Studies on Laser Induced and RF Sputtered Plasma using Optical Emission Spectroscopy and Langmuir Probe

The main objective of the present study is to understand different mechanisms involved in the production and evolution of plasma by the pulsed laser ablation and radio frequency magnetron sputtering. These two methods are of particular interest, as these are well accomplished methods used for surface coatings, nanostructure fabrications and other thin film devices fabrications. Material science researchers all over the world are involved in the development of devices based on transparent conducting oxide (TCO) thin films. Our laboratory has been involved in the development of TCO devices like thin film diodes using zinc oxide (ZnO) and zinc magnesium oxide (ZnMgO), thin film transistors (TFT's) using zinc indium oxide and zinc indium tin oxide, and some electroluminescent (EL) devices by pulsed laser ablation and RF magnetron sputtering.In contrast to the extensive literature relating to pure ZnO and other thin films produced by various deposition techniques, there appears to have been relatively little effort directed towards the characterization of plasmas from which such films are produced. The knowledge of plasma dynamics corresponding to the variations in the input parameters of ablation and sputtering, with the kind of laser/magnetron used for the generation of plasma, is limited. To improve the quality of the deposited films for desired application, a sound understanding of the plume dynamics, physical and chemical properties of the species in the plume is required. Generally, there is a correlation between the plume dynamics and the structural properties of the films deposited. Thus the study of the characteristics of the plume contributes to a better understanding and control of the deposition process itself. The hydrodynamic expansion of the plume, the composition, and SIze distribution of clusters depend not only on initial conditions of plasma production but also on the ambient gas composition and pressure. The growth and deposition of the films are detennined by the thermodynamic parameters of the target material and initial conditions such as electron temperature and density of the plasma.For optimizing the deposition parameters of various films (stoichiometric or otherwise), in-situ or ex-situ monitoring of plasma plume dynamics become necessary for the purpose of repeatability and reliability. With this in mind, the plume dynamics and compositions of laser ablated and RF magnetron sputtered zinc oxide plasmas have been investigated. The plasmas studied were produced at conditions employed typically for the deposition of ZnO films by both methods. Apart from this two component ZnO plasma, a multi-component material (lead zirconium titanate) was ablated and plasma was characterized.

Studies on Heat Diffusion in Selected Conducting Polymers using Probe Beam Deflection and Photoacoustic Techniques

In the present study, radio frequency plasma polymerization technique is used to prepare thin films of polyaniline, polypyrrole, poly N-methyl pyrrole and polythiophene. The thermal characterization of these films is carried out using transverse probe beam deflection method. Electrical conductivity and band gaps are also determined. The effect of iodine doping on electrical conductivity and the rate of heat diffusion is explored.Bulk samples of poyaniline and polypyrrole in powder form are synthesized by chemical route. Open photoacoustic cell configuration is employed for the thermal characterization of these samples. The effect of acid doping on heat diffusion in these bulk samples of polyaniline is also investigated. The variation of electrical conductivity of doped polyaniline and polypyrrole with temperature is also studied for drawing conclusion on the nature of conduction in these samples. In order to improve the processability of polyaniline and polypyrrole, these polymers are incorporated into a host matrix of poly vinyl chloride. Measurements of thermal diffusivity and electrical conductivity of these samples are carried out to investigate the variation of these quantities as a function of the content of polyvinyl chloride.

Energy Management in Wireless Sensor Networks: A Crosslayer,Channel Adaptive Approach Towards Performance Optimization

The proliferation of wireless sensor networks in a large spectrum of applications had been spurered by the rapid advances in MEMS(micro-electro mechanical systems )based sensor technology coupled with low power,Low cost digital signal processors and radio frequency circuits.A sensor network is composed of thousands of low cost and portable devices bearing large sensing computing and wireless communication capabilities. This large collection of tiny sensors can form a robust data computing and communication distributed system for automated information gathering and distributed sensing.The main attractive feature is that such a sensor network can be deployed in remote areas.Since the sensor node is battery powered,all the sensor nodes should collaborate together to form a fault tolerant network so as toprovide an efficient utilization of precious network resources like wireless channel,memory and battery capacity.The most crucial constraint is the energy consumption which has become the prime challenge for the design of long lived sensor nodes.

Production of carbon nanotubes by PECVD and their applications to supercapacitors

Màster en Nanociència i Nanotecnologia

Fabrication of a quantum well heterostructure based on plasma polymerized aniline and its characterization using STM/STS

Two-dimensional electronic systems play a crucial role in modern electronics and offer a multitude of opportunities to study the fundamental phenomena at low dimensional physics. A quantum well heterostructure based on polyaniline (P) and iodine doped polyaniline (I) thin films were fabricated using radio frequency plasma polymerization on indium tin oxide coated glass plate. Scanning probe microscopy and scanning electron microscopy studies were employed to study the morphology and roughness of the polymer thin films. Local electronic density of states (LDOS) of the P–I–P heterostructures is probed using scanning tunnelling spectroscopy (STS). A step like LDOS is observed in the P–I–P heterostructure and is attributed to the quantum well confinement of electrons in the polymer heterostructure.

Large enhanced dielectric permittivity in polyaniline passivated core-shell nano magnetic iron oxide by plasma polymerization

Commercial samples of Magnetite with size ranging from 25–30nm were coated with polyaniline by using radio frequency plasma polymerization to achieve a core shell structure of magnetic nanoparticle (core)–Polyaniline (shell). High resolution transmission electron microscopy images confirm the core shell architecture of polyaniline coated iron oxide. The dielectric properties of the material were studied before and after plasma treatment. The polymer coated magnetite particles exhibited a large dielectric permittivity with respect to uncoated samples. The dielectric behavior was modeled using a Maxwell–Wagner capacitor model. A plausible mechanism for the enhancement of dielectric permittivity is proposed

Studies on the interaction of two level atoms with quantized electromagnetic field

The present study described about the interaction of a two level atom and squeezed field with time varying frequency. By applying a sinusoidal variation in the frequency of the field, the randomness in population inversion is reduced and the collapses and periodic revivals are regained. Quantum optics is an emerging field in physics which mainly deals with the interaction of atoms with quantised electromagnetic fields. Jaynes-Cummings Model (JCM) is a key model among them, which describes the interaction between a two level atom and a single mode radiation field. Here the study begins with a brief history of light, atom and their interactions. Also discussed the interaction between atoms and electromagnetic fields. The study suggest a method to manipulate the population inversion due to interaction and control the randomness in it, by applying a time dependence on the frequency of the interacting squeezed field.The change in behaviour of the population inversion due to the presence of a phase factor in the applied frequency variation is explained here.This study also describes the interaction between two level atom and electromagnetic field in nonlinear Kerr medium. It deals with atomic and field state evolution in a coupled cavity system. Our results suggest a new method to control and manipulate the population of states in two level atom radiation interaction,which is very essential for quantum information processing.We have also studied the variation of atomic population inversion with time, when a two level atom interacts with light field, where the light field has a sinusoidal frequency variation with a constant phase. In both coherent field and squeezed field cases, the population inversion variation is completely different from the phase zero frequency modulation case. It is observed that in the presence of a non zero phase φ, the population inversion oscillates sinusoidally.Also the collapses and revivals gradually disappears when φ increases from 0 to π/2. When φ = π/2 the evolution of population inversion is identical to the case when a two level atom interacts with a Fock state. Thus, by applying a phase shifted frequency modulation one can induce sinusoidal oscillations of atomic inversion in linear medium, those normally observed in Kerr medium. We noticed that the entanglement between the atom and field can be controlled by varying the period of the field frequency fluctuations. The system has been solved numerically and the behaviour of it for different initial conditions and different susceptibility values are analysed. It is observed that, for weak cavity coupling the effect of susceptibility is minimal. In cases of strong cavity coupling, susceptibility factor modifies the nature in which the probability oscillates with time. Effect of susceptibility on probability of states is closely related to the initial state of the system.

Revisión sistemática de la literatura: efecto de la radiofrecuencia como tratamiento de la lipodistrofia ginecoide (celulitis)

Introducción: La lipodistrofia ginecoide, es una condición de la piel distintiva del sexo femenino, estéticamente no aceptada y uno de los principales motivos de consulta en la Medicina Estética. Uno de los equipos médicos-estéticos más utilizados en su tratamiento es la radiofrecuencia, sin embargo su aplicación no siempre lleva a resultados satisfactorios para los pacientes. Métodos: Revisión sistemática de la literatura de artículos obtenidos a partir de bases de datos y búsqueda manual en revistas de dermatología estética entre los años 2004 y 2010 que suministraran la mejor evidencia. Se realizó evaluación de calidad metodológica y los estudios incluidos se organizaron en tablas de evidencia. Resultados: De 38 estudios, se seleccionaron 17 artículos. Los estudios disponibles fueron clasificados según nivel de evidencia como IIA, IB y IIB. Se encontró concordancia en resultados histológicos, evidenciando por aumento de lipólisis, cambios estructurales del adipocito y aumento del colágeno dérmico. La mejoría de la apariencia, fue similar con los diferentes tipos de radiofrecuencia. La disminución de la circunferencia parece ser dependiente del número de sesiones realizadas. Los efectos secundarios principales son eritema y equimosis. Las complicaciones están relacionadas con equipos combinados. No hay evidencia de resultados perdurables en el tiempo. Conclusión: Primera revisión sistemática de la literatura sobre los efectos de la radiofrecuencia en la lipodistrofia ginecoide. La radiofrecuencia sola o combinada es una tecnología segura y efectiva para el manejo de la lipodistrofia ginecoide. La presencia de complicaciones es operario dependiente. Es necesaria la realización de estudios que permitan mayor nivel de evidencia.

Tecnología RFID en Colombia, un negocio con muchas oportunidades

Este trabajo busca identificar y definir porque la tecnología RFID puede ser un buen negocio de oportunidad en el mercado Colombiano, cada vez esté, está más enfocado en generar procesos de mejora continua que produzcan eficiencia al interior de las organizaciones, actualmente el uso de la tecnología es una herramienta clave para que las organizaciones se mantengan a la vanguardia. Con base en el estudio vemos que la tecnología RFID, genera eficiencia en el flujo de la información, mejora el control de inventarios y genera seguridad en estos, además de la disminución en los procesos y operaciones, e incrementa la velocidad en la toma de decisiones, por otro lado existe un mercado a explotar que es el de los hoteles, en la medida en que estos pueden controlar sus inventarios de objetos como sabanas, cobijas, etc. Evitando perder estos productos por robos. Un problema de esta tecnología son los altos costos, que impiden que empresas medianas y pequeñas puedan invertir en estos procesos.

Caracterización de las variantes anatómicas de las venas pulmonares en pacientes candidatos a aislamiento de venas pulmonares en Colombia

Introducción y objetivos: El conocimiento de la anatomía de las venas pulmonares y de la aurícula izquierda es fundamental para la planeación y prevención de posibles complicaciones durante la ablación de las venas pulmonares, procedimiento realizado para el manejo de la fibrilación auricular. Este estudio pretende caracterizar la anatomía (tamaño y forma) de las venas pulmonares y determinar las variantes anatómicas más comunes de las mismas. Métodos: Se analizaron 277 estudios de angioresonancia tridimensional y tomografía computarizada realizados previo al procedimiento de aislamiento de venas pulmonares. Se evaluaron los diámetros de la aurícula izquierda, de los ostia de las venas pulmonares y se determinaron la presencia de venas pulmonares comunes, accesorias y ramificaciones tempranas. Resultados: 75% de nuestros pacientes presentaron la anatomía normal de dos venas pulmonares derechas y dos izquierdas. En un 10,1% de los casos se encontraron venas supernumerarias y en un 11,2% se encontró un tronco común. En un 61% de los pacientes se encontraron ramas ostiales, las cuales en un 39,4% de los casos se presentaron en la vena pulmonar inferior derecha. Conclusiones: La evaluación de la morfología de la aurícula derecha y las venas pulmonares por medio de angioresonancia o tomografía computarizada, es necesaria para la realización de ablación por radiofrecuencia dada la alta frecuencia de variantes anatómicas y presencia de ramas ostiales.

Análisis de los componentes de la cadena de suministro y su relación con el desempeño superior de la organización en el sector manufacturero

En este documento se evidencia como el desempeño organizacional de una empresa, entendido como el rendimiento superior de la misma, se ve modificado por las prácticas o metodologías utilizadas, aplicadas e integradas a cada uno de los componentes de la Cadena de suministros. Es así que el propósito principal es demostrar cual es la relación entre los componentes de la Cadena de Suministros y su gestión sobre los rendimientos económicos de la empresa. De esa manera se encontraron múltiples actividades que toman lugar en los procesos característicos de cada uno de los componentes de la cadena de suministros y que al final nos presentan una variabilidad sobre los rendimientos de la empresa. Cabe recalcar que la investigación se realizó con respecto a empresas pertenecientes al sector manufacturero y abarca una buena parte de este. La importancia que tiene la investigación, es el haber entregado como resultado, el conocimiento sobre algunas de las practicas más utilizadas en el sector en cada uno de sus componentes, lo cual hace de la Cadena de suministros, un factor por excelencia para ser tratado e implementado con el fin de alcanzar mayores rendimientos económicos a nivel de empresa. En la investigación se utilizaron los casos de empresas reales tanto nacionales como internacionales y se encontraron situaciones claves que evidenciaban la hipótesis de la relación entre la cadena de suministros y el desempeño organizacional. Es por ello, que si bien es ahora cierto, que las actividades desarrolladas en los componentes de la Cadena de Suministros de las empresas influyen en el incremento de los rendimientos, es importante que las empresas conozcan de esta información para tener una idea de cómo desarrollar ventajas competitivas que los posicionen como empresa y les genere entonces mayores rendimientos, o por el contrario, les genere ahorros en costos y por ende altos beneficios y nuevas inversiones en prácticas que a la larga volverá a la empresa en un organismo eficientes y próspero.

RF Energy Harvesting in WSNs

As a vital factor affecting system cost and lifetime, energy consumption in wireless sensor networks (WSNs) has been paid much attention to. This article reviews existing energy harvesting technology applied in WSNs, and analyzes advantages of harvesting radio frequency (RF) energy in WSNs.

Time series analysis of lava flux

We have applied time series analytical techniques to the flux of lava from an extrusive eruption. Tilt data acting as a proxy for flux are used in a case study of the May–August 1997 period of the eruption at Soufrière Hills Volcano, Montserrat. We justify the use of such a proxy by simple calibratory arguments. Three techniques of time series analysis are employed: spectral, spectrogram and wavelet methods. In addition to the well-known ~9-hour periodicity shown by these data, a previously unknown periodic flux variability is revealed by the wavelet analysis as a 3-day cycle of frequency modulation during June–July 1997, though the physical mechanism responsible is not clear. Such time series analysis has potential for other lava flux proxies at other types of volcanoes.

How could construction supply chain benefit from RFID/GPS integration: a knowledge management perspective

Construction materials and equipment are essential building blocks of every construction project and may account for 50-60 per cent of the total cost of construction. The rate of their utilization, on the other hand, is the element that most directly relates to a project progress. A growing concern in the industry that inadequate efficiency hinders its success could thus be accommodated by turning construction into a logistic process. Although mostly limited, recent attempts and studies show that Radio Frequency IDentification (RFID) applications have significant potentials in construction. However, the aim of this research is to show that the technology itself should not only be used for automation and tracking to overcome the supply chain complexity but also as a tool to generate, record and exchange process-related knowledge among the supply chain stakeholders. This would enable all involved parties to identify and understand consequences of any forthcoming difficulties and react accordingly before they cause major disruptions in the construction process. In order to achieve this aim the study focuses on a number of methods. First of all it develops a generic understanding of how RFID technology has been used in logistic processes in industrial supply chain management. Secondly, it investigates recent applications of RFID as an information and communication technology support facility in construction logistics for the management of construction supply chain. Based on these the study develops an improved concept of a construction logistics architecture that explicitly relies on integrating RFID with the Global Positioning System (GPS). The developed conceptual model architecture shows that categorisation provided through RFID and traceability as a result of RFID/GPS integration could be used as a tool to identify, record and share potential problems and thus vastly improve knowledge management processes within the entire supply chain. The findings thus clearly show a need for future research in this area.

Pervasive technologies for workplace management

Purpose – Facilities managers have less visibility of how buildings are being used due to flexible working and unpredictable workers. The purpose of this paper is to examine the current issues in workspace management and an automatic solution through radio frequency identification (RFID) that could provide real time information on the volume and capacity of buildings. Design/methodology/approach – The study described in this paper is based on a case study at a facilities management (FM) department. The department is examining a ubiquitous technology in the form of innovative RFID for security and workspace management. Interviews and observations are conducted within the facilities department for the initial phase of the implementation of RFID technology. Findings – Research suggests that work methods are evolving and becoming more flexible. With this in mind, facilities managers face new challenges to create a suitable environment for an unpredictable workforce. RFID is one solution that could provide facilities managers with an automatic way of examining space in real time and over a wider area than currently possible. RFID alone for space management is financially expensive but by making the application multiple for other areas makes more business sense. Practical implications – This paper will provide practicing FM and academics with the knowledge gained from the application of RFID in this organisation. While the concept of flexible working seems attractive, there is an emerging need to provide various forms of spaces that enable employees' satisfaction and enhance the productivity of the organisation. Originality/value – The paper introduces new thinking on the subject of “workspace management”. It highlights the current difficulties in workspace management and how an RFID solution will benefit workspace methods.