bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis, spectral description, and lipophilicity parameters determination of phenylcarbamic acid derivatives with integrated N-phenylpiperazine moiety in the structure
Authors: Malík I. , Sedlárová E. , Csöllei J. , Andriamainty F. , Kurfürst P. , Vančo J.
Published: August 2006

The phenylcarbamic acid derivatives with N-phenylpiperazine moiety in the molecule have been prepared. The structure has been confirmed by elemental analysis, IR, 1H NMR, and mass spectral data. For the prepared set of the compounds the lipophilicity parameters have been determined. The experimentally obtained lipophilicity parameters have been correlated with theoretical entries obtained by different computer programs based on the neural network and fragmental methods.
New methods in synthesis of acetylcholinesterase reactivators and evaluation of their potency to reactivate cyclosarin-inhibited AChE
Authors: Musílek K. , Lipka L. , Račáková V. , Kuča K. , Jun D. , Dohnal V. , Doležal M.
Published: August 2006

Nine potential AChE reactivators were synthesized using modification of currently known synthetic pathways. Their potency to reactivate AChE inhibited by cyclosarin nerve agent was tested in vitro. According to the previous results, 1,4-bis(2-hydroxyiminomethylpyridinium)butane dibromide seems to be the most potent AChE reactivator. The reactivation potency of these compounds depends on structural factors such as presence of quaternary nitrogens, length of the linking chain between both pyridinium rings, and position of the oxime moiety at the pyridinium ring.
Furan-containing thiacyanine analogs and their antimicrobial activity
Authors: Kortišová I. , Foltínová P. , Halgaš J.
Published: August 2006

Condensation of quaternary 2-methylbenzothiazolium bromides with 5-(dialkylamino)furan-2-carbaldehydes afforded a series of new thiacyanine analogs. The compounds exhibit significant activities against several bacterial, yeast, and mould strains. Derivatives with dipropylamino substituents showed higher inhibitory effects than those with cyclic secondary amino groups. Hence, the biological activity may have been influenced by the lipophilicity of the compounds. The effect on growth and on the plastid system of the unicellular flagellate Euglena gracilis was also studied.
Synthesis and biological activity of new 1,3,4-thiadiazole derivatives
Authors: Aly A. , El-Sayed R.
Published: August 2006

The aminothiadiazole (II) on treatment with aromatic aldehydes yielded Schiff bases, which cyclized to thiazolidinone derivatives by reaction with thioglycolic acid. Reaction of II with phenyl isocyanate and phenyl isothiocyanate afforded the carbamide and carbothiamide derivatives, respectively, which on reaction with malonic acid in acetyl chloride gave barbituric and thiobarbituric acid derivatives. However, reaction of carbon disulfide and methyl iodide with II gave dithiocarbamidate derivative which on treatment with ethylenediamine or o-phenylenediamine gave the condensed N-imidazolylthiadiazolylamine derivatives.
Synthesis and characterization of oligosalicylaldehyde-based epoxy resins
Authors: Sahmetlioglu E. , Mart H. , Yuruk H. , Surme Y.
Published: August 2006

The synthesis of a new epoxy resin of oligosalicylaldehyde by the reaction with epichlorohydrin is reported. New resin’s epoxy value and chlorine content were determined and found to be 25% and 1%, respectively. The characterization of the new resin was instrumented by FTIR, 1H NMR, scanning electron microscopy, and thermal gravimetric analyses. TGA results showed that the cured epoxy resin has a good resistance to thermal decomposition. The mass losses of cured epoxy resin were found to be 5%, 10%, 50% at 175°C, 240°C, and 400°C, respectively. On the curing procedure the resin was cured with polyethylenepolyamine at 25 °C for 8 h and 100°C for 1.5 h. The FTIR spectrum of new epoxy resin gave the peak of oxirane ring at ṽ = 918 cm−1.
Extracellular polysaccharides produced by acapsular mutant of Cryptococcus laurentii
Authors: Dudíková J. , Kolarova N.
Published: August 2006

Heterogeneous extracellular polysaccharide galactoxylomannan has been isolated from the culture medium of the acapsulated mutant Cryptococcus laurentii 17-3-6 as the main extracellular polysaccharide (90%). Size-exclusion chromatography of precipitated polysaccharides afforded two molecular fractions with molecular mass 75 kDa and 20 kDa. Mannose, galactose, glucose, and xylose ratios were 1.00: 1.16: 0.04: 0.88 and 1.00: 0.25: 0.07: 0.24, respectively.
Liquid chromatography of synthetic polymers under limiting conditions of insolubility. I. Principle of the method
Authors: Berek D.
Published: August 2006

A novel liquid chromatographic procedure is presented. It is based on differences in the transport velocities of the fast-moving, pore-excluded macromolecules and slow-progressing, pore-permeating small molecules of an auxiliary liquid. A barrier of small molecules selectively decelerates certain kind of macromolecules while other kind remains unhindered. As a result, polymers of different nature are efficiently separated. In this new approach, the barrier is formed by a zone of a non-solvent injected immediately before the sample solution. The resulting method is denoted liquid chromatography under limiting conditions of insolubility.
Transport velocities of different particulate materials in pneumatic conveying
Authors: Hartman M. , Phořelý M. , Trnka O.
Published: August 2006

Particle horizontal transport and vertical entrainment of widely different materials (silica sand, alumina, ceramsite, dry sludge, and wood shreds) are explored by experimental measurements. Experiments have been performed with two very narrow fractions of solids (0.315–0.50 mm and 1.4–1.6 mm) on a laboratory setup. Simple empirical correlations are proposed in terms of the Reynolds and Archimedes criteria for the commencement of the horizontal conveying as well as the vertical entrainment of particles in pipelines.
Chemistry for the design and better understanding of cement-based materials and composites
Authors: Drábik M. , Gáliková L’. , Slade R.
Published: August 2006

Macrodefect-free (MDF) materials are one example of “hot topics” in the field of cement-based materials and composites exerting new possibilities of the exploitation of added value. These are formed through cross-linking reactions of atoms at the interfaces of cement grains and functional polymers, when medium pressure and twin-rolling procedure are applied. The MDF-relevance of the system of Portland cement + polyphosphate is reported, together with optimal synthesis conditions and limiting rules. The chemistry knowledge about MDF materials has been shown critical for both procedure design and exploitation. Chemical shifts in both 27Al and 31P MAS NMR spectra confirm Al(6)—O—P(4) cross-linking in virgin probes and indicate secondary hydrolysis during moisture uptake in domains free of cross-links. Thermogravimetric identification of the contents of hydrated and cross-linked phases in virgin and in moisture-attacked MDF probes displays that moisture uptake is accompanied by an increase in content of cementitious hydrates and CaCO3. The key phenomena governing the moisture sensitivity/resistance are the density and compactness of interfacial Al(6)—O—P(4) cross-links vs. the access of the moist environment to the unreacted cement residue.
Surface modifications of natural clinoptilolite-dominated zeolite for phenolic pollutant mitigation
Authors: Chmielewska E. , Pilchowski K.
Published: August 2006

A novel carbonized clinoptilolite-rich tuff was studied for phenol removal from water. Zeolite sample carbonization was accomplished in a plasmachemical reactor (pyrolytic chamber) using several types of waste, here specifically waste vegetable residues and starch. Phenol adsorption experiments were performed in the batch system. An industrial activated charcoal and a clinoptilolite-rich tuff hydrofobized with an organic ammonium base were used as the related materials to compare phenol removal efficiency.
Trace analysis of lead by anodic stripping voltammetry with collection at interdigitated microelectrodes in small-volume samples
Authors: Rievaj M. , Dovalovská Z. , Bustin D.
Published: August 2006

A simple and sensitive electroanalytical method was developed for microvolume trace elements determination. Commercially available interdigitated microelectrodes (IDA) from ALS Japan Inc. based on a thin carbon film technology were used. Anodic stripping voltammetry with collection at IDA was applied. Carbon IDA microbands were coated with a pre-deposited mercury film for better performance. The method with this sensor enables analysis of some heavy metals in total sample volumes as small as 0.05 cm3. The method was applied to Pb in blood samples determination by a standard addition method.
Investigation of the solid samples evaporation from the auxiliary DC arc discharge in the atomic emission spectroscopy
Authors: Ružičková S. , Koller L. , Matherny M.
Published: August 2006

Efficiency of the suggested tandem technique of Marinković burner was studied in terms of the influence of the PC-controlled DC arc of the different intensities (10 A, 15 A, 20 A, 25 A) on the evaporation process. Higher intensities than 25 A did not allow to use the given experimental equipment since they cause plasma instability and periodic plasma quenching. The suggested method was evaluated by the determination of the half (t 50%) and total (t 100%) evaporation time and by determination of the signal/background ratio for the chosen elements (Al, Ca, Cr, Fe, Mg, Ni, Si, and V) in the model graphite matrix.
Determination of bioavailable iron in noncontaminated Slovak soils by flame atomic absorption spectrometry
Authors: Barteková J. , Žemberyová M. , Bajčan D. , Vyšinská D.
Published: August 2006

A method for the extraction of bioavailable iron from soils from various parts of Slovakia using a buffered diethylenetriaminepentaacetic acid (DTPA) solution was utilized. The extractant consists of 0.005 mol dm−3 DTPA, 0.1 mol dm−3 CaCl2, and 0.1 mol dm−3 triethanolamine with pH of 7.3. DTPA was selected as the chelating agent because it can effectively extract micronutrient metal, iron. Distribution of iron in the horizons of various types of soils with respect to bioavailable iron was evaluated. The bioavailable iron in the extracts was determined by flame atomic absorption spectrometry. The calibration standards were prepared in the same surroundings as the extracts. Comparing to the average of 2.7–3.7 % total iron contents in Slovak soils, the available amounts of iron represent in average only very small amounts, approximately 0.3 % in comparison to total amounts.
Determination of technetium-99 in soils and radioactive wastes using ICP-MS
Authors: Bartošová A. , Rajec P. , Klimeková A.
Published: August 2006

Three methods have been used for the determination of 99Tc in soils and solid radioactive wastes using 99mTc as a yield monitor. In the method one and three the samples were leached in low concentrated nitric and sulphuric acid. Many contaminants were then co-precipitated with Fe(OH)3 in alkali media and Tc in the supernatant was separated using anion-exchange extraction chromatography. There were made also some studies how to improve the chemical recovery of 99mTc in the process of chromatography. In the method two the sample was ashed and then leached in 8 mol dm−3 HNO3 and after iron precipitation, technetium was separated on chromatographic column. The chemical recovery of 99mTc was optimized in the process of chromatography and leaching. Typical recoveries of technetium determined with 99mTc tracer for all these methods were in the range 39 %–87 %.

The 99Tc activity was measured using proportional low-background beta detector after one week of staying to allow decay of 99mTc activity. 99Tc was also determined by the non-radiometric method using inductively coupled plasma mass spectrometer.
Spectrophotometric determination of nickel(II) in different samples by complexation with some triazolylazo dyes
Authors: Khedr A.
Published: August 2006

A new sensitive spectrophotometric method for the determination of nickel(II) with 3-(2-hydroxy-5-acetyl-(L1),-5-ethoxycarbonyl-(L2),-5-methyl-(L3),-5-formyl-(L4),-5-bromophen-1-ylazo)-1,2,4-triazole (L5), and 3-(2,4-dihydroxyphen-1-ylazo)-1,2,4-triazole (L6) in aqueous media containing 40 vol. % methanol has been developed. The method is based on the formation of stable coloured Ni(II) complexes with stoichiometric ratios 1: 1 and 1: 2 (n(M): n(L)). Linear calibration graphs are obtained up to 7.04 µg cm−3 of nickel(II) under optimum conditions attained from investigation of complex formation. The absorption maxima varied from 485 nm to 545 nm and the molar absorptivities ranged from 0.84 × 104 to 4.65 × 104 dm3 mol−1 cm−1 for 1: 1 and 1: 2 (n(M): n(L)) complexes with varying the substituent on the phenolic ring. The optimum ranges for the direct determination of nickel(II) (Ringbom) and the stability constants of the formed complexes are determined. The developed method was applied to the spectrophotometric determination of nickel(II) in some samples with satisfactory results.
Complexes of biologically important ligands. I. Ternary complexes of nickel(II) comprising 1,10-o-phenanthrolineazosulfonamide derivatives and alkyldithiophosphates
Authors: Aly A. , Awad I. , Abd El-Mottaleb M. , Abd El-Aal K.
Published: August 2006

5-[p-(R-Sulfonyl)phenylazo]-1,10-o-phenanthroline (L) and its octahedral complexes of the type [Ni(R2dtp)2(L)] (where R2dtp = diethyl-or dipropyldithiophosphate) with the core NiN2S4 have been prepared and characterized by spectral, magnetic, and thermogravimetric methods. The thermal decomposition mechanism of the compounds was proposed and the kinetic parameters of decomposition were calculated making use of the Coats—Redfern and Horowitz—Metzger equations.
Effects of Cd(II) and Zn(II) complexes with bioactive ligands on some photosynthesizing organisms
Authors: Král’ová K. , Masarovičová E. , Lešíková J. , Ondrejkovičová I.
Published: August 2006

The effects of the complexes of the type M(L)2(nia)2 (M = Cd or Zn; L = acetate (ac) or NCS−; nia = nicotinamida) on reduction of chlorophyll content in suspensions of Chlorella vulgaris and inhibition of photosynthetic electron transport in spinach chloroplasts were investigated. The inhibitory effects of the studied compounds depended on the central metal atom as well as on the structure of L ligands. In general, the toxicity of M(NCS)2(nia)2 was higher than that of M(ac)2(nia)2 and the compounds containing cadmium were more toxic than those with Zn.

Dry mass of plants cultivated in the presence of the studied complexes (c = 100 µmol dm−3) showed a decrease related to control plants. The uptaken metal (Cd or Zn) was accumulated mainly in the roots. In general, application of M(ac)2(nia)2 compounds led to higher accumulated metal content in dry mass of plant organs (in mg g−1) related to M(NCS)2(nia)2 administration. In plants treated with Zn(NCS)2(nia)2 lower content of essential metals Mn and Cu was found than in those treated with Zn(ac)2(nia)2.

Toxic effects of the studied M(L)2(nia)2 compounds could be caused by exchange of their ligands with potential “biotic S-, O-, and N-donor ligands” occurring in the plant cells.
Efficiency of a fixed-bed and a gas-lift three-column reactor for continuous production of ethanol by pectate-and alginate-immobilized Saccharomyces cerevisiae cells
Authors: Valach M. , Navrátil M. , Horváthová V. , Zigová J. , Šturdík E. , Hrabárová E. , Gemeiner P.
Published: August 2006

Ethanol-tolerant and thermo-tolerant yeast strain Saccharomyces cerevisiae C11-3 cells immobilized in calcium pectate and calcium alginate gels were used for ethanol fermentation in a three-reactor system with a gradient temperature control. The fermentation process has been tested in a fixed-bed and a gas-lift arrangement. The gas-lift system was more efficient due to a better mass transport between the phases. Abrasion was more evident in calcium alginate particles, while calcium pectate beads were not significantly damaged. Two different concentrations of alginate were tested and calcium pectate gel was demonstrated to be more suitable as an immobilization material in comparison with calcium alginate due to its mechanical resistance and favourable diffusion parameters, providing an ethanol production of more than 7.5 g dm−3 h−1 over a period of 630 h.
Calibrationless determination of electroactive species using chronoamperograms at collector segment of interdigitated microelectrode array
Authors: Jenčušová P. , Tomčík P. , Bustin D. , Rievaj M. , Dovalovská Z.
Published: August 2006

The possibility of calibrationless chronoamperometric determination is described using a pair of individually addressable and diffusion layers interacting segments of interdigitated microelectrode array (IDA). It utilizes dual voltammetric mode where the first segment is polarized with potential corresponding to the limiting current of determined species electrode reaction and the second segment is polarized with potential corresponding to the opposite electrode reaction limiting current. Time at which the current of the collector segment reaches one half of the steady state is hyperbolically dependent on the diffusion coefficient of analyte. The determination of diffusion coefficient allows direct calculation of bulk concentration avoiding calibration with a standard solution. The equipment for measuring of fast response of IDA arrays in dual mode has been developed using a bipotentiostat connected with A/D transducer. It allows less than 1 ms sampling period for ultrafast registration of chronoamperogram. The method was tested and validated with [Fe(CN)6]4−, [Ru(NH3)6]Cl3, and ferrocene model samples using various types of IDA arrays.
The β-carotene dilemma: ESR study with coordinated peroxyl radicals
Authors: Tkáč A. , Scott G.
Published: August 2006

The apparently unpredictable behaviour of β-carotene in the supplementation of the diet of smokers is discussed in the light of the reactions of peroxyl radicals with β-carotene in the absence of oxygen. The decay of tert-butylperoxyl radicals in the presence of β-carotene was studied at ambient temperature in non-polar solvents by ESR spectroscopy. The primary reaction in the absence of oxygen is interpreted as a spin-trapping effect of a peroxyl radical by β-carotene producing an intermediate labile free radical, which disappears after recombination with a second tert-butylperoxyl radical. The result is the transformation of β-carotene to a diamagnetic compound with two peroxy bonds. In the presence of chelating transition metals with unpaired d-electrons as electron donors the peroxy group of the oxidized β-carotene can be split to alkoxyl free radicals. The primary attack of tert-butylperoxyl radicals is completely inhibited in the presence of vitamin E followed by production of free aryloxy radicals and the presence of oxygen has no significant effect on this reaction. Spin-trapping of peroxyl radicals by the double bond of vitamin A leads to its oxidation in the absence of vitamin E.

Transition metal ions such as Co, Cr, Fe, and Mn, known to be present in the aerosol of cigarette smoke, homolyse the peroxyl bonds of peroxidised β-carotene, which results in cell damage.
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

The 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

The 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

Some 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

A 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

The 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

Substituted 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

1,3-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

The 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

Complex 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

The 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

2H-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

The 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

The 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

A 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

A 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

The 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

Concentration 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

The 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

The 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

The 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

Various 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

The 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

New 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

Malcolm 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

Writing 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

Global 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.
Jordan Mozer & Associates: New American narratives
Authors: Watson Howard
Published: August 2006

Jordan Mozer is a designer of surprising contradictions. Having pursued a specifically American form of storytelling through his designs for the likes of Bellagio in Las Vegas and the Hudson Club in Chicago, he despises the impulse towards homogeneity in the US. He begins all designs with a service plan, yet pursues the expressionistic potential of architecture. Howard Watson provides insights into the work of a designer who has proved as successful in Germany as in his hometown of Chicago. Copyright © 2006 John Wiley & Sons, Ltd.
Flexibility analysis: Taking into account fullness and accuracy of plant data
Authors: Ostrovsky G. M. , Volin Yu. M.
Published: August 2006

The modern foundations of flexibility analysis were developed in the 1980s by Grossmann and co‐workers. They formulated the approaches to solve the main problems of flexibility analysis, namely, the feasibility test, flexibility index, and two‐stage optimization problem (TSOP). All these formulations are based on the supposition that during the operation stage there is enough plant data to accurately determine all uncertain parameter values. However, in practice, this assumption is likely to be untrue. To deal with this problem, the feasibility test and TSOP were extended to account for the possibility of accurately estimating only some of the uncertain parameters. However, these extensions have a drawback. They do not take into account all the data that are available at the operation stage. A formulation is discussed that will remove this drawback of the TSOP. The formulation requires working out a modification of the split and bound approach, which had been developed for solving the TSOP. Then, two computation experiments are performed to demonstrate the advantage of taking the additional plant data from the operation stage into account. © 2006 American Institute of Chemical Engineers AIChE J, 2006
1,1′‐Dimethylvanadocene α‐amino acid complexes: synthesis, characterization and antimicrobial behavior toward Escherichia coli B
Authors: Hana Paláčková , Jaromír Vinklárek , Jana Holubová , Božena Frumarová , Ivana Císařová , Milan Erben
Published: August 2006

Eight water‐soluble 1,1′‐dimethylvanadocene amino acid complexes have been prepared via the reaction of (MeCp)2VCl2 (2) with one equivalent of amino acid (aa) in water affording [(MeCp)2V(aa)]Cl, where aa is glycine (3), L‐alanine (4), L‐valine (5), L‐leucine (6), L‐isoleucine (7), L‐phenylalanine (8), L‐histidine (9) and L‐tryptophane (10). All prepared complexes have been characterized by EPR, IR and Raman spectroscopy, elemental analysis and mass spectrometry. Molecular structures of [(MeCp)2V(ala)]BPh4·CH3OH (11), [(MeCp)2V(leu)]PF6 (12) and [(MeCp)2V(ile)]PF6 (13) were determined by X‐ray diffraction analysis. Cytotoxic properties of complexes 2–10 were investigated toward Escherichia coli B and compared with analogical unsubstituted vanadocene compounds (1, 14–21). The results showed that 1,1′‐dimethylvanadocene amino acid complexes have identical or slightly higher antiproliferative activity then their unsubstituted analogs. Copyright © 2006 John Wiley & Sons, Ltd.
The reduction of Ag(I) by α‐silylamines R2NCH2SiX3
Authors: Lazareva Nataliya F. , Vakul'skaya Tamara I. , Albanov Alexander I. , Pestunovich Vadim A.
Published: August 2006

The introduction of the organosilicon substituent into the α‐position of an amino group results in cardinal change of the amine reactivity irrespective of the coordination state of silicon. Amines R2NCH2SiX3 [R = Me, Et, PhCH2, CH2SiX3; SiX3 = SiMe3, Si(OEt)3, Si(OCH2CH2)3N] easily react with AgNO3, to give the corresponding ammonium salts (R2NH+ CH2SiX3)·NO3−. At the same time, Ag(I) is reduced to Ag(0). The interaction of N‐methyl‐N,N‐bis(silatranylmethyl)amine with AgNO3 has been investigated by EPR spectroscopy. It was proven that the reaction involved a single electron transfer stage with the formation of cation radical of this amine. A mechanism of the reaction is proposed. Copyright © 2006 John Wiley & Sons, Ltd.