木本植物内源生长素免疫胶体金定位分析技术的研究

以木本植物杨树(Populus sp.)和核桃(Juglans regia L.)为材料,对内源生长素免疫胶体金定位技术在固定、烤片、免疫染色、显色等关键环节进行了改进优化与验证.结果显示,优化后适合木本植物定位方法的主要技术要点是:在染色中,通过采用尿素-胰蛋白酶联合消化技术和增加牛血清白蛋白处理大大地改善了抗原修复结果,提高了染色的敏感性和特异性.利用优化后的方法对核桃幼胚和杨树嫩茎诱导生根过程中的吲哚乙酸(IAA)进行定位研究,发现杨树试管嫩茎生根过程中,形成层及周缘维管束有很强的IAA信号,核桃子叶生根中,胚中有很强的IAA信号,胚根中有半圆形、胚芽中有>"形强信号区,胚轴信号较弱,胚根信号最强.研究表明,与传统免疫染色方法相比,优化后的方法对木本植物生长素定位具有敏感性高,特异性强,银颗粒明显,背景清晰,耗时少等特点.     

层状双金属氢氧化物及其在药物传递系统中的应用研究现状

层状双金属氢氧化物作为一种新型无机纳米载体材料,具有独特优势,近年来其在各类药物传递系统中的应用已成为研究热点。介绍层状双金属氢氧化物的制备与修饰,分类综述其在不同药物传递系统中的应用研究。     

基于物质流分析方法的唐山市经济与环境关系的协整检验和分解

利用物质流分析方法(MFA)建立物质流账户,分析唐山市在经济 环境系统运行中物质投入量与产出量的阶段特征及物质投入和产出强度对经济发展的影响程度;使用计量经济学模型,分别对国内生产总值(GDP)、直接物质投入(DMI)和直接废弃物排放(DPO)进行单位根检验、Johansen协整检验、向量误差修正分析、脉冲响应和方差分解分析,探索了各指标之间的双向作用机制和长期关系.结果表明: 1992—2011年,唐山市DMI和DPO 均呈增长趋势,DMI的增幅高于DPO.DMI投入强度呈增长趋势,DPO产出强度呈波动下降趋势.GDP与DMI、DPO之间存在着长期稳定协整关系,指标间的作用关系经历了由波动到逐步平稳的过程.DMI与DPO在短期内会对经济发展起到较强的正向冲击作用,但是经济-环境系统会逐步消化这些影响,并对系统内外指标进行短期的动态调整,最终使系统表现出一种长期的均衡关系;经济发展受到经济规模效应的影响逐步增加.将各指标对GDP的贡献度予以分解,其中,DMI的贡献度上升,GDP的贡献度下降,DPO的贡献度变化不大.总体上,唐山市的经济发展遵循了资源型城市的传统生产轨迹,较大程度上依赖于物质投入,高能源消耗又加剧了环境污染.     

The ecological impact of bush encroachment on the yield of grasses in Borana rangeland ecosystem

The ecological impact of woody encroachment and the responses of herbage yield to encroachment were assessed at three locations in Borana rangeland at the end of the growing season. The study was carried out in two communal grazing areas (Medhecho and Dubluk) and one Government ranch (Dida‐Tuyura) in bush and/or shrub encroached and non‐encroached sites. In each area, three altitude ranges were distinguished and in each altitude range one transect, covering both encroached and non‐encroached rangeland, was selected. The assessment was based on the yield and botanical composition of the herbaceous layer. The grasses Cenchrus ciliaris, Chrysopogon aucheri and Panicum coloratum were common or dominant in both encroached and non‐encroached sites. Pennisetum mezianum and Pennise‐tum stramineum were typically found in encroached vegetation. The relative yield increased with non‐encroached sites and varied at different altitude ranges from about 106% to about 150%, thus increases ranged from 75% in Medhecho to 350% in Dubluk as determined from the lower values of the ranges. The encroached vegetation had a significantly lower score for herbage yield than the non‐encroached vegetation for most of the sites, although the differences were small. Differences based on altitude range were also significant for Eragrostis papposa and Pennisetum stramineum, while the three areas showed a significant difference for the mean yield of Aristida adscensionis, Cenchrus ciliaris and Eragrostis papposa.     

Changes in bird communities in Swaziland savannas between 1998 and 2008 owing to shrub encroachment

Aim This study investigates changes in bird communities between 1998 and 2008 in four savanna sites in Swaziland and the extent to which shrub encroachment is responsible for these changes. Location Swaziland, southern Africa. Methods Generalized estimated equations were used to estimate changes in bird species occurrence between 1998 and 2008. Remote sensing of aerial photographs/satellite images was used to assess vegetation changes during the same period. We assessed the role of shrub encroachment for bird communities by testing the relationship between change in species occurrence and species habitat using a general linear model. We also estimated species richness, colonization and extinction and used general linear models to test the effects of vegetation changes on these parameters. Results More than half of the bird species showed a significant change in occurrence between 1998 and 2008: 32 species increased and 29 decreased. Change in species occurrence was significantly explained by species habitat. Species significantly increasing were mainly associated with wooded savanna, whereas species significantly decreasing were mainly associated with open savanna. Species richness decreased significantly, and this decrease was significantly explained by shrub cover increase at the plot scale (from 24% to 44% on average). Extinction at the plot scale was significantly influenced by the loss of grass cover, while colonization at the plot scale was influenced by tree cover increase. Main conclusions This study represents the first evidence of temporal changes in bird communities owing to shrub encroachment in southern Africa. Despite its short time frame (10 years), this study shows dramatic changes in both vegetation structure and bird community composition. This confirms the general concern for southern African bird species associated with open savanna if current trends continue.     

Photoluminescence and piezoelectric behaviour of Y2Zr2O7 pyrochlore‐based multifunctional materials and the influence of Eu3+ and Sm3+

Y₂Zr₂O₇‐doped with Eu³⁺ and Sm³⁺ phosphors were prepared for the first time as multifunctional smart materials using a solid‐state reaction method at 1400^oC. Thermal behaviour, crystal structure, surface morphology, and elemental analysis were characterized using thermogravimetric (TG) and differential thermal (DTA) analyses, X‐ray diffraction (XRD) and scanning electron microscope equipped with energy‐dispersive X‐ray spectroscopy (SEM‐EDX). Experimental results revealed that both phosphors have a pyrochlore structure with a cubic crystal system. Photoluminescence properties were also measured and red emission was observed from Y_1.90Eu_0.10Zr₂O₇ and Y_1.90Sm_0.10Zr₂O₇ phosphors. Dielectric constant, loss tangent, piezoelectric charge constant, and Curie temperature of all the samples were determined using an LCR‐meter, d₃₃‐meter, and TG/DTA. Eu doping in Y₂Zr₂O₇ resulted in a high dielectric constant (9.61) and low loss tangent (1.67%) values, whereas high piezoelectric charge constant (0.68 pC/N) and high Curie temperature (820°C) could be obtained using Sm‐doped Y₂Zr₂O₇.     

Multiple trade‐offs regulate the effects of woody plant removal on biodiversity and ecosystem functions in global rangelands

Woody plant encroachment is a major land management issue. Woody removal often aims to restore the original grassy ecosystem, but few studies have assessed the role of woody removal on ecosystem functions and biodiversity at global scales. We collected data from 140 global studies and evaluated how different woody plant removal methods affected biodiversity (plant and animal diversity) and ecosystem functions (plant production, hydrological function, soil carbon) across global rangelands. Our results indicate that the impact of removal is strongly context dependent, varying with the specific response variable, removal method, and traits of the target species. Over all treatments, woody plant removal increased grass biomass and total groundstorey diversity. Physical and chemical removal methods increased grass biomass and total groundstorey biomass (i.e., non‐woody plants, including grass biomass), but burning reduced animal diversity. The impact of different treatment methods declined with time since removal, particularly for total groundstorey biomass. Removing pyramid‐shaped woody plants increased total groundstorey biomass and hydrological function but reduced total groundstorey diversity. Environmental context (e.g., aridity and soil texture) indirectly controlled the effect of removal on biomass and biodiversity by influencing plant traits such as plant shape, allelopathic, or roots types. Our study demonstrates that a one‐size‐fits‐all approach to woody plant removal is not appropriate, and that consideration of woody plant identity, removal method, and environmental context is critical for optimizing removal outcomes. Applying this knowledge is fundamental for maintaining diverse and functional rangeland ecosystems as we move toward a drier and more variable climate.     

Relationships of reproductive performance indicators in black rhinoceros (Diceros bicornis michaeli) with plant available moisture,plant available nutrients and woody cover

Plant available moisture and plant available nutrients in soils influence forage quality and availability and subsequently affect reproductive performance in herbivores. However, the relationship of soil moisture, soil nutrients and woody forage with reproductive performance indicators is not well understood in mega‐browsers yet these three are important in selecting suitable areas for conservation of mega‐browsers. Here, the eastern black rhinoceros (Diceros bicornis michaeli), a mega‐browser, was studied in seven geographically distinct populations in Kenya to understand the relationships between its reproductive performance indicators and plant available moisture, plant available nutrients and woody cover. Reproductive parameters showed a complex relationship with plant available moisture and plant available nutrients. We found an increase in the predicted yearly percentage of females calving as plant available nutrients decreased in areas of high levels of plant available moisture but no relationship with plant available nutrients in areas of low plant available moisture. Age at first calving was earlier, inter‐calving interval was longer and yearly percentage of females calving was higher at higher woody cover. Woody plant cover contributes positively to black rhino reproduction performance indicators, whereas plant available moisture and plant available nutrients add to the selection of conservation areas, in more subtle ways.