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Critical minimum temperature limits xylogenesis and maintains treelines on the southeastern Tibetan Plateau

Science Bulletin 2017年第11期62卷 804-812页

作者： xiaoxia li Eryuan liang Jozica Gricar Sergio Rossi Katarina Cufar Aaron M. Ellison Key Laboratory of Alpine Ecology and Biodiversity Key Laboratory of Tibetan Environment Changes and Land Surface Processes Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 100101 China CAS Center for Excellence in Tibetan Plateau Earth Sciences Beijing 100101 China Sloven ian Forestry Institute Department of Yield and Silviculture Vecna pot 2 S1-1000 Ljubljana Slovenia University of Quebec in Chicoutimi Departement des Sciences Fondamentales 555 Boulevard de l'Universite Chicoutimi (QC) G7H2B1 Canada Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems Guangdong Provincial Key Laboratory of Applied Botany South China Botanical Garden Chinese Academy of Sciences Guangzhou 510650 China University of Ljubljana Biotechnical Faculty Department of Wood Science and Technology Jamnikarjeva 101 S1-1000 Ljubljana Slovenia Harvard Forest Harvard University 324 North Main St. Petersham MA 01366 USA

Physiological and ecological mechanisms that define treelines are still debated. It has been suggested that the absence of trees above the treeline is caused by low temperatures that limit growth. Thus, we hypothesized that there is a critical minimum temperature （CTmin） preventing xylogenesis at treeline. We tested this hypothesis by examining weekly xylogenesis across three and four growing seasons in two natural Smith fir （Abies georgei var. srnithii） treeline sites on the southeastern Tibetan Plateau. Despite differences in the timing of cell differentiation among years, minimum air temperature was the dominant climatic variable associated with xylem growth; the critical minimum temperature （CTmin） for the onset and end of xylogenesis occurred at 0.7 ±0.4 ℃. A process-based modelling chronology of tree-ring formation using this CTmin was consistent with actual tree-ring data. This extremely low CTmin permits Smith fir growing at treeline to complete annual xylem production and maturation and provides both support and a mechanism for treeline formation.

关键词： Cambial activity Critical minimum temperature Timberline Xylem Vaganov-Shashldn model

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Changes in retinal and choroidal morphology after cerebrospinal fluid pressure reduction: a Beijing iCOP study

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Science China(life Sciences) 2019年第2期62卷 268-271页

作者： Lu liu xiaoxia li Hanspeter E Killer Kai Cao Jing li Ningli Wang Beijing Tongren Eye Center Beijing Tongren Hospital Capital Medical University Beijing Ophthalmology and Visual Sciences Key Laboratory Beijing institute of Ophthalmology Department of Ophthalmology Kantonsspital Aarau Eye Institute University of Basel

Dear Editor,Glaucoma is a multifunctional neurodegenerative disease and is the leading cause of irreversible blindness. It is characterized by progressive loss of retinal ganglion cells and their axons leading to visu... 详细信息

关键词： CSF a Beijing iCOP study IOP Figure

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Unlocking single-atom catalysts via amorphous substrates

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Nano Research 2024年第5期17卷 3533-3546页

作者： Bohua Sun Mingyuan Xu xiaoxia li Baohong Zhang Rui Hao Xiaoyu Fan Binbin Jia Dingshun She School of Engineering and Technology China University of Geosciences(Beijing)Beijing 100083China Zhengzhou Institute China University of Geosciences(Beijing)Zhengzhou 451283China College of Materials and Chemical Engineering Key Laboratory of Inorganic Nonmetallic Crystalline and Energy Conversion MaterialsChina Three Gorges UniversityYichang 443002China School of Chemistry Beihang UniversityBeijing 100191China Chinese Academy of Sciences(CAS)Key Laboratory of Nanosystem and Hierarchy Fabrication CAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyBeijing 100190China National Engineering Research Center of Nonferrous Metals Materials and Products for New EnergyChina GRINM Group Co.Ltd.Beijing 100088China

Single-atom catalysts(SACs)reveal great potential for application in catalysis due to their fully exposed active *** general,single atoms(SAs)and the coordination substrates need to have strong interactions or charge transfer to ensure the atomic dispersion,which requires the selection of a suitable substrate to stabilize the target *** studies have demonstrated that amorphous materials with abundant defects and coordinatively unsaturated sites can be used as substrates for more efficient capturing SAs,further enhancing the catalytic *** this review,we discuss recent research progress of SAs loaded on amorphous substrates for enhanced catalytic ***,we summarize the commonly used amorphous substrates for stabilizing ***,we present several advanced applications of amorphous SACs in the field of catalysis,including electrocatalysis and *** then,we also clarify the synergistic mechanism between SAs and amorphous substrate on catalytic ***,we summarize the challenges with our personal views and provide a critical outlook on how amorphous SACs continue to evolve.

关键词： single-atoms amorphous substrate synthetic strategy catalysis

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QDB-Tensors and SQDB-Tensors

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Journal of Mathematical Research with Applications 2019年第2期39卷 132-140页

作者： xiaoxia li Aiquan JIAO Junyuan YANG School of Mathematics and Information Technology Yuncheng University School of Mathematical and Physical Science and Engineering Hebei University of Engineering Complex Systems Research Center Shanxi University

In this paper, we propose four new classes of structured tensors: QDB(QDB0)-tensors and SQDB(SQDB0)-tensors, and prove that even order symmetric QDB-tensors and SQDB-tensors are positive definite, even order symmetric... 详细信息

关键词： B-tensors QDB-tensors SQDB-tensors positive definite P-tensors

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Temperature variability in northern Iran during the past 700 years

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Science Bulletin 2018年第8期63卷 462-464页

作者： Vilma Bayramzadeh Haifeng Zhu Xiaoming Lu Pedram Attarod Hui Zhang xiaoxia li Fayaz Asad Eryuan Hang Key Laboratory of Alpine Ecology and Biodiversity Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 100101 China Department of Wood Sciences Faculty of Agricultare and Natural Resources Karaj Branch Islamic Azad University Karaj *** Iron Department of Forestry Forest Economics Faculty of Natural Resources University of Tehran Karaj *** Iran CAS Centre for Excellence in Tibetan Plateau Earth Sciences Beijing 100101 China Department of Botany Bacha Khan University Charsadda Khyber PakhtunKhwa 24420 Pakistan

Warming is significantly affecting ecosystems in dry-warm areas,such as the Middle East[1],but long-term climatic records are often scarce in these *** important proxy source of climate data is tree rings,which have contributed to understanding climate changes over the past millennium[1].Under the PAGES2K framework[2],a tree-ring network of the Eurasian continent

关键词：温度记录可变性伊朗气候数据生态系统温暖中东上下文

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Electrochemical properties of spinel compound liNi_(0.5)Mn_(1.2)Ti_(0.3)O_4 as cathode materials for lithium ion batteries

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Rare Metals 2010年第6期29卷 572-575页

作者： liU Guoqiang,GUO Qingshan,li xiaoxia,and WU Qiuyang School of Materials and Metallurgy,Northeastern University,Shenyang 110004,China School of Materials and Metallurgy Northeastern University Shenyang China

The electrochemical properties of spinel compound liNi0.5Mn1.2Ti0.3O4 were investigated in this *** chemicals liAc·2H2O,Mn（Ac）2·2H2O,Ni（Ac）2·4H2O,and Ti（OCH3）4 were used to synthesize liNi0.5Mn1.2Ti0.3O4 by a simple sol-gel *** discharge capacity of the sample reached 134 mAh/g at a current rate of *** first and fifth cycle voltammogram almost overlapped,which showed that the prepared sample liNi0.5Mn1.2Ti0.3O4 had excellent good cycle *** were two oxidation peaks at 4.21 V and 4.86 V,and two reduction peaks at 4.55 V and 3.88 V in the cycle voltammogram,*** electrochemical impedance spectroscopy and its fitted result,the lithium ion diffusion coefficient was measured to be approximately 7.76 × 10？11 cm2/s.

关键词： lithium batteries cathode materials sol-gel process electrochemical properties

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Cleavable bimetallic-organic polymers for ROS mediated cascaded cancer therapy under the guidance of MRI through tumor hypoxia relief strategy

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Science China Chemistry 2020年第7期63卷 936-945页

作者： Haozhe He lihua Du Min Tan Yali Chen liejing Lu Yongcheng An Yong Wang xiaoxia li Bo li Jun Shen Jun Wu Xintao Shuai PCFM Lab of Ministry of Education School of Materials Science and EngineeringSun Yat-Sen UniversityGuangzhou 510260China Department of Radiology Sun Yat-Sen Memorial HospitalSun Yat-Sen UniversityGuangzhou 510260China University of Laboratory of Interventional Radiology Department of Minimally Invasive Interventional Radiologyand Department of Radiologythe Second Affiliated Hospital of Guangzhou Medical UniversityGuangzhou 510260China School of Biomedical Engineering State Key Laboratory of Oncology in South ChinaSun Yat-sen UniversityGuangzhou 510260China

Despite recent advances in tumor treatment, reactive oxygen species(ROS)-mediated therapy, such as photodynamic therapy(PDT) and chemical dynamic therapy(CDT), remains challenging mainly due to hypoxia in tumor microenviroment. Relieving the hypoxia of tumor tissue has been considered as an attractive strategy for enhancing efficacy of ROS-based cancer ***, one cascaded platform was developed to overcome tumor hypoxia and synergistically enhance the effect of ROSmediated therapy. This platform is based on cleavable bimetallic metal organic polymers(DOX@Fe/Mn-THPPTK-PEG). As an efficient Fenton-like material, it could not only produce cytotoxic ·OH by catalyzing the decomposition of intracellular H2O2, but also generate O2 to alleviate tumor hypoxia. In addition, the DOX-loaded metal organic polymers(MOPs could be disrupted after being exposed to laser irradiation or/and treated with H2O2, and then release the DOX for chemotherapy. Overall, 3 therapies(hypoxia-relieved PDT, photo-enhanced CDT, and ROS-mediated chemotherapy) could be achieved simultaneously by such a smart platform. Furthermore, T1-weighted MRI imaging ability of the MOPs could be greatly improved under H2O2 ***, total four robust functions were realized in a simple platform. These findings demonstrate great clinical potentials of the MOPs for cancer theranostics.

关键词： reactive oxygen species photodynamic therapy chemodynamic therapy ROS sensitive drug releases MRI imaging

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TGF-β regulation of microRNA miR-497-5p and ocular lens epithelial cell mesenchymal transition

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Science China(life Sciences) 2020年第12期63卷 1928-1937页

作者： Jinda Wang Jingshang Zhang Ying Xiong Jing li xiaoxia li Jing Zhao Guyu Zhu Hailong He Yusufu Mayinuer Xiuhua Wan Beijing Institute of Ophthalmology Beijing Tongren Eye CenterBeijing Tongren Hospital of Capital Medical UniversityBeijing Key Laboratory of Ophthalmology&Visual SciencesBeijing 100005China Beijing Tongren Eye Center Beijing Tongren Hospital of Capital Medical UniversityBeijing Key Laboratory of Ophthalmology and Visual SciencesBeijing 100005China

The purpose of this study was to investigate the role of a human lens microRNA(miR-497-5p) in regulating epithelialmesenchymal transition(EMT) under the control of transforming growth factor beta(TGF-β). A microRNA array was used to evaluate the microRNA profiles of untreated and TGF-β-treated human lens epithelial cells in culture. This showed that TGF-βtreatment led to the upregulation of 96 microRNAs and downregulation of 39 microRNAs. Thirteen microRNAs were predicted to be involved in the pathogenesis of posterior capsule opacification(PCO). Meanwhile, overexpression of miR-497-5p suppressed cell proliferation and EMT 48 h post-transfection, and inhibition of miR-497-5p accelerated cell proliferation and *** with TGF-β inhibited the expression of miR-497-5p, but not cell proliferation. miR-497-5p was also found to regulate the level of CCNE1 and FGF7, which are reported to be actively involved in EMT. CCNE1 and FGF7 were bona fide targets of miR-497-5p. The results suggest that miR-497-5p participates in the direct regulation of lens epithelial cell EMTand is regulated by TGF-β. miR-497-5p may be a novel target for PCO therapy.

关键词： microRNA transforming growth factor beta(TGF-β) lens epithelial cells posterior capsule opacification

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Variation characteristics and prediction of pollutant concentration during winter in Lanzhou New District, China

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Research in Cold and Arid Regions 2020年第5期12卷 317-328页

作者： DongYu Jia xiaoxia li XiaoQing Gao liWei Yang College of Geography and Environmental Engineering Lanzhou City UniversityLanzhouGansu 730070China Northwest Regional Climate Center/Key Laboratory of Arid Climatic Change and Reducing Disaster of Gansu Province/Key Open Laboratory of Arid Climatic Change and Disaster of China Meteorological Administration/Institute of Arid Meteorology LanzhouGansu 730020China Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions/Northwest Institute of Eco-Environment and Resources Chinese Academy of SciencesLanzhouGansu 730000China

PM2.5 and PM10 were the main air pollutants during winter in Lanzhou New District,*** this paper,WRF model output combined with hourly monitoring data of pollutant concentration was used to analyze characteristics of the concentration change and to study the relationship between meteorological elements and PM10/PM2.5 in Lanzhou New District in January,***,the concentration changes of PM2.5 and PM10 were predicted by wavelet analysis combined with BP neural *** results show that:(1)Due to the cold front process in winter,PM2.5 was negatively correlated with the water vapor mixing ***10 was positively correlated with air temperature and negatively correlated with air pressure.(2)There was an inversion layer in the atmosphere near the high value day of PM2.5 and PM10,the surface was controlled by low pressure,low wind speed,and the situation of low value day of PM2.5 was the *** the day of high value of PM10,the air temperature below 600 hPa was higher,and the wind speed near the surface was also higher.(3)Wavelet analysis combined with BP(Back Propagation)neural network had a good prediction effect on PM2.5,which could basically reflect the hourly change of PM2.5 ***,the simulation effect of PM10 was poor,and the input parameters of surrounding pollutants should be added to improve the prediction effect.

关键词： PM2.5 PM10 WRF Wavelet neural network Lanzhou New District

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Mesenchymal stem cell-derived small extracellular vesicles mitigate oxidative stress-induced senescence in endothelial cells via regulation of miR-146a/Src

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Signal Transduction and Targeted Therapy 2021年第11期6卷 3318-3332页

作者： Xian Xiao Meiqian Xu Hongliang Yu liping Wang xiaoxia li Janusz Rak Shihua Wang Robert Chunhua Zhao Institute of Basic Medical Sciences Chinese Academy of Medical Sciences School of Basic Medicine Peking Union Medical CollegeBeijingChina Department of Genetics and Cell Biology Basic medical collegeQingdao University308 Ningxia Road266071QingdaoChina Research Institute of the McGill University Health Centre Glen SiteMcGill UniversityMontrealQCH4A 3J1Canada Department of Cell Biology School of Life SciencesShanghai University200444ShanghaiChina

Senescent endothelial cells (ECs) could impair the integrity of the blood vessel endothelium, leading to vascular aging and a series of diseases, such as atherosclerosis, diabetes. Preventing or mitigating EC senescence might serve as a promising therapeutic paradigm for these diseases. Recent studies showed that small extracellular vesicles (sEV) have the potential to transfer bioactive molecules into recipient cells and induce phenotypic changes. Since mesenchymal stem cells (MSCs) have long been postulated as an important source cell in regenerative medicine, herein we investigated the role and mechanism of MSC-derived sEV (MSC-sEV) on EC senescence. In vitro results showed that MSC-sEV reduced senescent biomarkers, decreased senescence-associated secretory phenotype (SASP), rescued angiogenesis, migration and other dysfunctions in senescent EC induced by oxidative stress. In the In vivo natural aging and type-2 diabetes mouse wound-healing models (both of which have senescent ECs), MSC-sEV promoted wound closure and new blood vessel formation. Mechanically, miRNA microarray showed that miR-146a was highly expressed in MSC-sEV and also upregulated in EC after MSC-sEV treatment. miR-146a inhibitors abolished the stimulatory effects of MSC-sEV on senescence. Moreover, we found miR-146a could suppress Src phosphorylation and downstream targets VE-cadherin and Caveolin-1. Collectively, our data indicate that MSC-sEV mitigated endothelial cell senescence and stimulate angiogenesis through miR-146a/Src.

关键词： miR wound healing

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