Extraction Behaviors of Heavy Rare Earths with Organophosphoric Extractants: The Contribution of Extractant Dimer Dissociation, Acid Ionization, and Complexation. A Quantum Chemistry Study.

Heavy rare earths (HREs), namely Ho3+, Er3+, Tm3+, Yb3+ and Lu3+, are rarer and more exceptional than light rare earths, due to the stronger extraction capacity for 100 000 extractions. Therefore, their incomplete stripping and high acidity of stripping become problems for HRE separation by organophosphoric extractants. However, the theories of extractant structure-performance relationship and molecular design method of novel HRE extractants are still not perfect. Beyond the coordination chemistry of the HRE-extracted complex, the extractant dimer dissociation, acid ionization, and complexation behaviors can be crucial to HRE extraction and reactivity of ionic species for understanding and further improving the extraction performance. To address the above issues, three primary fundamental processes, including extractant dimer dissociation, acid ionization, and HRE complexation, were identified and investigated systematically. The intrinsic extraction performances of HRE cations with four acidic organophosphoric extractants (P507, P204, P227 and Cyanex 272) were studied by using relativistic energy-consistent 4f core pseudopotentials, combined with density functional theory and a solvation model. Four acidic organophosphoric extractants have been qualified quantitatively from microscopic structures to chemical properties. It has been found that the Gibbs free energy changes of the overall extraction process (sequence: P204 > P227 > P507 > Cyanex 272) and their differences as a function of HREs (sequence: Ho/Er > Er/Tm > Tm/Yb > Yb/Lu) are in good agreement with the experimental maximum extraction capacities and separation factors. These results could provide an important approach to evaluate HRE extractants by the comprehensive consideration of dimer dissociation, acid ionization, and complexation processes. This paper also demonstrates the importance of the P-O bond, the P-C bond, isomer substituent, and solvation effects on the structure-performance relationship that can be used to guide molecular designs of HRE extraction in future.

Skin Ageing: A Progressive, Multi-Factorial Condition Demanding an Integrated, Multilayer-Targeted Remedy.

Of the human organs, skin is the most visible one that displays the manifestations of ageing. It has a very intricate microanatomical structure and performs several key physiological functions. The pathophysiology of cutaneous ageing is characterized by deterioration of structural stability and functional integrity, implying a continuous reduction in maximal function and reserve capacity, as a result of the accumulating damage due to both intrinsic and extrinsic factors. Elimination of unfavorable expressions associated with facial and cutaneous ageing is the key patient demand in aesthetic dermatology. Even though the progress has been made in nonsurgical therapies like fillers and lasers, non-invasive interventions by using skin care products designed for rejuvenation at an early stage are the most popular and accessible solution among people. In this review, we have scrutinized the ageing-associated cutaneous changes at molecular, cellular and tissue levels. To optimize the ageing process towards a healthy skin, we propose an integrated, multilayer-targeted intervention, which involves both topical application of anti-ageing formulations from outside and oral supplementation from inside. Additionally, several promising naturally derived ingredients are reviewed from an anti-aging perspective. Most of them possess various bioactivities and may contribute to the development of the mentioned anti-ageing remedy.

An artificially designed elastin-like recombinant polypeptide improves aging skin.

BACKGROUND: As a substrate for cell growth, elastin can promote the regeneration and remodeling of the epidermis, which plays an important role in delaying skin aging. However, elastin proteins are more than 700 amino acids long and cannot be absorbed through the skin, which prevents the direct utilization of elastin in the prevention and treatment of aging skin. METHODS: We designed an elastin-like recombinant polypeptide (ELR) which could be absorbed through the skin based on the property of hexapeptide VGVAPG. Thirty healthy Chinese Han female participants which met the criteria were enrolled in this study and all of them completed the tests including elasticity, tightness, and wrinkle detection. The participants used this polypeptide for 4 weeks and were tested in three visits: one day before trial started (D0), and 14 and 28 days after the trial (D14 and D28, respectively). Paired t-tests or Wilcoxon signed-rank tests for non-parametric measures were used to determine the difference between D0 and D14, or D0 and D28. RESULTS: The skin elasticity level in the thirty participants was significantly increased after using ELR for 28 days (P=0.024), and the average value of skin firmness (Uf) declined from 3.313 (D0) to 3.292 (D14) and 3.265 (D28), although there was no statistically significant difference between treatment and pre-treatment. Furthermore, the wrinkle count (D14: P<0.001; D28: P<0.001), wrinkles volume (D14: P<0.001; D28: P=0.008), and wrinkles area (D14: P<0.001; D28: P<0.001) of Crow's feet were significantly improved by using ELR for 14 days or 28 days. CONCLUSION: Continuous use of ELR could significantly improve skin elasticity and reduce wrinkles.