1,547 research outputs found
Recyclable Pd(OAc)₂/Ligand/Al(OTf)₃ catalyst for the homogeneous methoxycarbonylation and hydrocarboxylation reactions of phenylacetylene
The Pd-catalyzed methoxycarbonylation reaction of phenylacetylene was studied making use of various promoters, including aluminum triflate and several other acid-type promoters of this reaction. The influence of the ligand (bidentate-type ligands and monodentate analogues) was found to be determinative of the success of the reaction. The catalyst was found to be recyclable through 10 catalytic runs. The unique results when using BINAP, relating to the selectivity for the branched product and the stability of the catalyst produced, led to a study on the sulfonated analogue thereof, with the intention of performing hydrocarboxylation reactions to directly prepare the carboxylic acid. The product obtained accordingly may be varied between the methyl ester or its carboxylic acid equivalent, depending on the solvent medium and the ligand employed
An Intrisic Topology for Orthomodular Lattices
We present a general way to define a topology on orthomodular lattices. We
show that in the case of a Hilbert lattice, this topology is equivalent to that
induced by the metrics of the corresponding Hilbert space. Moreover, we show
that in the case of a boolean algebra, the obtained topology is the discrete
one. Thus, our construction provides a general tool for studying orthomodular
lattices but also a way to distinguish classical and quantum logics.Comment: Under submission to the International Journal of Theoretical Physic
Seasonal SIMS δ18O record in Astarte borealis from the Baltic Sea tracks a modern regime shift in the NAO
Introduction: Astarte borealis holds great potential as an archive of seasonal paleoclimate, especially due to its long lifespan (several decades to more than a century) and ubiquitous distribution across high northern latitudes. Furthermore, recent work demonstrates that the isotope geochemistry of the aragonite shell is a faithful proxy of environmental conditions. However, the exceedingly slow growth rates of A. borealis in some locations (<0.2mm/year) make it difficult to achieve seasonal resolution using standard micromilling techniques for conventional stable isotope analysis. Moreover, oxygen isotope (δ18O) records from species inhabiting brackish environments are notoriously difficult to use as paleoclimate archives because of the simultaneous variation in temperature and δ18Owater values. Methods: Here we use secondary ion mass spectrometry (SIMS) to microsample an A. borealis specimen from the southern Baltic Sea, yielding 451 SIMS δ18Oshell values at sub-monthly resolution. Results: SIMS δ18Oshell values exhibit a quasi-sinusoidal pattern with 24 local maxima and minima coinciding with 24 annual growth increments between March 1977 and the month before specimen collection in May 2001. Discussion: Age-modeled SIMS δ18Oshell values correlate significantly with both in situ temperature measured from shipborne CTD casts (r2 = 0.52, p<0.001) and sea surface temperature from the ORAS5-SST global reanalysis product for the Baltic Sea region (r2 = 0.42, p<0.001). We observe the strongest correlation between SIMS δ18Oshell values and salinity when both datasets are run through a 36-month LOWESS function (r2 = 0.71, p < 0.001). Similarly, we find that LOWESS-smoothed SIMS δ18Oshell values exhibit a moderate correlation with the LOWESS-smoothed North Atlantic Oscillation (NAO) Index (r2 = 0.46, p<0.001). Change point analysis supports that SIMS δ18Oshell values capture a well-documented regime shift in the NAO circa 1989. We hypothesize that the correlation between the SIMS δ18Oshell time series and the NAO is enhanced by the latter’s influence on the regional covariance of water temperature and δ18Owater values on interannual and longer timescales in the Baltic Sea. These results showcase the potential for SIMS δ18Oshell values in A. borealis shells to provide robust paleoclimate information regarding hydroclimate variability from seasonal to decadal timescales
Edge Radial Electric Field Structure and its Connection to H-Mode Confinement in Alcator C-Mod
Development of real-time reverse transcription polymerase chain reaction assays to quantify insulin-like growth factor receptor and insulin receptor expression in equine tissue
The insulin-like growth factor system (insulin-like growth factor 1, insulin-like growth factor
2, insulin-like growth factor 1 receptor, insulin-like growth factor 2 receptor and six insulinlike
growth factor-binding proteins) and insulin are essential to muscle metabolism and most
aspects of male and female reproduction. Insulin-like growth factor and insulin play important
roles in the regulation of cell growth, differentiation and the maintenance of cell differentiation
in mammals. In order to better understand the local factors that regulate equine physiology,
such as muscle metabolism and reproduction (e.g., germ cell development and fertilisation),
real-time reverse transcription polymerase chain reaction assays for quantification of equine
insulin-like growth factor 1 receptor and insulin receptor messenger ribonucleic acid were
developed. The assays were sensitive: 192 copies/μL and 891 copies/μL for insulin-like growth
factor 1 receptor, messenger ribonucleic acid and insulin receptor respectively (95% limit of
detection), and efficient: 1.01 for the insulin-like growth factor 1 receptor assay and 0.95 for the
insulin receptor assay. The assays had a broad linear range of detection (seven logs for insulinlike
growth factor 1 receptor and six logs for insulin receptor). This allowed for analysis of
very small amounts of messenger ribonucleic acid. Low concentrations of both insulin-like
growth factor 1 receptor and insulin receptor messenger ribonucleic acid were detected in
endometrium, lung and spleen samples, whilst high concentrations were detected in heart,
muscle and kidney samples, this was most likely due to the high level of glucose metabolism
and glucose utilisation by these tissues. The assays developed for insulin-like growth factor 1
receptor and insulin receptor messenger ribonucleic acid expression have been shown to work
on equine tissue and will contribute to the understanding of insulin and insulin-like growth
factor 1 receptor physiology in the horse.http://www.ojvr.orgam201
Power requirements for superior H-mode confinement on Alcator C-Mod: Experiments in support of ITER
Partial Description of Quantum States
One of the most central and controversial element of quantum mechanics is the
use of non zero vectors of a Hilbert space (or, more generally, of one
dimension subspaces) for representing the state of a quantum system. In
particular, the question whether such a representation is complete has been
debated since almost the early days of quantum mechanics. In this article, we
develop an alternate way to formalize knowledge about the state of quantum
systems, based solely on experimentally accessible elements, namely on outcomes
of finite measurements. We introduce what we call partial description which,
given a feasible measurement, indicates some outcomes which are known to be
impossible (i.e. known to have a probability equal to 0 to occur) and hence
have to be discarded. Then, we introduce partial states (which are partial
descriptions providing as much information as possible) and compare this way to
describe quantum states to the orthodox one, using vector rays. Finally, we
show that partial states allow to describe quantum states in a strictly more
expressive way that the orthodox description does
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