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Ground-State Structure and Excited-State Dynamics of a Donor–Acceptor Complex with Two Charge-Transfer Bands
No full textAlthough electron donor-acceptor complexes have been known for more than 70 years and are increasingly used in various applications, very little is still known about their structure in liquids. Here, we investigate the excited-state dynamics of a complex with two charge-transfer (CT) bands, which are usually discussed in terms of two distinct geometries, opening the possibility for photoselection. Apart from an initial ultrafast internal conversion to the lowest CT state upon high-energy band excitation, the ensuing dynamics do not depend on which CT transition has been excited, suggesting complexes of similar structures. The pure ground-state bleach dynamics, extracted using polarized transient absorption measurements, does not exhibit any hole-burning effect and is independent of the excitation wavelength, indicating an absence of photoselection. These results are rationalized using molecular dynamics simulations, which point to a broad distribution of structures with a significant oscillator strength for both transitions, contrary to the generally accepted picture
How I treat quantitative fibrinogen disorders
No full textQuantitative fibrinogen disorders, including afibrinogenemia and hypofibrinogenemia, are defined by the complete absence or reduction of fibrinogen, respectively. The diagnosis is based on the measurement of fibrinogen activity and antigen levels, which define the severity of this monogenic disorder. Afibrinogenemia is the result of homozygosity or combined heterozygosity for the causative mutations, whereas monoallelic mutations lead to hypofibrinogenemia. The bleeding phenotype varies in accordance with fibrinogen levels, ranging generally from frequent and often life-threatening bleeding in afibrinogenemia to the absence of symptoms, or mild bleeding symptoms in mild hypofibrinogenemia. The main treatment for quantitative fibrinogen disorders is fibrinogen supplementation. Despite low fibrinogen levels, a tendency for thrombosis is a characteristic of these disorders and may be exacerbated by fibrinogen supplementation. The management of surgery and pregnancy presents significant challenges regarding the amount of fibrinogen replacement and the need for thromboprophylaxis. The objective of this article is to present 4 clinical scenarios that illustrate common clinical challenges and to propose strategies for managing bleeding, thrombosis, surgery, and pregnancy
Drug-conjugate micelle systems for the targeted topical administration of anti-acne drugs to the skin
No full textThe aim of this PhD work was to improve the skin bioavailability of two compounds used in the treatment of acne by targeting the primary site of the disease: the pilosebaceous unit (PSU). The main idea was to synthesize a conjugate composed of an active compound and an amphiphilic polymer capable of self-assembling into micelles in aqueous media. Micelles offer several advantages, such as increasing the skin bioavailability of active compounds, and more importantly in our case, it has been shown that they can target skin appendages like the PSU. The specific objective of this work was to synthesize these conjugates and characterize them in terms of size, shape, stability, and micelle-forming capacity. Once these properties were established, the next step was to evaluate the micelles in contact with the skin and determine their ability to deliver the active ingredient. Another potential benefit of these conjugates is that they could also serve as carriers for other active ingredients, which is particularly relevant in the treatment of acne, where combination therapies are often used.</b
Eine Kirche im Wandel : Gerson-Lektüren am Vorabend der Reformation : der Fall von Jean Laillier
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Source-to-Sink Weathering Response to the Paleocene–Eocene Thermal Maximum (PETM) in the Southern Pyrenees and the Gulf of Mexico
No full textUnderstanding how Earth’s surface processes respond to extreme warming is critical for predicting long-term carbon cycle dynamics and the resilience of landscapes to rapid climatic change. Silicate weathering acts as a key negative feedback by sequestering CO₂ over geological timescales. The Paleocene–Eocene Thermal Maximum (PETM), a rapid global warming event ~56 Ma ago, offers a valuable natural experiment for assessing Earth’s response to abrupt climate perturbations.
This thesis investigates the silicate weathering response to the PETM across a source-to-sink transect in the Southern Pyrenees, a region with a semi-arid Paleocene–Eocene climate and exceptional preservation of diverse depositional environments. Using a multiproxy approach, the study reconstructs regional climate dynamics, evaluates continental weathering responses, traces the transfer of signals to the deep-marine sink, and compares the Pyrenean system with a more lithologically reactive setting on the North American continent recorded in the Gulf of Mexico. Integrated analyses of major and trace elements, clay mineralogy, and stable (δD, δ⁷Li, δ¹⁸O) and radiogenic (εNd, εHf) isotopes capture spatial and temporal variability in climate, weathering intensity, and denudation.
The results constrain the magnitude of temperature and precipitation perturbations in the Tremp-Graus basin, revealing intensified rainfall variability despite stable mean annual precipitation, and quantify temperature shifts in both sediment source and sink. Increased clay formation, together with enhanced sediment reworking, indicates a moderate, incongruent weathering regime in terrestrial to coastal settings (Esplugafreda and Rin). These patterns are echoed in the marine record at Campo and Zumaia, where δ⁷Li and ΔεHf (εNd–εHf decoupling) show coherent excursions, consistent with increased continental clay production and rapidly rising weathering fluxes and reworking. Comparisons with North America highlight the strong influence of initial climatic, lithologic, and geomorphic conditions on regional weathering responses. In more reactive settings, such as the Gulf of Mexico, weathering fluxes appear to increase substantially, potentially amplifying climate feedbacks.
By refining our understanding of climate–weathering feedbacks during the PETM, this thesis provides insights into how Earth’s surface processes may respond to anthropogenic global warming, underscoring the need to integrate geological perspectives into climate prediction and strategies for mitigating future extreme events.</p
The molecular regulation of H3K27me3 landscape and its inheritance in <i>Caenorhabditis elegans</i>
No full textOne of the most fascinating aspects of molecular and cellular biology is the ability of a zygote to develop into diverse cell types during development. Each of these cell types, despite containing identical genetic material, possesses highly specialized functions, showing that this difference must have a non-genetic basis. This is globally referred to as epigenetics that can be defined as gene regulatory systems affecting gene expression independent of DNA sequence.
Gene expression regulation by epigenetics can occur in several forms, from transcription to translation. While small noncoding RNAs posttranscriptionally and translationally act on mRNAs, transcriptional epigenetic regulations are chromatin-based and can be encoded by histones and their chemical posttranslational modifications (PTMs). For example, the methylation of histone H3 at position lysine 27 (H3K27me) is a facultative heterochromatin mark that plays a key role in cell differentiation. H3K27me3 PTMs decorate the chromatin and create an epigenetic memory that can be transmitted from parents to zygotes to the germ line of developing animals. Perturbation of its inheritance results in development and fertility defects in different species, underlying the importance of epigenetic inheritance (EI) of H3K27me3 genomic patterns. However, we have a limited understanding of the principles and mechanisms of the H3K27me3 inheritance. Currently, the biggest challenge to studying the inheritance of H3K27me3 is the absence of a tractable experimental setup for genetic and molecular investigations in vivo.</p
Diagnostic et prise en charge en urgence des incidents radiologiques
No full textIncidents involving ionizing radiation pose a risk of immediate and long-term clinical consequences for both victims and responders in the event of secondary contamination. Rapid identification of the problem and a coordinated response are crucial. This article summarizes the key challenges related to the emergency management of a single patient or multiple victims, addressing the importance of recognizing such a case, radioprotection measures, decontamination, and available treatments.Les incidents impliquant des rayonnements ionisants représentent un risque aux conséquences cliniques immédiates et à long terme, tant pour les victimes que pour les intervenants en cas de contamination secondaire. L’identification rapide de la problé- matique et une réponse coordonnée sont cruciales. Cet article résume les principaux enjeux liés à la prise en charge en urgence d’un patient unique ou de plusieurs victimes, en abordant l’importance de la reconnaissance d’un tel cas, des mesures de radioprotection, de la décontamination et des traitements disponibles