bluuebunny/crossref_metadata_2025 huggingface dataset:
Adipositas im Kindes- und Jugendalter:
Authors: Warschburger Petra , Kröller Katja
Published: May 2005

Zusammenfassung. Adipöse Kinder und Jugendliche gelten als Risikogruppe für die Entwicklung von psychosozialen Belastungen, den Einsatz von gesundheitsschädigenden Gewichtskontrollmaßnahmen sowie auffällige Essverhaltensweisen. Dennoch ist relativ wenig über das Auftreten von Heißhungerattacken (“binging“) und Binge Eating Disorder (BED) bei dieser Gruppe bekannt. Die folgende Studie untersuchte bei 156 adipösen Kindern und Jugendlichen (im Alter zwischen 11 und 18 Jahren) die selbstberichtete Verbreitung von “binging“ und BED. Im zweiten Schritt wurde untersucht, inwieweit sich “Binger“ von “non-Bingern“ in der Störbarkeit ihres Essverhaltens, ihrem Selbstkonzept, dem Erleben von Hänseleien und dem Umgang damit unterscheiden, wobei eine erhöhte Auffälligkeit der Binger vermutet wurde. Die Kinder beantworteten ein Fragebogenpaket mit folgenden Instrumenten: QEWP-A (essgestörtes Verhalten), POTS (Hänseleien), Auslöser für Essverhalten, Fragebogen zur Problembewältigung und FSK-K (Selbstkonzept). Die Auftretenshäufigkeit der BED lag bei 3.8%. Insgesamt berichteten jedoch 12.8% der Kinder und Jugendlichen (sog. Binger) von Heißhungerattacken. Diese Gruppe unterschied sich von den non-Bingern weder im Alter, noch im BMI oder in der Geschlechtsverteilung. Erwartungsgemäß berichteten die Binger über eine höhere Auslösbarkeit von Essverhalten sowie ein häufigeres Auftreten von gewichtsbezogenen Hänseleien, unter denen sie auch angaben, vermehrt zu leiden. Beim Umgang mit solchen Hänseleien benutzten Binger darüber hinaus häufiger vermeidende Strategien. Keine Gruppenunterschiede wurden im Selbstwert, der erlebten Attraktivität und schulischen Kompetenz gefunden. Vermeidender Bewältigungsstil sowie hohe Störbarkeit des Essverhaltens erwiesen sich als bedeutsam zur Vorhersage der Gruppenzugehörigkeit. Die Ergebnisse wurden in Bezug auf die Bedeutung von Hänseleien und deren Bewältigung diskutiert.
Optical Topography with Near-Infrared Spectroscopy During a Verbal-Fluency Task
Authors: Herrmann M.J. , Ehlis A.-C. , Scheuerpflug P. , Fallgatter A.J.
Published: May 2005

Abstract: In this study we investigated the changes in brain oxygenation in 22 subjects during a verbal fluency task (VFT) using multichannel near-infrared spectroscopy (NIRS). To assess topographical effects in more detail we measured over bilateral prefrontal and over the left frontolateral cortex in 11 subjects. We found significantly higher increases in O2HB, as a sign of cerebral activation, during the VFT compared to a verbal repetition control task over the left prefrontal and the inferior left lateral brain areas. These results underscore the value of NIRS to assess functional brain activation during cognitive tasks. Furthermore, it shows the advantage of multichannel compared to previously used single channel NIRS measurements.
Arousal and Activation in a Continuous Performance Task
Authors: Barry Robert J. , Clarke Adam R. , McCarthy Rory , Selikowitz Mark , Rushby Jacqueline A.
Published: May 2005

Abstract: The concepts of arousal and activation have had a confused history in Psychophysiology, and there is no widely accepted consensus on their usefulness in the field. This study aimed to explore whether these concepts could be separated in terms of their effects on the phasic Orienting Response (OR) and behavioral performance. We defined arousal at a particular time to be the energetic state at that time, reflected in electrodermal activity and measured by skin conductance level. Task-related activation was defined as the change in arousal from a resting baseline to the task situation. A continuous performance task was used with normal children. The magnitude of the mean phasic OR elicited by target stimuli was dependent on arousal, but not on task-related activation. Two performance measures (mean reaction time and number of errors) improved with increasing activation, but not with arousal. These data suggest the value of conceptualizing arousal and activation as separable aspects of the energetics of physiological and behavioral responding in future studies of attention, cognition, and emotion.
Estimates of the suprathermal O+ outflow characteristic energy and relative location in the auroral oval
Authors: Andersson L. , Peterson W. K. , McBryde K. M.
Published: May 2005

We have surveyed one year of northern hemisphere data from the FAST satellite and obtained the first global estimates of the characteristic energy of the energetic oxygen ion outflows and their relative distribution within the auroral oval. Recent results have shown that, above ∼3,000 km, the FAST/TEAMS instrument covers the energy range that includes almost all of the escaping O+. The highest mean characteristic O+ energy is found at the poleward edge of the night‐side auroral oval. Our results suggest that the energization and/or transport are operating differently in the noon, dusk, midnight and dawn sectors of the auroral oval. The results presented here also provide required ground truth and boundary conditions for global modeling.
Salinity variability in the Arabian Sea
Authors: Joseph Sudheer , Freeland Howard J.
Published: May 2005

Argo floats deployed in the Arabian Sea provided an opportunity to look at the temporal variability of the core‐depth of Arabian Sea High Salinity Water mass (ASHSW) at three locations in the north, central and southern Arabian Sea. These three locations show distinctly different variability patterns. At the northern location we see a prominent semi‐annual cycle, whereas at the central location an annual cycle dominates. Comparison with TOPEX/JASON sea level data shows that this difference can be attributed to the influence of Rossby waves at the central location. In the southern Arabian Sea the variability in core depth is also dominated by an annual‐mode, but there are 2 high frequency components near the Madden‐Julian Oscillation frequencies. Thus the salinity distribution in the Arabian Sea apparently is influenced by both remote forcing and ocean atmospheric coupling.
Effect of glutamate receptor antagonists on place aversion induced by naloxone in single‐dose morphine‐treated rats
Authors: Kawasaki Yoichi , Jin Chunyu , Suemaru Katsuya , Kawasaki Hiromu , Shibata Kazuhiko , Choshi Tominari , Hibino Satoshi , Gomita Yutaka , Araki Hiroaki
Published: May 2005

The neurobiological mechanism underlying the negative motivational component of withdrawal from acute opiate dependence is far from understood.

Our objectives were to determine whether the glutamatergic system is involved in the motivational component of morphine withdrawal in acutely dependent rats and such an involvement is associated with dopaminergic neurotransmission.

We examined the effects of various kinds of glutamate receptor antagonists on conditioned place aversion (CPA) induced by naloxone‐precipitated withdrawal from a single morphine exposure 24 h before. Furthermore, the influence of pretreatment with the dopamine receptor antagonist haloperidol on those effects of glutamate receptor antagonists was also investigated.

CPA was attenuated in a dose‐dependent manner by all glutamate receptor antagonists examined including the NMDA receptor antagonists (+)‐5‐methyl‐10,11‐dihydro‐5H‐dibenzo[a,d]cyclo‐hepten‐5,10‐imine maleate (MK‐801) and phencyclidine hydrochloride (PCP), AMPA receptor antagonist 1‐(4‐aminophenyl)4‐methyl‐7,8‐methylenedioxy‐5H‐2,3‐benzodiazepine hydrochloride (GYKI 52466), and metabotropic receptor antagonists (±)‐2‐amino‐3‐phosphonopropionic acid (AP‐3) and (±)‐α‐methyl‐4‐carboxyphenylglycine (MCPG). The effects of MK‐801, GYKI 52466 and MCPG were blocked by haloperidol.

These results suggest that the glutamatergic system involving multiple classes of receptors plays a role in the motivational component of withdrawal from acute morphine dependence, and the function of the glutamatergic system would be closely associated with dopaminergic neurotransmission.

British Journal of Pharmacology (2005) 145, 751–757. doi:10.1038/sj.bjp.0706228
Effect of serum withdrawal on the contribution of L‐type calcium channels (CaV1.2) to intracellular Ca2+ responses and chemotaxis in cultured human vascular smooth muscle cells
Authors: Patel Mahendra K , Clunn Gerard F , Lymn Joanne S , Austin Oneka , Hughes Alun D
Published: May 2005

Vascular smooth muscle cell (VSMC) chemotaxis is fundamental to atherosclerosis and intimal hyperplasia. An increase in intracellular Ca2+ [Ca2+]i is an important signal in chemotaxis, but the role of L‐type calcium channels (CaV1.2) in this response in human vascular smooth muscle cells (hVSMC) has not been examined.

hVSMC were grown from explant cultures of saphenous vein. Confluent hVSMC at passage 3 were studied after culture in medium containing 15% foetal calf serum (FCS) (randomly cycling) or following serum deprivation for up to 7 days. Smooth muscle α‐actin was measured by immunoblotting and immunofluorescence microscopy. [Ca2+]i was measured using fura 2 fluorimetry. Chemotaxis was measured using a modified Boyden chamber technique and cell attachment to gelatin‐coated plates was also quantified. The number and affinity of dihydropyridine‐binding sites was assessed using [5‐methyl‐3H]PN 200‐110 binding.

In randomly cycling cells, the calcium channel agonist, Bay K 8644a and 100 mM KCl did not affect [Ca2+]i. In addition, the rise in [Ca2+]i induced by platelet‐derived growth factor‐BB (PDGF) was unaffected by the CaV1.2 antagonists, amlodipine and verapamil. In randomly cycling cells amlodipine did not affect PDGF‐induced migration.

In serum‐deprived cells, smooth muscle α‐actin was increased and Bay K 8644a and 100 mM KCl increased [Ca2+]i. PDGF‐induced rises in [Ca2+]i were also inhibited by amlodipine and verapamil. The ability of Bay K 8644a to increase [Ca2+]i and verapamil to inhibit PDGF‐induced rises in [Ca2+]i was evident within 3 days after serum withdrawal. In serum‐deprived hVSMC Bay K 8644a induced chemotaxis and amlodipine inhibited PDGF‐induced migration. Cell attachment in the presence of PDGF was unaffected by amlodipine in either randomly cycling or serum‐deprived hVSMC.

Serum withdrawal was associated with a decrease in the maximum number of dihydropyridine‐binding sites (Bmax) and a decrease in affinity (KD).

Serum deprivation of hVSMC results in increased expression of smooth muscle α‐actin, a marker of more differentiated status, and increased [Ca2+]i responses and chemotaxis mediated by CaV1.2. These observations may have important implications for understanding the therapeutic benefits of calcium channel antagonists in cardiovascular disease.

British Journal of Pharmacology (2005) 145, 811–817. doi:10.1038/sj.bjp.0706237
Pomegranate flower improves cardiac lipid metabolism in a diabetic rat model: role of lowering circulating lipids
Authors: Huang Tom Hsun‐Wei , Peng Gang , Kota Bhavani Prasad , Li George Qian , Yamahara Johji , Roufogalis Basil D , Li Yuhao
Published: May 2005

Excess triglyceride (TG) accumulation and increased fatty acid (FA) oxidation in the diabetic heart contribute to cardiac dysfunction. Punica granatum flower (PGF) is a traditional antidiabetic medicine. Here, we investigated the effects and mechanisms of action of PGF extract on abnormal cardiac lipid metabolism both in vivo and in vitro.

Long‐term oral administration of PGF extract (500 mg kg−1) reduced cardiac TG content, accompanied by a decrease in plasma levels of TG and total cholesterol in Zucker diabetic fatty (ZDF) rats, indicating improvement by PGF extract of abnormal cardiac TG accumulation and hyperlipidemia in this diabetic model.

Treatment of ZDF rats with PGF extract lowered plasma FA levels. Furthermore, the treatment suppressed cardiac overexpression of mRNAs encoding for FA transport protein, peroxisome proliferator‐activated receptor (PPAR)‐α, carnitine palmitoyltransferase‐1, acyl‐CoA oxidase and 5′‐AMP‐activated protein kinase α2, and restored downregulated cardiac acetyl‐CoA carboxylase mRNA expression in ZDF rats, whereas it showed little effect in Zucker lean rats. The results suggest that PGF extract inhibits increased cardiac FA uptake and oxidation in the diabetic condition.

PGF extract and its component oleanolic acid enhanced PPAR‐α luciferase reporter gene activity in human embryonic kidney 293 cells, and this effect was completely suppressed by a selective PPAR‐α antagonist MK‐886, consistent with the presence of PPAR‐α activator activity in the extract and this component.

Our findings suggest that PGF extract improves abnormal cardiac lipid metabolism in ZDF rats by activating PPAR‐α and thereby lowering circulating lipid and inhibiting its cardiac uptake.

British Journal of Pharmacology (2005) 145, 767–774. doi:10.1038/sj.bjp.0706245
Thickness dependence of magnetic anisotropy in thin Ni films electrodeposited onto the (011) and (001) surfaces of n-GaAs
Authors: Gubbiotti G. , Carlotti G. , Tacchi S. , Liu Y.-K. , Scheck C. , Schad R. , Zangari G.
Published: May 2005

Brillouin light scattering from thermal spin waves has been exploited to investigate the thickness dependence of magnetic anisotropy of Ni films, with thickness in the range 7–35nm, grown by electrodeposition onto either (011)- or (001)-GaAs substrates. In the former case, Ni films exhibit a well-defined in-plane uniaxial anisotropy induced by the symmetry of the substrate. In the case of the (001)-GaAs substrate, instead, the magnetic anisotropy results from a combination of both a fourfold and a twofold contribution. The physical mechanisms responsible for the observed anisotropy, as well as its dependence on film thickness, are discussed in detail.
Local structure and destruction of electron pathway effects on Curie temperature of B-site-substituted lanthanum manganites
Authors: Ulyanov A. N. , Yu Seong-Cho
Published: May 2005

A study of B-site-substituted La0.7Ca0.3Mn1−xScxO3 lanthanum manganites is presented. Substitution of Sc3+ ion for Mn3+ ion damages a path of motion of itinerant eg electrons, thus causing a weakening of double-exchange interaction and a decrease of Curie temperature, TC (about 35K for each 1% Sc doping from x=0 to 0.03). We suggest that the observed strong decrease of the TC with x is mostly caused by a difference in an electron configuration of the Mn3+ and Sc3+ ions and partially due to a change in the local parameters of the MnO6 octahedra because of the larger Sc3+ ion than the Mn3+ one. A method for distinguishing the effect of the above two factors on Curie temperature is supposed.
Mn magnetic ordering in fully oxygenated Lu1−xScxMnO3 (x=, 0.5, and 1)
Authors: Huang P. J. , Wu S. Y. , Tsao F. C. , Yang C. C. , Chung M. K. , Li W.-H. , Lynn J. W. , Ku H. C.
Published: May 2005

The magnetic properties of fully oxygenated hexagonal Lu1−xScxMnO3 (x=0, 0.5, and 1) have been investigated by means of neutron diffraction and ac magnetization measurements. All three compounds crystallized into a hexagonal symmetry of space-group P63cm. No structural changes were observed between 10 and 300 K. Anomaly of antiferromagnetic characters was observed at ∼90, 95, and 126 K for the x=0, 0.5, and 1 compounds, respectively, in the temperature dependence of the ac magnetic susceptibility, signaling the ordering of the Mn spins. Both the ferromagnetic and antiferromagnetic components, associated with the Mn spins, were revealed in the low-temperature neutron magnetic diffraction patterns. The observed magnetic intensities are consistent with a magnetic structure that can be described by using the Kovalev Γ5 irreducible representation, where the Mn moments lie in the basal MnO2 planes and the couplings between the adjacent MnO2 planes are ferromagnetic, with a saturated moment of ⟨μz⟩=3.22(3)μB and 3.15(3)μB for the x=0 and 0.5 compounds, respectively.
Sputtered FePt films with uniform nanoscale grain size on Cu (001) single crystal
Authors: Sun C. J. , Liu B. H. , Wang J. P. , Chow G. M.
Published: May 2005

The grain size and grain-size distribution of sputtered L10 Fe50Pt50 (300Å thick, composition in at. %) magnetic thin films on Cu (001) single-crystal substrate were investigated using high-resolution transmission electron microscopy (HRTEM). The planar TEM results showed that the grain size was about 56Å in diameter with a standard deviation of ∼10%. The cross-sectioned TEM images indicated that the magnetic grains existed in columnar structures. The L10-ordered FePt films with a small grain size and narrow grain-size distribution are potential media candidates for the high-areal density magnetic recording.
Electronic and magnetic ordering induced by Mo- and Ru doping of the Mn site in CaMnO3 perovskite: EMR probing
Authors: Shames A. I. , Auslender M. , Rozenberg E. , Gorodetsky G. , Martin C. , Maignan A.
Published: May 2005

X-band electron magnetic-resonance (EMR) measurements of polycrystalline CaMn1−yMoyO3 (0⩽y⩽0.14) samples were performed at 120K⩽T⩽540K. The data obtained are compared with those of another electron-doped manganite system, CaMn1−xRuxO3 (0⩽x⩽0.40). The observed anomalies of the EMR parameters correlate pretty well with the temperatures of antiferro-, ferromagneticlike, and orbital/charge-ordering transitions in these systems. However, a strong difference is observed between the resonant properties of Mo- and Ru doped series at both paramagnetic (PM) and magnetically ordered states. To describe such a difference, the energy-band diagrams, which comprise the deep impurity t2g-like states +eg-like conductive band for CaMn1−xRuxO3 and shallow impurity states+conductive band, both having eg-like symmetry, for CaMn1−yMoyO3, are proposed. Specific electrons’ contribution to the EMR linewidth at PM temperatures is introduced for the considered systems.
Low-frequency magnetization processes in chemically etched Co-based amorphous ribbons
Authors: Betancourt I. , Martinez L. A. , Valenzuela R.
Published: May 2005

In this report we present a study of the magnetization processes for Co-based amorphous ribbons at low frequencies (10 Hz–13 MHz) as a function of decreasing thicknesses attained by chemical etching. Reversible domain-wall bulging, characterized by initial permeability and relaxation frequency, was monitored by means of inductance measurements. The real part of inductance (proportional to initial permeability) exhibited a decreasing trend with diminishing ribbon thickness, together with an increasing tendency for the relaxation frequency. For high amplitude of the ac field (leading to domain-wall unpinning), reduced ribbon thickness showed a deleterious-enhancement effect on irreversible domain-wall displacement, which was observed for both real and imaginary inductance spectrocopic plots. Results are interpreted in terms of reduced domain-wall pinning distances resulting from thinner alloy samples.
Temperature dependent magnetic properties of a Co∕Pd multilayer thin film
Authors: Imai Susumu , Inaba Nobuyuki , Awano Hiroyuki , Ota Norio
Published: May 2005

This article presents a theoretical model for the temperature dependent magnetic properties for a Co∕Pd multilayer thin film medium assuming virtual interface (VIF). We assume that the exchange integral for the Co-VIF interaction is 1.38 times the exchange integral for the Co-Co interaction. Based on the mean field theory, temperature dependences of the average Co spin, the virtual interface spin, saturation magnetization Ms and exchange stiffness constant A are presented for the [Co(0.2nm)∕Pd(0.8nm)]12 multilayer thin film. Fairly good agreement in Ms between the simulations and the experiments suggests validity in the temperature dependence of A.
Magnetic properties of Nd–Fe–Co–Ga–B magnets produced by spark plasma sintering method
Authors: Saito Tetsuji , Takeuchi Tomonari , Kageyama Hiroyuki
Published: May 2005

Amorphous Nd–Fe–Co–Ga–B melt-spun ribbons were consolidated into bulk materials by the spark plasma sintering method. The resultant bulk materials were amorphous when the ribbons were consolidated below the crystallization temperature. On the other hand, the bulk materials consisted of the Nd2Fe14B phase when the ribbons were consolidated just above the crystallization temperature. The resultant magnets had high coercivities but were magnetically isotropic. Alignment of the Nd2Fe14B phase in the bulk materials was achieved by increasing the applied pressure. The resultant anisotropic magnets exhibited a high remanence of 12kG and a high coercivity of 15kOe.
Effect of substrate inclination on the magnetic anisotropy of ultrathin Fe films grown on Al2O3(0001)
Authors: Shiratsuchi Yu , Endo Yasushi , Yamamoto Masahiko , Bader S. D.
Published: May 2005

We have investigated the effect of substrate inclination on the in-plane magnetic anisotropy of ultrathin Fe films grown on Al2O3(0001). For Fe films grown on flat Al2O3 substrates, no preferred direction of magnetization exists in the film plane due to the three equivalent epitaxial orientations of Fe(110) that form. However, for Fe grown on an inclined Al2O3 substrate, a uniaxial anisotropy appears that is parallel to the step edges. The anisotropy increases in magnitude with decreasing Fe thickness and growth temperature, and as the surface morphology changes from being rough to being smooth. We attribute the uniaxial anisotropy to the effective demagnetization field caused by the surface corrugation.
Epitaxial La0.67Sr0.33MnO3∕La0.67Ba0.33MnO3 superlattices
Authors: Belenky Land J. , Ke Xianglin , Rzchowski Mark , Eom C. B.
Published: May 2005

Artificially layered superlattices allows manipulation of strain and the study of dimensional crossover by introducing additional degrees of freedom not found in bulk materials. Superlattices of the colossal magnetoresistive materials, La0.67Sr0.33MnO3 (LSMO) and La0.67Ba0.33MnO3 (LBMO) have been grown by pulsed laser deposition with high-pressure in situ reflection high-energy electron diffraction on (001) SrTiO3 substrates. X-ray diffraction shows several sets of superlattice peaks indicating 90Å periodicity. A high Tc for the LSMO and independent switching of LSMO and LBMO at low temperatures is found.
Magnetoresistive effects in ferromagnet-superconductor multilayers
Authors: Stoudenmire E. M. , Sá de Melo C. A. R.
Published: May 2005

We consider a nanoscale system consisting of manganite-ferromagnet and cuprate-superconductor multilayers in a spin-valve configuration. The magnetization of the bottom manganite ferromagnet is pinned by a manganite antiferromagnet. The magnetization of the top manganite ferromagnet is coupled to the bottom one via indirect exchange through the superconducting layers. We study the behavior of the critical temperature and the magnetoresistance as a function of an externally applied parallel magnetic field, when the number of cuprate-superconductor layers are changed. There are two typical behaviors in the case of a few monolayers of the cuprates: (a) for small magnetic fields, the critical temperature and the magnetoresistance change abruptly when the flipping field of the top manganite ferromagnet is reached, and (b) for large magnetic fields, the multilayered system reenters the zero-resistance (superconducting) state after having become resistive (normal).
Effect of lattice mismatch on chemical ordering of epitaxial L1 FePt films
Authors: Ding Y. F. , Chen J. S. , Liu E. , Sun C. J. , Chow G. M.
Published: May 2005

The effect of lattice mismatch on the chemical ordering of epitaxial FePt films was studied. The results showed that the lattice constant (c) of the FePt films decreased with increasing lattice mismatch ε from about 2.23% to 6.33%. Upon further increase of ε to about 8.8%, c increased. On the other hand, the variation of the lattice constant (a) of the FePt films showed a reversal behavior to that of c with the increased lattice mismatch. The ratio c∕a of the FePt films held a minimum of about 0.9466, while the chemical ordering degree and magnetic anisotropy constant held maximum values for ε around 6.33%. These results indicated that the strain from the lattice mismatch favored the ordering of the FePt films.
Effects of forming gas annealing on low-temperature ordering of FePt films
Authors: Lai Chih-Huang , Wu Yun-Chung , Chiang Chao-Chien
Published: May 2005

FePt Films with a large coercivity of as high as 7700Oe were obtained after forming-gas annealing at 275°C. The coercivity was further increased to 13500Oe by annealing at 400°C. Hydrogen atoms may occupy the interstitial sites of FePt, inducing a local strain or an agitation to accelerate the ordering of FePt. The (111) d-spacing of FePt depends not only on the degree of ordering but also on the amount of hydrogen atoms. The coercivity increased with the amount of hydrogen atoms dissolved in the FePt lattices. The coercivity of FePt films annealed in the forming gas also depended strongly on the thickness.
Determination of multiple easy axes in magnetic multilayers by remanence measurement using a vector magnetometer
Authors: Zhu F. Q. , Chien C. L.
Published: May 2005

The determination of multiple easy axes in magnetic multilayers with noncollinear spin structures using traditional hysteresis loop measurements at different angles is time consuming and problematic. We describe a simple and accurate method for determining the easy axis and remnant magnetization of each individual magnetic layer. By measuring the angular dependence of the x component of the remnant magnetization using a vector vibrating sample magnetometer and numerical fitting based on superposition of the remnant magnetizations, multiple easy axes can be determined with a resolution of about 0.1°. We demonstrate that multilayer samples with one, two, or even three easy axes can be determined with only one measurement of angular dependent remanence.
Magnetic properties and L1 phase formation of FePt films prepared by high current-density ion-beam irradiation and rapid thermal annealing methods
Authors: Yokota T. , Yan M. L. , Xu Yingfan , Gao L. , Zhang R. , Nicholl L. , Yuan L. , Skomski R. , Sellmyer D. J. , Liou S. H. , Lai Chih-Huang , Yang Cheng-Han , Huang Sheng-Huang
Published: May 2005

We investigated magnetic properties and L10 phase formation of FePt films by rapid thermal annealing (RTA) and high current-density ion-beam irradiation. The sample prepared by RTA at 550°C has (001) texture and strong magnetic perpendicular anisotropy with Hc equal to 6kOe. The sample irradiated at 5.04μA∕cm2 has Hc equal to 10kOe but has isotropic magnetic properties due to the (111) texture. The magnetic correlation length of the ion-irradiated sample was about twice as large as that of the RTA sample. This may be due to the inhomogeneity of the L10 phase formation in the ion-irradiated film.
Effect of Zr substitution on microstructure and magnetic properties of YDy-based R2Fe14B magnets (R=Y+Dy+Nd)
Authors: Tang W. , Wu Y. Q. , Dennis K. W. , Kramer M. J. , Anderson I. E. , McCallum R. W.
Published: May 2005

The effect of Zr substitution on the microstructure and magnetic properties in [Nd0.5(YDy)0.25]2.2−xZrxCo1.5Fe12.5B (x=0–0.7) ribbons melt spun at a wheel speed of 10m∕s has been systematically studied. For as-spun Zr-free ribbon, a coercivity Hcj of 15.5kOe is obtained but the demagnetization curve exhibits a large shoulder, resulting in a very low maximum energy product (BH)max(3MGOe). With increasing Zr content (x), Hcj first decreases and then increases. When x=0.4, both Hcj and (BH)max reach their optimized values of 10.6kOe and 9.6MGOe, respectively. The Hcj and (BH)max for the sample at 200°C are 5kOe and 4.3MGOe, respectively. Transmission electron microscopy characterizations show that the average grain size is 200, 65, and 50nm for x=0, 0.4, and 0.7, respectively, indicating that the substitution of Zr can effectively inhibit grain growth. However, an excessive substitution of Zr results in the appearance of the 2:17 phase and thus the reduction of magnetic properties.
Magnetic properties and microstructure of nanocomposite Pr2Fe14(B,C)∕α-Fe melt-spun ribbons
Authors: Sun Y. L. , Chiu C. H. , Chang C. W. , Chang H. W. , Chang W. C.
Published: May 2005

The phase evolution, microstructure, and magnetic properties of melt-spun Pr11Febal.B8−xCx (x=0–8) and Pr11Febal.Co10B6C2 nanocomposites have been investigated. Summarizing the results of x-ray diffraction and thermal magnetic analysis for Pr11Febal.B8−xCx series ribbons, magnetically soft Fe3B and α-Fe phases are found to coexist with magnetically hard 2:14:1 phase for carbon-free (x=0) ribbons; three phases, namely, 2:14:1, Pr2Fe17Cy, and α-Fe, appear for x=2–6, while 2:14:1 phase is almost not formed in Pr11Febal.C8 ribbons. The optimal magnetic properties of Br=9.4kG, Hci=9.3kOe, and (BH)max=17.3MGOe are obtained in Pr11Febal.B6C2. Substitution of 10at.% Co for Fe in Pr11Febal.B6C2 ribbons refines the grain size of the existing 2:14:1, Pr2Fe17Cy, and α-(Fe,Co) phases and enhances the magnetic properties of the ribbons to Br=9.8kG, Hci=10.4kOe, (BH)max=19.0MGOe.
Microstructure and hard magnetic properties of directly synthesized L1(Fe1−xPtx)78Zr4B18 nanocrystalline alloys by melt spinning
Authors: Bitoh T. , Makino A. , Nakagawa M.
Published: May 2005

The microstructure and the hard magnetic properties of the melt-spun (Fe1−xPtx)78Zr4B18 (x=0.385, 0.45, 0.50, and 0.55) nanocrystalline alloys have been investigated. The ordered L10-FePt phase with a grain size smaller than the critical single domain size is directly formed by rapidly quenching of the alloy melt with x=0.45 and 0.50. The alloys have a mixed microstructure composed of the L10-FePt and fcc phases, and exhibit high coercivity (Hc) of 649 and 688kA∕m, respectively, in an as-quenched state. On the other hand, the alloys with x=0.385 and 0.55 are found to composed of two fcc phases and fcc+L12-FePt3+L10-FePt, respectively, and exhibit Hc values lower than 70kA∕m in an as-quenched state. The rapidly quenching of the melt of the (Fe1−xPtx)78Zr4B18 alloys with x=0.45–0.50 is useful to realize the good hard magnetic properties through the grain size refinement of the near equiatomic FePt alloys.
Electronic phase separation in (La1∕3Sm2∕3)2∕3A1∕3MnO3 (A=Ca, Sr and Ba) compounds
Authors: Asthana Saket , Bahadur D. , Nigam A. K. , Malik S. K.
Published: May 2005

Electrical and magnetotransport properties of (La1∕3Sm2∕3)2∕3A1∕3MnO3 (A=Ca, Sr, and Ba) compounds, synthesized by the citrate gel route, have been investigated. These compounds crystallize in an orthorhombic structure (space group Pnma). Semiconducting-like behavior is observed only in Ca-substituted sample while Ba and Sr-substituted samples show metal-insulator type transition. The high and weakly temperature dependent magnetoresistance at low temperature, thermal irreversibility in field-cooled and zero-field-cooled magnetization, and nonsaturating magnetization behavior are expected in systems with electronic phase separation. The cationic size disorder by varying alkaline earth ions causes the electronic phase separation.
Surface anisotropy of permalloy in NM∕NiFe∕NM multilayers
Authors: Rantschler James O. , Chen P. J. , Arrott A. S. , McMichael R. D. , Egelhoff W. F. , Maranville B. B.
Published: May 2005

We measure surface anisotropy in permalloy (Py) deposited between two layers of normal metal (NM=Ag, Cu, or Ta) by measuring the total perpendicular anisotropy with the angular dependence of the ferromagnetic resonance (FMR) field in a resonant cavity. Comparisons are made with the frequency dependence of a broadband FMR technique and vibrating sample magnetometry, and neither match the sensitivity and range of the cavity technique. We see there is a difference between the surface anisotropy at the interfaces: Py–Ta has a surface anisotropy of (0.078±0.009)mJ∕m2 and the Py–Ag and Py–Cu interfaces have surface anisotropies of (0.10±0.007)mJ∕m2.
Composition control of manganite perovskites in metalorganic chemical vapor deposition with in situ spectroscopic monitoring
Authors: Nakamura Toshihiro , Tai Ryusuke , Nishimura Takuro , Tachibana Kunihide
Published: May 2005

Using in situ infrared absorption spectroscopy, the behavior of the film precursors, tris(dipivaloylmethanato)lanthanum [La(DPM)3], tris(dipivaloylmethanato)manganese [Mn(DPM)3], and bis(dipivaloylmethanato)strontium [Sr(DPM)2], in the gas phase was investigated under actual chemical vapor deposition conditions of manganite perovskites. The temperature dependence of the infrared absorption indicates that La(DPM)3, Mn(DPM)3, and Sr(DPM)2 differ significantly in the decomposition temperature. The atomic composition of the deposited film can be controlled on the basis of the precursor densities obtained by the in situ spectroscopic measurements. The composition control based on the in situ monitoring technique is expected to improve the reproducibility of the magnetic property of the deposited film.
Structure and properties of NiFe∕NiFeO magnetic superlattice
Authors: Vas’ko V. A. , Kief M. T.
Published: May 2005

Using a sequence of the sputtering deposition and the natural oxidation at low oxygen partial pressure, a thin (total thickness of 533–900Å) superlattice was produced consisting of NiFe18 and (NiFe18)O layers on Si, Si∕SiO2, and GaAs substrates. The thickness of the as-deposited NiFe layers was in the range 9–533Å. It was found that the thickness of the NiFe film oxidizing as a result of the natural oxidation is limited to 10Å and produces about 16Å of the resulting NiFeO. It was determined that resistivity, saturation magnetization, magnetic anisotropy, and permeability could be controlled in the wide range of values by changing the thickness of the NiFe layers of the NiFe∕NiFeO superlattice. Resistivity could be increased by up to two orders of magnitude and the Hk value could be increased by up to four times with respect to those of the NiFe18 film of a comparable thickness. Stress measurements were performed in a wide range of temperature to characterize the coefficient of thermal expansion and the biaxial modulus of the superlattice. Both values were found to be essentially identical to those of NiFe18 alloy. Thermal stability of the transport and magnetic properties of the NiFe∕NiFeO superlattice with respect to 225°C magnetic annealing was also determined.
Magnetization reversal in patterned double-vortex structures
Authors: Buchanan K. S. , Guslienko K. Yu. , Choe S.-B. , Doran A. , Scholl A. , Bader S. D. , Novosad V.
Published: May 2005

The magnetization reversal process for micron and submicron disk-shaped dots is controlled by successive nucleation, displacement, and annihilation of a magnetic vortex. Here the reversal process for a system involving two ferromagnetic disks separated by a nonmagnetic spacer is investigated experimentally, analytically, and numerically. Permalloy (Ni80Fe20 or Py) dots with thicknesses of up to 40nm and diameters of 0.5–2.5μm separated by a copper spacer (1–45nm thick) were considered. Micromagnetic simulations indicate that the disks will each support oppositely directed vortices at remanence and also show the hysteresis of the coupled structures. The calculations are compared to hysteresis loops and x-ray photoemission electron microscopy images of Py∕Cu∕Py dots produced by electron-beam lithography and magnetron sputtering.
Highly (001)-oriented Ni-doped L1 FePt films and their magnetic properties
Authors: Yan M. L. , Xu Y. F. , Li X. Z. , Sellmyer D. J.
Published: May 2005

We report on Ni-doped nonepitaxial L10 FePt thin films with strong (001) texture. The influences of Ni doping on L10 ordering, orientation, and the magnetic properties of the FePt films have been investigated. In-plane and out-of-plane x-ray diffractions (XRD) were used to analyze the texture of FeNiPt films. For [Fe(0.38nm)∕Ni(0.04nm)∕Pt(0.4)]13 sample, the out-of-plane XRD data showed only (00l) peaks and in-plane data showed (hk0) peaks after annealing, indicating high (001) texture of the FeNiPt films. In comparison with FePt, the (00l) peak positions shifted to higher angle, indicating partial Ni substitution in the L10 lattice. The coercivity, measured at room temperature, decreased as a function of Ni doping. For the film with a Ni layer thickness of 0.06nm, the coercivity is about 6kOe after annealing, which is suitable for the writing performance of high-anisotropy perpendicular recording media.
Magnetic behavior of Sm-Co-based permanent magnets during order/disorder phase transformations
Authors: Aich S. , Kostogorova J. , Shield J. E.
Published: May 2005

The structural transformation from the metastable disordered TbCu7-type SmCo7 structure to the equilibrium ordered Th2Zn17-type Sm2Co17 structure was revealed by x-ray diffraction analysis using Reitveld refinement. The magnetic properties depended strongly on the stage of the transformation, as the coercivity strongly depended on the annealing temperature. The as-solidified alloy in the TbCu7-type structure had a coercivity of 4 kOe, which increased to greater than 9 kOe. The coercivity decreased to around 5 kOe as the transformation neared completion upon annealing at higher temperatures. The magnetization processes were also strongly influenced by the structural state. Initially it was totally controlled by nucleation followed by the domain wall pinning-controlled magnetization process.
Antiferromagnetic exchange-bias in epitaxial ferromagnetic La0.67Sr0.33MnO3∕SrRuO3 bilayers
Authors: Ke X. , Belenky L. J. , Eom C. B. , Rzchowski M. S.
Published: May 2005

Through detailed measurements of the exchange-bias behavior, we have demonstrated that an antiferromagnetic interfacial exchange coupling exists in epitaxial bilayers of the two ferromagnets La0.67Sr0.33MnO3 and SrRuO3. The bilayers were grown on SrTiO3 substrates by pulsed laser deposition with atomic layer control. By field cooling, or by applying a low-temperature pinning field, the bilayers exhibit exchange bias, with the magnetization loops shifted from zero field by the exchange field HE. In the case of field cooling, we find that both the magnitude and sign of exchange field depend on cooling field, consistent with antiferromagnetic interfacial exchange. The coercivity is maximum near the cooling fields that produce zero exchange field.
Strain relaxation and oxygen superstructure modulation in epitaxial Sr4Fe6O13±δ films
Authors: Santiso J. , Pardo J. A. , Solís C. , Garcia G. , Figueras A. , Rossell M. D. , Van Tendeloo G.
Published: May 2005

The compressive strain induced in epitaxial Sr4Fe6O13±δ (SFO) films of different thicknesses grown on SrTiO3 substrates is partially released by the modulation of the incommensurate oxygen superstructure along the a-axis parallel to the substrate [q=αam*, superspace group Xmmm(α00)0s0]. The modulation α value varies proportionally to the in-plane a-parameter in a continuous range from 0.41, for fully strained thin films of about 20–30nm, to 0.44 for partially-relaxed thicker films of about 280nm. This mechanism is responsible for the observed slow relaxation of the cell structure upon the film thickness increase in comparison with an equilibrium misfit dislocation-mediated relaxation.
Periodically oscillating plasma sphere
Authors: Park J. , Nebel R. A. , Stange S. , Murali S. Krupakar
Published: May 2005

The periodically oscillating plasma sphere, or POPS, is a novel fusion concept first proposed by D. C. Barnes and R. A. Nebel [Fusion Technol. 38, 28 (1998)]. POPS utilizes the self-similar collapse of an oscillating ion cloud in a spherical harmonic oscillator potential well formed by electron injection. Once the ions have been phase-locked, their coherent motion simultaneously produces very high densities and temperatures during the collapse phase of the oscillation. A requirement for POPS is that the electron injection produces a stable harmonic oscillator potential. This has been demonstrated in a gridded inertial electrostatic confinement device and verified by particle simulation. Also, the POPS oscillation has been confirmed experimentally through observation that the ions in the potential well exhibit resonance behavior when driven at the POPS frequency. Excellent agreement between the observed POPS frequencies and the theoretical predictions has been observed for a wide range of potential well depths and three different ion species. Practical applications of POPS require large plasma compressions. These large compressions have been observed in particle simulations, although space charge neutralization remains a major issue.
Mechanically induced excess enthalpy in inorganic glasses
Authors: Martin Birgit , Wondraczek Lothar , Deubener Joachim , Yue Yuanzheng
Published: May 2005

We show the effect of mechanical quenching on the thermodynamic state of an inorganic glass, i.e., calcium metaphosphate glass, measured using differential scanning calorimetry (DSC). The calcium metaphosphate glasses were isothermally stretched at a given stress; and then cooled slowly. Afterwards the glasses are subject to two runs of DSC scans. We observed a pronounced sub-Tg exotherm on the first up scan, which is due to the release of the mechanically induced excess enthalpy. The exotherm increases with increasing tensile stress.
Coupling properties of imidazole dimer radical cation assisted by embedded water molecule: Toward understanding of interaction character of hydrogen-bonded histidine residue side-chains
Authors: Yan Shihai , Bu Yuxiang
Published: May 2005

Geometry optimizations are performed at the DFT∕B3LYP∕6-311+G* level. Four intriguing coupling modes, totally eight stable structures are found in the potential energy surfaces of the water-assisted coupling of imidazole dimer radical cation. In these isomers, the water molecules are embedded between two imidazole moieties, and the oxygen atom is tridentate or quadridentate, respectively. The distinct redshifts of the vibrational frequencies of the O–H…N and N–H…O type H bonds indicate the strong interaction of two imidazole rings of respective isomer. Inspection of the highest occupied molecular orbital predicts the alterations of the geometry structures on oxidation and reduction. The low barrier of the fragment rotation demonstrates that the isomerization processes by experiencing the distinct transition states are easy to fulfill, especially for those with O–H…N and C–H…O H bonds. Both the energy difference of the 0°-cis and 180°-trans orientation and the barriers of the fragment rotation are lowered by the water assisting. The range of the zero point vibrational energy correction indicates that the influence on the complexes with N–H…O and O–H…N H bonds (0.13–0.17kcal∕mol) is more significant than those with O–H…N and C–H…O H bonds (±0.03kcal∕mol). The dissociation energies of these isomers indicate that the charges transfer easily through water in the dissociation process and then are distributed mainly over the imidazole ring connecting with water molecule. The isomer with proton transfer between imidazole fragments is the most stable one.
Second-order quasilinear theory of cosmic ray transport
Authors: Shalchi A.
Published: May 2005

The problem of pitch-angle diffusion close to 90° is well known in cosmic ray astrophysics. If the pitch-angle Fokker–Planck coefficient for pure slab geometry is calculated, the quasilinear approximation results in vanishing pitch-angle scattering. For a realistic wave spectrum with a steep dissipation range this vanishing coefficient generates an infinitely large parallel mean free path. It is well known from numerical simulations that the 90° problem is a problem of quasilinear theory and not a problem of reality. In the current paper quasilinear theory is used to calculate corrections of the unperturbed orbit. These corrections can be resubstituted into transport theory to calculate a second-order pitch-angle Fokker–Planck coefficient. The second-order quasilinear theory is an applicable theory which agrees with simulations for pitch-angle diffusion.
Theoretical analysis of vertical colloidal deposition
Authors: Diao J. J. , Hutchison J. B. , Luo Guanghong , Reeves M. E.
Published: May 2005

We have modeled the dynamics of a relatively new deposition technique, vertical colloidal deposition (VCD), for preparing nanoparticle thin films. In this process, the substrate is placed vertically in a nanoparticle suspension and is gradually exposed by evaporation or other slow solvent removal. During the film’s formation, we observe that the colloidal particles are deposited only at the solid-liquid-gas interface. In contrast with the horizontal geometry, treated elsewhere, where the meniscus is pinned, we observe qualitatively different deposition behaviors. In particular, uniform films rather than rings or lines are produced. Thus, we are led to model a diffusion-driven rather than a convection-driven film growth kinetics, and we are able to predict, consistent with our experimental observations, that the film’s areal density is inversely proportional to the descent speed of the suspension surface. Additionally, we find that for submonolayer films, the areal density is proportional to the square of the suspension concentration, converting to a linear dependence once monolayer coverage is attained.
Quenched disorder in a liquid-crystal biosensor: Adsorbed nanoparticles at confining walls
Authors: Guzmán O. , Abbott N. L. , de Pablo J. J.
Published: May 2005

We analyze the response of a nematic liquid-crystal film, confined between parallel walls, to the presence of nanoscopic particles adsorbed at the walls. This is done for a variety of patterns of adsorption (random and periodic) and operational conditions of the system that can be controlled in experimental liquid-crystal-based devices. We compute simulated optical textures and the total optical output of the sensor between crossed polars, as well as the correlation function for the liquid-crystal tensor order parameter; we use these observables to discuss the gradual destruction of the original uniform orientation. For large concentrations of particles adsorbed in random patterns, the liquid crystal at the center of the sensor adopts a multidomain state, characterized by a small correlation length of the tensor order parameter, and also by a loss of optical anisotropy under observation through crossed polars. In contrast, for particles adsorbed in periodic patterns, the nematic at the center of the cell can remain in a monodomain orientation state, provided the patterns in opposite walls are synchronized.
Photochemistry of water: The (H2O)5 cluster
Authors: Sobolewski Andrzej L. , Domcke Wolfgang
Published: May 2005

The structures of the cyclic water pentamer, the H3O+(H2O)3OH− zwitterion, and the H3O(H2O)3OH biradical form of the (H2O)5 cluster have been determined with the second-order Møller–Plesset method and with density-functional theory (DFT). The vertical singlet excitation energies of these structures have been calculated with the second-order approximated coupled-cluster method and with time-dependent DFT, respectively. The molecular and electronic structures of the H3O(H2O)3OH biradical have been characterized for the first time. The lowest electronic states of the biradical are slightly lower in energy than the vertically excited states of the covalent and zwitterionic (H2O)5 clusters and therefore are photochemically accessible from the latter. The electronic absorption spectrum of the biradical exhibits the characteristic features of the absorption spectrum of the hydrated electron. It is argued that the basic mechanisms of the photochemistry of water, in particular the generation of the hydrated electron by UV photons, can be unraveled by relatively straightforward electronic structure and dynamics calculations for finite-size water clusters.