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41.
Dennis Schnfeld Dilip Chalissery Franziska Wenz Marius Specht Chris Eberl Thorsten Pretsch 《Molecules (Basel, Switzerland)》2021,26(3)
For soft robotics and programmable metamaterials, novel approaches are required enabling the design of highly integrated thermoresponsive actuating systems. In the concept presented here, the necessary functional component was obtained by polymer syntheses. First, poly(1,10-decylene adipate) diol (PDA) with a number average molecular weight Mn of 3290 g·mol−1 was synthesized from 1,10-decanediol and adipic acid. Afterward, the PDA was brought to reaction with 4,4′-diphenylmethane diisocyanate and 1,4-butanediol. The resulting polyester urethane (PEU) was processed to the filament, and samples were additively manufactured by fused-filament fabrication. After thermomechanical treatment, the PEU reliably actuated under stress-free conditions by expanding on cooling and shrinking on heating with a maximum thermoreversible strain of 16.1%. Actuation stabilized at 12.2%, as verified in a measurement comprising 100 heating-cooling cycles. By adding an actuator element to a gripper system, a hen’s egg could be picked up, safely transported and deposited. Finally, one actuator element each was built into two types of unit cells for programmable materials, thus enabling the design of temperature-dependent behavior. The approaches are expected to open up new opportunities, e.g., in the fields of soft robotics and shape morphing. 相似文献
42.
Iwahara J Tang C Marius Clore G 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2007,184(2):185-195
The use of (1)H transverse paramagnetic relaxation enhancement (PRE) has seen a resurgence in recent years as method for providing long-range distance information for structural studies and as a probe of large amplitude motions and lowly populated transient intermediates in macromolecular association. In this paper we discuss various practical aspects pertaining to accurate measurement of PRE (1)H transverse relaxation rates (Gamma(2)). We first show that accurate Gamma(2) rates can be obtained from a two time-point measurement without requiring any fitting procedures or complicated error estimations, and no additional accuracy is achieved from multiple time-point measurements recorded in the same experiment time. Optimal setting of the two time-points that minimize experimental errors is also discussed. Next we show that the simplistic single time-point measurement that has been commonly used in the literature, can substantially underestimate the true value of Gamma(2), unless a relatively long repetition delay is employed. We then examine the field dependence of Gamma(2), and show that Gamma(2) exhibits only a very weak field dependence at high magnetic fields typically employed in macromolecular studies. The theoretical basis for this observation is discussed. Finally, we investigate the impact of contamination of the paramagnetic sample by trace amounts (5%) of the corresponding diamagnetic species on the accuracy of Gamma(2) measurements. Errors in Gamma(2) introduced by such diamagnetic contamination are potentially sizeable, but can be significantly reduced by using a relatively short time interval for the two time-point Gamma(2) measurement. 相似文献
43.
Marius Schmidt 《Synchrotron Radiation News》2015,28(6):25-30
Serial femtosecond crystallography with biological macromolecules is a rapidly developing method tailored to the immense brilliance of the emerging free electron lasers for hard X-rays (X-ray FELs). Recently, the first successful time-resolved serial femtosecond crystallographic experiment at near atomic resolution was conducted at the Linac Coherent Light Source. The X-ray FEL-based experiments will trigger new developments not only at the X-ray FELs, but also at existing synchrotron light sources. This review will attempt to summarize some of the most important experiments to date and give a brief outlook on what to expect. 相似文献
44.
Photoionization and Pyrolysis of a 1,4‐Azaborinine: Retro‐Hydroboration in the Cation and Identification of Novel Organoboron Ring Systems 下载免费PDF全文
Fabian Holzmeier Dipl.‐Chem. Melanie Lang Dr. Patrick Hemberger Dr. Andras Bodi Dipl.‐Chem. Marius Schäfer Dr. Rian D. Dewhurst Prof. Dr. Holger Braunschweig Prof. Dr. Ingo Fischer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(31):9683-9692
The photoionization and dissociative photoionization of 1,4‐di‐tert‐butyl‐1,4‐azaborinine by means of synchrotron radiation and threshold photoelectron photoion coincidence spectroscopy is reported. The ionization energy of the compound was determined to be 7.89 eV. Several low‐lying electronically excited states in the cation were identified. The various pathways for dissociative photoionization were modeled by statistical theory, and appearance energies AE0K were obtained. The loss of isobutene in a retro‐hydroboration reaction is the dominant pathway, which proceeds with a reverse barrier. Pyrolysis of the parent compound in a chemical reactor leads to the generation of several yet unobserved boron compounds. The ionization energies of the C4H6BN isomers 1,2‐ and 1,4‐dihydro‐1,4‐azaborinine and the C3H6BN isomer 1,2‐dihydro‐1,3‐azaborole were determined from threshold photoelectron spectra. 相似文献
45.
Total Synthesis of the Anti‐inflammatory and Pro‐resolving Lipid Mediator MaR1n−3 DPA Utilizing an sp3–sp3 Negishi Cross‐Coupling Reaction 下载免费PDF全文
Jørn Eivind Tungen Dr. Marius Aursnes Dr. Jesmond Dalli Dr. Hildur Arnardottir Prof. Dr. Charles Nicholas Serhan Prof. Dr. Trond Vidar Hansen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(45):14575-14578
The first total synthesis of the lipid mediator MaR1n?3 DPA ( 5 ) has been achieved in 12 % overall yield over 11 steps. The stereoselective preparation of 5 was based on a Pd‐catalyzed sp3–sp3 Negishi cross‐coupling reaction and a stereocontrolled Evans–Nagao acetate aldol reaction. LC‐MS/MS results with synthetic material matched the biologically produced 5 . This novel lipid mediator displayed potent pro‐resolving properties stimulating macrophage efferocytosis of apoptotic neutrophils. 相似文献
46.
Improving Site‐Directed RNA Editing In Vitro and in Cell Culture by Chemical Modification of the GuideRNA 下载免费PDF全文
Paul Vogel Marius F. Schneider Jacqueline Wettengel Dr. Thorsten Stafforst 《Angewandte Chemie (International ed. in English)》2014,53(24):6267-6271
Adenosine‐to‐inosine deamination can be re‐addressed to user‐defined mRNAs by applying phosphothioate/2′‐methoxy‐modified guideRNAs. Dense chemical modification of the guideRNA clearly improves performance of the covalent conjugates inside the living cell. Furthermore, careful positioning of a few modifications controls editing selectivity in vitro and was exploited for the challenging repair of the Factor 5 Leiden missense mutation. 相似文献
47.
Characterizing Methyl‐Bearing Side Chain Contacts and Dynamics Mediating Amyloid β Protofibril Interactions Using 13Cmethyl‐DEST and Lifetime Line Broadening 下载免费PDF全文
Dr. Nicolas L. Fawzi Dr. David S. Libich Dr. Jinfa Ying Dr. Vitali Tugarinov Dr. G. Marius Clore 《Angewandte Chemie (International ed. in English)》2014,53(39):10345-10349
Many details pertaining to the formation and interactions of protein aggregates associated with neurodegenerative diseases are invisible to conventional biophysical techniques. We recently introduced 15N dark‐state exchange saturation transfer (DEST) and 15N lifetime line‐broadening to study solution backbone dynamics and position‐specific binding probabilities for amyloid β (Aβ) monomers in exchange with large (2–80 MDa) protofibrillar Aβ aggregates. Here we use 13Cmethyl DEST and lifetime line‐broadening to probe the interactions and dynamics of methyl‐bearing side chains in the Aβ‐protofibril‐bound state. We show that all methyl groups of Aβ40 populate direct‐contact bound states with a very fast effective transverse relaxation rate, indicative of side‐chain‐mediated direct binding to the protofibril surface. The data are consistent with position‐specific enhancements of 13Cmethyl‐${R{{{\rm tethered}\hfill \atop 2\hfill}}}$ values in tethered states, providing further insights into the structural ensemble of the protofibril‐bound state. 相似文献
48.
Janina A. Werra Marius A. Wünsche Patrick Rathmann Paul Mehlmann Pawel Löwe Fabian Dielmann 《无机化学与普通化学杂志》2020,646(13):794-799
Phosphoniumylidyl and phosphazenyl groups are effective substituents to increase the electron-donating ability of tertiary phosphines. However, the influence of structural variations among those substituents on the electronic properties of the phosphines is little explored. Herein, we show that protonation of the ylidic carbon atom of phosphoniumylidyl phosphines increases the Tolman electronic parameter (TEP) by ΔTEP = 16.0–18.8 cm–1. Furthermore, phosphazenyl phosphines were synthesized with isopropyl groups (NP{iPr}3) and tetramethylguanidino groups (NP{tmg}3) at the phosphonium center. Determination of their TEP values reveals a remarkable low substituent parameter of χ = –18.5 cm–1 for the NP(tmg)3 group. In addition, we prepared the corresponding gold(I) complexes and determined their solid-state structures using single-crystal X-ray diffraction studies to analyze the steric profile of the new phosphine ligands. 相似文献
49.
Kathrin Brmmel Sarah Maskri Ivan Maisuls Christian Paul Konken Marius Rieke Zoltan Peth Cristian A. Strassert Oliver Koch Albrecht Schwab Bernhard Wünsch 《Angewandte Chemie (International ed. in English)》2020,59(21):8277-8284
Small‐molecule probes for the in vitro imaging of KCa3.1 channel‐expressing cells were developed. Senicapoc, showing high affinity and selectivity for the KCa3.1 channels, was chosen as the targeting component. BODIPY dyes 15 – 20 were synthesized and connected by a CuI‐catalyzed azide–alkyne [3+2]cycloaddition with propargyl ether senicapoc derivative 8 , yielding fluorescently labeled ligands 21 – 26 . The dimethylpyrrole‐based imaging probes 25 and 26 allow staining of KCa3.1 channels in NSCLC cells. The specificity was shown by removing the punctate staining pattern by pre‐incubation with senicapoc. The density of KCa3.1 channels detected with 25 and by immunostaining was identical. The punctate structure of the labeled channels could also be observed in living cells. Molecular modeling showed binding of the senicapoc‐targeting component towards the binding site within the ion channel and orientation of the linker with the dye along the inner surface of the ion channel. 相似文献
50.
Marius Tucsnak 《Mathematical Methods in the Applied Sciences》1996,19(11):897-907
We consider a non-linear plate equation of Bernoulli–Euler type with a locally distributed damping term. Our main result asserts that if the damping is effective in a neighbourhood of the boundary then the energy decays exponentially. The method we use is a combination of multiplier techniques and of a compactness-uniqueness argument. 相似文献