107,380 research outputs found
Viscoelastic gels of guar and xanthan gum mixtures provide long-term stabilization of iron micro- and nanoparticles
No full textIron micro- and nanoparticles used for groundwater remediation and medical applications are prone to fast aggregation and sedimentation. Diluted single biopolymer water solutions of guar gum (GG) or xanthan gum (XG) can stabilize these particles for few hours providing steric repulsion and by increasing the viscosity of the suspension. The goal of the study is to demonstrate that amending GG solutions with small amounts of XG (XG/GG weight ratio 1:19; 3 g/L of total biopolymer concentration) can significantly improve the capability of the biopolymer to stabilize highly concentrated iron micro- and nanoparticle suspensions. The synergistic effect between GG and XG generates a viscoelastic gel that can maintain 20 g/L iron particles suspended for over 24 h. This is attributed to (i) an increase in the static viscosity, (ii) a combined polymer structure the yield stress of which contrasts the downward stress exerted by the iron particles, and (iii) the adsorption of the polymers to the iron surface having an anchoring effect on the particles. The XG/GG viscoelastic gel is characterized by a marked shear thinning behavior. This property, coupled with the low biopolymer concentration, determines small viscosity values at high shear rates, facilitating the injection in porous media. Furthermore, the thermosensitivity of the soft elastic polymeric network promotes higher stability and longer storage times at low temperatures and rapid decrease of viscosity at higher temperatures. This feature can be exploited in order to improve the flowability and the delivery of the suspensions to the target as well as to effectively tune and control the release of the iron particle
SETHI: The Flying Lab
No full textThis paper presents the new-generation test bench SETHI, developed by ONERA, the French Aerospace Lab. SETHI is a medium range platform dedicated to environmental, scientific and security applications. The first part of this paper describes the system architecture, the development state and the future capabilities. A set of recent significant results are presented: these results cover various applications, such as high spatial resolution imaging, change detection between two acquisitions, biomass measurement in the rain forest, bistatic imaging and innovative measurements, such as air-to-air imaging or circular imaging
Transport of Non-Newtonian Suspensions of Highly Concentrated Micro- And Nanoscale Iron Particles in Porous Media: A Modeling Approach
No full textThe use of zerovalent iron micro- and nanoparticles (MZVI and NZVI) for groundwater remediation is hindered by colloidal instability, causing aggregation (for NZVI) and sedimentation (for MZVI) of the particles. Transportability of MZVI and NZVI in porous media was previously shown to be significantly increased if viscous shear-thinning fluids (xanthan gum solutions) are used as carrier fluids. In this work, a novel modeling approach is proposed and applied for the simulation of 1D flow and transport of highly concentrated (20 g/L) non- Newtonian suspensions of MZVI and NZVI, amended with xanthan gum (3 g/L). The coupled model is able to simulate the flow of a shear thinning fluid including the variable apparent viscosity arising from changes in xanthan and suspended iron particle concentrations. The transport of iron particles is modeled using a dual-site approach accounting for straining and physicochemical deposition/release phenomena. A general formulation for reversible deposition is herein proposed, that includes all commonly applied dynamics (linear attachment, blocking, ripening). Clogging of the porous medium due to deposition of iron particles is modeled by tying porosity and permeability to deposited iron particles. The numerical model proved to adequately fit the transport tests conducted using both MZVI and NZVI and can develop into a powerful tool for the design and the implementation of full scale zerovalent iron application
7-deaza-8-bromo-cyclic ADP-ribose, the first membrane-permeant, hydrolysis-resistant cyclic ADP-ribose antagonist
No full textCyclic ADP-ribose (cADPR) is a putative second messenger that has been demonstrated to mobilize Ca2+ in many cell types. Its postulated role as the endogenous regulator of ryanodine-sensitive Ca2+ release channels has been greatly supported by the advent and use of specific cADPR receptor antagonists such as 8-NH2-cADPR (Walseth, T. F., and Lee, H. C. (1993) Biochim. Biophys. Acta 1178, 235-242). However, investigations of the role of cADPR in physiological responses, such as fertilization, stimulus-secretion coupling, and excitation-contraction coupling, have been hindered by the susceptibility of cADPR receptor antagonists to hydrolysis and the need to introduce these molecules into cells by microinjection or patch clamp techniques. We have recently reported on the discovery of a poorly hydrolyzable analogue of cADPR, 7-deaza-cADPR (Bailey, V. C., Sethi, J. K., Fortt, S. M., Galione, A., and Potter, B. V. L. (1997) Chem. Biol. 4, 41-51) but this, like cADPR, is an agonist of ryanodine-sensitive Ca2+ release channels. We therefore explored the possibility of combining antagonistic activity with that of hydrolytic resistance and now report on the biological properties of the first hydrolysis-resistant cADPR receptor antagonist, 7- deaza-8-bromo-cADPR. In addition this compound has the advantage of being membrane-permeable. Together these properties make this hybrid molecule the most powerful tool to date for studying cADPR-mediated Ca2+ signaling in intact cells.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Auszüglein Des Edlen Seelen-Schatzes M. Sethi Calvisii, Pastoris, Darinnen der Kleine Kinder-Catechismus Lutheri, Neben andern hieraus entstehenden kurtzen und einfältigen Kinderfragen und Antwort/ Absonderlich abgefasset
No full textAUSZÜGLEIN DES EDLEN SEELEN-SCHATZES M. SETHI CALVISII, PASTORIS, DARINNEN DER KLEINE KINDER-CATECHISMUS LUTHERI, NEBEN ANDERN HIERAUS ENTSTEHENDEN KURTZEN UND EINFÄLTIGEN KINDERFRAGEN UND ANTWORT/ ABSONDERLICH ABGEFASSET
Auszüglein Des Edlen Seelen-Schatzes M. Sethi Calvisii, Pastoris, Darinnen der Kleine Kinder-Catechismus Lutheri, Neben andern hieraus entstehenden kurtzen und einfältigen Kinderfragen und Antwort/ Absonderlich abgefasset ( - )
Cover ( - )
Titelseite ([1]r)
Beitrag ([1]v)
Kinderfragen und Antwort von der H. Christlichen Catechismus - Lehre ([2]r)
I. Vom ersten Hauptstück des H. Catechsimi ([2]v)
II. Vom andern Hauptstück des H. Catechismi ([11]r)
III. Vom dritten Hauptstück des. H. Catechismi ([19]r)
IV. Vom vierdten Hauptstück des H. Catechismi ([31]v)
V. Vom fünfften Hauptstück des H. Catechismi ([42]v)
Christliche Fragstück/ durch D. Martinum Lutherum gestellet/ für die/ so zum Sacrament geben wollen / mit ihren Antworten ([49]v)
Imprint ([58]v
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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
The construction of Karen Karnak: The multi-author-function
No full textThis thesis is situated within the comparatively recent developments of Web 2.0 and the emergence of interactive WikiMedia, and explores the mode of authorship within a Read/Write culture compared to that of a Read/Only tradition. The hypothesis of this study is that the role of the audience has become merged with the author, and as such, represents new functions and attributes, distinct from a more conventional concept of authorship, in which the roles of audience and author are more separate. Read/Write and participatory culture, as defined by this study, is focused on collaboration, and includes the influences of D.I.Y. culture, Open-Source practices and the production of text by multiple authors. Multi-authorship presents a re-thinking of several concepts which support the notion of the individual author, since the focus of multi-authorship is not on attribution and ownership of a finished text, but on the continued malleability of a text. Modes of multi-authorship, demonstrated in the use of the pseudonyms Alan Smithee and Karen Eliot, represent declarative authors whose names signify multiple origins, whilst concurrently indicating a distinct body of work. The function of these names form an important context to this study, since primary research involves the construction of an experimental mode of multi-authorship utilising WikiMedia technology and the interaction of thirty nine participants, who are invited to create a body of work under the collective pseudonym Karen Karnak. The data generated by this experiment is analysed using aspects of Michel Foucault's author-function to identify and determine power structures inherent in the WikiMedia context. The interplay of power structures, including concepts such as identity, ownership and the body of work, affect the resulting mode of authorship and contribute to the construction of Karen Karnak, suggesting further areas of research into the emerging multi-author
Contribution of Information and Communication Technology (ICT) in Country’S H-Index
No full textThe aim of this study is to examine the effect of Information and Communication Technology (ICT) development on country’s scientific ranking as measured by H-index. Moreover, this study applies ICT development sub-indices including ICT Use, ICT Access and ICT skill to find the distinct effect of these sub-indices on country’s H-index. To this purpose, required data for the panel of 14 Middle East countries over the period 1995 to 2009 is collected. Findings of the current study show that ICT development increases the H-index of the sample countries. The results also indicate that ICT Use and ICT Skill sub-indices positively contribute to higher H-index but the effect of ICT access on country’s H-index is not clear
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