Synthesis and Evaluation of Coumarin–Resveratrol Hybrids as 15-Lipoxygenaze Inhibitors

A series of coumarin–resveratrol hybrids, 3-arylcoumarin derivatives 3a–u, were synthesized through the intermolecular condensation reaction of various salicylaldehydes and phenylacetic acids in the presence of 1,4-diazabicyclo[2.2.2]octane under solvent-free conditions. All the synthesized compounds were screened for their inhibitory potency against soybean 15-lipoxygenase. Among them, three compounds (3c, 3j, and 3q) showed good enzyme-inhibitory activities.     

Experimental investigation toward obtaining a new correlation for viscosity of WO3 and Al2O3 nanoparticles-loaded nanofluid within aqueous and non-aqueous basefluids

In this study, the effect of temperature and mass fraction of Al₂O₃ and WO₃ nanoparticles dispersed in deionized water and liquid paraffin was investigated on dynamic viscosity of nanofluid. The results of the TEM tests showed that the size of Al₂O₃ and WO₃ nanoparticles was ranged from 10 to 60 nm, and the results showed that nanoparticles were semi-spherical. Also the results of DLS and zeta potential tests, respectively, exhibited the uniform size and high stability of the nanoparticles in the basefluid environment. The findings showed that adding a certain amount of nanoparticles to water and liquid paraffin increases dynamic viscosity, and in the case of various shear rates, the viscosity is constant for the water-based nanofluids, which indicates the Newtonian behavior of the nanofluid. In addition, for those prepared by liquid paraffin as a basefluid, the viscosity does not remain constant at different shear rates and at low amount of shear rate the viscosity achieves higher value, indicating non-Newtonian behavior of liquid paraffin-based nanofluids. The results showed that by increasing the temperature in liquid paraffin-based nanofluid the uniformity and linearity of the viscosity curve at various shear rates could be observed, which represents an approach for Newtonian behavior of nanofluid at higher temperatures. These results also showed that with increasing the mass fraction of nanoparticles in water and liquid paraffin, the viscosity increases at different shear rates. Finally, the correlation presented in this study shows that for nanofluid viscosity as a function of nanoparticles load and temperature, the deviation of correlated data from experimental values is less than 10%.

     

Naphthalene-ring containing diamine and resulting thermally stable polyamides

A new naphthalene-ring containing diamine, bis-[4-(5-amino-naphthalene-1-yloxy)-phenyl]-methanone was prepared from reaction of 5-amino-1-naphthol with 4,4′-dichlorobenzophenone in the presence of K₂CO₃. A series of novel polyamides were prepared by direct polycondensation of the diamine with various commercially available diacid chlorides including terephthaloyl chloride, isophthaloyl chloride, adipoyl chloride, and sebacoyl chloride. All the synthesized polyamides showed good solubility in amide type solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide and they exhibited inherent viscosities in the range of 0.44-0.52 dL/g. According to the DMTA analysis, the glass transition temperatures of the polyamides were found to be 131-187 °C. Thermogravimetric analysis indicated that the polymers were stable up to 190 °C and the 10% weight loss temperatures were recorded in the range of 350-418 °C in air atmosphere.     

Speciation of butyl and phenyltin compounds using dispersive liquid-liquid microextraction and gas chromatography-flame photometric detection

Dispersive liquid-liquid microextraction and gas chromatography-flame photometric detection (DLLME-GC-FPD) were performed for the speciation of butyl and phenyltin compounds in water samples after derivatization with sodium tetraethylborate (NaBEt4). Some important parameters, such as pH, amount of NaBEt4, derivatization time, kind and volume of extraction and disperser solvents, extraction time and salt effect were investigated and optimized. High enrichment factors (825-1036) and low detection limits (0.2-1 ng L(-1)) were obtained under the optimum conditions. The calibration graphs were linear in the range of 0.5-1000 ng L(-1) (as Sn) for the target analytes. The relative standard deviations (RSDs) for the extraction of 20 ng L(-1) (as Sn) of butyl and phenyltin compounds varied from 2.3 to 5.9% (n=7) and from 4.1 to 8.8% (n=7) with and without using internal standard, respectively. Seawater and river water samples were successfully analyzed using the proposed method and the relative recoveries of the studied compounds in the water samples, at spiking levels of 10.0 and 100 ng L(-1) (as Sn) were obtained to be 82.5-104.7%.     

H<Subscript>6</Subscript>P<Subscript>2</Subscript>W<Subscript>18</Subscript>O<Subscript>62</Subscript>: A green and reusable catalyst for the synthesis of 3,3-diaryloxindole derivatives in water

An efficient and improved procedure for the synthesis of oxindoles derivatives is developed via the electrophilic substitution reaction of indoles with various isatins in the presence of a Wells–Dawson tungsten heteropolyacid in water. Correspondence: Yaghoub Sarrafi, Department of Chemistry, University of Mazandaran, Babolsar, Iran.     

Anchoring H3PW12O40 on aminopropylsilanized spinel‐type cobalt oxide (Co3O4‐SiPrNH2/H3PW12O40): A novel nanohybrid adsorbent for removing cationic organic dye pollutants from aqueous solutions

In this work, phosphotungstic acid (H₃PW₁₂O₄₀; PW₁₂) was chemically anchored on aminopropylsiloxane functionalized spherical Co₃O₄ nanoparticles (Co₃O₄–SiPrNH₂) and the resultant nanocomposite (Co₃O₄–SiPrNH₂/PW₁₂) was fully characterized. The results demonstrated successful anchoring of PW₁₂ on the surface of Co₃O₄–SiPrNH₂nanoparticles. The Co₃O₄–SiPrNH₂/PW₁₂ nanohybrid indicated a specific surface area of 42.14 m² g^?1, which was greater than that of pure PW₁₂ (ca. 5 m² g^?1). The adsorption efficiency of this novel adsorbent nanomaterial was evaluated for removing methylene blue (MB), rhodamine B (RhB) and methyl orange (MO) dyes from aqueous solutions. The hybrid nanomaterial exhibited a high adsorption rate and selective adsorptivity for the cationic MB and RhB dyes compared to those for anionic MO dye. The prepared hybrid nanomaterial removed over 98% of MB within 12 min. The effects of initial pH, contact time, adsorbent dosage, and temperature were investigated on the adsorption process. The adsorption capacity of nanohybrid for cationic MB dye was 38.46 mg g^‐1. Also, adsorption kinetics indicated that the adsorption by Co₃O₄–SiPrNH₂/PW₁₂ was well‐modeled using pseudo‐second‐order kinetic model. Finally, thermodynamic parameters revealed that the adsorption was endothermic and spontaneous. The adsorption rate and ability of the Co₃O₄–SiPrNH₂/PW₁₂ were enhanced as compared with Co₃O₄ and Co₃O₄–SiPrNH₂ samples due to enhanced electrostatic attraction intraction. The nanohybride was easily separated and reused without any change in structure. Thus, it could be a promising green adsorbent for removing organic pollutants in water.     

Optimal admission and pricing control problems in service industries with multiple servers and sideline profit

This paper deals with the problem of selecting profitable customer orders sequentially arriving at a company operating in service industries with multiple servers in which two classes of services are provided. The first class of service is designed to meet the particular needs of customers; and the company (1) makes a decision on whether to accept or to reject the order for this service (admission control) and (2) decides a price of the order and offers it to an arriving customer (pricing control). The second class of service is provided as a sideline, which prevents servers from being idle when the number of customer orders for the first class is less than the number of servers. This yields the sideline profit. A cost is paid to search for customer orders, which is called the search cost. In the context of search cost, the company has an option whether to conduct the search or not. In this paper, we discuss both admission control and pricing control problems within an identical framework as well as examine the structure of the optimal policies to maximize the total expected net profit gained over an infinite planning horizon. We show that when the sideline profit is large, the optimal policies may not be monotone in the number of customer orders in the system. Copyright © 2008 John Wiley & Sons, Ltd.     

Microwave-Induced One - Pot Synthesis of some new Spiro [Indoline-3,2′-Thiazolidine]-2,4′(1H)-Diones and Bis [Spiro [Indoline -3,2′-Thiazolidine]-2,4′(1H)-Diones]

The title compounds have been obtained thermally and under microwave irradiation by condensation of isatin, aromatic amines and mercaptoacetic acid in good to excellent yields without isolating the imine intermediates.