Mathematical models elaborated for removal of microconstituents (MCs) in activated sludge (AS) system have not incorporated developments in International Water Association (IWA) models. In this thesis, sorption and biodegradation kinetic models that can be applied to describe transformation of MCs in an AS process were evaluated (volatilization and photodegradation were considered negligible). Bisphenol-A (BPA), 17α-ethinylestradiol (EE2), and triclosan (TCS) have been selected as target compounds in this thesis. Sorption batch tests were conducted to retrieve kinetic and equilibrium data. Nine lab-scale continuous flow porous-pot bioreactors operating at various solids retention times (SRTs) and hydraulic retention times (HRTs) were studied for biodegradation of MCs. The effects of SRT, HRT and the biomass concentration on sorption and removal of MCs were also investigated and the results of each phase were incorporated into MCs fate models. Freundlich and linear sorption isotherms and pseudo-second-order kinetic models with different kinetic rates were found to best fit the sorption and desorption results. The result of biodegradation study in the presence of 20 µg/L of MCs demonstrated 90-98, 63-91 and 97-98% mean removal rates of BPA, EE2 and TCS, respectively, in systems operating at SRT of 5–15 d and HRT of 4-10 h. Calculation of mass fluxes of selected MCs in the dissolved and particulate phases showed that biotransformation was the principal removal mechanism of targeted MCs. The fate models for the degradation mechanism of selected MCs were evaluated by applying various mathematical models. The pseudo-second-order model was found to best fit the results when active MCs degraders (XC) were used in the model. It was found that biodegradation studies should incorporate XC and not mixed liquor suspended solids concentration in their kinetic formulations. Therefore, the result of this study could be seen in the context, where the active MCs degraders are proposed to reduce the variability of biodegradation kinetic rates in AS systems operating at different operational conditions. Finally nitrification inhibitors, allylthiourea (ATU) were added to reactors and it was found that although nitrification process affects the fate of MCs in AS system, heterotrophs were most likely responsible for the biotransformation of the targeted MCs.

Polymeric materials are increasingly being used in diverse, very demanding applications. Either pre- or post- application environments may require exposures to conditions hostile to the polymer's integrity. Frequently, these demanding conditions result in degradation of the polymer and subsequent decreases in desirable properties. Clearly then, a methodology to predict important properties, such as Tg, molecular weight, and tensile strength, from knowledge of the environmental history of a polymeric-based specimen is beneficial. The current study focuses on bisphenol A polycarbonate and tracks changes in the properties of this material as a function of the degree of degradation, t. For the purposes of the present research, the environmental effects have been limited to those associated with elevated temperature, although the methodology is general. This t parameter is a product of the kinetic rate constant, k, found from isothermal kinetics, and the time of degradation, t. Elucidation of t has been linked to measurement of the molecular weight distribution which in turn can be related to various properties to yield predictive relationships for these properties. Only the thermal history of the polymer and its initial properties are required for the model. This technique is not limited to a specific polymer or even to thermal degradation. As long as the kinetics of the process can be mathematically modeled, this approach should apply to a host of other situations, providing property prediction simply from knowledge of the material history. The research seeks to better understand the thermal degradation of polycarbonate. Kinetics of the process was explored, and the chemical mechanisms were examined. A key part of the project was the determination of the molecular weights and molecular weight distributions at each level of degradation. Furthermore, mechanical stress-strain properties, glass transition temperatures, and melt viscosities were also measured. This information, together with the kinetic expressions, facilitated prediction of these types of material properties for a known thermal history. / Ph. D.

ABSTRACT Isopropyl Alcohol (denoted as IPA) is a valuable chemical product, which is used in the chemical industry such as synthetic resin, essential oils and surface paint. Moreover, factory of the production of photography and electronics are also the user of IPA.IPA is the typical pollutant emitted from those industrial processing . It is known to be causing severe irritation and burns and is suspected to have long-term effects such as bronchitis. This study was to investigate the effect on conversion, deactivation of long-term test, selectivity of product and kinetics in oxidation of IPA over Cu and Cu/Ce catalysts supported on ceramic honeycomb. The explanation of results can be divided into several major parts as follows: 1. In the of selection catalyst, we find that 20%Cu/Ce catalysts prepared by wet- impregnation has the best conversion and selectivity. 2. The conversion of IPA in catalytic reaction is increased with the increasing both of reaction temperature and influent concentration of oxygen but decreased with the going up of initial concentration of IPA, space velocity and relative humidity. 3. In the catalyst stability of long-term test, Cu/Ce catalysts had a good stability after 7 days reaction in heterogeneous reactor. The tests such as XRD, SEM and EA were also determined to verify the stability from surface of catalyst. 4. Two kinetic models, Power rate law and Mars-Van Krevelen model were used to fit the kinetic data of the decomposition of IPA. Power rate law is suitable to describe the catalytic decomposition of IPA under the operation range in this work.

A presente discussão e uma extensão do modelo de cinética pontual de nêutrons, onde a reatividade e decomposta em termos de contribuição de curtas e longas escalas de tempo. A primeira representa o controle operacional do reator, enquanto a segunda e devido a alteração da composição química do combustível nuclear, como consequência do burn-up. E um primeiro passo em uma nova direção, uma vez que considera os efeitos dos principais venenos na cinética de nêutrons, ou seja, Xenônio-135 e Sam ario-149. O modelo proposto consiste em um sistema de equações não-lineares acoplado para a densidade de nêutrons, para os precursores de nêutrons atrasados e para as cadeias de decaimento dos venenos produtos de fissão. O sistema de equações e resolvido através de um método de decomposição, que expande os termos não-lineares em uma série infinita, obtendo um sistema recursivo, onde a inicialização da recursão e uma equação linear homogênea e os passos de recursão subsequentes consideram contribuições não-lineares como termo fonte constru dos em passos de recursão anteriores. A construção hierárquica do modelo também e realizada, onde graus espaciais de liberdade são considerados. São apresentados casos de estudos com várias estruturas temporais afim de mostrar a robustez da abordagem atual para este tipo de problema. / The present discussion is an extension to Neutron point kinetics models, where the reactivity is decomposed in a short and a long term contribution. The rst one represents operational reactor control, whereas the second one is due to the change of the chemical composition of the nuclear fuel as a consequence of burn-up. This is a rst step into a new direction where we consider only the e ects of the principal neutron poisons on neutron kinetics, i.e, Xenon-135 and Samarium-149. The proposed model consists in a system of coupled nonlinear equations for the neutron density, the delayed neutron precursors and the neutron poison decay chains. The equation system is solved using a decomposition method, which expands the non-linear terms in an in nit series, obtaining a recursive system, where the recursion initialization is a homogeneous linear equation and the subsequent recursion steps consider the non-linear contributions as source terms constructed from previous recursion steps. A hierarchical construction of the model is also performed, where spatial degrees of freedom are considered. We present case studies with severe time structure in order to show the robustness of the present approach for this kind of problems.

Made available in DSpace on 2016-12-23T14:02:51Z (GMT). No. of bitstreams: 1 Larissa Machado Alvarenga.pdf: 5166821 bytes, checksum: 9a52b626a19ffe6c666fd34df1f01780 (MD5) Previous issue date: 2013-09-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Muitos processos têm sido utilizados para a reciclagem dos resíduos de embalagens cartonadas. A pirólise se destaca como uma tecnologia promissora capaz de separar o alumínio do polietileno e gerar produtos com maior poder calorífico. Neste trabalho, realizou-se um estudo das reações de pirólise dos resíduos cartonados e de seus componentes puros, a fim de estimar os parâmetros cinéticos destas reações. Para isto, análises termogravimétricas isotérmicas e dinâmicas foram realizadas e dois diferentes tipos de modelos cinéticos foram utilizados: os isoconversionais e o das reações paralelas independentes (RPI). Os modelos isoconversionais permitiram calcular a energia de ativação global da reação de pirólise dos materiais, de acordo com as suas conversões. Os valores de energia de ativação obtidos com os modelos de Ozawa, K-A-S e Starink para a pirólise das embalagens cartonadas foram semelhantes (168,30; 166,54 e 166,78 kJ.mol-1), assim como aqueles encontrados para o polietileno (137,41; 132,49; 132,98 kJ.mol-1) e para o papel cartão (155,66; 153,46; 153,69 kJ.mol-1). Entretanto, o método de Kissinger estimou menores valores de energia de ativação para as embalagens cartonadas (121,42 kJ.mol-1) e para o papel cartão (144,89 kJ.mol-1), e um maior valor para a energia de ativação do polietileno (155,15 kJ.mol-1). O modelo RPI, por sua vez, permitiu calcular os parâmetros cinéticos de cada um dos subcomponentes da embalagem cartonada e do papel cartão. Os valores estimados para os parâmetros cinéticos dos subcomponentes dos materiais permaneceram dentro da faixa de valores encontrada na literatura. A perda de massa dos materiais simulada com o modelo RPI apresentou um bom ajuste aos dados experimentais obtidos por termogravimetria, com valores de desvios na mesma ordem de grandeza daqueles encontrados em outros trabalhos na literatura. Foi realizada ainda, uma análise de sensibilidade paramétrica do modelo RPI, através da qual se pode verificar que a energia de ativação afetou a conversão total dos materiais de forma mais acentuada do que o fator pré-exponencial. Em geral, este trabalho contribuiu na avaliação da qualidade dos ajustes dos modelos cinéticos utilizados e para o cálculo dos parâmetros cinéticos da pirólise dos materiais / Many processes have been used for recycling of carton packaging wastes. The pyrolysis highlights as a promising technology to be used for recovering the aluminum from polyethylene and generating products with high heating value. In this research, a study on pyrolysis reactions of carton packaging wastes and its pure components was performed in order to estimate the kinetic parameters of these reactions. For this, dynamic and isothermal thermogravimetric analyses were carried out and two different kinds of kinetic models were used: the isoconversional and Independent Parallel Reactions (IPR). Isoconversional models allowed to calculate the overall activation energy of the material pyrolysis reaction, in according to their conversions. The activation energy values obtained with Ozawa, KAS and Starink models for carton packaging pyrolysis were similar (168.30, 166.54 and 166.78 kJ.mol-1), as well as the results found for polyethylene (137.41, 132.49, 132.98 kJ.mol-1) and cardboard (155.66, 153.46, 153.69 kJ.mol-1). Nevertheless, the Kissinger method the method of Kissinger estimated lower values of activation energy for carton packaging (121.42 kJ.mol-1) and cardboard (144.89 kJ.mol-1), and a higher value for polyethylene activation energy (155.15 kJ.mol-1). The IPR model, in turn, allowed the calculation of kinetic parameters of each one of the carton packaging and paperboard subcomponents. The estimated values for the kinetic parameters of the material subcomponents were within the range of values found in the literature. The mass loss of materials simulated with the RPI model showed a good fit to the experimental data obtained by thermogravimetry, presenting deviation values in the same order of magnitude as those found in other literature studies. It was also performed a parametric sensitivity analysis of IPR model, that shown that the activation energy affected the total conversion of the material more strongly than the pre-exponential factor. In general, this work contributed to the quality evaluation of the kinetic models adjustment and for the calculation of the kinetic parameters of material pyrolysis

Made available in DSpace on 2017-07-10T17:36:57Z (GMT). No. of bitstreams: 1 2013_Diss_Leonardo_StreyProt.pdf: 1886831 bytes, checksum: f0eb61d130d6fa0e5a0fa7362ee15fa8 (MD5) Previous issue date: 2013-08-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work proposes the use of the bark of Pinus elliottii, a residue of wood processing, as biosorbent in the removal of metal ions Cd2+, Pb2+ and Cr3+solutions fortified, as an alternative to conventional treatment methods, such as precipitation, ion exchange, electrochemical treatment, flocculation and filtration. The biosorbent was characterized by scanning electron microscopy (SEM), infrared spectroscopy (FT-IR) and point of zero charge (pHPCZ). Adsorption tests were performed aiming to determine the optimal conditions of pH, mass of adsorbent and contact time for the adsorption process. The adsorption kinetics was evaluated by pseudofirst and pseudosecond order models, Elovich and intraparticle diffusion. Adsorption isotherms for each metal were constructed, which were linearized according to mathematical models of Langmuir, Freundlich and Dubinin-Radusckevich. To compare this biosorbent with a commercial adsorbent, comparative studies with activated charcoal were performed . Furthermore, we evaluated the ability of desorption of materials and the influence of temperature on adsorption of metals studied by pine bark. The characterization of the biosorbent by SEM showed a rough and heterogeneous surface, important adsorption characteristics. From the FT-IR was identified compounds such as lignin, cellulose and hemicellulose, which favor the adsorption process. The pHPZC obtained was 3.5. The mass tests showed that 8 g L-1 biosorbent are sufficient for efficient removal of metal ions in solution. From the tests of pH, optimum conditions were obtained: 7.0 for Cd and 5.0 to Pb and Cr. The equilibrium time for adsorptive process were 40, 20 and 80 min for Cd, Pb and Cr, respectively. With the application of kinetic models is possible to suggest that the main limiting step for adsorption of these metal ions may be the chemisorption. The mathematical models that best fitted for the adsorption pine bark were Dubinin-Radushkevich for Cd, Freundlich for Pb, and Langmuir and Freundlich for Cr. The increase in temperature increased removal efficiency and, furthermore, with the thermodynamic parameters, it was found that the adsorption process is controlled by chemisorption. Desorption values were low, indicating a strong interaction of the metal with the surface of the adsorbent. In comparative studies with activated coal its possible to concluded that, despite the bark of Pinus elliottii present an adsorption efficiency less than this, the same satisfactory results of adsorption and removal of metal ions present in solutions fortified. Thus, it is concluded that the use of the bark of Pinus elliottii as biosorbents showed a promising alternative for the decontamination of contaminated water bodies by metal ions Cd, Pb and Cr / O presente trabalho propõe a utilização da casca de Pinus elliottii, um resíduo do beneficiamento da madeira, como biossorvente na remoção dos íons metálicos Cd2+, Pb2+ e Cr3+ de meio aquoso, como alternativa aos métodos convencionais de tratamento, como a precipitação, troca iônica, tratamento eletroquímico, floculação e filtração. O biossorvente foi caracterizado por meio de microscopia eletrônica de varredura (MEV), espectroscopia na região do infravermelho (FT-IR) e ponto de carga zero (pHPCZ). Após a caracterização foram realizados testes de adsorção objetivando determinar as condições ideais de pH, massa de adsorvente e tempo de contato para o processo de adsorção. A cinética de adsorção foi avaliada pelos modelos de pseudoprimeira ordem, pseudossegunda ordem, Elovich e difusão intrapartícula. Foram construídas as isotermas de adsorção para cada metal, as quais foram linearizadas conforme os modelos matemáticos de Langmuir, Freundlich e Dubinin-Radusckevich. Visando comparar este biossorvente com um adsorvente comercial, foram realizados estudos comparativos com o carvão ativado. Além disso, foram avaliados a capacidade de dessorção dos materiais e a influência da temperatura no processo de adsorção dos metais em estudo pela casca de pinus. A caracterização do biossorvente por meio da técnica de MEV mostrou uma superfície irregular e heterogênea, importantes características de adsorção. A partir da FT-IR foi possível identificar grupos funcionais comuns a estrutura da lignina, celulose e hemicelulose, os quais favorecem o processo de adsorção. O pHPCZ obtido foi de 3,5. Os testes de massa demonstraram que 8 g L-1 do biossorvente são suficientes para uma remoção eficiente dos íons metálicos em solução. A partir dos testes de pH, as condições ideais obtidas foram: 7,0 para Cd e, 5,0 para Pb e Cr. Os tempos de equilíbrio para o processo adsortivo foram 40, 20 e 80 min, para Cd, Pb e Cr, respectivamente. Com a aplicação dos modelos cinéticos sugere-se que a etapa limitante para a adsorção destes íons metálicos pode ser a quimiossorção. Os modelos matemáticos que melhor se ajustaram para a adsorção em casca de pinus foram Dubinin-Radushkevich para o Cd, Freundlich para Pb e, Langmuir e Freundlich para o Cr. O incremento na temperatura aumentou eficiência de remoção e, além disso, com os parâmetros termodinâmicos, concluiu-se que o processo de adsorção é controlado pela quimissorção. Os valores de dessorção foram baixos, indicando uma forte interação dos metais com a superfície do adsorvente. Com os estudos comparativos com o carvão ativado foi possível concluir que apesar da casca de Pinus elliottii apresentar uma eficiência de adsorção menor que este, a mesma apresentou resultados satisfatórios de adsorção e remoção dos íons metálicos presentes nas soluções fortificadas. Assim, conclui-se que a utilização da casca de Pinus elliottii como biossorvente mostrou-se uma alternativa promissora para descontaminação de corpos hídricos contaminados pelos íons metálicos Cd, Pb e Cr

<p>Equilibrium isotherms and the adsorption kinetics of heavy metals onto chitosan were studied experimentally. Chitosan, a biopolymer produced from crustacean shells, has applications in various areas, particularly in drinking water and wastewater treatment due to its ability to remove metallic ions from solutions. The adsorption capacity of chitosan depends on a number of parameters: deacetylation degree, molecular weight, particle size and crystallinity. The purpose of this work was to study the adsorption of copper, zinc, mercury, and arsenic on chitosan produced from shrimp shells at a laboratory level.</p><p>The experimental work involved the determination of the adsorption isotherms for each metallic ion in a batch system. The resulting isotherms were fitted using the Langmuir model and the parameters of the equation were determined. Kinetic studies of adsorption for different metallic ions at different concentrations and with different particle sizes were performed in batch and column systems. Simplified models such as pseudo-first-order, pseudo-second-order, and intra-particle diffusion equations were used to determine the rate-controlling step. Some preliminary studies were carried out to address the application of chitosan as an adsorbent in the removal of heavy metals or other metallic ions from natural water and wastewater. The regeneration of chitosan was also studied.</p><p>The results showed that the adsorption capacity depends strongly on pH and on the species of metallic ions in the solution. The optimum pH value for the metallic cation adsorption was between 4 and 6, whereas for arsenic adsorption it was about 3. When the pH is not controlled, the adsorption capacity is independent of the initial pH with the solution reaching a final pH of about 7. It was also found that the Langmuir equation described very well the experimental adsorption data for each metallic ion. The adsorption capacity for the metals on chitosan follows the sequence Hg>Cu>Zn>As.</p><p>The study of the adsorption kinetics of these metallic ions shows that the particle size has a significant influence on the metal uptake rate for copper; but that it has only a slight influence on the adsorption rate of zinc and mercury in the range studied. Arsenic adsorption exhibited an interesting behaviour which depends strongly on the pH of the solution; the uptake increased at short adsorption times and then decreased at long times. The analysis of kinetic models showed that the pseudo-second-order adsorption mechanism is predominant, and the overall rate of the metallic ion adsorption process is therefore controlled by adsorption reactions and not by mass transfer for the range of particle sizes examined in this study.</p><p>With regard to the regeneration of chitosan, it was found that sodium hydroxide is a good agent for zinc and arsenic desorption, whereas ammonium sulphate and sodium chloride were the most suitable for copper and mercury desorption, respectively. The ability of chitosan to remove arsenic from natural water, and copper and zinc from mining waste water was verified. The use of these results for designing purposes is a subject for future work.</p>

No description available.

We have designed and engineered bi-catalyst magnesium hydride composites with superior sorption performance to that of ball milled magnesium hydride catalyzed with the individual baseline catalysts. We have examined the effect of single-walled carbon nanotube (SWCNT)-metallic nanoparticle additions on the hydrogen desorption behavior of MgH2 after high-energy co-milling. We showed the synergy between SWCNT's and metallic nanoparticles in catalyzing the sorption of magnesium hydride. The optimum microstructure for sorption, obtained after 1 h of co-milling, consists of highly defective SWCNTs in intimate contact with metallic nanoparticles and with the hydride. This microstructure is optimum, presumably because of the dense and uniform coverage of the defective SWCNTs on the MgH2 surface. Cryo-stage transmission electron microscopy (TEM) analysis of the hydride powders revealed that they are nanocrystalline and in some cases multiply twinned. Since defects are an integral component of hydride-to-metal phase transformations, such analysis sheds new insight regarding the fundamental microstructural origins of the sorption enhancement due to mechanical milling. The nanocomposite shows markedly improved cycling as well. Activation energy analysis demonstrates that any catalytic effect due to the metallic nanoparticles is lost during cycling. Improved cycling performance is instead achieved as a result of the carbon allotropes preventing MgH2 particle agglomeration and sintering. The nanocomposite received over 100 sorption cycles with fairly minor kinetic degradation. We investigated the catalytic effect of Fe + Ti bi-metallic catalyst on the desorption kinetics of magnesium hydride. Sub-micron dimensions for MgH2 particles and excellent nanoscale catalyst dispersion was achieved by high-energy milling. The composites containing Fe shows DSC desorption temperature of 170 °C lower than as-received MgH2 powder, which makes it suitable to be cycled at relatively low temperature of 250 °C. The low cycling temperature also prevents the formation of Mg2FeH6. The ternary Mg-Fe-Ti composite shows best performance when compared to baseline ball milled magnesium hydride with only one catalytic addition. With a very high BET surface area it also shows much less degradation during cycling. The synergy between Fe and Ti is demonstrated through use of TEM and by carefully measuring the activation energies of the baseline and the ternary composites. / Materials Engineering

Laktatkonzentrationszeitkurven nach akuter körperlicher Belastung und im Stufentest haben sich ebenso wie der Dauerleistungstest in der sportwissenschaftlichen Leistungsdiagnostik etabliert. Beide Verfahren erlauben, die Leistungsfähigkeit von Sportlern einzuschätzen und die Trainingsbelastung optimal entsprechend der Sportdisziplin zu steuern. Der Unterarm-Ischämie-Test dient dazu, Muskelerkrankungen auf der Basis von Laktat- und Ammoniakkonzentration zu differenzieren. Die Laktat-Konzentrations-Zeitkurven nach akuter Belastung, im Stufentest oder im Dauerleistungstest sowie im Unterarm-Ischämietest werden vorwiegend deskriptiv durch Parameter wie die maximale Laktatkonzentration oder Leistung bei bestimmter Laktatkonzentration ausgewertet. Das Ziel der vorliegenden Untersuchung ist, pharmakokinetische Modelle für auf der Laktatkonzentration basierende Tests zu prüfen und deren praktische Relevanz zu diskutieren. Dabei können der akute Belastungstest und der Vorderarm-Ischämietest wegen eines ähnlichen Laktatprofils (Peak-Kurven), der Dauerleistungstest (kumulative Kurven) und der Stufentest (stetig monoton steigende Kurven) getrennt betrachtet werden. Die Routinelaktatprofile von 13 männlichen Freizeitsportlern (Alter: 20-35 Jahre), die sich einem 3 Minuten dauernden akuten ergometrischen Leistungstest unterzogen, wurden zur Modellbildung herangezogen. Der Unterarm-Ischämietest wurde bei acht Patienten im Alter zwischen 20 und 45 Jahren, bei denen bei Aufnahme die Verdachtsdiagnose einer Muskelerkrankung des Glukose- oder Eiweißstoffwechsels bestand, durchgeführt. Wird die Laktatkonzentrationszeitkurve, oder im Ischämietest auch der Ammoniakkonzentrationzeitkurve, als Summe eines Produktions- und Eliminationsvorgangs, dagestellt, lassen sich zusätzliche Informationen gewinnen. Blutlaktatkonzentrationen (Cb(t)) nach akuter ergometrischer Belastung wurden mittels nichtlinearer Regression an das Grundmodell Cb(t)=Co+B*(exp(-Lp*t )-exp(-Le*t)) angepasst, wobei Co der Ruhelaktatkonzentration und B einer Konstanten entsprechen. Die Laktatproduktionsrate (Lp) und Laktateliminationsrate (Le) differenzieren zwischen der Laktatproduktion einerseits und der Laktatelimination andererseits. Der Quotient Lp/P (P=erbrachte Leistung) stellt ein standardisiertes Maß für die Laktatproduktion im Muskel dar. Dagegen charakterisiert der Quotient Le/P die Elimination des Laktats aus dem Blutkompartiment. Über die Beziehung HWZp = ln2/Lp und HWZe = ln2/Le können die entsprechenden Halbwertszeiten berechnet werden. Eine reine Laktatproduktionszeitkurve (Cp(t)) lässt sich über die Beziehung Cp(t) = Cb(t) + Le*( ∫Cb(t)-Co*t) rekonstruieren und zeigt anschaulich den Verlauf der Laktatproduktion. Die Produktionszeitkurve erreicht im Verlauf der Elimination asymptotisch einen Maximalwert (Pm) und kann, identische Verteilungsvolumina des Laktats (Vdl) vorausgesetzt, über die Beziehung Ml = Vdl * Pm Informationen über die insgesamt freigesetzte Laktatmenge (Ml) geben. 19 gesunde Probanden unterzogen sich einem standardisierten Stufentest unter folgenden Bedingungen: Vor Beginn der Bergtour (Meereshöhe, SLa), nach Ankunft auf 1700 m (1700a), nach 10tägigem moderaten Training (Bergwandern zwischen 1700 und 3000m, 6 h pro Tag) auf 1700 m (1700b) sowie nach 4 Wochen (kein spezifisches Training) erneut auf Meereshöhe (SLb). Primäres Ziel der Auswertung war, mit der Potenzfunktion der allgemeinen Form Y(x) = A+ B * X^C den funktionalen Zusammenhang zwischen Laktatkonzentration und Belastung bzw. Herzfrequenz und Belastung zu beschreiben. Neben den modellabhängigen Faktoren (Ordinatenabschnitt, Steigungsfaktor, Exponent) ließen sich durch die AUC(70-280) (Area under the curve 70 bis 280 Watt Leistung) das Ausmaß der Laktatproduktion, die entsprechende mittlere Konzentration (Cm) und durch die Laktatkonzentrationen bei 70 und 280 Watt (LT-70, LT-280) der Laktatanstieg charakterisieren. Der Dauerleistungstest hat sich neben dem akuten ergometrischen Belastungstest in der sportmedizinischen Leistungsdiagnostik als Methode etabliert. Bisher konzentrierte sich die Auswertung auf die maximalen Blutlaktatkonzentrationen im steady state. Die Autoren schlagen verschiedene Modelle vor, sowohl empirische als auch mechanistische, um die Laktatkonzentrationszeitkurve im Dauerleistungstest zu beschreiben. Neben der maximalen Konzentration können nach Berechnung der Modellkurven durch nichtlineare Regression Konzentrationen zu definierten Bedingungen (z. B. LT20 = Laktat nach 20 Minuten) oder die Steigung der Kurve beurteilt werden. Darüber hinaus lässt sich die AUC (Area under the curve) als Ausmaß für die Laktatbildung während des Dauerleistungstests mit der Trapezregel bestimmen. Zusammenfassend zeigen die Untersuchungen, dass in allen Verfahren der Laktatdiagnostik, dem akuten Belastungstest, der Standardergometrie, dem Laktatischämietest und dem Dauerleistungstest, signifikante und praktikable pharmakokinetische Modelle berechnet werden können. Sie erlauben es, die Ergebnisse mittels Modellparametern zu quantifizieren und zu vergleichen. / Lactate concentration versus time curves following acute physical exercise, the standard exercise test using increasing levels of work load and the steady state exercise test have been established methods to characterise the fitness of athletes and to control training intensity. The ischemic forearm exercise test (IFET) is used to detect metabolic disorders of muscles based on lactate and ammonia concentration during exercise under ischemia. Lactate concentration curves following acute exercise, standard ergometries and steady state tests as well as IFET are generally analysed descriptively, i. e. maximum lactate concentrations or work load with regard to defined lactate concentrations are used. The primary objective of this study was to assess pharmacokinetic models for lactate in exercise tests and to discuss the relevance in sports science. For practical purpose, the models used in acute and IFET (asymmetric peak curves), the steady state exercise test (cumulative curves) and standard exercise tests (continuously increasing function) are dealt with separately. Routine lactate profiles of 13 male nonprofessional athletes (age: 20-35) years who underwent an acute ergometry lasting 3 minutes were used to assess different pharmacokinetic models. An IFET was performed in 8 patients (Age: 20-45 years) supposed to have disorders of glucose metabolism or lack of myoadenylate deaminase. Lactate concentration versus time curves were fitted by means of non-linear regression to different kinetic models. The modified basic curve Cb(t)=Co+B*(exp(-Lp*t )-exp(-Le*t)), where Cb denotes the baseline concentration, B a constant, Le denotes the lactate elimination constant and Lp the “absorption or production” constant, yielded remarkable nonlinear regression results in for both test settings. Lactate concentration versus time curves in acute exercise tests are mostly assessed descriptively by means of parameters such as maximum concentration or workload with regard to specified lactate levels. Additional diagnostic information can be obtained, if production and elimination processes of the concentration versus time curve are separated. Production rate (Lp) and elimination rate (Le) of lactate are to define the shape of the curve. The ratio Lp/P (P=performance, work load), where Lp denotes the workload of the ergometer, can be considered as a standardized criterion of lactate production in the muscle. On the contrary, the ratio Le/P characterizes the elimination process from the vascular compartment. The corresponding half-lives [Tp, Te] are obtained using the relations Tp = ln2/Lp and Te = ln2/Le. The absolute lactate production versus time curve [Cp(t)] is given by the following equation: Cp(t) = Cb(t) + Le*( ∫Cb(t)-Co*t). The production versus time curve reaches a maximum value (Pm) after termination of the elimination process. If lactate has identical volumes of distribution (Vdl), Pm characterizes the total amount of lactate production (Ml) due to the relation Ml = Vdl*Pm. Nineteen healthy volunteers were exposed to a standardized exercise test at sea level (SLa), at an altitude of 1700 m before (1700a) and after a moderate 10 day mountain training (1700b), with a final control four weeks later at sea level (SLb). Vital signs, blood lactate and arterial oxygen saturation were determined prior, during or after the exercise test. The primary aim of the study was to fit the power function Y(X) = A+ B * X^C as a model for lactate versus workload and heart rate versus workload data. Apart from model characteristics (intercept, slope, exponent) the extent of lactate production could be estimated by the model independent characteristic AUC(70-280) (Area under the curve between 70 and 280 Watt) and the corresponding average concentration (Cm). The degree of lactate increase was characterized by means of the lactate concentration at 70 and 280 Watt (LT-70, LT-280), respectively. Apart from the standard and acute exercise test the steady state exercise test has gained increasing relevance in practice of sports medicine. So far, lactate curves of steady state tests were characterised by means of maximum. The author suggests several models, both empirical and mechanistic models, in order to fit lactate concentration versus time curves of the steady state ergometry. In addition to the maximum lactate concentration fitted nonlinear regression curves allow to assess the concentrations at defined conditions (e.g. LT20=lactate after 20 minutes of steady state workload, EC50 of the Emax model) or the slope of the curve. Moreover, the AUC(0-tx) – a measure for the extent of lactate production – can be calculated using the trapezoidal rule. In conclusion, in all lactate based tests, acute and standard ergometry, ischemic forearm test and steady state exercise test, concentration versus time data were fitted suitable pharmacokinetic models which allow to quantify and compare the results.