrals with a wide range of anisotropy

We establish interior gradient bounds for functions ${u \in W^1_{1, {\rm loc}} (\Omega)}$ which locally minimize the variational integral ${J [u, \Omega] = \int_\Omega h \left( |\nabla u| \right) dx}$ under the side condition ${u \ge \Psi}$ a.e. on Ω with obstacle ${\Psi}$ being locally Lipschitz. Here h denotes a rather general N-function allowing (p, q)-ellipticity with arbitrary exponents 1 < p ≤ q < ∞. Our arguments are based on ideas developed in Bildhauer et al. (Z Anal Anw 20:959–985, 2001) combined with techniques originating in Fuchs (2011).