Self-Assembly Behavior of Amphiphilic Janus Dendrimers in Water: A Combined Experimental and Coarse-Grained Molecular Dynamics Simulation Approach

Indexación: Scopus.Acknowledgments: M.E.E.G. thank the Ph. D. scholarship (251115) from CONACyT. The authors would like to thank: Luis Elizalde-Herrera (CIQA) for his help running the NMR spectra; Gloria Macedo-Raygoza and Miguel J. Beltrán-García (UAG), for their help in the measuring of MALDI-TOF mass spectra; and Maricela Rodríguez-Nieto and Jorge Luis Menchaca (UANL), for their help with the AFM measurements. FDGN thanks to the USA Air Force Office of Scientific Research Awards.Amphiphilic Janus dendrimers (JDs) are repetitively branched molecules with hydrophilic and hydrophobic components that self-assemble in water to form a variety of morphologies, including vesicles analogous to liposomes with potential pharmaceutical and medical application. To date, the self-assembly of JDs has not been fully investigated thus it is important to gain insight into its mechanism and dependence on JDs’ molecular structure. In this study, the aggregation behavior in water of a second-generation bis-MPA JD was evaluated using experimental and computational methods. Dispersions of JDs in water were carried out using the thin-film hydration and ethanol injection methods. Resulting assemblies were characterized by dynamic light scattering, confocal microscopy, and atomic force microscopy. Furthermore, a coarse-grained molecular dynamics (CG-MD) simulation was performed to study the mechanism of JDs aggregation. The obtaining of assemblies in water with no interdigitated bilayers was confirmed by the experimental characterization and CG-MD simulation. Assemblies with dendrimersome characteristics were obtained using the ethanol injection method. The results of this study establish a relationship between the molecular structure of the JD and the properties of its aggregates in water. Thus, our findings could be relevant for the design of novel JDs with tailored assemblies suitable for drug delivery systems. © 2018 by the authors.https://www.mdpi.com/1420-3049/23/4/96

Recuperación de V y Mo de catalizadores gastados de la industria petroquímica. Parte II

En el presente trabajo se desarrollaron dos procesos para la recuperación de los metales vanadio, molibdeno y níquel contenidos en catalizadores de desecho de la industria petroquímica. El vanadio y el molibdeno son recuperados a partir de catalizadores gastados de la industria petroquímica en las formas de vanadato y molibdato de sodio por lixiviación con soluciones acuosas de NH3 o NaOH después de un tratamiento preliminar del catalizador con CS2 o solventes orgánicos. El uso de solventes reciclados permite recuperar el azufre y minimizar la contaminación atmosférica debida a las cantidades considerables de gas SO2 que se emiten. La caracterización de los productos obtenidos en cada una de las etapas de extracción y recuperación de los productos finales se llevó a cabo por las técnicas de difracción de rayos X por el método de polvos, absorción atómica y análisis termogravimétrico, simplificando así la ruta crítica de su extracción. Diferentes concentraciones de las soluciones de NH3 y NaOH y dierentes condiciones de operación fueron investigadas. Estos metales se extrajeron selectivamente por diferentes técnicas empleadas. Los resultados muestran que con un simple tratamiento del catalizador con el hidróxido de sodio y el hidróxido de amonio, que son agentes alcalinos relativamente comunes y de bajo costo, se pueden recuperar dos de los metales contenidos en mayor proporción en el catalizador, que son el vanadio en un 98% y el molibdeno en un 92% respectivamente en forma de sales, permitiendo así su posterior reutilización. El método de recuperación presentado en este trabajo resulta ser una buena alternativa para la Industria Petroquímica por ser efectivo y a la vez factible, gracias precisamente a la reutilización de estos metales, la cual representa una gran ventaja económica competitiva a nivel comercial

Surface plasmon excitation and manipulation in disordered two-dimensional nanoparticle arrays

We present experimental and numerical results of simultaneous surface plasmon polariton (SPP) excitation and in-plane manipulation with random arrays of gold nanoparticles. The recorded images were obtained by using leakage radiation microscopy (LRM) for the excitation wavelength of 633 nm and for di®erent densities of particles. The numerical model makes use of a composed analytic Green dyadic which takes into account near- and far-¯eld regions, with the latter being approximated by the part describing the scattering via excitation of SPP. The LRM optical images obtained are related to the calculated SPP intensity distributions demonstrating that the developed approach can be successfully used in studies of systems of closely spaced arrays

Essential thrombocythaemia in a child of three years

AbstractEssential thrombocythaemia is a rare pathology in adults and extremely rare in children, making it a diagnostic challenge for paediatricians. The challenge is greater when patients are asymptomatic, despite an incidental discovery of thrombocytosis.We report the case of extreme thrombocytosis found in an asymptomatic child of 3 years with no personal history or familial history. Study protocol started by ruling out laboratory errors, infectious disease, haemolytic anaemia, iron deficiency anaemia and autoimmune diseases. Bone marrow sample confirmed elevated megakaryocyte production, with other cell lines within normal ranges. Genetic analysis (including JAK2 mutation) was also negative, leading to a differential diagnosis of essential thrombocythaemia. Hydroxyurea (10mg/kg) and aspirin (5mg/kg) were prescribed. A moderate reduction in platelet count was achieved after 4 weeks of treatment

Numerical simulations of the cosmic star formation history

The cosmic star formation history in Cold Dark Matter dominated cosmological scenarios is studied by means of hydrodynamical numerical simulations. In particular, we explore a low density model with a Lambda-term and two high density models with different power spectra, all of them being spatially flat. Our simulations employ a fully nonlinear N-body and Eulerian hydrodynamics algorithm with a model for star formation and supernovae feedback that depends on two phenomenological parameters determined in agreement with previous papers. We find a nearly constant star formation rate beyond z=1, and we discuss which facts may determine the decrease in the SFR from z=1 to the present epoch. The Lambda-term cosmology with realistic parameters for star formation and feedback best reproduces the observed star formation history.Comment: 10 pages, 5 figures. Accepted for publication in A&

Local and global gravity

Our long experience with Newtonian potentials has inured us to the view that gravity only produces local effects. In this paper we challenge this quite deeply ingrained notion and explicitly identify some intrinsically global gravitational effects. In particular we show that the global cosmological Hubble flow can actually modify the motions of stars and gas within individual galaxies, and even do so in a way which can apparently eliminate the need for galactic dark matter. Also we show that a classical light wave acquires an observable, global, path dependent phase in traversing a gravitational field. Both of these effects serve to underscore the intrinsic difference between non-relativistic and relativistic gravity.Comment: LaTeX, 20 pages plus three figures in two postscript files. To appear in a special issue of Foundations of Physics honoring Professor Lawrence Horwitz on the occasion of his 65th birthday; A. van der Merwe and S. Raby, Editors, Plenum Publishing Company, N.Y., 199

UMBRAL DE DISCRIMINACIÓN DE DOS PUNTOS EN DISTINTAS REGIONES ANATÓMICAS EN MUJERES

Este proyecto se realiza con el objetivo de realizar una prueba de discriminación de dos puntos en distintas regiones anatómicas en un grupo de doce mujeres estudiantes de Medicina. La anterior prueba logra medir de una forma eficaz la sensibilidad somática del paciente. Se determina que la precisión de la ubicación donde se realiza el estímulo depende de los campos sensoriales de los receptores. En conclusión, se afirma que existe una diferencia en el umbral de discriminación entre dos puntos en las diferentes regiones anatómicas.Este proyecto se realiza con el objetivo de realizar una prueba de discriminación de dos puntos en distintas regiones anatómicas en un grupo de doce mujeres estudiantes de Medicina. La anterior prueba logra medir de una forma eficaz la sensibilidad somática del paciente. Se determina que la precisión de la ubicación donde se realiza el estímulo depende de los campos sensoriales de los receptores. En conclusión, se afirma que existe una diferencia en el umbral de discriminación entre dos puntos en las diferentes regiones anatómicas

Combined therapy in diabetic macular edema

Purpose: To determine the effectiveness of three different combinations for the ‘‘loading phase’’ in the treatment of diabetic macular edema (DME), using bevacizumab (BVZ), triamcinolone (TCL) and subthreshold macular photocoagulation (SMPC). Methods: Experimental, longitudinal, prospective, comparative and blind. Patients were randomly assigned to three treatment branches: Group 1: BVZ + SMPC (12 eyes), Group 2: SMPC + BVZ + TCL (7 eyes), Group 3: BVZ + TCL (11 eyes). Treatment with BVZ and TCL was given every 4 weeks for 3 months, SMPC was applied once at the beginning of treatment. Initial and final measurements of best corrected visual acuity (BCVA), central macular thickness (CMT) and intraocular pressure (IOP) were tested. Results: The improvement in BCVA and the reduction in CMT was statistically superior in group of BVZ + SMPCwhen compared to the other groups. There were no differences in IOP. Conclusions: Combined therapies in the ‘‘loading phase’’are a good option when treating DME. Although the group with BVZ + SMPC obtained the best results, further studies with longer followup and a higher number of participants to establish this combined therapy as the first treatment option are required

Estética en odontopediatría: restauración indirecta con resina compuesta en dentición primaria

El objetivo del presente trabajo fue realizar una restauración indirecta de resina de fotocurado de clase II en un segundo molar primario y presentar los pasos operatorios realizados como una alternativa estética terapéutica. Paciente de 8 años de edad de sexo femenino asistió para su rehabilitación integral a la Especialidad de Odontopediatría de la Facultad de Odontología de la UNNE. Al examen clínico la pieza dentaria 6.5 presentó una caries inactiva de Clase II compleja, en la cual dentro del plan de tratamiento rehabilitador se decidió realizar una restauración indirecta de resina de fotocurado. Las restauraciones indirectas para molares con resina de fotocurado confeccionado extraoralmente, son una posible alternativa estética, permitiendo optimizar las condiciones clínicas de trabajo y mejorar las propiedades finales del material restaurador