The effect of inquiry-based explorations in a dynamic geometry environment on sixth grade students’ achievements in polygons

The purpose of this study was to investigate the effects of using a dynamic geometry environment (DGE) together with inquiry-based explorations on the sixth grade students’ achievements in polygons and congruency and similarity of polygons. Two groups of sixth grade students were selected for this study: an experimental group composed of 66 students (34 boys and 32 girls); and a control group composed of 68 students (35 boys and 33 girls). The students in the experimental group taught with a DGE, while the students in the control group received textbook-based direct instruction. An achievement test was administered as pre-test, post-test, and delayed post-test in both groups. Qualitative data were collected through videotaped classroom observations. The results showed that the DGE together with open-ended explorations significantly improved students’ performances in polygons and congruency and similarity of polygons. Furthermore, students in the experimental group showed greater interest and motivation toward learning geometry compared to those in the control group whom often showed lack of interest and curiosity. Also, students’ comments and interpretations during lessons and tests were more accurate and advanced in the experimental group as they engage more in the DGE. Moreover, qualitative data suggested that boys showed greater interest in the computer-based learning environment than girls in the experimental groups although no significant gender effect on achievement was found.     

Effect of salep as a hydrocolloid on storage stability of ‘İncir Uyutması’ dessert

Salep is a natural stabilizing agent used widely in Turkish-type Mara? ice cream and some milk desserts. The effect of salep addition on the storage stability of a representative ?ncir Uyutmas? dessert, prepared from whole cows’ milk, fig and sugar was studied. Dry matter, pH, viscosity, water-holding capacity (WHC), color properties (L*, a*, b* values), mineral matters (Al, Ca, Cu, Fe, K, Mg, Na, P and Zn), sensorial properties and microbial quality of desserts were affected by salep addition, sugar and fig concentrations. Salep addition caused an important increase in the viscosity and the WHC of dessert. Salep, sugar and fig improved the storage stability of the dessert.     

Determination of interfacial energies of solid Sn solution in the In–Bi–Sn ternary alloy

The equilibrated grain boundary groove shapes of solid Sn solution (Sn-40.14 at.% In-16.11 at.% Bi) in equilibrium with the In–Bi–Sn liquid (In-21.23 at.% Bi-19.04 at.% Sn) were observed from the quenched sample at 59 °C. Gibbs–Thomson coefficient, solid–liquid interfacial energy and grain boundary energy of the solid Sn solution have been determined from the observed grain boundary groove shapes. The thermal conductivity of solid phase for In-21.23 at.% Bi-19.04 at.% Sn alloy and the thermal conductivity ratio of liquid phase to solid phase at the melting temperature have also been measured with radial heat flow apparatus and Bridgman type growth apparatus, respectively.     

Petrochemical wastewater treatment by means of clean electrochemical technologies

The removal of chemical oxygen demand (COD), turbidity, phenol, hydrocarbon and grease from petrochemical wastewater (PCWW) was experimentally done by using electroflotation (EF) and electrocoagulation (EC). In the EF unit, a graphite anode and a stainless steel mesh as cathode were used. In the EC unit, iron and aluminium were used simultaneously as materials for two blocks of alternating electrodes. The reactor voltage was 12 V, current density (CD) was varied from 5 to 15 mA cm^–2, and the residence time varied in the limits of 2–20 min for EF and 1–10 min for EC. The results have shown that EC removes the mentioned contaminants from PCWW more effectively than EF. Turbidity removal in the process of PCWW purification was estimated as 83% for EF and 88% for EC. The yields of phenol, hydrocarbon and grease removal by EC were examined under different values of residence time, CD, and with iron and aluminium as materials for electrodes.     

Quantifying the adhesion and interaction forces between Pseudomonas aeruginosa and natural organic matter

Atomic force microscopy (AFM) was used to characterize interactions between natural organic matter (NOM), and glass or bacteria. Poly(methacrylic acid) (PMA), soil humic Acid (SHA), and Suwannee River humic Acid (SRHA), were adsorbed to silica AFM probes. Adhesion forces (Fadh) for the interaction of organic-probes and glass slides correlated with organic molecular weight (MW), but not with radius of the organic aggregate (R), charge density (Q), or zeta potential (zeta). Two Pseudomonas aeruginosa strains with different lipopolysaccharides (LPS) were chosen: PAO1 (A+B+), whose LPS have common antigen (A-band) + O-antigen (B-band); and mutant AK1401 (A+B-). Fadh between bacteria and organics correlated with organic MW, R, and Q, but not zeta. PAO1 had lower Fadh with silica than NOM, which was attributed to negative charges from the B-band polymers causing electrostatic repulsion. AK1401 adhered stronger to silica than to the organics, perhaps because the absence of the B-band exposed underlying positively charged proteins. DLVO calculations could not explain the differences in the two bacteria or predict qualitative or quantitative trends in interaction forces in these systems. Molecular-level information from AFM studies can bring us closer to understanding the complex nature of bacterial-NOM interactions.     

Impact resistance behaviour of silicone coated warp knitted spacer fabrics used for protective clothing

This paper aims to analyse the effect of coating, fabric layers and structural parameters on the impact resistance behaviour of warp knitted spacer fabrics used for protective clothing. For this purpose, six warp knitted spacer fabrics were produced by varying thickness and mesh structure and were coated with a silicone substrate. A drop-weight impact tester was used to determine the impact resistance characteristics of the samples. The results indicate that, the impact resistance properties of warp knitted spacer fabrics can be improved considerably by coating as reducing approximately 10 kN of the peak transmitted force. Also, the structural parameters such as fabric thickness and mesh structure have significant effects on impact resistance behaviour of the samples. The fabrics with higher thickness and smaller size mesh on the outer layers have better impact resistance properties. Additionally, the lamination of spacer fabrics can effectively improve the impact resistance characteristics of the spacer fabrics. The warp knitted spacer fabrics can be used as an energy absorbing material for body protection by varying their structural parameters, fabric lamination and/or by coating.     

Modeling of ferrofluid magnetic actuation with dynamic magnetic fields in small channels

One of the most important and promising research areas in biomedical and micropumping applications is magnetic actuation of ferrofluids with dynamic magnetic fields. For ensuring the use of ferrofluids in various applications in engineering fields, their flows generated by magnetic fields should be extensively investigated and simulated. In this study, simulations of ferrofluid actuation with dynamic magnetic fields were performed by modeling it using the COMSOL Multiphysics software, and iron oxide nanoparticle-based ferrofluids at different angles of rotating magnets were considered to provide insight into ferrofluid flow in small channels. Ferrofluid flows were modeled at different magnetic flux densities provided by rotating magnets, and velocity profiles inside the channel were analyzed. It was shown that ferrofluid actuation can be considered as a futuristic micropumping alternative, simulation results matched well with the experimental results of previous work, and the established model could serve as a tool to analyze ferrofluid flows generated by dynamic magnetic fields. The results of the model show that flow rates up to 100 µl/s can be reached at a rotation angle of 30° by using dynamic magnetic fields. Various applications including biomedical applications might be envisaged.     

Does monetary support increase citation impact of scholarly papers?

Scientometrics - One of the main indicators of scientific development of a given country is the number of papers published in high impact scholarly journals. Many countries introduced...