Nanostructure and giant Hall effect in TMx(SiO2)(1-x) (TM=Co,Fe,Ni) granular system

Granular TMx(SiO2)(1-x) (TM=Co,Fe,Ni) thin films were thermally treated at different temperatures and their magnetotransport and structural properties were studied. Hall resistivity decreases with thermal annealing. Structure was analyzed based on small angle x-ray scattering results. A model of polydisperse system of hard spheres was used for obtaining structural parameters. Analysis reveals that a volume fraction of transition-metal atoms (less than 29%) are forming nanospheres. Changes in giant Hall effect upon annealing can depend on a particular combination of nanoparticle diameter, interparticle distance, and size distribution. (C) 2006 American Institute of Physics.99

ANTIMONY(V) OXIDE GRAFTED ONTO A SILICA-GEL SURFACE - ACIDIC PROPERTIES AND THERMAL-STABILITY

Antimony(v) oxide grafted onto a silica gel surface was obtained in highly dispersed form, with antimony density of 0.65 atoms nm-2. The material presents Bronsted and Lewis acid properties different from pyrochlore, Sb2O5. These sites disappear upon thermal treatment at 500-degrees-C owing to reaction ot antimony oxide with the silica surface.88213193319

Controlling Fe nanocrystallization in amorphous Fe86Zr7Cu1B6 by linear varying current Joule heating

Amorphous melt-spun Fe86Zr7Cu1B6 ribbons were annealed using the linear varying current Joule heating method. Experimental curves of resistance (R) and temperature (T) versus applied current (I) allow one to follow precisely the crystallization of alpha-Fe nanoparticles during annealing. This result proves that the applied current can be considered a reliable parameter to control the crystalline fraction in this alloy. A comparison between structural and magnetic measurements shows that the R(I) curve can be used as a guide to identify a condition for optimum soft magnetic properties of this alloy. (C) 2000 American Institute of Physics. [S0003-6951(00)02035-0].7791375137

Two new sealed sample cells for small angle x-ray scattering from macromolecules in solution and complex fluids using synchrotron radiation

Two different vacuum tight sample cells for in situ temperature dependent small angle scattering from liquids are presented in this article. In the first one, the sample fills a 1 mm thickness gap sealed on both sides by two thin parallel mica windows (volume 300 mul). In the second one, the liquid is injected into a 1 mm cylindrical capillary tube (volume 130 mul). The cells are lodged into temperature controlled chambers directly connected to the beamline vacuum path. Several important improvements with respect to similar instrumentation previously reported are: (1) versatile application of the mica cell, that can be used for all types of samples (gels, liquid crystals, and dispersions in organic solvents) and (2) the design of the chamber for the capillary cell allows registration of wider angle data and a convenient replacement of the capillary tube after each experiment. Signal to background ratio and data reproducibility were tested using protein solutions. We give a brief report of scattering experiments performed with different protein samples and two-dimensional data collection. (C) 2004 American Institute of Physics.75114541454

CRYSTALLITE SIZE DETERMINATION IN MU-C-GE FILMS BY X-RAY-DIFFRACTION AND RAMAN LINE-PROFILE ANALYSIS

Experimental Raman spectra were used to evaluate the average crystallite size of muc-Ge films. The experimental curves were fitted with a theoretical expression obtained by Richter et al. assuming a Gaussian size distribution. X-Ray Diffraction line profile analysis was performed to obtain crystallite size and shape information. Comparison of the results from both techniques proves that the crystallite dimensions obtained can only be expected to be similar in those cases in which the approximation of ''spherical'' grains is valid.85430731

Thermotropic phase behavior of DPPC liposome systems in the presence of the anti-cancer agent 'Ellipticine'

This letter presents our first results on the structural changes in DPPC multilamellar vesicles dispersed in water in the presence of the anti-cancer agent Ellipticine. The thermotropic phase transitions of the lamellar packing inside lipid vesicles were characterized in situ by small angle X ray diffraction. The results lead to the determination of a critical concentration value for drug loading on the vesicle system around 4% molar fraction of Ellipticine, an indication of the localization of the drug in the alkyl chains and the influence of the drug on the decreasing rate of the bilayer period after the main phase transition.361677

Lipid model membranes for drug interaction study

The present work shows a structural study on the process of incorporation of a hydrophobic drug, Ellipticine (ELPT), into lipid model membranes for drug targeting purpose. The ELPT is an alkaloid that showed an anti-proliferation activity against several types of tumor cells and against the HIV1 virus. We used the zwitterionic lipid dipalmitoyl phosphatidylcholine (DPPC) and four different anionic lipids: cardiolipin (CL), dipalmitoyl phosphatidic acid (DPPA), dipalmitoyl phosphatidylglycerol (DPPG) and dipalmitoyl phosphatidylserine (DPPS), both spread on a Langmuir monolayer and deposited on a solid substrate to mimic a model membrane and study the interaction with the drug ELPT. X-ray reflectivity results pointed toward an increase in drug loading efficiency up to 13.5% mol/mol of ELPT into mixed systems DPPC/CL. This increase in loading efficiency was also accompanied by a slight distortion in the stacking of the bilayers less evidenced after optimization of the molar ratio between the co-lipids. Grazing incidence X-ray diffraction measurements revealed an in-plane lattice distortion due to the presence of hydrocarbon chain backbone ordering in pure systems of DPPC doped with ELPT. The same was not observed in mixed membranes with DPPC/CL and DPPC/DPPA.35543143

Poly(n-alkylsilsesquioxane)s: Synthesis, Characterization, and Modification with Poly(dimethylsiloxane)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Self-supported translucent films constituted of poly(n-octylsilsesquioxane) or poly(n-dodecylsilsesquioxane) were obtained from the hydrolysis and condensation of n-octyltriethoxysilane (OTES) or n-dodecyltriethoxysi lane (DTES), respectively. Dense films were obtained in the absence of organic solvents, with dibutyltin diacetate as catalyst. These films exhibited good optical transparency and thermal stability. The incorporation of oligomeric dimethylsiloxane units (D(Me,Me)) in these materials, derived from silanol-terminated poly(dimethylsiloxane) (PDMS) or 1,1,3,3-tetramethyl-1,3-diethoxydisiloxane (TMDES), was carried out during the hydrolysis and condensation of OTES and DTES and was confirmed by solid-state (29)Si NMR. Poly(n-octylsilsesquioxane) showed a glass-transition temperature at -65 degrees C, due to the increase in the free volume, promoted by the bulky n-octyl groups. The differential scanning calorimetric (DSC) curves of the polymer derived from DTES were characterized by first-order transitions at temperatures ranging from -15.8 to -0.7 degrees C. Further studies of these networks by low-temperature XRD evidenced narrowing of the diffraction halos suggesting a partial order-disorder transition for these materials at lower temperatures. Good thermal stability up to 350 degrees C and the solvent-free production process make these polymers potential candidates for the development of self-supported hydrophobic protective coatings. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1220-1229, 201048512201229Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [03/09, 962-1]CNPq [305916/2006-8

INFLUENCE OF THE SUBSTRATE ON THE CRYSTALLINE PROPERTIES OF SPRAYED TIN DIOXIDE THIN-FILMS

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