A review of ultra-high temperature heat-resistant energetic materials

Heat-resistant energetic materials refer to a type of energetic materials that possess a high melting point,high stability and operational safety. By studying the structures of these energetic materials has showed that the thermal stability can be enhanced by introducing amino groups to form intra/inter-molecular hydrogen bonds, constructing conjugate systems and designing symmetrical structures. This article aims to review the physical and chemical properties of ultra-high temperature heat-resistant energetic compounds and provide valuable theoretical insights for the preparation of ultra-high temperature heatresistant energetic materials. We also analyze the selected 20 heat-resistant energetic materials with decomposition temperatures higher than 350℃, serving as templates for the synthesis of various highperformance heat-resistant energetic materials.

Identification of new cotton fiber-quality QTL by multiple genomic analyses and development of markers for genomic breeding

Cotton fiber is one of the main raw materials for the textile industry.In recent years,many cotton fiber quality QTL have been identified,but few were applied in breeding.In this study,a genome wide association study(GWAS)of fiber-quality traits in 265 upland cotton breeding intermediate lines(GhBreeding),combined with genome-wide selective sweep analysis(GSSA)and genomic selection(GS),revealed 25 QTL.Most of these QTL were ignored by only using GWAS.The CRISPR/Cas9 mutants of GhMYB_D13 had shorter fiber,which indicates the credibility of QTL to a certain extent.Then these QTL were verified in other cotton natural populations,5 stable QTL were found having broad potential for application in breeding.Additionally,among these 5 stable QTL,superior genotypes of 4 showed an enrichment in most improved new varieties widely cultivated currently.These findings provide insights for how to identify more QTL through combined multiple genomic analysis to apply in breeding.

Population genomic data reveal low genetic diversity,divergence and local adaptation among threatened Reeves's Pheasant(Syrmaticus reevesii)

Population genomic data could provide valuable information for conservation efforts;however,limited studies have been conducted to investigate the genetic status of threatened pheasants.Reeves’s Pheasant(Syrmaticus reevesii)is facing population decline,attributed to increases in habitat loss.There is a knowledge gap in understanding the genomic status and genetic basis underlying the local adaptation of this threatened bird.Here,we used population genomic data to assess population structure,genetic diversity,inbreeding patterns,and genetic divergence.Furthermore,we identified candidate genes linked with adaptation across the current distribution of Reeves’s Pheasant.The present study assembled the first de novo genome sequence of Reeves’s Pheasant and annotated 19,458 genes.We also sequenced 30 individuals from three populations(Dabie Mountain,Shennongjia,Qinling Mountain)and found that there was clear population structure among those populations.By comparing with other threatened species,we found that Reeves’s Pheasants have low genetic diversity.Runs of homozygosity suggest that the Shennongjia population has experienced serious inbreeding.The demographic history results indicated that three populations experienced several declines during the glacial period.Local adaptative analysis among the populations identified 241 candidate genes under directional selection.They are involved in a large variety of processes,including the immune response and pigmentation.Our results suggest that the three populations should be considered as three different conservation units.The current study provides genetic evidence for conserving the threatened Reeves’s Pheasant and provides genomic resources for global biodiversity management.

Heterostructured Mn_(3)O_(4)-MnS Multi-Shelled Hollow Spheres for Enhanced Polysulfide Regulation in Lithium-Sulfur Batteries

Constructing heterojunctions and hollow multi-shelled structures can render materials with fascinating physicochemical properties,and have been regarded as two promising strategies to overcome the severe shuttling and sluggish kinetics of polysulfide in lithium-sulfur(Li-S)batteries.However,a single strategy can only take limited effect.Modulating catalytic hosts with synergistic effects are urgently desired.Herein,Mn_(3)O_(4)-MnS heterogeneous multi-shelled hollow spheres are meticulously designed by controlled sulfuration of Mn2O3 hollow spheres,and then applied as advanced encapsulation hosts for Li-S batteries.Benefiting from the separated spatial confinement by hollow multi-shelled structure,ample exposed active sites and built-in electric field by heterogeneous interface,and synergistic effects between Mn_(3)O_(4)(strong adsorption)and MnS(fast conversion)components,the assembled battery achieves prominent rate capability and decent cyclability(0.016%decay per cycle at 2 C,1000 cycles).More crucially,satisfactory areal capacity reaches up to 7.1 mAh cm^(-2)even with high sulfur loading(8.0 mg cm^(-2))and lean electrolyte(E/S=4.0 pL mg^(-1))conditions.This work will provide inspiration for the rational design of hollow multi-shelled heterostructure for various electrocatalysis applications.

Using non-destructive sampling to evaluate the population genomic status of captive Brown Eared Pheasants

Evaluating the genetic status of threatened species is an essential task in conservation genetics.However,the genetic status of threatened species has been mostly evaluated through techniques that fail to estimate genetic diversity at the whole genomic level.Next generation sequencing can meet this demand,but high quality samples such as blood or muscle tissues are required.However,it is difficult to collect such samples from threatened species because sampling work may impact their health.Therefore,it is essential to design a workflow to evaluate the whole genomic status of threatened species using non-destructive sampling.Even though non-destructive sampling has been used in traditional barcoding technique,the barcoding technique cannot evaluate the whole genomic status.Brown Eared Pheasant(Crossoptilon mantchuricum)is an endangered species,with captive populations maintained in Taiyuan Zoo,China,and Europe.However,the genetic diversity,inbreeding pattern,and mutation load of these two populations are unclear.To uncover the genetic status of these two captive populations,we applied 2b-RAD technology to evaluate the genomic status of these populations using feathers as samples.The feathers could be collected by non-destructive sampling.The results indicate that the Taiyuan Zoo population has a lower genetic diversity and higher inbreeding coefficient than the European population.The Taiyuan Zoo population has lethal mutations when homozygous.The current project uses a non-destructive sampling technique to evaluate the whole genomic status of the two captive populations,providing a paradigm for conservation genetics,which will facilitate the development of conservation biology.

Insight into Hydrolytic Stability and Tribological Properties of B-N Coordination Tung Oil-Based Lubricant Additive in Water

A tung oil-based boron-nitrogen coordination polymer(TWE-BN)was specially designed and synthesized as a highly efficient water-based lubricant additive,which has been beneficial to both energy conservation and conducive to environmental protection.Its hydrolysis stability and tribological properties in water were investigated.To better research the lubricating properties,and thus to understand the interaction between the surface and the lubricating additives.Herein,both experimental and theoretical computations based on density functional theory(DFT)were performed.The addition of TWE-BN reduces the water friction coefficient and wear scar diameter,and the maximum non-seizure load increased from 93 to 726 N.Moreover,the anti-corrosion ability on copper was classified as 1b level.The stainless-steel surface was analyzed using scanning electron microscopy(SEM)and X-ray photoelectron spectroscopy(XPS).In hydrolytic stability testing,TWE-BN was better than nitrogen-free tung oil-based lubricant additive(TWE-B)and remained non-hydrolyzed for at least 15 days,implying the feasibility of tung oil-based boron-nitrogen coordination as highly effective and hydrolytic stability lubricant additives.

Plate tectonic control on the formation and tectonic migration of Cenozoic basins in northern margin of the South China Sea

The tectonic evolution history of the South China Sea(SCS) is important for understanding the interaction between the Pacific Tectonic Domain and the Tethyan Tectonic Domain,as well as the regional tectonics and geodynamics during the multi-plate convergence in the Cenozoic.Several Cenozoic basins formed in the northern margin of the SCS,which preserve the sedimentary tectonic records of the opening of the SCS.Due to the spatial non-uniformity among different basins,a systematic study on the various basins in the northern margin of the SCS constituting the Northern Cenozoic Basin Group(NCBG) is essential.Here we present results from a detailed evaluation of the spatial-temporal migration of the boundary faults and primary unconformities to unravel the mechanism of formation of the NCBG.The NCBG is composed of the Beibu Gulf Basin(BBGB),Qiongdongnan Basin(QDNB),Pearl River Mouth Basin(PRMB) and Taixinan Basin(TXNB).Based on seismic profiles and gravity-magnetic anomalies,we confirm that the NE-striking onshore boundary faults propagated into the northern margin of the SCS.Combining the fault slip rate,fault combination and a comparison of the unconformities in different basins,we identify NE-striking rift composed of two-stage rifting events in the NCBG:an early-stage rifting(from the Paleocene to the Early Oligocene) and a late-stage rifting(from the Late Eocene to the beginning of the Miocene).Spatially only the late-stage faults occurs in the western part of the NCBG(the BBGB,the QDNB and the western PRMB),but the early-stage rifting is distributed in the whole NCBG.Temporally,the early-stage rifting can be subdivided into three phases which show an eastward migration,resulting in the same trend of the primary unconformities and peak faulting within the NCBG.The late-stage rifting is subdivided into two phases,which took place simultaneously in different basins.The first and second phase of the early-stage rifting is related to back-arc extension of the Pacific subduction retreat system.The third phase of the earlystage rifting resulted from the joint effect of slab-pull force due to southward subduction of the proto-SCS and the back-arc extension of the Pacific subduction retreat system.In addition,the first phase of the late-stage faulting corresponds with the combined effect of the post-collision extension along the Red River Fault and slab-pull force of the proto-SCS subduction.The second phase of the late-stage faulting fits well with the sinistral faulting of the Red River Fault in response to the Indochina Block escape tectonics and the slab-pull force of the proto-SCS.

家庭文化资本对学前教育机会的影响——基于CFPS数据的实证研究

保证学前教育机会是实现学前教育价值的前提。家庭对儿童获得学前教育机会有重要影响。本研究利用中国家庭追踪调查(CFPS 2016)数据,基于文化资本的综合测度,采用多元Logit回归方法检验家庭文化资本与学前教育机会的关系,结果发现家庭文化资本越丰富,儿童获得学前教育机会的可能性会显著增加;相比其他资本,家庭文化资本对学前教育机会的影响更大。分样本回归结果显示,家庭文化资本对农村儿童和女童的影响更大。家庭应重视自身文化资本的内涵发展,提高对学前教育阶段重要性的认识和家长陪伴质量,尽力为儿童提供丰富的文化产品和创建良好的家庭养育环境。政府和社会应善用本地公共文化资源,提升社区中家庭的文化资本,同时应丰富普惠性教育资源,增加对学前教育的投入,积极帮扶弱势家庭子女获得均等的学前教育机会。

Modification strategies on transition metal-based electrocatalysts for efficient water splitting

Electrocatalytic water splitting driven by electrocatalysts is recognized as a promising strategy to generate clean hydrogen fuel.Searching and constructing high-efficient and low-cost electrocatalysts is vital in the practical applications of electrocatalytic water splitting.Although transition metal-based materials have been considered as promising electrocatalysts,the satisfactory activities are usually not built on the bulk materials,but strongly relying on elaborately designing these electrocatalysts.Herein,the recent theoretical and experimental progress on modification strategies to improve the intrinsic activities is summarized,especially including element doping,phase engineering,structure cooperation,interface engineering,vacancy engineering,strain engineering and self-functionalization.Finally,the future opportunities and challenges on these modification strategies are also proposed.Overall,it is anticipated that these modification strategies offer some new understandings on rationally constructing non-noble electrocatalysts for efficient electrocatalytic water splitting.

Pentazolate Anion Cyclo-N5^-:Development of a New Energetic Material

五唑,作为氮杂五元环中最后被发现的结构单元,备受学术界的关注[1,2],五唑中的五个氮原子以N-N和N=N键形成的五元环结构具有芳香性,从而使其具有较好的热稳定性[3],以其为基础合成得到的多数金属盐和非金属盐的分解温度均高于100℃,这是除N2、N5^-之外,唯一一个常温稳定的全氮结构[4-7]。

Effects of climate,land use and land cover changes on soil loss in the Three Gorges Reservoir area,China

Climate,land use and land cover(LULC)changes are among the primary driving forces of soil loss.Decoupling their effects can help in understanding the magnitude and trend of soil loss in response to human activities and ecosystem management.Here,the RUSLE model was applied to estimate the spatial-temporal variations of soil loss rate in the Three Gorges Reservoir(TGR)area during 2001-2015,followed by a scenario design to decouple the effects of climate and LULC changes.The results showed that increasing rainfall generated as much as 2.90×10^(7)t soil loss in the TGR area.However,such effect was offset by changes in LULC particularly afforestation,which retained about 1.10×10^(7)t soil annually.Other human activities such as dam development and urbanization aggravated soil loss by as much as 1.40×10^(6)t annually.Because of land use policies that favor economic development,distinct spatial variances of soil loss were observed in TGR area.Soil loss in some counties located downstream of the TGR area(i.e.,close to the dam)was more influenced by dam development,but soil loss in the other counties was more influenced by urbanization.As climate change(i.e.,increasing rainfall)did not affect plant performance in TGR area,our findings suggested that ecological restoration was more beneficial to curb the amount of soil loss caused by urbanization and dam construction.

Seasonal increase of nest height of the Silver-throated Tit(Aegithalos glaucogularis): can it reduce predation risk?

Background: Nest predation is usually the main cause of bird nest failure. ‘Predation avoidance hypothesis' of nestsite selection predicts that birds should prefer nest-sites with higher nesting success. We investigated the relationship between nest height and nest fate in Silver-throated Tits(Aegithalos glaucogularis) and asked whether the seasonal change of nest height was adaptive by simultaneously analyzing the seasonal variation of predation rates of the nests.Methods: We monitored nests of the Silver-throated Tit across seven breeding seasons in the Dongzhai National Nature Reserve in Henan Province of China. We compared the difference of nesting success among nests of different heights and analyzed the effect of nesting date on nest height and nest predation rates.Results: The overall nesting success rate was 24.1%(n ds and mammals, followed by snakes(9.11%= 623). Among the failed nests(n). The average height of successf= 472), 59.75% were predated by birul nests was significantly lower than that of predated nests. As the season progresses, the height of the nests increased significantly, companied by the decrease in nesting success. Daily survival rate of the nests also decreased with the progression of the season, regardless of breeding stages.Conclusions: Our findings suggest that nest height is an important factor influencing the nesting success of Silverthroated Tits. However, the seasonal increase of nest height appears inconsistent to the ‘predation avoidance hypothesis', because it is associated with higher predation rates. The reason for this maladaptive behavior remains to be explored in future studies.

The biaxial compression mechanical properties of crushed rock

Crushed rock subgrade, as one of the roadbed-cooling methods, has been widely used in the Qinghai-Tibet Railway. Much attention has been paid on the cooling effect of crushed rock; however, the mechanical properties of crushed rock are somehow neglected. Based on the discrete element method, biaxial compression test condition for crushed rock is com- piled in FISH language in PFC2D, and the natural shape of crushed rock is simulated with super particle ＂cluster＂. The ef- fect of particle size, crushed rock strength and confining pressure level on overall mechanical properties of the crushed rock aggregate are respectively analyzed. Results show that crushed rock of large particle size plays an essential frame- work role, which is mainly responsible for the deformation of crushed rock aggregate. The strength of gravel has a great influence on overall mechanical properties which means that strength attenuation caused by the freeze thaw cycles cannot be ignored. The stress-strain curves can be divided into two stages including shear contraction and shear expansion at different confining pressures.

Characterization of novel microsatellite markers of the Emei Shan Liocichla using restriction site-associated DNA sequencing

Background:The Emei Shan Liocichla(Liocichla omeiensis) is an endemic bird species to southwestern China with a small geographic range. However, little was known about the genetic status of this threatened species.Methods:We applied restriction-site-associated DNA sequencing(RAD-Seq) for rapid mass identification of microsatellite markers of the Emei Shan Liocichla.Results:A total of 11,564 microsatellite sequences were obtained, 600 random loci were designed for screening and 24 polymorphic microsatellite loci were selected for further validation. The average allele number, average observed heterozygosity and average expected heterozygosity were relatively low in our samples, which were 6.08, 0.6618 and 0.7048, respectively, indicating that the Emei Shan Liocichla might have lost some genetic diversity. Further analyses suggested that the populations distributed on two mountains(Daxiangling and Xiaoliangshan) showed a modest degree of genetic differentiation.Conclusions:These novel microsatellite markers provided valuable preliminary knowledge regarding the genetic status of the Emei Shan Liocichla and can be useful in further studies, as well as in the management and conservation of this species.

Multilocus phylogeography and ecological niche modeling suggest speciation with gene flow between the two Bamboo Partridges

Background:Understanding how species diversify is a long-standing question in biology.The allopatric speciation model is a classic hypothesis to explain the speciation process.This model supposes that there is no gene flow during the divergence process of geographically isolated populations.On the contrary,the speciation with gene flow model supposes that gene flow does occur during the speciation process.Whether allopatric species have gene flow during the speciation process is still an open question.Methods:We used the genetic information from 31 loci of 24 Chinese Bamboo Partridges(Bambusicola thoracicus)and 23 Taiwan Bamboo Partridges(B.sonorivox)to infer the gene flow model of the two species,using the approxi-mate Bayesian computation(ABC)model.The ecological niche model was used to infer the paleo-distribution during the glacial period.We also tested whether the two species had a conserved ecological niche by means of a back-ground similarity test.Results:The genetic data suggested that the post-divergence gene flow between the two species was terminated before the mid-Pleistocene.Furthermore,our ecological niche modeling suggested that their ecological niches were highly conserved,and that they shared an overlapping potential distribution range in the last glacial maximum.Conclusions:The allopatric speciation model cannot explain the speciation process of the two Bamboo Partridges.The results of this study supported a scenario in which speciation with gene flow occurring between the allopatric species and have contributed to our understanding of the speciation process.

Research activity does not affect nest predation rates of the Silver-throated Tit,a passerine bird building domed nests

Background:Research activities have often been thought to potentially influence avian nesting success by increasing nest predation rates.Although recent studies of species building open nests and cavity nests suggest that research disturbance does not generally induce nest predation,whether it is also the case in species building domednests remains unknown.In birds,domed-nest species exist in about half of the passerine families,and research disturbance to the domed nests may differ from that to the nests of other types for their different nest structures.Methods:We investigated if research activities affected nest predation rate by analyzing the relationships of the daily nest survival rate with the research activities at the egg and nestling stages of a domed-nest species,the Silverthroated Tit(Aegithalos glaucogularis).Results:Our results showed that nest daily survival rate was significantly affected by the laying date and nest age during the egg stage,and by the hatching date only during the nestling stage.By contrast,there were no significant effects of research activities,in terms of visiting nests and filming nests,on the nest survival of the Silver-throated Tit at both the egg and nestling stages.Conclusions:Our results coincide with the findings in species building other types of nests that research activities do not always have negative effects on avian nesting success.

分阶段交通荷载作用下盐渍土动力特性研究

盐渍土路基不仅需要承受外界环境改变带来的影响,还需要经历循环往复的交通荷载作用。而交通荷载具有一定的时段性,通常是日间车流量大,夜间车流量小。土体的动力特性会随着交通荷载的加载次数而发生改变。通过开展持续性和分阶段加载条件下的动三轴试验,对过盐渍土在不同加载方式下的累积变形和动剪切模量进行分析并作对比研究,并分析停振阶段对盐渍土动力特性的影响。试验结果表明:分阶段加载对盐渍土的动力特性有明显的影响。持续性和分阶段加载条件下,试样均逐步达到了压密稳定状态;两种加载方式下累积应变的变化规律相似,但是停振期的存在会使后续振动阶段的累积应变增长变慢;不同加载方式下,盐渍土的动剪切模量表现出的变化规律存在明显差异;振动期间产生的变形能够在停振阶段得到部分恢复,从而使得累积变形和动剪切模量的变化出现明显的停滞与拐点。

Functional and phylogenetic structures of pheasants in China

Biodiversity has been subjected to increasing anthropogenic pressures.It is critical to understand the different processes that govern community assembly and species coexistence under biogeographic processes and anthropogenic events.Pheasants(Aves:Phasianidae)are highly threatened birds and China supports the richest pheasant species worldwide.Unravelling the spatial patterns and underlying factors associated with multidimensional biodiversity of species richness(SR),functional diversity(FD),and phylogenetic diversity(PD)of pheasants in China is helpful to understand not only the processes that govern pheasant community assembly and species coexistence,but also pheasant biodiversity conservation.We used a total of 45 pheasant species in China and analyzed the SR,FD,PD,and functional and phylogenetic structures by integrating species distribution maps,functional traits and phylogenies based on 50 km×50 km grid cells.We further used simultaneous autoregressive(SAR)models to explore the factors that determined these patterns.The southern Qinghai-Tibetan Plateau(QTP),Hengduan Mountains,southwestern Mountains,the east of the Qilian Mountains,the Qinling,southern China displayed higher SR,FD,and PD,which were determined by elevation,habitat heterogeneity,temperature seasonality,and vegetation cover.Elevation primarily determined the functional and phylogenetic structures of the pheasant communities.Assemblages in the highlands were marked by functional and phylogenetic clustering,particularly in the QTP,whereas the lowlands in eastern China comprised community overdispersion.Clustered pheasant assemblages were composed of young lineages.Patterns of functional and phylogenetic structures and richness-controlled functional and phylogenetic diversity differed between regions,suggesting that phylogenetic structures are not a good proxy for identifying functional structures.We revealed the significant role of elevation in pheasant community assemblages in China.Highlands interacted with community clustering,whereas lowlands interacted with overdispersion,supporting the environmental filtering hypothesis.Biogeographical drivers other than anthropogenic factor determined biodiversity of pheasants at the present scale of China.This study provides complementary background resources for multi-dimensional pheasant biodiversity and provides insights into avian biodiversity patterns in China.

PEST Analysis on Dark Tourism Development in China

In domestic and foreign literature about the dark tourism,there are few papers about the dark tourism in China.At present,the study on the dark tourism in China remains at the starting stage.Most studies analyzed development of the dark tourism by SWOT method.No scholar has made analysis on the dark tourism development by PEST(political,economic,social and technological factor) analysis method.China is a large country rich in dark tourism resources.However,the theoretical researches of dark tourism lag behind the practical development.Therefore,it is necessary and urgent to study the development of dark tourism in China.Besides,the dark tourism is a special tourism resource and product,and its researches will further promote prosperity of tourism,push forward social development.Using PEST method,this paper analyzed development of the dark tourism from political,economic,social and technological factors,and it came up with pertinent recommendations.

CEPC Technical Design Report

The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 30 GeV Linac,a 1.1 GeV Damping Ring,a Booster capable of achieving energies up to 180 GeV,and a Collider operating at varying energy modes(Z,W,H,and tt).The Linac and Damping Ring are situated on the surface,while the subterranean Booster and Collider are housed in a 100 km circumference underground tunnel,strategically accommodating future expansion with provisions for a potential Super Proton Proton Collider(SPPC).The CEPC primarily serves as a Higgs factory.In its baseline design with synchrotron radiation(SR)power of 30 MW per beam,it can achieve a luminosity of 5×10^(34)cm^(-2)s^(-1)per interaction point(IP),resulting in an integrated luminosity of 13 ab^(-1)for two IPs over a decade,producing 2.6 million Higgs bosons.Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons,facilitating precise measurements of Higgs coupling at sub-percent levels,exceeding the precision expected from the HL-LHC by an order of magnitude.This Technical Design Report(TDR)follows the Preliminary Conceptual Design Report(Pre-CDR,2015)and the Conceptual Design Report(CDR,2018),comprehensively detailing the machine's layout,performance metrics,physical design and analysis,technical systems design,R&D and prototyping efforts,and associated civil engineering aspects.Additionally,it includes a cost estimate and a preliminary construction timeline,establishing a framework for forthcoming engineering design phase and site selection procedures.Construction is anticipated to begin around 2027-2028,pending government approval,with an estimated duration of 8 years.The commencement of experiments and data collection could potentially be initiated in the mid-2030s.