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81.
Dr. Bethany R. Hood Dr. Yovan de Coene Afonso V. Torre Do Vale Froes Dr. Claire F. Jones Dr. Pierre Beaujean Dr. Vincent Liégeois Dr. Fraser MacMillan Prof. Benoît Champagne Prof. Koen Clays Dr. John Fielden 《Angewandte Chemie (International ed. in English)》2023,62(5):e202215537
Electrochemically switched 2nd order non-linear optical responses have been demonstrated for the first time in polyoxometalates (POMs), with an arylimido-derivative showing a leading combination of high on/off contrast (94 %), high visible transparency, and cyclability. Spectro-electrochemical and TD-DFT studies indicate that the switch-off results from weakened charge transfer (CT) character of the electronic transitions in the reduced state. This represents the first study of an imido-POM reduced state, and demonstrates the potential of POM hybrids as electrochemically activated molecular switches. 相似文献
82.
R. Broda P. J. Daly Z. W. Grabowski H. Helppi M. Kortelahti J. McNeill R. V. F. Janssens R. D. Lawson D. C. Radford J. Blomqvist 《Zeitschrift für Physik A Hadrons and Nuclei》1985,321(2):287-295
The level structure of theN=81 nucleus147Dy has been studied byγ-ray spectroscopy following reactions of 230–250 MeV58,60Ni beams on89Y and90,92Zr targets. Yrast and near-yrast levels in147Dy above the known 59-s 11/2? state are established up to ~3.7 MeV; they include isomeric levels at 2,681, 3,407 and 3,650 keV. Guided by the results of shell model calculations, we interpret most of the observed level as senioritythree states arising from the coupling ofs 1/2,d 3/2, andh 11/2 neutron holes withπh 11/2 2. 相似文献
83.
Koen Thas 《Designs, Codes and Cryptography》2002,25(3):247-253
Suppose
is a generalized quadrangle (GQ) of order
, with a regular point. Then there is a net which arises from this regular point. We prove that if such a net has a proper subnet with the same degree as the net, then it must be an affine plane of order t. Also, this affine plane induces a proper subquadrangle of order t containing the regular point, and we necessarily have that
. This result has many applications, of which we give one example. Suppose
is an elation generalized quadrangle (EGQ) of order
, with elation point p. Then
is called a skew translation generalized quadrangle (STGQ) with base-point p if there is a full group of symmetries about p of order t which is contained in the elation group. We show that a GQ
of order s is an STGQ with base-point p if and only if p is an elation point which is regular. 相似文献
84.
Gu R Robeyns K Van Meervelt L Toppet S Dehaen W 《Organic & biomolecular chemistry》2008,6(14):2484-2487
Novel indolo[3,2-b]carbazole derivatives and a chromogenic-sensing 5,12-dihydroindolo[3,2-b]carbazole have been synthesized starting from tetra-tert-butylated 6,12-diaryl-5,11-dihydroindolo[3,2-b]carbazoles, which were prepared via an efficient tert-butylation of 6,12-diaryl-5,11-dihydroindolo[3,2-b]carbazoles. 相似文献
85.
Mathias Kersemans Klaas Allaer Wim Van Paepegem Koen Van Den Abeele Lincy Pyl Filip Zastavnik Hugo Sol Joris Degrieck 《Experimental Mechanics》2014,54(9):1673-1685
A novel method is introduced for the measurement of a 3D strain field by exploiting the interaction between ultrasound waves and geometrical characteristics of the insonified specimen. First, the response of obliquely incident harmonic waves to a deterministic surface roughness is utilized. Analysis of backscattered amplitudes in Bragg diffraction geometry then yields a measure for the in-plane strain field by mapping any shift in angular dependency. Secondly, the analysis of the reflection characteristics of normal incident pulsed waves in frequency domain provides a measure of the out-of-plane normal strain field component, simply by tracking any change in the stimulation condition for a thickness resonance. As such, the developed ultrasonic strain gauge yields an absolute, contactless and single-sided mapping of a local 3D strain field, in which both sample preparation and alignment procedure are needless. Results are presented for cold-rolled DC06 steel samples onto which skin passing of the work rolls is applied. The samples have been mechanically loaded, introducing plastic strain levels ranging from 2 % up to 35 %. The ultrasonically measured strains have been validated with various other strain measurement techniques, including manual micrometer, longitudinal and transverse mechanical extensometer and optical mono- and stereovision digital image correlation. Good agreement has been obtained between the ultrasonically determined strain values and the results of the conventional methods. As the ultrasonic strain gauge provides all three normal strain field components, it has been employed for the extraction of Lankford ratios at different applied longitudinal plastic strain levels, revealing a strain dependent plastic anisotropy of the investigated DC06 steel sheet. 相似文献
86.
Władysław Piotrowski Koen Lodefier Slawomir Kubacki Witold Elsner Erik Dick 《Flow, Turbulence and Combustion》2008,81(3):369-394
The present paper evaluates two unsteady transition modelling approaches: the prescribed unsteady intermittency method PUIM,
developed at Cambridge University and the dynamic unsteady intermittency method developed at Ghent University. The methods
are validated against experimental data for the N3-60 steam turbine stator profile for steady and for unsteady inlet flow
conditions. The characteristic features of the test case are moderately high Reynolds number and high inlet turbulence intensity,
which causes bypass transition. The tested models rely both on the intermittency parameter and are unsteady approaches. In
the prescribed method, the time-dependent intermittency distribution is obtained from integral relations. In the dynamic method,
the intermittency distribution follows from time-dependent differential equations. For unsteady computations, self-similar
wake profiles are prescribed at the inlet of the computational domain. Joint validation of the prescribed and the dynamic
unsteady intermittency models against experimental data shows that both methods are able to reproduce the global features
of the periodical evolution of the boundary layer under the influence of a periodically impinging wake. The overall quality
of the dynamic method is better than that of the prescribed method. 相似文献
87.
Gerrit K. Janssens Kenneth Sörensen Wout Dullaert 《Mathematical and Computer Modelling》2009,49(3-4):563-572
Stochastic marked graphs, a special class of stochastic timed Petri nets, are used for modelling and analyzing decision-free dynamic systems with uncertainties in timing. The model allows evaluating the performance of such systems under a cyclic process. Given the probabilistic characteristics of the transition times, the cycle time of the system can be determined from the initial marking. In this contribution, we compute an upper bound on the cycle time of a stochastic marked graph in case the probabilistic characteristics of the transition times are not fully specified. 相似文献
88.
Jurgen Sleven Thomas Cardinaels Koen Binnemans Daniel Guillon Bertrand Donnio 《Liquid crystals》2002,29(11):1425-1433
This paper deals with the synthesis of vanadyl phthalocyanines substituted with eight alkoxy chains in the peripheral (2, 3, 9, 10, 16, 17, 23, 24) positions. The alkoxy chain length was varied, and octa-octyloxy (C8H17O), octa-dodecyloxy (C12H25O) and octa-hexadecyloxy (C16H33O) substituted vanadyl phthalocyanine complexes were prepared. Studies by polarizing optical microscopy and small angle X-ray diffraction (XRD) revealed that all the complexes are liquid crystalline and that these metallomesogens exhibit a columnar phase. The symmetry of the 2D lattice is rectangular, with a c2mm space group, as determined by the indexation of the XRD reflections; hence a rectangular columnar phase (Colr) was assigned. A double periodicity, although weak, along the axis of the columns was found, which indicates some degree of pairing or dimerization. A tentative explanation based on an antiferroelectric stacking is given. Transition enthalpies were determined by differential scanning calorimetry. The compounds start to decompose above 250°C before reaching the clearing temperatures. A significant bathochromic shift of the Q-band in the UV/Vis spectra of the vanadyl complexes compared with the metal-free ligands and other metallophthalocyanines (M=CoII, NiII, CuII, ZnII) was also observed. 相似文献
89.
The synthesis and liquid crystalline properties of lanthanide complexes with different but structurally related Schiff's base ligands are described. The complexes all contain nitrate counterions and have the stoichiometry [Ln(LH) 3 (NO 3 ) 3 ], where Ln is a trivalent rare-earth ion (La, Nd, Gd or Ho) and LH is a Schiff's base ligand. None of the Schiff's base ligands exhibits mesomorphism, but some of the complexes do (SmA phase). It is shown that the presence or absence and the position of substituents on the ligand determine whether or not the complexes show mesomorphism. The thermal behaviour of these compounds has been investigated by hot stage polarizing microscopy and differential scanning calorimetry. 相似文献
90.
We give an example of a projection which maps two Gibbs measures for the same interaction into Gibbs measures for different interactions. As a corollary we find a case where by decimation a non-Gibbsian measure is transformed into a Gibbs measure. 相似文献