X-ray diffraction from Al powder using energy dispersive technique

Using the energy dispersive x ...ray diffraction (EDXD) technique, the room temperature diffraction pattern of Al powder was obtained at diffraction angles ~ 30° and 50°. From the small angle diffraction pattern the average relative intensities (IR) of the (111), (200), and (220) lines were measured to be equal to 100, 62, and 32 respectively. From the large diffraction angle IR for the (220), (311+222), (400), (331+420), and (422) lines were measured to be 100,201,17,90, and 19.5 respectively. The diffraction pattern at those two angles were obtained at several higher temperatures to measure the change in the intensities of the Al lines. From the intensity changes the increase of the Debye- Waller temperature factor, i.e ~B(T), with respect to the value at room temperature was determined to be 0.6+0.1 at 250°C, 1.10+0.15 at 350°C, 1.45+0.20 at 450°C, and 2.20±0.35 at 550°C.

The effects of gramicidin on the structure of phospholipid assemblies /

Gramicidin is an antibiotic peptide that can be incorporated into the monolayers of cell membranes. Dimerization through hydrogen bonding between gramicidin monomers in opposing leaflets of the membrane results in the formation of an iontophoretic channel. Surrounding phospholipids, with various associated mechanical properties, have been shown to influence the gating properties of this channel. Conversely, gramicidin incorporation has been shown to affect the structure of spontaneously formed lipid assemblies. Using small-angle x-ray diffraction and model systems composed of phospholipids and gramicidin, the physical effects incurred by gramicidin incorporation were measured. The reverse hexagonal (H^) phase composed of dioleoylphosphatidylethanolamine (DOPE) monolayers decreased in lattice dimension with increasing incorporation of gramicidin. This indicated that gramicidin was adding negative curvature to the monolayers. In this system, gramicidin was measured to have an apparent intrinsic radius of curvature (Rop*™") of -7. 1 A. The addition of up to 4 mol% gramicidin in mixtures with DOPE did not result in the monolayers becoming stiffer, as indicated by unaltered bending moduli for each composition. Dioleoylphosphatidylcholine (DOPC) alone forms the lamellar (LJ phase when hydrated, but undergoes a transition into the H^ phase when mixed with gramicidin. The lattice repeat dimension decreases systematically with increased gramicidin content. Again, this indicated that gramicidin was adding negative curvature to the monolayers. At 12 mol% gramicidin in mixtures with DOPC, the apparent radius of intrinsic curvature of gramicidin (Rop*"^) was measured to be -7.4 A. This mixture formed monolayers that were very resistant to bending under osmotic pressure, with a measured bending modulus of 1 15 kT. The measurements made in this study demonstrate that peptides are able to modulate the spontaneous curvature and other mechanical properties of phospholipid assemblies.

Tuning mesoporous molecular sieve SBA-15 for the immobilization of α-amylase

The present work describes the immobilization of α-amylase over well ordered mesoporous molecular sieve SBA-15 with different pore diameters synthesized by post synthesis treatment (PST) hydrothermally after reaction at 40°C. The materials were characterized by N 2 adsorption–desorption studies, small angle X-ray diffraction, scanning electron microscopy and high resolution transmission electron microscopy. Since α-amylase obtained from Bacillus subtilis has dimensions of 35 × 40 × 70 Å it is expected that the protein have access to the pore of SBA-15 (PST-120°C) with diameter 74 Å. The pore dimension is appropriate to prevent considerable leaching. The rate of adsorption of the enzyme on silica of various pore sizes revealed the influence of morphology, pore diameter, pore volume and pH.

The expected imprint of flux rope geometry on suprathermal electrons in magnetic clouds

Magnetic clouds are a subset of interplanetary coronal mass ejections characterized by a smooth rotation in the magnetic field direction, which is interpreted as a signature of a magnetic flux rope. Suprathermal electron observations indicate that one or both ends of a magnetic cloud typically remain connected to the Sun as it moves out through the heliosphere. With distance from the axis of the flux rope, out toward its edge, the magnetic field winds more tightly about the axis and electrons must traverse longer magnetic field lines to reach the same heliocentric distance. This increased time of flight allows greater pitch-angle scattering to occur, meaning suprathermal electron pitch-angle distributions should be systematically broader at the edges of the flux rope than at the axis. We model this effect with an analytical magnetic flux rope model and a numerical scheme for suprathermal electron pitch-angle scattering and find that the signature of a magnetic flux rope should be observable with the typical pitch-angle resolution of suprathermal electron data provided ACE's SWEPAM instrument. Evidence of this signature in the observations, however, is weak, possibly because reconnection of magnetic fields within the flux rope acts to intermix flux tubes.

Whistler mode wave growth and propagation in the prenoon magnetosphere

Pitch-angle scattering of electrons can limit the stably trapped particle flux in the magnetosphere and precipitate energetic electrons into the ionosphere. Whistler-mode waves generated by a temperature anisotropy can mediate this pitch-angle scattering over a wide range of radial distances and latitudes, but in order to correctly predict the phase-space diffusion, it is important to characterise the whistler-mode wave distributions that result from the instability. We use previously-published observations of number density, pitch-angle anisotropy and phase space density to model the plasma in the quiet pre-noon magnetosphere (defined as periods when AE<100nT). We investigate the global propagation and growth of whistler-mode waves by studying millions of growing ray paths and demonstrate that the wave distribution at any one location is a superposition of many waves at different points along their trajectories and with different histories. We show that for observed electron plasma properties, very few raypaths undergo magnetospheric reflection, most rays grow and decay within 30 degrees of the magnetic equator. The frequency range of the wave distribution at large L can be adequately described by the solutions of the local dispersion relation, but the range of wavenormal angle is different. The wave distribution is asymmetric with respect to the wavenormal angle. The numerical results suggest that it is important to determine the variation of magnetospheric parameters as a function of latitude, as well as local time and L-shell.

Ultralow-frequency modulation of whistler-mode wave growth

Measurements from ground-based magnetometers and riometers at auroral latitudes have demonstrated that energetic (~30-300keV) electron precipitation can be modulated in the presence of magnetic field oscillations at ultra-low frequencies. It has previously been proposed that an ultra-low frequency (ULF) wave would modulate field and plasma properties near the equatorial plane, thus modifying the growth rates of whistler-mode waves. In turn, the resulting whistler-mode waves would mediate the pitch-angle scattering of electrons resulting in ionospheric precipitation. In this paper, we investigate this hypothesis by quantifying the changes to the linear growth rate expected due to a slow change in the local magnetic field strength for parameters typical of the equatorial region around 6.6RE radial distance. To constrain our study, we determine the largest possible ULF wave amplitudes from measurements of the magnetic field at geosynchronous orbit. Using nearly ten years of observations from two satellites, we demonstrate that the variation in magnetic field strength due to oscillations at 2mHz does not exceed ±10% of the background field. Modifications to the plasma density and temperature anisotropy are estimated using idealised models. For low temperature anisotropy, there is little change in the whistler-mode growth rates even for the largest ULF wave amplitude. Only for large temperature anisotropies can whistler-mode growth rates be modulated sufficiently to account for the changes in electron precipitation measured by riometers at auroral latitudes.

Adsorption of Pb(2+), Cu(2+) and Cd(2+) in FDU-1 silica and FDU-1 silica modified with humic acid

Ordered mesoporous silica with cubic structure, type FDU-1, was synthesized under strong acid media using B-50-6600 poly(ethylene oxide)-poly(butilene oxide)-poly(ethylene oxide) triblock copolymer (EO(39)BO(47)EO(39)) and tetraethyl orthosilicate (TEOS). Humic acid (HA) was modified to the synthesis process at a concentration of 1.5 mmol per gram of SiO(2). Thermogravimetry, small angle X-ray diffraction, nitrogen adsorption and high resolution transmission electron microscopy were used to characterize the samples. The pristine FDU-1 and FDU-1 with incorporated 1.5 mmol of HA were tested for adsorption of Pb(2+), Cu(2+) and Cd(2+) in aqueous solution. Incorporation of humic acid into the FDU-1 silica afforded an adsorbent with strong affinity for Cd(2+), Cu(2+) and Pb(2+) from single ion solutions. Adsorption of Cu(2+) was significantly enhanced after incorporation of humic acid, a fact that can be explained by the formation of complexes with carboxylic and phenolic groups at low concentrations of the metal cation. The results demonstrated the potential applicability of FDU-1 with incorporated HA in the removal of low concentrations of heavy metal cations from aqueous solution, such as wastewaters, after usual precipitation of metal hydroxides in alkaline medium and proper pH conditioning in the range between 6 and 7. (C) 2007 Elsevier Inc. All rights reserved.

High sensitivity fiber optic angular displacement sensor and its application for detection of ultrasound

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Controlling the growth of zirconia needles precursor from a liquid crystal template

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo de propriedades elétricas em sistemas orgânicos e inorgânicos correlacionados

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Aspergillus niger beta-Glucosidase Has a Cellulase-like Tadpole Molecular Shape INSIGHTS INTO GLYCOSIDE HYDROLASE FAMILY 3 (GH3) beta-GLUCOSIDASE STRUCTURE AND FUNCTION

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Processo de esmerilhamento, polimento e caracterização de um Shear Plate

Shearplate is an optical glass plate having two flat surfaces and a small angle between them. The use of a high quality shear plate is essential to implement shear interferometric technique . The shear interferometry is a technique used to evaluate the light beam collimation. In order to guarantee the shearplate quality , the complete manufacturing process must be thoroughly monitored. In the manufacturing process, the first step consisted of the glass selection. The selected glass has been submitted to the process of cutting, gluing, chamfering, grinding and polishing. Each phase has been strictly monitored. The quality of the final result depends extremely on an appropriate starting condition, which arises from the grinding process, as the polishing process only recovers the brightness of the part, acting on a small scale on the wearing off of the part, as well as not changing the structured obtained in the grinding process. Respecting all stages of the manufacturing process, the quality of the part has evolved to a good result. The best result obtained showed PV distance of 162 nm, slightly less than λ / 4. This result is significant because the dimensions of the piece with respect to the dimensions of the polisher what interferes directly in the results. The closer are the dimensions of piece and the dimensions of the polisher, the greater the difficulty in controlling the propagation of errors

Construção e calibração de um inclinômetro para uso em tratores agrícolas como instrumento de segurança

The tractors are the main potency source, for the traction of tillage equipments and their use are increasing more and more in Brazilian agriculture. In spite of the great technological progress the increase of the number of agricultural tractors brought positive aspects and some negative, among these last ones it stands out the appearance of a new source of work accidents, which importance is given by the physical damages caused to the operator. Therefore the objective of this work was to project and develop an inclinometer, which indicates the inclination of the land, as safety sensor for agricultural tractors to avoid lateral hollovers, through a resonant sign, for the operator and the machine preservation. The built and evaluated inclinometer showed to be efficient for inclination indication of different areas during field operations with agricultural tractors, small angle oscillation and enough answer time to help operators to take decisions in imminence situation of lateral machine hollovers.

Cosmetic Orbital Inferomedial Decompression: Quantifying the Risk of Diplopia Associated With Extraocular Muscle Dimensions

Purpose: To quantify the risk of new diplopia in inferomedial orbital decompression performed for cosmetic reasons. Methods: Retrospective analysis of 114 patients with Graves orbitopathy who underwent an inferomedial orbital decompression. No patient had diplopia in any of the gaze positions or optic neuropathy. A single coronal slice 9 mm posterior to the lateral orbital rim was employed to quantify the muscular index of the extraocular recti and of the superior complex. A control group of 56 patients imaged for other reasons were also measured. After surgery the oculomotor status of all patients who complained of diplopia and of 51 patients free of diplopia was measured with the prism and cover test in the primary and secondary gaze positions. Results: The rate of new-onset diplopia was 14.0% (16 patients). Eye deviations were confirmed in 14 patients. Of these, 10 had significant strabismus that warranted surgical or prism treatment. Most patients had esotropia associated with small vertical deviations. The size of the medial and inferior recti was significantly associated with the development of diplopia. The estimated odds for the appearance of diplopia in patients with muscle enlargement was 12.76 (medial rectus) and 5.21 (inferior rectus). Small-angle deviations were also detected in 27.4% of patients who did not experience diplopia. Conclusions: Medial and inferior recti enlargement is a strong predictor of new-onset diplopia. A large number of patients who do not report diplopia also present with small-angle deviations. (Ophthal Plast Reconstr Surg 2012;28:204-207)

Nucleation studies on graphics processing units

Ein System in einem metastabilen Zustand muss eine bestimmte Barriere in derrnfreien Energie überwinden um einen Tropfen der stabilen Phase zu formen.rnHerkömmliche Untersuchungen nehmen hierbei kugelförmige Tropfen an. Inrnanisotropen Systemen (wie z.B. Kristallen) ist diese Annahme aber nicht ange-rnbracht. Bei tiefen Temperaturen wirkt sich die Anisotropie des Systems starkrnauf die freie Energie ihrer Oberfläche aus. Diese Wirkung wird oberhalb derrnAufrauungstemperatur T R schwächer. Das Ising-Modell ist ein einfaches Mo-rndell, welches eine solche Anisotropie aufweist. Wir führen großangelegte Sim-rnulationen durch, um die Effekte, die mit einer endlichen Simulationsbox ein-rnhergehen, sowie statistische Ungenauigkeiten möglichst klein zu halten. DasrnAusmaß der Simulationen die benötigt werden um sinnvolle Ergebnisse zu pro-rnduzieren, erfordert die Entwicklung eines skalierbaren Simulationsprogrammsrnfür das Ising-Modell, welcher auf verschiedenen parallelen Architekturen (z.B.rnGrafikkarten) verwendet werden kann. Plattformunabhängigkeit wird durch ab-rnstrakte Schnittstellen erreicht, welche plattformspezifische Implementierungs-rndetails verstecken. Wir benutzen eine Systemgeometrie die es erlaubt eine Ober-rnfläche mit einem variablen Winkel zur Kristallebene zu untersuchen. Die Ober-rnfläche ist in Kontakt mit einer harten Wand, wobei der Kontaktwinkel Θ durchrnein Oberflächenfeld eingestellt werden kann. Wir leiten eine Differenzialglei-rnchung ab, welche das Verhalten der freien Energie der Oberfläche in einemrnanisotropen System beschreibt. Kombiniert mit thermodynamischer Integrationrnkann die Gleichung benutzt werden, um die anisotrope Oberflächenspannungrnüber einen großen Winkelbereich zu integrieren. Vergleiche mit früheren Mes-rnsungen in anderen Geometrien und anderen Methoden zeigen hohe Überein-rnstimung und Genauigkeit, welche vor allem durch die im Vergleich zu früherenrnMessungen wesentlich größeren Simulationsdomänen erreicht wird. Die Temper-rnaturabhängigkeit der Oberflächensteifheit κ wird oberhalb von T R durch diernKrümmung der freien Energie der Oberfläche für kleine Winkel gemessen. DiesernMessung lässt sich mit Simulationsergebnissen in der Literatur vergleichen undrnhat bessere Übereinstimmung mit theoretischen Voraussagen über das Skalen-rnverhalten von κ. Darüber hinaus entwickeln wir ein Tieftemperatur-Modell fürrndas Verhalten um Θ = 90 Grad weit unterhalb von T R. Der Winkel bleibt bis zu einemrnkritischen Feld H C quasi null; oberhalb des kritischen Feldes steigt der Winkelrnrapide an. H C wird mit der freien Energie einer Stufe in Verbindung gebracht,rnwas es ermöglicht, das kritische Verhalten dieser Größe zu analysieren. Die harternWand muss in die Analyse einbezogen werden. Durch den Vergleich freier En-rnergien bei geschickt gewählten Systemgrößen ist es möglich, den Beitrag derrnKontaktlinie zur freien Energie in Abhängigkeit von Θ zu messen. Diese Anal-rnyse wird bei verschiedenen Temperaturen durchgeführt. Im letzten Kapitel wirdrneine 2D Fluiddynamik Simulation für Grafikkarten parallelisiert, welche u. a.rnbenutzt werden kann um die Dynamik der Atmosphäre zu simulieren. Wir im-rnplementieren einen parallelen Evolution Galerkin Operator und erreichen