In spite of their high abundance and importance, aqueous systems are enigmatic on the microscopic scale. In order to obtain information about their geometrical and electronic structure, simple aqueous solutions have been studied experimentally by photo- and Auger electron spectroscopy using the novel liquid micro-jet technique in conjunction with synchrotron radiation. The thesis is thematically divided into three parts. In the first part we utilize the surface sensitivity of photoelectron spectroscopy to probe the distributions of solutes near the water surface. In agreement with recent theoretical predictions we find that large polarizable anions, such as I- and ClO4-, display enhanced surface propensities compared to smaller rigid ions. Surface effects arising from ion-ion interactions at higher electrolyte concentrations and as function of pH are investigated. Studies of linear mono-carboxylic acids and benzoic acid show that the neutral molecular forms of such weak acids are better stabilized at the water surface than their respective conjugate base forms. The second part examines what type of information core-electron spectra can yield about the chemical state and hydration structure of small organic molecules in water. We demonstrate that the method is sensitive to the protonation state of titratable functional groups and that core-level lineshapes are dependent on local water hydration configurations. Using a combination of photoelectron and X-ray absorption spectroscopy we also show that the electronic re-arrangement upon hydrolysis of aldehydes yields characteristic fingerprints in core-level spectra. In the last part of this thesis we study ultrafast charge delocalization dynamics in aqueous solutions using resonant and off-resonant Auger spectroscopy. Intermolecular Coulombic decay (ICD) is found to occur in a number of core-excited solutions where excess energy is transferred between the solvent and the solute. The rate of ultrafast electron delocalization between hydrogen bonded water molecules upon oxygen 1s resonant core-excitation is found to decrease upon solvation of inorganic ions. The presented work is illustrative of how core-level photoelectron spectroscopy can be valuable in the study of fundamental phenomena in aqueous solutions.

This thesis examines sulfide oxidation in 4 physically and mineralogically diverse acid sulfate soil (ASS) materials collected from coastal floodplain sites in north-eastern New South Wales. The aim of this study is to gain further understanding of the process of sulfide oxidation in ASS materials, which will allow improved and more effective management strategies to be applied to these materials. The process of sulfide oxidation was examined using laboratory incubation experiments. The oxidation of pyrite was the primary cause of initial acidification of the ASS materials studied. Although the acid volatile sulfur fraction increased in concentration by an order of magnitude over the initial 8 days of incubation, the subsequent oxidation of this fraction did not result in substantial acidification. Sulfate (SO42-) was the dominant sulfur species produced from sulfide oxidation, however, water-soluble SO42- was a poor indicator of the extent of sulfide oxidation. The sulfoxyanion intermediates thiosulfate (S2O32-) and tetrathionate(S4O62-) were only detected in the early stages of incubation, and their relative abundance appeared to be pH dependent. The diminishing presence of these 2 sulfur species as oxidation progressed was indicative that ferric iron (Fe3+) and bacterial catalysis were driving the oxidation processes. The rate of sulfide oxidation, and consequent rate of acidification, was highly dependent on the soil pH and oxygen availability. Accelerated sulfide oxidation was only observed at low pH (i.e. pH < 4.0) when oxygen availability was not limited. The application of sub-optimal amounts of neutralising agents prevented severe soil acidification in the short-term (i.e. up to 2 months), but had little effect on decreasing the rate of sulfide oxidation and acidification in the long-term. Sub-optimal amounts of CaCO3 accelerated sulfide oxidation and acidification of the peaty marcasitic ASS material resulting in elevated soluble Fe and Al concentrations. For some of the ASS materials, sub-optimal applications of seawater-neutralised bauxite refinery residue (SNBRR) also resulted in elevated soluble Al concentrations. The response of partially-oxidised ASS materials to the exclusion of oxygen was variable. The rate of sulfide oxidation, acidification and the production of soluble oxidation products generally decreased markedly when subjected to anoxia. However, especially in highly acidic ASS materials (i.e. pH < 3.5), sulfide oxidation and acidification generally occurred (albeit at much slower rates), most probably due to oxidation by Fe3+. Rapid sulfide re-formation occurred in the peat ASS material that had been oxidised for 63 days, with 0.47% reduced inorganic sulfur (SCR) formed over 60 days of anoxia. Biogeochemical sulfide formation consumes acidity, however, sulfide re-formation was ineffective in reversing acidification under the conditions of this experiment. The peroxide oxidation methods examined were method dependent and substantially underestimated peroxide oxidisable sulfur, sulfidic acidity and net acidity. The precipitation of jarosite during peroxide oxidation was a major factor contributing to the underestimation in these ASS materials. Clay mineral dissolution may contribute towards the underestimation of both sulfidic and net acidity using peroxide oxidation methods. The atmospheric loss of sulfur and acidity was also identified as a possible additional interference. This study has shown that the initial pH of an ASS material is a useful indicator (additional to those already used) of the potential environmental hazard of an ASS material when oxygen is expected to be non-limiting, such as when ASS materials are excavated and stockpiled. The recommended action criteria need to be reassessed as the data indicate that the current criteria are conservative for alkaline and neutral ASS materials, but should be lowered for all acidic ASS materials (i.e. pH < 5.5) to 0.03% sulfide regardless of texture. Alternative strategies are necessary for the management of ASS materials that are subject to oxidation when the addition of optimal rates of neutralising materials cannot be ensured. The treatment of sites containing actual ASS materials by management strategies that rely on oxygen exclusion need to be accompanied by strategies that include either acid neutralisation or containment in order to reduce acid export from the site. The peroxide oxidation methods examined were subject to substantial interferences, and consequently are unable to reliably provide accurate measurements of the reduced inorganic sulfur fraction, sulfidic acidity, and net acidity in ASS materials.

Ce travail de thèse se focalise sur l'impact des propriétés acido-basiques des catalyseurs (quantité et force des sites) dans la production d’acroléine par couplage oxydant d’alcools en phase gazeuse. L'influence du rapport entre site acides et sites basiques des catalyseurs a été étudiée dans la condensation aldolique de l'acétaldéhyde et du formaldéhyde en acroléine, réalisée en conditions oxydantes. Les données et corrélations obtenues ont donné des informations indispensables à l’identification des paramètres qui doivent être modifiés afin d'améliorer la sélectivité en acroléine. La première réaction du procédé implique l'oxydation du méthanol et de l'éthanol respectivement en formaldéhyde et acétaldéhyde sur un catalyseur rédox de type FeMoOx.Ensuite, l'aldolisation croisée des deux aldéhydes et la déshydratation en acroléine sont effectuées sur des catalyseurs acido-basiques.Les alcools impliqués dans ce procédé pouvant dériver de la biomasse, cette nouvelle voie de production d'acroléine présente un intérêt élevé puisqu'elle peut remplacer la production actuelle d'acroléine basée sur des ressources fossiles (aujourd'hui l’acroléine est produite industriellement par oxydation du propylène).Le catalyseur optimal doit présenter des caractéristiques amphotères avec une quantité similaire de sites basiques et acides. Une présence modérée et équilibrée de sites acides et basiques améliore le rendement en acroléine et déplace à plus haute température la production des oxydes de carbone. Parmi tous les catalyseurs étudiés, et grâce à ses propriétés acido-basiques spécifiques, MgO supporté sur silice a été identifié comme étant le meilleur catalyseur pour la condensation aldolique des aldéhydes en acroléine en conditions oxydantes / The present work focuses on the impact of the amount and strength of acidic and/or basic sites on the yield of acrolein produced by alcohols oxidative coupling in gas phase. The influence of acid/base ratio of catalytic sites has been studied in the aldol condensation of acetaldehyde and formaldehyde to acrolein performed in oxidizing conditions. The obtained data and correlations supplied valuable information to understand which parameters have to be modified to improve the acrolein selectivity. The first reaction of the process implies methanol and ethanol oxidation respectively to formaldehyde and acetaldehyde on a FeMoOx redox catalyst. Then the cross-aldolization of the two aldehydes and the dehydration to acrolein is performed on acid/base catalysts. Because the alcohols involved in this process can be bio-sourced, this new route to produce acrolein presents a very high interest, since it can replace the current fossil-based acrolein production (nowadays industrially produced by oxidation of propylene). The optimal catalyst should present amphoteric features with a similar amount of both basic and acidic sites. A moderate and balanced presence of acidic and basic sites improves the acrolein yield and the production of carbon oxides is significantly increased only at high temperature. Among all studied catalysts, MgO supported on silica has been identified as the best catalyst for aldol-condensation of aldehydes to acrolein in oxidizing conditions thanks to a given ratio of basic to acidic sites

Knowledge of the dissociation constants of the ionizable protons of weak acids in aqueous media is of fundamental importance in many areas of chemistry and biochemistry. The pKa value, or equilibrium dissociation constant, of a molecule determines the relative concentration of its protonated and deprotonated forms at a specified pH and is therefore an important descriptor of its chemical reactivity. Considerable efforts have been devoted to the determination of pKa values by deferent experimental techniques. Although in most cases the determination of pKa values from experimental is straightforward, there are situations where interpretation is difficult and the results ambiguous. It is, therefore, not surprising that the capability to provide accurate estimates of the pKa value has been a central goal in theoretical chemistry and there has been a large effort in developing methodologies for predicting pKa values for a variety of chemical systems by differing quantum chemical techniques. A prediction accuracy within 0.5 pKa units of experiment is the desirable level of accuracy. This is a non-trivial exercise, for an error of 1 kcal/mol in estimates of the free energy value would result in an error of 0.74 pKa units. In this thesis ab initio Car-Parrinello molecular dynamics (CPMD) has been used for investigating the Brϕnsted acid-base chemistry of weak acids in aqueous solution. A key issue in any dissociation event is how the solvating water molecules arrange themselves spatially and dynamically around the neutral and dissociated acid molecule. Ab initio methods have the advantage that all solvent water molecules can, in principle, be con- sidered explicitly. One of the factors that has inhibited the widespread use of ab initio MD methods to study the dissociation reaction is that dissociation of weak acids are rare events that require extremely long simulation times before one is observed. The metady- namics formalism provides a solution to this conundrum by preventing the system from revisiting regions of configuration space where it has been in the past. The formalism allows the system to escape the free-energy minima by biasing the dynamics with a history dependent potential (or force) that acts on select degrees of freedom, referred to as collective variables. The bias potentials, modeled by repulsive inverted Gaussians that are dropped during propagation, drive the system out of any free-energy minima and allow it to explore the configuration space by a relatively quick and efficient sampling. The the- sis deals with a detailed investigation of the Brϕnsted acid-base chemistry of weak acids in aqueous solutions by the CPMD-metadynamics procedure. In Chapter 1, current approaches for the theoretical estimation of pKa values are summarized while in Chapter 2 the simulation methodology and the metadynamics sampling techniques used in thisstudy are described. The potential of the CPMD-metadynamics procedure to provide estimates of the acid dissociation constant (pKa) is explored in Chapter 3, using acetic acid as a test sys- tem. Using the bond-distance dependent coordination number of protons bound to the dissociating carboxylic groups as the collective variable, the free-energy profile for the dissociation reaction of acetic acid in water was computed. Convergence of the free-energy profiles and barriers for the simulations parameters is demonstrated. The free-energy profiles exhibit two distinct minima corresponding to the dissociated and neutral states of the acid and the deference in their values provides the estimate for pKa. The estimated value of pKa for acetic acid from the simulations, 4.80, is in good agreement with the experiment at value of 4.76. It is shown that the good agreement with experiment is a consequence of the cancellation of errors, as the pKa values are computed as the difference in the free energy values at the minima corresponding to the neutral and dissociated state. The chapter further explores the critical factors required for obtaining accurate estimates of the pKa values by the CPMD-metadynamics procedure. It is shown that having water molecules sufficient to complete three hydration shells as well as maintaining water density in the simulation cell as close to unity is important. In Chapter 4, the CPMD-metadynamics procedure described in Chapter-3 has been used to investigate the dissociation of a series of weak organic acids in aqueous solutions. The acids studied were chosen to highlight some of the major factors that influence the dissociation constant. These include the influence of the inductive effect, the stabilization of the dissociated anion by H-bonding as well as the presence of multiple ionizable groups. The acids investigated were aliphatic carboxylic acids, chlorine-substituted carboxylic acids, cid and trans-butenedioic, the isomers of hydroxybenzoic acid and phthalic acids and its isomers. It was found that in each of these examples the CPMD-metadynamics procedure correctly estimates the pKa values, indicating that the formulism is capable of capturing these influences and equally importantly indicating that the cancellation of errors is indeed universal. Further, it is shown that the procedure can provide accurate estimates of the successive pKa values of polypro tic acids as well as the subtle deference in their values for deterrent isomers of the acid molecule. Changes in protonation-deprotonation of amino acid residues in proteins play a key role in many biological processes and pathways. It is shown that CPMD simulations in conjunction with metadynamics calculations of the free energy profile of the protonation- deprotonation reaction can provide estimates of the multiple pKa values of the 20 canonical α-amino acids in aqueous solutions in good agreement with experiment (Chapter 5). The distance-dependent coordination number of the protons bound to the hydroxyl oxygen of the carboxylic and the amine groups is used as the collective variable to explore the free energy profiles of the Brϕnsted acid-base chemistry of amino acids in aqueous solutions. Water molecules, sufficient to complete three hydration shells surrounding the acid molecule were included explicitly in the computation procedure. The method works equally well for amino acids with neutral, acidic and basic side chains and provides estimates of the multiple pKa values with a mean relative error with respect to experimental results, of 0.2 pKa units. The tripeptide Glutathione (GSH) is one of the most abundant peptides and the major repository for non-protein sulfur in both animal and plant cells. It plays a critical role in intracellular oxidative stress management by the reversible formation of glutathione disulfide with the thioldisulfide pair acting as a redox buffer. The state of charge of the ionizable groups of GSH can influences the redox couple and hence the pKa value of the cysteine residue of GSH is critical to its functioning. In Chapter 6, it has been reported that ab initio Car-Parrinello Molecular Dynamics simulations of glutathione solvated by 200 water molecules, all of which are considered in the simulation. It is shown that the free-energy landscape for the protonation - deprotonation reaction of the cysteine residue of GSH computed using metadynamics sampling provides accurate estimates of the pKa and correctly predicts the shift in the dissociation constant values as compared to the isolated cysteine amino acid. The dissociation constants of weak acids are commonly determined from pH-titration curves. For simple acids the determination of the pKa from the titration curves using the Henderson-Hasselbalch equation is relatively straightforward. There are situations, however, especially in polypro tic acids with closely spaced dissociation constants, where titration curves do not exhibit clear inflexion and equivalence stages and consequently the estimation of multiple pKa values from a single titration curve is no longer straightfor- ward resulting in uncertainties in the determined pKa values. In Chapter 7, the multiple dissociation constant of the hexapeptide glutathione disulfide (GSSG) with six ionizable groups and six associated dissociation constants has been investigated. The six pKa values of GSSG were estimated using the CPMD-metadynamics procedure from the free-energy profiles for each dissociation reaction computed using the appropriate collective variable. The six pKa values of GSSG were estimated and the theoretical pH-titration curve was then compared with the experimentally measured pH-titration curve and found to be in excellent agreement. The object of the exercise was to establish whether interpretation of pH-titration curves of complex molecules with multiple ionizable groups could be facilitated using results of ab initio molecular dynamics simulations.

A obstrução uretral é uma condição clínica comum em gatos, caracterizada por alterações metabólicas e do equilíbrio hidroeletrolítico e ácido-básico que são potencialmente fatais. Dentre as causas de obstrução uretral, a cistite idiopática é a mais frequentemente observada em diversos estudos. Outras causas incluem urolitíase, tampões uretrais e infecção do trato urinário. Em muitos casos, os gatos encontram-se em estado crítico e a morte pode ocorrer em decorrência de alterações metabólicas, como estado urêmico avançado e hipercalemia. As principais alterações eletrolíticas e do equilíbrio ácido-básico relatadas são hipercalemia, acidose metabólica, hiponatremia e hipocalcemia ionizada. Embora a obstrução uretral seja muito frequente na rotina clínica, estudos para caracterizar a população de gatos acometida ainda são escassos no Brasil. Características relacionadas ao manejo, dieta e perfil dos tutores podem influenciar na manifestação da doença. Os objetivos do presente estudo foram avaliar os parâmetros clínicos e as alterações hematológicas, bioquímicas, urinárias, eletrolíticas e ácido-básicas presentes em gatos com obstrução uretral e a associação entre estas variáveis. Além disso, objetivou-se conhecer as principais causas de obstrução uretral nos gatos atendidos no Hospital de Clínicas Veterinárias da Universidade Federal do Rio Grande do Sul. Para isso, foram incluídos no estudo 28 gatos com diagnóstico de obstrução uretral no período de dezembro de 2015 a dezembro de 2016. Foram obtidos dados referentes ao histórico, exame físico, coletados sangue e urina, além da realização de exames de imagem (radiografia e ultrassonografia abdominal). Em todos os gatos foram realizados hemograma, bioquímica sérica, análise de pH, gases e eletrólitos sanguíneos, urinálise e urocultura. Após, todos os pacientes foram tratados de acordo com um protocolo pré-estabelecido. A causa mais comum de obstrução uretral neste estudo foi a cistite idiopática, que ocorreu em mais de 60% dos casos, seguida de tampões uretrais e infecção do trato urinário. Nenhum caso de urolitíase foi diagnosticado, o que pode ser explicado por fatores como idade, ambiente e estilo de vida dos animais. A maioria dos gatos obstruídos apresentou múltiplos sinais sistêmicos, assim como alterações metabólicas, eletrolíticas e do equilíbrio ácido-básico, principalmente azotemia, hiperlactatemia, acidose metabólica, hipercalemia e hipocalcemia ionizada. Hipotermia, depressão do estado mental, bradicardia e desidratação foram os parâmetros clínicos que tiveram maior quantidade de associação com as alterações metabólicas e podem ser considerados bons preditores clínicos destas desordens. Por outro lado, o lactato não foi considerado um bom preditor de alterações clínicas e laboratoriais neste estudo. / Urethral obstruction is a common and potentially life-threatening condition, characterized by severe metabolic, electrolyte and acid-base disturbances. Among the causes of urethral obstruction, idiopathic cystitis is the most frequent in several studies. Other causes include urolithiasis, urethral plugs and urinary tract infection. In many cases, cats are critically ill and death may occur due to metabolic alterations, such as advanced uremic status and hyperkalemia. The main electrolyte and acid-base balance disorders reported are hyperkalemia, metabolic acidosis, hyponatremia and ionized hypocalcemia. Although urethral obstruction is a very common condition, there are few studies characterizing the population affected by the disease in Brazil. Characteristics related to management, diet and owner’s profile can influence the manifestation of the disease. The aim of the present study was to evaluate the association of clinical, haematological, biochemical, urinary, hydroelectrolyte and acid-base parameters in male cats with urethral obstruction. In addition, the objective was to determine the causes of urethral obstruction in male cats admitted to the Veterinary Teaching Hospital of Federal University of Rio Grande do Sul. Twenty-eight cats diagnosed with urethral obstruction were included in the study between December 2015 and December 2016. Data regarding medical history and physical examination were obtained. Blood and urine were collected, and imaging tests were performed (abdominal radiography and ultrasonography). Complete blood count, serum chemistry, blood pH, gas and electrolyte, urinalysis and urine culture were performed. All patients were treated accordingly to a previous established protocol. The most common cause of urethral obstruction in this study was idiopathic cystitis, which occurred in more than 60% of cases, followed by urethral plugs and urinary tract infection. No diagnosis of urolithiasis was achieved which could be explained by factors like age, environment and life style of cats. Most of obstructed cats presented with multiple systemic clinical signs, as well as, metabolic, electrolyte and acid-base alterations. The main disorders found were azotemia, hyperlactatemia, metabolic acidosis, hyperkalemia and ionized hypocalcemia. Hypothermia, depressed mental status, bradycardia and dehydration were the clinical parameters with the greatest amount of associations with the metabolic alterations and can be considered as good predictors of metabolic disorders. On the other hand, lactate was not considered a good predictor of clinical and laboratory abnormalities in this study.

Made available in DSpace on 2016-12-08T16:24:14Z (GMT). No. of bitstreams: 1 PGCA12MA106.pdf: 7444114 bytes, checksum: 2547058845886ef40cf92c5b6a4e6867 (MD5) Previous issue date: 2012-03-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Newborn calves derived from in vitro fertilization (IVF) procedures often have difficulties to adapt to life ex utero, with high birth weights usually associated with high plasma fructose levels in some in vitro-produced calves. We hypothesize that the fructose metabolic pathway is active at birth, with the fructosemia levels being either detrimental or beneficial to animal survival depending on the respiratory function in the neonate. To investigate this hypothesis, four and five newborn calves derived from in vitro- and in vivo-produced embryos were evaluated for morpho-physiological and clinical normality at birth, and for subsequent signs adaptation to life ex utero in the first 24 h of life. At birth, animals were subjected to gene expression analyses for key enzymes in the fructose metabolic pathway and to the collection of fetal fluids and urine for fructose analysis. In addition, during the period between birth and 24 h of life, animals were evaluated for clinical signs, plasma concentrations of metabolic substrates, blood chemistry, hemogasometry, and hematologic parameters. Neonatal physical, clinical, and behavioral traits were compared with physiological, biochemical, metabolic, and molecular findings observed at birth and in the first 24 h of life for the determination of physiological alterations and relationships of biological significance between the experimental groups. In vitro-derived newborn calves were heavier and larger at birth, having lower respiratory rate and thermoregulatory response than in vivo-derived controls, with no significant differences in fructose, glucose and lactate levels between groups. Nevertheless, physiological and metabolic findings at birth, in general, were widely similar and normal between groups. However, during the first 24 h of life, IVF-derived calves showed physiological, metabolic, biochemical, hemogasometric, and hematologic features indicative of a lower adaptation to life ex utero, particularly in the first 4 to 6 h of life. The main differences indicated that larger animals, mainly the IVF-derived calves, had more difficulties to maintain plasma oxygen levels, likely due to a less efficient hematosis, with evidence of a metabolic shift and elevation of metabolic substrates (mostly lactate), and a trend for acidosis followed by a compensatory normalization of the acid-base balance, predominantly in the first 6 h of life. The physiological and metabolic role of fructose was apparent, but not conclusive / Neonatos bovinos derivados de fecundação in vitro (FIV) frequentemente apresentam dificuldades de adaptação à vida ex utero, estando o excesso de peso ao nascer associado a elevadas concentrações plasmáticas de frutose em alguns bezerros de FIV. A hipótese deste trabalho é que a via metabólica da frutose é ativa ao nascimento, podendo ser benéfica ou prejudicial à sobrevivência neonatal, dependendo da função respiratória do neonato. Para investigar esta hipótese, quatro neonatos bovinos derivados de embriões produzidos in vitro e cinco de embriões in vivo foram avaliados quanto à normalidade morfo-fisiológica e clínica ao nascimento, e quanto a sinais de adaptação ao ambiente extrauterino nas primeiras 24 h de vida. Ao nascimento, os animais foram submetidos à análise de expressão gênica de enzimas da via metabólica da frutose e à coleta de fluídos fetais e de urina para mensuração da frutose. Durante o período do parto até as 24 h de vida, foram avaliados os sinais clínicos, as concentrações plasmáticas de substratos metabólicos, a bioquímica sanguínea, a hemogasometria e o hemograma. As características físicas, clínicas e comportamentais dos neonatos foram comparadas aos parâmetros fisiológicos, bioquímicos, metabólicos e moleculares avaliados ao parto e nas primeiras 24 h de vida para a determinação de alterações fisiológicas e inter-relações de significância biológica entre os grupos experimentais. Os neonatos bovinos derivados de FIV foram mais pesados e maiores ao nascimento, apresentando uma menor frequência respiratória e uma menor resposta termoregulatória que animais SOV, não havendo diferenças nos níveis de frutose, glicose e lactato entre os grupos. Não obstante, os parâmetros fisiológicos e metabólicos ao nascimento foram, em geral, amplamente similares e normais entre os grupos experimentais. Porém, ao longo das primeiras 24 h, os neonatos de FIV apresentaram características fisiológicas, metabólicas, bioquímicas, hemogasométricas, e hematológicas indicativas de uma maior dificuldade de adaptação à vida ex utero, em especial nas primeiras 4 a 6 h após de vida. As principais diferenças indicaram que animais maiores, em especial os de FIV, apresentaram maior dificuldade para a manutenção da normóxia, por uma hematose menos eficiente, mudanças metabólicas e uma elevação de substratos metabólicos (principalmente o lactato), e uma tendência à acidose com normalização compensatória do balanço ácido-base, principalmente nas primeiras 6 h de vida. O papel fisiológico e metabólico da frutose foi aparente, mas não conclusivo

O objetivo deste estudo foi avaliar o comportamento eletroquímico e do distúrbio ácido-básico em atletas de alto rendimento durante o campeonato mundial de Karatê realizado pela WKO (World Karate Organization) em 2014. A amostra foi composta por 19 atletas do gênero masculino, com idade média de 34 ± 8 anos. Todos eles eram faixas pretas, e tinham mais de 5 anos de prática na modalidade. Foram realizadas coletas de sangue capilar da polpa digital dos dedos da mão em três momentos: repouso, 5 minutos após o combate e 10 minutos após combate (kumite). A amostra foi analisada utilizando o aparelho de gasometria GEM Premier 3000, utilizando os parâmetros pH, Na+, K+, Ca2+, lactato e HCO3−. Os valores relacionados ao distúrbio ácido-básico apresentaram diferenças estatísticas (p<0,05) na maioria dos momentos coletados. Os valores de lactato encontrados foram de 2,77 ± 0,97 mmol/L no repouso, 6,57 ± 2,1 para 5 minutos após e de 4,06 ± 1,55 para 10 minutos após o combate. Os dados coletados relativos aos marcadores eletrolíticos não apresentaram diferenças estatísticas em seus valores (p<0,05). Através dos dados levantados, conjecturamos que a modalidade pode ser caracterizada como exercício de alta intensidade e com predominância do sistema glicolítico. A análise do distúrbio ácido-básico é uma medida eficiente para auxiliar no controle das cargas de treinamento. / The objective of this study was to analyze the electrochemical and acid-base disorders in high performance athletes during the World Karate Championship hosted by the WKO (World Karate Organization) in 2014. In this study 19 male athletes were analyzed (age 34 ± 8), black belts and with over 5 years of experience in the sport. Capillary blood samples from the digital pulp of the finger were collected in three stages: rest, 5 minutes after and 10 minutes after fighting (kumite). The sample was analyzed using blood gas analyzer GEM Premier 3000, using the parameters pH, Na+, K+, Ca2+, lactate e HCO3−. The values related to acid-base disturbance presented statistical differences (p <0.05) in most of the collected moments. The lactate levels found were 2.77 ± 0.97mmol / L in rest, 6.57 ± 2.1 for 5 minutes after and 4.06 ± 1.55 for 10 minutes after combat. The samples collected for the electrolytic markers showed no statistical differences in their values (p <0.05). Through the data collected, we conjecture that the sport can be characterized as a high-intensity exercise and with a predominance of the glycolytic system. The analysis of acid-base disturbance is an efficient method to assist in the control of training loads.

O objetivo deste estudo foi avaliar o comportamento eletroquímico e do distúrbio ácido-básico em atletas de alto rendimento durante o campeonato mundial de Karatê realizado pela WKO (World Karate Organization) em 2014. A amostra foi composta por 19 atletas do gênero masculino, com idade média de 34 ± 8 anos. Todos eles eram faixas pretas, e tinham mais de 5 anos de prática na modalidade. Foram realizadas coletas de sangue capilar da polpa digital dos dedos da mão em três momentos: repouso, 5 minutos após o combate e 10 minutos após combate (kumite). A amostra foi analisada utilizando o aparelho de gasometria GEM Premier 3000, utilizando os parâmetros pH, Na+, K+, Ca2+, lactato e HCO3−. Os valores relacionados ao distúrbio ácido-básico apresentaram diferenças estatísticas (p<0,05) na maioria dos momentos coletados. Os valores de lactato encontrados foram de 2,77 ± 0,97 mmol/L no repouso, 6,57 ± 2,1 para 5 minutos após e de 4,06 ± 1,55 para 10 minutos após o combate. Os dados coletados relativos aos marcadores eletrolíticos não apresentaram diferenças estatísticas em seus valores (p<0,05). Através dos dados levantados, conjecturamos que a modalidade pode ser caracterizada como exercício de alta intensidade e com predominância do sistema glicolítico. A análise do distúrbio ácido-básico é uma medida eficiente para auxiliar no controle das cargas de treinamento. / The objective of this study was to analyze the electrochemical and acid-base disorders in high performance athletes during the World Karate Championship hosted by the WKO (World Karate Organization) in 2014. In this study 19 male athletes were analyzed (age 34 ± 8), black belts and with over 5 years of experience in the sport. Capillary blood samples from the digital pulp of the finger were collected in three stages: rest, 5 minutes after and 10 minutes after fighting (kumite). The sample was analyzed using blood gas analyzer GEM Premier 3000, using the parameters pH, Na+, K+, Ca2+, lactate e HCO3−. The values related to acid-base disturbance presented statistical differences (p <0.05) in most of the collected moments. The lactate levels found were 2.77 ± 0.97mmol / L in rest, 6.57 ± 2.1 for 5 minutes after and 4.06 ± 1.55 for 10 minutes after combat. The samples collected for the electrolytic markers showed no statistical differences in their values (p <0.05). Through the data collected, we conjecture that the sport can be characterized as a high-intensity exercise and with a predominance of the glycolytic system. The analysis of acid-base disturbance is an efficient method to assist in the control of training loads.

A obstrução uretral é uma condição clínica comum em gatos, caracterizada por alterações metabólicas e do equilíbrio hidroeletrolítico e ácido-básico que são potencialmente fatais. Dentre as causas de obstrução uretral, a cistite idiopática é a mais frequentemente observada em diversos estudos. Outras causas incluem urolitíase, tampões uretrais e infecção do trato urinário. Em muitos casos, os gatos encontram-se em estado crítico e a morte pode ocorrer em decorrência de alterações metabólicas, como estado urêmico avançado e hipercalemia. As principais alterações eletrolíticas e do equilíbrio ácido-básico relatadas são hipercalemia, acidose metabólica, hiponatremia e hipocalcemia ionizada. Embora a obstrução uretral seja muito frequente na rotina clínica, estudos para caracterizar a população de gatos acometida ainda são escassos no Brasil. Características relacionadas ao manejo, dieta e perfil dos tutores podem influenciar na manifestação da doença. Os objetivos do presente estudo foram avaliar os parâmetros clínicos e as alterações hematológicas, bioquímicas, urinárias, eletrolíticas e ácido-básicas presentes em gatos com obstrução uretral e a associação entre estas variáveis. Além disso, objetivou-se conhecer as principais causas de obstrução uretral nos gatos atendidos no Hospital de Clínicas Veterinárias da Universidade Federal do Rio Grande do Sul. Para isso, foram incluídos no estudo 28 gatos com diagnóstico de obstrução uretral no período de dezembro de 2015 a dezembro de 2016. Foram obtidos dados referentes ao histórico, exame físico, coletados sangue e urina, além da realização de exames de imagem (radiografia e ultrassonografia abdominal). Em todos os gatos foram realizados hemograma, bioquímica sérica, análise de pH, gases e eletrólitos sanguíneos, urinálise e urocultura. Após, todos os pacientes foram tratados de acordo com um protocolo pré-estabelecido. A causa mais comum de obstrução uretral neste estudo foi a cistite idiopática, que ocorreu em mais de 60% dos casos, seguida de tampões uretrais e infecção do trato urinário. Nenhum caso de urolitíase foi diagnosticado, o que pode ser explicado por fatores como idade, ambiente e estilo de vida dos animais. A maioria dos gatos obstruídos apresentou múltiplos sinais sistêmicos, assim como alterações metabólicas, eletrolíticas e do equilíbrio ácido-básico, principalmente azotemia, hiperlactatemia, acidose metabólica, hipercalemia e hipocalcemia ionizada. Hipotermia, depressão do estado mental, bradicardia e desidratação foram os parâmetros clínicos que tiveram maior quantidade de associação com as alterações metabólicas e podem ser considerados bons preditores clínicos destas desordens. Por outro lado, o lactato não foi considerado um bom preditor de alterações clínicas e laboratoriais neste estudo. / Urethral obstruction is a common and potentially life-threatening condition, characterized by severe metabolic, electrolyte and acid-base disturbances. Among the causes of urethral obstruction, idiopathic cystitis is the most frequent in several studies. Other causes include urolithiasis, urethral plugs and urinary tract infection. In many cases, cats are critically ill and death may occur due to metabolic alterations, such as advanced uremic status and hyperkalemia. The main electrolyte and acid-base balance disorders reported are hyperkalemia, metabolic acidosis, hyponatremia and ionized hypocalcemia. Although urethral obstruction is a very common condition, there are few studies characterizing the population affected by the disease in Brazil. Characteristics related to management, diet and owner’s profile can influence the manifestation of the disease. The aim of the present study was to evaluate the association of clinical, haematological, biochemical, urinary, hydroelectrolyte and acid-base parameters in male cats with urethral obstruction. In addition, the objective was to determine the causes of urethral obstruction in male cats admitted to the Veterinary Teaching Hospital of Federal University of Rio Grande do Sul. Twenty-eight cats diagnosed with urethral obstruction were included in the study between December 2015 and December 2016. Data regarding medical history and physical examination were obtained. Blood and urine were collected, and imaging tests were performed (abdominal radiography and ultrasonography). Complete blood count, serum chemistry, blood pH, gas and electrolyte, urinalysis and urine culture were performed. All patients were treated accordingly to a previous established protocol. The most common cause of urethral obstruction in this study was idiopathic cystitis, which occurred in more than 60% of cases, followed by urethral plugs and urinary tract infection. No diagnosis of urolithiasis was achieved which could be explained by factors like age, environment and life style of cats. Most of obstructed cats presented with multiple systemic clinical signs, as well as, metabolic, electrolyte and acid-base alterations. The main disorders found were azotemia, hyperlactatemia, metabolic acidosis, hyperkalemia and ionized hypocalcemia. Hypothermia, depressed mental status, bradycardia and dehydration were the clinical parameters with the greatest amount of associations with the metabolic alterations and can be considered as good predictors of metabolic disorders. On the other hand, lactate was not considered a good predictor of clinical and laboratory abnormalities in this study.

A despeito dos avanços instrumentais, as titulações continuam sendo largamente aplicadas em laboratórios de química analítica. Seu amplo uso está relacionado com a boa exatidão em aplicações bem estabelecidas e freqüente indicação como método de referência (p. ex., farmacopéias), equipamentos simples, comuns e de custo reduzido, consumo moderado de tempo e de reagentes. Entre as técnicas de titulação, destacam-se as potenciométricas (TP), empregadas universalmente para a quantificação de um ou mais componentes ácidos ou básicos em soluções aquosas ou não aquosas, possibilitando ainda determinar as constantes de dissociação de ácidos e de protonação de bases. Na análise de dados de TP são, via de regra, empregados os métodos clássicos (derivadas), porém, para sistemas compreendendo componentes multiprotonáveis, as inflexões das curvas de titulação deixam ser nítidas, especialmente em baixas concentrações. Nestas condições desfavoráveis, ainda assim podem-se obter resultados satisfatórios recorrendo a métodos de linearização das curvas ou analisando os dados por regressão não linear (RNL), facilmente implementáveis em computadores, hoje disseminados nos laboratórios. Outra técnica clássica para acompanhamento de titulações é a condutimétrica (TC), menos utilizada que a TP nos dias atuais, salvo para ácidos ou bases muito fracas, servindo para prover dados complementares em estudos de formação de complexos ou na caracterização de amostras ambientais. Tipicamente os pontos estequiométricos coincidem com a intersecção de segmentos de reta. Para amostras muito diluídas, com sistemas multipróticos ou com elevada concentração de eletrólitos em relação às espécies tituladas, a interpretação gráfica fica dificultada e a precisão decai. Pesquisas recentes mostraram que é possível aproveitar informações obtidas por TP para alimentar modelos de regressão não linear de TC e, assim, obter informações mais completas das amostras estudadas. No presente trabalho, avançou-se nesta linha criando programas computacionais para a análise simultânea de dados obtidos por TC e TP, empregando o método de RNL e minimizando os desvios (ou o quadrado dos desvios) dos dois conjuntos completos de dados para prover caracterização mais completa das amostras e melhoria na precisão dos resultados. Um programa de simulação de dados de TC e TP das mais diversas combinações e concentrações de sistemas ácido-base, com recursos para acrescentar erros aleatórios às variáveis simuladas, foi também desenvolvido. Permitiu verificar a validade e potencialidade do método da TPC-RNL e aperfeiçoar o programa de análise simultânea de dados. O programa de TPC-RNL foi aplicado inicialmente à re-avaliação de dados de titulações de água de chuva anteriormente coletadas e analisadas por outro colaborador do grupo. Como exemplo de aplicação original a amostras reais difíceis tanto para a TC como a TP isoladamente, determinou-se, por TPC, baixas concentrações de ácidos orgânicos de baixo peso molecular em amostras obtidas do produto de oxidação acelerada do biodiesel. Os resultados se mostraram compatíveis com os obtidos por outro pesquisador que recorreu à eletroforese capilar, sendo que o pH, a condutividade e a força iônica das amostras também foi reproduzida pelo programa Peak Master alimentado com as concentrações ajustadas por RNL / Despite all the advances in instrumental techniques, titrations are still widely applied in analytical chemistry laboratories. Its widespread use is associated with good accuracy, well established applications, simple, readily available and low cost equipment, moderate consumption of time and reagents and frequent indication as a reference method (eg., Pharmacopoeias). Potentiometric titrations (PT) outstands among other techniques, being universally used for the quantification of one or more basic or acidic components in aqueous or non aqueous samples and enabling further determination of the dissociation constants of acids and bases. Data analysis of PT with the glass electrode is typically done by finding the inflections of the curves with help of simple derivatives. However, PT curves of systems with multiprotonable components, specially at very low concentrations, fail to show sharp inflections. Under such unfavorable conditions, satisfactory results can still be obtained by using curve linearization methods or nonlinear regression (NLR) methods, now at the reach of every laboratory computer. Another classic technique for following titrations is conductivity (CT), less used routinely than PT nowadays except for very weak acids or bases, but still valuable as a complementary technique in equilibrium studies of complex formation or for the characterization of environmental samples. The stoichiometric points of simple CTs are found at the intersection of line segments. For very dilute samples or for multiprotic systems or with high concentrations of electrolytes compared to the species to be titrated, the graphical interpretation becomes difficult and the accuracy declines. Recent research has shown that it is possible to harness information obtained by PT to render non-linear regression models of CT solvable, thus extracting more complete information of the samples. This dissertation is devoted to the development and evaluation of software for the simultaneous analysis of data from CT and PT gathered together in the laboratory or by simulation, using the method of NLR with minimization of the weighted deviations (or their squares) of the two full data sets to provide more complete characterization of the samples and to improve the precision of the results. A simulation program for generating CT and PT curves for freely combined acid-base systems over a wide concentration range, with features to add random errors to the simulated variables was also developed. The simulator was used to evaluate the validity and potentiality of the PCTNLR method and improve the software of simultaneous data analysis. The program of PCT-NLR was applied firstly to the re-evaluation of data from titrations of rainwater collected and analyzed previously by another contributor to the group. As an original application example to real samples that are difficult for CT or PT separately, low concentrations of organic acids of low molecular weight were determined by PCT-NLR in samples from accelerated biodiesel oxidation tests. The results were consistent with those obtained by another researcher who used the capillary electrophoresis. The pH, ionic strength and conductivity of the samples were also reproduced by the program Peak Master using concentrations adjusted by NLR