Mg-Zn-RE alloys typically exhibit non-basal texture,weak dispersion hardening,and low yield strength.In this study,we designed a dilute quaternary Mg-0.6Zn-0.4Nd-0.2Ca(wt.%)alloy.Then,applied pre-strain and heat treat...Mg-Zn-RE alloys typically exhibit non-basal texture,weak dispersion hardening,and low yield strength.In this study,we designed a dilute quaternary Mg-0.6Zn-0.4Nd-0.2Ca(wt.%)alloy.Then,applied pre-strain and heat treatment to investigate the balance of yield strength and ductility via solute atom segregation at twin boundaries and nanophase modifications.The results indicated that Zn and Nd elements tend to co-segregate at the twin boundary,while Ca element segregates alone and presents a discontinuous distribution.Nanoscale precipitates of(Mg,Zn)_(3)Nd and Mg_(2)Ca with the size of 5∼20 nm underwent significant preferential precipitation at the twin boundary.Moreover,compared with Ca atoms,Zn atoms tend to combine with Nd atoms more preferentially towards the stacking faults,thereby forming a high-density monolayer Guinier-Preston(G.P.)zone.The segregation and precipitation of solute atoms at the twin boundary and the stacking faults increased the friction stress of twinning dislocations and lattice dislocations,thus improving the strength.Pinned twin boundaries facilitate the transition from basalslip to pyramidal<c+a>slip due to the small geometrical compatibility factor(m′)value as well as the Schmid factor(SF)incompatibility.As a result,the pre-strained and heat-treated specimen’s yield strength exhibits a 141%increase relative to the initial state specimen,accompanied by a modest improvement in ductility.The mechanism of multi-element segregation and precipitation at twin boundaries,and G.P.zone formation was discussed in detail.展开更多
The existence of solutions for singular nonlinear two point boundary value problems subject to Sturm Liouville boundary conditions with p Laplacian operators is studied by the method of upper and lower solution...The existence of solutions for singular nonlinear two point boundary value problems subject to Sturm Liouville boundary conditions with p Laplacian operators is studied by the method of upper and lower solutions. The proof is based on an application of Schauder’s fixed point theorem to a modified problem whose solutions are that of the original one. At the same time, Arzela Ascoli theorem is used to prove that the defined operator N is a compact map.展开更多
The existence of multiple positive solutions for a class of higher order p Laplacian boundary value problem is studied. By means of the Leggett Williams fixed point theorem in cones, existence criteria which e...The existence of multiple positive solutions for a class of higher order p Laplacian boundary value problem is studied. By means of the Leggett Williams fixed point theorem in cones, existence criteria which ensure the existence of at least three positive solutions of the boundary value problem are established.展开更多
The interface energies and electronic structures of(112) grain boundaries of Cu In Se2 thin films were investigated by first-principle calculations.It is found that the grain boundary with a Cu vacancy has low interfa...The interface energies and electronic structures of(112) grain boundaries of Cu In Se2 thin films were investigated by first-principle calculations.It is found that the grain boundary with a Cu vacancy has low interface energy and exists widely in the films.The Cu deficiency may cause the charge imbalance and result in an upward band bending at the grain boundary.It also weakens the repulsion between Cu-3d orbital and Se-4p orbital and leads to the downward shift of valence band maximum.The two mechanisms,namely the band bending from the charge imbalance and the depression of the valence band maximum, have effects on the(112) grain boundaries with different defects.The change of band structure forms a potential barrier to prevent electrons or holes from approaching the grain boundary and reduces their recombination.This might be used to explain the effects of the grain boundary on carrier transportation and why polycrystalline Cu(In,Ga)Se2thin film solar cells have better performance than single-crystal cells.展开更多
The Meishan section of China has been confirmed as the ＂Global Stratotype Section and Point＂ of the P/T boundary. In the section, the authors found several types of iron grains, including pyrite, pure iron grains an...The Meishan section of China has been confirmed as the ＂Global Stratotype Section and Point＂ of the P/T boundary. In the section, the authors found several types of iron grains, including pyrite, pure iron grains and goethite. From the research of macro minerals, it is easy to find that the grains rich in iron appear from the bottom of the event layer of the section. In other words, it is probably residue of the geochemical catastrophe of that time. Therefore, it is important to trace the source of these iron grains and their relationships, which probably provides evidence for volcanic eruption or impact-volcanoes and has directive significance to the crisis during the P/T transitional period. Through the study of the characterization and relationships of these iron grains, the authors make a preliminary discussion on the P/T mass extinction.展开更多
The present note is concerned with two connected and highly important fundamental questions of physics and cosmology, namely if E8E8 Lie symmetry group describes the universe and where cosmic dark energy comes from. F...The present note is concerned with two connected and highly important fundamental questions of physics and cosmology, namely if E8E8 Lie symmetry group describes the universe and where cosmic dark energy comes from. Furthermore, we reason following Wheeler, Hartle and Hawking that since the boundary of a boundary is an empty set which models the quantum wave of the cosmos, then it follows that dark energy is a fundamental physical phenomenon associated with the boundary of the holographic boundary. This leads directly to a clopen universe which is its own Penrose tiling-like multiverse with energy density in full agreement with COBE, WMAP and Type 1a supernova cosmic measurements.展开更多
The present study evaluated the expression of key molecules and the status of DNA in both oral squamous cell carcinoma（OSCC） and adjacent tissues to establish a molecular surgical boundary and provide a cancer progr...The present study evaluated the expression of key molecules and the status of DNA in both oral squamous cell carcinoma（OSCC） and adjacent tissues to establish a molecular surgical boundary and provide a cancer progression model. Biopsy samples from 50 OSCC patients were divided into T（cancer）, P1（0–0.5 cm）, P2（0.5–1 cm）, P3（1–1.5 cm） and P4（1.5–2 cm） groups based on the distances from the visible boundary of the primary focus. Twenty samples of normal mucosa were used as controls. We used immunohistochemical staining and flow cytometry to evaluate p53, p21CIP1/WAF1, e IF4 E and Ki-67 expression and to determine DNA status, respectively. Sub-mucosal invasion was present in the P1 and P2 groups as determined by haematoxylin and eosin staining.Mutant p53 expression decreased gradually from cancerous to normal mucosae, whereas p21CIP1/WAF1 expression displayed an opposite trend. e IF4 E expression decreased from cancerous to normal mucosae. Ki-67 expression, the heteroploidy ratio, S-phase fraction and proliferative index decreased gradually with the distance from the tumour centre. Based on these results, we suggest that the resection boundary in OSCC surgery should be beyond 2 cm from the tumour. Additionally, the adjacent tissues of the primary focus could be used as a model for assessing cancer progression.展开更多
Two-dimensional tidal open boundary conditions of the M2 constituent in the Bohai and Yellow Seas(BYS) have been estimated by assimilating T/P altimeter data.During inversion,independent point(IP) strategy was used,in...Two-dimensional tidal open boundary conditions of the M2 constituent in the Bohai and Yellow Seas(BYS) have been estimated by assimilating T/P altimeter data.During inversion,independent point(IP) strategy was used,in which several IPs on the open boundary is assumed,values at these IPs can be optimized with an adjoint method,and those at other grid points are determined by linearly interpolating the values at IPs.The reasonability and feasibility of the model are tested by ideal twin experiments.In the practical experiment(PE) after assimilation,the cost function may reach 1% or less of its initial value.Mean absolute errors in amplitude and phase can be less than 5 cm and 5°,respectively,and the obtained co-chart can show the character of the M2 constituent in the BYS.The results of the PE indicate that using only two IPs on the open boundary can yield better simulated results.展开更多
In this paper, we consider the existence of three nontrivial solutions for a discrete non-linear multiparameter periodic problem involving the p-Laplacian. By using the similar method for the Dirichlet boundary value ...In this paper, we consider the existence of three nontrivial solutions for a discrete non-linear multiparameter periodic problem involving the p-Laplacian. By using the similar method for the Dirichlet boundary value problems in [C. Bonanno and P. Candito, Appl. Anal., 88（4） （2009）, pp. 605-616], we construct two new strong maximum principles and obtain that the boundary value problem has three positive solutions for λ and μ in some suitable intervals. The approaches we use are the critical point theory.展开更多
基金support from the National Natural Science Foundation of China(Grant No 52471119,Grant No 52301133 and Grant No 52271092)the Young Elite Scientists Sponsorship Program by China Association for Science and Technology(Grant No YESS20210415)+3 种基金the China Postdoctoral Science Foundation(Grant No 2023M730276)the Chongqing Science and Technology Commission(Grant No CSTB2023NSCQ-MSX0901 and Grant No CSTB2024NSCQ-LZX0006)the Chongqing Municipal Education Commission(Grant No KJQN202101525)the Chongqing University of Science and Technology(Grant No ckrc2021022 and Grant No YKJCX2420218).
文摘Mg-Zn-RE alloys typically exhibit non-basal texture,weak dispersion hardening,and low yield strength.In this study,we designed a dilute quaternary Mg-0.6Zn-0.4Nd-0.2Ca(wt.%)alloy.Then,applied pre-strain and heat treatment to investigate the balance of yield strength and ductility via solute atom segregation at twin boundaries and nanophase modifications.The results indicated that Zn and Nd elements tend to co-segregate at the twin boundary,while Ca element segregates alone and presents a discontinuous distribution.Nanoscale precipitates of(Mg,Zn)_(3)Nd and Mg_(2)Ca with the size of 5∼20 nm underwent significant preferential precipitation at the twin boundary.Moreover,compared with Ca atoms,Zn atoms tend to combine with Nd atoms more preferentially towards the stacking faults,thereby forming a high-density monolayer Guinier-Preston(G.P.)zone.The segregation and precipitation of solute atoms at the twin boundary and the stacking faults increased the friction stress of twinning dislocations and lattice dislocations,thus improving the strength.Pinned twin boundaries facilitate the transition from basalslip to pyramidal<c+a>slip due to the small geometrical compatibility factor(m′)value as well as the Schmid factor(SF)incompatibility.As a result,the pre-strained and heat-treated specimen’s yield strength exhibits a 141%increase relative to the initial state specimen,accompanied by a modest improvement in ductility.The mechanism of multi-element segregation and precipitation at twin boundaries,and G.P.zone formation was discussed in detail.
文摘The existence of solutions for singular nonlinear two point boundary value problems subject to Sturm Liouville boundary conditions with p Laplacian operators is studied by the method of upper and lower solutions. The proof is based on an application of Schauder’s fixed point theorem to a modified problem whose solutions are that of the original one. At the same time, Arzela Ascoli theorem is used to prove that the defined operator N is a compact map.
文摘The existence of multiple positive solutions for a class of higher order p Laplacian boundary value problem is studied. By means of the Leggett Williams fixed point theorem in cones, existence criteria which ensure the existence of at least three positive solutions of the boundary value problem are established.
基金financially supported by the Natural Science Foundation of Jiangsu (No. BK2011033)
文摘The interface energies and electronic structures of(112) grain boundaries of Cu In Se2 thin films were investigated by first-principle calculations.It is found that the grain boundary with a Cu vacancy has low interface energy and exists widely in the films.The Cu deficiency may cause the charge imbalance and result in an upward band bending at the grain boundary.It also weakens the repulsion between Cu-3d orbital and Se-4p orbital and leads to the downward shift of valence band maximum.The two mechanisms,namely the band bending from the charge imbalance and the depression of the valence band maximum, have effects on the(112) grain boundaries with different defects.The change of band structure forms a potential barrier to prevent electrons or holes from approaching the grain boundary and reduces their recombination.This might be used to explain the effects of the grain boundary on carrier transportation and why polycrystalline Cu(In,Ga)Se2thin film solar cells have better performance than single-crystal cells.
基金This research was supported by the National Natural Science Foundation of China （Nos. 40232025 40072055+1 种基金 40572020） the Research Fund for the Doctoral Program of Higher Education （No. 20040290005）.
文摘The Meishan section of China has been confirmed as the ＂Global Stratotype Section and Point＂ of the P/T boundary. In the section, the authors found several types of iron grains, including pyrite, pure iron grains and goethite. From the research of macro minerals, it is easy to find that the grains rich in iron appear from the bottom of the event layer of the section. In other words, it is probably residue of the geochemical catastrophe of that time. Therefore, it is important to trace the source of these iron grains and their relationships, which probably provides evidence for volcanic eruption or impact-volcanoes and has directive significance to the crisis during the P/T transitional period. Through the study of the characterization and relationships of these iron grains, the authors make a preliminary discussion on the P/T mass extinction.
文摘The present note is concerned with two connected and highly important fundamental questions of physics and cosmology, namely if E8E8 Lie symmetry group describes the universe and where cosmic dark energy comes from. Furthermore, we reason following Wheeler, Hartle and Hawking that since the boundary of a boundary is an empty set which models the quantum wave of the cosmos, then it follows that dark energy is a fundamental physical phenomenon associated with the boundary of the holographic boundary. This leads directly to a clopen universe which is its own Penrose tiling-like multiverse with energy density in full agreement with COBE, WMAP and Type 1a supernova cosmic measurements.
基金supported by the National Natural Science Foundation of China (Grant Nos. 81001209 and 81172578)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (Grant No. 81321002)
文摘The present study evaluated the expression of key molecules and the status of DNA in both oral squamous cell carcinoma（OSCC） and adjacent tissues to establish a molecular surgical boundary and provide a cancer progression model. Biopsy samples from 50 OSCC patients were divided into T（cancer）, P1（0–0.5 cm）, P2（0.5–1 cm）, P3（1–1.5 cm） and P4（1.5–2 cm） groups based on the distances from the visible boundary of the primary focus. Twenty samples of normal mucosa were used as controls. We used immunohistochemical staining and flow cytometry to evaluate p53, p21CIP1/WAF1, e IF4 E and Ki-67 expression and to determine DNA status, respectively. Sub-mucosal invasion was present in the P1 and P2 groups as determined by haematoxylin and eosin staining.Mutant p53 expression decreased gradually from cancerous to normal mucosae, whereas p21CIP1/WAF1 expression displayed an opposite trend. e IF4 E expression decreased from cancerous to normal mucosae. Ki-67 expression, the heteroploidy ratio, S-phase fraction and proliferative index decreased gradually with the distance from the tumour centre. Based on these results, we suggest that the resection boundary in OSCC surgery should be beyond 2 cm from the tumour. Additionally, the adjacent tissues of the primary focus could be used as a model for assessing cancer progression.
基金Supported by the State Ministry of Science and Technology of China (Nos.2007AA09Z118,2008AA09A402)the National Natural Science Foundation of China(No.41076006)the Ministry of Education's 111 Project(No.B07036)
文摘Two-dimensional tidal open boundary conditions of the M2 constituent in the Bohai and Yellow Seas(BYS) have been estimated by assimilating T/P altimeter data.During inversion,independent point(IP) strategy was used,in which several IPs on the open boundary is assumed,values at these IPs can be optimized with an adjoint method,and those at other grid points are determined by linearly interpolating the values at IPs.The reasonability and feasibility of the model are tested by ideal twin experiments.In the practical experiment(PE) after assimilation,the cost function may reach 1% or less of its initial value.Mean absolute errors in amplitude and phase can be less than 5 cm and 5°,respectively,and the obtained co-chart can show the character of the M2 constituent in the BYS.The results of the PE indicate that using only two IPs on the open boundary can yield better simulated results.
基金Supported by NSFC(11326127,11101335)NWNULKQN-11-23the Fundamental Research Funds for the Gansu Universities
文摘In this paper, we consider the existence of three nontrivial solutions for a discrete non-linear multiparameter periodic problem involving the p-Laplacian. By using the similar method for the Dirichlet boundary value problems in [C. Bonanno and P. Candito, Appl. Anal., 88（4） （2009）, pp. 605-616], we construct two new strong maximum principles and obtain that the boundary value problem has three positive solutions for λ and μ in some suitable intervals. The approaches we use are the critical point theory.
