Liquid–liquid extraction of thorium(IV) by fatty acids: a comparative study

In this paper, extractants that have the potential to be sustainably regenerated, are proposed for thorium(IV) removal from nitrate aqueous phases. These extractants are oleic (OA), palmitic (PA) and lauric (LA) acids. The advantages of using these acids are their sustainability, their biocompatibility and their non-toxicity, this makes these simpler and greener compared to other extractants (organophosphorus, azote derivatives, macrocyclic crown, etc…) used for metal extraction. These acids were applied as chelating agent for Th(IV) liquid–liquid extraction. The extractions were carried out in chloroform as an organic phase through the formation of thorium–OA, thorium–PA and thorium–LA complexes. The synergistic extraction of Th(IV) with these extractants in the presence of tributhylphosphine (TBP) has been investigated. The effect of different variables, such as time contact, pH of the aqueous phase, concentration of fatty acid, TBP addition on fatty acids, ionic strength and temperature, is reported. The results showed that the extraction kinetics using LA and OA were fast than with PA. The KNO₃ addition does not seem to highly influence the extraction yield, and no important synergy effect was noticed in the presence of TPB. Thermodynamic data for Th(IV) solvent extraction are also reported in this paper.     

A new sorbent for uranium extraction: Polyethyleniminephenylphosphonamidic acid

A new sorbent, polyethyleniminemethylenephosphonamidic acid (PEIPPA), was synthesized from commercially available polyethylenimine and P,P-dichlorophenylphosphine oxide. After characterization by (¹H, ¹³C, ³¹P) NMR and FTIR, the new ion-exchange polymer has been investigated in liquid-solid extraction of uranium. The extraction strongly depends on the pH, initial concentration of uranium, extractant to analyte ratio (mol/mol), ionic strength of the liquid medium and their mutual interactions. Such interactions were investigated through factorial 3³ experimental designs in order to achieve the best conditions of batch sorption procedure, obtaining the mutual interaction among variables and optimizing these variables. The recovery of U(VI) is almost quantitative.     

10 Hz flicker improves recognition memory in older people

Background  

10 Hz electroencephalographic (EEG) alpha rhythms correlate with memory performance. Alpha and memory decline in older people. We wished to test if alpha-like EEG activity contributes to memory formation. Flicker can elicit alpha-like EEG activity. We tested if alpha-frequency flicker enhances memory in older people. Pariticpants aged 67–92 identified short words that followed 1 s of flicker at 9.0 Hz, 9.5 Hz, 10.0 Hz, 10.2 Hz, 10.5 Hz, 11.0 Hz, 11.5 Hz or 500 Hz. A few minutes later, we tested participants' recognition of the words (without flicker).     

Reactivity of N‐benzyl‐3‐nitrophthalimide: A facile access to isoindolo[1,2‐d][3,5]benzothiazocine derivatives

A functionalized isoindolo[1,2‐d][3,5]benzothiazocine 2B has been synthesized in three steps from the nitro‐imide derivative 5. The key step of this sequence was the cyclization of the thioglycolic acid derivative 9 under acidic conditions. An evaluation of the reactivity of the imide 5 and the corresponding N‐acyliminium ion toward borohydride reduction, organometallic addition, Meyer‐Schuster rearrangement and intermolecular alkoxylation and thioalkoxylation reactions was reported.     

Melt strengthening of poly (lactic acid) through reactive extrusion with epoxy-functionalized chains

Poly (lactic acid) is an industrially mature, bio-sourced and biodegradable polymer. However, current applications of this eco-friendly material are limited as a result of its brittleness and its poorly melt properties. One of the keys to extend its processing window is to melt strengthen the native material. This paper considers the chain extension as a valuable solution for reaching such an objective. An additive based on epoxy-functionalized PLA was employed during reactive extrusion. The reaction times as a function of chain extender ratios were determined by monitoring the melt pressure during recirculating micro-extrusions. Once residence times were optimized, reactive extrusion experiments were performed on a twin screw extruder. Size exclusion chromatography provided information about the molecular weight distributions (MWD) of the modified PLAs and revealed the creation of a high molecular weight shoulder. The rheological experiments highlighted the enhancement of the melt properties brought about by the chain extension. Shear rheology revealed some enlarged and bimodal relaxation time spectra for the extended materials which are in accordance with the MWD analysis. Such a modification directly amplified the shear sensitivity of modified PLAs. Regarding the rheological temperature sensitivity, it was found to be decreased when the chain extender content is raised as shown from the Arrhenius viscosity fit. The reduction of the polar interactions from neat to highly chain-extended PLAs is here proposed to explain this surprising result. Chain extension was also found to impact on the elongational melt properties where strain hardening occurred for modified PLAs. Investigation of the chain extension architecture was made from the rheological data and revealed a long-chain branched topology for the modified PLAs.     

Lipschitz behavior of convex semi-infinite optimization problems: a variational approach

In this paper we make use of subdifferential calculus and other variational techniques, traced out from [Ioffe, A.D.: Metric regularity and subdifferential calculus. Uspekhi Mat. Nauk 55, 3(333), 103–162; Engligh translation Math. Surveys 55, 501–558 (2000); Ioffe, A.D.: On rubustness of the regularity property of maps. Control cybernet 32, 543–554 (2003)], to derive different expressions for the Lipschitz modulus of the optimal set mapping of canonically perturbed convex semi-infinite optimization problems. In order to apply this background for obtaining the modulus of metric regularity of the associated inverse multifunction, we have to analyze the stable behavior of this inverse mapping. In our semi-infinite framework this analysis entails some specific technical difficulties. We also provide a new expression of a global variational nature for the referred regularity modulus.      

Qualification conditions for multivalued functions in Banach spaces with applications to nonsmooth vector optimization problems

In this paper we introduce qualification conditions for multivalued functions in Banach spaces involving the A-approximate subdifferential, and we show that these conditions guarantee metric regularity of multivalued functions. The results are then applied for deriving Lagrange multipliers of Fritz—John type and Kuhn—Tucker type for infinite non-smooth vector optimization problems.     

Rheological,morphological, and interfacial properties of compatibilized PLA/PBAT blends

The focus of this paper was to gain a true understanding of the impact of a multifunctional epoxide (Joncryl®;ADR-4368) on the interfacial properties of biopolymer blends based on poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT). The effect of Joncryl on the shear rheological, morphological, and interfacial properties of the blends was systematically investigated. For the deformed drop retraction experiments, different sandwich model systems (droplet/matrix), representing various scenarios of compatibilization, were prepared, aiming to probe the role of the epoxy-functionalized chains on the interface. The decrease of the interfacial tension in the modified/compatibilized PLA_PBAT and the formation of the PLA-Joncryl-PBAT copolymer were highlighted. A new relaxation peak relative to this copolymer was detected by the relaxation spectrum. Transient start-up shear and nonlinear stress relaxation experiments were carried out and confirmed the obtained results. In addition, the interface contribution was demonstrated using the Lee and Park model. The relaxation time increased with the amount of added Joncryl. Hence, the coexistence of chain extension/branching chains coupled to the PLA-Joncryl-PBAT copolymer formation had to be taken into account to explain the improved mechanical properties.