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51.
Cristofher Victor Vivas Palomares Yan Borges Barreto Natalia Marchesan Bexiga Sergio Hiroshi Toma Jonnatan Julival dos Santos Koiti Araki Adriano Mesquita Alencar Antonio Carlos Bloise 《Particle & Particle Systems Characterization》2023,40(4):2200191
The macrophage time-dependent metabolic profile changing basal metabolism triggered by nanoparticles can be obtained and used to improve wound healing treatments. Herein this study demonstrates that metabolic status responds systematically to cytotoxicity manipulation, providing an interesting way of cellular control. Nuclear magnetic resonance (NMR) based metabolomics and cytotoxic assays are used to study RAW 264.7 cells exposed to AgNPs at different concentrations and incubation times. Cytotoxicity data show a slight decrease in cellular expansion rates accompanied by morphological changes in cells. Metabolomics show that despite the glycolytic activity of treated and non-treated cells remains unchanged; however, only the treated cells present a rich Citrate environment signaling up-regulation of Tricarboxylic-Acid-Cycle (TCA). Cells choose aerobic routes instead of anaerobic ones to produce energy and self-regulate their amino acid metabolism to balance TCA. Choline metabolism is down-regulated once its sub-products, Betaine and Glycine, are reduced, thus compromising Creatine synthesis. Phospholipid metabolism is down-regulated due to the decreasing of Phosphocholine and Sn-Glycerol-3-PC, in agreement with the cytotoxicity results. Pyroglutamate decreases in treated cells, signaling different levels of oxidative stress. These analytical tools can characterize AgNPs-treatments, even distinguishing dose and time dependencies. Therefore, the fine-tuning of exposition parameters can modulate cellular activity to achieve better wound healing. 相似文献
52.
Hiroshi Kimura Koichiro Aikawa Yuichi Masubuchi Jun-ichi Takimoto K. Koyama Keiji Minagawa 《Rheologica Acta》1998,37(1):54-60
The mechanism of the electrorheological (ER) effect in two types of liquid crystalline polymer (LCP)/dimethylsiloxane (DMS)
blends was investigated by rheological measurements and by structure observation under electric field and shear flow. The
results show that the phase structures of these immiscible blends can be categorized into slipping (low viscosity) and non-slipping
(high viscosity) states. In the non-slipping state, higher viscosity LCP domains connect the electrodes. In the slipping state,
on the other hand, LCP domains do not connect the electrodes and the shear is mainly confined in the lower viscosity DMS domains.
The ER effect (electrically induced viscosity increase) originates from the electrically induced slipping to non-slipping
transition. In one of the blends, the ER effect occurs only at high shear rate, since this blend is in non-slipping state
even under no field if the shear rate is low.
Received: 29 April 1997 Accepted: 3 November 1997 相似文献
53.
Linear and nonlinear viscoelastic properties were examined for aqueous suspensions of monodisperse poly(methyl methacrylate-co-styrene) (MS) particles having the radius a
0
=45 nm and the volume fractions φ=0.428−0.448. These particles had surface charges and the resulting electrostatic surface
layer (electric double layer) had a thickness of ts=5.7 nm. At low frequencies in the linear viscoelastic regime, the MS particles behaved approximately as the Brownian hard
particles having an effective radius a
eff=a
0 + ts, and the dependence of their zero-shear viscosity η0 on an effective volume fraction φeff (={a
eff/a
0}3φ) agreed with the φ dependence of η0 of ideal hard-core silica suspensions. In a range of φeff < 0.63, this φeff dependence was well described by the Brady theory. However, the φeff dependence of the high-frequency plateau modulus was weaker and the terminal relaxation mode distribution was narrower for
the MS suspensions than for the hard-core suspensions. This result suggested that the electrostatic surface layer of the MS
particles was soft and penetrable (at high frequencies). In fact, this “softness” was more clearly observed in the nonlinear
regime: the nonlinear damping against step strain was weaker and the thinning under steady shear was less significant for
the MS suspension than for the hard-core silica suspensions having the same φeff. These weaker nonlinearities of the concentrated MS particles with φeff∼ 0.63 (maximum volume fraction for random packing) suggested that the surface layers of those particles were mutually penetrating
to provide the particles with a rather large mobility.
Received: 10 July 2001 Accepted: 2 November 2001 相似文献
54.
Hiroshi Niino 《Fluid Dynamics Research》1988,3(1-4):407-414
Inertial stability of a vertical shear layer (Stewartson E1/4-layer) on the sidewall of a cylindrical tank with respect to stationary axisymmetric perturbations is inverstigated by means of a linear theory. The stability is determined by two non-dimensional parameters, the Rossby number Ro = U/2ΩL and Ekman number E = v/ΩH2, where U and L = (E/4)1/4H are the characteristic velocity and width of the shear layer, respectively, Ω the angular velocity of the basic rotation, v the kinematic viscosity and H the depth of the tank.
For a given Ekman number, the flow is more unstable for larger values of the Rossby number. For E = 10−4, which is a typical value of the Ekman number realized in rotating tank experiments, the critical Rossby number Roc for instability and the critical axial wavenumber mc non-dimensionalized by L−1 are found to be 1.3670 and 8.97, respectively. The value of Roc increases and that of mc decreases with increasing E. 相似文献
55.
In this paper, we investigate theoretically and experimentally dynamics of a buckled beam under high-frequency excitation.
It is theoretically predicted from linear analysis that the high-frequency excitation shifts the pitchfork bifurcation point
and increases the buckling force. The shifting amount increases as the excitation amplitude or frequency increases. Namely,
under the compressive force exceeding the buckling one, high-frequency excitation can stabilize the beam to the straight position.
Some experiments are performed to investigate effects of the high-frequency excitation on the buckled beam. The dependency
of the buckling force on the amounts of excitation amplitude and frequency is compared with theoretical results. The transient
state is observed in which the beam is recovered from the buckled position to the straight position due to the excitation.
Furthermore, the bifurcation diagrams are measured in the cases with and without high-frequency excitation. It is experimentally
clarified that the high-frequency excitation changes the nonlinear property of the bifurcation from supercritical pitchfork
bifurcation to subcritical pitchfork bifurcation and then the stable steady state of the beam exhibits hysteresis as the compressive
force is reversed.
This work was partially supported by the Japanese Ministry of Education, Culture, Sports, Science, and Technology, under Grants-in-Aid
for Scientific Research 16560377. 相似文献
56.
Prof. Hiroshi Watanabe Ming-Long Yao Atsuko Yamagishi Kunihiro Osaki Toshiyuki Shitata Hirokazu Niwa Yotaro Morishima 《Rheologica Acta》1996,35(5):433-445
Linear and nonlinear viscoelastic properties were examined for a 50 wt% suspension of spherical silica particles (with radius of 40 nm) in a viscous medium, 2.27/1 (wt/wt) ethylene glycol/glycerol mixture. The effective volume fraction of the particles evaluated from zero-shear viscosities of the suspension and medium was 0.53. At a quiescent state the particles had a liquid-like, isotropic spatial distribution in the medium. Dynamic moduli G* obtained for small oscillatory strain (in the linear viscoelastic regime) exhibited a relaxation process that reflected the equilibrium Brownian motion of those particles. In the stress relaxation experiments, the linear relaxation modulus G(t) was obtained for small step strain (0.2) while the nonlinear relaxation modulus G(t, ) characterizing strong stress damping behavior was obtained for large (>0.2). G(t, ) obeyed the time-strain separability at long time scales, and the damping function h() (–G(t, )/G(t)) was determined. Steady flow measurements revealed shear-thinning of the steady state viscosity () for small shear rates (< –1; = linear viscoelastic relaxation time) and shear-thickening for larger (>–1). Corresponding changes were observed also for the viscosity growth and decay functions on start up and cessation of flow, + (t, ) and – (t, ). In the shear-thinning regime, the and dependence of +(t,) and –(t,) as well as the dependence of () were well described by a BKZ-type constitutive equation using the G(t) and h() data. On the other hand, this equation completely failed in describing the behavior in the shear-thickening regime. These applicabilities of the BKZ equation were utilized to discuss the shearthinning and shear-thickening mechanisms in relation to shear effects on the structure (spatial distribution) and motion of the suspended particles.Dedicated to the memory of Prof. Dale S. Parson 相似文献
57.
Steady-progressive-wave solutions are sought to the nonlinear wave equation derived previously [J. Fluids Struct. 16 (2002) 597] for flexural motions of an elastic beam traveling in an air-filled tube along its center axis at a subsonic speed. Fluid-structure interactions are taken into account through aerodynamic loading on the lateral surface of the beam subjected to small but finite deflection but end effects and viscous effects are neglected. Linear dispersion characteristics are first examined by exploiting the small ratio of the induced mass to the mass of the beam per unit length. Centered around the traveling speed of the beam, there exists such a narrow range of propagation velocity that the linear steady propagation is prohibited. In this range, it is revealed that some interesting nonlinear solutions exist. The periodic wavetrain is found to exist as the exact solution. Asymptotic analysis is then made by applying the method of multiple scales and the stationary nonlinear Schrödinger equation is derived for a complex amplitude. A monochromatic solution to this equation corresponds to the exact periodic solution. Imposing undisturbed boundary conditions at infinity, it is revealed that the localized solution exists as a result of balance between the linear instability and the nonlinearity. This solution is checked by solving the nonlinear equation numerically. It is further revealed that the amplitude-modulated wavetrain exists not only in the range of the velocity mentioned above but also outside of it. 相似文献
58.
This paper describes a significant influence of a slight Coulomb damping on buckling, using a simple two rods system. Coulomb damping produces equilibrium regions around the well-known stable and unstable steady states under the pitchfork bifurcation which occurs in the case without Coulomb damping. Also, the stability of the states in the equilibrium regions is examined by using the phase portrait. As a consequence, due to the slight Coulomb damping, it is theoretically clarified that the states in the equilibrium regions are locally stable, even in the neighborhood of the unstable steady states under the pitchfork bifurcation in the case without Coulomb damping, i.e., even in the neighborhood of the unstable trivial steady states in the postbuckling and the unstable nontrivial steady states under the subcritical pitchfork bifurcation. Furthermore, the experimental results are in qualitative agreement with the theoretically predicted phenomena. 相似文献
59.
Turning characteristics of multi-axle vehicles 总被引:3,自引:0,他引:3
This paper presents a mathematical model for multi-axle vehicles operating on level ground. Considering possible factors related to turning motion such as vehicle configuration and tire slip velocities, equations of motion were constructed to predict steerability and driving efficiency of such vehicles. Turning radius, slip angle at the mass center, and each wheel velocity were obtained by numerically solving the equations with steering angles and average wheel velocity as numerical inputs. To elucidate the turning characteristics of multi-axle vehicles, the effect of fundamental parameters such as vehicle speed, steering angles and type of driving system were examined for a sample of multi-axle vehicles. Additionally, field tests using full-scale vehicles were carried out to evaluate the basic turning characteristics on level ground. 相似文献
60.
Makoto Watanabe Masanori Morita Makoto Sakurai Mioko Maeda 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6-7):1823-1826
Preparations of small-ring and short-chain condensed phosphates were made by dry and wet processes, respectively. The crystallization of tetra- hexa-, and octaphosphates from the phosphate solution was not easy, and metal salts of these oligophosphates were amorphous and unstable at normal temperature. Guanidine tetraphosphate and ammonium hexaphosphate were crystalline and stable at normal temperature. 相似文献