TOWARD A MORE EFFICIENT UTILISATION OF BETALAINS AS PIGMENTS FOR DYE-SENSITIZED SOLAR CELLS

We report on the use of natural dyes, betalains, as pigments for Dye-Sensitized Solar Cells (DSSC). Time-Dependent Density Functional Theory calculations provide the electronic spectra of the various types of betalain dyes and allow a discussion of their matching to the solar spectrum. Experimentally, we vary parameters such as the nature of the extracting solvent, the pH and the composition of the extract, to optimize the fabrication of DSSCs using betalains. Based on UV-Vis spectra correlated with electro-optic measurements providing the photovolatic conversion efficiency under standard AM1.5 conditions we find that the decrease of the pH of the dye solution leads to an increase of the DSSC performance, likely due to the increasing ratios of betacyanins with respect to betaxanthins in the extracts as well as the possible hydrolysis of betanin to betanidin. In order to fabricate better DSSCs using betalain natural dyes, we propose to use water as extracting solvent, to increase the content in betacyanins on the photoanode by a preliminary purification and to raise the stability of the dyes preferably by using anti-oxidizing copigments that do not interact with the substrate

Human colon adenocarcinoma HT-29 cell: electrochemistry and nicotine stimulation

Recently, it was demonstrated that colorectal cancer HT-29 cells can secrete epinephrine (adrenaline) in an autocrine manner to auto-stimulate cellular growth by adrenoreceptors activation, and that this secretion is enhanced by nicotine, showing an indirect relation between colorectal cancer and tobacco. The electrochemical behaviour of human colon adenocarcinoma HT-29 cells from a colorectal adenocarcinoma cell line, the hormone and neurotransmitter epinephrine, and nicotine, were investigated by cyclic voltammetry, using indium tin oxide (ITO), glassy carbon (GC) and screen printed carbon (SPC) electrodes. The oxidation of the HT-29 cells, previously grown onto ITO or SPC surfaces, followed an irreversible oxidation process that involved the formation of a main oxidation product that undergoes irreversible reduction, as in the epinephrine oxidation mechanism. The effect of nicotine stimulation of the HT-29 cells was also investigated. Nicotine, at different concentration levels 1, 2 and 15 mM, was introduced in the culture medium and an increase with incubation time, 0 to 3 h and 30 min, of the HT-29 cells oxidation and reduction peaks was observed. The interaction of nicotine with the HT-29 cells stimulated the epinephrine secretion causing an increase in epinephrine release concentration, and enabling the conclusion that epinephrine and nicotine play an important role in the colorectal tumour growth

The effect of Mg location on Co-Mg-Ru/gamma-Al2O3 Fischer-Tropsch catalysts

The effectiveness of Mg as a promoter of Co-Ru/γ-Al(2)O(3) Fischer–Tropsch catalysts depends on how and when the Mg is added. When the Mg is impregnated into the support before the Co and Ru addition, some Mg is incorporated into the support in the form of Mg(x)Al(2)O(3+x) if the material is calcined at 550°C or 800°C after the impregnation, while the remainder is present as amorphous MgO/MgCO(3) phases. After subsequent Co-Ru impregnation Mg(x)Co(3−x)O(4) is formed which decomposes on reduction, leading to Co(0) particles intimately mixed with Mg, as shown by high-resolution transmission electron microscopy. The process of impregnating Co into an Mg-modified support results in dissolution of the amorphous Mg, and it is this Mg which is then incorporated into Mg(x)Co(3−x)O(4). Acid washing or higher temperature calcination after Mg impregnation can remove most of this amorphous Mg, resulting in lower values of x in Mg(x)Co(3−x)O(4). Catalytic testing of these materials reveals that Mg incorporation into the Co oxide phase is severely detrimental to the site-time yield, while Mg incorporation into the support may provide some enhancement of activity at high temperature

Terapia transcateter a valvei aortice

Institutul de Boli Cardiovasculare „Prof. Dr. George I.M. Georgescu”, Universitatea de Medicină și Farmacie „Grigore T. Popa” Iași, Al XIII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” și al III-lea Congres al Societății de Endoscopie, Chirurgie miniminvazivă și Ultrasonografie ”V.M.Guțu” din Republica MoldovaImplantarea de valvă aortică transcateter (TAVI) a revoluționat managementul terapeutic al stenozei aortice severe oferind o șansă la o viață de bună calitate inclusiv pacienților fragili, cu numeroase comorbidități și contraindicații pentru intervenția chirurgicală convențională. Ultimele ediții ale ghidurilor societăților americane și europene de cardiologie privind managementul afecțiunilor valvulare, au inclus TAVI în rândul indicațiilor terapeutice rezervate unui grup aparte de pacienți, respectiv cei considerați inoperabili sau a prezenta un risc ridicat pentru intervenția convențională (protezare valvulară chirurgicală) în urma evaluării multidisciplinare de către „Echipa Inimii”. La Institutul de Boli Cardiovasculare „Prof. Dr. George I.M. Georgescu” din Iași au fost efectuate 66 de intervenții TAVI în intervalul 2015-2019 cu un prognostic post-procedural favorabil și o rată redusă a complicațiilor semnificative (2 cazuri) și mortalității (1 caz). Astfel, TAVI a deschis un nou capitol în tratamentul stenozei aortice severe cu o reducere semnificativă a riscului de morbiditate și mortalitate comparativ cu tratamentul chirurgical convențional sau cel medical. Scopul studiului de față este de a analiza, prin prisma experienței personale și a studiilor publicate în literatura de specialitate în ultimii 10 ani, indicațiile TAVI, evaluare preprocedurală, selecția pacienților, tipului și dimensiunii protezei, echipamentul necesar, etapele intervenției, prognosticul și complicațiile periprocedurale potențiale alături de managementul lor. O atenție deosebită este acordată prevenției complicațiilor precoce și tardive care condiționează succesul intervenției și calitatea vieții pacienților. Acumularea progresivă de experiență și ameliorarea continuă a protezelor și dispozitivelor de implantare conduce la o creștere a duratei de viață a valvei implantate, reducerea ratei complicațiilor, creșterea speranței de viață și a gradului de safisfacție a pacienților

Novel cobalt zinc oxide Fischer-Tropsch catalysts synthesised using supercritical anti-solvent precipitation

Cobalt zinc oxide catalysts have been prepared by anti-solvent precipitation in supercritical CO2 and investigated for CO hydrogenation. Here we show how the textural and catalytic properties of the catalyst can be tailored by the addition of water to the initial solution of cobalt and zinc acetates in methanol. Characterization of the catalysts by powder X-ray diffraction, infra-red and Raman spectroscopy showed that in the absence of water a high surface area mixed acetate was produced which upon calcination formed wurtzite type Zn1−xCoxO and spinel type ZnxCo3−xO4. The addition of 5 vol.% water resulted in a phase separated Co3O4/ZnO catalyst and enhanced active cobalt surface area as a result of disruption of the solvent/CO2 phase equilibrium during precipitation

High activity redox catalysts synthesized by chemical vapor impregnation

The use of precious metals in heterogeneous catalysis relies on the preparation of small nanoparticles that are stable under reaction conditions. To date, most conventional routes used to prepare noble metal nanoparticles have drawbacks related to surface contamination, particle agglomeration, and reproducibility restraints. We have prepared titania-supported palladium (Pd) and platinum (Pt) catalysts using a simplified vapor deposition technique termed chemical vapor impregnation (CVI) that can be performed in any standard chemical laboratory. These materials, composed of nanoparticles typically below 3 nm in size, show remarkable activity under mild conditions for oxidation and hydrogenation reactions of industrial importance. We demonstrate the preparation of bimetallic Pd–Pt homogeneous alloy nanoparticles by this new CVI method, which show synergistic effects in toluene oxidation. The versatility of our CVI methodology to be able to tailor the composition and morphology of supported nanoparticles in an easily accessible and scalable manner is further demonstrated by the synthesis of Pdshell–Aucore nanoparticles using CVI deposition of Pd onto preformed Au nanoparticles supported on titania (prepared by sol immobilization) in addition to the presence of monometallic Au and Pd nanoparticles