Acid production with flue gas is a complex nonlinear process with multiple variables and strong coupling.The operation data is an important basis for state monitoring,optimal control,and fault diagnosis.However,the op...Acid production with flue gas is a complex nonlinear process with multiple variables and strong coupling.The operation data is an important basis for state monitoring,optimal control,and fault diagnosis.However,the operating environment of acid production with flue gas is complex and there is much equipment.The data obtained by the detection equipment is seriously polluted and prone to abnormal phenomena such as data loss and outliers.Therefore,to solve the problem of abnormal data in the process of acid production with flue gas,a data cleaning method based on improved random forest is proposed.Firstly,an outlier data recognition model based on isolation forest is designed to identify and eliminate the outliers in the dataset.Secondly,an improved random forest regression model is established.Genetic algorithm is used to optimize the hyperparameters of the random forest regression model.Then the optimal parameter combination is found in the search space and the trend of data is predicted.Finally,the improved random forest data cleaning method is used to compensate for the missing data after eliminating abnormal data and the data cleaning is realized.Results show that the proposed method can accurately eliminate and compensate for the abnormal data in the process of acid production with flue gas.The method improves the accuracy of compensation for missing data.With the data after cleaning,a more accurate model can be established,which is significant to the subsequent temperature control.The conversion rate of SO_(2) can be further improved,thereby improving the yield of sulfuric acid and economic benefits.展开更多
Research on two-dimensional(2D) materials has been explosively increasing in last seventeen years in varying subjects including condensed matter physics, electronic engineering, materials science, and chemistry since ...Research on two-dimensional(2D) materials has been explosively increasing in last seventeen years in varying subjects including condensed matter physics, electronic engineering, materials science, and chemistry since the mechanical exfoliation of graphene in 2004. Starting from graphene, 2D materials now have become a big family with numerous members and diverse categories. The unique structural features and physicochemical properties of 2D materials make them one class of the most appealing candidates for a wide range of potential applications. In particular, we have seen some major breakthroughs made in the field of 2D materials in last five years not only in developing novel synthetic methods and exploring new structures/properties but also in identifying innovative applications and pushing forward commercialisation. In this review, we provide a critical summary on the recent progress made in the field of 2D materials with a particular focus on last five years. After a brief backgroundintroduction, we first discuss the major synthetic methods for 2D materials, including the mechanical exfoliation, liquid exfoliation, vapor phase deposition, and wet-chemical synthesis as well as phase engineering of 2D materials belonging to the field of phase engineering of nanomaterials(PEN). We then introduce the superconducting/optical/magnetic properties and chirality of 2D materials along with newly emerging magic angle 2D superlattices. Following that, the promising applications of 2D materials in electronics, optoelectronics, catalysis, energy storage, solar cells, biomedicine, sensors, environments, etc. are described sequentially. Thereafter, we present the theoretic calculations and simulations of 2D materials. Finally, after concluding the current progress, we provide some personal discussions on the existing challenges and future outlooks in this rapidly developing field.展开更多
Power grid construction projects are distinguished by their wide variety,high investment,long payback period,and close relation to national development and human welfare.To improve the investment accuracy in such proj...Power grid construction projects are distinguished by their wide variety,high investment,long payback period,and close relation to national development and human welfare.To improve the investment accuracy in such projects and effectively prevent investment risks,this paper proposes an investment optimization decision-making method for multiple power grid construction projects under a certain investment scale.Firstly,an in-depth analysis of the characteristics and development requirements of China’s power grid projects was performed.Thereafter,the time sequence and holographic method was adopted to conduct multi-dimensional,multi-perspective risk assessment of different parts of power grid projects,and a holographic risk assessment index system was developed.Moreover,an investment decision model considering the comprehensive risk based on combination weighting was developed according to the output and input of power grid construction projects.A new combination weighting optimization method that takes into account the investment willingness of enterprises was designed to improve the current weighting evaluation methods.Finally,the validity and applicability of the proposed evaluation method were verified by case examples.展开更多
A feasible neuron model can be effective to estimate the mode transition in neural activities in a complex electromagnetic environment.When neurons are exposed to electromagnetic field,the continuous magnetization and...A feasible neuron model can be effective to estimate the mode transition in neural activities in a complex electromagnetic environment.When neurons are exposed to electromagnetic field,the continuous magnetization and polarization can generate nonlinear effect on the exchange and propagation of ions in the cell,and then the firing patterns can be regulated completely.The conductivity of ion channels can be affected by the temperature and the channel current is adjusted for regulating the excitability of neurons.In this paper,a phototube and a thermistor are used to the functions of neural circuit.The phototube is used to capture external illumination for energy injection,and a continuous signal source is obtained.The thermistor is used to percept the changes of temperature,and the channel current is changed to adjust the excitability of neuron.This functional neural circuit can encode the external heat(temperature)and illumination excitation,and the dynamics of neural activities is investigated in detail.The photocurrent generated in the phototube can be used as a signal source for the neural circuit,and the thermistor is used to estimate the conduction dependence on the temperature for neurons under heat effect.Bifurcation analysis and Hamilton energy are calculated to explore the mode selection.It is found that complete dynamical properties of biological neurons can be reproduced in spiking,bursting,and chaotic firing when the phototube is activated as voltage source.The functional neural circuit mainly presents spiking states when the photocurrent is handled as a stable current source.Gaussian white noise is imposed to detect the occurrence of coherence resonance.This neural circuit can provide possible guidance for investigating dynamics of neural networks and potential application in designing sensitive sensors.展开更多
BACKGROUND:Estrogen has been clinically demonstrated to attenuate ischemic brain injury. However,the precise mechanisms remain controversial. OBJECTIVE:To investigate the effects of estradiol on angiopoietin-1 mRNA an...BACKGROUND:Estrogen has been clinically demonstrated to attenuate ischemic brain injury. However,the precise mechanisms remain controversial. OBJECTIVE:To investigate the effects of estradiol on angiopoietin-1 mRNA and Bcl-2 expression, as well as apoptosis and cerebral blood flow,in ovariectomized rats with focal cerebral ischemia following reperfusion. DESIGN,TIME AND SETTING:Randomized,controlled,animal experiment.The study was performed at the Central Laboratory,Chongqing Medical University from September to December 2005. MATERIALS:Estradiol benzoate was purchased from Shanghai Ninth Pharmaceutical Factory; com oil was purchased from Walmart Supercenter;TUNEL kit,rabbit anti-rat Bcl-2 polyclonal antibody,and biotin-labeled goat anti-rabbit antibody were purchased from Wuhan Boster,China. METHODS:Healthy,female,6-month-old Wistar rats-wild-type and estrogen alpha receptor gene knockout(ERKO)-were randomly divided into estradiol and control groups with 25 animals in each group.The rats were intramuscularly injected with estradiol benzoate(100μg/kg per day) at 30 days following bilateral ovariectomy or corn oil(1 mL/kg per day) for seven consecutive days.Following administration,cerebral ischemia/reperfusion models were established using the right middle cerebral artery occlusion(MCAO) method.After 30 minutes of MCAO,estradiol and control groups were separately injected with estradiol benzoate and corn oil with the above-mentioned doses. MAIN OUTCOME MEASURES:Cell apoptosis was determined by TUNEL;angiopoietin-1 mRNA and Bcl-2 gene expression was determined,respectively,by immunohistochemical staining and RT-PCR.In addition,changes in cerebral blood flow were measured by laser Doppler flowmetry. RESULTS:Changes in angiopoietin-1 mRNA and cerebral blood flow in estradiol-treated,wild-type, MCAO rats following ischemia/reperfusion were greater than in control rats(P<0.01 or 0.05). However,no significant difference was observed between estradiol-treated ERKO MCAO rats and control rats.In addition,estradiol-treated wild-type and ERKO MCAO rats exhibited significantly increased Bcl-2 expression(P<0.05) and decreased number of apoptotic cells in brain tissues compared with control groups(P<0.05). CONCLUSION:Estradiol upregulated angiopoietin-1 mRNA and Bcl-2 expression,suggesting that estradiol might be involved in protective mechanisms of cerebral ischemia/reperfusion injury.展开更多
To address the problem of using fixed feature and single apparent model which is difficult to adapt to the complex scenarios, a Kernelized correlation filter target tracking algorithm based on online saliency feature ...To address the problem of using fixed feature and single apparent model which is difficult to adapt to the complex scenarios, a Kernelized correlation filter target tracking algorithm based on online saliency feature selection and fusion is proposed. It combined the correlation filter tracking framework and the salient feature model of the target. In the tracking process, the maximum Kernel correlation filter response values of different feature models were calculated respectively, and the response weights were dynamically set according to the saliency of different features. According to the filter response value, the final target position was obtained, which improves the target positioning accuracy. The target model was dynamically updated in an online manner based on the feature saliency measurement results. The experimental results show that the proposed method can effectively utilize the distinctive feature fusion to improve the tracking effect in complex environments.展开更多
While enol-keto tautomerism has attracted great interest in Schiff bases and related compounds in solution and crystal states,the self-assembly of energy-unfavored keto form were scarcely investigated.Here,we report a...While enol-keto tautomerism has attracted great interest in Schiff bases and related compounds in solution and crystal states,the self-assembly of energy-unfavored keto form were scarcely investigated.Here,we report a keto-form directed self-assembly of a naphthalene-attached enantiomeric N-salicylideneanil analog L/DGG-Nap accompanied with a significantly amplified circularly polarized luminescence(CPL).It was found that LGG-Nap exists as a mixture of enol and keto form in monomer at a diluted toluene solution.The increment of the concentrations leads to the formation of predominated keto form,which subsequently triggers the self-assembly.Cryo-transmission electron microscopy(Cryo-TEM)revealed that a hierarchical assembly process happened upon increasing the concentration of LGG-Nap in toluene.Individual nanofibers formed at 1×10-4 mol/L and transferred into helical nanofiber bundles in 5×10-3 mol/L.Interestingly,while these is nearly no circular dichroism(CD)or CPL in the monomeric solution,the assembly showed strong CD and CPL.Remarkably,the dissymmetry factor(glum)was significantly amplified from zero in solution through the 0.005 in individual nanofiber to 0.1 in nanofiber bundles.This work demonstrates that the enol-keto tautomerism can be broken and trigger the self-assembly upon increasing the concentration,which can subsequently direct the chiral self-assembly and significantly amplify the dissymmetry factor of assembled CPL materials.展开更多
We present a quantitative mean annual air temperature(MAAT)record spanning the past 4700 years based on the analysis of branched glycerol dialkyl glycerol tetraethers(brGDGTs)from a sediment core from Xiada Co,an alpi...We present a quantitative mean annual air temperature(MAAT)record spanning the past 4700 years based on the analysis of branched glycerol dialkyl glycerol tetraethers(brGDGTs)from a sediment core from Xiada Co,an alpine lake on the western Tibetan Plateau(TP).The record indicates a relatively stable and warm MAAT until 2200 cal yr BP;subsequently,the MAAT decreased by~4.4℃ at~2100 cal yr BP and maintained a cooling trend until the present day,with centennial-scale oscillations centered at~800 cal yr BP,~600 cal yr BP,and~190-170 cal yr BP.MAAT decreased abruptly at~500-300 cal yr BP and reached its minimum for the past 4700 years.We assessed the representativeness of our record by comparing it with 15 published paleotemperature records from the TP spanning the past~5000 years.The results show divergent temperature variations,including a gradual cooling trend,a warming trend,and no clear trend.We suggest that these discrepancies could be caused by factors such as the seasonality of the temperature proxies,the length of the freezing season of the lakes,the choice of proxy-temperature calibrations,and chronological errors.Our results highlight the need for more high-quality paleotemperature reconstructions with unambiguous climatic significance,clear seasonality,site-specific calibration,and robust dating,to better understand the processes,trends,and mechanisms of Holocene temperature changes on the TP.展开更多
The research on circularly polarized luminescence(CPL)has garnered significant attention in recent years due to its many potential applications.One aspect of this research involves the pursuit of chiral materials that...The research on circularly polarized luminescence(CPL)has garnered significant attention in recent years due to its many potential applications.One aspect of this research involves the pursuit of chiral materials that posess both high luminescence efficiency and dissymmetry factors.The investigation of CPL behavior is of paramount importance because the structural information of chiral luminescent systems in the excited state can be uncovered.The objective of this review is to offer a comprehensive overview of the latest advancements in the CPL research field,with a particular focus on the development of chiral emissive materials,including organic,inorganic,and hybrid substances.Furthermore,this review outlines the recent applications of these materials in areas such as displays,photoelectric devices,anticounterfeiting measures,and sensors.Finally,we highlight the primary challenges and potential prospects of CPL materials.Our aspiration is that this endeavor will contribute new perspectives and insights that further advancements in related research fields.展开更多
The chiral self-assembly of functional molecules,polymers and clus-ters into nanoscale objects with well-defined ordering,asymmetry and in some cases out-of-equilibrium characteristics is an important strategy to fabr...The chiral self-assembly of functional molecules,polymers and clus-ters into nanoscale objects with well-defined ordering,asymmetry and in some cases out-of-equilibrium characteristics is an important strategy to fabricate novel materials[1],which might address key challenges at the heart of energy,environmental and biomedical applications.In recent years,subsequent utilization of these nanoscale units as new building blocks to fabricate advanced structures and realize more complex func-tions like those in the biology systems has aroused interests.These at-tempts are originated from the concept of molecular nanotechnology but have gone beyond its boundaries towards the breakthroughs of self-assembled machines,advanced nanoarchitectonics and molecular nanotopology[2,3].展开更多
Porphyrins are among the most important macrocycles because they perform many essential functions in living systems and serve as building blocks in many functional materials.Incorporating the chirality into porphyrins...Porphyrins are among the most important macrocycles because they perform many essential functions in living systems and serve as building blocks in many functional materials.Incorporating the chirality into porphyrins can aid biomimetic research and the exploration of new functional materials.In this review,recent developments in chiral porphyrin assemblies are highlighted.The review is mainly divided into two sections:the different strategies for constructing chiral porphyrin assemblies and the applications.The formation of chiral porphyrin assemblies can be from porphyrin molecules substituted with chiral groups;achiral porphyrins induced by chiral additives and spontaneous deracemizations of achiral porphyrins during the assemblies.We also provide an overview of the applications of chiral porphyrin assemblies in chiral sensing,asymmetry catalysis,circularly polarized luminescence,and so on.The further challenge in the field is discussed.展开更多
The research in circularly polarized luminescence has attracted wide interest in recent years.Efforts on one side are directed toward the development of chiral materials with both high luminescence efficiency and diss...The research in circularly polarized luminescence has attracted wide interest in recent years.Efforts on one side are directed toward the development of chiral materials with both high luminescence efficiency and dissymmetry factors,and on the other side,are focused on the exploitations of these materials in optoelectronic applications.This review summarizes the recent frontiers(mostly within five years)in the research in circularly polarized luminescence,including the development of chiral emissive materials based on organic small molecules,compounds with aggregation-induced emissions,supramolecular assemblies,liquid crystals and liquids,polymers,metal-ligand coordination complexes and assemblies,metal clusters,inorganic nanomaterials,and photon upconversion systems.In addition,recent applications of related materials in organic light-emitting devices,circularly polarized light detectors,and organic lasers and displays are also discussed.展开更多
The general approach for fabricating solid-state materials showing circularly polarized luminescence(CPL)is still in its challenge.In this work,chiral metal-organic frameworks(MOFs)with full-color and white-color circ...The general approach for fabricating solid-state materials showing circularly polarized luminescence(CPL)is still in its challenge.In this work,chiral metal-organic frameworks(MOFs)with full-color and white-color circularly polarized light emission are firstly achieved through a host-guest emitter-loading strategy.Chiral zeolitic imidazolate frameworks(ZIFs,a class of MOFs)are fabricated by a facile and simple mixed-ligand coassembly pathway.Meantime,achiral dyes,quantum dots(QDs),and upconversion nanoparticles(UCNPs)are easily loaded into the chiral ZIFs during the synthetic process.Size-matched dyes can be solely encapsulated into the chiral cages of ZIF,resulting in induced CPL and enhanced luminescence efficiency in solid-state ZIF⊃dye composites.Large-sized QDs,after embedding into the gap of the ZIF particles,also exhibited intense CPL activity.Furthermore,through modulating the blending ratio of colored dyes or QDs in chiral ZIFs,white light-emitting ZIFs with circular polarization could be constructed in a solid state.In addition,through loading rare earth element-based upconversion nanoparticles(UCNPs)into chiral ZIFs,upconverted CPL(UC-CPL)could be achieved with a high dissymmetry factor(glum).Thus,various achiral luminophores were endowed with CPL upon coupling with chiral ZIFs,which significantly deepened and enlarged the research scope of the chiroptical materials in a solid state.展开更多
Removal of Pb^(2+)and biodegradation of organophosphorus have been both widely investigated respectively. However, bio-remediation of both Pb^(2+)and organophosphorus still remains largely unexplored. Bacillus subtili...Removal of Pb^(2+)and biodegradation of organophosphorus have been both widely investigated respectively. However, bio-remediation of both Pb^(2+)and organophosphorus still remains largely unexplored. Bacillus subtilis FZUL-33, which was isolated from the sediment of a lake, possesses the capability for both biomineralization of Pb^(2+)and biodegradation of acephate. In the present study, both Pb^(2+)and acephate were simultaneously removed via biodegradation and biomineralization in aqueous solutions.Batch experiments were conducted to study the influence of p H, interaction time and Pb^(2+)concentration on the process of removal of Pb2+. At the temperature of 25°C, the maximum removal of Pb^(2+)by B. subtilis FZUL-33 was 381.31 ± 11.46 mg/g under the conditions of p H 5.5, initial Pb^(2+)concentration of 1300 mg/L, and contact time of 10 min. Batch experiments were conducted to study the influence of acephate on removal of Pb^(2+)and the influence of Pb2+on biodegradation of acephate by B. subtilis FZUL-33. In the mixed system of acephate–Pb2+, the results show that biodegradation of acephate by B. subtilis FZUL-33 released PO43+, which promotes mineralization of Pb2+. The process of biodegradation of acephate was affected slightly when the concentration of Pb2+was below 100 mg/L. Based on the results, it can be inferred that the B. subtilis FZUL-33 plays a significant role in bio-remediation of organophosphorus-heavy metal compound contamination.展开更多
Environmental catalysis has drawn a great deal ofattention due to its clean ways to produce useful chemicals or carry out some chemical processes.Photocatalysis and electrocatalysis play important roles in these field...Environmental catalysis has drawn a great deal ofattention due to its clean ways to produce useful chemicals or carry out some chemical processes.Photocatalysis and electrocatalysis play important roles in these fields.They can decompose and remove organic pollutants from the aqueous environment,and prepare some fine chemicals.Moreover,they also can carry out some important reactions,such as 02 reduction reaction(ORR),O2 evolution reaction(OER),H2 evolution reaction(HER),CO2 reduction reaction(C02 RR),and N2 fixation(NRR).For catalytic reactions,it is the key to develop high-performance catalysts to meet the demand fortargeted reactions.In recentyears,two-dimensional(2 D) materials have attracted great interest in environmental catalysis due to their unique layered structures,which offer us to make use of their electronic and structural characteristics.Great progress has been made so far,including graphene,black phosphorus,oxides,layered double hydroxides(LDHs),chalcogenides,bismuth-based layered compounds,MXenes,metal organic frameworks(MOFs),covalent organic frameworks(COFs),and others.This content drives us to invite many famous groups in these fields to write the roadmap on two-dimensional nanomaterials for environmental catalysis.We hope that this roadmap can give the useful guidance to researchers in future researches,and provide the research directions.展开更多
The prevalent presence of fluoroquinolone antibiotics in aquatic environments has attracted considerable attention because of their harmful effects on humans and the ecological environment.Magnesium hydroxide nanocrys...The prevalent presence of fluoroquinolone antibiotics in aquatic environments has attracted considerable attention because of their harmful effects on humans and the ecological environment.Magnesium hydroxide nanocrystals were found to act as a simple and effective adsorbent to remove low-concentration ciprofloxacin(CIP)in aqueous solution.The as-prepared Mg(OH)2 nanocrystals exhibited excellent CIP adsorption performance and high selectivity toward CIP molecules compared with other antibiotics or aromatics,e.g.,norfloxacin(NOR)and eosin B(EB).The adsorbent showed pH-dependent adsorption,indicating that the adsorption process is probably dominated by an electrostatic interaction mechanism.In addition,structural analysis of the adsorbent indicated that coordination and hydrogen bonding between CIP and Mg(OH)2 nanocrystal might also be involved in the adsorption process.Moreover,the adsorbent could be easily recovered by pyrolysis and hydration without significant reduction of adsorption capacity.The superior adsorption behavior of Mg(OH)2 nanocrystal indicates that it may serve as a potential adsorbent material candidate for the selective removal of CIP from aquatic environments.展开更多
This report investigated the ordering of the alky chain of sphingomyelin(SMs) monolayers induced by cholesterol at the air/water interface using high-resolution broadband sum frequency generation vibrational spectrosc...This report investigated the ordering of the alky chain of sphingomyelin(SMs) monolayers induced by cholesterol at the air/water interface using high-resolution broadband sum frequency generation vibrational spectroscopy(HR-BB-SFG-VS). The SFG spectra of the three nature sphingomyelin/cholesterol mixture monolayers with two concentrations of the cholesterol at the air/water interface are performed under different polarization combination. A new resolved CH_2 symmetric stretching(d^+, ～2834 cm^(-1))and the CH3 symmetric stretching(r^+,～2874 cm^(-1)) mode are applied to characterize the conformational order in the sphingomyelin/cholesterol mixture monolayers. It was found that the cholesterol make the sphingosine backbones more conformational order. During this process, the conformational order of the N-linked acyl chain remains unaltered. Moreover, the sphingosine backbones of SMs have much larger contributions to gauche defects of SMs than one in the N-linked acyl chain. These results presented here not only shed lights on understanding of the interactions of sphingomyelin molecules with cholesterol molecules at interface but also demonstrates the ability of HR-BB-SFG to probe such complicated molecular systems.展开更多
Plasmonic chiroptical materials,coupled by chirality and surface plasmons,have been attracting great interest due to their potential applications,such as photonics,chiral recognition,asymmetric catalysis and biosensin...Plasmonic chiroptical materials,coupled by chirality and surface plasmons,have been attracting great interest due to their potential applications,such as photonics,chiral recognition,asymmetric catalysis and biosensing.Herein,we constructed a new chiral plasmonic nanostructure—helically grooved gold nanoarrows(HeliGNAs)by introducing L-/Dcysteine(L-/D-Cys)during the growth of the gold nanoarrows(GNAs).The variation of the concentration of L-/D-Cys leads to the HeliGNAs with a tunable plasmonic circular dichroism(PCD).展开更多
基金supported by the National Natural Science Foundation of China(61873006)Beijing Natural Science Foundation(4204087,4212040).
文摘Acid production with flue gas is a complex nonlinear process with multiple variables and strong coupling.The operation data is an important basis for state monitoring,optimal control,and fault diagnosis.However,the operating environment of acid production with flue gas is complex and there is much equipment.The data obtained by the detection equipment is seriously polluted and prone to abnormal phenomena such as data loss and outliers.Therefore,to solve the problem of abnormal data in the process of acid production with flue gas,a data cleaning method based on improved random forest is proposed.Firstly,an outlier data recognition model based on isolation forest is designed to identify and eliminate the outliers in the dataset.Secondly,an improved random forest regression model is established.Genetic algorithm is used to optimize the hyperparameters of the random forest regression model.Then the optimal parameter combination is found in the search space and the trend of data is predicted.Finally,the improved random forest data cleaning method is used to compensate for the missing data after eliminating abnormal data and the data cleaning is realized.Results show that the proposed method can accurately eliminate and compensate for the abnormal data in the process of acid production with flue gas.The method improves the accuracy of compensation for missing data.With the data after cleaning,a more accurate model can be established,which is significant to the subsequent temperature control.The conversion rate of SO_(2) can be further improved,thereby improving the yield of sulfuric acid and economic benefits.
文摘Research on two-dimensional(2D) materials has been explosively increasing in last seventeen years in varying subjects including condensed matter physics, electronic engineering, materials science, and chemistry since the mechanical exfoliation of graphene in 2004. Starting from graphene, 2D materials now have become a big family with numerous members and diverse categories. The unique structural features and physicochemical properties of 2D materials make them one class of the most appealing candidates for a wide range of potential applications. In particular, we have seen some major breakthroughs made in the field of 2D materials in last five years not only in developing novel synthetic methods and exploring new structures/properties but also in identifying innovative applications and pushing forward commercialisation. In this review, we provide a critical summary on the recent progress made in the field of 2D materials with a particular focus on last five years. After a brief backgroundintroduction, we first discuss the major synthetic methods for 2D materials, including the mechanical exfoliation, liquid exfoliation, vapor phase deposition, and wet-chemical synthesis as well as phase engineering of 2D materials belonging to the field of phase engineering of nanomaterials(PEN). We then introduce the superconducting/optical/magnetic properties and chirality of 2D materials along with newly emerging magic angle 2D superlattices. Following that, the promising applications of 2D materials in electronics, optoelectronics, catalysis, energy storage, solar cells, biomedicine, sensors, environments, etc. are described sequentially. Thereafter, we present the theoretic calculations and simulations of 2D materials. Finally, after concluding the current progress, we provide some personal discussions on the existing challenges and future outlooks in this rapidly developing field.
基金supported by the State Grid Science and Technology Project (SGTYHT/16-JS-198)
文摘Power grid construction projects are distinguished by their wide variety,high investment,long payback period,and close relation to national development and human welfare.To improve the investment accuracy in such projects and effectively prevent investment risks,this paper proposes an investment optimization decision-making method for multiple power grid construction projects under a certain investment scale.Firstly,an in-depth analysis of the characteristics and development requirements of China’s power grid projects was performed.Thereafter,the time sequence and holographic method was adopted to conduct multi-dimensional,multi-perspective risk assessment of different parts of power grid projects,and a holographic risk assessment index system was developed.Moreover,an investment decision model considering the comprehensive risk based on combination weighting was developed according to the output and input of power grid construction projects.A new combination weighting optimization method that takes into account the investment willingness of enterprises was designed to improve the current weighting evaluation methods.Finally,the validity and applicability of the proposed evaluation method were verified by case examples.
基金Project supported by the National Natural Science Foundation of China(Grant No.11672122).
文摘A feasible neuron model can be effective to estimate the mode transition in neural activities in a complex electromagnetic environment.When neurons are exposed to electromagnetic field,the continuous magnetization and polarization can generate nonlinear effect on the exchange and propagation of ions in the cell,and then the firing patterns can be regulated completely.The conductivity of ion channels can be affected by the temperature and the channel current is adjusted for regulating the excitability of neurons.In this paper,a phototube and a thermistor are used to the functions of neural circuit.The phototube is used to capture external illumination for energy injection,and a continuous signal source is obtained.The thermistor is used to percept the changes of temperature,and the channel current is changed to adjust the excitability of neuron.This functional neural circuit can encode the external heat(temperature)and illumination excitation,and the dynamics of neural activities is investigated in detail.The photocurrent generated in the phototube can be used as a signal source for the neural circuit,and the thermistor is used to estimate the conduction dependence on the temperature for neurons under heat effect.Bifurcation analysis and Hamilton energy are calculated to explore the mode selection.It is found that complete dynamical properties of biological neurons can be reproduced in spiking,bursting,and chaotic firing when the phototube is activated as voltage source.The functional neural circuit mainly presents spiking states when the photocurrent is handled as a stable current source.Gaussian white noise is imposed to detect the occurrence of coherence resonance.This neural circuit can provide possible guidance for investigating dynamics of neural networks and potential application in designing sensitive sensors.
基金Supported by:the Natural Science Foundation of Chongqing,No. CSTC2006EB5030
文摘BACKGROUND:Estrogen has been clinically demonstrated to attenuate ischemic brain injury. However,the precise mechanisms remain controversial. OBJECTIVE:To investigate the effects of estradiol on angiopoietin-1 mRNA and Bcl-2 expression, as well as apoptosis and cerebral blood flow,in ovariectomized rats with focal cerebral ischemia following reperfusion. DESIGN,TIME AND SETTING:Randomized,controlled,animal experiment.The study was performed at the Central Laboratory,Chongqing Medical University from September to December 2005. MATERIALS:Estradiol benzoate was purchased from Shanghai Ninth Pharmaceutical Factory; com oil was purchased from Walmart Supercenter;TUNEL kit,rabbit anti-rat Bcl-2 polyclonal antibody,and biotin-labeled goat anti-rabbit antibody were purchased from Wuhan Boster,China. METHODS:Healthy,female,6-month-old Wistar rats-wild-type and estrogen alpha receptor gene knockout(ERKO)-were randomly divided into estradiol and control groups with 25 animals in each group.The rats were intramuscularly injected with estradiol benzoate(100μg/kg per day) at 30 days following bilateral ovariectomy or corn oil(1 mL/kg per day) for seven consecutive days.Following administration,cerebral ischemia/reperfusion models were established using the right middle cerebral artery occlusion(MCAO) method.After 30 minutes of MCAO,estradiol and control groups were separately injected with estradiol benzoate and corn oil with the above-mentioned doses. MAIN OUTCOME MEASURES:Cell apoptosis was determined by TUNEL;angiopoietin-1 mRNA and Bcl-2 gene expression was determined,respectively,by immunohistochemical staining and RT-PCR.In addition,changes in cerebral blood flow were measured by laser Doppler flowmetry. RESULTS:Changes in angiopoietin-1 mRNA and cerebral blood flow in estradiol-treated,wild-type, MCAO rats following ischemia/reperfusion were greater than in control rats(P<0.01 or 0.05). However,no significant difference was observed between estradiol-treated ERKO MCAO rats and control rats.In addition,estradiol-treated wild-type and ERKO MCAO rats exhibited significantly increased Bcl-2 expression(P<0.05) and decreased number of apoptotic cells in brain tissues compared with control groups(P<0.05). CONCLUSION:Estradiol upregulated angiopoietin-1 mRNA and Bcl-2 expression,suggesting that estradiol might be involved in protective mechanisms of cerebral ischemia/reperfusion injury.
基金the National Natural Science Foundation (61472196, 61672305)Natural Science Foundation of Shandong Province (BS2015DX010, ZR2015FM012)Key Research and Development Foundation of Shandong Province (2017GGX10133).
文摘To address the problem of using fixed feature and single apparent model which is difficult to adapt to the complex scenarios, a Kernelized correlation filter target tracking algorithm based on online saliency feature selection and fusion is proposed. It combined the correlation filter tracking framework and the salient feature model of the target. In the tracking process, the maximum Kernel correlation filter response values of different feature models were calculated respectively, and the response weights were dynamically set according to the saliency of different features. According to the filter response value, the final target position was obtained, which improves the target positioning accuracy. The target model was dynamically updated in an online manner based on the feature saliency measurement results. The experimental results show that the proposed method can effectively utilize the distinctive feature fusion to improve the tracking effect in complex environments.
基金National Natural Science foundation of China(Nos.21861132002,21773043,21973020 and 21890734).
文摘While enol-keto tautomerism has attracted great interest in Schiff bases and related compounds in solution and crystal states,the self-assembly of energy-unfavored keto form were scarcely investigated.Here,we report a keto-form directed self-assembly of a naphthalene-attached enantiomeric N-salicylideneanil analog L/DGG-Nap accompanied with a significantly amplified circularly polarized luminescence(CPL).It was found that LGG-Nap exists as a mixture of enol and keto form in monomer at a diluted toluene solution.The increment of the concentrations leads to the formation of predominated keto form,which subsequently triggers the self-assembly.Cryo-transmission electron microscopy(Cryo-TEM)revealed that a hierarchical assembly process happened upon increasing the concentration of LGG-Nap in toluene.Individual nanofibers formed at 1×10-4 mol/L and transferred into helical nanofiber bundles in 5×10-3 mol/L.Interestingly,while these is nearly no circular dichroism(CD)or CPL in the monomeric solution,the assembly showed strong CD and CPL.Remarkably,the dissymmetry factor(glum)was significantly amplified from zero in solution through the 0.005 in individual nanofiber to 0.1 in nanofiber bundles.This work demonstrates that the enol-keto tautomerism can be broken and trigger the self-assembly upon increasing the concentration,which can subsequently direct the chiral self-assembly and significantly amplify the dissymmetry factor of assembled CPL materials.
基金financially supported by the National Natural Science Foundation of China(Grant No.41901105)the Research and Practice Project of Teaching Reform in universities of Henan Province(No.2022SYJXLX062)+2 种基金the Key Scientific and Technological Research Project of Henan Province(No.222102320128)the Training Plan of young backbone teachers in Henan Colleges and universities(Nos.2020GGJS158,2023GGJS096)the Nanhu Scholars Program for Young Scholars of XYNU.
文摘We present a quantitative mean annual air temperature(MAAT)record spanning the past 4700 years based on the analysis of branched glycerol dialkyl glycerol tetraethers(brGDGTs)from a sediment core from Xiada Co,an alpine lake on the western Tibetan Plateau(TP).The record indicates a relatively stable and warm MAAT until 2200 cal yr BP;subsequently,the MAAT decreased by~4.4℃ at~2100 cal yr BP and maintained a cooling trend until the present day,with centennial-scale oscillations centered at~800 cal yr BP,~600 cal yr BP,and~190-170 cal yr BP.MAAT decreased abruptly at~500-300 cal yr BP and reached its minimum for the past 4700 years.We assessed the representativeness of our record by comparing it with 15 published paleotemperature records from the TP spanning the past~5000 years.The results show divergent temperature variations,including a gradual cooling trend,a warming trend,and no clear trend.We suggest that these discrepancies could be caused by factors such as the seasonality of the temperature proxies,the length of the freezing season of the lakes,the choice of proxy-temperature calibrations,and chronological errors.Our results highlight the need for more high-quality paleotemperature reconstructions with unambiguous climatic significance,clear seasonality,site-specific calibration,and robust dating,to better understand the processes,trends,and mechanisms of Holocene temperature changes on the TP.
基金supported by the Chirality Major Research Plan of the National Natural Science Foundation of China(grant nos.92256304 and 92056204).
文摘The research on circularly polarized luminescence(CPL)has garnered significant attention in recent years due to its many potential applications.One aspect of this research involves the pursuit of chiral materials that posess both high luminescence efficiency and dissymmetry factors.The investigation of CPL behavior is of paramount importance because the structural information of chiral luminescent systems in the excited state can be uncovered.The objective of this review is to offer a comprehensive overview of the latest advancements in the CPL research field,with a particular focus on the development of chiral emissive materials,including organic,inorganic,and hybrid substances.Furthermore,this review outlines the recent applications of these materials in areas such as displays,photoelectric devices,anticounterfeiting measures,and sensors.Finally,we highlight the primary challenges and potential prospects of CPL materials.Our aspiration is that this endeavor will contribute new perspectives and insights that further advancements in related research fields.
基金support from the National Natural Science Foundation of China(21890734,21890730 and 21971247)Youth Innovation Promotion Association CAS(2019036)
文摘The chiral self-assembly of functional molecules,polymers and clus-ters into nanoscale objects with well-defined ordering,asymmetry and in some cases out-of-equilibrium characteristics is an important strategy to fabricate novel materials[1],which might address key challenges at the heart of energy,environmental and biomedical applications.In recent years,subsequent utilization of these nanoscale units as new building blocks to fabricate advanced structures and realize more complex func-tions like those in the biology systems has aroused interests.These at-tempts are originated from the concept of molecular nanotechnology but have gone beyond its boundaries towards the breakthroughs of self-assembled machines,advanced nanoarchitectonics and molecular nanotopology[2,3].
基金National Natural Science Foundation of China,Grant/Award Numbers:92156018,21972150,21890734CAS Project for Young Scientists in Basic Research,Grant/Award Number:YSBR-027。
文摘Porphyrins are among the most important macrocycles because they perform many essential functions in living systems and serve as building blocks in many functional materials.Incorporating the chirality into porphyrins can aid biomimetic research and the exploration of new functional materials.In this review,recent developments in chiral porphyrin assemblies are highlighted.The review is mainly divided into two sections:the different strategies for constructing chiral porphyrin assemblies and the applications.The formation of chiral porphyrin assemblies can be from porphyrin molecules substituted with chiral groups;achiral porphyrins induced by chiral additives and spontaneous deracemizations of achiral porphyrins during the assemblies.We also provide an overview of the applications of chiral porphyrin assemblies in chiral sensing,asymmetry catalysis,circularly polarized luminescence,and so on.The further challenge in the field is discussed.
基金financially supported by the National Natural Science Foundation of China(21925112,22090021,21890734,21975118,51973011,52003022,91956119,92061201,21825106,91856115,21874058,21771114,91956130)the Research Grants Council of Hong Kong(C6014-20W)the Innovation and Technology Commission(ITC-CNERC14SC01)。
文摘The research in circularly polarized luminescence has attracted wide interest in recent years.Efforts on one side are directed toward the development of chiral materials with both high luminescence efficiency and dissymmetry factors,and on the other side,are focused on the exploitations of these materials in optoelectronic applications.This review summarizes the recent frontiers(mostly within five years)in the research in circularly polarized luminescence,including the development of chiral emissive materials based on organic small molecules,compounds with aggregation-induced emissions,supramolecular assemblies,liquid crystals and liquids,polymers,metal-ligand coordination complexes and assemblies,metal clusters,inorganic nanomaterials,and photon upconversion systems.In addition,recent applications of related materials in organic light-emitting devices,circularly polarized light detectors,and organic lasers and displays are also discussed.
基金This work was supported by the National Natural Science Foundation of China(51673050 and 91856115)the Ministry of Science and Technology of the People’s Republic of China(2017YFA0206600 and 2016YFA0203400)。
文摘The general approach for fabricating solid-state materials showing circularly polarized luminescence(CPL)is still in its challenge.In this work,chiral metal-organic frameworks(MOFs)with full-color and white-color circularly polarized light emission are firstly achieved through a host-guest emitter-loading strategy.Chiral zeolitic imidazolate frameworks(ZIFs,a class of MOFs)are fabricated by a facile and simple mixed-ligand coassembly pathway.Meantime,achiral dyes,quantum dots(QDs),and upconversion nanoparticles(UCNPs)are easily loaded into the chiral ZIFs during the synthetic process.Size-matched dyes can be solely encapsulated into the chiral cages of ZIF,resulting in induced CPL and enhanced luminescence efficiency in solid-state ZIF⊃dye composites.Large-sized QDs,after embedding into the gap of the ZIF particles,also exhibited intense CPL activity.Furthermore,through modulating the blending ratio of colored dyes or QDs in chiral ZIFs,white light-emitting ZIFs with circular polarization could be constructed in a solid state.In addition,through loading rare earth element-based upconversion nanoparticles(UCNPs)into chiral ZIFs,upconverted CPL(UC-CPL)could be achieved with a high dissymmetry factor(glum).Thus,various achiral luminophores were endowed with CPL upon coupling with chiral ZIFs,which significantly deepened and enlarged the research scope of the chiroptical materials in a solid state.
基金supported by the National Basic Research Program (973) of China (No. 2014CB846003)the National Natural Science Foundation of China (Nos. 41372346 21577018)
文摘Removal of Pb^(2+)and biodegradation of organophosphorus have been both widely investigated respectively. However, bio-remediation of both Pb^(2+)and organophosphorus still remains largely unexplored. Bacillus subtilis FZUL-33, which was isolated from the sediment of a lake, possesses the capability for both biomineralization of Pb^(2+)and biodegradation of acephate. In the present study, both Pb^(2+)and acephate were simultaneously removed via biodegradation and biomineralization in aqueous solutions.Batch experiments were conducted to study the influence of p H, interaction time and Pb^(2+)concentration on the process of removal of Pb2+. At the temperature of 25°C, the maximum removal of Pb^(2+)by B. subtilis FZUL-33 was 381.31 ± 11.46 mg/g under the conditions of p H 5.5, initial Pb^(2+)concentration of 1300 mg/L, and contact time of 10 min. Batch experiments were conducted to study the influence of acephate on removal of Pb^(2+)and the influence of Pb2+on biodegradation of acephate by B. subtilis FZUL-33. In the mixed system of acephate–Pb2+, the results show that biodegradation of acephate by B. subtilis FZUL-33 released PO43+, which promotes mineralization of Pb2+. The process of biodegradation of acephate was affected slightly when the concentration of Pb2+was below 100 mg/L. Based on the results, it can be inferred that the B. subtilis FZUL-33 plays a significant role in bio-remediation of organophosphorus-heavy metal compound contamination.
基金the National Natural Science Foundation of China (Nos. 21603129 & 20871167)National Natural Science Foundation of Shanxi Province (No. 201601D202021)the Foundation of State Key Laboratory of Coal Conversion (No. J1819-903) for the financial support
文摘Environmental catalysis has drawn a great deal ofattention due to its clean ways to produce useful chemicals or carry out some chemical processes.Photocatalysis and electrocatalysis play important roles in these fields.They can decompose and remove organic pollutants from the aqueous environment,and prepare some fine chemicals.Moreover,they also can carry out some important reactions,such as 02 reduction reaction(ORR),O2 evolution reaction(OER),H2 evolution reaction(HER),CO2 reduction reaction(C02 RR),and N2 fixation(NRR).For catalytic reactions,it is the key to develop high-performance catalysts to meet the demand fortargeted reactions.In recentyears,two-dimensional(2 D) materials have attracted great interest in environmental catalysis due to their unique layered structures,which offer us to make use of their electronic and structural characteristics.Great progress has been made so far,including graphene,black phosphorus,oxides,layered double hydroxides(LDHs),chalcogenides,bismuth-based layered compounds,MXenes,metal organic frameworks(MOFs),covalent organic frameworks(COFs),and others.This content drives us to invite many famous groups in these fields to write the roadmap on two-dimensional nanomaterials for environmental catalysis.We hope that this roadmap can give the useful guidance to researchers in future researches,and provide the research directions.
基金supported by the National Natural Science Foundation of China(Nos.21577018,21477128,61376002)the National Science Foundation of Fujian Province(No.2016J01223)the Key Laboratory of Eco-materials Advanced Technology(Fuzhou University,China)
文摘The prevalent presence of fluoroquinolone antibiotics in aquatic environments has attracted considerable attention because of their harmful effects on humans and the ecological environment.Magnesium hydroxide nanocrystals were found to act as a simple and effective adsorbent to remove low-concentration ciprofloxacin(CIP)in aqueous solution.The as-prepared Mg(OH)2 nanocrystals exhibited excellent CIP adsorption performance and high selectivity toward CIP molecules compared with other antibiotics or aromatics,e.g.,norfloxacin(NOR)and eosin B(EB).The adsorbent showed pH-dependent adsorption,indicating that the adsorption process is probably dominated by an electrostatic interaction mechanism.In addition,structural analysis of the adsorbent indicated that coordination and hydrogen bonding between CIP and Mg(OH)2 nanocrystal might also be involved in the adsorption process.Moreover,the adsorbent could be easily recovered by pyrolysis and hydration without significant reduction of adsorption capacity.The superior adsorption behavior of Mg(OH)2 nanocrystal indicates that it may serve as a potential adsorbent material candidate for the selective removal of CIP from aquatic environments.
基金the National Natural Science Foundation of China(No.21227802)the National Natural Science Foundation of China(Nos. 21503235, 21673251)the ICCAS for Start-up Funding
文摘This report investigated the ordering of the alky chain of sphingomyelin(SMs) monolayers induced by cholesterol at the air/water interface using high-resolution broadband sum frequency generation vibrational spectroscopy(HR-BB-SFG-VS). The SFG spectra of the three nature sphingomyelin/cholesterol mixture monolayers with two concentrations of the cholesterol at the air/water interface are performed under different polarization combination. A new resolved CH_2 symmetric stretching(d^+, ～2834 cm^(-1))and the CH3 symmetric stretching(r^+,～2874 cm^(-1)) mode are applied to characterize the conformational order in the sphingomyelin/cholesterol mixture monolayers. It was found that the cholesterol make the sphingosine backbones more conformational order. During this process, the conformational order of the N-linked acyl chain remains unaltered. Moreover, the sphingosine backbones of SMs have much larger contributions to gauche defects of SMs than one in the N-linked acyl chain. These results presented here not only shed lights on understanding of the interactions of sphingomyelin molecules with cholesterol molecules at interface but also demonstrates the ability of HR-BB-SFG to probe such complicated molecular systems.
基金supported by the National Natural Science Foundation of China(nos.21890734,21972150,21890730,and 21773259)and the Key Research Program of Frontier Sciences,CAS,(no.QYZDJ-SSW-SLH044).
文摘Plasmonic chiroptical materials,coupled by chirality and surface plasmons,have been attracting great interest due to their potential applications,such as photonics,chiral recognition,asymmetric catalysis and biosensing.Herein,we constructed a new chiral plasmonic nanostructure—helically grooved gold nanoarrows(HeliGNAs)by introducing L-/Dcysteine(L-/D-Cys)during the growth of the gold nanoarrows(GNAs).The variation of the concentration of L-/D-Cys leads to the HeliGNAs with a tunable plasmonic circular dichroism(PCD).
