Fernando García‐Hernandez, Luis Hernández‐Sandoval, Carlos Regalado‐González, José Mojica‐Gómez, Yunny Meas‐Vong, Guillermo Espinosa‐Acosta, Miriam Estévez and Victor Castaño
The purpose of this paper is to study the corrosion of carbon steel without coating and when protected using three different hybrid coatings, i.e. a bi‐component polyurethane with…
Abstract
Purpose
The purpose of this paper is to study the corrosion of carbon steel without coating and when protected using three different hybrid coatings, i.e. a bi‐component polyurethane with nano‐particles of SiO2 with and without sacrificial anode particles, and a mono‐component polyurethane with SiO2 particles.
Design/methodology/approach
In this investigation three different nano‐structured coatings are developed and applied to steel substrates and then tested for their corrosion resistance (defined as “Rn”), under a very aggressive medium (pH=1.5) in a dynamic system (loop reactor). Their performance is evaluated using an electrochemical noise (EN) resistance technique. The electrodes are connected to a potentiostat and measurements are recorded as per the EN technique over a 2,048 s duration at 0, 24, and 48 h intervals. Scanning electron microscopy (SEM) are obtained before and after the corrosion trials to characterize the control and the different coating systems.
Findings
The results show that a bicomponent coating, made up of alkyd resin and silica nanoparticles demonstrated the best performance, whereas the coating formed by SiO2 nanoparticles and polyurethane resin showed relatively low corrosion resistance. The inclusion of zinc nanoparticles in a third coating as sacrificial nano‐anodes led to segregation and resulted in moderate corrosion resistance. These results are confirmed by SEM observations.
Originality/value
The results obtained in this paper provide an insight to the understanding of the anticorrosion properties of three different hybrid coatings in a dynamic system (loop reactor).
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Sergio M. Alcocer and Víctor M. Castaño
The purpose of this paper is to provide an overview of structural design code development in Mexico, as an example of how code evolution has taken place in many countries, and to…
Abstract
Purpose
The purpose of this paper is to provide an overview of structural design code development in Mexico, as an example of how code evolution has taken place in many countries, and to discuss the challenges faced in improving code compliance and reducing vulnerability.
Design/methodology/approach
All building codes for Mexico City (1920‐2004) and current codes in Mexico were analyzed and compared in terms of their scope and contents. Emphasis is placed on understanding how design requirements, professional liabilities and overall performance requirements have evolved.
Findings
Structural codes have become more refined and complex, including at each revision the current state‐of‐the‐art knowledge. However, code compliance and code misinterpretation are prevalent, mainly because users are not familiar with the concepts and technologies involved. Also, it is stated that government authorities lack the technical capacity to identify code misinterpretations. Finally, it is stated that, for non‐engineered construction guidelines, other educational sources are needed in lieu of merely enforcing codes.
Research limitations/implications
Systematic research aimed at assessing the level of code compliance is needed.
Practical implications
A valuable source of changes and challenges in code implementation and compliance for students and practitioners is provided.
Originality/value
This paper summarizes information on the evolution of Mexican structural codes and offers a critique of the challenges and need for improving code implementation and reducing building vulnerability.
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Jaime Horta‐Rangel, Socorro Carmona and Victor M. Castaño
Earthquakes can produce important damage in civil infrastructure, including buildings and bridges, representing an important impact on the economy of many countries. The damage is…
Abstract
Purpose
Earthquakes can produce important damage in civil infrastructure, including buildings and bridges, representing an important impact on the economy of many countries. The damage is particularly severe when the dominant frequency of the quake approaches one of the resonant frequencies of the structure. One typical failure occurs through the weakening of some beam‐column joints, generally along with the presence of cracking. The standard procedure for repairing this is by reinforcing the damaged zone with steel plates, sleeves or by means of a new section of reinforced concrete covering the old one. These arrangements change the mechanical stiffness and the mass of the structure itself. Accordingly, this work aims to study these mass and stiffness changes of structures through a non‐linear optimization of the modal analysis of the structure.
Design/methodology/approach
The paper analyzes the potential shifts in natural frequencies of the structure and thus proposes the best conditions under which a damaged bridge could be repaired efficiently.
Findings
In the cases analyzed a similar tendency was observed, namely, that the natural frequencies increase (i.e. diminish their period) with the increase of mass of the bottom columns and with the reduction of the uppers ones. The increase of frequencies by increasing the bottom sections seems to be a viable solution. It is observed that by carrying out the presented procedure it is possible to include more variables, in particular to consider not only the first frequency, but also higher orders.
Research limitations/implications
A purely theoretical approach has been taken in this study.
Originality/value
If confirmed by experimentation this study would have considerable interest to engineers undertaking repair works on earthquake damaged structures.
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Fernando Garcia, Ana Leonor Rivera Lopez, Juan Campos Guillén, Luis Hernández Sandoval, Carlos Regalado González and Victor Castaño
The purpose of this paper is to report a study of microbiological influenced corrosion (MIC) of copper due to bacteria strains isolated from potable water pipes and oxidation…
Abstract
Purpose
The purpose of this paper is to report a study of microbiological influenced corrosion (MIC) of copper due to bacteria strains isolated from potable water pipes and oxidation lagoons using electrochemical noise (EN) analysis and scanning electron microscopy (SEM).
Design/methodology/approach
Bacteria strains isolated from copper surfaces of potable water pipes and from oxidation lagoons were identified, based on the 16S rDNA gene sequence analysis. Corrosion studies were undertaken over a period of six weeks, placing copper electrodes inside an LB culture media with and without bacteria. The corrosion resistance was obtained using EN analysis. In all the cases, the corrosion type was identified. SEM images of the copper electrodes were taken to evaluate the surface condition.
Findings
The bacteria strains identified were: Pantoea agglomerans, Alcaligenes faecalis, Bacillus cereus, Brucellaceae bacterium, Enterobacter cloacae, Delftia tsuruhatensis, and Pseudochrobactrum asaccharolyticum. EN analysis gave noise resistance values in the range 1,036‐5,040 Ωcm2 for the control samples and in the range of 2,336‐22,573 Ωcm2 for samples that had been inoculated with bacteria. It was found that a decrease in the rate of corrosion took place due to the development of a biofilm by the microorganisms on the copper surface. SEM images corroborated the presence of the biofilm on the copper electrodes.
Practical implications
The isolated bacteria strain reduced the rate of corrosion on the copper electrodes, as shown by the SEM images and EN analysis results, due to the formation of a biofilm that can act as an anticorrosive coating.
Originality/value
Even though MIC is a known phenomenon, it has not been reported that isolated bacteria strains can reduce corrosion on the surface of copper potable water pipes and in oxidation lagoons.
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Victor Pozzobon and Clément Pozzobon
Cottage is a protein-rich food which is commonly consumed by people targeting weight reduction and athletes willing to eat whole-food instead of protein supplements. Yet out of…
Abstract
Purpose
Cottage is a protein-rich food which is commonly consumed by people targeting weight reduction and athletes willing to eat whole-food instead of protein supplements. Yet out of common knowledge, the scientific community lacks solid evidences of the effect of the inclusion of cottage cheese in a diet. The purpose of this paper is to assess the evidences from scientific literature of the impact of inclusion of cottage cheese in a diet.
Design/methodology/approach
PubMed and Web of Science were searched for scientific literature dealing with “cottage cheese” and “diet.” There was no restriction regarding the type article type, date nor journal it is published in. References found to during the analysis of the articles extracted from database were also included. Studies search, screening and eligibility analysis were led in parallel by two independent reviewers.
Findings
This survey shows that cottage cheese is a good source of calcium (with 83 mg/100 g) – but not low fat cottage cheese because of its low vitamin S content (p < 0.001) –, a source of probiotic (1 serving providing the recommended dietary intake), a source of high quality proteins, reduces postprandial blood glucose level – healthy and type II diabetes subjects – (p < 0.05), is not linked to increased cardiovascular diseases nor cancer risks (p < 0.05).
Originality/value
Based on the findings reported in this review, the inclusion of cottage cheese in a diet can be advised for: women to build up calcium storage to fight osteoporosis; more generally calcium/vitamin D deficient subjects; athletes willing to increase their high-quality proteins intake through whole food consumption; dieters looking for low energy, high protein, high satiety food; untreated type II diabetes patients by reducing postprandial glucose level.
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Gabriel Gomes da Cunha and Paulo Arvate
The purpose of this paper is to investigate the effect of government-led programs on the engagement of individuals in entrepreneurship.
Abstract
Purpose
The purpose of this paper is to investigate the effect of government-led programs on the engagement of individuals in entrepreneurship.
Design/methodology/approach
The authors worked with government-led programs of 16 European countries between 2003 and 2014 and were able to benefit from the 2008 natural experiment (i.e. the global financial crisis) to produce a robust investigation using a regression kink design (RKD).
Findings
The work shows that government-led programs that are designed to include monitoring schemes can significantly increase individuals' engagement in opportunity-driven entrepreneurship. The authors found that monitoring schemes do not have the same relevance for necessity-driven entrepreneurship. Therefore, the authors believe the difference occurs because monitoring design avoids problems related to moral hazard and adverse selection when it comes to individuals choosing whether to participate (or not) in government-led programs.
Originality/value
While it is important for governments to provide an enabling environment for entrepreneurship, this study showed that not all types of public program have positive results. In fact, it has been demonstrated that poorly-designed programs can actually decrease the likelihood of individuals engaging in entrepreneurial activities. The efficiency of programs is substantially improved, however, when they are designed to include monitoring schemes.