bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative analysis of saccharides by X‐ray photoelectron spectroscopy
Authors: Stevens Joanna S. , Schroeder Sven L. M.
Published: March 2009

A series of saccharides, including several monohydrates and one amorphous phase, has been investigated by XPS, providing the first database of survey and high‐resolution spectra for this class of compounds. Known stoichiometries and XPS‐determined elemental compositions agree well. XPS has sufficient precision for distinguishing the stoichiometries of mono‐, di‐, and polysaccharides. The C 1s chemical shifts of the acetal and alcohol groups are similar for all samples, albeit with slight binding energy increases in the series from mono‐ to di‐ and polysaccharides. Increasing X‐ray exposure causes a radiation‐induced increase of the aliphatic hydrocarbon emission at 285 eV, concomitant with the appearance of a high binding energy C 1s emission peak at 289.1 eV and a decrease in the O 1s/C 1s emission intensity ratio. Formation of aliphatic hydrocarbon groups is proposed to arise from dehydroxylation, while the increase in the 289.1 eV peak can be attributed to double dehydroxylation at the C1 position or partial oxidation of an alcohol or acetal group. The rate of radiation damage correlates with previously reported rates of thermally induced caramelization. Copyright © 2009 John Wiley & Sons, Ltd.
Residence Time Distribution Determination Using On‐Line Digital Image Processing
Authors: Lee Siew Yoong , Hanna Milford A. , Jones David D.
Published: March 2009

A less laborious, and non‐destructive on‐line digital image processing (DIP) technique was developed to measure the residence time distribution (RTD) in an extruder. The a* value of the L* a* b* color space coordinates was measured using DIP and compared to the value obtained by a colorimeter method. The R2 values showed a high correlation (R2 = 0.88) of a* values between both methods. The influence of screw configuration (compression and mixing screws) and barrel temperature (150 and 160ºC) on RTD were analyzed by the mean residence time (MRT) and variance for both methods. Mixing screws and lower temperature resulted in higher MRT and variance for both methods. The DIP method was faster and less subjected to human and experimental errors than traditional off‐line measurements.
Remedial Operation for Primary Hyperparathyroidism
Authors: Prescott Jason D. , Udelsman Robert
Published: March 2009

Background

Remedial surgery for patients with persistent or recurrent primary hyperparathyroidism (1° HPT) remains a significant challenge. Cervical reexploration is technically difficult; reoperative neck anatomy is distorted by fibrosis and, as a result, remedial 1° HPT patients carry an increased risk of injury to the recurrent (RLN) and superior laryngeal nerve(s) as well as to normal residual parathyroid tissue. Causative hyperfunctioning parathyroid tissue is also more frequently ectopic in the remedial setting and can thus be difficult to localize.

Methods

This report assimilates the current data underlying preoperative, intraoperative and postoperative remedial 1° HPT management and presents an evidence‐based algorithm for the management of remedial parathyroid disease. Recommendations are graded according to the quality of supporting data using the system initially developed by Sackett (Chest 95:2S–4S, 1989) and subsequently modified by Heinrich et al. (Ann Surg 243:154–168, 2006).

Results

Recent advances in preoperative localization and intraoperative adjuncts have lead to substantial improvements in outcomes after remedial surgery. Preoperative localization techniques, including sestamibi scintigraphy (MIBI), high resolution ultrasound (US), US‐guided fine needle aspiration (FNA) and selective venous sampling (SVS), coupled with intraoperative adjuncts such as the rapid parathyroid hormone (PTH) assay have lead to reoperative cure rates as high as 96 percent. Nonetheless, management of remedial 1° HPT varies significantly between surgeons and no formal recommendations standardizing the care of these patients have been published.

Conclusions

Despite the significant challenges associated with remedial surgery for 1° HPT, excellent outcomes can be reproducibly achieved when proper pre‐, intra‐, and postoperative management is employed.
New music in the Office of Thomas Becket from the Diocese of Trier
Authors: Joubert Estelle
Published: March 2009

This article examines aspects of variation and transmission in the Office of Thomas Becket in the Diocese of Trier, Germany. Palaeographic evidence suggests that by the mid-fifteenth century, liturgical sources in Trier exhibited numerous transmission errors and disruptions in the modal scheme of the Thomas Office. However, a subset of late fifteenth- and early sixteenth-century manuscripts from St Florin and St Castor in Koblenz displays efforts to restore the theoretical modal scheme of the Office by composing new melodies for four items; the uniqueness of these items has been confirmed with the assistance of a large-scale electronic project cataloguing the Office of Thomas Becket across Europe, headed by Andrew Hughes at the University of Toronto. The present study provides a detailed melodic and modal analysis of the four newly composed items: the invitatory, Adsunt Thome martyris; the fourth responsory for Matins, Post sex annos; the ninth responsory for Matins, Iesu bone per Thome; and the fourth antiphon for Lauds, Ad Thome memoriam. Numerous melodic allusions to the Office of St Gorgonius – a martyr also venerated in Koblenz from the turn of the fifteenth century – have been uncovered in the four newly composed items. The re-ordering of the modal schemes of the Thomas Office and the colourful array of musical and theological echoes and allusions between the Becket and Gorgonius Offices suggests a desire to establish, reflect and cultivate a local liturgical identity within the community in Koblenz.
A Transmission Electron Microscopy Study of Fe-Co Alloy Nanoparticles in Silica Aerogel Matrix Using HREM, EDX, and EELS
Authors: Falqui Andrea , Corrias Anna , Gass Mhairi , Mountjoy Gavin
Published: March 2009

Magnetic nanocomposite materials consisting of 5.5 wt% Fe-Co alloy nanoparticles in a silica aerogel matrix, with compositions FexCo1−x of x = 0.50 and 0.67, have been synthesized by the sol-gel method. The high-resolution transmission electron microscopy images show nanoparticles consisting of single crystal grains of body-centered cubic Fe-Co alloy, with typical crystal grain diameters of approximately 4 and 7 nm for Fe0.5Co0.5 and Fe0.67Co0.33 samples, respectively. The energy dispersive X-ray (EDX) spectra summed over areas of the samples gave compositions FexCo1−x with x = 0.48 ± 0.06 and 0.68 ± 0.05. The EDX spectra obtained with the 1.5 nm probe positioned at the centers of ∼20 nanoparticles gave slightly lower concentrations of Fe, with means of ⟨x⟩ = 0.43 ± 0.01 and ⟨x⟩ = 0.64 ± 0.02, respectively. The Fe0.5Co0.5 sample was studied using electron energy loss spectroscopy (EELS), and EELS spectra summed over whole nanoparticles gave x = 0.47 ± 0.06. The EELS spectra from analysis profiles of nanoparticles show a distribution of Fe and Co that is homogeneous, i.e., x = 0.5, within a precision of at best ±0.05 in x and ±0.4 nm in position. The present microscopy results have not shown the presence of a thin layer of iron oxide, but this might be at the limit of detectability of the methods.
Scanning Electron Microscopy and Synchrotron Radiation X-Ray Tomographic Microscopy of 330 Million Year Old Charcoalified Seed Fern Fertile Organs
Authors: Scott Andrew C. , Galtier Jean , Gostling Neil J. , Smith Selena Y. , Collinson Margaret E. , Stampanoni Marco , Marone Federica , Donoghue Philip C.J. , Bengtson Stefan
Published: March 2009

Abundant charcoalified seed fern (pteridosperm) pollen organs and ovules have been recovered from Late Viséan (Mississippian 330 Ma) limestones from Kingswood, Fife, Scotland. To overcome limitations of data collection from these tiny, sometimes unique, fossils, we have combined low vacuum scanning electron microscopy on uncoated specimens with backscatter detector and synchrotron radiation X-ray tomographic microscopy utilizing the Materials Science and TOMCAT beamlines at the Swiss Light Source of the Paul Scherrer Institut. In combination these techniques improve upon traditional cellulose acetate peel sectioning because they enable study of external morphology and internal anatomy in multiple planes of section on a single specimen that is retained intact. The pollen organMelissiothecashows a basal parenchymatous cushion bearing more than 100 sporangia on the distal face. Digital sections show the occurrence of pollen in some sporangia. The described ovule is new and has eight integumentary lobes that are covered in spirally arranged glandular hairs. Virtual longitudinal sections reveal the lobes are free above the pollen chamber. Results are applied in taxonomy and will subsequently contribute to our understanding of the former diversity and evolution of ovules, seeds, and pollen organs in the seed ferns, the first seed-bearing plants to conquer the land.
Toward Reproducible Three-Dimensional Microstructure Analysis of Granular Materials and Complex Suspensions
Authors: Holzer Lorenz , Münch Beat
Published: March 2009

Focused ion beam nanotomography (FIB-nt) is a novel method for high resolution three-dimensional (3D) imaging. In this investigation we assess the methodological parameters related to image acquisition and data processing that are critical for obtaining reproducible microstructural results from granular materials and from complex suspensions. For this purpose three case studies are performed: (1) The precision of FIB-nt is evaluated by analyzing a reference sample with nanospheres. Due to the implementation of an automated correction procedure, drift phenomena can be removed largely from the FIB data. However, at high magnifications remaining drift components can induce problems for 3D-shape reconstructions. (2) Correct object recognition from densely packed microstructures requires specific algorithms for splitting of agglomerated particles. To establish quantitative criteria for the correct degree of splitting, a parametric study with dry portland cement is performed. It is shown that splitting with a k-value of 0.6 leads to accurate results. (3) Finally, the reproducibility of the entire cryo-FIB analysis is investigated for high pressure frozen cement suspensions. Reproducible analyses can be obtained if the magnification is adapted to the particle size. At low magnifications the small particles and their surface area are underestimated. At high magnifications representativity is questioned because local inhomogeneities can become dominant.
Chemical Shift of Electron Energy-Loss Near-Edge Structure on the Nitrogen K-Edge and Titanium L3-Edge at TiN/Ti Interface
Authors: Terada Shohei , Asayama Kyoichiro , Tsujimoto Masahiko , Kurata Hiroki , Isoda Seiji
Published: March 2009

We investigated the chemical shift of the electron energy-loss near-edge structure (ELNES) for the nitrogen K-edge and titanium L3-edge measured from the interface region between a titanium nitride layer and a titanium layer. Both the titanium nitride and titanium layers were prepared by a sputtering method. Elemental analysis for nitride and titanium in the vicinity of the interface region was performed using a standard technique in electron energy-loss spectroscopy. It was demonstrated that both the ELNES of nitrogen K-edge and titanium L3-edge presented the chemical shift, more or less, depending on the composition of TiNx. The experimental findings were interpreted using a first-principles band structure calculation. The chemical shifts of nitrogen K-edge and titanium L3-edge can be used as fingerprinting for readily distinguishing the composition of TiNx.
Next 50 years of space research
Authors: Bonnet R.-M.
Published: March 2009

Forecasting the next 50 years of space research is a dangerous game and a somewhat irresponsible action. Fortunately, the past 50 years have evidenced what remains in the realm of realism and of the feasible and what definitely belongs to the realm of utopia. Nevertheless those who, like me today, take the risk of forecasting such a relatively long time trend are sure of one thing: to be wrong!
The maximum magnetic flux in an active region
Authors: Livadiotis George , Moussas Xenophon
Published: March 2009

The Photometric-Magnetic Dynamical model handles the evolution of an individual sunspot as an autonomous nonlinear, though integrable, dynamical system. The model considers the simultaneous interplay of two different interacted factors: The photometric and magnetic factors, respectively, characterizing the evolution of the sunspot visible area A on the photosphere, and the simultaneous evolution of the sunspot magnetic field strength B. All the possible sunspots are gathered in a specific region of the phase space (A, B). The separatrix of this phase space region determines the upper limit of the values of sunspot area and magnetic strength. Consequently, an upper limit of the magnetic flux in an active region is also determined, found to be ≈7.23 × 1023 Mx. This value is phenomenologically equal to the magnetic flux concentrated in the totality of the granules of the quite Sun. Hence, the magnetic flux concentrated in an active region cannot exceed the one concentrated in the whole photosphere.
The mid-term periodicities in sunspot areas
Authors: Getko Ryszarda
Published: March 2009

The sunspot area fluctuations for the northern and the southern hemispheres of the Sun over the epoch of 12 cycles (12–23) are investigated. Because of the asymmetry of their probability distributions, the positive and the negative fluctuations are considered separately. The auto-correlation analysis of them shows three quasi-periodicities at 10, 17 and 23 solar rotations. The wavelets gives the 10-rotation quasi-periodicity. For the original and the negative fluctuations the correlation coefficient between the wavelet and the auto-correlation results is about 0.9 for 90% of the auto-correlation peaks. For the positive fluctuations it is also 0.9 for 70% of the peaks. For 90% of cycles in both hemispheres the auto-correlation analysis of negative fluctuations shows that two longer periods can be represented as the multiple of the shortest period. For positive fluctuations such dependences are found for more than 50% of cases.
Determining the full halo coronal mass ejection characteristics
Authors: Fainshtein V. G.
Published: March 2009

In this paper we determined the parameters of 45 full halo coronal mass ejections (HCMEs) for various modifications of their cone forms (“ice cream cone models”). We show that the CME determined characteristics depend significantly on the CME chosen form. We show that, regardless of the CME chosen form, the trajectory of practically all the considered HCMEs deviate from the radial direction to the Sun-to-Earth axis at the initial stage of their movement.
Major solar flares without coronal mass ejections
Authors: Gopalswamy N. , Akiyama S. , Yashiro S.
Published: March 2009

We examine the source properties of X-class soft X-ray flares that were not associated with coronal mass ejections (CMEs). All the flares were associated with intense microwave bursts implying the production of high energy electrons. However, most (85%) of the flares were not associated with metric type III bursts, even though open field lines existed in all but two of the active regions. The X-class flares seem to be truly confined because there was no material ejection (thermal or nonthermal) away from the flaring region into space.
Re-examining the correlation of complex solar type III radio bursts and solar energetic particles
Authors: MacDowall R. J. , Richardson I. G. , Hess R. A. , Thejappa G.
Published: March 2009

Interplanetary radio observations provide important information on particle acceleration processes at the Sun and propagation of the accelerated particles in the solar wind. Cane et al. (2002) have drawn attention to a class of prominent radio bursts that accompany >20 MeV solar proton events. They call these bursts ‘type III-L’ because: they are fast drifting (like normal type III bursts associated with electrons accelerated at impulsive solar flares); they are Long-lasting compared to normal type III bursts; they occur Late compared to the onset of the related solar event; and, they commence at Lower frequencies (~100 MHz) than normal type III bursts, suggesting that they originate higher in the corona at ~0.5 Rs above the Sun. We report on an analysis of the correlated radio and SEP events during 1996-2006 using the Wind Waves and near-Earth SEP data sets, and discuss whether the characteristics of the complex type III bursts (at less than 14 MHz) will permit them to serve as proxies for SEP event occurrence and intensity.
Magnetic reconnection in the heliosphere: new insights from observations in the solar wind
Authors: Gosling J. T.
Published: March 2009

Magnetic reconnection plays a central role in the interpretation of a wide variety of observed solar, space, astrophysical, and laboratory plasma phenomena. The relatively recent discovery that reconnection is common at thin current sheets in the solar wind opens up a new laboratory for studying this fundamental plasma process and its after-effects. Here we provide a brief overview of some of the new insights on reconnection derived from observations of reconnection exhaust jets in the solar wind.
Forbush effects and their connection with solar, interplanetary and geomagnetic phenomena
Authors: Belov A. V.
Published: March 2009

Forbush decrease (or, in a broader sense, Forbush effect) - is a storm in cosmic rays, which is a part of heliospheric storm and very often observed simultaneously with a geomagnetic storm. Disturbances in the solar wind, magnetosphere and cosmic rays are closely interrelated and caused by the same active processes on the Sun. Thus, it is natural and useful to investigate them together. Such an investigation in the present work is based on the characteristics of cosmic rays with rigidity of 10 GV. The results are derived using data from the world wide neutron monitor network and are combined with relevant information into a data base on Forbush effects and large interplanetary disturbances.
Bootstrap energization of relativistic electrons in magnetized plasmas
Authors: Roth Ilan
Published: March 2009

In situ and remote observations indicate that relativistic or ultra relativistic electrons are formed at various magnetized configurations. It is suggested that a specific bootstrap mechanism operates in some of these environments. The mechanism applies to (a) relativistic electrons observed on localized field lines in outer radiation belt - through a process initiated at a distant substorm injection; (b) relativistic electrons observed at the interplanetary medium - through a process initiated via coronal injection, at large distances from flares or propagating CME; (c) ultra-relativistic electrons deduced at the galactic jets - through a process initiated via local injection at the small-scale magnetic field. The injected nonisotropic electrons excite whistler waves which boost efficiently the tail of the electron distribution.
Simulations of shock structures of a flare/CME event in the low corona
Authors: Pomoell Jens , Vainio Rami , Pohjolainen Silja
Published: March 2009

We study the MHD processes related to a flare/CME event in the lower solar corona using numerical simulations. Our initial state is an isothermal gravitationally stratified corona with an embedded flux rope magnetic field structure. The eruption is driven by applying an artificial force to the flux rope. The results show that as the flux rope rises, a shock structure is formed, reaching from ahead of the flux rope all the way to the solar surface. The speed of the shock quickly exceeds that of the driving flux rope, and the shock escapes from the driver. Thus, the shock exhibits characteristics both of the driven and blast wave type. In addition, the temperature distribution behind the shock is loop-like, implying that erupting loop-like structures observed in soft X-ray images might be shocks. Finally, we note that care must be taken when performing correlation analysis of the speed and location of type II bursts and ejecta.
Properties of dayside outer zone chorus during HILDCAA events: Loss of energetic electrons
Authors: Tsurutani Bruce T. , Verkhoglyadova Olga P. , Lakhina Gurbax S. , Yagitani Satoshi
Published: March 2009

The dayside outer zone (DOZ) portion of the magnetosphere is a region where chorus intensities are statistically found to be the most intense. In this study, DOZ chorus have been examined using OGO‐5 plasma wave and GEOTAIL plasma wave, magnetic field and energetic particle data. Dayside chorus is noted to be composed of ∼0.1 to 0.5 s rising‐tone emissions called “elements.” The duration of the elements and their frequency‐time characteristics are repeatable throughout the chorus event (lasting from tens of minutes to hours), but may differ from event to event. Chorus is a right‐hand, circularly polarized electromagnetic plane wave. Waves are detected propagating from along the ambient magnetic field, Bo, to oblique angles near the Gendrin angle, θGendrin. All waves, independent of wave direction of propagation relative to Bo, are found to be circularly polarized, to first order. Chorus rising‐tone elements are composed of coherent “subelements” or “packets” with durations of ∼5 to 10 ms. Consecutive subelements/packets step in frequency with time to form the elements. The peak amplitudes within a packet can be ∼0.2 nT or greater. The subelement or packet amplitudes are at least an order of magnitude larger than previously estimated chorus amplitudes obtained by power spectral measurements. This discrepancy is due to the presence of interspacings between chorus elements, the interspacings between subelements/packets within an element, and the different frequencies of subelements/packets within a rising‐tone. DOZ chorus studied here were found to be consistent with generation via the loss cone instability of substorm‐injected temperature‐anisotropic (/ > 1) E = 5 to 40 keV electrons drifting from the midnight sector to the DOZ region. Using a large amplitude subelement/packet wave magnetic field amplitude of ∼0.2 nT, it is shown that the instantaneous Kennel‐Petschek pitch angle diffusion rate Dαα is ∼5 × 10−2 s−1. This latter quantity is based on incoherent waves. If energetic electrons stay in cyclotron resonance throughout their interaction with a coherent subelement of duration 10 ms, they may be “pitch angle transported” by ∼5°. Therefore electrons within 5° of the loss cone can be lost in a single wave‐particle interaction. Several such interactions as the electrons traverse the wave region can lead to much larger pitch angle transport angles. The similar time‐scales of chorus elements and bremsstrahlung X‐ray microbursts (∼0.5 s) can be explained by the “pitch angle transport” mechanism described above. Increasing and decreasing pitch angle transport via this mechanism will lead to much higher pitch angle diffusion or “super diffusion” rates. Isotropic unpolarized noise of ∼20 pT peak amplitude has also been detected. The noise is well above instrument noise levels and is speculated to be remnants of chorus or hiss.
Objective estimates of westward Rossby wave and eddy propagation from sea surface height analyses
Authors: Barron C. N. , Kara A. B. , Jacobs G. A.
Published: March 2009

An objective method to estimate westward propagation of sea surface height (SSH) anomalies is introduced and compared to a subjective technique. Both approaches use time series extracted from global SSH analyses, prepared by optimal interpolation of altimeter data, as described in detail. The cost function used in the objective method calculates the mean along‐slope standard deviation, where slope is the reciprocal of propagation speed and defines the angle of linear samples through the SSH time series along each transect. The along‐slope standard deviation can be computed as an extension of the Radon transform, as shown. The optimum speed estimate minimizes the cost function, and speeds with mean along‐slope standard deviation within 1% of the minimum define the range of uncertainty. The 1% criteria was chosen to give a seemingly reasonable uncertainty range over a variety of cases and does not imply a specific probability that the true minimum is bounded in the uncertainty range. Applied in the central Pacific, objective speed estimates increase from 1 cm s−1 or less at the highest latitudes to above 30 cm s−1 nearer the equator. Subjective speed estimates are similar to, but generally lower than, their objective counterparts, reflecting a bias in subjective interpretation that is likely to vary among different individuals. A more detailed examination of the along‐slope minimization over 160°E–95°W focuses on the higher low‐latitude speeds, returning estimates of 48 cm s−1 (45 cm s−1) at 5.5°N (5.5°S) over 1993–2006. The corresponding 42–55 cm s−1 (38–65 cm s−1) uncertainty ranges bound most of the predictions from sensitivity test cases with alternate preprocessing filters or different multiyear time windows, although variability is larger south of the equator. The findings are consistent with prior studies and suggest the methods may be useful for other applications over the global ocean.
Venus cloud top winds from tracking UV features in Venus Monitoring Camera images
Authors: Moissl R. , Khatuntsev I. , Limaye S. S. , Titov D. V. , Markiewicz W. J. , Ignatiev N. I. , Roatsch T. , Matz K.‐D. , Jaumann R. , Almeida M. , Portyankina G. , Behnke T. , Hviid S. F.
Published: March 2009

To date dynamical observations of the Venus clouds have delivered mainly either only short‐term or long‐term averaged results. With the Venus Monitoring Camera (VMC) it finally became possible to investigate the global dynamics with a relatively high resolution in space and time on a long‐term basis. Our findings from manual cloud feature wind tracking in VMC UV image sequences so far show that the details of the mesospheric dynamics of Venus appear to be highly variable. Although the general rotation of the atmosphere remained relatively stable since Mariner 10, more than 30 years ago, by now, there are indications of short‐term variations in the general circulation pattern of the Venus atmosphere at cloud top level. In some cases, significant variations in the zonal wind properties occur on a timescale of days. In other cases, we see rather stable conditions over one atmospheric revolution, or longer, at cloud top level. It remains an interesting question whether the irregularly observed midlatitude jets are indeed variable or simply become shielded from view by higher H2SO4 haze layers for varying time intervals. Winds at latitudes higher than 60°S are still difficult to obtain track because of low contrast and scarcity of features but increasing data is being collected. Over all, it was possible to extend latitudinal coverage of the cloud top winds with VMC observations. Thermal tides seem to be present in the data, but final confirmation still depends on synthesis of Visible and Infrared Thermal Imaging Spectrometer and VMC observations on night and dayside. Although poorly resolved, meridional wind speed measurements agree mainly with previous observations and with the presence of a Hadley cell spanning between equatorial region and about 45°S latitude.
A new method for attributing climate variations over the Atlantic Hurricane Basin's main development region
Authors: Zhang Rong , Delworth Thomas L.
Published: March 2009

We propose a new approach to decompose observed climate variations over the Atlantic Hurricane Basin's main development region (MDR) into components attributable to radiative forcing changes and to internal oceanic variability. Our attribution suggests that the observed multidecadal anomalies of vertical shear (Uz) and a simple index of maximum potential intensity (SIMPI) for tropical cyclones are both dominated by internal variability, consistent with multidecadal variations of Atlantic Hurricane activity; changes in radiative forcing led to increasing Uz and decreasing SIMPI since the late 50's, unfavorable for Atlantic Hurricane activity. Physically, at least for the GFDL model, sea surface temperature (SST) anomalies induced by ocean heat transport variations are more efficient in producing negative Uz anomalies than that induced by altered radiative forcing.
AMP-activated protein kinase pathway: a potential therapeutic target in cardiometabolic disease
Authors: Wong Aaron K. F. , Howie Jacqueline , Petrie John R. , Lang Chim C.
Published: March 2009

AMPK (AMP-activated protein kinase) is a heterotrimetric enzyme that is expressed in many tissues, including the heart and vasculature, and plays a central role in the regulation of energy homoeostasis. It is activated in response to stresses that lead to an increase in the cellular AMP/ATP ratio caused either by inhibition of ATP production (i.e. anoxia or ischaemia) or by accelerating ATP consumption (i.e. muscle contraction or fasting). In the heart, AMPK activity increases during ischaemia and functions to sustain ATP, cardiac function and myocardial viability. There is increasing evidence that AMPK is implicated in the pathophysiology of cardiovascular and metabolic diseases. A principle mode of AMPK activation is phosphorylation by upstream kinases [e.g. LKB1 and CaMK (Ca2+/calmodulin-dependent protein kinase], which leads to direct effects on tissues and phosphorylation of various downstream kinases [e.g. eEF2 (eukaryotic elongation factor 2) kinase and p70 S6 kinase]. These upstream and downstream kinases of AMPK have fundamental roles in glucose metabolism, fatty acid oxidation, protein synthesis and tumour suppression; consequently, they have been implicated in cardiac ischaemia, arrhythmias and hypertrophy. Recent mechanistic studies have shown that AMPK has an important role in the mechanism of action of MF (metformin), TDZs (thiazolinediones) and statins. Increased understanding of the beneficial effects of AMPK activation provides the rationale for targeting AMPK in the development of new therapeutic strategies for cardiometabolic disease.
Role of regulatory T-cells in autoimmunity
Authors: Mellanby Richard J. , Thomas David C. , Lamb Jonathan
Published: March 2009

There has been considerable historical interest in the concept of a specialist T-cell subset which suppresses over-zealous or inappropriate T-cell responses. However, it was not until the discovery that CD4+CD25+ T-cells had suppressive capabilities both in vitro and in vivo that this concept regained credibility and developed into one of the most active research areas in immunology today. The notion that in healthy individuals there is a subset of Treg-cells (regulatory T-cells) involved in ‘policing’ the immune system has led to the intensive exploration of the role of this subset in disease resulting in a number of studies concluding that a quantitative or qualitative decline in Treg-cells is an important part of the breakdown in self-tolerance leading to the development of autoimmune diseases. Although Treg-cells have subsequently been widely postulated to represent a potential immunotherapy option for patients with autoimmune disease, several studies of autoimmune disorders have demonstrated high numbers of Treg-cells in inflamed tissue. The present review highlights the need to consider a range of other factors which may be impairing Treg-cell function when considering the mechanisms involved in the breakdown of self-tolerance rather than focussing on intrinsic Treg-cell factors.
Characterization of high-k HfO2 films prepared using chemically modified alkoxy-derived solutions
Authors: Suzuki Kazuyuki , Kato Kazumi
Published: March 2009

The HfO2 films were prepared using alkoxy-derived precursor solutions. The effects of the chemical composition of precursor solutions on the microstructure development and electrical properties were investigated. The flatness and refractive index of the HfO2 films were improved by using diethanolamine-added solution. This result is considered to be due to the difference in the progress of organic decomposition and the behavior of nucleation and grain growth. The difference in the chemical composition affected the electrical properties such as leakage current and capacitance-voltage characteristics, which are related to the defects in the film and interface state.
First principles investigation of defect energy levels at semiconductor-oxide interfaces: Oxygen vacancies and hydrogen interstitials in the Si–SiO2–HfO2 stack
Authors: Broqvist Peter , Alkauskas Audrius , Godet Julien , Pasquarello Alfredo
Published: March 2009

We introduce a scheme for the calculation of band offsets and defect energy levels at semiconductor-oxide interfaces. Our scheme is based on the use of realistic atomistic models of the interface structure and of hybrid functionals for the evaluation of the electronic structure. This scheme is herein applied to the technologically relevant Si–SiO2–HfO2 stack. Calculated band offsets show a very good agreement with experimental values. In particular, we focus on the energy levels of the oxygen vacancy defect and the interstitial hydrogen impurity. The defect levels are aligned with respect to the interface band structure and determined for varying location in the dielectric stack. The most stable charge states are identified as the Fermi level sweeps through the silicon band gap.
Highly uniform resistive switching characteristics of TiN/ZrO2/Pt memory devices
Authors: Sun B. , Liu Y. X. , Liu L. F. , Xu N. , Wang Y. , Liu X. Y. , Han R. Q. , Kang J. F.
Published: March 2009

We fabricated the TiN/ZrO2/Pt sandwiched resistive switching memory devices. Excellent bipolar resistive switching characteristics, including a large number of switching cycles and highly uniform switching parameters, as well as long retention time were achieved. The improved switching behavior of TiN/ZrO2/Pt could be attributed to the oxygen reservoir effect of TiN electrodes on the formation and rupture of the filamentary conducting paths by modifying the concentration distributions of the oxygen ions and vacancies in ZrO2 thin films. The results demonstrate the feasibility of high performance resistive switching memory devices based on transition metal oxides by using TiN as the top electrode.
Fabrication and characterization of metal-ferroelectric (PbZr0.6Ti0.4O3)-insulator (La2O3)-semiconductor capacitors for nonvolatile memory applications
Authors: Juan Trevor Pi-Chun , Lin Cheng-Li , Shih Wen-Chieh , Yang Chin-Chieh , Lee Joseph Ya-Min , Shye Der-Chi , Lu Jong-Hong
Published: March 2009

Metal-ferroelectric-insulator-semiconductor thin-film capacitors with Pb(Zr0.6,Ti0.4)O3 (PZT) ferroelectric layer and high-k lanthanum oxide (La2O3) insulator layer were fabricated. The outdiffusion of atoms between La2O3 and silicon was examined by the secondary-ion-mass spectroscopy. The size of memory window as a function of PZT annealing temperature was discussed. The maximum memory window saturated to 0.7 V, which is close to the theoretical memory window ΔW≈2dfEc≈0.8 V with higher annealing temperatures above 700 °C. The memory window starts to decrease due to charge injection when the sweep voltage is higher than 5 V at 600 °C-annealed samples. The C-V flatband voltage shift (ΔVFB) as a function of charge injection was characterized in this work. An energy band diagram of the Al/PZT//La2O3/p-Si system was proposed to explain the memory window and the flatband voltage shift.
Magnetoelectric study in Terfenol-D/Tb2(MoO4)3 bilayer composite
Authors: Peng Song , Yang Pan , Cai Wei , Lu Xiaomei , Liu Junming , Yan Feng , Xu Min , Zhang Huaijin , Wang Jiyang , Zhu Jinsong
Published: March 2009

The dependence of the magnetoelectric coefficients (αE) in the Terfenol-D/Tb2(MoO4)3 bilayer composite on the magnetic bias fields and the frequencies has been studied. The strain with butterfly loop of Tb2(MoO4)3 under an external magnetic field was observed and the effect of ferroelasticity of the Tb2(MoO4)3 on the magnetoelectric coupling was discussed. More than one peak of αE as function of frequency of ac magnetic field were observed and it implies existence of bending resonance mode besides the longitudinal resonance mode in the bilayer composite.
Comparison of structural, microstructural, and electrical analyses of barium strontium titanate thin films
Authors: Suherman P. M. , Tse Y. Y. , Jackson T. J. , Bouyanfif H. , El Marssi M. , Hriljac J. A. , Jones I. P. , Lancaster M. J.
Published: March 2009

The results of structural and electrical characterizations of a barium strontium titanate (Ba0.5Sr0.5TiO3) film, including low temperature x-ray diffraction, low temperature, field dependent Raman spectroscopy, transmission electron microscopy, and low temperature, field dependent microwave measurements, are compared and contrasted. The structural characterization showed the film to be a good single crystal, epitaxial with the (001) MgO substrate. In the ferroelectric state, the tetragonal axis lies in plane leading to a 90° domain structure. A high density of misfit and threading dislocations was observed in the film. The transition to the paraelectric state on warming was shown to be diffuse and appeared to be strongly influenced by local variations in strain which were attributed to the defective microstructure. The dielectric response was also dominated by such effects.
Comparison of PbZr1−xTixO3 thin films deposited on different substrates by liquid delivery metal organic chemical vapor deposition
Authors: Xie Dan , Ruan Yong , Li Rui , Zhang Mingming , Ren Tianling , Liu Litian
Published: March 2009

In the paper, PbZr1−xTixO3 (PZT) thin films were prepared on different substrates including 8 and 4 in. silicon, Pt, Ir, and IrO2/Ir substrates by liquid delivery metal organic chemical vapor deposition. Through optimizing the preparation condition, the better film uniformity of thickness, composition, and temperature was achieved. The thickness uniformity of PZT films on 8 in. substrate was about ±3.24%. The deposition rate of Pb (15.8 nm/min) and Ti (17.9 nm/min) were much faster than that of Zr (2.5 nm/min). The growth temperature of PZT film was 570–630 °C depending on the substrate used. The growth rate of PZT films deposited on Si (30–35 nm/min) was faster than that on metal substrate. The substrate has a great effect on the ferroelectric properties of PZT films. PZT film growing on Ir was much uniform and denser than that on Pt, highlighting the good microstructure achieved. PZT films based on Ir substrate showed excellent ferroelectric properties. At the applied voltage of 5 V, the remanent polarization (2Pr) and coercive field (Ec) values of Ir/IrO2/PZT/IrO2/Ir capacitors were about 36 μC/cm2 and 50 kV/cm, respectively.
Structural study of a sol-gel derived pyrochlore Bi2Ti2O7 using a Rietveld analysis method based on neutron scattering studies
Authors: Kim Sang Su , Park Moon Heum , Chung Jun Ki , Kim Won-Jeong
Published: March 2009

The crystal structure of the sol-gel derived pyrochlore Bi2Ti2O7 has been refined by a Rietveld analysis method using both neutron scattering and x-ray diffraction data. The sample contains a majority Bi2Ti2O7 phase and minor Bi4Ti3O12, Bi12TiO20, and TiO2 phases. A total goodness of fit from neutron and x-ray scatterings were χ2=2.6, Rp=6.5%, and Rwp=8.6%, which suggest that the refinement is reasonable. The structure of the sol-gel derived pyrochlore Bi2Ti2O7 has been identified as a cubic Fd3¯m with a lattice constant of 10.3735(3) Å and the calculated chemical composition of Bi1.896Ti2O6.884. Furthermore, the measured electrical properties of the sol-gel Bi2Ti2O7 thin film exhibit a ferroelectricity evident from the measured electric field dependent polarization. The observed ferroelectricity of the Bi2Ti2O7 thin film is attributed mainly by Bi atoms occupying 96g site in the unit cell with probability of 0.158 based on the refinement result.
Improved electrical properties of Sr0.8Bi2.2Ta2O9 films by ZrSiO4 doping for low voltage operations of metal-ferroelectric-insulator-Si devices
Authors: Lu Xubing , Ishiwara Hiroshi
Published: March 2009

Sr 0.8 Bi 2.2 Ta 2 O 9 (SBT) films were prepared by chemical solution deposition in which ZrSiO4 (ZSO) with concentration ranging from 0 to 10 wt % was incorporated for improving dielectric and leakage current characteristics of the films. X-ray diffraction analysis revealed that no secondary phase and clear degradation of crystallization can be found in ZSO-doped SBT films. Smaller grain size and reduced surface roughness were found for the samples with higher ZSO doping concentration as observed by atomic force microscopy and scanning electron microscopy. The dielectric constant was observed to be much reduced for ZSO-doped SBT films as well as the remnant polarization and coercive field. Films preannealed at 400 °C have a much smaller dielectric constant when compared with that of the films preannealed at 750 °C. Furthermore, a clear reduction in the leakage current and improved fatigue characteristics were observed for ZSO-doped SBT films preannealed at 400 °C. Such improved electrical properties as reduced dielectric constant, leakage current, and coercive field for the ZSO-doped SBT films will be very beneficial for the low voltage operations in metal-ferroelectric-insulator-Si devices.
Ferroelectric and structural properties of stress-constrained and stress-relaxed polycrystalline BiFeO3 thin films
Authors: Nakashima Seiji , Ricinschi Dan , Park Jung Min , Kanashima Takeshi , Fujisawa Hironori , Shimizu Masaru , Okuyama Masanori
Published: March 2009

The stress influence of the structural and ferroelectric properties of polycrystalline BiFeO3 (BFO) thin films has been investigated using a membrane substrate for relaxing stress. Reciprocal space mapping (RSM) measurement has been performed to confirm the stress dependence of the crystal structure of polycrystalline BFO thin films on the Pt (200 nm)/TiO2 (50 nm)/SiO2 (600 nm)/Si (625 μm) substrate (stress-constrained BFO film) and the Pt (200 nm)/TiO2 (50 nm)/SiO2 (600 nm)/Si (15 μm) membrane substrate (stress-relaxed BFO film). The BFO thin films prepared by pulsed laser deposition were polycrystalline and mainly exhibit a texture with (001) and (110) plane orientations. From the RSM results, the crystal structure of the (001)-oriented domain changes from Pm monoclinic to Cm monoclinic or to R3c rhombohedral due to stress relaxation. Moreover, at room temperature as well as at 150 K, remanent polarization (Pr) increases and double coercive field (2Ec) decreases (in the latter case from 88 to 94 μC/cm2 and from 532 to 457 kV/cm, respectively) due to relaxing stress. The enhancement of ferroelectricity is attributed to the crystal structural deformation and/or transition and angle change between the polarization direction and film plane.
Magnetic properties of a Nd–Fe–B sintered magnet with Dy segregation
Authors: Suzuki Hiroyuki , Satsu Yuichi , Komuro Matahiro
Published: March 2009

The magnetic properties and microstructures of a Nd–Fe–B sintered magnet with Dy segregation obtained by applying a fluoride-solution technique were studied using transmission electron microscopy and micromagnetic analysis. By applying 0.1–0.2 wt % fluorides in comparison with weight of the magnet and heating the magnet, coercivity increased by about 1.3 times from 1.1 to 1.4 T at 298 K while retaining remanence. Dy segregated within about 250 nm from the grain surfaces and coercivity was controlled by the area near the grain boundaries. Furthermore, we estimated that the range for reducing the magnetic anisotropy field near the grain boundaries was one or two unit cells by applying micromagnetic analysis to the magnet, which may indicate larger coercivity with less Dy.
Growth and high frequency characterization of Mn doped sol-gel PbxSr1−xTiO3 for frequency agile applications
Authors: Fragkiadakis C. , Lüker A. , Wright R. V. , Floyd L. , Kirby P. B.
Published: March 2009

In pursuit of thin film ferroelectric materials for frequency agile applications that are both easily adapted to large area deposition and also high performance, an investigation has been carried out into sol-gel deposition of 3% Mn doped (Pb0.4Sr0.6)TiO3. Large area capability has been demonstrated by growth of films with good crystallinity and grain structure on 4 in. Si wafers. Metal-insulator-metal capacitors have also been fabricated and development of an improved de-embedding technique that takes parasitic impedances fully into account has enabled accurate extraction of the high frequency dielectric properties of the PbxSr1−xTiO3 films. Practically useful values of ε∼1000, tan δ∼0.03, and tunability ∼50% have been obtained in the low gigahertz range (1–5 GHz). Peaks in the dielectric loss due to acoustic resonance have been modeled and tentatively identified as due to an electrostrictive effect with an electromechanical coupling coefficient of ∼0.04 at an electric field of 240 kV/cm which is potentially useful for tunable thin film bulk acoustic wave devices.
Stranski–Krastanow growth of (112¯2)-oriented GaN/AlN quantum dots
Authors: Lahourcade L. , Valdueza-Felip S. , Kehagias T. , Dimitrakopulos G. P. , Komninou P. , Monroy E.
Published: March 2009

Semipolar GaN(112¯2) deposited on AlN(112¯2) by plasma-assisted molecular-beam epitaxy can follow the Frank–Van der Merwe or the Stranski–Krastanow growth mode as a function of the Ga/N ratio. N-rich grown GaN relaxes elastically at a critical thickness but the resulting GaN islands present multiple crystallographic orientations. In contrast, after deposition of a few two-dimensional GaN monolayers under Ga-rich conditions, a growth interruption in vacuum induces (112¯2)-oriented islanding. Applying this latter procedure, we have synthesized GaN/AlN quantum dot superlattices with reduced internal electric field.
High-gravity-assisted pulsed laser ablation system for the fabrication of functionally graded material thin film
Authors: Nishiyama T. , Morinaga S. , Nagayama K.
Published: March 2009

This paper describes a novel method for the fabrication of a thin film deposited on an appropriate substrate having a continuous composition gradient. The composition gradient was achieved by a combination of pulsed laser ablation (PLA) of the target material with a very strong acceleration field generated on a moving disk rotating at a very high speed. The PLA process was used to produce a cloud of high-energy particles of the target material that will be deposited on a substrate placed on the rotating disk. After deposition, the particles will diffuse on the surface of the thin film under a strong acceleration field. The high energy of the particles and their diffusion on the substrate surface in a high-vacuum environment produces a macroscopic composition distribution in the thin film. We have constructed an experimental apparatus consisting of a vacuum chamber in which a circular disk made of titanium is driven by a high-frequency inductive motor. An acceleration field of up to 10 000 G can be generated by this apparatus. Functionally graded material thin films of FeSi2 with a continuous concentration gradient were successfully fabricated by this method under a gravity field of 5400 G. A significant advantage of this method is that it allows us to fabricate graded thin films with a very smooth surface covered by few droplets.