Design,Synthesis, and Biological Evaluation of Pyridazinones Containing the (2-Fluorophenyl) Piperazine Moiety as Selective MAO-B Inhibitors

Twelve pyridazinones (T1–T12) containing the (2-fluorophenyl) piperazine moiety were designed, synthesized, and evaluated for monoamine oxidase (MAO) -A and -B inhibitory activities. T6 was found to be the most potent MAO-B inhibitor with an IC₅₀ value of 0.013 µM, followed by T3 (IC₅₀ = 0.039 µM). Inhibitory potency for MAO-B was more enhanced by meta bromo substitution (T6) than by para bromo substitution (T7). For para substitution, inhibitory potencies for MAO-B were as follows: -Cl (T3) > -N(CH₃)₂ (T12) > -OCH₃ (T9) > Br (T7) > F (T5) > -CH₃ (T11) > -H (T1). T6 and T3 efficiently inhibited MAO-A with IC₅₀ values of 1.57 and 4.19 µM and had the highest selectivity indices (SIs) for MAO-B (120.8 and 107.4, respectively). T3 and T6 were found to be reversible and competitive inhibitors of MAO-B with K_i values of 0.014 and 0.0071, respectively. Moreover, T6 was less toxic to healthy fibroblast cells (L929) than T3. Molecular docking simulations with MAO binding sites returned higher docking scores for T6 and T3 with MAO-B than with MAO-A. These results suggest that T3 and T6 are selective, reversible, and competitive inhibitors of MAO-B and should be considered lead candidates for the treatment of neurodegenerative disorders like Alzheimer’s disease.     

Evaluating students’ conceptual and procedural understanding of sampling distributions

Introductory statistics courses, which are important in preparing students for their daily lives, generally derive inferential statistics from informal knowledge. In this transition process, sampling distributions have an important place, yet research has shown that students often have difficulties with this concept. In order to increase their understanding of sampling distributions, students should have a strong conceptual foundation that is balanced with procedural knowledge. To address this issue, this study was designed to examine the relationship between college students’ procedural and conceptual knowledge of sampling distributions. With this aim in mind, an achievement test consisting of two sections – procedural and conceptual knowledge – was prepared. In answering the questions related to procedural knowledge, the participants were more successful in identifying the relationship between standard deviation of a population and sample means. However, they lacked theoretical knowledge about statements that they had heard or knew intuitively. Simulation activities provided in statistics courses may support students in developing their conceptual understanding in this regard.     

A monostyryl-boradiazaindacene (BODIPY) derivative as colorimetric and fluorescent probe for cyanide ions

We developed a novel boradiazaindacene derivative to detect cyanide ions in solution at micromolar concentrations. This structurally simple chemosensor displays a large decrease in emission intensity and a reversible color change from red to blue on contact with cyanide ions. Highly fluorescent polymeric films can be obtained by doping with the chemosensor. Such polymeric materials can be used for the sensing of the cyanide ions in polymer matrices.     

Monodisperse Mw-Pt NPs@VC as Highly Efficient and Reusable Adsorbents for Methylene Blue Removal

Addressed herein, monodisperse Vulcan carbon supported Pt nanoparticles (Mw-Pt NPs@VC) have been reproducibly synthesized using the microwave assisted method and their application for methylene blue (MB) removal from aqueous solutions was investigated through the adsorption mechanism. The prepared nanomaterials were characterized by X-ray diffraction, transmission electron microscopy, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy. All results show that highly crystalline and colloidally stable nanoparticles have been formed and Mw-Pt NPs@VC were found to be one of the the most active catalyst. The results showed that the Mw-Pt NPs@VC nanoparticles had remarkable MB adsorption capacity of 271.15 mg/g. The equilibrium for MB adsorption was attained in ～55 min. Moreover, Mw-Pt NPs@VC is a reusable and promising material for MB removal since it preserves 95.6 % of its initial efficiency after six successive cycles of adsorption–desorption.     

Entropy‐Driven Selectivity for Chain Scission: Where Macromolecules Cleave

We show that, all other conditions being equal, bond cleavage in the middle of molecules is entropically much more favored than bond cleavage at the end. Multiple experimental and theoretical approaches have been used to study the selectivity for bond cleavage or dissociation in the middle versus the end of both covalent and supramolecular adducts and the extensive implications for other fields of chemistry including, e.g., chain transfer, polymer degradation, and control agent addition are discussed. The observed effects, which are a consequence of the underlying entropic factors, were predicted on the basis of simple theoretical models and demonstrated via high‐temperature (HT) NMR spectroscopy of self‐assembled supramolecular diblock systems as well as temperature‐dependent size‐exclusion chromatography (TD SEC) of covalently bonded Diels–Alder step‐growth polymers.     

Problem types used in math lessons: the relationship between student achievement and teacher preferences

The purpose of this study was to determine the relationship between the problems teachers preferred in mathematics lessons and student achievement in different types of problems. In accordance with this purpose, nine mathematics teachers were interviewed, and corresponding problems were prepared and administered to 225 eighth-grade students. The findings indicate that problem types are dependent on teacher preferences. It was found that curriculum-dependent and routine problems were dominant for teacher preferences. Students are more successful at with missing data, problems that are visual and do not require the use of different strategies. They have lower success at long problems, those that contain irrelevant data, problems that require the use of different strategies and difficult problem types. It was found that problem types at which students were successful and which teachers preferred were related. These results relay information about problems used in the learning environment and effect of problem-solving experiences on students' success.     

Oxidation of di-n-propyl ether: Characterization of low-temperature products

The oxidation of di-n-propyl-ether (DPE) was performed in a jet-stirred reactor at 1 and 10 atm, at residence times of 1 and 0.7 s, respectively, and initial fuel concentrations of 5000 and 1000 ppm at 1 and 10 atm, respectively. Atmospheric pressure experiments were used for characterization of cool flame products. The 10 atm experiment provided KHPs profile vs. temperature and mole fraction profiles of stable species which were obtained through sonic probe sampling, gas chromatography, Fourier transform infrared spectrometry analyses. High resolution mass spectrometry analyses (HRMS) with syringe direct injection or ultra-high-pressure liquid chromatography coupling was used to characterize hydroperoxides (C₃H₈O₂, C₆H₁₄O₃), diols (C₆H₁₄O₃), ketohydroperoxides (C₆H₁₂O₄), carboxylic acids, and highly oxygenated molecules (C₆H₁₂O₆, C₆H₁₂O₈) resulting from up to four O₂ additions on fuel's radicals. Heated electrospray and atmospheric pressure chemical ionizations (HESI and APCI) were used in positive and negative mode. Whereas the CH₂ groups neighboring the ether function are the most favorable sites for H-atom abstraction reactions, speciation indicated that other sites can react by metathesis forming a large pool of intermediates. Our kinetic reaction mechanism represents the experimental data for most of the stable species but need to be expended for simulating the formation of newly detected species.     

Oxidation of pentan-2-ol – Part I: Theoretical investigation on the decomposition and isomerization reactions of pentan-2-ol radicals

Theoretical investigations on the kinetics of pentan-2-ol radical decomposition and isomerization reactions have been carried out in this work, together with the thermochemistry data calculations for important species involved in the reaction process. The B2PLYPD3/6-311++G(d,p) level of theory was used to optimize the geometries of all of the reactants, transition states, products and also the hindered rotor treatment for lower frequency modes. Single-point energies of all species are determined at the ROCCSD(T) level using the cc-PVQZ and cc-pVTZ which were extrapolated to the complete basis set limit (CBS). RRKM/Master Equation has been solved to calculate the pressure- and temperature-dependent rate coefficients for all channels in the pressure range of 0.01–100 atm over 300–2000 K. Pressure and temperature dependent branching fractions of key species produced from different pentan-2-ol radicals shows that 1- and 2-pentene are important bimolecular products. The kinetics and thermochemistry data for the title reactions has been used in the part II of this work for model development for pentan-2-ol oxidation.     

Microwave-assisted dilute acid pretreatment of different agricultural bioresources for fermentable sugar production

Microwave-assisted pretreatment can be used for fermentable sugar production from lignocellulosic biomass. In this study, the optimum hydrolysis conditions of barley husk, oat husk, wheat bran, and rye bran were determined in power level, treatment time, solid-to-liquid ratio and dilute acid ratio as follows: 700 W, 6.92 min, 1:18.26 w/v, and 3.67% for barley husk, 600 W, 6.96 min, 1:17.22 w/v, and 3.47% for oat husk, 600 W, 6.92 min, 1:16.69 w/v, and 1.85% for wheat bran, and 460 W, 6.15 min, 1:17.14 w/v, and 2.72% for rye bran. The fermentable sugar concentrations were 37.21 (0.68 g/g), 38.84 (0.67 g/g), 49.65 (0.83 g/g), and 36.27 g/L (0.62 g/g) under optimum conditions, respectively. The results showed that microwave-assisted pretreatment is a promising technology which can be successfully implemented for the hydrolysis of lignocellulosic biomass for high sugar yield. On the other hand, hydrolysates included some inhibitors such as organic acids, furans, and phenolic compounds. Lignocellulosic biomass used in this study can be employed as good feedstocks for value-added product production in the fermentation process, after the inhibitors have been detoxified/removed with different detoxification methods.