Ultra-fast vortex motion in a direct-write Nb-C superconductor.

The ultra-fast dynamics of superconducting vortices harbors rich physics generic to nonequilibrium collective systems. The phenomenon of flux-flow instability (FFI), however, prevents its exploration and sets practical limits for the use of vortices in various applications. To suppress the FFI, a superconductor should exhibit a rarely achieved combination of properties: weak volume pinning, close-to-depairing critical current, and fast heat removal from heated electrons. Here, we demonstrate experimentally ultra-fast vortex motion at velocities of 10-15 km s-1 in a directly written Nb-C superconductor with a close-to-perfect edge barrier. The spatial evolution of the FFI is described using the edge-controlled FFI model, implying a chain of FFI nucleation points along the sample edge and their development into self-organized Josephson-like junctions (vortex rivers). In addition, our results offer insights into the applicability of widely used FFI models and suggest Nb-C to be a good candidate material for fast single-photon detectors.

Microwave emission from superconducting vortices in Mo/Si superlattices.

Most of superconductors in a magnetic field are penetrated by a lattice of quantized flux vortices. In the presence of a transport current causing the vortices to cross sample edges, emission of electromagnetic waves is expected due to the continuity of tangential components of the fields at the surface. Yet, such a radiation has not been observed so far due to low radiated power levels and lacking coherence in the vortex motion. Here, we clearly evidence the emission of electromagnetic waves from vortices crossing the layers of a superconductor/insulator Mo/Si superlattice. The emission spectra consist of narrow harmonically related peaks which can be finely tuned in the GHz range by the dc bias current and, coarsely, by the in-plane magnetic field value. Our findings show that superconductor/insulator superlattices can act as dc-tunable microwave generators bridging the frequency gap between conventional radiofrequency oscillators and (sub-)terahertz generators relying upon the Josephson effect.

Alloy multilayers and ternary nanostructures by direct-write approach.

The fabrication of nanopatterned multilayers, as used in optical and magnetic applications, is usually achieved by two independent steps, which consist in the preparation of multilayer films and in the successive patterning by means of lithography and etching processes. Here we show that multilayer nanostructures can be fabricated by using focused electron beam induced deposition (FEBID), which allows the direct writing of nanostructures of any desired shape with nanoscale resolution. In particular, [Formula: see text] multilayers are prepared by the alternating deposition from the metal carbonyl precursors, [Formula: see text] and [Formula: see text], and neopentasilane, [Formula: see text]. The ability to fabricate nanopatterned multilayers by FEBID is of interest for the realization of hyperbolic metamaterials and related nanodevices. In a second experiment, we treated the multilayers by low-energy electron irradiation in order to induce atomic species intermixing with the purpose to obtain ternary nanostructured compounds. Transmission electron microscopy and electrical transport measurements indicate that in thick multilayers, (n = 12), the intermixing is only partial, taking place mainly in the upper part of the structures. However, for thin multilayers, (n = 2), the intermixing is such that a transformation into the L21 phase of the Co2FeSi Heusler compound takes place over the whole sample volume.

Laboratory Setup for Scanning-Free Grazing Emission X-ray Fluorescence.

Grazing incidence and grazing emission X-ray fluorescence spectroscopy (GI/GE-XRF) are techniques that enable nondestructive, quantitative analysis of elemental depth profiles with a resolution in the nanometer regime. A laboratory setup for soft X-ray GEXRF measurements is presented. Reasonable measurement times could be achieved by combining a highly brilliant laser produced plasma (LPP) source with a scanning-free GEXRF setup, providing a large solid angle of detection. The detector, a pnCCD, was operated in a single photon counting mode in order to utilize its energy dispersive properties. GEXRF profiles of the Ni-Lα,ß line of a nickel-carbon multilayer sample, which displays a lateral (bi)layer thickness gradient, were recorded at several positions. Simulations of theoretical profiles predicted a prominent intensity minimum at grazing emission angles between 5° and 12°, depending strongly on the bilayer thickness of the sample. This information was used to retrieve the bilayer thickness gradient. The results are in good agreement with values obtained by X-ray reflectometry, conventional X-ray fluorescence and transmission electron microscopy measurements and serve as proof-of-principle for the realized GEXRF setup. The presented work demonstrates the potential of nanometer resolved elemental depth profiling in the soft X-ray range with a laboratory source, opening, for example, the possibility of in-line or even in situ process control in semiconductor industry.

Simultaneous atomic-resolution electron ptychography and Z-contrast imaging of light and heavy elements in complex nanostructures.

The aberration-corrected scanning transmission electron microscope (STEM) has emerged as a key tool for atomic resolution characterization of materials, allowing the use of imaging modes such as Z-contrast and spectroscopic mapping. The STEM has not been regarded as optimal for the phase-contrast imaging necessary for efficient imaging of light materials. Here, recent developments in fast electron detectors and data processing capability is shown to enable electron ptychography, to extend the capability of the STEM by allowing quantitative phase images to be formed simultaneously with incoherent signals. We demonstrate this capability as a practical tool for imaging complex structures containing light and heavy elements, and use it to solve the structure of a beam-sensitive carbon nanostructure. The contrast of the phase image contrast is maximized through the post-acquisition correction of lens aberrations. The compensation of defocus aberrations is also used for the measurement of three-dimensional sample information through post-acquisition optical sectioning.

A liquid jet setup for x-ray scattering experiments on complex liquids at free-electron laser sources.

In this paper we describe a setup for x-ray scattering experiments on complex fluids using a liquid jet. The setup supports Small and Wide Angle X-ray Scattering (SAXS/WAXS) geometries. The jet is formed by a gas-dynamic virtual nozzle (GDVN) allowing for diameters ranging between 1 µm and 20 µm at a jet length of several hundred µm. To control jet properties such as jet length, diameter, or flow rate, the instrument is equipped with several diagnostic tools. Three microscopes are installed to quantify jet dimensions and stability in situ. The setup has been used at several beamlines performing both SAXS and WAXS experiments. As a typical example we show an experiment on a colloidal dispersion in a liquid jet at the X-ray Correlation Spectroscopy instrument at the Linac Coherent Light Source free-electron laser.

dc and ac magnetic properties of thin-walled Nb cylinders with and without a row of antidots.

dc and ac magnetic properties of two thin-walled superconducting Nb cylinders with a rectangular cross-section are reported. Magnetization curves and the ac response were studied on as-prepared and patterned samples in magnetic fields parallel to the cylinder axis. A row of micron-sized antidots (holes) was made in the film along the cylinder axis. Avalanche-like jumps of the magnetization are observed for both samples at low temperatures for magnetic fields not only above H c1, but in fields lower than H c1 in the vortex-free region. The positions of the jumps are not reproducible and they change from one experiment to another, resembling vortex lattice instabilities usually observed for magnetic fields larger than H c1. At temperatures above [Formula: see text] and [Formula: see text] the magnetization curves become smooth for the patterned and the as-prepared samples, respectively. The magnetization curve of a reference planar Nb film in the parallel field geometry does not exhibit jumps in the entire range of accessible temperatures. The ac response was measured in constant and swept dc magnetic field modes. Experiment shows that ac losses at low magnetic fields in a swept field mode are smaller for the patterned sample. For both samples the shapes of the field dependences of losses and the amplitude of the third harmonic are the same in constant and swept field near H c3. This similarity does not exist at low fields in a swept mode.

[Preclinical and clinical management after mass disaster : Experiences from the train collision in Bad Aibling on 9 February 2016]. / Präklinisches und klinisches Management nach Massenunfall : Erfahrungen aus dem Zugunglück Bad Aibling am 9.2.2016.

Mass casualty incidents (MCI) in this day and age represent a special challenge, which initially require on-site coordination and logistics and then a professional distribution of victims (triage) to surrounding hospitals. Technical, logistical and even specialist errors can impair this flow of events. It therefore seems advisable to make a detailed analysis of every MCI. In this article the railway incident from 9 February 2016 is analyzed taking the preclinical and clinical cirumstances into consideration and conclusions for future management are drawn. As a special entity it could be determined that fixed table units in passenger trains represent a particularly dangerous hazard and in many instances in this analysis led to characteristic abdominal and thoracic injuries.

Evaluation of treatment response to enzyme replacement therapy with Velaglucerase alfa in patients with Gaucher disease using whole-body magnetic resonance imaging.

OBJECTIVE: This was a retrospective data analysis to evaluate the treatment response to enzyme replacement therapy (ERT) with Velaglucerase alfa using whole-body magnetic resonance imaging (MRI). MATERIALS AND METHODS: A baseline and follow-up MRI were performed on 18 Gaucher Type 1 patients at an interval of 11.6 months. The MRI score systems determined the Bone-Marrow-Burden (BMB) score, the Düsseldorf-Gaucher score (DGS), and the Vertebra-Disc-Ratio (VDR). The Severity Score Index Type 1 (GD-DS3) was also assessed. RESULTS: The baseline MRI medians were: BMB, 7.00; DGS, 3.00; and VDR: 1.70; while, the follow-up MRI medians were: BMB, 7.00; DGS, 3.00; and VDR: 1.73. The baseline GD-DS3 median was 2.40 (BMB excl.: 0.50) and the follow-up median was 2.00 (BMB excl.: 0.50). There was weak statistical significance with the Wilcoxon signed-rank test for the DGS (p=0.034) and GD-DS3 (p=0.047) between both MRIs. CONCLUSION: Velaglucerase alfa therapy is a effective long-term treatment for Gaucher Type 1 patients who are newly diagnosed or switching therapies. Measurements with whole-body MRI and an objective scoring system were reliable tools for detecting early stage bone marrow activity. Further research is needed to evaluate the "Booster-Effect" of Velaglucerase alfa therapy in Gaucher skeletal disease.

Radiation dose reduction in postoperative computed position control of cochlear implant electrodes in lambs - An experimental study.

OBJECTIVE: Cochlear implants (CI) are standard treatment for prelingually deafened children and postlingually deafened adults. Computed tomography (CT) is the standard method for postoperative imaging of the electrode position. CT scans accurately reflect electrode depth and position, which is essential prior to use. However, routine CT examinations expose patients to radiation, which is especially problematic in children. We examined whether new CT protocols could reduce radiation doses while preserving diagnostic accuracy. METHODS: To investigate whether electrode position can be assessed by low-dose CT protocols, a cadaveric lamb model was used because the inner ear morphology is similar to humans. The scans were performed at various volumetric CT dose-indexes CTDIvol)/kV combinations. For each constant CTDIvol the tube voltage was varied (i.e., 80, 100, 120 and 140kV). This procedure was repeated at different CTDIvol values (21mGy, 11mGy, 5.5mGy, 2.8mGy and 1.8mGy). To keep the CTDIvol constant at different tube voltages, the tube current values were adjusted. Independent evaluations of the images were performed by two experienced and blinded neuroradiologists. The criteria diagnostic usefulness, image quality and artifacts (scaled 1-4) were assessed in 14 cochlear-implanted cadaveric lamb heads with variable tube voltages. RESULTS: Results showed that the standard CT dose could be substantially reduced without sacrificing diagnostic accuracy of electrode position. The assessment of the CI electrode position was feasible in almost all cases up to a CTDIvol of 2-3mGy. The number of artifacts did not increase for images within this dose range as compared to higher dosages. The extent of the artifacts caused by the implanted metal-containing CI electrode does not depend on the radiation dose and is not perceptibly influenced by changes in the tube voltage. Summarizing the evaluation of the CI electrode position is possible even at a very low radiation dose. CONCLUSIONS: CT imaging of the temporal bone for postoperative electrode position control of the CI is possible with a very low and significantly radiation dose. The tube current-time product and voltage can be reduced by 50% without increasing artifacts. Low-dose postoperative CT scans are sufficient for localizing the CI electrode.

Direct writing of CoFe alloy nanostructures by focused electron beam induced deposition from a heteronuclear precursor.

Recently, focused electron beam-induced deposition has been employed to prepare functional magnetic nanostructures with potential in nanomagnetic logic and sensing applications by using homonuclear precursor gases like Fe(CO)5 or Co2(CO)8. Here we show that an extension towards the fabrication of bi-metallic compounds is possible by using a single-source heteronuclear precursor gas. We have grown CoFe alloy magnetic nanostructures from the HFeCo3(CO)12 metal carbonyl precursor. The compositional analysis indicates that the samples contain about 80 at% of metal and 10 at% of carbon and oxygen. Four-probe magnetotransport measurements are carried out on nanowires of various sizes down to a width of 50 nm, for which a room temperature resistivity of 43 µΩcm is found. Micro-Hall magnetometry reveals that 50 nm × 250 nm nanobars of the material are ferromagnetic up to the highest measured temperature of 250 K. Finally, the transmission electron microscopy (TEM) microstructural investigation shows that the deposits consist of a bcc Co-Fe phase mixed with a FeCo2 O4 spinel oxide phase with nanograins of about 5 nm diameter.

Evaluation of Bone Marrow Infiltration in Non-Neuropathic Gaucher Disease Patients with Use of Whole-Body MRI--A Retrospective Data Analysis.

PURPOSE: To evaluate whole-body magnetic resonance imaging (WB-MRI) for the assessment of bone marrow infiltration in patients with confirmed Gaucher disease type 1 under long-term enzyme replacement therapy (ERT). MATERIALS AND METHODS: This retrospective data analysis included 38 patients in two subgroups. Group A: 10 females, 9 males, 15-29 years, mean age 22 years and Group B: 11 females, 8 males, 29-77 years, mean age 49 years, all treated with alglucerase or imiglucerase for at least 12.5 years. Whole-body MRI was carried out in all patients using a standard MRI protocol. Two radiologists assessed all MR images retrospectively with the use of three different MRI score systems: The bone marrow burden (BMB) score, the Düsseldorf-Gaucher score (DGS) and the vertebra disc ratio (VDR). As a clinical component, severity score index type 1 (GD-DS3) was determined. RESULTS: In both groups the MR scores showed low to moderate pathologic levels but no statistically significant difference was found between both groups. The median scores in group A/group B were 7.00/9.00 for the BMB score (p=0.07), 4.00/3.00 for the DGS score (p=0.062) and 1.54/1.62 for the VDR score (p=0.267). The GD-DS3 score was statistically significantly different between both groups (1.6/3.9, p=0.000) and osseous Gaucher disease complications were only found in group B. CONCLUSION: Bone marrow involvement and typical clinical manifestations are reduced to a minimum, when ERT starts immediately after the confirmed diagnosis of Gaucher disease type 1. The applied MR scores are useful markers to control bone marrow infiltration under enzyme replacement therapy in older patients. Pathologic MR scores in young patients may reflect postponed fat conversion of the juvenile bone marrow. This issue has to be examined in further studies. KEY POINTS: Whole-body MRI is valuable for the staging of Gaucher disease type 1. Osseous complications are reduced to a minimum in early treated patients. MR score systems have to be adjusted in young Gaucher patients.

Post-growth purification of Co nanostructures prepared by focused electron beam induced deposition.

In the majority of cases nanostructures prepared by focused electron beam induced deposition (FEBID) employing an organometallic precursor contain predominantly carbon-based ligand dissociation products. This is unfortunate with regard to using this high-resolution direct-write approach for the preparation of nanostructures for various fields, such as mesoscopic physics, micromagnetism, electronic correlations, spin-dependent transport and numerous applications. Here we present an in situ cleaning approach to obtain pure Co-FEBID nanostructures. The purification procedure lies in the exposure of heated samples to a H2 atmosphere in conjunction with the irradiation by low-energy electrons. The key finding is that the combination of annealing at 300 °C, H2 exposure and electron irradiation leads to compact, carbon- and oxygen free Co layers down to a thickness of about 20 nm starting from as-deposited Co-FEBID structures. In addition to this, in temperature-dependent electrical resistance measurements on post-processed samples we find a typical metallic behavior. In low-temperature magnetoresistance and Hall effect measurements we observe ferromagnetic behavior.

Magnetoresistance of granular Pt-C nanostructures close to the metal-insulator transition.

We investigate the electrical and magneto-transport properties of Pt-C granular metals prepared by focused electron beam induced deposition. In particular, we consider samples close to the metal-insulator transition obtained from as-grown deposits by means of a low-energy electron irradiation treatment. The temperature dependence of the conductivity shows a σ ∼lnT behavior, with a transition to σ ∼ √T at low temperature, as expected for systems in the strong coupling tunneling regime. The magnetoresistance is positive and is described within the wavefunction shrinkage model, normally used for disordered systems in the weak coupling regime. In order to fit the experimental data, spin-dependent tunneling has to be taken into account. In the discussion we attribute the origin of the spin-dependency to the confinement effects of Pt nano-grains embedded in the carbon matrix.

Synthesis of nanowires via helium and neon focused ion beam induced deposition with the gas field ion microscope.

The ion beam induced nanoscale synthesis of platinum nanowires using the trimethyl (methylcyclopentadienyl)platinum(IV) (MeCpPt(IV)Me3) precursor is investigated using helium and neon ion beams in the gas field ion microscope. The He(+) beam induced deposition resembles material deposited by electron beam induced deposition with very small platinum nanocrystallites suspended in a carbonaceous matrix. The He(+) deposited material composition was estimated to be 16% Pt in a matrix of amorphous carbon with a large room-temperature resistivity (∼3.5 × 10(4)-2.2 × 10(5) µΩ cm) and temperature-dependent transport behavior consistent with a granular material in the weak intergrain tunnel coupling regime. The Ne(+) deposited material has comparable composition (17%), however a much lower room-temperature resistivity (∼600-3.0 × 10(3) µΩ cm) and temperature-dependent electrical behavior representative of strong intergrain coupling. The Ne(+) deposited nanostructure has larger platinum nanoparticles and is rationalized via Monte Carlo ion-solid simulations which show that the neon energy density deposited during growth is much larger due to the smaller ion range and is dominated by nuclear stopping relative to helium which has a larger range and is dominated by electronic stopping.

Rumination, gender, and depressive symptoms associated with caregiving strain in bipolar disorder.

OBJECTIVE: To evaluate the associations between indices of caregiving strain, ruminative style, depressive symptoms, and gender among family members of patients with bipolar disorder. METHOD: One hundred and fifty primary caregivers of patients enrolled in the Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD) participated in a cross-sectional study to evaluate the role of ruminative style in maintaining depressive symptoms associated with caregiving strain. Patient lifetime diagnosis and current episode status were evaluated by the Affective Disorder Evaluation and the Clinical Monitoring Form. Caregivers were evaluated within 30 days of the patient on measures of family strain, depressive symptoms, and ruminative style. RESULTS: Men and women did not differ on depression, caregiver strain, or ruminative style scores. Scores suggest an overall mild level of depression and moderate caregiver strain for the sample. Greater caregiver strain was significantly associated (P<0.05) with rumination and level of depressive symptoms, controlling for patient clinical status and demographic variables. Rumination reduced the apparent association between strain and depression by nearly half. Gender was not significantly associated with depression or rumination. CONCLUSION: Rumination helps explain depressive symptoms experienced by both male and female caregivers of patients with bipolar disorder. Interventions for caregivers targeted at decreasing rumination should be considered.

Room temperature L10 phase transformation in binary CoPt nanostructures prepared by focused-electron-beam-induced deposition.

CoPt-C binary alloys have been fabricated by focused-electron-beam-induced deposition by the simultaneous use of Co2(CO)8 and (CH3)3CH3C5H4Pt as precursor gases. The alloys are made of CoPt nanoparticles embedded in a carbonaceous matrix. TEM investigations show that as-grown samples are in an amorphous phase. By means of a room temperature low-energy electron irradiation treatment the CoPt nanoparticles transform into face-centered tetragonal L10 nanocrystallites. In parallel, the system undergoes a transition from a superparamagnetic to a ferromagnetic state at room temperature. By variation of the post-growth irradiation dose the electrical and magneto-transport properties of the alloy can be continuously tuned.