Modelling studies on neurodegenerative disease causing triplet repeat sequences d(CGG/GCC) and d(CAG/CTG): Duplexes vs Quadruplexes

Model building and molecular mechanics studies have been carried out to examine the potential structures for d(GGC/GCC)5 and d(CAG/CTG)5 that might relate to their biological function and association with triplet repeat expansion diseases. Model building studies suggested that hairpin and quadruplex structures could be formed with these repeat sequences. Molecular mechanics studies have demonstrated that the hairpin and hairpin dimmer structures of triplet repeat sequences formed by looping out of the two strands are as favourable as the corresponding B-DNA type hetero duplex structures. Further, at high salt condition, Greek key type quadruplex structures are energetically comparable with hairpin dimer and B-DNA type duplex structures. All tetrads in the quadruplex structures are well stacked and provide favourable stacking energy values. Interestingly, in the energy minimized hairpin dimer and Greek key type quadruplex structures, all the bases even in the non-G tetrads are cyclically hydrogen bonded, even though the A, C and T-tetrads were not hydrogen bonded in the starting structures.

Experimental Study on the Ignition Process of Single Coal Particles at Microgravity

In this paper, the first Chinese microgravity (μ-g) experimental study on coal combustion was introduced. An experimental system used to study the ignition process of single coal particles was built up, complying with the requirements of the 3.5 s drop tower in the National Microgravity Laboratory of China (NMLC). High volatile bituminous and lignite coal particles with diameter of 1.5 and 2.0 mm were tested. The ignition and combustion process was recorded by a color CCD and the particle surface temperature before and at the ignition was determined by the RGB colorimetric method. Comparative experiments were conducted at normal gravity (1-g). The experiments revealed that at different gravity levels, the ignition of all tested coal particles commenced in homogeneous phase, while the shape, structure, brightness and development of the flames, as well as the volatile matter release during the ignition process are different. At μ-g, the part of volatile was released as a jet, while such a phenomenon was barely observed at 1-g. Also, after ignition, flames were more spherical, thicker, laminated and dimmer at μ-g. It was confirmed that ignition temperature decreased as the particle size or volatile content increased. However, contradicted to existing experimental results, provided other experimental conditions except gravity level were the same, ignition temperature of coal particles was about 50–80 K lower at μ-g than that at 1-g.

Estudo do impacto do descarte dos comprimidos de captopril no meio ambiente

O Captopril é um dos medicamentos anti-hipertensivos mais consumidos no Brasil. Constitui-se em um pó cristalino, branco ou levemente amarelado, com leve odor característico de sulfeto, facilmente solúvel em água, etanol, clorofórmio e metanol. Em soluções aquosas, o captopril sofre reação de oxidação, formando em quantidade crescente como produto de degradação o dímero dissulfeto de captopril. Além disso, no período de 24 horas, mais de 95% da dose absorvida é eliminada pela urina, sendo 40 a 50% na forma inalterada, e o restante na forma do dímero dissulfeto de captopril e de outros metabólitos, os quais são encaminhados para o esgoto, podendo assim atingir os corpos dágua. O presente trabalho foi planejado de maneira a estudar o impacto e o comportamento do medicamento e do seu produto de degradação em águas ambientais. Para isso, foi feita a validação do método analítico escolhido, cromatografia líquida de alta eficiência, que foi a ferramenta adequada para garantir a confiabilidade dos dados analíticos do método. Foi monitorada também a estabilidade do fármaco na forma de comprimidos e em solução aquosa, ao longo de 144 dias. Os resultados mostraram que quando os comprimidos de captopril são armazenados em sua embalagem original, nesse caso blister, a uma temperatura controlada igual a 40o C e umidade controlada igual a 75 %, eles permaneceram estáveis. A concentração de captopril apresentou uma média igual a 97,4 %. Por outro lado, quando diluído e armazenado nas mesmas condições de temperatura e umidade citadas anteriormente para a obtenção de uma solução aquosa na concentração igual a 1 mg/mL, a substância captopril chegou a variar de 95,7% a 68,5%. Já o seu produto de degradação, dissulfeto de captopril, atingiu um aumento na concentração de 1,7 para 31,1%, ambos em 144 dias

Study on the biodegradation process of poly (3-hydroxybutyrate)

Poly (3-hydroxybutyrate) (PHB) films were biodegraded by DS9701. The degradation process was monitored by using SEM. It was shown that the PHB degradation occurred firstly in the amorphous part of PHB and then in the crystalline part, especially from the center of PHB spherulites. PHB deplymerase produced by DS9701 mainly attacked the second ester bond of PHB and the degraded product was dimmer, determined by using mass spectrometer.

STUDIES ON STATES OF CYTOCHROME-C MOLECULES IN AQUOUS SOLUTIONS USING SYNCHRONOUS FLUORESCENCE SPECTROSCOPY

The states of cytochrome C molecules in aquous solution were studied with synchronous fluorescence spectroscopy, It was found that the synchronous fluorescent spectra of cytochrome C were contributed by tyrosine and tryptophan residues separately at Delta lambda = 20 nm and Delta lambda = 80 nm, The peak position in synchronous fluorescent spectra of tyrosine residues in cytochrome C molecule does not change with its concentration, but that of tryptophan residue changes with its concentration, Only one peak at 340.0 nm was observed in the dilute solution of cytochrome C, With increasing the concentration of cytochrome C, a new peak at 304. 0 nm appeared. The peak at 340.0 nm disappeared and only one peak at 304.0 nm was observed at a higher concentration of cytochrome C, It may originate from the change of aggregation states of cytochrome C molecules and it was considered that the peak at 340.0 nm was attributed to the monomer and peak at 304.0 nm was due to the dimmer or oligomers. When urea was added into cytochrome C solution in which both monomer and dimmer or oligomers exist, cytochrome C molecules do not denature in the range of the specific concentrations of urea. The concentration of monomer of cytochrome C molecules increased and that of aggregation slates decreased by adding urea, Therefore, the synchronous fluorescence spectroscopy can be used to identify monomer and aggregation states of cytochrome C molecules.

Study of the production of polyesters for polyurethanes at pilot plant scale

Dissertação para obtenção do grau de Mestre em Engenharia Química

Tratamiento de la ulcera venosa con escleroespuma versus manejo conservador

La úlcera venosa es una revelación clínica severa de la insuficiencia venosa crónica. Es la causa del 54-76% de las úlceras venosas de miembros inferiores. La ciencia médica ha generado diversos procedimientos en el manejo de esta patología, es así como a partir de conocimientos en fisiopatología de la ulceración venosa, se han aplicado procedimientos como opción de tratamiento. Objetivos: Valorar si el uso de rutina de la oclusión endoluminal con espuma guiada por ecografía del sistema venoso superficial insuficiente, en adicción al manejo convencional de la ulcera venosa (vendaje no compresivo, gasa vaselinada y curaciones) podría mejorar la tasa de curación a las 24 semanas de tratamiento. Diseño: Estudio clínico aleatorizado prospectivo de pacientes de la consulta externa de cirugía vascular del Hospital Occidente de Kennedy-Bogotá, durante el 01 de junio del 2011 hasta el 30 junio del 2012. Métodos: Un total de 44 pacientes con ulcera activa que cumplieron criterios de selección ingresaron al estudio, correspondientes a 48 extremidades con clasificación CEAP (C6), los pacientes fueron a aleatorizados a manejo convencional (control) o con manejo adicional de oclusión endoluminal con espuma eco-guiada. El objetivo principal fue el cierre de la ulcera a las 24 semanas. Resultados: La Curación de la ulcera a las 24 semanas de la aleatorización fue de 20 (83.3%) extremidades del grupo de oclusión endoluminal con espuma eco-guiada Vs 3(12.5%) para el grupo de control P: 0.0005 Discusión: Las tasas de curación de la ulcera luego de la oclusión endoluminal con espuma eco-guiada es muy superior al manejo convencional con curaciones y vendaje no compresivo, las tasa de curación son tan altas como las reportadas con sistemas de alta compresión y cirugía a las 24 semanas. La oclusión endoluminal eco-guiada es segura, mínimamente invasiva y clínicamente efectiva.

Factores de riesgo para el desarrollo de complicaciones: infecciones en varicosafenectomia

La enfermedad venosa periférica de miembros inferiores se considera una de las afecciones más prevalentes, con morbilidad considerable, deterioro de la calidad de vida, e importante demanda de recursos de salud, que en la mayoría de casos requiere manejo quirúrgico como parte del tratamiento. Este estudio busca analizar si la técnica quirúrgica es un factor de riesgo, que incrementa la aparición de infección de sitio quirúrgico en 257 pacientes a quienes se les realizó varicosafenectomia. Metodología: Se realizó un estudio de cohorte retrospectiva; se recolectaron los datos a partir de los registros clínicos y quirúrgicos de pacientes que cumplieron con los criterios de inclusión, registrando factores de riesgo, descripción quirúrgica, complicaciones, y evolución post operatoria hasta 8 semanas. El análisis estadístico se realizó mediante el cálculo de riesgo relativo y regresión logística binomial. Resultados: Se demostró asociación entre la presencia de infección de sitio quirúrgico y tipo de cirugía con un RR = 3,05 (P= 0,01), clasificación CEAP con 29% menos riesgo en varicosafenectomia total (P= 0,008). Conclusiones: Existen variables clínicas y quirúrgicas que influyen en la probabilidad de desarrollar infección del sitio quirúrgico.

Hallazgos radiológicos de la enfermedad pulmonar en pacientes Colombianos con esclerodermia

La esclerosis sistémica (ES) es una enfermedad autoinmune multisistémica que afecta principalmente la piel, los pulmones, el tracto gastrointestinal, el corazón y los riñones. La enfermedad pulmonar, presente en casi el 100% de los casos, es el factor con mayor influencia en la mortalidad. El propósito de este estudio es realizar un análisis detallado de la enfermedad pulmonar por tomografía computarizada de alta resolución(TCAR) en pacientes Colombianos con ES, para lo cual se realizó un estudio de prevalencia analítica en 44 pacientes con ES valorados en el Hospital Universitario Mayor Méderi en los últimos 7 años. Los resultados mostraron características demográficas y clínicas similares a las previamente descritas. La prevalencia de enfermedad pulmonar intersticial fue alta, y los hallazgos de fibrosis pulmonar como vidrio esmerilado y panal de abejas se asociaron con la presencia del autoanticuerpo antiSCL70. La medida del diámetro esofágico por TCAR fue mayor en los pacientes con disfagia, antiSCL 70 y linfopenia, los cuales son marcadores de mal pronóstico.

On the seasonal onset of polar mesospheric clouds and the breakdown of the stratospheric polar vortex in the Southern Hemisphere

Southern Hemisphere (SH) polar mesospheric clouds (PMCs), also known as noctilucent clouds, have been observed to be more variable and, in general, dimmer than their Northern Hemisphere (NH) counterparts. The precise cause of these hemispheric differences is not well understood. This paper focuses on one aspect of the hemispheric differences: the timing of the PMC season onset. Observations from the Aeronomy of Ice in the Mesosphere satellite indicate that in recent years the date on which the PMC season begins varies much more in the SH than in the NH. Using the Canadian Middle Atmosphere Model, we show that the generation of sufficiently low temperatures necessary for cloud formation in the SH summer polar mesosphere is perturbed by year‐to‐year variations in the timing of the late‐spring breakdown of the SH stratospheric polar vortex. These stratospheric variations, which persist until the end of December, influence the propagation of gravity waves up to the mesosphere. This adds a stratospheric control to the temperatures in the polar mesopause region during early summer, which causes the onset of PMCs to vary from one year to another. This effect is much stronger in the SH than in the NH because the breakdown of the polar vortex occurs much later in the SH, closer in time to the PMC season.

Ground-based and satellite observations of high-latitude auroral activity in the dusk sector of the auroral oval

On 7 December 2000, during 13:30-15:30 UT the MIRACLE all-sky camera at Ny Alesund observed auroras at high-latitudes (MLAT similar to 76) simultaneously when the Cluster spacecraft were skimming the magnetopause in the same MLT sector (at similar to 16:00-18:00 MLT). The location of the auroras (near the ionospheric convection reversal boundary) and the clear correlation between their dynamics and IMF variations suggests their close relationship with R1 currents. Consequently, we can assume that the Cluster spacecraft were making observations in the magnetospheric region associated with the auroras, although exact magnetic conjugacy between the ground-based and satellite observations did not exist. The solar wind variations appeared to control both the behaviour of the auroras and the magnetopause dynamics. Auroral structures were observed at Ny Alesund especially during periods of negative IMF B-Z. In addition, the Cluster spacecraft experienced periodic (T similar to 4 - 6 min) encounters between magnetospheric and magnetosheath plasmas. These undulations of the boundary can be interpreted as a consequence of tailward propagating magnetopause surface waves. Simultaneous dusk sector ground-based observations show weak, but discernible magnetic pulsations (Pc 5) and occasionally periodic variations (T - 2 - 3 min) in the high-latitude auroras. In the dusk sector, Pc 5 activity was stronger and had characteristics that were consistent with a field line resonance type of activity. When IMF BZ stayed positive for a longer period, the auroras were dimmer and the spacecraft stayed at the outer edge of the magnetopause where they observed electromagnetic pulsations with T similar to 1 min. We find these observations interesting especially from the viewpoint of previously presented studies relating poleward-moving high-latitude auroras with pulsation activity and MHD waves propagating at the magnetospheric boundary layers.

Identification of oligomers in polyethyleneterephthalate bottles for mineral water and fruit juice - Development and validation of a high-performance liquid chromatographic method for the determination of first series cyclic trimer

Cyclic oligomers were identified in PET bottles used for mineral water and fruit juice using MS and H-1 and C-13 NMR: a first series cyclic trimer, a first series cyclic tetramer, a first series cyclic dimmer and a second series cyclic trimer. An analytical method to determine first series cyclic trimer in these bottles was developed and validated, using HPLC. The first series cyclic trimer levels were 316-462 mg/100 g of PET bottle. (c) 2005 Elsevier B.V. All rights reserved.

Energetic efficiency programs and power quality

This paper presents the results of the investigations that were done to identify and to quantify the power quality problems resultant from the actions done to improve the efficiency on electric energy consumption. The efficiencies of several electric devices were evaluated, among them: fluorescent bulb, electronic ballast, soft-starter, temperature controller for showers, dimmer and others. This evaluation allowed to establish a cause/effect analysis of the power quality.

Thermolysis of octa (hydridodimethylsiloxyl) octasilsesquioxane in pyridine media and subsequent toluidine blue O adsorption

This work describes the synthesis of octa (hydridodimethylsiloxyl) octasilsesquioxane, (Q(8)M(8)(H)) and its thermolysis in pyridine media. The new compound called CPy was characterized by FTIR, NMR-MAS, XRD, MEV spectroscopies and TGA analyses. These results indicate that silsesquioxanes cages (octanion) are maintained after thermal treatment. A cleavage of vertex siloxy groups yielding a nanocomposite with polymeric nature is proposed. Its structure and morphology allows the adsorption/inclusion of electrochemical mediator, toluidine blue O. The square wave voltammetry analysis of resulting composite (CPyTBO) exhibits two redox couple with a formal potential (E-0') 0.1 V and 0.26 V to I and II redox couples respectively, (Britton-Robinson (BR) buffer pH 3, v = 10 Hz versus SCE) ascribed to a monomer and dimmer of the toluidine blue species. This paper opens the use of spherosiloxane derived materials a's host for small molecules in the electrochemical field. (C) 2004 Elsevier B.V. All rights reserved.