ALMA 690 GHz observations of IRAS 16293-2422B: Infall in a highly optically-thick disk

We present sensitive, high angular resolution ($\sim$ 0.2 arcsec) submillimeter continuum and line observations of IRAS 16293-2422B made with the Atacama Large Millimeter/Submillimeter Array (ALMA). The 0.45 mm continuum observations reveal a single and very compact source associated with IRAS 16293-2422B. This submillimeter source has a deconvolved angular size of about 400 {\it milli-arcseconds} (50 AU), and does not show any inner structure inside of this diameter. The H$^{13}$CN, HC$^{15}$N, and CH$_{3}$OH line emission regions are about twice as large as the continuum emission and reveal a pronounced inner depression or "hole" with a size comparable to that estimated for the submillimeter continuum. We suggest that the presence of this inner depression and the fact that we do not see inner structure (or a flat structure) in the continuum is produced by very optically thick dust located in the innermost parts of IRAS 16293-2422B. All three lines also show pronounced inverse P-Cygni profiles with infall and dispersion velocities larger than those recently reported from observations at lower frequencies, suggesting that we are detecting faster, and more turbulent gas located closer to the central object. Finally, we report a small east-west velocity gradient in IRAS 16293-2422B that suggests that its disk plane is likely located very close to the plane of the sky.Comment: Accepted to ApJ

Impact of acetylation process of kraft lignin in development of environment-friendly semisolid lubricants

The aim of this work was to study the influence of the acetylation process of kraft lignin on developing dispersions potentially applicable as new bio-based semisolid lubricants. Lignin was functionalized with acetic anhydride and pyridine as a catalyst by modifying different reaction variables (temperature, ratio of pyridine/acetic anhydride and time). Acetylated lignin was analyzed using FTIR, 1H and 13C NMR techniques, TGA, DSC and SEM to evaluate the chemical, morphological and thermal changes induced by the acetylation process. The influence of the acetylation process on the rheological and tribological properties of dispersions was related to the development of different microstructures, which depend on chemical and morphological properties of acetylated lignin. In this sense, two different rheological behaviours (gel-like or fluid-like) were found to depend on the reaction time. From the experimental results obtained, it can be concluded that the acetylation process is a key issue to modulate rheological and morphological properties of dispersions, resulting in an effective method to improve the compatibility of lignin and castor oil. Acetylated lignin with medium degrees of substitution with adequate morphological properties can be potentially used as an effective thickening agent to develop semisolid lubricants.This work is part of two research projects, RTI2018-096080-B-C21 and 802C1800001, funded by a Ministerio de Ciencia e Innovación and Junta de Andalucía Spanish programmes, respectively. The authors gratefully acknowledge the financial support.Departamento de Ingeniería Química, Química Física y Ciencias de los Materiale

Relación entre capturas del tiburón Rhizoprionodon terraenovae al sur del Golfo de México y el número de manchas solares

Background. The Antillean or sharpnose shark is one of the main exemplars of shark species in the commercial catch in southern Gulf of Mexico. Oceanic dynamics on the planet Earth varies year-on-year due to the oscillation of solar radiation; fish abundances (and catches) likely respond to these oscillations. Goals. This study focuses on the analysis of landings variability of the antillean sharpnose shark (Rhizoprionodon terraenovae) in the Mexican coast of the Gulf of Mexico, from 1940 to 2006, and its possible connection with solar activity as assessed by the average sunspot number (Zürich Index). Methods. A polynomial curve by least-squares best fitting was used to eliminate the tendency from the sharpnose shark landings time series. Spectral techniques of Maximum Entropy (ME) and Fast Fourier Transform (FFT) were used to analyze the time series of sharpnose shark landings and the Zürich Index. Results. The time series of sharpnose shark landings showed a remarkable spectral peak with a period of about 12.8 years, while the Zürich Index showed a marked peak at a period of 11.6 years. Cross-correlation revealed a delay between the average number of solar spots and sharpnose shark landings. Conclusions. This work is the first to report such a low frequency variability for landings of the Rh. terraenovae fishery in the Gulf of Mexico, using a particular methodology that can provide information for the design of predictive models in the future. The analyzed landing volumes of the sharpnose shark Rh. terraenovae showed as a result a periodical behavior in coincidence with Wolfs solar activity cycle of 10.6 years.Antecedentes. El cazón antillano ó tiburón picudo, es uno de los ejemplares principales de las especies de tiburón en la captura comercial en el sur del Golfo de México. La dinámica oceánica en el planeta tierra varía de forma interanual debido a la oscilación de la radiación solar; las abundancias (y capturas) de peces responden a estas oscilaciones. Objetivos. Analizar la variabilidad de las capturas del cazón antillano Rhizoprionodon terraenovae en el litoral mexicano del Golfo de México, de 1940 a 2006 y su posible relación con la actividad solar, evaluada mediante el número promedio de manchas solares (Índice de Zürich). Métodos. Se empleó el polinomio de mejor ajuste por mínimos cuadrados para eliminar la tendencia de la serie temporal de las capturas; y se utilizaron las técnicas espectrales de la Transformada Rápida de Fourier (FFT) y de Máxima Entropía (ME) para analizar las series temporales de las capturas de cazón y del índice de Zürich. Resultados. Se muestra un pico espectral distintivo en la serie de capturas con una frecuencia de alrededor de 12.8 años, en tanto que el índice de Zürich muestra un pico marcado a los 11.6 años. La correlación cruzada reveló un retraso entre el número promedio de manchas solares y las capturas de tiburón. Conclusiones. Este trabajo es el primero en reportar una frecuencia tan baja en la variabilidad de las capturas de la pesquería de Rh. terraenovae del Golfo de México, empleando una metodología particular que puede proporcionar información para el diseño de modelos predictivos en el futuro. Los volúmenes de captura analizados del cazón antillano Rh. terraenovae mostraron como resultado un comportamiento periódico en coincidencia con el ciclo de actividad solar de Wolf de 10.6 años

The Non-thermal Radio Jet Toward the NGC 2264 Star Formation Region

We report sensitive VLA 3.6 cm radio observations toward the head of the Cone nebula in NGC 2264, made in 2006. The purpose of these observations was to study a non-thermal radio jet recently discovered, that appears to emanate from the head of the Cone nebula. The jet is highly polarized, with well-defined knots, and one-sided. The comparison of our images with 1995 archive data indicates no evidence of proper motions nor polarization changes. We find reliable flux density variations in only one knot, which we tentatively identify as the core of a quasar or radio galaxy. An extragalactic location seems to be the best explanation for this jet.Comment: 12 pages, 5 figure

Proyecto de diseño urbano arquitectónico del centro cultural para el municipio de Santa Elena, Usulután

RESUMEN: Este trabajo de grado presenta la propuesta de diseño del Centro Cultural del Municipio de Santa Elena, Usulután. Se propone el seguimiento de fases de estudio, diagnóstico y conceptualización que permitan el desarrollo de soluciones respecto a la forma y la función del espacio a intervenir. Santa Elena se ubica a 8.3 km de distancia de la ciudad de Usulután, cabecera del departamento homónimo. Esta cercanía ha propiciado la expansión económica y social del municipio, exigiendo que la localidad cuente con el equipamiento urbano idóneo para el desarrollo de diversas actividades, entre ellas las de índole recreativa y cultural. La propuesta de diseño se conceptualiza como arquitectura racionalista, ya que hacemos uso racional del espacio y de la distribución de elementos, incluyendo el entorno topográfico como parte de la edificación, reduciendo el impacto al medioambiente y proporcionado un elemento contrastante al horizonte del municipio. Esta intervención arquitectónica sería la primera de mayor importancia que se realizaría en la localidad. ABSTRACT: This degree thesis is presented the design proposal of the Cultural Center of the Municipality of Santa Elena, Usulután. The follow-up of phases of study, diagnosis and conceptualization that allow the development of solutions accord to the form and function of the space to be intervened is proposed. Santa Elena is located 5.15 mi away from the city of Usulután, capital of the homonymous department. This proximity has led the economic and social expansion of the municipality, requiring the town to have the ideal urban equipment for the development of various activities, including the recreational and cultural ones. The design proposal is conceptualized as rationalist architecture, since we make rational use of space and the distribution of elements, including the topographical environment as part of the building, reducing the impact on the environment and providing a contrasting element to the skyline of the municipality. This architectural intervention would be the first of greatest importance to be carried out in the tow

Antineoplastic effects of the DNA methylation inhibitor hydralazine and the histone deacetylase inhibitor valproic acid in cancer cell lines

BACKGROUND: Among the epigenetic alterations occurring in cancer, DNA hypermethylation and histone hypoacetylation are the focus of intense research because their pharmacological inhibition has shown to produce antineoplastic activity in a variety of experimental models. The objective of this study was to evaluate the combined antineoplastic effect of the DNA methylation inhibitor hydralazine and the histone deacetylase inhibitor valproic acid in a panel of cancer cell lines. RESULTS: Hydralazine showed no growth inhibitory effect on cervical, colon, breast, sarcoma, glioma, and head & neck cancer cell lines when used alone. On the contrary, valproic acid showed a strong growth inhibitory effect that is potentiated by hydralazine in some cell lines. Individually, hydralazine and valproic acid displayed distinctive effects upon global gene over-expression but the number of genes over-expressed increased when cells were treated with the combination. Treatment of HeLa cells with hydralazine and valproic acid lead to an increase in the cytotoxicity of gemcitabine, cisplatin and adriamycin. A higher antitumor effect of adriamycin was observed in mice xenografted with human fibrosarcoma cells when the animals were co-treated with hydralazine and valproic acid. CONCLUSION: Hydralazine and valproic acid, two widely used drugs for cardiovascular and neurological conditions respectively have promising antineoplastic effects when used concurrently and may increase the antitumor efficacy of current cytotoxic agents