102,052 research outputs found
Influence of the threshold settings of photon counting detectors on the observed speckle contrast in coherent scattering experiments
No full textPlasmonic Supercrystals with a Layered Structure Studied by a Combined TEM-SAXS-XCCA Approach
No full textSupercrystals composed of plasmonic nanoparticles constitute a promising material platform for tailored light-matter interactions. The optimization of their optical properties requires precise syntheses and a detailed structural characterization that addresses not only the basic geometrical parameters but also the degree of order. Herein, plasmonic supercrystals with a well-defined layered structure are studied by a combined transmission electron microscopy, small-angle X-ray scattering and X-ray cross-correlation analysis (TEM-SAXS-XCCA) approach. It is demonstrated that scanning small-angle x-ray scattering (SAXS) data can unambiguously be assigned to the number of crystalline layers by comparison with complementary transmission electron microscopy (TEM) experiments on the same regions of interest. A small but significant increase of the lattice constant with increasing number of layers and a high degree of orientational order irrespective of the number of layers is found. This points to specifics of the supercrystal formation mechanism that could be utilized to improve the control of self-assembly for supercrystal geometries with subnanometer precision
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Real-Time X-ray Scattering Discovers Rich Phase Behavior in PbS Nanocrystal Superlattices during in Situ Assembly
No full textDuring the self-organization of colloidal semiconductor nanoparticles by solvent evaporation, nanoparticle interactions are substantially determined by the organic ligands covering the inorganic core. However, the influence of the ligand grafting density on the assembly pathway is often not considered in experiments. Here, we carry out an in situ synchrotron small-angle X-ray scattering and X-ray cross-correlation analysis study of the real-time assembly of oleic acid-capped PbS nanocrystals at a low ligand coverage of 2.7 molecules/nm2. With high temporal and spatial resolution, we monitor the transitions from the colloidal suspension through the solvated superlattice states into the final dried superstructure. In a single in situ experiment, we observe a two-dimensional hexagonal, hexagonal close-packed, body-centered cubic, body-centered tetragonal (with different degrees of tetragonal distortion), and face-centered cubic superlattice phases. Our results are compared to the self-organization of PbS nanocrystals with a higher ligand coverage up to 4.5 molecules/nm2, revealing different assembly pathways. This highlights the importance of determining the ligand coverage in assembly experiments to approach a complete understanding of the assembly mechanism as well as to be able to predict and produce the targeted superstructures
Three-step colloidal gelation revealed by time-resolved x-ray photon correlation spectroscopy
No full textThe gelation of PEGylated gold nanoparticles dispersed in a glycerol-water mixture is probed in situ by x-ray photon correlation spectroscopy. Following the evolution of structure and dynamics over 104 s, a three-step gelation process is found. First, a simultaneous increase of the Ornstein-Zernike length ζ and slowdown of dynamics is characterized by an anomalous q-dependence of the relaxation times of τ ∝ q-6 and strongly stretched intermediate scattering functions. After the structure of the gel network has been established, evidenced by a constant ζ, the dynamics show aging during the second gelation step accompanied by a change toward ballistic dynamics with τ ∝ q-1 and compressed correlation functions. In the third step, aging continues after the arrest of particle motion. Our observations further suggest that gelation is characterized by stress release as evidenced by anisotropic dynamics once gelation sets in
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3346: Samuel G. Freedman, author, 2013
No full textPhotograph of author Samuel G. Freedman, at NT Daily Slash meeting in the Mayborn School of Journalism at UNT
Sectoral job effects of trade: An input-output analysis for Germany
No full textThe current globalisation process is characterized by the emergence of global value chains. That is, production processes are becoming increasingly geographically fragmented. Not only are final goods traded internationally, but in particular, trade in intermediate goods and services has increased significantly over time. In the industrialised countries, the manufacturing sectors were the first that were compelled to face the challenges of globalisation. When services were still considered non-tradable, manufacturing firms had already decided to relocate their production sites to developing or emerging economies, due to lower wage levels abroad and increasing price competition domestically. In this paper, we use input-output analysis to explore the relationship between trade and both job creation and job destruction in the German manufacturing industry in 2005. The results show that being integrated into the world economy is advantageous for the German economy. In 2005, the net exports of the manufacturing industries led to trade-induced job gains of around 2,400,000. This figure is equivalent to 6.2 per cent of total German employment. Furthermore, the job effects of trade were positive for a large majority of countries. The greatest job gains resulted from trade with the United States, the United Kingdom and France. Interestingly, even trade with the new EU Member States is beneficial in terms of job creation. --input-output analysis,international trade,employment
Secondary zoospores in the algal endoparasite Maullinia ectocarpii (Plasmodiophorea).
No full textThe present paper deals with the ultrastructure of zoospores produced by the plasmodiophorid Maullinia ectocarpii , living in the marine algal host Ectocarpus siliculosus. The zoospores described here are very similar to secondary zoospores of Polymyxa graminis and Phagomyxa sp. (the latter an algal endopara- site, also). Our results indicate that M. ectocarpii produces two types of plasmodia, and suggest that is a species with a complete life cycle, as it is known for all the Plasmodiophormycota that have been studied. Sporogenic and sporangial plasmodia produce, respectively, primary zoospores with parallel flagella within thick walled resting sporangia, and secondary zoospores with opposite flagella within thin walled sporangia.Fil: Parodi, Elisa Rosalia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Sur; ArgentinaFil: Caceres, Eduardo Jorge. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Ficología y Micología; ArgentinaFil: Westermeier, Renato. Universidad Austral de Chile; ChileFil: Muller, Dieter G.. Universität Konstanz; Alemani
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