Coarse Molecular-Dynamics Determination of the Onset of Structural Transitions: Melting of Crystalline Solids

Using a coarse molecular-dynamics (CMD) approach with an appropriate choice of coarse variable (order parameter), we map the underlying effective free-energy landscape for the melting of a crystalline solid. Implementation of this approach provides a means for constructing effective free-energy landscapes of structural transitions in condensed matter. The predictions of the approach for the thermodynamic melting point of a model silicon system are in excellent agreement with those of ''traditional'' techniques for melting-point calculations, as well as with literature values

Liquid-vapor equilibria and interfacial properties of n-alkanes and perfluoroalkanes by molecular simulation

A molecular dynamics study is presented to assess the performance of a united-atom model in the prediction of liquid-vapor interfacial properties for short-chain perfluoroalkanes and their alkane counterparts. In particular, the ability of this model to discriminate between the surface-energy values of these two types of compounds was investigated over a wide temperature range corresponding to the liquid-vapor region. Comparisons with available experimental data and surface-tension predictions given by other force-field parameterizations, including those based on the more computationally demanding all-atom method, were performed to gauge the viability of this model. It was found that the model used in this study captures qualitatively the expected behavior of surface energy between alkanes and perfluoroalkanes and yields values that are in excellent agreement with experimental data, especially in the high-temperature limit as the critical temperature is approached

Coarse molecular-dynamics analysis of stress-induced structural transitions in crystals

We present a coarse molecular-dynamics (CMD) approach for the study of stress-induced structural transformations in crystals at finite temperatures. The method relies on proper choice of a coarse variable (order parameter, observable), which parameterizes the changes in effective free energy during the transformation. Results are reported for bcc-to-hcp lattice transitions under pressure. We explore coarse-variable space to reconstruct an effective free-energy landscape quantifying the relative stability of different metastable basins and locate the onset, at a critical pressure, of the bcc-to-hcp transformation.Comment: 3 page

Greater flamingos Phoenicopterus roseus are partial capital breeders

Capital breeding refers to a strategy in which birds use body stores for egg formation, whereas income breeders obtain all resources for egg formation at breeding sites. Capital breeding should occur more in large-bodied species because the relative cost of carrying stores for egg formation becomes smaller with increasing body size. Based on a comparison between stable isotopes of carbon and nitrogen in potential prey at wintering sites and eggs, we examined whether greater flamingos use nutrients stored earlier in the year for egg production. Our results suggest that the greater flamingo is a partial income breeder, since prey for egg formation were obtained both in overwintering sites and at the breeding site. This may be because there are selective pressures for nesting females to lay soon after arriving at the breeding site, which may be facilitated by arriving at the breeding site with developed ovarian follicles. © 2011 The Authors.Peer Reviewe

Histologic and histomorphometric evaluation of a new bioactive liquid bbl on implant surface: a preclinical study in foxhound dogs

Background: bioactive chemical surface modifications improve the wettability and osse-ointegration properties of titanium implants in both animals and humans. The objective of this animal study was to investigate and compare the bioreactivity characteristics of titanium implants (BLT) pre‐treated with a novel bone bioactive liquid (BBL) and the commercially available BLT‐SLA active. Methods: forty BLT‐SLA titanium implants were placed in in four foxhound dogs. Animals were divided into two groups (n = 20): test (BLT‐SLA pre‐treated with BBL) and control (BLT‐SLA active) implants. The implants were inserted in the post extraction sockets. After 8 and 12 weeks, the animals were sacrificed, and mandibles were extracted, containing the implants and the surrounding soft and hard tissues. Bone‐to‐implant contact (BIC), inter‐thread bone area percentage (ITBA), soft tissue, and crestal bone loss were evaluated by histology and histomorphometry. Results: all animals were healthy with no implant loss or inflammation symptoms. All implants were clinically and histologically osseo‐integrated. Relative to control groups, test implants demon-strated a significant 1.5‐ and 1.7‐fold increase in BIC and ITBA values, respectively, at both assessment intervals. Crestal bone loss was also significantly reduced in the test group, as compared with controls, at week 8 in both the buccal crests (0.47 ± 0.32 vs 0.98 ± 0.51 mm, p < 0.05) and lingual crests (0.39* ± 0.3 vs. 0.89 ± 0.41 mm, p < 0.05). At week 12, a pronounced crestal bone loss improvement was observed in the test group (buccal, 0.41 ± 0.29 mm and lingual, 0.54 ± 0.23 mm). Tissue thickness showed comparable values at both the buccal and lingual regions and was significantly improved in the studied groups (0.82–0.92 mm vs. 33–48 mm in the control group). Conclusions: Relative to the commercially available BLT‐SLA active implants, BLT‐SLA pre‐treated with BBL showed improved histological and histomorphometric characteristics indicating a reduced titanium surface roughness and improved wettability, promoting healing and soft and hard tissue regeneration at the implant site.This research was funded by: Biointelligent Technology Systems SL, Barcelona, Spain

A multistep Steffensen-type method for solving nonlinear systems of equations

[EN] This paper is devoted to the semilocal analysis of a high-order Steffensen-type method with frozen divided differences. The methods are free of bilinear operators and derivatives, which constitutes the main limitation of the classical high-order iterative schemes. Although the methods are more demanding, a semilocal convergence analysis is presented using weaker conditions than the classical Steffensen method.This work was supported supported in part by by Programa de Apoyo a la investigación de la fundación Séneca-Agencia de Ciencia y Tecnología de la Región de Murcia 19374/PI/14, by the project of Generalitat Valenciana Prometeo/2016/089 and the projects MTM2015-64382-P (MINECO/FEDER), MTM2014-52016-C2-1-P and MTM2014-52016-C2-2-P of the Spanish Ministry of Science and InnovationAmat, S.; Argyros, IK.; Busquier, S.; Hernández-Verón, MA.; Magreñán, AA.; Martínez Molada, E. (2020). A multistep Steffensen-type method for solving nonlinear systems of equations. Mathematical Methods in the Applied Sciences. 43(13):7518-7536. https://doi.org/10.1002/mma.5599S75187536431

Involvement of lipid rafts in the localization and dysfunction effect of the antitumor ether phospholipid edelfosine in mitochondria

This work is licensed under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Unported License.-- et al.Lipid rafts and mitochondria are promising targets in cancer therapy. The synthetic antitumor alkyl-lysophospholipid analog edelfosine (1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine) has been reported to target lipid rafts. Here, we have found that edelfosine induced loss of mitochondrial membrane potential and apoptosis in human cervical carcinoma HeLa cells, both responses being abrogated by Bcl-xL overexpression. We synthesized a number of new fluorescent edelfosine analogs, which preserved the proapoptotic activity of the parent drug, and colocalized with mitochondria in HeLa cells. Edelfosine induced swelling in isolated mitochondria, indicating an increase in mitochondrial membrane permeability. This mitochondrial swelling was independent of reactive oxygen species generation. A structurally related inactive analog was unable to promote mitochondrial swelling, highlighting the importance of edelfosine molecular structure in its effect on mitochondria. Raft disruption inhibited mitochondrial localization of the drug in cells and edelfosine-induced swelling in isolated mitochondria. Edelfosine promoted a redistribution of lipid rafts from the plasma membrane to mitochondria, suggesting a raft-mediated link between plasma membrane and mitochondria. Our data suggest that direct interaction of edelfosine with mitochondria eventually leads to mitochondrial dysfunction and apoptosis. These observations unveil a new framework in cancer chemotherapy that involves a link between lipid rafts and mitochondria in the mechanism of action of an antitumor drug, thus opening new avenues for cancer treatment.This work was supported by the Spanish Ministerio de Ciencia e Innovación (SAF2008-02251, BQU2003-4413 and RD06/0020/1037 from Red Temática de Investigación Cooperativa en Cáncer, Instituto de Salud Carlos III, cofunded by the Fondo Europeo de Desarrollo Regional of the European Union), Fondo de Investigación Sanitaria and European Commission (FIS-FEDER 06/0813, 08/1434, PS09/01915), European Community's Seventh Framework Programme FP7-2007-2013 (grant HEALTH-F2-2011-256986), Junta de Castilla y León (CSI052A11-2, GR15-Experimental Therapeutics and Translational Oncology Program, Biomedicine Project 2009 and Biomedicine Project 2010-2011), Fundación para la Investigación Sanitaria en Castilla-La Mancha (FISCAM, PI-2006/10) and Junta de Comunidades de Castilla-La Mancha (I1I09-0163-4002). CG is supported by the Ramón y Cajal Program from the Spanish Ministerio de Ciencia e Innovación. MF is recipient of a postdoctoral fellowship from Fondo de Investigación Sanitaria. VH is recipient of a predoctoral fellowship from the Spanish Ministerio de Ciencia e Innovación.Peer reviewe

Quail eggs in artificial nests change their coloration when exposed to ambient conditions: implication for studies on nest predation

Quail eggs have been widely used in field experiments, mainly to study factors associated with the risk of nest predation. Some shortcomings of using quail eggs in this type of study have been previously addressed (e.g., these eggs might be too big for some predators of eggs of small birds). Here, we show experimental evidence of another shortcoming of the use of these eggs in field experiments. Quail eggs exposed to sunlight rapidly faded in colour after three days, both in the visible and UV spectra, and this change was related to the amount of solar radiation received. This caused changes in the camouflage of the eggs, which may be perceived by predators with different visual systems (dichromatic, trichromatic, and tetrachromatic (for both violet- and UV-sensitive species)). Therefore, the results of field studies of nest predation using quail eggs might be questioned in those cases in which the camouflage has been altered due to the rapid changes in coloration, as this can affect the resulting predation rates. We recommend that researchers planning to use quail eggs should perform a prospective assessment of changes in coloration of eggs exposed to environmental conditions in the nest sites used by the target species.This study was funded by grant CGL2017-83518-P from Ministerio de Economia, Industria y Competitividad, Spain, with EU-ERDF financial support. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Chemically defined conditions mediate an efficient induction of dental pulp pluripotent-like stem cells into hepatocyte-like cells

Liver diseases are major causes of morbidity and mortality. Dental pulp pluripotent-like stem cells (DPPSCs) are of a considerable promise in tissue engineering and regenerative medicine as a new source of tissue-specific cells; therefore, this study is aimed at demonstrating their ability to generate functional hepatocyte-like cells in vitro. Cells were differentiated on a collagen scaffold in serum-free media supplemented with growth factors and cytokines to recapitulate liver development. At day 5, the differentiated DPPSC cells expressed the endodermal markers FOXA1 and FOXA2. Then, the cells were derived into the hepatic lineage generating hepatocyte-like cells. In addition to the associated morphological changes, the cells expressed the hepatic genes HNF6 and AFP. The terminally differentiated hepatocyte-like cells expressed the liver functional proteins albumin and CYP3A4. In this study, we report an efficient serum-free protocol to differentiate DPPSCs into functional hepatocyte-like cells. Our approach promotes the use of DPPSCs as a new source of adult stem cells for prospective use in liver regenerative medicine.This study was funded by the Universitat Internacional de Catalunya (UIC), the Agència de Gestió d’Ajuts Universitaris i de Recerca, Generalitat de Catalunya project number (SGR 1060 for MA), the Kuwait Foundation for the Advancement of Sciences (KFAS), and the Dasman Diabetes Institute under project number (RA-2013-009 for AAM). CGR, EMS, and RNT were funded by the predoctoral grant Junior Faculty award from the Obra Social, 'la Caixa' Foundation, and UIC