bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Carbon Nanotube-Based Field Enhanced Thermionic Cathode
Authors: Jin Feng , Day Christopher
Published: April 2011

The electron emission properties and field enhancement effects of carbon nanotubes (CNTs) have been extensively studied. However, all of these studies focus only on the field emission aspect of the materials and its application in cold cathode electron emitters. So far, we have not seen any studies in the literature that link CNTs with thermionic cathodes, which are an equally important cathode type because of their many applications. We present a study of field enhanced electron emissions from a new type of cathode: the CNT-based field enhanced thermionic cathode. This new cathode consists of a metal substrate with CNTs grown on top of its surface. The CNTs are coated with thermionic emission materials (BaO, SrO, and CaO). This unique cathode structure takes advantage of both the field enhancement effect from CNTs and the high electron emission capability of thermionic materials. The electron emission properties of this new cathode, particularly the field enhancement factor and effective work function, are compared with the conventional thermionic cathodes that are made of same oxide coating.
Nanotube-based systems for broadband optical limiting: towards an operational system
Authors: Izard N. , Riehl D. , Anglaret E.
Published: April 2011

Nanotube-based systems are good candidates for optical limiting against broadband laser pulses. We explore new routes to improve their limiting performances. We show that the diameter of the nanotubes is a key factor to control the performances. On the other hand, we demonstrate that chemically modified nanotubes can be mixed with organic chromophores, leading to high performance composite limiting systems which are particularly efficient in the nanosecond regime due to the cumulative effects of nonlinear scattering and multiphoton absorption.
Corrections to the Optical Transition Energies in Single-Wall Carbon Nanotubes of Smaller Diameters
Authors: Samsonidze Georgii G. , Saito Riichiro , Jiang Jie , Grüneis Alexander , Kobayashi Naoki , Jorio Ado , Chou Shin G. , Dresselhaus Gene , Dresselhaus Mildred S.
Published: April 2011

Optical spectroscopy characterization of carbon nanotube samples requires accurate determination of their band structure and exciton binding energies. In this paper, we present a non-orthogonal density-functional based tight-binding calculation for the electronic transition energies in single-wall carbon nanotubes. We show that the curvature-induced rehybridization of the electronic orbitals, long-range atomic interactions, and geometrical structure relaxation all have a significant impact on the electronic transition energies in the small diameter limit. After including quasiparticle corrections and exciton binding energies, the calculated electronic transition energies show good agreement with the experimental transition energies observed by photoluminescence and resonance Raman spectroscopy.
Carbon Nanotube Electron Sources for Electron Microscopes
Authors: Jonge Niels de , Oostveen Jim T. , Rooij Theo van , Allioux Myriam , Doytcheva Maya , Kaiser Monja , Teo Kenneth B. K. , Lacerda Rodrigo G. , Milne William I.
Published: April 2011

High-quality electron sources can be made from individual multi-walled carbon nanotubes. A process was developed allowing the control over 1) the length of the fraction of the nanotube protruding from the support tip, 2) the contact length of the nanotube with the support tip, 3) the diameter of the nanotube. In addition, the cap of the nanotube was closed and the nanotube was cleaned thoroughly. The field emission model successfully describes the electron emission process of these electron sources and the work function is 5.1 eV. The emitters show a highly stable emission, as expected on account of the extremely stable structure of the carbon nanotube.
Cluster Diffusion and Coalescence on Metal Surfaces: applications of a Self-learning Kinetic Monte-Carlo method
Authors: Rahman Talat S. , Kara Abdelkader , Karim Altaf , Trushin Oleg
Published: April 2011

The Kinetic Monte Carlo (KMC) method has become an important tool for examination of phenomena like surface diffusion and thin film growth because of its ability to carry out simulations for time scales that are relevant to experiments. But the method generally has limited predictive power because of its reliance on predetermined atomic events and their energetics as input. We present a novel method, within the lattice gas model in which we combine standard KMC with automatic generation of a table of microscopic events, facilitated by a pattern recognition scheme. Each time the system encounters a new configuration, the algorithm initiates a procedure for saddle point search around a given energy minimum. Nontrivial paths are thus selected and the fully characterized transition path is permanently recorded in a database for future usage. The system thus automatically builds up all possible single and multiple atom processes that it needs for a sustained simulation. Application of the method to the examination of the diffusion of 2-dimensional adatom clusters on Cu(111) displays the key role played by specific diffusion processes and also reveals the presence of a number of multiple atom processes, whose importance is found to decrease with increasing cluster size and decreasing surface temperature. Similarly, the rate limiting steps in the coalescence of adatom islands are determined. Results are compared with those from experiments where available and with those from KMC simulations based on a fixed catalogue of diffusion processes.
Corrosion of archaeological model glasses after 32 years of burial at Ballidon
Authors: McLoughlin Sean D. , Hyatt Neil C. , Hand R. J. , Lee William E.
Published: April 2011

The groundwater corrosion of three archaeological model glass compositions, a replica Roman glass (B1), a medieval glass (B2) and a 17th century glass (B3), recovered from the Ballidon burial site, were investigated by field emission scanning electron microscopy. Given the equivalent burial conditions for all three glasses, the different corrosion mechanisms of these glasses are dependent principally upon composition, and in particular the dominant alkali and network former content. Composition B1 was found to the most durable glass and showed progressive Na leaching coupled with dissolution of the silicate matrix in the outermost 5μm after 32 years of burial. The B2 and B3 compositions were found to be less durable and corroded via congruent dissolution of the silicate matrix and in situ condensation, resulting in the formation of a discrete 5-15μm thick layer after only 1 year of burial. The formation of a protective Ca-rich surface layer was observed for B2, hindering successive inward growth of the dissolution reaction and favouring localised pitting of the extant layer. The protective surface phenomenon was not observed for B3, and a large increase in layer thickness was observed after nine years of burial.
Epistemic and Aleatory Uncertainty in Recommended, Generic Rock Kd Values used in Performance Assessment Studies
Authors: Crawford James , Neretnieks Ivars , Moreno Luis
Published: April 2011

Over the past decade or so there has been an explosion in the number of sorption modelling approaches and applications of sorption modelling for understanding and predicting solute transport in natural systems. The most widely used and simplest of all models, however, is that employing a constant distribution coefficient (Kd) relating the sorbed concentration of a solute on a mineral surface and its aqueous concentration.

There are a number of reasons why a constant partitioning coefficient is attractive to environmental modellers for predicting radionuclide retardation, and in spite of all the shortcomings and pitfalls associated with such an approach, it remains the leitmotif of most performance assessment transport modelling.

This paper examines the scientific basis underpinning the Kd-approach and its broad defensibility in a performance assessment framework. It also examines sources of epistemic and aleatory uncertainty that undermine confidence in Kd-values reported in the open literature. The paper focuses particularly upon the use of so-called “generic” data for generalised rock types that may not necessarily capture the full material property characteristics of site-specific materials.

From the examination of recent literature data, it appears that there are still a number of outstanding issues concerning interpretation of experimental laboratory data that need to be considered in greater detail before concluding that the recommended values used in performance assessments are indeed conservative.
Effects of Calcium Ion in Highly Alkaline Plume on Permeability Change of Flow-Path
Authors: Usui Hideo , Niibori Yuichi , Tanaka Koichi , Tochiyama Osamu , Mimura Hitoshi
Published: April 2011

For the construction of the geological disposal system of radioactive wastes, a large amount of cement is used. Such a material alters the pH of groundwater to highly alkaline region [1-3]. The highly alkaline plume contains rich Ca ion compared to the surrounding environment, and the Ca ions reacts with soluble silicic acid. Its product would deposit on the surface of flow-paths in the natural barrier and decrease the permeability. In this study, the influence of Ca ion in highly alkaline plume on flow-paths has been examined by using packed bed column.

The column was packed with the amorphous silica particles of 75-150 μm in diameter. The Ca(OH)2 solution (0.78 mM, 4.37 mM, and 8.48 mM, pH:12.2∼12.3) was continuously injected into the column at constant flow rate (1.1 mm/s), and the change of permeability was continuously monitored. At the same time, [Ca]total and [Si] in the eluted solution was measured by the inductively coupled plasma atomic emission spectrometry (ICP-AES). The Ca(OH)2 solutions were prepared with CO2-free pure water, and filtrated through 0.22 μm and 0.45 μm filter. The permeability was normalized by the initial permeability value.

The experimental results showed that the permeability change and the chemical reactions in the packed bed depended on the concentration of Ca(OH)2 in the feed solution. The SEM images showed that the feed solution of 8.48 mM in [Ca]total apparently altered the particle surface with the products with Ca (deposition). Moreover, from the distribution of Ca on the cross section of packed particle (by EPMA), it was found that Ca deposited also in the inner pores of the particle. These results suggest that the deposition does not always change the permeability in the early stage of precipitation reaction. In the eluted solution, the concentrations of Ca and Si dramatically changed, depending on the concentration of Ca in the feed solution.
Development of Low Alkaline Cement Considering Pozzolanic Reaction for Support System in HLW Repository Construction
Authors: Nakayama Masashi , Iriya Keishiro , Fujishima Atsushi , Mihara Morihiro , Hatanaka Koichiro , Kurihara Yuji , Yui Mikazu
Published: April 2011

Cementitious materials have been studied for their applicability as support and lining in the construction of shafts and tunnels of the underground facilities for HLW disposal system. However, in the case of Ordinary Portland Cement (OPC), the buffer materials and the host rock may be altered due to the high alkalinity of groundwater contacting the OPC in the long-term. Low alkaline cements with high content of pozzolanic material were developed in order to reduce such hyper alkaline alteration. This paper shows that the pH of the leaching solution of this cement is about 11, and that it can be applied for full scale lining and for shotcrete.
An Experimental Approach on the Effect of Rock Alteration on Sorption Behavior
Authors: Niibori Yuichi , Kasuga Yasunori , Yoshikawa Hiroaki , Tanaka Kouichi , Tochiyama Osamu , Mimura Hitoshi
Published: April 2011

In the geological disposal of radioactive wastes, cement used for the repository construction alters the condition of groundwater to highly alkaline of pH about 13. Such alkaline groundwater around the repository would alter the surfaces of the rocks in the flow paths to the amorphous phase. Once the surface is altered, it takes a geological period (so much long time) to restore the surface to its former condition. This study examined the sorption behavior of europium (Eu-152 (tracer), Eu-151 (5×10-5 M, carrier) onto some silica minerals with polymeric silicic acid. Polymeric silicic acid also affects the alteration of the solid surface.

The results showed that the kinds of silica minerals strongly affect the sorption behavior in the range of 5<pH<8. The main difference was due to the degree of crystallization of the solid phase, the specific surface area and the concentration of polymeric silicic acid. Since the amorphous silica or polymeric silicic acid takes a loose structure, the isoelectric point is high compared to the crystal ones such as opal-CT and cristobalite, which in turn decreases the sorption. The crystalline silica with polymeric silicic acid remarkably decreased the sorption of europium. This suggested that the surface of solid phase was altered by polymeric silicic acid.
Cathodoluminescence study of americium incorporation into calcite single crystals
Authors: Zamoryanskaya Maria V. , Burakov Boris E. , Kolesnikova Ekaterina V. , Zuykov Michael A.
Published: April 2011

In order to study americium incorporation into calcite, CaCO3, under conditions of crystal growth, two samples of single crystal Am-doped calcite were synthesized and studied by cathodoluminescence (CL) spectroscopy in comparison with undoped and Eu-doped artificial calcite. Americium contents in calcite crystals were (in kBq/g): 1) 6.9; 2) 1.9(E+4). The CL emission of undoped and Am-Eu-doped calcitesamples was characterized by three broad bands at 2.03; 2.47 and 2.96 eV. Weak CL lines related to typical transitions 5D07F1,2,4 of Eu3+ and Am3+ions were observed at 1.68; 1.99, 2.06 eV and 1.60; 1.98 eV, respectively. Degrading of calcite structure under irradiation has been studied using CL emission of high power electron beam.
Silver Zeolites: Iodide Occlusion and conversion to Sodalite – a potential 129I waste form?
Authors: Sheppard Gareth P , Hriljac Joseph A , Maddrell Ewan R , Hyatt Neil C
Published: April 2011

Silver exchanged zeolites A, X and Y were used to occlude silver iodide (AgI) at 400°C. Heating to 900°C in a hot isostatic press caused decomposition of the zeolite materials and the formation of more dense phases. Silver zeolites A and X both formed sodalite, seen as a potential 129I waste form, while silver zeolite Y formed an x-ray amorphous phase containing AgI. Silver zeolite A produced the best potential waste form, a monolithic sodalite with negligible porosity.
Microchemical and crystallographic characterisation of fluorite-based ceramic wasteforms
Authors: Stennett Martin C. , Hyatt Neil C. , Maddrell Ewan R. , Gibb Fergus G. F. , Moebus Guenter , Lee William E.
Published: April 2011

A number of possible options have been proposed for the encapsulation and immobilisation of long lived actinide (Act) fractions in nuclear waste. Ceramics offer superior durability against chemical migration and the ability to be tailored to accommodate a variety ofdifferent waste streams. Research on the fabrication of dense, durable crystalline matrices for the safe disposal of fissile plutonium is ongoing and this study reports quantitative chemical, structural and spectroscopic analysis on fluorite based host phases.

Ceramics based on the fluorite structure are known to be able to incorporate a variety of actinides and in this work two candidate ceramic matrices were investigated: a pyrochlore, Gd2Zr1.60Ce0.20Hf0.20O7; and a zirconolite, (Ca0.90Gd0.10)(Zr0.50Ce0.20Hf0.20Gd0.10)Ti2O7. The chemical compositions of the two major phases observed in the ‘zirconolite’ sample were consistent with the 2M and 4M zirconolite polytypes and the presence of the 4M structure was confirmed by Electron Diffraction (ED). The major phase in the ‘pyrochlore’ ceramic was confirmed by ED to have the pyrochlore structure. Electron Energy Loss Spectroscopy (EELS) data indicated the presence of both Ce3+ and Ce4+ in all the samples.
Porous Materials Based on Cenospheres of Coal Fly Ash for Fixation of Cs-137 and Sr-90 in Mineral-like Aluminosilicates
Authors: Vereshchagina Tatiana A. , Vasilieva Natalia G. , Vereshchagin Sergei N. , Paretskov Evgenyi N. , Zykova Irina D. , Kruchek Dmitryi M. , Manakova Ludmila F. , Tretyakov Alexander A. , Anshits Alexander G.
Published: April 2011

Among the crystalline matrices being developed for immobilization of 137Cs and 90Sr are framework aluminosilicates like feldspars and feldspathoids. A novel approach to obtain mineral-like aluminosilicate forms of 137Cs and 90Sr with using porous materials based on hollow aluminosilicate microspheres of coal fly ash (cenospheres) has been demonstrated. Two modifications of microspherical porous materials have been developed, (i) moulded porous matrices based on consolidated cenospheres and (ii) zeolite sorbents obtained by hydrothermal zeolitization of cenospheres. The first includes impregnation of Cs- or Sr-containing solutions into porous matrices, drying and calcining at temperatures (700-900°C) lower than the softening point of the porous matrix material, at which solid phase crystallization takes place with formation of framework aluminosilicates, such as Cs-nepheline, pollucite or Sr-anorthite. Using zeolite sorbents, immobilization of Cs+ and Sr2+ proceeds through the step of trapping ions from the solution followed by drying and thermochemical solid-phase transformation of saturated zeolites into pollucite or Sr-anorthite over the same temperature range. Cenosphere-derived porous matrices and zeolite sorbents were tested in fixation of 137Cs using spiked simulants of actual radioactive waste. The durability of crystalline aluminosilicate 137Cs -forms obtained was shown to satisfy Russian (GOST P 50926-96) and international standards.
Leaching of Cesium and Uranium from Spent PWR fuel in the Gel-state Clays
Authors: Kim S. S. , Chun K. S. , Choi J. W. , Cho W. J. , Hahn P. S.
Published: April 2011

The amounts of cesium and uranium released from crushed spent PWR fuel in the gel-state clays with a few ml of supernatant at hot cell temperature under Ar-atmosphere have been measured. The fractions of cesium dissolved from the fuel for 873 days were 0.29 and 0.25% in Boom clay/Boom-clay water and Ca-bentonite/synthetic granitic groundwater, respectively. These cesium fractions were very close to the gap inventory of cesium, which was determined to be around 0.30% in the previous experiment. The fraction of uranium released up to 193 days in the Boom clay media was 0.011% and this fraction has been retained until 873 days. Such this phenomenon was also obtained in the Ca-bentonite media even though the released fraction was higher than that in Boom clay. The increase of less than 0.001% in the dissolved uranium fraction between 193 and 873 days suggests that the long-term leach rate of uranium from spent fuel would be much less than 24 μg·m−2·day−1.
Long-Term Behavior of Embiez Archaeological Glass: Results after 1800 Years of Alteration in a Marine Environment
Authors: Gin Stéphane , Chouchan Jean-Louis , Foy Danièle
Published: April 2011

An archaeological glass initially fractured and altered for 1800 years in a marine environment is now being examined by the CEA because of its strong morphological similarity to the nuclear glasses used for immobilization of long-lived radionuclides (i.e. the presence of fractures and cracks formed during cooling, which significantly increase the surface area accessible to water). The issue concerns glass alteration by water, and in particular the different behavior of the external surfaces in contact with a solution highly renewed and the internal surfaces, which constitute a much more confined medium.

The preliminary results of this study are discussed. The cracks in the archaeological glass have been filled by crystallized alteration products formed jointly by elements from the glass and elements dissolved in seawater. The glass is distinctly less altered (by a factor of 10 to 100) on the internal surfaces generated by the cracks than on the external surfaces. The forward glass dissolution rate was measured at different temperatures on pristine glass samples and under conditions that allowed us to estimate the dissolution rate of the external surfaces under realistic conditions at about 200 μm in 1800 years. The implications of this study are then discussed.
Modelling The Alteration of Son-68 Glass with Nearfield Materials
Authors: de Combarieu G. , Barboux P. , Godon N. , Minet Y. , Gin S.
Published: April 2011

The model tested in this paper couples glass dissolution rate and geochemistry in the surrounding environment, thus leading to the comprehensive description of the interactions between the glass and the minerals and their transformations. Leaching of glass is simulated at 90°C and S/V=80 cm-1 in pure water or with iron from the canister and overpack or with argillite. The glass dissolution is described with an affinity law with respect to a nontronite-like phase, which saturation state depends on Si, Al, Fe, Na and Ca activities. The simulations results allow to reproduce both the decrease of the initial alteration rate and the so-called residual regime while the composition of the alteration layers are explained in terms of precipitated phases. In presence of metallic iron, the corrosion does not affect much glass dissolution rate if silica sorption is neglected. On the contrary, in presence of argillite, the alteration is enhanced by the dissolution of primary clay minerals and the precipitation of feldspar, K-zeolite and clay minerals.
Immobilisation of Simulated Plutonium-Contaminated Material in Phosphate Glass: An Initial Scoping Study
Authors: Bingham Paul A. , Hand Russell J. , Scales Charlie R.
Published: April 2011

Vitrification is a potential route for the immobilisation of Plutonium Contaminated Material (PCM). This is an Intermediate Level Waste (ILW) arising from operations in which there is contact with Pu isotopes. PCM consists of low levels of Pu combined with metals, masonry, glass, ceramics, polymers and other carbonaceous materials. Simulated PCM containing CeO2 as a PuO2 surrogate was mixed with a phosphate precursor and vitrified. Pre-oxidation of PCM simulant prior to vitrification minimised the violence of batch reactions. No pre-oxidation produced inhomogeneous slag-like materials with high residual metals and particulates. Pre-oxidation at 600°C in air and at 1200°C in an O2-rich atmosphere produced more favourable results, with increasingly vitreous products resulting from more oxidised PCM simulant. The most oxidised PCM simulant produced phosphate glasses with low levels of particulate inclusions, as confirmed by x-ray diffraction and scanning electron microscopy. Particulates included iron-rich metallics and aluminous oxides. Increased melting times and temperatures may have reduced the number of inclusions slightly, but O2 bubbling during melting resulted in little additional benefit. Waste loading equivalent to ∼60 weight % of untreated waste may be possible. There was little evidence of Ce partitioning, indicating that it was immobilised within the glass matrix and had little preference for metallic or crystalline phases. These results demonstrate the potential feasibility for vitrification of PCM in phosphate glass, justifying further investigation into this potentially novel solution.
Chemical durability and performance of assessment of spent fuel and high level waste forms under simulated repository conditions – Spanish contribution to IAEA project
Authors: Martínez-Esparza Aurora , Gago José Antonio , Quiñones Javier , Iglesias Eduardo , Cera Esther , Merino Juan , de Pablo Joan , Casas Ignasi
Published: April 2011

Chemical durability of spent fuel under repository conditions is one of the main topics of interest in national and international projects from the last two decades. During the last decade there have been growing the activities in Enresa related to the deep disposal concept with the aim of developing a spent fuel alteration model for the understanding of the behaviour of this nuclear waste under repository conditions. In this context, the development and utilisation of models and sub-models based on experimental work have been of great importance.

Experimental studies with spent fuel(in Collaboration Agreement with ITU) and spent fuel analogues in several environmental conditions have been carried out into Enresa R+D Programmes in order to reach a better knowledge of the relevant processes and to quantify the spent fuel chemical durability under repository conditions.

In this work, it is showed the utility of data provided from experiments with spent fuel analogues to test the mechanisms and the influence of relevant parameters in the spent fuel alteration under repository conditions.

The evolution of irradiated fuel under interim storage conditions and in deep geologic storage and its oxygen to metal ratio (O/M) before the water access to the fuel is another factor of great influence on enhanced spent fuel leaching. This effect has been also studied by means of spent fuel analogues and by using simulated (artificially) aged fuel.
Particle Size Control, Structure and Magnetic Characterization of Cobalt Nanoparticles
Authors: Singh Abhishek , Parekh Nirav , Young Gregory , Parvin Kiumars , Kaur Maninder , Bruck David , Wong Spencer , Varasteh Mehdi
Published: April 2011

Cobalt nanoparticles were synthesized by means of a hot metal reduction reaction with cobalt chloride as precursor material. The size of cobalt nanoparticles was controlled by the choice of surfactant and the molar ratio of surfactant-to-reagent. Surfactants with larger alkane side chains yielded a smaller average nanoparticle size (diameter) and tighter size distribution, as these chains provided steric hindrance to the growth of the nanoparticles after initial nucleation. For each alkane side chain, a high molar ratio of surfactant-to-reagent (HSR) rendered nanoparticles with smaller particle size, while a low molar ratio of surfactant-to-reagent (LSR) produced larger nanoparticles. Measurements on transmission electron microscope images of cobalt particles synthesized with tri-octylphosphine revealed an average particle size of 6.9 nm (HSR) and 9.1 nm (LSR), while particles synthesized with tri-butylphosphine had a mean diameter of 12.5 nm (HSR) and 14.9 nm (LSR). X-ray diffraction profiles indicated that particles had metastable ε-cobalt structure. Room temperature magnetization measurements showed ferromagnetic behavior with highly square M-H loops indicative of single domain particles with coercive fields in the range of 400–500 Oe.
Effects of FM/NM Interfaces on Spin Accumulation in Free Layer of Pseudo-Spin-Valve Structure
Authors: Hu Jiuning , Ren Min , Zhang Lei , Deng Ning , Dong Hao , Chen Peiyi
Published: April 2011

The ferromagnetic/nonmagnetic (FM/NM) interfacial effects on the spin accumulation in the free layer were studied in a pseudo-spin-valve structure (PSVs) consisting of two FM layers separated by a NM spacer layer. We developed a spin current model for the current-induced magnetic switching (CIMS) effect based on the spin diffusion equations and appropriate boundary conditions, and derived a new formula for the spin-dependent electrochemical potentials that are related to the spin-dependent density of states. The results indicate that the spin accumulation in the free layer mainly depends on the interfacial spin asymmetry coefficient Ξ?which originates from the spin-dependent interfacial conductance. In the parallel (anti-parallel) configuration of the magnetization direction for the free and fixed layer, the positive (negative) electron current (electrons from the free layer to the fixed layer and vice versa) drives the spin current polarization factor at the interface between the top electrode and the free layer to vary from Ξ? (-Ξ?) to 0, while at the interface between the free layer and the spacer layer the spin current polarization factor vary from Ξ? (0) to Ξ?/2, which means the total spin current polarization factor in the free layer varies from 0 (Ξ?) to Ξ?/2. These results show that the anti-parallel configuration has a less critical switching current than that of the parallel configuration. Thus, we can design PSVs with symmetrical critical current based on the model.
Nonlinear Damping Generated by Spin Injection in a Pseudo-spin-valve Structure
Authors: Ren Min , Zhang Lei , Hu Jiuning , Deng Ning , Dong Hao , Chen Peiyi
Published: April 2011

The current induced magnetic dynamics of a nano-scale pseudo-spin-valve (PSV) structure was theoretically studied. The spin relaxation mechanisms and the influence of ferromagnetic/nonmagnetic (FM/NM) interfaces on the current polarization were investigated, and a modified magnetic dynamic equation was developed. Both the free layer's local magnetic moments and itinerant electrons' spins were regarded as a macro-spin, whose movement was resulted from two items: spin relaxation due to the magnetic damping and spin accumulation due to the polarized current. The injected current not only produces a spin transfer torque, but also alters the effective magnetic field, and thus affects the damping. Therefore, the damping is nonlinear and correlated to the current. Based on the analysis of the competition between magnetic damping and spin accumulation, the dynamic behaviors of magnetization switching and oscillation can be explained.
Influência do nível de força máxima na produção e manutenção da potência muscular
Authors: Paulo Anderson Caetano , Tavares Lucas Duarte , Cardoso Ronaldo Kobal , Lamas Leonardo , Pivetti Bruno , Tricoli Valmor
Published: April 2011

Indivíduos mais fortes (com nível mais elevado de força máxima, Fmax) demonstram menor resistência de força que indivíduos mais fracos (com nível mais baixo de Fmax) em uma mesma intensidade relativa. Como o nível de Fmax influencia a produção de potência, espera-se que sujeitos mais fortes também apresentem uma menor resistência de potência. O objetivo deste estudo foi avaliar a influência do nível de Fmax na produção e na resistência de potência durante repetições e séries múltiplas do exercício meio-agachamento. Quarenta e dois sujeitos foram classificados de acordo com o resultado no teste de força dinâmica máxima (1RM) e destes os 10 mais fortes e os 10 mais fracos foram selecionados para participar no estudo. Para avaliar a resistência de potência os dois grupos realizaram 10 séries de seis repetições a 40% e a 60% 1RM na maior velocidade possível. A potência absoluta (PA) e a potência relativa ao peso corporal (PR) desenvolvidas na fase concêntrica do exercício foram medidas. A análise de variância (ANOVA two-way) revelou que os sujeitos mais fortes diminuíram a PA a 60% 1RM a partir da quarta repetição e a PR a partir da quinta repetição. Já os sujeitos mais fracos diminuíram a PA apenas na sexta repetição e mantiveram o rendimento na PR ao longo das 10 séries. Não houve efeito significante na intensidade de 40% 1RM. Isso sugere que sujeitos mais fortes fadigam antes em maiores intensidades de carga. Essa fadiga precoce nos sujeitos mais fortes poderia estar ligada a diferentes fatores associados ao controle da homeostase orgânica como o comportamento da pressão arterial, da atividade eletromiográfica e a proporção de fibras musculares dos tipos I e II.
Are We Postmodern Yet? ReadingMonsterWith 21st‐Century Ninth Graders
Authors: Groenke Susan Lee , Youngquist Michelle
Published: April 2011

When the authors taught Walter Dean Myers's postmodern young adult novelMonsterto ninth graders, they assumed the students would like the text, as its format and style resemble that of popular television crime shows. The authors also assumed the students would be savvy readers of the text, capable of understanding and integrating postmodern elements to make thematic connections. Yet, the authors' classroom research revealed that students were confused by the novel's format, and some students seemed to bring traditional narrative expectations to their reading of the text. In the article, the authors share excerpts from the students' online chat discussions to highlight where much of the students' reading confusion occurred. The authors end with suggestions for future teaching and implications.
Reading Is Your Thing (Even if You're Not a Reading Teacher)
Authors: Zwiers Jeff
Published: April 2011

The following activities, Prediction Path and Quotation Café, are adapted from the IRA book Building Reading Comprehension Habits in Grades 6–12. They highlight the reading comprehension habit of making inferences and predictions, which can be used across content areas and grade levels.
Extending Readers Theatre: A Powerful and Purposeful Match With Podcasting
Authors: Vasinda Sheri , McLeod Julie
Published: April 2011

The struggling second and third graders in this mixed methods study increased their reading comprehension after a 10‐week Readers Theatre podcasting project. Podcasting made the students aware of a wider audience, which enhanced the authenticity and social nature of the strategy, and made their performances permanent so they could be stored and conveniently retrieved for later listening and evaluation. Finally, students discussed their podcasts using visual vocabulary such as “watch,” “show,” “look good,” and “show my voice,” uncovering the concept of audio as a visual medium. Since visualization is a critical strategy used by skilled readers, podcasting has the potential to strengthen this aspect of Readers Theatre.
Differentiated Coaching: Fostering Reflection With Teachers
Authors: Stover Katie , Kissel Brian , Haag Karen , Shoniker Rebecca
Published: April 2011

Literacy coaches inspire teacher reflection and promote a culture of ongoing professional learning. This article illustrates the role of literacy coaches, describes how coaches differentiate support for a diverse group of teachers, and explains how teacher reflection can be a catalyst for change and professional growth. The authors, current and former coaches themselves, describe their experiences and show how their work met the varied needs of individual teachers. They suggest tools coaches can use to differentiate within the practice and describe how they used daybooks, surveys, and videotaping to foster teacher reflection. Furthermore, the authors examine how an awareness of reflection occurs during differentiated coaching.
Integrating Writing and Mathematics
Authors: Wilcox Brad , Monroe Eula Ewing
Published: April 2011

Teachers often find it difficult to integrate writing and mathematics while honoring the integrity of both disciplines. In this article, the authors present two levels of integration that teachers may use as a starting point. The first level, writing without revision, can be worked into mathematics instruction quickly and readily. The second level, writing with revision, may take more time but enables teachers to connect the writing process more fully with mathematics instruction. Six examples are provided, including student work, in which teachers have successfully attended to the goals of both writing and mathematics.
Transcending the Curricular Barrier Between Fitness and Reading With FitLit
Authors: Opitz Michael F.
Published: April 2011

The author discusses how FitLit, children's literature that spotlights the multiple aspects of health and well‐being, offers a vehicle for integrating reading and fitness into existing classroom routines such as guided reading, read‐alouds, independent reading, and reading and writing workshop. Sample FitLit titles are provided as well as a detailed lesson to show how fitness and reading can be integrated within the school day and how students can be encouraged to apply their learning in their everyday lives for optimal fitness and reading.
Using Sheep to Control Purple Loosestrife (Lythrum salicaria)
Authors: Kleppel G. S. , LaBarge Erin
Published: April 2011

We investigated the use of sheep for controlling the spread of purple loosestrife in a wet meadow in upstate New York from June to August 2008. Changes in the purple loosestrife population and vascular plant community structure were monitored as a function of the grazing of two ewes, “rotated” through four “experimental” paddocks at 2- to 3-d intervals. Comparative data were collected in “reference” paddocks from which sheep were excluded. Purple loosestrife was heavily grazed and most plants did not flower in experimental paddocks. Purple loosestrife cover declined by 40.7% in the experimental paddocks but did not change significantly in the reference paddocks. After grazing, species richness was 20% higher in experimental than reference paddocks.
Tamarisk (Tamarixspp.) Establishment in its Most Northern Range
Authors: Lehnhoff Erik A. , Menalled Fabian D. , Rew Lisa J.
Published: April 2011

Tamarisk, a shrub or small tree native to Eurasia, was introduced to North America in the early 1800s and is now naturalized throughout many riparian areas of the southwestern United States, where extensive research has been conducted. It is a more recent invader to the northern Great Plains, and fewer studies have been conducted on tamarisk ecology and management in this area. The objectives of this research were to investigate the overwintering potential of tamarisk seeds in Montana and the relationship between hydrologic conditions and historic tamarisk establishment. Emergence of seedlings from seeds stored for different time periods at a range of temperatures was evaluated in a greenhouse study. Emergence rates declined after a 7-d storage period, but storage time had no effect on subsequent emergence rates, and seeds stored at −14 C and 5 C had greater emergence rates than those stored at 20 C and 35 C. Patterns in tamarisk establishment were assessed through age and hydrologic data collected from a reservoir (Fort Peck), a regulated river (Bighorn), and an unregulated river (Yellowstone) in Montana. These data indicated that tamarisk establishment at the reservoir was closely related to historic water levels, whereas establishment on rivers was not related to flow. However, data from the rivers indicated that recruitment differed between regulated and unregulated rivers, with the regulated river having less recruitment after the period of initial colonization than the unregulated river. Our results show that tamarisk seeds have the ability to overwinter in Montana and can establish under a range of flow conditions, indicating potential recolonization of sites after tamarisk removal.
Interactions between Two Biological Control Agents and an Herbicide for Canada Thistle (Cirsium arvense) Suppression
Authors: Sciegienka Joanna K. , Keren Elai N. , Menalled Fabian D.
Published: April 2011

We investigated the single and combined effects of two biological control agents, the stem-mining weevilHadroplontus lituraand the pathogenPseudomonas syringaepv.tagetis, with a herbicide (reduced or full application of glyphosate: 0.63 kg ae ha−1, or 3.78 kg ae ha−1, respectively) on the growth of Canada thistle,Cirsium arvense. We hypothesized that first, although each control method would have a negative effect on Canada thistle shoot biomass, root biomass, and shoot number, the integration of more than one control method would have greater impact than individual control methods. Second, we hypothesized that the order in which control methods are applied affects the outcome of the management program, with a pathogen application following weevil infestation being more effective than one prior to it. Although control methods impacted Canada thistle growth (P < 0.001, expect for a nonsignificant impact of glyphosate on shoot number), the combined effect of the three control methods behaved, generally, in an additive manner. A marginal interaction between the pathogen and the herbicide (P = 0.052) indicated a slight antagonistic interaction between these control methods. An interaction between the two biological control agents tested (P < 0.001) indicated that application of a pathogen prior to the release of weevil larvae could be more deleterious to Canada thistle than a late application. The observed, mostly additive, relationship between biological control agents and herbicides implies that integrating control methods rather than using a single approach could lead to greater Canada thistle control.
Patient-Reported Outcomes in a Phase III Study of Everolimus Versus Placebo in Patients with Metastatic Carcinoma of the Kidney That Has Progressed on Vascular Endothelial Growth Factor Receptor Tyrosine Kinase Inhibitor Therapy
Authors: Beaumont Jennifer L. , Butt Zeeshan , Baladi Jeanfrancois , Motzer Robert J. , Haas Tomas , Hollaender Norbert , Kay Andrea , Cella David
Published: April 2011

Purpose.

A phase III, randomized, double-blind, placebo-controlled trial was conducted in patients with metastatic renal cell carcinoma. The focus of this paper is to evaluate the patient-reported outcomes.

Methods.

Patients were randomly assigned (2:1) to receive oral everolimus 10 mg once daily or placebo. The Functional Assessment of Cancer Therapy Kidney Symptom Index—Disease-Related Symptoms (FKSI-DRS) and European Organization for the Research and Treatment of Cancer (EORTC) QLQ-C30 were administered before randomization and on day 1 of each cycle. The FKSI-DRS and the EORTC QLQ-C30 Physical Functioning and Global Quality of Life scores were the primary endpoints examined. Longitudinal models were used to compare treatment arms. Sensitivity analyses were conducted to explore the impact of missing data assumptions.

Results.

Longitudinal trends for FKSI-DRS scores did not differ by treatment arm. Taking nonignorable missing data into account, there were significant differences between treatment arms in the trend over time for physical functioning and global quality of life, with the everolimus arm exhibiting greater decreases. All three of these measures of health-related quality of life were significantly related to progression-free survival.

Conclusions.

There was no evidence of a difference between everolimus and placebo in longitudinal patterns of disease-related symptoms, and little difference between the arms in physical functioning or global quality of life trends. This supports the conclusion that delay in tumor progression demonstrated by everolimus is associated with minimal impact on symptoms, physical functioning, or quality of life, as reported by patients.
Becoming Other-Wise: A Story Of A Collaborative And Narrative Approach To Art Therapy With Two Indigenous Kids ‘In Care’
Authors: Linnell Sheridan
Published: April 2011

This chapter engages with the question of working with ‘the Other’, and especially with those who are Othered by colonialism, through an account of therapeutic work with two Indigenous Australian children who have been removed from their families of origin. As a non-Indigenous art therapist working in collaboration with an Indigenous community worker and carer, I consider this experience in the context of past histories and present-day effects and practices of colonisation, in particular the legacies of Australia's Stolen Generation. The chapter is framed by a commentary from the Indigenous worker and carer, since collaboration and consultation are just as central to the methodology of writing this account as to the therapeutic work itself. Within this frame, I offer a series of tellings and retellings, and engage with how visual art can gesture toward the unspeakable. I take up poetry as an alternative form of enquiry to the genre of the case study, in order to shape a poetics as well as a politics of therapeutic practice. I consider how this work, and writing about this work, has brought my dominant professional identity and practice into question and engaged me in becoming Other-wise. I begin with the words of Galiindurra, followed by a poem I wrote for the family.
Moleculars Mechanisms for the Synthesis and Genetic Regulation of Long- Chain Polyunsaturated Fatty Acids
Authors: Rodriguez-Cruz Maricela
Published: April 2011

Essential fatty acids—linoleic and linolenic—are metabolized to long-chain polyunsaturated fatty acids
(LC-PUFAs) such as arachidonic acid (AA) and eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA),
respectively, throughout a series of desaturation and elongation steps. LC-PUFAs are essential for a variety of
physiological functions including brain development, cardiac function, inflammatory response, and homeostasis.
These roles at the cellular level include modulation of signal transduction via effect of bioactive cell membranes
and by regulating the expression of a wide array of genes through different transcription factors such as
peroxisome proliferator-activated receptors (PPARs), sterol regulatory-element binding protein (SREBP),
carbohydrate response-element binding protein (ChREBP) and nuclear factor κB (NFκB) mainly to control the
transcription of target genes including those encoding proteins involved with lipid and carbohydrate metabolism,
thermogenesis, and cell differentiation. However, more work is required to delineate these actions and to have a
better understanding of the beneficial role of LC-PUFAs in order to comprehend the action of these fatty acids in
the pathogenesis of various diseases. Integrative analysis including nutritional, biochemical, genetic and
immunological studies may provide information about the identification of specific molecular mechanisms
involved in the beneficial effects of n3 LC-PUFAs such as DHA and EPA intake and their metabolic derivates on
health promotion or disease burden.
Role of Long-Chain Polyunsaturated Fatty Acids in Pregnancy and Lactation: Fetal and Infant Growth
Authors: Rodriguez-Cruz Maricela
Published: April 2011

The purpose of this review is to provide an overview regarding the role of ω-3 and ω-6 long-chain
polyunsaturated fatty acids (LC-PUFAs), arachidonic acid (AA) and docosahexaenoic acid (DHA) on normal
growth and maturation of the central nervous system and retina of the fetus, newborn and infant. Numerous
studies have shown that DHA is associated with higher scores on tests of visual and neural development in infants
and children. We also present progress concerning the molecular mechanism triggered during pregnancy and
lactation to support LC-PUFAs requirements. During pregnancy, the fetus demands LC-PUFAs, which are
provided through placental transfer. Placental transfer of fatty acids involves a multi-step process of uptake and
translocation facilitated by specific proteins that favor DHA and AA over other fatty acids. After birth, the
newborn acquires the LC-PUFAs from milk or formula. LC-PUFAs from cord blood and breast milk are acquired
from the maternal diet, mobilized from reserves, or synthesized de novo in the maternal organism from the
precursors linoleic acid (LA) and linolenic acid (LNA). The mother adapts her metabolism to support this
draining of LC-PUFAs through mammary tissue, using a high rate of dietary uptake and allowing the expression
of enzymes responsible for LC-PUFAs synthesis. We have demonstrated that mammary tissue, together with the
liver, plays an important role in the synthesis of ω-3 and ω-6 LC-PUFAs to supply to the product in pregnancy
and lactation.