bluuebunny/crossref_metadata_2025 huggingface dataset:
Coastal conditions
Authors: Platt Christopher , Pert Alan , Murray Gordon
Published: March 2012

Houses are fascinating because they seem to occupy a pivotal position in the spectrum of human construction. They are, perhaps, located right on the watershed between what is generally understood as ‘architecture’ and what is considered as just ‘building’. They allow us to probe the very definition of what architecture is perceived to be. Using the typology of the dwelling - and three examples from three architectural practices - we examine differing responses to context, climate and the vernacular, documenting and evaluating commonalities and differentials in design approaches. The examples are a holiday home in Dungeness by NORD, an artists’ residence and studio on Loch Fyne by GMA and a house on the Isle of Lewis by studioKAP.
Living in the field: ethnographic experience of place
Authors: Kellett Peter
Published: March 2012

In our daily life we draw heavily on our experiential interpretations of the places we inhabit through our work and domestic lives. Such understandings draw directly from the senses and our bodily engagement in space. In contrast, our analyses and interpretations of the places and sites of others often rely on a different range of skills in which ‘objectivity’ is privileged over personal responses. Such approaches usually rely on short visits in which hard ‘factual’ and visual data is collected quickly. Rarely in architectural or urban studies do researchers live ‘in the field’. This contrasts markedly with anthropology where time spent living in the field is regarded as essential, and such ethnographic studies gain credence and credibility through long periods of residence.
The field and the table: Rosalind Krauss's ‘expanded field’ and the Anarchitecture group
Authors: Walker Stephen
Published: March 2012

The Anarchitecture group emerged in the early 1970s in New York. Although it has become somewhat synonymous with the work of Gordon Matta-Clark, it had a broad membership of equally significant artists, including Laurie Anderson, Tina Girouard, Carol Goodden, Suzanne Harris, Jene Highstein, Bernard Kirschenbaun, Richard Landry and Richard Nonas among others. Philip Ursprung's recent catalogue essay sets out some of the complexities that accompany any attempt to understand the group's internal dynamic, and the problematic conflation of its collective activities to the work, or at least to the ideas, of Matta-Clark.
The use and interpretation of serum retinol distributions in evaluating the public health impact of vitamin A programmes
Authors: Palmer Amanda C , West Keith P , Dalmiya Nita , Schultink Werner
Published: March 2012

Objective

Developing countries have adopted universal, high-potency vitamin A (VA) supplementation and food fortification as major strategies to control deficiency, prevent nutritional blindness and reduce child mortality. Yet questions persist regarding how best to measure impact and when to phase out supplementation. The present paper provides guidance on the use and interpretation of serum retinol (SROL) distributions as indicators of both programme impact and adequate VA intake in a population.

Design

We reviewed extant data on SROL's response to high-potency VA supplementation and VA-fortified foods in children.

Results

Supplementation virtually eliminates xerophthalmia and reduces child mortality; however, it shifts the SROL distribution only transiently (<2 months). Regular consumption of VA-fortified foods prevents xerophthalmia, lowers mortality and sustainably improves SROL distributions, from which both compliance and public health impact can be inferred.

Conclusions

Given SROL's limited responsiveness to high-potency VA supplementation, target population coverage remains the preferred performance indicator. However, periodic SROL surveys do reflect underlying dietary risk and can guide programming: low or marginal SROL distributions in areas with high supplementation coverage do not signify programme failure, but rather suggest the need to continue supplementation while working to effectively raise dietary VA intakes. We propose that a sustained rise in the SROL distribution, defined as ≤5 % prevalence of SROL < 0·70 μmol/l among vulnerable population groups in at least two consecutive surveys (≥1 year apart), be used as an indicator of stable and adequate dietary VA intake and status in a population, at which point programmes may re-evaluate the need for continued universal supplementation.
Introduction: Exploring Parent Abuse – Building Knowledge across Disciplines
Authors: Hunter Caroline , Nixon Judy
Published: March 2012

There is an extensive body of literature on the ways in which the family home is often a site of conflict and discord rather than security and safety. Much of this work has focussed on the problem of domestic violence perpetrated by adults and how the state should respond to it (Home Office, 2009). Another form of family violence however, that of the abuse of parents (or those occupying a parental role) by their adolescent children, has not received such public (or academic) recognition (Hunteret al., 2010). In the UK, the issue of parent abuse remains one of the most unacknowledged and under-researched form of family violence.
Some Useful Sources
Authors: Hunter Caroline , Nixon Judy
Published: March 2012

The following list provides a brief overview of relevant publications on parent abuse, together with links to some useful websites. Given the nature of parent abuse the publications come from a varied disciplinary background ranging from the therapeutic to social policy and criminological. Some look at the nature and incidence of parent abuse, some examine the experience and causes of it, while others suggest therapeutic interventions. See further the discussion by Holt, this volume.
Primary production and carbon export rates across the subpolar N. Atlantic Ocean basin based on triple oxygen isotope and dissolved O2 and Ar gas measurements
Authors: Quay P. , Stutsman J. , Steinhoff T.
Published: March 2012

Gross photosynthetic O2 production (GOP) rates in the subpolar North Atlantic Ocean were estimated using the measured isotopic composition of dissolved oxygen in the surface layer on samples collected on nine transits of a container ship between Great Britain and Canada during March 2007 to June 2008. The mean basin‐wide GOP rate of 226 ± 48 mmol O2 m−2 d−1 during summer was double the winter rate of 107 ± 41 mmol O2 m−2 d−1. Converting these GOP rates to equivalent 14C‐based PP (14C‐PPeqv) yielded rates of 1005 ± 216 and 476 ± 183 mg C m−2 d−1 in summer and winter, respectively, that generally agreed well with previous 14C‐based PP estimates in the region. The 14C‐PPeqv estimates were 1–1.6× concurrent satellite‐based PP estimates along the cruise track. A net community production rate (NCP) of 87 ± 12 mmol O2 m−2 d−1 (62 ± 9 mmol C m−2 d−1) and NCP/GOP of 0.35 ± 0.06 in the mixed layer was estimated from O2/Ar and 17Δ measurements (61°N 26°W) during spring bloom conditions in May 2008. Contrastingly, a much lower long‐term annual mean NCP or organic carbon export rate of 2.8 ± 2.7 mol C m−2 yr−1 (8 ± 7 mmol C m−2 d−1) and NCP/GOP of 0.07 ± 0.06 at the winter mixed layer depth was estimated from 15 years of surface O2 data in the subpolar N. Atlantic collected during the CARINA program.
Two spacecraft observations of magnetic discontinuities in the solar wind with STEREO
Authors: Malaspina David M. , Gosling J. T.
Published: March 2012

Directional discontinuities in the solar wind magnetic field are often explored by either single‐spacecraft studies with tens of thousands of events or multiple‐spacecraft studies with between ten and a few hundred events. The unique orbits of the twin STEREO spacecraft afford the opportunity for a multiple‐spacecraft study of tens of thousands of directional discontinuities at variable spacecraft separation. Automated algorithms are developed both for identifying magnetic directional discontinuities at a single spacecraft and for matching discontinuities between spacecraft. Four months of data yield tens of thousands of discontinuities per spacecraft and several thousand discontinuities identified at both spacecraft. Rates of occurrence, minimum lengths, and aspect ratios are determined for discontinuities identified at both spacecraft. Distributions of directional discontinuity properties, including thickness, normal vector orientation, waiting times between successive discontinuities, and the angle through which the magnetic field rotates while crossing the discontinuity (shear angle), are determined for directional discontinuities observed at both spacecraft as well as those observed at only a single spacecraft. It is found that the distributions of many of these properties are different between directional discontinuities observed by both spacecraft and those observed by only a single spacecraft. Based on the nature of these differences, the population of discontinuities observed by both spacecraft is most consistently interpreted as the walls of solar wind flux tubes.
Eddy covariance measurements of the sea spray aerosol flux over the open ocean
Authors: Norris Sarah J. , Brooks Ian M. , Hill Martin K. , Brooks Barbara J. , Smith Michael H. , Sproson David A. J.
Published: March 2012

Direct eddy covariance measurements of size‐segregated sea spray aerosol fluxes over the open Atlantic Ocean are presented, along with a source function derived from them for a wind speed range of 4 to 18 m s−1 and a size range of 0.176 < R80 < 6.61 μm. This is in broad agreement with other recent estimates of the source function over this size range but shows a more rapid decrease with size above R80 = 2 μm than most other functions. The measurements were made during a 3 week cruise in the North Atlantic as part of the UK contribution to the international Surface Ocean–Lower Atmosphere Study (SOLAS) program. They utilized the new high‐rate Compact Lightweight Aerosol Spectrometer Probe (CLASP), providing a 16‐channel size spectrum (0.17 <Ramb < 9.5 μm) at 10 Hz, collocated with a sonic anemometer. The measurements demonstrate the high variability in sea spray aerosol flux compared with other air‐sea fluxes, both between individual estimates and in the scales contributing to the flux.
In situ observations of volcanic ash clouds from the FAAM aircraft during the eruption of Eyjafjallajökull in 2010
Authors: Johnson Ben , Turnbull Kate , Brown Phil , Burgess Rachel , Dorsey James , Baran Anthony J. , Webster Helen , Haywood Jim , Cotton Richard , Ulanowski Z. , Hesse Evelyn , Woolley Alan , Rosenberg Philip
Published: March 2012

During April–May 2010 the UK Facility for Airborne Atmospheric Measurements (FAAM) BAe‐146 aircraft flew 12 flights targeting volcanic ash clouds around the UK. The aircraft observed ash layers between altitudes of 2–8 km with peak mass concentrations typically between 200–2000μg/m3, as estimated from a Cloud and Aerosol Spectrometer (CAS). A peak value of 2000–5000 μg/m3 was observed over Scotland on 14 May 2010, although with considerable uncertainty due to the possible contamination by ice. Aerosol size distributions within ash clouds showed a fine mode (0.1–0.6 μm) associated with sulphuric acid and/or sulphate, and a coarse mode (0.6–35 μm) associated with ash. The ash mass was dominated by particles in the size range 1–10 μm (volume‐equivalent diameter), with a peak typically around 3–5μm. Electron‐microscope images and scattering patterns from the SID‐2H (Small Ice Detector) probe showed the highly irregular shape of the ash particles. Ash clouds were also accompanied by elevated levels of SO2 (10–100 ppbv), strong aerosol scattering (50–500 × 10−6 m−1), and low Ångstrom exponents (−0.5 to 0.4) from the 3‐wavelength nephelometer. Coarse‐mode mass specific aerosol extinction coefficients (kext), based on the CAS size distribution varied from 0.45–1.06 m2/g. A representative value of 0.6 m2/g is suggested for distal ash clouds (∼1000 km downwind) from this eruption.
Statistics for orbital neutron spectroscopy of the Moon and other airless planetary bodies
Authors: Miller R. S.
Published: March 2012

A rigorous statistical approach is presented to address the shortcomings inherent in the analysis of counting experiments such as orbital neutron spectroscopy endeavors. Unlike the quasi‐Gaussian statistics commonly applied to such investigations, the methodology described here incorporates fundamental elements of Poisson statistics including its inherent nature as a bounded, discrete, and intrinsically asymmetric probability distribution. In addition, we utilize the proper statistical formulae required to describe the data following background subtraction. Utilizing the Likelihood Ratio Method for hypothesis testing, we find that analyses utilizing collimated instruments such as the Lunar Exploration Neutron Detector (LEND) aboard NASA's Lunar Reconnaissance Orbiter overestimate detection significances by
, under the assumption that collimator effectiveness as asserted by the LEND team is correct. This in turn implies that the required exposure times must be ∼2× longer to reach prelaunch sensitivity estimates. We provide updated estimates for hydrogen abundance sensitivity limits as a function of exposure time and compare the sensitivities of collimated (i.e., background subtracted) and uncollimated approaches.
Validation and comparison of two soil‐vegetation‐atmosphere transfer models for tropical Africa
Authors: Akkermans T. , Lauwaet D. , Demuzere M. , Vogel G. , Nouvellon Y. , Ardö J. , Caquet B. , De Grandcourt A. , Merbold L. , Kutsch W. , Van Lipzig N.
Published: March 2012

This study aims to compare and validate two soil‐vegetation‐atmosphere‐transfer (SVAT) schemes: TERRA‐ML and the Community Land Model (CLM). Both SVAT schemes are run in standalone mode (decoupled from an atmospheric model) and forced with meteorological in‐situ measurements obtained at several tropical African sites. Model performance is quantified by comparing simulated sensible and latent heat fluxes with eddy‐covariance measurements. Our analysis indicates that the Community Land Model corresponds more closely to the micrometeorological observations, reflecting the advantages of the higher model complexity and physical realism. Deficiencies in TERRA‐ML are addressed and its performance is improved: (1) adjusting input data (root depth) to region‐specific values (tropical evergreen forest) resolves dry‐season underestimation of evapotranspiration; (2) adjusting the leaf area index and albedo (depending on hard‐coded model constants) resolves overestimations of both latent and sensible heat fluxes; and (3) an unrealistic flux partitioning caused by overestimated superficial water contents is reduced by adjusting the hydraulic conductivity parameterization. CLM is by default more versatile in its global application on different vegetation types and climates. On the other hand, with its lower degree of complexity, TERRA‐ML is much less computationally demanding, which leads to faster calculation times in a coupled climate simulation.
Non‐apoptotic functions of apoptosis‐regulatory proteins
Authors: Galluzzi Lorenzo , Kepp Oliver , Trojel‐Hansen Christina , Kroemer Guido
Published: March 2012

During the past two decades, apoptotic cell death has been the subject of an intense wave of investigation, leading to the discovery of multiple gene products that govern both its induction and execution. In parallel, it has progressively become evident that most, if not all, proteins that had initially been discovered for their essential role in apoptosis also mediate a wide range of non‐apoptotic functions. On the one hand, apoptotic regulators and executioners are involved in non‐lethal physiological processes as diverse as cell cycle progression, differentiation, metabolism, autophagy and inflammation. On the other hand, pro‐apoptotic proteins can control other modalities of programmed cell death, in particular regulated necrosis. In this review, we summarize the unconventional roles of the apoptotic core machinery from a functional perspective and discuss their pathophysiological implications.EMBO reports advance online publication 9 March 2012; doi:10.1038/embor.2012.19
Lysine methylation of FOXO3 regulates oxidative stress‐induced neuronal cell death
Authors: Xie Qi , Hao Yumin , Tao Li , Peng Shengyi , Rao Chitong , Chen Hong , You Han , Dong Meng‐qiu , Yuan Zengqiang
Published: March 2012

FOXO transcription factors have a critical role in oxidative stress‐induced neuronal cell death. A variety of post‐translational modifications of FOXO family proteins have been reported, including phosphorylation, acetylation, ubiqutination and recently arginine methylation. Here, we demonstrate that the methyltransferase Set9 methylates FOXO3 at lysine 270. Methylation of FOXO3 leads to the inhibition of its DNA‐binding activity and transactivation. Accordingly, lysine methylation reduces oxidative stress‐induced and FOXO3‐mediated Bim expression and neuronal apoptosis in neurons. Collectively, these findings define a novel modification of FOXO3 and show that lysine methylation negatively regulates FOXO3‐mediated transcription and neuronal apoptosis.
Shapes of supramolecular cages by ion mobility mass spectrometry
Authors: Ujma Jakub , De Cecco Martin , Chepelin Oleg , Levene Hannah , Moffat Chris , Pike Sarah J. , Lusby Paul J. , Barran Perdita E.
Published: March 2012

Ion mobility mass spectrometry distinguishes between isobaric supramolecular complexes, revealing subtle structural differences and their effect on the stability of self assembled architectures.
Acoustofluidics 9: Modelling and applications of planar resonant devices for acoustic particle manipulation
Authors: Glynne-Jones Peter , Boltryk Rosemary J. , Hill Martyn
Published: March 2012

This article discusses the design, construction and applications of planar resonant devices for acoustic manipulation of particles and cells.
Critical Evaluation of Mouse Models Used to Study Pain and Loss of Pain Perception in Diabetic Neuropathy
Authors: Bierhaus A. , Nawroth P.
Published: March 2012

A number of studies have addressed diabetic neuropathy (DN) in transgenic and knock out mouse models to unravel the molecular mechanisms underlying metabolic pain and loss of pain perception. However, it is difficult to compare these studies with each other or even with human DN due to experimental differences including the type of diabetes, the background strain of the respective mouse model, the methods of diabetes induction and the duration of diabetes, animal age and gender. To receive useful information for DN from genetically modified mice, it is therefore mandatory to first define the appropriate model and – if necessary – to backcross transgenic strains into the respective background to allow a reliable (and at least in part translatable to human DN) interpretation of the results.
Understanding Diabetic Polyneuropathy and Longevity: What Can We Learn from the Nematode Caenorhabditis Elegans?
Authors: Mendler M. , Schlotterer A. , Morcos M. , Nawroth P.
Published: March 2012

Pathogenesis of late diabetic complications is influenced by a complex interplay of multiple exogenous and intrinsic factors. The well characterised nematode Caenorhabditis elegans is an ideal model to study causes of diabetic polyneuropathy because of its easily accessible nervous system. A repertoire of methods allows the assessment of both morphological and functional glucotoxic damages as well as reduction of lifespan, thereby helping to examine the influence of different pathways and mechanisms on neurodegeneration. Its insulin signalling system allows to directly visualize effects of insulin on high glucose induced neuronal damage, leading to a better understanding of diabetic polyneuropathy.
Crosstalk in the Retinal Neurovascular Unit – Lessons for the Diabetic Retina
Authors: Feng Y. , Busch S. , Gretz N. , Hoffmann S. , Hammes H.-P.
Published: March 2012

Diabetic retinopathy shares important features with neurodegenerative retinal diseases, including loss of ganglion cells and retinal thinning. The impact on vasoregression and subsequent ischemia-driven changes such as macular edema and proliferative retinopathy are not established. Studies using adult neurodegenerative animal models such as the transgenic TGR(CMV-PKD2(1/703)HA) rat imply early activation of the innate immunity system and the complement system as well as microglia playing a role in the damage of the retinal neurovascular unit.
Macrovascular Disease in Diabetes: Is the Mouse a Suitable Model?
Authors: Müller O. , Katus H. , Backs J.
Published: March 2012

To elucidate the pathogenesis of macrovascular disease in diabetes, animal models are widely used. Diabetic mice are of particular interest because they can be crossed to knockout mice lacking specific genes that are under consideration to contribute to diabetic vascular complications. However, the mouse is relative resistant to develop atherosclerosis. Therefore, we review some commonly used mouse models and discuss their advantages and disadvantages.
Capped L1-ordered FePt granular media with reduced surface roughness
Authors: Takekuma I. , Nemoto H. , Matsumoto H. , Ito S. , Sayama J. , Hirotsune A. , Hirayama Y.
Published: March 2012

L10-ordered FePtAg-C granular media capped with an FePtAg-SiO2 layer were fabricated in order to obtain stable flyability performance on a spin-stand tester. The post-annealed FePtAg-SiO2 was more suitable for the cap layer than an FePt alloy without segregants, since it formed a continuous structure on the well-isolated FePtAg-C layer. By using the optimized post-annealed FePtAg-SiO2 capped medium, the surface roughness (Ra) was reduced to 0.45 nm, thereby enabling stable flying at a glide height of 6 nm.
Anomalous behavior of high-frequency zero-field ferromagnetic resonance in aluminum-substituted ɛ-Fe2O3
Authors: Yoshikiyo Marie , Namai Asuka , Nakajima Makoto , Suemoto Tohru , Ohkoshi Shin-ichi
Published: March 2012

In this work, we studied the temperature dependence of millimeter wave absorption due to natural resonance, zero-field ferromagnetic resonance, in ɛ-Al0.06Fe1.94O3. The natural resonance frequency (fr) was recorded at a high value of 172 GHz at room temperature. With decreasing temperature, the fr value gradually increased to 186 GHz (204 K) and then decreased to 147 GHz (77 K). At a very low temperature (21 K), the fr value was 133 GHz. This temperature dependence of fr corresponds to that of the coercive field (Hc), i.e., Hc = 19.4 kOe (300 K) → 22.6 kOe (200 K) → 5.7 kOe (90 K). The temperature region of the sigmoid decrease of fr almost corresponds to the temperature range of the spin reorientation. As for the linewidth of natural resonance, the full width at half maximum value (Δf) increased from 5 GHz (301 K) to 19 GHz (77 K). The temperature region of the sigmoid increase of Δf also corresponds to that of the spin reorientation. These fr and Δf anomalous temperature dependencies in ɛ-Al0.06Fe1.94O3 are understood by the disappearance of magnetic anisotropy due to spin reorientation phenomenon.
Energy-level alignment at the Alq3/Fe3O4(001) interface
Authors: Pratt A. , Dunne L. , Sun X. , Kurahashi M. , Yamauchi Y.
Published: March 2012

We have used the technique of metastable de-excitation spectroscopy to probe the interfacial electronic structure of the organic semiconductor (OSC) Alq3 deposited onto clean Fe3O4(001) substrates. We have measured shifts in the low-energy secondary electron cutoff and energetic onset of the highest occupied molecular orbital (HOMO) of Alq3 as the coverage increases from the sub-ML range to multilayer formation. We find that the presence of an interfacial dipole induces a uniform decrease in the valence band electronic states by 1.2 eV with respect to the vacuum level and modifies the position of the HOMO energetic onset to 1.8 eV below the substrate Fermi level. The strong intrinsic dipole moment of Alq3 is suggested as the origin for these changes in accordance with previous studies of Alq3 deposited onto various substrates.
Multipole expansion technique for the magnetostatic field computation in patterned magnetic films
Authors: Manzin A. , Bottauscio O.
Published: March 2012

This paper deals with the calculation of the magnetostatic field in magnetic antidot arrays with variable hole size. Boundary effects are taken into account by considering films with finite size, without introducing infinite periodicity assumption. To speed-up the computation, a macroscale grid with resolution equal to the spatial period is overlapped to the microscopic one, approximating the long-range contributions by a multipole expansion technique. Accuracy and efficiency are evaluated by varying the extension of the near-interaction zone and the expansion order.
Design and testing of piezoelectric energy harvester for powering wireless sensors of electric line monitoring system
Authors: Qiu Jing , Wen Yumei , Li Ping , Yang Jin
Published: March 2012

Scavenging electromagnetic and vibration energy from environments is an attractive technique for powering wireless sensors in a wireless sensor network. This paper reports our design and testing results on the electric output performance of a piezoelectric energy harvesting device, which consists of cantilever beams, magnetoelectric (ME) transducers, and permanent magnets. The geometric parameters of the device are based on an optimization design with a targeted resonant frequency of 50 Hz. Experimental results show that an output voltage of 56.1 V and an average power of 0.24 mW are achieved responding to a current of 3 A at 50 Hz. Remarkably, this power is a very encouraging power figure that gives the prospect of being able to power a wide range of wireless sensors in an electric line monitoring system.
Synthesis, structure, and magnetic properties of M(N3)2(bpy)
Authors: Danilović Dušan , Hamida Youcef , Lin C. L. , Yuen Tan , Li Kunhao , Li Jing
Published: March 2012

Powder crystalline metal-organic frameworks (MOF), M(N3)2(bpy) (where M = Ni, Co, Cu, and bpy = 4,4′-bipyridine), were successfully synthesized by mixing M(II) salts with solutions of 4,4′-bipyridine and NaN3. All three MOFs crystallize in an orthorhombic crystal system with the space group Cmmm (No. 65), which is isostructural to that of 2D-Fe(N3)2(bpy). The M(II) ions are coordinated with four azide ligands (N3) in equatorial plane forming linear magnetic chains. Isothermal magnetization, magnetic susceptibility, and heat capacity measurements were performed. No clear phase transitions were observed. The intra-chain magnetic interaction was found to be ferromagnetic for the Co and Ni compounds, and antiferromagnetic for the Cu compound. The data were fit to theoretical models, and the variation in the exchange interactions was interpreted in terms of the geometric distortions on the octahedral M(II) sites.
Spin-dependent tunneling spectroscopy in MgO-based double-barrier magnetic tunnel junctions
Authors: Yu G. Q. , Kurt H. , Feng J. F. , XU K. , Coey J. M. D. , Han X. F.
Published: March 2012

We investigated the dynamic conductance and inelastic electron tunneling spectroscopy in MgO-based double barrier magnetic tunnel junctions with Co50Fe50/Co40Fe40B20 hybrid free layers. The tunneling is coherent through the MgO (001) barriers but nonresonant, and the highest tunneling magnetoresistance reaches 260% at 2 K. Based on the detailed discussion of the tunneling mechanisms, the double-barrier junctions investigated here can be considered as two single-barrier junctions in series.
The strong quasi-one-dimensional antiferromagnetism in a charge-transfer insulator: AgSO4
Authors: Zhang Xiaoli , Jia Ting , Liu Ting , Zeng Zhi , Lin H. Q.
Published: March 2012

The strong quasi-one-dimensional antiferromagnetism and the electronic structure of AgSO4 are investigated by performing the first-principles density functional calculations. The results show that the strong quasi-one-dimensional antiferromagnetic coupling in AgSO4 is along [11¯1] diagonal of the unit cell. The superexchange interaction between the Ag1 4dx12-y12 and the Ag2 4dx22-y22 orbitals gives rise to the unusual strong quasi-one-dimensional antiferromagnetic behavior. We also found that AgSO4 is a charge-transfer insulator.
Spin transport in ferromagnet/semiconductor/ferromagnet structures with cubic Dresselhaus spin-orbit-interaction
Authors: Kondo Kenji
Published: March 2012

We have investigated the spin transport in ferromagnet (FM)/semiconductor (SC)/ferromagnet (FM) structures with a central SC barrier region exhibiting cubic Dresselhaus spin-orbit-interaction (SOI). The energy profile of the barrier is assumed to be a square with height V and thickness d along z-direction. The magnetoresistance (MR) ratio has been calculated for three different barriers, GaAs, GaSb, and GaAs without SOI as a function of barrier thickness. We have found that the MR ratio has a negative value for GaAs barrier with SOI except for very thin barrier thickness. In the case of GaSb barrier, the MR ratio changes sign from negative to positive with increasing the barrier thickness. Also, we have calculated the MR ratio with changing the spin coupling constant.
Size and phase control of cobalt–carbide nanoparticles using OH− and Cl− anions in a polyol process
Authors: Huba Zachary J. , Carpenter Everett E.
Published: March 2012

Exchange coupled cobalt–carbide nanocomposites and single-phase Co2C nanoparticles were synthesized using the polyol process. Hydroxide and chloride anions were used to control carbide phase and particle shape. Synthesized CoxC nanocomposites exhibited average diameters around 300 nm. CoxC nanocomposites synthesized at 0.25 M [OH−] and [Cl−] formed clusters of capped nanorods, whereas synthesis at 0.37 M [OH−] and [Cl−] produced clusters of long blade-like particles. For single-phase Co2C, an [OH−] and [Cl−] of 0.71 M was used and produced clusters of ellipsoidal grains. The CoxC nanocomposites comprised of capped nanorods possessed a BHmax of 1.65 MGOe with a magnetic saturation and coercivity values of 38 emu/g and 2.4 kOe, respectively. Co2C possessed a saturation magnetization of 16 emu/g and coercivity of 1.3 kOe.
Thermal artifact on the spin Seebeck effect in metallic thin films deposited on MgO substrates
Authors: Bosu S. , Sakuraba Y. , Uchida K. , Saito K. , Kobayashi W. , Saitoh E. , Takanashi K.
Published: March 2012

Spin Seebeck effect (SSE) was investigated in Heusler compound Co2MnSi (CMS) and ferromagnetic binary alloy Ni80Fe20 (Py) thin films deposited on MgO substrates at different ambient temperatures, T = 30 K to 295 K, by maintaining a finite temperature gradient along the film plane. Low temperature enhancement of voltage signal and a peak around T = 70 K were detected in a Pt wire placed on the higher temperature end of CMS (or Py) film. It has been found that the low temperature enhancement was dominated by a thermal artifact, which was generated by the anomalous Nernst effect with an additional perpendicular temperature gradient across the film plane. The remarkable mismatch between thermal conductivities of MgO and CMS (or Py) at low temperatures is considered to give rise to the perpendicular temperature gradient causing the thermal artifact. We showed that consideration of thermal conductivity matching between thin film and substrate is essential for performing experiments of SSE correctly; moreover, the observation of SSE could be realized only when minimization of the thermal artifact is possible.
Giant magneto-impedance effect of thin magnetic wires at elevated frequencies
Authors: Zhukov A. , Ipatov M. , Zhukova V.
Published: March 2012

In this paper, we present the results on giant magneto-impedance (GMI) effect in thin microwires at frequencies until 4 GHz, paying special attention to tailoring the GMI effect and achievement of low hysteretic GMI behavior. Correlation between magnetoelastic anisotropy and magnetic field dependences of diagonal and off-diagonal impedance components are observed. We found that, if the surface anisotropy is not circumferential, then the magnetization and, consequently, the magnetic field dependence of impendence present hysteresis. Low field GMI hysteresis, has been suppressed by the bias current.
The concept and fabrication of exchange switchable trilayer of FePt/FeRh/FeCo with reduced switching field
Authors: Zhou T. J. , Cher K. , Hu J. F. , Yuan Z. M. , Liu B.
Published: March 2012

We report the concept and fabrication of exchange switchable trilayer of FePt/FeRh/FeCo with reduced switching field for heat assisted magnetic recording (HAMR). A thin layer of FeRh is sandwiched between L10 FePt and magnetically soft FeCo. At room temperature, FePt and FeCo are magnetically isolated by the antiferromagnetic FeRh layer. After the metamagnetic transition of FeRh layer by heating, FePt and FeCo are exchange-coupled together through ferromagnetic FeRh layer. Therefore, the switching field of FePt can be greatly reduced via exchange-spring effect. Simulation work was carried out to understand the exchange coupling strength and the FeCo thickness effects on the switching field reduction. It is found that switching field decreases with the increase of exchange coupling strength and FeCo thickness. The trilayer films were also successfully fabricated. A clear change of reversal mechanism from two-step to one-step switching upon heating was observed and a 3-time switching field reduction was demonstrated. The results show the promise of the trilayer for HAMR applications.
Shifting the operating frequency of magnetoelectric sensors
Authors: Petrie Jonathan , Gray David , Viehland Dwight , Sreenivasulu Gollapudi , Srinivasan Gopalan , Mandal Sanjay , Edelstein Alan S.
Published: March 2012

A method is presented for increasing the operating frequency of symmetric and asymmetric magnetoelectric (ME) sensors so that the operating frequency can be equal to the mechanical resonance frequency of the sensor. This increase improves the signal to noise ratio of a symmetric sensor by at least two orders of magnitude because it mitigates the effect of 1/f noise and the sensor has an increased response at its resonant frequency. The method is based on the strong, nonlinear magnetic field dependence of the magnetostriction. Our method has lowered the detection limit to 4 pT/Hz at 1 Hz in a magnetically unshielded environment.
Spin dynamics in the multiferroic materials (invited)
Authors: Ye Feng , Fishman Randy S. , Haraldsen Jason , Lorenz Bernd , Chu C. W. , Kimura Tsuyoshi
Published: March 2012

We report high resolution inelastic neutron scattering measurements and spin dynamics calculations in two multiferroic materials: the geometrically frustrated triangular lattice CuFeO2 and mineral Hübnerite MnWO4. In un-doped CuFeO2 a low-T collinear spin structure is stabilized by long range magnetic interactions. When doped with a few percent of gallium, the spin order evolves into a complex noncollinear configuration and the system becomes multiferroic. Similarly, the ground state collinear spin order in pure MnWO4 results from delicate balance between competing magnetic interactions up to 11th nearest neighbors and can be tuned by substitution of Mn ions with magnetic or nonmagnetic impurities. The comprehensive investigation of spin dynamics in both systems help to understand the fundamental physical process and the interactions leading to the close interplay of magnetism and ferroelectricity in this type of materials.
Piezoelectric properties of epitaxial Pb(Zr0.525, Ti0.475)O3 films on amorphous magnetic metal substrates
Authors: Hu B. , Chen Y. , Yang A. , Gillete S. , Fitchorov Trifon , Geiler A. , Daigle A. , Su X. D. , Wang Z. , Viehland D. , Vittoria C. , Harris V. G
Published: March 2012

Epitaxial growth of high piezoelectric constant Pb(Zr0.525, Ti0.475)O3 (PZT) thin films deposited on amorphous magnetic Metglas® substrates by pulsed laser deposition (PLD) is reported. Particularly, Pt or Au buffer layers were employed to initiate epitaxial growth of the PZT films from atop of an amorphous surface. The optimization of deposition conditions for the PZT films with different buffer layers was systematically investigated. The crystal structure, texturing, and surface morphology of the samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Ferroelectric and piezoelectric properties were measured indicating high polarization 27 μC/cm2 and piezoelectric constant d33, 46 pm/V for the Pt buffered films. The PZT thin films grown on a magnetostrictive material have demonstrated high quality crystallographic structure and piezoelectric response, having potential for use in emerging magnetoelectric sensors.
Structure and properties of epitaxial perovskite Pb(Zr0.52Ti0.48)O3/La0.7Sr0.3MnO3 heterostructures
Authors: Zou Cheng , Chen Yuan-Fu , Li Ping-Jian , Fan Rui , Peng Bing , Zhang Wen-Xu , Wang Ze-Gao , Hao Xin , Liu Jing-Bo , Zhang Wan-Li , Li Yan-Rong , Li Run-Wei
Published: March 2012

The morphology, crystalline structure of epitaxial heterostructures of Pb(Zr0.52Ti0.48)O3/La0.7Sr0.3MnO3 (PZT/LSMO) grown on single crystalline SrTiO3 substrates by pulse laser deposition (PLD), have been investigated. The morphology results show that the LSMO layers and PZT layers are smooth and homogenous. The crystalline structure measurements indicate that good epitaxial relationships between LSMO and PZT and STO were obtained. The effects of applied electric and magnetic fields on the physical properties of epitaxial perovskite ferroelectric/ferromagnetic heterostructures were investigated. The results show that the polarized electric field has a very significant influence on the transport properties of LSMO layers while has little influence on the magnetization, and the magnetic field has an obvious influence on the ferroelectric behavior of the PZT layer.
Magnetic properties of Mn-implanted 6H-SiC single crystal
Authors: Al Azri M. , Elzain M. , Bouziane K. , Chérif S. M. , Roussigné Y. , Declemy A. , Drouet M. , Thomé L.
Published: March 2012

The electronic and magnetic structures of Mn-doped 6H-SiC have been investigated using ab initio calculations. Various configurations of Mn sites and vacancy types have been considered. The calculations showed that a substitutional Mn atom at either Si or C sites possesses a magnetic moment. The Mn atom at Si site possesses larger magnetic moment than Mn atom at C site. The magnetic properties of ferromagnetically and antiferromagnetically coupled pair of Mn atoms in the presence of vacancies have also been explored. Our calculations show that antiferromagnetically coupled pair of Mn atoms at Si sites with neighboring C vacancy is magnetically more stable. Relaxation effects were also studied. The results are correlated to the measured magnetic properties obtained for Mn-implanted 6H-SiC for various Mn concentrations.
Analytical analysis and implementation of a low-speed high-torque permanent magnet vernier in-wheel motor for electric vehicle
Authors: Li Jiangui , Wang Junhua , Zhigang Zhao , Yan Weili
Published: March 2012

In this paper, analytical analysis of the permanent magnet vernier (PMV) is presented. The key is to analytically solve the governing Laplacian/quasi-Poissonian field equations in the motor regions. By using the time-stepping finite element method, the analytical method is verified. Hence, the performances of the PMV machine are quantitatively compared with that of the analytical results. The analytical results agree well with the finite element method results. Finally, the experimental results are given to further show the validity of the analysis.
Investigation on the antiferromagnetic component in the intrinsic exchange bias in structurally single phase Cr2Te3 thin film
Authors: Hui Lu , Lim S. T. , Bi J. F. , Teo K. L.
Published: March 2012

We report the intrinsic exchange bias in structurally single phase Cr2Te3 thin film grown by low temperature molecular beam epitaxy. The hysteresis loop shift is confirmed due to the ferromagnet/antiferromagnet coupling rather than surface spin disorder effect or minor loop effect. The AFM component attributing to the exchange bias stems from the vacancy Cr layer in Cr2Te3 and is of two dimensions. The magnetic properties of the AFM component are investigated by studying the temperature dependence and the measure field dependence of coercivity and hysteresis loop shift. The blocking temperature is determined to be about 110 K. It is found that the two dimensional AFM component would lose its irreversibility for larger applied measure field.
Si/NiFe seed layers for Ru intermediate layer in perpendicular magnetic recording tape media
Authors: Saemma Gaku , Takahashi Shota , Matsunuma Satoshi , Inoue Tetsutaro , Nakagawa Shigeki
Published: March 2012

Si/NiFe seed layers prepared at room temperature is effective to attain better c-axis orientation of Ru intermediate layer in the FeCoB/Ru/CoPtCr-SiO2 granular type recording tape media. The crystallinity and c-axis orientation of Ru layer with Si/NiFe seed layers were improved than that without Si/NiFe seed layer deposited on the laminated FeCoB SULs. When the Ru is thicker than 8 nm, Δθ50 of the CoPtCr-SiO2 recording layer shows small value of about 6.5°. Furthermore, even though the Ru thickness was only 3 nm, the Δθ50 retained comparatively small value of 8.0°. Si/NiFe layer is effective as a seed layer for the Ru intermediate layer.
Correlation between microstructure and electromagnetic properties in magnetic tunnel junctions with naturally oxidized MgO barrier
Authors: Yoshida Chikako , Ochiai Takao , Sugii Toshihiro
Published: March 2012

We investigated the correlation between the microstructure and the electromagnetic properties of magnetic tunnel junctions (MTJs) with MgO barriers fabricated by direct sputtering and natural oxidation of the Mg layers. The MTJ with an oxidized Mg barrier contained amorphous phases in both the barrier and the CoFeB free layer and exhibited large interface fluctuations in both the CoFeB reference/MgO and MgO/CoFeB interfaces This had a significant influence on the low MR ratio and large switching current. Inserting a CoFe seed layer under the oxidized Mg barrier greatly improved the crystallization of the oxidized MgO which ultimately led to a higher MR ratio and lower switching current. In addition to the textured CoFeB/MgO/CoFeB structures, the sharp interface of the MgO barrier, low B content in the MgO barrier, and Fe-rich composition in the free layer are thought to be of key importance for ensuring high magneto-transport properties.
Origins of axial inhomogeneity of magnetic performance in hot deformed Nd-Fe-B ring magnets
Authors: Yin Wen-Zong , Chen Ren-Jie , Tang Xu , Lin Min , Lee Don , Yan Aru
Published: March 2012

Hot-deformed Nd-Fe-B ring magnets have wide potential applications. These ring magnets, however, exhibit axial inhomogeneity of magnetic performance. In this work, the effects of density, pressure, deformation temperature, deformation rate, and texture on axial magnetic performance were investigated over ring magnets prepared by backward extrusion method. It was demonstrated that the texture accounted for the variation of magnetic performance along axial direction. Microstructures of the ring magnets were examined with SEM, which further revealed two different origins of axial inhomogeneity of magnetic performance. The deformation degree of Nd-Fe-B grains plays a critical role in the performance difference between the top and middle part of ring magnet. But that between the middle and bottom part mainly results from different alignment orientations of platelet Nd-Fe-B grains. It was both deformation degree and alignment orientation that determined the axial texture and consequent magnetic performance of hot-deformed ring magnets.
Two-dimensional numerical analysis of electroconvection in a dielectric liquid subjected to strong unipolar injection
Authors: Traoré Ph. , Pérez A. T.
Published: March 2012

Two-dimensional numerical simulations are carried out to examine the problem of transient electroconvection stability of dielectric liquids subjected to unipolar injection. The entire set of electrohydrodynamics equations associated with the electroconvective phenomena that occur in a layer of a dielectric liquid between two parallel electrodes subjected to a potential difference are solved numerically. We first validate the numerical simulation by comparing our linear stability electroconvection criteria with those obtained by other authors with a stability approach. In this paper, we restrict the study to the strong injection case, which corresponds to values of the non-dimensional injection parameter C greater than or equal to 10. The numerical solution of the electroconvective problem is then presented for rigid lateral boundary conditions. A detailed analysis of the scenario that occurs for different characteristic values of the stability parameter T is provided. The flow structure and its behaviour highlight the existence of different regimes, from laminar to chaotic. The development of charged plumes has been observed in particular. We compute the electrical Nusselt number for different values of the stability parameter and ion mobility. The electrical Nusselt number saturates with increasing T, a fact that it is in agreement with available experimental data. Finally, a spectral analysis is conducted for different aspect ratios of the computational domain. The spectral analysis gives an insight into the physical origin of the velocity and current oscillations.
Spin-spin and spin-orbit interactions in nanographene fragments: A quantum chemistry approach
Authors: Perumal S. , Minaev B. , Ågren H.
Published: March 2012

The relativistic behavior of graphene structures, starting from the fundamental building blocks – the poly-aromatic hydrocarbons (PAHs) along with other PAH nanographenes – is studied to quantify any associated intrinsic magnetism in the triplet (T) state and subsequently in the ground singlet (S) state with account of possible S-T mixture induced by spin-orbit coupling (SOC). We employ a first principle quantum chemical-based approach and density functional theory (DFT) for a systematic treatment of the spin-Hamiltonian by considering both the spin-orbit and spin-spin interactions as dependent on different numbers of benzene rings. We assess these relativistic spin-coupling phenomena in terms of splitting parameters which cause magnetic anisotropy in absence of external perturbations. Possible routes for changes in the couplings in terms of doping and defects are also simulated and discussed. Accounting for the artificial character of the broken-symmetry solutions for strong spin polarization of the so-called “singlet open-shell” ground state in zigzag graphene nanoribbons predicted by spin-unrestricted DFT approaches, we interpolate results from more sophisticated methods for the S-T gaps and spin-orbit coupling (SOC) integrals and find that these spin interactions become weak as function of size and increasing decoupling of electrons at the edges. This leads to reduced electron spin-spin interaction and hence almost negligible intrinsic magnetism in the carbon-based PAHs and carbon nanographene fragments. Our results are in agreement with the fact that direct experimental evidence of edge magnetism in pristine graphene has been reported so far. We support the notion that magnetism in graphene only can be ascribed to structural defects or impurities.