Relationship Between Pore Structure And 1h-nmr Relaxation Times In Tio2/poly(dimethylsiloxane) And Caco3/poly(dimethylsiloxane) Composite Powders

Titanium(IV) oxide/polydimethylsiloxane (PDMS) and calcium carbonate/PDMS composite powders were obtained by adsorption of the polymer from a chloroform solution onto the inorganic particles followed by a thermal treatment. The composites were characterized by 1H-NMR relaxation and porosimetry. The composites present shorter spin-lattice (T1) and spin-spin (T2) proton relaxation times than silica-reinforced PDMS, and the activation energies for the motions that cause spin-lattice relaxation are 5.8, 4.9, and 0.72 kJ mol-1 for TiO2/PDMS, CaCO3/PDMS, and neat PDMS, respectively, revealing the greater rigidity of the polymer chains within the composite. Spin-spin relaxation (T2) measurements of the composites showed a major component with a shorter T2 and a minor component with a longer T2. The intensity ratio of these two components is very close to the ratio between the amount of polymer that remains between the particles and that penetrating the particle pores as measured by Hg intrusion porosimetry. The shorter T2 component was thus assigned to polymer interspersed among the particles, while the longer T2 component was assigned to polymer within the particle pores.741126602666Mosbach, K., Andersson, L., (1977) Angew Makromol Chem, 57, p. 225Nakatsuka, T., Kawasaki, H., Yamashita, K., (1981) J Colloid Interface Sci, 82, p. 298Ono, T., (1986) Org Coatings, 18, p. 279Eden, J., Trksak, R., Williams, R., U.S. Pat. 4,755,397 A, 1988Tanaka, M., Hosogai, K., Yamada, T., (1988) Shikizai Kyokaishi, 61, p. 543Ono, T., (1986) Org Coatings, 18, p. 279Solc, J., Eur. Pat. Applic. 0 054 832 A2, 1981Maslosh, V.Z., Popov, A.F., Pashchenko, V.L., Kudyukov, Y.P., Moroz, V.A., BukhaN'Ko, A.I., Russ. Pat. 1652324 A1, 1991Templeton-Knight, R.L., (1990) J Oil Colour Chem Assoc, 73, p. 459Templeton-Knight, R.L., (1990) Chem ind, 16, p. 512Botter W., Jr., Soares, R.F., Galembeck, F., (1992) J Adhesion Sci Technol, 6, p. 781Soares, R.F., Leite, C.A.P., Botter W., Jr., Galembeck, F., (1996) J Appl Polym Sci, 60, p. 2001Ballistreri, A., Garozzo, D., Montaudo, G., (1984) Macromolecules, 17, p. 1312Allen, K.W., (1992) J Adhesion Sci Technol, 6, p. 23Zhang, S., Schindler, B., Nicholson, G., Bayer, E., (1995) J High Resolut Chromatogr, 18, p. 579Grundemeier, G., Matheisen, E., Stratmann, M., (1996) J Adhesion Sci Technol, 10, p. 573Plueddemann, E.P., (1982) Silane Coupling Agents, , Plenum Press: New YorkThomas, T.H., Kendrick, T.C., (1969) J Polym Sci, 7, p. 537Plueddemann, E.P., (1985) Encyclopedia of Polymer Science and Engineering, 4, pp. 204-308. , Wiley-Interscience: New YorkAbragam, A., (1961) The Principles of Nuclear Magnetism, , Clarendon Press: Oxford, U.KCohen-Addad, J.P., Doruard, M., Herz, H., (1982) J Chem Phys, 76, p. 2744Cohen-Addad, J.P., (1974) J Chem Phys, 60, p. 2440Kimmich, R., (1982) Colloid Polym Sci, 260, p. 911Loy, D.A., Mason, G.M., Maugher, B.M., Myers, S.A., Assinik, R.A., Shea, K.J., (1996) Chem Mater, 8, p. 656Soares, R.F.M., (1997), Sc. Thesis, University of Campinas, Campinas, SpainKendrick, T.C., Parbhoo, B., White, J.W., (1989) In the Chemistry of Organosilicon Compounds, 2, p. 1335. , Patai, S.Rappoport, Z., Eds.Wiley: Chichester, U.KDiré, S., Babonneau, F., Carturan, G., Livage, J., (1992) J Non-Cryst Solids, 147-148, p. 62Babonneau, F., Maquet, J., Diré, S., (1993) Polym Prepr, 34, p. 246Garrido, L., Mark, J.E., Sun, C.C., Ackerman, J.L., Chang, C., (1991) Macromolecules, 24, p. 4067Powles, J.G., Hartland, A., Kail, J.A.E., (1961) J Polym Sci, 55, p. 361Cuniberti, C., (1970) J Polym Sci Polym Phys Ed, 8, p. 205

A Prospective Clinical Study on the Use of Reverse Transcription-Polymerase Chain Reaction for the Early Diagnosis of Dengue Fever

Laboratory testing for dengue virus is used to confirm the diagnosis of dengue virus infection and to differentiate dengue from other febrile tropical illnesses. There are few data on the clinical use of reverse transcription-polymerase chain reaction (RT-PCR) for diagnosis of dengue virus infection. We prospectively evaluated 121 consecutive patients with possible dengue who had samples submitted for RT-PCR, IgM serology, and virus culture. Results were compared with the final discharge diagnosis. Semi-nested RT-PCR was performed using genus- and serotype-specific NS3 consensus primers. Results of 112 patients were available for the final analysis. The RT-PCR was positive in 40 of 62 patients with dengue. Patients who were RT-PCR-positive alone showed a mean of 4.4 days to RT-PCR positivity compared with 5.9 days in patients who were RT-PCR-negative and IgM serology-positive (P = 0.03, Mann-Whitney U-test). The sensitivity, specificity, negative predictive value, and positive predictive value were 70, 100, 84, and 100%, respectively, for samples analyzed within 5 days of illness onset. The RT-PCR also provided epidemiological data regarding the prevailing dengue virus serotypes: 25 with Den-2, eight with Den-3, and seven with Den-1 infection. We propose an algorithm of dengue testing that uses RT-PCR within 5 days of illness onset, whereas IgM capture enzyme-linked immunosorbent assay is preferred for those presenting later