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81.
We establish some uniqueness and existence results for first-order ordinary differential equations with constant-signed discontinuous nonlinear parts. Several examples are given to illustrate the applicability of our work. 相似文献
82.
The transitions between the low lying crystal field split states A1g and B1g of the Fe2+ ions in pure FeF2 and in the mixed antiferromagnet Fe1-xMnxF2 have been investigated with Raman light scattering. From the Raman polarization rules the lines have been identified as arising from the magnetic excitons associated with the transitions. The energy and the line-width of the strongest line are studied as a function of the concentration x. From the energy measurement we estimate that the single ion anisotropy parameter D of the Fe2+ ions varies from 6.46 cm-1 in pure FeF2 to 8.03 cm-1 in MnF2: Fe. 相似文献
83.
In previous work, (E)-2-enynyl pyridines were reported to yield indolizinyl singlet carbenes through base-catalyzed E/Z isomerization followed by a 5-exo-dig pseudocoarctate cyclization. We report herein that in the presence of ethyl acrylate these carbenes undergo stereoselective cis-cyclopropanation due mainly to electrostatic interactions in the transition state. The scope of this carbene generation scheme has been further explored through the preparation of a symmetric bis(pyridylenyl)alkyne which spontaneously furnished the biindolizine core in a one-pot reaction. Computational characterization of this transformation suggests a highly asynchronous double cyclization. 相似文献
84.
C. González J. I Gutiérrez J. R. González-Velasco A. Cid A. Arranz J. F. Arranz 《Journal of Thermal Analysis and Calorimetry》1996,47(1):93-102
Thermal decomposition of various synthetic manganese oxides (MnO, Mn3O4, Mn2O3, MnOOH) and a natural manganese dioxide (MnO2) from Gabon was studied with the help of termogravimetry in inert, oxidizing and reducing atmospheres. The compounds were characterized by XRD and electrochemical activity was tested by cyclic voltammetry using a carbon paste electrode. The natural manganese dioxide showed the best oxidizing and reducing capacity, confirmed by the lower temperatures of the transitions, the extent of the reactions and electrochemical performance in cyclic voltammograms. 相似文献
85.
R. Perrin M. Braza E. Cid S. Cazin A. Barthet A. Sevrain C. Mockett F. Thiele 《Experiments in fluids》2007,43(2-3):341-355
The flow past a circular cylinder at high Reynolds number is studied by means of PIV, 3C-PIV and Time-Resolved PIV techniques.
One of the goals of this study was to allow comparisons with numerical simulations on a domain identical to that of the experiment.
For this reason, the cylinder was placed in a confined environment, with a high blockage and a low aspect ratio, thereby allowing
computations on a mesh of reasonable size, and avoiding “infinite conditions”. This paper deals with the decomposition of
the flow in a coherent and random parts. To this aim, phase averaged quantities were first obtained using the wall pressure
signal on the cylinder as a trigger signal. This was achieved using both conditional sampling and LSE with similar results.
This decomposition is then analysed using the Time Resolved PIV measurements, as well as by comparison of the contributions
of the organised and turbulent fluctuations to the time-independent Reynolds stress tensor with those estimated from velocity
spectra by interpolation and integration of the continuous part. In agreement with other studies, it is found that the contribution
of the turbulent motion is overestimated as a result of the occurence of phase jitter between the trigger and velocity signal.
A POD analysis was then performed to extract the coherent motion and to compare this decomposition with that obtained by phase
averaging. Similarly to the phase averaging, the POD allows the decomposition of the time-independent stress tensor as the
sum of two contributions corresponding to the first N modes, and the rest of the modes. This decomposition is then analysed by comparing these contributions to those obtained
from the velocity spectra, according to the value N chosen. It is found that these contributions are strongly dependent on N, and the contribution of the first modes greatly overestimate the coherent motion if N is too large. In order to obtain a good decomposition of the flow in coherent and random parts, the difficulty in this case
lies in the choice of the modes. Finally, the POD coefficients of the first two modes are used instead of the pressure signal
to determine the phase of the vortex shedding, and the phase averaging is reconsidered. It is found that the phase averaged
vortices are less smeared by the averaging process, the turbulent stresses better follow the evolution of the vortices, and
the contributions of both coherent and turbulent fluctuations are found to agree well with those evaluated from the velocity
spectra. This enhancement is obtained because the phase angle is determined directly from the velocity fields to be averaged,
thereby reducing the phase-jitter effect. A comparison with a detached eddy simulation is also briefly shown and demonstrates
the high level of agreement obtainable between simulation and experiment, as well as confirming the enhancement of the phase
averaging using this procedure. 相似文献
86.
Lucas Oorlynck Yera Ye. Ussembayev Ingrid Amer Cid Juan Fraire Charlotte Hinnekens Kevin Braeckmans Filip Strubbe 《Particle & Particle Systems Characterization》2023,40(1):2200152
To enable detailed studies of interactions between nanoparticles and their environment and the correlations between various nanoparticle properties, one must go beyond ensemble averages and toward single-particle measurements. However, current methodologies for the single-nanoparticle analysis of charge and size either lack the flexibility to study dynamic processes on the single-particle level or are highly specific and require complex microfluidic devices. In addition, accurate measurements of the electrophoretic mobility (or zeta-potential) based on the optical detection of single nanoparticles remain challenging due to the low photon budget, the required sampling frequency, and the fact that electroosmosis in typical microfluidic devices must be analyzed carefully. In this study, a method is investigated to accurately characterize the electrophoretic mobility of individual nanoparticles and estimate their size by simultaneously analyzing the electrokinetic- and Brownian motion in a simple microfluidic channel. Fast laser scanning excitation and sensitive detection of fluorescent photons enable single-nanoparticle velocimetry experiments in an oscillating electric field at high frame rates. 相似文献
87.
88.
Cid Andre Fidelis de Paula Gomes Yasmin El-Hage Ana Paula Amaral Carolina Marciela Herpich Fabiano Politti Sandra Kalil-Bussadori Tabajara de Oliveira Gonzalez Daniela Aparecida Biasotto-Gonzalez 《Physical Therapy Research》2015,18(1):1-6
Purpose: The aim of the present study was to investigate the effects of massage therapy on the masticatory muscles and occlusal splint usage on quality of life and pain in individuals with sleep bruxism. Method: A randomized, controlled, blinded, clinical trial was conducted involving 78 volunteers aged 18 to 40 years with sleep bruxism. Quality of life and pain assessments were performed. Results: Significant differences (p < 0.05) were found on the physical functioning, general health state, vitality, role emotional and mental health subscales. A large effect size was found for all treatment protocols with regard to pain. The largest effect was found in the combined treatment group. Conclusions: The findings of the present study reveal that the occlusal splint usage alone led to improvements in components of quality of life among individuals with sleep bruxism. Moreover, both treatments (occlusal splint usage and massage therapy on the masticatory muscles) led to a reduction in pain. 相似文献
89.
We report measurements of the nonlinear refractive index, n(2), of nickel oxide nanoparticles (NPs) in toluene at 532 nm. The measurements were performed using the Z-scan technique with 80 ps laser pulses at 7 Hz. Large values of n(2) in the range of 10(-13)-10(-12) cm(2)/W were measured, and negligible two-photon absorption coefficient was estimated for colloids having NP filling fractions in the range of 10(-8)-10(-7). 相似文献
90.
Selective Boryl‐Anion Migration in a Vinyl sp2−sp3 Diborane Induced by Soft Borane Lewis Acids 下载免费PDF全文
Valerio Fasano Dr. Jessica Cid Richard J. Procter Emily Ross Prof. Dr. Michael J. Ingleson 《Angewandte Chemie (International ed. in English)》2018,57(40):13293-13297
An intramolecular 1,2‐boryl‐anion migration from boron to carbon has been achieved by selective activation of the π system in [(vinyl)B2Pin2)]? using “soft” BR3 electrophiles (BR3=BPh3 or 9‐aryl‐BBN). The soft character is key to ensure 1,2‐migration proceeds instead of oxygen coordination/B?O activation. The BR3‐induced 1,2‐boryl‐anion migration represents a triple borylation of a vinyl Grignard reagent using only B2Pin2 and BR3 and forms differentially protected 1,1,2‐triborylated alkanes. Notably, by increasing the steric bulk at the β position of the vinyl Grignard reagent used to activate B2Pin2, 1,2‐boryl‐anion migration can be suppressed in favor of intermolecular {BPin}? transfer to BPh3, thus enabling simple access to unsymmetrical sp2?sp3 diboranes. 相似文献