A. Pereira; Akasaki, JL.; J.L.P.Melges; Mitsuuchi Tashima, M.; Soriano Martinez, L.; Borrachero Rosado, MV.; Monzó Balbuena, JM.... (2015). Effect of sugarcane bagasse ash (SBA) added to alkali-activated blast furnace salg (BFS) AbstractSugarcane bagasse is an agricultural waste which can be transformed, for cementing purposes, into an interesting material by combustion. Specifically, the ash (SBA) obtained by autocombustion was used for preparing alkali-activated cements by blending blast furnace slag (BFS). SBA had a large amount of quartz; however, it reacted in high alkaline medium. Mixtures of BFS/SBA have been used for preparing alkali-activated mortars, by using NaOH (8M solution), sodium silicate (8M solution in Na + and SiO 2 /Na 2 O molar ratio of 0.5) and KOH (8M solution) as activating reagents. Replacements of 25, 33 and 50% of BFS by SBA were carried out and compressive strengths in the range 16-51 MPa were obtained after 90 curing days. Microstructural studies demonstrated that the hydration products formed in the activation of BFS are not significantly affected by the presence of SBA in the mixture. The durability of alkaliactivated mortars was compared to ordinary Portland cement (OPC) mortar in the following media: hydrochloric acid, acetic acid, ammonium chloride, sodium sulphate and magnesium sulphate. The behaviour of alkali-activated mortars with BFS and BFS/SBA was better than that found for plain OPC mortars, especially in ammonium chloride, acetic acid and sodium sulphate media. After 200 days of testing in ammonium chloride solution, the compressive strength loss for Portland cement mortar was about 83.3%. For the same test conditions, alkali-activated mortars presented a maximum reduction of 48.4%. The presence of SBA in alkali-activated BFS mortars did not produce any serious problems in durability. As a general conclusion, sugarcane bagasse ash (SBA) obtained by autocombustion showed good cementing properties as a mineral precursor blended with blast furnace slag (BFS) in alkali-activated systems.

This study has evaluated how the vascular endothelium of hypertensive rats chronically treated with apocynin affects acetylcholine (ACh), sodium nitroprusside (SNP), and phenylephrine (PE) action on the nitric oxide (NO) signal transduction pathway in endothelial (EC) and vascular smooth muscle cells. Treatment with apocynin significantly reduced the mean arterial pressure in spontaneously hypertensive rats (SHR). In addition, apocynin improved the impaired ACh hypotensive effect on SHR. Although systemic oxidative stress was high in SHR, SHR treated with apocynin and normotensive rats presented similar systemic oxidative stress levels. Endothelium significantly blunted PE contractions in intact aortas of treated SHR. The ACh effect was impaired in resistance arteries and aortas of SHR, but this same effect was improved in treated SHR. The SNP potency was higher in intact resistance arteries of treated SHR than in intact resistance arteries of untreated SHR. NO and calcium concentrations increased, whereas reactive oxygen species levels decreased in EC of treated SHR. Aortas of untreated and treated SHR did not differ in terms of sGC alpha or beta units expression. Aorta of treated SHR expressed higher eNOS levels as compared to aorta of untreated SHR. The study groups did not differ with respect to NOX1, NOXO1, or NOX4 expression. However, treatment with apocynin normalized overexpression of NOX2 and its subunit p47phox in aortas of SHR. Based on all the results presented in this study, we suggest apocynin increases NO biovailability by different mechanisms, restoring the proper function of vascular endothelium in SHR.

Perimenopause is a period in a woman's life that precedes menopause and is characterized by hormonal changes that result in increased oxidative stress. Since oxidative stress is associated with age-related diseases and perimenopausal symptoms including somato-vegetative manifestations, nutritional antioxidant supplementation may be an effective approach to minimizing this stress. Mate tea (MT) (Ilex paraguariensis), a typical and inexpensive beverage consumed in the Brazilian south-east, Argentina and Uruguay, increases antioxidant defense. We hypothesized that MT could minimize oxidative stress during perimenopause by modulating enzymatic antioxidant defense. To test this, we analyzed the lipid oxidative damage and antioxidant defense in erythrocytes and liver of rats, after MT treatment. Female Wistar rats (aged 16months) in proven perimenopause period received 20mg/kgBW/day of mate tea, by gavage (PM+MT group) or water (PM group). Female rats aged 4months (AD group) received water. Erythrocytes and liver were used to determine lipid oxidative damage, determined by malondialdehyde (MDA); superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) activities. Total plasma antioxidant capacity was examined by ferric reducing antioxidant power assay (FRAP) and estrogen by radioimmunoassay. MT increased FRAP and did not change estrogen levels. Increased SOD and GPx, and reduced MDA were observed in both tissues studied. Increased CAT activity was observed only in the liver. We confirmed the hypothesis that MT was capable of minimizing oxidative stress in this period of life by modulating antioxidant defense.

Aluminum alloys are extensively used in space programs for both structural and nonstructural applications. As is well known, the corrosion resistance of these alloys is quite limited and anticorrosion treatment is needed. Currently, the treatment most often used for improving the corrosion resistance of aluminum alloys is chromate (CrVI-based) conversion coatings (CCC). Due to the high environmental impact of these compounds, the REACH Regulation of the European Union decided to limit/restrict the use of hexavalent chromium. A sunset date of mid-2017 has been already set. For the time being, many chromatefree alternative products are available, but they have been found to be significantly inferior in terms of corrosion protection performances with respect to the chromate options. In this regard, there is a great need to develop high-performance hexavalent chromiumfree anticorrosion coatings with low environmental impact and conformity with the EU regulations. The European Space Agency (ESA) is currently involved in a frame contract with Instituto de Soldadura e Qualidade (ISQ) that is currently ongoing. The objective of this study is to evaluate the anticorrosion behavior of the different alternative pretreatments applied to the most used aluminum alloys. The outcome of this activity will be the identification and the optimization of the most promising anticorrosion pretreatment. Several commercial Cr(VI)-free processes were applied onto aluminum alloys (2024-T3 and 2024-T81) used in the construction of ESA spacecraft in order to investigate their anticorrosive properties compared with Alodine 1200, a widely used conventional CCC. One of these commercial processes presented good anticorrosion performance, even better than Alodine 1200, and these results are presented in this paper. Salt spray resistance is included in the testing program as well as metallurgical coating evaluations that include microscopy observations before and after testing and electrochemical impedance spectroscopy in order to evaluate surface and microstructural modifications due to degradation mechanisms. Further studies must be performed with this promising alternative, modifying application parameters in order to achieve improved corrosion protection efficiency.

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