41 research outputs found
Design, physico-chemical characterisation, toxicity and application of newly class of functionalized ionic liquids
U ovoj doktorskoj disertaciji sintetisane su dve različite klase jonskih tečnosti, na bazi imidazolijuma i holinijuma, sa ciljem snižavanja toksičnosti. Imidazolijumove jonske tečnosti su funkcionalizovane hidroksilnom i etarskom grupom u bočnom lancu. Uspešnost sinteza jonskih tečnosti potvrđena je snimanjem IC i NMR spektara. Izmerene su gustine, viskoznosti i provodljivosti čistih imidazolijumovih i holinijumskih jonskih tečnosti. Na osnovu dobijenih eksperimentalnih rezultata,potpomognutim računarskim simulacijama diskutovana je strukturna organizacija između katjona i anjona. Utvrđeno je da prisustvo hidroksilne grupe u bočnom lancu imidazolovog katjona, značajno utiče na lokaciju anjona i samim tim na makroskopska svojstva. U nastavku su izmerene gustine i viskoznosti vodenih rastvora sa ciljem dobijanja informacija o uticaju dodatka holinijumskih i imidazolijumovih jonskih tečnosti na strukturu vode. Na osnovu B koeficijenta iz viskoznosti, ekspanzibilnosti i rezultata simulacija molekulske dinamike, utvrđeno je da sve jonske tečnosti imaju structure making osobine. Takođe, na osnovu izračunatih specifičnih molarnih zapremina i doking analize na receptoru za gorak ukus, ustanovljeno je da vodeni rastvori holinijumskih jonskih tečnosti imaju gorak ukus. Toksičnost funkcionalizovanih imidazolijumovih jonskih tečnosti ispitana je na nekoliko biljnih vrsta (pšenica, ječam i krastavac), kao i na larvama A. salina i ćelijskoj liniji MRC-5. Potvrđeno jeda uvođenje hidroksilne grupe u alkil niz najviše se redukuju toksičnosti imidazolijumovih jonskih tečnosti, dok je uticaj etarske grupe na smanjenje toksičnosti značajno manji. Ispitivanje citotoksičnosti i antibakterijske aktivnosti ukazalo je da holinijumske jonske tečnosti se mogu smatrati netoksičnima, i pokazuju beningnije dejstvo u poređenju sa njihovim polaznim komponentama (askorbinska kiselina, biotin i nikotinska kiselina).In this doctoral thesis, ionic liquids based on imidazolium and cholinium cation were synthesized, in order to obtain new class of ILs with reduced toxicity. Imidazolium based ionic liquids were functionalized with hydroxyl and ether group in order to reduce their lipophilicity. All newly synthesized compounds were confirmed by measuring IR and NMR spectra. For pure ionic liquids, density, conductivity and viscosity were measured. Based on the obtained experimental results supported with results of molecular simulations, it was concluded that presence of oxygen in alkyl side chain of imidazolium ionic liquids significantly contribute to position of anion. Further, density and viscosity of diluted aqueous ILs solutions were measured with a purpose to investigate their influence on water structure. Based on obtained values for viscosicty B coefficient, expansibility and from MD simulations, all ionic liquids express structure making tendency. From calculated specific apparent molar volumes for cholinium ionic liquids it was noted bitter taste. The toxicity of functionalized imidazolium ionic liquids was investigated on different plant species (wheat , barley and cucumber), on larvae of A. salina and cell line MRC-5. From obtained results it was concluded that introduction of hydroxyl group in alkyl side chain reduce toxicity significantly more than ether group. Experiments on cytotoxicicity and antibacterial effects allowed to conclude that those newly synthesized cholinium ionic liquids can be considered as non-toxic
Ionic liquids as potentially new antifungal agents against Alternaria species
The fungal genus Alternaria Nees 1816 includes the most prevalent pathogenic species that can cause crop diseases such as blight, black spot, and dark leaf spot. In accordance with the aim of developing modern sustainable approaches in agriculture for the replacement of synthetic and toxic substances with environmentally friendly alternatives, the objective of this study was to examine thein vitro antifungal activities of 18 newly synthesized ionic liquids (ILs) against three Alternaria strains: A. padwickii, A. dauci and A. linicola. The antifungal activities of the ILs were estimated via a microdilution method to establish minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) values. The results confirmed that 17 of the 18 ILs showed strain specificity, including good antifungal activity toward Alternaria strains, with MIC and MFC values in the range of 0.04 to 0.43 mol dm(-3). The strongest antifungal effects toward all analyzed Alternaria strains were displayed by the compounds with long alkyl chains: [omim][Cl] (MIC/MFC: 0.042 mol dm(-3)), [dmim][Cl] (MIC/MFC: 0.043 mol dm(-3)), [ddmim][Cl] (MIC/MFC: 0.053 mol dm(-3)), [ddTSC][Br] (MIC/MFC: 0.053 mol dm(-3)), and [Allyl-mim][Cl] (MIC/MFC: 0.054 mol dm(-3)). The introduction of oxygen as a hydroxyl group resulted in less-pronounced toxicity towards Alternaria compared to the introduction of an ether group, while the contribution of the hydroxyl group was shown to be a more determining factor than the prolongation of the side-chain, resulting in overall fungicidal activity decrease. Our results indicate the possibility that the most effective ILs ([Allyl-mim][Cl], [omim][Cl], [dmim][Cl], [ddmim][Cl], [bTSC][Br], [hTSC][Br], [oTSC][Br], [dTSC][Br], and [ddTSC][Br]) could be applied to the control of plant diseases caused by Alternaria species, based on their potential as an environmentally friendly crop protection approach. Since salts based on TSC cations are significantly cheaper to synthesize, stable under mild conditions, and environmentally friendly after degradation, thiosemicarbazidium-based ILs can be a suitable replacement for commercially available imidazolium ILs
High pressure densities of ethylene glycol and caffeine mixtures
Ethylene glycol is a well-known fluid that is recognized for its application in heat transfer processes [1]. In order to improve its characteristics and performances, adding other particles in the mixture of ethylene glycol and water, such as nanoparticles has been investigated [2]. A substance widespread available, easily distributed and cost effective is caffeine. Caffeine can be recycled from coffee or tea waste, which makes it profitable and sustainable. Literature data state that caffeine addition to ethylene glycol improves its properties as a heat transfer fluid, primarily due to higher heat capacities, higher system fluidity and lower viscosity [3]. This work investigates different thermodynamic properties of caffeine + ethylene glycol mixtures. Densities have been measured at high pressures from
(0,1 – 60) MP and at the temperature range (20 - 140) ºC. All measurements were performed using an Anton Paar DMA 5000 HP density meter with a vibrating tube [4]. The obtained results were fitted by the modified Tammann-Tait equation and parameters were used to determine the isothermal compressibility coefficient, the coefficient of isobaric expansion, the internal pressure and the difference of specific heat capacity at constant pressure and constant volume. Experimental values and calculated thermodynamic parameters reported in this work will help in concluding whether the caffeine + ethylene glycol mixtures are good candidates as heat transfer fluids
Distribution and diversity of brown frogs (Rana spp., Anura, Amphibia) in Serbia
In this study, we present updated distribution data for all three brown frog species (Rana spp.) inhabiting Serbia. The data provided consists of newly collected field records and compiled data previously published in literature or via Internet. Of the three species found in Serbia, Rana dalmatina is the most widespread, present in all three altitudinal regions and all biogeographical regions. Rana graeca is confined to Mountain-valley altitudinal region in permanent fastflowing rivers or streams and it reaches its northern range boundaries in Serbia. Rana temporaria is the rarest of the three, with fragmented range restricted to the high mountains or few isolated lowland populations, and in the north-eastern Serbia, it is vicariant with R. graeca in canyons and gorges of montane rivers. The presence of Rana arvalis in Serbia is mentioned in literature but was not confirmed during the subsequent field surveys, so we consider it only as a potential species for the Serbian batrachofauna. The brown frog faunal composition of Serbia is identical to that of Albania, Bosnia and Herzegovina, Bulgaria, Greece, Macedonia and Montenegro, while it is somewhat different from that of Hungary and Romania and the most different from Croatia and Slovenia. Serbian brown frogs belong to European (R. temporaria) and South-European (R. dalmatina, R. graeca) chorotypes. All species of brown frogs present or potentially present in Serbia and their habitats are identified as great conservation priorities
Tuning of Molecular Water Organization in Water-in-Salt Electrolytes by Addition of Chaotropic Ionic Liquids
Water-in-salt electrolytes (WISEs) have expanded the useful electrochemical stability of water, making the development of functional aqueous lithium-ion batteries more accessible. The implementation of additives in the formulation of WISEs can further improve the electrochemical stability of water and avoid potential lithium-ion salt solubility issues. Here, we have used Gemini-type ionic liquids to suppress water activity by designing the structure of ionic-liquid cations. The different water-organizing effects of ionic-liquid cations have been investigated and correlated to battery performance in LTO/LMO full cells. The champion device, containing the most chaotropic ionic liquid, retained at least 99% of its Coulombic efficiency after 500 charging cycles, associated with a final specific discharge capacity of 85 mA h·g-1. These results indicated that water-rich Li+ solvation shells significantly contribute to the excellent device performance and long-term stability of the LTO/LMO-based full battery cells. This work shows that the fine-tuning of the Li+ solvation shell and water structure by the addition of chaotropic cations represents a promising strategy for generating more stable and effective lithium-ion-containing rechargeable aqueous batteries. The work was supported by the Swedish Energy Agency contract no. 50119-1, entitled “Be WiSE─Robotic screening of water-in-salt electrolytes (WiSE) for environmental batteries” and the Swedish Research Council contract no. 2020-06701.</p
Impulse oscillometry in evaluation bronchial hyperresponsivness in patients with persistent allergic rhinitis
Background/Aim. Impulse oscillometry (IOS) is a method for estimating lung function which is used for early detection of bronchial hyperresponsiveness (BHR) and asthma. The aim of the study was to determine the prevalence of BHR, the correlation between spirometry and IOS and sensitivity and specificity of IOS in proving BHR in patients with persistent allergic rhinitis. Methods. The study included 81 patients with allergic rhinitis. From all of them, medical history was taken, allergy testing was done, as well as measurements of parameters of lung function by the IOS and spirometry before and after nonspecific bronchial provocation test with histamin via Aerosol provocative system. Changes of the IOS parameters to fall in FEV1 of 20% were measured and compared with changes in the spirometry parameters. After bronchial challenge test subjects were divided into two groups: the group with BHR (group 1) and that without BHR (group 2). Results. The mean age of participants was 25.7 ± 5.7 years, and 50.5% were men. Out of the total number of subjects with allergy rhinitis, 56 (58.9%) had a positive BPT. After bronchoprovocation an average increase in the group 1 was 88.15% for Rrs5, 111.98% for Fres, and for AX 819.69%. The high degree of correlation between the IOS and spirometry was proven in the group 2, while the whole group 1 had a weak correlation between parameters of these two methods. High sensitivity and low specificity for Rrs5 and Fres compared to FEV1 in diagnosing BHR was proven. Conclusion. The study demonstrated a high prevalence of BHR in the study group of patients with persistent allergic rhinitis, poor correlation in relation to the spirometric measurements in the group with BHR and a high sensitivity and low specificity of IOS for the detection of early changes in the airways
Tuning of Molecular Water Organization in Water-in-Salt Electrolytes by Addition of Chaotropic Ionic Liquids
Water-in-salt electrolytes (WISEs) have expanded the useful electrochemical stability of water, making the development of functional aqueous lithium-ion batteries more accessible. The implementation of additives in the formulation of WISEs can further improve the electrochemical stability of water and avoid potential lithium-ion salt solubility issues. Here, we have used Gemini-type ionic liquids to suppress water activity by designing the structure of ionic-liquid cations. The different water-organizing effects of ionic-liquid cations have been investigated and correlated to battery performance in LTO/LMO full cells. The champion device, containing the most chaotropic ionic liquid, retained at least 99% of its Coulombic efficiency after 500 charging cycles, associated with a final specific discharge capacity of 85 mA h<middle dot>g(-1). These results indicated that water-rich Li+ solvation shells significantly contribute to the excellent device performance and long-term stability of the LTO/LMO-based full battery cells. This work shows that the fine-tuning of the Li+ solvation shell and water structure by the addition of chaotropic cations represents a promising strategy for generating more stable and effective lithium-ion-containing rechargeable aqueous batteries
Informacioni sistem za analizu uspeha studenata / Students' achievement analysis system
Analiza ispitnog roka i vođenje evidencije o ispitima studenata na Odseku logistike Vojne akademije zahteva mnogo truda i vremena. Postoje pokušaji da se taj proces pojednostavi i automatizuje, ali se oni nisu pokazali dovoljno efikasnim. Ovim projektom omogućeno je da korisnik u mrežnom okruženju ostvari što efikasniji pristup informacijama. / The analysis of students' achievements and the examination results recording at the Military Academy (Department of Logistics) is a demanding and time-consuming task. Some efforts were put forth to make that process easier but they did not prove to be efficient enough. The main objective of this project is to make a system that will provide more efficient access to the information users need in network environment
Application of biodegradable cholinium ionic liquids for the extraction of 5-hydroxymethylfurfural (HMF) from honey
5-Hydroxymethylfurfural (HMF), a Maillard reaction product, can be formed when honey is subjected to heat treatment or a long storage time, becoming volatile and toxic depending on its concentration. The fact that, until today, there is no literature data on the extraction of 5-hydroxymethylfurfural (HMF) from honey using ionic liquids directed the investigation of the influence of biodegradable cholinium ionic liquids on the formation of aqueous biphasic systems and the application of these systems for the extraction of HMF from honey. The influence of anions of synthesised ionic liquids on the construction of biphasic systems in which an inorganic salt was used as a salting agent was investigated. Then, the extraction of HMF in these systems was examined, and the mechanisms of HMF extraction using ionic liquids were explained using computer simulations. Examining the effect of cholinium ionic liquids (choline chloride ([Ch][Cl]), cholinium nicotinate ([Ch][Nic]), cholinium propionate ([Ch][Prop]), and cholinium butyrate ([Ch][But])) on the formation of aqueous biphasic systems by comparing the phase diagrams, it was concluded that the ability of ionic liquids to form an aqueous biphasic system with tripotassium phosphate (K3PO4) decreases in the following order: [Ch][But] z [Ch][Prop] > [Ch][Nic] > [Ch][Cl]. By applying all tested aqueous biphasic systems for the extraction of HMF from honey, an extraction efficiency of more than 89% was achieved. Complete extraction was achieved using the extraction system with [Ch][But], while the weakest ability to extract HMF was exhibited by the system with [Ch][Cl]. The mechanisms of HMF extraction using ionic liquids are explained on the basis of the optimised structures of the ionic liquid systems with HMF, together with the visualisation of noncovalent interactions, and on the basis of the calculated binding energies DGbin, which can be used as a good predictor of the extraction potential of newly synthesised ionic liquid
Physicochemical characterization of choline based ionic liquids with chelating anions
In this paper, physicochemical characterization of newly synthesized choline based ionic liquids with five different chelating anions were examined. The ionic liquids (ILs): cholinium-L-lactate, [Ch][Lac], cholinium-picolinate, [Ch][Pic], cholinium-anthranilate, [Ch][Ant], cholinium-oxyquinolinate, [Ch][oQ], and cholinium-diethylenetriaminepentaacetate, [Ch]3[DTPA], were prepared for the first time and their structures were confirmed by IR and 1H and 13C NMR spectra. Also, thermogravimetric analysis (TGA) was applied to determine their thermal stabilities. Based on the measured density values and viscosity in the temperature range from (293.15 to 323.15) K and calculated values of thermal expansion coefficients and activation energy of viscous flow, as well as of computational simulations, the interactions and structures of the investigated ionic liquids were discussed. © 2018 Elsevier Lt