Pomegranate-like porous NiCo_(2)Se_(4) spheres with N-doped carbon as advanced anode materials for Li/Na-ion batteries

Design and preparation of dual-role anode materials with extraordinary performance for rechargeable Li/Na-ion batteries (LIBs/NIBs) remains highly challenging.Herein,three-dimensional (3D) pomegranate-like porous bimetallic NiCo_(2)Se_(4) spheres with N-doped carbon (termed as NC@NiCo_(2)Se_(4)) are synthesized by solvothermal method and annealing.Microstructure investigations reveal that the NC@NiCo_(2)Se_(4) spheres include nano-sized NiCo_(2)Se_(4) particles as inner core and NiCo_(2)Se_(4) with the modification of thin-walled N-doped carbon layer as inner/outer shell.The bimetallic NC@NiCo_(2)Se_(4) spheres possess synergistic interaction of Ni/Co atoms to enhance intrinsic conductivity and electrochemical activity,unique pomegranate-like structure with an inner void space and robust shell to mitigation volume expansion,and intimate contact of N-doped carbon layer to improve interface effect and accelerate conversion kinetics.As anode materials,the NC@NiCo_(2)Se_(4) exhibits superior lithium/sodium storage performances (1401.6 and 794.8 mA h g^(-1)at current density of 0.5 and 5 A g^(-1)after 500 cycles for LIBs as well as 433.9 mA h g^(-1)at 3 A g^(-1)after 1000 cycles and a high capability of 306.6 mA h g^(-1)at 20 A g^(-1)for NIBs).This work represents an impressive strategy for future research of bimetallic selenides as anode materials for advanced high-performance LIBs/NIBs.

二氧化碳浓度增加和气候变暖导致太白山林线树木生长与氮有效性关系减弱

全球气候变暖、大气二氧化碳浓度(C_(a))升高和氮有效性正对全球森林生态系统产生深远影响,尤其是在高海拔林线地区。本研究结合树木生长指标和树轮稳定同位素指标,探讨了太白山林线树种太白红杉(Larix chinensis)对环境胁迫的生理生态响应。研究结果表明,近60年来太白红杉的生长速度显著增加,且该林线树木生长对春季温度特别敏感。太白红杉的潜在水分利用效率(iWUE)的持续上升与大气二氧化碳浓度升高和气候变暖紧密相关,共同促进了树木的生长。1851-1964年,树轮δ^(15)N随树木生长速度的加快逐渐增大;1964年之后转变为不显著的下降,打破了原有的碳-氮平衡。分析结果表明,自20世纪60年代以来气候变暖和iWUE的迅速增加已经取代氮有效性成为树木生长的主要驱动因子。随着树木持续加速生长,氮有效性在未来可能会显著下降甚至供不应求。本研究深入揭示了植物对生长环境变化响应的生理生态机制,这将提高我们预测未来高海拔地区森林生态系统演变的能力。

Gap engineering of sandwich plasmonic gap nanostructures for boosting plasmon-enhanced electrocatalysis

Plasmonic catalysis is emerging as a dynamic field in heterogeneous catalysis and holds great promise for the efficient utilization of solar energy.Central to the development of plasmonic catalysis is the design of efficient plasmonic nanocatalysts.In this report,plasmonic gap nanostructures(PGNs)on the basis of Au@poly(o-phenylenediamine)(POPD)@Pd sandwich nanostructures are synthesized as plasmonic nanocatalysts by an in-situ reduction synthetic strategy,which allows for the precise engineering of the POPD gap size between plasmonic Au and catalytic Pd components.The introduction of conducting POPD nanogap in PGNs not only effectively enhances their light harvesting capability,but also provides an effective charge transfer channel for harnessing the photogenerated hot charge carriers.In this respect,distinct gap-dependent performances in plasmon-enhanced electrocatalysis of ethanol oxidation reactions(EOR)are demonstrated with the PGN nanocatalysts and over 2.5 folds of enhancement can be achieved.A volcano plot is derived to describe the relationship between the catalytic activities and gap size of the PGN nanocatalysts,which is well explained by the interplay of their light harvesting and charge transport capabilities.These results highlight the importance of gap engineering in PGNs for plasmonic catalysis and offer the promise of developing efficient plasmonic nanocatalysts for other heterogeneous catalytic reactions.

Relative humidity reconstruction for northwestern China's Altay Mountains using tree-ring δ^(18)O

Relative humidity is an important factor in water and water vapor feedback cycles.In this study,we established a 222-year annual tree-ring δ^(18)O chronology for Siberian larch(Larix sibirica Ldb.)from the Altay Mountains in northwestern China.Climate response analyses revealed that the relative humidity was the primary factor limiting tree-ring δ^(18)O fractionation.Based on our analysis,tree-ring δ^(18)O can be used to reconstruct the July–August relative humidity based on both a reasonable mechanism of tree-ring δ^(18)O fractionation and a statistically significant regression model.We used this model to reconstruct variations in the July–August relative humidity,and the model explained 47.4% of the total variation in the measured relative humidity data from 1961 to 2011.The relative humidity in the study area increased from 1900 to the 1990s and decreased thereafter.Two regime-shift dry periods were detected during the study period(one from 1817 to 1830 and the other from 2004 to 2011).

Chemiluminescence and electrochemiluminescence applications of metal nanoclusters

Due to strong photoluminescence,extraordinary photostability,excellent biocompatibility,and good water-solubility,metal nanoclusters have attracted enormous attention since discovered.They are found to be novel fluorescence labels for biological applications and environmental monitoring.Recently the chemiluminescence(CL) or electrochemiluminescence(ECL) of metal nanoclusters has received increasing attention.This review covers recent vibrant developments in this field of the past 5 years,and highlights different functions of metal nanoclusters in various CL and ECL systems,such as luminophores,catalysts,and quenchers.Latest synthetic methods of metal nanoclusters used in CL or ECL are also summarized.Furthermore,we discuss some perspectives and critical challenges of this field in the near future.

Increased mercury pollution revealed by tree rings from the China's Tianshan Mountains

Mercury (Hg)can be transported globally by the atmospheric circulation and it accumulates and biomagnifies along food chains [1,2].Due to its threats to human health and wildlife when converted to the neurotoxin methyl mercury,variations in Hg concentration in various ecosystems were paid more attention by scientists recently.Natural processes such as geothermal activities, volcanic activities,and weathering of Hg-containing rocks,can release a mass of Hg to the environment.Anthropogenic emissions had become the main atmospheric pollution source since the Industrial Revolution.A recent study indicated that half of the Hg presented in atmosphere was sourced from human activities and about 73%total mercury was released after 1850[3].Aiming to reduce the impact of Hg to environmental and human health,UNEP (United Nations Environment Programme)passed the Minamata Convention in 2013to limit Hg emission through contro|ling technologies on air pollution.

Electrochemiluminescence Imaging Techniques for Analysis and Visualizing

Electrochemiluminescence(ECL)-based imaging analysis is a dominant method to inspect the electrode composition,to study electrochemical reaction kinetics at a microscopic level,and also a rapid emerging technology in bioanalysis with high spatiotemporal resolutions,high-throughput and visualization characteristics.In comparison with other imaging microscopes,an optical excitation is not involved in imaging,thus the approach is free from background noise resulting in a low detec-tion limit.In this review work,the principle of ECL,its unique natures compared to other luminescence techniques were briefed at first.Then after,the progress and basic principles of ECL imaging were summarized.Furthermore,recent and representative advances of ECL imaging for visualizing and sensing applications were reviewed.Finally,the perspectives in ECL imaging for further perspective were discussed.

Long-term mercury variations in tree rings of the permafrost forest,northeastern China

Permafrost is a potential mercury(Hg)pool released by thawing,which can raise the risk of Hg pollution under global warming.Tree rings are useful archives of environment-specific Hg exposure over long periods.We determined Hg concentrations in tree rings of two dominant tree species(Larix gmelinii Rupr.and Pinus sylvestris var.mongolica)at permafrost sites in northeastern China.The biweighted mean Hg concentrations ranged from 0.36 to 3.96 ng g^(-1) from 1840 to 2014.The tree-ring width had no significant influence on the Hg concentration.Larch Hg increased slightly before the 1970 s and peaked in the 1990 s.However,the pine Hg concentration increased continuously until the 1930 s,decreased rapidly until the 1970 s,then rose to a peak in the late 1980 s.The change of Hg concentrations in larch and pine revealed a time offset of 4 to 5 years,which implied possibly high mobility of Hg in pine tree rings.Higher Hg concentrations from 1920 to 1960 and subsequent decreases in isolated permafrost forests revealed the local geographical Hg cycling history.Lower Hg concentrations and faster increases in larch suggest the role of additional winter Hg loading for the evergreen pine and species-specific differences in root absorption in response to melting permafrost.Our results highlight possible geographical impacts on tree-ring Hg records,improve understanding of Hg cycles in permafrost forest,and suggest a need to sample additional species in a range of permafrost environments.

Ratiometric fluorescence detection of bleomycin based on proximity-dependent fluorescence conversion of DNA-templated silver nanoclusters

We design a ratiometric fluo rescent sensing platform for bleomycin(BLM) by using proximity-dependent DNA-templated silver nanoclusters(DNA-AgNCs) probe.This ratiometric sensing system is constructed with DNA-AgNCs as single fluorophore.The proposed strategy is based on the two following facts:(1) a covert DNA can approach and transform the DNA-AgNCs with green emission(G-DNA-AgNCs) into red emission through hybridization reaction.(2) The specific cleavage of the convert DNA by BLM in the presence of Fe(Ⅱ) inhibits the discoloration of G-DNA-AgNCs.Thus,benefiting from the specific recognition of BLM and unique properties of G-DNA-AgNCs,a hignly-sensitive ratiometric sensor for BLM has been successfully developed.The detection limit is as low as 30 pmol/L.This label-free fluorescence probe possesses advantages of convenient synthetic process and low cost.Moreover,this ratiometric method has been applied to the detection of BLM in human serum samples,illustrating a promising tool for analysis of BLM in cancer therapy.

Boric Acid-Based Dual Modulation Photoluminescent Glucose Sensor Using Thioglycolic Acid-Capped CdTe Quantum Dots

Most luminescent glucose sensors based on the interaction of glucose with organic boric acids or borates.Herein,a new luminescent glucose sensor is designed using thioglycolic acid-capped CdTe quantum dots in the presence of cheap inorganic boric acid.Both peak position and intensities change upon the addition of glucose because of the interaction of boric acid with glucose and thioglycolic acid-capped CdTe quantum dots,which enables glucose detection by either color change or intensity change.The luminescent intensities change linearly with glucose concentrations in the ranges from 0.03 to 1 mM and 1–25 mM with a detection limit of 10μM(S/N=3).Moreover,glucose concentrations can be conveniently detected by color change in the range from 1 mM–25 mM.It displays a highly selective response to glucose over other interfering but biologically important saccharides,amino acids,and common ions.Graphical Abstract A thioglycolic acid-capped CdTe QD-based sensor can detect glucose with wide linear range by change in intensity or color in the presence of cheap inorganic boric acid.

Recent advances in electrochemiluminescence imaging analysis

Electrochemiluminescence(ECL)has been widely applied in imaging owing to features that distinguish it from other microscopic techniques and electrochemical methods,including its high signal-to-noise ratio,remarkable sensitivity,wide linear range,high spatiotemporal resolution,and near-zero background light.Imaging technology based on ECL has been used in the fields of immunosensing,pathological cell detection,and drug analysis.Additionally,its simple operation and ability to detect dynamic processes and catalytic sites strengthen its potential for research on material surfaces and interfaces,in vivo biological analysis,and cell visualization.At the same time,the emergence of a variety of nanomaterials and new microscopic analysis equipment has further promoted the development of high-resolution ECL imaging technology.This paper introduces the development of ECL technology and the mechanisms of the main ECL systems.It then describes various forms of ECL imaging methods,and reviews research progress on ECL imaging technology in the fields of single-particle imaging,fingerprint structure analysis,and single-cell microscopic imaging.Finally,the authors offer their views about the prospects for ECL imaging technology.