Irão Nuclear

O Irão é desde 1979 uma potência a ter em consideração. A sua história reflecte a força da nação e a razão pela qual é fortemente reprimido pelos seus pares. A presente dissertação pretende abordar a capacidade nuclear e mais concretamente o seu desenvolvimento pela República Islâmica do Irão, assim como todas as medidas de controlo a esta capacidade, procurando despertar a questão de quem deve ou tem capacidade de determinar a detenção e desenvolvimento de energia nuclear. Vivemos hoje, num mundo multipolar com novos arranjos à estrutura internacional outrora conhecida, verificando-se necessárias novas incursões por estas matérias de forma que as mesmas possam evoluir tanto teórica como praticamente a similar ritmo.

The chemistry of Brazilian leguminosae. LXI. (+)-Methyl Vouacapenate from Vouacapoua pallidior

Thz wood of Vouacapoua pallidior (Leguminosae-Caesalpinioideae) Contains (+)-methyl vouacapenate.

Curare - Botany, Chemistry, and Pharmacology

Some aspects of curare research carried out over the last 25 years are discussed. Accepting a pharmacological rather than purely ethnological definition means, that curares are not limited to South America but that they are also known from Central Africa and South-EastAsia. Among the criteria that have been suggested for classifying South American curares: type of container, geographical origin, botanical sourcesof the active, constituent!, and chemical composition. A combination of botanical and geographical criteria leads to much the same regional ;groupings a combination of criteria involving the type of container and the chemical composition. The active principles in curares may derive from members of thr Loganiaceae (Strychnos) and/or Menispermaceae mainly Chondrodendron and Curarea, but also Abuta,Anomospermum, Cissampelos, Sciadotenia, and Telitoxicum). Certain of the Strychnos dimeric indole alkaloids can undergo a variety of cleavages, oxidations, and isomerizations; hence., some of the compounds obtained by normal isolation procedures one almost certainly artefacts. The different genera of, Menispermaceae a wide range of bisbenzyl and other types of isoquinoline alkaloids. Many of the plant additives also contain a variety of isoquinoline bases, and this has to be taken into account in assessing the contribution these ingredients may make to the ovzJuxll activity of, curare. Loganiaceae-bated curares with toxiferinzas major alkaloid tend to be the most toxic. In the case of Menispermaceae-based products, there-is evidence that the process by which they are made may lead to a considerable increase in the toxicity of the finished poisons as compared with the original plant materials. The mechanism of action of the alkaloids it, outlined, and the role of curare alkaloids in the development of, present-day muscle-relaxant drugs used in surgery is indicated. Attention lb drawn to reported medicinal uses of some of the alkaloid-bearing plants incorporated into curares, suggesting that further evaluation of these plants may be of interest.

The ceramic artifacts in archaeological black earth (terra preta) from Lower Amazon Region, Brazil: chemistry and geochemical evolution

This paper carried out a chemical investigation of archaeological ceramic artifacts found in archaeological sites with Black Earth (ABE) in the Lower Amazon Region at Cachoeira-Porteira, State of Pará, Brazil. The ceramic artifacts, mostly of daily use, belong to Konduri culture (from 900 to 400 years BP). They are constituted of SiO2, Al2O3, Fe2O3, Na2O and P2O5; SiO2 and Al2O3 together add up to 80 % and indicate influence of acid rocks, transformed into clay minerals basically kaolinite. The relative high contents of P2O5 (2.37 % in average) come out as (Al,Fe)-phosphate, an uncommon fact in primitive red ceramics, but found in some roman and egyptian archaeological sites. The contents of the trace elements are similar or below the Earth's crust average. This chemical composition (except P2O5) detaches saprolite material derived acid igneous rocks or sedimentary ones as the main raw material of the ceramics. The contents of K, Na and Ca represent the feldspars and rock fragments possibly introduced into saprolitic groundmass, indicated by mineralogical studies. The presence of cauixi and cariapé as well as quartz sand was confirmed by optical microscope, SEM analyses and by the high silica contents of ceramic fragments. Phosphorus was possibly incorporated into groundmass during cooking of foods, and ABE soil profile formation developed on yellow Latosols. The raw materials and its tempers (cauixi, or cariapé, feldspar, crushed rocks, old ceramic artifacts and quartz fragments) are found close to the sites and therefore and certainly came from them.

Measurements of the nuclear modification factor for jets in Pb+Pb collisions at sNN =2.76TeV with the ATLAS detector

Measurements of inclusive jet production are performed in pp and Pb+Pb collisions at sNN−−−√=2.76 TeV with the ATLAS detector at the LHC, corresponding to integrated luminosities of 4.0 pb−1 and 0.14 nb−1 , respectively. The jets are identified with the anti-kt algorithm with R=0.4, and the spectra are measured over the kinematic range of jet transverse momentum 32nuclear modification factor, RAA, is evaluated and jets are found to be suppressed by approximately a factor of two in central collisions compared to pp collisions. The RAA shows a slight increase with pT and no significant variation with rapidity.

DOTA-based Ga(III) and Gd(III) chelates for medical imaging (PET, SPECT and MRI)

PhD Thesis in Sciences Specialization in Chemistry

The mineralogy and chemistry of the German and Portuguese tiles used to face a historic building in the Amazon region and their natural susceptibility to tropical weathering

During the 19th century, the most prominent buildings of the city of Belém were faced entirely with tiles manufactured in Portugal and Germany, which now exhibit distinct degrees of degradation. The Pinho mansion is one of the most important of these buildings and was selected for the investigation of the action of the tropical Amazonian climate on the degradation of the tiles. To achieve this objective, the tiles were mapped for organic and inorganic degradation, and samples were collected for analysis. The minerals were determined by XRD, the chemical composition by classical wet methods and SEM/EDS, and the microorganisms under the microscope. The results show that the German and Portuguese tiles are quite different in their composition. While both ceramic bodies are composed of SiO2 and Al2O3, CaO was found only in the Portuguese tile. The low Na2O and K2O contents indicate the addition of materials to reduce the fusion temperature. SiO2 and PbO are the main constituents of the glaze, with CoO and FeO being added as pigment. The ceramic body of the German tiles is constituted of quartz, mullite, and cristobalite, in contrast with the Portuguese tiles, which are made of quartz, gehlenite, diopside, calcite, and feldspars. The glazes are XRD-amorphous. The chemical and mineralogical differences between the German and Portuguese tiles indicate that they were produced from different raw materials under distinct thermal processes. The most prominent weathering-related modifications are the thin layers (German tiles), oxidation stains, dark stains, the detachment of the tile (Portuguese tiles), loss of the glaze and powdering of the ceramic body (Portuguese tiles) through the establishment of Cyanophyta and Bacillariophyta.. The distinct degradation patterns of the tiles exposed to the tropical Amazon climate are a consequence of their distinct mineralogy and chemistry.

PEGylated DOTA-AHA-based Gd(III) chelates – A relaxometric study

Three PEGylated derivatives of 1,4,7,10-tetraazacyclododecane-1-((6-amino)hexanoic)-4,7,10-triacetic acid) (DOTA-AHA) with different molecular weights were prepared and characterized. Their Gd(III) chelates were studied in aqueous solution using variable-temperature 1H nuclear magnetic relaxation dispersion (NMRD) and 17ONMR spectroscopy in view of the determination of their relaxivity and the parameters that govern it. The relaxivity varied from 5.1 to 6.5 mM-1.s-1 (37 ºC and 60 MHz) with the increasing molecular weight of the PEG chain, being slightly higher than that of the parent chelate Gd(DOTA-AHA), due to a small contribution of a slow global rotation of the complexes. A variable temperature 1H NMR study of several Ln(III) chelates of DOTA-A(PEG750)HA allowed the determination of the isomeric M/m ratio (M = square antiprismatic isomer and m = twisted square antiprismatic isomer, the latter presenting a much faster water exchange) which for the Gd(III) chelate was estimated in circa 1:0.2, very close to that of [Gd(DOTA)]-. This explains why the PEGylated Gd(III) chelate has a water rate exchange similar to that of [Gd(DOTA)]-. The predominance of the M isomer is a consequence of the bulky PEG moiety which does not favor the stabilization of the m isomer in sterically crowded systems at the substituent site, contrary to what happens with less packed asymmetrical DOTA-type chelates with substitution in one of the four acetate C(α) atoms.

Ressonância nuclear magnética no diagnóstico de pseudoaneurisma de ventrículo esquerdo. Antigo problema, nova opção

Paciente feminina, 67 anos, internada por infarto agudo do miocárdio de parede lateral, com edema agudo de pulmão e evolução para choque cardiogênico nas primeiras horas. Ecocardiograma transesofágico e ressonância nuclear magnética confirmaram o diagnóstico de pseudoaneurisma de ventrículo esquerdo. A paciente foi submetida a tratamento cirúrgico com sucesso.

Genetic diversity and population structure in Vicia faba L. landraces and wild related species assessed by nuclear SSRs

Research Article

Estudio básico y aplicado de polímeros elastómeros mediante la Técnica de Resonancia Magnética Nuclear (RMN)

Los polímeros son materiales que poseen una variedad muy grande de aplicaciones. Por esta razón, el estudio de sus propiedades físicas y químicas resulta de gran interés. Un polímero es una macromolécula cuyo peso molecular puede llegar a varios millones de umas. Mediante la selección de el o los monómeros y de su secuenciamiento en el proceso de polimerización (microestructura del polímero), se puede lograr que el material tenga propiedades predeterminadas. Es posible, entonces, encontrar o desarrollar polímeros para las más variadas aplicaciones: elásticos, rígidos, resistentes a la temperatura, conductores, aisladores, inertes, etc. (...) La Resonancia Magnética Nuclear (RMN) de alta resolución es una de las técnicas más poderosas para la caracterización de los polímeros, brindando información sobre la microestructura y la dinámica de estas macromoléculas, tanto cuando se encuentran en estado sólido como cuando están disueltas en soluciones líquidas. El entendimiento de la microestructura de un polímero es de interés porque ella está íntimamente relacionada con las propiedades macroscópicas del material. Por otra parte, la microestructura de un polímero depende del proceso de polimerización utilizado y en consecuencia, es posible obtener información sobre los mecanismos de reacción química que ocurren durante su síntesis, dentro de los reactores de polimerización. NMR permite, también, obtener información detallada sobre la dinámica de los polímeros. La gran longitud de los polímeros hace que su dinámica molecular sea sumamente compleja. Sin embargo, mediante el empleo de secuencias de pulsos particulares y mediciones de los tiempos de relajación característicos de los espines nucleares, se obtiene información sobre la dinámica de la macromolécula, de los segmentos que la componen y de los grupos colgantes que pueda poseer. Objetivos Generales y Específicos El trabajo a realizar en el período correspondiente al subsidio solicitado, es la continuación de las investigaciones comenzadas en septiembre de 1995. Se avanzará en el entendimiento de los elastómeros que se están estudiando actualmente. El estudio abarca los elastómeros sin tratamientos térmicos y con tratamientos térmicos (vulcanizados).

Investigación básica y aplicada, y desarrollos empleando la Resonancia Magnética Nuclear

La Resonancia Magnética Nuclear (RMN) es una técnica experimental de gran utilidad y de amplia aplicación a un variado campo de investigación multidisciplinario. En particular la RMN en sólidos requiere de la disponibilidad de un complejo equipamiento que contempla sofisticados accesorios experimentales. Sin embargo, se compensa el gasto que involucra la compra de equipamiento con el amplio número de usuarios del mismo. Este PIT refleja la necesidad de un equipo permanente que tienen los distintos investigadores que forman parte de este proyecto. Las tareas de investigación se desarrollarán en el Laboratorio de Investigación y Servicios de Resonancia Magnética Nuclear (LANAIS de RMN) de la Facultad de Matemática, Astronomía y Física (FAMAF) de la UNC. La adquisición del equipamiento permanente solicitado es de fundamental importancia para la concreción de los planes de investigación como también a la formación de recursos humanos a nivel de doctorado en Física. El Objetivo General de este PIT es el de contribuir de una forma centralizada al mantenimiento del equipamiento con que cuenta este LANAIS de RMN, a incorporar mejoras que sean necesarias y a adquirir accesorios que incrementen sus posibilidades, que sean de uso y utilidad general a los proyectos antes mencionados y que permitan realizar nuevos experimentos, no factibles actualmente. El Objetivo Específico a lograr en estos tres años es el de incorporar y desarrollar la capacidad de realizar estudios de alta resolución de líquidos, debiéndose adquirir un cabezal de banda ancha que cubra el rango de frecuencias desde Ag-109 hasta P-31 (15-120 MHz), para portamuestras de 10 mm de diámetro y con capacidad para variar la temperatura alrededor de la temperatura ambiente. Este cabezal tiene uso inmediato en los siguientes proyectos: * Estudio de polimorfismos y estructuración del agua en polímeros. * Propiedades estructurales y dinámicas de organizaciones supramoleculares de interés biológico. * Estudios por Resonancia Magnética Nuclear. * Utilización de Resonancia Magnética Nuclear de sólidos en el campo farmacéutico.