The bubble growth and detachment behavior in the bottom blowing process were investigated. Four multi-hole nozzle configurations with different opening ratios were assessed experimentally using high-speed photography ...The bubble growth and detachment behavior in the bottom blowing process were investigated. Four multi-hole nozzle configurations with different opening ratios were assessed experimentally using high-speed photography and digital image processing. For these configurations, the experiments reveal that the bubble growth consists of a petal-like stage, an expansion stage and a detachment stage. The petal-like shape is qualitatively described through the captured images, while the non-spherical bubbles are analyzed by the aspect ratio. The bubble size at the detachment is quantified by the maximum caliper distance and the bubble equivalent diameter. Considering the dependence on the opening ratio, different prediction models for the ratio of maximum caliper distance to hydraulic diameter of the nozzle outlet and the dimensionless bubble diameter are established. The comparative analysis results show that the proposed prediction model can accurately predict the bubble detachment size under the condition of multi-hole nozzles.展开更多
Italian ray grass and oat are two grass species characterized by their ability to adjust tropical climate conditions. This study proposed to assess forage productivities to allow an appropriate mowing period determina...Italian ray grass and oat are two grass species characterized by their ability to adjust tropical climate conditions. This study proposed to assess forage productivities to allow an appropriate mowing period determination in their use as dairy female feed in Madagascar. A test on small plots has been set up in the southern part of the capital city Antananarivo during one dry period (4 months). Live observations followed by laboratory proximate analyses have been performed for forage productivity and feeding value determination. Cultivated on tanety (hill), irrigated in counter season, results show that: (I) oat higher height (H = 96.7 cm) than Italian ray grass (H= 69.4 cm) at 99 days of age; (2) similar biomass productivity; (3) dry matter yields significantly different (p = 0.05); (4) certain similarity between dry matter yields and FMU (fodder milk unit) score evolution; (5) leafy stage of Italian ray grasses at 99 days of age; (6) mid-flowering stage for oats during the same period. Cell wall content, crude fiber and dry matter contents increased with age (p = 0.05). Crude proteins and minerals evolved in opposite directions. Gross energy content did not present precise variation with age. This study allowed that for an acceptable quantitative and qualitative production during dry seasons, good mowing period for Italian ray grass could start at 76 days age, while oat could start being harvested at 68 days.展开更多
The paper addresses the formulation of rate equations, via objective time derivatives, within continuum physics. The concept of objectivity is reviewed and distinction is made with material frame-indifference whose me...The paper addresses the formulation of rate equations, via objective time derivatives, within continuum physics. The concept of objectivity is reviewed and distinction is made with material frame-indifference whose meaning is restricted to the invariance of the balance equations relative to Galilean frames. Objective time derivatives are defined to leave the tensor character of the appropriate field invariant within the set of Euclidean frames. Rate equations are required to involve objective time derivatives and to be consistent with the second law of thermodynamics. Here the general structure of objective time derivatives is established and the known derivatives of the physical literature are shown to be particular cases. Next, to fix ideas, a rate equation is considered for the model of heat conduction via a generalization of the Maxwell-Cattaneo equation with higher-order gradients as in the Guyer-Krumhansl equation. The thermodynamic restrictions are investigated and the expected effects, of the selected derivative of the heat flux, on the stress tensor are derived.展开更多
In thermoacoustic system,the characteristic of complex compliance of a regenerator has a great influence on energy stored and dissipation of the whole engine.In order to investigate the performance of regenerators wit...In thermoacoustic system,the characteristic of complex compliance of a regenerator has a great influence on energy stored and dissipation of the whole engine.In order to investigate the performance of regenerators with different matrix geometries and materials coupled with different acoustic systems,an experimental measurement and analysis method was presented.By measuring the resonant frequency,the complex compliance and quality factor of five kinds of matrix were experimentally analyzed respectively in the system of loudspeaker-driven thermoacoustic resonator(TAR)with different lengths.The experimental results show that the real part of complex compliance of the regenerator with pin-array has a maximum value among the measured matrixes and its quality factor is the largest(28.222)with the least dissipation factor of 0.035 4.So the pin-array matrix is testified to behave more excellently on the energy conversion than other matrixes.Compared with other factors the complex compliance of a regenerator contributes more to the performance of a thermoacoustic system.展开更多
An essential step for the realization of free-form surface structures is to create an efficient structural gird that satisfies not only the architectural aesthetics,but also the structural performance.Employing the ma...An essential step for the realization of free-form surface structures is to create an efficient structural gird that satisfies not only the architectural aesthetics,but also the structural performance.Employing the main stress trajectories as the representation of force flows on a free-form surface,an automatic grid generation approach is proposed for the architectural design.The algorithm automatically plots the main stress trajectories on a 3D free-form surface,and adopts a modified advancing front meshing technique to generate the structural grid.Based on the proposed algorithm,an automatic grid generator named "St-Surmesh" is developed for the practical architectural design of free-form surface structure.The surface geometry of one of the Sun Valleys in Expo Axis for the Expo Shanghai 2010 is selected as a numerical example for validating the proposed approach.Comparative studies are performed to demonstrate how different structural grids affect the design of a free-form surface structure.展开更多
Arthritis, most notably rheumatoid arthritis, can destroy the surfaces of the bones; the ideal solution for this is T JR (total joint replacement), which would restore joint functionality, maintain correct aesthetic...Arthritis, most notably rheumatoid arthritis, can destroy the surfaces of the bones; the ideal solution for this is T JR (total joint replacement), which would restore joint functionality, maintain correct aesthetics and eradicate pain for the patient. Current metacarpophalangeal TJR do not provide the normal biomechanical range of motion and functionality. The proposed design attempts to correct this through the use of design geometry and functional anatomy. Numerical analysis is used in conjunction with computational solid modeling to compare a one-piece silicone implant with the proposed T JR. Peak stresses during flexion for the proposed design did not exceed 1.2 MPa, where as soft implants approach 100 MPa to 1,000 MPa for peak stress values. The proposed design, due to high stress tolerances with low deformation, along with functionality and biomechanics, seems to be an appropriate replacement for one-piece silicone implant.展开更多
Today's math education basic syllabus gives an ever increasing emphasis to Geometry and Patterns. Curricula also advocate an approach that allows student to understand the concepts involved supported by dynamical com...Today's math education basic syllabus gives an ever increasing emphasis to Geometry and Patterns. Curricula also advocate an approach that allows student to understand the concepts involved supported by dynamical computer tools. However, there is not much research work joining these paradigms. Therefore, a case study was developed, with 9th grade students (14-15 years old), to evaluate the impact of a creative approach to isometries and symmetries-friezes, rosaceas (rosettes) and wallpapers-centered in patterns (reproduction, continuation, completion, description and creation) and using Geometer's Sketchpad software to solve, mainly in pairs, and discuss, with the whole class, the challenging tasks proposed, involving the formulation of hypothesis, argumentation and justification of the reasoning. The statistical analysis of the quantifiable data and content analysis of the qualitative data, collecting trough enquiry, direct observation and documental analysis (involving questionnaires, field notes, logbook, pre-tests and post-test, other works of the students including those computer related, and internal documents of the school) enable to conclude positively regarding the main research question underlying the study. In fact, it led to the conclusion that the teaching strategy implemented has contributed to deepen the student's knowledge and skills on geometry, mathematical communication and autonomy as well as to develop a closer relation with the field of geometry itself. This article focuses on one of the cases studied. The pair was selected due to be representative of most students and due to their communication skills.展开更多
In an attempt to enhance productivity as well as drought tolerance of barley cultivar, a 5 × 5 diallel cross involving rainfed cultivars was made. Of the 10 crosses, cross K603 x K560 was most promising as it yie...In an attempt to enhance productivity as well as drought tolerance of barley cultivar, a 5 × 5 diallel cross involving rainfed cultivars was made. Of the 10 crosses, cross K603 x K560 was most promising as it yielded highest number of recombinants (21 in irrigated and 36 in rainfed conditions); the cultivar K506 was considered as drought resistant (drought susceptibility index 〈 1). A total of 22 out of 64 and 18 out of 59 most promising F2 recombinants in irrigated and rainfed conditions, respectively from 6 crosses were evaluated for yield, harvest index as well as proline content. All the recombinants selected under rainfed condition (including a few from irrigated condition) showed enhanced level of proline content coupled with high grain yield and harvest index. Further, a total of twenty-nine segregants (12 rainfed and 17 irrigated derived cultures) showing significantly higher values of proline content and grain yield were grown during 2007-2008 under both the environments, rainfed and irrigated to determine the geometric mean (GM) and drought susceptibility index (S). The segregants (Culture No. 8, 10 & 13) derived from cross K 603 × K 560 and culture No. 5 from K 560 × RD 2508 gave maximum mean yield under rainfed and geometric mean coupled with lower drought susceptibility index (S). Also, it has been observed that the transgressive segregants selected from limited water environment (rainfed) performed better than those selected from irrigated environment for higher grain yield and drought tolerance.展开更多
The polymer N2200, with its π-conjugated backbone composed of alternating naphthalene diimide(NDI) and bithiophene(DT)units, has been widely used as an acceptor for all-polymer solar cells(all-PSCs) owing to its high...The polymer N2200, with its π-conjugated backbone composed of alternating naphthalene diimide(NDI) and bithiophene(DT)units, has been widely used as an acceptor for all-polymer solar cells(all-PSCs) owing to its high electron mobility and suitable ionization potential and electron affinity. Here, we developed two naphthalene diimide derivatives by modifying the molecular geometry of N2200 through the incorporation of a truxene unit as the core and NDI-DTas the branches. These starburst polymers exhibited absorption spectra and molecular orbital energy levels that were comparable to N2200. These copolymers were paired with the wide-bandgap polymer donor PTz BI-O to fabricate all-polymer solar cells(all-PSCs), which displayed impressive power conversion efficiencies up to 8.00%. The improved photovoltaic performances of all-PSCs based on these newly developed starburst acceptors can be ascribed to the combination of increased charge carrier mobilities, reduced bimolecular recombination, and formation of more favorable film morphology. These findings demonstrate that the construction of starburst polymer acceptors is a feasible strategy for the fabrication of high-performance all-PSCs.展开更多
Nowadays,the electromagnetic properties of artificial photonic materials can be well-tuned via designs over their composition and geometries.However,engineering the properties of artificial materials at the nanoscale ...Nowadays,the electromagnetic properties of artificial photonic materials can be well-tuned via designs over their composition and geometries.However,engineering the properties of artificial materials at the nanoscale is challenging and costly.Here we demonstrate a facile and low-cost method for fabricating large-area silver nanoparticle metasurfaces(AgNPMSs)by using the vectorial holography-mediated growth technique.The AgNPMS,which can be regarded as a hologram device,possesses excellent chiroptical properties.The vectorial holographic technique may open avenues for fabricating novel chiroptical metamaterials with large degrees of freedom,which can be further used for beam steering,photocatalysis,biosensing,etc.展开更多
Vertical nanowire arrays are increasingly investigated for their applications in steering cell behavior. The geometry of the array is an important parameter, which influences the morphology and adhesion of cells. Here...Vertical nanowire arrays are increasingly investigated for their applications in steering cell behavior. The geometry of the array is an important parameter, which influences the morphology and adhesion of cells. Here, we investigate the effects of array geometry on the morphology of MCF7 cancer cells and MCF10A normal-like epithelial cells. Different gallium phosphide nanowire array-geometries were produced by varying the nanowire density and diameter. Our results show that the cell size is smaller on nanowires compared to flat gallium phosphide. The cell area decreases with increasing the nanowire density on the substrate. We observed an effect of the nanowire diameter on MCF10A cells, with a decreased cell area on 40 nm diameter nanowires, compared to 60 and 80 nm diameter nanowires in high-density arrays. The focal adhesion morphology depends on the extent to which cells are contacting the substrate. For low nanowire densities and diameters, ceils are lying on the substrate and we observed large focal adhesions at the cell edges. In contrast, for high nanowire densities and diameters, cells are lying on top of the nanowires and we observed point-like focal adhesions distributed over the whole cell. Our results constitute a step towards the ability to fine-tune cell behavior on nanowire arrays.展开更多
In this paper, I continue the study of the mathematical models presented in [J. C. Larsen, Models of cancer growth, J. Appl. Math. Comput. 53(1-2) (2015) 613-645] and [J. C. Larsen, The bistability theorem in a mo...In this paper, I continue the study of the mathematical models presented in [J. C. Larsen, Models of cancer growth, J. Appl. Math. Comput. 53(1-2) (2015) 613-645] and [J. C. Larsen, The bistability theorem in a model of metastatic cancer, to appear in Appl. Math.]. I shall prove the bistability theorem for the ODE model from [Larsen, 2015]. It is a mass action kinetic system in the variables C cancer, GF growth factor and GI growth inhibitor. This theorem says that for some values of the parameters, there exist two positive singular points c*+ = (C*+, GF*., GI*+), c*2- = (C*-, GF*, GI*-) of the vector field. Here C*- 〈 C*+ and e. is stable and c*+ is unstable, see Sec. 2. There is also a discrete model in [Larsen, 2015], it is a linear map (T) on three-dimensional Euclidean vector space with variables (C, GF, GI), where these variables have the same meaning as in the ODE model above. In [Larsen, 2015], I showed that one can sometimes find attine vector fields on three-dimensional Euclidean vector space whose time one map is T. I shall also show this in the present paper in a more general setting than in [Larsen, 2015]. This enables me to find an expression for the rate of change of cancer growth on the coordinate hyperplane C = 0 in Euclidean vector space. I also present an ODE model of cancer metastasis with variables C, CM, CF,GI, where C is primary cancer and CM is metastatic cancer and GF, GI are growth factors and growth inhibitors, respectively.展开更多
After half a century research, the mechanical theorem proving in geometries has become an active research topic in the automated reasoning field. This review involves three approaches on automated generating readable ...After half a century research, the mechanical theorem proving in geometries has become an active research topic in the automated reasoning field. This review involves three approaches on automated generating readable machine proofs for geometry theorems which include search methods, coordinate-free methods, and formal logic methods. Some critical issues about these approaches are also discussed. Furthermore, the authors propose three further research directions for the readable machine proofs for geometry theorems, including geometry inequalities, intelligent geometry softwares and machine learning.展开更多
In 2004,Tong found bounds for the approximation quality of a regular continued fraction convergent to a rational number,expressed in bounds for both the previous and next approximation.The authors sharpen his results ...In 2004,Tong found bounds for the approximation quality of a regular continued fraction convergent to a rational number,expressed in bounds for both the previous and next approximation.The authors sharpen his results with a geometric method and give both sharp upper and lower bounds.The asymptotic frequencies that these bounds occur are also calculated.展开更多
Our motivation is to build a systematic method in order to investigate the structure of cluster algebras of geometric type. The method is given through the notion of mixing-type sub-seeds, the theory of seed homomorph...Our motivation is to build a systematic method in order to investigate the structure of cluster algebras of geometric type. The method is given through the notion of mixing-type sub-seeds, the theory of seed homomorphisms and the view-point of gluing of seeds. As an application, for(rooted) cluster algebras, we completely classify rooted cluster subalgebras and characterize rooted cluster quotient algebras in detail. Also,we build the relationship between the categorification of a rooted cluster algebra and that of its rooted cluster subalgebras. Note that cluster algebras of geometric type studied here are of the sign-skew-symmetric case.展开更多
基金Project(51676211)supported by the National Natural Science Foundation of ChinaProject(2015zzts044)supported by Innovation Foundation for Postgraduate of Central South University,ChinaProject(2017SK2253)supported by the Key R&D Plan of Hunan Province,China
文摘The bubble growth and detachment behavior in the bottom blowing process were investigated. Four multi-hole nozzle configurations with different opening ratios were assessed experimentally using high-speed photography and digital image processing. For these configurations, the experiments reveal that the bubble growth consists of a petal-like stage, an expansion stage and a detachment stage. The petal-like shape is qualitatively described through the captured images, while the non-spherical bubbles are analyzed by the aspect ratio. The bubble size at the detachment is quantified by the maximum caliper distance and the bubble equivalent diameter. Considering the dependence on the opening ratio, different prediction models for the ratio of maximum caliper distance to hydraulic diameter of the nozzle outlet and the dimensionless bubble diameter are established. The comparative analysis results show that the proposed prediction model can accurately predict the bubble detachment size under the condition of multi-hole nozzles.
文摘Italian ray grass and oat are two grass species characterized by their ability to adjust tropical climate conditions. This study proposed to assess forage productivities to allow an appropriate mowing period determination in their use as dairy female feed in Madagascar. A test on small plots has been set up in the southern part of the capital city Antananarivo during one dry period (4 months). Live observations followed by laboratory proximate analyses have been performed for forage productivity and feeding value determination. Cultivated on tanety (hill), irrigated in counter season, results show that: (I) oat higher height (H = 96.7 cm) than Italian ray grass (H= 69.4 cm) at 99 days of age; (2) similar biomass productivity; (3) dry matter yields significantly different (p = 0.05); (4) certain similarity between dry matter yields and FMU (fodder milk unit) score evolution; (5) leafy stage of Italian ray grasses at 99 days of age; (6) mid-flowering stage for oats during the same period. Cell wall content, crude fiber and dry matter contents increased with age (p = 0.05). Crude proteins and minerals evolved in opposite directions. Gross energy content did not present precise variation with age. This study allowed that for an acceptable quantitative and qualitative production during dry seasons, good mowing period for Italian ray grass could start at 76 days age, while oat could start being harvested at 68 days.
文摘The paper addresses the formulation of rate equations, via objective time derivatives, within continuum physics. The concept of objectivity is reviewed and distinction is made with material frame-indifference whose meaning is restricted to the invariance of the balance equations relative to Galilean frames. Objective time derivatives are defined to leave the tensor character of the appropriate field invariant within the set of Euclidean frames. Rate equations are required to involve objective time derivatives and to be consistent with the second law of thermodynamics. Here the general structure of objective time derivatives is established and the known derivatives of the physical literature are shown to be particular cases. Next, to fix ideas, a rate equation is considered for the model of heat conduction via a generalization of the Maxwell-Cattaneo equation with higher-order gradients as in the Guyer-Krumhansl equation. The thermodynamic restrictions are investigated and the expected effects, of the selected derivative of the heat flux, on the stress tensor are derived.
基金Projects(50676068,50576024)supported by the National Natural Science Foundation of China
文摘In thermoacoustic system,the characteristic of complex compliance of a regenerator has a great influence on energy stored and dissipation of the whole engine.In order to investigate the performance of regenerators with different matrix geometries and materials coupled with different acoustic systems,an experimental measurement and analysis method was presented.By measuring the resonant frequency,the complex compliance and quality factor of five kinds of matrix were experimentally analyzed respectively in the system of loudspeaker-driven thermoacoustic resonator(TAR)with different lengths.The experimental results show that the real part of complex compliance of the regenerator with pin-array has a maximum value among the measured matrixes and its quality factor is the largest(28.222)with the least dissipation factor of 0.035 4.So the pin-array matrix is testified to behave more excellently on the energy conversion than other matrixes.Compared with other factors the complex compliance of a regenerator contributes more to the performance of a thermoacoustic system.
基金Project(51378457)supported by the National Natural Science Foundation of China
文摘An essential step for the realization of free-form surface structures is to create an efficient structural gird that satisfies not only the architectural aesthetics,but also the structural performance.Employing the main stress trajectories as the representation of force flows on a free-form surface,an automatic grid generation approach is proposed for the architectural design.The algorithm automatically plots the main stress trajectories on a 3D free-form surface,and adopts a modified advancing front meshing technique to generate the structural grid.Based on the proposed algorithm,an automatic grid generator named "St-Surmesh" is developed for the practical architectural design of free-form surface structure.The surface geometry of one of the Sun Valleys in Expo Axis for the Expo Shanghai 2010 is selected as a numerical example for validating the proposed approach.Comparative studies are performed to demonstrate how different structural grids affect the design of a free-form surface structure.
文摘Arthritis, most notably rheumatoid arthritis, can destroy the surfaces of the bones; the ideal solution for this is T JR (total joint replacement), which would restore joint functionality, maintain correct aesthetics and eradicate pain for the patient. Current metacarpophalangeal TJR do not provide the normal biomechanical range of motion and functionality. The proposed design attempts to correct this through the use of design geometry and functional anatomy. Numerical analysis is used in conjunction with computational solid modeling to compare a one-piece silicone implant with the proposed T JR. Peak stresses during flexion for the proposed design did not exceed 1.2 MPa, where as soft implants approach 100 MPa to 1,000 MPa for peak stress values. The proposed design, due to high stress tolerances with low deformation, along with functionality and biomechanics, seems to be an appropriate replacement for one-piece silicone implant.
文摘Today's math education basic syllabus gives an ever increasing emphasis to Geometry and Patterns. Curricula also advocate an approach that allows student to understand the concepts involved supported by dynamical computer tools. However, there is not much research work joining these paradigms. Therefore, a case study was developed, with 9th grade students (14-15 years old), to evaluate the impact of a creative approach to isometries and symmetries-friezes, rosaceas (rosettes) and wallpapers-centered in patterns (reproduction, continuation, completion, description and creation) and using Geometer's Sketchpad software to solve, mainly in pairs, and discuss, with the whole class, the challenging tasks proposed, involving the formulation of hypothesis, argumentation and justification of the reasoning. The statistical analysis of the quantifiable data and content analysis of the qualitative data, collecting trough enquiry, direct observation and documental analysis (involving questionnaires, field notes, logbook, pre-tests and post-test, other works of the students including those computer related, and internal documents of the school) enable to conclude positively regarding the main research question underlying the study. In fact, it led to the conclusion that the teaching strategy implemented has contributed to deepen the student's knowledge and skills on geometry, mathematical communication and autonomy as well as to develop a closer relation with the field of geometry itself. This article focuses on one of the cases studied. The pair was selected due to be representative of most students and due to their communication skills.
文摘In an attempt to enhance productivity as well as drought tolerance of barley cultivar, a 5 × 5 diallel cross involving rainfed cultivars was made. Of the 10 crosses, cross K603 x K560 was most promising as it yielded highest number of recombinants (21 in irrigated and 36 in rainfed conditions); the cultivar K506 was considered as drought resistant (drought susceptibility index 〈 1). A total of 22 out of 64 and 18 out of 59 most promising F2 recombinants in irrigated and rainfed conditions, respectively from 6 crosses were evaluated for yield, harvest index as well as proline content. All the recombinants selected under rainfed condition (including a few from irrigated condition) showed enhanced level of proline content coupled with high grain yield and harvest index. Further, a total of twenty-nine segregants (12 rainfed and 17 irrigated derived cultures) showing significantly higher values of proline content and grain yield were grown during 2007-2008 under both the environments, rainfed and irrigated to determine the geometric mean (GM) and drought susceptibility index (S). The segregants (Culture No. 8, 10 & 13) derived from cross K 603 × K 560 and culture No. 5 from K 560 × RD 2508 gave maximum mean yield under rainfed and geometric mean coupled with lower drought susceptibility index (S). Also, it has been observed that the transgressive segregants selected from limited water environment (rainfed) performed better than those selected from irrigated environment for higher grain yield and drought tolerance.
基金supported by the Ministry of Science and Technology of China(2014CB643501)the National Natural Science Foundation of China(51673069,91633301,21520102006,21761132001)+1 种基金Foundation of Guangzhou Science and Technology Project(201707020019,201607020010)the Pearl River S&T Nova Program of Guangzhou(201710010021)
文摘The polymer N2200, with its π-conjugated backbone composed of alternating naphthalene diimide(NDI) and bithiophene(DT)units, has been widely used as an acceptor for all-polymer solar cells(all-PSCs) owing to its high electron mobility and suitable ionization potential and electron affinity. Here, we developed two naphthalene diimide derivatives by modifying the molecular geometry of N2200 through the incorporation of a truxene unit as the core and NDI-DTas the branches. These starburst polymers exhibited absorption spectra and molecular orbital energy levels that were comparable to N2200. These copolymers were paired with the wide-bandgap polymer donor PTz BI-O to fabricate all-polymer solar cells(all-PSCs), which displayed impressive power conversion efficiencies up to 8.00%. The improved photovoltaic performances of all-PSCs based on these newly developed starburst acceptors can be ascribed to the combination of increased charge carrier mobilities, reduced bimolecular recombination, and formation of more favorable film morphology. These findings demonstrate that the construction of starburst polymer acceptors is a feasible strategy for the fabrication of high-performance all-PSCs.
基金the National Natural Science Foundation of China(62075093 and 61805113)the Guangdong Innovative and Entrepreneurial Research Team Program(2017ZT07C071)+1 种基金the Natural Science Foundation of Guangdong Province(2017A030313034 and 2018A030310224)Shenzhen Science and Technology Innovation Commission(JCYJ20170817111349280,JCYJ20180305180635082,and GJHZ20180928155207206)。
文摘Nowadays,the electromagnetic properties of artificial photonic materials can be well-tuned via designs over their composition and geometries.However,engineering the properties of artificial materials at the nanoscale is challenging and costly.Here we demonstrate a facile and low-cost method for fabricating large-area silver nanoparticle metasurfaces(AgNPMSs)by using the vectorial holography-mediated growth technique.The AgNPMS,which can be regarded as a hologram device,possesses excellent chiroptical properties.The vectorial holographic technique may open avenues for fabricating novel chiroptical metamaterials with large degrees of freedom,which can be further used for beam steering,photocatalysis,biosensing,etc.
基金supported by the Swedish Research Council (VR)Nano Lund, the Crafoord Foundation+1 种基金the China Scholarship Council (CSC)by a Donation from Carolina Le Prince with the “Kalenderflickorna” and Associated Sponsors
文摘Vertical nanowire arrays are increasingly investigated for their applications in steering cell behavior. The geometry of the array is an important parameter, which influences the morphology and adhesion of cells. Here, we investigate the effects of array geometry on the morphology of MCF7 cancer cells and MCF10A normal-like epithelial cells. Different gallium phosphide nanowire array-geometries were produced by varying the nanowire density and diameter. Our results show that the cell size is smaller on nanowires compared to flat gallium phosphide. The cell area decreases with increasing the nanowire density on the substrate. We observed an effect of the nanowire diameter on MCF10A cells, with a decreased cell area on 40 nm diameter nanowires, compared to 60 and 80 nm diameter nanowires in high-density arrays. The focal adhesion morphology depends on the extent to which cells are contacting the substrate. For low nanowire densities and diameters, ceils are lying on the substrate and we observed large focal adhesions at the cell edges. In contrast, for high nanowire densities and diameters, cells are lying on top of the nanowires and we observed point-like focal adhesions distributed over the whole cell. Our results constitute a step towards the ability to fine-tune cell behavior on nanowire arrays.
文摘In this paper, I continue the study of the mathematical models presented in [J. C. Larsen, Models of cancer growth, J. Appl. Math. Comput. 53(1-2) (2015) 613-645] and [J. C. Larsen, The bistability theorem in a model of metastatic cancer, to appear in Appl. Math.]. I shall prove the bistability theorem for the ODE model from [Larsen, 2015]. It is a mass action kinetic system in the variables C cancer, GF growth factor and GI growth inhibitor. This theorem says that for some values of the parameters, there exist two positive singular points c*+ = (C*+, GF*., GI*+), c*2- = (C*-, GF*, GI*-) of the vector field. Here C*- 〈 C*+ and e. is stable and c*+ is unstable, see Sec. 2. There is also a discrete model in [Larsen, 2015], it is a linear map (T) on three-dimensional Euclidean vector space with variables (C, GF, GI), where these variables have the same meaning as in the ODE model above. In [Larsen, 2015], I showed that one can sometimes find attine vector fields on three-dimensional Euclidean vector space whose time one map is T. I shall also show this in the present paper in a more general setting than in [Larsen, 2015]. This enables me to find an expression for the rate of change of cancer growth on the coordinate hyperplane C = 0 in Euclidean vector space. I also present an ODE model of cancer metastasis with variables C, CM, CF,GI, where C is primary cancer and CM is metastatic cancer and GF, GI are growth factors and growth inhibitors, respectively.
基金supported by the Funds of the Chinese Academy of Sciences for Key Topics in Innovation Engineering under Grant No.KJCX2-YW-S02
文摘After half a century research, the mechanical theorem proving in geometries has become an active research topic in the automated reasoning field. This review involves three approaches on automated generating readable machine proofs for geometry theorems which include search methods, coordinate-free methods, and formal logic methods. Some critical issues about these approaches are also discussed. Furthermore, the authors propose three further research directions for the readable machine proofs for geometry theorems, including geometry inequalities, intelligent geometry softwares and machine learning.
文摘In 2004,Tong found bounds for the approximation quality of a regular continued fraction convergent to a rational number,expressed in bounds for both the previous and next approximation.The authors sharpen his results with a geometric method and give both sharp upper and lower bounds.The asymptotic frequencies that these bounds occur are also calculated.
基金supported by National Natural Science Foundation of China (Grant Nos. 11671350 and 11571173)
文摘Our motivation is to build a systematic method in order to investigate the structure of cluster algebras of geometric type. The method is given through the notion of mixing-type sub-seeds, the theory of seed homomorphisms and the view-point of gluing of seeds. As an application, for(rooted) cluster algebras, we completely classify rooted cluster subalgebras and characterize rooted cluster quotient algebras in detail. Also,we build the relationship between the categorification of a rooted cluster algebra and that of its rooted cluster subalgebras. Note that cluster algebras of geometric type studied here are of the sign-skew-symmetric case.