bluuebunny/crossref_metadata_2025 huggingface dataset:
Mitochondrial Syndromic Sensorineural Hearing Loss
Authors: Forli F. , Passetti S. , Mancuso M. , Seccia V. , Siciliano G. , Nesti C. , Berrettini S.
Published: May 2007

Mitochondrial diseases (MD) are a clinically heterogeneous group of disorders that arise as a result of dysfunction of the mitochondrial respiratory chain. Sensorineural hearing loss (SNHL) is often associated to mitochondrial dysfunctions both in syndromic, nonsyndromic forms. SNHL has been described in association to different mitochondrial multisystemic syndromes, often characterized by an important neuromuscular involvement. Because of the clinical relevance of the associated neurological symptoms, the occurrence of SNHL is often underestimated and undiagnosed. In this study we evaluated the incidence of SNHL in a group of 17 patients with MD. We detected some degree of hearing impairment in 8/17 patients (47%), thus confirming the frequency of hearing impairment in MD. Furthermore, we want to highlight the role of the audiologist and otolaryngologist in the diagnosis and characterization of a MD, which should be suspected in all the cases in which the hearing loss is associated to signs and symptoms characteristic of mitochondrial dysfunction, especially if the family history is positive for hearing loss or MD in the maternal line.
The influence of territory characteristics and food supply on the breeding performance of the Red‐backed Shrike (Lanius collurio) in an extensively farmed region of eastern Poland
Authors: Goławski Artur , Meissner Włodzimierz
Published: May 2007

The breeding performance of the Red‐backed Shrike (Lanius collurio) in relation to the territory characteristics was investigated. The study was conducted in an area of high agricultural land use, characterised by small field size, a more mosaic habitat and low use of mineral fertilisers in comparison to Western European countries. The influence of habitat structure and composition in the territory on the date of clutch initiation, nest predation and clutch size in the Red‐backed Shrike was not found, but such an influence on the number of nestlings was shown. The minimum adequate model explained 18.3% of the variation between territories in nestling's number. The number of fledglings was positively correlated with the area of pastures, meadows, orchards and fallows within territories, and negatively correlated with length of overhead transmission lines. The number of fledglings was correlated with food abundance within territories, based on to the results from pitfall traps. There was no correlation between territory food abundance and the size of clutch. The presence of pastures, meadows and fallows, which are foraging places, thus seems to be crucial for the protection of the Red‐backed Shrike.
Frying Performance of No‐trans, Low‐Linolenic Acid Soybean Oils
Authors: Gerde Jose , Hardy Connie , Fehr Walter , White Pamela J.
Published: May 2007

Two extruded‐expelled physically refined soybean oils with reduced contents of linolenic acid, ultra‐low‐ linolenic acid (ULL, 1.5%) and low‐linolenic acid (LL, 2.6%), and a extruded‐expelled physically refined control oil (control, 5.3% linolenic acid) were evaluated by frying French fries in a commercial‐like setting for 6 h day−1 during 23 days. The oils became darker, increased in yellow color at the beginning, and became redder and less green throughout the process. Free fatty acids levels were not different among the oils until day 14, after which, ULL was different from the control for the remainder of frying. The conjugated dienoic acid values were greatest in the control. Generally, ULL and LL oils had lower percentages of polar compounds than did the control, providing a frying life 2 days longer than the control and ~30% increase in frying time. A trained sensory panel evaluated the French fries on days 2, 5, and 6. Buttery and potato flavors decreased, and rancid and painty flavors increased over frying time for all products. Rancid flavor was highest in the fries from the control oil. Overall, the ULL and LL oils performed better than did the control oil and ULL tended to perform better than the LL.
Baclofen‐enhanced spinal cord stimulation and intrathecal baclofen alone for neuropathic pain: Long‐term outcome of a pilot study
Authors: Lind Göran , Schechtmann Gastón , Winter Jaleh , Meyerson Björn A. , Linderoth Bengt
Published: May 2007

In a previously published pilot study, we addressed the possibility to increase the effectiveness of spinal cord stimulation (SCS) applied for neuropathic pain by using adjunct pharmacological therapy. This combined treatment approach was a direct spin‐off from animal experiments aiming at the exploration of transmitter and receptor mechanisms involved in the pain relieving effect of SCS. Out of 48 patients with neuropathic pain of peripheral origin responding poorly to SCS, seven received pumps for intrathecal baclofen (GABA‐B receptor agonist) delivery together with SCS, and four had pumps alone. In order to assess the long‐term effect a follow‐up has been performed, with an average, total treatment time of 67 months. At the follow‐up the remaining nine patients still enjoy about the same pain relief as initially, but with a mean, further dose increase of about 30%. This study demonstrates that a deficient SCS effect in neuropathic pain may be considerably improved by intrathecal baclofen administration, and that this enhanced effect persists for a long‐time. On‐going and future animal studies may provide new and even more efficient pharmaceutical candidates for such combined therapy.
Quetiapine versus risperidone in elderly patients with behavioural and psychological symptoms of dementia: Efficacy, safety and cognitive function
Authors: Rainer M. , Haushofer M. , Pfolz H. , Struhal C. , Wick W.
Published: May 2007

Objective

In this study we directly compared the efficacy and tolerability of the atypical antipsychotics quetiapine and risperidone in elderly patients with dementia and symptoms of disturbed perception, thought content, mood or behaviour (behavioural and psychological symptoms of dementia—BPSD).

Methods

We conducted an 8-week, rater-blinded, randomised study of 72 outpatients (55–85 years) with BPSD (assessed by NPI baseline score), who received flexibly-dosed quetiapine (50–400 mg/day) or risperidone (0.5–2 mg/day). Primary efficacy measure: Neuropsychiatric Inventory (NPI) Parts 1 and 2; secondary efficacy measures: Clinical Global Impression (CGI), Cohen-Mansfield Agitation Inventory (CMAI), Mini-Mental State Examination (MMSE), Age-adjusted concentration test (AKT). Safety evaluations included the incidence of extrapyramidal symptoms (EPS) and adverse events (AEs).

Results

Sixty-nine of 72 patients were evaluable for efficacy (72 were evaluated for safety), 4 patients discontinued (3 due to AEs: quetiapine 2, risperidone 1; 1 lost to follow-up). Sixty-five patients received quetiapine (n = 34; mean dose 77 ± 40 mg/day) or risperidone (n = 31; mean dose 0.9 ± 0.3 mg/day). There was no significant difference between treatments on NPI scores; within treatment groups, NPI scores decreased significantly from baseline to Week 8 (P ≤ 0.05 vs. baseline). Most patients (quetiapine arm 67.6%, risperidone arm 71.0%) experienced clinical improvement (CGI-Improvement scores); both agents reduced agitation (CMAI scores); and there was no cognitive impairment (MMSE and AKT scores). There were no significant differences between treatments in any safety measures, including EPS. Four patients experienced serious AEs (quetiapine arm 3; risperidone arm 1); none were considered treatment-related by the study investigator. There were no cerebrovascular AEs or deaths.

Conclusions

Quetiapine or risperidone, at low doses, were equally effective and generally well tolerated (including no cognitive impairment) in the treatment of BPSD in elderly patients.
Glycoprotein folding and the role of EDEM1, EDEM2 and EDEM3 in degradation of folding‐defective glycoproteins
Authors: Olivari Silvia , Molinari Maurizio
Published: May 2007

Proteins synthesized in the endoplasmic reticulum (ER) lumen are exposed to several dedicated chaperones and folding factors that ensure efficient maturation. Nevertheless, protein folding remains error‐prone and mutations in the polypeptide sequence may significantly reduce folding‐efficiency. Folding‐incompetent proteins carrying N‐glycans are extracted from futile folding cycles in the calnexin chaperone system upon intervention of EDEM1, EDEM2 and EDEM3, three ER‐stress‐induced members of the glycosyl hydrolase 47 family. This review describes current knowledge about mechanisms regulating folding and disposal of glycoproteins.
Divergent microsatellite evolution in the human and chimpanzee lineages
Authors: Gáspári Zoltán , Ortutay Csaba , Tóth Gábor
Published: May 2007

Comparison of the complete human genome sequence to one of its closest relatives, the chimpanzee genome, provides a unique opportunity for exploring recent evolutionary events affecting the microsatellites in these species. A simple assumption on microsatellite distribution is that the total length of perfect repeats is constant compared to that of imperfect ones regardless of the repeat sequence. In this paper, we show that this is valid for most of the chimpanzee genome but not for a number of human chromosomes. Our results suggest accelerated evolution of microsatellites in the human genome relative to the chimpanzee lineage.
The Thin Cross Finger Skin Flap
Authors: GOKREM S. , TUNCALI D. , TERZIOGLU A. , TOKSOY K. , ASLAN G.
Published: May 2007

The cross-finger flap has been used successfully for decades. Traditionally, the flap is elevated in the plane lying superficial to the extensor tendon. This damages the delicate subcutaneous tissues, which are important for the lengthening capacity of the skin of the dorsum of the fingers during flexion and extension. In this report, we present a modification of elevation of the cross-finger flap in a plane superficial to the dorsal veins of the fingers. This modification prevents donor finger complications such as poor graft take, extensor tendon adhesion to the graft and reduced range of finger joint movement and contour deformities. We have used this technique in six digits in four patients with successful results.
Origin and transport of tropical cirrus clouds observed over Paramaribo, Suriname (5.8°N, 55.2°W)
Authors: Fortuin J. P. F. , Becker C. R. , Fujiwara M. , Immler F. , Kelder H. M. , Scheele M. P. , Schrems O. , Verver G. H. L.
Published: May 2007

The Intertropical Convergence Zone (ITCZ) passes twice a year over tropical Suriname, bringing two wet and two dry seasons. During a pilot study campaign in Suriname, cirrus clouds were observed with a mobile aerosol Raman lidar (MARL) and with balloon sondes containing a frost point hygrometer called Snow White, over the period October–November 2004. These observations are used to study the origin of cirrus clouds and the dynamical processes that determine their transport, using European Centre for Medium‐Range Weather Forecasts (ECMWF) operational analyses. The height of cirrus occurrence is in phase with the height of the cold point tropopause, with maximum heights occurring during Northern Hemisphere winter that are about 2 km above the minimum values in summertime. The occurrence of cirrus often corresponds with a northerly meridional wind flow (in a layer underneath the tropopause), also when the ITCZ lies to the south in the period January–May. ECMWF analyses point out that inertial instability flow, in the form of vertically stacked meridional circulation cells in the upper troposphere (UT), can explain the transport of these cirrus events. Also evident is that radiative cooling of a moist layer transported in the UT leads to a thermal wind in the form of an easterly/westerly jet associated with the southward/northward transport of moist air. An interactive play between the inertial instability and thermal wind mechanisms explains many of the observed features of cirrus occurrence over Suriname. The observed cirrus mostly originates from the ITCZ or from deep convective centers to the south that form during the early summer monsoon.
Realizing Envisat's potential for rain cloud studies
Authors: Quartly Graham D. , Guymer Trevor H.
Published: May 2007

Owing to the highly variable nature of rain both in space and time and the difficulties in obtaining accurate in situ measurements, increasing reliance is being placed on the various types of satellite data now available. The multi‐sensor payload of Envisat is of particular interest because the data are co‐located and simultaneous, thus reducing some of the uncertainty found in multi‐platform analyses. This paper shows variations in cloud and precipitation data derived from AATSR, RA‐2 and MWR‐2 measurements in an overpass of Hurricane Juan, revealing significant asymmetry in the spatial distribution. The results are discussed in the context of similar data from other tropical and sub‐tropical features in the western Atlantic. The combination of data from these sensors allows us to see the effects of different drop‐size distribution at varying distances from the hurricane's eye and to conclude that active microwave systems are needed for studying small‐scale variations in rainfall.
Processes influencing ozone levels in Alaskan forest fire plumes during long‐range transport over the North Atlantic
Authors: Real E. , Law K. S. , Weinzierl B. , Fiebig M. , Petzold A. , Wild O. , Methven J. , Arnold S. , Stohl A. , Huntrieser H. , Roiger A. , Schlager H. , Stewart D. , Avery M. , Sachse G. , Browell E. , Ferrare R. , Blake D.
Published: May 2007

A case of long‐range transport of a biomass burning plume from Alaska to Europe is analyzed using a Lagrangian approach. This plume was sampled several times in the free troposphere over North America, the North Atlantic and Europe by three different aircraft during the IGAC Lagrangian 2K4 experiment which was part of the ICARTT/ITOP measurement intensive in summer 2004. Measurements in the plume showed enhanced values of CO, VOCs and NOy, mainly in form of PAN. Observed O3 levels increased by 17 ppbv over 5 days. A photochemical trajectory model, CiTTyCAT, was used to examine processes responsible for the chemical evolution of the plume. The model was initialized with upwind data and compared with downwind measurements. The influence of high aerosol loading on photolysis rates in the plume was investigated using in situ aerosol measurements in the plume and lidar retrievals of optical depth as input into a photolysis code (Fast‐J), run in the model. Significant impacts on photochemistry are found with a decrease of 18% in O3 production and 24% in O3 destruction over 5 days when including aerosols. The plume is found to be chemically active with large O3 increases attributed primarily to PAN decomposition during descent of the plume toward Europe. The predicted O3 changes are very dependent on temperature changes during transport and also on water vapor levels in the lower troposphere which can lead to O3 destruction. Simulation of mixing/dilution was necessary to reproduce observed pollutant levels in the plume. Mixing was simulated using background concentrations from measurements in air masses in close proximity to the plume, and mixing timescales (averaging 6.25 days) were derived from CO changes. Observed and simulated O3/CO correlations in the plume were also compared in order to evaluate the photochemistry in the model. Observed slopes change from negative to positive over 5 days. This change, which can be attributed largely to photochemistry, is well reproduced by multiple model runs even if slope values are slightly underestimated suggesting a small underestimation in modeled photochemical O3 production. The possible impact of this biomass burning plume on O3 levels in the European boundary layer was also examined by running the model for a further 5 days and comparing with data collected at surface sites, such as Jungfraujoch, which showed small O3 increases and elevated CO levels. The model predicts significant changes in O3 over the entire 10 day period due to photochemistry but the signal is largely lost because of the effects of dilution. However, measurements in several other BB plumes over Europe show that O3 impact of Alaskan fires can be potentially significant over Europe.
Observational constraints on the chemistry of isoprene nitrates over the eastern United States
Authors: Horowitz Larry W. , Fiore Arlene M. , Milly George P. , Cohen Ronald C. , Perring Anne , Wooldridge Paul J. , Hess Peter G. , Emmons Louisa K. , Lamarque Jean‐François
Published: May 2007

The formation of organic nitrates during the oxidation of the biogenic hydrocarbon isoprene can strongly affect boundary layer concentrations of ozone and nitrogen oxides (NOx = NO + NO2). We constrain uncertainties in the chemistry of these isoprene nitrates using chemical transport model simulations in conjunction with observations over the eastern United States from the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) field campaign during summer 2004. The model best captures the observed boundary layer concentrations of organic nitrates and their correlation with ozone using a 4% yield of isoprene nitrate production from the reaction of isoprene hydroxyperoxy radicals with NO, a recycling of 40% NOx when isoprene nitrates react with OH and ozone, and a fast dry deposition rate of isoprene nitrates. Simulated boundary layer concentrations are only weakly sensitive to the rate of photochemical loss of the isoprene nitrates. An 8% yield of isoprene nitrates degrades agreement with the observations somewhat, but concentrations are still within 50% of observations and thus cannot be ruled out by this study. Our results indicate that complete recycling of NOx from the reactions of isoprene nitrates and slow rates of isoprene nitrate deposition are incompatible with the observations. We find that ∼50% of the isoprene nitrate production in the model occurs via reactions of isoprene (or its oxidation products) with the NO3 radical, but note that the isoprene nitrate yield from this pathway is highly uncertain. Using recent estimates of rapid reaction rates with ozone, 20–24% of isoprene nitrates are lost via this pathway, implying that ozonolysis is an important loss process for isoprene nitrates. Isoprene nitrates are shown to have a major impact on the nitrogen oxide (NOx = NO + NO2) budget in the summertime U.S. continental boundary layer, consuming 15–19% of the emitted NOx, of which 4–6% is recycled back to NOx and the remainder is exported as isoprene nitrates (2–3%) or deposited (8–10%). Our constraints on reaction rates, branching ratios, and deposition rates need to be confirmed through further laboratory and field measurements. The model systematically underestimates free tropospheric concentrations of organic nitrates, indicating a need for future investigation of the processes controlling the observed distribution.
Estimating tidal effects in spring discharge: A multiscale method using correlated phenomena
Authors: Chicken Eric , Loper David E. , Werner Christopher L.
Published: May 2007

Modeling groundwater flow within a coastal karst aquifer is a difficult task because of the influences of rainfall, sinking streams, lunisolar tides, and storm tides. A primary goal of modeling this flow is the accurate simulation of discharge due to rainfall and sinking streams. A necessary preliminary step to accomplish this is to remove from the discharge signal that portion resulting from the influence of tides. This paper presents a new wavelet method for separating these two signals. The statistical concept of correlation is used as a threshold parameter to accomplish the separation.
Microsurgical Fibular Flap for Pelvic Ring Reconstruction after Periacetabular Tumor Resection
Authors: Yu Guangrong , Zhang Feng , Zhou Jiaqian , Chang Shimin , Cheng Liming , Jia Yongwei , Li Haifeng , Lineaweaver William C
Published: May 2007

Reconstruction after resection of tumor about the acetabulum represents a considerable challenge in reconstructive surgery. Between 1999 and 2003, three patients with periacetabular tumors underwent tumor resections (Ennecking type B) and pelvic ring reconstruction with microsurgical fibular flaps. Histological diagnosis showed oseosarcoma, giant cell tumor, and aneurysmoid bone cyst. All patients survived surgery without complications. The follow-up for patients ranged from 14 to 42 months. The average time for bone healing and full weight bearing was 13.6 weeks after surgery. In evaluations of the functional outcome using Enneking scoring system, two reached the score of excellent (≥ 23 points), and one reached the score of good (15 to 22 points). This report shows our experience in use of microsurgical fibular flaps for arthrodesis of the hip after periacetabular tumor resection, which restores the continuity of the pelvic ring with minimal shortening of the limb.
Planar Hall effect in epitaxial thin films of magnetite
Authors: Bason Y. , Klein L. , Wang H. Q. , Hoffman J. , Hong X. , Henrich V. E. , Ahn C. H.
Published: May 2007

We measured the planar Hall effect (PHE) of magnetite (Fe3O4) films between 150 and 350K. The PHE was measured both with a constant magnetic field rotating in the plane of the sample and in a remanent state after applying a field in specific directions. The PHE amplitude decreases with temperature; however, it changes little between 300 and 350K. The remanent PHE signal is as high as 10V∕A, larger than previously observed in manganite films. We also measured the PHE in the remanent state and found that its magnitude and stability make it a viable candidate for magnetic random access memory applications.
Magnetic structure of an Fe–Pd–Rh alloy
Authors: Lin Yin-Chih , Lee H. T. , Jen S. U. , Chen Y. T.
Published: May 2007

Martensitic phase transition in an aged Fe–Pd–Rh alloy was studied using transmission electron microscopy (TEM) and x-ray diffraction. Both TEM and x-ray diffraction reveal the appearance of an intermediate structure between the fcc→L10 martensitic transformation. The intermediate phase, denoted L1m, has a monoclinic structure with lattice parameters of a=3.193Å, b=3.684Å, c=3.141Å, and β=92.042°, and the normal L10 martensitic phase has an ordered structure with lattice parameters of a=3.876Å, c=3.684Å, and c∕a=0.950, as confirmed by TEM and x-ray diffraction.
The Co content and stratification effect on the magnetic properties, microstructure, and phase evolution of [NdFeBNbCu∕Co]∙n thin films
Authors: Chiriac H. , Grigoras M. , Urse M.
Published: May 2007

Some results concerning the magnetic and structural properties of [NdFeBNbCu∕Co]∙n thin films in view of their utilization for manufacturing permanent magnets are presented. As compared to Ta∕NdFeBNbCu∕Ta magnetic single layer, the multilayer Ta∕[NdFeBNbCu∕Co]∙3∕Ta films exhibit good hard magnetic properties and an increase in the Curie temperature due to Nb–Cu addition and stratification effect using Co as spacer layer. The influence of the additions content and the stratification effect on the microstructural and hard magnetic properties of multilayer [NdFeBNbCu∕Co]∙n thin films, when the total thickness of NdFeBNbCu layers was 540nm and the thickness of the Co spacer layers was varied successively from 0to6nm for different annealing conditions, are discussed.
Temperature dependence of tunnel resistance for CoFeB∕MgO∕CoFeB magnetoresistive tunneling junctions: The role of magnon
Authors: Ikegawa Sumio , Aikawa Hisanori , Ueda Tomomasa , Nagamine Makoto , Shimomura Naoharu , Yoshikawa Masatoshi , Hosotani Keiji , Yoda Hiroaki
Published: May 2007

Tunnel resistance for CoFeB∕MgO∕CoFeB junctions with a wide variety of resistance has been investigated as a function of bias voltage Vb and temperature to elucidate bias voltage dependence of the magnetoresistance ratio. Comparison with a conventional NiFe∕AlOx∕CoFe junction is also discussed. In the case of a parallel alignment of the magnetic moments with a MgO barrier, the Vb dependence was much smaller than that of the antiparallel (AP) alignment with a MgO barrier and of both alignment with an AlOx barrier. This probably originates from the unique tunnel mechanism with a MgO barrier: coherent tunneling of Δ1 electron states. In the case of AP alignment with a MgO barrier, distinctive features were observed: temperature coefficient of tunnel resistance steeply decreased with increasing absolute value of Vb at −0.2V<Vb<0.2V. This suggests that inelastic tunneling with excitation of magnon modes plays a crucial role.
Model of phase locking in spin-transfer-driven magnetization dynamics
Authors: Bonin R. , Bertotti G. , Serpico C. , Mayergoyz I. D. , d’Aquino M.
Published: May 2007

A simplified model of phase locking is discussed, which can be fully solved in analytical terms with no limitations as to the intensity of the coupling mechanism responsible for the locking. A nanomagnet with uniaxial symmetry is considered, jointly driven by a spin-polarized current, a dc magnetic field along the symmetry axis, and a radio-frequency circularly polarized magnetic field. The conditions are determined under which locking occurs between current-induced oscillations and the action of the rf field. The locking effect exhibits hysteresis as a function of the current.
Ab initio investigations on atomistic behaviors and magnetic properties in Fe–Cu multilayer system
Authors: Kim Chiho , Chung Yong-Chae
Published: May 2007

Using the density functional theory calculations, the surface diffusion and incorporation processes for Fe–Cu multilayer system were investigated. The minimum energy path calculations revealed that the hollow site of Cu(001) and Fe(001) surfaces was the most stable adsorption site, and the energy barriers for the surface diffusion were 1.04eV for Fe∕Cu(001) and 0.50eV for Cu∕Fe(001) systems. During the process, small fluctuation of magnetic moment, as amount of 0.11μB for Fe adatom and 0.02μB for Cu adatom, was observed. The energy barrier for the incorporation of the Fe adatom into the surface layer of Cu substrate was 0.75eV, and the energy gain of the system was 0.92eV. At the substitutional site, the magnetic moment for Fe adatom was decreased by 2.64μB. The Cu adatom required a relatively small energy barrier, 0.50eV, for incorporation into the Fe substrate; however, it was found that, after the process, the total energy was rather increased by 0.37eV.
Reduced magnetization in magnetic oxide nanoparticles
Authors: Kim T. , Shima M.
Published: May 2007

Magnetic oxide nanoparticles have been studied to elucidate the effects of nanoscale finite size on the magnetic behavior of the particles. Magnetite nanoparticles synthesized by coprecipitation show superparamagnetism at room temperature with reduced saturation magnetization MS. The MS value decreases and approaches zero with decreasing particle size. Yttrium iron garnet (YIG) nanoparticles also show a similar trend. The magnetization of nanoparticles estimated using the Langevin function with the particle size distribution indicates that the reduced magnetization can be consistently explained by the existence of a spin-disordered surface layer with the thickness of 1–2nm. The results found in magnetite and YIG nanoparticles suggest that the reduced magnetization can be commonly observed among magnetic oxide nanoparticles due to the existence of spin disordered surface layer.
Magnetically frustrated behavior in multiferroics RMn2O5 (R=Bi, Eu, and Dy): A Raman scattering study
Authors: García-Flores A. F. , Granado E. , Martinho H. , Rettori C. , Golovenchits E. I. , Sanina V. A. , Oseroff S. B. , Park S. , Cheong S.-W.
Published: May 2007

A temperature dependent Raman scattering study in multiferroic single crystals RMn2O5 (R=Bi, Eu, and Dy) was performed. The Raman spectra were measured in the range from 150to450cm−1 involving mostly Mn–O–Mn bending vibrations, complementing our previous work in a higher frequency range involving Mn–O stretching modes. A number of studied phonons present anomalous frequency behavior below a characteristic temperature, T*∼60–65K, such as that found for the stretching modes. The sign and magnitude of such anomalous behavior appear to be correlated with the ionic radius of R, being softening for R=Bi and hardening for R=Eu and Dy in the range between TC∕TN and T*. The anomalous phonon behaviors in both bending and stretching modes are consistent with an interpretation in terms of the spin-phonon coupling in a scenario of strong magnetic correlations.
Domain observation technique for Nd–Fe–B magnet in high magnetic field by image processing using liquid crystal modulator
Authors: Takezawa M. , Shimada T. , Kondo S. , Mimura S. , Morimoto Y. , Hidaka T. , Yamasaki J.
Published: May 2007

A different domain observation technique by modulation of a polarizing plane has been developed for Nd–Fe–B sintered magnets. A liquid crystal element inserted in a longitudinal Kerr microscope is used as an optical modulator to acquire a reference image needed to enhance Kerr contrast by image processing. Domain images of the Nd–Fe–B magnet can be clearly observed by this technique in a high magnetic field up to 4.4kOe. It was found that polishing of the sintered magnet reduced its coercive force.
High resolution magnetic force microscopy study of e-beam lithography patterned Co∕Pt nanodots
Authors: Belle B. D. , Schedin F. , Pilet N. , Ashworth T. V. , Hill E. W. , Nutter P. W. , Hug H. J. , Miles J. J.
Published: May 2007

E-beam lithography has been used to pattern a continuous Co∕Pt multilayer film with perpendicular anisotropy into circular islands of various sizes down to 25nm diameter on a 60nm pitch. High resolution magnetic force microscopy with in situ applied field has been used to directly determine the switching field distribution (SFD) and hysteresis loop of the islands. For the smallest islands, the coercivity is reduced and the width of the SFD is increased, indicating that they would not be well suited to data storage applications.
Dynamic properties of arrays of ferromagnetic rectangular bars
Authors: Adam Roman , Khivintsev Yuri , Hertel Riccardo , Schneider Claus M. , Hutchison Andrew , Camley Robert , Celinski Zbigniew
Published: May 2007

Dynamic properties of arrays of rectangular bars were studied employing network analyzer ferromagnetic resonance and time-resolved magneto-optic Kerr effect (MOKE) measurements. The bars were patterned on top of coplanar waveguides and oriented with their long axis either parallel or perpendicular to the external magnetic field. Orientation of the bars parallel to the field results in an increase in the resonant frequency by up to ∼2GHz, as well as the linewidth broadening by 0.3–1GHz. The shift is shown to be in agreement with results expected from the difference of demagnetizing factors. The general behavior of the linewidth corresponds to calculations including shape anisotropy; however, the experimentally measured effect is much stronger than expected from theory. Fourier transforms of the time-resolved MOKE signal reveal the presence of several oscillatory modes, associated with the dynamics in the central part and at the borders of ferromagnetic elements.
Magnetization dynamics in CoFe∕AlO/Permalloy and CoFe∕MgO/Permalloy magnetic tunnel junctions
Authors: Finocchio Giovanni , Consolo Giancarlo , Carpentieri Mario , Romeo Antonino , Azzerboni Bruno , Torres Luis
Published: May 2007

This paper presents a theoretical study about the effect of nonidealities in the shape of elliptical cross sectional area of magnetic tunnel junctions on the magnetization dynamics driven by spin-polarized currents (no applied field). The set of nonideal shapes has been computed from scanning electron microscopy images directly. The polarization function deduced by Slonczewski in 2005 [Phys. Rev. B 71, 024411 (2005)] has been used for the simulations, considering the polarization factor independent of the bias. Depending on the shape, results of micromagnetic simulations show that the main steps of the magnetization dynamics do not change qualitatively, but in contrast, (a) other modes (defect modes) are excited, (b) a shift in the excited main mode is observed, and (c) the spatial distribution of the main mode changes.
Array formation and size effects in chemically synthesized FePt nanoparticles
Authors: Colak Levent , Hadjipanayis George C.
Published: May 2007

Monodisperse FePt nanoparticles (NP’s) have been synthesized by reduction of platinum acetylacetonate [Pt(acac)2] followed by thermal decomposition of iron pentacarbonyl [Fe(CO)5] in the presence of oleic acid (OA) and oleyl amine (OY) as surfactants at a low reaction temperature. Particle size is controlled by the injection temperature of Fe(CO)5. The effect of particle size on the blocking temperature has been investigated for nanoparticles with sizes of 3.0 and 6.0nm. The interparticle spacing is varied by changing the addition time of the OA and OY. Well-aligned mono- and multi-layered hexagonal-closed-packed (hcp) to square lattice nanostructures are formed for 5nm FePt NP’s. Surfactant layer thickness, ⟨L⟩ to metal core radius R (⟨L⟩∕R) ratios of 0.46 and 0.60 are evaluated for the monolayer of hexagonal-closed-packed and square lattice array structures, respectively. For hcp arrays bilayer and trilayer structures are also observed. Subjecting the NP’s to thermal processing at 800°C results in a transformation of the nanoparticles from the disordered fcc phase to the ordered L10 phase.
Structure and thermal expansion anomaly study on Nd(Fe,Mo)12Nx
Authors: Du Honglin , Shan Yu , Liu Shunquan , Wang Changsheng , Han Jingzhi , Yang Yingchang , Yue Ming
Published: May 2007

Thermal expansion anomaly studies on Nd(Fe,Mo)12Nx (x=0,0.5,1) compounds were performed by means of x-ray and neutron diffractions. Before nitrogenation, only lattice parameter a shows abnormal thermal expansion below TC. In Nd(Fe,Mo)12N0.5, both parameters a and c show abnormal thermal expansion below TC, while only c shows abnormal thermal expansion in the Nd(Fe,Mo)12N compound. This shows that, with the increase in the N content, the anomaly gradually changes from in the ab plane to along the c axis. By analyzing the Néel curve and the system energy, the anomaly was mainly attributed to the contribution of some strongly positive interactions, which is quite different from the previous explanation for thermal expansion anomalies.
Investigation of the local Fe magnetic moments at the grain boundaries of the Ca2FeReO6 double perovskite
Authors: Azimonte C. , Granado E. , Cezar J. C. , Gopalakrishnan J. , Ramesha K.
Published: May 2007

The local Fe ferromagnetic (FM) moment at the grain boundaries of a ceramic sample of Ca2FeReO6 double perovskite was investigated by means of x-ray magnetic circular dichroism spectroscopy at the Fe L2,3 edges and compared to the overall bulk magnetization. We found that, at the grain boundaries, the Fe FM moments at H=5T are much smaller than expected and that the M×H curve is harder than in the bulk magnetization. These results suggest a larger degree of Fe∕Re antisite disorder at the grain boundaries of this sample, shedding light into the intriguing nonmetallic resistivity behavior despite the reported presence of free carriers.
Partial magnetization reversal in a perpendicular exchange-biased [Pd∕Co]∕FeMn film through laser annealing
Authors: Choi Sang Dae , Joo Ho Wan , Lee Sang Suk , Hwang Do Guwn , Choi Jin Hyup , Lee Ky Am , Kim Sunwook , Bae Seongtae
Published: May 2007

Partial magnetization reversal on the perpendicular exchange-bias characteristics in the [Pd∕Co]×5∕FeMn bilayered and [Pd∕Co]×2∕Cu∕Co∕[Pd∕Co]×2∕FeMn spin valve thin films was investigated using laser. The hysteresis loops were measured using the extraordinary Hall effect and magneto-optical Kerr effect (MOKE). By increasing the output intensity of the laser, the exchange-bias fields in the [Pd∕Co]×5∕FeMn bilayered thin film were gradually changed from negative to positive. The distribution of partial magnetization reversal in the vicinity of the laser spot was measured by using MOKE. Although the magnetic moment of the pinned layer was gradually reversed by using laser annealing in the MOKE loops of the [Pd∕Co]×2∕Cu∕Co∕[Pd∕Co]×2∕FeMn spin valves’ structure, that of the free layer was not changed. When the pattern size was decreased to 5×5μm2, the direction of exchange biasing was fully reversed through laser annealing without distorting the hysteresis loop. All the patterned samples below 100×100μm2 have the same hysteresis loop, and the reversed loops were not distorted and reduced when laser annealing was used.
Field evolution of multivortex and cross-tie states in Permalloy thin films
Authors: Lai Mei-Feng , Wei Zung-Hang , Wu J. C. , Shieh W. Z. , Chang C. R. , Guo J.
Published: May 2007

Field evolution of vortex and cross-tie states is investigated by magnetic force microscopy imaging experimentally. We found that the vortices move perpendicular to the field direction. For the multivortex states, as the external field is perpendicular to the magnetization direction of the rhombic domain, which is enclosed by two neighboring vortices, the rhombic domain tilts. When the external field is parallel/antiparallel to the magnetization direction of the rhombic domain, this domain is extended/contracted. For the cross-tie state, the vortex and antivortex cores annihilate pair by pair in series when the field is applied along the short axis. When the magnetic field is applied along the long axis, the Bloch line moves along the short-axis direction till it, as a whole, annihilates near the edge of the elliptical thin film.
First-principles study on the spin polarization of benzene adsorbed on Fe(100) surface
Authors: Sun X. , Suzuki T. , Kurahashi M. , Zhang J. W. , Yamauchi Y.
Published: May 2007

In this paper, we investigate the spin-resolved electronic states and spin polarization of the benzene adsorbed Fe(100) surface using density functional theory. The existence of the adsorbate-induced π* state and backdonation of the electrons have been demonstrated clearly by the differential charge densities. The calculated plane-averaged density of states of benzene∕Fe(100) in the vacuum side is found to be consistent with the experimental result of spin asymmetry in the spin-polarized metastable-atom deexcitation spectra for pentacene consisting of five benzene rings adsorbed Fe(100) surface.
Isomers of C36 and free energy criteria for cluster growth
Authors: Gao Juan , Lin Zheng-Zhe , Ning Xi-Jing
Published: May 2007

A molecular dynamics procedure is developed to search for cluster isomers and is used to study the isomer spectrum of C36 with the Brenner potential. Beginning with isolated carbon atom, the procedure quickly arrives at the D6h cage with the lowest potential and produces other 410 isomers. Among these isomers, we selected ones of typical cage, bowl, and sheet structures to calculate their free energies at 2300K and performed molecular dynamics simulations starting either from 36 free carbon atoms diluted in He buffer gas kept at 2300K or from the D6h cage under the same conditions, which show that the microsystem reaches a kinetic equilibrium within about 100ns and that the isomer of the lowest free energy rather than the D6h cage of the lowest potential energy dominates in the resultant cluster.
Experimental and theoretical studies of cylindrical Hall thrusters
Authors: Smirnov Artem , Raitses Yegeny , Fisch Nathaniel J.
Published: May 2007

The Hall thruster is a mature electric propulsion device that holds considerable promise in terms of the propellant saving potential. The annular design of the conventional Hall thruster, however, does not naturally scale to low power. The efficiency tends to be lower and the lifetime issues are more aggravated. Cylindrical geometry Hall thrusters have lower surface-to-volume ratio than conventional thrusters and, thus, seem to be more promising for scaling down. The cylindrical Hall thruster (CHT) is fundamentally different from the conventional design in the way the electrons are confined and the ion space charge is neutralized. The performances of both the large (9-cm channel diameter, 600–1000W) and miniaturized (2.6-cm channel diameter, 50–300W) CHTs are comparable with those of the state-of-the-art conventional (annular) design Hall thrusters of similar sizes. A comprehensive experimental and theoretical study of the CHT physics has been conducted, addressing the questions of electron cross-field transport, propellant ionization, plasma-wall interaction, and formation of the electron distribution function. Probe measurements in the harsh plasma environment of the microthruster were performed. Several interesting effects, such as the unusually high ionization efficiency and enhanced electron transport, were observed. Kinetic simulations suggest the existence of the strong fluctuation-enhanced electron diffusion and predict the non-Maxwellian shape of the electron distribution function. Through the acquired understanding of the new physics, ways for further optimization of this means for low-power space propulsion are suggested. Substantial flexibility in the magnetic field configuration of the CHT is the key tool in achieving the high-efficiency operation.
Mechanisms of magnetic-flux penetration into model granular superconductors
Authors: Krasnyuk I. B. , Zalutskiĭ M. V.
Published: May 2007

The process of magnetic-field penetration into a high-temperature granular superconductor occupying the half-space x≥0 is examined. The amplitude of the magnetic field changes at the boundary of the superconductor according to the power-law b(0,t)=b0(1+t∕t0)m, m>0, in normalized variables, where t0 is the time when the scaling behavior is reached. The situation m=1 occurs in the experiments. The superconductor is assumed to be ideal in the sense that the motion of a hypervortex with velocity v(j,b) (where j=J∕Jc, Jc is the critical current density) determines the only dissipative process of the viscous flow of vortices and the creation-annihilation of vortices is neglected. It is shown that the evolution of the amplitude of the magnetic field satisfies the well-known equation of a porous medium, or the Boussinesq equation with convection. A self-similar solution is obtained for the initial-boundary value problem. Analytical relations are obtained for the coordinate of the magnetic wavefront and the penetration rate of the magnetic field which depend on the pump parameter m and the parameters of the granular superconductor (for example, the Josephson penetration depth and the critical current density). A criterion is given for the appearance of thermomagnetic instabilities with a nonmonotonic dependence of the critical field on the amplitude of the magnetic field (peak effect). Quantitative estimates are given for the lowest rate of appearance of dendritic structure. The results obtained are compared with experiments for a plane-parallel plate in a perpendicular magnetic field that increases with time.
Characteristics of the magnetic ordering of Fe∕Au∕Tb multilayer films
Authors: Kalita V. M. , Lozenko A. F. , Ryabchenko S. M. , Trotsenko P. A. , Shipil E. V. , Pogorelyĭ A. N.
Published: May 2007

Temperature and field investigations of the magnetic properties of multilayer films, consisting of a sequence of alternating magnetic layers of iron and the rare-earth terbium separated by layers of nonmagnetic gold, are performed. The samples were obtained by electron-beam deposition. The field dependence of the magnetic moment of a film with H∥n are analyzed to determine the characteristics of the uniaxial anisotropy. It is shown that a nonuniform uniaxial anisotropy results in nonlinearity in the magnetization of the film in H∥n. The process of magnetization of a film in H⊥n, when the transition to a single-domain state occurs only as a result of the motion of domain walls, is described. It is shown on the basis of the data on the field dependences of the magnetic moment at low temperatures that the magnetic moments of the Fe and Tb layers are oriented oppositely with respect to one another. A compensation point is observed in the temperature dependence of the magnetization; this indicates the presence of antiferromagnetic coupling between the Fe and Tb layers.
de Haas–van Alphen effect in the diborides ScB2, ZrB2, and HfB2
Authors: Pluzhnikov V. B. , Svechkarev I. V. , Dukhnenko A. V. , Levchenko A. V. , Filippov V. B. , Chopnik A.
Published: May 2007

ScB 2 , ZrB2, and HfB2 single crystals with hexagonal structure were grown and the properties of the Fermi surface of these compounds were studied using the de Haas–van Alphen effect (dHvA). The angular dependences of the frequencies of the dHvA oscillations in the planes (101¯0), (112¯0), and (0001) and the values of their effective cyclotron masses were measured. The frequencies of the oscillations found lie in the interval (0.96–28.2)×102T and the measured cyclotron masses lie in the range (0.09–0.87)m0. The values of the electron–phonon interaction constant λ on different sections of Fermi surface of ZrB2 were determined. The value of the constant λ ranges from 0.05–0.16.
Rayleigh envelope solitons near a surface with a nonlinear film coating
Authors: Kovalev A. S. , Sokolova E. S.
Published: May 2007

The dynamics of Rayleigh envelope solitons localized near the surface of a uniform isotropic elastic medium coated with a thin layer of a nonlinear (anharmonic) material are investigated. A variant of an asymptotic procedure for finding an approximate analytical solution for such solitons is proposed.
Low temperature characterization of heated microcantilevers
Authors: Park Keunhan , Marchenkov Alexei , Zhang Zhuomin M. , King William P.
Published: May 2007

This article describes the electrical and thermal behaviors of heated atomic force microscope cantilevers under steady- and periodic-heating operation at low temperatures and in vacuum. The cantilever resistance drastically increases as temperature decreases below 150 K, providing a large and negative temperature coefficient of resistance of −0.023 K−1 at 100 K. Under steady heating, the cantilever heater can be heated above 300 K even when its environment is at 77 K. Electrical and thermal transfer functions are derived to depict the electrical and thermal cantilever responses under periodic heating and to extract cantilever thermophysical properties. The calculation of in-phase and out-of-phase temperatures along the cantilever reveals that its response becomes out of phase and restricted to the heater region at high frequencies. These results enable the use of heated cantilevers in cryogenic applications as a localized heat source and a sensitive thermal metrology tool.
In situ Raman spectroscopy of low-temperature/high-pressure transformations of H2O
Authors: Yoshimura Yukihiro , Stewart Sarah T. , Mao Ho-kwang , Hemley Russell J.
Published: May 2007

In situ Raman spectra of transformations of H2O as functions of pressure and temperature have been measured starting from high-density amorphous ice (HDA). Changes above Tx, the crystallization temperature of HDA, were observed. The spectra provide evidence for an abrupt, first-order-like, structural change that appears to be distinct from those associated with the transformation between low-density amorphous ice (LDA) and HDA. In separate experiments, in situ Raman spectra of ice XII transformed from HDA have been measured at various P-T regions, in order to improve the understanding of the stability limits of ice XII. The spectra of ices VI and XII differ in shape, but the vibrational frequencies are very close in the same P-T regimes. A metastable phase of ice found to form within the stability field of ice VI appears to be distinct from ice XII.