Mesoscopic Strain Fields Measurement During the Allotropic α − γ Transformation in High Purity Iron

The allotropic phase change from ferrite to austenite represents a moment of massive interplay between the microstructural and mechanical states of iron. The difference of compacity between the two phases induces a microplastic accommodation in the material at grain scale. However, mechanical heterogeneities resulting from the transformation process remain challenging to characterise due to the high temperature conditions it is associated with. We developed experimental equipment for in situ observation of α ? γ and γ ? α transformations. Images of the surface of an iron sample taken by an optical camera were used as input for a Digital Image Correlation (DIC) routine. Special care was taken to maximize image resolution to capture sub-grain phenomena. Observations show that, at the mesoscopic scale, shear strain fields exhibit strong localisations that are evidence of transformations that are occurring.

     

Intravascular ultrasound allows a hyperplasia diagnosis in vivo in rat as accurate as histomorphometry

Objective and motivation

Intravascular ultrasound (IVUS) allows in vivo invasive intra-luminal real-time examination of the arterial wall structure. In this study, we aimed to validate for the first time the in vivo IVUS performing as a diagnostic tool by comparison to the well-established histomorphometry approach, in the largely used rat model of carotid angioplasty model that mimics the angioplasty procedure in humans.

Methods

Atherosclerotic lesions were allowed to develop during four weeks after balloon catheter inflation of the left carotid artery, whereas the intact right carotid artery was used as control. Four weeks after injury, a Boston Scientific 40 MHz device to perform IVUS exams in vivo on both carotid arteries. Then, both carotid arteries were examined in vitro by histomorphometry and correlation between IVUS and histomorphometric parameters (plaque plus media cross-sectional areas [CSA] and eccentricity index) were researched.

Results

After ANOVA analysis, comparative statistical analysis showed significant correlations between IVUS and histomorphometry when examining the intact right carotid artery (r = 0.662 with p < 0.003 for plaque plus media CSA; r = 0.774 with p < 0.002 for eccentricity index), but also when exploring the injured left carotid artery (r = 0.805 with p < 0.0001 for plaque plus media CSA; r = 0.775 with p < 0.002 for eccentricity index).

Conclusions and outcome

We report here for the first time the ability of IVUS to study therapeutic vascular effects in vivo in alive rats. This result is of major importance since it will allow this device to be used for restenosis drug testing in rat model of carotid angioplasty.     

Access to L- and D-iminosugar C-glycosides from a D-gluco-derived 6-azidolactol exploiting a ring isomerization/alkylation strategy

A flexible synthetic access to six-membered L- and D-iminosugar C-glycosides is reported starting from the easily available 6-azido-6-deoxy-2,3,4-tri-O-benzyl-D-glucopyranose precursor. This methodology involves a highly diastereoselective tandem ring enlargement/alkylation and a stereocontrolled ring contraction. It allows an efficient synthesis of iminosugar C-glycosides displaying structural diversity at both C-1 and C-6.     

Fully biodegradable polymeric micelles based on hydrophobic‐ and hydrophilic‐functionalized poly(lactide) block copolymers

Novel amphiphilic diblock copolymers from a combination of hydrophobic‐functional poly(lactides) (PLAs) with hydrophilic‐functional PLAs or poly(malic acid), respectively, toward fully biodegradable materials for medical applications, such as micellar drug delivery systems, are reported for the first time. The presented PLA‐based polymeric micelles are characterized by their small size below 100 nm, low critical micellar concentrations, good in vitro stabilities at room and body temperature, and efficient incorporation capability of hydrophobic compounds, particularly with regard to potential drug substances. Moreover, the advantage of being totally degradable with different rates at different pH values, as investigated in medical cancer treatment, is demonstrated. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3244–3254, 2010