A molecular dynamics model to measure forces between cellulose fibril surfaces: on the effect of non-covalent polyelectrolyte adsorption

This study describes the development of representative models of cellulose fibril surface (CFS) as a first approximation to the study of the molecular interactions that are developed between cellulose fibres. In order to assess its sensitivity and representativeness towards the main factors affecting the bonding properties at the fibre scale, these models were non-covalently surface modified with two types of polyelectrolytes, sodium carboxymethyl cellulose (CMC–ONa) and a cationic polyacrylamide (CPAM). From the analysis of pair correlation functions (g(r)) it was possible to assess the main interactions of adsorption of polyelectrolytes towards the (1–10) hydrophilic cellulose, which were due to electrostatic interactions coupled with hydrogen bonding. Besides, the bond strength between fibril surfaces through the (100) hydrophobic surface was calculated from pull out simulations (using steered molecular dynamics). Using a rate of change of force of 0.159 nN ps-1, the calculated bond strength for the neat CFS model (nanometer scale) was two to three orders of magnitude higher than the experimental values observed at the fibre scale (micrometer scale). The results for the polyelectrolyte modified setups supported the validity of the CFS models to reproduce the expected behavior of inter-fibre joints in terms of the specific bond strength and the relative bonded area at the fibre scale in cellulose materials, and thereby the CFS models are a suitable complement, in conjunction with other techniques, for the systematic study of the effect (in qualitative terms) of chemical or physical factors on the bond strength properties of cellulosic materials. Graphical abstract: [Figure not available: see fulltext.]

Effects of Graphene Oxidation on Interaction Energy and Interfacial Thermal Conductivity of Polymer Nanocomposite: A Molecular Dynamics Approach

Interfacial characteristics of polymer nanocomposites represent a crucial aspect to understand their global properties and to evaluate the interaction between nanofillers and matrix. In this work we used a molecular dynamics (MD) approach to characterize the interfacial region at the atomistic scale of graphene-based polymer nanocomposites. Three different polymer matrixes were considered, polylactic acid (PLA), polypropylene (PP) and epoxy resin (EPO), which were reinforced with three types of graphene fillers: pristine graphene (G), graphene oxide (GO) and reduced graphene oxide (rGO). In particular, the compatibility of the nanofillers in polymer matrixes were evaluated in terms of the interaction energy, while the interfacial thermal resistance (Kapitza resistance) between matrices and fillers was calculated with a nonequilibrium molecular dynamics (NEMD) method. Results showed that the oxidation degree plays an important role on the studied properties of the interfacial region. In particular, it was observed that the Kapitza resistance is decreased in the oxidized graphene (GO and rGO), while interaction energy depended on the polarity of the polymer matrix molecules and the contribution of the Coulombic component

Decreased Alertness Reconfigures Cognitive Control Networks

Humans' remarkable capacity to flexibly adapt their behavior based on rapid situational changes is termed cognitive control. Intuitively, cognitive control is thought to be affected by the state of alertness; for example, when drowsy, we feel less capable of adequately implementing effortful cognitive tasks. Although scientific investigations have focused on the effects of sleep deprivation and circadian time, little is known about how natural daily fluctuations in alertness in the regular awake state affect cognitive control. Here we combined a conflict task in the auditory domain with EEG neurodynamics to test how neural and behavioral markers of conflict processing are affected by fluctuations in alertness. Using a novel computational method, we segregated alert and drowsy trials from two testing sessions and observed that, although participants (both sexes) were generally sluggish, the typical conflict effect reflected in slower responses to conflicting information compared with nonconflicting information, as well as the moderating effect of previous conflict (conflict adaptation), were still intact. However, the typical neural markers of cognitive control—local midfrontal theta-band power changes—that participants show during full alertness were no longer noticeable when alertness decreased. Instead, when drowsy, we found an increase in long-range information sharing (connectivity) between brain regions in the same frequency band. These results show the resilience of the human cognitive control system when affected by internal fluctuations of alertness and suggest that there are neural compensatory mechanisms at play in response to physiological pressure during diminished alertness

On an efficient k-step iterative method for nonlinear equations

[EN] This paper is devoted to the construction and analysis of an efficient k-step iterative method for nonlinear equations. The main advantage of this method is that it does not need to evaluate any high order Frechet derivative. Moreover, all the k-step have the same matrix, in particular only one LU decomposition is required in each iteration. We study the convergence order, the efficiency and the dynamics in order to motivate the proposed family. We prove, using some recurrence relations, a semilocal convergence result in Banach spaces. Finally, a numerical application related to nonlinear conservative systems is presented. (C) 2016 Elsevier B.V. All rights reserved.This work was supported in part by the project MTM2011-28636-C02-01-{01,02} of the Spanish Ministry of Science and Innovation.Amat, S.; Bermúdez, C.; Hernández-Verón, MA.; Martínez Molada, E. (2016). On an efficient k-step iterative method for nonlinear equations. Journal of Computational and Applied Mathematics. 302:258-271. https://doi.org/10.1016/j.cam.2016.02.003S25827130

Perceived health status: is obesity perceived as a risk factor and disease?

One might expect that a perception of obesity being a risk factor and disease, contributes to effective obesity prevention and management strategies. However, obesity rates continue to increase worldwide. The question arises whether obesity is truly perceived as a risk factor and a disease. This paper aims at describing perception of obesity as risk factor and disease among individuals seeking care, individuals not seeking care, the society, and different professionals having a role in the field of obesity. The paper is a reflection of the lecture on the topic that was given at the EASO's New Investigators United's Summer School 2016 in Portugal and the discussion with the new investigators and other senior speakers. Individual obese patients seeking help are very much aware of obesity being a risk factor and disease, but perceptions regarding obesity seem to be flawed among those who do not seek help for obesity. Also, misperceptions regarding obesity play a role at different levels, including society, different political levels, the fields of health care and social work, prevention organizations, and the food and marketing industry. The food and marketing industry has an enormous role in changing perceptions by the society and policy makers. Obesity rates will continue to increase as long as individuals, the society, and professionals at different levels have false interpretations of the severity of obesity. Severe action is needed against those who are playing a role in maintaining false perceptions of obesity as a risk factor and disease.- (undefined

Ascitis secundaria a chlamydia trachomatis tras procedimiento de reproducción asistida

El desarrollo de ascitis moderada o severa es infrecuente tras una enfermedad inflamatoria pélvica por Chlamydia trachomatis, una de las principales causas de infección de transmisión sexual a nivel mundial. Caso clínico: Paciente de 29 años que tras aborto diferido (gestación tras inseminación artificial) que inicia a las seis semanas con cuadro de dolor abdominal inespecífico y ascitis de predominio linfocitario. El diagnostico se realizo mediante PCR (Werfen®) tanto el liquido ascítico como en exudado endocervical. La paciente recibió tratamiento antibiótico con doxiciclina. Conclusión: Las enfermedades de transmisión sexual deben ser consideradas cuando se realiza un diagnóstico diferencial de una mujer sexualmente activa con dolor abdominal y ascitis, instaurar tratamiento antibiótico y evitar pruebas e intervenciones quirúrgicas innecesarias. The development of moderate or severe ascites is infrequent after a pelvic inflammatory disease from Chlamydia trachomatis, one of the main causes of sexually transmitted infection worldwide. Clinical case: A 29-year-old patient who, after a delayed abortion (gestation after artificial insemination), started at six weeks with symptoms of non-specific abdominal pain and predominantly lymphocytic ascites. The diagnosis is made by PCR (Werfen®) both the ascitic fluid and the endocervical exudate. The patient received antibiotic treatment with doxycycline. Conclusion: Sexually transmitted diseases should be considered when making a differential diagnosis of a sexually activated woman with abdominal pain and ascites. Establishing antibiotic treatment, and avoiding unnecessary tests and surgical treatments

On the p-length of some finite p-soluble groups

The main aim of this paper is to give structural information of a finite group of minimal order belonging to a subgroup-closed class of finite groups and whose p-length is greater than 1, p a prime number. Alternative proofs and improvements of recent results about the influence of minimal p-subgroups on the p-nilpotence and p-length of a finite group arise as consequences of our study

Identification of distinct pathological signatures induced by patient-derived -synuclein structures in nonhuman primates

©. This manuscript version is made available under the CC BY-NC 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ This document is the Submitted, Accepted, Published, version of a Published Work that appeared in final form in Science Advances To access the final edited and published work see http://dx.doi.org/10.5281/zenodo.1240558Dopaminergic neuronal cell death, associated with intracellular -synuclein (-syn)–rich protein aggregates [termed “Lewy bodies” (LBs)], is a well-established characteristic of Parkinson’s disease (PD). Much evidence, accumulated from multiple experimental models, has suggested that -syn plays a role in PD pathogenesis, not only as a trigger of pathology but also as a mediator of disease progression through pathological spreading. Here, we have used a machine learning–based approach to identify unique signatures of neurodegeneration in monkeys induced by distinct -syn pathogenic structures derived from patients with PD. Unexpectedly, our results show that, in nonhuman primates, a small amount of singular -syn aggregates is as toxic as larger amyloid fibrils present in the LBs, thus reinforcing the need for preclinical research in this species. Furthermore, our results provide evidence supporting the true multifactorial nature of PD, as multiple causes can induce a similar outcome regarding dopaminergic neurodegeneration

Background discrimination with a Micromegas detector prototype and veto system for BabyIAXO

In this paper we present measurements performed with a Micromegas X-ray detector setup. The detector is a prototype in the context of the BabyIAXO helioscope, which is under construction to search for an emission of the hypothetical axion particle from the sun. An important component of such a helioscope is a low background X-ray detector with a high efficiency in the 1-10 keV energy range. The goal of the measurement was to study techniques for background discrimination. In addition to common techniques we used a multi-layer veto system designed to tag cosmogenic neutron background. Over an effective time of 52 days, a background level of $8.6 \times 10^{-7}\,\text{counts keV}^{-1}\,\text{cm}^{-2} \, \text{s}^{-1}$ was reached in a laboratory at above ground level. This is the lowest background level achieved at surface level. In this paper we present the experimental setup, show simulations of the neutron-induced background, and demonstrate the process to identify background signals in the data. Finally, prospects to reach lower background levels down to $10^{-7} \, \text{counts keV}^{-1} \, \text{cm}^{-2} \, \text{s}^{-1}$ will be discussed