Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 4 de 4
Filtrar
Mais filtros











Intervalo de ano de publicação
1.
J Chem Phys ; 155(4): 044704, 2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34340392

RESUMO

The world desperately needs new technologies and solutions for gas capture and separation. To make this possible, molecular modeling is applied here to investigate the structural, thermodynamic, and dynamical properties of a model for the poly(urethane urea) (PUU) oligomer model to selectively capture CO2 in the presence of CH4. In this work, we applied a well-known approach to derive atomic partial charges for atoms in a polymer chain based on self-consistent sampling using quantum chemistry and stochastic dynamics. The interactions of the gases with the PUU model were studied in a pure gas based system as well as in a gas mixture. A detailed structure characterization revealed high interaction of CO2 molecules with the hard segments of the PUU. Therefore, the structural and energy properties explain the reasons for the greater CO2 sorption than CH4. We find that the CO2 sorption is higher than the CH4 with a selectivity of 7.5 at 298 K for the gas mixture. We characterized the Gibbs dividing surface for each system, and the CO2 is confined for a long time at the gas-oligomer model interface. The simulated oligomer model showed performance above the 2008 Robeson's upper bound and may be a potential material for CO2/CH4 separation. Further computational and experimental studies are needed to evaluate the material.

2.
J Chem Phys ; 146(10): 104502, 2017 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-28298100

RESUMO

Despite the innumerous papers regarding the study of the ionic liquids as a potential candidate for CO2 capture, many details concerning the structure and dynamics of CO2 in the system are still to be revealed, i.e., the correlation between the local environment structure and the dynamic properties of the substance. This present work relied on the performance of molecular dynamics both for the neat [C2mim][Tf2N] and [C2mim][Tf2N]/CO2 mixtures in an attempt to elucidate the local environment of CO2 and their effects on the dynamic properties of [C2mim][Tf2N]. A slight change in the orientation of the cation and anion could be observed, which was correlated to the cation and anion moving away from each other in order to receive the carbon dioxide. The gas molecules pushed both the cation and the anion away to create sufficient void to its accommodation. The diffusion coefficient of [C2mim]+ is higher than [Tf2N]- regardless the increase of the CO2 concentration. The addition of CO2 in the ionic liquid has shown an increase of 4-5 times for the diffusivity of ions, which was related to the decrease of cation-anion interaction strength. The transport properties' results showed that the addition of CO2 in the ionic liquid generates the fluidization of the system, decreasing the viscosity as a consequence of the local environment structure changing. Likewise, the effect of the type of anion and cation on the system properties was studied considering [Ac]- and [BMpyr]+ ions, showing large effects by the change of anion to [Ac]- which rise from the strong [C2mim]+-[Ac]- interaction, which conditions the solvation of ions by CO2 molecules.

3.
Enferm. univ ; 7(3): 7-15, Jul.-sep. 2010. graf
Artigo em Espanhol | LILACS, BDENF - Enfermagem | ID: biblio-1028548

RESUMO

Los niños en estado crítico representan el 16.9 a 26%de hospitalización en el d. f.; y se encuentran en riesgo de sufrir trastornos en la piel y de desarrollar úlceras por presión (upp). En México sólo existe un estudio de investigación sobre upp en pediatría, hecho que no descarta la presencia de estas lesiones en la población nacional. Éste trabajo es el resultado de una investigación realizada en un hospital de tercer nivel del sector salud del Distrito Federal, objetivos: analizar la asociación que existe entre los cuidados de enfermería que se proporcionan a la piel del niño críticamente enfermo y el desarrollo de upp, así como identificar la relación existente entre los factores de riesgo y la aparición de las mismas. Metodología: Se realizó un estudio correlacional y longitudinal, en niños de 6 a 12 años internados en áreas críticas de un hospital de tercer nivel del sector salud del d. f., el instrumento utilizado fue la Escala de Braden y la Cédula de valoración y seguimiento de upp. En cuanto a las enfermeras encargadas del cuidado de los niños, se aplicó la Guía de observación para identificar los cuidados de enfermería brindados a la piel. Resultados: Se observó a un total de 77 enfermeras; distribuidas en tres turnos, los cuidados que brindaron a la piel del niño, alcanzaron un nivel de cuidado adecuado del 19.5 %. En cuanto a la población infantil se observó a 35 niños (71.4% del sexo masculino). El nivel de riesgo de upp en los niños fue alto (68.6%, Escala de Braden); 82.9% presentó alguna upp, 58.6% Con lesiones estadio I, y los sitios de aparición en la región occipital, talones, omóplatos, glúteos y sacro. La prueba de Spearman reveló una relación lineal estadísticamente significativa, débil e inversamente proporcional entre el nivel del cuidado a la piel del niño y el desarrollo upp (rs= -.310, p=.006), lo mismo se encontró al relacionar el índice de riesgo de upp y el desarrollo de estas lesiones (rs= .384, p=.001). Discusión: La relación existente entre los factores de riesgo y el desarrollo de las upp, así como la asociación que hay entre el nivel de calidad de cuidado y la presencia de estas lesiones en niños en estado crítico, favorece la incidencia de upp en un hospital de tercer nivel del d.f., la cual resulta alarmante al compararla con los resultados obtenidos en otras investigaciones. Conclusiones: Es necesario considerar que para asegurar la prevención de las upp se requiere de la participación de diferentes áreas y niveles jerárquicos, por lo que no es responsabilidad única de la enfermera la calidad del cuidado que proporcione, ya que para eso se requiere disponibilidad y accesibilidad de los recursos humanos y materiales, continuidad en el cuidado, competencia técnica y satisfacción del usuario.


Comprising 16.9%-26% of Mexico City Federal District's total hospi-talizations, children in critical status are at risk of developing pressure ulcers (pu). Despite the few related studies conducted in Mexico, a prevalence of this kind of lesions among Mexican children does exist. Conducted in a Federal District health sector third level hospital, the principal objective of this study was to analyze the association and risk factors between Nursing care and the development of pres-sure ulcers in a sample of critically ill Mexican children. Methodology: basic-cor-relational study on 6-12 year old children in critical care units of a Federal District health sector third level hospital; the Braden Scale, the Mexican pu Assessment and Follow-Up Card, and a Nursing Care Observation Guide were used. Results: 77 nurses distributed in 3 shifts, and 35 children (25 male) were observed. The pu risk among children was found to be 68.6% (Braden Scale); 29 children (≈82.9%) developed at least one pressure ulcer; 58.6% of them were grade 1 (or stage 1), and they were mainly located at the occipital, heels, shoulder-blades, and sacrum regions. The Spearman tests revealed an inverse statistically significant linear rela-tion between the skin care and the development of pu (rs1 = -.310, p = .006), while a positive relation between pu risk and its prevalence (rs2 = .384, p = .001). Discus-sion: Considering these results, the pu risk factors - Nursing care - pu development prevalence relation turned out to be critical. Conclusions: In order to prevent pus, it is necessary to provide care with quality, but also to have adequate hospital and staff resources and supports.


Assuntos
Humanos , Criança , Criança , Úlcera por Pressão , Cuidado da Criança
4.
Enferm. univ ; 5(1): 45-48, Ene.-mar 2008. ilus
Artigo em Espanhol | LILACS, BDENF - Enfermagem | ID: biblio-1028474

RESUMO

Este trabajo pretende resaltar el fenómeno de intersubjetividad en la relación Enfermera persona; rescatando la concepción humanista de la práctica profesional del cuidado. Debido a las múltiples visiones teóricas que existen entorno a la intersubjetividad el análisis de este trabajo se centra en la propuesta de Alfred Schütz, sobre la teoría de comprensión intersubjetiva, que se sitúa en el ámbito de las relaciones sociales, y que plantea la interacción sujeto ­ sujeto, donde ambos aprenden, comparten y reconocen su humanidad, que en el terreno de la Enfermería permite tener una visión del ser humano como persona única, singular e indivisible. El fenómeno intersubjetivo, permite el encuentro con el otro u otros, de una forma más integral y humana, por lo que es un elemento indispensable en la relación Enfermera ­ persona, tal cual lo sustentan las teorías disciplinarias de H. Peplau, J. Paterson y L. Zderad, J. Travelbee, J. Watson y R. Parse, donde cada una plantea su propia perspectiva de intersubjetividad. Para ello el ensayo presenta de manera general algunos referentes del fenómeno de intersubjetividad desde la perspectiva de Alfred Schütz, para con ello analizar las teorías de Enfermería de H. Peplau, J. Paterson y L. Zderad, J. Travelbee, J. Watson y R. Parse, y reconocer aspectos de convergencia.


This work tries to emphasize the phenomenon of intersubjectivity in the relation person nurse; rescuing the conception humanist of the professional practice of the care. Due to the multiple theoretical visions that exist surroundings to the intersubjectivity the analysis of this work is centered in the proposal of Alfred Schütz, on the theory of intersubjective understanding, that it locates itself in the scope of the social relations, and which it raises the subject interaction - subject, where both learn, they share and they recognize his humanity, that in the land of the infirmary allow to have a vision of the human being like unique person, singular and indivisible. The intersubjective phenomenon, allows the encounter with the other either others, of one more an integral and human form, reason why it is an indispensable element in the relation nurse - person, so as they sustain the disciplinary theories to it of H. Peplau, J. Paterson and L. Zderad, J. Travelbee, J. Watson and Even R., where each one raises its own perspective of intersubjectivity. For it the test presents/displays of general way some referring ones of the intersubjectivity phenomenon from the perspective of Alfred Schütz, towards it to analyze theories of infirmary of H. Peplau, J. Paterson and L. Zderad, J. Travelbee, J. Watson and Even R. and to recognize aspects of convergence.


Assuntos
Humanos , Cuidados de Enfermagem , Enfermeiras e Enfermeiros , Relações Enfermeiro-Paciente
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA