Fundacion Instituto Zuliano Of Investigaciones Tecnologicas

Zulia, Venezuela

Fundacion Instituto Zuliano Of Investigaciones Tecnologicas

Zulia, Venezuela
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Fernandez-Delgado M.,CNR Institute of Biophysics | Duque Z.,Fundacion Instituto Zuliano Of Investigaciones Tecnologicas | Rojas H.,Central University of Venezuela | Suarez P.,Simon Bolivar University of Venezuela | And 3 more authors.
Annals of Microbiology | Year: 2015

Proteus mirabilis is a human pathogen able to form biofilms on the surface of urinary catheters. Little is known about P. mirabilis biofilms on natural or industrial surfaces and the potential consequences for these settings. The main aim of this work was to assess and compare the adhesion and biofilm formation of P. mirabilis strains from different origins on chitin and stainless steel surfaces within 4 to 96 h. Using environmental scanning electron microscopy, the biofilms of a clinical strain grown on chitin at 4 h showed greater adhesion, aggregation, thickness, and extracellular matrix production than those grown on stainless steel, whereas biofilms of an environmental strain had less aggregation on both surfaces. Biofilms of both P. mirabilis strains developed different structures on chitin, such as pillars, mushrooms, channels, and crystalline-like precipitates between 24 and 96 h, in contrast with flat-layer biofilms produced on stainless steel. Significant differences (p < 0.05) were found in the frequency of pillars and channels. Images of transmission electron microscopy demonstrated abundant fimbriae in 100 % of cells from both strains, which could be related to surface adherence and biofilm formation. This represents the first study of P. mirabilis showing adhesion, biofilm formation, and development of different structures on surfaces found outside the human host. © 2014, The Author(s).

Castellanos M.I.,Rafael María Baralt National Experimental University | Duque Z.,Fundacion Instituto Zuliano Of Investigaciones Tecnologicas
Revista de la Facultad de Ingenieria | Year: 2014

The use of the 3003 series aluminum alloys (AA 3003) is diverse in the industrial systems (storage tanks, chemical equipments, among others). This is due to its high resistance to corrosion as a result of passive films developed in presence of oxidizing media. However, there is a lack of evidence to show their behaviour in lacustrine applications in which there is a significant biomass formation. For this reason, the objective of this paper is to describe the behavior of AA 3003 in oxygen-free (reduced) media. To this aim, the material was settled in immersion with anaerobic bacteria cultures, specifically in media containing sulphate-reducing bacteria (SRB) and total heterotrophic facultative bacteria (THFB). Both types of microorganisms came from sessile populations developed on coupons previously immersed in Maracaibo Lake. Electrochemical and microscopic techniques were used for the evaluation of the corrosive behavior. The results indicated that the AA-3003 resistance to corrosion increased over time, in presence of the BHTF and SRB.

Duque Z.,Fundacion Instituto Zuliano Of Investigaciones Tecnologicas | Castillo J.,Fundacion Instituto Zuliano Of Investigaciones Tecnologicas | Mejias G.,Central University of Venezuela | Garcia S.,Central University of Venezuela
Acta Microscopica | Year: 2010

Atmospheric particulate matter PM10, was evaluated using scanning electron microscopy (SEM) coupled to an X-ray Energy Dispersive Spectrometer with the purpose of characterizing the particles taken at a air quality monitoring station located in the populated area of Santa Cruz de Mara, Zulia State, Venezuela. The study included the filters used in the dry and rainy periods of 2008, which found a group of elements associated with sands and potential metals-containing minerals. Likewise, we found a significant difference between the elemental composition of the wet and dry periods, finding in the latter a large number of minor and trace elements. The back trajectories at the mentioned periods highlight the influence upon PM10 particles of the air masses predominantly from the coast of Falcon State, Coro Dunes and Castillete. With this work were able to find the PM10 elemental chemical profile and its variation depending on the weather conditions of the area, analyzing a total of 3151 particles. Finally, the main morphological characteristics of PTS were determined.

Castellanos M.I.,Fundacion Instituto Zuliano Of Investigaciones Tecnologicas | Castellanos M.I.,Rafael María Baralt National Experimental University | Duque Z.,Fundacion Instituto Zuliano Of Investigaciones Tecnologicas
Acta Microscopica | Year: 2013

In natural media the aluminum has high corrosion resistance. However, in saline environments, it has been shown that alloys like 3003 have a high susceptibility to pitting corrosion. Generally, these alloys are susceptible to this type of corrosion by formation of galvanic cells between the intermetallic particles present in the alloy and the aluminum metal matrix. Currently, we have no studies to indicate its behavior in lacustrine media as Maracaibo Lake, which has significant levels of chloride (1300 mg / L) and microbiota promoter of biofouling. Hence there is a concern to assess the potential of Al 3003, available on the domestic industry, and of interest for use in the construction of water transport units for operation in this lake. To this end, in a first phase, biofouling and aggressiveness were studied on the 3003 alloy in laboratory and field conditions, using isolated heterotrophic biomass culture isolated from probes exposed in the Lake. Analyses consisted of microbiological, electrochemical and microscopic techniques. The results indicated that under the studied conditions the Al 3003 showed a tendency to decrease and stabilize the speed and potential of corrosion. The SEM micrographs showed the development of a population in the materials without localized damage. From this an apparent resistance to the conditions evaluated is deduced.

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