Investigation of Chemistry at Ice-Mineral Interfaces of Phosphorus-Containing Meteorites Analogues

The search for life outside of Earth has raised questions about how life began have intrigued origin-of-life researchers, such as the incorporation of phosphorus into biomolecules. Phosphorus exists on Earth mostly as phosphate, PO43-, which is insoluble and unreactive in the geochemical conditions of the early Earth. The challenge of incorporating phosphorus into biomolecules is known as the “phosphorus problem,” prompting investigations of reactive phosphorus species delivered to the prebiotic Earth. Phosphorus-laden meteorites delivered schreibersite (Fe,Ni)3P, a possible mineral source of phosphorus recognized for its redox chemistry potential and observed reactivity with aqueous solutions. This thesis work aims to better understand the chemical reactions occurring on the schreibersite inclusions on comets and meteorites and will focus on 1) identifying potential prebiotic phosphorus species formed at the ice-mineral interface of schreibersite, and 2) the energy requirements necessary for the abiotic formation of phosphorus-containing compounds. Specifically, the reactions of water and methanol ices on a schreibersite analogue will be investigated upon heating and irradiation with tuneable, low-energy electrons in ultrahigh vacuum conditions, utilizing reflection-absorption infrared spectroscopy (RAIRS) to measure changes in surface structure and mass spectrometry (MS) to analyze species desorbing from the mineral surface. These experiments attempt to identify abiotic pathways in which phosphorus is incorporated into prebiotic reactions, and are intended to provide reference spectra for solar system mission data. Preliminary results obtained from these experiments will be presented

On the Sum of AlI N-commutators in a Finite Group

In the theory of nonassociative algebras - like Lie algebras, alternative algebras, Jordan algebras - the Casimir operator is a useful tool in proving some important theorems. In my Iecture I wiU discuss the Casimir operator in finite group algebras to give simple and elegant proofs of some nown and unknown basic facts from group theory

Conserved key players required for Physcomitrella patens male fertility are affected by accumulation of (epi-) mutations

Physcomitrella patens belongs to the bryophytes and is an extant species of the first land plants. This phylogenetic informative position allows the analysis of key evolutionary steps in (land) plant evolution employing P. patens as a model organism. Decades of research mainly focused on the gametophytic generation, probably also due to the lack of sexual reproductive events in the primarily used ecotype Gransden. Long term in vitro vegetative reproduction probably led to the accumulation of somatic (epi-) mutations which eventually led to a nearly male sterile phenotype. So far, only few P. patens ecotypes are used for scientific work. Thus, to overcome the fertility issues and to apply comparative analyses to study sexual reproduction and sporophyte development as well as species and population divergence in P. patens, the establishment of more ecotypes is highly needed. In comparison to other plant model organisms as e.g. Arabidopsis thaliana, genome wide epigenetic modifications especially with regard to sexual reproduction are still barely studied in P. patens ecotypes. Here I present the characterization of the sexual reproduction of the recently introduced fertile ecotype Reute which was collected 2006 in Germany. Reute is the most closely related ecotype to Gransden reported so far. In a comparative analysis between the ecotypes Gransden, Reute and Villersexel, I could show no differences in timing and morphology of the sexual reproductive tissues. However, while Reute was as fertile as the more distant ecotype Villersexel, Gransden was nearly self-sterile. Also, I present the fluorescent marker strain Reute-mCherry which can be used in crossing analyses e.g. to determine if female or male sexual reproductive organs are impaired. By employing this method, a clear male defect could be shown in Gransden. Further, I present a comparative multi-omics analysis between Gransden and Reute using different tissues during sexual reproduction. Single nucleotide polymorphisms (SNPs), DNA-methylation and RNA-expression pinpoint a flagellar defect, which presumably leads to the observed male fertility impairment in Gransden. Finally, I present the characterization of key-players which are highly conserved within eukaryotes and are required for flagellar motility in humans as well as in the moss P. patens

On characteristic equations, trace identities and Casimir operators of simple Lie algebras

Two approaches are developed to exploit, for simple complex or compact real Lie algebras g, the information that stems from the characteristic equations of representation matrices and Casimir operators. These approaches are selected so as to be viable not only for `small' Lie algebras and suitable for treatment by computer algebra. A very large body of new results emerges in the forms, a) of identities of a tensorial nature, involving structure constants etc. of g, b) of trace identities for powers of matrices of the adjoint and defining representations of g, c) of expressions of non-primitive Casimir operators of g in terms of primitive ones. The methods are sufficiently tractable to allow not only explicit proof by hand of the non-primitive nature of the quartic Casimir of g2, f4, e6, but also e.g. of that of the tenth order Casimir of f4.Comment: 39 pages, 8 tables, late

Aplicación de sistemas de visión por computador (VIR/NIR) para la inspección visual de uchuvas

Desarrollo de un prototipo de un sistema de inspección visual de uchuvas en el CTAI de la Pontifícia Universidad Javeriana a través de la aplicación de sistemas de visión por computador (VIR/NIR).Ingeniero (a) IndustrialPregrad

Aplicação de métodos probabilísticos para a avaliação da confiabilidade de funções transmissão sujeitas à parcela variável

A proposta deste trabalho é a aplicação de métodos probabilísticos para a avaliação da confiabilidade de instalações sujeitas aos descontos referidos, face aos padrões estipulados e possíveis deduções, como uma forma de auxílio ao projeto e gestão das mesmas. Neste trabalho são apresentados os aspectos da regulação da qualidade do serviço de transmissão, a metodologia desenvolvida, as ferramentas probabilísticas a qual foi fundamentada e um exemplo de aplicação a um caso real

The Investigation of Geologically Relevant Metal Phosphites as a Plausible Source of Phosphorus in Prebiotic Chemistry

To understand the origin of life, the abiotic incorporation of phosphorus in energy-promoting molecules like adenosine triphosphate (ATP) need to be identified. However, a consensus has not been reached on the source of phosphorus for prebiotic chemistry on Archaean Earth. One hypothesis is that metal phosphites were an important source of phosphorus for prebiotic chemistry. The primary issue with this hypothesis is the lack of phosphites in the geological rock record, where different phosphorus compounds (mostly inorganic phosphates) are observed instead. Two geologically relevant metal phosphites with varying waters of hydration, CaHPO3 and MgHPO3, were synthesized, structurally characterized, and thermally processed to determine if the conditions on early Earth could explain the lack of phosphite in the geological record. The phosphites were characterized using Thermogravimetic Analysis, X-Ray Diffraction, and phosphorus Nuclear Magnetic Resonance. From these experiments, interstitial waters associated with the metal phosphites are dehydrated from the compounds, which influences their reactivity. From Thermogravimetric Analysis, and phosphorus Nuclear Magentic Resonance data, simultaneous polymerization and oxidation is observed defining reactivity. Also, X-Ray Diffraction data validated the synthesis of metal phosphites in the lab. Since they are subject to polymerize and oxidize at higher temperatures in different environments, metal phopshites may not easily preserved in the geological rock record. Preliminary data to support this investigation will be presented here

Hydrops fetalis with isolated massive ascites in a preterm neonate with rhesus disease

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