5,646 research outputs found
Equity in the Grain System: Corn, Masa and Tortillas in the Pacific Northwest
Slides from a presentation given at the Cascadia Grains Conference, South Puget Sound Community College, Olympia, Wash. in January 2019
Not Everyone Who Speaks Spanish is From Spain: Taino Survival in the 21st Century Dominican Republic
The national identity of the Dominican Republic is based on an idealized story of three cultural roots-- Spanish, African, and Taíno--with a selective amnesia of the tragedies and struggles inherent to the processes of colonial domination and resistance. Further, African, Taíno and mixed AfroMestizo culture have been marginalized in favor of nationalist ideologies of progress and civilization found in the embrace of Hispanidad and Catholicism. In such a way, Dominicans have been disconnected from their African, their indigenous, and their mixed Afro-Mestizo Criollo (Creole) ancestry and cultural heritage, even though it is these ancestries and heritages which mark Dominicans with the significant emblems of their contemporary identity.
In this paper, I assess the survival of Taíno culture by building on the work of two important studies addressing Taíno heritage in the Dominican Republic— Bernardo Vega\u27s (1981) “La herencia indígena en la cultura dominicana de hoy” and Garcia Arévalo\u27s (1988) “Indigenismo, arqueología, e identidad nacional.” My conclusion is that there is significant cultural heritage of Taíno origin that has persisted to this day. That heritage, together with the historical evidence for Taíno survival presented by my colleagues Lynne Guitar and Jorge Estevez, points me to the understanding that the Taíno people were never extinct but, rather, survived on the margins of colonial society to the present
Síntese de líquidos iónicos específicos para captura de CO2
Mestrado em Engenharia QuímicaA redução das emissões de CO2 tem alcançado especial relevância por ser
este gás um dos máximos responsáveis do efeito estufa e que da origem ao já
conhecido aquecimento global. Nos últimos anos, alguns estudos têm proposto o
uso de líquidos iónicos (LIs) como absorventes alternativos à captura de CO2, já que
contam com propriedade relevantes tais como alta estabilidade térmica, amplio
rango de temperaturas em estado líquido, baixa volatilidade, boa solubilidade do
CO2 e a possibilidade de ajustar as suas propriedades através da seleção de iões.
Esta dissertação se ajusta as atividades experimentais realizadas no Instituto de
Carboquímica (ICB-CSIC), nomeadamente a síntese y caracterização de líquidos
iónicos, seguida pelo estudo da captura de CO2 nos líquidos iónicos assim como as
condições de operação mais adequadas para a captura, principalmente pressão
(atmosférica, 5bar y 10bar).
Inicialmente, realizou-se a síntese de LIs basada na reação de metástase com
acetato de sódio (NaCH3COO) em presença de nove dissolventes, com objeto de
encontrar o mais adequado para realizar a síntese de LIs usando sais de sódio.
Outro método utilizado foi o de metástase com óxido de prata (Ag2O) em meio
aquoso, basado na combinação do catião 1-butil-3-metilimidazolio [Bmim+] com os
aniões: acetato ([Ac-]), ftalato ([ft-]), 1-naftoato ([1-naf-]), fenolato ([Fen-]),
hidroquinolato ([HQ-]), pirocatecolato ([PC-]) y pentafluorofenolato ([FenF5
-]).
Também foram propostas outras alternativas de síntese com hidróxido de chumbo
(Pb(OH)2) e com hidróxido de 1-butil-3-metilimidazolio ([Bmim][OH]). A
caracterização dos diversos LIs sintetizados foi feita usando diversas técnicas, tais
como: cromatografia iónica, análise elemental, análise por espectroscopia
infravermelha, e análise termogravimétrica.
As principais conclusões deste estudo são resumidas a continuação. Foi
possível sintetizar diversos LIs, atingindo em vários casos purezas entre os 80 e 98%.
O valor de pKa do ácido do anião correspondente tem um papel importante no tipo
de captura produzido (quimissorção e/ou fisissorção), e consequentemente na
capacidade de captura, observando-se que quanto maior é o valor de pKa maior é a
capacidade de captura. Outra variável importante é a pressão de trabalho, quanto
maior a pressão, maior é a capacidade de captura. Assim, verificou-se que a difusão
de CO2 sobre o LI influência a captura e está direitamente relacionada com a massa
de LI.
A partir dos resultados obtidos, conclui-se que a viscosidade e o pKa do ácido
do anião correspondente podem desenvolver um papel muito importante no
comportamento dos líquidos iónicos e que estas propriedades se podem ajustar
selecionando adequadamente os constituintes do líquido iónico.La reducción de las emisiones de CO2 ha alcanzado especial relevancia por
ser este gas uno de los máximos responsables del efecto invernadero que produce
el conocido calentamiento global. En los últimos años, algunos estudios han
propuesto el uso de líquidos iónicos (LIs) como absorbentes alternativos a la
captura de CO2, ya que poseen interesantes propiedades como alta estabilidad
térmica, amplio rango de temperaturas en estado líquido, baja volatilidad, buena
solubilidad del CO2 y la posibilidad de ajustar sus propiedades mediante la selección
de iones. La presente memoria se ciñe a las actividades experimentales realizadas
en el Instituto de Carboquímica (ICB-CSIC), como síntesis y caracterización de
líquidos iónicos, seguida por el estudio de la captura de CO2 en los líquidos iónicos
así como las condiciones de operación más adecuadas para la captura de CO2,
principalmente presión (atmosférica, 5bar y 10bar).
Inicialmente se llevó a cabo la síntesis de LIs basada en la reacción de
metátesis con acetato de sodio (NaCH3COO) en presencia de nueve disolventes, con
objeto de encontrar el más indicado para llevar a cabo la síntesis de LIs usando sales
de sodio. Otro método empleado fue el de metátesis con oxido de plata (Ag2O) en
medio acuoso, basado en la combinación del catión 1-butil-3-metilimidazolio
[Bmim+] con los aniones: acetato ([Ac-]), ftalato ([ft-]), 1-naftoato([1-naf-]), fenolato
([Fen-]), hidroquinolato ([HQ-]), pirocatecolato ([PC-]) y pentafluorofenolato
([FenF5]). También fueron propuestas otras alternativas de síntesis con hidróxido de
plomo (Pb(OH)2) y con hidróxido de 1-butil-3-metilimidazolio ([Bmim][OH]. Se llevó
a cabo la caracterización de los diferentes LIs sintetizados utilizando diversas
técnicas, tales como: cromatografía iónica, análisis elemental, análisis por
espectroscopía infraroja y análisis termogravimétrico.
Las principales conclusiones extraídas de este estudio se resumen a
continuación. Se ha logrado sintetizar diversos LIs, alcanzándose en varios casos
purezas entre el 90 y 98,4%. El valor de pKa del ácido del anión correspondiente
juega un papel clave sobre el tipo de captura que se produce (quimisorción y/o
fisisorción), y por lo tanto sobre la capacidad de captura, observándose que cuanto
mayor es el valor de pKa mayor es la capacidad de captura. Otro aspecto clave lo
constituye la presión de trabajo, advirtiéndose que conforme se aumenta la
presión, aumenta la capacidad de captura. Asimismo, se ha determinado que la
difusión de CO2 sobre el LI tiene una gran influencia sobre la captura y está
directamente relacionada con la masa de LI.
A partir de los resultados obtenidos, se puede concluir que la viscosidad y el
pKa del anión del ácido correspondiente pueden desempeñar un papel muy
importante en el comportamiento de los líquidos iónicos y que estas propiedades se
pueden ajustar seleccionando adecuadamente los constituyentes del líquido iónico.The reduction of the CO2 emissions has reached special importance by being
this gas one of the most responsible of the greenhouse effect that produces the
global warming. In recent years, some studies have proposed the use of ionic liquids
(ILs) as an alternative absorbent to CO2 capture, since they possess interesting
properties as high thermal stability, wide liquid range, low volatility, high CO2
solubility and the possibility to adjust their properties by means of the selection of
ions. This work is related to the experimental activities carried out at the Instituto
de Carboquímica (ICB-CSIC), as synthesis and characterization of ionic liquids,
followed by the study of CO2 capture in the ionic liquids and the most adequate
conditions of operation for this capture, mainly pressure (atmospheric, 5bar and
10bar).
Initially, the synthesis of ionic liquids was carried out through the metathesis
reaction with sodium acetate (NaCH3COO) in the presence of nine solvents, with
the purpose of finding the most indicated to carry out the synthesis of ILs using
sodium salts. Other method used was the metathesis with silver oxide (Ag2O) in
aquous medium, based on the combination of the cation 1-butil-3-metilimidazolio
[Bmim+] with the anions: acetate ([Ac-]), phtalate ([ft-]), 1-naphthoate ([1-naf-]),
phenolate ([Fen-]), hydroquinolate ([HQ-]), pyrocatecholate ([PC-]) and
penthafluorofenolate ([FenF5-]). Other alternatives were also applied using lead(II)
hydroxide (Pb(OH)2) and 1-butyl-3-methylimidazolium hydroxide ([Bmim][OH]). The
characterization of the ILs was carried out using diverse techniques, such as: ionic
chromatography, elemental analysis, infrared spectroscopy and thermogravimetric
analysis.
The main conclusions extracted from this work are summarized as follows.
Diverse ILs have been synthesized, with purities between 90 and 98,4%. The pKa
value of the acid of the corresponding anion plays a key role on the type of capture
that is produced (chemisorption and/or physisorption), and therefore on the
capacity of capture, concluding that as much as greater is the value of pKa greater is
the capture capacity. Another key aspect is the pressure, observing that when the
pressure is higher, the capacity of capture is greater. Also, it has been determined
that the diffusion of CO2 on the IL has a great influence on the capture capacity and
is directly related to the mass of IL.
From the results obtained, it can be concluded that the viscosity and the pKa
value of the acid of the corresponding anion can play a very important role in the
behavior of the ionic liquids and that these properties can be adjusted making a
good choice of the constituents of the ionic liquid
Studies of neutron dissociation at FermiLab energies
The characteristics of diffraction dissociation of neutrons into p systems at high energies were examined. A substantial correlation is observed between the mass and the t of the produced system. The spin structure of the p amplitudes at low mass is very complex, but is described surprisingly well by the simple Deck Mechanism. Both -exchange and proton-exchange contributions are evident in diffractive production. The t- channel and s-channel helicity amplitudes contain comparable contributions from flip and nonflip terms and the produced states are not restricted to those expected on the basis of the Morrison rule. (auth
Prospects for probing the gluon density in protons using heavy quarkonium hadroproduction
We examine carefully bottomonia hadroproduction in proton colliders,
especially focusing on the LHC, as a way of probing the gluon density in
protons. To this end we develop some previous work, getting quantitative
predictions and concluding that our proposal can be useful to perform
consistency checks of the parameterization sets of different parton
distribution functions.Comment: LaTeX, 14 pages, 6 EPS figure
Quark Mass Effects in Fermionic Decays of the Higgs Boson in Perturbative QCD
The results of analytical evaluation of QCD contributions due
to the nonvanishing quark masses to
are presented. The ``triangle anomaly'' type contributions are included. As a
byproduct the logarithmic contributions are evaluated. The
results are presented both in terms of running and pole quark masses. The
partial decay modes and are considered. The calculated corrections decrease the absolute
value of large and negative massless limit coefficient by in the intermediate mass region and by 1\%20\% in the low mass region
which, however, is experimentally ruled out.
The results are relevant for decay mode for the
higher Higgs mass region where the mass effects are large and important. The
high order corrections remove a very large discrepancy between the results for
in terms of running and pole quark
masses almost completely and reduce the scale dependence from about 40\% to
nearly 5\%.Comment: 16 pages, LATeX, +5 figures available upon request, preprint OITS-543
(University of Oregon, USA, May 1994). ( Additions are made: Previous general
result for the H-->qq is applied to the H-->tt decay mode where the
calculated corrections are significant.
Gas and soot formed in the dimethoxymethane pyrolysis. Soot characterization
The many simultaneous processes occurring within in a diesel engine make difficult a thorough understanding of the mechanisms responsible for reduction of soot and/or NOX when an oxygenated compound is added to diesel fuel. Thus, in order to explore the use of oxygenated compounds as biofuels/additives, it is interesting to study their conversion under well-controlled laboratory conditions, together with kinetic studies that help to interpret and understand the reaction schemes that occur during such processes. The aim of this work has been to contribute to the knowledge of the dimethoxymethane (DMM) pyrolysis, one of the oxygenated compounds proposed in literature as alternative fuel. In this way, the influence of pyrolysis temperature (1075–1475¿K) and inlet fuel concentration (33,333 and 50,000¿ppm DMM) on the sooting propensity of DMM, soot reactivity and its properties is analyzed. Therefore, this work includes pyrolysis experiments under different experimental conditions, focusing on the gas-phase analysis and the soot formation, together with a gas-phase model. Additionally, the interaction of soot with O2 and with NO has been studied, and since soot properties are important on the oxidation rate, selected soot samples have been characterized by different instrumental techniques (elemental analysis, physical adsorption with N2, Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), and Raman spectroscopy)
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