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381.
Giovanni Batignani Emanuele Pontecorvo Davide Bossini Carino Ferrante Giuseppe Fumero Giulio Cerullo Shaul Mukamel Tullio Scopigno 《Annalen der Physik》2019,531(12)
Illuminating a magnetic material with femtosecond laser pulses induces complex ultrafast dynamical processes. The resulting optically detectable response usually contains contributions from both the optical properties and the magnetic degrees of freedom. Disentangling all the different components concurring to the generation of the total signal is a major challenge of contemporary experimental solid‐state physics. Here, this problem is tackled, addressing the purely optical, nonmagnetic artifacts on the time resolved two‐magnon stimulated Raman spectrum of an antiferromagnet, rationalizing the recent observation on the exchange energy modification upon photo‐excitation. It is demonstrated how the genuine dynamics of the magnetic eigenmode can be disentangled from the nonlinear optical effects, generated by cross phase modulation, on the femtosecond timescale. The introduced approach can be extended for the investigation of <100 fs dynamic processes by means of coherent Raman scattering. 相似文献
382.
Numerical calculation of FSS/RSS transition in highly overexpanded rocket nozzle flows 总被引:1,自引:0,他引:1
Turbulent flow separation in over-expanded rocket nozzles is investigated numerically in a sub-scale parabolic nozzle fed
with cold nitrogen. Depending upon the feeding to ambient pressure ratio either a free shock separation or a restricted shock
separation is computed, with a significant hysteresis between these two flow regimes. This hysteresis was also found in experimental
tests with the same nozzle geometry. The present study is mainly focused on the transition between the two shock separation
patterns. The analysis of the numerical solutions aims to provide clues for the explanation of the hysteresis cycle. 相似文献
383.
Emanuele Nunzio Spadaro 《Archive for Rational Mechanics and Analysis》2009,193(3):659-678
In this note we solve a problem posed by Ball (in Philos Trans R Soc Lond Ser A 306(1496):557–611, 1982) about the uniqueness
of smooth equilibrium solutions to boundary value problems for strictly polyconvex functionals,
where Ω is homeomorphic to a ball.
We give several examples of non-uniqueness. The main example is a boundary value problem with at least two different global
minimizers, both analytic up to the boundary. All these examples are suggested by the theory of minimal surfaces. 相似文献
384.
Colletier JP Sanson B Nachon F Gabellieri E Fattorusso C Campiani G Weik M 《Journal of the American Chemical Society》2006,128(14):4526-4527
The X-ray crystallographic structure of Torpedo californica acetylcholinesterase (TcAChE) in complex with the bifunctional inhibitor NF595, a potentially new anti-Alzheimer drug, has been solved. For the first time in TcAChE, a major conformational change in the peripheral-site tryptophan residue is observed upon complexation. The observed conformational flexibility highlights the dynamic nature of protein structures and is of importance for structure-based drug design. 相似文献
385.
Michela Giuliano Claudia Pellerito Adriana Celesia Tiziana Fiore Sonia Emanuele 《Molecules (Basel, Switzerland)》2021,26(16)
Organotin(IV) compounds are a class of non-platinum metallo-conjugates exhibiting antitumor activity. The effects of different organotin types has been related to several mechanisms, including their ability to modify acetylation protein status and to promote apoptosis. Here, we focus on triorganotin(IV) complexes of butyric acid, a well-known HDAC inhibitor with antitumor properties. The conjugated compounds were synthesized and characterised by FTIR spectroscopy, multi-nuclear (1H, 13C and 119Sn) NMR, and mass spectrometry (ESI-MS). In the triorganotin(IV) complexes, an anionic monodentate butyrate ligand was observed, which coordinated the tin atom on a tetra-coordinated, monomeric environment similar to ester. FTIR and NMR findings confirm this structure both in solid state and solution. The antitumor efficacy of the triorganotin(IV) butyrates was tested in colon cancer cells and, among them, tributyltin(IV) butyrate (BT2) was selected as the most efficacious. BT2 induced G2/M cell cycle arrest, ER stress, and apoptotic cell death. These effects were obtained using low concentrations of BT2 up to 1 μM, whereas butyric acid alone was completely inefficacious, and the parent compound TBT was poorly effective at the same treatment conditions. To assess whether butyrate in the coordinated form maintains its epigenetic effects, histone acetylation was evaluated and a dramatic decrease in acetyl-H3 and -H4 histones was found. In contrast, butyrate alone stimulated histone acetylation at a higher concentration (5 mM). BT2 was also capable of preventing histone acetylation induced by SAHA, another potent HDAC inhibitor, thus suggesting that it may activate HDACs. These results support a potential use of BT2, a novel epigenetic modulator, in colon cancer treatment. 相似文献
386.
Determination of trace level of selenium and mercury in photographic emulsions by atomic spectroscopy techniques 总被引:1,自引:0,他引:1
Trace level of selenium and mercury in photographic emulsion are used to improve photographic properties. The presence of silver halide in photographic emulsion does not allow the application of the most common analytical methods such as Hydride Generation Atomic Absorption Spectrometry (HG-AAS) and cold vapour Atomic Absorption Spectrometry (CV-AAS). Besides, silver removal was not quantitative, leading to a significant loss of the analytes and low reproducibility. The present work suggest the use of inductively coupled plasma Atomic Emission Spectrometry (ICP-AES) equipped with Ultrasonic Nebulizer (USN) for direct aqueous samples analysis at microgram l-1 level (d.l. 5.1 ppb for Hg and 6.1 ppb for Se). 相似文献
387.
Emanuele Pacifici 《Archiv der Mathematik》2005,84(1):1-10
Let G be a finite group, and V a finite-dimensional semisimple G-module over a finite field. Assume that V is endowed with a nonsingular bilinear form which is symmetric or symplectic, and which is invariant under the action of G. In this setting, we compute the number of anisotropic simple submodules of V.Received: 25 May 2004 相似文献
388.
Paolo?ButtàEmail author Emanuele?Caglioti Carlo?Marchioro 《Communications in Mathematical Physics》2004,249(2):353-382
We consider an infinite Hamiltonian system in one space dimension, given by a charged particle subjected to a constant electric field and interacting with an infinitely extended system of particles. We discuss conditions on the particle/medium interaction which are necessary for the charged particle to reach a finite limiting velocity. We assume that the background system is initially in an equilibrium Gibbs state and we prove that for bounded interactions the average velocity of the charged particle increases linearly in time. This statement holds for any positive intensity of the electric field, thus contradicting Ohms law.Work partially supported by the GNFM-INDAM and the Italian Ministry of the University. 相似文献
389.
Roberto Maffei Facino Anna Sparatore Marina Carini Bruno Gioia Emanuele Arlandini Luigi Franzoi 《Journal of mass spectrometry : JMS》1991,26(11):951-955
The mass spectral fragmentation of echinacoside, a pharmacologically active caffeoyl-glycoside isolated from Echinacea angustifolia roots, has been investigated using different soft-ionization techniques, field desorption and fast atom bombardment (positive and negative ions) mass Spectrometry. Both ionization modes are successful in molecular mass determination and furnish approximately equivalent structural information. A fast atom bombardment tandem mass spectrometry approach (negative ions) was developed for the study of the fragmentation pathways and for the detection of echinacoside in crude plant extracts. The results demonstrate the usefulness of this technique for the rapid search of this important caffeoyl-glucoside directly in natural complex matrices. 相似文献
390.
A. Agnetis P.B. Mirchandani D. Pacciarelli A. Pacifici 《Computational & Mathematical Organization Theory》2000,6(2):191-217
We consider the scenario where two users compete to perform their respective jobs on a common set of resources. The job for each user has a due-date and the cost function associated with the due-date is quasi-convex (i.e., it has a single local minimum). We characterize the set of nondominated schedules over which the users may negotiate and develop a polynomial algorithm to find this nondominated set. 相似文献