2,904 research outputs found
AAS227 - Synthesizing Understanding from Data with yt
No full textThis is a talk I gave at the AAS227 about yt. yt is available at yt-project.org.<div><br></div><div>While I am listed as the author of this talk, the yt community is composed of more than a hundred code contributors and mailing list participants, and we are grateful to their involvement and support.</div><div><br></div><div>Additionally, the yt project is built on other members of the scientific software ecosystem such as Jupyter, NumPy, Cython, h5py and hdf5, Matplotlib, and Sympy.</div
Phase morphology and rheological behavior of polymer/layered silicate nanocomposites
No full textRheological behavior of polymer/layered silicate nanocomposites an strongly dependent not only upon their microstructure but also upon the interfacial characteristics. Different phase morphology (intercalated or exfoliated) of polymer/clay is obtained according to interfacial characteristics between polymer chains and clay. In intercalated structure, the presence of randomly oriented anisotropic stacks of silicate layers is responsible for the enhancement of both moduli. The PS/clay nanocomposites exhibit a slight enhancement at low frequency because of its simple intercalated structure and little interaction. On the other hand, the PS-co-ma/clay nanocomposites have a similar intercalated structure but exhibit a distinct plateau-like behavior at low frequency since the PS-co-ma has a strong attractive interaction with the silicate layers. Finally, PE-g-ma/clay nanocomposites display an exfoliated structure, which exhibit both a distinct plateau-like behavior at low frequency and enhanced moduli at high frequency. Percolation structure as well as large interfacial area between polymer chains and clay are responsible for the theological behavior
Phase morphology and rheological behavior of polymer/layered silicate nanocomposites
No full textRheological behavior of polymer/layered silicate nanocomposites an strongly dependent not only upon their microstructure but also upon the interfacial characteristics. Different phase morphology (intercalated or exfoliated) of polymer/clay is obtained according to interfacial characteristics between polymer chains and clay. In intercalated structure, the presence of randomly oriented anisotropic stacks of silicate layers is responsible for the enhancement of both moduli. The PS/clay nanocomposites exhibit a slight enhancement at low frequency because of its simple intercalated structure and little interaction. On the other hand, the PS-co-ma/clay nanocomposites have a similar intercalated structure but exhibit a distinct plateau-like behavior at low frequency since the PS-co-ma has a strong attractive interaction with the silicate layers. Finally, PE-g-ma/clay nanocomposites display an exfoliated structure, which exhibit both a distinct plateau-like behavior at low frequency and enhanced moduli at high frequency. Percolation structure as well as large interfacial area between polymer chains and clay are responsible for the theological behavior
Cost-effectiveness of different advanced life support providers for victims of out-of –hospital cardiac arrests.
No full textStructural Breaks and Non-Linearities for Predicting the Probability of US Recessions using the Spread
No full textThis paper proposes a structural break threshold model (SBT) to the dynamic relationship between US output growth and the spread between long- and short-term interest rates. This model is able to account for non-linearities, parameter changes and the reduction of the variability of output growth. The SBT model gives better in-sample predictions of the probability of US recessions during 1955-1999 than models with only non-linearity or structural breaks. The presence of a structural break affects the timing and the size of predictions of the probability of recession for 2001.
A fully differential LC-VCO using a new varactor control structure
No full textThis paper presents a fully differential inductor-capacitor voltage-controlled oscillator (LC-VCO) with a new differentially-tuned varactor structure. The proposed LC-VCO has lower phase noise and better robustness to the injected common-mode noise than the differentially-tuned LC-VCO using the previous antiparallel structure. The LC-VCO implemented using 0.5-mum SiGe BiCMOS technology is tunable from 4.251 to 4.428 GHz and the measured phase noise is -119 dBc/Hz at 1-MHz offset over the entire tuning range. Its core current is only 1.7 mA at 2.5-V supply voltage
Recycled oceanic crust-derived fluids in the lithospheric mantle of eastern China. Constraints from oxygen isotope compositions of peridotite xenoliths
No full textThe oxygen isotope compositions of minerals of peridotite xenoliths from the Subei basin, Eastern China were investigated to detect a possible crustal signature in mantle rocks. The delta O-18 values of olivine (ol), orthopyroxene (opx) and clinopyroxene (cpx) vary from 5.10 to 5.98 parts per thousand, 5.46 to 6.78 parts per thousand, and 5.06 to 631 parts per thousand, respectively. Olivine and opx have delta O-18 values similar to-, or above the "expected" mantle range, whereas the delta O-18 values of cpx range from higher to lower than average mantle. These characteristics are inherited from the peridotite mantle source, and likely result from mantle domains that experienced fluid-assisted metasomatism. Coexisting high delta O-18 values of ol and opx and low delta O-18 values of cpx are unlikely to result from selective interactions with the fluids with different delta O-18 values during a single metasomatic event. The measured O-isotope values can be reconciled with a simple two-stage metasomatic model characterized by an early high-delta O-18 fluid/peridotite interaction followed by a late low-delta O-18 fluid infiltration. Model calculations of mineral diffusivities predict that the negative Delta O-18(cpx-ol) values are unlikely to be preserved at mantle conditions for time interval > 80 Ma. Provided the investigated mantle xenoliths were entrained and brought to surface by similar to 9 Ma basaltic eruptions, this also limits the occurrence of the late metasomatic event, and the subducting Pacific plate is the best candidate to provide such fluids. (C) 2015 Elsevier B.V. All rights reserved
Buckyballs
No full textBuckyballs represent a new and fascinating molecular allotropic form of carbon that has received a lot of attention by the chemical community during the
last two decades. The unabating interest on this singular family of highly strained carbon spheres has allowed the establishing of the fundamental chemical reactivity of these carbon cages and, therefore, a huge variety of fullerene derivatives involving [60] and [70]fullerenes, higher fullerenes, and endohedral fullerenes have been prepared. Much less is known, however, of the chemistry of the uncommon non-IPR fullerenes which currently represent a scientific curiosity and which could pave the way to a range of new fullerenes. In this review on buckyballs we
have mainly focused on the most recent and novel covalent chemistry of fullerenes involving metal catalysis and asymmetric synthesis, as well as on some of the most significant advances in supramolecular chemistry, namely H-bonded fullerene assemblies and the search for efficient concave receptors for the convex surface of fullerenes. Furthermore, we have also described the recent advances in the macromolecular chemistry of fullerenes, that is, those polymer molecules endowed with fullerenes which have been classified according to their chemical structures.
This review is completed with the study of endohedral fullerenes, a new family of fullerenes in which the carbon cage of the fullerene contains a metal, molecule, or metal complex in the inner cavity. The presence of these species affords new fullerenes with completely different properties and chemical reactivity, thus opening a new avenue in which a more precise control of the photophysical and redox properties of fullerenes is possible. The use of fullerenes for organic electronics, namely in photovoltaic applications and molecular wires, complements the study and highlights the interest in these carbon allotropes for realistic practical applications. We have pointed out the so-called non-IPR fullerenes – those that do not follow the isolated pentagon rule – as the most intriguing class of fullerenes which, up to now, have only shown the tip of the huge iceberg behind the examples reported in the literature. The number of possible non-IPR carbon cages is almost infinite and the near future will show us whether they will become a reality
Correction to: Chemoradiation in elderly patients with glioblastoma from the multiinstitutional GBMmolRPA cohort: is shortcourse radiotherapy enough or is it a matter of selection?
No full textThe name of author Do Hoon Lim was incorrect in the initial online publication. The original article has been corrected
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