JSCS Vol 70, No. 6
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Oxidative dehydrogenation of isobutane over a titanium pyrophosphate catalyst
IOAN-CEZAR MARCU, JEAN-MARC M. MILLET* and IOAN SĂNDULESCU
Department of Chemical Technology and Catalysis, Faculty of Chemistry, University of Bucharest, Blv. Regina Elisabeta No. 4–12, 030018 Bucharest, Romania
*Institut de Recherches sur la Catalyse – CNRS associé à l’Université “Claude Bernard” Lyon 1, 2, Av. Albert Einstein, 69626 Villeurbanne Cedex, France
(Received 7 June,
revised 27 September 2004)
The catalytic properties of titanium pyrophosphate in the oxidative dehydrogenation of isobutane to isobutylene were investigated in the 400 – 550 ºC temperature range. Asignificant change of the product distribution and of the apparent activation energy of the reactionwas observed at about 490 ºC. This phenomenon, already observed in the oxidative dehydrogenation of n-butane, has been interpreted by the existence of two reaction mechanisms depending upon the reaction temperature. Comparison with the n-butane reaction allowed different activation pathways for the activation of alkanes to be proposed. The catalytic properties of TiP2O7 in the oxidative dehydrogenation of isobutane was also compared to those obtained previously with several other pyrophosphates and TiP2O7 was found to be less active and selective for this reaction.
Keywords: isobutane, oxidative dehydrogenation, titanium pyrophosphate.
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The synthesis and application of
3-arylazo-4-phenylthieno[2,3-c]isothiazole and ethyl
G. G. PAWAR, P. BINEESH, P. S. R. KUMAR, D.W. RANGNEKAR and V. R. KANETKAR
Dyes Research Laboratory, Mumbai University Institute of Chemical Technology, Nathalal Parekh Marg, Matunga, Mumbai-400 019, India
(Received 22 July 2004)
The paper describes the synthesis of 3-AMino-4-phenylthieno[2,3-c]isothiazole and ethyl 3-AMino-4-phenylthieno[2,3-c]isothiazole-5-carboxylate and their utilization to prepare a range of azo disperse dyes. These novel aryl azo dyes were studied with respect to their colour and constitution relationship. The application of these dyes on a polyester fabric and their fastness properties were evaluated. These dyes were characterized by NMR, IR and visible absorption spectroscopy.
Keywords: 3-arylazo-4-phenylthieno[2,3-c]isothiazole, ethyl 3-arylazo-4-phenylthieno [2,3-c]isothiazole- 5-carboxylate, disperse dyes, polyester fabric, application.
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Synthesis of thiourea derivatives bearing the benzo[b]thiophene nucleus as potential antimicrobial agents
K. M. THAKAR, D. J. PAGHDAR, P. T. CHOVATIA and H. S. JOSHI
Department of Chemistry, Saurashtra University, Rajkot-360 005, India
(Received 30 July,
revised 22 October 2004)
The synthesis of a group of thiohydantoins and thiobarbiturates derived from 2-N-arylthiopyridocarbonyl-3,5-dichlorobenzo[b]thiophene is described. The structures of the new compounds are supported by IR, 1H-NMR and mass spectral data. These compounds were tested in vitro for their antimicrobial activities.
Keyword: thiohydantoins, thiobarbitones, antimicrobial activity.
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Expression and purification of the Sgm protein from E. coli
TATJANA ILIC TOMIC, SANDRA MARKOVIC and BRANKA VASILJEVIC
Institute of Molecular Genetics and Genetic Engineering, Vojvode Stepe 444a, P. O. Box 23, 11001 Belgrade, Serbia and Montenegro
(Received 17 June,
revised 13 September 2004)
The sgm gene from Micromonospora zionensis, the producer of the AMinoglycoside antibiotic G-52, encodes for Sgm methylasewhich modifies the target site on 16S rRNA and thus protects the producer against its own toxic product. The sgm gene wasmodified by polymerase chain reaction (PCR) and cloned in the QIAexpress pQE-30 vector in order to make a construct that places the (His)6 tag at the N-terminus of the protein. The resulting expression construct was transformed in the E. coli strain NM522 and the functional activity of the Sgm-His fusion protein was confirmed in vivo. Purification of the (His)6-tagged Sgm protein by Ni-NTA affinity chromatography was performed under native conditions and the protein was detected on a sodium dodecyl sulfate polyacrylAMide gel. Sgm methylase was purified to homogeneity > 95 %. Polyclonal antibodies raised to purified (His)6-tagged Sgm protein were used to identify this protein byWestern blot analysis.
Keywords: Sgm methylase, Micromonospora zionensis, expression, E. coli, purification.
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AFM studies of DNA structures extracted from adriAMycin treated and non-treated Ehrlich tumor cells
M. AVRAMOV IVIC*, S. D. PETROVIC**,***, E. KALMÁN******, T. MILOSAVLJEVIC***, I. RELJIN****,
B. RELJIN****, G. BOGDANOVIC*****, V. VIT. BALTIC***** and Z. KERESZTES******
*ICTM, Institute of Electrochemistry, University of Belgrade, Njegoseva 12, Belgrade
**Faculty of Technology and Metallurgy, Department of Organic Chemistry, Karnegijeva 4, P. O. Box 494, Belgrade
***Hemofarm Group, Pharmaceutical-Chemical Industry, Vrsac
****Faculty of Electrical Engineering, University of Belgrade, Bulevar Kralja Aleksandra 73, Belgrade
*****Institute of Oncology Sremska KAMenica, 21204 Sremska KAMenica, Institutski put 4, Serbia and Montenegro
******Chemical Research Center, Department of Nanostructures and Surface Modification, Budapest 1025, Pusztaszeri ut. 59-67, Hungary
(Received 6 August,
revised 12 October 2004)
Atomic force microscopy (AFM), a unique tool to investigate drug treatment of cancer cells, was used to analyze the anti-neoplastic activity of adriAMycin by comparing DNA structures of non-treated and adriAMycin-treated Ehrlich tumor cells. The non-treated cells exhibited a highly branched intact chromatin structure, related to the intensive DNA replication in cancer cells. Images from adriAMycin-treated tumor cells showed that the DNA chains were broken and the chromatin structure had been destroyed. Possible explanations for these effects of adriAMycin are considered: breakage of hydrogen bonding, oxidation and intercalation effects, as well as the poisoning of topoisomerase enzyme. DNA fractal andmultifractal analyses, performed in order to evaluate the degree of bond scission, showed that the treated DNA had become more fractal compared to non-treated DNA.
Keywords: adriAMycin, Ehrlich tumor cells, atomic force microscopy, topoisomerase, fractal and multifractal analysis.
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Spectral, thermal and magnetic characterization of 2,3-dimethoxybenzoates of Co(II), Ni(II) and Cu(II)
WIESŁAWA FERENC, AGNIESZKA WALKÓW-DZIEWULSKA, PAWEŁ SADOWSKI and JANUSZ CHRUŚCIEL*
Faculty of Chemistry, Maria Curie-Sk»odowska University, Pl 20-031, Lublin
*Institute of Chemistry, University of Podlasie, Pl 08-110 Siedlce, Poland
(Received 22 June,
revised 6 October 2004)
Complexes of 2,3-dimethoxybenzoates of Co(II), Ni(II) and Cu(II) have been synthesized as hydrated or anhydrous polycrystalline solids and characterized by elemental analysis, IR, FIR and electronic spectroscopy, magnetic studies and X-ray diffraction measurements. The carboxylate groups bind as monodentate or symmetrical, bidentate chelating and bridging ligands. The thermal stabilities were determined in air. When heated they dehydrate to form anhydrous salts which are decomposed to the oxides of the respectivemetals. Themagnetic susceptibilities of the
complexes weremeasured over the range 77–300 K and themagnetic moments were calculated. The results show that the complexes of Ni(II) and Co(II) are high-spin complexes and that of Cu(II) forms a dimer.
Keywords: 2,3-dimethoxybenzoates of Co(II), Ni(II), Cu(II), thermal stability, magnetic properties, electronic spectra of complexes.
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Investigation of the possibility of the reutilization of some industrial wastes
A. KOSTIC-PULEK, S. MARINKOVIC, S. POPOV and J. DJINOVIC
University of Belgrade, Faculty of Mining and Geology, Djusina 7, 11000 Belgrade, Serbia and Montenegro
(Received 9 June 2004)
The utilization of nitrogypsum and bottom ash, wastes from the factory “Milan Blagojevic” (Lucani–Serbia), was investigated. For this purpose, mixtures composed of calcined
nitrogypsum (CaSO4·0.5H2O), ash (mass ratio 1:1) and water (water/solid mass ratio 0.5), as well as similar mixtures consisting of 1.0 mass%5.0 mass%10.0mass%of lime (CaO) with the sAMe gypsum/ash andwater/solid mass ratios, were prepared.These mixtures gave solidified products at room temperature and atmospheric pressure, which after 28 days had satisfactory compressive strengths for application in the civil industry. The productwith 5.0 mass% of added lime has the best mechanical characeristics. X-ray and qualitative IR analysis showed that this
product mainly consisted of calcium sulphate dihydrate (CaSO4·2H2O) and carbonates, as well as a small quantity of ettringite (3CaO·Al2O3·3CaSO4·32H2O).
Keywords: fly ash, nitrogypsum, ettringite, FaL-G binder.
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Liquid–liquid extraction of gallium(III) with n-octylaniline from succinate media
T. N. SHILMKAR, S. S. KOLEKAR andM. A. ANUSE
Analytical Chemistry Laboratory, Department of Chemistry, Shivaji University, Kolhapur-416 004, India
(Received 16 June,
revised 18 October 2004)
The distribution equilibrium of gallium(III) between n-octylaniline dissolved in toluene and acidic aqueous succinate media has been investigated as a function of the concentration of extractant in the organic phase and concentration of hydrogen ions and gallium(III) ions in the aqueous phase. The stoichiometry of the extracted species was determined on the basis of slope analysis.Gallium(III) is extracted by the anion exchange mechanism as [RNH3+Ga(succinate)2]org. The temperature dependence of the extraction equilibria was exAMined by the temperature variationmethod. The extraction process is favoured with increasing temperature. It was found that a large number of cations and anions have a high tolerance limit. The selectivity of the extraction is increased by the use of suitable masking agents. The method affords the binary separation of gallium(III) from associated elements and was further extended to the analysis of a synthetic mixture.
Keywords: gallium(III), n-octylaniline, solvent extraction, succinate media, selective separation.
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Kinetics and mechanism of As2S2 oxidation
IVAN N. MIHAJLOVIC, NADA D. STRBAC, ZIVAN D. ZIVKOVIC and ILIJA ILIC*
Technical Faculty, University of Belgrade, VJ 12, 19210 Bor
*Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade, Serbia and Montenegro
(Received 7 July,
revised 19 October 2004)
The kinetics of realgar (As2S2) oxidation was studied under isothermal and non-isothermal conditions. The obtained values of the activation energy indicate that the process occurs in the kinetic domainwith the realgar particles being converted to As2O3 and As4O6 (g). The very fast reaction rates were limited by the chemical reaction. The kinetic equation was found to be:
–ln (1–a) = 4.56 × 103 × e(–8780/T) × t. The proposed reaction mechanism and chemical transformation investigated by ICP–AES, EDXRF and thermal analysis are discussed.
Keywords: thermal analysis, activation energy, As2S2, EDXRF, ICP–AES.
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Electrodeposition and characterization of Fe–Mo alloys as cathodes for hydrogen evolution in the process of chlorate
N. ELEZOVIC, B. N. GRGUR*, N. V. KRSTAJIC* and V. D. JOVIC
Center for Multidisciplinary Studies, University of Belgrade, P. O. Box 33, 11030 Belgrade, Serbia and Montenegro
*Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade
(Received 20 July,
revised 20 October 2004)
Fe–Mo alloys were electrodeposited from a pyrophosphate bath using a single diode rectified AC current. Their composition and morphology were investigated by SEM, optical microscopy and EDS, in order to determine the influence of the deposition conditions on the morphology and composition of these alloys. It was shown that the electrodeposition parAMeters, such as: chemical bath composition and current density, influenced both the composition of the Fe–Mo alloys and the current efficiency for their deposition, while the micro and macro-morphology did not change significantly with changing conditions of alloy electrodeposition. It was found that the electrodeposited Fe–Mo alloys possessed a 0.15 V to 0.30 V lower overvoltage than mild steel for hydrogen evolution in an electrolyte commonly used in commercial chlorate production, depending on the alloy composition, i.e., the conditions of alloy electrodeposition.
Keywords: Fe–Mo alloy, electrodeposition, morphology, catalitic activity.
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Electrochemical behaviour of titanium alloys in artificial saliva
DANIEL MARECI, CATALIN BOCANU, GHEORHE NEMTOI* and DELIA AELENEI**
Technical University Gh. Asachi Iasi, Faculty of Industrial Chemistry, Physical Chemistry Department, Bd. D.Mangeron, No. 71, 700050, Iasi, Romania
*University Alexandru Ioan Cuza Iasi, Faculty of Chemistry, Department of Theoretical and Physical Chemistry, Bd. Carol, No. 11, 700056, Iasi, Romania
**Technical University Gh. Asachi Iasi, Faculty of Materials Science, Bd. D.Mangeron, No. 75, 700050, Iasi, Romania
(Received 18 June,
revised 11 Oktober 2004)
Titanium alloys are used i n odontology applications owing to their excellent biocompatibility. The corrosion resistance of titanium alloys is an important component of their biocompatibility. In this study, the electrochemical corrosion resistance of Ti6Al4V, Ti6Al7Nb, Ti6Al2Nb1Ta1Mo, Ti5Al2,5Fe and commercial titanium in Afnor saliva was investigated. Maintaining titanium and Ti6Al7Nb alloy in Afnor saliva for 7 days results in the formation of a protective layer, the resistance of which is high and could be comparedwith that of a passive layer resulting from electrochemical treatment. The replacement of vanadium with niobium or iron favours the passivation, thus increasing the corrosion resistance.
Keywords: titanium alloys, cyclic voltAMmetry, corrosion, passivation.
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Liquid chromatographic determination of fumonisins B1 and B2 in corn sAMples after reusable immunoaffinity column clean-up
BILJANA F. ABRAMOVIC, SANDRA M. JAKSIC* and ZORAN S. MASIC*
Faculty of Science, Department of Chemistry, Trg D. Obradovica 3, 21000 Novi Sad
*Scientific Veterinary Institute “Novi Sad”, Rumenacki put 20, 21000 Novi Sad, Serbia and Montenegro
(Received 26 June,
revised 18 October 2004)
The possibility of the liquid chromatographic determination of fumonisins B1 (FB1) andB2 (FB2) in corn sAMples with a reused immunoaffinity column (IMA) for the clean-up of the sAMples was investigated. After optimization of the chromatographic determination of FB1 and FB2 derivatized with o-phthaldialdehyde- 2-mercaptoethanol, the efficiency of the clean-up of spiked corn extracts with reuse of the IMA columns was studied, both with and without column regeneration. It was found that the IMAcolumn, designated for single-use only, can be used at least five times without regeneration and additional five times after regeneration. Regeneration consists of leaving the phosphate buffer saline solution on the column for one day at 4 ºC. The efficiency of the columns was tested by determining the recovery of FB1 and FB2, as well as the reproducibility of the determinations. The mean recoveries of FB1 and FB2 from corn spiked with FB1 at 1.0 mg/g and with FB2 at 0.5 mg/g (on the basis of 10 measurements) were 88.7%(RSD 10.2%) and 90.5%(RSD 6.1 %), respectively.
Keywords: mycotoxins, fumonisins, liquid chromatography, immunoaffinity column, regeneration, corn analysis.
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Physico-chemical investigation of synthesis of lead salts from sulfide lead concentrate
ALEXANDER G. KHOLMOGOROV, OLGA N. KONONOVA*, LARISSA V. SHASINA,
OKSANA A. STREKATOVA , TATIANA V. KADETOVA and ALEXANDER A. SABETSKIY*
Institute of Chemistry and Chemical Technology, Siberian Department of the Russian Academy of Science, Karl Marx Pr. 42, 660049 Krasnoyarsk, Russia
*Department of Chemistry, Krasnoyarsk State University, Svobodny Pr., 79, 660041 Krasnoyarsk, Russia
(Received 9 July 2004)
The leaching of lead from lead–zinc concentrates by iron(III) salt solutins in the absence, as well as in the presence of mineral acids (HCl, H2SO4, HNO3) has been investigated. It was shown that the leaching of lead by means of 0.3 M Fe(NO3)3 at (22 ± 1) ºC leads to practically complete recovery of lead during 1 h. This conclusion was confirmed by data obtained using chemical, thermographical and X-ray photographical methods. Atechnological scheme for the synthesis of lead salts and oxides without the production of metal lead has been developed as a result of the present investigation.
Keywords: lead–zinc concentrates, leaching, synthesis, lead compounds.
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The Division of Analytical Chemistry of the
European Association for Chemical and Molecular Sciences (EuCheMS)
European Analytical Column No. 33
Copyright &AMp; copy; SHD 2005.
August 24, 2005.
For more information contact: JSCS@tmf.bg.ac.yu