Effect of nano-particle doping on the upper critical field and flux pinning in MgB2

The effect of nano particle doping on the critical current density of MgB2 is reviewed. Most nano-particle doping leads to improvement of Jc(H) performance while some shows a negative effect as with Cu and Ag. Nano-carbon containing dopants have two distinguishable contributions to the enhancement of Jc field performance: increase of upper critical field and improvement of flux pinning. Among all the dopants studied so far, nano SiC doping showed the most significant and reproducible enhancement in Jc(H). The nano SiC doping introduced many precipitates at a scale below 10 nm, which serve as strong pinning centers. Jc for the nano SiC doped samples increased by more than an order of magnitude at high fields and all temperatures compared to the undoped samples. The significant enhancement in Jc(H) of nano-SiC doping has been widely verified and confirmed, having a great potential for applications. An attempt is made to clarify the controversy on the effects of nano Fe and Ti doping on Jc

Transport critical current density in Fe-sheathed nano-SiC doped MgB2 wires

The nano-SiC doped MgB2/Fe wires were fabricated using a powder-in-tube method and an in-situ reaction process. The depression of Tc with increasing SiC doping level remained rather small due to the counterbalanced effect of Si and C co-doping. The high level SiC co-doping allowed creation of the intra-grain defects and nano-inclusions, which act as effective pinning centers, resulting in a substantial enhancement in the Jc(H) performance. The transport Jc for all the wires is comparable to the magnetic Jc at higher fields despite the low density of the samples and percolative nature of current. The transport Ic for the 10wt% SiC doped MgB2/Fe reached 660A at 5K and 4.5T (Jc = 133,000A/cm2) and 540A at 20K and 2T (Jc = 108,000A/cm2). The transport Jc for the 10wt% SiC doped MgB2 wire is more than an order of magnitude higher than for the state-the-art Fe-sheathed MgB2 wire reported to date at 5K and 10T and 20K and 5T respectively. There is a plenty of room for further improvement in Jc as the density of the current samples is only 50%.Comment: 4 pages, 7 figures, presented at ASC 2002, Housto

Transport critical current density in Fe-sheathed nano-SiC doped MgB/sub 2/ wires

The nano-SiC doped MgB/sub 2//Fe wires were fabricated using a powder-in-tube method and an in-situ reaction process. The depression of T/sub c/ with increasing SiC doping level remained rather small due to the counterbalanced effect of Si and C co-doping. The high level SiC co-doping allowed creation of the intra-grain defects and nano-inclusions, which act as effective pinning centers, resulting in a substantial enhancement in the J/sub c/(H) performance. The transport J/sub c/ for all the wires is comparable to the magnetic J/sub c/ at higher fields despite the low density of the samples and percolative nature of current. The transport I/sub c/ for the 10wt% SiC doped MgB/sub 2//Fe reached 660A at 5K and 4.5T (J/sub c/=133000A/cm/sup 2/) and 540A at 20K and 2T (J/sub c/=108000A/cm/sup 2/). The transport J/sub c/ for the 10wt% SiC doped MgB/sub 2/ wire is more than an order of magnitude higher than for the state-the-art Fe-sheathed MgB/sub 2/ wire reported to date at 5K and 10T and 20K and 5T respectively. There is a plenty of room for further improvement in J/sub c/ as the density of the current samples is only 50%

Intelligent Knee Sleeves: A Real-time Multimodal Dataset for 3D Lower Body Motion Estimation Using Smart Textile

The kinematics of human movements and locomotion are closely linked to the activation and contractions of muscles. To investigate this, we present a multimodal dataset with benchmarks collected using a novel pair of Intelligent Knee Sleeves (Texavie MarsWear Knee Sleeves) for human pose estimation. Our system utilizes synchronized datasets that comprise time-series data from the Knee Sleeves and the corresponding ground truth labels from the visualized motion capture camera system. We employ these to generate 3D human models solely based on the wearable data of individuals performing different activities. We demonstrate the effectiveness of this camera-free system and machine learning algorithms in the assessment of various movements and exercises, including extension to unseen exercises and individuals. The results show an average error of 7.21 degrees across all eight lower body joints when compared to the ground truth, indicating the effectiveness and reliability of the Knee Sleeve system for the prediction of different lower body joints beyond the knees. The results enable human pose estimation in a seamless manner without being limited by visual occlusion or the field of view of cameras. Our results show the potential of multimodal wearable sensing in a variety of applications from home fitness to sports, healthcare, and physical rehabilitation focusing on pose and movement estimation.Comment: Accepted by Thirty-seventh Conference on Neural Information Processing Systems (Neurips) D&B Trac

Association of MGLL Intronic C>T Single Nucleotide Polymorphism (rs782440) with Borderline Personality Disorder: A Case-Control Study

Objective: From the perspective of etiology, borderline personality disorder (BPD) is a multifactorial and complexdisorder, hence our understanding about the molecular basis and signaling of this disorder is extremely limited.The purpose of this study was evaluating the relationship between BPD and the Monoacylglycerol lipase (MGLL)polymorphism rs782440 in the population of Hamadan, Iran.Materials and Methods: In this case-control study, 106 participants including 53 patients with BPD and 53healthy control subjects were selected by psychiatrists in the Department of Psychiatry at Farshchian SinaHospital in Hamadan. The BPD patients were selected based on the Diagnostic and Statistical Manual of MentalDisorders (DSM-5) form for diagnosing BPD patients. For genotyping, polymerase chain reaction (PCR) wasused to amplify the desired region including the MGLL intronic C>T single nucleotide polymorphism (SNP)(rs782440) and afterward the amplicon was sequenced using the Sanger sequencing method. To determine thegenotype of these patients, their sequences were aligned with the reference sequence of MGLL through the CLCgenomic workbench software.Results: The results indicated that the frequency of TT in comparison to the CC genotype was significantly different(P=0.003) and the risk of BPD in change from the TT genotype to CC genotype was increased by 6.679%. Regardingthe frequency of allele in this group, no significant difference was observed.Conclusion: This paper, has studied and reports for the first time, the association between MGLL SNP (rs782440) withBPD. The findings of the current research revealed that the TT genotype increases the risk of BPD compared to the CCgenotype. Considering the lack of a suitable diagnostic biomarker for BPD, using this potential biomarker in the nearfuture can be promising

Development of superconducting magnesium diboride conductors

The work in this thesis concentrates on the fabrication and characterization of MgB2 superconducting bulk wire and tape. An overview of the research on MgB2 superconductor during the last three years is also provided. High transport and magnetic critical current density values above 105 A/cm2 have been obtained for metal-clad wires and tapes. Fe-clad MgB2 tapes were fabricated using a powder-in-tube technique. The tape shows a sharp transition with a transition width ΔTc of 0.2 K and a Tc0 of 37.5 K. An high transport critical current value of 1.7 × 104 A/cm2 for both 29.5 K in 1 Tesla and 33 K in zero applied field has been achieved. The effects of sintering time and temperature on the formation and critical current densities of Feclad MgB2 wires is also investigated. MgB2 wires were sintered for different periods of time at predetermined temperatures. In contrast to the common practice of sintering for several hours, results show that there is no need for prolonged heat treatment in the fabrication of Fe/MgB2 wires. A total time in the furnace of several minutes is enough to form nearly pure MgB2. Jc of 4.5×105 A/cm2 in zero field and above 105 A/cm2 in 2 T at 15 K has been achieved for Fe/MgB2 wires sintered for a short time. These findings substantially simplify the fabrication process, making it possible to have a continuous process for fabrication and reducing the costs for large-scale production of MgB2 wires. Ag and Cu clad MgB2 wires were also fabricated using an in-situ reaction method. The effects of a shorter than usual sintering on the critical current densities of Ag and Cu clad MgB2 wires were studied. For Ag clad wire Jc is improved by more than two times after the short period sintering process. Jc values of 1.2×105 A/cm2 in zero field and above 104 A/cm2 in 2 T at 20 K have been achieved for Ag clad MgB2 wire which is only sintered for a few minutes at 800 oC. However, a remarkable degree of reaction has been found between the superconducting cores and the sheath materials, leading to the formation of Cu2Mg and Ag3Mg for copper and silver clad wires, respectively. The results show that the short sintering causes less reaction between the magnesium and the sheath materials and markedly improves the critical current density. Our results also show that iron is still the best sheath material for MgB2 superconductor wire and tape. Sixteen-filament stainless steel/Fe/MgB2 wires were fabricated by the powder-in-tube method followed by groove rolling. Magnetic critical current densities of 3.4×105 A/cm2 in 0.5 T and about 1.9×105 A/cm2 in 1 T at 5 K were achieved. Results on transport Jc of solenoid coils up to 100 turns fabricated with Cu-sheathed MgB2 wires using a windreaction in-situ technique are reported. Despite the low density of the single core and some reaction between the Mg and the Cu-sheath, our results demonstrate that the decrease in transport Jc with increasing length of MgB2 wires is insignificant. Solenoid coils with diameters as small as 10 mm can be readily fabricated using a wind-reaction in-situ technique. The Jc of coils is essentially the same as for straight wires. Jc values of 133,000 A/cm2 and 125,000 A/cm2 at 4 K and self field have been achieved for small coil wound using Cu-sheathed tape and Cu-sheathed wire respectively. The results indicate that the MgB2 wires have potential for large scale applications. The effect of chemical doping on the superconductivity and critical current density of MgB2 superconductor is investigated. Enhancements in the Jc field performance as well as the irreversibility field were obtained due to chemical doping with both C and SiC nano-particles. Doping MgB2-x(SiC)x/2 with x = 0, 0.2 and 0.3 and a 10 wt% nano-SiC doped MgB2 sample, led to slight decrease in Tc and significantly enhanced Hc2, Hirr and Jc at high magnetic fields. Compared to the non-doped sample, Jc for the 10 wt% doped sample increased by a factor of 32 at 5 K and 8 T, 42 at 20 K and 5 T, and 14 at 30 K and 2 T. At 20 K, which is considered to be a benchmark operating temperature for MgB2, the best Jc for the doped sample was 2.4×105 A/cm2 at 2 T, which is comparable to Jc of the best Ag/Bi-2223 tapes. At 20 K and 4 T, Jc was 36,000 A/cm2, which is an order of magnitude higher than for the Fe/MgB2 tape. Our results show that there are two distinguishable but closely related mechanisms: increase of Hc2 and improvement of flux pinning that control the performance of Jc(H) in the samples. SiC-doping introduced many nano-scale precipitates and disorders at B and Mg sites, provoking a high resistivity of ρ (40K) = 300 μΩ-cm (RRR = 1.75) for the SiC-doped sample, leading to significant enhancement of both Hc2 and Hirr with only minor effects on Tc. EELS and TEM analysis revealed impurity phases: Mg2Si, MgO, MgB4, BOx, SixByOz, and BC at a scale below 10 m and an extensive domain structure of 2-4nm domains in the doped sample which serve as strong pinning centers. The effect of nano-SiC doping on the critical current density and flux pinning of Fe/MgB2 wires is also investigated. The depression of Tc with increasing SiC doping level remained rather small. High level SiC doping resulted in a substantial enhancement in the Jc(H) performance. The transport Jc for all the wires is comparable to the magnetic Jc at higher fields despite the low density of the samples. The transport Ic for the 10 wt% doped Fe/MgB2 wire reached 675 A at 24 K and 1 T (Jc = 140,000 A/cm2) and 500 A at 20 K and 2T (Jc = 103,000A/cm2). The transport Jc for the 10wt% SiC doped MgB2 wire is 30 times higher than for the undoped wire. SiC doped MgB2 polycrystalline samples were fabricated using different grain sizes (20 nm, 100 nm, and 37 μm) of SiC and different doping levels (0, 8, 10, 12, 15 wt %) in order to investigate the effect of the particle size of the starting SiC powder on the properties of samples. Results show that grain sizes of the starting precursors of SiC have a strong effect on the critical current density and its field dependence. The smaller the SiC grains are, the better the Jc field performance is. Significant enhancement of Jc and the irreversibility field Hirr were revealed for all the SiC doped MgB2 with additions up to 15 wt%. A Jc as high as 20,000 A/cm2 in 8 T at 5 K was achieved for the sample doped with 10 wt% SiC with a grain size of 20 nm. Results indicate that the nano-inclusions and substitution inside MgB2 are responsible for the enhancement of flux pinning. Polycrystalline MgB2-xCx samples with x=0.05, 0.1, 0.2, 0.3, 0.4 nano-particle carbon powder were prepared using an in-situ reaction method under well-controlled conditions to limit the extent of C substitution. It was found that both the a-axis lattice parameter and the Tc decreased monotonically with increasing doping level. However, for the sample doped with the highest nominal composition of x=0.4 the Tc dropped only 2.7 K. The nano-C doped samples showed an improved field dependence of the Jc compared with the undoped sample over a wide temperature range. The nhancement by C-doping is not as strong as for nano-SiC doped MgB2. X-ray diffraction results indicate that C reacted with Mg to form nano-size Mg2C3 and MgB2C2 particles. A study of ac susceptibility, magnetic shielding and the sample size effect is presented in Chapter 6. Systematic ac susceptibility measurements were performed on MgB2 bulk samples. It is shown that the flux creep activation energy is a nonlinear function of the current density U , indicating a nonlogarithmic relaxation of the current density in this material. The dependence of the activation energy on the magnetic field is determined to be a power law (J ) ∝ J −0.2 U(B) ∝ B−1.33 , showing a steep decline in the activation energy with magnetic field, which accounts for the steep drop in the critical current density with magnetic field that is observed in MgB2. Magnetic shielding was investigated by means of transport critical current measurements for Fe-sheathed MgB2 round wires. Strong magnetic shielding by the iron sheath was observed, resulting in a decrease in Ic by only 15% in a field of 0.6 T at 32 K. In addition to shielding, interaction between the iron sheath and the superconductor resulted in a constant Ic between 0.2 and 0.6 T. This was well beyond the maximum field for effective shielding of 0.2 T. This effect can be used to substantially improve the field performance of MgB2/Fe wires at fields at least 3 times higher than the range allowed by mere magnetic shielding by the iron sheath. The dependence of Ic on the angle between the field and the current showed that the transport current does not flow straight across the wire, but meanders between the grains. The effect of sample size on the critical current density and the flux pinning of pure and SiC doped MgB2 bulk samples has been investigated. At high fields a systematic degradation of magnetic Jc and Hirr was observed as the sample size decreased. However, Jc remarkably increased on decreasing the sample volume at low magnetic fields below 1 T. The SiC doped samples show less sample size effect than the pure samples, indicating a larger n-factor and therefore a stronger pinning effect due to SiC doping

The relevance of the self-field for the \u27peak effect\u27 in the transport Jc(H) of iron-sheathed MgB2 wires

Ferromagnetic sheath around a superconducting wire results in an unusual transport Jc(H). For the field perpendicular to the current, there is a plateau in Jc(H) at high temperatures and intermediate fields. This plateau develops into a peak at lower temperatures, resembling a “peak effect”. A model based on cancellation of the self-field of the current and external field within the iron sheath was proposed for the explanation of the plateau in Jc(H). We test this model in three key experiments. Firstly, we show that the form of Jc(H) for round MgB2/Fe wires is strongly temperature dependent. This is in contradiction with the model, because the properties of the iron sheath do not change in the measured temperature range. However, the temperature dependence of Jc might still account for the change of Jc(H). Secondly, the model requires a substantial component of the self-field to be parallel to the external field. Our measurements of Jc(H) for field parallel to the current show a peak in Jc(H) at high temperatures and a pronounced plateau at low temperatures. The model cannot explain this because the self-field and external field are perpendicular in this experiment. Thirdly, the iron sheath was made thinner on one side of the wire, which should produce an asymmetry in Jc(H) in the model for two different orientations of external field. Such asymmetry was not observed. These experiments show that the effect of the self-field is of much lower importance than a yet unknown effect that results in the observed plateau and peak in Jc(H). Such effect is likely to be based on a specific interaction between the superconductor and ferromagnet, perhaps similar to the overcritical state effect

Magnetic shielding in MgB2/Fe superconducting wires

Transport critical current (I/sub c/) was measured for MgB/sub 2//Fe round wires, with the magnetic field oriented perpendicular to the wire and parallel to it. Measurements were made on a wire with a pure MgB/sub 2/ core and another wire where the MgB/sub 2/ core was doped with nano-size SiC. This doping strongly improved the vortex pinning in MgB/sub 2/. The field dependence of I/sub c/ was strongly improved due to the presence of the iron sheath. At 30 K, I/sub c/ did not depend on the field for fields between 0.09 and 0.7 T. At lower temperatures, I/sub c/ increased with the field, after an initial decrease, resembling a peak effect. This effect was extended to higher fields as the temperature was decreased: at 10 K the peak appeared at 3.5 T. This improvement was not due to mere magnetic shielding by iron, but more likely to an interaction between the iron sheath and the superconductor. Improvement of vortex pinning did not affect the range of fields within which this effect was observed. J/sub c/ of SiC doped MgB/sub 2//Fe wires at elevated fields already satisfies the requirements for their use in production of superconducting magnets for particle accelerators

Effect of Henna (Lawsonia inermis) extract on the immunity and survival of common carp, Cyprinus carpio infected with Aeromonas hydrophila

Abstract In this study, the immunomodulatory properties of Lawsonia inermis (henna) in common carp, Cyprinus carpio was investigated. Fish were intraperitoneally (i.p.) injected with 6, 60 or 600 mg kg−1 body weight (BW), of the methanolic soluble fractions of L. inermis. The extract at 60 and 600 mg kg−1 BW, significantly (p < 0.05) enhanced some non-specific immune parameters such as serum lysozyme and bactericidal activity, phagocytic and respiratory burst activity, total leucocyte count (TLC), lymphocyte, monocyte and neutrophil number. Disease resistance against Aeromonas hydrophila has also been improved following herbal treatment. This preliminary study indicates the beneficial effect of L. inermis in improving immune status and controlling infectious diseases in aquaculture

Improvement of critical current in MgB2 superconducting wires by a ferromagnetic sheath

Transport critical current (Ic) was measured for Fe-sheathed MgB2 round wires. A critical current density of 5.3 x 10^4 A/cm^2 was obtained at 32K. Strong magnetic shielding by the iron sheath was observed, resulting in a decrease in Ic by only 15% in a field of 0.6T at 32K. In addition to shielding, interaction between the iron sheath and the superconductor resulted in a constant Ic between 0.2 and 0.6T. This was well beyond the maximum field for effective shielding of 0.2T. This effect can be used to substantially improve the field performance of MgB2/Fe wires at fields at least 3 times higher than the range allowed by mere magnetic shielding by the iron sheath. The dependence of Ic on the angle between field and current showed that the transport current does not flow straight across the wire, but meanders between the grains