Materials Literature
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Abstract Two biphenyl lignans, α ‐ and β ‐DDB ( 1 and 2 , respectively) were efficiently synthesized without contamination by other regio‐isomers. The different yields of the Ullmann coupling reactions for the synthesis of 1 and 2 were rationalized by calculating steric hindrance, stability, entropy change, and heat‐o…
The inhibition efficiency (IE) of various concentrations of a caffeine-Zn2+ system in controlling corrosion of mild steel immersed in an aqueous solution containing 60 ppm of Cl– was evaluated by a weight-loss study. The formulation consisting of 50 ppm of caffeine and 50 ppm of Zn2+ showed 91% IE. A synergistic effec…
In this work, the frequency relaxation of the dielectric permittivity of BaBi 2 Ta 2 O 9 (BBT) and BaBi 2 Nb 2 O 9 (BBN) ceramics is investigated in the wide temperature range. Both compositions feature behavior typical for relaxor ferroelectrics including the strong frequency dispersion of the permittivity, the prono…
Abstract The hydrothermal reaction of kaolinite in the system Na 2 O-K 2 O-(MgO)-Al 2 O 3 -SiO 2 - H 2 O has been investigated at 200 and 300 º C. The study of the solid products indicates that, at 200 º C, disordered illite was the first phase formed, which evolved at increasing run times towards well ordered illite…
Abstract Morphology and properties of poly(butylene terephthalate) (PBT)/nylon 6 (PA6)/EVA‐g‐MAH ternary blends were investigated. The blends were prepared in a corotating, intermeshing, twin‐screw extruder. The incorporation of maleic anhyride (MAH) grafted onto ethylene‐vinyl acetate copolymer (EVA) (EVA‐g‐MAH) in t…
Las muestras palinológicas de sedimentos holocenos provenientes de la laguna Hinojales (37º 34’" S; 57º 27’O), sudeste de la provincia de Buenos Aires, contienen algas (Chlorophyta, Cyanophyta and Dinoflagellata) y acritarcos. Las algas clorofíceas consisten en cenobios de Pediastrum musterii Tell y Mataloni,P. boryan…
Internal space charge measurement has been mainly applied to investigate insulating materials used in RV apparatus, such as HVDC cables. We have observed the space charge profiles to monitor copper ion migration occurring in an insulation layer of a metal-base printed circuit board and found that the space charge dist…
Abstract Aggregation of colloidal clay particles (Na-montmorillonite) by CaCl 2 and anionic polysaccharide (succinoglycan) in turbulent conditions was investigated using time-resolved size measurements by laser diffraction on diluted (50 mg l –1 ) and stirred suspensions. Excess of Ca 2+ ions promotes coagulation of t…
Abstract Raman spectrometry, UV–visible–near IR and attenuated total reflection IR absorptions are used to analyze the protonation of the emeraldine form of the phenyl/—NH 2 end‐capped BQBBa tetramer and of the phenyl/—NH 2 end‐capped (BQBB) 4 a hexadecamere in strong (H 2 SO 4 or HCl), intermediate (CH 3 COOH) and we…
Porous SiC ceramics were synthesized by sintering pressed and pressed/CIPed powder compacts of α‐Si 3 N 4 , carbon (Si 3 N 4 :C = 1:3 mol as ratio), and sintering aids, at 1600°C for few hours to achieve a reaction, and subsequently sintering at a temperature range of 1750°–1900°C, in an argon atmosphere. High porosit…
Improved X-ray powder diffraction data for orthorhombic phosphorus, S.G. C mca (64) obtained in situ at synthesis conditions of 1.2 GPa and 1100 K, are described. Representative, as synthesized, data include 2.552 X , 3.320 4 , 2.595 3 , 5.191 2 , 1.630 2 , for least-squares unit-cell a =3.3182(6) Å, b =10.3744(18) Å…
Copper and palladium complexes of new salicylaldimines derived from 3,4,5-tridecyloxyaniline, 2,3,4-tridecyloxyaniline and 4-decyloxyaniline have been synthesized and characterized. All the ligands bear four or more aliphatic chains with the aim of inducing columnar mesophases at low temperatures. In particular, metal…
We describe a new and unique method for simultaneous determination of the groove depth and duty cycle of binary diffraction gratings. For a near-normal angle of incidence, the +1 and -1 diffracted orders will behave nearly the same as the duty cycle is varied for a fixed grating depth. The difference in their behavior…
Nous avons caracterise un echantillon de nepheline provenant de Egan Chute, pres de Bancroft, en Ontario, ayant une composition (K 1 . 3 2 □ 0 . 6 8 )(Na 6 . 0 5 Ca 0 . 2 2 )[Al 7 . 7 7 Si 8 . 2 1 O 3 2 ], par diffraction X sur monocristal, microscopie electronique a transmission, analyses thermiques, et diffraction X…
Silicon nitride ceramics seeded with 3 wt%β‐Si 3 N 4 whiskers of two different sizes were prepared by a modified tape casting and gas pressure sintering. The fine whiskers had a higher aspect ratio than the coarse whiskers. Quantitative texture analysis including calculation of the orientation distribution function (O…
Abstract Ikaite is a metastable hexahydrate of calcium carbonate, forming in aqueous conditions near freezing conditions. Neutron powder diffraction data of synthetic deuterated ikaite, collected at seven temperatures from 4 to 270 K, were refined. The linear thermal expansion coefficients are quite anisotropic, being…
The corrosion rate in the splash and tidal zones of marine steel structures is very severe. Thermally sprayed coatings of zinc or aluminium and their alloys are among the most important technologies to eliminate this problem. This experimental study on the protective properties of thermally sprayed zinc and aluminium…
Abstract Novel peroxide‐crosslinked composite materials based on ultra high molecular weight polyethylene fibers were studied in comparison with their non‐crosslinked homologues. Two material types were prepared, either by embedding the fibers in a low‐density polyethylene matrix, or by compacting neat fibers. The res…
Abstract The proposed model is based on the simplified description of the thread structure, and it works with the textile description of thread structure. The following textile parameters are used in the model: fineness of fibres, and number of fibres at the cross-section in the bundle and the filling. The formation o…
Abstract Sisal fiber reinforced benzylated fir sawdust composites belong to a new category of composite materials, in which both the reinforcement and matrix are based on plant fibers, i.e. renewable resources. The present paper discusses the water absorption behavior of the composites and its influence on the mechani…