Background Cotton is an important crop providing the most natural fibers all over the world. The cotton genomics community has utilized whole genome sequencing data to construct an elite gene pool in which functional ...Background Cotton is an important crop providing the most natural fibers all over the world. The cotton genomics community has utilized whole genome sequencing data to construct an elite gene pool in which functional genes are related to agronomic traits. However, the functional validation of these genes is hindered by time-consuming and inefficient genetic transformation methods. Thus, establishing a transient transformation system of high efficiency is necessary for cotton genomics.Results To improve the efficiency of transient transformation, we used the protoplasts isolated from the etiolated cotyledon as recipient. The enzymatic digestion buffer comprised 1.5%(w/v) cellulase, 0.75%(w/v) macerozyme, and 1% hemicellulase, osmotically buffered with 0.4 mol·L^(-1) mannitol. After 5 h of dark incubation at 25℃, uniform cotton protoplasts were successfully isolated with a yield of 4.6 × 10^(6) protoplasts per gram(fresh weight) and 95% viability. We incubated 100 μL protoplasts(2.5 × 10^(5)·m L^(-1)) with 15 μg plasmid in the solution of 0.4 mol·L^(-1) mannitol and 40% PEG 4000 for 15 min, ultimately achieving an optimal transient transfection efficiency of 71.47%.Conclusions This transient system demonstrated effective utility in cellular biology research through successful applications in subcellular localization analyses, bimolecular fluorescence complementation(Bi FC) verification, and prime editing vector validation. Through systematic optimization, we established an efficient and expedited protoplast-based transient transformation system and successfully applied this platform to cotton functional genomics studies.展开更多
This review comprehensively explores the theory and applications of attosecond transient absorption spectroscopy(ATAS)in studying ultrafast electronic dynamics across various systems,from atoms to solids.Driven by sig...This review comprehensively explores the theory and applications of attosecond transient absorption spectroscopy(ATAS)in studying ultrafast electronic dynamics across various systems,from atoms to solids.Driven by significant advancements in ultrafast laser technology,such as generating isolated attosecond pulses,ATAS enables detailed investigations of ultrafast electronic processes with unprecedented time resolution.The article introduces the fundamental principles and historical development of ATAS.Applications of ATAS are discussed in three main domains:in atoms,where it has been used to study build-up dynamics of Autler–Townes splitting,Fano resonance,light-induced states,etc.;in molecules,where it has revealed coherent molecular wavepacket dynamics and non-adiabatic dynamics near conical intersections;and in solids,where it has been extended to investigate ultrafast charge carrier dynamics in metals,semiconductors,and insulators.The review highlights the potential of ATAS in developing ultrafast optical switches and petahertz electronics.The ability of ATAS to probe and manipulate electronic dynamics at the attosecond timescale provides a powerful tool for exploring the fundamental limits of electronic and optical processes in materials.展开更多
The traditional detailed model of the dual active bridge(DAB)power electronic transformer is characterized by the high dimensionality of its nodal admittance matrix and the need for a small simulation step size,which ...The traditional detailed model of the dual active bridge(DAB)power electronic transformer is characterized by the high dimensionality of its nodal admittance matrix and the need for a small simulation step size,which limits the speed of electromagnetic transient(EMT)simulations.To overcome these limitations,a novel EMT equivalent model based on a generalized branch-cutting method is proposed to improve the simulation efficiency of the DAB model.The DAB topology is first decomposed into two subnetworks through branch-cutting and node-tearing methods without the introduction of a one-time-step delay.Sub-sequently,the internal nodes of each sub-network are eliminated through network simplification,and the equivalent circuit for the port cascade module is derived.The model is then validated through simulations across various operating conditions.The results demonstrate that the model avoids the loss of accuracy associated with one-time-step delay,the relative error across different conditions remains below 1%,and the simulation acceleration ratios improve as the number of modules increases.展开更多
The attosecond extreme ultraviolet(XUV) pulse pump and femtosecond infrared(IR) pulse probe scheme is commonly used to study the dynamics and attosecond transient absorption(ATA) spectra of microscopic systems. In a r...The attosecond extreme ultraviolet(XUV) pulse pump and femtosecond infrared(IR) pulse probe scheme is commonly used to study the dynamics and attosecond transient absorption(ATA) spectra of microscopic systems. In a recent report [Proc. Natl. Acad. Sci. USA 121 e2307836121(2024)], we showed that shaped XUV pulses with spectral minima can significantly alter the absorption line shape of helium's 2s2p doubly excited state within a few tens of attoseconds.However, it remains unclear if similar effects could be observed in a singly excited state. In this study, we use shaped XUV pulses to excite helium's 2p singly excited state and couple the 2p and 3d states with a delayed IR pulse. Comparing these results with those from Gaussian XUV pulses, we find that the ATA spectra for the shaped XUV pulses exhibit more pronounced changes with delay, while the changes for the Gaussian pulses are gradual. We also explain these differences through population changes and analytical models. Our findings show that shaped XUV pulses can regulate the dynamics and absorption spectra of a singly excited state.展开更多
We introduce a time-dependent generalized Floquet(TDGF)approach to calculate attosecond transient absorption spectra of helium atoms subjected to the combination of an attosecond extreme ultraviolet(XUV)pulse and a de...We introduce a time-dependent generalized Floquet(TDGF)approach to calculate attosecond transient absorption spectra of helium atoms subjected to the combination of an attosecond extreme ultraviolet(XUV)pulse and a delayed few-cycle infrared(IR)laser pulse.This TDGF approach provides a Floquet understanding of the laser-induced change of resonant absorption lineshape.It is analytically demonstrated that the phase shift of the time-dependent dipole moment that results in the lineshape changes consists of two components,the adiabatic laser-induced phase(LIP)due to the IR-induced Stark shifts of adiabatic Floquet states and the non-adiabatic phase correction due to the non-adiabatic IR-induced coupling between adiabatic Floquet states.Comparisons of the spectral lineshape calculated based on the TDGF approach with the results obtained with the LIP model[Phys.Rev.A 88033409(2013)]and the rotating-wave approximation(RWA)are presented for several typical cases,demonstrating that TDGF universally and accurately captures IR-induced lineshape changes.It is suggested that the LIP model works as long as the generalized adiabatic theorem[PRX Quantum 2030302(2021)]holds,and the RWA works when the higher-order IR-coupling effect in the formation of adiabatic Floquet states is neglectable.展开更多
Hydraulic fracturing and commingle production of multiple layers are extensively adopted in unconventional tight gas reservoirs.Accurate determination of parameters of individual layers in multilayered tight gas reser...Hydraulic fracturing and commingle production of multiple layers are extensively adopted in unconventional tight gas reservoirs.Accurate determination of parameters of individual layers in multilayered tight gas reservoirs is essential for well performance evaluation and development strategy optimization.However,most analytical models for fractured vertical wells in stratified gas reservoirs focus on fully penetrated hydraulic fractures,neglecting the influence of partial penetration of hydraulic fractures.This paper presents a semi-analytical model to investigate the transient pressure behavior of vertically fractured wells in dual porosity multi-layered tight gas reservoirs.The partial penetration of hydraulic fracture,the vertical heterogeneities of layer properties,the differences between hydraulic fracture lengths in each layer and the stress sensitivity are all incorporated in the proposed model.The point-source solution,Laplace transformation,Fourier transformation,Pedrosa's transformation,perturbation technique,and the superposition principle are applied to obtain the analytical solution of transient pressure responses.The proposed model is validated against a commercial software,and the transient pressure behavior of vertically fractured wells in multi-layered tight gas reservoirs are analyzed.Based on the characteristics of the type curves,seven flow regimes can be identified,including wellbore storage,transitional flow period,reservoir linear flow period,vertical pseudo-radial flow in fracture system,inter-porosity flow period,late-time pseudo-radial flow period,and the boundary-dominated flow period.Sensitivity analyses reveal that the penetration ratio of hydraulic fracture has primary influence on early-time transient pressure behavior and production contribution,while the stress sensitivity mainly affects the late-time transient pressure behavior.Gas production at the initial stage is mainly contributed by the high-pressure/high-permeability layer,and gas backflow will occur during initial production stage for obviously unequal initial formation pressures.Finally,two field cases are conducted to illustrate the applicability of the proposed model.The model and corresponding conclusions can provide technical support for performance analysis of tight gas reservoirs.展开更多
BACKGROUND There is insufficient evidence on the evaluation of liver fibrosis in Asian indivi-duals with primary biliary cholangitis(PBC)using vibration-controlled transient elastography(VCTE).AIM To assess advanced f...BACKGROUND There is insufficient evidence on the evaluation of liver fibrosis in Asian indivi-duals with primary biliary cholangitis(PBC)using vibration-controlled transient elastography(VCTE).AIM To assess advanced fibrosis(AF)using liver stiffness measurement(LSM)in Chinese patients with PBC.METHODS In total,277 Chinese patients diagnosed with PBC who underwent liver biopsy and VCTE were retrospectively included and categorized into the derivation and validation cohorts.The areas under the receiver operating characteristic curves(AUROCs)with 95%confidence intervals(CIs)were used to estimate the dia-gnostic accuracy of LSM for AF(Ludwig stage≥III).Multivariable analysis was performed using logistic regression.RESULTS In the derivation cohort,VCTE accurately detected patients with AF,achieving an AUROC of 0.93(95%CI:0.88-0.96).AF was independently predicted by LSM according to multivariable analysis.AF can be excluded and confirmed using LSM cutoffs of≤10.0 and>14.5 kPa,respectively,with a sensitivity of 0.91,negative predictive value of 0.93,specificity of 0.96,positive predictive value of 0.92,and an error rate of 7.5%.The accuracy of these values was validated in an independent cohort,achieving an AUROC of 0.97(95%CI:0.90-0.99)for AF with a sensitivity of 0.89,negative predictive value of 0.88,specificity of 0.95,positive predictive value of 0.94,and error rate of 9.0%.Compared with serum fibrosis markers,the AUROC of LSM was significantly higher in both the derivation and validation cohorts.CONCLUSION VCTE has a high accuracy for assessing AF in Chinese patients with PBC in a real-world setting.展开更多
The Agrobacterium-mediated transient expression system with conventional binary vectors is well established in tobacco leaves,while the same system applied to tomato leaflets has relatively low expression efficiency.H...The Agrobacterium-mediated transient expression system with conventional binary vectors is well established in tobacco leaves,while the same system applied to tomato leaflets has relatively low expression efficiency.However,impacts of the leaf age,inoculation method and incubation condition after Agrobacterium infiltration on transient protein expression efficiency are seldom investigated.In this study,we optimize Agrobacterium-mediated transient expression system using conventional binary vectors to achieve the high efficiency of target gene expression in tomato leaflets.We transiently express GFP and a nucleus-localized gene SlUVI4 fused with GFP in detached 10-,20-,and 30-day-old leaflets.The cutting points of leaflets are embedded in MS medium after the Agrobacterium-mediated vacuum infiltration,and all leaflets are kept in the dark before use.The 10-and 30-day-old leaflets have more damage than 20-day-old leaflets after the infiltration.展开更多
As the penetration rate of distributed energy increases,the transient power angle stability problem of the virtual synchronous generator(VSG)has gradually become prominent.In view of the situation that the grid impeda...As the penetration rate of distributed energy increases,the transient power angle stability problem of the virtual synchronous generator(VSG)has gradually become prominent.In view of the situation that the grid impedance ratio(R/X)is high and affects the transient power angle stability of VSG,this paper proposes a VSG transient power angle stability control strategy based on the combination of frequency difference feedback and virtual impedance.To improve the transient power angle stability of the VSG,a virtual impedance is adopted in the voltage loop to adjust the impedance ratio R/X;and the PI control feedback of the VSG frequency difference is introduced in the reactive powervoltage link of theVSGto enhance the damping effect.Thesecond-orderVSGdynamic nonlinearmodel considering the reactive power-voltage loop is established and the influence of different proportional integral(PI)control parameters on the system balance stability is analyzed.Moreover,the impact of the impedance ratio R/X on the transient power angle stability is presented using the equal area criterion.In the simulations,during the voltage dips with the reduction of R/X from 1.6 to 0.8,Δδ_(1)is reduced from 0.194 rad to 0.072 rad,Δf_(1)is reduced from 0.170 to 0.093 Hz,which shows better transient power angle stability.Simulation results verify that compared with traditional VSG,the proposedmethod can effectively improve the transient power angle stability of the system.展开更多
The forward modeling procedure used in this article is formulated with the volume integral equation based on the tensor Green＇s function. The electromagnetic components responses are first calculated in the frequency...The forward modeling procedure used in this article is formulated with the volume integral equation based on the tensor Green＇s function. The electromagnetic components responses are first calculated in the frequency domain and then transformed to the time domain by digital filtering. The valley and hill topography with a layered earth is stimulated by a horizontal electric dipole （HED） transmitter, which is common in field surveys, and the TEM responses are calculated at the transmitter and receivers. The topography effects on the long offset electromagnetic transient （LOTEM） responses are discussed in detail. The results show that both valley and hill topography has significant effect on the LOTEM measurement. If the HED is located in the bottom of a valley, the distortion of the observed anomalous field at distance is severe. A valley at the receiver locations show a strong effect but are localized in space and time. In general, hill-shaped topography shows smaller effects no matter where its located. When the topography is located between source and receivers, the influence is negligible. We conclude that the location of the source is much more important than the receivers and it is critical to put the transmitter in an open flat area in the field survey.展开更多
We calculate the multicomponent responses of surface-hole transient electromagnetic method. The methods and models are unsuitable as geoelectric models of conductive surrounding rocks because they are based on regular...We calculate the multicomponent responses of surface-hole transient electromagnetic method. The methods and models are unsuitable as geoelectric models of conductive surrounding rocks because they are based on regular local targets. We also propose a calculation and analysis scheme based on numerical simulations of the subsurface transient electromagnetic fields. In the modeling of the electromagnetic fields, the forward modeling simulations are performed by using the finite-difference time-domain method and the discrete image method, which combines the Gaver–Stehfest inverse Laplace transform with the Prony method to solve the initial electromagnetic fields. The precision in the iterative computations is ensured by using the transmission boundary conditions. For the response analysis, we customize geoelectric models consisting of near-borehole targets and conductive wall rocks and implement forward modeling simulations. The observed electric fields are converted into induced electromotive force responses using multicomponent observation devices. By comparing the transient electric fields and multicomponent responses under different conditions, we suggest that the multicomponent-induced electromotive force responses are related to the horizontal and vertical gradient variations of the transient electric field at different times. The characteristics of the response are determined by the varying the subsurface transient electromagnetic fields, i.e., diffusion, attenuation and distortion, under different conditions as well as the electromagnetic fields at the observation positions. The calculation and analysis scheme of the response consider the surrounding rocks and the anomalous field of the local targets. It therefore can account for the geological data better than conventional transient field response analysis of local targets.展开更多
The single event transient effects of the operational amplifier LM124J and the optocoupler HCPL 5231 are investigated by a pulsed laser test facility. The relation of transient pulse shape to pulsed laser equivalent L...The single event transient effects of the operational amplifier LM124J and the optocoupler HCPL 5231 are investigated by a pulsed laser test facility. The relation of transient pulse shape to pulsed laser equivalent LET is tested,the sensitive areas of the SET effects are identified in voltage follower application mode of LM124J, and the mechanism is initially analyzed. The transient amplitude and duration of HCPL5231 at various equivalent LET are examined,and the SET cross-section is measured. The results of our test and heavy ion experimental data coincide closely,indicating that a pulsed laser test facility is a valid tool for single event effect evaluation.展开更多
This study examines the influence of magnetic field and temperature on the transient voltage of a polycrystalline silicon radial junction solar cell in a dynamic regime under multispectral illumination. Radial junctio...This study examines the influence of magnetic field and temperature on the transient voltage of a polycrystalline silicon radial junction solar cell in a dynamic regime under multispectral illumination. Radial junction solar cells represent a major advancement in photovoltaic technologies, as they optimize light absorption and charge collection efficiency. The focus is on the impact of the magnetic field and temperature on the decay of transient voltage, which provides crucial information on recombination processes and the lifetime of minority carriers. The results reveal that the magnetic field tends to increase the transient voltage by directly affecting the transient electron density. Indeed, for B > 7 × 10−5 T, the magnetic field prolongs the relaxation time by increasing the transient voltage amplitude. Additionally, rising temperatures accelerate (ranging from 290 K to 450 K) recombination processes, thereby reducing the transient voltage, although this effect is moderated by the presence of a magnetic field. The study highlights the complex interaction between magnetic field and temperature, with significant impacts on the transient behaviour.展开更多
To effectively minimize the electromagnetic field response in the total field solution, we propose a numerical modeling method for the two-dimensional （2D） time- domain transient electromagnetic secondary field of t...To effectively minimize the electromagnetic field response in the total field solution, we propose a numerical modeling method for the two-dimensional （2D） time- domain transient electromagnetic secondary field of the line source based on the DuFort- Frankel finite-difference method. In the proposed method, we included the treatment of the earth-air boundary conductivity, calculated the normalized partial derivative of the induced electromotive force （Emf）, and determined the forward time step. By extending upward the earth-air interface to the air grid nodes and the zero-value boundary conditions, not only we have a method that is more efficient but also simpler than the total field solution. We computed and analyzed the homogeneous half-space model and the fiat layered model with high precision--the maximum relative error is less than 0.01% between our method and the analytical method--and the solution speed is roughly three times faster than the total-field solution. Lastly, we used the model of a thin body embedded in a homogeneous half-space at different delay times to depict the downward and upward spreading characteristics of the induced eddy current, and the physical interaction processes between the electromagnetic field and the underground low-resistivity body.展开更多
Panax Ginseng(2n=48)represents a quintessential resource in traditional Chinese medicine,renowned for its outstanding medicinal and economic benefits(Choi,2008).But the late start in analyzing the ginseng genome and t...Panax Ginseng(2n=48)represents a quintessential resource in traditional Chinese medicine,renowned for its outstanding medicinal and economic benefits(Choi,2008).But the late start in analyzing the ginseng genome and the poorly developed genetic transformation system still impede the study of ginseng gene function and the application of molecular breeding.Transient transformation has the advantages of high efficiency,low cost,and short cycle while laying the foundation for stable genetic transformation(Chen et al.,2021).In the plant transformation process,the cell wall prevents exogenous DNA or protein entry,significantly reducing the efficiency of the transformation.Protoplasts,as exposed cells wrapped by the plasma membrane,are more likely to absorb exogenous DNA,RNA,and protein.Transgenic systems of protoplasts have been established in several species and applied in many fields,such as gene function research(Gou et al.,2020),gene editing(Yang et al.,2023),and physiological or molecular mechanism research(Aoyagi,2011).For instance,Oryza sativa protoplasts were employed to screen genes involved in rice defense signaling pathways through fluorescent reporter systems,with BiFC employed to verified inter-protein interactions(He et al.,2016).A study transformed Cannabis sativa L.protoplasts with the plasmids carrying GFP and RFP genes,evaluated the efficiency under different transformation conditions by flow cytometry,and verified the induction of synthetic DR5 promoter by IAA based on the constructed system(Beard et al.,2021).展开更多
We conducted a study on the numerical calculation and response analysis of a transient electromagnetic field generated by a ground source in geological media. One solution method, the traditional discrete image method...We conducted a study on the numerical calculation and response analysis of a transient electromagnetic field generated by a ground source in geological media. One solution method, the traditional discrete image method, involves complex operation, and its digital filtering algorithm requires a large number of calculations. To solve these problems, we proposed an improved discrete image method, where the following are realized： the real number of the electromagnetic field solution based on the Gaver-Stehfest algorithm for approximate inversion, the exponential approximation of the objective kernel function using the Prony method, the transient electromagnetic field according to discrete image theory, and closed-form solution of the approximate coefficients. To verify the method, we tentatively calculated the transient electromagnetic field in a homogeneous model and compared it with the results obtained from the Hankel transform digital filtering method. The results show that the method has considerable accuracy and good applicability. We then used this method to calculate the transient electromagnetic field generated by a ground magnetic dipole source in a typical geoelectric model and analyzed the horizontal component response of the induced magnetic field obtained from the ＂ground excitation-stratum measurement method. We reached the conclusion that the horizontal component response of a transient field is related to the geoelectric structure, observation time, spatial location, and others. The horizontal component response of the induced magnetic field reflects the eddy current field distribution and its vertical gradient variation. During the detection of abnormal objects, positions with a zero or comparatively large offset were selected for the drill- hole measurements or a comparatively long observation delay was adopted to reduce the influence of the ambient field on the survey results. The discrete image method and forward calculation results in this paper can be used as references for relevant research.展开更多
Transient electronics is a versatile tool that finds applications in various fields,including medical biology,environmental protection,and data information security.In the context of data protection,the traditional pa...Transient electronics is a versatile tool that finds applications in various fields,including medical biology,environmental protection,and data information security.In the context of data protection,the traditional passive degradation transient mode is being replaced by the active destruction mode,which features a short self-destruction time and provides greater resistance to recovery.This article presents an overview of recent progress in transient electronics,assessing the benefits and suitability of varying transient mechanisms.The article also analyses the influence of transient electronics on military security while emphasizing the advantages of implementing energetic materials.Besides,the article introduces energetic transient devices and evaluates their ability to support the autonomous operation of transient electronic devices.展开更多
A nickel-catalyzed C(sp^(2))–H alkynylation of unprotected α-substituted benzylamines is achieved by utilizing a transient directing group. The combination of a TDG with a nickel catalyst significantly improves the ...A nickel-catalyzed C(sp^(2))–H alkynylation of unprotected α-substituted benzylamines is achieved by utilizing a transient directing group. The combination of a TDG with a nickel catalyst significantly improves the reaction step and atom economy. It has been investigated that the 2,4,6-trimethylpyridine ligand was critical to achieve the optimized reactivity. This protocol provides a straightforward route for synthesizing the alkynylated free benzylamines, featuring good substrate compatibility and monoselectivity.展开更多
Transient negative capacitance(NC),as an available dynamic charge effect achieved in resistor-ferroelectric capacitor(R-FEC)circuits,has triggered a series of theoretical and experimental works focusing on its physica...Transient negative capacitance(NC),as an available dynamic charge effect achieved in resistor-ferroelectric capacitor(R-FEC)circuits,has triggered a series of theoretical and experimental works focusing on its physical mechanism and device application.Here,we analytically derived the effects of different mechanical conditions on the transient NC behaviors in the R-FEC circuit based on the phenomenological model.It shows that the ferroelectric capacitor can exhibit either NC(i.e.,“single NC”and“double NC”)or positive capacitance,depending on the mechanical condition and temperature.Further numerical calculations show that the voltage drop caused by NC can be effectively controlled by temperature,applied stress,or strain.The relationship between NC voltage drop and system configurations including external resistance,dynamical coefficient of polarization,and input voltage are presented,showing diverse strategies to manipulate the NC effect.These results provide theoretical guidelines for rational design and efficient control of NC-related electronic devices.展开更多
A pre-swirl system with a multi-chamber structure is crucial to the secondary air system of an aero engine.The airflow within the pre-swirl system(characterized by high-speed rotation and compressible flow)is complica...A pre-swirl system with a multi-chamber structure is crucial to the secondary air system of an aero engine.The airflow within the pre-swirl system(characterized by high-speed rotation and compressible flow)is complicated.During transient processes in aero engine operation,the pre-swirl system is subjected to upstream fluctuations,which is a less studied aspect.This paper delves into the unsteady flow characteristics within the pre-swirl system.We investigate the influence of different pressure-fluctuation boundary conditions,corresponding to step function,ramp function,and sine function,on the transient response characteristics of the pre-swirl system.The results indicate that the response characteristics are strongly affected by the upstream boundary conditions.An obvious overshoot phenomenon is observed in the actual temperature drop under the step and ramp function conditions.The peak time of the step function is 75%shorter compared to the ramp function.Furthermore,the flow parameters exhibit nonlinear growth during the transient process,emphasizing the need for consideration in future quasi-steady simulations.For the sine function condition,the pressure-fluctuation frequency minimally affects stable values of mass flow rate and actual temperature drop but exerts a substantial influence on the maximum deviation of actual temperature drop of the system.As the frequency increases from 100 Hz to 200 Hz,the maximum deviations for actual temperature drop change from around±13 K to±10 K.展开更多
基金supported by Biological Breeding of Early Maturing and Disease Resistant Cotton Varieties (NO.2023ZD04041)the Project of China Agriculture Research System (Grant No. CARS-15-06)+2 种基金Natural Science Foundation of Henan Province (Grant No. 232300421041 and 222300420382)National Natural Science Foundation of China (Grant No. U21 A20213)the Central Public-interest Scientific Institution Basal Research Fund (Grant No. 1610162023017 and 1610162023028)。
文摘Background Cotton is an important crop providing the most natural fibers all over the world. The cotton genomics community has utilized whole genome sequencing data to construct an elite gene pool in which functional genes are related to agronomic traits. However, the functional validation of these genes is hindered by time-consuming and inefficient genetic transformation methods. Thus, establishing a transient transformation system of high efficiency is necessary for cotton genomics.Results To improve the efficiency of transient transformation, we used the protoplasts isolated from the etiolated cotyledon as recipient. The enzymatic digestion buffer comprised 1.5%(w/v) cellulase, 0.75%(w/v) macerozyme, and 1% hemicellulase, osmotically buffered with 0.4 mol·L^(-1) mannitol. After 5 h of dark incubation at 25℃, uniform cotton protoplasts were successfully isolated with a yield of 4.6 × 10^(6) protoplasts per gram(fresh weight) and 95% viability. We incubated 100 μL protoplasts(2.5 × 10^(5)·m L^(-1)) with 15 μg plasmid in the solution of 0.4 mol·L^(-1) mannitol and 40% PEG 4000 for 15 min, ultimately achieving an optimal transient transfection efficiency of 71.47%.Conclusions This transient system demonstrated effective utility in cellular biology research through successful applications in subcellular localization analyses, bimolecular fluorescence complementation(Bi FC) verification, and prime editing vector validation. Through systematic optimization, we established an efficient and expedited protoplast-based transient transformation system and successfully applied this platform to cotton functional genomics studies.
基金Project supported by the National Natural Science Foundation of China(Grant No.12174034)。
文摘This review comprehensively explores the theory and applications of attosecond transient absorption spectroscopy(ATAS)in studying ultrafast electronic dynamics across various systems,from atoms to solids.Driven by significant advancements in ultrafast laser technology,such as generating isolated attosecond pulses,ATAS enables detailed investigations of ultrafast electronic processes with unprecedented time resolution.The article introduces the fundamental principles and historical development of ATAS.Applications of ATAS are discussed in three main domains:in atoms,where it has been used to study build-up dynamics of Autler–Townes splitting,Fano resonance,light-induced states,etc.;in molecules,where it has revealed coherent molecular wavepacket dynamics and non-adiabatic dynamics near conical intersections;and in solids,where it has been extended to investigate ultrafast charge carrier dynamics in metals,semiconductors,and insulators.The review highlights the potential of ATAS in developing ultrafast optical switches and petahertz electronics.The ability of ATAS to probe and manipulate electronic dynamics at the attosecond timescale provides a powerful tool for exploring the fundamental limits of electronic and optical processes in materials.
基金The Technology Project of State Grid Corporation of China Headquarters(No.5400-202318547A-3-2-ZN).
文摘The traditional detailed model of the dual active bridge(DAB)power electronic transformer is characterized by the high dimensionality of its nodal admittance matrix and the need for a small simulation step size,which limits the speed of electromagnetic transient(EMT)simulations.To overcome these limitations,a novel EMT equivalent model based on a generalized branch-cutting method is proposed to improve the simulation efficiency of the DAB model.The DAB topology is first decomposed into two subnetworks through branch-cutting and node-tearing methods without the introduction of a one-time-step delay.Sub-sequently,the internal nodes of each sub-network are eliminated through network simplification,and the equivalent circuit for the port cascade module is derived.The model is then validated through simulations across various operating conditions.The results demonstrate that the model avoids the loss of accuracy associated with one-time-step delay,the relative error across different conditions remains below 1%,and the simulation acceleration ratios improve as the number of modules increases.
基金Project supported by the National Natural Science Foundation of China (Grant No. 12274230)the Funding of Nanjing University of Science and Technology (Grant No. TSXK2022D005)。
文摘The attosecond extreme ultraviolet(XUV) pulse pump and femtosecond infrared(IR) pulse probe scheme is commonly used to study the dynamics and attosecond transient absorption(ATA) spectra of microscopic systems. In a recent report [Proc. Natl. Acad. Sci. USA 121 e2307836121(2024)], we showed that shaped XUV pulses with spectral minima can significantly alter the absorption line shape of helium's 2s2p doubly excited state within a few tens of attoseconds.However, it remains unclear if similar effects could be observed in a singly excited state. In this study, we use shaped XUV pulses to excite helium's 2p singly excited state and couple the 2p and 3d states with a delayed IR pulse. Comparing these results with those from Gaussian XUV pulses, we find that the ATA spectra for the shaped XUV pulses exhibit more pronounced changes with delay, while the changes for the Gaussian pulses are gradual. We also explain these differences through population changes and analytical models. Our findings show that shaped XUV pulses can regulate the dynamics and absorption spectra of a singly excited state.
基金supported by the National Natural Science Foundation of China(Grant Nos.W2411002 and 12375018).
文摘We introduce a time-dependent generalized Floquet(TDGF)approach to calculate attosecond transient absorption spectra of helium atoms subjected to the combination of an attosecond extreme ultraviolet(XUV)pulse and a delayed few-cycle infrared(IR)laser pulse.This TDGF approach provides a Floquet understanding of the laser-induced change of resonant absorption lineshape.It is analytically demonstrated that the phase shift of the time-dependent dipole moment that results in the lineshape changes consists of two components,the adiabatic laser-induced phase(LIP)due to the IR-induced Stark shifts of adiabatic Floquet states and the non-adiabatic phase correction due to the non-adiabatic IR-induced coupling between adiabatic Floquet states.Comparisons of the spectral lineshape calculated based on the TDGF approach with the results obtained with the LIP model[Phys.Rev.A 88033409(2013)]and the rotating-wave approximation(RWA)are presented for several typical cases,demonstrating that TDGF universally and accurately captures IR-induced lineshape changes.It is suggested that the LIP model works as long as the generalized adiabatic theorem[PRX Quantum 2030302(2021)]holds,and the RWA works when the higher-order IR-coupling effect in the formation of adiabatic Floquet states is neglectable.
基金supported by the National Natural Science Foundation of China(Grant Nos.52174036,52234003)the Sichuan Province Science and Technology Program(Grant No.2024NSFSC0199)the Joint Fund for Innovation and Development of Chongqing Natural Science Foundation(Grant No.2023NSCQ-LZX0184).
文摘Hydraulic fracturing and commingle production of multiple layers are extensively adopted in unconventional tight gas reservoirs.Accurate determination of parameters of individual layers in multilayered tight gas reservoirs is essential for well performance evaluation and development strategy optimization.However,most analytical models for fractured vertical wells in stratified gas reservoirs focus on fully penetrated hydraulic fractures,neglecting the influence of partial penetration of hydraulic fractures.This paper presents a semi-analytical model to investigate the transient pressure behavior of vertically fractured wells in dual porosity multi-layered tight gas reservoirs.The partial penetration of hydraulic fracture,the vertical heterogeneities of layer properties,the differences between hydraulic fracture lengths in each layer and the stress sensitivity are all incorporated in the proposed model.The point-source solution,Laplace transformation,Fourier transformation,Pedrosa's transformation,perturbation technique,and the superposition principle are applied to obtain the analytical solution of transient pressure responses.The proposed model is validated against a commercial software,and the transient pressure behavior of vertically fractured wells in multi-layered tight gas reservoirs are analyzed.Based on the characteristics of the type curves,seven flow regimes can be identified,including wellbore storage,transitional flow period,reservoir linear flow period,vertical pseudo-radial flow in fracture system,inter-porosity flow period,late-time pseudo-radial flow period,and the boundary-dominated flow period.Sensitivity analyses reveal that the penetration ratio of hydraulic fracture has primary influence on early-time transient pressure behavior and production contribution,while the stress sensitivity mainly affects the late-time transient pressure behavior.Gas production at the initial stage is mainly contributed by the high-pressure/high-permeability layer,and gas backflow will occur during initial production stage for obviously unequal initial formation pressures.Finally,two field cases are conducted to illustrate the applicability of the proposed model.The model and corresponding conclusions can provide technical support for performance analysis of tight gas reservoirs.
基金Supported by the Capital’s Funds for Health Improvement and Research,No.CFH2024-1-2173State Administration of Traditional Chinese Medicine High-Level Key Disciplines Construction Project,No.zyyzdxk-2023005the Scientific Research Fund Project of Beijing Ditan Hospital,No.DTDR202403.
文摘BACKGROUND There is insufficient evidence on the evaluation of liver fibrosis in Asian indivi-duals with primary biliary cholangitis(PBC)using vibration-controlled transient elastography(VCTE).AIM To assess advanced fibrosis(AF)using liver stiffness measurement(LSM)in Chinese patients with PBC.METHODS In total,277 Chinese patients diagnosed with PBC who underwent liver biopsy and VCTE were retrospectively included and categorized into the derivation and validation cohorts.The areas under the receiver operating characteristic curves(AUROCs)with 95%confidence intervals(CIs)were used to estimate the dia-gnostic accuracy of LSM for AF(Ludwig stage≥III).Multivariable analysis was performed using logistic regression.RESULTS In the derivation cohort,VCTE accurately detected patients with AF,achieving an AUROC of 0.93(95%CI:0.88-0.96).AF was independently predicted by LSM according to multivariable analysis.AF can be excluded and confirmed using LSM cutoffs of≤10.0 and>14.5 kPa,respectively,with a sensitivity of 0.91,negative predictive value of 0.93,specificity of 0.96,positive predictive value of 0.92,and an error rate of 7.5%.The accuracy of these values was validated in an independent cohort,achieving an AUROC of 0.97(95%CI:0.90-0.99)for AF with a sensitivity of 0.89,negative predictive value of 0.88,specificity of 0.95,positive predictive value of 0.94,and error rate of 9.0%.Compared with serum fibrosis markers,the AUROC of LSM was significantly higher in both the derivation and validation cohorts.CONCLUSION VCTE has a high accuracy for assessing AF in Chinese patients with PBC in a real-world setting.
基金support of Taishan Scholar Foundation of Shandong Province(tsqn201909073,tsqn201812034)National Natural Science Foundation of China(31872951)。
文摘The Agrobacterium-mediated transient expression system with conventional binary vectors is well established in tobacco leaves,while the same system applied to tomato leaflets has relatively low expression efficiency.However,impacts of the leaf age,inoculation method and incubation condition after Agrobacterium infiltration on transient protein expression efficiency are seldom investigated.In this study,we optimize Agrobacterium-mediated transient expression system using conventional binary vectors to achieve the high efficiency of target gene expression in tomato leaflets.We transiently express GFP and a nucleus-localized gene SlUVI4 fused with GFP in detached 10-,20-,and 30-day-old leaflets.The cutting points of leaflets are embedded in MS medium after the Agrobacterium-mediated vacuum infiltration,and all leaflets are kept in the dark before use.The 10-and 30-day-old leaflets have more damage than 20-day-old leaflets after the infiltration.
基金supported by theMajor Science and Technology Projects of China Southern Power Grid(Grant number CGYKJXM20210328).
文摘As the penetration rate of distributed energy increases,the transient power angle stability problem of the virtual synchronous generator(VSG)has gradually become prominent.In view of the situation that the grid impedance ratio(R/X)is high and affects the transient power angle stability of VSG,this paper proposes a VSG transient power angle stability control strategy based on the combination of frequency difference feedback and virtual impedance.To improve the transient power angle stability of the VSG,a virtual impedance is adopted in the voltage loop to adjust the impedance ratio R/X;and the PI control feedback of the VSG frequency difference is introduced in the reactive powervoltage link of theVSGto enhance the damping effect.Thesecond-orderVSGdynamic nonlinearmodel considering the reactive power-voltage loop is established and the influence of different proportional integral(PI)control parameters on the system balance stability is analyzed.Moreover,the impact of the impedance ratio R/X on the transient power angle stability is presented using the equal area criterion.In the simulations,during the voltage dips with the reduction of R/X from 1.6 to 0.8,Δδ_(1)is reduced from 0.194 rad to 0.072 rad,Δf_(1)is reduced from 0.170 to 0.093 Hz,which shows better transient power angle stability.Simulation results verify that compared with traditional VSG,the proposedmethod can effectively improve the transient power angle stability of the system.
基金supported by National Natural Science Foundation of China (Nos. 40727001, 40774073, and 40774074)the National Basic Research Programs of China (973 Program) (No. 2007CB209607)the Doctoral Program of Higher Research and Special funds (No. 20070489001)
文摘The forward modeling procedure used in this article is formulated with the volume integral equation based on the tensor Green＇s function. The electromagnetic components responses are first calculated in the frequency domain and then transformed to the time domain by digital filtering. The valley and hill topography with a layered earth is stimulated by a horizontal electric dipole （HED） transmitter, which is common in field surveys, and the TEM responses are calculated at the transmitter and receivers. The topography effects on the long offset electromagnetic transient （LOTEM） responses are discussed in detail. The results show that both valley and hill topography has significant effect on the LOTEM measurement. If the HED is located in the bottom of a valley, the distortion of the observed anomalous field at distance is severe. A valley at the receiver locations show a strong effect but are localized in space and time. In general, hill-shaped topography shows smaller effects no matter where its located. When the topography is located between source and receivers, the influence is negligible. We conclude that the location of the source is much more important than the receivers and it is critical to put the transmitter in an open flat area in the field survey.
基金supported by the Young Scientists Fund of the National Natural Science Foundation of China(No.41304082)the China Postdoctoral Science Foundation(No.2016M590731)+2 种基金the Young Scientists Fund of the Natural Science Foundation of Hebei Province(No.D2014403011)the Program for Young Excellent Talents of Higher Education Institutions of Hebei Province(No.BJ2016046)the Geological survey project of China Geological Survey(No.1212011121197)
文摘We calculate the multicomponent responses of surface-hole transient electromagnetic method. The methods and models are unsuitable as geoelectric models of conductive surrounding rocks because they are based on regular local targets. We also propose a calculation and analysis scheme based on numerical simulations of the subsurface transient electromagnetic fields. In the modeling of the electromagnetic fields, the forward modeling simulations are performed by using the finite-difference time-domain method and the discrete image method, which combines the Gaver–Stehfest inverse Laplace transform with the Prony method to solve the initial electromagnetic fields. The precision in the iterative computations is ensured by using the transmission boundary conditions. For the response analysis, we customize geoelectric models consisting of near-borehole targets and conductive wall rocks and implement forward modeling simulations. The observed electric fields are converted into induced electromotive force responses using multicomponent observation devices. By comparing the transient electric fields and multicomponent responses under different conditions, we suggest that the multicomponent-induced electromotive force responses are related to the horizontal and vertical gradient variations of the transient electric field at different times. The characteristics of the response are determined by the varying the subsurface transient electromagnetic fields, i.e., diffusion, attenuation and distortion, under different conditions as well as the electromagnetic fields at the observation positions. The calculation and analysis scheme of the response consider the surrounding rocks and the anomalous field of the local targets. It therefore can account for the geological data better than conventional transient field response analysis of local targets.
文摘The single event transient effects of the operational amplifier LM124J and the optocoupler HCPL 5231 are investigated by a pulsed laser test facility. The relation of transient pulse shape to pulsed laser equivalent LET is tested,the sensitive areas of the SET effects are identified in voltage follower application mode of LM124J, and the mechanism is initially analyzed. The transient amplitude and duration of HCPL5231 at various equivalent LET are examined,and the SET cross-section is measured. The results of our test and heavy ion experimental data coincide closely,indicating that a pulsed laser test facility is a valid tool for single event effect evaluation.
文摘This study examines the influence of magnetic field and temperature on the transient voltage of a polycrystalline silicon radial junction solar cell in a dynamic regime under multispectral illumination. Radial junction solar cells represent a major advancement in photovoltaic technologies, as they optimize light absorption and charge collection efficiency. The focus is on the impact of the magnetic field and temperature on the decay of transient voltage, which provides crucial information on recombination processes and the lifetime of minority carriers. The results reveal that the magnetic field tends to increase the transient voltage by directly affecting the transient electron density. Indeed, for B > 7 × 10−5 T, the magnetic field prolongs the relaxation time by increasing the transient voltage amplitude. Additionally, rising temperatures accelerate (ranging from 290 K to 450 K) recombination processes, thereby reducing the transient voltage, although this effect is moderated by the presence of a magnetic field. The study highlights the complex interaction between magnetic field and temperature, with significant impacts on the transient behaviour.
基金supported by the National High Technology Research and Development Program (863 Program)(2009AA06Z108)
文摘To effectively minimize the electromagnetic field response in the total field solution, we propose a numerical modeling method for the two-dimensional （2D） time- domain transient electromagnetic secondary field of the line source based on the DuFort- Frankel finite-difference method. In the proposed method, we included the treatment of the earth-air boundary conductivity, calculated the normalized partial derivative of the induced electromotive force （Emf）, and determined the forward time step. By extending upward the earth-air interface to the air grid nodes and the zero-value boundary conditions, not only we have a method that is more efficient but also simpler than the total field solution. We computed and analyzed the homogeneous half-space model and the fiat layered model with high precision--the maximum relative error is less than 0.01% between our method and the analytical method--and the solution speed is roughly three times faster than the total-field solution. Lastly, we used the model of a thin body embedded in a homogeneous half-space at different delay times to depict the downward and upward spreading characteristics of the induced eddy current, and the physical interaction processes between the electromagnetic field and the underground low-resistivity body.
基金supported by the Genetic analysis of important quality and traits of ginseng and basic research on molecular design breeding(Grant No.U21A20405)。
文摘Panax Ginseng(2n=48)represents a quintessential resource in traditional Chinese medicine,renowned for its outstanding medicinal and economic benefits(Choi,2008).But the late start in analyzing the ginseng genome and the poorly developed genetic transformation system still impede the study of ginseng gene function and the application of molecular breeding.Transient transformation has the advantages of high efficiency,low cost,and short cycle while laying the foundation for stable genetic transformation(Chen et al.,2021).In the plant transformation process,the cell wall prevents exogenous DNA or protein entry,significantly reducing the efficiency of the transformation.Protoplasts,as exposed cells wrapped by the plasma membrane,are more likely to absorb exogenous DNA,RNA,and protein.Transgenic systems of protoplasts have been established in several species and applied in many fields,such as gene function research(Gou et al.,2020),gene editing(Yang et al.,2023),and physiological or molecular mechanism research(Aoyagi,2011).For instance,Oryza sativa protoplasts were employed to screen genes involved in rice defense signaling pathways through fluorescent reporter systems,with BiFC employed to verified inter-protein interactions(He et al.,2016).A study transformed Cannabis sativa L.protoplasts with the plasmids carrying GFP and RFP genes,evaluated the efficiency under different transformation conditions by flow cytometry,and verified the induction of synthetic DR5 promoter by IAA based on the constructed system(Beard et al.,2021).
基金supported by the Young Scientists Fund of the National Natural Science Foundation of China(No.41304082)the Young Scientists Fund of the Natural Science Foundation of Hebei Province(No.D2014403011)the Geological survey project of China Geological Survey(No.12120114090201)
文摘We conducted a study on the numerical calculation and response analysis of a transient electromagnetic field generated by a ground source in geological media. One solution method, the traditional discrete image method, involves complex operation, and its digital filtering algorithm requires a large number of calculations. To solve these problems, we proposed an improved discrete image method, where the following are realized： the real number of the electromagnetic field solution based on the Gaver-Stehfest algorithm for approximate inversion, the exponential approximation of the objective kernel function using the Prony method, the transient electromagnetic field according to discrete image theory, and closed-form solution of the approximate coefficients. To verify the method, we tentatively calculated the transient electromagnetic field in a homogeneous model and compared it with the results obtained from the Hankel transform digital filtering method. The results show that the method has considerable accuracy and good applicability. We then used this method to calculate the transient electromagnetic field generated by a ground magnetic dipole source in a typical geoelectric model and analyzed the horizontal component response of the induced magnetic field obtained from the ＂ground excitation-stratum measurement method. We reached the conclusion that the horizontal component response of a transient field is related to the geoelectric structure, observation time, spatial location, and others. The horizontal component response of the induced magnetic field reflects the eddy current field distribution and its vertical gradient variation. During the detection of abnormal objects, positions with a zero or comparatively large offset were selected for the drill- hole measurements or a comparatively long observation delay was adopted to reduce the influence of the ambient field on the survey results. The discrete image method and forward calculation results in this paper can be used as references for relevant research.
基金supported by the National Natural Science Foun-dation of China(Grant No.52206165)Key R&D Projects in Sichuan Province(Grant No.2022YFG0219)。
文摘Transient electronics is a versatile tool that finds applications in various fields,including medical biology,environmental protection,and data information security.In the context of data protection,the traditional passive degradation transient mode is being replaced by the active destruction mode,which features a short self-destruction time and provides greater resistance to recovery.This article presents an overview of recent progress in transient electronics,assessing the benefits and suitability of varying transient mechanisms.The article also analyses the influence of transient electronics on military security while emphasizing the advantages of implementing energetic materials.Besides,the article introduces energetic transient devices and evaluates their ability to support the autonomous operation of transient electronic devices.
基金supported financially by the Excellent Going Abroad Expert's Training Program in Hebei Province (No. 201940)the Hebei Natural Science Foundation of China (No. H2020208030)the S & T Program of Hebei (No. 22567607H) for financial support。
文摘A nickel-catalyzed C(sp^(2))–H alkynylation of unprotected α-substituted benzylamines is achieved by utilizing a transient directing group. The combination of a TDG with a nickel catalyst significantly improves the reaction step and atom economy. It has been investigated that the 2,4,6-trimethylpyridine ligand was critical to achieve the optimized reactivity. This protocol provides a straightforward route for synthesizing the alkynylated free benzylamines, featuring good substrate compatibility and monoselectivity.
基金This work was supported by the National Natural Science Foundation of China(Grants Nos.12222214,12132020,12002400,and 12172386)by Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices(Grant No.2022B1212010008)+1 种基金by the National Natural Science Foundation of Guangdong Province(Grant No.2021B1515020021)by the Shenzhen Science and Techonlogy Program(Grant Nos.202206193000001 and 20220818181805001).
文摘Transient negative capacitance(NC),as an available dynamic charge effect achieved in resistor-ferroelectric capacitor(R-FEC)circuits,has triggered a series of theoretical and experimental works focusing on its physical mechanism and device application.Here,we analytically derived the effects of different mechanical conditions on the transient NC behaviors in the R-FEC circuit based on the phenomenological model.It shows that the ferroelectric capacitor can exhibit either NC(i.e.,“single NC”and“double NC”)or positive capacitance,depending on the mechanical condition and temperature.Further numerical calculations show that the voltage drop caused by NC can be effectively controlled by temperature,applied stress,or strain.The relationship between NC voltage drop and system configurations including external resistance,dynamical coefficient of polarization,and input voltage are presented,showing diverse strategies to manipulate the NC effect.These results provide theoretical guidelines for rational design and efficient control of NC-related electronic devices.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDC0160000)the National Natural Science Foundation of China(No.52122603)+4 种基金the Excellence Research Group Program(No.52488101)the Shandong Provincial Natural Science Foundation of China(No.ZR2024JQ011)the Project of National Key Laboratory of Science and Technology on Advanced Light-duty Gas-turbine(No.2023-JJ-Y04)the National Science and Technology Major Project of China(No.J2019-III-0003-0046)the Taishan Scholars Program of China.
文摘A pre-swirl system with a multi-chamber structure is crucial to the secondary air system of an aero engine.The airflow within the pre-swirl system(characterized by high-speed rotation and compressible flow)is complicated.During transient processes in aero engine operation,the pre-swirl system is subjected to upstream fluctuations,which is a less studied aspect.This paper delves into the unsteady flow characteristics within the pre-swirl system.We investigate the influence of different pressure-fluctuation boundary conditions,corresponding to step function,ramp function,and sine function,on the transient response characteristics of the pre-swirl system.The results indicate that the response characteristics are strongly affected by the upstream boundary conditions.An obvious overshoot phenomenon is observed in the actual temperature drop under the step and ramp function conditions.The peak time of the step function is 75%shorter compared to the ramp function.Furthermore,the flow parameters exhibit nonlinear growth during the transient process,emphasizing the need for consideration in future quasi-steady simulations.For the sine function condition,the pressure-fluctuation frequency minimally affects stable values of mass flow rate and actual temperature drop but exerts a substantial influence on the maximum deviation of actual temperature drop of the system.As the frequency increases from 100 Hz to 200 Hz,the maximum deviations for actual temperature drop change from around±13 K to±10 K.
