5,320 research outputs found
Relativistic viscous hydrodynamics and AdS/CFT correspondence at finite temperature
No full textBaier R. Relativistic viscous hydrodynamics and AdS/CFT correspondence at finite temperature. In: Bartels J, Borras K, Gustafson G, et al., eds. Proceedings of the 38th International Symposium on Multiparticle dynamics ISMD08. Hamburg: Deutsches Elektronen-Synchrotron; 2008: 130-134
Proceedings of the 38th International Symposium on Multiparticle Dynamics (ISMD08)
No full textBartels J,, Borras K,, Gustafson G,, et al., eds. Proceedings of the 38th International Symposium on Multiparticle Dynamics (ISMD08).; 2008
Extração de cafeína de borras de café utilizando soluções aquosas de líquidos iónicos
No full textMestrado em Engenharia QuímicaThe main objective of this work consists on the development of a more benign and efficient technique for the extraction of added-value compounds from biomass. In particular, the use of ionic liquids (ILs) for the extraction of caffeine from spent coffee was investigated. This compound display important properties with relevance in food, pharmaceutical, cosmetic and agrochemical industries. Spent coffee grounds (SCG) are a waste product without commercial value, being thus a raw material with virtually no cost and with a huge potential of value-added compounds able to be extracted. To this end, solid-liquid extractions from biomass were carried out using aqueous solutions of various ILs as well as mixtures of ILs and salts. As a first attempt, several protic Ils (PILs) were synthesized and characterized. These were chosen since they have unique characteristics that facilitate their recovery as well as the separation of the extracted components. The results obtained indicate that triethanolammonium acetate is the best candidate to extract caffeine. More specifically, at the concentration of 2 M, a temperature of 358 K (85°C), a solid-liquid ratio of 0,1 and 45 minutes of extraction time, it was achieved a value of extracted caffeine of 3.01% (w/w). Aqueous solutions of different aprotic ILs, with a common cholinium cation, were also investigated for the extraction of caffeine. A factorial planning was carried out in order to identify the optimum operating conditions. The optimum operating conditions for caffeine extraction with aqueous solutions of cholinium bicarbonate were obtained in the following conditions: time of 30 minutes, temperature of 323 K (50°C), solid-liquid ratio of 0.05 and LI concentration of 1.5 M, where the value of caffeine extraction obtained was of 1.85% (w/w). Mixtures of salts with hydrotropic characteristics with ILs were finally investigated for the extraction of caffeine in order to combine the properties of both classes of compounds. It has been found that the compounds containing the tosylate anion have a higher ability to extract caffeine. In addition, the LI 1-butyl-3-methylimidazolium tosylate or an equimolar mixture of sodium tosylate with 1-butyl-3-methylimidazolium chloride, lead to similar values of extracted caffeine. More specifically, for a concentration of 1M, the value obtained for the extraction of caffeine was of 3.50% (w/w), at a temperature of 348 K (75°C), extraction time of 30 minutes and solid-liquid ratio of 1:10.
In summary, this thesis describes the application of aqueous solutions of ILs foreseeing the development of more efficient and sustainable extractive processes.O principal objetivo desta dissertação recai sob o estudo de técnicas de extração alternativas de compostos de valor acrescentado a partir de biomassa, mais benignas e eficientes do que as habitualmente utilizadas. Em particular, estudou-se a utilização de soluções aquosas de líquidos iónicos (LIs) para a extração de cafeína a partir de borras de café. O interesse da extração deste composto deve-se às suas propriedades e consequente interesse pelas indústrias alimentar, farmacêutica, cosmética e agroquímica. De salientar ainda que as borras de café são um produto residual sem valor associado, constituindo uma matéria-prima praticamente sem custos e com um enorme potencial de compostos químicos de valor acrescentado passíveis de serem extraídos. Para tal, efetuaram-se extrações do tipo sólido-líquido a partir de borras de café utilizando várias soluções aquosas de LIs, assim como misturas de LIs com sais.
Começou-se pela síntese de líquidos iónicos próticos (LIPs) e sua caracterização. A utilização de LIPs prende-se com o facto de possuírem características muito singulares que facilitariam a recuperação bem como a separação dos compostos extraídos. Os resultados obtidos mostraram, que dos LIPs sintetizados, o mais promissor na extração de cafeína foi o acetato de trietanolamina. Mais concretamente, para uma concentração de 2 M, uma temperatura de 358 K (85˚C), uma razão sólido-liquido de 0,1 e um tempo de extração de 45 minutos, conseguiu-se obter uma percentagem de cafeína extraída de 3,01% (m/m).
Também se estudou a otimização da extração da cafeína de borras de café utilizando como solvente soluções aquosas de diferentes LIs apróticos, com o catião colínio em comum, em que se recorreu a um planeamento fatorial por forma a obter o ponto ótimo de extração, relativamente à temperatura, razão sólido-liquido, tempo e concentração do LI. Verificou-se que o ponto ótimo de operação para a extração de cafeína com soluções aquosas de bicarbonato de colínio ocorre para um tempo de 30 minutos, um temperatura de 323 K (50ºC), uma razão sólido-liquido de 0,05 e concentração de LI de 1,5 M, onde a extração de cafeína obtida foi de 1,85% (m/m).
Foram também testadas misturas de sais com atividade hidrotrópica com LIs apróticos, com um catião imidazólio em comum, a fim de conjugar as propriedades de ambos os compostos de forma a potenciar a extração de cafeína. Constatou-se que os compostos (sal ou LI) que contêm o anião tosilato tem capacidade de extrair uma maior percentagem de cafeina. Os valores de extração obtidos, utilizando o LI tosilato de 1-butil-3-metilimidazólio ou uma mistura equimolar de tosilato de sódio com cloreto de 1-butil-3-metilimidazólio, foram semelhantes, sendo que para a concentração de 1M a extração de cafeina foi de 3,50 % (m/m), a uma temperatura de 348 K (75ºC), tempo de 30 minutos e razão sólido-liquido de 1:10.
Em suma, esta tese descreve a aplicação de soluções aquosas LIs visando o desenvolvimento de processos extrativos mais eficientes e sustentáveis
Search for new phenomena in final states with large jet multiplicities and missing transverse momentum at s√=8 TeV proton-proton collisions using the ATLAS experiment
No full textA search is presented for new particles decaying to large numbers (7 or more) of jets, with missing transverse momentum and no isolated electrons or muons. This analysis uses 20.3 fb−1 of pp collision data at s√=8 TeV collected by the ATLAS experiment at the Large Hadron Collider. The sensitivity of the search is enhanced by considering the number of b-tagged jets and the scalar sum of masses of large-radius jets in an event. No evidence is found for physics beyond the Standard Model. The results are interpreted in the context of various simplified supersymmetry-inspired models where gluinos are pair produced, as well as an mSUGRA/CMSSM model
19 February 2015 - Professor Holger Hanselka President Karlsruhe Institute of Technology Federal Republic of Germany
No full textvisiting the CMS cavern with CMS Collaboration Deputy Spokesperson K. Borras and CMS Collaboration, Team Leader, Karlsruhe Institut fur Technologie T. Muller and signing the Guest book with CERN Director-General R. Heuer. C. Schaefer present throughout
Functional Superoxide Dismutase Mimics. Structural Characterization and Magnetic Exchange Interactions of Copper(II)-N-substituted Sulfonamide Dimer Complexes
No full textDinuclear copper(II) complexes with N-substituted sulfonamide ligands as superoxide dismutase (SOD) mimics
have been investigated. The new N-(thiazol-2-yl)toluenesulfonamide (Htz-tol) and N-(thiazol-2-yl)naphthalenesulfonamide
(Htz-naf) ligands have been prepared and structurally characterized. The complexes derived from
these ligands, [Cu2(tz-tol)4] (1) and [Cu2(tz-naf)4] (2), have been synthesized, and their crystal structure, magnetic
properties, and EPR spectra were studied in detail. In both compounds the metal centers are bridged by four
nonlinear triatomic NCN groups. The coordination geometry of the coppers in the dinuclear entity of 1 and 2 is
distorted square planar with two N-thiazole and two N-sulfonamido atoms. Magnetic susceptibility data show a
strong antiferromagnetic coupling, with -2J ) 121.3 cm-1 for compound 1 and -2J ) 104.3 cm-1 for compound
2. The EPR spectra of the polycrystalline samples of compounds 1 and 2 have been measured at the X- and
Q-band frequencies at different temperatures. Above 20 K the spectra are characteristic of S ) 1 species with
zero-field splitting parameter D ) 0.230 cm-1 for compound 1 and 0.229 cm-1 for compound 2. The EPR parameters
are discussed in terms of the known binuclear structures. The complexes exhibit high SOD activity, as shown by
the low IC50 values obtained with the xanthine/xanthine oxidase/NBT assay: 0.13 íM for compound 1; 0.17 íM
for compound
Hard diffraction at CDF
No full textRecently published and new preliminary results from the analyses of diffractive events selected with a central or a forward rapidity gap are summarized. New measurements of the ratio of dijet production in single diffractive and non-diffractive events obtained from the Roman Pot data are discussed
An investigation of e-government progress in Oman: A survey of public sector workers
No full textE-government has become increasingly pervasive in modern society and it has emerged as an effective means of delivering government services to citizens. While most early e-government efforts were concentrated on developed countries, in the recent past, it has also become popular in many developing countries. Most notably are the Middle Eastern countries that have continued to invest significantly into e-government initiatives in the last five years; the Sultanate of Oman is one such example. However, although large investments have been made since 2003 to facilitate the implementation of electronic services in the public sector in Oman, only limited progress has been made in terms of realising fully functional e-government. The aim of this paper is to identify the factors that are currently influencing the development and implementation of e-government in Oman using a quantitative survey-based empirical study in three key public service agencies in Muscat, the capital of Oman. The research identified ten different factors that were influencing the progress of the national e-government project, e-Oman, from the viewpoint of government employees. The most salient of these factors was the Omani IT workforce capability and the citizens' trust and confidence in using e-services
Influência da variedade de uva, do método de elaboração e envelhecimento sobre borras na composição química e sensorial de espumantes
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias, Programa de Pós-Graduação em Ciência dos Alimentos, Florianópolis, 2014.Dentre as diferentes técnicas de elaboração de vinhos destaca-se a elaboração de espumantes. O mercado brasileiro de vinhos espumantes tem aumentado quantitativamente e qualitativamente, sendo considerado como um dos produtos que melhor representa o potencial vinícola brasileiro. Os objetivos deste estudo foram: caracterizar o perfil volátil de espumantes elaborados pelo método tradicional com variedades clássicas e inovadoras; caracterizar a composição volátil de vinhos espumantes da variedade Moscato Giallo elaborados por três diferentes métodos: Tradicional, Charmat e Asti e avaliar a influência do tempo de envelhecimento sobre borras "sur lie" quanto às características químicas e sensoriais de espumantes elaborados com as variedades de uva Goethe, Villenave, Niágara e Chardonnay. Na caracterização do perfil volátil de espumantes elaborados pelo método tradicional foram utilizadas as variedades inovadoras híbridas e Vitis labrusca (Niágara, Moscato Embrapa, Villenave, Goethe e Manzoni Bianco) e clássicas as variedades Vitis vinifera Chardonnay, Pinot Gris, Riesling Renano, Sauvignon Blanc e Pinot Noir, as amostras ficaram 18 meses sobre as borras e após foi determinado o perfil aromático por CG-FID e CG-MS, os compostos fenólicos foram determinados por CLAE-DAD e a atividade antioxidante por espectrofotometria. Na avaliação da influência dos métodos de elaboração de espumantes na composição volátil foi utilizado a variedade Moscato Giallo, e a elaboração dos espumantes pelos métodos Asti, Clássico e Charmat. A avaliação do tempo de envelhecimento sobre borras foi realizada com 8, 16 e 24 meses em contato com as borras, as variedades Goethe, Villenave, Niágara e Chardonnay foram avaliadas, quanto aos parâmetros enológicos clássicos, atividade antioxidante, polifenóis totais, absorbância a 420 nm, orto-difenóis, flavanóis totais e análise sensorial. Na avaliação dos espumantes elaborados com as variedades clássicas e inovadoras, o composto fenólico com maior concentração foi o tirosol, o perfil aromático 25 compostos foram determinados sendo que o acetato de isoamila apresentou altas concentrações em todas as amostras de espumantes, particularmente na amostra de Moscato Embrapa. Também foram observadas elevadas concentrações de monoterpenos como linalool, nas amostras de Riesling Renano e de geraniol nas amostras de Moscato Embrapa. Nas análises estatísticas multivariadas de componentes principais e cluster dos compostos voláteis e das14variedades foi observado separação em dois grupos um com as variedades inovadoras Moscato Embrapa, Niágara e Villenave e outro com as demais variedades. Na avaliação da influência dos métodos de elaboração, os espumantes elaborados pelo método Clássico apresentaram as maiores concentrações de compostos voláteis, e os espumantes elaborados pelo método Asti apresentaram as menores concentrações. A influência do método de elaboração na composição volátil dos espumantes Moscato Giallo foi confirmada pela análise multivariada de componentes principais, a qual demonstrou boa separação entre os espumantes em três grupos distintos conforme método de elaboração utilizado. No estudo de avaliação dos tempos de envelhecimento sobre borras a avaliação sensorial mostrou que os espumantes das variedades Niágara e Goethe apresentaram melhor impressão global com menor tempo sobre borras "sur lie" e os espumantes elaborados com as variedades Villenave e Chardonnay apresentaram os melhores resultados de impressão global para as amostras com maior tempo sobre borras.Abstract : The technique of sparkling wine production is a highlighted procedure among techniques of wine production. The Brazilian market for sparkling wines has increased quanti- and qualitatively, being considered one of the products that best represents the Brazilian winery potential. The objectives of this study were to characterize the volatile profile of sparkling wines produced by the traditional method with classic and innovative varieties; to characterize the volatile composition of sparkling wines obtained from Moscato Giallo variety and prepared by three different methods: Traditional, Charmat and Asti; and to evaluate the influence of aging time on "sur lie" lees on chemical and sensorial features of sparkling wines from Goethe, Villenave, Niagara and Chardonnay grape varieties. The volatile profile of sparkling wines produced in traditional method was characterized in innovative hybrid varieties of Vitis labrusca (Niagara, Moscato Embrapa, Villenave, Goethe and Manzoni Bianco) and the classic Vitis vinifera varieties (Chardonnay, Pinot Gris, Riesling Renano, Sauvignon Blanc and Pinot Noir). Samples were kept on lees during 18 months. The volatile profile, phenolic compounds and antioxidant activity were determined by GC-FID and GC-MS; HPLC-UV-Vis; ABTS, FRAP and DPPH methods, respectively. The influence of Traditional, Charmat and Asti methods on the volatile composition of sparkling wines, was evaluated in Moscato Giallo variety. The same must was used for Traditional, Charmat and Asti methods, and the aromatic profile was determined by CG-FID and GC-MS. To evaluate the effects of aging time on "sur lie" lees, classical oenological parameters, antioxidant activity, total polyphenols, absorbance at 420 nm, orto-diphenols, total flavanols and sensorial analysis were evaluated in samples from Goethe, Villenave, Niagara and Chardonnay varieties, kept during 8, 16 and 24 months above lees. In the study of sparkling wines elaborated from classic and innovative varieties, tyrosol was in highest concentration among other phenolic compounds; twenty-five compounds were found to be associated with the aromatic profile and the isoamyl acetate concentrations were high in all samples evaluated, particularly in Moscato Embrapa .High concentrations of monoterpenes such as linalool were also observed in samples of Riesling Renano, and geraniol, in samples of Moscato Embrapa. Principal components and clusters analysis of volatile compounds and varieties showed a clearly separation in two groups, one16with innovative varieties Moscato Embrapa, Niagara and Villenave, and a second group with other varieties. In study of methods of preparation, sparkling wines prepared by traditional method had the highest concentration of volatile compounds, and the sparkling wines produced by Asti method presented the lowest concentration. The influence of method of preparation on the volatile composition of sparkling wines Moscato Giallo was confirmed by multivariate principal component analysis, which showed good separation in three different groups, according to preparation method used. In the study of the times of aging on lees, sensorial analysis showed that the sparkling wines Niagara and Goethe varieties had better overall impression with less time on lees "sur lie". Sparkling wines produced with Chardonnay and Villenave varieties showed the best results in overall impression for samples with greater time on lees
Obtaining well-posedness in mathematical modelling of fluvial morphodynamics
No full textRivers, Ports, Waterways and Dredging Engineerin
- …
