Asymmetric allylation of carbonyl compounds: kinetic resolution of sec-allylboronates and total synthesis of natural products

Asymmetric allylation of aldehydes with stoichiometric allylmetal reagents has evolved into an efficient and well established methodology for the synthesis of enantiomerically enriched homoallylic alcohols. The use of enantioenriched secondary allylboronates gives rise to a mixture of E/Z homoallylic alcohols with the opposite configuration at the stereogenic centre (reaction 1). The first part of this thesis presents a novel and conceptually different solution to attain high stereoselectivity in the allylation of aldehydes with secondary allylboronates. The method revolves around an efficient kinetic resolution of chiral racemic allylboronates (reaction 2). Catalysis by a chiral Brønsted acid ensures a face- and Z-selective allylation of aldehydes. This asymmetric allylation has proved successful over a wide range of aldehydes with different electronic and steric properties. The methodology provides a shortcut to enantio- and diastereomerically enriched homoallylic alcohols finding a wide use in pharmaceutical and fine chemicals development. The second part of the present thesis describes the asymmetric total synthesis of two bioactive metabolites of the Pseudopterogorgiane elisabethae family, ()-elisabethadione and ()-erogorgiane. Three key reactions steps to introduce the stereogenic centres in the natural product scaffold include asymmetric allylation, oxy-Cope rearrangement and cationic cyclisation

Self-DNA Early Exposure in Cultivated and Weedy Setaria Triggers ROS Degradation Signaling Pathways and Root Growth Inhibition

The accumulation of fragmented extracellular DNA reduces conspecific seed germination and plantlet growth in a concentration-dependent manner. This self-DNA inhibition was repeatedly reported, but the underlying mechanisms are not fully clarified. We investigated the species-specificity of self-DNA inhibition in cultivated vs. weed congeneric species (respectively, Setaria italica and S. pumila) and carried out a targeted real-time qPCR analysis under the hypothesis that self-DNA elicits molecular pathways that are responsive to abiotic stressors. The results of a cross-factorial experiment on root elongation of seedlings exposed to self-DNA, congeneric DNA, and heterospecific DNA from Brassica napus and Salmon salar confirmed a significantly higher inhibition by self-DNA as compared to non-self-treatments, with the latter showing a magnitude of the effect consistent with the phylogenetic distance between the DNA source and the target species. Targeted gene expression analysis highlighted an early activation of genes involved in ROS degradation and management (FSD2, ALDH22A1, CSD3, MPK17), as well as deactivation of scaffolding molecules acting as negative regulators of stress signaling pathways (WD40-155). While being the first exploration of early response to self-DNA inhibition at molecular level on C4 model plants, our study highlights the need for further investigation of the relationships between DNA exposure and stress signaling pathways by discussing potential applications for species-specific weed control in agriculture

Placing land cover pattern preferences on the map. Bridging methodological approaches of landscape preferences surveys and spatial pattern analysis

This paper presents an innovative methodological framework – Landscape Preferences Spatial Framework (LPSF) – which is able to translate landscape preferences, as expressed by various users, concerning possible land cover pattern compositions into land cover pattern preference maps. The innovative potential of the contribution lies in the exploration of a comprehensive methodical framework that facilitates the spatial representations of landscape demands by relevant user groups thus bridging the gap between landscape preference research and landscape planning. The LPSF developed here goes beyond the state of the art in translating local scale preference by people into regional scale planning settings. Throughout the paper the development and testing of the LPSF is described and explained. Although the paper focuses on the conceptual framework of the method, it also shows the results of its application in a case study

Effects of Thermal Variations on the Tensile Behavior of FRCM Strengthening Systems

Use of fabric-reinforced cementitious matrices (FRCM) is a very efficient strengthening solution for improving the structural behavior of existing masonry elements. FRCM are capable of improving the load-bearing capacity of masonry panels, at the same time providing more ductile behavior. However, the mechanical performances of these materials could be significantly affected by environmental conditions, such as exposure to thermal variations. This aspect should be properly assessed by guidelines and standards devoted to the design of strengthening interventions. Within this framework, the objective of the present research was to evaluate the effect of a temperature increase on the tensile behavior of various FRCM systems, composed of steel, basalt, or aramid-glass fibers and lime-based or cement-based mortar matrices. Tensile tests were performed for each system under different thermal conditioning protocols, comprising different target temperatures, exposure periods, test conditions, and adopted heating sources. The test results showed that the effect of temperature is more evident in the first phases of the tensile tests, that is, during the uncracked phase and the mortar matrix cracking phase, whereas it is less significant in the final phase, which was more related to fiber behavior. Comparisons between the different thermal conditioning procedures are critically discussed within the paper and, in light of the results obtained, recommendations are included to optimize the testing procedures for future research and qualification procedures

Technical developments for computed tomography on the CENBG nanobeam line

The use of ion microbeams as probes for computedtomography has proven to be a powerful tool for the three-dimensional characterization of specimens a few tens of micrometers in size. Compared to other types of probes, the main advantage is that quantitative information about mass density and composition can be obtained directly, using specific reconstruction codes. At the Centre d’Etudes Nucléaires de Bordeaux Gradignan (CENBG), this technique was initially developed for applications in cellular biology. However, the observation of the cell ultrastructure requires a sub-micron resolution. The construction of the nanobeamline at the Applications Interdisciplinaires des Faisceaux d’Ions en Region Aquitaine (AIFIRA) irradiation facility has opened new perspectives for such applications. The implementation of computedtomography on the nanobeamline of CENBG has required a careful design of the analysis chamber, especially microscopes for precise sample visualization, and detectors for scanning transmission ion microscopy (STIM) and for particle induced X-ray emission (PIXE). The sample can be precisely positioned in the three directions X, Y, Z and a stepper motor coupled to a goniometer ensures the rotational motion. First images of 3D tomography were obtained on a reference sample containing microspheres of certified diameter, showing the good stability of the beam and the sample stage, and the precision of the motion

Chiral counterion strategy in Cu-catalyzed asymmetric allylic oxidation of linear alkenes

Application of a chiral counter-ion strategy in the Kharasch-Sosnovsky reaction is reported. Copper(I) phosphates obtained from axially chiral, BINOL-derived phosphoric acids were investigated as catalysts in the enantioselective allylic oxidation of acyclic alkenes. Good yields and high regioselectivity towards branched allylic ester have been achieved. The chiral phosphates investigated exhibited modest enantioselectivities

The Geant4-DNA project

The Geant4-DNA project proposes to develop an open-source simulation software based and fully included in the general-purpose Geant4 Monte Carlo simulation toolkit. The main objective of this software is to simulate biological damages induced by ionising radiation at the cellular and sub-cellular scale. This project was originally initiated by the European Space Agency for the prediction of deleterious effects of radiation that may affect astronauts during future long duration space exploration missions. In this paper, the Geant4-DNA collaboration presents an overview of the whole ongoing project, including its most recent developments already available in the last Geant4 public release (9.3 BETA), as well as an illustration example simulating the direct irradiation of a chromatin fibre. Expected extensions involving several research domains, such as particle physics, chemistry and cellular and molecular biology, within a fully interdiciplinary activity of the Geant4 collaboration are also discussed.Comment: presented by S. Incerti at the ASIA SIMULATION CONFERENCE 2009, October 7-9, 2009, Ritsumeikan University, Shiga, Japa

Aislamiento de microorganismos halófilos procedentes de ríos, pantanos y aguas residuales de la provincia de Granada

The purpose of this study was the isolation of halophilic micro-organisms from atipically satine environments located in different areas of Granada, Spain; we tried al so to know the number of viable cells per mL in these tested water samples. A total of 130 halophilic microorganisms was examined: 37.7% strains selected were halotolerant rods and they were isolated from rivers; 60.8% of isolated strains was classified as halophilic microorganisms and, in contrast of the majority ecologic stl.ldies conceming moderately halophilic bacteria, strains studied are grouped as Gram-positive.El presente trabajo se planteó con el objetivo de aislar microorganismos halófilos a partir de hábitats atípicamente salinos, tales como ríos, pantanos y aguas residuales de la provincia de Granada, realizando además una detenninación del número de aerobios totales mediante recuento de heterótrofos. Tras seleccionar 130 cepas al azar, el espectro salino nos confinnó que el número de bacterias halotolerantes era notable, el 37.7% y se aislaron principalmente de ríos. Los microorganismos halófilos hallados se clasificaron generalmente como moderados constituyendo el 60.8% de las cepas estudiadas, por lo que se confinna su presencia en dichos ecosistemas. Es importante señalar que el 69.2% del total son bacilos y cocos Gram positivos, el 11.5% presentaron un Gram variable y el 19.3% resultaron ser bacilos Gram negativos, distribución totalmente distinta a la descrita por numerosos autores al realizar estudios ecológicos de la microbiota halófila en medios hipersalinos

Allelic Variation of Wheat Flour Allergens in a Collection of Wheat Genotypes

Wheat is the most widely grown crop in the world and provides 20% of the daily protein and food calories for 4.5 billion people. Together with rice, it is the most important food crop in the developing world. In the last decades, various symptoms have been recorded across the population due to the consumption of wheat products, also summarized as "wheat allergy." Wheat allergy is usually reported as a food allergy but can also be a contact allergy as a result of exposure to wheat. Several important wheat allergens have been characterized in the last years through biochemical, immunological, and molecular biological techniques. In the present work, the identification of allelic variation of genes involved in wheat allergy was reported. A collection of wheat genotypes was screened in order to identify new alleles. A total of 14 new alleles were identified forprofilin, triosephosphate-isomerase, dehydrin, glyceraldehyde-3-phosphate-dehydrogenase,α/βgliadin, GluB3-23,andGlutathione transferaseallergen genes (located on chromosomes 1B, 3B, 6A, and homoelogous groups 5 and 7), potentially related to a minor allergenicity and useful in breeding programs