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Articles 137521 - 137550 of 303972

Full-Text Articles in Physical Sciences and Mathematics

Synthesis, Reaction, And Evaluation Of The Anticancer Activity Of 6,7,8,9-Tetrahydro-5$H$-Cyclohepta[4,5]Selenopheno[2,3-$D$]Pyrimidine Derivatives, Kadi̇r Doğanay, Ünzi̇le Keleştemur, Sevgi̇ Balcioğlu, Burhan Ateş, Ali̇ye Altundaş Jan 2016

Synthesis, Reaction, And Evaluation Of The Anticancer Activity Of 6,7,8,9-Tetrahydro-5$H$-Cyclohepta[4,5]Selenopheno[2,3-$D$]Pyrimidine Derivatives, Kadi̇r Doğanay, Ünzi̇le Keleştemur, Sevgi̇ Balcioğlu, Burhan Ateş, Ali̇ye Altundaş

Turkish Journal of Chemistry

The cyclocondensation of 2-amino-5,6,7,8-tetrahydro-4$H$-cyclohepta[$b$] selenophene-3-carbonitrile (1) with formic acid and formamide gave the selenophenopyrimidine 15 and selenophenopyrimidone 6 derivatives. The reaction of 6 with phosphorus oxychloride produced 4-chloro-6,7,8,9-tetrahydro-5$H$-cyclohepta[4,5] seleno[2,3-$d$]pyrimidine (12), the key compound for our nucleophilic substitution reactions. The hydrazinoselenophenopyrimidine 19 obtained from the reaction of 12 with hydrazine hydrate was converted to its tetrazoloselenophenopyrimidine 21 and triazoloselenophenopyrimidine 26 derivatives. Moreover, the chloropyrimidine derivative was reacted with pyrrolidine and morpholine to afford 4-(1-pyrrolidinyl)-6,7,8,9-tetrahydro-5$H$-cylohepta[4,5]selenopheno[2,3-$d$]pyrimidine (27) and 4-(6,7,8,9-tetrahydro-5$H$-cyclohepta[4,5]selenopheno[2,3-$d$]pirimidin-4-yl)morpholine (28). Anticancer activities of the synthesized compounds were investigated against the MCF-7 breast cancer cell line and the IC$_{50}$ values of these compounds were …

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Synthesis Of Novel Thiazolylpyrazoline Derivatives And Evaluation Of Their Antimicrobial Activities And Cytotoxicities, Aouatef Tabbi, Zafer Asim Kaplancikli, Dahmane Tebbani, Leyla Yurttaş, Zerri̇n Cantürk, Özlem Atli, Merve Baysal, Gülhan Turan Zitouni Jan 2016

Synthesis Of Novel Thiazolylpyrazoline Derivatives And Evaluation Of Their Antimicrobial Activities And Cytotoxicities, Aouatef Tabbi, Zafer Asim Kaplancikli, Dahmane Tebbani, Leyla Yurttaş, Zerri̇n Cantürk, Özlem Atli, Merve Baysal, Gülhan Turan Zitouni

Turkish Journal of Chemistry

Several novel thiazolylpyrazoline derivatives were synthesized by reacting substituted 3,5-diaryl-1-thiocarba\-moyl-2-pyrazolines with phenacylbromides. The structures of the synthesized compounds were confirmed by IR, $^{1}$H NMR, $^{13}$C NMR, and MS spectral data. Their antimicrobial activities against Staphylococcus aureus(ATCC-25923), Enterococcus faecalis} (ATCC-29212), Enterococcus faecalis (ATCC-51922), Listeria monocytogenes (ATCC-1911), Klebsiella pneumoniae (ATCC-700603), Pseudomonas aeruginosa (ATCC-27853), Escherichia coli (ATCC-35218), Escherichia coli (ATCC-25922), Candida albicans (ATCC-90028), Candida glabrata (ATCC-90030), Candida krusei (ATCC-6258), and Candida parapsilosis (ATCC-22019) were investigated. The compounds were also studied for their cytotoxic effects using a MTT assay. Compound 7c showed the highest antimicrobial activity, possessing the same potential as chloramphenicol against K. …

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Isoquinoline-Substituted Triazole And Pyran Derivatives: Synthesis And Computational Studies, Duygu Yeni̇dede, Selçuk Gümüş, Ayşegül Gümüş Jan 2016

Isoquinoline-Substituted Triazole And Pyran Derivatives: Synthesis And Computational Studies, Duygu Yeni̇dede, Selçuk Gümüş, Ayşegül Gümüş

Turkish Journal of Chemistry

The one-pot synthesis of novel 1,4-disubstituted 1,2,3-triazoles from isoquinoline-substituted homopropargyl alcohol backbone is described (42%-88% yields). A ring closing metathesis reaction and an intramolecular Pauson-Khand reaction of enyne system derived from a homopropargyl alcohol backbone to afford the corresponding isoquinoline-substituted dihydropyran and cyclopentenone-pyran, respectively, are also described (54% and 78% yields). Information about the structural, electronic, and physico-chemical properties of the novel compounds, obtained by density functional theory application, is also reported.

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Zr(Iv), Ti(Iv), And V(Iii) Complexes Of Some Benzimidazole, Benzothiazole, And Benzoxazole Ligands: Characterization And Catalyst Efficiency In Ethylene Polymerization, Hamdi Ali Elagab, Helmut G. Alt Jan 2016

Zr(Iv), Ti(Iv), And V(Iii) Complexes Of Some Benzimidazole, Benzothiazole, And Benzoxazole Ligands: Characterization And Catalyst Efficiency In Ethylene Polymerization, Hamdi Ali Elagab, Helmut G. Alt

Turkish Journal of Chemistry

Fifteen complexes of 2, 2-bis- (benzimidazole, benzothiazole, and benzoxazole) compounds with Zr(IV), Ti(IV), and V(III) metal centers were synthesized, characterized, activated with methyalumoxane (MAO), and then tested for catalytic ethylene polymerization. The activities of the various catalysts were found to be functions of the hetero atoms in the ligand frameworks. The activity of the catalyst system \textbf{6}/MAO was found to be 1372 kg PE/mol cat. h. The polyethylene produced with the catalyst system 6/MAO showed high molecular weights (1.84 $\times $ 10$^{6}$ g/mol) and broad molecular weight distributions (PD = 11). This could result from different interactions of the MAO …

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Ag(I) Complexes Of Benzimidazol-2-Ylidene Ligands: A Study Of Catalytic Efficiency Towards Three-Component Coupling Reactions, Rafet Kilinçarslan, Nai̇m Sadiç, Beki̇r Çeti̇nkaya Jan 2016

Ag(I) Complexes Of Benzimidazol-2-Ylidene Ligands: A Study Of Catalytic Efficiency Towards Three-Component Coupling Reactions, Rafet Kilinçarslan, Nai̇m Sadiç, Beki̇r Çeti̇nkaya

Turkish Journal of Chemistry

The $N$-heterocyclic carbene (NHC)--Ag(I) complexes 3a-c were synthesized from benzimidazolium chlorides (2a-c = NHC.HCl), incorporating benzyl derivatives and a 2-methoxyethyl group (a: $^{3}$N = 2,4,6-trimethylbenzyl; b: $^{3}$N = 2,3,5,6-tetramethylbenzyl; c: $^{3}$N = pentamethylbenzyl). The compounds were characterized by spectroscopic and elemental analyses. The synthesized NHC-Ag(I) complexes (3a-c) were tested as catalysts for the catalytic three-component coupling reaction of aldehyde, alkyne, and amine to propargylamines in various solvents. All complexes were active catalysts for catalytic three-component coupling reactions with good yields under neat and mild conditions (after 4 h, yields of up to 94%).

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Newly Synthesized Furanoside-Based Nhc Ligands For The Arylation Of Aldehydes, Serpi̇l Deni̇zalti, Fatma Çeti̇n Telli̇, Seli̇n Yildiran, Azi̇ze Yeşi̇m Salman, Beki̇r Çeti̇nkaya Jan 2016

Newly Synthesized Furanoside-Based Nhc Ligands For The Arylation Of Aldehydes, Serpi̇l Deni̇zalti, Fatma Çeti̇n Telli̇, Seli̇n Yildiran, Azi̇ze Yeşi̇m Salman, Beki̇r Çeti̇nkaya

Turkish Journal of Chemistry

New furanoside-based NHC precursor salts (2) were synthesized using amino alcohols from the chloralose derivatives of glucose (a), galactose (b), and mannose (c). The novel compounds were fully characterized by $^{1}$H NMR, $^{13}$C NMR, and elemental analyses. The catalytic activities of these salts were tested in the arylation of aldehydes as catalysts that were generated in situ from [RhCl(COD)]$_{2}$. In addition, 2a was converted to the rhodium complex 3a in order to compare the results obtained in situ. The newly synthesized compounds were very efficient in terms of yield; nevertheless they did not exhibit a chiral induction.

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Comparison Of Influence Of Nanomaterials On A Glassy Carbon Paste Electrode-Based Bioanode In Biofuel Cells, Sema Aslan, Murat Tutum, Yudum Tepeli̇, Ülkü Anik Jan 2016

Comparison Of Influence Of Nanomaterials On A Glassy Carbon Paste Electrode-Based Bioanode In Biofuel Cells, Sema Aslan, Murat Tutum, Yudum Tepeli̇, Ülkü Anik

Turkish Journal of Chemistry

This paper presents a comparative study of nanomaterial modified glassy carbon paste electrodes (GCPEs) used as bioanodes in enzymatic biofuel cells. The developed bioanode electrodes were obtained by modification of composite GCPEs with glucose oxidase (GOx) and different nanomaterials like manganese(IV) oxide nanoparticle (MnO$_{2}$ np) and aluminum titanate (Al$_{2}$O$_{3}$-TiO$_{2})$ bimetallic nanostructure. These nanostructures were utilized in a GCPE-based enzymatic bioanode construction for the first time. P-benzoquinone mediator was used for the electron transfer between enzyme redox center and bioanode electrode where glucose analyte was used as substrate. A laccase-modified plain GCPE was used as biocathode electrode. Then these electrodes were …

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Experimental And Theoretical Investigation Of The Reaction Between Co$_{2}$ And Carbon Dioxide Binding Organic Liquids, Hi̇lal Tankal, Özge Yüksel Orhan, Erdoğan Alper, Telhat Özdoğan, Hakan Kayi Jan 2016

Experimental And Theoretical Investigation Of The Reaction Between Co$_{2}$ And Carbon Dioxide Binding Organic Liquids, Hi̇lal Tankal, Özge Yüksel Orhan, Erdoğan Alper, Telhat Özdoğan, Hakan Kayi

Turkish Journal of Chemistry

The reaction kinetics of CO$_{2}$ absorption into new carbon dioxide binding organic liquids (CO$_{2}$BOLs) was comprehensively studied to evaluate their potential for CO$_{2}$ removal. A stopped-flow apparatus with conductivity detection was used to determine the CO$_{2}$ absorption kinetics of novel CO$_{2}$BOLs composed of DBN (1,5-diazabicyclo[4.3.0]non-5-ene)/1-propanol and TBD (1,5,7-triazabicyclo[4.4.0]dec-5-ene)/1-butanol. A modified termolecular reaction mechanism for the reaction of CO$_{2}$ with CO$_{2}$BOLs was used to calculate the observed pseudo-first-order rate constant k$_{0}$ (s$^{-1})$ and second-order reaction rate constant k$_{2}$ (m$^{3}$/kmol.s). Experiments were performed by varying organic base (DBN or TBD) weight percentage in alcohol medium for a temperature range of 288-308 K. …

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Adsorption Of Cellulase On Poly(2-Hydroxyethyl Methacrylate) Cryogels Containing Phenylalanine, Murat Yavuz, Oğuz Çakir, Zübeyde Baysal Jan 2016

Adsorption Of Cellulase On Poly(2-Hydroxyethyl Methacrylate) Cryogels Containing Phenylalanine, Murat Yavuz, Oğuz Çakir, Zübeyde Baysal

Turkish Journal of Chemistry

The aim of this study was to prepare a supermacroporous cryogel that can be used for the adsorption of cellulase. The macroporous cryogel of poly(2-hydroxyethyl methacrylate-N-methacryloyl-l-phenylalanine) [p(HEMA-MAPA)] was prepared by copolymerization of 2-hydroxyethyl methacrylate (HEMA) with a functional monomer of N-methacryloyl-l-phenylalanine (MAPA). The cryogel was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and swelling tests. The effects of several parameters such as medium pH, temperature, ionic strength, and flow rate on cellulase adsorption were also investigated. Maximum cellulase adsorption was observed at 25 $^{\circ}$C and pH 4.0. Furthermore, adsorbed cellulase was desorbed from the cryogel by using 1.0 …

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Zr(Iv) Complexes Of Some Heterocyclic Ligands: Synthesis, Characterization, And Ethylene Polymerization Activity, Hamdi Ali Elagab Jan 2016

Zr(Iv) Complexes Of Some Heterocyclic Ligands: Synthesis, Characterization, And Ethylene Polymerization Activity, Hamdi Ali Elagab

Turkish Journal of Chemistry

Thirty-one complexes of bis-(benzimidazole, benzothiazole, and benzoxazole) compounds with Zr(IV) metal centers were synthesized, characterized, activated with methylaluminoxane (MAO), and then tested for catalytic ethylene polymerization. The activities of the various catalysts were found to be functions of the heteroatoms in the ligand frameworks and the structure around the active metal center. The highest activity was obtained with 38/MAO (424 kg E/mol cat. h). The produced polyethylenes showed high molecular weights (41/MAO, 1.9 $\times$ 10$^{6}$ g/mol) and broad molecular weight distributions (38/MAO, M$_{w}$ = 9.64 $\times $ 10$^{5}$ g/mol, PD = 23). This could result from different interactions of the …

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Bismuth(Iii)-Sio$_{2}$ Catalyzed Synthesis Of Polysubstituted Imidazoles With The Participation Of Azaaryl Derivatives Of Aniline In Four-Component Reactions, Zarrin Ghasemi, Ziba Zakeri, Maryam Allahvirdinesbat Jan 2016

Bismuth(Iii)-Sio$_{2}$ Catalyzed Synthesis Of Polysubstituted Imidazoles With The Participation Of Azaaryl Derivatives Of Aniline In Four-Component Reactions, Zarrin Ghasemi, Ziba Zakeri, Maryam Allahvirdinesbat

Turkish Journal of Chemistry

A series of novel polyaromatic derivatives of imidazole were synthesized by Bi(III) nitrate-SiO$_{2}$ catalyzed four-component reactions of benzil, ammonium acetate, aromatic aldehydes, and $N$-heterocyclic derivatives of aniline under solvent-free conditions.

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Mn-Doped Zns Quantum Dots As A Room-Temperature Phosphorescent Probe For Analysis Of Glutamic Acid In Foodstuffs, Hayri̇ye Eda Şatana Kara, Burak Demi̇rhan, Buket Er Demi̇rhan Jan 2016

Mn-Doped Zns Quantum Dots As A Room-Temperature Phosphorescent Probe For Analysis Of Glutamic Acid In Foodstuffs, Hayri̇ye Eda Şatana Kara, Burak Demi̇rhan, Buket Er Demi̇rhan

Turkish Journal of Chemistry

L-cysteine-capped Mn-doped ZnS quantum dots (QDs) were used for the determination of glutamic acid in foodstuffs. This method is based on measurement of the quenching of the phosphorescence intensity of the QDs after interacting with glutamic acid. A linear response was observed from 50 to 500 ng mL$^{-1}$ glutamic acid with a limit of detection of 6.79 ng mL$^{-1}$. Room temperature phosphorescence (RTP) intensity of the QDs was quenched rapidly upon the addition of the quencher and the reaction reached equilibrium within 2 min. The quenching mechanism of phosphorescence of Mn-doped ZnS QDs by glutamic acid is dynamic and the …

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Speciation Of Inorganic Selenium By Solid Phase Extraction Using Nanozirconium Oxide/Boron Oxide Composite Material, Hakan Erdoğan, Özcan Yalçinkaya, Ali̇ Rehber Türker Jan 2016

Speciation Of Inorganic Selenium By Solid Phase Extraction Using Nanozirconium Oxide/Boron Oxide Composite Material, Hakan Erdoğan, Özcan Yalçinkaya, Ali̇ Rehber Türker

Turkish Journal of Chemistry

The speciation and preconcentration of selenium were carried out by solid phase extraction using nanozirconium oxide/boron oxide (ZrO$_{2}$/B$_{2}$O$_{3})$. Electrothermal atomic absorption spectrometry (ETAAS) was used for detection. This preconcentration and/or speciation method depends on the retention of Se(IV) ions selectively as its ammonium pyrrolidine dithiocarbamate (APDC) complex on the sorbent. The effects of pH, flow rate, and volume of sample solution and eluent type were investigated for determining the optimum preconcentration and speciation conditions. The effects of other ions that may interfere with the determination and speciation of selenium were also investigated. Moreover, the analytical performance criteria of the method …

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Degradation Of Bisphenol-A Using A Sonophoto Fenton-Like Hybrid Process Over A Lafeo$_{3}$ Perovskite Catalyst And A Comparison Of Its Activity With That Of A Tio$_{2}$ Photocatalyst, Meral Dükkanci Jan 2016

Degradation Of Bisphenol-A Using A Sonophoto Fenton-Like Hybrid Process Over A Lafeo$_{3}$ Perovskite Catalyst And A Comparison Of Its Activity With That Of A Tio$_{2}$ Photocatalyst, Meral Dükkanci

Turkish Journal of Chemistry

Oxidation of bisphenol-A (BPA) was investigated using a sonophoto Fenton-like hybrid process under visible light irradiation in the presence of iron-containing perovskite LaFeO$_{3}$ catalysts. For this purpose, firstly the perovskite catalyst (LaFeO$_{3})$ was prepared by the sol-gel method and calcined at different temperatures (500, 700, and 800 $^{\circ}$C). The prepared catalysts were characterized using XRD, SEM, FTIR, nitrogen adsorption, UV-vis DRS, and ICP/OES measurements. Among the prepared catalysts the catalyst that was calcined at 500 $^{\circ}$C showed better catalytic activity with respect to degradation and chemical oxygen demand (COD) reduction (of 21.8% and 11.2%, respectively, after 3 h of reaction …

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Production, Purification, And Characterization Of A Thermo-Alkali Stable And Metal-Tolerant Carboxymethylcellulase From Newly Isolated Bacillus Methylotrophicus Y37, Yonca Duman, Yonca Yüzügüllü Karakuş, Arzu Sertel, Fi̇kri̇ye Polat Jan 2016

Production, Purification, And Characterization Of A Thermo-Alkali Stable And Metal-Tolerant Carboxymethylcellulase From Newly Isolated Bacillus Methylotrophicus Y37, Yonca Duman, Yonca Yüzügüllü Karakuş, Arzu Sertel, Fi̇kri̇ye Polat

Turkish Journal of Chemistry

A carboxymethylcellulose (CMC)-degrading bacterium was isolated from soil, identified as Bacillus methylotrophicus according to the physiological properties and analyses of 16S rRNA and a partial sequence of the gyrase A (gyrA) gene, and named as B. methylotrophicus Y37. The CMCase enzyme was purified to homogeneity by 20.4-fold with 21.73% recovery using single-step hydrophobic interaction chromatography and biochemically characterized. CMCase showed a molecular weight of approximately 50 kDa as determined by SDS-PAGE. The activity profile of the CMCase enzyme exhibited optimum activity at 45 $^{\circ}$C and pH 5.0. The activity was highly stable at alkaline pH levels. More than 90% of …

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Synthesis, ($E)$/($Z)$-Isomerization, And Dna Binding, Antibacterial, And Antifungal Activities Of Novel Oximes And $O$-Substituted Oxime Ethers, Hati̇ce Başpinar Küçük, Ayşe Sergüzel Yusufoğlu, Leyla Açik, Betül Aydin, Leyla Arslan Jan 2016

Synthesis, ($E)$/($Z)$-Isomerization, And Dna Binding, Antibacterial, And Antifungal Activities Of Novel Oximes And $O$-Substituted Oxime Ethers, Hati̇ce Başpinar Küçük, Ayşe Sergüzel Yusufoğlu, Leyla Açik, Betül Aydin, Leyla Arslan

Turkish Journal of Chemistry

A series of novel positional oximes (2a-2d), $O$-methyl oxime ethers (3a-3d), and $O$-benzyl oxime ethers (4a-4d) were synthesized in high yields starting from their corresponding methyl 3-, 4-, 6-, and 13-keto tetradecanoates. The synthesized compounds were characterized by $^{1}$H NMR, $^{13}$C NMR, FT-IR, mass, and elemental analyses for their structures and $(E)$/$(Z)$ isomerizations. Their DNA binding abilities were investigated in vitro by agarose gel electrophoresis. The antibacterial and antifungal activities were tested also in vitro against eleven bacterial strains and three fungal strains. The relationship between the structure and the mentioned biological activities was discussed. Compound 2a showed good antibacterial …

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Synthesis Of New Hexahydro-1h-Isoindole-1,3(2h)-Dione Derivatives From 2-Ethyl/Phenyl-3a,4,7,7a-Tetrahydro-1h-Isoindole-1,3-(2h)-Dione, Ayşe Tan, Bi̇rgül Koç, Nurhan Ki̇shali, Ertan Şahi̇n, Yunus Kara Jan 2016

Synthesis Of New Hexahydro-1h-Isoindole-1,3(2h)-Dione Derivatives From 2-Ethyl/Phenyl-3a,4,7,7a-Tetrahydro-1h-Isoindole-1,3-(2h)-Dione, Ayşe Tan, Bi̇rgül Koç, Nurhan Ki̇shali, Ertan Şahi̇n, Yunus Kara

Turkish Journal of Chemistry

A new and appropriate synthesis for hexahydro-1H-isoindole-1,3(2H)-dione derivatives has been developed starting from 3-sulfolene. The epoxidation of 2-ethyl/phenyl-3a,4,7,7a-tetrahydro-1H-isoindole-1,3-(2H)-dione and then the opening of the epoxide with nucleophiles gave hexahydro-1H-isoindole-1,3(2H)-dione derivatives. Amino and triazole derivatives of hexahydro-1H-isoindole-1,3(2H)-dione were synthesized from the formed product by the opening reaction of the epoxide with sodium azide. Hydroxyl analogues were obtained from cis-hydroxylation of 2-ethyl/phenyl-3a,4,7,7a-tetrahydro-1H-isoindole-1,3-(2H)-dione. The hydroxyl groups were converted to acetate.

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An Indirect Model For Sintering Thermodynamics, Yüksel Sarikaya, Müşerref Önal Jan 2016

An Indirect Model For Sintering Thermodynamics, Yüksel Sarikaya, Müşerref Önal

Turkish Journal of Chemistry

A model was proposed and used to calculated the changes in enthalpy $(\Delta H^{o})$, entropy $(\Delta S^{o}),$ and Gibbs energy $(\Delta G^{o})$, as well as equilibrium constant $(K)$ relating to the sintering of alumina compacts. Specific nanopore volume $(V)$ of the compacts was assumed as a thermodynamic variable. A hypothetical equilibrium constant $(K_{h})$ and corresponding Gibbs energy $(\Delta G_{h}^{o})$ were calculated depending on the $V$ value measured after each sintering. The thermodynamic relationships with the SI units were respectively evaluated for the initial-stage $(i)$ sintering between 1000 and 1200 $^{\circ}$C and final-stage $(f)$ sintering between 1200 and 1600 $^{\circ}$C in …

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Speciation Of Trace Metals And Metalloids By Solid Phase Extraction With Spectrometric Detection: A Critical Review, Ali̇ Rehber Türker Jan 2016

Speciation Of Trace Metals And Metalloids By Solid Phase Extraction With Spectrometric Detection: A Critical Review, Ali̇ Rehber Türker

Turkish Journal of Chemistry

Considerable interest is continuing to be shown in the speciation of metals, metalloids, and organometals due to the dependence of their toxicity and mobility on their chemical form. This review focuses on the speciation analysis of metals, metalloids, and organometals by solid phase extraction before spectrometric detection, and all aspects of analytical speciation such as determination of oxidation states and organometallic compounds. Some applications of speciation of metals and metalloids are also presented and discussed in this review. Fractionation, which is used sometimes as speciation, and chromatographic detection are not discussed. This review covers approximately the last four years (2012-March …

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Latest Trends, Green Aspects, And Innovations In Liquid-Phase--Based Microextraction Techniques: A Review, Erkan Yilmaz, Mustafa Soylak Jan 2016

Latest Trends, Green Aspects, And Innovations In Liquid-Phase--Based Microextraction Techniques: A Review, Erkan Yilmaz, Mustafa Soylak

Turkish Journal of Chemistry

Liquid-phase microextraction (LPME) methods including single-drop microextraction (SDME), hollow-fiber LPME (HF-LPME), and dispersive liquid-liquid microextraction (DLLME) have in the very short time since their invention grabbed the attention of scientists. Up to now, LPME methods have shown important innovations for the extraction and preconcentration of both inorganic and organic trace analytes from different matrices. These LPME methods offer unique advantages such as high preconcentration factor for target analytes in a single step, low cost, simplicity, excellent preconcentration capability, sample cleanup and integration of steps, and combined use with almost every analytical measurement technique. We describe the milestones and the combined …

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Chromium Redox Speciation In Food Samples, Krystyna Pyrzynska Jan 2016

Chromium Redox Speciation In Food Samples, Krystyna Pyrzynska

Turkish Journal of Chemistry

Chromium is an element with important biological characteristics, depending on its different species. Cr(III) is considered as essential; however, the Cr(VI) form is classified as carcinogenic.~For this reason, speciation analysis in food samples is a very important question. The proposed data procedures for chromium redox speciation in the literature can be divided into those with the use of online hyphenated techniques and those where appropriate sample pretreatment is necessary. The strategies for nonchromatographic speciation are mainly based on selective liquid--liquid extraction procedures, coprecipitation, selective separation of chromium species using a solid phase extraction column, or complexation reactions. In this paper, …

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Remediation Of Cr(Vi) Via Combined Self-Reduction And Adsorption Bychemically Modified Carbon Sorbents, Mohamed E. Mahmoud, Amr. A. Yakout, Asmaa M. Halbas, Maher M. Osman Jan 2016

Remediation Of Cr(Vi) Via Combined Self-Reduction And Adsorption Bychemically Modified Carbon Sorbents, Mohamed E. Mahmoud, Amr. A. Yakout, Asmaa M. Halbas, Maher M. Osman

Turkish Journal of Chemistry

Hexavalent chromium, Cr(VI), is a highly toxic species, while trivalent chromium, Cr(III), is an essential trace element for humans and other organisms. In the present work, a simple, rapid, and efficient procedure for water treatment of Cr(VI) is described. Active carbon (AC) was chemically treated with HCl and NaOH for the formation of surface modified Acidic-AC and Basic-AC sorbents, respectively. In addition, AC sorbent was treated with HNO$_{3}$ as an oxidizing agent and sodium sulfite as a reducing agent for the formation of Ox-AC and Rd-AC sorbents, respectively. The modified AC sorbents were tested to identify their potential applications in …

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Chromate Surface-Imprinted Silica Gel Sorbent For Speciation Of Cr In Surface Waters, Mariya Mitreva, Ivanka Dakova, Tanya Yordanova, Irina Karadjova Jan 2016

Chromate Surface-Imprinted Silica Gel Sorbent For Speciation Of Cr In Surface Waters, Mariya Mitreva, Ivanka Dakova, Tanya Yordanova, Irina Karadjova

Turkish Journal of Chemistry

This study is focused on the synthesis of chromate anion imprinted sorbent supported on silica gel for nonchromatographic Cr speciation in surface waters. The preparation procedure is based on grafting of 3-methyl-1-trimethoxysilylpropylimidazolium, preliminarily coordinated to CrO$_{4}^{2-}$ as a template ion, onto the surface of silica gel. Sorption and desorption characteristics of surface-imprinted sorbent toward Cr(III) and Cr(VI) were examined by batch solid-phase extraction. An excellent separation of Cr(VI), selectively retained on the sorbent, from Cr(III) remained in the solution, was achieved at pH 2-3 for 20 min. A freshly prepared mixture of ascorbic acid and nitric acid was selected as …

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A Novel Ion-Imprinted Polymeric Sorbent For Separation And Determination Of Chromium(Iii) Species In Wastewater, Barbara Lesniewska, Iwona Jakubowska, Elzbieta Zambrzycka, Beata Godlewska - Zylkiewicz Jan 2016

A Novel Ion-Imprinted Polymeric Sorbent For Separation And Determination Of Chromium(Iii) Species In Wastewater, Barbara Lesniewska, Iwona Jakubowska, Elzbieta Zambrzycka, Beata Godlewska - Zylkiewicz

Turkish Journal of Chemistry

A new chromium(III) ion-imprinted polymer (IIP) was prepared from a Cr(III)-nicotinate complex (template), acrylamide (functional monomer), and ethylene glycol dimethacrylate (cross-linking agent) using 2,2'-azobisisobutyronitrile as the radical initiator. IIP was characterised and used as a selective sorbent for the solid-phase extraction of Cr(III) ions. The conditions for dynamic separation of Cr(III) on IIP were optimised. Cr(III) ions are selectively retained on the sorbent in a pH range from 9 to 10 and can be eluted with 4 mol L$^{-1}$ acetic acid. Cr(III) ions were determined by flame atomic absorption spectrometry (FAAS) with a detection limit of 0.08 $\mu $g mL$^{-1}$. …

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Determination Of Hexavalent Chromium In Aqueous And Alkaline Soil Extracts, Tsvetomil Voyslavov, Stefan Tsakovski, Sonya Ganeva Jan 2016

Determination Of Hexavalent Chromium In Aqueous And Alkaline Soil Extracts, Tsvetomil Voyslavov, Stefan Tsakovski, Sonya Ganeva

Turkish Journal of Chemistry

A fast, simple, and reliable method for determination of hexavalent chromium species in soil aqueous and alkaline extracts has been developed. The procedure is based on the ion-pair extraction of Cr(VI) with methyltrioctylammonium chloride (Aliquat 336) into xylene. The extract is analyzed by flame (FAAS) or electrothermal atomic absorption spectrometry (ETAAS). The method allows the detection of up to 2 mg kg$^{-1}$ Cr(VI) by FAAS and up to 25 $\mu $g kg$^{-1}$ Cr(VI) by ETAAS. The relative standard deviation varied in the range 2%-12% depending on the Cr(VI) levels in the samples. The analysis of certified reference material CRM041-30G Chromium …

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Schiff Base Immobilized Silica Gel Framework As An Efficient Sorbent For Preconcentration Of Pb And Zn Ions In Aqueous Media, Murat Koluman, Feyzullah Tokay, Sema Bağdat Jan 2016

Schiff Base Immobilized Silica Gel Framework As An Efficient Sorbent For Preconcentration Of Pb And Zn Ions In Aqueous Media, Murat Koluman, Feyzullah Tokay, Sema Bağdat

Turkish Journal of Chemistry

A novel preconcentration method for Pb and Zn ions using a column packed with Schiff base modified silica gel is described. The method was based on the sorption of analytes on N,N'-bis(4-methoxysalicylidene)-1,3-propanediamine modified silica gel and elution with HNO$_{3}$ prior to flame atomic absorption analysis. The parameters pH, flow rate, sample volume, eluent volume, and concentration were optimized using a central composite design. The detection limits were 10.0 $\mu $g L$^{-1}$ for Pb and 1.1 $\mu $g L$^{-1}$ for Zn. The suggested procedure was validated with Lake Ontario water as a certified reference material and recovery percentages were 101.8% for …

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Spectrophotometric Determination Of Mercury Using Vortex-Assisted Liquid-Liquid Microextraction, Tatiana Antolova, Serhii Zaruba, Jana Sandrejova, Livia Kocurova, Andriy B. Vishnikin, Yaroslav Bazel, Vasil Andruch, Ioseph S. Balogh Jan 2016

Spectrophotometric Determination Of Mercury Using Vortex-Assisted Liquid-Liquid Microextraction, Tatiana Antolova, Serhii Zaruba, Jana Sandrejova, Livia Kocurova, Andriy B. Vishnikin, Yaroslav Bazel, Vasil Andruch, Ioseph S. Balogh

Turkish Journal of Chemistry

A novel method for the determination of mercury(II) is suggested. The procedure is based on the formation of an ion associate between the bromide complex of Hg(II) and Astrazon Red 6B dye and vortex-assisted liquid-liquid microextraction of the ion associate formed, with subsequent spectrophotometric detection. The variables that affect the procedure, such as pH, the concentration of ligand and dye, the type and volume of extraction solvent, and the rate and time of vortex mixing, were optimized. Under optimum conditions (pH 2.0, 0.01 mol L$^{-1}$ KBr, 2 $\times $ 10$^{-4}$ mol L$^{-1}$ AR6B, 50 $\mu $L of the extraction mixture …

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Preparation Of Fe$_{3}$O$_{4}$ @ Montmorillonite Composite As An Effective Sorbent For The Removal Of Lead And Cadmium From Wastewater Samples, Hande Tinas, Ece Çalişkan, Ni̇l Özbek, Süleyman Akman Jan 2016

Preparation Of Fe$_{3}$O$_{4}$ @ Montmorillonite Composite As An Effective Sorbent For The Removal Of Lead And Cadmium From Wastewater Samples, Hande Tinas, Ece Çalişkan, Ni̇l Özbek, Süleyman Akman

Turkish Journal of Chemistry

A magnetic Fe$_{3}$O$_{4}$ @ montmorillonite composite was prepared and used for the separation of lead and cadmium from aqueous solutions. For this purpose, magnetite (Fe$_{3}$O$_{4})$ was generated by co-precipitation of FeSO$_{4}$ and FeCl$_{3}$ onto montmorillonite. The effects of various experimental parameters such as pH of the solution, amount of sorbent, initial concentration of analytes, and contact time on the sorption efficiencies of lead and cadmium ions were investigated and optimized by applying a batch technique. The concentrations of analytes were determined by high resolution continuum source flame atomic absorption spectrometry. The maximum adsorption occurred at pH 2.0. The adsorption capacity …

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An Application Of Coacervate-Based Extraction For The Separation And Preconcentration Of Cadmium, Lead, And Nickel Ions Prior To Their Determination By Flame Atomic Absorption Spectrometry In Various Water Samples, Anies Awad Satti, İlknur Durukan Temuge, Sema Bektaş, Çi̇ğdem Arpa Şahi̇n Jan 2016

An Application Of Coacervate-Based Extraction For The Separation And Preconcentration Of Cadmium, Lead, And Nickel Ions Prior To Their Determination By Flame Atomic Absorption Spectrometry In Various Water Samples, Anies Awad Satti, İlknur Durukan Temuge, Sema Bektaş, Çi̇ğdem Arpa Şahi̇n

Turkish Journal of Chemistry

Cloud point extraction (CPE), which is the most popular coacervate-based extraction method, was utilized for the separation and preconcentration of trace amounts of cadmium, lead, and nickel. Quinalizarin was used as complexing agent and Triton X-114 was used as surfactant. After extraction, analyte ions were determined by flame atomic absorption spectrometry. The detection limits (3$s)$ of 1.8 $\mu $g L$^{-1}$ for Cd(II), 3.2 $\mu $g L$^{-1}$ for Pb(II), and 2.8 $\mu $g L$^{-1}$ for Ni(II) were obtained using 50 mL of solutions. The relative standard deviation was calculated as 4.3% for 10 $\mu $g L$^{-1}$ Cd(II), 4.9% for 50 $\mu …

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A Simple And Efficient Approach For Preconcentration Of Some Heavy Metals In Cosmetic Products Before Their Determinations By Flame Atomic Absorption Spectrometry, Nai̇l Altunay, Ramazan Gürkan Jan 2016

A Simple And Efficient Approach For Preconcentration Of Some Heavy Metals In Cosmetic Products Before Their Determinations By Flame Atomic Absorption Spectrometry, Nai̇l Altunay, Ramazan Gürkan

Turkish Journal of Chemistry

In the current study, a simple and efficient analytical method for preconcentration and determination of Cd(II), Pb(II), and Sn(II) in some cosmetic samples, using ultrasonic assisted-cloud point extraction and flame atomic absorption spectrometry, was developed. The method is based on the ternary complex formations of Sn(II), Pb(II), and Cd(II), which are available in the form of neutral and/or anionic hydroxo complexes (Sn(OH)$_{3}^{-}$, Pb(OH)$_{3}^{-}$, Cd(OH)$_{2}$, and/or Cd(OH)$_{3}^{-})$, with Victoria Pure Blue BO (VPB$^{+})$ in the presence of cetylpyridinium chloride at pH 8.5, and then extraction of the formed ternary complexes into the micellar phase of polyoxyethylene sorbitan monostearate (Tween 60). Using …

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