Cholesteric and other phases in thermotropic liquid crystalline polymers with side chain mesogenic groups
Abstract
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The role of graphite in the thermal shock resistance of refractories
On etudie les facteurs contribuant a l'excellente resistance aux chocs thermiques des refractaires contenant du graphite: dilatation thermique, module d'elasticite, mecanisme de rupture, deformation, conductivite thermique
Mechanical properties of manganese sulphides in the temperature range between room temperature and 1000.DEG.C.
Manganese sulphide powders, prepared by a sulphur deoxidation of MnSO4, were melted at 1700°C in a graphite crucible, and then solidified into buttons, about 20mm diameter and 15mm long. Several kinds of bulk manganese sulphide with additives were prepared from powder mixtures of MnS and one of Al2O3, SiO2, MnO, CaO,…
Contamination Studies on Mollusk Shell Samples
A series of shell samples has been studied to determine the magnitude and mechanisms of carbon exchange between shells and their environment. Laboratory contamination experiments included the storing of shell samples in acid and calcareous environments of different 14 C concentrations as well as studies of carbon exch…
Magnetic properties of metastable Fe-Al alloys produced by vapor quenching.
Fe-Al alloy films have been obtained by rf sputtering technique and have been investi. gated by means of X-ray diffraction, magnetization and Mössbauer effect measurements A well disordered bcc phase is extended up to about 70at % Al, an amorphous phase between 75 and 85at % Al and an fcc phase from 90 to 100at % Al.…
Characterization of solid polymers by luminescence techniques
Abstract
The molecular structure of monomeric base-free bis(neopentyl)manganese by gas electron diffraction
The gas electron diffraction pattern of bis(neopentyl)manganese is consistent with a monomer with ∠CMnC = 180° and Mn–C = 210.4(6) pm.
Isolation and characterization of the principal kinetic product in the preparation of a sterically hindered tetra-arylporphyrin: X-ray structure of a bis(dipyrromethene) complex of zinc, Zn II (C 22 H 13 Cl 4 N 2 ) 2 · toluene
The principal kinetic product in the Rothemund template synthesis of sterically hindered tetra-arylporphyrins is not the metalloporphyrin complex but the bis(dipyrromethene) complex; the latter has been isolated from a typical porphyrin preparation, that of tetrakis(2,6-dichlorophenyl)porphyrin, and characterized by u…
Structure–property correlations in some nematic main–chain polyesters
The homologous series of thermotropic nematic main-chain polyesters [graphic omitted] has been investigated. In the case of even values of n, a smectic phase appears at n= 18. An odd–even oscillation of nematic order parameters associated with the mesogen is observed near the clearing temperature, Tc. At the same time…
Structural analysis of liquid formamide
The structure of liquid formamide has been examined by X-ray analysis. It is concluded that there are distorted ring dimers which consist of hydrogen-bonded formamide molecules in the liquid state. The most likely model is similar to the crystal structure of formamide.
Kinetics and mechanism of the reactions of PH3 with O(3 P) and N(4 S) atoms
The reactions of ground-state oxygen and nitrogen atoms with phosphine have been studied using a discharge-flow system with detection of both free-radical and molecular species by molecular-beam sampling mass spectrometry. By observing the decay of PH3 in an excess of O, the rate constant for the reaction O + PH3 [gra…
Pyridine-metal complexes
Essentials of Coordination Chemistry. Sigma Pyridine Coordination Compounds with Nontransition Metals. Sigma Pyridine Coordination Compounds with Transition Metals. Coordination Compounds of Metals with Pyridine--l----Oxides. Pi--Coordination Compounds of Pyridine with Metals. Pyridine Intercalation Compounds. Clathra…
Frustration in polymers
The local configuration of polymers results from a competition between entropy effects and attractive forces which provide a high density. The resulting frustration is studied geometrically in a curved space representation reminiscent of the curved space representation for blue phases. Within this frame work, we study…
Progress in thermal plasma deposition of alloys and ceramic fine particles
Abstract
Fatigue Properties of Type 304 Stainless Steel in High Pressure Hydrogen at Room Temperature
The fatigue properties of the soluted and the sensitized type 304 stainless steel were investigated in high pressure hydrogen up to 4.0 MPa at room temperature. It is found that both the number of cycles to failure and the fatigue limits of the soluted and the sensitized steel decreased with increasing hydrogen pressu…
Electron optical synthesis and optimization
A novel approach to electron/ion optical synthesis and optimization is presented. Low-aberration field distributions are sought by dynamic programming or optimal control procedures in the form of continuous curves constructed of cubic splines. A very simple algorithm is proposed for the reconstruction of the electrode…
Tuning of reactivity in epoxidation of alkenes by iron and ruthenium complexes associated to non-porphyrinic ligands
RuCl3·n(H2O) or FeSO4 associated with bipyridyl or substituted phenanthrolines, catalyse the expoxidation of stilbenes by IO4– or ClO–; using phenanthrolines bearing electron donating or withdrawing groups, it is possible to modulate the reactivity of these systems.
Surface Analysis of Gas Atomized Ferritic Steel Powder
The surface of gas atomized ferritic powder, Fe–25Cr, was studied by ESCA and Auger spectro- scopy. During atomization reaction products are formed on the surface of the powder. Due to the very low oxygen potential in the atomizer only oxides of the strong oxide forming elements Cr, Mn, and Si are formed during coolin…
Octahedral Compositions of Individual Particles in Smectite-Palygorskite and Smectite-Sepiolite Assemblages
Abstract Chemical analyses were carried out on individual particles in <2-μm size fractions to study smectite-palygorskite and smectite-sepiolite assemblages extracted from calcareous and dolomitic continental formations in Provence, southeastern France. A plot of the octahedral composition of 145 individual pa…
Chapter 9. Conduction electron spin resonance in metallic systems
R. N. Edmonds, M. R. Harrison and P. P. Edwards, Annu. Rep. Prog. Chem., Sect. C: Phys. Chem., 1985, 82, 265 DOI: 10.1039/PC9858200265