Materials Literature
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[structure: see text] A versatile stepwise synthetic approach to cofacial bis-porphyrin species with calix[4]arene spacers has been designed. The three examples described demonstrate that the method allows selection, in a tailor-made fashion, of the calix[4]arene conformation, the type of functionalization of the cali…
We show that recent claims of experimental verification of a negative index of refraction in metallic metamaterials, "left-handed" microwave frequencies, are questionable. At these frequencies the imaginary part of the dielectric permittivity is significant or even dominates its real part, and hence the effective medi…
The structure of a new iodate, (LiFe 1/3 )(IO 3 ) 2 , has been determined. The new compound has a hexagonal structure with the lattice parameters a =5.4632(2) Å, c =5.0895(6) Å, Z =1. The density is 4.70 g cm −3 . Rietveld refinement confirms that the compound has a space group of P 6 3 (173). Fe and Li atoms randomly…
The corrosion behaviour of mild steel in 2M hydrochloric acid solution containing various concentrations of condensation products formed from glutaraldehyde + glycine (CP1) and glutaraldehyde + methionine (CP2) has been investigated using weight loss measurement and galvanostatic polarization technique. The percentage…
X-ray diffraction techniques have been applied to study the crystallization of poly(ethylene-2,6-naphthalate), PEN. Uniaxial and biaxial orientation of amorphous cast PEN films resulted in stress-induced crystallization of the triclinic α-PEN polymorph. Annealing of the amorphous PEN samples in the range of 160–240 °C…
The crystallization of a confined short polyethylene chain, n-tetracontane, quenched from the melt has been investigated by a dynamic Monte Carlo method on a high coordination lattice. The periodic boundary conditions force the formation of a free-standing nanofiber exposed to a vacuum. After the deep quench, the nano…
Molecular dynamics simulations were used to model the incorporation of magnesium, cadmium and strontium ions at two stepped (10 1 4) surfaces of the calcium carbonate polymorph calcite. The potential model used in the simulations was derived to reproduce experimental enthalpies of CaCO 3 , MgCO 3 , CdCO 3 and SrCO 3 f…
A condutividade térmica é uma das propriedades físicas mais importantes de um material. A sua determinação experimental apresenta algumas dificuldades e requer alta precisão na determinação dos fatores necessários para o seu cálculo. O método de medida de condutividade térmica para materiais refratários mais usado hoj…
The effect of Ca modification on the corrosion properties of weathering steel was investigated by pH measurement, electrochemical impedance spectroscopy (EIS), and cyclic corrosion testing. The pH measurement and EIS were performed with a thin water film covering the steel. Test results showed that the addition of Ca…
Abstract 9-Arylxanthen-9-ylium (3a–i) and 9-arylthioxanthen-9-ylium (4a,b,e–i) perchlorates [aryl = 2,4,6-(MeO)3C6H2 (a), 2,6-(MeO)2C6H3 (b), 2-MeOC6H4 (c), 4-MeOC6H4 (d), 3-Br-2,6-(MeO)2C6H2 (e), 2,4,6-Me3C6H2 (f), 2-MeC6H4 (g), 4-MeC6H4 (h), C6H5 (i)] were prepared by the reactions of 9-arylxanthen-9-ols or 9-arylth…
Abstract The effect of ionic radius of trivalent rare earth cations (RE3+) on the population at two square-antiprismatic sites (Site I and Site II) in [(RE)2(H2O)2(SbW9O33)(W5O18)2]15- was studied by luminescence spectroscopic and X-ray crystallographic measurements in the Eu/Y- and Eu/Lu-mixed systems. The results in…
Abstract Cyclohexane partial oxidation over a 40‐mesh Pt–10% Rh single‐gauze catalyst can produce ∼85% selectivity to oxygenates and olefins at 25% cyclohexane conversion and 100% oxygen conversion, with cyclohexene and 5‐hexenal as the dominant products. A detailed 2‐D model of the reactor is solved using density‐fun…
The crystal structures of two manganese hexacyanometallates(II), Mn 2 [Fe(CN) 6 ].8H 2 O and Mn 2 [Os(CN) 6 ].8H 2 O, were refined from X-ray powder diffraction data using the Rietveld method, with the reported structure for Mn 2 [Ru(CN) 6 ].8H 2 O used as a structural model. These compounds are isomorphous and crysta…
The study of heat exchanger fouling using supersaturated calcium sulphate solutions has been widely reported. In this study fouling was investigated in a larger-scale heat exchange apparatus using stainless-steel pipe, and data were obtained at different flow rates, concentrations and temperature differences. The depo…
Aiming to resolve some of the problems regarding monitoring of heavy metals in rivers using Cladophora glomerata and epilithic algal communities, a year’s survey of Co, Cd, Cu, Fe, Mn, Pb and Zn has been conducted on the river Vardar, FY Republic of Macedonia. Obtained results and statistical analysis clearly point ou…
The local environment of Nd‐O in a sodium tellurite glass was elucidated as a function of Nd 2 O 3 concentration, from 0.1 to 2.5 mol%, using optical spectroscopy. The Judd‐Ofelt (J‐O) theory was used to determine the oscillator strength parameters (J‐O parameters) of the glasses. According to the J‐O parameters, a si…
First-principles all-electron total-energy calculations of the structural and electronic properties for the group-IV zincblende-like compounds GeC, SnC using the full-potential linearized plane wave (FP-LAPW) approach within the density functional theory (DFT) in the local density approximation (LDA) and the generaliz…
A refratariedade e a resistência ao choque térmico dos materiais estão intrinsecamente ligadas às fases que os compõem, de modo que a identificação destas fases através da técnica de difração de raios X é atualmente imprescindível para a completa caracterização de matérias-primas de produtos cerâmicos. Em 1969, H. M.…
Nous avons affine la structure cristaline de l'ushkovite, triclinique, a 5.3468(4), b 10.592(1), c 7.2251(7) A, a 108.278(7), β 111.739(7), γ 71.626(7)°, V 351.55(6) A 3 , Z = 2, groupe spatial P1, jusqu'a un residu R de 2.3% en utilisant 1781 reflexions observees mesurees avec rayonnement MoKa. Le meme cristal a par…
The size reduction by dispersers in the liquid phase was investigated for different energetic materials such as hexogen (RDX), octogen (HMX), 3-nitro-1,2,4-triazole-5-one (NTO), hexanitrostilbene (HNS), ammonium nitrate (AN) and hexanitrohexaazaisowurtzitane (CL20). Two different dispersers, an ultrasonic device and a…