Switches induced by quorum sensing in a model of enzyme-loaded microparticles

Quorum sensing refers to the ability of bacteria and other single-celled organisms to respond to changes in cell density or number with population-wide changes in behaviour. Here, simulations were performed to investigate quorum sensing in groups of diffusively coupled enzyme microparticles using a well-characterized autocatalytic reaction which raises the pH of the medium: hydrolysis of urea by urease. The enzyme urease is found in both plants and microorganisms, and has been widely exploited in engineering processes. We demonstrate how increases in group size can be used to achieve a sigmoidal switch in pH at high enzyme loading, oscillations in pH at intermediate enzyme loading and a bistable, hysteretic switch at low enzyme loading. Thus, quorum sensing can be exploited to obtain different types of response in the same system, depending on the enzyme concentration. The implications for microorganisms in colonies are discussed, and the results could help in the design of synthetic quorum sensing for biotechnology applications such as drug delivery

A NOVEL APPLICATION OF CHAOTIC PROPERTIES IN WATER TREATMENT PLANT

This paper aims at presenting a new optimization proposal to enhance the flocculation process in Water Treatment (WT) plant using a better flash mixing, located at KELAVERAPALLY, in Krishnagiri district, Tamil Nadu, India. Further, Sludge removal is done efficiently which decreases the water wastage as well as improvement in output water quality. Though WT plants are already equipped with systematic and sequential physicochemical processes, still they need to be optimized to obtain a better treated drinking water to maintain the quality standards as prescribed by World Health Organization. Chaotic behavior in chemical systems has been used to optimize the performance of WT plant. Measurement systems implemented in WT plant yield several chaotic based measurement parameters which are used to control the system operations to maintain the target water quality.  This intelligible data extraction through the proposed measurement  systems in a short span of time improves the plant performance without adding any costly systems except few changes in the existing plant setup.  Chaotic behavior is ensured through Lyapunov Exponents and Kolmogorov-Sinai Entropies. Both, water quality improvement and water wastage reduction is achieved simultaneously in the proposed work when a dosage prediction is done using Feed Forward Neural Networks. The treatment plant investigated has a maximum capacity of 14 MLD (Million litres per day) using two parallel streams with 7 MLD eac

A Framework for Life Cycle Cost Estimation of a Product Family at the Early Stage of Product Development

A cost estimation method is required to estimate the life cycle cost of a product family at the early stage of product development in order to evaluate the product family design. There are difficulties with existing cost estimation techniques in estimating the life cycle cost for a product family at the early stage of product development. This paper proposes a framework that combines a knowledge based system and an activity based costing techniques in estimating the life cycle cost of a product family at the early stage of product development. The inputs of the framework are the product family structure and its sub function. The output of the framework is the life cycle cost of a product family that consists of all costs at each product family level and the costs of each product life cycle stage. The proposed framework provides a life cycle cost estimation tool for a product family at the early stage of product development using high level information as its input. The framework makes it possible to estimate the life cycle cost of various product family that use any types of product structure. It provides detailed information related to the activity and resource costs of both parts and products that can assist the designer in analyzing the cost of the product family design. In addition, it can reduce the required amount of information and time to construct the cost estimation system

Evaluation of the colossal electroresistance (CER) effect and its application in the non-volatile Resistive Random Access Memory (RRAM)

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 79-81).Flash memory, the current leading technology for non-volatile memory (NVM), is projected by many to run obsolete in the face of future miniaturization trend in the semiconductor devices due to some of its technical limitations. Several different technologies have been developed in attempt for replacing Flash memory as the most dominant NVM technology; none of which seems to indicate significant success at the moment. Among these technologies is RRAM (Resistive Random Access Memory), a novel type of memory technology which has only recently emerged to join the race. The underlying principle of an RRAM device is based on the colossal electroresistance (CER) effect, i.e. the resistance switching behavior upon application of voltage of varying polarity and/or magnitude. This thesis aims to investigate the CER effect and how it can be designed to be a non-volatile memory as well as other novel application, e.g. memristor. The various technical aspects pertaining to this phenomenon, including the materials and the physical basis, are explored and analyzed. As a complementary to that, the market potential of the RRAM technology is also assessed. This includes the market study of memory industry, the current intellectual property (IP) landscape and some of the relevant business strategies. The production strategy (i.e. the production cost, initial investment, and pricing strategy) is then derived from the technical and market analysis evaluated earlier and with using some reasonable assumptions.by Aulia Tegar Wicaksono.M.Eng

Fabrication and characterization of memory devices based on nanoparticles

Tese de doutoramento, Engenharia Electrónica e Telecomunicações, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2013The objective of this study is to understand the electrical properties of non-volatile memories based on metal oxide nanoparticles embedded into an insulating polymer matrix. These memories are classified as resistive random access memories (RRAM), as they undergo resistive switching between well-defined conductance states when submitted to a voltage pulse. A number of memory devices were fabricated and studied using electrical techniques. Current-voltage characteristics were studied as a function of the ambient atmosphere and temperature. The dynamic electrical behaviour was probed using triangular voltage profiles with different scan rates, transient techniques and electrical noise techniques. Electrical measurements were complemented with morphological characterization. Important outcomes of this thesis are the following: It was shown that adsorbed moisture on the surface of the devices causes resistive switching. This type of resistive switching can lead to very high on/off ratios, and therefore it is not reliable. Silver oxide nanoparticles undergo an electroforming process similar to a soft-breakdown mechanism as reported for binary oxides. A model that explains the basic features of the electroforming mechanism was proposed. After the electroforming, the devices show resistance switching properties with a high on/off ratio (> 104), good retention time, and programming endurance. A resistive switching mechanism was proposed. The model assumes that during electroforming a percolation network of micro conducting paths (filaments) is established between the electrodes. The creation and rupture of these micro-paths is responsible for the changes in conductance. Results from this study indicate that nanostructured thin films made of silver oxide nanoparticles embedded in an insulating polymer show an electrical behaviour like the bulk oxide based memory structures. The planar structures present the advantage of being programmed in multi-resistance levels suggesting a very interesting finding that may pave the way to achieve a multi-bit memory deviceO objetivo desta tese foi estudar as propriedades elétricas de componentes electrónicos fabricados com nanopartículas de metálicas. Este tipo de memoria é designado por memorias resistivas porque mudam a sua resistência elétrica através da aplicação de um tensão elétrica. Este componente é conhecido por “memristor”. Um conjunto de memorias resistivas foi fabricado e caracterizado. Nomeadamente foram realizadas um conjunto de medidas elétricas em diferentes ambientes (vácuo e atmosfera ambiente) e em função da temperatura para obter informação sobre os mecanismos de transporte electrónico e sobre a comutação elétrica da resistência. As memorias fabricadas tem um elevado hiato entre os estados resistivos (> 104), são não-voláteis e robustas, tendo sido testadas com mais de mil ciclos de programação entre os estados resistivos. Esta tese propõe um modelo para explicar as variações de resistência elétrica. O modelo assume que as partículas de prata oxidam e formam um óxido de prata. Durante o processo de formação da memoria, o elevado campo elétrico aplicado leva a ruptura dielétrica controlada do óxido e forma defeitos eletricamente ativos. Esta rede de defeitos gera micro-caminhos para a condução elétrica ou filamentos. As mudanças de resistência elétrica são causadas pela criação/ruptura deste filamentos. Os resultados desta tese indicam que as mudanças de resistência elétrica em filmes nanoestruturados com nanopartículas metálicas são semelhantes as observadas em estruturas resistivas com base em filmes finos óxidos como o dióxido de titânio (TiO2) e o óxido de alumínio (Al2O3) entre outros. Os “memristors” fabricadas neste tese são estruturas planares. O objectivo inicial foi ter um instrumento de caracterização mais simples que a estrutura convencional em sanduiche. No entanto a estrutura planar permite também obter vários níveis de resistência elétrica sugerindo que pode funcionar como memorias “multi-bit”

Engineering for a Changing World: 59th IWK, Ilmenau Scientific Colloquium, Technische Universität Ilmenau, September 11-15, 2017 : programme

In 2017, the Ilmenau Scientific Colloquium is again organised by the Department of Mechanical Engineering. The title of this year’s conference “Engineering for a Changing World” refers to limited natural resources of our planet, to massive changes in cooperation between continents, countries, institutions and people – enabled by the increased implementation of information technology as the probably most dominant driver in many fields. The Colloquium, complemented by workshops, is characterised by the following topics, but not limited to them: – Precision Engineering and Metrology – Industry 4.0 and Digitalisation in Mechanical Engineering – Mechatronics, Biomechatronics and Mechanism Technology – Systems Technology – Innovative Metallic Materials The topics are oriented on key strategic aspects of research and teaching in Mechanical Engineering at our university

Mathematical model of interactions immune system with Micobacterium tuberculosis

Tuberculosis (TB) remains a public health problem in the world, because of the increasing prevalence and treatment outcomes are less satisfactory. About 3 million people die each year and an estimated one third of the world's population infected with Mycobacterium Tuberculosis (M.tb) is latent. This is apparently related to incomplete understanding of the immune system in infection M.tb. When this has been known that immune responses that play a role in controlling the development of M.tb is Macrophages, T Lymphocytes and Cytokines as mediators. However, how the interaction between the two populations and a variety of cytokines in suppressing the growth of Mycobacterium tuberculosis germ is still unclear. To be able to better understand the dynamics of infection with M tuberculosis host immune response is required of a model.One interesting study on the interaction of the immune system with M.tb mulalui mathematical model approach. Mathematical model is a good tool in understanding the dynamic behavior of a system. With the mediation of mathematical models are expected to know what variables are most responsible for suppressing the growth of Mycobacterium tuberculosis germ that can be a more appropriate approach to treatment and prevention target is to develop a vaccine. This research aims to create dynamic models of interaction between macrophages (Macrophages resting, macrophages activated and macrophages infected), T lymphocytes (CD4 + T cells and T cells CD8 +) and cytokine (IL-2, IL-4, IL-10,IL-12,IFN-dan TNF-) on TB infection in the lung. To see the changes in each variable used parameter values derived from experimental literature. With the understanding that the variable most responsible for defense against Mycobacterium tuberculosis germs, it can be used as the basis for the development of a vaccine or drug delivery targeted so hopefully will improve the management of patients with tuberculosis. Mathematical models used in building Ordinary Differential Equations (ODE) in the form of differential equation systems Non-linear first order, the equation contains the functions used in biological systems such as the Hill function, Monod function, Menten- Kinetic Function. To validate the system used 4th order Runge Kutta method with the help of software in making the program Matlab or Maple to view the behavior and the quantity of cells of each population

A Christian social ethic for Singapore with reference to the works of Ronald H. Preston

This thesis proposes a contextual Christian social ethic for a plural Singapore where Christianity, as a late arrival in East and Southeast Asia, is still regarded by most Asians as a foreign religion, mainly because of its association with past colonial exploits and present Euro-North American value-systems. Our thesis begins with an historical overview of Singapore from its founding as a British colony to its present position as an independent prosperous republic. Drawing on two failed attempts at Christian social engagement in post- colonial Singapore as examples, we argue against uncritical adoption of any social ethical model which is not culture-sensitive to the peculiar contextual concerns of that city-state. We show that an appropriate and credible Christian social ethic for Singapore can be found, not so much in Liberation Theologies or Ecclesiological Ethics, though they have rightly attracted a lot of attention in recent years, but rather in the social theology of Ronald. Preston and the tradition he represents. Preston's social theology, informed very much by a doctrine of creation, recognises God's grace at work in the life of all people and social structures. It encourages and facilitates constructive Christian social engagement in the political arena and the economic sphere where Christians, as members of overlapping communities, live and work with people of other faiths and those with no religious affiliation. When critically adapted and appropriately supplemented by other theological and philosophical materials in areas where we find deficiencies, Preston's social theology provides the congenial theological resources which can be used to frame a contextual Christian social ethic to meet the multi-faceted challenges of a plural, post-colonial Singapore