Determination of the Protonation Constants of Some 4-(Substituted benzylamino)-4,5-dihydro- 1H-1,2,4-triazol-5-ones by the Potentiometric Method in Ethanol–Water Mixtures

To gain more information about the effect of solvent on 4,5-dihydro-1H-1,2,4-triazol-5-ones, the stoichiometric protonation constants of thirteen triazoles in ethanol–water mixtures were determined at an ionic strength of 0.10MNaCl and at 25.0±0.1 °C under nitrogen atmosphere. A potentiometric method was used and the  calculation was carried out using the PKAS computer program. The correspondingpKa values of these triazoles were determined in ethanol–water mixtures. Thus, the effects of solvent and molecular structure upon acidity were investigated. The logarithm of the protonation constants of the title 4,5-dihydro- 1H-1,2,4-triazol-5-ones decreased linearly with increasing ethanol content, but the values determined with 80% ethanol did not follow this linear trend. The variation of these constants is discussed on the basis of specific solute–solvent  interactions.KEYWORDS: Potentiometry, protonation constants, solvent effect, triazoles

SYSTEMATIC POSTSYNTHETIC MODIFICATION OF NANOPOROUS ORGANIC FRAMEWORKS AND THEIR PERFORMANCE EVALUATION FOR SELECTIVE CO2 CAPTURE

Porous organic polymers (POPs) with high physicochemical stability have attracted significant attention from the scientific community as promising platforms for small gas separation adsorbents. Although POPs have amorphous morphology in general, with the help of organic chemistry toolbox, ultrahigh surface area materials can be synthesized. In particular, nitrogen-rich POPs have been studied intensively due to their enhanced framework-CO2 interactions. Postsynthetic modification (PSM) of POPs has been instrumental for incorporating different functional groups into the pores of POPs which would increase the CO2 capture properties. We have shown that functionalizing the surface of POPs with nitro and amine groups increases the CO/N2 and CO2/CH4 selectivity significantly due to selective polarization of CO2 molecule. In addition, controlled postsynthetic nitration of NPOF-1, a nanoporous organic framework constructed by nickel(0)-catalyzed Yamamoto coupling of 1,3,5-tris(4-bromophenyl)benzene, has been performed and is proven to be a promising route to introduce nitro groups and to convert mesopores to micropores without compromising surface area. Reduction of the nitro groups yields aniline-like amine-functionalized NPOF-1-NH2. Adequate basicity of the amine functionalities leads to modest isosteric heats of adsorption for CO2, which allow for high regenerability. The unique combination of high surface area, microporous structure, and amine-functionalized pore walls enables NPOF-1-NH2 to have remarkable CO2 working capacity values for removal from landfill gas and flue gas. Benzimidazole-linked polymers have also been shown to have promising CO2 capture properties. Here, an amine functionalized benzimidazole-linked polymer (BILP-6-NH2) was synthesized via a combination of pre- and postsynthetic modification techniques in two steps. Experimental studies confirm enhanced CO2 uptake in BILP-6-NH2 compared to BILP-6, and DFT calculations were used to understand the interaction modes of CO2 with BILP-6-NH2. Using BILP-6-NH2, higher CO2 uptake and CO2/CH4 selectivity was achieved compared to BILP-6 showing that this material has a very promising working capacity and sorbent selection parameter for landfill gas separation under VSA settings. Additionally, the sorbent evaluation criteria of different classes of organic polymers have been compared in order to reveal structure-property relationships in those materials as solid CO2 adsorbents

Hofstadter butterfly of graphene with point defects

Cataloged from PDF version of article.We investigate the structure of Hofstadter's butterfly of graphene with point defects under a perpendicular magnetic field. We use a tight-binding method with interactions up to second-nearest neighbors. First of all, we present the Hofstadter butterfly spectrum of pure graphene, including all four valence orbitals with second-order hopping. To model defects, we perform calculations within an enlarged unit cell of seven carbon atoms and one defect atom. We find that impurity atoms with smaller hopping constants result in highly localized states which are decoupled from the rest of the system. The bands associated with these states form a nearly E = 0 eV line. On the other hand, impurity atoms with higher hopping constants are strongly coupled with the neighboring atoms. These states modify the Hofstadter butterfly around the minimum and maximum values of the energy by forming two self-similar bands decoupled from the original butterfly. We also show that the bands and gaps due to the impurity states are robust with respect to the second-order hopping

Hall conductance in graphene with point defects

Cataloged from PDF version of article.We investigate the Hall conductance of graphene with point defects within the Kubo formalism, which allows us to calculate the Hall conductance without constraining the Fermi energy to lie in a gap. For pure graphene, which we model using a tight-binding Hamiltonian, we recover both the usual and the anomalous integer quantum Hall effects depending on the proximity to the Dirac points. We investigate the effect of point defects on Hall conduction by considering a dilute but regular array of point defects incorporated into the graphene lattice. We extend our calculations to include next nearest neighbor hopping, which breaks the bipartite symmetry of the lattice. We find that impurity atoms which are weakly coupled to the rest of the lattice result in gradual disappearance of the high conductance value plateaus. For such impurities, especially for vacancies which are decoupled from the lattice, strong modification of the Hall conductance occurs near the E = 0 eV line, as impurity states are highly localized. In contrast, if the impurities are strongly coupled, they create additional Hall conductance plateaus at the extremum values of the spectrum, signifying separate impurity bands. Hall conductance values within the original spectrum are not strongly modified

The integer quantum Hall effect of a square lattice with an array of point defects

Cataloged from PDF version of article.The electronic properties of a square lattice under an applied perpendicular magnetic field in the presence of impurities or vacancies are investigated by the tight-binding method including up to second nearest neighbor interactions. These imperfections result in new gaps and bands in the Hofstadter butterfly even when the second order interactions break the bipartite symmetry. In addition, the whole spectrum of the Hall conduction is obtained by the Kubo formula for the corresponding cases. The results are in accordance with the Thouless-Kohmoto-Nightingale-den Nijs integers when the Fermi energy lies in an energy gap. We find that the states due to the vacancies or impurities with small hopping constants are highly localized and do not contribute to the Hall conduction. However, the impurities with high hopping constants result in new Hall plateaus with constant conduction of sigma(xy) = +/- e(2)/h, since high hopping constants increase the probability of an electron contributing to the conduction

Rational Design of Pore Size and Functionality in a Series of Isoreticular Zwitterionic Metal-Organic Frameworks

The isoreticular expansion and functionalization of charged-polarized porosity has been systematically explored by the rational design of 11 isostructural zwitterionic metal-organic frameworks (ZW-MOFs). This extended series of general structural composition {[M3F(L1)3(L2)1.5]·guests}n was prepared by employing the solvothermal reaction of Co and Ni tetrafluoroborates with a binary ligand system composed of zwitterionic pyridinium derivatives and traditional functionalized ditopic carboxylate auxiliary ligands (HL1·Cl = 1-(4-carboxyphenyl)-4,4′-bipyridinium chloride, Hcpb·Cl; or 1-(4-carboxyphenyl-3-hydroxyphenyl)-4,4′-bipyridinium chloride, Hchpb·Cl; and H2L2 = benzene-1,4-dicarboxylic acid, H2bdc; 2-aminobenzene-1,4-dicarboxylic acid, H2abdc; 2,5-dihydroxy-1,4-benzenedicarboxylic acid, H2dhbdc; biphenyl-4,4′-dicarboxylic acid, H2bpdc; or stilbene-4,4′-dicarboxylic acid, H2sdc). Single-crystal structure analyses revealed cubic crystal symmetry (I-43m, a = 31-36 Å) with a 3D pore system of significant void space (73-81%). The pore system features three types of pores being systematically tunable in size ranging from 17.4 to 18.8 Å (pore I), 8.2 to 12.8 Å (pore II), and 4.8 to 10.4 Å (pore III) by the choice of auxiliary ligands. All members of this series have noninterpenetrating structures and exhibit robust architectures, as evidenced by their permanent porosity and high thermal stability (up to 300 °C). The structural integrity and specific surface areas could be systematically optimized using supercritical CO2 exchange methods for framework activation resulting in BET surface areas ranging from 1250 to 2250 m2/g. Most interestingly, as a structural landmark, we found the pore surfaces lined with charge gradients employed by the pyridinium ligands. This key feature results in significant adsorption of carbon dioxide and methane which is attributed to polarization effects. With this contribution we pioneer the reticulation of pyridinium building blocks into extended zwitterionic networks in which specific properties can be targeted

The Relationship between Eating Behaviors of Children and Mothers, and Nutritional Status of Children

Introduction: Parents have a significant impact on child nutrition and the child's eating habits in long-term behavior. This study aims to examine the effects of mothers' attitudes on the eating behaviors of children and the determination of their nutritional status.Method: Children's eating habits and mothers' eating attitudes were examined in 417 children with face-to-face interviews using the Child Feeding Questionnaire (CFQ). The participants' anthropometric characteristics were determined, and body mass indexes (kg/m2) were calculated. AnthroPlus software was used to determine the children's BMI-for-age Z-scores. BeBiS nutrition information system was used to assess children's food intake.Results: The mothers' median BMI was above the overweight threshold. The lowest CFQ score was for perceived child weight, and the maximum score was for food restriction. Significant differences were found in mothers ages, mothers' BMIs, children's WAZ and BAZ scores, and BMIs, weight (p<0.001), perceived parent weight scores (p=0.04), and pressure to eat (p=0.04). Families should be conscious about nutrition for the protection and promotion of children's health

Gelişmekte Olan Doğu Avrupa Ülkelerinde Kredi Genişlemesi ve Borçlanmanın Ekonomik Büyüme Üzerine Etkileri: Panel Veri Analizi

Bu çalışmada gelişmekte olan Doğu Avrupa ülkelerinden satın alma yöneticileri endeksine (PMI) göre son 3 yılda (2015-2018) en başarılı performansı sergileyen altı Doğu Avrupa ülkesinin (Çekya, Macaristan, Polonya, Rusya Federasyonu, Yunanistan ve Türkiye) Gayrisafi Yurtiçi Hasıla (GSYIH) büyüme oranına etki eden ekonomik ve finansal faktörler incelenmiştir. 2002 ve 2018 yıllarını kapsayan 16 yıllık dönemde, Kredi Genişlemesi ve Borç Servis Oranının GSYIH büyüme oranı üzerindeki etkisi Panel Rassal Etkiler Regresyon Modeli ile tahmin edilmiştir. Konuyla ilgili yapılan çalışmaların önemli bir bölümünde elde edilen bulgular kredi genişlemesi ve GSYIH büyüme oranı arasındaki pozitif ilişkiyi doğrulamaktadır. Ancak borç servis servis oranı ve GSYIH büyüme oranı arasındaki ilişkiyi inceleyen çalışmalarda farklı bulgulara ulaşıldığı görülmektedir.    Analiz döneminde gelişmekte olan Doğu Avrupa ülkelerinde borç servis oranındaki artışın ve Kredi Genişlemesinin GSYIH büyüme oranı üzerinde istatistiki olarak anlamlı pozitif etki yarattığı gözlemlenmiştir

Forecasting Gold Prices Time Series by Using Joint Analysis and Separately Analysis

In recent years, there are many studies rely on forecasting with artificial neural networks. In this study, artificial neural networks are discussed considerably in demand over the past decade in the world finance literature. In the study, forecasting for the highest and the lowest gold prices with feed forward artificial neural networks are comprehensively studied. Linear or curvilinear functions are used in activation functions of artificial neural networks. Model1 and Model2 are used. Model1 has linear activation function in output layer and Model2 has lojistic activation function in output layer. Initially, we used two separate feed-forward artificial neural networks for analyzing the lowest and the highest gold prices values. Afterwards, lagged variables of time series are jo?ntly given to artificial neural networks as input. We jointly forecast the lowest and the highest gold prices. Artificial neural networks gave better results for certain architectures. The forecasting results are discussed according to Root Mean Square Error (RMSE), Mean Absolute Percentage Error (MAPE), Mean Absolute Deviation (MAD) and Direction Accuracy (DA) criterion. Jointly analysis gave better results

Microwave assisted synthesize of new some benzimidazole derivatives and determination of protonation constant of these compounds in non-aqueous media

A series of 2-substituted benzimidazole derivatives have been synthesized via microwave mediated process. Different benzimidazole derivatives were titrated with tetrabutylammonium hydroxide in four non-aqueous solvents (isopropyl alcohol, N,N-dimethylformamide,tert-butyl alcohol and acetonitrile), using potentiometric method. The half neutralization potential values and the corresponding pKa values were determined for all cases