Influence of the synthetic method on the properties of two-photon-sensitive mesoporous organosilica nanoparticles

International audienceHerein we report the modulation of the properties of mesoporous silica nanoparticles (NPs) via various synthetic approaches. Three types of elaborations were compared, one in aqueous media at 25 °C, and the other two at 80 °C in water or in a water–ethanol mixture. For all these methods, an alkoxysilylated two-photon photosensitizer (2PS) was co-condensed with tetraethylorthosilicate (TEOS) in the presence of cetyltrimethylammonium bromide (CTAB), leading to five two-photon-sensitive mesoporous silica (M2PS) NPs. The M2PS NP porous structure could be tuned from radial to worm-like and MCM-41 types of organization. Besides, the 2PS precursor spatial dispersion was found to be highly dependent on both the 2PS initial concentration and the elaboration process. As a result, two-photon properties were modulated by the choice of the synthesis, the best results being found in aqueous media at 25 or 80 °C. Finally, the M2PS NPs were used for in vitro two-photon imaging of cancer cells

Adiponectin normalization: a clue to the anti-metabolic syndrome action of rimonabant.

International audienceObesity, currently associated with metabolic syndrome is characterized by an excessive fat storage in different organs, in particular adipose tissue, inducing the loss of its structural and functional integrity. Being aware of the importance of adipose tissue endocrine function and the key role of adipocytokines, such as adiponectin, in obesity and metabolic syndrome drives the necessity to develop new drugs that can exert a specific action on adipose tissue and on adiponectin levels. Rimonabant, an antiobesity drug, presents a dual effect by decreasing food intake and importantly increasing adiponectin. This review focuses on the key role of adiponectin regulation in the success of rimonabant and suggests that this adipohormone may be considered as a therapeutic target to design innovative and promising antiobesity and anti-metabolic syndrome drugs

Combination treatment with proteasome inhibitors and antiestrogens has a synergistic effect mediated by p21WAF1 in estrogen receptor-positive breast cancer

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On the fracture of Multi-crystalline silicon wafer

International audienceThis work focuses on the fracture behavior of multi-crystalline silicon in 4-point bending tests. The objective is to investigate the crack path as well as the effect of the grain boundary on the crack propagation. Thin specimens that contain the same grains have been tested under identical loading in order to assess the consistency of the fracture process. Fractography analysis has been carried out with a confocal microscope to describe the crack propagation within grains and at grain boundaries. The fracture paths have been also compared to X-FEM numerical simulations, and a very good agreement was found. Fractographies have been used to identify the cleavage planes in locations where surface instabilities are observed, and to reveal how grain boundaries are crossed. Laue x-ray diffraction analysis has been carried out to measure the grain orientations and further identify the cleavage planes in the areas far from instabilities and grain boundaries. It is observed that the fracture of multi-crystalline silicon is completely determinist, i.e. the same crack path for twin silicon plates, with the crack propagating mainly on the crystallographic plane $(1\,1\,1)$ and eventually on $(1\,1\,0)$ . The misorientation across the grain boundary can drive the crack away from the lowest surface energy plane. Another interesting observation is that the grain boundary slows down or stops shortly the crack propagation

A novel approach to control gray level of image invariant during near infrared thermography

International audienceKinematic and thermal field measurements can provide rich information in the field of thermo-mechanics of materials and structures (e.g., constitutive model identification, fatigue behavior investigation, cracking detection, etc.). Up to now, silicon based sensor cameras (CCD and CMOS) have been widely used to perform in situ observation of the kinematic field on the material surfaces, mainly thanks to image correlation or interferometry. Thermal fields are usually obtained thanks to dedicated Infrared Cameras. Nevertheless, the acquirement of thermal fields using a silicon based sensor visible camera is possible and suitable for application at high temperature. In this study, a low-cost, high-resolution and contactless field measurement protocol is proposed to in-situ observe temperature distribution. Actually, silicon based sensor visible cameras are also sensitive in the near infrared spectral band (0.7-1.1 μm). In this spectral range, a temperature evolution readily results in a modification of the gray level obtained with the camera. It is usually considered as issues on the acquired images (saturation or poor dynamic range of gray levels) for visible acquisitions. Then adjust the exposure time of the camera with temperature evolution is a suitable method to maintain the gray level of image constant. In this work, we propose an approach to precisely and continuously adjust the exposure time to get a constant gray level of images whatever the temperature evolution. Black body experiments have been conducted to verify the approach

A new experimental setup for high temperature creep test on Zircaloy-4 fuel rods internally pressurized

International audienceCustom experimental setup has been designed to investigate the secondary creep behavior of Zircaloy-4 cladding under Loss Of Coolant Accident (LOCA) conditions. Creep test are ran at elevated temperatures (from 700 to 900 °C) and the fuel rods are internally pressurized from 10 to 50 bars. The proposed setup induces a non-uniform axial temperature profile. At such temperatures the creep behavior is known to be strongly dependent on the temperature. Two dimensional Digital Image Correlation (2D-DIC) is performed using a custom optical system to compute kinematics data along the axial direction. Near Infra-Red (NIR) method has been developed to measure the temperature distribution. The correlation between the kinematics and thermal profiles is a good way to experimentally determine creep behavior parameters such as activation energy or stress exponent. The setup, its associated methods and results are detailed in this paper

A novel approach to control gray level of image invariant during near infrared thermography

International audienceKinematic and thermal field measurements can provide rich information in the field of thermo-mechanics of materials and structures (e.g., constitutive model identification, fatigue behavior investigation, cracking detection, etc.). Up to now, silicon based sensor cameras (CCD and CMOS) have been widely used to perform in situ observation of the kinematic field on the material surfaces, mainly thanks to image correlation or interferometry. Thermal fields are usually obtained thanks to dedicated Infrared Cameras. Nevertheless, the acquirement of thermal fields using a silicon based sensor visible camera is possible and suitable for application at high temperature. In this study, a low-cost, high-resolution and contactless field measurement protocol is proposed to in-situ observe temperature distribution. Actually, silicon based sensor visible cameras are also sensitive in the near infrared spectral band (0.7-1.1 μm). In this spectral range, a temperature evolution readily results in a modification of the gray level obtained with the camera. It is usually considered as issues on the acquired images (saturation or poor dynamic range of gray levels) for visible acquisitions. Then adjust the exposure time of the camera with temperature evolution is a suitable method to maintain the gray level of image constant. In this work, we propose an approach to precisely and continuously adjust the exposure time to get a constant gray level of images whatever the temperature evolution. Black body experiments have been conducted to verify the approach