Voltammetric Properties of Nickel Hexacyanoferrate (III) Obtained on the Titanium (IV) Silsesquioxane Occluded into the H-FAU Zeolite for Detection of Sulfite

Silicon - A composite prepared from titanium (IV) silsesquioxane and phosphoric acid (TTiP) was prepared and occluded into the H-FAU zeolite (ZTTiP). The material was chemically modified with...     

Biological nitrogen fixation in field-grown sorghum under different edaphoclimatic conditions is confirmed by N isotopic signatures

Nutrient Cycling in Agroecosystems - The association between sorghum and N2-fixing bacteria has been assessed only under limited conditions. We investigated biological nitrogen fixation (BNF) in...     

TiO2 as a gas sensor: The novel carbon structures and noble metals as new elements for enhancing sensitivity – A review

The development of highly selective, stable, and sensitive materials for the various gas emissions is a challenging task concerning the numerous applications: environmental control, security systems, energy, and, more recently, biological monitoring. One of the major challenges to reach this activity's requirements is developing nanostructured functional and smart materials that can selectively detect and monitor the gases at high temperatures. The semiconductor materials based on metallic oxides have gained increasing attention within this scenario, especially titanium dioxide (TiO₂), due to their excellent properties. The literature presents multiple sensors based on TiO₂ nanoparticles to detect various gases: CO, ethanol, benzene, toluene, NO₂, O₂, CO, SO₂, NO_x, NH₃, Cl₂, H₂S, alkanes, among others. This review initially explores some aspects of TiO₂ and its properties regarding the sensor sensitivity's influence. Then, the insertion of noble metals (Ag, Pt, Au, and Ru) and carbon structures (graphene, carbon nanotube, and other carbon forms) was also explored in the search to improve the TiO₂ capacity as a gas sensor. This review focuses on the most significant achievements related to TiO₂ and TiO₂ combined with carbon structures or noble metals for gas sensor applications. Several studies were presented, highlighting the synthesis methods employed, the sensor response/recovery times, and some detection mechanisms after the carbon and noble metal insertion. Finally, the influence of a triple combination between TiO₂-carbon-metal was also explored.     

Voltammetric Detection of Nitrite Throught a Chemically Modified (5-Amino-1,3,4-Thiadiazolyl-2-Thiol) Propyl Silica Gel

Silicon - This study describes an organofunctionalization of 3-chloropropyl silica gel (SG) with 5-amino-1,3,4-thiadiazolyl-2-thiol, and was characterized by spectroscopic techniques as infrared...     

Performance of a reversible heat pump/organic Rankine cycle unit coupled with a passive house to get a positive energy building

This paper presents an innovative technology that can be used to deliver more renewable electricity production than the total electrical consumption of a building while covering the heat demand on a yearly basis. The technology concept uses a heat pump (HP), slightly modified to revert its cycle and generate electricity, coupled to a solar thermal collector roof. This reversible HP/organic Rankine cycle unit presents three operating modes: direct heating, HP and organic Rankine cycle. This work focuses on describing the dynamic model of the multi-component system followed by a techno-economic analysis of the system under different operational conditions. Sensitivity studies include: building envelope, climate, appliances, lighting and heat demand profiles. It is concluded that the HP/ORC unit can turn a single-family house into a PEB under certain weather conditions (electrical production of 3012?kWh/year and total electrical consumption of 2318?kWh/year) with a 138.8?m² solar roof in Denmark.     

Evaluation of Nickel Neurotoxicity and High Sorption through a Hybrid Yeast / Silsesquioxane Material

Silicon - The presence of heavy metals in water is one of the major concerns in the public health area. So, the characterization of inorganic compounds toxicity and their detection, speciation and...     

A Comparative Voltammetric Study of a Chemically Modified Octa(3-Aminopropyl)Octasilsesquioxane and DAB-AM-16 Dendrimer Supported on the Silica Gel Surface for Dipyrone Detection

Silicon - Octa(3-aminopropyl)octasilsesquioxane and DAB-AM-16 dendrimer, due to their specific chemical and physical properties, give wide application in various fields of science. Because they...     

Dynamic mechanical properties and morphological structure of PS/EPDM blends prepared by in situ‐polymerization of styrene

PS/EPDM blends prepared by in situ‐polymerization of styrene in the presence of EPDM are immiscible and show two phases. Furthermore, the dynamic mechanical behavior of injected specimens is quite different from that of noninjected blends. This is attributed to the differences in morphology before and after injection molding. The morphology of the noninjected blends consists of PS spherical domains covered by a thin layer of EPDM, whereas the injected blends show elastomeric dispersed phase morphology in a rigid matrix. SEM analysis was important to elucidate the changes in the dynamic mechanical behavior of PS/EPDM blends, but TEM analysis is more precise for morphological characterization and yielded the real average diameter of EPDM particles. Comparing the average diameters for the PS/EPDM blends obtained from SEM and TEM analyses, the diameters obtained from the SEM analysis are wider than those of TEM which is due to the solvent extraction effect on the blend morphology. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effect of in situ polymerization conditions of methyl methacrylate on the structural and morphological properties of poly(methyl methacrylate)/poly(acrylonitrile‐g‐(ethylene‐co‐propylene‐co‐diene)‐g‐styrene) PMMA/AES Blends

In this study, the structural and morphological properties of poly(methyl methacrylate)/poly(acrylonitrile‐g‐(ethylene‐co‐propylene‐co‐diene‐g‐styrene) (PMMA‐AES) blends were investigated with emphasis on the influence of the in situ polymerization conditions of methyl methacrylate. PMMA‐AES blends were obtained by in situ polymerization, varying the solvent (chloroform or toluene) and polymerization conditions: method A—no stirring and air atmosphere; method B—stirring and N₂ atmosphere. The blends were characterized by infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and dynamic mechanical analysis (DMA). The results showed that the PMMA‐AES blends are immiscible and present complex morphologies. This morphology shows an elastomeric dispersed phase in a glassy matrix, with inclusion of the matrix in the elastomer domains, suggesting core shell or salami morphology. The occlusion of the glassy phase within the elastomeric domains can be due to the formation of graft copolymer and/or phase inversion during polymerization. However, this morphology is affected by the polymerization conditions (stirring and air or N₂ atmosphere) and by the solvent used. The selective extraction of the blends' components and infrared spectroscopy showed that crosslinked and/or grafting reactions occur on the elastomer chains during MMA polymerization. The glass transition of the elastomer phase is influenced by morphology, crosslinking, and grafting degree and, therefore, T_g depends on the polymerization conditions. On the other hand, the behavior of T_g of the glassy phase with blend composition suggests miscibility or partial miscibility for the SAN phase of AES and PMMA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012