Genrry Delgado | Universidad de la Habana (original) (raw)

Papers by Genrry Delgado

Research paper thumbnail of An unusual presentation of chondroid syringoma over nose

Indian Journal of Dermatopathology and Diagnostic Dermatology, 2018

Since plastics degrade very slowly, they remain in the environment on much longer timescales than... more Since plastics degrade very slowly, they remain in the environment on much longer timescales than most natural substrates and can thus provide a novel habitat for colonization by bacterial communities. The full spectrum of relationships between plastics and bacteria, however, is little understood. The objective of this study was to examine marine plastic pollution as a substrate for bacteria, with particular focus on Vibrio spp., including the human pathogens, Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus. Colonization experiments were set up in a tributary of the lower Chesapeake Bay to follow Vibrio spp. colonization and total bacterial community composition over time. Microplastics and paired seawater samples were also collected and examined for the presence and abundance of Vibrio spp. In many instances, vibrios were enriched on plastics by at least two orders of magnitude compared to paired seawater samples. Antibiotic-resistance profiles for Vibrio spp. isolates revealed no differences between the antibiotic susceptibilities of vibrios isolated from plastics compared to those from the surrounding water column. There was, however, a significant difference in antibiotic susceptibility between isolates from colonization experiments and microplastics, with more resistance overall seen in the former. Bacterial colonization on plastics was detected with DNA sequencing as early as day two and communities on plastic were consistently distinct and more diverse than surrounding seawater. Fifteen different bacterial classes were found in water and biofilms and 171 genera were identified. Among all samples, Gammaproteobacteria (30%) constituted the majority of the total sequences with the next most retrieved bacterial classes being Bacteroidetes (28%) and Alphaproteobacteria (20%). Colonization rates and community structure varied temporally and among substrate types, suggesting that numerous factors should be considered when characterizing microbial communities on plastic. This is the first study to culture V. cholerae, V. parahaemolyticus, and V. vulnificus from marine plastics, demonstrates that plastic pollution serves as a habitat for Vibrio species, and confirms the conjecture of Zettler et al. (2013) that plastics may serve as a vector for these and other potentially pathogenic bacteria. Lastly, I am incredibly thankful for Debra Martin, Randy and Donna Laverty, and Traci Johnson-without their continuous support and overflowing love I would not be where I am today. viii

Research paper thumbnail of Thermal analysis of ceramic nuclear fuels for the HPLWR

Annals of Nuclear Energy, 2019

The High Performance Light Water Reactor (HPLWR) is one of the most promising designs of the Supe... more The High Performance Light Water Reactor (HPLWR) is one of the most promising designs of the Super-Critical Water Reactor (SCWR). The use of uranium nitride (UN) and uranium carbide (UC), as alternative nuclear fuels for the SCWR, offer the advantage of high thermal conductivity compared to uranium dioxide (UO 2). For the analysis of these alternative nuclear fuels in SCWRs, some important design features must be considered. One of them is the porosity; the nuclear fuel is manufactured with different porosity values, as high as 20%, to reduce its hardness and swelling, influencing its thermal conductivity. Another issue is related to the chemical reactivity of UN and UC with water and nickel, which forces the use of coatings for fuel pellets. In this paper, a preliminary thermal-hydraulic analysis, using CFD codes, of the HPLWR fuel assembly, focused on the thermal behavior of ceramic fuel, was carried out. The use of UN coated with zirconium carbide layers and UC coated with titanium nitride layers were analyzed. The impact of porosity induced changes in fuel temperature profiles was analyzed. The radial and axial fuel temperature distributions were obtained for all cases. It was found that the maximum temperature values obtained using UN and UC, both coated and uncoated, were lower than those obtained with UO 2. It was found that the porosity changes on the proposed fuels have a small influence on the maximum fuel temperature.

Research paper thumbnail of An unusual presentation of chondroid syringoma over nose

Indian Journal of Dermatopathology and Diagnostic Dermatology, 2018

Since plastics degrade very slowly, they remain in the environment on much longer timescales than... more Since plastics degrade very slowly, they remain in the environment on much longer timescales than most natural substrates and can thus provide a novel habitat for colonization by bacterial communities. The full spectrum of relationships between plastics and bacteria, however, is little understood. The objective of this study was to examine marine plastic pollution as a substrate for bacteria, with particular focus on Vibrio spp., including the human pathogens, Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus. Colonization experiments were set up in a tributary of the lower Chesapeake Bay to follow Vibrio spp. colonization and total bacterial community composition over time. Microplastics and paired seawater samples were also collected and examined for the presence and abundance of Vibrio spp. In many instances, vibrios were enriched on plastics by at least two orders of magnitude compared to paired seawater samples. Antibiotic-resistance profiles for Vibrio spp. isolates revealed no differences between the antibiotic susceptibilities of vibrios isolated from plastics compared to those from the surrounding water column. There was, however, a significant difference in antibiotic susceptibility between isolates from colonization experiments and microplastics, with more resistance overall seen in the former. Bacterial colonization on plastics was detected with DNA sequencing as early as day two and communities on plastic were consistently distinct and more diverse than surrounding seawater. Fifteen different bacterial classes were found in water and biofilms and 171 genera were identified. Among all samples, Gammaproteobacteria (30%) constituted the majority of the total sequences with the next most retrieved bacterial classes being Bacteroidetes (28%) and Alphaproteobacteria (20%). Colonization rates and community structure varied temporally and among substrate types, suggesting that numerous factors should be considered when characterizing microbial communities on plastic. This is the first study to culture V. cholerae, V. parahaemolyticus, and V. vulnificus from marine plastics, demonstrates that plastic pollution serves as a habitat for Vibrio species, and confirms the conjecture of Zettler et al. (2013) that plastics may serve as a vector for these and other potentially pathogenic bacteria. Lastly, I am incredibly thankful for Debra Martin, Randy and Donna Laverty, and Traci Johnson-without their continuous support and overflowing love I would not be where I am today. viii

Research paper thumbnail of Thermal analysis of ceramic nuclear fuels for the HPLWR

Annals of Nuclear Energy, 2019

The High Performance Light Water Reactor (HPLWR) is one of the most promising designs of the Supe... more The High Performance Light Water Reactor (HPLWR) is one of the most promising designs of the Super-Critical Water Reactor (SCWR). The use of uranium nitride (UN) and uranium carbide (UC), as alternative nuclear fuels for the SCWR, offer the advantage of high thermal conductivity compared to uranium dioxide (UO 2). For the analysis of these alternative nuclear fuels in SCWRs, some important design features must be considered. One of them is the porosity; the nuclear fuel is manufactured with different porosity values, as high as 20%, to reduce its hardness and swelling, influencing its thermal conductivity. Another issue is related to the chemical reactivity of UN and UC with water and nickel, which forces the use of coatings for fuel pellets. In this paper, a preliminary thermal-hydraulic analysis, using CFD codes, of the HPLWR fuel assembly, focused on the thermal behavior of ceramic fuel, was carried out. The use of UN coated with zirconium carbide layers and UC coated with titanium nitride layers were analyzed. The impact of porosity induced changes in fuel temperature profiles was analyzed. The radial and axial fuel temperature distributions were obtained for all cases. It was found that the maximum temperature values obtained using UN and UC, both coated and uncoated, were lower than those obtained with UO 2. It was found that the porosity changes on the proposed fuels have a small influence on the maximum fuel temperature.