To mitigate the sand burial of highways in sandy regions,a separated subgrade design was widely adopted in the embankments of high-grade highways,but the problem of sand deposition on subgrade slopes and pavements sti...To mitigate the sand burial of highways in sandy regions,a separated subgrade design was widely adopted in the embankments of high-grade highways,but the problem of sand deposition on subgrade slopes and pavements still happens frequently.Based on the theory of wind-sand two-phase flow,this paper constructed a three-dimensional model of the separated subgrade,the wind-sand flow transport law around the subgrade with varying median strip widths and concave depths was simulated by Fluent software.After comparison and analysis of seven subgrade models,the flow field distribution,wind speed horizontal variation,and erosion-deposition characteristics were investigated.The findings are as follows:(1)The width of the median strip in the separated subgrade had significant influences on the wind-sand flow.The smooth passage of wind-sand flow over the road surface was facilitated with the increase of the median strip width.However,sand deposition in the median strip happened.It can lead to secondary sand damage of downwind subgrade and increase the work load of road sand removal for subsequent maintenance.(2)The obstruction to airflow and sand accumulation was aggravated with greater concave depth of the median strip.Therefore,it is advisable to minimize the concave depth of the median strip in case of more sand damage.(3)A median strip width exceeding 12 m(possibly without guardrails)for an integral embankment without enough road land is recommended.Conversely,median strip width of over 40 m for separate subgrade with unrestricted land is suggested.(4)In the case of sand deposition in the existing separated subgrade,the median strip can be filled by sand deposition or other materials,then was covered with gravel to form a flat ground like Gobi smooth surface,which can let the wind-blown sand flow pass through the subgrade section without sand deposition.展开更多
To address the challenges associated with existing separated zone oil production technologies,such as incompatibility with pump inspection operations,short effective working life,and poor communication reliability,an ...To address the challenges associated with existing separated zone oil production technologies,such as incompatibility with pump inspection operations,short effective working life,and poor communication reliability,an innovative electromagnetic coupling intelligent zonal oil production technology has been proposed.The core and accessory tools have been developed and applied in field tests.This technology employs a pipe string structure incorporation a release sub,which separates the production and allocation pipe strings.When the two strings are docked downhole,electromagnetic coupling enables close-range wireless transmission of electrical power and signals between the strings,powering multiple downhole intelligent production allocators(IPAs)and enabling two-way communication.Core tools adapted to the complex working conditions downhole were developed,including downhole electricity&signal transmission equipment based on electromagnetic coupling(EST),IPAs,and ground communication controllers(GCCs).Accessory tools,including large-diameter release sub anchor and cable-crossing packers,have also been technically finalized.Field tests conducted on ten wells in Daqing Oilfield demonstrated that the downhole docking of the two strings was convenient and reliable,and the EST worked stably.Real-time monitoring of flow rate,pressure and temperature in separate layers and regulation of zonal fluid production were also achieved.This technology has enhanced reservoir understanding and achieved practical production results of increased oil output with reduced water cut.展开更多
The development of degradable and chemically recyclable polymers is a promising strategy to address pressing environmental and resource-related challenges.Despite significant progress,there is a need for continuous de...The development of degradable and chemically recyclable polymers is a promising strategy to address pressing environmental and resource-related challenges.Despite significant progress,there is a need for continuous development of such recyclable polymers.Herein,PPDOPLLA-PU copolymers were synthesized from poly(p-dioxanone)-diol(PPDO-diol)and poly(L-lactide)-diol(PLLA-diol)by chain extension reaction.The chemical structures and microphase structures of PPDO-PLLA-PU were characterized,and their crystalline properties,mechanical properties,and degradation behaviors were further investigated.Significantly,the distribution of PLLA phase in the copolymer matrix showed a rod-like microstructure with a slight orientation,despite the thermodynamic incompatibility of PPDO and PLLA segments.Moreover,on the basis of this microphase separation,PPDO spherulites can crystallize using the interface of the two phases as nucleation sites.Accordingly,the combined effect of above two contributes to the enhanced mechanical properties.In addition,PPDO-PLLA-PU copolymers have good processability and recyclability,making them valuable for a wide range of applications.展开更多
Metal-free organic emitters,characterized by their thermally activated delayed fluorescence(TADF)properties,offer considerable promise for the creation of highly efficient organic light-emitting diodes(OLEDs).Recently...Metal-free organic emitters,characterized by their thermally activated delayed fluorescence(TADF)properties,offer considerable promise for the creation of highly efficient organic light-emitting diodes(OLEDs).Recently,Shao et al.presented a novel excited state intramolecular proton transfer(ESIPT)system BrA-HBI,demonstrating an emission quantum yield of up to 50%[Adv.Funct.Mater.32,2201256(2022)].However,many open issues cannot be answered solely by experimental means only and require detailed theoretical investigations.For instance,what causes the activation of TADF from the Keto^(*) tautomer and leads to fluorescence quenching in the Enol^(*)form?Herein,we provide a theoretical investigation on the TADF mechanism of the BrA-HBI molecule by optimally tuned range-separated functionals.Our findings reveal that ESIPT occurs in the BrA-HBI molecule.Moreover,we have disclosed the reason for the fluorescence quenching of the Enol^(*)form and determined that the T_(2)state plays a dominant role in the TADF phenomenon.In addition,double hybrid density functionals method was utilized to verify the reliability of optimally tuned range separation functionals on the calculation of the TADF mechanism in BrA-HBI.These findings not only provide a theoretical reference for development of highly efficient organic light-emitting diodes,but also demonstrate the effectiveness of the optimally tuned range-separated functionals in predicting the luminescence properties of TADF molecules.展开更多
Finned-tube heat exchanger(FTHE)is often used as an evaporator in commercial products of separated heat pipe(SHP).The working conditions of FTHE in gravity-assisted SHP are significantly different from those working i...Finned-tube heat exchanger(FTHE)is often used as an evaporator in commercial products of separated heat pipe(SHP).The working conditions of FTHE in gravity-assisted SHP are significantly different from those working in refrigerators and air conditioners.Although FTHE is widely used in commercial products of SHP,previous research on its characteristics is very limited.In this paper,a mathematical model for a SHP with FTHE as the evaporator and plate heat exchanger as the condenser is established and verified with experiments.Parametric analyses are carried out to investigate the influences of evaporator design parameters:air inlet velocity,number of tube rows,tube diameter,and fin pitch.With the increasing of air velocity,number of tube rows and tube diameter,and the decreasing of fin pitch,the heat transfer rate increases,while the energy efficiency ratio(EER)decreases monotonically.Using the total cost of the ten-year life cycle as the performance index,the structure parameters of the evaporator with a given heat transfer rate are optimized by the method of orthogonal experimental design.It is found that the total cost can differ as large as nearly ten times between groups.Among the three factors investigated,the number of tube rows has a significant impact on the total cost of the evaporator.With more tube rows,the total cost will be less.The impacts of fin pitch and tube diameter are insignificant.These results are of practical importance for the engineering design of FTHE in gravity-assisted SHP.展开更多
[Objectives]To investigate the effect and mechanism of Dachengqi Decoction and separated decoction on incomplete intestinal obstruction in rats.[Methods]80 healthy SD rats were selected to establish incomplete intesti...[Objectives]To investigate the effect and mechanism of Dachengqi Decoction and separated decoction on incomplete intestinal obstruction in rats.[Methods]80 healthy SD rats were selected to establish incomplete intestinal obstruction model by silk ligation.The dosage was 20 mL/kg for 3 d,and the damage index of ileocecal mucosa was analyzed;the morphology of ileocecal mucosa was observed by HE staining;the serum levels of IL-1α,IL-1β,IL-6,IL-18,Ach,NO,ET,IL-1,TNF-αand ultra-micro Na+-K+-ATPase were detected by ELISA.[Results]Compared with the model group,the mucosal damage index of Dachengqi Decoction and each separated decoction group decreased significantly(P<0.05);compared with the normal group and sham operation group,the serum level of IL-1,IL-6,TNF-αand other factors in the model group increased significantly(P<0.05);compared with the model group,the serum IL-1,IL-6 and TNF-αsecretion levels of rats in Dachengqi Decoction group and separated decoction group decreased(P<0.01).[Conclusions]Dachengqi Decoction and each separated decoction can effectively improve intestinal tissue pathological damage in the incomplete intestinal obstruction model rats,and reduce the inflammatory reaction in the rat body.展开更多
In flowering plants, callose(β-1,3-glucan) plays a vital role in pollen development, especially in the separation and development of microspores. However, the molecular mechanism of callose deposition during rice pol...In flowering plants, callose(β-1,3-glucan) plays a vital role in pollen development, especially in the separation and development of microspores. However, the molecular mechanism of callose deposition during rice pollen development remains unclear. In this study, we isolated and characterized a novel rice pollen defective mutant, non-separated microspores 1(nsm1), which produced “dyad” or “tetrad” pollen grains. Cytological analysis indicated disrupted interstitial callose deposition at the cell plate of dyads and tetrads in nsm1 pollens. This disruption caused sporopollenin to be massively deposited outside of the junction where the interstitial callose wall connected with the peripheral callose wall, or unevenly distributed on the interstitial pollen primexine at the late meiosis stage. Consequently, an excess tectum-like layer was formed outside of the junction, connecting with the tectum of two microspores during later developmental stages, which prevented the separation of microspores. Additionally, in the linkage area, the tectum of two microspores gradually fused or degenerated, resulting in a decreased contact area between microspores and the anther locule. Therefore, the defect in callose deposition resulted in unsuccessful separation of microspores, abnormal deposition of pollen exine, and also affected the accumulation of materials in microspores, resulting in pollen semi-sterility. NSM1, encoding a callose synthase located in the Golgi body, is ubiquitously expressed in anthers with its peak expression at the young microspore stage. The in vitro enzyme activity assay confirmed that NSM1 possesses callose synthase activity, and the enzyme activity in the nsm1 mutants was significantly reduced.Phylogenetic analysis indicated that NSM1 and its orthologs play a highly conserved role in callose biosynthesis among plant species. Taken together, we propose that NSM1 plays an essential role in male meiotic callose synthesis and later pollen wall development.展开更多
All solid-state lithium metal batteries(ASSLMBs)based on polymer solid electrolyte and lithium metal anode have attracted much attention due to their high energy density and intrinsic safety.However,the low ionic cond...All solid-state lithium metal batteries(ASSLMBs)based on polymer solid electrolyte and lithium metal anode have attracted much attention due to their high energy density and intrinsic safety.However,the low ionic conductivity at room temperature and poor mechanical properties of the solid polymer electrolyte result in increased polarization and poor cycling stability of the Li metal batteries.In order to improve the ionic conductivity at room temperature while maintaining mechanical strength,we combine the conductivity of short chain polyethylene oxide(PEO)and strength of styrene-maleic anhydride copolymer(SMA)to obtain a grafted block copolymer with nanophase separation structure,which has room temperature ionic conductivity up to 1.14×10^(-4)S/cm and tensile strength up to 1.4 MPa.Li||Li symmetric cell can work stably for more than 1500 h under the condition of 0.1 mA/cm^(2).Li||LiFePO_(4)full cells can deliver a high capacity of 151.4 mAh/g at 25℃and 0.2 C/0.2 C charge/discharge conditions,showing 85.6%capacity retention after 400 cycles.Importantly,the all solid state Li||LiFePO_(4)pouch cell shows excellent safety performance under different abuse conditions.These results demonstrate that the nanophase separated,grafted alternate copolymer electrolyte has huge potential for application in Li metal batteries.展开更多
In this paper we shall offer a separation axiom for frames inspired by the Hausdorff separation axiom for topological spaces. We call it separated condition. This is a condition on topology OX equivalent to the ...In this paper we shall offer a separation axiom for frames inspired by the Hausdorff separation axiom for topological spaces. We call it separated condition. This is a condition on topology OX equivalent to the T O space X being Hausdorff. The class of separated frames includes that of strong Hausdorff frames and that of S frames. We shall show that the class of separated frames is a class closed under the formation of coproducts and subspaces, and the space Fil( L ) is Hausdorff for any separated frame L . Therefore there is a contravariant adjunction between the category TOP 2 of Hausdorff topological spaces and the category FRAM 2 of separated frames.展开更多
Suppression of photogenerated charge recombination is crucial for efficient photocatalytic hydrogen production.Homojunctions have garnered more attention than heterojunctions due to their superior crystal binding and ...Suppression of photogenerated charge recombination is crucial for efficient photocatalytic hydrogen production.Homojunctions have garnered more attention than heterojunctions due to their superior crystal binding and band structure matching.However,most homojunctions suffer from redox interference caused by continuous oxidizing and reducing phases that impede the ability to improve photocatalytic activity.Consequently,the preparation of homojunction photocatalysts with completely spatial separation of both in charge and redox phases remains challenging.Here,the preparation of a two-dimensional(2D)homojunction CeO_(2) with a back-to-back geometry and fully separated oxidizing and reducing phases is reported.The prepared CeO_(2) is composed of nanosheets with twocontrasting smooth and rough surfaces.Experimental and theoretical results indicate that the rough surface contains more highly reducing CeO_(2){220}and strongly visiblelight-absorbing CeO_(2){200}facets than the smooth surface.The 2D homojunction CeO_(2) produces three-times more hydrogen than normal CeO_(2) nanosheets,and even more than that of CeO_(2) nanosheets loaded with gold nanoparticles.This work presents a new homojunction photocatalyst model with completely spatial separation of both in charge and redox phases that is expected to inspire further research into homojunction photocatalysts.展开更多
Numerical studies of the flow past a circular cylinder at Reynolds number 1.4 × 105 and NACA0021 airfoil at the angle of attack 60° have been carried out by scale-adaptive simulation （SAS） and detached edd...Numerical studies of the flow past a circular cylinder at Reynolds number 1.4 × 105 and NACA0021 airfoil at the angle of attack 60° have been carried out by scale-adaptive simulation （SAS） and detached eddy simu- lation （DES）, in comparison with the existing experimental data. The new version of the model developed by Egorov and Menter is assessed, and advantages and disadvantages of the SAS simulation are analyzed in detail to provide guidance for industrial application in the future. Moreover, the mechanism of the scale-adaptive characteristics in separated regions is discussed, which is obscure in previous analyses. It is con- cluded that： the mean flow properties satisfactorily agree with the experimental results for the SAS simulation, although the prediction of the second order turbulent statistics in the near wake region is just reasonable. The SAS model can produce a larger magnitude of the turbulent kinetic energy in the recir- culation bubble, and, consequently, a smaller recirculation region and a more rapid recovery of the mean velocity out- side the recirculation region than the DES approach with the same grid resolution. The vortex shedding is slightly less irregular with the SAS model than with the DES approach, probably due to the higher dissipation of the SAS simulation under the condition of the coarse mesh.展开更多
This article outlines the development of downhole monitoring and data transmission technology for separated zone water injection in China.According to the development stages,the principles,operation processes,adaptabi...This article outlines the development of downhole monitoring and data transmission technology for separated zone water injection in China.According to the development stages,the principles,operation processes,adaptability and application status of traditional downhole data acquisition method,cable communications and testing technology,cable-controlled downhole parameter real-time monitoring communication method and downhole wireless communication technology are introduced in detail.Problems and challenges of existing technologies in downhole monitoring and data transmission technology are pointed out.According to the production requirement,the future development direction of the downhole monitoring and data transmission technology for separated zone water injection is proposed.For the large number of wells adopting cable measuring and adjustment technology,the key is to realize the digitalization of downhole plug.For the key monitoring wells,cable-controlled communication technology needs to be improved,and downhole monitoring and data transmission technology based on composite coiled tubing needs to be developed to make the operation more convenient and reliable.For large-scale application in oil fields,downhole wireless communication technology should be developed to realize automation of measurement and adjustment.In line with ground mobile communication network,a digital communication network covering the control center,water distribution station and oil reservoir should be built quickly to provide technical support for the digitization of reservoir development.展开更多
Acryloyl terminated Poly (ethyleneoxide)macromonomers (PEO-A) with different PEO chain lengths have been prepared by deactivation of PEO alkoxide with acryloyl chloride. A new kind of amphiphilic polystyrene-g-poly (e...Acryloyl terminated Poly (ethyleneoxide)macromonomers (PEO-A) with different PEO chain lengths have been prepared by deactivation of PEO alkoxide with acryloyl chloride. A new kind of amphiphilic polystyrene-g-poly (ethylene oxide)graft copolymer containing both microphase separated and PEO side chain structures has been synthesized from radical copolymerization of PEO-A macromonomer with styrene. After careful purification by a newly-developed method called 'selective dissolution', the well-defined structure of the purified copolymers was confirmed by IR, ~1H-NMR and GPC. Various experimental parameters controlling the copolymerization were studied in detail. The results indicated that the feed ratio of styrene to macromonomer(S/M) was the most important determining factor for the composition of the copolymers. A detailed 'comb- model' was proposed to describe the molecular structure of the graft copolymers. Finally, this amphiphilic graft copolymers may readily form microphase separated structures as clearly indicated by transmission electron microscopy.展开更多
The process through which a laminar flow undergoes transition to turbulence is of great fundamental and practical interest. Such a process is hugely complex as there are many diverse routes for a laminar flow to becom...The process through which a laminar flow undergoes transition to turbulence is of great fundamental and practical interest. Such a process is hugely complex as there are many diverse routes for a laminar flow to become turbulent flow. The transition process is usually initiated by flow instabilities—a primary instability stage followed by a secondary instability stage. This forms a rational framework for the early stage of a transition process and it is crucially important to understand the physics of instabilities leading to turbulence. This article reviews the results of studies on secondary instability of separated shear layers in separation bubbles and summaries the current status of our understanding in this area.展开更多
By introducing a more general auxiliary ordinary differential equation （ODE）, a modified variable separated ODE method is developed for solving the mKdV-sinh-Gordon equation. As a result, many explicit and exact sol...By introducing a more general auxiliary ordinary differential equation （ODE）, a modified variable separated ODE method is developed for solving the mKdV-sinh-Gordon equation. As a result, many explicit and exact solutions including some new formal solutions are successfully picked up for the mKdV-sinh-Gordon equation by this approach.展开更多
The effect of Fructus Mume formula and its separated prescription extract on insulin resis- tance in type 2 diabetic rats was investigated. The rat model of type 2 diabetes was established by feed- ing on a high-fat d...The effect of Fructus Mume formula and its separated prescription extract on insulin resis- tance in type 2 diabetic rats was investigated. The rat model of type 2 diabetes was established by feed- ing on a high-fat diet for 8 weeks and by subsequently intravenous injection of small doses of strepto- zotocin. Rats in treatment groups, including the Fructus Mume formula treatment group （FM）, the cold property herbs of Fructus Mume formula treatment group （CFM）, the warm property herbs of Fructus Mume formula treatment group （WFM）, were administrated with Fructus Mume formula and its sepa- rated prescription extract by gavage, while the rats in diabetic model group （DM） and metformin group （MET） were given by gavage with normal saline and metformin correspondingly. The body weight be- fore and after treatment was measured, and the oral glucose tolerance test （OGTT） and the insulin re- lease test （IRT） were performed. The homeostasis model assessment-insulin resistance index （HOMA-IR） was calculated. The protein and mRNA expression levels of Insr, β-arrestin-2, Its-1 and Glut-4 in the liver, skeletal muscle and fat tissues were detected by using Western blotting and RT-PCR respectively. The results demonstrated that, as compared with DM group, OGTT, IRT （0 h, 1 h） levels and HOMR-IR in treatment groups were all reduced, meanwhile their protein and mRNA expression levels of Insr, Irs-1 and Glut-4 in the liver, skeletal muscle and fat tissues were obviously increased, and their protein and mRNA expression levels of β-arrestin-2 in the liver and skeletal muscle tissues were also markedly increased. It was suggested that the Fructus Mume formula and its separated prescription extracts could effectively improve insulin resistance in type 2 diabetic rats, which might be related to the up-regulated expression of Insr, Irs-1 and Glut-4 in the liver, skeletal muscle and fat tissues, and β-arrestin-2 in the liver and skeletal muscle tissues.展开更多
Accurate prediction of unsteady separated turbulent flows remains one of the toughest tasks and a practi cal challenge for turbulence modeling. In this paper, a 2D flow past a circular cylinder at Reynolds number 3,90...Accurate prediction of unsteady separated turbulent flows remains one of the toughest tasks and a practi cal challenge for turbulence modeling. In this paper, a 2D flow past a circular cylinder at Reynolds number 3,900 is numerically investigated by using the technique of unsteady RANS （URANS）. Some typical linear and nonlinear eddy viscosity turbulence models （LEVM and NLEVM） and a quadratic explicit algebraic stress model （EASM） are evaluated. Numerical results have shown that a high-performance cubic NLEVM, such as CLS, are superior to the others in simulating turbulent separated flows with unsteady vortex shedding.展开更多
This paper presents a separated law of hardening in plasticity with strain gradient effects. The value of the length parameter l contained in this model was estimated from the experimental data for copper.
In this paper, an oscillation frequency equation for a pizoelectric sensor with two separated-electrodes is theoretically derived and experimentally verified. The correlatione of the oscillation frequency and the liqu...In this paper, an oscillation frequency equation for a pizoelectric sensor with two separated-electrodes is theoretically derived and experimentally verified. The correlatione of the oscillation frequency and the liquid properties are investigated.展开更多
基金supported by the Third Xinjiang Scientific Expedition and Research Program-Investigation and Risk Assessment of Drought and Aeolian Disasters in Tarim River Basin(No.2021xjkk0300)the National Natural Science Foundation of China(No.62466056)the subject of'the technical scheme and application demonstration of sand disaster prevention and control of Xinjiang expressway to engineering practice,Xinjiang Transportation Investment(Group)Co.,Ltd.(No.XJJTZKX-FWCG-202401-0043).
文摘To mitigate the sand burial of highways in sandy regions,a separated subgrade design was widely adopted in the embankments of high-grade highways,but the problem of sand deposition on subgrade slopes and pavements still happens frequently.Based on the theory of wind-sand two-phase flow,this paper constructed a three-dimensional model of the separated subgrade,the wind-sand flow transport law around the subgrade with varying median strip widths and concave depths was simulated by Fluent software.After comparison and analysis of seven subgrade models,the flow field distribution,wind speed horizontal variation,and erosion-deposition characteristics were investigated.The findings are as follows:(1)The width of the median strip in the separated subgrade had significant influences on the wind-sand flow.The smooth passage of wind-sand flow over the road surface was facilitated with the increase of the median strip width.However,sand deposition in the median strip happened.It can lead to secondary sand damage of downwind subgrade and increase the work load of road sand removal for subsequent maintenance.(2)The obstruction to airflow and sand accumulation was aggravated with greater concave depth of the median strip.Therefore,it is advisable to minimize the concave depth of the median strip in case of more sand damage.(3)A median strip width exceeding 12 m(possibly without guardrails)for an integral embankment without enough road land is recommended.Conversely,median strip width of over 40 m for separate subgrade with unrestricted land is suggested.(4)In the case of sand deposition in the existing separated subgrade,the median strip can be filled by sand deposition or other materials,then was covered with gravel to form a flat ground like Gobi smooth surface,which can let the wind-blown sand flow pass through the subgrade section without sand deposition.
基金Supported by the National Natural Science Foundation of China(52374067)PetroChina Scientific Research and Technology Development Project(2021ZG12)PetroChina Technology Project(2023ZZ09).
文摘To address the challenges associated with existing separated zone oil production technologies,such as incompatibility with pump inspection operations,short effective working life,and poor communication reliability,an innovative electromagnetic coupling intelligent zonal oil production technology has been proposed.The core and accessory tools have been developed and applied in field tests.This technology employs a pipe string structure incorporation a release sub,which separates the production and allocation pipe strings.When the two strings are docked downhole,electromagnetic coupling enables close-range wireless transmission of electrical power and signals between the strings,powering multiple downhole intelligent production allocators(IPAs)and enabling two-way communication.Core tools adapted to the complex working conditions downhole were developed,including downhole electricity&signal transmission equipment based on electromagnetic coupling(EST),IPAs,and ground communication controllers(GCCs).Accessory tools,including large-diameter release sub anchor and cable-crossing packers,have also been technically finalized.Field tests conducted on ten wells in Daqing Oilfield demonstrated that the downhole docking of the two strings was convenient and reliable,and the EST worked stably.Real-time monitoring of flow rate,pressure and temperature in separate layers and regulation of zonal fluid production were also achieved.This technology has enhanced reservoir understanding and achieved practical production results of increased oil output with reduced water cut.
基金financially supported by the National Key R&D Program of China(No.2021YFB3801901)the National Natural Science Foundation of China(Nos.52403138 and U19A2095)+1 种基金Institutional Research Fund from Sichuan University(No.2020SCUNL205)Fundamental Research Funds for the Central Universities,and 111 Project(No.B20001)。
文摘The development of degradable and chemically recyclable polymers is a promising strategy to address pressing environmental and resource-related challenges.Despite significant progress,there is a need for continuous development of such recyclable polymers.Herein,PPDOPLLA-PU copolymers were synthesized from poly(p-dioxanone)-diol(PPDO-diol)and poly(L-lactide)-diol(PLLA-diol)by chain extension reaction.The chemical structures and microphase structures of PPDO-PLLA-PU were characterized,and their crystalline properties,mechanical properties,and degradation behaviors were further investigated.Significantly,the distribution of PLLA phase in the copolymer matrix showed a rod-like microstructure with a slight orientation,despite the thermodynamic incompatibility of PPDO and PLLA segments.Moreover,on the basis of this microphase separation,PPDO spherulites can crystallize using the interface of the two phases as nucleation sites.Accordingly,the combined effect of above two contributes to the enhanced mechanical properties.In addition,PPDO-PLLA-PU copolymers have good processability and recyclability,making them valuable for a wide range of applications.
基金supported by the National Natural Science Foundation of China(Grant No.12174149)。
文摘Metal-free organic emitters,characterized by their thermally activated delayed fluorescence(TADF)properties,offer considerable promise for the creation of highly efficient organic light-emitting diodes(OLEDs).Recently,Shao et al.presented a novel excited state intramolecular proton transfer(ESIPT)system BrA-HBI,demonstrating an emission quantum yield of up to 50%[Adv.Funct.Mater.32,2201256(2022)].However,many open issues cannot be answered solely by experimental means only and require detailed theoretical investigations.For instance,what causes the activation of TADF from the Keto^(*) tautomer and leads to fluorescence quenching in the Enol^(*)form?Herein,we provide a theoretical investigation on the TADF mechanism of the BrA-HBI molecule by optimally tuned range-separated functionals.Our findings reveal that ESIPT occurs in the BrA-HBI molecule.Moreover,we have disclosed the reason for the fluorescence quenching of the Enol^(*)form and determined that the T_(2)state plays a dominant role in the TADF phenomenon.In addition,double hybrid density functionals method was utilized to verify the reliability of optimally tuned range separation functionals on the calculation of the TADF mechanism in BrA-HBI.These findings not only provide a theoretical reference for development of highly efficient organic light-emitting diodes,but also demonstrate the effectiveness of the optimally tuned range-separated functionals in predicting the luminescence properties of TADF molecules.
基金supported by Archaeological Artifact Protection Technology Project of Zhejiang Province(NO2021013).
文摘Finned-tube heat exchanger(FTHE)is often used as an evaporator in commercial products of separated heat pipe(SHP).The working conditions of FTHE in gravity-assisted SHP are significantly different from those working in refrigerators and air conditioners.Although FTHE is widely used in commercial products of SHP,previous research on its characteristics is very limited.In this paper,a mathematical model for a SHP with FTHE as the evaporator and plate heat exchanger as the condenser is established and verified with experiments.Parametric analyses are carried out to investigate the influences of evaporator design parameters:air inlet velocity,number of tube rows,tube diameter,and fin pitch.With the increasing of air velocity,number of tube rows and tube diameter,and the decreasing of fin pitch,the heat transfer rate increases,while the energy efficiency ratio(EER)decreases monotonically.Using the total cost of the ten-year life cycle as the performance index,the structure parameters of the evaporator with a given heat transfer rate are optimized by the method of orthogonal experimental design.It is found that the total cost can differ as large as nearly ten times between groups.Among the three factors investigated,the number of tube rows has a significant impact on the total cost of the evaporator.With more tube rows,the total cost will be less.The impacts of fin pitch and tube diameter are insignificant.These results are of practical importance for the engineering design of FTHE in gravity-assisted SHP.
基金2023 Young and Middle-aged University Teachers Basic Scientific Research Ability Improvement Project in Guangxi(2023KY0299)High-level Key Discipline Construction Project of Traditional Chinese Medicine of National Administration of Traditional Chinese Medicine(zyyzdxk-2023165)+3 种基金Talent Training Project of Guangxi International Zhuang Medicine Hospital—"Young Seedling Project"(2022001)Guangxi Traditional Chinese Medicine Multidisciplinary and Interdisciplinary Innovation Team Project(GZKJ2309)High-level Talent Cultivation Innovation Team Funding Project of Guangxi University of Chinese Medicine(2022A008)2023 Three-Year Action Plan Project for High-Level Talent Team Construction of Guangxi International Zhuang Medicine Hospital(GZCX20231203,GZCX20231202).
文摘[Objectives]To investigate the effect and mechanism of Dachengqi Decoction and separated decoction on incomplete intestinal obstruction in rats.[Methods]80 healthy SD rats were selected to establish incomplete intestinal obstruction model by silk ligation.The dosage was 20 mL/kg for 3 d,and the damage index of ileocecal mucosa was analyzed;the morphology of ileocecal mucosa was observed by HE staining;the serum levels of IL-1α,IL-1β,IL-6,IL-18,Ach,NO,ET,IL-1,TNF-αand ultra-micro Na+-K+-ATPase were detected by ELISA.[Results]Compared with the model group,the mucosal damage index of Dachengqi Decoction and each separated decoction group decreased significantly(P<0.05);compared with the normal group and sham operation group,the serum level of IL-1,IL-6,TNF-αand other factors in the model group increased significantly(P<0.05);compared with the model group,the serum IL-1,IL-6 and TNF-αsecretion levels of rats in Dachengqi Decoction group and separated decoction group decreased(P<0.01).[Conclusions]Dachengqi Decoction and each separated decoction can effectively improve intestinal tissue pathological damage in the incomplete intestinal obstruction model rats,and reduce the inflammatory reaction in the rat body.
基金supported by grants from the National Natural Science Foundation of China (31971871)Open Competition Mechanism to Select the Best Candidates Fund of Jiangsu Province (JBGS[2021]012)Zhongshan Biological Breeding Laboratory (BM2022008-01,BM2022008-03).
文摘In flowering plants, callose(β-1,3-glucan) plays a vital role in pollen development, especially in the separation and development of microspores. However, the molecular mechanism of callose deposition during rice pollen development remains unclear. In this study, we isolated and characterized a novel rice pollen defective mutant, non-separated microspores 1(nsm1), which produced “dyad” or “tetrad” pollen grains. Cytological analysis indicated disrupted interstitial callose deposition at the cell plate of dyads and tetrads in nsm1 pollens. This disruption caused sporopollenin to be massively deposited outside of the junction where the interstitial callose wall connected with the peripheral callose wall, or unevenly distributed on the interstitial pollen primexine at the late meiosis stage. Consequently, an excess tectum-like layer was formed outside of the junction, connecting with the tectum of two microspores during later developmental stages, which prevented the separation of microspores. Additionally, in the linkage area, the tectum of two microspores gradually fused or degenerated, resulting in a decreased contact area between microspores and the anther locule. Therefore, the defect in callose deposition resulted in unsuccessful separation of microspores, abnormal deposition of pollen exine, and also affected the accumulation of materials in microspores, resulting in pollen semi-sterility. NSM1, encoding a callose synthase located in the Golgi body, is ubiquitously expressed in anthers with its peak expression at the young microspore stage. The in vitro enzyme activity assay confirmed that NSM1 possesses callose synthase activity, and the enzyme activity in the nsm1 mutants was significantly reduced.Phylogenetic analysis indicated that NSM1 and its orthologs play a highly conserved role in callose biosynthesis among plant species. Taken together, we propose that NSM1 plays an essential role in male meiotic callose synthesis and later pollen wall development.
基金financially supported by the National Natural Science Foundation of China(Nos.21771018,21875004,22108149)Beijing University of Chemical Technology(No.buctrC_(2)01901)+1 种基金Beijing Municipal Natural Science Foundation-Xiaomi Innovation Joint Fund(No.L223011)supported by the program“Research on key technologies of solid-state batteries-research and development of organic-inorganic composite solid-state electrolytes”from China Three Gorges Corporation(No.202103036)。
文摘All solid-state lithium metal batteries(ASSLMBs)based on polymer solid electrolyte and lithium metal anode have attracted much attention due to their high energy density and intrinsic safety.However,the low ionic conductivity at room temperature and poor mechanical properties of the solid polymer electrolyte result in increased polarization and poor cycling stability of the Li metal batteries.In order to improve the ionic conductivity at room temperature while maintaining mechanical strength,we combine the conductivity of short chain polyethylene oxide(PEO)and strength of styrene-maleic anhydride copolymer(SMA)to obtain a grafted block copolymer with nanophase separation structure,which has room temperature ionic conductivity up to 1.14×10^(-4)S/cm and tensile strength up to 1.4 MPa.Li||Li symmetric cell can work stably for more than 1500 h under the condition of 0.1 mA/cm^(2).Li||LiFePO_(4)full cells can deliver a high capacity of 151.4 mAh/g at 25℃and 0.2 C/0.2 C charge/discharge conditions,showing 85.6%capacity retention after 400 cycles.Importantly,the all solid state Li||LiFePO_(4)pouch cell shows excellent safety performance under different abuse conditions.These results demonstrate that the nanophase separated,grafted alternate copolymer electrolyte has huge potential for application in Li metal batteries.
文摘In this paper we shall offer a separation axiom for frames inspired by the Hausdorff separation axiom for topological spaces. We call it separated condition. This is a condition on topology OX equivalent to the T O space X being Hausdorff. The class of separated frames includes that of strong Hausdorff frames and that of S frames. We shall show that the class of separated frames is a class closed under the formation of coproducts and subspaces, and the space Fil( L ) is Hausdorff for any separated frame L . Therefore there is a contravariant adjunction between the category TOP 2 of Hausdorff topological spaces and the category FRAM 2 of separated frames.
基金financially supported by the National Natural Science Foundation of China (Nos.22205084 and21805191)the Start-Up Funding of Jiangsu University of Science and Technology (No.1112932203)+2 种基金Guangdong Basic and Applied Basic Research Foundation (No.2020A1515010982)Shenzhen Stable Support Project (No.20200812122947002)Shenzhen Peacock Plan (No.20210802524B)。
文摘Suppression of photogenerated charge recombination is crucial for efficient photocatalytic hydrogen production.Homojunctions have garnered more attention than heterojunctions due to their superior crystal binding and band structure matching.However,most homojunctions suffer from redox interference caused by continuous oxidizing and reducing phases that impede the ability to improve photocatalytic activity.Consequently,the preparation of homojunction photocatalysts with completely spatial separation of both in charge and redox phases remains challenging.Here,the preparation of a two-dimensional(2D)homojunction CeO_(2) with a back-to-back geometry and fully separated oxidizing and reducing phases is reported.The prepared CeO_(2) is composed of nanosheets with twocontrasting smooth and rough surfaces.Experimental and theoretical results indicate that the rough surface contains more highly reducing CeO_(2){220}and strongly visiblelight-absorbing CeO_(2){200}facets than the smooth surface.The 2D homojunction CeO_(2) produces three-times more hydrogen than normal CeO_(2) nanosheets,and even more than that of CeO_(2) nanosheets loaded with gold nanoparticles.This work presents a new homojunction photocatalyst model with completely spatial separation of both in charge and redox phases that is expected to inspire further research into homojunction photocatalysts.
基金the National Basic Research Program of China ("973" Project) (Grant No. 2009CB724104)
文摘Numerical studies of the flow past a circular cylinder at Reynolds number 1.4 × 105 and NACA0021 airfoil at the angle of attack 60° have been carried out by scale-adaptive simulation （SAS） and detached eddy simu- lation （DES）, in comparison with the existing experimental data. The new version of the model developed by Egorov and Menter is assessed, and advantages and disadvantages of the SAS simulation are analyzed in detail to provide guidance for industrial application in the future. Moreover, the mechanism of the scale-adaptive characteristics in separated regions is discussed, which is obscure in previous analyses. It is con- cluded that： the mean flow properties satisfactorily agree with the experimental results for the SAS simulation, although the prediction of the second order turbulent statistics in the near wake region is just reasonable. The SAS model can produce a larger magnitude of the turbulent kinetic energy in the recir- culation bubble, and, consequently, a smaller recirculation region and a more rapid recovery of the mean velocity out- side the recirculation region than the DES approach with the same grid resolution. The vortex shedding is slightly less irregular with the SAS model than with the DES approach, probably due to the higher dissipation of the SAS simulation under the condition of the coarse mesh.
基金Supported by the National Natural Science Foundation Science Center Project/Basic Science Center Project(72088101)PetroChina Scientific Research and Technology Development Project(2020B-4119,2021ZG12).
文摘This article outlines the development of downhole monitoring and data transmission technology for separated zone water injection in China.According to the development stages,the principles,operation processes,adaptability and application status of traditional downhole data acquisition method,cable communications and testing technology,cable-controlled downhole parameter real-time monitoring communication method and downhole wireless communication technology are introduced in detail.Problems and challenges of existing technologies in downhole monitoring and data transmission technology are pointed out.According to the production requirement,the future development direction of the downhole monitoring and data transmission technology for separated zone water injection is proposed.For the large number of wells adopting cable measuring and adjustment technology,the key is to realize the digitalization of downhole plug.For the key monitoring wells,cable-controlled communication technology needs to be improved,and downhole monitoring and data transmission technology based on composite coiled tubing needs to be developed to make the operation more convenient and reliable.For large-scale application in oil fields,downhole wireless communication technology should be developed to realize automation of measurement and adjustment.In line with ground mobile communication network,a digital communication network covering the control center,water distribution station and oil reservoir should be built quickly to provide technical support for the digitization of reservoir development.
基金Supported by the National Natural Science Foundation of China and the State Education Committee of China
文摘Acryloyl terminated Poly (ethyleneoxide)macromonomers (PEO-A) with different PEO chain lengths have been prepared by deactivation of PEO alkoxide with acryloyl chloride. A new kind of amphiphilic polystyrene-g-poly (ethylene oxide)graft copolymer containing both microphase separated and PEO side chain structures has been synthesized from radical copolymerization of PEO-A macromonomer with styrene. After careful purification by a newly-developed method called 'selective dissolution', the well-defined structure of the purified copolymers was confirmed by IR, ~1H-NMR and GPC. Various experimental parameters controlling the copolymerization were studied in detail. The results indicated that the feed ratio of styrene to macromonomer(S/M) was the most important determining factor for the composition of the copolymers. A detailed 'comb- model' was proposed to describe the molecular structure of the graft copolymers. Finally, this amphiphilic graft copolymers may readily form microphase separated structures as clearly indicated by transmission electron microscopy.
文摘The process through which a laminar flow undergoes transition to turbulence is of great fundamental and practical interest. Such a process is hugely complex as there are many diverse routes for a laminar flow to become turbulent flow. The transition process is usually initiated by flow instabilities—a primary instability stage followed by a secondary instability stage. This forms a rational framework for the early stage of a transition process and it is crucially important to understand the physics of instabilities leading to turbulence. This article reviews the results of studies on secondary instability of separated shear layers in separation bubbles and summaries the current status of our understanding in this area.
基金Project supported by the National Natural Science Foundation of China (Grant No 10672053)
文摘By introducing a more general auxiliary ordinary differential equation （ODE）, a modified variable separated ODE method is developed for solving the mKdV-sinh-Gordon equation. As a result, many explicit and exact solutions including some new formal solutions are successfully picked up for the mKdV-sinh-Gordon equation by this approach.
基金supported by grants from the National Natural Science Foundation of China(No.81273683)the Foundation of Hubei Provincial Health Department(No.2012Z-Y04)
文摘The effect of Fructus Mume formula and its separated prescription extract on insulin resis- tance in type 2 diabetic rats was investigated. The rat model of type 2 diabetes was established by feed- ing on a high-fat diet for 8 weeks and by subsequently intravenous injection of small doses of strepto- zotocin. Rats in treatment groups, including the Fructus Mume formula treatment group （FM）, the cold property herbs of Fructus Mume formula treatment group （CFM）, the warm property herbs of Fructus Mume formula treatment group （WFM）, were administrated with Fructus Mume formula and its sepa- rated prescription extract by gavage, while the rats in diabetic model group （DM） and metformin group （MET） were given by gavage with normal saline and metformin correspondingly. The body weight be- fore and after treatment was measured, and the oral glucose tolerance test （OGTT） and the insulin re- lease test （IRT） were performed. The homeostasis model assessment-insulin resistance index （HOMA-IR） was calculated. The protein and mRNA expression levels of Insr, β-arrestin-2, Its-1 and Glut-4 in the liver, skeletal muscle and fat tissues were detected by using Western blotting and RT-PCR respectively. The results demonstrated that, as compared with DM group, OGTT, IRT （0 h, 1 h） levels and HOMR-IR in treatment groups were all reduced, meanwhile their protein and mRNA expression levels of Insr, Irs-1 and Glut-4 in the liver, skeletal muscle and fat tissues were obviously increased, and their protein and mRNA expression levels of β-arrestin-2 in the liver and skeletal muscle tissues were also markedly increased. It was suggested that the Fructus Mume formula and its separated prescription extracts could effectively improve insulin resistance in type 2 diabetic rats, which might be related to the up-regulated expression of Insr, Irs-1 and Glut-4 in the liver, skeletal muscle and fat tissues, and β-arrestin-2 in the liver and skeletal muscle tissues.
文摘Accurate prediction of unsteady separated turbulent flows remains one of the toughest tasks and a practi cal challenge for turbulence modeling. In this paper, a 2D flow past a circular cylinder at Reynolds number 3,900 is numerically investigated by using the technique of unsteady RANS （URANS）. Some typical linear and nonlinear eddy viscosity turbulence models （LEVM and NLEVM） and a quadratic explicit algebraic stress model （EASM） are evaluated. Numerical results have shown that a high-performance cubic NLEVM, such as CLS, are superior to the others in simulating turbulent separated flows with unsteady vortex shedding.
基金The project supported by the National Natural Science Foundation of China
文摘This paper presents a separated law of hardening in plasticity with strain gradient effects. The value of the length parameter l contained in this model was estimated from the experimental data for copper.
文摘In this paper, an oscillation frequency equation for a pizoelectric sensor with two separated-electrodes is theoretically derived and experimentally verified. The correlatione of the oscillation frequency and the liquid properties are investigated.
