Ivanka Holclajtner-Antunović

Study of the matrix effect of easily and non-easily ionizable elements in an inductively coupled argon plasma. Part 1. Spectroscopic diagnostics

The influence of easily and non-easily ionizable concomitants on the spectral line profiles of the atomic and ionic components of analytes with different physical properties was investigated depending on the concentration of the concomitant and observation height above the load coil. The results obtained were considered from the point of view of nebulization and plasma discharge processes. For analytical reasons, all the investigations were performed in the normal analytical zone. The apparent temperatures of excitation, ionization and local thermal equilibrium and electron number density were measured, calculated and compared under plasma conditions with and without the presence of 20 mg ml–1 of Li and 50 mg ml–1 of Zn. It was found that the presence of Li changed the ionization temperature and non-equilibrium parameter (br) particularly in zones higher up in the plasma.

Large graphene quantum dots alleviate immune-mediated liver damage.

We investigated the effect of large (40 nm) graphene quantum dots (GQDs) in concanavalin A (Con A; 12 mg/kg i.v.)-induced mouse hepatitis, a T cell-mediated liver injury resembling fulminant hepatitis in humans. Intravenously injected GQDs (50 mg/kg) accumulated in liver and reduced Con A-mediated liver damage, as demonstrated by histopathological analysis and a decrease in liver lipid peroxidation and serum levels of liver transaminases. The cleavage of apoptotic markers caspase-3/PARP and mRNA levels of proapoptotic mediators Puma, Noxa, Bax, Bak1, Bim, Apaf1, and p21, as well as LC3-I conversion to autophagosome-associated LC3-II and expression of autophagy-related (Atg) genes Atg4b, Atg7, Atg12, and beclin-1, were attenuated by GQDs, indicating a decrease in both apoptosis and autophagy in the liver tissue. This was associated with the reduced liver infiltration of immune cells, particularly the T cells producing proinflammatory cytokine IFN-γ, and a decrease in IFN-γ serum levels. In the spleen of GQD-exposed mice, mRNA expression of IFN-γ and its transcription factor T-bet was reduced, while that of the IL-33 ligand ST2 was increased. The hepatoprotective effect of GQDs was less pronounced in ST2-deficient mice, indicating that it might depend on ST2 upregulation. In vitro, GQDs inhibited splenocyte IFN-γ production, reduced the activation of extracellular signal-regulated kinase in macrophage and T cell lines, inhibited macrophage production of the free radical nitric oxide, and reduced its cytotoxicity toward hepatocyte cell line HepG2. Therefore, GQDs alleviate immune-mediated fulminant hepatitis by interfering with T cell and macrophage activation and possibly by exerting a direct hepatoprotective effect.

Study of the matrix effect of easily and non-easily ionizable elements in inductively coupled argon plasma. Part 2. Equilibrium plasma composition

The matrix effect of easily and non-easily ionizable elements in an inductively coupled argon plasma is discussed in relation to the equilibrium plasma composition. The calculation procedure, based on the minimization of free energy, was applied in the temperature range 1000–9000 K, assuming the state of chemical equilibrium. The calculations were performed for ‘pure’ argon with water vapour and with the addition of Li, Ba and Zn. The influence of matrix elements on the emission intensities of Ca and Cd as analytes was also investigated.

Inhibition of rat synaptic membrane Na+/K+-ATPase and ecto-nucleoside triphosphate diphosphohydrolases by 12-tungstosilicic and 12-tungstophosphoric acid

The in vitro influence of Keggin structure polyoxotungstates, 12-tungstosilicic acid, H(4)SiW(12)O(40) (WSiA) and 12-tungstophosphoric acid, H(3)PW(12)O(40) (WPA), and monomer Na(2)WO(4) × 2H(2)O on rat synaptic plasma membrane (SPM) Na(+)/K(+)-ATPase and E-NTPDase activity was studied, whereas the commercial porcine cerebral cortex Na(+)/K(+)-ATPase served as a reference. Dose-dependent Na(+)/K(+)-ATPase inhibition was obtained for all investigated compounds. Calculated IC(50) (10 min) values, in mol/l, for SPM/commercial Na(+)/K(+)-ATPase, were: 3.4 × 10(-6)/4.3 × 10(-6), 2.9 × 10(-6)/3.1 × 10(-6) and 1.3 × 10(-3)/1.5 × 10(-3) for WSiA, WPA and Na(2)WO(4) × 2H(2)O, respectively. In the case of E-NTPDase, increasing concentrations of WSiA and WPA induced its activity reduction, while Na(2)WO(4) × 2H(2)O did not noticeably affect the enzyme activity at all investigated concentrations (up to 1 × 10(-3)mol/l). IC(50) (10 min) values, obtained from the inhibition curves, were (in mol/l): 4.1 × 10(-6) for WSiA and 1.6 × 10(-6) for WPA. Monolacunary Keggin anion was found as the main active molecular species present under physiological conditions (in the enzyme assays, pH 7.4), for the both polyoxotungstates solutions (1 mmol/l), using Fourier transform infrared (FT-IR) and micro-Raman spectroscopy. Additionally, commercial porcine cerebral cortex Na(+)/K(+)-ATPase was exposed to the mixture of Na(2)WO(4) × 2H(2)O and WSiA at different concentrations. Additive inhibition effect was achieved for lower concentrations of Na(2)WO(4) × 2H(2)O/WSiA (≤ 1 × 10(-3)/4 × 10(-6) mol/l), while antagonistic effect was obtained for all higher concentrations of the inhibitors.

Multi-analytical study of techniques and palettes of wall paintings of the monastery of Žiča, Serbia

The present multi-analytical study concentrates on establishing the painting techniques and the identity of the wall painting materials used by the artists from the 13th and 14th centuries to decorate the Žiča monastery, Serbia. For this purpose, we demonstrate that micro-Raman spectroscopy is an efficient, non-destructive method with high spatial resolution which gives molecular and crystal structural information of a wide variety of both inorganic and organic materials. It is shown that elementary composition revealed through scanning electron microscopy with energy dispersive X-ray spectroscopy and energy dispersive X-ray fluorescence spectroscopy is necessary in some cases to confirm the identity of pigments and binders identified by micro-Raman spectroscopy. It was found that a fresco technique, in combination with mainly natural earth pigments such as red ochre, yellow ochre and green earth, was used. Expensive natural pigment lapis lazuli was exclusively used for obtaining blue colour while pure vermilion was used by the artists from the first period of decorations at the beginning of the 13th century. A mixture of pigments was used for attaining different colour shades. For the gilding of saints haloes, thin golden foil was deposited over the tin sheet. In order to get a desirable optical and aesthetical impression, the metallic leaves were deposited over the yellow ochre preparatory layer. Deposits of gypsum on wall paintings as well as traces of weddellite are degradation products formed as a result of exposing wall paintings to environmental conditions.

Antibacterial potential of electrochemically exfoliated graphene sheets

Electrochemically exfoliated graphene is functionalized graphene with potential application in biomedicine. Two most relevant biological features of this material are its electrical conductivity and excellent water dispersibility. In this study we have tried to establish the correlation between graphene structure and its antibacterial properties. The exfoliation process was performed in a two electrode-highly oriented pyrolytic graphite electrochemical cell. Solution of ammonium persulfate was used as an electrolyte. Exfoliated graphene sheets were dispersed in aqueous media and characterized by atomic force microscopy, scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, X photoelectron spectroscopy, X-ray diffraction, electron paramagnetic resonance, zeta potential, contact angle measurements and surface energy. Antibacterial assays have shown lack of the significant antibacterial activity. Major effect on bacteria was slight change of bacteria morphology. Membrane remained intact despite significant change of chemical content of membrane components.

Raman Spectroscopy as a New Biochemical Diagnostic Tool

Summary In this review, Raman spectroscopy is described as a new and potentially powerful diagnostic tool in comparison to routine biochemical tests. Advanced instrumentation and new Raman spectroscopy techniques enable rapid and simultaneous identification and/or determination of several biochemical parameters, such as glucose, acetone, creatinine, urea, lipid profile, uric acid, total protein, etc, with a very low limit of detection. Raman spectroscopy could also be applied in molecule and cell characterization, as well as diagnostics of atherosclerosis in its early stage. Raman spectroscopy is nondestructive and could be applied to all kinds of samples, which simplifies the diagnostics of numerous diseases and pathologic states. Special attention is paid to literature data illustrating the application of Raman spectroscopy for transdermal glucose monitoring and cancer diagnostics. Kratak sadržaj U ovom prikazu opisana je primena Ramanske spektrosko- pije kao nove metode velikih mogućnosti u dijagnostici, u poređenju sa rutinskim biohemijskim testovima. Metoda je razvijena i usavršena za identifikaciju i/ili određivanje velikog broja biohemijskih parametara, kao što su glukoza, aceton, kreatinin, urea, lipidni profil, mokraćna kiselina, ukupni proteini i drugi, uz veoma nizak limit detekcije. Ramanska spek- troskopija takođe se može primenjivati u molekulskoj i ćelij- skoj karakterizaciji, kao i za dijagnostiku ranog stadijuma ateroskleroze. Ramanska spektroskopija je nedestruktivna i može se primenjivati na sve vrste uzoraka, što pojednostavljuje dijagnostiku brojnih bolesti i patoloških stanja. Posebna pažnja u radu je posvećena podacima iz literature koji ilustru- ju primenu Ramanske spektroskopije u transdermalnom monitoringu glukoze i dijagnostici kancera

Adsorption–desorption and catalytic properties of SBA-15 supported cesium salts of 12-molybdophosphoric acid for the dehydration of ethanol

Cesium salts of molybdophosphoric acid with varying amounts of the cations Cs1H2PMo12O40 and Cs3PMo12O40 have been prepared as pure or supported on SBA-15. The adsorption of ethanol and its temperature programmed desorption–TPD using thermogravimetry were studied for SBA-15 supported and unsupported Cs salts. The evolved gases during the adsorption–desorption of ethanol on CsHPM/SBA-15 composites were identified by online mass spectrometry coupled with thermogravimetry. The main products observed in the evolved gases during the desorption of ethanol were C2H4, C3H6 and unreacted ethanol. The amount of acidic sites of the composites was estimated by ammonia adsorption–desorption. The dehydration of ethanol was used to test the catalytic properties of the CsHPM samples incorporated on the silica matrix. SBA15—supported catalysts, appeared to be more active than bulk catalysts in vapor phase dehydration and dehydrogenation of ethanol reactions. The effect of the support leads to higher values of dehydration rates of ethanol as well as higher values of ethylene and acetaldehyde formation rates.

On plasma composition of a pulsed discharge in electrolyte

The equilibrium plasma composition for a system containing H, O, N, Na, and Cu is determined for the temperature range between 5000–20,000 K. This corresponds to the pulsed discharge plasma in electrolyte with energy dissipation which is near threshold. For computing the plasma composition of the system based on the minimization of free energy, the method of steepest descent was used. The plasma composition was calculated for different electrolyte contents, conductivity, and various external pressures.

Study of the decomposition pathway of 12-molybdophosphoric acid in aqueous solutions by micro Raman spectroscopy.

Micro Raman spectroscopy was applied to investigate the speciation of heteropoly and isopoly molybdates in 0.05 and 0.005 M aqueous solutions of 12-molybdophosphoric acid at pH values between 1 and 6. For comparative purposes, (31)P NMR spectroscopy was applied too. It is shown that stability of Keggin anion is influenced both by pH and concentration of solution. The Keggin structure is stable in acidic solutions (pH<1.6) while defective Keggin structures are formed with further alkalization (up to pH5.6). Monolacunary anion PMo11O(39)(7-) is the main component in the pH region from 1.6 to 3.4. Further removal of molybdenyl species causes the appearance of other vacant Keggin structures such as PMo9O31(OH)(3)(6-) and PMo6O(25)(9-) at about pH4. At pH5.0, anion PMo6O(25)(9-) is the main species. In solutions with pH greater than 5.0, heteropolymolybdates disappear completely and isopolymolybdates Mo7O(24)(6-) and MoO(4)(2-) are formed in higher amounts. In more diluted solution of 0.005 M, the decomposition scheme of 12-molybdophosphoric acid solution with increasing of pH takes place without observation of significant amounts of Mo7O(24)(6-) species. If alkalinization is performed with 0.5 M instead of 5 M NaOH, there are no significant changes in the Raman spectra of solutions. It is shown that the spectra of evaporated samples may be used for the identification of molecular species in corresponding concentrated solutions. However, Raman spectra of dry residues of more diluted solutions differ from spectra of corresponding solutions due to the reactions performed during the process of drying and cannot be used for unambiguous identification of species in solution. Acidification of 0.05 M solution of Na2MoO4 shows that at pH>5.6, molybdate anion MoO(4)(2-) dominates, while in the pH range between 5.6 and 1, heptamolybdate anion Mo7O(24)(6-) is preferentially formed.