温带荒漠中温度和土壤水分对土壤呼吸的影响

荒漠对气候变化具有高度敏感性,深刻认识和量化非生物因子对荒漠生态系统土壤呼吸的影响具有重要意义。采用自动CO2通量系统(Li-8100)监测了梭梭(Haloxylon ammodendron)、假木贼(Anabasis aphylla)和盐穗木(Halostachys caspica)群落生长季土壤呼吸及温度、土壤含水量等,深入分析了水热因子对土壤呼吸的影响。土壤呼吸具有不对称的日格局,最小值出现在8:00,最大值在12:00～14:00。土壤呼吸的季节格局与气温变化基本同步,最小值在生长季末期(10月),最大值在生长季中期(6～7月)。梭梭、假木贼和盐穗木群落生长季平均土壤呼吸速率分别为0.76、0.52和0.46μmol CO2·m-2·s-1。气温对假木贼(51%)和盐穗木群落(65%)土壤呼吸季节变化的解释率高于梭梭(35%)。梭梭、假木贼和盐穗木群落土壤呼吸温度敏感性(Q10)逐渐增大,基础呼吸速率(R10)逐渐减小。剔除温度影响后,梭梭、假木贼群落土壤呼吸与土壤含水量呈显著的幂二次方函数关系,盐穗木群落两者关系却明显减弱,未达到显著水平。气温、土壤含水量的二元方程均能解释群落土壤呼吸大部分的时间变异:梭梭群落71%～93%、假木贼群落79%～82%、盐穗木群落70%～80%。人工模拟降水后土壤呼吸速率表现出降水后10min减小、180min时明显增加、达到最大值后再次衰减的现象。5和2.5mm降水处理下的土壤呼吸速率最大值和其后的递减值高于对照处理,土壤呼吸增加、达到峰值和其后递减过程与5cm土壤温度变化基本同步

便携式拉曼光谱仪快速检测唾液中盐酸吡格列酮的含量

人体唾液与血液中的相应成分有着密切关系。利用唾液代替血液进行检测,可极大地缩短分析时间、减少检测限制、降低安全隐患等,因此在临床医学、毒品管控等方面均有重要意义。发展了便携式拉曼光谱仪利用表面增强拉曼光谱技术快速定量检测唾液中盐酸吡格列酮（口服降血糖药物）含量的方法。借助纳米金溶胶的表面增强拉曼散射效应,在激发光源波长为785 nm时,可以得到低浓度盐酸吡格列酮的高质量拉曼光谱图。同时,不同浓度盐酸吡格列酮表面增强拉曼光谱分析结果表明,该方法还可直接用于唾液中盐酸吡格列酮的定量检测。盐酸吡格列酮含量与其特征峰强度线性相关,相关系数为0. 992 3,且最低检测浓度达10μg·L-1。国家自然科学基金项目(21522508);;深圳市科技计划基础研究(自由探索)项目(JCYJ20170306140934218)资

中国南方地区罗非鱼无乳链球菌的分子流行病学研究

从广东省以及海南省等地区养殖的患病罗非鱼体内分离、收集到多株致病菌,经生化分析和分子生物学鉴定,均为无乳链球菌。对这些菌株分别进行了耐药谱测定、分子分型试验以及分子血清型分析。药敏试验结果表明,2007—2010年分离到的无乳链球菌耐药谱基本相似;多位点可变数目串联重复序列分析(MLVA)试验中,选择5个高变异指数的可变数目重复位点(VNTR)进行分子分型,结果表明,所有鱼源无乳链球菌菌株为同一MLVA型,而作为对照的牛源无乳链球菌则明显不同;为了对这些菌株进一步分型,分别进行了分子血清型和表面蛋白抗原基因的检测,结果表明,鱼源无乳链球菌的分子血清型均为Ⅰa型,表面蛋白抗原均为alpha-C蛋白。这进一步说明了不同年份和不同地区的鱼源无乳链球菌在基因水平上为同一分子类型,具有相同的起源或传染源。同时也说明,我国南方地区罗非鱼无乳链球菌在这几年中未发生明显的遗传变异。这些结果为罗非鱼无乳链球菌病疫苗研制,疫病监测及药物防治的研究提供理论依据

A Self-assembly Route to Porous Polyaniline/Reduced Graphene Oxide Composite Materials with Molecular-level Uniformity for High-performance Supercapacitors

PANI具有赝电容高、稳定性好和掺杂/去掺杂反应可逆等优点，而RGO则能提供高导电和大比表面积。PANI与RGO的复合能将两种材料的优势进行互补产生协同作用。而传统的PANI/RGO电极材料的制备通常聚焦于苯胺在还原RGO上的原位聚合，其不足之处在于难以精确控制PANI组分的形貌和分布来优化材料电子转移和电解质的扩散。白华课题组巧妙利用了PANI的溶解性，设计了溶液中的自组装方法以制备PANI/RGO复合材料。白华课题组在聚苯胺/还原氧化石墨烯（PANI/RGO）电极材料研究方面取得新进展。该课题组提出了一种简便可控的自组装方法，成功制备了分子水平均匀的PANI/RGO复合凝胶（PGG）。该方法大幅度提高了电极材料的比电容和倍率性能。此外，本工作还证实了GO是一种有效的二维表面活性剂，可与其他分子形成复合物，并使它们进入复杂的自组装过程。该方法还可以指导我们设计具有各种组成，结构和其他功能的基于RGO的复合材料。 该论文的第一作者为我院已毕业2016届硕士生巫继锋，我院张勤娥（2015级硕士生）、王菁菁（2014级博士生）、黄晓萍（2016级硕士生）参与了论文的部分工作。【Abstract】Polyaniline/graphene composites constitute an important class of electrode materials for supercapacitors. In this paper, we designed a new self-assembly method for preparing polyaniline/reduced graphene oxide three-dimensional porous composite gels with molecular-level uniformity even at a very high PANI content (>80%). The method involves two successive self-assembly processes, namely, two-dimensional assembly of polyaniline on graphene oxide sheets in a water/N-methyl-2-pyrrolidone blend solvent, and three-dimensional reduction-assembly of the obtained polyaniline/graphene oxide composite sheets. The prepared polyaniline/reduced graphene oxide composite gels possess a three-dimensional porous network composed of reduced graphene oxide sheets, which are covered by polyaniline molecules with controlled content. Because of this favorable microstructure, the composite shows a high specific capacitance of 808 F g−1 (5717 mF cm−2) at a current density of 53.33 A g−1 (377.4 mA cm−2), as well as excellent rate performance. These results demonstrate that two-step self-assembly is a promising method for precisely controlling the microstructure of reduced graphene oxide based composite electrode materials.This work was supported by Natural Science Foundation of China (21774104). 该工作得到国家自然科学基金和福建省青年拔尖人才项目的大力资助

Taxonomía y morfología de la yuca

恢复沉水植物是受污染水体生态修复与重建的有效措施之一,人工快速大面积恢复沉水植物的方法是关键。选取杭州西湖西进区域茅家埠和浴鹄湾近岸水域,分别采用扦插法、沉栽法和播种法对沉水植物菹草、苦草和黑藻进行种植。研究表明:运用沉栽法种植的菹草存活率比用播种法种植的存活率高71.1%;运用扦插法种植的苦草比沉栽法和播种法的存活率分别高84.3%和87.8%;运用扦插法种植的黑藻比用播种法种植的存活率高69%;3种种植方式下最终的单株植物生物量间无显著差异

Thermodynamic Analysis of the Efficiency Improvement of a Photovoltaic-thermoelectric Hybrid System

太阳能电池和热电模块组成的复合系统有望获得较高的太阳能到电能的转换效率。本文利用热力学方法分析了由商业化太阳能电池构成的复合系统,并根据一维模型下能流输运特性计算了系统内各模块温度及其对转换效率的影响,发现低温度系数和低效率的太阳能电池可以通过构建复合系统获得更大的性能提升。同时,由于太阳辐照的有限性导致流经热电模块的热流受到限制,因此热电模块效率无法达到理想条件下的最优值。这表明复合系统的优化并非各个模块优化后结果的简单线性叠加,而需要考虑构成复合系统的各个模块间的约束条件进行整体计算和优化,即复合系统效率不仅与材料本征特性(如电导率、热导率等)有关,也和其工作状态(如入射太阳辐照强度、热电模块构成及几何尺寸、模块之间热学特性等)有关。上述模型与结果对于类似复合系统的设计有着指导作用。A hybrid system formed by a photovoltaic module and a thermoelectric module has a great potential to enhance the solar-to-electricity efficiency.A mathematical model based on the first law of thermodynamics and the heat transfer analyses of the hybrid system is built, where the overall efficiency of the system is enhanced by optimizing the system as a whole.The model is used to study hybrid systems formed by commercially available photovoltaic modules and thermoelectric modules.It is found that, due to a limited incoming heat flux for the thermoelectric module, the overall performance of the hybrid system depends not only on the intrinsic properties of the materials forming such a hybrid system, but also on their working conditions, such as incoming solar radiation, geometry of each module, and interfacial properties.The results indicate that only photovoltaic modules with low temperature coefficient and low efficiency can truly benefit from forming such hybrid system, and the optimization of a hybrid system must be done as a whole.教育部高等学校博士学科点专项科研基金新教师项目(20090121120028);教育部高等学校博士学科点专项科研基金博导类项目(20120121110021); 国家自然科学基金项目(U1232110

Biodiversity of the ectomycorrhiza on the rare and endangered tree species Tuga chinensis tchekiangensis(Flous) Cheng in Wuyishan Nature Reserve

对武夷山国家级自然保护区残遗与濒危树种南方铁杉植物群落历经了6年的调查,共采集了123种外生菌根,经显微与超显微技术鉴定了84种,这一结果是迄今为止已发表的,在同一树种中菌根类型最多的记录.它不仅证明了武夷山地区的菌物区系由于处于东西相连,南北贯通的位置上,而且从区系成分上据有温热两带俱全的特点,因而形成生物多样性,并从共生菌的角度再度揭示了物种协同进化的规律.Systematic investigation was made on ectomycorrhizae in the woods of a variety of Tsuga chinensis,tchekiangensis(Flous) Cheng,in Wuyishan Nature Reserve in the past six years.During that period,120 ectomycorrhiza samples were collected and 84 types identified by analysing their macro-micro-and ultrastructure.This is the first time that so many types of mycorrhiza in the forests of the species are reported on.This result has proved Wuyishan's geographical position at the cross where a fungi growing area links the east and west,south and north.Thus the region owns the characteristics of both the temperate and the subtropical zone and it is thus such peculiarity whereby its biodiversity is created.Moreover,considering the results of this investigation in the regard of symbiosis between plants and fungi,their co-evolution is ascertained once more.国家自然科学基金资助项目(39770004);; 福建省自然科学基金资助项目(C97003,D0410002

In situ dynamic tracking of heterogeneous nanocatalytic processes by shell-isolated nanoparticle-enhanced Raman spectroscopy

原位监测纳米催化反应过程对深入认识反应机理、设计高效催化剂具有重要意义。作为一种具有超高灵敏度的表面分析技术，表面增强拉曼光谱（SERS）是可提供反应过程中催化剂表面吸附物种的丰富信息。然而，仅有Au、Ag、Cu等少数金属在形成特定纳米结构时才能提供较强的拉曼增强，且它们会对催化剂的性质及反应过程产生严重干扰。这就极大地限制了SERS在实际多相催化体系中的应用。鉴于此，该论文发展了一种利用壳层隔绝纳米粒子增强拉曼光谱原位监测纳米催化过程的方法。通过将纳米催化剂组装于壳层隔绝纳米粒子表面，形成SHIENRS卫星结构，利用内核Au纳米粒子增强催化剂表面的拉曼信号，SiO2壳层隔绝Au对催化剂及反应的影响，从而直接获得了纳米催化剂表面物种的真实信息。利用这种SHINERS卫星策略，他们实现了CO氧化反应的原位监测，直接观测到了反应条件下催化剂表面吸附物种。并结合DFT计算，对反应机理进行了阐述。该研究表明SHINERS卫星策略可作为原位跟踪催化反应过程的有效方法，为纳米催化的原位研究提供了一种新的思路。 同时，我校也将在今年12月5-9日举办表面增强拉曼光谱国际会议(International Conference on SERS)，讨论SERS领域的最新进展。会议期间，SERS领域的先驱与权威Richard P. Van Duyne、Martin Moskovits、Andreas Otto以及相关学科的顶级学者Peter G. Bruce、Stefan A. Maier等将作大会报告（会议官方网站http://sers2017.xmu.edu.cn/）。【Abstract】Surface molecular information acquired in situ from a catalytic process can greatly promote the rational design of highly efficient catalysts by revealing structure-activity relationships and reaction mechanisms. Raman spectroscopy can provide this rich structural information, but normal Raman is not sensitive enough to detect trace active species adsorbed on the surface of catalysts. Here we develop a general method for in situ monitoring of heterogeneous catalytic processes through shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) satellite nanocomposites (Au-core silica-shell nanocatalyst-satellite structures), which are stable and have extremely high surface Raman sensitivity. By combining operando SHINERS with density functional theory calculations, we identify the working mechanisms for CO oxidation over PtFe and Pd nanocatalysts, which are typical low- and high-temperature catalysts, respectively. Active species, such as surface oxides, superoxide/peroxide species and Pd–C/Pt–C bonds are directly observed during the reactions. We demonstrate that in situ SHINERS can provide a deep understanding of the fundamental concepts of catalysis.This work was supported by the NSFC (21522508, 21427813, 21373167, 21521004, 21573178 and 21673187), Natural Science Foundation of Guangdong Province (2016A030308012), the Fundamental Research Funds for the Central Universities (20720150039 and 20720160046), ‘111’Project (B16029), and the Thousand Youth Talents Plan of China。 研究工作得到国家自然科学基金优秀青年基金、谱学分析创新研究群体和青年千人计划等资助

第十八届美国理论与应用力学大会总结

1会议概况2018年6月5—9日,第18届美国理论与应用力学大会(18th U.S. National Congress of Theoretical and Applied Mechanics, USNCTAM2018)在美国芝加哥召开.本次大会由美国力学国家委员会和中国力学学会联合主办,旨在探讨和交流近四年世界范围内在理论和应用力学领域的基础研究、创新技术的最新进展,吸引了来自世界各地的近千名专家学