109 results on '"Torres, F."'
Search Results
2. KLD: a program to elucidate the localization of the Fermi and Coulomb holes in molecular systems.
- Author
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Bedoya, Valeria, Rodríguez, Vladimir, Rincón, Luis, Zambrano, Cesar, Seijas, Luis, and Torres, F. Javier
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MOLECULAR orbitals ,NATURAL orbitals ,ELECTRON pairs ,CHEMICAL properties ,COMPUTER software development - Abstract
Context: The electron localization is a concept that allows scientists to better understand the physical and chemical properties of electronic systems. It is associated with the propensity of electron pairs with opposite spins to accumulate as well as with their response to external perturbations. This paper contains a detailed description of the design and implementation of the program KLD, which was primarily developed in our research group to elucidate electron localization in molecular systems by evaluating the information content of electron-pair density functions. KLD employs two information-based functions as a real space measure of the Fermi and Coulomb holes for same-spin electrons and shows a better resolution as compared to other methods (i.e., ELF). Information about the acceleration of the code is also included in the present work, being noticeable the reduction of wall-time calculation and the error calculation between versions. Methods: KLD was designed to be easy to use, extend, and maintain; thus, many principles of modern software development, extensive testing, and package management were adopted. The latest version of the KLD program was created utilizing the Compute Unified Device Architecture (CUDA) version, which allows it to use the computational capacity of NVIDIA Graphics Processing Units (GPUs) for processing purposes. The electron-pair conditional density was calculated from the canonical molecular orbitals obtained at the HF/6-31G(2df,p) level, or alternatively the natural orbitals in the case of explicit correlated wavefunctions computed at the MP2/6-31G(2df,p)//HF/6-31G(2df,p) level. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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3. Multi-Wafer Growth Simultaneously on Four 6 cm × 6 cm CdZnTe Substrates for Step Increase in MBE HgCdTe Wafer Production.
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Reddy, M., Peterson, J. M., Torres, F., Fennel, B. T., Jin, X., Doyle, K., Vang, T., Juanko, N., Johnson, S. M., and Hampp, A.
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FOCAL plane arrays sensors ,MOLECULAR beam epitaxy - Abstract
Molecular beam epitaxy (MBE)-grown HgCdTe on CdZnTe substrates produced the best performing infrared focal plane arrays for both terrestrial and space-based applications. Current practice is limited to growing one HgCdTe wafer per MBE run for substrate sizes ≥ 5 cm × 5 cm. This paper describes the successful implementation of multi-wafer growth on four 6 cm × 6 cm CdZnTe substrates simultaneously, using cost-effective and innovative processes. To demonstrate the efficacy of the process, a relatively hard-to-grow layer structure, namely a LWIR/LWIR dual-band layer structure, was chosen. Growth conditions were optimized using HgCdTe on an 8-inch (c. 20-cm) Si process to achieve a phenomenal HgCdTe cutoff and thickness uniformity of 1.2% and 1.8%, respectively. The results indicate a 4-fold increase in wafer yield while maintaining the values of key characteristics, such as macro-defect density, cutoff wavelength, and thickness, the same as those of single-wafer growth. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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4. Utility of the combination of hederagenin glucoside saponins and chromane hydrazone in the topical treatment of canine cutaneous leishmaniasis. An observational study.
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Piragauta, S. P., Higuita-Castro, J. L., Arbeláez, N., Restrepo, A. M., Archbold, R., Quiñones, W., Torres, F., Echeverri, F., Escobar, G., Vélez, I. D., Montoya, A., and Robledo, S. M.
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CUTANEOUS leishmaniasis ,SAPONINS ,EMERGING infectious diseases ,ENDEMIC diseases ,SCIENTIFIC observation ,SKIN absorption ,TREATMENT effectiveness - Abstract
Canine cutaneous leishmaniasis (CCL) is an emerging zoonotic infection endemic in several countries of the world. Due to variable response to therapy and frequency of relapses, a more effective, safer, and inexpensive treatment is needed. Recently, it was reported that the hederagenin glucoside saponins (SS) and chromane-derived hydrazone (TC2) combined in a 1:1 ratio has high potential in antileishmanial therapy since both compounds alter the survival of Leishmania and the ability to infect adjacent macrophage. Not only the skin permeation and the absorption of an ointment containing 2% TC2 and 2% SS (w/w) was determined in this work, but also the acute dermal toxicity in both in vitro and in vivo assays. Last, the effectiveness and safety of the topical therapy with 2% TC2–2% SS ointment was evaluated in an observational study in dogs with diagnosis of cutaneous leishmaniasis (CL). Both TC2 and SS diffused through pig ear skin and traces of TC2 (but not SS) were detected in the stratum corneum of mice at 6–24 h. Neither TC2 nor SS was detected in plasma. The acute dermal toxicity was negative. Treatment with 2% TC2–2% SS ointment produced a complete long-term clinical cure in 56 dogs (24 females and 32 males) from the Orinoco and Amazonas regions in southeastern Colombia without adverse effects. All dogs have remained disease-free for the last 24 months. In conclusion, these results support the use of this topical therapy as a safer and new first-line local treatment of CCL that could help limit the spread of CL from dogs to humans. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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5. Removal of mercury(II) from aqueous solution by partially reduced graphene oxide.
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Tene, Talia, Arias Arias, Fabian, Guevara, Marco, Nuñez, Adriana, Villamagua, Luis, Tapia, Carlos, Pisarra, Michele, Torres, F. Javier, Caputi, Lorenzo S., and Vacacela Gomez, Cristian
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MERCURY ,GRAPHENE oxide ,AQUEOUS solutions ,WATER purification ,GRAPHENE ,DENSITY functional theory ,ECOSYSTEM health - Abstract
Mercury (Hg(II)) has been classified as a pollutant and its removal from aqueous sources is considered a priority for public health as well as ecosystem protection policies. Oxidized graphenes have attracted vast interest in water purification and wastewater treatment. In this report, a partially reduced graphene oxide is proposed as a pristine adsorbent material for Hg(II) removal. The proposed material exhibits a high saturation Hg(II) uptake capacity of 110.21 mg g
−1 , and can effectively reduce the Hg(II) concentration from 150 mg L−1 to concentrations smaller than 40 mg L−1 , with an efficiency of about 75% within 20 min. The adsorption of Hg(II) on reduced graphene oxide shows a mixed physisorption–chemisorption process. Density functional theory calculations confirm that Hg atom adsorbs preferentially on clean zones rather than locations containing oxygen functional groups. The present work, therefore, presents new findings for Hg(II) adsorbent materials based on partially reduced graphene oxide, providing a new perspective for removing Hg(II). [ABSTRACT FROM AUTHOR]- Published
- 2022
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6. A Hybrid Statistical-Dynamical Downscaling of Air Temperature over Scandinavia Using the WRF Model
- Author
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Wang, Jianfeng, Fonseca, Ricardo M., Rutledge, Kendall, Martín-Torres, F. J., Yu, Jun, Wang, Jianfeng, Fonseca, Ricardo M., Rutledge, Kendall, Martín-Torres, F. J., and Yu, Jun
- Abstract
An accurate simulation of air temperature at local scales is crucial for the vast majority of weather and climate applications. In this work, a hybrid statistical–dynamical downscaling method and a high-resolution dynamical-only downscaling method are applied to daily mean, minimum and maximum air temperatures to investigate the quality of localscale estimates produced by downscaling. These two downscaling approaches are evaluated using station observation data obtained from the Finnish Meteorological Institute over a near-coastal region of western Finland. The dynamical downscaling is performed with the Weather Research and Forecasting (WRF) model, and the statistical downscaling method implemented is the Cumulative Distribution Function-transform (CDF-t). The CDF-t is trained using 20 years of WRF-downscaled Climate Forecast System Reanalysis data over the region at a 3-km spatial resolution for the central month of each season. The performance of the two methods is assessed qualitatively, by inspection of quantile-quantile plots, and quantitatively, through the Cramer-von Mises, mean absolute error, and root-mean-square error diagnostics. The hybrid approach is found to provide significantly more skillful forecasts of the observed daily mean and maximum air temperatures than those of the dynamical-only downscaling (for all seasons). The hybrid method proves to be less computationally expensive, and also to give more skillful temperature forecasts (at least for the Finnish near-coastal region).
- Published
- 2019
7. Sample Collection and Return from Mars: Optimising Sample Collection Based on the Microbial Ecology of Terrestrial Volcanic Environments
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Science and Technology Facilities Council (UK), Cockell, Charles S., McMahon, Sean, Lim, Darlene, Rummel, John, Stevens, Adam, Hughes, S. S., Kobs Nawotniak, S. E., Brady, A. L., Marteinsson, Viggó, Martín-Torres, F. J., Zorzano, María Paz, Harrison, Jesse, Science and Technology Facilities Council (UK), Cockell, Charles S., McMahon, Sean, Lim, Darlene, Rummel, John, Stevens, Adam, Hughes, S. S., Kobs Nawotniak, S. E., Brady, A. L., Marteinsson, Viggó, Martín-Torres, F. J., Zorzano, María Paz, and Harrison, Jesse
- Abstract
With no large-scale granitic continental crust, all environments on Mars are fundamentally derived from basaltic sources or, in the case of environments such as ices, evaporitic, and sedimentary deposits, influenced by the composition of the volcanic crust. Therefore, the selection of samples on Mars by robots and humans for investigating habitability or testing for the presence of life should be guided by our understanding of the microbial ecology of volcanic terrains on the Earth. In this paper, we discuss the microbial ecology of volcanic rocks and hydrothermal systems on the Earth. We draw on microbiological investigations of volcanic environments accomplished both by microbiology-focused studies and Mars analog studies such as the NASA BASALT project. A synthesis of these data emphasises a number of common patterns that include: (1) the heterogeneous distribution of biomass and diversity in all studied materials, (2) physical, chemical, and biological factors that can cause heterogeneous microbial biomass and diversity from sub-millimetre scales to kilometre scales, (3) the difficulty of a priori prediction of which organisms will colonise given materials, and (4) the potential for samples that are habitable, but contain no evidence of a biota. From these observations, we suggest an idealised strategy for sample collection. It includes: (1) collection of multiple samples in any given material type (similar to 9 or more samples), (2) collection of a coherent sample of sufficient size (similar to 10 cm(3)) that takes into account observed heterogeneities in microbial distribution in these materials on Earth, and (3) collection of multiple sample suites in the same material across large spatial scales. We suggest that a microbial ecology-driven strategy for investigating the habitability and presence of life on Mars is likely to yield the most promising sample set of the greatest use to the largest number of astrobiologists and planetary scientists.
- Published
- 2019
8. High-resolution dynamical downscaling of re-analysis data over the Kerguelen Islands using the WRF model
- Author
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Swedish National Infrastructure for Computing, Fonseca, Ricardo, Martín-Torres, F. J., Swedish National Infrastructure for Computing, Fonseca, Ricardo, and Martín-Torres, F. J.
- Abstract
We have used the Weather Research and Forecasting (WRF) model to simulate the climate of the Kerguelen Islands (49° S, 69° E) and investigate its inter-annual variability. Here, we have dynamically downscaled 30 years of the Climate Forecast System Reanalysis (CFSR) over these islands at 3-km horizontal resolution. The model output is found to agree well with the station and radiosonde data at the Port-aux-Français station, the only location in the islands for which observational data is available. An analysis of the seasonal mean WRF data showed a general increase in precipitation and decrease in temperature with elevation. The largest seasonal rainfall amounts occur at the highest elevations of the Cook Ice Cap in winter where the summer mean temperature is around 0 °C. Five modes of variability are considered: conventional and Modoki El Niño-Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), Subtropical IOD (SIOD) and Southern Annular Mode (SAM). It is concluded that a key mechanism by which these modes impact the local climate is through interaction with the diurnal cycle in particular in the summer season when it has a larger magnitude. One of the most affected regions is the area just to the east of the Cook Ice Cap extending into the lower elevations between the Gallieni and Courbet Peninsulas. The WRF simulation shows that despite the small annual variability, the atmospheric flow in the Kerguelen Islands is rather complex which may also be the case for the other islands located in the Southern Hemisphere at similar latitudes.
- Published
- 2019
9. Aeolian transport of viable microbial life across the Atacama Desert, Chile: Implications for Mars
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European Research Council, Azua-Bustos, Armando, González-Silva, Carlos, Fernández-Martínez, M. A., Arenas Fajardo, Cristián, Fonseca, Ricardo, Martín-Torres, F. J., Fernández Sampedro, Maite, Fairén, Alberto G., Zorzano, María Paz, European Research Council, Azua-Bustos, Armando, González-Silva, Carlos, Fernández-Martínez, M. A., Arenas Fajardo, Cristián, Fonseca, Ricardo, Martín-Torres, F. J., Fernández Sampedro, Maite, Fairén, Alberto G., and Zorzano, María Paz
- Abstract
Here we inspect whether microbial life may disperse using dust transported by wind in the Atacama Desert in northern Chile, a well-known Mars analog model. By setting a simple experiment across the hyperarid core of the Atacama we found that a number of viable bacteria and fungi are in fact able to traverse the driest and most UV irradiated desert on Earth unscathed using wind-transported dust, particularly in the later afternoon hours. This finding suggests that microbial life on Mars, extant or past, may have similarly benefited from aeolian transport to move across the planet and find suitable habitats to thrive and evolve.
- Published
- 2019
10. The challenges and possibilities of earthquake predictions using non-seismic precursors.
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Bhardwaj, A., Sam, L., and Martin-Torres, F. J.
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EARTHQUAKE prediction ,LAND surface temperature ,GRAVITY waves ,ATMOSPHERIC waves ,ANIMAL behavior ,TROPOSPHERIC chemistry ,ATMOSPHERIC electricity - Abstract
The catastrophic magnitude of life and monetary losses associated with earthquakes deserve serious attention and mitigation measures. However, in addition to the pre-earthquake and post-earthquake alleviation actions, the scientific community indeed needs to reconsider the possibilities of earthquake predictions using non-seismic precursors. A significant number of studies in the recent decades have reported several possible earthquake precursors such as anomalies in electric field, magnetic field, gas/aerosol emissions, ionospheric signals, ground water level, land surface temperature, surface deformations, animal behaviour, thermal infrared signals, atmospheric gravity waves, and lightning. Such substantial number of scientific articles and reported anomalous signals cannot be overlooked without a thoughtful appraisal. Here, we provide an opinion on the way forward for earthquake prediction in terms of challenges and possibilities while using non-seismic precursors. A general point of concern is the widely varying arrival times and the amplitudes of the anomalies, putting a question mark on their universal applicability as earthquake markers. However, a unifying concept which does not only define the physical basis of either all or most of these anomalies but which also streamlines their characterisation procedure must be the focus of future earthquake precursory research. Advancements in developing the adaptable instrumentation for in-situ observations of the claimed non-seismic precursors must be the next step and the satellite observations should not be taken as a replacement for field-based research. We support the need to standardise the precursor detection techniques and to employ a global-scale monitoring system for making any possible earthquake predictions reliable. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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11. When global and local molecular descriptors are more than the sum of its parts: Simple, But Not Simpler?
- Author
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Martínez-López, Yoan, Marrero-Ponce, Yovani, Barigye, Stephen J., Teran, Enrique, Martínez-Santiago, Oscar, Zambrano, Cesar H., and Torres, F. Javier
- Abstract
In this report, we introduce a set of aggregation operators (AOs) to calculate global and local (group and atom type) molecular descriptors (MDs) as a generalization of the classical approach of molecular encoding using the sum of the atomic (or fragment) contributions. These AOs are implemented in a new and free software denominated MD-LOVIs (http://tomocomd.com/md-lovis), which allows for the calculation of MDs from atomic weights vector and LOVIs (local vertex invariants). This software was developed in Java programming language and employed the Chemical Development Kit (CDK) library for handling chemical structures and the calculation of atomic weights. An analysis of the complexities of the algorithms presented herein demonstrates that these aspects were efficiently implemented. The calculation speed experiments show that the MD-LOVIs software has satisfactory behavior when compared to software such as Padel, CDKDescriptor, DRAGON and Bluecal software. Shannon's entropy (SE)-based variability studies demonstrate that MD-LOVIs yields indices with greater information content when compared to those of popular academic and commercial software. A principal component analysis reveals that our approach captures chemical information orthogonal to that codified by the DRAGON, Padel and Mold2 software, as a result of the several generalizations in MD-LOVIs not used in other programs. Lastly, three QSARs were built using multiple linear regression with genetic algorithms, and the statistical parameters of these models demonstrate that the MD-LOVIs indices obtained with AOs yield better performance than those obtained when the summation operator is used exclusively. Moreover, it is also revealed that the MD-LOVIs indices yield models with comparable to superior performance when compared to other QSAR methodologies reported in the literature, despite their simplicity. The studies performed herein collectively demonstrated that MD-LOVIs software generates indices as simple as possible, but not simpler and that use of AOs enhances the diversity of the chemical information codified, which consequently improves the performance of traditional MDs. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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12. Modulation of CYP2E1 metabolic activity in a cohort of confirmed caffeine ingesting pregnant women with preterm offspring.
- Author
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Alcorta-García, M. R., López-Villaseñor, C. N., Sánchez-Ferrer, G., Flores-Mendoza, H., Castorena-Torres, F., Aguilar-Torres, M. A., Sepúlveda-Treviño, C. M., Hernández-Hernández, J. A., López-Sánchez, R. C., and Lara-Díaz, V. J.
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PREGNANT women ,CAFFEINE ,CYTOCHROME P-450 ,PREMATURE labor ,COLA drinks ,MEXICANS - Abstract
Background: To ascertain interactions of caffeine ingestion, food, medications, and environmental exposures during preterm human gestation, under informed consent, we studied a cohort of Mexican women with further preterm offspring born at ≤ 34 completed weeks. At birth, blood samples were taken from mothers and umbilical cords to determine caffeine and metabolites concentrations and CYP1A2 (rs762551) and CYP2E1 (rs2031920, rs3813867) polymorphisms involved in caffeine metabolism. Results: In 90 pregnant women who gave birth to 98 preterm neonates, self-informed caffeine ingestion rate was 97%, laboratory confirmed rate was 93 %. Theobromine was the predominant metabolite found. Consumption of acetaminophen correlated significantly with changes in caffeine metabolism (acetaminophen R
2 = 0.637, p = 0.01) due to activation of CYP2E1 alternate pathways. The main caffeine source was cola soft drinks. Conclusion: Environmental exposures, especially acetaminophen ingestion during human preterm pregnancy, can modulate CYP2E1 metabolic activity. [ABSTRACT FROM AUTHOR]- Published
- 2020
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13. A valence bond perspective of the reaction force formalism.
- Author
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Rincon, Luis, Torres, F. Javier, Mora, Jose R., Zambrano, Cesar H., and Rodriguez, Vladimir
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REACTION forces , *DELOCALIZATION energy , *VALENCE bonds , *MECHANICAL energy , *QUANTUM mechanics , *CHEMICAL bonds - Abstract
The reaction force formalism represents a convenient approach to analyze the course of a reaction step. From this analysis, the reaction path can be separated in a number of regions that are associated to either structural changes or electronic reorganization. This empirical observation is rationalized in this work on the basis of a simple two-state valence bond correlation diagram. We demonstrate that the ratio between the integrated reaction force and the region of interest ( w ii / w i for the forward reaction and w iii / w iv for the backward reaction) increases with the ratio between the quantum mechanical resonance energy and the energy required to reach the crossing point at the transition state, we call to this ratio the strength of the resonance. This observation means that the size of the transition region (region ii and iii), that includes the transition state, depends on the strength of the resonance, and the structural zones (region i and iv), that are regions associated with the pure valence bond state curves (no resonance). We propose a simple analytical relationship for w ii / w i and w iii / w iv based on three parameters: (i) the quantum mechanical resonance energy, (ii) the energy of the reaction and (iii) the overlap between the VB structures at the transition state. The previous conclusions were supported by a reaction force analysis of a S N 2 reactions, X - + CH 3 - Y → X - CH 3 + Y - (X = F , Cl , Br) . The valence bond parameters for these reactions are estimated from empirical considerations. A very good agreement is found between the computed reaction force ratios and the predicted one. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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14. Nonlinear multi-element interactions in an elastically coupled microcantilever array subject to electrodynamic excitation.
- Author
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Kambali, P. N., Torres, F., Barniol, N., and Gottlieb, O.
- Abstract
In this work, we formulate and investigate a nonlinear initial boundary-value problem for an array of N elastically coupled hybrid microcantilever beams that are subject to electrodynamic excitation. The equations of motion for the individual viscoelastic element consist of two fields: the base component which is common to all cantilevers and the unrestrained component which is excited electrodynamically. The coupling of the elements is obtained via an equivalent linear stiffness that is estimated from experimental measurements of a 5-element array. We employ a Galerkin ansatz to obtain a modal dynamical system that consistently incorporates a quintic nonlinearity due to the combined effects of cubic viscoelasticity and quadratic electrodynamics. We validate the periodic response of a 5-element array with moderate damping and construct numerically a comprehensive bifurcation structure for a 25-element array. The analysis reveals an intricate structure for small damping that includes both quasiperiodic and nonstationary chaotic-like energy transfer between the elements of the array. It is noteworthy that an array with a larger coupling stiffness, corresponding to a smaller distance between adjacent elements, yields a chaotic bifurcation structure for a larger value of viscoelastic damping. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
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15. Green Composite Materials from Biopolymers Reinforced with Agroforestry Waste.
- Author
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Torres, F. G., Rodriguez, Sol, and Saavedra, A. C.
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COMPOSITE materials ,AGROFORESTRY ,SUSTAINABLE development ,REFUSE containers ,POLYESTERS ,POLYMERIC nanocomposites - Abstract
Environmental concerns have triggered the development of green composites as a replacement of non-degradable polymers. A variety of biopolymers, including polysaccharides, polyesters and proteins are reported to be used as matrices. Such biopolymers feature low mechanical and thermic properties. In order to improve the properties of these biopolymeric matrices, organic fillers derived from agroforestry wastes can be used. This paper aims to provide an up-to-date review of the development of fully green composite materials. A systematical classification based on the chemical structure of the biopolymeric matrices and the morphology of the natural reinforcements is proposed. In most cases, treatments and additives are used to prepare these green composites and overcome the problems related to poor biopolymer-filler interaction. Several applications as well as the improved mechanical, thermic and barrier properties of various green composite are also discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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16. Demonstration of High-Quality MBE HgCdTe on 8-Inch Wafers.
- Author
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Reddy, M., Jin, X., Lofgreen, D. D., Franklin, J. A., Peterson, J. M., Vang, T., Juanko, N., Torres, F., Doyle, K., Hampp, A., Johnson, S. M., and Bangs, J. W.
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ARSENIC - Abstract
High-quality mid-wave infrared (MWIR) double-layer heterojunction HgCdTe has been grown on 8-inch Si substrates using molecular beam epitaxy. We grew six 8-inch-diameter MWIR HgCdTe wafers on Si substrates and measured within-wafer and wafer-to-wafer variations of key parameters such as cutoff wavelength, HgCdTe thickness, macrodefect density including voids and microvoids, and arsenic doping uniformity. The results indicate that the growth was very successful and the process repeatable, well controlled, and ready for production. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
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17. New records of ticks infesting bats in Brazil, with observations on the first nymphal stage of Ornithodoros hasei.
- Author
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Muñoz-Leal, S., Barbier, E., Soares, F. A. M., Bernard, E., Labruna, M. B., and Dantas-Torres, F.
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TICKS ,BATS ,TICK infestations ,ORNITHODOROS ,NYMPHS (Insects) - Abstract
In Brazil, at least 14 species of soft ticks (Argasidae) are associated with bats. While Ornithodoros hasei seems to be abundant among foliage-roosting bats, other groups of ticks are found exclusively inside caves. In this paper, noteworthy records of soft ticks infesting bats are documented in new localities from Bahia, Pernambuco, Piauí, and Rondônia states. Out of 201 bats examined, 25 were infested by 152 ticks belonging to seven taxa: Ornithodoros cavernicolous, O. hasei, Ornithodoros marinkellei, Ornithodoros cf. fonsecai, Ornithodoros cf. clarki, Antricola sp., and Nothoaspis amazoniensis. These findings provide new insights into the geographical distribution and host association of soft ticks occurring in the Neotropical region. Remarkably, morphological and biological observations about O. hasei are inferred based on the examination of on-host-collected first stage nymphs. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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18. On the trajectory tracking control for an SCARA robot manipulator in a fractional model driven by induction motors with PSO tuning.
- Author
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Coronel-Escamilla, A., Torres, F., Gómez-Aguilar, J. F., Escobar-Jiménez, R. F., and Guerrero-Ramírez, G. V.
- Abstract
This paper describes the fractional modeling and control of an industrial selective compliant assembly robot arm (SCARA); the fractional model was obtained by using the Euler-Lagrange and Hamilton formalisms. Each joint of the robot manipulator was driven by an induction motor. In this work, the fractional model of each induction motor was formulated, and the matching of the induction motors with the SCARA robot is shown. For comparison purposes, the SCARA robot control was formulated by conventional PI and PD and by fractional PI
ς and PDδ controllers. So each induction motor was controlled by using PI and fractional PIς controllers, and for trajectory tracking control, PD and fractional PDδ controllers were designed. For tuning the PI, PIς , PD, and PDδ controllers, the PSO algorithm was used; the same restrictions were used for the PI and PD classical controllers, and ITAE index was used as a cost function to be minimized. For computing the fractional derivatives and to obtain the numerical solution of the system, the Riemann-Liouville and Grünwald-Letnikov approaches were used. The numerical simulations have shown the effectiveness of the use of fractional PIς and PDδ controllers. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
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19. Lower tier toxicity risk assessment of agriculture pesticides detected on the Río Madre de Dios watershed, Costa Rica.
- Author
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Mena Torres, F, Ugalde, R, Grandas, L, Ruepert, C, Castillo, L E, Arias-Andrés, M, Rämö, R, Gunnarsson, J S, and Van den Brink, P J
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PESTICIDE toxicology measurement ,TOXICITY testing ,PESTICIDE pollution ,ENVIRONMENTAL risk assessment ,ENVIRONMENTAL toxicology ,WATERSHEDS - Abstract
Costa Rica is a tropical country with one of the highest biodiversity on Earth. It also has an intensive agriculture, and pesticide runoff from banana and pineapple plantations may cause a high toxicity risk to non-target species in rivers downstream the plantations. We performed a first tier risk assessment of the maximum measured concentrations of 32 pesticides detected over 4 years in the River Madre de Dios (RMD) and its coastal lagoon on the Caribbean coast of Costa Rica. Species sensitivity distributions (SSDs) were plotted in order to derive HC
5 values for each pesticide, i.e., hazard concentrations for 5 % of the species, often used as environmental criteria values in other countries. We also carried out toxicity tests for selected pesticides with native Costa Rican species in order to calculate risk coefficients according to national guidelines in Costa Rica. The concentrations of herbicides diuron and ametryn and insecticides carbofuran, diazinon, and ethoprophos exceeded either the HC5 value or the lower limit of its 90 % confidence interval suggesting toxic risks above accepted levels. Risk coefficients of diuron and carbofuran derived using local guidelines indicate toxicity risks as well. The assessed fungicides did not present acute toxic risks according to our analysis. Overall, these results show a possible toxicity of detected pesticides to aquatic organisms and provide a comparison of Costa Rican national guidelines with more refined methods for risk assessment based on SSDs. Further higher tier risk assessments of pesticides in this watershed are also necessary in order to consider pesticide water concentrations over time, toxicity from pesticide mixtures, and eventual effects on ecosystem functions. [ABSTRACT FROM AUTHOR]- Published
- 2018
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20. Theoretical analysis of C-F bond cleavage mediated by cob[I]alamin-based structures.
- Author
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Cortés-Arriagada, D., Toro-Labbe, A., Mora, J., Rincón, L., Mereau, R., and Torres, F.
- Subjects
SCISSION (Chemistry) ,VITAMIN B12 ,MOLECULAR structure ,HALOCARBONS ,DEHALOGENATION - Abstract
In the present work, C-F bond cleavage mediated by the super-reduced form of cobalamin (i.e., CoCbl) was theoretically studied at the ONIOM(BP86/6-311++G(d,p):PM6) + SMD level of theory. Dispersion effects were introduced by employing Grimme's empirical dispersion at the ONIOM(BP86-D/6-311++G(d,p):PM6) + SMD level. In the first stage of the study, cobalamin was characterized in terms of the coordination number of the central cobalt atom. The ONIOM(BP86/6-311++G(d,p):PM6) results showed that the base-off form of the system is slightly more stable than its base-on counterpart (Δ E = E - E ~ −2 kcal/mol). The inclusion of dispersive forces in the description of the system stabilizes the base-on form, which becomes as stable as its base-off counterpart. Moreover, in the latter case, the energy barrier separating both structures was found to be negligible, with a computed value of 1.02 kcal/mol. In the second stage of the work, the reaction CoCbl + CHF → MeCbl + F was studied considering the base-off and the base-on forms of CoCbl. The reaction that occurs in the presence of the base-on form of CoCbl was found to be kinetically more favorable (Δ E = 13.7 kcal/mol) than that occurring in the presence of the base-off form (Δ E = 41.2 kcal/mol). Further reaction-force analyses of the processes showed that the energy barrier to C-F bond cleavage arises largely due to structural rearrangements when the reaction occurs on the base-on form of the CoCbl complex, but is mainly due to electronic rearrangements when the reaction takes place on the base-off form of the complex. The latter behavior emerges from differences in the synchronicity of the bond strengthening/weakening processes along the reaction path; the base-on mode of CoCbl is able to decrease the synchronicity of the chemical events. This work gives new molecular-level insights into the role of Cbl-based systems in the cleavage of C-F bonds. These insights have potential implications for research into processes for degrading fluorine-containing pollutants. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
21. Macro- and micromechanical behaviors of poly(lactic acid)-hydroxyapatite electrospun composite scaffolds.
- Author
-
Sánchez-Arévalo, F., Muñoz-Ramírez, L., Álvarez-Camacho, M., Rivera-Torres, F., Maciel-Cerda, A., Montiel-Campos, R., and Vera-Graziano, R.
- Subjects
MICROELECTROMECHANICAL systems ,POLYLACTIC acid ,HYDROXYAPATITE ,COMPOSITE materials ,STRAINS & stresses (Mechanics) - Abstract
It was demonstrated that the macro- and micromechanical behaviors of electrospun composite scaffolds based on PLA and HA can be simultaneously studied using 3D digital image correlation strain measurements coupled with an axial tensile test. It was proven that the addition of a small quantity (2%) of HA particles into PLA electrospun scaffolds decreased their mechanical properties by approximately 40 and 60% at the micro- and macroscales, respectively; nevertheless, when this amount was increased beyond 2% of HA, the composites recovered their stiffness, showing Young's moduli ranging between 400 and 600 MPa. Hence, the mechanical responses of PLA-4% HA and PLA-6% HA electrospun scaffolds were conveniently enhanced with the addition of hydroxyapatite nanoparticles. The micromechanical measurements were able to capture the microstrain mechanism between electrospun nanofibers and the effect of HA nanoparticles on their mechanical response. This methodology could be a powerful tool for developing scaffolds for specific applications in tissue engineering. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
22. Mean residence time by hierarchical clustering analysis.
- Author
-
Guzzardi, L., Cazar, D. F., del Hierro, C. V., Torres, F. J., and Méndez, M. A.
- Subjects
MAGNETIC resonance imaging ,CLUSTER analysis (Statistics) ,HIERARCHICAL clustering (Cluster analysis) ,MOLECULAR dynamics ,DATA analysis - Abstract
A revised method, based on the hierarchical clustering data analysis technique, is proposed as an improved approach to estimate the mean residence time (MRT) related to the interaction between a molecule and its solvent as described via molecular dynamics simulations. Besides the description of the methodology, it is shown that our revised approach improves significantly the MRT evaluation of a representative model of a family of magnetic resonance imaging contrast agents when compared with the MRT value obtained for the same system by adopting a standard technique. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
23. Visual perception for the 3D recognition of geometric pieces in robotic manipulation.
- Author
-
Mateo, C., Gil, P., and Torres, F.
- Subjects
VISUAL perception ,GEOMETRIC analysis ,THREE-dimensional modeling ,POSE estimation (Computer vision) ,ROBOTICS - Abstract
During grasping and intelligent robotic manipulation tasks, the camera position relative to the scene changes dramatically because the robot is moving to adapt its path and correctly grasp objects. This is because the camera is mounted at the robot effector. For this reason, in this type of environment, a visual recognition system must be implemented to recognize and 'automatically and autonomously' obtain the positions of objects in the scene. Furthermore, in industrial environments, all objects that are manipulated by robots are made of the same material and cannot be differentiated by features such as texture or color. In this work, first, a study and analysis of 3D recognition descriptors has been completed for application in these environments. Second, a visual recognition system designed from specific distributed client-server architecture has been proposed to be applied in the recognition process of industrial objects without these appearance features. Our system has been implemented to overcome problems of recognition when the objects can only be recognized by geometric shape and the simplicity of shapes could create ambiguity. Finally, some real tests are performed and illustrated to verify the satisfactory performance of the proposed system. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
24. On the thermodynamic stability of the intermolecular association between Lewis acids and Lewis bases: a DFT study.
- Author
-
Becerra, Marcos, Real-Enriquez, Misael, Espinosa-Gavilanes, Carlos, Zambrano, Cesar H., Almeida, Rafael, Torres, F. Javier, and Rincón, Luis
- Subjects
LEWIS bases ,LEWIS acids ,LEWIS pairs (Chemistry) ,DISPERSION (Chemistry) ,POLAR effects (Chemistry) - Abstract
The intermolecular association of twelve combinations of six different Lewis acids and Lewis bases (i.e., R
3 A–BR′3 where A = B and Al; B = N and P; R = H, F, and C6 F5 ; R′ = H, CH3 , and C(CH3 )3 ) was theoretically described by means of DFT calculations using the dispersion-corrected ωB97x-D and B97D functionals in conjunction with the 6-311++G(2d,2p) basis set including toluene as solvent through the PCM-SMD implicit solvent scheme. All the studied Lewis pairs appeared to be stable on the basis of computed BSSE-corrected interaction energies; however, the free energies of formation computed in solution (ΔGsolv ) indicate that three Lewis acid–base combinations can be considered frustrated Lewis pairs (FLPs). Besides, the four features that characterize FLPs are: (1) large distances between the acid and base centers, (2) negligible changes in the geometry of the acid, (3) weak interaction energies, and (4) non-covalent dispersion energy contributing to almost the entire interaction energy. In the present work, we introduce two ad hoc indexes intended to quantify separately the electronic and steric factors, which have a direct effect in the intermolecular association of Lewis acids and Lewis bases and can be used to distinguished FLPs from classical Lewis adducts. Based on the aforementioned ad hoc indexes, the existence of a new kind of complexes that are "intermediate" between classical complexes and FLPs is proposed. [ABSTRACT FROM AUTHOR]- Published
- 2016
- Full Text
- View/download PDF
25. The Fate of Freedom of a Space Exploration Mission Encountering Life and the Liberty of the ˵Encountered″ Extra-Terrestrial Beings.
- Author
-
Martín-Torres, F. Javier and Zorzano, María-Paz
- Published
- 2015
- Full Text
- View/download PDF
26. Downscaling of Solar Irradiation from Satellite Estimates.
- Author
-
Antoñanzas-Torres, F., Antonanzas, J., Martínez-de-Pisón, F. J., Alia-Martinez, M., and Perpiñán-Lamigueiro, O.
- Published
- 2015
- Full Text
- View/download PDF
27. Use of Wireless Sensor Network to Control Landslides Interacting with Infrastructures.
- Author
-
Combarros Hernández, G., García Garijo, A., Antoñanzas-Torres, F., Alonso García, E., and Fernández Martínez, R.
- Published
- 2015
- Full Text
- View/download PDF
28. A Straightforward Implementation of a GPU-accelerated ELM in R with NVIDIA Graphic Cards.
- Author
-
Alia-Martinez, M., Antonanzas, J., Antonanzas-Torres, F., Pernía-Espinoza, A., and Urraca, R.
- Published
- 2015
- Full Text
- View/download PDF
29. Transient liquid water and water activity at Gale crater on Mars.
- Author
-
Martín-Torres, F. Javier, Zorzano, María-Paz, Valentín-Serrano, Patricia, Harri, Ari-Matti, Genzer, Maria, Kemppinen, Osku, Rivera-Valentin, Edgard G., Jun, Insoo, Wray, James, Bo Madsen, Morten, Goetz, Walter, Mcewen, Alfred S., Hardgrove, Craig, Renno, Nilton, Chevrier, Vincent F., Mischna, Michael, Navarro-González, Rafael, Martínez-Frías, Jesús, Conrad, Pamela, and Mcconnochie, Tim
- Subjects
- *
GALE Crater (Mars) , *WATER supply , *PERCHLORATES , *HUMIDITY , *ATMOSPHERIC temperature - Abstract
Water is a requirement for life as we know it. Indirect evidence of transient liquid water has been observed from orbiter on equatorial Mars, in contrast with expectations from large-scale climate models. The presence of perchlorate salts, which have been detected at Gale crater on equatorial Mars by the Curiosity rover, lowers the freezing temperature of water. Moreover, perchlorates can form stable hydrated compounds and liquid solutions by absorbing atmospheric water vapour through deliquescence. Here we analyse relative humidity, air temperature and ground temperature data from the Curiosity rover at Gale crater and find that the observations support the formation of night-time transient liquid brines in the uppermost 5 cm of the subsurface that then evaporate after sunrise. We also find that changes in the hydration state of salts within the uppermost 15 cm of the subsurface, as measured by Curiosity, are consistent with an active exchange of water at the atmosphere-soil interface. However, the water activity and temperature are probably too low to support terrestrial organisms. Perchlorates are widespread on the surface of Mars and we expect that liquid brines are abundant beyond equatorial regions where atmospheric humidity is higher and temperatures are lower. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
30. High Temperature Oxidation and Its Effects on Microstructural Changes of Hot-Rolled Low Carbon Non-oriented Electrical Steels During Air Annealing.
- Author
-
Gutiérrez-Castañeda, E., Salinas-Rodríguez, A., Deaquino-Lara, R., and Márquez-Torres, F.
- Subjects
OXIDATION ,MICROSTRUCTURE ,ELECTRICAL steel ,ANNEALING of metals ,PHASE transitions ,MATERIALS science - Abstract
This paper reports the influence of temperature on external oxidation and its effect on microstructural changes of hot-rolled non-oriented electrical steels during air-annealing treatments. Annealing during 150 min at temperatures above 700 °C, promotes the formation of two oxide layers: an inner iron-silicon-aluminum oxide and an outer three-layered wüstite-magnetite-hematite oxide. Thickness and oxide characteristics depend on temperature and influence other microstructural changes. Significant decarburization occurs at 800 and 850 °C when thin and cracked oxide structures are formed. At higher temperatures, decarburization becomes slower due to the increase of oxide thickness and a transition from cracked to crack-free structures, until at 950 and 1,050 °C, decarburization is practically inhibited. Absence of decarburization is confirmed by the increment of carbides volume fraction resulting from γ-Fe → α-Fe + FeC phase transformation. Finally, slow decarburization leads to normal grain growth, while intense decarburization favors abnormal growth with significant reduction in the amount of secondary particles. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
31. Event-Based Visual Servoing with Features' Prediction.
- Author
-
Garcia, G. J., Pomares, J., Torres, F., and Gil, P.
- Published
- 2014
- Full Text
- View/download PDF
32. FRISER-IRMIX Database: A Web-Based Support System with Implications in Planetary Mineralogical Studies, Ground Temperature Measurements and Astrobiology.
- Author
-
Martínez-Frias, Jesús, Rubio, María Serrano, Martín-Torres, F. Javier, Zorzano, María Paz, Rodríguez-Manfredi, José A., Gómez-Elvira, Javier, and team, REMS
- Published
- 2014
- Full Text
- View/download PDF
33. Cellulose Based Blends, Composites and Nanocomposites.
- Author
-
Torres, F. G., Troncoso, O. P., Torres, C., and Grande, C. J.
- Published
- 2013
- Full Text
- View/download PDF
34. A Mathematic Approach to Nitrogen Fixation Through Earth History.
- Author
-
Delgado-Bonal, Alfonso and Martín-Torres, F. Javier
- Published
- 2013
- Full Text
- View/download PDF
35. SNC Meteorites: Atmosphere Implantation Ages and the Climatic Evolution of Mars.
- Author
-
Moyano-Cambero, C. E., Trigo-Rodríguez, Josep M., and Martín-Torres, F. Javier
- Published
- 2013
- Full Text
- View/download PDF
36. Implication of Impacts in the Young Earth Sun Paradox and the Evolution of Earth's Atmosphere.
- Author
-
Trigo-Rodríguez, Josep M. and Martín-Torres, F. Javier
- Published
- 2013
- Full Text
- View/download PDF
37. Sparse Numerical Semigroups.
- Author
-
Munuera, C., Torres, F., and Villanueva, J.
- Abstract
We investigate the class of numerical semigroups verifying the property ρ
i + 1 − ρi ≥ 2 for every two consecutive elements smaller than the conductor. These semigroups generalize Arf semigroups. [ABSTRACT FROM AUTHOR]- Published
- 2009
- Full Text
- View/download PDF
38. SASEPA: Simultaneous Allocation and Scheduling with Exclusion and Precedence Relations Algorithm.
- Author
-
Fernández, C., Torres, F., and Puente, S. T.
- Abstract
An algorithm for allocating and scheduling tasks in multiprocessor environments is presented. Its main characteristic is its orientation towards machine vision applications. In this sense it deals with the peculiarities of systems which combine generic-type processors with Image Acquisition and Processing Boards. The main goal of the algorithm is total processing time reduction; such are the requirements when we deal with automated industrial inspection applications. By simultaneously tackling the phases of allocation and scheduling, the results obtained are better than those offered by traditional algorithms. The system is applied to a process of citrus fruit inspection, and its performances are also evaluated over randomly generated task graphs. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
39. Mathematical Morphology and Binary Geodesy for Robot Navigation Planning.
- Author
-
Singh, Sameer, Singh, Maneesha, Apte, Chid, Perner, Petra, Ortiz, F., Puente, S., and Torres, F.
- Abstract
A new method for obtaining the optimal path to robot navigation in 2-D environments is presented in this paper. To obtain the optimal path we use mathematical morphology in binary worlds and the geodesic distance. The navigation algorithm is based on the search for a path of minimum cost by using the wave-front of the geodesic distance of the mathematical morphology. The optimal path will be the one that minimize the direction changes of the robot. The algorithm of optimal path will be applied in several and complex 2-D environments. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
40. Simultaneous infection by four feline lungworm species and implications for the diagnosis.
- Author
-
Varcasia, A., Brianti, E., Tamponi, C., Pipia, A., Cabras, P., Mereu, M., Dantas-Torres, F., Scala, A., and Otranto, D.
- Subjects
LUNGWORMS ,PARASITIC diseases ,CAT diseases ,RIBOSOMAL DNA ,MITOCHONDRIAL DNA - Abstract
Besides Aelurostrongylus abstrusus, other parasites belonging to the superfamily Metastrongyloidea, namely Oslerus rostratus, Troglostrongylus brevior and to the family Trichuridae, i.e. Eucoleus aerophilus (syn. Capillaria aerophila), have also been reported as agents of respiratory infection in domestic cats. A case of simultaneous infection by four feline lungworm species in Sardinia is herein described. An adult female cat ( Felis silvestris catus), road-killed in the southeast part of Sardinia (municipality of Villacidro, province of Cagliari), Italy, was referred to the Laboratory of Parasitology of the Veterinary Teaching Hospital in Sassari. At necropsy, the lungs were examined and dissected under a stereomicroscope for the presence of parasites, and first-stage larvae (L1) of broncho-pulmonary nematodes were searched for in a faecal sample using the Baermann method. Parasites collected in the lungs were morphologically identified as A. abstrusus, E. aerophilus, and O. rostratus. In addition to the above species, L1s of Troglostrongylus spp. were detected at coproscopy but no adult specimen was found in the lungs. The morphological identification was confirmed by the molecular amplification and sequencing of cox1 mitochondrial gene, 18S and ITS2 ribosomal DNA. This finding stands as the first simultaneous infection by four feline lungworm species in the same animal, and as the first report of O. rostratus and E. aerophilus in Sardinia. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
41. Neuroprotective effects of guanosine administration on behavioral, brain activity, neurochemical and redox parameters in a rat model of chronic hepatic encephalopathy.
- Author
-
Paniz, L., Calcagnotto, M., Pandolfo, P., Machado, D., Santos, G., Hansel, G., Almeida, R., Bruch, R., Brum, L., Torres, F., Assis, A., Rico, E., and Souza, D.
- Subjects
LABORATORY rats ,HEPATIC encephalopathy ,GUANOSINE ,DRUG antagonism ,NEUROPROTECTIVE agents ,OXIDATIVE stress ,THERAPEUTICS ,ANIMAL behavior - Abstract
It is well known that glutamatergic excitotoxicity and oxidative stress are implicated in the pathogenesis of hepatic encephalopathy (HE). The nucleoside guanosine exerts neuroprotective effects through the antagonism against glutamate neurotoxicity and antioxidant properties. In this study, we evaluated the neuroprotective effect of guanosine in an animal model of chronic HE. Rats underwent bile duct ligation (BDL) and 2 weeks later they were treated with i.p. injection of guanosine 7.5 mg/kg once a day for 1-week. We evaluated the effects of guanosine in HE studying several aspects: a) animal behavior using open field and Y-maze tasks; b) brain rhythm changes in electroencephalogram (EEG) recordings; c) purines and glutamate levels in the cerebral spinal fluid (CSF); and d) oxidative stress parameters in the brain. BDL rats presented increased levels of glutamate, purines and metabolites in the CSF, as well as increased oxidative damage. Guanosine was able not only to prevent these effects but also to attenuate the behavioral and EEG impairment induced by BDL. Our study shows the neuroprotective effects of systemic administration of guanosine in a rat model of HE and highlights the involvement of purinergic system in the physiopathology of this disease. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
42. Cercopithifilaria spp. in dogs in Sardinia Island (Italy).
- Author
-
Solinas, C., Varcasia, A., Brianti, E., Giannetto, S., Pipia, A., Columbano, N., Tosciri, G., Dantas-Torres, F., Garippa, G., Otranto, D., and Scala, A.
- Subjects
DOGS ,HAPLOTYPES ,CYTOCHROME oxidase ,POLYMORPHISM (Zoology) ,BROWN dog tick - Abstract
A survey on Cercopithifilaria spp. was carried out on owned and kennelled dogs in Sardinia, Italy. A total of 180 dogs were sampled and tested by microscopic detection or PCR of dermal microfilariae in skin snip sediments. The overall prevalence for Cercopithifilaria spp. at both microscopy and molecular tests was 9.4 % (17/180), while 8.3 % (15/180) of dogs scored positive at microscopic detection of sediments only. Of the 225 microfilariae measured, 212 were identified as Cercopithifilaria bainae and the remaining as Cercopithifilaria sp. II. All samples were molecularly processed for specific amplification of cytochrome oxidase subunit 1 ( cox1) and ribosomal 12S gene fragments. The Basic Local Alignment Search Tool analysis of the cox1 and 12S sequences here obtained showed a high nucleotide similarity (99 and 100 %, respectively) with those of C. bainae available in GenBank. In particular, cox1 haplotype I (HI; n= 14), haplotype HXVIII ( n= 2), and a new haplotype, named HXIX ( n= 1), differing for a single polymorphism from HI, were detected. This study reports data on the occurrence, distribution, and genetic makeup of C. bainae and Cercopithifilaria sp. II infesting dogs in Sardinia, suggesting that these filarioids are spread in areas where Rhipicephalus sanguineus sensu lato ticks occur. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
43. Quasi-Dirac neutrinos and solar neutrino data.
- Author
-
Rossi-Torres, F., Machado, A. C. B., and Pleitez, V.
- Subjects
- *
SOLAR neutrinos , *DIRAC function , *DATA analysis , *LEPTONS (Nuclear physics) , *NEUTRINO oscillation , *PARAMETER estimation , *RADIATIVE corrections - Abstract
We will present an analysis of the solar neutrino data in the context of a 3+1 quasi-Dirac neutrino model in which the lepton mixing matrix is given at tree level by the tribimaximal matrix. When radiative corrections are taken into account, new effects in neutrino oscillations, as νe→ νs, could appear. This oscillation is constrained by the solar neutrino data. In our analysis, we have found an allowed region for our two free parameters ϵ and m1. The radiative correction, ϵ, can vary approximately from 5×10 −9 to 10 −6 and the calculated fourth mass eigenstate, m4, varies in the interval 0.01–0.2 eV, at 2 σ level. These results are in agreement with the ones presented in the literature in 2+1 and 2+2 quasi-Dirac models. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
44. Generalized Hermitian codes.
- Author
-
Munuera, C., Sepúlveda, A., and Torres, F.
- Subjects
GENERALIZATION ,HERMITIAN forms ,CODING theory ,ALGEBRAIC geometry ,CURVES ,PARAMETER estimation ,MATHEMATICAL analysis ,APPLIED mathematics - Abstract
We investigate one-point algebraic geometry codes defined from curves related to the Hermitian curve. We obtain codes attaining new records on the parameters. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
45. Comparison of Gene Expression Profiles Between Pansensitive and Multidrug-Resistant Strains of Mycobacterium tuberculosis.
- Author
-
Peñuelas-Urquides, K., González-Escalante, L., Villarreal-Treviño, L., Silva-Ramírez, B., Gutiérrez-Fuentes, D., Mojica-Espinosa, R., Rangel-Escareño, C., Uribe-Figueroa, L., Molina-Salinas, G., Dávila-Velderrain, J., Castorena-Torres, F., Bermúdez de León, M., and Said-Fernández, S.
- Subjects
GENE expression ,MULTIDRUG-resistant tuberculosis ,MYCOBACTERIUM tuberculosis ,POLYMERASE chain reaction ,PROTEIN microarrays - Abstract
Mycobacterium tuberculosis has developed resistance to anti-tuberculosis first-line drugs. Multidrug-resistant strains complicate the control of tuberculosis and have converted it into a worldwide public health problem. Mutational studies of target genes have tried to envisage the resistance in clinical isolates; however, detection of these mutations in some cases is not sufficient to identify drug resistance, suggesting that other mechanisms are involved. Therefore, the identification of new markers of susceptibility or resistance to first-line drugs could contribute (1) to specifically diagnose the type of M. tuberculosis strain and prescribe an appropriate therapy, and (2) to elucidate the mechanisms of resistance in multidrug-resistant strains. In order to identify specific genes related to resistance in M. tuberculosis, we compared the gene expression profiles between the pansensitive H37Rv strain and a clinical CIBIN:UMF:15:99 multidrug-resistant isolate using microarray analysis. Quantitative real-time PCR confirmed that in the clinical multidrug-resistant isolate, the esxG, esxH, rpsA, esxI, and rpmI genes were upregulated, while the lipF, groES, and narG genes were downregulated. The modified genes could be involved in the mechanisms of resistance to first-line drugs in M. tuberculosis and could contribute to increased efficiency in molecular diagnosis approaches of infections with drug-resistant strains. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
46. EXISTENCE OF POSITIVE SOLUTIONS FOR A BOUNDARY VALUE PROBLEM OF A NONLINEAR FRACTIONAL DIFFERENTIAL EQUATION.
- Author
-
TORRES, F. J.
- Subjects
- *
BOUNDARY value problems , *DIFFERENTIAL equations , *MATHEMATICS theorems , *INDEX theory (Mathematics) , *CALCULUS - Abstract
This paper presents conditions for the existence and multiplicity of positive solutions for a boundary value problem of a nonlinear fractional differential equation. We show that it has at least one or two positive solutions. The main tool is Krasnosel'skii fixed point theorem on cone and fixed point index theory. [ABSTRACT FROM AUTHOR]
- Published
- 2013
47. The rs5743836 polymorphism in TLR9 confers a population-based increased risk of non-Hodgkin lymphoma.
- Author
-
Carvalho, A, Cunha, C, Almeida, A J, Osório, N S, Saraiva, M, Teixeira-Coelho, M, Pedreiro, S, Torrado, E, Domingues, N, Gomes-Alves, A G, Marques, A, Lacerda, J F, da Silva, M G, Gomes, M, Pinto, A C, Torres, F, Rendeiro, P, Tavares, P, Di Ianni, M, and Medeiros, R
- Subjects
HODGKIN'S disease treatment ,GENETIC polymorphisms ,IMMUNODEFICIENCY ,INFLAMMATION ,IMMUNITY ,TOLL-like receptors ,GENETIC transcription - Abstract
Non-Hodgkin lymphoma (NHL) has been associated with immunological defects, chronic inflammatory and autoimmune conditions. Given the link between immune dysfunction and NHL, genetic variants in toll-like receptors (TLRs) have been regarded as potential predictive factors of susceptibility to NHL. Adequate anti-tumoral responses are known to depend on TLR9 function, such that the use of its synthetic ligand is being targeted as a therapeutic strategy. We investigated the association between the functional rs5743836 polymorphism in the TLR9 promoter and risk for B-cell NHL and its major subtypes in three independent case-control association studies from Portugal (1160 controls, 797 patients), Italy (468 controls, 494 patients) and the US (972 controls, 868 patients). We found that the rs5743836 polymorphism was significantly overtransmitted in both Portuguese (odds ratio (OR), 1.85; P=7.3E−9) and Italian (OR, 1.84; P=6.0E−5) and not in the US cohort of NHL patients. Moreover, the increased transcriptional activity of TLR9 in mononuclear cells from patients harboring rs5743836 further supports a functional effect of this polymorphism on NHL susceptibility in a population-dependent manner. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
48. Improvement of Electrochemical Surface Properties in Steel Substrates Using a Nanostructured CrN/AlN Multilayer Coating.
- Author
-
Cabrera, G., Torres, F., Caicedo, J., Aperador, W., Amaya, C., and Prieto, P.
- Subjects
ELECTROCHEMISTRY ,SURFACES (Technology) ,STEEL ,SUBSTRATES (Materials science) ,NANOSTRUCTURES ,CHROMIUM ,ALUMINUM nitride ,CORROSION & anti-corrosives - Abstract
Improvement of corrosion properties on AISI D3 steel surfaces coated with [CrN/AlN] multilayered system deposited for various periods (Λ) via magnetron sputtering has been studied in this work exhaustively. For practical effects compared were the latter properties with CrN and AlN single layers deposited with the same conditions as the multilayered systems. The coatings were characterized in terms of crystal phase; chemical composition, micro-structural, and electrochemical properties by x-ray diffractometry, energy dispersive x-ray, Fourier transforming infrared spectroscopy, atomic force microscopy, scanning electron microscopy, Tafel polarization curves, and electrochemical impedance spectroscopy. Corrosion evolution was observed via optical microscopy. Results from x-ray diffractometry analysis revealed that the crystal structure of [CrN/AlN] multilayered coatings has an NaCl-type lattice structure and hexagonal structure (wurtzite-type) for CrN and AlN, respectively, i.e., it was made non-isostructural multilayered. The best behavior was obtained by the multilayered period: Λ = 60 nm (50 bilayers), showing the maximum corrosion resistance (polarization resistance of 1.18 KΩ, and corrosion rate of 1.02 mpy). Those results indicated an improvement of anticorrosive properties, compared to the CrN/AlN multilayer system with 1 bilayer at 98 and 80%, respectively. Furthermore, the corrosion resistance of steel AISI D3 is improved beyond 90%. These improvement effects in multilayered coatings could be attributed to the number of interfaces that act as obstacles for the inward and outward diffusions of ion species, generating an increment in the energy or potential required for translating the corrosive ions across the coating/substrate interface. Moreover, the interface systems affect the means free path on the ions toward the metallic substrate, due to the decreasing of the defects presented in the multilayered coatings. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
49. The intOA Experiment: A Study of Ocean-Atmosphere Interactions Under Moderate to Strong Offshore Winds and Opposing Swell Conditions in the Gulf of Tehuantepec, Mexico.
- Author
-
Ocampo-Torres, F., García-Nava, H., Durazo, R., Osuna, P., Díaz Méndez, G., and Graber, H.
- Subjects
- *
OCEAN-atmosphere interaction , *SURFACE waves (Fluids) , *SEASHORE , *MOMENTUM transfer , *REMOTE sensing , *MATHEMATICAL models , *OCEAN surface topography - Abstract
The Gulf of Tehuantepec air-sea interaction experiment ( intOA) took place from February to April 2005, under the Programme for the Study of the Gulf of Tehuantepec (PEGoT, Spanish acronym for Programa para el Estudio del Golfo de Tehuantepec). PEGoT is underway aiming for better knowledge of the effect of strong and persistent offshore winds on coastal waters and their natural resources, as well as performing advanced numerical modelling of the wave and surface current fields. One of the goals of the intOA experiment is to improve our knowledge on air-sea interaction processes with particular emphasis on the effect of surface waves on the momentum flux for the characteristic and unique conditions that occur when strong Tehuano winds blow offshore against the Pacific Ocean long period swell. For the field campaign, an air-sea interaction spar (ASIS) buoy was deployed in the Gulf of Tehuantepec to measure surface waves and the momentum flux between the ocean and the atmosphere. High frequency radar systems (phase array type) were in operation from two coastal sites and three acoustic Doppler current profilers were deployed near-shore. Synthetic aperture radar images were also acquired as part of the remote sensing component of the experiment. The present paper provides the main results on the wave and wind fields, addressing the direct calculation of the momentum flux and the drag coefficient, and gives an overview of the intOA experiment. Although the effect of swell has been described in recent studies, this is the first time for the very specific conditions encountered, such as swell persistently opposing offshore winds and locally generated waves, to show a clear evidence of the influence on the wind stress of the significant steepness of swell waves. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
50. Disassembly planning strategies for automatic material removal.
- Author
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Puente, S. T., Torres, F., Reinoso, O., and Paya, L.
- Subjects
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DISASSEMBLERS (Computer programs) , *ALGORITHMS , *MATERIALS , *TOYS , *PLANNING , *AMUSEMENTS - Abstract
Nowadays, the material disassembly is an important issue for the industry. This paper presents an algorithm to sequence the task to be performed in the disassembly of a specific material from a product or to separate all the materials of a product. It uses a hierarchical model of the product that was used previously in the computation of the sequence to disassemble a component, although it tries to separate the materials, keeping the damage to the components as minimum as possible. The algorithm is tested with the disassembly of toys. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
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