bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of 5-hydroxymethylfurfural after Winkler and by the HPLC method for authentication of honey
Authors: Kukurova K. , Karovičová J. , Greif G. , Kohajdová Z. , Lehkoživová J. 
Published: August 2006

AbstractThe quality and authenticity of commercially available honey from Slovak market and the development of HPLC method for determination of hydroxymethylfurfural (HMF) content of honey with fine separation efficiency, sensitivity, applicability, and recovery was evaluated.Physicochemical parameters (moisture, total acidity, content of proline, saccharides, and value of electrical conductivity) have been determined.
Spectral and electrochemical study of coordination molecules Cu4OX6L4: 3-Pyridylmethanol and 4-pyridylmethanol Cu4OBrnCl(6−n)(pm)4 complexes
Authors: Ondrejovič G. , Kotočová A. 
Published: August 2006

AbstractThe tetranuclear Cu4OBrnCl(6−n)(pm)4 complexes, where pm = 3-pyridylmethanol (3-pm), 4-pyridylmethanol (4-pm) and n = 0−6 with trigonal bipyramidal coordination of copper(II) were prepared and their infrared and electronic absorption spectra as well as cyclic voltammograms in nitromethane solutions were measured. The molecules exhibit strong single infrared Cu4O stretching absorptions between 580 and 530 cm−1 which are in linear correlations with the number of halides, n. Far infrared absorptions assigned to Cu-Br, Cu-Cl, and Cu-N stretching vibrations appear at higher wavenumbers for 3-pm complexes compared with those for 4-pm complex molecules. Two strongly overlapped d–d bands in the region 11300–13100 cm−1 assigned to $$e(d_{x^2 - y^2 } ,d_{xy} ) \to a_1 (d_{z^2 } )$$ and e(d xz, d yz) → a 1(d z 2) transitions in the trigonal bipyramidal coordination of the copper(II) atoms were resolved by Gaussian analysis. Both, 3-pm and 4-pm ligands produce in the complex molecules almost the same ligand field. The maxima of the Gaussian d–d components vary with the parameter n and are for both series of the complexes deviated from linearity, more for the low-energy d–d bands than for high-energy analogues. The electrochemical reduction in nitromethane is significantly less reversible for 4-pm complex molecules compared with that of 3-pm analogues. Formal reduction potentials E′ c for 3-pm complexes were observed in the range 478 (n = 0)−599 (n = 6) mV. The plot E′ c vs. n is significantly deviated from linearity. It is suggested that the reducing electrons enter the half-filled d z 2 orbital of the copper(II) atom. The different spectral and electrochemical results obtained for 3-and 4-pm complexes are explained by different structural distortions, bond lengths, and charge distributions produced by halide ligand variations. The results are also discussed with previously reported data on analogous pyridine, 3-methylpyridine and 4-methylpyridine complexes.
Magnetic, spectral, and thermal behaviour of 2-chloro-4-nitrobenzoates of Co(II), Ni(II), and Cu(II)
Authors: Ferenc W. , Cristóvão B. , Mazurek B. , Sarzyński J. 
Published: August 2006

AbstractSome physicochemical properties of 2-chloro-4-nitrobenzoates of Co(II), Ni(II), and Cu(II) were studied. The complexes were obtained as mono-and dihydrates with a metal ion—ligand mole ratio of 1: 2. All complexes are polycrystalline compounds. Their colours depend on the kind of central ion: pink for Co(II) complex, green for Ni(II), and blue for Cu(II) complexes. Their thermal decomposition was studied only in the range of 293 K–523 K because it was found that on heating in air above 523 K 2-chloro-4-nitrobenzoates decompose explosively. Hydrated complexes lose crystallization water molecules in one step. During dehydration process no transformation of the nitro group to nitrito one took place. Their solubilities in water at 293 K are of the orders of 10−3-10−2 mol dm−3. The magnetic moment values of 2-chloro-4-nitrobenzoates determined in the range of 76 K–303 K change from 3.48µB to 3.82µB for Co(II) complex, from 2.24µB to 2.83µB for Ni(II) 2-chloro-4-nitrobenzoate, and from 0.31µB to 1.41µB for Cu(II) complex. 2-Chloro-4-nitrobenzoates of Co(II) and Ni(II) follow the Curie—Weiss law, but the complex of Cu(II) forms dimer.
Synthesis, characterization, and biological activities of some transition metal(II) complexes with the thiosemicarbazone derived from 4-[1-(4-methylphenylsulfonyl)-1H-indol-3-yl]but-3-en-2-one
Authors: Qu J. , Sun G. , Wang L. , Qu L. 
Published: August 2006

AbstractA new 4-[1-(4-methylphenylsulfonyl)-1H-indol-3-yl]but-3-en-2-one thiosemicarbazone (HL) was synthesized derived from 4-[1-(4-methylphenylsulfonyl)-1H-indol-3-yl]but-3-en-2-one. Four transition metal(II) complexes of HL have been prepared. Elemental analysis, molar conductivity, IR, UV, 1H NMR spectra, and TG-DTA have been used to characterize these complexes. The complexes have the general formula ML2, where M = Zn, Cu, Co, and Ni. The ligand and its complexes have been studied for their possible biological activity including anti-inflammatory, antibacterial, and antitumour activity in vitro.
Crystal structure and thermal chemical properties of 2-(2,4-dimethylanilino)-3-methyl-6-diethylaminofluorane
Authors: Li X. , Ding C. , Tian B. , Liu Q. , Zhang S. , Xu H. , Ouyang P. 
Published: August 2006

AbstractThe crystal structure of 2-(2,4-dimethylanilino)-3-methyl-6-diethylaminofluorane has been determined by single crystal X-ray diffraction method. The crystal belongs to triclinic system, space group P-1 with unit cell constants a = 11.2877(9) Å, b = 11.9539(9) Å, c = 12.2365(9) Å, α = 97.2580(10)°, β = 116.2850(10)°, γ = 106.3710(10)°, V = 1358.48(18) Å 3, Z = 2, D c = 1.234 g/cm3, μ = 0.079 mm−1, F(000) = 536, R and w(R) are 0.0718 and 0.2055, respectively, for 5239 unique reflections with 3745 observed reflections (I > 2σ(I)).
Synthesis and reactions of 2-and 4-substituted furo[3,2-c]pyridines
Authors: Búdová M. , Fojtíková K. , Miklovič J. , Mrázová V. , Horváth B. , Krutošíková A. 
Published: August 2006

AbstractSubstituted furopropenoic acids were prepared from appropriate aldehyde under the Doebner’s conditions. Obtained acids were converted to the corresponding azides, which were cyclized by heating in Dowtherm to furopyridones. These compounds were aromatized with phosphorus oxychloride to chloro derivatives of furo[3,2-c]pyridine (Va, Vb). Chloro derivative Vb was reduced with hydrazine hydrate to 2-(4-aminophenyl)furo[3,2-c]pyridine in ethanol and Pd/C as a catalyst. Chloro derivative Va was converted to 4-amino-2-(3-pyridyl)furo[3,2-c]pyridine under the same conditions. The chlorine atom in other chloro derivatives (VIIa, VIIb) was replaced by nucleophilic substitution with alkoxides (sodium ethoxide, propoxide, and isopropoxide) and the corresponding alkoxy derivatives were formed. By reaction of VII with cyclic secondary amines (morpholine, piperidine, and pyrrolidine) 4-substituted furopyridines were prepared.
Synthetic approaches towards bisspiro[naphthalene-2(1H),3′-(3H)pyrazol]-1-one-containing compounds
Authors: Girgis A. , Osman F. , El-Samahy F. , Ahmed-Farag I. 
Published: August 2006

Abstract1,3-Dipolar cycloaddition reaction of bis{[4-(3,4-dihydro-(2H)-naphthalen-1-oxo-2-yl)methyl-idenephenyl]oxy}alkanes with nitrilimines (generated in situ by triethylamine dehydrohalogenation of the corresponding hydrazonoyl chlorides) in refluxing dry benzene afforded a mixture of monocycloadduct and dicycloadduct products in high regioselectivity. On the other hand, reaction of bis{[2-(3,4-dihydro-(2H)-naphthalen-1-oxo-2-yl)methylidenephenyl]oxy}alkanes with nitrilimines gave the corresponding dicycloadducts as the only isolable regioisomers.
Mild Pfitzner—Moffat oxidation of the (1→3)-β-D-glucan from Saccharomyces cerevisiae
Authors: Zeković D. , Radulović M. , Nastasović A. , Vrvić M. , Jakovljević D. , Kogan G. 
Published: August 2006

AbstractThe structure of the cell wall glucan isolated from the industrial strain of Saccharomyces cerevisiae was characterized as to be composed of a linear (1→3)-β-D-glucan chain with single β-D-glucopyranosyl residues attached to every ninth backbone unit by (1→6)-glycosidic linkages. Mild oxidation of this β-D-glucan with a dimethyl sulfoxide—acetic anhydride reagent yielded an “oxidized” glucan with aldehyde groups introduced at C-6 and carbonyl oxygens located at C-2 and C-4 of the glucopyranosyl rings. The conversion of the oxidized glucan into the polyoxime was used to study the progress of oxidation and to establish the carbonyl groups distribution in this new reactive polysaccharide derived from baker’s yeast cell wall.
Limited sample recovery in coupled methods of high-performance liquid chromatography of synthetic polymers
Authors: Berek D. , Russ A. 
Published: August 2006

AbstractComplex polymer systems, which exhibit multiple distributions in their molecular parameters can be characterized by coupled liquid chromatographic methods. The latter combine entropic (exclusion) and enthalpic (interaction) retention mechanisms. However, recent experimental results suggest that some coupled liquid chromatographic methods may suffer from incomplete sample recovery. This refers, for example, to liquid chromatography under critical conditions of enthalpic interactions and to eluent gradient liquid chromatography. Sample recovery in both latter methods was investigated for selected model systems applying adsorption retention mechanism. Reduced sample recovery was confirmed for both methods. It was revealed that even very high final strength of mobile phase may be insufficient for complete elution of polymer samples in eluent gradient polymer liquid chromatography.
Influence of medium on the kinetics of oxidation of iron(II) ion with t-butyl hydroperoxide
Authors: Mihaljević B. , Ražem D. 
Published: August 2006

AbstractThe oxidation of iron(II) with tert-butyl hydroperoxide was investigated in the absence of oxygen in water, methanol, and the dichloromethane—methanol solvent mixture (φr = 2:1). The oxidation rate depends on solvent polarity; measured in the presence of SCN− at constant 0.8 mmol dm−3 HCl, the rate constant increases with the polarity decrease passing from water and methanol to the dichloromethane—methanol solvent mixture. Further, in non-aqueous solutions at this acid concentration the rate constant was higher than the rate constant in the presence of Cl− only. The oxidation rate measured in the [FeCl]2+ complex in dichloromethane—methanol was slow in acidic medium and increased by decreasing the acid concentration. Approaching the physiological pH conditions the rate constant attained the value of an order of magnitude of 103 dm3 mol−1 s−1, while very little alteration of stoichiometry of the oxidation reaction was observed. The rate constant measured in the presence of Cl− strongly depends on electrolyte concentration at concentrations less than 0.5 mmol dm−3 HCl, both in MeOH and the solvent mixture. Based on these results, a possible mechanism of the influence of solvent, acidity, and ligand type on the rate constant is discussed. We assume that the oxidation proceeds by an inner-sphere mechanism considering that the breakdown of the successor inner-sphere complex forming reactive alkoxyl radicals is probably the rate-limiting step.
Synthesis of new thiazolo[2,3-b]pyrimidine derivatives of pharmaceutical interest
Authors: Abdel-Razik H. 
Published: August 2006

Abstract2H-5-Amino-6-cyano-3,7-dioxothiazolo[2,3-b]pyrimidine was subjected to ring formation affording thiazolo[2,3-b]pyrimidine derivatives. 2H-5-Amino-6-cyano-3,7-dioxo-2-phenylmethylenethiazolo[2,3-b]pyrimidine was also subjected to ring formation affording pyrimido[4,5-d]-, pyrano[2,3-d]-, and pyrido[2,3-d]thiazolo[2,3-b]pyrimidine derivatives. 2-Anilinothiocarbonyl-3,9-dioxo-8-imino-7-phenyl-6-thioxothiazolo[2,3-b]pyrimido[4,5-d]pyrimidine and 8-amino-3,9-dioxo-6-thioxothiazolo[2,3-b]pyrimido[4,5-d]pyrimidine reacted with α-haloactive-methylene compounds to afford heterocyclic compounds containing two, fused and isolated, thiazole moieties, respectively.
Enthalpic analysis of the CaTiSiO5 system
Authors: Nerád I. , Kosa L. , Mikšíková E. , Adamkovičová K. 
Published: August 2006

AbstractThe relative enthalpy of titanite and enthalpy of CaTiSiO5 melt have been measured using drop calorimetry between 823 K and 1843 K. Enthalpies of solution of titanite and CaTiSiO5 glass have been measured by the use of hydrofluoric acid solution calorimetry at 298 K. Enthalpy of vitrification at 298 K, δvitr H(298 K) = (80.7 ± 3.4) kJ mol−1, and enthalpy of fusion at the temperature of fusion 1656 K, δfus H(1656 K) = (139 ± 3) kJ mol−1, of titanite have been determined from experimental data. The obtained enthalpy of fusion is considerably higher than up to the present published values of this quantity.
Kinetic, spectrophotometric determination of nanogram levels of manganese(II) using catalytic azo dye—potassium periodate—1,10-phenanthroline system
Authors: Mutaftchiev K. 
Published: August 2006

AbstractThe catalytic effect of manganese(II) on the oxidation of the dye, sodium salt of 4-(2-hydroxynaphth-1-ylazo)benzenesulfonic acid, with potassium periodate in the presence of 1,10-phenanthroline in weakly acidic media was studied. The reaction was followed spectrophotometrically by measuring the decrease in the absorbance of the dye at λ = 483 nm. Under the optimum conditions Mn(II) concentration within the range of 0.08–4 ng cm−3 could be determined by the fixed-time method with a detection limit of 0.025 ng cm−3. The method was applied for the determination of manganese content in tomatoes, aubergine, white radish, and French beans. The results showed a good agreement with those obtained by atomic absorption spectrophotometry.
Application of a ternary complex of tungsten(VI) with 4-nitrocatechol and thiazolyl blue for extraction-spectrophotometric determination of tungsten
Authors: Lekova V. , Gavazov K. , Dimitrov A. 
Published: August 2006

AbstractA new ternary ion-association complex of tungsten(VI), 4-nitrocatechol (NC), and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (Thiazolyl Blue, MTT) was obtained and studied using an extraction-spectrophotometric method. The optimum pH, reagent concentrations, and extraction time were determined. The composition of the complex was found to be W(VI): NC: MTT = 1: 2: 2. The extraction process was investigated quantitatively and the key constants were calculated. The molar absorptivity of the chloroform extract at λmax = 415 nm was 2.8 × 104 dm3 mol−1 cm−1, and the Beer’s law was obeyed up to 8.8 μg cm−3 tungsten(IV). The limit of detection and limit of quantification were calculated to be 0.27 μg cm−3 and 0.92 μg cm−3, respectively. The effect of foreign ions and reagents was studied and a competitive method for determination of tungsten in products from ferrous metallurgy was developed. The residual standard deviation and the relative error were 0.53 % and 0.2 %, respectively.
Determination of risperidone at picogram level in human urine by luminol—H2O2 chemiluminescence
Authors: Xie X. , Shao X. , Song Z. 
Published: August 2006

AbstractA simple flow-injection chemiluminescence method with synergistic enhancement has been investigated for the rapid and sensitive determination of antipsychotic risperidone. The synergistic action was significant in the chemiluminescence system of luminol—hydrogen peroxide with risperidone as an enhancer. The increased chemiluminescence intensity was correlated with risperidone concentration within the range from 10 pg mL−1 to 1.0 ng mL−1 with relative standard deviations lower than 5.0 % and the detection limit of 4 pg mL−1. At a flow rate of 2.0 mL min−1, the flow-injection chemiluminescence method exhibited both a high sensitivity and excellent selectivity giving a throughput of 120 times per hour. The proposed method was successfully applied to determine the risperidone content in human urine without any pretreatment. It was found that the excretive amounts of risperidone reached their maximum after taking 2.0 mg of risperidone for 1 h, with a total excretive ratio of 17.37 % in 8.5 h.
Electrochemical dissolution of chalcopyrite studied by voltammetry of immobilized microparticles
Authors: Pikna L’. , Lux L. , Grygar T. 
Published: August 2006

AbstractThe characteristics of anodic electrochemical dissolution of chalcopyrite (CuFeS2) powder in hydrochloric acid medium with sodium chloride have been studied. Cyclic voltammetry and chronopotentiometry of immobilized microparticles using paraffin-impregnated graphite electrode was employed. Present work is focused on electrochemical identification of chalcopyrite cathodic and anodic reaction products within the potential range of −0.7 to +0.8 V (vs. SCE) in hydrochloric acid solution containing sodium chloride and/or copper(II) chloride.
Colon tissue concentrations of copper, iron, selenium, and zinc in colorectal carcinoma patients
Authors: Hornik P. , Milde D. , Trenz Z. , Vysloužil K. , Stužka V. 
Published: August 2006

AbstractConcentration of four trace elements (copper, zinc, iron, and selenium) was determined in colon tissue from twenty-three patients with colorectal cancer. The tissue samples were dried and dissolved using microwave-assisted digestion technique. The content of trace elements was determined using atomic absorption spectrometry. No significant differences between Zn levels in normal and cancerous tissues were observed. However, the levels of Cu, Fe, and Se were significantly higher in cancerous tissues than in the control samples.The results obtained sing microwave-assisted technique were compared to those obtained via alkaline digestion with tetramethylammonium hydroxide. Both techniques were used for the digestion of certified reference material of pork liver. Very good agreement with the certified values of Cu, Fe, and Zn in the reference material was achieved using alkaline digestion procedure. This technique seems to be an efficient alternative to decomposition of biological samples.
Structure of tetrakis(pyridinioacetate) neodymium(III) tetrahydrate perchlorate
Authors: Song Y. , Yao X. , Deng T. , Wu J. , Wu Q. 
Published: August 2006

AbstractThe structure of tetrakis(pyridinioacetate) neodymium(III) tetrahydrate perchlorate, [Nd(pyBET)4 · 4H2O](ClO4)3, is reported. The neodymium atom is eight-coordinate dodecahedrally distorted polyhedron. The molecule consists of discrete [Nd(pyBET)4 · 4H2O]3+ cation and perchlorate anions held by ionic electrostatic force.
Thermally stable oligomer—Metal complexes based on oligo-ortho-aminophenol and oligophenylazomethinephenol
Authors: Mart H. , Koç M. , Muradoğlu V. , Yürük H. 
Published: August 2006

AbstractThe oligo-ortho-aminophenol was synthesized by the oxidative polycondensation of ortho-aminophenol with air oxygen. The oligophenylazomethinephenol was synthesized by the condensation of aniline with oligosalicylaldehyde. Metal complexes of these oligomers with Cu(II), Co(II), Zn(II), and Ni(II) were synthesized and characterized. Based on the results of thermogravimetric analysis, synthesized oligomer—metal complexes were more stable against heat and thermooxidative decomposition than some polymeric Schiff bases and polymer—metal complexes. Additionally, the presence of metal ions increased the thermal stability of oligo-ortho-aminophenol, while the thermal stability of oligophenylazomethinephenol was lowered.
Adsorption of SO2 on alumina
Authors: Fellner P. , Jurišová J. , Khandl V. , Sýkorová A. , Thonstad J. 
Published: August 2006

AbstractThe adsorption of SO2 on alumina used in the aluminium industry, the so-called smelter-grade alumina, was studied in the temperature range 15–120°C. It was found that at temperatures lower than 40°C, sulphur dioxide was bonded to alumina reversibly by physical forces, and the adsorption could be described satisfactorily by the Langmuir adsorption isotherm. The heat of adsorption was estimated to be −33 kJ mol−1. At temperatures ranging from 80°C to 120°C, which prevail in dry scrubbers in the aluminium industry, the heat of adsorption was determined to be −56 kJ mol−1. When SO2 was adsorbed at temperatures higher than 80°C, about 30 % of the SO2 could not be desorbed even if the samples were heated up to 250°C. In the presence of SO2 and oxygen, the formation of sulphate was observed at temperatures above 90°C.
One-pot, three-component synthesis of secondary amines and trisubstituted hydrazines from ketones
Authors: Tavakol H. , Zakery S. 
Published: August 2006

AbstractVarious imines and hydrazones were reduced to the corresponding amines and hydrazines using borane-tetrahydrofuran complex as a reducing agent in the solution of lithium perchlorate in diethyl ether. The initial imines or hydrazones have been prepared at the same conditions just before the reduction step. Both steps were carried out in one vessel with a good yield and insignificant formation of by-products.
Electrical conductivity of the molten KF—K2TaF7 system
Authors: Korenko M. , Kuznetsov S. 
Published: August 2006

AbstractThe specific conductivity of the molten KF—K2TaF7 system was measured within the temperature range from 1155 K to 1255 K using a two-molybdenum electrode cell. It was found that the addition of up to 10 mass % K2TaF7 caused a decrease of the system specific conductivity.
New substituted mono-and bis(imidazolyl)pyridines and their application in nitroaldolisation reaction
Authors: Keder R. , Drabina P. , Hanusek J. , Sedlák M. 
Published: August 2006

AbstractNew chiral nitrogen ligands based on the substituted mono-and bis(imidazolyl)pyridines have been prepared and characterised. Their complexes with cupric acetate were used as catalysts in the nitroaldolisation reaction. In the case of optically pure complexes of mono(imidazolyl)pyridine, the isolated products were 2-nitro-1-(2-nitrophenyl)ethanols or 2-nitro-1-(4-nitrophenyl)ethanols in overall yields of 49–93 % and with the maximum enantiomeric excess of 15.6 %. The complexes of bis(imidazolyl)pyridine also catalyse the nitroaldol reaction, the yields being 64–90 %, but with zero enantioselective excess.
20 years of scripted space
Authors: McCullough Malcolm 
Published: August 2006

AbstractMalcolm McCullough is an advocate of the importance of play and manipulation within the parameters of established software. As he asserts, ‘Once the design world has been set up, it still needs to be explored, played and mastered with finesse’. A veteran of architectural programming (he was the first architecture product manager for Autodesk, from 1985 to 1986), he reflects on the last two decades of development. Copyright © 2006 John Wiley & Sons, Ltd.
Process/drawing
Authors: Rea CEB 
Published: August 2006

AbstractWriting software is at the core of CEB Reas's artistic practice. The digital is his medium of choice rather than a means of manipulation. He reflects on the evolution of his work in software and why the history of using computers to produce visual images is largely an unrecorded one in the history of art, but why this might all be set to change as scripting takes on a new primacy in contemporary art. Copyright © 2006 John Wiley & Sons, Ltd.
Unified design: collaborative working at Arup Associates
Authors: Castle Helen 
Published: August 2006

AbstractGlobal telecommunication networks and the emergence of a new digital tool base have informed the reshaping of design practice worldwide. As discussed in detail in the next issue of AD, Collective Intelligence in Design (no 5, vol 76, 2006), ever‐evolving groups of designers, engineers, material scientists, manufacturers, contractors and even financiers are now working together across time zones and organisations. Though these current shifts have certainly facilitated a greater fluidity of exchange between disciplines, working across the professional setting is not a wholly new phenomenon. For over four decades, London‐based Arup Associates have collaborated in design as a team of architects and engineers, sitting within the greater corporate framework of the Arup Group. Declan O'Carroll, a principal at Arup Associates, tells Helen Castle how Arup Associates are now launching the Unified Design Unit that is set to recast Ove Arup's ethos of totality in design for the 21st century. Copyright © 2006 John Wiley & Sons, Ltd.