bluuebunny/crossref_metadata_2025 huggingface dataset:
Eomesodermin induces Mesp1 expression and cardiac differentiation from embryonic stem cells in the absence of Activin
Authors: van den Ameele Jelle , Tiberi Luca , Bondue Antoine , Paulissen Catherine , Herpoel Adèle , Iacovino Michelina , Kyba Michael , Blanpain Cédric , Vanderhaeghen Pierre
Published: March 2012

The transcription factor Eomesodermin (Eomes) is involved in early embryonic patterning, but the range of cell fates that it controls as well as its mechanisms of action remain unclear. Here we show that transient expression of Eomes promotes cardiovascular fate during embryonic stem cell differentiation. Eomes also rapidly induces the expression of Mesp1, a key regulator of cardiovascular differentiation, and directly binds to regulatory sequences of Mesp1. Eomes effects are strikingly modulated by Activin signalling: high levels of Activin inhibit the promotion of cardiac mesoderm by Eomes, while they enhance Eomes‐dependent endodermal specification. These results place Eomes upstream of the Mesp1‐dependent programme of cardiogenesis, and at the intersection of mesodermal and endodermal specification, depending on the levels of Activin/Nodal signalling.
Science in Suzhou: establishment and function of neural circuits
Authors: Scott Kristin , Hammarlund Marc
Published: March 2012

The Cold Spring Harbour Asia conference on ‘Assembly, Plasticity, Dysfunction and Repair of Neural Circuits’ took place in Suzhou, China, in October 2011. Developmental, cell, molecular and systems neuroscientists convened to discuss the establishment, function and plasticity of neural circuits in diverse organisms.
Golgi-SNARE GS28 potentiates cisplatin-induced apoptosis by forming GS28–MDM2–p53 complexes and by preventing the ubiquitination and degradation of p53
Authors: Sun Nian-Kang , Huang Shang-Lang , Chien Kun-Yi , Chao Chuck C.-K.
Published: March 2012

In the present study, we observed that the Golgi-SNARE (soluble N-ethylmaleimide-sensitive fusion protein-attachment protein receptor) GS28 forms a complex with p53 in HEK (human embryonic kidney)-293 cells. Given that p53 represents a tumour suppressor that affects the sensitivity of cancer cells to various chemotherapeutic drugs, we examined whether GS28 may influence the level of sensitivity to the DNA-damaging drug cisplatin. Indeed, knockdown of GS28 using short-hairpin RNA (shGS28) induced resistance to cisplatin in HEK-293 cells. On the other hand, overexpression of GS28 sensitized HEK-293 cells to cisplatin, whereas no sensitization effect was noted for the mitotic spindle-damaging drugs vincristine and taxol. Accordingly, we observed that knockdown of GS28 reduced the accumulation of p53 and its pro-apoptotic target Bax. Conversely, GS28 overexpression induced the accumulation of p53 and Bax as well as the pro-apoptotic phosphorylation of p53 on Ser46. Further experiments showed that these cellular responses could be abrogated by the p53 inhibitor PFT-α (pifithrin-α), indicating that GS28 may affect the stability and activity of p53. The modulatory effects of GS28 on cisplatin sensitivity and p53 stability were absent in lung cancer H1299 cells which are p53-null. As expected, ectopic expression of p53 in H1299 cells restored the modulatory effects of GS28 on sensitivity to cisplatin. In addition, GS28 was found to form a complex with the p53 E3 ligase MDM2 (murine double minute 2) in H1299 cells. Furthermore, the ubiquitination of p53 was reduced by overexpression of GS28 in cells, confirming that GS28 enhances the stability of the p53 protein. Taken together, these results suggest that GS28 may potentiate cells to DNA-damage-induced apoptosis by inhibiting the ubiquitination and degradation of p53.
Insulin-like Growth Factor I and Anthropometric Parameters in a Danish Population
Authors: Friedrich N. , Jørgensen T. , Juul A. , Spielhagen C. , Nauck M. , Wallaschofski H. , Linneberg A.
Published: March 2012

During the last decade several studies indicated that low insulin-like growth factor (IGF) I levels are related to higher risk of cardiovascular disease and mortality. Obesity represents one further main cardiovascular risk factor which might also be related to IGF-I. The objective of the present study was to analyse the associations between anthropometric measures and IGF-I levels in a population-based sample.

From the Danish cross-sectional Health2006 study 3 328 subjects (1 835 women; 1 493 men) aged 19–72 years were included in the analyses. Serum IGF-I levels were determined by an immunoassay. Body height, weight as well as waist and hip circumferences were measured. Body-mass-index, waist-to-hip ratio and waist-to-height ratio were calculated.

Circulating IGF-I levels were inversely associated with all anthropometric markers as evaluated by linear regression adjusting for age, alcohol consumption, smoking and physical activity. Our large cross-sectional study suggests that IGF-I may serve as the link between obesity and mortality although any causal relation cannot be inferred and longitudinal analyses are needed to clarify the causal relation.
Zebrafish: A Model for Understanding Diabetic Complications
Authors: Jörgens K. , Hillebrands J.-L. , Hammes H.-P. , Kroll J.
Published: March 2012

Diabetes mellitus causes several vascular complications in patients, such as macrovascular problems including myocardial infarction, peripheral artery diseases and stroke and microvascular problems including nephropathy and retinopathy. Likewise, diabetes mellitus is associated with other complications such as neuropathy and delayed wound healing. The zebrafish has been used for decades as a model organism for studies in developmental biology. In fact several common and important developmental mechanisms have been identified in zebrafish which are similar in mammals. The zebrafish has short generation intervals and zebrafish embryos are transparent and therefore provide unique imaging opportunities. In combination with genetic manipulations, including gene silencing protocols by using morpholinos, mutant or transgenic fish lines, the zebrafish has become one of the most important models in developmental biology. Over and above, zebrafish is also an established model organism for several pathophysiological conditions which are related to human diseases. For instance, zebrafish is used as an inflammation and regeneration model because of its ability to partially compensate for organ loss (e. g., heart and fins). It is also used for drug screening, in tumor biology, for systems biology, congenital and hereditary disease, and in infection 1.
Glucose Effects on the Peritoneum: What Can We Learn from Rodent Models?
Authors: Müller-Krebs S. , Zhang W. , Kihm L. , Reiser J. , Nawroth P. , Schwenger V.
Published: March 2012

During long-term peritoneal dialysis (PD) the peritoneal membrane underlies processes of structural and functional reorganization mediated by high glucose and reactive glucose metabolites that are contained in PD solutions; this process is accompanied by increasing fibrosis. Mechanistically, the peritoneal damage is triggered by the interaction of advanced glycation end-products with their receptor; this is true for rodents as well as for humans. With this knowledge interventional strategies can be tested in rodent models, among them are the lipid soluble vitamin B1 analogue benfotiamine (BF) or detoxifying enzymes such as glyoxalase. Of additional interest is the finding that PD fluids do not only cause local but also systemic damage, in particular renal and cardiovascular. In the case of kidney damage, the intervention with BF was also successful. Taken together, PD can be regarded as a local model for long-term diabetes together with systemic aspects of damage.
Yeast as a Model to Understand Mechanisms and Consequences of Protein Modifications by Metabolism Derived Toxic Products
Authors: Tyedmers J.
Published: March 2012

An inevitable consequence of metabolism in cells across all kingdoms of life is the non-enzymatic formation of toxic metabolites such as reactive oxygen species (ROS) and reducing sugars, whose reaction products are associated with several diseases such as clinical complications of diabetes, cataracts, cancer and age-related late-onset diseases like Parkinson’s Disease and Alzheimer’s Disease, amongst others. Yeast has been used successfully to study the reaction of these toxic metabolites with proteins in vivo, which I will summarize with exemplified studies on 2 crucial reactions, protein carbonylation and protein glycation.
Effect of surfactant molecular weight on particle morphology of SmCo5 prepared by high energy ball milling
Authors: Crouse C. A. , Michel E. , Shen Y. , Knutson S. J. , Hardenstein B. K. , Spowart J. E. , Leontsev S. O. , Semiatin S. L. , Horwath J. , Turgut Z. , Lucas M. S.
Published: March 2012

Surfactant-assisted high energy ball milling (HEBM) is a widely used technique for producing nanostructured magnetic materials with oleic acid (OA) being the most commonly utilized surfactant reported in literature to date. No conclusive explanation has been presented for the wide use of OA and only a few studies have deviated from its use. OA has a boiling point of 360 °C which presents issues for complete removal of the surfactant after the HEBM process. Exposing the nanostructured materials to the high temperatures required for surfactant removal is known to result in grain growth and oxidation. In other studies, select surfactant systems, such as octanoic acid or oleylamine, have been used, however, a systematic study examining the dependence of surfactant selection on overall particle (flake) morphology has yet to be performed. In this study, we have qualitatively and quantitatively examined the effects of surfactant selection on the morphology and magnetic properties of SmCo5 utilizing surfactants with lower boiling points that are structurally similar to OA. Our results demonstrate that there was little change in the morphological and magnetic properties for the different surfactants. The implication is that lower boiling point surfactants may be used for HEBM, which require less severe conditions for surfactant removal after milling thereby preserving the integrity of the powders.
Properties of hydrogenation-disproportionation-desorption-recombination NdFeB powders prepared from recycled sintered magnets
Authors: Périgo E. A. , da Silva S. C. , Martin R. V. , Takiishi H. , Landgraf F. J. G.
Published: March 2012

The effects of the hydrogenation-disproportionation-desorption-recombination (HDDR) processing conditions on the microstructure and magnetic properties of NdFeB powders prepared from recycling sintered N42 grade magnets were evaluated. Temperatures below 840 oC and above 900 oC are deleterious to HDDR powders’ properties. The hydrogen pressure, ranging from 60 to 135 kPa, has a major influence on the remanence compared to that on the intrinsic coercivity. The best magnetic properties (Jr = 0.58 T and μ0Hc = 1.15 T) were obtained with Trecomb = 860 °C, PH2 = 135 kPa, and trecomb = 330 s. Such coercivity value corresponds to 93% of the starting material, not achieved yet by optimizing the HDDR process and without using Dy.
Granular L1 FePt-B and FePt-B-Ag (001) thin films for heat assisted magnetic recording
Authors: Granz Steven D. , Barmak Katayun , Kryder Mark H.
Published: March 2012

A comparison was made of FePt-B and FePt-B-Ag thin films having different volume contents of boron, which were RF sputtered with in-situ heating at 425–575 °C onto Si substrates with 20 nm thick (002) MgO. By introducing boron into FePt and varying the sputtering conditions, films with grain sizes ranging from 2.5 to 10 nm were produced. The boron promoted columnar growth, but made ordering more difficult. However, by adding Ag into FePt-B, ordering improved while coercivity increased from 7 to 11 kOe with no significant impact on the microstructure. We obtained films with grain sizes down to 2.5 nm with center-to-center spacing of 3.1 nm. The reduced grain size, columnar microstructure and increase in ordering and coercivity by adding Ag into the FePt-B thin films are favorable for application in heat assisted magnetic recording.
Small epitaxial graphene devices for magnetosensing applications
Authors: Panchal V. , Cedergren K. , Yakimova R. , Tzalenchuk A. , Kubatkin S. , Kazakova O.
Published: March 2012

Hall sensors with the width range from 0.5 to 20.0 μm have been fabricated out of a monolayer graphene epitaxially grown on SiC. The sensors have been studied at room temperature using transport and noise spectrum measurements. The minimum detectable field of a typical 10-μm graphene sensor is ≈2.5 μT/√Hz, making them comparable with state of the art semiconductor devices of the same size and carrier concentration and superior to devices made of CVD graphene. Relatively high resistance significantly restricts performance of the smallest 500-nm devices. Carrier mobility is strongly size dependent, signifying importance of both intrinsic and extrinsic factors in the optimization of the device performance.
Development of magnetostrictive inkjet head for liquid droplet formation
Authors: Yoo Jae-Hyun , Park Young-Woo
Published: March 2012

This paper presents the development of Magnetostrictive inkjet head (MAG-Jet), which consists of a Terfenol-D actuator, a chamber connected to a fluid reservoir through a fluid inlet, and a glass nozzle. The functional requirement for the MAG-Jet is that the droplet must exit the nozzle at a speed of 5 m/s. The diameters of the chamber and nozzle are set to 1.0 mm and 100 μm, respectively. To achieve the functional requirement of the initial settings, a fluid dynamic model is developed for estimating the required force per unit area exerted by the Terfenol-D actuator. Then, a mathematical model of the magnetic circuit for the actuator is developed in terms of magnetic flux and reluctance, and this is followed by a finite element analysis using a commercial program. The developed MAG-Jet is used to evaluate the performance. The input current of all the experiments is set as ± 1.8 A and the bipolar waveform is selected as the basic driving waveform. Also, the optimal process is ensured to determine the time values for the driving waveform. The designed driving waveform applied to the MAG-Jet has the inflow time of 370 μs, ejection time of 10 μs, holding time of 360 μs, and breakup time of 10 μs. Successful droplet formation is made by using the developed MAG-Jet.
Large-scale synthesis of high moment FeCo nanoparticles using modified polyol synthesis
Authors: Zamanpour Mehdi , Chen Yajie , Hu Bolin , Carroll Kyler , Huba Zachary J. , Carpenter E. E. , Lewis Laura H. , Harris Vincent. G.
Published: March 2012

Binary alloys of Fe and Co have among the highest magnetizations of any transition metal alloy systems, but their affinity to form oxides act to reduce the magnetization of nanoparticles as their size is reduced below ∼30 nm. Here, we demonstrate the synthesis of single phase, size-controlled FeCo nanoparticles having magnetization greater than 200 emu/g via a non-aqueous method in which ethylene glycol served as solvent and reducing agent as well as surfactant. Experiments indicated pure-phase FeCo nanoparticles, having saturation magnetization up to 221 emu/g for sizes of 20–30 nm, in single batch processes resulting in > 2 g/batch. Post-synthesis oxidation of nanoparticles was investigated until very stable nanoparticles were realized with constant magnetization over time.
Structure and magnetism of BaTi1-xFexO3-δ multiferroics
Authors: Dang N. V. , Nguyen Ha M. , Chuang Pei-Yu , Zhang Jie-Hao , Thanh T. D. , Hu Chih-Wei , Chen Tsan-Yao , Yang Hung-Duen , Lam V. D. , Lee Chih-Hao , Hong L. V.
Published: March 2012

The effect of Fe dopant content, x, on the magnetism of polycrystalline BaTi1-xFexO3-δ (BTFO) multiferroic samples was investigated using magnetization measurements in correlation with the crystallographic and local structures. The changes of coercivity and magnetization as functions of x are closely related to the variation of oxygen vacancy content, δ, which can be deduced from the Fe oxidation number estimation using Fe K-edge x-ray absorption spectroscopy. It is shown that although the samples exhibit ferromagnetic (FM) hysteresis at room temperature, a dominant paramagnetic phase coexisting with the FM phase makes it difficult to identify the FM contribution to the total magnetization. Spin-glass and/or superparamagnetic behavior may be ruled out due to the fact that both zero-field-cooled and field-cooled thermomagnetization curves almost totally overlap together over the whole range of measured temperatures.
The effect of Fe/Al ratio on the thermal stability and magnetocaloric effect of Gd55FexAl45-x (x = 15–35) glassy ribbons
Authors: Yuan Fang , Li Qian , Shen Baolong
Published: March 2012

The effect of Fe/Al ratio on the thermal properties, magnetocaloric effect, and refrigeration capacity (RC) of Gd55FexAl45−x (x = 15–35) glassy ribbons has been investigated. With Fe/Al ratio increasing, the maximum magnetic entropy changes (−ΔSm) are located in the range of 2.92 to 5.01 J · kg−1 · K−1, and the temperature at the peak values of −ΔSm (Tp), the Curie temperature (Tc), as well as the full width at half maximum of the −ΔSm (δTFWHM), all increase gradually. The maximum RC of 868 J kg−1 has been obtained for x = 20, which makes the Gd55FexAl45−x (x = 15–35) glassy ribbons attractive candidates for magnetic refrigeration materials. Furthermore, the glass transition phenomenon tends to disappear with as the Fe/Al ratio increases; this could be attributed to the formation of some crystallites.
Characterization of L1-FePt/Fe based exchange coupled composite bit pattern media
Authors: Wang Hao , Li Weimin , Rahman M. Tofizur , Zhao Haibao , Ding Jun , Chen Yunjie , Wang Jian-Ping
Published: March 2012

L10-FePt exchange coupled composite (ECC) bit patterned media has been considered as a potential candidate to achieve high thermal stability and writability for future high density magnetic recording. In this paper, FePt based ECC bit patterned structures with 31 nm bit size and 37 nm pitch size were fabricated using di-block copolymer lithography on 3 inch wafer. Remanant states were tracked using magnetic force microscopy (MFM). DC demagnetization (DCD) curves were plotted by counting the reversed bits in the MFM images. Magnetic domains in which the magnetizations of the neighboring bits were aligned to the same direction were observed in the MFM patterns. Thermal decay measurement was performed for the samples to obtain the thermal stability and gain factor. The thermal barrier was found around 210 kBT with a gain factor up to 1.57 for the bit patterned structure FePt(4 nm)/Fe(4 nm).
Effect of oxygen off-stoichiometry on magnetic and magneto-transport properties of nanocrystalline under-doped LCMO
Authors: Bitla Yugandhar , Kaul S. N.
Published: March 2012

Magnetic and magneto-transport investigation of nanocrystalline under-doped manganite La0.875Ca0.125MnO3+δ with δ = 0.0 (sample x1) and δ = 0.06 (sample x2) reveals that the dipolar interactions are primarily responsible for establishing ferromagnetic order in the insulating state and that the uniaxial magnetic anisotropy is stronger in x2. The reduction of magnetization and resistivity in x2 compared to that in x1 is brought about by the oxygen off-stoichiometry as it increases the concentration of Mn4+ ions. Bringing the crystallite size down to nanometer range induces an insulating-to-metal transition and a re-entrant insulating (ferromagnetic) phase at temperatures T < 30 K.
Interface magnetism of iron grown on sulfur and hydrogen passivated GaAs(001)
Authors: Kardasz B. , Watkins S. P. , Montoya E. A. , Burrowes C. , Girt E. , Heinrich B.
Published: March 2012

Sulfur (S) and hydrogen (H) atom passivated GaAs(001) templates were used for deposition of ultrathin crystalline Fe films using molecular beam epitaxy, where the Fe thickness ranged from 10 to 45 atomic layers. Reflection high-energy electron diffraction patterns showed that the S- and H-passivated surfaces had no and very weak (1 × 2) superlattice reconstructions, respectively. This indicates that these GaAs(001) templates have a square-like symmetry. Magnetic anisotropies were investigated using the in-plane angular dependence of ferromagnetic resonance at 36 GHz. The in-plane cubic and uniaxial anisotropies and perpendicular uniaxial field were described by bulk and interface contributions, indicating that the Fe films have a high lattice coherence. The magnetic properties of the Fe films were compared to those grown on more commonly used GaAs(001) templates having a (4 × 6) reconstruction with an As-rich in-plane uniaxial symmetry. The Fe films grown on S-passivated templates exhibited unique magnetic properties caused by a decreased lattice spacing compared to the bulk Fe.
Observation of anomalous Hall effect in Cu-Py-crossed structure with in-plane magnetization
Authors: Chen D. C. , Yao Y. D. , Chiu Y. C. , Lee S. F.
Published: March 2012

We investigate a series of Cu-Py-crossed stripe devices in which the contact magnetoresistance behavior exhibits hysteretic loops originating from anomalous Hall effect in Py at the Cu/Py contact area with in-plane magnetization. These highly reproducible hysteretic loops relate directly to the magnetization switching of Py wires at the crossed regions. The nonzero magnitude of resistance difference (ΔR) between the two remnant states at zero Oe depends on the width of Cu by a roughly reciprocal relation, but is independent of that of Py wire. The ΔR ranges between 0.1 ∼ 0.6 mΩ with Cu width of 100 nm ∼ 500 nm and Cu/Py thickness of (65 nm)/(31 nm) ∼ (50 nm)/(20 nm). The results provide understanding of how the Hall voltage is induced and sensed.
Robust switching of swirls for coupled ferromagnetic nanobricks with the Landau structure
Authors: Arrott A. S.
Published: March 2012

Two magnetic configurations, found by micromagnetic calculations, for a pair of magnetostatically coupled iron nanobricks lower the energy barrier for switching the positions of the swirls on their surfaces using gradient magnetic fields from currents through or near the nanobricks. The advantageous properties of the pairs of nanobricks can be engineered by varying the gap between the vertically stacked pair.
Temperature dependent magnetic structure of lithium delithiated LixFeSO4F (x = 0, 1) by Mössbauer spectroscopy
Authors: Lee In Kyu , Wook Hyun Sung , Kouh Taejoon , Shim In-Bo , Sung Kim Chul
Published: March 2012

Recently, lithium iron sulfate compounds have been highly considered for a positive electrode material for lithium ion batteries. In this work, LiFeSO4F and the fully delithiated FeSO4F were prepared by the ionothermal process and chemical oxidation reaction method. The LixFeSO4F (x = 0, 1) samples show the triclinic structure with P-1 space group. In the case of delithiated FeSO4F, changes in lattice parameters were observed due to the disappearance of the Li site while maintaining the triclinic structure. Temperature-dependent magnetic susceptibility curves show the antiferromagnetic (AFM) structure with the ordering temperature of 28 K for LiFeSO4F and 99 K for FeSO4F. Also, temperature-dependent Mössbauer spectra of LiFeSO4F below TN were fitted with two-sets of eight Lorentzian indicating the existence of two different types of Fe2+ ions due to the different hyperfine and electric quadrupole interactions. With the lithium delithiated, the Fe3+ iron ions in FeSO4F exhibit two-sets of six-line patterns due to the electron transfer in FeO4F2 site by lithium delithiation. These suggest that the different AFM ordering in LixFeSO4F can be originated from the Fe2+/Fe3+ magnetic ions with different charge distributions and spin contributions.
Crossing point phenomena (T* = 2.7 K) in specific heat curves of superconducting ferromagnets RuSr2Gd1.4Ce0.6Cu2O10-δ
Authors: Kumar Anuj , Tandon R. P. , Wang Jianli , Zeng Rong , Awana V. P. S.
Published: March 2012

Crossing point phenomena are one of the interesting and still puzzling effects in strongly correlated electron systems. We have synthesized RuSr2Gd1.4Ce0.6Cu2O10-δ (GdRu-1222) magneto-superconductor through the standard solid state reaction route and measured its magnetic, transport, and thermal properties. We also synthesized RuSr2Eu1.4Ce0.6Cu2O10-δ (EuRu-1222) then measured its heat capacity in zero magnetic fields for reference. The studied compounds crystallized in the tetragonal structure with space group I4/mmm. To explore the crossing point phenomena, the specific heat [Cp (T)] was investigated in the temperature range 1.9-250 K, under magnetic field of up to 70 kOe. Unfortunately though no magnetic and superconducting transitions are observed in specific heat, a Schottky-type anomaly is observed at low temperatures below 20 K. This low temperature Schottky-type anomaly can be attributed to splitting of the ground state spectroscopic term 8S7/2 of paramagnetic Gd3 + ions by both internal and external magnetic fields. It was also observed that Cp (T) is measured for different values of magnetic field, possesses the same crossing point (T* = 2.7 K), up to the applied magnetic field 70 kOe. A quantitative explanation of this phenomenon, based on its shape and temperature dependence of the associated generalized heat capacity (Cp), is presented.
Geometric dependence of static and kinetic pinning of domain walls on ferromagnetic nanowires
Authors: Ahn Sung–Min , Moon Kyoung-Woong , Kim Dong-Hyun , Choe Sug–Bong
Published: March 2012

We investigate two distinct pinning mechanisms—denoted as static and kinetic pinning of magnetic domain wall (DW) in Permalloy nanowires with different widths. Both pinning situations are realized at an artificial notch on U-shaped Permalloy nanowires, depending on the initial DW states, moving or pinned. We find experimentally that the kinetic and static depinning fields simultaneously increase as the width of the nanowire decreases, whereas a difference between static and kinetic depinning fields monotomically decreases. This is ascribed to the shape anisotropy field of the DWs depending on the geometry of nanowires based on one-dimensional collective model.
Magnetism and transport properties of epitaxial Fe–Ga thin films on GaAs(001)
Authors: Anh Tuan Duong , Duc Dung Dang , Thanh Son Vo , Shin Yooleemi , Cho Sunglae
Published: March 2012

Epitaxial Fe–Ga thin films in disordered bcc α-Fe crystal structure (A2) have been grown on GaAs(001) by molecular beam epitaxy. The saturated magnetization (MS) decreased from 1371 to 1105 kA/m with increasing Ga concentration from 10.5 to 24.3 % at room temperature. The lattice parameter increased with the increase in Ga content because of the larger atomic radius of Ga atom than that of Fe. The increase in carrier density with Ga content caused in lower resistivity.
Improved thrust calculations of active magnetic bearings considering fringing flux
Authors: Jang Seok-Myeong , Kim Kwan-Ho , Ko Kyoung-Jin , Choi Ji-Hwan , Sung So-Young , Lee Yong-Bok
Published: March 2012

A methodology for deriving fringing permeance in axisymmetric devices such as active thrust magnetic bearings (ATMBs) is presented. The methodology is used to develop an improved equivalent magnetic circuit (EMC) for ATMBs, which considers the fringing effect. This EMC was used to characterize the force between the housing and mover and the dependence of thrust and inductance on the air gap and input current, respectively. These characteristics were validated by comparison with those obtained by the finite element method and in experiments.
Design of a 270ps-access 7-transistor/2-magnetic-tunnel-junction cell circuit for a high-speed-search nonvolatile ternary content-addressable memory
Authors: Matsunaga Shoun , Katsumata Akira , Natsui Masanori , Endoh Tetsuo , Ohno Hideo , Hanyu Takahiro
Published: March 2012

A novel 7-transistor/2-magnetic-tunnel-junction (7 T-2MTJ) cell circuit is proposed for a high-speed and compact nonvolatile ternary content-addressable memory (TCAM). Since critical path for switching in the TCAM cell circuit, which determines the performance of the TCAM, is only a single MOS transistor, switching delay of the TCAM word circuit is minimized. As a result, 270 ps of switching delay in 144-bit TCAM word circuit is achieved under a 90 nm CMOS/MTJ technology with magneto-resistance ratio of 100%, which is about two times faster than a conventional CMOS-based TCAM.
Clocking magnetic field-coupled devices by domain walls
Authors: Csaba György , Kiermaier Josef , Becherer Markus , Breitkreutz Stephan , Ju Xueming , Lugli Paolo , Schmitt-Landsiedel Doris , Porod Wolfgang
Published: March 2012

We study the interaction between propagating domain walls in permalloy nanowires and nanomagnetic dots made of Co/Pt multilayers. The magnetic behavior of dots placed above/below the domain wall conductor is strongly influenced by the field of the wall. Using micromagnetic simulations we show that the field generated by the domain wall can switch the coupled dots to their magnetically ordered ground state. This effect can be exploited for clocking magnetic field-coupled devices and possibly substitute electrical clocking structures.
High temperature magnetic properties of Co1-xMgxFe2O4 nanoparticles prepared by forced hydrolysis method
Authors: Franco A. , e Silva F. C. , Zapf Vivien S.
Published: March 2012

In this work, we study the effect of Mg2+ nonmagnetic ions on the magnetic properties of cubic Co1-xMgxFe2O4 mixed nanostructured ferrites synthesized by a forced hydrolysis method. Magnetization measurements show that all specimens are superparamagnetic at room temperature, and the saturation magnetization (Ms) decreases with increasing the molar magnesium concentration, being 260 emu/cm3 and 160 emu/cm3 for x = 0.0 and 0.6, respectively. The Curie temperature TC, ∼740 K is determined by means of the inverse of the susceptibility versus temperature and slightly depends on the Mg content. The effective anisotropy constant, (Keff) decreases with substitution of Co2+ ion by nonmagnetic Mg2+ ions in the spinel structure. These results are discussed in terms of interparticle interactions induced by the thermal fluctuations, cation distribution and other imperfections that could increase with temperature.
Nonlinearly generated harmonic signals in ultra-small waveguides with magnetic films: Tunable enhancements of 2nd and 4th harmonics
Authors: Marsh J. , Zagorodnii V. , Celinski Z. , Camley R. E.
Published: March 2012

The nonlinear generation of high harmonic signals (up to 5th harmonic) is explored in an ultra-small waveguide which contains a thin ferromagnetic film. The strength of the different harmonics is highly tunable. In particular, the power in the 2nd and 4th harmonic signals may be enhanced by over two orders of magnitude by varying the direction of a static magnetic field with respect to the long axis of the waveguide. In contrast, the 3rd and 5th harmonics are relatively insensitive to the direction of the magnetic field. The experimental results are explained by analytical and numerical calculations.
Benchmarking the performance of time-dependent density functional methods
Authors: Leang Sarom S. , Zahariev Federico , Gordon Mark S.
Published: March 2012

The performance of 24 density functionals, including 14 meta-generalized gradient approximation (mGGA) functionals, is assessed for the calculation of vertical excitation energies against an experimental benchmark set comprising 14 small- to medium-sized compounds with 101 total excited states. The experimental benchmark set consists of singlet, triplet, valence, and Rydberg excited states. The global-hybrid (GH) version of the Perdew-Burke-Ernzerhoff GGA density functional (PBE0) is found to offer the best overall performance with a mean absolute error (MAE) of 0.28 eV. The GH-mGGA Minnesota 2006 density functional with 54% Hartree-Fock exchange (M06-2X) gives a lower MAE of 0.26 eV, but this functional encounters some convergence problems in the ground state. The local density approximation functional consisting of the Slater exchange and Volk-Wilk-Nusair correlation functional (SVWN) outperformed all non-GH GGAs tested. The best pure density functional performance is obtained with the local version of the Minnesota 2006 mGGA density functional (M06-L) with an MAE of 0.41 eV.
Free energy partitioning analysis of the driving forces that determine ion density profiles near the water liquid-vapor interface
Authors: Arslanargin Ayse , Beck Thomas L.
Published: March 2012

Free energy partitioning analysis is employed to explore the driving forces for ions interacting with the water liquid-vapor interface using recently optimized point charge models for the ions and SPC/E water. The Na+ and I− ions are examined as an example kosmotrope/chaotrope pair. The absolute hydration free energy is partitioned into cavity formation, attractive van der Waals, local electrostatic, and far-field electrostatic contributions. We first compute the bulk hydration free energy of the ions, followed by the free energy to insert the ions at the center of a water slab. Shifts of the ion free energies occur in the slab geometry consistent with the SPC/E surface potential of the water liquid-vapor interface. Then the free energy profiles are examined for ion passage from the slab center to the dividing surface. The profiles show that, for the large chaotropic I− ion, the relatively flat total free energy profile results from the near cancellation of several large contributions. The far-field electrostatic part of the free energy, largely due to the water liquid-vapor interface potential, has an important effect on ion distributions near the surface in the classical model. We conclude, however, that the individual forms of the local and far-field electrostatic contributions are expected to be model dependent when comparing classical and quantum results. The substantial attractive cavity free energy contribution for the larger I− ion suggests that there is a hydrophobic component important for chaotropic ion interactions with the interface.
Ferromagnetic resonance study of FeCoMoB microwires during devitrification process
Authors: Klein P. , Varga R. , Infante G. , Vázquez M.
Published: March 2012

Magnetic properties of FeCoMoB glass-coated microwires with high positive magnetostriction have been investigated during the process of devitrification in the temperature range: 0-600 °C by ferromagnetic resonance (FMR) studies. The FeCoMoB microwire shows natural ferromagnetic resonance that reflects a complex anisotropy distribution. FMR spectrum for as cast sample shows up to four resonance maxima when ranging frequency from 10 MHz up to 11.3 GHz. After annealing, the anisotropy distribution becomes more regular and the number of FMR peaks decreases. The anisotropy and stress amplitude has been estimated from the FMR spectra, showing a strong decrease with annealing temperature and being low and constant for the nanocrystalline state. In addition, Gilbert damping decreases with annealing temperature, too. The low Gilbert damping (∼0.01) for the nanocrystalline state makes the nanocrystalline FeCoMoB microwire an ideal material for applications in which fast magnetization processes are required.
Symmetry group analysis of an ideal plastic flow
Authors: Lamothe Vincent
Published: March 2012

In this paper, we study a finite-dimensional Lie point symmetry group of a system describing an ideal plastic plane flow in two dimensions in order to find analytical solutions. The infinitesimal generators that span this Lie algebra are given. We completely classify the subalgebras of codimension up to two into conjugacy classes under the action of the symmetry group. Based on invariant forms, we use Ansätze to compute symmetry reductions in such a way that the obtained solutions simultaneously cover many invariant and partially invariant solutions. We calculate solutions of algebraic, trigonometric, inverse trigonometric and elliptic type. Some solutions depending on one or two arbitrary functions of one variable have also been found. In some cases, the shape of a potentially feasible extrusion die corresponding to the solution is deduced. These tools could be used to thin, curve, undulate or shape a ring in an ideal plastic material.
Forming delocalized intermediate states with realistic quantum dots
Authors: Reid W. M. , Driscoll T. , Doty M. F.
Published: March 2012

Experiments and theoretical models suggest that the performance of intermediate band solar cells based on quantum dots (QDs) will be enhanced by the formation of delocalized intermediate bands. However, reasonable device performance has only been achieved when the QD separation is large and energy states are localized to individual QDs. In this paper we analyze the formation of delocalized bands in a realistic QD material that has inhomogeneously distributed energy levels. We calculate the QD uniformity or barrier thickness necessary to create delocalized states in realistic materials and propose a design to create delocalized states while including strain balancing layers.
Coherent dynamics of meta-toluidine investigated by quasielastic neutron scattering
Authors: Faraone Antonio , Hong Kunlun , Kneller Larry R. , Ohl Michael , Copley John R. D.
Published: March 2012

The coherent dynamics of a typical fragile glass former, meta-toluidine, was investigated at the molecular level using quasielastic neutron scattering, with time-of-flight and neutron spin echo spectrometers. It is well known that the static structure factor of meta-toluidine shows a prepeak originating from clustering of the molecules through hydrogen bonding between the amine groups. The dynamics of meta-toluidine was measured for several values of the wavevector transfer Q, which is equivalent to an inverse length scale, in a range encompassing the prepeak and the structure factor peak. Data were collected in the temperature range corresponding to the liquid and supercooled states, down to the glass transition. At least two dynamical processes were identified. This paper focuses on the slowest relaxation process in the system, the α-relaxation, which was found to scale with the macroscopic shear viscosity at all the investigated Q values. No evidence of “de Gennes” narrowing associated with the prepeak was observed, in contrast with what happens at the Q value corresponding to the interparticle distance. Moreover, using partially deuterated samples, the dynamics of the clusters was found to be correlated to the single-particle dynamics of the meta-toluidine molecules.
Resonances in extreme mass-ratio inspirals: Asymptotic and hyperasymptotic analysis
Authors: Gair Jonathan , Yunes Nicolás , Bender Carl M.
Published: March 2012

An expected source of gravitational waves for future detectors in space is the inspirals of small compact objects into much more massive black holes. These sources have the potential to provide a wealth of information about astronomy and fundamental physics. On short time scales the orbit of the small object is approximately geodesic. Generic geodesics for a Kerr black hole spacetime have a complete set of integrals and can be characterized by three frequencies of the motion. Over the course of an inspiral, a typical system will pass through resonances where two of these frequencies become commensurate. The effect of the resonance will be to alter significantly the rate of inspiral for the duration of the resonance. Understanding the impact of these resonances on gravitational wave phasing is important for the detection of these signals and for the exploitation of the observations for astrophysics and fundamental physics. Two differential equations that might describe the passage of an inspiral through such a resonance are investigated. These differences depending on whether it is the phase or the frequency components of a Fourier expansion of the motion that are taken to be continuous through the resonance. Asymptotic and hyperasymptotic analysis are used to find the late-time analytic behavior of the solution for a system that has passed through a resonance. Linearly growing (weak resonances) or linearly decaying (strong resonances) solutions are found depending on the strength of the resonance. In the weak-resonance case, frequency resonances leave an imprint (a resonant memory) on the gravitational wave frequency evolution. For frequency resonances, the transition between weak and strong resonances is characterized by a square-root-branch-cut singularity. On the strong resonance side of this singularity, solutions starting with different initial conditions bunch up into groups exponentially in the independent variable (time) and we show how this behavior can be understood by considering solutions near the singular point.
DNA-modified silicon nanocrystals studied by X-ray luminescence and X-ray absorption spectroscopies: Observation of a strong infra-red luminescence band
Authors: Coxon P. R. , Newman M. , Hunt M. R. C. , O’Farrell N. , Horrocks B. R. , Poolton N. R. J. , Šiller L.
Published: March 2012

Silicon nanocrystals (SiNCs) modified with 18-mer DNA oligonucleotides have been studied by X-ray excited optical luminescence (XEOL) and X-ray absorption spectroscopy (XAS) in photoluminescence yield (PLY) and total electron yield (TEY) modes. Luminescence spectra from the DNA-modified SiNCs under X-ray excitation display distinct differences from simple alkyl terminated SiNCs. The DNA-modified SiNCs show strong luminescence at 540 ± 10 nm under vacuum ultraviolet excitation which is assigned to nitrogen 1s – σ* transitions within the DNA bases. Under excitation at 130 eV the PLY spectra from the same samples show the native nanocrystal ultraviolet emission band is suppressed, and the strongest emission peak is red shifted from 430 ± 10 nm to 489 ± 10 nm which we attribute to base nitrogen 1s transitions. In addition, a strong emission band in the infrared region at 815 ± 10 nm is observed. This clearly resolved strong IR band from the DNA-modified SiNCs may provide a useful luminescence signature in cell-labeling techniques and open up a range of applications for invivo assays.
Magnetic field-induced spin-crossover transition in [MnIII(taa)] studied by x-ray absorption spectroscopy
Authors: Long Her Jim , Matsuda Yasuhiro H. , Nakano Motohiro , Niwa Yasuhiro , Inada Yasuhiro
Published: March 2012

X-ray absorption near-edge structure (XANES) spectra of Mn in a spin-crossover compound, [MnIII(taa)], was studied in pulsed high magnetic fields up to 37 T. The significant changes in the XANES spectra, related to the spin-crossover from the low-spin (LS) state to high-spin (HS) state, were found to be induced by magnetic fields at temperatures down to 17 K. The fraction of the field-induced HS states was, at most, 30%, and the magnetic field dependence of the HS fraction exhibited hysteresis. The observed field-induced spin-crossover at T = 17 K (T/Tc ∼ 0.4, where Tc (= 46 K) is the spin-crossover transition temperature) cannot be understood as the field-induced macroscopic phase transition, because the transition magnetic field is known to be higher than 55 T at low temperatures. The observed field-induced LS-HS transition is likely the local microscopic transition at the single-molecule level.
Resolutions of the Coulomb operator. VI. Computation of auxiliary integrals
Authors: Limpanuparb Taweetham , Hollett Joshua W. , Gill Peter M. W.
Published: March 2012

We discuss the efficient computation of the auxiliary integrals that arise when resolutions of two-electron operators (specifically, the Coulomb operator [T. Limpanuparb, A. T. B. Gilbert, and P. M. W. Gill, J. Chem. Theory Comput. 7, 830 (2011)10.1021/ct200115t] and the long-range Ewald operator [T. Limpanuparb and P. M. W. Gill, J. Chem. Theory Comput. 7, 2353 (2011)10.1021/ct200305n]) are employed in quantum chemical calculations. We derive a recurrence relation that facilitates the generation of auxiliary integrals for Gaussian basis functions of arbitrary angular momentum and propose a near-optimal algorithm for its use.
Polarization insensitive in-fiber mode-locker based on carbon nanotube with N-methyl-2-pryrrolidone solvent filled fiber microchamber
Authors: Mou Chengbo , Rozhin Aleksey G. , Arif Raz , Zhou Kaiming , Turitsyn Sergei
Published: March 2012

We report an in-fiber laser mode locker based on carbon nanotube with n-methyl-2-pryrrolidone solvent filled in-fiber microchamber. Symmetrically femtosecond laser fabricated in-fiber microchamber with randomly oriented nanotubes assures polarization insensitive oscillation of laser mode locking. The proposed and demonstrated passively mode locked fiber laser shows higher energy soliton output. The laser has an output power of ∼29 mW (corresponding to 11 nJ energy). It shows stable soliton output with a repetition rate of ∼2.3 MHz and pulse width of ∼3.37 ps.
Effects of Li content on the phase structure and electrical properties of lead-free (Ag0.85−xLixNa0.1K0.05)NbO3 piezoelectric ceramics
Authors: Wu Lang , Liu Naiming , Zhou Fei , Teng Yuancheng , Li Yuxiang
Published: March 2012

Lead-free ceramics (Ag0.85−xLixNa0.1K0.05)NbO3 (ALNKN−x, x = 0−0.16) doped with 0.5 mol. % CuO were prepared by solid state reaction method under air atmosphere. The effects of Li content on the phase structure and electrical properties of the ALNKN−x ceramics were investigated. A morphotropic phase boundary (MPB) between orthorhombic and rhombohedral phases is found at x ≈ 0.08−0.14. Both the ferroelectric–ferroelectric phase transition temperature (TFE) and Curie temperature (TC) shift toward higher temperatures with increasing x. Only the phase transition peak near the TC is observed when x ≥ 0.12. The ferroelectric phase of the ALNKN−x ceramics becomes more stable with increasing x. Furthermore, the ceramics with x = 0.12 exhibit relatively good electrical properties along with a high Curie temperature (d33 = 44 pC/N, kp = 17.7%, Pr = 14.5 µC/cm2, Ec = 37.2 kV/cm, and Tc = 335 °C). The results provide helpful guidance to develop new lead-free piezoelectric materials with good temperature stability.
High temperature phase transitions and critical exponents of Samarium orthoferrite determined by in situ optical ellipsometry
Authors: Berini B. , Fouchet A. , Popova E. , Scola J. , Dumont Y. , Franco N. , da Silva R. M. C. , Keller N.
Published: March 2012

Determining phase transitions has always been a great challenge in material science due to their important fundamental and technological aspects. Recently, iron-based perovskites (RFeO3), exhibiting phase transitions at high temperatures, have attracted much interest for their functional properties at room temperature, such as multiferroicity (BiFeO3) and ultrafast spin dynamics (TmFeO3). In this family of materials, Samarium orthoferrite (SmFeO3) is a weak ferromagnet, ordering at high temperatures and exhibiting an intrinsic spin reorientation transition above room temperature, which is “hidden” in macroscopic magnetization measurements in polycrystalline samples. In the present article, we show that the related magnetic high temperature phase transitions can be studied through their dielectric functions by spectroscopic ellipsometry in situ and without any need for an applied external magnetic field. The presence of this intrinsic spin reorientation transition is demonstrated for textured SmFeO3 films and we have determined a critical exponent of β = 0.45 ± 0.01 for the magnetic phase transition, coherently from optical, magneto-optical, and structural investigations.
Ray congruences that generate conformal foliations
Authors: Baird Paul , Wehbe Mohammad
Published: March 2012

Given a Riemannian 3-manifold (M3, g0) endowed with a unit vector field U0 that is tangent to a conformal foliation, we require that the pair extend to a space-time \documentclass[12pt]{minimal}\begin{document}$({\mathcal M}, {\mathcal G})$\end{document}(M,G) endowed with a space-like unit vector field Ut in such a way that Ut simultaneously generates null geodesics and is tangent to a conformal foliation on space-like slices t = constant. The property that the foliation be conformal is intimately related to CR-geometry.