Influence of migrating inhibitor concentration on corrosion resistance of steel reinforcement in concrete

To increase the service life and durability of reinforced concrete structures, new technologies have been developed, such as cathodic protection, re-alkalinization, chloride extraction, and the use of corrosion inhibitors. This study evaluated the influence of cement type, concrete cover thickness, and the addition of organic migrating corrosion inhibitor (MCI) on the corrosion resistance of the embedded steel in concrete against the induced action of chloride ions. To accomplish this, corrosion tests were carried out using electrode potential techniques simultaneously with acceleration cycles of chloride attack. Four mixtures with two levels of reinforcement cover (25 and 40 mm) were subjected to 30 weekly cycles of chemical attack: a reference mixture (without inhibitor) and three others adopting concentration levels of 0.30%, 0.45%, and 0.60% of MCI in the volume of concrete. The concrete properties (compressive strength, voids, specific gravity, and water absorption by immersion and capillarity) were verified. In the corrosion tests on reinforced concrete with lower cover thickness, the mixture with 0.60% MCI addition showed the best results: corrosion potential values less negative than -200 mV, with less than 10% probability of corrosion.Para aumentar a vida útil e durabilidade das estruturas de concreto armado foram desenvolvidas novas tecnologias como a proteção catódica, re-alcalinização, extração de cloreto, e o uso de inibidores de corrosão. Este estudo avaliou a influência do tipo de cimento, espessura do cobrimento de concreto e adição de inibidor de corrosão orgânico migratório (MCI) na resistência à corrosão do aço embutido no concreto contra a ação induzida de íons cloreto. Para isso, foram realizados ensaios de corrosão utilizando técnicas de potencial de eletrodo simultaneamente com ciclos de aceleração de ataque de cloretos. Quatro misturas com dois níveis de cobertura do aço (25 e 40 mm) foram submetidas a 30 ciclos semanais de ataque químico: uma mistura de referência (sem inibidor) e outras três adotando níveis de concentração de 0,30%, 0,45% e 0,60% de MCI em volume de concreto. As propriedades do concreto (resistência à compressão, índice de vazios, massa específica e absorção de água por imersão e capilaridade) foram verificadas. Nos ensaios de corrosão em concretos armados com menor espessura de cobrimento, a mistura com adição de 0,60% de MCI apresentou os melhores resultados: valores de potencial de corrosão inferiores a -200 mV, com probabilidade de corrosão inferior a 10%

EVALUATION OF THE THERMAL COMFORT IN CONTACT WITH CERAMIC TILES

In places where people are bare feet, the thermal sensation of cold or hot depends on the environmental conditions and material properties including its microstructure and crustiness surface. The uncomforting can be characterized by heated floor surfaces in external environments which are exposed to sun radiation (swimming polls areas) or by cold floor surfaces in internal environments (bed rooms, path rooms). The property named thermal effusivity which defines the interface temperature when two semiinfinite solids are putted in perfect contact. The introduction of the crustiness surface on the ceramic tiles interferes in the contact temperature and also it can be a strategy to obtain ceramic tiles more comfortable. Materials with low conductivities and densities can be obtained by porous inclusion are due particularly to the processing conditions usually employed. However, the presence of pores generally involves low mechanical strength. This work has the objective to evaluate the thermal comfort of ceramics floor obtained by incorporation of refractory raw materials (residue of the polishing of the porcelanato) in industrial atomized ceramic powder, through the thermal and mechanical properties. The theoretical and experimental results show that the porosity and crustiness surface increases; there is sensitive improvement in the comfort by contact

Propriedades de concreto auto-adensável contendo cinzas volantes

Self-compacting concrete is a high performance concrete with excellent rheological properties that can be spread in areas of difficult access. Selfcompacting concrete requires a high consumption of cement production, which has a negative effect on the environmental aspect, since the production of cement releases significant amounts of CO2. This study aims analysis the influence of the substitution (20 and 40% by weight) of Portland cement by fly ash on the selfcompacting concrete properties in the fresh state (spreading, workability, passing ability - J-ring test, viscosity - V-funnel test) and hardened (compressive strength).The passing ability was proved more effective to the mixture with 20% of replacement. To the viscosity, control concrete had lower flow time in V-funnel. The compressive strength results at 28 days showed a reduction of 9.5% for concrete with 20% fly ash and 77.0% for concrete with 40% fly ash compared to the control concrete.Self-compacting concrete is a high performance concrete with excellent rheological properties that can be spread in areas of difficult access. Selfcompacting concrete requires a high consumption of cement production, which has a negative effect on the environmental aspect, since the production of cement releases significant amounts of CO2. This study aims analysis the influence of the substitution (20 and 40% by weight) of Portland cement by fly ash on the selfcompacting concrete properties in the fresh state (spreading, workability, passing ability - J-ring test, viscosity - V-funnel test) and hardened (compressive strength).The passing ability was proved more effective to the mixture with 20% of replacement. To the viscosity, control concrete had lower flow time in V-funnel. The compressive strength results at 28 days showed a reduction of 9.5% for concrete with 20% fly ash and 77.0% for concrete with 40% fly ash compared to the control concrete

Preparation of molecularly imprinted poly(methacrylic acid) grafted on iniferter-modified multiwalled carbon nanotubes by living-radical polymerization for 17β-Estradiol Extraction

The synthesis of a nanocomposite based on molecularly imprinted poly(methacrylic acid) (MIP) grafted on an iniferter-modified carbon nanotube (MIP/MWCNT) by living-radical polymerization and its application for 17β-estradiol (E2) adsorption is described. The nonimprinted nanocomposite (NIP/MWCNT) and the polymers MIP and NIP synthesized in the absence of carbon nanotubes were also prepared and characterized by FT-IR, TGA, nitrogen adsorption–desorption measurements, and SEM and TEM techniques. From TEM images, a narrow layer of MIP at nanoscale onto MWCNT surface was formed, as expected by iniferter-controlled synthesis. The adsorption capacity of MIP/MWCNT toward E2 was higher than MIP. In addition, relative selectivity coefficients (k′) higher than one unit were obtained from competitive adsorption studies in the presence of estrone, 17α-ethynylestradiol, and bisphenol A, thereby demonstrating that MIP/MWCNT is more selective toward E2 when compared to NIP/MWCNT. Equilibrium adsorption of E2 was reached at 120 min and the maximum adsorption capacity of the nanocomposite was found to be 40.0 mg g–1, showing higher or similar performance when compared with others adsorbent materials described on the literature for E2. Thermodynamic parameters suggest that the adsorption process is spontaneous and of exothermic nature. The performance of MIP/MWCNT as a new packing adsorbent material was evaluated for E2 extraction in solid-phase extraction (SPE) procedure, which was performed by loading the sample at pH 7.0 through 50.0 mg of MIP/MWCNT packed into SPE cartridge. Taking into account the high elution value of 96 ± 3.6% obtained by using acetone:chloroform (1:1 v/v), as well as the selectivity of adsorbent, we can infer that MIP/MWCN/T nanocomposite shows interesting analytical potentiality for E2 preconcentration from natural water samples64519781990CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP481669/2013-2; 305552/2013-9; 472670/2012-3; 465389/2014-73353/2014; 23038.007082/2014-032014/50867-3The authors acknowledge the financial support and fellowships of Coordenação de Aperfeiçoamento de Nível Superior (CAPES) (Project Pró-Forenses 3353/2014 Grant 23038.007082/2014-03), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) (Grants 481669/2013-2, 305552/2013-9, 472670/2012-3), Fundação Araucária do Paraná (163/2014), SETI do Paraná, and Instituto Nacional de Ciência e Tecnologia de Bioanalítica (INCT) (FAPESP Grant 2014/50867-3 and CNPq Grant 465389/2014-7

Resistance Exercise Training Improves Metabolic and Inflammatory Control in Adipose and Muscle Tissues in Mice Fed a High-Fat Diet

This study investigates whether ladder climbing (LC), as a model of resistance exercise, can reverse whole-body and skeletal muscle deleterious metabolic and inflammatory effects of high-fat (HF) diet-induced obesity in mice. To accomplish this, Swiss mice were fed for 17 weeks either standard chow (SC) or an HF diet and then randomly assigned to remain sedentary or to undergo 8 weeks of LC training with progressive increases in resistance weight. Prior to beginning the exercise intervention, HF-fed animals displayed a 47% increase in body weight (BW) and impaired ability to clear blood glucose during an insulin tolerance test (ITT) when compared to SC animals. However, 8 weeks of LC significantly reduced BW, adipocyte size, as well as glycemia under fasting and during the ITT in HF-fed rats. LC also increased the phosphorylation of AktSer473 and AMPKThr172 and reduced tumor necrosis factor-alpha (TNF-α) and interleukin 1 beta (IL1-β) contents in the quadriceps muscles of HF-fed mice. Additionally, LC reduced the gene expression of inflammatory markers and attenuated HF-diet-induced NADPH oxidase subunit gp91phox in skeletal muscles. LC training was effective in reducing adiposity and the content of inflammatory mediators in skeletal muscle and improved whole-body glycemic control in mice fed an HF diet

SCLEM on FM and EM stained tissue sections.

<p>(a) FM image of human skin tissue stained with DiIC18 fluorescence and uranyl acetate and osmium tetroxide for EM contrast. Scalebar 5 µm (b) BSE image of a selected region from (a), showing a cell nucleus not discernible in (a) (marked with a red arrow), and bundles of longitudinally and transversally cut collagen fibers. Scalebar is 5 µm (c, d) High-magnification images of the areas marked with (c) a red star, scalebar 1 µm, and (d) a yellow star, scalebar 2 µm.</p

Simultaneous Correlative Light and Electron Microscopy.

<p>(a) schematic lay-out for SCLEM, BSE: backscattered electrons, SE: secondary electrons, ETD: Everhard-Thornley detector, LED: light emitting diode, CCD: charge coupled device camera. (b) inside view of the integrated microscope for SCLEM showing optical objective lens in epi-configuration underneath sample holder and electron lens.</p