Search

The self-assembled monolayers (SAMs) process is one of the techniques used for the production of ultra-thin layers. The present work is therefore devoted to the study of the inhibition of zinc corrosion in a marine environment rich in H2S by SAMs based on Sargassum fluitans III. The protective effect of crude extracts of Sargassum fluitans on the surface of zinc using the SAMs process was evaluated by gravimetry and impedance on two different sites after three months of exposure. The formation of SAMs was characterized by FTIR, and the corrosion products formed on the surfaces were analyzed by XRD. The results obtained show that SAMs based on Sargassum fluitans III effectively inhibit zinc corrosion. [ABSTRACT FROM AUTHOR]

The microstructure evolution of Mg-13Gd-4Y-2Zn-0.5Zr (wt.%) alloy with long-period stacking ordered (LPSO) phases after compression-torsion deformation (thereinafter referred to as CT deformation) at different temperatures was analyzed by optical microscopy (OM), scanning electron microscopy (SEM), x-ray diffraction (XRD) and electron back-scatter diffraction (EBSD) analysis, especially the evolution of LPSO phases during CT deformation. In addition, dynamic recrystallization (DRX) behavior during CT deformation and the impact of LPSO phase evolution on DRX behavior was explicated. The results showed the structures by order of appearance: lamellar LPSO phase (light kink—moderate kink—severe kink—almost no kink) and bulk LPSO phase (needle-like projections—tearing—dissolution—crushing) at increased CT deformation temperature. The proportion of DRXed grains gradually increased with CT deformation temperature, ranged from 11.6% at 350 °C to 40.9% at 480 °C. Apart from the increases in atomic thermal vibration and diffusion rate owing to increase in CT deformation temperature, the bulk LPSO phases at the grain boundary showed enhanced lattice rotation, which provided an ideal position for the nucleation of DRXed grains, and promoted the accumulation of strain gradient during deformation. Meanwhile, the second-phase particles distributed in the grain and grain boundary promoted DRX nucleation through PSN mechanism. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Dental Science is the property of Brazilian Dental Science Journal-ICT-UNESP and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, we report the effect of Nickel (Ni) nanoparticles (NPs) concentrations on the morphological, magnetic and mechanical properties of low-density polyethylene (LDPE) polymer matrix. Ni nanoparticles were prepared by solvothermal method. LDPE/Ni nanocomposites (NCs) films were prepared by solution mixing method for different Ni content (1, 3, 5, and 10 wt %). X-ray diffraction analysis indicates that, Ni NPs enhance the crystallinity of the polymer nanocomposite. Nanoindentation analysis of LDPE/Ni revealed an increase in hardness, indicating enhanced nanomechanical elastic properties. The magnetic properties of nanocomposite revealed a soft ferromagnetic behavior at room temperature. LDPE/Ni magnetic nanocomposites have shown potential for the development of materials with unique and tunable magnetic and mechanical properties. [ABSTRACT FROM AUTHOR]

Orange peels (Citrus sinensis) are an abundant lignocellulosic residue that can be used as a carbon source to obtain solids with catalytic potential in the transformation of terpenes and their oxides into value-added products. This research seeks to evaluate the isomerization of a-pinene epoxide to campholenic aldehyde using a catalyst obtained from orange peels. The material OAC-Zn was obtained by activation of orange peel with ZnSO4.7H2O followed by thermal treatment at 500 °C; an additional solid was obtained from orange peel by pyrolysis at 500 °C (OC-500). XRD revealed the presence of ZnO and ZnS in OAC-Zn; TGA analysis indicated thermal stability in OAC-Zn and OC-500 materials; SEM images showed porous surfaces of different morphology, and the presence of microporosity in OC-500 and mesoporosity in the OAC-Zn that was confirmed by physical nitrogen adsorption. The elements C, O, Zn and S were identified in OAC-Zn by EDX analysis. The results of TPD-NH3 showed that the solids contained medium and weak acidity. Campholenic aldehyde was synthesized with a 96 % selectivity over the material OAC-Zn. [ABSTRACT FROM AUTHOR]

Copyright of Romanian Journal of Materials / Revista Romana de Materiale is the property of Foundation for Materials Science & Engineering Serban Solacolu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista del Museo de Antropología is the property of Museo de Antropologia - IDACOR and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The reaction of 2-aminothiazole C3H4N2S with tricarbonyl (1-4- η -5- N -pyridiniocyclohexa-1,3-diene) iron tetrafluoroborate complex [C11H12NFe(CO)3]+[BF4]− 1 , a precursor of the highly reactive cation [Fe(CO)3(1-5- η -C6H7)]+, afforded a new tricarbonyl (1-4- η -5- N -2-aminothiazoliocyclohexa-1,3-diene) iron complex of formula C9H10N2S Fe(CO)3 2. The structure of this complex was characterized by IR, 1H NMR spectroscopy and single crystal X-ray diffraction analysis which showed that the labelled complex 2 adopts an exo-enantiomer. In the crystal packing, the components of the structure are linked via intermolecular N–H⋯N hydrogen bonds to form dimeric chains running along the b axis direction. The antimicrobial activity of the free ligands 2-aminothiazole showed significant antibacterial activity. After labeling them, this activity has increased for the complex 2. [ABSTRACT FROM AUTHOR]

Copyright of Ceramica is the property of Associacao Brasileira de Ceramica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract A new iron phosphate Li 0.75 Mn 1.50 Fe 1.75 (PO 4 ) 3 has been prepared by the flux method and its structure was characterized from single crystal X-ray diffraction data. It crystallizes as an alluaudite type structure, characterized by the A(2)A(2)’A(1)A(1)’A(1)”M(1)M(2) 2 (PO 4 ) 3 general formula with a = 12.002(9) Å, b = 12.509(9) Å, c = 6.404(7) Å, β = 115.07(7)° in the monoclinic C 2/ c space group. The 3D framework consists of infinite chains of edge-sharing M(2) 2 O 10 dimers and M(1)O 6 octahedra connected by phosphate tetrahedra leading to two sets of hexagonal tunnels. The Li+ and Mn2+ ions partially occupy one of them, the other tunnel being empty. The Mössbauer spectroscopy confirmed the occurrence of only Fe3+ ions in octahedral environment. Electrochemical cycling tests in Li cells were performed using Li 0.75 MnII 1.50 FeIII 1.75 (PO 4 ) 3 powder as electrode material. Only a small amount of Li+ ions can be reversibility deintercalated/intercalated corresponding to a capacity as low as 30 mAh/g with a 3.2 V average voltage. Moreover, a strong polarization due to low electronic and ionic conductivities is observed. The presence of Mn2+ ions in the same tunnel as Li+ probably hinders a good Li+ ionic diffusion. Graphical abstract Li.75 Mn 1.50 Fe 1.75 (PO 4 ) 3 : synthesis, structure and electrochemical performances as positive electrode for Li-ion batteries. fx1 [ABSTRACT FROM AUTHOR]

The first component for the manufacture of masonry products used in construction is clay, which provides the plasticity that facilitates the molding and handling of the product. The second component is the feldspar in form of alumina (Al2O3) which is used as flux. The third one is silica (SiO2) which is used as a filling material and stabilizer. These elements are determined by chemical composition using fluorescence analysis or X-ray diffraction, which is the basis of the modern classification of minerals. Thereby, the main objective of this research is to study the surface characteristics of clay samples from an industrial company producing H-10 blocks in the region of Norte de Santander, by studying the surfaces of the samples selected through the analysis by Atomic Force Microscopy, in order to compare the results with those found in the literature, and at the same time taking into account the chemical elements in their highest composition. The results show that this is a technique that allows the identification of clay components, thus validating what has been found in physical and chemical analysis, expecting to provide a scientific contribution by AFM, because there is little information related to the characterization topography of clay materials. [ABSTRACT FROM AUTHOR]

Bones from Tlatelcomila (Tetelpan, México D.F.) were characterized by several complementary physical and chemical techniques, such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, energy-dispersive spectroscopy and ultraviolet spectroscopy, to determine whether they were boiled or grilled. The usual correlation between thermal treatment and colour is revisited in terms of microscopic structure, morphology and texture. At temperatures less than 100°C, it is shown that colour depends not only on temperature or diagenesis but also on the cooking procedure; that is, on the presence of spice dyestuffs such as axiote (Bixa orellana) or chilli (Capsicum). [ABSTRACT FROM AUTHOR]

Copyright of Ceramica is the property of Associacao Brasileira de Ceramica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this work, structural and morphological properties of vanadium doped zinc oxide (ZnO:V) pellets with different percentage of vanadium (2–10%) obtained by sol gel method have been investigated by X-ray diffraction, Raman spectroscopy and atomic force microscopy. XRD analysis showed that this samples are polycrystalline with a hexagonal wurtzite structure with (1 0 1) plane as the preferred orientation. The grain size of the pellets was increased with increasing concentration of vanadium. The atomic force microscopy shows a rough surface for all the pellets, we can see also that the surface roughness increases with increasing of doping concentration of 93–214 nm. Raman spectroscopy reveals a shift position in zinc oxide modes due to vanadium doping, the appearance of E 1 and E 2 modes showed that the wurtzite structure of ZnO is still maintained after doping of vanadium. [ABSTRACT FROM AUTHOR]

Alumina may display a complex polymorphism depending on the production method. Starting from Al-solution, their amorphous or crystalline structures as well as its phase are strongly determined by the precursor, temperature, pressure, pH, etc. However, starting from Al containing solids, there is a lack of information about the procedure to obtain a determined phase and concerning the influence of its surface finish on the morphological texture of the alumina growth. In this work, Fe22Cr5Al plates were subjected to mirror polishing and mechanical erosion. The fractal dimension determined from optical images was 2.084 for mirror polished samples and 2.472 for the eroded ones; these values give a comparative element for the starting surface finishing, because a higher fractal dimension value means an increasing surface roughness. Thereafter, both samples were oxidized at 900 °C, 24 h in air. By SEM, the polished-oxidized samples show a passivation layer formed by agglomeration of relative small particles, of around 400 nm; whereas the eroded-oxidized samples show whiskers with 100 nm thickness. The fractal dimension determined from SEM images was 2.511 for the polished-oxidized samples and 2.582 for the eroded-oxidized ones. EDXS analysis detects Al and O enrichment at the surface and XRD identifies the ? and a phases of alumina, for both kind of surface finish. Results demonstrate that the difference found in the oxide morphology is directly related to the surface finish before oxidation. This in turn is attributed to the difference in the surface defects density acting as nucleation centers for alumina whiskers. [ABSTRACT FROM AUTHOR]

The steam reforming of methane over Cu/Co6Al2 mixed oxides with different copper contents was studied. The Co6Al2 support was prepared via the hydrotalcite route. It was thermally stabilized at 500°C, impregnated with 5wt.%, 15wt.% or 25wt.% copper using copper (II) nitrate Cu(NO3)2·3H2O precursor and then calcined again at 500°C under an air flow. The impregnation of copper enhanced significantly the reactivity of the solids in the considered reaction. The 5Cu/Co6Al2 solid was the most reactive one, with a methane conversion of 96% at 650°C. The selectivities of H2 and CO2 were also better for the catalyst containing 5wt.% copper compared to higher copper loadings. The decrease in the catalytic reactivity with increasing the copper content was attributed to the formation of agglomerated and less reactive CuO species, which were detected by XRD and TPR analyses. [ABSTRACT FROM AUTHOR]

We report characterization of four porous ceramics, C1, C2, C3 and C4, obtained from four polyurethane foams E1, E2, E3 and E4, used as a matrix, and red slurries as reinforcement. The foams were studied with Scanning Electron Microscopy SEM, pore size was determined using the ASTM E1 12 [1], and the chemical composition of red clays was done by X ray diffraction (XRD) [2]. Barbotine of 1.5 g/cm3 density a particle size sieve intern 325 ASTM (45 mm), and a viscosity of 365.3 cP were used. Manufacturing process was by immersion of the foam in the barbotine for 24 hours, then it was subjected to a drying at room temperature for 48 hours and 12 hours in an oven with forced circulation; subsequently, firing took place in an electric muffle at a maximum temperature of 1000 °C for 4 hours. The percentage of porous ceramics was determined by absorption of water by using the NTC 4321-3 [3]. Mechanical resistance to bending was determined according the standard ISO 10545-4 [4] and the grain size by using the ASTM E1 12 [1]. Our the results show an inverse relationship between the density of the foam and the ceramics. The mechanical strength decreases as the porosity increases, and it increases with the grain size. We did not find a clear relationship between the shape and pore size in the foam and the shape and grain size of the ceramics. The properties of the foam used as matrix significantly influence the properties of ceramics obtained from them. The purpose of this paper is to contribute to a method in the manufacture and characterization of porous ceramics to be used at industrial-level processes. [ABSTRACT FROM AUTHOR]

The present work it is make a to review of the simplified methods of the X-ray diffraction peak profile analysis of as a powerful tool for the characterization of the structure of polycrystaline materials and to show an example of use of that methods. The considered methods are those of the traditional and modified Williamson- Hall and Warren-Averbach methods. The use of these methods for obtains stacking fault probability, dislocation contrast factors and crystallite size distribution is shown. The methods are applied to a Cu-5 wt.% Cr processed by means mechanical alloying and to a manganese steel obtained by means conventional melting and cold deformed in compression. [ABSTRACT FROM AUTHOR]

ZnSO4 ⋅ 3Zn(OH)2 ⋅ 4H2O(Zinc Sulfate Hidroxide Hidrate) films were obtained on glass substrates by SILAR method. It was employed a precursor solution of ZnSO4 and MnSO4 and water near boiling point complexed with 1 ml of NH4OH as a second solution. Films were treated on air at 300°C by 1 hour. Both films ZnSO4 ⋅ 3Zn(OH)2 ⋅ 4H2O as ZnO are important protective against zinc corrosion because they are passive films that give a longer duration to material, it is therefore relevant to study their response to temperature changes. For those reasons films were analyzed before and after thermal treatment to study the structural and morphological changes by X ray diffraction (XRD), Scanning electron microscopy (SEM) and Raman Microscopy techniques. It was found before thermal treatment by XRD the presence of ZnSO4 ⋅ 3Zn(OH)2 ⋅ 4H2O triclinic phase and after such treatment the ZnO hexagonal phase was evidenced. The morphology identified by SEM before thermal treatment was sheets formed by platelet like structure of micrometric size which changes after thermal treatment to a combination of those sheets with flowers like structure characteristic of ZnO hexagonal. By /it-Raman the hexagonal ZnO phase before thermal treatment as the triclinic ZnSO4 ⋅ 3Zn(OH)2 ⋅ 4H2O phase after thermal treatment were confirmed. One objective of this study was to obtain this protective corrosion material in a controlled manner by techiniques of low cost and high simplicity as Silar method. Which, even under temperture increases continue being protective corrosion although suffers phase changes because new phases have protective corrosive characteristics too. [ABSTRACT FROM AUTHOR]

Copyright of Visión Electrónica is the property of Fondo de Universidad Distrital Francisco Jose de Caldas and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Calcium phosphate powders were synthesized based on a wet chemical precipitation method at room temperature. A critical aging time of the precipitate is required in order to form a desired intermediate complex that permits a further transformation to apatite phase under appropriate thermal treatment. The processing parameters effect on apatite formation was systematically studied in terms of aging time and different condition of synthesis using Thermal Analysis, X-ray diffraction and Fourier transform infrared spectroscopy. The transformation of calcium phosphate deficient apatite (monetite and Ca2P2O7) obtained after one and two weeks of aging time into hydroxyapatite is completed when a heat treatment is applied at 600 °C under air. The HA nanocrystal sizes decrease with the increase of the aging periods, from 90 to 50 nm. The results show that by suitable tailoring of the processing parameters one can obtain calcium phosphate powders of desired dimensions. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we describe the preparation of a new aluminophosphate (AlPO-DACH) [C6 H18 N2Al4 P5.32O21.32] by hydrothermal method. The structure was characterized by the single-crystal X ray diffraction. This material crystallizes in the trigonal system, space group P-3c1, a=12.948Å, b=12.948Å, c=18.466Å; α=90°; β=90°; γ=120°.V=26811(16)Å3, Z=12, R:0.086 with 808 reflections. [Copyright &y& Elsevier]

The article presents an analysis of the mineral composition and physical attributes of ancient pottery artifacts excavated from Tamil Nadu, India. It explains that the pottery artifacts were analyzed using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and thermogravimentry/differential thermal analyzer (TG-DTA). Based on the results, the kaolinite mineral survived in the firing process and its decomposition is evidenced by endotherm between 500 to 650 centigrade.

Introduction: A problem to be solved by modern society is associated with development of biomaterials for prostheses to ensure the replacement of organs and body functions that have been damaged by accident or problems associated to increased life expectancy of population. Poliapatita® is a composite formed by hydroxyapatite (HAP-200), CaCO3 and polyvinyl acetate (POVIAc®). The aims of this work were the physico-chemical and termoanalytical characterization of the composite and the starting materials by means of different techniques: X-Ray Diffraction (DRX), Infrared Spectroscopy (FT-IR) and Differential Scanning Calorimetry (DSC). Material and Methods: The working interval used in FT-IR was 500 − 4000 cm-1 with a resolution of 4 cm-1. DRX analysis were accomplished employing the Kα Cu radiation, an angular range (2ϑ) between 20 and 60° and a scan rate of 0.10° angular 2ϑ/min. The temperature was varied from 20 −250 °C and uses a heating speed of 10 °C / min in the DSC analysis. Results and Discussion: The infrared spectrum of Poliapatita® showed that all the mixed signals correspond to the characteristic bands of the starting materials. Through the DRX characterization and the Hanawalt method analysis two crystalline phases were observed corresponding to HAP-200 and CaCO3. In the DSC analysis, the same three POVIAc® signals were observed but with shifts towards to higher temperature values on composite sample. Conclusion: The physico-chemical characterization allowed verifying that there not were any interaction between POVIAc® and the inorganic components. The DSC analysis showed a stabilization of the polymer on Poliapatita® because of an increasing of 70 °C on POVIAc® degradation temperature. [ABSTRACT FROM AUTHOR]

The article presents a study on the crystalline phases supported with titanium dioxide in red ceramic. The study uses X-ray diffraction to investigate the phase transformation anatase-rutile at different temperatures for supported titanium dioxide in red ceramic substrate prepared with kaolinitic clays. The result shows that the effect of the sintering temperature promotes the structural change of the phase more photoactive (anatase) for the less photoactive (rutile).

Highly weathered tropical soils tend to accumulate iron and aluminum oxy-hydroxides. Among the iron oxy-hydroxides found in the clay fraction, goethite (Gt) and hematite (Hm) are the most abundant and studied. A smaller number of investigations have been publish to identify and to quantify maghemite (Mh), a ferrimagnetic mineral present in the clay size fraction of the soils, mainly in those developed from mafic rocks. Maghemite, along with magnetite (Mt) is responsible for the spontaneous magnetic behavior of the soils. This mineralogical attribute can be easy measured, in soils and sediments by mass magnetic susceptibility (χLF), which magnitude is proportional to the concentration of ferrimagnetic minerals and it has been object of studies worldwide. The purpose of this research was to identify and quantify, by χLF, the ferrimagnetic minerals of 32 samples from B-horizons of Paraná state soils. The mineral species present in the iron oxides concentrated clay size fractions were identified and semiquantified by x-rays diffraction (XRD). In this fraction the most abundant minerals are Gt and Hm. Maghemite was detected in 31 samples by χLF and in only 17 samples by XRD. The χLF values ranged from 16 to 8.077x10-8m³ kg-1 in the fine earth; from 12 to 7.953x10-8m³ kg-1 in clay fraction and from 0 to 18.737x10-8m³ kg-1 in clay fraction, after concentration of the iron oxides. The Mh of the soils presented an average value of 62.728x10-8m³ kg-1 and their presence in the X-rays diffractograms was only observed in samples with χLF values above 1.000x10-8m³ kg-1. [ABSTRACT FROM AUTHOR]

Potassium niobate KNbO3 and some compounds of (K1-xNax)NbO3 (x = 0.3, 0.4, 0.6, 0.7) ceramics powders were successfully prepared by the solid-state reaction method using a non-stoichiometric mixture of starting materials. A possible formation of these phases was proposed based on the experimental results. All of the prepared compounds were characterized using the X-ray diffraction method, and grain size has been calculated using SEM images, and their stoichiometry was obtained from the EDAX results. [ABSTRACT FROM AUTHOR]

It was described the Li atoms incorporation in MoO3 thin films. Samples were prepared by evaporation using a CO2 Laser working at continuum wave mode. There were used targets with 1%, 2% and 5% (Li ions/Total cations). Samples were characterized with X ray Diffraction (XRD). XRD spectra showed that samples prepared with substrate temperatures lower than 200 \C were amorphous, for higer temperatures, samples grow whith a mixture of the a and b phases of LiMoO3 and Li2MoO4 with orientation through (100), (111) y (012) planes. [ABSTRACT FROM AUTHOR]

This work presents the use of the technique of current pulsant inverse, pulse direct current and direct current for electrodeposition thin films Cu/Cd in double-layer shape on Zamak substrate. The influence of the different variables was studied involved in each one of the processes: voltage and time of deposition (VHigh and tHigh), voltage and time of breakup (VLow and tLow) and the load cycle (θ=tHigh/tHigh+tLow), obtaining as answer the monitory of the average anodic (ILow) and cathodic (IHigh) in function of the time anodic (tLow) and cathodic (tHigh), respectively. The electrodeposits of Cu/Cd was characterized by means ray x diffraction being observed the structure and composition in each one of the films obtained. It was observed that the control pulsant of the voltage during the deposit to influence in the composition of the electrodeposits. [ABSTRACT FROM AUTHOR]

The rotor stoichiometry of F-ATPases has been revealed by the combined approaches of X-ray diffraction (XRD), electron crystallography, and atomic force microscopy (AFM). XRD showed the rotor from the yeast mitochondrial F-ATPase to contain 10 subunits. AFM was used to visualize the tetradecameric chloroplast rotors, and electron crystallography and AFM together revealed the rotors from Ilyobacter tartaricus to be composed of 11 subunits. While biochemical methods had determined an approximate stoichiometric value, precise measurements and new insights into a species-dependent rotor stoichiometry became available by applying the three structural tools together. The structures of AQP1, a water channel, and GlpF, a glycerol channel, were determined by electron crystallography and XRD. The combination of both of these structural tools with molecular dynamics simulations gave a differentiated description of the mechanisms determining the selectivity of water and glycerol channels. This illustrates that the combination of different methods in structural biology reveals more than each method alone.Key words: AQP1, GlpF, F-ATPase, XRD, electron crystallography, AFM.La stoechiométrie des F-ATPases a été déterminée par des approches combinées de cristallographie par diffraction de rayons X (DRX), cristallographie électronique et microscopie des forces atomiques (MFA). La DRX a montré que le rotor de l'ATPase F mitochondriale de la levure est constitué de 10 sous-unités. La MFA a été utilisée pour visualiser les rotors tétradécamériques des chloroplastes et l'association de la cristallographie électronique et de la MFA a permis de montrer que les rotors de Ilyobacter tartaricus sont constitués de 11 sous-unités. Alors qu'une valeur stoechiométrique approximative avait été déterminée par des méthodes biochimiques, des mesures précises et de nouvelles données concernant la stoechiométrie des rotors selon les espèces ont été obtenues en utilisant ces trois outils ensemble. Les structure de AQP1, un canal de l'eau, et de GlpF, un canal du glycérol, ont été déterminées par cristallographie électronique et DRX. La combinaison de ces deux outils d'études structurales avec des simulations de dynamique moléculaire a permis d'obtenir une description des différences qui distinguent les mécanismes déterminant la sélectivité du canal de l'eau et la sélectivité du canal du glycérol. Cela démontre que la combinaison de différentes méthodes de biologie structurale révèle plus de choses que chacune de ces méthodes seule.Mots clés : AQP1, G1pF, F-ATPase, diffraction de rayons X, DRX, crystallographie électronique, microscopie des force atomiques, MFA.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Two groups of samples with compositions Fe100-xNix, with 22.5≤x≤40, were elaborated by elementary mixing of powders and later sintering at 750° C by 3 hours and 1000° C by 1 hour,. For their characterization it were used X-ray diffraction and Mössbauer spectrometry. From the spectra fit the coexistence of the BCC and FCC phases was observed in whole the range of composition studied. The lattice parameters are lightly different from the observed for the elementary powders, indicating dif- fusion of Fe atoms into the Ni lattice and of Ni atoms into the Fe lattice. This effect is bigger in samples sinterized at high temperatures. The fits of the Mössbauer spectra were realized by means of the use of two hyperfine field distributions, each one related to the structural phases found. The hyperfine field distribution for 750 °C are centred at fields about 33T for the BCC component and at 30T for the FCC component. In the case of samples sinterized at 1000°C the average field of the BCC component continues around 33T but the average field of the FCC component ranges around 27T, explainded as due to the contribution of low magnetic fields arounds 10T, this is a typical behavior of Invar alloys. [ABSTRACT FROM AUTHOR]

Structural and morphologic analysis obtained from ITO thin films (indium tin oxide, In2O3:Sn) prepared by the Sol -- gel method, grown on glass substrates, are presented. The films obtained with different number of layers and concentration of glycerine, used as agglutinative material, were characterized by Scanning electron microscopy (SEM) and X-rays diffraction (XRD). The analyses of microscopy show the homogeneity and the grain size (59 - 192 nm) on the surface before and after annealing, as well as the cracking of the film in certain regions due to the changes of the drying and calcination temperature and the composition of the precursor solutions. By means of XRD the cubic structure with a lattice parameter 10.116 Å and its polycrystalline character was determined. Finally, a comparison is done with the structure In2O3. [ABSTRACT FROM AUTHOR]

The influence of type of steel and immersion time on the formation of magnetite in corrosion processes was investigated. For that purpose, weathering (WS) and low carbon steels (CS) were submitted to total immersion tests in a 0.2M NaCl solution for three different immersion times. The rusts which stay bounded to the metal, called adherent rusts (AR), as well as the rusts which is loosely bounded and suspended in the solutions, called non-adherent rusts (NAR), were studied by several techniques and the characteristics of the magnetite were determined. In this way measurements of X-ray diffraction (XRD), diffuse reflectance infrared Fourier transform (DRIFT), Raman micro-spectroscopy (μ-Raman) and Mössbauer spectrometry (MS) were carried out. Magnetite was detected in all AR and NAR of CS after 14 days of immersion, but detected neither in AR nor in NAR of WS. Differences in stoichiometry, lattice parameter and vibrational characteristics were found. A possible mechanism for inhibition of magnetite formation on WS is discussed. [ABSTRACT FROM AUTHOR]

Mineral ilmenite presents in black beach sands has been high- energy milling at room temperature in air by 10, 20 and 40 hours in attritor mill, and characterised by X-ray diffraction and Mössbauer Spectroscopy. Three ilmenite phases were founded with both techniques. The formation of new phases: gieckelite; suessite; hisingerite and dolomite and a high degree of amorphization with the milling time were detected by XRD. [ABSTRACT FROM AUTHOR]