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Nongauge bright soliton of the nonlinear Schrödinger (NLS) equation and a family of generalized NLS equations
Get PDF"We present an approach to the bright soliton solution of the nonlinear Schrödinger (NLS) equation from the standpoint of introducing a constant potential term in the equation. We discuss a "nongauge" bright soliton for which both the envelope and the phase depend only on the traveling variable. We also construct a family of generalized NLS equations with solitonic sechp solutions in the traveling variable and find an exact equivalence with other nonlinear equations, such as the Korteveg-de Vries (KdV) and Benjamin-Bona-Mahony (BBM) equations when p = 2.
Simple approach for ranking structure determining residues
Get PDF"Mutating residues has been a common task in order to study structural properties of the protein of interest. Here, we propose and validate a simple method that allows the identification of structural determinants; i.e., residues essential for preservation of the stability of global structure, regardless of the protein topology. This method evaluates all of the residues in a 3D structure of a given globular protein by ranking them according to their connectivity and movement restrictions without topology constraints. Our results matched up with sequence-based predictors that look up for intrinsically disordered segments, suggesting that protein disorder can also be described with the proposed methodology.
Great kiskadee (Pitangus sulphuratus ) in the Mexican Highland Plateau
Get PDF"The Great kiskadee (Pitangus sulphuratus) has a continuous distribution in both slopes of Mexico, mainly in tropical zones. As a result of monthly samplings from December 2006 to August 2013, we report the occurrence of this species in eastern Aguascalientes and the Highland Plateau region of San Luis Potosi. Based on these records, we suggest that this species can be considered as a resident for this region, thus suggesting that its geographic distribution could be extended to the central plateau of Mexico.
Role of the intrinsic properties of partially reduced graphene oxides on the chemical transformation of iopromide
Get PDF"The role of the intrinsic properties of graphene oxide (GO) and partially reduced graphene oxide (rGO), and their use as redox mediator (RM) is reported, for the first time, on the chemical transformation of iopromide (IOP), an iodinated X-ray contrast medium, under anaerobic conditions. The structural and physicochemical properties of GO containing different types of oxygenated groups, were analyzed by Boehm titrations, point of zero charge (pHPZC), pKa's distribution, scanning electron microscopy (SEM), electrochemical analysis, as well as by Raman, Fourier transform infrared and UV–Vis spectroscopy. Complete characterization of GO-based materials revealed the removal of different oxygenated groups, such as epoxy and hydroxyl groups, and a transition from an amorphous to a more crystalline structure on partially reduced GO. Moreover, when rGO materials were tested as RM, they promoted a faster and greater extent of IOP transformation up to 5.2-fold with sulfide as electron donor. Results showed a correlation between the reduction degree of GO and its ability to act as RM, which was reflected in the dehalogenation and transformation degree of IOP. Additionally, the chemical transformation pathway of IOP is proposed based on HPLC-MS analysis.
Producción de péptidos contra influenza A H1N1 en Chlamydomonas reinhardtii
Get PDF"La infección por el virus de la influenza es la mayor causa de las enfermedades
respiratorias en el mundo. El virus tiene mecanismos para la evasión del sistema
inmune y para crear nuevas cepas pandémicas, por tal razón, las vacunas deben
actualizarse anualmente. El objetivo del este trabajo fue expresar un péptido
antigénico basado en epítopos conservados del virus de la influenza A H1N1 y del
péptido antiviral bloqueador de entrada (EB), en la microalga Chlamydomonas
reinhardtii, ya que es un sistema rápido y económico para producción de proteínas
recombinantes. Los genes del péptido antigénico y del péptido antiviral EB se
diseñaron con base en ensayos in silico y se optimizaron para su expresión en la
microalga tanto para la transformación nuclear como en el cloroplasto. Las
construcciones para expresión nuclear se clonaron en el vector pChlamy_1 y se
transformaron vía Agrobacterium tumefaciens. Para la transformación de los
cloroplastos por biobalística se usó el vector p463. Las líneas transgénicas
nucleares y transplastómicas para el gen EB fueron confirmadas por PCR, al igual
que para el gen de resistencia APH7 y para corroborar la homoplastia. El dot blot
indicó que el péptido EB en la línea transplastómica se acumula en la fracción
insoluble, sin embargo, no se pudo detectar el péptido EB por dot blot en las líneas
transgénicas. La cuantificación de la proteína realizada por ELISA mostró que las
líneas transgénicas nucleares producen de 0.3 a 1.8 ?g de del péptido EB por
cada gramo de biomasa húmeda; mientras que, para la líneas transplastómicas,
se obtiene de 0.09 a 18 ?g del péptido EB por gramo de biomasa húmeda. La
transformación nuclear de la construcción PA-pChlamy_1 permitió la obtención de
170 clonas resistentes a higromicina, mientras que la transformación del
cloroplasto permitió la obtención de 500 clonas resistentes a espectinomicina.
Estamos por realizar el análisis de efectividad biológica del péptido EB en líneas
celulares y la efectividad de las proteínas antigénicas en ratones para detectar la
producción de anticuerpos y demostrar su funcionalidad. Los resultados
preliminares indican que es posible utilizar a C. reinhardtii como plataforma para la
producción de péptidos que posiblemente que ayuden a combatir al virus de la
influenza.""Influenza infections are the major cause of respiratory diseases in the world. The
viruses have evasion mechanisms of the immune system, so new pandemic
strains can arise. For this reason, the influenza vaccines need to be redesigned
annually. The aim of the current work was to express an antigenic peptide based
on the conserved epitopes from influenza virus A H1N1 and the antiviral peptide
entry blocker (EB) in Chlamydomonas reinhardtii, which is a fast and economic
system for recombinant protein production. Antigenic peptide genes and antiviral
peptide, were designed with in silico assays and were optimized for algae
expression both for nuclear and chloroplast transformation. Constructs for nuclear
expression were cloned in the pChlamy_1 vector and were transformed via
Agrobacterium tumefaciens. For chloroplast transformation, via biolistic, p463
vector was used. Nuclear transgenic and transplastomic lines from EB gene were
confirmed by PCR, they were also tested for the presence of resistance gene and
for homoplasty. Dot blot indicated that EB peptide in the transplastomic lines was
accumulated in the insoluble fraction, however was not detected by dot blot in the
transgenic line. ELISA protein quantitation showed that nuclear transgenic lines
produced between 0.3 to 1.8 ?g per gram of wet biomass. While for transplastomic
lines, 0.09 to 18 ?g EB peptide per gram of wet biomass was obteined. We
obtained 170 hygromycin resistant clones for PA-pChlamy_1 nuclear
transformation and 500 spectinomycin resistant clones for chloroplast
transformation. We will perform biological assays to test the activity of EB peptide
in cellular lines and also the biological assay of antigenic proteins in mice to
demonstrate if they have biological activity. Preliminary results showed that is
possible to use C. reinhardtii as a platform to produce recombinant peptides that
perhaps can fight the influenza virus.
Influencia de la estructura vegetal, del paisaje y disponibilidad de presas sobre la ocupación de hábitat del cernícalo americano (Falco sparverius) en el Altiplano Potosino Zacatecano
Get PDF"El cernícalo americano es un ave rapaz con una amplia distribución en el
continente Americano. Las poblaciones del norte del continente han disminuido su
abundancia en los últimos años y se ha considerado que la causa de estas
disminuciones pudiera encontrarse parcialmente en sus rutas migratorias y zonas
de invernación, como son los semi-desiertos de México, donde a la vez existen
poblaciones residentes. La información sobre la ecología de esta especie en la zona
es escasa. Por lo que en este estudio se evaluó el efecto de la agricultura, estructura
vegetal y disponibilidad de presas sobre los patrones de ocupación de hábitat del
cernícalo americano en una zona semiárida del Altiplano Potosino-Zacatecano
durante primavera-verano del 2015 y otoño-invierno del 2015-2016. La probabilidad
de ocupación en primavera-verano fue de 0.47 y en otoño-invierno aumentó a 0.72
debido a la llegada de las poblaciones migratorias. El cernícalo mostró cierta
capacidad de adaptarse a la agricultura, sin embargo, en paisajes con proporciones
elevadas de agricultura disminuyó la ocupación. La presencia de perchas (yucas,
postes, quiotes de maguey) y la baja densidad vegetal determinaron un hábitat
favorable para el cernícalo. Los insectos fueron las presas más importantes durante
primavera-verano, mientras que durante otoño-invierno lo fueron los roedores. Hace
falta estudiar más a fondo como los agro-sistemas influyen en sus poblaciones y
determinar posibles diferencias en los requerimientos de hábitat de las poblaciones
residentes y migratorias.""The American kestrel is a widely distributed bird of prey within the Americas.
Abundance of it’s northern populations have significant declined in recent years. It
has proposed that some causes of these declines may take place in migratory routes
and wintering grounds, such as semi-deserts in Mexico, where resident populations
are present too. This project aims at assessing potential effects of agriculture, plant
structure, and prey availability on habitat occupancy patterns by the American kestrel
the Mexican semiarid highland plateau during two climatic seasons (spring-summer
2015 and autumn-winter 2015-2016). Occupancy probability was 0.47 during the
spring-summer period and increase to 0.72 in fall-winter due to the arrival of
migrants. Though the kestrel showed the ability to adapt to agriculture, landscapes
with high proportions of agriculture were unoccupied. As for the vegetation structure,
the presence of perches (yucas, posts, quiotes of maguey), as well as moderate
vegetation density determined a favorable habitat for kestrel occupancy. Whereas
insects were the most important prey during spring-summer, in autumn-winter
rodents were the main prey. Additional study is needed to evaluate effects of
agriculture in kestrel populations, as well as potential differences in habitat
requirements between resident and migratory populations.
Electrum, the gold–silver alloy, from the bulk scale to the nanoscale: synthesis, properties, and segregation rules
Get PDF"The alloy Au–Ag system is an important noble bimetallic phase, both historically (as “Electrum”) and now especially in nanotechnology, as it is applied in catalysis and nanomedicine. To comprehend the structural characteristics and the thermodynamic stability of this alloy, a knowledge of its phase diagram is required that considers explicitly its size and shape (morphology) dependence. However, as the experimental determination remains quite challenging at the nanoscale, theoretical guidance can provide significant advantages. Using a regular solution model within a nanothermodynamic approach to evaluate the size effect on all the parameters (melting temperature, melting enthalpy, and interaction parameters in both phases), the nanophase diagram is predicted. Besides an overall shift downward, there is a “tilting” effect on the solidus–liquidus curves for some particular shapes exposing the (100) and (110) facets (cube, rhombic dodecahedron, and cuboctahedron). The segregation calculation reveals the preferential presence of silver at the surface for all the polyhedral shapes considered, in excellent agreement with the latest transmission electron microscopy observations and energy dispersive spectroscopy analysis. By reviewing the nature of the surface segregated element of different bimetallic nanoalloys, two surface segregation rules, based on the melting temperatures and surface energies, are deduced. Finally, the optical properties of Au–Ag nanoparticles, calculated within the discrete dipole approximation, show the control that can be achieved in the tuning of the local surface plasmon resonance, depending of the alloy content, the chemical ordering, the morphology, the size of the nanoparticle, and the nature of the surrounding environment.
Indole modifies the central carbon flux in the anaerobic metabolism of Escherichia coli: application to the production of hydrogen and other metabolites
Get PDF"Indole is a bicyclic signaling molecule with effects on both eukaryotic and prokaryotic cells. The majority of studies of indole action have been performed with bacteria cultured under aerobic conditions and little information is available about its effects under anaerobic conditions. Here the effect of the indole on anaerobic metabolism of Escherichia coli WDHL was studied. Indole in the range 0.5–8 mM was added to the culture medium and cell growth, hydrogen and metabolite production were compared to cultures lacking indole. Results showed that while 8 mM indole abolished growth completely, 4 mM indole had a partial bacteriostatic effect and the maximum optical density of the culture decreased by 44% compared to the control cultures. In addition, 4 mM indole had an important effect on anaerobic metabolism. Hydrogen production increased from 650 ± 115 to 1137 ± 343 mL H2/L, and hydrogen yield increased from 0.45 ± 0.1 to 0.94 ± 0.34 mol H2/mol glucose, compared to the control culture. Carbon flux was also affected and the composition of the final by-products changed. Lactate (41 mM) was the main metabolite in the control cultures, whereas ethanol (56.2 mM) and acetate (41.2 mM) were the main metabolites in the cultures with 2 mM indole. We conclude that the supplementation of E. coli cultures with exogenous indole is a simple and novel strategy to improve the production of hydrogen as well as other metabolites such as ethanol used as biofuels.
Sand waves generation: a numerical investigation of the Infiernillo Channel in the Gulf of California
Get PDF"The effect of the coastal geometry on sand bed forms generation has been investigated for a tidal dominated area. Different hypothetical geometries of coastal channels with flat bottoms and unlimited sediment availability were exposed to strong oscillatory tidal currents to simulate the interaction of hydrodynamics and the bedload sediment transport. The hypothetical geometries stand for the idealization of the principal geographic features of the Infiernillo Channel, a coastal area of the Gulf of California where sandbanks and sand waves have been observed. A depth integrated hydrodynamic-numerical model and a parameterized formula to estimate the bedload sediment transport were applied coupled with a sediment conservation equation to determine the sea bottom morphodynamics. Model predictions in the Infiernillo Channel were compared to available satellite imagery. This investigation demonstrates that a vertical integrated numerical model is able to reproduce the development of incipient sand waves that exist in the Infiernillo Channel. Incipient sandbanks and shoals were also simulated. Sand waves with wavelengths of about 200 m were calculated on the same locations where sand waves actually exist. A crucial finding of this research was to show that the geometry of a shallow water basin and the presence of tidal velocity gradients associated with abrupt changes in the coastline alignment were critical in determining the sand-bed pattern generation. We demonstrate that a vertical variation of tidal currents is not necessary to generate sand waves.
Water splitting behavior of copper-cerium oxide nanorods and nanocubes using hydrazine as a scavenging agent
Get PDF"A one-step microwave synthesis using neither a template surfactant nor strong molar NaOH concentrations is reported. Well shaped nanorod and nanocube CeO2 structures were achieved in 0.5 and 4 h at a maximum irradiation of 200 W, respectively. Both nanostructures grew through different processes, they are dependent on the irradiation conditions, time and temperature. The photocatalytic water splitting evaluation of cerium oxide nanostructures was carried out using water contaminated with hydrazine and the surface “in-situ” functionalization of Cu0 nanoparticles (CuNPs) on the surface, achieving 753 μmol/h g of hydrogen generation. During the photocatalytic process, the “in-situ” reduction reaction (CuO → Cu0) occurring on the CeO2 surface promotes the electron transfer process due to the copper work function.