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Active damping strategies are commonly used for grid current harmonic suppression in electrolytic capacitorless motor drives. However, they lead to the increase of motor harmonics. In this letter, a multiport-impedance-optimization-based harmonic suppression strategy is proposed, which considers both grid current and motor current harmonics. A multiport impedance model is constructed, in which the rectifier voltage is served as the input, while motor current and dc-link current serve as outputs. Moreover, the impedance optimization index that quantifies harmonic content on the motor and grid sides is constructed. The voltage for regulating the port impedance is derived from the harmonic information of the system, which contains the motor torque and the dc-link voltage. An analysis is conducted on the effect of the angle of impedance regulation voltage on the impedance optimization index. The ideal angle can be determined using entropy-weighted technique for order of preference by similarity to ideal solution (TOPSIS). This enables vector synthesis of the port impedance regulation voltage under the co-optimization of port impedance, which improves the coordination between the quality of the grid current and the harmonics of the motor torque.

Compared with the single working fluid, the binary mixture working fluid can further extend the operating temperature range and enhance the heat transfer performance of a thermosyphon. In this paper, an experimental test system was designed and implemented to study the heat transfer characteristics of the thermosyphon. Methanol employed as the base fluid, 10 kinds of binary mixtures were prepared by adding different volume fractions of deionized water and ethanol separately. The effects of filling ratio, heat flux, and working fluid type on the heat transfer characteristics of the thermosyphon were analyzed and discussed. Moreover, the start-up characteristics were also explored. The experimental result shows that the filling ratio has a significant impact on the performance of the thermosyphon, and the optimal filling ratio is about 30% in this study. The start-up times of the thermosyphon with different binary mixture working fluids remain consistently, which are in the range of 200–300 s. It is worth mentioning that the start-up time of methanol-based binary mixture working fluid with 5% DW is 200 s, which is nearly 33% earlier than that with 50% ethanol. The thermosyphon with methanol-based binary mixture working fluid containing 5% DW presents a reduction of 7.3 °C in the maximum temperature difference and a remarkable 57.0% decrease in thermal resistance when contrasted with the thermosyphon using methanol working fluid. The results of this paper have important significance for the practical application of methanol-based binary mixture working fluid.

Backscatter is an emerging ultra-low-power wireless communication technology for Internet-of-Things. However, as the widely used modulation scheme in OFDM systems, the combination of QAM and WiFi backscatter is not very satisfactory. To deploy QAM in the WiFi backscatter system, we propose PilotScatter, the first OFDM backscatter system supporting both 16-QAM modulation and non-redundant coding. These changes significantly improve the throughput of PilotScatter over previous backscatter systems. The key insight of PilotScatter is the use of pilot tones and differential demodulation. By modifying the phase and amplitude of pilot tones of the carrier signal, PilotScatter can modulate tag data on ambient WiFi with a 16-QAM scheme. At the receiver, PilotScatter uses a differential algorithm to demodulate tag data. It makes PilotScatter achieve 16-QAM demodulation without relying on ambient WiFi data and past symbols. We prototype PilotScatter using FPGAs, commodity radios, and USRPs. Comprehensive evaluations demonstrate that PilotScatter achieves up to 932.22 kbps throughput for WiFi 802.11g, and the backscatter communication range (Tag-to-Rx) is up to 19 m in Line-of-Sight (LoS) and 16 m in Non-Line-of-Sight (NLoS). Compared with the symbol-level backscatter research, PilotScatter has 7.49x and 3.78x goodput gains over MOXcatter and RapidRider, respectively.

To treat critical-sized defects in long bones, a novel structure was proposed by introducing a Haversian biomimetic structure and trabecular-like irregular pore morphology (IPM) structure into functional gradient porous scaffolds (FGPS). The outer shell structure is a "hard" structure providing mechanical support, and the inner core is a "soft" structure with radial gradient distribution IPM structure to promote the ingrowth of bone tissue. In this study, different inner core continuous gradient FGPS (GIPM) and layered FGPS (IPM, and BCC structure), with different outer shell pore sizes (300, 500, and 700 μm) were designed and fabricated by selective laser melting. The results show the stiffness of those FGPS was between 20.0 and 28.7 kN/mm, which is similar to the native femur (with a stiffness ranging from 7.2 to 11.7 kN/mm) of similar size. The GIPM-500 has more uniform stress distribution and stress transfer, resulting in superior load-bearing efficiency. Moreover, GIPM-500 exhibited excellent fatigue durability, achieving excellent fatigue cycles of more than 1 × 106cycles. Cell immunofluorescence shows that the GIPM-500 and IPM-500 are more suitable for cell attachment and growth due to the flexibility of the local porosity and curvature. Bone defect repair simulations showed that GIPM-500 can meet normal load-bearing requirements while having little impact on the normal stress-strain trajectory. This work provides a novel biomimetic scaffold design containing both cortical and trabecular bone components for repairing critical-size defects in long bones.

Hydrogen energy has an important role in superconducting energy storage cooling and materials synthesis. As the power-to-hydrogen (P2H) loads, alkaline electrolytic cells (AEC) and proton exchange membrane electrolytic cells (PEMEC) have different technical characteristics (TCs). This paper proposes an optimal capacity configuration model for the hybrid electrolytic cells P2H system in distribution system (DS). Firstly, a unified operating model for the electrolytic cell is established. Secondly, the optimal capacity configuration model is proposed with the objective function to minimize the total cost of the DS, including the numbers and capacity configuration of the hybrid electrolytic cells. Finally, the proposed model is verified by using the modified IEEE 33-bus system. The results show the total cost of the proposed model reduced by 4% and 11%, the hydrogen production power increase of 0.26% and 0.52% compared to the AEC and PEMEC configurations only. The study provides a reference for the configuration of large-scale hybrid electrolytic cells in power system.

In the flux model–based position sensorless permanent magnet synchronous motor (PMSM) drive system, cross-saturation effect, parameter mismatch, and other factors cause errors in the flux and position estimation. In this article, a novel adaptive position estimation error suppression method based on a limit cycle oscillator (LCO) is proposed for PMSM drives. Based on the estimation error analysis of the hybrid flux model–based sensorless control strategy, by tracking and minimizing the back electromotive force error in the estimated frame, the stator flux rotation trajectory can be corrected adaptively. The LCO-based adaptive algorithm offers a novel approach for the suppression of position estimation offset error and can further suppress the harmonic error by correcting the vector angle of active flux due to its self-excited oscillation function. Furthermore, the stability, the parameter sensitivity, and the parameter tuning are investigated theoretically in detail. The effectiveness of the proposed method is verified by experiments on a 2.2-kW PMSM drive platform.

The overmodulation (OVM) strategy can improve the modulation index (MI) of the output voltage and expand the speed and torque range in the field weakening (FW) region. However, the motor current harmonics would be increased. To solve this issue, this article proposes an OVM voltage boundary adaptation-based FW strategy for high-speed permanent magnet synchronous motor (PMSM) drives. By analyzing the frequency spectrum of the OVM output voltage, an FW current model containing the harmonics is established. The adaptation strategy between different voltage boundaries is adopted in the dynamic state by inserting more continuous voltage vectors. The adaptive regulation of the optimized voltage boundary in the steady state is proposed by increasing the utilization of the dc-bus voltage considering the THD limitation of the phase current. The motor operating state is judged by the speed and current information, and the smooth switching between dynamic and steady states is realized. A contour plot of MIs is constructed to classify the OVM levels, and the boundary initial value curve is fitted to reduce the adaptive time. The proposed strategy can maximize the motor torque and speed satisfying the THD limitation, which is experimentally verified on a 6-kW high-speed PMSM platform.

To enhance the lifespan of Vienna rectifiers, the electrolytic capacitors in the dc link can be substituted with slim-film capacitors. However, the decrease in capacitance leads to an increase in neutral point (NP) voltage fluctuation and input current harmonics. To solve this issue, a model predictive control strategy based on three-vector duty cycle optimization is proposed. The negative influence of reduced capacitance and high modulation index on the NP fluctuation and the input current harmonics is analyzed. In order to suppress the NP fluctuation and eliminate weighting factors, the subsectors division and the NP voltage hysteresis are introduced to select effective voltage vectors, reducing 27 candidate voltage vectors to three sets of switch sequences. Then the Karush–Kuhn–Tucker condition is used to derive the duty cycle of the convex quadratic optimization issue within the boundary and constraint interval. With the proposed strategy, both the NP voltage fluctuation and the input current harmonics can be reduced simultaneously. The effectiveness is verified on an electrolytic capacitorless Vienna rectifier platform.

Due to the easy oxidation of Sn2+, which leads to form tin vacancy defects and poor perovskite film quality, caused by the rapid crystallization rate in tin-based perovskite solar cells (PSCs), their efficiency lags far behind that of lead-based PSCs. To improve the photovoltaic (PV) performance and stability of FA0.9PEA0.1SnI3-based PSCs (T-PSCs), a small amount of Pb(SCN)2is introduced into a perovskite precursor as an antioxidant, and acetaminophen (ACE) with various functional groups is used to modify a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/perovskite interface. The results show that the Pb(SCN)2additive and ACE interfacial modification can not only optimize energy level alignment in T-PSCs but also inhibit Sn2+oxidation to reduce the trap-state density, resulting in promoted carrier transport. The synergetic effect of the Pb(SCN)2antioxidant and ACE interfacial modification significantly reduces nonradiative recombination and improves the PV performance and stability of T-PSCs. Consequently, the unsealed T-PSCs with the Pb(SCN)2additive and ACE modification achieve a champion efficiency of 12.04% and maintain 99% of their initial PCE after being stored in N2for more than 2100 h, while reference T-PSCs demonstrate a champion PCE of 6.20% and retain only 72% of its initial PCE. Moreover, the modified T-PSCs without encapsulation demonstrate much better stability in humid air.

When grid voltage is unbalanced and distorted, the input current harmonics in Vienna rectifier will increase. To solve the issue, a grid voltage sensorless control strategy based on direct-axis current orientation is proposed for Vienna rectifier. In the reference frame, by ensuring that the reference voltage and the input current are in phase, the proposed strategy can avoid the separate operation of positive and negative sequence while reducing the zero-crossing distortion of the input current. The virtual reference voltage is constructed according to the current path and conducting state in the diode rectifier mode, which can reduce the overcurrent during the start-up process. To reduce the harmonics of input current caused by unbalanced grid voltage, the direct axis current control strategy with low-frequency fluctuation is developed in the fundamental plane. In the harmonic plane, the harmonics of the grid voltage are estimated in real time by combining single phase second-order generalized integral, which can suppress the harmonics of the input current under distorted grid voltage. The effectiveness of the proposed strategy is verified on a Vienna rectifier platform.

The treatment of bone defects has always been a difficult problem in orthopedic clinical practice, and research on new materials is currently a hot topic. In this study, the biological safety and bone induction ability of a new magnesium-based amorphous alloy (Mg66Zn30Ca3Sr1) and zinc–magnesium powder were verified and compared in animal experiments. Thirty Sprague–Dawley rats were randomly divided into three groups, and a bone defect was made in the lateral condyle of the femur of the left hind limb. The blank group closed the wound after establishing the bone defect model, the control group added zinc–magnesium powder and chondroitin sulfate gel, and the experimental group added magnesium–zinc–calcium–strontium alloy and chondroitin sulfate gel with the same volume. Peripheral venous blood of rats was collected at 4, 8, and 12 weeks postoperatively, and alanine aminotransferase (ALT), aspartate transferase, creatinine, blood urea nitrogen, magnesium ion, and zinc ion levels were evaluated. The expression levels of bone morphogenetic protein 2 (BMP-2), osteoprotegerin (OPG), osteopontin (OPN), core binding factor α1 (RUNX2), and alkaline phosphatase (ALP) were detected using enzyme-linked immunosorbent assay (ELISA). After the rats were euthanized, samples were taken. X-rays and micro-computed tomography (CT) images of the bone defect were obtained, and hematoxylin and eosin and Masson staining were performed. This study shows that amorphous magnesium–zinc–calcium–strontium alloy is a biodegradable metal with good biocompatibility and bone induction and has good application prospects in treating bone defects.

When Vienna rectifier operates at light load conditions, small load power difference of bipolar dc bus leads to dc offset of neutral point (NP) voltage due to the limitation of dc-link power, increasing the voltage stress on switching devices. To solve this problem, a dc offset reduction of NP voltage strategy based on the vector phase angle difference (VPAD) optimization is proposed. By analyzing the relationship between the magnitude of zero-sequence component and the duty cycles of voltage vectors, the maximum power difference of the conventional strategy is obtained. The proposed strategy illustrates that VPAD can adjust the NP current based on the contour of the NP current, and the maximum VPAD is limited to satisfy the reference voltage and input current have the same sign. To increase the NP current, the VPAD is optimized by introducing the fluctuating reactive current, and the active current disturbance is injected to regulate the change rate of NP current. Therefore, the proposed strategy can significantly reduce the dc offset of NP voltage under light load conditions at the cost of the input current harmonics and the dc-link voltage fluctuation. Finally, the effectiveness of the proposed strategy is verified on a Vienna rectifier platform.

Permanent magnet linear synchronous motor (PMLSM) suffers from inherent thrust ripples, which cause vibration and noise and worsen the control performance. In this article, an iterative learning thrust ripple suppression method based on a proportional resonant internal model extended state observer (PR-IMESO) is proposed for PMLSM drives. A P-type iterative learning controller (PILC) with the forgetting factor is constructed to suppress the detent force which is the main component of thrust ripples and periodic force ripples. On this basis, PR-IMESO is constructed to further suppress the detent force and the residual disturbance in thrust ripples. In addition, the convergence, stability, and parameter sensitivity of the suppression method are analyzed. The proposed PR-IMESO-based PILC suppression method can suppress thrust ripples of PMLSM pertinently according to their characteristics to achieve overall control performance improvement. Finally, the effectiveness of the proposed method is verified on a 750-W PMLSM experimental platform.

Phosphorus is a promising candidate for high energy density lithium/sodium-ion batteries due to its high capacity. However, the dynamics of carrier shuttling in the alloyed phosphorus anode are quite complex due to the multiple phase transitions during the lithiation/sodiation process. Here, we identify Li(Na)P and Li(Na)3P as stable phases from both ex situ and in situ X-ray diffraction measurements of black phosphorus (BP). Our results regarding the dynamics of lithiation/sodiation indicate that the entire reaction could be limited by sluggish lithium/sodium ion migration in the stable phases, Li(Na)P and Li(Na)3P, supported by ab initiomolecular dynamics (AIMD) simulations. Additionally, Li3P has higher activation energies and correspondingly lower ion conductivity than LiP, making it the key role in the whole dynamics of lithium-ion transport during the lithiation process. In comparison, the dynamics of sodiation exhibit quite active behavior due to lower energy barriers for sodium-ion transport. However, the electrochemical performance of sodium-ion batteries suffers from a large charge transfer resistance at the electrode/electrolyte interface due to the generation of corrosive Na3P. Therefore, the construction of a stable solid electrolyte interphase (SEI) is crucial to improving the electrochemical performance of phosphorus anodes.

Serious open-circuit voltage (Voc) loss originating from nonradiative recombination and mismatch energy level at TiO2/perovskite buried interface dramatically limits the photovoltaic performance of all-inorganic CsPbIxBr3–x(x= 1, 2) perovskite solar cells (PSCs) fabricated through low-temperature methods. Here, an ionic liquid (IL) bridge is constructed by introducing 1-butyl-3-methylimidazolium acetate (BMIMAc) IL to treat the TiO2/perovskite buried interface, bilaterally passivate defects and modulate energy alignment. Therefore, the Vocof all-inorganic CsPbIBr2PSCs modified by BMIMAc (Target-1) significantly increases by 148 mV (from 1.213 to 1.361 V), resulting in the efficiency increasing to 10.30% from 7.87%. Unsealed Target-1 PSCs show outstanding long-term and thermal stability. During the accelerated degradation process (85 °C, RH: 50∼60%), the Target-1 PSCs achieve a champion PCE of 11.94% with a remarkable Vocof 1.403 V, while the control PSC yields a promising PCE of 10.18% with a Vocof 1.319 V. In particular, the Vocof 1.403 V is the highest Vocreported so far in carbon-electrode-based CsPbIBr2PSCs. Moreover, this strategy enables the modified all-inorganic CsPbI2Br PSCs to achieve a Vocof 1.295 V and a champion efficiency of 15.20%, which is close to the reported highest PCE of 15.48% for all-inorganic CsPbI2Br PSCs prepared by a low-temperature process. This study provides a simple BMIMAc IL bridge to assist bifacial defect passivation and elevate the photovoltaic performance of all-inorganic CsPbIxBr3–x(x= 1, 2) PSCs.

The field-weakening (FW) control strategy with voltage angle regulation has the advantages of fast speed and current response by directly decoupling the voltages. For suppressing the current harmonics, this article proposes a novel active-damping-based FW control strategy for high-speed surface-mounted permanent magnet synchronous motor (SPMSM) drives. The resonant issue in the voltage-angle regulated system is analyzed, and the d-axis current is adopted to compensate the voltage angle, which introduces the additional impendence at the resonant frequency to reduce the d-q axis current harmonics. An offline coefficient design method based on the frequency characteristic and step response is proposed to construct the contour map seeking for optimal coefficients, which achieves significant reductions on current harmonics and improves the robustness of the proposed method on mismatches of motor parameters. The damping ratio of the current loop is determined by the integral coefficient with a wider range. Hence, the adaptability of the FW voltage angle regulation can be guaranteed under different speed and load conditions. The effectiveness of the proposed strategy is verified on the 6-kW high-speed SPMSM platform.

The use of controlled excitation makes pervasive backscatter communication difficult to achieve and the redundant modulation severely limits the performance of the system. We present a novel WiFi backscatter system that can take uncontrolled OFDM WiFi signals as excitations and efficiently embed tag data at the single-symbol rate. Specifically, we are the first to discover the fundamental reason why the previous systems have to rely on multi-symbol modulation, which makes it possible to demodulate tag data on the single-symbol level. Further, we design deinterleaving-twins decoding that can reuse any uncontrolled WiFi signals as carriers to backscatter tag data. Moreover, we present how to robustly handle high-order excitations, including different demapping rules for diverse excitations and three different bit-translation methods for decoding. To verify the effectiveness of our proposal, we prototype our solution using various FPGAs and SDRs. Comprehensive evaluations show that our solution’s maximum throughput is 3.92x and 1.97x better than FreeRider and MOXcatter. In addition, with 16QAM excitations, the decoding BERs of majority voting are around 5%, which is 10x better than subsequence matching and jaccard similarity methods. Meanwhile, the throughput of deinterleaving-level demodulation is 2x better than payload-level demodulation with 16QAM ambient traffic.

Rockburst is a highly destructive geological hazard that can cause casualties and equipment damage. To achieve high-accuracy discrimination of rockburst intensity, this article proposes an improved model that addresses the inefficient maximum membership principle used in traditional rockburst fuzzy evaluation models. The stress coefficient σθ/σc, brittleness coefficient σc/σt, and elastic deformation energy index Wetare selected as evaluation indicators for rockburst classification. Subjective and objective weights are obtained using the Delphi method and entropy weight method (EWM). Three types of membership function distribution forms are then used to obtain the membership degrees of each indicator to rockburst grades: trapezoidal membership function (TMF), normal membership function (NMF), and quadratic parabolic membership function (QPMF). Finally, six traditional models and six improved models are established using the maximum membership principle (MMP) and weighted average-maximum membership principle combination evaluation principle (WMP), respectively. Based on the analysis of 100 sets of rockburst field data, the accuracy, precision, recall, and F1-score of the improved evaluation model are increased by 11.3%, 0.097, 0.068, and 0.089, respectively, compared to the traditional model. The Delphi-NMF-WMP model is selected as the best model, with four performance indices reaching 97.0%, 0.979, 0.979, and 0.978. The best model is applied to evaluate the rockburst intensity of the Cangling Tunnel, Dongguashan Copper Mine, and Jiangbian Hydropower Station Diversion Tunnel, with evaluation results consistent with the actual situation, demonstrating the reliability and scientificity of the model.

AimsTo report the incidence and associated risk factors for developing suspected and definitive glaucoma after bilateral congenital cataract (CC) removal with a 5-year follow-up.MethodsSecondary analysis of a prospective longitudinal cohort study. Bilateral CC patients who had undergone cataract surgery between January 2011 and December 2014 at Zhongshan Ophthalmic Centre were recruited. Suspected glaucoma was defined as persistent ocular hypertension requiring medical treatment. Definitive glaucoma was defined as accompanied by the progression of glaucomatous clinical features. According to postoperative lens status in 5 years follow-up: 130 eyes in the aphakia group; 219 in the primary intraocular lens (IOL) implantation group and 337 in the secondary IOL implantation group. The Kaplan-Meier survival and Cox regression analyses were used to explore the cumulative incidence and risk factors for suspected and definitive glaucoma.ResultsThree hundred fifty-one children (686 eyes) with bilateral CCs were enrolled in the study. The mean age at surgery was 1.82±2.08 years, and the mean follow-up duration was 6.26±0.97 years. Suspected and definitive glaucoma developed at a mean time of 2.84±1.75 years (range 0.02–7.33 years) postoperatively. The cumulative incidence of suspected and definitive glaucoma was 9.97% (35 of 351 patients), including 6.12% (42 eyes) for definitive glaucoma and 2.48% (17 eyes) for suspected glaucoma. Microcornea (HR 4.103, p<0.0001), CC family history (HR 3.285, p=0.001) and initial anterior vitrectomy (HR 2.365 p=0.036) were risk factors for suspected and definitive glaucoma. Gender, age at surgery, intraocular surgery frequency, length of follow-up and frequency of neodymium-doped yttrium aluminumaluminium garnet laser were non-statistically significant. Primary IOL implantation was a protective factor (HR 0.378, p=0.007).ConclusionsIdentifying suspected and definitive glaucoma after bilateral CC surgery can lower the risk of secondary blindness in children. Patients with related risk factors need to pay more attention and thus reach early intervention and treatment during clinical practice. Primary IOL implantation may be a potential protective factor, need more clinical trials to be verified.Trial registration numberNCT04342052.

This article investigates the beat phenomenon in permanent magnet synchronous motor (PMSM) drives with small direct current link (dc-link) capacitors caused by the interactions of the fundamental current and the dc-link inspired harmonics. The proposed impedance reshaping based beatless method not only reduces the low-frequency envelop in motor currents, but also improves the quality of grid currents. The harmonics in the beat current are analyzed in an impedance perspective, and a beatless control strategy is proposed by reshaping the impedance of the PMSM drive system at dominated harmonics. By generating the adjusting currents at the dominated harmonics on motor current vector, the small-signal model of the system is immune to the variation of the steady-state values, which ensures the validity of the beat suppression over a wider operating range. Experimental results show the effectiveness of the proposed method in a prototype of PMSM drive with small dc-link capacitors.

The fixed-gain position observer for sensorless interior permanent magnet synchronous motor (IPMSM) drives requires repeated trials for parameter tuning and has poor dynamic response capability. A novel adaptive step-size predictive phase-locked loop (ASS-PPLL) based rotor position estimation method is proposed to improve dynamic performance in this article. A cost function using position-tracking error decoupled from a high-frequency current response through a high-frequency square-wave injection is established. In addition, the step-size and direction are automatically adjusted by the predefined cost function to speed up the iterative search for an optimal rotor position estimate in a finite position set. Compared with the fixed-gain observers, the proposed ASS-PPLL effectively improves dynamic performance without a complex and time-consuming parameter tuning process. Compared with the conventional predictive PLL, the proposed method reduces the computational burden with fewer iterations, while ensuring the position estimation accuracy. Finally, the effectiveness of the proposed ASS-PPLL is comprehensively verified on a 2.2-kW IPMSM drive platform.

Active damping strategies can suppress the LC resonance for electrolytic capacitorless permanent magnet synchronous motor (PMSM) drives, yet it is difficult for the fixed damping coefficient to achieve optimal performance under different operating states. In this article, a novel adaptive virtual admittance reshaping-based resonance suppression strategy is proposed. The influence regularity of the virtual admittance amplitude and angle on the suppression capability of the LC resonance is analyzed. Furthermore, the relationship between the total harmonic distortion of the grid current and the harmonic factor of the dc-link current is established. According to the variation tendency of the harmonic factor, the optimal control of the grid current quality under different operating states can be realized by adaptively adjusting the virtual admittance amplitude. Aiming at the open-loop characteristics of the active damping strategy, an adaptive mechanism for the comprehensive adjustment of the time and admittance optimization steps is constructed. Experimental results validate the effectiveness of the proposed method in reduced dc-link capacitance PMSM drives.

Exosomal microRNAs (miRNAs) play critical regulatory roles in many cellular processes, and so how to probe them has attracted increasing interest. Here we propose an aptamer-functionalized dimeric framework nucleic acid (FNA) nanoplatform for effective capture of exosomes and directly probing internal miRNAs with electrochemiluminescence (ECL) detection, not requiring RNA extraction in conventional counterparts. A CD63 protein-binding aptamer is tethered to one of the FNA structures, allowing exosomes to be immobilized there and release internal miRNAs after lysis. The target miRNA induces the formation of a Y-shaped junction on another FNA structure in a close proximity state, which benefits the loading of covalently hemin-modified spherical nucleic acid enzymes for enhanced ECL readout in the luminol-H2O2system. In this facile way, the ultrasensitive detection of exosomal miR-21 from cancer cells is accomplished and then used for cell apoptosis analysis, indicating that the oncogene miR-21 negatively participates in the regulation of the apoptotic process; namely, downregulating the miR-21 level is unbeneficial for cancer cell growth.

In a position sensorless permanent magnet synchronous motor (PMSM) drive system, parameter mismatch will introduce estimation error in the stator flux and rotor position information. A novel flux observer based on an enhanced second-order generalized integrator (SOGI) with a limit cycle oscillator is proposed to improve the robustness of sensorless PMSM drives. Based on the SOGI structure, the proposed method constructs a nonlinear oscillator with a self-excited oscillation function that can maintain the flux trajectory oscillation even in the absence of the input stator electromotive force. The enhanced observer can converge the stator flux trajectory to its expected state under external disturbances and reduce position estimation error. Moreover, the proposed limit cycle oscillator can improve the harmonic suppression ability of the SOGI-based flux observer. The convergence and robustness of the enhanced observer are both investigated, demonstrating that the proposed method can improve the performance of the flux observer. The effectiveness of this method is verified by experiments on a 2.2-kW PMSM drive platform.

The green hydrogen–electric coupling system can consume locally generated renewable energy, thereby improving energy utilization and enabling zero-carbon power supply within a certain range. This study focuses on a green hydrogen–electric coupling system that integrates photovoltaic, energy storage, and proton exchange membrane electrolysis (PEME). Firstly, the impact of operating temperature, power quality, and grid auxiliary services on the characteristics of the electrolysis cell is analyzed, and a voltage model and energy model for the cell are established. Secondly, a multi-operating conditions adaptability experiment for PEME grid-connected operation is designed. A test platform consisting of a grid simulator, simulated photovoltaic power generation system, lithium battery energy storage system, PEME, and measurement and acquisition device is then built. Finally, experiments are conducted to simulate multi-operating conditions such as temperature changes, voltage fluctuations, frequency offsets, harmonic pollution, and current adjustment speed. The energy efficiency and consumption is calculated based on the recorded data, and the results are helpful to guide the operation of the system.

Loss of the PTEN tumour suppressor is one of the most common oncogenic drivers across all cancer types1. PTEN is the major negative regulator of PI3K signalling. The PI3Kβ isoform has been shown to play an important role in PTEN-deficient tumours, but the mechanisms underlying the importance of PI3Kβ activity remain elusive. Here, using a syngeneic genetically engineered mouse model of invasive breast cancer driven by ablation of both Ptenand Trp53(which encodes p53), we show that genetic inactivation of PI3Kβ led to a robust anti-tumour immune response that abrogated tumour growth in syngeneic immunocompetent mice, but not in immunodeficient mice. Mechanistically, PI3Kβ inactivation in the PTEN-null setting led to reduced STAT3 signalling and increased the expression of immune stimulatory molecules, thereby promoting anti-tumour immune responses. Pharmacological PI3Kβ inhibition also elicited anti-tumour immunity and synergized with immunotherapy to inhibit tumour growth. Mice with complete responses to the combined treatment displayed immune memory and rejected tumours upon re-challenge. Our findings demonstrate a molecular mechanism linking PTEN loss and STAT3 activation in cancer and suggest that PI3Kβ controls immune escape in PTEN-null tumours, providing a rationale for combining PI3Kβ inhibitors with immunotherapy for the treatment of PTEN-deficient breast cancer.

Metaverse has been going viral across the globe, and virtual reality head‐mounted displays (VR‐HMDs) as the basic infrastructure and entrance to cater to this evolution of social interaction are showing rapid development recently. Pancake optics based on optical path folding provides the feasibility of VR‐HMDs in the form of glasses and is wide recognition. The pancake system has become the current mainstream owing to its large exit pupil diameter (EPD), high resolution, novel compact, and lightweight. Owing to the use of polarization elements, the birefringence in the lens will change the polarization state of the light, resulting in uneven brightness and stray light, seriously reducing the optical performance of the system, so it is necessary to control the birefringence of the lens. In this study, we proposed a pancake system based on a 2.1‐inch LCD display which achieves 10 mm EPD at 11 mm, diagonal field of view (FOV) of 96°, overall length (OAL) of the system less than 20 mm, and support diopter adjustment from ‐7D to ‐1D. The residual birefringence of the lens can be effectively suppressed in four stages: 1) controlling the thickness ratio between the center and the edge of the lens during the optical design, 2) setting a reasonable position and size of the injection gate and cooling system during the mold design process, 3) adopting reasonable injection parameters during the precision injection molding process and 4) eliminating the birefringence of the lens with the lens annealing process. Ultra‐precision machining and correction of the mold cores have been employed to achieve high surface accuracy and low birefringence of the lens. The optomechanical design, assembly, and adjustment process are discussed. Finally, the prototype of the pancake system is experimentally tested, and the results demonstrate pretty well.

Grid-side current harmonic (GCH) is an important issue in totem-pole bridgeless power factor correction (TBPFC) converters. In this article, a GCH suppression (GCHS) method based on input voltage feedforward active damping is proposed. First, an admittance model of the TBPFC converter considering the electromagnetic interference (EMI) filter and the time delay of the digital control system is established. The damping characteristics of the system are improved by constructing a virtual admittance, which does not require additional current and voltage sensors. Based on the admittance model analysis, the active damping can be matched and adapted to a wide power range. Through the extraction of harmonic information and the combination with current setting and modulation voltage information, the suppression of current harmonic under different loads can be realized. Besides, the sensitivity of the system parameters is analyzed. The system delay, load change, and system parameter change are considered in the design of active damping, so the current harmonics can be effectively suppressed in a wide power range. Finally, the effectiveness and feasibility of the proposed method are verified by experiments on a TBPFC converter platform.

In the high-frequency (HF) signal injection based position sensorless permanent magnet synchronous motor (PMSM) drives, there is an estimated position error caused by the cross-saturation effect and other factors. In order to suppress the position error, an HF injection angle self-adjustment based online suppression method is proposed in this letter. By tracking the sign of the increment of the absolute back electromotive force in the estimated frame, the criterion of the HF injection angle self-adjustment can be determined online and the position error can be mitigated effectively. This method can avoid the offline measurement or the variation of the operating state, which has a satisfactory suppression effect for the position error under different operating conditions. The effectiveness is verified by experiments on a 2.2-kW PMSM drive platform.

We present multiscatter, a novel battery-free backscatter design that can simultaneously work with multiple excitation signals for personal IoT sensors. Specifically, we show for the first time that the backscatter tag can identify various excitation signals in an ultra-low-power way, including WiFi, Bluetooth, and ZigBee. Further, we employ a new modulation approach, overlay modulation, that can leverage those excitation signals to convey tag data on top of productive data, which makes decoding both data possible with only a single personal radio. Moreover, we introduce a low-power listening scheme to improve energy efficiency. Since 2.4 GHz signals and personal radios are everywhere, multiscatter is readily deployable in our everyday IoT applications. We prototype multiscatter using an FPGA and various commodity radios. Extensive experiments show that for mixed 802.11b&n, Bluetooth and ZigBee signals, the average identification accuracy of four protocols is more than 93%. The maximal aggregate throughput of both productive and tag data is 278.4 kbps with a single Bluetooth radio. When the transmitter-to-tag distance is increased from 0.2 to 1.8 m, the maximal communication for BLE drops from 71 m to 29 m. And it can leverage excitation diversity to provide uninterrupted communication and greater throughput gains, whereas the single-protocol tag being idle when carrier signals are unavailable. With indoor office light as harvesting sources, the low-power listening scheme can support backscatter rate at 12 pkts/s.

The errors of gain and offset caused by the current sensor measurement can lead to the first and second harmonics in dq-axis currents of the permanent magnet synchronous motor (PMSM) drives. An adaptive-frequency harmonic suppression strategy based on the vector reconstruction for current measurement error is proposed. The dq-axis current vector is recoordinate transformed using the division-frequency position as the transformation matrix angle. Thus, the frequency of the fundamental component can be decoupled from that of the harmonics in the current vector. In this way, the single-frequency harmonic suppressor can be established in the reconstructed coordinate frame. The current vector error is converged by adaptively adjusting the filtering weight and frequency so as to eliminate the harmonics. In view of the change of fundamental frequency, the variable step of the convergence is used to obtain the ideal filtering effect at different speeds and reduce the negative impact of current sensor measurement errors. The effectiveness of the proposed method is verified on the 11.7-kW PMSM drive platform.

Good toilet hygiene can reduce the risk of pathogenic transmission. During flushing, pathogenic bacteria can be spread by the water droplets, especially in the toilet seat. Escherichia coli(E. coli) is one of the frequently occurring Gram-negative bacterial pathogens found in the toilet seats. In this study, we investigated the potential anti-E. coliactivity of some azobenzene compounds. Among them, compound 2, with the heterocyclic nitrogen in both phenyl rings, showed the strongest antibacterial effect on E. coli, with the minimum inhibitory concentration of 80 µg/mL and the minimum bactericidal concentration of 320 µg/mL Compound 2displayed a comparative zone of clearance [(14.50±2.29) mm] to that of ampicillin [(13.17±1.76) mm]. The reactive oxygen species (ROS) assay suggested that compound 2might induce the loss of bacteria viathe oxidative stress by eliciting the generation of intracellular ROS. We further examined the potential cytotoxicity of compound 2to the human skin HaCaT cells. Compound 2-treated skin cells showed a good maintenance of cellular morphology and a clear definition of cell nuclei, with a satisfactory cell viability (ca.90%) at 80 µg/mL Overall, compound 2would be a possible antibacterial coating agent for the surface sanitizer of the toilet seats to inhibit the growth of E. coli.

Existing online parameter identification methods of permanent magnet synchronous motors (PMSMs) are generally based on the voltage equations, the precision of which is affected by the cross coupling and magnetic saturation effects. In order to deal with this issue, a virtual-rotary-axis high-frequency signal injection based online parameter identification method is proposed in this article, where the cross coupling and magnetic saturation effects on the traditional dq-axis model are analyzed. On this basis, an optimized voltage model under the composite magnetic field rotary axis is introduced. In the proposed method, the cross-coupling angle and the dq-axis inductances can be identified by injecting the high-frequency signal into the constructed virtual rotary axis. In addition, the complex Simpson integral algorithm is adopted to obtain the information of the incremental and apparent inductances. Finally, the permanent magnet flux linkage can be estimated based on the composite magnetic field rotary axis voltage equations. The effectiveness and feasibility of the proposed method are verified by the experiments on a 2.2-kW PMSM drive.

Grid-side current phase shift (GCPS) is an important issue in totem-pole bridgeless power factor correction (TBPFC) converters. In this article, a virtual admittance reshaping based GCPS suppression method is proposed based on the establishment of the admittance model of the TBPFC converter including the EMI filter. The virtual admittance reshaping does not need additional current and voltage sensors and can realize complex admittance through a control algorithm. Thus, the current phase error can be adjusted to zero with the optimal design. The inherent admittance of the system is analyzed from the perspective of system frequency characteristics to extract leading-phase admittance. Then, the parallel admittance is produced through the inductance current for canceling it. The current reference and the modulation voltage are combined to realize obtaining the equivalent virtual admittance and meanwhile reduce the burden of the current regulator. The sensitivity of the system parameters is analyzed, and the saturation effect of the inductor and the error of the EMI filter parameters have little effect on admittance reshaping. Besides, the research method does not need to adjust parameters according to the load. The effectiveness of the proposed method is verified by experiments on a TBPFC converter platform.

The large fluctuating torque disturbance of the single-rotor permanent magnet compressor has a significant impact on the drive system. An adaptive Fourier-transform-based torque disturbance compensation method is proposed to improve the control performance in this article. Based on the analysis of compressor load torque characteristics, a self-adjusting strategy is proposed to reduce the compensation error of the traditional open-loop Fourier-transform scheme. The compensation current is adaptively generated by adopting an indirect iterative learning mechanism that can obtain the multifrequency torque disturbances information in real-time. The proposed method does not require the accurate compressor parameters and the discrimination of harmonic disturbances, which has satisfactory suppression ability for the multifrequency torque disturbance. The convergence and parameter sensitivity of the proposed method are analyzed theoretically. The effectiveness of this method is verified by experiments on a 1.5-kW permanent magnet compressor drive platform.

Modulation fluctuations will decrease the linear operation range and cause the reduction of dc-link utilization for reduced dc-link capacitance motor drives. In this article, a novel strategy for expanding the linear modulation region based on voltage vector angle regulation is proposed. The phase relationship between the voltage reference and the dc-link voltage fluctuation is carried out creatively to clarify the reduction of linear modulation margin. Based on the impedance matching method, the linear modulation region can be expanded by reducing the phase differences with the regulation of voltage vector angle. According to parameter and performance analysis of the proposed method, the dc-link utilization can be improved by 13.2%. Experimental results validate that the effectiveness of the proposed method.

Environmental and human health are adversely affected by oil and organic wastewater pollution of water resources. However, it has always been difficult to develop an adsorption material that is multifunctional and able to remove multiple pollutants. A new hierarchically porous polymers have been synthesized using high internal phase emulsions (HIPE) template, and further modification by a physico-chemical synergy method of epoxidized soybean oil (ESO) coupled with stearic acid (STA). The modified polyHIPE (E/S-polyHIPE) exhibit superhydrophobic properties with water contact angle as high as 161.12°, and exhibit excellent robustness and chemical resistance. Oil/water mixtures can be separated using E/S-polyHIPE with a high separation efficiency (99.00–99.42 %), and it has a high oil absorption capacity (16–28 g/g) for a wide range of oil types. After 15 separation cycles, the E/S-polyHIPE exhibits excellent separation efficiency (＞ 97 %) because of its promising mechanical durability. E/S-polyHIPE still performed outstanding oil absorption capacity for floating oil, underwater oil, and emulsified oil, also it can be used as a continuous in-situoil-water separator. An innovative approach to the fabrication of a sustainable multifunctional absorbent for oily wastewater is presented in this work, which illustrates the great potential for large-scale practical application.