High Spectral and Spatial Resolution Observations of the PDR Emission in the NGC2023 Reflection Nebula with SOFIA and APEX

We have mapped the NGC 2023 reflection nebula in [CII] and CO(11--10) with the heterodyne receiver GREAT on SOFIA and obtained slightly smaller maps in 13CO(3--2), CO(3--2), CO(4--3), CO(6--5), and CO(7--6) with APEX in Chile. We use these data to probe the morphology, kinematics, and physical conditions of the C II region, which is ionized by FUV radiation from the B2 star HD37903. The [CII] emission traces an ellipsoidal shell-like region at a position angle of ~ -50 deg, and is surrounded by a hot molecular shell. In the southeast, where the C II region expands into a dense, clumpy molecular cloud ridge, we see narrow and strong line emission from high-J CO lines, which comes from a thin, hot molecular shell surrounding the [CII] emission. The [CII] lines are broader and show photo evaporating gas flowing into the C II region. Based on the strength of the [13CII] F=2--1 line, the [CII] line appears to be somewhat optically thick over most of the nebula with an optical depth of a few. We model the physical conditions of the surrounding molecular cloud and the PDR emission using both RADEX and simple PDR models. The temperature of the CO emitting PDR shell is ~ 90 -- 120 K, with densities of 10^5 -- 10^6 cm^-3, as deduced from RADEX modeling. Our PDR modeling indicates that the PDR layer where [CII] emission dominates has somewhat lower densities, 10^4 to a few times 10^5 cm^-3Comment: Accepted by A&

Multilayer hazes over Saturn’s hexagon from Cassini ISS limb images

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Filtro digital adaptable para sistemas embebidos

Las señales pueden contener distorsiones y ruido que dificultan la lectura en forma correcta de los parámetros requeridos por el usuario, motivo por el cual en la mayoría de los equipos de medida se debe optimizar la medición a través de filtros digitales que procesen la señal [4, 5]. En este trabajo se estudian y diseñan filtros digitales con coeficientes variables, realizando la implementación con circuitos lógicos programables, obteniéndose un dispositivo digital para el análisis de datos muy flexible. La metodología de diseño utilizada (codiseño HARD/SOFT) posibilita la fácil modificación de las características, adaptándolo a sistemas embebidos específicos, brindando la posibilidad inmediata de la implementación del circuito en una ASIC, con la ayuda de las herramientas adecuadas (para nuestro caso CADENCE). Por último se presentan los resultados y conclusiones de la implementación y las distintas posibilidades de uso del dispositivo

Organic Molecules in the Galactic Center. Hot Core Chemistry without Hot Cores

We study the origin of large abundances of complex organic molecules in the Galactic center (GC). We carried out a systematic study of the complex organic molecules CH3OH, C2H5OH, (CH3)2O, HCOOCH3, HCOOH, CH3COOH, H2CO, and CS toward 40 GC molecular clouds. Using the LTE approximation, we derived the physical properties of GC molecular clouds and the abundances of the complex molecules.The CH3OH abundance between clouds varies by nearly two orders of magnitude from 2.4x10^{-8} to 1.1x10^{-6}. The abundance of the other complex organic molecules relative to that of CH3OH is basically independent of the CH3OH abundance, with variations of only a factor 4-8. The abundances of complex organic molecules in the GC are compared with those measured in hot cores and hot corinos, in which these complex molecules are also abundant. We find that both the abundance and the abundance ratios of the complex molecules relative to CH3OH in hot cores are similar to those found in the GC clouds. However, hot corinos show different abundance ratios than observed in hot cores and in GC clouds. The rather constant abundance of all the complex molecules relative to CH3OH suggests that all complex molecules are ejected from grain mantles by shocks. Frequent (similar 10^{5}years) shocks with velocities >6km/s are required to explain the high abundances in gas phase of complex organic molecules in the GC molecular clouds. The rather uniform abundance ratios in the GC clouds and in Galactic hot cores indicate a similar average composition of grain mantles in both kinds of regions. The Sickle and the Thermal Radio Arches, affected by UV radiation, show different relative abundances in the complex organic molecules due to the differentially photodissociation of these molecules.Comment: 18 pages, 10 Postscript figures, uses aa.cls, aa.bst, 10pt.rtx, natbib.sty, revsymb.sty revtex4.cls, aps.rtx and aalongtabl.sty. Accepted in A&A 2006. version 2. relocated figures and tables. Language editor suggestions. added reference

Ionized gas at the edge of the Central Molecular Zone

To determine the properties of the ionized gas at the edge of the CMZ near Sgr E we observed a small portion of the edge of the CMZ near Sgr E with spectrally resolved [C II] 158 micron and [N II] 205 micron fine structure lines at six positions with the GREAT instrument on SOFIA and in [C II] using Herschel HIFI on-the-fly strip maps. We use the [N II] spectra along with a radiative transfer model to calculate the electron density of the gas and the [C II] maps to illuminate the morphology of the ionized gas and model the column density of CO-dark H2. We detect two [C II] and [N II] velocity components, one along the line of sight to a CO molecular cloud at -207 km/s associated with Sgr E and the other at -174 km/s outside the edge of another CO cloud. From the [N II] emission we find that the average electron density is in the range of about 5 to 25 cm{-3} for these features. This electron density is much higher than that of the warm ionized medium in the disk. The column density of the CO-dark H$_2$ layer in the -207 km/s cloud is about 1-2X10{21} cm{-2} in agreement with theoretical models. The CMZ extends further out in Galactic radius by 7 to 14 pc in ionized gas than it does in molecular gas traced by CO. The edge of the CMZ likely contains dense hot ionized gas surrounding the neutral molecular material. The high fractional abundance of N+ and high electron density require an intense EUV field with a photon flux of order 1e6 to 1e7 photons cm{-2} s{-1}, and/or efficient proton charge exchange with nitrogen, at temperatures of order 1e4 K, and/or a large flux of X-rays. Sgr E is a region of massive star formation which are a potential sources of the EUV radiation that can ionize the gas. In addition X-ray sources and the diffuse X-ray emission in the CMZ are candidates for ionizing nitrogen.Comment: 12 pages, 9 figure

Release kinetics of carvacrol and eugenol from poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) films for food packaging applications

[EN] 13 wt.% of active compounds (carvacrol-CA, eugenol-EU) were obtained by spraying the active between PHBV layers and their subsequent adhesion. Release kinetics of CA and EU in food simulants of different polarity was analysed and the films antimicrobial activity was predicted, taking the minimal inhibitory concentration against some foodborne pathogens into account. Overall migration values were also determined. At equilibrium, an almost total release of both CA and EU occurred in 50% ethanol, about 20 and 50% of CA and EU, respectively, was delivered in the more aqueous simulants and 65 70% in fatty systems. The release rate increased when the polarity of aqueous simulants decreased, but it fell markedly in fatty systems. EU was released faster than CA in the less polar simulants, but more slowly in the more aqueous systems.The authors thank the Ministerio de Economía y Competitividad (Spain) for the financial support provided through Project AGL2013-42989-R and AGL2016-76699-R. Author Raquel Requena thanks the Ministry of Education, Culture and Sport (Spain) for the FPU (FPU13/03444) Grant.Requena-Peris, R.; Vargas, M.; Chiralt, A. (2017). Release kinetics of carvacrol and eugenol from poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) films for food packaging applications. European Polymer Journal. 92:185-193. https://doi.org/10.1016/j.eurpolymj.2017.05.008S1851939

Obtaining antimicrobial bilayer starch and polyester-blend films with carvacrol

[EN] Bilayer films using polyester blends (P) and starch (S) were obtained and characterized, incorporating carvacrol as active compound. Carvacrol was incorporated by spraying it between melt blended and compression moulded sheets or through its incorporation into the chloroform P solution used to obtain P cast films. Different PLA-PHBV ratios (75:25 and 65:35) were tested, with and without 15¿wt% of PEG1000, whereas the 75:25 ratio with PEG was only used for cast sheets, based on its better overall properties. Mono and bilayers were characterized as to their tensile and water vapour barrier properties and thermal behaviour. Release kinetics of carvacrol in different food simulants and in in vitro antibacterial activity against Listeria innocua and Escherichia coli were also analysed. Incorporating carvacrol by spraying it between the polyester and starch sheets was not effective at retaining the compound in the bilayers. However, the incorporation of carvacrol into cast P films, and the subsequent formation of bilayers with the S sheets, was highly effective at providing practically total carvacrol retention. These active bilayers exhibited highly improved tensile and water vapour barrier capacity with respect to the S monolayer (87% reduction in WVP, 840% increase in elastic modulus) and inhibited the growth of L. innocua and E. coli from both P or S contact sides of bilayers, depending on the internal diffusion of carvacrol through the bilayer and its adequate release of the compound into the culture medium.Requena-Peris, R.; Vargas, M.; Chiralt, A. (2018). Obtaining antimicrobial bilayer starch and polyester-blend films with carvacrol. Food Hydrocolloids. 83:118-133. https://doi.org/10.1016/j.foodhyd.2018.04.045S1181338

Study of the potential synergistic antibacterial activity of essential oil components using the thiazolyl blue tetrazolium bromide (MTT) assay

[EN] The thiazolyl blue tetrazolium bromide (MTT) assay was used to study the potential interactions between several active compounds from plant essential oils (carvacrol, eugenol, cinnamaldehyde, thymol and eucalyptol) when used as antibacterial agents against Escherichia coli and Listeria innocua. The minimum inhibitory concentration (MIC) of each active compound and the fractional inhibitory concentration (FIC) index for the binary combinations of essential oil compounds were determined. According to FIC index values, some of the compound binary combinations showed an additive effect, but others, such as carvacrol-eugenol and carvacrol-cinnamaldehyde exhibited a synergistic effect against L. innocua and E. coli, which was affected by the compound ratios. Some eugenol-cinnamaldehyde ratios exhibit an antagonistic effect against E. coli, but a synergistic effect against L. innocua. The most remarkable synergistic effect was observed for carvacrol-cinnamaldehyde blends for both E. colt and L. innocua, but using different compound ratios (1:0.1 and 0.5:4 respectively for each bacteria).The authors thank the Ministerio de Economia y Competitividad (Spain) for the financial support provided through Project AGL2016-76699-R. Author Raquel Requena thanks the Ministry of Education, Culture and Sport (Spain) for the FPU (FPU13/03444) Grant.Requena-Peris, R.; Vargas, M.; Chiralt, A. (2019). Study of the potential synergistic antibacterial activity of essential oil components using the thiazolyl blue tetrazolium bromide (MTT) assay. LWT - Food Science and Technology. 101:183-190. https://doi.org/10.1016/j.lwt.2018.10.093S18319010