Orientador: Eloi Dezan Junior / Banca: Francine Benetti / Banca: Renato de Toledo Leonardi / Resumo: Além da atividade antimicrobiana e biocompatibilidade de um curativo de demora, é oportuno que ele tenha também a capacidade de estimular a biomineralização e reparo dos tecidos periapicais. O objetivo deste estudo foi avaliar a resposta inflamatória, a capacidade de induzir biomineralização e reparo tecidual em tecido subcutâneo de ratos, causada pelas pastas de iodofórmio e hidróxido de cálcio. Foram utilizados 18 ratos Wistar albinos (n=6), que receberam implantes subcutâneos de tubos de polietileno com os seguintes materiais: hidróxido de cálcio + propilenoglicol (1:1) [Ca(OH)2+P], hidróxido de cálcio + propilenoglicol + iodofórmio (2:1:1) [Ca(OH)2+P+Iodo], iodofórmio + Carbowax (5:1) [Iodo+Carbow] and Carbowax [Carbow]. Tubos vazios extras foram utilizados como grupo controle. Após 7, 15 e 30 dias, os implantes foram removidos conjuntamente com tecido circundante. Foram utilizadas as colorações de hematoxilina-eosina (HE), Von Kossa (VK), técnica de luz polarizada (LP) e Picrosirius red (PSR). Para HE foram utilizados os scores de 0, poucas células inflamatórias; 1, menos de 25 células inflamatórias - reação leve; 2, entre 25 e 125 células inflamatórias - reação moderada; e 3, 125 ou mais células inflamatórias - reação severa (400x). A cápsula fibrosa foi considerada fina quando menor que 150 μm e espessa quando maior que 150 μm. A capacidade de mineralização foi analisada como positivo ou negativo com VK e como presente ou ausente sob LP. Para PSR as fibras imaturas apa... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The antimicrobial activity and biocompatibility of a root canal dressing are important requirement, but it is also interesting that it has the ability of stimulate biomineralization and repair of the periapical tissues. The objective of this study was to evaluate the inflammatory response, biomineralization and tissue repair induction in subcutaneous tissue of rats caused by iodoform and calcium hydroxide. Eighteen Wistar rats (n=6) received subcutaneous implants with iodoform and calcium hydroxide pastes. Extra empty tubes were used as control group. After 7, 15 and 30 days, the implants were removed with surrounding tissue. Kruskal-Wallis test was used with a significance level of 5%. At 7 days, all groups excluding carbowax, showed moderate inflammatory reaction and thick fibrous capsule. At 15 days, all groups excluding control decrease their fibrous capsule thickness. At 30 days all groups presented mild reaction and fine fibrous capsule. Only the groups containing calcium hydroxide presented mineralized tissue in all periods analyzed. At 7 days all groups showed a higher proportion of immature fibers. At 15 days, only [Ca(OH)2 + P] and [Carbow] groups increased their proportion of mature / immature fibers. At 30 days, the [Ca(OH)2 + P] group was the only that presented prevalence of mature collagen fibers, with significant difference (p <0.05). The null hypothesis was partially rejected. All groups showed biocompatibility. Only the groups containing Ca(OH)2 induced the ... (Complete abstract click electronic access below) / Mestre

The fate and mobility of boric acid in the environment is largely controlled by adsorption reactions with soil organic matter and soil minerals to form surface complexes (Marzadori et al., 1991; Su and Suarez, 1995; Yermiyahu et al., 1995; Peak et al., 2002). The effects of humic acid (HA) and dissolved CO2 on boric acid adsorption on amorphous (am)-Al(OH)3 were investigated as their influence on sorption is potentially important. Although a model system was used in the studies, the findings should be generally useful to better understand the mobility and bioavailability of boric acid in the soil ecosystems.<p>In this dissertation, boric acid adsorption on pure am-Al(OH)3 and 5% w/w HA coated am-Al(OH)3 were investigated both as a function of pH (4.5 11) and initial boric acid concentration (0 4.5 mmol L-1). Batch adsorption isotherm experiments were also conducted with samples exposed to atmospheric CO2 and anaerobic (N2) conditions to examine the effects of dissolved CO2 on boric acid adsorption. Both the pH envelope and the adsorption isotherm experiments showed that the HA coating on am-Al(OH)3 and the presence of dissolved CO2 decreased boric acid adsorption. <p>Raman spectroscopy and boron (B) K-edge X-ray Absorption Near Edge Structure (XANES) spectroscopy were used to investigate the coordination of boric acid adsorbed at mineral/water interfaces. The Raman spectroscopy was less successful than expected as there were difficulties in identifying B bands in the 5% w/w HA coated am-Al(OH)3 samples.<p>The B K-edge XANES spectroscopy yielded better results. The XANES spectra of boric acid adsorption samples showed that both trigonal BO3 and tetrahedral BO4 coordinated complexes are present on the pure and HA coated mineral surfaces. At pH 7.0 and 9.2, the adsorption of boric acid on am-Al(OH)3 is predominantly inner-sphere trigonal complexes; with minor amounts of inner-sphere tetrahedral complexes. Both macroscopic and spectroscopic experiments revealed that the combination of HA coating on am-Al(OH)3 and dissolved CO2 decreased boric acid adsorption compared to adsorption on pure am-Al(OH)3.<p>The discoveries in this dissertation contribute significantly in understanding the effects of HA and dissolved CO2 has on boric acid adsorption in the environment. Since B speciation and the stability of am-Al(OH)3 mineral and HA changes with pH, the bioavailability of B is expected to change as well with pH. The adsorption on boric acid on am-Al(OH)3 and/or HA coated am-Al(OH)3 is expected to decrease the amount of boric acid available to plants. Therefore the nutrient management regimen will have to be modified for soils that are high in natural organic matter, carbonate and/or aluminum hydroxyl species.

The fate and mobility of boric acid in the environment is largely controlled by adsorption reactions with soil organic matter and soil minerals to form surface complexes (Marzadori et al., 1991; Su and Suarez, 1995; Yermiyahu et al., 1995; Peak et al., 2002). The effects of humic acid (HA) and dissolved CO2 on boric acid adsorption on amorphous (am)-Al(OH)3 were investigated as their influence on sorption is potentially important. Although a model system was used in the studies, the findings should be generally useful to better understand the mobility and bioavailability of boric acid in the soil ecosystems.<p>In this dissertation, boric acid adsorption on pure am-Al(OH)3 and 5% w/w HA coated am-Al(OH)3 were investigated both as a function of pH (4.5 11) and initial boric acid concentration (0 4.5 mmol L-1). Batch adsorption isotherm experiments were also conducted with samples exposed to atmospheric CO2 and anaerobic (N2) conditions to examine the effects of dissolved CO2 on boric acid adsorption. Both the pH envelope and the adsorption isotherm experiments showed that the HA coating on am-Al(OH)3 and the presence of dissolved CO2 decreased boric acid adsorption. <p>Raman spectroscopy and boron (B) K-edge X-ray Absorption Near Edge Structure (XANES) spectroscopy were used to investigate the coordination of boric acid adsorbed at mineral/water interfaces. The Raman spectroscopy was less successful than expected as there were difficulties in identifying B bands in the 5% w/w HA coated am-Al(OH)3 samples.<p>The B K-edge XANES spectroscopy yielded better results. The XANES spectra of boric acid adsorption samples showed that both trigonal BO3 and tetrahedral BO4 coordinated complexes are present on the pure and HA coated mineral surfaces. At pH 7.0 and 9.2, the adsorption of boric acid on am-Al(OH)3 is predominantly inner-sphere trigonal complexes; with minor amounts of inner-sphere tetrahedral complexes. Both macroscopic and spectroscopic experiments revealed that the combination of HA coating on am-Al(OH)3 and dissolved CO2 decreased boric acid adsorption compared to adsorption on pure am-Al(OH)3.<p>The discoveries in this dissertation contribute significantly in understanding the effects of HA and dissolved CO2 has on boric acid adsorption in the environment. Since B speciation and the stability of am-Al(OH)3 mineral and HA changes with pH, the bioavailability of B is expected to change as well with pH. The adsorption on boric acid on am-Al(OH)3 and/or HA coated am-Al(OH)3 is expected to decrease the amount of boric acid available to plants. Therefore the nutrient management regimen will have to be modified for soils that are high in natural organic matter, carbonate and/or aluminum hydroxyl species.

The broad objective of the study was to gain further knowledge of the reaction rates and mechanisms by which carbohydrates, particularly 3(l-4) glucans, are transformed and degraded in aqueous alkaline solutions. While the isomerization, epimerization, and degradation of carbohydrates has been extensively studied and reviewed, there are practically no kinetic data available on these important reactions due apparently to a lack of reasonable procedures for assay of the reaction systems. Because of the important theoretical, physiological, and industrial implications of these reactions, it appeared useful to have kinetic data on them and concomitantly thus to develop a method for obtaining such data. The specific problem selected for study from this broad area was the measurement of reaction rates prevailing in the homogeneous system: cellobiose-l molar sodium hydroxide-water at 22°C. and to derive-the related rate constants from the reaction rate expressions and then to assess current understanding of these reactions in light of the kinetic data obtained.

No description available.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1966. / Includes bibliographical references (p. 93-96).

This work presents the first alkaline redox flow battery (a-RFB) based on the coordination chemistry of cobalt(III/II) and iron(III/II) with amino-alcohol ligands in concentrated NaOH([subscript aq]). The a-RFB was developed by carrying out systematic structural and electrochemical characterizations of various redox-active coordination compounds to find the most suitable candidates for electrochemical energy storage. In the characterization studies, particular attention was given to the redox couple Fe(III/II)- TEA, where TEA = triethanolamine, because of its importance in the fields of supramolecular chemistry, magnetic memory films, and electrochemical energy storage. The structures of Fe(III)-TEA in the solid state and in alkaline solution are reported for the first time. Moreover, experimental evidence is presented for the existence of an EC reaction in the heterogeneous reduction of Fe(III/II)-TEA in concentrated base. Furthermore, experiments were carried out to study the reactivity of Fe(II)-TEA with O2. This is important because O2 reacts spontaneously with Fe(II)-TEA to produce hydrogen peroxide, decreasing the charging-discharging capacity of the a-RFB. The reduction of oxygen by Fe(II)-TEA in concentrated base was studied by UV-Vis spectroscopy and coulometric titrations. Additionally, a new method for the quick identification of redox couples with slow EC reactions, k[subscript f] < 0.1 s-1, is presented. The new method is based on scanning electrochemical microscopy (SECM) and consists of creating a thin-layer cell between the tip and substrate electrode. During analysis of a redox couple, the tip reports a current transient proportional to the decaying concentration of the product of the E reaction, from which an apparent forward rate constant for the C reaction can be determined. This method was designed for the field of RFB research, where the identification of redox couples with no EC reactions is necessary to ensure that a battery can run for thousands of cycles. Lastly, surface oxidation of polycrystalline Ir ultramicroelectrodes was studied by the surface interrogation mode of SECM (SI-SECM), using Fe(II)-TEA as the titrant. This was done to demonstrate the existence of hydrous oxides of Ir(IV) and Ir(V) prior to the onset of oxygen evolution in concentrated base. Numerical simulations were carried out using commercial software and were used to validate the experimental results reported in this work. / text

No description available.

Gas phase chemiluminescence nitrogen specific detector (CLND)is used for the direct analysis of underivatized nitrogen-containing components such as alkylamines that can not be detected by the so called universal HPLC detector, the UV detector. However, alkali metal hydroxides can not be used as mobile phase constituents with the CLND because they form non volatile particulate combustion products that foul the detector. Therefore, trimethylsulfonium hydroxide (TMSOH) has been selected as a strong base for use with the CLND, because its combustion products, CO2, H2O and SxOy are volatile. An alkali-stable zirconia-based column was used and coupled to the CLND. Zirconia-based columns are mechanically and hydrolytically more stable than silica-based columns, which have a working pH range from 3 to 8 only. Zirconia-based columns can be used at a pH from 1 to 14 and can be used at temperatures up to 200˚C. The separation of amines was carried out at high pH values where the amino groups were deprotonated. Primary, secondary, tertiary and quaternary amines were separated using a pH=13.7 mobile phase that contained only TMSOH, methanol and water. Good peak shapes were observed for all, except n-alkylamines and samples that contained both amino groups and alcohol groups.

High density polyethylene (HDPE) is a widely used plastic but it is also a combustible material. One way of reducing flammability is to add fillers, such as magnesium hydroxide (Mg(OH)2). However, this has a deleterious effect on the mechanical properties of composites. It has been found that one possible method of restoring mechanical properties is to modifY the filler particles with coating agents, such as stearic acid. In the present work, this idea was taken a stage further with the use of various metal stearates (e.g. magnesium stearate, calcium stearate, and zinc stearate) for modifying filler. The fillers examined were magnesium hydroxide and calcium carbonate. A filler loading of 40% w/w was used in all samples. Samples were moulded into a variety of shapes for mechanical testing. Such tests included, tensile, flexural, and impact testing. To obtain deeper understanding of the effect of the coating agents on the fillers, a variety of fundamental tests were carried out. These included Diffuse Reflectance FTIR (DRIFT), Thermal Analysis using a DSC cell, Xray Diffraction (XRD), contact angle measurement. Unfilled HDPE, uncoated filled-HDPE, and coated filled-HDPE were compared using uncoated filled-HDPE as a base line. Uncoated filled-HDPE is more brittle than unfilled HPDE. Surface modification of filler improves the toughness properties. Comparing coated filled-compounds, stearic acid and zinc stearate caused a small improvement, magnesium stearate improved the properties significantly with calcium carbonate while calcium stearate gave the best results for coating magnesium hydroxide. One monolayer coating gave the best compound properties compared to other degrees of coating. Although, tensile/flexural strength was not greatly affected elongation at yield, extension at maximum load, and impact properties increased significantly. DSC was used to observe the disappearance and conversion of coating agents as coating proceeded. X-ray diffraction showed the effect of injection moulding on the orientation of the filler and polymer. During coating of the filler particles, XRD and DSC were used to follow incorporation of stearate particles to produce the monolayer coverage. Surface free energy results showed that surface modification of filler resulted in the reduction of hydrophilicity of filler leading to tougher composites compared with uncoated filled-compounds.