An experimental study on effects of solid concentration and ζ-potential on pseudoplastic flow of suspensions

The pseudoplastic flow of suspensions, alumina or styrene-acrylamide copolymer particles in water or an aqueous solution of glycerin has been studied by the step-shear-rate method. The relation between the shear rate,<i>D</i>, and the shear stress,<i><img src="/content/l80322415l257t05/xxlarge964.gif" alt="tau" align="BASELINE" BORDER="0"></i>, in the step-shear-rate measurements, where the state of dispersion was considered to be constant, was expressed as<i><img src="/content/l80322415l257t05/xxlarge964.gif" alt="tau" align="BASELINE" BORDER="0"> = AD</i> <sup>1/2</sup> +<i>CD</i>. The effective solid volume fraction,<i>ø</i> <sub>F</sub>, and<i>A</i> were dependent on the shear rate and expressed by<i>ø</i> <sub>F</sub> =<i>aD</i> <sup>b</sup> and<i>A = <img src="/content/l80322415l257t05/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">D</i> <sup><img src="/content/l80322415l257t05/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0"></sup>. Combining the above relations, the steady flow curve was expressed by<i><img src="/content/l80322415l257t05/xxlarge964.gif" alt="tau" align="BASELINE" BORDER="0"> = <img src="/content/l80322415l257t05/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">D</i> <sup>1/2 + <img src="/content/l80322415l257t05/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0"></sup> +<i><img src="/content/l80322415l257t05/xxlarge951.gif" alt="eegr" align="MIDDLE" BORDER="0"></i> <sub>0</sub> (<i>1 – a D</i> <sup>b</sup>/0.74)<sup>–1.85</sup> <i>D</i>, where<i><img src="/content/l80322415l257t05/xxlarge951.gif" alt="eegr" align="MIDDLE" BORDER="0"></i> <sub>0</sub> is the viscosity of the medium.With an increase in solid volume fraction and a decreases in the absolute value of the<i><img src="/content/l80322415l257t05/xxlarge950.gif" alt="zeta" align="MIDDLE" BORDER="0"></i>-potential, the flow behavior of the suspensions changed from Newtonian (<i><img src="/content/l80322415l257t05/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0"> = <img src="/content/l80322415l257t05/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0"> = b</i> = 0), slightly pseudoplastic (<i><img src="/content/l80322415l257t05/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0"> = b</i> = 0), pseudoplastic (<i><img src="/content/l80322415l257t05/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0"></i> = 0) to a Bingham-like behavior.The change in viscosity of the medium had an effect on the change in the effective volume fraction.     

Thermoelastoplastic axisymmetric stress-strain state of laminated orthotropic shells

A method is proposed for the numerical analysis of the thermoelastoplastic stress-strain state of laminated shells of revolution, made of isotropic and orthotropic materials, under axisymmetric loading. The method is based on the Kirchhoff-Love hypotheses for a layer stack, the theory of deformation along paths of small curvature for isotropic materials, and Hill<img src="/content/l275t645jvk01618/xxlarge8217.gif" alt="rsquo" align="BASELINE" BORDER="0">s theory of flow with isotropic hardening for orthotropic materials. The problem is solved by the method of successive approximations. A numerical example is given.__________Translated from Prikladnaya Mekhanika, Vol. 40, No. 12, pp. 84–91, December 2004.     

关于n维单形的两个轨迹定理

在n维欧氏空间En中,应用向量方法,给出了关于n维单形的两个优美的轨迹定理.     

利用有限向量空间的子空间构作二元(s,l)叠加码

一个二元叠加码(s,l)-码在许多领域有着极为广泛的应用.利用有限域F_q上的向量空间的子空间构作了矩阵M_q(m,d,k),并证明了它是一个(s,l)一码,计算了(s,l)-码的参数.     

C~l -G_V TRIVIALITY OF FUNCTION GERMS AND NEWTON POLYHEDRA

We provide estimates on the degree of C l GV determinacy ( G is one of Mather’s groups R or K ) of function germs which are defined on analytic variety V and satisfies a non-degeneracy condition with respect to some Newton polyhedron. The result gives an explicit order such that the C l geometrical structure of a function germ is preserved after higher order perturbations, which generalizes the result on C l G triviality of function germs given by M.A.S.Ruas.     

Synthesis and biomimetic mineralization of l‐proline substituted polyphosphazenes as bulk and nanofiber

This work presents the synthesis of polyphosphazenes bearing L ‐proline methyl ester (ProOMe) and 4‐hydroxy‐l ‐proline methyl ester (HypOMe), aiming for new bioactive polymers for bone repair. The polymers were characterized by <sup>1</sup>H and <sup>31</sup>P NMR, FTIR, DSC, and TGA. Electrospun fibers were prepared using poly[bis(l ‐proline methyl ester)phosphazene] (PProP), and their potential for biomimetic mineralization, as well as the bulk material, were tested in simulated body fluid (1×SBF). Samples were analyzed between 24 h and 3 weeks of incubation using SEM/EDS and FTIR. After 24 h, spherical and flower‐like shapes of calcium phosphates (CaP) were crystallized on the bulk samples. The nanofibers presented spherical CaP crystals attached to them after 48 h of incubation. The Ca/P molar ratio of the crystals varied from 1.5 to 1.6. According to this study, PProP presents bioactivity <i>in vitro</i>, and its fibers offer sites for CaP nucleation like the collagen fibers in bone. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1318–1327