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991.
992.
Michael Radius Dr. Ewald Sattler Helga Berberich Prof. Dr. Frank Breher 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(52):12206-12213
The influence of substituents on α-borylated phosphorus ylides (α-BCPs) has been investigated in a combined experimental and quantum chemical approach. The synthesis and characterization of Me3PC(H)B(iBu)2 ( 1 ), consisting of small Me substituents on phosphorous and iBu residues on boron, is reported. Compound 1 is accessible through a novel synthetic approach, which has been further elucidated through DFT studies. The reactivity of 1 towards various small molecules was probed and compared with that of a previously published derivative, Ph3PC(Me)BEt2 ( 2 ). Both α-BCPs react with NH3 to undergo heterolytic N−H bond cleavage. Different di- and trimeric ring structures were observed in the reaction products of 1 with CO and CO2. With PhNCO and PHNCS, the expected insertion products [Me3PC(H)(PhNCO)B(iBu)2] and [Me3PC(H)(PhNCS)B(iBu)2], respectively, were isolated. 相似文献
993.
Björn-Hendrik Peters James Bautista Thomas R. Slaney Hongyue Guo Richard Y.-C. Huang Mary E. Krause Ming Zeng Julie Cheng Zhi Chen 《Electrophoresis》2022,43(9-10):1059-1067
Antibody-based therapeutic proteins have highly complex molecular structures. The final therapeutic protein product may contain a wide range of charge variants. Accurate analysis of this charge variant composition is critical to determine manufacturing process consistency and protein stability and ultimately helps to ensure that patients receive a safe and efficacious product. Here, a highly sialylated bispecific antibody (bsAb-1) challenged the ability to monitor stability by imaged capillary isoelectric focusing (iCIEF). This challenge was overcome by optimization of the iCIEF master mix buffer (adjustment of urea concentration, addition of l -arginine) and enzymatic removal of sialic acid. The method was qualified by assessing linearity, precision, LOD, LOQ, accuracy, and robustness in accordance with ICH guidance. Main species loss detectability increased up to approximately fivefold compared to the iCIEF method without desialylation when monitoring changes in stressed samples. Importantly, the results of the iCIEF method with desialylation correlated with results obtained through LC–MS tryptic peptide mapping and enabled analysis of formulation development stability samples. Finally, this analytical method shows the potential to assess low-concentration formulation development samples down to a sample concentration of 0.1 mg/ml. 相似文献
994.
995.
Cladek Laura Henriot Kevin Krause Ben Łaba Izabella Pramanik Malabika 《Mathematische Zeitschrift》2018,289(3-4):1033-1057
Mathematische Zeitschrift - Consider the discrete maximal function acting on finitely supported functions on the integers, $$\begin{aligned} \mathcal {C}_\Lambda f(n) := \sup _{\lambda \in \Lambda... 相似文献
996.
Back Cover: A Synthetic Toolbox for the In Situ Formation of Functionalized Homo‐ and Heteropolysaccharide‐Based Hydrogel Libraries (Chem. Eur. J. 52/2016)
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997.
Alicia Casitas Helga Krause Richard Goddard Alois Fürstner 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(5):1541-1546
The alkylation of complexes 2 and 7 with Grignard reagents containing β‐hydrogen atoms is a process of considerable relevance for the understanding of C–H activation as well as C–C bond formation mediated by low‐valent iron species. Specifically, reaction of 2 with EtMgBr under an ethylene atmosphere affords the bis‐ethylene complex 1 which is an active precatalyst for prototype [2+2+2] cycloaddition reactions and a valuable probe for mechanistic studies. This aspect is illustrated by its conversion into the bis‐alkyne complex 6 as an unprecedented representation of a cycloaddition catalyst loaded with two substrates molecules. On the other hand, alkylation of 2 with 1 equivalent of cyclohexylmagnesium bromide furnished the unique iron alkyl species 11 with a 14‐electron count, which has no less than four β‐H atoms but is nevertheless stable at low temperature against β‐hydride elimination. In contrast, the exhaustive alkylation of 1 with cyclohexylmagnesium bromide triggers two consecutive C–H activation reactions mediated by a single iron center. The resulting complex has a diene dihydride character in solution ( 15 ), whereas its structure in the solid state is more consistent with an η3‐allyl iron hydride rendition featuring an additional agostic interaction ( 14 ). Finally, the preparation of the cyclopentadienyl iron complex 25 illustrates how an iron‐mediated C–H activation cascade can be coaxed to induce a stereoselective C C bond formation. The structures of all relevant new iron complexes in the solid state are presented. 相似文献
998.
E. Krause W. Limberg A. M. Kharitonov M. D. Brodetsky A. Henze 《Experiments in fluids》1999,26(5):423-436
Supersonic flight of aerospace planes is of marked interest since several flow regimes characterized by different local flow structures have to be flown through. This problem was investigated experimentally for the hypersonic research configuration ELAC 1. The aim of the study was to detect the influence of the rounded leading edge, of the thickness distribution prescribed, and of the Reynolds number, especially on the flow on the leeward side of the configuration. The experiments were carried out in the transonic wind tunnel of Aerodynamisches Institut of RWTH Aachen, at a freestream Mach number Ma ∞=2, a unit Reynolds number of Re ∞=13×106, angles of attack between ?3°?α?10°, and in a wind tunnel of the Institute for Theoretical and Applied Mechanics of the Russian Academy of Sciences in Novosibirsk. The freestream Mach numbers covered in these experiments were varied between 2?Ma ∞?4, freestream Reynolds numbers per unit length between 25×106?Re ∞?56×106 and angles of attack between ?3°?α?10°. Flow visualization studies, measurements of surface pressure distributions and of aerodynamic forces were used to analyze the flow. The results, which will also be compared with numerical data, clearly indicate marked differences in the location of the separation and reattachment lines, and the formation of the primary, secondary and tertiary vortices, for the flow regimes investigated. 相似文献
999.
B. Drapp D. Pauluth J. Krause G. Gauglitz 《Analytical and bioanalytical chemistry》1999,364(1-2):121-127
It is demonstrated that optical transducers can take advantage from the outstanding optical properties of nematic liquid crystals. The measurements point out that the birefringence and the phase transition of a liquid crystal can be exploited for the threshold sensing. For that purpose a device consisting of an orientated liquid crystalline film between two crossed polarizers was used. The nematic liquid crystal was also used as a sensitive coating material on an integrated optical Mach-Zehnder interferometer. The calibration experiments were carried out with volatile organic solvents and different calibration curves were measured for meta-xylene and para-xylene. 相似文献
1000.