Solid polymer electrolytes have been considered as the promising candidates to improve the safety and stability of high-energy lithium metal batteries.However,the practical applications of solid polymer electrolytes a...Solid polymer electrolytes have been considered as the promising candidates to improve the safety and stability of high-energy lithium metal batteries.However,the practical applications of solid polymer electrolytes are still limited by the low ionic conductivity,poor interfacial contact with electrodes,narrow electrochemical window and weak mechanical strength.Here,a series of novel block copolymer electrolytes with three-dimensional networks are designed by cross-linked copolymerization of the polyethylene glycol soft segments and hexamethylene diisocyanate trimer hard segments.Their ionic migration performances and interface compatibilities with Li metal anode have been optimized delicately by tailoring the ratio of these functional units.The optimized block copolymer electrolyte has shown an amorphous crystalline structure,a high ionic conductivity of ~5.7×10^(-4)S cm^(-1),high lithium ion transference number(~0.49),wide electrochemical window up to ~4.65 V(vs.Li+/Li) and favorable mechanical strength at 55℃.Furthermore,the enhanced interface compatibility can well support the normal operations of lithium metal batteries using both LiFePO4 and LiNi0.8Co0.15Al0.05O2 cathodes.This study not only paves a new way to develop solid polymer electrolyte with optimizing functional units,but also provides a polymer electrolyte design strategy for the application demand of lithium metal battery.展开更多
The sulfide-based solid-state electrolytes(SEs)reactivity toward moisture and Li-metal are huge barriers that impede their large-scale manufactu ring and applications in all-solid-state lithium batteries(ASSLBs).Herei...The sulfide-based solid-state electrolytes(SEs)reactivity toward moisture and Li-metal are huge barriers that impede their large-scale manufactu ring and applications in all-solid-state lithium batteries(ASSLBs).Herein,we proposed an Al and O dual-doped strategy for Li_(3)PS_(4)SE to regulate the chemical/electrochemical stability of anionic PS_(4)^(3-)tetrahedra to mitigate structural hydrolysis and parasitic reactions at the SE/Li interface.The optimized Li_(3.08)A_(10.04)P_(0.96)S_(3.92)O_(0.08)SE presents the highestσLi+of 3.27 mS cm^(-1),which is~6.8 times higher than the pristine Li_(3)PS_(4)and excellently inhibits the structural hydrolysis for~25 min@25%humidity at RT.DFT calculations confirmed that the enhanced chemical stability was revealed to the intrinsically stable entities,e.g.,POS33-units.Moreover,Li_(3.08)Al_(0.04)P_(0.96)S_(3.92)O_(0.08)SE cycled stably in Li//Li symmetric cell over 1000 h@0.1 mA cm^(-2)/0.1 mA h cm^(-2),could be revealed to Li-Al alloy and Li_(2)Oat SE/Li interface impeding the growth of Li-dendrites during cycling.Resultantly,LNO@LCO/Li_(3.08)Al_(0.04)P_(0.96)S_(3.92)O_(0.08)/Li-In cell delivered initial discharge capacities of 129.8 mA h g^(-1)and 83.74%capacity retention over 300 cycles@0.2 C at RT.Moreover,the Li_(3.08)Al_(0.04)P_(0.96)S_(3.92)O_(0.08)SE presented>90%capacity retention over 200 and 300 cycles when the cell was tested with LiNi_(0.8)Co_(0.15)Al_(0.05)O_(2)(NCA)cathode material vs.5 and 10 mg cm^(-2)@RT.展开更多
Urban land use is always the central focus of urban planners and policymakers when pursuing urban sustainable development.Currently,many studies have explored urban land use using satellite data,but few of them can id...Urban land use is always the central focus of urban planners and policymakers when pursuing urban sustainable development.Currently,many studies have explored urban land use using satellite data,but few of them can identify the social function of land use through these data.In this research,OpenStreetMap(OSM)data are used to extract urban land use social functional units.Firstly,the OSM data are transferred to actual land use types based on the established mapping rules between OSM data and the urban land use classification standards.Then,the improved DBSCAN algorithm is applied with OSM data of the study area after estimating the parameters of the neighborhood radius(Eps)and the minimum polygons(MinPolys)based on the polygon density.With the two estimated parameters,the improved DBSCAN algorithm is used to cluster residential,commercial and public service land use social functional polygons of the OSM data.Following that,the clusters of the three land use types are processed into land use social functional units.The results show that OSM data perform well in determining these three land use social functional clusters using the improved DBSCAN algorithm,and the social functional units display obvious spatial features.展开更多
In this paper we obtained the asymptotic formula of the orthogonal rational function on the unit circle with respect to the weight function μ(z) with preasigned poles, which are in the exterior of the unit disk.
LiMn_(6) hexatomic-rings act as functional units in Li-rich layered oxides(LLOs),which determine the capacity,voltage,and structural stability of LLOs.However,the symmetry of the LiMn_(6) hexatomic-ring is always brok...LiMn_(6) hexatomic-rings act as functional units in Li-rich layered oxides(LLOs),which determine the capacity,voltage,and structural stability of LLOs.However,the symmetry of the LiMn_(6) hexatomic-ring is always broken,especially in the grain surface of LLOs,which will greatly affect its electrochemical performance.Herein,the symmetry-breaking of LiMn_(6) hexatomic-ring in the grain surface of Li_(2)MnO_(3) was studied,and their effect on charge compensation mechanism and structure evolution behavior was thoroughly investigated.The results show that the electrochemical activity of the symmetry-broken LiMn_(6) hexatomic-ring is higher than that of the unbroken LiMn_(6),and the former is more favorable for spinelization on the grain surface.Furthermore,the exposure proportion of crystallographic planes with different symmetry-broken LiMn_(6) hexatomic-ring has also been discussed,which can be adjusted by changing the partial pressure of oxygen.The in-depth understanding of the symmetry-breaking of LiMn_(6) hexatomic-ring will provide more targeted strategies for designing high-performance LLOs cathodes for lithium-ion batteries.展开更多
As a fundamental parameter of the optical crystals,birefringence plays a vital role in many optical applications,such as phase modulation,light splitting,and polarization,especially the phase matching process of the n...As a fundamental parameter of the optical crystals,birefringence plays a vital role in many optical applications,such as phase modulation,light splitting,and polarization,especially the phase matching process of the nonlinear optical crystals.The big birefringence not only benefits to the miniaturization of related devices,but also broadens the phase-matching wavelength range of nonlinear optical crystals.The design and synthesis of crystals with large birefringence becomes a hot research topic due to its more and more important applications in the optical modulation and laser technology fields.Herein,crystals with birefringence greater than 0.05 in the borate system are reviewed and classified according to different birefringent active groups,and the relationship between structure and properties is thoroughly explored.It is hoped that this review will provide a clear understanding of what kinds of building units and arrangements would have more opportunity to get adequate birefringence in borate systems and provide the statistical references to encourage the emergence of better crystal materials with large birefringence.展开更多
Based on a questionnaire survey,the paper made a comparative study on the changes of traditional library positions within the context of the emerging professional positions and functional units at some large academic ...Based on a questionnaire survey,the paper made a comparative study on the changes of traditional library positions within the context of the emerging professional positions and functional units at some large academic libraries in China and in the United States from 1998 to 2007.It describes how some of the library professional positions and functional units have gone through a time period of intensified and proactive position allocation realignment in terms of their rise,decline,fission and/or fusion within the administrative context of their library's evolving changes in missions,objectives and service delivery structure under the impact of the rapid development of information technologies.Such changes are graphically demonstrated in several charts in this paper to highlight the evolutionary development of academic librarianship in general and the waves of changes for library position reallocations in specific in the ten-year period under study.It is believed that such a study can be useful for discerning the overall developing trend of academic librarianship,especially in the area of the rising professional and social status of academic librarianship during this period.The movement of library position allocation realignment was a corresponding response at the time to the influx of applicable information technologies to the library scene.It not only made the library operation to become'leaner and meaner,' but also gave added impetus to the rise of the professional and social status of their practitioners in the society due to the latter's enhanced service delivery innovations and capabilities for meeting their constituencies' timely information needs more satisfactorily.展开更多
Aim The objective of this study was to analyze the oral health among Japanese adults, with and without diabetes mellitus. Methodology The subjects were 518 community residents aged 20 to 91 years in Japan, who partici...Aim The objective of this study was to analyze the oral health among Japanese adults, with and without diabetes mellitus. Methodology The subjects were 518 community residents aged 20 to 91 years in Japan, who participated in the "Akita health and nutrition survey" and the "Akita dental disease survey", conducted in 2006. The surveys comprised a self-administered questionnaire, along with medical and dental examinations. Results Using the community periodontal index (CPI), the mean numbers of sextants presenting codes 0, 1 and 2 were significantly lower in diabetics than non-diabetics among the 59 years or younger age group. Although the mean numbers of sextants with codes 0, 1 and 2 among the 60 to 69 years age group were lower, and sextants with a code X among the 59 years or younger age group were higher in diabetics than non-diabetics, no statistically significant differences were detected. The tendency of lower mean numbers of natural teeth and functional tooth units in diabetics than non-diabetics was observed, however no differences were statistically significant. Conclusion The outcome of periodontal disease seemed to be influenced by the diabetic state to some degree, but a clear association between diabetes and oral health status was not found.展开更多
By means of Delta-function & unit step function to express the force of solid particle on plane inertial shaker's screen, an mathematical model of the differential equation type was set up and solved. Accordin...By means of Delta-function & unit step function to express the force of solid particle on plane inertial shaker's screen, an mathematical model of the differential equation type was set up and solved. According to analysis of the solution, the relation is given between the throw period & displacement with the parameters of shaker design & solid particle. The method of numerical value calculation & analysis for the relation is given too.展开更多
Reusing test cases from existing test case library is quite common in the software testing field. Testing practice tells us that there is a strong relationship between the granularity of a function unit under testing ...Reusing test cases from existing test case library is quite common in the software testing field. Testing practice tells us that there is a strong relationship between the granularity of a function unit under testing and that of the test case. A function unit with small granularity usually results in the test cases with the same small granularity. Therefore a test case defined as the function point,i. e.,the smallest size function unit,was provided for the first time.Though test cases with smaller granularity usually have better reusability,the cost of accurately reusing and integrating such test cases is also higher. In order to balance the test case reusability and the cost of test case reuse,a novel test case reuse model based on the function point was proposed in this paper. In this model,a reusable test case for specification-based testing was defined and some reuse strategies and three formal reuse methods were given. Finally,the complete automatic software process was realized by a reusing generation tool. The new method has improved reuse accuracy,while greatly enhances the software productivity.展开更多
Delta function is an important function in mathematics and physics. In this paper, the Laplace transforms of δ(t)and δ(t-τ)have been discussed in detail. After the Laplace transform of δ(t)is analyzed, the author ...Delta function is an important function in mathematics and physics. In this paper, the Laplace transforms of δ(t)and δ(t-τ)have been discussed in detail. After the Laplace transform of δ(t)is analyzed, the author has found that three aspects should be taken into account, i.e. τ→0+, τ→0- andτ=0; and it is the same with the Laplace transform of δ(t-τ). Then the results of the Laplace transform of Delta function have been obtained in a rigorous and comprehensive sense.展开更多
Halide perovskites have attracted tremendous attention as semiconducting materials for various optoelectronic applications.The functional metal-halide octahedral units and their spatial arrangements play a key role in...Halide perovskites have attracted tremendous attention as semiconducting materials for various optoelectronic applications.The functional metal-halide octahedral units and their spatial arrangements play a key role in the optoelectronic properties of these materials.At present,most of the efforts for material exploration focus on substituting the constituent elements of functional octahedral units,whereas designing the spatial arrangement of the functional units has received relatively little consideration.In this work,via a global structure search based on density functional theory(DFT),we discovered a metastable three-dimensional honeycomb-like perovskite structure with the functional octahedral units arranged through mixed edge-and comer-sharing.We experimentally confirmed that the honeycomb-like perovskite structure can be stabilized by divalent molecular cations with suitable size and shape,such as 2,2’-bisimidazole(BIM).DFT calculations and experimental characterizations revealed that the honeycomb-like perovskite with the formula of BIMPb2l6,synthesized through a solution process,exhibits high electronic dimensionality,a direct allowed bandgap of 2.1 eV,small effective masses for both electrons and holes,and high optical absorption coefficients,which indicates a significant potential for optoelectronic applications.The employed combination of DFT and experimental study provides an exemplary approach to explore prospective optoelectronic semiconductors via spatially arranging functional units.展开更多
In this paper three Banach spaces A(ф),A(ф)and A~1(ф)of functions holomor- phic in the unit ball B of ■~n are defined.We exhibit bounded projections from C(B)onto A(ф),from L~1(B)onto A~1(ф),and from L~∞(B)onto...In this paper three Banach spaces A(ф),A(ф)and A~1(ф)of functions holomor- phic in the unit ball B of ■~n are defined.We exhibit bounded projections from C(B)onto A(ф),from L~1(B)onto A~1(ф),and from L~∞(B)onto A(ф).Using these projections,we show that A(ф)~*≌A~1(ф)and A~1(ф)~*≌A(ф).展开更多
Isoindigo(IID)is widely used as organic dye and conjugated unit in opto-electronic materials.Functionalization of IID to increase its structural complexity is demanding for obtaining diversity properties.Herein,we dev...Isoindigo(IID)is widely used as organic dye and conjugated unit in opto-electronic materials.Functionalization of IID to increase its structural complexity is demanding for obtaining diversity properties.Herein,we developed a direct C-H/N-H activation method of IIDs via double alkyne annulations and synthesizedπ-extended IIDs with two pairs of 5/7 membered rings.The structure of theπ-extended IIDs was characterized and confirmed by^(1)H NMR,^(13)C NMR,HRMS and X ray crystal analysis.Their physical properties were characterized by UV-vis absorption,cyclic voltammetry and thermogravimetric analysis.The absorption coefficient of the annulated products enhanced significantly compared with the non-annulated analogue.展开更多
With the increasing advance of fifth generation(5G)network and the gradual expansion of digital devices,harsh working environment for electronic devices has spawned higher requirements for microwave absorbing material...With the increasing advance of fifth generation(5G)network and the gradual expansion of digital devices,harsh working environment for electronic devices has spawned higher requirements for microwave absorbing materials(MAMs).Since both the electromagnetic response and energy conversion character vary with temperature,to achieve temperature insensitive microwave absorption behaviour in wide temperature range has become extremely challenging.In this work,structured metacomposites containing sub-wavelength reduced graphene oxide(RGO)@carbon spheres were fabricated,and the microwave absorption was further improved through structural and composition design of the RGO@carbon units.Due to the unique anti-reflection effect on microwave of the metacomposites,the temperature-insensitive electromagnetic performance at elevated temperature could be exhibited.Moreover,both the dielectric relaxation behaviour and microwave absorption proformance of the system could be further increased.As a result,the effective absorption bandwidth(reflection loss(RL)<−10 dB)of the metacomposites with only 3.0 wt.%filler content could cover the entire X-band(8.2–12.4 GHz)frequency ranging from 298 to 473K.The metacomposite proposed in this work provides a“de-correlating”strategy to break the linkage between microwave absorption behaviour and temperature,which offers an interesting plateau for fabricating efficient high-temperature microwave absorption structures with tunable and designable advantages.展开更多
Serving as the interface between the fetal and maternal environments during gestation,the placenta plays critical roles in the protection of the developing fetus and the maintenance of maternal health.The placenta is ...Serving as the interface between the fetal and maternal environments during gestation,the placenta plays critical roles in the protection of the developing fetus and the maintenance of maternal health.The placenta is primarily derived from the embryonic trophectoderm which differentiates into various subtypes of trophoblast cells through villous and extravillous pathways.The interactions among trophoblasts and multiple decidual cells and immune cells at the maternal-fetal interface fundamentally form the functional units of the placenta,which are responsible for blood perfusion and maternal-fetal material exchange,immune tolerance,and the regulation of pregnancy adaptation.Defects in placental development and functional maintenance are in tight association with adverse pregnancy outcomes such as preeclampsia.In this article,we review recent advances on human trophoblast cell differentiation and the construction of placental functional units and discuss the placental and maternal factors that may contribute to the occurrence of preeclampsia.展开更多
Background Bryan cervical disc arthroplasty can be used to restore and maintain the mobility and function of the involved cervical spinal segments. The efficiency of posterior longitudinal ligament (PLL) resection i...Background Bryan cervical disc arthroplasty can be used to restore and maintain the mobility and function of the involved cervical spinal segments. The efficiency of posterior longitudinal ligament (PLL) resection in anterior cervical decompression and fusion has been demonstrated. However, no clinical reports have compared PLL removal with preservation in Bryan cervical disc arthroplasty. This study aimed to assess the role of removal of PLL in Bryan cervical disc arthroplasty at an 18-month follow-up.展开更多
A real continuous function which is defined on an interval is said to beA-convex if it is convex on the set of self-adjoint elements,with spectra in the interval,in all matrix algebras of the unital C-algebra A.We giv...A real continuous function which is defined on an interval is said to beA-convex if it is convex on the set of self-adjoint elements,with spectra in the interval,in all matrix algebras of the unital C-algebra A.We give a general formation of Jensen’s inequality for A-convex functions.展开更多
基金supported financially by the National Key R&D Program of China (Grant No. 2018YFB0104300)Beijing Natural Science Foundation (JQ19003, KZ201910005002 and L182009)+1 种基金National Natural Science Foundation of China (Grants 21875007, 51622202, and 21974007)the Project of Youth Talent Plan of Beijing Municipal Education Commission (CIT&TCD201804013)。
文摘Solid polymer electrolytes have been considered as the promising candidates to improve the safety and stability of high-energy lithium metal batteries.However,the practical applications of solid polymer electrolytes are still limited by the low ionic conductivity,poor interfacial contact with electrodes,narrow electrochemical window and weak mechanical strength.Here,a series of novel block copolymer electrolytes with three-dimensional networks are designed by cross-linked copolymerization of the polyethylene glycol soft segments and hexamethylene diisocyanate trimer hard segments.Their ionic migration performances and interface compatibilities with Li metal anode have been optimized delicately by tailoring the ratio of these functional units.The optimized block copolymer electrolyte has shown an amorphous crystalline structure,a high ionic conductivity of ~5.7×10^(-4)S cm^(-1),high lithium ion transference number(~0.49),wide electrochemical window up to ~4.65 V(vs.Li+/Li) and favorable mechanical strength at 55℃.Furthermore,the enhanced interface compatibility can well support the normal operations of lithium metal batteries using both LiFePO4 and LiNi0.8Co0.15Al0.05O2 cathodes.This study not only paves a new way to develop solid polymer electrolyte with optimizing functional units,but also provides a polymer electrolyte design strategy for the application demand of lithium metal battery.
基金supported by the National Natural Science Foundation of China(Nos.21203008,21975025,12274025)the Hainan Province Science and Technology Special Fund(Nos.ZDYF2021SHFZ232,ZDYF2023GXJS022)the Hainan Province Postdoctoral Science Foundation(No.300333)。
文摘The sulfide-based solid-state electrolytes(SEs)reactivity toward moisture and Li-metal are huge barriers that impede their large-scale manufactu ring and applications in all-solid-state lithium batteries(ASSLBs).Herein,we proposed an Al and O dual-doped strategy for Li_(3)PS_(4)SE to regulate the chemical/electrochemical stability of anionic PS_(4)^(3-)tetrahedra to mitigate structural hydrolysis and parasitic reactions at the SE/Li interface.The optimized Li_(3.08)A_(10.04)P_(0.96)S_(3.92)O_(0.08)SE presents the highestσLi+of 3.27 mS cm^(-1),which is~6.8 times higher than the pristine Li_(3)PS_(4)and excellently inhibits the structural hydrolysis for~25 min@25%humidity at RT.DFT calculations confirmed that the enhanced chemical stability was revealed to the intrinsically stable entities,e.g.,POS33-units.Moreover,Li_(3.08)Al_(0.04)P_(0.96)S_(3.92)O_(0.08)SE cycled stably in Li//Li symmetric cell over 1000 h@0.1 mA cm^(-2)/0.1 mA h cm^(-2),could be revealed to Li-Al alloy and Li_(2)Oat SE/Li interface impeding the growth of Li-dendrites during cycling.Resultantly,LNO@LCO/Li_(3.08)Al_(0.04)P_(0.96)S_(3.92)O_(0.08)/Li-In cell delivered initial discharge capacities of 129.8 mA h g^(-1)and 83.74%capacity retention over 300 cycles@0.2 C at RT.Moreover,the Li_(3.08)Al_(0.04)P_(0.96)S_(3.92)O_(0.08)SE presented>90%capacity retention over 200 and 300 cycles when the cell was tested with LiNi_(0.8)Co_(0.15)Al_(0.05)O_(2)(NCA)cathode material vs.5 and 10 mg cm^(-2)@RT.
文摘Urban land use is always the central focus of urban planners and policymakers when pursuing urban sustainable development.Currently,many studies have explored urban land use using satellite data,but few of them can identify the social function of land use through these data.In this research,OpenStreetMap(OSM)data are used to extract urban land use social functional units.Firstly,the OSM data are transferred to actual land use types based on the established mapping rules between OSM data and the urban land use classification standards.Then,the improved DBSCAN algorithm is applied with OSM data of the study area after estimating the parameters of the neighborhood radius(Eps)and the minimum polygons(MinPolys)based on the polygon density.With the two estimated parameters,the improved DBSCAN algorithm is used to cluster residential,commercial and public service land use social functional polygons of the OSM data.Following that,the clusters of the three land use types are processed into land use social functional units.The results show that OSM data perform well in determining these three land use social functional clusters using the improved DBSCAN algorithm,and the social functional units display obvious spatial features.
文摘In this paper we obtained the asymptotic formula of the orthogonal rational function on the unit circle with respect to the weight function μ(z) with preasigned poles, which are in the exterior of the unit disk.
基金financially supported by the National Key R&D Program of China (2022YFB2404400)the National Natural Science Foundation of China (92263206,and 22002004)“The Youth Beijing Scholars program” (PXM2021_014204_000023)。
文摘LiMn_(6) hexatomic-rings act as functional units in Li-rich layered oxides(LLOs),which determine the capacity,voltage,and structural stability of LLOs.However,the symmetry of the LiMn_(6) hexatomic-ring is always broken,especially in the grain surface of LLOs,which will greatly affect its electrochemical performance.Herein,the symmetry-breaking of LiMn_(6) hexatomic-ring in the grain surface of Li_(2)MnO_(3) was studied,and their effect on charge compensation mechanism and structure evolution behavior was thoroughly investigated.The results show that the electrochemical activity of the symmetry-broken LiMn_(6) hexatomic-ring is higher than that of the unbroken LiMn_(6),and the former is more favorable for spinelization on the grain surface.Furthermore,the exposure proportion of crystallographic planes with different symmetry-broken LiMn_(6) hexatomic-ring has also been discussed,which can be adjusted by changing the partial pressure of oxygen.The in-depth understanding of the symmetry-breaking of LiMn_(6) hexatomic-ring will provide more targeted strategies for designing high-performance LLOs cathodes for lithium-ion batteries.
基金supported by Shanghai Cooperation Organization Science and Technology Partnership Program(2020E01039)the Scientific Instrument Developing Project,CAS(YJKYYQ20210033)+3 种基金CAS Youth Interdisciplinary Team(JCTD-2021–18)the West Light Foundation of CAS(2021-XBQNXZ-004)the Outstanding Youth Science Fund Project of Natural Science Foundation of Xinjiang(2022D01E90)Key Training Object of Talent Project of Urumqi。
文摘As a fundamental parameter of the optical crystals,birefringence plays a vital role in many optical applications,such as phase modulation,light splitting,and polarization,especially the phase matching process of the nonlinear optical crystals.The big birefringence not only benefits to the miniaturization of related devices,but also broadens the phase-matching wavelength range of nonlinear optical crystals.The design and synthesis of crystals with large birefringence becomes a hot research topic due to its more and more important applications in the optical modulation and laser technology fields.Herein,crystals with birefringence greater than 0.05 in the borate system are reviewed and classified according to different birefringent active groups,and the relationship between structure and properties is thoroughly explored.It is hoped that this review will provide a clear understanding of what kinds of building units and arrangements would have more opportunity to get adequate birefringence in borate systems and provide the statistical references to encourage the emergence of better crystal materials with large birefringence.
文摘Based on a questionnaire survey,the paper made a comparative study on the changes of traditional library positions within the context of the emerging professional positions and functional units at some large academic libraries in China and in the United States from 1998 to 2007.It describes how some of the library professional positions and functional units have gone through a time period of intensified and proactive position allocation realignment in terms of their rise,decline,fission and/or fusion within the administrative context of their library's evolving changes in missions,objectives and service delivery structure under the impact of the rapid development of information technologies.Such changes are graphically demonstrated in several charts in this paper to highlight the evolutionary development of academic librarianship in general and the waves of changes for library position reallocations in specific in the ten-year period under study.It is believed that such a study can be useful for discerning the overall developing trend of academic librarianship,especially in the area of the rising professional and social status of academic librarianship during this period.The movement of library position allocation realignment was a corresponding response at the time to the influx of applicable information technologies to the library scene.It not only made the library operation to become'leaner and meaner,' but also gave added impetus to the rise of the professional and social status of their practitioners in the society due to the latter's enhanced service delivery innovations and capabilities for meeting their constituencies' timely information needs more satisfactorily.
文摘Aim The objective of this study was to analyze the oral health among Japanese adults, with and without diabetes mellitus. Methodology The subjects were 518 community residents aged 20 to 91 years in Japan, who participated in the "Akita health and nutrition survey" and the "Akita dental disease survey", conducted in 2006. The surveys comprised a self-administered questionnaire, along with medical and dental examinations. Results Using the community periodontal index (CPI), the mean numbers of sextants presenting codes 0, 1 and 2 were significantly lower in diabetics than non-diabetics among the 59 years or younger age group. Although the mean numbers of sextants with codes 0, 1 and 2 among the 60 to 69 years age group were lower, and sextants with a code X among the 59 years or younger age group were higher in diabetics than non-diabetics, no statistically significant differences were detected. The tendency of lower mean numbers of natural teeth and functional tooth units in diabetics than non-diabetics was observed, however no differences were statistically significant. Conclusion The outcome of periodontal disease seemed to be influenced by the diabetic state to some degree, but a clear association between diabetes and oral health status was not found.
文摘By means of Delta-function & unit step function to express the force of solid particle on plane inertial shaker's screen, an mathematical model of the differential equation type was set up and solved. According to analysis of the solution, the relation is given between the throw period & displacement with the parameters of shaker design & solid particle. The method of numerical value calculation & analysis for the relation is given too.
基金National Natural Science Foundation of China(No.61262010)
文摘Reusing test cases from existing test case library is quite common in the software testing field. Testing practice tells us that there is a strong relationship between the granularity of a function unit under testing and that of the test case. A function unit with small granularity usually results in the test cases with the same small granularity. Therefore a test case defined as the function point,i. e.,the smallest size function unit,was provided for the first time.Though test cases with smaller granularity usually have better reusability,the cost of accurately reusing and integrating such test cases is also higher. In order to balance the test case reusability and the cost of test case reuse,a novel test case reuse model based on the function point was proposed in this paper. In this model,a reusable test case for specification-based testing was defined and some reuse strategies and three formal reuse methods were given. Finally,the complete automatic software process was realized by a reusing generation tool. The new method has improved reuse accuracy,while greatly enhances the software productivity.
基金Funded by by Natural Science Foundation Project of CQ CSTC (Grant No: cstc2012jjA50018)the Basic Research of Chongqing Municipal Education Commission (Grant No:KJ120613)
文摘Delta function is an important function in mathematics and physics. In this paper, the Laplace transforms of δ(t)and δ(t-τ)have been discussed in detail. After the Laplace transform of δ(t)is analyzed, the author has found that three aspects should be taken into account, i.e. τ→0+, τ→0- andτ=0; and it is the same with the Laplace transform of δ(t-τ). Then the results of the Laplace transform of Delta function have been obtained in a rigorous and comprehensive sense.
基金the National Natural Science Foundation of China (NSFC) (Grant No. 51972130)Startup Fund of Huazhong University of Science and Technology, and Director Fund of Wuhan National Laboratory for Optoelectronics.
文摘Halide perovskites have attracted tremendous attention as semiconducting materials for various optoelectronic applications.The functional metal-halide octahedral units and their spatial arrangements play a key role in the optoelectronic properties of these materials.At present,most of the efforts for material exploration focus on substituting the constituent elements of functional octahedral units,whereas designing the spatial arrangement of the functional units has received relatively little consideration.In this work,via a global structure search based on density functional theory(DFT),we discovered a metastable three-dimensional honeycomb-like perovskite structure with the functional octahedral units arranged through mixed edge-and comer-sharing.We experimentally confirmed that the honeycomb-like perovskite structure can be stabilized by divalent molecular cations with suitable size and shape,such as 2,2’-bisimidazole(BIM).DFT calculations and experimental characterizations revealed that the honeycomb-like perovskite with the formula of BIMPb2l6,synthesized through a solution process,exhibits high electronic dimensionality,a direct allowed bandgap of 2.1 eV,small effective masses for both electrons and holes,and high optical absorption coefficients,which indicates a significant potential for optoelectronic applications.The employed combination of DFT and experimental study provides an exemplary approach to explore prospective optoelectronic semiconductors via spatially arranging functional units.
基金Supported in part by the National Natural Science Foundation of China.
文摘In this paper three Banach spaces A(ф),A(ф)and A~1(ф)of functions holomor- phic in the unit ball B of ■~n are defined.We exhibit bounded projections from C(B)onto A(ф),from L~1(B)onto A~1(ф),and from L~∞(B)onto A(ф).Using these projections,we show that A(ф)~*≌A~1(ф)and A~1(ф)~*≌A(ф).
基金This work is supported by the NSFC(Nos.22071254,21790363,22021002,22090021,22171245)X.-S.Zhang is grateful for the funding from Youth Innovation Promotion Association CAs(No.2021032)+1 种基金This work is also supported by the Key Research Program of the Chinese Academy of Sciences(Grant No.121111KYSB20200022)the CAS-Croucher Funding Scheme for Joint Laboratories.
文摘Isoindigo(IID)is widely used as organic dye and conjugated unit in opto-electronic materials.Functionalization of IID to increase its structural complexity is demanding for obtaining diversity properties.Herein,we developed a direct C-H/N-H activation method of IIDs via double alkyne annulations and synthesizedπ-extended IIDs with two pairs of 5/7 membered rings.The structure of theπ-extended IIDs was characterized and confirmed by^(1)H NMR,^(13)C NMR,HRMS and X ray crystal analysis.Their physical properties were characterized by UV-vis absorption,cyclic voltammetry and thermogravimetric analysis.The absorption coefficient of the annulated products enhanced significantly compared with the non-annulated analogue.
基金the National Natural Science Foundation of China(Nos.U1704253 and 21671057).
文摘With the increasing advance of fifth generation(5G)network and the gradual expansion of digital devices,harsh working environment for electronic devices has spawned higher requirements for microwave absorbing materials(MAMs).Since both the electromagnetic response and energy conversion character vary with temperature,to achieve temperature insensitive microwave absorption behaviour in wide temperature range has become extremely challenging.In this work,structured metacomposites containing sub-wavelength reduced graphene oxide(RGO)@carbon spheres were fabricated,and the microwave absorption was further improved through structural and composition design of the RGO@carbon units.Due to the unique anti-reflection effect on microwave of the metacomposites,the temperature-insensitive electromagnetic performance at elevated temperature could be exhibited.Moreover,both the dielectric relaxation behaviour and microwave absorption proformance of the system could be further increased.As a result,the effective absorption bandwidth(reflection loss(RL)<−10 dB)of the metacomposites with only 3.0 wt.%filler content could cover the entire X-band(8.2–12.4 GHz)frequency ranging from 298 to 473K.The metacomposite proposed in this work provides a“de-correlating”strategy to break the linkage between microwave absorption behaviour and temperature,which offers an interesting plateau for fabricating efficient high-temperature microwave absorption structures with tunable and designable advantages.
基金supported by grants from the National Key Research and Development Program of China(2018YFC1004100 to YLW)the National Natural Sciences Foundation(81730040 to YLW and 32171115 and 31800986 to XS)。
文摘Serving as the interface between the fetal and maternal environments during gestation,the placenta plays critical roles in the protection of the developing fetus and the maintenance of maternal health.The placenta is primarily derived from the embryonic trophectoderm which differentiates into various subtypes of trophoblast cells through villous and extravillous pathways.The interactions among trophoblasts and multiple decidual cells and immune cells at the maternal-fetal interface fundamentally form the functional units of the placenta,which are responsible for blood perfusion and maternal-fetal material exchange,immune tolerance,and the regulation of pregnancy adaptation.Defects in placental development and functional maintenance are in tight association with adverse pregnancy outcomes such as preeclampsia.In this article,we review recent advances on human trophoblast cell differentiation and the construction of placental functional units and discuss the placental and maternal factors that may contribute to the occurrence of preeclampsia.
文摘Background Bryan cervical disc arthroplasty can be used to restore and maintain the mobility and function of the involved cervical spinal segments. The efficiency of posterior longitudinal ligament (PLL) resection in anterior cervical decompression and fusion has been demonstrated. However, no clinical reports have compared PLL removal with preservation in Bryan cervical disc arthroplasty. This study aimed to assess the role of removal of PLL in Bryan cervical disc arthroplasty at an 18-month follow-up.
基金Supported by Shanghai Leading Academic Discipline Project(Grant No.B407)National Natural Science Foundation of China(Grant No.11171109)
文摘A real continuous function which is defined on an interval is said to beA-convex if it is convex on the set of self-adjoint elements,with spectra in the interval,in all matrix algebras of the unital C-algebra A.We give a general formation of Jensen’s inequality for A-convex functions.