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The photocatalytic degradation of tetracycline has been improved using H2O2-assisted Z-scheme-type heterojunction Bi3NbO7/Bi2Sn2O7 system under visible light irradiation. A possible photocatalytic degradation mechanism has been proposed.

On 7 June 2021, Juno had a close flyby of Jupiter’s moon Ganymede, flying within 1000 km of the surface. During the flyby, Juno’s Microwave Radiometer (MWR) observed Ganymede obtaining several swaths across Ganymede using Juno’s spin to partially map Ganymede’s ice shell in six channels ranging from 600 MHz to 22 GHz. The radiance at these frequencies originates from successively deeper layers of the sub-surface and may reach to depths of 20km at 0.6 GHz. The MWR observations cover a latitude range from 20S to 60N and an east longitude range from -120 to 60 degrees, roughly centered on the Perrine region. The local solar time varies from around noon to mid-night over the longitude range. We present resolved brightness temperature maps and associated microwave spectra of Ganymede with a spatial resolution of up to ~140 km (approximately 1/40th of Ganymede’s diameter). The microwave brightness temperature at all MWR wavelengths is anti-correlated with the visible brightness of the terrain, but is too large to be explained by albedo variations alone, suggesting sub-surface ice properties are not uniform with location. The dark regions tend to exhibit the warmest microwave spectra and brighter regions are observed to have a lower brightness temperature (up to half the blackbody temperature).The coldest microwave feature observed by MWR is the Tros crater and the immediate surrounding region. A radiative transfer algorithm, coupled with a thermal model for the conductive layer of Ganymede’s ice shell are fit to the MWR spectra providing an estimate of the conductive shell thickness. The microwave observations are globally colder than would be expected for pure water ice alone, suggesting thin highly reflective layer, possibly silicate dust, on the surface, although other interpretations remain possible. We suggest that scattering at sub-surface interfaces (e.g. fractures) explains the depressed brightness temperatures observed in brighter terrain types. Juno performed a close fly-by of Europa in September 2022, enabling a comparison of the sub-surface properties of these two icy satellites.

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Bi2Sr2Ca2Cu3O10+δ (Bi-2223) precursors for the fabrication of high temperature superconducting tapes were prepared by spray pyrolysis technique followed by a calcination process. The influences of precursor powder phase composition on the phase evolution dynamics and final current capacity of Bi-2223 superconducting tapes were systematically studied. It was interesting to notice that slight increase of Cu content in chemical composition could cause obvious variations of both the phase composition and the morphology of CuO particles in precursors. Therefore, the Bi-2223 phase formation process during the sintering process of tapes could be affected, and the current capacity changed accordingly. On the other hand, during the calcination temperature optimization process, the Bi-2223 phase content in precursors changed accordingly, thus the Bi-2223 phase formation dynamics were also studied. More Bi-2223 nuclei were formed due to the pre-existed Bi-2223 grains, which worked as inhomogeneous nuclei centers. Thus, although the final Bi-2223 phase contents were similar in all the tapes, the particle size and texture structure of Bi-2223 varied greatly, which caused a dramatic decrease of critical current in Bi-2223 tapes with the formation of Bi-2223 in precursors. Therefore, it could be concluded that both the morphology of CuO particles and the Bi-2223 phase content in precursors were the factors controlling the phase evolution dynamics during Bi-2223 tape sintering process.

FeSe superconducting bulks with different Fe contents were prepared by high energy ball milling aided sintering process followed by a post annealing process in low oxygen atmosphere. The influences of Fe content, annealing temperature and oxygen partial pressure have been systematically studied. It was found that both the critical temperature and superconducting phase volume ratio have been obviously improved with annealing. However, the effect of oxygen annealing process on FeSe polycrystalline bulks was different with that on FeSe single crystals. In polycrystalline bulks, the annealing process could further promote the phase transition from nonsuperconducting hexagonal δ-FeSe phase to superconducting tetragonal β-FeSe phase. Meanwhile, the chemical composition uniformity has also been enhanced with no obvious FeOδ phase detected by X-Ray Diffraction. With optimized annealing process under the oxygen partial pressure of 5% at 400 °C for 10 h, FeSe superconducting bulks have reached the critical temperature of 9.1 K.

A strain-rate-sensitive polyurethane elastomer is numerically investigated to reveal improved impact characteristics and analyze the concerned rate dependencies and dynamic energy dissipation features. A physical constitutive model in view of amorphous molecular structure of the elastomer is proposed by relating the macro-mechanical behaviors to micro-structural changes through molecular transitions and flow activations. Two distinct relaxation processes are considered because of entangled molecular networks, with each possessing a unique activation energy. Through calibration with experimental data, finite element simulations based on the model are conducted. Related to the loading rate, the structural entropy of molecular chain entanglements, rate-dependent yielding, plateau flow and densification are well predicted by the model. The investigations are extended further regarding the material recoverability and accordingly, strain energy absorptions are illustrated. A power law function is proposed for designing the energy absorption relation to the applied loading rate. Finally, the inherent mechanisms causing the dynamic energy absorptions are analyzed with notable clarifications of post-experimental observations obtained via scanning electron microscopy.

Fluorine doping Fe1.2Se polycrystalline were prepared by solid-state sintering method. The influences of fluorine doping content and sintering temperatures on phase composition, lattice parameters, microstructure as well as superconducting properties were discussed in detail. It was found that fluorine doping could effectively reduce the content of non-superconducting hexagonal δ-FeSe phase. Besides, the content of hexagonal δ-FeSe phase and grain size of superconducting tetragonal β-FeSe phase were decreased with the sintering temperature increasing. Scanning electron microscopes (SEM) images indicated that the morphology of β-FeSe phase was a typical lamellar structure with the small particles of hexagonal δ-FeSe phase. Meanwhile, a higher critical temperature Tc of 8.3 K and larger shield volume fraction were obtained with high sintering temperature of 950 °C and proper F doping content.

Bi2Sr2CaCu2O8+δ (Bi-2212)/Ag round wires were fabricated by imposing ultrasonic-vibration drawing (UVD) technique during both the single-filament and multi-filament cold-drawing processes. The frequency of ultrasonic-vibration was set fixed at 20 kHz and different output power density levels had been altered by varied amplitudes. The influence of ultrasonic-vibration on the deformation process of Ag metal sheath, filament density, Ag/superconductor ratio, wire dimension, drawing force reduction, and the superconducting properties of final wires has been systematically studied. Softening effect of ultrasonic-vibration on the Ag metal can be deduced with the decreasing drawing flow stress and drawing force under certain amplitude. It was found that powder densification could be promoted and higher filament volume fraction as well as high wire diameter uniformity had been reached with the introduction of UVD process, leading to the enhancement of Jc and JE after proper heat treatment. Such technique could be considered in fabrication of Bi-2212 long wires as well as other superconducting materials.

It is well known that the existence of interstitial Fe is a great obstacle to enhancing the superconducting properties of the Fe(Se, Te) system. In this work, a silver and oxygen codoping effect toward enhancement of the superconductivity and flux pinning in Fe(Se, Te) bulks is reported. The oxygen ions from SeO

Chang'e-3(CE-3) has been the first spacecraft to soft-land on the Moon since the Soviet Union's Luna 24 in 1976. The spacecraft arrived at Mare Imbrium on December 14, 2013 and the same day, Yutu lunar rover separated from lander to start its exploration of the surface and the subsurface around the landing site. The rover was equipped, among other instruments, with two Lunar Penetrating Radar systems (LPR) having a working frequency of 60 and 500 MHz. The radars acquired data for about two weeks while the rover was slowly moving along a path of about 114 m. At Navigation point N0209 the rover got stacked into the lunar soil and after that only data at fixed position could be collected. The low frequency radar data have been analyzed by different authors and published in two different papers, which reported totally controversial interpretations of the radar cross sections. The present study is devoted to resolve such controversy carefully analyzing and comparing the data collected on the Moon by Yutu rover and on Earth by a prototype of LRP mounted onboard a model of the CE-3 lunar rover. Such analysis demonstrates that the deep radar features previously ascribed to the lunar shallow stratigraphy are not real reflectors, rather they are signal artefacts probably generated by the system and its electromagnetic interaction with the metallic rover.

Precursor powders of Bi2Sr2Ca2Cu3O10+δ (Bi-2223) high temperature superconducting tapes were prepared with spray pyrolysis technique. By tuning the oxygen partial pressure in calcination atmosphere as 1.0%, 7.5%, and 10.0%, respectively, the influences of calcination atmosphere on the phase evolution dynamics during the precursor powders calcination process have been discussed. Then the optimal calcination temperatures have been obtained correspondingly. Moreover, Bi-2223 multi-filament tapes have been fabricated with the precursor powders calcinated under different atmosphere. The effects of precursor powder calcination parameters on the phase composition, microstructures as well as the current capacity of final tapes have been systematically studied. Due to the proper secondary phase content and enhanced Bi-2223 texture structures, the maximum critical current of 109 A at 77 K, self-field, corresponding to the critical current density of 23.3 kA cm−2 has been obtained with the oxygen partial pressure of 7.5% in calcination atmosphere and the calcination temperature of 790 °C.

Bi 1.76 Pb 0.34 Sr 1.93 Ca 2.02 Cu 3.06 O 10+δ (Bi-2223) high temperature superconducting tapes were fabricated with Powder in tube (PIT) process. The traditional drawing process was partially replaced by groove rolling. The influence of cold working method on the filament density, the phase evolution mechanism as well as superconducting properties has been systematically studied. The groove rolling process could obviously enhance the filament density of Bi-2223 green wires, which thus led to the change of Bi-2223 formation rate. Meanwhile, although the heat treatment process has not been thoroughly optimized, the residual secondary phase content was still high, the critical current has been improved for more than 20% with groove rolling process, which should be attributed to the improved intergrain connections. On the other hand, the groove rolling process was also effective on the fabrication of Bi-2223 tapes with larger filament number, such as 85 or 121 to maintain the uniformity of filament deformation.

30-core MgB2 superconducting wire with a diameter of 1.0 mm has been prepared by the conventional in-situ powder-in-tube (PIT) method. The metallographic analysis results show that the 30-core MgB2 wire has good uniformity in both transverse and longitudinal directions, and the critical current ( I c) and critical current density ( J c) at 4.2 K and 4 T reach 82.6 A and 7.3 × 104 A/cm2, respectively. Furthermore, (6 + 1)-structure MgB2 superconducting cables have also been successfully fabricated with different twist pitches ( T p) by the twisted and reacted (T&R) route, comprising six 30-core MgB2 wires around one copper wire in the center. The I c of the (6 + 1)-structure MgB2 superconducting cable with 50 mm T p reaches 467 A at 4.2 K and 4 T, suggesting no degradation of the MgB2 wire when self-field effects are taken into account.

In this work, practical kilometer-length 18- and 30-filament Monel/Nb/MgB2 wires have been prepared by in situ powder-in-tube (PIT) method, combing in the twisting of wires with twisting pitches (TP) of 5 mm, 10 mm, and 20 mm. Transport critical current density (Jc) properties at various temperatures and magnetic fields for MgB2 wires with different TP and the effects of the heat-treatment conditions and wire diameter size on the Jc of 30- filament wire have been investigated in detail. The results suggest the Jc of MgB2 wire without twisting at 4.2 K, 4 T, and 20 K, 3 T separately reaches 1.9 × 105 and 5.87 × 104 A/cm2 for 30-filament wire, and 1.48 × 105 and 4.4 × 104 A/cm2 for 18-filament wire. After twisting, as the TP reduction, the Jc degradation of MgB2 wire is much slower in 30-filament than that in 18-filament at various magnetic fields. At the TP of 5 mm, the Jc degradation comparing with the untwisted wires at 4.2 K and 4 T is up to 30% in 18-filament wire but only about 10% in the 30-filament. This work indicates that the twisting route is very promising to the engineering application of MgB2 superconductor.

Multifilamentary Bi2Sr2Ca2Cu3O10+δ (Bi-2223) high temperature superconducting tapes were fabricated by powder-in-tube process. During the precursor powder packing process, environment atmosphere was changed from pure oxygen to dry air and 7.5% O2 balanced with N2, with the oxygen partial pressure decreasing from 100% to 25% and 7.5%, respectively. The change of packing atmosphere obviously influenced the phase assemblage in the early stage of Bi-2223 phase formation process. Therefore, the chemical composition of obtained Bi-2223 phase as well as the content and distribution of secondary phases changed accordingly. Meanwhile, the changes of intergrain connections and the flux pinning properties were investigated based on the in-field critical current, $I_{c}$ – B measurements. Finally, attributed to the decreased oxygen partial pressure in packing atmosphere, the $I_{c}$ improvements of 25% at self-field and 0.6 T were obtained comparing with the tapes packed under pure oxygen. With further optimization of sintering process, the final $I_{c}$ of 116 A was achieved, which corresponded to the critical current density, $J_{c}$ of ∼21 kAcm−2.

During the metal–organic deposition (MOD) process, the carbon-rich impurities remaining in a film are harmful to the epitaxial growth of the oxide film. Thus, it is of great importance to investigate epitaxial growth of oxide films with different carbonaceous phases. To control the carbonaceous phases in the as-fabricated LZO film, different dopant concentrations and annealing atmospheres have been suggested during the MOD process. A characterization of specimens was performed using X-ray diffraction θ–2θ scans, out-of-plane and in-plane scans, X-ray photoelectron spectroscopy, electron backscattering diffraction, and atomic force microscopy. It was found that a small number of carbonaceous phases, regardless of their type, has no obvious negative influence on the growth orientation of the film. Moreover, because some bridge-pillar spots in the graphene layer enable the epitaxial growth of oxide film, the texture degree of LZO film doped with a high concentration of reduced graphene oxide (RGO) is even sharpened. With increasing doping RGO concentration, the surface roughness of the LZO film increases, which indicates an exaggerated impact of the surface defects on the metallic substrate on the grain size of the LZO film doped with RGO. Different oxygen partial pressures in the annealing atmosphere determine the type of carbonaceous phase in the as-prepared oxide film. The carbonate species formed in the film under high oxygen partial pressure have a negative influence on the texture degree and the surface flatness of LZO film, while low oxygen partial pressure favors the reduction of the residual carbon in the film. Therefore, oxide films with high performance can be achieved by controlling the presence of the positive carbonaceous phases in the film during the introduction of an appropriate artificial doping source and the selection of a suitable annealing atmosphere.

Superionic thermoelectric Cu2Se bulks are successfully acquired via an identical gas reinforced eutectic transformation (gasar) process based on its melting-congruent nature. The gasar synthesis process introduces tubular pores to Cu2Se matrix, which have hierarchical size and corrugated surface, and are distributed homogeneously and isotopically. The Cu2Se bulk with such a unique porous structure shows enhanced thermoelectric figure-of-merit up to ∼2.1 at 873 K owing to the conspicuously reduced thermal conductivity, which can be attributed to the increased phonon scattering. Moreover, the porous Cu2Se bulk also possesses higher mechanical robustness compared with traditional porous-structured material because of the corrugated surface, which is promising for making thermoelectric modules.

We have grown Cu2O films by different routes including self-oxidation and metal-organic deposition (MOD). The reduction efficiency of Cu2O films on graphene oxide (GO) synthesized by modified Hummer’s method has been studied. Surface morphology and chemical state of as-prepared Cu2O film and GO sheets reduced at different conditions have also been investigated using atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS). Results show that self-oxidation Cu2O film is more effective on phtocatalytic reduction of GO than MOD-Cu2O film. Moreover, reduction effect of self-oxidation Cu2O film to GO is comparable to that of environmental-friendly reducing agent of vitamin C. The present results offer a potentially eco-friendly and low-cost approach for the manufacture of reduced graphene oxide (RGO) by photocatalytic reduction.