Cyanobacterial metabolites as a source of sunscreens and moisturizers: a comparison with current synthetic compounds

The recognition of the harmful effects of ultraviolet radiation on the skin has led to the commercial development of inorganic and synthetic organic UV filters that can attenuate the negative effects of sunlight exposure. In addition, chemical moisturizers are extensively used in cosmetic products to improve the ability of skin to retain water. Whilst these chemicals have clear beneficial qualities, they may also have adverse effects such as contact sensitivity, oestrogenicity and even tumorigenic effects on human skin. Furthermore, the accumulation of such chemicals in the aquatic environment could be potentially harmful. Consequently, there is interest in exploiting safer alternatives derived from biological sources, especially from photosynthetic organisms such as cyanobacteria that have developed mechanisms for coping with high UV irradiation and desiccation. In order to overcome the detrimental effects of UV radiation, these microorganisms produce UV screening compounds such as mycosporine-like amino acids and scytonemin, which are good candidates as alternatives to current synthetic UV filters. In addition, extracellular substances produced by some extremophilic species living in hyper-arid habitats have a high water retention capacity and could be used in cosmetic products as moisturizers. In this review, we present an overview of the literature describing the potential of cyanobacterial metabolites as an alternative source for sunscreens and moisturizers

"Razne vijesti"

The present work shows the synthesis of nano-sized hybrid zeolitic imidazolate frameworks (ZIFs) with the rho topology based on a mixture of the linkers benzimidazole (bIm) and 4-methyl-5-imidazolecarboxaldehyde (4-m-5-ica). The hybrid ZIF was obtained by post-synthetic modification of ZIF-93 in a bIm solution. The use of different solvents, MeOH and N, N-dimethylacetamide (DMAc), and reaction times led to differences in the quantity of bIm incorporated to the framework, from 7.4 to 23 % according to solution-state NMR spectroscopy. XPS analysis showed that the mixture of linkers was also present at the surface of the particles. The inclusion of bIm to the ZIF-93 nanoparticles improved the thermal stability of the framework and also increased the hydrophobicity according to water adsorption results. N2 and CO2 adsorption experiments revealed that the hybrid material has an intermediate adsorption capacity, between those of ZIF-93 and ZIF-11. Finally, ZIF-93/11 hybrid materials were applied as fillers in polybenzimidazole (PBI) mixed matrix membranes (MMMs). These MMMs were used for H2/CO2 separation (at 180 °C) reaching values of 207 Barrer of H2 and a H2/CO2 selectivity of 7.7 that clearly surpassed the Robeson upper bound (corrected for this temperature)

Beyond the Womb and the Tomb: Identity, (Dis)embodiment and the Life Course

Grounded in the authors’ theoretical and ethnographic work on pregnancy and social life after death, this article explores the ways in which the body is involved in processes of identification. With a focus on the embodied nature of social identity, the article nonetheless problematizes a model of the life course that begins at the moments of birth and ends at death. Instead, it offers a more extended temporal perspective and examines other ways in which identity may be claimed, for example, via material objects and practices which evoke the body as imagined or remembered. By documenting pre-birth and post-mortem identity-making of this kind, it demonstrates how the unborn and the dead may come into social existence. In addition, a cultural privileging of both the body and visuality is shown to shore up the capacity of material objects and practices to shape social identities in a highly selective fashion. The article therefore proposes that models of the life course need to accommodate the meanings of pre-birth and post-mortem materialities and so incorporate a conceptualization of social identity as contested, relational and inevitably incomplete

Light flavor asymmetry of nucleon sea

The light flavor antiquark distributions of the nucleon sea are calculated in the effective chiral quark model and compared with experimental results. The contributions of the flavor-symmetric sea-quark distributions and the nuclear EMC effect are taken into account to obtain the ratio of Drell-Yan cross sections $\sigma^{\mathrm{pD}}/2\sigma^{\mathrm{pp}}$, which can match well with the results measured in the FermiLab E866/NuSea experiment. The calculated results also match the measured $\bar{d}(x)-\bar{u}(x)$ from different experiments, but unmatch the behavior of $\bar{d}(x)/\bar{u}(x)$ derived indirectly from the measurable quantity $\sigma^{\mathrm{pD}}/2\sigma^{\mathrm{pp}}$ by the FermiLab E866/NuSea Collaboration at large $x$. We suggest to measure again $\bar{d}(x)/\bar{u}(x)$ at large $x$ from precision experiments with careful experimental data treatment. We also propose an alternative procedure for experimental data treatment.Comment: 10 pages, 8 figures, final version to appear in EPJ

Combined Grand Canonical Monte Carlo and Molecular Dynamics approach based on a new Na+/CO2 forcefield : Investigation of CO2 adsorption in Faujasite systems

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New members of MOF-76 family containing Ho(III) and Tm(III) ions: Characterization, stability and gas adsorption properties

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Tailoring the separation properties of flexible metal-organic frameworks using mechanical pressure

International audienceMetal-organic frameworks are widely considered for the separation of chemical mixtures due to their adjustable physical and chemical properties. However, while much effort is currently devoted to developing new adsorbents for a given separation, an ideal scenario would involve a single adsorbent for multiple separations. Porous materials exhibiting framework flexibility offer unique opportunities to tune these properties since the pore size and shape can be controlled by the application of external stimuli. Here, we establish a proof-of-concept for the molecular sieving separation of species with similar sizes (CO2/N2 and CO2/CH4), via precise mechanical control of the pore size aperture in a flexible metal-organic framework. Besides its infinite selectivity for the considered gas mixtures, this material shows excellent regeneration capability when releasing the external mechanical constraint. This strategy, combining an external stimulus applied to a structurally compliant adsorbent, offers a promising avenue for addressing some of the most challenging gas separations. © 2020, The Author(s)

Direct accessibility of mixed-metal (III/II) acid sites through the rational synthesis of porous metal carboxylates

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