Evaluation of persistent-mode operation in a superconducting MgB2 coil in solid nitrogen

We report the fabrication of a magnesium diboride (MgB2) coil and evaluate its persistent-mode operation in a system cooled by a cryocooler with solid nitrogen (SN2) as a cooling medium. The main purpose of SN2 was to increase enthalpy of the cold mass. For this work, an in situ processed carbon-doped MgB2 wire was used. The coil was wound on a stainless steel former in a single layer (22 turns), with an inner diameter of 109 mm and height of 20 mm without any insulation. The two ends of the coil were then joined to make a persistent-current switch to obtain the persistent-current mode. After a heat treatment, the whole coil was installed in the SN2 chamber. During operation, the resultant total circuit resistance was estimated to be \u3c7.4x10−14 Ω at 19.5 K±1.5 K, which meets the technical requirement for magnetic resonance imaging application

Real-World Six- and Twelve-Month Drug Retention, Remission, and Response Rates of Secukinumab in 2,017 Patients With Psoriatic Arthritis in Thirteen European Countries

Objective There is a lack of real-life studies on interleukin-17 (IL-17) inhibition in psoriatic arthritis (PsA). We assessed real-life 6- and 12-month effectiveness (i.e., retention, remission, low disease activity [LDA], and response rates) of the IL-17 inhibitor secukinumab in PsA patients overall and across 1) number of prior biologic/targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs), 2) years since diagnosis, and 3) European registries. Methods Thirteen quality registries in rheumatology participating in the European Spondyloarthritis Research Collaboration Network provided longitudinal, observational data collected as part of routine care for secondary use. Data were pooled and analyzed with Kaplan-Meier plots, log rank tests, Cox regression, and multiple linear and logistic regression analyses. Results A total of 2,017 PsA patients started treatment with secukinumab between 2015 and 2018. Overall secukinumab retention rates were 86% and 76% after 6 and 12 months, respectively. Crude (LUNDEX adjusted) 6-month remission/LDA (LDA including remission) rates for the 28-joint Disease Activity Index for Psoriatic Arthritis, the Disease Activity Score in 28 joints using the C-reactive protein level, and the Simplified Disease Activity Index (SDAI) were 13%/46% (11%/39%), 36%/55% (30%/46%), and 13%/56% (11%/47%), and 12-month rates were 11%/46% (7%/31%), 39%/56% (26%/38%), and 16%/62% (10%/41%), respectively. Clinical Disease Activity Index remission/LDA rates were similar to the SDAI rates. Six-month American College of Rheumatology 20%/50%/70% improvement criteria responses were 34%/19%/11% (29%/16%/9%); 12-month rates were 37%/21%/11% (24%/14%/7%). Secukinumab effectiveness was significantly better for b/tsDMARD-naive patients, similar across time since diagnosis (4 years), and varied significantly across the European registries. Conclusion In this large real-world study on secukinumab treatment in PsA, 6- and 12-month effectiveness was comparable to that in previous observational studies of tumor necrosis factor inhibitors. Retention, remission, LDA, and response rates were significantly better for b/tsDMARD-naive patients, were independent of time since diagnosis, and varied significantly across the European countries.Peer reviewe

Ribosome formation from subunits studied by stopped-flow and Rayleigh light scattering

Light scattering and standard stopped-flow techniques were used to monitor rapid association of ribosomal subunits during initiation of eubacterial protein synthesis. The effects of the initiation factors IF1, IF2, IF3 and buffer conditions on subunit association were studied along with the role of GTP in this process. The part of light scattering theory that is essential for kinetic measurements is high-lighted in the main text and a more general treatment of Rayleigh scattering from macromolecules is given in an appendix

Superconducting properties of MgB2 wire using ball milled low purity boron

MgB2/Fe wire samples were prepared by using ball-milled 96% boron (B) powder with strong semi-crystalline phase. We observed samples that contained ball-milled 96% B in comparison with one made from as-supplied commercial 96% B, with the results showing a significant enhancement in the high field transport critical current density (Jct) due to small grain size and better reactivity. However, the inter-grain connectivity became worse, which could lead to poor Jct in low field and an increased level of disorder

Solid cryogen: a cooling system for future MgB2 MRI magnet

An efficient cooling system and the superconducting magnet are essential components of magnetic resonance imaging (MRI) technology. Herein, we report a solid nitrogen (SN2) cooling system as a valuable cryogenic feature, which is targeted for easy usability and stable operation under unreliable power source conditions, in conjunction with a magnesium diboride (MgB 2) superconducting magnet. The rationally designed MgB 2/SN2 cooling system was first considered by conducting a finite element analysis simulation, and then a demonstrator coil was empirically tested under the same conditions. In the SN2 cooling system design, a wide temperature distribution on the SN2 chamber was observed due to the low thermal conductivity of the stainless steel components. To overcome this temperature distribution, a copper flange was introduced to enhance the temperature uniformity of the SN2 chamber. In the coil testing, an operating current as high as 200 A was applied at 28 K (below the critical current) without any operating or thermal issues. This work was performed to further the development of SN2 cooled MgB 2 superconducting coils for MRI applications

Increased superconductivity for CNT doped MgB2 sintered in 5T pulsed magnetic field

The superconductivity of carbon nanotube (CNT) doped MgB2 sintered in pulsed magnetic field (PMF) was investigated with Raman scattering measurements and Raman spectral fit analysis. Although the carbon (C) substitution for the boron (B) is increased for the sample sintered in PMF, its superconductivity is advanced comparing with the sample sintered without PMF. The improved critical transition temperature, Tc, is attributed to the strengthening of the electron-phonon coupling (EPC) in MgB2, as reflected by the broadened E 2g mode in the Raman spectra, because the carbon atoms are homogeneously distributed in the boron planes

Quench protected structured superconducting cable

Quench protected structured (QPS) superconducting cables, methods of fabricating the same, and methods of bending the same are disclosed. The methods of bending the QPS superconducting cables can be employed to produce windings. The QPS superconducting cables can rapidly drive a distributed quench to a normal conducting state in a superconducting cable if a region of the cable spontaneously quenches during high current operation.U

Quench protected structured superconducting cable

Quench protected structured (QPS) superconducting cables, methods of fabricating the same, and methods of bending the same are disclosed. The methods of bending the QPS superconducting cables can be employed to produce windings. The QPS superconducting cables can rapidly drive a distributed quench to a normal conducting state in a superconducting cable if a region of the cable spontaneously quenches during high current operation.U