South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie最新文献_第10页

An Investigation into the Corrosion Rates of Inconel 600™ in Different Corrosive Solutions Inconel 600™在不同腐蚀溶液中的腐蚀速率研究

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/v72a18

B. Davoren, E. Ferg, N. Rust

{"title":"An Investigation into the Corrosion Rates of Inconel 600™ in Different Corrosive Solutions","authors":"B. Davoren, E. Ferg, N. Rust","doi":"10.17159/0379-4350/2019/v72a18","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/v72a18","url":null,"abstract":"Inconel 600TM, an austenitic high nickel alloy, has relatively low corrosion properties and is used extensively for aerospace and nuclear engineering applications. Other applications include exposure of the material to caustic and acidic environments and possible use in prosthetic implants. Electrochemical techniques, which include potentiodynamic polarization and polarization resistance, provide a means to rapidly determine the corrosion rates and the suitability of the alloy in a specific corrosive environment. The results from these two techniques were used to determine the corrosion rates as well as other thermodynamic properties for the alloy exposed to various strong and weak acids, salt and Ringer’s solution. The results showed slight differences in the corrosion rates determined by the two electrochemical techniques, with those from the polarization resistance technique being on average larger. The corrosion activation energies determined for the alloy in different solutions were indicative of the corrosion rates with some anomalies in values for results observed in the 10 % acetic acid solution. The microstructural composition of the alloy was also investigated by SEM-EDS and showed peculiar inclusions that can contribute to an acceleration of the corrosion","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67462887","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

Novel Coumarin Derivatives: Synthesis, Characterization and Antimicrobial Activity 新型香豆素衍生物:合成、表征及抗菌活性

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/v72a32

C. G. Naik, G. Malik, H. Parekh

引用次数: 9

Caffeine and Ciprofloxacin Adsorption from Water onto Clinoptilolite: Linear Isotherms, Kinetics, Thermodynamic and Mechanistic Studies 斜沸石吸附水中咖啡因和环丙沙星:线性等温线、动力学、热力学和机理研究

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/v72a17

E. Ngeno, Victor O. Shikuku, Francis Orata, Lilechi D. Baraza, S. Kimosop

{"title":"Caffeine and Ciprofloxacin Adsorption from Water onto Clinoptilolite: Linear Isotherms, Kinetics, Thermodynamic and Mechanistic Studies","authors":"E. Ngeno, Victor O. Shikuku, Francis Orata, Lilechi D. Baraza, S. Kimosop","doi":"10.17159/0379-4350/2019/v72a17","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/v72a17","url":null,"abstract":"In this study, clinoptilolite was used to sequester ciprofloxacin (CIP) and caffeine (CAF), two emergent contaminants, from aqueous solution using batch equilibration method and the effects of contact time, pH, initial contaminant concentration, temperature and adsorbent dosage investigated and herein reported. The adsorption kinetics was described by the pseudo-second-order model (PSO) and pore diffusion was not the sole operative rate-controlling step as depicted by the intraparticle diffusion model. The equilibrium data were modelled using three linear forms of Langmuir equation and Freundlich model and was best fitted by the Lineweaver-Burk linearization of Langmuir equation (type-1). Linearization is shown to induce errors that may lead to discrepancies in parameter values estimation. The derived thermodynamic functions revealed the adsorption processes are exothermic, spontaneous and physical in nature. The adsorption mechanism of CIP is strongly controlled by electrostatic interactions while CAF adsorption is weakly affected by changes in pH. The findings demonstrate that clinoptilolite in its unmodified form is a potential low-cost and eco-friendly adsorbent for removal of pharmaceutically active ingredients from water.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67462764","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: 15

Co-encapsulation of Rifampicin and Isoniazid in Crude Soybean Lecithin Liposomes 利福平与异烟肼在粗大豆卵磷脂脂质体中的共包封

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/V72A11

C. I. Nkanga, X. Noundou, R. B. Walker, R. Krause

{"title":"Co-encapsulation of Rifampicin and Isoniazid in Crude Soybean Lecithin Liposomes","authors":"C. I. Nkanga, X. Noundou, R. B. Walker, R. Krause","doi":"10.17159/0379-4350/2019/V72A11","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/V72A11","url":null,"abstract":"Despite the well-known anti-mycobacterial actions of isoniazid (INH) and rifampicin (RIF), the clinical success of tuberculosis (TB) therapy requires prolonged administration of multiple drugs in high doses, which often result in frequent adverse effects and low patient adherence. Although liposomes are promising candidates for controlled delivery of anti-TB drug, the high cost of synthetic and highly purified natural lipids currently used in liposomal technology might preclude the universal application of therapeutic liposomes. This work aimed at evaluating the potential of a cost-effective lipid material, crude soybean lecithin (CL), to co-encapsulate RIF and INH for liposomal dual delivery. RIF was encapsulated in CL-liposomes with/without cholesterol using film hydration method, after which INH was incorporated using a freeze–thawing technique. Dynamic light scattering, differential scanning calorimetry, X-ray diffraction and dialysis were used for liposome characterization. Liposomes containing CL alone (CLL) exhibited 90 % encapsulation efficiency for RIF and 59 % for INH. The mean size and surface charge of CLL were 1114 nm and –63 mV, respectively. In addition, CLL showed a controlled release profile for the co-encapsulated drugs. CLL would be promising vehicles for macrophage-targeting drug delivery. The present findings demonstrate the feasibility of using CL for preparation of combination products for liposomal delivery.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67462925","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: 4

Speciation Study of L-ascorbic Acid and its Chelated Cu(II) & Ni(II) Complexes: an Experimental and Theoretical Model of Complex Formation l -抗坏血酸及其螯合Cu(II)和Ni(II)配合物的形态研究:配合物形成的实验和理论模型

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/v72a30

Sujay Mahata, Ishani Mitra, Subhajit Mukherjee, Reddy B. Venkata Pera, G. Ghosh, W. Linert, Sankar Ch. Moi

{"title":"Speciation Study of L-ascorbic Acid and its Chelated Cu(II) & Ni(II) Complexes: an Experimental and Theoretical Model of Complex Formation","authors":"Sujay Mahata, Ishani Mitra, Subhajit Mukherjee, Reddy B. Venkata Pera, G. Ghosh, W. Linert, Sankar Ch. Moi","doi":"10.17159/0379-4350/2019/v72a30","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/v72a30","url":null,"abstract":"Different species of L-ascorbic acid and their corresponding complex formation ability with Cu(II) and Ni(II) metal ions in aqueous medium has been studied in the pH range from 2.0–12.5. The stability constants of different complexes of Cu(II) and Ni(II) with the bidentate ligand, L-ascorbic acid were determined theoretically using MINIQUARD software. Speciation of ligand and complex of Cu(II)/Ni(II) ascorbate were experimentally investigated by the titration method in solution within this pH range. Different Cu (II) and Ni(II)-L-ascorbic acid species percentages with variation of pH were calculated within the studied pH range with the help of another computer programs SIM and SPECIES. Different species distribution diagrams and the equilibria for the formation of the species were also investigated and at higher pH, ML2 species was found to be the major species in the case of both the metal complexes. All the theoretical possible structures of Cu(II) and Ni(II) complexes with L-ascorbic acid were optimized and square pyramidal and square planer geometry have been evaluated for Cu(II) and Ni(II) respectively by Gaussian09 software. Their corresponding HOMO-LUMO energy and reactivity parameters such as chemical hardness (ç), ionization potential (I), electron affinity (A), electro negativity (÷), chemical potential (ì), electrophilicity index (ù) have been calculated in order to provide a better understanding of the electronic structure of complexes with the experimental results.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67463184","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: 5

2,4-Dioxo-1,3-diazaspiro[4,5]decane-3-sulfonic Acid as a Novel Solid Phase Halogen-free Acid Catalyst: Preparation, Characterization and Evaluation 2,4-二氧基-1,3-重氮斯皮罗[4,5]癸烷-3-磺酸作为新型固相无卤酸催化剂的制备、表征及评价

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/v72a25

Behzad Khalil, Aref Atashrazm, Mona Rasoulian

引用次数: 0

Un-functionalized Gold Nanoparticles as a Simple Colorimetric Probe for Sensitive and Selective Detection of Dopamine 非功能化金纳米颗粒作为一种简单的比色探针用于多巴胺的敏感和选择性检测

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/v72a27

Nokuthula Khanyile, R. Krause, Sibulelo L. Vilakazi, N. Torto

引用次数: 2

Structural Characterization and Thermal Properties of the Anti-malarial Drug: Lumefantrine 抗疟疾药物氟苯曲明的结构表征和热性能

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/v72a33

P. Pansuriya, G. E. Maguire, H. Friedrich

引用次数: 2

Kinetic Approach to Determine 3-Amino Methyl Hexanoic Acid in Pharmaceutical Formulations 药物制剂中3-氨基甲基己酸的动力学测定方法

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/v72a24

F. Siddiqui, Nawab Sher, Asia Naz, Najmul Hasan, S. N. Shah, Muhamad Shehzad

{"title":"Kinetic Approach to Determine 3-Amino Methyl Hexanoic Acid in Pharmaceutical Formulations","authors":"F. Siddiqui, Nawab Sher, Asia Naz, Najmul Hasan, S. N. Shah, Muhamad Shehzad","doi":"10.17159/0379-4350/2019/v72a24","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/v72a24","url":null,"abstract":"A simple and sensitive colorimetric spectrophotometric method based on application of chemical kinetics was produced and developed for the quantitative determination of 3-amino methyl hexanoic acid (pregabalin) in bulk and pharmaceutical preparations. Ninhydrin, a chromogenic agent was reacted with pregabalin at 70 °C and the absorbance was measured at 575 nm and kinetic correlation was evaluated between absorbance and time. The initial-rate, rate-constant and fixed-time (80 min) methods were employed for the estimation of pregabalin in the range of 10–30 μg mL which showed good correlation >0.9990 in all three cases with LOQ values ranging from 1.2–1.5 μg mLand LOD values ranging from 0.76–0.95 μg mL. Method validation was carried out using ICH recommendations and the variables were evaluated and optimized. The newly developed method has useful applications to determine pregabalin in pharmaceutical formulation with good recovery (98.38 to 102.12 %t) and precision (RSD < 1.4 %). Standard free energy changes and association constant were found to be 1.212 × 10 and –4.747, respectively, as determined by the Benesi–Hildebrand equation.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67463488","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

Solvent Extraction of a South African Bituminous Coal using a Model Biomass-derived Phenolic Mixture 使用模型生物质衍生酚醛混合物萃取南非烟煤

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/v72a31

Thabo Z. Sehume, C. Strydom, J. Bunt, H. Schobert

{"title":"Solvent Extraction of a South African Bituminous Coal using a Model Biomass-derived Phenolic Mixture","authors":"Thabo Z. Sehume, C. Strydom, J. Bunt, H. Schobert","doi":"10.17159/0379-4350/2019/v72a31","DOIUrl":"https://doi.org/10.17159/0379-4350/2019/v72a31","url":null,"abstract":"A model biomass-derived phenolic mixture was investigated for its solvent ability for extraction of a South African bituminous coal at temperatures of 300–360 °C. A previous study showed that phenol gave the highest extraction yield of 49.5 wt. % (daf) for bituminous coal at 360 °C, with an oil yield of 26.3 wt. % (daf). The phenolic products produced from sweet sorghum bagasse via an alkaline liquefaction process were identified and reported earlier and a model biomass-derived phenolic mixture was formulated, evaluated and results used in this study. The model mixture gave an extraction yield of 37.1 wt. % (daf) and oil yield of 16.9 wt. % (daf) at 360 °C. This solvent mixture was found to be less effective for high extraction yields when compared to phenol at mild temperatures. This could be due to phenol being a better hydrogen carrier than the solvent mixture during the internal redistribution of hydrogen in the coal. The infrared spectroscopy results of the coal and extraction products obtained using the model mixtures showed similar functional groups. These results demonstrate that the use of a model biomass-derived phenolic mixture has the potential to depolymerize coal and produce high-value chemicals from coal.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67463193","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