Results 91 to 100 of about 3,971 (260)

Investigation of Axial–Torsional Vibration Characteristics and Vibration Mitigation Mechanism in Compound Percussive Drilling

Applied Sciences
Severe drill string vibrations, particularly stick–slip, significantly compromise drilling efficiency and tool longevity in deep hard formations. Compound percussive drilling (CPD) has emerged as a promising technique to mitigate these vibrations and ...
Wei Wang, Boyu Guo, Gonghui Liu, Chunqing Zha, Tian Chen, Jun Li   +5 more
doaj   +1 more source

The roles of side chains in Y6‐series non‐fullerene acceptors for high‐performance organic solar cells

Bulletin of the Korean Chemical Society, EarlyView.
The development of organic solar cells (OSCs) has been driven by structural modifications of Y6‐series non‐fullerene acceptors. In particular, side‐chain engineering regulates solubility, molecular packing, and energy levels, enabling efficiencies to increase from 15.7% to over 20%.
Peddaboodi Gopikrishna, Bomi Kim, Jongnam Park, BongSoo Kim   +3 more
wiley   +1 more source

N─H or O─H Bond Activation With a Bicyclic Si4 Ring Compound

Chemistry – A European Journal, EarlyView.
The bicyclic Si4 ring compound with zwitterionic character reacts with NH3, H2O, and selected alcohols to give functionalized saturated silicon rings, siliconoid clusters with unsubstituted Si atoms, or simple 1,3‐addition products. The experimentally observed reactivity could be rationalized based on results from mechanistic calculations employing ...
Michael Quest, Florian Schreiner, Alexander Hepp, Constantin G. Daniliuc, Kasperi M. Salonen, Janne Körkkö, Heikki M. Tuononen, Felicitas Lips   +7 more
wiley   +1 more source

Dynamic active torque coordination strategy for torsional vibration suppression in wind turbines during grid fault recovery

International Journal of Electrical Power & Energy Systems
When the grid fault occurs, wind turbines are required to possess fault ride-through (FRT) capability and rapidly restore active power after fault clearance.
Cai Guang, Yan Xiangwu, Zhang Shurui, Ren Haoyang, Jia Jiaoxin, Zhou Fan   +5 more
doaj   +1 more source

Modular One‐Pot Access to π‐Expanded Tetrakis(Phenothiazinyl)‐Silanes With Broadly Tunable Redox and Emission Properties

Chemistry – A European Journal, EarlyView.
A library of 21 tetrakis(phenothiazinyl)‐substituted silanes with broadly variable substituent decoration, which are fully reversible multistage redox systems with intense tunable emission from deep blue to yellow–green (441–533 nm), was rapidly synthesized by bromine–lithium exchange/borylation–Suzuki coupling of tetrakis(4‐bromophenyl)silane or by ...
Thomas P. M. Merke, Lysander Presser, Leonard Karl, Christian Ganter, Thomas J. J. Müller   +4 more
wiley   +1 more source

Torsional vibration

, 2012
Torsional vibration can be broadly described as the angular vibration of any object as a result of applied torque. It can be defined specifically as the periodic motion corresponding to a shaft, where the shaft is twisted about its axis, alternating from one direction to the other.
openaire   +1 more source

Interplay of Bridge Topology and Conformation in Phenylene‐Bridged Trityl Diradicals

Chemistry – A European Journal, EarlyView.
We present a meta‐phenylene‐bridged trityl diradical that exhibits an unexpectedly weak antiferromagnetic exchange coupling J with a strong environment‐dependent magnitude. Combined VSM, EPR, DFT, and MD studies reveal that structural flexibility modulates σ‐, π‐, and through‐space exchange contributions, highlighting the crucial role of geometry in ...
Kevin Lars Kopp, Tobias Hett, Andrea Pellegrini, Stefan Grimme, Olav Schiemann   +4 more
wiley   +1 more source

Syntheses and Properties of Pentafluoroethylplumbanes in the Oxidation States +II, +III, and +IV

Chemistry – A European Journal, EarlyView.
Syntheses of pentafluoroethyl substituted plumbanes in the formal oxidation states +II, +III, and +IV are reported. The compounds were characterized by multinuclear NMR spectroscopy, including 207Pb NMR spectroscopy, mass spectrometry and single‐crystal x‐ray diffraction experiments. ABSTRACT Mono‐, bis‐, and tris(pentafluoroethyl)plumbanes of the type
Michael Grasse, Lukas Hartmann, Beate Neumann, Hans‐Georg Stammler, Berthold Hoge   +4 more
wiley   +1 more source

Raman Optical Activity as a Tool to Monitor Polynucleotide Conformation in Solutions

Chemistry – A European Journal, EarlyView.
Raman optical activity (ROA) studies of nucleic acids have been hindered by limited computational tools to link the spectra to the structure. The study shows that accurate density functional simulations are possible for model nucleotides, bringing more information about molecular geometry and dynamics in solutions.
Mohammed Siddhique Para Kkadan, Josef Kapitán, Jiří Kessler, Ondřej Zapletal, Valery Andrushchenko, Petr Bouř   +5 more
wiley   +1 more source

Electrochemiluminescence of Heteroleptic Iridium(III) Complexes Featuring Substituted 2,4‐diphenylpyridinato Ligands

Chemistry – A European Journal, EarlyView.
Five heteroleptic iridium(III) complexes bearing cyclometalated 2,4‐diphenylpyridinato ligands were synthesized and their electrochemiluminescence (ECL) investigated. Two different coreactants were evaluated: tri‐n‐propylamine and benzoyl peroxide under anodic and cathodic potentials, respectively.
Ovini Jayawardana, El M. S. Martin, Oliver G. Stansfield, Egan H. Doeven, Carol Hua, Timothy U. Connell, Paul S. Francis   +6 more
wiley   +1 more source