Adsorption of proteins to thin-films of PDMS and its effect on the adhesion of human endothelial cells

This paper describes a simple and inexpensive procedure to produce thin-films of poly(dimethylsiloxane). Such films were characterized by a variety of techniques (ellipsometry, nuclear magnetic resonance, atomic force microscopy, and goniometry) and used to investigate the adsorption kinetics of three model proteins (fibrinogen, collagen type-I, and bovine serum albumin) under different conditions. The information collected from the protein adsorption studies was then used to investigate the adhesion of human dermal microvascular endothelial cells. The results of these studies suggest that these films can be used to model the surface properties of microdevices fabricated with commercial PDMS. Moreover, the paper provides guidelines to efficiently attach cells in BioMEMS devices.Fil: Chumbimuni Torres, Karin Y.. The University of Texas at San Antonio; Estados UnidosFil: Coronado, Ramon E.. The University of Texas at San Antonio; Estados UnidosFil: Mfuh, Adelphe M.. The University of Texas at San Antonio; Estados UnidosFil: Castro Guerrero, Carlos. The University of Texas at San Antonio; Estados UnidosFil: Silva, María Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; ArgentinaFil: Negrete, George R.. The University of Texas at San Antonio; Estados UnidosFil: Bizios, Rena. The University of Texas at San Antonio; Estados UnidosFil: Garcia, Carlos D.. The University of Texas at San Antonio; Estados Unido

Biomechanical structure-function relationships of collagen tissues, B Cell membranes, and amyloid fibers

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.Includes bibliographical references.Mechanical forces are critical to defining the physiological function of biological systems spanning length scales from 1 nm (single molecules) up to 1m (full mammalian systems). This work combines theoretical and experimental mechanics to gain insights into the physiological function of three biological systems at distinct length scales: collagen tissues comprised of wavy fibers (~ 1 mm), B lymphocyte membranes (~ 1 [mu]m), and amyloid protein fibers (~ 1 nm). The initial portion of this thesis addresses the mechanics of fibrous collagen tissues such as ligaments, tendons, and pericardium that serve as load bearing components in biological systems. A novel micromechanical model describing the force-extension of wavy fibers comprising these tissues is integrated with bundle and network frameworks. The developed models accurately predict the mechanical behavior of bundled fiber tissues (i.e ligaments and tendon) and fibrous membranes (i.e. vessel walls and pericardium) and elucidate deformation mechanisms within these tissues. Moving down in length scale, the second part of this thesis employs single cell experiments with optical tweezers to characterize the mechanical behavior of the B cell membrane, which is a critical component of its physiological functions including migration and antigen detection. Our results show that the mechanical properties of the membrane, specifically the effective viscosity of the membrane, evolve upon activation of B cell biochemical machinery. We further identify the presence of receptors in membrane nanotubes conferring B cells with the ability to sense antigen at remote locations. Lastly, this thesis studies the aggregation and underlying structure of amyloid forming proteins by characterizing their physical properties at the fibril and single molecule level. Amyloid formation, which is associated with many diseases including Alzheimer's, results from the aggregation of misfolded proteins. This work combines optical trapping with fluorescence imaging to quantify the physical properties and molecular interactions of amyloid fibers formed from polymorphic variants of the yeast prion protein, Sup35. Our results show that Sup35 polymorphism leads to distinct physical properties of amyloid aggregates. We further subject fibers to unfolding and rupture to elucidate structural details of misfolded Sup35.by Carlos E. Castro.Ph.D

Gibbs-Donnan and specific ion interaction theory descriptions of the effect of ionic strength on proton dissociation of alginic acid

The apparent proton dissociation constants of a commercial alginic acid have been obtained in KNO3 and NaCl at concentrations ranging between 0.01 and 2 mol·L-1. An analysis of the dependence on the ionic strength at a constant value of the dissociation degree was done by means of empirical functions derived from the Gibbs-Donnan formalism for polyelectrolytes and a specific ion interaction theory (SIT). Both functions were able to fit the experimental data, although SIT yielded rather high errors in the fitted parameters due to a problem of multicollinearity, in contrast to the function derived from the Gibbs-Donnan approach.This work was funded by the projects BQU2002-02133 (from the Ministerio de Ciencia y Tecnología of Spain) and PGDIT02TAM10302PR (from the Xunta de Galicia). C.R.C. benefited from a FPU grant of the Ministerio de Educación, Cultura y Deporte of Spain

Efficient multivariable submarine depth-control system design

An efficient solution for the multivariable submarine control design at low-depth conditions under the influence of wave disturbances is presented. The analysis and control design process is carried out under the framework of individual channel analysis and design (ICAD), which is based on the multivariable structure function (MSF). Classical frequency-domain control techniques based on Bode and Nyquist plots are used. Robustness is stated in terms of gain and phase margins. The closed-loop system includes low-order diagonal controllers facilitating its implementation, assessment, and tuning. ICAD discloses new physical insights of the submarine dynamical behaviour. Previous designs based on diagonal controllers consider the input–output channels defined by pairing the bow hydroplane angle with the depth and the stern hydroplane angle with the pitch angle. The alternative input–output pairing leads to unstable closed-loop systems. This phenomenon is associated with hydroplane reverse control. Here it is shown that MSF-based diagonal controllers can be applied effectively for both sets of channel configurations. Emphasis is placed on satisfying design specifications aiming at maintaining the depth low. The solution presented is more feasible and clearer to apply in practice than those so far reported in the literature

Intel Corporation, Guadalajara Design Center

Este reporte redacta las actividades realizadas en la empresa huésped Intel Corporation con el propósito de realizar las actividades relacionadas con el PAP4N01B. Asumí un puesto de becario en el periodo PAP anterior y este periodo mantengo las mismas responsabilidades en el equipo al que me uní inicialmente. Este equipo realiza actividades de empaquetamiento y desarrollo de herramientas internas para la aceleración de la validación de silicios para su lanzamiento al mercado. Este puesto me permite tener contacto con las áreas de calidad, desarrollo e infraestructura, también es mi responsabilidad colaborar con clientes y otros desarrolladores internos. Para llevar a cabo las actividades de desarrollo interactúo en un ambiente interdisciplinario con profesionales de diferentes niveles de antigüedad y ubicados en diferentes partes del mundo, sea Estados Unidos, Israel, Alemania, Malasia y Costa Rica los lugares con oficinas de mayor importancia para la correcta operación del proyecto. En este ambiente logro desarrollar mis habilidades duras, así como mis habilidades blandas para prepararme como profesionista, las actividades realizadas me sirven para reforzar el conocimiento visto en clase y la experiencia práctica me permite identificar mis fortalezas y puntos de mejora.ITESO, A.C

Panel Flutter Analysis and Optimization of Composite Tow Steered Plates

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143015/1/6.2017-1118.pd

Nambu-Goto Strings from SU(N) Born-Infeld model

The spectrum of quenched Yang-Mills theory in the large-N limit displays strings and higher dimensional extended objects. The effective dynamics of string-like excitations is encoded into area preserving Schild action. In this letter, we bridge the gap between SU(N) gauge models and fully reparametrization invariant Nambu-Goto string models by introducing an extra matrix degree of freedom in the Yang-Mills action. In the large-N limit this matrix variable becomes the world-sheet auxiliary field allowing a smooth transition between the Schild and Nambu-Goto strings. The new improved matrix model we propose here can be extended to p-branes provided we enlarge the dimensionality of the target spacetime.Comment: 11pages, no figures, LateX2e; added discussio

Biodegradation of Beta-Blockers and Fluoxetine followed by a Chiral HPLC-FD

Despite of the massive publications concerning pharmaceuticals in the environment, the problematic related with chiral compounds and enantioselective degradation are still largely unknown [1]. Enantiomers have different interactions with enzymes, receptors and other chiral molecules, leading to different biological activities. Thus, biodegradation tends to be enantioselective in contrast to abiotic degradation. However, biodegradation studies regarding enantioselectivity on the process are scarce [2].] MATERIALS AND METHODS [Four beta-blockers: alprenolol (ALP), propranolol (PHO), metoprolol (MET) and atenolol (ATE) and the antidepressant fluoxetine (FX) were enantiomerically separated by a macrocyclic antibiotic vancomycin CSP (ASTEC Chirobiotic V 5µm) under polar organic mode phase (methanol:ethanol:triethylamine:acetic acid.50:50 v/v) and fluorescence detection for enantiomeric fraction quantification. The developed methods were established using a minimal medium inoculated with activated sludge (AS) as a matrix.] RESULTS AND DISCUSSION [The Chirobiotic VTM was able to resolve ALP and PHO as well as MET, ATE and FX in two short runs. A separation factor (α) between 1.12 and 1.34 and resolution (Rs) between 1.30 and 4.35 were obtained. The methods demonstrated to be selective and linear within the range, with detection limits between 2.5 and 10ng/mL. These methods were applied to follow the biodegradation of the target compounds. The biodegradation assays were performed using AS from a municipal WWTP and the results indicate the higher degradation extents for the S- enantiomer forms at initial concentrations tenfold above those found in the environment (10ppm and 5ppm). The same assays were performed at an initial concentration of 1ppm for a singly supplementation and at 0,5ppm for a mixture of compounds, a closer situation to the real environment.] CONCLUSIONS [To our knowledge, chromatographic enantioseparations of the mixture of ALP and PHO and the mixture of MET, FX and ATE using the Chirobiotic™ V, have not been previously reported. The feasibility of this application was confirmed by two biodegradation studies using AS, with S-form being faster degraded, showing stereoselectivity