Optical manipulation of the topological phase in ZrTe_(5) revealed by time-and angle-resolved photoemission

High-resolution time-and angle-resolved photoemission measurements were conducted on the topological insulator ZrTe_(5).With strong femtosecond photoexcitation,a possible ultrafast phase transition from a weak to a strong topological insulating phase was experimentally realized by recovering the energy gap inversion in a time scale that was shorter than 0.15 ps.This photoinduced transient strong topological phase can last longer than 2 ps at the highest excitation fluence studied,and it cannot be attributed to the photoinduced heating of electrons or modification of the conduction band filling.Additionally,the measured unoccupied electronic states are consistent with the first-principles calculation based on experimental crystal lattice constants,which favor a strong topological insulating phase.These findings provide new insights into the longstanding controversy about the strong and weak topological properties in ZrTe_(5),and they suggest that many-body effects including electron–electron interactions must be taken into account to understand the equilibrium weak topological insulating phase in ZrTe_(5).

Combined QTL mapping,GWAS and transcriptomic analysis revealed a candidate gene associated with the timing of spring bud flush in tea plant(Camellia sinensis)

Dear Editor,The timing of the spring bud f lush(TBF)is a crucial agro-nomic trait for the tea plant,as it strongly influences the yield and economic value of harvested fresh tea leaves.The TBF of tea plant is generally defined as the date when>30%of the growing tender shoots have reached the stage of one bud with one to three leaves,referred as to the stage of one and a bud,two and a bud,and three and a bud,respectively.

基于铜死亡相关基因构建肺腺癌预后模型和药物敏感性分析

背景与目的肺癌是全球最常见的恶性肿瘤之一,目前肺癌筛查和治疗策略不断完善,但其5年生存率仍然很低,严重危害人类的健康。因此探索新的生物标志物,提供个体化治疗并改善患者预后至关重要。铜死亡是一种新发现的细胞死亡类型,是由于细胞内过量铜离子积累,最终导致细胞死亡,已有研究提示其与肺腺癌(lung adenocarcinoma,LUAD)的发生发展密切相关。本研究基于肿瘤基因组图谱(The Cancer Genome Atlas,TCGA)数据库,探究铜死亡相关基因(cuproptosis related gene,CRGs)与LUAD预后之间的关联,建立预后风险模型并分析CRGs与LUAD免疫细胞浸润之间的相互作用,为肺腺癌患者的治疗及预后提供参考。方法从TCGA数据库中下载LUAD组织和癌旁或正常肺组织的RNA-seq数据,从基因型-组织表达资料库(Genotype-tissue Expression,GTEx)下载正常肺组织的RNA-seq数据,并从基因表达综合数据库(Gene Expression Omnibus,GEO)下载462例肺腺癌数据作为验证,采用单因素Cox和Lasso-Cox回归分析构建评估预后的风险评分模型,用受试者工作特征(receiver operating characteristic,ROC)曲线及校准曲线评价模型的预测能力。并进一步对高、低风险组进行免疫相关和药物敏感性分析。结果共得到1656个CRGs,其中有1356个存在差异表达的CRGs,基于单因素Cox和Lasso-Cox回归分析筛选出13个CRGs构建预后风险模型,ROC曲线1、3、5年的曲线下面积(area under the curve,AUC)分别为0.749、0.740、0.689。进一步研究高、低风险组之间免疫相关功能和免疫检查点差异分析。高风险组对萨沃替尼、帕博西尼、阿糖胞苷等药物敏感性更高,更容易从免疫治疗中获益。结论基于13个CRGs构建的风险模型具有较好的预后价值,可以辅助LUAD患者进行个体化治疗,为LUAD的治疗及预后研究提供了重要理论依据。

新型超稳定四氢喹啉连接的共价有机骨架材料的制备及其不对称光催化性能

不对称光催化有机合成是一种可持续的、环境友好的以太阳光为能源生产光学活性化学品的方法.绝大多数不对称光催化有机合成体系是由有机染料或无机半导体作为捕光材料与手性催化剂耦合构成.然而通常面临有机染料吸收谱带窄、光腐蚀严重,以及无机半导体材料的能带结构和带隙难以调控等问题.直到目前,仍然缺乏具有可调节带隙结构和高循环稳定性的半导体材料.最近,一类通过共价键连接形成、具有晶态有序结构的共价有机骨架材料(COFs)被报道用于光催化有机合成.但多数COFs材料均由可逆的化学键(如B-O-B键、-C=N键等)构成,其化学稳定性和光稳定性有待提升.目前已报道的一些稳定COFs均基于特殊的单体结构或通过后修饰策略制备,其合成路线过长并需要对单体进行额外的修饰.本文中,我们发展了一种具有普适性的通过不可逆四氢喹啉连接的COFs材料的制备方法,并考察了该材料在不对称光催化反应中的活性和稳定性.我们以1,3,5-三(4’-醛基苯基)苯、1,3,5-三(4’-氨基苯基)苯(或联苯胺)和乙烯基乙醚为原料,以三氟甲磺酸钪和三氟甲磺酸镱为催化剂,通过一锅法波瓦罗夫反应制备了两种以不可逆四氢喹啉连接的新型共价有机骨架材料QH-COFs.QH-COFs材料表现出了极高的化学稳定性,在浓硫酸、浓盐酸、三氟乙酸或氢氧化钠溶液中浸泡三天,其比表面积和结晶性均没有发生明显变化.QH-COFs(作为半导体)和手性二级胺(为手性催化剂)在可见光下可高效催化醛的不对称α烷基化反应,ee值高达94%.由于QH-COFs具有窄的禁带宽度和适合的能带结构,在相同条件下,QH-COFs的活性明显优于无机半导体(如二氧化钛、钒酸铋、三氧化钨等).QH-COFs是迄今为止报道的在可见光下催化醛的不对称α烷基化反应活性最高的半导体材料.由于四氢喹啉结构的存在,QH-COFs具有极高的循环稳定性,在循环五次之后,活性和ee值没有发生明显下降,并且其仍保持高结晶性.理论上所有可构筑亚胺COFs的单体均可通过该策略制备出稳定四氢喹啉结构的COFs材料,且无需对单体作任何修饰.该工作不仅为不对称光催化开辟了一条新途径,同时也为构筑稳定的COFs材料提供了一种高效、普适性方法.

Regulation of fruit ripening by the brassinosteroid biosynthetic gene SlCYP90B3 via an ethylenedependent pathway in tomato

The essential role of ethylene in fruit ripening has been thoroughly studied.However,the involvement of brassinosteroids(BRs)in the regulation of fruit ripening and their relationship with the ethylene pathway are poorly understood.In the current study,we found that BRs were actively synthesized during tomato fruit ripening.We then generated transgenic lines overexpressing or silencing SlCYP90B3,which encodes a cytochrome P450 monooxygenase that catalyzes the rate-limiting step of BR synthesis.The expression level of SlCYP90B3 was positively related to the contents of bioactive BRs as well as the ripening process in tomato fruit,including enhanced softening and increased soluble sugar and flavor volatile contents.Both carotenoid accumulation and ethylene production were strongly correlated with the expression level of SlCYP90B3,corroborated by the altered expression of carotenoid biosynthetic genes as well as ethylene pathway genes in transgenic tomato fruits.However,the application of the ethylene perception inhibitor 1-methycyclopropene(1-MCP)abolished the promotion effect of SlCYP90B3 overexpression on carotenoid accumulation.Taken together,these results increase our understanding of the involvement of SlCYP90B3 in bioactive BR biosynthesis as well as fruit ripening in tomato,thus making SlCYP90B3 a target gene for improvement of visual,nutritional and flavor qualities of tomato fruits with no yield penalty.

Ground-Based Hyperspectral Stereoscopic Remote Sensing Network: A Promising Strategy to Learn Coordinated Control of O_(3) and PM_(2.5) over China

With the coming of the“14th Five-Year Plan,”the coordinated control of particulate matter with an aerodynamic diameter no greater than 2.5 lm(PM_(2.5))and O_(3) has become a major issue of air pollution prevention and control in China.The stereoscopic monitoring of regional PM_(2.5) and O_(3) and their precursors is crucial to achieve coordinated control.However,current monitoring networks are currently inadequate for monitoring the vertical profiles of both PM_(2.5) and O_(3) simultaneously and support air quality control.The University of Science and Technology of China(USTC)has established a nationwide ground-based hyperspectral stereoscopic remote sensing network based on multi-axis differential optical absorption spectroscopy(MAX-DOAS)since 2015.This monitoring network provides a significant opportunity for the regional coordinated control of PM_(2.5) and O_(3) in China.One-year vertical profiles of aerosol,NO_(2) and HCHO monitored from four MAX-DOAS stations installed in four megacities(Beijing,Shanghai,Shenzhen,and Chongqing)were used to characterize their vertical distribution differences in four key regions,Jing–Jin–Ji(JJJ),Yangtze River Delta(YRD),Pearl River Delta(PRD),and Sichuan Basin(SB),respectively.The normalized and yearly averaged aerosol vertical profiles below 400 m in JJJ and PRD exhibit a box shape and a Gaussian shape,respectively,and both show exponential shapes in YRD and SB.The NO_(2) vertical profiles in four regions all exhibit exponential shapes because of vehicle emissions.The shape of the HCHO vertical profile in JJJ and PRD was Gaussian,whereas an exponential shape was shown in YRD and SB.Moreover,a regional transport event occurred at an altitude of 600–1000 m was monitored in the southwest–northeast pathway of the North China Plain(NCP)by five MAX-DOAS stations(Shijiazhuang(SJZ),Wangdu(WD),Nancheng(NC),Chinese Academy of Meteorological Sciences(CAMS),and University of Chinese Academy of Sciences(UCAS))belonging to the above network.The aerosol optical depths(AOD)in these five stations decreased in the order of SJZ>WD>NC>CAMS>UCAS.The short-distance regional transport of NO2 in the 700–900 m layer was monitored between WD and NC.As an important precursor of secondary aerosol,the peak of NO_(2) air mass in WD and NC all occurred 1 h earlier than that of aerosol.This was also observed for the short-distance regional transport of HCHO in the 700–900 m layer between NC and CAMS,which potentially affected the O_(3) concentration in Beijing.Finally,CAMS was selected as a typical site to determine the O_(3)–NO_(x)–volatile organic compounds(VOCs)sensitivities in vertical space.We found the production of O_(3) changed from predominantly VOCs-limited conditions to mainly mixed VOCs–NO_(x)-limited condition from the 0–100 m layer to the 200–300 m layer.In addition,the downward transport of O_(3) could contribute to the increase of ground surface O_(3) concentration.This ground-based hyperspectral stereoscopic remote sensing network provide a promising strategy to support management of PM_(2.5) and O_(3) and their precursors and conduct attribution of sources.

Simulation of incompressible multiphase flows with complex geometry using etching multiblock method

The incompressible two-phase flows are simulated using combination of an etching multiblock method and a diffuse interface(DI) model, particularly in the complex domain that can be decomposed into multiple rectangular subdomains. The etching multiblock method allows natural communications between the connected subdomains and the efficient parallel computation. The DI model can consider two-phase flows with a large density ratio, and simulate the flows with the moving contact line(MCL) when a geometric formulation of the MCL model is included. Therefore, combination of the etching method and the DI model has potential to deal with a variety of two-phase flows in industrial applications. The performance is examined through a series of numerical experiments. The convergence of the etching method is firstly tested by simulating single-phase flows past a square cylinder, and the method for the multiphase flow simulation is validated by investing drops dripping from a pore. The numerical results are compared with either those from other researchers or experimental data. Good agreement is achieved.The method is also used to investigate the impact of a droplet on a grooved substrate and droplet generation in flow focusing devices.

MAX-DOAS and in-situ measurements of aerosols and trace gases over Dongying,China:Insight into ozone formation sensitivity based on secondary HCHO

This study presents a comprehensive overview of the atmospheric pollutants including Sulfur dioxide(SO_(2)),Nitrogen dioxide(NO_(2)),Formaldehyde(HCHO),Particulate Matter PM;PM_(10):diameter≤10μm,and PM_(2.5):diameter≤2.5μm,and Ozone(O_(3)),over Dongying(Shandong Province)from March-April 2018 and September-October 2019 by employing ground-based Multiple Axis Differential Optical Absorption Spectroscopy(MAX-DOAS)observations along with the in-situ measurements attained by the national air quality monitoring platform.The concentrations of SO_(2)and NO_(2)were under the acceptable level,while both PM_(2.5),and PM_(10)were higher than the safe levels as prescribed by national and international air quality standards.The results depict that 21%of the total observation days were found to be complex polluted days(PM_(2.5)>35μg/m^(3) and O_(3)>160μg/m^(3)).The secondary HCHO was used for accurate analysis of O_(3)sensitivity.A difference of 11.40%and 10%during March-April 2018 and September-October 2019 respectively in O_(3)sensitivity was found between HCHO_(total)/NO_(2)and HCHO_(sec)/NO_(2).The results indicate that primary HCHO have significant contribution in HCHO.O_(3)formation predominantly remained to be in VOC-limited and transitional regime during March-April 2018 and September-October 2019 in Dongying.These results imply that concurrent control of both NO_(x) and VOCs would benefit in ozone reductions.Additionally,the criteria pollutants(PM,SO_(2),and NO_(2))depicted strong correlations with each other except for O_(3)for which weak correlation coefficient was obtained with all the species.This study will prove to be baseline for designing of air pollution control strategies.

Metformin suppresses calcium oxalate crystal-induced kidney injury by promoting Sirt1 and M2 macrophage-mediated anti-inflammatory activation

Dear Editor,Kidney stones are one of the most common clinical diseases in urology.Approximately 80%of renal calculi are composed of calcium oxalate(CaOx)crystals,which are gradually deposited in the medullary collecting duct or in the renal interstitium,causing nephrocalcinosis.1 Although CaOx nephrocalcinosis is usually asymptomatic.

The brassinosteroid signaling component SlBZR1 promotes tomato fruit ripening and carotenoid accumulation

The plant hormone ethylene is essential for climacteric fruit ripening, although it is unclear how other phytohormones and their interactions with ethylene might affect fruit ripening. Here, we explored how brassinosteroids(BRs) regulate fruit ripening in tomato(Solanum lycopersicum) and how they interact with ethylene. Exogenous BR treatment and increased endogenous BR contents in tomato plants overexpressing the BR biosynthetic gene SlCYP90B3promoted ethylene production and fruit ripening.Genetic analysis indicated that the BR signaling regulators Brassinazole-resistant1(SlBZR1) and BRI1-EMS-suppressor1(SlBES1) act redundantly in fruit softening. Knocking out Sl BZR1 inhibited ripening through transcriptome reprogramming at the onset of ripening. Combined transcriptome deep sequencing and chromatin immunoprecipitation followed by sequencing identified 73 Sl BZR1-repressed targets and 203 Sl BZR1-induced targets involving major ripening-related genes, suggesting that Sl BZR1 positively regulates tomato fruit ripening.Sl BZR1 directly targeted several ethylene and carotenoid biosynthetic genes to contribute to the ethylene burst and carotenoid accumulation to ensure normal ripening and quality formation. Furthermore,knock-out of Brassinosteroid-insensitive2(Sl BIN2),a negative regulator of BR signaling upstream of Sl BZR1, promoted fruit ripening and carotenoid accumulation. Taken together, our results highlight the role of Sl BZR1 as a master regulator of tomato fruit ripening with potential for tomato quality improvement and carotenoid biofortification.

A novel cartridge for nucleic acid extraction,amplification and detection of infectious disease pathogens with the help of magnetic nanoparticles

Nucleic acid detection(NAD)based on real-time polymerase chain reaction(real-time PCR)is gold standard for infectious disease detection.Magnetic nanoparticles(MNPs)are widely used for nucleic acid extraction(NAE)because of their excellent properties.Microfluidic technology makes automated NAD possible.However,most of the NAD microfluidic chips are too complex to be applied to point-of-care(POC)testing.In this paper,a simple-structure cartridge was developed for POC detection of infectious diseases.This self-contained cartridge can be divided into a magnetic-controlled NAE part,a valve-piston combined fluidic control part and a PCR chip,which is able to extract nucleic acid from up to 500μL of liquid samples by MNPs and finish the detection process from“sample in”to“answer out”automatically.Performance tests of the cartridges show that it met the demands of automated NAD.Results of on-cartridge detection of hepatitis B virus(HBV)demonstrated that this system has good uniformity and no cross-contamination between different cartridges,and the limit of detection(LOD)of this system for HBV in serum is 50 IU/mL.Multiplex detections of severe acute respiratory syndrome coronaviruses 2(SARS-CoV-2)with a concentration of 500 copies/mL were carried out on the system and 100%positive detection rate was achieved.

哨兵5号欧洲业务二氧化硫产品在中国的准确性评估

2017年11月欧洲空间局发射的哨兵5号搭载了新一代光谱仪(对流层大气监测仪,TROPOMI),可实现包括二氧化硫(SO2)在内的对流层大气成分高空间分辨率全球监测.欧洲空间局提供的SO2数据(TROPOMI欧洲业务SO2产品)对中国大气污染监测有重要支撑作用,然而数据有效性尚需验证.通过对比地基多轴差分吸收光谱仪数据(MAX-DOAS)和生态环境部中国环境监测总站(国控站点)数据,发现该数据明显高估中国北方SO2浓度.相对于地基MAX-DOAS站点高估61%~140%,且相关性小于0.5,相对于国控站点平均高估约54.6%.进一步研究表明,反演算法是造成显著性差异的原因.为了检验TROPOMI高光谱数据的适用性,自主研发的最优化估计方法也用于处理光谱数据,反演得到的SO2柱总量(中国科学技术大学(中国科大)SO2产品)与地基MAX-DOAS的偏差大幅降低(-4.8%~22%),相关性显著提高(0.72~0.89).与国控站点数据的平均偏差更小,为-25.8%.TROPOMI欧洲业务SO2产品相对于中国科大SO2产品偏高41.3%,并且标示了更大范围的重污染区域,与中国SO2大幅减排的事实相悖.而中国科大SO2产品大大提高TROPOMI结果在中国应用的准确性和价值.

异源过表达OsATG8b基因提高转基因拟南芥的氮/碳胁迫耐受性和产量

氮素是参与植物生长发育的一种重要元素,对植物的产量和品质具有重要作用。自噬是真核生物中一种保守的细胞组分降解-循环再利用途径,在植物生长发育和籽粒形成期间的氮素再动员过程中发挥作用。我们鉴定到水稻(Oryza sativa)自噬核心基因OsATG8b,并获得2个独立的35S-OsATG8b转基因拟南芥(Arabidopsisthaliana)纯合株系。研究表明OsATG8b基因响应低氮胁迫处理,过表达OsATG8b基因促进转基因拟南芥的生长发育,使莲座叶增大,单株产量显著提高(15.16%)。进一步研究表明,过表达OsATG8b能够显著增强缺氮胁迫下转基因拟南芥叶片中的自噬活性,从而有效缓解氮胁迫和碳胁迫对转基因拟南芥造成的生长抑制。因此, OsATG8b是提高氮素利用效率和产量的候选基因。

First observation of tropospheric nitrogen dioxide from the Environmental Trace Gases Monitoring Instrument onboard the GaoFen-5 satellite

The Environmental Trace Gases Monitoring Instrument(EMI)is the first Chinese satellite-borne UV–Vis spectrometer aiming to measure the distribution of atmospheric trace gases on a global scale.The EMI instrument onboard the GaoFen-5 satellite was launched on 9 May 2018.In this paper,we present the tropospheric nitrogen dioxide(NO2)vertical column density(VCD)retrieval algorithm dedicated to EMI measurement.We report the first successful retrieval of tropospheric NO_(2) VCD from the EMI instrument.Our retrieval improved the original EMI NO_(2) prototype algorithm by modifying the settings of the spectral fit and air mass factor calculations to account for the on-orbit instrumental performance changes.The retrieved EMI NO_(2) VCDs generally show good spatiotemporal agreement with the satellite-borne Ozone Monitoring Instrument and TROPOspheric Monitoring Instrument(correlation coefficient R of ~0.9,bias<50%).A comparison with ground-based MAX-DOAS(Multi-Axis Differential Optical Absorption Spectroscopy)observations also shows good correlation with an R of 0.82.The results indicate that the EMI NO_(2) retrieval algorithm derives reliable and precise results,and this algorithm can feasibly produce stable operational products that can contribute to global air pollution monitoring.

A Green Biocompatible Fabrication of Highly Porous Functional Ceramics with High Strength and Controllable Pore Structures

A green biocompatible foaming method utilizing natural coconut oil and cornstarch was developed to fabricate highly porous functional ceramics with controllable strengths and pore structures. The porosity of Al2O3 ceramics prepared via this method reached 79.6%–86.9% while these ceramics maintained high compressive strengths of 2.2–5.5 MPa. More importantly, porous Al2O3 ceramic with a pore size gradient was also readily fabricated by casting serial layers of foams that were set for different time periods.The potential applications of porous Al2O3 and HA ceramics fabricated by this green foaming method including scaffolds for oil cleaning and cell culture, respectively, were also demonstrated.

A flexible conductive hybrid elastomer for high-precision stress/strain and humidity detection

Flexible and environment-responsive materials are essential for a large number of applications from artificial skin to wearable devices. The present study develops a flexible, ultra-low cost conductive hybrid elastomer(CHE), which possesses high responsive capabilities to stress/strain and humidity. CHE was composed of polydimethylsiloxane(PDMS) and starch hydrogel(SH), enabling great elasticity(56 kPa),high conductivity(10^(-2)S/m) and high sensitivity to external stimuli(gauge factor of CHE under stress and strain are 0.71 and 2.22, respectively, and sensitivity to humidity is 1.2 × 10^(-6)S/m per RH%). These properties render CHE a promising candidate for artificial skin and wearable electronics applications of continuously monitoring environmental information.

Vertical distribution and temporal evolution of formaldehyde and glyoxal derived from MAX-DOAS observations:The indicative role of VOC sources

Formaldehyde(HCHO)and glyoxal(CHOCHO)are important oxidization intermediates of most volatile organic compounds(VOCs),but their vertical evolution in urban areas is not well understood.Vertical profiles of HCHO,CHOCHO,and nitrogen dioxide(NO_(2))were retrieved from ground-based Multi-Axis Differential Optical Absorption Spectroscopy(MAXDOAS)observations in Hefei,China.HCHO and CHOCHO vertical profiles prefer to occur at higher altitudes compared to NO_(2),which might be caused by the photochemistry-oxidation of longer-lived VOCs at higher altitudes.Monthly means of HCHO concentrations were higher in summer,while enhanced amounts of NO_(2)were mainly observed in winter.CHOCHO exhibited a hump-like seasonal variation,with higher monthly-averaged values not only occurred in warm months(July-August)but also in cold months(November-December).Peak values mainly occurred during noon for HCHO but emerged in the morning for CHOCHO and NO_(2),suggesting that HCHO is stronger link to photochemistry than CHOCHO.We further use the glyoxal to formaldehyde ratio(GFR)to investigate the VOC sources at different altitudes.The lowest GFR value is almost found in the altitude from 0.2 to 0.4 km,and then rises rapidly as the altitude increases.The GFR results indicate that the largest contributor of the precursor VOC is biogenic VOCs at lower altitudes,while at higher altitudes is anthropogenic VOCs.Our findings provide a lot more insight into VOC sources at vertical direction,but more verification is recommended to be done in the future.

Chemical Modification of Silk Proteins: Current Status and Future Prospects

Silk extracted from the cocoon of silkworm has been used as textile materials for thousands of years.Recently,silk has been redefined as a protein-based biomaterial with great potential in biomedical applications owing to its excellent mechanical properties,biocompatibility,and biodegradability.With the advances in silk processing technologies,a broad range of intriguing silk-based functional biomaterials have been made and applied for various biomedical uses.However,most of these materials are based on natural silk proteins without chemical modification,leading to limited control of properties and functions(e.g.,biodegradability and bioactivity).A chemical toolbox for modifying the silk proteins is required to achieve versatile silk-based materials with precisely designed properties or functions for different applications.Furthermore,inspired by the traditional fine chemical industry based on synthetic chemistry,developing silk-based fine chemicals with special functions can significantly extend the applications of silk materials,particularly in biomedical fields.This review summarizes the recent progress on chemical modification of silk proteins,focusing on the methodologies and applications.We also discuss the challenges and opportunities of these chemically modified silk proteins.

In situ grown TiN/N-TiO_(2)composite for enhanced photocatalytic H_(2)evolution activity

Titanium nitride(TiN)decorated N-doped titania(N-TiO_(2))composite(TiN/N-TiO_(2))is fabricated via an in situ nitridation using a hydrothermally synthesized TiO_(2)and melamine(MA)as raw materials.After the optimization of the reaction condition,the resultant TiN/NTiO_(2)composite delivers a hydrogen evolution activity of up to 703μmol/h under the full spectrum irradiation of Xelamp,which is approximately 2.6 and 32.0 times more than that of TiO_(2)and TiN alone,respectively.To explore the underlying photocatalytic mechanism,the crystal phase,morphology,light absorption,energy band structure,element composition,and electrochemical behavior of the composite material are characterized and analyzed.The results indicate that the superior activity is mainly caused by the in situ formation of plasmonic TiN and N-TiO_(2)with intimate interface contact,which not only extends the spectral response range,but also accelerates the transfer and separation of the photoexcited hot charge carrier of TiN.The present study provides a fascinating approach to in situ forming nonmetallic plasmonic material/N-doped TiO_(2)composite photocatalysts for high-efficiency water splitting.

Exploring the impact of new particle formation events on PM_(2.5) pollution during winter in the Yangtze River Delta,China

New particle formation(NPF)events are an increasingly interesting topic in air quality and climate science.In this study,the particle number size distributions,and the frequency of NPF events over Hefei were investigated from November 2018 to February 2019.The proportions of the nucleation mode,Aitken mode,and accumulation mode were 24.59%,53.10%,and 22.30%,respectively,which indicates the presence of abundant ultrafine particles in Hefei.Forty-six NPF events occurred during the observation days,accounting for 41.82%of the entire observation period.Moreover,the favorable meteorological conditions,potential precursor gases,and PM_(2.5)range of the NPF events were analyzed.Compared to non-NPF days,the NPF events preferentially occurred on days with lower relative humidity,higher wind speeds,and higher temperatures.When the PM_(2.5) was 15–20,70–80,and105–115μg/m^(3),the frequency of the NPF events was higher.Nucleation mode particles were positively related to atmospheric oxidation indicated by ozone when PM_(2.5) ranged from 15 to 20μg/m^(3),and related to gaseous precursors like SO_(2) and NO_(2) when PM_(2.5)was located at 70-80 and 105–115μg/m^(3).On pollution days,NPF events did not directly contribute to the increase in the PM_(2.5) in the daytime,however,NPF events would occur during the night and the growth of particulate matter contributes to the nighttime PM_(2.5) contents.This could lead to pollution that lasted into the next day.These findings are significant to the improvement of our understanding of the effects of aerosols on air quality.