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Estudio sobre los sistemas iterados de funciones contractivas
Get PDF"Puesto que una tarea importante en geometria fractal es el estudio de los conjuntos invariantes compactos y sus propiedades, con este fin se han desarrollado teorías bien fundamentadas acerca de estos conjuntos. Un conjunto invariante compacto comunmente se le conoce como conjunto fractal. En 1975 B. Mandelbrot fué el primero en dar una definición a estos conjuntos y los define de la manera siguiente: Un conjunto fractal es un conjunto no navío que es autosimilar y cuya dimensión de Hausdorff-Besicovith excede a su dimensión topológica. Posteriormente en 1981, J.E. Hutchinson fue el
primer matemático en plantear una teoría para estudiar estos conjuntos en Rn, a los que el llamó estrictamente autosimilares, introduciendo con ello el concepto de sistema iterado de funciones [22]. Posterior a él, M.F. Barnsley generaliza las teorías de J.E. Hutchinson y hacia 1998 populariza el concepto de sistema iterado de funciones [9]. A partir de esto, el Teorema de Existencia y Unicidad para conjuntos fractales propuesto por M.F. Barnsley ha sido objeto de estudio. En esta tesis presentamos el caso especial de la construcción de un conjunto invariante compacto por medio de iteraciones
de orden fraccionario, así como una proposición y establecemos cuatro proposiciones entorno a la construcción de sistemas iterados de funciones, y las condiciones a estos sistemas para que los conjuntos invariantes compactos asociados a estas clases de SIF’s presenten la autosemejanza topológica.""Since an important task in fractal geometry is the study of compact invariant sets and their properties, to that end well-founded theories about these sets have been developed. A compact invariant set is commonly referred to as a fractal set. In 1975, B. Mandelbrot was the first to give a definition to these sets. And it defines it as follows: A fractal set is a non-empty set that is self-similar and whose Hausdorff-Besicovitch dimension exceeds it’s topological dimension [1]. Subsequently in 1981, J.E. Hutchinson
was the first mathematician to propose a theory to study these sets in Rn, which he call strictly self-similar, thus introducing the concept of iterated system of functions [22]. After the, M.F. Barnsley generalizes the theories of J.E. Hutchinson and towards 1998 popularizes the concept of iterated system of functions [9]. Starting from this, the existence and uniqueness theorem of M.F. Barnsley has been the subject of study. In this thesis we present the special case of the construction of a compact invariant set by means of fractional order iterations, as well as a proposition and we establish four propositions surrounding the construction of iterated systems of functions, and the conditions to these systems so that the associated compact invariant sets to these classes of SIF’s present the topological self-similarity.
Dynamic infrared thermography of nanoheaters embedded in skin-equivalent phantoms
Get PDF"Nanoheaters are promising tools for localized photothermal therapy (PTT) of malignant cells. The anisotropic AuNPs present tunable surface plasmon resonances (SPR) with ideal NIR optical response to be applied as theranostic agents. To this purpose, nanoparticles with branches are suitable because of the electromagnetic field concentrated at their vertices. We standardized a protocol to synthesize multibranched gold nanoparticles (MB-AuNPs) by the seed-growth method and found a size-seed dependence tunability on the hierarchy of branching. Once the optical response is evaluated, we tested the temporal stability as nanoheaters of the MB-AuNPs immersed in skin-equivalent phantoms by dynamic infrared thermography (DIRT). The most suited sample presents a concentration of 5.2 x 10(8) MB-AuNPs/mL showing good thermal stability with Delta T = 4.5 degrees C, during 3 cycles of 10 min at 785 nm laser irradiation with power of 0.15 W. According to these results, the MB-AuNPs are suitable nanoheaters to be tested for PTT in more complex models.
Antioxidant activity and in vitro antiglycation of the fruit of Spondias purpurea
Get PDF"Hyperglycemia in diabetes mellitus causes irreversible life-threatening micro- and macrovascular complications. There is evidence that the glycation reaction leads to a chemical modification of the proteins contributing to the complications of diabetes. It is known that advanced glycation end products (AGEs) are formed by glycation and oxidation reactions called glycoxidation. CML, a nonfluorescent AGE, has become a biomarker of glycoxidative damage; other AGEs appear to induce oxidative stress, which results in cytotoxicity. To determine antioxidant activity, the FRAP, DPPH, and TEAC tests were used, as well as the polyphenols content using Folin-Ciocalteu’s method. To evaluate the antiglycation activity, the BSA/glucose system was used, and the fructosamine concentration, protein carbonyl content, thiol, and CML groups were determined. The results obtained show that the hexane extract of the fruit of Spondias purpurea (CFH) effectively inhibits the glycation reaction, in addition to increasing the thiol groups and decreasing levels of fructosamine, protein carbonyl, and CML. In addition, CFH presented significant antioxidant activity. CFH inhibits the glycation reaction; therefore, it can help prevent complications related to AGEs in diabetes mellitus; it also reduces oxidative stress and is effective in protecting proteins from oxidative damage.
Atomic surface segregation and structural characterization of PdPt bimetallic nanoparticles
Get PDF"Bimetallic nanoparticles are of interest since they lead to many interesting electrical, chemical, catalytic, and optical properties. They are particularly important in the field of catalysis since they show superior catalytic properties than their monometallic counterparts. The structures of bimetallic nanoparticles depend mainly on the synthesis conditions and the miscibility of the two components. In this work, PdPt alloyed-bimetallic nanoparticles (NPs) were synthesized through the polyol method, and characterized using spherical aberration (Cs) corrected scanning transmission electron microscopy (STEM). High-angle annular dark-field (HAADF)-STEM images of bimetallic nanoparticles were obtained. The contrast of images shows that nanoparticles have an alloy structure with an average size of 8.2 nm. Together with the characterization of nanoparticles, a systematic molecular dynamics simulations study focused on the structural stability and atomic surface segregation trends in 923-atom PdPt alloyed-bimetallic NPs was carried out.
Characterization of the kinetic arrest of martensitic transformation in Ni45Co5Mn36.8In13.2 melt-spun ribbons
Get PDF"The kinetic arrest (KA) of martensitic transformation (MT) observed in Ni45Co5Mn36.8In13.2 melt-spun ribbons has been studied. These alloy ribbons show an ordered columnar-like grain microstructure with the longer grain axis growing perpendicular to ribbon plane and transform martensitically from a single austenitic (AST) parent phase with the L21-type crystal structure to a monoclinic incommensurate 6 M modulated martensite (MST). Results show that the volume fraction of austenite frozen into the martensitic matrix is proportional to the applied magnetic field. A fully arrest of the structural transition is found for a magnetic field of 7 T. The metastable character of the non-equilibrium field-cooled glassy state was characterized by introducing thermal and magnetic field fluctuations or measuring the relaxation of magnetization. The relaxation of magnetization from a field-cooled kinetically arrested state at 5 and 7 T follows the Kohlrausch–Williams–Watts (KWW) stretched exponential function with a ? exponent around 0.95 indicating the weak metastable nature of the system under the strong magnetic fields. The relationship between the occurrence of exchange bias and the frozen fraction of AST into the MST matrix was studied.
Candida glabrata’s genome plasticity confers a unique pattern of expressed cell wall proteins
Get PDF"Candida glabrata is the second most common cause of candidemia, and its ability to adhere to different host cell types, to microorganisms, and to medical devices are important virulence factors. Here, we consider three characteristics that confer extraordinary advantages to C. glabrata within the host. (1) C. glabrata has a large number of genes encoding for adhesins most of which are localized at subtelomeric regions. The number and sequence of these genes varies substantially depending on the strain, indicating that C. glabrata can tolerate high genomic plasticity; (2) The largest family of CWPs (cell wall proteins) is the EPA (epithelial adhesin) family of adhesins. Epa1 is the major adhesin and mediates adherence to epithelial, endothelial and immune cells. Several layers of regulation like subtelomeric silencing, cis-acting regulatory regions, activators, nutritional signaling, and stress conditions tightly regulate the expression of many adhesin-encoding genes in C. glabrata, while many others are not expressed. Importantly, there is a connection between acquired resistance to xenobiotics and increased adherence; (3) Other subfamilies of adhesins mediate adherence to Candida albicans, allowing C. glabrata to efficiently invade the oral epithelium and form robust biofilms. It is noteworthy that every C. glabrata strain analyzed presents a unique pattern of CWPs at the cell surface.
Synthesis of ZnMn2O4 nanoparticles by a microwave-assisted colloidal method and their evaluation as a gas sensor of propane and carbon monoxide
Get PDF"Spinel-type ZnMn2O4 nanoparticles were synthesized via a simple and inexpensive microwave-assisted colloidal route. Structural studies by X-ray diffraction showed that a spinel crystal phase of ZnMn2O4 was obtained at a calcination temperature of 500 °C, which was confirmed by Raman and UV-vis characterizations. Spinel-type ZnMn2O4 nanoparticles with a size of 41 nm were identified by transmission electron microscopy. Pellet-type sensors were fabricated using ZnMn2O4 nanoparticles as sensing material. Sensing measurements were performed by exposing the sensor to different concentrations of propane or carbon monoxide at temperatures in the range from 100 to 300 °C. Measurements performed at an operating temperature of 300 °C revealed a good response to 500 ppm of propane and 300 ppm of carbon monoxide. Hence, ZnMn2O4 nanoparticles possess a promising potential in the gas sensors field.
Physicochemical characterization, elemental speciation and hydrogeochemical modeling of Santa Lucía peloid used for therapeutic uses
No full text"Santa Lucia peloid is a sediment, extracted from salt mines, used in pelotherapy in Cuban primary health care services. Therefore, in addition to classical quality control analyses of total metal concentrations in sediments, speciation and complementary analyses are required to understand potential geochemical element availability for their use in human health.
The present study was conducted to characterize the Santa Lucia peloid, based on the total metal content and geochemical speciation of major elements and transition metals (Cr, Cu, Fe, Ni, Mn, Pb and Zn), using a sequential extraction procedure and inductively couple plasma emission techniques. In order to predict the distribution of majoritarian and trace elements in different geochemical fractions, the physicochemical parameters, the particle size (electronic microscopy), mineralogy (X-ray diffraction), and the hydrogeochemical models (Pourbaix phase diagrams) were used. The results showed that the predominant cation was Na with high mobility and exchange capacity; meanwhile most of the trace elements studied (Cr, Pb, Ni) in this investigation appeared in the less mobile fractions, which suggested low availability in the sediment, under the studied conditions. The findings were useful to predict the behavior of the metals regarding solubility, potential motility and availability in the sediment, and it was concluded that most of the metals are strongly retained in the peloid and that sediment was considered as non-polluted, according to USEPA normative.
Dopaje con nitrógeno y funcionalización in-situ de nanolistones grafíticos y su aplicación en sensores de etanol
Get PDF"La detección y medición digital de propiedades físicas y moleculares es hoy en día
una de las necesidades esenciales para la implementación del Internet de las
cosas, cuya meta principal es la integración de los dispositivos electrónicos en la
vida cotidiana. La electrónica orgánica se acopla perfectamente a este concepto
por contar con características naturalmente viables para este tipo de aplicaciones.
Las nanoestructuras de carbono, están generando una alta expectativa en la
elaboración de sistemas electrónicos complejos, principalmente debido a su
simple fabricación que permite el control de sus escalas nanométricas a través de
las condiciones experimentales de síntesis. En este trabajo se sintetizaron
nanolistones grafíticos usando la metodología de deposición química de vapores
asistida por aerosol (AA-CVD). Tres diferentes precursores de nitrógeno se
utilizaron variando dos porcentajes de concentración (Piridina, pirazina y pirrol a
1% y 2% respectivamente), permitiendo diferentes dopajes de átomos de
nitrógeno en la red de grafito. Imágenes de SEM demostraron una alta cantidad de
nanolistones con poco material amorfo y los espectros de XPS se comprueba la
existencia de nitrógeno enlazado con el carbono presente en los nanolistones,
espectroscopía Raman indicó que las muestras con mejor nivel de grafitización
son las elaboradas con pirazina. Algunas de las muestras obtenidas en la síntesis
fueron empleadas para la fabricación de sensores de electrodos interdigitados. Un
parámetro importante para el los sensores es la dispersión de las muestras sobre
la superficie del electrodo y esto se observó usando microscopía óptica. Estos
electrodos fueron expuestos al interior de una cámara con una concentración
conocida de vapores de alcohol y el cambio de resistencia se midió a través de
una interfaz de comunicación con Arduino.""Nowadays, detection and digital measurement of physical and molecular properties
is becoming an essential part for the implementation of the so-called Internet of
Things, which principal approach is to fully integrate the electronic devices in the
daily life. Organic electronics is one of the best candidates to this approach
because of its natural characteristics. Carbon nanostructures are creating a high
expectative around its use in complex electronic systems, mainly due to its simple
fabrication, which allows controlling its nanometric scale via the experimental
parameters and synthesis conditions. In this work, graphene nanoribbons were
synthetized by using the aerosol assisted chemical vapor deposition method (AACVD).
Three different nitrogen precursors were used and two different
concentrations (pyridine, pyrazine and pyrrole at 1% and 2% respectively), allowing
different N-doping onto the graphite lattice. SEM measurements demonstrated a
high presence of carbon nanoribbons and the XPS spectra showed the presence
of nitrogen atoms bonded to the carbon atoms in the nanoribbons. Raman
spectroscopy indicated that the samples with the highest level of graphitization
were those synthesized with pyrazine. Some of the synthesized samples were
used for the fabrication of interdigitated electrodes sensors. An important
parameter for the gas sensor was the nanostructure dispersions on the electrode
and this was observed using optical microscopy. These electrodes were exposed
to a chamber filled with a known concentration of ethanol vapor and the resistance
changes were measured using an Arduino interface.
Efecto de la proteína de amaranto en ratones con obesidad inducida por dieta: explorando el mecanismo de acción en tejido adiposo y glicoproteínas de plasma
Get PDF"El amaranto ha sido propuesto como un alimento nutracéutico, pero su función en enfermedades relacionadas con la obesidad no ha sido comprendida del todo; además la mayoría de los estudios in vivo que se encuentran en la literatura evalúan el efecto del aceite de amaranto en enfermedades cardiovasculares. Por otro lado, la proteína del grano de amaranto, de acuerdo a estudios previos, ha demostrado tener in vitro otra clase de efectos terapéuticos relacionados con el metabolismo de carbohidratos. El objetivo de este trabajo fue producir un aislado proteínico de amaranto de bajo costo y analizar su efecto en los perfiles lipídicos y de resistencia a la insulina en ratones con obesidad inducida por dieta, utilizando proteína de soya como referencia, se exploró el mecanismo de acción en tejido adiposo utilizando la medición de expresión génica y un análisis glicoproteómico de plasma sanguíneo. Ratones C57BL/6 fueron alimentados durante 8 semanas con una dieta regular o una dieta hipercalórica, además de consumir aislado de proteína de amaranto o soya por vía oral a una dosis de 10 mg/Kg. Las variables que se evaluaron fueron los cambios en el peso corporal, tejido adiposo, colesterol total, triglicéridos, insulina, una curva de tolerancia a la glucosa, expresión de genes relacionados con el metabolismo de lípidos y el estado inflamatorio, así como del glicoproteoma de plasma de cada grupo. Los resultados demostraron que la proteína de amaranto induce un decremento de la insulina plasmática en los ratones que fueron alimentados con una dieta regular (0.09 ng/ml vs. 0.39 ng/ml), además de que en ratones con dieta hipercalórica induce un descenso de los triglicéridos (144 mg/dl vs. 125.1 mg/dl). En adición, se encontró una expresión menor de los genes Res, Tnf-α, Fasn, Lep y Fabp4 en este grupo, demostrando una inhibición del estado inflamatorio y de la hidrólisis de lípidos. El análisis glicoproteómico confirmó el involucramiento de lipoproteínas como parte del efecto y mostró otras proteínas afectadas por los tratamientos incluyendo glicoproteínas Hb y serpinas. Estos resultados podrían conducir a nuevos mecanismos de acción mediante los cuales el amaranto ejerce su acción biológica. La proteína de amaranto fue capaz de mejorar la hiperlipidemia e hiperinsulinemia producida por la obesidad inducida por dieta.""Amaranth has been claimed as nutraceutical food, but its function on obesityrelated
disorder is still not fully understood; in addition, most in vivo studies in
literature evaluate the effect of amaranth oil on cardiovascular disease. On the
other hand, amaranth seed protein, according to previous studies, has been
demonstrated to have other therapeutic effects related to the carbohydrates
metabolism. The aim of this work was to produce a cost-effective amaranth protein
isolate and analyze its effect on lipid and insulin resistance profiles in diet-induced
obese mice, using soybean protein as the reference, the mechanism of action in
adipose tissue was explored using gene expression assessment and blood plasma
glycoproteomic analysis.
C57BL-6 mice were fed for 8 weeks with regular or high-fat diet along with
amaranth or soybean protein isolates at 10 mg/Kg. Changes in body weight,
adipose tissue, total cholesterol, triglycerides, insulin, glucose tolerance test,
expression of lipid metabolism-related and inflammation-state genes, and the
differences on the plasma glycoproteome of each group were measured as
variable of response. Results demonstrated that amaranth protein induced a
decrease in plasma insulin in mice fed with a regular diet (0.09 ng/ml vs. 0.39
ng/ml), whereas a decrease in triglycerides was observed in mice fed with high-fat
diet (144 mg/dl vs. 125.1 mg/dl).; furthermore lower expression of Res, Tnf-α,
Fasn, Lep and Fabp4 genes in this group, demonstrated inhibition of inflammation
state and lipids hydrolysis. The glycoproteomic analysis confirmed the inclusion of
lipoproteins as part of the effect and showed other proteins affected by the
treatments involving Hb and serpin proteins. These results could lead to new
possible mechanisms of action by which amaranth exert their biological function.
Amaranth protein consumption was able to improve the hyperlipidemia and
hyperinsulinemia produced by the diet-induced obesity. The present study has
demonstrated that amaranth protein, but not soybean protein, improved the obesity
condition in mice