Hydrolytic degradation of poly(ε-caprolactone) with different end groups and poly(ε-caprolactone-co--Y-butyrolactone): characterization and kinetics of hydrocortisone delivery

7 páginas, 8 figuras, 2 tablas.-- El pdf es el borrador del artículo.Asymmetric telechelic alfa-hydroxyl-ω-(carboxylic acid)-poly(ε-caprolactone) (HA-PCL), alfa-hydroxyl-ω-(benzylic ester)-poly(ε-caprolactone) (HBz-PCL), and an asymmetric telechelic copolymer alfa-hydroxyl-ω-(carboxylic acid)-poly(ε-caprolactone-co-Y-butyrolactone) (HA-PCB) were synthesized by ring-opening polymerization of ε-caprolactone (CL). CL and CL/-butyrolactone mixture were used to obtain homopolymers and copolymer respectively at 150°C and 2 hr using ammonium decamolybdate (NH4) [Mo10O34] (Dec) as a catalyst. Water (HA-PCL and HA-PCB) or benzyl alcohol (HBz-PCL) were used as initiators. The three polylactones reached initial molecular weights between 2000 and 3000 Da measured by proton nuclear magnetic resonance (1H-NMR). Compression-molded polylactone caplets were allowed to degrade in 0.5 M aqueous p-toluenesulfonic acid at 37°C and monitored up to 60 days for weight loss behavior. Data showed that the copolymer degraded faster than the PCL homopolymers, and that there was no difference in the weight loss behavior between HA-PCL and HBz-PCL. Caplets of the three polylactones containing 1% (w/w) hydrocortisone were placed in two different buffer systems, pH 5.0 with citrate buffer and pH 7.4 with phosphate buffer at 37°C, and monitored up to 50 days for their release behavior. The release profiles of hydrocortisone presented two stages. The introduction of a second monomer in the polymer chain significantly increased the release rate, the degradation rate for HA-PCB being faster than those for HBz-PCL and HA-PCL. At the pH studied, only slight differences on the liberation profiles were observed. SEM micrographs indicate that hydrolytic degradation occurred mainly by a surface erosion mechanism.The financial support by Consejo Nacional de Ciencia y Tecnología and Universidad de Guanajuato is acknowledged. L.M.O.C. thanks Consejo Nacional de Ciencia y Technología (CONACYT) for a Ph.D. scholarship.Peer reviewe

Experimentação de carga durante os cuidados, principais características a ter em consideração para a sua intervenção: dimensões negativas, efeitos e instrumentos de medição

Durante el transcurso de los cuidados y especialmente en los denominados de larga duración, es muy proclive el generarse determinadas situaciones conflictivas a consecuencia de diversos factores tales como, un excesivo volumen de trabajo, elevada responsabilidad, problemas relacionales entre cuidador y persona objeto de cuidados etc. Conllevando a la experimentación de cansancio, estrés y agotamiento principalmente. Todas esas situaciones negativas es lo que muchos autores definen con el concepto de carga o sobrecarga de los cuidados, constituyendo un habitual ámbito de estudio en las investigaciones que versan sobre esta temática. El propósito de este artículo, consiste en llevar a cabo una aproximación conceptual del término de carga, experimentada durante el transcurso de las actividades de cuidados, analizando las dimensiones más relevantes de la misma en primer término, haciendo una distinción entre los conceptos de carga objetiva y subjetiva en segundo término, analizar las principales consecuencias que generan a los cuidadores tales como, percibimiento de sentimientos negativos, problemas de salud física, psíquica, trastornos cardiovasculares e inmunológicos en tercer término, las principales variables asociadas al concepto de carga, y finalmente los principales instrumentos de evaluación de la carga del cuidador.During the provision of cares and, particularly in long-term care, conflictive situations are generated frequently as a consequence of factors such as, excessive workload, high responsibility, relational problems between caregiver and the person subject of care etc., mainly leading to the experimentation of fatigue, stress and exhaustion. All these negative situations are what many authors call burden or overload of care, constituting a common field of study in the research dealing with this subject. The purpose of this article is to frame a conceptual approach to the concept of load experienced during the care, analyzing the most relevant factors contributing to such load, first making a distinction between the concepts of objective and subjective burden, secondly by analyzing the principal consequences for caregivers, such as perceived negative feelings, physical and mental health problems, cardiovascular disorders and immunological problems. Principal variables associated with the concept of burden, and finally the main instruments of evaluation of the caregiver burden are shown.Durante o curso dos cuidados e, especialmente, nos chamados longo prazo, é muito provável que os gerados certas situações de conflito, como resultado de vários fatores, como carga de trabalho excessiva, alta responsabilidade, problemas de relacionamento entre cuidador e pessoa a ser cuidada etc. . Levando à experimentação de fadiga, estresse e exaustão principalmente. Todas estas situações negativas é o que muitos autores definem o conceito de carga ou sobrecarga de atendimento, proporcionando um campo comum de estudo em investigações que lidam com este assunto. O objetivo deste artigo é realizar uma abordagem conceitual da carga prazo experimentaram durante o curso das atividades de atendimento, analisando as dimensões mais relevantes da primeira, fazendo uma distinção entre os conceitos de sobrecarga objetiva e subjetivos em segundo lugar, analisar as principais conseqüências geradas cuidadores, como percibimiento sentimentos negativos, problemas físicos de saúde, transtornos mentais, cardiovasculares e imunológicas terceiro, as principais variáveis associadas com o conceito de carga e, finalmente, principais instrumentos de avaliação do ônus do cuidador

Simulations of starting gas jets at low mach numbers

The starting jet produced by the impulsively started discharge of a submerged gas stream of constant velocity through a circular orifice in a plane wall is investigated by integrating numerically the axisymmetric Navier-Stokes equations for moderately large values of the jet Reynolds number. The analysis is restricted to low-Mach-number jets, for which the jet-to-ambient temperature ratio gamma=T/sub j//T/sub o/ emerges as the most relevant parameter. It is seen that the leading vortex approaches a quasisteady structure propagating at an almost constant velocity, which is larger for smaller values of gamma. The action of the baroclinic torque in regions of nonuniform temperature leads to significant vorticity production, with a constant overall rate equal to that of an inviscid starting je

Numerical analyses of deflagration initiation by a hot jet

Numerical simulations of axisymmetric reactive jets with one-step Arrhenius kinetics are used to investigate the problem of deflagration initiation in a premixed fuel–air mixture by the sudden discharge of a hot jet of its adiabatic reaction products. For the moderately large values of the jet Reynolds number considered in the computations, chemical reaction is seen to occur initially in the thin mixing layer that separates the hot products from the cold reactants. This mixing layer is wrapped around by the starting vortex, thereby enhancingmixing at the jet head, which is followed by an annular mixing layer that trails behind, connecting the leading vortex with the orifice rim. A successful deflagration is seen to develop for values of the orifice radius larger than a critical value aϲ in the order of the flame thickness of the planar deflagration δL. Introduction of appropriate scales provides the dimensionless formulation of the problem, with flame initiation characterised in terms of a critical Damk¨ohler number ∆ϲ = (aϲ/δL)², whose parametric dependence is investigated. The numerical computations reveal that, while the jet Reynolds number exerts a limited influence on the criticality conditions, the effect of the reactant diffusivity on ignition is much more pronounced, with the value of ∆ϲ increasing significantly with increasing Lewis numbers Le. The reactant diffusivity affects also the way ignition takes place, so that for reactants with Le ≳ 1 the flame develops as a result of ignition in the annular mixing layer surrounding the developing jet stem, whereas for highly diffusive reactants with Lewis numbers sufficiently smaller than unity combustion is initiated in the mixed core formed around the starting vortex. The analysis provides increased understanding of deflagration initiation processes, including the effects of differential diffusion, and points to the need for further investigations incorporating detailed chemistry models for specific fuel–air mixtures.This work was supported by the SpanishMCINN through project numbers ENE2008-06515-C01 and CSD2010-00010 and by the Comunidad de Madrid through project number S2009/ENE-1597

Levantamiento Topográfico de calle "La Compostera" del Municipio de Ciudad Sandino, Departamento de Managua con una longitud 713 ml

En las obras de construcción civiles inicialmente se necesita una de sus ramas para los diversos estudios de ingeniería, siendo esta la Topografía ya que por medio de la aplicación de esta ciencia se obtiene una descripción detallada del terreno mediante el análisis planimétrico y altimétrico proporcionando la información para el diseño de la obra a construirse, y generando con esto proyecciones de rasante para una terraza estableciendo niveles deseados para dar inicio a la obra civil. Los levantamientos topográficos se realizan con el fin de determinar el conjunto de desigualdades que existen en la superficie que conforman el relieve, mostrando las dimensiones que el terreno presenta en la determinada área que se propone para el proyecto topográfico que se pretende realizar y su posición sobre la superficie de la tierra, de elementos naturales o instalaciones construidas por el hombre. En este tipo de levantamientos se toman los datos planimétricos y altimétricos para la representación gráfica y elaboración de mapas del área de estudi

Critical radius for hot-jet ignition of hydrogen-air mixtures

This study addresses deflagration initiation of lean and stoichiometric hydrogen–air mixtures by the sudden discharge of a hot jet of their adiabatic combustion products. The objective is to compute the minimum jet radius required for ignition, a relevant quantity of interest for safety and technological applications. For sufficiently small discharge velocities, the numerical solution of the problem requires integration of the axisymmetric Navier–Stokes equations for chemically reacting ideal-gas mixtures, supplemented by standard descriptions of the molecular transport terms and a suitably reduced chemical-kinetic mechanism for the chemistry description. The computations provide the variation of the critical radius for hot-jet ignition with both the jet velocity and the equivalence ratio of the mixture, giving values that vary between a few tens microns to a few hundred microns in the range of conditions explored. For a given equivalence ratio, the critical radius is found to increase with increasing injection velocities, although the increase is only moderately large. On the other hand, for a given injection velocity, the smallest critical radius is found at stoichiometric conditions.This work was partially supported by Project S-505/ENE/0229 of the Spanish Comunidad de Madrid, and by projects CSD2010-00011 (CONSOLIDER-INGENIO) and MTM2010-18079 of the Spanish Ministerio de Economía y Competitivida

Effects of differential diffusion on nonpremixed-flame temperature

This numerical and analytical study investigates effects of differential diffusion on nonpremixed-flame temperatures. To focus more directly on transport effects the work considers a single irreversible reaction with an infinitely fast rate, with Schab-Zel'dovich coupling functions introduced to write the conservation equations of energy and reactants in a chemistry-free form accounting for non-unity values of the fuel Lewis number L-F. Different flow configurations of increasing complexity are analyzed, beginning with canonical flamelet models that are reducible to ordinary differential equations, for which the variation of the flame temperature with fuel-feed dilution and L-F is quantified, revealing larger departures from adiabatic values in dilute configurations with oxidizer-to-fuel stoichiometric ratios S of order unity. Marble&#39;s problem of an unsteady flame wrapped by a line vortex is considered next, with specific attention given to large-Peclet-number solutions. Unexpected effects of differential diffusion are encountered for S < 1 near the vortex core, including superadiabatic/subadibatic flame temperatures occurring for values of L-F larger/smaller than unity as well as temperature profiles peaking on the oxidizer side of the flame. Direct numerical simulations of diffusion flames in a temporal turbulent mixing layer are used to further investigate these unexpected differential- diffusion effects. The results, confirming and extending previous findings, underscore the nontrivial role of differential diffusion in nonpremixed-combustion systems

Gamifying massive online courses: effects on the social networks and course completion rates

This paper analyzes the e ects of gamification in the social network of a massive online course. An educational social-networking platform gathered information about the contributions of participants and about the social networks that were formed during the course. A gamification layer with three game elements (points, badges, and leaderboard) was then implemented in the online learning platform. Social network analysis (SNA) and principal component analysis (PCA) were used to analyze the di erences between a treatment and a comparison group (N = 591 and N = 427), using a set of 20 variables for each participant which quantified contributions to the learning platform as well as position and influence in the social network. The results of SNA show that gamification influences the structure of the social network of the course. The results also suggest that the variables cluster similarly for each group and that the linear combination of variables called the first component (F1) is a good descriptor of students’ work and position in the network. F1 can be used to build predictive models of course completion. The models show that the probability of passing the course increases more rapidly in the treatment (gamified) group.Spanish Ministry of Economic A airs and Digital Transformation (Grant TIN2014-54874-R) and Government of Comunidad de Madrid (Grant CM/JIN/2019-037).info:eu-repo/semantics/publishedVersio

Bone Metabolism in Patients with Hidradenitis Suppurativa: A Case-control Study

Hidradenitis suppurativa (HS) is a chronic inflammatory disease of the hair follicles. The aim of this case-control study was to assess whether HS is associated with disturbances in trabecular bone score, bone mineral density, bone remodelling markers, and calciotropic hormones. A total of 81 patients and 79 controls of similar age and sex were included. Demographic, anthropometric, laboratory data, trabecular bone score, bone mineral density, serum 25-hydroxyvitamin D (25OHD), serum amino-terminal pro-peptide of type 1 collagen (PINP), and C-terminal telopeptide of type 1 collagen (CTX) concentrations were assessed in both groups. Patients with HS had lower serum 25OHD levels than controls, and approximately 62% of them had vitamin D deficiency. Serum PINP was increased and CTX was decreased in patients with HS. Fully adjusted trabecular bone score values were lower in patients with HS compared with controls. Adjusted lumbar bone mineral density was similar in HS and controls, whilst total hip bone mineral density was lower in patients with HS. There were no statistical differences regarding disease severity in terms of 25OHD, serum turnover markers, bone mineral density, or trabecular bone score values. This study shows that patients with HS have lower trabecular bone score and total hip bone mineral density values than population-based controls. In addition, the prevalence of vitamin D deficiency is high in subjects with HS

Lifted laminar jet diffusion flames

This paper addresses the numerical description of lifted flames in axisymmetric laminar coflow jets. The analysis considers moderately large values of the Reynolds number, when the boundary-layer approximation can be used to describe the slender mixing region that extends between the jet exit and the flame, providing the profiles of velocity and mixture fraction that exist immediately upstream from the flame front region. The description of the nonslender flame front region, which provides the front propagation velocity as an eigenvalue, requires integration of the Navier-Stokes equations with account taken of the reaction and thermal expansion effects. The limiting formulations corresponding to cases of practical interest, including large values of the air-to-fuel stoichiometric ratio, are briefly discussed. Illustrative numerical results are given for flames lifted or propagating at distances small compared with the jet development length, where the mixing layer is nearly planar