The seas play an essential role for the peoples living on their coastal regions, since the marine infrastructure is located in the coasts. Seawater is a corrosive environment that affects infrastructure particularly in polluted seawater. Corrosion and pollution are pernicious chemical, physical processes that impair the quality of the environment and the durability of the marine structures and materials. They are aggravated by the discharge into the sea coast of municipal, industrial and agricultural effluents, which contain and produce toxic and highly corrosive components by biological and chemical degradation. Reinforced concrete and carbon steel are the main engineering materials used for the construction of marine installations and equipment but other metals and alloys: aluminium; copper, stainless steels are applied, too. Laboratory and field corrosion tests in seawater were carried out applying gravimetric, electrochemical and surface examination methods, based on American Society of Testing and Materials (ASTM) and National Association of Corrosion Engineers (NACE) standards. This work is the result of a cooperation between academic institutions in Mexico and Israel. The data generated advance the management of sea corrosion prevention and mitigation, and provide a guide for marine infrastructure maintenance and corrosion control. Several cases of corrosion in the sea coasts based on the authors experience and knowledge are presented.

The present work discusses the problem of induced external electrical noise as well as its removal from the electrical potential obtained from Scanning Vibrating Electrode Technique (SVET) in the pitting corrosion process of aluminum alloy A96061 in 3.5% NaCl. An accessible and efficient solution of this problem is presented with the use of virtual instrumentation (VI), embedded systems, and the discrete wavelet transform (DWT). The DWT is a computational algorithm for digital processing that allows obtaining electrical noise with Signal to Noise Ratio (SNR) superior to those obtained with Lock-In Amplifier equipment. The results show that DWT and the threshold method are efficient and powerful alternatives to carry out electrical measurements of potential signals from localized corrosion processes measured by SVET.

Hydrogen sulphide (H₂S) is considered one of the most corrosive atmospheric pollutants. It is a weak, diprotic, reducing acid, readily soluble in water and dispersed into the air by winds when emitted from natural, industrial, and anthropogenic sources. It is a pollutant with a high level of toxicity impairing human health and the environment quality. It attacks copper forming thin films of metallic sulphides or dendrite whiskers, which are cathodic to the metal substrate, enhancing corrosion. H₂S is actively involved in microbially influenced corrosion (MIC) which develops in water, involving sulphur based bacteria, in oxidizing and reducing chemical reactions. H₂S is found in concentrated geothermal brines, in the atmosphere of geothermal fields, and in municipal sewage systems. Other active atmospheric pollutants include SO_X, NO_X, and CO. This investigation reports on the effects of H₂S on copper in microelectronic components of equipment and devices, with the formation of nonconductive films that lead to electrical failures.

Biological extracts have recently shown a great potential for rapid biosynthesis of silver nanoparticles (AgNPs) with antibacterial activity. AgNPs were synthetized by reduction effect of secondary metabolites produced by the Nigrospora sp. fungus, from Moringa oleifera stem as a reducing agent and silver nitrate (AgNO3) (1 mM) as salt precursor. The synthesis of nanoparticles (NPs) was monitored through analysis of the UV-Vis spectroscopy absorption in the 436 to 440 nm range indicating the presence of AgNPs in the colloidal aqueous solutions. Fourier transform infrared spectroscopy (FTIR) spectra were performed to identify the compounds responsible for the bio reduction of the Ag+. The morphology and sizes of AgNPs were characterized by scanning electron microscopy (SEM), energy dispersive of X-ray spectroscopy (EDS), dynamic light scattering (DLS), and colloid stability by zeta potential measurements. The NPs obtained were spherical in shape with size in the 3 to 70 nm range. Antibacterial activity was confirmed by evaluation of their effect against Escherichia coli, Klebsiella cloacae and Staphylococcus epidermidis. The proposed green synthesis of AgNPs from secondary metabolites produced by the Nigrospora sp. fungus from M. oleifera stem can be strongly recommended as a potential method for biomedical application. Key words: Silver nanoparticles, secondary metabolites, green chemistry, antibacterial activity.

The gases emissions measurement systems in internal combustion engines are strict and expensive nowadays. For this reason, a virtual instrument was developed to measure the combustion emissions from an internal combustion diesel engine, running with diesel-biodiesel mixtures. This software is called virtual instrument for emissions measurement (VIEM), and it was developed in the platform of LabVIEW 2010® virtual programming. VIEM works with sensors connected to a signal conditioning system, and a data acquisition system is used as interface for a computer in order to measure and monitor in real time the emissions of O₂, NO, CO, SO₂, and CO₂gases. This paper shows the results of the VIEM programming, the integrated circuits diagrams used for the signal conditioning of sensors, and the sensors characterization of O₂, NO, CO, SO₂, and CO₂. VIEM is a low-cost instrument and is simple and easy to use. Besides, it is scalable, making it flexible and defined by the user.