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Sihailongwan Maar Lake, located in Northeast China, is a candidate Global boundary Stratotype Section and Point (GSSP) for demarcation of the Anthropocene. The lake’s varved sediments are formed by alternating allogenic atmospheric inputs and authigenic lake processes and store a record of environmental and human impacts at a continental-global scale. Varve counting and radiometric dating provided a precise annual-resolution sediment chronology for the site. Time series records of radioactive (239,240Pu, 129I and soot 14C), chemical (spheroidal carbonaceous particles, polycyclic aromatic hydrocarbons, soot, heavy metals, δ13C, etc.), physical (magnetic susceptibility and grayscale) and biological (environmental DNA) indicators all show rapid changes in the mid-20th century, coincident with clear lithological changes of the sediments. Statistical analyses of these proxies show a tipping point in 1954 CE. 239,240Pu activities follow a typical unimodal globally-distributed profile, and are proposed as the primary marker for the Anthropocene. A rapid increase in 239,240Pu activities at 88 mm depth in core SHLW21-Fr-13 (1953 CE) is synchronous with rapid changes of other anthropogenic proxies and the Great Acceleration, marking the onset of the Anthropocene. The results indicate that Sihailongwan Maar Lake is an ideal site for the Anthropocene GSSP.

A peptide-based silicon nanowire array sensor for the specific detection of TNT was developed, and the effect of the biointerfacing linker was investigated.

The 1500-km-long Kunlun strike-slip fault is one of the largest and most active faults in the Tibetan Plateau. The eastward extrusion of Tibet has generated the 2001 Mw 7.8 Kunlunshan earthquake along the eastern Kunlun fault (elevation ≥ 4500 m) that produced the longest surface rupture yet recorded on land, ~400 km. The knowledge of past earthquake history and long-term fault behavior along the eastern Kunlun fault is still limited by short seismological records. Moreover, suitable sites for paleoseismological trenching are rarely available due to the active freeze-thaw action in such an extreme environment. Lacustrine paleoseismology, exploits lacustrine sediments to retrieve a much longer record of paleoseismic shaking, may shed light on earthquake occurrence and fault behavior along the eastern Kunlun fault.Lake Kusai is bounded by the eastern Kunlun fault in the north, and its north end was once ruptured by the 2001 Mw 7.8 Kunlunshan earthquake. Sedimentary sequence from the lake is characterized by layered sediments, thus an ideal site for lacustrine paleoseismology investigation. A 8.2 m-long core has been drilled from the lake in 2006. 210Pb/137Cs and AMS14C dating, and detailed varve counting confirm that the upper 165 cm of the drilled sedimentary sequence is varved and spans the last 2000 years. This sedimentary sequence is therefore ideal for event deposits recognition and high-resolution seismic record reconstruction. We identify sedimentary imprint of the 2001 Mw 7.8 earthquake and another 13 deeper horizons of in situ soft sediment deformations and micro-faults from the sedimentary sequence. The primary data reveals a clustered earthquake recurrence pattern with a mean recurrence interval of ~150 years on the central part of the eastern Kunlun fault. Keywords: Eastern Kunlun fault; Northern Tibetan Plateau; Lake Kusai; Varved lake sediment; Soft sediment deformation structure; Paleoseismic events.

Little attention has been paid to climate change in the marginal regions of the Asian summer monsoon (ASM) domain since Marine Isotope Stage (MIS) 3 (60-27 cal kyr BP). Here, based on the mineralogy and grain size of a 24-m-long sediment core retrieved from Jilantai Salt Lake, we provide a paleolake evolution record from a marginal region of the ASM domain over the past 47 kyr. Our results indicate that the lake was a brackish or saline lake and that the region was relatively humid during 47–43 cal kyr BP. From 43 to 27.5 cal kyr BP, the lake salinity increased and the climate began to deteriorate. From 27.5 to 11.8 cal kyr BP, aeolian activity intensified and the climate was arid. From 11.8 to 5.6 cal kyr BP, the lake salinity continuously increased, and the climate was persistently arid. After 5.6 cal kyr BP, the lake salinity dramatically increased, the lake became a salt lake, and the climate was extremely arid. In general, the climate was semihumid in mid-late MIS 3, arid in MIS 2 (27–11.7 cal kyr BP), and hyperarid in the Holocene. This climate change pattern is apparently different from that in the regions influenced by the Asian monsoon and westerlies, indicating that the enhanced Asian monsoon or westerlies were not the main forcing mechanism driving climate change in the marginal regions of the ASM domain. Enhanced ice-albedo feedback caused by the expanded Northern Hemisphere ice volume during MIS 3 would have resulted in less net incoming solar radiation and relatively low temperatures in the mid-high-latitudes. The relatively low temperatures might have weakened the evaporation capacity of Jilantai Basin and increased south-north temperature gradients, resulting in an increase in local precipitation. Therefore, the climate was semihumid in mid-late MIS 3. The lowest Northern Hemisphere summer insolation (NHSI) combined with significantly increased ice-albedo feedback associated with the largest Northern Hemisphere ice volume would have led to a remarkable reduction in temperature, resulting in the reorganization of major atmospheric and hydrological systems in the Northern Hemisphere and an arid climate in MIS 2. Subsequently, the Northern Hemisphere ice volume nearly vanished, and the rising NHSI enhanced evaporation, thereby generating a hyperarid climate in the Holocene.

Understanding long-term vegetation diversity patterns and their potential responses to climate and/or human driven processes are important for ecosystem modeling and conservation. Late-Holocene fossil pollen assemblage and associated vegetation diversity estimates provide an opportunity to explore the interactions among vegetation, climate, and human activities. A continuous 2000-year palynological record was obtained from the Beihai Wetland, southwestern China, to represent regional vegetation history, particularly the vegetation diversity changes. The results indicate that regional vegetation was dominated by deciduous broadleaved forest components (e.g. Alnus, deciduous Quercus), which showed a gradual decrease accompanied by expansion of herbaceous taxa (mainly Poaceae) after AD 800. Such progressive decline of forest was attributed to regional deforestation driven by intensified human activities, which was further confirmed by the increasing non-pollen polymorph abundance, particularly an abrupt rise after AD 1350. Vegetation diversity based on the Hill numbers ( N0, N1, and N2) showed a dramatic decline between ca. AD 200–400, which was triggered by regional fire events as shown by increased charcoal abundance from a nearby lake. The vegetation diversity reduced gradually after AD 800, especially the vegetation richness reflected by N0, revealing the transitional process from climate-driven to human-dominated vegetation changes. Minor increases of vegetation diversity occurred during Chinese dynastical transitions, probably due to reduced human activities following war-induced population crises. On the multidecadal scale, variations in vegetation diversity correlated significantly with climate fluctuations (revealed by synthesized temperature of China and stable oxygen isotope record from Dongge Cave) before AD 800, indicating a climate dominant condition. Then, the correlation between vegetation diversity and climate declined after AD 800, representing a progressive transition to human-dominant condition. In addition, the compositional turnover based on DCCA of the fossil pollen assemblage revealed a stepwise decrease, indicating reduced vegetation turnovers under anthropogenic influences.

In this paper, a new structural optimization method, “percentage structure optimization”, is presented. This method is obtained by using finite element method (FEM) to reduce a specific proportion of the stress inefficient element reduction, which is called the "structural optimization percentage index". In addition, an evaluation index of the optimized structure, “economic benefit index”, is introduced. Compared with the existing structural optimization methods, the optimization process is smoother and the results are more controllable. Moreover, the method of evaluating the optimization results through the “economic benefit index” pays more attention to the economic benefits of the project, and can achieve the balance between the minimization of material and the detention of bearing capacity to maximize the economic benefits. On the basis of the existing experiment, using ANSYS 17.0 software, two Circular Hollow Sections (CHS) X-joints are optimized by "structural optimization percentage index" of 5, 10 and 15%, and "economic benefit index" is adopted as the judgment condition of the optimization results. The results show that the method can not only guarantee the bearing capacity, but also save materials as much as possible, and verify the reliability of the new structural optimization method.

Climate changes on different timescales and their mechanisms are of great importance in arid Central Asia (ACA). However, the contribution of El Niño−Southern Oscillation (ENSO) to Holocene hydroclimate in ACA on centennial and millennial timescales is limited by records with good age control and high temporal resolution. Here, we present high-resolution X-ray fluorescence (XRF) scanning data of a sediment core from Lake Xiaolongchi in central Tianshan Mountains to reconstruct hydroclimate changes in ACA over the last 8000 years. Our construction exhibits that the climate was dry from 8000 to 5500 cal year BP and wet from 5500 to 0 cal year BP, which resembles ENSO patterns on a millennial timescale. On the centennial timescale, hydroclimate fluctuations with eight wet periods, seven dry periods, and a shift period have a significant 800-year periodicity, coincident with periodic ENSO variance. The positive relationship between 800-year band-pass filtered hydroclimate and ENSO indicates that wet (dry) climate conditions correspond to increased (reduced) ENSO activity. We propose that the spatial pattern of “wet (dry) southern China and ACA, and dry (wet) northern China” during the El Niño-like (La Niña-like) condition may exist during the Holocene on millennial to centennial timescales.

Reconstructing climate change over the last millennium is important for understanding natural climate variability and improving global climatic prediction. Precipitation variations from different records in north-central China, especially in the EASM margin area, are controversial. Here, we present a multi-proxy (grain size, pollen, TOC and TOC/TN ratio) record from Kulun-nuur Lake in east-central Inner Mongolia as an archive of moisture variations over the last millennium. Our record reveals that the Kulun-nuur Lake area is characterized by a wet Medieval Warm Period (MWP; 900–1300 AD), a dry Little Ice Age (LIA; 1300–1820 AD) and a relatively wet Current Warm Period (CWP; 1820 AD to present). In addition, within the context of an overall wet climate during the MWP, a short-term relatively dry episode occurred from 1000 to 1070 AD. The climate patterns reconstructed from Kulun-nuur Lake display good consistency with other records and models, suggesting that warm-wet/cold-dry are the main climate patterns in north-central China during the last millennium. These patterns of regional hydrological changes on multi-decadal to centennial scales may be related to solar activity and the Atlantic Multidecadal Oscillation.

The relationship between the Asian summer monsoon (ASM) and westerlies at different timescales is still under discussion. In this paper, we present Holocene precipitation records derived from loess and lake sediment in the northeastern Tibetan Plateau and reconstruct changes in the strength of the ASM during the Holocene. Compared with other Eurasian paleohydroclimatic records, we find that precipitation variations between ASM- and westerlies-dominant regions are positively correlated (anti-correlated) at millennial (sub-orbital) timescales. Based on the analysis of the TraCE-21 results, we suggest that Atlantic meridional overturning circulation may be the primary reason for this in-phase pattern at millennial timescales whereas this anti-phased pattern at sub-orbital timescales is attributed to precessional changes. Due to different response mechanisms, the relationship between the ASM and westerlies may differ significantly at different timescales, which highlights the complex dynamic characteristics of atmospheric systems in the Northern Hemisphere and the challenges for future predictions.

In this paper, we propose a new strategy for the sensitive and specific detections of dimethyl methylphosphonate (DMMP), as a simulant of nerve agent Sarin. Our silicon nanowire based sensor is modified with carboxyphenylboronic acid (CPBA) to demonstrate great efficiency. The response time is less than 100 seconds to recognize the DMMP, which is a key ability for on-site monitoring. The sensor exhibits a good reversibility during the repeated measurements between DMMP vapor and air. The sensor still performs well after being exposed in high concentration of DMMP vapor with excellent recovery for 3 times. The sensor is demonstrated to have a linear behavior in detecting DMMP within the concentration of 13~65 ppm in gaseous phase with the limit of detection (LOD) of 100 ppb. It is expected that the proposed sensor enables the testing system accurate, rapid, sensitive and reversible for on-site detection of nerve agents in the future.

Besides natural climate variations, human activities can also cause significant changes in regional vegetation composition, especially during the late Holocene period. Southwest China has experienced a long history of human activities in terms of deforestation and agricultural development. Here we present a continuous fossil pollen record covering the past 2,100 years from Beihai Wetland in western Yunnan Province, for a better understanding of regional vegetation history and potential human activities. The pollen results indicate that the forest components show decreasing trends, including Alnus dominated deciduous broadleaved forest and evergreen broadleaved forest represented by evergreen Quercus. On the other hand, herbs such as Poaceae and Artemisia expanded along with the decline of forest, especially during the period after ad 1120. The results of ordination analysis further confirm such a pattern in which the first PCA component (PC1, capturing 42.2% of total variance) represents an increasing trend, which is subsequently interpreted as an index of human activities. Our findings show broadly identical patterns to previously published sedimentary records from Yunnan as well as historical documents. The human activities increased following the expansion in regional population, in the form of deforestation and regional agricultural development. They may also have caused the expansion of herbs, especially Poaceae, which replaced forest. Therefore, as indicated by the fossil pollen record from the Beihai Wetland, human activities in southwest China increased gradually during the past 2,100 years and more rapidly after ad 1120. Results of sediment influx and grain size analyses showed generally consistent patterns with the signs of summer monsoons captured by stable oxygen isotope records from stalagmites, indicating limited influence from human activities within the wetland system compared to the regional landscape.

The irrational use of broad-spectrum antibiotics has led to increasing resistance of bacteria to antibiotics, and the emergence of the plasmid-mediated colistin resistance gene mcr-1 has led to the dilemma of infections with no available cure. Here, we have found a potential MCR-1 inhibitor for use against infections caused by MCR-1 positive resistant bacteria. A checkerboard MIC (minimum inhibitory concentration) assay, growth curve assay, kill curve assay, cytotoxicity assay, molecular dynamics simulation analysis, Western blot assay and mouse pneumonia model in vivo protection rate assay were used to evaluate the synergy effect between genistein and polymyxins. The results showed that genistein could restore the bactericidal activity against MCR-1-positive strains for which there was no antibacterial activity, and reduce the bacterial load to some extent. Genistein does not inhibit the expression of MCR-1, but inhibits the binding of MCR-1 to its substrate by binding to the amino acids of the active region of MCR-1, thereby inhibiting the biological activity of MCR-1. The in vivo results also showed that the protection rate of mice treated with the combination therapy of genistein and polymyxins increased by 20% compared to that of mice treated with polymyxins alone. Our results confirm that genistein is an inhibitor of MCR-1 and promote its potential use in combination with polymyxins to treat severe infections caused by MCR-1 positive Enterobacteriaceae.

To make a reliable reconstruction of past climate from soil-surface modern pollen, it is necessary to reduce the sources of error. In this paper, pollen percentages of the sub-continental scale modern pollen-climate dataset from China and Mongolia (with 68% soil-surface samples) are homogenized at various spatial scales. A tailored calibration-set is then applied to lake sediment-surface pollen assemblages from north-central China to evaluate their predictive power. Results indicate that spatial homogenization of modern pollen percentages can increase the proportion of inertia explained by climatic variables in CCA and improve the model performance of leave-one-out cross-validation using WA-PLS. Soil-surface pollen assemblages can thus be employed into a calibration-set for reliable climate estimation and they perform better when the calibration-set has been locally homogenized. Small-scale (e.g., radii 2, 5, or 10 km) homogenization reduces the local noise in soil-surface pollen assemblages and improves the cross-validated performance, while broader scale homogenization (more than 20 km radius) blurs the pollen-climate relationship. Lake sediment-surface pollen assemblages from close to the shore could contain pollen grains transported by rivers or from the shore vegetation and thus fail to represent regional climate well like the assemblages from the central part and deep-water area of lake.

The evolution of the Indian Summer Monsoon (ISM) has been widely investigated and traditionally interpreted as consequences of orbital forcing change and the migration of the Intertropical Convergent Zone (ITCZ). The potential influence of sea-surface temperature (SST) on ISM variation at millennial time scales has been progressively proposed in recent studies. Towards a better understanding of Holocene evolution of ISM, especially the potential response to variations in SST, a 643 cm continuous sediment sequence covering the past 11.1 ka was recovered from Beihai Wetland in western Yunnan Plateau. Fossil pollen analysis revealed that evergreen broadleaved forest dominated the regional vegetation in the early Holocene, which represented a warm and humid period associated with strong ISM. Expansions of deciduous broadleaved forest and grassland from 5.2 cal. ka BP to the present, together with the appearance of abundant plant remains, indicate the formation of the wetland system. Ordination analysis of the pollen assemblages further confirmed the abrupt vegetation turnover at ca. 5.2 cal. ka BP, which is consistent with the abrupt decline in reconstructed mean annual precipitation (Pann, from ca. 1400 to 1100 mm), and indicates an abrupt decline in the summer monsoon. We performed a climate regime shift test on various records from the ISM domain and eastern Africa and found this phenomenon as well, which could not be explained by changes in solar insolation or the migration of the ITCZ. A mid-Holocene cooling was detected from the Indian Ocean, especially a decreased SST in the tropical Indian Ocean ca. 5.5 cal. ka BP. Cooling of the tropical Indian Ocean possibly caused the abrupt retreat of the summer monsoon by restraining the duration of the monsoonal season and the convergent process, which was supported by an abrupt monsoon decline based on results from a minimal concept model.

The climatic significance of the carbonate content and composition of lake sediments remains unclear. In this study, we analyzed the glycerol dialkyl glycerol tetraethers and mineral contents of Alake Lake sediments to reconstruct temperature and moisture changes over the northeast Tibetan Plateau since 8000 cal yr BP. We identified warm (cold) and wet (dry) conditions during the Roman Warm Period and Holocene Climate Optimum (Early Neoglacial Cooling Period) accompanied by a dominance of aragonite (monohydrocalcite). Based on our results and previous laboratory experiments, we suggest that monohydrocalcite is predominantly deposited in colder, drier, and higher Mg/Ca conditions relative to that of aragonite. The carbonate mineral composition should therefore be fully considered when sediment carbonate contents are used to reconstruct paleotemperature/moisture changes.

Aim To examine the synergistic effect of calycosin combined with polymyxin B against various mcr-1-positive bacterial strains. Methods and results In this study, we found a potential inhibitor of MCR-1, calycosin, that could significantly restore the antibacterial activity of polymyxin B. The synergistic effect of calycosin combined with polymyxin B against various mcr-1-positive bacterial strains was confirmed by checkerboard minimum inhibitory concentration assays, time-kill curve assays and disk diffusion assays. The fractional inhibitory concentration indexes ranged from 0·15 ± 0·03 to 0·28 ± 0·05, and the zones of inhibition increased from 13·33 ± 0·47 to 17·67 ± 0·47 mm with the combined therapy of calycosin and polymyxin B. In addition, the combined therapy significantly reduced the number of bacteria in the medium. However, at the concentrations required for the synergistic effect with polymyxin B, calycosin alone showed no effect on bacterial growth or MCR-1 production. Calycosin treatment exhibited no cytotoxicity to HeLa cells or A549 cells at calycosin concentrations below 32 µg ml-1 . Conclusions Therefore, our results suggested that calycosin could be used as a potential MCR-1 inhibitor to restore the bactericidal effect of polymyxin B without affecting bacterial viability or existing cytotoxicity. Significance and impact of the study The synergistic effect of calycosin combined with polymyxin B against various mcr-1-positive bacterial strains paves the way for future pharmaceutical applications of calycosin in fighting mcr-1-positive bacterial infections.