Encapsulation strategies are widely used for alleviating dissolution and diffusion of polysulfides, but they experience nonrecoverable structural failure arising from the repetitive severe volume ...change during lithium-sulfur battery cycling. Here we report a methodology to construct an electrochemically recoverable protective layer of polysulfides using an electrolyte additive. The additive nitrogen-doped carbon dots maintain their "dissolved" status in the electrolyte at the full charge state, and some of them function as active sites for lithium sulfide growth at the full discharge state. When polysulfides are present amid the transition between sulfur and lithium sulfide, nitrogen-doped carbon dots become highly reactive with polysulfides to form a solid and recoverable polysulfide-encapsulating layer. This design skilfully avoids structural failure and efficiently suppresses polysulfide shuttling. The sulfur cathode delivers a high reversible capacity of 891 mAh g
at 0.5 C with 99.5% coulombic efficiency and cycling stability up to 1000 cycles at 2 C.
Phosphorescence is a fascinating photoelectronic phenomenon usually observed in rare-earth-doped inorganic crystals and organic molecular crystals, owning great potential in optical information ...storage, color display and biological dosimetry. Here, we present an ultralong intrinsic phosphorescence (>20,000 seconds) in AlN single-crystal scintillator through X-ray excitation. We suggest that the long afterglow emission originates from the intra-band transition related to native nitrogen vacancy. Some excited states formed by absorbing X-ray photons cannot satisfy the parity difference between initial and final states required by transition selection rule, so they cannot return to the ground state directly through radiation transitions but through several phonon-assisted intra-band transitions slowly. During this process, a long-term broad-spectra phosphorescence emission is formed. Investigating the X-ray excited phosphorescence emission in the AlN is of great significance to understanding the mechanism of phosphorescence in inorganic materials, and to realizing the practical applications in high-energy ray dosimetry.
Abstract
Low-dimensional perovskite materials and their derivatives with excellent optical performance are promising candidates for light-emission applications. Herein, centimeter lead-halide Cs
4
...PbBr
6
single crystals (SCs), which have been used for radiation detection with the indirect conversion method, were synthesized by a facile solution process. The Cs
4
PbBr
6
scintillator exhibits bright green emission peaking at 525 nm and a high photoluminescence quantum yield (up to 86.7%) under 375 nm laser excitation. The Cs
4
PbBr
6
SCs exhibit high sensitivity to 40 keV X-rays, with a favorable linearity with the X-ray exposure dose rate, and the detection limit is as low as 64.4 nGy
air
/s. The scintillation time-response performance of the Cs
4
PbBr
6
SCs was acquired by a time-correlated single-photon counting system under alpha-particle excitation. The Cs
4
PbBr
6
SCs exhibit a very fast time response (
τ
av
= 1.46 ns) to alpha particles from a
241
Am radiation source. This value is comparable to that of the commercial plastic scintillator EJ-228 (
τ
av
= 1.31 ns) and much faster than that of the LYSO(Ce) scintillator (
τ
av
= 36.17 ns). Conceptual X-ray imaging and alpha-particle pulse height spectroscopy experiments were also performed. These results demonstrated the potential of Cs
4
PbBr
6
SCs for radiation detection applications, including X-ray imaging and charged particle detection with fast scintillation decay time and high sensitivity.
Abstract
Nontrivial topological structures offer a rich playground in condensed matters and promise alternative device configurations for post-Moore electronics. While recently a number of polar ...topologies have been discovered in confined ferroelectric PbTiO
3
within artificially engineered PbTiO
3
/SrTiO
3
superlattices, little attention was paid to possible topological polar structures in SrTiO
3
. Here we successfully create previously unrealized polar antivortices within the SrTiO
3
of PbTiO
3
/SrTiO
3
superlattices, accomplished by carefully engineering their thicknesses guided by phase-field simulation. Field- and thermal-induced Kosterlitz–Thouless-like topological phase transitions have also been demonstrated, and it was discovered that the driving force for antivortex formation is electrostatic instead of elastic. This work completes an important missing link in polar topologies, expands the reaches of topological structures, and offers insight into searching and manipulating polar textures.
Semiconductive metal–organic frameworks (MOFs) have attracted extraordinary research interest in recent years; however, electronic applications based on these emerging materials are still in their ...infancy. Herein, we show that a lanthanide-based semiconductive MOF (SCU-12) can effectively convert X-ray photons to electrical current signals under continuous hard X-ray radiation. The semiconductive MOF-based polycrystalline detection device presents a promising X-ray sensitivity with the value of 23.8 μC Gyair –1 cm–2 under 80 kVp X-ray exposure, competitive with the commercially available amorphous selenium (α-Se) detector. The lowest detectable X-ray dose rate is 0.705 μGy s–1, representing the record value among all X-ray detectors fabricated by polycrystalline materials. This work discloses the first demonstration of hard radiation detection by semiconductive MOFs, providing a horizon that can guide the synthesis of a new generation of radiation detection materials by taking the advantages of structural designability and property tunability in the MOF system.
To control an exoskeleton robot, gait event (phase) of the robot needs to be identified. This paper presents a novel gait event detection method for a lower extremity exoskeleton robot based on an ...intelligent inertial measurement unit (iIMU). The iIMU is designed as a gait monitor to independently accomplish data sampling, data processing, and wireless transmission. It also has good portability that can be easily attached on the surface of a shoe. Moreover, an online detection algorithm is proposed to detect the gait events by local search windows and fixed thresholds, resulting in a minimal time delay and small computational burden. The accuracy and detection rate of the iIMU are experimentally verified by 10 healthy subjects walking on a force plate and treadmill. The mean time errors of heel-strike and toe-off detection are -10 and 19 ms when compared to the force plate. Gait events of a total 478 steps, collected from a treadmill with various walking speeds, are all detected. When applied to a lower extremity exoskeleton robot, the iIMU successfully detects the gait events of the human-robot synchronous walk.
Low hardness and poor wear resistance are major limitations of Al alloys, which hinder their application in several fields, especially automotive moving parts. DLC can effectively improve hardness ...and wear resistance of Al alloys, but high residual stress and poor adhesion limit the film thickness. Multilayer thick films (~10 μm) composed of alternating Ti and Ti-DLC layers were successfully deposited on Al alloys. The influence of Ti content on the microstructure, mechanical and tribological properties of the film was emphasized. As the Ti content decreased from 10.42 to 1.35 at.%, the microstructure evolved from a polycrystalline composite film to a nanocrystalline composite film, and then to an amorphous film. The mechanical and tribological properties of the film depended on the microstructure. The amorphous composite film (Ti >6.06 at.%) exhibited better wear resistance than the polycrystalline composite film (Ti <6.06 at.%) due to the higher H/E⁎ (>0.1), H3/E⁎2 (>0.2) and elastic recovery (>60%). When the doped Ti content was 6.06 at.%, the nanocrystalline composite multilayer film showed superior comprehensive performance of high hardness (~23 GPa), high elastic recovery (~69%), low friction coefficient (~0.13) and low wear rate (1.0 × 10−7 mm3/Nm).
Display omitted
•Multilayer Ti-DLC thick films are successfully deposited on Al alloys by FCVA technology.•Microstructure of Ti-DLC films depends on Ti content precisely controlled by adjusting C2H2 flow rate.•Relationship between microstructure, mechanical and tribological properties of Ti-DLC films is studied.
Ferroptosis, a novel form of programmed cell death, is characterized by iron-dependent lipid peroxidation and has been shown to be involved in multiple diseases, including cancer. Stimulating ...ferroptosis in cancer cells may be a potential strategy for cancer therapy. Therefore, ferroptosis-inducing drugs are attracting more attention for cancer treatment. Here, we showed that erianin, a natural product isolated from Dendrobium chrysotoxum Lindl, exerted its anticancer activity by inducing cell death and inhibiting cell migration in lung cancer cells. Subsequently, we demonstrated for the first time that erianin induced ferroptotic cell death in lung cancer cells, which was accompanied by ROS accumulation, lipid peroxidation, and GSH depletion. The ferroptosis inhibitors Fer-1 and Lip-1 but not Z-VAD-FMK, CQ, or necrostatin-1 rescued erianin-induced cell death, indicating that ferroptosis contributed to erianin-induced cell death. Furthermore, we demonstrated that Ca
/CaM signaling was a critical mediator of erianin-induced ferroptosis and that blockade of this signaling significantly rescued cell death induced by erianin treatment by suppressing ferroptosis. Taken together, our data suggest that the natural product erianin exerts its anticancer effects by inducing Ca
/CaM-dependent ferroptosis and inhibiting cell migration, and erianin will hopefully serve as a prospective compound for lung cancer treatment.
Topologically nontrivial polar structures are not only attractive for high-density data storage, but also for ultralow power microelectronics thanks to their exotic negative capacitance. The vast ...majority of polar structures emerging naturally in ferroelectrics, however, are topologically trivial, and there are enormous interests in artificially engineered polar structures possessing nontrivial topology. Here we demonstrate reconstruction of topologically trivial strip-like domain architecture into arrays of polar vortex in (PbTiO
)
/(SrTiO
)
superlattice, accomplished by fabricating a cross-sectional lamella from the superlattice film. Using a combination of techniques for polarization mapping, atomic imaging, and three-dimensional structure visualization supported by phase field simulations, we reveal that the reconstruction relieves biaxial epitaxial strain in thin film into a uniaxial one in lamella, changing the subtle electrostatic and elastostatic energetics and providing the driving force for the polar vortex formation. The work establishes a realistic strategy for engineering polar topologies in otherwise ordinary ferroelectric superlattices.
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