Nanostructured Colloidal Solutions of Malachite Green Formulated: Nonlinear Optical Properties and Simulation

Journal of Fluorescence - Malachite green (MG) is a dye that has been presented to use as photosensitizers for photodynamic therapy (PDT). Nonlinear absorption coefficient (β) and nonlinear...     

Oscillation of solutions of second-order nonlinear differential equations of Euler type

We consider the nonlinear Euler differential equation t²x^″+g(x)=0. Here g(x) satisfies xg(x)>0 for x≠0, but is not assumed to be sublinear or superlinear. We present implicit necessary and sufficient condition for all nontrivial solutions of this system to be oscillatory or nonoscillatory. Also we prove that solutions of this system are all oscillatory or all nonoscillatory and cannot be both. We derive explicit conditions and improve the results presented in the previous literature. We extend our results to the extended equation t²x^″+a(t)g(x)=0.     

The electrocatalytic examination of cephalosporins at carbon paste electrode modified with CoSalophen

The electrocatalytic oxidation of cephalexin and cefazolin has been studied at a carbon paste electrode modified with cobalt salophen (CoSal) by cyclic voltammetry. The selectivity of the carbon paste modified with CoSal in detecting cephalexin and cefazolin was examined. To suggest the electrocatalytic mechanism for electro-oxidation of cefazolin, the electrochemical behavior of ceftriaxone was investigated which has a thiol group out of the beta lactam ring. The electrocatalytic oxidation of these antibiotics is shown to be irreversible at the CoSal modified electrode. Scan rate dependence of cefazolin, which is a sulfur-containing compound, has been examined. The results indicated that the electrocatalytic oxidation of the compounds is diffusion controlled. The responses of the modified electrode were compared with those of unmodified electrode and it has shown that the modified electrode has better sensitivity than unmodified electrode to the detection of cefazolin. The overall number of electrons contributed to the oxidation of cefazolin is obtained 1 by chronoamperometry; the number of electron involved in the rate-determining step was 1. The results of differential pulse voltammetry (DPV) using the modified electrode with high sensitivity were applied for the determination of cefazolin in human synthetic serum samples. The linear range was obtained from 1 × 10⁻⁵ to 1 × 10⁻³ M for DPV determination of cefazolin in buffered solutions (pH 3.0).     

Singular solutions of elliptic equations on a perturbed cone

In this work we obtain positive singular solutions of

$\{\begin{array}{ccc}?\mathrm{\Delta }u(y)\hfill & \hfill =\hfill & u{(y)}^p\text{ in }y\in {\mathrm{\Omega }}_t,\hfill \\ u\hfill & \hfill =\hfill & 0\text{ on }y\in ?{\mathrm{\Omega }}_t,\hfill \end{array}$

where ${\mathrm{\Omega }}_t$ is a sufficiently small $C^{2,\alpha }$ perturbation of the cone $\mathrm{\Omega }:=\{x\in {\mathbb{R}}^N:x=r\theta ,r>0,\theta \in S\}$ where $S?S^{N?1}$ has a smooth nonempty boundary and where $p>1$ satisfies suitable conditions. By singular solution we mean the solution is singular at the ‘vertex of the perturbed cone’. We also consider some other perturbations of the equation on the unperturbed cone Ω and here we use a different class of function spaces.     

High Stability of a Phosphenium Ion Allows Umpolung of P--H Bonds

The high intrinsic stability of 1,3,2-diazaphospholenium cations enhances ionic polarization of covalent P--X bonds in P -halogeno- and P -hydrido-diazaphospholenes. The physical properties of the latter suggest a hydridic nature of the P--H bond, and their reactivities display an "Umpolung" as compared to known reaction patterns of phosphines.     

Light-induced dehydrogenation of 3,4-dihydropyrimidin-2(1H)-ones

Abstract  

UV light irradiation of Biginelli 3,4-dihydropyrimidin-2(1H)-ones in chloroform in an argon atmosphere leads to dehydrogenation of these compounds to their corresponding pyrimidin-2(1H)-ones in excellent yields. Irradiation in the same solvent under an oxygen atmosphere generates, in addition, various hitherto unidentified products. A light-induced electron transfer from the substrate to the solvent is proposed as the initial event, supported by the detection of dichloromethane and hydrogen chloride in the photolysate.     

(Liquid + liquid) equilibria in ternary aqueous mixtures of phosphoric acid with organic solvents at T = 298.2 K

(Liquid + liquid) equilibrium (LLE) data for the ternary mixtures of {water (1) + phosphoric acid (2) + organic solvents (3)} were determined at T = 298.2 K and atmospheric pressure. The organic solvents were cyclohexane, 2-methyl-2-butanol (tert-amyl alcohol), and isobutyl acetate. All the investigated systems exhibit Type-1 behaviour of LLE. The immiscibility region was found to be larger for the (water + phosphoric acid + cyclohexane) ternary system. The experimental LLE results were correlated with the NRTL model, and the binary interaction parameters were obtained. The reliability of the experimental tie-line results was tested through the Othmer–Tobias and Bachman correlation equations. Distribution coefficients and separation factors were evaluated over the immiscibility regions and a comparison of the extracting capabilities of the solvents was made with respect to these factors. The experimental results indicate the superiority of cyclohexane as the preferred solvent for the extraction of phosphoric acid from its aqueous solutions.     

Application of fuzzy topsis for ranking suppliers of supply chain in automobile manufacturing companies in Iran

Evaluating, ranking and selecting of good supplier play an important role in decreasing of buying risk and increasing of efficiency and effectiveness in value chain and competitive ability of organizations. The goal of this paper is determination and localization of criteria, ranking and selecting suppliers in Automobile Manufacturing Companies in Iran. Based on literature review, 27 criteria were selected and localized, then using factor analysis, they were decreased to 6 items including quality, delivery, technical skill, after sales services, investment and product design. Ultimately, 4 suppliers including Tavan, Borna, Saba and Niroogostaran have been assessed and ranked by fuzzy topsis technique. The results of the research state that score of Borna is better than others with coefficient of 0.52, and from this view, Tavan, Saba and Niroogostaran are in the next ranking with coefficient of 0.45, 0.41, 0.31, respectively. Finally, it concludes some remarks including discussion, summary of implications for managers about how they can use this research results for selecting the best supplier and promoting the competitive ability of their organization, and directions for their further work too.