Alkaline water electrolysis(AWE)is the most mature technology for hydrogen production by water electrolysis.Alkaline water electrolyzer consists of multiple electrolysis cells,and a single cell consists of a diaphragm...Alkaline water electrolysis(AWE)is the most mature technology for hydrogen production by water electrolysis.Alkaline water electrolyzer consists of multiple electrolysis cells,and a single cell consists of a diaphragm,electrodes,bipolar plates and end plates,etc.The existing industrial bipolar plate channel is concave-convex structure,which is manufactured by complicated and high-cost mold punching.This structure still results in uneven electrolyte flow and low current density in the electrolytic cell,further increasing in energy consumption and cost of AWE.Thereby,in this article,the electrochemical and flow model is firstly constructed,based on the existing industrial concave and convex flow channel structure of bipolar plate,to study the current density,electrolyte flow and bubble distribution in the electrolysis cell.The reliability of the model was verified by comparison with experimental data in literature.Among which,the electrochemical current density affects the bubble yield,on the other hand,the generated bubbles cover the electrode surface,affecting the active specific surface area and ohmic resistance,which in turn affects the electrochemical reaction.The result indicates that the flow velocity near the bottom of the concave ball approaches zero,while the flow velocity on the convex ball surface is significantly higher.Additionally,vortices are observed within the flow channel structure,leading to an uneven distribution of electrolyte.Next,modelling is used to optimize the bipolar plate structure of AWE by simulating the electrochemistry and fluid flow performances of four kinds of structures,namely,concave and convex,rhombus,wedge and expanded mesh,in the bipolar plate of alkaline water electrolyzer.The results show that the expanded mesh channel structure has the largest current density of 3330 A/m^(2)and electrolyte flow velocity of 0.507 m/s in the electrolytic cell.Under the same current density,the electrolytic cell with the expanded mesh runner structure has the smallest potential and energy consumption.This work provides a useful guide for the comprehensive understanding and optimization of channel structures,and a theoretical basis for the design of large-scale electrolyzer.展开更多
A binary eutectic mixture composed of tetradecanol(TD)and myristic acid(MA)was maximally absorbed into the microstructures of expanded perlite(EP)and expanded vermiculite(EVMT),respectively,through a self-made vacuum ...A binary eutectic mixture composed of tetradecanol(TD)and myristic acid(MA)was maximally absorbed into the microstructures of expanded perlite(EP)and expanded vermiculite(EVMT),respectively,through a self-made vacuum adsorption roller to prepare phase change material(PCM)particle(PCP).Then EP and EVMT-based composite PCM plates were respectively fabricated through a mold pressing method.The thermal property,chemical stability,microstructure and durability were characterized by differential scanning calorimeter(DSC),Fourier transform infrared spectroscope(FT-IR),scanning electron microscope(SEM)and thermal cycling tests,respectively.The results show that both PCPs have high latent heats with 110 J/g for EP-based PCP and more than 130 J/g for EVMT-based PCP,compact microstructure without PCM leakage,stable chemical property and good durability.The research results have proved the feasibility for the vacuum adsorption roller used in the composite PCM fabrication.Results of thermal storage performance experiment indicate that the fabricated PCM plates have better thermal inertia than common building materials,and the thermal storage performance of PCM plates has nonlinearly changed with outside air velocity and temperature increase.Therefore,PCM plates show a significant potential for the practical application of building thermal storage.展开更多
Phase change material(PCM)can reduce the indoor temperature fluctuation and humidity control material can adjust relative humidity used in buildings.In this study,a kind of composite phase change material particles(CP...Phase change material(PCM)can reduce the indoor temperature fluctuation and humidity control material can adjust relative humidity used in buildings.In this study,a kind of composite phase change material particles(CPCMPs)were prepared by vacuum impregnation method with expanded perlite(EP)as supporting material and paraffin as phase change material.Thus,a PCM plate was fabricated by mould pressing method with CPCMPs and then composite phase change humidity control wallboard(CPCHCW)was prepared by spraying the diatom mud on the surface of PCM plate.The composition,thermophysical properties and microstructure were characterized using X-ray diffraction instrument(XRD),differential scanning calorimeter(DSC)and scanning electron microscope(SEM).Additionally,the hygrothermal performance of CPCHCW was characterized by temperature and humidity collaborative test.The results can be summarized as follows:(1)CPCMPs have suitable phase change parameters with melting/freezing point of 18.23°C/29.42°C and higher latent heat of 54.66 J/g/55.63 J/g;(2)the diatom mud can control the humidity of confined space with a certain volume;(3)the combination of diatom mud and PCM plate in CPCHCW can effectively adjust the indoor temperature and humidity.The above conclusions indicate the potential of CPCHCW in the application of building energy efficiency.展开更多
Deformation characteristics of light weight soil with different EPS (expanded polystyrene) sizes were investigated by consolidation tests.The results show that the confined stress-strain relation curve is in S shape,w...Deformation characteristics of light weight soil with different EPS (expanded polystyrene) sizes were investigated by consolidation tests.The results show that the confined stress-strain relation curve is in S shape,which has a good homologous relation with e-p curve and e-lgp curve,and three types of curves reflect obvious structural characteristics of light weight soil.When cement mixed ratio and EPS volume ratio are the same for different specimens,structural strength decreases with the increase of EPS size,but compressibility indexes basically keep unchanged within the structural strength.The settlement of light weight soil can be divided into instantaneous settlement and primary consolidation settlement.It has no obvious rheology property,and 90% of total consolidation deformation can be finished in 1 min.Settlement-time relation of light weight soil can be predicted by the hyperbolic model.S-lgt curve of light weight soil is not in anti-S shape.It is proved that there is no secondary consolidation section,so consolidation coefficient cannot be obtained by time logarithm method.Structural strength and unit price decrease with the increase of EPS size,but the reducing rate of the structural strength is lower than that of the unit price,so the cost of mixed soil can be reduced by increasing the EPS size.The EPS beads with 3-5 mm in diameter are suggested to be used in the construction process,and the prescription of mixed soil can be optimized.展开更多
Through direct shear and triaxial compression tests, effects of expanded polystyrene (EPS) mass ratios in sand-EPS mixtures and stress status on materials' shear behavior were investigated. Hyperbolic curves were ...Through direct shear and triaxial compression tests, effects of expanded polystyrene (EPS) mass ratios in sand-EPS mixtures and stress status on materials' shear behavior were investigated. Hyperbolic curves were used to fit relationship between shear stress and shear displacement. The shear behavior is marginally associated with the EPS ratios and normal/confining stresses. Increases of EPS ratios and decreases of normal/confining stresses result in shear strength decreases. The shapes of Mohr-Coulomb's envelope include linear and piecewise linear types, which are basically determined by the EPS ratio. Such difference is thought related to the embedding or apparent cohesion effect under relatively high EPS ratio conditions. Shear strength parameters can be used for further modeling and design purposes.展开更多
Expanded bed adsorption (EBA) has been introduced as a primary recovery step for protein purification from a whole fermentation broth or unclarified cell homogenates. It can also be integrated with a fermentation or c...Expanded bed adsorption (EBA) has been introduced as a primary recovery step for protein purification from a whole fermentation broth or unclarified cell homogenates. It can also be integrated with a fermentation or cell disruption process. Solid matrix is the principal pillar supporting the successful application of the EBA technology. This article summarizes the solid matrices employed in and developed for the EBA process to date. Further development of solid matrices for the expanded bed technique in the recovery of various biological substances from different sources has been addressed.展开更多
By using hydrothermal synthesis method, successively adding tetrabutyl titanate and expandable flake graphite in 40 mL 0.95% NH4Cl solution prepared the nano TiO2/expandable flake graphite, which was then settled in m...By using hydrothermal synthesis method, successively adding tetrabutyl titanate and expandable flake graphite in 40 mL 0.95% NH4Cl solution prepared the nano TiO2/expandable flake graphite, which was then settled in muffle furnace in the expansion of 10 s under 800 ℃ and got nanosized TiO2/expanded graphite. Synthesized that with CoFe2O4 by chemical coprecipitation method finally prepared magnetic nanosized photocatalyst TiO2/expanded graphite. Magnetic nanosized TiO2/expanded graphite was studied on the photodegradation performance of methyl orange solution and the magnetic recovery after the degradation of methyl orange solution. The experiment result showed that in 50 mL 25 mg/L methyl orange solution joined 120 mg loading 50% TiO2 of the expanded graphite, exposed to ultraviolet irradiation for 1 h, the methyl orange decolorization ratio was 90%. When the load of CoFe2O4 in nanosized TiO2/expanded graphite reached 40%, its magnetic recovery efficiency reached 94.3%.展开更多
The expanded graphite (EG) with a low density and better extinction performance can be used in military as passive jamming material in IR and MMW bands. Its complex refractive index is a significant parameter for the ...The expanded graphite (EG) with a low density and better extinction performance can be used in military as passive jamming material in IR and MMW bands. Its complex refractive index is a significant parameter for the extinction property. This paper presents a method to calculate the complex refractive index of EG. The reflection spectra of EG pellets were measured in the 0.24-2.6μm and 2.5-25μm bands, respectively. Based on the measurement results, the complex refractive index of EG in 5-10μm band was calculated by using Kramers-Kronig(K-K) relation and Bruggeman effective medium theory, and then the errors were analyzed. The results indicate that it is feasible to calculate the complex refractive index of EG based on its IR reflection spectra data.展开更多
For every integer 4≤d≤11,an explicit construction of infinite families of 2d-regular unique-neighbor expanders is presented,which is a generalization of the 6-regular unique-neighbors initially developed by Alon and...For every integer 4≤d≤11,an explicit construction of infinite families of 2d-regular unique-neighbor expanders is presented,which is a generalization of the 6-regular unique-neighbors initially developed by Alon and Capalbo.Additionally,for values of d greater than 11,a sufficient condition is established for employing the same construction method.Our construction method involves the“line product”of large bipartite Ramanujan graphs and a sufficiently good unique-neighbor expander(a small gadget).展开更多
This study is to determine the support mechanism of pre-stressed expandable props for the stope roof in room- and-pillar mining, which is crucial for maintaining stability and preventing roof collapse in mines. Utiliz...This study is to determine the support mechanism of pre-stressed expandable props for the stope roof in room- and-pillar mining, which is crucial for maintaining stability and preventing roof collapse in mines. Utilizing an engineering case from a gold mine in Dandong, China, a laboratory-based similar test is conducted to extract the actual roof characteristic curve. This test continues until the mining stope collapses due to a U-shaped failure. Concurrently, a semi-theoretical method for obtaining the roof characteristic curve is proposed and verified against the actual curve. The semi-theoretical method calculated that the support force and vertical displacement at the demarcation point between the elastic and plastic zones of the roof characteristic curve are 5.0 MPa and 8.20 mm, respectively, corroborating well with the laboratory-based similar test results of 0.22 MPa and 0.730 mm. The weakening factor for the plastic zone in the roof characteristic curve was semi-theoretically estimated to be 0.75. The intersection between the actual roof characteristic curve and the support characteristic curves of expandable props, natural pillars, and concrete props indicates that the expandable prop is the most effective “yielding support” for the stope roof in room-and-pillar mining. That is, the deformation and failure of the stope roof can be effectively controlled with proper release of roof stress. This study provides practical insights for optimizing support strategies in room-and-pillar mining, enhancing the safety and efficiency of mining operations.展开更多
Mechanobiology is a rapidly growing field that has expanded significantly over the past 40 years.There have been great examples of mechanobiology research on the cardiovascular,musculoskeletal,and respiratory systems....Mechanobiology is a rapidly growing field that has expanded significantly over the past 40 years.There have been great examples of mechanobiology research on the cardiovascular,musculoskeletal,and respiratory systems.The field has evolved from the system level to the organ and tissue levels,and down to the cellular and molecular levels,benefiting from scientific progress and technological developments in molecular and cell biology,biomaterials,imaging techniques,and computational tools.Additionally,the interdisciplinary integration of mechanobiology with cell engineering,tissue engineering,and drug delivery has led to promising mechanomedicine applications in both therapeutics and diagnostics.Here,I will discuss two examples at the molecular and cellular levels:(1)mechanical regulation of epigenomics for cell reprogramming,and(2)engineering the mechanical properties of artificial antigen-presenting cells(APCs)for immune cell modulation and cancer therapy.Cell memory of its identity is determined by the epigenetic state of the cells.However,how cells control the epigenetic state and thus cell fate is not well understood,and how mechanical factors such as surface topography,cell morphology,mechanical properties of the extracellular matrix(ECM),and the mechanical deformation of cells regulate the epigenetic state is not clear.In an early study,we showed that biophysical cues,in the form of parallel microgrooves on the surface of cell-adhesive substrates,can replace the effects of small-molecule epigenetic modifiers and significantly improve reprogramming efficiency from fibroblasts to induced pluripotent stem cells.The mechanism relies on the mechanomodulation of the cells’epigenetic state through the activity of histone deacetylase and H3 methyltransferase.We also showed that microtopography promotes a mesenchymal-to-epithelial transition in adult fibroblasts.Nanofibrous scaffolds with aligned fiber orientation produce effects similar to those produced by microgrooves,suggesting that changes in cell morphology may be responsible for the modulation of the epigenetic state.The effects of micro/nanopatterned surfaces may be related to the reduction of intracellular tension and cell adhesion.Indeed,the reduction of actin cytoskeletal tension or cell adhesion at the early phase of reprogramming suppresses the expression of mesenchymal genes,promotes a more open chromatin structure,and significantly enhances the efficiency of induced neuronal(i N)conversion.Specifically,the reduction of intracellular tension or cell adhesion not only modulates global epigenetic marks but also decreases DNA methylation and heterochromatin marks while increasing euchromatin marks at the promoter of neuronal genes,thus enhancing the accessibility for gene activation.Finally,micro-and nano-topographic surfaces that reduce cell adhesion enhance i N reprogramming.These novel findings suggest that the actin cytoskeleton and focal adhesions play an important role in epigenetic regulation for cell fate determination,which may lead to biomaterialbased approaches for more effective cell reprogramming.In addition,matrix stiffness also regulates cell reprogramming,which acts as a biphasic regulator of the epigenetic state and fibroblast-to-neuron conversion efficiency,maximized at an intermediate stiffness of 20 k Pa.ATAC sequencing analysis shows the same trend of chromatin accessibility to neuronal genes at these stiffness levels.Concurrently,we observe peak levels of histone acetylation and histone acetyltransferase(HAT)activity in the nucleus on 20 k Pa matrices,and inhibiting HAT activity abolishes matrix stiffness effects.G-actin and cofilin,the co-transporters shuttling HAT into the nucleus,rise with decreasing matrix stiffness;however,reduced importin-9 on soft matrices limits nuclear transport.These two factors result in a biphasic regulation of HAT transport into the nucleus,which is directly demonstrated on matrices with dynamically tunable stiffness.Furthermore,we find that the regulation of the epigenetic state by the viscoelastic matrix is more pronounced on softermatrices.Cells on viscoelastic matrices exhibit larger nuclei,increased nuclear lamina ruffling,loosely organized chromatin,and faster chromatin dynamics compared to those on elastic matrices.These changes are accompanied by a global increase in euchromatic marks and a local increase in chromatin accessibility at the cis-regulatory elements associated with neuronal and pluripotent genes.Consequently,viscoelastic matrices enhance the efficiency of reprogramming fibroblasts into neurons and induced pluripotent stem cells,respectively.Together,our findings demonstrate the key roles of matrix viscoelasticity in regulating the epigenetic state and uncover a new mechanism of biophysical regulation of chromatin and cell reprogramming,with implications for designing smart materials to engineer cell fate.The viscoelasticity of biomaterials not only regulates cell adhesion and the epigenetic state but also modulates other ligand-receptor interactions such as T cell receptor activation.We developed a scalable microfluidic platform to fabricate synthetic viscoelastic activating cells(Syn VACs)with programmable mechanical and chemical properties.We demonstrated that the viscoelastic nature of Syn VACs significantly impacts T cell functionality.Compared to rigid or elastic microspheres,Syn VACs greatly enhance human T cell expansion with drastic CD8+T cell generation while suppressing regulatory T cell formation,resulting in enhanced tumor-killing capability.Notably,expanding chimeric antigen receptor(CAR)-T cells with Syn VACs achieves approximately 90%CAR transduction efficiency and leads to a six-fold increase in T memory stem cells.These engineered CAR-T cells exhibit superior efficacy in eliminating tumor cells,not only in a human lymphoma mouse model but also in a solid tumor xenograft mouse model of ovarian cancer.Additionally,Syn VAC-expanded CAR-T cells persist for longer periods in vivo to suppress tumor growth and recurrence.These findings underscore the crucial role of mechanical signals in T cell engineering and highlight the potential of the Syn VAC platform in CAR-T therapy and broad immunoengineering applications.These examples of mechanical regulation of cells not only unravel the underlying mechanisms of mechanotransduction in various cells,but also have tremendous potential to translate into therapeutic applications.展开更多
It has been 53 years since the first volume of Acta Veterinaria et Zootechnica Sinica(Chinese Journal of Animal and Veterinary Sciences,CJAVS)was published.The Journal has earned its reputation by presenting high-leve...It has been 53 years since the first volume of Acta Veterinaria et Zootechnica Sinica(Chinese Journal of Animal and Veterinary Sciences,CJAVS)was published.The Journal has earned its reputation by presenting high-level academic and instructive papers,technical reports,and achievements in Chinese,but its influence is still limited to its primary audience,in China.In recent years,international trade of animals and their products have expanded,展开更多
基金financially supported by the National Natural Science Foundation of China(No.52074130)the Engineering Research Center of Resource Utilization of Carbon-containing Waste with Carbon Neutrality,Ministry of Education。
文摘Alkaline water electrolysis(AWE)is the most mature technology for hydrogen production by water electrolysis.Alkaline water electrolyzer consists of multiple electrolysis cells,and a single cell consists of a diaphragm,electrodes,bipolar plates and end plates,etc.The existing industrial bipolar plate channel is concave-convex structure,which is manufactured by complicated and high-cost mold punching.This structure still results in uneven electrolyte flow and low current density in the electrolytic cell,further increasing in energy consumption and cost of AWE.Thereby,in this article,the electrochemical and flow model is firstly constructed,based on the existing industrial concave and convex flow channel structure of bipolar plate,to study the current density,electrolyte flow and bubble distribution in the electrolysis cell.The reliability of the model was verified by comparison with experimental data in literature.Among which,the electrochemical current density affects the bubble yield,on the other hand,the generated bubbles cover the electrode surface,affecting the active specific surface area and ohmic resistance,which in turn affects the electrochemical reaction.The result indicates that the flow velocity near the bottom of the concave ball approaches zero,while the flow velocity on the convex ball surface is significantly higher.Additionally,vortices are observed within the flow channel structure,leading to an uneven distribution of electrolyte.Next,modelling is used to optimize the bipolar plate structure of AWE by simulating the electrochemistry and fluid flow performances of four kinds of structures,namely,concave and convex,rhombus,wedge and expanded mesh,in the bipolar plate of alkaline water electrolyzer.The results show that the expanded mesh channel structure has the largest current density of 3330 A/m^(2)and electrolyte flow velocity of 0.507 m/s in the electrolytic cell.Under the same current density,the electrolytic cell with the expanded mesh runner structure has the smallest potential and energy consumption.This work provides a useful guide for the comprehensive understanding and optimization of channel structures,and a theoretical basis for the design of large-scale electrolyzer.
基金Project(51408184)supported by the National Natural Science Foundation of ChinaProject(E2017202136)supported by the Natural Science Foundation of Hebei Province,China+1 种基金Project(BSBE2017-05)supported by Opening Funds of State Key Laboratory of Building Safety and Built Environment and National Engineering Research Center of Building Technology,ChinaProject(QG2018-3)supported by Hebei Provincial Department of Transportation,China
文摘A binary eutectic mixture composed of tetradecanol(TD)and myristic acid(MA)was maximally absorbed into the microstructures of expanded perlite(EP)and expanded vermiculite(EVMT),respectively,through a self-made vacuum adsorption roller to prepare phase change material(PCM)particle(PCP).Then EP and EVMT-based composite PCM plates were respectively fabricated through a mold pressing method.The thermal property,chemical stability,microstructure and durability were characterized by differential scanning calorimeter(DSC),Fourier transform infrared spectroscope(FT-IR),scanning electron microscope(SEM)and thermal cycling tests,respectively.The results show that both PCPs have high latent heats with 110 J/g for EP-based PCP and more than 130 J/g for EVMT-based PCP,compact microstructure without PCM leakage,stable chemical property and good durability.The research results have proved the feasibility for the vacuum adsorption roller used in the composite PCM fabrication.Results of thermal storage performance experiment indicate that the fabricated PCM plates have better thermal inertia than common building materials,and the thermal storage performance of PCM plates has nonlinearly changed with outside air velocity and temperature increase.Therefore,PCM plates show a significant potential for the practical application of building thermal storage.
基金Project(51408184)supported by the National Natural Science Foundation of ChinaProject(E2017202136)supported by the Natural Science Foundation of Hebei Province,China+1 种基金Project(BSBE2017-05)supported by the Opening Funds of State Key Laboratory of Building Safety and Built Environment and National Engineering Research Center of Building Technology,ChinaProject(QG2018-3)supported by Hebei Provincial Department of Transportation,China
文摘Phase change material(PCM)can reduce the indoor temperature fluctuation and humidity control material can adjust relative humidity used in buildings.In this study,a kind of composite phase change material particles(CPCMPs)were prepared by vacuum impregnation method with expanded perlite(EP)as supporting material and paraffin as phase change material.Thus,a PCM plate was fabricated by mould pressing method with CPCMPs and then composite phase change humidity control wallboard(CPCHCW)was prepared by spraying the diatom mud on the surface of PCM plate.The composition,thermophysical properties and microstructure were characterized using X-ray diffraction instrument(XRD),differential scanning calorimeter(DSC)and scanning electron microscope(SEM).Additionally,the hygrothermal performance of CPCHCW was characterized by temperature and humidity collaborative test.The results can be summarized as follows:(1)CPCMPs have suitable phase change parameters with melting/freezing point of 18.23°C/29.42°C and higher latent heat of 54.66 J/g/55.63 J/g;(2)the diatom mud can control the humidity of confined space with a certain volume;(3)the combination of diatom mud and PCM plate in CPCHCW can effectively adjust the indoor temperature and humidity.The above conclusions indicate the potential of CPCHCW in the application of building energy efficiency.
基金Project(2012JQ7013)supported by the Natural Science Foundation of Shaanxi Province,ChinaProject(QN2012025)supported by the Fundamental Research Funds for the Central Universities of ChinaProject(2011BSJJ084)supported by Research Foundation of Northwest A&F University,China
文摘Deformation characteristics of light weight soil with different EPS (expanded polystyrene) sizes were investigated by consolidation tests.The results show that the confined stress-strain relation curve is in S shape,which has a good homologous relation with e-p curve and e-lgp curve,and three types of curves reflect obvious structural characteristics of light weight soil.When cement mixed ratio and EPS volume ratio are the same for different specimens,structural strength decreases with the increase of EPS size,but compressibility indexes basically keep unchanged within the structural strength.The settlement of light weight soil can be divided into instantaneous settlement and primary consolidation settlement.It has no obvious rheology property,and 90% of total consolidation deformation can be finished in 1 min.Settlement-time relation of light weight soil can be predicted by the hyperbolic model.S-lgt curve of light weight soil is not in anti-S shape.It is proved that there is no secondary consolidation section,so consolidation coefficient cannot be obtained by time logarithm method.Structural strength and unit price decrease with the increase of EPS size,but the reducing rate of the structural strength is lower than that of the unit price,so the cost of mixed soil can be reduced by increasing the EPS size.The EPS beads with 3-5 mm in diameter are suggested to be used in the construction process,and the prescription of mixed soil can be optimized.
基金Project(50708031) supported by the National Natural Science Foundation of ChinaProject supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, SEM
文摘Through direct shear and triaxial compression tests, effects of expanded polystyrene (EPS) mass ratios in sand-EPS mixtures and stress status on materials' shear behavior were investigated. Hyperbolic curves were used to fit relationship between shear stress and shear displacement. The shear behavior is marginally associated with the EPS ratios and normal/confining stresses. Increases of EPS ratios and decreases of normal/confining stresses result in shear strength decreases. The shapes of Mohr-Coulomb's envelope include linear and piecewise linear types, which are basically determined by the EPS ratio. Such difference is thought related to the embedding or apparent cohesion effect under relatively high EPS ratio conditions. Shear strength parameters can be used for further modeling and design purposes.
文摘Expanded bed adsorption (EBA) has been introduced as a primary recovery step for protein purification from a whole fermentation broth or unclarified cell homogenates. It can also be integrated with a fermentation or cell disruption process. Solid matrix is the principal pillar supporting the successful application of the EBA technology. This article summarizes the solid matrices employed in and developed for the EBA process to date. Further development of solid matrices for the expanded bed technique in the recovery of various biological substances from different sources has been addressed.
文摘By using hydrothermal synthesis method, successively adding tetrabutyl titanate and expandable flake graphite in 40 mL 0.95% NH4Cl solution prepared the nano TiO2/expandable flake graphite, which was then settled in muffle furnace in the expansion of 10 s under 800 ℃ and got nanosized TiO2/expanded graphite. Synthesized that with CoFe2O4 by chemical coprecipitation method finally prepared magnetic nanosized photocatalyst TiO2/expanded graphite. Magnetic nanosized TiO2/expanded graphite was studied on the photodegradation performance of methyl orange solution and the magnetic recovery after the degradation of methyl orange solution. The experiment result showed that in 50 mL 25 mg/L methyl orange solution joined 120 mg loading 50% TiO2 of the expanded graphite, exposed to ultraviolet irradiation for 1 h, the methyl orange decolorization ratio was 90%. When the load of CoFe2O4 in nanosized TiO2/expanded graphite reached 40%, its magnetic recovery efficiency reached 94.3%.
文摘The expanded graphite (EG) with a low density and better extinction performance can be used in military as passive jamming material in IR and MMW bands. Its complex refractive index is a significant parameter for the extinction property. This paper presents a method to calculate the complex refractive index of EG. The reflection spectra of EG pellets were measured in the 0.24-2.6μm and 2.5-25μm bands, respectively. Based on the measurement results, the complex refractive index of EG in 5-10μm band was calculated by using Kramers-Kronig(K-K) relation and Bruggeman effective medium theory, and then the errors were analyzed. The results indicate that it is feasible to calculate the complex refractive index of EG based on its IR reflection spectra data.
文摘For every integer 4≤d≤11,an explicit construction of infinite families of 2d-regular unique-neighbor expanders is presented,which is a generalization of the 6-regular unique-neighbors initially developed by Alon and Capalbo.Additionally,for values of d greater than 11,a sufficient condition is established for employing the same construction method.Our construction method involves the“line product”of large bipartite Ramanujan graphs and a sufficiently good unique-neighbor expander(a small gadget).
基金Project(2022YFC2903801) supported by the National Key Research and Development Program of ChinaProjects(52374117, 52274115) supported by the National Natural Science Foundation of China。
文摘This study is to determine the support mechanism of pre-stressed expandable props for the stope roof in room- and-pillar mining, which is crucial for maintaining stability and preventing roof collapse in mines. Utilizing an engineering case from a gold mine in Dandong, China, a laboratory-based similar test is conducted to extract the actual roof characteristic curve. This test continues until the mining stope collapses due to a U-shaped failure. Concurrently, a semi-theoretical method for obtaining the roof characteristic curve is proposed and verified against the actual curve. The semi-theoretical method calculated that the support force and vertical displacement at the demarcation point between the elastic and plastic zones of the roof characteristic curve are 5.0 MPa and 8.20 mm, respectively, corroborating well with the laboratory-based similar test results of 0.22 MPa and 0.730 mm. The weakening factor for the plastic zone in the roof characteristic curve was semi-theoretically estimated to be 0.75. The intersection between the actual roof characteristic curve and the support characteristic curves of expandable props, natural pillars, and concrete props indicates that the expandable prop is the most effective “yielding support” for the stope roof in room-and-pillar mining. That is, the deformation and failure of the stope roof can be effectively controlled with proper release of roof stress. This study provides practical insights for optimizing support strategies in room-and-pillar mining, enhancing the safety and efficiency of mining operations.
文摘Mechanobiology is a rapidly growing field that has expanded significantly over the past 40 years.There have been great examples of mechanobiology research on the cardiovascular,musculoskeletal,and respiratory systems.The field has evolved from the system level to the organ and tissue levels,and down to the cellular and molecular levels,benefiting from scientific progress and technological developments in molecular and cell biology,biomaterials,imaging techniques,and computational tools.Additionally,the interdisciplinary integration of mechanobiology with cell engineering,tissue engineering,and drug delivery has led to promising mechanomedicine applications in both therapeutics and diagnostics.Here,I will discuss two examples at the molecular and cellular levels:(1)mechanical regulation of epigenomics for cell reprogramming,and(2)engineering the mechanical properties of artificial antigen-presenting cells(APCs)for immune cell modulation and cancer therapy.Cell memory of its identity is determined by the epigenetic state of the cells.However,how cells control the epigenetic state and thus cell fate is not well understood,and how mechanical factors such as surface topography,cell morphology,mechanical properties of the extracellular matrix(ECM),and the mechanical deformation of cells regulate the epigenetic state is not clear.In an early study,we showed that biophysical cues,in the form of parallel microgrooves on the surface of cell-adhesive substrates,can replace the effects of small-molecule epigenetic modifiers and significantly improve reprogramming efficiency from fibroblasts to induced pluripotent stem cells.The mechanism relies on the mechanomodulation of the cells’epigenetic state through the activity of histone deacetylase and H3 methyltransferase.We also showed that microtopography promotes a mesenchymal-to-epithelial transition in adult fibroblasts.Nanofibrous scaffolds with aligned fiber orientation produce effects similar to those produced by microgrooves,suggesting that changes in cell morphology may be responsible for the modulation of the epigenetic state.The effects of micro/nanopatterned surfaces may be related to the reduction of intracellular tension and cell adhesion.Indeed,the reduction of actin cytoskeletal tension or cell adhesion at the early phase of reprogramming suppresses the expression of mesenchymal genes,promotes a more open chromatin structure,and significantly enhances the efficiency of induced neuronal(i N)conversion.Specifically,the reduction of intracellular tension or cell adhesion not only modulates global epigenetic marks but also decreases DNA methylation and heterochromatin marks while increasing euchromatin marks at the promoter of neuronal genes,thus enhancing the accessibility for gene activation.Finally,micro-and nano-topographic surfaces that reduce cell adhesion enhance i N reprogramming.These novel findings suggest that the actin cytoskeleton and focal adhesions play an important role in epigenetic regulation for cell fate determination,which may lead to biomaterialbased approaches for more effective cell reprogramming.In addition,matrix stiffness also regulates cell reprogramming,which acts as a biphasic regulator of the epigenetic state and fibroblast-to-neuron conversion efficiency,maximized at an intermediate stiffness of 20 k Pa.ATAC sequencing analysis shows the same trend of chromatin accessibility to neuronal genes at these stiffness levels.Concurrently,we observe peak levels of histone acetylation and histone acetyltransferase(HAT)activity in the nucleus on 20 k Pa matrices,and inhibiting HAT activity abolishes matrix stiffness effects.G-actin and cofilin,the co-transporters shuttling HAT into the nucleus,rise with decreasing matrix stiffness;however,reduced importin-9 on soft matrices limits nuclear transport.These two factors result in a biphasic regulation of HAT transport into the nucleus,which is directly demonstrated on matrices with dynamically tunable stiffness.Furthermore,we find that the regulation of the epigenetic state by the viscoelastic matrix is more pronounced on softermatrices.Cells on viscoelastic matrices exhibit larger nuclei,increased nuclear lamina ruffling,loosely organized chromatin,and faster chromatin dynamics compared to those on elastic matrices.These changes are accompanied by a global increase in euchromatic marks and a local increase in chromatin accessibility at the cis-regulatory elements associated with neuronal and pluripotent genes.Consequently,viscoelastic matrices enhance the efficiency of reprogramming fibroblasts into neurons and induced pluripotent stem cells,respectively.Together,our findings demonstrate the key roles of matrix viscoelasticity in regulating the epigenetic state and uncover a new mechanism of biophysical regulation of chromatin and cell reprogramming,with implications for designing smart materials to engineer cell fate.The viscoelasticity of biomaterials not only regulates cell adhesion and the epigenetic state but also modulates other ligand-receptor interactions such as T cell receptor activation.We developed a scalable microfluidic platform to fabricate synthetic viscoelastic activating cells(Syn VACs)with programmable mechanical and chemical properties.We demonstrated that the viscoelastic nature of Syn VACs significantly impacts T cell functionality.Compared to rigid or elastic microspheres,Syn VACs greatly enhance human T cell expansion with drastic CD8+T cell generation while suppressing regulatory T cell formation,resulting in enhanced tumor-killing capability.Notably,expanding chimeric antigen receptor(CAR)-T cells with Syn VACs achieves approximately 90%CAR transduction efficiency and leads to a six-fold increase in T memory stem cells.These engineered CAR-T cells exhibit superior efficacy in eliminating tumor cells,not only in a human lymphoma mouse model but also in a solid tumor xenograft mouse model of ovarian cancer.Additionally,Syn VAC-expanded CAR-T cells persist for longer periods in vivo to suppress tumor growth and recurrence.These findings underscore the crucial role of mechanical signals in T cell engineering and highlight the potential of the Syn VAC platform in CAR-T therapy and broad immunoengineering applications.These examples of mechanical regulation of cells not only unravel the underlying mechanisms of mechanotransduction in various cells,but also have tremendous potential to translate into therapeutic applications.
文摘It has been 53 years since the first volume of Acta Veterinaria et Zootechnica Sinica(Chinese Journal of Animal and Veterinary Sciences,CJAVS)was published.The Journal has earned its reputation by presenting high-level academic and instructive papers,technical reports,and achievements in Chinese,but its influence is still limited to its primary audience,in China.In recent years,international trade of animals and their products have expanded,
