1,314 research outputs found
In therapy with avatars
No full textCombating phobias and psychotic disorders using virtual technology: that is what the work of Dr. Willem-Paul Brinkman of the Faculty of Electrical Engineering, Mathematics and Computer Science involves. Of course one does not have any of these disorders oneself – or at least that’s what our reporter also thought
Antiproliferative Effect Of baylis-hillman Adducts And a new Phthalide Derivative On human Tumor Cell Lines
No full textIn this work we report our results concerning the study on the in vitro antiproliferative activity of 18 Baylis-Hillman adducts and some derivatives against a panel of humor tumor cell lines. A brief qualitative structure-activity relationship study indicated that carbon-carbon double bond and the presence of an electron-withdrawing substituent at the aromatic ring are essential for the activity. A quinoline-phthalide derivative has exhibited a potent effect on the proliferation of all cell lines. It is interesting to note their special cytotoxic activity against NCIADR cell line. © 2006 Elsevier SAS. All rights reserved.416738744Russo, A., DeGraff, W., Friedman, N., Mitchell, J.B., (1986) Cancer Res., 46, pp. 2845-2848Tew, K.D., (1994) Cancer Res., 54, pp. 4313-4320Griffith, O.W., Meister, A., (1979) J. Biol. Chem., 254, pp. 7558-7560Williamson, J.M., Boettcher, B., Meister, A., (1982) Proc. Natl. Acad. Sci. USA, 79, pp. 6246-6249McCarthy, T.J., Hayes, E.P., Schwartz, C.S., Witz, G., (1994) Fundam. Appl. Toxicol., 22, pp. 543-548Coelho, F., Almeida, W.P., Mateus, C.R., Veronese, D., Lopes, E.C.S., Silveira, G.P.S., Rossi, R.C., Pavam, C.H., (2002) Tetrahedron, 58, pp. 7437-7447Mateus, C.R., Almeida, W.P., Feltrin, M.P., Costa, A.M., Coelho, F., (2001) Tetrahedron, 57, pp. 6901-6908Monks, A., Scudiero, D., Skehan, P., Shoemaker, R., Paull, K., Vistica, D., Hose, C., Boyd, M., (1991) J. Natl. Cancer Inst., 83, pp. 757-766Donadel, O.J., Martin, T., Martin, V.S., Villar, J., Padron, J.M., (2005) Bioorg. Med. Chem. Lett., 15, pp. 3536-3539Litchfield, J.T., Wilcoxon, F., (1949) J. Pharmacol. Exp. Ther., 96, pp. 99-14
The Baylis-hillman Reaction With Chiral α-amino Aldehydes Under Racemization-free Conditions
No full textThe Baylis-Hillman reaction with chiral α-amino aldehydes has been revisited. The reaction carried out under the influence of ultrasound avoids the aldehyde racemization almost completely, providing useful chiral substrates which can be used as starting materials for the synthesis of natural products. To demonstrate the synthetic applicability of these adducts, the easy preparation of a bicyclic lactam with an indolizidinic skeleton was accomplished. © Georg Thieme Verlag Stuttgart.3435439Basavaiah, D., Rao, A.J., Satyanarayama, T., (2003) Chem. Rev., 103, p. 811Almeida, W.P., Coelho, F., (2000) Quim. Nova, 23, p. 98(2000) Chem. Abstr., 132, pp. 236562eCiganek, E., (1997) Org. React., 51, p. 201Basavaiah, D., Rao, P.D., Hyma, R.S., (1996) Tetrahedron, 52, p. 8001Santos, L.S., Pavam, C.H., Almeida, W.P., Coelho, F., Eberlin, M.N., (2004) Angew. Chem. Int. Ed., 43, p. 4330Price, K.E., Broadwater, S.J., Walker, B.J., McQuade, D.T., (2005) J. Org. Chem., 70, p. 3980Aggarwal, V.K., Fulford, S.Y., Llyod-Jones, G.C., (2005) Angew. Chem. Int. Ed., 44, p. 1706Mateus, C.R., Coelho, F., (2005) J. Braz. Chem. Soc., 16, pp. 386-396. , http://jbcs.sbq.org.br/online/2005/vol16_n3A/11-238-04.pdfPorto, R.S., Coelho, F., (2004) Synth. Commun., 34, p. 3037Feltrin, M.A., Almeida, W.P., (2003) Synth. Commun., 33, p. 1141Rossi, R.C., Coelho, F., (2002) Tetrahedron Lett., 42, p. 2797Mateus, C.R., Feltrin, M.P., Costa, A.M., Coelho, F., Almeida, W.P., (2001) Tetrahedron, 57, p. 6901Iwabuchi, Y., Furukawa, M., Esumi, T., Hatakeyama, S., (2001) Chem. Commun., p. 2030Iwabuchi, Y., Sugihara, T., Esumi, T., Hatakeyama, S., (2001) Tetrahedron Lett., 42, p. 7867Masunari, A., Trazzi, G., Ishida, E., Coelho, F., Almeida, W.P., (2001) Synth. Commun., 31, p. 2100Roos, G., Manickum, T., (1991) Synth. Commun., 21, p. 2269Drewes, S.E., Khan, A.A., Rowland, K., (1993) Synth. Commun., 23, p. 183Ameer, F., Drewes, S.E., Houston-McMillan, M.S., Kaye, P.T.S., (1986) Afr. J. Chem., 39, p. 57(1986) Chem. Abstr., 105, p. 114809Manickum, T., Roos, G.H.P.S., (1994) Afr. J. Chem., 47, p. 1(1994) Chem. Abstr., 122, p. 159795Alcaide, B., Almendros, P., Aragoncillo, C., (2001) J. Org. Chem., 66, p. 1612Alcaide, B., Almendros, P., Aragoncillo, C., Rodríguez-Acebes, R., (2004) J. Org. Chem., 69, p. 826. , and references cited thereinNayak, S.K., Thijs, L., Zwanenburg, B., (1999) Tetrahedron Lett., 40, p. 981Haner, R., Olano, B., Seebach, D., (1987) Helv. Chim. Acta, 70, p. 1676Almeida, W.P., Coelho, F., (2003) Tetrahedron Lett., 44, p. 937Einhorn, J., Einhorn, C., Luche, J.-L., (1991) Synlett, p. 37Bodanszky, M., Bodanszky, A., (1994) The Practice of Peptide Synthesis, 2nd Ed., , Springer-Verlag: Berlin/HeidelbergYoshifuji, S., Tanaka, K., Kawai, T., Nitta, Y., (1986) Chem. Pharm. Bull., 34, p. 3873Esquerra, J., Pedregal, C., Rubio, A., Yruretagoyena, B., Escribano, A., Sanchez-Ferrando, F., (1993) Tetrahedron, 49, p. 8665Gobiowske, A., Jurczak, J., Jacobsson, U., (1987) Tetrahedron, 43, p. 3063Luly, J.R., Dellaria, J.F., Palttner, J.J., Soderquist, J.L., Yi, N., (1987) J. Org. Chem., 52, p. 1487Fehrentz, J.A., Castro, B., (1983) Synthesis, p. 676Saari, W.S., Fisher, T.E., (1990) Synthesis, p. 453Kemp, D.J., (1986) J. Org. Chem., p. 3921D'Aniello, F., Taddei, M., (1992) J. Org. Chem., 57, p. 5247Romo, D., Meyer, S.D., Johnson, D.D., Schreiber, S.L., (1993) J. Am. Chem. Soc., 115, p. 7906Myers, A.G., Zhong, B.Y., Movassaghi, M., Kung, D.W., Lanman, B.A., Kwon, S., (2000) Tetrahedron Lett., 41, p. 1359. , and references cited thereinSchuch, C.M., Pilli, R.A., (2000) Tetrahedron: Asymmetry, 11, p. 153Dias, L.C., Ferreira, A.A., Diaz, G., (2002) Synlett, p. 1845Dias, L.C., Meira, P.R.R., (2000) Synlett, p. 37Benedetti, F., Miertus, S., Norbedo, S., Tossi, A., Zlatoidzky, P., (1997) J. Org. Chem., 62, p. 9348Vara Prasad, J.V.N., Rich, D.H., (1991) Tetrahedron Lett., 32, p. 5857Cherest, M., Felkin, H., Prudent, N., (1968) Tetrahedron Lett., 18, p. 2199Ahn, N.T., (1980) Top. Curr. Chem., 88, p. 144Hoffmann, R.W., (1989) Chem. Rev., 89, p. 1841Muroni, D., Saba, A., Culeddu, N., (2004) Tetrahedron: Asymmetry, 15, p. 2609Dieter, R.K., Lu, K., (2002) J. Org. Chem., 67, p. 847Sibi, M.P., Christensen, J.W., (1999) J. Org. Chem., 64, p. 6434Lim, S.H., Ma, S., Beak, P., (2001) J. Org. Chem., 66, p. 9056Clive, D.L.J., Yu, M., Li, Z., (2005) Chem. Commun., p. 90
Diastereoselectivity In Heterogeneous Catalytic Hydrogenation Of Baylis-hillman Adducts. Total Synthesis Of (±)-sitophilate
No full textWe describe herein a highly diastereoselective total synthesis of racemic sitophilate, based on the results obtained in a diastereoselective heterogeneous catalytic hydrogenation reaction of a set of Baylis-Hillman adducts originating from aliphatic aldehydes. © 2001 Published by Elsevier Science Ltd.573269016908Baylis, A.B., Hillman, M.E.D., (1972) Chem. Abstr., 77, pp. 34174q. , German Patent 2155113, 1972Basavaiah, D., Rao, P.D., Hyma, R.S., (1996) Tetrahedron, 52, p. 8001Ciganek, E., (1997) Organic Reactions, 51, pp. 201-350. , John Wiley & Sons Inc.: New York, Chapter 2Almeida, W.P., Coelho, F., (2000) Quím. Nova, 23, p. 98. , (Chem. Abstr., 2000, 132, 236562e)Almeida, W.P., Coelho, F., (1998) Tetrahedron Lett., 39, p. 8609Almeida, W.P., Mateus, C.R., Coelho, F., (2000) Tetrahedron Lett., 41, p. 2533Masunari, A., Ishida, E., Trazzi, G., Almeida, W.P., Coelho, F., (2001) Synth. Commun., 31 (14), pp. 2127-2136Faustini, D.L., Giese, W.L., Phillips, J.K., Burkholder, W.E., (1982) J. Chem. Ecol., 8, p. 679Phillips, J.K., Miller, S.P.F., Andersen, J.F., Fales, H.M., Burkholder, W.E., (1987) Tetrahedron Lett., 28, p. 6145Monro, H.A.U., Upitis, E., Bond, E.J., (1972) J. Stored Prod. Res., 8, p. 199Lloyd, C.J., (1973) J. Stored Prod. Res., 9, p. 77Chong, J.M., (1989) Tetrahedron, 45, p. 623Mori, K., Ishikura, M., (1989) Liebigs Ann. Chem., p. 1263Cheskis, B.A., Moiseenkov, A.M., Shpiro, N.A., Stashina, G.A., Zhulin, V.M., (1990) Bull. Acad. Sci. USSR CH, 39, p. 716Cheskis, B.A., Shpiro, N.A., Moiseenkov, A.M., (1991) Bull. Acad. Sci. USSR CH, 40, p. 2205Sugai, T., Sakuma, D., Kobayashi, N., Ohta, H., (1991) Tetrahedron, 47, p. 7237Chu, K.-H., Zhen, W., Zhu, X.-Y., Rosenblum, M., (1992) Tetrahedron Lett., 33, p. 1173Gu, J.X., Zy, L., Lin, G.Q., (1993) Tetrahedron, 49, p. 386Gil, P., González, A., Razkin, J., (1996) Tetrahedron: Asymmetry, 7, p. 3479DiBattista, J.P., Webster, F.X., (1996) Bioorg. Med. Chem., 4, p. 423Gil, P., Razkin, J., González, A., (1998) Synthesis, p. 386Naik, D.G., Puntambekar, H.M., (1998) Synth. Commun., 28 (13), p. 2399Brown, J.M., Cutting, I., (1985) J. Chem. Soc., Chem. Commun., p. 578Brown, J.M., (1987) Angew. Chem., Int. Ed. Engl., 26, p. 190Brown, J.M., Cutting, I., James, A.P., (1988) Bull. Soc. Chim. Fr., p. 211Yamamoto, K., Takagi, M., Tsuji, J., (1988) Bull. Chem. Soc. Jpn., p. 319Brown, J.M., Rose, M., Knight, F.I., Wienand, A., (1995) Recl. Trav. Chim. Pays-Bas, 114, p. 247Brown, J.M., Evans, P.L., James, A.P., (1990) Org. Synth., 68, p. 64Farington, E., Franchini, M.C., Brown, J.M., (1998) Chem. Commun., p. 277Sato, S., Matsuda, I., Shibata, M., (1989) J. Organomet. Chem., 377, p. 347Hoffmman, H.M.R., Rabe, J., (1985) J. Org. Chem., 50, p. 3849Fort, Y., Berthe, M.C., Caubère, P., (1992) Tetrahedron, 48, p. 6371Corey, E.J., Venkateswalu, A., (1972) J. Am. Chem. Soc., 94, p. 6190Heathcock, C.H., (1984) Asymmetric Synthesis, 3 (PART B). , Morrison, J. D., Ed.Academic: LondonFelkin, H., Chérest, M., Prudent, N., (1968) Tetrahedron Lett., p. 2199Felkin, H., Chérest, M., (1968) Tetrahedron Lett., p. 2205Ahn, N.T., Eisenstein, O., (1977) Nouv. J. Chem., 1, p. 61Jackson, R.S.W., Standen, S.P., Clegg, W., McCamlevy, A., (1992) Tetrahedron Lett., 33, p. 619
The Role Of Ionic Liquids In Co-catalysis Of Baylis-hillman Reaction: Interception Of Supramolecular Species Via Electrospray Ionization Mass Spectrometry
No full textThe Baylis-Hillman reaction is a general and multifaceted method for C - C bond formation in organic synthesis. Using electrospray ionization mass spectrometry in both the positive and negative ion modes, we performed on-line monitoring of the reaction in the presence of imidazolium ionic liquids. Loosely bonded supramolecular species formed by coordination of neutral reagents, products and the protonated forms of zwitterionic Baylis-Hillman intermediates with cations and anions of ionic liquids were gently and efficiently transferred directly from the solution to the gas phase. Mass measurements and structural characterization of these unprecedented species via collisioninduced dissociation in tandem mass spectrometry experiments were performed. The interception of several supramolecular species indicates that ionic liquids co-catalyze Baylis-Hillman reactions by activating the aldehyde toward nucleophilic enolate attack and by stabilizing the zwitterionic species that act as the main BH intermediates. Copyright © 2006 John Wiley & Sons, Ltd.1911731736Baylis, A.B., Hillman, M.E.D., (1972), German Patent 2155113Chem. Abstr. 197277: 34174qMorita, K., Suzuki, Z., Hirose, H., (1968) Bull. Chem. Soc. Jpn, 41, pp. 2815-2815Basavaiah, D., Rao, A.J., Satyanarayama, T., (2003) Chem. Rev, 103, pp. 811-891Almeida, W.P., Coelho, F., (2000) Quim. Nova, 23, pp. 98-101Chem. Abstr. 2000132: 236562Ciganek, E., (1997) Org. React, 51, pp. 201-350Basavaiah, D., Rao, P.D., Hyma, R.S., (1996) Tetrahedron, 52, pp. 8001-8062Silveira, G.P.C., Coelho, F., (2005) Tetrahedron Lett, 46, pp. 6477-6481Mateus, C.R., Coelho, F., (2005) J. Braz. Chem. 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Mass-selection was performed by Q1 using a unitary m/z window, and collisions were performed in the rf-only quadrupole collision cell, followed by mass analysis of product ions by the high-resolution orthogonalreflectron TOF analyzerSuarez, P.A.Z., Dullius, J.E., Einloft, S., DeSouza, R.F., Dupont, J., (1996) Polyhedron, 15, pp. 1217-121
Structure and dynamics of turbulent flows over highly permeable walls
No full textHighly porous materials are found in various industrial applications and environmental flows. In previous studies it was found that a turbulent flow along a highly porous wall experiences a higher skin friction as compared to a solid wall with similar surface roughness when the so-called permeability Reynolds number (Re_K) is larger than O(1). The main objective of the present study was to gain understanding of the characteristic structures and auto-generation mechanisms of turbulence for Re_K >> 1. To this purpose the Volume-Averaged Navier-Stokes (VANS) equations were solved in a Direct Numerical Simulation (DNS) of a turbulent flow through a plane channel with an upper solid wall and a lower porous wall at Re_K = 5.91. The DNS results are in good agreement with available Particle Image Velocimetry (PIV) data for the same flow geometry. A linear stochastic estimation technique was used to capture the structure associated with the characteristic ejection event that contributes most to the Reynolds shear stress near the porous wall. This structure is similar to a horseshoe vortex. Contrary to the conventional hairpin vortex found near solid walls, this horseshoe vortex has a significantly higher inclination angle with the wall and its legs are much shorter. The latter is consistent with the observed absence of low and high-speed streaks near highly permeable walls. Next, the auto-generation mechanisms of the horseshoe vortex were studied in another DNS in which the horseshoe vortex was released in the Reynolds-averaged flow field obtained from the former DNS. Two distinct auto-generation mechanisms were observed: (1) the generation of new structures at the upstream end of the horseshoe vortex, which evolve rapidly into a turbulent spot with an arrowhead shape, and (2) the interaction of the horseshoe vortex with spanwise oriented Kelvin-Helmholtz vortex rollers originating from the inflexion point in the mean velocity profile near the porous wall
Direct numerical simulations of drag reduction in turbulent channel flow over bio-inspired herringbone riblet-texture
No full textThe use of drag reducing surface textures is a promising passive method to reduce fuel consumption. Probably most wellknown is the utilisation of shark-skin inspired ridges or riblets parallel to the mean flow. They can reduce drag up to 10%. Recently another bio-inspired texture based on bird flight feather riblets has been proposed. It differs from the standard riblets in two ways. First, the riblets are arranged in a converging/diverging or herringbone pattern. Second, the riblet height or groove depth changes gradually. Drag reductions as high as 20% have been claimed [2]. The objective of the present work is to study the drag reducing properties and mechanisms of this texture. To that purpose Direct Numerical Simulations (DNSs) of turbulent plane channel flow have been performed. Structured roughness has been applied to both walls and several geometric parameters have been varied. Marginal drag reductions on the order of 2.5% and significant drag increases well beyond 100% were found. The latter is attributed to a strong secondary flow that mixes momentum through the whole channel. In future optimization studies we might look for conditions at which secondary motions affect the near-wall cycle of turbulence only
The Influence Of Protecting Groups On The Diastereoselectivity Ofcatalyticheterogeneous Hydrogenation Of Baylis-hillman Adducts
No full textIn this communication we describe our recent results from a study on catalytic heterogeneous hydrogenation reactions of Baylis-Hillman adducts. Depending on the protecting groups used on the secondary hydroxyl group of these adducts, it is possible to obtain a high degree of diastereoselection. For silylated Baylis-Hillman adducts a high syn diastereoselectivity has been obtained. However, when secondary Baylis-Hillman hydroxyl groups were unprotected or protected as acetate a moderate anti selectivity was attained. The adducts protected as methyl ether gave poor syn diastereoselectivity.200310443467Drewes, S.E., Roos, G.H.P., (1988) Tetrahedron, 44, p. 4653Basavaiah, D., Rao, P.D., Hyma, R.S., (1996) Tetrahedron, 52, p. 8001Ciganek, E., (1997) Organic Reactions, 51, p. 201. , John Wiley New York, Chapter 2Almeida, W.P., Coelho, F., (2000) Quim. Nova, 23, p. 98(2000) Chem. Abstr., 132, pp. 236532eBasavaiah, D., Rao, A.J., Satyanarayana, T., (2003) Chem. 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Electrochemical Study Of Methyl 2-[p-nitrophenyi(hydroxy)methyl]acrylate, An Anticancer Drug, In The Presence Of Gsh And Dsdna
No full textElectrochemical experiments (CV, DPV, SWV, CPE) with methyl 2-[p-nitrophenyl(hydroxy) methyl] acrylate (1) were performed in protic (EtOH + phosphate buffer 1:9, 0.1 mol L-1, pH 6.9 and EtOH + phosphate buffer: 1:9, 0.1 mol L1, pH 9.4) and aprotic (DMF + TBAP, 0.1 mol L-1) media. The reduction behaviours were typical of nitroaromatics, with an additional wave, in aprotic medium, related to the reduction of the olefin. Electrolysis, in protic media, furnished a reduced dimer. The incubation of 1 into a dsDNA biosensor revealed, that, after reduction of the nitroaromatic function, diagnostic oxidation peaks of the nucleobases were observed, indicative of interaction between them. GSH influenced the reduction behaviour of 1. Direct reduction of 1, in phosphate buffer, pH 9.38, to a stable nitroso/GSH adduct is facilitated. These electrochemical results help in the understanding of the anticancer activity of 1 that can be considered a hypoxia targeted bioreductive agent with a glutathione depleting function. copyright The Electrochemical Society.329137146Rauf, S., Gooding, J.J., Akhtar, K., Ghauri, M.A., Rahman, M., Anwar, M.A., Khalid, A.M., (2005) J. Pharm. Biomed. Anal, 37, p. 205Russo, A., Degraff, W., Friedman, N., Mitchell, J.B., (1986) Cancer Res, 46, p. 2845Tew, K.D., (1994) Cancer Res, 54, p. 4313Berube, L.R., Farah, S., McClelland, R.A., Rauth, A.M., (1992) Int. J. Radiat. Oncol. Biol. Phys, 22, p. 817Griffith, O.W., Meister, A., (1979) J. Biol. Chem, 254, p. 7558Williamson, J.M., Boettcher, B., Meister, A., (1982) Proc. Natl. Acad. Sci. USA, 79, p. 6246McCarthy, T.J., Hayes, E.P., Schwartz, C.S., Witz, G., (1994) Fundam. Appl. Toxicol, 22, p. 543Kohn, L.K., Pavam, C.H., Veronese, D., Coelho, F., De Carvalho, J.E., Almeida, W.P., (2006) Eur. J. Med. Chem, 41, p. 738De Abreu, F.C., Ferraz, P.A.L., Goulart, M.O.F., (2002) J. Braz. Chem. Soc, 13, p. 19Squella, J.A., Bollo, S., Núñez-Vergara, L.J., (2005) Current Org. Chem, 9, p. 565Julião, M.D.D.S., Ferreira, E.I., Ferreira, N.G., Serrano, S.H.P., (2006) Electrochim. Acta, 51, p. 5080A. M. O. Brett, M.O.F.Goulart and F.C. de Abreu, Biosens. Bioelectron., 17, 913 (2002)Brett, A.M.O., Serrano, S.H.P.J., Piedade, A.P., (1999) Comprehensive Chemical Kinetics, 37, pp. 91-119. , R. G. Compton and H. G. Hancock, Editors, Elsevier: AmsterdamCoelho, F., Almeida, W.P., Mateus, C.R., Veronese, D., Lopes, E.C.S., Silvira, G.P.S., Rossi, R.C., Pavam, C.H., (2002) Tetrahedron, 58, p. 7437Lund, H., Cathodic Reduction of Nitro and Related Compounds (2001) Organic Electrochemistry, p. 389. , 4th Ed, H. Lund and O. Hammerich, Editors, p, Marcel Dekker, New YorkMcClelland, R.A., (1990) Selective Activation of Drugs by Redox Processes, p. 125. , G.E. Adams, A. Breccia, E.M. Fielden and P. Wardman, Editors, p, Plenum Press, New YorkTocher, J.H., Edwards, D.I., (1995) Biochem. Pharmacol, 50, p. 136
Mechanics of dense suspensions in turbulent channel flows
No full textDense suspensions are usually investigated in the laminar limit where inertial effects are insignificant. When the flow rate is high enough, i.e. at high Reynolds number, the flow may become turbulent and the interaction between solid and liquid phases modifies the turbulence we know in single-phase fluids. In the present work, we study turbulent channel flows laden with finite-size particles at high volume fraction by means of Direct Numerical Simulations. A direct-forcing Immersed Boundary Method has been adopted to couple liquid and solid phases. We will show that the turbulence is attenuated in dense cases, even though the overall drag is increased because of the particle contribution to the total stress
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