Metal organic framework(MOF) assembled with coordination bonds has the disadvantage of poor stability that limits its application in the field of stationary phase,while covalent organic framework(COF)assembled through...Metal organic framework(MOF) assembled with coordination bonds has the disadvantage of poor stability that limits its application in the field of stationary phase,while covalent organic framework(COF)assembled through covalent bonds exhibits excellent structural stability.It has been shown that the stationary phases prepared by combining MOF and COF can make up for the poor stability of MOF@SiO_(2),and the MOF/COF composites have superior chromatographic separation performance.However,the traditional methods for preparing COF/MOF based stationary phases are generally solvent thermal synthesis.In this study,a green and low-cost synthesis method was proposed for the preparation of MOF/COF@SiO_(2) stationary phase.Firstly,COF@SiO_(2) was prepared in a choline chloride/ethylene glycol based deep eutectic solvent(DES).Secondly,another acid-base tunable DES prepared by mixing p-toluenesulfonic acid(PTSA)and 2-methylimidazole in different proportions was introduced as the reaction solvent and reactant for rapid synthesis of MOF/COF@SiO_(2).Compared with the toxic transition metal-based MOFs selected in most previous studies,a lightweight and non-toxic S-zone metal(calcium) based MOF was employed in this study.PTSA and calcium will form the calcium/oxygen-containing organic acid framework in acidic DES,which assembles with terephthalic acid dissolved in basic DES to form MOF.The strong hydrogen bonding effect of DES can facilitate rapid assembly of Ca-MOF.The obtained Ca-MOF/COF@SiO_(2) can be used for multi-mode chromatography to efficiently separate multiple isomeric/hydrophilic/hydrophobic analytes.The synthesis method of Ca-MOF/COF@SiO_(2) is green and mild,especially the use of acid-base tunable DES promotes the rapid synthesis of non-toxic Ca-MOF/COF@silica composites,which offers an innovative approach of greenly synthesizing novel MOF/COF stationary phases and extends their applications in the field of chromatography.展开更多
For a multi-frequency non-reciprocal optical device,we first realize multi-frequency optical non-reciprocal transmission using a non-Hermitian multi-mode resonator array.Practically,multi-frequency operation can add c...For a multi-frequency non-reciprocal optical device,we first realize multi-frequency optical non-reciprocal transmission using a non-Hermitian multi-mode resonator array.Practically,multi-frequency operation can add channels to the non-reciprocal optical device and the non-reciprocity can route optical signals and prevent the reverse flow of noise.Using the Scully–Lamb model and gain saturation effect,we accomplish dual-frequency non-reciprocal transmission by introducing nonlinearity into a linear array of four-mode resonators.The accomplishment is directly demonstrated by the non-reciprocal transmission phenomena present in the non-divergent peaks.For example,a directional cyclic amplifier is constructed with non-reciprocal units.Regarding potential applications,non-reciprocal optical systems can be employed in dual-frequency control,parallel information processing,photonic integrated circuits,optical devices and so on.展开更多
This thesis tries to explore the problems of the rural English teachers＇ professional development and aims to give some hints on teachers＇ professional development and future teacher training. This thesis makes a su...This thesis tries to explore the problems of the rural English teachers＇ professional development and aims to give some hints on teachers＇ professional development and future teacher training. This thesis makes a survey to 20 rural English teachers from 10 primary schools in the surrounding areas of Linyi City. The survey mainly focuses on the following four aspects： basic situation of the teachers, knowledge of English language and teaching skills, teachers＇ motivation, and self-analysis of their development. With an analysis of the results of the investigation, the author wants to evoke teachers＇ and researchers＇ awareness for improving English language teachers＇ professional development in rural primary schools展开更多
Many authors probe into the models of promoting college students＇ creative thinking abilities from their own perspectives, among which there are innovative works. However, whether we can improve the above abilities o...Many authors probe into the models of promoting college students＇ creative thinking abilities from their own perspectives, among which there are innovative works. However, whether we can improve the above abilities of college students in the oral teaching of university network English still remains blank in the study. Based on the deconstruction of the creative thinking abilities of the students, we should build the components of this capacity from four aspects.展开更多
The strategic design and synthesis of photothermal/photocatalytic materials are pivotal to realizing photothermal conversion water evaporation coupled with photocatalytic sewage purification functions.In this work,bas...The strategic design and synthesis of photothermal/photocatalytic materials are pivotal to realizing photothermal conversion water evaporation coupled with photocatalytic sewage purification functions.In this work,based on the principle of three primary colors,brick-red g-C_(3)N_(4)/Ag_(2)CrO_(4)composite was loaded onto a green polyurethane(PU)sponge using polyvinyl alcohol(PVA)as the linking agent.The resultant PU/PVA/g-C_(3)N_(4)/Ag_(2)CrO_(4)composite exhibits outstanding performance in simultaneous photothermal/photocatalytic water evaporation,pollutant degradation,sterilization,and thermoelectric generation.Under 1.0 kW m^(-2)irradiation,the water evaporation rate reaches 3.19 kg m^(-2)h-1,while a single thermoelectric module generates a maximum thermoelectric output power of 0.25 W m^(-2).Concurrently,rhodamine B(RhB)at a concentration of 4.0×10^(-4)mol L^(-1)undergoes complete photocatalytic degradation within 40 min.When the light intensity is 2.0 kW m^(-2),the evaporation rate soars to 8.52 kg m^(-2)h^(-1),and the thermoelectric power output increases to 1.1 W m^(-2).Furthermore,this photothermal/photocatalytic material based on the principle of three primary colors has excellent photothermal/photocatalytic antibacterial activity against Escherichia coli.By abandoning black light-absorbing materials,more active sites of the photocatalyst can be exposed.The g-C_(3)N_(4)/Ag_(2)CrO_(4)heterojunction accelerates the separation of photogenerated carriers,while the hydrophilic groups in the photothermal/photocatalytic materials reduce the water evaporation enthalpy.This research provides a novel approach for fabricating multi-function photothermal/photocatalytic materials,which could quicken the development of solution to freshwater and electricity energy shortages as well as environmental pollution issues.展开更多
The study focuses on the creep characteristics of significant yellow sandstone for water conservancy, hydropower, and other waterrelated slope excavation unloading rock-graded loading creep characteristics. It conduct...The study focuses on the creep characteristics of significant yellow sandstone for water conservancy, hydropower, and other waterrelated slope excavation unloading rock-graded loading creep characteristics. It conducts a uniaxial graded loading creep test on yellow sandstone under different pre-peak unloading and wetting-drying cycles. The improved nonlinear Nishihara model was obtained by introducing a nonlinear viscous element with an accelerated creep threshold switch. The sensitivity characteristics of the parameters of the improved creep model were analyzed and a nonlinear creep constitutive model was established, considering the unloading-cyclic intrinsic damage induced by water intrusion. The research results show that:(1)With an increase in the unloading point, the porosity of the rock samples initially decreases and then increases. As the number of cyclic water intrusions rises, the porosity of the rock samples gradually increases, reaching a maximum of 9.58% at an unloading point of 70% uniaxial compression stress(0.7 Rc) after five cycles.(2) Total creep deformation increases with the number of cyclic water intrusions;however, with an increase in the unloading ratio, the original samples show an initial decrease, followed by an increase in creep deformation. With a higher unloading ratio and various instances of cyclic water intrusion, the total creep time of the rock samples,compared to the original samples, is reduced by 21.8%and 23.02%. The creep damage mode gradually changes from shear damage to tensile damage.(3) The sensitivity characteristics of the improved creep model parameters show that transient elasticity modulus E1 is affected by the coupling of unloading and cyclic water intrusion. The viscoelastic modulus E2 and viscous coefficient η1 are mainly affected by unloading and cyclic water intrusion.(4) Based on the strain equivalence principle of damage mechanics, the damage treatment of the parameters in the original model is improved to construct a nonlinear creep constitutive model that considers unloading-cyclic water intrusion damage. A parameter inversion and comparison to the traditional Nishihara model reveal an average relative standard deviation of 0.271%,significantly less than 1%, indicating a more accurate nonlinear creep constitutive model. The research results are crucial for analyzing the long-term stability of water-related steep rocky slopes post-excavation and unloading and for preventing and controlling creep-type landslide disasters.展开更多
The content of soluble sugars is a vital parameter that indicates the quality of fleshy fruits such as apple(Malus domestica Borkh.).Studying the patterns of accumulation of soluble sugars and regulatory mechanisms as...The content of soluble sugars is a vital parameter that indicates the quality of fleshy fruits such as apple(Malus domestica Borkh.).Studying the patterns of accumulation of soluble sugars and regulatory mechanisms associated with fruit development is crucial for breeding improved fruit varieties.Here,we report that MdCIbHLH1,a low temperature-induced b HLH transcription factor,inhibits the accumulation of soluble sugars by regulating sugar-metabolizing enzyme activities,photosynthetic performance,and the expression of sugar-related genes in developing apple fruits.MdCIbHLH1 inhibits MdFBP and MdPEPCK expression,thus blocking the conversion of acids to sugars in apple fruits.We also discovered that MdCIbHLH1 decreases the photosynthetic rate and carbohydrate accumulation in apple leaves.Our results suggest that soluble sugar accumulation in apple fruits is influenced by multiple factors,including metabolic status,photosynthesis,and carbohydrate allocation.MdCIbHLH1 is critically involved in controlling the accumulation of soluble sugars by coordinating carbohydrate synthesis and allocation,thus influencing sugar transport and its metabolism during the development of apple fruits.展开更多
The C—F bond transformation of gem-difluorinated cyclopropanes without cleavage of the highly strained C—C bond is an intractable challenge. The synthesis of cyclopropanone ketals via double defluorination of gem-di...The C—F bond transformation of gem-difluorinated cyclopropanes without cleavage of the highly strained C—C bond is an intractable challenge. The synthesis of cyclopropanone ketals via double defluorination of gem-difluorinated cyclo-propanesunder transition-metal free and basic conditions has been developed. A broad range of gem-difluorinated cyclopro-panesand alcohols are amenable in present reaction to permit the synthesis of corresponding products in high yields. The reaction is elucidated to proceed via elimination and addition other than direct substitution based on the mechanistic studies. This transformation not only provides a new strategy for the construction of cyclopropanone ketals, but also reveals a new paradigm on C—F bond transformation without ring-opening of gem-difluorinated cyclopropanes.展开更多
The origin of birds from theropod dinosaurs,by any measures,is the most eye-catching evolutionary transition in the history of life,which encompasses numerous extensive morphological and biological changes.Compared to...The origin of birds from theropod dinosaurs,by any measures,is the most eye-catching evolutionary transition in the history of life,which encompasses numerous extensive morphological and biological changes.Compared to postcranium,little progress has been made regarding the evolutionary assemblage of the birds’skull,because of few detailed early records of cranial materials of stem lineages.Anchiornis is the oldest known record of the Paraves(~160 Ma),the most inclusive clade that contains all living birds but not Caudipteryx or Epidexipteryx.With hundreds of known specimens,Anchiornis constitutes an ideal taxon for investigating morphological modifications across the theropod-bird transition,but its cranial morphology remains enigmatic.Here we present in-depth description of the cranial morphology of Anchiornis based on three-dimensional reconstruction of a well-preserved specimen,including elements from the temporal and palatal regions that are poorly recognized previously.Our study shows that Anchiornis retains the plesiomorphic dinosaurian condition in having a diapsid akinetic skull.The mixture of cranial characters,shared with dromaeosaurids,troodontids,and stemward avialans,present in Anchiornis demonstrates the complex history of early avialan cranial evolution.展开更多
To promote the growth of cutting seeding of poplar(Populus L.),nitrogen(N)fertilizer and surface weed managements were required.We here conducted a pot experiment to examine the effects of natural vegetation,barnyardg...To promote the growth of cutting seeding of poplar(Populus L.),nitrogen(N)fertilizer and surface weed managements were required.We here conducted a pot experiment to examine the effects of natural vegetation,barnyardgrass(Echinochloa Beauv.),and sesbania(Sesbania cannabina pers.)on the growth of poplar cutting seedlings,soil properties,and ammonia(NH3)volatilization under three N inputs(0,0.5,and 1.5 g/pot,i.e.,N0,N0.5,and N1,respectively).Results showed that N application promoted the growth of poplar cutting seedlings,including plant height,ground diameter,and biomass,compared with N0 treatment.Moreover,under N0,sesbania significantly increased the plant height by 87.1%,barnyardgrass and sesbania significantly increased the ground diameter(16.2%and 51.5%),and biomass(67.4%and 74.7%)of poplar cutting seedlings,compared with natural vegetation management.Compared to natural vegetation,soil organic matter(SOM)of barnyardgrass and sesbania covered soil significantly increased by 12.4%and 18.7%at N1,respectively.In addition,soil total N(TN)content was significantly increased by 15.8%in barnyardgrass planted at N0.The soil ammonium N(NH_(4)^(+)-N)content decreased with the planting of barnyardgrass and sesbania across all levels of N application.At N0.5,the nitrate N(NO_(3)^(−)-N)content of soil planted with barnyardgrass significantly increased compared to both the natural vegetation and the sesbania groups.Compared to the natural vegetation,the soil available phosphorus(AP)content of the barnyardgrass group significantly increasing by 78.8%at N0.5,soil available potassium(AK)content was significantly reduced by 12.5%in the sesbania group at N0 and increased by 24.1%in the barnyardgrass group at N1.We found that cumulative NH3 emissions were significantly higher in all treatment groups at the N1 level than that at the N0.5 level,while the differences among the three plants treated were not significant.The results suggest that both barnyardgrass and sesbania promote seedling growth in the short term,while also increase certain properties.Therefore,effective herb management during the seedling stage is recommended in nurseries to support seedling growth and retain soil fertility.展开更多
Considering the three-dimensional(3D) U-Net lacks sufficient local feature extraction for image features and lacks attention to the fusion of high-and low-level features, we propose a new model called 3DMAU-Net based ...Considering the three-dimensional(3D) U-Net lacks sufficient local feature extraction for image features and lacks attention to the fusion of high-and low-level features, we propose a new model called 3DMAU-Net based on the 3D U-Net architecture for liver region segmentation. Our model replaces the last two layers of the 3D U-Net with a sliding window-based multilayer perceptron(SMLP), enabling better extraction of local image features. We also design a high-and low-level feature fusion dilated convolution block that focuses on local features and better supplements the surrounding information of the target region. This block is embedded in the entire encoding process, ensuring that the overall network is not simply downsampling. Before each feature extraction, the input features are processed by the dilated convolution block. We validate our experiments on the liver tumor segmentation challenge 2017(Lits2017) dataset, and our model achieves a Dice coefficient of 0.95, which is an improvement of 0.015 compared to the 3D U-Net model. Furthermore, we compare our results with other segmentation methods, and our model consistently outperforms them.展开更多
Research on Antarctic microbial diversity has primarily focused on 3 areas:freshwater lake sediments,penguin colonies,and seawater in ice-free regions.There is a scarcity of research on the impact of slopes on microbi...Research on Antarctic microbial diversity has primarily focused on 3 areas:freshwater lake sediments,penguin colonies,and seawater in ice-free regions.There is a scarcity of research on the impact of slopes on microbial community structure,and this study effectively fills this gap.This study focused on the soil in the sparse vegetated tundra on a hillside near the southern coastline of the Antarctic Great Wall Station.The influence of slope position,soil physicochemical properties,and vegetated area on soil bacterial community structure was analyzed.High-throughput sequencing technology was employed to characterize a 16S rRNA gene fragment in soil samples from 5 slope areas and estimate bacterial abundance.Calculation ofα-diversity andβ-diversity indices,and community structure analysis were used to compare the species richness among sampling points,analyze similarities in soil bacterial community structure and composition,and identify the core bacterial population.In the non-vegetated area,the soil on the mountaintop,hillside,and at the foot of the slope showed similar physicochemical properties.In the vegetated area,the soil physicochemical properties were highly similar on the mountaintop,hillside,the foot of the slope,and the foot of the mountain.Weighted Gene Co-expression Network Analysis showed that total organic carbon,pH,and PO_(4)^(3-)-P might affect the structure of bacterial communities at the sampling point by changing the relative abundance of Chthoniobacterales,Sediminibacterium,and Actinobacteria.We hypothesize that slope-driven nutrient transport,amplified by vegetated areas(in the tundra),is a primary driver of bacterial community structure in the Antarctic tundra soil.These results provide insights into the impact of slope on microbial community structure in Antarctica.展开更多
Periplocin,periplocymarin and periplogenin are the main active components of Cortex Periplocae.The most cytotoxic constituent of Cortex Periplocae,periplocin is an alpha cardiac glycoside with a steroid core and an un...Periplocin,periplocymarin and periplogenin are the main active components of Cortex Periplocae.The most cytotoxic constituent of Cortex Periplocae,periplocin is an alpha cardiac glycoside with a steroid core and an unsaturated five-membered lactone ring structure.Periplocymarin is a secondary alpha cardiac glycoside,which is produced by removing one molecule of glucose from periplocin,and periplogenin is the glycosidic portion and the basic unit of periplocin and periplocymarin.These three cardiac glycosides,by virtue of their unique pharmacological activities and mechanisms of action,mediate signaling pathways,mainly the retinoblastoma and p53 signaling pathways,and regulate cell cycle proteins,thereby hindering the proliferation of cancer cells and altering the cell cycle process.These glycosides also regulate caspase proteins by mediating endogenous and exogenous pathways,thereby inducing the apoptosis of cancer cells.This minireview focuses on the inhibitory effects of periplocin,periplocymarin and periplogenin on cancer,and explores their potential antitumor mechanisms.展开更多
In industrial applications,plate-like structures such as steel strips in continuous hot-dip galvanizing and papers under fan action are ubiquitous.The vibration issues that arise when these structures are in axial mot...In industrial applications,plate-like structures such as steel strips in continuous hot-dip galvanizing and papers under fan action are ubiquitous.The vibration issues that arise when these structures are in axial motion,and are influenced by fluids and thermal fields,have attracted significant attention from the academic community.This study focuses on the nonlinear dynamic behavior of axially transporting immersed viscoelastic plates with particular emphasis on internal resonance and speed-dependent tension.The governing equation and the related boundary conditions for the axially transporting viscoelastic immersed plate are derived with Hamilton's principle,prioritizing the impact of time-varying tension induced by speed perturbations.Based on the second-order Galerkin truncation,the governing equation is discretized into a system of second-order ordinary differential equations.The multi-scale method is used to analyze the stable steady-state response of the immersed viscoelastic plate.The conditions for achieving a 3:1 frequency ratio between the first two orders of the system are analytically deduced.Notably,when the viscoelastic coefficient diminishes,the stability boundaries exhibit increased complexity,manifesting as the irregular W-shaped contours in the parameter space.Numerical examples comprehensively investigate the effects of viscoelasticity on both the stability region and the steady-state response under internal resonance conditions.Finally,the accuracy of the obtained results is validated through numerical computation.展开更多
The Yishui complex,located in the western Shandong area of the North China Craton,is representative of the Archean crystalline basement of the North China Craton to explore the early tectonic-thermal evolution history...The Yishui complex,located in the western Shandong area of the North China Craton,is representative of the Archean crystalline basement of the North China Craton to explore the early tectonic-thermal evolution history of the Earth.Detailed petrography,mineral chemistry,metamorphic evolution and zircon U-Pb dating are presented for felsic granulite and two-pyroxene granulite from the Yishui complex to contribute to new insights into the Neoarchean tectonic evolution of the North China Craton.Three mineral assemblages are recognized for these granulite samples,including the prograde(M1),peak(M2)and retrograde(M3)mineral assemblages.Conventional geothermobarometry and phase equilibrium modeling yield P-T conditions of 6.5-10.9 kbar/718-839℃ for the peak metamorphism,which define a medium-pressure granulite-facies metamorphism occurred at middle to lower crust.Anticlockwise P-T paths with near-isobaric cooling(IBC)retrograde segments were reconstructed.Zircon LA-ICP-MS U-Pb dating suggests that the protolith of the felsic granulite was emplaced at 2541±7 Ma and the subsequent medium-pressure granulite-facies metamorphism occurred at 2518-2494 Ma.A two-stage mantle plume related crustal-scale sagduction geodynamic regime is proposed in the western Shandong terrane in the Neoarchean.展开更多
Based on the Kraus operator-sum representation of the analytical solution of the diffusion equation,we obtain the evolution of a general linear state in the diffusion channel.Also,we study the quantum statistical prop...Based on the Kraus operator-sum representation of the analytical solution of the diffusion equation,we obtain the evolution of a general linear state in the diffusion channel.Also,we study the quantum statistical properties of the initial general linear state and its von-Neumann entropy evolution in the diffusion channel,especially find that the entropy evolution is influenced by the diffusion noise and the thermal parameter but without the displacement.展开更多
Strontium has similar chemical properties to calcium and has recently been recognized as a non-essential beneficial element for plants.In order to compare the effects of strontium and calcium on improving salt toleran...Strontium has similar chemical properties to calcium and has recently been recognized as a non-essential beneficial element for plants.In order to compare the effects of strontium and calcium on improving salt tolerance of Chinese cabbage during the germination stage,2,4,and 8 mmol/L of SrCl_(2),CaCl_(2) or an equimolar mixture of both were added separately to a 150 mmol/L NaCl solution.The results showed that Ca-Sr addition significantly increased seed viability,seed vigor,seed germination rate and seed germination uniformity of Chinese cabbage compared with the salt-control group.The differences in germination percentage(GP)and germination energy(GE)among the Ca-addition and Sr-addition groups were not significant,and the differences in coefficient of rate of germination(CRG),index of rate of germination(IRG)and coefficient of variation of the germination time(CVT)were relatively small,but clear differences were observed in germination index(GI),vigor index(VI)and coefficient of uniformity of germination(CUG).The results of GI and VI indicated that the higher the concentration of Ca-addition or Sr-addition,the more significant the enhancement of seed vigor.Under saline stress(150 mmol/L NaCl),the Ca-Sr co-addition outperformed Sr-treatment alone,and Ca-addition achieved the highest seed vigor at equivalent concentrations.Furthermore,all Ca-Sr treatments significantly enhanced the uniformity of Chinese cabbage sprouts exposed to 150 mM NaCl,with the best uniformity improved by the addition of 2 and 4 mmol/L SrCl_(2).Ca-Sr treatments increased the salt tolerance of Chinese cabbage sprouts during the germination stage mainly because the Ca2+and Sr2+significantly enhanced plasma membrane stability and reduced oxidative stress(as indicated by decreased contents of malondialdehyde and O2⋅-contents)in sprouts.The decrease of soluble sugar and proline content caused by Ca-Sr addition implies that elevated levels of these osmolytes were not the primary contributors to improved seed germinability in Chinese cabbage.These findings demonstrate that Sr is a beneficial element for enhancing salt tolerance in plants,laying a theoretical foundation for the development and application of strontium in agriculture.展开更多
Metal-organic frameworks(MOFs)with superior physicochemical properties have great potential for applications in chromatographic separation.However,currently popular methods for the synthesis of MOFbased silica composi...Metal-organic frameworks(MOFs)with superior physicochemical properties have great potential for applications in chromatographic separation.However,currently popular methods for the synthesis of MOFbased silica composite materials usually require the use of harmful organic solvents and long-term hightemperature sealing reactions.In order to respond to the needs of green chromatography,it is urgent to develop a new green organic-solvent-free strategy for the synthesis of MOF@SiO_(2)composites.MIP-202 is a zirconium-MOF constructed from zirconium ion and l-aspartic acid,which features green synthesis as well as good hydrolytic stability and chemical stability.In this paper,SiO_(2)-NH_(2) was first prepared in a hydrophilic deep eutectic solvent,and then an amino acid-based MOF material(MIP-202)was modified on the surface of the SiO_(2)-NH_(2) in an aqueous solution to obtain a MIP-202@SiO_(2) composite material.The multi-mode separation performance of MIP-202@SiO_(2) as a promising liquid chromatographic stationary phase was particularly evaluated and the separation mechanisms were discussed.The MIP-202@SiO_(2) column exhibited excellent separation ability for aromatic positional isomers.In addition,chiral enantiomers and hydrophilic analytes were also satisfactorily detected and separated.This work provides a new approach for the facile synthesis of MOF-based liquid chromatographic separation material by using green deep eutectic solvent and water as the reaction media.展开更多
基金supported by National Natural Science Foundation of China (Nos.21906124,32302202)Natural Science Foundation of Hubei Province (No.2017CFB220)Natural Science Foundation of Shandong Province (No.ZR2023MH278)。
文摘Metal organic framework(MOF) assembled with coordination bonds has the disadvantage of poor stability that limits its application in the field of stationary phase,while covalent organic framework(COF)assembled through covalent bonds exhibits excellent structural stability.It has been shown that the stationary phases prepared by combining MOF and COF can make up for the poor stability of MOF@SiO_(2),and the MOF/COF composites have superior chromatographic separation performance.However,the traditional methods for preparing COF/MOF based stationary phases are generally solvent thermal synthesis.In this study,a green and low-cost synthesis method was proposed for the preparation of MOF/COF@SiO_(2) stationary phase.Firstly,COF@SiO_(2) was prepared in a choline chloride/ethylene glycol based deep eutectic solvent(DES).Secondly,another acid-base tunable DES prepared by mixing p-toluenesulfonic acid(PTSA)and 2-methylimidazole in different proportions was introduced as the reaction solvent and reactant for rapid synthesis of MOF/COF@SiO_(2).Compared with the toxic transition metal-based MOFs selected in most previous studies,a lightweight and non-toxic S-zone metal(calcium) based MOF was employed in this study.PTSA and calcium will form the calcium/oxygen-containing organic acid framework in acidic DES,which assembles with terephthalic acid dissolved in basic DES to form MOF.The strong hydrogen bonding effect of DES can facilitate rapid assembly of Ca-MOF.The obtained Ca-MOF/COF@SiO_(2) can be used for multi-mode chromatography to efficiently separate multiple isomeric/hydrophilic/hydrophobic analytes.The synthesis method of Ca-MOF/COF@SiO_(2) is green and mild,especially the use of acid-base tunable DES promotes the rapid synthesis of non-toxic Ca-MOF/COF@silica composites,which offers an innovative approach of greenly synthesizing novel MOF/COF stationary phases and extends their applications in the field of chromatography.
基金supported by the National Nature Science Foundation of China(Grant Nos.12475019 and 12073056)the Major National Science and Technology Project of China(Grant No.BX2024B054)+1 种基金National Lab of Solid State Microstructure of Nanjing University(Grant Nos.M35040,M35053,and M37014)the Natural Science Foundation of Shandong Province(Grant No.ZR2024MA038)。
文摘For a multi-frequency non-reciprocal optical device,we first realize multi-frequency optical non-reciprocal transmission using a non-Hermitian multi-mode resonator array.Practically,multi-frequency operation can add channels to the non-reciprocal optical device and the non-reciprocity can route optical signals and prevent the reverse flow of noise.Using the Scully–Lamb model and gain saturation effect,we accomplish dual-frequency non-reciprocal transmission by introducing nonlinearity into a linear array of four-mode resonators.The accomplishment is directly demonstrated by the non-reciprocal transmission phenomena present in the non-divergent peaks.For example,a directional cyclic amplifier is constructed with non-reciprocal units.Regarding potential applications,non-reciprocal optical systems can be employed in dual-frequency control,parallel information processing,photonic integrated circuits,optical devices and so on.
文摘This thesis tries to explore the problems of the rural English teachers＇ professional development and aims to give some hints on teachers＇ professional development and future teacher training. This thesis makes a survey to 20 rural English teachers from 10 primary schools in the surrounding areas of Linyi City. The survey mainly focuses on the following four aspects： basic situation of the teachers, knowledge of English language and teaching skills, teachers＇ motivation, and self-analysis of their development. With an analysis of the results of the investigation, the author wants to evoke teachers＇ and researchers＇ awareness for improving English language teachers＇ professional development in rural primary schools
文摘Many authors probe into the models of promoting college students＇ creative thinking abilities from their own perspectives, among which there are innovative works. However, whether we can improve the above abilities of college students in the oral teaching of university network English still remains blank in the study. Based on the deconstruction of the creative thinking abilities of the students, we should build the components of this capacity from four aspects.
基金supported by the National Natural Science Foundation of China(52372234)the Research Foundation for Talented Scholars of Linyi University(Z6122010).
文摘The strategic design and synthesis of photothermal/photocatalytic materials are pivotal to realizing photothermal conversion water evaporation coupled with photocatalytic sewage purification functions.In this work,based on the principle of three primary colors,brick-red g-C_(3)N_(4)/Ag_(2)CrO_(4)composite was loaded onto a green polyurethane(PU)sponge using polyvinyl alcohol(PVA)as the linking agent.The resultant PU/PVA/g-C_(3)N_(4)/Ag_(2)CrO_(4)composite exhibits outstanding performance in simultaneous photothermal/photocatalytic water evaporation,pollutant degradation,sterilization,and thermoelectric generation.Under 1.0 kW m^(-2)irradiation,the water evaporation rate reaches 3.19 kg m^(-2)h-1,while a single thermoelectric module generates a maximum thermoelectric output power of 0.25 W m^(-2).Concurrently,rhodamine B(RhB)at a concentration of 4.0×10^(-4)mol L^(-1)undergoes complete photocatalytic degradation within 40 min.When the light intensity is 2.0 kW m^(-2),the evaporation rate soars to 8.52 kg m^(-2)h^(-1),and the thermoelectric power output increases to 1.1 W m^(-2).Furthermore,this photothermal/photocatalytic material based on the principle of three primary colors has excellent photothermal/photocatalytic antibacterial activity against Escherichia coli.By abandoning black light-absorbing materials,more active sites of the photocatalyst can be exposed.The g-C_(3)N_(4)/Ag_(2)CrO_(4)heterojunction accelerates the separation of photogenerated carriers,while the hydrophilic groups in the photothermal/photocatalytic materials reduce the water evaporation enthalpy.This research provides a novel approach for fabricating multi-function photothermal/photocatalytic materials,which could quicken the development of solution to freshwater and electricity energy shortages as well as environmental pollution issues.
基金We gratefully acknowledge the financial support from the Key Laboratory of Geological Safety of Coastal Urban Underground Space,Ministry of Natural Resources(BHKF2022Y03)Shandong Provincial Colleges and Universities Youth Innovation Technology Support Program,Education Department of Shandong Province(grant number 2023KJ092).
文摘The study focuses on the creep characteristics of significant yellow sandstone for water conservancy, hydropower, and other waterrelated slope excavation unloading rock-graded loading creep characteristics. It conducts a uniaxial graded loading creep test on yellow sandstone under different pre-peak unloading and wetting-drying cycles. The improved nonlinear Nishihara model was obtained by introducing a nonlinear viscous element with an accelerated creep threshold switch. The sensitivity characteristics of the parameters of the improved creep model were analyzed and a nonlinear creep constitutive model was established, considering the unloading-cyclic intrinsic damage induced by water intrusion. The research results show that:(1)With an increase in the unloading point, the porosity of the rock samples initially decreases and then increases. As the number of cyclic water intrusions rises, the porosity of the rock samples gradually increases, reaching a maximum of 9.58% at an unloading point of 70% uniaxial compression stress(0.7 Rc) after five cycles.(2) Total creep deformation increases with the number of cyclic water intrusions;however, with an increase in the unloading ratio, the original samples show an initial decrease, followed by an increase in creep deformation. With a higher unloading ratio and various instances of cyclic water intrusion, the total creep time of the rock samples,compared to the original samples, is reduced by 21.8%and 23.02%. The creep damage mode gradually changes from shear damage to tensile damage.(3) The sensitivity characteristics of the improved creep model parameters show that transient elasticity modulus E1 is affected by the coupling of unloading and cyclic water intrusion. The viscoelastic modulus E2 and viscous coefficient η1 are mainly affected by unloading and cyclic water intrusion.(4) Based on the strain equivalence principle of damage mechanics, the damage treatment of the parameters in the original model is improved to construct a nonlinear creep constitutive model that considers unloading-cyclic water intrusion damage. A parameter inversion and comparison to the traditional Nishihara model reveal an average relative standard deviation of 0.271%,significantly less than 1%, indicating a more accurate nonlinear creep constitutive model. The research results are crucial for analyzing the long-term stability of water-related steep rocky slopes post-excavation and unloading and for preventing and controlling creep-type landslide disasters.
基金supported by grants from the National Natural Science Foundation of China(Grant Nos.32122080,31972375)Shandong Province(Grant No.ZR2020YQ25)。
文摘The content of soluble sugars is a vital parameter that indicates the quality of fleshy fruits such as apple(Malus domestica Borkh.).Studying the patterns of accumulation of soluble sugars and regulatory mechanisms associated with fruit development is crucial for breeding improved fruit varieties.Here,we report that MdCIbHLH1,a low temperature-induced b HLH transcription factor,inhibits the accumulation of soluble sugars by regulating sugar-metabolizing enzyme activities,photosynthetic performance,and the expression of sugar-related genes in developing apple fruits.MdCIbHLH1 inhibits MdFBP and MdPEPCK expression,thus blocking the conversion of acids to sugars in apple fruits.We also discovered that MdCIbHLH1 decreases the photosynthetic rate and carbohydrate accumulation in apple leaves.Our results suggest that soluble sugar accumulation in apple fruits is influenced by multiple factors,including metabolic status,photosynthesis,and carbohydrate allocation.MdCIbHLH1 is critically involved in controlling the accumulation of soluble sugars by coordinating carbohydrate synthesis and allocation,thus influencing sugar transport and its metabolism during the development of apple fruits.
文摘The C—F bond transformation of gem-difluorinated cyclopropanes without cleavage of the highly strained C—C bond is an intractable challenge. The synthesis of cyclopropanone ketals via double defluorination of gem-difluorinated cyclo-propanesunder transition-metal free and basic conditions has been developed. A broad range of gem-difluorinated cyclopro-panesand alcohols are amenable in present reaction to permit the synthesis of corresponding products in high yields. The reaction is elucidated to proceed via elimination and addition other than direct substitution based on the mechanistic studies. This transformation not only provides a new strategy for the construction of cyclopropanone ketals, but also reveals a new paradigm on C—F bond transformation without ring-opening of gem-difluorinated cyclopropanes.
文摘The origin of birds from theropod dinosaurs,by any measures,is the most eye-catching evolutionary transition in the history of life,which encompasses numerous extensive morphological and biological changes.Compared to postcranium,little progress has been made regarding the evolutionary assemblage of the birds’skull,because of few detailed early records of cranial materials of stem lineages.Anchiornis is the oldest known record of the Paraves(~160 Ma),the most inclusive clade that contains all living birds but not Caudipteryx or Epidexipteryx.With hundreds of known specimens,Anchiornis constitutes an ideal taxon for investigating morphological modifications across the theropod-bird transition,but its cranial morphology remains enigmatic.Here we present in-depth description of the cranial morphology of Anchiornis based on three-dimensional reconstruction of a well-preserved specimen,including elements from the temporal and palatal regions that are poorly recognized previously.Our study shows that Anchiornis retains the plesiomorphic dinosaurian condition in having a diapsid akinetic skull.The mixture of cranial characters,shared with dromaeosaurids,troodontids,and stemward avialans,present in Anchiornis demonstrates the complex history of early avialan cranial evolution.
基金funded by the Science and Technology Innovation Programof Jiangsu Province,China for“Carbon Dioxide Emission Peaking and Carbon Neutrality”(BE2022307).
文摘To promote the growth of cutting seeding of poplar(Populus L.),nitrogen(N)fertilizer and surface weed managements were required.We here conducted a pot experiment to examine the effects of natural vegetation,barnyardgrass(Echinochloa Beauv.),and sesbania(Sesbania cannabina pers.)on the growth of poplar cutting seedlings,soil properties,and ammonia(NH3)volatilization under three N inputs(0,0.5,and 1.5 g/pot,i.e.,N0,N0.5,and N1,respectively).Results showed that N application promoted the growth of poplar cutting seedlings,including plant height,ground diameter,and biomass,compared with N0 treatment.Moreover,under N0,sesbania significantly increased the plant height by 87.1%,barnyardgrass and sesbania significantly increased the ground diameter(16.2%and 51.5%),and biomass(67.4%and 74.7%)of poplar cutting seedlings,compared with natural vegetation management.Compared to natural vegetation,soil organic matter(SOM)of barnyardgrass and sesbania covered soil significantly increased by 12.4%and 18.7%at N1,respectively.In addition,soil total N(TN)content was significantly increased by 15.8%in barnyardgrass planted at N0.The soil ammonium N(NH_(4)^(+)-N)content decreased with the planting of barnyardgrass and sesbania across all levels of N application.At N0.5,the nitrate N(NO_(3)^(−)-N)content of soil planted with barnyardgrass significantly increased compared to both the natural vegetation and the sesbania groups.Compared to the natural vegetation,the soil available phosphorus(AP)content of the barnyardgrass group significantly increasing by 78.8%at N0.5,soil available potassium(AK)content was significantly reduced by 12.5%in the sesbania group at N0 and increased by 24.1%in the barnyardgrass group at N1.We found that cumulative NH3 emissions were significantly higher in all treatment groups at the N1 level than that at the N0.5 level,while the differences among the three plants treated were not significant.The results suggest that both barnyardgrass and sesbania promote seedling growth in the short term,while also increase certain properties.Therefore,effective herb management during the seedling stage is recommended in nurseries to support seedling growth and retain soil fertility.
基金supported by the Shandong Provincial Natural Science Foundation (Nos.ZR2023MF062 and ZR2021MF115)the Introduction and Cultivation Program for Young Innovative Talents of Universities in Shandong (No.2021QCYY003)。
文摘Considering the three-dimensional(3D) U-Net lacks sufficient local feature extraction for image features and lacks attention to the fusion of high-and low-level features, we propose a new model called 3DMAU-Net based on the 3D U-Net architecture for liver region segmentation. Our model replaces the last two layers of the 3D U-Net with a sliding window-based multilayer perceptron(SMLP), enabling better extraction of local image features. We also design a high-and low-level feature fusion dilated convolution block that focuses on local features and better supplements the surrounding information of the target region. This block is embedded in the entire encoding process, ensuring that the overall network is not simply downsampling. Before each feature extraction, the input features are processed by the dilated convolution block. We validate our experiments on the liver tumor segmentation challenge 2017(Lits2017) dataset, and our model achieves a Dice coefficient of 0.95, which is an improvement of 0.015 compared to the 3D U-Net model. Furthermore, we compare our results with other segmentation methods, and our model consistently outperforms them.
基金supported by the National Natural Science Foundation of China(Grant no.32501365)Natural Science Foundation of Shandong Province,China(Grant no.ZR2025QC1456).
文摘Research on Antarctic microbial diversity has primarily focused on 3 areas:freshwater lake sediments,penguin colonies,and seawater in ice-free regions.There is a scarcity of research on the impact of slopes on microbial community structure,and this study effectively fills this gap.This study focused on the soil in the sparse vegetated tundra on a hillside near the southern coastline of the Antarctic Great Wall Station.The influence of slope position,soil physicochemical properties,and vegetated area on soil bacterial community structure was analyzed.High-throughput sequencing technology was employed to characterize a 16S rRNA gene fragment in soil samples from 5 slope areas and estimate bacterial abundance.Calculation ofα-diversity andβ-diversity indices,and community structure analysis were used to compare the species richness among sampling points,analyze similarities in soil bacterial community structure and composition,and identify the core bacterial population.In the non-vegetated area,the soil on the mountaintop,hillside,and at the foot of the slope showed similar physicochemical properties.In the vegetated area,the soil physicochemical properties were highly similar on the mountaintop,hillside,the foot of the slope,and the foot of the mountain.Weighted Gene Co-expression Network Analysis showed that total organic carbon,pH,and PO_(4)^(3-)-P might affect the structure of bacterial communities at the sampling point by changing the relative abundance of Chthoniobacterales,Sediminibacterium,and Actinobacteria.We hypothesize that slope-driven nutrient transport,amplified by vegetated areas(in the tundra),is a primary driver of bacterial community structure in the Antarctic tundra soil.These results provide insights into the impact of slope on microbial community structure in Antarctica.
基金Supported by Traditional Chinese Medicine Science and Technology Project of Shandong Province,China,No.M-2023131The Science and Technology Development Fund Project of the Affiliated Hospital of Xuzhou Medical University,China,No.XYFM202348.
文摘Periplocin,periplocymarin and periplogenin are the main active components of Cortex Periplocae.The most cytotoxic constituent of Cortex Periplocae,periplocin is an alpha cardiac glycoside with a steroid core and an unsaturated five-membered lactone ring structure.Periplocymarin is a secondary alpha cardiac glycoside,which is produced by removing one molecule of glucose from periplocin,and periplogenin is the glycosidic portion and the basic unit of periplocin and periplocymarin.These three cardiac glycosides,by virtue of their unique pharmacological activities and mechanisms of action,mediate signaling pathways,mainly the retinoblastoma and p53 signaling pathways,and regulate cell cycle proteins,thereby hindering the proliferation of cancer cells and altering the cell cycle process.These glycosides also regulate caspase proteins by mediating endogenous and exogenous pathways,thereby inducing the apoptosis of cancer cells.This minireview focuses on the inhibitory effects of periplocin,periplocymarin and periplogenin on cancer,and explores their potential antitumor mechanisms.
基金Project supported by the Science and Technology Support Plan for Youth Innovation of Colleges and Universities of Shandong Province of China(No.2023KJ215)the National Natural Science Foundation of China(Nos.12002142 and 52405274)the National Natural Science Foundation of Shanghai of China(No.ZR2023QE100)。
文摘In industrial applications,plate-like structures such as steel strips in continuous hot-dip galvanizing and papers under fan action are ubiquitous.The vibration issues that arise when these structures are in axial motion,and are influenced by fluids and thermal fields,have attracted significant attention from the academic community.This study focuses on the nonlinear dynamic behavior of axially transporting immersed viscoelastic plates with particular emphasis on internal resonance and speed-dependent tension.The governing equation and the related boundary conditions for the axially transporting viscoelastic immersed plate are derived with Hamilton's principle,prioritizing the impact of time-varying tension induced by speed perturbations.Based on the second-order Galerkin truncation,the governing equation is discretized into a system of second-order ordinary differential equations.The multi-scale method is used to analyze the stable steady-state response of the immersed viscoelastic plate.The conditions for achieving a 3:1 frequency ratio between the first two orders of the system are analytically deduced.Notably,when the viscoelastic coefficient diminishes,the stability boundaries exhibit increased complexity,manifesting as the irregular W-shaped contours in the parameter space.Numerical examples comprehensively investigate the effects of viscoelasticity on both the stability region and the steady-state response under internal resonance conditions.Finally,the accuracy of the obtained results is validated through numerical computation.
基金supported by the Natural Science Foundation of Shandong Provence(Grant No.ZR2023MD058)National Natural Science Foundation of China(Grant Nos.42072219,41802201)。
文摘The Yishui complex,located in the western Shandong area of the North China Craton,is representative of the Archean crystalline basement of the North China Craton to explore the early tectonic-thermal evolution history of the Earth.Detailed petrography,mineral chemistry,metamorphic evolution and zircon U-Pb dating are presented for felsic granulite and two-pyroxene granulite from the Yishui complex to contribute to new insights into the Neoarchean tectonic evolution of the North China Craton.Three mineral assemblages are recognized for these granulite samples,including the prograde(M1),peak(M2)and retrograde(M3)mineral assemblages.Conventional geothermobarometry and phase equilibrium modeling yield P-T conditions of 6.5-10.9 kbar/718-839℃ for the peak metamorphism,which define a medium-pressure granulite-facies metamorphism occurred at middle to lower crust.Anticlockwise P-T paths with near-isobaric cooling(IBC)retrograde segments were reconstructed.Zircon LA-ICP-MS U-Pb dating suggests that the protolith of the felsic granulite was emplaced at 2541±7 Ma and the subsequent medium-pressure granulite-facies metamorphism occurred at 2518-2494 Ma.A two-stage mantle plume related crustal-scale sagduction geodynamic regime is proposed in the western Shandong terrane in the Neoarchean.
基金Project supported by the Natural Science Foundation of Hainan Province,China(Grant Nos.621RC741 and 622RC668)。
文摘Based on the Kraus operator-sum representation of the analytical solution of the diffusion equation,we obtain the evolution of a general linear state in the diffusion channel.Also,we study the quantum statistical properties of the initial general linear state and its von-Neumann entropy evolution in the diffusion channel,especially find that the entropy evolution is influenced by the diffusion noise and the thermal parameter but without the displacement.
基金funded by the Natural Science Foundation of Shandong Province(ZR2020MC144)the Scientific Research Training Program for Undergraduates of Qufu Normal University(XJ2024016).
文摘Strontium has similar chemical properties to calcium and has recently been recognized as a non-essential beneficial element for plants.In order to compare the effects of strontium and calcium on improving salt tolerance of Chinese cabbage during the germination stage,2,4,and 8 mmol/L of SrCl_(2),CaCl_(2) or an equimolar mixture of both were added separately to a 150 mmol/L NaCl solution.The results showed that Ca-Sr addition significantly increased seed viability,seed vigor,seed germination rate and seed germination uniformity of Chinese cabbage compared with the salt-control group.The differences in germination percentage(GP)and germination energy(GE)among the Ca-addition and Sr-addition groups were not significant,and the differences in coefficient of rate of germination(CRG),index of rate of germination(IRG)and coefficient of variation of the germination time(CVT)were relatively small,but clear differences were observed in germination index(GI),vigor index(VI)and coefficient of uniformity of germination(CUG).The results of GI and VI indicated that the higher the concentration of Ca-addition or Sr-addition,the more significant the enhancement of seed vigor.Under saline stress(150 mmol/L NaCl),the Ca-Sr co-addition outperformed Sr-treatment alone,and Ca-addition achieved the highest seed vigor at equivalent concentrations.Furthermore,all Ca-Sr treatments significantly enhanced the uniformity of Chinese cabbage sprouts exposed to 150 mM NaCl,with the best uniformity improved by the addition of 2 and 4 mmol/L SrCl_(2).Ca-Sr treatments increased the salt tolerance of Chinese cabbage sprouts during the germination stage mainly because the Ca2+and Sr2+significantly enhanced plasma membrane stability and reduced oxidative stress(as indicated by decreased contents of malondialdehyde and O2⋅-contents)in sprouts.The decrease of soluble sugar and proline content caused by Ca-Sr addition implies that elevated levels of these osmolytes were not the primary contributors to improved seed germinability in Chinese cabbage.These findings demonstrate that Sr is a beneficial element for enhancing salt tolerance in plants,laying a theoretical foundation for the development and application of strontium in agriculture.
基金support of National Natural Science Foundation of China(No.21906124)Natural Science Foundation of Hubei Province(No.2017CFB220)。
文摘Metal-organic frameworks(MOFs)with superior physicochemical properties have great potential for applications in chromatographic separation.However,currently popular methods for the synthesis of MOFbased silica composite materials usually require the use of harmful organic solvents and long-term hightemperature sealing reactions.In order to respond to the needs of green chromatography,it is urgent to develop a new green organic-solvent-free strategy for the synthesis of MOF@SiO_(2)composites.MIP-202 is a zirconium-MOF constructed from zirconium ion and l-aspartic acid,which features green synthesis as well as good hydrolytic stability and chemical stability.In this paper,SiO_(2)-NH_(2) was first prepared in a hydrophilic deep eutectic solvent,and then an amino acid-based MOF material(MIP-202)was modified on the surface of the SiO_(2)-NH_(2) in an aqueous solution to obtain a MIP-202@SiO_(2) composite material.The multi-mode separation performance of MIP-202@SiO_(2) as a promising liquid chromatographic stationary phase was particularly evaluated and the separation mechanisms were discussed.The MIP-202@SiO_(2) column exhibited excellent separation ability for aromatic positional isomers.In addition,chiral enantiomers and hydrophilic analytes were also satisfactorily detected and separated.This work provides a new approach for the facile synthesis of MOF-based liquid chromatographic separation material by using green deep eutectic solvent and water as the reaction media.
