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This study presents a design of a 94-GHz high-performance and highly compact frequency-modulated continuous-wave radar sensor. In this sensor, an X-band CMOS-based all-digital phase-locked loop chip, W-band SiGe-based transceiver monolithic microwave integrated circuit (MMIC), and W-band GaN-based MMIC power amplifier (PA) are heterogeneously integrated (HI). Each part of the 130-nm bipolar complementary metal-oxide-semiconductor (BiCMOS) SiGe-based transceiver MMIC is designed to include a low-noise amplifier, PA, octupler, mixer, and lange coupler. The fabrication process of our in-house silicon-based MEMS photosensitive composite film is developed to provide very high-density integration and very low insertion loss of interconnections between chips. The HI front end of the radar sensor is measured on-wafer with a high output power of 22 dBm. Moreover, a low double-sideband noise figure (NF) of 10.2 dB is obtained. Bonding-substrate integrated waveguide (SIW)-WG transitions between the heterogeneously integrated front end and the antenna are specially designed and verified. A 2.3-dB degradation is observed, where 19.7 dBm is measured at the transmitter WG WR-10-flange. Thus, the sensor offers a 55-dB dynamic range at a 2-m position with an expectation of a long-distance target-detection range. The radar sensor has an 11.7-cm range resolution and is only 60 x 40 x 8 mm³ in size, with a weight of only 78 g.

The study of Frequency Selective Surface (FSS) by Direct ink writing (DIW) has attracted much attention due to the convenience and effectiveness of 3D printing technology. However, the limited printing precision of DIW has heavily restricted its applications as the electromagnetic performance is highly sensitive to it, especially the precision at the microscale. Herein, the ultra-high printing precision of FSS was achieved through DIW by the uniformly dispersed graphene sheets to deeply modify the rheological behavior and the steric hindrance effect. Thus, the highly precision of the printed filament width as thin as 67 μm with a space of only 42 μm were achieved, which is difficult for conventional DIW, and no structural distortion is found after 3D printing, no matter it was 2D printed on a flat surface or the sharply skewed hook face, or even 3D printed to architectural structures. According to the highly improved precision, the electromagnetic performance matching between the designed model and the printed physical FSS device was perfectly achieved, reducing the center frequency error less than 0.3 GHz, and the transmission coefficient error less than 0.046. Our work promises an effective and easy preparation of high-quality FSS from the aid of graphene.

Carbon dioxide (CO2) sensing using an optical technique is of great importance in the environment and industrial emission monitoring. However, limited by the poor specific adsorption of gas molecules as well as insufficient coupling efficiency, there is still a long way to go toward realizing a highly sensitive optical CO2 gas sensor. Herein, by combining the advantages of a whispering-gallery-mode microcavity and a metal-organic framework (MOF) film, a porous functional microcavity (PF-MC) was fabricated with the assistance of the atomic layer deposition technique and was applied to CO2 sensing. In this functional composite, the rolled-up microcavity provides the ability to tune the propagation of light waves and the electromagnetic coupling with the surroundings via an evanescent field, while the nanoporous MOF film contributes to the specific adsorption of CO2. The composite demonstrates a high sensitivity of 188 nm RIU-1 (7.4 pm/% with respect to the CO2 concentration) and a low detection limit of ∼5.85 × 10-5 RIU. Furthermore, the PF-MC exhibits great selectivity to CO2 and outstanding reproducibility, which is promising for the next-generation optical gas sensing devices.

Reversible solid oxide cells (RSOCs) have attracted increasing attention due to the potential realizing the deep coupling between hydrogen and electricity. An efficient and stable oxygen electrode is needed for developing RSOCs. Herein, we report a nanostructured hybrid with a nominal composition of BaZr0.2Co0.8O3-δ as oxygen electrode. The chemical composition, crystal structure and physicochemical properties of the BaZr0.2Co0.8O3-δ hybrid have been characterized. The results show that the sintered BaCo0.8Zr0.2O3-δ has grown into a hybrid, consisting of cubic perovskite BaZr0.82Co0.18O3-δ, hexagonal perovskite BaCo0.96Zr0.04O2.6+δ and a small quantity of hexagonal perovskite BaCoO3. The cell with BaZr0.2Co0.8O3-δ hybrid oxygen electrode delivers a current density of 2.09 A cm−2 @0.7 V in SOFC mode, and gives −1.43 A cm−2 @1.3 V in SOEC mode for steam electrolysis. The BaCo0.8Zr0.2O3-δ cell shows a smooth transition from SOEC to SOFC, and gives no obvious degradation after 100 times SOEC↔SOFC cycle operation.

A time-dependent change in the refractive index of a material leads to a change in the frequency of an optical beam passing through that medium. Here, we experimentally demonstrate that this effect-known as adiabatic frequency conversion (AFC)-can be significantly enhanced by a nonlinear epsilon-near-zero-based (ENZ-based) plasmonic metasurface. Specifically, by using a 63-nm-thick metasurface, we demonstrate a large, tunable, and broadband frequency shift of up to ∼11.2 THz with a pump intensity of 4 GW/cm2. Our results represent a decrease of ∼10 times in device thickness and 120 times in pump peak intensity compared with the cases of bare, thicker ENZ materials for the similar amount of frequency shift. Our findings might potentially provide insights for designing efficient time-varying metasurfaces for the manipulation of ultrafast pulses.

Hydrogen production via solid oxide electrolysis cell (SOEC) is world widely concerned with the new energy revolution. The SOEC performance must be enhanced for the practical application. In this study we report a high-performance Ce0.9Co0.1O2-δ-LSM-YSZ (CC-LSM-YSZ) oxygen electrode, in which Ce0.9Co0.1O2-δ nanoparticles are loaded on LSM-YSZ scaffold and characterized by XRD, SEM, O2-TPD and H2-TPR. Under 50% absolute humidity (A.H), the cell with 1CC-LSM-YSZ, 2CC-LSM-YSZ, 3CC-LSM-YSZ and 4CC-LSM-YSZ oxygen electrode delivers a current density of 0.63, 0.94, 1.14 and 1.26A cm−2 at 1.3 V, which is 1.7, 2.5, 3.0 and 3.3 times higher than the blank LSM-YSZ cell, respectively. The hydrogen generation rate of the 4CC-LSM-YSZ cell is as high as 873 m L cm−2 h−1 under 70% A.H. The DRT results demonstrate the accelerated charge transfer reaction on LSM-YSZ-Ce0.9Co0.1O2-δ oxygen electrode. LSM-YSZ-Ce0.9Co0.1O2-δ has the potential for the application of oxygen electrode in SOEC technology.

In this study, four types of triply periodic minimal surface (TPMS) were implemented to create cellular ceramics via digital light processing (DLP) technology, namely p-cell, gyroid, IWP and s14. The mechanical properties of these TPMS structures were investigated experimentally. Results showed that compressive strength of TPMS structures increases with relative density. IWP and s14 structures exhibit similar mechanical response under stress. In general, all TPMS structures can sustain >2% strain without failure and the compressive strength followed the order of s14 > IWP > gyroid > p-cell. The s14 structure can reach a high compressive strength of 105 MPa at a structural density of 30.5 % while gyroid structure can provide a compressive strength of 5.6 MPa at a very low structural density of 6.7 %. The porosity dependence of Young’s modulus of sintered zirconia TPMS demonstrated that the Pabst-Gregorova exponential relation can provide a better prediction than the classical Gibson-Ashby model.

High performance hydroxyapatite (HA) ceramics with excellent densification and mechanical properties were successfully fabricated by digital light processing (DLP) three-dimensional (3D) printing technology. It was found that the sintering atmosphere of wet CO2 can dramatically improve the densification process and thus lead to better mechanical properties. HA ceramics with a relative density of 97.12% and a three-point bending strength of 92.4 MPa can be achieved at a sintering temperature of 1300 , which makes a solid foundation for application ℃ in bone engineering. Furthermore, a relatively high compressive strength of 4.09 MPa can be also achieved for a DLP-printed p-cell triply periodic minimum surface (TPMS) structure with a porosity of 74%, which meets the requirement of cancellous bone substitutes. A further cell proliferation test demonstrated that the sintering atmosphere of wet CO2 led to improve cell vitality after 7 days of cell culture Moreover, with the possible benefit from the bio-inspired structure, the 3D-printed TPMS structure significantly improved the cell vitality, which is crucial for early osteogenesis and osteointegration.

Silica nanoparticle coating on quartz optical fiber facilitates side-emission of germicidal ultraviolet light (UV-C), which shows promise for disinfection of contaminated air, water, and surfaces. However, the emitted light along the length of optical fibers decreases exponentially with distance from the LED light source, which makes designing applications more challenging and reduces overall useable length of optical fiber to disinfect water or surfaces. This work aims to develop an understanding of light interactions with the silica nanoparticles to allow more uniform side-emission of germicidal light along longer lengths of optical fibers. Two forms of light energy (refracted light and evanescent waves) are transmitted through optical fibers. The amount of side-emitted UV-C light is overwhelmingly controlled by the evanescent wave energy interacting with nanoparticles at distances from 30 cm). The fundamental insights and experimental validation into light interactions with nanoparticles on SEOF surfaces, in conjunction with prior bacterial inactivation studies, enables use of UV-C light produced by light emitting diodes (LEDs) to mitigate biofilm formation on confined surfaces commonly found in water treatment, premise plumbing, and cooling systems.

We have developed a miniature two-photon microscope equipped with an axial scanning mechanism and a long-working-distance miniature objective to enable multi-plane imaging over a volume of 420 × 420 × 180 μm3 at a lateral resolution of ~1 μm. Together with the detachable design that permits long-term recurring imaging, our miniature two-photon microscope can help decipher neuronal mechanisms in freely behaving animals. A two-photon miniature microscope with enlarged field of view and axial scanning capabilities has been developed and applied in freely moving mice.

Objective To evaluate the strain‐rate‐dependent viscoelastic properties of the intervertebral disc by in vitro experiments. Method The biomechanical experiments were conducted from September 2019 to December 2019. The lumbar spines of sheep were purchased within 4–6 hours from the local slaughterhouse, and the intervertebral disc samples were divided into three groups. In rupture group, the samples were used to test the mechanical behavior of the intervertebral disc rupture at different strain rates. In fatigue injury group, the samples were used to test the mechanical behavior of fatigue injury on the intervertebral disc under different strain rates. In internal displacement group, the samples were used to test the internal displacement distribution of the intervertebral disc at different strain rates by applying an optimized digital image correlation (DIC) technique. Results Both the yielding and cracking phenomenon occurs at fast and medium loading rates, while only the yielding phenomenon occurs at a slow loading rate. The yield stress, compressive strength, and elastic modulus all increase with the increase of the strain rate, while the yield strain decreases with the increase of the strain rate. The logarithm of the elastic modulus in the intervertebral disc is approximately linear with the logarithm of the strain rate under different strain rates. Both before and after fatigue loading, the stiffness in the loading and unloading curves of the intervertebral disc is inconsistent, forming a hysteresis loop, which is caused by the viscoelastic effect. The strain rate has no significant effect on the internal displacement distribution of the intervertebral disc. Based on the experimental data, the constitutive relationship of the intervertebral disc at different strain rates is obtained. The fitting curves are well coupled with the experimental data, while the fitting parameters are approximately linear with the logarithm of the strain rate. Conclusions These experiments indicate that the strain rate has a significant effect on the mechanical behavior of the intervertebral disc rupture and fatigue injury, while the constitutive equation can predict the rate‐dependent mechanical behavior of lumbar intervertebral disc under flexion very well. These results have important theoretical guiding significance for preventing lumbar disc herniation in daily life., These experiments indicate that the strain rate has a significant effect on the mechanical behavior of the intervertebral disc rupture and fatigue injury, while the constitutive equation can predict the rate‐dependent mechanical behavior of lumbar intervertebral disc under flexion. These results have important theoretical guiding significance for preventing disc herniation

Atomic layer deposition (ALD) is an effective technique of preparing nanomembranes with atomic scaling precision, high uniformity, superior conformality, and excellent accessibility on different su...

Self-assembly is an emerging strategy for preparing composite cathodes with good oxygen electrochemical reduction activity and congenital chemical compatibility for intermediate-temperature solid oxide fuel cell (IT-SOFC). Here we report that a self-assembled BaCo0.6Zr0.4O3-δ (BZC-BC) nanocomposite is prepared through one-pot glycine-nitrate process and exhibits high cathode performance. The BZC-BC nanocomposite is composed of 62 mol% cubic perovskite BaZr0.82Co0.18O3-δ (BZC) as an ionic conductor and 38 mol% hexagonal perovskite BaCo0.96Zr0.04O2.6+δ (12H-BC) as a mixed ionic and electronic conductor. The BZC-BC nanocomposite has the pomegranate-like particles aggregated with a larger number of nanoparticles (50-100 nm) which greatly enlarge the three-phase boundary sites. The BZC-BC nanocomposite exhibits a thermal expansion coefficient of 12.89 × 10−6 K−1 well-matched with that of Ce0.8Gd0.2O3-δ (12.84 × 10−6 K−1) electrolyte. The high electro-catalytic activity of BZC-BC nanocomposite cathode for oxygen reduction is reflected by the low polarization resistances of oxygen ions incorporation at cathode/electrolyte interface (0.02823 Ω cm2), oxygen species diffusion (0.03702 Ω cm2) and oxygen adsorptive dissociation (0.07609 Ω cm2) at 700 °C. The single cell with BZC-BC nanocomposite cathode achieves the maximum power density of 1094 mW cm−2 at 650 °C and shows good stability under 25 h run.

The development of photosensitive slurries for additive manufacturing has attracted great interest due to their correlation with the final properties of the fabricated parts. This paper focus on the printing quality control in digital light processing (DLP) 3D printing of advanced ceramics. Systematic experiments were performed to assess the effects of the exposure time and printing angle on the three-point bending strength of the fabricated samples. The exposure time affected the bending strength of the printed zirconia ceramic dramatically. When the weak exposure time is 1 s and the strong exposure time is 13 s, the average bending strength can reach 580 MPa while Weibull modulus can reach 8.84. Meanwhile, the printing angle also affected the bending strength mechanical sample printed at 45° exhibits the worst performance.

Cyclone separator, used as the biogas pretreatment equipment, was taken as the research object in this study. In order to improve the separation rate of biogas impurity particles, the influence of ...

The product could not be effectively expanded and the puffing temperature was too high, which usually occurred during the explosion puffing drying process of fruits and vegetables. CO2 high-pressur...

In this work, 8mol% yttria-stabilized zirconia (8YSZ) ripple-shaped electrolytes have been prepared by digital light processing (DLP) 3D printing and their electrochemical performances have been investigated. The total conductivities of flat samples printed at different angles were tested firstly to confirm that there is no huge influence on the electrochemical performance from the printing itself. Then, by using ripple-shaped electrolytes, primary cells were assembled and their electrochemical performance were investigated. Compared with the reference flat cell, an improvement of ~32% was achieved in the power density for the same thickness of the electrolyte (~200 µm) at 800 °C.

Solid Oxide Fuel Cells (SOFCs) are environmentally efficient energy conversion devices, but are partially limited by the complicated fabrication procedure. In this work, dense 8 mol% yttria-stabilized zirconia (8YSZ) ceramics were successfully realized through a DLP (digital light processing) stereolithography method and the electrolyte self-supported fuel cell was also tested at 800 °C. The sintering behavior of the as-printed planar samples were investigated and a fully dense ceramic can be achieved at 1450 °C. The total conductivity of the sintered 8YSZ can reach 2.18 × 10−2 S cm−1 at a test temperature of 800 °C, which is acceptable for practical application. For the electrolyte self-supported fuel cell test, a power density of 114.3 mW cm−2 can be achieved when Ni-8YSZ cermet and La0.8Sr0.2MnO3 (LSM) were used as anode and cathode. It was demonstrated that 3D printing is a promising processing technique to build up electrolyte self-supported SOFCs with desired structure for the future development.

This article presents a comprehensive design and validation of a compact all-silicon carbide (SiC) 250-kW T-type traction inverter with a power density of 25 kW/l and 98.5% peak efficiency. All the operation modes and switching transitions in a T-type phase leg are analyzed to model the semiconductor power losses over a fundamental cycle. Special attention has been paid to investigate the behavior and losses due to the reverse conduction of the SiC MOSFETs. Then a loss model is built based upon this analysis to calculate the device loss distribution and system efficiency, which is further used to determine the optimal switching frequency. In addition, detailed inverter system design and prototyping procedure, including the selection of SiC modules and dc-link capacitors, and the optimization of a four-layer laminated busbar, are presented. In this article, the T-type phase leg is formed by a normal half-bridge module and a common-source module. The switching performance and losses in this configuration are different from two-level topology that only uses one SiC module. Therefore, the switching performance and the associated switching energy in each switch position are characterized using a custom clamped inductive load (CIL) test setup designed for a T-type phase leg. The performance of the full power traction inverter prototype has been verified experimentally using pulse testing and continuous power testing.

The atomic layer deposition (ALD) technique has been widely employed in the development of efficient electrochemical hydrogen evolution reaction (HER) catalysts. Nevertheless, most of the studies through this methodology are confined to the use of precious metals or non-precious materials with poor performance, especially in alkaline electrolytes. Herein, we report a novel strategy of fabricating nickel nanograins coated onto a Co, N-doped carbon framework (Co-NCF@Ni) based on the manipulation of ALD and in situ transformation of a cobalt zeolitic imidazolate framework for efficient hydrogen evolution in alkaline media. The catalytic performance of the Co-NCF@Ni with different Ni contents is specifically studied. On the basis of this composite, a flexible high-performance H2 production device, distinguished from the conventional powdery pattern, is realized, and stable performance under a repeated rolling process is demonstrated. In order to disclose the mechanism of the remarkable HER performance, density functional theory calculations are carried out and the results indicate that the electron structures of inner Co atoms, external Ni atoms, and the N-doped carbon layer can be tuned due to the introduction of Ni nanoparticles. The research presented here may have great potential in developing both high efficiency transition-metal based electrocatalysts and flexible H2-production devices for use under extreme conditions.

A numerical study on effects of hydrogen direct injection on hydrogen mixture distribution, combustion and emissions was presented for a gasoline/hydrogen SI engine. Under lean burn conditions, five different direct hydrogen injection timings were applied at low speeds and low loads on SI engines with direct hydrogen injection (HDI) and gasoline port injection. The results were showed as following: firstly, with the increase of hydrogen direct injection timing, the hydrogen concentration near the sparking plug first increases and then decreases, reaching the highest when hydrogen direct injection timing is 120°CA BTDC: Secondly, hydrogen can speed up the combustion rate. The main factor affecting the combustion rate and efficiency is the hydrogen concentration near the sparking plug: Thirdly, in comparing with gasoline, the NOX emissions with hydrogen addition increase by an average of 115%. For different hydrogen direct injection timings, the NOX emissions of 120°CA BTDC is the highest, which is 29.9% higher than the 75°CA BTDC. The hydrogen addition make the NOX emissions increase in two ways. On the one hand, the average temperature with hydrogen addition is higher. On the other hand, the temperature with hydrogen addition is not homogeneous, which makes the peak of temperature much higher. In a word, the main factor of NOX emissions is the size of high temperature zone in the cylinder: Finally, because the combustion is more complete, in comparing with gasoline, hydrogen addition can reduce the CO and HC emissions by 32.2% and 80.4% respectively. Since a more homogeneous hydrogen mixture distribution can influence a lager zone in the cylinder and reduce the wall quenching distance, these emissions decrease with the increase of hydrogen direct injection timing. The CO and HC emissions of 135°CA BTDC decrease by 41.5% and 71.4%, respectively, compared to 75°CA BTDC.

Electrochemical conversion with solid oxide electrolysis cells is a promising technology for CO2 utilization and simultaneously store renewable energy. In this work, Ce0.9M0.1O2−δ (CeM, M=Fe, Co, Ni) catalysts are infiltrated into La0.6Sr0.4Cr0.5Fe0.5O3−δ–Gd0.2Ce0.8O2−δ (LSCrFe-GDC) cathode to enhance the electrochemical performance for CO2 electrolysis. CeCo-LSCrFe-GDC cell obtains the best performance with a current density of 0.652 A cm−2, followed by CeFe-LSCrFe-GDC and CeNi-LSCrFe-GDC cells with the value of 0.603 and 0.535 A cm−2, respectively, about 2.44, 2.26 and 2.01 times higher than that of the LSCrFe-GDC cell at 1.5 V and 800 °C. Electrochemical impedance spectra combined with distributions of relaxed times analysis shows that both CO2 adsorption process and the dissociation of CO2 at triple phase boundaries are accelerated by CeM catalysts, while the latter is the key rate-determining step.

Smart cloth, as well as smart fibers, exhibits promising prospects in wearable electronics applications. However, very few kinds of smart fibers can be applied in the biomedical-related area, and the high cost and the poor adhesion between the functional layer and textile substrate remain challenging. Here, we present an efficient strategy utilizing atomic layer deposition pretreatment to induce the growth of hydroxy double salt (HDS) nanosheets on carbon fibers, and the HDS nanosheets are then chemically converted into a zeolitic imidazolate framework-67 layer, which closely attaches to the carbon fibers, forming composite Co-containing porous smart fibers (Co-PSF). On these smart fibers, a three-dimensional (3D) functional film is assembled and intimately adheres to the surface of the fibers, forming a hierarchical nanostructure with an enhanced surface area. The corresponding increased exposure of active sites and the improved electron transfer in the composite lead to improved efficiency of the electrochemical reaction and result in excellent glucose sensing in terms of good anti-interference ability, fast response, and an ultrahigh sensitivity of 4835 μA mM−1 cm−2. Furthermore, the smart textile derived from Co-PSF shows good flexibility and stable electrochemical performance under 100 cycles of 180° bending.

Inspired by an electromagnetic hydropower station that contains a reverse polarized magnet, we proposed a new design methodology of electret rotatory energy harvester (e-REH) with bipolar-charged electrets for boosting its output performance. A selectively localized corona discharging method is invented to have both positive and negative ultra-high-resolution charges implanted into a single electret thin film. A generalized theoretical model of bipolar-charged e-REHs with free-standing (Fe-REH) and sliding (Se-REH) operation modes is derived to evaluate their performance. The key features affecting their performance are the initial and parasitic capacitances with different connection schemes. Experimental results show that: the output power of the bipolar-charged e-REH is increased to 392.2% compared to those of the positive alone and negative alone configurations, which fully agree with those obtained from the theoretical model. For the first time, an intelligent thrust ball bearing is designed and fabricated with its self-powered and self-sensing capabilities based on the bipolar-charged e-REH. The rotation speed of the bearing is characterized by the response frequencies of the output voltage by Fast Fourier Transform instead of the output voltage amplitudes, exhibiting an ultra-high frequency sensitivity of 15.0 rpm/Hz and a good linearity R2 (coefficient of determination) of 99.9%. The developed e-REH has potential applications for high-precision and self-powered intelligent rotation-speed sensing

Ionic conductivity enables the technologies of fuel cells, electrolysis cells, and batteries. However, the ambiguous origins of the extraordinary ionic conductivity impede its implementation in heterostructure films for the devices. Here, we disclosed that the extraordinary ionic and electronic conductivities come from field effect. We found in Ce0.8Gd0.2O2-δ (CGO)/Zr0.85Y0.15O2-δ (YSZ) heterostructures that the ionic conductivity of CGO layer (n-i conductor) and the electronic conductivity of YSZ layer (p-i conductor) exponentially increased with potential. The potential occurred from electron transfer and stoichiometric polarization in p-i-n junction. Field effect ionic conductivity contributed the major increment in the maximum power density. The results demonstrated field effect ionic and electronic conductivities, their dependences on heterostructures, and impacts on fuel cells.

A CO2-responsive composite of multiwall carbon nanotube (MWCNT) coated with polydopamine (PDA) and polydimethylamino-ethyl methacrylate (PDMAEMA) was prepared. The PDA was first self-polymerized on the surface of carbon nanotube. 2-bromoisobutyryl bromide (BiBB) was then immobilized by PDA and then initiated the ATRP of DMAEMA on the carbon nanotube surface. The resulting composite was characterized by Fourier-transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The CO2-responsive test was performed by bubbling CO2 into the mixture of MWCNT-PDA-PDMAEMA composite in water. A well-dispersed solution was obtained and the UV-Vis transmittance decreased dramatically. This is attributed to the reaction between PDMAEMA and CO2. The formation of ammonium bicarbonates on the surface of carbon nanotubes leads to the separation of nanotube bundles. This process can be reversed as the removal of CO2 by bubbling N2.

This paper presents a novel micro electret power generator as self-powered railway sensor for both horizontal oscillation detection and rotation speed monitoring. Both the electret material and counter electrode are micro-patterned with square-shaped blocks and connected diagonally. By this way, capacitance variation can be maximized in either horizontal oscillation or axial rotation. From the experiment results, they show obvious differences between the waveforms from two types of motions. Therefore, both the rotation of the iron wheel and the change of the track in railway can be precisely detected and distinguished. The experimental results show that the peak value of the output voltage can reach 121.94 V when the rotation speed is 600 rpm in the rotating mode and 132.96 V in the sliding mode. The self-powered sensing system can not only achieve stable and continuous output signals, but also adapt to the multi-directional working environment. The outcomes of this work offer new insights of realizing single structured electret power generator for multifunctional applications.

In this work, a 25 kW all silicon carbide (SiC) series-resonant converter (SRC) design is proposed to enable a single stage dc to dc conversion from 3kV to 540V (±270V) for future electric aircraft applications. The proposed SRC consists of a 3-level neutral-point-clamped (NPC) converter using 3.3kV discrete SiC MOSFETs on the primary side, a H-bridge converter using 900V SiC MOSFET modules on the secondary side and a high frequency (HF) transformer. The detailed design methods for the SRC power stage and the HF transformer are presented. Especially, a tradeoff between the complexity for the cooling system and the need for power density is addressed in the transformer design, leading to a novel multi-layer winding layout. To validate the effectiveness of the proposed SRC design, a converter prototype has been developed and comprehensive experimental studies are performed.

Summary It is challenging to realize high efficiency and stability in perovskite photovoltaics simultaneously. Here, we show supramolecular chemistry using macrocyclic crown ether to prepare high-performance metal-halide perovskite films. Multiple cooperative supramolecular interactions between perovskites and crown ether are built, and superior defect passivation is achieved. A thin crystalline capping layer on top of perovskites is constructed to synergistically passivate the perovskite surface defects and protect the underlying films from environmental damage. The capping layer is confirmed to be a unique two-dimensional (2D) crystal with a highly ordered, high-crystallinity lamellae structure and face-sharing lead-halide octahedral organization, providing surface protection on the perovskite matrix. Lead-halide perovskite solar cells (PSCs) with supramolecular passivation and a 2D crystal interlayer demonstrated remarkable photovoltaic efficiency and stability improvements, offering a 21.5% efficiency and improved environmental stabilities under moisture, ultraviolet (UV) irradiation, and thermal stress. Our work provides a strategy to achieve efficient and stable lead-halide perovskite-based devices by crown ether-induced supramolecular passivation and 2D crystal interlayer protection.

Nanostructures are considered to have great potential and are widely used in energy storage and sensing devices, and atomic layer deposition (ALD) is of great help for better nanostructure fabrications. ALD can help to preserve the original properties of materials, and, meanwhile, the excellent film quality, nanoscale precise thickness control, and high conformality also play important role in fabrication process. To enhance the performance of energy storage and sensor devices, ALD has been used in directly fabricating active nanostructures, depositing protective passivation layers, etc. ALD is a convenient technique which has been widely engaged in energy-related fields including electrochemical conversion and storage, as well as in sensor and biosensors. The related research interest is increasing significantly. In this review, we summarize some of the latest works on ALD for batteries, supercapacitors, and sensors, and demonstrate the benefits of ALD comprehensively. In these devices, different materials are deposited by ALD under different conditions to achieve better battery performance, higher supercapacitor capacitance, and higher sensitivity. This review fully presents the strengths of ALD and its application in energy storage and sensing devices and proposes the future prospects for this rapidly developing technology.

To enhance the detection precision of samples with scattering characteristics by near infrared spectroscopy (NIRS), this study developed a heteromorphic sample pool and established the related 2D light intensity acquisition system, which can simultaneously acquire multi-path exit light adsorption and scattering information of the samples under test. The Intralipid-20% phantom solutions in 34 samples with different concentrations were detected, while one-dimensional (1D) exit light intensity distributions and two-dimensional (2D) exit light intensity distributions on the surface of the samples were analyzed and modeled using partial least squares. In contrast with the prediction results based on the modeling method of 1D exit light intensity distribution, the modeling method of 2D exit light intensity distribution exhibits more favorable results; specifically, correlation coefficient enhanced by 2.48%, while root mean square error reduced by 6.89%. The experimental results demonstrate that using heteromorphic sample pool can effectively achieve NIRS-based detection precision and speed of chemical components in the solutions with scattering characteristics, which can provide important references for high-throughput and high-precision detection of turbid media in analytical chemistry.

For measuring the optical parameters of biological tissues accurately and rapidly, this study built an optical parameters measurement system based on near-infrared (NIR) Diffuse Photon Density Waves (DPDW) technology using frequency sweep modulation. The transmitted swept optical amplitude and phase can be nonlinearly fitted according to the physical diffusive approximation equation then to obtain the absorption coefficient and reduced scattering coefficient of the tissue phantoms, respectively. The experimental results of the 20 Intralipid solutions show that the average absolute errors of μ a and μ s ′ are 0.066 cm−1 and 0.716 cm−1, respectively, and the correlation coefficients between the measured and true values were 0.965 and 0.989, respectively. The experimental results of the 3 solid phantoms show that the average absolute errors of μ a and μ s ′ are 0.1140 cm−1 and 0.0023 cm−1, respectively. Therefore, the DPDW technology with frequency sweep modulation can detect the optical parameters of the tissue phantoms accurately and quickly, and it would be optimized for tissue tomography imaging and blood components noninvasively detection in vivo.

A series of doped perovskite AxSr1−xFeO3−δ (A = Pr, Sm; 0 ≤ x ≤ 0.8) nanoparticles were synthesized using a solution combustion method. By doping lanthanide elements, the crystal phase of the perovskite SrFeO3−δ (SFO) changed from cubic to orthorhombic system. Phase transitions and mixed-phase components of prepared catalysts can be successfully controlled only by varying the mole ratio of A-site doping at 800 °C for 5 h. Compared with pure SFO, the Pr/Sm-doped SFO samples exhibited enhanced absorption capability especially in the visible light region. The band gap of Pr/Sm-doped SFO samples was gradually decreased and the BET surface area increased with the increase of the Pr and Sm dopant content. The perovskite AxSr1−xFeO3−δ (A = Pr, Sm; x = 0.6, 0.8) included mixed phases of cubic and orthorhombic crystallinity and exhibited better photocatalytic degradation of rhodamine B (RhB) than single cubic phase. The photodegradation efficiency of RhB was increased with an increasing amount of A-site doping.

This paper proposes an electrostatic-piezoelectric hybrid vibrational power generator with different frequency broadening schemes. Both the nonlinear frequency broadening mechanisms and the synergized effect of the electrostatic-piezoelectric hybrid structures are investigated. On the one hand, we adopt the curved fixture structure, which has a 25% increase in bandwidth compared with the ordinary stopper structure. On the other hand, by integrating the electrostatic structure, the half-power bandwidth of the piezoelectric cantilever beam is 16Hz to 20Hz, and the peak power is 3.6mW, the half-power bandwidth of the electrostatic structure is 14.5Hz to 19.5Hz, and the peak power is 2.2mW. This means that under the same space utilization, the performance is improved by 60%. In this paper, the hybrid generator's structure and performance are optimized, and finally the response bandwidth and performance are improved. In general, the device designed in this paper has advantages such as larger bandwidth and better performance.

This paper reports novel binder-free and self-supported electrodes of hierarchical nickel–cobalt phosphide (NiCoP) films decorated with size-controlled Ag quantum dots by magnetron sputtering (Ag/NiCoP). Ag quantum dots with an average particle size of 7.90 nm uniformly distribute over the nanosheet-assembled architecture of NiCoP films. Benefitting from the good ohmic contact in the interfaces between Ag quantum dots and NiCoP nanosheets, Ag/NiCoP exhibits an ultrahigh specific capacitance of 6150 mF cm−2 (3050 F g−1 at 1 A g−1) higher than the 3445 mF cm−2 (1722 F g−1 at 1 A g−1) of bare NiCoP at 2 mA cm−2. The specific areal capacitance has been increased by 78.5% after introducing Ag quantum dots. 34% capacitance retention rate is achieved while the current density increases from 2 to 30 mA cm−2. The cycling stability displays a remarkable capacitance retention of 73% for 4000 cycles at 30 mA cm−2. These boosted electrochemical performances are mainly attributed to the synergistic effects of enough electroactive sites, high electronic conductivity, and easy electrolyte ion diffusion. An asymmetric supercapacitor is fabricated using hierarchical Ag/NiCoP as the positive electrode and activated carbon as the negative electrode. The supercapacitor delivers an energy density of 0.254 mW h cm−2 (1.81 mW h cm−3) at a power density of 1.88 mW cm−2 (13.4 mW cm−3). At a power density of 18.8 mW cm−2 (134 mW cm−3), an energy density of 0.115 mW h cm−2 (0.82 mW h cm−3) can still be maintained. This study provides an avenue to design a novel generation of supercapacitors for energy storage devices.

Inspired by an electromagnetic hydropower station that contains reverse polarized magnets, this paper reports a multi-phase bipolar rotary electret power generator (MB-RPH) with a DC output current. It is capable of generating an almost constant current output with a low crest factor by phase coupling caused by multi-phase structure and integrating both positive and negative charged electret into monolayer rotary power generators by bipolar charging to improve output performance. Experiments show that the output power of each phase is increased to about 367% by bipolar charging ' the output performance significantly increases as the phase increase and the crest factor of current substantially decreases as the phases increase. The MB-RPG with three-phase produces an output voltage of 163.5 V, output current 4.3 µA at 600 rpm and an average output power of 1.05 mW. The MB-RPG not only has high-performance output but also realizes an almost constant DC output, which is of considerable significance to the practical application of sensor energy supply.

Large defect-free domains of a hexagonal packed monolayer of silica spheres with the size of 4000 &micro, m2 were successfully prepared by dual-speed spin coating. Experimental design and statistical analysis instead of the traditional &lsquo, changing one separate factor at a time&rsquo, (COST) approach were employed to guide the implementation of the experiments. With its assistance, the hexagonal-close-packed (HCP) percentage was elevated to 84% in this study. Furthermore, almost all the samples with parameters in the selected ranges possessed more than a 60% HCP percentage. In addition, the optimal values for parameters of the suspension concentration, the first rotation speed, and the spinning time to obtain well-ordered silica spheres arrays were also identified as 30 wt.%, 1000 rpm and 20 s, respectively.

The active layer morphology transition of organic photovoltaics under non-equilibrium conditions are of vital importance in determining the device power conversion efficiency and stability; however, a general and unified picture on this issue has not been well addressed. Using combined in situ and ex situ morphology characterizations, morphological parameters relating to kinetics and thermodynamics of morphology evolution are extracted and studied in model systems under thermal annealing. The coupling and competition of crystallization and demixing are found to be critical in morphology evolution, phase purification and interfacial orientation. A unified model summarizing different phase diagrams and all possible kinetic routes is proposed. The current observations address the fundamental issues underlying the formation of the complex multi-length scale morphology in bulk heterojunction blends and provide useful morphology optimization guidelines for processing devices with higher efficiency and stability., Designing efficient blue perovskite LEDs by using mixed halides perovskite is still a challenge, limited mainly by the phase segregation issue. Here, the authors demonstrate in situ fabrication of quasi-2D CsPbClBr2 nanocrystal films with mixed ligands to overcome the constraint.

The chemical structure of donors and acceptors limit the power conversion efficiencies achievable with active layers of binary donor-acceptor mixtures. Here, using quaternary blends, double cascading energy level alignment in bulk heterojunction organic photovoltaic active layers are realized, enabling efficient carrier splitting and transport. Numerous avenues to optimize light absorption, carrier transport, and charge-transfer state energy levels are opened by the chemical constitution of the components. Record-breaking PCEs of 18.07% are achieved where, by electronic structure and morphology optimization, simultaneous improvements of the open-circuit voltage, short-circuit current and fill factor occur. The donor and acceptor chemical structures afford control over electronic structure and charge-transfer state energy levels, enabling manipulation of hole-transfer rates, carrier transport, and non-radiative recombination losses., Efficiency of organic solar cells is determined by the physical properties of donors and acceptors in bulk heterojunction film. The authors optimise quaternary blends to realize a double cascading energy level alignment enabling efficient carrier dissociation and transport, achieving 18% efficiency.

In recent years, atomic layer deposition (ALD) is widely used for surface modification of materials to improve the catalytic performance for removing pollutants, e.g., CO, hydrocarbons, heavy metal ions, and organic pollutants, and much progress has been achieved. In this review, we summarize the recent development of ALD applications in environmental remediation from the perspective of surface modification approaches, including conformal coating, uniform particle deposition, and area-selective deposition. Through the ALD conformal coating, the activity of photocatalysts improved. Uniform particle deposition is used to prepare nanostructured catalysts via ALD for removal of air pollutions and dyes. Area-selective deposition is adopted to cover the specific defects on the surface of materials and synthesize bimetallic catalysts to remove CO and other contaminations. In addition, the design strategy of catalysts and shortcomings of current studies are discussed in each section. At last, this review points out some potential research trends and comes up with a few routes to further improve the performance of catalysts via ALD surface modification and deeper investigate the ALD reaction mechanisms.

We experimentally demonstrate adiabatic wavelength conversion using a time-varying epsilon-near-zero-based metasurface. We observe up to 47-mn redshift with 4-GW/cnr pump peak intensity. The wavelength shift depends on both pump-probe delay time and pmnp peak intensity.

Weak interactions, non-uniformity and powdery assemblies limit the wide application of metal organic framework (MOF) in devices. Here we report a new strategy for area-selective assembly of MOF particles to prepare a thin film with the assistance of atomic layer deposition (ALD). Self-assembled hierarchically porous Fe-based MOF (PCN-333) films were formed on both flat and complex three-dimensional (3D) substrates by combining gas and liquid fabrication approaches, and can be precisely patterned with photolithography. We demonstrate that the PCN-333 film obtained possesses excellent electrochemical activity and can be applied in dopamine sensing for ultra-high sensitivity of 4637.78 µA mM−1 cm−2 with a wide linear range and a low limit of detection. Moreover, the PCN-333 film composite achieves a function of good selectivity of distinguishing dopamine and ascorbic acid. This strategy is promising to prepare MOF film-based on-chip devices with advanced functions.

Hierarchical and binder-free electrode materials with large electroactive sites and low contact resistance are benefit for electrochemical capacitors. Herein, this paper reports the binder-free and hierarchical ZnCo2O4 arrays decorated with carbon dots (CDs/ZnCo2O4) on nickel foam by hydrothermal route. The CDs/ZnCo2O4 arrays exhibit the nanowires-assembled hierarchical grass-like structure. The outward directed nanowires yield high surface-to-volume ratio. The nanowires exhibit the average length of 1 μm and diameter of 50 nm. The specific capacitance of the CDs/ZnCo2O4 can reach 1937 F/g higher than the 1192 F/g of bare ZnCo2O4 at 1 A/g. And 78.5% capacitance retention rate is achieved while the current density increases from 0.5 to 8 A/g. 90% of the capacitance retention over 5000 charge-discharge cycles at 15 A/g indicates high cycling stability. These boosted electrochemical performances are attributed to the structural feature with exposed electroactive sites, high electrical conductivity assisted by CDs, and opened interspaces for electrolyte ion diffusion. Asymmetric two-electrode system assembled with CDs/ZnCo2O4 and activated carbon delivers a high-energy density of 54.94 W h/kg at 425.3 W/kg and retains an energy density of 13.23 W h/kg at 6804 W/kg. This study provides a new approach to design high-performance electrode materials for supercapacitors.

Ethanol is a widely used alternative fuel for sustainable development, showing potential for improving the combustion and emission characteristics. Both EGR and lean burn are important technical approaches for engines to reduce emissions In this paper, the performance EDI + GPI four-cylinder spark ignition engine at three access air ratios, five ethanol direct injection ratios and five exhaust recirculation ratios was studied at the speed of 1500rmp. The results show that, the cooperation of EDI and EGR can improve the engine performance. Under lean burn conditions, When 6%EGR+45%EDIr, CA 0-10 decreases 49. 8%. When 12%EGR+30%EDIr, BMEP increases 6. 59%, HC decreases 28.33%, total particle number decreases 93.87%. When 6%EGR+30%EDIr, Pmax increases 26.58%, crank angle corresponding to Pmax decreases 41.98%. And in this condition, CoVIMEP is only 1.46%, decreased 21.51% from the original engine. With the increase of λ, EGR limit of CO moves from 12% to 6%; the optimal ethanol direct injection ratio of CO moves from 30% to 15%. NOx decreases about 136.08 ppm with an average increase of 1% EGR. In summary, ethanol has a higher oxygen content and laminar flame speed is faster. EGR can not only reduce pumping losses and throttling losses, but also effectively accelerate the positive effects of ethanol on combustion and emissions. EGR + EDI + GPI can obviously increase the engine power performance, improve fuel economy and decline the emissions. When the engine speed = 1500 rpm, 12%EGR+30%EDIr is the optimal combination of SI engine at λ = 1.2.