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31.
The corrosive behaviour of caesium has been attributed in part to the presence of a non-metallic impurity such as oxygen. A photon-activation method for determining oxygen and carbon in caesium is described. Scintillation coincidence-counting and pulseheight discrimination are used to count the gamma-ray activity resulting from annihilation of the positrons emitted. Variation of beam energy has been investigated in order to obtain optimum irradiation conditions. In the samples analysed and under the conditions used, less than 100 ppm of oxygen and carbon can be detected. Results are compared with those from other methods. 相似文献
32.
Ranaweera K. R. Ranaweera Dimitra L. Capone Susan E. P. Bastian Daniel Cozzolino David W. Jeffery 《Molecules (Basel, Switzerland)》2021,26(14)
In a global context where trading of wines involves considerable economic value, the requirement to guarantee wine authenticity can never be underestimated. With the ever-increasing advancements in analytical platforms, research into spectroscopic methods is thriving as they offer a powerful tool for rapid wine authentication. In particular, spectroscopic techniques have been identified as a user-friendly and economical alternative to traditional analyses involving more complex instrumentation that may not readily be deployable in an industry setting. Chemometrics plays an indispensable role in the interpretation and modelling of spectral data and is frequently used in conjunction with spectroscopy for sample classification. Considering the variety of available techniques under the banner of spectroscopy, this review aims to provide an update on the most popular spectroscopic approaches and chemometric data analysis procedures that are applicable to wine authentication. 相似文献
33.
The growth of CdTe on (0001) and (10 0) surfaces of CdS was studied using low energy electron diffraction and photoelectron spectroscopy. The results indicate oriented growth of the CdTe films with a faster nucleation of CdTe on CdS(0001), explaining the preferred (111) orientation of CdTe films on polycrystalline substrates. The faster nucleation on the (0001) surface is attributed to the formation of a stable CdS(0001):Te surface termination, which is identified from surface sensitive Te 4d spectra and a 2√3 × 2√3 surface reconstruction. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
34.
Bastian Rsch Thomas Xaver Gentner Holger Elsen Christian A. Fischer Jens Langer Michael Wiesinger Sjoerd Harder 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(16):5450-5455
Key to the isolation of the first alkyl strontium complex was the synthesis of a strontium hydride complex that is stable towards ligand exchange reactions. This goal was achieved by using the super bulky β‐diketiminate ligand DIPePBDI (CH[C(Me)N‐DIPeP]2, DIPeP=2,6‐diisopentylphenyl). Reaction of DIPePBDI‐H with Sr[N(SiMe3)2]2 gave (DIPePBDI)SrN(SiMe3)2, which was converted with PhSiH3 into [(DIPePBDI)SrH]2. Dissolved in C6D6, the strontium hydride complex is stable up to 70 °C. At 60 °C, H–D isotope exchange gave full conversion into [(DIPePBDI)SrD]2 and C6D5H. Since H–D exchange with D2 is facile, the strontium hydride complex served as a catalyst for the deuteration of C6H6 by D2. Reaction of [(DIPePBDI)SrH]2 with ethylene gave [(DIPePBDI)SrEt]2. The high reactivity of this alkyl strontium complex is demonstrated by facile ethylene polymerization and nucleophilic aromatic substitution with C6D6, giving alkylated aromatic products and [(DIPePBDI)SrD]2. 相似文献
35.
We propose a novel method to directly extract the phase from spectral interferograms, without the need for digital signal processing. This method is demonstrated with single-shot measurement and stabilization of the carrier-envelope phase of a 3 kHz amplifier system. Our scheme allows for real-time monitoring of the carrier-envelope drift and an increased loop width for stabilization. We find that in our amplifier laser system fast carrier-envelope phase jitter is mainly inherited from the oscillator stabilization loop but we also find previously unreported indications for a rapid pulse-to-pulse jitter from the amplifier pump laser. 相似文献
36.
Hendrik Schneider Lukas Deweid Thomas Pirzer Desislava Yanakieva Simon Englert Bastian Becker Dr. Olga Avrutina Prof. Dr. Harald Kolmar 《ChemistryOpen》2019,8(3):354-357
Antibody-drug conjugates (ADCs) are multicomponent biomolecules that have emerged as a powerful tool for targeted tumor therapy. Combining specific binding of an immunoglobulin with toxic properties of a payload, they however often suffer from poor hydrophilicity when loaded with a high amount of toxins. To address these issues simultaneously, we developed dextramabs, a novel class of hybrid antibody-drug conjugates. In these architectures, the therapeutic antibody trastuzumab is equipped with a multivalent dextran polysaccharide that enables efficient loading with a potent toxin in a controllable fashion. Our modular chemoenzymatic approach provides an access to synthetic dextramabs bearing monomethyl auristatin as releasable cytotoxic cargo. They possess high drug-to-antibody ratios, remarkable hydrophilicity, and high toxicity in vitro. 相似文献
37.
Comparison of monomethoxy‐, dimethoxy‐, and trimethoxysilane anchor groups for surface‐initiated RAFT polymerization from silica surfaces
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Dennis Huebner Vanessa Koch Bastian Ebeling Jannik Mechau Judith Elisabeth Steinhoff Philipp Vana 《Journal of polymer science. Part A, Polymer chemistry》2015,53(1):103-113
The immobilization of reversible addition–fragmentation chain transfer (RAFT) agents on silica for surface‐initiated RAFT polymerizations (SI‐RAFT) via the Z‐group approach was studied systematically in dependence of the functionality of the RAFT‐agent anchor group. Monoalkoxy‐, dialkoxy‐, and trialkoxy silyl ether groups were incorporated into trithiocarbonate‐type RAFT agents and bound to planar silica surfaces as well as to silica nanoparticles. The immobilization efficiency and the structure of the bound RAFT‐agent film varied strongly in dependence of the used solvent (toluene vs. 1,2‐dimethoxyethane) and the anchor group functionality, as evidenced by atomic force microscopy, transmission electron microscopy, dynamic light scattering, and UV/Vis spectroscopy. Surface‐initiated RAFT polymerizations using functionalized silica nanoparticles revealed that grafted oligomers, which often occur in SI‐RAFT, are not formed within the crosslinked structures that originate from the immobilization, and that RAFT‐agent films that show less aggregation during the immobilization are more efficient during SI‐RAFT in terms of polymer grafting density. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 103–113 相似文献
38.
Maschler Tobias Strmer-Stephan Bastian Morhard Jrg Stegmaier Thomas Tilebein Meike Griepentrog Hans W. 《Annals of Operations Research》2022,314(2):577-600
Annals of Operations Research - Selecting a vegetation layer design goes along with determining its future irrigation need. Therefore, it is essential to take a design decision that is minimising... 相似文献
39.
Dr. Soichiro Ogi Natsumi Fukaya Dr. Arifin Bastian Bjerkem Skjelstad Dr. Yuh Hijikata Prof. Dr. Shigehiro Yamaguchi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(30):7303-7307
The self-assembly of an amide-functionalized dithienyldiketopyrrolopyrrole (DPP) dye in aqueous media was achieved through seed-initiated supramolecular polymerization. Temperature- and time-dependent studies showed that the spontaneous polymerization of the DPP derivative was temporally delayed upon cooling the monomer solution in a methanol/water mixture. Theoretical calculations revealed that an amide-functionalized DPP derivative adopts an energetically favorable folded conformation in the presence of water molecules due to hydration. This conformational change is most likely responsible for the trapping of monomers in the initial stage of the cooperative supramolecular polymerization in aqueous media. However, the monomeric species can selectively interact with externally added fragmented aggregates as seeds through concerted π-stacking and hydrogen-bonding interactions. Consequently, the time course of the supramolecular polymerization and the morphology of the aggregated state can be controlled, and one-dimensional fibers that exhibit a J-aggregate-like bathochromically shifted absorption band can be obtained. 相似文献
40.
Nonlinear Dynamics - An initially unstable equilibrium position of a system can be stabilized by introducing a parametric excitation. This is especially of interest for suppressing self-excited... 相似文献