Temperature and ph responsive behaviour of antifouling zwitterionic mesoporous silica nanoparticles.

[EN] Zwitterionic brush grafting is considered a serious strategy for surface modification on mesoporous silica nanoparticles (MSN) and a prominent alternative to polyethylene glycol films for antifouling applications. In this study, the solution behavior of poly(sulfobetaine methacrylate) (pSBMA) polymer brushes grafted on MSN (95 +/- 15nm particle diameter, 2.8nm pore size) was evaluated. The layers increased their hydrodynamic diameter (d(H)) with increasing temperature, indicating a conformational change from a surface-collapsed state to a fully solvated brush. This development was marked by a transition temperature, related to the molecular weight and the theoretical length of the polymer chains. Variation of d(H) with pH values was studied and a zwitterionic range of 5-9 was established where the electric charges in the molecule were balanced. Zeta potential (ZP) values for all pSBMA-MSN products were also measured. A decreasing trend of ZP with pH and an isoelectric point around 5.5-6.5 was obtained for all dispersions. Furthermore, the influence of temperature was analyzed on ZP and a directly proportional correlation was found, with increasing rates of 0.50-0.87%/degrees C. Finally, ZP variation with electrolyte concentration was determined and a range of 40-60mM of NaCl concentration was established to reach an almost zero-charge point for all nanoparticles. It was demonstrated that the solution response of pSBMA-MSN can be modulated by temperature, pH, and ionic concentration of the media. These behaviors could be used as controlled release mechanisms for the application of pSBMA-MSN as carriers in biomedicine and nanophamaceutical fields in the future. Published under license by AIP Publishing.Jose L. Gomez Ribelles acknowledges support of the Ministerio de Economia y Competitividad, MINECO (Research No. MAT2016-76039-C4-1-R). CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions, and financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund. This work was also supported by Ministerio de Ciencia, Tecnologia e Innovacion (MINCIENCIAS), Convocatoria 567 Doctorados Nacionales, and Universidad Nacional de Colombia (Grant No. DIB 201010021438). The authors acknowledge the effort of Ramon Martinez Manez, Scientific Director of the Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), and Head of the Interuniversity Research Institute for Molecular Recognition and Technological Development (IDM) at Universitat Politecnica de Valencia, where all measurements were performedBeltran-Osuna, AA.; Gómez Ribelles, JL.; Perilla, JE. (2020). Temperature and ph responsive behaviour of antifouling zwitterionic mesoporous silica nanoparticles. 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Elementos conceptuales para estudiar el comportamiento bioadhesivo en polímeros

La bioadhesión es un fenómeno interfacial que ocurre entre un material polimérico y una superficie biológica. Las interacciones entre las fases son el resultado tanto de las propiedades del polímero como de la naturaleza del sustrato.En este documento se estudian los aspectos teóricos fundamentales que permiten entender los mecanismos que se proponen para la interpretación del fenómeno desde cada una de las teorías existentes, considerando los factores que determinan el comportamiento bioadhesivo de un polímero y las características del sustrato. Finalmente se analizan las técnicas experimentales existentes para determinar la bioadhesividad en materiales poliméricos y las aplicaciones en el diseño de algunos sistemas terapéuticos farmacéuticos.The bioadhesion is an interfacial phenomenon ocurring between a polymer and a biological surface. Due to the complex nature of polymers and molecules present in the biological surfaces, many factors determine the strength and duration of the adhesion. However, the specific interactions in the polymer/biological substrate interface are governed by both, the properties of the polymer and the nature of the substrate. In this document the theoretical fundamentals of the current mechanisms that have been proposed to explain bioadhesion are reviewed. Also, the main factors determining the bioadhesive behavior of a polymer and the properties of the substrate are discussed. Finally, the experimental techniques to evaluate the bioadhesion in polymers are analyzed, and the applications in some therapeutic pharmaceutical systems presente

Silica phase formed by sol-gel reaction in the nano- and micro-pores of a polymer hydrogel

Hybrid composites consisting in a hydrogel matrix with silica micro- and nano-particle reinforcement were produced and characterized. The strategy proposed here to obtain them consisted in a two-step synthesis being the polymer network formation the first step. Porous poly(hydroxyethyl acrylate) hydrogel network was produced by radical polymerization of the monomer diluted in different amounts of ethanol. Polymeric microstructure drives the absorption of a silica precursor solution and the further distribution of the inorganic phase that is formed in situ. A fraction of the resulting silica phase occupies the pores and the other part is in the form of nanoparticles dispersed in the polymer phase. Composites with silica content up to ~ 60% by weight were obtained. Silica phase is continuous and samples maintain their integrity after eliminating the organic phase by pyrolysis. Dependence of hybrid microstructure in compliance, water sorption capacity, bioactivity and the effect of silica content in polymer segmental mobility were assessed.CEPB acknowledges the economic support of COOPEN agreement in the progress of the present work. JLGR acknowledges the support of the Spanish Ministry of Education through project No. MAT2010-21611-C03-01 (including the FEDER financial support) and from Generalitat Valenciana, ACOMP/2012/075 project. The support of the Instituto de Salud Carlos III (ISCIII) through the CIBER Initiative of the Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) is also acknowledged. Authors want to thank the technical support of the Universitat Politecnica de Valencia's Microscopy Service.Plazas Bonilla, CE.; Gómez-Tejedor, JA.; Perilla, JE.; Gómez Ribelles, JL. (2013). Silica phase formed by sol-gel reaction in the nano- and micro-pores of a polymer hydrogel. Journal of Non-Crystalline Solids. 379:12-20. https://doi.org/10.1016/j.jnoncrysol.2013.07.018S122037

EPOC Ocupacional: Una revisión sistemática.

according to the WHO in 2012, three million people died of chronic obstructive pulmonary disease -COPD-, which represented 6% of deaths that year. The ILO recommendation 194/2010 established some economic activities such as occupational risk factors for it. Objective: No information globally about the disease nationwide. Methodology: The literature of documents contained in internationally recognized institutions were consulted how Scielo y PubMed. Results: COPD's main risk factor exposure to smoke snuff, but occupational hazards are another important group in the genesis of this pathology. The literature reports that workers with a history of consumption of snuff, exposed to occupational risk factors, the presence of COPD is increased, compared with smokers workers no exposed to these occupational risk factors. There is national and international recognition of the relationship of the onset of COPD with specific trades and economic activities. Conclusions: COPD is an occupational problem related to industrialization and its consequences have worldwide scope. The state and industry must find solutions, to be less polluting sources of exposure, promptly identifying occupational risk factors and educating workers on prevention, discouraging exposure to cigarette smoke as a negative prognostic factor for the development of occupational COPD.según la OMS en 2012, 3 millones de personas fallecieron por la enfermedad pulmonar obstructiva crónica -EPOC-, lo que significó el 6% de muertes ese año. La recomendación 194/2010 de la OIT estableció algunas actividades económicas Objetivo: Determinar los factores de riesgo ocupacional para dicha enfermedad. Metodología: Consulta de bibliografía de bases de datos internacionales como Scielo y PubMed. Resultados: El EPOC tiene como principal factor de riesgo la exposición al humo de tabaco, pero los riesgos ocupacionales representan otro importante grupo en la génesis de esta patología. Se reporta que en trabajadores con historia de consumo de tabaco y expuestos a factores de riesgo ocupacional, se aumentó la presencia de EPOC, en comparación con trabajadores fumadores no expuestos a dichos factores de riesgo laboral. Existe reconocimiento nacional e internacional sobre la relación de EPOC con actividades económicas y oficios específicos. Conclusiones: la EPOC ocupacional es un problema relacionado con la industrialización y sus consecuencias tienen alcances internacionales. El estado y la industria deben buscar soluciones, para encontrar fuentes de exposición menos contaminantes, identificando oportunamente los factores de riesgo ocupacional y educando a los trabajadores en prevención, desestimulando el consumo de cigarrillo, como factor negativo del pronóstico para el desarrollo de EPOC ocupacional

Hickson-like compact groups inhabiting different environments

Although Compact Groups of galaxies (CGs) have been envisioned as isolated extremely dense structures in the Universe, it is accepted today that many of them could be not as isolated as thought. In this work, we study Hickson-like CGs identified in the Sloan Digital Sky Survey Data Release 16 to analyse these systems and their galaxies when embedded in different cosmological structures. To achieve this goal, we identify several cosmological structures where CGs can reside: Nodes of filaments, Loose Groups, Filaments and cosmic Voids. Our results indicate that 45 per cent of CGs do not reside in any of these structures, i.e., they can be considered non-embedded or isolated systems. Most of the embedded CGs are found inhabiting Loose Groups and Nodes, while there are almost no CGs residing well inside cosmic Voids. Some physical properties of CGs vary depending on the environment they inhabit. CGs in Nodes show the largest velocity dispersions, the brightest absolute magnitude of the first-ranked galaxy, and the smallest crossing times, while the opposite occurs in Non-Embedded CGs. When comparing galaxies in all the environments and galaxies in CGs, CGs show the highest fractions of red/early-type galaxy members in most of the absolute magnitudes ranges. The variation between galaxies in CGs inhabiting one or another environment is not as significant as the differences caused by belonging or not to a CG. Our results suggest a plausible scenario for galaxy evolution in CGs in which both, large-scale and local environments play essential roles.Comment: 16 pages, 9 figures, 1 table, accepted for publication in MNRA

Ictal propagation of high frequency activity is recapitulated in interictal recordings: effective connectivity of epileptogenic networks recorded with intracranial EEG

Seizures are increasingly understood to arise from epileptogenic networks across which ictal activity is propagated and sustained. In patients undergoing invasive monitoring for epilepsy surgery, high frequency oscillations have been observed within the seizure onset zone during both ictal and interictal intervals. We hypothesized that the patterns by which high frequency activity is propagated would help elucidate epileptogenic networks and thereby identify network nodes relevant for surgical planning. Intracranial EEG recordings were analyzed with a multivariate autoregressive modeling technique (short-time direct directed transfer function--SdDTF), based on the concept of Granger causality, to estimate the directionality and intensity of propagation of high frequency activity (70-175 Hz) during ictal and interictal recordings. These analyses revealed prominent divergence and convergence of high frequency activity propagation at sites identified by epileptologists as part of the ictal onset zone. In contrast, relatively little propagation of this activity was observed among the other analyzed sites. This pattern was observed in both subdural and depth electrode recordings of patients with focal ictal onset, but not in patients with a widely distributed ictal onset. In patients with focal ictal onsets, the patterns of propagation recorded during pre-ictal (up to 5 min immediately preceding ictal onset) and interictal (more than 24h before and after seizures) intervals were very similar to those recorded during seizures. The ability to characterize epileptogenic networks from interictal recordings could have important clinical implications for epilepsy surgery planning by reducing the need for prolonged invasive monitoring to record spontaneous seizures

Automated classification of eclipsing binary systems in the VVV Survey

With the advent of large-scale photometric surveys of the sky, modern science witnesses the dawn of big data astronomy, where automatic handling and discovery are paramount. In this context, classification tasks are among the key capabilities a data reduction pipeline must possess in order to compile reliable data sets, to accomplish data processing with an efficiency level impossible to achieve by means of detailed processing and human intervention. The VISTA Variables of the Vía Láctea Survey, in the southern part of the Galactic disc, comprises multiepoch photometric data necessary for the potential discovery of variable objects, including eclipsing binary systems (EBs). In this study, we use a recently published catalogue of one hundred EBs, classified by fine-tuning theoretical models according to contact, detached, or semidetached classes belonging to the tile d040 of the VVV. We describe the method implemented to obtain a supervised machine-learning model, capable of classifying EBs using information extracted from the light curves of variable object candidates in the phase space from tile d078. We also discuss the efficiency of the models, the relative importance of the features and the future prospects to construct an extensive data base of EBs in the VVV survey.Fil: Daza Perilla, Ingrid Vanessa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Gramajo, Luciana Veronica. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Lares Harbin Latorre, Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Palma, Tali. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Ferreira Lopes, C. E.. Universidad de Atacama.; ChileFil: Minniti, D.. Universidad Andrés Bello; ChileFil: Claria Olmedo, Juan Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentin

Directional Derivative-Based Method for Quasi-Stationary Voltage Support Analysis of Single-Infeed VSC-HVDC units

This study presents an investigation of the impact of the quasi-stationary voltage support provided by a voltage source converter (VSC) connected to a single point of a power system. Based on the directional derivative concept, an analytical method is developed to quantify the sensitivities of the AC bus voltage with respect to the VSC reactive power control modes. Based on a real case study, it is shown that the method applies to VSC units that are part of VSC-HVDC systems, which can operate in a point-to-point or multi-terminal configuration. Time-domain simulations are performed to verify the findings from the application of the analytical method on a reduced size power system.</p

Prolonged exposure for the treatment of Spanish-speaking Puerto Ricans with posttraumatic stress disorder: a feasibility study

<p>Abstract</p> <p>Background</p> <p>Most of the empirical studies that support the efficacy of prolonged exposure (PE) for treating posttraumatic stress disorder (PTSD) have been conducted on white mainstream English-speaking populations. Although high PTSD rates have been reported for Puerto Ricans, the appropriateness of PE for this population remains unclear. The purpose of this study was to examine the feasibility of providing PE to Spanish speaking Puerto Ricans with PTSD. Particular attention was also focused on identifying challenges faced by clinicians with limited experience in PE. This information is relevant to help inform practice implications for training Spanish-speaking clinicians in PE.</p> <p>Results</p> <p>Fourteen patients with PTSD were randomly assigned to receive PE (n = 7) or usual care (UC) (n = 7). PE therapy consisted of 15 weekly sessions focused on gradually confronting and emotionally processing distressing trauma-related memories and reminders. Five patients completed PE treatment; all patients attended the 15 sessions available to them. In UC, patients received mental health services available within the health care setting where they were recruited. They also had the option of self-referring to a mental health provider outside the study setting. The Clinician-Administered PTSD Scale (CAPS) was administered at baseline, mid-treatment, and post-treatment to assess PTSD symptom severity. Treatment completers in the PE group demonstrated significantly greater reductions in PTSD symptoms than the UC group. Forty percent of the PE patients showed clinically meaningful reductions in PTSD symptoms from pre- to post-treatment.</p> <p>Conclusions</p> <p>PE appears to be viable for treating Puerto Rican Spanish-speaking patients with PTSD. This therapy had good patient acceptability and led to improvements in PTSD symptoms. Attention to the clinicians' training process contributed strongly to helping them overcome the challenges posed by the intervention and increased their acceptance of PE.</p