Materials Literature
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Reaction of LK (L = HC(CMeNAr) 2, Ar = 2,6- i Pr 2 C 6 H 3 ) and MnCl 2 (THF) 1.5 in THF unexpectedly resulted in the formation of the trinuclear complex LMn( μ -Cl) 2 Mn(THF) 2 ( μ -Cl) 2 MnL ( 1 ) in good yield. The substitution reactions of 1 with C 3 H 5 MgCl and PhCCLi, respectively, provided the monomeric LMnC 3…
Neste trabalho foi realizado um estudo de avaliação da degradação "in vitro" da blenda biorreabsorvível poli(beta-hidroxibutirato) (PHB) / poli(L-ácido lático) (PLLA). As blendas PHB/PLLA na forma de filmes, nas composições 0/100, 30/70, 50/50, 70/30 e 100/0 (% em massa), foram obtidas pelo método de evaporação do sol…
The effect of an external electric field on the grain‐growth behavior of acceptor Mg‐doped, undoped, and donor Nb‐doped BaTiO 3 ceramics was investigated. The acceptor‐doped and undoped specimens showed enhanced grain growth at the positive‐biased region. On the other hand, for the highly donor‐doped specimens, grain…
Experimental studies of the fracture kinetics of polycrystalline metals have led to the problem of the barrier and activation volume of elementary fracture acts. A model is proposed where the field binding one atom to its environment in a metal is represented by equivalent bonds directed along three orthogonal axes. T…
Abstract This work is a part of a series on surface modification of materials made of chitosan. This report focused on grafting monomethoxy ethylene glycol oligomers (mPEG) on the surface of chitosan films. The chemical reactions were performed by immersing the films in organic solvent containing aldehyde derivative o…
The determination of the local mass per unit area m/A=∫ρdt and the thickness of a specimen is an important aspect of its characterization and is often required for material quality control in fabrication. We discuss common methods which have been used to determine the local thickness of thin specimens. We then propose…
Abstract The Izod impact strength and tensile elongation‐to‐break were measured for blends of nylon 66 and polystyrene in a polypropylene matrix with and without compatibilization by an ionomer resin (for nylon 66) and a styrene‐ block ‐ethylene‐ co ‐butylene‐ block ‐styrene copolymer (for polystyrene). With 20% nylon…
A delayed exotherm was recorded during the reduction of a carboxylic acid with BH 3 ·THF. This article will describe our efforts to explain and control the observed exotherm using a reactor integrated with a mass-flow meter, a reaction calorimeter, and an in situ FT-IR probe. In the end, a kinetic model is proposed th…
Quaternary strontium copper(I) lanthanoid(III) selenides are formed by the oxidation of elemental strontium, copper and the corresponding lanthanoid with selenium. Orange to red needle-shaped single crystals of SrCuPrSe 3 and SrCuCeSe 3 have been synthesized by heating mixtures of Sr, Cu, Pr / Ce and Se with CsI as a…
In the course of research on the diatoms from surface sediments sampled in the marine littoral and sublittoral worldwide, and in some freshwater localities in central Europe, several problematic taxa were encountered resembling Nitzschia parvula. We therefore undertook a light and scanning electron microscopical study…
Pulsed laser deposition has been used to grow Pt(621) thin films having a chiral orientation on SrTiO3(621) substrates. Films were deposited over a range of conditions, then characterized for their crystallinity and epitaxy using x-ray diffraction and for their surface morphologies using atomic force microscopy (AFM).…
Nanocomposites were prepared from styrene butadiene rubber (SBR) having different styrene contents and octadecyl amine modified Na‐montmorillonite clay (OC). The modified and the unmodified clays were characterized with the help of X‐ray diffraction technique (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and T…
In the present work, we report the epitaxial growth and dielectric properties of barium strontium titanate (BST) thin film which can be used to make frequency and phase agile tunable microwave (MW) components with a high performance, such as tunable filters, tunable oscillators, and phase shifters for application in p…
The <IMG SRC="/fbpe/img/jcchems/v49n3/alfa.jpg" WIDTH=12 HEIGHT=12>-pinene isomerization reaction was studied on catalysts based on H3PW12O40 (HPW) supported on TiO2, SiO2 and ZrO2nH2O. Catalysts with a 40% nominal charge of phosphotungstic acid (HPW) were prepared by impregnation of supports with a HPW solution…
Abstract Diffusion couples and equilibrated alloys have been investigated in order to contribute to the knowledge of Ti–Zn phase diagram. Differential scanning calorimetry, X-ray methods and scanning electron microprobe analyses are applied. Diffusion couples studies show that TiZn3 layers grow directly from the Ti–Zn…
The effects of incorporation of lanthanum (La 3+ ) ions in Na 1/2 Bi 1/2 TiO 3 (NBT) on microstructure and sintering characteristics were studied. As the content of incorporated La 3+ increased in [(Na 0.5 Bi 0.5 ) 1-1.5 x V 0.5 x La x ]TiO 3 , the sintered density reached a maximum at x =0.05 and the grain size decre…
Photo-induced phenomena in glasses excited by two-photon absorption have been studied and compared with those produced by bandgap illumination. The two-photon excitation of As2S3 gives a refractive-index increase, unaccompanied by photodarkening. Raman-scattering spectra show that the excitation increases the density…
The photogeneration of Ag particles and clusters with 350 nm photons was studied in thin films containing poly(vinyl alcohol) and poly(acrylic acid) that were crosslinked with glutaraldehyde. Product formation occurred through two consecutive processes that were linear functions of time. Kinetic determinations showed…
Blue and ultraviolet upconversion (UC) emissions at 455 and 363nm were observed from Tm3+ doped fluoroindate glasses pumped at 650nm. The time behavior of the UC signals was studied for different Tm3+ concentrations. The measurements revealed the origin of the UC process as well as allowed to quantify the interaction…
Domain wall structures on the etched surfaces of the solid solutions of Pb(Zn 1/3 Nb 2/3 )O 3 - x PbTiO 3 (PZN- x PT; x =8%, 20%) were investigated by atomic force microscopy (AFM). Ferroelectric and ferroelastic domain wall structures were observed. In the rhombohedral phase, a zigzag domain wall structure was found.…