Optimization of the direct LSC method for determination of biogenic component in liquids by applying 14C

Journal of Radioanalytical and Nuclear Chemistry - Determination of fraction of biogenic component in liquid fuels by a direct radiocarbon measurement in liquid scintillation counter (direct-LSC...     

Quality Assessment of Two Spectrophotometric Procedures for Polyphenol Determination and Application in Moltkia petraea Species

A comparison study of quality of two spectrophotometric procedures: Schneider’s (T‐Sch) and 4‐aminoantipyrine (T‐AAP) procedures for total polyphenols determination was carried out using informative prevalidation strategy. Good quality of the measurements at the lower analyte level, excellent resolution of signals, homogenous data material, ideal linear calibration and analytical evaluation functions, very low limit of quantitation (0.13 μg/mL), and high precision (from ±0.60 % to ±3.43 %) and accuracy (from ?4.26 % to +4.00 %) confirmed the high quality of the T‐Sch procedure. Although favorable performance characteristics of T‐AAP procedure were obtained, the signal resolution, sensitivity, precision and accuracy are somewhat lower than in T‐Sch procedure. Both prevalidated procedures were successfully applied to determine total polyphenols in leaves, stems, and flowers in three populations of endemic Illyric? Balkan species Moltkia petraea (Tratt.) Griseb. growing in Croatia. Total concentrations of polyphenols obtained by T‐Sch procedure in all plant organs of all populations were somewhat lower than determined by T‐AAP procedure. However, the relative abundance of polyphenols obtained by both methods is the same. Prevalidation results demonstrated the reliability of the T‐AAP and T‐Sch procedures as valuable tools in polyphenols analysis and their application provided new information regarding phytochemical characterization of endemic M. petraea.     

Evaluation of DNA-Damaging Effects Induced by Different Tanning Agents Used in the Processing of Natural Leather—Pilot Study on HepG2 Cell Line

For a long time, the production and processing of cowhide was based on the use of chrome tanning. However, the growing problem with chromium waste and its negative impact on human health and the environment prompted the search for more environmentally friendly processes such as vegetable tanning or aldehyde tanning. In the present study, we investigated the DNA-damaging effects induced in HepG2 cells after 24 h exposure to leather samples (cut into 1 × 1 cm² rectangles) processed with different tanning agents. Our main objective was to determine which tanning procedure resulted in the highest DNA instability. The extent of treatment-induced DNA damage was determined using the alkaline comet assay. All tanning processes used in leather processing caused primary DNA damage in HepG2 cells compared to untreated cells. The effects measured in the exposed cells indicate that the leaching of potentially genotoxic chemicals from the same surface is variable and was highest after vegetable tanning, followed by synthetic tanning and chrome tanning. These results could be due to the complex composition of the vegetable and synthetic tanning agents. Despite all limitations, these preliminary results could be useful to gain a general insight into the genotoxic potential of the processes used in the processing of natural leather and to plan future experiments with more specific cell or tissue models.     

Tethering versus Non‐Coordination of Hydroxy and Methoxy Side Chains in Arene Half Sandwich Dichloro Ruthenium Complexes

We are reporting on the hydroxyalkyl appended arene ruthenium half sandwich complexes [{η⁶‐C₆H₅(CH₂)_nOH}RuCl₂] (n = 2, 3) and the methyl ether of the hydroxypropyl derivative. Most significantly, a structural comparison between the hydroxypropyl complex 1a and its methyl ether 2a reveals, that the latter adopts the conventional dichloro bridged dimeric structure while 1a is a monomer. Coordinative saturation of the ruthenium centre is achieved by intramolecular coordination of the appended hydroxy function, thus rendering the functionalized arene an eight electron donor chelate ligand. The structure is further stabilized by intermolecular OH···Cl hydrogen bridges between a terminal chloride ligand of one and the coordinated hydroxy group of a neighbour molecule, resulting in a sheet structure. These intermolecular interactions appear to be even stronger in the hydroxyethyl analogue. Several phosphine adducts have been prepared from the hydroxy or alkoxy functionalized [(η⁶‐arene)RuCl₂]_n precursors, including water soluble P(CH₂OH)₃ adducts. Electrochemical properties of the phosphine adducts and of the dichloro bridged aryl ether complex 2a are also discussed.     

Massively parallel tabu search for the quadratic assignment problem

A new heuristic algorithm to perform tabu search on the Quadratic Assignment Problem (QAP) is developed. A massively parallel implementation of the algorithm on the Connection Machine CM-2 is provided. The implementation usesn ² processors, wheren is the size of the problem. The elements of the algorithm, calledPar_tabu, include dynamically changing tabu list sizes, aspiration criterion and long term memory. A new intensification strategy based on intermediate term memory is proposed and shown to be promising especially while solving large QAPs. The combination of all these elements gives a very efficient heuristic for the QAP: the best known or improved solutions are obtained in a significantly smaller number of iterations than in other comparative studies. Combined with the implementation on CM-2, this approach provides suboptimal solutions to QAPs of bigger dimensions in reasonable time.     

The Onset of Systemic Oxidative Stress Associated with the Accumulation of Lipid Peroxidation Product Acrolein in the Skin of Patients with Small-Vessel Vasculitis

Small-vessel vasculitis (SVV) is the inflammation of the vessel wall that can result in hemorrhage and/or ischemia. Among the histological findings in SVV are increased infiltrating neutrophils, which, due to their oxidative burst and myeloperoxidase activity, release excessive reactive oxygen species, triggering a chain reaction of lipid peroxidation and yielding reactive aldehydes such as acrolein. The implication of oxidative stress in the pathogenesis of SVV was studied, focusing on acrolein immunohistochemistry in the affected skin vessels and systemic stress response. Samples from SVV patients and healthy subjects were collected and analyzed for total serum peroxides, total antioxidant capacity, inflammatory and immunological parameters, as well as for the presence of acrolein–protein adducts in the skin tissue specimens. The obtained data showed that systemic redox homeostasis and iron metabolism are altered in SVV patients. Possible biomarkers in the evaluation of oxidative status, disease activity and prevalence were indicated. Furthermore, a strong correlation between the accumulation of acrolein–protein adducts in the skin and the progression of the disease was revealed. Thus, the results of this study demonstrate that SVV is not only associated with systemic oxidative stress but also with tissue-specific oxidative stress that promotes acrolein formation and protein modification correlating with the severity of cutaneous vasculitis.     

Bowl-shaped poly(3,4-ethylenedioxythiophene)/γ-Fe2O3 composites with elecromagnetic function

In this paper, electromagnetic poly(3,4-ethylenedioxythiophene)/γ-Fe2O3 (PEDOT/γ-Fe2O3 ) micro-bowls, 1 2 μm in diameter, were prepared by a simple environment-friendly process. In this method, the aqueous solution of cetyltrimethylammonium bromide (CTAB) instead of any organic solvent was used. FeCl3 acted as a source of Fe Ⅲ for the formation of γ-Fe2O3 and as an oxidant for the polymerization of 3,4-ethylenedioxythiophene (EDOT). The bowl-shaped morphology of PEDOT/γ-Fe2O3 composites was strongly influenced by the concentration of CTAB, FeCl2 , ammonia solution and the reaction temperature. The saturation magnetization of PEDOT/γ-Fe2O3 micro-bowls increased with the increase of FeCl2 concentration and reached 6.20 Am2 /kg at the FeCl2 concentration of 0.30 mol/L. The conductivity of the PEDOT/γ-Fe2O3 composites was in the range of 101 S/cm. The electrical and magnetic sources of PEDOT/γ-Fe2O3 micro-bowls were confirmed by SEM-EDX, TEM, XRD and XPS spectra. And the possible formation mechanism of PEDOT//γ-Fe2O3 was proposed.