Electrospun Polyaniline-Reduced Graphene Oxide Composite Nanofibers Based High Sensitive Ammonia Gas Sensor

Ammonia is an important gas in many power plants and industrial processes so its detection is of extreme importance in environmental monitoring and process control due to its high toxicity. Ammonia���s threshold limit is 25 ppm and the exposure time limit is 8 h, however exposure to 35 ppm is only secure for 10 min. In this work a brief introduction to ammonia aspects are presented, like its physical and chemical properties, the dangers in its manipulation, its ways of production and its sources. The application areas in which ammonia gas detection is important and needed are also referred: environmental gas analysis (e.g. intense farming), automotive-, chemical- and medical industries. In order to monitor ammonia gas in these different areas there are some requirements that must be attended. These requirements determine the choice of sensor and, therefore, several types of sensors with different characteristics were developed, like metal oxides, surface acoustic wave-, catalytic-, and optical sensors, indirect gas analyzers, and conducting polymers. All the sensors types are described, but more attention will be given to polyaniline (PANI), particularly to its characteristics, syntheses, chemical doping processes, deposition methods, transduction modes, and its adhesion to inorganic materials. Besides this, short descriptions of PANI nanostructures, the use of electrospinning in the formation of nanofibers/microfibers, and graphene and its characteristics are included. The created sensor is an instrument that tries to achieve a goal of the medical community in the control of the breath���s ammonia levels being an easy and non-invasive method for diagnostic of kidney malfunction and/or gastric ulcers. For that the device should be capable to detect different levels of ammonia gas concentrations. So, in the present work an ammonia gas sensor was developed using a conductive polymer composite which was immobilized on a carbon transducer surface. The experiments were targeted to ammonia measurements at ppb level. Ammonia gas measurements were carried out in the concentration range from 1 ppb to 500 ppb. A commercial substrate was used; screen-printed carbon electrodes. After adequate surface pre-treatment of the substrate, its electrodes were covered by a nanofibrous polymeric composite. The conducting polyaniline doped with sulfuric acid (H2SO4) was blended with reduced graphene oxide (RGO) obtained by wet chemical synthesis. This composite formed the basis for the formation of nanofibers by electrospinning. Nanofibers will increase the sensitivity of the sensing material. The electrospun PANI-RGO fibers were placed on the substrate and then dried at ambient temperature. Amperometric measurements were performed at different ammonia gas concentrations (1 to 500 ppb). The I-V characteristics were registered and some interfering gases were studied (NO2, ethanol, and acetone). The gas samples were prepared in a custom setup and were diluted with dry nitrogen gas. Electrospun nanofibers of PANI-RGO composite demonstrated an enhancement in NH3 gas detection when comparing with only electrospun PANI nanofibers. Was visible higher range of resistance at concentrations from 1 to 500 ppb. It was also observed that the sensor had stable, reproducible and recoverable properties. Moreover, it had better response and recovery times. The new sensing material of the developed sensor demonstrated to be a good candidate for ammonia gas determination.

De touch: extending service channels in an airport through touch technologies

This project aimed to create a communication and interaction channel between Madeira Airport and its passengers. We used the pre-existent touch enabled screens at the terminal since their potential was not being utilised to their full capacity. To achieve our goal, we have followed an agile strategy to create a testable prototype and take advantages of its results. The developed prototype is based on a plugin architecture turning it into a maintainable and highly customisable system. The collected usage data suggests that we have achieved the initially defined goals. There is no doubt that this new interaction channel is an improvement regarding the provided services and, supported by the usage data, there is an opportunity to explore additional developments to the channel.

SIR performance evaluation of MB-OFDM UWB system with residual timing offset

Signal-to-interference ratio (SIR) performance of a multiband orthogonal frequency division multiplexing ultra-wideband system with residual timing offset is investigated. To do so, an exact mathematical derivation of the SIR of this system is derived. It becomes obvious that, unlike a cyclic prefixing based system, a zero padding based system is sensitive to residual timing offset.

A molecularly imprinted sensor for sensitive detection of 8-hydroxy-2'-deoxyguanosine (8-OHdG) oxidative stress biomarker

6th Graduate Student Symposium on Molecular Imprinting

New modified electrochemical conductive paper support for BSA detection

Chemical sensors and biosensors are widely used to detect various kinds of protein target biomolecules. Molecularly Imprinted Polymers (MIPs) have raised great interest in this area, because these act as antibody-like recognition materials, with high affinity to the template molecule. Compared to natural antibodies, these are also of lower cost and higher stability. There are different types of supports used to carry MIP materials, mostly of these made of gold, favourably assembled on a Screen Printed Electrode (SPE) strategy. For this work a new kind of support for the sensing layer was developed: conductive paper. This support was made by modifying first cellulose paper with paraffin wax (to make it waterproof), and casting a carbon-ink on it afterwards, to turn it conductive. The SPAM approach previously reported in1 was employed herein to assemble to MIP sensing material on the conductive paper. The selected charged monomers were (vinylbenzyl) trimethlammonium chloride (positive charge) or vinylbenzoic acid (negative charge), used to generate binding positions with single-type charge (positive or negative). The non-specific binding area of the MIP layer was assembled by chronoamperometry-assisted polymerization (at 1 V, for 60, 120 or 180 seconds) of vinylbenzoate, cross-linked with ethylene glycol vinyl ether. The BSA biomolecules lying within the polymeric matrix were removed by Proteinase K action. All preparation stages of the MIP assembly were followed by FTIR, Raman spectroscopy and, electrochemical analysis. In general, the best results were obtained for longer polymerization times and positively charged binding sites (which was consistent with a negatively-charged protein under physiological pH, as BSA). Linear responses against BSA concentration ranged from 0.005 to 100 mg/mL, in PBS buffer standard solutions. The sensor was further calibrated in standard solutions that were prepared in synthetic or real urine, and the analytical response became more sensitive and stable. Compared to the literature, the detection capability of the developed device is better than most of the reported electrodes. Overall, the simplicity, low cost and good analytical performance of the BSA SPE device, prepared with positively charged binding positions, seems a suitable approach for practical application in clinical context. Further studies with real samples are required, as well as gathering with electronic-supporting devices to allow on-site readings.

Performance Model for MRC Receivers with Adaptive Modulation and Coding in Rayleigh Fading Correlated Channels with Imperfect CSIT

RTUWO Advances in Wireless and Optical Communications 2015 (RTUWO 2015). 5-6 Nov Riga, Latvia.

Cation transporters/channels in plants: Tools for nutrient biofortification

Cation transporters/channels are key players in a wide range of physiological functions in plants, including cell signaling, osmoregulation, plant nutrition and metal tolerance. The recent identification of genes encoding some of these transport systems has allowed new studies toward further understanding of their integrated roles in plant. This review summarizes recent discoveries regarding the function and regulation of the multiple systems involved in cation transport in plant cells. The role of membrane transport in the uptake, distribution and accumulation of cations in plant tissues, cell types and subcellular compartments is described. We also discuss how the knowledge of inter- and intra-species variation in cation uptake, transport and accumulation as well as the molecular mechanisms responsible for these processes can be used to increase nutrient phytoavailability and nutrients accumulation in the edible tissues of plants. The main trends for future research in the field of biofortification are proposed.

Calcium signaling and the novel anti-proliferative effect of the UTP-sensitive P2Y11 receptor in rat cardiac myofibroblasts

During myocardial ischemia and reperfusion both purines and pyrimidines are released into the extracellular milieu, thus creating a signaling wave that propagates to neighboring cells via membrane-bound P2 purinoceptors activation. Cardiac fibroblasts (CF) are important players in heart remodeling, electrophysiological changes and hemodynamic alterations following myocardial infarction. Here, we investigated the role UTP on calcium signaling and proliferation of CF cultured from ventricles of adult rats. Co-expression of discoidin domain receptor 2 and -smooth muscle actin indicate that cultured CF are activated myofibroblasts. Intracellular calcium ([Ca2+]i) signals were monitored in cells loaded with Fluo-4 NW. CF proliferation was evaluated by the MTT assay. UTP and the selective P2Y4 agonist, MRS4062, caused a fast desensitizing [Ca2+]i rise originated from thapsigargin-sensitive internal stores, which partially declined to a plateau providing the existence of Ca2+ in the extracellular fluid. The biphasic [Ca2+]i response to UTP was attenuated respectively by P2Y4 blockers, like reactive blue-2 and suramin, and by the P2Y11 antagonist, NF340. UTP and the P2Y2 receptor agonist MRS2768 increased, whereas the selective P2Y11 agonist NF546 decreased, CF growth; MRS4062 was ineffective. Blockage of the P2Y11receptor or its coupling to adenylate cyclase boosted UTP-induced CF proliferation. Confocal microscopy and Western blot analysis confirmed the presence of P2Y2, P2Y4 and P2Y11 receptors. Data indicate that besides P2Y4 and P2Y2 receptors which are responsible for UTP-induced [Ca2+]i transients and growth of CF, respectively, synchronous activation of the previously unrecognized P2Y11 receptor may represent an important target for anti-fibrotic intervention in cardiac remodeling.

Achieving K/DOQI Targets with Cinacalcet in Dialysis Patients with Secondary Hyperparathyroidism. A Portuguese Observational Study

Secondary hyperparathyroidism is a common complication of chronic kidney disease. The elevated serum intact parathyroid hormone, phosphorus, calcium and calcium x phosphorus product have been independently associated with an increased relative risk of mortality. The standard therapy for secondary hyperparathyroidism, including active vitamin D analogues and phosphate binders, is often insufficient to allow patients to achieve the recommended Kidney Disease Outcomes Quality Initiative targets for bone and mineral metabolism. Randomised controlled phase III clinical studies in chronic kidney disease patients with secondary hyperparathyroidism have shown that cinacalcet treatment increases the proportion of patients achieving the recommended Kidney Disease Outcomes Quality Initiative targets for intact parathyroid hormone, phosphorus, calcium and calcium x phosphorus product. Aims: This observational multicentre study aims to evaluate cinacalcet���s ability to achieve and maintain Kidney Disease Outcomes Quality Initiative targets in a population with secondary hyperparathyroidism on chronic haemodialysis in Portugal. Patients and Methods: Patients on chronic dialysis that received cinacalcet during a free sampling programme were enrolled. Retrospective and prospective monthly data were collected from 3 months before until 6 months after the beginning of cinacalcet treatment. Additional assessment included a 12 month evaluation of all parameters. Results: 140 dialysis patients with secondary hyperparathyroidism were enrolled, 60% male, mean age 57.4��14.1 years. The mean intact parathyroid hormone, calcium, phosphorus, and calcium x phosphorus product values at baseline were 751.7��498.8 pg/ml, 9.7��3.8 mg/dl, 5.5��1.5 mg/dl, and 52.7��25.3 mg2/dl2, respectively. After 6 months��� cinacalcet treatment, 26.2%, 53.6%, 59.3%, and 81.0% of the patients achieved the Kidney Disease Outcomes Quality Initiative recommended levels for intact parathyroid hormone, calcium, phosphorus, and calcium x phosphorus product, respectively. The mean dose of cinacalcet at 6 months was 57.1��29.7 mg/day. Conclusions: The use of cinacalcet in clinical practice is an effective option for the treatment of secondary hyperparathyroidism in chronic dialysis patients, allowing more patients to reach and maintain the Kidney Disease Outcomes Quality Initiative targets.

Novos circuitos regulat��rios de controlo espacio-temporal do desenvolvimento em bacillus subtilis

RESUMO: A esporula����o em Bacillus subtilis �� controlada por uma cascata de factores sigma da polimerase do RNA. ���F e ���E controlam os est��gios precoces do desenvolvimento no pr��-esporo e na c��lula m��e, respectivamente. Numa fase interm��dia da diferencia����o, quando a c��lula m��e acaba por envolver o pr��-esporo, ���F �� substitu��do por ���G e ���E �� substitu��do por ���K. V��rios mecanismos asseguram que a actividade dos diferentes factores sigma seja confinada a uma janela temporal precisa na c��lula adequada. Neste estudo, investig��mos a fun����o de um factor anti-���G, designado por CsfB. Mostramos que para al��m da sua fun����o de inibi����o da actividade do factor ���G em c��lulas pr��-divisionais, CsfB �� tamb��m necess��rio na c��lula m��e num est��gio tardio do desenvolvimento. Mostramos que a express��o de csfB �� activada na c��lula m��e a partir de um promotor dependente de ���K. Contudo, demonstramos que CsfB interage directamente com ���E e n��o com ���K, e que CsfB �� suficiente para inibir a actividade transcricional dependente de ���E em c��lulas vegetativas de B. subtilis. Propomos que CsfB contribui para reduzir o per��odo dependente de ���E, na linha de express��o gen��tica da c��lula m��e, desse modo reduzindo a sobreposi����o entre os regul��es ���E e ���K e aumentado a fidelidade do processo de desenvolvimento. Uma segunda prote��na, YabK, partilha semelhan��a estrutural com CsfB. YabK �� produzida no pr��-esporo sob o comando de ���F, e �� necess��ria para a esporula����o. YabK contribui para a transi����o ���F/���G no programa gen��tico do pr��-esporo, porque uma muta����o que torna ���F sens��vel a CsfB ultrapassa parcialmente a fun����o de YabK na esporula����o. No entanto, YabK e CsfB funcionam por mecanismos diferentes, uma vez que YabK n��o liga directamente a ���F.---------ABSTRACT: Gene expression during spore development in Bacillus subtilis is governed by a cascade of RNA polymerase sigma factors. ���F and ���E control the early stages of development in the forespore and in the mother cell, respectively. At an intermediate stage in the differentiation process, when the larger mother cell finishes engulfment of the smaller forespore, ���F is replaced by ���G and ���E is replaced by ���K. Several mechanisms ensure the proper timing of activation of the cell type-specific sigma factors. Here, we have investigated the funtion of an anti-sigma ���G factor, called CsfB. We show here that in addition to its role in inhibiting ���G in pre-divisional cells, CsfB is also required in the mother cell at a late stage in development. We show that the expression of csfB is activated in the mother cell from a ���K-specific promoter. However, we demonstrate that CsfB binds directly to ���E but not to ���K in a yeast two-hybrid assay, and that CsfB is sufficient to inhibit ���E-dependent transcriptional activity in vegetative cells of B. subtilis. We posit that CsfB contributes to shutting off the early, ���E-controlled period in the mother cell line of gene expression, thus reducing the overlap between deployment of the ���E and ���K regulons and increasing the fidelity of the developmental process. A second protein, YabK, shares structural similarity with CsfB. YabK is produced in the forespore under ���F control, and is required for efficient sporulation. YabK contributes to the transition from the ���F- to the ���G-dependent period of gene expression, because a mutation that renders ���F sensitive to CsfB partially bypasses the need for YabK. Yet, YabK and CsfB must function in the control of sigma factor activity by different mechanisms because YabK does not bind directly to ���F.

Stochastic simulation of the morphology of fluvial sand channels reservoirs

Disserta����o para obten����o do Grau de Mestre em Engenharia Geol��gica (Georrecursos)

Ligand K-edge X-ray absorption spectroscopy and DFT calculations on [Fe3S4]0,+ clusters: delocalization, redox, and effect of the protein environment

Ligand K-edge XAS of an [Fe3S4]0 model complex is reported. The pre-edge can be resolved into contributions from the ��2Ssulfide, ��3Ssulfide, and Sthiolate ligands. The average ligand-metal bond covalencies obtained from these pre-edges are further distributed between Fe3+ and Fe2.5+ components using DFT calculations. The bridging ligand covalency in the [Fe2S2]+ subsite of the [Fe3S4]0 cluster is found to be significantly lower than its value in a reduced [Fe2S2] cluster (38% vs 61%, respectively). This lowered bridging ligand covalency reduces the superexchange coupling parameter J relative to its value in a reduced [Fe2S2]+ site (-146 cm-1 vs -360 cm-1, respectively). This decrease in J, along with estimates of the double exchange parameter B and vibronic coupling parameter ��2/k-, leads to an S ) 2 delocalized ground state in the [Fe3S4]0 cluster. The S K-edge XAS of the protein ferredoxin II (Fd II) from the D. gigas active site shows a decrease in covalency compared to the model complex, in the same oxidation state, which correlates with the number of H-bonding interactions to specific sulfur ligands present in the active site. The changes in ligand-metal bond covalencies upon redox compared with DFT calculations indicate that the redox reaction involves a two-electron change (one-electron ionization plus a spin change of a second electron) with significant electronic relaxation. The presence of the redox inactive Fe3+ center is found to decrease the barrier of the redox process in the [Fe3S4] cluster due to its strong antiferromagnetic coupling with the redox active Fe2S2 subsite.

HIGH SENSITIVE PCR METHOD FOR DETECTION OF PATHOGENIC Leptospira spp. IN PARAFFIN-EMBEDDED TISSUES

This study describes the development and application of a new PCR assay for the specific detection of pathogenic leptospires and its comparison with a previously reported PCR protocol. New primers were designed for PCR optimization and evaluation in artificially-infected paraffin-embedded tissues. PCR was then applied to post-mortem, paraffin-embedded samples, followed by amplicon sequencing. The PCR was more efficient than the reported protocol, allowing the amplification of expected DNA fragment from the artificially infected samples and from 44% of the post-mortem samples. The sequences of PCR amplicons from different patients showed >99% homology with pathogenic leptospires DNA sequences. The applicability of a highly sensitive and specific tool to screen histological specimens for the detection of pathogenic Leptospira spp. would facilitate a better assessment of the prevalence and epidemiology of leptospirosis, which constitutes a health problem in many countries.

Estudo de vulnerabilidades em aplica����es web e o seu reflexo em dom��nios Portugueses

Muito se tem falado sobre revolu����o tecnol��gica e do aparecimento constante de novas aplica����es Web, com novas funcionalidades que visam facilitar o trabalho dos utilizadores. Mas ser�� que estas aplica����es garantem que os dados transmitidos s��o tratados e enviados por canais seguros (protocolos)? Que garantias �� que o utilizador tem que mesmo que a aplica����o utilize um canal, que prev�� a privacidade e integridade de dados, esta n��o apresente alguma vulnerabilidade pondo em causa a informa����o sens��vel do utilizador? Software que n��o foi devidamente testado, aliado �� falta de sensibiliza����o por parte dos respons��veis pelo desenvolvimento de software para quest��es de seguran��a, levam ao aumento de vulnerabilidades e assim exponenciam o n��mero de potenciais v��timas. Isto aliado ao efeito de desinibi����o que o sentimento de invisibilidade pode provocar, conduz ao facilitismo e consequentemente ao aumento do n��mero de v��timas alvos de ataques inform��ticos. O utilizador, por vezes, n��o sabe muito bem do que se deve proteger, pois a confian��a que dep��em no software n��o pressup��em que os seus dados estejam em risco. Neste contexto foram recolhidos dados hist��ricos relativos a vulnerabilidades nos protocolos SSL/TLS, para perceber o impacto que as mesmas apresentam e avaliar o grau de risco. Para al��m disso, foram avaliados um n��mero significativo de dom��nios portugueses para perceber se os mesmos t��m uma vulnerabilidade espec��fica do protocolo SSL/TLS.