Non-spherical particles exist widely in natural and industrial fluid systems and the motions of nonspherical particles are significantly different from that of spherical particles.In this paper,a simplified model of n...Non-spherical particles exist widely in natural and industrial fluid systems and the motions of nonspherical particles are significantly different from that of spherical particles.In this paper,a simplified model of non-spherical particles considering particle drag correction,lift,and rotation was established.Based on the Eulerian-Lagrangian simulation,the dispersion characteristics of spherical and nonspherical particles with different Stokes numbers in a high-speed turbulent jet were analyzed and compared considering the effect of particle rotation.The results show that,the differences in particle dispersion and radial velocity fluctuation between non-spherical particles and spherical particles in the jet are significant,especially when Stokes number is large.Moreover,the effects of different type of forces on the dispersion of non-spherical particles and spherical particles were compared in detail,which revealed that the change of the Magnus force caused by the increase in the angular velocity of non-spherical particles plays a dominant role in the differences of particle dispersion.展开更多
Non-adherent bone marrow cell-derived mesenchymal stem cells from C57BL/6J mice were sepa- rated and cultured using the ＂pour-off＂ method. Non-adherent bone marrow cell-derived mesen- chymal stem ceils developed col...Non-adherent bone marrow cell-derived mesenchymal stem cells from C57BL/6J mice were sepa- rated and cultured using the ＂pour-off＂ method. Non-adherent bone marrow cell-derived mesen- chymal stem ceils developed colony-forming unit-fibroblasts, and could be expanded by supple- mentation with epidermal growth factor. Immunocytochemistry showed that the non-adherent bone marrow cell-derived mesenchymal stem cells exposed to basic fibroblast growth factor/epidermal growth factor/nerve growth factor expressed the neuron specific markers, neurofilament-200 and NeuN, in vitro. Non-adherent bone marrow cell-derived mesenchymal stem cells from 13-galactosidase transgenic mice were also transplanted into focal ischemic brain （right corpus striatum） of C57BL/6J mice. At 8 weeks, cells positive for LacZ and 13-galactosidase staining were observed in the ischemic tissues, and cells co-labeled with both 13-galactosidase and NeuN were seen by double immunohistochemical staining. These findings suggest that the non-adherent bone marrow cell-derived mesenchymal stem cells could differentiate into neuronal-like cells in vitro and in vivo.展开更多
Drop size distribution(DSD) or mean droplet size(d32) and liquid holdup are two key parameters in a liquid–liquid extraction process. Understanding and accurately predicting those parameters are of great importance i...Drop size distribution(DSD) or mean droplet size(d32) and liquid holdup are two key parameters in a liquid–liquid extraction process. Understanding and accurately predicting those parameters are of great importance in the optimal design of extraction columns as well as mixer–settlers. In this paper, the method of built-in endoscopic probe combined with pulse laser was adopted to measure the droplet size in liquid–liquid dispersions with a pump-impeller in a rectangular mixer. The dispersion law of droplets with holdup range 1% to 24% in batch process and larger flow ratio range 1/5 to 5/1 in continuous process was studied. Under the batch operation condition, the DSD abided by log-normal distribution. With the increase of impeller speed or decrease of dispersed phase holdup, the d32 decreased. In addition, a prediction model of d32 of kerosene/deionized system was established as d32/D = 0.13(1 + 5.9φ)We-0.6. Under the continuous operation condition, the general model for droplet size prediction of kerosene/water system was presented as d32/D = C3(1 + C4φ)We-0.6. For the surfactant system and extraction system, the prediction models met a general model as d32/D = bφnWe-0.6.展开更多
Objective:Hepatocellular carcinoma(HCC)is a severely lethal cancer that usually originates from chronic liver injury and inflammation.Although progress on diagnosis and treatment is obvious,the cause of HCC remains un...Objective:Hepatocellular carcinoma(HCC)is a severely lethal cancer that usually originates from chronic liver injury and inflammation.Although progress on diagnosis and treatment is obvious,the cause of HCC remains unclear.In this study,we sought to determine key genes in HCC development.Methods:To identify key regulators during HCC progression,we performed transcriptome sequencing to obtain time series gene expression data from a mouse model with diethylnitrosamine-induced liver tumors and further verified gene expression and function in vitro and in vivo.Results:Among the differentially expressed genes,Cyp2c29 was continuously downregulated during HCC progression.Overexpression of Cyp2c29 suppressed N F-kB activation and proinflammatory cytokine production by increasing the production o f 14,15-epoxyeicosatrienoic acid in vitro.Furthermore,overexpression of Cyp2c29 in vivo protected against liver inflammation in mouse models of liver injury induced by both acetaminophen and CC14.Two human homologs of mouse Cyp2c29,CYP2C8 and CYP2C9,were found to be downregulated in human HCC progression,and their expression was positively correlated with overall survival in patients with HCC(significance:P=0.046 and 0.0097,respectively).Conclusions:Collectively,through systematic analysis and verification,we determined that C yp2c29 is a novel gene involved in liver injury and inflammation,which may be a potential biomarker for HCC prevention and prognosis determination.展开更多
Utilization of carbon dioxide(CO_(2)) is of great significance in the development of CO_(2) absorption and the solution of greenhouse gas effect.Highly efficient conversion of CO_(2) into cyclic carbonate with green c...Utilization of carbon dioxide(CO_(2)) is of great significance in the development of CO_(2) absorption and the solution of greenhouse gas effect.Highly efficient conversion of CO_(2) into cyclic carbonate with green catalysts is essential for the more sustainable expansion of CO_(2) fixation.Traditional batch reactor is limited by low efficiency, high cost and low security. Meanwhile, continuous flow system showcased a myriad of virtues, including shortening the residence time from hours to seconds, and decreasing reaction temperature, and possessing the nature of easy industrial scale-up. In this paper, a continuous-flow microreaction system was developed to synthesis propylene carbonate(PC) from propylene oxide(PO) and CO_(2) using 1-butyl-3-methylimidazolium bromide([BMIM]Br) as catalyst. By observing the flow patterns inside microreaction system, the effects of reaction temperature, molar fraction of catalyst, operating pressure, residence time, molar ratio of CO_(2)/PO as well as recycling performance of catalyst on the overall performances were comprehensively evaluated into details. Under different reaction conditions,the flow patterns were set to vary between slug flow and annular flow. The results showed that the yield of propylene carbonate(PC) can reach99.7% at 140℃ and 3.0 MPa with the residence time of 166 s, while the recycling performance of the designed system greatly conforms the future trend of green chemistry.展开更多
The classification performance of model coal mill classifiers with different bottom incoming flow inlets was experimentally and numerically studied.The flow field adjacent to two neighboring impeller blades was measur...The classification performance of model coal mill classifiers with different bottom incoming flow inlets was experimentally and numerically studied.The flow field adjacent to two neighboring impeller blades was measured using the particle image velocimetry technique.The results showed that the flow field adjacent to two neighboring blades with the swirling inlet was significantly different from that with the non-swirling inlet.With the swirling inlet,there was a vortex located between two neighboring blades,while with the nonswirling inlet,the vortex was attached to the blade tip.The vorticity of the vortex with the non-swirling inlet was much lower than that with the swirling inlet.The classifier with the non-swirling inlet demonstrated a larger cut size than that with the swirling inlet when the impeller was stationary(~0 r·min-1).As the impeller rotational speed increased,the cut size of the cases with non-swirling and swirling inlets both decreased,and the one with the non-swirling inlet decreased more dramatically.The values of the cut size of the two classifiers were close to each other at a high impeller rotational speed(≥120 r·min-1).The overall separation efficiency of the classifier with the non-swirling inlet was lower than that with the swirling inlet,and monotonically increased as the impeller rotational speed increased.With the swirling inlet,the overall separation efficiency first increased with the impeller rotational speed and then decreased when the rotational speed was above 120 r·min-1,and the variation trend of the separation efficiency was more moderate.As the initial particle concentration increased,the cut sizes of both swirling and non-swirling inlet cases decreased first and then barely changed.At a low initial particle concentration(b 0.04 kg·m-3),the classifier with the swirling inlet had a larger cut size than that with the non-swirling inlet.展开更多
Signed networks refer to a class of network systems including not only cooperative but also antagonistic interactions among nodes.Due to the existence of antagonistic interactions in signed networks,the agreement of n...Signed networks refer to a class of network systems including not only cooperative but also antagonistic interactions among nodes.Due to the existence of antagonistic interactions in signed networks,the agreement of nodes may not be established,instead of which disagreement behaviors generally emerge.This paper reviews several different disagreement behaviors in signed networks under the single-integrator linear dynamics,where two classes of topologies,namely,the static topology and the dynamic topology,are considered.For the static signed networks with the adjacency weights as(time-varying)scalars,we investigate the convergence behaviors and the fluctuation behaviors with respect to fixed topologies and switching topologies,respectively,and give some brief introductions on the disagreement behaviors of general time-varying signed networks.Correspondingly,several classes of behavior analysis approaches are also provided.For the dynamic signed networks with the adjacency weights as transfer functions or linear time-invariant systems,we show the specific descriptions and characteristics of them such that the disagreement behaviors can be obtained by resorting to the derived static signed graphs.Furthermore,we give their applications to the behavior analysis of static signed networks in the presence of high-order dynamics or communication delays.展开更多
Carbon dioxide(CO_(2))utilization and fixation have become one of the most important research areas nowadays due to the increase of global greenhouse effect.Cyclic carbonate,which is widely used in various fields,can ...Carbon dioxide(CO_(2))utilization and fixation have become one of the most important research areas nowadays due to the increase of global greenhouse effect.Cyclic carbonate,which is widely used in various fields,can be synthesized by fixation of CO_(2) with epoxide in industry.Moreover,the synthesis of cyclic carbonate is a 100%atom economical reaction,which makes it eco-friendly and promising.To enhance the reaction efficiency and safety,a microreaction system was used as the platform for cycloaddition reaction.In this work,tetrabutylammonium bromide(TBAB)was chosen as catalyst,and propylene oxide(PO)as a mode substrate.Interestingly,the addition of water can increase the propylene carbonate(PC)yield and decrease the activation energy considerably,proving water as catalyst promoter for PC synthesis.PC yield and selectivity could reach 91.6%and 99.8%,respectively.The Influence factors and kinetic equation for CO_(2) cycloaddition were obtained as well.展开更多
The indoor thermal history of residents in the hot summer and cold winter climate zone in China have undergone a significant change in recent years,which also changes their seasonal thermal adaptations and this has fo...The indoor thermal history of residents in the hot summer and cold winter climate zone in China have undergone a significant change in recent years,which also changes their seasonal thermal adaptations and this has formed feed-back effects to the increasing usage of air conditioning units in this area.To study the seasonal variations of thermal adaptation,the thermal comfort experiments were conducted on two groups of participants.Each groups included 20 participants who had indoor history mainly with natural ventilation(NV group)and air-conditioning(AC group),respectively.The results demonstrated that the thermal sensation vote(TSV)in warm environments did not differ between AC and NV subjects in summer.However,the TSV of AC subjects were much lower than that of NV subjects in the same standard effective temperature and skin temperature in a cold environment in winter.Overall,the participants who spent most of their time in AC space in winter showed a low level of thermal adaptation with a narrower acceptable skin temperature range of 32.6-33.5℃.Thus,this study presents the basic information regarding the seasonal effects on human thermal adaptation due to different long-term indoor thermal histories.展开更多
Supported Pd catalysts show superior activities for olefin productions from alkynes through semi-hydrogenation reactions,but over-hydrogenation into alkanes highly decreases olefin selectivity.Using phenylacetylene se...Supported Pd catalysts show superior activities for olefin productions from alkynes through semi-hydrogenation reactions,but over-hydrogenation into alkanes highly decreases olefin selectivity.Using phenylacetylene semi-hydrogenation as a model reaction,here we explore the optimization approaches toward better Pd catalysts for alkyne semi-hydrogenation through investigating support effect and metal-support interactions.The results show that the states of Pd with supports can be tuned by varying oxide reducibility,loading ratios,and post-treatments.In our system,0.06 wt.%Pd on rutile-TiO_(2) nanorods shows the highest activity owing to the synergistic effects of single-atoms and clusters.Support reducibility can change the filling degrees of Pd 4d orbitals through varying interfacial bonding strengths,which further affect catalytic activity and selectivity.展开更多
Understanding the influencing mechanism of turbulent fluctuation on the ignition characteristics of millimeter coal particles is essential.In this work,to study the effect of turbulent fluctuation on ignition time,mil...Understanding the influencing mechanism of turbulent fluctuation on the ignition characteristics of millimeter coal particles is essential.In this work,to study the effect of turbulent fluctuation on ignition time,millimeter coal particles are subjected to a specific flow field,generated in a furnace with symmetric fans.A one-dimensional model with the new proposed correlation and the Ranz-Marshall(R-M)correlation for Nu(Nusselt number)is established to simulate the coal ignition process.In addition,the effects of fan speed,temperature,particle diameter,particle distance and coal type on the ignition time are investigated.It is found that an increase in fan speed from 0 to 3000 rpm leads to a particle Reynolds number Re_(p)increase from 0 to 22.5,and a turbulent particle Reynolds number Re_(t)*increase from 0 to 71.5.With a consideration of the fluctuation effect,the new correlation of Nu gives a better prediction of ignition time compared to the R-M correlation.Moreover,the ignition time is revealed to decrease with an increasing fan speed and an elevating temperature.While the ignition time shows merely an initial boost with enlarging particle distance,it exhibits a linearity with the term of particle diameter dp1.3-1.7 and Reynolds numbers(Nu*/Nu)-0.6(Nu*is turbulent Nusselt number).Based on this relationship,the difference of predicted ignition time is calculated at different Re_(p)and Re_(t)*.It is shown that at low Re_(p)or high Re_(t)*values,the new correlation should substitute for the R-M correlation.展开更多
Objective The study aimed to explore the association between the site of interictal epileptic discharges(IEDs)on postoperative electroencephalogram(EEG)and seizure recurrence after antiepileptic drug(AED)withdrawal.Th...Objective The study aimed to explore the association between the site of interictal epileptic discharges(IEDs)on postoperative electroencephalogram(EEG)and seizure recurrence after antiepileptic drug(AED)withdrawal.The study hypothesizes that the concordance of IED sites with surgical sites indicates incomplete resection of epileptic focus,while non-concordance of IED sites with surgical sites indicates postoperative changes or cortical stimulation.The former has a higher risk of seizure recurrence.Methods We retrospectively analyzed the postoperative EEG pattern of 182 consecutive children who underwent resection surgery.To identify the risk factors for seizure recurrence,we compared the attributes of seizure recurred and seizure-free groups by univariate and multivariate analyses.AED tapering was standardized,involving a 25% reduction in the dose of a single type of AED every 2 weeks,independent of the presurgical AED load.Results We attempted AED withdrawal in 116(63.7%)children.Twenty-eight(24.1%)children experienced seizure recurrence during or after AED withdrawal.A greater number of AEDs used at the time of surgery(p=0.005),incomplete resection(p=0.001),and presence of IED on postoperative EEG(p=0.011)are predictors of seizurerecurrence.Thecompletenessof resectionand seizure recurrence after AED withdrawal were related to the presence of IED on the EEG,but not to the concordance of IED with surgical sites.Conclusion For children with abnormal EEG,the decision to discontinue AED should be made more cautiously,regardless of the relative location of the discharge site and the surgical site.展开更多
The present paper explores how the issue of the current energy crisis in the wake of the Covid-19 and Ukraine war was constructed by political cartoons.Adopting Critical Multimodal Metaphor Scenario Analysis,this pape...The present paper explores how the issue of the current energy crisis in the wake of the Covid-19 and Ukraine war was constructed by political cartoons.Adopting Critical Multimodal Metaphor Scenario Analysis,this paper focuses on the DISEASE metaphor scenario,one of the most recurring scenarios in political cartoons on this topic,and specifically emphasizes how the METHOD OF TREATMENT,one of the structural elements in the scenario,is represented.The analysis reveals that two predominant scenarios cOnstitute the representations of the METHOD OF TREATMENT:NARCOTIC Scenario and MEDICINE scenario.They differ in entailments:one frames fossil energy as detrimental narcotic while the other frames it as therapeutic medicine.By means of the two scenarios,these cartoons convey strong criticism of the major involvers in the energy crisis,namely,the E.U.,Russia,and the U.S.The cartoons make full use of the dynamic interplay of visual and/or verbal metonymy,metaphor,and narrative to elicit associations,assumptions and evaluations in the viewers,helping facilitate understanding and constructing a view of the crisis reality.The present analysis sheds light on the way cartoonists reshape the public point of view in the framing of specific event(s).展开更多
Considering the percentage of dissatisfied due to local thermal sensation(PD LTSV),a vertical air temperature difference(ΔT_(d))threshold of about 3°C was recommended in standards.However,some novel air distribu...Considering the percentage of dissatisfied due to local thermal sensation(PD LTSV),a vertical air temperature difference(ΔT_(d))threshold of about 3°C was recommended in standards.However,some novel air distribution methods might create large positive(which means the head warmer than the feet,vice versa)or negativeΔT_(d),with no suitable proved criteria to be used.In this study,sixteen subjects were seated in a climatic box placed in a climate chamber to evaluate thermal sensation and percentage of dissatisfied with negative and positiveΔT_(d) in different whole-body thermal conditions.Air temperatures were controlled independently at the upper and lower body parts,with 13 different air temperature sets combined with 22°C,25°C,28°C,and 31°C(i.e.-9°C≤ΔT_(d)≤9°C).Results showed that subjects were more thermally sensitive at the upper body and with positiveΔT_(d) than at the lower body or with negativeΔT_(d).The 80%acceptableΔT_(d) range is about-8 to 7°C in overall neutral(TSV=0),-7°C to 6°C in slightly cool(TSV=-0.5)conditions,which is wider than-3 to 3°C in slightly warm conditions(TSV=+0.5).By considering the factors of both TSV andΔT_(d),a new overall percentage of dissatisfied index(OPD P)was proposed.Case studies show that the new OPD P index is more precise and suitable for the evaluations of different air distributions to predict overall percentage of dissatisfied in thermal environments with vertical air temperature difference.展开更多
Some eclogites and the related high-P metamorphic belt have been found for the first time from the Tongbai Mountains, Henan Province, where the eclogites and their probable retrogressive products —— garnet amphiboli...Some eclogites and the related high-P metamorphic belt have been found for the first time from the Tongbai Mountains, Henan Province, where the eclogites and their probable retrogressive products —— garnet amphibolites —— occur as lenses in mica-schists. The fresheclogites comprise garnet, omphacite, quartz, rutile, phengite, barroisite, etc. The composi-展开更多
Individual thermal comfort models based on physiological parameters could improve the efficiency of the personal thermal comfort control system.However,the effect of thermal history has not been fully addressed in the...Individual thermal comfort models based on physiological parameters could improve the efficiency of the personal thermal comfort control system.However,the effect of thermal history has not been fully addressed in these models.In this study,climate chamber experiments were conducted in winter using 32 subjects who have different indoor and outdoor thermal histories.Two kinds of thermal conditions were investigated:the temperature dropping(24-16℃)and severe cold(12℃)conditions.A simplified method using historical air temperature to quantify the thermal history was proposed and used to predict thermal comfort and thermal demand from physical or physiological parameters.Results show the accuracies of individual thermal sensation prediction was low to about 30%by using the PMV index in cold environments of this study.Base on the sensitivity and reliability of physiological responses,five local skin temperatures(at hand,calf,head,arm and thigh)and the heart rate are optimal input parameters for the individual thermal comfort model.With the proposed historical air temperature as an additional input,the general accuracies using classification tree model C5.0 were increased up by 15.5%for thermal comfort prediction and up by 29.8%for thermal demand prediction.Thus,when predicting thermal demands in winter,the factor of thermal history should be considered.展开更多
Global warming and climate change due to anthropogenic carbon dioxide(CO_(2))have aroused significant concerns at the global scale due to rapid economic growth in industries and other fields.Therefore,CO_(2)capture,us...Global warming and climate change due to anthropogenic carbon dioxide(CO_(2))have aroused significant concerns at the global scale due to rapid economic growth in industries and other fields.Therefore,CO_(2)capture,use,and storage have become particularly important.In this review,general background and methods for CO_(2)capture and separation,in particular,on ionic liquids(ILs)-based solvents and materials,are discussed.Comprehensive surveys of ILs for CO_(2)absorption are presented,which focused mainly on experimental researches,and then the concept is extended to functionalized absorbents and recent developments for CO_(2)capture.Major advantages and disadvantages of amines-based and ILs-based absorbents are discussed in this review.Solutions of traditional amines(MEA,MDEA,DEA,AMP,PZ,etc.)and ILs(conventional ILs,functionalized ILs,etc.)are summarized.Moreover,research progresses on CO_(2)separation are also introduced focusing mainly on amines and ILs-based membranes(e.g.supported amines membranes,SILMs).Futhermore,the fixation of CO_(2)into cyclic carbonates catalyzed by ILs(pure ILs,complex catalyst system with ILs,supported ILs,etc.)is summarized,clearly explaining the mechanism of CO_(2)fixation with ILs.Finally,exploration of some recent studies about CO_(2)capture and conversion by ILs and challenges for further progress are presented and related suggestions are put forward.展开更多
In this paper,the design and operation of a novel coal-fired circulating fluidized bed(CFB)drum boiler that can generate superheated steam using saline water were introduced.The natural circulation water dynamics with...In this paper,the design and operation of a novel coal-fired circulating fluidized bed(CFB)drum boiler that can generate superheated steam using saline water were introduced.The natural circulation water dynamics with a drum was adopted instead of the traditional once-through steam generator(OTSG)design,so that superheated steam can be generated for the better performance of the steam assisted gravity drainage(SAGD)technology in heavy oil recovery.The optimized staged evaporation method was proposed to further decrease the salinity of water in the clean water section of the boiler.The evaporating pipes of the salted water section were rearranged in the back pass of the boiler,where the heat load is low,to further improve the heat transfer safety.A CFB combustion technology was used for coal firing to achieve a uniform heat transfer condition with low heat flux.Pollutant control technologies were adopted to reduce pollutant emissions.Based on the field test,the recommended water standard for the coal-fired CFB drum boilers was determined.With the present technology,the treated recovery wastewater can be reused in steam-injection boilers to generate superheated steam.The engineering applications show that the boiler efficiency is higher than 90%,the blowdown rate is limited within 5.5%,and the superheat of steam can reach up to 30 K.Besides,the heavy oil recovery efficiency is significantly improved.Moreover,the pollutant emissions of SO2,NOV and dust are controlled within the ranges of 20-90 mg/(N·m^(3)),30-90 mg/(N·m^(3))and 2-10 mg/(N·m^(3))respectively.展开更多
基金supported by National Science and Technology Major Project of China(2019-I-0022-0021)Seed fund of Shanxi Research Institute for Clean Energy,Tsinghua Universitythe National Natural Science Foundation of China(51761125011)。
文摘Non-spherical particles exist widely in natural and industrial fluid systems and the motions of nonspherical particles are significantly different from that of spherical particles.In this paper,a simplified model of non-spherical particles considering particle drag correction,lift,and rotation was established.Based on the Eulerian-Lagrangian simulation,the dispersion characteristics of spherical and nonspherical particles with different Stokes numbers in a high-speed turbulent jet were analyzed and compared considering the effect of particle rotation.The results show that,the differences in particle dispersion and radial velocity fluctuation between non-spherical particles and spherical particles in the jet are significant,especially when Stokes number is large.Moreover,the effects of different type of forces on the dispersion of non-spherical particles and spherical particles were compared in detail,which revealed that the change of the Magnus force caused by the increase in the angular velocity of non-spherical particles plays a dominant role in the differences of particle dispersion.
基金supported by the National Natural Science Foundation of China,No.30471836
文摘Non-adherent bone marrow cell-derived mesenchymal stem cells from C57BL/6J mice were sepa- rated and cultured using the ＂pour-off＂ method. Non-adherent bone marrow cell-derived mesen- chymal stem ceils developed colony-forming unit-fibroblasts, and could be expanded by supple- mentation with epidermal growth factor. Immunocytochemistry showed that the non-adherent bone marrow cell-derived mesenchymal stem cells exposed to basic fibroblast growth factor/epidermal growth factor/nerve growth factor expressed the neuron specific markers, neurofilament-200 and NeuN, in vitro. Non-adherent bone marrow cell-derived mesenchymal stem cells from 13-galactosidase transgenic mice were also transplanted into focal ischemic brain （right corpus striatum） of C57BL/6J mice. At 8 weeks, cells positive for LacZ and 13-galactosidase staining were observed in the ischemic tissues, and cells co-labeled with both 13-galactosidase and NeuN were seen by double immunohistochemical staining. These findings suggest that the non-adherent bone marrow cell-derived mesenchymal stem cells could differentiate into neuronal-like cells in vitro and in vivo.
基金Supported by the National Natural Science Foundation of China(NSFC)(21636004)the National Safety Academy Foundation(U1530107)the National Basic Research Program of China(2012CBA01203).
文摘Drop size distribution(DSD) or mean droplet size(d32) and liquid holdup are two key parameters in a liquid–liquid extraction process. Understanding and accurately predicting those parameters are of great importance in the optimal design of extraction columns as well as mixer–settlers. In this paper, the method of built-in endoscopic probe combined with pulse laser was adopted to measure the droplet size in liquid–liquid dispersions with a pump-impeller in a rectangular mixer. The dispersion law of droplets with holdup range 1% to 24% in batch process and larger flow ratio range 1/5 to 5/1 in continuous process was studied. Under the batch operation condition, the DSD abided by log-normal distribution. With the increase of impeller speed or decrease of dispersed phase holdup, the d32 decreased. In addition, a prediction model of d32 of kerosene/deionized system was established as d32/D = 0.13(1 + 5.9φ)We-0.6. Under the continuous operation condition, the general model for droplet size prediction of kerosene/water system was presented as d32/D = C3(1 + C4φ)We-0.6. For the surfactant system and extraction system, the prediction models met a general model as d32/D = bφnWe-0.6.
基金grants from The National Key Research and Development Program of China(Grant No.2017YFA0700403)National Natural Science Foundation of China(Grant Nos.81573013,31822030,and 31771458)National Basic Research Program of China(Grant No.2018YFA0208903).
文摘Objective:Hepatocellular carcinoma(HCC)is a severely lethal cancer that usually originates from chronic liver injury and inflammation.Although progress on diagnosis and treatment is obvious,the cause of HCC remains unclear.In this study,we sought to determine key genes in HCC development.Methods:To identify key regulators during HCC progression,we performed transcriptome sequencing to obtain time series gene expression data from a mouse model with diethylnitrosamine-induced liver tumors and further verified gene expression and function in vitro and in vivo.Results:Among the differentially expressed genes,Cyp2c29 was continuously downregulated during HCC progression.Overexpression of Cyp2c29 suppressed N F-kB activation and proinflammatory cytokine production by increasing the production o f 14,15-epoxyeicosatrienoic acid in vitro.Furthermore,overexpression of Cyp2c29 in vivo protected against liver inflammation in mouse models of liver injury induced by both acetaminophen and CC14.Two human homologs of mouse Cyp2c29,CYP2C8 and CYP2C9,were found to be downregulated in human HCC progression,and their expression was positively correlated with overall survival in patients with HCC(significance:P=0.046 and 0.0097,respectively).Conclusions:Collectively,through systematic analysis and verification,we determined that C yp2c29 is a novel gene involved in liver injury and inflammation,which may be a potential biomarker for HCC prevention and prognosis determination.
基金the supports of the National Natural Science Foundation of China(21991101,21991100)。
文摘Utilization of carbon dioxide(CO_(2)) is of great significance in the development of CO_(2) absorption and the solution of greenhouse gas effect.Highly efficient conversion of CO_(2) into cyclic carbonate with green catalysts is essential for the more sustainable expansion of CO_(2) fixation.Traditional batch reactor is limited by low efficiency, high cost and low security. Meanwhile, continuous flow system showcased a myriad of virtues, including shortening the residence time from hours to seconds, and decreasing reaction temperature, and possessing the nature of easy industrial scale-up. In this paper, a continuous-flow microreaction system was developed to synthesis propylene carbonate(PC) from propylene oxide(PO) and CO_(2) using 1-butyl-3-methylimidazolium bromide([BMIM]Br) as catalyst. By observing the flow patterns inside microreaction system, the effects of reaction temperature, molar fraction of catalyst, operating pressure, residence time, molar ratio of CO_(2)/PO as well as recycling performance of catalyst on the overall performances were comprehensively evaluated into details. Under different reaction conditions,the flow patterns were set to vary between slug flow and annular flow. The results showed that the yield of propylene carbonate(PC) can reach99.7% at 140℃ and 3.0 MPa with the residence time of 166 s, while the recycling performance of the designed system greatly conforms the future trend of green chemistry.
基金financial support from the National Key Technologies R&D Program of China(2018YFF0216002)。
文摘The classification performance of model coal mill classifiers with different bottom incoming flow inlets was experimentally and numerically studied.The flow field adjacent to two neighboring impeller blades was measured using the particle image velocimetry technique.The results showed that the flow field adjacent to two neighboring blades with the swirling inlet was significantly different from that with the non-swirling inlet.With the swirling inlet,there was a vortex located between two neighboring blades,while with the nonswirling inlet,the vortex was attached to the blade tip.The vorticity of the vortex with the non-swirling inlet was much lower than that with the swirling inlet.The classifier with the non-swirling inlet demonstrated a larger cut size than that with the swirling inlet when the impeller was stationary(~0 r·min-1).As the impeller rotational speed increased,the cut size of the cases with non-swirling and swirling inlets both decreased,and the one with the non-swirling inlet decreased more dramatically.The values of the cut size of the two classifiers were close to each other at a high impeller rotational speed(≥120 r·min-1).The overall separation efficiency of the classifier with the non-swirling inlet was lower than that with the swirling inlet,and monotonically increased as the impeller rotational speed increased.With the swirling inlet,the overall separation efficiency first increased with the impeller rotational speed and then decreased when the rotational speed was above 120 r·min-1,and the variation trend of the separation efficiency was more moderate.As the initial particle concentration increased,the cut sizes of both swirling and non-swirling inlet cases decreased first and then barely changed.At a low initial particle concentration(b 0.04 kg·m-3),the classifier with the swirling inlet had a larger cut size than that with the non-swirling inlet.
基金This work was supported by the National Natural Science Foundation of China(61922007,61873013,U1966202).
文摘Signed networks refer to a class of network systems including not only cooperative but also antagonistic interactions among nodes.Due to the existence of antagonistic interactions in signed networks,the agreement of nodes may not be established,instead of which disagreement behaviors generally emerge.This paper reviews several different disagreement behaviors in signed networks under the single-integrator linear dynamics,where two classes of topologies,namely,the static topology and the dynamic topology,are considered.For the static signed networks with the adjacency weights as(time-varying)scalars,we investigate the convergence behaviors and the fluctuation behaviors with respect to fixed topologies and switching topologies,respectively,and give some brief introductions on the disagreement behaviors of general time-varying signed networks.Correspondingly,several classes of behavior analysis approaches are also provided.For the dynamic signed networks with the adjacency weights as transfer functions or linear time-invariant systems,we show the specific descriptions and characteristics of them such that the disagreement behaviors can be obtained by resorting to the derived static signed graphs.Furthermore,we give their applications to the behavior analysis of static signed networks in the presence of high-order dynamics or communication delays.
基金the supports of the National Natural Science Foundation of China(22025801,22108147)Shui Mu Xue Zhe of Tsinghua University(2020SM056)China Postdoctoral Science Foundation(2021M691761)for this work。
文摘Carbon dioxide(CO_(2))utilization and fixation have become one of the most important research areas nowadays due to the increase of global greenhouse effect.Cyclic carbonate,which is widely used in various fields,can be synthesized by fixation of CO_(2) with epoxide in industry.Moreover,the synthesis of cyclic carbonate is a 100%atom economical reaction,which makes it eco-friendly and promising.To enhance the reaction efficiency and safety,a microreaction system was used as the platform for cycloaddition reaction.In this work,tetrabutylammonium bromide(TBAB)was chosen as catalyst,and propylene oxide(PO)as a mode substrate.Interestingly,the addition of water can increase the propylene carbonate(PC)yield and decrease the activation energy considerably,proving water as catalyst promoter for PC synthesis.PC yield and selectivity could reach 91.6%and 99.8%,respectively.The Influence factors and kinetic equation for CO_(2) cycloaddition were obtained as well.
基金supported by the High-end Foreign Experts Recruitment Plan of China(Grant No.G2021165006L),and the 111 Project(Grant No.B13041).
文摘The indoor thermal history of residents in the hot summer and cold winter climate zone in China have undergone a significant change in recent years,which also changes their seasonal thermal adaptations and this has formed feed-back effects to the increasing usage of air conditioning units in this area.To study the seasonal variations of thermal adaptation,the thermal comfort experiments were conducted on two groups of participants.Each groups included 20 participants who had indoor history mainly with natural ventilation(NV group)and air-conditioning(AC group),respectively.The results demonstrated that the thermal sensation vote(TSV)in warm environments did not differ between AC and NV subjects in summer.However,the TSV of AC subjects were much lower than that of NV subjects in the same standard effective temperature and skin temperature in a cold environment in winter.Overall,the participants who spent most of their time in AC space in winter showed a low level of thermal adaptation with a narrower acceptable skin temperature range of 32.6-33.5℃.Thus,this study presents the basic information regarding the seasonal effects on human thermal adaptation due to different long-term indoor thermal histories.
基金supported by the National Natural Science Foundation of China(No.21801012 to G.L.X.).
文摘Supported Pd catalysts show superior activities for olefin productions from alkynes through semi-hydrogenation reactions,but over-hydrogenation into alkanes highly decreases olefin selectivity.Using phenylacetylene semi-hydrogenation as a model reaction,here we explore the optimization approaches toward better Pd catalysts for alkyne semi-hydrogenation through investigating support effect and metal-support interactions.The results show that the states of Pd with supports can be tuned by varying oxide reducibility,loading ratios,and post-treatments.In our system,0.06 wt.%Pd on rutile-TiO_(2) nanorods shows the highest activity owing to the synergistic effects of single-atoms and clusters.Support reducibility can change the filling degrees of Pd 4d orbitals through varying interfacial bonding strengths,which further affect catalytic activity and selectivity.
基金supports provided by the National Natural Science Foundation of China(grant Nos.52106189 and 52174220)are highly appreciatedThe support provided by the Shuangchuang Doctor Project of Jiangsu Province(grant No.202131196)is also appreciated+1 种基金This research was also financially supported by fund from Key Laboratory of Hubei Province for Coal Conversion and New Carbon Materials,Wuhan University of Science and Technology(grant No.WKDM202302)This research was also funded by“Double First Class”Construction Project to Enhance Independent Innovation Ability of China University of Mining&Technology(grant No.2022ZZCX03K06).
文摘Understanding the influencing mechanism of turbulent fluctuation on the ignition characteristics of millimeter coal particles is essential.In this work,to study the effect of turbulent fluctuation on ignition time,millimeter coal particles are subjected to a specific flow field,generated in a furnace with symmetric fans.A one-dimensional model with the new proposed correlation and the Ranz-Marshall(R-M)correlation for Nu(Nusselt number)is established to simulate the coal ignition process.In addition,the effects of fan speed,temperature,particle diameter,particle distance and coal type on the ignition time are investigated.It is found that an increase in fan speed from 0 to 3000 rpm leads to a particle Reynolds number Re_(p)increase from 0 to 22.5,and a turbulent particle Reynolds number Re_(t)*increase from 0 to 71.5.With a consideration of the fluctuation effect,the new correlation of Nu gives a better prediction of ignition time compared to the R-M correlation.Moreover,the ignition time is revealed to decrease with an increasing fan speed and an elevating temperature.While the ignition time shows merely an initial boost with enlarging particle distance,it exhibits a linearity with the term of particle diameter dp1.3-1.7 and Reynolds numbers(Nu*/Nu)-0.6(Nu*is turbulent Nusselt number).Based on this relationship,the difference of predicted ignition time is calculated at different Re_(p)and Re_(t)*.It is shown that at low Re_(p)or high Re_(t)*values,the new correlation should substitute for the R-M correlation.
基金Supported by the National Natural Science Foundation of China(grant no:81971217).
文摘Objective The study aimed to explore the association between the site of interictal epileptic discharges(IEDs)on postoperative electroencephalogram(EEG)and seizure recurrence after antiepileptic drug(AED)withdrawal.The study hypothesizes that the concordance of IED sites with surgical sites indicates incomplete resection of epileptic focus,while non-concordance of IED sites with surgical sites indicates postoperative changes or cortical stimulation.The former has a higher risk of seizure recurrence.Methods We retrospectively analyzed the postoperative EEG pattern of 182 consecutive children who underwent resection surgery.To identify the risk factors for seizure recurrence,we compared the attributes of seizure recurred and seizure-free groups by univariate and multivariate analyses.AED tapering was standardized,involving a 25% reduction in the dose of a single type of AED every 2 weeks,independent of the presurgical AED load.Results We attempted AED withdrawal in 116(63.7%)children.Twenty-eight(24.1%)children experienced seizure recurrence during or after AED withdrawal.A greater number of AEDs used at the time of surgery(p=0.005),incomplete resection(p=0.001),and presence of IED on postoperative EEG(p=0.011)are predictors of seizurerecurrence.Thecompletenessof resectionand seizure recurrence after AED withdrawal were related to the presence of IED on the EEG,but not to the concordance of IED with surgical sites.Conclusion For children with abnormal EEG,the decision to discontinue AED should be made more cautiously,regardless of the relative location of the discharge site and the surgical site.
基金support from the China Ministry of Education,its Humanities and Social Sciences Fund,for the project"A Cognitive Critical Study of Multimodal Discourses of Energy Public Opinion"(grant number:21YJA740055).
文摘The present paper explores how the issue of the current energy crisis in the wake of the Covid-19 and Ukraine war was constructed by political cartoons.Adopting Critical Multimodal Metaphor Scenario Analysis,this paper focuses on the DISEASE metaphor scenario,one of the most recurring scenarios in political cartoons on this topic,and specifically emphasizes how the METHOD OF TREATMENT,one of the structural elements in the scenario,is represented.The analysis reveals that two predominant scenarios cOnstitute the representations of the METHOD OF TREATMENT:NARCOTIC Scenario and MEDICINE scenario.They differ in entailments:one frames fossil energy as detrimental narcotic while the other frames it as therapeutic medicine.By means of the two scenarios,these cartoons convey strong criticism of the major involvers in the energy crisis,namely,the E.U.,Russia,and the U.S.The cartoons make full use of the dynamic interplay of visual and/or verbal metonymy,metaphor,and narrative to elicit associations,assumptions and evaluations in the viewers,helping facilitate understanding and constructing a view of the crisis reality.The present analysis sheds light on the way cartoonists reshape the public point of view in the framing of specific event(s).
基金The work presented in this paper is financially supported by the Fundamental Research Funds for the Central Universities(Grant No.2019CDYGYB026)。
文摘Considering the percentage of dissatisfied due to local thermal sensation(PD LTSV),a vertical air temperature difference(ΔT_(d))threshold of about 3°C was recommended in standards.However,some novel air distribution methods might create large positive(which means the head warmer than the feet,vice versa)or negativeΔT_(d),with no suitable proved criteria to be used.In this study,sixteen subjects were seated in a climatic box placed in a climate chamber to evaluate thermal sensation and percentage of dissatisfied with negative and positiveΔT_(d) in different whole-body thermal conditions.Air temperatures were controlled independently at the upper and lower body parts,with 13 different air temperature sets combined with 22°C,25°C,28°C,and 31°C(i.e.-9°C≤ΔT_(d)≤9°C).Results showed that subjects were more thermally sensitive at the upper body and with positiveΔT_(d) than at the lower body or with negativeΔT_(d).The 80%acceptableΔT_(d) range is about-8 to 7°C in overall neutral(TSV=0),-7°C to 6°C in slightly cool(TSV=-0.5)conditions,which is wider than-3 to 3°C in slightly warm conditions(TSV=+0.5).By considering the factors of both TSV andΔT_(d),a new overall percentage of dissatisfied index(OPD P)was proposed.Case studies show that the new OPD P index is more precise and suitable for the evaluations of different air distributions to predict overall percentage of dissatisfied in thermal environments with vertical air temperature difference.
文摘Some eclogites and the related high-P metamorphic belt have been found for the first time from the Tongbai Mountains, Henan Province, where the eclogites and their probable retrogressive products —— garnet amphibolites —— occur as lenses in mica-schists. The fresheclogites comprise garnet, omphacite, quartz, rutile, phengite, barroisite, etc. The composi-
基金This research was financially supported by the National Key Research and Development Program of China(No.2019YFE0100300-05)the Fundamental Research Funds for the Central Universities(No.2020CDCGJ027)+2 种基金the 111 Project(No.B13041)Academy of Finland(No.329306)The author,Yuxin Wu,would like to thank the Chinese Scholarship Council(No.201806050244)for their sponsorship of a research visiting study aboard at Aalto University in Finland.
文摘Individual thermal comfort models based on physiological parameters could improve the efficiency of the personal thermal comfort control system.However,the effect of thermal history has not been fully addressed in these models.In this study,climate chamber experiments were conducted in winter using 32 subjects who have different indoor and outdoor thermal histories.Two kinds of thermal conditions were investigated:the temperature dropping(24-16℃)and severe cold(12℃)conditions.A simplified method using historical air temperature to quantify the thermal history was proposed and used to predict thermal comfort and thermal demand from physical or physiological parameters.Results show the accuracies of individual thermal sensation prediction was low to about 30%by using the PMV index in cold environments of this study.Base on the sensitivity and reliability of physiological responses,five local skin temperatures(at hand,calf,head,arm and thigh)and the heart rate are optimal input parameters for the individual thermal comfort model.With the proposed historical air temperature as an additional input,the general accuracies using classification tree model C5.0 were increased up by 15.5%for thermal comfort prediction and up by 29.8%for thermal demand prediction.Thus,when predicting thermal demands in winter,the factor of thermal history should be considered.
基金the Key Research and Development Project of Ningxia(2018BDE02057)the National Natural Science Foundation of China(219911100,219911101)for this work.
文摘Global warming and climate change due to anthropogenic carbon dioxide(CO_(2))have aroused significant concerns at the global scale due to rapid economic growth in industries and other fields.Therefore,CO_(2)capture,use,and storage have become particularly important.In this review,general background and methods for CO_(2)capture and separation,in particular,on ionic liquids(ILs)-based solvents and materials,are discussed.Comprehensive surveys of ILs for CO_(2)absorption are presented,which focused mainly on experimental researches,and then the concept is extended to functionalized absorbents and recent developments for CO_(2)capture.Major advantages and disadvantages of amines-based and ILs-based absorbents are discussed in this review.Solutions of traditional amines(MEA,MDEA,DEA,AMP,PZ,etc.)and ILs(conventional ILs,functionalized ILs,etc.)are summarized.Moreover,research progresses on CO_(2)separation are also introduced focusing mainly on amines and ILs-based membranes(e.g.supported amines membranes,SILMs).Futhermore,the fixation of CO_(2)into cyclic carbonates catalyzed by ILs(pure ILs,complex catalyst system with ILs,supported ILs,etc.)is summarized,clearly explaining the mechanism of CO_(2)fixation with ILs.Finally,exploration of some recent studies about CO_(2)capture and conversion by ILs and challenges for further progress are presented and related suggestions are put forward.
基金the National Natural Science Foundation of China(Grant No.51761125011).
文摘In this paper,the design and operation of a novel coal-fired circulating fluidized bed(CFB)drum boiler that can generate superheated steam using saline water were introduced.The natural circulation water dynamics with a drum was adopted instead of the traditional once-through steam generator(OTSG)design,so that superheated steam can be generated for the better performance of the steam assisted gravity drainage(SAGD)technology in heavy oil recovery.The optimized staged evaporation method was proposed to further decrease the salinity of water in the clean water section of the boiler.The evaporating pipes of the salted water section were rearranged in the back pass of the boiler,where the heat load is low,to further improve the heat transfer safety.A CFB combustion technology was used for coal firing to achieve a uniform heat transfer condition with low heat flux.Pollutant control technologies were adopted to reduce pollutant emissions.Based on the field test,the recommended water standard for the coal-fired CFB drum boilers was determined.With the present technology,the treated recovery wastewater can be reused in steam-injection boilers to generate superheated steam.The engineering applications show that the boiler efficiency is higher than 90%,the blowdown rate is limited within 5.5%,and the superheat of steam can reach up to 30 K.Besides,the heavy oil recovery efficiency is significantly improved.Moreover,the pollutant emissions of SO2,NOV and dust are controlled within the ranges of 20-90 mg/(N·m^(3)),30-90 mg/(N·m^(3))and 2-10 mg/(N·m^(3))respectively.
