The purpose of this study was to investigate the development of pre-service chemistry teachers' (PCTs') argumentation skills in a laboratory course throughout a semester. A case study design was ...utilised. A total of six PCTs participated in the study. To investigate the development of PCTs' argumentation skills, the laboratory reports that were in the form of science writing heuristic and pre and post semi-structured interviews were employed. Results showed that PCTs' argumentation skills developed over time as they started to generate more powerful arguments which also included deeper conceptual knowledge during the argumentation-based laboratory. The other result of the study revealed that PCTs become successful in explaining chemistry concepts at the sub-microscopic level throughout the course.
In this study, a direct assay, a modified CUPRAC (Cupric Ion Reducing Antioxidant Capacity) method, is developed to determine transition metal ion (Cu(II))-catalyzed pro-oxidant activity of ...polyphenolic compounds, vitamins C and E, and herbal samples in the presence of proteins containing thiol groups. Since transition metal ion-catalyzed pro-oxidant activity of phenolics is usually initiated with the reduction of the metal to lower oxidation states (as a prerequisite of Fenton-type reactions), this method involves the reduction of copper(II) ions to copper(I) by polyphenolic compounds (simultaneously giving rise to reactive species), binding of the formed Cu(I) to egg white protein –SH groups, and liberation of copper(I)-neocuproine (Cu(I)-Nc) chelate (showing maximum absorbance at 450nm) by treating the incubation product with a neocuproine–ammonium acetate mixture. The proposed method is validated against atomic absorption spectrometric (AAS) determination of protein-bound copper and protein carbonyl assay of oxidative stress. The proposed assay is faster and more specific than the carbonyl assay, and uses low-cost reagents and equipment. Pro-oxidant activity (i.e. proportional to absorbance) varies linearly over a relatively wide range with concentration, as opposed to the reciprocal correlations (i.e. linear regression of 1/(pro-oxidant activity) versus 1/concentration) of other similar assays. The pro-oxidant activity order of the tested antioxidant compounds in terms of ‘Quercetin Equivalent Pro-oxidant Activity' (QREPA) coefficients is: gallic acid>epicatechin>quercetin≈catechin>α-tocopherol>rosmarinic acid>trolox>caffeic acid>ascorbic acid.
•A direct colorimetric pro-oxidant activity assay was developed for polyphenols.•Cu(II)-induced pro-oxidant action of polyphenols produces reactive species and Cu(I).•Cu(I) binds to egg white protein thiols, and is liberated by buffered neocuproine.•Pro-oxidant activity of phenolics is proportional to copper(I)-neocuproine absorbance.•Pro-oxidant activity varies linearly with antioxidant concentration, and is additive.
Display omitted
•We synthesized Ni(II), Fe(III), VO(IV) complexes of thiosemicarbazone and characterized.•The compounds were tested for in vitro antioxidant capacity using the CUPRAC method.•It was ...measured the scavenging activities of reactive oxygen species (ROS), also.•The ligand exhibited more potent in vitro antioxidant capacity than its complexes.•V(IV) and Fe(III) complexes had significant scavenging activity for ROS.
The nickel(II), iron(III), oxovanadium(IV) complexes of the 3-hydroxysalicylidene-S-methyl-thiosemicarbazone (L) were obtained from the 3-hydroxysalicyldehyde-S-methylthiosemicarbazone with the R1-substituted-salicylaldehyde (R1: H, 3-OH) in the presence of Ni(II), Fe(III), VO(IV) as template ion. The ligand and its complexes were characterized by elemental analysis, electronic, UV/Vis., 1HNMR, EPR and IR studies. The free ligand and its metal complexes have been tested for in vitro antioxidant capacity by reduction of copper(II) neocuproine (Cu(II)-Nc) using the CUPRAC method. The ligand exhibited more potent in vitro antioxidant capacity than its complexes. The obtained trolox equivalent antioxidant capacity (TEAC) value of the iron(III) complex (TEACCUPRAC=3.27) was higher than those of other complexes. Furthermore, the antioxidant activity of the free ligand and its complexes were determined by in vitro methods measuring the scavenging activity of reactive oxygen species (ROS) including hydroxyl radical (OH), superoxide anion radical (O2−), and hydrogen peroxide (H2O2), showing that especially the V(IV) and Fe(III) complexes had significant scavenging activity for ROS.
The nickel(II), iron(III) and oxovanadium(IV) complexes of the N2O2 chelating thiosemicarbazones were synthesized using 4-hydroxysalicyldehyde-S-methylthiosemicarbazone and ...R1-substitute-salicylaldehyde (R1: 4-OH, H) in the presence of Ni(II), Fe(III),VO(IV) by the template reaction. The structures of thiosemicarbazone complexes were characterized by FT-IR, 1H NMR, elemental, ESI-MS and APCI-MS analysis. The synthesized compounds were screened for their antioxidant capacity by using the cupric reducing antioxidant capacity (CUPRAC) method. Trolox equivalent antioxidant capacity (TEAC) of iron(III) complex, 1c, was measured to be higher than that of the other complexes. Other parameters of antioxidant activity (scavenging effects on OH, O2− and H2O2) of these compounds were also determined. All the compounds have shown encouraging ROS scavenging activities. Display omitted
•New N2O2 chelating thiosemicarbazones synthesized by template method.•The synthesized compounds were screened for their antioxidant capacity by CUPRAC method.•All compounds exhibited powerful HPS and SRSA in comparison with trolox at very low concentrations.
The nickel(II), iron(III) and oxovanadium(IV) complexes of the N2O2 chelating thiosemicarbazones were synthesized using 4-hydroxysalicyladehyde-S-methylthiosemicarbazone and R1-substitute-salicylaldehyde (R1: 4-OH, H) in the presence of Ni(II), Fe(III), VO(IV) ions by the template reaction. The structures of the thiosemicarbazone complexes were characterized by FT-IR, 1H NMR, elemental, ESI-MS and APCI-MS analysis. The synthesized compounds were screened for their antioxidant capacity by using the cupric reducing antioxidant capacity (CUPRAC) method. Trolox equivalent antioxidant capacity (TEAC) of iron(III) complex, 1c, was measured to be higher than that of the other complexes. Other parameters of antioxidant activity (scavenging effects on OH, O2− and H2O2) of these compounds were also determined. All the compounds have shown encouraging ROS scavenging activities.
This study investigated pre-service chemistry teachers' pedagogical content knowledge of the nature of science (NOS) in the content of the particle nature of matter. Qualitative research design was ...utilized. Data were collected from seven pre-service chemistry teachers (PCTs) by using open-ended questions, interviews, observations, lesson plans, and reflection papers. The results indicated that while most of the PCTs showed improvement in terms of understanding of the target aspects of NOS, knowledge of learners and instructional strategies, the majority of PCTs did not make progress regarding knowledge of assessment during the study. Implications for science teacher education are also presented.
First Aid is a set of applications that require rapid intervention with the facilities at the scene in emergency emergencies. Serious disability and death may occur if the applications are performed ...unconsciously. In order to apply a conscious first aid, the first aid should include; knowledge, skills, calm and self-confidence. The most basic element in gaining these features is education. Trainings should encourage the individual, gain skills and be designed to be real. The “Training on Basic Life Support Application Awareness Training with Theater” project focuses on the insufficiency of the applications that must be done by the people at the scene in the first minutes after the incident before ambulance and hospital interventions. With the trainings within the scope of the project, it is aimed to create awareness of life saving chain. The project consists of different stages. In every stage, the applications that should andshould not be done are emphasized. 677 people have been reached in 27 awareness trainings that are carried out within the scope of the project, mostly between January and September 2019, in the Aegean Region. In the evaluation made after the training, thesatisfaction score was 96%. The self-confidence rate of the participants regarding the sudden cardiac arrest before and after the training was evaluated. As a result; Basic Life Support awareness trainings should be expanded and the society should be madeconscious
PDF