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Climatological variability of surface particulate organic carbon (POC) and physical processes based on ocean color data in the Gulf of Mexico

  • Son, Young-Baek;Gardner, Wilford D.
    • Korean Journal of Remote Sensing
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    • v.27 no.3
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    • pp.235-258
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    • 2011
  • The purpose of this study is to investigate climatological variations from the temporal and spatial surface particulate organic carbon (POC) estimates based on SeaWiFS spectral radiance, and to determine the physical mechanisms that affect the distribution of pac in the Gulf of Mexico. 7-year monthly mean values of surface pac concentration (Sept. 1997 - Dec. 2004) were estimated from Maximum Normalized Difference Carbon Index (MNDCI) algorithm using SeaWiFS data. Synchronous 7-year monthly mean values of remote sensing data (sea surface temperature (SST), sea surface wind (SSW), sea surface height anomaly (SSHA), precipitation rate (PR)) and recorded river discharge data were used to determine physical forcing factors. The spatial pattern of POC was related to one or more factors such as river runoff, wind-derived current, and stratification of the water column, the energetic Loop Current/Eddies, and buoyancy forcing. The observed seasonal change in the POC plume's response to wind speed in the western delta region resulted from seasonal changes in the upper ocean stratification. During late spring and summer, the low-density river water is heated rapidly at the surface by incoming solar radiation. This lowers the density of the fresh-water plume and increases the near-surface stratification of the water column. In the absence of significant wind forcing, the plume undergoes buoyant spreading and the sediment is maintained at the surface by the shallow pycnocline. However, when the wind speed increases substantially, wind-wave action increases vertical motion, reducing stratification, and the sediment were mixed downward rather than spreading laterally. Maximum particle concentrations over the outer shelf and the upper slope during lower runoff seasons were related to the Loop Current/eddies and buoyancy forcing. Inter-annual differences of POC concentration were related to ENSO cycles. During the El Nino events (1997-1998 and 2002-2004), the higher pac concentrations existed and were related to high runoffs in the eastern Gulf of Mexico, but the opposite conditions in the western Gulf of Mexico. During La Nina conditions (1999-2001), low Poe concentration was related to normal or low river discharge, and low PM/nutrient waters in the eastern Gulf of Mexico, but the opposite conditions in the western Gulf of Mexico.

Differential Effects of Two Widely Used Solvents, DMSO and Ethanol, on the Growth and Recovery of Trypanosoma cruzi Epimastigotes in Culture

  • Cevallos, Ana Maria;Herrera, Juliana;Lopez-Villasenor, Imelda;Hernandez, Roberto
    • The Korean Journal of Parasitology
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    • v.55 no.1
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    • pp.81-84
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    • 2017
  • Trypanosoma cruzi is the etiological agent of Chagas disease. Epimastigote forms of T. cruzi can be readily cultured in axenic conditions. Ethanol and dimethyl sulfoxide (DMSO) are commonly used solvents employed as vehicles for hydrophobic compounds. In order to produce a reference plot of solvent dependent growth inhibition for T. cruzi research, the growth of epimastigotes was analyzed in the presence of different concentrations of ethanol (0.1-4.0%) and DMSO (0.5-7.5%). The ability of the parasites to resume growth after removal of these solvents was also examined. As expected, both ethanol and DMSO produced a dose-dependent inhibition of cellular growth. Parasites could recover normal growth after 9 days in up to 2% ethanol or 5% DMSO. Since DMSO was better tolerated than ethanol, it is thus recommended to prefer DMSO over ethanol in the case of a similar solubility of a given compound.

Molecular Cloning and Characterization of Mannitol-1-Phosphate Dehydrogenase from Vibrio cholerae

  • Rambhatla, Prashanthi;Kumar, Sanath;Floyd, Jared T.;Varela, Manuel F.
    • Journal of Microbiology and Biotechnology
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    • v.21 no.9
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    • pp.914-920
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    • 2011
  • Vibrio cholerae utilizes mannitol through an operon of the phosphoenolpyruvate-dependent phosphotransferase (PTS) type. A gene, mtlD, encoding mannitol-1-phosphate dehydrogenase was identified within the 3.9 kb mannitol operon of V. cholerae. The mtlD gene was cloned from V. cholerae O395, and the recombinant enzyme was functionally expressed in E. coli as a $6{\times}$His-tagged protein and purified to homogeneity. The recombinant protein is a monomer with a molecular mass of 42.35 kDa. The purified recombinant MtlD reduced fructose 6-phosphate (F6P) using NADH as a cofactor with a $K_m$ of $1.54{\pm}0.1$ mM and $V_{max}$ of $320.8{\pm}7.81\;{\mu}mol$/min/mg protein. The pH and temperature optima for F6P reduction were determined to be 7.5 and $37^{\circ}C$, respectively. Using quantitative real-time PCR analysis, mtlD was found to be constitutively expressed in V. cholerae, but the expression was up-regulated when grown in the presence of mannitol. The MtlD expression levels were not significantly different between V. cholerae O1 and non-O1 strains.

The MAK16 Gene of Entamoeba histolytica and Its Identification in Isolates from Patients

  • Crisostomo-Vazquez, Maria del Pilar;Marevelez-Acosta, V?ctor Alberto;Flores-Luna, Andres;Jimenez-Cardoso, Enedina
    • The Korean Journal of Parasitology
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    • v.52 no.4
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    • pp.429-433
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    • 2014
  • To identify sequences of Entamoeba histolytica associated with the development of amebic liver abscess (ALA) in hamsters, subtractive hybridization of cDNA from E. histolytica HM-1:IMSS under 2 growth conditions was performed: 1) cultured in axenic medium and 2) isolated from experimental ALA in hamsters. For this procedure, 6 sequences were obtained. Of these sequences, the mak16 gene was selected for amplification in 29 cultures of E. histolytica isolated from the feces of 10 patients with intestinal symptoms and 19 asymptomatic patients. Only 5 of the 10 isolates obtained from symptomatic patients developed ALA and amplified the mak16 gene, whereas the 19 isolates from asymptomatic patients did not amplify the mak16 gene nor did they develop ALA. Based on the results of Fisher's exact test (P<0.001), an association was inferred between the presence of the mak16 gene of E. histolytica and the ability to develop ALA in hamsters and with the patient's symptoms (P=0.02). The amplification of the mak16 gene suggests that it is an important gene in E. histolytica because it was present in the isolates from hamsters that developed liver damage.

Characterization of recycled polycarbonate from electronic waste and its use in hydraulic concrete: Improvement of compressive performance

  • Colina-Martinez, Ana L. De la;Martinez-Barrera, Gonzalo;Barrera-Diaz, Carlos E.;Avila-Cordoba, Liliana I.;Urena-Nunez, Fernando
    • Advances in concrete construction
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    • v.5 no.6
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    • pp.563-573
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    • 2017
  • Transparency, excellent toughness, thermal stability and a very good dimensional stability make Polycarbonate (PC) one of the most widely used engineering thermoplastics. Polycarbonate market include electronics, automotive, construction, optical media and packaging. One alternative for reducing the environmental pollution caused by polycarbonate from electronic waste (e-waste), is to use it in cement concretes. In this work, physical and chemical characterization of recycled polycarbonate from electronic waste was made, through the analysis by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and scanning electron microscope (SEM). Then cement concrete was made with Portland cement, sand, gravel, water, and this recycled polycarbonate. Specimens without polycarbonate were produced for comparison purposes. The effect of the particle sizes and concentrations of recycled polycarbonate within the concrete, on the compressive strength and density was studied. Results show that compressive strength values and equilibrium density of concrete depend on the polycarbonate particle sizes and its concentrations; particularly the highest compressive strength values were 20% higher than that for concrete without polycarbonate particles. Moreover, morphological, structural and crystallinity characteristics of recycled polycarbonate, are suitable for to be mixed into concrete.

Photonic sensors for micro-damage detection: A proof of concept using numerical simulation

  • Sheyka, M.;El-Kady, I.;Su, M.F.;Taha, M.M. Reda
    • Smart Structures and Systems
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    • v.5 no.4
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    • pp.483-494
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    • 2009
  • Damage detection has been proven to be a challenging task in structural health monitoring (SHM) due to the fact that damage cannot be measured. The difficulty associated with damage detection is related to electing a feature that is sensitive to damage occurrence and evolution. This difficulty increases as the damage size decreases limiting the ability to detect damage occurrence at the micron and submicron length scale. Damage detection at this length scale is of interest for sensitive structures such as aircrafts and nuclear facilities. In this paper a new photonic sensor based on photonic crystal (PhC) technology that can be synthesized at the nanoscale is introduced. PhCs are synthetic materials that are capable of controlling light propagation by creating a photonic bandgap where light is forbidden to propagate. The interesting feature of PhC is that its photonic signature is strongly tied to its microstructure periodicity. This study demonstrates that when a PhC sensor adhered to polymer substrate experiences micron or submicron damage, it will experience changes in its microstructural periodicity thereby creating a photonic signature that can be related to damage severity. This concept is validated here using a three-dimensional integrated numerical simulation.

Sustainable Development of Palm Oil: Synthesis and Electrochemical Performance of Corrosion Inhibitors

  • Porcayo-Calderon, J.;Rivera-Munoz, E.M.;Peza-Ledesma, C.;Casales-Diaz, M.;de la Escalera, L.M. Martinez;Canto, J.;Martinez-Gomez, L.
    • Journal of Electrochemical Science and Technology
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    • v.8 no.2
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    • pp.133-145
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    • 2017
  • Palm oil production is among the highest worldwide, and it has been mainly used in the food industry and other commodities. Currently, a lot of palm oil production has been destined for the synthesis of biodiesel; however, its use in applications other than the food industry has been questioned. Thereby for a sustainable development, in this paper the use of palm oil of low quality for corrosion inhibitors synthesis is proposed. The performance of the synthesized inhibitors was evaluated by using electrochemical techniques such as open circuit potential measurements, linear polarization resistance and electrochemical impedance spectroscopy. The results indicate that the fatty amides from palm oil are excellent corrosion inhibitors with protection efficiencies greater than 98%. Fatty amides molecules act as cathodic inhibitors decreasing the anodic dissolution of iron. When fatty amides are added, a rapid decrease in the corrosion rate occurs due to the rapid formation of a molecular film onto carbon steel surface. During the adsorption process of the inhibitor a self-organization of the hydrocarbon chains takes place forming a tightly packed hydrophobic film. These results demonstrate that the use of palm oil for the production of green inhibitors promises to be an excellent alternative for a sustainable use of the palm oil production.

Identification of Mycobacterium leprae and Mycobacterium lepromatosis in Formalin-Fixed and Paraffin-Embedded Skin Samples from Mexico

  • Torres-Guerrero, Edoardo;Sanchez-Moreno, Elisa Crystal;Atoche-Dieguez, Carlos Enrique;Carrillo-Casas, Erika Margarita;Arenas, Roberto;Xicohtencatl-Cortes, Juan;Hernandez-Castro, Rigoberto
    • Annals of dermatology
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    • v.30 no.5
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    • pp.562-565
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    • 2018
  • Background: The causative agents of leprosy are the well-known Mycobacterium leprae and the newly discovered Mycobacterium lepromatosis. This agent was found in 2008, and it was found to be the cause of diffuse lepromatous leprosy in two Mexican patients. Objective: The objective of this work was to determine if M. leprae and M. lepromatosis were present in formalin-fixed and paraffin-embedded skin samples from cases from different regions in Mexico. Methods: A total of 41 skin samples were obtained from 11 states of Mexico. All patients' samples were diagnosed by clinical and histopathological analyses. Total DNA was isolated using a Qiagen-DNeasy blood and tissue kit and molecular identification was achieved by two semi-nested polymerase chain reactions. Results: The 41 patient included 33 samples from men and 8 samples from women; 29 samples were polymerase chain reaction (PCR)-positive to Mycobacterium and 12 samples were PCR-negative. From those 29 samples, 13 were PCR-positive to M. leprae, 8 to M. lepromatosis and 8 were positive to both species. The histopathological diagnosis included; Nodular lepromatous leprosy (NLL); Diffuse lepromatous leprosy (DLL); and Borderline leprosy (BL). The 29 PCR-positive samples were classified as follow: 14 NLL, 4 DLL, and 11 BL. In the 12 samples negative to Mycobacterium, 7 showed the NLL, 2 DLL and 3 BL. Conclusion: These findings add evidence to the M. leprae and M. lepromatous distribution, clinical forms and participation of dual infections in Mexico.

Pharmacokinetics of enrofloxacin HCl-2H2O (Enro-C) in dogs and pharmacokinetic/pharmacodynamic Monte Carlo simulations against Leptospira spp.

  • Sumano, Hector;Ocampo, Luis;Tapia, Graciela;de Jesus Mendoza, Corazon;Gutierrez, Lilia
    • Journal of Veterinary Science
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    • v.19 no.5
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    • pp.600-607
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    • 2018
  • Pharmacokinetic/pharmacodynamic (PK/PD) ratios of reference enrofloxacin (Enro-R) and enrofloxacin as $HCl-2H_2O$ (Enro-C), as well as Monte Carlo simulations based on composite $MIC_{50}$ and $MIC_{90}$ (MIC, minimum inhibitory concentration) vs. Leptospira spp., were carried out in dogs after their intramuscular (IM) or oral administration (10 mg/kg). Plasma determination of enrofloxacin was achieved by means of high-performance liquid chromatography. Maximum plasma concentration values after oral administration were $1.47{\pm}0.19{\mu}g/mL$ and $5.3{\pm}0.84{\mu}g/mL$ for Enro-R and Enro-C, respectively, and $1.6{\pm}0.12{\mu}g/mL$ and $7.6{\pm}0.93{\mu}g/mL$, respectively, after IM administration. Areas under the plasma vs. time concentration curve in 24 h ($AUC_{0-24}$) were $8.02{\mu}g/mL/h$ and $36.2{\mu}g/mL/h$ for $Enro-R_{oral}$ and $Enro-C_{oral}$, respectively, and $8.55{\pm}0.85{\mu}g/mL/h$ and $56.4{\pm}6.21{\mu}g/mL/h$ after IM administration of Enro-R and Enro-C, respectively. The PK/PD ratios and Monte Carlo simulations obtained with Enro-C, not Enro-R, indicated that its IM administration to dogs will result in therapeutic concentrations appropriate for treating leptospirosis. This is the first time enrofloxacin has been recommended to treat this disease in dogs.