Protein Aggregation on Metal Oxides Governs Catalytic Activity and Cellular Uptake.

Engineering of catalytically active inorganic nanomaterials holds promising prospects for biomedicine. Catalytically active metal oxides show applications in enhancing wound healing but have also been employed to induce cell death in photodynamic or radiation therapy. Upon introduction into a biological system, nanomaterials are exposed to complex fluids, causing interaction and adsorption of ions and proteins. While protein corona formation on nanomaterials is acknowledged, its modulation of nanomaterial catalytic efficacy is less understood. In this study, proteomic analyses and nano-analytic methodologies quantify and characterize adsorbed proteins, correlating this protein layer with metal oxide catalytic activity in vitro and in vivo. The protein corona comprises up to 280 different proteins, constituting up to 38% by weight. Enhanced complement factors and other opsonins on nanocatalyst surfaces lead to their uptake into macrophages when applied topically, localizing >99% of the nanomaterials in tissue-resident macrophages. Initially, the formation of the protein corona significantly reduces the nanocatalysts' activity, but this activity can be partially recovered in endosomal conditions due to the proteolytic degradation of the corona. Overall, the research reveals the complex relationship between physisorbed proteins and the catalytic characteristics of specific metal oxide nanoparticles, providing design parameters for optimizing nanocatalysts in complex biological environments

Precise in situ measurements of isotopic abundances with pulse counting of sputtered ions

Ion counting with an electron multiplier (EM) is necessary when sputtered ions are used for in situ and precise isotopic abundance measurements (10−4 $(1\sigma)$) on small sample volume (about 100 μm3 for pure silicon). Measurements were performed on silicon samples bombarded with Cs+ ions by extracting negative secondary monatomic Si− ions. Pulse-height distributions (PHD) and isotopic ratios were used as diagnostic tools for repeatability studies. Repeatability could be greatly improved by determining the optimal position of the impact area on the conversion dynode and by addressing each isotopic beam properly focused on this area (adaptive optics). A simplified model based on Poisson's laws was developed to fit PHDs and allowed us to calculate quantum detection efficiencies versus thresholds. EM isotopic discriminations were determined with the resulting semiempirical algorithm so as to reconstruct the lost information and get data independent of threshold setting. To reach consistent results, quasi-simultaneous arrivals (QSA) on the conversion dynode had to be assumed and modelled using direct ionisation yields Si−/ Cs+ at different collection efficiencies. The QSA corrected data fitted well on the terrestrial isotopic fractionation line. Dead time uncertainties and possible emission non-linear isotopic fractionation processes were examined. PHDs from other elements and polyatomic ions were also discussed

Skew deviation : un accident vasculaire cérébral de la fosse postérieure jusqu’à preuve du contraire, illustré par deux cas cliniques

International audienc

SUPER: Visual Interfaces for Object + Relationship Data Models

SUPER is an exploratory project into the next generation of user-DBMS interfaces. Its main objective is to demonstrate that a visual paradigm can lead to powerful and user-friendly interfaces supporting all phases of the database life cycle (i.e. creation, manipulation and evolution). Visual interaction in SUPER is based on direct manipulation of objects and functions, with a special focus on providing users with maximum flexibility and independence from database technicalities. The set of tools offers facilities to meet the varied demands from categories of users with different levels of skill. Diagrammatic representations and a basic set of functions are better suited for novice and occasional users, while menus and dialog boxes speed up the dialog for expert users. At the same times a consistent interaction style over the various functions and tools has been emphasized. SUPER has been designed as a front end to a relational or an object-oriented DBMS, i.e. the persistence of data, consistency and concurrency problems are delegated to an off-the-shelf database management system. The current prototype supports schema definition, query formulation and browsing using a powerful data model based on objects and relationships