Highly Chemoselective Thiocarbonyl Oxidation upon Reaction of 4-Methyl-3-phenyl-2-thiazolidinethione with Singlet Oxygen

4-Methyl-3-phenyl-2-thiazolidinethione was reacted with both photochemically and chemically generated singlet oxygen. Despite reaction conditions which were selected to favor oxidation of the sulfide group, both reactions afforded a single product arising solely from thiocarbonyl oxidation.     

Neue Thiosubstituierte Butadien- Und Butenin Verbindungen Aus Hexachlorbutenen Und Thiolen

2,3-Di-H-butene compound 1 gave compounds 3a-f , 4a , 4e , and 5a-d in the presence of thiols 2a-f and Et 3 N (or NaOH). Compound 7e was obtained from the reaction of 1,3-Di-H-butene 6 with naphthylthiol in DMF. In the presence of NaOH, compound 6 and 2 mmol of thiol 2g in EtOH gave compounds 8 , 9 , 10 , and 11 .     

Credit risk estimation using payment history data: a comparative study of Turkish retail stores

Our paper presents a comparative study applying logistic regression and multiple criteria decision analysis tools to the operations of wholesalers to assess the credit risk of their retailers using payment history data and to cluster the risky customers by ranking their risk levels. Our sample comprises approximately 6,000 retailer customers and 600.000 transactions of one of the major wholesalers of Turkey. Our findings emphasize the importance of using payment history and some non-financial factors data for predicting the creditworthiness of a firm.     

Synthesis and characterization of physical crosslinking systems based on cyclodextrin inclusion/host‐guest complexation

New supramolecular assemblies based on cyclodextrin and adamantane were prepared. Two methacrylate monomers bearing cyclodextrin and adamantane were synthesized, and copolymerized with poly(ethylene glycol) methyl ether methacrylate, (PEGMA, 300 g/mol), by free radical polymerization. Copolymers bearing pendent cyclodextrin and adamantane were characterized by NMR, FTIR, TGA, SEC, Differential scanning calorimetry (DSC), and UV‐visible spectrophotometer. All copolymers showed two distinct glass transitions. The specific interaction between pendent adamantyl and cyclodextrin was examined by ¹H‐NMR. The viscoelastic properties of supramolecular assemblies were investigated with frequency and temperature sweep experiments. The specific host‐guest interaction between pendent adamantyl and cyclodextrin lead to large increases of the viscosity; and depending on the concentration of these groups, also to gel formation. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 581–592, 2010     

A study of mechanism of nickel interferences in hydride generation atomic absorption spectrometric determination of arsenic and antimony

Studies have been carried out to clarify the mechanism of nickel interferences in the hydride generation atomic absorption spectrometric determination of arsenic and antimony. The most serious nickel interferences are observed when nickel/nickel boride nanoparticles are produced during NaBH₄ reduction. In this study these particles have been observed to have diameters of less than 40 nm and sorb As(III), As(V) and Sb(III) species rather than arsine and stibine generated as so far assumed. Bulk chemical composition and surface structure of these nanoparticles were studied and it was found that if the NaBH₄ reduction is carried out while passing nitrogen through the solution the black nanoparticles were composed of Ni₂B and, if the reduction is carried out under air the black nanoparticles were found to consist of Ni₃B or possibly a mixture of Ni(0) and Ni₂B. Surface analysis studies with scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray photoelectron spectrometry and X-ray diffraction analysis have shown that the particles have amorphous structure consisting of Ni(0), Ni₂B, Ni₃B and Ni(OH)₂. However, sorption studies have shown that Ni(0) and Ni(OH)₂ do not sorb the analyte ions and arsine and stibine significantly.     

Extraction of aqueous of malic acid by trioctylamine extractant in various diluents

In this study malic acid were extracted from aqueous solution by different solvents with and without trioctylamine (TOA). The TOA was dissolved in five different esters (dimethyl phthalate, dimethyl adipate, dimethyl succinate, dimethyl glutarate, and diethyl carbonate), five different alcohols (isoamyl alcohol, hexan-1-ol, octan-1-ol, nonan-1-ol, and decan-1-ol) and two different ketones (diisobutyl ketone (DIBK) and methyl isobutyl ketone (MIBK)). The results are reported as distribution coefficients (K_D), loading factors (T_T), stoichiometric loading factor (T_S), separation factor (S_f) and extraction efficiency (E). The most effective solvent was determined as isoamyl alcohol with a distribution value coefficient of 17.811. The maximum values of equilibrium complexation constants in isoamyl alcohol for (acid:amine) (1:1) K₁₁ and (2:1) K₂₁ were 9.9 and 225.6, respectively. A linear solvation energy relationship (LSER) was accurately regressed to the experimental distribution coefficients.     

Vibration analysis of a rotating tapered Timoshenko beam using DTM

In this study, free vibration analysis of a rotating, tapered Timoshenko beam that undergoes flapwise bending vibration is performed. Derivation of the equations of motion of a rotating, uniform Timoshenko beam was made step by step in a previous work of the authors. Therefore, differential equations of motion are given directly without making any derivations in this paper. The parameters for the hub radius, rotational speed, taper ratio, rotary inertia, shear deformation and slenderness ratio are incorporated into the equations of motion. In the solution part, an efficient mathematical technique called the Differential Transform Method, DTM, is used. Finally, using the computer package Mathematica, the natural frequencies are calculated and the effects of the incorporated parameters are examined. Moreover, numerical examples are solved to make comparisons with the existing results in open literature and it is observed that the agreement between the results is very good.     

QCD phase transition with strange quark in wilson formalism for fermions

The nature of QCD phase transition is studied with massless up and down quarks and a light strange quark, using the Wilson formalism for quarks on a lattice with the temporal direction extensionN _t=4. We find that the phase transition is of first order for the physical strange quark mass.     

Conformational polymorphism in a chiral spiro-cis-ansa-bridged cyclo­triphosphazene derivative

The reaction of spermidine with 2,2,4,4-tetra­chloro-6,6-di­phenyl­cyclo­triphosphazene produces a mixture of products of which one of the fractions is a spiro-cis-ansa deriv­ative, namely 12-chloro-14,14-di­phenyl-2,6,11,13,15,16-hexa­aza-1,12-di­phosphatri­cyclo­[10.3.1.0^1,6]­hexadeca-12,14-diene, C₁₉H₂₆Cl­N₆P₃. Recrystallization of this fraction from different solvents results in the formation of two different crystalline forms. The rod morphology formed in di­chloro­methane–n-hexane (1:1) produces a triclinic structure with three mol­ecules in the asymmetric unit. These three mol­ecules adopt different conformations as a result of two NH groups flipping in an ansa-bridged ring system. The plate morphology crystals, grown in di­chloro­methane–n-hexane–ethyl acetate (1:1:1), produce a C-centred monoclinic structure that adopts a conformation that is essentially the same as one of the forms in the triclinic structure.