The application of three-dimensional printed polymer scaffolds in repairing bone defects is a promising strategy.Among them,polycaprolactone(PCL)scaffolds are widely studied due to their good processability and contro...The application of three-dimensional printed polymer scaffolds in repairing bone defects is a promising strategy.Among them,polycaprolactone(PCL)scaffolds are widely studied due to their good processability and controlled degradation rate.However,as an alternative graft for repairing bone defects,PCL materials have poor hydrophilicity,which is not conducive to cell adhesion and growth.In addition,the poor mechanical properties of PCL materials cannot meet the strength required to repair bone defects.In this paper,nano-zirconium dioxide(ZrO2)powder is embedded in PCL material through a meltmixing process,and a regular grid scaffold is constructed by 3D printing.The embedding of nanometer zirconium dioxide powder improves the hydrophilicity and water absorption of the composite scaffold,which is conducive to cell adhesion,proliferation and growth and is beneficial to the exchange of nutrients.Therefore,the PCL/ZrO2 composite scaffold showed better biological activity in vitro.At the same time,the PCL/ZrO2 composite material system significantly improves the mechanical properties of the scaffold.Among them,compared with the pure PCL scaffold,the Young’s modulus is increased by about 0.4 times,and the compressive strength is increased by about 0.5 times.In addition,the osteogenic differentiation results also showed that the PCL/ZrO2 composite scaffold group showed better ALP activity and more effective bone mineralization than the pure PCL group.We believe that the 3D printed PCL/ZrO2 composite scaffold has certain application prospects in repairing bone defects.展开更多
Flexible electrodes have demonstrated better biocompatibility than rigid electrodes in relieving tissue encapsulation and long-term recording.Nonhuman primates are closer to humans in their brains’structural and func...Flexible electrodes have demonstrated better biocompatibility than rigid electrodes in relieving tissue encapsulation and long-term recording.Nonhuman primates are closer to humans in their brains’structural and functional properties,thus making them more suitable than rodents as animal models for potential clinical usage.However,the application of flexible electrodes on nonhuman primates has rarely been reported.In the present study,a flexible multichannel electrode array for nonhuman primates was developed and implemented for extracellular recording in behaving monkeys.To minimize the window of durotomy for reducing possible risks,a guide-tube-compatible implantation solution was designed to deliver the flexible electrodes through the dura into the cortex.The proposed structure for inserting flexible electrodes was characterized ex vivo and validated in vivo.Furthermore,acute recording of multichannel flexible electrodes for the primates was performed.The results showed that the flexible electrodes and implantation method used in this study meet the needs of extracellular recording in nonhuman primates.Task-related neuronal activities with a high signal-to-noise ratio of spikes demonstrated that our whole device is currently a minimally invasive and clinically viable approach for extracellular recording.展开更多
The fluctuation law of magnetic fluid seal interface of an agricultural centrifugal pump is theoretically unknown;the pressure and velocity fluctuations are crucial factors that cause interface fluctuation.In this stu...The fluctuation law of magnetic fluid seal interface of an agricultural centrifugal pump is theoretically unknown;the pressure and velocity fluctuations are crucial factors that cause interface fluctuation.In this study,the pressure and velocity fluctuations of the sealing interface on an agricultural centrifugal pump during cavitation were investigated based on the methods of Ansys CFX numerical calculation and experimental verification.The results demonstrated that at the same flow rate,the pressure fluctuation amplitude of the sealing interface decreased gradually from the shaft surface to the bottom of the polar tooth.At different flow rates,the amplitude of the pressure fluctuation decreased with an increase in the flow rate.The cavitation of the medium aggravated the impact and water hammer of the liquid,leading to the occurrence of the jitter phenomenon in the sealing interface to accelerate the fluctuation frequency of the axial velocity of the sealing liquid,which accelerated the emulsification of the magnetic fluid.This law can provide a reference for the design of magnetic fluid sealing devices for agricultural centrifugal pumps.展开更多
The latest advance in recommendation shows that better user and item representations can be learned via performing graph convolutions on the user-item interaction graph.However,such finding is mostly restricted to the...The latest advance in recommendation shows that better user and item representations can be learned via performing graph convolutions on the user-item interaction graph.However,such finding is mostly restricted to the collaborative filtering(CF)scenario,where the interaction contexts are not available.In this work,we extend the advantages of graph convolutions to context-aware recommender system(CARS,which represents a generic type of models that can handle various side information).We propose Graph Convolution Machine(GCM),an end-to-end framework that consists of three components:an encoder,graph convolution(GC)layers,and a decoder.The encoder projects users,items,and contexts into embedding vectors,which are passed to the GC layers that refine user and item embeddings with context-aware graph convolutions on the user-item graph.The decoder digests the refined embeddings to output the prediction score by considering the interactions among user,item,and context embeddings.We conduct experiments on three real-world datasets from Yelp and Amazon,validating the effectiveness of GCM and the benefits of performing graph convolutions for CARS.展开更多
Heat shock response is a classical stress-induced regulatory system in bacteria, character- ized by extensive transcriptional reprogramming. To compare the impact of heat stress on the tran- scriptome and translatome ...Heat shock response is a classical stress-induced regulatory system in bacteria, character- ized by extensive transcriptional reprogramming. To compare the impact of heat stress on the tran- scriptome and translatome in Escherich& coli, we conducted ribosome profiling in parallel with RNA-Seq to investigate the alterations in transcription and translation efficiency when E. coli cells were exposed to a mild heat stress (from 30 ~C to 45 ~C). While general changes in ribosome foot- prints correlate with the changes of mRNA transcripts upon heat stress, a number of genes show differential changes at the transcription and translation levels. Translation efficiency of a few genes that are related to environment stimulus response is up-regulated, and in contrast, some genes func- tioning in mRNA translation and amino acid biosynthesis are down-regulated at the translation level in response to heat stress. Moreover, our ribosome occupancy data suggest that in generalribosomes accumulate remarkably in the starting regions of ORFs upon heat stress. This study pro- vides additional insights into bacterial gene expression in response to heat stress, and suggests the presence of stress-induced but yet-to-be characterized cellular regulatory mechanisms of gene expression at translation level.展开更多
文摘The application of three-dimensional printed polymer scaffolds in repairing bone defects is a promising strategy.Among them,polycaprolactone(PCL)scaffolds are widely studied due to their good processability and controlled degradation rate.However,as an alternative graft for repairing bone defects,PCL materials have poor hydrophilicity,which is not conducive to cell adhesion and growth.In addition,the poor mechanical properties of PCL materials cannot meet the strength required to repair bone defects.In this paper,nano-zirconium dioxide(ZrO2)powder is embedded in PCL material through a meltmixing process,and a regular grid scaffold is constructed by 3D printing.The embedding of nanometer zirconium dioxide powder improves the hydrophilicity and water absorption of the composite scaffold,which is conducive to cell adhesion,proliferation and growth and is beneficial to the exchange of nutrients.Therefore,the PCL/ZrO2 composite scaffold showed better biological activity in vitro.At the same time,the PCL/ZrO2 composite material system significantly improves the mechanical properties of the scaffold.Among them,compared with the pure PCL scaffold,the Young’s modulus is increased by about 0.4 times,and the compressive strength is increased by about 0.5 times.In addition,the osteogenic differentiation results also showed that the PCL/ZrO2 composite scaffold group showed better ALP activity and more effective bone mineralization than the pure PCL group.We believe that the 3D printed PCL/ZrO2 composite scaffold has certain application prospects in repairing bone defects.
基金The project was supported by the National Key R&D Program of China(2020YFB1313402,2017YFA0701102,and 2017YFA0701104)the Shanghai Municipal Science and Technology Major Project(2021SHZDZX)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences Pilot Project(XDB32030102,XDB32040203,and XDA16021305)and the National Natural Science Foundation of China(62071447).
文摘Flexible electrodes have demonstrated better biocompatibility than rigid electrodes in relieving tissue encapsulation and long-term recording.Nonhuman primates are closer to humans in their brains’structural and functional properties,thus making them more suitable than rodents as animal models for potential clinical usage.However,the application of flexible electrodes on nonhuman primates has rarely been reported.In the present study,a flexible multichannel electrode array for nonhuman primates was developed and implemented for extracellular recording in behaving monkeys.To minimize the window of durotomy for reducing possible risks,a guide-tube-compatible implantation solution was designed to deliver the flexible electrodes through the dura into the cortex.The proposed structure for inserting flexible electrodes was characterized ex vivo and validated in vivo.Furthermore,acute recording of multichannel flexible electrodes for the primates was performed.The results showed that the flexible electrodes and implantation method used in this study meet the needs of extracellular recording in nonhuman primates.Task-related neuronal activities with a high signal-to-noise ratio of spikes demonstrated that our whole device is currently a minimally invasive and clinically viable approach for extracellular recording.
基金support of the National Natural Science Foundation of China(Grant No.52079118)the Science and Technology Department of Sichuan Province(Grant No.2020YFH0135)+2 种基金the Open Research Subject of Key Laboratory of Fluid and Power Machinery(Xihua University)Ministry of Education(Grant No.LTDL2021-005)Project of Science and Technology Department of Sichuan Province,(Grant No.202573).
文摘The fluctuation law of magnetic fluid seal interface of an agricultural centrifugal pump is theoretically unknown;the pressure and velocity fluctuations are crucial factors that cause interface fluctuation.In this study,the pressure and velocity fluctuations of the sealing interface on an agricultural centrifugal pump during cavitation were investigated based on the methods of Ansys CFX numerical calculation and experimental verification.The results demonstrated that at the same flow rate,the pressure fluctuation amplitude of the sealing interface decreased gradually from the shaft surface to the bottom of the polar tooth.At different flow rates,the amplitude of the pressure fluctuation decreased with an increase in the flow rate.The cavitation of the medium aggravated the impact and water hammer of the liquid,leading to the occurrence of the jitter phenomenon in the sealing interface to accelerate the fluctuation frequency of the axial velocity of the sealing liquid,which accelerated the emulsification of the magnetic fluid.This law can provide a reference for the design of magnetic fluid sealing devices for agricultural centrifugal pumps.
基金supported by the National Key Research and Development Program of China (2020AAA0106000)the National Natural Science Foundation of China (Grant Nos.61972372,U19A2079,62121002).
文摘The latest advance in recommendation shows that better user and item representations can be learned via performing graph convolutions on the user-item interaction graph.However,such finding is mostly restricted to the collaborative filtering(CF)scenario,where the interaction contexts are not available.In this work,we extend the advantages of graph convolutions to context-aware recommender system(CARS,which represents a generic type of models that can handle various side information).We propose Graph Convolution Machine(GCM),an end-to-end framework that consists of three components:an encoder,graph convolution(GC)layers,and a decoder.The encoder projects users,items,and contexts into embedding vectors,which are passed to the GC layers that refine user and item embeddings with context-aware graph convolutions on the user-item graph.The decoder digests the refined embeddings to output the prediction score by considering the interactions among user,item,and context embeddings.We conduct experiments on three real-world datasets from Yelp and Amazon,validating the effectiveness of GCM and the benefits of performing graph convolutions for CARS.
基金supported by the National Natural Science Foundation of China(Grant Nos.31630087,31422016,and 31470722 to NGGrant Nos.31671381 and 91540109 to XY)
文摘Heat shock response is a classical stress-induced regulatory system in bacteria, character- ized by extensive transcriptional reprogramming. To compare the impact of heat stress on the tran- scriptome and translatome in Escherich& coli, we conducted ribosome profiling in parallel with RNA-Seq to investigate the alterations in transcription and translation efficiency when E. coli cells were exposed to a mild heat stress (from 30 ~C to 45 ~C). While general changes in ribosome foot- prints correlate with the changes of mRNA transcripts upon heat stress, a number of genes show differential changes at the transcription and translation levels. Translation efficiency of a few genes that are related to environment stimulus response is up-regulated, and in contrast, some genes func- tioning in mRNA translation and amino acid biosynthesis are down-regulated at the translation level in response to heat stress. Moreover, our ribosome occupancy data suggest that in generalribosomes accumulate remarkably in the starting regions of ORFs upon heat stress. This study pro- vides additional insights into bacterial gene expression in response to heat stress, and suggests the presence of stress-induced but yet-to-be characterized cellular regulatory mechanisms of gene expression at translation level.