982 resultados para SENSITIVE K CHANNEL
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In this brief, a read-only-memoryless structure for binary-to-residue number system (RNS) conversion modulo {2(n) +/- k} is proposed. This structure is based only on adders and constant multipliers. This brief is motivated by the existing {2(n) +/- k} binary-to-RNS converters, which are particular inefficient for larger values of n. The experimental results obtained for 4n and 8n bits of dynamic range suggest that the proposed conversion structures are able to significantly improve the forward conversion efficiency, with an AT metric improvement above 100%, regarding the related state of the art. Delay improvements of 2.17 times with only 5% area increase can be achieved if a proper selection of the {2(n) +/- k} moduli is performed.
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A bi-enzymatic biosensor (LACCTYRAuNPsCS/GPE) for carbamates was prepared in a single step by electrodeposition of a hybrid film onto a graphene doped carbon paste electrode (GPE). Graphene and the gold nanoparticles (AuNPs) were morphologically characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, dynamic light scattering and laser Doppler velocimetry. The electrodeposited hybrid film was composed of laccase (LACC), tyrosinase (TYR) and AuNPs entrapped in a chitosan (CS) polymeric matrix. Experimental parameters, namely graphene redox state, AuNPs:CS ratio, enzymes concentration, pH and inhibition time were evaluated. LACCTYRAuNPsCS/GPE exhibited an improved MichaelisMenten kinetic constant (26.9 0.5 M) when compared with LACCAuNPsCS/GPE (37.8 0.2 M) and TYRAuNPsCS/GPE (52.3 0.4 M). Using 4-aminophenol as substrate at pH 5.5, the device presented wide linear ranges, low detection limits (1.6810 9 1.1810 10 2.1510 7 3.4110 9 M), high accuracy, sensitivity (1.13106 8.11104 2.19108 2.51107 %inhibition M 1), repeatability (1.25.8% RSD), reproducibility (3.26.5% RSD) and stability (ca. twenty days) to determine carbaryl, formetanate hydrochloride, propoxur and ziram in citrus fruits based on their inhibitory capacity on the polyphenoloxidases activity. Recoveries at two fortified levels ranged from 93.8 0.3% (lemon) to 97.8 0.3% (orange). Glucose, citric acid and ascorbic acid do not interfere significantly in the electroanalysis. The proposed electroanalytical procedure can be a promising tool for food safety control.
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1st European IAHR Congress, 6-4 May, Edinburgh, Scotland
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River Flow 2008, Vol.1
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This paper studies the effect of ship speed and water depth on the propagation of ship generated waves. The ship is represented by a moving pressure distribution function at the free surface that is able to reproduce most of the phenomena involved in wave propagation. Results are obtained for a ship sailing along a coastal stretch made of a sloping bottom and a constant depth region. The results show that in the sloping bottom the crests of waves are bent along the slope and in the constant depth the standard Kelvin wave patterns can be found for the subcritical regime. In the critical regime the wave system is characterized by significant diverging waves and for a supercritical regime, the transverse waves disappear. 2015 Taylor & Francis Group, London.
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As quinoxalinas so compostos heterocclicos que tm, entre outras, capacidades antimicrobianas, inclusivamente contra bactrias resistentes aos antimicrobianos convencionais. Os mecanismos pelos quais estes compostos exercem a sua atividade ainda no est completamente esclarecido. O objetivo do presente estudo avaliar o efeito redox em sinergismo/antagonismo com as quinoxalinas em modelos de bactrias com e sem resistncias a antimicrobianos. No que se refere aos compostos foram utilizados a quinoxalina 1,4-dixido (QNX), 2-metil-3-benzilquinoxalina-1,4-dixido (2M3BQNX), 2-metilquinoxalina-1,4-dixido (2MQNX) e a 2-amino-3-cianoquinoxalina-1,4-dixido (2A3CQNX). Quanto aos modelos procariotas, foram utilizados a Salmonella enterica, Klebsiella pneumoniae, Enterococcus faecalis, Staphylococcus saprophyticus, Enterobacter aerogenes, Enterobacter cloacae, Staphylococcus aureus ATCC 25923, Methicillin-resistant Staphylococcus aureus ATCC 43300, Escherichia coli TEM 201 e Escherichia coli TEM 180. Nos compostos qumicos em que se verificou a Concentrao Mnima Inibitria (CMI), realizou-se o estudo do comportamento do crescimento bacteriano. Relativamente ao estado redox, foi avaliado para cada estirpe sensvel, atravs do rcio GSH/GSSG, nas doses inibitrias e no inibitrias de cada composto. Os resultados apresentam que todos os compostos testados, exceo do 2M3BQNX, tm atividade antimicrobiana na maioria das estirpes, excetuando a E. faecalis e a S. saprophyticus. Os rcios GSH/GSSG apontam para o efeito oxidante em K. pneumoniae e S. enterica e antioxidante na E. aerogenes. A concluso do estudo sugere que os compostos apresentam elevada capacidade antibacteriana e influncia no equilbrio redox das bactrias, podendo contribuir para o esclarecimento do mecanismo de ao dos derivados das quinoxalinas 1-4 dixido, nas bactrias.
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RESMO: Introduo: A anemia de clulas falciformes doena hereditria, com repercusso multi-orgnica, tem grande variabilidade na sua expresso clnica. Da o interesse do estudo de indicadores de prognstico. A investigao realizada foi precedida de um resumo histrico incidindo sobre a compreenso de aspectos fundamentais da doena ao longo dos tempos. Na primeira parte do estudo e aps reviso bibliogrfica, foram referidos dados da fisiopatologia como base para os estudos que integram a presente dissertao. Abordou-se o estado da arte relativamente s complicaes, aos indicadores de prognstico e teraputica utilizada. Objectivos: Constituram objectivos deste estudo realizado numa amostra populacional representativa: identificar as leses a nvel dos sistemas cardio-respiratrio e nervoso central, avaliando-se as respectivas repercusses; avaliar a presena de indicadores de prognstico entre as variveis seleccionadas; estudar a eficcia e toxicidade da HU nos doentes com as formas graves da ACF. Para a prossecuo destes objectivos foram delineados para alm do estudo global trs estudos especficos: Estudo 1- repercusso no sistema cardio-respiratrio; Estudo 2- repercusso no sistema nervoso central; Estudo 3- teraputica com hidroxiureia. Doentes e mtodos: Procedeu-se a um estudo prospectivo e multi-institucional durante um perodo de trs anos tendo-se seleccionado para a amostra, e de acordo com critrios pr-definidos, 30 doentes com ACF na fase estvel da doena, com idades compreendidas entre os sete e os 18 anos, todos de origem africana excepo de um caucasiano. O diagnstico baseou-se em tcnicas de electroforese e estudo molecular que definiu o genotipo da doena e a presena da deleco da -talassmia assim como os haplotipos da amostra populacional. Foram utilizadas diferentes metodologias para avaliar a existncia de leso pulmonar e cerebral. Atravs do estudo estatstico foram seleccionadas diversas variveis como hipotticos indicadores de prognstico. Estudo 1. Para determinar a existncia de leso a nvel pulmonar usaram-se duas metodologias diferentes, a avaliao da funo pulmonar com estudo da saturao da Hb em O2 no sangue arterial e a tomografia computadorizada de alta resoluo. Estudou-se tambm a possvel disfuno cardaca como repercusso da leso pulmonar, atravs do ecocardiograma, e os indicadores de prognstico com significado estatstico para a leso encontrada. Estudo 2. O desenho deste estudo foi sobreponvel ao anterior, mas com metodologia adequada para o SNC. Procedeu-se ao estudo das leses cerebrais por meio de exames imagiolgicos, (RMN-CE e DTC) e de testes psicolgicos. Correlacionaram-se as trs metodologias utilizadas e a importncia de cada uma para a deciso de atitudes teraputicas preventivas. Estudo 3. Consistiu num estudo aberto prospectivo no controlado com nove crianas e adolescentes com formas graves de ACF, com o objectivo de avaliar a eficcia da teraputica com hidroxiureia, durante um perodo de 24 meses. Todos os doentes completaram no mnimo 15 meses de teraputica, com uma dose final mdia de 194 mg/K/dia. Resultados globais: Durante o perodo anterior investigao caracterizou-se a amostra populacional estudada quanto ao fenotipo gentico, clnico e hematolgico de acordo com os critrios utilizados por outros investigadores. Verificou-se: predomnio do haplotipo Bantu na forma homozigtica em 53% dos doentes; nmero total de EVO 3/ano em 87,5% dos doentes; crises de sequestrao em 18,75%; dactilites no primeiro ano de vida em 31,2%; quadro de spsis grave apenas num doente; crises de hiper-hemlise em 50%; e STA em 59,38% dos doentes. Quanto ao fenotipo hematolgico evidenciaram-se como factores de risco reticulocitose (13,1x103/l) e hiperbilirrubinmia (2,5 mg/dl) e como factores de bom prognstico a presena de deleco de um gene da -talassmia em 46,9% dos doentes e valor mdio de Hb 8,1 g/dl. Resultados dos estudos parcelares: Estudo 1. Deste estudo infere-se que a DPR ligeira foi diagnosticada em 70% dos doentes, uma vez que as alteraes da difuso no foram estatisticamente significativas, o estudo dos gases no sangue no evidenciaram resultados anormais e a TCAR evidenciou alteraes em 43,3% dos doentes. Apenas num doente se verificou doena pulmonar obstrutiva relacionada com maior nmero da STA.O estudo da disfuno cardaca encontrada em 86,7% dos doentes no reflecte a repercusso da DPR a nvel cardaco, podendo estar associada s alteraes fisiopatolgicas da prpria anemia crnica. Encontraram-se indicadores de prognstico hematolgicos e clnicos. Entre os primeiros, valores de Hb 8,5 g/dl e de HbF 13% foram considerados indicadores de bom prognstico para a leso pulmonar. Em relao aos parmetros clnicos, as STA no foram consideradas indicadoras de prognstico para a DPR ao contrrio do que se verificou com o nmero de EVO. Pela anlise dos parmetros genticos e socio-econmicos provou-se a ausncia de relao estatisticamente significativa com leso pulmonar. Estudo 2. Pela RMN-CE foram diagnosticados ES em 33,3% com uma localizao preferencial na substncia branca profunda em 26,6% dos doentes. Relativamente aos parmetros hematolgicos seleccionados, o valor mdio da HbF 8,6% constituu um indicador de bom prognstico para o aparecimento de ES, enquanto o valor mdio de leuccitos 12.39x103/l foi considerado um indicador de mau prognstico. No estudo do DTC apenas um doente apresentou aumento da velocidade do fluxo cerebral na ACM igual a 196 cm/segundos, associado a vasculopatia grave. Os testes psicolgicos alterados em 80% dos doentes mostraram ser o mtodo mais sensvel para detectar alteraes do neurodesenvolvimento, mas sem correlao com os ES em 10% dos doentes. Reala-se a baixa percentagem de DTC patolgicos encontrados neste estudo em relao ao nmero elevado de ES e de testes psicolgicos alterados, no se verificando concordncia entre os trs exames. Dos indicadores de prognstico estudados a -talassmia foi considerada um factor de proteco para o coeficiente de inteligncia da escala de Wechsler. Em relao a parmetros clnicos estudados os doentes com maior nmero de EVO, tem em mdia valores inferiores nos testes psicolgicos. Estudo 3. Neste estudo verificou-se que o valor mdio da HbF aumentou significativamente de 7,04% para 13,75,3% (p=0,028) ao fim de 15 meses de teraputica com hidroxiureia. Clinicamente todos os doentes responderam significativamente com uma reduo de 80% no nmero de EVO, 69% no nmero de internamentos, 76% no nmero de dias de hospitalizao e 67% no nmero de transfuses. Deste modo comprovou-se no s a eficcia desta teraputica neste grupo peditrico como tambm a falta de efeitos secundrios significativos. Considera-se a necessidade de estudos mais prolongados e em grande sries, para com segurana se usar a HU antes que a leso orgnica se estabelea, portanto logo nos primeiros anos de vida. Concluso: Na amostra populacional estudada foram evidenciadas leses pulmonares e cerebrais na grande maioria dos doentes que condicionaram a sua qualidade de vida. Foram identificados indicadores de prognstico que podero eventualmente ditar medidas teraputicas precoces com o objectivo de diminuir a morbilidade e a mortalidade neste grupo etrio. Demonstrou-se que a teraputica com a HU foi eficaz e bem tolerada----------ABSTRACT: Background: Sickle cell anemia (SCA), a hereditary disease characterized by pain and lifetime multi-organic lesion, is a challenge for all that work with carriers of this disease. The clinical expression variability of SCA is a constant reality and a problem to be solved in the current world of investigation, for which the knowledge of prognostic indicators responsible for the different aspects of clinical evolution diversity wiil be an added value. The study is preceded by a historical summary of the most important factors in the evolution of SCA, which are in themselves, an incentive for future research. In the first part of the study, after an extensive bibliographical revision, physiopathology data is referred to in general and specifically regarding the target organs, that constituted the base for the studies presented in the dissertation. The state of the art for the complications to be studied, the choice of prognostic indicators and the therapeutics application, were approached for the renewed interest in the theme. Aims: In regard to the investigation, the objective was to study the lesions in the most affected organs of a chosen pediatric group, to investigate prognostic indicators for lung and cerebral lesions and to evaluate the protective effect of hydroxyurea in children with severe outcomes. Patients and methods: A prospective and multi-institutional study was carried out during a three-year period, February 1998 to March 2001, with children and adolescents followed up at a Immunohematology Outpatient Clinic of Dona Estefnia's Hospital, Lisbon. Based in predefined criteria, 30 children with SCA were selected in a stable phase of the disease, aged from seven to 18 years old, all of whom were of African origin with exception of one who was Caucasian. The diagnosis was based on electrophoresis techniques and molecular study that allowed to define the genotype, the presence of deletional alpha-thalassemia as well as haplotypes in the population. Different methodologies were used to evaluate the existence of lung and cerebral lesion. Statistical study of the different variables selected the prognostic indicators. In Study 1, to determine the existence of lung lesion two different methodologies were used: pulmonar function study with arterial blood gases determination; and high resolution computerized tomography. Heart dysfunction as a repercussion of lung lesion was also studied through echocardiography, and prognostic indicators were statistically significant for lesions found. The design of Study 2 was similar to Study 1, but with the appropriate methodology for CNS. After neurological examination, which was normal in all patients (control group), cerebral lesions were studied with imagiologic exams (MRN-CE and TCD) and psychological tests. These three methodologies were correlated and the importance of each one in the decision of the therapeutic profilactic attitudes. Study 3 consisted of a controlled prospective open study in children with severe forms of SCA, with the aim of the evaluating therapeutic effectiveness of hydroxyurea, during a period of 24 months. Results: In the global overall study preceding the Studies 1,2 and 3, there were a prevalence of haplotype Bantu (53%) and other risk factors, namely the number of VOC (87,5%), sequestration crisis (18,75%), dactilytis in first year of life(31,2%), hyperhemolysis crisis (50%) and ATC in more than half of the patients (59,38%). This group of bad prognostic indicators, associated with the population of the lower class according to the Graffar scale, demonstrates the importance of primary health care services, information provided to the children and their relatives, as well as the interest in prophylactic therapeutics, specific screening and prenatal diagnosis. Study 1. It was evident from this study that slight RPD was diagnosed in 70% of the patients, because alterations of the diffusion had no statistical significance and arterial blood gases determinations were normal. Only one patient had restrictive lung disease related with numerous ACS. However ACS was not considered a prognostic indicator for RPD, contrary to the number of EVO. HRTC revealed discreet fibrotic lines that could be related with slight RPD, but the lack of correlation of these two exams (33%) supports the value of lung function tests for precocious diagnosis of RPD. Heart dysfunction was found in 86,7% of patients, does not reflect the repercussion of RPD, but with the physiopathology of chronic anemia. Hematologic and clinical prognostic indicators were found. Good prognostic indicators for the non-evolution of RPD with average Hb values of 8,5 g/dl and average HbF values of 13%, respectively. The genetic and social-economic factors had no statistical significance; nevertheless, they were more prevalent among Bantu haplotype (53,3%) in patients with RPD. Study 2. RMN-CE detected SI in 33,3% of the patients, with preferential location in deep white substance in 26,6% and in front lobe in 20%. This distribution can be related to structural aspects of the brain and with the high sensibility of this organ to hypoxia. From the hematological parameters selected, average HbF value 8,6% and average leucocyte count 12.39x103/l were prognostic indicators with different meaning to SI. The increase in the total bilirubin related to hyperhemolysis clinically explains the genesis of SI In the TCD study, only one patient had increased cerebral flow speed >196 cm/sec in CMA, which corresponded to serious vasculopathy in AngioMR. This patient never present previously neurological symptoms and had several hyperhemolysis crisis and VOC as risk factors. Low percentage of pathological TCD in this study, in relation to the high number of SI and altered tests, although without correlation among the three exams, is probably attributed to factors related to the methodology, aspects of cerebral physiopathology or perhaps a sign of good prognostic if the duration of study had not been so short. TCD should be used as a screening method in the age groups with higher risk of AVC and should never be considered separately in prophylactic therapeutics indication. Psychological tests were the most sensitive method to detect neurodevelopment impairment; in 80% of patients the neuropsychologics tests were altered, but without correlation with SI (10%). Since SI can become evident during the first two years of life and develop with time, the first psychological tests should be carried out between 3 and 5 years of age to timely be referred to special education and stimulation programs. Prognostic indicators to psychological tests were also found: alpha-thalassemia was found to be a protection factor of the IQ, just as other hematologic factors (hematocrit, MGCV and erythrocytes count). In relation to clinical parameters, although without statistical significance, patients with larger number of VOC had average lower scores versus the average in tests, except in TP. Results from different studies were conclusive as to the type of lesion found and the importance of prognostic indicators. Study 3. All the patients completed a minimum of 15 months therapeutic treatment with the final average daily dose of 194 mg/kg/day. The average value of the fetal hemoglobin increased significantly from 7,03,9% to 13,75,3% (p=0.028). The HbF average values increased from 6% to 15% after 15 months of therapeutic treatment. Clinically there was a reduction of 80% in the number of VOE , 69% in the number of hospitalization, 76% in the number of days of hospitalization and 67% in the number of transfusions. Once again the effectiveness of this treatment in this pediatric group, as well as the lack of any significant secondary effects, was evident. The study confirms the need for further detailed research in order to safely effect the appropriate treatment prior to the development of organic lesions, which ideally should be in the first year of life. Conclusions: These results allow us to clarify the importance of either pulmonary lesions or either nervous central system impairment among patients, children and adolescents, with sickle cell anemia. These lesions were demonstrated in most of the patients studied compromising their quality of life and the mortality. The treatment with HU is proved to be effective and having low toxicity.
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Dissertao para obteno do grau de Doutor em Cincias da Comunicao Especialidade de Comunicao e Cultura
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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. Ammonias 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 breaths 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.
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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.
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International Conference on Emerging Technologies and Factory Automation (ETFA 2015), Industrial Communication Technologies and Systems, Luxembourg, Luxembourg.
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8th International Workshop on Multiple Access Communications (MACOM2015), Helsinki, Finland.
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6th Graduate Student Symposium on Molecular Imprinting
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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.
