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Open access

Osama I. El-Sabbagh, Yamany B. Yamany and Hany A. Eldeab

Abstract

Novel complexes of Ru (III), Cu (II) and Au (III) (2–4) were prepared using 6-phenyl-2-thioxo-4-(trifluoromethyl)-1,2- dihydropyridine-3-carbonitrile (HL, 1) adopting either electrochemical or traditional chemical methods. The electrochemical method is preferred in the synthesis of the complexes than the chemical one because it affords pure products with higher yields in shorter reaction time. The novel thiopyridine complexes were characterized by elemental analyses, IR, 1H, 19F-NMR, TGA and DTA measurements. The antimicrobial activity evaluation revealed that the complex bearing copper metal 3 has nearly the same activity as the reference drug ciprofloxacin. Anti-inflammatory activity evaluation showed that complex 4 containing gold displayed anti-inflammatory activity higher than the reference drug celecoxib upon using carrageenan rat hind paw edema method.

Open access

Stefan Demcak, Magdalena Balintova, Maria Demcakova, Inga Zinicovscaia, Nikita Yushin and Marina V. Frontasyeva

Abstract

The heavy metal removal from wastewater is very important due to their persistent character in aquatic environment. The use of wooden sawdust is emerging as a potential alternative to the existing conventional technologies for the removal of metal ions from aqueous solutions. The aim of this work is to study the Cu(II) removal of from water by unconventional waste products including the wooden sawdust of poplar, cherry, spruce and hornbeam. The FT-IR spectra of the studied wooden sawdust confirmed the presence of functional groups that have potential for heavy metal binding. The highest efficiency of Cu(II) removal was observed for poplar wooden sawdust at static (86 %) and dynamic (88 %) adsorption experiments. Data obtained by neutron activation analysis revealed that ion exchange is also a mechanism of metal removal by the selected wooden sawdust.

Open access

Krzysztof Kowalczyk, Justyna Gołąbek, Katarzyna Przywecka and Barbara Grzmil

Abstract

Anticorrosive epoxy and polyurethane coatings were compounded using zinc-free nanosized phosphates of strontium (SP) or strontium and aluminum (SAP). For comparison, a nanosized calcium aluminum ammonium phosphate (CAP) and a microsized zinc phosphate (ZP) were tested. Results of salts spray and cyclic corrosion tests revealed better anticorrosive properties of the SAP-based coatings in relation to the samples with the other Zn-free fillers or ZP. Electrochemical noise tests of uncoated steel in aqueous suspensions of the phosphates exhibited similar corrosion inhibition efficiency of the Sr-based phosphates and ZP, and worse anticorrosive features of CAP. Electrochemical impedance spectroscopy did not show better protective properties of ZP-based coatings than the samples with the Zn-free fillers.

Open access

Mira Cheribet Drouiche, Karim Moussaceb, Emmanuel Joussein and Jean-Claude Bollinger

Abstract

The objective of this work is to use stabilization/solidification (S/S) on the landfill leachates that often are heavily polluted by heavy metals and require proper treatment before discharge into the environment. The process consists of a S/S using a hydraulic binder in order to limit the solubility and mobility of the pollutants. While cement is the most used binder based on S/S values, in this study we substituted it by cement kiln dust (CKD) in two replacement ratios 25.50 and 100 %. The resulting effect on mechanical resistance and on retention of pollutants was evaluated. A metal (lead, iron and zinc) contaminated leachate from the landfill site of Sidi-Bouderham in Algeria was mixed with an amount of cement and cement kiln dust in different proportions in order to optimize our formulations. The smooth paste was obtained and a standardized test of the test specimens was analyzed for mechanical resistance after 7 and 28 d of setting. Our results show that F1P (100 % Cement) and F2P (75 % Cement + 25 % CKD) point on satisfactory mechanical strength and metal retention capacity. Our approach suggests a promising approach for remediation of polluted sites.

Open access

K. Szmuc, M. Kus-Liskiewicz, Ł. Szyller, D. Szmuc, M. Stompor, I. Zawlik, T. Ruman, S. Wołowiec and J. Cebulski

Abstract

The composite containing nanosilver uniformly deposited on matrix composed of CaHPO4 x 2H2O (brushite, ca 89 mass %), CaHPO4 (monteonite, ca 9.5 mass%), and Ag3PO4 (0.5 mas%) was obtained by addition of calcium nitrate and silver nitrate aqueous solution at 30:1 Ca:Ag molar ratio into excess of (NH4)2PO4 solution at pH 5.0 – 5.5. The isolated solid was characterized by STEM, XRD, and LDI mass spectrometry. It has been found that nanosilver was uniformly distributed within composite as <10 nm diameter sized nanoparticles. Determination of silver by AAS showed that 60% of silver is present as Ag(0) nanoparticles, the present as matrix Ag3PO4 as identified by XRD method. The composite showed strong growth inhibition in E. coli and P. aeruginosa strains, and moderate towards S. aureus. The C. albicans cells were the most resistant to the tested material, although still composite was moderately cytostatic for the yeast.

Open access

Mohammed A. Abdulaziz, Abdulrahman A. Bakri, Saleh A. Al-Zahrani, Majed S. Al-Zahrani, Abdulrahman N. Al-Lehebi, Fadil M. Banjar and Mohand I. Nabag

Abstract

This study aims at investigating the potential of Acacia gerrardii pod for the removal of Cr(VI) in batch system. Effect of solution pH, biosorbent dosage, initial concentration of Cr(VI), contact time on the removal process was examined. Complete removal of hexavalent chromium was achieved at pH values 1.0 and 2.0 whereas maximum removal of total chromium was obtained at pH of 3.0. The study showed that the biosorption and bioreduction mechanisms were involved in the removal process. The time required for complete removal of Cr(VI) using the pod of Acacia gerrardii was shortened with an increase in biomaterial dosage and decrease in Cr(VI) concentration. Kinetic data was well described using Park kinetic model. Freundlich isotherm model adequately fitted the equilibrium data indication multilayer adsorption of total chromium on the surface of biomaterial. The pod of Acacia gerrardii could be used efficiently for the removal of hexavalent chromium from aqueous solutions.

Open access

Yevheniia Konotop, Kseniia Stepanchenko, Leila-Anastasiia Karpets, Andrii Zinchenko, Mariia Kovalenko, Oleksandr Smirnov, Ludmila Batsmanova and Nataliya Taran

Abstract

Advances in nanotechnology in various fields of human activity contribute to increase of their production, improved properties and wider implementation of nanomaterials. However, increasing use may enhance their release into the environment and can lead to affecting human health. The toxicity of colloidal solutions of metal nanoparticles (Cu, Mn) and their oxides, obtained in the absence and presence of a stabilizer, was examined and compared with the use of the standard test system of Allium cepa L.. The phytotoxicity of the experimental solutions was evaluated according to the growth response of the onion roots; the cyto- and genotoxicity were estimated due to the proliferative activity of the root meristem cells. It was established that solutions of stabilized metal nanoparticles were at given concentration toxic to Allium cepa L. according to the integral index of roots growth, however, were not cytotoxic. Difference in the phytotoxicity of stabilized and non-stabilized metal nanoparticles and their oxides depended on their phase composition and affected root growth.

Open access

Marcin Nabrdalik and Michał Sobociński

Abstract

The paper presents analysis of stress distribution in the friction node of knee joint endoprosthesis where sleds are made of various titanium alloys and CoCrMo cooperate with spherical polyethylene inserts. Currently used titanium alloys consists of Nb, Ta, Zr or Mo and with lesser value of Young’s modulus than Ti6Al4V alloy, or steel CoCrMo, which significantly varies from other metal materials. The obtained results make it possible to indicate the “weak points” of the accepted solution, and thus counteract the subsequent effects resulting from premature wear of endoprosthesis elements. The analysis was conducted with numerical method of ADINA System 8.6. The Finite Elements Method allowed to compute and present stress distribution quickly in all elements of the model.

Open access

Ľubor Dlháň, Roman Krylov, Martin Kopáni and Roman Boča

Abstract

Bovine spleen has been used as a sample for deep magnetochemical investigation. Temperature dependence of the magnetic susceptibility and field dependence of the magnetization reveal a paramagnetic behaviour that violates the Curie law. The zero-field cooled magnetization and field cooled magnetization experiments show the bifurcation point at ca T C = 20 K and the blocking temperature T B = 10 K confirming a dominating portion of ferritin along with the organic tissue. There is a remnant magnetization at temperature below 20 K and the search for the magnetic hysteresis was positive.

Open access

Ilona Trawczyńska

Abstract

Permeabilization is one of the effective tools, used to increase the accessibility of intracellular enzymes. Immobilization is one of the best approaches to reuse the enzyme. Present investigation use both techniques to obtain a biocatalyst with high catalase activity. At the beginning the isopropyl alcohol was used to permeabilize cells of baker’s yeast in order to maximize the catalase activity within the treated cells. Afterwards the permeabilized cells were immobilized in calcium alginate beads and this biocatalyst was used for the degradation of hydrogen peroxide to oxygen and water. The optimal sodium alginate concentration and cell mass concentration for immobilization process were determined. The temperature and pH for maximum decomposition of hydrogen peroxide were assigned and are 20°C and 7 respectively. Prepared biocatalyst allowed 3.35-times faster decomposition as compared to alginate beads with non permeabilized cells. The immobilized biocatalyst lost ca. 30% activity after ten cycles of repeated use in batch operations. Each cycles duration was 10 minutes. Permeabilization and subsequent immobilization of the yeast cells allowed them to be transformed into biocatalysts with an enhanced catalase activity, which can be successfully used to decompose hydrogen peroxide.