In this study, two different flow field plates, a serpentine field plate and a perforated filed plate, were produced by LIGA-like formation and micro electroforming technology. The two type field plates were also used to make up three different types of micro proton exchange membrane fuel cells (µPEMFCs), serpentine (anode)-serpentine (cathode), serpentine-perforated, and perforated-perforated, each of whose active area is 1 cm2. In addition to the performance tests under different flow rate, operation temperature, and relative humidity conditions, electrochemical impedance spectroscopy (EIS) and cyclic votammetry (CV) methods were also adapted to measure correspondent EIS and Pt utilization of MEA. Even the fuel cell with serpentine field plates in anode and cathode needs more pressure input, the extra pressure is effective to avoid the water accumulation and to raise the total performance.

The eis gene of M. tuberculosis is believed to play a role in the intracellular survival of this pathogen. Significantly higher levels of antibodies to Eis were detected by ELISA in the sera of patients with tuberculosis as compared to healthy controls. PBMCs from recovered TB donors were also found to demonstrate significantly higher levels of proliferation in response to stimulation with the Eis protein than PBMCs from either active TB cases or healthy controls. Neither the active TB population nor the healthy controls showed significant levels of IFN- or IL-4 secretion in response to stimulation of PBMC with Eis or ESAT-6. Far Western analysis determined that Eis interacts with a ~65 kDa protein that localizes to the cytoplasmic fraction of M. tuberculosis lysate. Real-time PCR analysis of M. tuberculosis infected U-937 macrophages showed that the eis gene is constitutively expressed during infection. Using immunofluorescence microscopy (IF), the Eis protein was detected within the cytoplasm of M. tuberculosis infected macrophages indicating that the protein was being released/secreted from the mycobacterium containing phagosomes. Western blot analysis of the cytoplasm of macrophages infected with M. tuberculosis expressing green fluorescent protein confirmed these results. Western blot analysis also detected the presence of native Eis both in the culture supernatant of infected macrophages and vesicles released from the macrophages. IF also detected the presence of Eis in uninfected macrophages. The Eis protein in the cytoplasm of M. tuberculosis infected macrophages was also found to colocalize with EEA1, an endosomal marker, indicating a possible association of the protein with early endosomes. Eis was also shown to elicit higher levels of IL-10 secretion than PPD in human monocytes. Infection of monocytes from healthy tuberculin reactors with M. tuberculosis wild type and eis mutant demonstrated that eis plays a role in modulation of IL-10/TNF- secretion in response to infection. Bioinformatic analysis of the amino acid sequence of Eis indicates that Eis is an acetyltransferase of the GCN5 related family of N-acetyltransferases. Further work is required to determine the role Eis plays in the survival of M. tuberculosis within the macrophage.

The aim of present work was to study corrosion properties of magnetron sputtered Mg–Al alloys and characterize semiconductor properties of the surface layers developed during corrosion. Atomic force microscopy (AFM) demonstrated that sputtered alloys had a smaller grain size and a smoother surface. Corrosion and electrochemical behaviour of the alloys was studied in 0,1M (NH4)3BO3 + 0,1M NaCl (pH = 8,4) solution. Sputtered films of Al-Mg and Al had a superior resistance to pitting corrosion when compared to cast counterparts. The corrosion resistance of sputtered samples increased with decrease in Mg content. The Mott – Schottky plots of Al-Mg and pure Al electrodes showed a linear relationship between modified capacitance (C-2) on applied potential. It was concluded n – type semiconductivity for the layers on Al and p – type for Al-Mg alloys.

abstract: Biosensors offer excellent diagnostic methods through precise quantification of bodily fluid biomarkers and could fill an important niche in diagnostic screening. The long term goal of this research is the development of an impedance immunosensor for easy-to-use, rapid, sensitive and selective simultaneously multiplexed quantification of bodily fluid disease biomarkers. To test the hypothesis that various cytokines induce empirically determinable response frequencies when captured by printed circuit board (PCB) impedance immunosensor surface, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods were used to test PCB biosensors versus multiple cytokine biomarkers to determine limits of detection, background interaction and response at all sweep frequencies. Results indicated that sensors for cytokine Interleukin-12 (IL-12) detected their target over three decades of concentration and were tolerant to high levels of background protein. Further, the hypothesis that cytokine analytes may be rapidly detected via constant frequency impedance immunosensing without sacrificing undue sensitivity, CV, EIS, impedance-time (Zt) methods and modeling were used to test CHITM gold electrodes versus IL-12 over different lengths of time to determine limits of detection, detection time, frequency of response and consistent cross-platform sensor performance. Modeling and Zt studies indicate interrogation of the electrode with optimum frequency could be used for detection of different target concentrations within 90 seconds of sensor exposure and that interrogating the immunosensor with fixed, optimum frequency could be used for sensing target antigen. This informs usability of fixed-frequency impedance methods for biosensor research and particularly for clinical biosensor use. Finally, a multiplexing impedance immunosensor prototype for quantification of biomarkers in various body fluids was designed for increased automation of sample handling and testing. This enables variability due to exogenous factors and increased rapidity of assay with eased sensor fabrication. Methods were provided for simultaneous multiplexing through multisine perturbation of a sensor, and subsequent data processing. This demonstrated ways to observe multiple types of antibody-antigen affinity binding events in real time, reducing the number of sensors and target sample used in the detection and quantification of multiple biomarkers. These features would also improve the suitability of the sensor for clinical multiplex detection of disease biomarkers. / Dissertation/Thesis / Ph.D. Bioengineering 2012

Although investment in IT is growing rapidly, a number of studies have shown that the full benefits of this technology are not realised. One explanation is that these benefits exist, but have not been correctly measured. The other explanation is that they have not been achieved because of lack of management attention. Experience and common sense supports the latter assumption. Hence, the aim of this research is to develop and to trial a method which assists in the realisation of the benefits of a particularly problematic technology, executive information systems (EIS).The proposed method introduces the concept of generic benefits models into previous research on IT benefits management. This construct improves existing methods of benefits management in three respects. First, it employs reuse of benefits models in order to speed their development. Secondly, it allows these methods to be employed at any stage of a project, not just at the outset, in order to extract benefits. Thirdly, it provides a conceptual object which serves as the focus of organisational learning. The major focus of the research is on the development of generic benefits models of EIS. This requires an understanding of the role which information plays in executive work and how EIS technology may affect the manner in which executives use information. Unfortunately, the literature on executive work does not make this clear. Moreover, it seems that there is no agreed definition of EIS. As a result, it is necessary to create different generic models for different theories of executive work and different forms of EIS. The methodological approach adopted is pragmatism, in particular the experimentalism proposed by John Dewey and implemented by Donald Schon. The justification for this is that the primary objective of the study is to demonstrate the utility of the proposed method rather than its ability to explain, predict, or provide insight. The study includes six experiments conducted within the office of the Malaysian Prime Minister. Different types of EIS, with different degrees of benefits already realised, and at different stages of development are the subjects of these experiments. The results largely affirm the proposed method, but they do suggest some refinement of the original benefits models. They also indicate simplification of the models is possible. In addition the executives who participated in these experiments favour the proposed method. However, the IS practitioners in the organisation are less enthusiastic. The study proposes a solution to this problem which includes both changes to organisational structure and to the education of IS practitioners. The research also produced a number of supplementary findings. It reaffirmed the findings of Mintzberg's study of executive work. It demonstrated once again that executives rarely use EIS directly and that they mostly depended on subordinates to access information. When executives do employ EIS themselves, they are more likely to use it to enhance their learning than to support decision-making.

Nickel-Yttria Stabilized Zirconia (Ni-YSZ) cermets are used as anodes in solid oxide fuel cells. These anodes are stable for tens of thousands of hours during operation and have low cost. In this work, Ni-YSZ anodes are infiltrated with nickel nanoparticles to increase the density of electrochemical reaction sites and improve their performance. However, infiltrated nickel nanoparticles are isolated from one another, so they are not electrochemically active. Two approaches have been utilized to activate infiltrated nickel nanoparticles: in-situ nickel spreading and simultaneous infiltration of nickel with Gd0.1Ce0.9O2-δ (GDC). In-situ nickel spreading, which occurs during exposure to anodic mass transfer limited currents, connects and activates nickel nanoparticles, improving anode performance but inherently causing nanoparticle coarsening. Simultaneous infiltration of Ni and GDC results in substantially improved anode performance, and the infiltrated nanostructures are more stable than infiltrated nickel. Detailed analysis of the electrochemical impedance by equivalent circuit modeling is used to separate the contributions of nickel and GDC infiltrants to the overall cell performance.

El problema de investigación que sustenta esta tesis por compendio de publicaciones gravita en la idea de que el influjo del enfoque tecnocrático y positivista dominante en el ejercicio de las EIA y EIS actuales – y que la perspectiva constructivista no ha logrado resolver-, provoca una serie de profundas carencias en la gestión social de las intervenciones planificadas como planteamiento. A partir del establecimiento de las dificultades subyacentes al enfoque tecnocrático como problema de investigación, esta subyacentes al enfoque tecnocrático como problema de investigación, esta tesis trata de afrontar desde la reflexividad sociológica los siguientes objetivos: 1.-Realizar un análisis crítico de la aproximación a la dimensión social del enfoque dominante de las EIS y EIA de las intervenciones sobre el medio desde una perspectiva paradigmática (axiología, ontología, epistemología y metodología). Concretamente aspira a: 2.- Establecer un diagnóstico de las consecuencias que posee la realización de los procesos de evaluación de las intervenciones desde el enfoque tecnocrático y positivista en relación con el tratamiento a través del análisis crítico de la aproximación a la dimensión social realizada desde el enfoque tecnocrático de la evaluación de impacto. 3.-Resolver las limitaciones detectadas mediante el desarrollo de propuestas teórico-conceptuales y metodológicas en el marco de varios casos de estudio. Específicamente pretender ahondar en las causas profundas generadoras de la desigual distribución de los riesgos e impactos entre los grupos humanos afectados a través de la introducción sistemática del enfoque de la vulnerabilidad social EIS. Asimismo, la introducción de este enfoque perseguirá proporcionar elementos conceptuales y metodológicos que faciliten la integración de la dialéctica entre procesos estructurales y capacidad de agencia en el análisis de impacto. Articular una propuesta metodológica que permita el análisis de las complejas relaciones de casualidad e interdependencias entre las redes sociales, económicas y ambientales desde el enfoque holístico y sistémico. Desarrollar, desde el marco de la transdisciplinariedad, una propuesta metodológica que posibilite la adecuada integración de la dimensión social de los procesos de evaluación.

No description available.

No description available.

O biodiesel (BD) tem sido peça chave para redução das emissões de gases de efeito estufa em diversos países em virtude da sua compatibilidade com motores de ciclodiesel automotivos ou estacionários. Contudo, por ser um meio orgânico e altamente resistivo, o uso de técnicas eletroquímicas para estudar sua corrosividade frente a metais é bastante desafiador. No presente trabalho, foi estudada a corrosividade do BD através do uso de microeletrodos (MES) de níquel, alumínio e cobre, o potencial desempenho de amidas graxas na redução da corrosividade desse meio e, ainda, a viabilidade do uso da técnica Scanning Vibrating Electrode Technique (SVET). Para tal, foram obtidos e caracterizados por voltametria cíclica staircase (VCS) MEs de 25 µm de diâmetro de platina, cobre, níquel e alumínio. Com exceção do ME de Pt, todos os MEs foram caracterizados em meios em que são ativos, sendo os resultados obtidos para os MEs de Ni e de Al não encontrados em buscas nas bases de dados da literatura. Foram realizados ensaios gravimétricos para o Ni, Al e para o Cu em BD, sendo o último utilizado também para o estudo das amidas graxas 1-(1-pirrolidinil)-1-octadecanona e N-[2-hidroxi-1,1-bis(hidroximetil)etil]stearamida como inibidores de corrosão. Foram feitas medidas de espectroscopia de impedância eletroquímica (EIE) com todos os MEs em BD bom (BDB) e degradado (BDDE), sendo também inéditos os resultados referentes aos MEs de Ni e de Al nesses meios. Nos ensaios com SVET foram avaliados, imersos em BDB e BDDE, os pares galvânicos Cu/Zn e Cu/Ni, com e sem polarização potenciostática e, ainda, o cobre puro. Os resultados de VCS evidenciaram que a técnica utilizada para obtenção dos MEs foi exitosa. Os ensaios gravimétricos evidenciaram que a corrosão é maior para o Cu, seguida do Al e do Ni. Ainda, estes ensaios evidenciaram que nenhuma das amidas testadas foi capaz de inibir a corrosão do Cu. Para os MEs de Al e Cu, nos espectros de EIE obtidos em BDB foi possível identificar a presença de duas constantes de tempo (CT), enquanto no BDDE as duas CT foram identificadas para todos os MEs. A primeira CT foi associada a uma resposta conjunta da capacitância do BD e da difusão frente à geometria do ME, sendo a segunda CT associada a resposta da dupla camada. A técnica SVET demonstrou que corrosão ao Zn do par Zn/Cu é maior do que frente a do Ni no par Cu/Ni, conforme esperado. Os resultados mostram a viabilidade de uso da técnica de SVET para avaliar o comportamento de metais em BD. / Biodiesel has been a key to reduce greenhouse gas emissions in several countries because of its compatibility with automotive or stationary cycle motors. However, because it is an organic and highly resistive medium, the use of electrochemical techniques to study its corrosiveness toward metals is quite challenging. In the present work, biodiesel\'s corrosiveness was studied with nickel, aluminum and copper MEs by Electrochemical Impedance Spectroscopy (EIS). Furthermore, it was studied the potential performance of fatty amides as corrosion inhibitor for copper, and the feasibility of using Scanning Vibrating Electrode Technique (SVET) in studies with biodiesel. Therefore, platinum, copper, nickel and aluminum ME\'s (Æ=µm) were obtained and characterized by staircase cyclic voltammetry (VCS). Gravimetric tests were run for nickel, aluminum and copper in pure biodiesel. For biodiesel doped with 1- (1-pyrrolidinyl) -1-octadecanone and N- [2-hydroxy-1,1- bis (hydroxymethyl) ethyl] stearamide, the gravimetric tests were restricted to copper. EIS tests were carried out with all MEs on good (GB) and degraded (DB) biodiesel. From our best knowledge, it is the first time that nickel and aluminum MEs are being reported in studies with biodiesel. For SVET experiments, it was used Cu, Cu/Zn and Cu/Ni samples. The VCS results showed that the technique used to obtain the MEs was successful. The gravimetric tests showed that the biodiesel corrosiveness is higher for copper, followed by aluminum and nickel. Further, these tests showed that none of the amides were able to inhibit copper corrosion in biodiesel. For Cu and Al MEs in GB, the EIS spectra showed two-time constants (TC), while in DB the second TC could be seen for all MEs. The first TC was associated to biodiesel\'s capacitance and a ME\'s geometry response, while the second TC was related to double layer response. Also, from the fitting of the data to an equivalent electric circuit it was possible to determine the charge transfer resistance for each of the systems that showed two TCs. The SVET results showed that the corrosion of Zn in Zn / Cu pair is higher than that of Ni in the Cu / Ni pair, as expected. This fact proved that the SVET is feasible to study the corrosion behavior of metals in biodiesel.