Data cleaning method for the process of acid production with flue gas based on improved random forest

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.

“可控自组装体系及其功能化”重大研究计划取得系列重要研究成果

2005年美国科学(Science)杂志在纪念该刊创办125周年之际,把"我们能推动化学自组装走多远?"列为未来最具挑战性的25个科学问题之一,受到世界各国科学家的广泛关注和重视。"十一五"期间,国家自然科学基金委员会组织多领域的科学家充分讨论和酝酿从而提出了"可控自组装体系及其功能化"重大研究计划。计划实施以来,我国科学家开拓和认识了多种新型弱相互作用力,发展了多种具有"中国标签"的新组装基元,建立了类似于有机"人名反应"的组装新方法,实现了多组分、多层次组装体的功能,构建了一批有重要科学意义和潜在实用价值的可控自组装体系,实现了从跟随到原创的跨越式发展,全面推动了我国化学可控自组装研究走向国际舞台的中心。本文介绍了"可控自组装体系及其功能化"重大研究计划的总体科学目标、总体布局和实施思路,以及该重大研究计划资助下取得的系列重要研究成果。

二维材料最新研究进展

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.

Dynamics and coherence resonance in a thermosensitive neuron driven by photocurrent

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.

Differentiation degree combination weighting method for investment decision-making risk assessment in power grid construction projects

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.

Angiopoietin-1 mRNA and Bcl-2 expression following estradiol treatment in ovariectomized rats with focal cerebral ischemia/reperfusion injury

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 ovadectomized 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; corn 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 （100 μg/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.

Kernelized Correlation Filter Target Tracking Algorithm Based on Saliency Feature Selection

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.

Keto-form directed hierarchical chiral self-assembly of Schiff base derivatives with amplified circularly polarized luminescence

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.

Evolution of template-assisted two-dimensional porphyrin chiral grating structure by directed self-assembly using chiral second harmonic generation microscopy

Directed self-assembly has been used to create micro-nano scale patterns,including chiral periodic structures of organic molecules,for potential applications in optics,photonics,metamaterials,and medical and sensing technologies.This study presents a straightforward approach for fabricating large-scale chiral grating porphyrin assemblies through template-assisted techniques.The solution of tetrakis(4-sulfonatophenyl)porphyrin(TPPS)was induced by chiral amino acids(L/D-arginine and L/D-serine)to selfassemble into highly ordered chiral grating structures with the assistance of sodium dodecyl sulfate(SDS).The structures show precise line widths(5.5μm)and gaps(18μm).Using in situ optical microscopy and second harmonic generation(SHG)microscopy,the chiral characteristics and dynamic evolution of the template-assisted self-assembly are investigated.It is found that the chirality of amino acids induced TPPS self-assembled into chiral structures and the liquid contraction interface significantly enhanced the chirality of the assemblies.This study is significant for understanding the mechanism of chiral evolution and designing novel micro-nano materials with predetermined chiral properties.

Evolution of hollow nanosphere to microtube in the self-assembly of chiral dansyl derivatives and inversed circularly polarized luminescence

Here,we designed asymmetric(m DS)and symmetrical(d DS)chiral V-shaped molecules by linking one or two dansyl groups to trans-1,2-cyclohexane diamine and investigated the solvent-regulated structural transformation and inversed circularly polarized luminescence(CPL)in the self-assemblies.Upon increasing water volume fraction(fw)in the mixed solvent of water/acetonitrile,asymmetric mDS selfassembled into hollow nanospheres and microtubes,while solid nanospheres and solid microplates were corresponding to symmetric d DS.During this transformation process,the emission of m DS and d DS was changed from yellow-green to blue and cyan color,which was ascribed to twisted intramolecular charge transfer(TICT)and locally excited(LE)fluorescence of V-shaped DS molecules.The conformation of N,Ndimethyl groups with respect to naphthalene ring also led to the transformation of structures.These tubular and platelike structures had stronger and reversed CPL signals in comparison with spheroidal structures.The chiral information of DS assembly could be effective transferred to achiral Nile red via co-assembly strategy,which endowed Nile red exhibiting inversed induced CPL signal regulated by water fraction.This work provides a method for achieving a variety of self-assembled structures with adjustable chiroptical properties.

Recent Progress of Circularly Polarized Luminescence Materials from Chinese Perspectives

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.

Late Holocene brGDGTs-based quantitative paleotemperature reconstruction from lacustrine sediments on the western Tibetan Plateau

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.

Stride the chirality transfer across length scales by merging the boundaries between solution and interfacial self-assembly

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].

Chiral porphyrin assemblies

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.

Frontiers in circularly polarized luminescence:molecular design,self-assembly,nanomaterials,and applications

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.

Dual-Mode Induction of Tunable Circularly Polarized Luminescence from Chiral Metal-Organic Frameworks

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.

2020 Roadmap on two-dimensional nanomaterials for environmental catalysis

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.

Highly efficient and selective removal of low-concentration antibiotics from aqueous solution by regenerable Mg（OH）2

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.

Helically Grooved Gold Nanoarrows: Controlled Fabrication, Superhelix, and Transcribed Chiroptical Switching

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).