Materials Literature
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Encouraged by theoretical predictions that nematic phases formed from V-shaped compounds could be biaxial, shape-persistent phenylene ethynylene arms linked by 1,3-phenylene, 4,4′-diphenylenemethane and 3,6-fluorenone units have been synthesised. Crystallisation and micro-segregation is prevented by 2,5-alkoxy substit…
For the first time, HF-EPR (94.5 GHz) spectroscopy has been used to determine crystal field parameters in chromium(III) coordination compounds. The large zero-field splitting parameters of the dark-green photochromic trans-RSSR-[CrCl(2)(cyclam)](2)ZnCl(4), 1, the red-purple trans-RSSR-[CrCl(2)(cyclam)]Cl, 2, and the r…
Treatment of octakis(octylthio)porphyrazine (H(2)OOSPz) with cis-bis(benzonitrile)dichloroplatinum(II) in a 1,2,4-trichlorobenzene (TCB)-n-BuOH mixture at 190 degree C affords the asymmetric porphyrazine 2H-heptakis(octylthio)porphyrazine, H(2)HOSPz, in ca. 40% yield. In the key synthetic step the two-electron reduced…
We describe a new method to isolate and concentrate transparent exopolymeric particles (TEP), either naturally occurring or produced by phytoplankton in cultures. The principles of this method are to use TEP‐sticking properties coupled with magnetic properties of paramagnetic microspheres to magnetically and selective…
Hydroxyapatite (HA) is widely used as a bioactive ceramics since it forms a chemical bonding to bone.The disadvantage of this material is its poor mechanical properties.HA can be degraded in body, which is the reason for its bioactivity, but too fast degradation rate could cause negative effects, such as macrophage pr…
En este trabajo se presentan los resultados de la caracterizacion del quitosano obtenido a partir de la modificacion quimica de la quitina. Se ha aplicado el metodo de viscosimetria capilar para determinar el peso molecular promedio viscoso, a partir de la ecuacion de Mark-Houwink; la tecnica de analisis fue validada…
In order to enhance the understanding of the redox equilibriums of uranyl ions in molten NaCl-2CsCl eutectic salt UV-Vis absorption spectrophotometry measurements were performed for UO2 2+ in molten NaCl-2CsCl at 923 K under simultaneous electrolytic control of their ratio. A prominent absorption band at 395 nm was as…
Sol-gel-derived P 2 O 5 SiO 2 glasses were investigated to prepare high proton conductors for fuel cell electrolyte. Glasses with a pore size of 2-30 nm diam were prepared using Si ( OC 2 H 5 ) 4 , colloidal silica, PO ( OCH 3 ) 3 , H 3 PO 4 , and POCl 3 , the pore properties of which were discussed to relate with t…
The conducting polypyyrole-montmorillonite clay (PPy/MMT) composites were prepared using 2: 1 mole ratio of FeCl3 / pyrrole with various percentages of MMT clay in aqueous medium. The prepared samples were subjected to structural, thermal and morphological characterizations and d.c. conductivity measurement. The condu…
Abstract The parameters that promote the formation of surface defects on multi‐phase polymer systems during injection molding are not yet clearly understood. The objective of this work is to establish the influence of composition, particularly the role of rubber, on the rheological properties of such multi‐phase syste…
Polyvinylalcohol, partially substituted with lipophilic acyl chains, generates polymeric micelles in aqueous phase, containing a hydrophobic core able to encapsulate lipophilic drugs. Two types of polymers were obtained by conjugation of polyvinylalcohol with oleoyl or linoleoyl chains as pendant groups. The polymers,…
C18H37OH–C20H41OH is an example of a binary system showing isopolymorphism. The two alkanols display the same polymorphic behaviour. At low temperatures, they crystallize into the same ordered form γ (C2/c, Z = 8). On heating, γ transforms into the rotationally disordered form R′IV (C2/m, Z = 4), at a few degrees belo…
Experiments were conducted to evaluate the superplastic properties in three orthogonal directions after processing by equal-channel angular pressing (ECAP). Using an Al-3% Mg-0.2% Sc alloy pressed to a strain of ∼8 through route BC, miniature tensile specimens were cut inthe pressing direction perpendicular to the tra…
A novel explosive welding technique which uses underwater shock waves to weld thin sheets and the technical advantages of this technique are reported. Using this technique, a thin metal plate is uniformly accelerated by underwater shock waves. The initial angle of inclination of the explosive pack is determinant in hi…
Abstract We studied the intricate pH‐ and light‐dependent network of the thermal and photochemical reactions of the 4′‐(dimethylamino)‐7‐hydroxyflavylium ion by continuous irradiation, flash photolysis, 1 H NMR spectroscopy, and stopped flow analysis. The distribution of the various forms at the pH‐dependent thermodyn…
With the ever-decreasing size of microelectronics, growing applications of superlattices, and development of nanotechnology, thermal resistances of interfaces are becoming increasingly central to thermal management. Although there has been much success in understanding thermal boundary resistance (TBR) at low temperat…
Silica, SiO2, is typically found in well water supplies. Most of the silica found in well waters is a result of dissolving silica-containing rock. Silica content in brackish water is generally in the range of 20 to 60 ppm. In Salbukh water treatment plant, silica concentration of raw water is about 30 ppm. High concen…
Zn2SnO4, which has an inverse spinel structure, was adopted as the host material of a new green emitting phosphor. The photoluminescent (PL) properties of a series of europium-activated zinc stannate synthesized by vibrating milled solid state reaction have been investigated. One broaden emission band from the Zn2SnO4…
The NADP(+)-preferring glucose dehydrogenase from thermoacidophilic archaeon Thermoplasma acidophilum has been characterized, and its crystal structure has been determined (Structure, 2:385-393, 1994). Its sequence and structure are not homologous to bacterial NAD(P)(+)-dependent glucose dehydrogenases, and its molecu…
It is shown that chromophores can be efficiently grafted on nanometer sized gold particles dispersible in an aqueous solution. The grafting is carried out in two steps: first, a primary grafting of thiols consisting both of stabilisers (2-mercaptoethane sulfonate and thiomaleic acid) and of linker molecules (4-mercapt…