Rice grows in saturated soil water condition and its requirement for water is highest amongst other cereal crops. In India, the southwest monsoon wind regime brings rainfall that provides a favourable environment for rice cultivation. Thus, there is significant dependency ofrice production on the southwest monsoon rainfall. Being a crop that grows across diverse climatic regions in India ranging from the humid to semi-arid, it offers possibility to explore therelationship between stable isotopic compositions in the grain organic matter with the climaticfactors relevant for its growth. In this thesis, we measured the isotopic compositions of oxygen, hydrogen and carbon of several rice genotypes that were cultivated during the southwest monsoon in diverse climatic regions across the Indian landmass. These isotopic values were then compared with the seasonalaverage values of climate factors such as relative humidity and temperature. Together with thiswe also studied the dependency of the oxygen isotope composition of the grain OM (δ18OOM) onthat of the source water (δ18OSW). Upon removal of δ18OSW effect from δ18OOM, we obtained astrong and significant relationship between the 18O enrichment in grain organic matter (definedas 18OOM) with relative humidity. The gradient recorded was 0.45‰ shift in 18OOM with 1%change in the relative humidity level. This relationship can potentially be used to estimate thepast variations in relative humidity (and by extension, can provide a measure of monsoon rainfallvariations). We further validated this relationship based on experiments carried out in aglasshouse where all the physical factors were well-monitored. Together with this, carbonisotopic composition measured in the rice grain organic matter were used to infer the water useefficiency of rice grown in different climatic settings. The stable isotope approach was furtherimplemented for studying the archaeological rice grains recovered from archaeological sites. Analysis of carbon isotopic composition of archaeological rice grains from seven archaeologicalsites (Balu, Kanmer, Ojiyana, Lahuradewa, JognaKhera, Hulas and Kunal), belonging to theHarappan civilization and other contemporary cultures provided a new suit of data on quantitativeestimate of the hydroclimatic condition (specifically relative humidity) and water availabilityduring the existence of this civilization

Rice grows in saturated soil water condition and its requirement for water is highest amongst other cereal crops. In India, the southwest monsoon wind regime brings rainfall that provides a favourable environment for rice cultivation. Thus, there is significant dependency ofrice production on the southwest monsoon rainfall. Being a crop that grows across diverse climatic regions in India ranging from the humid to semi-arid, it offers possibility to explore therelationship between stable isotopic compositions in the grain organic matter with the climaticfactors relevant for its growth. In this thesis, we measured the isotopic compositions of oxygen, hydrogen and carbon of several rice genotypes that were cultivated during the southwest monsoon in diverse climatic regions across the Indian landmass. These isotopic values were then compared with the seasonalaverage values of climate factors such as relative humidity and temperature. Together with thiswe also studied the dependency of the oxygen isotope composition of the grain OM (δ18OOM) onthat of the source water (δ18OSW). Upon removal of δ18OSW effect from δ18OOM, we obtained astrong and significant relationship between the 18O enrichment in grain organic matter (definedas 18OOM) with relative humidity. The gradient recorded was 0.45‰ shift in 18OOM with 1%change in the relative humidity level. This relationship can potentially be used to estimate thepast variations in relative humidity (and by extension, can provide a measure of monsoon rainfallvariations). We further validated this relationship based on experiments carried out in aglasshouse where all the physical factors were well-monitored. Together with this, carbonisotopic composition measured in the rice grain organic matter were used to infer the water useefficiency of rice grown in different climatic settings. The stable isotope approach was furtherimplemented for studying the archaeological rice grains recovered from archaeological sites. Analysis of carbon isotopic composition of archaeological rice grains from seven archaeologicalsites (Balu, Kanmer, Ojiyana, Lahuradewa, JognaKhera, Hulas and Kunal), belonging to theHarappan civilization and other contemporary cultures provided a new suit of data on quantitativeestimate of the hydroclimatic condition (specifically relative humidity) and water availabilityduring the existence of this civilization.

[pt] A distribuição molecular e as composições isotópicas estáveis (d13C, dD) de n-alcanos e ácidos graxos saturados foram investigadas em um testemunho sedimentar marinho (GeoB16202-1, 773cm) coletado na bacia do rio Parnaíba para determinar as fontes da matéria orgânica terrestre depositada durante os últimos 23000 anos. As composições isotópicas de carbono dos n-alcanos e ácidos graxos foram consideradas para inferir mudanças na vegetação de acordo com a variabilidade climática, enquanto as composições de hidrogênio forneceram informações sobre eventos milenares na hidrologia regional e sua relação com as forçantes climáticas globais. Os n-alcanos de cadeia longa (n-Nonacosano C29 e n-Hentriacontano C31) e os ácidos graxos saturados C26 (ácido hexacosanoico) e (ácido montânico) C28 foram os compostos mais abundantes determinados, sugerindo contribuições importantes de material de origem terrestre. Os valores mais negativos de d13C para C29 e C31 (-27,3 a -33,2 % VPDB – Vienna Pee Dee Belemnite) indicam uma predominância geral de vegetação C3 ao longo do testemunho. A composição isotópica de carbono dos ácidos graxos de cadeia longa (d13C de -27,3 e -34,5 % VPDB) variou em uma faixa semelhante e exibiu uma distribuição altamente correlacionada com os alcanos de cadeia longa, o que sugere uma origem comum e confirma o uso do d13C de ácidos graxos como indicador de paleovegetação. O dD dos n-alcanos de cadeia longa (-115 a -159 % SMOW – Standard Mean Ocean Water) variou em uma faixa mais positiva do que a composição dos ácidos graxos (-123 e -163 % SMOW) e ambos os sinais apresentam correlação positiva. O d13C de n-alcanos de cadeia longa e ácidos graxos sugere a expansão de plantas C3 e o dD sugere maior precipitação durante os eventos Heinrich Stadial1 (HS1) e Younger Dryas (YD), o que é consistente com estudos prévios que atribuem um regime de chuvas mais intenso no Nordeste do Brasil durante esses períodos. A distribuição molecular e a composição isotópica (d13C e dD) do ácido palmítico C16 revelam que os ácidos graxos de cadeia curta são provenientes de uma combinação de material ressintetizado e / ou uma mistura de matéria orgânica marinha / terrestre, enquanto os ácidos graxos C26 e C28 originam-se de plantas terrestres. A menor correlação entre o dD dos ácidos graxos e dD dos n-alcanos sugere que a assinatura isotópica de hidrogênio de ambos os grupos de compostos é afetada por diferentes processos que precisam ser investigados mais profundamente. / [en] Molecular distribution and stable isotopic compositions (d13C, dD) of n-alkanes and saturated fatty acids were investigated in a marine sediment core (GeoB16202-1, 773cm) collected in Parnaíba river basin to determine the sources of terrestrial organic matter deposited during the last 23000 years. The carbon isotopic compositions of n-alkanes and fatty acids were considered to infer vegetation changes according with climatic variations, while the hydrogen compositions provided information about millenary events in regional hydrology and its relationship with the global climate forcings. Long-chain n-alkanes (n-Nonacosane C29 and n-Hentriacontane C31) and saturated fatty acids C26 (hexacosanoic acid) and C28 (montanic acid) were the most abundant compounds determined, suggesting important contributions from terrestrial sources. The most negative values of d13C for C29 and C31 (-27.3 to -33.2 % VPDB – Vienna Pee Dee Belemnite) indicate a general predominance of C3 vegetation along the core. The carbon isotopic composition of the long-chain fatty acids (d13C of -27.3 and -34.5 % VPDB) varied in a similar range and exhibited a distribution highly correlated with the long-chain n-alkanes, which suggests a common origin and confirms the use of d13C from fatty acids as a paleovegetation proxy. The dD of the long-chain n-alkanes (-115 to -159 % SMOW– Standard Mean Ocean Water) varied in a more positive range than the composition of the fatty acids (-123 and -163 % SMOW) and both signs were positively correlated. The d13C of long-chain n-alkanes and fatty acids suggests expansion of C3 plants and the dD suggests greater precipitation during the Heinrich Stadial1 (HS1) and Younger Dryas (YD) events, which is consistent with previous studies that attribute a regime of more intense rainfall in Northeast of Brazil during these periods. Molecular distribution and isotopic compositions (d13C and dD) of palmitic acid (C16 ) reveal that the short-chain fatty acids correspond a combination of resynthesized material and/or a mixture of marine/terrestrial organic matter, while terrestrial plants are the principal sources of the fatty acids C26 and C28. The lower correlation between dD of fatty acids and dD of n-alkanes suggests that the hydrogen isotope signature of both groups of compounds is affected by different processes that need to be further investigated.

"A Terminal Report Submitted 31 October, 1981 on the National Science Foundation grant EAR 78-04436 with the assistance of the Department of Energy contract no. EE-78-A-28-3274"

"A Final Technical Report Submitted 31 May 1985 on the National Science Foundation grant EAR-8018687 for the period 1 April 1981 to 31 October 1984 with the assistance of the Department of Energy contract no. DE-AC02-81EV10680 covering the period 1 May 1981 to 31 October 1982" / Since Edmund Schulman’s initial interest in 1953, the Laboratory of Tree-Ring Research has conducted dendrochronological studies of bristlecone pine (Pinus longaeva D. K. Bailey, sp. Nov.) in the White Mountains of east-central California where living trees reach ages in excess of 4,000 years. The focus of this report relates to the support by the Geology and Anthropology sections in the National Science Foundation under grant EAR-8018687 for the period 1 April 1981 to 31 October 1984 with the assistance of the Department of Energy contract no. DE-AC02-81EV10680 covering the period 1 May 1981 to 31 October 1982. A summary of this research was recently published in Radiocarbon (Ferguson and Graybill 1983). In most cases various facets of the work were related to projects sponsored by all agencies. Therefore the full range of activities during that period is described herein. The primary project goals were: To extend the bristlecone pine chronology from the White Mountains of California beyond 6700 B.C. and strengthen it by incorporating additional specimens. To develop bristlecone pine chronologies in new areas for applications in archaeology, isotopic studies, and other earth sciences. To furnish dendrochronologically dated wood to researchers engaged in the study of past variations in carbon isotopes and climate.

The rotational microwave spectra of the three isotopes (^13CH_3^12C^15N, ^12CH_3^13C^15N, and ^13CH_3^13C^15N) of the methyl cyanide molecule in the v_8=3, v_8=2, v_7=1 and v_4=1 vibrational energy levels for the rotational components 1£J£5 (for a range of frequency 17-95 GHz.) were experimentally and theoretically examined. Rotational components in each vibration were measured to determine the mutual interactions in each vibration between any of the vibrational levels investigated. The method of isotopic substitution was employed for internal tuning of each vibrational level by single and double substitution of ^13C in the two sites of the molecule. It was found that relative frequencies within each vibration with respect to another vibration were shifted in a systematic way. The results given in this work were interpreted on the basis of these energy shifts. Large departure between experimentally measured and theoretically predicted frequency for the quantum sets (J, K=±l, ϑ=±1), Kϑ-l in the v_8=3 vibrational states for the ^13c and ^15N tagged isotopes of CH_3CN showed anomalous behavior which was explained as being due to Fermi resonance. Accidently strong resonances (ASR) were introduced to account for some departures which were not explained by Fermi resonance.

This thesis combines solid-state nuclear magnetic resonance (NMR) spectroscopy, X-ray diffraction (XRD), chemical synthesis, isotopic enrichment and density-functional theory (DFT) calculations to provide insight into a number of microporous materials. The first class of materials studied is metal-organic frameworks (MOFs), where the presence of paramagnetic ions has a range of effects on the ¹³C NMR spectra, depending on the nature of the ligand-metal interactions. For the Cu²⁺-based MOFs, HKUST-1 and STAM-1, the assignment of the NMR spectra is non-intuitive, and unambiguous assignment requires specific ¹³C labelling of the organic linker species. It is shown that ¹³C NMR spectra of these two MOFs could act as a sensitive probe of the nature of “guest” molecules bound to the Cu²⁺. The second class of materials is aluminophosphates (AlPOs). It is shown that, using a series of relatively simple linear relationships with the crystal structure, the NMR parameters calculated by DFT (with calculation times of several hours) can be predicted, often with experimentally-useful accuracy, in a matter of seconds using the DIStortion analysis COde (DISCO), which is introduced here. The ambient hydration of the AlPO, JDF-2, to AlPO-53(A) is shown to occur slowly, with incomplete hydration after ~3 months. The resulting AlPO-53(A) is disordered and some possible models for this disorder are investigated by DFT. The final class of materials is gallophosphates (GaPOs), particularly GaPO-34 and related materials. The two as-prepared forms of GaPO-34 are characterised by solid-state NMR, and their calcination investigated by TGA and in-situ powder XRD. An unusual dehydrofluorinated intermediate phase is isolated and characterised for the first time by solid-state NMR. The fully calcined material is shown to be stable under anhydrous conditions, but hydrates rapidly in air. The hydrated material is stable under ambient conditions, but collapses upon heating. Partial dehydration without collapse is achieved by gentle heating or room-temperature evacuation. The impurity phases, GaPO₄ berlinite and GaPO-X are investigated by solid-state NMR and, while the structure of GaPO-X remains unknown, much structural information is obtained.

L'achèvement de la fermentation alcoolique est corrélé au niveau de formation de biomasse, qui varie selon les souches de levure S. cerevisiae. La maîtrise de cette fermentation passe par une meilleure compréhension des liens entre métabolisme azoté et formation de biomasse ainsi que des mécanismes contribuant aux variations de formation de biomasse entre souches. L'analyse des cinétiques de consommation de 18 composés azotés a montré que l'ordre de consommation des sources d'azote est similaire pour 14 souches et s'explique principalement par les caractéristiques cinétiques et le mode de régulation des perméases impliquées dans leur transport. Par contre, des variations sont observées dans les profils de consommation de l'azote, qui mettent en jeu des mécanismes différents suivant la disponibilité en azote du milieu. En présence d'un excès d'azote, les souches « faibles productrices » présentent une capacité limitée d'assimilation de l'ammonium ; lorsque l'azote est présent en faible quantité, elles métabolisent plus efficacement l'arginine stockée dans la vacuole pendant la phase de croissance. Afin de déterminer la distribution des flux d'azote dans la cellule, nous avons développé une approche quantitative basée sur la filiation isotopique de sources d'azote marquées 13C ou 15N. Cette étude a révélé une incorporation limitée des acides aminés exogènes dans la biomasse au profit de la synthèse de novo, à l'exception de la leucine majoritairement intégrée dans la biomasse et de l'arginine stockée dans la vacuole. Enfin, cette étude a confirmé expérimentalement que les capacités d'assimilation de l'ammonium et de remobilisation de l'arginine sont des éléments clés des différences de production de biomasse entre souches. Cette étude apporte un nouvel éclairage sur l'efficacité d'utilisation et l'allocation de sources complexes d'azote pendant la fermentation œnologique et sur les mécanismes impliqués dans la variabilité de production de biomasse chez S. cerevisiae. / The completion of alcoholic fermentation is correlated with the level of biomass formation, which varies depending on the S. cerevisiae yeast strain. Achieving a better control of the fermentation requires a better understanding of the relationship between nitrogen metabolism and biomass formation and of the mechanisms contributing to variation in biomass formation between strains. The analysis of the kinetics of consumption of 18 nitrogen compounds showed that the order of consumption of nitrogen sources is similar for 14 strains and is mainly due to the kinetic characteristics and mode of regulation of permeases involved in their transport. By cons, variations are observed in the patterns of nitrogen consumption, which involve different mechanisms depending on the availability of nitrogen in the medium. In the presence of excess nitrogen, "low producing" strains have a limited capacity for assimilation of ammonium; when nitrogen is present in small quantities, they metabolize more efficiently arginine stored in the vacuole during the growth phase. To determine the intracellular distribution of nitrogen fluxes, we developed a quantitative approach based on isotopic filiation of 13C or 15N labeled nitrogen sources. This study revealed a limited incorporation of exogenous amino acids in biomass in favor of de novo synthesis, with the exception of leucine mostly integrated in the biomass and arginine stored in the vacuole. Finally, this study confirmed experimentally that the capacity of ammonium assimilation and remobilization of arginine are key determinant governing the differences of biomass production between strains. This study sheds new light on the efficient use and allocation of complex nitrogen sources during wine fermentation and on the mechanisms involved in the differences in biomass production within the S. cerevisiae species.

Les travaux de cette thèse se sont situés autour de la relation entre discrimination isotopique du carbone 13 et échanges gazeux foliaires. Le modèle établi par Farquhar et al. (1982) permet de prédire la discrimination contre le 13C pendant la photosynthèse (delta13C) en tenant compte des processus de diffusion, de carboxylation et décarboxylation engagés pendant la photosynthèse. Cette relation permet d'utiliser delta13C comme indicateur de l'efficience d'utilisation de l'eau (WUE, quantité de carbone fixé en fonction de l'eau consommée), un paramètre particulièrement important dans un contexte de changement climatique, d'agriculture et de sylviculture. Le modèle de delta13C a également été utilisé pour estimer la conductance mésophyllienne au CO2 (gm), un paramètre qui limite fortement la photosynthèse via la disponibilité en carbone dans le chloroplaste. Au cours de nos travaux, nous avons analysé le modèle delta13C pour identifier les paramètres les plus influents dans le modèle, et mis en évidence que l'utilisation du "modèle simple" de delta13C (ignorant gm et les processus de décarboxylation) peut induire un biais important dans l'estimation de WUE. Dans un second temps nous nous sommes concentrés sur les possibles variations à court-terme de gm, un domaine encore sujet a débat. Nous avons confirmé que gm était sensible aux variations de CO2 et d'irradiance sur toutes les espèces d'arbres mesurées dans cette étude. Nous avons aussi montré que ces variations rapides ne peuvent pas être dues a des variations des autres paramètres du modèle, à l'exception possible du paramètre b (discrimination pendant la carboxylation). Nous suggérons que les prochaines études dans ce domaine portent sur (i) la possible variabilité environnementale et génétique du paramètre b et (ii) les mécanismes à l'origine des variations rapides de gm (aquaporines et anhydrases carboniques) / This work was focused on the relationship between isotopic discrimination of 13C during photosynthesis (delta13C) and leaf gas exchange. The model of Farquhar and colleagues (Farquhar et al. 1982) predicts delta13C by accounting for diffusion, carboxylation and decarboxylation processes during the photosynthesis. This relationship is widely used and delta13C is frequently considered as a proxy water use efficiency (WUE, the amount of water required to fix a amount of carbon), an interesting parameter in the context of climate change, crop production and sylviculture. The delta13C model is also used to assess mesophyll conductance to CO2 (gm), that strongly limits photosynthesis via the availability of carbon in the chloroplast. Along this work we analyzed the delta13C model and identified the most important parameters, and highlighted that using the "simple form" of the model (which ignores gm and the decarboxylations) could lead to misestimating WUE. We also focused on the possible rapid variations of gm, a subject still under debate. We confirmed that gm was sensitive to rapid variations of CO2 and irradiance in all species tested in this study. We also showed that apparent rapid variations of gm could not be induced by variations of other parameters in the model, with the exception of parameter b (discrimination during carboxylation). We propose that future studies should focus on (i) the possible environmental and genetic variability of parameter b, and (ii) the physiological processes able to change gm at short time scales (aquaporins and carbonic anhydrase).

La réaction de formation de l’ozone O+O2+M→O3+M est un exemple unique de réaction chimique qui mène à une composition isotopique anormale des produits, probablement due à une brisure de symétrie. L’existence d’autres réactions chimiques présentant des effets isotopiques similaires est encore controversée malgré des études affirmant que de telles réactions existent. Ainsi, deux études sur la réaction O+CO+M → CO2+M indiquent un fractionnement indépendant de la masse de 8% environ. Néanmoins, la présence d’ozone dans ces expériences soulève des questions en ce qui concerne la validité des résultats. Nous avons donc étudié à nouveau la réaction O+CO+M dans le photoréacteur installé au CCAR (Université de Copenhague) où les réactifs et les contaminants sont surveillés par spectroscopie FTIR. Cette étude, combinée avec l’analyse de la distribution spectrale des lampes utilisées et la modélisation cinétique des isotopes, mène à une réinterprétation complète des expériences précédentes. Nous concluons que les mesures disponibles sont plus compatibles avec l’hypothèse qu’aucune anomalie isotopique indépendante de la masse n’a lieu dans la réaction O+CO et que toutes les observations peuvent être complètement expliquées par un transfert isotopique à partir de l’ozone.Nous présentons également une méthode pour produire des échantillons d’ozone à haute pureté et déterminer une limite supérieure des contaminations par les oxydes d’azote basée sur des mesures par spectrométrie de masse. Ces valeurs pourront être utilisées comme référence pour de futures études sur les sections efficaces d’absorption de l’ozone dans l’IR et l’UV. / The ozone formation reaction O+O2+M→O3+M is a unique example of a chemical reaction that leads to an anomalous isotopic composition of the products, most likely due to symmetry – breaking effects. So far, results on other chemical systems that might show similar effects are spurious, even though such claims concerning reactions other than the formation of ozone have been made repeatedly.This applies in particular to the spin forbidden O+CO+M→CO2+M reaction, where two studies report a mass-independent fractionation of about 8%. Nevertheless, the presence of ozone in these experiments raises questions as to the validity of this assertion. We thus make a new attempt to study the O+CO+M reaction in the photoreactor at CCAR (University of Copenhagen) where reagents and contaminants are monitored on-line by FTIR spectroscopy. This study combined with the analysis of the spectral distribution of the employed lamps and isotope kinetic modeling lead to a complete re-interpretation of previous experiments. We conclude that available measurements are more compatible with the hypothesis that there is no mass-independent isotope fractionation in the O+CO reaction. We propose that all observations can be completely explained by an isotope transfer from ozone, involving photolytic production of O(1D) that in turn leads to OH radicals, which then rapidly form CO2 from reaction with CO. We also present a method to produce pure ozone samples and derive an upper limit on nitrogen oxide contaminations based on mass spectrometer measurements. These values will serve as benchmarks values for future studies of ozone absorption cross sections in the IR and UV.