ADSORPTION DYNAMICS OF MACROPOROUS POLYMERIC ADSORBENT I.The Studies on the Particle Diffusion Mass-Transfer Process

The adsorption dynamics for phenol in aqueous solution of the adsorbent based on polystyrene was studied. In order to distinguish with the Boyd quasi-homogeneous model of the inner structure of ion-exchanger, the particle diffusion model including surface diffusion model and pore diffusion model was suggested which is suitable to the macroporous adsorbent. The diffusiondetermination step of the adsorption process was established and the effective diffusion coefficient was also determined. The influence of surface diffusion and pore diffusion on the particle diffusion rate was investigated qualitatively. All of these were very important to improve the structure of the macroporous adsorbent in order to improve the mass-transfer rate.

Transport in Astrophysics: III. Diffusion from the Galactic Plane

New solutions, for the stationary and temporary states, are derived for the 1D diffusion of cosmic rays in the presence of losses. The new results are applied to the latitude profile of radiation emitted above the galactic plane. Percolation theory for a spiral galaxy coupled with the evolution of the super-bubbles allows building a model for the radiation of a spiral galaxy as seen face on. The annulus of radiation of our galaxy is also simulated and the excess of radiation observed at the centre of our galaxy is explained by the sine law which arises in the theory of the image.

Efficient Sequestration of Congo Red Dye from Aqueous Solutions Using Pamam Dendrimer-Silica Composite

This study investigates the removal of Congo Red dye from aqueous solution using functionalized generation 3.0 and 5.0 polyamidoamine dendrimer-silica gel composite (G-3PS, G-5PS). Fourier Transform-Infra Red spectroscopy, Brunauer Emmett and Teller, Thermo Gravimetric Analysis, pH at point of zero charge, and scanning electron microscopy measurements have been applied to characterize the synthetic nanohybrid composite, these techniques revealed the successful functionalization of both dendrimer molecules and subsequent immobilization onto silica gel. The implications of varying adsorption parameters such as contact time, initial concentration of adsorbate, temperature and pH on both composites were studied. Experimental data obtained from batch adsorption processes were fitted into two equilibrium isotherms (Langmuir and Freundlich) and 3 kinetic models (Pseudo-First-Order, Pseudo-Second-Order, Intra Particle Diffusion). Adsorption mechanism was mainly governed by film diffusion due to electrostatic interactions between the functionalized dendrimer surface and Congo Red molecules. Thermodynamic parameters illustrate that the adsorption is endothermic and spontaneous. Findings suggest the Nanocomposites (G-3PS and G-5PS) are good adsorbents for the removal of Congo Red dye from aqueous solutions.

Transport in Astrophysics: VI. Ultra-High Energy Cosmic Rays

Two new solutions of the homogeneous diffusion equation in 1D are derived in the presence of losses and a trigonometric profile for a profile of density. A simulation for the ankle in the energy distribution of cosmic rays (CRs) is provided in the framework of the fine tuning of the involved parameters. A theoretical image for the overall diffusion of CRs in galactic coordinates is provided.

Transport in Astrophysics: I. Diffusion of Solar and Galactic Cosmic Rays

Some solutions for the diffusion phenomenon as a function of time and space are reviewed. Two new solutions of the homogeneous diffusion equation in 1D and 2D are derived in the presence of an existing fixed number of particles. The initial conditions which allow deriving a power law behavior for the energy of the cosmic rays (CR) are derived. The superposition of transient diffusive phenomena on an existing power law distribution for the energy of CR allows simulating the knee, the second knee, and the ankle.

Transport in Astrophysics: II. Diffusion with Advection in Expanding Nebulae

The structure across an expanding shell in which drift and diffusion redistribute material requires careful consideration in order to correlate the surface brightness with the physical parameters. A new solution in terms of Fourier series is suggested for 1D diffusion in the presence of a drift velocity. The astrophysical parameters are chosen in agreement with the astronomical data for the planetary nebula A39. The new solution is then inserted into the existing theory for the astrophysical image which allows dealing with the intensity of radiation emitted in a spherical layer.

STUDY ON DIFFUSION WELDING OF ALUMINIUN MATRIX COMPOSITE

Effects of diffusion welding parameters on strength of welded joint based on particle reinforced alumini- um matrix composite Al2O3p/6061Al were studied by comparing with aluminium matrix alloy,Mecha- nism for the loss of joint strength was analyzed.It was pointed out that the key processing parameters affecting the strength of joint was the welding temperature.The high quality joint can be successfully obtained with appropriate diffusion welding parameters.

Analysis Scheme for Density Modulation Experiments to Study Particle Confinements

Density modulation experiments are powerful experimental schemes for the study of particle transport. The diffusion coefficients （D） and convection velocity （V）, which cannot be evaluated from the particle balance in the equilibrium state, can be obtained separately. Further, the estimated values of D and V are determined independent of the absolute value of the particle source rate, which is difficult to obtain experimentally. However, the sensitivities and interpretation of D and V from the modulation experiments need to be considered. This paper describes numerical techniques for solving the particle balance equation of the modulation components. Examples of the analysis are shown regarding the data of LHD experiments, and the results of the modulation experiments are discussed.

Transport in Astrophysics: IV. Anomalous Redshift in the Solar System

The anomalous redshift on the sun’s limb and that measured by Pioneer-6 are interesting for the process of absorption of light and the spatial density of matter around the sun. Here we derive a 3D solution for the diffusion equation in the case of the steady state, which is then adopted as the density of the ionized matter around the sun. In order to deal with the observed light’s intensity, two integrals along the line of sight are evaluated. Alternatives to the Doppler shift have been considered as mechanisms: a thermal model, a plasma effect, the interaction of a low density electromagnetic wave with an electron and the interaction of light with a low density Fermi gas in standard QED. These four models are compared in the case of the Pioneer-6 signal.

Evaluation of SrBr2 Hydration Reaction Rate with Repeated Cycling

In this study, we evaluated the SrBr2 hydration reaction rate on repeated cycling. It was estimated that hydrated SrBr2 particles were expanded by hydration and condensed to form secondary particles;thus, the hydration reaction was reduced by repeated cycles. Using volumetric methods, we examined the effect of repetition on the reaction rate for 900 cycles during hydration and dehydration and analyzed the reaction rate using the unreacted core-shell model. From the experimental and calculated results, we confirmed that reaction rate decreased and the sample particles formed secondary particles after 900 repeated cycles. By analyzing the unreacted core-shell model, we found that the coefficient of H2O diffusion in the particles exponentially decreased with increasing repeated cycles. The value of the diffusion coefficient after 900 cycles was five times lower than that of the first cycle. To achieve stable repeated hydration cycles, technology to control the formation of secondary particles must be investigated.

Extension of the low diffusion particle method for near-continuum two-phase flow simulations

The low diffusion （LD） particle method, proposed by Burt and Boyd, is modified for the near-continuum two-phase flow simulations. The LD method has the advantages of easily coupling with the direct simulation Monte Carlo （DSMC） method for multi-scale flow simulations and dramatically reducing the numerical diffusion error and statistical scatter of the equilibrium particle methods. Liquidor solid-phase particles are introduced in the LD method. Their velocity and temperature updating are respectively, calculated from the motion equation and the temperature equation according to the local gas properties. Coupling effects from condensed phase to gas phase are modeled as momentum and energy sources, which are respectively, equal to the negative values of the total momentum and energy increase in liquid or solid phase. The modified method is compared with theoretical results for unsteady flows, and good agreements are obtained to indicate the reliability of the one-way gas-to-particle coupling models. Hybrid LD-DSMC algorithm is implemented and performed for nozzle discharging gas-liquid flow to show the prospect of the LD-DSMC scheme for multi-scale two-phase flow simulations.

Remarkable Findings in Fundamental Theory of Quantum Mechanics—Matter Wave and Discrete Time in Physics

The relation of matter wave, which is well-known as a hypothesis proposed by de Broglie in 1923, gave basis for establishing the quantum mechanics. After that, experimental results revealed that a micro particle has a wave nature. However, the theoretical validity of the relation itself has never been revealed since his proposal. Theoretical basis that a micro particle has a wave nature has been thus disregarded in the unsolved state. The diffusion equation having been accepted as Fick’s second law was derived from the theory of Markov process in mathematics. It was then revealed that the diffusivity D depends on an angular momentum of a micro particle in a local space. The fact being unable to discriminate between micro particles in a local space resulted in having to accept the existence of minimum time t0 (>0) in the quantum mechanics. Based on t0 and D obtained here, the theoretical validity of relation of matter wave was confirmed. Denying the density theorem in mathematics for time in physics indicates that the probabilistic interpretation is essentially indispensable for understanding the quantum mechanics. The logical necessity of quantum theory itself is thus understandable through introducing t0 into the Newton mechanics. It is remarkable that the value of t0 between 1.14×10-17 s ≤ t0 ≤1.76×10-14 s obtained here is extremely larger than that of the well-known Planck time tp=5.396×10-44 s.

Large Eddy Simulation of Particle-Laden Turbulent Flow over a Backward-Facing Step

Particle diffusion in large eddy structures with various Stokes number was analyzed numerically for the two-dimensional gas-particle turbulent flow over a backward-facing step. The continuous phase simulation was analyzed using the large eddy simulation (LES) method while the particle phase was analyzed by the Lagrangian method. The spatial and temporal results were used to analyze the evolution of the large eddy coherent structures and the vortex-particle interactions. The effect of the particle Stokes number on the in-stantaneous particle concentration distributions was also discussed. The simulations of the single-phase flow reproduced the character of the separation and reattachment flow and the essential features of the coherent structures. Numerous and complex vortex structures appeared at the high Reynolds number. Furthermore, the simulation shows that the Stokes number plays an important role in the particle dispersion and the instanta-neous particle distribution. The continuous phase time-averaged results and the particle phase time-averaged results obtained from the LES analysis agree well with previous experimental data.

Particle acceleration and transport in the inner heliosphere

In the solar system, our Sun is Nature's most efficient particle accelerator. In large solar flares and fast coronal mass ejections(CMEs), protons and heavy ions can be accelerated to over ~GeV/nucleon. Large flares and fast CMEs often occur together. However there are clues that different acceleration mechanisms exist in these two processes. In solar flares, particles are accelerated at magnetic reconnection sites and stochastic acceleration likely dominates. In comparison, at CME-driven shocks,diffusive shock acceleration dominates. Besides solar flares and CMEs, which are transient events, acceleration of particles has also been observed in other places in the solar system, including the solar wind termination shock, planetary bow shocks, and shocks bounding the Corotation Interaction Regions(CIRs). Understanding how particles are accelerated in these places has been a central topic of space physics. However, because observations of energetic particles are often made at spacecraft near the Earth,propagation of energetic particles in the solar wind smears out many distinct features of the acceleration process. The propagation of a charged particle in the solar wind closely relates to the turbulent electric field and magnetic field of the solar wind through particle-wave interaction. A correct interpretation of the observations therefore requires a thorough understanding of the solar wind turbulence. Conversely, one can deduce properties of the solar wind turbulence from energetic particle observations. In this article I briefly review some of the current state of knowledge of particle acceleration and transport in the inner heliosphere and discuss a few topics which may bear the key features to further understand the problem of particle acceleration and transport.

Parameter Estimation of S-Shaped Growth Model:A Modified Particle Swarm Algorithm

Parameter estimation plays a critical role for the application and development of S-shaped growth model in the agricultural sciences and others.In this paper,a modified particle swarm optimization algorithm based on the diffusion phenomenon（DPPSO） was employed to estimate the parameters for this model.Under the sense of least squares,the parameter estimation problem of S-shaped growth model,taking the Gompertz and Logistic models for example,is transformed into a multi-dimensional function optimization problem.The results show that the DPPSO algorithm can effectively estimate the parameters of the S-shaped growth model.

Field study of a soft X-ray aerosol neutralizer combined with electrostatic classifiers for nanoparticle size distribution measurements

Most conventional aerosol neutralizers are based on radioactive sources, which are controlled by strict regulations restricting their handling, transport, and storage. The TSI 3087 soft X-ray （SXR） neutralizer circumvents these legal restrictions. The aim of the present work is to compare the performance of a standalone SXR aerosol neutralizer with that of conventional radioactive aerosol neutralizers based on 85Kr （TSI 3077） and 241Am （Grimm 5522） by performing field tests in a real environmental scenario. The results obtained when the SXR neutralizer was connected to a mobility particle sizer spectrometer （MPS）, different from the device suggested by the manufacturer, were comparable with those obtained with the use of radioactive aerosol neutralizers. In changing the neutralizer, the particle number concentrations, measured with the MPS connected to the SXR neutralizer, almost remained within the 10% uncertainty bounds for the particle size interval 10-300 nm, when diffusion losses inside the SXR tube were considered. Based on our comparisons, the SXR neutralizer can be regarded as a standalone instrument that could solve the problems associated with legal restrictions on radioactive neutralizers and fulfil the need for a portable instrument for different field test purposes.