Difunctionalization of unsaturated hydrocarbons is a pivotal synthetic strategy enabling the conversion of alkenes and alkynes into high value-added compounds.It allows for the introduction of two functional groups in...Difunctionalization of unsaturated hydrocarbons is a pivotal synthetic strategy enabling the conversion of alkenes and alkynes into high value-added compounds.It allows for the introduction of two functional groups into the unsaturated bond in a single step,facilitating the efficient construction of complex molecular architectures,which has been widely utilized in material chemistry,pharmaceutical and fine chemical synthesis.Recently,significant progress has been made via free radical-mediated difunctionalization due to the extensive application of photocatalysis.However,highly selective difunc-tionalization reactions still remain challenging.The research progress of selective difunctionalization of unsaturated hydro-carbons using a free radical addition/functional group migration strategy over the past decade is summarized,and synthetic strategies and key reaction steps are systematically elaborated.展开更多
Atrazine causes concern due to its resistant to biodegradation and could be accumulated in aquatic organisms,causing pollution in lakes.This study measured the concentration of atrazine in ice and the water under ice ...Atrazine causes concern due to its resistant to biodegradation and could be accumulated in aquatic organisms,causing pollution in lakes.This study measured the concentration of atrazine in ice and the water under ice through a simulated icing experiment and calculated the distribution coefficient K to characterize its migration ability in the freezing process.Furthermore,density functional theory(DFT)calculations were employed to expatiate the migration law of atrazine during icing process.According to the results,it could release more energy into the environment when atrazine staying in water phase(-15.077 kcal/mol)than staying in ice phase(-14.388 kcal/mol),therefore it was beneficial for the migration of atrazine from ice to water.This explains that during the freezing process,the concentration of atrazine in the ice was lower than that in the water.Thermodynamic calculations indicated thatwhen the temperature decreases from268 to 248 K,the internal energy contribution of the compound of atrazine and ice molecule(water cluster)decreases at the same vibrational frequency,resulting in an increase in the free energy difference of the compound from-167.946 to-165.390 kcal/mol.This demonstrated the diminished migratory capacity of atrazine.This study revealed the environmental behavior of atrazine during lake freezing,which was beneficial for the management of atrazine and other pollutants during freezing and environmental protection.展开更多
With the advancements of software defined network(SDN)and network function virtualization(NFV),service function chain(SFC)placement becomes a crucial enabler for flexible resource scheduling in low earth orbit(LEO)sat...With the advancements of software defined network(SDN)and network function virtualization(NFV),service function chain(SFC)placement becomes a crucial enabler for flexible resource scheduling in low earth orbit(LEO)satellite networks.While due to the scarcity of bandwidth resources and dynamic topology of LEO satellites,the static SFC placement schemes may cause performance degradation,resource waste and even service failure.In this paper,we consider migration and establish an online migration model,especially considering the dynamic topology.Given the scarcity of bandwidth resources,the model aims to maximize the total number of accepted SFCs while incurring as little bandwidth cost of SFC transmission and migration as possible.Due to its NP-hardness,we propose a heuristic minimized dynamic SFC migration(MDSM)algorithm that only triggers the migration procedure when new SFCs are rejected.Simulation results demonstrate that MDSM achieves a performance close to the upper bound with lower complexity.展开更多
Schwann cell transplantation is considered one of the most promising cell-based therapy to repair injured spinal cord due to its unique growth-promoting and myelin-forming properties.A the Food and Drug Administration...Schwann cell transplantation is considered one of the most promising cell-based therapy to repair injured spinal cord due to its unique growth-promoting and myelin-forming properties.A the Food and Drug Administration-approved Phase I clinical trial has been conducted to evaluate the safety of transplanted human autologous Schwann cells to treat patients with spinal cord injury.A major challenge for Schwann cell transplantation is that grafted Schwann cells are confined within the lesion cavity,and they do not migrate into the host environment due to the inhibitory barrier formed by injury-induced glial scar,thus limiting axonal reentry into the host spinal cord.Here we introduce a combinatorial strategy by suppressing the inhibitory extracellular environment with injection of lentivirus-mediated transfection of chondroitinase ABC gene at the rostral and caudal borders of the lesion site and simultaneously leveraging the repair capacity of transplanted Schwann cells in adult rats following a mid-thoracic contusive spinal cord injury.We report that when the glial scar was degraded by chondroitinase ABC at the rostral and caudal lesion borders,Schwann cells migrated for considerable distances in both rostral and caudal directions.Such Schwann cell migration led to enhanced axonal regrowth,including the serotonergic and dopaminergic axons originating from supraspinal regions,and promoted recovery of locomotor and urinary bladder functions.Importantly,the Schwann cell survival and axonal regrowth persisted up to 6 months after the injury,even when treatment was delayed for 3 months to mimic chronic spinal cord injury.These findings collectively show promising evidence for a combinatorial strategy with chondroitinase ABC and Schwann cells in promoting remodeling and recovery of function following spinal cord injury.展开更多
Lithium-rich manganese-based materials(LRMs) are promising cathode for high-energy-density lithiumion batteries due to their high capacity,low toxicity,and low cost.However,LRMs suffer from serious voltage decay and c...Lithium-rich manganese-based materials(LRMs) are promising cathode for high-energy-density lithiumion batteries due to their high capacity,low toxicity,and low cost.However,LRMs suffer from serious voltage decay and capacity fade due to continual migration and dissolution of transition metal ions(TMs) during cycling process.Herein,a novel strategy is proposed to inhibit the TMs migration of LRMs through a modified separator by means of functionalized carbon coating layer,which depends on the chemical constraint of the abundant functional groups in the modified super P.In addition,it has been found that the dissolution of TMs can be restrained based on the Le Chatelier's principle.Moreover,the modified separator owns good wettability toward the electrolyte.As a result,the LRMs cathode with the modified separator delivers a high discharge capacity of 329.93 mA h g-1 at 0.1 C,and achieves good cyclic performance,the enhanced reaction kinetics and low voltage decay.Therefore,this work provides a new idea to promote the comprehensive electrochemical performances of Li-ion batteries with LRMs cathode through a strategy of separator modification.展开更多
Plasticizers that are generally used in plastics to produce flexible food packaging materials have proved to cause reproductive system problems and women＇s infertility. A long- term consumption may even cause cancer ...Plasticizers that are generally used in plastics to produce flexible food packaging materials have proved to cause reproductive system problems and women＇s infertility. A long- term consumption may even cause cancer diseases. Hence a nano-scale layer, named as functional barrier layer, was deposited on the plastic surface to prevent plasticizer diethylhexyl phthalate＇s （DEHP） migration from plastics to foods. The feasibility of functional barrier layer i.e. SiOx coating through plasma enhanced chemical vapor deposition （PECVD） process was then described in this paper. We used Fourier transform infrared spectroscopy （FTIR） to analyze the chemical composition of coatings, scanning electron microscope （SEM） to explore the topography of the coating surfaces, surface profilemeter to measure thickness of coatings, and high-performance liquid chromatography （HPLC） to evaluate the barrier properties of coatings. The results have clearly shown that the coatings can perfectly block the migration of the DEHP from plastics to their containers. It is also concluded that process parameters significantly influence the block efficiency of the coatings. When the deposition conditions of SiOx coatings were optimized, i.e. 50 W of the discharge power, 4 ： 1 of ratio of O2 ： HMDSO, and ca.100 nm thickness of SiOx, 71.2% of the DEHP was effectively blocked.展开更多
Oxygen vacancy formation and migration in La0.9Sr0.1Ga0.8Mg0.2O3-5 （LSGM） with various crystal symmetries （cubic, rhombohedral, orthorhombic, and monoclinic） are studied by employing first-principles calculations ...Oxygen vacancy formation and migration in La0.9Sr0.1Ga0.8Mg0.2O3-5 （LSGM） with various crystal symmetries （cubic, rhombohedral, orthorhombic, and monoclinic） are studied by employing first-principles calculations based on density functional theory （DFT）. It is shown that the cubic LSGM has the smallest band gap, oxygen vacancy formation energy, and migration barrier, while the other three structures give rise to much larger values for these quantities, implying the best oxygen ion conductivity of the cubic LSGM among the four crystal structures. In out calculations, one oxygen vacancy migration pathway is considered in the cubic and rhombohedral structures due to all the oxygen sites being equivalent in them, while two vacancy migration pathways with different migration barriers are found in the orthorhombic and monoclinic symmetries owing to the existence of nonequivalent O1 and 02 oxygen sites. The migration energies along the migration pathway linking the two 02 sites are obviously lower than those along the pathway linking the O1 and 02 sites. Considering the phase transitions at high temperatures, the results obtained in this paper can not only explain the experimentally observed different behaviours of the oxygen ionic conductivity of LSGM with different symmetries, but also predict the rational crystal structures of LSGM for solid oxide fuel cell applications.展开更多
The presence of endogenous neural stem/progenitor cells in the adult mammalian brain suggests that the central nervous system can be repaired and regenerated after injury.However,whether it is possible to stimulate ne...The presence of endogenous neural stem/progenitor cells in the adult mammalian brain suggests that the central nervous system can be repaired and regenerated after injury.However,whether it is possible to stimulate neurogenesis and reconstruct cortical layers II to VI in non-neurogenic regions,such as the cortex,remains unknown.In this study,we implanted a hyaluronic acid collagen gel loaded with basic fibroblast growth factor into the motor cortex immediately following traumatic injury.Our findings reveal that this gel effectively stimulated the proliferation and migration of endogenous neural stem/progenitor cells,as well as their differentiation into mature and functionally integrated neurons.Importantly,these new neurons reconstructed the architecture of cortical layers II to VI,integrated into the existing neural circuitry,and ultimately led to improved brain function.These findings offer novel insight into potential clinical treatments for traumatic cerebral cortex injuries.展开更多
Elastic migration has been widely paid attention by employing the vector processing of mul- ticomponent seismic data. Ray based elastic Kirchhoff migration has such properties as high flexibility and high efficiency. ...Elastic migration has been widely paid attention by employing the vector processing of mul- ticomponent seismic data. Ray based elastic Kirchhoff migration has such properties as high flexibility and high efficiency. However, it has failed to solve many problems caused by multipath. On the other hand, elastic reverse-time migration （RTM） based on the two-way wave equation is known to be capable of dealing with these problems, but it is extremely expensive when applied in 3D cases and velocity model building. Based on the elastic Kirchhoff-Helmholtz integral, we calculate deeoupled backward-continued wavefields by introducing elastic Green functions for P- and S-waves, which is expressed by a summation of elastodynamic Gaussian beams. The PP and polarity-corrected PS images are obtained by calculating the correlation between downward and deeoupled backward-continued vector wavefields, where polarity correction is performed by analyzing the relation between the polarization direction of converted PS waves and incident angle on the interface. To a large extent, our method combines the high efficiency of ray-based migration with the high accuracy of wave-equation based reverse-time migration. Application of this method to multicomponent synthetic datasets from the fault model and Marmousi 2 model demonstrates the validity, flexibility and accuracy of the new method.展开更多
AIM:To hypothesize that beta-7 integrin affects cellularmigration of both,lymphocytes and enterocytes.METHODS:The nucleoside analog Brd U was ip injected in beta-7-deficient mice(C57BL/6-Itgbtmlcgn/J)of male gender an...AIM:To hypothesize that beta-7 integrin affects cellularmigration of both,lymphocytes and enterocytes.METHODS:The nucleoside analog Brd U was ip injected in beta-7-deficient mice(C57BL/6-Itgbtmlcgn/J)of male gender and age-matched male C57BL/J J mice(wild type)4,20,or 40 h before analysis.The total small intestine was isolated,dissected,and used for morphometrical studies.Brd U-positive epithelial cells were numbered in at least 15 hemi-crypts per duodenum,jejunum,and ileum of each animal.The outer most Brd U-positive cell(cellmax)was determined per hemi-crypt,numerically documented,and statistically analysed.RESULTS:Integrins containing the beta-7-chain were exclusively expressed on leukocytes.In the small intestinal mucosa of beta-7 integrin-deficient mice the number of intraepithelial lymphocytes was drastically decreased.Moreover,the Peyer’s patches of beta-7integrin-deficient mice appeared hypoplastic.In beta-7integrin-deficient mice the location of cellmax was found in a higher position than it was the case for the controls.The difference was already detected at 4 h after Brd U application,but significantly increased with time(40 h after Brd U injection)in all small intestinal segments investigated,i.e.,duodenum,jejunum,and ileum.Migration of small intestinal enterocytes was different between the experimental groups measured by cellmax locations.CONCLUSION:The E-cadherin beta-7 integrin pathway probably controls migration of enterocytes within the small intestinal surface lining epithelial layer.展开更多
MicroRNAs refer to a class of endogenous,short non-coding RNAs that mediate numerous biological functions.MicroRNAs regulate various physiological and pathological activities of peripheral nerves,including peripheral ...MicroRNAs refer to a class of endogenous,short non-coding RNAs that mediate numerous biological functions.MicroRNAs regulate various physiological and pathological activities of peripheral nerves,including peripheral nerve repair and regeneration.Previously,using a rat sciatic nerve injury model,we identified many functionally annotated novel microRNAs,including miR-sc14.Here,we used real-time reverse transcription-polymerase chain reaction to examine miR-sc14 expression in rat sciatic nerve stumps.Our results show that miRsc14 is noticeably altered following sciatic nerve injury,being up-regulated at 1 day and diminished at 7 days.EdU and transwell chamber assay results showed that miR-sc14 mimic promoted proliferation and migration of Schwann cells,while miR-sc14 inhiThe study was approved by the Jiangsu Provincial Laboratory Animal Management Committee,China on March 4,2015(approval No.20150304-004).bitor suppressed their proliferation and migration.Additionally,bioinformatic analysis examined potential target genes of miR-sc14,and found that fibroblast growth factor receptor 2 might be a potential target gene.Specifically,our results show changes of miR-sc14 expression in the sciatic nerve of rats at different time points after nerve injury.Appropriately,up-regulation of miR-sc14 promoted proliferation and migration of Schwann cells.Consequently,miR-sc14 may be an intervention target to promote repair of peripheral nerve injury.The study was approved by the Jiangsu Provincial Laboratory Animal Management Committee,China on March 4,2015(approval No.20150304-004).展开更多
AIM: To verify the hypothesis that caspase-8(Casp8), which regulates cellular apoptosis and necroptosis, is critically involved in enterocyte migration.METHODS: Casp8-silenced Caco2 cells were used in migration assays...AIM: To verify the hypothesis that caspase-8(Casp8), which regulates cellular apoptosis and necroptosis, is critically involved in enterocyte migration.METHODS: Casp8-silenced Caco2 cells were used in migration assays. In addition, enterocyte-specific Casp8 heterozygous(Casp8+/?int) or homozygous knockout mice(Casp8?int) were generated by crossing genetically modified mice carrying lox P recombination sites in intron 2 and 4 of the murine Casp8 gene with transgenic animals expressing a cre-transgene under control of the villin promoter in a pure C57/BL6 genetic background. The nucleoside analog Brd U was injected i.p. in male Casp8+/?int and Casp8?int animals 4 h, 20 h, or 40 h before performing morphometric studies. Locations of anti-Brd U-immunostained cells(cellmax) in at least 50 hemi-crypts of 6 histoanatomically distinct intestinal mucosal regions were numbered and extracted for statistical procedures. For the mice cohort(n = 28), the walking distance of enterocytes was evaluated from cellmax within crypt(n = 57), plateau(n = 19), and villus(n = 172) positions, resulting in a total of 6838 observations. Data analysis was performed by fitting a three-level mixed effects modelto the data.RESULTS: In cell culture experiments with Caco2 cells, Casp8 knockdown efficiency mediated by RNA interference on Casp8 transcripts was 80% controlled as determined by Western blotting. In the scratch assay, migration of Casp8-deleted Caco2 cells was significantly diminished when compared with controls(Casp8?scramble and Caco2). In Brd U-labeled Casp8?int mice, cellmax locations were found along the hemi-crypts in a lower position than it was for Casp8+/?int or control(cre-negative) animals. Statistical data analysis with a three-level mixed effects model revealed that in the six different intestinal locations(distinct segments of the small and large intestine), cell movement between the three mice groups differed widely. Especially in duodenal hemi-crypts, enterocyte movement was different between the groups. At 20 h, duodenal cellmax location was significantly lower in Casp8?int(25.67 ± 2.49) than in Casp8+/?int(35.67 ± 4.78; P < 0.05) or control littermates(44.33 ± 0.94; P < 0.01).CONCLUSION: C a s p 8- d e p e n d e n t m i g ra t i o n o f enterocytes is likely involved in intestinal physiology and inflammation-related pathophysiology.展开更多
BACKGROUND Stroke is a common cause of neurological dysfunction,often resulting in hemiplegia.Thus,rehabilitation of limb function in stroke patients is an important step towards accelerating recovery and improving qu...BACKGROUND Stroke is a common cause of neurological dysfunction,often resulting in hemiplegia.Thus,rehabilitation of limb function in stroke patients is an important step towards accelerating recovery and improving quality of life.AIM To investigate whether unilateral strength training in hemiplegic stroke patients could lead to cross-migration,an increase in bilateral muscle strength,and an improvement in lower limb motor function.METHODS We randomly divided 120 patients with hemiplegic stroke into two groups:Eexperimental and control groups,with 60 patients in each group.Both groups received routine rehabilitation treatment,while the experimental group additional-ly received ankle dorsiflexion resistance training on the healthy side for 6 wk.We measured the maximum voluntary contract(MVC),changes in surface electromyography(EMG),and the lower limb motor function using the simplified Fugl Meyer Motor Function Assessment Scale(FMA)before and within 1 wk after training.RESULTS The FMA score in the experimental group improved significantly compared to both their pre-training score and the control group's post-training score(P<0.05).The integrated EMG of the anterior tibialis muscle and pulmonary intestine muscle in the experimental group were significantly different after training than before(P<0.05).Furthermore,the MVC of the anterior tibialis muscle on both the healthy and affected sides and the MVC of the pulmonary intestine muscle on both sides showed significant improvement compared with before training and the control group(P<0.05).CONCLUSION Our findings suggest that ankle dorsiflexion resistance training on the healthy side in hemiplegic stroke patients can increase strength in the opposite tibialis anterior muscle and antagonist's muscle,indicating a cross-migration phenomenon of strength training.Furthermore,this type of training can also improve lower limb motor function,providing a new exercise method for improving early ankle dorsiflexion dysfunction.展开更多
Beamlet sources have strong local and directional character and can easily accomplish local illumination and migration. Besides, they provide better migration results than conventional migration methods. We introduce ...Beamlet sources have strong local and directional character and can easily accomplish local illumination and migration. Besides, they provide better migration results than conventional migration methods. We introduce the basic principles of beamlet prestack depth migration that includes a windowed Fourier transform and frame theory. We explain the Gabor-Daubechies （G-D） frame based on a Gaussian function. Beamlet decomposition provides information on the local space and direction of wavefield. We synthesize the beamlet source and beamlet records in the wavelet domain using both rectangle and Gaussian windows and then extrapolate the synthesized data with a Fourier finite-difference operator. We test the method using the standard Marmousi model. By comparing and analyzing the migration results of single directional beamlet and beamlets with different windows and directions, we demonstrate the validity of the prestack depth migration with Gaussian beamlets method.展开更多
Altitudinal bird migration involves seasonal shifts up and down the altitude gradient annually.Asia as the place with the largest number of altitudinal migrants,has quite few related studies,especially for montane and...Altitudinal bird migration involves seasonal shifts up and down the altitude gradient annually.Asia as the place with the largest number of altitudinal migrants,has quite few related studies,especially for montane and temperate avifaunas.To explore the potential drivers of seasonal altitudinal migration for birds in the middle of Hengduan Mountains,we conducted a three-year investigation on breeding and non-breeding season bird communities at eight elevational bands(1200–4200 m)in the Gongga Mountains.We examined the altitudinal migration patterns and relationships between seasonal distribution shifts and species'traits of 50 species with sufficient data recorded in both seasons.We found that a large proportion of breeding birds underwent altitudinal migration and showed three migration patterns(downslope shift,upslope shift,no shift).Seasonal distribution shifts were mainly correlated with certain ecological traits.Species breeding at high and mid-elevations,nesting in scrub and being omnivorous are more likely to show downslope movements during the non-breeding season.In addition,territorially weaker species exhibited more diverse migration patterns.Notably,we found the hand-wing index(HWI)was actually more convincing than body mass in explaining altitudinal migration.These results consolidate the studies of seasonal altitudinal migration in montane birds.Our study could be used to bridge existing knowledge gaps that currently impeding effective conservation for montane avifaunas in the Hengduan Mountains.展开更多
We sought to identify the differences between adolescents left behind in their home villages/towns(LBA)and non-left behind adolescents(NLB)on subjective well-being and family functioning due to parental migration in s...We sought to identify the differences between adolescents left behind in their home villages/towns(LBA)and non-left behind adolescents(NLB)on subjective well-being and family functioning due to parental migration in south China.We used a stratified cluster sampling method to recruit middle school students in a city experiencing population-emigration in Jiangxi Province in 2010.Participants included adolescents from families with:(1)one migrant parent,(2)both parents who migrated,or(3)non-left behind adolescents(i.e.,no migrant parent).To determine predictors of subjective well-being,we used structural equation models.Adolescents left behind by both parents(LBB)were less likely to express life satisfaction(P=0.038)in terms of their environments(P=0.011)compared with NLB.A parent or parents who migrated predicts lower subjective well-being of adolescents(P=0.051)and also lower academic performance.Being apart from their parents may affect family functioning negatively from an adolescent's viewpoint.Given the hundreds of millions of persons in China,many who are parents,migrating for work,there may be mental health challenges in some of the adolescents left behind.展开更多
The different solution and migration behaviors of tetrahedral and octahedral interstitial helium in bcc iron have been investigated by using first principles calculations. We showed that the tetrahedral site has less ...The different solution and migration behaviors of tetrahedral and octahedral interstitial helium in bcc iron have been investigated by using first principles calculations. We showed that the tetrahedral site has less charge transfer and less redistribution of the density of states but stronger bonding and a lower solution energy. This is due to the coupling between the symmetrical facts of the two interstitial atoms and the 3 d orbitals of Fe atoms. The solution energies of both sites are not significantly influenced by applied normal strains of 2% and 4%. In contrast, the migration barriers have the reverse trends for different migration directions under strain, which can be explained by an anisotropic elastic energy change and charge transfer. The lower migration energy along certain directions under strain can facilitate the segregation of helium and the formation of helium bubbles.展开更多
The combination of network function virtualization and software-defined networking allows various network functions to process flows according to their characteristics and requirements.Due to the highly dynamic nature...The combination of network function virtualization and software-defined networking allows various network functions to process flows according to their characteristics and requirements.Due to the highly dynamic nature of the workload,the network infrastructure needs to properly schedule the underlying resources in order to respond to workload changes in a timely manner.However,the existing NFV platform lacks a comprehensive solution for how to scale under workload variation,which may seriously hurt the overall system performance.To improve the scalability of the NFV platform and ensure consistent high performance under dynamic workloads,we propose AdaptNF,a novel NFV platform designed to support a combination of course-grained and fine-grained resource scheduling strategies.To deal with resource imbalance,which is the essential scheduling problem that leads to insufficient NFV performance,AdaptNF adopts a novel algorithm that can efficiently balance the workload among multiple network function instances through stateless flow migration.Our controlled experiments show that the AdaptNF scheme can optimize resource allocation and ensure outstanding performance after scaling.In terms of network throughput and latency,AdaptNF significantly improves the performance of the underlying NFV platform.展开更多
文摘Difunctionalization of unsaturated hydrocarbons is a pivotal synthetic strategy enabling the conversion of alkenes and alkynes into high value-added compounds.It allows for the introduction of two functional groups into the unsaturated bond in a single step,facilitating the efficient construction of complex molecular architectures,which has been widely utilized in material chemistry,pharmaceutical and fine chemical synthesis.Recently,significant progress has been made via free radical-mediated difunctionalization due to the extensive application of photocatalysis.However,highly selective difunc-tionalization reactions still remain challenging.The research progress of selective difunctionalization of unsaturated hydro-carbons using a free radical addition/functional group migration strategy over the past decade is summarized,and synthetic strategies and key reaction steps are systematically elaborated.
基金This work was supported by the Key Research and Development Program of Shandong Province(No.2019GHY112033)the National Natural Science Foundation of China(No.51609207).
文摘Atrazine causes concern due to its resistant to biodegradation and could be accumulated in aquatic organisms,causing pollution in lakes.This study measured the concentration of atrazine in ice and the water under ice through a simulated icing experiment and calculated the distribution coefficient K to characterize its migration ability in the freezing process.Furthermore,density functional theory(DFT)calculations were employed to expatiate the migration law of atrazine during icing process.According to the results,it could release more energy into the environment when atrazine staying in water phase(-15.077 kcal/mol)than staying in ice phase(-14.388 kcal/mol),therefore it was beneficial for the migration of atrazine from ice to water.This explains that during the freezing process,the concentration of atrazine in the ice was lower than that in the water.Thermodynamic calculations indicated thatwhen the temperature decreases from268 to 248 K,the internal energy contribution of the compound of atrazine and ice molecule(water cluster)decreases at the same vibrational frequency,resulting in an increase in the free energy difference of the compound from-167.946 to-165.390 kcal/mol.This demonstrated the diminished migratory capacity of atrazine.This study revealed the environmental behavior of atrazine during lake freezing,which was beneficial for the management of atrazine and other pollutants during freezing and environmental protection.
基金supported in part by the National Natural Science Foundation of China(NSFC)under grant numbers U22A2007 and 62171010the Open project of Satellite Internet Key Laboratory in 2022(Project 3:Research on Spaceborne Lightweight Core Network and Intelligent Collaboration)the Beijing Natural Science Foundation under grant number L212003.
文摘With the advancements of software defined network(SDN)and network function virtualization(NFV),service function chain(SFC)placement becomes a crucial enabler for flexible resource scheduling in low earth orbit(LEO)satellite networks.While due to the scarcity of bandwidth resources and dynamic topology of LEO satellites,the static SFC placement schemes may cause performance degradation,resource waste and even service failure.In this paper,we consider migration and establish an online migration model,especially considering the dynamic topology.Given the scarcity of bandwidth resources,the model aims to maximize the total number of accepted SFCs while incurring as little bandwidth cost of SFC transmission and migration as possible.Due to its NP-hardness,we propose a heuristic minimized dynamic SFC migration(MDSM)algorithm that only triggers the migration procedure when new SFCs are rejected.Simulation results demonstrate that MDSM achieves a performance close to the upper bound with lower complexity.
基金supported in part by NIH R01 NS100531,R01 NS103481NIH R21NS130241(to LD)+3 种基金Merit Review Award I01 BX002356,I01 BX003705 from the U.S.Department of Veterans AffairsIndiana Spinal Cord and Brain Injury Research Foundation(No.19919)Mari Hulman George Endowment Funds(to XMX)Indiana Spinal Cord&Brain Injury Research Fund from ISDH(to NKL and LD)。
文摘Schwann cell transplantation is considered one of the most promising cell-based therapy to repair injured spinal cord due to its unique growth-promoting and myelin-forming properties.A the Food and Drug Administration-approved Phase I clinical trial has been conducted to evaluate the safety of transplanted human autologous Schwann cells to treat patients with spinal cord injury.A major challenge for Schwann cell transplantation is that grafted Schwann cells are confined within the lesion cavity,and they do not migrate into the host environment due to the inhibitory barrier formed by injury-induced glial scar,thus limiting axonal reentry into the host spinal cord.Here we introduce a combinatorial strategy by suppressing the inhibitory extracellular environment with injection of lentivirus-mediated transfection of chondroitinase ABC gene at the rostral and caudal borders of the lesion site and simultaneously leveraging the repair capacity of transplanted Schwann cells in adult rats following a mid-thoracic contusive spinal cord injury.We report that when the glial scar was degraded by chondroitinase ABC at the rostral and caudal lesion borders,Schwann cells migrated for considerable distances in both rostral and caudal directions.Such Schwann cell migration led to enhanced axonal regrowth,including the serotonergic and dopaminergic axons originating from supraspinal regions,and promoted recovery of locomotor and urinary bladder functions.Importantly,the Schwann cell survival and axonal regrowth persisted up to 6 months after the injury,even when treatment was delayed for 3 months to mimic chronic spinal cord injury.These findings collectively show promising evidence for a combinatorial strategy with chondroitinase ABC and Schwann cells in promoting remodeling and recovery of function following spinal cord injury.
基金supported financially by the National Natural Science Foundation of China (U19A2018)the Key Project of Strategic New Industry of Hunan Province (2019GK2032)+2 种基金the Natural Science Foundation of Hunan Province (2021JJ30651)the Science and Technology Program of Xiangtan (GX-ZD20211004)Postgraduate Scientific Research Innovation Project of Hunan Province (CX20210635)。
文摘Lithium-rich manganese-based materials(LRMs) are promising cathode for high-energy-density lithiumion batteries due to their high capacity,low toxicity,and low cost.However,LRMs suffer from serious voltage decay and capacity fade due to continual migration and dissolution of transition metal ions(TMs) during cycling process.Herein,a novel strategy is proposed to inhibit the TMs migration of LRMs through a modified separator by means of functionalized carbon coating layer,which depends on the chemical constraint of the abundant functional groups in the modified super P.In addition,it has been found that the dissolution of TMs can be restrained based on the Le Chatelier's principle.Moreover,the modified separator owns good wettability toward the electrolyte.As a result,the LRMs cathode with the modified separator delivers a high discharge capacity of 329.93 mA h g-1 at 0.1 C,and achieves good cyclic performance,the enhanced reaction kinetics and low voltage decay.Therefore,this work provides a new idea to promote the comprehensive electrochemical performances of Li-ion batteries with LRMs cathode through a strategy of separator modification.
基金supported by National Natural Science Foundation of China (No.11175024)Beijing Natural Science Foundation of China(No.1112012)2011BAD24B01,KM201110015008,KM201010015005,PHR20110516 and PHR201107145
文摘Plasticizers that are generally used in plastics to produce flexible food packaging materials have proved to cause reproductive system problems and women＇s infertility. A long- term consumption may even cause cancer diseases. Hence a nano-scale layer, named as functional barrier layer, was deposited on the plastic surface to prevent plasticizer diethylhexyl phthalate＇s （DEHP） migration from plastics to foods. The feasibility of functional barrier layer i.e. SiOx coating through plasma enhanced chemical vapor deposition （PECVD） process was then described in this paper. We used Fourier transform infrared spectroscopy （FTIR） to analyze the chemical composition of coatings, scanning electron microscope （SEM） to explore the topography of the coating surfaces, surface profilemeter to measure thickness of coatings, and high-performance liquid chromatography （HPLC） to evaluate the barrier properties of coatings. The results have clearly shown that the coatings can perfectly block the migration of the DEHP from plastics to their containers. It is also concluded that process parameters significantly influence the block efficiency of the coatings. When the deposition conditions of SiOx coatings were optimized, i.e. 50 W of the discharge power, 4 ： 1 of ratio of O2 ： HMDSO, and ca.100 nm thickness of SiOx, 71.2% of the DEHP was effectively blocked.
基金supported by the National Natural Science Foundation of China (Grant No.10974183)
文摘Oxygen vacancy formation and migration in La0.9Sr0.1Ga0.8Mg0.2O3-5 （LSGM） with various crystal symmetries （cubic, rhombohedral, orthorhombic, and monoclinic） are studied by employing first-principles calculations based on density functional theory （DFT）. It is shown that the cubic LSGM has the smallest band gap, oxygen vacancy formation energy, and migration barrier, while the other three structures give rise to much larger values for these quantities, implying the best oxygen ion conductivity of the cubic LSGM among the four crystal structures. In out calculations, one oxygen vacancy migration pathway is considered in the cubic and rhombohedral structures due to all the oxygen sites being equivalent in them, while two vacancy migration pathways with different migration barriers are found in the orthorhombic and monoclinic symmetries owing to the existence of nonequivalent O1 and 02 oxygen sites. The migration energies along the migration pathway linking the two 02 sites are obviously lower than those along the pathway linking the O1 and 02 sites. Considering the phase transitions at high temperatures, the results obtained in this paper can not only explain the experimentally observed different behaviours of the oxygen ionic conductivity of LSGM with different symmetries, but also predict the rational crystal structures of LSGM for solid oxide fuel cell applications.
基金supported by the National Natural Science Foundation of China,Nos.82272171(to ZY),82271403(to XL),81941011(to XL),31971279(to ZY),31730030(to XL)the Natural Science Foundation of Beijing,No.7222004(to HD).
文摘The presence of endogenous neural stem/progenitor cells in the adult mammalian brain suggests that the central nervous system can be repaired and regenerated after injury.However,whether it is possible to stimulate neurogenesis and reconstruct cortical layers II to VI in non-neurogenic regions,such as the cortex,remains unknown.In this study,we implanted a hyaluronic acid collagen gel loaded with basic fibroblast growth factor into the motor cortex immediately following traumatic injury.Our findings reveal that this gel effectively stimulated the proliferation and migration of endogenous neural stem/progenitor cells,as well as their differentiation into mature and functionally integrated neurons.Importantly,these new neurons reconstructed the architecture of cortical layers II to VI,integrated into the existing neural circuitry,and ultimately led to improved brain function.These findings offer novel insight into potential clinical treatments for traumatic cerebral cortex injuries.
基金financially co-supported by the National 973 Project of China(Nos.2014CB239006,2011CB202402)the National Natural Science Foundation of China(Nos.41104069,41274124)+1 种基金the Natural Science Foundation of Shandong Province(No.ZR2011DQ016)the Fundamental Research Funds for the Central Universities of China(No.R1401005A)
文摘Elastic migration has been widely paid attention by employing the vector processing of mul- ticomponent seismic data. Ray based elastic Kirchhoff migration has such properties as high flexibility and high efficiency. However, it has failed to solve many problems caused by multipath. On the other hand, elastic reverse-time migration （RTM） based on the two-way wave equation is known to be capable of dealing with these problems, but it is extremely expensive when applied in 3D cases and velocity model building. Based on the elastic Kirchhoff-Helmholtz integral, we calculate deeoupled backward-continued wavefields by introducing elastic Green functions for P- and S-waves, which is expressed by a summation of elastodynamic Gaussian beams. The PP and polarity-corrected PS images are obtained by calculating the correlation between downward and deeoupled backward-continued vector wavefields, where polarity correction is performed by analyzing the relation between the polarization direction of converted PS waves and incident angle on the interface. To a large extent, our method combines the high efficiency of ray-based migration with the high accuracy of wave-equation based reverse-time migration. Application of this method to multicomponent synthetic datasets from the fault model and Marmousi 2 model demonstrates the validity, flexibility and accuracy of the new method.
基金Supported by Partially by Deutsche Forschungsgemeinschaft,DFG GA 785/5-1 and Deutsche Krebshilfe,GA 109313
文摘AIM:To hypothesize that beta-7 integrin affects cellularmigration of both,lymphocytes and enterocytes.METHODS:The nucleoside analog Brd U was ip injected in beta-7-deficient mice(C57BL/6-Itgbtmlcgn/J)of male gender and age-matched male C57BL/J J mice(wild type)4,20,or 40 h before analysis.The total small intestine was isolated,dissected,and used for morphometrical studies.Brd U-positive epithelial cells were numbered in at least 15 hemi-crypts per duodenum,jejunum,and ileum of each animal.The outer most Brd U-positive cell(cellmax)was determined per hemi-crypt,numerically documented,and statistically analysed.RESULTS:Integrins containing the beta-7-chain were exclusively expressed on leukocytes.In the small intestinal mucosa of beta-7 integrin-deficient mice the number of intraepithelial lymphocytes was drastically decreased.Moreover,the Peyer’s patches of beta-7integrin-deficient mice appeared hypoplastic.In beta-7integrin-deficient mice the location of cellmax was found in a higher position than it was the case for the controls.The difference was already detected at 4 h after Brd U application,but significantly increased with time(40 h after Brd U injection)in all small intestinal segments investigated,i.e.,duodenum,jejunum,and ileum.Migration of small intestinal enterocytes was different between the experimental groups measured by cellmax locations.CONCLUSION:The E-cadherin beta-7 integrin pathway probably controls migration of enterocytes within the small intestinal surface lining epithelial layer.
基金supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions of China
文摘MicroRNAs refer to a class of endogenous,short non-coding RNAs that mediate numerous biological functions.MicroRNAs regulate various physiological and pathological activities of peripheral nerves,including peripheral nerve repair and regeneration.Previously,using a rat sciatic nerve injury model,we identified many functionally annotated novel microRNAs,including miR-sc14.Here,we used real-time reverse transcription-polymerase chain reaction to examine miR-sc14 expression in rat sciatic nerve stumps.Our results show that miRsc14 is noticeably altered following sciatic nerve injury,being up-regulated at 1 day and diminished at 7 days.EdU and transwell chamber assay results showed that miR-sc14 mimic promoted proliferation and migration of Schwann cells,while miR-sc14 inhiThe study was approved by the Jiangsu Provincial Laboratory Animal Management Committee,China on March 4,2015(approval No.20150304-004).bitor suppressed their proliferation and migration.Additionally,bioinformatic analysis examined potential target genes of miR-sc14,and found that fibroblast growth factor receptor 2 might be a potential target gene.Specifically,our results show changes of miR-sc14 expression in the sciatic nerve of rats at different time points after nerve injury.Appropriately,up-regulation of miR-sc14 promoted proliferation and migration of Schwann cells.Consequently,miR-sc14 may be an intervention target to promote repair of peripheral nerve injury.The study was approved by the Jiangsu Provincial Laboratory Animal Management Committee,China on March 4,2015(approval No.20150304-004).
基金Supported by Deutsche Forschungsgemeinschaft,No.DFG GA 785/5-1(partially)Deutsche Krebshilfe,No.GA 109313(partially)
文摘AIM: To verify the hypothesis that caspase-8(Casp8), which regulates cellular apoptosis and necroptosis, is critically involved in enterocyte migration.METHODS: Casp8-silenced Caco2 cells were used in migration assays. In addition, enterocyte-specific Casp8 heterozygous(Casp8+/?int) or homozygous knockout mice(Casp8?int) were generated by crossing genetically modified mice carrying lox P recombination sites in intron 2 and 4 of the murine Casp8 gene with transgenic animals expressing a cre-transgene under control of the villin promoter in a pure C57/BL6 genetic background. The nucleoside analog Brd U was injected i.p. in male Casp8+/?int and Casp8?int animals 4 h, 20 h, or 40 h before performing morphometric studies. Locations of anti-Brd U-immunostained cells(cellmax) in at least 50 hemi-crypts of 6 histoanatomically distinct intestinal mucosal regions were numbered and extracted for statistical procedures. For the mice cohort(n = 28), the walking distance of enterocytes was evaluated from cellmax within crypt(n = 57), plateau(n = 19), and villus(n = 172) positions, resulting in a total of 6838 observations. Data analysis was performed by fitting a three-level mixed effects modelto the data.RESULTS: In cell culture experiments with Caco2 cells, Casp8 knockdown efficiency mediated by RNA interference on Casp8 transcripts was 80% controlled as determined by Western blotting. In the scratch assay, migration of Casp8-deleted Caco2 cells was significantly diminished when compared with controls(Casp8?scramble and Caco2). In Brd U-labeled Casp8?int mice, cellmax locations were found along the hemi-crypts in a lower position than it was for Casp8+/?int or control(cre-negative) animals. Statistical data analysis with a three-level mixed effects model revealed that in the six different intestinal locations(distinct segments of the small and large intestine), cell movement between the three mice groups differed widely. Especially in duodenal hemi-crypts, enterocyte movement was different between the groups. At 20 h, duodenal cellmax location was significantly lower in Casp8?int(25.67 ± 2.49) than in Casp8+/?int(35.67 ± 4.78; P < 0.05) or control littermates(44.33 ± 0.94; P < 0.01).CONCLUSION: C a s p 8- d e p e n d e n t m i g ra t i o n o f enterocytes is likely involved in intestinal physiology and inflammation-related pathophysiology.
文摘BACKGROUND Stroke is a common cause of neurological dysfunction,often resulting in hemiplegia.Thus,rehabilitation of limb function in stroke patients is an important step towards accelerating recovery and improving quality of life.AIM To investigate whether unilateral strength training in hemiplegic stroke patients could lead to cross-migration,an increase in bilateral muscle strength,and an improvement in lower limb motor function.METHODS We randomly divided 120 patients with hemiplegic stroke into two groups:Eexperimental and control groups,with 60 patients in each group.Both groups received routine rehabilitation treatment,while the experimental group additional-ly received ankle dorsiflexion resistance training on the healthy side for 6 wk.We measured the maximum voluntary contract(MVC),changes in surface electromyography(EMG),and the lower limb motor function using the simplified Fugl Meyer Motor Function Assessment Scale(FMA)before and within 1 wk after training.RESULTS The FMA score in the experimental group improved significantly compared to both their pre-training score and the control group's post-training score(P<0.05).The integrated EMG of the anterior tibialis muscle and pulmonary intestine muscle in the experimental group were significantly different after training than before(P<0.05).Furthermore,the MVC of the anterior tibialis muscle on both the healthy and affected sides and the MVC of the pulmonary intestine muscle on both sides showed significant improvement compared with before training and the control group(P<0.05).CONCLUSION Our findings suggest that ankle dorsiflexion resistance training on the healthy side in hemiplegic stroke patients can increase strength in the opposite tibialis anterior muscle and antagonist's muscle,indicating a cross-migration phenomenon of strength training.Furthermore,this type of training can also improve lower limb motor function,providing a new exercise method for improving early ankle dorsiflexion dysfunction.
基金This project is sponsored by the National Natural Science Foundation （40474041）, CNPC Young Innovation Fund （04E7040）, the Post-doctoral Research Station of Zhongyuan 0ilfield, Jiangsu 0ilfield, and CNPC Geophysical Laboratories at the China University of Petroleum （East China）.
文摘Beamlet sources have strong local and directional character and can easily accomplish local illumination and migration. Besides, they provide better migration results than conventional migration methods. We introduce the basic principles of beamlet prestack depth migration that includes a windowed Fourier transform and frame theory. We explain the Gabor-Daubechies （G-D） frame based on a Gaussian function. Beamlet decomposition provides information on the local space and direction of wavefield. We synthesize the beamlet source and beamlet records in the wavelet domain using both rectangle and Gaussian windows and then extrapolate the synthesized data with a Fourier finite-difference operator. We test the method using the standard Marmousi model. By comparing and analyzing the migration results of single directional beamlet and beamlets with different windows and directions, we demonstrate the validity of the prestack depth migration with Gaussian beamlets method.
基金The Second Tibetan Plateau Scientific Expedition and Research Program(No.2019QZKK0501)National Natural Science Foundation of China(No.31772478,31501851).
文摘Altitudinal bird migration involves seasonal shifts up and down the altitude gradient annually.Asia as the place with the largest number of altitudinal migrants,has quite few related studies,especially for montane and temperate avifaunas.To explore the potential drivers of seasonal altitudinal migration for birds in the middle of Hengduan Mountains,we conducted a three-year investigation on breeding and non-breeding season bird communities at eight elevational bands(1200–4200 m)in the Gongga Mountains.We examined the altitudinal migration patterns and relationships between seasonal distribution shifts and species'traits of 50 species with sufficient data recorded in both seasons.We found that a large proportion of breeding birds underwent altitudinal migration and showed three migration patterns(downslope shift,upslope shift,no shift).Seasonal distribution shifts were mainly correlated with certain ecological traits.Species breeding at high and mid-elevations,nesting in scrub and being omnivorous are more likely to show downslope movements during the non-breeding season.In addition,territorially weaker species exhibited more diverse migration patterns.Notably,we found the hand-wing index(HWI)was actually more convincing than body mass in explaining altitudinal migration.These results consolidate the studies of seasonal altitudinal migration in montane birds.Our study could be used to bridge existing knowledge gaps that currently impeding effective conservation for montane avifaunas in the Hengduan Mountains.
基金supported by Sub Four Programme of Public Health Welfare Research Special Funds[grants No.201202010]Natural Science Fund Commission of China[H2609/81673232]the Yale Center for Interdisciplinary Research on Acquired Immune Deficiency Syndrome supported by National Institutes of Health grant[P30MH062294]
文摘We sought to identify the differences between adolescents left behind in their home villages/towns(LBA)and non-left behind adolescents(NLB)on subjective well-being and family functioning due to parental migration in south China.We used a stratified cluster sampling method to recruit middle school students in a city experiencing population-emigration in Jiangxi Province in 2010.Participants included adolescents from families with:(1)one migrant parent,(2)both parents who migrated,or(3)non-left behind adolescents(i.e.,no migrant parent).To determine predictors of subjective well-being,we used structural equation models.Adolescents left behind by both parents(LBB)were less likely to express life satisfaction(P=0.038)in terms of their environments(P=0.011)compared with NLB.A parent or parents who migrated predicts lower subjective well-being of adolescents(P=0.051)and also lower academic performance.Being apart from their parents may affect family functioning negatively from an adolescent's viewpoint.Given the hundreds of millions of persons in China,many who are parents,migrating for work,there may be mental health challenges in some of the adolescents left behind.
基金supported by the National Basic Research Programs of China (Nos. 2015GB118001, 2015CB654802, 20151080369 and 20141300796)
文摘The different solution and migration behaviors of tetrahedral and octahedral interstitial helium in bcc iron have been investigated by using first principles calculations. We showed that the tetrahedral site has less charge transfer and less redistribution of the density of states but stronger bonding and a lower solution energy. This is due to the coupling between the symmetrical facts of the two interstitial atoms and the 3 d orbitals of Fe atoms. The solution energies of both sites are not significantly influenced by applied normal strains of 2% and 4%. In contrast, the migration barriers have the reverse trends for different migration directions under strain, which can be explained by an anisotropic elastic energy change and charge transfer. The lower migration energy along certain directions under strain can facilitate the segregation of helium and the formation of helium bubbles.
基金supported by the Guangdong Province Key Area R&D Program under grant No.2018B010113001National Key Research and Development Program of China under Grant No.2018YFB1804704+1 种基金National Natural Science Foundation of China under grant No.61902171the Shenzhen Key Lab of Software Defined Networking under grant No.ZDSYS20140509172959989.
文摘The combination of network function virtualization and software-defined networking allows various network functions to process flows according to their characteristics and requirements.Due to the highly dynamic nature of the workload,the network infrastructure needs to properly schedule the underlying resources in order to respond to workload changes in a timely manner.However,the existing NFV platform lacks a comprehensive solution for how to scale under workload variation,which may seriously hurt the overall system performance.To improve the scalability of the NFV platform and ensure consistent high performance under dynamic workloads,we propose AdaptNF,a novel NFV platform designed to support a combination of course-grained and fine-grained resource scheduling strategies.To deal with resource imbalance,which is the essential scheduling problem that leads to insufficient NFV performance,AdaptNF adopts a novel algorithm that can efficiently balance the workload among multiple network function instances through stateless flow migration.Our controlled experiments show that the AdaptNF scheme can optimize resource allocation and ensure outstanding performance after scaling.In terms of network throughput and latency,AdaptNF significantly improves the performance of the underlying NFV platform.
