Volume 11, Issue 3

Abstract By coupling a matrix assisted laser desorption source to an electric beam deflection setup, we have measured the permanent electric dipole moment of the isolated para-fluroaniline PFAN (FC6H4NH2) molecule in the ground state. This measurement of the electric dipole of an isolated push-pull molecule is unique. The experimental value is compared to two different calculations and the structure of the system is discussed. Graphical abstract

Abstract The effect of the surface treatment by H3PW12O40 solution on electrochemical properties of the LaCo4.8Bi0.2 alloy was investigated. A significant increase of hydrogen absorption and a distinct increase of exchange current density was obtained for LaCo4.8Bi0.2 alloy activated with tungstophosphoric acid. Potentiokinetic polarization curves show that the anodic currents increase with the amount of absorbing hydrogen. Graphical abstract

Abstract Separation of enantiomers represents an extremely important task in the field of analytical chemistry. This paper contributes to the field of the on-line preconcentration of enantiomers by developing a novel setup based on the electrokinetic accumulation of ketoprofen enantiomers on the pH boundary followed by enantioselective mobilization by a mixture of SDS, sulfated-β-cyclodextrin (S-β-CD), and trimethyl-β-cyclodextrin (TM-β-CD). Under the best conditions, where the injection electrolyte was composed of 50 mmol L−1 borate/NaOH pH 9.5 with 60% (v/v) methanol, the background electrolyte contained 50 mmol L−1 phosphate/NaOH pH 2.5, and the mobilization electrolyte consisted of 50 mmol L−1 phosphate/NaOH pH 2.5 with 4.0% (w/v) S-β-CD, 0.5% (w/v) TM-β-CD, and 20 mmol L−1 SDS, the determination of nanomolar concentration levels of ketoprofen enantiomers was successful by using micellar electrokinetic chromatography with a common UV detection. LODs were 2.5 nmol L−1 and 3.4 nmol L−1, which represent enhancement factors of 9921 and 8529, respectively. The method was also applied to the determination of ketoprofen enantiomers in waste water samples by using simple filtration as a clean-up step. Here, the recovery of ketoprofen enantiomers was 91% at the concentration level of 5×10−9 mol L−1. Graphical abstract

Abstract Selective separation of cadmium(II) on a macrocycle immobilized solid phase extraction (SPE) system namely AnaLig Cd-01, and commonly known as molecular recognition technology (MRT) gel, have been examined. The MRT-SPE able to retain the cadmium from the metal-affluent aqueous matrix at the pH range of 2 to 8, and the captured species can be recovered via elution with 1 and 6 M HNO3. Besides the effects of solution pH and eluent concentration, the impacts of sample loading flow rates and coexisting matrix ions were also investigated and optimized. The Cd(II) retention capacity of the MRT-SPE was 0.26 mmol g-1, and it can be reused for more than 100 loading and elution cycles. The Cd(II) recovery attained from the metal-spiked natural waters was satisfactory (95.3–98.1%). However, the Cd(II) retention ability of the MRT-SPE was significantly decreased when excess of chelant remain in the aqueous waste matrix. Graphical abstract

Abstract The quantitative real-time polymerase chain reaction (qPCR) is a sensitive technique for examining the influence of erythropoietin (Epo) on gene expression. A critical and fundamental step for data analysis is the selection of and normalization to the optimal reference gene(s). We identified appropriate reference gene(s) among 32 genes during chronic recombinant human Epo (rHuEpo) treatment of SH-SY5Y cells using TaqMan human Express Endogenous Control Plate. Expression stability of the selected reference gene (RPLP) was retested with qPCR, together with two commonly used reference genes (GAPDH, ACTB) and six genes of interest (EPOR, EPO, STAT5B, STAT5A, JUN, AKT). In PC12 cells, three commonly used reference genes (Gapdh, CycA and Ywhaz) and seven genes of interest (EpoR, Epo, Stat5b, Stat5a, Jun, Akt, Fos) were evaluated. For the evaluation of expression stability, geNorm, NormFinder and BestKeeper software were used. All three gave similar results. We demonstrated that among the housekeeping genes, RPLP in SH-SY5Y and CycA and Ywhaz in PC12 are the most stable genes. Additionally, we showed that normalization with GAPDH gave misleading results compared to normalization with geNorm. In conclusion, selection of the appropriate normalization gene(s) is crucial for correct interpretation of rHuEpo treatment results. Graphical abstract

Abstract In this work, FeOOH arrays were obtained using two different magnetic cations. The nanoparticles were grouped into a package having different orientations through the van der Waals interaction with the magnetic cations. With Fe2+, the FeOOH nanoparticles have a rod shape with a 30-nm diameter and approximately 1-micron length, and are aligned in a star structure. With Co2+, a somatoidal shape was observed, with 20-nm diameter and 150-nm length and a pathway structure to the array. The chemical synthesis method was used to obtain the nanoarrays. The morphology and the average size of the nanorods and nanowires were determined using Field Emission Scanning Electron Microscopy (FESEM). Fourier Transform Infrared Spectroscopy (FTIR) was used to study the interaction between the nanorods and the cobalt ions. The phases of the material were identified using X-ray Diffraction. Graphical abstract

Abstract The present study is a continuation of our previous investigations on the ZnO-TiO2 system. By applying different sol-gel methods we proved that the type of precursor and the order of adding the components influence the microstructure of the final product. This study focuses on the combustion sol-gel synthesis and photocatalytic properties of nanosized (∼7-20 nm) ZnO-TiO2 powders. The photocatalytic tests were performed toward two model organic dyes, Malachite Green and Reactive Black 5, in the UV and Vis region. For synthesis of ZnO/TiO2 powders, different precursors such as Zn(NO3)2·6H2O, Zn(CH3COO)2·2H2O, Ti(OC2H5)4 and Ti(OC4H9)4 were used. During the combustion process various phases (ZnO, TiO2 — anatase and rutile, ZnTiO3) were obtained. The structure and morphology of the resulting particles were characterized by XRD and SEM analysis. All samples exhibited a good photocatalytic activity in both UV and Vis regions. Graphical abstract

Abstract The CORAL software (http://www.insilico.eu/coral/) has been examined as a tool for modeling anti-HIV-1 activity by quantitative structure — activity relationships (QSAR) for three different sets: (i) TIBO derivatives (n=82) (ii) anti-HIV-1 activity of 2-amino-6-arylsulfonylbenzonitriles and their congeners (n=64), and (iii) the measured binding affinity for fullerene-based HIV-1 PR inhibitors (n=48). A new global invariant ATOMPAIR of the molecular structure which can be calculated with the simplified molecular input line entry system (SMILES) was studied. The ATOMPAIR is an indicator of the joint presence of pairs of chemical elements (F, Cl, Br, N, O, S, and P) and three types of bonds (double covalent bond, triple covalent bond, and stereo chemical bond). Six random splits into sub-training, calibration, and test set were examined for each set. For the three aforementioned sets, the use of ATOMPAIR in the modeling process improves the predictive potential of the models for six random splits. Graphical abstract

Abstract Detailed investigations on the possibility for determination of the oxygen stoichiometry in YBa2Cu3Oy superconducting samples by measuring the absorbance of the colored Co(III)-EDTA and Cu(II)-EDTA complexes in one solution have been performed. The absorptivity of the complexes at pH 2.5 and 4.9 as well as Beer’s law have been studied. The content of the solution for the sample dissolving has been established. The stoichiometry of the oxidation-reduction reaction between Cu(III) from the sample and Co(II) in the solution has been proved. The possibility to dissolve the sample in air has been tested. As a result a simple and rapid spectrophotometric method for the determination of the δ non-stoichiometric oxygen coefficient in YBa2Cu3O6.5+δ samples has been developed without precise measurement of the sample mass. The standard deviation of the δ- and y-coefficient results is 0.017. The reproducibility of the y-values in relative units (sr ) is 0.2%. The accuracy of the results has been confirmed by the method, which is based on the absorbance measurement of the I 3−-starch compound. Graphical abstract

The flash points of three organic binary mixtures containing alcohols were measured in the present work. The experimental data was obtained using the Pensky-Martens closed cup tester. The experimental data were compared with the values calculated by the Liaw model. Activity coefficients were calculated by the Wilson equation and NRTL equation. The accuracy of predicted flash point values is dependent on the thermodynamic model used for activity coefficient.

Abstract An efficient method based on dispersive liquid-liquid microextraction coupled with micellar electrokinetic chromatography has been developed for determination of three phenoxyacid herbicides (PAs) of 2,4-dichlorophenoxybutyric acid (2,4-DB), dicamba and 2,4-dichlorophenoxyacetic acid (2,4-D), in environmental water samples. The types and volumes of extracting and dispersing solvents, ionic strength, extraction and centrifugation time and centrifugation speed were investigated. Successful separation of the three PAs was achieved within 7 min, by using the background electrolyte solution consisting of 10 mmol L−1 sodium tetraborate, 25 mmol L−1 sodium dodecyl sulfate and 15% (v/v) methanol, at pH 9.75. Excellent analytical performances were attained, such as good linear relationships (R ≥0.9993) between peak area and concentration for each PAs from 10–1000 ng mL−1, limits of detection of 1.56–1.91 ng mL−1, and intra-day precisions at two spiked levels in terms of migration time and peak area within the range of 0.22–0.42% and 3.88–6.39%, respectively. Enrichment factors of 2,4-DB, dicamba and 2,4-D were 180, 151 and 216, respectively. The method recoveries obtained at fortified 20.0, 50.0 and 100.0 ng mL−1 for lake, river and reservoir water samples varied from 67.91 to 119.07% with the relative standard deviation of 1.47–6.89%. Graphical abstract

Abstract The analysis of reactivity indices suggests the polar nature of the [2+3] cycloaddition of a-phenylnitroethene to (Z)-C,N-diphenylnitrone. Similar conclusions can be drawn from the investigation of the reaction pathways using the B3LYP/6-31g(d) algorithm. This shows that the cycloaddition mechanism depends on the polarity of the reaction medium. A one-step mechanism is followed in the gas phase and toluene in all the theoretically possible pathways. In more polar media (nitromethane, water), a zwitterionic, two-step rather than a one-step mechanism occurs in the pathway leading to 3,4-trans-2,3,5-triphenyl-4-nitroisoxazolidine. Graphical abstract

Abstract Carbon nanotubes paste electrodes (CNTPEs) in combination with adsorptive transfer stripping voltammetry are shown to be very suitable for the determination of calf thymus double-stranded DNA (dsDNA). The performance of three types of multi-walled carbon nanotubes paste electrodes (MWCNTPEs) is investigated. The effects of surface pre-treatment and accumulation conditions on the adsorption and electrooxidation of the dsDNA at MWCNTPEs are also described. The results indicate that the electroactivity inherent to carbon nanotubes/paste electrodes allows a large enhancement of the guanine oxidation signal compared to that obtained at the conventional carbon paste electrodes (CPEs). Moreover, the extent of the enhancement dependents on the type of MWCNTs incorporated into the paste. Based on the signal of guanine, under optimal conditions, very low levels of dsDNA can be detected following short accumulation times for all three types of MWCNTPEs (MWCNTPE1, MWCNTPE2, MWCNTPE3), with detection limits of 2.64 mg L−1, 2.02 mg L−1 and 1.46 mg L−1, respectively. Additionally, the dsDNA isolated from rat liver tissues is determined by use of the previously mentioned MWCNTPEs. Graphical abstract

Abstract The interaction between Mg2+ and a phosphatidylcholine (lecithin, L) monolayer at the air/water interface was investigated. Surface tension measurements (Langmuir method) of phosphatidylcholine monolayers as a function of Mg2+ concentration were carried out at 22°C using a Teflon trough and a Nima 9000 tensiometer. Interactions between phosphatidylcholine and Mg2+ result in significant deviations from additivity. An equilibrium theory was developed to obtain the stability constants and areas occupied by one molecule of LMg+ and L2Mg. The stability constants were K 1 = 9.95×102 m2 mol−1 and K 2 = 3.87×104 m2 mol−1. The area occupied by LMg+ is 77 Å2 molecule−1, while that occupied by L2Mg is 109 Å2 molecule−1. The Gibbs free energies of complexation for LMg+ and L2Mg are −16.91 ± 0.51 and −25.88 ± 0.76 kJ mol−1. Graphical abstract

Abstract Morphine (1) and codeine (2) are two representatives of medically important, frequently used natural opiates, therefore the exploration of their metabolic pathways and the exact characterization of the metabolites are main targets of their pharmacological studies. These morphinans also play a crucial role in drug abuse; therefore, the analysis and preparation of the metabolites for identification and quantitation in human samples are considered important aims. In order to allow the in-depth analysis of metabolites derived from the oxidative pathways through morphinone (3) and codeinone (4), synthetic procedures have been elaborated for the gram-scale preparation of glutathione and N-acetylcysteine adducts. Primary pharmacological studies revealed the inactive nature of these metabolites in opioid receptor binding tests. Graphical abstract

Abstract In this paper we present the synthesis of two composite membranes with sulfonated polyether etherketone as support polymer and as conductive polymers: polyaniline and poly(p-phenylenediamine) — which has a similar structure with polyaniline. The support membranes were obtained by the phase inversion process, the conductive polymers were added by in situ polymerization into the membrane pores, and to increase the conductive properties they were doped with polystyrene sulfonic acid. The synthesized membranes were characterized by FT-IR spectroscopy, SEM, EDAX and electrochemical impedance spectroscopy. Graphical abstract

Abstract New polymer hydrogels based on partially phosphorylated poly(vinyl alcohol) (PVA/Phosphoester) have been prepared. Fourier transform infrared spectroscopy (FT-IR) was employed to confirm PVA/Phosphoester formation. Contact angle measurements were performed to evaluate the surface characteristics of the hydrogels. The PVA/Phosphoester hydrogels were co-networked with Chondroitin sulfate (CS) in various ratios by chemical crosslinking. The synthetic-natural mixed resulted semi-IPN hydrogels were structurally and morphologically investigated by ATR — FT-IR spectroscopy and scanning electron microscopy, respectively. The swelling behavior and dynamic moisture sorption capacity of the PVA/Phosphoester (p-methyl-phenyl phosphonic dichloride) (P3)-CS semi-IPN hydrogels were followed. It was found that the performance of the semi-IPN hydrogels was influenced by the CS. By kinetic studies, it has been shown that the swelling processes occurred by an anomalous transport mechanism. Graphical abstract

Abstract Experimentally-known sulfur-sulfur distances shorter than the sum of van der Waals radii and involving two chemically-identical sulfur atoms are examined at several levels of theory (BP86/6-31G** to CCSD(T)/6-311+G**). None of the theoretical methods predict an attractive interaction from an energetic point of view, even though molecular orbitals stretching between the two sulfur atoms have been identified. Most likely, if there is indeed an attractive interaction force between chemically identical sulfur atoms, its value is comparable to the accuracy of the methods employed here — implying an attractive interaction below 1 kcal/mol. The investigation includes some simple models of 1,6,12,17-tetrathiacyclodocosa-2,4,13,15-tetrayne which was previously shown to have an S—S interaction involving two chemically-identical atoms. Attractive interactions calculated for these latter models are shown to arise from S—HC weak bonding, with the S—S interaction being again repulsive. Graphical abstract

Abstract Four photocatalyst samples, prepared from beech sawdust, were synthesized by an original method, combining pyrolysis and impregnation — two of them: TiO2 + activated carbon and other two — only activated carbon. The pyrolysis process has been carried out at two different temperatures — 680°C and 830°C. The prepared samples were characterized by a series of methods — XRD, BET, SEM and DTA/TG. The most important result was achieving visible light photocatalytic activity with an azo dye pollutant for both materials. The TiO2/AC-680°C sample demonstrated higher activity under visible light illumination than the TiO2/AC-830°C sample. The visible light activity was attributed to the active carbon component in the composite materials, which was evidenced by the photocatalytic tests with bare carbon (without any TiO2) manifesting visible light activity. The AC-680°C carbon was superior to the AC-830°C under visible illumination probably due to its higher specific surface area and porous texture. UV-light testing of the photocatalytic activity revealed that the TiO2/AC-680°C sample was higher than that of the TiO2/AC-830°C under polychromatic UV-A illumination (320–400 nm with a maximum at l = 365 nm). The TiO2/AC-680°C sample was also more efficient with the monochromatic UV-C illumination (l = 254 nm). Graphical abstract