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排序方式: 共有86条查询结果,搜索用时 15 毫秒
81.
M. Anselmino M. Boglione U. D’Alesio A. Kotzinian S. Melis F. Murgia A. Prokudin C. Türk 《The European Physical Journal A - Hadrons and Nuclei》2009,39(1):89-100
We study the Sivers effect in the transverse single spin asymmetries (SSA) for pion and kaon production in semi-inclusive
deep inelastic scattering (SIDIS) processes. We perform a fit of which, by including recent high-statistics experimental data for pion and kaon production from HERMES and COMPASS Collaborations,
allows a new determination of the Sivers distribution functions for quarks and antiquarks with u , d and s flavours. Estimates for forthcoming SIDIS experiments at COMPASS and JLab are given. 相似文献
82.
P. Melis 《Journal of Radioanalytical and Nuclear Chemistry》2001,249(2):355-360
In Sardinia, the Italian island in the middle of the MediterraneanSea, there are many red soils developed on limestone or dolomite. Soil andunderlying bedrock samples from 5 different sites have been submitted to chemicaland mineralogical characterization, by using standard X-ray diffraction analysis,spectrochemical methods and instrumental neutron activation analysis. Obtainedresults are presented and discussed in terms of precision and accuracy. Traceelement concentration variation with depth is discussed as well as the enrichment/depletionratios between soils and rocks, and the rare-earth element distribution. Dataanalysis suggests for some soils a formation process based on the evolutionof the underlying bedrock, and for the other soils a formation process partlybased on the evolution of the local rock but with meaningful contributionsof external sources, both eolian and/or alluvial. 相似文献
83.
The crystal structures of three polyesteramides of the type conventionally referred to as nNTm, i.e. 6NT6, 12NT6 and 12NT12, were investigated by X-ray diffraction methods. The copolymers crystallize with triclinic symmetry and the repeat distances along the chain axis are 31.78(8), 39.27(20) and 46.77(15) Å, respectively. In 6NT6, the crystal structure of which was studied in more detail, the conformation of the molecular chain displays some departure from the fully extended form, particularly by rotation of the amide and the ester groups (about 26 and 15°, respectively) away from the plane of the benzene ring. Layers of chains, linked together by intermolecular hydrogen bonds, are formed. For the other two copolymers. evidence was obtained for a rather close isomorphism. A model of a structural disorder is proposed and discussed for the 6NT6 copolymer. 相似文献
84.
Anna-Maria Tsirigoni Melis Goktas Zeynep Atris Angelo Valleriani Ana Vila Verde Kerstin G. Blank 《Macromolecular bioscience》2023,23(5):2200563
Coiled coils (CCs) are key building blocks of biogenic materials and determine their mechanical response to large deformations. Of particular interest is the observation that CC-based materials display a force-induced transition from α-helices to mechanically stronger β-sheets (αβT). Steered molecular dynamics simulations predict that this αβT requires a minimum, pulling speed-dependent CC length. Here, de novo designed CCs with a length between four to seven heptads are utilized to probe if the transition found in natural CCs can be mimicked with synthetic sequences. Using single-molecule force spectroscopy and molecular dynamics simulations, these CCs are mechanically loaded in shear geometry and their rupture forces and structural responses to the applied load are determined. Simulations at the highest pulling speed (0.01 nm ns−1) show the appearance of β-sheet structures for the five- and six-heptad CCs and a concomitant increase in mechanical strength. The αβT is less probable at a lower pulling speed of 0.001 nm ns−1 and is not observed in force spectroscopy experiments. For CCs loaded in shear geometry, the formation of β-sheets competes with interchain sliding. β-sheet formation is only possible in higher-order CC assemblies or in tensile-loading geometries where chain sliding and dissociation are prohibited. 相似文献
85.
John Peter Coats Rémy Cochereau Ionel Adrian Dinu Daniel Messmer Flavien Sciortino Cornelia. G. Palivan 《Macromolecular bioscience》2023,23(8):2200474
Polymeric nano- and microscale materials bear significant potential in manifold applications related to biomedicine. This is owed not only to the large chemical diversity of the constituent polymers, but also to the various morphologies these materials can achieve, ranging from simple particles to intricate self-assembled structures. Modern synthetic polymer chemistry permits the tuning of many physicochemical parameters affecting the behavior of polymeric nano- and microscale materials in the biological context. In this Perspective, an overview of the synthetic principles underlying the modern preparation of these materials is provided, aiming to demonstrate how advances in and ingenious implementations of polymer chemistry fuel a range of applications, both present and prospective. 相似文献
86.