Calibration of piezoelectric positioning actuators using a reference voltage-to-displacement transducer based on quartz tuning forks

We use a piezoelectric quartz tuning fork to calibrate the displacement of ceramic piezoelectric scanners which are widely employed in scanning probe microscopy. We measure the static piezoelectric response of a quartz tuning fork and find it to be highly linear, non-hysteretic and with negligible creep. These performance characteristics, close to those of an ideal transducer, make quartz transducers superior to ceramic piezoelectric actuators. Furthermore, quartz actuators in the form of a tuning fork have the advantage of yielding static displacements comparable to those of local probe microscope scanners. We use the static displacement of a quartz tuning fork as a reference to calibrate the three axis displacement of a ceramic piezoelectric scanner. Although this calibration technique is a non-traceable method, it can be more versatile than using calibration grids because it enables to characterize the linear and non-linear response of a piezoelectric scanner in a broad range of displacements, spanning from a fraction of a nanometer to hundreds of nanometers. In addition, the creep and the speed dependent piezoelectric response of ceramic scanners can be studied in detail.Comment: 9 pages, 3 figure

Spontaneous deposition of Pt-nanoparticles on HOPG surfaces

Platinum nanoparticles were obtained on glassy carbon (GC) by spontaneous deposition in a 1 mM H2PtCl6 + 0.5 M H2SO4 solution. The structures obtained were characterized using AFM, SEM and cyclic voltammetry in order to study their catalytic activity. AFM imaging shows hemispherical Pt nanoparticles distributed mainly on the polish lines, changing in size with the increasing of time. SEM images showed Pt nanoparticles on the entire exposed surface with different shapes and sizes, in both AFM and SEM dendritic structures were also found, the EDX analysis revealed only the presence of C, O and Pt on the surface. The electrochemical characterization showed an increase in current density with the immersion time and at longer immersion times the voltammetric response was similar to polycrystalline Pt.Fil: Arroyo Gomez, Jose Joaquin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; ArgentinaFil: Garcia, Silvana Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; Argentin

Researching Framework for Simulating/Implementating P Systems

Researching simulation/implementation of membranes systems is very recent. Present literature gathers new publications frequently about software/hardware, data structures and algorithms for implementing P system evolution. In this context, this work presents a framework which goal is to make tasks of researchers of this field easier. Hence, it establishes the set of cooperating classes that form a reusable and flexible design for the customizable evaluation with new data structures and algorithms. Moreover, it includes customizable services for correcting, monitoring and logging the evolution and edition, recovering, automatic generating, persistence and visualizing P systems

Metabolic Remodeling and Mitochondrial Dysfunction in Maladaptive Right Ventricular Hypertrophy Secondary to Pulmonary Arterial Hypertension

Right ventricular dysfunction is the most frequent cause of death in patients with pulmonary arterial hypertension. Although abnormal energy substrate use has been implicated in the development of chronic left heart failure, data describing such metabolic remodeling in failing right ventricular tissue remain incomplete. In the present dissertation we sought to characterize metabolic gene expression changes and mitochondrial dysfunction in functional and dysfunctional RV hypertrophy. Two different rat models of RV hypertrophy were studied. The model of right ventricular failure (SU5416/hypoxia) exhibited a significantly decreased gene expression of peroxisome proliferator-activated receptor- coactivator-1α, peroxisome proliferator- activated receptor-α and estrogen-related receptor-α. The expression of multiple peroxisome proliferator-activated receptor- coactivator-1α target genes required for fatty acid oxidation was similarly decreased. Decreased peroxisome proliferator-activated receptor- coactivator-1α expression was also associated with a net loss of mitochondrial protein and oxidative capacity. Reduced mitochondrial number was associated with a downregulation of transcription factor A, mitochondrial, and other genes required for mitochondrial biogenesis. Electron microscopy demonstrated that, in right ventricular failure tissue, mitochondria had abnormal shape and size. Lastly, respirometric analysis demonstrated that mitochondria isolated from right ventricular failure tissue had a significantly reduced ADP- stimulated (state 3) rate for complex I. Conversely, functional right ventricular hypertrophy in the pulmonary artery banding model showed normal expression of peroxisome proliferator-activated receptor- coactivator-1α, whereas the expression of fatty acid oxidation genes was either preserved or unregulated. Moreover, pulmonary artery banding-right ventricular tissue exhibited preserved transcription factor A mitochondrial expression and mitochondrial respiration despite elevated right ventricular pressure-overload. We conclude that right ventricular dysfunction, but not functional right ventricular hypertrophy in rats, demonstrates a gene expression profile compatible with a multilevel impairment of fatty acid metabolism and significant mitochondrial dysfunction, partially independent of chronic pressure-overload

Solving complex problems with a bioinspired model

Membrane systems are parallel and bioinspired systems which simulate membranes behavior when processing information. As a part of unconventional computing, P-systems are proven to be effective in solvingcomplexproblems. A software technique is presented here that obtain good results when dealing with such problems. The rules application phase is studied and updated accordingly to obtain the desired results. Certain rules are candidate to be eliminated which can make the model improving in terms of time

Rasgando la Piel: Tatuajes, Cuerpos y Significados

La modificacion corporal mediante el tatuaje se realiza con diferentes propositos y distintas motivaciones. Esta practica es muy comun en nuestra sociedad puertorriquena; no obstante, ha sido escasamente estudiada. Como resultado de esto, se desarrollo una investigacion con los objetivos de explorar la constitucion narrativa, el cambio de significado personal y social, y la percepcion de trabajadores/as sociales que subyace a la practica de tatuarse el cuerpo. Estos aspectos fueron estudiados entre personas tatuadas, no tatuadas y trabajadores/as sociales mediante la implantacion de un diseno exploratorio. Se espera que los hallazgos encontrados logren contribuir al interes en la realizacion de futuras investigaciones sobre el tipo de estigma relacionado al tatuaje y las repercusiones sociales que trae consigo

Networks of polarized evolutionary processors are computationally complete

ABSTRACT In this paper, we consider the computational power of a new variant of networks of evolutionary processors which seems to be more suitable for a software and hardware implementation. Each processor as well as the data navigating throughout the network are now considered to be polarized. While the polarization of every processor is predefined, the data polarization is dynamically computed by means of a valuation mapping. Consequently, the protocol of communication is naturally defined by means of this polarization. We show that tag systems can be simulated by these networks with a constant number of nodes, while Turing machines can be simulated, in a time-efficient way, by these networks with a number of nodes depending linearly on the tape alphabet of the Turing machine

Biofijación de CO2, NO y SO2 presentes en los gases de plantas termoeléctricas utilizando microalgas

83 páginas. Maestría en Ciencias e Ingeniería Ambientales.En esta investigación, los efectos que tienen los gases óxido nítrico (NO) y dióxido de azufre (SO2) en la fijación de dióxido de carbono (CO2) durante el crecimiento de la microalga Senedesmus dimorphus fueron hechos. La microalga del presente estudio fue aislada del lago de Chapultepec en la Ciudad de México. Los experimentos fueron llevados a cabo en tres reactores del tipo Airlift que fueron suministrados con aire y cuatro diferentes mezclas de gases: (aire – 12% CO2), (aire – 12% CO2 – 100 ppm NO), (aire – 12% CO2 – 60 ppm SO2) y (aire – 12% CO2 – 100 ppm NO – 60 ppm SO2). Las mezclas utilizadas fueron hechas con una composición similar a la composición de las emisiones de una Planta Termoeléctrica. En este estudio se encontró que la microalga S. dimorphus fue capaz de utilizar el NO como fuente de nitrógeno para la formación de biomasa, ya que el cultivo que se alimentó con la mezcla de 12% CO2 y 100 ppm NO mostro la mayor eficiencia de utilización de CO2 (0.2 %) y la mayor velocidad de fijación de CO2 (0.051 g CO2 L-1 d-1). Así mismo, la microalga asimiló mejor el NO que los NO3- que son utilizados en los medios de cultivo comerciales. Sin embargo, la adición de NO redujo el tiempo del período de mantenimiento celular después de que se alcanzó la máxima concentración de biomasa. En los experimentos la adición de SO2 a los reactores mostró un efecto inhibitorio en el crecimiento de la microalga y con esto también la eficiencia de utilización de CO2 (0.11%).In this research, the effects of the nitric oxide (NO) and sulfur dioxide (SO2) gases in the fixation of carbon dioxide (CO2) during the growth of the microalgae Senedesmus dimorphus were made. The microalgae of this study were isolated from the Chapultepec Lake in Mexico City. The experiments were conducted in three Airlift reactors which were supplied with air and four different gas mixtures: (air - 12% CO2), (air - 12% CO2 - 100 ppm NO), (air - 12% CO2 - 60 ppm SO2) and (air - 12% CO2 - 100 ppm NO - 60 ppm SO2). The mixtures used were made with a similar composition to the composition of emissions from a power plant. In this study, the microalga S. dimorphus was able to use the NO as a the nitrogen source for its biomass formation because the culture being fed with the mixture of 12% CO2 and 100 ppm showed an increased efficiency of use of CO2 (0.2%) and also an increased CO2 fixation rate (CO2 0.051 g L-1 d-1). Also, the microalgae assimilated NO better than NO3- which was used in commercial culture media. However, the addition of NO reduced the period of time of cell maintenance after the maximum concentration of biomass was reached. In these experiments, the addition of SO2 gas to the reactors showed an inhibitory effect on the growth of the microalgae, and thus also the efficiency of utilization of CO2 (0.11%)

Simulating Metabolic Processes Using an Architecture Based on Networks of Bio-inspired Processors.

In this work, we propose the Networks of Evolutionary Processors (NEP) [2] as a computational model to solve problems related with biological phenomena. In our first approximation, we simulate biological processes related with cellular signaling and their implications in the metabolism, by using an architecture based on NEP (NEP architecture) and their specializations: Networks of Polarized Evolutionary Processors (NPEP) [1] and NEP Transducers (NEPT) [3]. In particular, we use this architecture to simulate the interplay between cellular processes related with the metabolism as the Krebs cycle and the malate-aspartate shuttle pathway (MAS) both being altered by signaling by calcium