This study aimed to develop original laboratory culture and sediment toxicity testing protocols for the freshwater gastropod Bellamya aeruginosa （Reeve）, a new potential species for sediment toxicity testing. B. aer...This study aimed to develop original laboratory culture and sediment toxicity testing protocols for the freshwater gastropod Bellamya aeruginosa （Reeve）, a new potential species for sediment toxicity testing. B. aeruginosa was successfully cultured with an effective culture system under proposed laboratory conditions. Optimal ad libitum feeding levels for larvae, juveniles, and adults were 2.0, 6.0, and 16.0 mg fish food/（snall.day）, respectively. Mean survival rates of juveniles were higher than 90%, The snails could be sexed at 9 weeks of age, and their generation time is approximately 4 months. Reproduction continued all year around; the mean fecundity was 0.55 newborn/（female.day）. The utility of this species for bioassays was evaluated in both 10-day and 28-day case studies with artificial sediments. The 10-day LC50 of Cu for larvae was 480 μg/g dry weight （dw）, and the lowest observed effects concentration of Cu for survival and growth of larvae was 195 μg/g dw. Survival and growth are reliable indicators of acute toxicity. Larvae accumulated more Cu than adults. B. aeruginosa exhibited a higher sensitivity to Cu exposure than standard test species （Hyalella azteca and Chironomus tentans）. The 28-day test of sediment toxicity with adults showed that fecundity was a robust endpoint indicator of reproductive toxicity, and the biochemical endpoints of superoxide dismutase, catalase, and glutathione could be used as sensitive biomarkers for Cu-induced oxidative damage. B. aeruginosa can be therefore recommended as a candidate for the standardization of the freshwater sediment toxicity test protocol.展开更多
Imide-based conjugated molecules have emerged as a highly promising class of building blocks for constructing n-type semiconducting materials with lowlying lowest unoccupied molecular orbitals and exceptional stabilit...Imide-based conjugated molecules have emerged as a highly promising class of building blocks for constructing n-type semiconducting materials with lowlying lowest unoccupied molecular orbitals and exceptional stability.Although imides,such as naphthalene diimides,perylene diimides and their lateral fused analogs,have been synthesized extensively,the design and synthesis of largerπ-extended molecules incorporating more than two imide groups are desirable but still very challenging.Herein,we report the synthesis of an unprecedented electron-deficient bisanthene tetraimide(ATI)containing a bisantheneconjugated core and four five-membered imide groups,which was successfully achieved via a combined approach of solution and on-surface synthesis.The chemical structures,electronic states,formation mechanism and aromaticity of ATI were systematically investigated by scanning tunneling microscopy,noncontact atomic force microscopy,scanning tunneling spectroscopy,and density functional theory calculations.展开更多
In organic solar cells(OSCs),it is an effective way to improve the power conversion efficiency(PCE)by adding a guest component with appropriate absorption and energy levels in the host system.Herein,a new nonfullerene...In organic solar cells(OSCs),it is an effective way to improve the power conversion efficiency(PCE)by adding a guest component with appropriate absorption and energy levels in the host system.Herein,a new nonfullerene acceptor(NFA)named TBF-2Cl was developed by the strategy of expanding theπconjugated core of 2,2’-(((4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b’]dithiophene-2,7-diyl)bis(methaneylylidene))bis(5,6-dichloro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile(IDT-4Cl)with two benzene rings.With increase of benzene units,TBF-2Cl exhibits higher lowest unoccupied molecular orbital(LUMO)level of-3.75 eV than that of one benzene unit based NFA IDT-4Cl and fluorene core based NFA F-2Cl,which facilitates enhancing the open-circuit voltage(V_(oc))of ternary devices.Moreover,TBF-2Cl film shows a medium optical bandgap with the absorption range from 500-800 nm,being well complementary with the wide bandgap polymer donor D18 and narrow bandgap NFA CH-6F.Accordingly,a remarkable PCE of 18.92%with a high short-circuit current density(J_(sc))of 27.40 mA·cm^(-2),a fill factor(FF)of 0.749,especially an outstanding V_(oc) of 0.922 V was achieved for the optimal ternary device based on D18:TBF-2Cl:CH-6F,surpassing the binary counterpart(17.08%).The findings provide insight into the development of new guest acceptors for obtaining more efficient OSCs.展开更多
Sodium-ion batteries are promising for large-scale energy storage due to sodium's low cost and infinite abundance. The most popular cathodes for sodium-ion batteries, i.e., the layered sodium-containing oxides, us...Sodium-ion batteries are promising for large-scale energy storage due to sodium's low cost and infinite abundance. The most popular cathodes for sodium-ion batteries, i.e., the layered sodium-containing oxides, usually exhibit reversible host rearrangement between P-type and O-type stacking upon charge/discharge. Herein we demonstrate that such host rearrangement is unfavorable and can be suppressed by introducing transition-metal ions into sodium layers. The electrode with stabilized P3-type stacking delivers superior rate capability, high energy efficiency, and excellent cycling performance. Owing to the cation-mixing nature, it performs the lowest lattice strain among all reported cathodes for sodium-ion batteries. Our findings highlight the significance of a stable host for sodium-ion storage and moreover underline the fundamental distinction in material design strategy between lithium-and sodium-ion batteries.展开更多
The nesting problem involves arranging pieces on a plate to maximize use of material. A new scheme for 2D ir- regular-shaped nesting problem is proposed. The new scheme is based on the NFP (No Fit Polygon) algorithm a...The nesting problem involves arranging pieces on a plate to maximize use of material. A new scheme for 2D ir- regular-shaped nesting problem is proposed. The new scheme is based on the NFP (No Fit Polygon) algorithm and a new placement principle for pieces. The novel placement principle is to place a piece to the position with lowest gravity center based on NFP. In addition, genetic algorithm (GA) is adopted to find an efficient nesting sequence. The proposed scheme can deal with pieces with arbitrary rotation and containing region with holes, and achieves competitive results in experiment on benchmark datasets.展开更多
Variable thicknesses in the lowest half-ηmodel level （LML） are often used in atmospheric models to compute surface diagnostic fields such as surface latent and sensible heat fluxes.The effects of the LML on simulat...Variable thicknesses in the lowest half-ηmodel level （LML） are often used in atmospheric models to compute surface diagnostic fields such as surface latent and sensible heat fluxes.The effects of the LML on simulated tropical cyclone （TC）evolution were investigated in this study using the Weather Research and Forecasting （WRF） model.The results demonstrated notable influences of the LML on TC evolution when the LML was placed below 12 m.The TC intensification rate decreased progressively with a lowering of the LML,but its ultimate intensity change was relatively small.The maximum 10-m winds showed different behavior to minimum sea level pressure and azimuthally-averaged tangential winds,and thus the windpressure relationship was changed accordingly by varying the LML.The TC circulation was more contracted in association with a higher LML.Surface latent heat fluxes were enhanced greatly by elevating the LML,wherein the wind speed at the LML played a dominant role.The changes in the wind speed at the LML were dependent not only on their profile differences,but also the different heights they were taken from.Due to the enhanced surface heat fluxes,more intense latent heat release occurred in the eyewall,which boosted the storm＇s intensification.A higher LML tended to produce a stronger storm,and therefore the surface friction was reinforced,which in turn induced stronger boundary layer inflow together with increased diabatic heating.展开更多
A friction stir welding window was developed for effective joining of AA2219 aluminium alloy. Joints were fabricated using different combination of process parameters such as rotational speed and welding speed. Based ...A friction stir welding window was developed for effective joining of AA2219 aluminium alloy. Joints were fabricated using different combination of process parameters such as rotational speed and welding speed. Based on macrostructural analysis, the friction stir welding window was constructed. The strength values of joints at different regions of friction stir welding window were analyzed using tensile properties, microstructural studies, and the fracture location of joints was correlated with the lowest hardness distribution profiles. These windows will act as reference maps for selecting appropriate friction stir welding process parameters to get good quality welds of AA2219 aluminium alloys.展开更多
Understanding what environmental factors are genetically linked to a phenologic al event is critical for predicting responses to climate change.Photo synthetic phenology often varies among a species of evergreen conif...Understanding what environmental factors are genetically linked to a phenologic al event is critical for predicting responses to climate change.Photo synthetic phenology often varies among a species of evergreen conifers due to local adaptation.However,few empirical studies have revealed relevant relationships between climatic factors in provenance environments and photosynthetic phenology.This study evaluated the effects of environmental conditions of the growing site and seed source provenance on the seasonal changes in maximal photochemical quantum yield of photo systemⅡ(Fv/Fm)in a common garden experiment with 2-year-old seedlings of Sakhalin fir(Abies sachalinensis),a representative species with local adaptation,from four seed source provenances.A logistic model was constructed to explain the seasonal variation of Fv/Fmfrom July to October and the relationships between the estimated model parameters and representative factors featuring provenance environments were evaluated.The landscape gradient of the detected model parameters responsible for the provenance environments was visualized in a map of the distribution area.The lowest temperature was the most plausible factor in the growing environment to explain the seasonal changes of Fv/Fm.Among the representative meteorological factors of provenance environments,the lowest temperatures in July showed significant relationships with two model parameters,explaining the lower limit of Fv/Fmand the higher sensitivity of autumn Fv/Fmdecline.The estimated spatial maps of model parameters consistently showed that the higher the lowest temperature in July in the provenance environment,the lower the Fv/Fmin October and the greater the decrease in the autumn Fv/Fmdecline.Therefore,the lowest summer temperature could be associated with the local adaptation of autumn photosynthetic phenology in A.sachalinensis.展开更多
Organic cathodes for alkali-metal-ion batteries attract great attentions in recent years,but the ion storage sites are limited to some finite functional groups.This is because an organic cathode must have proper lowes...Organic cathodes for alkali-metal-ion batteries attract great attentions in recent years,but the ion storage sites are limited to some finite functional groups.This is because an organic cathode must have proper lowest unoccupied molecular orbitals(LUMO) to accept electrons at high potential.Herein,a novel type of organophosphate-based cathode has successfully been explored by tuning the LUMO energy level of organophosphates through metal ions with an inert electron pair.For the first time,the P=O of phytate(PA),N,N,N’,N’-ethylenediaminetetrakis(methylene phytate)(EDTMP),and diethylenetriaminepentakis(methyl phytate)(DTPMP) is activated by lead/bismuth(with 6s2electron pair) to storage Li/Na/K ions reversibly.Typically,density functional theory calculations indicate that the LUMO energy of Bi-PA is greatly reduced from-0.99(PA) to-4.61 eV,which shows the first discharge capacity of 173,182 and 206mAh·g-1and the reversibly capacity of 102,102 and 101mAh·g-1with the discharge platform of 2.4,2.1 and 2.4 V for Li/Na/K-ion battery cathodes,respectively.Similarly,with proper LUMO energy level,Pb-PA(-4.63 eV),Pb-EDTMP(-3.71 eV),and Pb-DTPMP(-4.45 eV) all exhibit admirable performance.This unique strategy of organic materials to alkali-metal-ion battery cathodes offers a new avenue for future energy storage systems.展开更多
One novel two-dimensional(2D)terbium-based framework[Tb(L2-)(Ac)(DMA)]n(1)(H2 L=4’-(3,5-dicarboxyphenyl)-4,2’:6’,4"-terpyridine)was successfully isolated and structurally characterized.The structural analysis ...One novel two-dimensional(2D)terbium-based framework[Tb(L2-)(Ac)(DMA)]n(1)(H2 L=4’-(3,5-dicarboxyphenyl)-4,2’:6’,4"-terpyridine)was successfully isolated and structurally characterized.The structural analysis reveals that two Tb3+ions in 1 are bridged by twoη1:η1:μ2 carboxylates from L2-to form a binuclear unit,which is further linked by L2-to generate a 2D layer with kgd topology.Moreover,1 displays excellent thermostability and extensive solvent stability.Luminescent measurements reveal that 1 can be used as a recyclable luminescent probe for detecting pyridine with the lowest detection lim it of 0.12 vol%,and the luminescent mechanism is also discussed.展开更多
Global uniform chart datum(CD)surface construction is the basic upon which to realize various vertical datums transformation,and is of great importance for geospatial data expression under the same vertical datum.Gene...Global uniform chart datum(CD)surface construction is the basic upon which to realize various vertical datums transformation,and is of great importance for geospatial data expression under the same vertical datum.Generally,the CD level is computed by developing the function between tidal constituents’harmonic constants and time,i.e.,the lowest astronomical tide is taken as the lowest predicted tide level by adopting the major constituents over a 19-a period.The CD surface prescribed in China is the theoretical lowest tide(TLT)and is calculated using 13 tidal constituents,i.e.,short-period(Q_(1),O_(1),P_(1),K_(1),N_(2),M_(2),S_(2),K_(2),M_(4),MS_(4)and M_(6))and long-period(Sa and Ssa)tidal constituents.Although the accuracy in determining short-period tidal constituents has improved gradually,the long-period tide has not been studied thoroughly owing to nonstationary and temporal variations.Previous studies have intended to evaluate the effect of Sa and Ssa tides in the determination of the TLT level for the purpose of determining a more accurate CD surface for the China seas and adjacent waters.Here,the parameters of long-period tidal correction and long-period tidal correction rate were treated as the effect of both Sa and Ssa on the TLT,and the TOPEX/Poseidon and Jason series satellite altimetry data ranged from October 1992 to April 2022 were adopted to analyze the contribution of long-period tidal constituents.Results showed that the average long-period correction value is 10.10 cm(range from 8.57 cm to 14.98 cm),and that the average long-period tidal contribution rate is 14.56%(range from 9.09%to 23.97%)in the China seas and adjacent waters.Finally,data from 82 tide gauge station with at least a 1-a record of hourly observations were compared with satellite-derived result.We concluded that the long-period tidal contribution should not be neglected in TLT construction.Furthermore,to reduce tidal datum uncertainty,accurate extraction of long-period tidal constituents should receive closer attentions.展开更多
Objective One of major challenges in paleoenvironmental reconstruction using travertine in the Huanglong area is whether one can accurately determinate the age of travertine through high-precision and high-resolution...Objective One of major challenges in paleoenvironmental reconstruction using travertine in the Huanglong area is whether one can accurately determinate the age of travertine through high-precision and high-resolution dating techniques. Previous works of 14C or ESR chronology, however, have shown that the variation of deposition ages of travertine was displayed inconsistent with each other even conflict. For instance, （1） The oldest travertine age （80 ka） located in the middle of this travertine succession is departure from sequential deposition; （2） Top or boundary ages in this sedimentary section, even with the same dating method （14C）, are three times errors, moreover, the age of the depositional sequence is not continuous. We report here the U230Th ages in lowest boundary of travertine in Dawanzhangjia Valley, Huanglong, China, to discuss the effectiveness of U-series dating for cold-water travertine and the significance of age for vicissitude of paleoenvironment.展开更多
The procurement of public construction projects must walk a fine line between the corruption of state officials and collusion of contractors. The method of awarding projects to the lowest responsible tenderer was orig...The procurement of public construction projects must walk a fine line between the corruption of state officials and collusion of contractors. The method of awarding projects to the lowest responsible tenderer was originally implemented to guard against corruption of state officials. However, an investigation of the construction industry in the Canadian province of Quebec showed that lowest-tender-offer procurement gave rise to collusion of companies tendering for the contracts. Alternatively, bestvalue procurement has been used for decades, but here problems arise owing to the necessity of subjective judging of measures other than price to compare bids, giving rise to time-and money-consuming protests. The paper proposes a compelling argument that the construction engineering management(CEM) culture should refocus its efforts on enhancing project cost certainty rather than merely searching for means to design a project in a manner that produces the lowest initial cost, and awards the construction to the lowest tender offer that focuses on cost savings during the project development and delivery process. The difference in the two approaches is subtle but extremely important. To make the transition, the engineering management tools must be advanced to the next level.This means that all project control tools for managing cost,schedule, and technical scope must be transformed from working in the deterministic mode to the stochastic mode,thus making the probability of completing the projectwithin or below its official budget the primary decision criterion. To do so, CEMs must accept that there is a benefit in paying more for an alternative that increases cost certainty for the entire project. The authors of this paper hope that it will provide the grist for a more general dialog across all industry sectors where engineering management is practiced.展开更多
The convergences ununiformly and uniformly are established for the nonconforming finite element methods for the second order elliptic problem with the lowest regularity, i.e., in the case that the solution u is an ele...The convergences ununiformly and uniformly are established for the nonconforming finite element methods for the second order elliptic problem with the lowest regularity, i.e., in the case that the solution u is an element of H-0(1)(Omega) only.展开更多
A two-level stabilized finite element method for the Stokes eigenvalue problem based on the local Gauss integration is considered. This method involves solving a Stokes eigenvalue problem on a coarse mesh with mesh si...A two-level stabilized finite element method for the Stokes eigenvalue problem based on the local Gauss integration is considered. This method involves solving a Stokes eigenvalue problem on a coarse mesh with mesh size H and a Stokes problem on a fine mesh with mesh size h -- O（H2）, which can still maintain the asymptotically optimal accuracy. It provides an approximate solution with the convergence rate of the same order as the usual stabilized finite element solution, which involves solving a Stokes eigenvalue problem on a fine mesh with mesh size h. Hence, the two-level stabilized finite element method can save a large amount of computational time. Moreover, numerical tests confirm the theoretical results of the present method.展开更多
In the strong uniform magnetic field, the noncommutative plane （NCP） caused by the lowest Landau level （LLL） effect, and QED with NCP （QED-NCP） are studied. Being similar to the condensed matter theory of quantu...In the strong uniform magnetic field, the noncommutative plane （NCP） caused by the lowest Landau level （LLL） effect, and QED with NCP （QED-NCP） are studied. Being similar to the condensed matter theory of quantum Hall effect, an effective filling factor f（B） is introduced to characterize the possibility that the electrons stay on the LLL. The analytic and numerical results of the differential cross section for the process of backward Compton scattering in accelerator with unpolarized or polarized initial photons are calculated. The existing data of BL38B2 in Spring-8 have been analyzed roughly and compared with the numerical predictions primitively. We propose a precise measurement of the differential cross sections of backward Compton scattering in a strong perpendicular magnetic field, which may reveal the effects of NCP.展开更多
This paper studies the reliability evaluation of a stochastic manufacturing system with multiple production lines in parallel. Multiple repairs and different failure rates, never simultaneously addressed in earlier wo...This paper studies the reliability evaluation of a stochastic manufacturing system with multiple production lines in parallel. Multiple repairs and different failure rates, never simultaneously addressed in earlier works, are taken into account. First, a revised graphical methodology integrating transformation and decomposition is utilized to construct the stochastic manufacturing system as a multi-state manufacturing network （MSMN）. In particular, a ＂predecessor-set＂ technique is proposed to deal with multiple repairs. An algorithm is proposed to generate the lowest capacity vectors （LCVs） that stations should provide to satisfy the workloads. Subsequently, the system reliability of the MSMN, which is defined as the probability of demand satisfaction, is calculated in terms of the LCVs. A real case of a printed circuit board manufacturing system is utilized to demonstrate how the system reliability can be evaluated. A further decision making issue is addressed based on the derived system reliability.展开更多
Orifice plate energy dissipater as well as plug energy dissipater, as a kind of effective energy dissipater with characteristics of simple structure, convenient construction and high energy dissipation ratio, has beco...Orifice plate energy dissipater as well as plug energy dissipater, as a kind of effective energy dissipater with characteristics of simple structure, convenient construction and high energy dissipation ratio, has become welcomed more and more by hydraulics researchers. The two kinds of energy dissipaters with sudden reduction and sudden enlargement forms are similar in energy dissipation mechanism, but there are differences in energy dissipation characteristics and cavitation characteristics. In the present paper, the differences between orifice plate and plug in energy loss coefficient, relating to their energy dissipation ratio, in the backflow region length, relating to their energy loss coefficient, and in the lowest wall pressure coefficient, relating to their cavitations risk, were analyzed by numerical simulations and physical experiment, and their features in above three aspects were also revealed. The results of research in the present paper demonstrate that the backflow region length of orifice plate is longer than that of plug at the same contraction ratio, the lowest wall pressure coefficient of plug is smaller than that of orifice plate at the same contraction ratio, and the energy loss coefficient of orifice plate is bigger than that of plug, which illustrates that plug is superior to orifice plate in resistance cavitation damage at the same contraction ratio.展开更多
基金supported by the National Natural Science Foundation of China (No.20677021)the Science Foundation of Jishou University (No.jsdxkyzz200101)
文摘This study aimed to develop original laboratory culture and sediment toxicity testing protocols for the freshwater gastropod Bellamya aeruginosa （Reeve）, a new potential species for sediment toxicity testing. B. aeruginosa was successfully cultured with an effective culture system under proposed laboratory conditions. Optimal ad libitum feeding levels for larvae, juveniles, and adults were 2.0, 6.0, and 16.0 mg fish food/（snall.day）, respectively. Mean survival rates of juveniles were higher than 90%, The snails could be sexed at 9 weeks of age, and their generation time is approximately 4 months. Reproduction continued all year around; the mean fecundity was 0.55 newborn/（female.day）. The utility of this species for bioassays was evaluated in both 10-day and 28-day case studies with artificial sediments. The 10-day LC50 of Cu for larvae was 480 μg/g dry weight （dw）, and the lowest observed effects concentration of Cu for survival and growth of larvae was 195 μg/g dw. Survival and growth are reliable indicators of acute toxicity. Larvae accumulated more Cu than adults. B. aeruginosa exhibited a higher sensitivity to Cu exposure than standard test species （Hyalella azteca and Chironomus tentans）. The 28-day test of sediment toxicity with adults showed that fecundity was a robust endpoint indicator of reproductive toxicity, and the biochemical endpoints of superoxide dismutase, catalase, and glutathione could be used as sensitive biomarkers for Cu-induced oxidative damage. B. aeruginosa can be therefore recommended as a candidate for the standardization of the freshwater sediment toxicity test protocol.
基金support from the National Natural Science Foundation of China(grant nos.22161132026,21790053,51821002,and 21602225)the Suzhou Key Laboratory of Surface and Interface Intelligent Matter(grant no.SZS2022011)+2 种基金the Collaborative Innovation Center of Suzhou Nano Science and Technologythe Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the 111 project.
文摘Imide-based conjugated molecules have emerged as a highly promising class of building blocks for constructing n-type semiconducting materials with lowlying lowest unoccupied molecular orbitals and exceptional stability.Although imides,such as naphthalene diimides,perylene diimides and their lateral fused analogs,have been synthesized extensively,the design and synthesis of largerπ-extended molecules incorporating more than two imide groups are desirable but still very challenging.Herein,we report the synthesis of an unprecedented electron-deficient bisanthene tetraimide(ATI)containing a bisantheneconjugated core and four five-membered imide groups,which was successfully achieved via a combined approach of solution and on-surface synthesis.The chemical structures,electronic states,formation mechanism and aromaticity of ATI were systematically investigated by scanning tunneling microscopy,noncontact atomic force microscopy,scanning tunneling spectroscopy,and density functional theory calculations.
基金supported by the National Natural Science Foundation of China(No.52173010)Jining University(Nos.2022HHKJ11,2019BSZX01).
文摘In organic solar cells(OSCs),it is an effective way to improve the power conversion efficiency(PCE)by adding a guest component with appropriate absorption and energy levels in the host system.Herein,a new nonfullerene acceptor(NFA)named TBF-2Cl was developed by the strategy of expanding theπconjugated core of 2,2’-(((4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b’]dithiophene-2,7-diyl)bis(methaneylylidene))bis(5,6-dichloro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile(IDT-4Cl)with two benzene rings.With increase of benzene units,TBF-2Cl exhibits higher lowest unoccupied molecular orbital(LUMO)level of-3.75 eV than that of one benzene unit based NFA IDT-4Cl and fluorene core based NFA F-2Cl,which facilitates enhancing the open-circuit voltage(V_(oc))of ternary devices.Moreover,TBF-2Cl film shows a medium optical bandgap with the absorption range from 500-800 nm,being well complementary with the wide bandgap polymer donor D18 and narrow bandgap NFA CH-6F.Accordingly,a remarkable PCE of 18.92%with a high short-circuit current density(J_(sc))of 27.40 mA·cm^(-2),a fill factor(FF)of 0.749,especially an outstanding V_(oc) of 0.922 V was achieved for the optimal ternary device based on D18:TBF-2Cl:CH-6F,surpassing the binary counterpart(17.08%).The findings provide insight into the development of new guest acceptors for obtaining more efficient OSCs.
基金The financial support from the National Basic Research Program of China(2014CB932300)Natural Science Foundation of Jiangsu Province of China(BK20170630)+1 种基金NSF of China(21633003 and 51602144)sponsored by the JST-CREST ‘‘Phase Interface Science for Highly Efficient Energy Utilization",JST(Japan)
文摘Sodium-ion batteries are promising for large-scale energy storage due to sodium's low cost and infinite abundance. The most popular cathodes for sodium-ion batteries, i.e., the layered sodium-containing oxides, usually exhibit reversible host rearrangement between P-type and O-type stacking upon charge/discharge. Herein we demonstrate that such host rearrangement is unfavorable and can be suppressed by introducing transition-metal ions into sodium layers. The electrode with stabilized P3-type stacking delivers superior rate capability, high energy efficiency, and excellent cycling performance. Owing to the cation-mixing nature, it performs the lowest lattice strain among all reported cathodes for sodium-ion batteries. Our findings highlight the significance of a stable host for sodium-ion storage and moreover underline the fundamental distinction in material design strategy between lithium-and sodium-ion batteries.
基金Project (No. 60573146) supported by the National Natural ScienceFoundation of China
文摘The nesting problem involves arranging pieces on a plate to maximize use of material. A new scheme for 2D ir- regular-shaped nesting problem is proposed. The new scheme is based on the NFP (No Fit Polygon) algorithm and a new placement principle for pieces. The novel placement principle is to place a piece to the position with lowest gravity center based on NFP. In addition, genetic algorithm (GA) is adopted to find an efficient nesting sequence. The proposed scheme can deal with pieces with arbitrary rotation and containing region with holes, and achieves competitive results in experiment on benchmark datasets.
基金supported by the National Public Benefit (Meteorology) Research Foundation of China (Grant No. GYHY201106004)the National Natural Science Foundation of China (Grant Nos. 41005029, 41105065 and 41230421)
文摘Variable thicknesses in the lowest half-ηmodel level （LML） are often used in atmospheric models to compute surface diagnostic fields such as surface latent and sensible heat fluxes.The effects of the LML on simulated tropical cyclone （TC）evolution were investigated in this study using the Weather Research and Forecasting （WRF） model.The results demonstrated notable influences of the LML on TC evolution when the LML was placed below 12 m.The TC intensification rate decreased progressively with a lowering of the LML,but its ultimate intensity change was relatively small.The maximum 10-m winds showed different behavior to minimum sea level pressure and azimuthally-averaged tangential winds,and thus the windpressure relationship was changed accordingly by varying the LML.The TC circulation was more contracted in association with a higher LML.Surface latent heat fluxes were enhanced greatly by elevating the LML,wherein the wind speed at the LML played a dominant role.The changes in the wind speed at the LML were dependent not only on their profile differences,but also the different heights they were taken from.Due to the enhanced surface heat fluxes,more intense latent heat release occurred in the eyewall,which boosted the storm＇s intensification.A higher LML tended to produce a stronger storm,and therefore the surface friction was reinforced,which in turn induced stronger boundary layer inflow together with increased diabatic heating.
文摘A friction stir welding window was developed for effective joining of AA2219 aluminium alloy. Joints were fabricated using different combination of process parameters such as rotational speed and welding speed. Based on macrostructural analysis, the friction stir welding window was constructed. The strength values of joints at different regions of friction stir welding window were analyzed using tensile properties, microstructural studies, and the fracture location of joints was correlated with the lowest hardness distribution profiles. These windows will act as reference maps for selecting appropriate friction stir welding process parameters to get good quality welds of AA2219 aluminium alloys.
基金Japan Society for the Promotion of Science,KAKENHI(18J2013908)。
文摘Understanding what environmental factors are genetically linked to a phenologic al event is critical for predicting responses to climate change.Photo synthetic phenology often varies among a species of evergreen conifers due to local adaptation.However,few empirical studies have revealed relevant relationships between climatic factors in provenance environments and photosynthetic phenology.This study evaluated the effects of environmental conditions of the growing site and seed source provenance on the seasonal changes in maximal photochemical quantum yield of photo systemⅡ(Fv/Fm)in a common garden experiment with 2-year-old seedlings of Sakhalin fir(Abies sachalinensis),a representative species with local adaptation,from four seed source provenances.A logistic model was constructed to explain the seasonal variation of Fv/Fmfrom July to October and the relationships between the estimated model parameters and representative factors featuring provenance environments were evaluated.The landscape gradient of the detected model parameters responsible for the provenance environments was visualized in a map of the distribution area.The lowest temperature was the most plausible factor in the growing environment to explain the seasonal changes of Fv/Fm.Among the representative meteorological factors of provenance environments,the lowest temperatures in July showed significant relationships with two model parameters,explaining the lower limit of Fv/Fmand the higher sensitivity of autumn Fv/Fmdecline.The estimated spatial maps of model parameters consistently showed that the higher the lowest temperature in July in the provenance environment,the lower the Fv/Fmin October and the greater the decrease in the autumn Fv/Fmdecline.Therefore,the lowest summer temperature could be associated with the local adaptation of autumn photosynthetic phenology in A.sachalinensis.
基金financially supported by the Science and Technology Commission of Shanghai Municipality (No. 22ZR1471300)the National Science Foundation of China (Nos. 21871008,51922103 and 21801247)+1 种基金the Key Research Program of Chinese Academy of Sciences (No.QYZDJ-SSW-JSC013)China Postdoctoral Science Foundation (Nos.2020M671242 and 2021T140688)。
文摘Organic cathodes for alkali-metal-ion batteries attract great attentions in recent years,but the ion storage sites are limited to some finite functional groups.This is because an organic cathode must have proper lowest unoccupied molecular orbitals(LUMO) to accept electrons at high potential.Herein,a novel type of organophosphate-based cathode has successfully been explored by tuning the LUMO energy level of organophosphates through metal ions with an inert electron pair.For the first time,the P=O of phytate(PA),N,N,N’,N’-ethylenediaminetetrakis(methylene phytate)(EDTMP),and diethylenetriaminepentakis(methyl phytate)(DTPMP) is activated by lead/bismuth(with 6s2electron pair) to storage Li/Na/K ions reversibly.Typically,density functional theory calculations indicate that the LUMO energy of Bi-PA is greatly reduced from-0.99(PA) to-4.61 eV,which shows the first discharge capacity of 173,182 and 206mAh·g-1and the reversibly capacity of 102,102 and 101mAh·g-1with the discharge platform of 2.4,2.1 and 2.4 V for Li/Na/K-ion battery cathodes,respectively.Similarly,with proper LUMO energy level,Pb-PA(-4.63 eV),Pb-EDTMP(-3.71 eV),and Pb-DTPMP(-4.45 eV) all exhibit admirable performance.This unique strategy of organic materials to alkali-metal-ion battery cathodes offers a new avenue for future energy storage systems.
基金Project supported by National Natural Science Foundation of China(21701039)Natural Science Foundation of Hebei Province(B2017201055)+1 种基金the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(201002099)the Fund for Shanxi"1331 Project"Key Innovative Research Team。
文摘One novel two-dimensional(2D)terbium-based framework[Tb(L2-)(Ac)(DMA)]n(1)(H2 L=4’-(3,5-dicarboxyphenyl)-4,2’:6’,4"-terpyridine)was successfully isolated and structurally characterized.The structural analysis reveals that two Tb3+ions in 1 are bridged by twoη1:η1:μ2 carboxylates from L2-to form a binuclear unit,which is further linked by L2-to generate a 2D layer with kgd topology.Moreover,1 displays excellent thermostability and extensive solvent stability.Luminescent measurements reveal that 1 can be used as a recyclable luminescent probe for detecting pyridine with the lowest detection lim it of 0.12 vol%,and the luminescent mechanism is also discussed.
基金The National Natural Science Foundation of China under contract No.42104035the Basic Scientific Fund for National Public Research Institutes of China under contract No.2023Q05the Natural Science Foundation of Shandong Province under contract No.ZR2020QD087.
文摘Global uniform chart datum(CD)surface construction is the basic upon which to realize various vertical datums transformation,and is of great importance for geospatial data expression under the same vertical datum.Generally,the CD level is computed by developing the function between tidal constituents’harmonic constants and time,i.e.,the lowest astronomical tide is taken as the lowest predicted tide level by adopting the major constituents over a 19-a period.The CD surface prescribed in China is the theoretical lowest tide(TLT)and is calculated using 13 tidal constituents,i.e.,short-period(Q_(1),O_(1),P_(1),K_(1),N_(2),M_(2),S_(2),K_(2),M_(4),MS_(4)and M_(6))and long-period(Sa and Ssa)tidal constituents.Although the accuracy in determining short-period tidal constituents has improved gradually,the long-period tide has not been studied thoroughly owing to nonstationary and temporal variations.Previous studies have intended to evaluate the effect of Sa and Ssa tides in the determination of the TLT level for the purpose of determining a more accurate CD surface for the China seas and adjacent waters.Here,the parameters of long-period tidal correction and long-period tidal correction rate were treated as the effect of both Sa and Ssa on the TLT,and the TOPEX/Poseidon and Jason series satellite altimetry data ranged from October 1992 to April 2022 were adopted to analyze the contribution of long-period tidal constituents.Results showed that the average long-period correction value is 10.10 cm(range from 8.57 cm to 14.98 cm),and that the average long-period tidal contribution rate is 14.56%(range from 9.09%to 23.97%)in the China seas and adjacent waters.Finally,data from 82 tide gauge station with at least a 1-a record of hourly observations were compared with satellite-derived result.We concluded that the long-period tidal contribution should not be neglected in TLT construction.Furthermore,to reduce tidal datum uncertainty,accurate extraction of long-period tidal constituents should receive closer attentions.
基金supported by National Natural Science Foundation of China (grants No. 41572035, 41472309, 41603041 and 41741026)the Open Funds of State Key Laboratory of Loess and Quaternary Geology (grant No. SKLLQG1620)
文摘Objective One of major challenges in paleoenvironmental reconstruction using travertine in the Huanglong area is whether one can accurately determinate the age of travertine through high-precision and high-resolution dating techniques. Previous works of 14C or ESR chronology, however, have shown that the variation of deposition ages of travertine was displayed inconsistent with each other even conflict. For instance, （1） The oldest travertine age （80 ka） located in the middle of this travertine succession is departure from sequential deposition; （2） Top or boundary ages in this sedimentary section, even with the same dating method （14C）, are three times errors, moreover, the age of the depositional sequence is not continuous. We report here the U230Th ages in lowest boundary of travertine in Dawanzhangjia Valley, Huanglong, China, to discuss the effectiveness of U-series dating for cold-water travertine and the significance of age for vicissitude of paleoenvironment.
文摘The procurement of public construction projects must walk a fine line between the corruption of state officials and collusion of contractors. The method of awarding projects to the lowest responsible tenderer was originally implemented to guard against corruption of state officials. However, an investigation of the construction industry in the Canadian province of Quebec showed that lowest-tender-offer procurement gave rise to collusion of companies tendering for the contracts. Alternatively, bestvalue procurement has been used for decades, but here problems arise owing to the necessity of subjective judging of measures other than price to compare bids, giving rise to time-and money-consuming protests. The paper proposes a compelling argument that the construction engineering management(CEM) culture should refocus its efforts on enhancing project cost certainty rather than merely searching for means to design a project in a manner that produces the lowest initial cost, and awards the construction to the lowest tender offer that focuses on cost savings during the project development and delivery process. The difference in the two approaches is subtle but extremely important. To make the transition, the engineering management tools must be advanced to the next level.This means that all project control tools for managing cost,schedule, and technical scope must be transformed from working in the deterministic mode to the stochastic mode,thus making the probability of completing the projectwithin or below its official budget the primary decision criterion. To do so, CEMs must accept that there is a benefit in paying more for an alternative that increases cost certainty for the entire project. The authors of this paper hope that it will provide the grist for a more general dialog across all industry sectors where engineering management is practiced.
文摘The convergences ununiformly and uniformly are established for the nonconforming finite element methods for the second order elliptic problem with the lowest regularity, i.e., in the case that the solution u is an element of H-0(1)(Omega) only.
基金Project supported by the National Natural Science Foundation of China(Nos.10901131,10971166, and 10961024)the National High Technology Research and Development Program of China (No.2009AA01A135)the Natural Science Foundation of Xinjiang Uygur Autonomous Region (No.2010211B04)
文摘A two-level stabilized finite element method for the Stokes eigenvalue problem based on the local Gauss integration is considered. This method involves solving a Stokes eigenvalue problem on a coarse mesh with mesh size H and a Stokes problem on a fine mesh with mesh size h -- O（H2）, which can still maintain the asymptotically optimal accuracy. It provides an approximate solution with the convergence rate of the same order as the usual stabilized finite element solution, which involves solving a Stokes eigenvalue problem on a fine mesh with mesh size h. Hence, the two-level stabilized finite element method can save a large amount of computational time. Moreover, numerical tests confirm the theoretical results of the present method.
基金National Natural Science Foundation of China(90403021)PhD Program Funds of the Education Ministry of China,Pujiang Talent Project of the Shanghai Science Technology Committee(06PJ14114)Hundred Talents Project of Shanghai Institute of Applied Physics
文摘In the strong uniform magnetic field, the noncommutative plane （NCP） caused by the lowest Landau level （LLL） effect, and QED with NCP （QED-NCP） are studied. Being similar to the condensed matter theory of quantum Hall effect, an effective filling factor f（B） is introduced to characterize the possibility that the electrons stay on the LLL. The analytic and numerical results of the differential cross section for the process of backward Compton scattering in accelerator with unpolarized or polarized initial photons are calculated. The existing data of BL38B2 in Spring-8 have been analyzed roughly and compared with the numerical predictions primitively. We propose a precise measurement of the differential cross sections of backward Compton scattering in a strong perpendicular magnetic field, which may reveal the effects of NCP.
基金supported in part by the Ministry of Science and Technology of Taiwan under Grant No.MOST 102-2221-E-011-080-MY3supported by Ministry of Science and Technology of Taiwan under Grant No.MOST 103-2218-E-011-010-MY3
文摘This paper studies the reliability evaluation of a stochastic manufacturing system with multiple production lines in parallel. Multiple repairs and different failure rates, never simultaneously addressed in earlier works, are taken into account. First, a revised graphical methodology integrating transformation and decomposition is utilized to construct the stochastic manufacturing system as a multi-state manufacturing network （MSMN）. In particular, a ＂predecessor-set＂ technique is proposed to deal with multiple repairs. An algorithm is proposed to generate the lowest capacity vectors （LCVs） that stations should provide to satisfy the workloads. Subsequently, the system reliability of the MSMN, which is defined as the probability of demand satisfaction, is calculated in terms of the LCVs. A real case of a printed circuit board manufacturing system is utilized to demonstrate how the system reliability can be evaluated. A further decision making issue is addressed based on the derived system reliability.
文摘Orifice plate energy dissipater as well as plug energy dissipater, as a kind of effective energy dissipater with characteristics of simple structure, convenient construction and high energy dissipation ratio, has become welcomed more and more by hydraulics researchers. The two kinds of energy dissipaters with sudden reduction and sudden enlargement forms are similar in energy dissipation mechanism, but there are differences in energy dissipation characteristics and cavitation characteristics. In the present paper, the differences between orifice plate and plug in energy loss coefficient, relating to their energy dissipation ratio, in the backflow region length, relating to their energy loss coefficient, and in the lowest wall pressure coefficient, relating to their cavitations risk, were analyzed by numerical simulations and physical experiment, and their features in above three aspects were also revealed. The results of research in the present paper demonstrate that the backflow region length of orifice plate is longer than that of plug at the same contraction ratio, the lowest wall pressure coefficient of plug is smaller than that of orifice plate at the same contraction ratio, and the energy loss coefficient of orifice plate is bigger than that of plug, which illustrates that plug is superior to orifice plate in resistance cavitation damage at the same contraction ratio.
