Wang Xian-Ju

Stability of TiO2 and Al2O3 Nanofluids

Aiming at the dispersion stability of nanofluids, we investigate the absorbency and the zeta potential of TiO2 and Al2O3 nanofluids under different pH values and different dispersant concentrations. The results show that in the mass fraction 0.05% alumina and 0.01% titanium dioxide nanosuspensions, the absolute value of the zeta potential and the absorbency of the two nanofluids with sodium dodecyl sulfate (SDS) dispersant are the highest at an optimal pH (pHAl2O3 ≈ 6.0, pHTiO2 ≈ 9.5) and that there is a good correlation between absorbency and zeta potential: the higher the absolute value of the zeta potential is, the greater the absorbency is, and the better the stability of the system is. The optimizing concentrations for SDS are 0.10% and 0.14%, respectively, at which the two nanofluids have the best dispersion results. The calculated DLVO interparticle interaction potentials verify the experimental results of the pH effect on the stability behavior.

A Microscopic Mechanism for Muscle Motion

We study the stochastic inclined rod model in a system with different complex potentials and discuss the effect of the spring on the system. The results of the calculation show that the spring, the effective radius of the G-actin and the intermolecular potential play key roles in the motion. The sliding speed is about 4.7×10-6m/s calculated from the model which well agrees with the experimental data.

Noise in Genotype Selection Model

We study the steady state properties of a genotype selection model in presence of correlated Gaussian white noise. The effect of the noise on the genotype selection model is discussed. It is found that correlated noise can break the balance of gene selection and induce the phase transition which can makes us select one type gene haploid from a gene group.

Muscle's Motion in an Overdamped Regime*

Based on the stochastic inclined rods model proposed by H. Matsuura et al., we study the motion of actin myosin system in an overdamped regime. Our model is composed of an inclined spring (rod), a myosin head and a myosin filament. The results of calculation show that the model can convert the random motion to one-directional motion, and the myosin head works as a resonator of random noise, which absorbs the energy through a stochastic resonance. The results show that the inclined rod and the intermolecular potential are very important for the system to move.

Fluctuation of Parameters in Tumor Cell Growth Model

We study the steady state properties of a logistic growth model in the presence of Gaussian white noise. Based on the corresponding Fokker-Planck equation the steady state solution of the probability distribution function and its extrema have been investigated. It is found that the fluctuation of the tumor birth rate reduces the population of the cells while the fluctuation of predation rate can prevent the population of tumor cells from going into extinction. Noise in the system can induce the phase transition.

Energy of Gravitational Field of Static Spherically Symmetric Neutron Stars

By using the Einstein–Tolman expression of the energy-momentum pseudo-tensor, the energy density of the gravitational field of the static spherically symmetric neutron stars is calculated in the Cartesian coordinate system. It is exciting that the energy density of gravitational field is positive and rational. The numerical results of the energy density of gravitational field of neutron stars are calculated. For neutron stars with , the ratio of the energy density of gravitational field to the energy density of pure matters would be up to 0.54 at the surface.

Correlated Noise Effects on Gene Expression

Based on the model describing the regulation of the PRM operator region of λ phage proposed by Hasty et al. [Proc. Nat. Acad. Sci. 97 (2000) 2075], we study the steady-state probability distribution properties of the model in the presence of correlated Gaussian white noise. We find that the degree of correlation of the noises can affect the form of the steady-state probability distribution. When the degree of correlation of the noises increases, the form of the steady-state probability distribution changes from a bimodal into a unimodal structure. The steady-state probability distribution extrema have also been investigated. We find that noise correlation can change the positions of the extreme value of the steady-state probability distribution of the model greatly.

Properties of Rotating Neutron Stars in the Relativistic σ-ω Model

The properties such as the moment of inertia, the surface redshift and the radius of gyration of rotating neutron stars in the relativistic σ-ω model are studied with the Hartles method. The relation between the angular velocity of the fluid relative to the local inertial frame and the uniform angular velocity relative to the infinite is calculated.

Thermal Dynamics Behavior of Protoneutron Star Matter

In the relativistic model, including the vacuum fluctuation of nucleons and σ mesons, the effect of the temperature to the composition and equation of state of protoneutron star matter, nucleon effective mass and chemical potential of neutrons and electrons are studied. We find that the influence of the temperature on the equation of state of protoneutron star matter is indeed small, however, its influence on the composition of protoneutron star, which will contribute to the evolution of protoneutron star, cannot be neglected in low density region. The chemical potentials of neutrons and electrons also depend on the temperature in almost the same density region.

A General Random Walk Model of Molecular Motor

A general random walk model framework is presented which can be used to statistically describe the internal dynamics and external mechanical movement of molecular motors along filament track. The motion of molecular motor in a periodic potential and a constant force is considered. We show that the molecular motors movement becomes slower with the potential barrier increasing, but if the force is increased, the molecular motors movement becomes faster. The relation between the effective rate constant and the potential barriers height, and that between the effective rate constant and the value of the force are discussed. Our results are consistent with the experiments and relevant theoretical consideration, and can be used to explain some physiological phenomena.