193 research outputs found
Synthesis and Spectroscopic Characterization of 1,â8-âNaphthalimide Derived "Super" Photoacids
The ground- and excited-âstate acid-âbase properties of three novel naphthalimide-âbased "super" photoacids were studied using steady-âstate and time-âresolved spectroscopy. The compds. exhibit pKa = 8.8-â8.0 and pK*a = -â1.2 to -â1.9. The decrease in both ground- and excited-âstate pKa is achieved by attachment of an electron withdrawing group (sulfonate) on the arom. system. All compds. are deprotonated upon excitation in alcs. and DMSO. Good correlation is established between the pK*a and the ratio of the neutral and anion emission intensities in a certain solvent. The excited-âstate intermol. proton transfer to solvent (H2O and DMSO) is explained by a two-âstep model. In the first step, short-ârange proton transfer takes place, resulting in the formation of a contact ion pair. Free ion pairs are formed in the diffusion controlled second step
Experimental investigation of low octane fuel composition effects on load range capacity in Partially Premixed Combustion (PPC)
Abstract Manente and coworkers [1] discovered that a fuel in the gasoline boiling range with 70 Octane Number (ON70) is applicable for Partially Premixed Combustion (PPC) over the complete load range without additional engine adaptations. Using such a fuel in combination with an appropriate dilution strategy was shown to simultaneously achieve low emissions and high efficiency without any drawback in combustion control. In the present paper the load range applicability of ON70 fuels in PPC is further investigated. To do so, four fuels in the ON70 range are selected, with different chemical and physical properties. The goal of testing these fuels is to achieve low emissions and high efficiency over the complete load range of PPC
Effect of grazing and mowing on the clonal structure of Elytrigia atherica: a long-term study of abandoned and managed sites
Physical disturbance by large herbivores can affect species diversity at the community level and concurrently
genetic diversity at the species level. As seedling establishment is rarely observed in clonal
plants, short-term experiments and demographic studies are unlikely to reveal the response of clonal
plants to disturbances. A long-term (30-year) field experiment and the availability of molecularmarkers
allowed us to investigate the clonal structure of populations of Elytrigia atherica subjected to different
management regimes. The long-term field study provided us with five replicated blocks that had
been subjected to three different management regimes, grazing by cattle, mowing and abandonment.
In this study we examined the effects of herbivore grazing andmowing on clonal richness and genetic
diversity of populations in salt marshes using multilocus microsatellite genotypes. In addition,
phenotypic traits and spatial positions of E. atherica ramets were determined for 20 samples in a 5 Ă 10m
plot in each of the blocks. Abundance and phenotypic traits were affected by the management
regimes, resulting in a higher abundance in abandoned fields and plants having shorter and narrower
leaves in managed fields. Biomass removal did affect the clonal structure of populations and increased
the genetic diversity compared to that in abandoned fields. However, no distinct difference was found
between the two management regimes, mowing and grazing. Although seedling recruitment has
rarely been observed, the present study shows that such rare events have occurred within the populations
studied. Thus, molecular tools can greatly increase our understanding of vegetation dynamics
and processes within populations growing under different conditions
Scaling relations for auxin waves
We analyze an 'up-the-gradient' model for the formation of transport channels of the phytohormone auxin, through auxin-mediated polarization of the PIN1 auxin transporter. We show that this model admits a family of travelling wave solutions that is parameterized by the height of the auxin-pulse. We uncover scaling relations for the speed and width of these waves and verify these rigorous results with numerical computations. In addition, we provide explicit expressions for the leading-order wave profiles, which allows the influence of the biological parameters in the problem to be readily identified. Our proofs are based on a generalization of the scaling principle developed by Friesecke and Pego to construct pulse solutions to the classic Fermi-Pasta-Ulam-Tsingou model, which describes a one-dimensional chain of coupled nonlinear springs.Analysis and Stochastic
Renormalized Poincar\'e algebra for effective particles in quantum field theory
Using an expansion in powers of an infinitesimally small coupling constant
, all generators of the Poincar\'e group in local scalar quantum field
theory with interaction term are expressed in terms of annihilation
and creation operators and that result from a
boost-invariant renormalization group procedure for effective particles. The
group parameter is equal to the momentum-space width of form factors
that appear in vertices of the effective-particle Hamiltonians, . It
is verified for terms order 1, , and , that the calculated generators
satisfy required commutation relations for arbitrary values of .
One-particle eigenstates of are shown to properly transform under
all Poincar\'e transformations. The transformations are obtained by
exponentiating the calculated algebra. From a phenomenological point of view,
this study is a prerequisite to construction of observables such as spin and
angular momentum of hadrons in quantum chromodynamics.Comment: 17 pages, 5 figure
Special relativity constraints on the effective constituent theory of hybrids
We consider a simplified constituent model for relativistic
strong-interaction decays of hybrid mesons. The model is constructed using
rules of renormalization group procedure for effective particles in light-front
quantum field theory, which enables us to introduce low-energy phenomenological
parameters. Boost covariance is kinematical and special relativity constraints
are reduced to the requirements of rotational symmetry. For a hybrid meson
decaying into two mesons through dissociation of a constituent gluon into a
quark-anti-quark pair, the simplified constituent model leads to a rotationally
symmetric decay amplitude if the hybrid meson state is made of a constituent
gluon and a quark-anti-quark pair of size several times smaller than the
distance between the gluon and the pair, as if the pair originated from one
gluon in a gluonium state in the same effective theory.Comment: 11 pages, 5 figure
Effect of metabolic genetic variants on long-term disease comorbidity in patients with type 2 diabetes
Underlying genetic determinants contribute to developing type 2 diabetes (T2D) future diseases. The present study aimed to identify which genetic variants are associated with the incident of the major T2D co-morbid disease. First, we conducted a discovery study by investigating the genetic associations of comorbid diseases within the framework of the Utrecht Cardiovascular Pharmacogenetic studies by turning information of > 25Â years follow-up data of 1237 subjects whom were genotyped and included in the discovery study. We performed Cox proportional-hazards regression to examine associations between genetic variants and comorbid diseases including cardiovascular diseases (CVD), chronic eye disease, cancer, neurologic diseases and chronic kidney disease. Secondly, we replicated our findings in two independent cohorts consisting of 1041 subjects. Finally, we performed a meta-analysis by combining the discovery and two replication cohorts. We ascertained 390 (39.7%) incident cases of CVD, 182 (16.2%) of chronic eye disease, 155 (13.8%) of cancer, 31 (2.7%) of neurologic disease and 13 (1.1%) of chronic kidney disease during a median follow-up of 10.2Â years. In the discovery study, we identified a total of 39 Single Nucleotide Polymorphisms (SNPs) associated with comorbid diseases. The replication study, confirmed that rs1870849 and rs8051326 may play a role in the incidence of chronic eye disease in T2D patients. Half of patients developed at least one comorbid disease, with CVD occurring most often and earliest followed by chronic eye disease. Further research is needed to confirm the associations of two associated SNPs with chronic eye disease in T2D
Measurement of the cross section for isolated-photon plus jet production in pp collisions at âs=13 TeV using the ATLAS detector
The dynamics of isolated-photon production in association with a jet in protonâproton collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset with an integrated luminosity of 3.2 fbâ1. Photons are required to have transverse energies above 125 GeV. Jets are identified using the anti- algorithm with radius parameter and required to have transverse momenta above 100 GeV. Measurements of isolated-photon plus jet cross sections are presented as functions of the leading-photon transverse energy, the leading-jet transverse momentum, the azimuthal angular separation between the photon and the jet, the photonâjet invariant mass and the scattering angle in the photonâjet centre-of-mass system. Tree-level plus parton-shower predictions from Sherpa and Pythia as well as next-to-leading-order QCD predictions from Jetphox and Sherpa are compared to the measurements
- âŠ