Nanostructured materials for sensing Pb(II) and Cd(II) ions: Manganese oxohydroxide versus carbonized polyanilines?

Nanostructured materials including three different carbonized polyanilines and manganese oxyhydroxide were prepared and evaluated as electrode materials for sensing of lead and cadmium ions in aqueous media. Anodic stripping voltammetry results indicated that all prepared materials could be successfully used for determination of these two heavy metal ions. Carbonized polyaniline-based electrodes have higher signal and lower limits of detection (10-7 М) compared to manganese oxyhydroxide-based electrode. Among the three studied carbonized polyanilines, the one that was derived from polyaniline precursor produced in the presence of 3,5-dinitrosalicyclic acid showed the highest electrocatalytic activity towards the lead and cadmium oxidation. [Projekat Ministarstva nauke Republike Srbije, br. OI172043 i br. III45014

Noncommutative SO(2,3)⋆SO(2,3)_{\star} Gauge Theory of Gravity

Topological gravity (in the sense that it is metric-independent) in a $2n$-dimensional spacetime can be formulated as a gauge field theory for the AdS gauge group $SO(2,2n-1)$ by adding a multiplet of scalar fields. These scalars can break the gauge invariance of the topological gravity action, thus making a connection with Einstein's gravity. This review is about a noncommutative (NC) star-product deformation of the four-dimensional AdS gauge theory of gravity, including Dirac spinors and the Yang-Mills field. In general, NC actions can be expanded in powers of the canonical noncommutativity parameter $\theta$ using the Seiberg-Witten map. The leading-order term of the expansion is the classical action, while the higher-order $\theta$-dependent terms are interpreted as new types of coupling between classical fields due to spacetime noncommutativity. We study how these perturbative NC corrections affect the field equations of motion and derive some phenomenological consequences, such as NC-deformed Landau levels of an electron. Finally, we discuss how topological gravity in four dimensions (both classical and noncommutative) appears as a low-energy sector of five-dimensional Chern-Simons gauge theory in the sense of Kaluza-Klein reduction.Comment: 18 pages; Contribution to the special issue of the European Physical Journal on "Noncommutativity and Physics

Electrochemical Sensing of Cadmium and Lead Ions in Water by MOF-5/PANI Composites

For the first time, composites of metal-organic framework MOF-5 and conjugated polymer polyaniline (PANI), (MOF-5/PANI), prepared using PANI in its conducting (emeraldine salt, ES) or nonconducting form (emeraldine base, EB) at various MOF-5 and PANI mass ratios, were evaluated as electrode materials for the electrochemical detection of cadmium (Cd2+) and lead (Pb2+) ions in aqueous solutions. Testing of individual components of composites, PANI-ES, PANI-EB, and MOF-5, was also performed for comparison. Materials are characterized by Raman spectroscopy, scanning electron microscopy (SEM) and dynamic light scattering (DLS), and their electrochemical behavior was discussed in terms of their zeta potential, structural, morphology, and textural properties. All examined composites showed high electrocatalytic activity for the oxidation of Cd and Pb to Cd2+ and Pb2+, respectively. The MOF/EB-1 composite (71.0 wt.% MOF-5) gave the highest oxidation currents during both individual and simultaneous detection of two heavy metal ions. Current densities recorded with MOF/EB-1 were also higher than those of its individual components, reflecting the synergistic effect where MOF-5 offers high surface area for two heavy metals adsorption and PANI offers a network for electron transfer during metals’ subsequent oxidation. Limits of detection using MOF/EB-1 electrode for Cd2+ and Pb2+ sensing were found to be as low as 0.077 ppm and 0.033 ppm, respectively. Moreover, the well-defined and intense peaks of Cd oxidation to Cd2+ and somewhat lower peaks of Pb oxidation to Pb2+ were observed at voltammograms obtained for the Danube River as a real sample with no pretreatment, which implies that herein tested MOF-5/PANI electrodes could be used as electrochemical sensors for the detection of heavy metal ions in the real water samples

Simultaneous determination of amoxicillin and clavulanic acid in the human plasma by high performance liquid chromatography: Mass spectrometry (UPLC/MS)

Background/Aim. Quantitative analysis of amoxicillin and clavulanic acid in biological matrices requires sensitive and specific methods which allow determination of therapeutic concentration in μg/mL range. Analytical methods for determination of their concentrations in body fluids described in literature include high performance liquid chromatography coupled to UV detector (HPLC-UV) and liquid chromatography-mass spectrometry (LC-MS). The aim of this study was to develop sensitive and specific ultra performance liquid chromatography/ mass spectrometry (UPLC/MS) method which could be used for the spectral identification and quantification of the low concentrations of amoxicillin and clavulanic acid in the human plasma. Method. A sensitive and specific UPLC/MS method for amoxicillin and clavulanic acid determination was developed in this study. The samples were taken from the adult healthy volunteers receiving per os one tablet of amoxicillin (875 mg) in combination with clavulanic acid (125 mg). Results. Plasma samples were pretreated by direct deproteinization with perchloric acid. Quantification limit of 0.01 μg/ml for both amoxicillin and clavulanic acid was achieved. The method was reproducible day by day (RSD < 7 %). Analytical recoveries for amoxicillin ranged from 98.82% to 100.9% (for concentrations of 1, 5 and 20 μg/mL), and recoveries for clavulanic acid were 99,89% to 100.1% (for concentrations of 1, 2 and 5 μg/mL). This assay was successfully applied to a pilot pharmacokinetic study in healthy volunteers after a single-oral administration of amoxicillin/ clavulanic combination. The determined plasma concentrations of both amoxicillin and clavulanic acid were in the range of the expected values upon the literature data for HPLC-UV and LC-MS methods. Conclusion. The described method provided a few advantages comparing with LC/MS-MS method. The method is faster using running time of 5 minute, has lower limit of quantification (LOQ ) and it could be used in pharmacokinetic studies of both amoxicillin and clavulanic acid

Polyphenolics and Chemical Profiles of Domestic Norwegian Apple (Malus x domestica Borkh.) Cultivars

Using modern analytical techniques, a comprehensive study of the chemical composition of fruits from apple cultivars grown in Western Norway during 2019 and 2020 was done. Metals, sugars, organic acids, antioxidant tests, and polyphenol content have been observed. In all investigated samples, the most dominant sugars were glucose, fructose, and sucrose. Among 11 tested organic acids, the dominant was malic acid, followed by citric and maleic acid. The most common metal was potassium, followed by magnesium and zinc. The quantification of polyphenols showed that among the 11 quantified polyphenols, chlorogenic acid, quercetin 3-O-rhamnoside, quercetin 3-O-glucoside, quercetin, and phlorizin were the most abundant. A detailed study of the polyphenolic profile of nine investigated apple samples provided 30 identified polyphenolic compounds from the class of hydroxybenzoic and hydroxycinnamic acids, flavonoids, and dihydrochalcones. In addition to the identified 3-O-caffeoylquinic acid, its two isomers of 5-O-caffeoylquinic acid and three esters were also found. Present polyphenols of the tested apples provided significant data on the quality of Norwegian apples, and they contribute to the distinguishing of these apple samples.publishedVersio

Antioksidantne karakteristike klijanaca soje gajenih na različitim tipovima zemljišta

The purpose of this work was to assess change in antioxidant ability and accumulation of antioxidants in soybean seedlings, as well as some morphological parameters (plant height, shoot and root mass) during abiotic stress. Activity of antioxidant enzymes [superoxide dismutase (SOD; EC 1.15.1.1) and peroxidases (GPX-guaiacol peroxidase and PPX-pyrogallol peroxidase, EC 1.11.1.7)], phenylalanine ammonia lyase (PAL; EC 4.3.1.5), as well as content of non-enzymatic antioxidants (total phenolics, tannins and flavonoids) were analyzed in leaves of soybean seedlings grown in different soil types [mollic vertisol (humic); calcic chernozem (calcic) and haplic fluvisol (calcaric)]. Seedlings grown in fluvisol had significantly higher activity of SOD (7.5-8.6%) and PAL (39.2-43.0%) in leaves, as well as total phenolics and tannins content (8.1-80.7%) in comparison to those grown in chernozem and vertisol. However, soybean grown in chernozem had the most favourable conditions for growth and the highest total flavonoids content (2.3 mg rutin g-1 dry weight). Regardless the difference in response to higher and lower level of soil fertility, soybean seedlings grown in vertisol and fluvisol had similar morphological properties, which showed the great ability of their antioxidant systems to acclimate to change in soil quality.Cilj ovog rada bio je da se utvrdi da li akumulacija antioksidanata i promene u antioksidantnoj sposobnosti u klijancima soje utiču na morfološke parametre (visinu biljke i masu nadzemnog i podzemnog dela biljke). Analizirane su promene u aktivnosti antioksidantnih enzima [superoksid-dismutaze (SOD; EC 1.15.1.1) i peroksidaza (GPX-gvajakol i PPX-pirogalol peroksidaze, EC 1.11.1.7)], fenilalanin amonijum-lijaze (PAL; EC 4.3.1.5), kao i sadržaju neenzimskih antioksidanata (ukupnih fenola, tanina i flavonoida) u listu klijanaca soje gajene na različitim tipovima zemljišta [ritska crnica, černozem i fluvisol]. U listu klijanaca soje gajenih na fluvisolu zabeležena je značajno veća aktivnost superoksid-dismutaze (7.5-8.6%) i fenilalanin amonijum-lijaze (39.2-43.0%, kao i sadržaj ukupnih fenola i tanina (8.1-80.7%) u odnosu na klijance gajene na černozemu i ritskoj crnici. Ipak, klijanci soje gajeni na černozemu imali su najbolje uslove za rast i razvoj, kao i najveći sadržaj flavonoida (2.3 mg rutina g-1 suve mase). Pored toga, morfološke karakteristike klijanaca soje gajenih na ritskoj crnici i fluvisolu se nisu značajno razlikovale, što navodi na zaključak na izuzetno izraženu adaptabilnost antioksidantnog sistema ovih biljaka na promene u kvalitetu zemljišta

Chemical Fruit Profiles of Different Raspberry Cultivars Grown in Specific Norwegian Agroclimatic Conditions

Raspberries are considered valuable fruits due to their high levels of nutrients and phytochemicals, which have many beneficial effects on humans. As many external factors affect the composition of these fruits (the type of cultivation, soil characteristics, ripeness, storage time and post-harvest technologies, cultivar/genotype, and climatic conditions), the goal of this study was to analyze different raspberry cultivars grown in Norway. Considering that Norway is a country with specific climatic conditions, as well as has a limited period of fruit vegetation, another important goal of this study was also to compare raspberries from different Norwegian areas, as well as different grown cultivars. Modern analytical techniques, such as high-performance anion-exchange liquid chromatography with pulsed amperometric detection (HPEAC-PAD), ultra-high-performance liquid chromatography with diode array detector coupled to triple quadrupole mass spectrometry (UHPLC-DAD MS/MS), and inductively coupled plasma–optical emission spectrometry (ICP-OES), provided a detailed examination of the raspberry extract samples. Based on their high levels of minerals (especially N, P, and K), organic acids (predominantly citric and malic acids), sugars (glucose, fructose, sucrose, and galactose), and polyphenols (ellagic acid, syringic acid, quercetin, and rutin), Norwegian raspberries could be considered fruits with increased health-beneficial compounds. The chemical composition of the studied cultivars depended on the locality of growth.publishedVersio

Past studies and potential measures for rehabilitation of the shallow lake (Lake Ludas)

Lake Ludaš has been under a strong anthropogenic influence for a very long time, so the history of fruitful scientific investigation was very often connected with the evaluation of a human impact and potential rehabilitation measures. Unfortunately, attempts to improve the lake's natural status remain more in the field of theoretical models than concrete practical solutions. Aiming to better understand the potential of different rehabilitation measures for Lake Ludaš, we combined our ecological analyses (unpublished results) and the literature survey. The continuous massive cyanobacterial bloom and the formation of a thick sediment layer rich in different organic and inorganic pollutants represent two major challenges in the lake's rehabilitation. The unknown ecological role of invasive species that have already colonised Lake Ludaš will make the attempts to improve conditions in the lake even more challenging. The reduction of nutrient load, changes in the intensity and directions of water circulation, as well as top sediment layer removal in the lake, are measures under consideration for several decades. But their combination, order of implementation and possibilities of successful execution are still under debate. However, there is no doubt that the restoration of a natural hydrological regime should be a key step in the rehabilitation of Lake Ludaš

Određivanje morfina, kodeina i 6-monoacetilmorfina metodom HPLC/MS u salivi heroinskih zavisnika

Background/Aim. Saliva represents an alternative specimen for substances abuse determination in toxicology. Hence, the aim of this study was to optimize a method for saliva specimen preparation for heroin metabolites, morphine and 6-monoacetylmorphine (6-mam), and codeine determination by liquid chromatography-mass spectrometry (LC/MS), and to apply this method on saliva samples taken from the patients. Methods. Saliva specimen was prepared using liqiud/liquid extraction of morphine, codeine and 6- mam by mixture of chloroform and isopropanol (9 : 1; v/v). Extracts were analysed by HPLC/MS technique: separation column Waters Spherisorb® 5 μm, ODS2, 4.6 × 100 mm; mobile phase: ammonium acetate : acetonitile (80 : 20; v/v), mobile phase flow rate 0.3 mL/min; mass detection range: 100-400 m/z. Regression and correlation analyses were performed with the probalility level of 0.05. Concentrations of morphine, codeine and 6-mam were determined in saliva samples of the patients with 'opiates' in urine identified by the test strips. Results. Calibration for each analysed substance was done in the concentration range from 0.1 to 1 mg/L and the coefficient of correlation was R2 > 0.99. We obtained following calibration curves: y = 385531x + 14584; y = 398036x + 31542; and y = 524162x - 27105, for morphine, codeine and 6-mam, respectively. Recovery for morphine and codeine determination was 99%, while for 6- mam it was 94%. Limits of detection and quantification of a proposed method were 0.01 mg/L and 0.05 mg/L, respectively. Concentration of morphine in the saliva of the heroin users ranged between 0.54 and 5.82 mg/L, concentration of codeine between 0.05 and 5.33, and 6-mam between 0.01 and 0.68 mg/L. A statistically significant correlation between codeine and 6-mam concentrations was obtained. Conclusion. A proposed HPLC/MS method for morphine, codeine and 6-mam determination in saliva is accurate, simple, cheap and suitable for routine analysis and monitoring of heroin abuse.Uvod/Cilj. Saliva predstavlja alternativni matriks za identifikaciju sredstava zloupotrebe. Cilj ovog rada bio je optimizacija metode pripreme uzorka salive i određivanja metabolita heroina, morfina i 6-monoacetilmorfina (6-mam), i kodeina liquid chromatography-mass spectrometry (LC/MS) metodom i provera metode u realnim uslovima kod heroinomana. Metode. Priprema uzoraka vršena je tečno-tečnom ekstrakcijom uz smešu hloroforma i izopropil alkohola u odnosu 9 : 1. Ekstrakti su analizirani tehnikom HPLC/MS: razdvajanje na koloni Waters Spherisorb® 5 μm, ODS2, 4,6 × 100 mm, vršeno je primenom mobilne faze amonijum-acetat : acetonitril u odnosu 80 : 20 pri protoku od 0,3 mL/min. Masena detekcija je vršena u opsegu masa od 100 do 400 m/z. Primenjene su regresiona i korelaciona analiza za nivo verovatnoće 0,05. Određivanje prisustva morfina, kodeina i 6-mam vršeno je u uzorcima salive kod osoba kod kojih je test trakama utvrđeno prisustvo 'opijata' u urinu. Rezultati. Kalibracija je vršena u opsegu koncentracija 0,1-1 mg/L sa koeficijentom determinacije R2 > 0,99. Dobijene su kalibracione krive: za morfin, y = 385531x + 14584; kodein, y = 398036x + 31542 i 6- monoacetilmorfin, y = 524162x - 27105. Recovery vrednosti za određivanje morfina i kodeina iznosile su 99%, a za 6-mam 94%. Limit detekcije predložene metode iznosio je 0,01 mg/L, a limit kvantifikacije 0,05 mg/L. U salivi uživalaca heroina koncentracija morfina kretala se u opsegu od 0,54 do 5,82 mg/L, kodeina od 0,05 do 5,33, a 6-mam od 0,01 do 0,68 mg/L i dobijena je statistički značajna korelacija između vrednosti za kodein i 6-mam. Zaključak. Predložena HPLC/MS metoda za određivanje sadržaja morfina, kodeina i 6-monoacetilmorfina u salivi je tačna, jednostavna, ekonomična i pogodna za rutinsku primenu, kao i za biomonitoring zloupotrebe heroina

Cymbopogon citratus essential oil: an active principle of nanoemulsion against Enterococcus faecalis root canal biofilm

Aim: The objective was to formulate and characterize the nanoemulsion based on Cymbopogon citratus oil, intended for use in infected teeth root canal therapy. The investigation of the antioxidant and antibiofilm potential toward Enterococcus faecalis was aimed as well. Materials & methods: Characterization of oil (by GC/MS analysis) and nanoemulsion (by dynamic light scattering instrument), and determination of antibacterial (by microdilution assay), antibiofilm (by crystal violet assay) and antioxidant properties (by 2,2-diphenyl-1-picryl-hydrazyl-hydrate and thiobarbituric acid assay methods) were provided. Antibiofilm efficacy of irrigation procedure including nanoemulsion was screened on extracted teeth (by CFU-counting assay). Results: Notable antibacterial and antibiofilm activity, both against forming and preformed biofilms of oil, was observed. Irrigation involved nanoemulsion showed remarkable antibiofilm potential. Both substances induced some antioxidant activity. Conclusion: Results encourage further research with the aim of application of the nanoemulsion in dental practice