Free boundary viscous flows at micro and mesolevel during liquid composites moulding process

Numerical simulation aspects, related to low Reynolds number free boundary viscous flows at micro and mesolevel during the resin impregnation stage of the liquid composite moulding process (LCM), are presented in this article. A free boundary program (FBP), developed by the authors, is used to track the movement of the resin front accurately by accounting for the surface tension effects at the boundary. Issues related to the global and local mass conservation (GMC and LMC) are identified and discussed. Unsuitable conditions for LMC and consequently GMC are uncovered at low capillary numbers, and hence a strategy for the numerical simulation of such flows is suggested. FBP encompasses a set of subroutines that are linked to modules in ANSYS. FBP can capture the void formation dynamics based on the analysis developed. We present resin impregnation dynamics in two dimensions. Extension to three dimensions is a subject for further research. Several examples are shown and efficiency of different stabilization techniques are compared. Copyright © 2004 John Wiley & Sons, Ltd.     

The standard model on non-commutative space-time

We consider the standard model on a non-commutative space and expand the action in the non-commutativity parameter . No new particles are introduced; the structure group is . We derive the leading order action. At zeroth order the action coincides with the ordinary standard model. At leading order in we find new vertices which are absent in the standard model on commutative space-time. The most striking features are couplings between quarks, gluons and electroweak bosons and many new vertices in the charged and neutral currents. We find that parity is violated in non-commutative QCD. The Higgs mechanism can be applied. QED is not deformed in the minimal version of the NCSM to the order considered. Received: 29 November 2001 / Published online: 25 January 2002     

Mikronachweis der Salicylsäure als Silbersalicylat

Zusammenfassung Es wird eine Methode beschrieben, nach der die Salicylsäure über ihr Ammonsalz als Silbersalicylat in kleinsten Mengen nachgewiesen werden kann. Es bilden sich dabei monokline Prismen in Form von Rhomboiden, die durch die Kristallwinkel, die schiefe Auslöschung und deren Beziehung zum Kristallumriß als Silbersalicylat identifiziert werden können. Erfassungsgrenze: 0,4 Salicylsäure. Ferner wird das unter Umständen ebenfalls bei der Reaktion auftretende Silbersalz der Benzoesäure und seine Unterscheidung von Silbersalicylat auf optischem Wege besprochen. Die Reaktion gelingt auch mit Mikrosublimaten.

---

Summary A method is described whereby minimal amounts of salicylic acid can be detected as silver salicylate, viâ the ammonium salt. Monoclinic prisms of the form of rhomboids are produced, which may be identified as silver salicylate from the crystal angles, the oblique extinction, and the relationship of these to the crystal outline. The limit of the method is 0,4 salicylic acid. The optical method for distinguishing between silver salicylate and silver benzoate, which is also formed in certain circumstances in the course of the reaction, is discussed. The reaction may be successfully applied to micro-sublimates.

---

Résumé On décrit une méthode, qui permet de déceler des plus petites quantités de l'acide salicylique comme salicylate d'argent en préparant d'abord le salicylate d'ammonium. Des prismes monoclines, en forme rhombique, se forment d'abord, qui peuvent être identifiés comme salicylate d'argent par l'angle du cristal (Kristallwinkel), l'extinction oblique (schiefe Auslöschung) et les relations de ceux aux contoures du cristal (Kristallumriß). Limite d'identification: 0,4 d'acide salicylique. Ensuite on discute aussi la différence entre le salicylate d'argent et le benzoate d'argent, qui se forme parfois au cours de la réaction, d'un mode optique. — La réaction peut être appliquée aussi à des micro-sublimés.

     

Asymmetric synthesis of [7]helicene-like molecules

[reaction: see text] A new approach to nonracemic [7]helicene-like molecules has been developed. Stereoselective Co(I)-mediated [2 + 2 + 2] cycloisomerization of aromatic triynes containing an asymmetric carbon atom produces [7]helicene-like scaffolds in diastereomeric ratios up to 100:0. This central-to-helical chirality transfer can be controlled by the absolute configuration at the asymmetric center and by the presence of carbon substituents.     

Studies on Radical Cations I. Molecular and electronic structure of [3]radialene cation produced by γ-irradiation in condensed phase

γ-Irradiation of tris (methylidene)-cyclopropane (‘[3]radialene’) 1 in a rigid electron scavenging matrix (butylchoride/i-pentane, 1:1) at 77 K leads to formation of its molecular cation 1 ⁺. Slight softening of the matrix by a temperature increase of 3–5 K results in formation of a newly absorbing species, tentatively assigned arising from structrral relaxation of 1 ⁺ by π-bond rotation:      

Electrophoretic analysis of oxidatively modified eye lens proteins in vitro: implications for diabetic cataract

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) profiles of eye lens proteins showed that both progression of diabetic cataract in rats in vivo and precipitation of soluble eye lens proteins stressed by free radicals in vitro were accompanied by significant protein cross-linking. There was a noticeable contribution of disulfide bridges to protein cross-linking in diabetic eye lens in vivo. In contrast, under conditions in vitro, when eye lens proteins were exposed to hydroxyl or peroxyl radicals, we showed that the participation of reducible disulfide linkages in the formation of high molecular mass products was markedly lower. These in vivo--in vitro differences indicate that the generally accepted role of reactive oxygen species in diabetic cataractogenesis may be overestimated in connection with the processes of protein cross-linking.     

The crystal structure of CuSb2O3Br: Slabs from cubic Sb2O3 interspersed between puckered hexagonal CuBr-type layers

The new compound CuSb₂O₃Br crystallize in the monoclinic space group Cc. The unit cell parameters are , , , β=90°, Z=16. The crystal structure is solved from single crystal data, R=0.0490. The compound show a layered structure with slabs from cubic Sb₂O₃ interspersed in between puckered layers of CuBr. The Sb(III) atoms have tetrahedral [SbO₃E] coordination where E is the 5s² lone pair, these units build up Sb₄O₄E₆ cages. The CuBr layers resemble those in hexagonal CuBr but the Cu(I) ions have actually tetrahedral [CuBr₃O] coordination. The Cu-O bonds link the Sb₄O₆ cages with the CuBr layers.     

Furan derivatives—III : Synthesis and properties of β-ketosulphides and sulphur derivatives of chalcones of 5-nitrofuran series

A series of 2-(5-nitro-2-furyl)-2-oxoethylarylsulphides 3a–3h has been prepared by the reaction of 5-nitro-2-furylbromomethylketone 1 with 4-substituted thiophenols 2a–2h. The determined rates of carbanion formation (log k'), pK values as well as ¹H NMR data show that in these compounds transmission of polar effects by the substituents through the -S- group occurs. Compounds 3a–3h react with aromatic aldehydes affording sulphur chalcone derivativěs of the 5-nitrofuran series 4a–4h. ¹H NMR, IR and UV spectra of prepared compounds are discussed.