For quantum sensing based on nitrogen-vacancy (NV) centers in diamond, microwave irradiation with uniform power density and large detection volume is necessary to achieve ultrahigh sensitivity. We ...demonstrate the fabrication of a double magnetic ring stereoscopic antenna used for the tridimensional uniform control of NV spin ensembles with a 4π mm2 × 2 mm large volume. Compared with those of traditional microwave antennas (copper wire and single-loop antenna), the sensitivity of the sensor can be improved 4.93 and 9.98 times, and the linearity of the lock-in signal can be increased by 2.04 and 1.11%, respectively. Moreover, the proposed antenna can suppress the thermal noise generated by itself and is amenable to three-dimensional (3D) integration.
Bi2Te3-based materials have been reported to be one of the best room-temperature thermoelectric materials, and it is a challenge to substantially improve their thermoelectric properties. Here novel ...Bi2Te3 core fibers with borosilicate glass cladding were fabricated utilizing a modified molten core drawing method. The Bi2Te3 core of the fiber was found to consist of hexagonal polycrystalline nanosheets, and polycrystalline nanosheets had a preferential orientation; in other words, the hexagonal Bi2Te3 lamellar cleavage more tended to be parallel to the symmetry axis of the fibers. Compared with a homemade 3-mm-diameter Bi2Te3 rod, the polycrystalline nanosheets’ preferential orientation in the 89-μm-diameter Bi2Te3 core increased its electrical conductivity, but deduced its Seebeck coefficient. The Bi2Te3 core exhibits an ultrahigh ZT of 0.73 at 300 K, which is 232% higher than that of the Bi2Te3 rod. The demonstration of fibers with oriented nano-polycrystalline core and the integration with an efficient fabrication technique will pave the way for the fabrication of high-performance thermoelectric fibers.
As a frontier technology in radar imaging, hypersonic vehicle-borne (HSV) synthetic aperture radar (SAR) has several practical issues to be dealt with, namely, ground resolution capability, pulse ...repetition frequency (PRF) selection, and beam pointing description, especially for the near-vertical diving trajectory because of the extremely small angle between the velocity and slant range vectors. Moreover, its focusing approach design is greatly challenged by very large cross-couplings and spatial variations. Considering these practical problems, the constraints between system performance and parameter selection are analyzed firstly to obtain the parameter optimization procedure and avoid system design deviation. Then, a frequency radius/angle algorithm (FRAA) is devised, which is an extension of the radius/angle algorithm (RAA) performed in two-dimensional (2-D) frequency domain. In the FRAA, new range equation and 2-D frequency interpolation function are reconstructed with high accuracy by quadratic fitting and 3-D expansion. Compared with RAA, FRAA is more suitable for the HSV SAR with near-vertical diving trajectory. Simulation results verify the effectiveness of the proposed approach.
•Glass-cladding Bi2Se3 core thermoelectric fibers were fabricated.•The cores were found to be highly crystalline and phase-pure.•The Bi2Se3 core fibers exhibit an ultrahigh Seebeck coefficient.•It ...has a high ZT of 0.18 (at 300 K) and a long-term stability in air.
Bismuth selenide exhibits high thermoelectric performance, which is a promising candidate for thermal-electrical energy conversion. Here, Bi2Se3 core thermoelectric fibers with K9 glass cladding were fabricated by a molten core drawing method. The 50-μm-diameter Bi2Se3 core fibers exhibit an ultrahigh Seebeck coefficient of −150.85 μV/K. In addition, it has a high dimensionless figure of merit of 0.18 (at 300 K) and a long-term stability in air. The results indicate that the drawing approach is an effective way to fabricate high-performance and high-stability thermoelectric fibers, which will have potential application in fiber-integrated thermoelectric devices.
Melatonin plays a vital role in plant growth and development. In this study, we treated hydroponically grown tomato roots with various concentrations of exogenous melatonin (0, 10, 30, and 50 μmol·L
...). We utilized root scanning and microscopy to examine alterations in root morphology and cell differentiation and elucidated the mechanism by which melatonin regulates these changes through the interplay with endogenous hormones and relevant genes. The results showed that for melatonin at concentrations ranging between 10 and 30 μmol·L
, the development of lateral roots were significantly stimulated, the root hair growth was enhanced, and biomass accumulation and root activity were increased. Furthermore, we elucidated that melatonin acts as a mediator for the expression of genes, such as
,
,
,
, and
, which are involved in the regulation of root morphology changes. Additionally, we observed that melatonin influences the levels of endogenous hormones, including ZT, GA3, IAA, ABA, and BR, which subsequently impact the root morphology development of tomato roots. In summary, this study shows that tomato root morphology can be promoted by the optimal concentration of exogenous melatonin (10-30 μmol·L
).
Tin selenide (SnSe) exhibits high thermoelectric (TE) performance, which is a promising TE candidate for thermal-electrical energy conversion. In this work, Sn-Se alloy core borosilicate glass-clad ...fibers with ∼94 μm core and ∼220 μm cladding in diameter were fabricated by a molten core drawing method. X-ray diffraction (XRD) showed the core to be highly crystalline and consist of SnSe and SnSe2 poly-crystal grains. Based on EPMA measurement, there exists an inter-diffusion process between the core and cladding ions during the fiber drawing. The Seebeck coefficient of the Sn-Se core is −151 μV/K. The electrical conductivity of the Sn-Se core is as high as 6.2 × 103 S/m, which is close to that of SnSe single crystals. The demonstration of fibers with TE core materials and the integration with the conventional fiber fabrication technique represents the first step in providing the building blocks for fiber-integrated TE devices.
•Sn-Se alloy core silicate glass-clad fibers were successfully fabricated.•The cores were confirmed to be highly crystalline and consist of SnSe and SnSe2 phases.•The fibers exhibit a high electrical conductivity close to SnSe single crystal at 900 K.•The fibers have promising applications in the field of thermoelectric energy conversion.
•Glass-clad In4Se3 core thermoelectric fibers were successfully synthesized.•The In4Se3 core in fibers exhibit an outstanding Seebeck effect.•The In4Se3 core fibers have potential utility in ...thermoelectric conversion.
In4Se3 exhibits high thermoelectric performance as a typical example of semiconductors, which is a promising thermoelectric candidate for energy conversion applications. Here, InSe alloy core thermoelectric fibers with glass cladding were fabricated by a reactive molten core drawing method. The as-drawn fiber core was found to be InSe crystals as evidenced by X-ray diffraction. The In4Se3 crystals were obtained in the fiber core by annealing the as-drawn fibers. The Seebeck coefficient of the In4Se3 core fibers (−347 μV/K) was enhanced by ∼85% compared with that of the as-drawn InSe core fibers (−189 μV/K). This work constitutes a proof-of-concept that thermoelectric materials can be incorporated into fibers, which have promising applications in fiber-based thermoelectric devices.
The importance of exploring Mars is self-evident, Mars's extremely low atmospheric density, resulting in Mars drones must have enough light weight. Multi-rotor unmanned aerial vehicle (UAV) with ...flexible racks offer another possibility for the lightweight design of Mars Rotorcraft. Based on the unique atmospheric environment of Mars, a flexible rotorcraft with ultra-light structure is designed in this paper, and the stability control of this flexible UAV is studied. A compound stability augmentation control system is proposed, which adopts PID controller as the main controller and L1 adaptive controller as the composite controller with output feedback to realize the stable flight of flexible Mars UAV. And through the flight experiment, it is proved that the designed controller has a good stability control effect for the flexible Mars UAV.
A new type of thermally sensitive fibers with an antimony selenide (Sb2Se3) core and phosphate glass cladding is demonstrated. The fibers were fabricated by a molten core method and maintained ...overall diameters ranging from 250 to 800 μm and core diameters of 35–200 μm. A 2.8 cm long Sb2Se3 core fiber, electrically contacted to external circuitry through fiber end facets, exhibited a four orders of magnitude change in conductivity after the whole fiber was heated from 25 to 195 °C. In addition, the fiber exhibited enhanced photoconductivity under illumination. These results indicate that Sb2Se3 core multimaterial fibers have promising applications in temperature sensing, optical switches and photodetectors.
•Phosphate glass-clad antimony selenide core fibers were successfully synthesized.•The cores were confirmed to be highly crystalline and phase-pure.•The fibers can detect light incident on it from at any point along its entire length.•The fibers exhibit a four-orders-of-magnitude change in conductivity at 195 °C.•The fibers have promising applications in photodetector and temperature sensing.
Solution-processed organo-lead halide perovskites have emerged as promising optical gain media for tunable coherent light sources. The lasing performance is generally determined by the as-synthesized ...crystal quality. Noble metal nanostructures have been widely utilized to enhance optical responses due to their unique property of localized surface plasmon resonance. Herein, we report a simple method to enhance the near-infrared amplified spontaneous emission (ASE) performance of MAPbI3 polycrystalline films by solution-processing a PMMA spacer layer and an Au NR-doped PMMA top layer on perovskite thin films. As a result, the ASE threshold of the triple-layer perovskite film was significantly reduced by around 36% and the ASE intensity increased by 13.9-fold, compared to the pristine film. The underlying mechanism was attributed to the combined effects of surface passivation by PMMA and plasmon resonance enhancement of Au NRs. The passivation effect results in suppressing the nonradiative recombination and prolonging excited state decay, which have been investigated by transient absorption and pump-probe measurements. The plasmon effect is systematically studied through distance-dependent and spectra-dependent plasmon enhanced emission. The perovskite films with PMMA and Au NR coating showed great stability for 180 min under intense pulse laser continuous irradiation. The improved ASE performance still remained after leaving the film under the atmosphere for more than one month. We have successfully demonstrated a highly stable and sustained ASE output from MAPbI3 films under pulse laser excitation. This study provides a general approach for exploring plasmonic nanostructures in combination with polymers in the development and application of low-cost solution-processed semiconductor lasers.
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