Chemistry Journal of Moldova

Physical chemistry and chemical physics

SYNTHESIS AND CHARACTERIZATION OF CdSe COLLOIDAL QUANTUM DOTS IN ORGANIC SOLVENT

Author(s):

Ion Geru, Olga Bordian, Constantin Loshmansky, Ion Culeac, Constantin Turta


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2014 Volume 9, no.1
Pages: 128-131
Keywords: colloidal quantum dots, semiconductor, cadmium selenide, nanocrystals, photoluminescence
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Abstract (PDF)

DOI:
dx.doi.org/10.19261/cjm.2014.09(1).17

Graphical Abstract:
 In this paper we present experimental results on preparation and characterization of colloidal CdSe quantum dots in organic solvent. CdSe QDs were synthesized following a modified literature method.
CdSe QDs were isolated by adding acetone to the cooled solution followed by centrifugation.
CdSe QDs have been characterized by UV-Vis absorption and photoluminescent (PL) spectroscopy. The average CdSe particles size estimated from the UV-Vis absorption spectra was found to be in the range 2.28-2.92 nm which is in good agreement with PL measurements. 

Downloads: 92

A REVIEW OF THE BIOGENESIS OF IRON NANOPARTICLES USING MICROORGANISMS AND THEIR APPLICATIONS

Author(s):

Lilia Anghel, Gheorghe Duca


Field: Physical chemistry and chemical physics
Type: Review
Issue: 2013 Volume 8, no.2
Pages: 32-41
Keywords: nanoparticles, iron, microorganisms, biological synthesis, biomedical applications
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DOI:
dx.doi.org/10.19261/cjm.2013.08(2).03

Graphical Abstract:
Iron-based nanoparticles have gained a lot of attention due to their properties which offer a broad range of biomedical and industrial applications. Traditional methods of synthesis of iron nanoparticles strongly influence their properties and limit their applicability. Recently, there has been a growing interest in the development of biological routes of syntheses of iron nanoparticles as the resulting particles have structural characteristics required by biomedical field. The mechanism for the synthesis of iron-based nanoparticles by microorganisms and its current limitation are presented.



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THE INFLUENCE OF THE POROUS STRUCTURE OF LOCAL ACTIVATED CARBONS ON THE IMMOBILIZATION OF THE CONGO RED DYE AND VITAMIN B 12

Author(s):

N. Timbaliuc, T. Lupascu


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2013 Volume 8, no.1
Pages: 90-94
Keywords: activated carbons, adsorption, mesopore volume, Congo Red, vitamin B12.
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Abstract (PDF)

DOI:
dx.doi.org/10.19261/cjm.2013.08(1).11

Graphical Abstract:
The adsorption properties of activated carbons, obtained from local raw materials (nut shells, peach and plum stones), towards Congo Red and vitamin B12 have been studied.  The values of adsorption of these marker-substances are in direct correlation with the structural characteristics of the studied samples of activated carbons, in particular, with their mesopore volume.

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NONEXPERIMENTAL SCREENING OF THE WATER SOLUBILITY, LIPOPHILICITY, BIOAVAILABILITY, MUTAGENICITY AND TOXICITY OF VARIOUS PESTICIDES WITH QSAR MODELS AID

Author(s):

O.G. Kolumbin, L.N. Ognichenko, A.G. Artemenko, P.G. Polischuk, М.A. Kulinsky, Е.N. Мuratov, V.E. Kuz’min, V.A. Bobeica


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2013 Volume 8, no.1
Pages: 95-100
Keywords: pesticides, toxicological analysis, QSAR, lipophilicity, RF method.
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Abstract (PDF)

DOI:
dx.doi.org/10.19261/cjm.2013.08(1).12

Graphical Abstract:
In our study the dataset containing 489 pesticides and their active substances of different classes of organic compounds was used for analysis. For compounds of analyzed dataset the values of lipophilicity, water solubility, toxicity, bioavailability and mutagenicity were predicted by developed QSAR models. The most environmentally hazardous substances were identified using prediction of QSAR models for pesticides. The satisfactory coincidence between the experimental values of investigated properties and their predicted values by QSAR models was obtained (coefficient of determination in the range 83-94 %).

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INTERACTION OF ALBUMIN AND IMMUNOGLOBULIN G WITH SYNTHETIC HYDROXYAPATITE

Author(s):

E. Pylypchuk, V. Mishchenko and T. Yu. Gromovoy


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2012 Volume 7, no.2
Pages: 143-146
Keywords: MALDI-ToF, X-ray phase analysis, albumin, immunoglobulin G, hydroxyapatite, interaction.
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Abstract (JPEG)

DOI:
dx.doi.org/10.19261/cjm.2012.07(2).02

Graphical Abstract:
 It was shown by X-ray phase analysis, IR spectra analysis and MALDI-ToF mass spectrometry methods that interaction of synthetic hydroxyapatite with a solution of immunoglobulin G leads to its partial dissolution due to leaching from the surface of calcium triphosphate which, in our opinion, forms complexes with immunoglobulin G.

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COMPARATIVE KINETICS STUDY OF THE THERMAL AND THERMO-OXIDATIVE DEGRADATION OF A POLYSTYRENE-CLAY NANOCOMPOZITE BY TGA AND DSC

Author(s):

Ion Dranca, Nicon Ungur,Tudor Lupascu, Oleg Petuhov


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2010 Volume 5, no.2
Pages: 68-72
Keywords: degradation; fire resistance; nanocomposites; thermogravimetric analysis (TGA); differential scanning calorimetry (DSC).
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Abstract (JPEG)

DOI:
dx.doi.org/10.19261/cjm.2010.05(2).09

Graphical Abstract:
The methods of thermogravimetry (TGA) and differential scanning calorimetry (DSC) have been used to study the thermal and thermo-oxidative degradation of polystyrene (PS) and a PS-clay nanocomposite. An advanced isoconversional method has been applied for kinertic analysis. Introduction of the clay phase increasers the activation energy and affects the total heat of degradation, which suggests a change in the reaction mechanism. The obtained kinetic data permit a comparative assessment of the fire resistance of the studied materials.

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METALLIC COMPOUNDS IN THE PHASE OF THE RETICULATED IONIC POLYMERS

Author(s):

Vasilii Gutsanu, Constantin Turta, George Filoti


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2010 Volume 5, no.2
Pages: 73-82
Keywords: ion exchangers, Mossbauer spectra, iron, superparamagnetic, complexes, polymer phase.
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Abstract (JPEG)

DOI:
dx.doi.org/10.19261/cjm.2010.05(2).10

Graphical Abstract:
Using the Mossbauer spectroscopy and other physical methods it was demonstrated the presence of different iron compounds like β-FeOOH, α-Fe2O3, and jarosite mineral type compounds: (R4N,H3O)[Fe3(OH)6(SO4)2] or coordination modes: {RCOO-Fe(L4)-OOCR}1+, {R-CO2=Fe(X2)=O2C-R}n, {R-COO-Fe(X4)-OOC-R}n, and {(-NCH2CH2N-)= Fe(X2) =(-NCH2CH2N-)}, where X= H2O, OH-, SO42-., n= from 3- to 1+ in the ion-exchange resins (KU-2, AN-31, AV-17, Varian – AD, EDE-10P) after the contact with sulphate of iron(III) solutions at different conditions: type of solvent, temperature, air atmosphere. In special conditions the ultrafine superparamagnetic particles of Fe2O3 have been obtained.

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STOPPED-FLOW SPECTROPHOTOMETRIC STUDIES OF THE KINETICS OF INTERACTION OF DIHYDROXYFUMARIC ACID WITH THE DPPH FREE RADICAL

Author(s):

Secara Natalia


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2010 Volume 5, no.2
Pages: 83-87
Keywords: DPPH; antioxidant activity; stoichiometry; stopped-flow; kinetics; dihydroxyfumaric acid.
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Abstract (JPEG)

DOI:
dx.doi.org/10.19261/cjm.2010.05(2).11

Graphical Abstract:
 The reaction of dihydroxyfumaric acid with the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) was studied using the stopped-flow method, in order to describe the reaction kinetics. Dihydroxyfumaric acid reacts very rapidly with DPPH, the reaction being completed in several minutes. This 2-stoichiometric reaction proceeds in two stages, with reaction orders of 1 and 0.76 with respect to DPPH, and 0.5 and 0.3 with respect to DHF, respectively. The rate constant of the two stages of the reaction were found to be 39.1 (L/mol•s) and 0.0012 (s-1) at 20º C and pH 4.0.

Downloads: 30

AB INITIO STUDY OF CHEMICAL ACTIVATION AND HYDROGENATION OF WHITE PHOSPHORUS IN REACTION WITH RHODIUM TRIHYDRIDE COMPLEX

Author(s):

Iolanta I. Balan, Natalia N. Gorinchoy


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2011 Volume 6, no.2
Pages: 84-90
Keywords: white phosphorus, triphos, rhodium trihydride complex, ab initio calculations.
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Abstract (JPEG)

DOI:
dx.doi.org/10.19261/cjm.2011.06(2).18

Graphical Abstract:
 The four-stage mechanism of reaction of the rhodium trihydride complex [(triphos)RhH3] (triphos=1,1,1-tris(diphenylphosphanylmethyl)ethane) with the white phosphorus molecule resulting in the phosphane and the cyclo-P3 complex [(triphos)M(η3-P3] is analyzed on the basis of ab initio calculations of reactants, products, and intermediate complexes of reaction. It is shown that generation of the transient complex  [(triphos)RhH(η1:η1-P4)] followed by intramolecular hydrogen atom migration from the metal to one of the phosphorus atoms is the energetically favourable process. Calculations also show that P4 molecule is activated by coordination to the above complex: the metal-bonded P-P edge is broken, and the tetrahedron P4 is opened to form the butterfly geometry. This activation is realized mainly due to the one-orbital back donation of 4d-electron density from the atom of Rh to the unoccupied antibonding triple degenerate t1*-MO of P4.

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PHARMACEUTICAL AMORPHOUS ORGANIC MATERIALS CHARACTERIZATION BY USING THE DIFFERENTIAL SCANNING CALORIMETRY AND DYNAMIC MECHANICAL ANALYSIS

Author(s):

Ion Dranca, Igor Povar and Tudor Lupascu


Field: Physical chemistry and chemical physics
Type: Research paper
Issue: 2011 Volume 6, no.2
Pages: 91-95
Keywords: DSC –differential scanning calorimetry; DMA –dynamic mechanical analysis; drugs; excipients; glass transition; α- and β –relaxations; crystallization; kinetics.
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Abstract (JPEG)

DOI:
dx.doi.org/10.19261/cjm.2011.06(2).19

Graphical Abstract:
 This research has been carried out in order to demonstrate the use of differential scanning calorimetry (DSC) in detecting and measuring α- and β-relaxation processes in amorphous pharmaceutical systems. DSC has been employed to study amorphous samples of poly (vinylpyrrolidone) (PVP), indomethacin (InM), and ursodeoxycholic acid (UDA) that are annealed at temperature (Ta) around 0.8 of their glass transition temperature (Tg). Dynamic mechanical analysis (DMA) is used to measure β- relaxation in PVP. Yet, the DSC has been used to study the glassy indomethacin aged at 0 and -10 oC for periods of time up to 109 and 210 days respectively. The results demonstrate the emergence of a small melting peak of the α-polymorph after aging for 69 days at 0°C and for 147 days at -10°C (i.e., ~55°C below the glass transition temperature) that provides evidence of nucleation occurring in the temperature region of the β-relaxation.

Downloads: 21