Ionfolyadékok katalitikus és elektrokémiai alkalmazása = Catalytic and electrochemical application of ionic liquids

A pályázat keretében egy elméleti és gyakorlati szempontból egyaránt az érdeklődés homlokterében álló területtel, ionfolyadékok széleskörű vizsgálatával foglalkoztunk. Kutatásaink kiterjedtek új típusú ionfolyadékok szintézisére, szerkezetének vizsgálatára, elektrokémiai és katalitikus alkalmazására. Legfontosabb eredményeknek a következőket tartjuk. Imidazolium alapú ionfolyadékok szerkezetének pontosabb megállapítása céljából a kation-anion pár koordinációt tanulmányoztuk kvantumkémiai módszerekkel. Megállapítottuk, hogy az imidazolium kation alapú ionfolyadékok kristályos polimorfizmusa közvetlen összefüggésben van a kation-anion koordináció esetében kimutatott konformerek szerkezetével. Különböző redoxi-rendszerekben vizsgált anyagok (elsősorban ferrocén-származékok) elektrokémiai vizsgálata során megállapítottuk, hogy az általunk vizsgált ionfolyadékok széles potenciál-ablakukkal, nagy elektromos vezetésükkel voltammetriás mérésekhez ideálisan alkalmazható alap-elektrolitok. Számos Pt(difoszfin)Cl2 típusú komplex elemi reakcióit vizsgáltuk ionfolyadékokban 31P NMR segítségével. A platina-, valamint az analóg palládium-komplexeket karbonilezési és kapcsolási reakciókban alkalmaztuk. Farmakológiai szempontból jelentős vegyületek (elsősorban szteroidok) szintézisét valósítottuk meg mind hagyományos oldószerekben, mind ionfolyadékokban. | Within the framework of this project the investigation of a field of both high theoretical and practical importance, namely, the wide-ranging research of ionic liquids has been carried out. The synthesis and structural investigation of novel ionic liquids, as well as their application in electrochemistry and catalysis were comprised in our research project. The most important results are considered as follows. In order to get a deeper insight into the structure of imidazolium-based ionic liquids, the cation-anion coordination was studied by quantum-chemical methods. The polymorphism of these systems is closely related to the structure of conformers observed in cation-anion coordination. During the electrochemical investigation of redox-active compounds (primarily ferrocene derivatives) the ionic liquids with wide potential-window and large conductivity proved to be highly suitable media (base-electrolites) for voltammetric measurements. The elementary reactions of several Pt(diphosphine)Cl2 type complexes have been investigated in ionic liquids by 31P NMR. The platinum complexes and their palladium analogues have been used in carbonylation and cross-coupling reactions. The synthesis of compounds of pharmacological importance (steroids, tropanes, ferrocenes) have been accomplished both in ionic liquids and conventional organic solvents

Iron uptake from manufactured nanomaterials: obscured mechanism, controversial effect

Transition metals in nanomaterials such as iron, manganese or zinc are essential microelements for plants. When these metals are present in suboptimal concentration for the plants, deficiency syndromes develop that causes reduced crop production or poor fruit quality. Low mineral content of plant products has a major role in human malnutrition. Most stable Fe-chelates for the correction of Fe deficiency are not biodegradable and expensive so applying manufactured nanomaterials may serve as a cheap and eco-friendly alternative. Newly designed, transition metal containing nanomaterials stabilized in colloid suspension have been characterised and then applied in hydroponic cultures to cucumber model plants in a wide range of concentration. The uptake and distribution of the elements from the nanomaterials and their utilization were investigated by microXRF mapping, ICP-MS, enzyme activity tests, gene expression measurements and the changes in some basic physiological parameters were followed. Nanoferrihydrite and nano-Mn-Zn-ferrite colloid suspensions with 3-8 nm particle size applied in 0.01-0.02 mM concentration and at slightly acidic pH proved to be a good source of Fe, Mn and Zn in various experimental conditions. Mn-Zn-ferrite has also been tested at pH 7.5 and Fe deficient cucumber plants showed a significant recovery after 3 days of application in terms of chlorophyll concentration and photosynthetic efficiency but not at pH 8.5. Mn and Zn deficient plants also showed recovery upon addition of the ferrite. Ferric chelate reductase assays showed that it is not the normal reduction-based uptake pathway that plays a role in the iron utilization of these nanoparticles. Analysis of root ferric chelate reductase expression pointed out a quick utilisation of Fe content of the nanoferrihydrite particles. Elevated concentrations of the nanoferrite at the millimolar range as compared to equal concentrations of micronutrient salts proved to be significantly less toxic. However, another nanomaterial, an insoluble nano FeCo powder applied to the nutrient solution of cucumber in high concentration causes severe chlorosis due to cobalt toxicity, pointing on that the composition of the nanoparticles is highly important for their bioactivity. Keywords: nanomaterial, ferrite, ferrihydrite, fertilizer, ferric chelate reductase, toxicity This work was supported by the National Research, Development and Innovation Office, Hungary (NKFIH) K115784, 115913, 124159 and VEKOP-2.3.3-15-2016-00008. Á. Solti was also supported by the Bolyai János Research Scholarship of the Hungarian Academy of Sciences (BO/00207/15/4)

Liposome-mediated gene transfer in fish embryos

Liposome-mediated gene transfer was used to introduce large DNA constructs into zygotes of African catfish. The technique is based on the delivery of recombinant bacteriophage lambda particles (or DNA-protamine complexes) into the cytoplasm of target cells by negatively charged, large unilamellar liposomes. Dechorionated zygotes and early fish embryos were treated with the transforming liposomes. Expression of the introduced reporter genes during the first three weeks of the development of the larvae was followed by measuring the activity of corresponding enzymes. These assays have indicated very efficient DNA uptake into the embryos.</p

Liposome-mediated gene transfer in fish embryos

Liposome-mediated gene transfer was used to introduce large DNA constructs into zygotes of African catfish. The technique is based on the delivery of recombinant bacteriophage lambda particles (or DNA-protamine complexes) into the cytoplasm of target cells by negatively charged, large unilamellar liposomes. Dechorionated zygotes and early fish embryos were treated with the transforming liposomes. Expression of the introduced reporter genes during the first three weeks of the development of the larvae was followed by measuring the activity of corresponding enzymes. These assays have indicated very efficient DNA uptake into the embryos.</p

Coupled diffusion/adsorption model for response of precipitate-based iodide-selective electrodes to primary-ion activity steps

Switched wall-jet streams of Iodide solutions Impinging on Agl-based Ion-selective electrodes (ISEs) give potential responses after the first 20 ms. The responses to Iodide activity steps of constant ratio a (flnal)/a (Initial) are highly dependent on the starting activity. This Is contrary to most present theories of ISE response, particularly those describing reversible surface Ion exchange controlled by diffusion to a surface or first-order reaction kinetics. Experimentally, diffusion Is Involved over all concentration ranges but Is coupled with some surface adsorption Isotherm. At low activities, steps up or down are slower than diffusion because of the need to form or remove some of the adsorbed layer. At high activities, step responses approach pure diffusion control, since adsorption Is nearly saturated. Dependence on the starting activity requires a nonlinear adsorption Isotherm, which Is consistent with adsorption data showing logarithmic dependence of surface Ion concentration on bathing activity. Experimentally, rate-controlling dlssolutlon/preclpltatlon processes are not likely. © 1991, American Chemical Society. All rights reserved

Development of Various Photovoltaic‐Driven Water Electrolysis Technologies for Green Solar Hydrogen Generation

Direct solar hydrogen generation via a combination of photovoltaics (PV) and water electrolysis can potentially ensure a sustainable energy supply while minimizing greenhouse emissions. The PECSYS project aims at demonstrating a solar-driven electrochemical hydrogen generation system with an area >10 m2 with high efficiency and at reasonable cost. Thermally integrated PV electrolyzers (ECs) using thin-film silicon, undoped, and silver-doped Cu(In,Ga)Se2 and silicon heterojunction PV combined with alkaline electrolysis to form one unit are developed on a prototype level with solar collection areas in the range from 64 to 2600 cm2 with the solar-to-hydrogen (StH) efficiency ranging from ≈4 to 13%. Electrical direct coupling of PV modules to a proton exchange membrane EC to test the effects of bifaciality (730 cm2 solar collection area) and to study the long-term operation under outdoor conditions (10 m2 collection area) is also investigated. In both cases, StH efficiencies exceeding 10% can be maintained over the test periods used. All the StH efficiencies reported are based on measured gas outflow using mass flow meters

The resilience framework as a strategy to combat stress-related disorders

status: publishe

Candida bloodstream infections in intensive care units: analysis of the extended prevalence of infection in intensive care unit study

Item does not contain fulltextOBJECTIVES: To provide a global, up-to-date picture of the prevalence, treatment, and outcomes of Candida bloodstream infections in intensive care unit patients and compare Candida with bacterial bloodstream infection. DESIGN: A retrospective analysis of the Extended Prevalence of Infection in the ICU Study (EPIC II). Demographic, physiological, infection-related and therapeutic data were collected. Patients were grouped as having Candida, Gram-positive, Gram-negative, and combined Candida/bacterial bloodstream infection. Outcome data were assessed at intensive care unit and hospital discharge. SETTING: EPIC II included 1265 intensive care units in 76 countries. PATIENTS: Patients in participating intensive care units on study day. INTERVENTIONS: None. MEASUREMENT AND MAIN RESULTS: Of the 14,414 patients in EPIC II, 99 patients had Candida bloodstream infections for a prevalence of 6.9 per 1000 patients. Sixty-one patients had candidemia alone and 38 patients had combined bloodstream infections. Candida albicans (n = 70) was the predominant species. Primary therapy included monotherapy with fluconazole (n = 39), caspofungin (n = 16), and a polyene-based product (n = 12). Combination therapy was infrequently used (n = 10). Compared with patients with Gram-positive (n = 420) and Gram-negative (n = 264) bloodstream infections, patients with candidemia were more likely to have solid tumors (p < .05) and appeared to have been in an intensive care unit longer (14 days [range, 5-25 days], 8 days [range, 3-20 days], and 10 days [range, 2-23 days], respectively), but this difference was not statistically significant. Severity of illness and organ dysfunction scores were similar between groups. Patients with Candida bloodstream infections, compared with patients with Gram-positive and Gram-negative bloodstream infections, had the greatest crude intensive care unit mortality rates (42.6%, 25.3%, and 29.1%, respectively) and longer intensive care unit lengths of stay (median [interquartile range]) (33 days [18-44], 20 days [9-43], and 21 days [8-46], respectively); however, these differences were not statistically significant. CONCLUSION: Candidemia remains a significant problem in intensive care units patients. In the EPIC II population, Candida albicans was the most common organism and fluconazole remained the predominant antifungal agent used. Candida bloodstream infections are associated with high intensive care unit and hospital mortality rates and resource use