Structure of starch-bentonite gels

Mixed gels of starch and bentonite are investigated in the interval 0.056–0.089 of total solids/water ratio and 0-100% starch in the solids. The bentonite was a sodium calcium bentonite with a Na/Ca ratio of 1.76. In water it forms gels consisting of a network of band-type structures. Starch forms gels through hydrogen bonds between granules and/or amylose and amylopectin present on the external surfaces of granules and/or in fully stretched form. Mixed gels of bentonite and starch were obtained by adding corn starch granules to the already formed bentonite gels and heating the mixture above the Kofler gelatinization temperature. Amylose and amylopectin were adsorbed on strands of band-type structures of mont-morillonite lamellae. Starch gellation, e.g. diffusion of amylose out of the granule, was facilitated in the presence of bentonite. On the other hand, the presence of starch favored delamination of the montmorillonite particle into thinner lamellae. Maximum gelatinization and polymer adsorption were observed for gels with 20% starch and 80% bentonite. Montmorillonite networks formed the continuous phase for 0-80% starch. At higher starch concentrations, montmorillonite flakes were dispersed within the polymer network. Increase in the water content of the gels caused segregation of the bentonite and starch.     

Measurement of L&agr; and Lß X-ray fluorescence cross sections in Er, Ta, W and Au by 16.896–59.543 keV photons

La and Lb X-ray fluorescence cross sections in Er, Ta, W and Au at excitation energies of 16.896, 22.581, 25.770, 32.890, 38.184, 43.949, 50.214 and 59.5 keV were investigated. Measurements were made using a low energy Si(Li) detector coupled to a model 4096 computerized multi-channel analyser. The experimental results were compared with the theoretically calculated values of L X-rays fluorescence cross sections and other experimental results. Good agreement was observed between experimental and theoretical values.     

Raman Micro-Spectroscopy of Dental Pulp Stem Cells: An Approach to Monitor the Effects of Cone Beam Computed Tomography Low-Dose Ionizing Radiation

The objective of this study was to determine the molecular and biochemical changes in dental pulp stem cells (DPSCs) due to consecutive low-dose ionizing radiation exposures using label-free Raman micro-spectroscopy (RMS). Ionizing radiation produces biological damage leading to health effects of varying severity. The effects and subsequent health implications caused by exposure to low-dose radiation, such as diagnostic exposure, remain ambiguous. We identified Raman biomarkers characteristic to low-dose cone beam computed tomography (CBCT) irradiation of the DPSCs. The biomarkers were monitored inside the cells using the relative intensity distribution of the 785 and 1734?cm^?1 bands. The control cells presented a higher relative intensity of the nucleic acid specific Raman bands, whereas the irradiated cells revealed an increased intensity of the lipid-induced bands. The results obtained in this study demonstrate the capability of RMS for the detection of cell response to diagnostic radiation dose levels. This may indicate the potential of the technique for future applications such as monitoring the radiation responses in pediatric patients suffering repeated radiological exposures.     

Crystal structure,spectroscopic characterization,DFT computations and molecular docking study of a synthesized Zn(II) complex

The Zn(II) complex, dichloro[N-hydroxy-1,1-di(2-pyridinyl)methanimine]zinc(II), was synthesized from the reaction between ZnCl₂ and di-2-pyridylketone oxime. The structural and spectral characterizations were performed by using single crystal X-ray diffraction, FT-IR, Laser-Raman, NMR and UV–Vis spectroscopic techniques. To support experimental evidences, computational results were obtained with the DFT/B3LYP method using the 6-311++G(d,p)+LanL2DZ mixed basis set. Theoretical analyses of some structural and spectroscopic results of effects of intermolecular Cl···H interactions in the crystal packing of the Zn(II) complex were investigated with the mentioned computational level. The non-bonding interactions in the experimental crystal packing of the complex were examined by Hirshfeld surface analysis. The HOMO and LUMO analyses were used for investigation of electronic transitions obtained with UV–Vis spectroscopy. NBO analyses were used to investigate the hyperconjugation interactions between donor and acceptor groups, coordination environment, electronic configuration and electron numbers of the Zn(II) metal ion and the natural atomic charges of the complex. The nucleophilic and electrophilic reactive sites of the complex were studied by MEP surface analysis. The static polarizabilities (α) and static hyperpolarizabilities (β) were analyzed theoretically to characterize NLO profile of the complex. The interaction with A-DNA (PDB ID: 1ZF6) of the Zn(II) complex was investigated with a molecular docking study.     

Electroanalysis of Bisphenols A,F, and Z Using Graphene Based Stochastic Microsensors

Two stochastic microsensors based on immobilization of the complex between protoporphyrin IX and cobalt on nanographene paste and on the reduced graphene oxide paste were proposed for the simultaneous identification and quantification of bisphenols A (BPA), F (BPF) and Z (BPZ) from water samples. The signatures obtained for the BPA, BPF, and BFZ when both stochastic microsensors were used shown that the microsensors can be used for the discrimination between the three bisphenols in water samples. Very low limits of determination were obtained for the three bisphenols: 1fmol/L for BPA and BPF when the microsensor based on the immobilization of the complex between protoporphyrin IX and cobalt on nanographene paste was used, and 10fmol/L for BPZ when the microsensor based on the immobilization of the complex between protoporphyrin IX and cobalt on reduced graphene oxide paste was used. The linear concentration ranges covered by the proposed stochastic microsensors were: between 10^?15 and 10^?5 mol/L for BPA, between 10^?15 and 10^?7 mol/L for BPF, and between 10^?13 and 10^?10 mol/L for BPZ. The recoveries of the bisphenols in water samples were higher than 99.50 %, with RSD values lower than 1.00 %.     

Polycyclic aromatic hydrocarbon and ionic compositions of atmospheric bulk deposition samples at a national park under the influence of intense barbecue smoke

The main aim of this study was to present the effects of barbecue smoke on a small-scale environment, a national park under the influence of intense barbecue smoke, and to scientifically support the sustainable usage of the park. Twelve-weekly bulk deposition samples were collected directly at the barbecuing area, and the samples were analysed for 16 US EPA’s priority PAH compounds and major ions. The mean concentrations of the individual PAHs in the bulk deposition samples ranged from 11.8 ng L^?1 (Ane) to 1085 ± 581 ng L^?1 (IcdP). The most frequently observed PAH compounds in the bulk deposition samples were Np, Anp, Flr, Phe, An, Flu, BkF, BaP and IcdP. The mean total PAH deposition fluxes were determined as 3.6 ± 5.6 µg m^?2 day^?1. The chloride, potassium and the sulphate fluxes were determined as 145.2 ± 267.8 µg m^?2 day^?1, 182.9 ± 291.9 µg m^?2 day^?1, and 111.9 ± 65.9 µg m^?2 day^?1, respectively. Dominant ions in the bulk deposition samples were potassium ion, chloride and sulphate which addressed as the fingerprint of barbecue grilling.     

Phenolic compounds from the aerial parts of Clematis viticella L. and their in vitro anti-inflammatory activities*

Phytochemical investigations on the EtOH extract of Clematis viticella led to the isolation of six flavonoid glycosides, isoorientin (1), isoorientin 3′-O-methyl ether (2), quercetin 7-O-α-L-rhamnopyranoside (3), quercetin 3,7-di-O-α-L-rhamnopyranoside (4), manghaslin (5) and chrysoeriol 7-O-β-D-glucopyranoside (6), one phenylethanol derivative, hydroxytyrosol (7), along with three phenolic acids, caffeic acid (8), (E)-p-coumaric acid (9) and p-hydroxybenzoic acid (10). The structures of the isolates were elucidated on the basis of NMR and HR-MS data. All compounds were isolated from C. viticella for the first time. Compounds 7 and 8 showed significant anti-inflammatory activity at 100 μM by reducing the release of NO in LPS-stimulated macrophages comparable to positive control indomethacin. Compounds 3 and 7 exhibited anti-inflammatory activity through lowering the levels of TNF-α while 1, 3 and 5 decreased the levels of neopterin better than the positive controls.     

Investigations for Modification of Polyacrylamide-Bentonite by Phytic Acid and its Usability in Fe3+, Zn2+ and UO2 2+ Adsorption

Composite of polyacrylamide-bentonite (PAA-B) was prepared by direct polymerisation of PAA in a suspension of bentonite (B). Adsorption and thermodynamic features of phytic acid (Phy) adsorption onto B, PAA and PAA-B, and those of Fe³⁺, Zn²⁺, UO₂ ²⁺ adsorption onto PAA-B and its modification by Phy (PAA-B-Phy) have been investigated. The reusability, storagability, ion selectivity and recoverability of sorbed ions with 1 M HCl have also been considered.The chemical and physical structure of adsorbents has been characterised by means of FT-IR and XRD. All adsorption isotherms for Phy and the ions were L-type of the Giles classification except, the one which is S type for adsorption of Phy onto PAA. The maximum adsorption capacities for the ions adsorbed were in order of UO₂ ²⁺ > Fe³⁺ > Zn²⁺ for PAA-B and Zn²⁺ > Fe³⁺ > UO₂ ²⁺ for PAA-B-Phy. Langmuir equilibrium constants for the adsorption of ions onto PAA-B-Phy were significantly higher than those found for PAA-B; the magnitude of increase for UO₂ ²⁺ was about 100. The thermodynamic parameters indicated that adsorption reactions are spontaneous in terms of adsorption free enthalpy.The chemical structure of PAA-B-Phy was not changed at the end of the studies of reusability and storagability. The composite was selective for UO₂ ²⁺ of the ions of interest.The composite of PAA-B and its modification by Phy have been used for the first time in this investigation. It is proposed that the composites can be practically used in the investigations and applications of adsorption.     

Radioiodination and preliminary biological tests of aniline-mustard and its glucuronide conjugate as a potential anticancer prodrug

Aniline-mustard and its glucuronide conjugate were radioiodinated with ¹³¹I. The preliminary dynamic tests were carried out on rabbits. The scintigrams showed clearly that the glucuronide conjugate of aniline-mustard was very quickly cleared from the metabolism, accumulating in the bladder in about 15 minutes. The clearance time of radioiodinated aniline-mustard-glucuronide was considerably longer (about 45 min.). The results obtained from the biodistributional studies have represented interesting differences between the metabolic details of radioiodinated compounds, and indicated that the glucuronide conjugate of aniline-mustard may be a promising radioiodinated prodrug, if verification of its selective accumulation in some kinds of tumor cells can be obtained.     

Enamines of 1,3-dimethylbarbiturates and their symmetrical palladium(II) complexes: synthesis,characterization and biological activity

Transition Metal Chemistry - Three 1,3-dimethylbarbiturate-enamine derivatives and their symmetrical palladium(II) complexes were prepared and characterized by spectroscopic methods. In addition,...