Convenient Synthesis of 3,5‐Disubstituted Isoxazoles

α,β‐Unsaturated oximes obtained from the corresponding α,β‐unsaturated ketones on treatment with 2 equivalents of manganese dioxide in refluxing chloroform gives 3,5‐disubstituted isoxazoles in good yields.     

Voltammetry in Room Temperature Ionic Liquids: Comparisons and Contrasts with Conventional Electrochemical Solvents.

The recent literature is surveyed to explore the nature of voltammetry in room temperature ionic liquids. The extent of similarities with conventional electrochemical solvents is reported and some surprising differences are noted.     

Assessing ion-exchange properties and purity of lipophilic electrolytes by potentiometry and spectrophotometry

Many ionic salts synthesized using metathesis are often found to contain significant amounts of impurities, despite careful control of the weighing of starting materials. In this work, a potentiometric method is devised to monitor ion-exchange properties (or ‘purity’) of an organic solvent containing a lipophilic electrolyte. Its permselective behaviour is monitored by treating the solvent as a liquid membrane and contacting it with two aqueous solutions with different electrolyte activities. This electrolyte mismatch results in a drastic potential change when excess lipophilic cation-exchanger is titrated with anion-exchanger, altering the membrane from being cation to anion responsive. Here, the cation-exchanger potassium tetrakis(4-chlorophenyl)borate (KTpClPB) dissolved in nitrobenzene was titrated with tetradodecylammonium chloride (TDDACl), in contact with Ag/AgCl electrodes placed in aqueous 1 M and 10^?2 M KCl, respectively. The predicted potential change of ?214 mV was observed at the equivalence point, forming the inert lipophilic electrolyte ETH 500, in a very small concentration range of added anion-exchanger (0.8% for ±10 mV), suggesting good precision. The approach was confirmed by monitoring absorbance and fluorescence intensity changes of the chromoionophore Nile Blue. This method may be applied for the synthesis of a range of highly lipophilic salts for which established metathesis protocols are not suitable.     

Synthesis of Bis‐acridine Derivatives Exhibiting Anticancer and Anti‐inflammatory Activity

A series of bis‐acridine derivatives 3a – j and 5a – j have been synthesized by condensation of 9‐chloro‐2,4‐(un)substituted acridines (1a – e) and 9‐isothiocyanato‐2,4‐(un)substituted acridines (4a – e) with diamine 2a and 2b , respectively. These bis‐acridines were evaluated in vitro for activity against a panel of human cancer cell lines of lung (NCI H‐522), ovary (PA1), breast (T47D), colon (HCT‐15), and liver (HepG2). Several bis‐acridines were found to possess good anticancer activity against various cancer cell lines. Of these, compound 3h exhibited good anticancer activity against all cancer cell lines tested except liver (HepG2) cell line. In addition to this, these compounds were screened for anti‐inflammatory activity at a dose of 50 mg/kg p.o. Compound 3g exhibited 41% anti‐inflammatory activity, which is better than most commonly used standard drug ibuprofen, which showed 39% anti‐inflammatory (at 50 mg/kg p. o.) activity.     

Chlorate ion mediated rutile to anatase reverse phase transformation in the TiO2 nanosystem

Rutile TiO(2) nanoneedles (8 nm × 100 nm) synthesized at room temperature by anodization in perchloric acid (pH < 1) are shown to undergo an interesting reverse phase transformation to anatase nanoparticles (8 nm) at 300 °C only if the chlorate ions are maintained in the ambient medium. When chlorate ions are removed by multiple washing, the rutile phase and the needle morphology are maintained. The mechanism of formation of the ion-stabilized solid and its thermal evolution is discussed.     

Synthesis,anti‐inflammatory,and anticancer activity evaluation of some heterocyclic amidine and bis‐amidine derivatives

Heterocyclic amidine derivatives of benzothiazole ( 6a , 6b , 6c ), benzimidazole ( 6d , 6e , 6f ), benzoxazole ( 6g , 6h , 6i ), and bis‐amidine derivatives of pyrimidine, ( 7a , 7b ) & triazole ( 7c , 7d , 7e ) ring system have been synthesized by nucleophilic addition reaction. All these compounds were screened for anti‐inflammatory and anticancer activities. At a dose of 50 mg/kg p.o., compounds 6c (39%), 6e (39%), and 6f (39%) exhibited anti‐inflammatory activity comparable to standard drug ibuprofen, which showed 39% activity and compounds 6b , 6e , 7a , and 7c exhibited moderate anticancer activity against cervix (HELA); neuroblastoma (IMR‐32); breast (MCF‐7), leukemia (THP‐1); and cervix (HELA) human cancer cell lines, respectively. J. Heterocyclic Chem., (2011).     

Rapid upregulation of cytoprotective nitric oxide in breast tumor cells subjected to a photodynamic therapy-like oxidative challenge

Many tumor cells produce nitric oxide (NO) as an antiapoptotic/progrowth molecule which also promotes antiogenesis and tumor expansion. This study was designed to examine possible antagonistic effects of endogenous NO on tumor eradication by photodynamic therapy (PDT). Using COH-BR1 breast cancer cells sensitized in mitochondria with 5-aminolevulinic acid (ALA)-generated protoporphyrin IX as a model for ALA-based PDT, we found that caspase-9 activation and apoptotic death following irradiation were strongly enhanced by 1400W, an inhibitor of inducible nitric oxide synthase (iNOS). RT-PCR and Western analyses revealed a substantial upregulation of both iNOS mRNA and protein, beginning ca 4 h after irradiation and persisting for at least 20 h. Accompanying this was a strong 1400W-inhibitable increase in intracellular NO, as detected with the NO probe, DAF-2-DA. Short hairpin RNA-based iNOS knockdown in COH-BR1 cells dramatically reduced NO production under photostress while enhancing caspase-9 activation and apoptosis. These findings suggest that cytoprotective iNOS/NO induction in PDT-treated tumor cells could reduce treatment efficacy, and point to pharmacologic intervention with iNOS inhibitors for counteracting this.     

Fast iterative solvers for buoyancy driven flow problems

We outline a new class of robust and efficient methods for solving the Navier–Stokes equations with a Boussinesq model for buoyancy driven flow. We describe a general solution strategy that has two basic building blocks: an implicit time integrator using a stabilized trapezoid rule with an explicit Adams–Bashforth method for error control, and a robust Krylov subspace solver for the spatially discretized system. We present numerical experiments illustrating the efficiency of the chosen preconditioning schemes with respect to the discretization parameters.     

Vertex colorings of graphs without short odd cycles

Motivated by the work of Ne?et?il and Rödl on “Partitions of vertices” we are interested in obtaining some quantitative extensions of their result. In particular, given a natural number r and a graph G of order m with odd girth g, we show the existence of a graph H with odd girth at least g and order that is polynomial in m such that every r‐coloring of the vertices of H yields a monochromatic and induced copy of G. © 2010 Wiley Periodicals, Inc. J Graph Theory 68: 255‐264, 2011