524 research outputs found
Interfacial layering in a three-component polymer system
We study theoretically the temporal evolution and the spatial structure of
the interface between two polymer melts involving three different species (A,
A* and B). The first melt is composed of two different polymer species A and A*
which are fairly indifferent to one another (Flory parameter chi_AA* ~ 0). The
second melt is made of a pure polymer B which is strongly attracted to species
A (chi_AB 0). We then show
that, due to these contradictory tendencies, interesting properties arise
during the evolution of the interface after the melts are put into contact: as
diffusion proceeds, the interface structures into several adjacent
"compartments", or layers, of differing chemical compositions, and in addition,
the central mixing layer grows in a very asymmetric fashion. Such unusual
behaviour might lead to interesting mechanical properties, and demonstrates on
a specific case the potential richness of multi-component polymer interfaces
(as compared to conventional two-component interfaces) for various
applications.Comment: Revised version, to appear in Macromolecule
Density functional calculations of nanoscale conductance
Density functional calculations for the electronic conductance of single
molecules are now common. We examine the methodology from a rigorous point of
view, discussing where it can be expected to work, and where it should fail.
When molecules are weakly coupled to leads, local and gradient-corrected
approximations fail, as the Kohn-Sham levels are misaligned. In the weak bias
regime, XC corrections to the current are missed by the standard methodology.
For finite bias, a new methodology for performing calculations can be
rigorously derived using an extension of time-dependent current density
functional theory from the Schroedinger equation to a Master equation.Comment: topical review, 28 pages, updated version with some revision
Identification of expression QTL (eQTL) of genes expressed in porcine M. longissimus dorsi and associated with meat quality traits
<p>Abstract</p> <p>Background</p> <p>Genetic analysis of transcriptional profiles is a promising approach for identifying and dissecting the genetics of complex traits like meat performance. Accordingly, expression levels obtained by microarray analysis were taken as phenotypes in a linkage analysis to map eQTL. Moreover, expression levels were correlated with traits related to meat quality and principle components with high loadings of these traits. By using an up-to-date annotation and localization of the respective probe-sets, the integration of eQTL mapping data and information of trait correlated expression finally served to point to candidate genes for meat quality traits.</p> <p>Results</p> <p>Genome-wide transcriptional profiles of <it>M. longissimus dorsi </it>RNAs samples of 74 F2 animals of a pig resource population revealed 11,457 probe-sets representing genes expressed in the muscle. Linkage analysis of expression levels of these probe-sets provided 9,180 eQTL at the suggestive significance threshold of LOD > 2. We mapped 653 eQTL on the same chromosome as the corresponding gene and these were designated as 'putative <it>cis-</it>eQTL'. In order to link eQTL to the traits of interest, probe-sets were addressed with relative transcript abundances that showed correlation with meat quality traits at p ≤ 0.05. Out of the 653 'putative <it>cis-</it>eQTL', 262 transcripts were correlated with at least one meat quality trait. Furthermore, association of expression levels with composite traits with high loadings for meat quality traits generated by principle component analysis were taken into account leading to a list of 85 genes exhibiting <it>cis-</it>eQTL and trait dependent expression.</p> <p>Conclusion</p> <p>Holistic expression profiling was integrated with QTL analysis for meat quality traits. Correlations between transcript abundance and meat quality traits, combined with genetic positional information of eQTL allowed us to prioritise candidate genes for further study.</p
Developments in the negative-U modelling of the cuprate HTSC systems
The paper deals with the many stands that go into creating the unique and
complex nature of the HTSC cuprates above Tc as below. Like its predecessors it
treats charge, not spin or lattice, as prime mover, but thus taken in the
context of the chemical bonding relevant to these copper oxides. The crucial
shell filling, negative-U, double-loading fluctuations possible there require
accessing at high valent local environment as prevails within the mixed valent,
inhomogeneous two sub-system circumstance of the HTSC materials. Close
attention is paid to the recent results from Corson, Demsar, Li, Johnson,
Norman, Varma, Gyorffy and colleagues.Comment: 44 pages:200+ references. Submitted to J.Phys.:Condensed Matter, Sept
7 200
Path Dependence in the Law: The Course and Pattern of Legal Change in a Common Law System
Modeling Spatial Sustainability: Spatial Welfare Economics versus Ecological Footprint
Green electrochemical template synthesis of CoPt nanoparticles with tunable size, composition, and magnetism from microemulsions using an ionic liquid (bmimPF6)
Altres ajuts: Substrates have been prepared in IMB-CNM (CSIC),supported by the (CSIC) NGG-258 project.Electrodeposition from microemulsions using ionic liquids is revealed as a green method for synthesizing magnetic alloyed nanoparticles, avoiding the use of aggressive reducing agents. Microemulsions containing droplets of aqueous solution (electrolytic solution containing Pt(IV) and Co(II) ions) in an ionic liquid (bmimPF) define nanoreactors in which the electrochemical reduction takes place. Highly crystalline hcp alloyed CoPt nanoparticles, in the 10-120 nm range with a rather narrow size distribution, have been deposited on a conductive substrate. The relative amount of aqueous solution to ionic liquid determines the size of the nanoreactors, which serve as nanotemplates for the growth of the nanoparticles and hence determine their size and distribution. Further, the stoichiometry (PtCo) of the particles can be tuned by the composition of the electrolytic solution inside the droplets. The control of the size and composition of the particles allows tailoring the room-temperature magnetic behavior of the nanoparticles from superparaparamagnetic to hard magnetic (with a coercivity of H = 4100 Oe) in the as-obtained state. © 2014 American Chemical Society
Overlapping Intellectual Property Doctrines: Election of Rights versus Selection of Remedies
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