木材功能化研究新进展

木材不仅仅是一种具有可持续、可再生、可生物降解的环境友好型材料,同时具有多级的层次结构、优良的各向异性、多样的化学性能等优点。随着纳米技术及其他先进技术的发展,通过简单的设计制备方法,直接对木材进行自上而下的组装,得到具有功能性的木质材料,打破了木材在实际应用上的局限性,并有希望替代传统的玻璃、塑料等难降解材料。笔者综述了在原木基础上通过对木材成分去除、孔道修饰以及高温碳化等方法处理,赋予木材在不同领域以新应用的相关研究成果;介绍了近年来功能性木材在污水处理、太阳能海水淡化、储能元件、电子器件以及建筑上的应用,并对在应用过程中亟待解决的问题进行了分析;最后对木材科学的发展提出了自己的观点,认为虽然木材在应用上取得了较大突破,但在基础研究上还需要更加深入,木质功能材料走向商业化还面临很大挑战。     

林芝市不同生态功能区空气负离子特征研究

以林芝市7个功能区为研究对象,采用单因素方差和皮尔逊相关系数对空气负离子浓度状况进行研究,以期为市政规划提供参考,促进旅游业的发展。结果表明:1)除商业街外,其他生态功能区空气负离子浓度均为上午<下午;水体、湿地日变化均为三峰型,空旷地、游憩绿地、商业街日动态呈双峰“M”型,林地、绿地日动态表现为单峰型。2)林芝各生态功能区浓度大小为水体(1423个·cm^-3)>绿地(1056个·cm^-3)>空旷地(1039个·cm^-3)>林地(973个·cm^-3)>湿地(812个·cm^-3)>游憩绿地(723个·cm^-3)>商业街(717个·cm^-3),平均浓度为943个·cm^-3,水体旁空气负离子浓度是商业街的1.78倍。水体与其他6种生态功能区差异显著(P<0.05),绿地、空旷地与湿地、游憩绿地、商业街差异显著(P<0.05),其他功能区之间差异不显著(P>0.05)。3)林芝各生态功能区空气质量指数(CI)大小为水体(1.143)>绿地(1.133)>林地(0.935)>湿地(0.921)>游憩绿地(0.891)>空旷地(0.845)>商业街(0.797)。4)空气负离子浓度与温度正相关而不显著(P>0.05),与相对湿度负相关而不显著(P>0.05)。林芝市空气负离子浓度较高、空气质量较好。     

不同年限毛竹-白及复合系统土壤微生物群落多样性特点

为了揭示毛竹-白及复合经营系统中植物-土壤间的互作关系,在安徽省广德市邱村镇选择3个不同套种年限(1、3和4年)的毛竹-白及复合林分为研究对象,采用Biolog-ECO微平板技术,结合主成分分析对培养72 h土壤微生物群落功能多样性及其碳代谢特征进行分析.结果 表明,毛竹-白及复合林分的土壤微生物碳源平均颜色变化率、S...     

果蔬产品中的功能性成分

水果和蔬菜是日常膳食的重要组成部分.本文对果蔬产品中的主要功能性成分如膳食纤维、果低聚糖、植物甾醇、类胡萝卜素、类黄酮、二烯丙基二硫化物、白藜芦醇、环丙基氨酸、异硫氰酸盐、柠檬烯等逐一进行了介绍,并对他们的生理功能进行了简要概述.     

具有Holling-Ⅲ功能反应和脉冲效应的捕食者食饵系统的持续生存与周期性

提出了具有脉冲效应和Holling-Ⅲ类功能反应的比率依赖的捕食者一食饵模型,利用李雅普诺夫泛函和比较方法给出了系统持续生存条件,运用分支理论研究了正周期解的存在性.     

干旱荒漠绿洲区重盐碱地底层衬膜隔盐效果与优质草坪建植研究

为解决河西走廊重盐碱地园林绿化难度大的问题,采用抬高坪床底层衬膜隔盐等技术措施,并结合客土法种植草坪。结果表明:抬高坪床底层衬膜隔盐,即便不换客土也能建植出优质草坪;客土而没有底层衬膜隔盐,虽然草坪苗期生长较好,但随后由于受地下盐分上升的影响,土壤含盐量逐渐上升,草坪质量随之下降;通过相关性分析,草坪质量的各项指标与土壤含盐量呈极显著负相关;因此,重盐碱地底层衬膜隔盐技术可以在干旱荒漠绿洲区农业生产中推广应用。     

不结球白菜BrABF1基因的克隆与功能分析

为研究BrABF1基因在不结球白菜中的表达模式并探索其在开花调控中的作用,本研究以不结球白菜苏州青品种为试验材料,通过同源克隆获得BrABF1基因序列,对其氨基酸序列进行比对和进化分析,利用亚细胞定位技术研究BrABF1的空间表达,采用β-D-葡糖醛酸酶(GUS)染色方法研究BrABF1在植物中的表达模式,利用PlantCARE在线软件预测BrABF1基因的启动子的顺式作用元件。构建植物表达载体pEarlyGate101-BrABF1-YFP转化拟南芥,统计野生型和转基因拟南芥植株的开花时间。结果表明,BrABF1基因含有1 104 bp开放阅读框(ORF),编码367个氨基酸。BrABF1与甘蓝型油菜和野甘蓝(原变种)同源性最高,进化关系最近。BrABF1定位在细胞核上。BrABF1启动子驱动的GUS蛋白主要在拟南芥的叶脉中特异性表达。BrABF1启动子序列包含大量的顺式作用元件,如光响应元件、植物激素响应元件、低温响应元件和逆境胁迫响应元件等。转基因拟南芥植株开花时间晚于野生型,表明BrABF1基因能抑制植物的开花。本研究结果为提高不结球白菜商品价值提供了理论基础。     

Bestimmung der Boden-Wasser-Verteilung leichtflüchtiger Kohlenwasserstoffe mittels Dampfraum-GC

Rapid Headspace-GC determination of the soil-water partition ratio of volatile hydrocarbons The hydrocarbon load of contaminated soils is usually mainly adsorbed to the soil organic matter. The laboratory determination of the sorption equilibration of volatiles suffers from severe drawbacks due to volatilization losses of the analytes and low recoveries if liquid extraction methods are applied. The presented headspace technique for the determination of partition coefficients produces reliable results, also under adsorptive as well as under desorptive conditions. It was shown that the volatiles tested are subject to rather severe ad-/desorption hysteresis which strengthens the necessity to determine the desorptive K_oc in contaminated sites. Additionally significant data were obtained that demonstrated a very strong effect of the organic matters quality on the partition ratios of volatiles.     

Enrichment of the African catfish Clarias gariepinus (Burchell) with functional selenium originating from garlic: effect of enrichment period and depuration on total selenium level and sensory properties

We wanted to optimize the procedure for the selenium enrichment of farmed African catfish, using garlic as dietary selenium source. In the first experiment we established the relation between the length of the selenium enrichment period and the resulting total selenium level in the fillet of the fish. It was found that at a dietary level of 11.7 mg kg^?1 Se, a total selenium level in the fillet of 0.7 mg kg^?1 was reached in a relatively short enrichment period of 10 days before harvest. In the second experiment we studied the effect of depuration on the selenium level in the fillet and the sensory properties of selenium‐enriched African catfish. It was found that total selenium levels in the fillet were not affected during a 7‐day depuration period, while garlic odours and flavours in the raw and cooked fillets were significantly reduced after 2 days of depuration. We concluded that selenium enrichment of farmed African catfish can be obtained by selenium‐enriched finishing diets, while garlic odours and flavours resulting from dietary garlic can be effectively reduced in the fillet during a short depuration period without negatively affecting fillet levels of total selenium.     

Biogeographical region and environmental conditions drive functional traits of estuarine fish assemblages worldwide

Assessing trait–environment relationships is crucial for predicting effects of natural and human‐induced environmental change on biota. We compiled a global database of fish assemblages in estuaries, functional traits of fishes and ecosystem features of estuaries. And we quantified the relative importance of ecosystem features as drivers of patterns of fish functional traits among estuaries worldwide (i.e. drivers of the proportions of fish traits). In addition to biogeographical context, two main environmental gradients regulate traits patterns: firstly temperature, and secondly estuary size and hydrological connectivity of the estuary with the marine ecosystem. Overall, estuaries in colder regions, with larger areas and with higher hydrological connectivity with the marine ecosystem, have higher proportions of marine fish (versus freshwater), macrocarnivores and planktivores (versus omnivores, herbivores and detritivores) and larger fish, with greater maximum depth of distribution and longer lifespan. The observed trait patterns and trait–environment relationships are likely generated by multiple causal processes linked to physiological constraints due to temperature and salinity, size‐dependent biotic interactions, as well as habitat availability and connectivity. Biogeographical context and environmental conditions drive species richness and composition, and present results show that they also drive assemblage traits. The observed trait patterns and trait–environment relationships suggest that assemblage composition is determined by the functional role of species within ecosystems. Conservation strategies should be coordinated globally and ensure protection of an array of estuaries that differ in ecosystem features, even if some of those estuaries do not support high species richness.