EXPERIMENTAL MEASUREMENT OF INTERNAL TEMPERATURE OF A TUBE IN COOLING ON A BED OF PASSAGECONTINUOUS UNDER NATURAL CONVECTION

The process behind manufacturing bars and profiles in the steel industry utilizes heating and cooling at controlled rates in order to facilitate changes in their geometries, as well as to obtain desired changes in mechanical steel properties.This work develops an experimental procedure to reproduce the thermal behavior tubes over a cooling bed. In literature the experimental results obtained by Damasceno (2004) do not take into account the temperature measurements of the sidewalls and the floor below the bed and storage temperatures within and outside the shed. These failures compromise the claim to validate the mathematical model of Souza (2015) and therefore new measurements were obtained with room temperatures controlled, order to validate the mathematical model of a cooling bed heat treatment of steel mill Vallourec Tubes, located in Belo Horizonte, Brazil

Ageing effects on the wettability behavior of laser textured silicon

In the present work we investigate the ageing of acid cleaned femtosecond laser textured silicon surfaces. Changes in the surface structure and chemistry were analysed by Rutherford backscattering spectrometry (RBS) and X-ray photoelectron spectroscopy (XPS), in order to explain the variation with time of the water contact angles of the laser textured surfaces. It is shown that highly hydrophobic silicon surfaces are obtained immediately after laser texturing and cleaning with acid solutions (water contact angle >120 degrees). However these surfaces are not stable and ageing leads to a decrease of the water contact angle which reaches a value of 80 degrees. XPS analysis of the surfaces shows that the growth of the native oxide layer is most probably responsible for this behavior. (C) 2010 Elsevier B.V. All rights reserved

Influence of Activation Parameters on the Mechanical and Microstructure Properties of an Alkali-Activated BOF Steel Slag

ABSTRACT: Steel slag (SS) is a secondary material from steelmaking production with little commercial value. Its volumetric expansion and low reactivity limit the use of SS in Portland cement (PC)- based materials. This study investigated the potential use of basic oxygen furnace (BOF) slag as a single precursor in alkali-activated matrices (AAMs). Six AAM pastes were assessed by changing the silica modulus (0.75, 1.50 and 2.22) and the sodium concentration (4% or 6% Na2O?wt. SS). The early hydration was assessed using isothermal calorimetry (IC), followed by the assessment of the mechanical performance (compressive strength), apparent porosity, and structure and microstructure characterization (X-ray diffraction, thermogravimetric analysis and scanning electron microscopy). The results indicated that although the BOF slag may be considered a low-reactivity material, the alkaline environment effectively dissolved important crystalline phases to produce hydrates (reaction products). An optimized combination of activator sources was achieved with 4% Na2O and a silica modulus of 1.50?2.22, with a compressive strength up to 20 MPa, a significant amount of reaction products (C-S-H/C-A-S-H gels), and low initial and cumulative heat release. Those properties will help to promote SS recycling use in future engineering projects that do not require high-strength materials.This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES)—finance code 001, grant PPM-00709-18 (FAPEMIG) and grant 316882/2021-6 (CNPq

Effect of the carbon nanotube surface characteristics on the conductivity and dielectric constant of carbon nanotube/poly(vinylidene fluoride) composites

Commercial multi-walled carbon nanotubes (CNT) were functionalized by oxidation with HNO3, to introduce oxygen-containing surface groups, and by thermal treatments at different temperatures for their selective removal. The obtained samples were characterized by adsorption of N2 at -196°C, temperature-programmed desorption and determination of pH at the point of zero charge. CNT/poly(vinylidene fluoride) composites were prepared using the above CNT samples, with different filler fractions up to 1 wt%. It was found that oxidation reduced composite conductivity for a given concentration, shifted the percolation threshold to higher concentrations, and had no significant effect in the dielectric response

Microwave hydrodiffusion and gravity: an emergent technology for green extraction of non-volatile compounds

Microwave technologies are more and more present in food applications due to their performance in shortening the time of treatments such as drying, pasteurization, defrosting, or postharvesting. While solvent-free microwave extraction has been extensively used as a green procedure for essential oil and volatile compounds from aromatic herbs [1], its applications have been extended to enhance extraction of phytocompounds simultaneously with drying. In this work, microwave hydrodiffusion and gravity was performed in a laboratory microwave oven (NEOS-GR, Milestone, Italy), in order to evaluate its efficiency in the extraction of nonvolatile compounds such as: free sugars, f1bers, colour, and phenolic compounds. Five different matrices were tested: broccoli by-products (90% moisture), apple pomace (80% moisture), spent coffee grounds (65% moisture), Pterospartum tridentatum inflorescences, and brown algae, the latter two in dried state. The flow behaviour was very dependent on matrix (Figure 1): for broccoli, the time to obtain 50 ml aliquots increased along time while for apple pomace it was always the same after the initial and final heating periods, and for the spent coffee grounds it was always decreasing. Good recoveries were observed when using high water content matrices, such as apple pomace and broccoli. However, when using hydrated matrices, such as brown algae and Pterospartum tridentatum inflorescences, it was observed that the amount of material extracted is very low. In the case of spent coffee qrounds (a material where water is added to the ground coffee when preparing espresso coffee), the initial low recoveries can be overcome by the eo-addition of ethanol, allowing to obtain fractions rich in phenolic compounds, as well as brown compounds (with antioxidant activity) and caffeine. NEOS-GR, using microwave hydrodiffusion and gravity is a green extraction technology obtain hydrophilic compounds from wet matrices using its own water, allowing the extraction of valuable non-volatile compounds.info:eu-repo/semantics/publishedVersio

Microwave hydrodiffusion and gravity: an emergent technology for green extraction of non-volatile compounds

Microwave technologies are more and more present in food applications due to their performance in shortening the time of treatments such as drying, pasteurization, defrosting, or post-harvesting [1]. While solvent-free microwave extraction has been extensively used as a green procedure for essential oil and volatile compounds from aromatic herbs [2], its applications have been extended to enhance extraction of phytocompounds simultaneously with drying. In microwave drying, operational cost is lower because energy is not consumed in heating the walls of the apparatus or the environment [3].info:eu-repo/semantics/publishedVersio

The influence of rice husk ash addition on the properties of metakaolin-based geopolymers

This paper investigates the replacement of metakaolin (MK) with rice husk ash (RHA) in the production of alkali-activated binders or geopolymers. The influence of the RHA addition on compressive and flexural strength, as well as water absorption and apparent porosity were determined, in terms of the percentage of RHA in the mixture and molar ratios of the mixes. Fourier Transform Infrared (FTIR) spectroscopy and Energy Dispersive spectroscopy (EDS) were carried out to assess the changes in the microstructure of the geopolymer matrices with the RHA addition. Results have shown that RHA may be a supplementary precursor for geopolymers. The composition of the geopolymer matrices containing 0-40% RHA is very similar, which indicates that the additional Si provided by RHA is not incorporated to the geopolymer matrix. In addition, geopolymers with RHA content higher than 40% present a plastic behavior, characterized by extremely low strength and high deformation, which can be attributed to the formation of silica gel in formulations containing variable Si/Al ratio

The Cystic Mesothelioma: case report

Introduction: the cystic mesothelioma of the peritoneum (MCP) is a rare disease, with few reported cases. The first description was made by Smith and Mennemeyer in 1979. It is an intra-abdominal tumor that occurs most frequently in women of reproductive age. Objective: To describe the case of Mesothelioma Cystic the peritoneum due to rarity of this tumor, the similarity of their symptomatic presentation with other diseases, the lack of specific symptoms and characteristics of imaging and its diagnosis difficult, based on postoperative histological findings. Case report: A 45 years old and female, presented abdominal pain in the right upper quadrant lasting 6 months. During investigation was evidenced in computerized tomography a massive hypodense formation, net multiseptada. Its surgical hysterectomy for uterine perforation history. Forwards for surgery with macroscopic findings of retroperitoneal cystic lesion, complex and voluminous suggestive of Mesothelioma Cystic peritoneal. Conclusion: This tumor is known for its local recurrence, and surgery was the only effective treatment