Summary: In the present work, various surface modifications have been applied to titanium surface. The aim of the modifications was to improve cell adhesion and to determine their influence on the properties of titani...
详细信息
Summary: In the present work, various surface modifications have been applied to titanium surface. The aim of the modifications was to improve cell adhesion and to determine their influence on the properties of titanium surface. The unmodified and modified surfaces were observed using SEM. Subtle changes in modified surface layer of titanium samples were examined using the Auger Electron Microanalysis and Photoelectron Spectroscopy. The properties of surfaces were evaluated by contact angle and roughness measurements. The results revealed large differences in morphology of Ti modified with different procedures whereas only minor differences in the chemistry of the surfaces were detected. Preliminary quantitative measurements (cell number, viability and differentiation) of the MG 63 osteoblast-like cells in the direct contact with the surface of the investigated materials show that both the not pre-treated titanium surface and the surfaces modified by the methods used in the this work are all well tolerated by the living cells. Within the experimental scatter all the surfaces provided good substrate for proliferation and growth of the cells.
In this paper we evaluate the enhancement of nonequilibrium concentration fluctuations induced by the Soret effect when a binary fluid layer is subjected to a stationary temperature gradient. Starting from the fluctua...
详细信息
In this paper we evaluate the enhancement of nonequilibrium concentration fluctuations induced by the Soret effect when a binary fluid layer is subjected to a stationary temperature gradient. Starting from the fluctuating Boussinesq equations for a binary fluid in the large-Lewis-number approximation, we show how one can obtain an exact expression for the nonequilibrium structure factor in the long-wavelength limit for a fluid layer with realistic impermeable and no-slip boundary conditions. A numerical calculation of the wave-number dependence of the nonequilibrium enhancement and of the corresponding decay rate of the concentration fluctuations is also presented. Some physical consequences of our results are briefly discussed.
Effective attraction between like-charged walls mediated by counterions is studied using local molecular field (LMF) theory. Monte Carlo simulations of the “mimic system” given by LMF theory, with short-ranged “Cou...
详细信息
Effective attraction between like-charged walls mediated by counterions is studied using local molecular field (LMF) theory. Monte Carlo simulations of the “mimic system” given by LMF theory, with short-ranged “Coulomb core” interactions in an effective single particle potential incorporating a mean-field average of the long-ranged Coulomb interactions, provide a direct test of the theory, and are in excellent agreement with more complex simulations of the full Coulomb system by Moreira and Netz [Eur. Phys. J. E 8, 33 (2002)]. A simple, generally applicable criterion to determine the consistency parameter σmin needed for accurate use of the LMF theory is presented.
We develop a formalism for single molecule dynamic force spectroscopy to map the energy landscape of protein-protein complex (P1P2). The joint distribution P(τ1,τ2) of unbinding lifetimes τ1 and τ2, measurable in ...
详细信息
We develop a formalism for single molecule dynamic force spectroscopy to map the energy landscape of protein-protein complex (P1P2). The joint distribution P(τ1,τ2) of unbinding lifetimes τ1 and τ2, measurable in a compression-tension cycle, which accounts for the internal relaxation dynamics of the proteins under tension, shows that the histogram of τ1 is not Poissonian. The theory is applied to the forced unbinding of protein P1, modeled as a wormlike chain, from P1P2. We propose a new class of experiments which can resolve the effect of internal protein dynamics on the unbinding lifetimes.
We determine the persistence length lp for a bacterial group I ribozyme as a function of concentration of monovalent and divalent cations by fitting the distance distribution functions P(r) obtained from small angle x...
详细信息
We determine the persistence length lp for a bacterial group I ribozyme as a function of concentration of monovalent and divalent cations by fitting the distance distribution functions P(r) obtained from small angle x-ray scattering intensity data to the asymptotic form of the calculated PWLC(r) for a wormlike chain. The lp values change dramatically over a narrow range of Mg2+ concentration from ∼21 Å in the unfolded state (U) to ∼10 Å in the compact (IC) and native states. Variations in lp with increasing Na+ concentration are more gradual. In accord with the predictions of polyelectrolyte theory we find lp∝1/κ2 where κ is the inverse Debye-screening length.
The aim of this study was to develop the dynamic model of lower limb using static and dynamic reflex properties of flexion reflex. Identification of torque response associated with hip angle and angular velocity was t...
详细信息
ISBN:
(纸本)0974249211
The aim of this study was to develop the dynamic model of lower limb using static and dynamic reflex properties of flexion reflex. Identification of torque response associated with hip angle and angular velocity was tested in 6 subjects with chronic SCI. Each subject placed in a supine position and lower leg was fixed with the knee at 155°±12 and the ankle at 126°±14. The hip was aligned with the axis of the Biodex motor in order to impose hip movements to the leg. A train of 10 stimulus pulses (50mA, 1ms) as reference pulse were applied at 200Hz to the skin of the medial arch to trigger flexion reflex reflexes. From this experiment, we identified the torque response as linear function of hip angle and angular velocity. In order to simulate the lower limb of spinal cord injured patients for functional electrical stimulation, we developed two dimensional dynamic model with three segments, thigh, shank and foot. Influences of stimulation parameters such as amplitude, frequency and duration time of pulse train were investigated with Taguchi method to obtain best results.
By probing the resonances between a photonic band and an external laser field and their nonlinear changes in angle-resolved reflectivity, we show experimental evidence that the nonlinear optical changes in a two-dimen...
详细信息
By probing the resonances between a photonic band and an external laser field and their nonlinear changes in angle-resolved reflectivity, we show experimental evidence that the nonlinear optical changes in a two-dimensional photonic crystal waveguide with a Kerr nonlinearity are critically dependent on the dispersion nature and the group velocity of the photonic bands. The results agree well with the behavior predicted from band structures, indicating that the design of nonlinear optical properties of material systems is realistically possible by band dispersion and group velocity engineering.
暂无评论