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The frequency-domain measurement method of time delay based on laser intensity or phase noise as multifrequency signal source is proposed. The frequency-spectrum distribution of noise signal caused by the time delay is analyzed to extract the characteristic frequencies to derive the time delay. The experimental results with intensity noise source show that for the time-delay fiber ranging from 0.5 to 15 km in length, the measurement deviation compared to optical time-domain reflectometer (OTDR) results ranges from −0.0514% to 0.0949%, demonstrating good measurement accuracy. For multiple measurements of 5-km-long time-delay fiber, the measurement deviation range with intensity noise source is from 0.0417% to 0.0689%, with a characteristic frequency fluctuation of 11 Hz, corresponding to time-delay measurement resolution of $6.69\times 10^{-{9}}$ s. The deviation range of the measurement with phase noise source is from −0.2437% to 0.1257%, with a characteristic frequency fluctuation of 150 Hz, corresponding to time-delay measurement resolution of $9.11\times 10^{-{8}}$ s. Therefore, the time-delay measurement resolution for the two noise sources is lower than the minimum interval of $2\times 10^{-{6}}$ s, corresponding to a sample rate of 500 kHz. It also meets the precision requirements of shifting discrete-signal timing needed for common-mode suppression on phase or intensity noise in optical fiber sensor arrays.

A Pd-catalyzed asymmetric higher-order dipolar cycloaddition between allenyl carbonates and azadienes is achieved by exploiting novel alkylidene-π-allyl-Pd dipoles. This research provides a modular platform for the synthesis of challenging chiral endocyclic allenes bearing a medium-sized heterocyclic motif and a centrally chiral stereocenter in good yields with high enantio- and diastereoselectivities (29 examples, up to 97% yield, 97:3 er and >19:1 dr). Experimental and computational studies elucidate the possible reaction mechanism and the observed stereochemical results. Based on the mechanistic understanding, a new π-propargyl-Pd dipole was designed to further extend the success of the higher order dipolar cycloaddition strategy to the synthesis of 10-membered endocyclic alkynes from propargyl carbonates and azadienes (13 examples, up to 98% yield and 94.5:5.5 er).

For hydrophones with very-low frequency (VLF) and high detection resolution, elliptic-fitting phase-difference demodulation technology (EF-PDDT) will be investigated for suppressive effect on laser phase noise (LPN) and advantage of measuring VLF signal. The suppressive effect was analyzed by examining two types of phase noise resulting from center-frequency drift and linewidth of laser. The experimental results demonstrate that EF-PDDT achieves a suppressive effect of 44 dB on the phase signal, and the effect of 48 dB can be achieved on a wider linewidth laser. In the detection of VLF signals, EF-PDDT has higher information-utilization efficiency compared to quadrature phase demodulation technology, resulting in a reduction of data volume by 66 dB and circumventing the limitations imposed by long-term sampling due to equipment performance, thereby enhancing spectral resolution. Hence, EF-PDDT is an effective solution for improving the detection resolution of VLF signals and finding applications in fields, such as underwater communication and seismic-wave monitoring.

Deep reinforcement learning (DRL) provides a promising approach for the implementation of autonomous driving. By utilizing a trained DRL model as the longitudinal controller, the automated vehicle (AV) can generate optimal action outputs based on the state within a shorter time compared to traditional model predictive control (MPC) methods. However, the non-interpretability of neural networks poses a potential risk for real-world vehicle operation. This paper focuses on applying the Twin Delayed Deep Deterministic Policy Gradient (TD3), a state-of-the-art (SOTA) DRL algorithm, to train the longitudinal control model for AVs. We confirm the risks associated with the TD3-based longitudinal control model by assessing its violation of the rational driving constraint (RDC), which represents the basic conditions for normal driving behaviors. To mitigate these risks, we propose a novel model that integrates the TD3-based model with the intelligent driver model (IDM) using a new indicator called velocity response time (VRT). This indicator identifies risky outputs of the TD3-based model and calculates the combined weights of both the IDM and TD3-based models. This combination allows us to reduce risks associated with the non-interpretability of the neural network while also capturing the effect of engine time lag. Numerical simulations are conducted to evaluate the performance of the proposed combined model. The results demonstrate that the proposed combined model outperforms the TD3-based model, IDM, and another SOTA approach in terms of disturbance mitigation, safety improvement, and suppression of traffic oscillation. Additionally, the combined model exhibits greater computational efficiency than MPC, making it well-suited for real-time control of AVs.

Poppet valves have become increasingly significant in ensuring precise digital flow rate and pressure control in hydraulic systems, necessitating a more profound understanding of the geometrical properties of cavitation in them, as well as associated flow-choking conditions. Through a comparative analysis with experimentally observed cavity images, we found that large eddy simulation (LES) turbulence modeling effectively replicates the geometrical properties of cavitation in these valves. The analysis demonstrated that cavitation is generated from vortices that result from the interaction between the notch contracta flow and the surrounding fluid structure. Variations in the internal or external vena contracta conditions result in fixed or discrete cavities, and the length-to-diameter ratio serves as a measure of the transition between internal and external vena contracta flow properties. This study establishes a threshold length-to-diameter ratio of approximately 2 for the tested poppet valves. More specifically, in notch structures with a smaller valve opening, longer sealing length, and smaller throttling angle (corresponding to a larger length-to-diameter ratio), the liquid-to-vapor transfer process is more evident than that in the reverse direction. A long-standing vapor cavity becomes fixed inside the notch, leading to a more pronounced flow-choking phenomenon. In contrast, for structures with a smaller length-to-diameter ratio, the cavitation process for discrete vapor cavities is more complete, ensuring fluid flow continuity and significantly reducing the occurrence of the flow-choking phenomenon.

Inspired by nature, materials scientists are highly motivated to achieve efficient control over building blocks at the molecular level for the fabrication of robust materials. Highly specific supramolecular hydrogen bonding between complementary nucleobases provides us with a straightforward and feasible route to precisely placing molecular motifs in polymer materials. In this work, we have demonstrated that precise supramolecular hydrogen-bonding pairing of nucleobase-containing monomers endows the attained polymer network with prominent mechanical properties, including high toughness, outstanding energy dissipation, excellent damping capacity, and good crack resistance. Complementary nucleobases adenine- and thymine-containing monomers with long alkyl chains were prepared, and the influence of distinct solvents on their hydrogen bond (H-bond)-forming capacity was explored. The H-bond-supporting solvent such as chloroform gives a high association constant of 36.0 M–1, while the H-bond-competitor solvent such as N,N-dimethylformamide generates a weak binding of only 2.8 M–1. The covalent “locking” of the precise supramolecular pairing of building blocks results in the formation of well-defined networks with a high supramolecular cross-linking density and activation energy, manifesting outstanding mechanical properties. This work reports an efficient route to constructing robust polymer materials by precisely controlling the hydrogen-bonding pairing of bioinspired nucleobase-containing building blocks.

With the increasing penetration of wind and solar energies, the accompanying uncertainty that propagates in the system places higher requirements on the expansion planning of power systems. A source-grid-load-storage coordinated expansion planning model based on stochastic programming was proposed to suppress the impact of wind and solar energy fluctuations. Multiple types of system components, including demand response service entities, converter stations, DC transmission systems, cascade hydropower stations, and other traditional components, have been extensively modeled. Moreover, energy storage systems are considered to improve the accommodation level of renewable energy and alleviate the influence of intermittence. Demand-response service entities from the load side are used to reduce and move the demand during peak load periods. The uncertainties in wind, solar energy, and loads were simulated using stochastic programming. Finally, the effectiveness of the proposed model is verified through numerical simulations.

The purpose of this paper is to study the practice of multimedia technology in the teaching of scientific and technical English. With the rapid development and popularisation of computer technology and the deepening of educational concepts, multimedia-assisted English teaching has become one of the most important foreign language teaching modes at present. This study firstly analyses the impact of multimedia technology on English teaching, secondly faces the advantages and challenges of multimedia technology in the teaching process, and finally explores the use and effect of multimedia technology in scientific and technological English teaching based on the data of the survey and research. The results of the study show that for college English teachers in colleges and universities, they should fully explore the advantages of multimedia technology in the process of using it and use it skillfully in teaching practice, which will have a positive effect on improving the quality of English teaching and deepening the reform of college English teaching.

Image acquired by camera sensors suffers from low contrast and poor visibility under low-light conditions. Given the importance of enhancing low-light images, this article presents an innovative method known as the self-calibrating neural network (SCNet). This approach involves the extraction of a lighting adjustment feature map (LafMap) from the input image. Matrix operations are then employed on the input image to derive an intermediate image, which is subsequently optimized through self-calibration (SC) to produce the final output image. The SCNet approach has proven effective in experimentation, as indicated by the peak signal-to-noise ratio (PSNR) values, demonstrating a 6.1% increase compared with the baseline on the low-light dataset (LOL dataset). The SCNet can be trained without the necessity for reference images, overcoming the challenge of insufficient enhancement often observed in very low-light images, which is a prominent problem in existing unsupervised low-light enhancement methods.

To investigate the impact of uncertain variability on multiterminal dc distribution systems and provide an efficient simulation tool, this article develops a stochastic transient simulation method based on dynamic phasor (DP). Starting from the lumped elements, the dynamic phasor models of the elements with parameter migration are established first, as well as the corresponding dynamic companion circuits used in digital simulation. By introducing the switching function and low-frequency approximation, the DP-based companion circuit of the voltage source converter is formulated, and the revised nodal voltage equations that can be solved in the framework of Electromagnetic Transients Program are also derived. Then, combined with the discussion on the ill condition of the nodal admittance matrix, the main process of DP-based stochastic transient simulation and the hybrid simulation scheme integrating electromagnetic transient (EMT) simulation are further proposed. Through the comparison with the full EMT simulation and physical experiments, the effectiveness of the DP-based dynamic companion circuits is validated, as well as the efficiency of the proposed simulation method.

During periods of extreme weather conditions, airport closures, or other unforeseen circumstances, air-lines frequently encounter disruptions in their flight schedules, posing flight recovery as a recurrent operational challenge. This paper aims to explore the impact of passenger transfer costs on flight recovery across various route types. Drawing on established methods used to calculate aircraft maintenance and crew assignment costs, this study utilizes an improved large-scale neighborhood search algorithm to perform a large number of calculations on a realistic dataset of airlines, meticulously analyzes the amalgamation of passenger transfer costs across different route types and proposes tailored strategies to mitigate disruptions. Through simulation experiments, the research evaluates the influence of various passenger transfer methods on flight recovery across diverse route types, with the goal of furnishing airlines with more adaptable and targeted decision support.

This paper investigates the mechanisms of spurious contents in a ring-VCO-based sub-sampling phase-locked-loop (SSPLL). An area-efficient solution to suppress reference spurs in a ring-VCO-based SSPLL is proposed using an auxiliary capacitor-multiplier-based delay-locked loop (DLL). Besides, the implementation of a finite state machine circuit with a narrow dead zone improves the relocking time and reduces the power consumption of the PLL. Implemented in a 0.18- $\mu \text{m}$ CMOS technology, the SSPLL has an active area of 0.051 mm2, while consuming a dc power of 4.89 mW at an output frequency of 2.4 GHz. Based on measurement results, the proposed circuit achieves an in-band phase noise of -107 dBc/Hz at 1-MHz offset and a reference spur of -70 dBc. The integrated RMS jitter from 1-kHz to 10-MHz interval is 877.5 fs.

AE-CuNCs with excellent fluorescence were prepared by a templated method.

Conjugate addition is among the most important synthetic protocols for constructing carbon skeletons and is widely used to synthesize natural products and drugs. However, asymmetric catalysis studies have mainly focused on constructing stereogenic centers arising from conjugate alkenes. Here, we report the first photoinduced cobalt-catalyzed dynamic kinetic reductive conjugate addition reaction that enables the formation of heterobiaryls with axial chirality (45 examples, up to 91% yield and 97% ee). This method features mild reaction conditions, good functional-group tolerance, and excellent enantiomeric control. Significantly, large amounts of metal waste and precious metal catalysts can be avoided under these conditions. Migration of the chiral arylcobalt species into the alkene might be the rate-determining step based on kinetic studies.

The ultrasensitive and quantitative detection of renal cancer protein biomarkers present at ultralow concentrations for early-stage cancer diagnosis requires a biosensing probe possessing ultrahigh detection sensitivity and remarkable biosensing selectivity. Here, we report an optical microfiber integrated with Ti3C2-supported gold nanorod hybrid nanointerfaces for implementation in ultrasensitive sensing of the carbonic anhydrase IX (CAIX) protein and renal cancer cells. Because the evanescent field of the fiber is strongly coupled with nanointerfaces in the near-infrared region, the proposed optical microfiber biosensor achieves ultrahigh-sensitivity detection of the CAIX protein biomarker with ultralow limits of detection (LODs) of 13.8 zM in pure buffer solution and 0.19 aM in 30% serum solution. In addition, the proposed sensor also successfully and specifically recognizes living renal cancer cells in cell culture media with a LOD of 180 cells/mL. This strategy may serves as a powerful biosensing platform that combines the quantification of protein biomarkers and cancer cells, resulting in a higher accuracy of early-stage renal cancer diagnosis and screenings.

Fusarium fujikuroiis one of the dominant phytopathogenic fungi causing rice bakanae disease worldwide. Cyclobutrifluram is a novel succinate dehydrogenase inhibitor (SDHI), which shows strong inhibitory activity against F. fujikuroi. The baseline sensitivity of 112 F. fujikuroito cyclobutrifluram was determinated with a mean EC50value of 0.025 μg/mL. A total of 17 resistant mutants were obtained by fungicide adaptation and displayed equal or slightly weaker fitness than parental isolates, which suggests that the resistance risk of F. fujikuroito cyclobutrifluram is medium. A positive cross-resistance was detected between cyclobutrifluram and fluopyram. The amino acid substitutions H248L/Y of FfSdhB and G80R or A83V of FfSdhC2conferred cyclobutrifluram resistance in F. fujikuroi, which was validated by molecular docking and protoplast transformation. The results indicate that the affinity between cyclobutrifluram and FfSdhs obviously decreased after point mutations, causing the resistance of F. fujikuroi.

Cyclobutrifluram is a novel succinate dehydrogenase inhibitor (SDHI) developed by Syngenta and helps to inhibit Fusarium pseudograminearum. Here, the potential for cyclobutrifluram resistance in F. pseudograminearumand the resistance mechanism involved were evaluated. Baseline sensitivity of F. pseudograminearumto cyclobutrifluram was determined with a mean EC50value of 0.0248 μg/mL. Fungicide adaption generated five resistant mutants, which possess a comparable or a slightly impaired fitness compared to corresponding parental isolates. This indicates that the resistance risk of F. pseudograminearumto cyclobutrifluram might be moderate. Cyclobutrifluram-resistant isolates also demonstrated resistance to pydiflumetofen but sensitivity to carbendazim, phenamacril, tebuconazole, fludioxonil, or pyraclostrobin. Additionally, point mutations H248Y in FpSdhB and A83V or R86K in FpSdhC1were found in cyclobutrifluram-resistant F. pseudograminearummutants. Molecular docking and overexpression transformation assay revealed that FpSdhBH248Yand FpSdhC1A83Vor FpSdhC1R86Kconfer the resistance of F. pseudograminearumto cyclobutrifluram.

Trans-cycloalkenes are abundant in bioactive natural products and have been used as powerful tools in chemical biology and drug discovery. However, strategies for the modular synthesis of trans-cycloalkenes, especially planar-chiral medium-sized ones, with high efficiency and selectivity, still remain elusive. Herein, we report a Pd-catalyzed asymmetric [7 + 2] cyclization strategy to address this challenge. As a result, two types of planar-chiral trans-cyclononenes bearing all-carbon chiral quaternary stereocenters are produced in up to 85% yield, >99% ee, and >19:1 dr (42 examples). The key to this success is the maintenance of the trans-2H configuration of the π-allyl-Pd species along with unusual linear selectivity during the H-bond-assisted cyclization process. In addition, the conversion of planar chirality to central chirality and its application in selective bioimaging of cancer cells via a bioorthogonal reaction were performed to demonstrate the synthetic value of this methodology.

Flexible on-skin electronics present tremendous popularity in intelligent electronic skins (e-skins), healthcare monitoring, and human-machine interfaces. However, the reported e-skins can hardly provide high permeability, good stretchability, and large sensitivity and are limited in long-term stability and efficient recyclability when worn on the human body. Herein, inspired from the human skin, a permeable, stretchable, and recyclable cellulose aerogel-based electronic system is developed by sandwiching a screen-printed silver sensing layer between a biocompatible CNF/HPC/PVA (cellulose nanofiber/hydroxypropyl cellulose/poly(vinyl alcohol)) aerogel hypodermis layer and a permeable polyurethane layer as the epidermis layer. The cellulose aerogel displays a high tensile strength of 1.14 MPa and tensile strain of 43.5% while maintaining good permeability. The cellulose aerogel-based electronics embrace appealing sensing performances with high sensitivity (gauge factor ≈ 238), ultralow detection limit (0.1%), and fast response time (18 ms) under strain stimulus. Owing to the disconnection and reconnection of microcracks in the sensing layer, both strain/humidity sensing and thermal healthcare can be easily achieved. The permeable electronics can be further integrated into an electronic mask for patient-centered healthcare with a power supply system, switching control device, and wireless Bluetooth module. Moreover, the prepared electronic system enables long-term wearing on human skin without skin irritation, and all components of the electronics can be recaptured/reused in water. This material strategy highlights the potential of next-generation on-skin electronics with high permeability and good environmental friendliness.

RNA 5-methylcytosine (m5C) is a widespread modification and plays a crucial role in gene expression regulation. Here, we present a protocol for transcriptome-wide m5C methylomes profiling at base-resolution using bisulfite-free m5Cdetection strategy enabled by TET-assisted chemical labeling (m5C-TAC-seq). We detail steps for TET-assisted chemical labeling, library construction, and data analysis. m5C-TAC-seq enables accurate and robust m5C detection in various RNA species. For complete details on the use and execution of this protocol, please refer to Lu et al.1

Nanoplastics pose a great threat to ecological water environments, especially for ocean water, lake water. Small-sized nanoplastic particles can enter into animal and plant bodies easily. Therefore, operando on-line quantification of nanoplastics in real environmental samples can bring a big challenge for early-stage water pollution testing and warning. Conventional nanoplastic particles detection technologies didn’t provide enough high sensitivity and accuracy due to their complicated and time-consuming sample pre-treatment procedures. To overcome these limitations, an optical microfiber was applied to detect nanoplastics in some real environmental samples. Owing to high sensitivity and superior specificity of the sensor, it could detect target polystyrene (PS) nanoplastics with sizes of 150 nm and 100 nm in pure water and mixture solution, realizing ultra-low limit-of-detections (LODs) of 1.23×10−6mg/mL, 1.41×10−6mg/mL and 2.31×10−6mg/mL, 2.96×10−6mg/mL, respectively. More importantly, such an optical device could also successfully recognize PS nanoplastics in collected lake, ocean, and wastewater samples. Thus, our proposed approach could open up a novel and advantageous way for operando on-line monitoring of nanoplastics in real water samples.

Concise synthesis of eight-membered lactones, a kind of medium-sized heterocycles widespread in many bioactive natural products, is highly significant. However, it still remains a challenge due to unfavorable entropic factor and transannular interaction. Herein, we disclose an enantioselective synthesis of eight-membered lactones through a Pd-catalyzed asymmetric (6 +2) dipolar annulation of vinyl oxetanes and α-diazo ketones (20 examples, up to 93% yield and 95:5 er). This reaction features simple operation, mild conditions and good enantiocontrol, especially the challenging chiral all-carbon quaternary stereocenter. A newly developed chiral hybrid P,S ligand and the in-situphoto-generation of ketene dipolarophiles are crucial to this success.

Searching for efficient strategies to access structurally novel aminoindolines is of great significance for drug discovery. However, catalytic asymmetric de novo construction of aminoindoline scaffolds with functionality primed for diversification still remains elusive. Here, we report a Cu-catalyzed asymmetric cyclization of ethynyl benzoxazinones with amines, producing chiral 3-aminoindolines in good yield and with high enantioselectivity (up to 97% yield and 98:2 er). Moreover, a radical-mediated sulfonyl migration of these products was unexpectedly found, further affording new chiral 3-aminoindolines bearing alkenyl sulfonyl groups with retained enantiopurity (up to 84% yield and 98:2 er). Bioactivity evaluations indicate that these 3-aminoindolines show notable antitumor activities and chirality is proven to have a significant impact on their antitumor activity.

With the gradual expansion of the grid-connected scale of new energy sources, and due to the inherent characteristics of new energy, a single type of new energy connecting to the grid has brought many problems to the power system, such as power grid instability, insufficient new energy accommodation, etc. Therefore, an integrated location and capacity coordination planning scheme for the multi-power complementary generation system is investigated in this paper to solve these problems. Firstly, the multi-power complementary generation system including wind power, photovoltaic, hydropower, thermal power, energy storage is introduced, and then the output power of various energy sources in the studied system is modeled. Secondly, a two-layer coordination optimization model is proposed considering simultaneous optimization of location and capacity, in which the upper layer optimizes the capacity and the lower layer optimizes the location. Besides, the K-means clustering algorithm is employed to reduce the large-scale scene to extract the typical scene, which can reduce computation burden and the impact of data uncertainty. Finally, the simulation is carried out based on the IEEE 39-bus system, and simulation results show that the proposed integrated location and capacity coordination planning scheme can achieve good complementarity between multiple energy sources in the studied system, and improve renewable energy absorption capacity and load absorption capacity.

To investigate the impact of uncertain variability and provide a rigorous testing environment for converter-dominated power systems, this article develops a testing tool called stochastic electromagnetic transient simulation. The tool is derived from the stochastic differential equation (SDE) representing the stochastic process of parameter migration. By inheriting the principle of companion circuit, the dynamic companion circuits of the lumped elements with parameter migration are further established. Combined with the analysis of the numerical stability in discrete simulation as well as the stability of the continuous system with parameter migration, a numerical algorithm that is compatible with the electromagnetic transients program (EMTP) framework is designed, as well as a C program package. The verification results on a grid-connected three-phase two-level rectifier and a two-terminal dc distribution system demonstrate that the developed tool can simulate the parameter migrations and the stimulated system dynamic process simultaneously, which can also be used to efficiently reflect the real performance of various control subsystems and their coordination in extreme cases.