958 research outputs found
The contribution of the Chirality-Induced Spin Selectivity (CISS) effect to the dispersion interaction between chiral molecules
Dispersion interactions are one of the components of van der Waals forces,
which play a key role in the understanding of intermolecular interactions in
many physical, chemical and biological processes. The theory of dispersion
forces was developed by London in the early years of quantum mechanics.
However, it was only in the 1960s that it was recognized that for molecules
lacking an inversion center such as chiral and helical molecules, there are
chirality-sensitive corrections to the dispersion forces proportional to the
rotatory power known from the theory of circular dichroism and with the same
distance scaling law R-6 as the London energy. The discovery of the
Chirality-Induced Spin Selectivity (CISS) effect in recent years has led to an
additional twist in the study of chiral molecular systems, showing a close
relation between spin and molecular geometry. Motivated by it, we propose in
this investigation that there may exist additional contributions to the
dispersion energy related to intermolecular, induced spin-orbit (ISOC)
interactions. Within a second-order perturbative approach, these forces
manifest as an effective intermolecular spin-spin exchange interaction.
Although they are weaker than the standard London forces, the ISOC interactions
turn out to be nevertheless not negligible and display the same R
distance scaling. Our results suggest that classical force field descriptions
of van-der Waals interactions may require additional modifications to include
the effects discussed here.Comment: 21 pages, 2 figure
Ga+, In+ and Tl+ Impurities in Alkali Halide Crystals: Distortion Trends
A computational study of the doping of alkali halide crystals (AX: A = Na, K;
X = Cl, Br) by ns2 cations (Ga+, In+ and Tl+) is presented. Active clusters of
increasing size (from 33 to 177 ions) are considered in order to deal with the
large scale distortions induced by the substitutional impurities. Those
clusters are embedded in accurate quantum environments representing the
surrounding crystalline lattice. The convergence of the distortion results with
the size of the active cluster is analyced for some selected impurity systems.
The most important conclusion from this study is that distortions along the
(100) and (110) crystallographic directions are not independent. Once a
reliable cluster model is found, distortion trends as a function of impurity,
alkali cation and halide anion are identified and discussed. These trends may
be useful when analycing other cation impurities in similar host lattices.Comment: LaTeX file. 7 pages and 2 pictures. Accepted for publication in J.
Chem. Phy
Local Detection of Quantum Correlations with a Single Trapped Ion
As one of the most striking features of quantum mechanics, quantum
correlations are at the heart of quantum information science. Detection of
correlations usually requires access to all the correlated subsystems. However,
in many realistic scenarios this is not feasible since only some of the
subsystems can be controlled and measured. Such cases can be treated as open
quantum systems interacting with an inaccessible environment. Initial
system-environment correlations play a fundamental role for the dynamics of
open quantum systems. Following a recent proposal, we exploit the impact of the
correlations on the open-system dynamics to detect system-environment quantum
correlations without accessing the environment. We use two degrees of freedom
of a trapped ion to model an open system and its environment. The present
method does not require any assumptions about the environment, the interaction
or the initial state and therefore provides a versatile tool for the study of
quantum systems.Comment: 6 Pages, 5 Figures + 6 Pages, 1 Figure of Supplementary Materia
Bioclimatological mapping tackling uncertainty propagation: application to mainland Portugal
We present a bioclimatological diagnosis of mainland Portugal, namely the thermotype and ombrotype maps
following Rivas-Martínez’s worldwide bioclimatic classicantly lower than those produced by the
former methodological framework.info:eu-repo/semantics/publishedVersio
Plants Probiotics as a Tool to Produce Highly Functional Fruits: The Case of Phyllobacterium and Vitamin C in Strawberries
10 páginas, 1 tabla, 1 figuraThe increasing interest in the preservation of the environment and the health of consumers
is changing production methods and food consumption habits. Functional foods are increasingly demanded by consumers because they contain bioactive compounds involved in health protection. In this sense biofertilization using plant probiotics is a reliable alternative to the use of chemical fertilizers, but there are few studies about the effects of plant probiotics on the yield of functional fruits and, especially, on the content of bioactive compounds. In the present work we reported that a strain of genus Phyllobacterium able to produce biofilms and to colonize strawberry roots is able to increase the yield and quality of strawberry plants. In addition, the fruits from plants inoculated with this strain have significantly higher content in vitamin C, one of the most interesting bioactive compounds in strawberries. Therefore the use of selected plant probiotics benefits the environment and human health without agronomical losses, allowing the production of highly functional foods.This work was granted by “Junta de Castilla y León” (Regional Government, Grant SA183A11-2) and MINECO (Central Government, Grant AGL2011-29227). Paula García-Fraile is
recipient of a postdoctoral researcher contract from
Academy of Sciences of the Czech Republic. José
David Flores-Félix was supported by a fellowship of
Salamanca University. Marta Marcos García was supported by a fellowship of Fundación Miguel Casado San José. Luís R. Silva is grateful to the financial support from the European Union (FEDER
funds through COMPETE) and National Funds (FCT,
Fundação para a Ciência e Tecnologia) through
project Pest-C/EQB/LA0006/2013 and from the
European Union (FEDER funds) under the framework
of QREN through Project NORTE-07-0124-FEDER-
000069.Peer reviewe
New molecular approaches in adipogenesis regulation: The connexin 43 role
Indexación: Scopus; Redalyc.La prevalencia de la obesidad a nivel mundial se ha incrementado
rápidamente durante los últimos años debido principalmente
a los cambios en el estilo de vida de la población
con un aumento significativo en el consumo de energía y disminución
de los niveles de actividad física. Es por esto que
la comunidad científica está interesada en comprender de
forma más profunda los mecanismos que regulan la fisiopatología
de la obesidad. Dentro de los diferentes blancos de
estudio se encuentra la adipogénesis, cuyo entendimiento es
fundamental para comprender el desarrollo de la obesidad y
las patologías asociadas a esta. Recientemente ha surgido
importantes evidencias que involucran a la proteína de canales
de “Gap Junction” conexina 43 (Cx43) en la regulación
de los procesos relacionados con adipogénesis, cuyo papel
es básicamente anti-adipogénico, sin embargo, nuevas funciones
de Cx43 en la regulación de la formación del tejido
adiposo siguen descubriéndose.The global prevalence of obesity has been increased rapidly
over the past few years mainly due to changes in the lifestyle
of the population with a significant increase in energy
consumption and decreased levels of physical activity. As a
result, the scientific community is interested in a deeper understanding
of the mechanisms that regulate the pathophysiology
of obesity. In this context, adipogenesis process is an
important target of study to understand the obesity and associated
pathologies. Recently has been emerged important
evidence that involve gap junction channel protein connexin
43 (Cx43) in the regulation of processes related to adipogenesis,
whose role is fundamentally anti-adipogenic. However,
new functions of Cx43 in the regulation of adipose tissue
function also continued to emerge.http://www.redalyc.org/articulo.oa?id=5594990800
Calculation of The Band Gap Energy and Study of Cross Luminescence in Alkaline-Earth Dihalide Crystals
The band gap energy as well as the possibility of cross luminescence
processes in alkaline-earth dihalide crystals have been calculated using the ab
initio Perturbed-Ion (PI) model. The gap is calculated in several ways: as a
difference between one-electron energy eigenvalues and as a difference between
total energies of appropriate electronic states of the crystal, both at the HF
level and with inclusion of Coulomb correlation effects. In order to study the
possibility of ocurrence of cross luminescence in these materials, the energy
difference between the valence band and the upmost core band for some
representative crystals has been calculated. Both calculated band gap energies
and cross luminescence predictions compare very well with the available
experimental results.Comment: LaTeX file containing 8 pages plus 1 postscript figure. Final version
accepted for publication in The Journal of the Physical Society of Japan. It
contains a more complete list of references, as well as a more detailed
comparison with previous theoretical investigations on the subjec
Interplay between SUMOylation and NEDDylation regulates RPL11 localization and function
The ribosomal protein L11 (RPL11) integrates different types of stress into a p53-mediated response. Here, we analyzed the impact of the ubiquitin-like protein SUMO on the RPL11-mouse double-minute 2 homolog-p53 signaling. We show that small ubiquitin-related modifier (SUMO)1 and SUMO2 covalently modify RPL11. We find that SUMO negatively modulates the conjugation of the ubiquitin-like protein neural precursor cell-expressed developmentally downregulated 8 (NEDD8) to RPL11 and promotes the translocation of the RP outside of the nucleoli. Moreover, the SUMO-conjugating enzyme, Ubc9, is required for RPL11-mediated activation of p53. SUMOylation of RPL11 is triggered by ribosomal stress, as well as by alternate reading frame protein upregulation. Collectively, our data identify SUMO protein conjugation to RPL11 as a new regulator of the p53-mediated cellular response to different types of stress and reveal a previously unknown SUMO-NEDD8 interplay.-El Motiam, A., Vidal, S., de la Cruz-Herrera, C. F., Da Silva-Alvarez, S., Baz-Martinez, M., Seoane, R., Vidal, A., Rodriguez, M. S., Xirodimas, D. P., Carvalho, A. S., Beck, H. C., Matthiesen, R., Collado, M., Rivas, C. Interplay between SUMOylation and NEDDylation regulates RPL11 localization and function
Clocks do not tick in unison: isolation of Clock and vrille shed new light on the clockwork model of the sand fly Lutzomyia longipalpis
Ab Initio Calculation of the Lattice Distortions induced by Substitutional Ag- and Cu- Impurities in Alkali Halide Crystals
An ab initio study of the doping of alkali halide crystals (AX: A = Li, Na,
K, Rb; X = F, Cl, Br, I) by ns2 anions (Ag- and Cu-) is presented. Large active
clusters with 179 ions embedded in the surrounding crystalline lattice are
considered in order to describe properly the lattice relaxation induced by the
introduction of substitutional impurities. In all the cases considered, the
lattice distortions imply the concerted movement of several shells of
neighbors. The shell displacements are smaller for the smaller anion Cu-, as
expected. The study of the family of rock-salt alkali halides (excepting CsF)
allows us to extract trends that might be useful at a predictive level in the
study of other impurity systems. Those trends are presented and discussed in
terms of simple geometric arguments.Comment: LaTeX file. 8 pages, 3 EPS pictures. New version contains
calculations of the energy of formation of the defects with model clusters of
different size
- …