Application of non-isothermal cure kinetics on the interaction of poly(ethylene terephthalate) - Alkyd resin paints

Samples of paint (P), reused PET (PET-R) and paint/PET-R mixtures (PPET-R) were evaluated using DSC to verify their physical-chemical properties and thermal behavior. Films from paints and PPET-R are visually similar. It was possible to establish that the maximum amount of PET-R that can be added to paint without significantly altering its filming properties is 2%. The cure process (80-203°C) was identified through DSC curves. The kinetic parameters, activation energy (E a) and Arrhenius parameters (A) for the samples containing 0.5 to 1% of PET-R, were calculated using the Flynn-Wall-Ozawa isoconversional method. It was observed that for greater amounts of PET-R added, there is a decrease in the E a values for the cure process. A Kinetic compensation effect (KCE), represented by the equation InA=-2.70+0.31E a was observed for all the samples. The most suitable kinetic model to describe this cure process is the autocatalytic Šesták-Berggreen, model applied to heterogeneous systems. © 2007 Springer Science+Business Media, LLC.

Dietary α-tocopheryl acetate on fillet quality of tilapia

This work compared the effects of dietary α-tocopheryl acetate on storage life of tilapia fillets. Three experimental diets containing increasing a-tocopherol levels (zero, 100, and 200 mg kg-1) were used. The fish, with a mean initial weight of 184.23 ± 1.68 g, were fed diets for 63 days. After that period, they were slaughtered, filleted, and the fillets were grounded to accelerate lipid oxidation. Fish growth, survival, fillet yield, chemical composition and lipid oxidation of tilapia ground fillets were evaluated 0, 30 and 60 days after frozen storage. The results demonstrated that there was no significant difference between treatments for performance, and also, tocopherol did not influence the chemical composition values of fillets. Increased tocopherol levels in the feeds promoted a reduction in ground fillets lipid oxidation values.

Clinical assessment of ethinylestradiol and cyproterone acetate in menstrual irregularities of hyper-androgenic origin

We report on the results of a double-blind, randomized, controlled clinical trial comparing two preparations of ethinylestradiol and cyproterone acetate in the treatment of women of reproductive age presenting menstrual irregularities of hyper-androgenic origin. After obtaining informed consent, subjects were randomized to a 4-month treatment period consisting of one daily dose of 0.035mg ethinylestradiol + 2mg cyproterone acetate. The treatment regimen cycle consisted of one pill, once daily for 21 days, followed by a 7-day pill-free period. We compared the efficacy of two presentations of the drug combination after each treatment cycle (Visits 2, 3, 4, and 5) in establishment and maintenance of menstrual regulation, intensity of menstrual flow, and dysmenorrhea, as well as a comparison of the two presentations in terms of Global Satisfaction and Drug Satisfaction assessments performed by the patients and the investigating physician. At each study visit, drug compliance and use of concomitant medications, as well as incidence, severity and duration of adverse events were recorded. A total of 86 subjects were randomized to treatment, with 43 subjects in each treatment group. At Visit 2 and each subsequent visit, all patients in both treatment groups reported an episode of withdrawal bleeding during the 7-day hormone-free period. We observed a statistically significant (p<0.0001) decrease in the incidence of dysmenorrhea at each study visit in relation to the pretreatment assessment. There was a significant reduction (p<0.0001) in the number of subjects reporting intermenstrual bleeding at each study visit in both treatment groups. Global Satisfaction scores by the patient and physician increased significantly at each successive study visit in both treatment groups. There were no clinically significant changes in vital signs, weight, and body mass index throughout the study period in either group. The number of subjects reporting adverse events at each visit did not vary between treatment groups. The combined oral contraceptive pill containing ethinylestradiol and cyproterone acetate was found to be both effective and safe in the menstrual irregularities of hyper-androgenic origin (amenorrhea, dysmenorrhea, and intermenstrual bleeding) assessed in this study. © Copyright Moreira Jr. Editora. Todos os direitos reservados.

Effects of the ethyl acetate fraction of Alchornea triplinervia on healing gastric ulcer in rats

Alchornea triplinervia (Spreng.) Muell. Arg (Euphorbiaceae) is a medicinal plant commonly used by people living in the Cerrado region of Brazil to treat gastrointestinal ulcers. We previously described the gastroprotective action of methanolic extract (ME) of Alchornea triplinervia and the ethyl acetate fraction (EAF) in increasing of prostaglandin E 2 (PGE 2) gastric levels in the mucosa. In this work we evaluated the effect of EAF in promoting the healing process in rats with acetic acid-induced gastric ulcers. In addition, toxicity was investigated during treatment with EAF. After 14 days of treatment with EAF, the potent stimulator of gastric cell proliferation contributed to the acceleration of gastric ulcer healing. Upon immunohistochemical analysis, we observed a pronounced expression of COX-2, mainly in the submucosal layer. The 14-day EAF treatment also significantly increased the number of neutrophils in the gastric mucosa regeneration area. The EAF induced angiogenesis on gastric mucosa, observed as an increase of the number of blood vessels supplying the stomach in rats treated with EAF. Oral administration for 14 days of the ethyl acetate fraction from Alchornea triplinervia accelerated the healing of gastric ulcers in rats by promoting epithelial cell proliferation, increasing the number of neutrophils and stimulation of mucus production. This fraction, which contained mainly phenolic compounds, contributed to gastric mucosa healing. © 2011 by the authors; licensee MDPI, Basel, Switzerland.

Antiulcer effects of Ethyl acetate fraction of Carpolobia lutea leaf

Carpolobia lutea leaves (CLL) (Polygalaceae) were earlier screened and the antiulcer ethnomedicinal claim established. This article seeks to quantitatively isolate, elucidate the active compounds from most active CLL fraction. Fractionation was by semi-preparative HPLC; the active fraction was subjected to radical scavenging assays (RSA) and quantification of the total phenolic content (TPC) were also executed. Results: Ethyl acetate fraction (EAF) was observed to be the most pharmacologically active antiulcer fraction when screened using acute ulcer models induced in rodents. The EAF demonstrated significant (p < 0.05-0.001) antiulcer activity in various in vivo induced ulceration models by reducing the ulcer index and increasing the preventive ratio. The EAF demonstrated > 70% in TPC and < 20 % in RSA. Cinnamic and coumaric acids derivatives were isolated from EAF. Cinnamic acids have been implicated and patented as antiulcer agent. Isolated compounds could in part mediate the observed pharmacological activities which lend credence to its ethnobotanical uses.

Thermo-gravimetric analysis (TGA) after different exposures of high density polyethylene (HDPE) and poly vinyl chloride (PVC) geomembranes

This paper presents the results of thermogravimetric analysis (TGA) tests in PVC (1.0; 2.0 mm) and HDPE (0.8; 2.5 mm) geomembranes exposed to weathering and leachate after 30 months. The aim of this paper is the comparison of fresh and exposed samples to assess the degradation process concerning the total loss of mass of geomembranes. The exposure was conducted in accordance with the recommendations of ASTM standards. The TGA tests were carried out according to ASTM D6370 and E2105. Results show, for instance, that for PVC geomembrane the largest reductions of plasticizers occurred for samples exposed to weathering. The loss of plasticizers after the exposure contributed to the decrease of deformation and consequent increase in stiffness. TGA tests shows to be a valuable tool to control the quality of the materials. © 2012 ejge.

Functional nanostructured catalysts based on the niobates to the dry methane reforming and ethylene homologation reactions

Catalytic activity and selectivity of niobate-based nanostructured materials were investigated. Dry methane reforming (DMR) and ethylene homologation reaction (EHR) were selected as test reactions. KSr 2Nb5O15, Sr2NaNb5O 15 and NaSr2(NiNb4)O15 δ niobate powders were prepared by the high energy ball milling method and calcined in a reductor atmosphere. N2 adsorption isotherms, X-ray diffraction and infrared spectroscopy characterization was performed. Hydrogen pretreated niobates showed from low to moderate catalytic initial activity in DMR's test, nevertheless the materials were deactivated rapidly and the kinetic parameters associated to deactivation were estimated. Otherwise, non-treated catalysts showed a high initial activity in EHR's test and KSr2Nb 5O15 catalyst requires 24 h to the total deactivation with a high selectivity to form propylene. A reaction mechanism to the propylene formation is discussed. © 2012 Elsevier Ltd. All rights reserved.

Voltammetric determination of ethyl acetate in ethanol fuel using a Fe 3+/Nafion®-coated glassy carbon electrode

A voltammetric method for the determination of ethyl acetate in ethanol fuel using a Fe3+/Nafion®-coated glassy carbon electrode (GCE) is proposed. The ethyl acetate present in the ethanol fuel was previously converted to acetohydroxamic acid via pretreatment with hydroxylamine chloride. The acetohydroxamic acid promptly reacted with the iron (III) present in the film, producing iron (III) acetohydroxamate, which presents a well-defined voltammetric peak current at -0.02 V. Optimization of the voltammetric parameters for the cyclic, linear sweep, square wave, and differential pulse modalities was carried out for this chemically-modified electrode. Square wave voltammetry afforded the best response for acetohydroxamic acid detection. The analytical curve for this species was linear from 9 to 100 μmol L 1 according to the following equation: ip (μA) = 0.27 + 2.55Cacetohydroxamic acid (μmol L 1), with linear correlation coefficient equal to 0.993. The technique presented limit of detection equal to 5.3 μmol L 1 and quantification limit of 17.6 μmol L 1. The proposed method was compared to the official method of ethyl acetate analysis (Gas Chromatography), and a satisfactory correlation was found between these techniques. © 2012 Elsevier Ltd. All rights reserved.

Altering the adsorptive and electronic properties of Pt through poly(vinyl alcohol) adsorption

In the present paper we investigated the effect of adsorbed PVA on Pt electrodes on classic electrochemical processes such as hydrogen UPD, oxygen reduction and CO electro-oxidation. Upon adsorption PVA blocks roughly 50% of the hydrogen sites and can not be removed from the Pt surface through cycling in the potential range of 0.05-1.0 V vs. RHE. Potentiodynamic experiments under controlled hydrodynamic conditions provided by rotating disk electrode experiments showed a negative impact of the adsorbed PVA on the oxygen reduction reaction (ORR). Cyclic-voltammetry results revealed that not even CO was able to remove PVA from the Pt surface. Regarding the oxidation of CO, the adsorbed polymer positively shifted the CO oxidation peak potential, therefore higher potentials are required to free the Pt surface from CO poisoning. In situ Fourier transform infrared spectroscopy evidenced that the presence of PVA shifted the linearly bound CO frequency toward higher wavenumbers, a process found to be independent of the Pt surface orientation. In situ electrochemical X-ray absorption spectroscopy results showed that PVA also impacted the electronic properties of platinum by decreasing the occupancy of the Pt conducting 5d band. Our findings clearly support the efforts toward understanding the nature of the interaction between polymers and metallic surfaces as well as the impact on technological applications (e.g. in PEMFCs). © 2013 Elsevier Ltd. All rights reserved.

Dielectric behavior of epoxy/BaTiO3 composites using nanostructured ceramic fibers obtained by electrospinning

Composite materials made of epoxy resin and barium titanate (BT) electrospun nanostructured fibers were prepared. BT fibers were synthesized from a sol based on barium acetate, titanium isopropoxide, and poly(vinyl pyrrolidone). The fibers were heat-treated at different temperatures and characterized by X-ray diffraction, scanning electron microscopy (SEM), and Raman spectroscopy. Mats of BT fibers heat-treated at 800 C were embedded in epoxy resin into suitable molds. The composites were characterized by SEM, and dielectric measurements were performed by means of dielectric spectroscopy. The dielectric permittivity and dielectric modulus of epoxy resin/BT-fiber composites were measured for two types of samples: with the electrodes parallel and perpendicular to the BT fiber layers. Interestingly, composite samples with electrodes perpendicular to the fiber layers and a BT content as low as 2 vol % led to dielectric permittivities three times higher than that of pure epoxy resin. © 2013 American Chemical Society.

The use of polylactic and polyglycolic copolymer biomaterial in a pre-clinical model of compromised primary stability

Aim Primary implant stability can be compromised by overdrilling of the implant bed. Filling the gap between the implant and the bone with a highly viscous copolymer of polylactic and polyglycolic acid (PLA/PGA) might stabilize the implant and thus supply osseointegration. The aim of this study was to evaluate implants installed in overdrilled beds associated with PLA/PGA in rats tibia model by means of removal torque test and fluorochrome analysis. Materials and methods For this experiment two groups were selected: in the test group 0.4 mm overdrilled defects (2.0 in diameter and 3 mm long ) were produced in the right tibia of seven rats and implants were placed covered with PLA/PGA biomaterial to fill the gap; the control group was not overdrilled and the implants were placed without the biomaterial. Implants of 1.6 mm in diameter and 3 mm long where placed into all defects. Calcein, alizarin and oxytetracyclin were injected at 7, 15 and 21 postoperative days, respectively, and the animals were sacrificed at 35 postoperative day. Results The results showed that all the implants achieved osseointegration. There were no statistical significance differences in torque-reverse and fluorocrome analysis (P>0.05). Conclusion We can conclude that overdrilled defects filled with PLA/PGA did not disturb osseointegration in this experimental model. © ARIESDUE.

Rheological behavior of binary aqueous solutions of poly(ethylene glycol) of 1500 g·mol-1 as affected by temperature and polymer concentration

The rheological behavior of poly(ethylene glycol) of 1500 g·mol -1(PEG1500) aqueous solutions with various polymer concentrations (w = 0.05, 0.10, 0.15, 0.20 and 0.25) was studied at different temperatures (T = 283.15, 288.15, 293.15, 298.15 and 303.15) K. The analyses were carried out considering shear rates ranging from (20 to 350) s-1, using a cone-and-plate rheometer under controlled stress and temperature. Classical rheological models (Newton, Bingham, Power Law, Casson, and Herschel-Bulkley) were tested. The Power Law model was shown suitable to mathematically represent the rheological behavior of these solutions. Well-adjusted empirical models were derived for consistency index variations in function of temperature (Arrhenius-type model; R2 > 0.96), polymer concentration (exponential model; R2 > 0.99) or the combination of both (R 2 > 0.99). Additionally, linear models were used to represent the variations of behavior index in the functions of temperature (R2 > 0.83) and concentration (R2 > 0.87). © 2013 American Chemical Society.

Gastroprotective mechanisms of the chloroform and ethyl acetate phases of Praxelis clematidea (Griseb.) R.M.King & H.Robinson (Asteraceae)

Flavonoid-rich Praxelis clematidea (Griseb.) R.M.King & H.Robinson (Asteraceae) is a native plant of South America. This study evaluates the gastroprotective activity and possible mechanisms for both the chloroform (CHCl3P) and ethyl acetate phases (AcOEtP) obtained from aerial parts of the plant. The activity was investigated using acute models of gastric ulcer. Gastric secretion biochemical parameters were determined after pylorus ligature. The participation of cytoprotective factors such as mucus, nitric oxide (NO), sulfhydryl (SH) groups, prostaglandin E2 (PGE 2), reduced glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), reduction of lipid peroxidation (malondialdehyde level), and polymorphonuclear infiltration (myeloperoxidase activity), was also investigated. CHCl3P (125, 250, and 500 mg/kg) and AcOEtP (62.5, 125, and 250 mg/kg) showed significant gastroprotective activity, reducing the ulcerative index by 75, 83, 88 % and 66, 66, 81 % for ethanol; 67, 67, 56 % and 56, 53, 58 % for a non-steroidal anti-inflammatory drug (NSAID); and 74, 58, 59 % and 64, 65, 61 % for stress-induced gastric ulcer, respectively. CHCl3P (125 mg/kg) and AcOEtP (62.5 mg/kg) significantly reduced the ulcerative area by 78 and 83 %, respectively, for the ischemia-reperfusion model. They also did not alter the biochemical parameters of gastric secretion, the GSH level or the activities of SOD, GPx or GR. They increased the quantity of gastric mucus, not dependent on NO, yet dependent on SH groups, and maintained PGE2 levels. The P. clematidea phases demonstrated gastroprotective activity related to cytoprotective factors. © 2012 The Japanese Society of Pharmacognosy and Springer.

Design of biogas pipeline - Energy and sanitation

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Preparação e caracterização de sílicas mesoporosas

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