CH^+(1–0) and ^(13)CH^+(1–0) absorption lines in the direction of massive star-forming regions

We report the detection of the ground-state rotational transition of the methylidyne cation CH^+ and its isotopologue ^(13)CH^+ toward the remote massive star-forming regions W33A, W49N, and W51 with the HIFI instrument onboard the Herschel satellite. Both lines are seen only in absorption against the dust continuum emission of the star-forming regions. The CH^+ absorption is saturated over almost the entire velocity ranges sampled by the lines-of-sight that include gas associated with the star-forming regions (SFR) and Galactic foreground material. The CH^+ column densities are inferred from the optically thin components. A lower limit of the isotopic ratio [^(12)CH^+]/[^(13)CH^+] > 35.5 is derived from the absorptions of foreground material toward W49N. The column density ratio, N(CH^+)/N(HCO^+), is found to vary by at least a factor 10, between 4 and >40, in the Galactic foreground material. Line-of-sight ^(12)CH^+ average abundances relative to total hydrogen are estimated. Their average value, N(CH^+)/N_H > 2.6 × 10^(−8), is higher than that observed in the solar neighborhood and confirms the high abundances of CH^+ in the Galactic interstellar medium. We compare this result to the predictions of turbulent dissipation regions (TDR) models and find that these high abundances can be reproduced for the inner Galaxy conditions. It is remarkable that the range of predicted N(CH^+)/N(HCO^+) ratios, from 1 to ~50, is comparable to that observed

A survey of HC_3N in extragalactic sources: Is HC_3N a tracer of activity in ULIRGs?

Context. HC_3N is a molecule that is mainly associated with Galactic star-forming regions, but it has also been detected in extragalactic environments. Aims. To present the first extragalactic survey of HC_3N, when combining earlier data from the literature with six new single-dish detections, and to compare HC_3N with other molecular tracers (HCN, HNC), as well as other properties (silicate absorption strength, IR flux density ratios, C_(II) flux, and megamaser activity). Methods. We present mm IRAM 30 m, OSO 20 m, and SEST observations of HC_3N rotational lines (mainly the J = 10–9 transition) and of the J = 1–0 transitions of HCN and HNC. Our combined HC_3N data account for 13 galaxies (excluding the upper limits reported for the non-detections), while we have HCN and HNC data for more than 20 galaxies. Results. A preliminary definition “HC_3N-luminous galaxy” is made based upon the HC_3N/HCN ratio. Most (~80%) HC_3N-luminous galaxies seem to be deeply obscured galaxies and (U)LIRGs. A majority (~60% or more) of the HC3N-luminous galaxies in the sample present OH mega- or strong kilomaser activity. A possible explanation is that both HC_3N and OH megamasers need warm dust for their excitation. Alternatively, the dust that excites the OH megamaser offers protection against UV destruction of HC_3N. A high silicate absorption strength is also found in several of the HC_3N-luminous objects, which may help the HC3N to survive. Finally, we find that a high HC_3N/HCN ratio is related to a high dust temperature and a low C_(II) flux

On critical aspects of infiltrated Al/diamond composites for thermal management: Diamond quality versus processing conditions

Al/diamond composites containing diamond particles of different qualities have been manufactured by gas pressure-assisted metal infiltration and characterized by thermal conductivity (TC) measurements. The results show that the intrinsic thermal conductivity of diamond (varied with the diamond quality) plays a minor role on TC. TC is mainly governed by the Al–diamond interface characteristics, which are determined by a proper control exerted through processing conditions. Albeit a very low cost and low quality diamond is used, a high value of 667 W/m K has been measured for Al/diamond composites produced under optimized processing conditions. Values above 740 W/m K are reported for the best diamond quality explored in this work. These experimental results, which assign the control over TC mainly to the interface conductance, suggest that many of the limiting values of TC reported in literature for the different explored metal–diamond systems, need to be reconsidered by proper precise control of interface evolution.The authors acknowledge partial financial support from the Ministerio de Ciencia e Innovación (Projects MAT2011-25029 and AGNO – GRUPOANTOLIN-08Y) and Generalitat Valenciana (Project PROMETEO/2009/002). J.M. Molina wishes also to thank the Ministerio de Ciencia e Innovación for a “Ramón y Cajal” contract. I.E. Monje acknowledges the Universidad de Alicante for a PhD fellowship

Vigilant Keratinocytes Trigger PAMP Signaling in Response to Streptococcal M1 Protein.

The human skin exerts many functions in order to maintain its barrier integrity and protect the host from invading microorganisms. One such pathogen is Streptococcus pyogenes, which can cause a variety of superficial skin wounds that may eventually progress into invasive deep soft tissue infections. Here we show that keratinocytes recognize soluble M1 protein, a streptococcal virulence factor, as a PAMP to release alarming inflammatory responses. We found that this interaction initiates an inflammatory intracellular signaling cascade involving the activation of mitogen-activated kinases, ERK, p38 and JNK, and the subsequent induction and mobilization of the transcription factors NF-κB and AP-1. We also determined the imprint of inflammatory mediators released, such as IL-8, GROα, MIF, EMMPRIN, IL-1α, IL-1Ra, and ST2 in response to streptococcal M1 protein. The expression of IL-8 is dependent on TLR2 activity and subsequent activation of the MAP kinases ERK and p38. Notably this signaling seems distinct for IL-8 release and it is not shared with the other inflammatory mediators. We conclude that keratinocytes participate pro-inflammatory in streptococcal pattern recognition and that expression of the chemoattractant IL-8 by keratinocytes constitutes an important protective mechanism against streptococcal M1 protein

Mechanism of Block of hEag1 K+ Channels by Imipramine and Astemizole

Ether à go-go (Eag; KV10.1) voltage-gated K+ channels have been detected in cancer cell lines of diverse origin and shown to influence their rate of proliferation. The tricyclic antidepressant imipramine and the antihistamine astemizole inhibit the current through Eag1 channels and reduce the proliferation of cancer cells. Here we describe the mechanism by which both drugs block human Eag1 (hEag1) channels. Even if both drugs differ in their affinity for hEag1 channels (IC50s are ∼2 μM for imipramine and ∼200 nM for astemizole) and in their blocking kinetics, both drugs permeate the membrane and inhibit the hEag1 current by selectively binding to open channels. Furthermore, both drugs are weak bases and the IC50s depend on both internal an external pH, suggesting that both substances cross the membrane in their uncharged form and act from inside the cell in their charged forms. Accordingly, the block by imipramine is voltage dependent and antagonized by intracellular TEA, consistent with imipramine binding in its charged form to a site located close to the inner end of the selectivity filter. Using inside- and outside-out patch recordings, we found that a permanently charged, quaternary derivative of imipramine (N-methyl-imipramine) only blocks channels from the intracellular side of the membrane. In contrast, the block by astemizole is voltage independent. However, as astemizole competes with imipramine and intracellular TEA for binding to the channel, it is proposed to interact with an overlapping intracellular binding site. The significance of these findings, in the context of structure–function of channels of the eag family is discussed

Identification of bioactive compounds in diabetes and infertility models of C. elegans

Polycystic ovary syndrome (POS) is a complex and heterogeneous endocrine disease characterized by hyperandrogenism, oligo-anovulation and metabolic disorders, including insulin resistance, obesity and type II diabetes. Additionally, POS causes infertility in childbearing age women, making of great interest the search of new treatments and compounds for the improvement of the symptoms of this chronic disease. Despite the definitive pathological mechanism of POS is still unknown, as mentioned before there is a strong relation between the syndrome and different alterations in the insulin signaling pathway. This pathway is evolutionary conserved and it has a homologue pathway in the organism Caenorhabditis elegans. Mutations in the insulin receptor homologue daf-2 gene or in the phosphatidylinositol 3-kinase (PI3K) homologue age-1, result in reduction of fertility, being the decrease in progeny sharper in the allele age-1(mg305) mutant, in addition to a less pleiotropic effect. We consider this mutant of C. elegans a good model to study the insulin pathway, and specifically POS, due to the high degree of conservation of the pathway and the similarities between the phenotype caused by the mutation and the human symptoms

Herschel observations of interstellar chloronium. II - Detections toward G29.96-0.02, W49N, W51, and W3(OH), and determinations of the ortho-to-para and 35^{35}Cl/37^{37}Cl isotopic ratios

We report additional detections of the chloronium molecular ion, H$_2$Cl$^+$, toward four bright submillimeter continuum sources: G29.96, W49N, W51, and W3(OH). With the use of the HIFI instrument on the Herschel Space Observatory, we observed the $2_{12}-1_{01}$ transition of ortho-H$_2^{35}$Cl$^+$ at 781.627 GHz in absorption toward all four sources. Much of the detected absorption arises in diffuse foreground clouds that are unassociated with the background continuum sources and in which our best estimates of the $N({\rm H_2Cl^+})/N({\rm H})$ ratio lie in the range $(0.9 - 4.8) \times 10^{-9}$. These chloronium abundances relative to atomic hydrogen can exceed the predictions of current astrochemical models by up to a factor of 5. Toward W49N, we have also detected the $2_{12}-1_{01}$ transition of ortho-H$_2^{37}$Cl$^+$ at 780.053 GHz and the $1_{11}-0_{00}$ transition of para-H$_2^{35}$Cl$^+$ at 485.418 GHz. These observations imply $\rm H_2^{35}Cl^+/H_2^{37}Cl^+$ column density ratios that are consistent with the solar system $^{35}$Cl/$^{37}$Cl isotopic ratio of 3.1, and chloronium ortho-to-para ratios consistent with 3, the ratio of spin statistical weights.Comment: 31 pages, including 7 figures. Accepted for publication in the Ap

SIMULACIÓN DE LOS CANALES DE FLUJO PARA UNA CELDA TIPO PEM INSPIRADO EN LA NATURALEZA (SIMULATION OF THE FLOW-FIELD CHANNELS INSPIRED IN THE NATURE FOR A PEM FUEL CELL)

Este trabajo presenta el diseño de un modelo de canal de flujo inspirado en la naturaleza para una Celda de Combustible de Membrana de Intercambio Protónico (PEMFC). Éste canal se diseñó utilizando la derivación de la ley de Murray que está basada en el sistema circulatorio biológico. El comportamiento del gas (oxígeno) en este modelo de canal de flujo se comparará con el modelo paralelo-serpentín. Los análisis de simulación presentados para ambos modelos de canales son: velocidad, presión y temperatura del gas. Tanto el diseño de los modelos como los análisis fueron realizados en el software SolidWorks.  Palabra(s) Clave: Celdas de combustible PEM, Diseño de canales de flujo, Leyes de Murray, Simulación de fluidos. Abstract In this work a design of a flow-field channel inspired in the nature for a Proton Exchange Membrane Fuel Cell (PEMFC) is presented. This flow-field channel was designed using a derivation of the Murray´s Law, which is based on the biological circulatory system. The performance of the gas (oxygen) in this flow-field channel model will be compared with the parallel-serpentine flow-field model. The simulation analyzes for both flow-field channel models presented are: speed, pressure and gas temperature. The models and analyzes were made using SolidWorks software.Keywords: Flow-field channel design, Flow Simulation, Murray law, PEM fuel cells