Activity

Supramolecular mechanofluorophores based on charge-transfer (CT) interactions between fluorescent pyrene and naphthalene diimide(s) with a tandem structure are newly developed and incorporated into the mid-chain of poly(ε-caprolactone)s. The fluorescence (FL) is quenched by the intramolecular CT interactions even at low concentrations both in solution and in the polymer matrix, and turn-on FL is induced upon application of mechanical forces.One of the challenges when using lithium metal as the anode in rechargeable lithium batteries is the formation and growth of lithium dendrites. The recent observation by He et al. (Nat. Nanotechnol., 2019, 14, 1042-1047) and Zhang et al. (Nat. Nanotechnol., 2020, 15, 94-98) confirm the presence of the root-growth mode for the growth of lithium dendrites (whiskers, spheres and hillocks). In this work, we introduced a non-Newtonian flow model to describe the flow of lithium in lithium metal and incorporate the contributions of viscous dissipation, surface energy, kinetic energy and strain energy in the analysis of the stress relaxation and the growth of a Li-sphere and a Li-whisker. Nonlinear second-order differential equations are derived for the growth of the Li-sphere and the Li-whisker. Closed-form solutions for the temporal evolution of the Li-sphere and the Li-whisker are obtained under the conditions such that the contributions of the surface energy, kinetic energy and strain energy stored in the cantilever beam to the stress relaxation in the lithium metal are negligible. Using the Lippmann relation in specific surface energy, we demonstrated that increasing the electric potential reduces the resistance to the flow of lithium into the Li-sphere and the Li-whisker. The results reveal the need to suppress the cycling-induced strain energy (misfit strain and biaxial modulus) in order to mitigate the growth of Li dendrites (whiskers, spheres and hillocks).Catechinic acid (CA), widely present in tea and fruits, has vital biological and pharmacological properties. CA plays an important role in the regulation of lifespan. However, the mechanism behind its anti-aging properties remains poorly characterized. In the present study, Caenorhabditis elegans (C. elegans) was used as a model organism. It was found that CA induced mitophagy which prevented the accumulation of dysfunctional mitochondria with age and profoundly extended lifespan. Notably, CA significantly improved the fitness of aging worms, particularly the treatment slowed age-related decline in observed spontaneous movements. Furthermore, CA was found to eliminate dysfunctional mitochondria in the gut and muscle cells, and demonstrated that the lifespan-prolonging effects of CA can be attributed to mitophagy along with the likely regulation of the genes bec-1 and pink-1. The results of this study indicated that pharmacologically induced mitophagy has a profound impact on aging, providing a novel therapeutic intervention against aging and age-related diseases.Transition-metal-catalyzed carbene transfer reactions, involving diazo compounds and their precursors, are powerful tools for creating new C-C bonds. Depending on the involved catalytic system, the carbene insertion can efficiently be driven towards a specific functional group for the synthesis of a wide portfolio of fine chemicals. The present report is focused on the catalytic activity of iron catalysts in promoting alkene cyclopropanations, C-H and X-H (X = N, O, S, Se, Si, Sn, Ge) functionalizations. Porphyrin, porphyrinoid and non-heme iron complexes are discussed by analyzing experimental studies and theoretical calculations performed for proposing reaction mechanisms. The catalytic activity of artificial iron biocatalysts is also briefly reported in order to underline the similarities and differences between reaction mechanisms mediated by modified biocatalysts and synthetic catalysts. This review summarizes the achievements made in this field since 2006.The abnormal concentrations of both biothiols and pH in lysosomes are seriously related to many major diseases, such as Parkinson’s and Alzheimer’s diseases. Up to now, there are few reports that clearly illustrate the relationship between lysosomal pH and biothiols via fluorescence assay. Herein, novel carbon dots (Scy-CDs) are prepared with good water dispersibility and excellent photostability, and a large Stokes shift of 106 nm is exhibited under an excitation wavelength of 450 nm. The remarkable pH-dependent behavior of Scy-CDs is presented with the fluorescence quenching based on the donor-excited photoinduced electron transfer (d-PET) process. The pKa value is 5.30, which is in good agreement with the range of the normal and abnormal lysosomal pH. Upon the addition of cysteine (Cys) or homocysteine (Hcy), the d-PET process is effectively inhibited with fluorescence recovery totally. The significant co-localization of Scy-CDs with Lyso-Tracker Deep Red in HEp-2 cells and the Pearson correlation coefficient 0.88 strongly suggest that the Scy-CDs can target lysosomal pH and Cys/Hcy in living cells.We study the two-dimensional assemblies of interacting colloidal particles in a loosely focussed optical trap. ThiametG As the optical confinement is increased, the system becomes ordered and we investigate how these crystallites maintain their order under externally imposed oscillation. For small amplitudes, the crystalline order remains intact and the system behaves like a rigid body as predicted by numerical simulations. However, the rigidity breaks at large amplitudes, which we infer to be caused by the anharmonic component of the confinement potential. These studies are general enough to be applied to other physical systems comprising ordered finite-sized assemblies under external dynamic perturbation.This study presents the first local measurements of metals in snow from the Argentine Central Andes. Cu, Pb and Zn were selected as specific tracers of anthropogenic local emission sources in the study area. Snow samples were collected during winter (2014, 2015 and 2016) at two sites with different characteristics Punta de Vacas and Vallecitos. The samples were analyzed by ICP-MS, and the average concentrations found were 1.4 μg L-1 (Cu), 2.2 μg L-1 (Pb) and 14.2 μg L-1 (Zn) in the snow samples from Vallecitos, and 5.3 μg L-1 (Cu), 2.6 μg L-1 (Pb) and 24.0 μg L-1 (Zn) in the snow samples from Punta de Vacas. These data and the snowfall amount in each sampling site were statistically analyzed. Results suggested that the levels of metals in the snow are influenced not only by the atmospheric concentrations, but also by the amount of precipitated snow. Additionally, an atmospheric dispersion model, CALPUFF, was applied in the study area to determine the origin of the studied metals and to understand the spatial distribution pattern of the concentrations found.