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Φυσικοχημική μελέτη του καταλυτικού συστήματος της διεργασίας παρασκευής θειϊκού οξέοςΚαρύδης, Δημήτρης 17 December 2009 (has links)
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Determinacao do coeficiente de difusao do acido oxalico em meio sulfurico pelos metodos da cronopotenciometria e do diafragma porosoCHIERICE, GILBERTO O. 09 October 2014 (has links)
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00886.pdf: 3186592 bytes, checksum: 02aa449d230c78ebeaa2a6f79a1c56d9 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Quimica, Universidade de Sao Paulo - IQ/USP
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Estudo do pré-tratamento do bagaço de cana-de-açúcar e caracterização físico-químicaMorais, Alaine Patrícia da Silva [UNESP] 27 August 2010 (has links) (PDF)
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morais_aps_me_botfca.pdf: 687506 bytes, checksum: baad0742c0a39bca3a4a2b5908c9cedf (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O bioetanol é um combustível produzido por meio da fermentação do açúcar do caldo da cana, que representa apenas um terço do carbono (energia), presente na planta. Atualmente, estão sendo feitos esforços para o aproveitamento do restante da biomassa, divididos entre as folhas e bagaço do colmo. Esta biomassa lignocelulósica poderia ser aproveitada para produção de etanol, desde que submetida a processos hidrolíticos químicos (ácidos e bases) e enzimáticos gerando açúcares fermentescíveis. Pela fermentação alcoólica é possível a produção de etanol a partir da mistura de açúcares liberados. Neste trabalho procurou-se a padronização de procedimentos para avaliar o pré-tratamento físico e químico do bagaço da cana-de-açúcar, aliado a diferentes tratamentos térmicos a partir de duas granulometrias de bagaço (1,1 e 2,5 mm). Para o delineamento experimental, utilizou-se tratamentos ajustados em fatorial 4 X 5, sendo que as variáveis foram a influência do tempo de pré-tratamento (0, 15, 30, 45 e 60 minutos) e concentração de ácido sulfúrico (H2SO4) a 7 e 9%. Estes fatores exerceram influência sobre o desempenho da pré-hidrólise, medido pela liberação açúcares redutores (AR) na solução e a % de espécies químicas no bagaço prétratado / Bioethanol fuel is produced through the fermentation of sugar cane juice, which representes only a third of the carbon (energy) present in the plant. Currently, efforts are being made to the use of the remaining biomass, divided among the leaves and seed stalk. This lignocellulosic biomass could be used for ethanol production, provided that undergo hydrolytic process chemicals (acids and bases) and enzymatic generating fermentable sugars. For fermentation is possible to produce ethanol from mixed sugars released. This research is the standardization of procedures to assess the pre-treatment physical and chemical properties of bagasse from sugar cane, coupled with different thermal treatments from two particle sizes of mulch (1,1 and 2,5 mm). For this experiment, we used adjusted treatments in a factorial 4 x 5, and the variables were the influence of time of pretreatment (0, 15, 30, 45 and 60 minutes) And concentration of sulfuric acid (H2SO4) 7 and 9%. These factors have exerted influence on the performance of pre-hydrolysis, measured by the release sugars (RS) in the solution, and% of chemical species in the pretreated bagasse
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Estudo da ocorrencia do efeito sinergico na extracao do uranio realizada com a mistura de fosfato de Tri-n-butila e acido Di-(2-etilhexil) fosforico, nos meios nitrico e sulfuricoSHIH, AI 09 October 2014 (has links)
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01373.pdf: 2177648 bytes, checksum: 33aa1e9445adffb063f558969a36d128 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Determinacao do coeficiente de difusao do acido oxalico em meio sulfurico pelos metodos da cronopotenciometria e do diafragma porosoCHIERICE, GILBERTO O. 09 October 2014 (has links)
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00886.pdf: 3186592 bytes, checksum: 02aa449d230c78ebeaa2a6f79a1c56d9 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Quimica, Universidade de Sao Paulo - IQ/USP
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Estudo da ocorrencia do efeito sinergico na extracao do uranio realizada com a mistura de fosfato de Tri-n-butila e acido Di-(2-etilhexil) fosforico, nos meios nitrico e sulfuricoSHIH, AI 09 October 2014 (has links)
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01373.pdf: 2177648 bytes, checksum: 33aa1e9445adffb063f558969a36d128 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Removal of sulfuric acid aerosol particles from air streams by turbulent deposition and diffusiophoresisAzarniouch, Mahmoud Kamran January 1974 (has links)
No description available.
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Formaldehyde instrument development and boundary layer sulfuric acid: implications for photochemistryCase Hanks, Anne Theresa 31 March 2008 (has links)
This work presents the development of a laser-induced fluorescence technique to measure atmospheric formaldehyde. In conjunction with the technique, the design of a compact, narrow linewidth, etalon-tuned titanium:sapphire laser cavity which is pumped by the second harmonic of a kilohertz Nd:YAG laser is also presented. The fundamental tunable range is from 690-1100 nm depending on mirror reflectivities and optics kit used. The conversion efficiency is at least 25% for the fundamental, and 2-3% for intracavity frequency doubling from 3.5-4W 532 nm pump power. The linewidth is < 0.1 cm-1, and the pulsewidth is 18 nsec.
Also presented are observations of gas-phase sulfuric acid from the NEAQS-ITCT 2K4 (New England Air Quality Study Intercontinental Transport and Chemical Transformation) field campaign in July and August 2004. Sulfuric acid values are reported for a polluted environment and possible nucleation events as well as particle growth within the boundary layer are explored. Sulfate production rates via gas phase oxidation of sulfur dioxide are also reported. This analysis allows an important test of our ability to predict sulfuric acid concentration and probe its use as a fast time response photochemical tracer for the hydroxyl radical, OH. In comparison, the NASA time-dependent photochemical box model is used to calculate OH concentration. Nighttime H2SO4 values are examined to test our understanding of nocturnal OH levels and oxidation processes.
In comparison, sulfuric acid from a large ground based mission in Tecámac, México (near the northern boundary of Mexico City) during MIRAGE-Mex field campaign (March 2006) is presented. The observations in conjunction with the NASA LARc Photochemical box model are used to explore ozone production, nitrate and sulfate formation, and radical levels and radical production rates during the day. The one minute observations of sulfuric acid, sulfur dioxide, and aerosol surface area were again used to calculate OH levels assuming steady state, and are in good agreement with observations of OH (R2 = 0.7). Photochemical activity is found to be a maximum during the morning hours, as seen in ozone and nitrate formation.
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Development and usability evaluation of a multimedia e-learning resource for electrolyte and acid-base disordersDavids, Mogamat Razeen 03 1900 (has links)
Thesis ((DMed)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: We have developed an innovative multimedia e-learning resource, the Electrolyte
Workshop, to provide students and clinicians with instruction and the opportunity for
simulated practice in managing electrolyte and acid-base disorders. Our teaching
approach is built around relevant physiology and makes use of real cases and
storytelling to engage the learner. We have documented the challenges encountered
during the development process and have made recommendations for the managing
of similar projects.
While there are many factors that must be in place to ensure successful e-learning,
this dissertation focuses on an important but under-appreciated factor, namely the
usability of the computer interface. Usability describes how easy technology
interfaces are to use and is routinely evaluated and optimized in the software
development industry. This is not yet the case with e-learning, especially in the area
of medical education. Poor usability limits the potential benefit of educational
resources, as this means that learners will struggle with the interface as well as with
the challenges of the content presented.
A comprehensive usability evaluation of our Electrolyte Workshop was completed.
This included testing with typical end-users, where data were collected via
standardized questionnaires and by observing and analysing their interactions with
our application. We employed heuristic evaluation as an additional approach and
assembled a panel of experts to evaluate our application against a set of heuristics,
or principles of good interface design.
Many serious usability problems were identified, thus severely limiting the potential
educational impact of our Electrolyte Workshop. There was a striking disconnect
between the objective measures of usability and self-reported questionnaire data.
Our user-testing data make a useful contribution to the debate on how many users
are required to find most of the usability problems in an interface. Heuristic
evaluation proved to be a very efficient approach. However, both user testing and heuristic evaluation detected serious problems which were missed with the other
method.
These evaluations informed a comprehensive revision of our application and we
could then compare the original with an optimized version in a randomized trial. We
found large improvements in objective usability measures, which are likely to
increase the satisfaction and motivation of learners. There were similar scores on
measures of learning. This was not surprising as our participants were all relatively
high-knowledge learners and not novices as regards the subject matter.
Our study clearly indicates that the usability evaluation of e-learning resources is
critical, and provides an example of how clinician-teachers can improve the usability
of the resources they develop. Usability should be evaluated as a routine part of the
development and implementation of e-learning materials, modules and programmes.
This should start with the earliest versions of the resource, when making changes is
easier and less costly. We have demonstrated that a combination of methods should
be employed and have highlighted the utility of heuristic evaluation. An iterative
approach should be followed, with several cycles of testing and re-design. User
testing should always include the study of objective usability measures and not rely
only on self-reported measures of user satisfaction. / AFRIKAANSE OPSOMMING: Ons het ’n innoverende multimediahulpbron vir e-leer, die Electrolyte Workshop,
ontwikkel om studente en klinici van ’n onderrighulpmiddel sowel as die geleentheid
vir gesimuleerde oefening in die hantering van elektroliet en suur-basis stoornisse te
voorsien. Ons onderrigbenadering is gegrond op relevante fisiologie en maak
gebruik van werklike gevalle en vertelkuns om die leerder te betrek en te boei. Ons
het die uitdagings gedurende die ontwikkelingsproses opgeteken en aanbevelings
oor die bestuur van soortgelyke projekte gedoen.
Hoewel suksesvolle e-leer van etlike faktore afhang, konsentreer hierdie
verhandeling op ’n belangrike dog onderskatte faktor, naamlik die bruikbaarheid van
die rekenaarkoppelvlak. Bruikbaarheid verwys na die gemak waarmee
tegnologiekoppelvlakke gebruik kan word, en word gereeld in die
sagtewareontwikkelingsbedryf beoordeel en verbeter. Tog is dit nog nie die geval
met e-leer nie, veral op die gebied van mediese onderrig. Swak bruikbaarheid
beperk die moontlike voordeel van opvoedkundige hulpbronne, aangesien leerders
voor die dubbele uitdaging van ’n ingewikkelde koppelvlak én die voorgeskrewe
inhoud te staan kom.
’n Omvattende bruikbaarheidsbeoordeling is van die Electrolyte Workshop
onderneem. Dit het toetsing met tipiese eindgebruikers ingesluit, waarvoor data met
behulp van gestandaardiseerde vraelyste ingesamel en gebruikers se interaksie met
die toepassing waargeneem en ontleed is. Ons het heuristiese evaluering as
bykomende benadering gebruik en ’n kennerspaneel saamgestel om ons toepassing
aan die hand van ’n stel heuristiek, oftewel beginsels van goeie koppelvlakontwerp,
te beoordeel.
’n Hele aantal ernstige bruikbaarheidsprobleme is uitgewys, wat die moontlike
opvoedkundige impak van die Electrolyte Workshop erg beperk. Daar was merkbare
teenstrydigheid tussen die objektiewe bruikbaarheidsmaatstawwe en die
selfaangemelde vraelysdata. Ons gebruikerstoetsdata lewer ’n waardevolle bydrae tot die debat oor hoeveel gebruikers nodig is om die meeste van die
bruikbaarheidsprobleme met ’n koppelvlak te ontdek. Heuristiese evaluering was ʼn
baie doeltreffende benadering. Tog het gebruikerstoetsing op sekere ernstige
probleme afgekom wat heuristiese evaluering misgekyk het, en andersom.
Hierdie beoordelings het as grondslag gedien vir ’n omvattende hersiening van die
toepassing, waarna ons die oorspronklike weergawe in ’n verewekansigde proef met
’n verbeterde weergawe kon vergelyk. Die objektiewe bruikbaarheidsmaatstawwe
het groot verbeterings getoon, wat waarskynlik leerders se tevredenheid en
motivering sal verhoog. Leermaatstawwe het soortgelyke tellings opgelewer. Dít was
egter te wagte gewees, aangesien die deelnemers almal betreklik ingelig was oor die
vakmateriaal, eerder as nuwelinge.
Ons studie het bevestig dat die bruikbaarheidsbeoordeling van e-leerhulpbronne
noodsaaklik is, en bied ’n voorbeeld van hoe klinici-opvoeders bruikbaarder
hulpbronne kan ontwikkel. Bruikbaarheid behoort as ’n roetinedeel van die
ontwikkeling en inwerkingstelling van e-leermateriaal, -modules en -programme
beoordeel te word. Dit behoort reeds by die vroegste weergawes van die hulpbron te
begin, wanneer dit makliker en goedkoper is om veranderinge aan te bring. Ons het
ook getoon dat ’n kombinasie van metodes gebruik behoort te word, en het die nut
van heuristiese evaluering beklemtoon. ’n Herhalende benadering moet gevolg word,
met etlike siklusse van toetsing en herontwerp. Gebruikerstoetsing behoort altyd die
beoordeling van objektiewe bruikbaarheidsmaatstawwe in te sluit, en moenie slegs
op selfaangemelde maatstawwe van gebruikerstevredenheid staatmaak nie.
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Non-covalent functionalization of carbon nanostructures : a DFT study / Fonctionnalisation non covalente de structures nano-carbonées : une étude DFTHu, Tao 06 May 2013 (has links)
Le dopage non covalent de nanostructures carbonées par transfert de charge depuis/vers des molécules donneuses ou acceptrices (EDA) ou bien par des molécules d’acide sulfurique H2SO4, est considéré comme potentiellement intéressant pour de nombreuses applications. Parmi celles-ci on peut citer: capteur chimique, transistor à effet de champ, et d’autre l'électronique. Cependant, d'un point de vue théorique, on en sait peu au sujet de ces processus de transfert de charge par électrons ou par trous.Dans un premier temps, nous nous sommes intéressés à l’interaction entre des molécules d’acide sulfurique et des nanostructures modèles, car elles sont capables de doper des nanotubes, de s’intercaler dans le graphite et même d’aligner les tubes dans une phase nématique, ce qui pourrait mener à la création de matériaux composites à forte valeur ajoutée.Bien que certaines études théoriques DFT ont été menées récemment, leurs résultats restent source de confusion. Par exemple, même s’il est rapporté un transfert de charge entre une molécule de H2SO4 et un plan de graphène, tous nos efforts pour reproduire ces calculs ont été infructueux. Nous proposons dans ce travail de thèse, un mécanisme de réaction qui expliquent la "protonation" des parois du tube, tel que proposé dans la littérature. Enfin nous proposons un scénario possible pour une meilleure compréhension de la structuration à grande échelle des molécules d'acide autour de points d'ancrage, telles que des défauts, de la structure carbonée / Non-covalent doping of carbon nanostructures by charge transfer from/to donor/acceptor molecules (EDA) or by H2SO4 molecules, be it with holes or electrons, is usually thought as potentially interesting for many applications of carbon based nano-devices. However, from a theoretical point of view, little is known about such “charge transfer” processes.Employing first-principles method based on Density Functional Theory (DFT), we have studied in details, and proposed a model to rationalize, the interaction between a prototypical donor molecule the tetrathiafulvalene (TTF), a standard acceptor organic molecule, tetracyanoethylene (TCNE) and carbon nanostructures: graphene layer and SWNTs with various chiral indices. Main results concern structural and thermodynamic aspects including dispersion forces effects, and evidently electronic structure modifications of the nanostructures. Various adsorption modes and concentration effects have been investigated. At very low coverage values, we have reported a charge transfer between graphene and TCNE or TTF. Moreover, we have shown that the charge transfer can be enhanced by increasing the concentration of those two EDA molecules, as it has been demonstrated experimentally. Those results are beneficial for comprehending the nonchemical doping mechanism in graphene structure by means of charge transfers. Considering the interaction between these prototypical molecules and carbon nanotubes, we have found that charge transfers tend to decrease while the curvature of nanotube is increasing. Besides, a strong influence of the metallic/semi-conductor character of the SWNTs can be observed and be explained by the change of polarisability of the curved carboneous substrates. Additionally, we have studied the adsorption properties of sulfuric acid molecules, in its non-hydrated form, on carboneous nanostructures. Against the common believe, no charge transfer is observed in the H2SO4@graphene or H2SO4@CNTs cases, even at very high concentrations. Instead, in order to elucidate the origin of p-doping observed experimentally, we have proposed that molecule is responsible of the reversible doping. Besides we have shown that a proton transfer could cause the experimental phenomenon of crystallization of H2SO4 molecules on SWNT’s surface. Finally in such process, defects like vacancy are of first importance, since they could provide anchorage points for hydrogen atoms. The results of the present work will certainly help to understand the charge transfer and doping mechanism of carbon nanostructures by means of non-covalent functionalization, which is a promising method for their future applications
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