A Perspective on the Evolution of Atmospheric Blocking Theories:From Eddy-Mean flow Interaction to Nonlinear Multiscale Interaction

In this paper,we first review the research advancements in blocking dynamics and highlight the merits and drawbacks of the previous theories of atmospheric blocking.Then,the dynamical mechanisms of atmospheric blocking are presented based on a nonlinear multi-scale interaction(NMI)model.Previous studies suggested that the eddy deformation(e.g.,eddy straining,wave breaking,and eddy merging)might lead to the formation and maintenance of atmospheric blocking.However,the results were speculative and problematic because the previous studies,based on the time-mean eddy-mean flow interaction model,cannot identify the causal relationship between the evolution of atmospheric blocking and the eddy deformation.Based on the NMI model,we indicate that the onset,growth,maintenance,and decay of atmospheric blocking is mainly produced by the spatiotemporal evolution of pre-existing upstream synoptic-scale eddies,whereas the eddy deformation is a concomitant phenomenon of the blocking formation.The lifetime of blocking is mainly determined by the meridional background potential vorticity gradient(PVy)because a small PVyfavors weak energy dispersion and strong nonlinearity to sustain the blocking.But the zonal movement of atmospheric blocking is associated with the background westerly wind,PVy,and the blocking amplitude.Using this NMI model,a bridge from the climate change to sub-seasonal atmospheric blocking and weather extremes might be established via examining the effect of climate change on PVy.Thus,it is expected that using the NMI model to explore the dynamics of atmospheric blocking and its change is a new direction in the future.

Seasonal Cumulative Effect of Ural Blocking Episodes on the Frequent Cold events in China during the Early Winter of 2020/21

Starting in mid-November,China was hit by several cold events during the early winter of 2020/21.The lowest temperature observed at Beijing station on 7 January reached−19.6°C.In this paper,we show that the outbreak of the record-breaking extreme cold event can be attributed to a huge merging Ural blocking(UB)ridge over the Eurasian region.The sea-ice cover in the Kara and East Siberia Seas(KESS)in autumn was at its lowest value since 1979,which could have served as a precursor signal.Further analysis shows that several successive UB episodes occurred from 1 September 2020 to 10 January 2021.The persistent UB that occurred in late September/early October 2020 may have made an important contribution to the October historical minimum of sea ice in the KESS region.Our results also show that,after each UB episode in winter,significant upward propagation of wave activity occurred around 60°E,which resulted in weakening the stratospheric vortex.Meanwhile,each UB episode also caused a significant reduction in sea-ice extent in KESS and a significant weakening of the westerly jet in mid-high-latitude Eurasia.Results suggest that the Arctic vortex,which is supposed to enhance seasonally,became weaker and more unstable than the climatic mean under the seasonal cumulative effects of UB episodes,KESS warming,and long-lasting negative-phase North Atlantic Oscillation(NAO-).Those seasonal cumulative effects,combined with the impact of La Niña winter,led to the frequent occurrence of extreme cold events.

Measurement of dynamic resistance in resistance spot welding

The conventional methods of determining the dynamic resistance were mostly done by measuring the voltage and current at secondary side of transformer in resistance welding machines, in which the measuring set-up normally interferes with the movement of electrode, and the measuring precision is influenced by inductive noise caused by the high welding current. In this study, the dynamic resistance is determined by measuring the voltage at primary side and current at secondary side. This increases the accuracy of measurement because of higher signal-noise ratio, and allows to apply to in-process system without any wires connected to electrodes.

Reuse of Ferric Sludge by Ferrous Sulfide in the Fenton Process for Nonylphenol Ethoxylates Wastewater Treatment

In this paper, Fenton process was determined to be an effective technique to treat the refractory Nonylphenol ethoxylates (NPEOs) wastewater. The COD removal efficien-cies above 89% were obtained when the initial COD concentration was 12000mg/L. However, A large number of ferric sludge (SS=8.724g/L) would be produced after the Fenton oxidation of the wastewater and must be disposed appropriately. A novel process for Fenton sludge reused by low-cost ferrous sulfide (FeS) was also investi-gated. Experimental results show that the Fenton sludge could be reduced to produce a certain amount of Fe2+ in the acidic mixed liquor by ferrous sulfide. This mixed liquor from Fenton sludge could be used as the new catalyst in the Fenton process and was also highly effective for the NPEOs wastewater treatment. The residual ferrous sulfide from the mixed liquor could be used for the next batch of the

Treatment of the High Concentration Nonylphenol Ethoxylates (NPEOs) Wastewater by Fenton Oxidation Process

The Fenton oxidation process was applied in the treatment of an actual high concentration nonylphenol Ethoxylates (NPEOs) wastewater. The effects of H2O2 dosage, molar ratio of H2O2/Fe2+ (Fe2+ dosage), pH value and reaction time on the degradation of NPEOs were investigated. The orthogonal experiment indicated that the order of degree of influence on the COD removal was molar ratio of H2O2/Fe2+, reaction time, dosage of H2O2, and initial pH. The single-factor tests were carried out to determine the optimal conditions, and the results were H2O2 dosage of 76.32 mmol/L, molar ratio of H2O2/Fe2+ of 3, pH value of 5 and reaction time of 2 h. Under the optimum operation conditions, the COD removal efficiency was 85.6% and the effluent could be mixed with other wastewater into the large-scale biological treatment system.

Carbonization of Chlorinated Organic Residual Liquid for Energy Source Generation

Chlorinated organic residual liquid is produced from the distillation process of new refrigerants production. It is difficult to be treated by traditional water treatment process and incineration process. In this study, a carbonization process at atmospheric pressure was used to convert this residual liquid to carbonaceous product and organic gas in 2 h at 230℃ or 260℃. The carbonaceous product was characterized by scanning electron microscope, Fourier-transform infrared spectrometer and thermo gravimetric analysis. The element composition and the high heat value of these products were similar to anthracite and lignite, respectively, showing that they could be used as alternative fuels. The components of organic gas were analyzed using gas chromatography-mass spectrometry and the gas had potential for incineration.

Hydrothermal Carbonization of Nonylphenol Ethoxylates Waste Liquid for Energy Source Generation

Nonylphenol polyethoxylates (NPEOs) are widely used as nonionic surfactants in many industry fields. High concentration NPEOs waste water is produced in some production processes. It is often treated to realize reduction by distillation. Therefore, NPEOs waste liquid with higher concentration is produced and it is difficult to be treated by traditional water treatment process. In this study, hydrothermal carbonization process was used to convert NPEOs waste liquid to carbonaceous product (hydrochar) with sulfuric acid as additive in 24 h at 200°C. The hydrochar was characterized by scanning electron microscope, Fourier-transform infrared spectrometer and thermogravimetric analysis. The element composition and the high heat value of the hydrochar were similar to lignite, showing that it could be used as an alternative fuel.

Clinical Significance of METTL Family Molecules in Hepatocellular Carcinoma

Objective:to search for hepatocellular carcinoma(HCC)in tumor subdivision from different aspects,such as transcripts,proteins,gene mutations,protein interactions,signal pathways and functions.To explore the correlation between METTL1-6 protein family and hepatocellular carcinoma(HCC),and to determine whether METTL family proteins are valuable as potential biomarkers for tumor progression and prognosis of HCC.Methods:We try to use data collection technique to extract the data needed in medical analysis.The correlation between the MRNA expression level of METTL family proteins and the prognosis of HCC patients was obtained from TCGA data.METTL data and clinical data of protein METTL family in tissue samples of HCC patients were obtained from Kaplan-Meier Plotter database for correlation analysis.The immunohistochemical data of METTL family protein 1,2A,2B,3,4,5,6 in normal liver tissue and HCC tissue were obtained from TIMER database.The protein network of METTL proteome was obtained by using STRING database,and the heat map enrichment analysis of proteome interaction between KEGG and GO was done by software.Results:6 of the 7 METTL protein members were highly expressed in HCC tissues,and were positively correlated with the grade and clinical analysis of HCC tumors.

Evaluation of bacterial contamination on three different surfaces within domestic refrigerators

The objectives of this study were to analyze the number of microorganisms,fungal composition and the correlation between bacterial enrichment and air quality on three internal surfaces(the inner wall,shelf,and basket)of domestic refrigerators.The results showed that the inner wall had a significantly lower number of coliforms(P<0.05),and the range was 0.2−2.5 log MPN cm^(-2).The total bacterial counts and psychrophilic bacterial counts on three internal surfaces in the same refrigerator tended to be consistent.Moreover,the inner wall owned a simpler bacterial community structure.At the genus level of fungi,the dominant flora of both the inner wall and shelf were Saccharomyces spp.and Candida spp.,while Saccharomyces spp.,Candida spp.and Fistulina spp.took superiority in the basket.Specifically,Shannon index and Simpson index,which represent the bacterial community diversity,were the lowest on the wall,and six bacterial species on the inner wall had relative abundance higher than 0.5%of the total operational taxonomic units(OTUs),while for the shelf and basket,there were 12 and 11 bacterial species respectively.Also,there was a significant negative correlation in the basket between the chao1 index and PM2.5.This study could provide guidance for the sanitation and recommend adequate packaging of foods stored in refrigerators.

The interaction mechanism between zein and folic acid in alkaline aqueous solutions:an experimental and molecular simulation study

Objectives:Folic acid is a vitamin that is not highly soluble in water and is sensitive to the environment.Therefore,it is important to find suitable carriers.This study aimed to exemplify the interaction of folic acid with zein in alkaline aqueous solutions and shed light on how zein can be used as a carrier for folic acid.Materials and Methods:Zein and folic acid were separately dissolved in NaOH solutions with a PH of 11.5.Zein solution and folic acid solution were combined in specific ratios.Various methods including multi-spectroscopy,dynamic light scattering,and electron microscopy combining with molecular dynamics simulations were used to study the interaction mechanism between zein and folic acid in alkaline aqueous solutions.Results:Fluorescence spectroscopy showed that the quenching of zein by folic acid was mainly static,and the main driving force behind this interaction was van der Waals forces and hydrogen bonds.The formation of zein–folic acid complexes was confirmed by ultraviolet–visible spectroscopy,Fourier transform infrared spectroscopy,and circular dichroism spectroscopy.The results also showed that the structure of zein changed when it interacted with folic acid.Dynamic light scattering analysis revealed that the addition of folic acid caused proteins to aggregate.The aggregates of the complexes had an irregular shape and were large,as observed by scanning electron microscopy and transmission electron microscopy.Molecular simulation was used to further investigate the interaction mechanisms.According to these findings,the folic acid molecule interacted with zein in a shallow recess near the protein surface.The dominant forces at play in the zein–folic acid interaction were van der Waals forces and electrostatic forces,including hydrogen bonding.Conclusion:The zein alkali-soluble system is very suitable for folic acid delivery.

In situ atomic-scale observation of size-dependent (de) potassiation and reversible phase transformation in tetragonal FeSe anodes

Potassium-ion batteries(PIBs)are considered promising alternatives to lithium-ion batteries owing to cost-effective potassium resources and a suitable redox potential of-2.93 V(vs.-3.04 V for Li+/Li).However,the exploration of appro-priate electrode materials with the correct size for reversibly accommodating large K+ions presents a significant challenge.In addition,the reaction mecha-nisms and origins of enhanced performance remain elusive.Here,tetragonal FeSe nanoflakes of different sizes are designed to serve as an anode for PIBs,and their live and atomic-scale potassiation/depotassiation mechanisms are revealed for the first time through in situ high-resolution transmission electron micros-copy.We found that FeSe undergoes two distinct structural evolutions,sequen-tially characterized by intercalation and conversion reactions,and the initial intercalation behavior is size-dependent.Apparent expansion induced by the intercalation of K+ions is observed in small-sized FeSe nanoflakes,whereas unexpected cracks are formed along the direction of ionic diffusion in large-sized nanoflakes.The significant stress generation and crack extension originating from the combined effect of mechanical and electrochemical interactions are elucidated by geometric phase analysis and finite-element analysis.Despite the different intercalation behaviors,the formed products of Fe and K_(2)Se after full potassiation can be converted back into the original FeSe phase upon depotassiation.In particular,small-sized nanoflakes exhibit better cycling perfor-mance with well-maintained structural integrity.This article presents the first successful demonstration of atomic-scale visualization that can reveal size-dependent potassiation dynamics.Moreover,it provides valuable guidelines for optimizing the dimensions of electrode materials for advanced PIBs.

Mapping soil organic matter content using Sentinel-2 syntheticimages at different time intervals in Northeast China

Mapping soil organic matter(SOM)content has become an important application of digital soil mapping.In this study,we processed all Sentinel-2 images covering the bare-soil period(March to June)in Northeast China from 2019 to 2022 and integrated the observation results into synthetic materials with four defined time intervals(10,15,20,and 30 d).Then,we used synthetic images corresponding to different time periods to conduct SOM mapping and determine the optimal time interval and time period beforefinally assessing the impacts of adding environmental covariates.The results showed the following:(1)in SOM mapping,the highest accuracy was obtained using day-of-year(DOY)120 to 140 synthetic images with 20 d time intervals,as well as with different time intervals,ranked as follows:20 d>30 d>15 d>10 d;(2)when using synthetic images at different time intervals to predict SOM,the best time period for predicting SOM was always within May;and(3)adding environmental covariates effectively improved the SOM mapping performance,and the multiyear average temperature was the most important factor.In general,our results demonstrated the valuable potential of SOM mapping using multiyear synthetic imagery,thereby allowing detailed mapping of large areas of cultivated soil.

大气硝酸盐中氧同位素异常研究进展

硝酸盐是大气中的主要污染物,其前体物NO_x(NO+NO_2)参与大气中多种光化学反应,可以改变大气氧化特性,有利于细颗粒物的形成,影响气候系统与人类健康.硝酸盐氧同位素异常(Δ^(17)NO_3^-)是解析大气硝酸盐生成途径的有力手段.本文对大气硝酸盐氧同位素异常的研究进展进行了综述.首先列举了测试大气硝酸盐三氧同位素(^(16)O, ^(17)O和^(18)O)的前处理方法(热解法、细菌法和化学法),并对比了全球范围内大气硝酸盐氧同位素异常的时空分布特征.其次总结了大气中硝酸盐生成的主要途径及其氧同位素质量守恒,讨论了大气硝酸盐中氧原子的可能来源及其氧同位素异常值,评估了全球及典型区域尺度上氧同位素异常的模型.最后对大气硝酸盐氧同位素异常的未来研究方向进行了展望.

员工需要为在职培训买单吗?——来自职工教育经费税前扣除改革的经验证据

人力资本模型是企业培训行为的背后逻辑,对其进行研究具有重要的理论意义和现实价值。不同于已有文献从最低工资标准对培训的影响这一间接角度切入,文章利用高新技术企业职工教育经费税前扣除比例改革(财税[2015]63号)这一外生冲击,以2012-2017年中国沪深A股上市公司为样本,检验政策引起的在职培训增加对员工当期工资的直接影响。研究发现,在职培训的增加伴随着员工当期工资增长的显著减缓,即员工需要为在职培训买单。进一步按照企业所在地区最低工资标准、内部工会实质性作用以及企业所需技能的特殊性,将样本分为工资结构压缩程度高低两组进行分组检验发现,培训增加导致的员工当期工资减少主要发生在工资结构压缩程度较低的企业中。文章为不完全竞争市场人力资本模型提供了直接的经验证据,对企业在职培训决策具有参考价值。

Preparation of cross-linked magnetic chitosan with quaternary ammonium and its application for Cr(Ⅵ) and P(Ⅴ) removal

Pollutants that exist in anionic species are issues of concern in water treatment. Compared to cationic pollutants, the removal of anionic pollutants by adsorption is more difficult because most adsorbents carry predominantly negative charges in neutral and alkaline environments. In this study, a cross-linked chitosan derivative with quaternary ammonium and magnetic properties（QM-chitosan） was prepared and employed to remove chromium（VI） and phosphorus（V）（Cr（VI） and P（V）） from aqueous environments. The QM-chitosan was characterized by Fourier transform infrared spectrometry（FT-IR）,thermogravimetric analysis（TGA）, energy dispersive X-ray（SEM-EDX） and zeta potential.Batch experiments show that QM-chitosan can effectively remove Cr（VI） and P（V）, and the main mechanism was believed to be electrostatic interaction. A pseudosecond-order model was fitted to describe the kinetic processes of Cr（VI） and P（V） removal. The adsorption isotherms of both Cr（VI） and P（V） on the QM-chitosan were well fitted by the Langmuir isotherm equation. The saturated adsorption capacity of P（V）（2.783 mmol/g） was found to be higher than that of Cr（VI）（2.323 mmol/g）, resulting from the size of the H2PO-4ions being smaller than that of the HCr O-4ions. However, the theoretical calculation and experimental results showed that QM-chitosan had a stronger affinity for Cr（VI） than P（V）. The adsorption–desorption of the QM-chitosan was evaluated, and high regeneration rates were demonstrated.

Interfacial characteristics and mechanical properties of additive manufacturing martensite stainless steel on the Cu-Cr alloy substrate by directed energy deposition

Copper/steel is a typical bimetal functional material,combining the excellent electrical and thermal conductivity of copper alloy and the high strength and hardness of stainless steel.There has been recent interest in manufacturing copper/steel bimetal by directed energy deposition(DED)due to its layer-bylayer method.However,cracks tend to form on the copper/steel interface because of the great difference in thermal expansion coefficient and crystal structure between copper and steel.In this work,interfacial characteristics and mechanical properties of the copper/steel bimetal were studied from one layer to multilayers.The laser power has a great influence on the Cu element distribution of the molten pool,affecting the crack formation dramatically on the solidification stage.Cracks tend to form along columnar grain boundaries because of the Cu-rich liquid films and spherical particles in the cracks.Crack-free and good metallurgical bonding copper/steel interface is formed at a scanning velocity of 800 mm/min and the laser power of 3000 W.The ultimate tensile strength(UTS)and the break elongation(EL)of the vertically combined crack-free copper/steel bimetal are 238.2±4.4 MPa and 20.6±0.7%,respectively.The fracture occurs on the copper side instead of the copper/steel interface,indicating that the bonding strength is higher than that of the Cu-Cr alloy.The UTS of the horizontally combined crack-free copper/steel bimetal is 746.7±22.6 MPa,which is 200%higher than that of the Cu-Cr alloy substrate.The microhardness is 398.6±5.4 HV at the steel side and is 235.3±64.1 HV at the interface,which is400%higher than that of the Cu-Cr alloy substrate.This paper advances the understanding of the interfacial characteristics of heterogeneous materials and provides guidance and reference for the fabrication of multi-material components by DED.

Identification of micro RNAs in six solanaceous plants and their potential link with phosphate and mycorrhizal signalings

To date, only a limited number of solanaceous miRNAs have been deposited in the miRNA database. Here,Rgenome-wide bioinformatic identification of miRNAs was performed in six solanaceous plants（potato, tomato, tobacco,eggplant, pepper, and petunia）. A total of 2,239 miRNAs were identified following a range of criteria, of which 982 were from potato, 496 from tomato, 655 from tobacco, 46 from eggplant,45 were from pepper, and 15 from petunia. The sizes of miRNA families and miRNA precursor length differ in all the species.Accordingly, 620 targets were predicted, which could be functionally classified as transcription factors, metabolic enzymes, RNA and protein processing proteins, and other proteins for plant growth and development. We also showed evidence for miRNA clusters and sense and antisense miR NAs.Additionally, five Pi starvation- and one arbuscular mycorrhiza（AM）-related cis-elements were found widely distributed in the putative promoter regions of the miRNA genes. Selected miRNAs were classified into three groups based on the presence or absence of P1BS and MYCScis-elements, and their expression in response to Pi starvation and AM symbiosis was validated by quantitative reverse transcription-polymerase chain reaction（qRT-PCR）. These results show that conserved miRNAs exist in solanaceous species and they might play pivotal roles in plant growth, development, and stress responses.

Optical absorption via intersubband transition of electrons in GaAs/Al_xGa_(1-x)As multi-quantum wells in an electric field

Based on the effective mass approximation, the Schrodinger equation and Poisson equation in GaAs/AlGaAs multi-quantum wells(MQWs) are self-consistently solved to obtain the wave functions and energy levels of electrons in the conduction band for the ground first excited state by considering a lateral electric field(LEF). Then, the effects of size, ternary mixed crystal, doping concentration, and temperature on linear and nonlinear intersubband optical absorption coefficients(IOACs), and refractive index changes(RICs) due to the transition between ground states and the first excited states of electrons are discussed based on Fermi’s golden rule. The results show that, under a fixed LEF, with increase of A1 composition and doping concentration, the IOACs produce a red shift. With increases of both widths of the wells and barriers IOACs appear as blue shifts and their amplitudes increase, but the barrier width change is much more important to affect nonlinear IOACs, whereas increasing the temperature results in a blue shift first and then a red shift of IOACs. When the other parameters are fixed but there is an increase in the LEF, IOACs occur with a blue shift, and the RICs have similar properties.