Hidroquímica do rio Solimões na região entre Manacapuru e Alvarães: Amazonas - Brasil

Este trabalho discute as características físico-químicas das águas dos rios Solimões, Purus e seus afluentes, coletadas em novembro de 2004 no Estado do Amazonas, entre as cidades de Manacapuru-Alvarães e Anamã-Pirarauara. Foram realizadas análises físico-químicas (temperatura, pH, condutividade elétrica, turbidez, Ca2+, Na+, K+, Mg2+, HCO3-, SO42-, Cl-), de elementos-traço (Li, B, Al, Sc, V, Cr, Mn, Fe, Co, Cu, Zn, As, Se, Rb, Sr, Mo, Cd, Sb, Cs, Ba, Pb, La, Ce e U) e isótopos de estrôncio. Os parâmetros analisados e a composição química mostram que as águas dos rios e igarapés da região central da Amazônia são quimicamente distintas entre si. As águas brancas do Solimões são cálcicas-bicarbonatadas e as do Purus bicarbonatadas, os respectivos afluentes são sódico-potássico-bicarbonatados e sódico-potássico-sulfatados. Isso acarreta águas brancas fracamente ácidas a neutras e mais condutivas, enquanto as pretas são menos mineralizadas, mais ácidas, especialmente as do Purus. O Ba, Sr, Cu, V e As mais elevados diferenciam as águas brancas do Solimões das do Purus, bem como os afluentes do primeiro em relação ao segundo. Esse conjunto de características indicam que tanto o Solimões, como o Purus e os respectivos afluentes, estão submetidos a condições geológicas/ambientais distintas. A influência do aporte de sedimentos dos Andes é diluída ao longo da bacia do Solimões e se reflete na formação das várzeas dos Solimões e Purus. Por outro lado as rochas crustais, representadas pelos escudos das Guianas e Brasileiro também contribuem, mas em menor proporção.

Strontium isotope stratigraphy of the Pelotas Basin

Dados da razão isotópica de estrôncio foram obtidos a partir da análise de conchas de foraminíferos recuperadas dos depósitos terciários da Bacia de Pelotas visando o refinamento do arcabouço cronoestratigráfico dessa seção. Este artigo representa a primeira abordagem à obtenção de idades numéricas para esses estratos. A estratigrafia de isótopos de estrôncio permitiu a identificação de oito hiatos deposicionais na seção Eoceno-Plioceno, aqui classificados como desconformidade, além de uma seção condensada. O reconhecimento de hiatos deposicionais representa um importante avanço, considerando a baixa resolução cronoestratigráfica da seção cenozóica da Bacia de Pelotas. Além disso, foi identificado um substancial aumento na taxa de sedimentação na seção neomiocênica. Tendências gerais de paleotemperatura e produtividade foram identificadas com base em dados das razões isotópicas de oxigênio e carbono da seção Oligoceno-Mioceno. Essas tendências são coerentes com eventos globais, evidenciando as condições ambientais durante a sedimentação.

Síntese, caracterização estrutural e análise do potencial catalítico do SrTiO3 e das Perovskitas duplas de Sr1-xKxTiCux/2O3, onde x = 0,2; 0,3 e 0,5, na preparação de biodiesel

Pós-graduação em Química - IBILCE

Influência do lantânio nas propriedades estruturais do SrSnO3

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Tratamento de modificação de eutético da liga AA356

Alloy Al-7%Si-0,3Mg (AA356), having an excellent combination of properties such as low solidification shrinkage and good fluidity, good weldability, high wear resistance, high strength to weight particularly in the automotive and aerospace engineering. The refinement of the structure aluminum silicon eutectic alloy is a fairly common practice in the casting, through the treatment knows as modification. You can get the modification for the addition of chemicals and rare earths, these have the ability to modify the structure of the eutectic, but only sodium and strontium produce a strong action modifier when used in low concentrations. The modifying effect of silicon grain turns into a fibrous form branched and enveloped by the metal matrix in the form of a composite structure that has the highest limit of tensile strength, ductility and machinability. This work will be obtained AA356 alloy ingots using two different types of molds: metal mold and sand mold. Macrographs will be made in ingots obtained for observation of the macrostructures obtained in both types of ingots. Will be sampled at strategic locations of the ingots to correlate microstructure and cooling rate. The results showed that the material of the ingot has a strong influence on the resulting micro-andmacrostructure

Estudo do efeito do modificador Al-Sr no tratamento de modificação do eutético da liga AA356

The AA356 alloy is an alloy widely used in the automotive industry and aerospace due to its excellent mechanical properties. Refining the structure of eutectic silicon aluminum alloys is a fairly common practice in the foundry through treatment known as modification. This can be achieved by modifying agent adding chemicals such as contained in groups I and IIa of the periodic table and rare earths (europium, céreioi, praseodymium, neodymium, etc.). Has the ability to modify the structure of the eutectic, but only sodium and strontium produce an action modifier strong when used in low concentrations. The modifying effect of the shafts turn silicon into a fibrous form and branched surrounded by metallic matrix in the form of a composite structure that has the highest limit of tensile strength, ductility and machinability. In this work will be obtained ingots with and without the modifier type Al-10% Sr, made in sand molds and are generated and analyzed cooling curves and also the study of the macrostructure and microstructure of the solidified material. It was found that by adding the Al-Sr made shorten the solidification time and lower the grain size

Strontium isotopes measurement from bunker cave system: a contribution for the multi-proxy paleoclimate research of Central Europe

In recent years speleothem has been intensely studied due to its great potential of registering paleoclimate proxies but some considerably uncertaintiesregarding speleothem proxy interpretation still exist. In order to minimize these uncertainties, multi-proxy approach has been used. Here is presented the strontium isotope record from Bunker cave, northwest Germany. This cave was previously studied and has proved well record paleoclimate changes during Holocene for central Europe.87Sr/86Sr ratio is presented for rain water, A-horizon soil (water and leachate), C-horizon soil (water and leachate), host rock and host rock leachate, drip water and from a stalagmite (Bu4) previously dated covering the Holocene. Upper soil presented the higher values in contrast with host rock (lower values). Drip water and C-horizon presented intermediated ratios. Sr isotopesare used to track the source of 87Sr/86Sr in the Bunker system, resulting in a mixture between A-horizon soil, C-horizon soil and host rock. A decreasing trend in Bu4 indicates change in the Sr source in the system

Análise dosimétrica de aplicadores de Betaterapia

Betatherapy is a special medical technique using a radioactive source of strontium-90 for the treatment of superficial lesions, especially in dermatology and ophthalmology. Strontium-90 sources emit β radiation, which possesses high ionization power, but a very short distance propagation into matter. This work presents a method of dosimetric analysis of betatherapy using strontium- 90-based instrumentation, commonly used against superficial diseases, such as keloid and pterygium, aiming the description of the dosimetry analysis procedures, which can be easily implemented on tradiotherapy services that offers the betatherapy treatment. IBF-MEDIX radiographic films (conventional films) were exposed to betatherapy applicators during different time intervals according to the activity of the source, and afterwards the optical densities (O. D.) of the radiographic images were measured using an optical densitometer MACBETH. Therefore, the parameters used to make the dosimetric analysis in betatherapy were standardized, as the exposure time depended on the geometry and size of the source, providing an efficient and fast method of dosimetric analysis of the betatherapy equipment of the services, the majority of which do not have the scientific structure to perform this study

Métodos de Calibração e Dosimetria de Aplicadores de Betaterapia

The sources of betatherapy for clinical use in Brazil are, the vast majority of strontium-90, radioactive element that is not produced in the country, and therefore requires importation of international laboratories accredited by the International Atomic Energy Agency (IAEA).The use of these resources is always limited the crediting of characteristic values supplied by the manufacturer tables that provide the nominal value of activity and dose distribution to determine the irradiation time of the injury. The Institute of Nuclear Energy Research (IPEN / CNEN-SP) has recently researching the emission profile of these types of radiation sources, and some jobs are being developed with ionization chambers extrapolation for the purpose of standardizing a systematic calibration sources betatherapy. Other studies using parallel measures dosimeters (TLD's) and simulations with the Monte Carlo method. Radiological films have also been used in studies of applicators dosimetric analysis of strontium-90. This paper seeks to analyze the different methods for calibration of applicators betatherapy, already consolidated in studies by examining the advantages and disadvantages of each procedure

Inorganic elemental analysis and identification of residual monomers released from different glass ionomer cements in cell culture medium

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Hipersensibilidade dentinária cervical: em busca de um tratamento eficaz

The knowledge of the etiology of any disease or condition is paramount to a safe and effective treatment. This literature review aims to show some options to treat dentine hypersensitivity (HSDC). The loss of cervical enamel and cementum exposure of tubules leads to a painful condition and patient discomfort, called HSDC. This loss of tooth structure occurs due to formation of cervical lesions in cases of gingival recession, abrasion, erosion, or abfraction by the association of two or more factors. Some treatments are not effective, but there are effective therapies, such as: application of ferric oxalate, potassium oxalate, potassium nitrate, fluoride varnish, solutions of calcium phosphate, adhesives and Bonding procedures. Therefore, the identification and removal of etiological factors is essential to successful treatment of HSDC normally associated to tubules obliterate and consequent reduction of fluid motion within the dentin.

Beta therapy with 90 strontium as single modality therapy for canine squamous cell carcinoma in third eyelid

The purpose was to evaluate the effectiveness of beta-radiation with strontium-90 as single modality treatment of canine third eyelid squamous cell carcinoma (SCC). Nine dogs diagnosed with third eyelid SCC were treated with strontium-90. Radiation therapy was administered in four fractions of 100cGy per site every four days and at a depth of 0.2cm (Strontium-90 build' up) in each fraction. Radiation with beta therapy was well tolerated in all animals with no occurrence of radiation induced cataracts. In all cases, there were increased signs of conjunctival inflammation around the mass, which subsided with topical anti-inflammatory. Two dogs required surgical treatment for local tumor recurrence at 150 days and 352 days. In the remaining seven cases, disease free interval ranged from 1239 days to 2555 days. Beta therapy using 90Sr may be a valid alternative for the treatment of third eyelid SCC in dogs

Efeito de diversos protocolos de dessensibilização dentinária na obliteração de túbulos dentinários, resistência de união do sistema adesivo e formação de camada hibrida na dentina cervical

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeito de diversos protocolos de dessensibilização dentinária na obliteração de túbulos dentinários, resistência de união do sistema adesivo e formação de camada hibrida na dentina cervical

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Collective effects in light scattering from cold strontium clouds

A cold atomic cloud is a versatile object, because it offers many handles to control and tune its properties. This facilitates studies of its behavior in various circumstances, such as sample temperature, size and density, composition, dimensionality and coherence time. The range of possible experiments is constrained by the specifications of the atomic species used. In this thesis presents the work done in the experiment for laser cooling of strontium atoms, focusing on its stability, which should provide cold and ultracold samples for the study of collective effects in light scattering. From the initial apparatus, innumerous changes were performed. The vacuum system got improved and now reached lower ultra high vacuum due to the pre-baking done to its parts and adding a titanium-sublimation stage. The quadrupole trap were improved by the design and construction of a new pair of coils. The stability of the blue, green and red laser systems and the loss prevention of laser light were improved, giving rise to a robust apparatus. Another important point is the development of homemade devices to reduce the costs and to be used as a monitor of different parts of an cold atoms experiment. From this homemade devices, we could demonstrate a dramatic linewidth narrowing by injection lock of an low cost 461 nm diode laser and its application to our strontium experiment. In the end, this improved experimental apparatus made possible the study of a new scattering effect, the mirror assisted coherent back-scattering (mCBS).