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Search Results: 1 - 10 of 144450 matches for " F.F.; Pierna "
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Corrosion Behaviour of Fe/Co Based Amorphous Metallic Alloys in Saline Solutions: New Materials for GMI Based Biosensors
Marzo,F.F.; Pierna,A.R.; Barranco,J.; Vara,G.; Lorenzo,A.; Pérez,A.; García,J.A.;
Portugaliae Electrochimica Acta , 2007,
Abstract: the objective of this investigation has been the study of corrosion resistance of fe2.5co64.5cr3si15b15, fe3co67cr3si15b12 and fe5co70si15b10 amorphous metallic alloys obtained by the melt spinning technique, used as based materials to create a new type of giant magnetoimpedance (gmi) biosensor. the corrosion behaviour has been studied in phosphate buffered saline (pbs) solutions at ph 7.3 and 37.5 oc. the electrochemical characterization of alloys has been made by means of dc techniques, obtaining the corrosion potential, pitting and protection potentials, as well as the perfect and imperfect passive regions of alloys. in this work, the experimental results obtained are discussed in order to study their corrosion behaviour in artificial biological solutions and thus determine their possible use as gmi-biosensor prototype materials.
Toxicological effects and resistance to pyrethroids in Boophilus microplus from Goiás, Brazil
Fernandes, F.F.;
Arquivo Brasileiro de Medicina Veterinária e Zootecnia , 2001, DOI: 10.1590/S0102-09352001000500004
Abstract: in order to monitor the susceptibility of boophilus microplus to acaricides and improve control measures, the effects of cypermethrin, deltamethrin and permethrin on larvae obtained in the city of goiania in the brazilian state of goiás were studied. although these pyrethroids are already sold as acaricides, their cost-benefit efficiency has been questioned. fasting 14-21 day-old larvae were immersed in solutions of the acaricides under test, maintained at 27±1° c, and relative humidity over 80%, and observed under the stereoscope within an apparatus originally designed for studying the non-parasitic phase of the tick life cycle. the observed toxicological effects were: excitability, repetitive motion, decreased motor ability, detachment, paralysis, knock-down and cuticular proliferation of liquids and gases. the materials used in the manufacture of this apparatus consisted of disposable petri dishes, "organza" cloth and paraffin, none of which are toxic to tick larvae. mean death rates after 24h were 76.3%, 87.5%, 77.6%, 91.2%, 86.2% and 100% for 25 and 50ppm deltamethrin, 150 and 300ppm cypermethrin and 1250 and 2500ppm permethrin, respectively. the ticks were resistant to commercial concentrations of deltamethrin and cypermethrin. only 2500ppm permethrin produced the mortality recommended by the brazilian ministry of agriculture.
Atividade in vitro de permetrina, cipermetrina e deltametrina sobre larvas de Rhipicephalus sanguineus (Latreille, 1806) (Acari, Ixodidae)
Fernandes, F.F.;
Arquivo Brasileiro de Medicina Veterinária e Zootecnia , 2000, DOI: 10.1590/S0102-09352000000600012
Abstract: aiming at monitoring the susceptibility, increasing the control and evaluating the toxicological effects, of different concentrations of three pyrethroids were investigated in vitro against rhipicephalus sanguineus larvae using concentrations formulated for cattle, dogs and household use. a total of 1,604 15-21 day-old fasting larvae, obtained by artificial infestation in dogs, was immersed in the solutions. larvae were then maintained in bod incubators inside experimental devices, constituted by disposable petridishes, filter paper and paraffin, and observed on the stereomicroscope during a 24-hour period. the larvae have shown excitability, repetitive movements, decrease of locomotion, detachment, paralysis, knock-down and production of gases and liquid in the cuticle. mortality after 24 hours was 86.9% (1250ppm) and 100.0% (2500ppm) for permethrin; 80.3% (150ppm) and 86.0% (300ppm) for cipermethrin; and for deltamethrin 68.2% (25ppm) and 78.0% (50ppm). mortality was not observed in the control group.
Reasons for Increase in Adolescence Sexual Activities in Nigeria
F.F. Akanle
Pakistan Journal of Social Sciences , 2012,
Abstract: This study investigated the reasons for increase in adolescence sexual activities in Nigeria. The research design was a descriptive survey type. The population for the study comprised of all parents and counsellors who are married sandwich students in their undergraduate studies of the University of Ado-Ekiti and their lecturers. The sample consist of 127 students and 23 counsellors who are married parents and who had children. The research instrument was a self construct are tagged Sexuality and Parents Questionnaire (SAPQ). The questionnaires were validated using face and content validity procedures. The instrument has a reliability coefficient of 0.80. The instrument was administered by the research and 4 research assistants. The analysis of the general questions was done through the use of frequency counts and percentages while the Hypotheses were tested using chi-square. The analyses revealed that a high percentage at parents and counsellors agree that youths do not adhere to the idea of "no sex guide", that teenage sex has become a way of life and that the role which sex play in the lives of youths and the influence of social forces contribute greatly to the non adherence of "no to sex guide among youths. There was a significant difference in the reason for non adherence of youths to the idea of no sex guide, there was a significant difference in the ways suggested for curbing premarital sexual behaviour by counsellors and parents. The analyses shows that majority of the respondents claimed the provision of sexuality education can curb premarital sex while parental guidance at early age could also assist in curbing premarital sex. Based on these findings it was recommended that sexuality education should be provided on the media, at school so as to assist adolescent to make informed about sexual issues so that they can adhere to "no sex guide" on sexual behaviour until they become more matured to handle sexual issues.
HAT veertig jaar — 'n persoonlike oorsig
F.F Odendal
Lexikos , 2011, DOI: 10.5788/16--663
Abstract: Opsomming: In 2005 was dit 40 jaar sedert die verskyning van die eerste uitgawe van HAT (Verklarende Handwoordeboek van die Afrikaanse Taal), onder redakteurskap van P.C. Schoonees, C.J. Swanepoel, S.J. du Toit en C.M. Booysen. Die ontwikkeling voor hierdie publikasie en daarna van HAT 2 en 3 onder die alleenredakteurskap van F.F. Odendal en van HAT 4 en 5 onder die gesamentlike redakteurskap van Odendal en R.H. Gouws, word oorsigtelik geskets. Sleutelwoorde: HAT (VERKLARENDE HANDWOORDEBOEK VAN DIE AFRIKAANSE TAAL), WAT (WOORDEBOEK VAN DIE AFRIKAANSE TAAL) Abstract: HAT Forty Years ? A Personal Survey. In 2005 it has been 40 years since the publication of the first edition of HAT (Verklarende Handwoordeboek van die Afrikaanse Taal), then with P.C. Schoonees, C.J. Swanepoel, S.J. du Toit and C.M. Booysen as editors. The development before this publication and subsequently of HAT 2 and 3 under the sole editorship of F.F. Odendal and of HAT 4 and 5 under the combined editorship of Odendal and R.H. Gouws is synoptically sketched. Keywords: HAT (VERKLARENDE HANDWOORDEBOEK VAN DIE AFRIKAANSE TAAL), WAT (WOORDEBOEK VAN DIE AFRIKAANSE TAAL)
Atividade in vitro de permetrina, cipermetrina e deltametrina sobre larvas de Rhipicephalus sanguineus (Latreille, 1806) (Acari, Ixodidae)
Fernandes F.F.
Arquivo Brasileiro de Medicina Veterinária e Zootecnia , 2000,
Abstract: Investigaram-se os efeitos toxicológicos in vitro de três piretróides em diferentes concentra es, formulados para uso pecuário, domiciliar e em c es, sobre larvas de R. sanguineus, objetivando monitorar sua suscetibilidade e fomentar seu controle. Utilizaram-se 1.604 larvas em jejum, com 15 a 21 dias, obtidas por infesta o artificial em c o, imersas nas solu es testadas, contidas em dispositivos constituídos por placa de Petri descartável, papel filtro e parafina, mantidas em incubadoras do tipo BOD e observadas ao estereoscópio por 24h. Observaram-se excitabilidade, movimenta o repetitiva, diminui o da locomo o, desprendimento, paralisia, "knock-down" e prolifera o cuticular de gases e líquidos. A mortalidade na 24a hora foi de 86,9%, 100,0%, 80,3%, 86,0%, 68,2% e 78,0%, respectivamente, para permetrina 1250ppm e 2500ppm, cipermetrina 150ppm e 300ppm, e deltametrina 25ppm e 50ppm. N o houve mortalidade no grupo controle.
Toxicological effects and resistance to pyrethroids in Boophilus microplus from Goiás, Brazil
Fernandes F.F.
Arquivo Brasileiro de Medicina Veterinária e Zootecnia , 2001,
Abstract: In order to monitor the susceptibility of Boophilus microplus to acaricides and improve control measures, the effects of cypermethrin, deltamethrin and permethrin on larvae obtained in the city of Goiania in the Brazilian state of Goiás were studied. Although these pyrethroids are already sold as acaricides, their cost-benefit efficiency has been questioned. Fasting 14-21 day-old larvae were immersed in solutions of the acaricides under test, maintained at 27±1° C, and relative humidity over 80%, and observed under the stereoscope within an apparatus originally designed for studying the non-parasitic phase of the tick life cycle. The observed toxicological effects were: excitability, repetitive motion, decreased motor ability, detachment, paralysis, knock-down and cuticular proliferation of liquids and gases. The materials used in the manufacture of this apparatus consisted of disposable Petri dishes, "organza" cloth and paraffin, none of which are toxic to tick larvae. Mean death rates after 24h were 76.3%, 87.5%, 77.6%, 91.2%, 86.2% and 100% for 25 and 50ppm deltamethrin, 150 and 300ppm cypermethrin and 1250 and 2500ppm permethrin, respectively. The ticks were resistant to commercial concentrations of deltamethrin and cypermethrin. Only 2500ppm permethrin produced the mortality recommended by the Brazilian Ministry of Agriculture.
Distribui??o de metais pesados na vegeta??o metalófica de Carajás
Silva, Manoela F.F. da;
Acta Botanica Brasilica , 1992, DOI: 10.1590/S0102-33061992000100009
Abstract: this study was conduted in the north range (serra norte), one of the geographic formations of the carajás mineral complex, located in the municipality of paraupebas, state of pará, brazil. concentrations of heavy metals were determined in plant tissues and soils. the five species selected for study were: bauhinia pulchella (leguminosae caesalpioideae), cuphea annullata (lythraceae) - ipomoea cavalcantei (convolvulaceae) - mimosa acutistipula var. ferrea (leguminosae mimosoideae) and callisthene minor (vochysiaceae). the metals analyzed were iron (fe), manganese (mn), copper (cu), nickel (ni), chorium (cr) and lead (pb). the levels of exchangeable metals in the soil were similar at the edge and in the center of the mineral deposit. the tissues of the five plant species analyzed had abnormally high levels of fe, ni and cr. each of the plant species tested is tolerant of the metals considered. it is assumed that the interaction of these metals neutralizes their damaging effects on the plants studied. this interaction is a form of tolerance. baunhia pulchella surpassed the other species in the accumulation of nickel. it is possible that the high concentration if ni in this plant is related to the xerophytic conditions of the "canga' environment.
Modelo Termo-Mecánico para un Manipulador Tipo Dieléctrico
Kiyama,F.F.; Vargas,E.;
Información tecnológica , 2004, DOI: 10.4067/S0718-07642004000500004
Abstract: a mathematical model is proposed for the estimation of the position of one of the degrees of freedom of a manipulator which is operated by a cushion-type pneumatic cylinder. pneumatic modeling is based on the thermodynamic principle of conservation of mass and energy . mechanical modeling is constructed based on the newton-euler formulation, and a variant of the estimated friction curve of van der vrande is proposed for the system. integral forms of the models are analyzed using simulation, and the results are compared with results obtained on a prototype manipulator which was built and instrumented for this purpose. it is concluded that the thermo-mechanical model obtained satisfactorily describes the position and the force exerted by the manipulator
Steps in the formation of neurites and synapses studied in cultured leech neurons
De-Miguel, F.F.;
Brazilian Journal of Medical and Biological Research , 2000, DOI: 10.1590/S0100-879X2000000500002
Abstract: leech neurons in culture have provided novel insights into the steps in the formation of neurite outgrowth patterns, target recognition and synapse formation. identified adult neurons from the central nervous system of the leech can be removed individually and plated in culture under well-controlled conditions, where they retain their characteristic physiological properties, grow neurites and form specific chemical or electrical synapses. different identified neurons develop distinctive outgrowth patterns that depend on their identities and on the molecular composition of the substrate. on native substrates, the patterns displayed by these neurons reproduce characteristics from the adult or the developing neurons. in addition, the substrate may induce selective directed growth between pairs of neurons that normally make contact in the ganglion. upon contact, pairs of cultured leech neurons form chemical or electrical synapses, or both types depending on the neuronal identities. anterograde and retrograde signals during membrane contact and synapse formation modify the distribution of synaptic terminals, calcium currents, and responses to 5-hydroxytryptamine.
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