Copper content of vineyard soils at Sremski Karlovci (Vojvodina Province,Serbia) as affected by the use of copper-based fungicides

The present study investigated the copper content of nine vineyard plots soils and four control plots as affected by the application of copper-based fungicides. The study was carried out at the site of Sremski Karlovci in the Serbian province of Vojvodina. The results showed that Cu soil concentrations are increased at the site and that there is a tendency towards soil contamination by this element. Of the 27 total samples studied, only one had Cu concentration above the maximum allowable concentration of 100?mg?kg^?1. That sample's concentration was 111.7?mg?kg^?1. All the samples from the 0–15?cm layer had copper levels that were above the critical value of 60?mg?kg^?1. The mean value of the samples was 79.4?mg?kg^?1, contrasting with the background concentration of 19.8?mg?kg^?1. The results obtained for the studied vineyard soils indicate that these soils are potentially at risk and call for reduced application of Cu-based fungicides along with soil monitoring.     

Investigation of Lublin town environment contamination by radionuclides and heavy metals with application of Parmeliaceae lichens

Contamination of ground level air at Lublin town was studied by measurements of radioactive isotope and heavy metal contents in Parmeliaceae lichens exposed during six months on the area of the town. The concentration of the elements studied was compared with these ones measured in unexposed (blank) samples of lichens. The highest increase of radioactivity was noticed for ²³²Th, ²²⁶Ra and ⁴⁰K. The contamination by ¹³⁷Cs does not increased markedly, ranging from 2 to 107 Bq/kg of the dry lichen sample. Nearly half of the exposed samples do not reveal any increase of cesium radioactivity. Heavy metal concentrations in analyzed lichens were low. From the results obtained, one may conclude that concentration of these metals in ground air level does not reach appreciable values.     

Complexes of Fluorinated β-Diketonates of Neodymium for Nd-Containing Liquid Organic Scintillators

Volatile complexes of fluorinated β-diketonates of neodymium(III) (hexafluoroacetylacetonates with glyme and diglyme and decafluoroacetylacetonate with glyme) were studied for applicability in lowbackground Nd-containing organic liquid scintillators. The complexes were prepared in one step and purified by vacuum sublimation. The composition of complexes was determined by ¹H, ¹⁹F, and ¹³C NMR and IR spectroscopy and confirmed by elemental and functional analysis. It was shown that these adducts are suitable for the design of Nd-containing organic liquid scintillators with neodymium concentration of ~1–2 g/L.     

Thermokinetic Studies on the Activation of Arginase by Glycine

The activation of bovine liver arginase, which catalyzes the hydrolysis of L‐arginine to L‐ornithine and urea, by glycine was studied by thermokinetic methods at 37°C in 40 mmol·L^?1 sodium barbiturate‐HCl buffer solution (pH 9.4). Results of this experiment indicate that an appropriate concentration of glycine can enhance the activity of arginase, and the relative activation rate reached its maximum value, 74%, when the concentration of glycine in reaction system was 1 mmol·L^?1 and the initial concentration of arginine was 5 mmol·L^?1. With the increase of substrate concentration, the relative activation rate decreased in a definite glycine concentration. Michealis constant K_m of reaction decreased from 5.53 to 3.31 mmol·L^?1 and inhibition constant of product L‐ornithine K_p increased from 1.18 to 3.73 mmol·L^?1 when glycine concentration was 1 mmol·L^?1. For these reasons one possible activation mechanism of arginase by glycine was suggested that the activation effect results from the competition of glycine and arginine to enzyme activity position. When one or two of the activity positions of arginase are occupied by glycine, it is propitious for the enzyme to complex with substrate and obstruct L‐ornithine from combining with enzyme, and when all of the activity positions are occupied by glycine, the activation effect vanishs and the inhibition effect appears.     

Charged particle activation analysis of oxygen in fluoride and chalcogenide glasses used for fiber amplifiers

The proton activation analysis of oxygen was studied in fluoride and chalcogenide glasses used for fiber amplifiers. First, we studied the interfering nuclear reactions from glass matrices to determine the oxygen concentration in these glasses. By using substoichiometric separation for ¹⁸F after irradiation, we found that the oxygen concentration was 12 to 204 ppm in InF₃-based fluoride glass and 0.04% to 0.7% in chalcogenide glass containing sodium. We also discuss the relation between oxygen concentration and optical properties such as the infrared absorption spectrum and fluorescence lifetime.     

Concentration effects on laser-based δ18 O and δ2 H measurements and implications for the calibration of vapour measurements with liquid standards

Recently available isotope ratio infrared spectroscopy can directly measure the isotopic composition of atmospheric water vapour (δ¹⁸O, δ²H), overcoming one of the main limitations of isotope ratio mass spectrometry (IRMS) methods. Calibrating these gas‐phase instruments requires the vapourisation of liquid standards since primary standards in principle are liquids. Here we test the viability of calibrating a wavelength‐scanned cavity ring‐down spectroscopy (CRDS) instrument with vapourised liquid standards. We also quantify the dependency of the measured isotope values on the water concentration for a range of isotopic compositions. In both liquid and vapour samples, we found an increase in δ¹⁸O and δ²H with water vapour concentration. For δ¹⁸O, the slope of this increase was similar for liquid and vapour, with a slight positive relationship with sample δ‐value. For δ²H, we found diverging patterns for liquid and vapour samples, with no dependence on δ‐value for vapour, but a decreasing slope for liquid samples. We also quantified tubing memory effects to step changes in isotopic composition, avoiding concurrent changes in the water vapour concentration. Dekabon tubing exhibited much stronger, concentration‐dependent, memory effects for δ²H than stainless steel or perfluoroalkoxy (PFA) tubing. Direct vapour measurements with CRDS in a controlled experimental chamber agreed well with results obtained from vapour simultaneously collected in cold traps analysed by CRDS and IRMS. We conclude that vapour measurements can be calibrated reliably with liquid standards. We demonstrate how to take the concentration dependencies of the δ‐values into account. Copyright © 2010 John Wiley & Sons, Ltd.     

Study of 7Be activity concentration in the air of northern Spain

Time series analysis techniques have been applied to the study of the ⁷Be activity concentration in air, which was obtained by weekly collecting aerosols in filters in the north of Spain, and measuring them by gamma ray spectrometry. Between 2001 and 2009, a trend pattern is found. The cyclical component of this series is clearly influenced by the solar cycle (11 years period). Two kinds of seasonality were found in the time series: annual periodicity and variations with seasons of the year. The irregular component has also been studied but its contribution has been insignificant; one of its possible causes, rainfall, has been analysed and the conclusion is that the atmospheric concentration of ⁷Be is unaffected by rainfall. The contribution of ⁷Be presence in air to the total effective dose rate in air has also been studied, resulting negligible.     

Studies on the kinetics of ceric–thiourea-initiated aqueous polymerization of methyl methacrylate. I. Mechanistic features in moderately acid solution

The kinetics of the aqueous polymerization of methyl methacrylate by a ceric-thiourea initiator system in moderately acid solution (pH 2.15) was studied. The rate of polymerization was proportional to 0.41 power of ceric concentration, 0.32 power of thiourea concentration, and 1.18 power of monomer concentration. The degree of polymerization was smaller than expected from the rate of polymerization. Initiation efficiency was less than one. There was no evidence of any ceric ion termination in the concentration range of 2.50 × 10^?4–2.00 × 10^?3M studied. The results are explained in terms of partial primary radical termination; the principal mode of termination, however, was bimolecular.     

Kinetics of malachite green fading in water–ethanol–2‐propanol ternary mixtures

The rate constant of malachite green (MG⁺) alkaline fading was measured in water–ethanol–2‐propanol ternary mixtures. This reaction was studied under pseudo‐first‐order conditions at 283–303 K. It was observed that the observed reaction rate constants, k_obs, were increased in the presence of different weight percentages of ethanol and 2‐propanol. The fundamental rate constants of MG⁺ fading in these solutions were obtained by using the SESMORTAC model. In each series of experiments, the concentration of one alcohol was kept constant and the concentration of the second one was changed. It was observed that at the constant concentration of one alcohol and variable concentrations of the second one, with an increase in temperature, k₂ values decrease according to the trend of hydroxide ion nucleophilic parameter values and k₁ values increase. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 441–453, 2011     

Dielectric cure characterization of model elastomers

Isothermal dielectric properties of poly(dimethylsiloxane) (PDMS) networks during cure were studied at room temperature with emphasis on the effect of catalyst concentration. The frequency range employed was 10⁻¹ to 10⁵ Hz. The dielectric response is sensitive to a change in catalyst levels as this was evidenced by the change in the values of the logarithm of the loss factor log ϵ”. We attribute these changes to dipolar and ionic contributions. A profile of the cure reaction of model elastomers may readily be obtained by using a combination of microsensors and time-domain dielectric spectroscopy. The results obtained show that the catalyst concentration affects both crosslinking and chain extension reactions. However, for the typical catalyst concentration at which typical networks are prepared, the crosslinking reaction is the dominant effect.     

Polycondensation of cyclodextrins with epichlorohydrin. Influence of reaction conditions on the polymer structure

A series of water-soluble polymers was synthesized by polycondensation of cyclodextrin with epichlorohydrin under basic conditions. We studied their molecular distribution as a function of molar ratios of reactants. NaOH concentration showed that very high molecular averages (Mw > 10⁶) can be obtained. The substitution patterns were determined by ¹³C NMR analysis and standard methylation analysis of polysaccharides. The formation of side chains and bridges consisting of sequences of poly(2-hydroxypropyl)ether units were demonstrated by electrospray ionization mass spectrometry and gas liquid chromatography-mass spectrometry. The predominant position of substitution depends on the NaOH concentration.     

Fluorimetry and differential scanning calorimetry analysis of ionomers with low Eu3+ contents

Fluorimetry and differential scanning calorimetry have been used to characterize ionomers that were synthesized by copolymerization of methyl methacrylate, methacrylic acid, and europium methacrylate (EMA). Under excitation of UV light at 375 nm no self-quenching was found in fluorescence of EMA-containing ionomers at 615 nm within the Eu³⁺ concentration range of 1.6 × 10⁻² to 11.49 × 10⁻² mol %, which means that the distance between two Eu³⁺ ions is larger than 50 Å. In the same concentration range self-quenching took place in europium octanoate (EOA)-containing ionomers in which EOA was doped as an additive. Only one T_g was found for both kinds of polymers within the concentration range of Eu³⁺ ions. For all ion contents studied, T_g values were essentially independent of ion content and values were slightly higher for the EMA containing ionomers. © 1997 John Wiley & Sons, Inc.     

The influence of the nature of background anions on the buffer capacity of glycine-containing electrolytes for nickel electroplating

The buffer properties of acetate, sulfate, and chloride glycine-containing electrolytes for nickel electroplating were studied. Various forms of the amino acid and background anions were shown to act in solution as two buffer systems related by competitive complex formation. The buffer capacity of a solution was then the result of the joint action of these systems. The contribution of each of them was determined by its absolute concentration in solution on the one hand and changes in this concentration caused by the addition of H⁺ or OH^? ions on the other.     

Studies of lithium and sodium complexation by silicon podand solvents

The complex formation of lithium and sodium ions with silicon podand solvents: phenyl-tris(1,4-dioxapentyl) silane (PhSi23) and ethyl-tris(1,4-dioxapentyl) silane (EtSi23) has been studied by FTIR, ¹H-, ¹³C-, ⁷Li- and ²³Na NMR. The far FTIR spectra show that the Li⁺ cations fluctuate very fast whereas Na⁺ cations are still localised between the oxygen atoms of the oxaalkyl chains. The ⁷Li NMR spectra prove that one Li⁺ cation can be coordinated not only by one but also two silicon podand molecules. The concentration dependence of the molar conductivity of LiClO₄ in the podand solvents indicates charge transfer between ion clusters.     

The influence of serum fatty acid binding proteins on arachidonic acid uptake by macrophages

The role of serum fatty acid binding proteins (FABPs) in arachidonic acid (AA) uptake by murine peritoneal macrophages has been studied. The kinetics of [³H]arachidonic acid uptake by the cells was investigated over a wide range of AA concentration (10⁻¹⁰–10⁻⁵ M). It was shown that these putative fatty acid transporters dramatically change the uptake processes. In the presence of FABPs, the time-course curves of AA uptake exhibited two distinct periods: one with a rapid AA uptake during the first hour with an equilibrium in 1–2.5 h and another with an equilibrium reached in 20 h, whereas in the absence of FABPs the uptake curves were smooth without kinks and with the equilibrium reached in 10 h. In addition, it was shown that the amount of incorporated AA was linearly dependent on the concentration of AA over the range of 10⁻¹⁰–10⁻⁶ M in the presence of serum FABPs and 10⁻¹⁰–10⁻⁷ M in their absence. We assume that the changes in the character of AA uptake by macrophages in the presence of FABP soccur due to the interaction of FABPs with the cell plasma membrane.     

Analysis of 99Tc in the radioactive liquid waste after extraction into suitable solvent

⁹⁹Tc is one of the long lived fission product with high fission yield. From radioactive waste management point of view it is very much essential to evaluate the concentration of technetium in the radioactive liquid waste in order to finalise the treatment process to extract/isolate it from the stream which is discharged to the environment. For the estimation of ⁹⁹Tc in the radioactive liquid waste stream, extraction of the stable complex of technetium-tetraphenyl arsonium chloride (TPAC) into chloroform followed by beta counting was studied. Various parameters like pH, time of equilibration, concentration of TPAC in chloroform, use of other solvent for extraction as well as interference of various other radionuclides present in the waste were also studied. The radioactive liquid waste being handled in plant contains high concentrations of salts in the form of sodium nitrate. Hence effect of salt concentration on the percentage extraction was also evaluated. The extraction behavior does not dependent on change in the pH of the solution. Almost 99.5% extraction was observed in the pH range of 1?C13.0. High concentration of salt is affecting the extraction. However, this can be taken care by diluting the radioactive waste. It takes almost 90?min time for maximum extraction. Presence of radionuclides like ¹³⁷Cs, ⁹⁰Sr are not interfering the extraction of ⁹⁹Tc. However, ¹⁰⁶Ru is getting slightly extracted along with ⁹⁹Tc. The error due to ¹⁰⁶Ru can be eliminated by taking gamma spectrum and deducting the activity from the total beta activity to get ⁹⁹Tc activity. Nitrobenzene can be used for extraction of Tc?CTPAC complex in place of chloroform.     

Portable formaldehyde monitoring device using porous glass sensor and its applications in indoor air quality studies

We have developed a portable device for formaldehyde monitoring with both high sensitivity and high temporal resolution, and carried out indoor air formaldehyde concentration analysis. The absorbance difference of the sensor element was measured in the monitoring device at regular intervals of, for example, one hour or 30 min, and the result was converted into the formaldehyde concentration. This was possible because we found that the lutidine derivative that was formed as a yellow product of the reaction between 1-phenyl-1,3-butandione and formaldehyde was stable in porous glass for at least six months. We estimated the reaction rate and to be 0.049 min⁻¹ and the reaction occurred quickly enough for us to monitor hourly changes in the formaldehyde concentration. The detection limit was 5 μg m⁻³ h. We achieved hourly formaldehyde monitoring using the developed device under several indoor conditions, and estimated the air exchange rate and formaldehyde adsorption rate, which we adopted as a new term in the mass balance equation for formaldehyde, in one office.     

Self-association of caffeine in aqueous solution. Study of dilute solutions by normal and second derivative UV absorption spectroscopy.

The concentration dependence of the spectral parameters of caffeine bands at ∼205 and 273 nm has been studied in aqueous solution by normal and second derivative spectroscopy. The concentration range was 5 x 10⁻⁶ − 5 x 10⁻³ M and thirty-five different concentrations were used.Discontinuities in parameter variation of these two bands at ∼7.5 x 10⁻⁵, ∼2 x 10⁻⁴, and ∼1 x 10⁻³M were observed as concentration was increased. These “limiting” concentrations define three quite differenciated hyper- or hipochromic effects: the first one can be explained as caffeine-water molecule interaction and the second and third as dimer and (dimer + polymer) stacking, respectively. Apparent self-association constants using the isodesmic model have been obtained K= 160 M⁻¹ (for the second hypochromic effect) and K= 13.6 M⁻¹ (for the third hypochromic effect), for the 273 nm band.It is noteworthy that the three “limiting” concentrations coincide with changes in DNA-caffeine interaction modes (H. Lang , 1976) and biological activity (I.B. Syed , 1976).     

Oxidaiton of tin/II/ in air-kept hydrochloric acid solutions

An air-storage stability of tin/II/ chloride solution was studied by voltammetric and spectrophotometric methods. The chosen concentration range was due to the problems of the kits preparation for a^99mTc generator. The rate of oxidation of tin/II/ in the range of 0.04–12.5 mg.ml^–1 was shown to decrease with an increase in tin concentration. According to the obtained results one can determine maximal storage time for the correct practical use.     

Sensitive Anodic Stripping Voltammetric Copper Ions Determination Performed in Double Deposition and Double Stripping Steps System for Real Water Samples Analysis

The article reports on utilization of double deposition and stripping steps for increasing sensitivity of Cu(II) determination by anodic stripping voltammetry (ASV) at two lead film working electrodes. A significant preconcentration of copper was achieved thanks to utilization of a simple design of four electrodes system that gives possibility to perform one measurement cycle consisting of two deposition and two stripping steps. Due to the fact that deposition step is doubled, the concentration of Pb(II) needed to lead film electrodes formation was significantly reduced as compared to traditional procedures using three electrodes system. The analytical procedure of Cu(II) determination was optimized. The experimental factors: supporting electrolyte's pH and its concentration, lead ions concentration, potential and time of deposition at both working electrodes were studied. The Cu(II) peak current was linearly dependent on its concentration from 5×10^?10 to 2×10^?8 mol L^?1 (deposition time of 270 and 160 s at the first and the second working electrode, respectively). The obtained detection limit for copper ions determination was 2.1×10^?10 mol L^?1. The described procedure was validated by analysis of two water certified reference materials. The described procedure was also utilized for real water sample analysis.