Nonlinear Taylor stability of viscoelastic fluids

Using Stuart's energy method, the torque on the inner cylinder, for a second order fluid, in the supercritical regime is calculated. It is found that when the second normal stress difference is negative, the flow is more stable than for a Newtonian fluid and the torque is reduced. If the second normal stress difference is positive, then the flow is more stable and there is no torque reduction. Experimental data related to the present work are discussed.Nomenclature a amplitude of the fundamentals - A _ij ⁽¹⁾ , A _ij ⁽²⁾ first and second Rivlin-Ericksen tensors - d r ₂–r ₁ - D d/dx - E - F - g _ij metric tensor - G torque on the inner cylinder in the supercritical regime - h height of the cylinders - k ₀ /d ² - k ₁ /d ² - I ₁ - I ₂ - I ₃ - I ₄ - r ₁, r ₂ radii of inner and outer cylinders respectively - r ₀ 1/2(r ₁+r ₂) - R Reynolds number ₁ r ₁ d/ ₀ - R _c critical Reynolds number - T Taylor number r _{1 1} ² d ^{3 2}/ ₀ ² *) - T _c critical Taylor number - u ₁, v ₁, w ₁ Fundamentals of the disturbance - u _i , v _i , w _i , (i>1) harmonics - mean velocity (not laminar velocity) - u –u ₁/ar _{1 1} - v v ₁/Rar _{1 1} - x (r–r ₀)/d - , material constants - 0 viscosity - wave number d - density - ₁ angular velocity of inner cylinder - tilde denotes complex conjugate     

Rubesanolides A and B: diterpenoids from Isodon rubescens

From the medicinal plant Isodon rubescens, we isolated two novel diterpenes, rubesanolides A (1) and B (2). The compounds contain a unique β-lactone subgroup. This is the first discovery for a natural diterpene having rings A, B, and C in chair, boat, and twist-chair conformations, respectively. The structures were elucidated by analysis of spectroscopic data, and the absolute configuration of 1 was determined by X-ray diffraction.     

A natural product-like inhibitor of NEDD8-activating enzyme

The natural product-like 6,6″-biapigenin has been identified as only the second inhibitor of NEDD8-activating enzyme using virtual screening. This compound was active in enzyme and cell-based assays, with potency in the micromolar range.     

Preparation of unsymmetrical distyryl BODIPY derivatives and effects of the styryl substituents on their in vitro photodynamic properties

A series of unsymmetrical distyryl BODIPYs have been prepared which function as highly potent photosensitisers with in vitro IC(50) values as low as 15 nM. Their cellular uptake, subcellular localisation and photocytotoxicity depend greatly on the styryl substituents.     

Studies on calcium alginate stanch fibre by radiation sterilization and its biology

This paper explored the technical feasibility of surgical calcium alginate stanch fibre steriliged by radiation. By detecting the biological load before and after irridiation the optimum sterilized dose is 10–12KGY. By determing the Ca⁺⁺ content, a linear regression equation relative to adsorbed dose and Ca⁺⁺ content percentage is given out. lgD=0.13449+7.966x10^-3N(r=0.9935) The result of biological studies of radio sterilized stanch fibre to be applied on adult rabbits and NIH mice by biologic test was performed that the γ-ray sterilized stanchfibre had no irritant effect on both the health and the wound skin, crust formation rate was better than of the check. The total and partial irritation intensity and the allergization rate became zero.     

Poly(p‐phenylenevinylene) presenting pendent pentaphenylene dendron groups for light‐emitting diodes

We have synthesized, using the Gilch method, a novel poly(p‐phenylenevinylene) derivative (PPV‐PP) containing two pendent pentaphenylene dendritic wedges, and have characterized its structure and properties. The incorporated side chain pentaphenylene dendrons serve as solubilizing groups, prevent π‐stacking interactions from occurring between the polymer main chains, and suppress the formation of excimers in the solid state. Photoluminescence studies indicate that efficient intramolecular energy transfer occurred from the photoexcited pentaphenylene groups to the poly(p‐phenylenevinylene) backbone. The polymer film exhibits a maximum emission at 510 nm and had a photoluminescence efficiency of 46%, which is similar to that measured in dilute solution. The photoluminescence spectra remained almost unchanged after thermal annealing at 150 °C for 20 h, and displayed inhibited excimer formation. Polymer light‐emitting diodes that we fabricated in the configuration ITO/PEDOT/PPV‐PP/Mg:Ag/Ag exhibited a maximum emission peak at 513 nm, corresponding to the green region [x = 0.30 and y = 0.62 in the Commission Internationale de L'Eclairage (CIE) chromaticity coordinates]. The maximum brightness and maximum luminance efficiency were 1562 cd/m² and 1.93 cd/A, respectively. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5147–5155, 2005     

海洋蔓足类与宿主动物的共栖关系

蔓足类的宿主动物极为广泛，自海绵动物至脊椎动物皆有代表.生活方式有无机固着生活、兼性共栖和专主共栖3种生态类群，以共栖种类占绝对优势(48.2%).蔓足类在宿主体上的定着位置与其利用水流的方式有关，其形态结构、个体大小与宿主的生物学和习性有关.蔓足类与宿主的共栖还与系统发育有关，较古老的种类主要附着在岩石或其它无机物上，与宿主共栖的种，对宿主无明显选择性;较近代的种，对宿主则有明显选择性.     

On Minimal Generating Sets of E(D n ), A(D n) and I(D n ) with Even n

Let Dn be the dihedral group of order 2n. Denote by E(Dn) (resp. A(Dn), I(Dn)) the distributively generated nearring generated by the set of all endomorphisms (resp. automorphisms, inner automorphisms). In this paper, we determine for each one of the above three nearrings a minimal (additive) generating set. For E(Dn), this set contains the identity mapping and four other endomorphisms; for A(Dn), the identity mapping, one outer automorphism and one inner automorphisms; and for I(Dn), the identity mapping and two inner automorphisms.     

A decomposition theorem on the scalar potential of a compressible BKZ fluid

Based on the existence of a caloric equation of state in the thermodynamic theory of a nonlinear viscoelastic fluid (Bernstein, Kearsley and Zapas, 1964), and the additional assumption that the local entropy production along any instantaneous deformation path is finite, we first show that such a fluid behaves as a perfectly elastic material whenever the deformation gradient suffers from a jump-type discontinuity. The nature of the apparently perfectly elastic material serving to interpret results in the instantaneous deformation depends on the previous historyonly through two parameters, namely, the density and the temperature of the fluid immediately prior to the jump. This result is then applied, in conjunction with the usual conditions of isotropy and objectivity as well as an application of Schur's Lemma on irreducible sets of matrices, to obtain a decomposition of the scalar potential of the compressible Bernstein-Kearsley-Zapas Fluid (abbrev. BKZ Fluid).

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Zusammenfassung Gegründet auf der Existenz einer kalorischen Zustandsgleichung in der thermodynamischen Theorie einer nichtlinearen viskoelastischen Flüssigkeit (Bernstein, Kearsley und Zapas, 1964) und der zusätzlichen Annahme, daß die örtliche Entropiezunahme entlang einer Deformationskurve endlich ist, zeigen wir zuerst, dass sich eine solche Flüssigkeit wie ein ideales elastisches Material verhält, wenn der Deformationsgradient eine sprunghafte Unstetigkeit aufweist. Die Eigenschaften des scheinbar idealen elastischen Materials, die dazu dienen, Ergebnisse der momentanen Deformation zu interpretieren, hängen von der Vorbehandlung nur durch Werte von zwei Parametern ab, nämlich der Dichte und Temperatur der Flüssigkeit direkt von der sprunghaften Veränderung. Das Ergebnis, zusammen mit den üblichen Bedingungen der Isotropie und Objektivität wie auch der Anwendung von Schurs Lemmas über nichtreduzierbare Gruppen von Matrizen, wird dann dazu verwendet, eine Zerlegung des skalaren Potentials einer verdichtbaren Bernstein-Kearsley-Zapas-Flüssigkeit (BKZ-Flüssigkeit) zu erzielen.