Protein Inhibitors of Calcium Salt Crystal Growth in Saliva, Bile and Pancreatic Juice

The control of the formation of crystals in biological fluids is one of the most exciting field of research involving both organic and biochemical areas. Many organisms have evolved mechanisms which minimize or avoid the effects of nucleation and crystal growth formation. One of the most important mechanism is the interaction of specific proteins, called inhibitors, with crystals which alters their habits and leads to their elimination. This article, focused on saliva, pancreatic juice and bile, reviews our present knowledge on the structure-function relationships existing between these proteins and their ability to inhibit the growth of different calcium salt crystals

Sound and light from fractures in scintillators

Prompted by intriguing events observed in certain particle-physics searches for rare events, we study light and acoustic emission simultaneously in some inorganic scintillators subject to mechanical stress. We observe mechanoluminescence in ${Bi}_4{Ge}_{3}{O}_{12}$, ${CdWO}_{4}$ and ${ZnWO}_{4}$, in various mechanical configurations at room temperature and ambient pressure. We analyze how the light emission is correlated to acoustic emission during fracture. For ${Bi}_4{Ge}_{3}{O}_{12}$, we set a lower bound on the energy of the emitted light, and deduce that the fraction of elastic energy converted to light is at least $3 \times 10^{-5}$

Peculiar scaling of self-avoiding walk contacts

The nearest neighbor contacts between the two halves of an N-site lattice self-avoiding walk offer an unusual example of scaling random geometry: for N going to infinity they are strictly finite in number but their radius of gyration Rc is power law distributed, ~ Rc^{-\tau}, where \tau>1 is a novel exponent characterizing universal behavior. A continuum of diverging lengths scales is associated to the Rc distribution. A possibly super-universal \tau=2 is also expected for the contacts of a self-avoiding or random walk with a confining wall.Comment: 4 pages, 5 Postscript figures, uses psfig.sty; some sentences clarifie

D028 L’expression des gènes PAI-1, tPA et uPA est fortement régulée pendant la différenciation des cellules souches embryonnaires en myocytes et adipocytes

PAI-1 est l’inhibiteur physiologique des activateurs du plasminogène uPA et tPA et inhibe le complexe formé entre uPA et son récepteur, et par voie de conséquence, entre la vitronectine et l’intégrine alphav beta3. PAI-1 est impliqué dans l’adhésion et la migration des cellules endothéliales, dans la différenciation adipocytaire et dans la réponse à l’insuline; in vivo, il facilite la thrombose, la fibrose et le remodelage tissulaire. Des taux élevés circulants de PAI-1 représentent un biomarqueur de l’obésité centrale et sont un facteur pronostic du diabète de type 2. Les propriétés biologiques de PAI-1 ont conduit à l’hypothèse que PAI-1 serait impliqué directement dans le développement du tissu adipeux. Notre objectif est d’évaluer les rôles spécifiques des gènes PAI-1, uPA et tPA dans les mécanismes moléculaires de la différenciation des cellules souches embryonnaires (cellules ES) de souris dans différents lignages.Indétectables à l’état indifférencié, les expressions de PAI-1, uPA et tPA et les activités enzymatiques uPA et tPA sont fortement régulées durant la différenciation des cellules ES. Les activités uPA et tPA sont rapidement augmentées durant la phase précoce de détermination du processus, sans expression détectable de PAI-1. Puis, l’expression de PAI-1 augmente progressivement dans les surnageants de culture des cellules bien différenciées, corrélant avec une inhibition concomittante des activités uPA et tPA. Des expériences d’immunohistochimie montrent que PAI-1 est exprimé à la fois dans les myotubes et dans les adipocytes matures.Le rôle potentiel de ces régulations successives est analysé par la construction de lignées de cellules ES surexprimant le cDNA de PAI- 1 dès l’état indifférencié. Les effets d’une surexpression ectopique de PAI-1 à différent temps pendant la différenciation des cellules ES sont recherchés.De plus, le traitement précoce des cellules ES en différenciation par l’amiloride, inhibiteur spécifique d’uPA, provoque une diminution de la myogénèse et une augmentation de la différenciation adipocytaire. Par contre ces effets ne sont pas retrouvés en traitant les cellules par l’EACA, inhibiteur de la plasmine ou le DMA, un dérivé inactif de l’amiloride

Hyperspectral imaging to characterize table grapes

Table grape quality is of importance for consumers and thus for producers. Its objective quality is usually determined by destructive methods mainly based on sugar content. This study proposed to evaluate the possibility of hyperspectral imaging to characterize table grapes quality through its sugar (TSS), total flavonoid (TF), and total anthocyanin (TA) contents. Different data pretreatments (WD, SNV, and 1st and 2nd derivative) and different methods were tested to get the best prediction models: PLS with full spectra and then Multiple Linear Regression (MLR) were realized after selecting the optimal wavelengths thanks to the regression coefficients (coefficients) and the Variable Importance in Projection (VIP) scores. All models were good at showing that hyperspectral imaging is a relevant method to predict sugar, total flavonoid, and total anthocyanin contents. The best predictions were obtained from optimal wavelength selection based on coefficients for TSS and from VIPs optimal wavelength windows using SNV pre-treatment for total flavonoid and total anthocyanin content. Thus, good prediction models were proposed in order to characterize grapes while reducing the data sets and limit the data storage to enable an industrial use

Paper Session I-C - Non-Destructive Detection of Corrosion Under Paint on Critical Surfaces

We describe our proof-of-concept demonstration of the well-known thermal diffusion imaging technique *\u3e 2\u3e3 for detection of corrosion under paint on critical surfaces. Our first application will be the detection and mapping of corrosion on arbiter vehicle wing spars and rudder speed brakes. The technique will also used for the evaluation of doubler plate bond integrity on the rudder speed brakes

Adsorption-like Collapse of Diblock Copolymers

A linear copolymer made of two reciprocally attracting N-monomer blocks collapses to a compact phase through a novel transition, whose exponents are determined with extensive MC simulations in two and three dimensions. In the former case, an identification with the statistical geometry of suitable percolation paths allows to predict that the number of contacts between the blocks grows like $N^{9/16}$. In the compact phase the blocks are mixed and, in two dimensions, also zipped, in such a way to form a spiral, double chain structure.Comment: 4 pages, 5 Postscript figure

The SciCryo Project and Cryogenic Scintillation of Al2O3Al_2O_3 for Dark Matter

International audienceWe discuss cryogenic scintillation of Al2O3. Room-temperature measurements with α particles are first carried out to study effect of Ti concentration on response. Measurements under X-rays between room temperature and 10 K confirm a doubling of light output. The integration of a scintillation-phonon detector into an ionization-phonon dark matter search is underway, and the quenching factor for neutrons has been verified