Thermally recovered mechanoluminescence in Ca6BaP4O17:Eu2.

Stable reproducibility of mechanoluminescence (ML) is of vital importance for trap-controlled ML materials. Photo/electric excitation is usually needed for ML recovery of trap-controlled materials. In this work, it is demonstrated that thermal treatment can be applied to achieve recovery of ML, which is ascribed to the unique trap level configuration. The Ca6BaP4O17:Eu2+ performing robust trap-controlled ML has been proposed, and the corresponding repetitive ML can be realized by thermal treatment. TL spectra reveal that the thermally induced reproducible ML benefits from the dual defect level electronic structure of Ca6BaP4O17:Eu2+. The ML intensity is dependent on the electrons in shallow traps, and the electron transfer from deep traps to shallow traps induced by thermal treatment leads to repetitive ML.

Orbit constraint of a small bead on a rotating large circular hoop in a horizontal plane.

Orbit constraint problems can be encountered in mechanical equipment and amusement equipment. Mechanics exercises generally consider the ideal physical model, and the practical problems also consider the influence of friction, which makes the problem more complex and and practical. The problem of the force and oscillation of objects on orbit needs to be deeply discussed. In order to simulate the orbital motion of objects more realistically and help students expand their theoretical mechanics beyond class, we study the orbit constraint of a small bead on a rotating large circular hoop in a horizontal plane about an axis passing through a point on the circumference. The coupling equations followed by the bead on the hoop are derived using Newton's second law in a planar polar coordinate system and solved by numerical methods. We found that under the action of friction, when the initial angular velocity of the bead is greater than the critical angular velocity, the bead will rotate on the ring, and the number of rotations is related to the initial angular velocity and influenced by the friction coefficient. At different initial angular velocities, the number of oscillations of the bead on the hoop is basically the same and ultimately stops near the fixed point.

Pd-catalyzed ortho-C-H arylation of free anilines with arylboric acids forming o-amino biaryls.

We report a Pd-catalyzed ortho-C-H arylation of free anilines with arylboric acids. Under the reaction conditions, a wide range of arylboric acids can couple with free anilines to produce the corresponding o-amino biaryls in moderate to good yields with good functional group tolerance. This reaction can be conducted on the gram scale. The products can be easily further functionalized via transformation of the free amino group. These results indicate the potential synthetic value of this new reaction in organic synthesis.

Research on crack propagation behaviour of EB-PVD TBCs based on TGO evolution.

Thermal Barrier Coatings (TBCs) are functional coatings used to protect high-temperature components that are prone to early damage and premature failure under the influence of complex working conditions. This paper examines the crack propagation behaviour of 8% yttria-stabilized zirconia (8YSZ) EB-PVD TBCs under different oxidation conditions at 1100 °C. The morphology of interfacial cracks after oxidation was summarized and the evolution of thermally grown oxide (TGO) was quantified. Based on the evolution of TGO, the causes of crack propagation were analyzed. For the specimens after oxidation experiment, the interfacial crack propagation behaviour was observed and analyzed by SEM, and the reason of lateral crack propagation was explained from the perspective of interfacial fracture toughness. The reason for crack deflection is analyzed from the perspective of energy release rate. The equivalent thickness, normalized rumpling index and two-dimensional roughness index were calculated, then the TGO growth behaviour was comprehensively analyzed and related to the crack propagation.

Role of Native Defects in Fe-Doped ß-Ga2O3.

Iron impurities are believed to act as deep acceptors that can compensate for the n-type conductivity in as-grown Ga2O3, but several scientific issues, such as the site occupation of the Fe heteroatom and the complexes of Fe-doped ß-Ga2O3 with native defects, are still lacking. In this paper, based on first-principle density functional theory calculations with the generalized gradient approximation approach, the controversy regarding the preferential Fe incorporation on the Ga site in the ß-Ga2O3 crystal has been addressed, and our result demonstrates that Fe dopant is energetically favored on the octahedrally coordinated Ga site. The structural stabilities are confirmed by the formation energy calculations, the phonon dispersion relationships, and the strain-dependent analyses. The thermodynamic transition level Fe3+/Fe2+ is located at 0.52 eV below the conduction band minimum, which is consistent with Ingebrigtsen's theoretical conclusion, but slightly smaller than some experimental values between 0.78 eV and 1.2 eV. In order to provide direct guidance for material synthesis and property design in Fe-doped ß-Ga2O3, the defect formation energies, charge transitional levels, and optical properties of the defective complexes with different kinds of native defects are investigated. Our results show that VGa and Oi can be easily formed for the Fe-doped ß-Ga2O3 crystals under O-rich conditions, where the +3 charge state FeGaGai and -2 charge state FeGaOi are energetically favorable when the Fermi level approaches the valence and conduction band edges, respectively. Optical absorption shows that the complexes of FeGaGai and FeGaVGa can significantly enhance the optical absorption in the visible-infrared region, while the energy-loss function in the ß-Ga2O3 material is almost negligible after the extra introduction of various intrinsic defects.

Stiffness Variable Polymer for Soft Actuators with Sharp Stiffness Switch and Fast Response.

Stiffness variable polymers are an essential family of materials that have aroused considerable attention in soft actuators. Although lots of strategies have been proposed to achieve variable stiffness, it remains a formidable challenge to achieve a polymer with a wide stiffness range and fast stiffness change. Herein, a series of variable stiffness polymers with a fast stiffness change and wide stiffness range were successfully synthesized, and the formulas were optimized via Pearson correlation tests. The rigid/soft stiffness ratio of the designed polymer samples can reach up to 1376-folds. Impressively, owing to the phase-changing side chains, the narrow endothermic peak can be observed with full width at half-maximum within 5 °C. Moreover, the shape memory properties of the shape fixity (Rf) and shape recovery ratio (Rr) values of the shape memory properties could reach up to 99.3 and 99.2%, respectively. Then, the obtained polymer was introduced into a kind of designed 3D printing soft actuator. The soft actuator can achieve sharp heating-cooling cycle of 19 s under a 1.2 A current with 4 °C water as coolant and can lift a 200 g weight at the actuating state. Moreover, the stiffness of the soft actuator can reach up to 718 mN/mm. The soft actuator exhibits an outstanding actuate behavior and stiffness switchable capability. We expect our design strategy and obtained variable stiffness polymers to be potentially applied in soft actuators and other devices.

Can Digital Finance Promote Comprehensive Carbon Emission Performance? Evidence from Chinese Cities.

Improving urban comprehensive carbon emission performance (CCEP) is the inevitable choice for China's low-carbon development. With the continuous integration of digital technology and financial elements, the development of urban digital finance has also been significantly improved. To further explore the impact of urban digital finance on urban low-carbon development, using the data of 281 cities in China from 2011 to 2019, this paper firstly evaluates the urban CCEP, and further empirically investigates how digital finance influences CCEP. The empirical results show that: (1) Digital finance significantly improves the urban CCEP, and after conducting robustness tests and addressing the endogeneity issue, the above conclusion is robust. (2) For the sub-indicators, there is a U-shaped relationship between the coverage breadth of digital finance and CCEP. Moreover, the improvement of usage depth and digital support services could promote CCEP. (3) The channel tests indicate that digital finance improves the CCEP mainly by promoting green technology innovation and the development of urban tertiary industry. Meantime, digital finance has a stronger impact on improving CCEP in cities with more developed traditional finance, and the positive effect is significant in non-old industrial base cities and a two-control zone. Finally, this paper puts forward relevant policy suggestions.

Toward high-power-density laser-driven lighting: enhancing heat dissipation in phosphor-in-glass film by introducing h-BN.

In this work,  hexagonal boron nitride (h-BN) nanocrystals as functional additives in a phosphor-in-glass film are shown to substantially increase the luminous performance driven by a blue laser. Microstructural and spectroscopic studies reveal that h-BN particles distributed over the whole glass matrix build in situ a local heat conductive path which effectively accelerates heat dissipation and so greatly relieves the "thermal run-away effect". The developed composite material with fine thermal manipulation may be a promising phosphor color converter for high-power-density laser-driven lighting.

K+-doping-induced highly efficient red emission in CsPb(Br,I)3 quantum dot glass toward Rec. 2020 displays.

It is demonstrated that the incorporation of K+ into CsPb(Br,I)3 perovskite quantum dot glass leads to the simultaneous increases of quantum efficiency and phase stability. The latent mechanism is analyzed via the microstructural and spectroscopic studies. The constructed prototype white-light-emitting diode device yields an ultra-wide color gamut attaining 96% Rec. 2020 standard.

Sevoflurane Ameliorates Schizophrenia in a Mouse Model and Patients: A Pre-Clinical and Clinical Feasibility Study.

BACKGROUND: GABAergic deficits have been considered to be associated with the pathophysiology of schizophrenia, and hence, GABA receptors subtype A (GABAARs) modulators, such as commonly used volatile anesthetic sevoflurane, may have therapeutic values for schizophrenia. The present study investigates the therapeutic effectiveness of low-concentration sevoflurane in MK801-induced schizophrenia-like mice and schizophrenia patients. METHODS: Three weeks after MK801 administration (0.5 mg kg-1, i.p. twice a day for 5 days), mice were exposed to 1% sevoflurane 1hr/day for 5 days. Behavioral tests, immunohistochemical analysis, western blot assay, and electrophysiology assessments were performed 1-week post-exposure. Ten schizophrenia patients received 1% sevoflurane 5 hrs per day for 6 days and were assessed with the Positive and Negative Syndrome Scale (PANSS) and the 18-item Brief Psychiatric Rating Scale (BPRS-18) at week 1 and week 2. RESULTS: MK801 induced hypolocomotion and social deficits, downregulated expression of NMDARs subunits and postsynaptic density protein 95 (PSD95), reduced parvalbumin - and GAD67-positive neurons, altered amplitude and frequency of mEPSCs and mIPSCs, and increased the excitation/inhibition ratio. All these changes induced by MK-801 were attenuated by sevoflurane administration. Six and eight patients achieved a response defined as a reduction of at least 30% in the PANSS total score at 1st and 2nd week after treatments. The BPRS-18 total score was found to be significantly decreased by 38% at the 2nd week (p < 0.01). CONCLUSION: Low-concentration sevoflurane effectively reversed MK801-induced schizophrenialike disease in mice and alleviated schizophrenia patients' symptoms. Our work suggests sevoflurane to be a valuable therapeutic strategy for treating schizophrenia patients.

Laser-direct-writing of molecule-like Agmx+ nanoclusters in transparent tellurite glass for 3D volumetric optical storage.

In situ constructing program-designed nanostructures via laser-direct-writing (LDW) has proved to be a reliable strategy for optical storage (OS). Herein, a kind of low-melting Ag+-doped TeO2-ZnO-Na2O (TZN) tellurite glass has been demonstrated as an ideal LDW OS medium. Microstructural and spectroscopic studies reveal the generation of molecule-like Agmx+ nanoclusters featured with a broad emission band in the orange-red region upon laser irradiation. Probing the laser-glass interaction yields evidences of the spatial distribution of Ag species responsive to laser-induced thermoelastic pressure wave oscillation, as well as the heat-driven migration/aggregation of Ag species along the radial direction of the laser spot. Raman analyses disclose the loose network of TZN-glass convenient for Ag+ mobility and the increased network connectivity when Agmx+ nanoclusters are precipitated out. Combined with the XPS result of Ag+ → Ag0 reduction, the possible formation mechanism of Ag nanoclusters stabilized in glass has been proposed. In a proof-of-concept experiment, 3D volumetric OS in the TZN glass has been demonstrated, showing optical data encoding/decoding in the form of characters and image patterns.

Thermo-enhanced upconversion luminescence in inert-core/active-shell UCNPs: the inert core matters.

Recent discoveries regarding the anomalous thermo-enhanced luminescence of upconversion nanoparticles (UCNPs) have attracted great interest because of their potentially significant technological importance. Meanwhile, the great debate about the underlying mechanism responsible for this unique luminescence thermal behavior may be equally compelling. To this point, special attention has been paid to the critical interplay between surface species and the energy transfer process (from the sensitizer to the activator) in a thermal field. Herein, inert-core/active-shell UCNPs, in which both the sensitizer and activator are located in the shell area near the nanoparticle surface, have been designed to achieve temperature-dependent upconversion luminescence (UCL) behavior. The results show that the inert-core/active-shell UCNPs exhibit a stronger luminescence thermal enhancement tendency compared to the active-core UCNPs. Specifically, the luminescence thermal enhancement behavior of the inert-core/active-shell UCNPs appears to be core-size dependent, which cannot be explained by either a surface-phonon-assisted mechanism or a surface moisture release mechanism. Based on the relationship between the size-dependent luminescence and size-dependent lattice expansion coefficient, we suggest that the alleviation of the surface quenching induced by lattice thermal expansion is responsible for the presented luminescence thermal behavior of the inert-core/active-shell UCNPs.

All-optical spatial terahertz modulator with surface-textured and passivated silicon.

For a Si-based all-optical spatial terahertz modulator (STM), an enhanced modulation efficiency under low illumination density would be of great significance to exploit the competence of THz technology in real-world applications. We presented here an implementation of such a device by microtexturing and passivating the Si surface, forming a truncated pyramidal array (TPA). This TPA structure with SiO2 passivating coatings not only decreases light reflectance and expands the active area for THz modulation but also remarkably increases the photogenerated carrier lifetime. These 3-fold benefits render Si-TPA superior to bare-Si with respect to the achievable modulation efficiency, especially at low irradiation power. Furthermore such a Si-TPA device is also more applicable than its counterpart that is only passivated by SiO2 nanocoatings, even though the Si-SiO2 has a slightly increased modulation efficiency. These periodically aligned pyramids resembled as a mesa array significantly suppress the lateral diffusion induced by longer diffusion, resulting in an equivalent resolution of bare-Si. This novel Si-TPA based STM is highly desired for realizing a high-performance THz imager and provides a feasible approach to breaking the trade-off between resolution and modulation efficiency.

The influence of distance weight on the inverse distance weighted method for ore-grade estimation.

In order to study the influence of distance weight on ore-grade estimation, the inverse distance weighted (IDW) is used to estimate the Ni grade and MgO grade of serpentinite ore based on a three-dimensional ore body model and related block models. Manhattan distance, Euclidean distance, Chebyshev distance, and multiple forms of the Minkowski distance are used to calculate distance weight of IDW. Results show that using the Minkowski distance for the distance weight calculation is feasible. The law of the estimated results along with the distance weight is given. The study expands the distance weight calculation method in the IDW method, and a new method for improving estimation accuracy is given. Researchers can choose different weight calculation methods according to their needs. In this study, the estimated effect is best when the power of the Minkowski distance is 3 for a 10 m × 10 m × 10 m block model. For a 20 m × 20 m × 20 m block model, the estimated effect is best when the power of the Minkowski distance is 9.

Design and Testing of Inertial System for Landslide Displacement Distribution Measurement.

Landslide displacement monitoring plays a fundamental role in the study of landslide evolution mechanisms, forecasting, risk assessment, prevention, and control. To fill the deficiencies of traditional instrumentation for measuring landslide displacement distributed along lateral direction, a landslide displacement measurement method based on deformation-coupled pipeline trajectory measurement is proposed, and a pipeline trajectory inertial measurement instrument is developed. The developed instrument, primarily comprised of a single shaft gyro, two axis accelerometers, and an external roller encoder, is designed as an axial half strapdown-radial half platform structure combined with a mechanical gravity platform. This structure avoids the singularity of pitch angle and roll angle and can expediently calculate a pipeline trajectory with an Eulerian transformation when obtaining several basic physical variables, e.g., the axial linear velocity, pitch angle, roll angle, and azimuth angle. Additionally, the pipeline trajectory, measured at different times, possesses the ability to reflect the displacement evolution feature of landslides. The results of prototype simulation tests imply a single measurement accuracy of a 12 cm/100 m span and a singly periodic multiple (more than five times) measurement accuracy of a 3 cm/100 m span, which meets medium-precision displacement measurement requirements for a landslide. Additionally, the finished instrument has been successfully applied to the deformation monitoring of the Majiagou I# landslide, which further verifies its feasibility and offers a reference for similar landslides.

A solid-state colorimetric fluorescence Pb2+-sensing scheme: mechanically-driven CsPbBr3 nanocrystallization in glass.

Highly toxic Pb2+ poses a great threat to the health of human beings and ecosystems, urgently calling for an efficient Pb2+ detection method. Herein, we demonstrated a brand-new solid-state fluorescence Pb2+-sensing scheme based on a type of Pb2+-responsive borate glass powder that is able to precipitate CsPbBr3 nanocrystals on the glass surface upon grinding with Pb2+ sources, following a mechanically driven glass crystallization mechanism. Pb2+ sensing is achieved via the Pb2+ concentration-dependent green emission of CsPbBr3 as an indicator signal and independent red emission of Eu3+ as a reference signal. Under UV light irradiation, the obvious emissive color variation from red to green as Pb2+ concentration varies enables the intuitive Pb2+-sensing by naked eyes. With the aid of a spectrometer and smartphone, Pb2+ concentration can be quantitatively determined with the detection limit as low as ∼70 ppm and ∼400 ppm, respectively. The semi-quantitative Pb2+ detection is also possible by comparing the emissive color with the calibrated color card. Hopefully, the proposed solid-state fluorescence Pb2+-sensing strategy with high selectivity can be used for portable and quick Pb2+ analysis in daily life.

High-security-level multi-dimensional optical storage medium: nanostructured glass embedded with LiGa5O8: Mn2+ with photostimulated luminescence.

The launch of the big data era puts forward challenges for information preservation technology, both in storage capacity and security. Herein, a brand new optical storage medium, transparent glass ceramic (TGC) embedded with photostimulated LiGa5O8: Mn2+ nanocrystals, capable of achieving bit-by-bit optical data write-in and read-out in a photon trapping/detrapping mode, is developed. The highly ordered nanostructure enables light-matter interaction with high encoding/decoding resolution and low bit error rate. Importantly, going beyond traditional 2D optical storage, the high transparency of the studied bulk medium makes 3D volumetric optical data storage (ODS) possible, which brings about the merits of expanded storage capacity and improved information security. Demonstration application confirmed the erasable-rewritable 3D storage of binary data and display items in TGC with intensity/wavelength multiplexing. The present work highlights a great leap in photostimulated material for ODS application and hopefully stimulates the development of new multi-dimensional ODS media.

Harvesting Variable-Speed Wind Energy with a Dynamic Multi-Stable Configuration.

To harvest the energy of variable-speed wind, we proposed a dynamic multi-stable configuration composed of a piezoelectric beam and a rectangular plate. At low wind speeds, the system exhibits bi-stability, whereas, at high wind speeds, the system exhibits a dynamic tri-stability, which is beneficial for harvesting variable-speed wind energy. The theoretical analysis was carried out. For validation, the prototype was fabricated, and a piezoelectric material was bonded to the beam. The corresponding experiment was conducted, with the wind speed increasing from 1.5 to 7.5 m/s. The experiment results prove that the proposed harvester could generate a large output over the speed range. The dynamic stability is helpful to maintain snap-through motion for variable-speed wind. In particular, the snap-through motion could reach coherence resonance in a range of wind speed. Thus, the system could keep large output in the environment of variable-speed wind.

[Distribution and Pollution Assessment of Nutrients in the Surface Sediments of a Macrophyte-Dominated Zone in Lake Taihu].

To clarify the spatial distribution and pollution status of nutrients in the surface sediments from a macrophyte-dominated zone in Lake Taihu, total nitrogen (TN), total phosphorus (TP), alkali nitrogen (AN), available phosphorus (AP), and organic matter (OM) were measured at 60 sampling sites in Xukou Bay. A pollution evaluation and source apportionment analysis of these nutrients was also carried out. The average contents of TN, TP, AN, AP, and OM in the surface sediments of Xukou Bay were 1027.5, 423.2, 46.4, 15.3, and 17096.6 mg·kg-1, respectively, with the OM content being significantly higher in the northeast zone than in other areas of the bay. The average value of STN and STP was 1.75 and 0.91, respectively, indicating that TN and TP represent moderate and mild levels of pollution, respectively. The average comprehensive pollution index (FF) was 1.57, indicated that the surface sediment was moderately polluted. The observed organic pollution index indicated that the surface sediments in Xukou Bay were generally clean. Based on C/N values, organic matter in the surface sediments is derived from the bio-deposition of non-fibrous plants and phytoplankton. Based on correlation analysis, OM and TN in the surface sediments of Xukou Bay are derived from the same source, while TP is derived from an alternative source.

Perceiving Linear-Velocity by Multiphoton Upconversion.

Up to now, the rising edge of the upconversion process does not receive due attention. Herein, a demonstration utilizing the feature of the rising edge to practically detect the linear-velocity of an object is presented. Typically, upconversion processes with different numbers of participant photons would exhibit diversity in the rising edge. On this account, when the emitter is moving, the emission intensity ratio of different multiphoton processes will vary with changing linear-velocity, which enables accurate speed detection through spectral analysis. To illustrate this principle, in this work, the modeling and numerical simulation were first performed, and then experimental demonstration was carried out in which core-shell upconversion nanocrystals were elaborately designed and fabricated as the speed sensing probe to calibrate the speed of a homemade turnplate. It is believed that the present work will exploit a novel speed sensing method and find a new application for lanthanide-doped upconversion materials.