2种聚烯烃的水平流淌燃烧行为及熔体流变性

聚合物熔融燃烧时会产生大量流滴熔体,严重影响燃烧行为和火灾危害,但是多数研究集中于垂直燃烧模式,仅少量研究探讨了几种生胶的水平燃烧行为。文中测定了聚乙烯和聚丙烯水平燃烧时的熔体流淌面积和质量损失速率,通过设计的锥形量热仪样品盒收集了水平流淌熔体并表征其熔融温度和剪切黏度。研究发现,与熔体流动受限相比,聚乙烯和聚丙烯的水平流淌燃烧面积增大约10倍,最大燃烧速率增加超过1倍。在50kW/m2热辐射作用下,聚乙烯和聚丙烯在临近着火时就出现熔体流淌现象,且水平燃烧流淌熔体分别占到试样初始质量的58%和42%,与垂直燃烧滴落熔体质量占比相近,流淌熔体的熔融温度比原聚合物低6.2℃,黏流活化能比原聚合物分别减小34.4%和29.9%。

Progress of Air Pollution Control in China and Its Challenges and Opportunities in the Ecological Civilization Era

China’s past economic growth has substantially relied on fossil fuels,causing serious air pollution issues.Decoupling economic growth and pollution has become the focus in developing ecological civilization in China.We have analyzed the three-decade progress of air pollution controls in China,highlighting a strategic transformation from emission control toward air quality management.Emission control of sulfur dioxide(SO2)resolved the deteriorating acid rain issue in China in 2007.Since 2013,control actions on multiple precursors and sectors have targeted the reduction of the concentration of fine particulate matter(PM2.5),marking a transition to an air-quality-oriented strategy.Increasing ozone(O3)pollution further requires O3 and PM2.5 integrated control strategies with an emphasis on their complex photochemical interactions.Fundamental improvement of air quality in China,as a key indicator for the success of ecological civilization construction,demands the deep de-carbonization of China’s energy system as well as more synergistic pathways to address air pollution and global climate change simultaneously.

Clinicopathological and prognostic role of MMP-9 in esophageal squamous cell carcinoma: a meta-analysis

Objective： Many studies reported that matrix metalloproteinase-9 （MMP-9） participated in the development of esophageal squamous cell carcinoma （ESCC） and resulted in poor prognosis, however, they all included few patients and had inconsistent results. So we conducted a meta-analysis to explore the correlation between overexpression of MMP-9 and the clinicopathological characteristics and overall survival （OS） of ESCC. Methods： PubMed, EMBASE, Web of Science, Chinese Biomedical Literature Database, Google Scholar and other databases were searched for relevant studies. The Newcastle-Ottawa quality assessment scale was used to assess the methodological quality of included study and RevMan 5.2 software was used to conduct meta-analysis. Results： A total of 35 studies were included, and the results of meta-analysis showed that overexpression of MMP-9 was associated with grade of differentiation [well/moderate vs. poor： odds ratio （OR）： 0.39, 95% confidence interval （CI）： 0.29-0.52; P〈0.00001], lymph node metastasis （negative vs. positive： OR： 0.24, 95% CI： 0.16-0.34; P〈0.00001）, TNM stage （T1/T2 vs. T3/T4： OR： 0.28, 95% CI： 0.14-0.54; P=0.0002）, the depth of invasion （T1/T2 vs. T3/T4： OR： 0.29, 95% CI： 0.17-0.49; P〈0.00001）, and vascular invasion of ESCC （negative vs. positive： OR： 0.35, 95% CI： 0.21-0.58; P〈0.0001）, and also associated with poor overall survival ofESCC （HR： 2.17, 95% CI： 1.32-3.57; P=0.002）. Subgroup analysis showed that more than 10% of carcinoma cell staining was associated with significant increase of mortality risk （HR： 2.44, 95 % CI： 1.16-5.15; P=0.02）, and sensitive analysis suggested that MMP-9 was an independent prognostic factor in ESCC （HR： 1.49, 95% CI： 1.16-1.91; P=0.002）. Conclusions：On the basis of limited evidence, overexpression of MMP-9 may be a potential independent prognosis factor of ESCC patients in Asia, and high-quality studies assessing the prognostic significance of MMP-9 for ESCC patients are still needed.

Genome size evolution of the extant lycophytes and ferns

Ferns and lycophytes have remarkably large genomes.However,little is known about how their genome size evolved in fern lineages.To explore the origins and evolution of chromosome numbers and genome size in ferns,we used flow cytometry to measure the genomes of 240 species(255 samples)of extant ferns and lycophytes comprising 27 families and 72 genera,of which 228 species(242 samples)represent new reports.We analyzed correlations among genome size,spore size,chromosomal features,phylogeny,and habitat type preference within a phylogenetic framework.We also applied ANOVA and multinomial logistic regression analysis to preference of habitat type and genome size.Using the phylogeny,we conducted ancestral character reconstruction for habitat types and tested whether genome size changes simultaneously with shifts in habitat preference.We found that 2 C values had weak phylogenetic signal,whereas the base number of chromosomes(x)had a strong phylogenetic signal.Furthermore,our analyses revealed a positive correlation between genome size and chromosome traits,indicating that the base number of chromosomes(x),chromosome size,and polyploidization may be primary contributors to genome expansion in ferns and lycophytes.Genome sizes in different habitat types varied significantly and were significantly correlated with habitat types;specifically,multinomial logistic regression indicated that species with larger 2 C values were more likely to be epiphytes.Terrestrial habitat is inferred to be ancestral for both extant ferns and lycophytes,whereas transitions to other habitat types occurred as the major clades emerged.Shifts in habitat types appear be followed by periods of genomic stability.Based on these results,we inferred that habitat type changes and multiple whole-genome duplications have contributed to the formation of large genomes of ferns and their allies during their evolutionary history.

Synthesis, structure, and properties of Ba9Co3Se(15) with one-dimensional spin chains

A new compound with one-dimensional spin chains, Ba9Co3Se(15), was synthesized under high pressure and high temperature conditions and systematically characterized via structural, transport and magnetic measurements. Ba9Co3Se(15) crystallizes in a hexagonal structure with the space group P-6c2(No. 188) and lattice constants of a = b = 9.6765 ? and c = 18.9562 ?. The structure consists of trimeric face-sharing octahedral CoSe6 chains, which are arranged in a triangular lattice in the ab-plane and separated by Ba atoms. The distance of the nearest neighbor of CoSe6 chains is very large, given by the lattice constant a = 9.6765 ?. The Weiss temperature Tθ associated with the intra-chain coupling strength is about -346 K. However, no long-range magnetic order but a spin glass transition at ~ 3 K has been observed. Our results indicate that the spin glass behavior in Ba9Co3Se(15) mainly arises from the magnetic frustration due to the geometrically frustrated triangular lattice.

Superconductivity in Topological Semimetal θ-TaN at High Pressure

Recently,θ-TaN was proposed to be a topological semimetal with a new type of triply degenerate nodal points.Here,we report studies of pressure dependence of transport,Raman spectroscopy and synchrotron x-ray diffraction on θ-TaN up to 61 GPa.We find that θ-TaN becomes superconductive above 24.6 GPa with Tc at 3.1 K.The θ-TaN is of n-type carrier nature with carrier density about 1.1 × 1020/cm3 at 1.2 GPa and 20 K, while the carrier density increases with the pressure and saturates at about 40 GPa in the measured range.However,there is no crystal structure transition with pressure up to 39 GPa,suggesting the topological nature of the pressure induced superconductivity.

Doping effect on the structure and physical properties of quasi-one-dimensional compounds Ba_(9)Co_(3)(Se_(1−x)S_(x))_(15)(x=0-0.2)

A series of samples of Ba_(9)Co_(3)(Se_(1−x)S_(x))_(15)(x=0,0.05,0.1,0.15,0.2)with quasi-one-dimensional(1D)structure were successfully synthesized under high-temperature and high-pressure conditions.The influence of partial substitution of S for Se on the structure,electronic transport,and magnetic properties of Ba_(9)Co_(3)(Se_(1−x)S_(x))_(15) has been investigated in detail.The x-ray diffraction data shows that the lattice constant decreases linearly with increasing S-doping level,which follows the Vegrad’s law.The doped S atoms preferentially occupy the site of Se atoms in CoSe6 octahedron.Physical properties measurements indicate that all the samples of Ba_(9)Co_(3)(Se_(1−x)S_(x))_(15) are semiconducting and display spin glass behavior.As the replacement of Se by smaller size S,although the inter-chain distance decreases,the electronic hopping between CoSe/S6 chains is weakened and leads to an increase of band gap from 0.75 eV to 0.86 eV,since the S-3p electrons are more localized than Se-4p ones.Ba_(9)Co_(3)(Se_(1−x)S_(x))_(15) exhibits 1D conducting chain characteristic.

Structure-Spin-Transport Anomaly in Quasi-One-Dimensional Ba9Fe3Te15 under High Pressure

Recently,a series of novel compounds Ba3MX5(M=Fe,Ti,V;X=Se,Te)with hexagonal crystal structures composed of quasi-1-dimensional(1D)magnetic chains has been synthesized by our research team using high-pressure and high-temperature methods.The initial hexagonal phases persist to the maximum achievable pressure,while spin configurations and magnetic interactions may change dramatically as a result of considerable reductions in interchain separations upon pressurization.These compounds therefore offer unique possibilities for studying the evolution of intrinsic electronic structures in quasi-1D magnetic systems.Here we present a systematic investigation of Ba9Fe3Te15,in which the interchain separations between trimerized 1D chains(~10.2Å)can be effectively modulated by external high pressure.The crystal structure especially along the 1D chains exhibits an abnormal expansion at^GPa,which accompanies trimerization entangled anomalous mixed-high-low spin transition.An insulator-metal transition has been observed under high pressure as a result of charge-transfer gap closing.Pressure-induced superconductivity emerges at 26 GPa,where the charge-transfer gap fully closes,3D electronic configuration forms and local spin fully collapses.

Chromosome-level genome assembly of Oncomelania hupensis: the intermediate snail host of Schistosoma japonicum

Background Schistosoma japonicum is a parasitic flatworm that causes human schistosomiasis, which is a significant cause of morbidity in China, the Philippines and Indonesia.Oncomelania hupensis (Gastropoda: Pomatiopsidae) is the unique intermediate host ofS. japonicum. A complete genome sequence ofO. hupensis will enable the fundamental understanding of snail biology as well as its co-evolution with theS. japonicum parasite. Assembling a high-quality reference genome ofO. hupehensis will provide data for further research on the snail biology and controlling the spread ofS. japonicum.Methods The draft genome was de novo assembly using the long-read sequencing technology (PacBio Sequel II) and corrected with Illumina sequencing data. Then, using Hi-C sequencing data, the genome was assembled at the chromosomal level. CAFE was used to do analysis of contraction and expansion of the gene family and CodeML module in PAML was used for positive selection analysis in protein coding sequences.Results A total length of 1.46 Gb high-qualityO. hupensis genome with 17 unique full-length chromosomes (2n = 34) of the individual including a contig N50 of 1.35 Mb and a scaffold N50 of 75.08 Mb. Additionally, 95.03% of these contig sequences were anchored in 17 chromosomes. After scanning the assembled genome, a total of 30,604 protein-coding genes were predicted. Among them, 86.67% were functionally annotated. Further phylogenetic analysis revealed thatO. hupensis was separated from a common ancestor ofPomacea canaliculata andBellamya purificata approximately 170 million years ago. Comparing the genome ofO. hupensis with its most recent common ancestor, it showed 266 significantly expanded and 58 significantly contracted gene families (P < 0.05). Functional enrichment of the expanded gene families indicated that they were mainly involved with intracellular, DNA-mediated transposition, DNA integration and transposase activity.Conclusions Integrated use of multiple sequencing technologies, we have successfully constructed the genome at the chromosomal-level ofO. hupensis. These data will not only provide the compressive genomic information, but also benefit future work on population genetics of this snail as well as evolutional studies betweenS. japonicum and the snail host.

Synergistic promotion of particulate matter reduction and production performance via adjusting electrochemical reactions in the zinc electrolysis industry

Heavy particulate matter (PM) pollution and high energy consumption are the bottlenecks of hydrometallurgy, especially in the electrolysis process. Therefore, an urgent need is to explore PM reduction methods with production performance co-benefits. This study presents three PM reduction methods based on controlling operating parameters, i.e., lowering electrolyte temperature, H2SO4 concentration, and current density of the cathode. The optimized conditions were also investigated using the response surface methodology to balance the PM reduction effect and Zn production. The results showed that lowering electrolyte temperature is the most efficient, with an 89.0% reduction in the PM generation flux (GFPM). Reducing H2SO4 concentration led to the minimum side effects on the current efficiency of Zn deposition (CEZn) or power consumption (PC). With the premise of non-deteriorating CEZn and PC, GFPM can be reduced by 86.3% at the optimal condition (electrolyte temperature = 295 K, H2SO4 = 110 g/L, current density = 373 A/m^(2)). In addition, the reduction mechanism was elucidated by comprehensively analyzing bubble characteristics, electrochemical reactions, and surface tension. Results showed that lower electrolyte temperature inhibited the oxygen evolution reaction (OER) and compressed gas volume. Lower H2SO4 concentration inhibited the hydrogen evolution reaction (HER) and reduced electrolyte surface tension. Lower current density inhibited both OER and HER by decreasing the reaction current. The inhibited gas evolutions reduced the microbubbles’ number and size, thereby reducing GFPM. These results may provide energy-efficient PM reduction methods and theoretical hints of exploring cleaner PM reduction approaches for industrial electrolysis.

Effects of acid deposition control in China:a review based on responses of subtropical forests

For many decades,acid deposition used to pose a significant regional air pollution challenge in China.After substantial emission control of anthropogenically derived sulfur and nitrogen containing gasses,both sulfur and nitrogen deposition,as well as the acid rain-affected area,have significantly decreased compared to their peak levels.Forests,particularly in the humid subtropics,are sensitive to acid deposition,as evidenced by soil acidification,sulfate and nitrate leaching in stream water,and elevated soil nitrous oxide emission.Reduction in the total deposition of sulfur and nitrogen,caused a significant decline in sulfate and nitrate leaching from subtropical forest and subsequently in sulfate and nitrate concentrations in stream water,although there was about a 5-year delay.This delay may be attributed to the desorption of accumulated sulfate and continued elevated mineralization of accumulated nitrogen pools.Emissions of nitrous oxide,a potent greenhouse gas,also declined in nitrogen-saturated subtropical forest soils,as soil water nitrate concentration decreased.Therefore,subtropical forests in China suffering from elevated acid deposition have begun to recover.Yet,the current levels of sulfur and nitrogen deposition continue to exceed the critical loads,i.e.,the assigned threshold levels in accordance with emission control policies,in more than 10%of the country’s land area,respectively,indicating remaining risks of acidification and eutrophication.Thus,further emission reductions are urgently needed,also because they will help achieving goals related to air quality and nitrous oxide emissions.

Design and preparation of highly crystalline K-intercalated W@PCN:an efficient material for aniline elimination

In this paper,we designed and prepared the polymeric carbon nitride-supported tungsten(W@PCN)materials.They were employed as the catalysts for photocatalytic oxidation of aniline in water.During the process,H_(2)O_(2)was initially generated via the PCN-catalyzed hydrophotolysis.Catalyzed by supported tungsten,aniline was oxidized by the in situ generated H_(2)O_(2)to obtain less toxicpoly aniline.

Assessment of China’s contributions to the Regional Network for Asian Schistosomiasis and Other Helminth Zoonoses:a questionnaire survey

Background:The Regional Network for Asian Schistosomiasis and Other Helminth Zoonoses(RNAS^(+))was established in 1998,which has developed close partnerships with Asian countries endemic for schistosomiasis and other helminthiasis in Asia.RNAS^(+)has provided an ideal regional platform for policy-makers,practitioners and researchers on the prevention,control and research of parasitic diseases in Asian countries.China,one of the initiating countries,has provided significant technical and financial support to the regional network.However,its roles and contributions have not been explored so far.The purpose of this study was to assess China's contributions on the supporting of RNAS^(+)development.Methods:An assessment research framework was developed to evaluate China’s contributions to RNAS^(+)in four aspects,including capacity building,funding support,coordination,and cooperation.An anonymous web-based questionnaire was designed to acquire respondents’basic information,and information on China’s contributions,challenges and recommendations for RNAS^(+)development.Each participant scored from 0 to 10 to assess China’s contribution:“0”represents no contribution,and“10”represents 100%contribution.Participants who included their e-mail address in the 2017-2019 RNAS^(+)annual workshops were invited to participate in the assessment.Results:Of 71 participants enrolled,41 responded to the survey.37(37/41,90.24%)of them were from RNAS^(+)member countries,while the other 4(4/41,9.76%)were international observers.Most of the respondents(38/41,92.68%)were familiar with RNAS^(+).Respondents reported that China’s contributions mainly focused on improving capacity building,providing funding support,coordination responsibility,and joint application of cooperation programs on RNAS^(+)development.The average scores of China’s contributions in the above four fields were 8.92,8.64,8.75,and 8.67,respectively,with an overall assessment score of 8.81(10 for a maximum score).The challenge of RNAS^(+)included the lack of sustainable funding,skills,etc.and most participants expressed their continual need of China’s support.Conclusions:This survey showed that China has played an important role in the development of RNAS^(+)since its establishment.This network-type organization for disease control and research can yet be regarded as a great potential pattern for China to enhance regional cooperation.These findings can be used to promote future cooperation between China and other RNAS^(+)member countries.

Advancing knowledge of One Health in China:lessons for One Health from China's dengue control and prevention programs

Background The emergence of dengue fever has prompted significant public health responses,highlighting the need for a comprehensive understanding of One Health in addressing vector-borne diseases.China's experience in dengue control and prevention programs offers valuable insights into the successful integration of multidisciplinary strategies.Aims The review aims to:(1)systematically analyze lessons from China's dengue control and prevention programs,focusing on the integration of these efforts with the One Health approach;(2)underscore the reasons of optimizing the dengue control and prevention program;(3)highlight the alignment of China's dengue control strategies with the One Health framework;(4)contribute to global efforts in combating dengue,providing scientific evidence and strategic recommendations for other regions facing similar challenges.Results Through a comprehensive literature review and expert interviews,this study found China's approach to dengue control and prevention implemented through a hierarchical system led by the government,with collaborative efforts across multiple departments.This multi-sectoral collaboration mechanism enables the technical interventions well executed by health and disease control institutions,optimizing the integration of multiple cost-effeteness approaches,such as case management,early detection and outbreak response,reducing local transmission,and minimizing severe cases and fatalities.It was found that community participation and public health education have played a vital role in raising awareness,promoting personal protective measures,and enhancing the overall effectiveness of control efforts.The implementation of these integrated interventions has resulted in reduced dengue cases and improved capacity of outbreak response.China's dengue control strategies under the One Health framework,with focus on interdisciplinary collaboration,incorporated environmental and ecological interventions,which reduced mosquito breeding sites and improved sanitation.The findings of the review underscore the need for continuous improvement in early warning systems,scientific research,and the adoption of the One Health approach to address emerging challenges posed by climate change and the cross-border spread of infectious diseases.Conclusion China's dengue control and prevention programs provide a compelling case study for the effective application of the One Health approach.By systematically analyzing the integration of multidisciplinary strategies,this review reveals valuable lessons on optimizing public health responses to vector-borne diseases.The alignment of these strategies with One Health principles not only enhances the effectiveness of dengue control efforts in China but also offers a framework that can be adapted by other regions facing similar challenges.Ultimately,the insights gained from this analysis contribute to the global fight against dengue,emphasizing the need for collaborative and holistic approaches in public health initiatives.

Global,regional,and national burden of upper respiratory infections,1990-2021:findings from the Global Burden of Disease study 2021

Background Upper respiratory infections(URIs)are common infectious diseases worldwide.Accurate and timely assessment of the disease burden of URIs is crucial for governments to develop comprehensive prevention and control strategies,and to allocate and utilize healthcare resources more efficiently.Methods For URIs in Global Burden of Disease(GBD)2021 database,age-standardized incidence rates(ASIR),age-standardized prevalence rates(ASPR),age-standardized mortality rates(ASMR),disability-adjusted life-years(DALYs),and case numbers for incidence,prevalence,deaths,and DALYs across the globe,five socio-demographic index(SDI)regions,21 geographical regions,and 204 countries and territories were provided and analyzed.Trends from 1990 to 2021 were described using the average annual percentage change(AAPC),and future URIs burden was projected with a Bayesian age-period-cohort(BAPC)model.Results From 1990 to 2021,there was a significant decline in global ASIR(APCC=-289.86,95%confidence interval[CI]:-298.59 to-281.12),ASPR(AAPC=-4.04,95%CI:-4.16 to-3.92),ASMR(AAPC=-0.02,95%CI:-0.02 to-0.03)and age-standardized DALY rate(AAPC=-0.75,95%CI:-0.76 to-0.74).The ASIR,ASPR,ASMR,and age-standardized DALY rate were high in elderly for both males and females,and both genders.Similarly,the number of incident cases,prevalence cases,deaths,and DALY cases for URIs was highest in children under five years.The ASMR and age-standardized DALY rate exhibited a negative correlation with SDI across 204 countries and territories in 2021.The ASIR and ASPR for URIs will show an upward trend from 2022 to 2050,while ASMR and age-standardized DALY rate are expected to decline.Low birth weight for gestation remains the leading contributor to deaths related to URIs.Conclusion Despite the global decline in URIs burden,significant challenges remain among the elderly population.These findings support the optimization and implementation of public health policies,including targeted vaccination and integrated One Health approaches to reduce the burden in high-risk populations.

柴达木盆地新生代地层年代框架与沉积-构造演化

柴达木盆地的新生代地层非常发育,保存了从新生代早期至第四纪之间连续、完整的沉积记录.更为重要的是,柴达木盆地中发育丰富的新生代动、植物化石,为利用磁性地层学与古生物地层学方法建立盆地尺度的新生代地层年代框架,揭示盆地沉积演化、构造变形,以及青藏高原隆升、扩展的过程和动力学机制提供了重要的年代学制约.然而,目前关于柴达木盆地新生代地层层序和地层时代的认识还存在诸多矛盾之处。本文在野外观测、测量的基础上,总结、分析了柴达木盆地近年发表的相对连续、完整(厚度≥4500m)的磁性地层剖面,厘定了柴达木盆地新生代各岩石地层单元的地质年代.在此基础上,我们发现柴达木盆地西缘可能自始新世开始沉积,中部自渐新世(约31Ma)开始沉积,晚渐新世-早中新世沉积范围扩大至盆地东部柴达木盆地大部分地区自渐新世(31~26Ma)开始沉降,接受沉积的现象表明,青藏高原东北缘受印度板块与欧亚板块碰撞的影响开始发生构造变形.中中新世(约15Ma)以来,柴达木盆地沉积速率显著增加,盆地周缘山脉强烈隆升,揭示印度板块与欧亚板块持续汇聚作用导致的地壳缩短开始主宰高原东北部的构造变形,使柴达木盆地及其周缘造山带成为青藏高原向东北方向扩展过程中最新的组成部分.

环境空气质量基准和标准制定方法及其对我国的启示

我国已经在大气污染治理方面取得了显著成效,空气质量明显改善,积累了先进的空气污染治理经验.现阶段,我国应逐步开启对环境空气质量基准的研究.本文详细介绍了国际上主要的三大类环境空气质量基准和标准的制定原则与方法,分别基于人体健康、植被暴露以及土壤/水体生态系统化学指标;汇总比较了国际上较常采用的一系列评价指标.在此基础上,对我国上述三方面的本土化基础研究进行综述,分析了我国开展环境空气质量基准研究的原则性路径,包括工作初期和完善体系的预期架构,指出工作初期制定基准的工作可以适当从简,但在工作基础逐渐丰富后,应当逐步细化的工作原则.此外,本文还对国内外环境空气标准的制定策略中采纳基准的情况进行了简要的比较和梳理,结合我国环境空气达标现状、管理体系和工作基础,面向“美丽中国”和“健康中国”的宏伟目标,提出在科学构建环境空气质量评估体系的过程中,既要考虑我国本土人群健康与生态独特的安全红线,又要注意基准向标准转化过程可能带来的管理难点,从而确保环境空气污染防治攻坚战稳步推进并取得胜利.

柴达木盆地路乐河剖面磁性地层年代及其构造变形

青藏高原东北缘的柴达木盆地发育巨厚的新生代地层.这些地层记录了印度与欧亚大陆碰撞以来青藏高原向东北方向扩展过程中的构造变形、地貌演化与气候变化等信息.通过高密度的样品采集、测试与分析,古地磁测年结果显示,柴达木盆地北缘新生代地层出露较为连续、完整的路乐河剖面(路乐河组层型剖面)沉积年龄为30.9~5.2 Ma.路乐河剖面沉积环境与沉积速率分析揭示盆地新生代以来经历了约31与15 Ma开始的两期显著的构造变形事件:渐新世的构造变形导致了柴达木盆地的形成;中中新世以来的强烈构造变形导致了柴达木盆地的变形与改造.

Chemical composition and source apportionment of PM10 and PM2.5 in different functional areas of Lanzhou,China

To elucidate the air pollution characteristics of northern China, airborne PM_10（atmospheric dynamic equivalent diameter ≤ 10 μm） and PM_（2.5）（atmospheric dynamic equivalent diameter ≤ 2.5 μm） were sampled in three different functional areas（Yuzhong County,Xigu District and Chengguan District） of Lanzhou, and their chemical composition（elements, ions, carbonaceous species） was analyzed. The results demonstrated that the highest seasonal mean concentrations of PM_10（369.48 μg/m^3） and PM_（2.5）（295.42 μg/m^3） were detected in Xigu District in the winter, the lowest concentration of PM_（2.5）（53.15 μg/m^3） was observed in Yuzhong District in the fall and PM_10（89.60 μg/m^3） in Xigu District in the fall.The overall average OC/EC（organic carbon/elemental carbon） value was close to the representative OC/EC ratio for coal consumption, implying that the pollution of Lanzhou could be attributed to the burning of coal. The content of SNA（the sum of sulfate, nitrate,ammonium, SNA） in PM_（2.5）in Yuzhong County was generally lower than that at other sites in all seasons. The content of SNA in PM_（2.5）and PM_10 in Yuzhong County was generally lower than that at other sites in all seasons（0.24–0.38）, indicating that the conversion ratios from precursors to secondary aerosols in the low concentration area was slower than in the area with high and intense pollutants. Six primary particulate matter sources were chosen based on positive matrix factorization（PMF） analysis, and emissions from dust, secondary aerosols, and coal burning were identified to be the primary sources responsible for the particle pollution in Lanzhou.

高效多孔碳基催化剂的研究进展及其在锌空气电池中应用

近年来,能源短缺问题日益突出,传统化石燃料使用过程中排放的二氧化碳大大加剧了全球变暖.锌空气电池作为一种新型能源,由于其低成本、高比能量密度、高安全性和环境友好等优点而受到广泛关注.然而,锌空气电池的发展速度缓慢,一个主要原因是阴极空气催化剂的催化效率低和稳定性差.本文总结了用于空气阴极的多孔碳基催化剂的最新研究进展.在对锌空气电池进行简要介绍后,从孔结构和杂原子掺杂两方面介绍了碳载体的结构和组成.根据孔径大小:微孔、介孔和大孔,详细介绍了锌空气电池中多孔碳的设计和制备.此外,还根据氮、氟、硫、磷和硼等杂原子类别,分别讨论了杂原子掺杂的合成策略以及相应电池性能.最后,本文对锌空气电池未来发展过程中的挑战和机遇进行了展望.