Regenerative medicine by cell transplantation is a novel therapy for treating end-stage organ failure and tissue damage. Cell-based therapy based on the transplantation of neural stem/progenitor cells （NSPCs） repres...Regenerative medicine by cell transplantation is a novel therapy for treating end-stage organ failure and tissue damage. Cell-based therapy based on the transplantation of neural stem/progenitor cells （NSPCs） represents an attractive strategy for the treatment of neurodegenerative diseases, but obtaining large numbers of these cells is difficult and their differentiation potential is strictly restricted in a spatiotemporally-regulated manner during central nervous system （CNS） development. Therefore, embryonic stem cells and induced pluripotent stem cells represent an attractive alternative for cell-transplantation therapy in regenerative medicine.展开更多
Green and low cost CO_(2) and CaO were used to stimulate amine emulsions to reveal the responsive behavior of amine emulsions.On this basis,oil-based drilling fluids responsive to CO_(2) and CaO were formulated and th...Green and low cost CO_(2) and CaO were used to stimulate amine emulsions to reveal the responsive behavior of amine emulsions.On this basis,oil-based drilling fluids responsive to CO_(2) and CaO were formulated and their properties were evaluated.The results showed that the amine emulsions inversed from water-in-oil state to oil-in-water state readily and their rheological behavior underwent transitions of decreasing,rising again and decreasing again via induction by CO_(2).These CO_(2) responsive behaviors could be reversed by CaO.Oil-based drilling fluids prepared based on the amine emulsions with oil-water volume ratios of 50:50 to 70:30,densities of 1.4-2.0 g/cm^(3) had good rheological and filtration properties at 160℃;and be readily cleaned up using CO_(2) bubbling.The useless solid phase with low density could be removed efficiently via reducing the viscosity of emulsion by CO_(2) and the residual liquid phase could be restored to the original state by CaO and reused to prepare drilling fluid.The mechanisms analysis indicated that CO_(2)/CaO induced the reversible conversion between amine emulsifiers and their salts,which enabled the reversible regulation of both the hydrophilic-lipophilic balance of amine emulsifiers and the emulsion particles’size and finally caused the controllable-reversion of the form and rheology of amine emulsion.展开更多
A large quantity of unmanned aerial vehicle(UAV)trajectory data related to air traffic information has important value in engineering fields.However,the cost of data and trajectory processing limits the applications,a...A large quantity of unmanned aerial vehicle(UAV)trajectory data related to air traffic information has important value in engineering fields.However,the cost of data and trajectory processing limits the applications,and as the number of UAVs increases rapidly,future UAVs'path data will be very large.Therefore,this paper designs a multi-UAV route re-generation method based on trajectory data,which can realize the UAVs'path data compression,de-aggregation,and regeneration tasks.Based on the trajectory data,the three-dimensional Douglas-Peucker algorithm is used to compress the trajectory data to reduce the storage space.The improved B-spline path smoothing algorithm based on the reversing control point is used to depolymerize and smooth the path.Simulation experiments show that the above multi-UAV route re-generation algorithm can obtain a more optimized path while maintaining the important characteristics of the original path.展开更多
Hybrid AC/DC distribution networks are promising candidates for future applications due to their rapid advancement in power electronics technology.They use interface converters(IFCs)to link DC and AC distribution netw...Hybrid AC/DC distribution networks are promising candidates for future applications due to their rapid advancement in power electronics technology.They use interface converters(IFCs)to link DC and AC distribution networks.However,the networks possess drawbacks with AC voltage and frequency offsets when transferring from grid-tied to islanding modes.To address these problems,this paper proposes a simple but effective strategy based on the reverse droop method.Initially,the power balance equation of the distribution system is derived,which reveals that the cause of voltage and frequency offsets is the mismatch between the IFC output power and the rated load power.Then,the reverse droop control is introduced into the IFC controller.By using a voltage-active power/frequency-reactive power(U-P/f-Q)reverse droop loop,the IFC output power enables adaptive tracking of the rated load power.Therefore,the AC voltage offset and frequency offset are suppressed during the transfer process of operational modes.In addition,the universal parameter design method is discussed based on the stability limitations of the control system and the voltage quality requirements of AC critical loads.Finally,simulation and experimental results clearly validate the proposed control strategy and parameter design method.展开更多
To effectively solve the problems of inconsistent communication protocols in automatic monitoring equipment,and limited data acquisition transmission and monitoring equipment,this paper developed programmable single p...To effectively solve the problems of inconsistent communication protocols in automatic monitoring equipment,and limited data acquisition transmission and monitoring equipment,this paper developed programmable single point multiple output intelligent data acquisition and transmission system. It made an in-depth elaboration of the data acquisition and transmission system from hardware design,software architecture and principle,main functions and technical parameters. Finally,it came up with four innovation points:(i) intelligent(automatic)matching a variety of communication protocols for environmental monitoring equipment,(ii) realizing multi-protocol and multi-target parallel data transmission,(iii) realizing remote dynamic input of control instructions through wired or wireless network,and(iv) supporting configuration(process) simulation of field equipment DCS operating conditions.展开更多
RNA plays a pivotal role in genetic information transmission,gene expression regulation,and key biological processes,making its functional regulation critical.In this study,we introduce an iedDA-based strategy for pos...RNA plays a pivotal role in genetic information transmission,gene expression regulation,and key biological processes,making its functional regulation critical.In this study,we introduce an iedDA-based strategy for post-synthetic RNA modification,enabling controlled nucleic acid cleavage via the CRISPR-Cas system.By modifying RNA with trans-cyclooctene(TCO),its function is paused,and reactivation is achieved using the repair agent dimethyl-tetrazine(Me2Tz),triggering the iedDA reaction.We demonstrate reversible on/off switching of CRISPR-Cas activity in vitro and further validate the strategy's applicability to other RNA systems,highlighting its potential for gene editing in cells.展开更多
The control system of a catalytic flow reversal reactor （CFRR） for the mitigation of ventilation air methane was investigated. A one-dimensional heteroge- neous model with a logic-based controller was applied to sim...The control system of a catalytic flow reversal reactor （CFRR） for the mitigation of ventilation air methane was investigated. A one-dimensional heteroge- neous model with a logic-based controller was applied to simulate the CFRR. The simulation results indicated that the controller developed in this work performs well under normal conditions. Air dilution and auxiliary methane injection are effective to avoid the catalyst overheating and reaction extinction caused by prolonged rich and lean feed conditions, respectively. In contrast, the reactor is prone to lose control by adjusting the switching time solely. Air dilution exhibits the effects of two contradictory aspects on the operation of CFRR, i.e., cooling the bed and accumulating heat, though the former is in general more prominent. Lowering the reference temperature for flow reversal can decrease the bed temperature and benefit stable operation under rich methane feed condition.展开更多
In this study,we prepared a polar flexible single crystal of[Zn(4-ethylpyridine)_(2)(NCS)_(2)].This material shows unusually large anisotropic linear thermal expansion as the tetrahedral coordination geometry of the c...In this study,we prepared a polar flexible single crystal of[Zn(4-ethylpyridine)_(2)(NCS)_(2)].This material shows unusually large anisotropic linear thermal expansion as the tetrahedral coordination geometry of the complex can be modified in response to the thermal dynamic state of the ethyl group in 4-ethylpyridine ligands.Correspondingly,a giant thermally controlled reversible shape change of 10%elongation/contraction is observed in the rod-like single crystal along its long axis.Such a large thermal mechanical deformation is among the largest values in the reported thermal dynamic single crystals.Because the magnitude of dipole moment of uniaxially aligned molecules is varied by the large molecular structural change,the polarization of the single crystal is switched and manifests as a continuous pyroelectric current,particularly in the vicinity of phase transition points where molecular geometries are largely tuned.This study demonstrates that the large thermal expansion of flexible single crystals can be used to control the polarization of materials,providing a promising strategy to prepare superior pyroelectric materials.展开更多
文摘Regenerative medicine by cell transplantation is a novel therapy for treating end-stage organ failure and tissue damage. Cell-based therapy based on the transplantation of neural stem/progenitor cells （NSPCs） represents an attractive strategy for the treatment of neurodegenerative diseases, but obtaining large numbers of these cells is difficult and their differentiation potential is strictly restricted in a spatiotemporally-regulated manner during central nervous system （CNS） development. Therefore, embryonic stem cells and induced pluripotent stem cells represent an attractive alternative for cell-transplantation therapy in regenerative medicine.
基金Suppported by National Natural Science Foundation of China(NO.51804263)Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance(NO.2020CX040102,NO.2020CX040201)。
文摘Green and low cost CO_(2) and CaO were used to stimulate amine emulsions to reveal the responsive behavior of amine emulsions.On this basis,oil-based drilling fluids responsive to CO_(2) and CaO were formulated and their properties were evaluated.The results showed that the amine emulsions inversed from water-in-oil state to oil-in-water state readily and their rheological behavior underwent transitions of decreasing,rising again and decreasing again via induction by CO_(2).These CO_(2) responsive behaviors could be reversed by CaO.Oil-based drilling fluids prepared based on the amine emulsions with oil-water volume ratios of 50:50 to 70:30,densities of 1.4-2.0 g/cm^(3) had good rheological and filtration properties at 160℃;and be readily cleaned up using CO_(2) bubbling.The useless solid phase with low density could be removed efficiently via reducing the viscosity of emulsion by CO_(2) and the residual liquid phase could be restored to the original state by CaO and reused to prepare drilling fluid.The mechanisms analysis indicated that CO_(2)/CaO induced the reversible conversion between amine emulsifiers and their salts,which enabled the reversible regulation of both the hydrophilic-lipophilic balance of amine emulsifiers and the emulsion particles’size and finally caused the controllable-reversion of the form and rheology of amine emulsion.
文摘A large quantity of unmanned aerial vehicle(UAV)trajectory data related to air traffic information has important value in engineering fields.However,the cost of data and trajectory processing limits the applications,and as the number of UAVs increases rapidly,future UAVs'path data will be very large.Therefore,this paper designs a multi-UAV route re-generation method based on trajectory data,which can realize the UAVs'path data compression,de-aggregation,and regeneration tasks.Based on the trajectory data,the three-dimensional Douglas-Peucker algorithm is used to compress the trajectory data to reduce the storage space.The improved B-spline path smoothing algorithm based on the reversing control point is used to depolymerize and smooth the path.Simulation experiments show that the above multi-UAV route re-generation algorithm can obtain a more optimized path while maintaining the important characteristics of the original path.
基金This work was supported by the National Key R&D Program of China(2018YFB0904700).
文摘Hybrid AC/DC distribution networks are promising candidates for future applications due to their rapid advancement in power electronics technology.They use interface converters(IFCs)to link DC and AC distribution networks.However,the networks possess drawbacks with AC voltage and frequency offsets when transferring from grid-tied to islanding modes.To address these problems,this paper proposes a simple but effective strategy based on the reverse droop method.Initially,the power balance equation of the distribution system is derived,which reveals that the cause of voltage and frequency offsets is the mismatch between the IFC output power and the rated load power.Then,the reverse droop control is introduced into the IFC controller.By using a voltage-active power/frequency-reactive power(U-P/f-Q)reverse droop loop,the IFC output power enables adaptive tracking of the rated load power.Therefore,the AC voltage offset and frequency offset are suppressed during the transfer process of operational modes.In addition,the universal parameter design method is discussed based on the stability limitations of the control system and the voltage quality requirements of AC critical loads.Finally,simulation and experimental results clearly validate the proposed control strategy and parameter design method.
文摘To effectively solve the problems of inconsistent communication protocols in automatic monitoring equipment,and limited data acquisition transmission and monitoring equipment,this paper developed programmable single point multiple output intelligent data acquisition and transmission system. It made an in-depth elaboration of the data acquisition and transmission system from hardware design,software architecture and principle,main functions and technical parameters. Finally,it came up with four innovation points:(i) intelligent(automatic)matching a variety of communication protocols for environmental monitoring equipment,(ii) realizing multi-protocol and multi-target parallel data transmission,(iii) realizing remote dynamic input of control instructions through wired or wireless network,and(iv) supporting configuration(process) simulation of field equipment DCS operating conditions.
基金National Natural Science Foundation of China(Nos.22177089,21721005,92153303,22037004,22177088)the Fundamental Research Funds for the Central Universities(2042021kf0211).
文摘RNA plays a pivotal role in genetic information transmission,gene expression regulation,and key biological processes,making its functional regulation critical.In this study,we introduce an iedDA-based strategy for post-synthetic RNA modification,enabling controlled nucleic acid cleavage via the CRISPR-Cas system.By modifying RNA with trans-cyclooctene(TCO),its function is paused,and reactivation is achieved using the repair agent dimethyl-tetrazine(Me2Tz),triggering the iedDA reaction.We demonstrate reversible on/off switching of CRISPR-Cas activity in vitro and further validate the strategy's applicability to other RNA systems,highlighting its potential for gene editing in cells.
文摘The control system of a catalytic flow reversal reactor （CFRR） for the mitigation of ventilation air methane was investigated. A one-dimensional heteroge- neous model with a logic-based controller was applied to simulate the CFRR. The simulation results indicated that the controller developed in this work performs well under normal conditions. Air dilution and auxiliary methane injection are effective to avoid the catalyst overheating and reaction extinction caused by prolonged rich and lean feed conditions, respectively. In contrast, the reactor is prone to lose control by adjusting the switching time solely. Air dilution exhibits the effects of two contradictory aspects on the operation of CFRR, i.e., cooling the bed and accumulating heat, though the former is in general more prominent. Lowering the reference temperature for flow reversal can decrease the bed temperature and benefit stable operation under rich methane feed condition.
基金supported by the National Natural Science Foundation of China(22071009,92061106,and 21971016)Beijing Institute of Technology Research Fund Program for Young Scholarssupport from the staff at the Analysis&Testing Center,Beijing Institute of Technology is also appreciated.
文摘In this study,we prepared a polar flexible single crystal of[Zn(4-ethylpyridine)_(2)(NCS)_(2)].This material shows unusually large anisotropic linear thermal expansion as the tetrahedral coordination geometry of the complex can be modified in response to the thermal dynamic state of the ethyl group in 4-ethylpyridine ligands.Correspondingly,a giant thermally controlled reversible shape change of 10%elongation/contraction is observed in the rod-like single crystal along its long axis.Such a large thermal mechanical deformation is among the largest values in the reported thermal dynamic single crystals.Because the magnitude of dipole moment of uniaxially aligned molecules is varied by the large molecular structural change,the polarization of the single crystal is switched and manifests as a continuous pyroelectric current,particularly in the vicinity of phase transition points where molecular geometries are largely tuned.This study demonstrates that the large thermal expansion of flexible single crystals can be used to control the polarization of materials,providing a promising strategy to prepare superior pyroelectric materials.
