Studia Universitatis Babeș-Bolyai Collection

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With a history of more than six decades (1955), Studia Universitatis Babeș-Bolyai (Studia UBB) is one of the leading academic journals in Romania.

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Start date: 2017End date: 2017

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Now showing 1 - 10 of 23
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    INFLUENCE OF THE Ni/Mg RATIO ON THE COLOUR OF SPINEL PIGMENTS PREPARED BY A MODIFIED SOL – GEL METHOD
    (STUDIA UBB CHEMIA. Published by Babeş-Bolyai University, 2017-03-30) Firuța GOGA; Roxana DUDRIC; Liliana BIZO; Alexandra AVRAM; Alexandru-Horațiu MARINCAȘ; Csaba VARHELY Jr.; Thomas DIPPONG
    This paper focuses on the synthesis and analysis of some spinel-structured, ceramic pigment nanopowders (Mg(1-x)NiₓAl₂O₄) using a modified sol – gel method. This study emphasizes the influence of the Ni/Mg ratio and that of the thermal treatment on the properties of the obtained powders. The behavior of the dried gels during calcination was studied by differential thermal analysis. The formation of the spinel structure after calcination was analyzed using x-ray diffraction. The colour of the powders was characterized by UV – VIS spectroscopy, determining the absorption spectra. In addition, the trichromatic coordinates were determined, and the corresponding pigment positions were fixed on the chromaticity diagram.
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    INVESTIGATION OF TITANIUM-DIOXIDE COATINGS ON MEMBRANE FILTRATION PROPERTIES
    (STUDIA UBB CHEMIA. Published by Babeş-Bolyai University, 2017-03-30) Ildikó KOVÁCS; Sándor BESZÉDES; Szabolcs KERTÉSZ; Gábor VERÉB; Cecilia HODÚR; Ibolya Zita PAPP; Ákos KUKOVECZ; Zsuzsanna LÁSZLÓ
    In this study, synthesized TiO₂ nanorods and commercial Aeroxide P25 TiO₂ nanoparticles were deposited on polyethersulfone (PES) membrane surfaces to compare their photocatalytic activity and effects on membrane surface and filtration properties. The catalysts were deposited on the membrane surface by physical deposition. The effect of the TiO₂ amount on the stability of the catalyst layer and its effect on membrane resistance in presence and absence of UV irradiation were investigated. 1.2 mg/cm² catalyst coverage proved to be a minimal appropriate coverage to prevent membrane damage during UV irradiation. The catalysts formed hydrophilic layers on the surface, and in case of both catalyst the surface free energy increased compared to the neat membrane. The photocatalytic activity and retention of the modified membranes were tested spectrophotometrically by using Acid Red1, azo dye.
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    INVESTIGATION OF THE EFFECT OF A HYBRID DRYING METHOD ON THE COLOR QUALITY OF NECTARINE SLICES AND ENERGY CONSUMPTION
    (STUDIA UBB CHEMIA. Published by Babeş-Bolyai University, 2017-03-30) Fatmagül Mutlu DEMIREL; Osman İSMAIL
    The main objective of a product quality study for drying agricultural products without causing distortion is to reduce the product moisture value to a final moisture value while expending the least energy and time. In the first stage of this study, nectarine slices were dried in a microwave and cabinet dryer under different drying conditions. Experiments in the microwave dryer were done at four different power levels: 90, 180, 360, and 600 W. Hot air drying was done at two temperatures, 50 and 70 °C, with a constant air velocity (2.0 m/s). In the second stage, after those experiments, the hybrid drying method were constructed based on the color parameter, and moisture ratio. In the hybrid drying method, hot air drying was carried out with microwave pretreatment. The most effective hybrid drying method in terms of optimal drying time, energy consumption, and color parameters was found to be at 180 W microwave power and 70 °C.
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    BENFOTHIAMINE ADMINISTRATION IN PATIENTS WITH DILATED CARDIOMYOPATHY AND ADVANCED HEART FAILURE WITH CHRONIC DIURETIC TREATMENT
    (STUDIA UBB CHEMIA. Published by Babeş-Bolyai University, 2017-03-30) Dana-Adriana ILUȚIU-VARVARA; Dan RĂDULESCU; Valer Ioan DONCA
    It is well known that long term administration of high dose loop diuretics in patients with heart failure, may in some cases aggravate the cardiac failure symptoms. Part of this effect may be due to thiamine depletion secondary to diuretics use. The aim of our present study was to assess whether administration of benfothiamine in patients with advanced congestive cardiac failure treated on long term with high dose loop diuretics, can prevent the alteration of heart failure.
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    SEASONAL EVOLUTION AND DEPTH VARIABILITY OF HEAVY METAL CONCENTRATIONS IN THE WATER OF FIRIZA-STRÎMTORI LAKE, NW OF ROMANIA
    (STUDIA UBB CHEMIA. Published by Babeş-Bolyai University, 2017-03-30) Thomas DIPPONG; Cristina MIHALI; Firuța GOGA; Elena CICAL
    The paper follows the spatial variability and seasonal evolution of the heavy metal content of the Firiza-Strîmtori Reservoir that is the main source of drinking water for Baia Mare city located in the northwestern part of Romania. Water samples were collected from 10 sampling points located along the median line of the lake at different depths (at surface, at 5 m, 10 m, 15 m and 20 m). The experiments were carried out in the winter, spring, summer and autumn of 2015. We determined the concentration – depth profiles, both for the heavy metals iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), cadmium (Cd), lead (Pb) and also for sodium (Na), potassium (K), calcium (Ca) and magnesium (Mg). We determined the concentrations of heavy metals by atomic absorption spectrometry. We found that concentrations of heavy metals increase with depth. Generally, the concentrations of heavy metals are within the legal limits for the water used as drinking water sources. Mathematical models with high correlation coefficients were obtained in the case of heavy metal concentrations depending on depth and also for the seasonality of heavy metals upload.
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    PREPARATION, CHARACTERIZATION, AND EVALUATION OF THE PHOTOCATALYTIC EFFECT OF α-Fe₂O₃/SAPO-34 IN THE ELIMINATION PROCESS OF THE ANTI-CANCER DRUG DOXORUBICIN FROM AQUEOUS SOLUTION
    (STUDIA UBB CHEMIA. Published by Babeş-Bolyai University, 2017-03-30) Mohammad Hosein BIGTAN; Kazem MAHANPOOR
    In this investigation, α-Fe₂O₃/SAPO-34 nano-structure were synthesized and characterized by XRD, SEM and FT-IR techniques. Morphologically, the shape of α-Fe₂O₃/SAPO-34 nanoparticles is close to spherical nanoparticles with an average particle size of 93 nm determined by Debye-Scherrer equation. The photocatalytic activity of α-Fe₂O₃/SAPO-34 nanostructure was investigated through the degradation of doxorubicin, an anti-cancer drug using a batch reactor under UV-C irradiation and H₂O₂ as oxidant. The effect of various factors including drug concentration, catalyst dosage, pH and H₂O₂ concentration on the degradation yield were investigated. The results showed that optimum conditions were: Initial concentration of DOX = 20 ppm, pH = 8, amount of α-Fe₂O₃/SAPO-34 = 150 mg/L, and H₂O₂ concentration 4 mol/L.
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    UNMODIFIED AND GOLD-MODIFIED SEMICONDUCTOR CATALYSTS FOR SOLAR LIGHT ASSISTED PHOTODEGRADATION OF CRYSTAL VIOLET
    (STUDIA UBB CHEMIA. Published by Babeş-Bolyai University, 2017-03-30) Zsigmond PAPP
    Different unmodified and modified semiconductor photocatalysts were used for the complete decolorization of an unbuffered crystal violet solution. The decolorization efficiency of commercially available ZnO and TiO2 (anatase nanopowder) was compared with those of newly prepared gold-modified ZnOs (Au/ZnOs). Two Au/ZnOs were prepared from pure ZnO powder through deposition of gold by direct current (DC) sputtering. The morphological characterization of the Au/ZnOs was done with the aid of scanning electron microscopy. ZnO-based catalysts show significantly higher decolorization power in comparison with TiO2. Au/ZnOs show slightly higher activity than unmodified ZnO.
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    SYNTHESIS OF THREE NEW BIFUNCTIONAL GLUCOSE-THIOUREA ORGANOCATALYSTS AND THEIR APPLICATION IN ASYMMETRIC MICHAEL ADDITION
    (STUDIA UBB CHEMIA. Published by Babeş-Bolyai University, 2017-03-30) Sándor NAGY; Petra KOZMA; Péter KISSZÉKELYI; Dóra BEZZEGH; Péter HUSZTHY; József KUPAI
    Three new glucose-based asymmetric bifunctional organocatalysts containing a 6-aminopyridyl or a 6-methylpyridyl or a cinchona unit were synthesized. Asymmetric Michael addition of pentane-2,4-dione to β-nitrostyrene was catalyzed successfully by these catalysts. In case of the cinchona based glucose-thiourea derivate the S enantiomer of the corresponding Michael adduct was formed with moderate enantiomeric excess in three different solvents.
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    IDENTIFICATION OF MASS TRANSFER PARAMETERS FOR ROCK SALT DISSOLUTION IN A PLUG FLOW SYSTEM
    (STUDIA UBB CHEMIA. Published by Babeş-Bolyai University, 2017) Szabolcs FOGARASI; Melinda NAGY; Florica IMRE-LUCACI; Arpad IMRE-LUCACI
    Considering the particularities of rock salt solution mining, the current paper aims to determine the mass transfer parameters for rock salt dissolution in a plug flow system. The influence of crucial operating parameters such as flow rate and channel depth on the mean driving force, volumetric mass transfer coefficient and extraction yield was evaluated. It was found that flow rate increase intensifies the dissolution process leading to a more rapid dissolution of the rock salt deposit. Similar effect was noticed in the case of flow channel depth increase which leads to higher mass transfer area, increasing the amount of dissolved salt from the rock salt deposit.
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    INVESTIGATING THE IMPACT OF SOILS’ PHYSICOCHEMICAL COMPOSITION ON CHLORSULFURON PEDOSPHERIC SORPTION
    (STUDIA UBB CHEMIA. Published by Babeş-Bolyai University, 2017-03-30) Khuram Shahzad AHMAD
    Chlorsulfuron (1-(2-chlorophenyl) sulfonyl-3-(4-methoxy-6-methyl-1, 3, 5- triazin-2-yl)), a Sulfonyl herbicide was investigated for its sorption behaviour in soils from various geographical locations. The results, fitting Freundlich and Linear equations, depicted a C type curve. Linear distribution coefficient value (Kd) spanned in a range of 8.2-23.0 µg/ml while Freundlich distribution coefficient value (Kf) was found to be 7.06 -17.41 µg/ml. Low Gibbs free energy values (-14.9 to -16.0 kJ/mol) are indicative of physisorption process. The regression and correlation analysis depicted pH to be negatively correlated (r=-0.936) while organic matter and organic carbon to be positively correlated with Kd (r=0.989 and r=0.988 respectively). However the soil texture rendered positive correlation with clay (r=0.897) and negative correlation with sand and silt (r=-0.990 and r=-0.820 respectively). Desorption hysteresis coefficient (H), in all four soil was found to be less than 1 (0.44 to 0.62). Results have been statistically evaluated by ANOVA and the accuracy of fit has been calculated by plotting residual graphs in Minitab. This study is a milestone for further investigation based on Chlorsulfuron degradation and mobility patterns.
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