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Prediction of the skin sensitization potential of organic chemicals through in vitro bioassay and chemoassay informationZhang, Weicheng 16 March 2015 (has links) (PDF)
Skin sensitization resulting for allergic contact dermatitis (ACD) is an occupational and environmental health issue. The allergic hazard for workers and consumers is a serious problem for individuals, employers and marketing certain products. Consequently, it is necessary to accurately identify chemicals skin sensitization potential. According to the new EU chemical regulation REACH (Registration, Evaluation, Authorization and Restriction of Chemicals), information of skin sensitization of chemicals manufactured or imported at or above 1 ton/year should be available.
Currently, valid approaches assessing skin sensitization rely on animal testing, such as local lymph node assay (LLNA). However, it now ultimately eliminates using animals for this purpose. Based on the fact that a key step in the skin sensitization process is formatting a covalent adduct between allergic sensitizers and proteins and/or peptides in skin, a lot of additional approaches are proposed and developed for replacing or reducing animal used. In this research, three bioassays, 24 h growth inhibition toward Tetrahymena pyriformis, long term (24 h) and short term (30 min) bacterial toxicity (to Vibrio fischeri), and a kinetic glutathione chemoassay are applied for predicting the organic chemicals’ skin sensitization potential. The major results and conclusions obtained are listed as follows:
1. Toxicity enhancement (Te) of 55 chemicals comprising different sensitization potencies were determined and compared with their narcotic toxicity to predict their skin sensitization. Three linear regressions yielded for all allergic sensitizer without nonsensitizers for each bioassay. The linear regressions are improved after classifying sensitizers into five different reaction mechanistic domains. Correspondingly, five different slopes from various reaction mechanisms indicate a decreased sensitivity of toxicity enhancement to skin sensitization potential with order SNAr > SN2 > acylation ≈ Schiff base > aromatic Michael addition. Based on the fact that a key step in the skin sensitization process is forming a covalent adduct between allergic sensitizers and proteins and/or peptides, Te > 10 as a threshold is applied to discriminate these allergic sensitizers, with 100% accuracy for strong (with extreme) and weaker sensitizers, up to 72% accuracy for moderate sensitizers and less than 69% accuracy for nonsensitizers. Compared with these bioassays, a decreasing order of sensitivities is 24 h growth inhibition (Tetrahymena pyriformis) > 24 h growth inhibition (Vibrio fischeri) > 30 min bioluminescence inhibition (Vibrio fischeri). These three bioassays are useful tools for screening sensitization potency of allergic chemicals, and the toxicity enhancement (Te) can be used to discriminate sensitizers from weak or nonsensitizers. However, in this context we should separate aromatic from aliphatic Mas (Michael acceptors). Moreover, metabolic biotransformation should be considered during predicting nonsensitizers’ skin sensitization.
2. Chemical reactivity of selected 55 compounds measuring through kinetic glutathione chemoassay applies to predict their skin sensitization. This chemoassay confirms the fact that the key step of sensitizers eliciting skin sensitization is formatting a covalent adduct between sensitizers and skin proteins or peptides. The chemical reactivity of tested sensitizers strongly relates with their sensitization potential, with strong (extreme) sensitizers presenting the highest reactivity as followed with moderate sensitizers, weak sensitizers as well as nonsensitizers. Moreover, an integrated platform of this chemoassay data and three bioassays data is performed, and this performance shows good sensitivity for monitoring skin sensitization potency, with more rational accuracy for each sensitizing classifications.
3. Thiol reactivity (kGSH) as well as toxicity enhancement (Te) of additional 21 aliphatic α,β-unsaturated compounds are determined for predicting their skin sensitization potential. The linear regressions of skin sensitization versus thiol reactivity and skin sensitization versus toxicity enhancement are significantly improved after classifying these 21 compounds to four chemical subgroups (acrylates, other esters, ketones and aldehydes). Thiol reactivity of these subgroups presented different sensitivity to skin sensitization, with a decreasing order as acrylates (-2.05) > other esters (-1.26) > ketones (-0.43) > aldehydes (-0.21). Moreover, thiol reactivity is confirmed to be a more sensitive tool for predicting skin sensitization, compared with toxicity enhancement. Although the datasets are probably too small to give a definite decision, hydrophobicity reveals contribution to skin sensitization for aliphatic MAs, which is different with literature report. This study suggests that aliphatic MAs should be treated separately into different chemical subgroups for analysis, and their skin sensitization potency can be predicted using kinetic glutathione chemoassay as well as toxicity enhancement bioassay.
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Einfluss der Exposition mit flüchtigen organischen Verbindungen im Innenraum auf akute Bronchitis und allergische Erkrankungen von Kindern im 4. Lebensjahr – LISA-StudieHoffmann, Stefanie 08 April 2011 (has links)
Flüchtige organische Verbindungen (Volatile organic compounds (VOC)) sind ubiquitär vorkommende kohlenstoffhaltige Substanzen. Untersuchungen haben relevante VOC-Konzentrationen im Inneren von Gebäuden nachgewiesen. Da der Innenraum zum typischen Aufenthaltsort des modernen Menschen geworden ist, sind diese Schadstoffe in das Interesse der Forschung gerückt. Kinder reagieren unter Schadstoffexposition besonders sensibel, denn viele wichtige Organsysteme befinden sich noch in ihrer Entwicklung.
In der vorliegenden Arbeit wurden Leipziger Daten der LISA-Studie („Einfluss von Lebensbedingungen und Verhaltensweisen auf die Entwicklung von Immunsystem und Allergien im Ost-West-Vergleich“) hinsichtlich möglicher Effekte einer VOC-Exposition auf Erkrankungen der Kinder im 4. Lebensjahr analysiert. Bei der LISA-Studie handelt es sich um eine multizentrische prospektive Geburts-Kohortenstudie, in die von November 1997 bis Januar 1999 insgesamt 3097 gesunde und reife Neugeborene deutscher Herkunft mit einem Geburtsgewicht > 2500 g rekrutiert wurden. Die Berechnungen der vorliegenden Arbeit erfolgten mit VOC-Messwerten um den 3. Geburtstag der Kinder. Die jeweiligen logistischen Regressionsmodelle wurden auf das Geschlecht, die atopische Familienanamnese, eine passive Tabakrauchexposition, das Aufstellen neuer Möbel im Kinderzimmer, Renovierungen und die Erneuerung des Fußbodenbelags in der Wohnung adjustiert.
Es ließen sich VOC bestimmen, die bei Konzentrationserhöhungen eine erhöhte Chance für eine akute Bronchitis zur Folge hatten. Als Risikofaktor einer akuten Bronchitis ließ sich außerdem die Erneuerung des Fußbodenbelags in der Wohnung ermitteln. Während sich für eine akute Bronchitis in Abhängigkeit der VOC-Konzentration erstmals eine Dosis-Wirkungs-Kurve ableiten ließ, war dies für allergische Erkrankungen nicht möglich.
Weitere Untersuchungen sind notwendig um Pathomechanismen der VOC-Einwirkungen auf den kindlichen Organismus aufzuklären.
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Surface-Modified Phthalocyanine-Based Two-Dimensional Conjugated Metal–Organic Framework Films for Polarity-Selective Chemiresistive SensingWang, Mingchao, Zhang, Zhe, Zhong, Haixia, LI, Wei, Hambsch, Mike, Zhang, Panpan, Wang, Zhiyong, St. Petkov, Petko, Heine, Thomas, Mannsfeld, Stefan C. B., Feng, Xinliang, Dong, Renhao 03 November 2022 (has links)
Surface-modification of phthalocyanine-based two-dimensional conjugated metal-organic framework (2D c-MOF) films by grafting aliphatic alkyl chains is developed for achieving high-performance polarity-selective chemiresistive sensing toward humidity and polar alcohols.
2D conjugated metal–organic frameworks (2D c-MOFs) are emerging as electroactive materials for chemiresistive sensors, but selective sensing with fast response/recovery is a challenge. Phthalocyanine-based Ni2[MPc(NH)8] 2D c-MOF films are presented as active layers for polarity-selective chemiresisitors toward water and volatile organic compounds (VOCs). Surface-hydrophobic modification by grafting aliphatic alkyl chains on 2D c-MOF films decreases diffused analytes into the MOF backbone, resulting in a considerably accelerated recovery progress (from ca. 50 to ca. 10 s) during humidity sensing. Toward VOCs, the sensors deliver a polarity-selective response among alcohols but no signal for low-polarity aprotic hydrocarbons. The octadecyltrimethoxysilane-modified Ni2[MPc(NH)8] based sensor displays high-performance methanol sensing with fast response (36 s)/recovery (13 s) and a detection limit as low as 10 ppm, surpassing reported room-temperature chemiresistors.
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Surface-Modified Phthalocyanine-Based Two-Dimensional Conjugated Metal–Organic Framework Films for Polarity-Selective Chemiresistive SensingWang, Mingchao, Zhang, Zhe, Zhong, Haixia, Li, Wei, Hambsch, Mike, Zhang, Panpan, Wang, Zhiyong, St. Petkov, Petko, Heine, Thomas, Mannsfeld, Stefan C. B., Feng, Xinliang, Dong, Renhao 03 November 2022 (has links)
This corrigendum corrects an omission from the Acknowledgement section. The research leading to the results published in this manuscript was also supported by the project CALIPSOplus under Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020.
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Extension and application of a tropospheric aqueous phase chemical mechanism (CAPRAM) for aerosol and cloud models / Erweiterung und Anwendung eines troposphärischen Flüssigphasenchemiemechanismus (CAPRAM) für Aerosol- und WolkenmodelleBräuer, Peter 19 October 2015 (has links) (PDF)
The ubiquitous abundance of organic compounds in natural and anthorpogenically influenced eco-systems has put these compounds into the focus of atmospheric research. Organic compounds have an impact on air quality, climate, and human health. Moreover, they affect particle growth, secondary organic aerosol (SOA) formation, and the global radiation budget by altering particle properties. To investigate the multiphase chemistry of organic compounds and interactions with the aqueous phase in the troposphere, modelling can provide a useful tool.
The oxidation of larger organic molecules to the final product CO2 can involve a huge number of intermediate compounds and tens of thousands of reactions. Therefore, the creation of explicit mechanisms relies on automated mechanism construction. Estimation methods for the prediction of the kinetic data needed to describe the degradation of these intermediates are inevitable due to the infeasibility of an experimental determination of all necessary data. Current aqueous phase descriptions of organic chemistry lag behind the gas phase descriptions in atmospheric chemical mechanisms despite its importance for the multiphase chemistry of organic compounds.
In this dissertation, the gas phase mechanism Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) has been advanced by a protocol for the description of the oxidation of organic compounds in the aqueous phase. Therefore, a database with kinetic data of 465 aqueous phase hydroxyl radical and 129 aqueous phase nitrate radical reactions with organic compounds has been compiled and evaluated. The database was used to evaluate currently available estimation methods for the prediction of aqueous phase kinetic data of reactions of organic compounds. Among the investigated methods were correlations of gas and aqueous kinetic data, kinetic data of homologous series of various compound classes, reactivity comparisons of inorganic radical oxidants, Evans-Polanyi-type correlations, and structure-activity relationships (SARs). Evans-Polanyi-type correlations have been improved for the purpose of automated mechanism self-generation of mechanisms with large organic molecules. A protocol has been designed based on SARs for hydroxyl radical reactions and the improved Evans-Polanyi-type correlations for nitrate radical reactions with organic compounds. The protocol was assessed in a series of critical sensitivity studies, where uncertainties of critical parameters were investigated.
The advanced multiphase generator GECKO-A was used to generate mechanisms, which were applied in box model studies and validated against two sets of aerosol chamber experiments. Experiments differed by the initial compounds used (hexane and trimethylbenzene) and the experimental conditions (UV-C lights off/on and additional in-situ hydroxyl radical source no/yes). Reasonable to good agreement of the modelled and experimental results was achieved in these studies.
Finally, GECKO-A was used to create two new CAPRAM version, where, for the first time, branchingratios for different reaction pathways were introduced and the chemistry of compounds with up to four carbon atoms has been extended. The most detailed mechanism comprises 4174 compounds and 7145 processes. Detailed investigations were performed under real tropospheric conditions in urban and remote continental environments. Model results showed significant improvements, especially in regard to the formation of organic aerosol mass. Detailed investigations of concentration-time profiles and chemical fluxes refined the current knowledge of the multiphase processing of organic compounds in the troposphere, but also pointed at current limitations of the generator protocol, the mechanisms created, and current understanding of aqueous phase processes of organic compounds. / Das zahlreiche Vorkommen organischer Verbindungen in natürlichen und anthropogen beeinflussten Ökosystemen hat diese Verbindungen in den Fokus der Atmosphärenforschung gerückt. Organische Verbindungen beeinträchtigen die Luftqualität, die menschliche Gesundheit und das Klima. Weiterhin werden Partikelwachstum und -eigenschaften, sekundäre organische Partikelbildung und dadurch der globale Strahlungshaushalt durch sie beeinflusst. Um die troposphärische Multiphasenchemie organischer Verbindungen und Wechselwirkungen mit der Flüssigphase zu untersuchen, sind Modellstudien hilfreich.
Die Oxidation großer organischer Moleküle führt zu einer Vielzahl an Zwischenprodukten. Der Abbau erfolgt in unzähligen Reaktionen bis hin zum Endprodukt CO2. Bei der Entwicklung expliziter Mechanismen muss deshalb für diese Verbindungen auf computergestützte, automatisierte Methoden zurückgegriffen werden. Abschätzungsmethoden für die Vorhersage kinetischer Daten zur Beschreibung des Abbaus der Zwischenprodukte sind unabdingbar, da eine experimentelle Bestimmung aller benötigten Daten nicht realisierbar ist. Die derzeitige Beschreibung der Flüssigphasenchemie unterliegt deutlich den Beschreibungen der Gasphase in atmosphärischen Chemiemechanismen trotz deren Relevanz für die Multiphasenchemie.
In dieser Arbeit wurde der Gasphasenmechanismusgenerator GECKO-A (“Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere”) um ein Protokoll zur Oxidation organischer Verbindungen in der Flüssigphase erweitert. Dazu wurde eine Datenbank mit kinetischen Daten von 465 Hydroxylradikal- und 129 Nitratradikalreaktionen mit organischen Verbindungen angelegt und evaluiert. Mit Hilfe der Datenbank wurden derzeitige Abschätzungsmethoden für die Vorhersage kinetischer Daten von Flüssigphasenreaktionen organischer Verbindungen evaluiert. Die untersuchten Methoden beinhalteten Korrelationen kinetischer Daten aus Gas- und Flüssigphase, homologer Reihen verschiedener Stoffklassen, Reaktivitätsvergleiche, Evans-Polanyi-Korrelationen und Struktur-Reaktivitätsbeziehungen. Für die Mechanismusgenerierung großer organischer Moleküle wurden die Evans-Polanyi-Korrelationen in dieser Arbeit weiterentwickelt. Es wurde ein Protokol für die Mechanismusgenerierung entwickelt, das auf Struktur-Reaktivitätsbeziehungen bei Reaktionen von organischen Verbindungen mit OH-Radikalen und auf den erweiterten Evans-Polanyi-Korrelationen bei NO3-Radikalreaktionen beruht. Das Protokoll wurde umfangreich in einer Reihe von Sensitivitätsstudien getestet, um Unsicherheiten kritischer Parameter abzuschätzen.
Der erweiterte Multiphasengenerator GECKO-A wurde dazu verwendet, neue Mechanismen zu generieren, die in Boxmodellstudien gegen Aerosolkammerexperimente evaluiert wurden. Die Experimentreihen unterschieden sich sowohl in der betrachteten Ausgangssubstanz (Hexan und Trimethylbenzen) und dem Experimentaufbau (ohne oder mit UV-C-Photolyse und ohne oder mit zusätzlicher partikulärer Hydroxylradikalquelle). Bei den Experimenten konnte eine zufriedenstellende bis gute Übereinstimmung der experimentellen und Modellergebnisse erreicht werden.
Weiterhin wurde GECKO-A verwendet, um zwei neue CAPRAM-Versionen mit bis zu 4174 Verbindungen und 7145 Prozessen zu generieren. Erstmals wurden Verzweigungsverhältnisse in CAPRAM eingeführt. Außerdem wurde die Chemie organischer Verbindungen mit bis zu vier Kohlenstoffatomen erweitert. Umfangreiche Untersuchungen unter realistischen troposphärischen Bedingungen in urbanen und ländlichen Gebieten haben deutliche Verbesserungen der erweiterten Mechanismen besonders in Bezug auf Massenzuwachs des organischen Aerosolanteils gezeigt. Das Verständnis der organischen Multiphasenchemie konnte durch detaillierte Untersuchungen zu den Konzentrations-Zeit-Profilen und chemischen Flüssen vertieft werden, aber auch gegenwärtige Limitierungen des Generators, der erzeugten Mechanismen und unseres Verständnisses für Flüssigphasenprozesse organischer Verbindungen aufgezeigt werden.
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Extension and application of a tropospheric aqueous phase chemical mechanism (CAPRAM) for aerosol and cloud modelsBräuer, Peter 27 August 2015 (has links)
The ubiquitous abundance of organic compounds in natural and anthorpogenically influenced eco-systems has put these compounds into the focus of atmospheric research. Organic compounds have an impact on air quality, climate, and human health. Moreover, they affect particle growth, secondary organic aerosol (SOA) formation, and the global radiation budget by altering particle properties. To investigate the multiphase chemistry of organic compounds and interactions with the aqueous phase in the troposphere, modelling can provide a useful tool.
The oxidation of larger organic molecules to the final product CO2 can involve a huge number of intermediate compounds and tens of thousands of reactions. Therefore, the creation of explicit mechanisms relies on automated mechanism construction. Estimation methods for the prediction of the kinetic data needed to describe the degradation of these intermediates are inevitable due to the infeasibility of an experimental determination of all necessary data. Current aqueous phase descriptions of organic chemistry lag behind the gas phase descriptions in atmospheric chemical mechanisms despite its importance for the multiphase chemistry of organic compounds.
In this dissertation, the gas phase mechanism Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) has been advanced by a protocol for the description of the oxidation of organic compounds in the aqueous phase. Therefore, a database with kinetic data of 465 aqueous phase hydroxyl radical and 129 aqueous phase nitrate radical reactions with organic compounds has been compiled and evaluated. The database was used to evaluate currently available estimation methods for the prediction of aqueous phase kinetic data of reactions of organic compounds. Among the investigated methods were correlations of gas and aqueous kinetic data, kinetic data of homologous series of various compound classes, reactivity comparisons of inorganic radical oxidants, Evans-Polanyi-type correlations, and structure-activity relationships (SARs). Evans-Polanyi-type correlations have been improved for the purpose of automated mechanism self-generation of mechanisms with large organic molecules. A protocol has been designed based on SARs for hydroxyl radical reactions and the improved Evans-Polanyi-type correlations for nitrate radical reactions with organic compounds. The protocol was assessed in a series of critical sensitivity studies, where uncertainties of critical parameters were investigated.
The advanced multiphase generator GECKO-A was used to generate mechanisms, which were applied in box model studies and validated against two sets of aerosol chamber experiments. Experiments differed by the initial compounds used (hexane and trimethylbenzene) and the experimental conditions (UV-C lights off/on and additional in-situ hydroxyl radical source no/yes). Reasonable to good agreement of the modelled and experimental results was achieved in these studies.
Finally, GECKO-A was used to create two new CAPRAM version, where, for the first time, branchingratios for different reaction pathways were introduced and the chemistry of compounds with up to four carbon atoms has been extended. The most detailed mechanism comprises 4174 compounds and 7145 processes. Detailed investigations were performed under real tropospheric conditions in urban and remote continental environments. Model results showed significant improvements, especially in regard to the formation of organic aerosol mass. Detailed investigations of concentration-time profiles and chemical fluxes refined the current knowledge of the multiphase processing of organic compounds in the troposphere, but also pointed at current limitations of the generator protocol, the mechanisms created, and current understanding of aqueous phase processes of organic compounds.:1 Introduction and motivation
2 Theoretical background
2.1 General overview of the tropospheric multiphase chemistry of organic compounds
2.1.1 Gas phase chemistry
2.1.2 Phase transfer
2.1.3 Aqueous phase chemistry
2.2 Tropospheric multiphase chemistry mechanisms
2.2.1 Gas phase mechanisms
2.2.2 Aqueous phase mechanisms
2.2.3 The multiphase mechanism MCMv3.1-CAPRAM 3.0n
2.2.3.1 MCMv3.1
2.2.3.2 CAPRAM 3.0n
2.3 Multiphase chemistry box models
2.3.1 Overview
2.3.2 The model SPACCIM
2.3.2.1 Overview
2.3.2.2 The microphysical scheme
2.3.2.3 The chemical and phase transfer scheme
2.3.2.4 The coupling scheme
2.4 Prediction of aqueous phase kinetic data
2.4.1 Simple correlations
2.4.2 Evans-Polanyi-correlations
2.4.3 Structure-activity relationships
2.5 The generator GECKO-A
3 Evaluation of kinetic data and prediction methods
3.1 Compilation and evaluation of aqueous phase kinetic data
3.2 Extrapolation of gas phase rate constants to the aqueous phase
3.3 Homologous series of compound classes
3.4 Radical reactivity comparisons
3.5 Evans-Polanyi-type correlations
3.5.1 OH rate constant prediction
3.5.2 NO3 rate constant prediction
3.5.3 Development of an advanced Evans-Polanyi-type correlation
3.6 Structure-activity relationships
3.7 Conclusions from the evaluation process
4 Development of the new aqueous phase protocol and its implementation
into GECKO-A
4.1 Initialisation and workflow of GECKO-A
4.2 Estimation of phase transfer data
4.3 OH reactions of stable compounds
4.4 NO3 reactions of stable compounds
4.5 Hydration of carbonyl compounds
4.6 Hydrolysis of carbonyl nitrates
4.7 Dissociation of carboxylic acids
4.8 Degradation of radical compounds
4.8.1 RO2 recombinations and cross-reactions
4.8.2 HO2 elimination of ff-hydroxy peroxy radicals
4.8.3 Degradation of acylperoxy radicals
4.8.4 Degradation of fi-carboxyl peroxy radicals
4.8.5 Degradation of alkoxy radicals
4.8.6 Degradation of acyloxy radicals
5 Investigation and refinement of crucial parameters in GECKO-A and CAPRAM mechanism development
5.1 Formation and degradation of polycarbonyl compounds in the protocol
5.2 Influence of the mass accommodation coefficient on the organic multiphase chemistry and composition
5.3 Influence of the cut-off parameter for minor reaction pathways
5.4 Influence of the chosen SAR in the protocol
5.5 Processing of organic mass fraction in the protocol
5.5.1 Parameterisations for radical attack of the overall organic mass fraction
5.5.2 Detailed studies of organic nitrate sinks and sources
5.5.3 Phase transfer of oxygenated organic compounds in the protocol
5.5.4 Decay of alkoxy radicals in the protocol
5.5.5 Revision of the GROMHE thermodynamic database
5.6 Influence of the nitrate radical chemistry
5.7 The final protocol for aqueous phase mechanism self-generation
5.8 CAPRAM mechanism development
5.8.1 CAPRAM 3.0
5.8.2 CAPRAM 3.5
5.8.3 CAPRAM 4.0
6 Model results and discussion
6.1 Comparisons of model results with aerosol chamber experiments
6.1.1 Design of the aerosol chamber experiments
6.1.1.1 Hexane oxidation experiment
6.1.1.2 Trimethylbenzene oxidation experiment
6.1.2 Mechanism generation and model setup
6.1.2.1 Hexane oxidation experiment
6.1.2.2 Trimethylbenzene oxidation experiment
6.1.3 Evaluation of the model versus aerosol chamber results
6.1.3.1 Hexane oxidation experiment
6.1.3.2 Trimethylbenzene oxidation experiment
6.2 Simulations with a ‘real atmosphere’ scenario
6.2.1 Model setup
6.2.2 Meteorological and microphysical parameters
6.2.3 Influence of the extended organic scheme on the particle acidity and SOA formation
6.2.3.1 Particle acidity
6.2.3.2 Particle mass
6.2.4 Influence of the extended organic scheme on inorganic radical oxidants
6.2.4.1 OH chemistry
6.2.4.2 NO3 chemistry
6.2.4.3 Comparison of OH and NO3 chemistry
6.2.4.4 HO2/O2- chemistry
6.2.5 Influence of the extended organic scheme on inorganic non-radical oxidants
6.2.5.1 H2O2 chemistry
6.2.5.2 O3 chemistry
6.2.6 Influence of the extended organic scheme on inorganic particulate matter
6.2.6.1 Sulfate chemistry
6.2.6.2 Nitrate chemistry
6.2.6.3 TMI chemistry
6.2.7 Detailed investigations of selected organic subsystems
6.2.7.1 Monofunctional organic compounds
6.2.7.2 Carbonyl compounds
6.2.7.3 Dicarboxylic acids and functionalised monocarboxylic acids
7 Conclusions
References
Glossary
Acronyms
List of symbols
List of Figures
List of Tables
Acknowledgements
Curriculum Vitae
List of relevant publications
Peer-reviewed publications
Oral conference contributions
Poster conference contributions
Appendix
A Overview of selected compound classes of tropospheric relevance
B Detailed description of the function of SARs
C The kinetic database
C.1 Reactions of hydroxyl radicals with organic compounds
C.2 Reactions of nitrate radicals with organic compounds
D Detailed information about the evaluation of prediction methods
D.1 Rate data used for the derivation and evaluation of gas-aqueous phase
correlations
D.2 Explanation of the use of box plots
D.3 Additional correlations of homologous series of various compound classes
D.4 Additional information of Evans-Polanyi-type correlations
D.5 Additional information of structure-activity relationships
E Additional information for the development of the protocol of GECKO-A
E.1 Investigations on the decay of acylperoxy radicals
E.2 Additional information about the sensitivity of mass accomodation coefficients
E.3 Additional information about the sensitivity studies concerning the decay of polycarbonyls
E.4 Additional information about the sensitivity studies concerning the omission of minor reaction pathways
E.5 Additional information about the sensitivity studies concerning the processing of the organic mass fraction
E.6 Additional information about the influence of the nitrate radical chemistry
F Additional information about the mechanism generation and model initialisation
F.1 List of primary compounds used for the generation of CAPRAM 3.5
F.2 List of primary compounds used for the generation of CAPRAM 4.0
F.3 Model initialization of the ‘real atmosphere’ scenarios
G The CAPRAM oxidation scheme
G.1 Photolysis processes
G.2 Inorganic chemistry
G.2.1 Phase transfer processes
G.2.2 Chemical conversions
G.3 Organic chemistry
G.3.1 Phase transfer processes
G.3.2 Chemical conversions
H Detailed information about the model validation with chamber experiments
H.1 Additional information about the initialisation of the hexane oxidation
experiment
H.2 Additional model results from the hexane oxidation experiment
H.3 Additional information about the sensitivity runs used in the trimethylbenzene oxidation experiment
H.4 Additional results from the TMB oxidation experiment
I Additional results from the ‘real atmosphere’ scenario
I.1 Particle acidity and SOA formation
I.2 Radical oxidants
I.3 Organic compounds
References of the Appendix / Das zahlreiche Vorkommen organischer Verbindungen in natürlichen und anthropogen beeinflussten Ökosystemen hat diese Verbindungen in den Fokus der Atmosphärenforschung gerückt. Organische Verbindungen beeinträchtigen die Luftqualität, die menschliche Gesundheit und das Klima. Weiterhin werden Partikelwachstum und -eigenschaften, sekundäre organische Partikelbildung und dadurch der globale Strahlungshaushalt durch sie beeinflusst. Um die troposphärische Multiphasenchemie organischer Verbindungen und Wechselwirkungen mit der Flüssigphase zu untersuchen, sind Modellstudien hilfreich.
Die Oxidation großer organischer Moleküle führt zu einer Vielzahl an Zwischenprodukten. Der Abbau erfolgt in unzähligen Reaktionen bis hin zum Endprodukt CO2. Bei der Entwicklung expliziter Mechanismen muss deshalb für diese Verbindungen auf computergestützte, automatisierte Methoden zurückgegriffen werden. Abschätzungsmethoden für die Vorhersage kinetischer Daten zur Beschreibung des Abbaus der Zwischenprodukte sind unabdingbar, da eine experimentelle Bestimmung aller benötigten Daten nicht realisierbar ist. Die derzeitige Beschreibung der Flüssigphasenchemie unterliegt deutlich den Beschreibungen der Gasphase in atmosphärischen Chemiemechanismen trotz deren Relevanz für die Multiphasenchemie.
In dieser Arbeit wurde der Gasphasenmechanismusgenerator GECKO-A (“Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere”) um ein Protokoll zur Oxidation organischer Verbindungen in der Flüssigphase erweitert. Dazu wurde eine Datenbank mit kinetischen Daten von 465 Hydroxylradikal- und 129 Nitratradikalreaktionen mit organischen Verbindungen angelegt und evaluiert. Mit Hilfe der Datenbank wurden derzeitige Abschätzungsmethoden für die Vorhersage kinetischer Daten von Flüssigphasenreaktionen organischer Verbindungen evaluiert. Die untersuchten Methoden beinhalteten Korrelationen kinetischer Daten aus Gas- und Flüssigphase, homologer Reihen verschiedener Stoffklassen, Reaktivitätsvergleiche, Evans-Polanyi-Korrelationen und Struktur-Reaktivitätsbeziehungen. Für die Mechanismusgenerierung großer organischer Moleküle wurden die Evans-Polanyi-Korrelationen in dieser Arbeit weiterentwickelt. Es wurde ein Protokol für die Mechanismusgenerierung entwickelt, das auf Struktur-Reaktivitätsbeziehungen bei Reaktionen von organischen Verbindungen mit OH-Radikalen und auf den erweiterten Evans-Polanyi-Korrelationen bei NO3-Radikalreaktionen beruht. Das Protokoll wurde umfangreich in einer Reihe von Sensitivitätsstudien getestet, um Unsicherheiten kritischer Parameter abzuschätzen.
Der erweiterte Multiphasengenerator GECKO-A wurde dazu verwendet, neue Mechanismen zu generieren, die in Boxmodellstudien gegen Aerosolkammerexperimente evaluiert wurden. Die Experimentreihen unterschieden sich sowohl in der betrachteten Ausgangssubstanz (Hexan und Trimethylbenzen) und dem Experimentaufbau (ohne oder mit UV-C-Photolyse und ohne oder mit zusätzlicher partikulärer Hydroxylradikalquelle). Bei den Experimenten konnte eine zufriedenstellende bis gute Übereinstimmung der experimentellen und Modellergebnisse erreicht werden.
Weiterhin wurde GECKO-A verwendet, um zwei neue CAPRAM-Versionen mit bis zu 4174 Verbindungen und 7145 Prozessen zu generieren. Erstmals wurden Verzweigungsverhältnisse in CAPRAM eingeführt. Außerdem wurde die Chemie organischer Verbindungen mit bis zu vier Kohlenstoffatomen erweitert. Umfangreiche Untersuchungen unter realistischen troposphärischen Bedingungen in urbanen und ländlichen Gebieten haben deutliche Verbesserungen der erweiterten Mechanismen besonders in Bezug auf Massenzuwachs des organischen Aerosolanteils gezeigt. Das Verständnis der organischen Multiphasenchemie konnte durch detaillierte Untersuchungen zu den Konzentrations-Zeit-Profilen und chemischen Flüssen vertieft werden, aber auch gegenwärtige Limitierungen des Generators, der erzeugten Mechanismen und unseres Verständnisses für Flüssigphasenprozesse organischer Verbindungen aufgezeigt werden.:1 Introduction and motivation
2 Theoretical background
2.1 General overview of the tropospheric multiphase chemistry of organic compounds
2.1.1 Gas phase chemistry
2.1.2 Phase transfer
2.1.3 Aqueous phase chemistry
2.2 Tropospheric multiphase chemistry mechanisms
2.2.1 Gas phase mechanisms
2.2.2 Aqueous phase mechanisms
2.2.3 The multiphase mechanism MCMv3.1-CAPRAM 3.0n
2.2.3.1 MCMv3.1
2.2.3.2 CAPRAM 3.0n
2.3 Multiphase chemistry box models
2.3.1 Overview
2.3.2 The model SPACCIM
2.3.2.1 Overview
2.3.2.2 The microphysical scheme
2.3.2.3 The chemical and phase transfer scheme
2.3.2.4 The coupling scheme
2.4 Prediction of aqueous phase kinetic data
2.4.1 Simple correlations
2.4.2 Evans-Polanyi-correlations
2.4.3 Structure-activity relationships
2.5 The generator GECKO-A
3 Evaluation of kinetic data and prediction methods
3.1 Compilation and evaluation of aqueous phase kinetic data
3.2 Extrapolation of gas phase rate constants to the aqueous phase
3.3 Homologous series of compound classes
3.4 Radical reactivity comparisons
3.5 Evans-Polanyi-type correlations
3.5.1 OH rate constant prediction
3.5.2 NO3 rate constant prediction
3.5.3 Development of an advanced Evans-Polanyi-type correlation
3.6 Structure-activity relationships
3.7 Conclusions from the evaluation process
4 Development of the new aqueous phase protocol and its implementation
into GECKO-A
4.1 Initialisation and workflow of GECKO-A
4.2 Estimation of phase transfer data
4.3 OH reactions of stable compounds
4.4 NO3 reactions of stable compounds
4.5 Hydration of carbonyl compounds
4.6 Hydrolysis of carbonyl nitrates
4.7 Dissociation of carboxylic acids
4.8 Degradation of radical compounds
4.8.1 RO2 recombinations and cross-reactions
4.8.2 HO2 elimination of ff-hydroxy peroxy radicals
4.8.3 Degradation of acylperoxy radicals
4.8.4 Degradation of fi-carboxyl peroxy radicals
4.8.5 Degradation of alkoxy radicals
4.8.6 Degradation of acyloxy radicals
5 Investigation and refinement of crucial parameters in GECKO-A and CAPRAM mechanism development
5.1 Formation and degradation of polycarbonyl compounds in the protocol
5.2 Influence of the mass accommodation coefficient on the organic multiphase chemistry and composition
5.3 Influence of the cut-off parameter for minor reaction pathways
5.4 Influence of the chosen SAR in the protocol
5.5 Processing of organic mass fraction in the protocol
5.5.1 Parameterisations for radical attack of the overall organic mass fraction
5.5.2 Detailed studies of organic nitrate sinks and sources
5.5.3 Phase transfer of oxygenated organic compounds in the protocol
5.5.4 Decay of alkoxy radicals in the protocol
5.5.5 Revision of the GROMHE thermodynamic database
5.6 Influence of the nitrate radical chemistry
5.7 The final protocol for aqueous phase mechanism self-generation
5.8 CAPRAM mechanism development
5.8.1 CAPRAM 3.0
5.8.2 CAPRAM 3.5
5.8.3 CAPRAM 4.0
6 Model results and discussion
6.1 Comparisons of model results with aerosol chamber experiments
6.1.1 Design of the aerosol chamber experiments
6.1.1.1 Hexane oxidation experiment
6.1.1.2 Trimethylbenzene oxidation experiment
6.1.2 Mechanism generation and model setup
6.1.2.1 Hexane oxidation experiment
6.1.2.2 Trimethylbenzene oxidation experiment
6.1.3 Evaluation of the model versus aerosol chamber results
6.1.3.1 Hexane oxidation experiment
6.1.3.2 Trimethylbenzene oxidation experiment
6.2 Simulations with a ‘real atmosphere’ scenario
6.2.1 Model setup
6.2.2 Meteorological and microphysical parameters
6.2.3 Influence of the extended organic scheme on the particle acidity and SOA formation
6.2.3.1 Particle acidity
6.2.3.2 Particle mass
6.2.4 Influence of the extended organic scheme on inorganic radical oxidants
6.2.4.1 OH chemistry
6.2.4.2 NO3 chemistry
6.2.4.3 Comparison of OH and NO3 chemistry
6.2.4.4 HO2/O2- chemistry
6.2.5 Influence of the extended organic scheme on inorganic non-radical oxidants
6.2.5.1 H2O2 chemistry
6.2.5.2 O3 chemistry
6.2.6 Influence of the extended organic scheme on inorganic particulate matter
6.2.6.1 Sulfate chemistry
6.2.6.2 Nitrate chemistry
6.2.6.3 TMI chemistry
6.2.7 Detailed investigations of selected organic subsystems
6.2.7.1 Monofunctional organic compounds
6.2.7.2 Carbonyl compounds
6.2.7.3 Dicarboxylic acids and functionalised monocarboxylic acids
7 Conclusions
References
Glossary
Acronyms
List of symbols
List of Figures
List of Tables
Acknowledgements
Curriculum Vitae
List of relevant publications
Peer-reviewed publications
Oral conference contributions
Poster conference contributions
Appendix
A Overview of selected compound classes of tropospheric relevance
B Detailed description of the function of SARs
C The kinetic database
C.1 Reactions of hydroxyl radicals with organic compounds
C.2 Reactions of nitrate radicals with organic compounds
D Detailed information about the evaluation of prediction methods
D.1 Rate data used for the derivation and evaluation of gas-aqueous phase
correlations
D.2 Explanation of the use of box plots
D.3 Additional correlations of homologous series of various compound classes
D.4 Additional information of Evans-Polanyi-type correlations
D.5 Additional information of structure-activity relationships
E Additional information for the development of the protocol of GECKO-A
E.1 Investigations on the decay of acylperoxy radicals
E.2 Additional information about the sensitivity of mass accomodation coefficients
E.3 Additional information about the sensitivity studies concerning the decay of polycarbonyls
E.4 Additional information about the sensitivity studies concerning the omission of minor reaction pathways
E.5 Additional information about the sensitivity studies concerning the processing of the organic mass fraction
E.6 Additional information about the influence of the nitrate radical chemistry
F Additional information about the mechanism generation and model initialisation
F.1 List of primary compounds used for the generation of CAPRAM 3.5
F.2 List of primary compounds used for the generation of CAPRAM 4.0
F.3 Model initialization of the ‘real atmosphere’ scenarios
G The CAPRAM oxidation scheme
G.1 Photolysis processes
G.2 Inorganic chemistry
G.2.1 Phase transfer processes
G.2.2 Chemical conversions
G.3 Organic chemistry
G.3.1 Phase transfer processes
G.3.2 Chemical conversions
H Detailed information about the model validation with chamber experiments
H.1 Additional information about the initialisation of the hexane oxidation
experiment
H.2 Additional model results from the hexane oxidation experiment
H.3 Additional information about the sensitivity runs used in the trimethylbenzene oxidation experiment
H.4 Additional results from the TMB oxidation experiment
I Additional results from the ‘real atmosphere’ scenario
I.1 Particle acidity and SOA formation
I.2 Radical oxidants
I.3 Organic compounds
References of the Appendix
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Unusual Sesquiterpenes: Gorgonenes and Further Bioactive Secondary Metabolites Derived from Marine and Terrestrial Bacteria. / Ungewöhnliche Sequiterpene: Gorgonene und weitere bioaktive Sekundärstoffe aus marinen und terrestrischen Bakterien.Rahman, Hafizur 29 October 2008 (has links)
No description available.
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Three step modelling approach for the simulation of industrial scale pervaporation modulesSchiffmann, Patrick 21 August 2014 (has links) (PDF)
The separation of aqueous and organic mixtures with thermal separation processes is an important and challenging task in the chemical industry. Rising prices for energy, stricter environmental regulations and the increasing demand for high purity chemicals are the main driving forces to find alternative solutions to common separation technologies such as distillation and absorption. These are mostly too energy consumptive and can show limited separation performance, especially when applied to close boiling or azeotropic mixtures. Pervaporation can overcome these thermodynamic limitations and requires less energy because only the separated components need to be evaporated. This separation technology is already well established for the production of anhydrous solvents, but not yet widely distributed in the chemical and petrochemical industry due to some crucial challenges, which are still to overcome.
Besides the need of high selective membranes, the development of membrane modules adapted to the specific requirements of organoselective pervaporation needs more research effort. Furthermore, only few modelling and simulation tools are available, which hinders the distribution of this process in industrial scale.
In this work, these issues are addressed in a combined approach. In close collaboration with our cooperation partners, a novel membrane module for organophilic pervaporation is developed. A novel technology to manufacture high selective polymeric pervaporation membranes is applied to produce a membrane for an industrially relevant organic-organic separation task. A three step modelling approach ranging from a shortcut and a discrete to a rigorous model is developed and implemented in a user interface. A hydrophilic and an organophilic membrane are characterised for the separation of a 2-butanol/water mixture in a wide range of feed temperature and feed concentration in order to establish a generally valid description of the membrane performances. This approach is implemented in the three developed models to simulate the novel membrane module in industrial scale. The simulations are compared to the results of pilot scale experiments conducted with the novel membrane module. Good agreement between simulated and experimental values is reached.
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Untersuchungen zum Transfer von anorganischen und organischen Schadstoffen aus dotiertem Substrat in Gemüsepflanzen (Tomaten, Paprika)Friedrich, Nadine 30 August 2011 (has links) (PDF)
In der vorliegenden Arbeit wurde mit Hilfe von Gefäßversuchen der Transfer von ausgewählten organischen (m-Kresol, Simazin, Lindan, Anthracen, Galaxolid) und anorganischen Umweltschadstoffen (As, Cd, Pb, Cr, Zn, Ni) aus dotiertem Substrat in Nutzpflanzen (Tomaten, Paprika) untersucht. Zum besseren Verständnis des Schadstofftransfers der organischen Verbindungen und als Möglichkeit einer kosten- und zeitsparenden Alternative zu den herkömmlichen Untersuchungsverfahren, wurden ergänzend in vivo – Experimente durchgeführt. Weitere Schwerpunkte der Arbeit waren Untersuchungen zur Schadstoffaufnahme durch Pflanzen in Abhängigkeit von der Substratkonzentration sowie der Vegetationsdauer. Ein weiterer Schwerpunkt der Arbeiten waren Studien über mögliche Einflüsse eines neuartigen Bodenverbesserungsmaterials auf die Schadstoffmobilität und Bioverfügbarkeit der oben genannten potentiellen Schadstoffe sowie die damit verbundene mögliche Aufnahme durch die Untersuchungspflanzen.
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Untersuchungen zum Transfer von anorganischen und organischen Schadstoffen aus dotiertem Substrat in Gemüsepflanzen (Tomaten, Paprika)Friedrich, Nadine 11 July 2011 (has links)
In der vorliegenden Arbeit wurde mit Hilfe von Gefäßversuchen der Transfer von ausgewählten organischen (m-Kresol, Simazin, Lindan, Anthracen, Galaxolid) und anorganischen Umweltschadstoffen (As, Cd, Pb, Cr, Zn, Ni) aus dotiertem Substrat in Nutzpflanzen (Tomaten, Paprika) untersucht. Zum besseren Verständnis des Schadstofftransfers der organischen Verbindungen und als Möglichkeit einer kosten- und zeitsparenden Alternative zu den herkömmlichen Untersuchungsverfahren, wurden ergänzend in vivo – Experimente durchgeführt. Weitere Schwerpunkte der Arbeit waren Untersuchungen zur Schadstoffaufnahme durch Pflanzen in Abhängigkeit von der Substratkonzentration sowie der Vegetationsdauer. Ein weiterer Schwerpunkt der Arbeiten waren Studien über mögliche Einflüsse eines neuartigen Bodenverbesserungsmaterials auf die Schadstoffmobilität und Bioverfügbarkeit der oben genannten potentiellen Schadstoffe sowie die damit verbundene mögliche Aufnahme durch die Untersuchungspflanzen.
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