Assignment of the First Photoelectron Band of CH3CHBr(X2A) Using Ab-initio and Density Functional Theory (DFT) Computational Calculations

HeI photoelectron spectra have been recorded for the reaction of atomic fluorine with ethyl bromide at different reaction times. A structured band associated with a short-lived primary reaction product has been recorded at a mixing distance of 12 mm above the photon beam. The adiabatic and vertical ionization energies of this band was measured as 7.78 ± 0.01 and 8.05 ± 0.01 eV, respectively . The average vibrational separation of 700 ± 30 cm⁻¹ was observed in this band. Vertical ionization energies were computed in this work for CH₃CHBr(X²A) and CH₂CH₂Br(X²A) via ΔSCF, ΔMP2 (full) and Δ(B3LYP) levels of theory using different basis sets. Mulliken population analysis and force constant calculations have also been carried out for CH₃CHBr(X²A) and CH₂CH₂Br(X²A) and their singlet cationic states. Comparison between the experimental vertical ionization energies and the corresponding values computed for CH₃CHBr (X²A) and CH₂CH₂Br(X²A) at different levels of theory led to the assignment of the observed first photoelectron band to the ionization of CH₃CHBr(X²A). The observed vibrational structure was assigned to the excitation of C–Br stretching mode in CH₃CHBr⁺ (X¹A).     

A convenient one-step preparation of diaminonitrile compounds

A new method for preparation of diaminonitrile compounds is reported.In this method primary aliphatic diamine compounds were condensed with two equivalents of benzaldehyde and sodium cyanide in presence of an aqueous solution of sodium hydrogensulfite under mild conditions.This method provides an efficient,convenient and practical method for the syntheses of diaminonitrile compounds and the products are easily isolated.The prepared new compounds were characterized by elemental analysis,IR,NMR spectroscop...     

Tsallis $$\delta $$-entropy in an accelerating BIon

In this research, we consider thermodynamically the behaviour of an accelerating BIon and show that the entropy of this system has the form of Tsallis entropy. A BIon is a system that consists of a brane, an anti-brane and a wormhole which connects them together. By increasing the acceleration of branes, the area of BIon increases and its Tsallis entropy grows.     

Finite Convergence of a Subgradient Projections Method with Expanding Controls

We study finite convergence of the modified cyclic subgradient projections (MCSP) algorithm for the convex feasibility problem (CFP) in the Euclidean space. Expanding control sequences allow the indices of the sets of the CFP to re-appear and be used again by the algorithm within windows of iteration indices whose lengths are not constant but may increase without bound. Motivated by another development in finitely convergent sequential algorithms that has a significant real-world application in the field of radiation therapy treatment planning, we show that the MCSP algorithm retains its finite convergence when used with an expanding control that is repetitive and fulfills an additional condition.     

Comparison of novel pyridine-functionalized mesoporous silicas for Au(III) extraction from natural samples

A technique for solid-phase extraction utilizing pyridine-functionalized nanoporous silica (MCM-41, MCM-48 and SBA-15) was developed for the determination of gold in different samples using flame atomic absorption spectrometry. The effects of concentration and volume of eluent, pH of the solution, flow rate of extraction, sample volume and of potentially interfering ions on the efficiency of preconcentration and recovery was investigated. The limit of detection is lower than 45 pg mL^?1. Under optimal conditions, the accuracy and precision (RSD%) of the method were calculated to be >99.5% and <0.7% for the two MCMs (41 and 48) and >89.5%, and <1.5% for SBA-15, respectively. The SPE technique was used to determine the concentration of gold in natural and industrial wastewater with satisfactory results.

Fixed points of continuous DCPOs

In this article we show that for a continuous DCPO D, the set of fixed points of every self-map is a continuous DCPO if and only if x<y implies x is way below y. We also prove that some classes of continuous functions have the property that if a self-map on a DCPO is in the class then the set of fixed points is a continuous DCPO. We also investigate when the set of fixed points is a retract.     

FeCl_3: Highly Efficient Catalyst for Synthesis of α-Amino Nitriles

α‐Amino nitriles are synthesized by the three‐component coupling reaction of aldehydes, amines and trimethylsilyl cyanide using FeCl₃ as a solid acid catalyst, under solvent‐free conditions in good yields. The catalyst was recovered by simple filtration and was recycled in subsequent reactions.     

A Sensitive Method for the Determination of Methadone in Biological Samples Using Nano-Structured α-Carboxy Polypyrrol as a Sorbent of SPME

Nano-structured α-carboxy polypyrrol (PPy- α-COOH) was used as a coating of solid-phase microextraction (SPME) fiber to increase the extraction efficiency of headspace solid phase microextraction (HS-SPME) of methadone (MDN) in biological samples. The carboxy-endcapped polypyrrole film was prepared via electrochemical deposition on a platinum wire. A nano-fibrous structure of PPy-α-COOH with a diameter of 120 nm was obtained. The porous surface structure of the film, revealed by scanning electron microscopy, provided high surface areas and allowed for high extraction efficiency of methadone. Then the analysis of the extracts was carried out by a gas chromatography-flame ionization detector. In order to achieve maximum extraction efficiency, different parameters affecting the extraction conditions were optimized. Under the optimized conditions, the limit of detections and the limit of quantifications of the method in the range of 0.02–0.035 and 0.06–0.10 μg L⁻¹ were obtained for different matrices. The relative recoveries in different samples were in the range of 95–97%. Finally, the feasibility of the proposed method was successfully confirmed by extraction and determination of MDN in human urine and plasma samples in the range of microgram per liter, and suitable results were obtained (RSDs <5.3%).

     

A Sensitive Method for Determination Glycolic Acid, Mono- and Di-Chloroacetic Acids in Betaine Media Using Amino-Functionalized SBA-15 as a Sorbent and HPLC Assay

In this paper, amino-modified nanoporous silica (APS-SBA-15) was synthesized as a new solid-phase sorbent for the extraction of glycolic acid, monochloroacetic acid, and dichloroacetic acid in synthetical betaine products. Octadecyl silica cartridge was used to reduce the concentration of matrix betaine. PS-Ag⁺ pre-treatment cartridge was applied to remove high Cl^? concentration. The obtained effluent sample was passed through of the APS-SBA-15 sorbent. The effect of pH, flow rate of sample and eluent, and type and volume of the eluent were investigated and optimized. Chloroacetate and glycolate were eluted with 0.8 mol L^?1 solution of HClO₄ and measured by HPLC with a UV–vis detector. At optimum effective parameters, preconcentration factor of 129 was achieved in this method. The detection limits of mono- and dichloroacetic acid and glycolic acid were 13, 3.7, and 8.6 ng L^?1, respectively.