AlphaPanda(AlphaFold2[1]inspired protein-specific antibody design in a diffusional manner)is an advanced algorithm for designing complementary determining regions(CDRs)of the antibody targeted the specific epitope,com...AlphaPanda(AlphaFold2[1]inspired protein-specific antibody design in a diffusional manner)is an advanced algorithm for designing complementary determining regions(CDRs)of the antibody targeted the specific epitope,combining transformer[2]models,3DCNN[3],and diffusion[4]generative models.展开更多
Degenerative disc disease is the most common cause of low back pain. Intervertebral disc abnormalities are commonly evaluated by magnetic resonance imaging (MRI), and Pfirrmann’s system involves the use of T2-weighte...Degenerative disc disease is the most common cause of low back pain. Intervertebral disc abnormalities are commonly evaluated by magnetic resonance imaging (MRI), and Pfirrmann’s system involves the use of T2-weighted images (T2WI) to classify disc degeneration. However, as this classification is based on visual evaluation, it is not possible to quantify degeneration using this method. The present study was performed to establish an MRI-based intervertebral disc classification system using diffusional kurtosis imaging (DKI), to quantify intervertebral disc water content according to the Pfirrmann classification. Sagittal mean diffusional kurtosis (MK) mapping was performed for the L3/4, L4/5, and L5/S1 intervertebral discs in 32 patients (15 female, 17 male;age range, 24 - 82 years;mean age, 57.7 years). The degree of disc degeneration was assessed in the midsagittal section on T2WI according to the Pfirrmann classification (grade I - V). The relationships between MK values, which are correlated with intervertebral disc composition changes, and grade of degeneration determined using the Pfirrmann classification were analyzed. The MK values tended to decrease with increasing grade of degeneration, and differed significantly between grades I and IV, but not between grade IV and V (P < 0.05, Mann-Whitney U test). DKI is an effective means of detecting the early stages of disc degeneration. Therefore, DKI may be a useful diagnostic tool for quantitative assessment of intervertebral disc degeneration.展开更多
The solid-phase transformations of metal materials under high magnetic fields are an important topic in research on the electromagnetic processing of materials.Progress in research on the diffusional phase transformat...The solid-phase transformations of metal materials under high magnetic fields are an important topic in research on the electromagnetic processing of materials.Progress in research on the diffusional phase transformations of Fe–C alloys under high magnetic fields is reviewed.The effects of high magnetic fields on the microstructural evolution in diffusional phase transformations in Fe–C alloys are discussed.The kinetics of ferrite transformations,pearlite transformations,and the precipitation of carbides under high magnetic fields are reviewed in terms of the thermodynamics of phase transformations and the diffusion behavior of carbon atoms.Finally,future trends in research on diffusional phase transformations of Fe–C alloys under high magnetic fields are discussed.展开更多
The microstructure,diffusional and mechanical bonding behavior and microhardness distribution of laminated composites fabricated by ECAP process were investigated.Al?Cu and Cu?Ni laminated composites were produced by ...The microstructure,diffusional and mechanical bonding behavior and microhardness distribution of laminated composites fabricated by ECAP process were investigated.Al?Cu and Cu?Ni laminated composites were produced by ECAP process up to4passes at room temperature and high temperature(300°C).The results of microstructure characterization by SEM and shear strength test revealed that the joints between the layers of4-pass ECAPed samples were considerably stronger than those of1-pass ECAPed samples due to tolerating higher values of plastic deformations during ECAP.Furthermore,shear strength data showed that increasing ECAP temperature caused a notable increase in shear strength of the specimens.The reason lies in the formation of diffusional joint between the interface of both Al/Cu and Cu/Ni layers at high temperature.The shear bonding strength of ECAPed Cu/Ni/Cu composite at high temperature was remarkably higher than that of ECAPed Cu/Al/Cu composite.展开更多
In this paper, we experimentally investigate the dark diffusional enhancement of the optimized multiplexed grating in the phenanthrenequinone doped poly （methyl methacrylate） （PQ-PMMA） photopolymer. The possibilit...In this paper, we experimentally investigate the dark diffusional enhancement of the optimized multiplexed grating in the phenanthrenequinone doped poly （methyl methacrylate） （PQ-PMMA） photopolymer. The possibility of improving the holographic characteristics of the material through the dark enhancement is demonstrated. The optimal preillumination exposure and the optimal time interval between exposures are extracted to obtain the optimized diffraction efficiency, and their values are 3.4×103 mJ/cm2 and 2 min, respectively. The dark enhancement of the multiplexed grating is presented as an effective method to improve the response region and the dynamic range and to prevent saturation of the material. The dependence of the phenanthrenequinone concentration on the increment of the refractive index modulation is quantitatively studied, which provides a significant basis for improving the homogeneity in the multiplexed gratings using a quantitative strategy. Finally, a simple experimental procedure using the dark enhancement is introduced to improve the homogeneity of the diffraction efficiency and to avoid the complex schedule exposure.展开更多
Oxygen consumption is a fundamental component of metabolic networks, mitochondrial function, and global carbon cycling. To date there is no method available that allows for replicate measurements on attached and unatt...Oxygen consumption is a fundamental component of metabolic networks, mitochondrial function, and global carbon cycling. To date there is no method available that allows for replicate measurements on attached and unattached biological samples without compensation for extraneous oxygen leaking into the system. Here we present the Respiratory Detection System, which is compatible with virtually any biological sample. The RDS can be used to measure oxygen uptake in microliter-scale volumes with a reversibly sealed sample chamber, which contains a porphyrin-based oxygen sensor. With the RDS, one can maintain a diffusional seal for up to three hours, allowing for the direct measurement of respiratory function of samples with fast or slow metabolic rates. The ability to easily measure oxygen uptake in small volumes with small populations or dilute samples has implications in cell biology, environmental biology, and clinical diagnostics.展开更多
An exact solution has been obtained for the release kinetics of a solute from a cylindrical non-erodible polymeric matrix into a finite external volume when the initial solute loading is greater than the solubility li...An exact solution has been obtained for the release kinetics of a solute from a cylindrical non-erodible polymeric matrix into a finite external volume when the initial solute loading is greater than the solubility limit in the matrix. The moving boundary solution is derived based on the combination of variable method. The formulas of the moving boundary and the fractional solute release are given. The moving boundary and the fractional solute release profiles have been calculated at various solute loading levels and different external volumes. The obtained results show that as the external fluid volume increases, the fractional release at any time and the maximum fractional release increase. In addition, for a given external volume, as initial drug loading increases, the fractional release at any time decreases.展开更多
Brain development is one of the most fascinating subjects in the field of biological sciences. Nonetheless, our scientific commu- nity still faces challenges in trying to understand the concepts that define the underl...Brain development is one of the most fascinating subjects in the field of biological sciences. Nonetheless, our scientific commu- nity still faces challenges in trying to understand the concepts that define the underlying mechanisms of neural tissue devel- opment. After all, it is a very complex subject to grasp and many of the processes that take place during central nervous system maturation are yet to be ascertained. Despite this challenge, we have come to recognize that understanding the natural course of normal brain tissue development on both microscopic and macroscopic scales is the key to deciphering the mechanisms through which these neural networks also heal and regenerate. Realizing this concept, my good friend and colleague, Dr. Sar- ah Milla, and I decided to take on a human study to investigate brain maturation using non-invasive imaging techniques in the pediatric population at New York University （NYU） School of Medicine （Paydar et al., 2013）. Our research subjects included 59 normal infants with an age spectrum ranging from birth to approximately 5 years of age, when the brain is in its most active stage of development. We implemented a Magnetic Resonance Imaging （MRI） diffusion technique called Diffusional Kurtosis Imaging （DKI） to investigate the microstructural changes that occur in both the white matter （WM） and gray matter （GM） in the developing brain.展开更多
Density functional theory calculations in conjunction with the climbing images nudged elastic band method are conducted to study the diffusion phenomena of the Ni-based single crystal superalloys.We focus our attentio...Density functional theory calculations in conjunction with the climbing images nudged elastic band method are conducted to study the diffusion phenomena of the Ni-based single crystal superalloys.We focus our attention on the diffusion processes of the Ni and Al atoms in the γ and γ ’ phases along the direction perpendicular to the interface.The diffusion mechanisms and the expressions of the diffusion coefficients are presented.The vacancy formation energies,the migration energies,and the activation energies for the diffusing Ni and Al atoms are estimated,and these quantities display the expected and clear transition zones in the vicinity of the interface of about 3–7（002） layers.The local density-of-states profiles of atoms in each（002） layer in the γ and γ ’ phases and the partial density-of-states curves of Re and some of its nearest-neighbor atoms are also presented to explore the electronic effect of the diffusion behavior.展开更多
Separation was reported by Dunn, Hankins and Ghowsi for the case that ions incapillary electrophoresis move opposite to electroosmosis and ions move faster than flow finally they get separated and reach the detector. ...Separation was reported by Dunn, Hankins and Ghowsi for the case that ions incapillary electrophoresis move opposite to electroosmosis and ions move faster than flow finally they get separated and reach the detector. Similar mode for electrokinetic chromatography is reported for p-xylene and toluene separation, which is called reverse direction MECC （micellar electrokinetic capillary chromatography）. The effect of injection time on separation in reverse direction micellar electrokinetic capillary chromatography is investigated. In this study, hydrostatic and diffusion injection were studied.展开更多
One of the great advantages of electrospun fibers is the large tridimensional area produced, capable of storing any type of material. The aim of our investigation is to study the electrospinning technique to produce p...One of the great advantages of electrospun fibers is the large tridimensional area produced, capable of storing any type of material. The aim of our investigation is to study the electrospinning technique to produce polymer membranes for drug delivery applications, given their large surface area and ability to transport a bioactive compound. A mathematical modeling of the delivery system kinetics was also studied to find the mechanism that controls the releasing process. Results showed that electrospinning could provide regular and smooth membranes suitable for drug delivery processes. The mathematical modeling also proved that thicker PLLA membranes exhibited a Fickian diffusion behavior during the drug transport, presenting better control in drug delivery processes.展开更多
This paper is devoted to the study of the dynamical behavior and harvesting problem of an exploited population with diffusional migration, for which a protective patch is established. We examine the effects of protect...This paper is devoted to the study of the dynamical behavior and harvesting problem of an exploited population with diffusional migration, for which a protective patch is established. We examine the effects of protective patch and harvest on the population resources and conclude that the protective patch is effective for the conservation of population resources and ecological environment, though in some cases the extinction can not be eliminated. The dangerous region, the parameters domains and the typical bifurcation curves of stability of steady states for the considered system are determined. The optimal harvest policy for the considered population is made also. The explicit expressions are obtained for the optimal harvesting effort, the maximum sustainable yield and the corre- sponding population density. Our results provide a theoretical evidence for the practical management of biological resources.展开更多
Cerebral small vessel disease encompasses a group of neurological disorders characterized by injury to small blood vessels,often leading to stroke and dementia.Due to its diverse etiologies and complex pathological me...Cerebral small vessel disease encompasses a group of neurological disorders characterized by injury to small blood vessels,often leading to stroke and dementia.Due to its diverse etiologies and complex pathological mechanisms,preventing and treating cerebral small vessel vasculopathy is challenging.Recent studies have shown that the glymphatic system plays a crucial role in interstitial solute clearance and the maintenance of brain homeostasis.Increasing evidence also suggests that dysfunction in glymphatic clearance is a key factor in the progression of cerebral small vessel disease.This review begins with a comprehensive introduction to the structure,function,and driving factors of the glymphatic system,highlighting its essential role in brain waste clearance.Afterwards,cerebral small vessel disease was reviewed from the perspective of the glymphatic system,after which the mechanisms underlying their correlation were summarized.Glymphatic dysfunction may lead to the accumulation of metabolic waste in the brain,thereby exacerbating the pathological processes associated with cerebral small vessel disease.The review also discussed the direct evidence of glymphatic dysfunction in patients and animal models exhibiting two subtypes of cerebral small vessel disease:arteriolosclerosis-related cerebral small vessel disease and amyloid-related cerebral small vessel disease.Diffusion tensor image analysis along the perivascular space is an important non-invasive tool for assessing the clearance function of the glymphatic system.However,the effectiveness of its parameters needs to be enhanced.Among various nervous system diseases,including cerebral small vessel disease,glymphatic failure may be a common final pathway toward dementia.Overall,this review summarizes prevention and treatment strategies that target glymphatic drainage and will offer valuable insight for developing novel treatments for cerebral small vessel disease.展开更多
Fine-grained nuclear graphite is a key material in high-temperature gas-cooled reactors(HTGRs).During air ingress accidents,core graphite components undergo severe oxidation,threatening structural integrity.Therefore,...Fine-grained nuclear graphite is a key material in high-temperature gas-cooled reactors(HTGRs).During air ingress accidents,core graphite components undergo severe oxidation,threatening structural integrity.Therefore,understanding the oxidation behavior of nuclear graphite is essential for reactor safety.The influence of oxidation involves multiple factors,including temperature,sample size,oxidant,impurities,filler type and size,etc.The size of the filler particles plays a crucial role in this study.Five ultrafine-and superfine-grained nuclear graphite samples(5.9-34.4μm)are manufactured using identical raw materials and manufacturing processes.Isothermal oxidation tests conducted at 650℃-750℃ are used to study the oxidation behavior.Additionally,comprehensive characterization is performed to analyze the crystal structure,surface morphology,and nanoscale to microscale pore structure of the samples.Results indicate that oxidation behavior cannot be predicted solely based on filler grain size.Reactive site concentration,characterized by active surface area,dominates the chemical reaction kinetics,whereas pore tortuosity,quantified by the structural parameterΨ,plays a key role in regulating oxidant diffusion.These findings clarify the dual role of microstructure in oxidation mechanisms and establish a theoretical and experimental basis for the design of high-performance nuclear graphite capable of long-term service in high-temperature gas-cooled reactors.展开更多
Hard carbon(HC)in sodium-ion batteries is searched by numerous investigations,which can offer the excellent performance of reversible Na^(+)insertion and extraction.The covalent heteroatom doping in HC is recently wor...Hard carbon(HC)in sodium-ion batteries is searched by numerous investigations,which can offer the excellent performance of reversible Na^(+)insertion and extraction.The covalent heteroatom doping in HC is recently worth concentrating,which can dilate the interlayer spacing of graphite to adjust the electrochemical storage performance in carbon anodes.However,the reported doping strategies of the modified HC have only resulted in limited improvement,especially unobvious effects on tuning porous structure.In this study,tannin extract and K_(2)SO_(4) are respectively utilized as carbon source and sulfur source for the fabrication of HC,in which K_(2)SO_(4) can contribute to the heteroatom doping,and the pore forming as well.The tannin-derived sulfur-doped carbon anode shows the excellent cycle stability,achieving a high reversible capacity of 520.5 mAh/g at a current density of 100 mA/g.Even after 500 cycles at a current density of 3 A/g,a high specific capacity of 236.7 mAh/g and a capacity retention rate of 92.6%can be reserved.Compared with the initial carbon,the adsorption energy of Na^(+)is multifold times higher,whereas Na^(+)diffusion energy barriers manyfold decrease.Moreover,the full battery assembled with Na_(3)V_(2)(PO_(4))_(3)/tannin-based HC demonstrates a stable cycling performance.This work can manifest the potentiality of the tannin-based electrode as anode for a high-performance sodium-ion batteries(SIBs),which could especially offer an explanation of Na^(+)storage and solid-electrolyte interface(SEI)stability to the electrochemical performance.展开更多
The fast solution of linear equations has always been one of the hot spots in scientific computing.A kind of the diagonal matrix splitting iteration methods are provided,which is different from the classical matrix sp...The fast solution of linear equations has always been one of the hot spots in scientific computing.A kind of the diagonal matrix splitting iteration methods are provided,which is different from the classical matrix splitting methods.Taking the decomposition of the diagonal elements for coefficient matrix as the key point,some new preconditioners are constructed.Taking the tri-diagonal coefficient matrix as an example,the convergence domains and optimal relaxation factor of the new method are analyzed theoretically.The presented new iteration methods are applied to solve linear algebraic equations,even 2D and 3D diffusion problems with the fully implicit discretization.The results of numerical experiments are matched with the theoretical analysis,and show that the iteration numbers are reduced greatly.The superiorities of presented iteration methods exceed some classical iteration methods dramatically.展开更多
基金supported by the Key Project of International Cooperation of Qilu University of Technology(Grant No.:QLUTGJHZ2018008)Shandong Provincial Natural Science Foundation Committee,China(Grant No.:ZR2016HB54)Shandong Provincial Key Laboratory of Microbial Engineering(SME).
文摘AlphaPanda(AlphaFold2[1]inspired protein-specific antibody design in a diffusional manner)is an advanced algorithm for designing complementary determining regions(CDRs)of the antibody targeted the specific epitope,combining transformer[2]models,3DCNN[3],and diffusion[4]generative models.
文摘Degenerative disc disease is the most common cause of low back pain. Intervertebral disc abnormalities are commonly evaluated by magnetic resonance imaging (MRI), and Pfirrmann’s system involves the use of T2-weighted images (T2WI) to classify disc degeneration. However, as this classification is based on visual evaluation, it is not possible to quantify degeneration using this method. The present study was performed to establish an MRI-based intervertebral disc classification system using diffusional kurtosis imaging (DKI), to quantify intervertebral disc water content according to the Pfirrmann classification. Sagittal mean diffusional kurtosis (MK) mapping was performed for the L3/4, L4/5, and L5/S1 intervertebral discs in 32 patients (15 female, 17 male;age range, 24 - 82 years;mean age, 57.7 years). The degree of disc degeneration was assessed in the midsagittal section on T2WI according to the Pfirrmann classification (grade I - V). The relationships between MK values, which are correlated with intervertebral disc composition changes, and grade of degeneration determined using the Pfirrmann classification were analyzed. The MK values tended to decrease with increasing grade of degeneration, and differed significantly between grades I and IV, but not between grade IV and V (P < 0.05, Mann-Whitney U test). DKI is an effective means of detecting the early stages of disc degeneration. Therefore, DKI may be a useful diagnostic tool for quantitative assessment of intervertebral disc degeneration.
基金supported by the National Natural Science Foundation of China(Grant No.51690162)Liaoning Revitalization Talents Program(Grant No.XLYC1908002)Fundamental Research Funds for the Central Universities(Grant No.N180912004).
文摘The solid-phase transformations of metal materials under high magnetic fields are an important topic in research on the electromagnetic processing of materials.Progress in research on the diffusional phase transformations of Fe–C alloys under high magnetic fields is reviewed.The effects of high magnetic fields on the microstructural evolution in diffusional phase transformations in Fe–C alloys are discussed.The kinetics of ferrite transformations,pearlite transformations,and the precipitation of carbides under high magnetic fields are reviewed in terms of the thermodynamics of phase transformations and the diffusion behavior of carbon atoms.Finally,future trends in research on diffusional phase transformations of Fe–C alloys under high magnetic fields are discussed.
文摘The microstructure,diffusional and mechanical bonding behavior and microhardness distribution of laminated composites fabricated by ECAP process were investigated.Al?Cu and Cu?Ni laminated composites were produced by ECAP process up to4passes at room temperature and high temperature(300°C).The results of microstructure characterization by SEM and shear strength test revealed that the joints between the layers of4-pass ECAPed samples were considerably stronger than those of1-pass ECAPed samples due to tolerating higher values of plastic deformations during ECAP.Furthermore,shear strength data showed that increasing ECAP temperature caused a notable increase in shear strength of the specimens.The reason lies in the formation of diffusional joint between the interface of both Al/Cu and Cu/Ni layers at high temperature.The shear bonding strength of ECAPed Cu/Ni/Cu composite at high temperature was remarkably higher than that of ECAPed Cu/Al/Cu composite.
基金supported by the National Basic Research Program of China(Grant No.2007CB3070001)the Fundamental Research Funds for the Central Universities,China(Grant No.HIT.NSRIF.2010009)+1 种基金the Program of Excellent Team in Harbin Institute of Technology,Chinathe Research Startup Foundation of Civil Aviation University of China(Grant No.2010QN03X)
文摘In this paper, we experimentally investigate the dark diffusional enhancement of the optimized multiplexed grating in the phenanthrenequinone doped poly （methyl methacrylate） （PQ-PMMA） photopolymer. The possibility of improving the holographic characteristics of the material through the dark enhancement is demonstrated. The optimal preillumination exposure and the optimal time interval between exposures are extracted to obtain the optimized diffraction efficiency, and their values are 3.4×103 mJ/cm2 and 2 min, respectively. The dark enhancement of the multiplexed grating is presented as an effective method to improve the response region and the dynamic range and to prevent saturation of the material. The dependence of the phenanthrenequinone concentration on the increment of the refractive index modulation is quantitatively studied, which provides a significant basis for improving the homogeneity in the multiplexed gratings using a quantitative strategy. Finally, a simple experimental procedure using the dark enhancement is introduced to improve the homogeneity of the diffraction efficiency and to avoid the complex schedule exposure.
文摘Oxygen consumption is a fundamental component of metabolic networks, mitochondrial function, and global carbon cycling. To date there is no method available that allows for replicate measurements on attached and unattached biological samples without compensation for extraneous oxygen leaking into the system. Here we present the Respiratory Detection System, which is compatible with virtually any biological sample. The RDS can be used to measure oxygen uptake in microliter-scale volumes with a reversibly sealed sample chamber, which contains a porphyrin-based oxygen sensor. With the RDS, one can maintain a diffusional seal for up to three hours, allowing for the direct measurement of respiratory function of samples with fast or slow metabolic rates. The ability to easily measure oxygen uptake in small volumes with small populations or dilute samples has implications in cell biology, environmental biology, and clinical diagnostics.
文摘An exact solution has been obtained for the release kinetics of a solute from a cylindrical non-erodible polymeric matrix into a finite external volume when the initial solute loading is greater than the solubility limit in the matrix. The moving boundary solution is derived based on the combination of variable method. The formulas of the moving boundary and the fractional solute release are given. The moving boundary and the fractional solute release profiles have been calculated at various solute loading levels and different external volumes. The obtained results show that as the external fluid volume increases, the fractional release at any time and the maximum fractional release increase. In addition, for a given external volume, as initial drug loading increases, the fractional release at any time decreases.
文摘Brain development is one of the most fascinating subjects in the field of biological sciences. Nonetheless, our scientific commu- nity still faces challenges in trying to understand the concepts that define the underlying mechanisms of neural tissue devel- opment. After all, it is a very complex subject to grasp and many of the processes that take place during central nervous system maturation are yet to be ascertained. Despite this challenge, we have come to recognize that understanding the natural course of normal brain tissue development on both microscopic and macroscopic scales is the key to deciphering the mechanisms through which these neural networks also heal and regenerate. Realizing this concept, my good friend and colleague, Dr. Sar- ah Milla, and I decided to take on a human study to investigate brain maturation using non-invasive imaging techniques in the pediatric population at New York University （NYU） School of Medicine （Paydar et al., 2013）. Our research subjects included 59 normal infants with an age spectrum ranging from birth to approximately 5 years of age, when the brain is in its most active stage of development. We implemented a Magnetic Resonance Imaging （MRI） diffusion technique called Diffusional Kurtosis Imaging （DKI） to investigate the microstructural changes that occur in both the white matter （WM） and gray matter （GM） in the developing brain.
基金Project supported by National Basic Research Program of China(Grant No.2011CB606402)the National Natural Science Foundation of China(Grant No.51071091)
文摘Density functional theory calculations in conjunction with the climbing images nudged elastic band method are conducted to study the diffusion phenomena of the Ni-based single crystal superalloys.We focus our attention on the diffusion processes of the Ni and Al atoms in the γ and γ ’ phases along the direction perpendicular to the interface.The diffusion mechanisms and the expressions of the diffusion coefficients are presented.The vacancy formation energies,the migration energies,and the activation energies for the diffusing Ni and Al atoms are estimated,and these quantities display the expected and clear transition zones in the vicinity of the interface of about 3–7（002） layers.The local density-of-states profiles of atoms in each（002） layer in the γ and γ ’ phases and the partial density-of-states curves of Re and some of its nearest-neighbor atoms are also presented to explore the electronic effect of the diffusion behavior.
文摘Separation was reported by Dunn, Hankins and Ghowsi for the case that ions incapillary electrophoresis move opposite to electroosmosis and ions move faster than flow finally they get separated and reach the detector. Similar mode for electrokinetic chromatography is reported for p-xylene and toluene separation, which is called reverse direction MECC （micellar electrokinetic capillary chromatography）. The effect of injection time on separation in reverse direction micellar electrokinetic capillary chromatography is investigated. In this study, hydrostatic and diffusion injection were studied.
文摘One of the great advantages of electrospun fibers is the large tridimensional area produced, capable of storing any type of material. The aim of our investigation is to study the electrospinning technique to produce polymer membranes for drug delivery applications, given their large surface area and ability to transport a bioactive compound. A mathematical modeling of the delivery system kinetics was also studied to find the mechanism that controls the releasing process. Results showed that electrospinning could provide regular and smooth membranes suitable for drug delivery processes. The mathematical modeling also proved that thicker PLLA membranes exhibited a Fickian diffusion behavior during the drug transport, presenting better control in drug delivery processes.
基金This research is supported by the National Natural Science Foundation of China(No. 19871012).
文摘This paper is devoted to the study of the dynamical behavior and harvesting problem of an exploited population with diffusional migration, for which a protective patch is established. We examine the effects of protective patch and harvest on the population resources and conclude that the protective patch is effective for the conservation of population resources and ecological environment, though in some cases the extinction can not be eliminated. The dangerous region, the parameters domains and the typical bifurcation curves of stability of steady states for the considered system are determined. The optimal harvest policy for the considered population is made also. The explicit expressions are obtained for the optimal harvesting effort, the maximum sustainable yield and the corre- sponding population density. Our results provide a theoretical evidence for the practical management of biological resources.
基金supported by the National Natural Science Foundation of China,No.82274304(to YH)the Major Clinical Study Projects of Shanghai Shenkang Hospital Development Center,No.SHDC2020CR2046B(to YH)Shanghai Municipal Health Commission Talent Plan,No.2022LJ010(to YH).
文摘Cerebral small vessel disease encompasses a group of neurological disorders characterized by injury to small blood vessels,often leading to stroke and dementia.Due to its diverse etiologies and complex pathological mechanisms,preventing and treating cerebral small vessel vasculopathy is challenging.Recent studies have shown that the glymphatic system plays a crucial role in interstitial solute clearance and the maintenance of brain homeostasis.Increasing evidence also suggests that dysfunction in glymphatic clearance is a key factor in the progression of cerebral small vessel disease.This review begins with a comprehensive introduction to the structure,function,and driving factors of the glymphatic system,highlighting its essential role in brain waste clearance.Afterwards,cerebral small vessel disease was reviewed from the perspective of the glymphatic system,after which the mechanisms underlying their correlation were summarized.Glymphatic dysfunction may lead to the accumulation of metabolic waste in the brain,thereby exacerbating the pathological processes associated with cerebral small vessel disease.The review also discussed the direct evidence of glymphatic dysfunction in patients and animal models exhibiting two subtypes of cerebral small vessel disease:arteriolosclerosis-related cerebral small vessel disease and amyloid-related cerebral small vessel disease.Diffusion tensor image analysis along the perivascular space is an important non-invasive tool for assessing the clearance function of the glymphatic system.However,the effectiveness of its parameters needs to be enhanced.Among various nervous system diseases,including cerebral small vessel disease,glymphatic failure may be a common final pathway toward dementia.Overall,this review summarizes prevention and treatment strategies that target glymphatic drainage and will offer valuable insight for developing novel treatments for cerebral small vessel disease.
基金supported by the National Key Research and Development Program of China(2024YFA1612900)the National Natural Science Foundation of China(Grant No.52103365 and No.12375270)the Guangdong Innovative and Entrepreneurial Research Team Program,China(Grant No.2021ZT09L227).
文摘Fine-grained nuclear graphite is a key material in high-temperature gas-cooled reactors(HTGRs).During air ingress accidents,core graphite components undergo severe oxidation,threatening structural integrity.Therefore,understanding the oxidation behavior of nuclear graphite is essential for reactor safety.The influence of oxidation involves multiple factors,including temperature,sample size,oxidant,impurities,filler type and size,etc.The size of the filler particles plays a crucial role in this study.Five ultrafine-and superfine-grained nuclear graphite samples(5.9-34.4μm)are manufactured using identical raw materials and manufacturing processes.Isothermal oxidation tests conducted at 650℃-750℃ are used to study the oxidation behavior.Additionally,comprehensive characterization is performed to analyze the crystal structure,surface morphology,and nanoscale to microscale pore structure of the samples.Results indicate that oxidation behavior cannot be predicted solely based on filler grain size.Reactive site concentration,characterized by active surface area,dominates the chemical reaction kinetics,whereas pore tortuosity,quantified by the structural parameterΨ,plays a key role in regulating oxidant diffusion.These findings clarify the dual role of microstructure in oxidation mechanisms and establish a theoretical and experimental basis for the design of high-performance nuclear graphite capable of long-term service in high-temperature gas-cooled reactors.
基金supported by National Natural Science Foundation of China(Nos.32271791,32171709 and 22475053)Hunan Provincial Natural Science Foundation of China(No.2024JJ7643)Natural Science Foundation of Shanghai(No.22ZR1404100).
文摘Hard carbon(HC)in sodium-ion batteries is searched by numerous investigations,which can offer the excellent performance of reversible Na^(+)insertion and extraction.The covalent heteroatom doping in HC is recently worth concentrating,which can dilate the interlayer spacing of graphite to adjust the electrochemical storage performance in carbon anodes.However,the reported doping strategies of the modified HC have only resulted in limited improvement,especially unobvious effects on tuning porous structure.In this study,tannin extract and K_(2)SO_(4) are respectively utilized as carbon source and sulfur source for the fabrication of HC,in which K_(2)SO_(4) can contribute to the heteroatom doping,and the pore forming as well.The tannin-derived sulfur-doped carbon anode shows the excellent cycle stability,achieving a high reversible capacity of 520.5 mAh/g at a current density of 100 mA/g.Even after 500 cycles at a current density of 3 A/g,a high specific capacity of 236.7 mAh/g and a capacity retention rate of 92.6%can be reserved.Compared with the initial carbon,the adsorption energy of Na^(+)is multifold times higher,whereas Na^(+)diffusion energy barriers manyfold decrease.Moreover,the full battery assembled with Na_(3)V_(2)(PO_(4))_(3)/tannin-based HC demonstrates a stable cycling performance.This work can manifest the potentiality of the tannin-based electrode as anode for a high-performance sodium-ion batteries(SIBs),which could especially offer an explanation of Na^(+)storage and solid-electrolyte interface(SEI)stability to the electrochemical performance.
基金The National Natural Science Foundations of China (12202219)the Natural Science Foundations of Ningxia (2024AAC02009, 2023AAC05001)the Ningxia Youth Top Talents Training Project。
文摘The fast solution of linear equations has always been one of the hot spots in scientific computing.A kind of the diagonal matrix splitting iteration methods are provided,which is different from the classical matrix splitting methods.Taking the decomposition of the diagonal elements for coefficient matrix as the key point,some new preconditioners are constructed.Taking the tri-diagonal coefficient matrix as an example,the convergence domains and optimal relaxation factor of the new method are analyzed theoretically.The presented new iteration methods are applied to solve linear algebraic equations,even 2D and 3D diffusion problems with the fully implicit discretization.The results of numerical experiments are matched with the theoretical analysis,and show that the iteration numbers are reduced greatly.The superiorities of presented iteration methods exceed some classical iteration methods dramatically.
