The Preparation of a Challenging Superconductor Nb3Al by Exploiting Nano Effect.

The Nb3Al superconductor with excellent physical and working properties is one of the most promising materials in high-magnetic-field applications. However, it is difficult to prepare high-quality Nb3Al with a desired superconducting transition temperature (Tc) because of its narrow phase formation area at high temperatures (>1940 °C). This work reports a method to prepare stoichiometric Nb3Al powder samples at a relatively low temperature (1400 °C) by exploiting the nano effect of Nb particles with pretreatment of Nb powder under H2/Ar atmosphere. The obtained Nb3Al samples exhibit high Tc's of ~16.8K. Based on density functional theory (DFT) calculations and statistical mechanics analysis, the crucial role of quantum effect in leading to the success of the preparation method was studied. A new measure of surface energy (MSE) of a model particle is introduced to study its size and face dependence. A rapid convergence of the MSE with respect to the size indicates a quick approach to the solid limit, while the face dependence of MSE reveals a liquid-like behavior. The surface effect and quantum fluctuation of the Nbn clusters explain the success of the preparation method.

Topological Flat Bands in 2D Breathing-Kagome Lattice Nb3 TeCl7.

Flat bands (FBs) can appear in two-dimensional (2D) geometrically frustrated systems caused by quantum destructive interference (QDI). However, the scarcity of pure 2D frustrated crystal structures in natural materials makes FBs hard to be identified, let alone modulate FBs relating to electronic properties. Here, the experimental evidence of the complete electronic QDI induced FB contributed by the 2D breathing-kagome layers of Nb atoms in Nb3 TeCl7 (NTC) is reported. An identical chemical state and 2D localization characteristics of the Nb breathing-kagome layers are experimentally confirmed, based on which NTC is demonstrated to be a superior concrete candidate for the breathing-kagome tight-binding model. Furthermore, it theoretically establishes the tunable roles of the on-site energy over Nb sites on bandwidth, energy position, and topology of FBs in NTC. This work opens an aveanue to manipulate FB characteristics in these 4d transition-metal-based breathing-kagome materials.

Polarization-Independent Second Harmonic Generation in 2D Van Der Waals Kagome Nb3 SeI7 Crystals.

Second harmonic generation (SHG) of 2D crystals has been of great interest due to its advantages of phase-matching and easy integration into nanophotonic devices. However, the polarization-dependence character of the SHG signal makes it highly troublesome but necessary to match the laser polarization orientation relative to the crystal, thus achieving the maximum polarized SHG intensity. Here, it is demonstrated a polarization-independent SHG, for the first time, in the van der Waals Nb3 SeI7 crystals with a breathing Kagome lattice. The Nb3 triangular clusters and Janus-structure of each Nb3 SeI7 layer are confirmed by the STEM. Nb3 SeI7 flake shows a strong SHG response due to its noncentrosymmetric crystal structure. More interestingly, the SHG signals of Nb3 SeI7 are independent of the polarization of the excitation light owing to the in-plane isotropic arrangement of nonlinear active units. This work provides the first layered nonlinear optical crystal with the polarization-independent SHG effect, providing new possibilities for nonlinear optics.

NB-3 expression in endothelial cells contributes to the maintenance of blood brain barrier integrity in a mouse high-altitude cerebral edema model.

NB-3, a member of the contactin/F3 subgroup in the immunoglobulin superfamily, plays an important role in neural development and injury recovery. The blood brain barrier (BBB) is typically involved in the pathophysiology of neural disorders, such as hypoxic-ischemic brain injury. Our previous research found that NB-3 protects against brain damage in a mouse stroke model. However, its role in high-altitude disorders caused by hypobaric hypoxia exposure remains unknown. In the present study, we found that NB-3 was expressed in brain microvascular endothelial cells (BMECs) and responded to hypoxia stimulation. Conditional knockout of NB-3 in endothelial cells increased BBB leakage and downregulated tight junction proteins in vivo. NB-3 deficiency promoted the downregulation of tight junction proteins under Lipopolysaccharide (LPS)/hypoxia stimulation. Conversely, overexpression or supplementation with NB-3 alleviated endothelial barrier injuries. Transcriptome sequencing showed that NB-3 regulated various cell attachment genomic changes, including the Notch signaling pathway. Blocking the Notch signaling pathway increased VEGF/VEGFR2 pathway activation induced by LPS/hypoxia. Collectively, we present evidence that NB-3 plays key roles in maintaining BBB integrity under high-altitude cerebral edema conditions.

Constructing efficient HCSs/Nb3O7F hybrids based on bonding interaction to boost simulated-sunlight photocatalytic performance.

Recently, Nb3O7F (NOF) semiconductor has been intensively studied owing to its excellent ultraviolet activity, good thermal stability and low carrier recombination. In this work, we report a five-step technique to synthesize hollow carbon spheres (HCSs)/NOF hybrids. Activating the surface of HCSs by creating oxyfluorinated functionalization can easily trigger an interaction between oxyfluorinated HCSs and NOF intermediates, finally resulting in the formation of HCSs/NOF hybrids. By manipulating the contents of HCSs with unexceptionable electron mobility, the hybrids can simultaneously achieve narrower band gap, stronger light absorption and rapider charge transfer. As a consequence, HCSs/NOF hybrids exhibit enhanced photodegradation performance towards RhB solutions under simulated sunlight irradiation. Specially, HCSs/NOF-1.0 catalysts with 95.7% degradation efficiency within 40 min demonstrate approximately four times higher photocatalytic activity than that of pure NOF catalysts. The results may offer new inspirations for a design of novel catalysts with higher photoactivity.

In†Situ Corrosion Fabrication of NaNbO3 /Nb3 O7 F Heterojunctions with Optimized Band Realignment for Enhanced Photocatalytic Hydrogen Evolution.

Heterostructured photocatalysis is a significant issue owing to the unique band alignment, improved spectrum absorption, and enhanced photocatalytic activity. However, the construction of uniform, controllable, and effective heterojunctions is still a huge challenge. Herein, NaNbO3 /Nb3 O7 F heterojunctions are fabricated through an in situ corrosion technique for the first time. The influence of phase transformation on the hydrogen evolution reaction (HER) activity is investigated systematically in terms of photocatalytic water splitting for H2 production. Interestingly, the band realignment and good interfacial contact endow the NaNbO3 /Nb3 O7 F heterojunctions with a high HER activity (43.3 mmol g-1 h-1 ), which is about 2.4 times that of pure Nb3 O7 F and 1.36 times that of pure NaNbO3 . The results may provide some new insights into the corrosion technique and HER activity of novel heterostructured catalysts.

Nb/Sn Liquid-Solid Reactive Diffusion Couples and Their Application to Determination of Phase Equilibria and Interdiffusion Coefficients of Nb-Sn Binary System.

Nb3Sn plays an irreplaceable role in superconducting parts due to its stable performance under high field conditions. Accurate phase equilibria and interdiffusion coefficients are of great significance for designing novel Nb3Sn superconductors. However, the related experimental information is still in a state of scarcity because of the difficulty in fabrication of Nb-Sn alloys caused by the large difference in melting points of Nb and Sn. In this paper, a simple but pragmatic approach was first proposed to prepare the Nb/Sn liquid-solid reactive diffusion couples (LSDCs) at 1100 °C and 1200 °C, of which the phase identification of the formed layer and the measurement of composition-distance profiles were conducted. The formed layer in Nb/Sn LSDCs was confirmed to be Nb3Sn compound. While the measured composition profiles were employed to determine the phase equilibria according to the local equilibrium hypothesis and the interdiffusion coefficients with an aid of the latest version of HitDIC software. The determined phase equilibria of Nb3Sn, (Nb) and liquid show good agreement with the assessed phase diagram. While the calculated interdiffusion coefficients and activation energy for diffusion in Nb3Sn are consistent with both experimental and theoretical data in the literature. Moreover, the growth of the formed Nb3Sn layer in Nb/Sn LSDCs was also found to be diffusion controlled. All the obtained phase equilibria and interdiffusion coefficients are of great value for further thermodynamic and kinetic modeling of the Nb-Sn system. Furthermore, it is anticipated that the presently proposed approach of fabricating liquid-solid reactive diffusion couple should serve as a general one for various alloy systems with large differences in melting points.

High-Performance Two-Dimensional Perovskite Ca2Nb3O10 UV Photodetectors.

We first report two-dimensional (2D) perovskite Ca2Nb3O10 ultraviolet photodetectors (UV PDs), which are prepared via a facile calcination-exfoliation method. The 2D Ca2Nb3O10 PDs demonstrate high performance at 3 V at 280 nm, high responsivity (14.94 A W-1), high detectivity (8.7 × 1013 Jones), high spectral selectivity (R280/R400 = 8.84 × 103), fast speed (0.08/5.6 ms), and long-term stability, exceeding those of most reported UV PDs. Furthermore, the Ca2Nb3O10 PDs integrated with poly(ethylene terephthalate) (PET) show excellent flexibility and have high linear dynamic range (96 dB). Our work provides a general strategy for searching new UV PDs based on numerous layered niobates. The Ca2Nb3O10 nanosheets may be one of the optimum semiconductor materials for next-generation high-performance UV PDs.

A Study of the Effect of 5 at.% Sn on the Micro-Structure and Isothermal Oxidation at 800 and 1200 °C of Nb-24Ti-18Si Based Alloys with Al and/or Cr Additions.

This paper presents the results of a systematic study of Nb-24Ti-18Si based alloys with 5 at.% Sn addition. Three alloys of nominal compositions (at.%), namely Nb-24Ti-18Si-5Cr-5Sn (ZX4), Nb-24Ti-18Si-5Al-5Sn (ZX6), and Nb-24Ti-18Si-5Al-5Cr-5Sn (ZX8), were studied to understand how the increased Sn concentration improved oxidation resistance. In all three alloys there was macrosegregation, which was most severe in ZX8 and the primary ßNb5Si3 transformed completely to αNb5Si3 after heat treatment. The Nbss was not stable in ZX6, the Nb3Sn was stable in all three alloys, and the Nbss and C14-NbCr2 Laves phase were stable in ZX4 and ZX8. The 5 at.% Sn addition suppressed pest oxidation at 800 °C but not scale spallation at 1200 °C. At both temperatures, a Sn-rich area with Nb3Sn, Nb5Sn2Si, and NbSn2 compounds developed below the scale. This area was thicker and continuous after oxidation at 1200 °C and was contaminated by oxygen at both temperatures. The contamination of the Nbss by oxygen was most severe in the bulk of all three alloys. Nb-rich, Ti-rich and Nb and Si-rich oxides formed in the scales. The adhesion of the latter on ZX6 at 1200 °C was better, compared with the alloys ZX4 and ZX8. At both temperatures, the improved oxidation was accompanied by a decrease and increase respectively of the alloy parameters VEC (Valence Electron Concentration) and δ, in agreement with the alloy design methodology NICE (Niobium Intermetallic Composite Elaboration). Comparison with similar alloys with 2 at.% Sn addition showed (a) that a higher Sn concentration is essential for the suppression of pest oxidation of Nb-24Ti-18Si based alloys with Cr and no Al additions, but not for alloys where Al and Cr are in synergy with Sn, (b) that the stability of Nb3Sn in the alloy is "assured" with 5 at.% Sn addition, which improves oxidation with/out the presence of the Laves phase and (c) that the synergy of Sn with Al presents the "best" oxidation behaviour with improved scale adhesion at high temperature.

2D Perovskite Sr2 Nb3 O10 for High-Performance UV Photodetectors.

2D perovskites, due to their unique properties and reduced dimension, are promising candidates for future optoelectronic devices. However, the development of stable and nontoxic 2D wide-bandgap perovskites remains a challenge. 2D all-inorganic perovskite Sr2 Nb3 O10 (SNO) nanosheets with thicknesses down to 1.8 nm are synthesized by liquid exfoliation, and for the first time, UV photodetectors (PDs) based on individual few-layer SNO sheets are investigated. The SNO sheet-based PDs exhibit excellent UV detecting performance (narrowband responsivity = 1214 A W-1 , external quantum efficiency = 5.6 × 105 %, detectivity = 1.4 × 1014 Jones @270 nm, 1 V bias), and fast response speed (trise ≈ 0.4 ms, tdecay ≈ 40 ms), outperforming most reported individual 2D sheet-based UV PDs. Furthermore, the carrier transport properties of SNO and the performance of SNO-based phototransistors are successfully controlled by gate voltage. More intriguingly, the photodetecting performance and carrier transport properties of SNO sheets are dependent on their thickness. In addition, flexible and transparent PDs with high mechanical stability are easily fabricated based on SNO nanosheet film. This work sheds light on the development of high-performance optoelectronics based on low-dimensional wide-bandgap perovskites in the future.

Induced NB-3 Limits Regenerative Potential of Serotonergic Axons after Complete Spinal Transection.

NB-3 (contactin-6) is a member of the contactin family and has a wide range of roles during central nervous system development and disease. Here, we found that NB-3 was simultaneously induced in the serotonergic raphespinal tract (sRST) axons and in the scar-forming cells after spinal cord injury (SCI). Regrowth of sRST axons was promoted in vivo by blocking NB-3 expression in either sRST axons or scar-forming cells when post-traumatic axons of the sRST tried to penetrate the glial scar. NB-3 deficiency promoted synapse reformation between sRST regenerative axons and motor neurons and enhanced the potential for electrical activity of muscle contraction and motor coordination. In vivo evidence also suggested that NB-3 induction in both sRST axons and scar-forming cells was required to mediate NB-3 signaling inhibition of sRST axon regeneration after SCI. Our findings suggest that NB-3 protein is a potential molecular target for future SCI treatments.

First-Principles Calculations on Structural Property and Anisotropic Elasticity of γ1-Ti4Nb3Al9 under Pressure.

The effect of pressure on the structural property and anisotropic elasticity of γ 1 -Ti 4 Nb 3 Al 9 phase has been investigated in this paper by using first-principles calculations. The obtained bulk properties at zero pressure are in good agreement with the previous data. The structural property and elastic constants under pressures up to 40 GPa have been obtained. According to the elastic stability conditions under isotropic pressure, the phase is found to be mechanically stable under pressures up to 37.3 GPa. From the obtained elastic constants, the elastic moduli, anisotropic factors and acoustic velocities under different pressures have also been obtained successfully together with minimum thermal conductivities and Debye temperature. It is shown that the ductility of the phase is improved and its anisotropy and Debye temperature are enhanced with increasing the pressure.

A relação da arquitetura com os laboratórios de biossegurança de nível 3 (NB3) / The relationship of architecture with level biosafety laboratories 3 (NB3)

A arquitetura se manteve ao longo dos tempos lado a lado com as crenças mágicas e posteriormente os conceitos científicos sobre a transmissão de doenças, passando por transformações com a descoberta dos micro-organismos no final do século XIX, tornando-se uma grande aliada da biossegurança nos tempos atuais. O objetivo deste trabalho é identificar a relação da arquitetura com os laboratórios de biossegurança nível 3 (NB3). Para isso, três laboratórios NB3 em funcionamento atualmente, cujos projetos foram pioneiros no Brasil, foram analisados em termos de utilização e estrutura física (dividido em poros, carioteca e núcleo). Foram coletados dados através de levantamento arquitetônico, entrevista com o gestor e entrevista com os usuários dos três laboratórios. Após comparação entre essas características físicas, avaliação dos usuários e literatura existente, foram identificados pontos críticos de grande relevância envolvendo os parâmetros analisados dos laboratórios, entre eles os poros de vestiários de entrada e saída, bancadas, torneiras, parâmetros de bem estar e segurança, parâmetros que interferem no tamanho do laboratório e dutos aparentes de elétrica. Unindo a percepção dos usuários com o ponto de vista do arquiteto, conclui-se que os laboratórios NB3 devem ter seus parâmetros mais bem dimensionados, com especificações atuais e seguras, sem volumes sobre as superfícies e com espaço seguro e confortável para o usuário, coerente com os EPIs e o risco do laboratório. A arquitetura deve continuar o seu legado, tornando um espaço construído a representação física da ciência, e assim demonstrando, através de suas características, sua estreita relação com o conhecimento sobre a transmissão das doenças. (AU)

Architecture has remained throughout history side by side with magical beliefs and later scientific concepts about the transmission of diseases, going through transformations with the discovery of microorganisms in the late nineteenth century, becoming a great ally of biosafety in the present times. The objective of this work is to identify the relationship between the architecture and the biosafety laboratories level 3 (BSL-3). For this, three BSL-3 laboratories currently in operation, whose projects were pioneers in Brazil, were analyzed in terms of use and physical structure (divided into pores, nuclear membrane and core). Data were collected through architectural survey, interview with the manager and interview with users of the three laboratories. After comparing these physical characteristics, the users' evaluation and the existing literature, six critical points were identified as being of major relevance in the analyzed parameters of the laboratories, among them pores of entrance and exit vestibules, benches, taps, wellness parameters and safety, parameters that interfere with the size of the laboratory and apparent electrical ducts. Uniting users' perception with the architect's point of view, it is concluded that NB3 laboratories should have their parameters better sized, with current and safe specifications, with no volumes on the surfaces and with safe and comfortable space for the user, consistent with PPE and laboratory risk. Architecture must continue its legacy, making a constructed space the physical representation of science, and thus demonstrating, through its characteristics, its close relationship with knowledge about the transmission of diseases. (AU)

Temporal Cohorts of Lineage-Related Neurons Perform Analogous Functions in Distinct Sensorimotor Circuits.

Neuronal stem cell lineages are the fundamental developmental units of the brain, and neuronal circuits are the fundamental functional units of the brain. Determining lineage-circuitry relationships is essential for deciphering the developmental logic of circuit assembly. While the spatial distribution of lineage-related neurons has been investigated in a few brain regions [1-9], an important, but unaddressed question is whether temporal information that diversifies neuronal progeny within a single lineage also impacts circuit assembly. Circuits in the sensorimotor system (e.g., spinal cord) are thought to be assembled sequentially [10-14], making this an ideal brain region for investigating the circuit-level impact of temporal patterning within a lineage. Here, we use intersectional genetics, optogenetics, high-throughput behavioral analysis, single-neuron labeling, connectomics, and calcium imaging to determine how a set of bona fide lineage-related interneurons contribute to sensorimotor circuitry in the Drosophila larva. We show that Even-skipped lateral interneurons (ELs) are sensory processing interneurons. Late-born ELs contribute to a proprioceptive body posture circuit, whereas early-born ELs contribute to a mechanosensitive escape circuit. These data support a model in which a single neuronal stem cell can produce a large number of interneurons with similar functional capacity that are distributed into different circuits based on birth timing. In summary, these data establish a link between temporal specification of neuronal identity and circuit assembly at the single-cell level.

Tribocorrosion behaviour of a biomedical Ti-25Nb-3Mo-3Zr-2Sn alloy in Ringer's solution.

The tribocorrosion behaviour of biomaterial Ti-25Nb-3Mo-3Zr-2Sn alloy in Ringer's solution was evaluated by micro-abrasion experiments, electrochemical tests and scanning electron microscope (SEM) observations. Potentiodynamic polarization results suggested that the effect of particle concentration on the electrochemistry characteristic is greater than the applied load. When the particle concentration and applied load were 0.05g·cm-3 and 0.25N, respectively, the Ecorr reached the maximum as -0.381V. The micro-abrasion-corrosion results showed that the wear rates of the Ti-25Nb-3Mo-3Zr-2Sn alloy increased with increasing particle concentration and decreased as applied load increased. The wear rates acquired under various conditions regarding to the main wear mechanism of two-body grooving wear with less three-body rolling wear; three-body abrasive wear modes are more efficient at material loss than two-body wear. The variation in material loss indicated that the contribution of corrosion is lower than the contribution of micro-abrasion. The wear regime, wastage and micro-abrasion-corrosion synergy maps associated with the particle concentration and applied load were established to evaluate the tribocorrosion behaviour of the Ti-25Nb-3Mo-3Zr-2Sn alloy as a potential surgical implant material.

Micro-abrasion-corrosion behaviour of a biomedical Ti-25Nb-3Mo-3Zr-2Sn alloy in simulated physiological fluid.

The micro-abrasion-corrosion behaviour of the biomedical Ti-25Nb-3Mo-3Zr-2Sn alloy in Hank׳s solution with protein has been investigated using electrochemical measurements, tribological tests and scanning electron microscope (SEM) observations. The potentiodynamic polarization tests showed that the corrosion potential (Ecorr) exhibits the maximum value at the abrasive concentration of 0.05gcm(-3) despite of the load level. The tribological results indicated that the total material loss of the Ti-25Nb-3Mo-3Zr-2Sn alloy during micro-abrasion increased with the increasing abrasive concentration at a certain applied load. When the abrasive concentration is no more than 0.15gcm(-3), the total material loss increases with increasing load, while the total material loss exhibits the maximum value at a moderate load in case of higher abrasive concentration levels. This was ascribed to the three-body or two-body micro-abrasion-corrosion at different abrasive concentration levels. The wastage map, abrasion mode map and synergy map associated with the applied load and the abrasive concentration were constructed to evaluate the micro-abrasion-corrosion behaviour of the Ti-25Nb-3Mo-3Zr-2Sn alloy in potential biomedical applications.

NB-3 signaling mediates the cross-talk between post-traumatic spinal axons and scar-forming cells.

Little is known about the molecules mediating the cross-talk between post-traumatic axons and scar-forming cells after spinal cord injury. We found that a sustained NB-3 induction was simultaneously present in the terminations of post-traumatic corticospinal axons and scar-forming cells at the spinal lesion site, where they were in direct contact when axons tried to penetrate the glial scar. The regrowth of corticospinal axons was enhanced in vivo with NB-3 deficiency or interruption of NB-3 trans-homophilic interactions. Biochemical, in vitro and in vivo evidence demonstrated that NB-3 homophilically interacted in trans to initiate a growth inhibitory signal transduction from scar-forming cells to neurons by modulating mTOR activity via CHL1 and PTPσ. NB-3 deficiency promoted BMS scores, electrophysiological transmission, and synapse reformation between regenerative axons and neurons. Our findings demonstrate that NB-3 trans-homophilic interactions mediate the cross-talk between post-traumatic axons and scar-forming cells and impair the intrinsic growth ability of injured axons.

Developmental role of the cell adhesion molecule Contactin-6 in the cerebral cortex and hippocampus.

The gene encoding the neural cell adhesion molecule Contactin-6 (Cntn6 a.k.a. NB-3) has been implicated as an autism risk gene, suggesting that its mutation is deleterious to brain development. Due to its GPI-anchor at Cntn6 may exert cell adhesion/receptor functions in complex with other membrane proteins, or serve as a ligand. We aimed to uncover novel phenotypes related to Cntn6 functions during development in the cerebral cortex of adult Cntn6(-/-) mice. We first determined Cntn6 protein and mRNA expression in the cortex, thalamic nuclei and the hippocampus at P14, which decreased specifically in the cortex at adult stages. Neuroanatomical analysis demonstrated a significant decrease of Cux1+ projection neurons in layers II-IV and an increase of FoxP2+ projection neurons in layer VI in the visual cortex of adult Cntn6(-/-) mice compared to wild-type controls. Furthermore, the number of parvalbumin+ (PV) interneurons was decreased in Cntn6(-/-) mice, while the amount of NPY+ interneurons remained unchanged. In the hippocampus the delineation and outgrowth of mossy fibers remained largely unchanged, except for the observation of a larger suprapyramidal bundle. The observed abnormalities in the cerebral cortex and hippocampus of Cntn6(-/-) mice suggests that Cntn6 serves developmental functions involving cell survival, migration and fasciculation. Furthermore, these data suggest that Cntn6 engages in both trans- and cis-interactions and may be involved in larger protein interaction networks.

Highly Ordered Single Crystalline Nanowire Array Assembled Three-Dimensional Nb3O7(OH) and Nb2O5 Superstructures for Energy Storage and Conversion Applications.

Three-dimensional (3D) metal oxide superstructures have demonstrated great potentials for structure-dependent energy storage and conversion applications. Here, we reported a facile hydrothermal method for direct growth of highly ordered single crystalline nanowire array assembled 3D orthorhombic Nb3O7(OH) superstructures and their subsequent thermal transformation into monoclinic Nb2O5 with well preserved 3D nanowire superstructures. The performance of resultant 3D Nb3O7(OH) and Nb2O5 superstructures differed remarkably when used for energy conversion and storage applications. The thermally converted Nb2O5 superstructures as anode material of lithium-ion batteries (LiBs) showed higher capacity and excellent cycling stability compared to the Nb3O7(OH) superstructures, while directly hydrothermal grown Nb3O7(OH) nanowire superstructure film on FTO substrate as photoanode of dye-sensitized solar cells (DSSCs) without the need for further calcination exhibited an overall light conversion efficiency of 6.38%, higher than that (5.87%) of DSSCs made from the thermally converted Nb2O5 film. The high energy application performance of the niobium-based nanowire superstructures with different chemical compositions can be attributed to their large surface area, superior electron transport property, and high light utilization efficiency resulting from a 3D superstructure, high crystallinity, and large sizes. The formation process of 3D nanowire superstructures before and after thermal treatment was investigated and discussed based on our theoretical and experimental results.

Internally oxidized Nb3Sn strands with fine grain size and high critical current density.

Nb3Sn strands fabricated using Nb-Zr alloy can be internally oxidized, provided that oxygen is properly supplied via an oxide powder. This allows the formation of fine intragranular and intergranular ZrO2 particles in a Nb3Sn matrix. These particles can refine the grain size by a factor of three and thereby greatly enhance the Nb3Sn critical current density.