Abstract Carbonaceous porous materials are strong candidates for producing low-cost, lightweight, and sustainable electromagnetic (EM) absorbing materials. This work investigates the production of radar-absorbing materials (RAM) by a simple method. Sustainable carbon xerogel (CX) was synthesized from tannin, a biosourced molecule. CX and commercial carbon nanotube (CNT) were embedded in a silicone matrix at proportions of 10 and 15 wt.% of CX and 0.1 wt.% of CNT to produce flexible composites. The morphology and structure of the carbonaceous materials were evaluated by field-emission scanning electron microscopy (FEG-SEM), Raman spectroscopy, X-ray diffraction (XRD), textural properties by N2 adsorption-desorption isotherms, and mercury porosimetry. The electromagnetic characterization of the composites was analyzed by a vector network analyzer (VNA) in the Ku-band. The results demonstrated that an increased concentration of CX in the composite improved reflection loss reaching -43.19 dB at 13.79 GHz.

ABSTRACT Anthropogenic activity, such as accidental oil spills, are typical sources of urban mangrove pollution that may affect mangrove bacterial communities as well as their mobile genetic elements. To evaluate remediation strategies, we followed over the time the effects of a petroleum hydrocarbon degrading consortium inoculated on mangrove tree Avicennia schaueriana against artificial petroleum contamination in a phytoremediation greenhouse experiment. Interestingly, despite plant protection due to the inoculation, denaturing gradient gel electrophoresis of the bacterial 16S rRNA gene fragments amplified from the total community DNA indicated that the different treatments did not significantly affect the bacterial community composition. However, while the bacterial community was rather stable, pronounced shifts were observed in the abundance of bacteria carrying plasmids. A PCR-Southern blot hybridization analysis indicated an increase in the abundance of IncP-9 catabolic plasmids. Denaturing gradient gel electrophoresis of naphthalene dioxygenase (ndo) genes amplified from cDNA (RNA) indicated the dominance of a specific ndo gene in the inoculated petroleum amendment treatment. The petroleum hydrocarbon degrading consortium characterization indicated the prevalence of bacteria assigned to Pseudomonas spp., Comamonas spp. and Ochrobactrum spp. IncP-9 plasmids were detected for the first time in Comamonas sp. and Ochrobactrum spp., which is a novelty of this study.

ABSTRACT: Multifunctional composites combine structural and other physicochemical properties, with major applications in aeronautical, space, telecommunication, automotive, and medical areas. This research evaluates electromagnetic properties of multifunctional composites based on glass fiber woven fabric pre-impregnated with epoxy resin laminated together carbon fiber non-woven veil metalized with Ni. In this way, searching for possible application as radar absorbing structures or electromagnetic interference shielding structures. The scattering parameters, in the frequency range of 8.2 to 12.4 GHz, show that the epoxy resin/glass fiber prepreg allows the transmission of the electromagnetic waves through its microstructure, independently of the glass fiber reinforcement orientation (98% transmission, S24 = −0.09 dB). However, the carbon fiber/Ni veil shows highly reflector behavior (91% reflection, S22 = −0.43 dB). Energy dispersive spectroscopy of the veil, before and after nitric acid attacks, confirmed the Ni coating removal from the carbon fiber surface. Still, the scattering parameters show reflector behavior (77% reflection, S22 = −1.13 dB), attributed to the electrical conductivity of carbon fibers. Multifunctional composites based on glass fiber/epoxy/carbon fiber/Ni veil laminates were processed by hot compression molding. The scattering parameters show that the laminates do not behave as good radar absorbing structures. Nevertheless, the laminates present promising results for application as light weight and low thickness structural composites with electromagnetic interference shielding effectiveness (91.4% reflection for 0.36 mm thickness and 100% for ∼ 1.1 mm) for buildings, aircraft, and space components.

Importantes processos erosivos após o Cretáceo foram responsáveis pela evolução da paisagem na região de João Pinheiro, onde ocorrem os depósitos de espongilito. O avanço desses processos, aliados às rochas carbonáticas do substrato, permitiu o desenvolvimento de feições cársticas negativas, onde foram instaladas as lagoas formadoras dos depósitos de espongilito. Com base no tratamento de imagens de satélite aliado a trabalhos de campo, quatro morfodomínios geomorfológicos foram identificados na área: i) morfodomínio 1, representado por platôs associados aos arenitos do Grupo Areado, apresenta as maiores altitudes da área; ii) morfodomínio 2, que constitui uma área dissecada relacionada aos pelitos do Grupo Areado; iii) morfodomínio 3, representado por superfícies de erosão associadas às rochas do Grupo Bambui e Pré-Bambuí, sendo sobrepostas por sedimentos terciários/quaternários, onde se encontram as lagoas; iv) morfodomínio 4, constitui vales em calha que contêm as principais drenagens da região (rios da Prata e Paracatu) segundo um padrão meandrante, com feição geomorfológica fluvial de rios underfit. Esses vales cortam a superfície de aplainamento (morfodomínio 3) que contêm sedimentos pleistocênicos, caracterizando o morfodomínio mais recente.

Important erosive processes that took place after the Cretaceous Era were responsible for the evolution of the landscape in the João Pinheiro region where spongillite deposits occur. The progression of these erosive processes on the carbonate rocks led to the development of negative karstic features where the ponds present formed the spongillite deposits. Based on field studies and analysis of multispectral images, four geomorphological domains were identified: i) domain 1, represented by a plateau related to sandstones from the Areado Group that present the highest altitudes in the area; ii) domain 2, that constitutes a desiccated area related to pelites from the Areado Group; iii) domain 3, comprising a karstic planation surface associated with carbonate rocks from the Bambui Group and Pré-Bambuí unit covered by Cenozoic sediments where the ponds occur; iv) domain 4, composed of gutter shaped valleys enclosing meandering of underfit streams (of the Prata and Paracatu rivers). These valleys cut through the karstic planation surface (domain 3) where Pleistocene sediments occur and characterize the more recent morphological domain.

Na região de Lagoa Dourada, inserida no Cinturão Mineiro, ocorrem granitóides paleoproterozóicos, que intrudem seqüências supracrustais arqueanas do greenstone belt Rio das Velhas. Os granitóides são cortados por rochas máficas anfibolitizadas, que portam xenólitos de granulitos. Trata-se de granulitos máficos caracterizados pela textura granoblástica e pela paragênese ortopiroxênio-clinopiroxênio-anfibólio-plagioclásio. Como fases secundárias, registram-se actinolita, cummingtonita, carbonato, epídoto, granada e quartzo. Determinações geotermométricas baseadas nos pares minerais ortopiroxênio-clinopiroxênio e anfibólio-plagioclásio produziram valores de temperatura entre 700 e 853ºC. As fases secundárias são produtos de um processo metamórfi co posterior.

Paleoproterozoic granitoids intruding the Archean greenstone belt of Rio das Velhas are found in the region of Lagoa Dourada, which belongs to the Mineiro Belt. The granitoids are cut by amphibolitized mafi c rocks which contain xenoliths of granulite facies rocks. The rocks are mafi c granulites, characterized by their granoblastic texture and by parageneses orthopyroxene-clinopyroxene-amphibole-plagioclase. As secondary minerals, actinolite, carbonate, epidote, cummingtonite, garnet and quartz can be found. Geothermometric determinations based on the mineral pairs orthopyroxene-clinopyroxene and amphibole-plagioclase yielded temperature values between 700ºC and 853ºC. The secondary mineral phases are interpreted as a result of a younger metamorphic event.

Esse trabalho apresenta as principais características mineralógicas, físicas e geoquímicas dos lutitos diatomáceos do Membro Villingota da Formação Tosagua, localizada na bacia Progreso no sudoeste do litoral do Equador, visando à sua utilização como matéria-prima na elaboração de compostos cerâmicos mediante ativação alcalina. Os pelitos estudados do Membro Villingota apresentam uma complexa mistura que se caracteriza pela composição química, na qual predominam sílica, carbonato e alumina, e por sua variada fauna de microfósseis, composta de diatomáceas, radiolários, espículas e foraminíferos. A ativação alcalina dessa mistura natural possibilitou a fabricação de geopolímeros, considerados materiais inorgânicos que podem substituir as argamassas e produtos minerais.

This work describes the main mineralogical, physical and geochemical characteristics of the diatom lutites of the Villingota Member of the Tosagua Formation, located in the Progreso Basin in the Southwest of the Equatorian coast, with the view of using them as raw materials in the ceramic industry by means of alkaline activation. The studied pelites of the Villingota Member are composed of a complex mixture characterized by their chemical composition with predominance of silica, carbonate, and alumina, as well as by their varied microfossil fauna that includes diatoms, radiolarians, spicules and foraminifers. The alkaline activation of this natural mixture turned possible the manufacture of geopolymers, which are inorganic materials that can substitute binders and mineral products.

Mineral characterization consisted on the study of 458diamond samples representative of gem-grade and industrialgrade varieties,obtained from alluvial (placer) diamond exploration located in the Icabaru and Uaiparu Rivers, Santa Elena de Uairén. Mineral analyseswere predominantly focused on physical properties and average weight (0.2 and 1.0ct). Optical microscopy was used to study surface sections of diamonds andmorphological characterization which resulted in the following. In relation tocolor, distribution percentages were colorless (37%), yellow (20.5%), brown(19%), green (9,5%), black (3%), green lattice points (7.5%), and brown latticepoints (3.5%). Also, a polycrystalline variety known as carbonado, orblack diamond, was studied. Some surface shapes such as trigons, quadrilateral,block and film growth, groove and hillocks were determined through ScanningElectron Microscopy (SEM) and Energy Dispersive Spectrometer technique (EDS).Morphological evolution could be established from the octahedral primitivethrough dissolution phenomena for (111)+(110), (111)+{hkl} facets having rhombicdodecahedron {hkl} and hexaoctahedron {110} habits. Chemical composition datawere collected through Infrared Absorption Spectroscopy (FTIR), and diamondtypes were determined Ib with low nitrogen concentration, IaA, IaB and IaAbdiamonds with high, average and low nitrogen concentration and IIa diamondswith no nitrogen concentration. Inclusions of olivine, ilmenite and garnet onthe crystal surface were detected by micro-Raman spectroscopy.

La caracterizaciónmineralógica consistió en el estudio de 458 cristales de diamantes entre lasvariedades gemológica e industrial, provenientes de la región de Santa Elena deUairén, específicamente de los placeres aluvionales localizados en los ríosIcabarú y Uaiparú. En este trabajo se realizaron análisis mineralógicos dondelas muestras fueron estudiadas a partir de las propiedades físicas, el pesopromedio de los cristales fue entre 0,2 y 1,0 quilates. Utilizando análisis demicroscopia óptica se estudiaron las secciones superficiales, permitiendo lacaracterización morfológica. En relación al color los porcentajes dedistribución son de 37% incoloros, 20,5% amarillos, 19% marrones, 9,5% verdes,3% negros, 7,5% con capas verdes y 3,5% capas castañas, también se consiguiódiferenciar la variedad policristalina de aspecto negruzco, denominadacarbonado. A partir de análisis de microscopía electrónica de barrido, aplicandola técnica Espectroscopía de Energía Dispersiva (EDS) se consiguió reconocerfiguras superficiales como trigons, cuadrons, crecimiento enbloque, crecimiento laminar, estrías, surcos y colinas que permitieronestablecer la evolución morfológica, partiendo del octaedro primitivo y pasandopor fenómenos de disolución originando formas transicionales (111)+(110),(111)+{hkl}, proporcionando hábitos rombododecaedricos {110} y hexaoctaedricos{hkl}. Con análisis de espectroscopía de absorción en el infrarrojo (FTIR) seobtuvieron datos de la composición química que permitieron determinar los tiposde diamante Ib, IaA, IaB , IaAB y IIa. Mediante espectroscopía micro- Raman seidentificaron inclusiones de olivino, ilmenita y granada, posicionadassuperficialmente en los cristales.

A origem dos diamantes da Serra do Espinhaço na região de Diamantina, Minas Gerais e na Chapada Diamantina, na região de Lençóis, Bahia, permanece incerta apesar das inúmeras pesquisas desenvolvidas, ao longo das últimas décadas. A ausência de minerais satélites típicos em ambos os distritos, torna incerta a possibilidade de fonte kimberlítica para os diamantes. Na região de Diamantina registra-se, desde meados do século XVIII, a ocorrência de uma rocha metamórfica, composta por martita, sericita e turmalina, denominada filito hematítico e considerada por alguns pesquisadores como uma provável fonte dos diamantes. Rochas similares foram encontradas na região de Lençóis e submetidas a estudos petrográficos tendo a concentração de minerais pesados sido investigada por microscopia eletrônica de varredura (MEV). As análises petrográficas permitiram determinar uma origem ígnea para as rochas e as análises de MEV mostraram a ocorrência de microdiamantes. Estudos geocronológicos com a técnica Ar/Ar em muscovitas revelaram idades de 1515 ±3 m.a. que são correlacionáveis às idades de 1710 ±12 m.a., obtidas pelo método U-Pb, em zircões dos filitos hematíticos. Ambos litotipos apresentam composições química e mineralógica idênticas o que permite concluir que os filitos hematíticos tiveram como protólito as rochas intrusivas. Essa descoberta inédita de microdiamantes nas rochas intrusivas descortina a possibilidade de adoção de novos modelos prospectivos para mineralizações de diamantes em terrenos do Proterozóico brasileiro.

The origin of diamonds from Serra do Espinhaço in Diamantina region (State of Minas Gerais) and in Chapada Diamantina, Lençóis region (State of Bahia) remains uncertain, even taking into account the ample research carried out during the last decades. The lack of typical satellite minerals in both districts makes a kimberlitic source for these diamonds uncertain. In mid 18th century the occurrence of a metamorphosed igneous rock composed of martite, sericite and tourmaline was described in Diamantina region and named hematitic phyllite, considered by some researchers as a possible diamond source. Similar rocks were found in Lençóis and examined petrographically and their heavy mineral concentration was investigated by means of scanning electron microscopy (SEM). Petrographic analyses indicated an igneous origin for these rocks and SEM analyses showed the discovery of microdiamonds. Geochronological studies using the Ar/Ar technique in muscovites yielded minimum ages of 1515 ± 3 Ma, which may correlate with 1710 ± 12 Ma from U-Pb method in igneous zircons from the hematitic phyllites. Both rock types also have the same mineral and chemical composition which leads to the conclusion that the intrusive rocks were protolith of the hematitic phyllites. This first discovery of microdiamonds in intrusive rocks opens the possibility of new investigation models for diamond mineralization in Brazilian Proterozoic terrains.

Uma cultura mixta e uma linhagem bacteriana pura foram isoladas de um bioreator para tratamento de tiocianato. As culturas removeram 5mM de tiocianato do meio em 36 horas. A cultura mixta foi capaz de tolerar concentrações superiores a 60mM. A eficiência da degradação de tiocianato diminuiu quando as células foram imobilizadas.

A mixed culture and a pure bacterial strain (BMV8) were isolated from a bioreactor for thiocyanate treatment. Both cultures removed 5 mM of thiocyanate from the medium in 36 hours. The mixed culture was able to tolerate concentrations up to 60 mM. The efficiency of thiocyanate degradation decreased when the cells were immobilized.

Nesse trabalho descrevemos um protocolo otimizado para extração simultânea de DNA e RNA de solo. O tratamento das amostras de solo com etanol e posterior agitação com partículas foi uma estratégia bem sucedida para lise das células sem degradação significativa dos ácidos nucléicos, resultando em bom rendimento de DNA e RNA íntegros. O RNA transcrito pode ser amplificado com iniciadores com alvo no fragmento do gene da glutamina sintetase (glnA). Os fragmentos 16S rDNA, tanto do DNA como do cDNA, foram amplificados e analisados por DGGE. O método foi aplicado para amostras de solo e rizosfera (morango e canola). Dois outros protocolos para extração de ácidos nucléicos de solo foram aplicados para o mesmo lote de amostras, de forma a comparar os métodos quanto à eficiência e reprodutibilidade. Os perfis de DGGE mostraram não haver diferença relevante nos padrões obtidos. O método descrito é apropriado para o processamento rápido de muitas amostras e, conseqüentemente, adequado para estudos ecológicos.

In this work we report an optimized protocol for simultaneous extraction of DNA and RNA from soil matrices. Treatment of soil matrices with ethanol followed by bead-beating worked as a successful strategy to lyse the cells without considerable degradation of nucleic acids, resulting in DNA and RNA of good yield and integrity. The reverse transcribed RNA could be amplified with primers targeting a glutamine synthetase (glnA) gene fragment. From both DNA and cDNA, 16S rDNA fragments were amplified and analyzed by Denaturing Gradient Gel Electrophoresis (DGGE). The method was applied to soil and rhizosphere (strawberry and oilseed rape) samples. Two other protocols for the extraction of nucleic acids from soil were applied to the same set of samples in order to compare the methods in terms of efficiency and reproducibility. The DGGE profiles indicated no relevant differences between the patterns obtained. The method described here is suitable for rapid processing of many samples and therefore appropriate for ecological studies.

Quatro linhagens de Rhodotorula mucilaginosa e uma linhagem padrão dessa mesma espécie foram investigadas quanto a habilidade de acumular íons de prata livres (Ag+) e complexados [Ag (CN)2-], através de processos dependentes e independentes do metabolismo. A habilidade de acumular Ag+ foi observada em ambas as células, vivas e mortas. Contudo, o acúmulo de Ag (CN)2- foi um processo estritamente dependente de energia. Durante os estudos que avaliaram a dependência de uma fonte energética para o acumulo de íons de prata livres (Ag+) foi observado que a adição de glicose resultou na diminuição do acúmulo de Ag+ por três linhagens (UFMG -- Y02, 27 and 35). Ao passo que as linhagens CBS 316 e UFMG -- Y01 apresentaram aumento do acúmulo desse metal. A analise dos resultados de biossorção através do modelo de Langmuir, sugerem que a linhagem UFMG -- Y27 possui a maior capacidade de acúmulo de prata (carga). Enquanto que a linhagem padrão CBS 316 apresentou a menor capacidade de carga e a maior afinidade por ions de prata. Analises de infra vermelho da biomassa fúngica, com e sem prata, mostraram que os grupamentos C=O foram os principais sítios de ligação desse metal pela linhagem UFMG -- Y27.

Five strains of Rhodotorula mucilaginosa were tested for the ability to accumulate free and complexed silver ions by metabolism-dependent and -independent processes. The ability to take up Ag+ was observed in both live and dead biomass, whereas silver dicyanide [Ag (CN)2-] uptake was strictly glucose dependent. In contrast to Ag (CN)2-, glucose addition inhibited by 16 to 25% the Ag+ uptake rate of living UFMG - Y02, Y27, and Y35 cells, while strains CBS 316 and UFMG-Y01 showed an improved uptake rate of about 115% and 13%, respectively. The Langmuir sorption model was used to evaluate the silver sorption capability of the R. mucilaginosa strains. The calculated q max value suggested that R. mucilaginosa strains UFMG-Y27 had the highest loading capacity. The type strain CBS 316 had the lowest q max but showed the highest affinity for silver ions. The results provided by the Fourier Transform Infra Red analysis (FTIR) suggest that C=O groups represent the main reactive site for silver uptake by the strain UFMG-Y27.