South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie最新文献_第9页

Understanding How Chemistry Teachers Transform Stoichiometry Concepts at Secondary Level in Lesotho 了解莱索托中学化学教师如何转变化学计量概念

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2019-01-01 DOI: 10.17159/0379-4350/2019/V72A9

Mamohato Makhechane, Makomosela Qhobela

引用次数: 11

Experimental, Statistical Modelling and Molecular Dynamics Simulation Concept of Sapium ellipticum Leaf Extract as Corrosion Inhibitor for Carbon Steel in Acid Environment 椭圆皂叶提取物在酸性环境中作为碳钢缓蚀剂的实验、统计建模和分子动力学模拟概念

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2019-01-01 DOI: 10.17159/0379-4350/2019/v72a22

C. S. Okafor, V. Anadebe, O. Onukwuli

引用次数: 16

Calcination of Precipitated Calcium Carbonate with Surfactant-assisted Agglomeration -A Non-isothermal Topochemical Approach 表面活性剂辅助团聚煅烧沉淀碳酸钙——非等温拓扑化学方法

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2019-01-01 DOI: 10.17159/0379-4350/2019/v72a15

D. Dasgupta, T. Wiltowski

{"title":"Calcination of Precipitated Calcium Carbonate with Surfactant-assisted Agglomeration -A Non-isothermal Topochemical Approach","authors":"D. Dasgupta, T. Wiltowski","doi":"10.17159/0379-4350/2019/v72a15","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/v72a15","url":null,"abstract":"It has been shown that precipitated calcium carbonate prepared by surfactant-assisted agglomeration (PCC-SAA) provided higher capacity for the carbon dioxide capture during calcination carbonation cycling as compared to commercially available calcium carbonate. It was also shown previously that the capacity was maintained over multiple cycles while commercially available calcium carbonate significantly lost its capacity. In order to understand the differences in the calcination behaviour of the PCC-SAA sample as compared to the commercially available laboratory-grade calcium carbonate (AC) sample, a nonisothermal topochemical approach was adopted to delineate the various controlling mechanisms for calcination of CaCO3. Activation energies were calculated using iso-conversional methods such as Friedman’s method, the KSA method, and the FWO method. In addition, the mechanism was identified at different heating rates by applying the Malek’s method and evaluated in some cases using the JMA kinetics. Finally, four mechanisms were used to calculate the pre-exponential (frequency factor). Some key differences such as the initiation temperature, and mechanisms were found between the two samples. Generally, it was found that the differences in the two samples were primarily due to the structural causes. It was observed that the initiation temperature for CaCO3 decomposition, activation energies and mechanisms were a function of the heating rates. D2 or D4 was identified as the controlling mechanisms at lower temperatures for the PCC-SAA sample in contrast to JMA (n > 1) kinetics for the higher heating rates. For the AC sample, 3D diffusion process appears to control the calcination of the AC sample.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67463049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Concentration of Total Mercury in Convenience Fish Products and Cooked Fish 便利鱼制品及熟鱼中总汞的浓度

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2019-01-01 DOI: 10.17159/0379-4350/2019/v72a19

N. Panichev, S. Panicheva

引用次数: 0

Structural and Morphological Behaviour and Study of the Colorimetric and Reflective Properties of Commercial Inorganic Pigments 商用无机颜料的结构形态行为及比色和反射性能研究

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2019-01-01 DOI: 10.17159/0379-4350/2019/v72a28

Ketlyn Wolfart Borth, Rayane Ferreira, D. Galante, F. Anaissi, Marcia Gabriela Pianaro Valenga

{"title":"Structural and Morphological Behaviour and Study of the Colorimetric and Reflective Properties of Commercial Inorganic Pigments","authors":"Ketlyn Wolfart Borth, Rayane Ferreira, D. Galante, F. Anaissi, Marcia Gabriela Pianaro Valenga","doi":"10.17159/0379-4350/2019/v72a28","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/v72a28","url":null,"abstract":"Characterization of colourful materials must include reflective, spectroscopic and colorimetric properties. Therefore, powder commercial pigments (Xadrez) were investigated to identify their structure, morphology, composition and real colour, in order to use them as patterns to new materials. Results from X-ray diffraction, X-ray fluorescence spectroscopy and electronic spectroscopy indicated the compounds that give colour to the pigments brown, red, yellow and black as, generally, iron oxides, in the phases hematite (á-Fe2O3), goethite (á-FeOOH) and magnesium ferrite (MgFe2O4), in different proportions. Meanwhile, blue and green pigments contained copper phthalocyanine and other compounds responsible for their colour. Commercial pigments presented different degrees of solar reflectance: the highest value was 44.7 % to white pigment and the lowest 2.2 % to black pigment. Colorimetric data made it possible to calculate the real colour of the pigments, using the free software of ColorMine library, and, then, to assess the colour of new synthetic pigments.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67463116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Mononuclear Schiff Base Complexes Derived from 5-Azophenylsalicylaldehyde with Co(II), Ni(II) Ions: Synthesis, Characterization, Electrochemical Study and Antibacterial Properties 含Co(II)、Ni(II)离子的5-偶氮苯基水杨醛单核席夫碱配合物的合成、表征、电化学研究及抗菌性能

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2019-01-01 DOI: 10.17159/0379-4350/2019/V72A13

L. Kafi‐Ahmadi, A. P. Marjani

{"title":"Mononuclear Schiff Base Complexes Derived from 5-Azophenylsalicylaldehyde with Co(II), Ni(II) Ions: Synthesis, Characterization, Electrochemical Study and Antibacterial Properties","authors":"L. Kafi‐Ahmadi, A. P. Marjani","doi":"10.17159/0379-4350/2019/V72A13","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/V72A13","url":null,"abstract":"In the present research, 1,2-di[N-2-phenylthio-5-azophenylsalicylidene]ethane (H2L ), 1,3-di[N-2-phenylthio-5-azophenylsalicylidene]propane(H2L ) and 1,4-di[N-2-phenylthio-5-azophenylsalicylidene]butane (H2L ) were synthesized. ML, ML and ML complexes were prepared through the reaction of H2L , H2L 2 and H2L 3 with Ni(II) and Co(II) acetate salts. The prepared ligands and their complexes were characterized with FT-IR, H-NMR, elemental analysis, conductivity and magnetic measurements, ESI-mass, UV-Vis spectroscopy and cyclic voltammetry. The complexes had monomeric structure according to the mass spectral data. All of the complexes had a six-coordinated octahedral geometry. The electrochemical behavior of the ligands, Ni(II) and Co(II) complexes was investigated by CV in DMF under argon atmosphere. The results show that the coordination of Ni(II) causes the ligands to be deactivated. The voltammogram of Co(II) complexes shows that the reduction of CoL is harder than CoL and CoL is inactive. Their antibacterial activity was investigated and the complexes exhibited better antibacterial activity than the free ligands against selective bacteria.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67463011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Control of Electric Dipole Moment using Deformation induced by Functionalization of (5, 0) Zigzag Carbon Nanotubes as Gigahertz Oscillators 利用(5,0)之字形碳纳米管作为千兆赫振荡器的功能化变形控制电偶极矩

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2019-01-01 DOI: 10.17159/0379-4350/2019/v72a29

S. Rastani, H. Mostaanzadeh

{"title":"Control of Electric Dipole Moment using Deformation induced by Functionalization of (5, 0) Zigzag Carbon Nanotubes as Gigahertz Oscillators","authors":"S. Rastani, H. Mostaanzadeh","doi":"10.17159/0379-4350/2019/v72a29","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/v72a29","url":null,"abstract":"Electric dipole moment (EDM) required for the relative motion of carbon nanotube (CNT) walls in nanoelectromechanical systems (NEMS) such as actuators and oscillators is studied by functionalization. Pristine (5, 0) zigzag carbon nanotube with little inherent electric dipole moment (ì) were deformed by adding three –OH functional groups to its end rims. The properties of eight yielded isomers are studied. The Gibbs free energy calculations demonstrate that the eight structures are more stable than pristine CNT. The induced deformation resulted in charge imbalances which developed large electric dipole moments for each case. The values of dipole moments produced for all cases are calculated. The bandgap energy, conductivity, density of state (DOS) and IR spectra of these structures are also computed and analyzed. The study revealed that the location of the –OH positioning (site selectivity) which gives rise to different degrees of deformation has a significant impact on all of the above parameters, especially the magnitude and direction of the electric dipole moment. The functionalization produced large ì of about 6.9 D for 60 carbon atoms nanotube which is higher than in the previous study. Applying an external electric field to the isomers causes the CNTs with large dipole moments to either get attracted or repelled and hence physical movement or oscillation of the nanotube occurs. The frequency of this oscillation is in gigahertz scale.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67463130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Molecularly Imprinted Polymer Solid Phase Extraction followed by High-Performance Liquid Chromatography as an Efficient and Sensitive Technique for Determination of Meropenem in Human Plasma and Urine 分子印迹聚合物固相萃取-高效液相色谱法测定人血浆和尿液中的美罗培南

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2019-01-01 DOI: 10.17159/0379-4350/2019/V72A5

Hamoon Sami Amlashi, Ameneh Porgham Daryasari, M. Soleimani

引用次数: 3

The South African Journal of Chemistry 1918-2018: A Celebration 南非化学杂志1918-2018:庆祝活动

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2019-01-01 DOI: 10.17159/0379-4350/2019/v72a26

T. A. Ford, H. Kruger, P. Loyson

引用次数: 0

Molecular Structure, FT-IR, NMR (13C/1H), UV-Vis Spectroscopy and DFT Calculations on (2Z, 5Z)-3-N(4-Methoxy phenyl)-2-N'(4-methoxy phenyl imino)-5-((E)-3-(2-nitrophenyl)allylidene) thiazolidin-4-one (2Z, 5Z)-3- n(4-甲氧基苯基)-2- n '(4-甲氧基苯基亚胺)-5-((E)-3-(2-硝基苯基)烯丙基)噻唑烷-4-one的分子结构、FT-IR、NMR (13C/1H)、UV-Vis光谱和DFT计算

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2019-01-01 DOI: 10.17159/0379-4350/2019/v72a23

Rachida Rahmani, Ahmed Djafri, A. Chouaih, A. Djafri, F. Hamzaoui, A. Krallafa

{"title":"Molecular Structure, FT-IR, NMR (13C/1H), UV-Vis Spectroscopy and DFT Calculations on (2Z, 5Z)-3-N(4-Methoxy phenyl)-2-N'(4-methoxy phenyl imino)-5-((E)-3-(2-nitrophenyl)allylidene) thiazolidin-4-one","authors":"Rachida Rahmani, Ahmed Djafri, A. Chouaih, A. Djafri, F. Hamzaoui, A. Krallafa","doi":"10.17159/0379-4350/2019/v72a23","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/v72a23","url":null,"abstract":"In this study, some molecular properties of (2Z, 5Z)-3-N(4-methoxy phenyl)-2-N’(4-methoxy phenyl imino)-5-((E)-3-(2-nitrophenyl) allylidene) thiazolidin-4-one (MNTZ) are evaluated using a combination of spectroscopic characterization (FT-IR, H and C NMR chemical shifts) and theoretical calculations. Molecular geometry, vibrational wavenumbers, gauge-independent atomic orbital (GIAO), H and C chemical shift values and NBO analysis are investigated using B3LYP and PBE functionals with the 6-31G(d,p) basis set in the ground state. The calculated geometrical parameters and vibrational spectra are compared to available experimental data and each vibrational frequency is assigned on the basis of potential energy distribution (PED). The electronic transitions are calculated using time-dependent density functional theory (TDDFT). The energy band gap between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies are obtained by computing the frontier molecular orbitals using the B3LYP/6-31G(d,p) and PBE/6-31G(d,p) levels along with the global reactivity descriptors. Mulliken atomic charges and molecular electrostatic potential (MEP) are simulated using both functionals to find more reactive sites for electrophilic and nucleophilic attack. Finally, the thermodynamic functions (heat capacity, entropy, and enthalpy) from spectroscopic data are obtained and discussed in the range of 100–1000 K.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67463477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 9