取代苯胺和苯酚类化合物对大型■(Daphnia magna Straus)的定量结构-活性关系研究

研究了３６个取代苯胺和苯酚类化合物对大型的急性毒性，应用正辛醇／水分配系数、线性溶解能关系参数和分子连接性指数得出了该类化合物的定量构效关系方程，这些方程可以用来进行该类化合物危害性初评．ＬＳＥＲ法得到的ＱＳＡＲ方程拟合效果较好，增大分子体积及偶极性极化性，均可增大毒性．化合物与蛋白质等生物大分子的氢键键合作用是导致该类化合物毒性高于其基本毒性的原因．     

取代苯甲酸在天然河流中的生物降解及其定量结构--生物降解性相关研究

以天然河流水作为微生物源 ,采用碘量法测定了 2 0种苯甲酸类化合物的 5日生化需氧量 ,并以其占理论需氧量的百分数作为表征生物降解性的参数 ,得出各类取代苯甲酸类化合物的生物降解能力为 :羟基 >氨基 >羧基 >甲氧基 >氯基 >硝基 ;对于同一种取代基 ,对位取代基化合物生物降解能力最大 ,而邻位、间位取代基化合物生物降解能力大体相同。计算了苯甲酸类化合物的分子连接性指数 ,并以 5日生化需氧量占理论需氧量的百分数为参数建立了 QSBR模型。分析结果表明 ,分子连接性指数5Xvpc、5Xp- 5Xvp 能较好地反映取代苯甲酸的生物降解性     

苯的衍生物在活性炭/水界面上的吸附标准自由能及与其分子结构的关系

测定了25℃时活性炭自水中吸附苯、苯酚、苯胺、对－氯苯酚、苯甲酸、对－羟基苯甲酸、对－氯苯胺、硝基苯、对－氨基苯甲酸、对－硝式苯酚、对－硝基苯胺、对硝基苯甲酸的等温线，它们的等温线均为Langmuir型的，利用Langmuir参数计算了吸吸标准自由能变化△G^0，计算结果表明，△G^0具有加和性，即化合物的△G^0是组成该化合物各基团贡献之总和，化合物的分子量及分子连接性指数与△G^0有近似的线性关系。     

Experimental and theoretical studies on NO selective catalytic oxidation over α-MnO2

Based on the experimental and theoretical methods, the NO selective catalytic oxidation process was proposed. The experimental results indicated that lattice oxygen was the active site for NO oxide over the $\mathrm{\alpha }$-MnO₂(110) surface. In the theoretical study, DFT (density functional theory) and periodic slab modeling were performed on an $\mathrm{\alpha }$-MnO₂(110) surface, and two possible NO oxidation mechanisms over the surface were proposed. The non-defect $\mathrm{\alpha }$-MnO₂(110) surface showed the highest stability, and the surface O_s (the second layer oxygen atoms) position was the most active and stable site. O₂ molecule enhanced the joint adsorption process of two NO molecules. The reaction process, including O₂ dissociation and O=N-O-O-N=O formation, was calculated to carry out the NO catalytic oxidation mechanism over $\mathrm{\alpha }$-MnO₂(110). The results showed that NO oxidation over the $\mathrm{\alpha }$-MnO₂(110) surface exhibited the greatest possibility following the route of O=N-O-O-N=O formation. Meanwhile, the formation of O=N-O-O-N=O was the rate-determining step.     

Mechanical Properties with the Functional Group of Additives for Starch/PVA Blend Film

This paper deals with the mechanical properties and degree of swelling (DS) of starch/PVA blend film with the functional groups i.e., hydroxyl and carboxyl group, of additives. Starch/PVA blend films were prepared by using the mixing process. Glycerol (GL) with 3 hydroxyl group, sorbitol (SO) with 6 hydroxyl group, succinic acid (SA) with 2 carboxyl group, malic acid (MA) with 1 hydroxyl and 2 carboxyl group, tartaric acid (TA) with 2 hydroxyl and 2 carboxyl group and citric acid (CA) with 1 hydroxyl and 3 carboxyl group were used as additives. The results of measured tensile strength (TS) and elongation (%E) verified that both hydroxyl and carboxyl group as a functional groups increased the flexibility and strength of the film. Values of DS for GL-added and SA-added films were low. However, DS values of the films added MA, TA or CA with both hydroxyl and carboxyl group were comparatively high. When the film was dried at low temperature, the properties of the films were evidently improved. The reason is probably because the hydrogen bonding was activated at low temperature.     

Trait space of rare plants in a fire‐dependent ecosystem

The causes of species rarity are of critical concern because of the high extinction risk associated with rarity. Studies examining individual rare species have limited generality, whereas trait‐based approaches offer a means to identify functional causes of rarity that can be applied to communities with disparate species pools. Differences in functional traits between rare and common species may be indicative of the functional causes of species rarity and may therefore be useful in crafting species conservation strategies. However, there is a conspicuous lack of studies comparing the functional traits of rare species and co‐occurring common species. We measured 18 important functional traits for 19 rare and 134 common understory plant species from North Carolina's Sandhills region and compared their trait distributions to determine whether there are significant functional differences that may explain species rarity. Flowering, fire, and tissue‐chemistry traits differed significantly between rare and common, co‐occurring species. Differences in specific traits suggest that fire suppression has driven rarity in this system and that changes to the timing and severity of prescribed fire may improve conservation success. Our method provides a useful tool to prioritize conservation efforts in other systems based on the likelihood that rare species are functionally capable of persisting.     

Characterizing the Width of Amphibian Movements During Postbreeding Migration

Habitat linkages can help maintain connectivity of animal populations in developed landscapes. However, the lack of empirical data on the width of lateral movements (i.e., the zigzagging of individuals as they move from one point to point another) makes determining the width of such linkages challenging. We used radiotracking data from wood frogs (Lithobates sylvaticus) and spotted salamanders (Ambystoma maculatum) in a managed forest in Maine (U.S.A.) to characterize movement patterns of populations and thus inform planning for the width of wildlife corridors. For each individual, we calculated the polar coordinates of all locations, estimated the vector sum of the polar coordinates, and measured the distance from each location to the vector sum. By fitting a Gaussian distribution over a histogram of these distances, we created a population‐level probability density function and estimated the 50th and 95th percentiles to determine the width of lateral movement as individuals progressed from the pond to upland habitat. For spotted salamanders 50% of lateral movements were ≤13 m wide and 95% of movements were ≤39 m wide. For wood frogs, 50% of lateral movements were ≤17 m wide and 95% of movements were ≤ 51 m wide. For both species, those individuals that traveled the farthest from the pond also displayed the greatest lateral movement. Our results serve as a foundation for spatially explicit conservation planning for pond‐breeding amphibians in areas undergoing development. Our technique can also be applied to movement data from other taxa to aid in designing habitat linkages. Caracterización de la Amplitud de Movimiento de Anfibios durante la Migración Pos‐Reproducción     

Defining and Evaluating the Umbrella Species Concept for Conserving and Restoring Landscape Connectivity

Conserving or restoring landscape connectivity between patches of breeding habitat is a common strategy to protect threatened species from habitat fragmentation. By managing connectivity for some species, usually charismatic vertebrates, it is often assumed that these species will serve as conservation umbrellas for other species. We tested this assumption by developing a quantitative method to measure overlap in dispersal habitat of 3 threatened species—a bird (the umbrella), a butterfly, and a frog—inhabiting the same fragmented landscape. Dispersal habitat was determined with Circuitscape, which was parameterized with movement data collected for each species. Despite differences in natural history and breeding habitat, we found substantial overlap in the spatial distributions of areas important for dispersal of this suite of taxa. However, the intuitive umbrella species (the bird) did not have the highest overlap with other species in terms of the areas that supported connectivity. Nevertheless, we contend that when there are no irreconcilable differences between the dispersal habitats of species that cohabitate on the landscape, managing for umbrella species can help conserve or restore connectivity simultaneously for multiple threatened species with different habitat requirements. Definición y Evaluación del Concepto de Especie Paraguas para Conservar y Restaurar la Conectividad de Paisajes     

Trait‐based prediction of extinction risk of small‐bodied freshwater fishes

Small body size is generally correlated with r‐selected life‐history traits, including early maturation, short‐generation times, and rapid growth rates, that result in high population turnover and a reduced risk of extinction. Unlike other classes of vertebrates, however, small freshwater fishes appear to have an equal or greater risk of extinction than large fishes. We explored whether particular traits explain the International Union for Conservation of Nature (IUCN) Red List conservation status of small‐bodied freshwater fishes from 4 temperate river basins: Murray‐Darling, Australia; Danube, Europe; Mississippi‐Missouri, North America; and the Rio Grande, North America. Twenty‐three ecological and life‐history traits were collated for all 171 freshwater fishes of ≤120 mm total length. We used generalized linear mixed‐effects models to assess which combination of the 23 traits best explained whether a species was threatened or not threatened. We used the best models to predict the probability of 29 unclassified species being listed as threatened. With and without controlling for phylogeny at the family level, small body size—among small‐bodied species—was the most influential trait correlated with threatened species listings. The k‐folds cross‐validation demonstrated that body size and a random effect structure that included family predicted the threat status with an accuracy of 78% (SE 0.5). We identified 10 species likely to be threatened that are not listed as such on the IUCN Red List. Small body size is not a trait that provides universal resistance to extinction, particularly for vertebrates inhabiting environments affected by extreme habitat loss and fragmentation. We hypothesize that this is because small‐bodied species have smaller home ranges, lower dispersal capabilities, and heightened ecological specialization relative to larger vertebrates. Trait data and further model development are needed to predict the IUCN conservation status of the over 11,000 unclassified freshwater fishes, especially those under threat from proposed dam construction in the world's most biodiverse river basins.