Pub Date : 2014-05-06DOI: 10.2478/s11532-014-0562-y
Miroslava Bittová, Eliška Krejzová, Vendula Roblová, P. Kubáň, V. Kuban
AbstractPresented work summarizes the data about polyphenolic profiles in various plant parts (leaves, shoots, berries) of sea buckthorn (Hippophaë rhamnoides L.) during the annual growth cycle. A reversed-phase high performance liquid chromatography method (RP-HPLC) coupled with diode-array detection (DAD) was optimized for determination of catechin, epicatechin, gallic acid, p-coumaric acid, caffeic acid, ferulic acid, rutin (quercetin 3-rutinoside) and quercitrin (quercetin 3-rhamnoside). The content of these polyphenolic compounds was monitored in extracts of sea buckthorn plant samples from April to October. The total antioxidant activity was determined using scavenging of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonate) cation radical (ABTS·+) and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH·). The total content of polyphenols was estimated by conventional spectrophotometric method using Folin-Ciocalteu reagent. The monitoring of temporal changes of selected polyphenolic compounds by RP-HPLC showed that catechin, epicatechin and gallic acid were the most abundant analytes in annual green shoots and leaves, and their content varied significantly during the studied period.
{"title":"Monitoring of HPLC profiles of selected polyphenolic compounds in sea buckthorn (Hippophaë rhamnoides L.) plant parts during annual growth cycle and estimation of their antioxidant potential","authors":"Miroslava Bittová, Eliška Krejzová, Vendula Roblová, P. Kubáň, V. Kuban","doi":"10.2478/s11532-014-0562-y","DOIUrl":"https://doi.org/10.2478/s11532-014-0562-y","url":null,"abstract":"AbstractPresented work summarizes the data about polyphenolic profiles in various plant parts (leaves, shoots, berries) of sea buckthorn (Hippophaë rhamnoides L.) during the annual growth cycle. A reversed-phase high performance liquid chromatography method (RP-HPLC) coupled with diode-array detection (DAD) was optimized for determination of catechin, epicatechin, gallic acid, p-coumaric acid, caffeic acid, ferulic acid, rutin (quercetin 3-rutinoside) and quercitrin (quercetin 3-rhamnoside). The content of these polyphenolic compounds was monitored in extracts of sea buckthorn plant samples from April to October. The total antioxidant activity was determined using scavenging of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonate) cation radical (ABTS·+) and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH·). The total content of polyphenols was estimated by conventional spectrophotometric method using Folin-Ciocalteu reagent. The monitoring of temporal changes of selected polyphenolic compounds by RP-HPLC showed that catechin, epicatechin and gallic acid were the most abundant analytes in annual green shoots and leaves, and their content varied significantly during the studied period.\u0000","PeriodicalId":9888,"journal":{"name":"Central European Journal of Chemistry","volume":"3 1","pages":"1152-1161"},"PeriodicalIF":0.0,"publicationDate":"2014-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85491389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-05-06DOI: 10.2478/s11532-014-0561-z
K. Arefyev, V. I. Grafutin, E. P. Prokopyev, A. Lider, R. Laptev, Yu. S. Bordulev
This article considers the possibility of applying the positron annihilation spectroscopy method for investigating the pore space of rocks from oil-gas and methane-coal deposits. The diagnostics of the structure was performed using the method of spectrometry of angular correlation of annihilation rays (ACAR). Using the samples of porous silicon, the authors have shown the applicability of the ACAR method for determination of the average dimensions of spherical and cylindrical nanosized objects and their concentration
{"title":"Application of positron spectroscopy for investigation of threshold space of oil-gas rocks","authors":"K. Arefyev, V. I. Grafutin, E. P. Prokopyev, A. Lider, R. Laptev, Yu. S. Bordulev","doi":"10.2478/s11532-014-0561-z","DOIUrl":"https://doi.org/10.2478/s11532-014-0561-z","url":null,"abstract":"This article considers the possibility of applying the positron annihilation spectroscopy method for investigating the pore space of rocks from oil-gas and methane-coal deposits. The diagnostics of the structure was performed using the method of spectrometry of angular correlation of annihilation rays (ACAR). Using the samples of porous silicon, the authors have shown the applicability of the ACAR method for determination of the average dimensions of spherical and cylindrical nanosized objects and their concentration","PeriodicalId":9888,"journal":{"name":"Central European Journal of Chemistry","volume":"26 1","pages":"1280-1284"},"PeriodicalIF":0.0,"publicationDate":"2014-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73947348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-05-06DOI: 10.2478/s11532-014-0564-9
V. Bachvarov, Miglena T. Peshova, S. Vitkova, N. Boshkov
AbstractThe presented work reports on the peculiarities of the anodic behavior, corrosion resistance and protective ability of electrodeposited Zn-Ni-P alloys with a different composition in a model corrosion medium of 5% NaCl. Three characteristic coating types have been investigated using experimental methods such as potentiodynamic polarization (PD) technique and polarization resistance (Rp) measurements. In addition, X-ray diffraction (XRD) analysis as well as scanning electron microscopy (SEM) coupled with an Energy-dispersive X-ray (EDAX) device were applied to determine the differences in the chemical composition and surface morphology which appeared as a result of the corrosion treatment. The data obtained are compared to those of electrodeposited pure Zn coatings with identical experimental conditions demonstrating the enhanced protective characteristics of the ternary alloys during the test period in the model medium. The influence of the chemical and phase composition of the alloys on its corrosion resistance and protective ability is also commented and discussed.
{"title":"Corrosion properties of Zn-Ni-P alloys in neutral model medium","authors":"V. Bachvarov, Miglena T. Peshova, S. Vitkova, N. Boshkov","doi":"10.2478/s11532-014-0564-9","DOIUrl":"https://doi.org/10.2478/s11532-014-0564-9","url":null,"abstract":"AbstractThe presented work reports on the peculiarities of the anodic behavior, corrosion resistance and protective ability of electrodeposited Zn-Ni-P alloys with a different composition in a model corrosion medium of 5% NaCl. Three characteristic coating types have been investigated using experimental methods such as potentiodynamic polarization (PD) technique and polarization resistance (Rp) measurements. In addition, X-ray diffraction (XRD) analysis as well as scanning electron microscopy (SEM) coupled with an Energy-dispersive X-ray (EDAX) device were applied to determine the differences in the chemical composition and surface morphology which appeared as a result of the corrosion treatment. The data obtained are compared to those of electrodeposited pure Zn coatings with identical experimental conditions demonstrating the enhanced protective characteristics of the ternary alloys during the test period in the model medium. The influence of the chemical and phase composition of the alloys on its corrosion resistance and protective ability is also commented and discussed.\u0000","PeriodicalId":9888,"journal":{"name":"Central European Journal of Chemistry","volume":"30 1","pages":"1183-1193"},"PeriodicalIF":0.0,"publicationDate":"2014-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88700238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-05-06DOI: 10.2478/s11532-014-0556-9
E. Buruianǎ, M. Murariu, T. Buruiană
AbstractTwo monomers of (D/L), (+/−)-N-methacryloyloxyethyl-N′-2-hydroxybutyl(urea) methacrylate (D/L-MABU) type were prepared and further polymerized through free radical polymerization with optically active monomers containing phenylalanine sequences such as N-acryloyl-(D/L), (−/+)-phenylalanine (A-D/L-Phe). The resulting copolymers, i.e., poly[N-acryloyl-(D/L), (−/+)-phenylalanine-co-(D/L), (+/−)-N-methacryloyloxyethyl-N′-2-hydroxybutyl(urea)], A-D/L-Phe-co-D/L-MABU, were characterized by FT-IR, 1D/2D NMR (1H and 13C), UV-vis, and circular dichroism (CD) spectroscopies, differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). The copolymers obtained with a molar fraction of 0.76: 0.24 / 0.64: 0.36 monomer units had optical rotation values of −25° and +15°, respectively. Upon chemical modification of the phenylalanine-based copolymers with fluorescein-isothiocyanate, new fluorescent copolyacrylates (A-D/L-Phe-co-D/L-MABU-F) were synthesized and further studied for pH measurements in DMF solutions using HCl and NaOH 10−1M. It was found that sterioselectivity of the A-L-Phe-co-L-MABU-F copolymer is higher than of its dextro-form, especially at basic pH.
摘要制备了(D/L)、(+/−)- n -甲基丙烯酰氧乙基- n′-2-羟丁基(尿素)甲基丙烯酸酯(D/L- mabu)两种单体，并与n -丙烯酰-(D/L)、(−/+)-苯丙氨酸(A-D/L- phe)等含苯丙氨酸序列的旋光性单体通过自由基聚合进行了进一步聚合。所得共聚物聚[n -丙烯酰-(D/L)，(−/+)-苯丙氨酸-co-(D/L)，(+/−)- n -甲基丙烯酰氧乙基- n′-2-羟基丁基(尿素)]，A-D/L- ph -co-D/L- mabu，通过FT-IR, 1D/2D NMR (1H和13C)， UV-vis，圆二色性(CD)光谱，差示扫描量热法(DSC)和凝胶渗透色谱(GPC)进行了表征。单体摩尔分数为0.76:0.24 / 0.64:0.36的共聚物旋光度值分别为- 25°和+15°。在用异硫氰酸荧光素对苯丙氨酸基共聚物进行化学改性后，合成了新的荧光共聚物(A-D/ l - pH -co- d /L-MABU-F)，并进一步研究了在DMF溶液中使用HCl和NaOH 10−1M进行pH测量。结果表明，a - l - pH -co- l - mabu -f共聚物的立体选择性高于其右旋形式，特别是在碱性条件下。
{"title":"Synthesis and characterization of poly [N-acryloyl-(D/L), (+/−)-phenylalanine-co-(D/L), (−/+)N-methacryloyloxyethyl-N′-2-hydroxybutyl(urea)] copolymers","authors":"E. Buruianǎ, M. Murariu, T. Buruiană","doi":"10.2478/s11532-014-0556-9","DOIUrl":"https://doi.org/10.2478/s11532-014-0556-9","url":null,"abstract":"AbstractTwo monomers of (D/L), (+/−)-N-methacryloyloxyethyl-N′-2-hydroxybutyl(urea) methacrylate (D/L-MABU) type were prepared and further polymerized through free radical polymerization with optically active monomers containing phenylalanine sequences such as N-acryloyl-(D/L), (−/+)-phenylalanine (A-D/L-Phe). The resulting copolymers, i.e., poly[N-acryloyl-(D/L), (−/+)-phenylalanine-co-(D/L), (+/−)-N-methacryloyloxyethyl-N′-2-hydroxybutyl(urea)], A-D/L-Phe-co-D/L-MABU, were characterized by FT-IR, 1D/2D NMR (1H and 13C), UV-vis, and circular dichroism (CD) spectroscopies, differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). The copolymers obtained with a molar fraction of 0.76: 0.24 / 0.64: 0.36 monomer units had optical rotation values of −25° and +15°, respectively. Upon chemical modification of the phenylalanine-based copolymers with fluorescein-isothiocyanate, new fluorescent copolyacrylates (A-D/L-Phe-co-D/L-MABU-F) were synthesized and further studied for pH measurements in DMF solutions using HCl and NaOH 10−1M. It was found that sterioselectivity of the A-L-Phe-co-L-MABU-F copolymer is higher than of its dextro-form, especially at basic pH.","PeriodicalId":9888,"journal":{"name":"Central European Journal of Chemistry","volume":"64 1","pages":"1056-1066"},"PeriodicalIF":0.0,"publicationDate":"2014-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84041103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-05-01DOI: 10.2478/s11532-014-0516-4
L. Hlavatá, V. Vyskočil, Katarína Beníková, Monika Borbélyová, J. Labuda
AbstractNovel electrochemical DNA-based biosensors with outer-sphere Nafion and chitosan protective membranes were prepared for the evaluation of antioxidant properties of beverages (beer, coffee, and black tea) against prooxidant hydroxyl radicals. A carbon working electrode of a screen-printed three-electrode assembly was modified using a layer-by-layer deposition technique with low molecular weight double-stranded DNA and a Nafion or chitosan film. The membrane-covered DNA biosensors were initially tested with respect to their voltammetric and impedimetric response after the incubation of the beverage and the medium exchange for the solution of the redox indicator [Fe(CN)6]3−/4−. While the Nafion-protected biosensor proved to be suitable for beer and black tea extracts, the chitosan-protected biosensor was successfully used in a coffee extract. Afterwards, the applicability was successfully verified for these biosensors for the detection of a deep degradation of the surface-attached DNA at the incubation in the cleavage agent (hydroxyl radicals generated via Fenton reaction) and for the evaluation of antioxidant properties of coffee and black tea extracts against prooxidant hydroxyl radicals. The investigation of the novel biosensors with a protective membrane represents a significant contribution to the field of electrochemical DNA biosensors utilization.
{"title":"DNA-based biosensors with external Nafion and chitosan membranes for the evaluation of the antioxidant activity of beer, coffee, and tea","authors":"L. Hlavatá, V. Vyskočil, Katarína Beníková, Monika Borbélyová, J. Labuda","doi":"10.2478/s11532-014-0516-4","DOIUrl":"https://doi.org/10.2478/s11532-014-0516-4","url":null,"abstract":"AbstractNovel electrochemical DNA-based biosensors with outer-sphere Nafion and chitosan protective membranes were prepared for the evaluation of antioxidant properties of beverages (beer, coffee, and black tea) against prooxidant hydroxyl radicals. A carbon working electrode of a screen-printed three-electrode assembly was modified using a layer-by-layer deposition technique with low molecular weight double-stranded DNA and a Nafion or chitosan film. The membrane-covered DNA biosensors were initially tested with respect to their voltammetric and impedimetric response after the incubation of the beverage and the medium exchange for the solution of the redox indicator [Fe(CN)6]3−/4−. While the Nafion-protected biosensor proved to be suitable for beer and black tea extracts, the chitosan-protected biosensor was successfully used in a coffee extract. Afterwards, the applicability was successfully verified for these biosensors for the detection of a deep degradation of the surface-attached DNA at the incubation in the cleavage agent (hydroxyl radicals generated via Fenton reaction) and for the evaluation of antioxidant properties of coffee and black tea extracts against prooxidant hydroxyl radicals. The investigation of the novel biosensors with a protective membrane represents a significant contribution to the field of electrochemical DNA biosensors utilization.\u0000","PeriodicalId":9888,"journal":{"name":"Central European Journal of Chemistry","volume":"8 1","pages":"604-611"},"PeriodicalIF":0.0,"publicationDate":"2014-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84773643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-05-01DOI: 10.2478/s11532-014-0545-z
M. Albu, Z. Vuluga, D. Panaitescu, D. Vuluga, A. Casarica, M. Ghiurea
The aim of this paper was to prepare composites of bacterial cellulose (BC) and collagen to evaluate both the effect of collagen on the morphological, mechanical and thermal properties of BC and the effect of BC on the thermal stability of collagen for designing composites with increased potential biomedical applications. Two series of composites were prepared, the first series by immersing BC pellicle in solutions of collagen obtained in three forms, collagen gel (CG), collagen solution (CS) and hydrolysed collagen (HC), followed by freeze drying; and the second series of composites by mixing BC powder in solutions of collagen (CG, CS and HC), also followed by freeze drying. The properties of obtained composites were evaluated by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), mechanical tests, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results revealed that BC acts as a thermal stabilizer for CS matrix, while with CG matrix it interacts synergistically leading to composites with improved properties. On the other hand, the BC sheet impregnated with collagen has a significantly improved thermal stability. Collagen (as HC, CS or CG) has also a positive influence on the mechanical properties of lyophilized BC sheet. A four times increase of modulus was observed in BC/HC and BC/CG composites. and an increase of 60 times for BC/CS. The spectacular increase of elastic modulus and tensile strength in the case of BC/CS composite was explained by the easier penetration of collagen solution in the BC network and impregnation of BC fibrils as revealed by SEM and AFM analyzes.
{"title":"Morphology and thermal stability of bacterial cellulose/collagen composites","authors":"M. Albu, Z. Vuluga, D. Panaitescu, D. Vuluga, A. Casarica, M. Ghiurea","doi":"10.2478/s11532-014-0545-z","DOIUrl":"https://doi.org/10.2478/s11532-014-0545-z","url":null,"abstract":"The aim of this paper was to prepare composites of bacterial cellulose (BC) and collagen to evaluate both the effect of collagen on the morphological, mechanical and thermal properties of BC and the effect of BC on the thermal stability of collagen for designing composites with increased potential biomedical applications. Two series of composites were prepared, the first series by immersing BC pellicle in solutions of collagen obtained in three forms, collagen gel (CG), collagen solution (CS) and hydrolysed collagen (HC), followed by freeze drying; and the second series of composites by mixing BC powder in solutions of collagen (CG, CS and HC), also followed by freeze drying. The properties of obtained composites were evaluated by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), mechanical tests, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results revealed that BC acts as a thermal stabilizer for CS matrix, while with CG matrix it interacts synergistically leading to composites with improved properties. On the other hand, the BC sheet impregnated with collagen has a significantly improved thermal stability. Collagen (as HC, CS or CG) has also a positive influence on the mechanical properties of lyophilized BC sheet. A four times increase of modulus was observed in BC/HC and BC/CG composites. and an increase of 60 times for BC/CS. The spectacular increase of elastic modulus and tensile strength in the case of BC/CS composite was explained by the easier penetration of collagen solution in the BC network and impregnation of BC fibrils as revealed by SEM and AFM analyzes.","PeriodicalId":9888,"journal":{"name":"Central European Journal of Chemistry","volume":"22 1","pages":"968-975"},"PeriodicalIF":0.0,"publicationDate":"2014-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82100952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-04-30DOI: 10.2478/S11532-014-0559-6
Catinca Secuianu, J. Jaubert, H. Iovu
Abstract
摘要
{"title":"Editor’s preface for the special issue “Romanian International Conference on Chemistry and Chemical Engineering”","authors":"Catinca Secuianu, J. Jaubert, H. Iovu","doi":"10.2478/S11532-014-0559-6","DOIUrl":"https://doi.org/10.2478/S11532-014-0559-6","url":null,"abstract":"Abstract","PeriodicalId":9888,"journal":{"name":"Central European Journal of Chemistry","volume":"117 1","pages":"747-748"},"PeriodicalIF":0.0,"publicationDate":"2014-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79371365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-04-29DOI: 10.2478/s11532-014-0552-0
M. Shamsipur, M. Roushani, S. M. Pourmortazavi, N. Shahabadi
AbstractElectrocatalytic oxidation of sulfide ion on a glassy carbon electrode (GCE) modified with multiwall carbon nanotubes (MWCNTs) and a copper (II) complex was investigated. The Cu(II) complex was used due to the reversibility of the Cu(II)/Cu(III) redox couple. The MWCNTs are evaluated as a transducer, stabilizer and immobilization matrix for the construction of amperometric sensor based on Cu(II) complex adsorbed on MWCNTs immobilized on the surface of GCE. The modified GCE was applied to the selective amperometric detection of sulfide at a potential of 0.47 V (vs. Ag/AgCl) at pH 8.0. The calibration graph was linear in the concentration range of 5 µM–400 µM; while the limit of detection was 1.2 µM, the sensitivity was 34 nA µM−1. The interference effects of SO32−, SO42−, S2O32−, S4O62−, Cysteine, and Cystein were negligible at the concentration ratios more than 40 times. The modified electrode is more stable with time and more easily restorable than unmodified electrode surface. Also, modified electrode permits detection of sulfide ion by its oxidation at lower anodic potentials.
摘要研究了多壁碳纳米管(MWCNTs)和铜(II)配合物修饰的玻碳电极(GCE)上硫化物离子的电催化氧化。由于Cu(II)/Cu(III)氧化还原对的可逆性，采用了Cu(II)配合物。MWCNTs作为传感器、稳定剂和固定化基质，可用于构建基于Cu(II)配合物的GCE表面固定化MWCNTs的电流传感器。将改进的GCE应用于pH 8.0条件下，在0.47 V (vs. Ag/AgCl)电位下的选择性安培检测硫化物。在5µM - 400µM浓度范围内，校正曲线呈线性关系;检测限为1.2µM，灵敏度为34 nAµM−1。在浓度比大于40倍时，SO32−、SO42−、S2O32−、S4O62−、半胱氨酸和半胱氨酸的干扰作用可以忽略不计。修饰后的电极表面比未修饰的电极表面更稳定，更容易恢复。此外，改进的电极允许在较低的阳极电位下通过其氧化来检测硫化物离子。
{"title":"Amperometric determination of sulfide ion by glassy carbon electrode modified with multiwall carbon nanotubes and copper (II) phenanthroline complex","authors":"M. Shamsipur, M. Roushani, S. M. Pourmortazavi, N. Shahabadi","doi":"10.2478/s11532-014-0552-0","DOIUrl":"https://doi.org/10.2478/s11532-014-0552-0","url":null,"abstract":"AbstractElectrocatalytic oxidation of sulfide ion on a glassy carbon electrode (GCE) modified with multiwall carbon nanotubes (MWCNTs) and a copper (II) complex was investigated. The Cu(II) complex was used due to the reversibility of the Cu(II)/Cu(III) redox couple. The MWCNTs are evaluated as a transducer, stabilizer and immobilization matrix for the construction of amperometric sensor based on Cu(II) complex adsorbed on MWCNTs immobilized on the surface of GCE. The modified GCE was applied to the selective amperometric detection of sulfide at a potential of 0.47 V (vs. Ag/AgCl) at pH 8.0. The calibration graph was linear in the concentration range of 5 µM–400 µM; while the limit of detection was 1.2 µM, the sensitivity was 34 nA µM−1. The interference effects of SO32−, SO42−, S2O32−, S4O62−, Cysteine, and Cystein were negligible at the concentration ratios more than 40 times. The modified electrode is more stable with time and more easily restorable than unmodified electrode surface. Also, modified electrode permits detection of sulfide ion by its oxidation at lower anodic potentials.\u0000","PeriodicalId":9888,"journal":{"name":"Central European Journal of Chemistry","volume":"2 1","pages":"1091-1099"},"PeriodicalIF":0.0,"publicationDate":"2014-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89248202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-04-29DOI: 10.2478/s11532-014-0549-8
E. Tolis, E. Gkanas, E. Pavlidou, Athina Skemperi, J. Pey, N. Pérez, J. Bartzis
AbstractScientists are interested in knowing more about the control of sources which contribute to environmental pollution. Air pollution has two main sources: anthropogenic and natural sources. The natural contributions to environmental pollution can be assessed, but cannot be totally controlled. while the emissions from the anthropogenic sources can be controlled. These air pollutants can be dispersed and transferred by winds in the atmosphere. The focus area of this study is the Mediterranean basin. The most important winds in this area are the land and sea breezes. Scanning Electron Microscopy (SEM) was applied to characterize the morphology of the PM10 samples in order to identify possible emission sources for the occuring pollution. Energy Dispersive X-ray Spectroscopy (EDS) was performed for the elemental analysis and chemical characterization of the PM10 samples. The analysis showed that the PM10 samples can be divided into three different groups: the samples containing mineral phases, the compounds from combustion processes and the particles emitted from high-temperature processes.
{"title":"Microstuctural analysis and determination of PM10 emission sources in an industrial Mediterranean city","authors":"E. Tolis, E. Gkanas, E. Pavlidou, Athina Skemperi, J. Pey, N. Pérez, J. Bartzis","doi":"10.2478/s11532-014-0549-8","DOIUrl":"https://doi.org/10.2478/s11532-014-0549-8","url":null,"abstract":"AbstractScientists are interested in knowing more about the control of sources which contribute to environmental pollution. Air pollution has two main sources: anthropogenic and natural sources. The natural contributions to environmental pollution can be assessed, but cannot be totally controlled. while the emissions from the anthropogenic sources can be controlled. These air pollutants can be dispersed and transferred by winds in the atmosphere. The focus area of this study is the Mediterranean basin. The most important winds in this area are the land and sea breezes. Scanning Electron Microscopy (SEM) was applied to characterize the morphology of the PM10 samples in order to identify possible emission sources for the occuring pollution. Energy Dispersive X-ray Spectroscopy (EDS) was performed for the elemental analysis and chemical characterization of the PM10 samples. The analysis showed that the PM10 samples can be divided into three different groups: the samples containing mineral phases, the compounds from combustion processes and the particles emitted from high-temperature processes.\u0000","PeriodicalId":9888,"journal":{"name":"Central European Journal of Chemistry","volume":"251 1","pages":"1081-1090"},"PeriodicalIF":0.0,"publicationDate":"2014-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76886828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-04-16DOI: 10.2478/s11532-014-0555-x
R. Razo‐Hernández, K. Pineda‐Urbina, M. A. Velazco‐Medel, Manuel Villanueva-García, M. Sumaya‐Martínez, F. Martínez-Martínez, Z. Gómez‐Sandoval
AbstractA Quantitative Structure-Activity Relationship (QSAR) of coumarins by genetic algorithms employing physicochemical, topological, lipophilic and electronic descriptors was performed. We have used experimental antioxidant activities of specific coumarin derivatives against the DPPH· radical molecule. Molecular descriptors such as Randic Path/Walk, hydrophilic factor and chemical hardness were selected to propose a mathematical model. We obtained a linear correlation with R2 = 96.65 and QLOO2 = 93.14 values. The evaluation of the predictive ability of the model was performed by applying the QASYM2, $hat r^2 $ and Δrm2 methods. Fukui functions were calculated here for coumarin derivatives in order to delve into the mechanics by which they work as primary antioxidants. We also investigated xanthine oxidase inhibition with these coumarins by molecular docking. Our results show that hydrophobic, electrostatic and hydrogen bond interactions are crucial in the inhibition of xanthine oxidase by coumarins.
{"title":"QSAR study of the DPPH· radical scavenging activity of coumarin derivatives and xanthine oxidase inhibition by molecular docking","authors":"R. Razo‐Hernández, K. Pineda‐Urbina, M. A. Velazco‐Medel, Manuel Villanueva-García, M. Sumaya‐Martínez, F. Martínez-Martínez, Z. Gómez‐Sandoval","doi":"10.2478/s11532-014-0555-x","DOIUrl":"https://doi.org/10.2478/s11532-014-0555-x","url":null,"abstract":"AbstractA Quantitative Structure-Activity Relationship (QSAR) of coumarins by genetic algorithms employing physicochemical, topological, lipophilic and electronic descriptors was performed. We have used experimental antioxidant activities of specific coumarin derivatives against the DPPH· radical molecule. Molecular descriptors such as Randic Path/Walk, hydrophilic factor and chemical hardness were selected to propose a mathematical model. We obtained a linear correlation with R2 = 96.65 and QLOO2 = 93.14 values. The evaluation of the predictive ability of the model was performed by applying the QASYM2, $hat r^2 $ and Δrm2 methods. Fukui functions were calculated here for coumarin derivatives in order to delve into the mechanics by which they work as primary antioxidants. We also investigated xanthine oxidase inhibition with these coumarins by molecular docking. Our results show that hydrophobic, electrostatic and hydrogen bond interactions are crucial in the inhibition of xanthine oxidase by coumarins.\u0000","PeriodicalId":9888,"journal":{"name":"Central European Journal of Chemistry","volume":"20 1","pages":"1067-1080"},"PeriodicalIF":0.0,"publicationDate":"2014-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85916645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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