690 research outputs found
Thermophysical study of 2-acetylthiophene: experimental and modelled results
Several thermophysical properties have been studied for 2-acetylthiophene: (i) vapour pressure was determined at temperatures within 336.16–445.02 K; (ii) density, speed of sound, static permittivity, refractive index, surface tension, and kinematic viscosity were measured at p = 0.1 MPa and at temperatures from 278.15 K (or 283.15 K for the refractive index) to 338.15 K; (iii) volumetric properties were also determined at temperatures in the (283.15–338.15) K range and at pressures up to 65.0 MPa. From these experimental values, different derivative properties have been calculated such as enthalpy of vaporization, isobaric expansibility, isothermal and isentropic compressibility, dipole moment, entropy and enthalpy of surface formation, and dynamic viscosity. All experimental properties were correlated and the results were explained through the intermolecular interactions. Moreover PC-SAFT EoS was used to model the thermodynamic behaviour of the compound. Finally, this EoS combined with the Density Gradient Theory allowed obtaining the influence parameter for the surface tension of 2-acetylthiophene
Cyrhetrenylaniline and new organometallic phenylimines derived from 4- and 5-nitrothiophene: Synthesis, characterization, X-Ray structures, electrochemistry and in vitro anti-T. brucei activity
A novel series of cyrhetrenyl (3a-4a) and ferrocenyl (3b-4b) Schiff bases were synthesized through a condensation reaction, between the known 4-ferrocenylaniline (2b) or the unreported 4-cyhretrenylaniline (2a) with 4- or 5-nitrothiophenecarboxaldehyde. The structure of 2a and the new Schiff bases have been elucidated using conventional spectroscopic techniques (FT-IR, 1H and 13C NMR), mass spectrometry, and single-crystal X-ray diffraction analysis of compounds 2a, 4a and 3b. Cyclic voltammetry of organometallic phenylimines derived from 5-nitrothiophene showed NO2 group reduction potentials (E1/2z 0.575 V) that were more anodic than those registered for their 4-nitro analogues (E1/2z 0.981 V). All organometallic imines were tested against the bloodstream form of Trypanosoma brucei. Evaluation indicated that the most active complexes are the 5-nitrothiophene derivatives, 4a, which were remarkably more active than nifurtimox. In addition, complex 4b resulted in less toxicity to host L6 cells than nifurtimox. The results revealed that the electronic effects of cyrhetrene and ferrocene are not an influential factor in E1/2 and anti-Trypanosoma brucei activity for these new imines, which is probably due to the non-coplanarity of the [(h5-C5H4)-C6H4-N=CH-(C4H2S)] system
Soliton Interactions in Perturbed Nonlinear Schroedinger Equations
We use multiscale perturbation theory in conjunction with the inverse
scattering transform to study the interaction of a number of solitons of the
cubic nonlinear Schroedinger equation under the influence of a small correction
to the nonlinear potential. We assume that the solitons are all moving with the
same velocity at the initial instant; this maximizes the effect each soliton
has on the others as a consequence of the perturbation. Over the long time
scales that we consider, the amplitudes of the solitons remain fixed, while
their center of mass coordinates obey Newton's equations with a force law for
which we present an integral formula. For the interaction of two solitons with
a quintic perturbation term we present more details since symmetries -- one
related to the form of the perturbation and one related to the small number of
particles involved -- allow the problem to be reduced to a one-dimensional one
with a single parameter, an effective mass. The main results include
calculations of the binding energy and oscillation frequency of nearby solitons
in the stable case when the perturbation is an attractive correction to the
potential and of the asymptotic "ejection" velocity in the unstable case.
Numerical experiments illustrate the accuracy of the perturbative calculations
and indicate their range of validity.Comment: 28 pages, 7 figures, Submitted to Phys Rev E Revised: 21 pages, 6
figures, To appear in Phys Rev E (many displayed equations moved inline to
shorten manuscript
Quantum entanglement in photosynthetic light harvesting complexes
Light harvesting components of photosynthetic organisms are complex, coupled,
many-body quantum systems, in which electronic coherence has recently been
shown to survive for relatively long time scales despite the decohering effects
of their environments. Within this context, we analyze entanglement in
multi-chromophoric light harvesting complexes, and establish methods for
quantification of entanglement by presenting necessary and sufficient
conditions for entanglement and by deriving a measure of global entanglement.
These methods are then applied to the Fenna-Matthews-Olson (FMO) protein to
extract the initial state and temperature dependencies of entanglement. We show
that while FMO in natural conditions largely contains bipartite entanglement
between dimerized chromophores, a small amount of long-range and multipartite
entanglement exists even at physiological temperatures. This constitutes the
first rigorous quantification of entanglement in a biological system. Finally,
we discuss the practical utilization of entanglement in densely packed
molecular aggregates such as light harvesting complexes.Comment: 14 pages, 7 figures. Improved presentation, published versio
Role of quantum coherence in chromophoric energy transport
The role of quantum coherence and the environment in the dynamics of
excitation energy transfer is not fully understood. In this work, we introduce
the concept of dynamical contributions of various physical processes to the
energy transfer efficiency. We develop two complementary approaches, based on a
Green's function method and energy transfer susceptibilities, and quantify the
importance of the Hamiltonian evolution, phonon-induced decoherence, and
spatial relaxation pathways. We investigate the Fenna-Matthews-Olson protein
complex, where we find a contribution of coherent dynamics of about 10% and of
relaxation of 80%.Comment: 5 pages, 3 figures, included static disorder, correlated environmen
Genetic Architecture of ADHD and Overlap With Other Psychiatric Disorders And Cognition-Related Phenotypes
Attention-deficit/hyperactivity disorder (ADHD) co-occurs with many other psychiatric disorders and traits. In this review, we summarize and interpret the existing literature on the genetic architecture of these comorbidities based on hypothesis-generating approaches. Quantitative genetic studies indicate that genetic factors play a substantial role in the observed co-occurrence of ADHD with many different disorders and traits. Molecular genetic correlations derived from genome-wide association studies and results of studies based on polygenic risk scores confirm the general pattern but provide effect estimates that are smaller than those from twin studies. The identification of the specific genetic variants and biological pathways underlying co-occurrence using genome-wide approaches is still in its infancy. The first analyses of causal inference using genetic data support causal relationships between ADHD and comorbid disorders, although bidirectional effects identified in some instances point to complex relationships. While several issues in the methodology and inferences from the results are still to be overcome, this review shows that the co-occurrence of ADHD with many psychiatric disorders and traits is genetically interpretable.</p
Genetic Architecture of ADHD and Overlap With Other Psychiatric Disorders And Cognition-Related Phenotypes
Attention-deficit/hyperactivity disorder (ADHD) co-occurs with many other psychiatric disorders and traits. In this review, we summarize and interpret the existing literature on the genetic architecture of these comorbidities based on hypothesis-generating approaches. Quantitative genetic studies indicate that genetic factors play a substantial role in the observed co-occurrence of ADHD with many different disorders and traits. Molecular genetic correlations derived from genome-wide association studies and results of studies based on polygenic risk scores confirm the general pattern but provide effect estimates that are smaller than those from twin studies. The identification of the specific genetic variants and biological pathways underlying co-occurrence using genome-wide approaches is still in its infancy. The first analyses of causal inference using genetic data support causal relationships between ADHD and comorbid disorders, although bidirectional effects identified in some instances point to complex relationships. While several issues in the methodology and inferences from the results are still to be overcome, this review shows that the co-occurrence of ADHD with many psychiatric disorders and traits is genetically interpretable.</p
Genetic Architecture of ADHD and Overlap With Other Psychiatric Disorders And Cognition-Related Phenotypes
Attention-deficit/hyperactivity disorder (ADHD) co-occurs with many other psychiatric disorders and traits. In this review, we summarize and interpret the existing literature on the genetic architecture of these comorbidities based on hypothesis-generating approaches. Quantitative genetic studies indicate that genetic factors play a substantial role in the observed co-occurrence of ADHD with many different disorders and traits. Molecular genetic correlations derived from genome-wide association studies and results of studies based on polygenic risk scores confirm the general pattern but provide effect estimates that are smaller than those from twin studies. The identification of the specific genetic variants and biological pathways underlying co-occurrence using genome-wide approaches is still in its infancy. The first analyses of causal inference using genetic data support causal relationships between ADHD and comorbid disorders, although bidirectional effects identified in some instances point to complex relationships. While several issues in the methodology and inferences from the results are still to be overcome, this review shows that the co-occurrence of ADHD with many psychiatric disorders and traits is genetically interpretable.</p
Genetic Architecture of ADHD and Overlap With Other Psychiatric Disorders And Cognition-Related Phenotypes
Attention-deficit/hyperactivity disorder (ADHD) co-occurs with many other psychiatric disorders and traits. In this review, we summarize and interpret the existing literature on the genetic architecture of these comorbidities based on hypothesis-generating approaches. Quantitative genetic studies indicate that genetic factors play a substantial role in the observed co-occurrence of ADHD with many different disorders and traits. Molecular genetic correlations derived from genome-wide association studies and results of studies based on polygenic risk scores confirm the general pattern but provide effect estimates that are smaller than those from twin studies. The identification of the specific genetic variants and biological pathways underlying co-occurrence using genome-wide approaches is still in its infancy. The first analyses of causal inference using genetic data support causal relationships between ADHD and comorbid disorders, although bidirectional effects identified in some instances point to complex relationships. While several issues in the methodology and inferences from the results are still to be overcome, this review shows that the co-occurrence of ADHD with many psychiatric disorders and traits is genetically interpretable.</p
Genetic Architecture of ADHD and Overlap With Other Psychiatric Disorders And Cognition-Related Phenotypes
Attention-deficit/hyperactivity disorder (ADHD) co-occurs with many other psychiatric disorders and traits. In this review, we summarize and interpret the existing literature on the genetic architecture of these comorbidities based on hypothesis-generating approaches. Quantitative genetic studies indicate that genetic factors play a substantial role in the observed co-occurrence of ADHD with many different disorders and traits. Molecular genetic correlations derived from genome-wide association studies and results of studies based on polygenic risk scores confirm the general pattern but provide effect estimates that are smaller than those from twin studies. The identification of the specific genetic variants and biological pathways underlying co-occurrence using genome-wide approaches is still in its infancy. The first analyses of causal inference using genetic data support causal relationships between ADHD and comorbid disorders, although bidirectional effects identified in some instances point to complex relationships. While several issues in the methodology and inferences from the results are still to be overcome, this review shows that the co-occurrence of ADHD with many psychiatric disorders and traits is genetically interpretable.</p
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