Dynamic Scaling and Growth Kinetics of 3-Glycidoxypropyltrimethoxysilane-Derived Organic/Silica Hybrids

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Temperature Effect on the Structure and Formation Kinetics of Vinyltriethoxysilane-Derived Organic/Silica Hybrids

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Structure and aggregation kinetics of vinyltriethoxysilane-derived organic/silica hybrids

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Persistence Length, Mass Fractal, and Branching in the Aggregating of Vinyltriethoxysilane-Derived Organic/Silica Hybrids

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Fabrication of coaxial TiO2/Sb2S3 nanowire hybrids for efficient nanostructured organic- inorganic thin film photovoltaics

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Aluminoxane-epoxi-siloxane hybrids waveguides

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Optical Fiber Relative Humidity Sensor Based on a FBG with a Di-Ureasil Coating

In this work we proposed a relative humidity (RH) sensor based on a Bragg grating written in an optical fiber, associated with a coating of organo-silica hybrid material prepared by the sol-gel method. The organo-silica-based coating has a strong adhesion to the optical fiber and its expansion is reversibly affected by the change in the RH values (15.0-95.0%) of the surrounding environment, allowing an increased sensitivity (22.2 pm/%RH) and durability due to the presence of a siliceous-based inorganic component. The developed sensor was tested in a real structure health monitoring essay, in which the RH inside two concrete blocks with different porosity values was measured over 1 year. The results demonstrated the potential of the proposed optical sensor in the monitoring of civil engineering structures.

Thermoregulation in colonies of africanized and hybrids with Caucasian, Italian and Carniolan Apis mellifera honey bees

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Response of cattleya hybrids for Fusarium oxysporum f. sp. cattleyae Foster

The Cattleya genus has a great importance in the flower agro-business market. Fusarium wilts, caused by Fusarium oxysporum f. sp. cattleyae, is considered one of the main factors of decline and death of plants of this genus. Using seven hybrids (intra and intergenerics) of Cattleya, tests of resistance and susceptibility to F. oxysporum were performed in conditions of greenhouse for 12 months, using, as evaluation criterion, a scale of the disease severity ranging from one (resistant) to eight (highly susceptible). High susceptibility to the fungus by Cattleya Nobile's Wax Toy, Cattleya Orquidacea's Mister Fast intrageneric hybrids and Potinara Orquidacea's Havana Brown intergeneric hybrid, related to Brassocattleya Orquidacea's Melody intergeneric hybrid, high resistance to the pathogens was observed.

ROOT-GROWTH AND MINERAL-NUTRITION OF CORN HYBRIDS AS AFFECTED BY PHOSPHORUS AND LIME

The effects of triple superphosphate (TS) and liming on macronutrient accumulation and root growth of Pioneer 3072 and Cargill 505 com hybrids were studied. Com plants were grown up to 30 days in pots with 7 L of a dark red Latosol sandy loam (Haplortox). Lime was applied to raise base saturation to 30, 50, and 70%, in two levels of phosphorus (P) fertilization with TS (0 and 200 ppm P). There was an increase in root surface due to lime only in pots without TS, with no effects on plant growth or nutrition. Both com hybrids responded to P fertilization, but Pioneer yielded more dry matter than Cargill. The roots of Cargill were thicker and, when in TS presence, were longer and had a larger surface than Pioneer. There was an increase in macronutrient uptake in the P fertilized pots. Pioneer required more nutrients and showed a higher efficiency in acquiring and utilizing the nutrients from the soil. A higher response of Pioneer in dry matter and nutrient acquisition was more related to the physiological efficiency than to root morphology.

Planar and UV written channel optical waveguides prepared with siloxane poly(oxyethylene)-zirconia organic-inorganic hybrids. Structure and optical properties

Organic-inorganic hybrids were prepared using ureapropyltriethoxysilane, methacryloxypropyltrimethoxysilane and acrylic acid modified zirconium(IV) n-propoxide precursors and were characterized by small angle X-ray scattering, X-ray diffraction and photoluminescence spectroscopy. The results indicate an effective interaction between the zirconium-based nanoparticles and the siliceous nanodomains that induces changes in the hybrids' emission features. Planar waveguides were obtained by spin-coating of the prepared sols on sodalime and silica substrates. Refractive index, thickness, number of propagating modes, and attenuation coefficient were measured at 543.5, 632.8 and 1550 nm by the prism coupling technique. The synergism between the two hybrid precursors resulted in monomode planar waveguides with low losses in the infrared ( from 0.6-1.1 dB cm(-1)) which also support a number of propagating modes in the visible ( losses from 0.4-1.5 dB cm(-1)). Channel waveguides were also obtained by UV photopatterning using amplitude or phase masks and propagating modes were observed at 1550 nm.

Structural modelling of Eu3+-based siloxane-poly( oxyethylene) nanohybrids

The modelling of the local structure of sol-gel derived Eu3+-based organic/inorganic hybrids is reported, based on Small-Angle X-ray Scattering (SAXS), photoluminescence and mid-infrared spectroscopy. The hybrid matrix of these organically modified silicates, classed as di-ureasils and termed U(2000) and U(600), is formed by poly( oxyethylene) (POE) chains of variable length grafted to siloxane domains by means of urea cross-linkages. Europium triflate, Eu(CF3SO3)(3), was incorporated in the two di-ureasil matrices with compositions 400 greater than or equal ton greater than or equal to 10, n is the molar ratio of ether oxygens per Eu3+. The SAXS data for undoped hybrids (n=infinity) show the presence of a well-defined peak attributed to the existence of a liquid-like spatial correlation of siloxane rich domains embedded in the polymer matrix and located at the ends of the organic segments. The obtained siloxane particle gyration radius Rg(1) is around 5 Angstrom (error within 10%), whereas the interparticle distance d is 25 +/-2 Angstrom and 40 +/-2 Angstrom, for U(600) and U(2000), respectively. For the Eu3+-based nanocomposites the formation of a two-level hierarchical local structure is discerned. The primary level is constituted by strongly spatially correlated siloxane particles of gyration radius Rg(1) (4-6 and 3-8 Angstrom, errors within 5%, for U(600())n Eu(CF3SO3)(3), 200 greater than or equal ton greater than or equal to 40, and U(2000)(n)Eu(CF3SO3)(3), 400 greater than or equal ton greater than or equal to 40, respectively) forming large clusters of gyration radius Rg(2) (approximate to 75 +/- 10 Angstrom). The local coordination of Eu3+ in both di-ureasil series is described combining the SAXS, photoluminescence and mid-infrared results. In the di-ureasils containing long polymer chains, U(2000)(n)Eu(CF3SO3)(3), the cations interact exclusively with the carbonyl oxygens atoms of the urea bridges at the siloxane-POE interface. In the hybrids containing shorter chains, U(600)(n)Eu(CF3SO3)(3) with n ranging from 200 to 60, the Eu3+ ions interact solely with the ether-type oxygens of the polymer chains. Nevertheless, in this latter family of hybrids a distinct Eu3+ local site environment involving the urea cross-linkages is detected when the europium content is increased up to n=40.

A CLUSTER MODEL FOR HYBRIDS

A model for describing hybrid spectroscopy similar to the diquark model for baryons is presented. Mass and r.m.s. radii are calculated and compared with experimental results.