Conductivity and band gap of oligo-2-[(4-fluorophenyl) imino methylene] phenol and some of its oligomer-metal complexes

Schiff base oligomer of 2-[(4-fluorophenyl) imino methylene] phenol (FPIMP) was synthesized via oxidative polycondensation reaction in an alkaline medium. Oligomer-metal complex compounds were synthesized from the reactions of oligo-2-[(4-fluorophenyl) imino methylene] phenol (OFPIMP) with Co⁺², Ni⁺² and Cu⁺² ions. The synthesis was achieved by oxidative coupling based on air oxygen as an oxidant. While synthesized Schiff base oligomer was soluble in most common organic solvents, its metal complexes were only soluble in dimethylsulfoxide. Electrochemical HOMO and LUMO band gap (E_g) of monomer, oligomer and its metal complexes were calculated from oxidation and reduction onset values. According to cyclic voltammetry (CV) and UV-vis measurements, electrochemical energy gaps and optical band gap (E_g) values of monomer and oligomer were found to be 3.26 and 3.10; 3.15 and 2.96 eV, respectively. Conductivity measurements of doped and undoped Schiff base oligomer and its metal complexes were carried out by electrometer at a room temperature and atmospheric pressure and were calculated from four-point probe technique. When iodine was used as doping agent, conductivity of this oligomer and its metal complexes were observed to be increased.     

A parametric study for thick plates resting on elastic foundation with variable soil depth

The soil depth is generally considered to be constant for the analysis of plates resting on elastic foundation in the literature. However, it is most reasonable to have a variable subsoil depth as the plate dimensions get larger. In present study, linearly varying subsoil depth is considered as well as constant, linear and quadratic variation of modulus of elasticity with subsoil depth. Also, a parametric study is performed to demonstrate the behavior of thick plates on elastic foundations with variable soil depth. Modified Vlasov Model is used for the analysis of the plate foundation system, and 8-noded Mindlin plate element incorporating shear strain throughout plate thickness is used for the finite element model. Numerical examples are obtained from the literature to compare results and to show the influence of variable soil stratum depth on the behavior of plates. Displacements, bending moments, and shear forces are presented in tabular and graphical formats. As far as results are compared, it can be concluded that variable soil depth significantly affects the variation of the displacements and therefore the internal forces of the plate while keeping it constant ends up with unrealistic results.     

Hot-air drying of purslane (Portulaca oleracea L.)

Drying characteristics of purslane was experimentally studied in a cabinet dryer. The experimental drying data were fitted best to Modified Henderson and Pabis and Midilli et al. models apart from other models to predict the drying kinetics. The effective moisture diffusivity varied from 1.12 × 10^?9 to 3.60 × 10^?9 m²/s over the temperature range studied and activation energy was 53.65 kJ/mol.     

Quantum Chemical,Spectroscopic, and X-Ray Diffraction Studies of N-diphenylphosphino-4-methylpiperidine Selenide (1)

The title molecule, N-diphenylphosphino-4-methylpiperidine selenide(1), was prepared and characterized by elemental analysis, ¹H-NMR, ³¹P-{¹H} NMR, IR, and X-ray single-crystal determination. The compound crystallizes in the monoclinic space group P 2₁/c. In addition to the molecular geometry from X-ray determination, vibrational frequencies and gauge, including atomic orbital (GIAO) ¹H- and ³¹P-{¹H} NMR chemical shift values of the title compound (1) in the ground state, were calculated using the Hartree–Fock and density functional methods with the 6-31G(d, p) basis set. The calculated results show that the optimized geometries can well reproduce the crystal structures. Besides, the theoretical vibrational frequencies and chemical shift values show good agreement with experimental values. The predicted nonlinear optical (NLO) properties of the title compound are greater than those of urea. In addition, density functional theory (DFT) calculations of the molecular electrostatic potentials (MEPs), frontier molecular orbitals (FMOs) of the title compound were carried out at the B3LYP/6-31G(d) level of theory.     

Radiostability of Allantoin by Using Electron Spin Resonance Spectroscopy

The radiosterilization potential and dosimetric feature of allantoin were investigated through the molecular degradations produced after ultraviolet and gamma irradiation using electron spin resonance, infrared, and ultraviolet spectroscopies and thermal measurement techniques (differential thermal analysis and the glass transition temperature). Although ultraviolet-irradiated allantoin presents no electron spin resonance signal, gamma irradiation exhibited an electron spin resonance signal of triplet appearance. Room temperature and high-temperature line intensity and spectrum area data and their variations with applied microwave power, storage time, annealing time, annealing temperature, and applied radiation dose were analyzed by assuming the production of two different types of radicals having different spectroscopic and decay characteristics. Based on its relatively stable nature toward gamma and ultraviolet radiations, it was concluded that allantoin itself and the products containing it can be sterilized by gamma and/or ultraviolet radiations without creating a great loss in its beneficial effects in the allowed radiosterilization dose limits.     

Cytotoxic effect,enzyme inhibition,and in silico studies of some novel N-substituted sulfonyl amides incorporating 1,3,4-oxadiazol structural motif

Molecular Diversity - The acetylcholinesterase and carbonic anhydrase inhibitors (AChEIs and hCAIs) remain key therapeutic agents for many bioactivities such as anti-Alzheimer and antiobesity...     

Some Tauberian conditions for Cesàro summability method

Let u = (u _n ) be a sequence of real numbers whose generator sequence is Cesàro summable to a finite number. We prove that (u _n ) is slowly oscillating if the sequence of Cesàro means of (ω _n ^(m−1)(u)) is increasing and the following two conditions are hold:

The inverse of nonsymmetric two-level Toeplitz operator matrices

The Gohberg–Semencul formula allows one to express the entries of the inverse of a Toeplitz matrix using only a few entries (the first row and the first column) of the inverse matrix, under some nonsingularity condition. In this paper we will provide a two variable generalization of the Gohberg–Semencul formula in the case of a nonsymmetric two-level Toeplitz matrix with a symbol of the form $f(z_1\text{,}{z}_2)=\frac{1}{\overline{P(z_1\text{,}{z}_2)}Q(z_1\text{,}{z}_2)}$ where $P(z_1\text{,}{z}_2)$ and $Q(z_1\text{,}{z}_2)$ are stable polynomials of two variables. We also consider the case of operator valued two-level Toeplitz matrices. In addition, we propose an equation solver involving two-level Toeplitz matrices. Numerical results are included.     

Heat capacities and thermodynamic functions of CdNb2O6 and CdTa2O6

Journal of Thermal Analysis and Calorimetry - The molar heat capacity parameters of CdNb2O6 and CdTa2O6 oxides, which attracted attention for their promising catalytic and optical properties, were...     

Characterization of the Chemical Profile of Euphorbia Species from Turkey by Gas Chromatography–Mass Spectrometry (GC-MS), Liquid Chromatography–Tandem Mass Spectrometry (LC-MS/MS), and Liquid Chromatography–Ion Trap–Time-of-Flight–Mass Spectrometry (LC-IT-TOF-MS) and Chemometric Analysis†

The Euphorbiaceae family comprises of about 300 genera and 5000 species primarily distributed in America and tropical Africa. The Euphorbia genus is represented by 105 species and locally named as “Sütle?en” and “Xa?îl” in Turkey. The present study aimed to determine the chemical constituents of E. aleppica, E. eriophora, E. macroclada, E. grisophylla, E. seguieriana subsp. seguieriana, E. craspedia, E. denticulata, E. falcata, and E. fistulosa, and classify them by utilizing the chemometric techniques of principal component analysis (PCA) and hierarchical cluster analysis (HCA). Linoleic acid, 17-tetratriacontane, palmitic acid, and hexatriacontane were the major fatty acids from the gas chromatography–mass spectrometry (GC/MS) analyses. Characterization of 268 constituents of the studied species was achieved by liquid chromatography–ion trap–time-of-flight–mass spectrometry (LC-IT-TOF-MS). Furthermore, a new liquid chromatography–tandem mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous quantitative determination of 11 compounds (quinic acid, protocatechuic acid, rutin, hesperidin, eugenol, p-coumaric acid, piceatannol, scopoletin, dl-kavain, chrysophanic acid, and resiniferatoxin) in these species. The developed method was validated for the linearity, limit of detection, limit of quantification, repeatability, and recovery.