Comparative Microstructural Study of the Diffusion Zone Between Ni-Cr Alloy and Different Dental Ceramics

Detailed knowledge of bonding mechanisms, between the metal and ceramic parts in conventional dental systems, can help the development of new, improved systems and the optimisation of recent technologies. Despite their allergic potential, the NiCr alloys are still amongst the most often used dental materials so their investigation is important. The aim of the study was to carry out a detailed microstructural investigation and to compare the reaction layer developed between three different dental ceramics and NiCr alloy under different firing conditions. For the measurements six identical samples were cast from WIRON 99 (Bego, Konstantz, Germany) alloy. Ceramic opaquers were fired on the polished surface using Vision (Wohlwend AG), Vita VMK 95 (Vita) and Carat(DeTrey/Dentsplay) materials. Two samples were produced from each type of opaquers by different firing conditions. The TEM investigations were performed by using a 2000FX-II microscope with a Link-lsis EDS system. Similar growth processes of the phases were observed in all of the investigated systems in the sense that an amorphous phase was formed on the metal-ceramic interface producing bubble like inclusions on the metal surface. The main component of this phase is silicon oxide in the case of Carat and Vita ceramics, while in the case of Vision potassium and nickel oxides were observed after the normal firing process. In all systems and at all firing conditions a nanocrystalline Cr2O3 layer (with about 50 nm grain size) was commonly observed. This investigation was supported in part by ETT Grant 2001-3

TLR9 Agonist Protects Mice from Radiation-Induced Gastrointestinal Syndrome

Radiation-induced gastrointestinal syndrome (RIGS) is due to the clonogenic loss of crypt cells and villi depopulation, resulting in disruption of mucosal barrier, bacterial invasion, inflammation and sepsis. Intestinal macrophages could recognize invading bacterial DNA via TLR9 receptors and transmit regenerative signals to the neighboring crypt. We therefore investigated whether systemic administration of designer TLR9 agonist could ameliorate RIGS by activating TLR9.Male C57Bl6 mice were distributed in four experimental cohorts, whole body irradiation (WBI) (8.4-10.4 Gy), TLR9 agonist (1 mg/kg s.c.), 1 h pre- or post-WBI and TLR9 agonist+WBI+iMyd88 (pretreatment with inhibitory peptide against Myd88). Animals were observed for survival and intestine was harvested for histological analysis. BALB/c mice with CT26 colon tumors in abdominal wall were irradiated with 14 Gy single dose of whole abdominal irradiation (AIR) for tumor growth study.Mice receiving pre-WBI TLR9 agonist demonstrated improvement of survival after 10.4 Gy (p<0.03), 9.4 Gy (p<0.008) and 8.4 Gy (p<0.002) of WBI, compared to untreated or iMyd88-treated controls. Post-WBI TLR9 agonist mitigates up to 8.4 Gy WBI (p<0.01). Histological analysis and xylose absorption test demonstrated significant structural and functional restitution of the intestine in WBI+TLR9 agonist cohorts. Although, AIR reduced tumor growth, all animals died within 12 days from RIGS. TLR9 agonist improved the survival of mice beyond 28 days post-AIR (p<0.008) with significant reduction of tumor growth (p<0.0001).TLR9 agonist treatment could serve both as a prophylactic or mitigating agent against acute radiation syndrome and also as an adjuvant therapy to increase the therapeutic ratio of abdominal Radiation Therapy for Gastro Intestinal malignancies

Automated Reporter Quantification In Vivo: High-Throughput Screening Method for Reporter-Based Assays in Zebrafish

Reporter-based assays underlie many high-throughput screening (HTS) platforms, but most are limited to in vitro applications. Here, we report a simple whole-organism HTS method for quantifying changes in reporter intensity in individual zebrafish over time termed, Automated Reporter Quantification in vivo (ARQiv). ARQiv differs from current “high-content” (e.g., confocal imaging-based) whole-organism screening technologies by providing a purely quantitative data acquisition approach that affords marked improvements in throughput. ARQiv uses a fluorescence microplate reader with specific detection functionalities necessary for robust quantification of reporter signals in vivo. This approach is: 1) Rapid; achieving true HTS capacities (i.e., >50,000 units per day), 2) Reproducible; attaining HTS-compatible assay quality (i.e., Z'-factors of ≥0.5), and 3) Flexible; amenable to nearly any reporter-based assay in zebrafish embryos, larvae, or juveniles. ARQiv is used here to quantify changes in: 1) Cell number; loss and regeneration of two different fluorescently tagged cell types (pancreatic beta cells and rod photoreceptors), 2) Cell signaling; relative activity of a transgenic Notch-signaling reporter, and 3) Cell metabolism; accumulation of reactive oxygen species. In summary, ARQiv is a versatile and readily accessible approach facilitating evaluation of genetic and/or chemical manipulations in living zebrafish that complements current “high-content” whole-organism screening methods by providing a first-tier in vivo HTS drug discovery platform

On relations between the transformation temperatures, stresses, pressures and magnetic fields in shape memory alloys

December 3-5International audienc

Effect of hydrostatic pressures on thermoelastic martensitic transformations

Supposing that - according to the Clausius-Clapeyron equation - the volume change of the transformation is responsible for the pressure dependence of the equilibrium temperature To, and that the elastic energy term, eo, corresponding to the martensite start, Ms (and austenite finish, Af) temperatures, differs from zero as well, the pressure dependence of the elastic and dissipative energy terms of the martensitic and reverse transformations can be separated. It is illustrated by the example of our experimental results for the pressure effect on the transformations in Cu-22at%Zn-12at%Al-1at%Mn [l] as well as in near equiatomic NiTi shape memory alloys [2]. The elastic energy term, eo, showed different behaviour in the low-pressure range for samples of different pre-history, while at high pressures the pressure dependence of the elastic and dissipative terms showed a more general trend