New insights into the genetic etiology of Alzheimer's disease and related dementias.

Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele

Organophilic Clays: Characteristics, Preparation Methods, Intercalation Compounds And Characterization Techniques [argilas Organofílicas: Características, Metodologias De Preparação, Compostos De Intercalação E Técnicas De Caracterização]

Clays are materials used since historical periods and nowadays have several applications due to their interesting properties. The surface modification of clays is one area that has received enough attention from researchers because through modification it is possible to prepare new materials and find applications. The purpose of this paper is to present a review on the use of clays for obtaining organophilic clays, especially those used in polymeric nanocomposites. Several studies have been done based on different techniques and process conditions of these materials. The review includes clays of different regions, different modification agents and applications.54330213226A. P. Chagas, Argilas: as essências da terra, Editora Moderna, S. Paulo (1996)P. S. Santos, Ciência e Tecnologia de Argilas, 2 a Edição, Editora Edgard Blucher, S. Paulo (1989) 66-68A. S. Filho, Diss. Mestrado, Universidade Estadual de Campinas (1998)Santos, C.P.F., Melo, D.M.A., Melo, M.A.F., Sobrinho, E.V., (2002) Cerâmica, 48 (308), p. 178Bergaya, F., Lagaly, G., (2001) Appl. Clay Sci, 19, p. 1Merinska, D., Malac, Z., Pospisil, M., Weiss, Z., Chmielova, M., Capkova, P., Simonik, J., (2002) Comp. Interf, 9, p. 529Kakegawa, N., Ogawa, M., (2002) Appl. Clay Sci, 22, p. 137Bharadwaj, R.K., Macromolecules, V., (2001), 9189G. Lagaly, S. Ziesmer, Adv. Col. and Int. Sci. 100-102 (2003) 105Utracki, L.A., (2004) Clay Containing Polymeric Nanocomposites, , Rapra TechnologyAlexandre, M., Dubois, P., (2000) Mater. Sci. Eng, 28, p. 1Vougaris, D., Petridis, D., (2002) Polymer, 43, p. 2213Gorassi, G., Tortora, M., Vittoria, V., Kaempfer, D., Mülhaupt, R., (2003) Polymer, 44, p. 3679Akyüz, S., Akyüz, T., (2003) J. Mol. Struc, 651-653, p. 205Tamura, K., Nakazawa, H., (1996) Clays Clay Min, 44, p. 501Klapyta, Z., Fujita, T., Iyi, N., (2001) Appl. Clay Sci, 19, p. 5Chang, J.H., An, Y.U., Cho, D., Giannelis, E.P., (2003) Polymer, 44, p. 3715Klapyta, Z., Gawel, A., Fujita, T., Iyi, N., (2003) Clay Min, 38, p. 151J. Markarian, Plastics Additives & Compounding (11-12/2005) 18G. Chigwada, C. A. Wilkie, Pol. Degrad. Stab. 3 (2003), 551Kwolek, T., Hodorowicz, M., Stadmicka, K., Czapkiewicz, J., (2003) J. Coll. Interf. Sci, 264, pp. 14-19Akçay, M., (2004) J. Coll. Interf. Sci, 280, p. 299Yilmaz, N., Yapar, S., (2004) Appl. Clay Sci, 27, p. 223Yapar, S., Özbudak, V., Lopes, A., (2005) J. Hazardous Mater, 121, p. 135Beall, G.W., Goss, M., (2004) Appl. Clay Sci, 27, p. 179Xi, Y., Ding, Z., He, H., Frost, R.L., (2005) Spectrochim. Acta Part A, 61, p. 515S. S. Araújo, D. L. A. C. S. Andrade, L. H. Carvalho, A. S. Gomes, S. M. L. Silva, Plást. Ind. (12/2005) 104F. R. V. Díaz, Tese de Doutorado, Universidade de S. Paulo, S. Paulo (1994)Zhang, Y.-Q., Lee, J.-H., Rhee, J.M., Rhee, K.Y., (2004) Comp. Sci. Tech, 64, p. 1383Vaia, R.A., Teukolsky, R.K., Giannelis, E.P., (1994) Chem. Mater, 6, p. 1017Moraru, V.N., (2001) Appl. Clay Sci, 19 (11-26), p. 1918Park, S.-J., Seo, D.I., Lee, J.-R., (2002) J. Coll. Interf. Sci, 251, p. 160Arroyo, M., López-Manchado, M.A., Herrero, B., (2003) Polymer, 44, p. 2447Hongping, H., Ray, F., Jianxi, Z., (2004) Spectrochim. Acta Part A, 60, p. 2853Kozak, M., Domba, L., (2004) J. Phys. Chem. Sol, 65, p. 441Majdan, M., Maryuk, O., Pikus, S., Olszewska, E., Kwiatkowski, R., Skrzypek, H., (2005) J. Mol. Struct, 70, p. 203Xi, Y., Ding, Z., He, H., Frost, R.L., (2004) J. Coll. Interf. Sci, 277, p. 116Zhu, J., He, H., Wen, X., Deng, F., (2005) J. Coll. Sci. Interf. Sci, 286, p. 239Yoshimoto, S., Osashi, F., Kameyama, T., (2005) Solid State Comm, 136, p. 251LeBaron, P.C., Wang, Z., Pinnavaia, T.J., (1999) Appl. Clay Sci, 15, p. 11Hackett, E., Manias, E., Giannelis, E.P., (1998) J. Chem. Phys, 108, p. 7410Morrison, R., Boyd, R., (1996) Química Orgânica, p. 960. , Fund. Calouste Gulbenkian, LisboaLiu, X., Wu, Q., (2001) Polymer, 42, pp. 10013-10019Shen, Y.H., (2001) Chemosphere, 44, p. 989Yao, H., Zhu, J., Morgan, A.B., Wilkie, C.A., (2002) Polym. Eng. Sci, 42, p. 1808Awad, W.H., Gilman, J.W., Nuden, M., Harris Jr., R.H., Sutto, T.E., Callahan, J., Truvole, P.C., Fox, D.M., (2004) Thermochim. Acta, 409, p. 3Y-Q. Zhang, J-L. Lee, H-J. Jang, C.-W. Nah, Composites: Part B 35 (2003) 133Sánchez-Sólis, A., Romero-Ibarra, I., Estrada, M.R., Calderas, F., Manero, O., (2004) Polym. Eng. Sci, 44, p. 1094He, H., Duchet, J., Galy, J., Gerard, J.-F., (2005) J. Coll. Interf. Sci, 288, p. 171Pozsgay, A., Cráter, T., Százdi, L., Müller, P., Sajó, I., Pukánszky, B., (2003) Europ. Polym. J, 40, p. 27Shishan, W., Dingjun, J., Xiaodong, O., Fen, W., Jian, S., (2004) Polym. Eng. Sci, 44, p. 2070Lee, S.Y., Kim, S.J., (2002) Coll. Surf. A: Physicochem. Eng. Aspects, 211, p. 19Lee, S.Y., Cho, W.J., Kim, K.J., Ahn, J.H., Lee, M., (2005) J. Coll. Interf. Sci, 284, p. 667Aguiar, M.R.M.P., Novaes, A.C., (2003) Quím. Nova, 25, p. 1145Lee, J.Y., Lee, H.K., (2004) Mater. Chem. Phys, 85, p. 41Akçay, M., (2006) J. Coll. Interf. Sci, 296, p. 16Gemeay, A.H., El-Sherbing, A.S., Zaki, A.B., (2005) J. Coll. Interf. Sci, 245, p. 116Breakwell, I.K., Homer, J., Lawrence, M.A.M., Mcwhinnie, W.R., (1995) Polyhedron, 14, p. 251

Mechanical Properties Of Polypropylene And Organophilic Montmorillonite Nanocomposites [propriedades Mecânicas De Nanocompósitos De Polipropileno E Montmorilonita Organofílica]

Nanocomposites of polypropylene and commercial montmorillonite organophilic Cloisite 20A containing 2.5%, 5%, 7.5% and 10% of clay with polypropylene-graft-maleic anhydride as coupling agent were prepared through the melt intercalation by twin-screw extruder. The materials were characterized by x-ray diffraction, tensile and impact properties according to ASTM D638 and D256 test methods, respectively. The x-ray diffraction results showed exfoliated or intercalated structures for different concentrations of the clay. The tensile modulus improved with the increase of the amount of the clay while the impact strength showed unsatisfactory results.162136140Bourbigot, S., Devaux, E., Flambard, X., (2002) Polym. Degrad. and Stab., 75, pp. 397-402Alexandre, M., Dubois, P., (2000) Materials Science and Engineering, 28, pp. 1-63Beyer, G., (2002) Plastics Additives & Compounding, pp. 22-28Santos, P.S., (1989) Ciência e Tecnologia de Arguas, , Ed. Edgard Blucher, São PauloGorassi, G., (2003) Polymer, 44, pp. 2271-2279Zheng, X., Wilkie, C.A., (2003) Polym. Degrad. and Stab., 81 (1), pp. 1-12LeBaron, P.C., Wang, Z., Pinnavaia, T.J., (1999) Applied Clay Science, 15, pp. 11-29Krishnamoorti, R., Yurekli, K., (2000) Current Opinion in Coll. & Interf. Sci., 6, pp. 464-470Hambir, S., Bulakh, N., Jog, J.P., (2002) Polym. Eng. and Sci., 42 (9), pp. 1800-1807Yao, H., (2002) Polym. Eng. and Sci., 42 (9), pp. 1808-1814Pantoustier, N., (2002) Polym. Eng. and Sci., 42 (9), pp. 1928-1937Stewart, R., (2004) Plastics Engineering, pp. 22-29(2000) Standard Test Method for Tensile Properties of Plastics, , ASTM D638-99, v. 08.01(2000) Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics - Method A, , ASTM D256-97, v.08.01Lee, E.C., Mielewski, D.F., Baird, R.J., (2004) Polym. Eng. and Sci., 44 (9), pp. 1773-1782Lee, K.Y., Goetler, L.A., (2004) Polym. Eng. and Sci., 44 (6), pp. 1103-1111Ton-That, M.-T., Perrin-Sarazin, F., Cole, K.C., (2004) Polym. Eng. and Sci., 44 (7)García-López, D., (2003) European Polym. Journal, 39, pp. 945-950Liu, X., Wu, Q., (2001) Polymer, 42, pp. 10013-1001

Morphology, Structure And Mechanical Properties Of Polypropylene Modified With Organophilic Montmorillonite

The aim of this work is to study the properties of systems based on polypropylene (PP) and commercial organophilic montmorillonite, prepared by melt intercalation. Because of the non polar character of PP, the polypropylene-graft-maleic anhydride (PP-g-MA) was used as compatibilizer. Materials containing 2.5, 5, 7.5 and 10% of clay and PP, and two extra compositions containing only PP and 15 and 30% of PP-g-MA were processed using a twin-screw extruder. The level of clay dispersion was characterized by X ray diffraction, showing exfoliated/intercalated structures for different concentrations of clay. The crystallization behavior was studied by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) with hot stage. Tensile properties were also studied and presented a moderate improvement with increase in clay concentration.2215460Paul, D.R., Robeson, L.M., (2008) Polymer, 34, p. 3187. , http://dx.doi.org/10.1016/j.polymer.2008.04.017Sharma, S.K., Nayak, S.K., (2009) Polym. Degrad. Stab., 94, p. 132. , http://dx.doi.org/10.1016/j.polymdegradstab.2008.09.004Lai, S.-M., Chen, W.-C., Zhu, X.S., (2009) Compos. Part A, 40, p. 754. , http://dx.doi.org/10.1016/j.compositesa.2009.03.006Modesti, M., Lorenzetti, A., Bon, D., Besco, S., (2006) Polym. Degrad. Stab., 91, p. 672. , http://dx.doi.org/10.1016/j.polymdegradstab.2005.05.018Benetti, E.M., Causin, V., Marega, C., Marigo, A., Ferrara, G., Ferraro, A., Consalvi, M., Fantinel, F., (2005) Polymer, 46, p. 8275. , http://dx.doi.org/10.1016/j.polymer.2005.06.056Százdia, L., Pukánszky Jr., B., Foldesa, E., Pukánszkya, B., (2005) Polymer, 46, p. 8001. , http://dx.doi.org/10.1016/j.polymer.2005.06.108Zhou, Y., Rangari, V., Mahfuz, H., Jeelani, S., Mallick, P.K., (2005) Mater. Sci. Eng. A, 402, p. 109. , http://dx.doi.org/10.1016/j.msea.2005.04.014Malucelli, G., Ronchetti, S., Lak, N., Priola, A., Dintcheva, N.T., Mantia, F.P., (2007) Eur. Polym. J., 43, p. 328. , http://dx.doi.org/10.1016/j.eurpolymj.2006.11.024Dong, Y., Bhattacharyya, D., (2008) Compos. Part A, 39, p. 1177. , http://dx.doi.org/10.1016/j.compositesa.2008.03.006Hambir, S., Bulakh, N., Jog, J.P., (2002) Polym Eng.Sci., 42, p. 1800. , http://dx.doi.org/10.1002/pen.11072Yao, H., Zhu, J., Morgan, A.B., Wilkie, C.A., (2002) Polym Eng.Sci., 42, p. 1808. , http://dx.doi.org/10.1002/pen.11073Pavlidou, S., Papaspyrides, C.D., (2008) Prog. Polym. Sci., 33, p. 1119. , http://dx.doi.org/10.1016/j.progpolymsci.2008.07.008Fanegas, N., Gómez, M.A., Marco, C., Jiménez, I., Ellis, G., (2007) Polymer, 48, p. 5324. , http://dx.doi.org/10.1016/j.polymer.2007.07.004Lonkar, S.P., Morlat-Therias, S., Capera, N., Leroux, F., Gardette, J.L., Singh, R.P., (2009) Polymer, 50, p. 1505. , http://dx.doi.org/10.1016/j.polymer.2009.01.031Xu, J.-T., Wang, Q., Fan, Z.-Q., (2005) Eur. Polym. J., 41, p. 3011. , http://dx.doi.org/10.1016/j.eurpolymj.2005.04.042Lv, Z., Wang, K., Qiao, Z., Wang, W., (2010) Mater Des., 31, p. 3804. , http://dx.doi.org/10.1016/j.matdes.2010.03.028Shi, J., Yang, X., Wang, X., Lu, L., (2010) Polym Test., 29, p. 596. , http://dx.doi.org/10.1016/j.polymertesting.2010.03.007Zhang, Z., Wang, C., Yang, Z., Chen, C., Mai, K., (2008) Polymer, 49, p. 5137. , http://dx.doi.org/10.1016/j.polymer.2008.09.009Zhou, H., Ying, J., Xie, X., Liu, F., Li, D., (2010) Polym Test., 29, p. 915. , http://dx.doi.org/10.1016/j.polymertesting.2010.06.004Hao, W., Yang, W., Cai, H., Huang, Y., (2010) Polym. Test., 29, p. 527. , http://dx.doi.org/10.1016/j.polymertesting.2010.03.004Lonka, S.P., Morlat-Therias, S., Capera, N., Leroux, F., Gardette, J.L., Singh, R.P., (2009) Polymer, 50, p. 1505. , http://dx.doi.org/10.1016/j.polymer.2009.01.031Lei, S.G., Hoa, S.V., Ton-That, M.-T., (2006) Compos. Sci. Technol., 66, p. 1274. , http://dx.doi.org/10.1016/j.compscitech.2005.09.012Maiti, P., Nam, P.H., Okamoto, M., Kotaka, T., Hasegawa, N., Usuki, A., (2002) Polym. Eng.Sci., p. 1864. , http://dx.doi.org/10.1002/pen.11079, 42.9Yuan, Q., Awate, S., Misra, R.D.K., (2006) Eur. Polym. J., 42, p. 1994. , http://dx.doi.org/10.1016/j.eurpolymj.2006.03.012Paiva, L.B., Morales, A.R., Guimarães, T.R., (2007) Mater. Sci. Eng. A, 447, p. 261. , http://dx.doi.org/10.1016/j.msea.2006.10.066Vladimirov, V., Betchev, C., Vassiliou, A., Papageorgiou, G., Bikiaris, D., (2006) Compos. Sci. Technol., 66, p. 2935. , http://dx.doi.org/10.1016/j.compscitech.2006.02.010Cho, K.W., Li, F.K., Choi, J., (1999) Polymer, 40, p. 1719. , http://dx.doi.org/10.1016/S0032-3861(98)00404-2Perrin-Sarazin, F., Ton-That, M.-T., Bureau, M.N., Denaul, J., (2005) Polymer, 46, p. 11624. , http://dx.doi.org/10.1016/j.polymer.2005.09.076Avella, M., Cosco, S., Di Lorenzo, M.L., Di Pace, E., Errico, M.E., Gentile, G., (2006) Eur. Polym. J., 42, p. 1548. , http://dx.doi.org/10.1016/j.eurpolymj.2006.01.009Liu, X., Wu, Q., (2001) Polymer, 42, p. 10013. , http://dx.doi.org/10.1016/S0032-3861(01)00561-

Organoclays: Properties, Preparation And Applications

The objective of this paper is to give an overview of properties, synthesis and applications, and to describe the research performed until the present moment. A significant amount of research has been done in this area, including different synthesis techniques, modifications with several chemical compounds as quaternary alkylammonium salts and also biomolecules as enzymes that provide applicability in a variety of fields. The review is particularly focused on bentonite and polymer nanocomposites, an important area of the nanotechnology. © 2008 Elsevier B.V. All rights reserved.421-2824Akçay, M., Characterization and determination of the thermodynamic and kinetic properties of p-CP adsorption onto organophilic bentonite from aqueous solution (2004) J. Colloid Interface Sci., 280, pp. 299-304Akçay, M., Characterization and adsorption properties of tetrabutilammonium montmorillonite (TBAM) clay: Thermodynamic and kinetic calculations (2006) J. Colloid Interface Sci., 296, pp. 16-21Akyüz, S., Akyüz, T., FT-IR spectroscopic investigations of surface and intercalated 2-aminopyrimidine adsorbed on sepiolite and montmorillonite from Anatolia (2003) J. Mol. Struct., 651-653, pp. 205-210Araújo, S.S., Andrade, D.L.A.C.S., Carvalho, L.H., Gomes, A.S., Silva, S.M.L., Quais são os efeitos da velocidade de processamento sobre as propriedades mecânicas de formulações PP/bentonita (2005) Plástico Industrial, pp. 104-116Araújo, E.M., Melo, T.J.A., Oliveira, A.D., Araújo, H.L.D., Araújo, K.D., Barbosa, R., Preparação de argilas organofílicas e desenvolvimento de nanocompósitos com matrizes poliméricas de polietileno e nylon6 (2006) Polímeros: Ciência e Tecnologia, 16, pp. 38-45. , Parte 1: Comportamento MecânicoArroyo, M., López-Manchado, M.A., Herrero, B., Organo-montmorillonite as substitute of carbon black in natural rubber compounds (2003) Polymer, 44, pp. 2447-2453Awad, W.H., Gilman, J.W., Nyden, M., Harris Jr., R.H., Sutto, T.E., Callahan, J., Truvole, P.C., Fox, D.M., Thermal degradation studies of alkyl-imidazolium salts and their application in nanocomposites (2004) Thermochim. Acta, 409, pp. 3-11Beall, G.W., Goss, M., Self-assembly of organic molecules on montmorillonite (2004) Appl. Clay Sci., 27, pp. 179-186Beneke, K., Lagaly, G., (2002) European Clay Group Association Newsletter, pp. 57-78. , 5Bergaya, F., Lagaly, G., Surface modifications of clay minerals (2001) Appl. Clay Sci., 19, pp. 1-3Bergaya, F., Theng, B.K.G., Lagaly, G., (2006) Handbook of Clay Science. First Edition, , ElsevierBilgiç, C., Investigation of the factors affecting organic cation adsorption on some silicates minerals (2005) J. Colloid Interface Sci., 281, pp. 33-38Bongiovanni, R., Monchietto, R., Sangermano, M., Malucelli, G., Priola, A., Epoxy coatings, via cationic UV-curing, containing nanodispersed phyllosilicates (2003) Annais of XVI Convegno Italiano di Scienza e Tecnologia delle Macromolecole, Pisa, Italy, pp. 245-246Bottino, F., Fragalà, I., Malandrino, G., Orestano, A., Pollicino, A., Polystyrene clay nanocomposites prepared with polymerizable imidazolium surfactants (2003) Annais of XVI Convegno Italiano di Scienza e Tecnologia delle Macromolecole, Pisa, Italy, pp. 229-230Bradley, W.F., Molecular associations between montmorillonite and some polyfunctional organic liquids (1945) J. Am. Chem. Soc., 67, pp. 975-981Breakwell, K.I., Homer, J., Lawrence, M.A.M., McWhinnie, W.R., Studies of organophilic clays: the distribution of quaternary ammonium compounds on clay surfaces and the role of impurities (1995) Polyedron, 14, pp. 2511-2518Burmistr, M.V., Sukhy, K.M., Shilov, V.V., Pissis, P., Spanoudaki, A., Sukha, I.V., Tomilo, V.I., Gonza, Y.P., Synthesis, structure, thermal and mechanical properties of nanocomposites based on a linear polymers and layered silicates modified by polymeric quaternary ammonium salts (ionenes) (2005) Polymer, 46, pp. 12226-12232Causserand, C., Jover, K., Aimar, P., Meireles, M., Modification of clay cake permeability by adsorption of protein (1997) J. Membr. Sci., 137, pp. 31-44Chaiko, D.J., New poly(ethylene oxide)-clay composites (2003) Chem. Mater., 15, pp. 1105-1110Chang, J.-H., An, Y.V., Cho, D., Giannelis, E.P., Poly(lactic acid) nanocomposites: comparison of their properties with montmorillonite and synthetic mica (II) (2003) Polymer, 44, pp. 3715-3720Chigwada, G., Wang, D.D., Wilkie, C.A., Polystyrene nanocomposites based on quinolinium and pyridinium surfactants (2006) Polym. Degrad. Stab., 91, pp. 848-855Chigwada, G., Wang, D.D., Jiang, D.D., Wilkie, C.A., Styrenic nanocomposites prepared using a novel biphenyl-containing modified clay (2006) Polym. Degrad. Stab., 91, pp. 755-762Contreras, V., Cafiero, M., Silva, S.D., Rosales, C., Perera, R., Matos, M., Characterization and tensile properties of ternary blends with PA-6 nanocomposites (2006) Polym. Eng. Sci., 46, pp. 1111-1120Costa Filho, A.P., Gomes, A.S., Lucas, E.S., Preparação e caracterização de organobentonita modificada com ionenos alifáticos (2005) Polímeros: Ciência e Tecnologia, 15, pp. 212-217Favre, A., Lagaly, G., Organo-bentonites with quaternary alkylammonium ions (1991) Clay Miner., 26, pp. 19-32Filho, N.L.D., Carmo, D.R., Study of an organically modified clay: selective adsorption of heavy metal ions and voltammetric determination of mercury (II) (2006) Talanta, 68, pp. 919-926Gemeay, A.H., El-Sherbiny, A.S., Zaki, A.B., Adsorption and kinetic studies of the intercalation of some organic compounds onto Na+-montmorillonite (2002) J. Colloid Interface Sci., 245, pp. 116-125Gieseking, J.E., The mechanism of cation exchange in the montmorillonite-beidellite-nontronite type of clay minerals (1939) Soil Sci., 47, pp. 1-14Gopinath, S., Sugunan, S., Enzymes immobilized on montmorillonite K10: Effect of adsorption and grafting on the surface properties and the enzyme activity (2007) Appl. Clay Sci., 35, pp. 67-75Gorassi, G., Tortora, M., Vittoria, V., Kaempfer, D., Mülhaupt, R., Transport properties of organic vapor in nanocomposites of organophilic layered silicate and syndiotactic polypropylene (2003) Polymer, 44, pp. 3679-3685Hackett, E., Manias, E., Giannelis, E.P., Molecular dynamics simulations of organically modified silicates (1998) J. Chem. Phys., 108, pp. 7410-7415Hasegawa, N., Okamoto, H., Kato, M., Usuki, M., Preparation and mechanical properties of polypropylene-clay hybrids based on modified polypropylene and organophilic clay (2000) J. Appl. Polym. Sci., 78, pp. 1918-1922He, H., Duchet, J., Galy, J., Gerard, J.-F., Grafting of swelling clay materials with 3-aminopropyltriethoxysilane (2005) J. Colloid Interface Sci., 288, pp. 171-176Herrera, N.N., Letoffe, J.-M., Reymond, J.-P., Bourgeat-Lami, E., Silylation of laponite clay particles with monofunctional and trifunctional vinyl alkoxysilanes (2005) J. Mater. Chem., 15, pp. 863-871Hongping, H., Ray, F., Jianxi, Z., Infrared study of HDTMA+ intercalated montmorillonite (2004) Spectrochim. Acta, Part A, 60, pp. 2853-2859Jordan, J.W., Organophilic bentonites I. Swelling in organic liquids (1949) J. Phys. Colloid Chem., 53, pp. 294-306Jordan, J.W., Organophilic bentonites III. Inherent properties (1954) Colloid Polym. Sci., 137 (1), pp. 40-48Jordan, J.W., Hook, B.J., Finlayson, C.M., Organophilic bentonites II. Organic liquid gels (1950) J. Phys. Colloid Chem., 54, pp. 1196-1208Kakegawa, N., Ogawa, M., The intercalation of b-carotene into organophilic interlayer space of dialkyldimethylammonium-montmorillonites (2002) Appl. Clay Sci., 22, pp. 137-144Kalra, S., Pant, C.K., Pathak, H.D., Mehata, M.S., Studies on the adsorption of peptides of glycine/alanine on montmorillonite clay with or without co-ordinated divalent cations (2003) Colloids Surf., A Physicochem. Eng. Asp., 212, pp. 43-50Kim, J.H., Koo, C.M., Choi, Y.S., Wang, K.H., Chung, I.J., Preparation and characterization of polypropylene/layered silicate nanocomposites using an antioxidant (2004) Polymer, 45, pp. 7719-7727Klapyta, Z., Fujita, T., Iyi, N., Adsorption of dodecyl- and octadecyltrimethylammonium ions on a smectite and synthetic micas (2001) Appl. Clay Sci., 19, pp. 5-10Klapyta, Z., Gawel, A., Fujita, T., Iyi, N., Structural heterogeneity of alkylammonium-exchanged, synthetic fluorotetrasilisic mica (2003) Clay Miner., 38, pp. 151-160Kozak, M., Domba, L., Adsorption of the quaternary ammonium salts on montmorillonite (2004) J. Phys. Chem. Solids, 65, pp. 441-445Kwolek, T., Hodorowicz, M., Standnick, K., Czapkiewicz, J., Adsorption isotherms of homologous alkyldimethyl-benzylammonium bromides on sodium montmorillonite (2003) J. Colloid Interface Sci., 264, pp. 14-19Lagaly, G., Characterization of clays by organic compounds (1981) Clay Miner., 16, pp. 1-21Lagaly, G., Clay-organic interactions (1984) Phil. Trans. R. Soc. Lond. A, 311, pp. 315-332Lagaly, G., Interaction of alkyamines with differents types of layered compounds (1986) Solid State Ionics, 22, pp. 43-51Lagaly, G., Weiss, A., Determination of the layer charge in mica-type layer silicates (1969) Proceedings of the International Clay Conference, Tokyo, pp. 61-80. , 1Lagaly, G., Gonzalez, M.F., Weiss, A., Problems in layer-charge determination of montmorillonites (1976) Clay Miner., 11, pp. 173-187Lee, S.Y., Kim, S.J., Expansion characteristics of organoclay as a precursor to nanocomposites (2002) Colloids Surf., A Physicochem. Eng. Asp., 211, pp. 19-26Lee, J.Y., Lee, H.K., Characterization of organobentonite used for polymer nanocomposites (2004) Mater. Chem. Phys., 85, pp. 410-415Lee, S.Y., Echo, W.J., Kim, K.J., Ahn, J.H., Lee, M., Interaction between cationic surfactants and montmorillonites under nonequilibrium condition (2005) J. Colloid Interface Sci., 284, pp. 667-673Li, J., Ton-That, M.-T., Tsai, S.-J., PP-Based nanocomposites with various intercalant types and intercalant coverages (2006) Polym. Eng. Sci., 46, pp. 1060-1068Liu, X., Wu, Q., PP/clay nanocomposites prepared by grafting-melt intercalation (2001) Polymer, 42, pp. 10013-10019MacEwan, D.M.C., Identification of the montmorillonite group of minerals by X-rays (1944) Nature, 154, pp. 577-578Majdan, M., Maryuk, O., Pikus, S., Olszewska, E., Kwiatkowski, R., Skrzypek, H., Equilibrium, FTIR, scanning electron microscopy and small wide angle X-ray scattering studies of chromates adsorption on modified bentonite (2005) J. Mol. Struct., 70, pp. 203-211Markarian, J., Automotive and packaging offer growth opportunities for nanocomposites (2005) Plast. Addit. Compound., pp. 18-25. , (November/December)Mbouguen, J.K., Ngameni, E., Walcarius, A., Organoclay-enzyme film electrodes (2006) Anal. Chimica Acta, 578, pp. 145-155Merinska, D., Malac, Z., Pospisil, M., Weiss, Z., Chmielova, M., Capkova, P., Simonik, J., Polymer/clay nanocomposites on MMT/ODTA intercalates (2002) Comp. Interf., 9, pp. 529-540Moore, D.M., Reynolds Jr., R.C., (1997) X-Ray diffraction and the identification and analysis of clay minerals. second edition, , Oxford, New YorkMoraru, V.N.M., Structure formation of alkylammonium montmorillonites in organic media (2001) Appl. Clay Sci., 19, pp. 11-26Moronta, A., Ferrer, V., Quero, J., Arteaga, G., Chore, E., Influence of preparation method on the catalytic properties of acid-activated tetramethylammonium-exchanged clays (2002) Appl. Catal., A Gen., 230, pp. 127-135Naidja, A., Huang, P.M., Bollag, J.-M., Activity of tyrosinase immobilized on hydroxyaluminum-montmorillonite complexes (1997) J. Mol. Catal., A Chem., 115, pp. 305-316Ogawa, M., Handa, T., Kuroda, K., Kato, C., Formation of organoammonium-montmorillonites by solid-solid reactions (1990) Chem. Lett., 19, pp. 71-74Öztürk, N., Tabak, A., Akgöl, S., Denizli, A., Newly synthesized bentonite-histidine (Bent-Hist) micro-composite affinity sorbents for IgG adsorption (2007) Colloids Surf., A Physicochem. Eng. Asp., 301, pp. 490-497Park, S.-J., Seo, D.I., Lee, J.-R., Surface modification on montmorillonite on surface acid-base characteristics of clay and thermal stability of epoxy/clay nanocomposites (2002) J. Colloid Interface Sci., 251, pp. 160-165Patel, H.A., Somani, R.S., Bajah, H.C., Jasra, R.V., Preparation and characterization of phosphonium montmorillonite with enhanced thermal stability (2007) Appl. Clay Sci., 35, pp. 194-200Pinto, M.R.O., Júnior, M.M.A., Silva, S.M., Carvalho, L.H., Influência da modificação química de uma carga mineral nanoparticulada nas propriedades mecânicas e no envelhecimento térmico de compósitos de poliuretano/sisal (2005) Polímeros: Ciência e Tecnologia, 15, pp. 313-319Pozsgay, A., Fráter, T., Százdi, L., Müler, P., Sajó, I., Pukánszky, B., Gallery structure and exfoliation of organophilized montmorillonite: effect on composite properties (2004) Eur. Polym. J., 40, pp. 27-36Qin, H., Zhang, S., Zhao, C., Hu, G., Yang, M., Flame retardant mechanism of polymer/clay nanocomposites based on polypropylene (2005) Polymer, 46, pp. 8386-8395Ramos Filho, F.G., Mélo, T.J.A., Rabello, M.S., Silva, S.M.L., Thermal stability of nanocomposites based on polypropylene and bentonite (2005) Polym. Degrad. Stab., 89, pp. 383-392Rodríguez-Sarmiento, D.C., Pinzón-Bello, J.A., Adsorption of sodium dodecylbenzene sulfonate on organophilic bentonites (2001) Appl. Clay Sci., 18, pp. 173-181Sánchez-Solís, A., Ibarra-Romero, I., Estrada, M.R., Calderas, F., Manero, O., Mechanical and rheological studies on polyethylene terphtalate-montmorillonite nanocomposites (2004) Polym. Eng. Sci., 44, pp. 1094-1102Sanjay, G., Sugunan, S., Glucoamylase immobilized on montmorillonite: Synthesis, characterization and starch hydrolysis activity in a fixed bed reactor (2005) Catal. Comm., 6, pp. 525-530Santos, P.S., (1989) Ciência e Tecnologia de Argilas. second ed., , Edgard Blucher, São PauloShen, Y.H., Preparations of organobentonite using nonionic surfactants (2001) Chemosphere, 44, pp. 989-995Shishan, W., Dingjung, J., Xiaodong, O., Fen, W., Jian, S., The structure and properties of PA6/MMT nanocomposites prepared by melt compounding (2004) Polym. Eng. Sci., 44, pp. 2070-2074Sinegani, A.A.S., Emtizai, G., Shariamadari, H., Sorption and immobilization of cellulase on silicate clay minerals (2005) J. Colloid Interface Sci., 290, pp. 39-44Smith, C.R., Base exchange reactions of bentonite and salts of organic bases (1934) J. Am. Chem. Soc., 56, pp. 1561-1563Someya, Y., Shibata, M., Morphology, thermal, and mechanical properties of vinylester resin nanocomposites with various organo-modified montmorillonites (2004) Polym. Eng. Sci., 44, pp. 2041-2046Százdi, L., Pukánszky Jr., B., Földes, E., Pukánszky, B., Possible mechanism of interaction among the components in MAPP modified layered silicate PP nanocomposites (2005) Polymer, 46, pp. 801-810Tamura, K., Nakazawa, H., Intercalation of n-alkyltrimethylammonium into swelling fluoro-mica (1996) Clays Clay Miner., 44, pp. 501-505Tang, Y., Hu, Y., Song, L., Gui, Z., Chen, Z., Fan, W., Preparation and thermal stability of polypropylene/montmorillonite nanocomposites (2003) Polym. Degrad. Stab., 82, pp. 127-131Theng, B.K.G., (1974) The Chemistry of Clay-Organic Reactions, , Adam Hilger, LondonVaia, R.A., Teukolsky, R.K., Giannelis, E.P., Interlayer structure and molecular environment of alkylammonium layered silicates (1994) Chem. Mater., 6, pp. 1017-1022Valenzuela Diaz, F.R., 1994 Preparação a nível de laboratório de algumas argilas esmectíticas organofílicas. Thesis of Doctorate, Chemical Engineering, University of São PauloVianna, M.M.G.R., 2005. Desenvolvimento de argilas organofílicas visando a remediação de áreas contaminadas por componentes da gasolina. Thesis of Doctorate of Chemical Engineering, University of São PauloVolzone, C., Rinaldi, J.O., Ortiga, J., Retention of gases by hexadecyltrimethylammoniom-montmorillonite clays (2006) J. Environ. Manag., 79, pp. 247-252Vougaris, D., Petridis, D., Emulsifying effect of dimethyldioctadecylammonium-hectorita in polystyrene/poly(ethyl methacrylate) blends (2002) Polymer, 43, pp. 2213-2218Wang, S., Hu, Y., Tang, Y., Chen, Z., Fan, W., Preparation and characterization of flame retardant ABS/montmorillonite nanocomposite (2004) Appl. Clay Sci., 25, pp. 49-55Wang, L., Wang, K., Chen, L., He, C., Zhang, Y., Hydrothermal effects on the thermomechanical properties of high performance epoxy/clay nanocomposites (2006) Polym. Eng. Sci., 46, pp. 215-221Xi, Y., Ding, Z., He, H., Frost, R.L., Structure of organoclays-an x-ray diffraction and thermogravimetric analysis study (2004) J. Colloid Interface Sci., 277, pp. 116-120Xi, Y., Ding, Z., Hongping, H., Frost, Infrared spectroscopy of organoclays synthesized with the surfactant octadecyltrimethylammonium bromide (2005) Spectrochim. Acta, Part A, 61, pp. 515-525Yapar, S., Özbudak, V., Lopes, A., Effect of adsorbent of concentration to the adsorption of phenol on hexadecyl trimethyl ammonium-bentonite (2005) J. Hazard. Mater., 121, pp. 135-139Yao, H., Zhu, J., Morgan, A.B., Wilkie, C.A., Crown ether-modified clays and their polystyrene nanocomposites (2002) Polym. Eng. Sci., 42, pp. 1808-1814(2002) Organo-clay complexes and interactions, , Yariv S., and Cross H. (Eds), Marcel Dekker, Inc., New YorkYilmaz, N., Yapar, S., Adsorption properties of tetradecyl- and hexadecyl trimethylammonium bentonites (2004) Appl. Clay Sci., 27, pp. 223-228Yoshimoto, S., Osashi, F., Kameyama, T., X-ray diffraction studies of intercalation compounds prepared from aniline salts and montmorillonite by mechanical processing (2005) Sol. Sta. Comm., 136, pp. 251-256Yu, C.H., Norman, M.A., Newtont, S.Q., Miller, D.M., Teppen, B.J., Schäfer, L., Molecular dynamics simulations of the adsorption of proteins on clay minerals surfaces (2000) J. Mol. Struct., 556, pp. 95-103Yu, Y.-H., Yeh, J.-M., Liou, S.-J., Chang, Y.-P., Organo-soluble polyimide (TBAPP-ODPA)/clay nanocomposite materials with advanced anticorrosive properties prepared from solution dispersion technique (2004) Acta Mater., 52, pp. 475-486Zhang, Y.-Q., Lee, J.-H., Rhee, J.M., Rhee, K.Y., Polypropylene-clay nanocomposites prepared by in situ grafting-intercalating in melt (2004) Comp. Sci. Technol., 64, pp. 1373-1389Zhang, Y.-Q., Lee, J.-H., Jang, H.-J., Nah, C.-W., Preparing PP/clay nanocomposites using a swelling agent (2004) Composites: Part B, 35, pp. 133-138Zhang, J., Jiang, D.D., Wilkie, C.A., Polyethylene and polypropylene nanocomposites based upon an oligomerically modified clay (2005) Thermochim. Acta, 430, pp. 107-113Zhang, J., Jiang, D.D., Wilkie, C.A., Polyethylene and polypropylene nanocomposites based on a three component oligomerically-modified clay (2006) Polym. Degrad. Stab., 91, pp. 641-648Zhang, J., Jiang, D.D., Wilkie, A., Thermal and flame properties of polyethylene and polypropylene nanocomposites based on an oligomerically-modified clay (2006) Polym. Degrad. Stab., 91, pp. 298-304Zheng, X., Jiang, D.D., Wang, D., Wilkie, C.A., Flammability of styrenic polymer clay nanocomposites based on a methyl methacrylate oligomerically-modified clay (2006) Pol. Degrad. Stab., 91, pp. 289-297Zhou, X., Huang, Q., Chen, S., Yu, Z., Adsorption of the insecticidal protein of Bacillus thuringiensis on montmorillonite, kaolinite, silica, goethite and Red Soil (2005) Appl. Clay Sci., 30, pp. 87-93Zhu, J., He, H., Zhu, L., Wen, X., Deng, F., Characterization of organic phases in the interlayer of montmorillonite using FTIR and 13C NMR (2005) J. Colloid Interface Sci., 286, pp. 239-24

Knowledge Of Contraceptive Methods Among Adolescent Students [conhecimento Sobre Métodos Anticoncepcionais Por Estudantes Adolescentes]

Objective: To compare the knowledge of contraceptive methods as well as to identify factors associated with adequate knowledge among public and private school adolescents. Methods: A cross-sectional study comprising 1,594 adolescents aged between 12 and 19 years old from 13 public and five private schools in the city of São Paulo city, Brazil, was carried out from June to December 2003. Schools were randomly selected and students filled out a questionnaire about sociodemographic, reproductive and contraceptive methods. The prevalence ratios were estimated with a 95% confidence interval for each question on their knowledge of contraceptive methods and by school group. Each question correctly answered received a half score, and the cut-off value was 50% of correct answers. Statistical tests utilized were Chi-square and Wilcoxon-Gehan tests and Poisson multiple regression model Results: Of all respondents, 61% were of females in both school groups. Most students had low socioeconomic condition in public schools while they had mostly high socioeconomic condition in private schools (p<0.001). Nearly 18.6% private and 28.6% public school students were sexually active (p<0.002). In regard to their knowledge, 25.7% of public and 40.8% of private school students had a score equal to or above five. Factors associated with higher knowledge were: being female, at high school of a private school, having high socioeconomic condition, having had sexual intercourse and being older. Conclusions: Knowledge of contraceptive methods was low in both public and private school students. The study results show that both underprivileged as well as high socioeconomic adolescents need to have adequate information about family planning to improve their knowledge and change their behavior. © 2006 Faculdade de Saúde Pública da Universidade de Sao Paulo.4015764Almeida, M.C.C., Aquino, E.M.L., Gaffikin, L., Magnani, R.J., Uso de contracepção por adolescentes de escolas públicas na Bahia (2003) Rev Saúde Pública, 37 (5), pp. 566-575Azevedo, M.R.D., Educação sexual: Uma questão em aberto (2001) Adolesce̊ncia: Prevenção E Risco, pp. 129-143. , Saito MI, Leal MM, Silva LEV, editores. São Paulo: AtheneuBarros, A.J.D., Hirakata, V.N., Alternatives for logistic regression in cross-sectional studies: An empirical comparison of models that directly estimate the prevalence ratio (2003) BMC Med Res Methodol, 3, p. 21Carlini-Cotrim, B., Gazal-Carvalho, C., Gouveia, N., Comportamento de saúde entre jovens estudantes das redes pública e privada da área metropolitana do estado de São Paulo (2000) Rev Saúde Pública, 34 (6), pp. 636-645Espejo, X., Tsunechiro, M.A., Osis, M.J.D., Duarte, G.A., Bahamondese, L., Sousa, M.H., Adequação do conhecimento sobre métodos anticoncepcionais entre mulheres de Campinas, São Paulo (2003) Rev Saúde Pública, 37 (5), pp. 583-590Hair, J.F., Anderson, R.E., Tatham, R.L., Black, W.C., (1995) Multivariate Data Analysis, , 4th ed. Englewood Cliffs (NJ): Prentice-HallKleinbaum, D.G., Kupper, L.L., Morgenstern, H., (1982) Epidemiologic Research: Principles and Quantitative Methods, , New York (NY): WileyLee, E.T., (1980) Statistical Methods for Survival Data Analysis, , Belmont (CA): Lifetime LearningLeite, I.C., Rodrigues, R.N., Fonseca, M.C., Fatores associados com o comportamento sexual e reprodutivo entre adolescentes das regiões sudeste e nordeste do Brasil (2004) Cad Saúde Pública, 20 (2), pp. 474-481Moraes Filho, O.B., Albuquerque, R.M., Hardy, E., Conhecimento e uso de métodos anticoncepcionais por mulheres com aborto provocado ou espontåneo (1997) Rev IMIP, 11 (1), pp. 32-41Osis, M.J.D., Faúndes, A., Sousa, M.H., Bailey, P., Conseqüe̊ncias do uso de métodos anticoncepcionais na vida das mulheres: O caso da laqueadura tubária (1999) Cad Saúde Pública, 15 (3), pp. 521-532Schor, N., Ferreira, A.F., Machado, V.L., França, A.P., Pirotta, K.C.M., Alvarenga, A.T., Mulheres e anticoncepcção: Conhecimento e uso de métodos anticoncepcionais (2000) Cad Saúde Pública, 16 (2), pp. 377-384Warwick, D.P.E., Leninger, A.C., The sample survey: Theory and practice (1975), pp. 4-19. , New York (NY): McGraw HillIntroductio

Factors Associated With Condom Use And Knowledge About Std/aids Among Teenagers In Public And Private Schools In São Paulo, Brazil [fatores Associados Ao Uso De Preservativo Masculino E Ao Conhecimento Sobre Dst/aids Em Adolescentes De Escolas Públicas E Privadas Do Município De São Paulo, Brasil]

This study aimed to compare knowledge about STD/AIDS and identify the factors associated with adequate knowledge and consistent use of male condoms in teenagers from public and private schools in the city of São Paulo, Brazil. We selected 1,594 adolescents ranging 12 to 19 years of age in 13 public schools and 5 private schools to complete a questionnaire on knowledge of STD/AIDS and use of male condoms. Prevalence ratios were computed with a 95% confidence interval. The score on STD knowledge used a cutoff point corresponding to 50% of correct answers. Statistical tests were chisquare and Poisson multiple regression. Consistent use of male condoms was 60% in private and 57.1% in public schools (p > 0.05) and was associated with male gender and lower socioeconomic status. Female gender, higher schooling, enrolment in private school, Caucasian race, and being single were associated with higher knowledge of STDs. Teenagers from public and private schools have adequate knowledge of STD prevention, however this does not include the adoption of effective prevention. Educational programs and STD/AIDS awareness-raising should be expanded in order to minimize vulnerability.222315323Braverman, P.K., Sexually transmitted diseases in adolescents (2000) Med Clin North Am, 84, pp. 869-889Kaplan, D.W., Feinstein, R.A., Fisher, M.M., Klein, J.D., Olmedo, L.F., Rome, E.S., Condom use by adolescents (2001) Pediatrics, 107, pp. 1463-1469Dollabetta, G., Lyn, M., Laga, M., Islam, M., DST: Impacto global do problema e desafios para o controle (1997) Controle Das Doenças Sexualmente Transmissíveis. Manual de Planejamento e Coordenação de Programas, pp. 1-22. , Dollabetta G, Laga M, Lamptey P, organizadores. São Paulo: Associação Saúde da Família/Editora Te CoráShrier, L.A., Goodman, E., Emans, S.J., Partner condom use among adolescent girls with sexually transmitted diseases (1999) J Adolesc Health, 24, pp. 357-361Shrier, L.A., Sexually transmitted diseases in adolescents: Biologic, cognitive, psychologic, behavioral, and social issues (2004) Adolesc Med Clin, 15, pp. 215-234Clark, L.R., Jackson, M., Allen-Taylor, L., Adolescent knowledge about sexually transmitted diseases (2002) Sex Transm Dis, 29, pp. 436-443Boekeloo, B.O., Howard, D.E., Oral sexual experience among young adolescents receiving general health examinations (2002) Am J Health Behav, 26, pp. 306-314(1997) Pesquisa Nacional Sobre Demografia e Saúde, Brasil, 1996, , Rio de Janeiro: Sociedade Civil Bem-Estar Familiar no BrasilA Voz Dos Adolescentes, , http://www.unicef.org.brAlmeida, M.C.C., Aquino, E.M.L., Gaffikin, L., Magnani, R.J., Uso de contracepção por adolescentes de escolas públicas na Bahia (2003) Rev Saúde Pública, 37, pp. 566-575Carlini-Cotrim, B., Gazal-Carvalho, C., Gouveia, N., Comportamento de saúde entre jovens estudantes das redes pública e privada da área metropolitana do Estado de São Paulo (2000) Rev Saúde Pública, 34, pp. 626-645Warwick, D.P., Lininger, C.A., (1975) The Sample Survey: Theory and Practice, , New York: McGraw-HillCenso Escolar, , http://www.inep.gov.br/basica/censo/Melo, M.B., (1999) Conseqüências Da Orientação Sexual Na Escola: Uma Avaliação, , Campinas: Centro de Pesquisa Materno-infantis de CampinasRelatório de PesquisaHair, J.F., Anderson, R.E., Tatham, R.L., Black, W.C., (1995) Multivariate Data Analysis. 4th Ed., , New Jersey: Prentice-HallAlmeida, P.M., Wickerhauser, H., (1991) O Critério ABA/ABIPEME Em Busca de Uma Atualização, , São Paulo: Associação Brasileira de Anunciantes/Associação Brasileira de Institutos de Pesquisa de MercadoLee, E.T., (1980) Statistical Methods for Survival Data Analysis, , Belmont: Lifetime Learning PublicationsKleinbaum, D.G., Kupper, L.L., Morgenstern, H., (1982) Epidemiologic Research, , New York: John Wiley & SonsEspejo, X., Tsunechiro, M.A., Osis, M.J.D., Duarte, G.A., Bahamondes, L., Sousa, M.H., Adequação do conhecimento sobre métodos anticoncepcionais entre mulheres de Campinas, São Paulo (2003) Rev Saúde Pública, 37, pp. 583-590Barros, A.J.D., Hirakata, V.N., Alternatives for logistic regression in cross-sectional studies: An empirical comparison of models that directly estimate the prevalence ratio (2003) BMC Med Res Methodol, 3, p. 21Leite, I.C., Rodrigues, R.N., Fonseca, M.C., Fatores associados com o comportamento sexual e reprodutivo entre adolescentes das regiões Sudeste e Nordeste do Brasil (2004) Cad Saúde Pública, 20, pp. 474-481Berquó, E., Como, quando e com quem se casam os jovens brasileiros (1998) Jovens Acontecendo Na Trilha Das Políticas Públicas, pp. 93-108. , Comissão Nacional de População e Desenvolvimento, organizador. Brasília: Comissão Nacional de População e DesenvolvimentoAbramovay, M., Castro, M.G., Silva, L.B., (2004) Juventudes e Sexualidade, , Brasília: Edições UNESCO BrasilMagnani, R.J., Seiber, E.E., Gutierrez, E.Z., Vereau, D., Correlates of sexual activity and condom use among secondary-school students in urban Peru (2001) Stud Fam Plann, 32, pp. 53-65Sonestein, F.L., Ku, L.C., Lindenberg, L.D., Turner, C.F., Pleck, J.H., Changes in sexual behavior and condom use among teenage males: 1988 to 1995 (1998) Am J Public Health, 88, pp. 956-959Jiménez, A.L., Gotlieb, S.L.D., Hardy, E., Zaneveld, L.J.D., Prevenção de doenças sexualmente transmissíveis em mulheres: Associação com variáveis sócioeconômicas e demográficas (2001) Cad Saúde Pública, 17, pp. 55-62Santos, V.L., Santos, C.L., Adolescentes, jovens e Aids no Brasil (1999) Cadernos Juventude, Saúde e Desenvolvimento, 1, pp. 213-222. , Schor N, Mota MSFT, Castelo V, organizadores. Brasília: Secretaria de Políticas de Saúde, Ministério da Saúd