喀斯特原生天坑垂直梯度上植物多样性特征——以云南沾益天坑为例

规模宏大的地表负地形——喀斯特天坑具有巨大的容积和陡峭圈闭的岩壁,在坑底形成异于坑外的独特微生境,是研究物种组成和多样性的理想场所,但目前鲜少对喀斯特天坑植物群落的生态过程及其空间变化特征进行探讨。本研究以云南沾益大毛寺原生天坑植物群落为研究对象,通过游动分割窗技术以及边缘效应值、边缘效应强度和β多样性指数的计算,对原生天坑\"坑边缘—坑壁—坑底\"的生态交错带进行定量判定,探讨垂直环境梯度上植物群落物种多样性变化特征及天坑内外物种多样性边缘效应特征。研究结果表明,原生天坑\"坑边缘—坑壁—坑底\"垂直梯度上的生态交错带出现在坑壁中域位置,宽度大约为40 m,是连接天坑内外生态系统的一个特殊生态过渡带;天坑内外植物群落在坑壁出现\"断裂\",存在不同于一般生态交错带的\"边缘负效应\";基于β多样性指数,垂直环境梯度上植物物种更替率总体呈上升趋势,坑底与坑边缘的植物群落物种组成存在较大差异,坑底拥有更高的物种丰富度和多样性,具有重要的物种多样性保护库价值

喀斯特原生天坑植物群落空间格局特征——以云南沾益天坑为例

以云南沾益大毛寺原生天坑为例,获取坑内植物群落林木个体相对位置信息,进行角尺度、混交度、林层指数等林木空间结构参数与坑底植物群落空间格局分析,并运用点格局分析方法进行单个种群的空间分布特征以及不同种群间的空间关联性分析.结果表明:大毛寺原生天坑坑底植物群落在空间分布上呈现随机分布,林木物种呈中度混交,林木垂直分层虽较简单,但结构稳定,具有发育成熟的顶极森林群落的空间分布特征;坑底植物群落的种群主要呈聚集分布,种群间呈负关联,且处于同一垂直层次上种群间空间负相关性更强,垂直层次相差越大,空间竞争性越小,而随着空间范围的增大,空间负关联越弱;坑内生态系统具有较高的稳定性,是难得的物种自然栖息地和生态避难所,独特生境中形成的稳定植物群落结构在喀斯特地区生态恢复研究中具有重要的借鉴意义和导向作用.国家重点研发计划项目(2016YFC0502900)资助~

海洋现场叶绿素传感器的校准方法初探

采用单一藻种培养液校准海水现场叶绿素传感器,讨论了校准方法及传感器应用在海洋调查中的可行性,结果发现,利用威氏海链藻(Thalassiosira weissflogii)的培养液校准叶绿素传感器,叶绿素浓度与荧光信号线性关系良好,相关系数R2均大于0.995,每次实验的校准斜率误差均小于5%,表明利用藻液校准叶绿素传感器是可行的,具有可重复性。然后利用传感器与荧光分光光度法测量同一系列藻液,t检验法分析表明当叶绿素浓度大于5μg/L时,两种方法无显著差异;当浓度小于5μg/L时存在显著差异,传感器测量结果偏大;可能是高温、光照等影响荧光分光光度法测量结果。就荧光分光光度法而言,叶绿素传感器可以比较准确地评价水体的叶绿素浓度,不仅可以为浮游植物动力学提供依据,还可以为赤潮预警等提供数据支撑

粗糙铂电极上甲酸吸附氧化的电化学原位表面增强拉曼光谱研究

采用循环伏安法和电化学原位表面增强拉曼光谱 (SERS)技术研究甲酸的解离吸附与氧化行为 .首次报道了甲酸吸附、解离和氧化的电化学原位SERS谱 ,发现甲酸在粗糙铂电极上能自发解离吸附 ;首次成功地获得了粗糙铂电极上甲酸吸附解离的强吸附中间体CO和活性中间体COOH的表面增强拉曼光谱 ,同时首次检测到甲酸氧化最终产物CO2 的拉曼光谱信号 ,从分子水平证实甲酸解离吸附反应的双途径机理

Preparation of nano-structured platinum electrode surfaces by electrochemical methods and its properties

The nano-sized constant potential roughened platinum (CPRPt) and constant current roughened platinum (CCRPt) electrode-surfaces have been prepared successfully by oxidation-reduction-cycle method. Many regularly shaped triangle-cones of the size of 10 similar to 30 nm were observed on the CPRPt electrode surface by the scan electron microscopy (SEM) technology. The electro-oxidation of methanol on the nano-CPRPt and the CCRPt electrode-surfaces was used to investigate the performances with the results of the peak current density 1.35 and 2.50 times greater than those of smooth Pt respectively. The in situ Raman spectra of these two kinds of electrode-surfaces indicated their high surface enhanced Raman spectrum (SERS) effects for pyridine adsorption. The CPRPt electrode surface has extraordinarily enhanced effect for adsorption-dissociation of small organic molecules. The mechanism of SERS on these platinum electrode-surfaces has been also discussed

In-situ SERS study on the electro-oxidation with HCOOH on a roughened platinum electrode

The dissociative adsorption and oxidation behavior of HCOOH on Pt was investigated by cyclic voltammogram (CV) and in-situ surface enhanced Raman spectroscopy (SERS) techniques. The in-stiu SERS of HCOOH adsorption, dissociation and oxidation on rough Pt is reported. It is found that HCOOH can spontaneously dissociate. The surface Raman spectra of CO, the strongly adsorbed intermediate and COOH, the weakly adsorbed intermediate of the dissociative adsorption of HCOOH were successfully obtained for the first time. At the same time, the Raman spectra of the finally oxidized product CO2 of HCOOH was also firstly detected. The dual path reaction mechanism for the oxidation of HCOOH was confirmed at molecular level

Synthesis of magnetic, fluorescent and mesoporous core-shell-structured nanoparticles for imaging, targeting and photodynamic therapy

通讯作者地址: Chen, XL (通讯作者),Xiamen Univ, Coll Chem & Chem Engn, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R ChinaA synthetic method to prepare novel multifunctional core-shell-structured mesoporous silica nanoparticles for simultaneous magnetic resonance (MR) and fluorescence imaging, cell targeting and photosensitization treatment has been developed. Superparamagnetic magnetite nanoparticles and fluorescent dyes are co-encapsulated inside nonporous silica nanoparticles as the core to provide dual-imaging capabilities (MR and optical). The photosensitizer molecules, tetra-substituted carboxyl aluminum phthalocyanine (AlC(4)Pc), are covalently linked to the mesoporous silica shell and exhibit excellent photo-oxidation efficiency. The surface modification of the core-shell silica nanoparticles with folic acid enhances the delivery of photosensitizers to the targeting cancer cells that overexpress the folate receptor, and thereby decreases their toxicity to the surrounding normal tissues. These unique advantages make the prepared multifunctional core-shell silica nanoparticles promising for cancer diagnosis and therapy.NSFC21021061,20925103,20871100,Fok Ying Tung Education Foundation 121011 NSF of Fujian Province 2009J06005 Fundamental Research Funds for the Central Universities 2010121015 Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministr

现场拉曼光谱研究多种铂氧化物还原过程及其对甲醇氧化的影响

采用原位拉曼光谱技术研究方波电位循环氧化还原 (ORC)过程中产生的铂氧化物的还原过程 ,其中过氧化物和超氧化物消失的电位在 0 2V左右 ,晶格氧化物和氧化铂则分别消失在 0V和 -0 2 5V左右。我们还初步探讨了不同还原电位下形成的铂电极表面纳米微粒对甲醇电催化活性的影

Jumping Design and Dynamics Analysis on a Hopping Frog Robot

当前,弹跳机器人有着广泛的应用前景,提高其弹跳性能是一个值得探讨的课题。设计并分析了一种仿青蛙跳跃的弹跳腿。将其简化为双质量弹簧模型,得出了其跳起的必要条件及在空中运动状态的动力学方程。仿真结果表明,该弹跳腿的设计是可行的。Now,hopping robot will be used more and more and how to improve its capability of jumping is a valuable research.In virtue of analyzing frog's jumping,this paper designs a hopping leg,then abstracts the leg and find a system model composed by two mass bodies and a spring,finds the qualification and the equation of jumping.The result shows that the designed leg is feasible

Jumping Machine Design and Dynamics Analysis of Hopping Robots

为了阐明弹跳机器人弹跳运动,包括弹跳的必要条件、弹跳高度等,基于仿生学原理、通过模仿青蛙的跳跃,本文设计并制作了一种结构简单、新颖的弹跳机构.通过将其简化成双质量弹簧模型,得出其能实现跳跃时弹簧所需储存的最小能量.在此基础上进一步推导出双质量弹簧系统在空中阶段质心和底座重心运动的规律.仿真结果表明,弹跳腿所能储存的能量超过其跳起的必要条件,从而进一步说明该设计是可行的.In order to describe the robot′s jump movement,including the necessary jumping conditions and the height of jump,this article describes a design of a hopping machine based on the principles of bionics which can jump like a frog.Its structure is simple and novel.By the geminate mass spring model from the hopping machine,the least energy for the hopping machine to jump can be calculated.Based on this result,the moving rules of the model′s jump in sky are acquired,such as the rules of centroids of the geminate mass spring model and its pedestal.The result of emulational experiment illustrates that the energy contained by the hopping legs surpasses the necessary needed,so this means the design is feasible