Asphaltenes: Aggregates in Terms of A1 and A2 or Island and Archipielago Structures.

In this work several issues related to asphaltenes and asphaltene aggregates such as isolation of real asphaltene molecules and comparison of these with average structures obtained using regular analytics laboratory techniques are presented. Several molecular organic models were used to simulate asphaltene in solution and aggregates formation in the two solvents toluene and THF employed. The results, obtained from simulation calculations using molecular dynamics were compared with experimental chromatography results obtained using the micro gel permeation chromatography (µGPC), inductively coupled plasma (ICP) mass spectra (MS) combined technique (GPC ICP MS for short). In this case reasonable hydrodynamic ratios and size distribution were obtained for asphaltenes and their corresponding subfractions A1 and subfraction A2. Comparison between experimental sample profiles, transmission of electron microscopy (TEM) data, and molecular dynamics allows for estimation of hydrodynamic ratios of around 8 nm. Highly aromatic and island type molecular model A30 and continental type molecular model A40 were employed in the molecular dynamics to built colloids. In this case open-like colloids (A40) and compact-like colloids A30 were obtained. Subjects such as trapped compounds (TC), metallic porphyrins, and colloidal dipole moments were also studied. Studies of the adsorption behavior of asphaltenes on several macroscopic and nanoscopic surfaces are presented and show the tendency of the asphaltene to adsorb in aggregate form.

Identificación en tiempo real de la anatomía biliar mediante fluorescencia utilizando fluoresceína sódica / Real time identification of biliary anatomy by fluorescence using fluorescein sodium

Objetivo: Desarrollar, en un modelo experimental animado, la técnica de colangiografía intraoperatoria utilizando fluoresceína sódica. Determinar la dosis de fluoresceína sódica necesaria para obtener la mejor visualización de la vesícula y del árbol biliar. Método: Estudio de tipo experimental, en el que se incluyeron 6 conejos albinos de raza Nueva Zelanda, distribuidos en 3 grupos equitativamente, según la dosis de fluoresceína sódica (5 mg/kg, 7,5 mg/kg, 15 mg/kg). Cumplido el protocolo anestésico, se administró la dosis de fluoresceína sódica según el grupo correspondiente, vía endovenosa. Se realizó una laparotomía por línea media superior, exteriorizándose el hígado y se realizó una maniobra de eversión, para la fácil identificación del sistema biliar extrahepático. Posteriormente, y con los sistema de iluminación, se registraron los parámetros de fluorescencia con cada dosis. No se realizó eutanasia. Ambiente: Centro veterinario privado "Colmillos y garras" Resultados: En todos los casos se logró registrar fluorescencia, siendo la dosis que permitió una mejor visualización la de 7,5 mg/kg. El tiempo promedio en el cual se empezó a ver fluorescencia en la vesícula biliar fue de 5 minutos; el tiempo promedio en el cual se alcanzó la totalidad del fenómeno fue de 18 minutos y, en todos los casos, la fluorescencia persistió por 30 minutos. Conclusión: La identificación de las vías biliares guiada por fluorescencia, utilizando fluoresceína sódica y con la fuente de luz UV de 5 mm de diámetro diseñada por los autores es factible, siendo la dosis con mejor visualización, la de 7,5 mg /kg de peso(AU)

Objective: To develop an experimental animal model technique using sodium fluorescein intraoperative cholangiography. To Determine the dose of sodium fluorescein necessary for the best display of the gallbladder and biliary tree. Methods: Experimental study. 6 New Zealand white albino rabbits divided into 3 groups depending on the dose of sodium fluorescein (5 mg / kg, 7.5 mg / kg, 15 mg / kg) were used. Prior anesthetic protocol corresponding fluorescein sodium was administered according included Animal group intravenously. Upper midline incision was used, exteriorization of the liver allow easy identification of extrahepatic biliary system and subsequently illuminated with fluorescence. Parameters were recorded for each dose. No euthanasia was performed. Environment: Private Veterinary Centre "Colmillos y Garras". Results: In all cases, we recorded fluorescence. The dose that allowed the best visualization was 7.5 mg / kg. The average time in which fluorescence began to be visible in the gallbladder was 5 minutes, the average time in which the total fluorescence was reached was 18 minutes in all cases fluorescence persisted until 30 minutes. Conclusion: Laparoscopic cholecystectomy guied using sodium fluorescein fluorescence and UV light source of 5 mm diameter is feasible. Better visualization is obtained with the dose 7.5 mg / kg(AU)

Antidiabetic and antiradical activities of plants from Venezuelan Amazon / Atividades antidiabética e anti-radicalar de plantas da Amazônia venezuelana

Os extratos aquoso e etanólico derivados de doze espécies coletadas na Amazônia venezuelana foram testados quanto à atividade antioxidante utilizando um radical DPPH e o efeito inibitório sobre a hidrólise de glicose-6-fosfato nos microssomas intactos e perturbados. Sem exceção, todos os extratos inibiram, em maior ou menor grau, a atividade enzimática microssomal de G-6-Pase, resultando em maior inibição nos microssomas intactos do que nos perturbados. Efeitos marcantes foram observados para os extratos aquoso e etanólico de: Tontelea ovalifolia, Gustavia pulchra, Phthirusa verruculosa, Phthirusa castillana, Psittacanthus acimarius, Tetrapterys styloptyera e Vismia japurensis. Os extratos etanólicos foram seqüestradores do radical DPPH mais eficazes do que os correspondentes extratos aquosos em todos os casos. O extrato etanólico de Endlicheria anomala e o extrato aquoso de Phthirusa verruculosa exibiram as melhores CI50 com 100 e 250.0 ppm, respectivamente. Os valores de Kobs calculados para os extratos alcoólicos foram mais baixos do que os dos extratos aquosos das mesmas espécies, exceto Psittacanthus acimarius. Estes resultados poderiam estar relacionados a diferentes concentrações, ou mais provavelmente a diferentes composições de princípios ativos em ambos extratos.

The aqueous and ethanol extracts derived from twelve plant species collected in the Venezuelan Amazon have been tested for antioxidant activity using a DPPH radical and inhibitory effect on the hydrolysis of glucose-6-phosphate in intact and disrupted microsomes. Without exception, all the extracts inhibited, to a greater or lesser degree, microsomal G-6-Pase enzymatic activity, resulting in greater inhibition on intact microsomes than on disrupted ones. Marked effects were observed for aqueous and ethanol extracts of: Tontelea ovalifolia, Gustavia pulchra, Phthirusa verruculosa, Phthirusa castillana, Psittacanthus acimarius, Tetrapterys styloptyera and Vismia japurensis. Ethanol extracts were more effective DPPH radical scavengers than the corresponding aqueous extracts in all the cases. The ethanol extract of Endlicheria anomala and the aqueous extract of Phthirusa verruculosa, showed the best IC50 with 100 and 250.0 ppm, respectively. The Kobs calculated for the alcoholic extracts were lower than those of the aqueous extracts for the same species, except Psittacanthus acimarius. These results could be related to different concentrations, or more likely different compositions of active principles in both extracts.

Nanosphere lithography: fabrication of large-area Ag nanoparticle arrays by convective self-assembly and their characterization by scanning UV-visible extinction spectroscopy.

This work employs UV-visible extinction spectroscopy as a new spectral mapping technique to characterize self-assembled polystyrene microsphere samples produced by convective self-assembly (CSA). This spectroscopic technique was successfully used to analyze the periodic particle arrays produced by the polystyrene template, yielding a detailed characterization of each sample. The CSA-prepared samples proved to be more uniform across a sample as well as more reproducible than previous sample preparation techniques. For the first time, a detailed characterization and quantitative evaluation of the entire sample has been performed by spectroscopic mapping.