bluuebunny/crossref_metadata_2025 huggingface dataset:
Incidences of micro-deletion/duplication 22q11.2 detected by multiplex ligation-dependent probe amplification in patients with congenital cardiac disease who are scheduled for cardiac surgery
Authors: Hu Yali , Zhu Xiangyu , Yang Yuehua , Mo Xuming , Sheng Min , Yao Jincui , Wang Dongjing
Published: February 2009

Background

22q11.2 microdeletion is the most common microdeletion in the global population. Congenital cardiac disease is the most frequently observed feature of this syndrome. The prognosis of patients with 22q11.2 copy number aberrations varies from those without 22q11.2 deletion or duplication.

Methods

We enrolled 241 patients from Nanjing Drum Tower Hospital and Nanjing Sick Children’s Hospital, 227 being scheduled for cardiac surgery, and 14 cases being fetuses aged from 24 to 36 gestational weeks. We performed karyotypic analysis and multiplex ligation-dependent probe amplification in all cases.

Results

Karyotypic analysis demonstrated 3 cases with trisomy 21, and 1 case with mosaic trisomy 8 [47,XY,+8/46,XY(1:2)]. Multiplex ligation-dependent probe amplification analysis revealed 10 cases (4.15%) with changes in the number of copies within the region of 22q11.2, of which 7 cases were hemizygous interstitial microdeletion from CLTCL1 to LZTR1, 1 case with deletion of the region from CLTCL1 to PCQAP, and 2 cases with 22q11.2 duplication, one of which spanned from ZNF74 to LZTR1, and simultaneously showed trisomy 21 by karyotyping analysis, and the other spanned from HIC2 to TOP3B. The phenotypes of the cardiac lesions included 3 cases of ventricular septal defect, 3 of tetralogy of Fallot, 2 of combined ventricular and atrial septal defects, and 2 with pulmonary arterial stenosis.

Conclusions

Patients with congenitally malformed hearts who are scheduled for cardiac surgery, as well as fetuses with congenital cardiac disease, should routinely undergo karyotypic analysis and examination for 22q11.2 aberrations. Multiplex ligation-dependent probe amplification has been proven to be a cost-effective diagnostic technique for 22q11 deletion syndrome.
Circulating nerve growth factor in primary and secondary Raynaud’s syndrome – Results of a pilot study
Authors: Klein-Weigel  , Gutsche-Petrak  , Humpel  , Riemekasten  , Ivanov  , Heidrich
Published: February 2009

Background: In this pilot study we examined circulating concentrations of nerve growth factor (NGF) in controls and patients suffering from primary or secondary Raynaud’s syndrome and determined their relation to digital vasospasm. Patients and methods: Eighteen controls, 16 patients with primary RP and 19 patients with systemic sclerosis (SScl) were included. Degree of vasospasm was graduated according to the degree of plethysmographically measured vasospastic reaction after cold test. A diary was handed out for documentation of the daily number and duration of RP during a period of 16 days. Circulating NGF levels were analysed by a commercial ELISA (Promega Inc., USA). Results: SScl-patients were significantly older (p < 0.0001) and more severely affected by spontaneously occurring RP (p = 0.03), whereas the severity of the vasospastic reactions after a standard cold test were not significantly different between the groups (p = 0.09). Within each study group and between the study groups elevated NGF levels were observed only in SScl-patients after thermal provocations (p = < 0.05). In a correlation analysis restricted to patients with PRP or SRP, the degree of vasospasm after cold testing as well as the intensity of Raynaud’s symptoms were not correlated with NGF-levels (p = n.s.). Conclusions: Our results do not support the hypothesis that NGF plays a major role in the generation of vasospasm in Raynaud’s phenomenon.
Lumbar artery aneurysm
Authors: Flügel  , Henschke  , Peck  , Neumann  , Zeller
Published: February 2009

The purpose of this report is to present a rare case of lumbar artery aneurysm. We report the case of a 54-years-old male patient who was misdiagnosed over years having a chronic infrarenal aortic aneurysm. A 64-slice CT at our institution revealed a large lumbar artery aneurysm. The conclusion of this case report is that a lumbar or accessory renal artery aneurysm has to be taken into consideration if there is a localized enlargement of the lower abdominal aorta and a high resolution CT-scan is strongly recommended to make the exact diagnosis.
Percutaneous iliac vein recanalization 17 years after thrombotic occlusion
Authors: Beschorner  , Schwarz  , Rastan  , Sixt  , Noory  , Zeller
Published: February 2009

Persistent venous outflow obstruction of the iliac veins is one of the mechanisms that seem to portend the greatest risk for late development of severe complications. We report the case of a 42-year-old male with postthrombotic occlusion of the left external iliac vein since the age of 25. We managed to recanalize the obstructed vessel and establish a good flow into the inferior vena cava by venous stenting. After successful intervention the patient reported instant symptom relief and was free from venous claudication and leg heaviness at the 6 month follow-up examination. Even after long history of postthrombotic syndrome, venous stenting can be an option for patients with chronic outflow obstructions of the iliac veins.
Intracranial dissection during carotid endarterectomy treated by carotid stenting
Authors: Attigah  , Ganten  , Hyhlik-Dürr  , Kotelis  , Geisbüsch  , Schumacher  , Böckler
Published: February 2009

Intracranial dissection of the internal carotid artery after carotid endarterectomy (CEA) is a serious complication with a potentially fatal outcome. We report on a 67 male with a symptomatic high grad stenosis of the internal carotid artery. Intraoperative completion angiography showed a thrombotic occlusion and the internal carotid artery (ICA) was resected with interposition of a Dacron graft. Completion angiography then revealed a dissection of the petreous ICA, which was corrected by insertion of a coronary artery stent.Stenting of the ICA is a useful tool to restore cerebral perfusion without time delay and completion imaging is extremely helpful for early detection of dissection during CEA.
Die Erfassung des Pubertätsstatus anhand der Pubertal Development Scale
Authors: Watzlawik Meike
Published: February 2009

Zusammenfassung. Die körperliche Entwicklung im Jugendalter hat auch für psychologische Fragestellungen eine große Bedeutung. Es liegen mehrere Verfahren vor, um den Pubertätsstatus ohne Rückgriff auf medizinische Verfahren, die oft teuer und Psychologen nicht direkt zugänglich sind, zu erfassen. Die amerikanische Pubertal Development Scale (PDS, Petersen, Crockett, Richards & Boxer, 1988 ) ist eines dieser Verfahren. Sie ermöglicht, fünf Entwicklungsstadien bei Jungen und Mädchen anhand von jeweils drei Kriterien zu differenzieren. Die vorliegende Studie überprüft verschiedene Gütekriterien einer deutschen Übersetzung. 106 Jungen und 108 Mädchen, im Durchschnitt 11,23 Jahre alt (SD = 0.89), wurden im häuslichen Kontext zu ihrer körperlichen Entwicklung befragt. Eine Fremdeinschätzung des Pubertätsstatus erfolgte durch die Eltern. Die Ergebnisse zeigen zum einen, dass sowohl die interne Konsistenz als auch verschiedene Maße der Kriteriumsvalidität zufriedenstellende Werte erreichen. Zum anderen zeichnen sich jedoch auch systematische Geschlechterunterschiede und Unterschiede in der Fremd- und Selbstbeurteilung ab, die bei der Anwendung und Interpretation der PDS zur Vermeidung von Fehleinschätzungen beachtet werden sollten. Weitere notwendige Validierungsschritte werden diskutiert.
Evaluating deep updraft formulation in NCAR CAM3 with high‐resolution WRF simulations during ARM TWP‐ICE
Authors: Wang Weiguo , Liu Xiaohong
Published: February 2009

The updraft formulation used in NCAR CAM3 deep convection parameterization assumes that the mass flux for a single updraft increases exponentially with height to its top and detrainment is confined only to a thin layer at the updraft top. These assumptions are evaluated against three‐dimensional high‐resolution simulations from the Weather Research and Forecast (WRF) model during the monsoon period of the DOE Atmospheric Radiation Measurement (ARM) Program Tropical Warm Pool–International Cloud Experiment (TWP‐ICE). Analyses of the WRF‐generated updrafts suggest that the mass flux for a single updraft increases with height below the top of the conditionally unstable layer and decreases above. Detrainment may dominate above the conditionally unstable layer rather than only over a thin layer at the updraft top. It is argued that the assumed updraft mass flux profile in CAM3 might be unrealistic in many cases because the updraft acceleration is affected by other drag processes in addition to entrainment. Our analyses suggest that the CAM3‐parameterized convection could be too active and, as a result, excess moisture and heat could be transported to the upper troposphere by the parameterized convection. Future improvement is envisioned.
ShakeOut‐D: Ground motion estimates using an ensemble of large earthquakes on the southern San Andreas fault with spontaneous rupture propagation
Authors: Olsen K. B. , Day S. M. , Dalguer L. A. , Mayhew J. , Cui Y. , Zhu J. , Cruz‐Atienza V. M. , Roten D. , Maechling P. , Jordan T. H. , Okaya D. , Chourasia A.
Published: February 2009

We simulate ground motion in southern California from an ensemble of 7 spontaneous rupture models of large (Mw7.8) northwest‐propagating earthquakes on the southern San Andreas fault (ShakeOut‐D). Compared to long‐period spectral accelerations from the Next Generation Attenuation (NGA) empirical relations, ShakeOut‐D predicts similar average rock‐site values (i.e., within roughly their epistemic uncertainty), but significantly larger values in Los Angeles and Ventura basins due to wave‐guide focusing effects. The ShakeOut‐D ground motion predictions differ from those of a kinematically parameterized, geometrically similar, scenario rupture: (1) the kinematic rock‐site predictions depart significantly from the common distance‐attenuation trend of the NGA and ShakeOut‐D results and (2) ShakeOut‐D predictions of long‐period spectral acceleration within the basins of the greater Los Angeles area are lower by factors of 2–3 than the corresponding kinematic predictions. We attribute these differences to a less coherent wavefield excited by the complex rupture paths of the ShakeOut‐D sources.
Solar wind erosion of the polar regions of the Mars ionosphere
Authors: Pérez‐de‐Tejada H. , Lundin R. , Durand‐Manterola H. , Reyes‐Ruiz M.
Published: February 2009

Measurements conducted with the Analyzer of Space Plasmas and Energetic Atoms (ASPERA‐3) instrument of the Mars Express spacecraft provide data of plasma fluxes that stream away from the polar regions of the Mars ionosphere with energy spectra whose peak value increases with distance from the planetary surface. The observed energy distribution reveals a velocity boundary layer with ionospheric plasma that is eroded from the polar regions of the Mars ionosphere and that extends in the downstream direction within a geometry similar to that present along the polar flanks of the Venus ionosheath. The direction of motion of the ionospheric particles in those fluxes is close to that of the solar wind velocity and is not also oriented in a transverse direction as would have been expected if they were solely accelerated by the convective electric field of the solar wind. The ionospheric plasma eroded and deviated by the solar wind within the boundary layer forms a region whose shape is compatible with that of the asymmetric Mars plasma halo that was inferred from the X‐ray emission lines measured with the reflecting grating spectrometer of the XMM‐Newton telescope. The latter emission is interpreted as resulting from thermal dissipative processes associated with the transport of solar wind momentum to the polar upper ionosphere where both plasma populations interact with each other. Different conditions are applicable throughout most of the dayside hemisphere where the enhanced interplanetary magnetic field intensities that are observed within the ionosphere should make the interaction of the oncoming solar wind plasma with the ionospheric material less efficient.
Energetic particle pressure in Saturn's magnetosphere measured with the Magnetospheric Imaging Instrument on Cassini
Authors: Sergis N. , Krimigis S. M. , Mitchell D. G. , Hamilton D. C. , Krupp N. , Mauk B. H. , Roelof E. C. , Dougherty M. K.
Published: February 2009

The Magnetospheric Imaging Instrument on board Cassini has been providing measurements of energetic ion intensities, energy spectra, and ion composition, combining the Charge Energy Mass Spectrometer over the range 3 to 236 keV/e, the Low Energy Magnetospheric Measurements System for ions in the range 0.024 to 18 MeV, and the Ion and Neutral Camera for ions and energetic neutral atoms in the range 3 to > 200 keV. Results of the energetic (E > 3 keV) particle pressure distribution throughout the Saturnian magnetosphere and comparison with in situ measurements of the magnetic pressure are presented. The study offers a comprehensive depiction of the average, steady state hot plasma environment of Saturn over the 3 years since orbit insertion on 1 July 2004, with emphasis on ring current characteristics. The results may be summarized as follows: (1) The Saturnian magnetosphere possesses a dynamic, high‐beta ring current located approximately between 8 and ∼15 RS, primarily composed of O+ ions, and characterized by suprathermal (E > 3 keV) particle pressure, with typical values of 10−9 dyne/cm2. (2) The planetary plasma sheet shows significant asymmetries, with the dayside region being broadened in latitude (±50°) and extending to the magnetopause, and the nightside appearing well confined, with a thickness of ∼10 RS and a northward tilt of some 10° with respect to the equatorial plane beyond ∼20 RS. (3) The average radial suprathermal pressure gradient appears sufficient to modify the radial force balance and subsequently the azimuthal currents. (4) The magnetic perturbation due to the trapped energetic particle population is ∼7 nT, similar to values from magnetic field–based studies (9 to 13 nT).
Potential of phyllosilicate dehydration and dehydroxylation reactions to trigger earthquakes
Authors: Takahashi Miki , Mizoguchi Kazuo , Masuda Koji
Published: February 2009

This study experimentally simulated dehydration‐ and dehydroxylation‐induced weakening of clay‐rich gouges to investigate the potential of phyllosilicate minerals to generate abnormal pore pressure, triggering earthquakes. For the experiment, the gouge samples were subjected to sliding with heating at 9.6°C/min to 500°C under 80 MPa of confining pressure. In the undrained condition in which expulsed water was confined in the gouges, significant frictional strength reductions were found in the Na‐montmorillonite gouge due to dehydration and in the kaolinite gouge due to dehydroxylation. However, frictional strength continued to increase in the fully drained condition that allowed released water to move outside the gouge. Frictional strengths under the two drained conditions were compared during dehydration and dehydroxylation reactions to estimate the pore pressure generated in the gouge zone under the undrained condition. The 6∼8 wt % of dehydroxylated water generated from the kaolinite caused a rapid increase in pore pressure to 68 MPa at 500°C. In contrast, in the Na‐montmorillonite gouge, the pore pressure gradually increased to 72 MPa as the temperature rose to 500°C. Especially on a coseismic stage, these results suggest that dehydration/dehydroxylation could advance the frictional sliding acceleration induced by frictional heating, even if the fault is in a dry condition.
Satellite‐based midlatitude cyclone statistics over the Southern Ocean: 2. Tracks and surface fluxes
Authors: Yuan Xiaojun , Patoux Jérôme , Li Cuihua
Published: February 2009

Midlatitude cyclone tracks over the Southern Ocean are constructed for the 1999–2006 period using two surface data sets: European Centre for Medium‐range Weather Forecasts (ECMWF) sea‐level pressure analyses on one hand, and on the other hand modified analyses in which high‐wavenumber pressure variability derived from scatterometer swaths has been injected with a wavelet‐based method. A comparison of track statistics reveals the differences between the two data sets. The fluxes of momentum and sensible and latent heat associated with these midlatitude cyclones are calculated and sorted by life span. Three aspects of these cyclone flux statistics are investigated. (1) The momentum flux into the ocean is stronger inside cyclones than over the rest of the Southern Ocean, while the ocean loses more sensible and latent heat outside of the cyclones. (2) The momentum flux into the ocean and the loss of sensible and latent heat by the ocean are larger when calculated from the scatterometer‐modified analyses than when calculated from the original ECMWF analyses. (3) Mesoscale cyclones (short‐lived cyclones) contribute a significant amount of the fluxes between the atmosphere and the Southern Ocean, although over slightly different geographic areas from longer‐lived cyclones.
Soil drainage and vegetation controls of nitrogen transformation rates in forest soils, southern Quebec
Authors: Ullah Sami , Moore Tim R.
Published: February 2009

We investigated the influence of soil drainage class and tree species on nitrogen (N) mineralization and nitrification rates in two forest catenas in southern Quebec. Monthly net N mineralization and nitrification rates were determined along transects running from well‐drained to poorly drained soils for 2 years through in situ incubation of homogenized soils. Potential N transformation rates in soils under American beech, sugar maple, and eastern hemlock trees were determined through incubation of homogenized soils in the laboratory under two different moisture regimes (50 and 100% water by volume) mimicking well‐drained and poorly drained soil conditions in the two watersheds. Field‐based N mineralization rates averaged 38 ± 6 mg m−2 d−1 in well‐drained soils, while those in the poorly drained soils averaged 17 ± 5 mg N m−2 d−1. Similarly, net nitrification rates in well‐drained soils (18 ± 4 mg N m−2 d−1) were 3 times greater than those in poorly drained soils (6 ± 3 mg N m−2 d−1). Laboratory‐based potential N mineralization rates in soils ranked sugar maple > American beech > eastern hemlock under both well‐drained (incubated at 50% water by volume) and poorly drained soil conditions (incubated at 100% water by volume). Potential nitrification rates ranked sugar maple > American beech > eastern hemlock under well‐drained soil conditions, while under poorly drained conditions, American beech > sugar maple ≥ eastern hemlock. Nitrification enzyme activity determined through a soil slurry method correlated significantly with field‐based nitrification rates. Differences in soil volumetric water contents, leaf litter N input, and soil C:N ratios, as surrogates of soil drainage and floristic heterogeneity, respectively, correlated significantly with field‐based N mineralization and nitrification rates. Field‐based N mineralization and nitrification rates were higher in summer than in early spring and autumn. Soil drainage class and tree species exert marked controls over N transformation rates in forested landscapes and need to be incorporated when characterizing and/or modeling internal N cycling at watershed scales.
Use of spatially distributed stream stage recorders to augment rain gages by identifying locations of thunderstorm precipitation and distinguishing rain from snow
Authors: Lundquist Jessica , Huggett Brian , Roop Heidi , Low Natalie
Published: February 2009

Precipitation measurements in complex terrain are difficult to obtain, particularly during convective thunderstorm precipitation or mixed rain and snow. In such cases, stream stage recorders distributed across many small, headwater streams can bridge the gap between point measurements of precipitation and larger‐scale total basin discharge. We use case studies from two steep basins with shallow soils in the Sierra Nevada, California to illustrate how distributed stream sensors can help identify the location, timing, and intensity of spatially variable precipitation.
Photoelectric properties of Bi2O3∕GaSe heterojunctions
Authors: Leontie L. , Evtodiev I. , Nedeff V. , Stamate M. , Caraman M.
Published: February 2009

Photoelectrical characteristics and photoluminescence of n-Bi2O3∕p-GaSe structures have been investigated. They show photosensitivity in the photon energy range of 1.85–3.10eV. During thermal treatment of the heterojunction, Bi and O atoms diffuse into the GaSe layer, forming two impurity levels located at 0.101 and 0.429 eV above the valence-band top of GaSe.
Site determination of Zn doping in protein encapsulated ZnxFe3−xO4 nanoparticles
Authors: Pool V. L. , Klem M. T. , Holroyd J. , Harris T. , Arenholz E. , Young M. , Douglas T. , Idzerda Y. U.
Published: February 2009

The x-ray absorption spectra of the Fe and Zn L edges for 6.7nm Fe3O4 nanoparticles grown inside 12nm ferritin protein cages with 10%, 15%, 20%, and 33% zinc doping show that Zn is substitutional as Zn2+ within the iron oxide host structure. A Neel–Arrhenius plot of the blocking temperature in frequency dependent ac-susceptibility measurements shows that the particles are noninteracting and that the anisotropy energy barrier is reduced with Zn loading. X-ray magnetic circular dichroism of the Fe displays a linear decrease with Zn doping in sharp contrast to the initial increase present in the bulk system. The most plausible explanation for the decrease in moment is that Zn substitutes preferentially into the tetrahedral A site as a Zn2+ cation, generating a mixed spinel.
Remanent states and magnetization reversal of nanopatterned spin-valve elements using off-axis electron holography
Authors: He Kai , Smith David J. , McCartney Martha R.
Published: February 2009

Remanent states and reversal behavior of nanopatterned spin-valve elements have been investigated using off-axis electron holography and Lorentz microscopy. Arrays of 30-nm-thick Co∕Cu∕Py (12, 6, and 12nm, respectively) slotted rings with typical outer diameters ranging from 300to600nm and slot angles of 30°, 60°, and 90° were fabricated by electron-beam lithography. Flux-closure configurations, with zero or one vortex, were the most common remanent states when magnetic fields were applied perpendicular to the slot direction. More complex configurations were introduced for fields parallel to the slot direction. Slotted nanorings with 300∕100nm of outer or inner diameter had the most uniform remanent configuration of fully closed flux. Holographic phase images confirmed that the Co and Py layers were coupled in opposite directions at remanence to minimize demagnetization energy. Magnetization reversal processes were investigated: the in-plane switching fields needed to fully reverse both ferromagnetic layers were typically on the order of 600Oe.
Ultrahigh-Hc granular media with [CoB∕Pt]n multilayer film sputtered under Ar+O2 atmosphere
Authors: Nemoto Hiroaki , Takekuma Ikuko , Araki Ryoko , Tanahashi Kiwamu , Nakatani Ryoichi
Published: February 2009

We developed a [Co∕Pt]n multilayer film for fabricating a perpendicular recording film with an ultrahigh coercivity (Hc). Adding boron into each Co layer and further introducing O2 during deposition yielded a high Hc of 1200kA∕m. Transmission electron microscopy and magnetic measurements suggested that the intergranular exchange coupling was reduced to the level of conventional CoCrPt-oxide granular films. The [CoB∕Pt]n+O multilayer film is applicable to a hard magnetic layer in exchange-coupled composite media as well as energy-assisted magnetic recording media.
Growth and characterization of 144 μm thick barium ferrite single crystalline film for microwave device application
Authors: Jalli Jeevan , Hong Yang-Ki , Bae Seok , Lee Jae-Jin , Abo Gavin S. , Lyle Andrew , Gee Sung-Hoon , Lee Hwachol , Mewes Tim , Sur Jeong-Chul , Lee Sung-Ik
Published: February 2009

Liquid phase epitaxy technique was used to grow 144 μm thick barium ferrite (BaFe12O19; BaM) single crystalline films on (111) Gd3Ga5O12 substrate. The growth rate of 72 μm/h was achieved with a flux system of Fe2O3–BaCO3–Na2CO3. The grown BaM films show single crystalline (000l) orientation that was confirmed by x-ray diffraction and magnetic torque curves. The saturation magnetization (4πMs) and the anisotropy field (Hk) were found to be 4.2 kG and 16.0 kOe, respectively. The ferrimagnetic resonance linewidth (ΔH) at 35 GHz was measured to be 0.1 kOe.
Ferromagnetism in UCoGe stabilized by transition metal doping
Authors: Pospíšil J. , Vejpravová J. Poltierová , Diviš M. , Sechovský V.
Published: February 2009

Polycrystalline samples of UCoGe doped by 1% and 5% of Fe, Ni, and Ru, respectively, have been prepared. Magnetization, ac susceptibility, and electrical resistivity measurements were done on samples in as cast state and annealed at 900 °C for 10 days. The TiNiSi-type orthorhombic crystal structure proved by x-ray powder diffraction was confirmed in the whole series of compounds. Except for the 1% Ni doped sample, all the other samples exhibit clear spontaneous ferromagnetism. The 5% doped compounds have the Curie temperature of TC=6.5 K for U(Co,Fe)Ge, TC=5.0 K for U(Co,Ni)Ge, and TC=7.5 K for U(Co,Ru)Ge. All the studied compounds exhibit only small spontaneous magnetic moments around 0.04μB at 1.8 K. The increasing TC value and stabilization of magnetic moments induced by the transition metals doping are accompanied by a shift in the superconducting transition to lower temperatures with respect to pure UCoGe (TSC≈0.7 K). The 5% doped samples show no sign of superconductivity down to T=0.4 K.
Localized measurement of short wavelength plasma fluctuations with the DIII-D phase contrast imaging diagnostic
Authors: Dorris J. R. , Rost J. C. , Porkolab M.
Published: February 2009

A novel rotating mask system has been designed and implemented on the DIII-D phase contrast imaging (PCI) diagnostic to produce the first spatially localized PCI measurements of a tokamak plasma. The localization technique makes use of the variation in the magnetic field component perpendicular to the viewing chord as a function of chord height. This new capability provides measurements in the range of 2<k<30 cm−1, 10 kHz<f<10 MHz, and 0.7<r/a<1. This technique provides a spatial resolution of 10 cm at k=15 cm−1 and can realistically provide measurements at a rate of 10 profiles/s. Calibration measurements show accurate characterization of the system transfer function making feasible a time dependent analysis that results in improved localization. Initial measurements show turbulence to peak near the plasma edge. This upgrade is part of a broader program to operate the DIII-D PCI at wave numbers up to 40 cm−1 to probe electron scale turbulence in the plasma core.
Effect of hybridization on the magnetic properties of correlated two-band metals
Authors: Chaves C. M. , Troper A.
Published: February 2009

The magnetic properties of transitionlike metals are discussed within the single-site approximation, which is a picture to take into account electron correlations. The metal is described by two hybridized bands one of which includes Coulomb correlation. The presented results indicate that ferromagnetism arises for adequate values of hybridization (V), correlation (U), and occupation number (nσ). Some similarities with dynamical mean-field theory are indicated.
Nonstoichiometry, point defects, and magnetoresistance of Sr2FeMoO6−δ
Authors: Töpfer J. , Kircheisen R. , Barth S.
Published: February 2009

The phase stability, nonstoichiometry, point defects, and magnetoresistance (MR) of polycrystalline Sr2FeMoO6−δ (SFMO) were studied. Thermogravimety at 1200 °C in combination with x-ray diffraction shows that single-phase SFMO exists between −10.2≤log pO2≤−13.7 at 1200 °C. At lower oxygen partial pressure mass loss signals reductive decomposition; at higher pO2 a mass gain indicates oxidative decomposition into SrMoO4 and SrFeO3−x. The nonstoichiometry δ at 1200 °C was measured as function of pO2 and oxygen vacancies were found to represent majority defects. The vacancy concentration increases with decreasing pO2; a maximum nonstoichiometry of δ=0.086 is observed close to the lower phase boundary. Samples with different δ were prepared at 1200 °C and various pO2. The variation of structural parameters, magnetization, and MR is discussed in relation to oxygen nonstoichiometry δ. Maximum MR=6.5% at 298 K and 1 T is observed for samples with large δ.
Quantitative comparison of double-stator and traditional permanent magnet brushless machines
Authors: Niu Shuangxia , Chau K. T. , Yu Chuang
Published: February 2009

In this paper, both the steady-state and dynamic performances of the double-stator permanent magnet brushless (DS-PMB) machines, including the surface-mounted topology (DS-SPMB) and the interior topology (DS-IPMB), are quantitatively compared with that of the traditional single-stator SPMB (SS-SPMB) machine. Based on the same electric loading and magnetic loading, the DS-SPMB and DS-IPMB machines are designed to have the same output power, while the DS-SPMB and SS-SPMB machines are of the same peripheral dimensions. The steady-state and transient characteristics of these machines are simulated by using the circuit-field-torque time-stepping finite element method. Finally, the preferred machine, namely, the DS-SPMB one, is prototyped and tested for experimental verification.
Ultrahigh-density (001)-oriented FePt nanoparticles by atomic-scale-multilayer deposition
Authors: Wang Liang-Wei , Wu Yun-Chung , Lai Chih-Huang
Published: February 2009

Highly ordered (001)-oriented FePt nanoparticles (NPs) with controllable sizes and well-aligned easy axis were obtained by tuning the total layer number n of atomic-scale [Fe/Pt/SiO2]n multilayers deposited on SiO2∥Si substrates. After annealing at 700 °C, the ordered FePt NPs with a small particle size of 5.5 nm (an extremely high areal density of 1.2×1013dots/in.2), a large out-of-plane coercivity of 28.5 kOe, and a narrow size distribution of 13% were attained. All NPs were embedded in the SiO2 substrates, resulting in a flat top surface. Finally, a full-stack film structure of perpendicular recording media composed of FePt NPs (recording layer), SiO2 (nonmagnetic intermediate layer) and CoZrTa (soft underlayer) was demonstrated.
Microstructure and magnetic properties of FeCo epitaxial thin films grown on MgO single-crystal substrates
Authors: Shikada Kouhei , Ohtake Mitsuru , Kirino Fumiyoshi , Futamoto Masaaki
Published: February 2009

FeCo epitaxial films were prepared on MgO(100), MgO(110), and MgO(111) substrates by ultrahigh vacuum molecular beam epitaxy. FeCo thin films with (100), (211), and (110) planes parallel to the substrate surface grow on respective MgO substrates. FeCo/MgO interface structures are studied by high-resolution cross-sectional transmission electron microscopy and the epitaxial growth mechanism is discussed. Atomically sharp boundaries are recognized between the FeCo thin films and the MgO substrates where misfit dislocations are introduced in the FeCo thin films presumably to decrease the lattice misfits. Misfit dislocations are observed approximately every 9 and 1.4 nm in FeCo thin film at the FeCo/MgO(100) and the FeCo/MgO(110) interfaces, respectively. X-ray diffraction analysis indicates that the lattice spacing measured parallel to the single-crystal substrate surfaces are in agreement within 0.1% with those of the respective bulk values of Fe50Co50 alloy crystal, showing that the FeCo film strain is very small. The magnetic anisotropies of these epitaxial films basically reflect the magnetocrystalline anisotropy of bulk FeCo alloy crystal.
Analytical and experimental analysis of noise passage through hysteretic systems
Authors: Dimian Mihai , Coca Eugen , Popa Valentin
Published: February 2009

Relation between noise and hysteresis has been recently under intensive research focus due to the fundamental challenges posed by noise and fluctuations in ultrasmall semiconductor and magnetic devices. However, a systematic analysis of hysteretic materials and devices driven by noisy input has been rather limited. On the one hand, this situation is related to lack of general analytical tools for addressing complex non-Markovian processes found at the output of hysteretic systems. On the other hand, noise is usually an internal characteristic of a physical system with limited control from experimental point of view. Our analytical approach to the analysis of noise passage through hysteretic systems is based on embedding the non-Markovian output processes in multidimensional Markovian processes defined on graph, while the experimental setup involves Hameg 8131-2 noise generators and Schmidt triggers as hysteretic rectangular loop operators. General features of noise passage through elementary hysteretic systems are first examined and their dependence of various parameters is discussed.
Magnetization dependent vector model and single domain nanostructures
Authors: Cardelli E. , Carpentieri M. , Della Torre E. , Drisaldi G. , Faba A.
Published: February 2009

In this paper we present a phenomenological approach computing the behavior of a cobalt particle by the Della Torre–Pinzaglia–Cardelli (DPC) model. The identification of the model is realized using a suitable numerical procedure and a set of data obtained using a micromagnetic numerical model based on Brown’s equations. In order to simplify the identification, a class of hysterons, which describes the magnetization process of a single domain in agreement with the Stoner and Wohlfarth theory, is used. The accuracy of the reconstructed magnetization cycles using the DPC model and the save of the computation time with respect to the micromagnetic numerical model are shown.
Current-driven domain wall in giant magnetoresistance half-ring series wires with varied linewidth
Authors: Cheng K. W. , Yu C. , Lee S. F. , Yao Y. D. , Liou Y. , Huang J. H.
Published: February 2009

Results on both field driven and current induced domain wall motion in Co/Cu/Ni80Fe20 trilayered half-ring in-series wires with different linewidths were presented. The switching behavior depends linearly on the linewidth of Co/Cu/Ni80Fe20 trilayered half-ring structures. A larger bias field (Hb) applied to the samples results in a smaller critical current needed to reverse magnetization. The critical current density was observed to be 3×107 A/cm2 for Ni80Fe20 and 2×108 A/cm2 for Co at zero field. The results of the numbers of giant magnetoresistance jump (digital) versus external magnetic field and current densities (analog) of this design have potential utility as an analog-digital converter.
Electrodynamic model for low loss microwave nanocomposite magnets using autonomous blocks with Floquet channels
Authors: Pardavi-Horvath M. , Makeeva G. S. , Golovanov O. A.
Published: February 2009

The diagonal and off-diagonal components of the effective permeability tensor and the effective permittivity of three-dimensional (3D) periodic magnetic nanosystems, depending on the size and separation of the magnetic nanoparticles, were calculated using the computed values of the propagation constants and the dispersion relations of clockwise and counterclockwise polarized electromagnetic waves (EMWs), as well as for the ordinary and extraordinary modes in the gyromagnetic medium. The propagation constants of EMWs in a 3D periodic array of 150 nm iron nanospheres in a dielectric matrix, depending on the ratio of the period of the array to the radius of the nanospheres, were obtained at a frequency f=30 GHz for longitudinal and transverse orientations of the bias magnetic field. It is shown that the magnetic and dielectric losses of weakly interacting systems are lower than that of yttrium iron garnet (YIG); however, losses increase due to spin wave (SW) excitations upon reduced separation.
Nonequilibrium umbrella sampling in spaces of many order parameters
Authors: Dickson Alex , Warmflash Aryeh , Dinner Aaron R.
Published: February 2009

We recently introduced an umbrella sampling method for obtaining nonequilibrium steady-state probability distributions projected onto an arbitrary number of coordinates that characterize a system (order parameters) [A. Warmflash, P. Bhimalapuram, and A. R. Dinner, J. Chem. Phys. 127, 154112 (2007)]. Here, we show how our algorithm can be combined with the image update procedure from the finite-temperature string method for reversible processes [E. Vanden-Eijnden and M. Venturoli, “Revisiting the finite temperature string method for calculation of reaction tubes and free energies,” J. Chem. Phys. (in press)] to enable restricted sampling of a nonequilibrium steady state in the vicinity of a path in a many-dimensional space of order parameters. For the study of transitions between stable states, the adapted algorithm results in improved scaling with the number of order parameters and the ability to progressively refine the regions of enforced sampling. We demonstrate the algorithm by applying it to a two-dimensional model of driven Brownian motion and a coarse-grained (Ising) model for nucleation under shear. It is found that the choice of order parameters can significantly affect the convergence of the simulation; local magnetization variables other than those used previously for sampling transition paths in Ising systems are needed to ensure that the reactive flux is primarily contained within a tube in the space of order parameters. The relation of this method to other algorithms that sample the statistics of path ensembles is discussed.
Tunnel magnetoresistance effect in double magnetic tunnel junctions using half-metallic Heusler alloy electrodes
Authors: Ohdaira Yusuke , Oogane Mikihiko , Ando Yasuo
Published: February 2009

Double magnetic tunnel junctions (DMTJs) using half-metallic Co2MnSi Heusler alloy electrodes were fabricated. Their tunnel magnetoresistance (TMR) effects were then investigated. Large TMR ratios were observed as 25% at room temperature and as 320% at 6 K. The bias voltage dependence of tunnel conductance suggests a half-metallic nature of the Co2MnSi electrode. These results show that high-quality DMTJ with half-metallic Heusler alloy electrodes was fabricated and that the DMTJ exhibited the expected performance.
Focusing surface plasmon polariton trapping of colloidal particles
Authors: Fang Zheyu , Lin Feng , Huang Shan , Song Wentao , Zhu Xing
Published: February 2009

We report focusing surface plasmon polariton (SPP) trapping of colloidal particles without optical interactions. Using a silver nanostructure, we demonstrate SPP launching and propagation under a p-polarized incident laser. In-plane Fresnel zone plate (FZP) is used to focus the SPP waves. Colloidal particles can be trapped at the silver nanostructure in the illumination region and the FZP focus area by focusing SPP force. The SPP tweezers open new perspectives in the subwavelength trapping and applications to lab-on-chip devices.
Multimode thermoelastic dissipation
Authors: Chandorkar Saurabh A. , Candler Robert N. , Duwel Amy , Melamud Renata , Agarwal Manu , Goodson Kenneth E. , Kenny Thomas W.
Published: February 2009

In this paper, we investigate thermoelastic dissipation (TED) in systems whose thermal response is characterized by multiple time constants. Zener [Phys. Rev. 52, 230 (1937)] analyzed TED in a cantilever with the assumption that heat transfer is one dimensional. He showed that a single thermal mode was dominant and arrived at a formula for quantifying the quality factor of a resonating cantilever. In this paper, we present a formulation of thermoelastic damping based on entropy generation that accounts for heat transfer in three dimensions and still enables analytical closed form solutions for energy loss estimation in a variety of resonating structures. We apply this solution technique for estimation of quality factor in bulk mode, torsional, and flexural resonators. We show that the thermoelastic damping limited quality factor in bulk mode resonators with resonator frequency much larger than the eigenfrequencies of the dominant thermal modes is inversely proportional to the frequency of the resonator unlike in flexural mode resonators where the quality factor is directly proportional to the resonant frequency. Purely torsional resonators are not limited by TED as the deformation is isochoric. We show that it is possible to express the quality factor obtained by full three-dimensional analyses as a weighted sum of Zener formula based modal quality factors. We analytically estimate the quality factor of a cantilever and a fixed-fixed beam and corroborate it with data to show that the assumption of a single dominant thermal mode, which is valid in one-dimensional analysis, is violated. The analytical formulation described in this paper permits estimation of energy lost due to heat transfer in orthogonal directions. It is found that the entropy generated due to heat transfer along the beam becomes significant in beams with aspect ratio (length/width) below 20.
Fast algorithms for classical X→ diffusion-reaction processes
Authors: Thalmann Fabrice , Lee Nam-Kyung
Published: February 2009

The Doi formalism treats a reaction-diffusion process as a quantum many-body problem. We use this second-quantized formulation as a starting point to derive a numerical scheme for simulating X→0 reaction-diffusion processes, following a well-established time discretization procedure. In the case of a reaction zone localized in the configuration space, this formulation provides also a systematic way of designing an optimized, multiple time step algorithm, spending most of the computation time to sample the configurations where the reaction is likely to occur.
Composition at the interface between multicomponent nonequilibrium fluid phases
Authors: Haugen Kjetil B. , Firoozabadi Abbas
Published: February 2009

The computation of mass transfer between two nonequilibrium phases requires interfacial composition. For a system with a total of M components, the assumption of local thermodynamic equilibrium provides only M equations while the number of unknown interfacial compositions is 2(M−1). In binary systems (M=2), the number of equations matches the number of unknowns and the interfacial composition is readily computed at any temperature and pressure. In multicomponent systems (M≥3), the number of unknowns exceeds the number of equations and additional constraints are required. To the best of our knowledge, a general solution to the problem of computing interfacial composition in multicomponent systems has not been presented in the past, despite its fundamental importance. In this work we present a general and consistent method of computing interfacial composition where the additional constraints are obtained from mass balance across the interface. The derivations reveal that in multicomponent systems interfacial composition depends on the diffusion coefficients in the two bulk phases. This is a fundamental difference from binary systems. The differences are demonstrated by comparing examples of mixing of nonequilibrium phases in binary and ternary (M=3) systems.
A functional of the one-body-reduced density matrix derived from the homogeneous electron gas: Performance for finite systems
Authors: Lathiotakis N. N. , Helbig N. , Zacarias A. , Gross E. K. U.
Published: February 2009

An approximation for the exchange-correlation energy of reduced-density-matrix-functional theory was recently derived from a study of the homogeneous electron gas [N. N. Lathiotakis, N. Helbig, and E. K. U. Gross, Phys. Rev. B 75, 195120 (2007)]. In the present work, we show how this approximation can be extended appropriately to finite systems, where the Wigner Seitz radius rs, the parameter characterizing the constant density of the electron gas, needs to be replaced. We apply the functional to a variety of molecules at their equilibrium geometry and also discuss its performance at the dissociation limit. We demonstrate that, although originally derived from the uniform gas, the approximation performs remarkably well for finite systems.
Organic light-emitting diodes using 3,6-difluoro-2,5,7,7,8,8-hexacyanoquinodimethane as p-type dopant
Authors: Mi Bao Xiu , Gao Zhi Qiang , Cheah Kok Wai , Chen Chin H.
Published: February 2009

We demonstrate that 3,6-difluoro-2,5,7,7,8,8-hexacyanoquinodimethane (F2-HCNQ) can serve as an excellent electrical doping material for hole transport materials with the highest occupied molecular orbital level as high as 5.4 eV, such as N,N′-di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB). With its relatively strong electron-accepting ability and high thermal stability, F2-HCNQ doped NPB organic light-emitting diode (OLED) showed improved power efficiency with low driving voltage. The tris(8-hydroxyquinoline)aluminum based OLED with F2-HCNQ doped NPB layer and Cs2O doped bathophenanthroline electron transport layer exhibits power efficiency of 3.6 lm/W with driving voltage of 3.2 V at 100 cd/m2.
Enhancement of room temperature ferromagnetism in C-doped ZnO films by nitrogen codoping
Authors: Yi J. B. , Shen L. , Pan H. , Van L. H. , Thongmee S. , Hu J. F. , Ma Y. W. , Ding J. , Feng Y. P.
Published: February 2009

The effect of nitrogen on the magnetic properties of C-doped ZnO has been investigated. It has been found that a low concentration of N doping does not lead to an apparent change of the magnetization in C-doped ZnO films. When N doping concentration exceeds 0.05 at. %, the magnetization of C–ZnO films increases significantly (more than 85%). The increased magnetization is mainly due to the enhanced moment of carbon, resulted from N doping. The successful fabrication of p-type diluted magnetic semiconductor may be of interest for spintronic applications.
Switchable wiring for high-resolution electronic measurements at very low temperatures
Authors: Schirm C. , Pernau H.-F. , Scheer E.
Published: February 2009

Low-temperature transport measurements with high energy resolution require effective filtering of high-frequency input. The high dc resistance of standard RC filters results in considerable heat input and hampers measurements with high currents or voltages. We developed a wiring scheme that incorporates a commercial latching relay at very low temperature between two sets of wires. In our application one set of wires comprises a voltage divider and a high-Ohmic reference resistance at low temperature as well. The other set has low dc resistance and no voltage divider. Both sets are high frequency filtered with very robust and compact filters, though, for insuring effective damping at gigahertz frequencies. We demonstrate that with the first set, we obtain a voltage resolution of 6 μV and a current resolution of 100 pA, which is sufficient for the recording and analysis of multiparticle transport in superconducting point contacts. The second set is used for electromigration experiments on superconducting point contacts and allows application of currents up to 1 mA and voltages up to 20 V, while the sample is at 1 K. More versatile applications of the scheme are possible.
Comment on “Electronic structure and zone-center phonon modes in multiferroic bulk BiFeO3” [J. Appl. Phys. 103, 083712 (2008)]
Authors: Hermet P. , Goffinet M. , Ghosez Ph.
Published: February 2009

In a recent paper, Tütüncü and Srivastava [J. Appl. Phys. 103, 083712 (2008)] report the electronic structure and the assignment of the zone-center phonon modes of the R3c phase of BiFeO3 using the density functional theory. In the present comment, we point out some physical inaccuracies in their mode assignment. We review their interpretation and analyze which conclusions are actually justified.