Diffusion-limited reactive wetting. spreading of Cu-Sn-Ti alloys on vitreous carbon.

International audienceThe substrate of com. available vitreous C was polished. The surface roughness of the substrate was sufficiently low not to influence wetting angle. The metal drops were prepd. from 99.999% pure Cu and Sn, and 99.7% purity Ti. The resulting alloy compn. was Cu-15at.%Sn-3at.%Ti. After the spreading expts. the measured contact angle (Q) as well as the drop base radius (R) were computed from the drop profile recorded on a videotape with an accuracy of +- 2 degree for Q and +- 2% for R. The expts. revealed that use of Cu-Sn-Ti led to a very good wetting on vitreous C. The final contact angle was close to 10 degree which is due to the formation of a continuous layer of Ti at the interface slightly < 0.5 mm. Curves of the R vs. time did not present a linear domain, indicating that spreading was not controlled by the local kinetics of interfacial reaction, but rather by diffusion of Ti from the drop bulk to the triple line

Investigation of the thermodynamic properties of Al4C3: A combined DFT and DSC study

International audienceThe question of material stability through the determination of the thermodynamic properties is of fundamental and technological importance to any analysis of system properties in many applications. For Al 4 C 3 , its experimental heat of formation varies widely, from −0.187 to −0.363 eV/atom, which makes it difficult to use such experimental information for any reactivity assessment. Here, we demonstrate that density functional theory (DFT), with the recently developed strongly constrained and appropriately normed (SCAN) functional, is especially powerful in critically assessing these experimental data. In order to have a more complete description of thermodynamic properties of Al 4 C 3 , we also determine the temperature dependence of its heat capacity using both the harmonic and quasi-harmonic approximation. In addition, and to select the most efficient approximation , we come back to the experimental background by using differential scanning calorimetry (DSC) to measure this quantity at constant pressure up to high temperatures, namely 873 K

Modelling kinetics of diffusion controlled reactive wetting: the role of reaction behind the triple line

Sessile drop experiments on metal/ceramic systems have shown that an important improvement in wetting may be produced by introduction of alloying elements which form, by reaction at the metal/ceramic interface, a continuous layer of solid that is better wetted by the metal than the original substrate. We present results from a finite-difference analysis of the kinetics of reactive wetting under conditions where the rate of spreading is controlled by the rate of diffusion of the reactive solute element

Evolution of serum Anti-Müllerian Hormone (AMH) level in young women treated with chemotherapy for breast cancer according to basal AMH level

International audienceObjective: Serum AMH level has been shown to decrease in women treated for breast cancer in several studies. However, whether basal AMH status affects AMH dynamics during chemotherapy remains to be clarified. The objective of this study was to compare serum AMH dynamics in young women with either low, normal or high basal serum AMH level at diagnosis, during and after treatment with chemotherapy for breast cancer.Study design: In this secondary analysis of a prospective cohort study, serum AMH was measured during and after chemotherapy in 239 women of reproductive age diagnosed with breast cancer and treated with chemotherapy. The association between AMH dynamics throughout chemotherapy and during follow-up and basal AMH status, i.e. low AMH (36 pmol/l), was evaluated. Menses occurrence was also recorded.Results: A total of 21 women had low, 154 had normal and 64 had high basal AMH level. Serum AMH rapidly decreased during chemotherapy in all groups, and its variation during chemotherapy and follow-up was not significantly different between the 3 groups.Conclusion: No association was found between AMH variation during chemotherapy and follow-up, and basal AMH level at diagnosis. However, women with high basal AMH levels have significantly higher AMH levels throughout chemotherapy and follow-up than women with normal or low basal AMH levels at diagnosis

Shape memory thin strips produced by the twin roll casting technique

A promising direct method of preparation by rapid solidification, the twin roll casting technique, bas been used for the first time to produce semi-finite shape memory alloys thin strips (200-600 $\mu$m thick). Different NiTi and Cu-Ni-Al based compositions have been tested. Some cracks appeared on these new products but they have been partially or totally suppressed, according to the alloy composition, by optimisation of the parameters of the process and after adding side dams to the wheels. The resulting strip morphology, structure and microstructure have been analyse, taking into account the complex heat and mass flows during the process. Transformation temperatures are in the same range of values that those of the corresponding massive materials