75 research outputs found
Plano de ação para aconselhamento sobre saúde sexual e reprodutiva de adolescentes do bairro Vila Sarney do municÃpio de São LuÃs-MA
Sem as orientações devidas, os adolescentes, no auge do afloramento dos instintos sexuais, acabam se envolvendo em práticas que resultam em vários problemas como DST, gestações indesejadas e de alto risco, além de outra prática que tem chamado bastante atenção no bairro Vila Sarney em São LuÃs/MA, que é a automedicação com contraceptivos hormonais orais. O atual plano de ação a ser realizado pela equipe composta pelo médico, enfermeiro e os Agentes Comunitários de Saúde objetiva aconselhar e orientar os adolescentes do referido bairro acerca de assuntos relacionados à sua saúde, com ênfase na saúde sexual e reprodutiva, através de palestras nas escolas, panfletagens e compartilhamento de materiais educativos nas redes sociais. Espera-se promover a educação em saúde para os adolescentes, visando reduzir a incidência dos problemas supracitados, principalmente, a prática de automedicação com anticoncepcionais hormonais, que tem se tornado notória no bairro com algumas repercussões muito graves
A putative, novel coli surface antigen 8B (CS8B) of enterotoxigenic Escherichia coli
Enterotoxigenic Escherichia coli (ETEC) strains harbor multiple fimbriae and pili to mediate host colonization, including the type IVb pilus, colonization factor antigen III (CFA/III). Not all colonization factors are well characterized or known in toxin positive ETEC isolates, which may have an impact identifying ETEC isolates based on molecular screening of these biomarkers. We describe a novel coli surface antigen (CS) 8 subtype B (CS8B), a family of CFA/III pilus, in a toxin producing ETEC isolate from a Kenyan collection. In highlighting the existence of this putative CS, we provide the sequence and specific primers, which can be used alongside other ETEC primers previously described
Kinetics of solid-state reactions between zirconium thin film and silicon carbide at elevated temperatures
Solid state reactions between a thin film (133 nm) of Zr and bulk single crystalline 6H-SiC substrates have been studied at temperatures between 600 °C and 850 °C for durations of 30, 60 and 120 min under high vacuum conditions. The deposited film and reaction zones were investigated by Rutherford backscattering spectrometry (RBS) and X-ray diffraction. The RBS spectra were simulated in order to obtain the deposited layer thickness, reaction zone compositions and reaction zone thickness. The as-deposited spectra fit well with those annealed at 600 °C, thus showing there were no reactions taking place. At temperatures of 700 °C and above, Zr reacted with the SiC substrate and formed a mixed layer of Zr carbide (ZrCx) and Zr silicides (ZrSi, Zr2Si and Zr5Si3). Annealing at 850 °C for 240 min revealed that all the deposited Zr had completely reacted. The interface reaction follows the parabolic growth law thereby indicating diffusion controlled reaction kinetics. The activation energy for the diffusion process obtained was 1.6 eV in the relatively narrow temperature range 700–850 °C.http://www.elsevier.com/locate/nimbhb201
The effect of thermal annealing in a hydrogen atmosphere on tungsten deposited on 6H-SiC
Tungsten (W) film was deposited on a bulk single crystalline 6HeSiC substrate and annealed in H2
ambient at temperatures of 700 C, 800 C and 1000 C for 1 h. The resulting solid-state reactions, phase
composition and surface morphology were investigated by Rutherford backscattering spectrometry
(RBS), grazing incidence X-ray diffraction (GIXRD) and scanning electron microscopy (SEM) analysis
techniques. These results are compared with the vacuum annealed results reported in our earlier work.
As-deposited RBS results indicated the presence of W and O2 in the deposited thin film, the GIXRD
showed the presence ofW,WO3, W5Si3 andWC. RBS results indicated the interaction betweenWand SiC
was accompanied by the removal of oxygen at 700 C. The GIXRD analysis indicated the presence of
W5Si3 and WC in the samples annealed at 700 C. At temperatures of 800 C and 1000 C, Wannealed in
a H2 ambient further reacted with the SiC substrate and formed a mixed layer containing silicide phases
and carbide phases, i.e.W5Si3, WSi2, WC and W2C. The SEM micrographs of the as-deposited samples
indicated the W thin film had a uniform surface with small grains. Annealing at 800 C led to the
agglomeration of W grains into clusters making the surface rough.National Research Foundation (NRF) (Grant number: 88661), South Africa.http://www.journals.elsevier.com/vacuum2017-07-30hb2016Physic
In-situ RBS studies of strontium implanted glassy carbon
The diffusion behaviour of strontium in glassy carbon was investigated using in-situ real time
Rutherford backscattering spectrometry. The sample was annealed in vacuum from room
temperature to 650 oC. Diffusion of the implanted strontium towards the bulk was observed
after annealing at temperatures ranging from 450 oC – 560 oC. The diffusion depth was
limited to the end-of-ion-range region where there were still some radiation damage present.No diffusion into the pristine glassy carbon was observed suggestion that diffusion of Sr in
glassy carbon can only occur in regions with radiation damage. Annealing the sample at
higher temperatures higher than 560 oC resulted in migration of the implanted strontium
towards the surface of the glassy carbon substrate. The amount of the accumulated strontium
at the surface increased as the annealing temperature is increased. The RBS spectra obtained
after annealing the sample isothermally at 650 oC for 2 hours show that there was no further
diffusion and accumulation of the strontium during this period.http://www.journals.elsevier.com/vacuum2017-04-30hb2017Physic
Solid state reaction and operational stability of ruthenium Schottky contact-on-6H-SiC under argon annealing
Thin films of ruthenium-on-6-hexagonal silicon carbide (6H-SiC) were analysed by Rutherford backscattering
spectroscopy (RBS) at various annealing temperatures. Some thin film samples were also analysed by scanning
electron microscope (SEM). RBS analysis indicated minimal element diffusion, and formation of ruthenium
oxide after annealing at 500 oC. Large scale diffusion of ruthenium (Ru) was observed to commence at 700 oC.
The SEM images indicated that the as-deposited Ru was disorderly and amorphous. Annealing of the thin film
improved the grain quality of Ru. The fabricated Ru-6H-SiC Schottky barrier diodes (SBD) with nickel ohmic
contacts showed excellent rectifying behaviour and linear capacitance-voltage characteristics up to an annealing
temperature of 900 oC. The SBDs degraded after annealing at 1000 oC. The degradation of the SBDs is
attributed to the inter-diffusion of Ru and Si at the Schottky-substrate interface.http://link.springer.com/journal/116642016-10-31hb201
Migration behaviour of Europium implanted into single crystalline 6H-SiC
Migration behaviour of Europium (Eu) implanted into 6H-SiC was investigated using Rutherford backscattering spectroscopy (RBS), RBS in a channelling mode (RBS-C) and scanning electron microscopy (SEM). Eu ions of 360 keV were implanted into 6H-SiC at 600 °C to a fluence of 1 × 1016 cm−2. The implanted samples were sequentially annealed at temperatures ranging from 1000 to 1400 °C, in steps of 100 °C for 5 h. RBS-C showed that implantation of Eu into 6H-SiC at 600 °C retained crystallinity with some radiation damage. Annealing of radiation damage retained after implantation already took place after annealing at 1000 °C. This annealing of radiation damage progressed with increasing annealing temperature up to 1400 °C. A shift of Eu towards the surface took place after annealing at 1000 °C. This shift became more pronounced and was accompanied by loss of Eu from the surface at annealing temperatures >1000 °C. This shift was accompanied by broadening of Eu peak/Fickian diffusion after annealing at temperatures >1100 °C. The migration of Eu occurring concurrently with the annealing of radiation damage was explained by trapping and de-trapping of Eu by radiation damage.The National Research Foundation (NRF) (grant no: 94104) of South Africahttp://www.journals.elsevier.com/vacuum2018-07-30hj2017Physic
Effect of Xe ion (167 MeV) irradiation on polycrystalline SiC implanted with Kr and Xe at room temperature
The effect of swift heavy ion (Xe 167 MeV) irradiation on polycrystalline SiC individually
implanted with 360 keV Kr and Xe ions at room temperature to fluences of 2×1016 cm-2 and
1×1016 cm-2 respectively, was investigated using transmission electron microscopy (TEM),
Raman spectroscopy and Rutherford backscattering spectrometry (RBS). Implanted
specimens were each irradiated with 167 MeV Xe+26 ions to a fluence of 8.3×1014 cm-2 at
room temperature. It was observed that implantation of 360 keV Kr and Xe ions individually
at room temperature amorphized the SiC from the surface up to a depth of 186 and 219 nm
respectively. Swift heavy ion (SHI) irradiation reduced the amorphous layer by about 27 nm
and 30 nm for the Kr and Xe samples respectively. Interestingly, the reduction in the
amorphous layer was accompanied by the appearance of randomly oriented nanocrystals in
the former amorphous layers after SHI irradiation in both samples. Previously, no similar
nanocrystals were observed after SHI irradiations at electron stopping powers of 33 keV/nm
and 20 keV/nm to fluences below 1014 cm-2. Therefore, our results suggest a fluence threshold for the formation of nanocrystals in the initial amorphous SiC after SHI irradiation.
Raman results also indicated some annealing of radiation damage after swift heavy ion
irradiation and the subsequent formation of small SiC crystals in the amorphous layers. No
diffusion of implanted Kr and Xe was observed after swift heavy ion irradiation.National Research Foundation (NRF)http://iopscience.iop.org0022-37272016-10-20hb201
Interfacial reactions and surface analysis of W thin film on 6H-SiC
Tungsten (W) thin film was deposited on bulk single crystalline 6H-SiC substrate and annealed in vacuum
at temperatures ranging from 700 to 1000 C for 1 h. The resulting solid-state reactions, phase composition
and surface morphology were investigated by Rutherford backscattering spectroscopy (RBS), grazing
incidence X-ray diffraction (GIXRD) and scanning electron microscopy (SEM). XRD was used to identify
the phases present and to confirm the RBS results. The RBS spectra were simulated using the RUMP
software in order to obtain the deposited layer thickness, composition of reaction zone and detect phase
formation at the interface. RBS results showed that interaction between W and SiC started at 850 C. The
XRD analysis showed that WC and CW3 were the initial phases formed at 700 and 800 C. The concentration
of the phases was however, too low to be detected by RBS analysis. At temperatures of 900 and
1000 C, W reacted with the SiC substrate and formed a mixed layer containing a silicide phase (WSi2)
and a carbide phase (W2C). The SEM images of the as-deposited samples showed that the W thin film
had a uniform surface with small grains. The W layer became heterogeneous during annealing at higher
temperatures as the W granules agglomerated into island clusters at temperatures of 800 C and higher.National Research Foundation (NRF), South Africa.http://www.elsevier.com/locate/nimb2017-03-31hb2016Physic
Interface reactions between Pd thin films and SiC by thermal annealing and SHI irradiation
The solid-state reactions between Pd thin films and 6H-SiC substrates induced by thermal
annealing, room temperature swift heavy ion (SHI) irradiation and high temperature SHI
irradiation have been investigated by in situ and real-time Rutherford backscattering
spectrometry (RBS) and Grazing incidence X-ray diffraction (GIXRD). At room temperature,
no silicides were detected to have formed in the Pd/SiC samples. Two reaction growth zones
were observed in the samples annealed in situ and analysed by real time RBS. The initial
reaction growth region led to formation of Pd3Si or (Pd2Si+Pd4Si) as the initial phase(s) to
form at a temperature of about 450 °C. Thereafter, the reaction zone did not change until a
temperature of 640 °C was attained where Pd2Si was observed to form in the reaction zone.
Kinetic analysis of the initial reaction indicates very fast reaction rates of about 1.55×1015
at.cm-2/s and the Pd silicide formed grew linear with time. SHI irradiation of the Pd/SiC
samples was performed by 167 MeV Xe26+ ions at room temperature at high fluences of
1.07×1014 and 4×1014 ions/cm2 and at 400 °C at lower fluences of 5×1013 ions/cm2. The
Pd/SiC interface was analysed by RBS and no SHI induced diffusion was observed for room
temperature irradiations. The sample irradiated at 400 °C, SHI induced diffusion was
observed to occur accompanied with the formation of Pd4Si, Pd9Si2 and Pd5Si phases which
were identified by GIXRD analysis.http://www.elsevier.com/locate/nimb2017-03-31hb2016Physic
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