Fatigue and quasi-static analysis of a new type of surface preparation used for the CFRP repair of steel offshore structures

ABSTRACT

In recent years, there has been an increasing interest in repairing offshore steel structures by using adhesively joined carbon fiber reinforced polymers (CFRP). For such procedure, surface preparation plays a vital role to maintain the integrity of the joint and to ensure proper load transfer. The primary surface preparation used by the oil and gas industry is the grit blasting due to its known quality. However, the logistic required is a major drawback limiting the use of adhesively joined repairs. Other surface preparation procedures available are unable to promote proper treatment. In this paper, an alternative surface preparation methodology employing a portable machine that uses rotation and impact to treat the steel surface was evaluated by quasi-static and fatigue tests of CFRP/steel adhesively bonded using the double-lap joints. The joints were prepared using non-corroded and severely corroded steel surfaces treated by grit blasting or rotating impact machine. The corroded plate was used to evaluate the efficiency of the rotating impact machine in removing deeply penetrating oxides. Test results showed that the performance of the machine was comparable to grit blasting even for the severely corroded surface with deep pitting. Corrosion in the metallic substrate impaired the quasi-static and fatigue properties.     

Green supply chain management in local and multinational high-tech companies located in Brazil

The objective of this article is to analyse how green supply chain management (GSCM) practices are being adopted by some high-tech companies located in Brazil. The research was conducted using the case study approach, focusing on eight companies that are representative of this sector. The main results are: (a) the most adopted GSCM practices in the studied high-tech companies located in Brazil are internal environmental management, investment recovery and reverse logistics and (b) Brazilian environmental legislation and international policies are very important in driving the adoption of GSCM practices. The internationalisation of companies was also found to be a variable that interferes with the adoption of GSCM practices. This is one of the first studies that examine the relationship between GSCM and the internationalisation of companies located in Brazil.     

Synthesis and Characterization of Aluminum–Zirconium Intermetallic Composites

The search for composite materials comes from a necessity of improving properties of conventional materials. The reaction synthesis process frequently gives products with some level of porosity that may be improved through the use of hot pressing routes. The combination of aluminum and zirconia in controlled conditions has led to a metal matrix composite with a dispersion of intermetallics, especially Al₃Zr. Temperature, pressure, and chemical composition were the main parameters varied during the production of the samples. The experimental procedures consisted initially of the mixing and homogenization of the powders in three proportions (5, 10, and 20 in zirconia wt. %). The powders were pressed for the production of green bodies, cylinders of 9 × 9 mm, with the application of three pressures (150, 250, and 300 MPa). Synthesis was carried out in a tubular furnace (1073, 1173, and 1273 K) using a helium atmosphere. Reactive hot pressing was carried out in a MTS machine. The densification process in the simultaneous hot pressing was observed with the use of mercury picnometry to measure the densities and confirmed with the help of an image analyzer. The temperatures were monitored by a thermocouple connected to an A/D interface. Determination of Vickers microhardness was carried out in the aluminum matrix and in the intermetallic particles; hardness was determined in all samples. The identification of the phases was obtained utilizing XRD, optical, and SEM microscopy.     

Mercury methylation and bacterial activity associated to tropical phytoplankton

The methylated form of mercury (Hg), methylmercury (MeHg), is one of the most toxic pollutants. Biotic and/or abiotic methylation, often associated to sulfate-reducing bacteria metabolism, occurs in aquatic environments and in many tropical areas, mostly in the periphyton associated to floating macrophyte roots. Data about mercury methylation by phytoplankton are scarce and the aim of this study was to verify the biotic influence in the methylation process in Microcystis aeruginosa and Sineccocystis sp. laboratory strains and in natural populations of phytoplankton from two different aquatic systems, the mesotrophic Ribeir?o das Lajes reservoir and hypereutrophic oligohaline Jacarepaguá lagoon, Rio de Janeiro state, Brazil. Adapted radiochemical techniques were used to measure sulfate-reduction, mercury methylation and bacterial activity in phytoplankton samples. Methyl-(203)Hg formation from added inorganic (203)Hg and (3)H-Leucine uptake were measured by liquid scintillation as well as sulfate-reduction, estimated as H(2)(35)S produced from added Na(2)(35)SO(4). There was no significant difference in low methylation potentials (0.37%) among the two cyanobacterium species studied in laboratory conditions. At Ribeir?o das Lajes reservoir, there was no significant difference in methylation, bacterial activity and sulfate-reduction of surface sediment between the sampling points. Methylation in sediments (3-4%) was higher than in phytoplankton (1.5%), the opposite being true for bacterial activity (sediment mean 6.6 against 150.3 nmol gdw(-1) h(-1) for phytoplankton samples). At Jacarepaguá lagoon, an expressive bacterial activity (477.1 x 10(3) nmol gdw(-1) h(-1) at a concentration of 1000 nM leucine) and sulfate-reduction ( approximately 21% H(2)(35)S trapped) associated to phytoplankton (mostly cyanobacteria M. aeruginosa) was observed, but mercury methylation was not detected.     

Supplemental protein plus ruminally protected methionine and lysine for primiparous beef cattle consuming annual rye hay

Primiparous beef cows (n = 35 Bos taurus, average initial BW of 498 kg) were allotted to treatments in a split-plot designed experiment to determine the effects of supplemental ruminally protected amino acids on cow and calf productivity and metabolic changes in the cows. Cows were fed chopped annual rye hay at 1.5% of BW. The following treatments were used: 1) .8 kg soybean hulls, 1.4 kg ground corn, .6 kg soybean meal (CON); 2) 1.4 kg ground corn, 1.4 kg soybean meal (PRO); 3) PRO plus ruminally protected methionine and lysine (supplied 5 and 10 g, respectively; PRO1); and 4) PRO with twice the level of ruminally protected amino acids in PRO1 (PRO2). Cow weight gain was not different (P > .26) among treatments and averaged 1.2 kg/d for the 45 + 6 d before parturition. After parturition, cow weight gain did not differ (P > .47) between CON and PRO treatments, but it decreased quadratically (P < .01) with increasing level of ruminally protected amino acids. Total milk yield, protein, and fat (4 h) were greater (P < .05) for cows consuming PRO supplements than for CON, whereas CON cattle tended (P = .11) to lose less body condition. Total milk protein showed a quadratic increase (P < .05) in response to level of ruminally protected amino acids that was the inverse of the quadratic response noted for cow weight gain. Serum urea N concentration was greater (P = .07) for cattle consuming additional protein. Metabolic hormones were not affected (P > .18) by dietary treatment, but they responded (P < .05) to changes in physiological state. Supplements with additional protein supported greater (P = .0001) milk urea N concentration and output. Milk urea N concentration increased (P < .05) and milk IGF-I decreased (P < .05) as the lactation period progressed. The measurement of CON and PRO diets revealed that supplements with additional soybean meal had greater (P < .05) DM and N degradation; the extent of forage DM and NDF degradation was similar (P > .05) among treatments. Production shifted away from body weight gain to increased milk protein production when daily supplementation of ruminally protected methionine and lysine increased from 5 and 10 to 10 and 20 g, respectively. This shift in production was not reflective of changes in the metabolic regulators measured.     

Outcome measures of a chronic pain program: a prospective statistical study

Ion beam enhanced deposition (IBED) was adopted to synthesize biocompatible titanium oxide film. Structure characteristics of titanium oxide film were investigated by RBS, AES, and XRD. The blood compatibility of the titanium oxide film was studied by measurements of blood clotting time and platelet adhesion. The results show that the anticoagulation property of titanium oxide film is improved significantly. The mechanism of anticoagulation of the titanium oxide film was discussed.     

Molecular cloning, expression, and characterization of a functional single-chain Fv antibody to the mycotoxin zearalenone

The heavy-chain and kappa light-chain variable region genes of an antizearalenone hybridoma cell line (2G3-6E3-2E2) were isolated by PCR and joined by a DNA linker encoding peptide (Gly4Ser)3 as a single-chain Fv (scFv) DNA fragment. The scFv DNA fragment was cloned into a phagemid (pCANTAB5E) and expressed as a fusion protein with E tag and phage M13 p3 in Escherichia coli TG1. In the presence of helper phage M13K07, the scFv fusion protein was displayed on the surfaces of recombinant phages. High-affinity scFv phages were enriched through affinity selection in microtiter wells coated with zearalenone-ovalbumin conjugate. The selected recombinant phages were used to infect E. coli HB2151 for the production of soluble scFv antibodies. One selected clone (pQY1.5) in HB2151 secreted a soluble scFv antibody (QY1.5) with a high zearalenone-binding affinity (concentration required for 50% inhibition of binding, 14 ng/ml), similar to that of parent monoclonal antibody in a competitive indirect enzyme-linked immunosorbent assay. However, scFv QY1.5 exhibited higher cross-reactivity with zearalenone analogs and had greater sensitivity to methanol destabilization than the parent monoclonal antibody did. Nucleotide sequence analyses revealed that the light-chain portion of scFv QY1.5 had a nucleotide sequence identity of 97% to a mouse germ line gene VK23.32 in mouse kappa light-chain variable region subgroup V, whereas the heavy-chain nucleotide sequence was classified as mouse heavy-chain subgroup III (D) but without any closely related members having highly homologous complementarity-determining region sequences. The potential of soluble scFv QY1.5 for routine screening of zearalenone and its analogs was demonstrated with zearalenone-spiked corn extracts.     

Alkaline hydrolysis of P(VAc-co-MMA) particles for vascular embolization procedures

Poly(vinyl acetate) (PVAc)-based particles are used in medical and biomedical applications, including vascular embolization (VE) procedures. However, to render the technique safer and reproducible, the hydrolysis of the microbeads must be performed in some applications in order to control the hydrophilicity of the material. For this reason, in the present work the alkaline hydrolysis of poly(vinyl acetate-co-methyl methacrylate)—P(VAc-co-MMA)—microbeads is investigated. The hydrolytic conversions of PVAc and poly(methacrylic acid) (PMMA) chains were evaluated in terms of the concentrations of methanol and acetate ions present in the reaction media, since these chemicals are by-products of alkaline hydrolyses of the ester groups of the polymers. It was observed that all investigated variables (temperature, time, and alkaline concentration) exert important effects on the final extents of hydrolysis, although the occurrence of nonlinear synergetic effects imposes the use of multivariable statistical analyses for proper characterization of variable effects. Besides, given the heterogeneous nature of the reaction system and the higher resistance to hydrolysis offered by PMMA segments, the overall hydrolytic conversions of the microbeads were low, as required in VE procedures. Finally, hydrolyses of P(VAc-co-MMA) chains can also lead to cleavage of polymer chains, as confirmed by reduction of average molar masses of the analyzed materials.