| Author (s): |
S. Göktürk, M. Mahramanhoglu and M. Tunçay
|
| Title: |
ADSORPTION OF ETHYL ACETATE FROM ALIPHATIC ALCOHOLS ON ACTIVATED CHARCOAL |
| Abstract: |
The adsorption equilibria of binary mixtures of ethyl acetate and aliphatic alcohols on activated charcoal were studied at 298 K. It was found that activated charcoal adsorbed ethyl acetate preferentially from all mixtures with aliphatic alcohols. The influence of the alkyl chain length of aliphatic alcohols on the adsorption of ethyl acetate was compared by means of composite and individual isotherms. The adsorption equilibrium data were analyzed on the basis of the Schay & Nagy Model
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| Keywords: |
Activated charcoal, adsorption, aliphatic alcohols,binary mixtures.
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| Year: |
2000
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| Initial page: |
1
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| Final page: |
12
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| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v8.n9.2000.4_2000.pdf |
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| Author (s): |
Radu Gropeanu, loan Panea and Teodora Panea
|
| Title: |
SYNTHESIS OF S-OXIDES AND S,S-DIOXIDES OF SOME 4-NITRO-AND 4-AMIN0-3-HYDROXY-10H-PHENOTHIAZINES AND -3H-PHENOTHIAZIN-3-0NES |
| Abstract: |
The S-oxides and S,S-dioxides of some 4-nitro- and 4-amino-3-hydroxy-1 OH-phenothiazines and -3H-phenothiazin-3-ones were obtained starting with 4-nitro-3H-phenothiazin-3-one (2) through selective reductions, followed by selective oxidations, 0- and N-acetylations and condensation with benzaldehydes. The chemical structure of compounds was determined using chemical and spectral (1H-NMR-, mass-, IR and UV-VIS spectroscopy) methods.
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| Keywords: |
3H-phenothiazin-3-on-S-oxides and -S,S-dioxides, 10Hphenothiazin-S-oxides and -S,S-dioxides, O- and N-acylation, selective reduction, selective oxidation, 1H-NMR spectra.
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| Year: |
2000
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| Initial page: |
13
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| Final page: |
24
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| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v8.n9.2000.16_2000.pdf |
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|
| Author (s): |
Luciano Endres and Carlos R Wolf
|
| Title: |
OPTIMIZATION OF ETHYLENE POLYMERIZATION CONDITIONS WITH METALLOCENE CATALYST USING EXPERIMENTAL DESIGN METHODOLOGY |
| Abstract: |
A study of ethylene polymerization was carried out using a 23 full factorial design in order to obtain a better understanding of the metallocene catalyst system. Three independent variables (reaction temperature, Al/Zr ratio, and ethylene pressure) were evaluated at two levels. The observed responses were catalytic yield, average molecular weight, polydispersity, melt flow rate, density, melting temperature, enthalpy of fusion, and crystallinity, the yield being of primary interest. The catalyst, co-catalyst and the solvent used were, respectively, Et(Ind)2ZrCl2, methylaluminoxane (MAO), and n-hexane. The statistical model was efficient in describing the effect of the variables on the yield and showed that the temperature was the variable of larger influence. The results permitted conclusions about the best polymerization conditions
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| Keywords: |
metallocene, ethylene polymerization, experimental design.
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| Year: |
2000
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| Initial page: |
25
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| Final page: |
35
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| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v8.n9.2000.28_2000.pdf |
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|
| Author (s): |
R. OLINESCU, D. O. CROCNAN, MARIA GREABU
|
| Title: |
THE ROLE OF FIBRINOGEN IN CORONARY HEART DISEASE AND ITS POSSIBLE DEPENDENCE ON ACTIVATED POLYMORPHONUCLEAR LEUKOCYTES |
| Abstract: |
Fibrinogen (FB), an acute-phase protein, is recognized as an independent risk factor in the plasma of patients with coronary heart disease (CHD). The plasma FB level is also significantly increased in inflammation and neoplasm. We performed an in vitro study showing that the chemiluminescence (CL) emission produced by zymosan-activated polymorphonuclear leukocytes (PMNL) was directly related to the concentration of FB, fibrinopeptide A, or FB-degradation products(FDP). Fibrin inhibited CL emission. We also found that the in vivo plasma levels of FB or FDP were significantly higher in the plasma of 1OO cardiac catheterized patients with CHD than in the plasma of the age and sex-matched controls. In 85% of the patients with CHD, both the plasma FB and the CL emission were significantly increased. In the other 15%, the plasma FDP level was higher than the FB level, however, the CL level was still higher than in the age and sex-matched controls. Activated PMNL may increase the plasma level of FDP as a consequence of enhanced enzyme-dependent degradation of FB. Our results indicate that the role of FB and independent risk factor in CHD depends on the level of activated polymorphonuclear leukocytes in the plasma
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| Keywords: |
fibrinogen, chemiluminescence, polymorphonuclear leukocytes, coronary heart disease, reactive oxygen species.
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| Year: |
2000
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| Initial page: |
37
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| Final page: |
43
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| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v8.n9.2000.39_2000.pdf |
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|
| Author (s): |
Maria Pleniceanu, Mihaela Mureseanu, Ion Ganescu and Olimpia Rusu
|
| Title: |
SPECTROPHOTOMETRIC STUDY OF THE BINARY SYSTEM Ru(III)-SOLOCHROME VIOLET RS AND THE DETERMINATION OF Ru(III) |
| Abstract: |
A simple and direct spectrophotometric method using solochrome violet RS has been developed for the determination of Ru(III). The molar absorptivity and the Sandell s sensitivity are calculated to be 104 L mol-1 cm-1 and 0.0101 μg cm-2, respectively. The effect of various parameters including time, pH, and added reactant volume has been studied Beers law is obeyed over the range 0.20- 7.07μg/mL of Ru(III). The method has been applied for the determination of Ru(III) in various synthetic and real samples.
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| Keywords: |
spectrophotometric determination, ruthenium, Solochrome Violet RS.
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| Year: |
2000
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| Initial page: |
45
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| Final page: |
51
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| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v8.n9.2000.46_2000.pdf |
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|
| Author (s): |
Paulo lrajara Borba Carneiro and Roberto Rittner
|
| Title: |
CARBON-13 NMR OF ALIPHATIC KETONES |
| Abstract: |
This work reports unpublished Carbon-13 NMR chemical shift data of three aliphatic ketones: 2-octanone, 2-nonanone, and 2-undecanone; and corrected data for 2-hexanone (C-4) and 2-decanone (C-1; C-2). The empirical substituent effects of the CH3CO group were determined more accurately and can be useful in correlation analysis.
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| Keywords: |
Carbon-13 NMR, chemical shift, aliphatic ketones.
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| Year: |
2000
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| Initial page: |
53
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| Final page: |
55
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| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v8.n9.2000.53_2000.pdf |
|
|
| Author (s): |
Dumitru Negoiu, Mirela Calinescu, Ana Emandi and Tudor Rosu
|
| Title: |
SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF N-(2-HYDROXY-1-NAPHTHALEN METHIN)-2- AMINOANILINE COMPLEXES |
| Abstract: |
N-(2-hydroxy-I-naphthalen methin)-2-aminoaniline (HL) forms stable complexes with chromium(III), of the type [CrL2]Cl, nickel(II), and copper(II), of the type [ML2] (M = Cu, Ni). Their structures have been characterized on the basis of elemental analysis, magnetic moment determinations, IR, electronic, and EPR spectral studies. Chromium(III) and copper(II) form distorted octahedral complexes, while nickel(II) forms typically a square-planar complex. Ligand field parameters have been calculated for these complexes
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| Keywords: |
Schiff bases; chromiurn(III), copper(II), nickel(II) complex compound.
|
| Year: |
2000
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| Initial page: |
57
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| Final page: |
69
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| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v8.n9.2000.56_2000.pdf |
|
|
| Author (s): |
Mirela Calinescu, Ana Emandi, Anca Nicolae and Lidia Paruta
|
| Title: |
MAGNETIC AND SPECTRAL STUDIES ON CHROMIUM(III), NICKEL(II) AND COPPER(II) COMPLEXES OF 4-HYDROXI-5-METHOXY ISOPHTHALDEHYDE BIS DIMETHYLHYDRAZONE |
| Abstract: |
A new hydrazone Schiff base, 4-hydroxy-5-methoxy isophthaldehyde bis dimethylhydrazone and its chromium(III), nickel(II), and copper(II) complexes have been synthesized and characterized by elemental analysis, molar conductance and magnetic moment determinations, infrared(IR), electronic and Electronic Paramagnetic Resonance(EPR) spectral studies. The complexes have distorted octahedral symmetry. Ligand field parameters have been calculated for Cr(III) and Ni(II) complexes on the basis of their electronic transitions, using the weak field approach and the strong-field approach
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| Keywords: |
hydrazones; chromium(III), nickel(II), copper(II) complexes.
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| Year: |
2000
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| Initial page: |
71
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| Final page: |
84
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| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v8.n9.2000.69_2000.pdf |
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|
| Author (s): |
Lavinel G. lonescua, Silvia Dani and Elizabeth Fatima de Souza
|
| Title: |
PHYSICAL CHEMICAL STUDIES OF THE AGGREGATION AND CATALYTIC PROPERTIES OF THE SURFACTANT METHYLDODECYLBENZYLTRIMETHYLAMMONIUM CHLORIDE (MDBTACL) |
| Abstract: |
The micellization of methyldodecylbenzyltrimethylammonium chloride (MDBTACL) in water was studied by means of surface tensiometry. The critical micellar concentration (CMC) was determined at 25°, 32° and 40°C and thermodynamic properties such as the free energy of micellization (∆G°mic), enthalpy (∆H°mic), and entropy (∆S°mic) of micellization were measured The CMC at 25°C was 1.12 x 10-2 M and the corresponding values of the thermodynamic parameters were: ∆G°mic = -2.66 kcal/mol; ∆H°mic = -0.82 kcal/mol and ∆S°mic = +6.17 e.u. Micelles of the surfactant MDBTACL were good catalysts for the alkaline hydrolysis of p-nitrophenyl diphenyl phosphate (NPDPP) with a maximum catalytic factor of approximately 60, comparable to that of CTAB. Typical activation parameters measured for 0.012 M surfactant and 0.005 M NaOH were: Ea = 8.5 kcal/mol; ∆H°≠ = 7.8 kcal/mol; ∆G°≠ = 19.6 kcal/mol and ∆S°≠ = -39. 3 e.u. The kinetic results were also analyzed in terms of the pseudo-phase ion-exchange models (PPIE) and showed that the model is applicable and gave reasonable fits.
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| Keywords: |
methyldodecylbenzyltrimethylammonium chloride; micellization; micellar catalysis; phosphate esters.
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| Year: |
2000
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| Initial page: |
85
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| Final page: |
95
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| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v8.n9.2000.83_2000.pdf |
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|
| Author (s): |
MARIA GREABU, D. 0. CROCNAN, R. OLINESCU
|
| Title: |
CHEMILUMINESCENCE, AN OUTSTANDING PHYSICOCHEMICAL METHOD |
| Abstract: |
Luminescence has been known since ancient times. However, consistent theories about the mechanisms involved in this process have been proposed only during the last few decades. The luminescence phenomenon is the result of the absorption of energy by atoms or molecules followed by their de-excitation, with photon emission in the visible part of the spectrum. The source of energy that leads to the excited species in bioluminescence and chemiluminescence is a chemical reaction that may or may not involve enzymes. This paper presents a short review of the present state of knowledge about chemiluminescence and discusses some of its applications in biology and medicine
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| Keywords: |
chemiluminescence, bioluminescence, phagocytosis, HPLC-detection, microbiology.
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| Year: |
2000
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| Initial page: |
97
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| Final page: |
112
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| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v8.n9.2000.94_2000.pdf |
|
|
| Author (s): |
Pedro de Magalhaes Padilha, Ariovaldo de Oiiveira Florentino, Fabricio Vieira de Moraes, Fabio Arlinda Silva, Cilene C. F. Padilha, Julio C. Rocha
|
| Title: |
PRE-CONCENTRATION OF Cd, Cu, Ni, Pb and Zn FROM FUEL ETHANOL AND NATURAL WATER SAMPLES BY SORPTION ON P-AMINOBENZOIC MODIFIED CELLULOSE AND SUBSEQUENT FLAME AAS DETERMINATION |
| Abstract: |
This work describes the synthesis of p-aminobenzoic modified cellulose (Cell-PAB), and the results of a study on the sorption and pre-concentration (using batch and in flow-through column methods) of Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II) in ethanol and aqueous medium. The sorption capacities for each metal ion were (in mmol.g-1); Ethanol medium: Cd(II) = 1.45, Cu(II) = 1.85, Ni(II) = 1.65, Pb(II)= 1.40 and Zn(II)= 1.50; Aqueous medium: Cd(II)= 1.30, Cu(II)= 1.80, Ni(II)= 1.50, Pb(II)= 1.20 and Zn(II)= 1.40. A recovery of almost 100% of the metal ions was obtained from ethanol as well as aqueous medium, the ions being sorbed in a column packed with 1 g of Cell-PAB, using 5 mL of 2.0 mol L-1 HCl solution as eluent. An enrichment factor of 45 (250 mL sample, 5 mL concentrate) was obtained by this preconcentration procedure. The sorption desorption procedure applied allowed the development of a preconcentration method for metal ions at trace level in fuel ethanol and natural water samples. After elution, the metal ions were determined by flame atomic absorption spectrometry.
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| Keywords: |
Fuel ethanol, water samples analysis, pre-concentration, p-aminobenzoic modified cellulose.
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| Year: |
2000
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| Initial page: |
113
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| Final page: |
124
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| Link: |
Acessar |
| DOI: |
10.48141/SBJCHEM.v8.n9.2000.110_2000.pdf |
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