Copper–carbon(Cu–C)composites have achieved great success in various fields owing to the greatly improved electrical properties compared to pure Cu,for example,a two-order-of-magnitude increase in current-carrying c...Copper–carbon(Cu–C)composites have achieved great success in various fields owing to the greatly improved electrical properties compared to pure Cu,for example,a two-order-of-magnitude increase in current-carrying capacity(ampacity).However,the frequent fuse failure caused by the poor thermal transport at the Cu–C heterointerface is still the main factor affecting the ampacity.In this study,we unconventionally leverage atomic distortion at Cu grain boundaries to alter the local atomic environments,thereby placing a premium on noticeable enhancement of phonon coupling at the Cu–C heterointerface.Without introducing any additional materials,interfacial thermal transport can be regulated solely through rational microstructural design.This new strategy effectively improves the interfacial thermal conductance by three-fold,reaching the state-of-the-art level in van der Waals(vdW)interface regulation.It can be an innovative strategy for interfacial thermal management by turning the detrimental grain boundaries into a beneficial thermal transport accelerator.展开更多
BACKGROUND： Microglia function as the immune surveyors of the brain under normal physiologica conditions. However, microglia become activated in response to brain injuries and immunological OBJECTIVE： To explore the...BACKGROUND： Microglia function as the immune surveyors of the brain under normal physiologica conditions. However, microglia become activated in response to brain injuries and immunological OBJECTIVE： To explore the influence of scorpion venom （SV） heat-resistant protein on frontal cortex and hippocampal microglia cells in a mice model of Parkinson＇s disease. DESIGN, TIME AND SETTING： Randomized, controlled, cellular immunity study. The experiment was performed at the Physiology Department Laboratory in Dalian Medical University between June 2005 and July 2008. MATERIALS： Ninety-six healthy, C57B1/6 mice; 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine （MPTP） from Sigma, USA; SV heat-resistant protein （Experimental Base Institute in Dalian Medical University）. The mice were randomly divided into four groups （n = 24）： normal control, negative control, model, and SV heat-resistant protein. METHODS： Mice in the model and SV heat-resistant protein groups were subcutaneously injected with MPTP （20 mg/kg） to model Parkinson＇s disease, while the normal control and negative control groups were injected with physiological saline in the neck for 8 successive days. In addition, mice in the model and normal control groups were intraperitoneally injected with physiological saline 2 hours following administration, while SV heat-resistant protein and negative control groups were injected SV heat-resistant protein （0.01 mg/kg）. MAIN OUTCOME MEASURES： lmmunoreactivity of microglia cells in MPTP-treated mice. RESULTS： Compared with normal control mice, MPTP-treated mice displayed increased OX-42 expression in the brain. However, in the SV heat-resistant protein-treated mice, OX-42 expression was decreased, compared to the model group. In the model mouse group, the number of OX-42-positive microglia was increased in the frontal cortex, caudatum, and hippocampal hilus, compared to the normal control mice （P 〈 0.01）. However, in the SV heat-resistant protein-treated mice, the number of OX-42-positive microglia significantly decreased in the frontal cortex, caudatum, and hippocampal hilus, compared to the model group （P 〈 0.01）. CONCLUSION： SV heat-resistant protein inhibited MPTP-induced microglial activation in the mouse frontal cortex and hippocampus, resulting in reduced microglial activation in the brain.展开更多
A radiative heat transfer mathematical model for a one-dimensional long furnace was set up in a through-type roller-hearth furnace （TTRHF） in compact strip production （CSP）. To accurately predict the heat exchange...A radiative heat transfer mathematical model for a one-dimensional long furnace was set up in a through-type roller-hearth furnace （TTRHF） in compact strip production （CSP）. To accurately predict the heat exchange in the furnace, modeling of the complex gas energy-balance equation in volume zones was considered, and the heat transfer model of heating slabs and wall lines was coupled with the radiative heat transfer model to identify the surface zonal temperature. With numerical simulation, the temperature fields of gas, slabs, and wall lines in the furnace under one typical working condition were carefully accounted and analyzed. The fundamental theory for analyzing the thermal process in TI＇RI-IF was provided.展开更多
The mechanism of coke size segregation in the radial direction of pre-chamber in coke dry quenching （CDQ） shaft was investigated by experiment and numerical analysis. The experimental apparatus was a cold three-dime...The mechanism of coke size segregation in the radial direction of pre-chamber in coke dry quenching （CDQ） shaft was investigated by experiment and numerical analysis. The experimental apparatus was a cold three-dimensional semicircle model for bell-type charging, which was used to study the influences of different kinds of bells and different stock line levels on the radial distribution of coke size in the radial direction of a pre-chamber. A mathematical model was used, which is capable of estimating the radial average size distribution as well as the radial deposit distribution of each particle size for multiple size coke with a few fixed parameters. The calculated results agree well with the experimental data, which proves the reliability of both experimental study and numerical analysis.展开更多
Objective:To monitor the incidence of BK virus infection in hematuria of renal transplant recipients induced by different immunizations.Methods:A total of 109 patients who underwent renal transplantation in Baogang Ho...Objective:To monitor the incidence of BK virus infection in hematuria of renal transplant recipients induced by different immunizations.Methods:A total of 109 patients who underwent renal transplantation in Baogang Hospital of Inner Mongolia from January 2019 to December 2022 were analyzed retrospectively.The results of BK virus DNA detection in urine and blood were observed after operation.They were divided into three groups according to different immunosuppressive induction regimens;35 patients in group A,42 patients in group B,and 32 patients in group C(basiliximab).To explore the effect of different immune induction regimens on BK virus infection in renal transplant recipients.Results:The positive rate of urine BK virus in all patients in 1 month after operation was 10.09%(11/109),which was significantly higher than that of blood BK virus 0%(0/109),and the difference had a statistical significance(p<.05).The positive rate of urine BK virus in all patients in 6 months after operation was 31.19%(34/109),which was significantly higher than that of blood BK virus 3.67%(4/109),and the difference had a statistical significance(p<.05).The positive rate of urine BK virus in all patients in 12 months after operation was 35.79%(39/109),which was significantly higher than that of blood BK virus 5.50%(6/109),and the difference had a statistical significance(p<.05).The urinary BK virus infection rate was increased significantly from 1 month to 6 months after operation,but was not increased significantly from 6 months to 12 months after operation.There was a statistically significant difference between the two groups(p<.05).The BK virus infection rate in renal transplant recipients induced by basiliximab within the first month was significantly lower than that in patients using polyclonal antibodies,but the urinary BK virus infection rate after one year was not significantly different from that in patients using polyclonal antibodies.Conclusions:There are slight differences in BK virus infection after early renal transplantation with different immune induction therapies,but there is no significant difference in the long-term.It is recommended to strengthen the early monitoring of BK virus after renal transplantation,timely adjust immunosuppressive regimens to achieve the early detection and early treatment.展开更多
An improved discontinuous space vector modulation(IDSVM)approach is proposed through analysis of key factors to impact fault tolerance control performance for the AC/DC converter in an all-DC offshore wind power syste...An improved discontinuous space vector modulation(IDSVM)approach is proposed through analysis of key factors to impact fault tolerance control performance for the AC/DC converter in an all-DC offshore wind power system.The three main factors being studied are compensation ratios of active vectors,type of vectors used to resynthesize reference voltage vector and zero vectors distribution in time domain.Their effects are discussed from perspective of energy input,transmission and loss in the AC/DC converter.Three schemes using different compensation ratios for active vectors are compared,and scheme C using projections on current axis achieves better fault tolerance performance.In this paper,the distorted voltage vector is used to synthesize reference voltage vector and the healthy zero vector is redistributed in the twelve sectors.The former is beneficial to reduce three-phase current spikes and the latter helps to stabilize DC-link voltage.Performances of the improved modulation approach are verified on an experimental platform simulating the offshore wind turbine with single switch and multiple switch open-circuit faults.Its robustness and high performance are thoroughly evaluated.展开更多
The use of porous skeletons for encapsulating phase change materials(PCMs)is an effective approach to addressing issues such as leakage,low thermal conductivity,and poor photothermal conversion efficiency.Inspired by ...The use of porous skeletons for encapsulating phase change materials(PCMs)is an effective approach to addressing issues such as leakage,low thermal conductivity,and poor photothermal conversion efficiency.Inspired by the hollow skeletal structure found in birds in nature,high-quality 3D interconnected hollow diamond foam(HDF)was fabricated using a series of processes,including microwave plasma chemical vapor deposition(CVD),laser perforation,and acid immersion.This HDF was then used as a scaffold to encapsulate PEG2000.The results demonstrate that HDF significantly reduces the supercooling degree and latent heat discrepancy of PEG2000.Compared to pure PEG2000,the thermal conductivity of the HDF/PEG increased by 378%,while its latent heat reached 111.48 J/g,accompanied by a photothermal conversion efficiency of up to 86.68%.The significant performance improvement is mainly attributed to the combination of the excellent properties of the diamond with the inherent advantages of the 3D interconnected structure in HDF,which creates a high-conductivity transport network inside.Moreover,the HDF/PEG composite extends the temperature cycling time of electronic components by 4 times for heating and 2.3 times for cooling,thereby prolonging the operational lifetime of electronic devices.HDF/PEG offers an integrated solution for solar energy collection,photothermal conversion,heat dissipation in electronic components,and thermal energy transfer/storage.This innovative approach provides innovative ideas for the design and fabrication of composite PCMs and has great application potential,such as solar energy utilization,thermal management,and thermal energy storage.展开更多
Integrating phase change materials(PCM)into thermal insulation materials offers a novel approach to aerospace thermal protection.Herein,we used waste biomass as a template;by selecting the appropriate carbonization te...Integrating phase change materials(PCM)into thermal insulation materials offers a novel approach to aerospace thermal protection.Herein,we used waste biomass as a template;by selecting the appropriate carbonization temperature,we obtained carbon aerogels(CCA)with extremely high porosity(95.8%)and high pore volume.After encapsulating PEG2000,we achieved high enthalpy(137.79 J g^(−1),91%of pure PEG2000)and low thermal conductivity(0.137 W(m·K)^(–1),45% of pure PEG2000).Thanks to the rich hierarchical nano-micro porous structure of CCA and the high latent heat of PEG2000,CCA/PEG exhibits excellent thermal insulation properties(under a heating temperature of 131℃,the material takes 1400 s to reach its maximum temperature and can be maintained below 65℃)and cycle performance.Additionally,irradiation destroyed the structure of CCA/PEG,leading to the degradation of PEG and the formation of other carbonyl-containing compounds,which decreased its latent heat(4.2%)and thermal conductivity(16.1%).However,the irradiation-resistant CCA,acting as a protective layer,minimizes the impact of irradiation on PEG2000.Instead,irradiation enhances the hierarchical porous structure of the material,ultimately improving its thermal insulation performance.CCA/PEG has potential application prospects in thermal protection and aerospace and is a strong competitor for high-efficiency thermal insulation materials.展开更多
Owing to its merits in energy savings, environmental protection and coke quality improvement, the Coke Dry Quenching (CDQ) technology is favorite in coke making industry today. In order to validate the mathematical mo...Owing to its merits in energy savings, environmental protection and coke quality improvement, the Coke Dry Quenching (CDQ) technology is favorite in coke making industry today. In order to validate the mathematical model developed for the cooling process of real CDQ shaft, the one-seventh scale experimental setup was established. With the air as the working fluid and the coke as the packed bed, the coke and gas temperatures and the pressure drop in the cooling shaft were measured. A mathematical model based on the non-Darcian and non-thermal equilibrium model for the cooling process of the CDQ experimental shaft was presented. The computational results were compared to the experimental data. It was found that most numerical predictions were supported by the measured values.展开更多
Seawater has obvious resource reserve advantages compared to fresh water,and so the huge potential advantages for large-scale electrolysis of hydrogen production has been paid more attention to;but at the same time,el...Seawater has obvious resource reserve advantages compared to fresh water,and so the huge potential advantages for large-scale electrolysis of hydrogen production has been paid more attention to;but at the same time,electrolysis of seawater requires more stable and active catalysts to deal with seawater corrosion problems.Graphene-based materials are very suitable as composite supports for catalysts due to their high electrical conductivity,specific surface area,and porosity.Therefore,the review introduces the problems faced by seawater electrolysis for hydrogen production and the various catalysts performance.Among them,the advantages of catalysis of graphene-based catalysts and the methods of enhancement the catalytic performance of graphene are emphasized.Finally,the development direction of composite catalysts is prospected,hoping to provide guidance for the preparation of more efficient electrocatalysts for seawater electrolysis.展开更多
When nano-fillers are used to enhance the thermal conductivity of organic phase change materials(PCMs),the naturally formed interface is considered to hinder thermal transport of the composite PCMs.However,the effect ...When nano-fillers are used to enhance the thermal conductivity of organic phase change materials(PCMs),the naturally formed interface is considered to hinder thermal transport of the composite PCMs.However,the effect of the interface on the thermal properties of surrounding PCM has not been fully studied.In this paper,three composite PCMs(Ery@SiC,Ery@SiO_(2) and Ery@Si_(3)N_(4))were prepared by melt-blending method.The local thermal conductivity and reduced Young’s modulus(E^(*))of the erythritol at the interface and far away from the interface in the composite PCMs were simultaneously measured by scanning thermal microscopy(SThM).The results revealed significant enhancement in local thermal conductivity of erythritol at the interface and its obvious positive correlation with E^(*).For different composite PCMs,molecular dynamics(MD)simulations suggested that the increase in intrinsic thermal conductivity and E^(*)of erythritol is attributed to the increase in interaction energy between erythritol and nanoparticles,as more erythritol phonon vibrations transform from localized mode to delocalized mode and erythritol has a higher density at the interface.These findings will provide new ideas for the design of PCM for energy storage.展开更多
Hybrid composites made of metal-organic frameworks(MOFs)and lanthanide-doped upconversion nanoparticles(UCNPs)have attracted considerable interest for their synergistically enhanced functions in various applications s...Hybrid composites made of metal-organic frameworks(MOFs)and lanthanide-doped upconversion nanoparticles(UCNPs)have attracted considerable interest for their synergistically enhanced functions in various applications such as chemical sensing,photocatalysis,anticounterfeiting and nanomedicine.However,precise assembly of MOF/UCNP hybrid composites with tunable morphologies remains a challenge due to the lack of effective synthetic methods and fundamental understanding of the growth mechanisms.Herein,we propose a modulator-directed assembly strategy to synthesize a series of ZIF-8@UCNP composites(ZIF-8=zeolitic imidazolate framework-8).The UCNPs densely paved on the surface of ZIF-8 microcrystals and endowed the composites with intense upconversion blue emission,which were verified by steady-state/transient photoluminescence(PL)spectroscopy and single-particle imaging.Ethylenediamine(EDA)was firstly used as a modulator to fine-tune the predominant MOF facets and realized distinct morphologies of the composites.By adjusting the concentration of EDA from 0 to 25 mmol/L,the morphology of the ZIF-8@UCNP composites was tuned from rhombic dodecahedron(RD)to truncated rhombic dodecahedron(TRD),cube with truncated edges(CTE),cube,and finally a unique form of interpenetration twins(IT).The nucleation and growth process of the ZIF-8@UCNP composites was monitored by time-dependent scanning electron microscopy(SEM)images and the formation mechanism was thoroughly revealed.Furthermore,we demonstrated that the strategy for assembly of morphology-controllable ZIF-8@UCNP composites was generally applicable to various UCNPs with different sizes and shapes.The proposed strategy is expected to open up new avenues for the controllable synthesis of MOF/UCNP composites toward diverse applications.展开更多
In order to obtain a better understanding of flow characteristics of displacement ventilation, the three-dimensional numerical models are developed using the CFD technology. The numerical simulation results are verifi...In order to obtain a better understanding of flow characteristics of displacement ventilation, the three-dimensional numerical models are developed using the CFD technology. The numerical simulation results are verified by experiments, based on this, the velocity and temperature distribution of three-dimensional displacement ventilation system with single and double heat sources are studied. Velocity and temperature fields under two different cases of heat source are analyzed and compared. The numerical results show that there are three layers in vertical temperature fields of displacement ventilation system with single or double heat sources, and the vertical temperature distribution of single heat source is different from that of double heat sources. When indoor load is large, the comfort requirement of people indoor can＇t be satisfied with displacement ventilation system only, thus an additional refrigeration system is necessary. Furthermore, under the condition of two heat sources, the displacement ventilation parameters can＇t be computed simply according to single heat source inlet parameters, therefore the interaction between heat sources should be considered.展开更多
The revelation of thermal energy exchange mechanism of human body is challenging yet worthwhile,because it can clearly explain the changes in human symptoms and health status.Understanding,the heat transfer of the ski...The revelation of thermal energy exchange mechanism of human body is challenging yet worthwhile,because it can clearly explain the changes in human symptoms and health status.Understanding,the heat transfer of the skin is significant because the skin is the foremost organ for the energy exchange between the human body and the environment.In order to diagnose the physiological conditions of human skin without causing any damage,it is necessary to use a non-invasive measurement technique by means of a conformal flexible sensor.The harmonic method can minimize the thermal-induced injury to the skin due to its low heat generating properties.A novel type of computational theory assessing skin thermal conductivity,blood perfusion rate of capillaries in the dermis,and superficial subcutaneous tissues was formed by combining the multi-medium thermal diffusion model and the bio-thermal model(Pennes equation).The skins of the hand back of six healthy subjects were measured.It was found that the results revealed no consistent changes in thermal conductivity were observed across genders and ages.The measured blood perfusion rates were within the range of human capillary flow.It was found that female subjects had a higher perfusion rate range(0.0058-0.0061 s^(-1))than male subjects(0.0032-0.0049 s^(-1)),which is consistent with invasive medical studies about the gender difference in blood flow rates and stimulated effects in relaxation situations.展开更多
This study aimed to investigate the protective effect of nicotine on dopaminergic neurons and its mechanisms in mice with Parkinson disease(PD)induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP).C57BL/6J mic...This study aimed to investigate the protective effect of nicotine on dopaminergic neurons and its mechanisms in mice with Parkinson disease(PD)induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP).C57BL/6J mice were injected with MPTP for 8 days to establish a PD model.Nicotine was given for 10 days in the nicotine therapeutic group.Animals were examined behaviorally with the pole test and traction test.Tyrosine hydroxylase(TH)andγ-aminobutyric acid(GABA)were determined by using the immunocytochem-istry(ICC)method.The ultrastructural changes of the caudate nucleus(CN)were observed under electron microscopy.The results showed that pretreatment with nicotine could improve the dyskinesia of PD mice markedly.Simultaneously,TH-positive(P<0.01)neurons and GABA-positive(P<0.05)neurons in the nicotine therapeutic group were significantly more than those in the model group.The ultrastructural injury of the nicotine therapeutic group was also ameliorated.Nicotine has protective effects on theγ-aminobutyric acid neurons and dopaminergic neurons in the MPTP-treated mice.展开更多
A two-dimensional mathematical model has been undertaken to describe coupled liquid steel’s turbulent flow and heat transfer with solidification in the crystallizer of inverse casting. The solid-liquid phase change p...A two-dimensional mathematical model has been undertaken to describe coupled liquid steel’s turbulent flow and heat transfer with solidification in the crystallizer of inverse casting. The solid-liquid phase change phenomena have been modeled by using the continuum formulations and considering the mush zone as porous media. The turbulence flow has been accounted for, using a modified version of the low-Reynolds-number k -ε turbulence model. A well-known numerical procedure, SIMPLE, has been used to solve the control equations. The effects of some main parameters on the solidification behavior have been studied, such as the casting speed, the thickness and the initial temperature of mother sheet the superheat degree of liquid steel.展开更多
Body core temperature is an important physiological indicator for self-health management and medical diagnosis.However,existing devices always fails to achieve continuous monitoring of core body temperature due to the...Body core temperature is an important physiological indicator for self-health management and medical diagnosis.However,existing devices always fails to achieve continuous monitoring of core body temperature due to their invasive ormotion-restricted measurement principles.Here,a wearable flexible devicewhich can continuouslymonitor the core body temperature was developed.The flexible device integrated with fourteen temperature sensors and one thermal conductivity sensor on the polydimethylsiloxane substrate can be conformally attached to the human skin.With the wearable data processing module and wireless communication module,the continuous monitoring of the core body temperature for 24 h and the portable monitoring of the skin thermal conductivity were realized using this device.Owing to the annular distribution design of the temperature sensor and the directional heat transfer design of the thermal conductivity sensor,this device is comparable in accuracy and stability compared to standard instruments that require invasive or motion-restricted measurements.展开更多
基金financial support from the National Natural Science Foundation of China(Nos.52222602 and 52476052)Fundamental Research Funds for the Central Universities(FRF-TP-22-001C1 and FRF-EYIT-23-05).
文摘Copper–carbon(Cu–C)composites have achieved great success in various fields owing to the greatly improved electrical properties compared to pure Cu,for example,a two-order-of-magnitude increase in current-carrying capacity(ampacity).However,the frequent fuse failure caused by the poor thermal transport at the Cu–C heterointerface is still the main factor affecting the ampacity.In this study,we unconventionally leverage atomic distortion at Cu grain boundaries to alter the local atomic environments,thereby placing a premium on noticeable enhancement of phonon coupling at the Cu–C heterointerface.Without introducing any additional materials,interfacial thermal transport can be regulated solely through rational microstructural design.This new strategy effectively improves the interfacial thermal conductance by three-fold,reaching the state-of-the-art level in van der Waals(vdW)interface regulation.It can be an innovative strategy for interfacial thermal management by turning the detrimental grain boundaries into a beneficial thermal transport accelerator.
基金National Natural Science Foundation of China, No.30770737
文摘BACKGROUND： Microglia function as the immune surveyors of the brain under normal physiologica conditions. However, microglia become activated in response to brain injuries and immunological OBJECTIVE： To explore the influence of scorpion venom （SV） heat-resistant protein on frontal cortex and hippocampal microglia cells in a mice model of Parkinson＇s disease. DESIGN, TIME AND SETTING： Randomized, controlled, cellular immunity study. The experiment was performed at the Physiology Department Laboratory in Dalian Medical University between June 2005 and July 2008. MATERIALS： Ninety-six healthy, C57B1/6 mice; 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine （MPTP） from Sigma, USA; SV heat-resistant protein （Experimental Base Institute in Dalian Medical University）. The mice were randomly divided into four groups （n = 24）： normal control, negative control, model, and SV heat-resistant protein. METHODS： Mice in the model and SV heat-resistant protein groups were subcutaneously injected with MPTP （20 mg/kg） to model Parkinson＇s disease, while the normal control and negative control groups were injected with physiological saline in the neck for 8 successive days. In addition, mice in the model and normal control groups were intraperitoneally injected with physiological saline 2 hours following administration, while SV heat-resistant protein and negative control groups were injected SV heat-resistant protein （0.01 mg/kg）. MAIN OUTCOME MEASURES： lmmunoreactivity of microglia cells in MPTP-treated mice. RESULTS： Compared with normal control mice, MPTP-treated mice displayed increased OX-42 expression in the brain. However, in the SV heat-resistant protein-treated mice, OX-42 expression was decreased, compared to the model group. In the model mouse group, the number of OX-42-positive microglia was increased in the frontal cortex, caudatum, and hippocampal hilus, compared to the normal control mice （P 〈 0.01）. However, in the SV heat-resistant protein-treated mice, the number of OX-42-positive microglia significantly decreased in the frontal cortex, caudatum, and hippocampal hilus, compared to the model group （P 〈 0.01）. CONCLUSION： SV heat-resistant protein inhibited MPTP-induced microglial activation in the mouse frontal cortex and hippocampus, resulting in reduced microglial activation in the brain.
文摘A radiative heat transfer mathematical model for a one-dimensional long furnace was set up in a through-type roller-hearth furnace （TTRHF） in compact strip production （CSP）. To accurately predict the heat exchange in the furnace, modeling of the complex gas energy-balance equation in volume zones was considered, and the heat transfer model of heating slabs and wall lines was coupled with the radiative heat transfer model to identify the surface zonal temperature. With numerical simulation, the temperature fields of gas, slabs, and wall lines in the furnace under one typical working condition were carefully accounted and analyzed. The fundamental theory for analyzing the thermal process in TI＇RI-IF was provided.
文摘The mechanism of coke size segregation in the radial direction of pre-chamber in coke dry quenching （CDQ） shaft was investigated by experiment and numerical analysis. The experimental apparatus was a cold three-dimensional semicircle model for bell-type charging, which was used to study the influences of different kinds of bells and different stock line levels on the radial distribution of coke size in the radial direction of a pre-chamber. A mathematical model was used, which is capable of estimating the radial average size distribution as well as the radial deposit distribution of each particle size for multiple size coke with a few fixed parameters. The calculated results agree well with the experimental data, which proves the reliability of both experimental study and numerical analysis.
基金funded by Baotou Scientific and Technological Program(2020Z1009-7).
文摘Objective:To monitor the incidence of BK virus infection in hematuria of renal transplant recipients induced by different immunizations.Methods:A total of 109 patients who underwent renal transplantation in Baogang Hospital of Inner Mongolia from January 2019 to December 2022 were analyzed retrospectively.The results of BK virus DNA detection in urine and blood were observed after operation.They were divided into three groups according to different immunosuppressive induction regimens;35 patients in group A,42 patients in group B,and 32 patients in group C(basiliximab).To explore the effect of different immune induction regimens on BK virus infection in renal transplant recipients.Results:The positive rate of urine BK virus in all patients in 1 month after operation was 10.09%(11/109),which was significantly higher than that of blood BK virus 0%(0/109),and the difference had a statistical significance(p<.05).The positive rate of urine BK virus in all patients in 6 months after operation was 31.19%(34/109),which was significantly higher than that of blood BK virus 3.67%(4/109),and the difference had a statistical significance(p<.05).The positive rate of urine BK virus in all patients in 12 months after operation was 35.79%(39/109),which was significantly higher than that of blood BK virus 5.50%(6/109),and the difference had a statistical significance(p<.05).The urinary BK virus infection rate was increased significantly from 1 month to 6 months after operation,but was not increased significantly from 6 months to 12 months after operation.There was a statistically significant difference between the two groups(p<.05).The BK virus infection rate in renal transplant recipients induced by basiliximab within the first month was significantly lower than that in patients using polyclonal antibodies,but the urinary BK virus infection rate after one year was not significantly different from that in patients using polyclonal antibodies.Conclusions:There are slight differences in BK virus infection after early renal transplantation with different immune induction therapies,but there is no significant difference in the long-term.It is recommended to strengthen the early monitoring of BK virus after renal transplantation,timely adjust immunosuppressive regimens to achieve the early detection and early treatment.
基金funded by National Key Research&Development Program of China under Grant No.2019YFE0104800,Major Research Plan of the National Natural Science Foundation of China under Grant No.92270101.
文摘An improved discontinuous space vector modulation(IDSVM)approach is proposed through analysis of key factors to impact fault tolerance control performance for the AC/DC converter in an all-DC offshore wind power system.The three main factors being studied are compensation ratios of active vectors,type of vectors used to resynthesize reference voltage vector and zero vectors distribution in time domain.Their effects are discussed from perspective of energy input,transmission and loss in the AC/DC converter.Three schemes using different compensation ratios for active vectors are compared,and scheme C using projections on current axis achieves better fault tolerance performance.In this paper,the distorted voltage vector is used to synthesize reference voltage vector and the healthy zero vector is redistributed in the twelve sectors.The former is beneficial to reduce three-phase current spikes and the latter helps to stabilize DC-link voltage.Performances of the improved modulation approach are verified on an experimental platform simulating the offshore wind turbine with single switch and multiple switch open-circuit faults.Its robustness and high performance are thoroughly evaluated.
基金supported by the National Natural Science Foundation of China(Grant Nos.52176054,52236006,52172037,and 52350362)the Natural Science Foundation of Guangdong Province,China(Grant No.2024A1515012033).
文摘The use of porous skeletons for encapsulating phase change materials(PCMs)is an effective approach to addressing issues such as leakage,low thermal conductivity,and poor photothermal conversion efficiency.Inspired by the hollow skeletal structure found in birds in nature,high-quality 3D interconnected hollow diamond foam(HDF)was fabricated using a series of processes,including microwave plasma chemical vapor deposition(CVD),laser perforation,and acid immersion.This HDF was then used as a scaffold to encapsulate PEG2000.The results demonstrate that HDF significantly reduces the supercooling degree and latent heat discrepancy of PEG2000.Compared to pure PEG2000,the thermal conductivity of the HDF/PEG increased by 378%,while its latent heat reached 111.48 J/g,accompanied by a photothermal conversion efficiency of up to 86.68%.The significant performance improvement is mainly attributed to the combination of the excellent properties of the diamond with the inherent advantages of the 3D interconnected structure in HDF,which creates a high-conductivity transport network inside.Moreover,the HDF/PEG composite extends the temperature cycling time of electronic components by 4 times for heating and 2.3 times for cooling,thereby prolonging the operational lifetime of electronic devices.HDF/PEG offers an integrated solution for solar energy collection,photothermal conversion,heat dissipation in electronic components,and thermal energy transfer/storage.This innovative approach provides innovative ideas for the design and fabrication of composite PCMs and has great application potential,such as solar energy utilization,thermal management,and thermal energy storage.
基金funded by the National Natural Science Foundation of China(No.52236006,No.52176054)the Natural Science Foundation of Guangdong province(2024A1515012033).
文摘Integrating phase change materials(PCM)into thermal insulation materials offers a novel approach to aerospace thermal protection.Herein,we used waste biomass as a template;by selecting the appropriate carbonization temperature,we obtained carbon aerogels(CCA)with extremely high porosity(95.8%)and high pore volume.After encapsulating PEG2000,we achieved high enthalpy(137.79 J g^(−1),91%of pure PEG2000)and low thermal conductivity(0.137 W(m·K)^(–1),45% of pure PEG2000).Thanks to the rich hierarchical nano-micro porous structure of CCA and the high latent heat of PEG2000,CCA/PEG exhibits excellent thermal insulation properties(under a heating temperature of 131℃,the material takes 1400 s to reach its maximum temperature and can be maintained below 65℃)and cycle performance.Additionally,irradiation destroyed the structure of CCA/PEG,leading to the degradation of PEG and the formation of other carbonyl-containing compounds,which decreased its latent heat(4.2%)and thermal conductivity(16.1%).However,the irradiation-resistant CCA,acting as a protective layer,minimizes the impact of irradiation on PEG2000.Instead,irradiation enhances the hierarchical porous structure of the material,ultimately improving its thermal insulation performance.CCA/PEG has potential application prospects in thermal protection and aerospace and is a strong competitor for high-efficiency thermal insulation materials.
基金This work has been supported by Cross-Century Talents Projects of Educational Ministry of China.
文摘Owing to its merits in energy savings, environmental protection and coke quality improvement, the Coke Dry Quenching (CDQ) technology is favorite in coke making industry today. In order to validate the mathematical model developed for the cooling process of real CDQ shaft, the one-seventh scale experimental setup was established. With the air as the working fluid and the coke as the packed bed, the coke and gas temperatures and the pressure drop in the cooling shaft were measured. A mathematical model based on the non-Darcian and non-thermal equilibrium model for the cooling process of the CDQ experimental shaft was presented. The computational results were compared to the experimental data. It was found that most numerical predictions were supported by the measured values.
基金Yunnan Precious Metals Laboratory Science and Technology Project(Grant No.YPML-2023050274)National Natural Science Foundation of China(Grant Nos.52231008,52171078).
文摘Seawater has obvious resource reserve advantages compared to fresh water,and so the huge potential advantages for large-scale electrolysis of hydrogen production has been paid more attention to;but at the same time,electrolysis of seawater requires more stable and active catalysts to deal with seawater corrosion problems.Graphene-based materials are very suitable as composite supports for catalysts due to their high electrical conductivity,specific surface area,and porosity.Therefore,the review introduces the problems faced by seawater electrolysis for hydrogen production and the various catalysts performance.Among them,the advantages of catalysis of graphene-based catalysts and the methods of enhancement the catalytic performance of graphene are emphasized.Finally,the development direction of composite catalysts is prospected,hoping to provide guidance for the preparation of more efficient electrocatalysts for seawater electrolysis.
基金supported by the National Key R&D Program of China(No.2023YFF0612804)the National Natural Science Foundation of China(Nos.52222602,52236006,and 22293043)+3 种基金Beijing Nova Program(No.20220484170)the Fundamental Research Funds for the Central Universities(Nos.FRF-TP-22-001C1 and FRF-EYIT-23-05)Foundation of the Youth Innovation Promotion Association of CAS(No.2020048)IPE Project for Frontier Basic Research(No.QYJC-2023-08).
文摘When nano-fillers are used to enhance the thermal conductivity of organic phase change materials(PCMs),the naturally formed interface is considered to hinder thermal transport of the composite PCMs.However,the effect of the interface on the thermal properties of surrounding PCM has not been fully studied.In this paper,three composite PCMs(Ery@SiC,Ery@SiO_(2) and Ery@Si_(3)N_(4))were prepared by melt-blending method.The local thermal conductivity and reduced Young’s modulus(E^(*))of the erythritol at the interface and far away from the interface in the composite PCMs were simultaneously measured by scanning thermal microscopy(SThM).The results revealed significant enhancement in local thermal conductivity of erythritol at the interface and its obvious positive correlation with E^(*).For different composite PCMs,molecular dynamics(MD)simulations suggested that the increase in intrinsic thermal conductivity and E^(*)of erythritol is attributed to the increase in interaction energy between erythritol and nanoparticles,as more erythritol phonon vibrations transform from localized mode to delocalized mode and erythritol has a higher density at the interface.These findings will provide new ideas for the design of PCM for energy storage.
基金This work was supported by the National Natural Science Foundation of China(NSFC)(Nos.U1805252,22175179,22135008,12174392,21975257,and 12104456)NSF of Fujian Province(Nos.2021I0040,2021L3024)the Chinese Academy of Sciences/State Administration of Foreign Experts Affairs(CAS/SAFEA)International Partnership Program for Creative Research Teams.
文摘Hybrid composites made of metal-organic frameworks(MOFs)and lanthanide-doped upconversion nanoparticles(UCNPs)have attracted considerable interest for their synergistically enhanced functions in various applications such as chemical sensing,photocatalysis,anticounterfeiting and nanomedicine.However,precise assembly of MOF/UCNP hybrid composites with tunable morphologies remains a challenge due to the lack of effective synthetic methods and fundamental understanding of the growth mechanisms.Herein,we propose a modulator-directed assembly strategy to synthesize a series of ZIF-8@UCNP composites(ZIF-8=zeolitic imidazolate framework-8).The UCNPs densely paved on the surface of ZIF-8 microcrystals and endowed the composites with intense upconversion blue emission,which were verified by steady-state/transient photoluminescence(PL)spectroscopy and single-particle imaging.Ethylenediamine(EDA)was firstly used as a modulator to fine-tune the predominant MOF facets and realized distinct morphologies of the composites.By adjusting the concentration of EDA from 0 to 25 mmol/L,the morphology of the ZIF-8@UCNP composites was tuned from rhombic dodecahedron(RD)to truncated rhombic dodecahedron(TRD),cube with truncated edges(CTE),cube,and finally a unique form of interpenetration twins(IT).The nucleation and growth process of the ZIF-8@UCNP composites was monitored by time-dependent scanning electron microscopy(SEM)images and the formation mechanism was thoroughly revealed.Furthermore,we demonstrated that the strategy for assembly of morphology-controllable ZIF-8@UCNP composites was generally applicable to various UCNPs with different sizes and shapes.The proposed strategy is expected to open up new avenues for the controllable synthesis of MOF/UCNP composites toward diverse applications.
文摘In order to obtain a better understanding of flow characteristics of displacement ventilation, the three-dimensional numerical models are developed using the CFD technology. The numerical simulation results are verified by experiments, based on this, the velocity and temperature distribution of three-dimensional displacement ventilation system with single and double heat sources are studied. Velocity and temperature fields under two different cases of heat source are analyzed and compared. The numerical results show that there are three layers in vertical temperature fields of displacement ventilation system with single or double heat sources, and the vertical temperature distribution of single heat source is different from that of double heat sources. When indoor load is large, the comfort requirement of people indoor can＇t be satisfied with displacement ventilation system only, thus an additional refrigeration system is necessary. Furthermore, under the condition of two heat sources, the displacement ventilation parameters can＇t be computed simply according to single heat source inlet parameters, therefore the interaction between heat sources should be considered.
基金support from the National Natural Science Foundation of China(Nos.52222602,52201261)Beijing Nova Program(No.20220484170)+1 种基金Ningbo 3315 Innovative Teams Program(No.2019A-14-C)Fundamental Research Funds for the Central Universities(Nos.FRF-TP-22-001C1,FRF-EYIT-23-05).
文摘The revelation of thermal energy exchange mechanism of human body is challenging yet worthwhile,because it can clearly explain the changes in human symptoms and health status.Understanding,the heat transfer of the skin is significant because the skin is the foremost organ for the energy exchange between the human body and the environment.In order to diagnose the physiological conditions of human skin without causing any damage,it is necessary to use a non-invasive measurement technique by means of a conformal flexible sensor.The harmonic method can minimize the thermal-induced injury to the skin due to its low heat generating properties.A novel type of computational theory assessing skin thermal conductivity,blood perfusion rate of capillaries in the dermis,and superficial subcutaneous tissues was formed by combining the multi-medium thermal diffusion model and the bio-thermal model(Pennes equation).The skins of the hand back of six healthy subjects were measured.It was found that the results revealed no consistent changes in thermal conductivity were observed across genders and ages.The measured blood perfusion rates were within the range of human capillary flow.It was found that female subjects had a higher perfusion rate range(0.0058-0.0061 s^(-1))than male subjects(0.0032-0.0049 s^(-1)),which is consistent with invasive medical studies about the gender difference in blood flow rates and stimulated effects in relaxation situations.
基金supported by the Foundation of Education Department of Liaoning Province,China(No.20060211).
文摘This study aimed to investigate the protective effect of nicotine on dopaminergic neurons and its mechanisms in mice with Parkinson disease(PD)induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP).C57BL/6J mice were injected with MPTP for 8 days to establish a PD model.Nicotine was given for 10 days in the nicotine therapeutic group.Animals were examined behaviorally with the pole test and traction test.Tyrosine hydroxylase(TH)andγ-aminobutyric acid(GABA)were determined by using the immunocytochem-istry(ICC)method.The ultrastructural changes of the caudate nucleus(CN)were observed under electron microscopy.The results showed that pretreatment with nicotine could improve the dyskinesia of PD mice markedly.Simultaneously,TH-positive(P<0.01)neurons and GABA-positive(P<0.05)neurons in the nicotine therapeutic group were significantly more than those in the model group.The ultrastructural injury of the nicotine therapeutic group was also ameliorated.Nicotine has protective effects on theγ-aminobutyric acid neurons and dopaminergic neurons in the MPTP-treated mice.
文摘A two-dimensional mathematical model has been undertaken to describe coupled liquid steel’s turbulent flow and heat transfer with solidification in the crystallizer of inverse casting. The solid-liquid phase change phenomena have been modeled by using the continuum formulations and considering the mush zone as porous media. The turbulence flow has been accounted for, using a modified version of the low-Reynolds-number k -ε turbulence model. A well-known numerical procedure, SIMPLE, has been used to solve the control equations. The effects of some main parameters on the solidification behavior have been studied, such as the casting speed, the thickness and the initial temperature of mother sheet the superheat degree of liquid steel.
基金supported by National Natural Science Foundation of China(No.52222602)Fundamental Research Funds for the Central Universities(FRF-TP-22-001C1 and FRF-EYIT-23-05).
文摘Body core temperature is an important physiological indicator for self-health management and medical diagnosis.However,existing devices always fails to achieve continuous monitoring of core body temperature due to their invasive ormotion-restricted measurement principles.Here,a wearable flexible devicewhich can continuouslymonitor the core body temperature was developed.The flexible device integrated with fourteen temperature sensors and one thermal conductivity sensor on the polydimethylsiloxane substrate can be conformally attached to the human skin.With the wearable data processing module and wireless communication module,the continuous monitoring of the core body temperature for 24 h and the portable monitoring of the skin thermal conductivity were realized using this device.Owing to the annular distribution design of the temperature sensor and the directional heat transfer design of the thermal conductivity sensor,this device is comparable in accuracy and stability compared to standard instruments that require invasive or motion-restricted measurements.
