bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibitors for Reducing Hydrogen Ingress During Corrosion of Zirconium Alloys
Authors: Elmoselhi MB , Donner A
Published: April 2008

Zirconium alloys, used in manufacturing nuclear core components, particularly fuel cladding (in most reactor types) and pressure tubes in CANDU® (Canada Deuterium Uranium) reactors, are usually subject to aqueous corrosion and hydrogen uptake during service. The build up of hydrogen concentration during operation can be a life-limiting factor for these components. In order to slow down the rate of hydrogen uptake and to prolong the operating life of these critical reactor components, a remedial action was targeted. A comprehensive experimental program has been carried out to identify potential inhibiting agents to be introduced into the environment of the corrosion process. The inhibiting agents were expected to intervene in the corrosion reactions to reduce the hydrogen uptake rate. Screening experiments were conducted in short-term exposures (up to 30 days) of coupons from several zirconium alloys, such as Zircaloy-2, Zircaloy-4 and Zr-2.5 weight % Nb, in high temperature (340°C) aqueous out-reactor environments simulating the CANDU heat transport coolant with various chemical compound additives. Several additives of nitrogen-containing compounds appeared to reduce hydrogen ingress significantly; up to 90 % reduction was observed. The beneficial effect of the presence of nitrogen on hydrogen uptake in these exposures might be related to its role in the production of ammonia from hydrogen liberated by the zirconium corrosion reactions. The ammonia generation mechanism has been proposed in the Ceramics literature as a means of increasing the yield of cubic zirconia during the hydrothermal oxidation of Zr in the presence of calcium nitrate. The formation of ammonia is associated with a significant reduction in the hydrogen available for pickup by the alloy. This hypothesis was confirmed in our experiments by the detection of ammonia in the post-exposure solutions. For all tested solutions with nitrogen-containing additives, ammonia was detected in the post-exposure solutions, while no ammonia was found in the post-exposure control solution or other solutions with non-nitrogen additives such as boric acid. Results from post-exposure analyses, oxide characterization, and a preliminary investigation into radiolysis implications are presented.
Effect of Fabrication Variables on Irradiation Response of Crack Growth Resistance of Zr-2.5Nb
Authors: Coleman CE , Theaker JR , Kidd KV
Published: April 2008

Specimens of pressure tubes made from Zr-2.5Nb by various fabrication routes were irradiated in research reactors to evaluate the response of their fracture toughness (represented by crack growth resistance, dJ/da) at 250°C to irradiation by fast neutrons (E > 1 MeV). The reference route consists of melting Kroll sponge and some recycled material, primary hot-working, extrusion at 815°C, and cold-working 27 %. Tubes made from ingots that were melted four times (quadruple melting) are initially tougher than tubes made from ingots that have been melted twice (double melting), and after irradiation the former retain close to 50 % of their original crack growth resistance while the latter retain less than 30 % of theirs. The high toughness and its retention in the quadruple melted material are attributed to low concentrations of chlorine. Tubes made from electrolytic powder contain fluorine rather than chlorine. Fluorine is less damaging than chlorine. Crack growth resistance and its retention with irradiation of tubes made from electrolytic powder are intermediate between those of tubes made from quadruple and double melted sponge. Lowering the amount of cold-work is beneficial, and the toughness of tubes made with less than 27 % cold-work correlates well with strength, both before and after irradiation. Lowering the extrusion temperature produces strong, tough tubes, but these tubes lose much of their crack growth resistance with irradiation. This loss in toughness is not associated with material chemistry but with a high sensitivity to strength.
Influence of Long Service Exposures on the Thermal-Mechanical Behavior of Zy-4 and M5™ Alloys in LOCA Conditions
Authors: Portier L , Bredel T , Brachet J-C , Maillot V , Mardon J-P , Lesbros A
Published: April 2008

The main objective of this paper is to describe the effects of a long service exposure of the PWR fuel cladding tubes on their thermal-mechanical properties during and after a hypothetical LOCA transient. Within this prospect, specific studies have been performed: on one hand, thermal ramp tests under uniaxial stress loading on as-received, pre-hydrided and irradiated samples of Zy-4 and M5™, and on the other hand, mechanical tests after high temperature oxidation and quench on as-received and pre- hydrided Zy-4 and M5™. The main conclusions are: (1) In service, hydrogen pick-up impacts the thermal ramp behavior under uniaxial stress loading of cladding tubes upon the first phase of LOCA transient, and the effect of the irradiation defects can be ignored for the conditions tested. (2) As-received Zy-4 and M5™ achieve comparable post-quench mechanical behavior at 1000, 1100, and 1200°C for representative times of LOCA transient (1800 s). (3) Oxygen has the most important effect in embrittlement of as-received Zr alloys at 1100 and 1200°C. (4) Hydriding has no effect on the oxidation kinetics at 1200°C, but after quenching the hydrided materials become brittle at a lower weight gain than as-received materials; this embrittlement is due both to an intrinsic hydrogen-embrittlement effect and to the oxygen content increase resulting from the effect of hydrogen on its solubility in prior-Beta phase.
Effect of Aging Treatments on the Tensile Properties of Ti-35Nb-7Zr-5Ta-(0.06-0.7)O Alloys
Authors: Qazi JI , Tsakiris V , Marquardt B , Rack HJ
Published: April 2008

Ti-35Nb-7Zr-5Ta rods containing 0.06, 0.46, and 0.68 wt.% oxygen were produced by vacuum arc melting and forging. These were solution treated (ST) and aged in the temperature range of 427-593°C for 8 h followed by air cooling. Increasing oxygen content increased the ST yield strength (YS) from 530 to 1081 MPa. The largest increase in YS, 630MPa, in Ti-35Nb-7Zr-5Ta-0.06O observed after aging at 427°C was associated with ω phase precipitation. While the largest increases in YS, (1060 and 1288 MPa, in Ti-35Nb-7Zr-5Ta-0.46/0.68O) observed after aging at 482°C were associated with fine and somewhat inhomogeneous precipitation of the α phase, the tensile elongation remained above 8°. Aging at 538 or 593°C led to an increase in the inhomogeneity in α phase precipitation in Ti-35Nb-7Zr-5Ta-0.46/0.68O, precipitate free zones clearly being observed along with prior β grain boundaries, which served as preferred paths for early crack propagation and decreased tensile ductility.
Effects of Proton Irradiation on Reactor Pressure Vessel Steel and Its Model Alloys
Authors: Shibamoto H , Kimura A , Hasegawa M , Matsui H , Yamaguchi S
Published: April 2008

Effects of proton irradiation on the reactor pressure vessel steel (RPVS), A533B cl. 1 have been investigated by means of positron lifetime and Vickers hardness measurement in comparison with those of the iron-copper model alloys. The specimens were irradiated with 1 MeV proton up to a fluence of 3 × 1017 ions/cm2 (0.2 dpa, displacement per atom, at a peak) at temperature below 80°C. The recovery behavior of the irradiation effects was also investigated during isochronal annealing for 30 min with a 25°C step from 100°C to 650°C. By positron annihilation technique, it was recognized that microvoids, which consist of about 5 vacancies with the number density of the order of 1016 /cm3, were formed by the irradiation. The number of microvoids decreased after a low temperature annealing and completely annihilated at 250°C, although irradiation hardening still remained. A large portion of the hardening recovered by the annealing up to 300°C and almost annealed out at 450°C. Irradiation response and its recovery behavior of A533B RPVS were discussed compared to the result of Fe-based model alloys.
Tribology of Hydraulic Systems: Hydrodynamic Effects of Surface Roughness
Authors: Tønder K
Published: April 2008

The paper deals with the tribology of surface roughness effects in rapidly moving hydraulic units, such as pumps, motors and seals. The emphasis is on laminar flow, turbulence effects being only briefly discussed. The analysis is based on lubrication theory that was originally developed for bearings in non-hydraulic equipment. However, the established results are readily adoptable to a hydraulic environment. The effects may be quasi-static or dynamic. It is shown that surface roughness may affect the operation of hydraulic units negatively or positively, depending on the actual conditions, resulting in a need for optimisation and compromise, but also in the possibility to tailor surfaces for optimal operation. Finally, for situations when an undesirable roughness structure on the surfaces is unavoidable, the paper presents methods by which the surface finish (roughness amplitude) necessary for safe operation may be determined.
Modeling Abrasive Wear of Homogeneous and Heterogeneous Materials
Authors: Elalem K , Li DY , Anderson MJ , Chiovelli S
Published: April 2008

A micro-scale dynamic approach was recently proposed to simulate wear of materials. The model was developed based on fundamental physical laws without employing empirical equations or tribological rules. In this model, a material system is discretized and represented using a discrete lattice. Each lattice site represents a small volume of the material. During wear, a lattice site may move under the influence of external force and the interaction between the site and its adjacent sites, which depends on the mechanical properties of the material, such as the elastic modulus, yield strength and work-hardening. The movement and trajectory of lattice sites during wear were determined using Newton's law of motion. A bond can be broken when the total accumulated plastic strain exceeds the fracture strain. A site or a cluster of sites is worn away if all bonds connecting the site or the cluster to its neighbors are broken. The model can provide information on the strain distribution in a contact region, consistent with finite element analysis. This model was applied to single-phase and composite materials abraded under dry sand/rubber wheel abrasion testing condition. Good agreement between the modeling and experiments was found.
Failure Analysis of the Hydraulic Drive System in a Storm Surge Barrier
Authors: Fluks M
Published: April 2008

In 1997 the last part of the extensive “Delta Works” in the Netherlands was completed and commissioned. This involved the construction of a storm surge barrier in the most densely navigated waterway of Holland, connecting the harbor of Rotterdam with the North Sea.

Due to the high risks involved when the barrier fails in its operation, a very low failure probability is required : 1×10-3 for the complete barrier system. This however resulted in much lower values for the numerous subsystems; in particular for the hydraulic drive and control system a failure probability of less than 1 × 10-6 is required for each operation.

For evaluation and calculation of the failure probability it was essential to have a good understanding of and consensus with the customer about a) the whole process and requirements in the different phases of the operational cycle, and b) the criteria which determine when the system is considered to fail.

Different analyses were performed to find the critical items in the system, and some adaptations (e.g. redundancy of certain components) and more detailed analysis of some parts of the system was necessary to obtain the required contract value for the failure probability.

Also it became necessary to perform a monthly inspection and check the drive and control system by means of a semi-automated procedure.

Several aspects of the failure analysis of the hydraulic system are discussed in this paper.
Advanced Strategies for the Monitoring and Control of Water Contamination in Oil Hydraulic Fluids
Authors: Troyer DD
Published: April 2008

Water contamination, the scourge of hydraulic oil, increases wear, promotes cavitation, depletes additives, degrades lubricant base-stock and enables microorganism growth. This paper explores the various ways in which water degrades hydraulic system reliability and suggests a program of oil analysis that will reveal to the diagnostician the nature and cause of the water ingress. This paper emphasizes the art of simultaneously interpreting multiple oil and wear debris analysis parameters to gain an understanding about the nature and severity of an incident of water contamination.
Fundamental Hydraulic Wear Processes
Authors: Liang H , Mizuno K , Totten GE , Bishop RJ , Lemberger S
Published: April 2008

To effectively perform root cause analysis of hydraulic wear problems and system failures, it is vital that the fundamental wear processes be correctly recognized and understood. In this paper, fundamental potential pump wear problems will be illustrated pictorially and the mechanisms of these processes will be discussed. Some of the wear processes to be discussed include: abrasion, adhesion, cavitation, rolling contact fatigue, corrosion, and lubrication failure. It is expected that this discussion will provide a basic background to facilitate understanding of the more complex wear processes to be discussed during this conference.
Hydraulic Valve Problems Caused by Oil Oxidation Products
Authors: Sasaki A
Published: April 2008

Modern hydraulic systems are sophisticated with proportional valves and servo valves. As they are sensitive to oil contamination, contamination control is imperative. The conventional practices of contamination control have focused on particulate contaminants but have paid less attention to oil oxidation products. In order to protect sophisticated hydraulic components, fine pore filters have been used.

As both oil and filter materials are dielectric, friction between them generates static electricity. Accumulated static electricity causes spark discharges and damages oils. Therefore hydraulic valve problems have not been solved yet, even though the conventional contamination control is implemented.

This paper discusses the mechanism of hydraulic valve lock due to oil oxidation products and the synergy effects of oil oxidation products and particulate contaminants for valve failures and verifies that the findings of the experiment can explain the hydraulic valve problems in the fields.
Ultrasonic Spectroscopy of Developmental Composite Rotors
Authors: Harmon LM , Baaklini GY
Published: April 2008

Multilayered composite materials are being studied extensively for implementation in flywheel systems for the International Space Station (ISS). Rotor standard sections have been developed to determine damage tolerance levels of the multilayered composite materials in these flywheel systems. Four such rotor sections with simulated delaminations, foreign material inserts, and notches were investigated with a recently developed ultrasonic spectroscopy technique. The ultrasonic system employs a continuous swept sine waveform and performs an FFT on the frequency spectrum. In addition, the system is capable of equalizing the amount of energy at each frequency. Equalization of the frequency spectrum, along with interpretation of the second FFT aids in the evaluation of the spectrum resonance spacing, or fundamental frequency. The ultrasonic responses from defect free regions of the multilayered rotor sections are compared with responses from regions with simulated delaminations, foreign material inserts, and notches to establish the potential of this nondestructive evaluation (NDE) method for the evaluation of flywheel rotor systems.
A Theoretical Study Of The Tensile Test For Highly Anisotropic Composite Materials
Authors: Lévesque M , Gilchrist MD , Fisa B
Published: April 2008

The stress field in a tabbed straight-sided tensile test specimen has been studied theoretically and experimentally. It is shown that the stress field has to be studied at every point in the specimen. It is also shown that the tab should be made as thick as possible and the clamping force set as large as possible in order to minimize the intensity of the stress field in the specimen. The tab's Young's modulus in the test direction is the elastic constant having the largest influence on the stress field in the specimen. However, it is shown that it is not possible to set general guidelines regarding the choice of the tab material. Failure modes of specimens where the tabs are bonded and where the tabs are molded directly on the test material were compared. Molded specimens produce better quality results.
Acute and Chronic Dopamine Receptor Stimulation Modulates AMPA Receptor Trafficking in Nucleus Accumbens Neurons Cocultured with Prefrontal Cortex Neurons
Authors: Sun Xiu , Milovanovic Michael , Zhao Yun , Wolf Marina E.
Published: April 2008

Postsynaptic interactions between dopamine (DA) and glutamate receptors in the nucleus accumbens (NAc) are critical for addiction. To determine the effect of acute and repeated DA receptor stimulation on AMPA receptor (AMPAR) synaptic targeting in medium spiny NAc neurons, we developed a model system consisting of rat NAc neurons cocultured with prefrontal cortex neurons from enhanced green fluorescent protein-expressing mice. Cortical neurons restore excitatory input onto NAc neurons but are distinguishable based on fluorescence. First, we showed that brief D1-like agonist exposure increased AMPAR insertion onto extrasynaptic regions of NAc neuronal processes through a mechanism requiring protein kinase A. This facilitated the Ca2+/calmodulin dependent protein kinase II (CaMKII)-dependent synaptic incorporation of AMPARs in response to subsequent NMDA receptor (NMDAR) stimulation. Through this mechanism, DA may promote reward- and drug-related plasticity in the NAc. Then, to model effects of repeatedin vivococaine exposure, we treated cocultures with DA (1 μm, 30 min) on days 7, 9, and 11 in culture. On day 15, NAc neurons exhibited increased synaptic AMPAR levels. This was associated with CaMKII activation and was blocked by the CaMKII inhibitor KN-93 (N-[2-[N-(4-chlorocinnamyl)-N-methylaminomethyl]phenyl]-N-(2-hydroxyethyl)-4-methoxybenzenesulfonamide phosphate salt). Furthermore, D1-like agonist exposure on day 15 no longer increased AMPAR surface expression. This refractoriness was associated with decreased D1receptor surface expression. NMDAR surface expression was not altered by acute or repeated DA receptor stimulation. These results suggest that (1) after repeated DA treatment, NAc neurons are more responsive to glutamate inputs but D1-like receptor regulation of plasticity is impaired, and (2) NAc/prefrontal cortex cocultures are useful for studying dopamine-induced neuroadaptations.
Dynamics of the Microglial/Amyloid Interaction Indicate a Role in Plaque Maintenance
Authors: Bolmont Tristan , Haiss Florent , Eicke Daniel , Radde Rebecca , Mathis Chester A. , Klunk William E. , Kohsaka Shinichi , Jucker Mathias , Calhoun Michael E.
Published: April 2008

Microglial cells aggregate around amyloid plaques in Alzheimer's disease, but, despite their therapeutic potential, various aspects of their reactive kinetics and role in plaque pathogenesis remain hypothetical. Through use ofin vivoimaging and quantitative morphological measures in transgenic mice, we demonstrate that local resident microglia rapidly react to plaque formation by extending processes and subsequently migrating toward plaques, in which individual transformed microglia somata remain spatially stable for weeks. The number of plaque-associated microglia increased at a rate of almost three per plaque per month, independent of plaque volume. Larger plaques were surrounded by larger microglia, and a subset of plaques changed in size over time, with an increase or decrease related to the volume of associated microglia. Far from adopting a more static role, plaque-associated microglia retained rapid process and membrane movement at the plaque/glia interface. Microglia internalized systemically injected amyloid-binding dye at a much higher rate in the vicinity of plaques. These results indicate a role for microglia in plaque maintenance and provide a model with multiple targets for therapeutic intervention.
Silencing the Kir4.1 Potassium Channel Subunit in Satellite Glial Cells of the Rat Trigeminal Ganglion Results in Pain-Like Behavior in the Absence of Nerve Injury
Authors: Vit Jean-Philippe , Ohara Peter T. , Bhargava Aditi , Kelley Kanwar , Jasmin Luc
Published: April 2008

Growing evidence suggests that changes in the ion buffering capacity of glial cells can give rise to neuropathic pain. In the CNS, potassium ion (K+) buffering is dependent on the glia-specific inward rectifying K+channel Kir4.1. We recently reported that the satellite glial cells that surround primary sensory neurons located in sensory ganglia of the peripheral nervous system also express Kir4.1, whereas the neurons do not. In the present study, we show that, in the rat trigeminal ganglion, the location of the primary sensory neurons for face sensation, specific silencing of Kir4.1 using RNA interference leads to spontaneous and evoked facial pain-like behavior in freely moving rats. We also show that Kir4.1 in the trigeminal ganglion is reduced after chronic constriction injury of the infraorbital nerve. These findings suggests that neuropathic pain can result from a change in expression of a single K+channel in peripheral glial cells, raising the possibility of targeting Kir4.1 to treat pain in general and particularly neuropathic pain that occurs in the absence of nerve injury.
Electronic Spectra of Hydrogen-Bonded Self and Water Complexes of Indazole
Authors: Jalviste Erko , Dziarzhytski Siarhei , Temps Friedrich
Published: April 2008

Ultraviolet absorption bands of hydrogen-bonded dimers and trimers of indazole (Ia2, Ia3) and several indazole-water complexes (Ia·H2O, Ia·(H2O)2, and Ia2·H2O) have been identified in a He supersonic jet seeded with indazole vapor. Spectra were recorded using laser induced fluorescence (LIF) excitation, burn-probe type fluorescence-dip hole-burning, and one-color mass-resolved resonance enhanced two-photon ionization (R2PI) spectroscopies. Excitation laser power dependent changes in the spectra have been ascribed to optical saturation, dissociation by breaking of hydrogen bonds of a complex, and other fragmentation effects.
Architecture, Space, and Abstraction in the Eighteenth-Century French Public Sphere
Authors: Wittman Richard
Published: April 2008

This essay investigates the spatial dimensions of the eighteenth-century transformation of the public sphere through the lens of contemporary French architectural culture. It analyzes not only how architecture was translated into discursive forms so as to maintain its publicity within a spatially exploded, informational public sphere but also how the concreteness of architecture and real spatial experience was sometimes appropriated in order to render the abstractions consecrated by this public sphere—like public opinion and the general will—less nebulous.
Whose Magic Flute?
Authors: Tettlebaum Marianne
Published: April 2008

This article argues that determining whose agency is behind the instrument of the magic flute in Mozart's The Magic Flute is crucial to understanding the mode of representation at stake in the opera. This examination is expanded, using Plato's Symposium, to suggest that the role of the flute-player in the opera has a necessary relationship to the practice of interpretation and criticism.
John Cage's Muzak-Plus: The Fu(rni)ture of Music
Authors: Vanel Herve
Published: April 2008

This article investigates the relationships between Muzak and the work of the avant-garde composer John Cage as one of the many unexplored links between the most advanced artistic endeavors and the aesthetics of the commercial and corporate environment. It suggests that the difference between the art of Cage ("Muzak-Plus") and the commercial music by the Muzak Corporation lies less in what superficially distinguishes them than in their common attempt to affect and shape society by the means of an aesthetic product designed to dissolve into life itself.
Preparation of highly oriented polycrystalline AlN thin films deposited on glass at oblique-angle incidence
Authors: Rodríguez-Navarro A. , Otañno-Rivera W. , García-Ruiz J. M. , Messier R. , Pilione L. J.
Published: April 2008

A new method to prepare polycrystalline AlN thin films biaxially oriented on amorphous substrates has been demonstrated. The films were deposited at different angles of incidence with a rf sputtering system. Population-1 crystallites, oriented with their c-axis pointing toward the incoming flux with random orientation in aximuthal directions, predominate at low angle of incidence (near normal). Population-2 crystallites result from non-normal incidence and have their c-axis tilted away from the incoming flux and predominate at high, near glancing, angle of incidence. The alignment of crystallites (population-2) increases with angle of incidence. Crystallites align along the [11*0] channeling direction, characterized by a low sputtering yield, while misoriented crystal grains suffer a higher resputtering and their growth is inhibited. For films deposited at 75°, the FWHM of an x-ray ϕ scan profile is 25°, indicating a high in-plane alignment.
Influence of Ar impurities on optical refractive index of sputter deposited a–Si films
Authors: Takahashi Hiroki , Kataoka Haruki , Nagata Hirotoshi
Published: April 2008

Amorphous Si (a–Si) films, sputter deposited under lower Ar pressure conditions, include numerous Ar atoms and exhibit high refractive indices, higher even than that of crystalline Si (c–Si), notwithstanding their lower Si densities. Such behavior in the refractive indices of the films was inconsistent with the conventional explanation considering only the density term in the Clausius–Mossotti relation. In the present study, the contribution of the polarizability changes of the films is proposed in order to account for the result in the refractive index. The molecular orbital (MO) calculations and experiments reveal that the polarizability of the a–Si film is sensitive to change in the angular distortion of the Si–Si bonds brought on by changing deposition conditions. The incorporated Ar atoms are found to cause the distortion in the Si network, leading to higher refractive indices for the less densified films.
The effects of the atmosphere on the surface modification of alumina by pulsed-laser-irradiation
Authors: Cao Siqi , Pedraza A. J. , Allard L. F. , Lowndes D. H.
Published: April 2008

A near-surface thin layer is melted when alumina is pulsed-laser-irradiated in an Ar–4% H2 atmosphere or in air. A thin layer of amorphous phase forms when the substrates are irradiated in Ar–4% H2 at 1 to 1.3 J/cm2 with multiple laser pulses. Amorphous phase is also found in samples laser-irradiated in air and oxygen. After a laser pulse at an energy density of 1.6 J/cm2 or higher the melt solidifies epitaxially from the unmelted substrate with a cellular microstructure. There is a decrease in the cooling rate of the melt as the laser energy density is increased because more heat must be dissipated. The amorphous phase forms when the heat input due to the laser pulse produces a superheated melt that cools down sufficiently fast to avoid crystallization. Very small particles of aluminum in the laser-melted and subsequently solidified layer are observed only in samples laser-irradiated in an Ar–4% H2 atmosphere. In this reducing atmosphere, the alumina is possibly reduced to metallic aluminum which is mixed into the melt by the turbulence provoked by the laser pulses. The effects of these metallic particles on copper deposition when the irradiated substrates are immersed in an electroless bath are discussed.
Characterization of nanophase titania particles synthesized using in situ steric stabilization
Authors: Gaynor A. G. , Gonzalez R. J. , Davis R. M. , Zallen R.
Published: April 2008

Ultrafine titania particles were synthesized from titanium tetraethoxide (TEOT) dissolved in ethanol. The concentration of water and of the soluble polymer hydroxypropylcellulose (HPC) were varied to control particle size. The HPC adsorbed onto the titania particles during growth, providing a steric barrier to aggregation. Electron microscopy showed that particles smaller than 70 nm were formed at high water concentrations (R > 120 where R is the molar ratio [H2O]/[TEOT]) and in the presence of HPC. The annealing-induced, phase-transformation behavior of these particles (amorphous → anatase → rutile) from 100 to 1000 °C was characterized by x-ray, Raman, and infrared techniques. The conversion of anatase to rutile occurred more readily for particles made at high water concentrations and with HPC. For particles formed by premixing TEOT with HPC prior to hydrolysis at R = 155, an 800 °C anneal yielded a rutile fraction exceeding 95%; particles made at R = 5.5 with no HPC showed negligible conversion at this temperature.
Radiation-induced phase transformations in MgAl2O4 spinel
Authors: Yu Ning , Devanathan Ram , Sickafus Kurt E. , Nastasi Michael
Published: April 2008

Ion-irradiation was observed to transform MgAl2O4 spinel first to a metastable crystalline phase and then to an amorphous phase at cryogenic temperatures. Elastic stiffening of 15% occurred upon formation of the metastable crystalline phase. A second transformation from the metastable crystalline spinel to an amorphous state was accompanied by elastic softening of 25% relative to unirradiated spinel. This phase transformation behavior in spinel appears to be different from that in intermetallic compounds where only elastic softening associated with radiation damage accumulation is observed. A two-stage radiation damage model is proposed to explain the observed phase transformations.
Microstructure evolution in amorphous Ge/Si multilayers grown by magnetron sputter deposition
Authors: Järrendahl K. , Ivanov I. , Sundgren J-E. , Radnóczi G. , Czigany Zs. , Greene J. E.
Published: April 2008

Microstructure evolution in amorphous Ge/Si multilayers grown by dual-target dc magnetron sputtering was investigated by cross-sectional transmission electron microscopy, x-ray diffraction, and growth simulations. In films grown under low intensity ion-irradiation conditions, the structure is columnar with low-density regions along column boundaries where layer intermixing was observed. By increasing the low-irradiation intensity (controlled by an applied negative substrate-bias), structures with smooth and well-defined layers could be grown. This was achieved at bias voltages between 80 and 140 V, depending on the sputtering gas pressure. As the ion-irradiation intensity is further increased, ion-induced intermixing degrades the layer interfaces and finally an amorphous Si1−xGex alloy forms. The combination of x-ray diffraction measurements and reflectivity calculations reveals an asymmetry between the Ge/Si and Si/Ge interface widths due, primarily, to a corresponding asymmetry in incident particle energies during the growth of alternate layers.
Percolative composite model for prediction of the properties of nanocrystalline materials
Authors: Chaim Rachman
Published: April 2008

A physical percolating composite model is presented for description of the changes in the transport-type properties with grain size in nanocrystalline materials. The model is based on hierarchial percolation through the different microstructural components such as grain boundaries, triple lines, and quadruple nodes at grain sizes when their respective percolation thresholds are reached. The model yields critical grain sizes at which the properties may change significantly. These grain sizes depend on the grain boundary thickness. Master curves were calculated for the elastic modulus and compared to the experimental data from the literature. Better fit was found with the experimental data in comparison to Hill's approximation model. The critical grain size at grain boundary percolation threshold is suggested as a criterion for definition of materials to exhibit nanocrystalline properties.
Influence of implantation of heavy metallic ions on the mechanical properties of two polymers, polystyrene and polyethylene terephthalate
Authors: Swain Michael V. , Perry Anthony J. , Treglio James R. , Elkind Alex , Demaree J. Derek
Published: April 2008

Ion implantation of polyethylene terephthalate (PET) and polystyrene (PS) with various high energy metallic ions at 70 kV and a dose of 3 × 1016 ions/cm2 has been made. Measurements of the mechanical properties of the polymers before and after implantation have been made with an ultra microindentation system using both pointed and a small (2 μm) radius spherical-tipped indenter. The surface regions were also investigated by atomic force microscopy (AFM) and Rutherford backscattering (RBS). Significant differences have been observed between the Ti–B dual-implanted surfaces and those of the Au and W implanted surfaces. For both the PET and PS, the resistance to indenter penetration at very low loads was much greater for the Ti–B dual-implanted surfaces. The estimated maximum hardness and modulus of the implanted materials were 0.3 and 8 GPa for the PET material and 1.4 and 16 GPa for the PS material. The results obtained with the spherical indenter show a gradual decline in effective modulus of the surface with penetration depth, whereas the hardness or contact pressure goes through a maximum before declining asymptotically to the bulk values. The values of hardness estimated for the spherical-tipped indenter are somewhat more conservative than the optimistic estimates with the Berkovich indenter. The improved increase in hardness for the Ti–B dual-implanted PET material scales with the RBS measured increased depth of implantation.
Técnicas corporais em Grupo de Gestantes: a experiência dos participantes
Authors: Hoga Luiza Akiko Komura , Reberte Luciana Magnoni
Published: April 2008

O objetivo deste estudo foi avaliar o emprego das técnicas corporais em um grupo de gestantes conforme a experiência dos participantes. Todos os participantes foram entrevistados após o encerramento do grupo desenvolvido em um Hospital Universitário. As categorias descritivas da experiência foram: as técnicas corporais promoveram alívio aos desconfortos, incentivaram à participação nas sessões e foram avaliadas positivamente; o emprego da abordagem corporal no grupo de gestantes promoveu o autocuidado de seus integrantes; as técnicas corporais intensificaram o envolvimento entre os casais e proporcionaram a integração dos participantes; há limitações no emprego da abordagem corporal no grupo de gestantes e em sua aplicabilidade no domicílio. A avaliação positiva do emprego de técnicas corporais em grupo de gestantes justifica sua recomendação.
Escala multidimensional de satisfação de vida para crianças: estudos de construção e validação
Authors: Giacomoni Claudia Hofheinz , Hutz Cláudio Simon
Published: April 2008

Os objetivos deste trabalho foram desenvolver uma escala, que foi intitulada de Escala Multidimensional de Satisfação de Vida para Crianças, assim como apresentar informações substanciais sobre as propriedades psicométricas do instrumento. Paralelamente, viabilizou-se a testagem do Modelo Multidimensional de Satisfação de Vida Infantil de Huebner. Foram realizados estudos de construção e de validação da escala. A versão final da Escala Multidimensional de Satisfação de Vida para Crianças contém 50 itens, distribuídos em seis fatores: self, self Comparado, Não-Violência, Família, Amizade e Escola. Foram encontradas consistências internas adequadas para cada uma das sub-escalas, assim como para a escala total. A validade concorrente das sub-escalas da escala multidimensional de satisfação de vida para crianças foi confirmada por correlações médias com medidas critério.
A crise da psicologia clínica no mundo contemporâneo
Authors: Portela Marco Antônio
Published: April 2008

O mundo contemporâneo determina novas formas de relação, que afetam a constituição da subjetividade e, por conseguinte, levam ao advento de um novo sujeito. Neste trabalho, fez-se uma análise a fim de compreender quem é o sujeito pós-moderno. No estudo realizado acerca do percurso da psicologia clínica, concluiu-se que suas principais abordagens são individualistas, confirmando o paradigma dominante, ou seja, o paradigma da subjetividade, que levou à exacerbação do individualismo na Pós-Modernidade. Procurou-se fazer uma análise da crise na clínica contemporânea, a fim de compreender suas causas e buscar saídas viáveis para os impasses que se apresentam. Este estudo pautou-se na idéia de que uma nova visão de mundo e do próprio homem está sendo presentemente construída, visão esta que aponta para conceitos como intersubjetividade, dialogia, narrativa, ecologia, entre outros, embora não tenha sido propósito deste trabalho aprofundar estes conceitos.
Acolhimento ao paciente e familia na unidade coronariana
Authors: Schneider Dulcinéia Ghizoni , Manschein Alessandra Maria Maia , Ausen Michelli Aparecida Bueno , Martins Josiane de Jesus , Albuquerque Gelson Luiz de
Published: April 2008

Pesquisa qualitativa, realizada nos meses de abril e maio de 2006, em uma unidade coronariana de um hospital público, especializado em cardiologia localizado na Região Sul do Brasil. Objetivou desenvolver uma proposta de implantação da tecnologia leve (acolhimento) no cuidado ao paciente/família, com diagnóstico clínico de infarto agudo do miocárdio. A construção da proposta foi embasada na percepção do paciente/família que vivenciaram a hospitalização na unidade coronariana. Os atores sociais foram nove pacientes/famílias. Para coletar os dados utilizou-se a entrevista e a observação sistemática. A análise dos dados foi fundamentada na análise de conteúdo. Os resultados destacam duas categorias: percepção paciente/família sobre o infarto; tecnologia de cuidado. Estas categorias favoreceram desenvolver uma proposta para usar a tecnologia leve ao paciente/família. Para o uso efetivo desta proposta é primordial o protagonismo de todos os envolvidos no cuidado em saúde não significando algo estanque, mas o que se pode produzir a partir desta.
A consulta de enfermagem no contexto da atenção básica de saúde, Juiz de Fora, Minas Gerais
Authors: Santos Sueli Maria dos Reis , Jesus Maria Cristina Pinto de , Amaral Arlete Maria Moreira do , Costa Darcília Maria Nagen da , Arcanjo Rafaela Alves
Published: April 2008

Estudo exploratório, descritivo, de abordagem qualitativa, com o objetivo de conhecer a percepção do enfermeiro sobre a realização da consulta de enfermagem na prática dos serviços de atenção básica. Dezesseis enfermeiros atuantes em Unidades Básicas de Saúde urbanas de Juiz de Fora -MG, foram entrevistados nos meses de outubro e novembro de 2006. Os dados foram organizados em temas e analisados à luz da literatura temática. Os resultados mostraram que a consulta de enfermagem é realizada pelos enfermeiros de forma limitada, sendo apontadas dificuldades como excesso de atividades burocráticas, deficiências na estrutura física da unidade de saúde e no entrosamento da equipe. Conclui-se que o enfermeiro considera importante a articulação entre o conhecimento teórico e a prática para a aquisição de competência na realização da consulta de enfermagem e que se faz importante buscar o atendimento integral, com vistas à maior resolutividade dos problemas de saúde dos usuários.
Triagem auditiva neonatal: aplicabilidade clínica na rotina dos médicos pediatras neonatologistas
Authors: Soares Carla Plech , Marques Lauralice Raposo , Flores Nayyara Glícia Calheiros
Published: April 2008

OBJETIVO: identificar a aplicabilidade clínica da triagem auditiva neonatal na rotina dos médicos pediatras neonatologistas no município de Maceió-AL. MÉTODOS: foi realizado um estudo transversal analítico com 36 médicos pediatras neonatologistas por meio da aplicação de um questionário com seis perguntas objetivas. RESULTADOS: observou-se que 88,9% dos pediatras neonatologistas conhecem a triagem auditiva neonatal, no entanto, 11,1% desconhecem. No serviço particular de saúde, 66,1% encaminham todos os recém-nascidos para a triagem em sua rotina. No serviço público, apenas 7,4% encaminham todos os recém-nascidos e 42,8% não encaminham. Em relação à Lei Municipal nº 5.555/06, que obriga a realização da triagem auditiva neonatal universal nas maternidades e estabelecimentos hospitalares congêneres no município de Maceió, 41,7% dos médicos declararam não conhecer. Apenas 36,1% afirmaram conhecer o trabalho fonoaudiológico na prevenção da surdez. CONCLUSÃO: neste estudo, pode-se concluir que a triagem auditiva neonatal está inserida na rotina clínica da maioria dos médicos pediatras neonatologistas que trabalham na rede particular de saúde. No entanto, observa-se carência de recursos para a implantação e continuidade do programa no serviço público e pouco conhecimento do papel do fonoaudiólogo na prevenção da surdez.
Caracterização do ceceio em pacientes de um Centro Clínico de Fonoaudiologia
Authors: Leite Antonelle Ferreira , Silva Sabrina Barros , Britto Ana Teresa Brandão de Oliveira e , Di Ninno Camila Queiroz de Moraes Silveira
Published: April 2008

OBJETIVO: Este estudo pretendeu verificar e caracterizar a ocorrência de ceceio, investigando a correlação entre o ceceio e a tonicidade da sílaba com [s] em diferentes contextos silábicos, observar se alguns desses contextos facilitam a produção correta de [s] e devem ser indicados como recurso terapêutico. MÉTODOS: Dos 54 pacientes em tratamento na clínica de Motricidade Oral do Centro Clínico de Fonoaudiologia foram selecionados, por meio da análise de prontuários, 16 pacientes na faixa etária entre 5 e 19 anos, de ambos os sexos e que apresentavam ceceio. Estes foram submetidos a teste de fala constituído da emissão de 79 palavras com [s] nas posições iniciais, finais e dentro da palavra, em sílabas átonas e tônicas seguidas das vogais [a], [e], [e], [i], , [o] e [u], registrado por meio de filmagem e gravação. Para análise estatística dos dados, foi utilizado o Teste Z para comparação de proporções e o software Minitab versão 14.0. RESULTADOS: Doze (75%) sujeitos pesquisados apresentaram ceceio anterior e 4 (25%), ceceio lateral. Não se observou diminuição do ceceio em relação à tonicidade da sílaba ou à co-articulação. Houve diminuição significativa do ceceio nas posições ataque inicial e ataque medial em relação às posições coda medial e final. CONCLUSÃO: A tonicidade silábica e a co-articulação com as diferentes vogais não alteram a incidência do ceceio. As posições iniciais de sílaba, porém, parecem ser facilitadoras da produção de [s] e devem, portanto ser consideradas na escolha do recurso e material a ser utilizado em terapia.
A influência da memória operacional nas habilidades de compreensão de leitura em escolares de 4ª série
Authors: Giangiacomo Micheli Cristina Paludeto Belaz , Navas Ana Luiza Gomes Pinto
Published: April 2008

OBJETIVOS: Investigar o papel da memória verbal e não-verbal, e do vocabulário expressivo na compreensão de leitura; avaliar as habilidades de memória e vocabulário em um grupo de crianças da 4ª série em relação ao desempenho de compreensão de leitura. MÉTODOS: Participaram do estudo 15 crianças com idades entre 9;11 anos e 11;4 anos. As crianças não possuíam queixas de perda auditiva, visual e/ou alterações neurológicas. Todos os sujeitos foram submetidos individualmente às avaliações de desempenho escolar, leitura, (decodificação, compreensão) vocabulário e memória operacional verbal e não-verbal. RESULTADOS: Houve correlação estatisticamente significante entre o conhecimento de vocabulário expressivo (r= 0,546, p= 0,035) e memória operacional verbal (r= -0,689, p=0,004) e o desempenho em compreensão neste grupo de crianças de 4ª. série de ensino fundamental, sem queixas de dificuldades escolares. Nem a memória não-verbal, nem a habilidade de decodificação de palavras influenciaram no desempenho em compreensão de leitura. CONCLUSÕES: O desempenho em vocabulário e a boa capacidade da memória operacional verbal foram fatores relevantes para garantir a compreensão de leitura nessa população.
Variation in phytate accumulation in common bean (Phaseolus vulgaris L.) fruit explants
Authors: Coelho Cileide Maria Medeiros , Bellato Cláudia Mattos , Garcia Andréia Karime Marcelino , Vitorello Victor Alexandre , Azevedo Ricardo Antunes
Published: April 2008

The in vitro synthesis of phytate was studied in common bean fruit explants. Different concentrations of sucrose; phosphorus (P); myo-inositol; abscisic acid (ABA); glutamine and methionine, were tested. Fixed concentrations of these compounds were tested at different periods (0, 3, 6 and 9 days). Variation in phytate coincided with different concentrations of sucrose, myo-inositol, P and ABA for the duration tested. These compounds caused an accumulation of phytate and were more effective in the presence of myo-inositol and P. The accumulation of P varied less than phytate for the different treatments tested in vitro. In conclusion, P, sucrose, ABA, and myo-inositol caused an increase in the phytate of bean seed, showing that it could be possible to alter its content by culturing bean fruit explants in vitro.
Semi-volatile compounds variation among Brazilian populations of Ilex paraguariensis St. Hil.
Authors: Cansian Rogério Luis , Mossi Altemir José , Mazutti Márcio , Oliveira José Vladimir , Paroul Natalia , Dariva Cláudio , Echeverrigaray Sérgio
Published: April 2008

The use of compressed carbon towards extracting semi-volatile compounds present in maté leaves (Ilex paraguariensis St. Hil.) is due to the growing interest in mate constituents to develop new products in the cosmetic, pharmaceutical and food industries. The objective of this work was to assess the chemical distribution of semi-volatile compounds in 20 native populations of maté collected all over Brazil. The extracts of bulk samples (30 plants) of each population were obtained by the high-pressure carbon dioxide extraction technique, and analyzed by GC/MSD. The quantification of compounds (caffeine, theobromine, phytol, squalene, vitamin E, eicosane, pentatriacontane, and stigmasterol) showed significant variations within the different populations and compounds analyzed, which are not related to geographical origin or macroclimate characteristics. The results pointed out to the importance of genetic and local environmental factors on the chemical composition of this species.
Cytogenetic study of two species of the family Pimelodidae (Siluriformes) collected in lago Guaíba, Rio Grande do Sul, Brazil
Authors: Treco Fernando Rodrigo , Malabarba Luiz R. , Giuliano-Caetano Lucia , Dias Ana Lúcia
Published: April 2008

A cytogenetic study was conducted on specimens of Parapimelodus nigribarbis and Pimelodus maculatus collected in the lago Guaíba drainage, Porto Alegre, Rio Grande do Sul, Brazil. The two species had a diploid number of 56 chromosomes, with P. nigribarbis showing a karyotype of 20m + 20sm + 4st + 12a with FN of 100, and P. maculatus showing a karyotype of 24m + 20sm + 6st + 6a with FN of 106. NORs were demonstrated in both species in only one pair of subtelocentric chromosomes, in the terminal region of the long arm, which was coincident with C- banding and CMA3 staining, while DAPI staining was negative in these regions. Parapimelodus nigribarbis had a greater number of heterochromatic bands than did P. maculatus, which were distributed mainly in the terminal regions, where the latter species showed an interstitial band on the short arm of the first metacentric pair. C-banding plus CMA3 demonstrated heterochromatin that was associated with GC-rich NORs in both P. nigribarbis and P. maculatus, although other fluorescent regions were also observed in the former species. With C-banding plus DAPI, various chromosomal regions were stained in the two species, along with interstitial staining in P. maculatus, indicating that heterochromatin contained a greater quantity of AT-rich regions.