Materials Literature
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Apesar das modernas e sofisticadas técnicas disponíveis, procedimentos de extração seletiva ainda são de considerável valor para a caracterização dos solos e para o entendimento dos processos pedogenéticos, sobretudo em ambientes e solos pouco estudados, como as restingas e os Espodossolos no Brasil. A aplicação dessa…
The first series of alkali dipyrrinato complexes is reported, encompassing lithium, sodium, and potassium salts of meso-unsubstituted and meso-aryl-substituted derivatives. By varying the substituents at the meso position, the intermolecular distance between the two nitrogen atoms and thus the κ 2 -N,N-bidentate bite…
It was studied the influence of gold addition on physico-chemical properties and catalytic activity of bimetallic Ni-Au/Al 2 O 3 catalyst in partial oxidation of methane (POM). The reduction behavior in hydrogen, XRD crystal structure, XPS spectra and POM catalytic activity were investigated. The reduction of Ni-Au ca…
Recent studies have indicated that amorphous silica particles (SPs) show cytotoxicity against various types of cells, including macrophages. However, the mechanism of cell death has not been determined, and systematic investigations of the relationship between particle characteristics and cytotoxicity are still quite…
In a future D/T fusion reactor the walls of the vessel containing the magnetically confined hot plasma have to stand simultaneously very high power, particle and neutron loads. In today’s high temperature plasma experiments at the areas of the highest load, i.e. the divertor and the limiters, W, Mo and Carbon (CFC) ar…
The effects of extracts of the aerial part of Blumea riparia DC. and their phenolic acids on hemostasis were evaluated. The EtOAc fraction showed significantly reduced blood clotting time (CT) and tail bleeding time of transection (BT) of mice in vivo. This fraction contained vanillic acid (1), syringic acid (2), p-co…
The paper presents a comprehensive numerical analysis of x-ray and neutron scattering from finite-conducting rough surfaces which is performed in the frame of the boundary integral equation method in a rigorous formulation for high ratios of characteristic dimension to wavelength. The single integral equation obtained…
The objective of this paper is to investigate the predictability of air permeability of cotton woven fabrics from their construction variables by using a feed-forward back-propagation network in an artificial neural network (ANN) system. In order to achieve this objective, a number of grey cotton fabrics meant for shi…
The mechanism of the chemiluminescent condensation of aniline with butyraldehyde into 3-ethyl-2-propylquinoline catalyzed by LnCl3 · 6H2O (Ln = Tb, Ho) is reported. A likely scheme of the catalytic condensation of aniline with butyraldehyde has been developed by simulation of separate steps of the reaction using chemi…
Differential-scanning calorimetry in the dynamic mode was used to study the curing kinetics of a PDI-3AK macromolecular oligodieneurethane-epoxy oligomer with isomethyltetrahydrophthalic anhydride in the presence of a number of catalysts, modifiers, and fillers. The effect of their chemical nature on physicomechanical…
Zinc-oxide-based ceramics were prepared by uniaxial hot pressing and their optical properties and luminescence-scintillation characteristics (for X-ray and gamma excitation) have been studied. The ceramics exhibit 35% transmission in the region of maximum wavelength of X-ray-induced luminescence (520 nm); an absolute…
Space borne observation requires extremely high resolution systems with large dimensions. The design of such systems implies associating sensing and actuation systems to insure a highly stable positioning of optical components. However, the currently used PZT materials for piezoelectric actuation show strongly diminis…
Abstract Iodine(III) chloride and free base para‐substituted meso‐tetraarylporphyrins (H 2 t(4‐Xp)p, X = OCH 3 , CH 3 ,CH(CH) 3 , H, Cl) react at mild conditions for formation of [(ICl 3 )H 2 t(4‐Xp)p] molecular complexes. The very close correspondence between the UV‐VIS and ( 1 H, 13 C) NMR spectra of these complexes…
Abstract Atomic distribution, thermodynamic stability of solid solutions and properties of dislocations in steels are discussed in terms of the effect of carbon, nitrogen and hydrogen on the electronic structure of iron. It is shown that nitrogen and hydrogen increase the density of electron states at the Fermi level,…
The conformation and arrangement of poly(ethylene oxide) (PEO) chains in clay galleries is still controversial. In our work, various spectroscopic methods have been used to explore the conformation of PEO in clay galleries. The melt intercalation process is investigated using variable-temperature Raman spectroscopy. I…
High-quality ceramics were synthesized on the basis of Bi1 − x A x FeO3 (A = La, Nd; 0.00 ≤ x ≤ 0.20) solid solutions. Their crystal and grain structure, Mössbauer spectra, and other dielectric and magnetic characteristics were studied. It was shown that an increase in the content of A elements in the studied samples…
Abstract Thiol‐functionalized meso‐structured silicas have been prepared by the co‐condensation of tetraethoxysilane and 3‐mercaptopropyltrimethoxysilane in the presence of an amphiphilic block copolymer (EO) 45 ‐ b ‐(MA) 53 . Partial S‐alkylation of mercapto groups with 9‐(chloromethyl)anthracene resulted in the form…
Abstract The crystal structure of Gd(CO 3 )OH was solved using synchrotron powder X‐ray diffraction. Gd(CO 3 )OH was known to exist in a form Gd 2 O(CO 3 ) 2 ·H 2 O and its powder pattern has been listed in JCPDF (#430604) for decades, but the crystal structure has not yet been elucidated. The crystal structure is sol…
The 3D problem of scattering by a grating consisting of coaxial impedance bodies of revolution is solved with the help of the modified null field method. A system of integral equations is derived, and numerical results are obtained for the scalar and vector formulations of the problem.
Small calibre (〈6mm) polytetrafluoroethylene (PTFE) bypass grafts have poor medium and long term patency due to the development of neointimal hyperplasia at the distal anastomosis. The inelasticity of PTFE is implicated in this mechanism of failure. We have developed a novel polyhedral oligomeric silsesquioxane (POSS)…