206 research outputs found
Perceptual Learning Styles and Critical Thinking: Inspecting the Association among EFL Learners
Influenced by the acknowledged role of critical thinking and learning styles in the process of second language learning, this study attempted to systematically inspect the association between English as a Foreign Language (EFL) learners' critical thinking, on one hand, and their total score of perceptual learning styles, different perceptual learning styles, and number of major perceptual learning styles, on the other hand. To do so, 595 male and female undergraduate EFL learners, between the ages of 18 and 25 (Mage = 22) participated in this study. These participants completed two instruments: a) the questionnaire of critical thinking by Honey (2000), and b) the Perceptual Learning Style Preference Survey developed by Reid (1984). Due to the violation of the assumptions of normality of distribution, the non-parametric Spearman rank order coefficient of correlation was employed in order to answer the initial 3 research questions. The obtained results indicated that there were significant and positive relationships between participants’ critical thinking and total score of perceptual learning styles, ρ = .33, n = 595, p < .01; critical thinking and the number of major perceptual learning styles, ρ = .28, n = 595, p < .01; and critical thinking and group, visual, auditory, tactile, and kinesthetic perceptual learning styles. Furthermore, a multiple regression analysis was run which revealed that tactile learning style preference is the best predictor of EFL learners’ critical thinking (β = 0.285, t = 6.107, p = 0.0005). The study concludes with a discussion on the findings and stating a number of recommendations for further research
Novel 2D coordination polymers of La(III) and Ce(III), doped with Eu(III), Tb(III), Sm(III) and Dy(III) : synthesis and luminescence properties
Novel 2D coordination polymers of La(III) and Ce(III), doped with Eu(III), Tb(III), Sm(III) and Dy(III): synthesis, crystal structures and luminescence properties
Poly[μ2-aqua-aqua-μ4-pyridine-2,4-dicarboxylato-strontium]
In the title polymeric complex, [Sr(C7H3NO4)(H2O)2]n, the SrII atom is eight-coordinated by four O atoms and one N atom of four pyridine-2,4-dicarboxylate (py-2,4-dc) ligands and three O atoms of three coordinated water molecules in a dodecahedral geometry. These units are connected via the carboxylate O atoms and water molecules, building polymeric layers parallel to (100). In the crystal structure, non-covalent interactions consisting of O—H⋯O hydrogen bonds and π–π stacking interactions [centroid–centroid distances = 3.862 (17) and 3.749 (17) Å] connect the various components, forming a three-dimensional structure
2,6-Diaminopyridinium bis(4-hydroxypyridine-2,6-dicarboxylato-κ3 O 2,N,O 6)chromate(III) dihydrate
The reaction of chromium(III) nitrate hexahydrate, pyridine-2,6-diamine and 4-hydroxypyridine-2,6-dicarboxylic acid in a 1:2:2 molar ratio in aqueous solution resulted in the formation of the title compound, (C5H8N3)[Cr(C7H3NO5)2]·2H2O or (pydaH)[Cr(hypydc)2]·2H2O (where pyda is pyridine-2,6-diamine and hypydcH2 is 4-hydroxypyridine-2,6-dicarboxylic acid). Each CrIII atom is hexacoordinated by four O and two N atoms from two (hypydc)2− fragments, which act as tridentate ligands, in a distorted octahedral geometry. The O—Cr—O—C torsion angles between the two planes of the (hypydc)2− fragments [−99.81 (17) and 97.77 (17)°] indicate that these two units are almost perpendicular to one another. In the crystal structure, extensive O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds with D⋯A distances ranging from 2.560 (2) to 3.279 (3) Å, ion pairing, C—O⋯π [O⋯π = 3.166 (2) Å] and π–π stacking interactions between (hypydc)2− and (pydaH)+ rings [with a centroid–centroid distance of 3.3353 (14) Å] contribute to the formation of a three-dimensional supramolecular structure
4,4′-Bipyridinium bis(μ-4-oxo-1,4-dihydropyridine-2,6-dicarboxylato)bis[aquahydroxidoantimonate(III)] dihydrate
The title compound, (C10H10N2)[Sb2(C7H2NO5)2(OH)2(H2O)2]·2H2O, consists of a binuclear anion, a diprotonated 4,4′-bipyridinium cation and two uncoordinated water molecules. Each SbIII atom is six-coordinated by one chelating 4-oxidopyridine-2,6-dicarboxylate ligand, one water molecule, one OH group and one bridging O atom from a neighboring carboxylate group in a distorted pentagonal-pyramidal geometry, with the OH group at the apical position. The two pyridine rings in the bipyridinium cation are twisted with respect to each other, making a dihedral angle of 22.7 (1)°. The cations are connected to the anions by N—H⋯O hydrogen bonds, forming a chain. The coordinated water molecules form hydrogen bonds with the oxido O atoms of the anion, building a two-dimensional sheet, which is further connected into a three-dimensional structure by O—H⋯O and C—H⋯O hydrogen bonds and C=O⋯π interactions [O⋯centroid distances = 3.1785 (17), 3.4737 (19) and 3.5685 (19) Å]
Effect of Rickettsiella viridis endosymbionts introduced into Myzus persicae aphids on parasitism by Diaeretiella rapae:A combined strategy for aphid control?
Aphids are major crop pests in southeastern regions of Australia. Some aphid species harbor heritable facultative endosymbionts that may induce beneficial or detrimental impacts on aphids under certain ecological conditions. Aphid-parasitoid interactions can be greatly affected by facultative endosymbionts but there is still limited research on many species of economic significance. Here we assessed the effects of a facultative endosymbiont, Ricketsiella viridis, on parasitism of the major aphid pest, Myzus persicae, by Diaeretiella rapae. We found that R. viridis does not provide M. persicae with significant protection against D. rapae, with parasitoids showing a preference for probing aphids infected with R. viridis. The fecundity of M. persicae is reduced due to infection with R. viridis regardless of the presence of parasitoids. Moreover, we show that parasitoids may facilitate horizontal and subsequent vertical transmission of facultative endosymbionts in aphids which could increase the spread of deleterious effects associated with R. viridis. Based on these findings, simultaneous release of D. rapae and M. persicae infected with R. viridis in the early cropping season (lower population densities and cooler conditions) may contribute to an effective strategy for efficient management of this pest.</p
Sensitizing, sensing and chemical separation of Tb(III) ions: All in a novel T copper metal-organic framework
The importance of rare earth elements in high-tech materials has promoted the necessity to develop new materials for sensing and separating them. Luminescent metal-organic frameworks (MOFs) due to their promising applications as functional materials for chemical sensing and separation, which upon introducing analytes create multi-responsive systems, have been receiving great attention by scientists. In this regard, we have designed and synthesized a novel three-dimensional copper framework, [Cu2(3,4-pydc)2(H2O)5]n.2nH2O (1; 3,4-H2pydc = 3,4-pyridine dicarboxylic acid), in ambient condition with an interesting topology and potential application as a cation exchange material. Upon Tb3+ ions uptake, compound 1 exhibited the antenna effect to sensitize Tb3+ ions and its fluorescent emission was enhanced. It also showed selective sensing ability based on turn-on fluorescence response towards Tb3+ ions, in a mixture of main and transition metal ions and Tb3+ ions. Furthermore, the results showed that the Tb3+ ion exchange process is reversible. Therefore, compound 1 is a promising multifunctional luminescent MOF for simultaneous sensing and chemical separation of Tb3+ ions which is an advantage over the previously used MOFs in this regard. Furthermore, the reusability experiment demonstrated that 1 can be utilized for long-term detection and separation of Tb3+ ions
4,4′-Bipyridine-1,1′-diium 2,3,5,6-tetrabromoterephthalate dihydrate
The title compound, C10H10N2
2+·C8Br4O4
2−·2H2O, consists of a tetrabromoterephthalate dianion, a 4,4′-bipyridinium dication and two solvent water molecules. Crystallographic inversion centers are situated at the center of the aromatic ring of the dianion as well as at the midpoint of the carbon–carbon bond connecting the pyridine rings in the dication. In the crystal, intermolecular N—H⋯O hydrogen-bonding interactions between tetrabromoterephthalate dianions and protonated 4,4′-bipyridinium dications result in the formation of a chain-like structure. Further O—H⋯O hydrogen bonds between carboxylate O atoms and water molecules lead to the formation of a two-dimensional network in the crystal structure
Sensitizing, sensing and chemical separation of Tb(III) ions: All in a novel T copper metal-organic framework
The importance of rare earth elements in high-tech materials has promoted the necessity to develop new materials for sensing and separating them. Luminescent metal-organic frameworks (MOFs) due to their promising applications as functional materials for chemical sensing and separation, which upon introducing analytes create multi-responsive systems, have been receiving great attention by scientists. In this regard, we have designed and synthesized a novel three-dimensional copper framework, [Cu2(3,4-pydc)2(H2O)5]n.2nH2O (1; 3,4-H2pydc = 3,4-pyridine dicarboxylic acid), in ambient condition with an interesting topology and potential application as a cation exchange material. Upon Tb3+ ions uptake, compound 1 exhibited the antenna effect to sensitize Tb3+ ions and its fluorescent emission was enhanced. It also showed selective sensing ability based on turn-on fluorescence response towards Tb3+ ions, in a mixture of main and transition metal ions and Tb3+ ions. Furthermore, the results showed that the Tb3+ ion exchange process is reversible. Therefore, compound 1 is a promising multifunctional luminescent MOF for simultaneous sensing and chemical separation of Tb3+ ions which is an advantage over the previously used MOFs in this regard. Furthermore, the reusability experiment demonstrated that 1 can be utilized for long-term detection and separation of Tb3+ ions
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