All-polymeric transient neural probe for prolonged in-vivo electrophysiological recordings

Transient bioelectronics has grown fast, opening possibilities never thought before. In medicine, transient implantable devices are interesting because they could eliminate the risks related to surgical retrieval and reduce the chronic foreign body reaction. However, despite recent progress in this area, the short functional lifetime of devices due to short-lived transient metals, which is typically a few days or weeks, still limits the potential of transient medical devices. We report that a switch from transient metals to an entirely polymer-based approach allows for a slower degradation process and a longer lifetime of the transient probe, thus opening new possibilities for transient medical devices. As a proof-of-concept, we fabricated all-polymeric transient neural probes that can monitor brain activity in mice for a few months rather than a few days or weeks. Also, we extensively evaluated the foreign body reaction around the implant during the probe’s degradation. This kind of devices might pave the way for several applications in neuroprosthetics.

Energy spectrum and density of states in 3d-transient metals and alloys

In this paper, the formation of the magnetic moment, the energy spectrum and the density of States of d -electrons in transition metals are considered in the framework of a two-zone s - d model based on a generalized crystalline Hamiltonian. It is shown that taking into account the multiplicity of the degeneration of s - d electrons in the Hamiltonian leads to an additional exchange-correlation interaction ( U - K ), which together with the correlation interaction determines the electronic structure of d -metals. In this case, there is a three-peak density of States, which turns into a two-peak, if we exclude the exchange-correlation interaction.

Properties of selected materials with non-stoichiometric compounds used for wear-resistant coatings

The article analyzes the influence of fill ratio of interstitial positions by nitrogen or carbon on technological and functional properties of transient metals of groups from IVb to VIb. In addition to literature data, the results of own comparative studies on the durability of cutting edges coated with transition metal nitrides with stoichiometric and non-stoichiometric composition are presented.

Anaerobic and aerobic beer aging

Yellow, orange, red and brown pigments are formed by air oxidation of single polyphenols or by thermal degradation of sugars to caramels. Caramels increase their colours during anaerobic heating or decrease them by air oxidation. Epicatechin and caramel undergo reversible redox reaction followed by degradation and/or polymerisation at beer aging. That is why both of these colour compounds, besides acting as acid/alkali indicators, can also represent redox indicators that gradually become irreversible. These reactions are accelerated by transient metals or buffering solutions and are therefore more distinct in tap or brewing water than in deionised water. The kind of the brewing water then predetermines not only the beer attributes but also the course of beer aging. Coloured pigments can be partially bleached by reducting agents such as yeast oxidoreductase enzymes and the colour can be then recovered by oxidation; this depends on their polymerisation degree. Methylene blue and methyl red can be used as artificial oxidation-reduction indicators for the study of the redox potential changes because they act reversibly or irreversibly under aerobic or anaerobic conditions, respectively.

Study on the Interaction of Ions of Transient Metals with Ascorbic Acid in the Presence of Different Scavengers of Active Oxygen Species in SOS Chromotes

SOS chromotest was employed to study the interaction of ascorbic acid with free ions of transient metals in the presence of added catalase, superoxide dismutase or D-mannitol. Catalase diminished the genotoxic activity of the mixture of ascorbic acid with copper ions in E. coli strains PQ37 and PQ 300, but genotoxicity of this mixture was not suppressed by superoxide dismutase and D-mannitol. The results suggest that copper ions diminished the content of peroxide generated by ascorbic acid.