121 |
Perfil químico de Glandularia selloi (Spreng.) Tronc. (Verbenaceae) de ocorrência no Rio Grande do SulComerlato, Luana Christine January 2014 (has links)
O gênero Glandularia (Verbenaceae) é constituído por cerca de 80 espécies que ocorrem em regiões subtropicais e temperadas da América do Sul e América do Norte, com uma distribuição disjunta. No Sul do Brasil, encontra-se a espécie Glandularia selloi (Spreng.) Tronc., que não apresenta utilização medicinal descrita na literatura assim como não há relatos de estudos sobre a sua composição química. No entanto, a investigação do potencial químico da espécie torna-se importante como uma interessante fonte para a descoberta de novas substâncias ativas a partir de produtos naturais. O objetivo deste estudo foi investigar os principais metabólitos de Glandularia selloi nativa do Rio Grande do Sul. Para os experimentos foram coletados material na cidade de Osório, RS – Brasil, sendo posteriormente seco em temperatura ambiente, separado em raízes, caules, folhas e inflorescência, pulverizados em moinho de facas e submetido a maceração com metanol. Foram realizadas análises com CLAE-DAD, CLUE-EM visando caracterizar os extratos. Compostos obtidos através de cromatografia de coluna de sílica gel foram analisados por RMN 1H e RMN 13C. As análises permitiram identificar quatro compostos sendo eles: verbascosídeo, crisoeriol diglicosilado e diacetilado, crisoeriol diglicosilado e monoacetilado e 6-OH-β-ipolamida. Realizou-se também ensaio de citotoxicidade com extratos metanólicos de raízes, caules, folhas e inflorescência de Glandularia selloi, onde se observou efeito citotóxico em todos os extratos. / The Glandularia genus (Verbenaceae) comprises about 80 species occurring in subtropical and temperate regions of South America and North America, with a disjunct distribution. In the southern regions of Brazil, the Glandularia selloi (Spreng.) Tronc. species can be found, which has no medical uses described in literature and no reports on its chemical composition have been found either. However, investigation of the chemical potential of this species becomes important as a strategy to discover new active substances from natural products. The aim of this study was to investigate the main metabolites of a native species from Rio Grande do Sul, Glandularia selloi. Botanical samples for experiments were collected in the city of Osório, RS - Brazil, and subsequently dried separated by parts, crushed and subjected to methanol maceration. Analysis by HPLC-PDA, UPLC-MS were performed aiming to characterize the extracts. Isolated compounds obtained through column chromatography on silica gel were analyzed by 1H and 13C NMR. These analyses allowed the identification of four compounds: verbascoside, diglycosylated and diacetylated crysoeriol, diglycosylated and monoacetylated crysoeriol and 6-β-OH-hydroxyipolamiide. Further assays also were carried out to investigate the cytotoxicity of the species and it was observed that the methanolic extracts of all Glandularia selloi parts were cytotoxic species.
|
122 |
Remoção de metais da drenagem ácida de minas por precipitação química e por troca iônica com zeólita NaP1Horn, Martha Beatriz January 2015 (has links)
A mineração do carvão fóssil gera grandes volumes de rejeitos que podem ser responsáveis por graves danos ambientais, entre os quais a Drenagem Ácida de Minas (DAM) decorrente da oxidação da pirita (FeS2) na presença de água e ar. Este percolado apresenta um baixo pH, rico em íons sulfato e ferro, bem como outros metais solúveis, como alumínio, manganês e zinco. Atualmente, o tratamento mais utilizado para este efluente é a precipitação/neutralização. Contudo, este processo muitas vezes é ineficiente para a remoção de manganês. Assim, o objetivo geral deste trabalho foi realizar o tratamento da Drenagem Ácida de Minas, visando à remoção de metais, com foco especial na remoção do íon manganês, utilizando as etapas de precipitação e, após, a troca iônica com zeólitas sintetizadas a partir de cinzas leves de carvão. A metodologia deste trabalho compreendeu duas etapas: 1°) síntese da zeólita NaP1, a partir de cinzas leves de carvão de Candiota por processo hidrotérmico e sua caracterização, 2°) caracterização da DAM, seguido de tratamento por precipitação/neutralização, e por troca iônica - zeólitas. O estudo foi aplicado para uma DAM proveniente da região carbonífera de Santa Catarina. Os resultados dos testes de caracterização do produto da síntese demonstraram a formação da zéolita NaP1, com CTC de 2,3 meq g-1. A DAM apresentou resultados típicos, com pH baixo, elevadas concentrações de Fe e sulfato e valores de manganês de 45,15 mg L-1. Os resultados do tratamento inicial mostraram que o tratamento do efluente por precipitação/neutralização, em pH 6,0, com Ca(OH)2, promove a remoção total de Al, Fe e Zn, contudo a concentração de manganês ainda fica em 28,24 mg L-1. No tratamento por troca iônica, utilizou-se a zeólita NaP1 para a remoção do manganês restante no efluente. O tempo de contato foi de 30 min, a razão S/L de 10 g L-1. O emprego da zeólita promoveu a remoção total do manganês da DAM. O mecanismo de remoção de Mn2+ ocorre por troca iônica na faixa de pH neutra e por precipitação superficial em valores de pH acima de 8,5. Em condições de laboratório, o custo do tratamento com zeólitas foi o dobro do tratamento por precipitação/neutralização. O tratamento com a utilização de zeólitas, seria uma alternativa visando a diminuição do consumo de cal hidratada com elevação do pH e remoção do Mn residual. / The mining of fossil coal generates large volumes of waste that may be responsible for serious environmental damage, including the acid mine drainage (AMD) resulting from oxidation of pyrite (FeS2) in the presence of water and air. This percolated has a low pH, rich in sulphate ions and iron as well as other soluble metals such as aluminum, manganese and zinc. Nowadays the most common treatment for this wastewater, is precipitation/neutralization. However, this process is inefficient for the removal of manganese. Thus the general aim this study was the treatment of acid mine drainage, aiming the removing metals, with special focus on removal of manganese ion, using the steps of precipitation and after the ion exchange with synthesized zeolites from fly ash coal. The methodology of this work included two steps: 1°) synthesis zeolite NAP1 from fly ash coal of Candiota by hydrothermal process and their characterization, 2°) characterization of AMD treatment followed by precipitation/neutralization and ion exchange-zeolite. The study was applied for a AMD from the coalfield of Santa Catarina. The results of the characterization tests of the synthesis product showed the formation of the zeolite NaP1, CEC from 2.3 meq g-1. The AMD showed typical results with low pH, high concentration of Fe and sulfate and manganese values 45.15 mg L-1. The results of the initial treatment from precipitation/neutralization showed that treatment of effluent by precipitation/neutralization at pH 6.0 with Ca(OH)2 promotes complete removal of Al, Fe e Zn, however the concentration is still in the manganese 28.24mg L-1. In the treatment by ion exchange, the zeolite NaP1 was used for the remaining manganese removal in wastewater. The contact time was 30 min, the ratio S/L 10 g L-1. The use of zeolite promoted the complete removal of manganese from AMD. The manganese removal by ion exchange mechanism occurs in the neutral range and surface precipitation in values above 8.5. In laboratory conditions, the cost of treatment with zeolite was double treatment by precipitation/neutralization. The treatment with use of zeolite would be an alternative aiming to decrease consumption of hydrated lime with increased pH and removing the residual Mn.
|
123 |
Remoção de metais da drenagem ácida de minas por precipitação química e por troca iônica com zeólita NaP1Horn, Martha Beatriz January 2015 (has links)
A mineração do carvão fóssil gera grandes volumes de rejeitos que podem ser responsáveis por graves danos ambientais, entre os quais a Drenagem Ácida de Minas (DAM) decorrente da oxidação da pirita (FeS2) na presença de água e ar. Este percolado apresenta um baixo pH, rico em íons sulfato e ferro, bem como outros metais solúveis, como alumínio, manganês e zinco. Atualmente, o tratamento mais utilizado para este efluente é a precipitação/neutralização. Contudo, este processo muitas vezes é ineficiente para a remoção de manganês. Assim, o objetivo geral deste trabalho foi realizar o tratamento da Drenagem Ácida de Minas, visando à remoção de metais, com foco especial na remoção do íon manganês, utilizando as etapas de precipitação e, após, a troca iônica com zeólitas sintetizadas a partir de cinzas leves de carvão. A metodologia deste trabalho compreendeu duas etapas: 1°) síntese da zeólita NaP1, a partir de cinzas leves de carvão de Candiota por processo hidrotérmico e sua caracterização, 2°) caracterização da DAM, seguido de tratamento por precipitação/neutralização, e por troca iônica - zeólitas. O estudo foi aplicado para uma DAM proveniente da região carbonífera de Santa Catarina. Os resultados dos testes de caracterização do produto da síntese demonstraram a formação da zéolita NaP1, com CTC de 2,3 meq g-1. A DAM apresentou resultados típicos, com pH baixo, elevadas concentrações de Fe e sulfato e valores de manganês de 45,15 mg L-1. Os resultados do tratamento inicial mostraram que o tratamento do efluente por precipitação/neutralização, em pH 6,0, com Ca(OH)2, promove a remoção total de Al, Fe e Zn, contudo a concentração de manganês ainda fica em 28,24 mg L-1. No tratamento por troca iônica, utilizou-se a zeólita NaP1 para a remoção do manganês restante no efluente. O tempo de contato foi de 30 min, a razão S/L de 10 g L-1. O emprego da zeólita promoveu a remoção total do manganês da DAM. O mecanismo de remoção de Mn2+ ocorre por troca iônica na faixa de pH neutra e por precipitação superficial em valores de pH acima de 8,5. Em condições de laboratório, o custo do tratamento com zeólitas foi o dobro do tratamento por precipitação/neutralização. O tratamento com a utilização de zeólitas, seria uma alternativa visando a diminuição do consumo de cal hidratada com elevação do pH e remoção do Mn residual. / The mining of fossil coal generates large volumes of waste that may be responsible for serious environmental damage, including the acid mine drainage (AMD) resulting from oxidation of pyrite (FeS2) in the presence of water and air. This percolated has a low pH, rich in sulphate ions and iron as well as other soluble metals such as aluminum, manganese and zinc. Nowadays the most common treatment for this wastewater, is precipitation/neutralization. However, this process is inefficient for the removal of manganese. Thus the general aim this study was the treatment of acid mine drainage, aiming the removing metals, with special focus on removal of manganese ion, using the steps of precipitation and after the ion exchange with synthesized zeolites from fly ash coal. The methodology of this work included two steps: 1°) synthesis zeolite NAP1 from fly ash coal of Candiota by hydrothermal process and their characterization, 2°) characterization of AMD treatment followed by precipitation/neutralization and ion exchange-zeolite. The study was applied for a AMD from the coalfield of Santa Catarina. The results of the characterization tests of the synthesis product showed the formation of the zeolite NaP1, CEC from 2.3 meq g-1. The AMD showed typical results with low pH, high concentration of Fe and sulfate and manganese values 45.15 mg L-1. The results of the initial treatment from precipitation/neutralization showed that treatment of effluent by precipitation/neutralization at pH 6.0 with Ca(OH)2 promotes complete removal of Al, Fe e Zn, however the concentration is still in the manganese 28.24mg L-1. In the treatment by ion exchange, the zeolite NaP1 was used for the remaining manganese removal in wastewater. The contact time was 30 min, the ratio S/L 10 g L-1. The use of zeolite promoted the complete removal of manganese from AMD. The manganese removal by ion exchange mechanism occurs in the neutral range and surface precipitation in values above 8.5. In laboratory conditions, the cost of treatment with zeolite was double treatment by precipitation/neutralization. The treatment with use of zeolite would be an alternative aiming to decrease consumption of hydrated lime with increased pH and removing the residual Mn.
|
124 |
New data on hemihedrite from ArizonaLafuente, B., Downs, R. T., Origlieri, M. J., Domanik, K. J., Gibbs, R. B., Rumsey, M. S. 01 August 2017 (has links)
Hemihedrite from the Florence Lead-Silver mine in Pinal County, Arizona, USA was first described and assigned the ideal chemical formula Pb10Zn(CrO4)(6)(SiO4)(2)F-2, based upon a variety of chemical and crystal-structure analyses. The primary methods used to determine the fluorine content for hemihedrite were colorimetry, which resulted in values of F that were too high and inconsistent with the structural data, and infrared (IR) spectroscopic analysis that failed to detect OH or H2O. Our reinvestigation using electron microprobe analysis of the type material, and additional samples from the type locality, the Rat Tail claim, Arizona, and Nevada, reveals the absence of fluorine, while the presence of OH is confirmed by Raman spectroscopy. These findings suggest that the colorimetric determination of fluorine in the original description of hemihedrite probably misidentified F due to the interferences from PO4 and SO4, both found in our chemical analyses. As a consequence of these results, the study presented here proposes a redefinition of the chemical composition of hemihedrite to the ideal chemical formula Pb10Zn(CrO4)(6)(SiO4)(2)(OH)(2). Hemihedrite is isotypic with iranite with substitution of Zn for Cu, and raygrantite with substitution of Cr for S. Structural data from a sample from the Rat Tail claim, Arizona, indicate that hemihedrite is triclinic in space group P (1) over bar, a = 9.4891(7), b = 11.4242(8), c = 10.8155(7) angstrom, alpha = 120.368(2)degrees, ss = 92.017(3)degrees, gamma = 55.857(2)degrees, V = 784.88(9) angstrom(3), Z = 1, consistent with previous investigations. The structure was refined from single-crystal X-ray diffraction data to R-1 = 0.022 for 5705 unique observed reflections, and the ideal chemical formula Pb10Zn(CrO4)(6)(SiO4)(2)(OH)(2) was assumed during the refinement. Electron microprobe analyses of this sample yielded the empirical chemical formula Pb-10.05(Zn0.91Mg0.02)(Sigma) (= 0.93) (Cr5.98S0.01P0.01)(Sigma = 6.00) Si1.97O34 H-2.16 based on 34 O atoms and six (Cr + S + P) per unit cell.
|
125 |
Hydroxycalciomicrolite, Ca1.5Ta2O6(OH), a new member of the microlite group from Volta Grande pegmatite, Nazareno, Minas Gerais, BrazilAndrade, M. B., Yang, H., Atencio, D., Downs, R. T., Chukanov, N. V., Lemée-Cailleau, M. H., Persiano, A. I. C., Goeta, A. E., Ellena, J. 01 May 2017 (has links)
Hydroxycalciomicrolite, Ca1.5Ta2O6(OH) is a new microlite-group mineral found in the Volta Grande pegmatite, Nazareno, Minas Gerais, Brazil. It occurs as isolated octahedral and as a combination of octahedral and rhombic dodecahedral crystals, up to 1.5 mm in size. The crystals are yellow and translucent, with a white streak and vitreous to resinous lustre. The mineral is brittle, with a Mohs hardness of 56. Cleavage is not observed and fracture is conchoidal. The calculated density is 6.176 g cm(3). Hydroxycalciomicrolite is isotropic, n(calc). = 2.010. The infrared and Raman spectra exhibit bands due to OH stretching vibrations. The chemical composition determined from electron microprobe analysis (n = 13) is (wt.%): Na2O 0.36(8), CaO 15.64(13), SnO2 0.26(3), Nb2O5 2.82(30), Ta2O5 78.39(22), MnO 0.12(2), F 0.72(12) and H2O 1.30 (from the crystal structure data), O = F -0.30, total 99.31(32), yielding an empirical formula, (Ca1.48Na0.06Mn0.01)(Sigma 1.55)(Ta1.88Nb0.11Sn0.01)S2.00O6.00[(OH)(0.76)F0.20O0.04]. Hydroxycalciomicrolite is cubic, with unit-cell parameters a = 10.4205(1) angstrom, V = 1131.53(2) angstrom(3) and Z = 8. It represents a pyrochlore supergroup, microlite-group mineral exhibiting P4(3)32 symmetry, instead of Fd (3) over barm. The reduction in symmetry is due to long-range ordering of Ca and vacancies on the A sites. This is the first example of such ordering in a natural pyrochlore, although it is known from synthetic compounds. This result is promising because it suggests that other species with P4(3)32 or lower-symmetry space group can be discovered and characterized.
|
126 |
Etude des mécanismes d'oxydation des composés terpéniques par le radical OHRio, Caroline 18 December 2009 (has links)
Ce travail a eu pour objectif d’étudier la formation des Aérosols Organiques Secondaires (AOS) à partir de réactions de composés monoterpèniques (alpha-pinene, béta-pinene, d-limonene et gamma-terpinene) avec les radicaux OH. Il s’agissait dans un premier temps de se focaliser sur la première étape d’oxydation qui consiste en l’addition du radical OH sur la double liaison ou en l’abstraction d’un atome d’hydrogène avec formation de H2O. Le rapport de branchement entre l’addition et l’abstraction a donc été mesuré à différentes pressions. Ces réactions ont été étudiées à pression atmosphérique en utilisant la photolyse laser associée à la détection par absorption UV et à basse pression en utilisant un réacteur à écoulement couplé à un spectromètre de masse à temps de vol. Dans un second temps les produits d’oxydation formés à pression atmosphérique, qui composent les AOS, ont été piégés puis analysés par chromatographie gazeuse couplée à la spectrométrie de masse. / This aim of this work was to study the formation of secondary organic aerosols (SOA) from reactions of monoterpene compounds (alpha-pinene, beta-pinene, d-limonene, and gamma-terpinene) with OH radicals. In a first time, we focused on the first oxidation steps which may occur by two different reaction pathways: OH addition on the double bond and abstraction of a hydrogen atom (with formation of H2O). The branching ratio between addition and abstraction has been measured at different pressures. These reactions were studied at atmospheric pressure using laser photolysis coupled with detection by UV absorption and at low pressure using a fast flow reactor coupled to a time of flight mass spectrometer. In a second time, the oxidation products formed at atmospheric pressure, which composed the SOA, were trapped and analyzed by gas chromatography coupled to mass spectrometry.
|
127 |
Beyond Suzie Wong? An Analysis of Sandra Oh’s Portrayal in Grey’s AnatomyJones, Norma 08 1900 (has links)
In my study, I examine if and how Sandra Oh’s portrayal of Dr. Cristina Yang in Grey’s Anatomy, a primetime network drama, reifies or resists U.S. mediated stereotypes of Asian American females. I situate my intercultural study in an interpretive paradigm because I am want to explore how the evolving characteristics of existing the Asian American female mediated stereotype as they influence Asian American female identity. Additionally, I trace the historical development of Asian and Asian American stereotypes yellow peril to the model minority; and from Dragon Lady, Lotus Blossom, Geisha, and Suzie Wong. From my textual analysis, I suggest that when portrayals simultaneously reify and resist characteristics of existing Asian American stereotypes, they may help to breakdown perceived binaries of existing Asian and Asian American stereotypes.
|
128 |
An experimental study of the global and local flame features created by thermoacoustic instabilityZhang, Jianan 01 August 2017 (has links)
The current research focuses on the thermoacoustic instability of lean premixed combustion, which is a promising technique to inhibit Nitrogen Oxides (NOx) emission. Thermoacoustic instability describes the condition that the pressure oscillation is unusually high in the combustion device. It results from the coupling between pressure fluctuation and heat release oscillation, which experiences significant temporal and spatial variations. These variations are closely related to the flame shape deformation and critical in determining the trend of the global instability. Therefore, the current study aims to examine both the global and local flame features created by thermoacoustic instability.
The first part of the work is studying the unstable flame induced by artificial acoustic perturbation. The particular focus is on the global and local heat release rate oscillation. In the experiment, the global heat release rate oscillation was indicated by the hydroxyl (OH*) chemiluminescence captured with a photomultiplier tube (PMT). On the other hand, the flame shape and the local mean heat release rate were examined with flame surface density (FSD), which was calculated with the images captured with the planar laser-induced fluorescence of the hydroxide radical (OH-PLIF) method. The main analysis methods used in the current research are Rayleigh criterion and proper orthogonal decomposition (POD), which can efficiently capture the dominant oscillation mode of the flame.
The acoustic perturbation study first examined the effect of pressure variation (0.1 - 0.4 MPa) on the flame response to the acoustic perturbation. Results show that the elevated pressure intensifies the fundamental mode of heat release oscillation when the heat release oscillation is in phase with the pressure fluctuation; otherwise, the fundamental oscillation tends to be inhibited. The pressure affects both the strength and the distribution of the local fundamental and the first harmonic oscillations. Furthermore, the effect of the pressure on the distribution is larger than that on the strength.
The study also investigated the role of Strouhal numbers in characterizing the flame oscillation induced by acoustic perturbation. Results show that the Strouhal number can characterize the changing trend of the oscillation amplitude, whereas the oscillation phase-delay is less dependent on the Strouhal number. The local analysis reveals that the nonlinear flame behavior results from the flame rollup induced by acoustic perturbation. Furthermore, the reconstruction of the global heat release shows that the cancellation of out-of-phase local oscillations can cause a low-level global oscillation. Results also demonstrate that the local heat release oscillation contains intense harmonic oscillations, which are closely associated with the flame rollup. However, the harmonic oscillation is less likely the main reason causing nonlinear flame behavior.
Besides the study with acoustic perturbation, the current study also conducted experimental and modeling studies on the self-excited thermoacoustic instability. The particular focus is examining the effects of hydrogen addition on the instability trend. Results demonstrate that the hydrogen concentration can affect both the oscillation frequency and amplitude. Pressure analysis shows that the low-frequency mode is triggered when the hydrogen concentration is low, whereas a high hydrogen concentration tends to excite a high-frequency mode. Moreover, the frequency tends to increase with an increasing hydrogen concentration. Modeling results illustrate that the change of the oscillation mode, which is determined by the turbulent flame speed, is mainly affected by the delay time between the heat release oscillation and the velocity fluctuation. The modeling work shows that the one-dimensional model is not very efficient in capture the instability trend of the high-frequency mode. It may result from the lack of the knowledge of the mechanism of acoustic damping and flame dynamics.
|
129 |
A-Bu-GE: A Composition for Organ and PercussionKim, Chol-Ho 12 1900 (has links)
Keyphrases describe a document in a coherent and simple way, giving the prospective reader a way to quickly determine whether the document satisfies their information needs. The pervasion of huge amount of information on Web, with only a small amount of documents have keyphrases extracted, there is a definite need to discover automatic keyphrase extraction systems. Typically, a document written by human develops around one or more general concepts or sub-concepts. These concepts or sub-concepts should be structured and semantically related with each other, so that they can form the meaningful representation of a document. Considering the fact, the phrases or concepts in a document are related to each other, a new approach for keyphrase extraction is introduced that exploits the semantic relations in the document. For measuring the semantic relations between concepts or sub-concepts in the document, I present a comprehensive study aimed at using collaboratively constructed semantic resources like Wikipedia and its link structure. In particular, I introduce a graph-based keyphrase extraction system that exploits the semantic relations in the document and features such as term frequency. I evaluated the proposed system using novel measures and the results obtained compare favorably with previously published results on established benchmarks.
|
130 |
Laser investigations on a plasma assisted flameDel Cont-Bernard, Davide 09 1900 (has links)
Sustainable and low emission combustion requires new combustion paradigms and solutions to increase efficiency, comply with more stringent regulations on pollutants, and cope with the varying qualities of renewable fuels. Plasma Assisted Combustion (PAC) could be one of the tools to achieve these goals in practical combustion systems. Previous studies showed that PAC can be used in a variety of applications: to improve ignition in difficult environments, to extend the operating range of burners to leaner conditions, to contrast thermoacoustic instability, to allow flame-holding in extreme conditions, and more. While applications keep being proposed, there are efforts to model and understand the coupling between flames and plasma discharges. This work contributes to the unraveling of the action of plasma discharges on flames by performing a number of investigations on a simple PAC burner. Trends and temporal evolution of key chemical species and electric fields are measured during plasma actuation of the flame. Experimental datasets resulting from this work are meant to be used in cross-validating numerical simulations. The considered PAC burner generates a lean methane-air stagnation flame, across which discharges are applied, developing partially in the fresh and partially in the burned gases. Time-resolved 2D imaging of atomic hydrogen and oxygen is obtained by using two-photon absorption planar laser induced fluorescence (TALIF) while OH and CH radicals are measured by using planar laser induced fluorescence (PLIF). To measure the electric field, the Electric Field Induced Second Harmonic generation (EFISH) technique is used. A novel deconvolution-like post-processing procedure is proposed and used to calibrate the measurements and improve the spatial resolution, overcoming limitations and distortions typical of EFISH measurements. Presented results quantify the effect of the plasma actuation on the flame and lend themselves to the validation of numerical models.
|
Page generated in 0.0303 seconds