Transformation of polarons to bipolarons in disordered matter

The polaron to bipolaron transition in disordered media under the influence of a broadband ac electric field is suggested: ac conductivity vs. frequency measurements in disordered media with inhomogeneous disorder induce spatio-temporal fluctuations of the density of polarons yielding polaron to bipolaron transformation. The external field results in the transition, alternatively to an increasing doping level. The assertion is confirmed by performing successive complex impedance measurements in disordered media. A systematic increase of the real part of the ac conductivity in the frequency domain, followed by mutual reduction of the magnetic inductivity of conducting polypyrrole, are explained.Comment: 8 pages plus 3 figures. Accepted for publication in Applied Physics Letter

Fabrication of Metasurfaces on Building Construction Materials for Potential Electromagnetic Applications in the Microwave Band

Energy self sufficiency, as well as optimal management of power in buildings is gaining importance, while obtaining power from traditional fossil energy sources is becoming more and more expensive. In this context, millimeter scale metasurfaces can be employed to harvest energy from microwave sources. They can also be used as sensors in the microwave regime for efficient power management solutions. In the current study, a simple spray printing method is proposed to develop metasurfaces in construction materials, i.e., plasterboard and wood. Such materials are used in the interior design of buildings; therefore, the implementation of metasurfaces in large areas, such as walls, doors and floors, is realized. The fabricated metasurfaces were characterized regarding their electromagnetic performance. It is hereby shown that the investigated metasurfaces exhibit an efficient electromagnetic response in the frequency range 4 to 7 GHz, depending on the MS. Thus, spray printed metasurfaces integrated on construction materials can potentially be used for electromagnetic applications, for buildings power self efficiency and management.Comment: 14pages, 8 figure

Effect of composition on the dielectric relaxation of zeolite-conducting polyaniline blends

The complex permittivity of conducting polyaniline and zeolite - polyaniline blends was measured in the frequency range 0.01 to 2000000 Hz from room temperature to liquid nitrogen temperature. A loss peak is detected for 25, 35 and 50 wt % zeolite blends. Its position in the frequency domain, activation energy and intensity is a function of composition. The experimental results are interpreted through the competing multiple role of zeolite: as being less conducting than polyaniline, it impedes the electric charge flow by dividing large conducting polyaniline regions into smaller pieces, subsequently provides short-range pathways and, moreover, enriches the blend in interfaces separating zeolite from polyaniline.Comment: Accepted for publication in J. Appl. Phy

SGLT2 αναστολείς και νεφροπροστασία

Ένας στους δύο ασθενείς με σακχαρώδη διαβήτη τύπου ΙΙ (ΣΔ) παρουσιάζει χρόνια νεφρική νόσο (XNN) και κάποιοι από αυτούς θα οδηγηθούν σε χρόνια νεφρική νόσο τελικού σταδίου, ενώ παράλληλα παρουσιάζουν υψηλό καρδιαγγειακό κίνδυνο. Ακόμη και με την ευρεία χρήση των αναστολέων του συστήματος ρενίνης-αγγειοτενσίνης-αλδοστερόνης ο κίνδυνος για νεφρική εξέλιξη υπάρχει. Ο συμμεταφορέας νατρίου-γλυκόζης (SGLT2) στο νεφρό προκαλεί δυναμική επαναρρόφηση της διηθούμενης γλυκόζης μαζί με το νάτριο. Οι αναστολείς αυτών των υποδοχέων (SGLT2i) αρχικά σχεδιάστηκαν και αναπτύχθηκαν ως φάρμακα για αντιδιαβητική χρήση, με σκοπό τη μείωση της υπεργλυκαιμίας. Απρόσμενα κατέγραψαν μία στατιστικά σημαντική μείωση στον κίνδυνο θανάτου, καρδιαγγειακών συμβάντων και εξέλιξης της ΧΝΝ. Ο ρόλος των SGLT2i να μειώνουν την καρδιαγγειακή θνητότητα και να βελτιώνουν τη διατήρηση του ρυθμού σπειραματικής διήθησης έχει αποδειχτεί από αρκετές τυχαιοποιημένες μελέτες. Οι νεφρικές τους δράσεις φαίνονται να είναι πλειοτροπικές επηρεάζοντας άμεσα και έμμεσα το νεφρό. H αναστολή των SGLT2 καθίσταται πλέον απαραίτητη στη θεραπεία της διαβητικής νεφροπάθειας. Ακόμη πιο πρόσφατα, η ωφέλιμη νεφρική δράση τους επεκτείνεται και σε ασθενείς χωρίς ΣΔ. Στην παρούσα βιβλιογραφική ανασκόπηση αναλύονται οι μηχανισμοί με τους οποίους οι SGLT2i προάγουν τα νεφρικά οφέλη, όπως επίσης καταγράφονται και τα νεφρικά αποτελέσματα από τις κυριότερες τυχαιοποιημένες μελέτες σε πληθυσμό με ή χωρίς ΣΔ.One out of two patients with type 2 diabetes develop a certain degree of renal impairment and in many of them chronic kidney disease progresses to end-stage renal disease with increased risk of cardiovascular mortality. Although, renin-angiotensin system blockers are usually be used, a substantial residual risk of renal progression remains. The SGLT2 protein reabsorbs glucose and sodium in the kidney. The inhibitors of SGLT2 were firstly designed and developed for their hypoglycemic effect, but surprisingly reported a statistical significant reduction of overall mortality, cardiovascular risk and renal progression. The role of SGLT2i in the reduction of cardiovascular mortality and the preservation of the estimated glomerular filtration rate has been reported in many randomized controlled trials. The renal effects are pleiotropic and consist of direct and indirect effects. The SGLT2i have become important treatment target for the diabetic nephropathy. Recently, the beneficial role of SGLT2 have expanded in patients without diabetes. This review outlines the mechanisms, whereby the SGLT2s promote the renal effects, as well as the renal outcomes from the most important randomized trials in patients with or without diabetes