Middle School Graduates' Understandings of Scientific Inquiry and Its Relation to Academic Achievement.

There are conflicting reports not only on the effect of scientific inquiry on academic achievement but also insufficient evidence on the relationship between understanding the nature of scientific inquiry and academic achievement; more generalizable studies are needed. The purpose of this large sampled study was to investigate the middle school graduates' understandings of scientific inquiry (SI) and the relationship between students' understandings of SI and academic achievement. The sample of the study (X = 3067) was selected by purposeful and layered-sampling techniques among ninth grade students studying at high schools with different orientations in Istanbul. Descriptive and inferential statistical approaches were used in the data analysis procedure. The students' academic achievement was operationally defined as the scores they received in the High School Entrance Exam (HEE). Views about scientific inquiry scale was applied to determine the participants' understandings about scientific inquiry. The data were collected in the first 2 weeks of the first semester of high school in accordance with the purpose of the study. The results of the study revealed that middle school graduates generally do not have adequate understandings of SI. Furthermore, according to the findings except for the "conclusion data conformity" aspect, there are statistically significant correlations between students' academic achievement and understandings in all aspects of SI.

Proline-based organocatalyst-mediated asymmetric aldol reaction of acetone with substituted aromatic aldehydes: an experimental and theoretical study.

This work involves a facile synthesis of three (S) -proline-based organocatalysts with C2 symmetry and their effects in enantioselective aldol reaction of acetone with substituted aromatic aldehydes. Moderate enantioselectivities (up to 61% ee) were obtained depending on the nature of the substituents on the aryl ring. Computational calculations at HF/6-31 + G(d) level were employed to underline the enantioselectivity imposed by all the organocatalysts. Higher calculations at B3LYP/6-311 ++ G(d,p) scrf=(solvent=dichloromethane)//B3LYP/6-31 + G(d) levels of theory were also performed for the aldol reaction of acetone with benzaldehyde and 4-nitrobenzaldehyde catalyzed by 1. The computational outcomes were consistent with those produced by experimental results and they were valuable to elucidate the mechanism for the observed stereoselectivity.

Experimental and theoretical study of the mechanism of hydrolysis of substituted phenyl hexanoates catalysed by globin in the presence of surfactant.

The bimolecular rate constants for the globin- and alkali-catalysed hydrolysis of substituted phenyl hexanoates in the absence and presence of cetyltrimethylammonium bromide (CTAB) obey Brønsted equations with ß(lg) = -0.53 (globin-catalysed), -0.68 (globin-catalysed in CTAB), -0.34 (in water) and -0.74 (in CTAB), respectively. The slopes indicate that the microsolvation environments associated with the transition states of the catalysed reactions are different from those that occur in aqueous medium. The slope (-0.74) for the reaction in CTAB implies that it proceeds in a less polar medium. The larger ß(lg) value (-0.53) obtained for the globin-catalysed reaction compared to that for the uncatalysed one may be attributed to either the less polar microenvironments of the transition states or the involvement of one of the imidazole groups as a nucleophile. The results from a study of the effect of pH on the reactivity provide evidence for the latter assumption. All of the ligands were docked into the hydrophobic pocket of the protein, and the resulting docking scores ranged from -30.76 to -23.61 kcal mol⁻¹. Molecular dynamic simulations and MM-PBSA/GBSA calculations performed for the complexes gave insight into the binding modes of globin to the esters, which are consistent with experimental results. The calculations yielded comparable free energies of binding to the experimental ones for 4-nitrophenyl and 4-chloro-2-nitrophenyl hexanoates. In conclusion, information obtained from the linear free-energy relationship is still very useful for elucidating the mechanisms of organic reactions, including enzyme-catalysed reactions. This approach is further supported by the utilization of computational tools.

ß-Hydroxyamide-based ligands and their use in the enantioselective borane reduction of prochiral ketones.

Hydroxyamide-based ligands have occupied a considerable place in asymmetric synthesis. Here we report the synthesis of seven ß-hydroxyamide-based ligands from the reaction of 2-hydroxynicotinic acid with chiral amino alcohols and test their effect on the enantioselective reduction of aromatic prochiral ketones with borane in tetrahydofuran (THF). They produce the corresponding secondary alcohols with up to 76% enantiomeric excess (ee) and good to excellent yields (86-99%).