Three-dimensional plasmon rulers

Plasmon rulers can be used to determine nanoscale distances within chemical or biological species. They are based on the spectral shift of the scattering spectrum when two plasmonic nanoparticles approach one another. However, the one-dimensionality of current plasmon rulers hampers the comprehensive understanding of many intriguing processes in soft matter, which take place in three dimensions. We demonstrated a three-dimensional plasmon ruler that is based on coupled plasmonic oligomers in combination with high-resolution plasmon spectroscopy. This enables retrieval of the complete spatial configuration of complex macromolecular and biological processes as well as their dynamic evolution.     

影响烟草特有亚硝胺积累的因素

把Ｎｉｃｏｔｉａｎａ ｐｌｕｍｂａｇｉｎｉｆｏｌｉａ的基因突变种子和普通种子发芽后嫁接在Ｗｅｓｃｏｎｓｉｎ３８烟株上,与温室条件下正常盆栽生长的Ｎｉｃｏｔｉａｎａ ｐｌｕｍｂａｇｉｎｉｆｏｌｉａ和母体Ｗｅｓｃｏｎｓｉｎ３８分析比较,试验结果得出：Ｗｅｓｃｏｎｓｉｎ３８上嫁接Ｎｉｃｏｔｉａｎａ ｐｌｕｍｂａｇｉｎｉｆｏｌｉａ基因突变种子还原酶活性最高,晾制后烟叶中烟草特有的亚硝胺含量次之;温室盆栽的     

Scaling in the time domain: universal dynamics of order fluctuations in Fe3Al

By focusing a highly brilliant synchrotron x-ray beam to a micrometer spot on a sample, we measured in real time the x-ray intensity fluctuations associated with order fluctuations in crystalline materials. We applied this method to the binary alloy Fe3Al near its continuous A2-B2 phase transformation and determined a specific four-point time correlation function for the order parameter. From a detailed theoretical analysis, dynamical scaling in the time domain with a transition from noncritical to critical dynamics is disclosed.     

Complex multicolor tilings and critical phenomena in tetraphilic liquid crystals

T-shaped molecules with a rod-like aromatic core and a flexible side chain form liquid crystal honeycombs with aromatic cell walls and a cell interior filled with the side chains. Here, we show how the addition of a second chain, incompatible with the first (X-shaped molecules), can form honeycombs with highly complex tiling patterns, with cells of up to five different compositions ("colors") and polygonal shapes. The complexity is caused by the inability of the side chains to separate cleanly because of geometric frustration. Furthermore, a thermoreversible transition was observed between a multicolor (phase-separated) and a single-color (mixed) honeycomb phase. This is analogous to the Curie transition in simple and frustrated ferro- and antiferromagnets; here spin flips are replaced by 180° reorientations of the molecules.     

The role of weathering and forestry in determining the acidity of Lakes in Sweden

The long term acidity level of a lake is determined by the balance between acidity input to the catchment and the generation of alkalinity in the catchment. If the input of acidity through biomass net production and the production of alkalinity through weathering of minerals can be estimated, then the steady-state acidity level can be calculated for the lake under a certain acid deposition rate. Such a calculation has been carried out for 8 lakes ranging from acid to neutral. For lakes with the most sensitive soils in the catchment, the critical acid deposition load that will permit the lake to stay neutral, may be less than zero acidity, indicating that the forest growth is contributing to the acidification of very sensitive system under the present forest managements methods.     

Taxonomy and evolution of cultivated plants: Literature review 1985/1986

Summary Important papers on taxonomy and evolution of cultivated plants published in 1985 and 1986 were compiled and briefly discussed.

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Taxonomie und Evolution der Kulturpflanzen: Literaturübersicht 1985/1986

Zusammenfassung Wichtige Arbeiten über Taxonomie und Evolution der Kulturpflanzen aus den Jahren 1985 und 1986 wurden zusammengestellt und kurz kommentiert.

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¶rt; : 1985–1986

¶rt; , 1985 1986 . .

     

Feeding deterrence and contact toxicity of Stemona alkaloids-a source of potent natural insecticides

On the basis of chronic feeding bioassays with neonate larvae of Spodoptera littoralis reared on an artificial diet, the methanolic leaf and root extracts from Stemona collinsae displayed very high insect toxicity compared to those of two Aglaia species, a commercial Pyrethrum extract, and azadirachtin, whereas S. tuberosa extracts demonstrated low activity in roots and no activity in leaves. Beyond that, in leaf disk choice tests against fifth instar larvae, S. collinsae showed strong antifeedant activity, whereas S. tuberosa was characterized by remarkable repellency. The anti-insect properties of both species were based on pyrrolo[1,2-a]azepine alkaloids, from which didehydrostemofoline (asparagamine A) was the major compound of the roots of S. collinsae, exhibiting the highest toxicity in feeding assays. Saturation and hydroxylation of the side chain in the co-occurring stemofoline and 2'-hydroxystemofoline, respectively, led to an increasing loss of activity. Contact toxicity tests with stemofoline and didehydrostemofoline exhibited even higher activities than those of Pyrethrum extract. Tuberostemonine was the dominating alkaloid in the roots of S. tuberosa, showing outstanding repellency but no toxic effects.     

Taxonomy and evolution of cultivated plants: Literature review 1983/1984

Summary Important papers on taxonomy and evolution of cultivated plants published in 1983 and 1984 were complied and briefly discussed.

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Taxonomie und Evolution der Kulturpflanzen: Literaturübersicht 1983/1984

Zusammenfassung Wichtige Arbeiten über Taxonomie und Evolution der Kulturpflanzen aus den Jahren 1983 und 1984 wurden zusammengestellt und kurz kommentiert.

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: 1983–1984

, 1983 1984 . .