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961.
This paper presents results on the rheological behaviour of suspensions of two kinds of TiO2 particles in two different polymer solutions. The particles differ in their hydrophilic or hydrophobic properties. The dispersing
media are a solution of high molecular weight polyisobutylene in decalin and a solution of a low molecular weight polybutene
in decalin. The concentrations of polymer are adjusted in order to get the same zero shear viscosity. The shear viscosity
measurements display an apparent yield stress in some cases. The existence and the values of the yield stress depend on the
volume fraction of solid particles and on the type of particles. The evolution of the intrinsic viscosity and of the maximum
packing fraction vs the shear rate is interpreted in terms of evolution of the size and of the shape of aggregates of particles
under shear. The effect of temperature on the development of the yield stress is also discussed. The results are completed
by microscopic observations. 相似文献
962.
The dynamics of a structurally non-linear two-dimensional airfoil in turbulent flow is investigated numerically using a Monte
Carlo approach. Both the longitudinal and vertical components of turbulence, corresponding to parametric (multiplicative)
and external (additive) excitation, respectively, are modelled. The properties of the airfoil are chosen such that the underlying
non-excited, deterministic system exhibits binary flutter; the loss of stability of the equilibrium point due to flutter then
leads to a limit cycle oscillation (LCO) via a supercritical Hopf bifurcation. For the random system, the results are examined
in terms of the probability structure of the response and the largest Lyapunov exponent. The airfoil response is interpreted
from the point of view of the concepts of D- and P-bifurcations, as defined in random bifurcation theory. It is found that
the bifurcation is characterized by a change in shape of the response probability structure, while no discontinuity in the
variation of the largest Lyapunov exponent with airspeed is observed. In this sense, the trivial bifurcation obtained for
the deterministic airfoil, where the D- and P-bifurcations coincide, appears only as a P-bifurcation for the random case.
At low levels of turbulence intensity, the Gaussian-like bell-shaped bi-dimensional PDF bifurcates into a crater shape; this
is interpreted as a random fixed point bifurcating into a random LCO. At higher levels of turbulence intensity, the post-bifurcation
PDF loses its underlying deterministic LCO structure. The crater is transformed into a two-peaked shape, with a saddle at
the origin. From a more universal point of view, the robustness of the random bifurcation scenario is critiqued in light of
the relative importance of the two components of turbulent excitation. 相似文献
963.
964.
Fatima Bouhtit Mehdi Najar Doua Moussa Agha Rahma Melki Mustapha Najimi Khalid Sadki Noureddine Boukhatem Dominique Bron Nathalie Meuleman Abdellah Hamal Laurence Lagneaux Philippe Lewalle Makram Merimi 《Molecules (Basel, Switzerland)》2021,26(2)
Acute myeloid leukemia (AML) is a cancer of the myeloid lineage of blood cells, and treatment for AML is lengthy and can be very expensive. Medicinal plants and their bioactive molecules are potential candidates for improving human health. In this work, we studied the effect of Ptychotis verticillata (PV) essential oil and its derivatives, carvacrol and thymol, in AML cell lines. We demonstrated that a combination of carvacrol and thymol induced tumor cell death with low toxicity on normal cells. Mechanistically, we highlighted that different molecular pathways, including apoptosis, oxidative, reticular stress, autophagy, and necrosis, are implicated in this potential synergistic effect. Using quantitative RT-PCR, Western blotting, and apoptosis inhibitors, we showed that cell death induced by the carvacrol and thymol combination is caspase-dependent in the HL60 cell line and caspase-independent in the other cell lines tested. Further investigations should focus on improving the manufacturing of these compounds and understanding their anti-tumoral mechanisms of action. These efforts will lead to an increase in the efficiency of the oncotherapy strategy regarding AML. 相似文献
965.
“Hummingbird” Behaviour of N‐Heterocyclic Carbenes Stabilises Out‐of‐Plane Bonding of AuCl and CuCl Units
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Matthieu Teci Dr. Eric Brenner Dr. Dominique Matt Christophe Gourlaouen Loic Toupet 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(31):10997-11000
An N‐heterocyclic carbene substituted by two expanded 9‐ethyl‐9‐fluorenyl groups was shown to bind an AuCl unit in an unusual manner, namely with the Au?X rod sitting out of the plane defined by the heterocyclic carbene unit. As shown by X‐ray studies and DFT calculations, the observed large pitch angle (21°) arises from an easy displacement of the gold(I) atom away from the carbene lone‐pair axis, combined with the stabilisation provided by weak CH???Au interactions involving aliphatic and aromatic H atoms of the NHC wingtips. Weak, intermolecular Cl???H bonds are likely to cooperate with the H???Au interactions to stabilise the out‐of‐plane conformation. A general belief until now was that tilt angles in NHC complexes arise mainly from steric effects within the first coordination sphere. 相似文献
966.
Heteropentanuclear Oxalato‐Bridged nd–4f (n=4, 5) Metal Complexes with NO Ligand: Synthesis,Crystal Structures,Aqueous Stability and Antiproliferative Activity
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Dr. Paul‐Steffen Kuhn B. Sc. Laura Cremer Dr. Anatolie Gavriluta Dr. Katarina K. Jovanović Dr. Lana Filipović Dr. Alfred A. Hummer Dr. Gabriel E. Büchel Dr. Biljana P. Dojčinović Dr. Samuel M. Meier Prof. Dr. Annette Rompel Dr. Siniša Radulović Dr. Jean Bernard Tommasino Dr. Dominique Luneau Prof. Dr. Vladimir B. Arion 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(39):13703-13713
A series of heteropentanuclear oxalate‐bridged Ru(NO)‐Ln (4d–4f) metal complexes of the general formula (nBu4N)5[Ln{RuCl3(μ‐ox)(NO)}4], where Ln=Y ( 2 ), Gd ( 3 ), Tb ( 4 ), Dy ( 5 ) and ox=oxalate anion, were obtained by treatment of (nBu4N)2[RuCl3(ox)(NO)] ( 1 ) with the respective lanthanide salt in 4:1 molar ratio. The compounds were characterized by elemental analysis, IR spectroscopy, electrospray ionization (ESI) mass spectrometry, while 1 , 2 , and 5 were in addition analyzed by X‐ray crystallography, 1 by Ru K‐edge XAS and 1 and 2 by 13C NMR spectroscopy. X‐ray diffraction showed that in 2 and 5 four complex anions [RuCl3(ox)(NO)]2? are coordinated to YIII and DyIII, respectively, with formation of [Ln{RuCl3(μ‐ox)(NO)}4]5? (Ln=Y, Dy). While YIII is eight‐coordinate in 2 , DyIII is nine‐coordinate in 5 , with an additional coordination of an EtOH molecule. The negative charge is counterbalanced by five nBu4N+ ions present in the crystal structure. The stability of complexes 2 and 5 in aqueous medium was monitored by UV/Vis spectroscopy. The antiproliferative activity of ruthenium‐lanthanide complexes 2 – 5 were assayed in two human cancer cell lines (HeLa and A549) and in a noncancerous cell line (MRC‐5) and compared with those obtained for the previously reported Os(NO)‐Ln (5d–4f) analogues (nBu4N)5[Ln{OsCl3(ox)(NO)}4] (Ln=Y ( 6 ), Gd ( 7 ), Tb ( 8 ), Dy ( 9 )). Complexes 2 – 5 were found to be slightly more active than 1 in inhibiting the proliferation of HeLa and A549 cells, and significantly more cytotoxic than 5d–4f metal complexes 6 – 9 in terms of IC50 values. The highest antiproliferative activity with IC50 values of 20.0 and 22.4 μM was found for 4 in HeLa and A549 cell lines, respectively. These cytotoxicity results are in accord with the presented ICP‐MS data, indicating five‐ to eightfold greater accumulation of ruthenium versus osmium in human A549 cancer cells. 相似文献
967.
Sabrina Steinwand Thomas Halbritter Dominique Rastädter Dr. Juan Manuel Ortiz‐Sánchez Prof. Dr. Irene Burghardt Prof. Dr. Alexander Heckel Prof. Dr. Josef Wachtveitl 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(44):15720-15731
Ultrafast UV/Vis pump/probe experiments on ortho‐, meta‐ and para‐hydroxy‐substituted azobenzenes (HO‐ABs), as well as for sulfasalazine, an AB‐based drug, were performed in aqueous solution. For meta‐HO‐AB, AB‐like isomerisation behaviour can be observed, whereas, for ortho‐HO‐AB, fast proton transfer occurs, resulting in an excited keto species. For para‐HO‐AB, considerable keto/enol tautomerism proceeds in the ground state, so after excitation the trans‐keto species isomerises into the cis form. Aided by TD‐DFT calculations, insight is provided into different deactivation pathways for HO‐AB, and reveals the role of hydroxy groups in the photochemistry of ABs, as well as their acetylation regarding sulfasalazine. Hydroxy groups are position‐specific substituents for AB, which allow tuning of the timescale of thermal relaxation, as well as the amount and contribution of the keto species to photochemical processes. 相似文献
968.
Controlled post‐synthesis grafting of thermoresponsive poly(N‐isopropylacrylamide) on mesoporous silica nanoparticles
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Sushilkumar A. Jadhav Ivana Miletto Valentina Brunella Gloria Berlier Dominique Scalarone 《先进技术聚合物》2015,26(9):1070-1075
Ordered mesoporous silica nanoparticles with pore diameter of 5 nm were synthesized by modification of the sol‐gel synthesis method. Post‐synthesis two‐step grafting of thermoresponsive poly(N‐isopropylacrylamide) inside the mesopores of the nanoparticles was carried out by distillation–precipitation polymerization of the methacryloxy‐functionalized mesoporous nanoparticles with N‐isopropylacrylamide monomer. A precise control on the quantity of the grafted polymer was achieved by changing the ratio of monomer to methacryloxy‐functionalized nanoparticles. The polymer‐grafted hybrid nanoparticles obtained were fully characterized by infrared spectroscopy, X‐ray diffraction, dynamic light scattering, transmission electron microscopy, thermal, and gas‐volumetric analyses, which clearly showed presence and thermoresponsive behavior of the polymer inside the mesopores with the preservation of the characteristic mesoporous structure of the nanoparticles. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
969.
Prada C de Rosny J Clorennec D Minonzio JG Aubry A Fink M Berniere L Billand P Hibral S Folegot T 《The Journal of the Acoustical Society of America》2007,122(2):761-768
A rigid 24-element source-receiver array in the 10-15 kHz frequency band, connected to a programmable electronic system, was deployed in the Bay of Brest during spring 2005. In this 10- to 18-m-deep environment, backscattered data from submerged targets were recorded. Successful detection and focusing experiments in very shallow water using the decomposition of the time reversal operator (DORT method) are shown. The ability of the DORT method to separate the echo of a target from reverberation as well as the echo from two different targets at 250 m is shown. An example of active focusing within the waveguide using the first invariant of the time reversal operator is presented, showing the enhanced focusing capability. Furthermore, the localization of the scatterers in the water column is obtained using a range-dependent acoustic model. 相似文献
970.
Saint-Jalmes A Marze S Ritacco H Langevin D Bail S Dubail J Guingot L Roux G Sung P Tosini L 《Physical review letters》2007,98(5):058303
We report the results of fluid transport experiments in aqueous foams under microgravity. Using optical and electrical methods, the capillary motion of the foam fluid and the local liquid fractions are monitored. We show that foams can be continuously wetted up to high liquid fractions ( approximately 0.3), without any bubble motion instabilities. Data are compared to drainage models: For liquid fractions above 0.2, discrepancies are found and identified. These new results on foam hydrodynamics and structure can be useful for other poroelastic materials, such as plants and biological tissues. 相似文献