208 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
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
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
Gel gradient electrophoresis, isoelectric focusing and two-dimensional techniques in horizontal, ultrathin polycrylamide layers
No full textAn ultrathin layer, horizontal polyacrylamide gel system for electrophoresis, isoelectric focusing and two-dimensional techniques is described. Gel slabs 240 micron thin for unidimensional, or 360 micron thin for two-dimensional runs are cast on cellophane foils as support. The sample is loaded in pockets pre-cast in the gel (2--3 microliter size) or in trenches for two-dimensional experiments. The second dimension is routinely performed in concave exponential gel gradients, spanning an acrylamide concentration from 4% to 22.5%. The sensitivity with the common Coomassie Blue stain is very high, well below 0.1 microgram protein/band. Zymogram detections can be developed within a few minutes, thus retaining the band sharpness of the focused zones or of the bands separated in pore gradient electrophoresis. Sample handling, staining and destaining and gel drying and storage are greatly simplified and performed in a fraction of the time needed for conventional, thick gels in the 1-2 mm thickness range
Jobs gained and lost through trade: The case of Germany
No full textThe nature of international trade has changed significantly. For centuries, trade concentrated on the exchange of finished goods. It now increasingly involves bits of value that are added at different locations to combine into one final product. Therefore, trade in functions or tasks are of growing importance and exports of final goods are no longer an appropriate indicator of the international competitiveness of countries. The process of globalisation has an impact on domestic labour markets. Due to the increasing integration of the world economy, some jobs are gained and others lost in any open economy. Concerns about German workers losing jobs to foreign competition dominate many political debates. Many people fear that being integrated in the world economy is disadvantageous for Germany. In this paper, we use input-output analysis to explore the relationship between trade and both job creation and job destruction in Germany over the period 1995-2006. We present two main findings. First, in an autarkic situation, around 7.0 per cent of total German jobs would not have existed at all in 2006. The job effect of trade was positive in every reporting year. Second, the manufacturing sector contributed most to this positive job effect, but also in the service sector, many jobs were retained through trade. --input-output analysis,international trade,employment
Isoelectric focusing in immobilized pH gradients: principle, methodology and some applications
No full textA new technique for generating pH gradients in isoelectric focusing is described, based on the principle that the buffering groups are covalently linked to the matrix used as anticonvective medium. For the generation of this type of pH gradient in polyacrylamide gels, a set of buffering monomers, called Immobiline (in analogy with Ampholine), is used. The pH gradient gels are cast in the same way as pore gradient gels, but instead of varying the acrylamide content, the light and heavy solutions are adjusted to different pH values with the aid of the Immobiline buffers. Available Immobiline species make it possible to generate any narrow linear pH gradient between pH 3 and 10. The behaviour of these types of gradients in isoelectric focusing is described. Immobilized pH gradients show a number of advantages compared with carrier ampholyte generated pH gradients. The most important are: (1) the cathodic drift is completely abolished; (2) they give higher resolution and higher loading capacity; (3) they have uniform conductivity and buffering capacity; (4) they represent a milieu of known and controlled ionic strength
Morphological, genotypic and metabolomic signatures confirm interfamilial hybridization between the ubiquitous kelps Macrocystis (Arthrothamnaceae) and Lessonia (Lessoniaceae)
No full textWe thank the support from G. Millne (UoA), M. Rateb (UoA) and D. Zagal (UACh) in the histological preparations, mass spectrometry set-up and the cultivation of the hybrid progeny, respectively. PM and LM developed part of this work with BecasChile (Fondecyt) funding, specifically grants No. 72130422 (PM) and No. 73140389 (LM). We would like to acknowledge the British Council Newton Fund Institutional Links, project No. 261781172 for funding SS a postdoctoral research fellow. We are also grateful to the UK Natural Environment Research Council for their support to FCK (program Oceans 2025–WP 4.5 and grants NE/D521522/1 and NE/ J023094/1). This work also received support from the Marine Alliance for Science and Technology for Scotland pooling initiative. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions. RW thanks financial support from Gobierno Regional de Los Lagos (grants FIC 2012 E7259-2 and FIC 2013 BIP30234872-0) and Fondef, Conicyt (HUAM AQ12I0010), which allows the sampling expeditions at Chiloe Island by PM, LM, DJP. Publisher Correction: Morphological, genotypic and metabolomic signatures confirm interfamilial hybridization between the ubiquitous kelps Macrocystis (Arthrothamnaceae) and Lessonia (Lessoniaceae) (Scientific Reports, (2020), 10, 1, (8279), 10.1038/s41598-020-65137-3) Pedro Murúa, Ru Angelie Edrada-Ebel, Liliana Muñoz, Sylvia Soldatou, Nathalie Legrave, Dieter G. Müller, David J. Patiño, Pieter van West, Frithjof C. Küpper, Renato Westermeier, Rainer Ebel, Akira F. Peters, 2020, vol. 10, issue 1. Scientific Reports http://dx.doi.org/10.1038/s41598-020-68820-7Peer reviewe
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