The interaction between temperature and precipitation on the potential distribution range of Betula ermanii in the alpine treeline ecotone on the Changbai Mountain

Alpine treeline ecotones are highly sensitive to climate warming.The low temperature-determined alpine treeline is expected to shift upwards in response to global warming.However,little is known about how temperature interacts with other important factors to influence the distribution range of tree species within and beyond the alpine treeline ecotone.Hence,we used a GF-2 satellite image,along with bioclimatic and topographic variables,to develop an ensemble suitable habitat model based on the species distribution modeling algorithms in Biomod2.We investigated the distribution of suitable habitats for B.ermanii under three climate change scenarios(i.e.,low(SSP126),moderate(SSP370)and extreme(SSP585)future emission trajectories)between two consecutive time periods(i.e.,current-2055,and 2055-2085).By 2055,the potential distribution range of B.ermanii will expand under all three climate scenarios.The medium and high suitable areas will decline under SSP370 and SSP585scenarios from 2055 to 2085.Moreover,under the three climate scenarios,the uppermost altitudes of low suitable habitat will rise to 2,329 m a.s.l.,while the altitudes of medium and high suitable habitats will fall to 2,201 and2,051 m a.s.l.by 2085,respectively.Warming promotes the expansion of B.ermanii distribution range in Changbai Mountain,and this expansion will be modified by precipitation as climate warming continues.This interaction between temperature and precipitation plays a significant role in shaping the potential distribution range of B.ermanii in the alpine treeline ecotone.This study reveals the link between environmental factors,habitat distribution,and species distribution in the alpine treeline ecotone,providing valuable insights into the impacts of climate change on high-elevation vegetation,and contributing to mountain biodiversity conservation and sustainable development.

Effects of fencing on vegetation and soil restoration in a degraded alkaline grassland in northeast China

In order to restore a degraded alkaline grassland, the local government implemented a large restoration project using fences in Changling county, Jilin province, China, in 2000. Grazing was excluded from the protected area, whereas the grazed area was continuously grazed at 8.5 dry sheep equivalent（DSE）/hm2. In the current research, soil and plant samples were taken from grazed and fenced areas to examine changes in vegetation and soil properties in 2005, 2006 and 2008. Results showed that vegetation characteristics and soil properties improved significantly in the fenced area compared with the grazed area. In the protected area the vegetation cover, height and above- and belowground biomass increased significantly. Soil pH, electrical conductivity and bulk density decreased significantly, but soil organic carbon and total nitrogen concentration increased greatly in the protected area. By comparing the vegetation and soil characteristics with pre-degraded grassland, we found that vegetation can recover 6 years after fencing, and soil pH can be restored 8 years after fencing. However, the restoration of soil organic carbon, total nitrogen and total phosphorus concentrations needed 16, 30 and 19 years, respectively. It is recommended that the stocking rate should be reduced to 1/3 of the current carrying capacity, or that a grazing regime of 1-year of grazing followed by a 2-year rest is adopted to sustain the current status of vegetation and soil resources. However, if N fertilizer is applied, the rest period could be shortened, depending on the rate of application.

感染新型冠状病毒的2型糖尿病患者的临床特征和结果——一项回顾性研究

据报道,糖尿病及其相关的代谢性疾病是新型冠状病毒肺炎(coronavirus disease 2019,COVID-19)患者的主要合并症。这项临床研究旨在调查有或没有合并糖尿病的COVID-19患者的临床特征、影像学和实验室检查、并发症、治疗方法以及临床结局。这项回顾性研究纳入2020年1月12日至3月25日208例经实验室确认的COVID-19的住院患者(≥45岁)。分析病历信息包括临床特征、影像学和实验室检查、并发症、治疗和临床结果。其中,96名(46.2%)患者患有2型糖尿病。在COVID-19合并2型糖尿病患者中,高血压(58.3%vs.31.2%)、冠心病(17.1%vs.8.0%)和慢性肾脏病(6.2%vs.0%)的共存率明显高于没有2型糖尿病的COVID-19患者。COVID-19合并2型糖尿病患者的CT胸部扫描异常频率和程度显著增加,包括毛玻璃样混浊(85.6%vs.64.9%,P<0.001)和双侧斑片状阴影(76.7%vs.37.8%,P<0.001)。此外,患有糖尿病的COVID-19患者的血糖水平[7.23 mmol·L^-1(IQR:5.80~9.29)vs.5.46 mmol·L^-1(IQR:5.00-6.46)]、血液中低密度脂蛋白胆固醇(low-density lipoprotein cholesterol,LDL-C)[2.21 mmol·L^-1(IQR:1.67~2.76)vs.1.75 mmol·L^-1(IQR:1.27~2.01)]和收缩压[130 mmHg(IQR:120~142)vs.122 mmHg(IQR:110~137),P<0.001]显著高于没有糖尿病的患者(P<0.001)。2型糖尿病和其他代谢性疾病共存于COVID-19患者中,这可能会增加发病率并加重COVID-19的病情。血糖和脂质代谢的最佳管理是确保更好的临床结果的关键。对于患有糖尿病及其他基础和慢性代谢性疾病的COVID-19患者,应提高临床警惕性。

The Analysis on the Research Hotspot and Trend of Think Tanks of Chinese University Libraries

To objectively reflect the relevant situation of researches on think tank service of Chinese university libraries, this paper uses CNKI Database as the retrieval source, the bibliometric analysis method, and CiteSpace, a citation network analysis tool, to make quantitative analysis on the literature data of researches on the think tank service of university libraries;draw the knowledge map of literature authors, organization distribution, keyword co-occurrence, research hotspot distribution, etc.;objectively and comprehensively analyzes the hot topics and cutting-edge trends of researches on the think tank service of libraries, the research includes the following aspects: First, the status quo and orientation of the existing university library think tanks in China;second, it is recommended to carry out research on policy support and system guarantee for university library think tank services;third, integrate big data technology is merged into the construction of university libraries think tanks;fourth, the transformation of library and information institutions to new types of think tanks, including the transformation of knowledge services, disciplinary services, and characteristic think tanks, in order to provide reference for researches and practical work of think tank service of libraries in China.

The distribution patterns and temporal dynamics of carabid beetles(Coleoptera:Carabidae)in the forests of Jiaohe,Jilin Province,China

Carabid beetles,predatory insects,are abundant in forests and sensitive to environmental changes.The distribution patterns and diversity of carabid beetles in several natural forests were studied to provide a basis for evaluating the importance of a forest in the protection of carabid beetle diversity.Carabids were captured by pitfall traps during their seasonal activity from 2012 to 2013 in a poplar-birch forest,ash-walnut forest and broad-leaved Korean pine forest.A total of 5252 individuals,representing 21 species,were collected.Carabid abundance was highest in the broad-leaved Korean pine forest and lowest in the ash-walnut forest.Carabus billbergi Mannerheim and Pterostichus pertinax(Tschitscherine)were the dominant beetle species in each stand.Carabus canaliculatus Adams was dominant in the poplar-birch and ash-walnut forests,and Leistus niger Gebler was dominant in the ash-walnut forest.The carabids were affected differently by stand factors.C.billbergi and P.pertinax was positively correlated with mean DBH.C.canaliculatus and L.niger were not positively correlated with any stand factors.The broad-leaved Korean pine forest with greater age,large DBH and thick leaf litter fostered a high diversity of carabid species.The main yearly activity period for most carabids was during July.Different carabid species responded differently to seasonality,and the activity period of several species was relatively late(August)in the year.

Imidazole-Linked Fully Conjugated Covalent Organic Framework for High-Performance Sodium-Ion Battery

Covalent organic frameworks(COFs)have garnered increasing attention as promising electrode materials for sodium-ion batteries(SIBs)due to their ordered backbones,uniform pore sizes,and high surface areas.However,they also face challenges,including low capacity,unsatisfactory rate performance,and limited cycling stability,which pose the primary obstacles to their practical use.Herein,a pyrenoimidazole-based COF,denoted as PyIm-COF,has been synthesized as a novel electrode material for highperformance SIBs using an efficient synthetic strategy.With extended fully conjugated backbones and readily accessible redox-active sites,PyIm-COF demonstrates remarkable high-rate performance,delivering around 250 m Ah g^(−1)and excellent cycling stability,retaining 97.2%of its capacity even after 2500 cycles at 5 A g^(−1),which is higher than that of most previously reported COF-based SIBs.This work provides valuable insights into the development of nitrogen-rich conjugated COF electrode materials for rechargeable SIBs.

Highly Conductive Poly(Imide–Imine)Hybrid Vitrimer-Graphene Aerogel Composites

Comprehensive Summary,Although polyimides(PIs)have shown great potential for a broad range of applications,it remains very challenging to achieve the malleability,rehealability and recyclability for PIs and their composites targeting various applications,particularly for the rapidly emerging flexible and stretchable electronics.Herein,malleable conductive poly(imide-imine)hybrid(PIIH)vitrimer-graphene aerogel(GA)composites have been prepared,for the first time,via simple sol-gel film formation followed by heat-press.The resulting PIIH-GA composites exhibit not only the highly desired properties of thermosetting(strong mechanical strength)and thermoplastic(reprocessability)polymers,but also good conductivity enabled by the GA filler.PIIH3-GA-10(with 10 wt%GA)showed one of the highest electrical conductivities(26.7 S/m)for PI-based composites,as well as good electromagnetic interference(EMI)shielding performance.Moreover,the PIIH-GA films could maintain good performance during stretching and even after chemical recycling,which opens new opportunities for flexible and sustainable electronics development.

Recent Progress in Constructing Structurally Ordered Polymeric Architectures via Dynamic Covalent Chemistry

Although dynamic covalent chemistry(DCvC)has been widely utilized to synthesize small molecules and polymers,it remains challenging to construct highly ordered polymeric architectures via DCvC.Further exploration of novel dynamic linkages(in addition to commonly used imine and boronate ester)will expand the library of readily accessible dynamic linkages,diversify the polymeric structures,and unlock new functionality.In this mini-review,the DCvC-based synthetic strategies for enhancing the structural orders of polymeric architectures will be discussed from both thermodynamic control and kinetic control aspects.The relationship between the structure,stability,and dynamic behavior of a DCvC bond will be presented.Then recent examples of constructing polymers with DCvC and supramolecular bonding interactions,such as metal-ligand coordination,host-guest binding,and hydrogen bonding,will be reviewed to demonstrate their synergistic relationship.Furthermore,polymers featuring relatively unexplored DCvC will be highlighted to underscore how developing novel dynamic linkages and fundamental DCvC studies can broaden the scope of functional polymeric architectures.In the end,the challenges in the current field and possible future directions will also be discussed.Advancements in using these design principles will undoubtedly lead to the development of intriguing chemistries,polymeric architectures,and functionality.

Monolithic polyimine vitrimer/graphene aerogel composites

Graphene-polymer composites have attracted great attention as sensing materials due to their tailorable electrical conductivity, physicochemical properties, and sensitivity to geometric and functional changes.Herein, we report the first example of cylindrical monolithic polyimine vitrimer/graphene composites with excellent mechanical, compressive, rehealable and recyclable, and piezoresistive properties via simple infiltration of polymer monomers into the pores of graphene aerogel followed by thermal curing. The composites exhibit excellent durable compressibility(negligible reduction in the compression properties even after 3000 consecutive compression cycles), rapid recovery to the original size upon stress released,high compressive strength(up to 1.2 MPa), and high conductivity(up to 79 S/m). Excellent piezoresistive properties were observed, displaying consistent and reliable change of the electrical resistance with the compression ratio. Furthermore, rehealing with ~100% recovery of the compressive strength and electric conductivity was achieved under mild rehealing conditions, which is highly desired but has rarely been reported for electronic materials. The facile strategy for fabrication of rehealable monolithic polymer/GAs can open new possibilities for the sustainable development of composites with high electrical conductivity for various applications such as sensing, health monitoring, and movement detection.

Recent development of efficient electrocatalysts derived from porous organic polymers for oxygen reduction reaction

Porous organic polymers(POPs) have recently emerged as promising candidates for catalyzing oxygen reduction reaction(ORR).Compared to conventional Pt-based ORR catalysts, these newly developed porous materials, including both non-precious metal based catalysts and metal-free catalysts, are more sustainable and cost-effective. Their porous structures and large surface areas facilitate mass and electron transport and boost the ORR kinetics. This mini-review will give a brief summary of recent development of POPs as electrocatalysts for the ORR. Some design principles, different POP structures, key factors for their ORR catalytic performance, and outlook of POP materials will be discussed.

生物质基可锻造材料的制备和闭环循环利用

塑料废弃物的大量积累已经对生态系统造成了严重的威胁.因此,寻找和开发可以替代石油基塑料的生物质基材料成为亟待解决的问题.然而,分离生物质中各组分的成本较高,且生物质材料不具备传统塑料的加工特性,从而制约了生物质基塑料材料的开发.本文报道了一种通过直接复合未分离的生物质和动态共价聚合物高效制备生物质基塑料的方法.通过简单的热压复合生物质/动态共价聚合物混合物即可获得连续相的塑料状材料.该材料不仅具有优异的可修复、再加工和热塑形特性,而且可以完全降解和回收利用.该研究为大规模工业化生产环境友好型生物质基塑料开辟了新道路.

Spirobifluorene-Based Three-Dimensional Covalent Organic Frameworks with Rigid Topological Channels as Efficient Heterogeneous Catalyst

Although the past decade has witnessed tremendous progress in the development of covalent organic frameworks(COFs),three-dimensional(3D)COFs fabrications and characterizations are still much less studied compared with two-dimensional(2D)COFs,due to their complicated topology structures caused by interpenetration and limited choices of node-building blocks.In this work,we constructed a novel 3D COF(SP-3D-COF-BPY)successfully using orthogonal dual-planar spirobifluorene and bipyridine as building blocks.Also,we demonstrated the application of 3D COF-supported Pd(II)catalyst in heterogeneous catalysis.A sevenfold interpenetrated dia structure was revealed for SP-3DCOF-BPY by powder X-ray diffraction(PXRD)in conjunction with structural simulation and Pawley refinement.The bipyridine-linked frameworks bear one-dimensional(1D)unobstructed rigid channels and offer a high density of discrete coordination sites for chelating Pd(II)species.Very high loading of Pd(II)(∼15 wt%)was achieved in the asymmetric(as)-prepared Pd(II)@3D-COF-BYP.The generated highly ordered porous channels and easily accessible catalytic sites,such as COF-supported Pd(II)complex,serves as a highly active and stable microporous heterogeneous catalyst in Suzuki–Miyaura coupling reactions.The observed catalytic efficiency was high and the catalyst could be conveniently reused multiple times without any noticeable decay in catalytic performance.

Porous Pyrene Organic Cage with Unusual Absorption Bathochromic-Shift Enables Visible Light Photocatalysis

We have constructed a novel porous pyrene-based organic cage,PyTC1,through the condensation reaction of cyclohexanediamine with 5,5′-(pyrene-1,6-diyl)diisophthalaldehyde.Single-crystal X-ray diffraction analysis reveals the effective intercage C–H...πinteraction between cyclohexanediimine and pyrene segments.Such a soft intercage C–H...πinteraction,rather than a classic J-aggregate with slippedπ–π-stacking configuration,induced an unusual bathochromic shift of pyrene-based chromophore absorption from an ultraviolet region of PyTC1 in solution to the visible light region of PyTC1 in solid-state.

Helical Covalent Polymers with Unidirectional Ion Channels as Single Lithium-Ion Conducting Electrolytes

Single-ion conducting polymer electrolytes have attracted great attention as safe alternatives to liquid electrolytes in high energy density lithium-ion batteries.Herein,we report the first example of a crystalline anionic helical polymer as a single lithium-ion conducting solid polymer electrolyte(SPE).Single-crystal X-ray analysis shows that the polymer folds into densely packed double helices,with bundles of unidirectional negatively charged channels formed that can facilitate lithium-ion transportation.

Highly stable dioxin-linked metallophthalocyanine covalent organic frameworks

We report a series of highly stable metallophthalocyanine-based covalent organic frameworks(MPc-dxCOFs) linked by robust 1,4-dioxin bonds constructed through nucleophilic aromatic substitution(SNAr)reaction. The chemical structures and crystallinity of the COFs largely remain unchanged even after treating with boiling water(90°C), concentrated acids(12 mol/L HCl) or bases(12 mol/L Na OH), oxidizing(30% H_(2)O_(2)) or reducing agents(1 mol/L NaBH;) for three days due to their stable M-Pc building blocks and resilient dioxin linkers. With metallated phthalocyanine active sites regularly arranged in the stable framework structures, MPc-dx-COFs can be directly used as efficient electrocatalysts for the oxygen reduction reaction(ORR) without pyrolysis treatment that has commonly been used in previous studies.