Université d'Evry Val d'Essonne

XPS data processing for cobalt and nickel core-level peaks can be complicated. This is especially true when analyzing a mixture of oxide/oxyhydroxide/hydroxide compounds of these metals. The objective of this study is to develop a method for decomposing XPS spectra of 2p core levels for nickel and cobalt-oxidized compounds. This methodology was then employed to study the passivation layer of the Co₂₀Ni₈₀ alloy. The analysis of Ni_2p and Co_2p photo peaks using a homemade code based on core-level peak structure and satellites enables us to determine the chemical composition of the surface layer, knowledge of which is particularly important because it is directly linked to the anticorrosive properties it confers on the surface of the oxidized alloy. The XPS analysis, coupled with sequential ion sputtering, revealed that the passive layer of the Co₂₀Ni₈₀ alloy is heterogeneously covered with either oxidized cobalt compounds or oxidized nickel compounds. The method used also demonstrates that the chemical heterogeneity is associated with the thickness heterogeneity of the passive layer.

The combination of high volume of moderate-intensity continuous training with a low volume of high-intensity interval training improved body composition and physical capacities in individuals with obesity. However, polarized training (POL) has never been used in adult men with obesity. Thus, the purpose of this study was to investigate changes in body composition and physical capacities induced by a 24-week POL or threshold (THR) program in obese male adults. Twenty male patients (mean age 39.8±6.3 yrs; mean body mass index [BMI] 31.6±2.7 kg∙m−2) participated in this study (n: 10 POL, n: 10 THR). After 24-week, body mass (BM) and fat mass (FM) decreased by -3.20±3.10 kg (P<0.05) and -3.80±2.80 kg (P<0.05), respectively, similarly in both groups. Maximal oxygen uptake (  ̇VO2max) and   ̇VO2 at respiratory compensation point (RCP) increased in the POL group (+8.5±12.2 and+9.0±17.0%, P<0.05) and in the THR group (+4.24±8.64 and+4.0±6.70%, P<0.05), as well   ̇VO2 at gas exchange threshold (GET) increased similarly in both groups (+12.8±12.0%, P<0.05). POL and THR were equally effective in improving body composition and physical capacities in obese subjects. Future studies are needed to determine whether adherence to the training program can be improved by adding a running competition compared with a group without competition at the end of the training program.

The amphiphilic heterograft copolymers bearing biocompatible/biodegradable grafts [poly(2-methyl-2-oxazoline-co-2-pentyl-2-oxazoline)-g-poly(d-l-lactic acid)/poly(2-ethyl-2-oxazoline)] were synthesized successfully by the combination of cationic ring-opening polymerization and click chemistry via the ⟨"grafting to"⟩ approach. The challenge of this synthesis was to graft together hydrophobic and hydrophilic chains on a hydrophilic platform based on PMeOx. The efficiency of grafting depends on the chemical nature of the grafts and of the length of the macromolecular chains. The self-assembly of these polymers in aqueous media was investigated by DLS, cryo-TEM, and SANS. The results demonstrated that different morphologies were obtained from nanospheres and vesicles to filaments depending on the hydrophilic weight ratio in the heterograft copolymer varying from 0.38 until 0.84. As poly(2-ethyl-2-oxazoline) is known to be thermoresponsive, the influence of temperature rise on the nanoassembly stability was studied in water and in a physiological medium. SANS and DLS measurements during a temperature ramp allowed to show that nanoassemblies start to self-assemble in "raspberry like" primary structures at 50 °C, and these structures grow and get denser as the temperature is increased further. These amphiphilic heterograft copolymers may include hydrophobic drugs and should find important applications for biomedical applications which require stealth properties.