Functional Group Effects of New Calixarene Derivatives on Catalytic and Enantioselective Behavior of Lipase

ABSTRACT

In this study, two new calixarene derivatives bearing thiourea and carbamate moieties were synthesized and characterized. Moreover, thiourea- and carbamate-bridged calixarene derivatives with Fe₃O₄ magnetic nanoparticle were employed for the first time as the convenient additives in the encapsulation process of lipase. The results of catalytic activity and enantioselectivity of the encapsulated lipases in the hydrolysis reaction of racemic flurbiprofen methyl ester indicate that both of the encapsulated lipases (Enc-TuC[4]@Fe₃O₄ and Enc-CbC[4]@Fe₃O₄) exhibit higher conversion and enantioselectivity compared to the free-encapsulated lipase (Enc-Lipase). However, the highest affinities result was obtained when the encapsulated lipase (Enc-CbC[4]@Fe₃O₄) was used in the kinetic resolution reaction of racemic flurbiprofen methyl ester.     

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.     

The effects of long-term storage on the cold flow properties and viscosity of canola-based biodiesel

In this study, the effects of long-term storage on the viscosity and cold flow properties of biodiesel were investigated. Canola oil with a high content of unsaturated fatty acid was used to produce biodiesel in the experiments. Biodiesel sample was kept in ordinary atmospheric storage conditions for 6 months. The samples were taken from the biodiesel feedstock in every 30 days and cold flow properties and kinematic viscosity of the samples were measured. During 6-month storage, no significant deterioration was observed in cold flow properties and kinematic viscosity of biodiesel. Additionally, the same pour point (PP) and cold filter plugging point (CFPP) values (?11°C) were obtained during this period.     

Effects of different polymerization protocols on the degree of conversion of two dual‐cured core buildup composites polymerized by light‐emitting diode and halogen light‐curing units

The aim of study was to investigate the effects of various curing protocols with quartz–tungsten halogen (QTH) or light‐emitting diode (LED) light‐curing units on the degree of conversion (% DC) of two dual‐cured core buildup resin composites. Two dual‐cured core buildup resin composites, Clearfil Dc Core Automix (CLF) and Grandio Core Dc (GR), were selected. Specimens were exposed to the polymerization protocols as follows: there was immediate photoactivation or photoactivation delayed by 2 or 5 min by a QTH or LED source, and one group was allowed to chemically polymerize and served as a control (n = 6). The % DC of the specimens was determined with attenuated total reflectance–Fourier transform infrared spectroscopy. The GR samples polymerized with QTH for the 5‐min‐delayed photoactivation had higher % DC values than those self‐cured, and the Clearfil Dc Core Automix (CLF) samples with immediate or delayed curing protocols with halogen yielded higher % DC values than the samples that were chemically polymerized. The comparison of the two resin composites polymerized with halogen showed a higher % DC for CLF than for GR in the 2‐min‐delayed photoactivation. On the other hand, when they were cured with LED, the % DC values of GR significantly increased after the 2‐min‐delayed photoactivation. In light of the results, it might be stated that CLF polymerized with QTH, could be the better option. GR provided adequate chemical polymerization; therefore, it might be useful in areas in which light curing is not possible. Clinicians should consider the polymerization characteristics of dual‐cured resin composites. The use of different composites may require the modification of the application procedures recommended by the manufacturer. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40560.     

Steam reforming of ethanol with zirconia incorporated mesoporous silicate supported catalysts

Steam reforming of ethanol is a promising route for the production of high purity hydrogen. Ni impregnated zirconia, with high chemical and thermal stability and high water adsorption-dissociation capability is an attractive catalyst for this reaction. In the present study, mesoporous zirconia and high surface area zirconia/silicate structured materials, such as Zr-SBA-15 and Zr-MCM-41, were synthesized following hydrothermal routes, using different surfactants as the structure directing templates. Surface area values of Ni impregnated mesoporous Zr-SBA-15 and Zr-MCM-41 catalysts with molar Zr/Si ratios of 0.13 and 0.45 were 515 and 338 m²/g, respectively. Ethanol reforming tests performed with these catalysts, in the temperature range of 550–650 °C, proved the potential of these materials to achieve very high hydrogen yields, over 90% of the maximum yield value of 6 mol per mole of ethanol reacted. Type of support material, Ni distribution and cluster size over the catalyst, reaction temperature and steam to ethanol ratio were found to have strong influence on coke formation and stability of hydrogen yield.     

Effect of yarn properties on thermal comfort of knitted fabrics

In this research, thermal properties of 1×1 rib fabrics knitted by using various yarns of different properties were investigated with all details. The mentioned yarn properties were yarn count, yarn twist and combing process. The thermal resistance, thermal absorptivity, thermal conductivity, water vapour permeability of samples were measured with the aid of Alambeta and Permetest devices respectively. The results of the tests were evaluated statistically and the importance levels of the relationship between the measured parameters were determined. It is observed that yarn properties like yarn count, yarn twist and combing process of cotton have affected different thermal comfort properties of 1×1 rib knitted fabrics. While the yarn twist and yarn count increase thermal resistance values decrease and water vapour permeability values increase. The combing process has the same effect on the thermal properties.     

Comparison of antioxidant capacity of cow and ewe milk kefirs

This research aimed to evaluate the effects of using either grain or commercial starter culture on the antioxidative capacity of cow and ewe milk kefirs. The antioxidant capacity of kefir samples during fermentation and 21 d of storage was assessed by using 3 assays: 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical cation decolorization; 2,2-diphenyl-1-picrylhydrazyl (DPPH^?) radical scavenging activity assay; and Fe⁺³-reducing power (ferric reducing antioxidant power assay, FRAP). Vitamin E and β-carotene contents were also quantified. All kefir samples exhibited varying values for DPPH, ABTS, and FRAP assays depending on the starter culture and milk type. Vitamin E and β-carotene contents were similar in all kefir samples during storage. The results of this study suggest that milk type (cow or ewe) and culture type (kefir grains or commercial starter) were the significant parameters for the antioxidative activity of kefir.     

Influence of inulin and demineralised whey powder addition on the organic acid profiles of probiotic yoghurts

In this study, the effect of the different concentrations of inulin and demineralised whey (d‐whey) powder on the chemical characteristics and organic acid profiles of probiotic yoghurts were investigated. Analysis of chemical composition was performed on the first day, while pH and organic acid profiles were carried out during storage. The results indicated that different proportions of inulin and d‐whey powder significantly influenced the levels of the organic acids, produced while the duration of storage affected the orotic, pyruvic, citric, lactic and acetic acid levels. There was a direct relationship between the level of d‐whey powder and organic acid (except for butyric acid) concentration in the probiotic yoghurt.     

Experimental and Numerical Investigation of Inlet Temperature Effect on Convective Heat Transfer of γ-Al2O3/Water Nanofluid Flows in Microtubes

ABSTRACT

Nanofluids are the combination of a base fluid with nanoparticles with sizes of 1–100 nm. In order to increase the heat transfer performance, nanoparticles with higher thermal conductivity compared to that of base fluid are introduced into the base fluid. Main parameters affecting single-phase and two-phase heat transfer of nanofluids are shape, material type and average diameter of nanoparticles, mass fraction and stability of nanoparticles, surface roughness, and fluid inlet temperature. In this study, the effect of inlet temperature of deionized water/alumina (Al₂O₃) nanoparticle nanofluids was both experimentally and numerically investigated. Nanofluids with a mass fraction of 0.1% were tested inside a microtube having inner and outer diameters of 889 and 1,067 µm, respectively, for hydrodynamically developed and thermally developing laminar flows at Reynolds numbers of 650, 1,000, and 1,300. According to the obtained numerical and experimental results, the inlet temperature effect was more pronounced for the thermally developing region. The performance enhancement with nanoparticles was obtained at rather higher Reynolds numbers and near the inlet of the microtube. There was a good agreement between the experimental and numerical results so that the numerical approach could be further implemented in future studies on nanofluid flows.