Elimination of non-uniform, extra-device flow effects in membrane adsorbers

Commercial use of membrane adsorbers in the biotechnology industry is increasing. Here the system time lag created by membrane adsorber peripherals and the membrane adsorber flow distribution headers has been modeled using an anion exchange membrane and bovine serum albumin (BSA). The system time lag was modeled as a zero order and first order time lag. The zero and first order time lags have been removed from the breakthrough curve. The method used does not involve fitting a mathematical expression to the breakthrough curve. Further no assumptions are made regarding the shape of the breakthrough curve in the absence of the time lag. The method has been used to calculate the Langmuir isotherm parameters.The membrane capacity was found to be twice as large as the capacity determined after removal of the time lag. The Langmuir constant was five times as large for the system without accounting for the time lag. Errors in fitting isotherm parameters can significantly impact frontal analysis and membrane adsorber scale-up. The Langmuir isotherm calculated under dynamic conditions with the system time lag removed, was in agreement with the static adsorption isotherm.     

Mathematical Relationships Between Bond-Bending Force Fields

Molecular mechanics softwares adopt various set of force field functions. In some cases, reliable data from one set of force field parameters cannot be used in a software that adopts another set of force field. Using mathematical approach, exact relationships between parameters from three bond-bending force fields, namely the (i) harmonic cosine angle, (ii) polynomial series, and (iii) Fourier series, are herein developed. Parameters from these three potential functions are further related to the approximate form, the harmonic angle function, which is valid for small change in chemical bond angle.     

Analogue of Aharonov-Bohm effect in spin gauge theory

We predict the possibility of observing analogue of the Aharonov-Bohm effect due to long range interaction between spins originating in the framework of spin gauge theory developed earlier. The effect is predicted for both electrons (fermions) and photons. Appropriate experimental set-ups are suggested.     

Dirac particle in a plane wave field and the semi‐classical approximation

In this paper we investigate the influence of photon represented by plane wave field on Dirac particle in the context of path integral approach given by Fradkin and Gitman formalism. In our case, although the action relative to Dirac particle in plane wave field seems to be non quadratic, the result obtained by semi‐classical approach is the same as that found by an exact calculation. Hence; when we add the plane wave field to any quadratic actions related to Fradkin and Gitman approach, the total action behaves like quadratic.     

关于拟Einstein场方程

In this paper some properties of a symmetric tensor field T(X, Y) = g(A(X), Y) on a Riemannian manifold (M,g) without boundary which satisfies the quasi-Einstein equation Rij-S/2gij=Tij+bξiξj are given. The necessary and sufficient conditions for this tensor to satisfy the quasi-Einstein equation are also obtained.     

Large Deviation Approach to the Randomly Forced Navier--Stokes Equation

The random forced Navier--Stokes equation can be obtained as a variational problem of a proper action. By virtue of incompressibility, the integration over transverse components of the fields allows to cast the action in the form of a large deviation functional. Since the hydrodynamic operator is nonlinear, the functional integral yielding the statistics of fluctuations can be practically computed by linearizing around a physical solution of the hydrodynamic equation. We show that this procedure yields the dimensional scaling predicted by K41 theory at the lowest perturbative order, where the perturbation parameter is the inverse Reynolds number. Moreover, an explicit expression of the prefactor of the scaling law is obtained.     

Rheology and microstructures formation of immiscible model polymer blends under steady state and transient flows

Viscoelastic properties of model immiscible blend were studied here under steady state condition at different initial conditions and transient flow conditions. The flow‐induced microstructure has been studied on these model blends. For this system, the elastic properties of the blend are mainly governed by the interface. Measurement of the dynamic modulus and of the first normal stress difference, both reflecting this enhanced elasticity, have been used to prove the blend morphology. The dynamic moduli after cessation of shear flow, the mean diameter of the disperse phase as generated by the shear flow, have been calculated using the model of Palierne. A procedure based on a direct fitting of the dynamic moduli with the model is compared with the one that uses a weight relaxation spectrum. On the other hand, the steady state normal stress data have been related to the morphology of the blend by means of Doi and Ohta model. The specific interfacial area is found to be inversely proportional to the ratio of interfacial tension over shear stress for the blend. The flow behavior during transient shear flow was also discussed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3519–3533, 2005