Análisis de riesgo potencial de Huanglongbing a través de tecnología geoespacial en Colombia

Huanglongbing (HLB) is the most destructive disease that currently impacts citrus in the world. HLB was first detected in the Americas in Brazil and then in Florida (the United States). The citrus growing areas of Colombia were free of the disease, but in April 2016, Instituto Colombiano Agropecuario (ICA) declared phytosanitary quarantine in the department of La Guajira due to the presence of HLB. At that time, the control and eradication actions were intensified; nonetheless, the report of the first half of 2018 prepared by ICA reported the presence of the HLB in six departments in northern Colombia. This study proposes a methodology to analyze the potential risk of HLB and its vector Diaphorina citri, through the use of geospatial technology, considering the location of plant hosts, the development time of the insect host in degree-days and bioclimatic variables. The results indicate that about 15 % of the citrus areas are at high risk of the presence of HLB. This method is presented as an option for monitoring the disease on a regional scale, which is also characterized by being automated, with high spatio-temporal dynamics, and can be used for early detection of the disease.Huanglongbing (HLB) es una de las enfermedades más destructivas que afecta a los cítricos en el mundo. En el continente americano, HLB se detectó primero en Brasil y posteriormente en Florida (Estados Unidos). Las áreas citrícolas de Colombia se mantuvieron libres de la enfermedad hasta que en abril de 2016 el Instituto Colombiano Agropecuario (ICA) declaró en cuarentena fitosanitaria al departamento de La Guajira por la presencia de HLB. En ese momento se intensificaron las acciones de control y erradicación; sin embargo, el informe del primer semestre de 2018 elaborado por el ICA reportó la presencia de HLB en seis departamentos del norte de Colombia. El presente estudio propone una metodología para analizar el riesgo potencial de HLB y su insecto vector Diaphorina citri mediante el uso de tecnología geoespacial, que permite determinar la ubicación de plantas hospederas, grados días de desarrollo del vector y variables bioclimáticas. Los resultados señalan que cerca del 15 % de las áreas citrícolas de Colombia se encuentra en un alto riesgo a la presencia de la enfermedad. Esta metodología se presenta como una opción para el monitoreo de la enfermedad a escala regional, ya que es automatizable y tiene una dinámica espacio-temporal alta que puede ser utilizada para la detección temprana de HLB

Synthesis and Characterization of Zn-Ni x

Mechanical ball milling assisted by sintering in the solid state was used in this research to produce the Zn-Nix system alloy. The derivative powder compositions of Zn-Nix (x = 0, 5, 10, 15, and 20 wt.%) were obtained to study the Ni effects on the microstructural and mechanical properties. It is worth remarking that conventional methods are not appropriate for the manufacture of the Zn-Nix system alloy. The morphological structure and phases were examined by optical microscopy, X-ray diffraction, and SEM/EDS elemental mapping, whereas the mechanical behavior was accomplished by means of a diamond indentation print (Hardness Vickers). The results showed that the intermetallic γ-ZnNi phase did not form during milling time (<4 h); it appears after the sintering process, which is associated with atomic diffusion mechanism through grain boundary at the minimum interfacial energy (ΔG256°C = −13.83 kJ·mol−1). The powder Zn-Ni10 was found to have better properties. Semispherical coarser particles were seen into the metal matrix (Zn δ-hcp structure) as segregates; however, each particle contains an intermetallic compound Zn-Ni that encloses the Ni (α-fcc structure) pure phase. The Ni-α phase was then transformed into a γ-ZnNi intermetallic compound which shifts to higher values of mechanical hardness from about 60 HV to 400 HV units

Síntesis de un nanocatalizador de carburo metálico Ni W Mo y el estudio de su efecto en la acuatermólisis para la recuperación mejorada del petróleo

Tesis (Doctorado en Ciencias en Metalurgia y Materiales), Instituto Politécnico Nacional, SEPI, ESIQIE, 2014, 1 archivo PDF, (143 páginas). tesis.ipn.m

Intercalated Intermetallic Compounds AlTi3 and Fe2Ti in Microrods and Microtubes Obtained by Invariant Reaction of Mechanically Milled System Al43Ti36Fe21

This paper reports the production of intermetallic microrods and microtubes from the decomposition of an intermetallic compound in an AlTiFe system. The intermetallic compound was obtained by mechanosynthesis of elemental powders of Al, Ti and Fe over 300 h at 400 rpm, sintering from compacted powder particles at 300 MPa per minute and at 900 &deg;C for 3600 s in an argon atmosphere. The milled and sintered samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The intermetallic AlTi3 and Fe3Al phases were obtained during the milling process. After sintering, a decomposition of these intermetallic phases was found&mdash;Al3Ti0.75Fe0.25, Al3Ti, FeTi, AlTi3, Ti9Al23, Fe2Ti, Al86Fe14 and Al0.4Fe0.6. As a result of the decomposition, we observed the formation of hexagonal rods with intercalated phases of AlTi3 and Fe2Ti

Synthesis and Characterization of Mechanically Alloyed, Nanostructured Cubic MoW Carbide

Carbides are used extensively as cutting tools, forming dies, and recently in catalysis applications, among other industrial applications. In this work, the synthesis and characterization of a nanostructured MoW bimetallic carbide were carried out by mechanical alloying with a mixture of elemental powders with a nominal composition of W1.5Mo6C2.5 at different grinding times as follows: 25, 50, and 75 h in a low-energy ball mill at a speed of 500 rpm and 125 and 150 h in a high-energy ball mill at a speed of 1500 rpm. The formation of a solid solution was observed at 150 h of milling; the nanostructured bcc MoW carbide corresponded to the main phase in the sample, besides the presence of the nanostructured MoW alloy as a secondary phase with an average crystal size of 40.8 nm. The phases and morphology at every stage of milling were studied by: X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Vickers hardness. As the milling time increased, the hardness of these particles increased from 10.5 to 31.48 GPa for the powder particles milled for 150 h. The samples obtained at 125 and 150 h of milling were evaluated during catalytic aqua-thermolysis of heavy oil to analyze fuel desulfurization properties by Fourier transform infrared (FTIR) techniques. The results showed the breaking of S-S bonds, indicating the existence of a desulfurization reaction of heavy oil

Sonochemical Synthesis of Nanostructured Ni-Fe-C System and Its Catalytic Activity Based on Decolorization of Reactive Black 5 Dye

This study investigates the thermal decomposition of acetyl acetonates of Ni(II) and Fe(III) via a sonochemical process at 20 kHz for 50 min. In the absence of magnetic fields the reactions of Ni(II) and Fe(III) acetyl acetonates under ultrasonic treatment produce Ni(OH)2 and FeO(OH) nanoparticles coated with carbon. The synthesized materials with different Ni-Fe stoichiometries, Ni90-Fe10, Ni80-Fe20, and Ni50-Fe50 wt%, were subjected to catalytic activity for dye decolorization of Reactive Black 5 (RB5, 100 mg/L) at room temperature using visible radiation. The correlation between the structural and optoelectronic properties and the catalytic performance of the Ni-Fe system with different stoichiometries is reported

Atomic-Scale Investigation on the Evolution of Tio2-Anatase Prepared by a Sonochemical Route and Treated with NaOH

To date, the formation mechanisms of TiO2, as well as its heterostructures, have not been clarified. Moreover, detailed research on the transition from a tetragonal anatase phase to the monoclinic phase of the TiO2(B) phase and their interface structure has been quite limited until now. In the present study, we report on the sonochemical synthesis of TiO2-anatase with a crystallite size of 5.2 &plusmn; 1.5 nm under different NaOH concentrations via the hydrothermal method. The use of alkaline solution and the effect of the temperature and reaction time on the formation and structural properties of TiO2-anatase nanopowders were studied. The effects of NaOH concentration on the formation and transformation of titanate structures are subject to thermal effects that stem from the redistribution of energy in the system. These mechanisms could be attributed to three phenomena: (1) the self-assembly of nanofibers and nanosheets, (2) the Ostwald ripening process, and (3) the self-development of hollow TiO2 mesostructures