山丘区小流域SCS广义单位线产汇流模型

以山丘区小流域洪水预报为研究对象,耦合改进后的美国农业部水土保持局(Soil Conservation Service,SCS)产流模型与广义单位线汇流模型,模型参数意义明确、容易确定。选取东江流域西枝江水系上游九洲水文站以上集水区域场次洪水资料,将SCS广义单位线模型与三水源新安江模型进行次洪模拟应用对比。结果表明:SCS广义单位线模型和新安江模型在研究流域场次洪水模拟中均具有适用性,洪峰、洪量及过程线均满足许可误差要求,两个模型的合格率分别为69%和77%,整体上新安江模型的模拟精度更优。新提出的SCS广义单位线模型结构简单,参数易于确定,能够提供可接受精度的模型结果,为山丘区小流域洪水预报提供新的模型选择,同时也能为广义单位线参数区域化规律研究提供支撑。

基于前期降雨指数的SCS-CN模型在三峡库区改进与应用

径流是土壤流失的主要载体,准确预测径流量对于三峡库区土壤侵蚀预报和水库安全管理至关重要。为优化径流曲线数模型(SCS-CN)中土壤前期含水量核算方法,提高径流模拟准确性,研究通过引入前期降雨指数来表征土壤含水量,并基于实测的土壤饱和含水量设定上限阈值,对SCS-CN模型进行了改进,利用忠县水土保持监测站2019-2022年的场次降雨径流监测数据评估了模型准确性,并对改进前后模型在不同降雨类型和土地利用条件的适用性进行评价。结果表明,在两种初始模型和两种改进模型中,基于MSCS-CN改进的模型(M4)对于径流深的模拟精度更高,纳什效率系数(NSE)较原始SCS-CN模型(M1)提高了134%,尤其是在前期土壤含水量达饱和状态的情况下NSE提升至0.74,引入最大前期降雨指数(APImax)作为前期降雨指数上限值能减弱以往模型对高径流事件预测值的高估。此外,改进模型M4对三峡库区主要的产流性降雨类型(高雨强)以及主要的土地利用(耕地、果园)适用性良好,有效提高了小雨量产流事件和高侵蚀风险土地利用类型的径流模拟精度(雨型Ⅱ的NSE为0.66,耕地、果园NSE分别为0.69和0.75)。总体而言,改进模型M4提高了径流模拟精度,更适合三峡库区的产流机制、土地利用类型,能为三峡库区径流预测及水土流失防治工作提供参考。

Templated synthesis of transition metal phosphide electrocatalysts for oxygen and hydrogen evolution reactions

Transition metal phosphides(TMPs)have been regarded as alternative hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)catalysts owing to their comparable activity to those of noble metal-based catalysts.TMPs have been produced in various morphologies,including hollow and porous nanostructures,which are features deemed desirable for electrocatalytic materials.Templated synthesis routes are often responsible for such morphologies.This paper reviews the latest advances and existing challenges in the synthesis of TMP-based OER and HER catalysts through templated methods.A comprehensive review of the structure-property-performance of TMP-based HER and OER catalysts prepared using different templates is presented.The discussion proceeds according to application,first by HER and further divided among the types of templates used-from hard templates,sacrificial templates,and soft templates to the emerging dynamic hydrogen bubble template.OER catalysts are then reviewed and grouped according to their morphology.Finally,prospective research directions for the synthesis of hollow and porous TMP-based catalysts,such as improvements on both activity and stability of TMPs,design of environmentally benign templates and processes,and analysis of the reaction mechanism through advanced material characterization techniques and theoretical calculations,are suggested.

基于SCS模型的登封市景观格局对地表径流的影响研究

探究登封市2003-2021年景观格局演变及其与枯、平、丰水月地表径流的关联性差异,分析景观格局指数的空间异质性,为减缓地表径流、优化景观格局提供理论支持。基于Landsat系列遥感影像,提取登封市用地类型及景观格局指数,利用SCS水文模型、Pearson相关性分析及GWR等方法研究景观格局演变对径流量的影响。结果如下:(1)登封市林地对地表径流的消减率随着雨量增加而降低,丰水月比平水月降低了33.37%;(2)登封市在不同雨量下产生的地表径流具有显著的时空差异性,其中2015-2021年快速的城市建设活动导致丰水月有26.29 km^(2)的区域出现径流深增加量超出50 mm的现象;(3)景观指数与径流量的相关性随雨量递增而逐渐显著,SPLIT、IJI和LSI在丰水月与径流的正相关系数比在平水月平均降低10.8%、12.3%和8.3%,其中林地结合度对径流的阻滞效应在平水月最强;(4)CONTAG、IJI、LSI对径流的正、负向影响力在时间和空间双重维度上存在显著差异且整体呈正向驱动,其主导驱动力随时间变化由IJI向CONTAG转变。景观格局与径流量的耦合关联性在平水月最为显著,而影响径流变化的主导驱动力在时空尺度上具有差异性,因此不同区域的防洪规划在优化整体景观格局的基础上应充分考虑优势斑块连通性对减缓径流的差异影响。

The structure-directing role of heterologous seeds in the synthesis of zeolite

Zeolites have been widely used as catalysts,ion-exchangers,and adsorbents in chemical industries,detergent industry,steel industry,glass industry,ceramic industry,medical and healthfield,and environmentalfield,and recently applied in energy storage.Seed-assisted synthesis is a very effective approach in promoting the crystallization of zeolites.In some cases,the target zeolite cannot be formed in the absence of seed zeolite.In homologous seed-assisted synthesis,the structure of the seed zeolite is the same to that of the target zeolite,while the structure of the seed zeolite is different to that of the target zeolite in the heterologous seed-assisted synthesis.In this review,we briefly summarized the heterologous seed-assisted syntheses of zeolites and analyzed the structure-directing effect of heterologous seeds and surveyed the“common composite building units(CBUs)hypothesis”and the“common secondary building units(SBUs)hypothesis”.However,both hypotheses cannot explain all observations on the heterologous seed-assisted syntheses.Finally,we proposed that the formation of the target zeolite does need nuclei with the structure of target zeolite and the formation of the nuclei of the target zeolite can be promoted by either the undissolved seed crystals with the same CBUs or SBUs to the target zeolite or by the facilitated appropriate distribution of the specific building units due to the presence of the heterologous seed that does not have any common CBUs and SBUs with the target zeolite.

Facile synthesis of hierarchical NaX zeolite from natural kaolinite for efficient Knoevenagel condensation

Zeolite catalysts have found extensive applications in the synthesis of various fine chemicals.However,the micropores of zeolites impose diffusion limitations on bulky molecules,greatly reducing the catalytic efficiency.Herein,we explore an economic and environmentally friendly method for synthesizing hierarchical NaX zeolite that exhibits improved catalytic performance in the Knoevenagel condensation reaction for producing the useful fine chemical 2-cyano-3-phenylacrylate.The synthesis was achieved via a low-temperature activation of kaolinite and subsequent in-situ transformation strategy without any template or seed.Systematic characterizations reveal that the synthesized NaX zeolite has both intercrystalline and intra-crystalline mesopores,smaller crystal size,and larger external specific surface area compared to commercial NaX zeolite.Detailed mechanism investigations show that the inter-crystalline mesopores are generated by stacking smaller crystals formed from in-situ crystallization of the depolymerized kaolinite,and the intra-crystalline mesopores are inherited from the pores in the depolymerized kaolinite.This synthesis strategy provides an energy-saving and effective way to construct hierarchical zeolites,which may gain wide applications in fine chemical manufacturing.

Optimal synthesis of heat-integrated distillation configurations using the two-column superstructure

In the realm of the synthesis of heat-integrated distillation configurations,the conventional approach for exploring more heat integration possibilities typically entails the splitting of a single column into a twocolumn configuration.However,this approach frequently necessitates tedious enumeration procedures,resulting in a considerable computational burden.To surmount this formidable challenge,the present study introduces an innovative remedy:The proposition of a superstructure that encompasses both single-column and multiple two-column configurations.Additionally,a simultaneous optimization algorithm is applied to optimize both the process parameters and heat integration structures of the twocolumn configurations.The effectiveness of this approach is demonstrated through a case study focusing on industrial organosilicon separation.The results underscore that the superstructure methodology not only substantially mitigates computational time compared to exhaustive enumeration but also furnishes solutions that exhibit comparable performance.

Microfluidic-oriented synthesis of enriched iridium nanodots/carbon architecture for robust electrocatalytic nitrogen fixation

Electrocatalytic nitrogen reduction reaction(NRR)is considered as a promising candidate to achieve ammonia synthesis because of clean electric energy,moderate reaction condition,safe operating process and harmless by-products.However,the chemical inertness of nitrogen and poor activated capacity on catalyst surface usually produce low ammonia yield and faradic efficiency.Herein,the microfluidic technology is proposed to efficiently fabricate enriched iridium nanodots/carbon architecture.Owing to in-situ co-precipitation reaction and microfluidic manipulation,the iridium nanodots/carbon nanomaterials possess small average size,uniform dispersion,high conductivity and abundant active sites,producing good proton activation and rapid electrons transmission and moderate adsorption/desorption capacity.As a result,the as-prepared iridium nanodots/carbon nanomaterials realize large ammonia yield of 28.73 μg h^(-1) cm^(-2) and faradic efficiency of 9.14%in KOH solution.Moreover,the high ammonia yield of 11.21 μg h^(-1) cm^(-2) and faradic efficiency of 24.30%are also achieved in H_(2)SO_(4) solution.The microfluidic method provides a reference for large-scale fabrication of nano-sized catalyst materials,which may accelerate the progress of electrocatalytic NRR in industrialization field.

Synthesis and Modulation of Low-Dimensional Transition Metal Chalcogenide Materials via Atomic Substitution

In recent years,low-dimensional transition metal chalcogenide(TMC)materials have garnered growing research attention due to their superior electronic,optical,and catalytic properties compared to their bulk counterparts.The controllable synthesis and manipulation of these materials are crucial for tailoring their properties and unlocking their full potential in various applications.In this context,the atomic substitution method has emerged as a favorable approach.It involves the replacement of specific atoms within TMC structures with other elements and possesses the capability to regulate the compositions finely,crystal structures,and inherent properties of the resulting materials.In this review,we present a comprehensive overview on various strategies of atomic substitution employed in the synthesis of zero-dimensional,one-dimensional and two-dimensional TMC materials.The effects of substituting elements,substitution ratios,and substitution positions on the structures and morphologies of resulting material are discussed.The enhanced electrocatalytic performance and photovoltaic properties of the obtained materials are also provided,emphasizing the role of atomic substitution in achieving these advancements.Finally,challenges and future prospects in the field of atomic substitution for fabricating low-dimensional TMC materials are summarized.

Boosting Fischer-Tropsch Synthesis via Tuning of N Dopants in TiO_(2)@CN-Supported Ru Catalysts

Nitrogen(N)-doped carbon materials as metal catalyst supports have attracted signifi cant attention,but the eff ect of N dopants on catalytic performance remains unclear,especially for complex reaction processes such as Fischer-Tropsch synthesis(FTS).Herein,we engineered ruthenium(Ru)FTS catalysts supported on N-doped carbon overlayers on TiO_(2)nanoparticles.By regulating the carbonization temperatures,we successfully controlled the types and contents of N dopants to identify their impacts on metal-support interactions(MSI).Our fi ndings revealed that N dopants establish a favorable surface environment for electron transfer from the support to the Ru species.Moreover,pyridinic N demonstrates the highest electron-donating ability,followed by pyrrolic N and graphitic N.In addition to realizing excellent catalytic stability,strengthening the interaction between Ru sites and N dopants increases the Ru^(0)/Ru^(δ+)ratios to enlarge the active site numbers and surface electron density of Ru species to enhance the strength of adsorbed CO.Consequently,it improves the catalyst’s overall performance,encompassing intrinsic and apparent activities,as well as its ability for carbon chain growth.Accordingly,the as-synthesized Ru/TiO_(2)@CN-700 catalyst with abundant pyridine N dopants exhibits a superhigh C_(5+)time yield of 219.4 mol CO/(mol Ru·h)and C_(5+)selectivity of 85.5%.

Recent advances in cobalt phosphide-based materials for electrocatalytic water splitting:From catalytic mechanism and synthesis method to optimization design

Electrochemical water splitting has long been considered an effective energy conversion technology for trans-ferring intermittent renewable electricity into hydrogen fuel,and the exploration of cost-effective and high-performance electrocatalysts is crucial in making electrolyzed water technology commercially viable.Cobalt phosphide(Co-P)has emerged as a catalyst of high potential owing to its high catalytic activity and durability in water splitting.This paper systematically reviews the latest advances in the development of Co-P-based materials for use in water splitting.The essential effects of P in enhancing the catalytic performance of the hydrogen evolution reaction and oxygen evolution reaction are first outlined.Then,versatile synthesis techniques for Co-P electrocatalysts are summarized,followed by advanced strategies to enhance the electrocatalytic performance of Co-P materials,including heteroatom doping,composite construction,integration with well-conductive sub-strates,and structure control from the viewpoint of experiment.Along with these optimization strategies,the understanding of the inherent mechanism of enhanced catalytic performance is also discussed.Finally,some existing challenges in the development of highly active and stable Co-P-based materials are clarified,and pro-spective directions for prompting the wide commercialization of water electrolysis technology are proposed.

Metagenomic analysis revealing the metabolic role of microbial communities in the free amino acid biosynthesis of Monascus rice vinegar during fermentation

Free amino acid(FAA)is the important component of vinegar that infl uences quality perception and consumer acceptance.FAA is one of the major metabolites produced by microorganisms;however,the microbial metabolic network on FAA biosynthesis remains unclear.Through metagenomic analysis,this work aimed to elucidate the roles of microbes in FAA biosynthesis during Monascus rice vinegar fermentation.Taxonomic profiles from functional analyses showed 14 dominant genera with high contributions to the metabolism pathways.The metabolic network for FAA biosynthesis was then constructed,and the microbial distribution in different metabolic pathways was illuminated.The results revealed that 5 functional genera were closely involved in FAA biosynthesis.This study illuminated the metabolic roles of microorganisms in FAA biosynthesis and provided crucial insights into the functional attributes of microbiota in vinegar fermentation.

Room Temperature Synthesis of Vertically Aligned Amorphous Ultrathin NiCo-LDH Nanosheets Bifunctional Flexible Supercapacitor Electrodes

Developing a simple scalable method to fabricate electrodes with high capacity and wide voltage range is desired for the real use of electrochemical supercapacitors.Herein,we synthesized amorphous NiCo-LDH nanosheets vertically aligned on activated carbon cloth substrate,which was in situ transformed from Co-metal-organic framework materials nano-columns by a simple ion exchange process at room temperature.Due to the amorphous and vertically aligned ultrathin structure of NiCo-LDH,the NiCo-LDH/activated carbon cloth composites present high areal capacities of 3770 and 1480 mF cm^(-2)as cathode and anode at 2 mA cm^(-2),and 79.5%and 80%capacity have been preserved at 50 mA cm^(-2).In the meantime,they all showed excellent cycling performance with negligible change after>10000 cycles.By fabricating them into an asymmetric supercapacitor,the device achieves high energy densities(5.61 mWh cm^(-2)and 0.352 mW cm^(-3)).This work provides an innovative strategy for simplifying the design of supercapacitors as well as providing a new understanding of improving the rate capabilities/cycling stability of NiCo-LDH materials.

Efficient electrocatalytic urea synthesis from CO_(2)and nitrate over the scale-up produced FeNi alloy-decorated nanoporous carbon

Electrocatalytic urea synthesis provides a favorable strategy for conventional energy-consuming urea synthesis,but achieving large-scale catalyst synthesis with high catalytic efficiency remains challenging.Herein,we developed a simple method for the preparation of a series of FeNi-alloy-based catalysts,named FeNi@nC-T(n represents the content of nanoporous carbon as 1,3,5,7 or 9 g and T=900,950,1000 or 1100°C),for highly performed urea synthesis via NO_(3)−and CO_(2)co-reduction.The FeNi@7C-1000 achieved a high urea yield of 1041.33 mmol h^(−1)gFeNi^(−1)with a Faradaic efficiency of 15.56%at–1.2 V vs.RHE.Moreover,the scale-up synthesized FeNi@7C-950-S(over 140 g per batch)was achieved with its high catalytic performance and high stability maintained.Mechanism investigation illuminated that the Ni and Fe sites catalyze and stabilize the key*CO and*N intermediates and minimize the C–N coupling reaction barriers for highly efficient urea synthesis.

Cost-Effective Method of Gene Synthesis by Sequencing from Microchip-Derived Oligos for Droplet Cloning

Gene synthesis has provided important contributions in various fields including genomics and medicine. Current genes are 7 - 30 cents depending on the assembly and sequencing methods performed. Demand for gene synthesis has been increasing for the past few decades, yet available methods remain expensive. A solution to this problem involves microchip-derived oligonucleotides (oligos), an oligo pool with a substantial number of oligo fragments. Microchips have been proposed as a tool for gene synthesis, but this approach has been criticized for its high error rate during sequencing. This study tests a possible cost-effective method for gene synthesis utilizing fragment assembly and golden gate assembly, which can be employed for quicker manufacturing and efficient execution of genes in the near future. The droplet method was tested in two trials to determine the viability of the method through the accuracy of the oligos sequenced. A preliminary research experiment was performed to determine the efficacy of oligo lengths ranging from two to four overlapping oligos through Gibson assembly. Of the three oligo lengths tested, only two fragment oligos were correctly sequenced. Two fragment oligos were used for the second experiment, which determined the efficacy of the droplet method in reducing gene synthesis cost and speed. The first trial utilized a high-fidelity polymerase and resulted in 3% correctly sequenced oligos, so the second trial utilized a non-high-fidelity polymerase, resulting in 8% correctly sequenced oligos. After calculating, the cost of gene synthesis lowers down to 0.8 cents/base. The final calculated cost of 0.8 cents/base is significantly cheaper than other manufacturing costs of 7 - 30 cents/base. Reducing the cost of gene synthesis provides new insight into the cost-effectiveness of present technologies and protocols and has the potential to benefit the fields of bioengineering and gene therapy.

Nucleosynthesis in the little bang

A new approach based on relativistic kinetic equations is proposed to solve the long-standing puzzle of light cluster formation, also called nucleosynthesis, in high-energy heavy-ion collisions. This method addresses the tension between STAR data and previous studies relying on either statistical equilibrium or coalescence approaches.

N,S,Br co-doped carbon dots:One-step synthesis and fluorescent detection of 6-mercaptopurine in tablet

6-mercaptopurine(6-MP),a purine derivative(3,7-dihydropurine-6-thione),has been utilized as an effective immunosuppressive drug for clinically treating leukemia and other autoimmune diseases[1].6-MP and its corresponding metabolites can suppress the function of RnaseH,and thus they are cytotoxic and threaten the human health[2].Therefore,the accurate quantification of 6-MP is crucial.To date,researchers continue to expend considerable effort in developing 6-MP detection methods.Fluorescence analysis eliminates disadvantages,such as toxic solvents,expensive equipment.

Synthesis Methods and Property Control of Two-Dimensional Magnetic Materials

Two-dimensional(2D)magnetic materials have been demonstrated to have excellent chemical,optical,electrical,and magnetic properties,particularly in the development of multifunctional electronic and spin electronic devices,showcasing tremendous potential.Therefore,corresponding synthesis techniques for 2D magnetic materials that offer high quality,high yield,low cost,time-saving,and simplicity are highly desired.This review provides a comprehensive overview of recent research advances in preparation of magnetic 2D materials,with a particular focus on the preparation methods employed.Moreover,the characteristics and applications of these magnetic materials are also discussed.Finally,the challenges and prospects of synthesis methods for magnetic 2D materials are briefly addressed.This review serves as a guiding reference for the controlled synthesis of 2D magnetic materials.

Synthesis of mordenite by solvent-free method and its application in the dimethyl ether carbonylation reaction

Mordenite with different Si/Al ratios were synthesized by solvent-free method and used for dimethyl ether(DME)carbonylation reaction.The influence of Si/Al ratio in the feedstock on the structure,porosity and acid sites were systematically investigated.The characterization results showed that with the increase of Si/Al ratio in the feedstock,part of silicon species fail to enter the skeleton and the specific surface area and pore volume of the samples decreased.The amount of weak acid and medium strong acid decreased alongside with the increasing Si/Al ratio,and the amount of strong acid slightly increased.The Al atoms preferentially enter the strong acid sites in the 8 member ring(MR)channel during the crystallization process.The high Si/Al ratio sample had more acid sites located in the 8 MR channel,leading to more active sites for carbonylation reaction and higher catalytic performance.Appropriately increasing the Si/Al ratio was beneficial for the improvement of carbonylation reaction activity over the mordenite(MOR)catalyst.

Synthesis of Silver Nanoparticles from Honeybees and Its Antibacterial Potential

Honeybees (Apis mellifera) are important pollinators of flowering plants and agricultural crops contributing annually to billions of dollars in revenues to crop production. Honeybees have an average lifespan between 8 weeks to 5 years. Dead honeybees are abundantly available in beehives and can be utilized as an alternative source to synthesize nanoparticles. In recent years, biologically synthesized nanoparticles have been preferred over their chemical counterparts. However, honeybee-based-green synthesis of nanoparticles has not been explored yet. Herein, we report the biosynthesis of silver nanoparticles from honeybees and its antibacterial activity. The synthesis of silver nanoparticles was monitored visually through a gradual change in color. Furthermore, the biosynthesized nanoparticles were confirmed and characterized by UV-visible spectroscopy. Scanning Electron Microscope was utilized to analyze the average size and morphologies of the biosynthesized nanoparticles. Subsequently, the antibacterial potential of the biosynthesized silver nanoparticles was tested against selected Gram-positive and Gram-negative bacterial strains. It was found that a distinct color change from yellow to brown in the reaction solution suggested the formation of silver nanoparticles. The biosynthesized nanoparticles exhibited absorption maxima at 430 nm. The SEM analysis confirmed the spherical and cuboidal shape of the biosynthesized silver nanoparticles with a size range between 10 - 40 nm. Furthermore, the biosynthesized silver nanoparticles exhibited strong antimicrobial potential against tested Gram-positive and Gram-negative bacteria strains by aggregating on the cell surface. This study showcases the biomedical and agricultural applications of biosynthesized silver nanoparticles from honeybee wings. .