Enhanced zinc oxide and graphene nanostructures for electronics and sensing applications

Zinc oxide and graphene nanostructures are important technological materials because of their unique properties and potential applications in future generation of electronic and sensing devices. This dissertation investigates a brief account of the strategies to grow zinc oxide nanostructures (thin film and nanowire) and graphene, and their applications as enhanced field effect transistors, chemical sensors and transparent flexible electrodes. Nanostructured zinc oxide (ZnO) and low-gallium doped zinc oxide (GZO) thin films were synthesized by a magnetron sputtering process. Zinc oxide nanowires (ZNWs) were grown by a chemical vapor deposition method. Field effect transistors (FETs) of ZnO and GZO thin films and ZNWs were fabricated by standard photo and electron beam lithography processes. Electrical characteristics of these devices were investigated by nondestructive surface cleaning, ultraviolet irradiation treatment at high temperature and under vacuum. GZO thin film transistors showed a mobility of ∼5.7 cm2/V·s at low operation voltage of <5 V and a low turn-on voltage of ∼0.5 V with a sub threshold swing of ∼85 mV/decade. Bottom gated FET fabricated from ZNWs exhibit a very high on-to-off ratio (∼106) and mobility (∼28 cm2/V·s). A bottom gated FET showed large hysteresis of ∼5.0 to 8.0 V which was significantly reduced to ∼1.0 V by the surface treatment process. The results demonstrate charge transport in ZnO nanostructures strongly depends on its surface environmental conditions and can be explained by formation of depletion layer at the surface by various surface states. A nitric oxide (NO) gas sensor using single ZNW, functionalized with Cr nanoparticles was developed. The sensor exhibited average sensitivity of ∼46% and a minimum detection limit of ∼1.5 ppm for NO gas. The sensor also is selective towards NO gas as demonstrated by a cross sensitivity test with N2, CO and CO2 gases. Graphene film on copper foil was synthesized by chemical vapor deposition method. A hot press lamination process was developed for transferring graphene film to flexible polymer substrate. The graphene/polymer film exhibited a high quality, flexible transparent conductive structure with unique electrical-mechanical properties; ∼88.80% light transmittance and ∼1.1742Ω/sq k sheet resistance. The application of a graphene/polymer film as a flexible and transparent electrode for field emission displays was demonstrated.

Investigation of generation -recombination noise and related processes in aluminum gallium arsenide TEGFETs and Hall structures with quantum wells

Experimental and theoretical studies regarding noise processes in various kinds of AlGaAs/GaAs heterostructures with a quantum well are reported. The measurement processes, involving a Fast Fourier Transform and analog wave analyzer in the frequency range from 10 Hz to 1 MHz, a computerized data storage and processing system, and cryostat in the temperature range from 78 K to 300 K are described in detail. The current noise spectra are obtained with the “three-point method”, using a Quan-Tech and avalanche noise source for calibration. ^ The properties of both GaAs and AlGaAs materials and field effect transistors, based on the two-dimensional electron gas in the interface quantum well, are discussed. Extensive measurements are performed in three types of heterostructures, viz., Hall structures with a large spacer layer, modulation-doped non-gated FETs, and more standard gated FETs; all structures are grown by MBE techniques. ^ The Hall structures show Lorentzian generation-recombination noise spectra with near temperature independent relaxation times. This noise is attributed to g-r processes in the 2D electron gas. For the TEGFET structures, we observe several Lorentzian g-r noise components which have strongly temperature dependent relaxation times. This noise is attributed to trapping processes in the doped AlGaAs layer. The trap level energies are determined from an Arrhenius plot of log (τT2) versus 1/T as well as from the plateau values. The theory to interpret these measurements and to extract the defect level data is reviewed and further developed. Good agreement with the data is found for all reported devices. ^

Recanto do vale do pium: condomínio de habitações com ênfase no baixo impacto ambiental e no desempenho térmico do ambiente construído

This work describes the design process of a small recreational gated community in Pium, Nísia Floresta/RN, from concept to final design stages, with emphasis on low environmental impact, thermal comfort and the spatial quality of housing. The process consisted in a review of the literature and relevant standards, studies of design references and architectural programming. The project development was initially focused on the project’s feasibility, with the definition of the number of units, implantation, size and location of the dwellings and the common areas of the development. Two types of houses (four low rise and five duplex units) have been proposed in order to attend the premises of architectural programming. The conception of the architectural design began with the rooms’ zoning according to the lots. This resulted in the pre-selection of three alternatives that were evaluated in terms of spatial quality and environmental performance. The development of sketches focused on the envelope consistent with the bioclimatic guidelines and on the language of the compatible proposal with the lowest possible environmental impact of the building system, which resulted in the selection of the eucalyptus wood type. During the working drawings, the Quality Technical Regulation for the Level of Energy Efficiency Residential Buildings (RTQ -R) was adopted for the evaluation of the envelope, which resulted in "B" level of efficiency for the first case. After minor adjustments, mainly in frames, the efficiency level rose to "A", demonstrating that early project decisions contributed to the envelope energy performance. Besides the design of the two types of units, the final proposal of the gated community includes the design of the equipment for the common areas (entrance, multipurpose room and support and service sector), and the descriptive texts explaining the project and construction’s details.

Sobre formas e processos: projeto de um condomínio de casas a partir de princípios da gramática da forma

With the intention of studying and developing the design process based on a specific methodology, the object of this work is to present the design of a gated condominium community in Natal based on the application of principles of shape grammar, used in their design process. The shape grammar is a design method developed in the 1970s by George Stiny and James Gips. It is used for the analysis of the project as well as for its synthesis, with the goal of creating a "formal vocabulary" through mathematical and/or geometrical operations. Here, the methodology was used in the synthesis of the design process, through the relationship between formal subtractions and the houses’ architectural planning. As a result, five dwellings configurations were proposed, each one different from the other with respect to their shape and architectural programming, distributed in three twin groups, which are repeated until the final total of nine architectural volumes. In addition to studies of the condominium’s ventilation and the buildings’ shading simulations, studies of spatial flexibility and acoustic performance were also performed. The mapping of the design process, one of the specific objectives of the dissertation, was composed not only by the record of formal constraints (the preparation and application of rules), but also by physical, environmental, legal and sustainability aspects in relation to, on one hand, the optimization of the shading and passive ventilation for hot and humid climates, and, on the other hand, the modulation and rationalization of the construction.

Direct In Vivo Manipulation and Imaging of Calcium Transients in Neutrophils Identify a Critical Role for Leading-Edge Calcium Flux.

Calcium signaling has long been associated with key events of immunity, including chemotaxis, phagocytosis, and activation. However, imaging and manipulation of calcium flux in motile immune cells in live animals remain challenging. Using light-sheet microscopy for in vivo calcium imaging in zebrafish, we observe characteristic patterns of calcium flux triggered by distinct events, including phagocytosis of pathogenic bacteria and migration of neutrophils toward inflammatory stimuli. In contrast to findings from ex vivo studies, we observe enriched calcium influx at the leading edge of migrating neutrophils. To directly manipulate calcium dynamics in vivo, we have developed transgenic lines with cell-specific expression of the mammalian TRPV1 channel, enabling ligand-gated, reversible, and spatiotemporal control of calcium influx. We find that controlled calcium influx can function to help define the neutrophil's leading edge. Cell-specific TRPV1 expression may have broad utility for precise control of calcium dynamics in other immune cell types and organisms.

Synthesis of a PbTx-2 photoaffinity and fluorescent probe and an alternative synthetic route to photoaffinity probes

A natural phenomenon characterized by dense aggregations of unicellular photosynthetic marine organisms has been termed colloquially as red tides because of the vivid discoloration of the water. The dinoflagellate Karenia brevis is the cause of the Florida red tide bloom. K. brevis produces the brevetoxins, a potent suite of neurotoxins responsible for substantial amounts of marine mammal and fish mortalities. When consumed by humans, the toxin causes Neurotoxic Shellfish Poisoning (NSP). The native function of brevetoxin within the organism has remained mysterious since its discovery. There is a need to identify factors which contribute to and regulate toxin production within K. brevis. These toxins are produced and retained within the cell implicating a significant cellular role for their presence. Localization of brevetoxin and identification of a native receptor may provide insight into its native role as well as other polyether ladder type toxins such as the ciguatoxins, maitotoxins, and yessotoxins. In higher organisms these polyether ladder molecules bind to transmembrane proteins with high affinity. We anticipated the native brevetoxin receptor would also be a transmembrane protein. Photoaffinity labeling has become increasingly popular for identifying ligand receptors. By attaching ligands to these photophors, one is able to activate the molecule after the ligand binds to its receptor to obtain a permanent linkage between the two. Subsequent purification provides the protein with the ligand directly attached. A molecule that is capable of fluorescence is a fluorophore, which upon excitation is capable of re-emitting light. Fluorescent labeling uses fluorophores by attaching them covalently to biologically active compounds. The synthesis of a brevetoxin photoaffinity probe and its application in identifying a native brevetoxin receptor will be described. The preparation of a fluorescent derivative of brevetoxin will be described and its use in localizing the toxin to an organelle within K. brevis. In addition, the general utility of a synthesized photoaffinity label with other toxins having similar functionality will be described. An alternative synthetic approach to a general photoaffinity label will also be discussed whose goal was to accelerate the preparation and improve the overall synthetic yields of a multifunctional label.

Seawater carbonate chemistry and Strongylocentrotus purpuratus body length and gene expression pattern changes during experiments, 2011

Extensive use of fossil fuels is leading to increasing CO2 concentrations in the atmosphere and causes changes in the carbonate chemistry of the oceans which represents a major sink for anthropogenic CO2. As a result, the oceans' surface pH is expected to decrease by ca. 0.4 units by the year 2100, a major change with potentially negative consequences for some marine species. Because of their carbonate skeleton, sea urchins and their larval stages are regarded as likely to be one of the more sensitive taxa. In order to investigate sensitivity of pre-feeding (2 days post-fertilization) and feeding (4 and 7 days post-fertilization) pluteus larvae, we raised Strongylocentrotus purpuratus embryos in control (pH 8.1 and pCO2 41 Pa e.g. 399 µatm) and CO2 acidified seawater with pH of 7.7 (pCO2 134 Pa e.g. 1318 µatm) and investigated growth, calcification and survival. At three time points (day 2, day 4 and day 7 post-fertilization), we measured the expression of 26 representative genes important for metabolism, calcification and ion regulation using RT-qPCR. After one week of development, we observed a significant difference in growth. Maximum differences in size were detected at day 4 (ca. 10 % reduction in body length). A comparison of gene expression patterns using PCA and ANOSIM clearly distinguished between the different age groups (Two way ANOSIM: Global R = 1) while acidification effects were less pronounced (Global R = 0.518). Significant differences in gene expression patterns (ANOSIM R = 0.938, SIMPER: 4.3% difference) were also detected at day 4 leading to the hypothesis that differences between CO2 treatments could reflect patterns of expression seen in control experiments of a younger larva and thus a developmental artifact rather than a direct CO2 effect. We found an up regulation of metabolic genes (between 10 to 20% in ATP-synthase, citrate synthase, pyruvate kinase and thiolase at day 4) and down regulation of calcification related genes (between 23 and 36% in msp130, SM30B, SM50 at day 4). Ion regulation was mainly impacted by up regulation of Na+/K+-ATPase at day 4 (15%) and down regulation of NHE3 at day 4 (45%). We conclude that in studies in which a stressor induces an alteration in the speed of development, it is crucial to employ experimental designs with a high time resolution in order to correct for developmental artifacts. This helps prevent misinterpretation of stressor effects on organism physiology.

#DressCodePM & Re-Framing The Niqab: News Sources, Hashtag Activism, and Media Representation

This thesis originates from my interest in exploring how minorities are using social media to talk back to mainstream media. This study examines whether hashtags that trend on Twitter may impact how news stories related to minorities are covered in Canadian media. The Canadian Prime Minister Stephen Harper stated the niqab was “rooted in a culture that is anti-women” on 10 March 2015. The next day #DressCodePM trended in response to the PM’s niqab remarks. Using network gatekeeping theory, this study examines the types of sources quoted in the media stories published on 10 and 11 March 2015. The study’s goal is to explore whether using tweet quotes leads to the representation of a more diverse range of news sources. The study compares the types of sources quoted in stories that covered Harper’s comments without mentioning #DressCodePM versus stories that mention #DressCodePM. This study also uses Tuen A. van Dijk’s methodology of asking “who is speaking, how often and how prominently?” in order to examine whose voices have been privileged and whose voices have been marginalized in covering the niqab in Canadian media from the 1970s and until the days following the PM’s remarks. Network gatekeeping theory is applied in this study to assess whether the gated gained more power after #DressCodePM trended. The case study’s findings indicates that Caucasian male politicians were predominantly used as news sources in covering stories related to the niqab for the past 38 years in the Globe and Mail. The sourcing pattern of favouring politicians continued in Canadian print and online media on 10 March 2015 following Harper’s niqab comments. However, ordinary Canadian women, including Muslim women, were used more often than politicians as news sources in the stories about #DressCodePM that were published on 11 March 2015. The gated media users were able to gain power and attract Canadian Media’s attention by widely spreading #DressCodePM. This study draws attention to the lack of diversity of sources used in Canadian political news stories, yet this study also shows it is possible for the gated media users to amplify their voices through hashtag activism.

β-Arrestin-mediated Regulation of the Human Ether-a-go-go-Related Gene (hERG) Potassium Channel

The human ether-a-go-go-related gene (hERG) encodes the voltage-gated K+ channel, hERG (Kv11.1). This channel passes the rapidly-activating delayed rectifier K+ current (IKr), which is important for cardiac repolarization. A reduction in IKr due to loss-of-function mutations or drug interactions causes long QT syndrome (LQTS), which can lead to cardiac arrhythmias and sudden cardiac death. The density of hERG channels in the plasma membrane is a key determinant of normal physiological function, and is balanced by trafficking to and from the cell surface. Many LQTS-associated hERG mutations result in a trafficking deficiency of otherwise functional channels. Thus, elucidating mechanisms of hERG regulation at the plasma membrane is useful for the prevention and treatment of LQTS. We previously demonstrated that M3 muscarinic receptor activation increases mature hERG expression through a Gq protein-dependent protein kinase C (PKC) pathway. In addition to conventional Gq protein-coupling, M3 receptors recruit β-arrestins upon agonist binding. Traditionally known for their role in receptor desensitization and internalization, β-arrestins also act as adaptor proteins to facilitate G protein-independent signaling. In the present work, I investigated the exclusive effect of β-arrestin signaling on hERG expression by utilizing an arrestin-biased M3 designer receptor (M3D-arr) exclusively activated by clozapine-N-oxide (CNO). By expressing M3D-arr in hERG-HEK cells and treating with CNO under various conditions, I found that M3D-arr activation increased mature hERG expression and current. Within this paradigm, M3D-arr recruited β-arrestin to the plasma membrane, and promoted the PI3K-dependent activation of Akt. I further found that the activated Akt acted through phosphatidylinositol 3-phosphate 5-kinase (PIKfyve) and Rab11 to facilitate endosomal recycling of hERG channels to the plasma membrane.

CaV channels and cancer: canonical functions indicate benefits of repurposed drugs as cancer therapeutics

The importance of ion channels in the hallmarks of many cancers is increasingly recognised. This article reviews current knowledge of the expression of members of the voltage-gated calcium channel family (CaV) in cancer at the gene and protein level and discusses their potential functional roles. The ten members of the CaV channel family are classified according to expression of their pore-forming α-subunit; moreover, co-expression of accessory α2δ, β and γ confers a spectrum of biophysical characteristics including voltage dependence of activation and inactivation, current amplitude and activation/inactivation kinetics. CaV channels have traditionally been studied in excitable cells including neurones, smooth muscle, skeletal muscle and cardiac cells, and drugs targeting the channels are used in the treatment of hypertension and epilepsy. There is emerging evidence that several CaV channels are differentially expressed in cancer cells compared to their normal counterparts. Interestingly, a number of CaV channels also have non-canonical functions and are involved in transcriptional regulation of the expression of other proteins including potassium channels. Pharmacological studies show that CaV canonical function contributes to the fundamental biology of proliferation, cell-cycle progression and apoptosis. This raises the intriguing possibility that calcium channel blockers, approved for the treatment of other conditions, could be repurposed to treat particular cancers. Further research will reveal the full extent of both the canonical and non-canonical functions of CaV channels in cancer and whether calcium channel blockers are beneficial in cancer treatment.

Quantum-limited estimation of continuous spontaneous localization

We apply the formalism of quantum estimation theory to extract information about potential collapse mechanisms of the continuous spontaneous localisation (CSL) form.
In order to estimate the strength with which the field responsible for the CSL mechanism couples to massive systems, we consider the optomechanical interaction
between a mechanical resonator and a cavity field. Our estimation strategy passes through the probing of either the state of the oscillator or that of the electromagnetic field that drives its motion. In particular, we concentrate on all-optical measurements, such as homodyne and heterodyne measurements.
We also compare the performances of such strategies with those of a spin-assisted optomechanical system, where the estimation of the CSL parameter is performed
through time-gated spin-like measurements.

A implementação de ações de integração na segurança pública: o caso das polícias civil e militar do Rio Grande do Norte

The research aimed to understand the challenges for the implementation of the proposed integration between the Civil Police and the Military Police in Rio Grande do Norte to the proposals of the SUSP. This study aimed to explore the gap with regard to the deepening of the possible causes that may hinder the implementation of integrated working between the police in public security, through a specific analysis on the state of Rio Grande do Norte. Was based on a theoretical framework that includes policies: general concepts, the steps of a public policy, the implementation stage , public security : conceptual definitions, policies on security in Brazil, the structure of public security in Brazil and systems police, Military Police x Civil Police: Roles and conflicts , integrating public security: the challenges to be overcome, the Unified public Safety (SUSP) and the main difficulties in the integration of the police. Being classified as to the purposes as an exploratory research on how to approach ranks as qualitative. The research unit was the Center for Integrated Operations Public Safety (CIOSP) through three subjects who were the chief CIOSP, the representative of the military police acting with the CIOSP, and representative civil police also active with the CIOSP. These subjects were chosen because of the understanding that individuals occupying senior positions would have more ability to respond to questions that guide the research problem. Data were collected through a set of interviews, qualitative data analysis was performed based content analysis, based on the definition of categories of analysis, gated time cross. With the results, it was revealed that the main problems of integration between the state police are treatment protocols, lack of political will and lack of infrastructure. The relationship between the Military Police and Civil Police in Rio Grande do Norte has differing cultural aspect, but can be considered as good value, professionalism and integrated operations. The implementation of CIOSP-RN followed the characteristics of the top-down model, the main difficulties in implementing the proposals of the SUSP, lack of own resources, the lack of standardization in public safety and the lack of professional training of public safety. It was concluded that with respect to the challenges to the implementation of the proposed integration between the Civil Police and the Military Police in Rio Grande do Norte to the proposals of the SUSP, the actions follow the characteristics of the top-down model, with no autonomy of administrators public to say in decisions, which restricts the view of the public safety of the state

Estudo numérico do escoamento em descarregadores por orifício

Atualmente, no estudo do comportamento de descarregadores de cheias por orifício, é necessário conhecer as pressões ao longo do descarregador, para várias alturas de água na albufeira. Este tipo de estudos tem sido usualmente realizado recorrendo a ensaios experimentais. No entanto, a utilização de modelos numéricos para a simulação do escoamento em estruturas hidráulicas encontra-se numa fase emergente. Neste sentido, a presente dissertação pretende apresentar um estudo numérico relativo ao escoamento em descarregadores de cheias por orifício. Por forma a efetuar o estudo numérico, foi utlizado o programa comercial de CFD FLOW-3D®, reproduzindo um modelo reduzido construído no Laboratório Nacional de Engenharia Civil (LNEC) correspondente a um descarregador por orifício. Para a realização das simulações numéricas foi necessário definir o objeto de estudo, a malha de cálculo, as condições de fronteira e as propriedades do fluido e objeto de modo a reproduzir as situações ensaiadas experimentalmente no LNEC. A proximidade dos resultados experimentais e numéricos para vários níveis de água na albufeira permitiu validar o modelo numérico para este tipo de escoamentos no interior do orifício.

Condomínios fechados: a produção habitacional contemporânea e a auto-exclusão dos ricos no espaço urbano de Natal RN (1995 2003)

The present work analyzes the fast evolution of gated communities in Natal-RN´s urban space. Characterized by the occupation of large areas, providing private security and utilities, this kind of real estate use arises a long list of questions and issues from society and scholars, due to privatization of urban space, bending of law constraints and the lack of an integrated planning of the cities where they are built. The reasons for its fast growth in Brazil s urban areas are analyzed, considering the impact on formal urban planning and municipal services and on the identification of urbanistic, architectural pattern and constraints, as well as legal, social and economic issues. This study is based on the detailed analysis of the first three units of gated communities built in the urban space in Natal, between 1995 and 2003, including their evolution throughout time and the specific social and economic reasons for its present widespread adoption in Brazilian real estate market and, particulary, in our city. The main objective of this piece of work is to answer the why s and how s these phenomena evolved, setting a basis for the definition of adequate public policies and regulation of this kind of urban land use