On finite completely simple semigroups having no finite basis of identities

The purpose of this note is to provide a correct proof of the fact that there exist finite completely simple semigroups having no finite basis of identities.     

New synthesis of ( E )-3,7-dimethyl-2,7-octadienylpropionate and ( E )-3,7-dimethyl-2-octen-1,8-diol, pheromone components of San Jose scaleinsect Quadraspidiotus pernicious and african monarch butterfly Danaus chrysippus

6-Methyl-6-hepten-2-one (3) on reaction with ethyl α-dimethylphosphonate/NaH gives a mixture of (E)-and (Z)-conjugated esters. The major (E)-isomer, (E)-ethyl-3,7-dimethyl-2,7-octadienoate (4), on reduction with LiAlH₄ at room temperature furnishes (E)-3,7-dimethyl-2,7-octadien-l-ol (5) which on propionylation affords (E)-3,7-dimethyl-2,7-octadienyl propionate (1). Carbinol (5) is converted into its silyl ether (E)-2,6-dimethyl-8-t-butyldimethylsilyloxy-l,6-octadiene (6) witht-Bu(Me)₂SiCl in CH₂Cl₂, which on hydroboronation-oxidation with 9-BBN/NaOH-H₂O₂ followed by disilylalion with (n-Bu)₄N⁺ F⁻ at room temperature, gives (E)-3,7-dimethyl-2-octen-l,8-diol (2).     

Efficient Role of Ionic Liquid (bmim)HSO4 as Novel Catalyst for Monotetrahydropyranylation of Diols and Tetrahydropyranylation of Alcohols

A simple procedure for the monotetrahydropyranylation of diols and alcohols, in excellent to moderate yields, has been reported using a catalytic amount of the acidic ionic liquid, 1‐butyl‐3‐methylimidazolium hydrogensulphate (bmim)HSO₄ under microwave and ultrasonic irradiation. Results have been compared with those obtained by reactions in the absence of these energies, and effectiveness of the recycled ionic liquid has also been studied.     

Electronic structures and thermochemical properties of the small silicon-doped boron clusters B(n)Si (n=1-7) and their anions

We perform a systematic investigation on small silicon-doped boron clusters B(n)Si (n=1-7) in both neutral and anionic states using density functional (DFT) and coupled-cluster (CCSD(T)) theories. The global minima of these B(n)Si(0/-) clusters are characterized together with their growth mechanisms. The planar structures are dominant for small B(n)Si clusters with n≤5. The B(6)Si molecule represents a geometrical transition with a quasi-planar geometry, and the first 3D global minimum is found for the B(7)Si cluster. The small neutral B(n)Si clusters can be formed by substituting the single boron atom of B(n+1) by silicon. The Si atom prefers the external position of the skeleton and tends to form bonds with its two neighboring B atoms. The larger B(7)Si cluster is constructed by doping Si-atoms on the symmetry axis of the B(n) host, which leads to the bonding of the silicon to the ring boron atoms through a number of hyper-coordination. Calculations of the thermochemical properties of B(n)Si(0/-) clusters, such as binding energies (BE), heats of formation at 0 K (ΔH(f)(0)) and 298 K (ΔH(f)([298])), adiabatic (ADE) and vertical (VDE) detachment energies, and dissociation energies (D(e)), are performed using the high accuracy G4 and complete basis-set extrapolation (CCSD(T)/CBS) approaches. The differences of heats of formation (at 0 K) between the G4 and CBS approaches for the B(n)Si clusters vary in the range of 0.0-4.6 kcal mol(-1). The largest difference between two approaches for ADE values is 0.15 eV. Our theoretical predictions also indicate that the species B(2)Si, B(4)Si, B(3)Si(-) and B(7)Si(-) are systems with enhanced stability, exhibiting each a double (σ and π) aromaticity. B(5)Si(-) and B(6)Si are doubly antiaromatic (σ and π) with lower stability.     

Sources of Environmental Pollution in Ankara (Turkey): Geochemistry and Traffic Effects—PEDXRF Applications

Road dusts were collected from the main streets in the vicinity of Ankara, the capital city of Turkey, including exhaust dust samples from the different fuel-based motor vehicles and sample pieces of brake pads to characterize their metal compositions by polarized energy-dispersive X-ray fluorescence (PEDXRF) spectrometry. Road dust samples were gathered by a vacuum dust sweeper from nine different densely populated residential settlement regions of Ankara, far from large industrial plants. Heavy metal contents of the road dusts were analyzed during the summertime to determine the metal pollution due to the motor vehicle exhaust, abrasion of brake pads, and lithology, ignoring the industrial and heating sources of pollution. The results of the analysis showed that the elements of Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Sn, Pb, and Th in road dust samples were not derived from the lithology and industrial plants but from the motor fuel exhausts and brake pad abrasion. Generally, urban environmental pollution due to the toxic trace metals from traffic is harmful for the human health as well as the ecosystems near Ankara.     

Analysis of tincal ore waste by energy dispersive X-ray fluorescence (EDXRF) Technique

Etibank Borax Plant is located in K?rka-Eski?ehir, Turkey. The borax waste from this plant was analyzed by means of energy dispersive X-ray fluorescence (EDXRF). The standard addition method was used for the determination of the concentration of Al, Fe, Zn, Sn, and Ba. The results are presented and discussed in this paper.     

Computational Investigation of the Substituent Effect on the Intramolecular Proton Transfer Reaction of 3-Hydroxytropolone

The effects of substituent type and position on the proton transfer reaction of 3-hydroxytropolone(3-OHTRN) have been investigated theoretically by using density functional theory at the level of B3LYP/ 6-31+G** method. The influence of solvent on the proton transfer reactions of substituted 3-OHTRN has been examined using the self-consistent isodensity polarized continuum model(SCI-PCM) in water. As a result, while the proton transfer reaction is kinetically the easiest by substitution on position 3 of-NH2 group in the gas phase, it is kinetically the easiest by substitution on position 5 of the same group in water. In addition, these reactions are either kinetically or thermodynamically easier in the gas phase than that in water, except the reaction of structure with-NH2 group at position 6.     

Efficient synthesis of (+/-)-7-isopropyl-2,10-dimethyl-8(E),10-undecadien-4-one and 3,7-dimethyl-11-oxo-2(E),6(E)-dodecadienol (oxocrinol) under ultrasound

A simple and convergent synthesis of the title compounds has been achieved involving Zn-Cu couple catalysed conjugate addition of allylic halides to alpha,beta-unsaturated carbonyl compounds promoted by ultrasonic waves in aqueous medium as a key step in good overall yields.