WARM HCN IN THE PLANET FORMATION ZONE OF GV TAU N

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Fuente, Asuncion [Observatorio Astronomico Nacional (OAN,IGN), Apdo 112, E-28803 Alcala de Henares (Spain); Cernicharo, Jose; Agundez, Marcelino, E-mail: a.fuente@oan.es [Centro de Astrobiologia (CSIC/INTA), Laboratory of Molecular Astrophysics, Ctra. Ajalvir km. 4, E-28850 Torrejon de Ardoz (Spain)

2012-07-20

The Plateau de Bure Interferometer has been used to map the continuum emission at 3.4 mm and 1.1 mm together with the J = 1{yields}0 and J = 3{yields}2 lines of HCN and HCO{sup +} toward the binary star GV Tau. The 3.4 mm observations did not resolve the binary components, and the HCN J = 1{yields}0 and HCO{sup +} J 1{yields}0 line emissions trace the circumbinary disk and the flattened envelope. However, the 1.1 mm observations resolved the individual disks of GV Tau N and GV Tau S and allowed us to study their chemistry. We detected the HCN 3{yields}2 line only toward the individual disk of GV Tau N, and the emission of the HCO{sup +} 3{yields}2 line toward GV Tau S. Simple calculations indicate that the 3{yields}2 line of HCN is formed in the inner R < 12 AU of the disk around GV Tau N where the HCN/HCO{sup +} abundance ratio is >300. On the contrary, this ratio is <1.6 in the disk around GV Tau S. The high HCN abundance measured in GV Tau N is well explained by photochemical processes in the warm (>400 K) and dense (n > 10{sup 7} cm{sup -3}) disk surface.

The Photodissociation of HCN and HNC: Effects on the HNC/HCN Abundance Ratio in the Interstellar Medium

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Aguado, Alfredo [Departamento de Química Física Aplicada (UAM), Unidad Asociada a IFF-CSIC, Facultad de Ciencias Módulo 14, Universidad Autónoma de Madrid, E-28049, Madrid (Spain); Roncero, Octavio; Zanchet, Alexandre [Instituto de Física Fundamental (IFF-CSIC), C.S.I.C., Serrano 123, E-28006 Madrid (Spain); Agúndez, Marcelino; Cernicharo, José, E-mail: octavio.roncero@csic.es [Instituto de Ciencia de Materiales de Madrid, CSIC, C/ Sor Juana Inés de la Cruz 3, Cantoblanco E-28049 (Spain)

2017-03-20

The impact of the photodissociation of HCN and HNC isomers is analyzed in different astrophysical environments. For this purpose, the individual photodissociation cross sections of HCN and HNC isomers have been calculated in the 7–13.6 eV photon energy range for a temperature of 10 K. These calculations are based on the ab initio calculation of three-dimensional adiabatic potential energy surfaces of the 21 lower electronic states. The cross sections are then obtained using a quantum wave packet calculation of the rotational transitions needed to simulate a rotational temperature of 10 K. The cross section calculated for HCN shows significant differences with respect to the experimental one, and this is attributed to the need to consider non-adiabatic transitions. Ratios between the photodissociation rates of HCN and HNC under different ultraviolet radiation fields have been computed by renormalizing the rates to the experimental value. It is found that HNC is photodissociated faster than HCN by a factor of 2.2 for the local interstellar radiation field and 9.2 for the solar radiation field, at 1 au. We conclude that to properly describe the HNC/HCN abundance ratio in astronomical environments illuminated by an intense ultraviolet radiation field, it is necessary to use different photodissociation rates for each of the two isomers, which are obtained by integrating the product of the photodissociation cross sections and ultraviolet radiation field over the relevant wavelength range.

Inferior Olive HCN1 Channels Coordinate Synaptic Integration and Complex Spike Timing

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Derek L.F. Garden

2018-02-01

Full Text Available Cerebellar climbing-fiber-mediated complex spikes originate from neurons in the inferior olive (IO, are critical for motor coordination, and are central to theories of cerebellar learning. Hyperpolarization-activated cyclic-nucleotide-gated (HCN channels expressed by IO neurons have been considered as pacemaker currents important for oscillatory and resonant dynamics. Here, we demonstrate that in vitro, network actions of HCN1 channels enable bidirectional glutamatergic synaptic responses, while local actions of HCN1 channels determine the timing and waveform of synaptically driven action potentials. These roles are distinct from, and may complement, proposed pacemaker functions of HCN channels. We find that in behaving animals HCN1 channels reduce variability in the timing of cerebellar complex spikes, which serve as a readout of IO spiking. Our results suggest that spatially distributed actions of HCN1 channels enable the IO to implement network-wide rules for synaptic integration that modulate the timing of cerebellar climbing fiber signals.

CO and HCN observations of carbon stars

NARCIS (Netherlands)

Baas, F; deJong, T; Loup, C

We present CO and HCN observations of carbon stars. They consist of partly new detections in the (CO)-C-12 J = (1-0), (2-1) and HCN(1-0) lines obtained with the SEST and the IRAM telescope, and of (CO)-C-12 and (CO)-C-13 J = (1-0), (2-1) and (3-2) observations with IRAM and the JCMT of some of the

ALMA HCN AND HCO{sup +} J  = 3 − 2 OBSERVATIONS OF OPTICAL SEYFERT AND LUMINOUS INFRARED GALAXIES: CONFIRMATION OF ELEVATED HCN-TO-HCO{sup +} FLUX RATIOS IN AGNS

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Imanishi, Masatoshi; Nakanishi, Kouichiro [National Astronomical Observatory of Japan, National Institutes of Natural Sciences (NINS), 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Izumi, Takuma, E-mail: masa.imanishi@nao.ac.jp [Institute of Astronomy, School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan)

2016-12-01

We present the results of our ALMA observations of three active galactic nucleus (AGN)-dominated nuclei in optical Seyfert 1 galaxies (NGC 7469, I Zw 1, and IC 4329 A) and eleven luminous infrared galaxies (LIRGs) with various levels of infrared estimated energetic contributions by AGNs at the HCN and HCO{sup +} J  = 3 − 2 emission lines. The HCN and HCO{sup +} J  = 3 − 2 emission lines are clearly detected at the main nuclei of all sources, except for IC 4329 A. The vibrationally excited ( v {sub 2} = 1f) HCN J  = 3 − 2 and HCO{sup +} J  = 3 − 2 emission lines are simultaneously covered, and HCN v {sub 2} = 1f J  = 3 − 2 emission line signatures are seen in the main nuclei of two LIRGs, IRAS 12112+0305 and IRAS 22491–1808, neither of which shows clear buried AGN signatures in the infrared. If the vibrational excitation is dominated by infrared radiative pumping, through the absorption of infrared 14 μ m photons, primarily originating from AGN-heated hot dust emission, then these two LIRGs may contain infrared-elusive, but (sub)millimeter-detectable, extremely deeply buried AGNs. These vibrationally excited emission lines are not detected in the three AGN-dominated optical Seyfert 1 nuclei. However, the observed HCN v {sub 2} = 1f to v  = 0 flux ratios in these optical Seyferts are still consistent with the intrinsic flux ratios in LIRGs with detectable HCN v {sub 2} = 1f emission lines. The observed HCN-to-HCO{sup +} J  = 3 − 2 flux ratios tend to be higher in galactic nuclei with luminous AGN signatures compared with starburst-dominated regions, as previously seen at J  = 1 − 0 and J  = 4 − 3.

WARM HCN IN THE PLANET FORMATION ZONE OF GV TAU N

International Nuclear Information System (INIS)

Fuente, Asunción; Cernicharo, José; Agúndez, Marcelino

2012-01-01

The Plateau de Bure Interferometer has been used to map the continuum emission at 3.4 mm and 1.1 mm together with the J = 1→0 and J = 3→2 lines of HCN and HCO + toward the binary star GV Tau. The 3.4 mm observations did not resolve the binary components, and the HCN J = 1→0 and HCO + J 1→0 line emissions trace the circumbinary disk and the flattened envelope. However, the 1.1 mm observations resolved the individual disks of GV Tau N and GV Tau S and allowed us to study their chemistry. We detected the HCN 3→2 line only toward the individual disk of GV Tau N, and the emission of the HCO + 3→2 line toward GV Tau S. Simple calculations indicate that the 3→2 line of HCN is formed in the inner R + abundance ratio is >300. On the contrary, this ratio is 400 K) and dense (n > 10 7 cm –3 ) disk surface.

HCN Channels—Modulators of Cardiac and Neuronal Excitability

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Stefan Herrmann

2015-01-01

Full Text Available Hyperpolarization-activated cyclic nucleotide-gated (HCN channels comprise a family of cation channels activated by hyperpolarized membrane potentials and stimulated by intracellular cyclic nucleotides. The four members of this family, HCN1–4, show distinct biophysical properties which are most evident in the kinetics of activation and deactivation, the sensitivity towards cyclic nucleotides and the modulation by tyrosine phosphorylation. The four isoforms are differentially expressed in various excitable tissues. This review will mainly focus on recent insights into the functional role of the channels apart from their classic role as pacemakers. The importance of HCN channels in the cardiac ventricle and ventricular hypertrophy will be discussed. In addition, their functional significance in the peripheral nervous system and nociception will be examined. The data, which are mainly derived from studies using transgenic mice, suggest that HCN channels contribute significantly to cellular excitability in these tissues. Remarkably, the impact of the channels is clearly more pronounced in pathophysiological states including ventricular hypertrophy as well as neural inflammation and neuropathy suggesting that HCN channels may constitute promising drug targets in the treatment of these conditions. This perspective as well as the current therapeutic use of HCN blockers will also be addressed.

ORIGINS OF SCATTER IN THE RELATIONSHIP BETWEEN HCN 1-0 AND DENSE GAS MASS IN THE GALACTIC CENTER

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Mills, Elisabeth A. C. [San Jose State University, 1 Washington Square, San Jose, CA 95192 (United States); Battersby, Cara, E-mail: elisabeth.mills@sjsu.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2017-01-20

We investigate the correlation of HCN 1-0 with gas mass in the central 300 pc of the Galaxy. We find that on the ∼10 pc size scale of individual cloud cores, HCN 1-0 is well correlated with dense gas mass when plotted as a log–log relationship. There is ∼0.75 dex of scatter in this relationship from clouds like Sgr B2, which has an integrated HCN 1-0 intensity of a cloud less than half its mass, and others that have HCN 1-0 enhanced by a factor of 2–3 relative to clouds of comparable mass. We identify the two primary sources of scatter to be self-absorption and variations in HCN abundance. We also find that the extended HCN 1-0 emission is more intense per unit mass than in individual cloud cores. In fact the majority (80%) of HCN 1-0 emission comes from extended gas with column densities below 7 × 10{sup 22} cm{sup −2}, accounting for 68% of the total mass. We find variations in the brightness of HCN 1-0 would only yield a ∼10% error in the dense gas mass inferred from this line in the Galactic center. However, the observed order of magnitude HCN abundance variations, and the systematic nature of these variations, warn of potential biases in the use of HCN as dense gas mass tracer in more extreme environments such as an active galactic nucleus and shock-dominated regions. We also investigate other 3 mm tracers, finding that HNCO is better correlated with mass than HCN, and might be a better tracer of cloud mass in this environment.

Niflumic acid alters gating of HCN2 pacemaker channels by interaction with the outer region of S4 voltage sensing domains.

Science.gov (United States)

Cheng, Lan; Sanguinetti, Michael C

2009-05-01

Niflumic acid, 2-[[3-(trifluoromethyl)phenyl]amino]pyridine-3-carboxylic acid (NFA), is a nonsteroidal anti-inflammatory drug that also blocks or modifies the gating of many ion channels. Here, we investigated the effects of NFA on hyperpolarization-activated cyclic nucleotide-gated cation (HCN) pacemaker channels expressed in X. laevis oocytes using site-directed mutagenesis and the two-electrode voltage-clamp technique. Extracellular NFA acted rapidly and caused a slowing of activation and deactivation and a hyperpolarizing shift in the voltage dependence of HCN2 channel activation (-24.5 +/- 1.2 mV at 1 mM). Slowed channel gating and reduction of current magnitude was marked in oocytes treated with NFA, while clamped at 0 mV but minimal in oocytes clamped at -100 mV, indicating the drug preferentially interacts with channels in the closed state. NFA at 0.1 to 3 mM shifted the half-point for channel activation in a concentration-dependent manner, with an EC(50) of 0.54 +/- 0.068 mM and a predicted maximum shift of -38 mV. NFA at 1 mM also reduced maximum HCN2 conductance by approximately 20%, presumably by direct block of the pore. The rapid onset and state-dependence of NFA-induced changes in channel gating suggests an interaction with the extracellular region of the S4 transmembrane helix, the primary voltage-sensing domain of HCN2. Neutralization (by mutation to Gln) of any three of the outer four basic charged residues in S4, but not single mutations, abrogated the NFA-induced shift in channel activation. We conclude that NFA alters HCN2 gating by interacting with the extracellular end of the S4 voltage sensor domains.

HCN Channels Modulators: The Need for Selectivity

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Romanelli, Maria Novella; Sartiani, Laura; Masi, Alessio; Mannaioni, Guido; Manetti, Dina; Mugelli, Alessandro; Cerbai, Elisabetta

2016-01-01

Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels, the molecular correlate of the hyperpolarization-activated current (If/Ih), are membrane proteins which play an important role in several physiological processes and various pathological conditions. In the Sino Atrial Node (SAN) HCN4 is the target of ivabradine, a bradycardic agent that is, at the moment, the only drug which specifically blocks If. Nevertheless, several other pharmacological agents have been shown to modulate HCN channels, a property that may contribute to their therapeutic activity and/or to their side effects. HCN channels are considered potential targets for developing drugs to treat several important pathologies, but a major issue in this field is the discovery of isoform-selective compounds, owing to the wide distribution of these proteins into the central and peripheral nervous systems, heart and other peripheral tissues. This survey is focused on the compounds that have been shown, or have been designed, to interact with HCN channels and on their binding sites, with the aim to summarize current knowledge and possibly to unveil useful information to design new potent and selective modulators. PMID:26975509

Biomolecules from HCN

Science.gov (United States)

Ferris, J. P.; Wos, J. D.; Ryan, T. J.; Lobo, A. P.; Donner, D. B.

1974-01-01

It has been suggested by Sanchez et al. (1967) that HCN might have been one of the more important precursors of biological molecules on the primitive earth. Studies were conducted to determine the mechanisms involved in HCN oligomerizations in dilute aqueous solutions and to identify the compounds which are produced in these oligomerization mixtures. Indirect evidence for the formation of cyanate was obtained along with direct evidence for the formation of citrulline, aspartic acid, and orotic acid.

Enhancement of Spontaneous Activity by HCN4 Overexpression in Mouse Embryonic Stem Cell-Derived Cardiomyocytes - A Possible Biological Pacemaker.

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Yukihiro Saito

Full Text Available Establishment of a biological pacemaker is expected to solve the persisting problems of a mechanical pacemaker including the problems of battery life and electromagnetic interference. Enhancement of the funny current (If flowing through hyperpolarization-activated cyclic nucleotide-gated (HCN channels and attenuation of the inward rectifier K+ current (IK1 flowing through inward rectifier potassium (Kir channels are essential for generation of a biological pacemaker. Therefore, we generated HCN4-overexpressing mouse embryonic stem cells (mESCs and induced cardiomyocytes that originally show poor IK1 currents, and we investigated whether the HCN4-overexpressing mESC-derived cardiomyocytes (mESC-CMs function as a biological pacemaker in vitro.The rabbit Hcn4 gene was transfected into mESCs, and stable clones were selected. mESC-CMs were generated via embryoid bodies and purified under serum/glucose-free and lactate-supplemented conditions. Approximately 90% of the purified cells were troponin I-positive by immunostaining. In mESC-CMs, expression level of the Kcnj2 gene encoding Kir2.1, which is essential for generation of IK1 currents that are responsible for stabilizing the resting membrane potential, was lower than that in an adult mouse ventricle. HCN4-overexpressing mESC-CMs expressed about a 3-times higher level of the Hcn4 gene than did non-overexpressing mESC-CMs. Expression of the Cacna1h gene, which encodes T-type calcium channel and generates diastolic depolarization in the sinoatrial node, was also confirmed. Additionally, genes required for impulse conduction including Connexin40, Connexin43, and Connexin45 genes, which encode connexins forming gap junctions, and the Scn5a gene, which encodes sodium channels, are expressed in the cells. HCN4-overexpressing mESC-CMs showed significantly larger If currents and more rapid spontaneous beating than did non-overexpressing mESC-CMs. The beating rate of HCN4-overexpressing mESC-CMs responded

Hydrogen constituents of the mesosphere inferred from positive ions - H2O, CH4, H2CO, H2O2, and HCN

Science.gov (United States)

Kopp, E.

1990-01-01

The concentrations in the mesosphere of H2O, CH4, H2CO, H2O2, and HCN were inferred from data on positive ion compositions, obtained from one mid-latitude and four high-latitude rocket flights. The inferred concentrations were found to agree only partially with the ground-based microwave measurements and/or model prediction by Garcia and Solomon (1985). The CH4 concentration was found to vary between 70 and 4 ppb in daytime and 900 and 100 ppbv at night, respectively. Unexpectedly high H2CO concentrations were obtained, with H2CO/H2O ratios between 0.0006 and 0.1, and a mean HCN volume mixing ratio of 6 x 10 to the -10th was inferred.

ALMA OBSERVATIONS OF HCN AND ITS ISOTOPOLOGUES ON TITAN

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Molter, Edward M.; Nixon, C. A.; Cordiner, M. A.; Charnley, S. B.; Lindberg, J. E. [NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Serigano, J. [Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218 (United States); Irwin, P. G. J. [Atmospheric, Oceanic, and Planetary Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford, OX1 3PU (United Kingdom); Teanby, N. A., E-mail: edward.m.molter@nasa.gov [School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol, BS8 1RJ (United Kingdom)

2016-08-01

We present sub-millimeter spectra of HCN isotopologues on Titan, derived from publicly available ALMA flux calibration observations of Titan taken in early 2014. We report the detection of a new HCN isotopologue on Titan, H{sup 13}C{sup 15}N, and confirm an earlier report of detection of DCN. We model high signal-to-noise observations of HCN, H{sup 13}CN, HC{sup 15}N, DCN, and H{sup 13}C{sup 15}N to derive abundances and infer the following isotopic ratios: {sup 12}C/{sup 13}C = 89.8 ± 2.8, {sup 14}N/{sup 15}N = 72.3 ± 2.2, D/H = (2.5 ± 0.2) × 10{sup −4}, and HCN/H{sup 13}C{sup 15}N = 5800 ± 270 (1 σ errors). The carbon and nitrogen ratios are consistent with and improve on the precision of previous results, confirming a factor of ∼2.3 elevation in {sup 14}N/{sup 15}N in HCN compared to N{sub 2} and a lack of fractionation in {sup 12}C/{sup 13}C from the protosolar value. This is the first published measurement of D/H in a nitrile species on Titan, and we find evidence for a factor of ∼2 deuterium enrichment in hydrogen cyanide compared to methane. The isotopic ratios we derive may be used as constraints for future models to better understand the fractionation processes occurring in Titan’s atmosphere.

Probing highly obscured, self-absorbed galaxy nuclei with vibrationally excited HCN

Science.gov (United States)

Aalto, S.; Martín, S.; Costagliola, F.; González-Alfonso, E.; Muller, S.; Sakamoto, K.; Fuller, G. A.; García-Burillo, S.; van der Werf, P.; Neri, R.; Spaans, M.; Combes, F.; Viti, S.; Mühle, S.; Armus, L.; Evans, A.; Sturm, E.; Cernicharo, J.; Henkel, C.; Greve, T. R.

2015-12-01

We present high resolution (0.̋4) IRAM PdBI and ALMA mm and submm observations of the (ultra) luminous infrared galaxies ((U)LIRGs) IRAS 17208-0014, Arp220, IC 860 and Zw049.057 that reveal intense line emission from vibrationally excited (ν2 = 1) J = 3-2 and 4-3 HCN. The emission is emerging from buried, compact (r 5 × 1013 L⊙ kpc-2. These nuclei are likely powered by accreting supermassive black holes (SMBHs) and/or hot (>200 K) extreme starbursts. Vibrational, ν2 = 1, lines of HCN are excited by intense 14 μm mid-infrared emission and are excellent probes of the dynamics, masses, and physical conditions of (U)LIRG nuclei when H2 column densities exceed 1024 cm-2. It is clear that these lines open up a new interesting avenue to gain access to the most obscured AGNs and starbursts. Vibrationally excited HCN acts as a proxy for the absorbed mid-infrared emission from the embedded nuclei, which allows for reconstruction of the intrinsic, hotter dust SED. In contrast, we show strong evidence that the ground vibrational state (ν = 0), J = 3-2and 4-3 rotational lines of HCN and HCO+ fail to probe the highly enshrouded, compact nuclear regions owing to strong self- and continuum absorption. The HCN and HCO+ line profiles are double-peaked because of the absorption and show evidence of non-circular motions - possibly in the form of in- or outflows. Detections of vibrationally excited HCN in external galaxies are so far limited to ULIRGs and early-type spiral LIRGs, and we discuss possible causes for this. We tentatively suggest that the peak of vibrationally excited HCN emission is connected to a rapid stage of nuclear growth, before the phase of strong feedback. Based on observations carried out with the IRAM Plateau de Bure and ALMA Interferometers. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan), together with NRC (Canada) and NSC and ASIAA

Ammonothermal synthesis of alkali-alkaline earth metal and alkali-rare earth metal carbodiimides. K{sub 5-x}M{sub x}(CN{sub 2}){sub 2+x}(HCN{sub 2}){sub 1-x} (M = Sr, Eu) and Na{sub 4.32}Sr{sub 0.68}(CN{sub 2}){sub 2.68}(HCN{sub 2}){sub 0.32}

Energy Technology Data Exchange (ETDEWEB)

Mallmann, Mathias; Haeusler, Jonas; Cordes, Niklas; Schnick, Wolfgang [Department of Chemistry, University of Munich (LMU) (Germany)

2017-12-13

Alkali-alkaline earth metal and alkali-rare earth metal carbodiimides, namely K{sub 5-x}M{sub x}(CN{sub 2}){sub 2+x}(HCN{sub 2}){sub 1-x} (x = 0 - 1) (M = Sr, Eu) and Na{sub 4.32}Sr{sub 0.68}(CN{sub 2}){sub 2.68}(HCN{sub 2}){sub 0.32}, were synthesized under ammonothermal conditions in high-pressure autoclaves. The structures of the three compounds can be derived from homeotypic K{sub 5}H(CN{sub 2}){sub 3} and Na{sub 5}H(CN{sub 2}){sub 3} by partial substitution of K{sup +} or Na{sup +}by Sr{sup 2+} or Eu{sup 2+}. The reactions were carried out in two step syntheses (T{sub 1} = 673 K, T{sub 2} = 823 K) starting from sodium or potassium azide, dicyandiamide and strontium or Eu(NH{sub 2}){sub 2}, respectively. The crystal structures were solved and refined from single-crystal X-ray diffraction data [K{sub 4.16}Sr{sub 0.84}(CN{sub 2}){sub 2.84}(HCN{sub 2}){sub 0.16}: space group Im3m (no. 229), a = 7.8304(5) Aa, Z = 2, R{sub 1} = 0.024, wR{sub 2} = 0.052; K{sub 4.40}Eu{sub 0.60}(CN{sub 2}){sub 2.60}(HCN{sub 2}){sub 0.40}: space group Im anti 3m (no. 229), a = 7.8502(6) Aa, Z = 2, R{sub 1} = 0.022, wR{sub 2} = 0.049]. In contrast to the potassium carbodiimides, the sodium-strontium carbodiimide was only synthesized as microcrystalline powder. The crystal structure was determined by powder X-ray diffraction and refined by the Rietveld method [Na{sub 4.32}Sr{sub 0.68}(CN{sub 2}){sub 2.68}(HCN{sub 2}){sub 0.32}: space group Im3m (no. 229), a = 7.2412(1) Aa, Z = 2, R{sub wp} = 0.050]. The presence of hydrogencyanamide units ([HNCN]{sup -}) next to carbodiimide units ([CN{sub 2}]{sup 2-}) in all compounds was confirmed by FT-IR spectroscopy. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Disturbed Processing of Contextual Information in HCN3 Channel Deficient Mice

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Marc S. Stieglitz

2018-01-01

Full Text Available Hyperpolarization-activated cyclic nucleotide-gated channels (HCNs in the nervous system are implicated in a variety of neuronal functions including learning and memory, regulation of vigilance states and pain. Dysfunctions or genetic loss of these channels have been shown to cause human diseases such as epilepsy, depression, schizophrenia, and Parkinson's disease. The physiological functions of HCN1 and HCN2 channels in the nervous system have been analyzed using genetic knockout mouse models. By contrast, there are no such genetic studies for HCN3 channels so far. Here, we use a HCN3-deficient (HCN3−/− mouse line, which has been previously generated in our group to examine the expression and function of this channel in the CNS. Specifically, we investigate the role of HCN3 channels for the regulation of circadian rhythm and for the determination of behavior. Contrary to previous suggestions we find that HCN3−/− mice show normal visual, photic, and non-photic circadian function. In addition, HCN3−/− mice are impaired in processing contextual information, which is characterized by attenuated long-term extinction of contextual fear and increased fear to a neutral context upon repeated exposure.

Disturbed Processing of Contextual Information in HCN3 Channel Deficient Mice

Science.gov (United States)

Stieglitz, Marc S.; Fenske, Stefanie; Hammelmann, Verena; Becirovic, Elvir; Schöttle, Verena; Delorme, James E.; Schöll-Weidinger, Martha; Mader, Robert; Deussing, Jan; Wolfer, David P.; Seeliger, Mathias W.; Albrecht, Urs; Wotjak, Carsten T.; Biel, Martin; Michalakis, Stylianos; Wahl-Schott, Christian

2018-01-01

Hyperpolarization-activated cyclic nucleotide-gated channels (HCNs) in the nervous system are implicated in a variety of neuronal functions including learning and memory, regulation of vigilance states and pain. Dysfunctions or genetic loss of these channels have been shown to cause human diseases such as epilepsy, depression, schizophrenia, and Parkinson's disease. The physiological functions of HCN1 and HCN2 channels in the nervous system have been analyzed using genetic knockout mouse models. By contrast, there are no such genetic studies for HCN3 channels so far. Here, we use a HCN3-deficient (HCN3−/−) mouse line, which has been previously generated in our group to examine the expression and function of this channel in the CNS. Specifically, we investigate the role of HCN3 channels for the regulation of circadian rhythm and for the determination of behavior. Contrary to previous suggestions we find that HCN3−/− mice show normal visual, photic, and non-photic circadian function. In addition, HCN3−/− mice are impaired in processing contextual information, which is characterized by attenuated long-term extinction of contextual fear and increased fear to a neutral context upon repeated exposure. PMID:29375299

Genetic variation in Hyperpolarization-activated cyclic nucleotide-gated (HCN channels and its relationship with neuroticism, cognition and risk of depression

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Andrew Mark Mcintosh

2012-07-01

Full Text Available Hyperpolarization-activated cyclic nucleotide-gated (HCN channels are encoded by four genes (HCN1-4 and, through activation by cyclic AMP (cAMP, represent a point of convergence for several psychosis risk genes. On the basis of positive preliminary data, we sought to test whether genetic variation in HCN1-4 conferred risk of depression or cognitive impairment in the Generation Scotland: Scottish Family Health Study. HCN1, HCN2, HCN3 and HCN4 were genotyped for 43 haplotype-tagging SNPs and tested for association with DSM-IV depression, neuroticism and a battery of cognitive tests assessing cognitive ability, memory, verbal fluency and psychomotor performance. No association was found between any HCN channel gene SNP and risk of depression, neuroticism or on any cognitive measure. The current study does not support a genetic role for HCN channels in conferring risk of depression or cognitive impairment in human subjects within the Scottish population.

Photochemistry of methane and the formation of hydrocyanic acid (HCN) in the earth's early atmosphere

Science.gov (United States)

Zahnle, K. J.

1986-01-01

A one-dimensional photochemical model is used to analyze the photochemistries of CH4 and HCN in the primitive terrestrial atmosphere. CH4, N2, and HCN photolysis are examined. The background atmosphere and boundary conditions applied in the analysis are described. The formation of HCN as a by-product of N2 and CH4 photolysis is investigated; the effects of photodissociation and rainfall on HCN is discussed. The low and high CH4 mixing ratios and radical densities are studied.

ALMA DETECTION OF THE VIBRATIONALLY EXCITED HCN J = 4-3 EMISSION LINE IN THE AGN-HOSTING LUMINOUS INFRARED GALAXY IRAS 20551–4250

Energy Technology Data Exchange (ETDEWEB)

Imanishi, Masatoshi [Subaru Telescope, 650 North A' ohoku Place, Hilo, Hawaii, 96720 (United States); Nakanishi, Kouichiro, E-mail: masa.imanishi@nao.ac.jp [Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura 763-0355, Santiago de Chile (Chile)

2013-10-01

We present results from our ALMA Cycle 0 observations, at the frequencies around the HCN, HCO{sup +}, and HNC J = 4-3 transition lines, of the luminous infrared galaxy IRAS 20551–4250 at z = 0.043, which is known to host an energetically important obscured active galactic nucleus (AGN). In addition to the targeted HCN, HCO{sup +}, and HNC J = 4-3 emission lines, two additional strong emission lines are seen, which we attribute to H{sub 2}S and CH{sub 3}CN(+CCH). The HCN-to-HCO{sup +} J = 4-3 flux ratio (∼0.7) is higher than in the other starburst-dominated galaxy (∼0.2) observed in our ALMA Cycle 0 program. We tentatively (∼5σ) detected the vibrationally excited (v {sub 2} = 1) HCN J = 4-3 (l = 1f) emission line, which is important for testing an infrared radiative pumping scenario for HCN. This is the second detection of this molecular transition in external galaxies. The most likely reason for this detection is not only the high flux of this emission line, but also the small molecular line widths observed in this galaxy, suggesting that vibrational excitation of HCN may be relatively common in AGN-hosting galaxies.

Small functional If current in sinoatrial pacemaker cells of the brown trout (Salmo trutta fario) heart despite strong expression of HCN channel transcripts.

Science.gov (United States)

Hassinen, Minna; Haverinen, Jaakko; Vornanen, Matti

2017-12-01

Funny current ( I f ), formed by hyperpolarization-activated cyclic nucleotide-gated channels (HCN channels), is supposed to be crucial for the membrane clock regulating the cardiac pacemaker mechanism. We examined the presence and activity of HCN channels in the brown trout ( Salmo trutta fario ) sinoatrial (SA) pacemaker cells and their putative role in heart rate ( f H ) regulation. Six HCN transcripts (HCN1, HCN2a, HCN2ba, HCN2bb, HCN3, and HCN4) were expressed in the brown trout heart. The total HCN transcript abundance was 4.0 and 4.9 times higher in SA pacemaker tissue than in atrium and ventricle, respectively. In the SA pacemaker, HCN3 and HCN4 were the main isoforms representing 35.8 ± 2.7 and 25.0 ± 1.5%, respectively, of the total HCN transcripts. Only a small I f with a mean current density of -1.2 ± 0.37 pA/pF at -140 mV was found in 4 pacemaker cells out of 16 spontaneously beating cells examined, despite the optimization of recording conditions for I f activity. I f was not found in any of the 24 atrial myocytes and 21 ventricular myocytes examined. HCN4 coexpressed with the MinK-related peptide 1 (MiRP1) β-subunit in CHO cells generated large I f currents. In contrast, HCN3 (+MiRP1) failed to produce I f in the same expression system. Cs + (2 mM), which blocked 84 ± 12% of the native I f , reversibly reduced f H 19.2 ± 3.6% of the excised multicellular pacemaker tissue from 53 ± 5 to 44 ± 5 beats/min ( P brown trout heart is largely independent on I f . Copyright © 2017 the American Physiological Society.

An N-Terminal ER Export Signal Facilitates the Plasma Membrane Targeting of HCN1 Channels in Photoreceptors.

Science.gov (United States)

Pan, Yuan; Laird, Joseph G; Yamaguchi, David M; Baker, Sheila A

2015-06-01

Hyperpolarization-activated cyclic nucleotide-gated 1 (HCN1) channels are widely expressed in the retina. In photoreceptors, the hyperpolarization-activated current (Ih) carried by HCN1 is important for shaping the light response. It has been shown in multiple systems that trafficking HCN1 channels to specific compartments is key to their function. The localization of HCN1 in photoreceptors is concentrated in the plasma membrane of the inner segment (IS). The mechanisms controlling this localization are not understood. We previously identified a di-arginine endoplasmic reticulum (ER) retention motif that negatively regulates the surface targeting of HCN1. In this study, we sought to identify a forward trafficking signal that could counter the function of the ER retention signal. We studied trafficking of HCN1 and several mutants by imaging their subcellular localization in transgenic X. laevis photoreceptors. Velocity sedimentation was used to assay the assembly state of HCN1 channels. We found the HCN1 N-terminus can redirect a membrane reporter from outer segments (OS) to the plasma membrane of the IS. The sequence necessary for this behavior was mapped to a 20 amino acid region containing a leucine-based ER export motif. The ER export signal is necessary for forward trafficking but not channel oligomerization. Moreover, this ER export signal alone counteracted the di-arginine ER retention signal. We identified an ER export signal in HCN1 that functions with the ER retention signal to maintain equilibrium of HCN1 between the endomembrane system and the plasma membrane.

Health Code Number (HCN) Development Procedure

Energy Technology Data Exchange (ETDEWEB)

Petrocchi, Rocky; Craig, Douglas K.; Bond, Jayne-Anne; Trott, Donna M.; Yu, Xiao-Ying

2013-09-01

This report provides the detailed description of health code numbers (HCNs) and the procedure of how each HCN is assigned. It contains many guidelines and rationales of HCNs. HCNs are used in the chemical mixture methodology (CMM), a method recommended by the department of energy (DOE) for assessing health effects as a result of exposures to airborne aerosols in an emergency. The procedure is a useful tool for proficient HCN code developers. Intense training and quality assurance with qualified HCN developers are required before an individual comprehends the procedure to develop HCNs for DOE.

SPATIALLY RESOLVED HCN ABSORPTION FEATURES IN THE CIRCUMNUCLEAR REGION OF NGC 1052

Energy Technology Data Exchange (ETDEWEB)

Sawada-Satoh, Satoko [Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, 2-12 Hoshigaoka-cho, Mizusawa-ku, Oshu, Iwate 023-0861 (Japan); Roh, Duk-Gyoo; Oh, Se-Jin; Lee, Sang-Sung; Byun, Do-Young; Yeom, Jae-Hwan; Jung, Dong-Kyu; Kim, Hyo-Ryoung; Hwang, Ju-Yeon [Korea Astronomy and Space Science Institute, 776 Daedeok-daero, Yuseong, Daejeon 34055 (Korea, Republic of); Kameno, Seiji, E-mail: satoko.ss@nao.ac.jp, E-mail: sss@mx.ibaraki.ac.jp [Joint ALMA Observatory, Alonso de Cordova 3107 Vitacura, Santiago 763 0355 (Chile)

2016-10-10

We present the first VLBI detection of HCN molecular absorption in the nearby active galactic nucleus NGC 1052. Utilizing the 1 mas resolution achieved by the Korean VLBI Network, we have spatially resolved the HCN absorption against a double-sided nuclear jet structure. Two velocity features of HCN absorption are detected significantly at the radial velocity of 1656 and 1719 km s{sup −1}, redshifted by 149 and 212 km s{sup −1} with respect to the systemic velocity of the galaxy. The column density of the HCN molecule is estimated to be 10{sup 15}–10{sup 16} cm{sup −2}, assuming an excitation temperature of 100–230 K. The absorption features show high optical depth localized on the receding jet side, where the free–free absorption occurred due to the circumnuclear torus. The size of the foreground absorbing molecular gas is estimated to be on approximately one-parsec scales, which agrees well with the approximate size of the circumnuclear torus. HCN absorbing gas is likely to be several clumps smaller than 0.1 pc inside the circumnuclear torus. The redshifted velocities of the HCN absorption features imply that HCN absorbing gas traces ongoing infall motion inside the circumnuclear torus onto the central engine.

The HNC/HCN ratio in star-forming regions

International Nuclear Information System (INIS)

Graninger, Dawn M.; Öberg, Karin I.; Herbst, Eric; Vasyunin, Anton I.

2014-01-01

HNC and HCN, typically used as dense gas tracers in molecular clouds, are a pair of isomers that have great potential as a temperature probe because of temperature dependent, isomer-specific formation and destruction pathways. Previous observations of the HNC/HCN abundance ratio show that the ratio decreases with increasing temperature, something that standard astrochemical models cannot reproduce. We have undertaken a detailed parameter study on which environmental characteristics and chemical reactions affect the HNC/HCN ratio and can thus contribute to the observed dependence. Using existing gas and gas-grain models updated with new reactions and reaction barriers, we find that in static models the H + HNC gas-phase reaction regulates the HNC/HCN ratio under all conditions, except for very early times. We quantitatively constrain the combinations of H abundance and H + HNC reaction barrier that can explain the observed HNC/HCN temperature dependence and discuss the implications in light of new quantum chemical calculations. In warm-up models, gas-grain chemistry contributes significantly to the predicted HNC/HCN ratio and understanding the dynamics of star formation is therefore key to model the HNC/HCN system.

Effect of Non-specific HCN1 Blocker CsCl on Spatial Learning and Memory in Mouse

Institute of Scientific and Technical Information of China (English)

YU Xin; GUO Lianjun; YIN Guangfu; ZONG Xiangang; AI Yongxun

2006-01-01

It has been suggested that HCN1 is primarily expressed in hippocampus, however little is known about its effects on spatial learning and memory. In the present study, we investigated the effects of non-specific HCN1 blocker CsCl on spatial learning and memory by using Morris water maze and in situ hybridization in mice. The results showed CsCl 160 mg/kg ip for 4 days, and the mean escape latency was 34 s longer than that of normal control (P＜0.01). In hippocampal tissues, staining for the HCN1 mRNA was stronger in the DG and CA1 region of the hippocampus (P ＜0.05, P＜0.05, when CsCl-administration group was compared with normal group). Our results suggested that CsCl could significantly affect the spatial learning and memory in mice, and HCN channel is involved in the process of learning and memory.

Detection of HCN and C2H2 in ISO Spectra of Oxygen-Rich AGB Stars

Science.gov (United States)

Carbon, Duane F.; Chiar, Jean; Goorvitch, David; Kwak, Dochan (Technical Monitor)

2002-01-01

Cool oxygen-rich AGB stars were not expected to have organic molecules like HCN in either their photospheres or circumstellar envelopes (CSEs). The discovery of HCN and CS microwave emission from the shallowest CSE layers of these stars was a considerable surprise and much theoretical effort has been expended in explaining the presence of such organics. To further explore this problem, we have undertaken a systematic search of oxygen-rich AGB stellar spectra in the Infrared Space Observatory (ISO) data archive. Our purposes are to find evidence regarding critical molecular species that could be of value in choosing among the proposed theoretical models, to locate spectral features which might give clues to conditions deeper in the CSEs, and to lay the groundwork for future SIRTF (Space Infrared Telescope Facility) and SOFIA (Stratospheric Observatory for Infrared Astronomy) observations. Using carefully reduced observations, we have detected weak absorption features arising from HCN and possibly C2H2 in a small number of oxygen-rich AGB stars. The most compelling case is NML Cyg which shows both HCN (14 microns) and CO2 (15 microns). VY CMa, a similar star, shows evidence for HCN, but not CO2. Two S-type stars show evidence for the C-H bending transitions: W Aql at 14 microns (HCN) and both W Aql and S Cas at 13.7 microns (C2H2). Both W Aql and S Cas as well as S Lyr, a SC-type star, show 3 micron absorption which may arise from the C-H stretch of HCN and C2H2. In the case of NML Cyg, we show that the HCN and CO2 spectral features are formed in the CSE at temperatures well above those of the outermost CSE layers and derive approximate column densities. In the case of the S-stars, we discuss the evidence for the organic features and their photospheric origin.

The excitation of HCN and HCO{sup +} in the galactic center circumnuclear disk

Energy Technology Data Exchange (ETDEWEB)

Mills, E. A. C. [National Radio Astronomy Observatory, P.O. Box O 1009, Lopezville Drive, Socorro, NM 87801 (United States); Güsten, R.; Requena-Torres, M. A. [Max Planck Institut für Radioastronomie, Auf Dem Huegel 69, D-53121 Bonn (Germany); Morris, M. R., E-mail: millsb@astro.ucla.edu [Department of Physics and Astronomy, University of California, Physics and Astronomy Building, 430 Portola Plaza, Box 951547 Los Angeles, CA 90095-1547 (United States)

2013-12-10

We present new observations of HCN and HCO{sup +} in the circumnuclear disk (CND) of the Galaxy, which we obtained with the Atacama Pathfinder Experiment telescope. We mapped emission in rotational lines of HCN J = 3-2, 4-3, and 8-7, as well as of HCO{sup +} J = 3-2, 4-3, and 9-8. We also present spectra of H{sup 13}CN J = 3-2 and 4-3 as well as H{sup 13}CO{sup +} J = 3-2 and 4-3 toward four positions in the CND. Using the intensities of all of these lines, we present an excitation analysis for each molecule using the non-LTE radiative transfer code RADEX. The HCN line intensities toward the northern emission peak of the CND yield log densities (cm{sup –3}) of 5.6{sub −0.6}{sup +0.6}, consistent with those measured with HCO{sup +} as well as with densities recently reported for this region from an excitation analysis of highly excited lines of CO. These densities are too low for the gas to be tidally stable. The HCN line intensities toward the CND's southern emission peak yield log densities of 6.5{sub −0.7}{sup +0.5}, higher than densities determined for this part of the CND with CO (although the densities measured with HCO{sup +}, log [n] = 5.6{sub −0.2}{sup +0.2}, are more consistent with the CO-derived densities). We investigate whether the higher densities we infer from HCN are affected by midinfrared radiative excitation of this molecule through its 14 μm rovibrational transitions. We find that radiative excitation is important for at least one clump in the CND, where we additionally detect the J = 4-3, v {sub 2} = 1 vibrationally excited transition of HCN, which is excited by dust temperatures of ≳125-150 K. If this hot dust is present elsewhere in the CND, it could lower our inferred densities, potentially bringing the HCN-derived densities for the southern part of the CND into agreement with those measured using HCO{sup +} and CO. Additional sensitive, high-resolution submillimeter observations, as well as midinfrared observations, would be

The Puzzle of HCN in Comets: Is it both a Product and a Primary Species?

Science.gov (United States)

Mumma, Michael J.; Bonev, Boncho P.; Charnley, Steven B.; Cordiner, Martin A.; DiSanti, Michael A.; Gibb, Erika L.; Magee-Sauer, Karen; Paganini, Lucas; Villanueva, Geronimo L.

2014-11-01

Hydrogen cyanide has long been regarded as a primary volatile in comets, stemming from its presence in dense molecular cloud cores and its supposed storage in the cometary nucleus. Here, we examine the observational evidence for and against that hypothesis, and argue that HCN may also result from near-nucleus chemical reactions in the coma. The distinction (product vs. primary species) is important for multiple reasons: 1. HCN is often used as a proxy for water when the dominant species (H2O) is not available for simultaneous measurement, as at radio wavelengths. 2. HCN is one of the few volatile carriers of nitrogen accessible to remote sensing. If HCN is mainly a product species, its precursor becomes the more important metric for compiling a taxonomic classification based on nitrogen chemistry. 3. The stereoisomer HNC is now confirmed as a product species. Could reaction of a primary precursor (X-CN) with a hydrocarbon co-produce both HNC and HCN? 4. The production rate for CN greatly exceeds that of HCN in some comets, demonstrating the presence of another (more important) precursor of CN. Several puzzling lines of evidence raise issues about the origin of HCN: a. The production rates of HCN measured through rotational (radio) and vibrational (infrared) spectroscopy agree in some comets - in others the infrared rate exceeds the radio rate substantially. b. With its strong dipole moment and H-bonding character, HCN should be linked more strongly in the nuclear ice to other molecules with similar properties (H2O, CH3OH), but instead its spatial release in some comets seems strongly coupled to volatiles that lack a dipole moment and thus do not form H-bonds (methane, ethane). c. The nucleus-centered rotational temperatures measured for H2O and other species (C2H6, CH3OH) usually agree within error, but those for HCN are often slightly smaller. d. In comet ISON, ALMA maps of HCN and the dust continuum show a slight displacement 80 km) in the centroids. We will

HCN Polymers: Toward Structure Comprehension Using High Resolution Mass Spectrometry

Science.gov (United States)

Bonnet, Jean-Yves; Thissen, Roland; Frisari, Ma; Vuitton, Veronique; Quirico, Eric; Le Roy, Léna; Fray, Nicolas; Cottin, Hervé; Horst, Sarah; Yelle, Roger

A lot of solar system materials, including cometary ices and Titan aerosols, contain dark matter that can be interpreted as complex nitrogen bearing organic matter [1]. In laboratory experi-ments, HCN polymers are thus analogs of great interest. In fact they may be present in Titan atmosphere and in comet nuclei and then reprocessed as a CN distributed source [2], when ices began to sublimate and ejects from the nucleus organic matter grains [3]. The presence of HCN polymers is suggested because HCN molecule has been directly observed in 1P/Halley comet [4] and others. HCN polymers are also of prebiotic interest [5] as it can form amino acid under hydrolysis conditions. Even if they have been studied during the last decades, their chemical composition and structure are still poorly understood, and a great analytical effort has to be continued. In this way we present a high resolution mass spectrometry (HRMS) and a high resolution tandem mass spectrometry (MS/HRMS) analysis of HCN polymers. It was shown [6] that this is a suitable technique to elucidate composition and structure of the soluble part of tholins analogs of Titan's atmosphere aerosols. HCN polymers have never been studied by HRMS, thus we used a LTQ-Orbitrap XL high resolution mass spectrometer to analyse the HCN polymers. These are produced at LISA by direct polymerisation of pure liquid HCN, catalyzed by ammonia. HCN polymers have been completely dissolved in methanol and then injected in the mass spectrometer by ElectroSpray Ionization (ESI). This atmospheric pressure ionization process produces protonated or deprotonated ions, but it does not fragment molecules. Thus HRMS, allows a direct access to the stoechiometry of all the ionizable molecules present in the samples. Fragmentation analyses (MS/MS) of selected ions have also been performed. Thess analysis provide information about the different chemical fonctionnalities present in HCN poly-mers and also about their structure. Thus we are able to

In situ measurements of HCN and CH3CN over the Pacific Ocean: Sources, sinks, and budgets

Science.gov (United States)

Singh, H. B.; Salas, L.; Herlth, D.; Kolyer, R.; Czech, E.; Viezee, W.; Li, Q.; Jacob, D. J.; Blake, D.; Sachse, G.; Harward, C. N.; Fuelberg, H.; Kiley, C. M.; Zhao, Y.; Kondo, Y.

2003-10-01

We report the first in situ measurements of hydrogen cyanide (HCN) and methyl cyanide (CH3CN, acetonitrile) from the Pacific troposphere (0-12 km) obtained during the NASA Transport and Chemical Evolution over the Pacific (TRACE-P) airborne mission (February-April 2001). Mean HCN and CH3CN mixing ratios of 243 ± 118 (median 218) ppt and 149 ± 56 (median 138) ppt, respectively, were measured. These in situ observations correspond to a mean tropospheric HCN column of 4.2 × 1015 molecules cm-2 and a CH3CN column of 2.5 × 1015 molecules cm-2. This is in good agreement with the 0-12 km HCN column of 4.4 (±0.6) × 1015 molecules cm-2 derived from infrared solar spectroscopic observations over Japan. Mixing ratios of HCN and CH3CN were greatly enhanced in pollution outflow from Asia and were well correlated with each other as well as with known tracers of biomass combustion (e.g., CH3Cl, CO). Volumetric enhancement (or emission) ratios (ERs) relative to CO in free tropospheric plumes, likely originating from fires, were 0.34% for HCN and 0.17% for CH3CN. ERs with respect to CH3Cl and CO in selected biomass burning (BB) plumes in the free troposphere and in boundary layer pollution episodes are used to estimate a global BB source of 0.8 ± 0.4 Tg (N) yr-1 for HCN and 0.4 ± 0.1 Tg (N) yr-1 for CH3CN. In comparison, emissions from industry and fossil fuel combustion are quite small (atmospheric residence time of 5.0 months for HCN and 6.6 months for CH3CN is calculated. A global budget analysis shows that the sources and sinks of HCN and CH3CN are roughly in balance but large uncertainties remain in part due to a lack of observational data from the atmosphere and the oceans. Pathways leading to the oceanic (and soil) degradation of these cyanides are poorly known but are expected to be biological in nature.

Large-scale upper tropospheric pollution observed by MIPAS HCN and C2H6 global distributions

Science.gov (United States)

Glatthor, N.; von Clarmann, T.; Stiller, G. P.; Funke, B.; Koukouli, M. E.; Fischer, H.; Grabowski, U.; Höpfner, M.; Kellmann, S.; Linden, A.

2009-12-01

We present global upper tropospheric HCN and C2H6 amounts derived from MIPAS/ENVISAT limb emission spectra. HCN and C2H6 are retrieved in the spectral regions 715.5-782.7 cm-1 and 811.5-835.7 cm-1, respectively. The datasets consist of 54 days between September 2003 and March 2004. This period covers the peak and decline of the southern hemispheric biomass burning period and some months thereafter. HCN is a nearly unambiguous tracer of biomass burning with an assumed tropospheric lifetime of several months. Indeed, the most significant feature in the MIPAS HCN dataset is an upper tropospheric plume of enhanced values caused by southern hemispheric biomass burning, which in September and October 2003 extended from tropical South America over Africa, Australia to the Southern Pacific. The spatial extent of this plume agrees well with the MOPITT CO distribution of September 2003. Further there is good agreement with the shapes and mixing ratios of the southern hemispheric HCN and C2H6 fields measured by the ACE experiment between September and November 2005. The MIPAS HCN plume extended from the lowermost observation height of 8 km up to about 16 km altitude, with maximum values of 500-600 pptv in October 2003. It was still clearly visible in December 2003, but had strongly decreased by March 2004, confirming the assumed tropospheric lifetime. The main sources of C2H6 are production and transmission of fossil fuels, followed by biofuel use and biomass burning. The C2H6 distribution also clearly reflected the southern hemispheric biomass burning plume and its seasonal variation, with maximum amounts of 600-700 pptv. Generally there was good spatial overlap between the southern hemispheric distributions of both pollution tracers, except for the region between Peru and the mid-Pacific. Here C2H6was considerably enhanced, whereas the HCN amounts were low. Backward trajectory calculations suggested that industrial pollution was responsible for the elevated C2H6

Large-scale upper tropospheric pollution observed by MIPAS HCN and C2H6 global distributions

Directory of Open Access Journals (Sweden)

A. Linden

2009-12-01

Full Text Available We present global upper tropospheric HCN and C2H6 amounts derived from MIPAS/ENVISAT limb emission spectra. HCN and C2H6 are retrieved in the spectral regions 715.5–782.7 cm−1 and 811.5–835.7 cm−1, respectively. The datasets consist of 54 days between September 2003 and March 2004. This period covers the peak and decline of the southern hemispheric biomass burning period and some months thereafter. HCN is a nearly unambiguous tracer of biomass burning with an assumed tropospheric lifetime of several months. Indeed, the most significant feature in the MIPAS HCN dataset is an upper tropospheric plume of enhanced values caused by southern hemispheric biomass burning, which in September and October 2003 extended from tropical South America over Africa, Australia to the Southern Pacific. The spatial extent of this plume agrees well with the MOPITT CO distribution of September 2003. Further there is good agreement with the shapes and mixing ratios of the southern hemispheric HCN and C2H6 fields measured by the ACE experiment between September and November 2005. The MIPAS HCN plume extended from the lowermost observation height of 8 km up to about 16 km altitude, with maximum values of 500–600 pptv in October 2003. It was still clearly visible in December 2003, but had strongly decreased by March 2004, confirming the assumed tropospheric lifetime. The main sources of C2H6 are production and transmission of fossil fuels, followed by biofuel use and biomass burning. The C2H6 distribution also clearly reflected the southern hemispheric biomass burning plume and its seasonal variation, with maximum amounts of 600–700 pptv. Generally there was good spatial overlap between the southern hemispheric distributions of both pollution tracers, except for the region between Peru and the mid-Pacific. Here C2H6was considerably enhanced, whereas the HCN amounts were low. Backward trajectory calculations suggested that industrial pollution was responsible

Contribution of presynaptic HCN channels to excitatory inputs of spinal substantia gelatinosa neurons.

Science.gov (United States)

Peng, S-C; Wu, J; Zhang, D-Y; Jiang, C-Y; Xie, C-N; Liu, T

2017-09-01

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are pathological pain-associated voltage-gated ion channels. They are widely expressed in central nervous system including spinal lamina II (also named the substantia gelatinosa, SG). Here, we examined the distribution of HCN channels in glutamatergic synaptic terminals as well as their role in the modulation of synaptic transmission in SG neurons from SD rats and glutamic acid decarboxylase-67 (GAD67)-GFP mice. We found that the expression of the HCN channel isoforms was varied in SG. The HCN4 isoform showed the highest level of co-localization with VGLUT2 (23±3%). In 53% (n=21/40 neurons) of the SG neurons examined in SD rats, application of HCN channel blocker, ZD7288 (10μM), decreased the frequency of spontaneous (s) and miniature (m) excitatory postsynaptic currents (EPSCs) by 37±4% and 33±4%, respectively. Consistently, forskolin (FSK) (an activator of adenylate cyclase) significantly increased the frequency of mEPSCs by 225±34%, which could be partially inhibited by ZD7288. Interestingly, the effects of ZD7288 and FSK on sEPSC frequency were replicated in non-GFP-expressing neurons, but not in GFP-expressing GABAergic SG neurons, in GAD67-GFP transgenic C57/BL6 mice. In summary, our results represent a previously unknown cellular mechanism by which presynaptic HCN channels, especially HCN4, regulate the glutamate release from presynaptic terminals that target excitatory, but not inhibitory SG interneurons. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

ALMA INVESTIGATION OF VIBRATIONALLY EXCITED HCN/HCO{sup +}/HNC EMISSION LINES IN THE AGN-HOSTING ULTRALUMINOUS INFRARED GALAXY IRAS 20551−4250

Energy Technology Data Exchange (ETDEWEB)

Imanishi, Masatoshi [Subaru Telescope, 650 North A’ohoku Place, Hilo, HI 96720 (United States); Nakanishi, Kouichiro [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Izumi, Takuma, E-mail: masa.imanishi@nao.ac.jp [Institute of Astronomy, School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan)

2016-07-01

We present the results of ALMA Cycle 2 observations of the ultraluminous infrared galaxy IRAS 20551−4250 at HCN/HCO{sup +}/HNC J = 3–2 lines at both vibrational ground ( v = 0) and vibrationally excited ( v {sub 2} = 1) levels. This galaxy contains a luminous buried active galactic nucleus (AGN), in addition to starburst activity, and our ALMA Cycle 0 data revealed a tentatively detected vibrationally excited HCN v {sub 2} = 1f J = 4–3 emission line. In our ALMA Cycle 2 data, the HCN/HCO{sup +}/HNC J = 3–2 emission lines at v = 0 are clearly detected. The HCN and HNC v {sub 2} = 1f J = 3–2 emission lines are also detected, but the HCO{sup +} v {sub 2} = 1f J = 3–2 emission line is not. Given the high energy level of v {sub 2} = 1 and the resulting difficulty of collisional excitation, we compared these results with those of the calculation of infrared radiative pumping, using the available infrared 5–35 μ m spectrum. We found that all of the observational results were reproduced if the HCN abundance was significantly higher than that of HCO{sup +} and HNC. The flux ratio and excitation temperature between v {sub 2} = 1f and v = 0, after correction for possible line opacity, suggests that infrared radiative pumping affects rotational ( J -level) excitation at v = 0 at least for HCN and HNC. The HCN-to-HCO{sup +} v = 0 flux ratio is higher than those of starburst-dominated regions, and will increase even more when the derived high HCN opacity is corrected. The enhanced HCN-to-HCO{sup +} flux ratio in this AGN-hosting galaxy can be explained by the high HCN-to-HCO{sup +} abundance ratio and sufficient HCN excitation at up to J = 4, rather than the significantly higher efficiency of infrared radiative pumping for HCN than HCO{sup +}.

Simple Organics and Biomonomers Identified in HCN Polymers: An Overview

Directory of Open Access Journals (Sweden)

Susana Osuna-Esteban

2013-07-01

Full Text Available Hydrogen cyanide (HCN is a ubiquitous molecule in the Universe. It is a compound that is easily produced in significant yields in prebiotic simulation experiments using a reducing atmosphere. HCN can spontaneously polymerise under a wide set of experimental conditions. It has even been proposed that HCN polymers could be present in objects such as asteroids, moons, planets and, in particular, comets. Moreover, it has been suggested that these polymers could play an important role in the origin of life. In this review, the simple organics and biomonomers that have been detected in HCN polymers, the analytical techniques and procedures that have been used to detect and characterise these molecules and an exhaustive classification of the experimental/environmental conditions that favour the formation of HCN polymers are summarised. Nucleobases, amino acids, carboxylic acids, cofactor derivatives and other compounds have been identified in HCN polymers. The great molecular diversity found in HCN polymers encourages their placement at the central core of a plausible protobiological system.

Ab initio study of low-energy electrons interacting with HCN molecules

International Nuclear Information System (INIS)

Jain, A.; Norcross, D.W.

1984-01-01

Our earlier study of low-energy electron scattering with HCN molecules is further improved by treating exchange exactly (in a separable exchange approximation 2 ) in Σ, π and Δ symmetries: the 3.8 eV π resonance is shifted towards lower energy (2.56 eV, the experimental position is around 2.26 eV 3 ), while in Σ and the Δ symmetries the difference is within 15%. We also study possible negative ion states of HCN by calculating potential energy curves with respect to C-H and C-N stretches. For example, there is evidence of an avoiding crossing between a 1Σ + and a 2Σ + state (C-H stretch) of HCN -

RESOLVING THE BRIGHT HCN(1–0) EMISSION TOWARD THE SEYFERT 2 NUCLEUS OF M51: SHOCK ENHANCEMENT BY RADIO JETS AND WEAK MASING BY INFRARED PUMPING?

International Nuclear Information System (INIS)

Matsushita, Satoki; Trung, Dinh-V-; Boone, Frédéric; Krips, Melanie; Lim, Jeremy; Muller, Sebastien

2015-01-01

We present high angular resolution observations of the HCN(1-0) emission (at ∼1'' or ∼34 pc), together with CO J = 1-0, 2-1, and 3-2 observations, toward the Seyfert 2 nucleus of M51 (NGC 5194). The overall HCN(1-0) distribution and kinematics are very similar to that of the CO lines, which have been indicated as the jet-entrained molecular gas in our past observations. In addition, high HCN(1-0)/CO(1-0) brightness temperature ratio of about unity is observed along the jets, similar to that observed at the shocked molecular gas in our Galaxy. These results strongly indicate that both diffuse and dense gases are entrained by the jets and outflowing from the active galactic nucleus. The channel map of HCN(1-0) at the systemic velocity shows a strong emission right at the nucleus, where no obvious emission has been detected in the CO lines. The HCN(1-0)/CO(1-0) brightness temperature ratio at this region reaches >2, a value that cannot be explained considering standard physical/chemical conditions. Based on our calculations, we suggest infrared pumping and possibly weak HCN masing, but still requiring an enhanced HCN abundance for the cause of this high ratio. This suggests the presence of a compact dense obscuring molecular gas in front of the nucleus of M51, which remains unresolved at our ∼1'' (∼34 pc) resolution, and consistent with the Seyfert 2 classification picture

RESOLVING THE BRIGHT HCN(1–0) EMISSION TOWARD THE SEYFERT 2 NUCLEUS OF M51: SHOCK ENHANCEMENT BY RADIO JETS AND WEAK MASING BY INFRARED PUMPING?

Energy Technology Data Exchange (ETDEWEB)

Matsushita, Satoki [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China); Trung, Dinh-V- [Institute of Physics, Vietnamese Academy of Science and Technology, 10, Daotan, BaDinh, Hanoi (Viet Nam); Boone, Frédéric [Université de Toulouse, UPS-OMP, IRAP, F-31400 Toulouse (France); Krips, Melanie [Institute de Radio Astronomie Millimétrique, 300 Rue de la Piscine, F-38406 Saint Martin d' Hères (France); Lim, Jeremy [Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong); Muller, Sebastien [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, SE-43992 Onsala (Sweden)

2015-01-20

We present high angular resolution observations of the HCN(1-0) emission (at ∼1'' or ∼34 pc), together with CO J = 1-0, 2-1, and 3-2 observations, toward the Seyfert 2 nucleus of M51 (NGC 5194). The overall HCN(1-0) distribution and kinematics are very similar to that of the CO lines, which have been indicated as the jet-entrained molecular gas in our past observations. In addition, high HCN(1-0)/CO(1-0) brightness temperature ratio of about unity is observed along the jets, similar to that observed at the shocked molecular gas in our Galaxy. These results strongly indicate that both diffuse and dense gases are entrained by the jets and outflowing from the active galactic nucleus. The channel map of HCN(1-0) at the systemic velocity shows a strong emission right at the nucleus, where no obvious emission has been detected in the CO lines. The HCN(1-0)/CO(1-0) brightness temperature ratio at this region reaches >2, a value that cannot be explained considering standard physical/chemical conditions. Based on our calculations, we suggest infrared pumping and possibly weak HCN masing, but still requiring an enhanced HCN abundance for the cause of this high ratio. This suggests the presence of a compact dense obscuring molecular gas in front of the nucleus of M51, which remains unresolved at our ∼1'' (∼34 pc) resolution, and consistent with the Seyfert 2 classification picture.

Response of Si- and Al-doped graphenes toward HCN: A computational study

International Nuclear Information System (INIS)

Rastegar, Somayeh F.; Peyghan, Ali Ahmadi; Hadipour, Nasser L.

2013-01-01

Highlights: ► Sensitivity of Si- and Al-doped graphene (SiG and AlG) toward HCN is investigated. ► The electronic properties of AlG are significantly changed in the presence of HCN. ► It is established that AlG can be a good sensor for HCN molecule. - Abstract: Sensitivity of Si- and Al-doped graphenes (SiG and AlG) toward toxic HCN has been investigated using density functional theory (DFT) in terms of energetic, geometric and electronic properties. Optimized configurations corresponding to physisorption and, subsequently, chemisorption of HCN on each surface have been identified. It is found that HCN molecule can be adsorbed on impurity atoms with adsorption energies about −27.20 and −38.75 kcal/mol on the SiG and the AlG, respectively. By comparing to HCN adsorption on SiG, it can be inferred that molecular HCN adsorbed on AlG can induce significant change in AlG conductivity. On the basis of calculated changes in the HOMO/LUMO energy gap it is found that electronic properties of AlG are sensitive toward adsorption of HCN and the reverse is correct for SiG, suggesting that the AlG may be a promising sensor for HCN.

Coupling catalytic hydrolysis and oxidation on Mn/TiO2-Al2O3 for HCN removal

Science.gov (United States)

Wang, Langlang; Wang, Xueqian; Cheng, Jinhuan; Ning, Ping; Lin, Yilong

2018-05-01

The manganese-modified titania-alumina (Mn/TiO2-Al2O3) catalyst synthesized by sol-gol method was used to remove hydrogen cyanide (HCN) from simulated flue gas. Further, effects of the mass ratios of Ti/Al, Mn loading, calcination temperature, and relative humidity on HCN conversion efficiency and catalytic activity were systematically investigated. The results indicated that the Mn/TiO2-Al2O3 catalyst exhibited significantly enhanced HCN removal efficiency, and the maximum yield of N2 increased to 68.02% without the participation of water vapor. When water vapor was added into the flue gas, the yield of N2 decreased and the formation of NOx was also inhibited. The XRD and XPS results indicated that Mn was mainly present in the form of Mn2+, Mn3+, and Mn4+ on the surface of catalyst and chemisorbed oxygen played a major role in the HCN catalytic oxidation process. The results of DSC-TGA analysis and H2-TPR indicated that the catalyst also exhibited a good thermal and chemical stability. NH3-TPD and CO2-TPD indicated that the surface of the catalyst mainly contained acidic sites. During the reaction, part of NH3 was adsorbed by Brönsted and Lewis acid sites. NH3 adsorbed on Lewis acid sites participated in NH3-SCR, which reduced the amount of NOx produced and resulted in a high N2 yield.

Gain-of-function HCN2 variants in genetic epilepsy.

Science.gov (United States)

Li, Melody; Maljevic, Snezana; Phillips, A Marie; Petrovski, Slave; Hildebrand, Michael S; Burgess, Rosemary; Mount, Therese; Zara, Federico; Striano, Pasquale; Schubert, Julian; Thiele, Holger; Nürnberg, Peter; Wong, Michael; Weisenberg, Judith L; Thio, Liu Lin; Lerche, Holger; Scheffer, Ingrid E; Berkovic, Samuel F; Petrou, Steven; Reid, Christopher A

2018-02-01

Genetic generalized epilepsy (GGE) is a common epilepsy syndrome that encompasses seizure disorders characterized by spike-and-wave discharges (SWDs). Pacemaker hyperpolarization-activated cyclic nucleotide-gated channels (HCN) are considered integral to SWD genesis, making them an ideal gene candidate for GGE. We identified HCN2 missense variants from a large cohort of 585 GGE patients, recruited by the Epilepsy Phenome-Genome Project (EPGP), and performed functional analysis using two-electrode voltage clamp recordings from Xenopus oocytes. The p.S632W variant was identified in a patient with idiopathic photosensitive occipital epilepsy and segregated in the family. This variant was also independently identified in an unrelated patient with childhood absence seizures from a European cohort of 238 familial GGE cases. The p.V246M variant was identified in a patient with photo-sensitive GGE and his father diagnosed with juvenile myoclonic epilepsy. Functional studies revealed that both p.S632W and p.V246M had an identical functional impact including a depolarizing shift in the voltage dependence of activation that is consistent with a gain-of-function. In contrast, no biophysical changes resulted from the introduction of common population variants, p.E280K and p.A705T, and the p.R756C variant from EPGP that did not segregate with disease. Our data suggest that HCN2 variants can confer susceptibility to GGE via a gain-of-function mechanism. © 2017 Wiley Periodicals, Inc.

HCN4 ion channel function is required for early events that regulate anatomical left-right patterning in a nodal and lefty asymmetric gene expression-independent manner.

Science.gov (United States)

Pai, Vaibhav P; Willocq, Valerie; Pitcairn, Emily J; Lemire, Joan M; Paré, Jean-François; Shi, Nian-Qing; McLaughlin, Kelly A; Levin, Michael

2017-10-15

Laterality is a basic characteristic of all life forms, from single cell organisms to complex plants and animals. For many metazoans, consistent left-right asymmetric patterning is essential for the correct anatomy of internal organs, such as the heart, gut, and brain; disruption of left-right asymmetry patterning leads to an important class of birth defects in human patients. Laterality functions across multiple scales, where early embryonic, subcellular and chiral cytoskeletal events are coupled with asymmetric amplification mechanisms and gene regulatory networks leading to asymmetric physical forces that ultimately result in distinct left and right anatomical organ patterning. Recent studies have suggested the existence of multiple parallel pathways regulating organ asymmetry. Here, we show that an isoform of the hyperpolarization-activated cyclic nucleotide-gated (HCN) family of ion channels (hyperpolarization-activated cyclic nucleotide-gated channel 4, HCN4) is important for correct left-right patterning. HCN4 channels are present very early in Xenopus embryos. Blocking HCN channels ( I h currents) with pharmacological inhibitors leads to errors in organ situs. This effect is only seen when HCN4 channels are blocked early (pre-stage 10) and not by a later block (post-stage 10). Injections of HCN4-DN (dominant-negative) mRNA induce left-right defects only when injected in both blastomeres no later than the 2-cell stage. Analysis of key asymmetric genes' expression showed that the sidedness of Nodal , Lefty , and Pitx2 expression is largely unchanged by HCN4 blockade, despite the randomization of subsequent organ situs, although the area of Pitx2 expression was significantly reduced. Together these data identify a novel, developmental role for HCN4 channels and reveal a new Nodal-Lefty-Pitx2 asymmetric gene expression-independent mechanism upstream of organ positioning during embryonic left-right patterning. © 2017. Published by The Company of Biologists Ltd.

Airborne measurements of CO2, CH4 and HCN in boreal biomass burning plumes

Science.gov (United States)

O'Shea, Sebastian J.; Bauguitte, Stephane; Muller, Jennifer B. A.; Le Breton, Michael; Archibald, Alex; Gallagher, Martin W.; Allen, Grant; Percival, Carl J.

2013-04-01

Biomass burning plays an important role in the budgets of a variety of atmospheric trace gases and particles. For example, fires in boreal Russia have been linked with large growths in the global concentrations of trace gases such as CO2, CH4 and CO (Langenfelds et al., 2002; Simpson et al., 2006). High resolution airborne measurements of CO2, CH4 and HCN were made over Eastern Canada onboard the UK Atmospheric Research Aircraft FAAM BAe-146 from 12 July to 4 August 2011. These observations were made as part of the BORTAS project (Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites). Flights were aimed at transecting and sampling the outflow from the commonly occurring North American boreal forest fires during the summer months and to investigate and identify the chemical composition and evolution of these plumes. CO2 and CH4 dry air mole fractions were determined using an adapted system based on a Fast Greenhouse Gas Analyser (FGGA, Model RMT-200) from Los Gatos Research Inc, which uses the cavity enhanced absorption spectroscopy technique. In-flight calibrations revealed a mean accuracy of 0.57 ppmv and 2.31 ppbv for 1 Hz observations of CO2 and CH4, respectively, during the BORTAS project. During these flights a number of fresh and photochemically-aged plumes were identified using simultaneous HCN measurements. HCN is a distinctive and useful marker for forest fire emissions and it was detected using chemical ionisation mass spectrometry (CIMS). In the freshest plumes, strong relationships were found between CH4, CO2 and other tracers for biomass burning. From this we were able to estimate that 8.5 ± 0.9 g of CH4 and 1512 ± 185 g of CO2 were released into the atmosphere per kg of dry matter burnt. These emission factors are in good agreement with estimates from previous studies and can be used to calculate budgets for the region. However for aged plumes the correlations between CH4 and other

Characterization of a right atrial subsidiary pacemaker and acceleration of the pacing rate by HCN over-expression.

Science.gov (United States)

Morris, Gwilym M; D'Souza, Alicia; Dobrzynski, Halina; Lei, Ming; Choudhury, Moinuddin; Billeter, Rudi; Kryukova, Yelena; Robinson, Richard B; Kingston, Paul A; Boyett, Mark R

2013-10-01

Although the right atrium (RA contains subsidiary atrial pacemaker (SAP) tissue that can take over from the sinoatrial node (SAN) in sick sinus syndrome (SSS), SAP tissue is bradycardic. Little is known about SAP tissue and one aim of the study was to characterize ion channel expression to obtain insight into SAP pacemaker mechanisms. A second aim was to determine whether HCN over-expression (a 'biopacemaker'-like strategy) can accelerate the pacemaker rate producing a pacemaker that is similar in nature to the SAN. SAP tissue was isolated from the rat and the leading pacemaker site was characterized. Cell size at the leading pacemaker site in the SAP was smaller than in the RA and comparable to that in the SAN. mRNA levels showed the SAP to be similar to, but distinct from, the SAN. For example, in the SAN and SAP, expression of Tbx3 and HCN1 was higher and Nav1.5 and Cx43 lower than in the RA. Organ-cultured SAP tissue beat spontaneously, but at a slower rate than the SAN. Adenovirus-mediated gene transfer of HCN2 and the chimeric protein HCN212 significantly increased the pacemaker rate of the SAP close to that of the native SAN, but HCN4 was ineffective. SAP tissue near the inferior vena cava is bradycardic, but shares characteristics with the SAN. Pacing can be accelerated by the over-expression of HCN2 or HCN212. This provides proof of concept for the use of SAP tissue as a substrate for biopacemaking in the treatment of SSS.

Searching for Faint Traces of CO(2-1) and HCN(4-3) Gas In Debris Disks

Science.gov (United States)

Stafford Lambros, Zachary; Hughes, A. Meredith

2018-01-01

The surprising presence of molecular gas in the debris disks around main sequence stars provides an opportunity to study the dissipation of primordial gas and, potentially, the composition of gas in other solar systems. Molecular gas is not expected to survive beyond the pre-main sequence phase, and it is not yet clear whether the gas is a remnant of the primordial protoplanetary material or whether the gas, like the dust, is second-generation material produced by collisional or photodesorption from planetesimals, exocomets, or the icy mantles of dust grains. Here we present two related efforts to characterize the prevalence and properties of gas in debris disks. First, we place the lowest limits to date on the CO emission from an M star debris disk, using 0.3" resolution observations of CO(2-1) emission from the AU Mic system with the Atacama Large Millimeter/submillimeter Array (ALMA). We place a 3-sigma upper limit on the integrated flux of 0.39 Jy km/s, corresponding to a maximum CO mass of 5e10-6 (Earth Masses) if the gas is in LTE. We also present the results of an ALMA search for HCN(4-3) emission from the prototypical gas-rich debris disk around 49 Ceti at a spatial resolution of 0.3". Despite hosting one of the brightest CO-rich debris disks yet discovered, our observations of 49 Ceti also yield a low upper limit of 0.057 Jy km/s in the HCN line, leaving CO as the only molecule clearly detected in emission from a debris disk. We employ several methods of detecting faint line emission from debris disks, including a model based on Keplerian kinematics as well as a spectral shifting method previously used to detect faint CO emission from the Fomalhaut debris disk, and compare our results.

HCN Production via Impact Ejecta Reentry During the Late Heavy Bombardment

Science.gov (United States)

Parkos, Devon; Pikus, Aaron; Alexeenko, Alina; Melosh, H. Jay

2018-04-01

Major impact events have shaped the Earth as we know it. The Late Heavy Bombardment is of particular interest because it immediately precedes the first evidence of life. The reentry of impact ejecta creates numerous chemical by-products, including biotic precursors such as HCN. This work examines the production of HCN during the Late Heavy Bombardment in more detail. We stochastically simulate the range of impacts on the early Earth and use models developed from existing studies to predict the corresponding ejecta properties. Using multiphase flow methods and finite-rate equilibrium chemistry, we then find the HCN production due to the resulting atmospheric heating. We use Direct Simulation Monte Carlo to develop a correction factor to account for increased yields due to thermochemical nonequilibrium. We then model 1-D atmospheric turbulent diffusion to find the time accurate transport of HCN to lower altitudes and ultimately surface water. Existing works estimate the necessary HCN molarity threshold to promote polymerization that is 0.01 M. For a mixing depth of 100 m, we find that the Late Heavy Bombardment will produce at least one impact event above this threshold with probability 24.1% for an oxidized atmosphere and 56.3% for a partially reduced atmosphere. For a mixing depth of 10 m, the probability is 79.5% for an oxidized atmosphere and 96.9% for a partially reduced atmosphere. Therefore, Late Heavy Bombardment impact ejecta is likely an HCN source sufficient for polymerization in shallow bodies of water, particularly if the atmosphere were in a partially reduced state.

The correlation between HCN/H2O flux ratios and disk mass: evidence for protoplanet formation

Science.gov (United States)

Rose, Caitlin; Salyk, Colette

2017-01-01

We analyze hydrogen cyanide (HCN) and water vapor flux ratios in protoplanetary disks as a way to trace planet formation. Analyzing only disks in the Taurus molecular cloud, Najita et al. (2013) found a tentative correlation between protoplanetary disk mass and the HCN/H2O line flux ratio in Spitzer-IRS emission spectra. They interpret this correlation to be a consequence of more massive disks forming planetesimals more efficiently than smaller disks, as the formation of large planetesimals may lock up water ice in the cool outer disk region and prevent it from migrating, drying out the inner disk. The sequestering of water (and therefore oxygen) in the outer disk may also increase the carbon-to- oxygen ratio in the inner disk, leading to enhanced organic molecule (e.g. HCN) emission. To confirm this trend, we expand the Najita et al. sample by calculating HCN/H2O line flux ratios for 8 more sources with known disk masses from clusters besides Taurus. We find agreement with the Najita et al. trend, suggesting that this is a widespread phenomenon. In addition, we find HCN/H2O line flux ratios for 17 more sources that await disk mass measurements, which should become commonplace in the ALMA era. Finally, we investigate linear fits and outliers to this trend, and discuss possible causes.

MLS/Aura L2 Hydrogen Cyanide (HCN) Mixing Ratio V003

Data.gov (United States)

National Aeronautics and Space Administration — ML2HCN is the EOS Aura Microwave Limb Sounder (MLS) standard product for hydrogen cyanide derived from radiances measured primarily by the 190 GHz radiometer. The...

MLS/Aura L2 Hydrogen Cyanide (HCN) Mixing Ratio V002

Data.gov (United States)

National Aeronautics and Space Administration — ML2HCN is the EOS Aura Microwave Limb Sounder (MLS) standard product for hydrogen cyanide derived from radiances measured primarily by the 190 GHz radiometer. The...

Genetically engineered cardiac pacemaker: Stem cells transfected with HCN2 gene and myocytes—A model

Science.gov (United States)

Kanani, S.; Pumir, A.; Krinsky, V.

2008-01-01

One of the successfully tested methods to design genetically engineered cardiac pacemaker cells consists in transfecting a human mesenchymal stem cell (hMSC) with a HCN2 gene and connecting it to a myocyte. We develop and study a mathematical model, describing a myocyte connected to a hMSC transfected with a HCN2 gene. The cardiac action potential is described both with the simple Beeler Reuter model, as well as with the elaborate dynamic Luo Rudy model. The HCN2 channel is described by fitting electrophysiological records, in the spirit of Hodgkin Huxley. The model shows that oscillations can occur in a pair myocyte-stem cell, that was not observed in the experiments yet. The model predicted that: (1) HCN pacemaker channels can induce oscillations only if the number of expressed I channels is low enough. At too high an expression level of I channels, oscillations cannot be induced, no matter how many pacemaker channels are expressed. (2) At low expression levels of I channels, a large domain of values in the parameter space (n, N) exists, where oscillations should be observed. We denote N the number of expressed pacemaker channels in the stem cell, and n the number of gap junction channels coupling the stem cell and the myocyte. (3) The expression levels of I channels observed in ventricular myocytes, both in the Beeler Reuter and in the dynamic Luo Rudy models are too high to allow to observe oscillations. With expression levels below ˜1/4 of the original value, oscillations can be observed. The main consequence of this work is that in order to obtain oscillations in an experiment with a myocyte-stem cell pair, increasing the values of n, N is unlikely to be helpful, unless the expression level of I has been reduced enough. The model also allows us to explore levels of gene expression not yet achieved in experiments, and could be useful to plan new experiments, aimed at improving the robustness of the oscillations.

THE HCN/HNC ABUNDANCE RATIO TOWARD DIFFERENT EVOLUTIONARY PHASES OF MASSIVE STAR FORMATION

Energy Technology Data Exchange (ETDEWEB)

Jin, Mihwa; Lee, Jeong-Eun [School of Space Research, Kyung Hee University, Yongin-Si, Gyeonggi-Do 446-701 (Korea, Republic of); Kim, Kee-Tae, E-mail: mihwajin.sf@gmail.com, E-mail: jeongeun.lee@khu.ac.kr, E-mail: ktkim@kasi.re.kr [Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 305-348 (Korea, Republic of)

2015-07-20

Using the H{sup 13}CN and HN{sup 13}C J = 1–0 line observations, the abundance ratio of HCN/HNC has been estimated for different evolutionary stages of massive star formation: infrared dark clouds (IRDCs), high-mass protostellar objects (HMPOs), and ultracompact H ii regions (UCH iis). IRDCs were divided into “quiescent IRDC cores (qIRDCc)” and “active IRDC cores (aIRDCc),” depending on star formation activity. The HCN/HNC ratio is known to be higher at active and high temperature regions related to ongoing star formation, compared to cold and quiescent regions. Our observations toward 8 qIRDCc, 16 aIRDCc, 23 HMPOs, and 31 UCH iis show consistent results; the ratio is 0.97 (±0.10), 2.65 (±0.88), 4.17 (±1.03), and 8.96 (±3.32) in these respective evolutionary stages, increasing from qIRDCc to UCH iis. The change of the HCN/HNC abundance ratio, therefore, seems directly associated with the evolutionary stages of star formation, which have different temperatures. One suggested explanation for this trend is the conversion of HNC to HCN, which occurs effectively at higher temperatures. To test the explanation, we performed a simple chemical model calculation. In order to fit the observed results, the energy barrier of the conversion must be much lower than the value provided by theoretical calculations.

Genetically engineered cardiac pacemaker: Stem cells transfected with HCN2 gene and myocytes-A model

Energy Technology Data Exchange (ETDEWEB)

Kanani, S. [Institut Genomique Fonctionelle, 141 Rue de la Cardonille, 34396 Montpellier (France); Institut Non Lineaire de Nice, CNRS and Universite de Nice, 1361 route des Lucioles, 06560 Valbonne (France); Pumir, A. [Institut Non Lineaire de Nice, CNRS and Universite de Nice, 1361 route des Lucioles, 06560 Valbonne (France); Laboratoire J.A. Dieudonne, CNRS and Universite de Nice, Parc Valrose, 06108 Nice (France)], E-mail: alain.pumir@unice.fr; Krinsky, V. [Institut Non Lineaire de Nice, CNRS and Universite de Nice, 1361 route des Lucioles, 06560 Valbonne (France)

2008-01-07

One of the successfully tested methods to design genetically engineered cardiac pacemaker cells consists in transfecting a human mesenchymal stem cell (hMSC) with a HCN2 gene and connecting it to a myocyte. We develop and study a mathematical model, describing a myocyte connected to a hMSC transfected with a HCN2 gene. The cardiac action potential is described both with the simple Beeler-Reuter model, as well as with the elaborate dynamic Luo-Rudy model. The HCN2 channel is described by fitting electrophysiological records, in the spirit of Hodgkin-Huxley. The model shows that oscillations can occur in a pair myocyte-stem cell, that was not observed in the experiments yet. The model predicted that: (1) HCN pacemaker channels can induce oscillations only if the number of expressed I{sub K1} channels is low enough. At too high an expression level of I{sub K1} channels, oscillations cannot be induced, no matter how many pacemaker channels are expressed. (2) At low expression levels of I{sub K1} channels, a large domain of values in the parameter space (n, N) exists, where oscillations should be observed. We denote N the number of expressed pacemaker channels in the stem cell, and n the number of gap junction channels coupling the stem cell and the myocyte. (3) The expression levels of I{sub K1} channels observed in ventricular myocytes, both in the Beeler-Reuter and in the dynamic Luo-Rudy models are too high to allow to observe oscillations. With expression levels below {approx}1/4 of the original value, oscillations can be observed. The main consequence of this work is that in order to obtain oscillations in an experiment with a myocyte-stem cell pair, increasing the values of n, N is unlikely to be helpful, unless the expression level of I{sub K1} has been reduced enough. The model also allows us to explore levels of gene expression not yet achieved in experiments, and could be useful to plan new experiments, aimed at improving the robustness of the oscillations.

Development of a high power HCN waveguide laser for plasma diagnostic

International Nuclear Information System (INIS)

Deng Zhongchao; Zhou Yan; Tang Yiwu; Yi Jiang; Gao Bingyi; Tian Chongli

2007-06-01

Both design and development of a high power cw HCN waveguide laser is described for multichannel FIR laser interferometer on the HL-2A divertor tokamak. The geometry parameters of stracture of the HCN laser are calculated according to scaling laws for cw 337 μm HCN waveguide laser offered by P. Belland et al. The designed value of output power of the laser that is more than 400 mW with discharge length of 5.6 m and 6.3 cm inner diameter of tube have been chosen in case of external loss of the cavity of 2%. At the same time, in order to get a laser system of stable output both of configuration and operating condition is discussed. In developed laser a hot LaB 6 cathode is employed to en- sure a stable discharge, the cavity mirrors are spaced using four invar rod of φ25 mm in diameter and an structure of adjusting machine for axially movable flat mirror in cavity has been also designed, and that it can be taken down many times without badly destroying alignment of the cavity etc.. A suit of pipes sys- tem of cw HCN laser is schemed out so that some experiments of operating parameter optimization can be done. The results of primary test of operating waveguide HCN laser are briefly showed. (authors)

PENGARUH LAMA PERENDAMAN KORO BENGU (Mucuna pruriens DALAM AIR KAPUR (Ca(OH2 TERHADAP KADAR ASAM SIANIDA (HCN

Directory of Open Access Journals (Sweden)

Arif Nurmawan Toro

2014-03-01

Full Text Available Latar belakang: Masyarakat Indonesia masih menitikberatkan pada komoditas kacang kedelai sebagai sumber utama protein, sedangkan pemanfaatan komoditas lain seperti koro benguk masih sangat minim. Minimnya pemanfaatan koro benguk ini karena di dalamnya terkandung senyawa alami berupa glokusida sianogenik yang dapat mengalami hidrolisis enzimatis menjadi asam sianida (HCN yang bersifat racun. Karena asam sianida bersifat asam yang sangat mudah larut dalam air, maka dilakukan perendaman menggunakan air kapur (Ca(OH2 bersifat basa yang dirasa cukup efektif menetralkan HCN dalam koro benguk.   Tujuan Penelitian: Mengetahui pengaruh lama perendaman koro benguk dalam air kapur terhadap kadar asam sianida dan mengetahui apakah air kapur lebih efektif dibandingkan air biasa dalam menetralkan HCN koro benguk.   Metode Penelitian: Penelitian dengan desain post test with control group. Obyek penelitian ini adalah koro benguk varietas benguk putih berumur 4-6 bulan yang diperoleh di Dusun Nogosari, Desa Purwosari, Kecamatan Girimulyo, Kabupaten Kulon Progo, DIY yang dilakukan perendaman dalam air sebagai kelompok kontrol dan air kapur 100 mg/L sebagai kelompok perlakuan selama 12, 24 dan 36 jam kemudian dilakukan destilasi. Destilat direaksikan dengan asam pikrat 1% kemudia diukur kadar HCN secara spektrofotometri.   Hasil: Kadar HCN  koro benguk pada perendaman dalam air selama 12 jam adalah 20,736 mg/kg, selama 24 jam adalah 19,348 mg/kg dan selama 36 jam adalah 16,786 mg/kg. Sedangkan kadar HCN pada perendaman air kapur 100 mg/L selama 12 jam adalah 19,020 mg/kg, selama 24 jam adalah 1,635 mg/kg dan selama 36 jam adalah 9,307 mg/kg. Hasil Uji ANOVA satu jalan pada kelompok perlakuan didapatkan nilai signifikansi 0.000 (p< 0.05.   Kesimpulan: Ada pengaruh bermakna lama perendaman koro benguk dalam air kapur terhadap kadar asam sianida. Perendaman dalam air kapur terbukti lebih efektif menetralkan asam sianida koro benguk dibandingkan perendaman dalam

A TENTATIVE IDENTIFICATION OF HCN ICE ON TRITON

International Nuclear Information System (INIS)

Burgdorf, M.; Cruikshank, D. P.; Dalle Ore, C. M.; Sekiguchi, T.; Nakamura, R.; Orton, G.; Quirico, E.; Schmitt, B.

2010-01-01

Spectra of Triton between 1.8 and 5.5 μm, obtained in 2007 May and 2009 November, have been analyzed to determine the global surface composition. The spectra were acquired with the grism and the prism of the Infrared Camera on board AKARI with spectral resolutions of 135 and 22, respectively. The data from 4 to 5 μm are shown in this Letter and compared to the spectra of N 2 , CO, and CO 2 , i.e., all the known ices on this moon that have distinct bands in this previously unexplored wavelength range. We report the detection of a 4σ absorption band at 4.76 μm (2101 cm -1 ), which we attribute tentatively to the presence of solid HCN. This is the sixth ice to be identified on Triton and an expected component of its surface because it is a precipitating photochemical product of Triton's thin N 2 and CH 4 atmosphere. It is also formed directly by irradiation of mixtures of N 2 and CH 4 ices. Here we consider only pure HCN, although it might be dissolved in N 2 on the surface of Triton because of the evaporation and recondensation of N 2 over its seasonal cycle. The AKARI spectrum of Triton also covers the wavelengths of the fundamental (1-0) band of β-phase N 2 ice (4.296 μm, 2328 cm -1 ), which has never been detected in an astronomical body before, and whose presence is consistent with the overtone (2-0) band previously reported. Fundamental bands of CO and CO 2 ices are also present.

THE NITROGEN ISOTOPIC COMPOSITION OF METEORITIC HCN

Energy Technology Data Exchange (ETDEWEB)

Pizzarello, Sandra, E-mail: pizzar@asu.edu [Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85018-1604 (United States)

2014-12-01

HCN is ubiquitous in extraterrestrial environments and is central to current theories on the origin of early solar system organic compounds such as amino acids. These compounds, observed in carbonaceous meteorites, were likely important in the origin and/or evolution of early life. As part of our attempts to understand the origin(s) of meteoritic CN{sup –}, we have analyzed the {sup 15}N/{sup 14}N isotopic composition of HCN gas released from water extracts of the Murchison meteorite and found its value to be near those of the terrestrial atmosphere. The findings, when evaluated viz-a-viz molecular abundances and isotopic data of meteoritic organic compounds, suggest that HCN formation could have occurred during the protracted water alteration processes known to have affected the mineralogy of many asteroidal bodies during their solar residence. This was an active synthetic stage, which likely involved simple gasses, organic molecules, their presolar precursors, as well as mineral catalysts and would have lead to the formation of molecules of differing isotopic composition, including some with solar values.

HCN Producing Bacteria Enable Sensing Of Non-Bioavailable Hg Species by the Whole Cell Biosensor

Science.gov (United States)

Horvat, M.; Rijavec, T.; Koron, N.; Lapanje, A.

2015-12-01

Bacteria play an important role in Hg transformation reactions. The production of cyanide (HCN) and other secondary metabolites seems to be key elements involved in these transformations. Current hypotheses link the role of HCN production to growth inhibition of nonHCN producing competitor organisms (role of an antimicrobial agent). Our past investigations showed that HCN production did not correlate with antimicrobial activity and since pK value of HCN is very high (pK = 9,21), it can be expected that most of the produced HCN is removed from the microenvironment. This way, the expected inhibitory concentrations can hardly be reached. Accordingly, we proposed a new concept, where the ability of complexation of transient metals by HCN served as a regulation process for the accessibility of micro-elements. In our study, we focused on the presence of HCN producing bacteria and carried it out in the Hg contaminated environment connected to the Idrija Mercury Mine, Slovenia. We characterised the isolates according to the presence of Hg resistance (HgR), level of HCN production and genetic similarities. In laboratory setups, using our merR whole cell based biosensor, we determined the transformation of low bioavailable Hg0 and HgS forms into bioavailable Hg by these HCN producing bacteria. We observed that HgR strains producing HCN had the highest impact on increased Hg bioavailability. In the proposed ecological strategy HgR HCN producing bacteria increase their competitive edge over non-HgR competitors through the increase of Hg toxicity. Due to their activity, Hg is made available to other organisms as well and thus enters into the ecosystem. Finally, using some of the characteristics of bacteria (e.g. Hg resistance genetic elements), we developed a fully automated sensing approach, combining biosensorics and mechatronics, to measure the bioavailability of Hg in situ.

Experimental conditions affecting the kinetics of aqueous HCN polymerization as revealed by UV-vis spectroscopy.

Science.gov (United States)

Marín-Yaseli, Margarita R; Moreno, Miguel; de la Fuente, José L; Briones, Carlos; Ruiz-Bermejo, Marta

2018-02-15

HCN polymerization is one of the most important and fascinating reactions in prebiotic chemistry, and interest in HCN polymers in the field of materials science is growing. However, little is known about the kinetics of the HCN polymerization process. In the present study, a first approach to the kinetics of two sets of aqueous HCN polymerizations, from NH 4 CN and NaCN, at middle temperatures between 4 and 38°C, has been carried out. For each series, the presence of air and salts in the reaction medium has been systematically explored. A previous kinetic analysis was conducted during the conversion of the insoluble black HCN polymers obtained as gel fractions in these precipitation polymerizations for a reaction of one month, where a limit conversion was achieved at the highest polymerization temperature. The kinetic description of the gravimetric data for this complex system shows a clear change in the linear dependence with the polymerization temperature for the reaction from NH 4 CN, besides a relevant catalytic effect of ammonium, in comparison with those data obtained from the NaCN series. These results also demonstrated the notable influence of air, oxygen, and the saline medium in HCN polymer formation. Similar conclusions were reached when the sol fractions were monitored by UV-vis spectroscopy, and a Hill type correlation was used to describe the polymerization profiles obtained. This technique was chosen because it provides an easy, prompt and fast method to follow the evolution of the liquid or continuous phase of the process under study. Copyright © 2017 Elsevier B.V. All rights reserved.

Structural Insight into the Gene Expression Profiling of the hcn Operon in Pseudomonas aeruginosa.

Science.gov (United States)

Chowdhury, Nilkanta; Bagchi, Angshuman

2017-07-01

Pseudomonas aeruginosa is a common opportunistic human pathogen. It generally attacks immunosuppressed patients like AIDS, cancer, cystic fibrosis, etc. The virulence of P. aeruginosa is mediated by various virulence factors. One of such potential virulence factors is HCN synthesized by HCN synthase enzyme, which is encoded by the hcnABC operon. The expressions of the genes of this operon are regulated by three transcriptional regulators, viz., LasR, ANR, and RhlR. In our previous work, we analyzed the molecular details of the functionalities of LasR. In this work, we focused on ANR. ANR is a regulatory protein which belongs to the FNR family and works in anaerobic condition. ANR binds to the promoter DNA, named ANR box, as a dimer. The dimerization of this ANR protein is regulated by Fe 4 S 4 , an iron-sulfur cluster. This dimer of ANR (ANR-Fe 4 S 4 /ANR-Fe 4 S 4 ) recognizes and binds the promoter DNA sequence and regulates the transcription of this hcnABC operon. Till date, the biomolecular details of the interactions of ANR dimer with the promoter DNA are not fully understood. Thus, we built the molecular model of ANR-Fe 4 S 4 /ANR-Fe 4 S 4 . We docked the complex with the corresponding promoter DNA region. We analyzed the mode of interactions with the promoter DNA under different conditions. Thus, we tried to analyze the functionality of the ANR protein during the expressions of the genes of the hcnABC operon. So far, this is the first report to detail the molecular mechanism of the gene expression in P. aeruginosa.

A search for the millimetre lines of HCN in Comets Wilson 1987 VII and Machholz 1988 XV

Science.gov (United States)

Crouvisier, J.; Despois, D.; Bockelee-Morvan, D.; Gerard, E.; Paubert, G.; Johansson, L. E. B.; Ekelund, L.; Winnberg, A.; Ge, W.; Irvine, W. M.; Kinzel, W. M.; Schloerb, F. P.

1990-08-01

The J(1-0) lines of HCN at 89 GHz were searched for in Comet Wilson 1987 VII, with the FCRAO, the SEST and the IRAM radio telescopes between February and June 1987. There was no firm detection, but significant upper limits were obtained, which put severe constraints on the HCN production rate in that comet. A direct comparison with the observations of P/Halley suggests that the HCN abundance relative to water might be smaller in Comet Wilson by at least a factor of two. The J(1-0) and J(3-2) lines of HCN at 89 and 266 GHz were searched for in Comet Machholz 1988 XV when it was close to perihelion at 0.17 AU from the sun. There was no detection. At that moment, the comet was probably no longer active.

EXTENDED HCN AND HCO{sup +} EMISSION IN THE STARBURST GALAXY M82

Energy Technology Data Exchange (ETDEWEB)

Salas, P.; Galaz, G. [Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicua Mackenna 4860, 782-0436 Macul, Santiago (Chile); Salter, D.; Herrera-Camus, R.; Bolatto, A. D. [Department of Astronomy and Laboratory for Millimeter-Wave Astronomy, University of Maryland, College Park, MD 20742 (United States); Kepley, A. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States)

2014-12-20

We mapped 3 mm continuum and line emission from the starburst galaxy M82 using the Combined Array for Research in Millimeter-wave Astronomy. We targeted the HCN, HCO{sup +}, HNC, CS, and HC{sub 3}N lines, but here we focus on the HCN and HCO{sup +} emission. The map covers a field of 1.'2 with an ≈5'' resolution. The HCN and HCO{sup +} observations are short spacings corrected. The molecular gas in M82 had been previously found to be distributed in a molecular disk, coincident with the central starburst, and a galactic scale outflow which originates in the central starburst. With the new short spacings-corrected maps we derive some of the properties of the dense molecular gas in the base of the outflow. From the HCN and HCO{sup +} J = (1-0) line emission, and under the assumptions of the gas being optically thin and in local thermodynamic equilibrium, we place lower limits on the amount of dense molecular gas in the base of the outflow. The lower limits are 7 × 10{sup 6} M {sub ☉} and 21 × 10{sup 6} M {sub ☉}, or ≳ 2% of the total molecular mass in the outflow. The kinematics and spatial distribution of the dense gas outside the central starburst suggests that it is being expelled through chimneys. Assuming a constant outflow velocity, the derived outflow rate of dense molecular gas is ≥0.3 M {sub ☉} yr{sup –1}, which would lower the starburst lifetime by ≥5%. The energy required to expel this mass of dense gas is (1-10) × 10{sup 52} erg.

New CO and HCN sources associated with IRAS carbon stars

Science.gov (United States)

NGUYEN-Q-RIEU; Epchtein, N.; TRUONG-BACH; Cohen, M.

1987-01-01

Emission of CO and HCN was detected in 22 out of a sample of 53 IRAS sources classified as unidentified carbon-rich objects. The sample was selected according to the presence of the silicon carbide feature as revealed by low-resolution spectra. The molecular line widths indicate that the CO and HCN emission arises from the circumstellar envelopes of very highly evolved stars undergoing mass loss. The visible stars tend to be deficient in CO as compared with unidentified sources. Most the detected CO and HCN IRAS stars are distinct and thick-shelled objects, but their infrared and CO luminosities are similar to those of IRC + 102156 AFGL and IRC-CO evolved stars. The 12 micron flux seems to be a good indicator of the distance, hence a guide for molecular searches.

Adsorption of HCN molecules on Ni, Pd and Pt-doped (7, 0) boron nitride nanotube: a DFT study

Science.gov (United States)

Habibi-Yangjeh, Aziz; Basharnavaz, Hadi

2018-05-01

We studied affinity of pure and Ni, Pd and Pt-doped (7, 0) boron nitride nanotubes (BNNTs) to toxic HCN molecules using density functional theory calculations. The results indicated that the pure (7, 0) BNNTs can weakly adsorb HCN molecules with adsorption energy of -0.2474 eV. Upon adsorption of HCN molecules on this nanotube, the band gap energy was decreased from 3.320 to 2.960 eV. The more negative adsorption energy between these transition metal-doped (7, 0) BNNTs and HCN molecules indicated that doping of (7, 0) BNNTs with Ni, Pd and Pt elements can significantly improve the affinity of BNNTs toward this gas. Additionally, it was found that the interaction energy between HCN molecules and Pt-doped BNNTs is more negative than those of the Ni and Pd-doped BNNTs. These observations suggested that the Pt-doped (7, 0) BNNTs are strongly sensitive to HCN molecules and therefore it may be used in gas sensor devices for detecting this toxic gas.

Distribution and function of HCN channels in the apical dendritic tuft of neocortical pyramidal neurons.

Science.gov (United States)

Harnett, Mark T; Magee, Jeffrey C; Williams, Stephen R

2015-01-21

The apical tuft is the most remote area of the dendritic tree of neocortical pyramidal neurons. Despite its distal location, the apical dendritic tuft of layer 5 pyramidal neurons receives substantial excitatory synaptic drive and actively processes corticocortical input during behavior. The properties of the voltage-activated ion channels that regulate synaptic integration in tuft dendrites have, however, not been thoroughly investigated. Here, we use electrophysiological and optical approaches to examine the subcellular distribution and function of hyperpolarization-activated cyclic nucleotide-gated nonselective cation (HCN) channels in rat layer 5B pyramidal neurons. Outside-out patch recordings demonstrated that the amplitude and properties of ensemble HCN channel activity were uniform in patches excised from distal apical dendritic trunk and tuft sites. Simultaneous apical dendritic tuft and trunk whole-cell current-clamp recordings revealed that the pharmacological blockade of HCN channels decreased voltage compartmentalization and enhanced the generation and spread of apical dendritic tuft and trunk regenerative activity. Furthermore, multisite two-photon glutamate uncaging demonstrated that HCN channels control the amplitude and duration of synaptically evoked regenerative activity in the distal apical dendritic tuft. In contrast, at proximal apical dendritic trunk and somatic recording sites, the blockade of HCN channels decreased excitability. Dynamic-clamp experiments revealed that these compartment-specific actions of HCN channels were heavily influenced by the local and distributed impact of the high density of HCN channels in the distal apical dendritic arbor. The properties and subcellular distribution pattern of HCN channels are therefore tuned to regulate the interaction between integration compartments in layer 5B pyramidal neurons. Copyright © 2015 the authors 0270-6474/15/351024-14$15.00/0.

A widely tunable, near-infrared laser-based trace gas sensor for hydrogen cyanide (HCN) detection in exhaled breath

Science.gov (United States)

Azhar, M.; Mandon, J.; Neerincx, A. H.; Liu, Z.; Mink, J.; Merkus, P. J. F. M.; Cristescu, S. M.; Harren, F. J. M.

2017-11-01

A compact, cost-effective sensor is developed for detection of hydrogen cyanide (HCN) in exhaled breath within seconds. For this, an off-axis integrated cavity output spectroscopy setup is combined with a widely tunable compact near-infrared laser (tunability 1527-1564 nm). For HCN a detection sensitivity has been obtained of 8 ppbv in nitrogen (within 1 s), equal to a noise equivalent absorption sensitivity of 1.9 × 10-9 cm-1 Hz-1/2. With this sensor we demonstrated the presence of HCN in exhaled breath; its detection could be a good indicator for bacterial lung infection. Due to its compact, cost-effective and user-friendly design, this laser-based sensor has the potential to be implemented in future clinical applications.

Widespread HCN maser emission in carbon-rich evolved stars

Science.gov (United States)

Menten, K. M.; Wyrowski, F.; Keller, D.; Kamiński, T.

2018-05-01

Context. HCN is a major constituent of the circumstellar envelopes of carbon-rich evolved stars, and rotational lines from within its vibrationally excited states probe parts of these regions closest to the stellar surface. A number of such lines are known to show maser action. Historically, in one of them, the 177 GHz J = 2 → 1 line in the l-doubled bending mode has been found to show relatively strong maser action, with results only published for a single object, the archetypical high-mass loss asymptotic giant branch (AGB) star IRC+10216. Aims: To examine how common 177 GHz HCN maser emission is, we conducted an exploratory survey for this line toward a select sample of carbon-rich asymptotic giant branch stars that are observable from the southern hemisphere. Methods: We used the Atacama Pathfinder Experiment 12 meter submillimeter Telescope (APEX) equipped with a new receiver to simultaneously observe three J = 2 → 1 HCN rotational transitions, the (0, 11c, 0) and (0, 11d, 0) l-doublet components, and the line from the (0,0,0) ground state. Results: The (0, 11c, 0) maser line is detected toward 11 of 13 observed sources, which all show emission in the (0,0,0) transition. In most of the sources, the peak intensity of the (0, 11c, 0) line rivals that of the (0,0,0) line; in two sources, it is even stronger. Except for the object with the highest mass-loss rate, IRC+10216, the (0, 11c, 0) line covers a smaller velocity range than the (0,0,0) line. The (0, 11d, 0) line, which is detected in four of the sources, is much weaker than the other two lines and covers a velocity range that is smaller yet, again except for IRC+10216. Compared to its first detection in 1989, the profile of the (0, 11c, 0) line observed toward IRC+10216 looks very different, and we also appear to see variability in the (0,0,0) line profile (at a much lower degree). Our limited information on temporal variabilitydisfavors a strong correlation of maser and stellar continuum flux

Noise-induced plasticity of KCNQ2/3 and HCN channels underlies vulnerability and resilience to tinnitus

Science.gov (United States)

Li, Shuang; Kalappa, Bopanna I; Tzounopoulos, Thanos

2015-01-01

Vulnerability to noise-induced tinnitus is associated with increased spontaneous firing rate in dorsal cochlear nucleus principal neurons, fusiform cells. This hyperactivity is caused, at least in part, by decreased Kv7.2/3 (KCNQ2/3) potassium currents. However, the biophysical mechanisms underlying resilience to tinnitus, which is observed in noise-exposed mice that do not develop tinnitus (non-tinnitus mice), remain unknown. Our results show that noise exposure induces, on average, a reduction in KCNQ2/3 channel activity in fusiform cells in noise-exposed mice by 4 days after exposure. Tinnitus is developed in mice that do not compensate for this reduction within the next 3 days. Resilience to tinnitus is developed in mice that show a re-emergence of KCNQ2/3 channel activity and a reduction in HCN channel activity. Our results highlight KCNQ2/3 and HCN channels as potential targets for designing novel therapeutics that may promote resilience to tinnitus. DOI: http://dx.doi.org/10.7554/eLife.07242.001 PMID:26312501

Catalytic and Gas-Solid Reactions Involving HCN over Limestone

DEFF Research Database (Denmark)

Jensen, Anker; Johnsson, Jan Erik; Dam-Johansen, Kim

1997-01-01

In coal-fired combustion systems solid calcium species may be present as ash components or limestone added to the combustion chamber. In this study heterogeneous reactions involving HCN over seven different limestones were investigated in a laboratory fixed-bed quartz reactor at 873-1,173 K...

cAMP control of HCN2 channel Mg2+ block reveals loose coupling between the cyclic nucleotide-gating ring and the pore.

Directory of Open Access Journals (Sweden)

Alex K Lyashchenko

Full Text Available Hyperpolarization-activated cyclic nucleotide-regulated HCN channels underlie the Na+-K+ permeable IH pacemaker current. As with other voltage-gated members of the 6-transmembrane KV channel superfamily, opening of HCN channels involves dilation of a helical bundle formed by the intracellular ends of S6 albeit this is promoted by inward, not outward, displacement of S4. Direct agonist binding to a ring of cyclic nucleotide-binding sites, one of which lies immediately distal to each S6 helix, imparts cAMP sensitivity to HCN channel opening. At depolarized potentials, HCN channels are further modulated by intracellular Mg2+ which blocks the open channel pore and blunts the inhibitory effect of outward K+ flux. Here, we show that cAMP binding to the gating ring enhances not only channel opening but also the kinetics of Mg2+ block. A combination of experimental and simulation studies demonstrates that agonist acceleration of block is mediated via acceleration of the blocking reaction itself rather than as a secondary consequence of the cAMP enhancement of channel opening. These results suggest that the activation status of the gating ring and the open state of the pore are not coupled in an obligate manner (as required by the often invoked Monod-Wyman-Changeux allosteric model but couple more loosely (as envisioned in a modular model of protein activation. Importantly, the emergence of second messenger sensitivity of open channel rectification suggests that loose coupling may have an unexpected consequence: it may endow these erstwhile "slow" channels with an ability to exert voltage and ligand-modulated control over cellular excitability on the fastest of physiologically relevant time scales.

THE VARIABILITY OF HCN IN TITAN’S UPPER ATMOSPHERE AS IMPLIED BY THE CASSINI ION-NEUTRAL MASS SPECTROMETER MEASUREMENTS

Energy Technology Data Exchange (ETDEWEB)

Cui, J.; Cao, Y.-T. [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Lavvas, P. P. [Groupe de Spectroscopie Moleculaire et Atmospherique, Universite de Reims, Champagne-Ardenne, CNRS UMR F-7331 (France); Koskinen, T. T. [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States)

2016-07-20

HCN is an important constituent in Titan’s upper atmosphere, serving as the main coolant in the local energy budget. In this study, we derive the HCN abundance at the altitude range of 960–1400 km, combining the Ion-Neutral Mass Spectrometer data acquired during a large number of Cassini flybys with Titan. Typically, the HCN abundance declines modestly with increasing altitude and flattens to a near constant level above 1200 km. The data reveal a tendency for dayside depletion of HCN, which is clearly visible below 1000 km but weakens with increasing altitude. Despite the absence of convincing anti-correlation between HCN volume mixing ratio and neutral temperature, we argue that the variability in HCN abundance makes an important contribution to the large temperature variability observed in Titan’s upper atmosphere.

Lamellar γ-AlOOH architectures: Synthesis and application for the removal of HCN

International Nuclear Information System (INIS)

Hou Hongwei; Zhu You; Tang Gangling; Hu Qingyuan

2012-01-01

Using hexadecyl trimethyl ammonium bromide (CTAB) as a structure-directing agent and precipitator, the complete synthesis of lamellar γ-AlOOH architectures was successfully accomplished via a hydrothermal route. Different product structures were obtained by varying the molar ratio of aluminum nitrate and CTAB. Several techniques, including X-ray powder diffraction, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, and differential scanning calorimetry thermal analysis, were used to characterize the products. The effects of CTAB concentration, reaction temperature and time, and the molar ratio of Al 3+ /CTAB on the product morphologies were investigated. The nitrogen adsorption and desorption measurements indicated that the γ-AlOOH architectures possess a Brunauer–Emmett–Teller surface area of approximately 75.02 m 2 /g. It was also demonstrated that 10 mg γ-AlOOH architectures can remove 45.3% of the HCN (1.68 μg/mL) from model wastewater. When 0.03 mg/cig γ-AlOOH architectures were combined with cigarette paper, 8.12% of the present HCN was adsorbed. These results indicate that lamellar γ-AlOOH architectures may be a potential adsorbent for removing HCN from highly toxic pollutant solutions and harmful cigarette smoke. Highlights: ► Hexadecyl trimethyl ammonium bromide (CTAB) was used as a structure-directing agent and precipitator. ► Hydrothermal treatment enables growth of lamellar γ-AlOOH architectures. ► Lamellar γ-AlOOH architectures were demonstrated to exhibit high BET surface area and excellent adsorptive capacity. ► HCN in contaminated water and cigarette smoke can be effectively removed by the prepared lamellar γ-AlOOH superstructures.

HCN channels segregate stimulation‐evoked movement responses in neocortex and allow for coordinated forelimb movements in rodents

Science.gov (United States)

Farrell, Jordan S.; Palmer, Laura A.; Singleton, Anna C.; Pittman, Quentin J.; Teskey, G. Campbell

2016-01-01

Key points The present study tested whether HCN channels contribute to the organization of motor cortex and to skilled motor behaviour during a forelimb reaching task.Experimental reductions in HCN channel signalling increase the representation of complex multiple forelimb movements in motor cortex as assessed by intracortical microstimulation.Global HCN1KO mice exhibit reduced reaching accuracy and atypical movements during a single‐pellet reaching task relative to wild‐type controls.Acute pharmacological inhibition of HCN channels in forelimb motor cortex decreases reaching accuracy and increases atypical movements during forelimb reaching. Abstract The mechanisms by which distinct movements of a forelimb are generated from the same area of motor cortex have remained elusive. Here we examined a role for HCN channels, given their ability to alter synaptic integration, in the expression of forelimb movement responses during intracortical microstimulation (ICMS) and movements of the forelimb on a skilled reaching task. We used short‐duration high‐resolution ICMS to evoke forelimb movements following pharmacological (ZD7288), experimental (electrically induced cortical seizures) or genetic approaches that we confirmed with whole‐cell patch clamp to substantially reduce I h current. We observed significant increases in the number of multiple movement responses evoked at single sites in motor maps to all three experimental manipulations in rats or mice. Global HCN1 knockout mice were less successful and exhibited atypical movements on a skilled‐motor learning task relative to wild‐type controls. Furthermore, in reaching‐proficient rats, reaching accuracy was reduced and forelimb movements were altered during infusion of ZD7288 within motor cortex. Thus, HCN channels play a critical role in the separation of overlapping movement responses and allow for successful reaching behaviours. These data provide a novel mechanism for the encoding of multiple

Targeting miR-423-5p Reverses Exercise Training-Induced HCN4 Channel Remodeling and Sinus Bradycardia

DEFF Research Database (Denmark)

D'Souza, Alicia; Pearman, Charles M.; Wang, Yanwen

2017-01-01

-generation sequencing and quantitative real-time reverse transcription polymerase chain reaction showed remodeling of miRs in the sinus node of swim-trained mice. Computational predictions highlighted a prominent role for miR-423-5p. Interaction between miR-423-5p and HCN4 was confirmed by a dose-dependent reduction...

First-principles insights into interaction of CO, NO, and HCN with Ag{sub 8}

Energy Technology Data Exchange (ETDEWEB)

Torbatian, Zahra; Hashemifar, S. Javad, E-mail: hashemifar@cc.iut.ac.ir; Akbarzadeh, Hadi [Department of Physics, Isfahan University of Technology, 84156-83111 Isfahan (Iran, Islamic Republic of)

2014-02-28

We use static as well as time-dependent first-principles computations to study interaction of the CO, NO, and HCN molecules with the Ag{sub 8} nanocluster. The many-body based GW correction is applied for accurate description of the highest occupied (HOMO) and the lowest unoccupied (LUMO) molecular orbital levels. It is argued that the adsorption of these molecules changes the stable structure of Ag{sub 8} from Td to the more chemically active D{sub 2d} symmetry. We discuss that the CO, NO, and HCN molecules prefer to adsorb on the atom of the cluster with significant contribution to both HOMO and LUMO, for the accomplishment of the required charge transfers in the systems. The charge back donation is found to leave an excess energy of about 110 meV on the NO molecular bond, evidencing potential application of silver clusters for NO reduction. It is argued that CO and specially NO exhibit strong physical interaction with the silver cluster and hence significantly modify the electronic and optical properties of the system, while HCN makes very week physical bonds with the cluster. The optical absorption spectra of the Ag{sub 8} cluster before and after molecule adsorption are computed and a nontrivial red shift is observed in the NO and HCN adsorbed clusters.

Rate Coefficients for Reactions of Ethynyl Radical (C2H) With HCN and CH3CN: Implications for the Formation of Comples Nitriles on Titan

Science.gov (United States)

Hoobler, Ray J.; Leone, Stephen R.

1997-01-01

Rate coefficients for the reactions of C2H + HCN yields products and C2H + CH3CN yields products have been measured over the temperature range 262-360 K. These experiments represent an ongoing effort to accurately measure reaction rate coefficients of the ethynyl radical, C2H, relevant to planetary atmospheres such as those of Jupiter and Saturn and its satellite Titan. Laser photolysis of C2H2 is used to produce C2H, and transient infrared laser absorption is employed to measure the decay of C2H to obtain the subsequent reaction rates in a transverse flow cell. Rate constants for the reaction C2H + HCN yields products are found to increase significantly with increasing temperature and are measured to be (3.9-6.2) x 10(exp 13) cm(exp 3) molecules(exp -1) s(exp -1) over the temperature range of 297-360 K. The rate constants for the reaction C2H + CH3CN yields products are also found to increase substantially with increasing temperature and are measured to be (1.0-2.1) x 10(exp -12) cm(exp 3) molecules(exp -1) s(exp -1) over the temperature range of 262-360 K. For the reaction C2H + HCN yields products, ab initio calculations of transition state structures are used to infer that the major products form via an addition/elimination pathway. The measured rate constants for the reaction of C2H + HCN yields products are significantly smaller than values currently employed in photochemical models of Titan, which will affect the HC3N distribution.

Is Photolytic Production a Viable Source of HCN and HNC in Astrophysical Environments? A Laboratory-based Feasibility Study of Methyl Cyanoformate

Science.gov (United States)

Wilhelm, Michael J.; Martínez-Núñez, Emilio; González-Vázquez, Jesús; Vázquez, Saulo A.; Smith, Jonathan M.; Dai, Hai-Lung

2017-11-01

Motivated by the possibility that cyano-containing hydrocarbons may act as photolytic sources for HCN and HNC in astrophysical environments, we conducted a combined experimental and theoretical investigation of the 193 nm photolysis of the cyano-ester, methyl cyanoformate (MCF). Experimentally, nanosecond time-resolved infrared emission spectroscopy was used to detect the emission from nascent products generated in the photolysis reaction. The time-resolved spectra were analyzed using a recently developed spectral reconstruction analysis, which revealed spectral bands assignable to HCN and HNC. Fitting of the emission band shape and intensity allowed determination of the photolysis quantum yields of HCN, HNC, and {CN}({A}2{{{\\Pi }}}1) and an HNC/HCN ratio of ˜0.076 ± 0.059. Additionally, multiconfiguration self-consistent field calculations were used to characterize photoexcitation-induced reactions in the ground and four lowest singlet excited states of MCF. At 193 nm excitation, dissociation is predicted to occur predominantly on the repulsive S 2 state, with minor pathways via internal conversion from S 2 to highly excited ground state. An automated transition-state search algorithm was employed to identify the corresponding ground-state dissociation channels, and Rice-Ramsperger-Kassel-Marcus and Kinetic Monte Carlo simulations were used to calculate the associated branching ratios. The proposed mechanisms were validated using the experimentally measured and quasi-classical trajectory-deduced nascent internal energy distributions of HCN and HNC. This work, along with previous studies, illustrates the propensity for cyano-containing hydrocarbons to act as photolytic sources for astrophysical HCN and HNC and may help explain the observed overabundance of HNC in astrophysical environments.

First-principle study of structural, electronic, vibrational and magnetic properties of HCN adsorbed graphene doped with Cr, Mn and Fe

International Nuclear Information System (INIS)

Shi, Li Bin; Wang, Yong Ping; Dong, Hai Kuan

2015-01-01

Graphical abstract: - Highlights: • Cr, Mn and Fe doped graphene is more active to adsorb HCN molecule than pristine graphene. • The conductivity of Fe and Mn doped graphene hardly changes after adsorption HCN molecule. • The conductivity of Cr doped graphene can be affected significantly due to HCN adsorption. • The Cr, Mn and Fe may destroy the long range order in graphene. • Phonon density of states suggests that Cr doped graphene is stable. - Abstract: The adsorption energy, electronic structure, lattice vibration and magnetic properties of Cr, Mn and Fe doped graphene with and without HCN adsorption are investigated by the first principles based on density functional theory. The physisorption and chemisorption have been identified. In the paper, Cr-NG, Mn-NG and Fe-NG denote HCN adsorption on Cr, Mn and Fe doped graphene with N atom toward the adsorption site. It is found that the adsorption energy is −1.36 eV for Fe-NG, −0.60 eV for Mn-NG and −0.86 eV for Cr-NG. The Cr-NG will convert from half-metallic behavior to semiconductor after adsorbing HCN molecule, which indicates that the conductivity changes significantly. Phonon density of states (PDOS) shows that the long range order in graphene can be destroyed by doping Fe, Mn and Cr. The imaginary frequency mode in PDOS suggests that Fe and Mn doped graphene is unstable, while Cr doped graphene is stable. The electronic properties are sensitive toward adsorbing HCN, indicating that Cr doped graphene is a promising sensor for detecting HCN molecule. This study provides a useful basis for understanding of a wide variety of physical properties on graphene

DFT coupled with NEGF study of ultra-sensitive HCN and HNC gases detection and distinct I-V response based on phosphorene.

Science.gov (United States)

Pang, Jiu; Yang, Qun; Ma, Xiaosong; Wang, Liming; Tan, Chunjian; Xiong, Daxi; Ye, Huaiyu; Chen, Xianping

2017-11-22

The sensing performances of pristine and X-doped phosphorene substrates (X = Al, Si, and S atoms) toward the adsorption of the toxic gases HCN and HNC were systematically investigated by first-principles simulations. The numerical results show that the pristine phosphorene is sensitive to HCN and HNC molecules with moderate adsorption energy, excellent charge transfer, high sensitivity and selectivity, implying its potential applications as excellent HCN and HNC sensors. In addition, the Al-doped phosphorene exhibits extremely high reactive activity toward HCN and HNC gases; thus, it has potential for use as a metal-free catalyst for activating or catalyzing HCN or HNC adsorbates. Moreover, the transport properties, i.e., current-voltage (I-V) characteristics, were calculated by the non-equilibrium Green's function (NEGF) method within the framework of the density functional theory (DFT). The obtained results reveal that the adsorbed HCN or HNC gas molecules have a remarkable impact on the electronic conductivity of phosphorene, and the zigzag direction of phosphorene is more sensitive to gas molecules than the armchair direction. The combination of the high sensitivity, superior selectivity, and moderate adsorption energy of pristine phosphorene toward HCN or HNC gas molecules adsorption, makes phosphorene an excellent candidate for HCN and HNC sensors.

Photodissociation of HCN and HNC isomers in the 7-10 eV energy range

Energy Technology Data Exchange (ETDEWEB)

Chenel, Aurelie; Roncero, Octavio, E-mail: octavio.roncero@csic.es [Instituto de Física Fundamental (IFF-CSIC), C.S.I.C., Serrano 123, 28006 Madrid (Spain); Aguado, Alfredo [Departamento de Química Física Aplicada (UAM), Unidad Asociada a IFF-CSIC, Facultad de Ciencias Módulo 14, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Agúndez, Marcelino; Cernicharo, José [Instituto de Ciencia de Materiales de Madrid, CSIC, C/ Sor Juana Inés de la Cruz 3, 28049 Cantoblanco (Spain)

2016-04-14

The ultraviolet photoabsorption spectra of the HCN and HNC isomers have been simulated in the 7-10 eV photon energy range. For this purpose, the three-dimensional adiabatic potential energy surfaces of the 7 lowest electronic states, and the corresponding transition dipole moments, have been calculated, at multireference configuration interaction level. The spectra are calculated with a quantum wave packet method on these adiabatic potential energy surfaces. The spectra for the 3 lower excited states, the dissociative electronic states, correspond essentially to predissociation peaks, most of them through tunneling on the same adiabatic state. The 3 higher electronic states are bound, hereafter electronic bound states, and their spectra consist of delta lines, in the adiabatic approximation. The radiative lifetime towards the ground electronic states of these bound states has been calculated, being longer than 10 ns in all cases, much longer that the characteristic predissociation lifetimes. The spectra of HCN is compared with the available experimental and previous theoretical simulations, while in the case of HNC there are no previous studies to our knowledge. The spectrum for HNC is considerably more intense than that of HCN in the 7-10 eV photon energy range, which points to a higher photodissociation rate for HNC, compared to HCN, in astrophysical environments illuminated by ultraviolet radiation.

MEG3, HCN3 and linc01105 influence the proliferation and apoptosis of neuroblastoma cells via the HIF-1α and p53 pathways.

Science.gov (United States)

Tang, Weitao; Dong, Kuiran; Li, Kai; Dong, Rui; Zheng, Shan

2016-11-08

The purpose of this study was to investigate the differential expression and functional roles of long non-coding RNAs (lncRNAs) in neuroblastoma tissue. LncRNA microarrays were used to identify differentially expressed lncRNAs between tumor and para-tumor tissues. In total, in tumor tissues, 3,098 and 1,704 lncRNAs were upregulated and downregulated, respectively. HCN3 and linc01105 exhibited the higher expression (P INSS) stage were -0.48, -0.58 and -0.55, respectively. In conclusion, we have identified lncRNAs that are differentially expressed in neuroblastoma tissues. The lncRNAs HCN3, linc01105, and MEG3 may be important in biological behaviors of neuroblastoma through mechanisms involving p53 pathway members such as HIF-1α, Noxa, and Bid. The expressions of MEG3, HCN3 and linc01105 are all negatively correlated with the INSS stage.

ALMA IMAGING OF HCN, CS, AND DUST IN ARP 220 AND NGC 6240

Energy Technology Data Exchange (ETDEWEB)

Scoville, Nick; Manohar, Swarnima; Murchikova, Lena [California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Sheth, Kartik [North American ALMA Science Center, National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22901 (United States); Walter, Fabian; Zschaechner, Laura [Max-Planck-Institut fur Astronomie, Konigstuhl 17, D-69117 Heidelberg (Germany); Yun, Min [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Koda, Jin [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (United States); Sanders, David; Barnes, Joshua [Institute for Astronomy, 2680 Woodlawn Drive, University of Hawaii, Honolulu, Hawaii, HI 96822 (United States); Thompson, Todd [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Robertson, Brant; Tacconi, Linda; Narayanan, Desika [Department of Astronomy and Steward Observatory, University of Arizona, Tucson AZ 85721 (United States); Genzel, Reinhard; Davies, Richard [Max-Planck-Institut fur extraterrestrische Physik (MPE), Giessenbachstrasse, D-85748 Garching (Germany); Hernquist, Lars [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Brown, Robert [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22901 (United States); Hayward, Christopher C. [TAPIR 350-17, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Kartaltepe, Jeyhan [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); and others

2015-02-10

We report ALMA Band 7 (350 GHz) imaging at 0.''4-0.''6 resolution and Band 9 (696 GHz) at ∼0.''25 resolution of the luminous IR galaxies Arp 220 and NGC 6240. The long wavelength dust continuum is used to estimate interstellar medium masses for Arp 220 east and west and NGC 6240 of 1.9, 4.2, and 1.6 × 10{sup 9} M {sub ☉}within radii of 69, 65, and 190 pc. The HCN emission was modeled to derive the emissivity distribution as a function of radius and the kinematics of each nuclear disk, yielding dynamical masses consistent with the masses and sizes derived from the dust emission. In Arp 220, the major dust and gas concentrations are at radii less than 50 pc in both counter-rotating nuclear disks. The thickness of the disks in Arp 220 estimated from the velocity dispersion and rotation velocities are 10-20 pc and the mean gas densities are n{sub H{sub 2}}∼10{sup 5} cm{sup –3} at R <50 pc. We develop an analytic treatment for the molecular excitation (including photon trapping), yielding volume densities for both the HCN and CS emission with n {sub H2} ∼ 2 × 10{sup 5} cm{sup –3}. The agreement of the mean density from the total mass and size with that required for excitation suggests that the volume is essentially filled with dense gas, i.e., it is not cloudy or like swiss cheese.

ALMA IMAGING OF HCN, CS, AND DUST IN ARP 220 AND NGC 6240

International Nuclear Information System (INIS)

Scoville, Nick; Manohar, Swarnima; Murchikova, Lena; Sheth, Kartik; Walter, Fabian; Zschaechner, Laura; Yun, Min; Koda, Jin; Sanders, David; Barnes, Joshua; Thompson, Todd; Robertson, Brant; Tacconi, Linda; Narayanan, Desika; Genzel, Reinhard; Davies, Richard; Hernquist, Lars; Brown, Robert; Hayward, Christopher C.; Kartaltepe, Jeyhan

2015-01-01

We report ALMA Band 7 (350 GHz) imaging at 0.''4-0.''6 resolution and Band 9 (696 GHz) at ∼0.''25 resolution of the luminous IR galaxies Arp 220 and NGC 6240. The long wavelength dust continuum is used to estimate interstellar medium masses for Arp 220 east and west and NGC 6240 of 1.9, 4.2, and 1.6 × 10 9 M ☉ within radii of 69, 65, and 190 pc. The HCN emission was modeled to derive the emissivity distribution as a function of radius and the kinematics of each nuclear disk, yielding dynamical masses consistent with the masses and sizes derived from the dust emission. In Arp 220, the major dust and gas concentrations are at radii less than 50 pc in both counter-rotating nuclear disks. The thickness of the disks in Arp 220 estimated from the velocity dispersion and rotation velocities are 10-20 pc and the mean gas densities are n H 2 ∼10 5  cm –3 at R <50 pc. We develop an analytic treatment for the molecular excitation (including photon trapping), yielding volume densities for both the HCN and CS emission with n H2 ∼ 2 × 10 5  cm –3 . The agreement of the mean density from the total mass and size with that required for excitation suggests that the volume is essentially filled with dense gas, i.e., it is not cloudy or like swiss cheese

Investigating the Spatial Structure of HCN Emission in Comet C/2012 F6 (Lemmon)

Science.gov (United States)

Booth, Shawn; Burkhardt, Andrew; Corby, Joanna; Dollhopf, Niklaus; Rawlings, Mark; Remijan, Anthony

2015-11-01

Comets are of particular interest in the field of Astrochemistry as they can be used as a direct probe of formation chemistry of the Solar System. Originating in the Oort Cloud reservoir, these long period objects experience relatively limited solar influence. The majority of cometary material (water, methane and ammonia ices) has remained in the same state as when it formed. These ices are precursors to more complex molecules which have been shown to form amino acids that are crucial for the development of life. HCN, or hydrogen cyanide, is of particular interest because it can form the nucleobase adenine (C5H5N5). The goals of this project are to map the HCN distribution of Comet C/2012 F6 (Lemmon) and to show the simultaneous observation capabilities of the Atacama Large Millimeter/Submillimeter Array (ALMA), which allows the extraction of 7-m array, 12-m array and single dish observation data. On UT 2013 May 11, Comet Lemmon was observed using ALMA. The Cycle 1 configuration was used with the Band 6 receivers, with a 1.5 GHz range centered on the HCN transition at 265.86 GHz, which gave a spectral resolution of 0.07 km/s. We show that Comet Lemmon has both a compact HCN region (found with the 12-m array) and also an extended component, forming a tail-like structure in the anti-motion direction (found with the 7-m array). We were also able to extract the autocorrelation data (single dish) and show that it is viable. This project was supported and funded by NRAO in conjunction with the National Science Foundation (NSF), with special thanks to the Astronomy Department at University of Virginia.

The HCN-Water Ratio in the Planet Formation Region of Disks

NARCIS (Netherlands)

Najita, J.; Carr, J.; Pontoppidan, K.; Salyk, C.; Dishoeck, van E.F.; Blake, G.

2013-01-01

We find a trend between the mid-infrared HCN/H$_{2}$O flux ratio and submillimeter disk mass among T Tauri stars in Taurus. While it may seem puzzling that the molecular emission properties of the inner disk ({lt}few AU) are related to the properties of the outer disk (beyond ~{}20 AU) probed by the

Molecular Line Emission as a Tool for Galaxy Observations (LEGO). I. HCN as a tracer of moderate gas densities in molecular clouds and galaxies

Science.gov (United States)

Kauffmann, Jens; Goldsmith, Paul F.; Melnick, Gary; Tolls, Volker; Guzman, Andres; Menten, Karl M.

2017-09-01

Trends observed in galaxies, such as the Gao & Solomon relation, suggest a linear relationship between the star formation rate and the mass of dense gas available for star formation. Validation of such trends requires the establishment of reliable methods to trace the dense gas in galaxies. One frequent assumption is that the HCN (J = 1-0) transition is unambiguously associated with gas at H2 densities ≫ 104 cm-3. If so, the mass of gas at densities ≫ 104 cm-3 could be inferred from the luminosity of this emission line, LHCN (1-0). Here we use observations of the Orion A molecular cloud to show that the HCN (J = 1-0) line traces much lower densities 103 cm-3 in cold sections of this molecular cloud, corresponding to visual extinctions AV ≈ 6 mag. We also find that cold and dense gas in a cloud like Orion produces too little HCN emission to explain LHCN (1-0) in star forming galaxies, suggesting that galaxies might contain a hitherto unknown source of HCN emission. In our sample of molecules observed at frequencies near 100 GHz (also including 12CO, 13CO, C18O, CN, and CCH), N2H+ is the only species clearly associated with relatively dense gas.

Substitutional HCN- molecular ions in KCN crystal: a paramagnetic probe in a ferroelastic material

International Nuclear Information System (INIS)

Weid, J.P. von der; Carmo, L.C.S. do; Ribeiro, S.C.

1978-01-01

The HCN - molecular ion was produced in single crystals of KCN: 10 -2 OH - irradiated by UV light at 77 K. The spin Hamiltonian parameters were measured at 60 K and the temperature dependence of the spectrum was investigated between 60 K and 170 K. This temperature dependence is explained by the rapid motion of the molecule with the increasing temperature and the elastic interaction of the molecule with the surrounding ions. Using the similarity between the paramagnetic HCN - molecule and the CN - ions of the host lattice a qualitative picture of the local phenomena occuring in the ferroelastic phase of KCN could be made and the energy of the elastic interaction between CN - was estimated of the order of 7 meV [pt

CO, CS, and HCN in a clustering of reflection nebulae in Monoceros

International Nuclear Information System (INIS)

Kutner, M.L.; Tucker, K.D.

1975-01-01

Carbon monoxide line emission at lambda=2.6 mm has been observed over an area of approx.3 1/2degreetimes3 1/2degree in L1646, a diffuse dust cloud containing a grouping of reflection nebulae. The H 2 mass is estimated from the CO observations to be >3.2times10 4 M/sub sun/. Five CO emission peaks are observed, each apparently associated with at least one reflection nebula, with the strongest peak at α (1950) =6)05)20), delta (1950) =-6degree22'30''. Around this position, extended (10'times10') emission is observed from HCN and CS, suggesting a core with H 2 density approximately-less-than8times10 4 cm -3 . This core appears to be rotating with Ωgreater than or equal to7.4times10 -14 s -1 . There is also evidence for self-absorption in the CO line in this direction, suggestive of a collapsing cloud. (auth)

United States Historical Climatology Network (US HCN) monthly temperature and precipitation data

Energy Technology Data Exchange (ETDEWEB)

Daniels, R.C. [ed.] [Univ. of Tennessee, Knoxville, TN (United States). Energy, Environment and Resources Center; Boden, T.A. [ed.] [Oak Ridge National Lab., TN (United States); Easterling, D.R.; Karl, T.R.; Mason, E.H.; Hughes, P.Y.; Bowman, D.P. [National Climatic Data Center, Asheville, NC (United States)

1996-01-11

This document describes a database containing monthly temperature and precipitation data for 1221 stations in the contiguous United States. This network of stations, known as the United States Historical Climatology Network (US HCN), and the resulting database were compiled by the National Climatic Data Center, Asheville, North Carolina. These data represent the best available data from the United States for analyzing long-term climate trends on a regional scale. The data for most stations extend through December 31, 1994, and a majority of the station records are serially complete for at least 80 years. Unlike many data sets that have been used in past climate studies, these data have been adjusted to remove biases introduced by station moves, instrument changes, time-of-observation differences, and urbanization effects. These monthly data are available free of charge as a numeric data package (NDP) from the Carbon Dioxide Information Analysis Center. The NDP includes this document and 27 machine-readable data files consisting of supporting data files, a descriptive file, and computer access codes. This document describes how the stations in the US HCN were selected and how the data were processed, defines limitations and restrictions of the data, describes the format and contents of the magnetic media, and provides reprints of literature that discuss the editing and adjustment techniques used in the US HCN.

A new ab initio potential energy surface for the collisional excitation of HCN by para- and ortho-H{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Denis-Alpizar, Otoniel, E-mail: otonieldenisalpizar@gmail.com [Université de Bordeaux, ISM, CNRS UMR 5255, 33405 Talence Cedex (France); Departamento de Física, Universidad de Matanzas, Matanzas 40100 (Cuba); Kalugina, Yulia [LOMC - UMR 6294, CNRS-Université du Havre, 25 rue Philippe Lebon, BP 540, 76058, Le Havre (France); Department of Optics and Spectroscopy, Tomsk State University, 36 Lenin av., Tomsk 634050 (Russian Federation); Stoecklin, Thierry [Université de Bordeaux, ISM, CNRS UMR 5255, 33405 Talence Cedex (France); Vera, Mario Hernández [LOMC - UMR 6294, CNRS-Université du Havre, 25 rue Philippe Lebon, BP 540, 76058, Le Havre (France); Instituto Superior de Tecnologías y Ciencias Aplicadas, Quinta de Los Molinos, Plaza, La Habana 10600 (Cuba); Lique, François, E-mail: francois.lique@univ-lehavre.fr [Departamento de Física, Universidad de Matanzas, Matanzas 40100 (Cuba)

2013-12-14

We present a new four-dimensional potential energy surface for the collisional excitation of HCN by H{sub 2}. Ab initio calculations of the HCN–H{sub 2} van der Waals complex, considering both molecules as rigid rotors, were carried out at the explicitly correlated coupled cluster with single, double, and perturbative triple excitations [CCSD(T)-F12a] level of theory using an augmented correlation-consistent triple zeta (aVTZ) basis set. The equilibrium structure is linear HCN–H{sub 2} with the nitrogen pointing towards H{sub 2} at an intermolecular separation of 7.20 a{sub 0}. The corresponding well depth is −195.20 cm{sup −1}. A secondary minimum of −183.59 cm{sup −1} was found for a T-shape configuration with the H of HCN pointing to the center of mass of H{sub 2}. We also determine the rovibrational energy levels of the HCN–para-H{sub 2} and HCN–ortho-H{sub 2} complexes. The calculated dissociation energies for the para and ortho complexes are 37.79 cm{sup −1} and 60.26 cm{sup −1}, respectively. The calculated ro-vibrational transitions in the HCN–H{sub 2} complex are found to agree by more than 0.5% with the available experimental data, confirming the accuracy of the potential energy surface.

Chemical content of the circumstellar envelope of the oxygen-rich AGB star R Doradus. Non-LTE abundance analysis of CO, SiO, and HCN

Science.gov (United States)

Van de Sande, M.; Decin, L.; Lombaert, R.; Khouri, T.; de Koter, A.; Wyrowski, F.; De Nutte, R.; Homan, W.

2018-01-01

Context. The stellar outflows of low- to intermediate-mass stars are characterised by a rich chemistry. Condensation of molecular gas species into dust grains is a key component in a chain of physical processes that leads to the onset of a stellar wind. In order to improve our understanding of the coupling between the micro-scale chemistry and macro-scale dynamics, we need to retrieve the abundance of molecules throughout the outflow. Aims: Our aim is to determine the radial abundance profile of SiO and HCN throughout the stellar outflow of R Dor, an oxygen-rich AGB star with a low mass-loss rate. SiO is thought to play an essential role in the dust-formation process of oxygen-rich AGB stars. The presence of HCN in an oxygen-rich environment is thought to be due to non-equilibrium chemistry in the inner wind. Methods: We analysed molecular transitions of CO, SiO, and HCN measured with the APEX telescope and all three instruments on the Herschel Space Observatory, together with data available in the literature. Photometric data and the infrared spectrum measured by ISO-SWS were used to constrain the dust component of the outflow. Using both continuum and line radiative transfer methods, a physical envelope model of both gas and dust was established. We performed an analysis of the SiO and HCN molecular transitions in order to calculate their abundances. Results: We have obtained an envelope model that describes the dust and the gas in the outflow, and determined the abundance of SiO and HCN throughout the region of the stellar outflow probed by our molecular data. For SiO, we find that the initial abundance lies between 5.5 × 10-5 and 6.0 × 10-5 with respect to H2. The abundance profile is constant up to 60 ± 10 R∗, after which it declines following a Gaussian profile with an e-folding radius of 3.5 ± 0.5 × 1013 cm or 1.4 ± 0.2 R∗. For HCN, we find an initial abundance of 5.0 × 10-7 with respect to H2. The Gaussian profile that describes the decline

Signal detection circuit design of HCN measurement system based on TDLAS

Science.gov (United States)

He, Chungui; Zhang, Yujun; Chen, Chen; Lu, Yibing; Liu, Guohua; Gao, Yanwei; You, Kun; He, Ying; Zhang, Kai; Liu, Wenqing

2016-10-01

Hydrogen cyanide gas leakage may exist in the petrochemical industry, smelting plant, and other industrial processes, causing serious harm to the environment, and even threatening the safety of personnel. So the continuous detection of HCN gas plays an important role in the prevention of risk in production process and storage environment that existing hydrogen cyanide gas. The Tunable Diode Laser Technology (TDLAS) has advantages of non-contact, high sensitivity, high selectivity, and fast response time, etc., which is one of the ideal method of gas detection technologies and can be used to measure the hydrogen cyanide concentration. This paper studies the HCN detection system based on TDLAS technology, selects the absorption lines of hydrogen cyanide in 6539.12cm-1, and utilizes the center wavelength of 1.529μm distributed feedback (DFB) laser as a light source. It is discussed in detail on technical requirements of a high frequency modulated laser signal detection circuit, including noise level, gain, and bandwidth. Based on the above theory, the high frequency modulation preamplifier circuit and main amplifier circuit are designed for InGaAs photoelectric detector. The designed circuits are calculation analyzed with corresponding formula and simulation analyzed based on the Multisim software.

Infrared Solar Spectroscopic Measurements of Free Tropospheric CO, C2H6, and HCN above Mauna Loa, Hawaii: Seasonal Variations and Evidence for Enhanced Emissions from the Southeast Asian Tropical Fires of 1997-1998

Science.gov (United States)

Rinsland, C. P.; Goldman, A.; Murcray, F. J.; Stephen, T. M.; Pougatchev, N. S.; Fishman, J.; David, S. J.; Blatherwick, R. D.; Novelli, P. C.; Jones, N. B.

1999-01-01

High spectral resolution (0.003 per cm) infrared solar absorption measurements of CO, C2H6, and HCN have been recorded at the Network for the Detection of Stratospheric Change station on Mauna Loa, Hawaii, (19.5N, 155.6W, altitude 3.4 km). The observations were obtained on over 250 days between August 1995 and February 1998. Column measurements are reported for the 3.4-16 km altitude region, which corresponds approximately to the free troposphere above the station. Average CO mixing ratios computed for this layer have been compared with flask sampling CO measurements obtained in situ at the station during the same time period. Both show asymmetrical seasonal cycles superimposed on significant variability. The first 2 years of observations exhibit a broad January-April maximum and a sharper CO minimum during late summer. The C2H6 and CO 3.4-16 km columns were highly correlated throughout the observing period with the C2H6/CO slope intermediate between higher and lower values derived from similar infrared spectroscopic measurements at 32'N and 45'S latitude, respectively. Variable enhancements in CO, C2H6, and particularly HCN were observed beginning in about September 1997. The maximum HCN free tropospheric monthly mean column observed in November 1997 corresponds to an average 3.4-16 km mixing ratio of 0.7 ppbv (1 ppbv = 10(exp -9) per unit volume), more than a factor of 3 above the background level. The HCN enhancements continued through the end of the observational series. Back-trajectory calculations suggest that the emissions originated at low northern latitudes in southeast Asia. Surface CO mixing ratios and the C2H6 tropospheric columns measured during the same time also showed anomalous autumn 1997 maxima. The intense and widespread tropical wild fires that burned during the strong El Nino warm phase of 1997- 1998 are the likely source of the elevated emission products.

Fluoxetine ameliorates cognitive impairments induced by chronic cerebral hypoperfusion via down-regulation of HCN2 surface expression in the hippocampal CA1 area in rats.

Science.gov (United States)

Luo, Pan; Zhang, Xiaoxue; Lu, Yun; Chen, Cheng; Li, Changjun; Zhou, Mei; Lu, Qing; Xu, Xulin; Shen, Guanxin; Guo, Lianjun

2016-01-01

Chronic cerebral hypoperfusion (CCH) causes cognitive impairments and increases the risk of Alzheimer's disease (AD) and vascular dementia (VD) through several biologically plausible pathways, yet the underlying neurobiological mechanisms are still poorly understood. In this study, we investigated whether fluoxetine, a selective serotonin reuptake inhibitor (SSRI), could play a neuroprotective role against chronic cerebral hypoperfusion injury and to clarify underlying mechanisms of its efficacy. Rats were subjected to permanent bilateral occlusion of the common carotid arteries (two-vessel occlusion, 2VO). Two weeks later, rats were treated with 30 mg/kg fluoxetine (intragastric injection, i.g.) for 6 weeks. Cognitive function was evaluated by Morris water maze (MWM) and novel objects recognition (NOR) test. Long-term potentiation (LTP) was used to address the underlying synaptic mechanisms. Western blotting was used to quantify the protein levels. Our results showed that fluoxetine treatment significantly improved the cognitive impairments caused by 2VO, accompanied with a reversion of 2VO-induced inhibitory of LTP. Furthermore, 2VO caused an up-regulation of hyperpolarization-activated cyclic nucleotide-gated channel 2 (HCN2) surface expressions in the hippocampal CA1 area and fluoxetine also effectively recovered the disorder of HCN2 surface expressions, which may be a possible mechanism that fluoxetine treatment ameliorates cognitive impairments in rats with CCH. Copyright © 2015 Elsevier Inc. All rights reserved.

Dormancy alleviation by NO or HCN leading to decline of protein carbonylation levels in apple (Malus domestica Borkh.) embryos.

Science.gov (United States)

Krasuska, Urszula; Ciacka, Katarzyna; Dębska, Karolina; Bogatek, Renata; Gniazdowska, Agnieszka

2014-08-15

Deep dormancy of apple (Malus domestica Borkh.) embryos can be overcome by short-term pre-treatment with nitric oxide (NO) or hydrogen cyanide (HCN). Dormancy alleviation of embryos modulated by NO or HCN and the first step of germination depend on temporary increased production of reactive oxygen species (ROS). Direct oxidative attack on some amino acid residues or secondary reactions via reactive carbohydrates and lipids can lead to the formation of protein carbonyl derivatives. Protein carbonylation is a widely accepted covalent and irreversible modification resulting in inhibition or alteration of enzyme/protein activities. It also increases the susceptibility of proteins to proteolytic degradation. The aim of this work was to investigate protein carbonylation in germinating apple embryos, the dormancy of which was removed by pre-treatment with NO or HCN donors. It was performed using a quantitative spectrophotometric method, while patterns of carbonylated protein in embryo axes were analyzed by immunochemical techniques. The highest concentration of protein carbonyl groups was observed in dormant embryos. It declined in germinating embryos pre-treated with NO or HCN, suggesting elevated degradation of modified proteins during seedling formation. A decrease in the concentration of carbonylated proteins was accompanied by modification in proteolytic activity in germinating apple embryos. A strict correlation between the level of protein carbonyl groups and cotyledon growth and greening was detected. Moreover, direct in vitro carbonylation of BSA treated with NO or HCN donors was analyzed, showing action of both signaling molecules as protein oxidation agents. Copyright © 2014 Elsevier GmbH. All rights reserved.

Hyperfine anomalies of HCN in cold dark clouds

International Nuclear Information System (INIS)

Walmsley, C.M.; Churchwell, E.; Nash, A.; Fitzpatrick, E.; and Physics Department, University of Illinois at Urbana-Champaign)

1982-01-01

We report observations of the J = 1→0 line of HCN measured toward six positions in nearby low-temperature dark clouds. The measured relative intensities of the hyperfine components of the J = 1→0 line are anomalous in that the F = 0→1 transition is stronger than would be expected if all three components (F = 2→1, F = 1→1, F = 0→1) had equal excitation temperatures. Differences of approximately 20% in the populations per sublevel of J = 1 could account for the observations. The results are in contrast to the situation observed in warmer molecular clouds associated with H II regions where the F = 1→1 line is anomalously weak. The apparent overpopulation of J = 1, F = 0 in dark clouds may be related to the phenomenon observed in the J = 1→0 transitions of HCO + and HNC in the same objects where 13 C substituted version of these species is found to be stronger than the 12 C species

Millimeterwave spectroscopy of active laser plasmas; the excited vibrational states of HCN

International Nuclear Information System (INIS)

De Lucia, F.C.; Helminger, P.A.

1977-01-01

Millimeter and submillimeter microwave techniques have been used for the spectroscopic study of an HCN laser plasma. Forty-seven rotational transitions in 12 excited vibrational states have been observed. Numerous rotational, vibrational, and perturbation parameters have been calculated from these data. A discussion of experimental techniques is included

Lewis acid-base interactions in weakly bound formaldehyde complexes with CO2, HCN, and FCN: considerations on the cooperative H-bonding effects.

Science.gov (United States)

Rivelino, Roberto

2008-01-17

Ab initio quantum chemistry calculations reveal that HCN and mainly FCN can form Lewis acid-base complexes with formaldehyde associated with cooperative H bonds, as first noticed by Wallen et al. (Blatchford, M. A.; Raveendran, P.; Wallen, S. L. J. Am. Chem. Soc. 2002, 124, 14818-14819) for CO2-philic materials under supercritical conditions. The present results, obtained with MP2(Full)/aug-cc-pVDZ calculations, show that the degeneracy of the nu(2) mode in free HCN or FCN is removed upon complexation in the same fashion as that of CO2. The splitting of these bands along with the electron structure analysis provides substantial evidence of the interaction of electron lone pairs of the carbonyl oxygen with the electron-deficient carbon atom of the cyanides. Also, this work investigates the role of H bonds acting as additional stabilizing interactions in the complexes by performing the energetic and geometric characterization.

Increased expression of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in reactive astrocytes following ischemia

Czech Academy of Sciences Publication Activity Database

Honsa, Pavel; Pivoňková, Helena; Harantová, Lenka; Butenko, Olena; Kriška, Ján; Džamba, Dávid; Rusňáková, Vendula; Valihrach, Lukáš; Kubista, Mikael; Anděrová, Miroslava

2014-01-01

Roč. 62, č. 12 (2014), s. 2004-2021 ISSN 0894-1491 R&D Projects: GA ČR GA13-02154S; GA ČR(CZ) GBP304/12/G069; GA MŠk(CZ) ED1.1.00/02.0109 Grant - others:GA MŠk(CZ) CZ.1.07/2.3.00/30.0045 Institutional support: RVO:68378041 ; RVO:86652036 Keywords : Astrocytes * focal and global cerebral ischemia * HCN channels Subject RIV: FH - Neurology Impact factor: 6.031, year: 2014

Plasma density calculation based on the HCN waveform data

International Nuclear Information System (INIS)

Chen Liaoyuan; Pan Li; Luo Cuiwen; Zhou Yan; Deng Zhongchao

2004-01-01

A method to improve the plasma density calculation is introduced using the base voltage and the phase zero points obtained from the HCN interference waveform data. The method includes making the signal quality higher by putting the signal control device and the analog-to-digit converters in the same location and charging them by the same power, and excluding the noise's effect according to the possible changing rate of the signal's phase, and to make the base voltage more accurate by dynamical data processing. (authors)

Modulation of thalamocortical oscillations by TRIP8b, an auxiliary subunit for HCN channels

NARCIS (Netherlands)

Zobeiri, M.; Chaudhary, R.; Datunashvili, M.; Heuermann, R.J.; Lüttjohann, A.; Narayanan, V.; Balfanz, S.; Meuth, P.; Chetkovich, D.M.; Pape, H.C.; Baumann, A.; Luijtelaar, E.L.J.M. van; Budde, T.

2018-01-01

Hyperpolarization-activated cyclic nucleotide-gated cation (HCN) channels have important functions in controlling neuronal excitability and generating rhythmic oscillatory activity. The role of tetratricopeptide repeat-containing Rab8b-interacting protein (TRIP8b) in regulation of

IRRADIATION OF ETHYLENE DILUTED IN SOLID NITROGEN WITH VACUUM ULTRAVIOLET LIGHT AND ELECTRONS: ITS IMPLICATIONS FOR THE FORMATION OF HCN AND HNC

Energy Technology Data Exchange (ETDEWEB)

Chen, Hui-Fen [Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, 100, Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Liu, Meng-Chen; Chen, Sian-Cong; Huang, Tzu-Ping; Wu, Yu-Jong, E-mail: yjwu@nsrrc.org.tw [National Synchrotron Radiation Research Center, No. 101, Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan (China)

2015-05-01

Chemical reactions of C{sub 2}H{sub 4} dispersed in solid nitrogen at 10 K that occur upon irradiation with Lyα light at a wavelength of 121.6 nm and 500 eV electrons were investigated by measuring the infrared absorption spectra. Photolysis of the matrix samples with 121.6 nm light yielded products, including C{sub 2}H{sub 2}, CN, and isomers of C{sub 2}N{sub 2}, as well as a pair of HCN and HNC. In contrast, electron bombardment of similar matrix samples mainly resulted in the generation of N{sub 3}, C{sub 2}H{sub 2}, C{sub 2}H{sub 3}, C{sub 3}H{sub 2}, and C{sub 3}N{sup −}. Mechanisms of the reactions that occur during the photolysis and electron-radiation of the matrix samples are discussed. The results of the study provide insights into the formation of HNC and HCN, as well as nitriles, in N{sub 2}-rich ice samples containing a small proportion of C{sub 2}H{sub 4}.

SUBMILLIMETER-HCN DIAGRAM FOR ENERGY DIAGNOSTICS IN THE CENTERS OF GALAXIES

Energy Technology Data Exchange (ETDEWEB)

Izumi, Takuma; Kohno, Kotaro [Institute of Astronomy, School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Aalto, Susanne [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Observatory, SE-439 94 Onsala (Sweden); Espada, Daniel; Martín, Sergio; Nakanishi, Kouichiro [Joint ALMA Observatory, Alonso de Córdova, 3107, Vitacura, Santiago 763-0355 (Chile); Fathi, Kambiz [Stockholm Observatory, Department of Astronomy, Stockholm University, AlbaNova Centre, SE-106 91 Stockholm (Sweden); Harada, Nanase; Hsieh, Pei-Ying; Matsushita, Satoki [Academia Sinica, Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China); Hatsukade, Bunyo; Imanishi, Masatoshi [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Krips, Melanie [Institut de Radio Astronomie Millimétrique, 300 rue de la Piscine, Domaine Universitaire, F-38406 St. Martin d’Hères (France); Meier, David S. [Department of Physics, New Mexico Institute of Mining and Technology, 801 Leroy Place, Soccoro, NM 87801 (United States); Nakai, Naomasa [Department of Physics, Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Ten-nodai, Tsukuba, Ibaraki 305-8571 (Japan); Schinnerer, Eva [Max Planck Institute for Astronomy, Königstuhl 17, Heidelberg D-69117 (Germany); Sheth, Kartik [NASA, 300 E Street SW, Washington, DC 20546 (United States); Terashima, Yuichi [Department of Physics, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577 (Japan); Turner, Jean L., E-mail: takumaizumi@ioa.s.u-tokyo.ac.jp [Department of Physics and Astronomy, UCLA, 430 Portola Plaza, Los Angeles, CA 90095-1547 (United States)

2016-02-10

Compiling data from literature and the Atacama Large Millimeter/submillimeter Array archive, we show enhanced HCN(4–3)/HCO{sup +}(4–3) and/or HCN(4–3)/CS(7–6) integrated intensity ratios in circumnuclear molecular gas around active galactic nuclei (AGNs) compared to those in starburst (SB) galaxies (submillimeter HCN enhancement). The number of sample galaxies is significantly increased from our previous work. We expect that this feature could potentially be an extinction-free energy diagnostic tool of nuclear regions of galaxies. Non-LTE radiative transfer modelings of the above molecular emission lines involving both collisional and radiative excitation, as well as a photon trapping effect, were conducted to investigate the cause of the high line ratios in AGNs. As a result, we found that enhanced abundance ratios of HCN to HCO{sup +} and HCN to CS in AGNs as compared to SB galaxies by a factor of a few to even ≳10 are a plausible explanation for the submillimeter HCN enhancement. However, a counterargument of a systematically higher gas density in AGNs than in SB galaxies can also be a plausible scenario. Although we cannot fully distinguish these two scenarios at this moment owing to an insufficient amount of multi-transition, multi-species data, the former scenario is indicative of abnormal chemical composition in AGNs. Regarding the actual mechanism to realize the composition, we suggest that it is difficult with conventional gas-phase X-ray-dominated region ionization models to reproduce the observed high line ratios. We might have to take into account other mechanisms such as neutral–neutral reactions that are efficiently activated in high-temperature environments and/or mechanically heated regions to further understand the high line ratios in AGNs.

Ab initio calculation of a global potential, vibrational energies, and wave functions for HCN/HNC, and a simulation of the (A-tilde)-(X-tilde) emission spectrum

Science.gov (United States)

Bowman, Joel M.; Gazdy, Bela; Bentley, Joseph A.; Lee, Timothy J.; Dateo, Christopher E.

1993-01-01

A potential energy surface for the HCN/HNC system which is a fit to extensive, high-quality ab initio, coupled-cluster calculations is presented. All HCN and HNC states with energies below the energy of the first delocalized state are reported and characterized. Vibrational transition energies are compared with all available experimental data on HCN and HNC, including high CH-overtone states up to 23,063/cm. A simulation of the (A-tilde)-(X-tilde) stimulated emission pumping (SEP) spectrum is also reported, and the results are compared to experiment. Franck-Condon factors are reported for odd bending states of HCN, with one quantum of vibrational angular momentum, in order to compare with the recent assignment by Jonas et al. (1992), on the basis of axis-switching arguments of a number of previously unassigned states in the SEP spectrum.

Reduction of nitrogen compounds in oceanic basement and its implications for HCN formation and abiotic organic synthesis.

Science.gov (United States)

Holm, Nils G; Neubeck, Anna

2009-10-22

Hydrogen cyanide is an excellent organic reagent and is central to most of the reaction pathways leading to abiotic formation of simple organic compounds containing nitrogen, such as amino acids, purines and pyrimidines. Reduced carbon and nitrogen precursor compounds for the synthesis of HCN may be formed under off-axis hydrothermal conditions in oceanic lithosphere in the presence of native Fe and Ni and are adsorbed on authigenic layer silicates and zeolites. The native metals as well as the molecular hydrogen reducing CO2 to CO/CH4 and NO3-/NO2- to NH3/NH4+ are a result of serpentinization of mafic rocks. Oceanic plates are conveyor belts of reduced carbon and nitrogen compounds from the off-axis hydrothermal environments to the subduction zones, where compaction, dehydration, desiccation and diagenetic reactions affect the organic precursors. CO/CH4 and NH3/NH4+ in fluids distilled out of layer silicates and zeolites in the subducting plate at an early stage of subduction will react upon heating and form HCN, which is then available for further organic reactions to, for instance, carbohydrates, nucleosides or even nucleotides, under alkaline conditions in hydrated mantle rocks of the overriding plate. Convergent margins in the initial phase of subduction must, therefore, be considered the most potent sites for prebiotic reactions on Earth. This means that origin of life processes are, perhaps, only possible on planets where some kind of plate tectonics occur.

Reduction of nitrogen compounds in oceanic basement and its implications for HCN formation and abiotic organic synthesis

Directory of Open Access Journals (Sweden)

Neubeck Anna

2009-10-01

Full Text Available Abstract Hydrogen cyanide is an excellent organic reagent and is central to most of the reaction pathways leading to abiotic formation of simple organic compounds containing nitrogen, such as amino acids, purines and pyrimidines. Reduced carbon and nitrogen precursor compounds for the synthesis of HCN may be formed under off-axis hydrothermal conditions in oceanic lithosphere in the presence of native Fe and Ni and are adsorbed on authigenic layer silicates and zeolites. The native metals as well as the molecular hydrogen reducing CO2 to CO/CH4 and NO3-/NO2- to NH3/NH4+ are a result of serpentinization of mafic rocks. Oceanic plates are conveyor belts of reduced carbon and nitrogen compounds from the off-axis hydrothermal environments to the subduction zones, where compaction, dehydration, desiccation and diagenetic reactions affect the organic precursors. CO/CH4 and NH3/NH4+ in fluids distilled out of layer silicates and zeolites in the subducting plate at an early stage of subduction will react upon heating and form HCN, which is then available for further organic reactions to, for instance, carbohydrates, nucleosides or even nucleotides, under alkaline conditions in hydrated mantle rocks of the overriding plate. Convergent margins in the initial phase of subduction must, therefore, be considered the most potent sites for prebiotic reactions on Earth. This means that origin of life processes are, perhaps, only possible on planets where some kind of plate tectonics occur.

I h and HCN channels in murine spiral ganglion neurons: tonotopic variation, local heterogeneity, and kinetic model.

Science.gov (United States)

Liu, Qing; Manis, Paul B; Davis, Robin L

2014-08-01

One of the major contributors to the response profile of neurons in the auditory pathways is the I h current. Its properties such as magnitude, activation, and kinetics not only vary among different types of neurons (Banks et al., J Neurophysiol 70:1420-1432, 1993; Fu et al., J Neurophysiol 78:2235-2245, 1997; Bal and Oertel, J Neurophysiol 84:806-817, 2000; Cao and Oertel, J Neurophysiol 94:821-832, 2005; Rodrigues and Oertel, J Neurophysiol 95:76-87, 2006; Yi et al., J Neurophysiol 103:2532-2543, 2010), but they also display notable diversity in a single population of spiral ganglion neurons (Mo and Davis, J Neurophysiol 78:3019-3027, 1997), the first neural element in the auditory periphery. In this study, we found from somatic recordings that part of the heterogeneity can be attributed to variation along the tonotopic axis because I h in the apical neurons have more positive half-activation voltage levels than basal neurons. Even within a single cochlear region, however, I h current properties are not uniform. To account for this heterogeneity, we provide immunocytochemical evidence for variance in the intracellular density of the hyperpolarization-activated cyclic nucleotide-gated channel α-subunit 1 (HCN1), which mediates I h current. We also observed different combinations of HCN1 and HCN4 α-subunits from cell to cell. Lastly, based on the physiological data, we performed kinetic analysis for the I h current and generated a mathematical model to better understand varied I h on spiral ganglion function. Regardless of whether I h currents are recorded at the nerve terminals (Yi et al., J Neurophysiol 103:2532-2543, 2010) or at the somata of spiral ganglion neurons, they have comparable mean half-activation voltage and induce similar resting membrane potential changes, and thus our model may also provide insights into the impact of I h on synaptic physiology.

Sugar-to-base correlation in nucleic acids with a 5D APSY-HCNCH or two 3D APSY-HCN experiments

Energy Technology Data Exchange (ETDEWEB)

Kraehenbuehl, Barbara; Hofmann, Daniela; Maris, Christophe; Wider, Gerhard, E-mail: gsw@mol.biol.ethz.ch [Institute of Molecular Biology and Biophysics (Switzerland)

2012-02-15

A five-dimensional (5D) APSY (automated projection spectroscopy) HCNCH experiment is presented, which allows unambiguous correlation of sugar to base nuclei in nucleic acids. The pulse sequence uses multiple quantum (MQ) evolution which enables long constant-time evolution periods in all dimensions, an improvement that can also benefit non-APSY applications. Applied with an RNA with 23 nucleotides the 5D APSY-HCNCH experiment produced a complete and highly precise 5D chemical shift list within 1.5 h. Alternatively, and for molecules where the out-and-stay 5D experiment sensitivity is not sufficient, a set of out-and-back 3D APSY-HCN experiments is proposed: an intra-base (3D APSY-b-HCN) experiment in an MQ or in a TROSY version, and an MQ sugar-to-base (3D APSY-s-HCN) experiment. The two 3D peak lists require subsequent matching via the N1/9 chemical shift values to one 5D peak list. Optimization of the 3D APSY experiments for maximal precision in the N1/9 dimension allowed matching of all {sup 15}N chemical shift values contained in both 3D peak lists. The precise 5D chemical shift correlation lists resulting from the 5D experiment or a pair of 3D experiments also provide a valuable basis for subsequent connection to chemical shifts derived with other experiments.

Sugar-to-base correlation in nucleic acids with a 5D APSY-HCNCH or two 3D APSY-HCN experiments

International Nuclear Information System (INIS)

Krähenbühl, Barbara; Hofmann, Daniela; Maris, Christophe; Wider, Gerhard

2012-01-01

A five-dimensional (5D) APSY (automated projection spectroscopy) HCNCH experiment is presented, which allows unambiguous correlation of sugar to base nuclei in nucleic acids. The pulse sequence uses multiple quantum (MQ) evolution which enables long constant-time evolution periods in all dimensions, an improvement that can also benefit non-APSY applications. Applied with an RNA with 23 nucleotides the 5D APSY-HCNCH experiment produced a complete and highly precise 5D chemical shift list within 1.5 h. Alternatively, and for molecules where the out-and-stay 5D experiment sensitivity is not sufficient, a set of out-and-back 3D APSY-HCN experiments is proposed: an intra-base (3D APSY-b-HCN) experiment in an MQ or in a TROSY version, and an MQ sugar-to-base (3D APSY-s-HCN) experiment. The two 3D peak lists require subsequent matching via the N1/9 chemical shift values to one 5D peak list. Optimization of the 3D APSY experiments for maximal precision in the N1/9 dimension allowed matching of all 15 N chemical shift values contained in both 3D peak lists. The precise 5D chemical shift correlation lists resulting from the 5D experiment or a pair of 3D experiments also provide a valuable basis for subsequent connection to chemical shifts derived with other experiments.

Kcne2 deletion uncovers its crucial role in thyroid hormone biosynthesis

Science.gov (United States)

Roepke, Torsten K.; King, Elizabeth C.; Reyna-Neyra, Andrea; Paroder, Monika; Purtell, Kerry; Koba, Wade; Fine, Eugene; Lerner, Daniel J.; Carrasco, Nancy; Abbott, Geoffrey W.

2009-01-01

Thyroid dysfunction affects 1–4% of the population worldwide, causing defects including neurodevelopmental disorders, dwarfism and cardiac arrhythmia. Here, we show that KCNQ1 and KCNE2 form a TSH-stimulated, constitutively-active, thyrocyte K+ channel required for normal thyroid hormone biosynthesis. Targeted disruption of Kcne2 impaired thyroid iodide accumulation up to 8-fold, impaired maternal milk ejection and halved milk T4 content, causing hypothyroidism, 50% reduced litter size, dwarfism, alopecia, goiter, and cardiac abnormalities including hypertrophy, fibrosis, and reduced fractional shortening. The alopecia, dwarfism and cardiac abnormalities were alleviated by T3/T4 administration to pups, by supplementing dams with T4 pre- and postpartum, or by pre-weaning surrogacy with Kcne2+/+ dams; conversely these symptoms were elicited in Kcne2+/+ pups by surrogacy with Kcne2−/− dams. The data identify a critical thyrocyte K+ channel, provide a possible novel therapeutic avenue for thyroid disorders, and predict an endocrine component to some previously-identified KCNE2- and KCNQ1-linked human cardiac arrhythmias. PMID:19767733

Retrieving molecular structural information and tracking HNC/HCN isomerization process with high harmonic generation by ultrashort laser pulses

International Nuclear Information System (INIS)

Nguyen Ngoc Ty; Le Van Hoang; Vu Ngoc Tuoc; Le Anh Thu

2010-01-01

We investigate the possibility of applying the iterative method, suggested in our previous work, for HCN molecule and its HNC isomer. We found that the high-order harmonic generation (HHG) spectra are quite insensitive to the change of H-C (or H-N) bond length so that only the inter-nuclear C-N distance can be retrieved from the high-order harmonic spectra using ultrashort intense lasers. Furthermore, by analyzing the HHG spectra emitted by HCN during the chemical reaction path of isomerization we identify the intensity peaks nearby the stable, metastable and transition states. this finding can be useful for tracking the HNC/HNC isomerization process. (author)

FTIR time-series of biomass burning products (HCN, C2H6, C2H2, CH3OH, and HCOOH at Reunion Island (21° S, 55° E and comparisons with model data

Directory of Open Access Journals (Sweden)

D. B. A. Jones

2012-11-01

Full Text Available Reunion Island (21° S, 55° E, situated in the Indian Ocean at about 800 km east of Madagascar, is appropriately located to monitor the outflow of biomass burning pollution from Southern Africa and Madagascar, in the case of short-lived compounds, and from other Southern Hemispheric landmasses such as South America, in the case of longer-lived species. Ground-based Fourier transform infrared (FTIR solar absorption observations are sensitive to a large number of biomass burning products. We present in this work the FTIR retrieval strategies, suitable for very humid sites such as Reunion Island, for hydrogen cyanide (HCN, ethane (C2H6, acetylene (C2H2, methanol (CH3OH, and formic acid (HCOOH. We provide their total columns time-series obtained from the measurements during August–October 2004, May–October 2007, and May 2009–December 2010. We show that biomass burning explains a large part of the observed seasonal and interannual variability of the chemical species. The correlations between the daily mean total columns of each of the species and those of CO, also measured with our FTIR spectrometer at Reunion Island, are very good from August to November (R ≥ 0.86. This allows us to derive, for that period, the following enhancement ratios with respect to CO: 0.0047, 0.0078, 0.0020, 0.012, and 0.0046 for HCN, C2H6, C2H2, CH3OH, and HCOOH, respectively. The HCN ground-based data are compared to the chemical transport model GEOS-Chem, while the data for the other species are compared to the IMAGESv2 model. We show that using the HCN/CO ratio derived from our measurements (0.0047 in GEOS-Chem reduces the underestimation of the modeled HCN columns compared with the FTIR measurements. The comparisons between IMAGESv2 and the long-lived species C2H6 and C2H2 indicate that the biomass burning emissions used in the model (from the GFED3 inventory are probably underestimated in the late September–October period for all years of measurements, and

Kcne4 Deletion Sex-Dependently Alters Vascular Reactivity

DEFF Research Database (Denmark)

Abbott, Geoffrey W; Jepps, Thomas A

2016-01-01

transcripts, with no striking sex-specific differences. However, Kv7.4 protein expression in females was twice that in males, and was reduced in both sexes by Kcne4 deletion. Our findings confirm a crucial role for KCNE4 in regulation of Kv7 channel activity to modulate vascular tone, and provide the first......Voltage-gated potassium (Kv) channels formed by Kv7 (KCNQ) α-subunits are recognized as crucial for vascular smooth muscle function, in addition to their established roles in the heart (Kv7.1) and the brain (Kv7.2-5). In vivo, Kv7 α-subunits are often regulated by KCNE subfamily ancillary (β...... known molecular mechanism for sex-specificity of this modulation that has important implications for vascular reactivity and may underlie sex-specific susceptibility to cardiovascular diseases....

Modulation of thalamocortical oscillations by TRIP8b, an auxiliary subunit for HCN channels.

Science.gov (United States)

Zobeiri, Mehrnoush; Chaudhary, Rahul; Datunashvili, Maia; Heuermann, Robert J; Lüttjohann, Annika; Narayanan, Venu; Balfanz, Sabine; Meuth, Patrick; Chetkovich, Dane M; Pape, Hans-Christian; Baumann, Arnd; van Luijtelaar, Gilles; Budde, Thomas

2018-04-01

Hyperpolarization-activated cyclic nucleotide-gated cation (HCN) channels have important functions in controlling neuronal excitability and generating rhythmic oscillatory activity. The role of tetratricopeptide repeat-containing Rab8b-interacting protein (TRIP8b) in regulation of hyperpolarization-activated inward current, I h , in the thalamocortical system and its functional relevance for the physiological thalamocortical oscillations were investigated. A significant decrease in I h current density, in both thalamocortical relay (TC) and cortical pyramidal neurons was found in TRIP8b-deficient mice (TRIP8b -/- ). In addition basal cAMP levels in the brain were found to be decreased while the availability of the fast transient A-type K + current, I A , in TC neurons was increased. These changes were associated with alterations in intrinsic properties and firing patterns of TC neurons, as well as intrathalamic and thalamocortical network oscillations, revealing a significant increase in slow oscillations in the delta frequency range (0.5-4 Hz) during episodes of active-wakefulness. In addition, absence of TRIP8b suppresses the normal desynchronization response of the EEG during the switch from slow-wave sleep to wakefulness. It is concluded that TRIP8b is necessary for the modulation of physiological thalamocortical oscillations due to its direct effect on HCN channel expression in thalamus and cortex and that mechanisms related to reduced cAMP signaling may contribute to the present findings.

Chemical evolution. XXI - The amino acids released on hydrolysis of HCN oligomers

Science.gov (United States)

Ferris, J. P.; Wos, J. D.; Nooner, D. W.; Oro, J.

1974-01-01

Major amino acids released by hydrolysis of acidic and basic HCN oligomers are identified by chromatography as Gly, Asp, and diaminosuccinic acid. Smaller amounts of Ala, Ile and alpha-aminoisobutyric acid are also detected. The amino acids released did not change appreciably when the hydrolysis medium was changed from neutral to acidic or basic. The presence of both meso and d, l-diaminosuccinic acids was established by paper chromatography and on an amino acid analyzer.

Inhibition of GluR Current in Microvilli of Sensory Neurons via Na+-Microdomain Coupling Among GluR, HCN Channel, and Na+/K+ Pump

Directory of Open Access Journals (Sweden)

Yasuhiro Kawasaki

2018-04-01

Full Text Available Glutamatergic dendritic EPSPs evoked in cortical pyramidal neurons are depressed by activation of hyperpolarization-activated cyclic nucleotide-gated (HCN channels expressed in dendritic spines. This depression has been attributed to shunting effects of HCN current (Ih on input resistance or Ih deactivation. Primary sensory neurons in the rat mesencephalic trigeminal nucleus (MTN have the somata covered by spine-like microvilli that express HCN channels. In rat MTN neurons, we demonstrated that Ih enhancement apparently diminished the glutamate receptor (GluR current (IGluR evoked by puff application of glutamate/AMPA and enhanced a transient outward current following IGluR (OT-IGluR. This suggests that some outward current opposes inward IGluR. The IGluR inhibition displayed a U-shaped voltage-dependence with a minimal inhibition around the resting membrane potential, suggesting that simple shunting effects or deactivation of Ih cannot explain the U-shaped voltage-dependence. Confocal imaging of Na+ revealed that GluR activation caused an accumulation of Na+ in the microvilli, which can cause a negative shift of the reversal potential for Ih (Eh. Taken together, it was suggested that IGluR evoked in MTN neurons is opposed by a transient decrease or increase in standing inward or outward Ih, respectively, both of which can be caused by negative shifts of Eh, as consistent with the U-shaped voltage-dependence of the IGluR inhibition and the OT-IGluR generation. An electron-microscopic immunohistochemical study revealed the colocalization of HCN channels and glutamatergic synapses in microvilli of MTN neurons, which would provide a morphological basis for the functional interaction between HCN and GluR channels. Mathematical modeling eliminated the possibilities of the involvements of Ih deactivation and/or shunting effect and supported the negative shift of Eh which causes the U-shaped voltage-dependent inhibition of IGluR.

Submillimeter Monitoring of the HCN Molecule in Fragment C of the Split Comet 73P/Schwassmann-Wachmann 3

Science.gov (United States)

Drahus, Michal; Kueppers, M.; Jarchow, C.; Paganini, L.; Hartogh, P.; Villanueva, G. L.

2007-10-01

Comet 73P/Schwassmann-Wachmann 3 is a member of the Jupiter family which broke up into several fragments in 1995. After the unfavourable return in 2000/2001, the comet passed very close to the Earth in 2006, with the perigee distance below 0.1 AU. Simultaneously, it was well situated on the sky, which resulted in several observing campaigns. We observed this comet using the SMT facility at the Mt. Graham International Observatory in Arizona. In particular, on 5 nights between 10 and 22 May 2006 the HCN molecule in fragment C was spectroscopically monitored, through the J(3-2) and J(4-3) transitions. Using a simplified model, we found the expansion velocity of the HCN coma to be equal to 0.8 ± 0.1 km/s, what is a typical value for a comet at heliocentric distance r = 1 AU. We also reconstructed the production rates Q of this molecule, finding Q(r=1AU) = 2.7 ± 0.1 × 1025 molec/s. Our result is consistent with most of the other estimates, including the CN production rate. Furthermore, taking advantage of the fairly small beam sizes during our campaign (ranging from 600 km to 1200 km in radius), we detected short-term variability of the production rate, presumably stimulated by the nucleus rotation. Although our analysis did not yield a unique rotation period, we found a limited number of possible solutions. We will discuss them in detail along with a comparison with other period claims, and propose a possible scenario that links most of the periodicities reported so far for this comet. The SMT is operated by the Arizona Radio Observatory (ARO), Steward Observatory, University of Arizona.

Kir2.1 channels set two levels of resting membrane potential with inward rectification.

Science.gov (United States)

Chen, Kuihao; Zuo, Dongchuan; Liu, Zheng; Chen, Haijun

2018-04-01

Strong inward rectifier K + channels (Kir2.1) mediate background K + currents primarily responsible for maintenance of resting membrane potential. Multiple types of cells exhibit two levels of resting membrane potential. Kir2.1 and K2P1 currents counterbalance, partially accounting for the phenomenon of human cardiomyocytes in subphysiological extracellular K + concentrations or pathological hypokalemic conditions. The mechanism of how Kir2.1 channels contribute to the two levels of resting membrane potential in different types of cells is not well understood. Here we test the hypothesis that Kir2.1 channels set two levels of resting membrane potential with inward rectification. Under hypokalemic conditions, Kir2.1 currents counterbalance HCN2 or HCN4 cation currents in CHO cells that heterologously express both channels, generating N-shaped current-voltage relationships that cross the voltage axis three times and reconstituting two levels of resting membrane potential. Blockade of HCN channels eliminated the phenomenon in K2P1-deficient Kir2.1-expressing human cardiomyocytes derived from induced pluripotent stem cells or CHO cells expressing both Kir2.1 and HCN2 channels. Weakly inward rectifier Kir4.1 or inward rectification-deficient Kir2.1•E224G mutant channels do not set such two levels of resting membrane potential when co-expressed with HCN2 channels in CHO cells or when overexpressed in human cardiomyocytes derived from induced pluripotent stem cells. These findings demonstrate a common mechanism that Kir2.1 channels set two levels of resting membrane potential with inward rectification by balancing inward currents through different cation channels such as hyperpolarization-activated HCN channels or hypokalemia-induced K2P1 leak channels.

Fundamental role for the KCNE4 ancillary subunit in Kv7.4 regulation of arterial tone

DEFF Research Database (Denmark)

Jepps, Thomas A; Carr, Georgina; Lundegaard, Pia R

2015-01-01

tone by Kv7 channels. In HEK cells expressing Kv7.4, co-expression of KCNE4 increased the membrane expression of Kv7.4 and significantly altered Kv7.4 current properties. Quantitative PCR analysis of different rat arteries found that the KCNE4 isoform predominated and proximity ligation experiments...... leads to reduced Kv7.4 membrane abundance, a depolarized membrane potential and an augmented response to vasoconstrictors. KCNE4 is a key regulator of the function and expression of Kv7.4 in vascular smooth muscle. ABSTRACT: The KCNE ancillary subunits (KCNE1-5) significantly alter the expression...... to reduced Kv7.4 membrane abundance, a depolarized membrane potential and an augmented response to vasoconstrictors. The present study is the first to demonstrate an integral role of KCNE4 in regulating the function and expression of Kv7.4 in vascular smooth muscle....

Kcne2 deletion impairs insulin secretion and causes type 2 diabetes mellitus.

Science.gov (United States)

Lee, Soo Min; Baik, Jasmine; Nguyen, Dara; Nguyen, Victoria; Liu, Shiwei; Hu, Zhaoyang; Abbott, Geoffrey W

2017-06-01

Type 2 diabetes mellitus (T2DM) represents a rapidly increasing threat to global public health. T2DM arises largely from obesity, poor diet, and lack of exercise, but it also involves genetic predisposition. Here we report that the KCNE2 potassium channel transmembrane regulatory subunit is expressed in human and mouse pancreatic β cells. Kcne2 deletion in mice impaired glucose tolerance as early as 5 wk of age in pups fed a Western diet, ultimately causing diabetes. In adult mice fed normal chow, skeletal muscle expression of insulin receptor β and insulin receptor substrate 1 were down-regulated 2-fold by Kcne2 deletion, characteristic of T2DM. Kcne2 deletion also caused extensive pancreatic transcriptome changes consistent with facets of T2DM, including endoplasmic reticulum stress, inflammation, and hyperproliferation. Kcne2 deletion impaired β-cell insulin secretion in vitro up to 8-fold and diminished β-cell peak outward K + current at positive membrane potentials, but also left-shifted its voltage dependence and slowed inactivation. Interestingly, we also observed an aging-dependent reduction in β-cell outward currents in both Kcne2 +/+ and Kcne2 - / - mice. Our results demonstrate that KCNE2 is required for normal β-cell electrical activity and insulin secretion, and that Kcne2 deletion causes T2DM. KCNE2 may regulate multiple K + channels in β cells, including the T2DM-linked KCNQ1 potassium channel α subunit.-Lee, S. M., Baik, J., Nguyen, D., Nguyen, V., Liu, S., Hu, Z., Abbott, G. W. Kcne2 deletion impairs insulin secretion and causes type 2 diabetes mellitus. © FASEB.

FORMATION OF N{sub 3}, CH{sub 3}, HCN, AND HNC FROM THE FAR-UV PHOTOLYSIS OF CH{sub 4} IN NITROGEN ICE

Energy Technology Data Exchange (ETDEWEB)

Lo, Jen-Iu; Chou, Sheng-Lung; Peng, Yu-Chain; Lin, Meng-Yeh; Lu, Hsiao-Chi; Cheng, Bing-Ming, E-mail: bmcheng@nsrrc.org.tw [National Synchrotron Radiation Research Center, No. 101, Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan (China)

2015-11-15

The irradiation of pure solid N{sub 2} at 3 K with far-ultraviolet light from a synchrotron produced infrared absorption lines at 1657.7, 1655.6, and 1652.4 cm{sup −1} and an ultraviolet absorption line at 272.0 nm, which are characteristic of the product N{sub 3}. The threshold wavelength at which N{sub 3} was generated was 145.6 ± 2.9 nm, corresponding to an energy of 8.52 ± 0.17 eV. The photolysis of isotopically labeled {sup 15}N{sub 2} at 3 K consistently led to the formation of {sup 15}N{sub 3} with the same threshold wavelength of 145.6 ± 2.9 nm for its formation. The photolysis of CH{sub 4} in nitrogen ice in low concentrations also led to the formation of N{sub 3}, together with CH{sub 3}, HCN, and HNC, with the same threshold wavelength of 145.6 ± 2.9 nm. These results indicate that N{sub 3} radicals may play an important role in the photochemistry of nitrogen ices in astronomical environments.

KCNE1 constrains the voltage sensor of Kv7.1 K+ channels.

Directory of Open Access Journals (Sweden)

Liora Shamgar

Full Text Available Kv7 potassium channels whose mutations cause cardiovascular and neurological disorders are members of the superfamily of voltage-gated K(+ channels, comprising a central pore enclosed by four voltage-sensing domains (VSDs and sharing a homologous S4 sensor sequence. The Kv7.1 pore-forming subunit can interact with various KCNE auxiliary subunits to form K(+ channels with very different gating behaviors. In an attempt to characterize the nature of the promiscuous gating of Kv7.1 channels, we performed a tryptophan-scanning mutagenesis of the S4 sensor and analyzed the mutation-induced perturbations in gating free energy. Perturbing the gating energetics of Kv7.1 bias most of the mutant channels towards the closed state, while fewer mutations stabilize the open state or the inactivated state. In the absence of auxiliary subunits, mutations of specific S4 residues mimic the gating phenotypes produced by co-assembly of Kv7.1 with either KCNE1 or KCNE3. Many S4 perturbations compromise the ability of KCNE1 to properly regulate Kv7.1 channel gating. The tryptophan-induced packing perturbations and cysteine engineering studies in S4 suggest that KCNE1 lodges at the inter-VSD S4-S1 interface between two adjacent subunits, a strategic location to exert its striking action on Kv7.1 gating functions.

Electron density profile reconstruction by maximum entropy method with multichannel HCN laser interferometer system on SPAC VII

International Nuclear Information System (INIS)

Kubo, S.; Narihara, K.; Tomita, Y.; Hasegawa, M.; Tsuzuki, T.; Mohri, A.

1988-01-01

A multichannel HCN laser interferometer system has been developed to investigate the plasma electron confinement properties in SPAC VII device. Maximum entropy method is applied to reconstruct the electron density profile from measured line integrated data. Particle diffusion coefficient in the peripheral region of the REB ring core spherator was obtained from the evolution of the density profile. (author)

Kcne2 deletion uncovers its crucial role in thyroid hormone biosynthesis

OpenAIRE

Roepke, Torsten K.; King, Elizabeth C.; Reyna-Neyra, Andrea; Paroder, Monika; Purtell, Kerry; Koba, Wade; Fine, Eugene; Lerner, Daniel J.; Carrasco, Nancy; Abbott, Geoffrey W.

2009-01-01

Thyroid dysfunction affects 1?4% of the population worldwide, causing defects including neurodevelopmental disorders, dwarfism and cardiac arrhythmia. Here, we show that KCNQ1 and KCNE2 form a TSH-stimulated, constitutively-active, thyrocyte K+ channel required for normal thyroid hormone biosynthesis. Targeted disruption of Kcne2 impaired thyroid iodide accumulation up to 8-fold, impaired maternal milk ejection and halved milk T4 content, causing hypothyroidism, 50% reduced litter size, dwarf...

Diagnostics of a stationary MPD-type plasma jet with a HCN laser interferometer

International Nuclear Information System (INIS)

Graser, W.; Hoffmann, P.

1975-01-01

A HCN laser interferometer of the Ashby-Jephcott type operating at a wavelength of 337 μm was used to measure spatially resolved electron densities in a stationary MPD-type plasma jet with non-LTE behavior. Experiments were performed with and without superimposed magnetic fields up to 0.1 T at the exit of the plasma accelerator. Electron densities were obtained within the limits of 5times10 12 and 10 15 cm -3 with an accuracy better than 10%. Within the axially symmetric expanding plasma of about 15-cm average diameter and 50-cm length the radial resolving power came to less than 1 cm. So this technique has proved to be suitable to fill a gap in the diagnostics of stationary magnetized plasmas in the mean range of electron densities. (auth)

KCNQ1 channel modulation by KCNE proteins via the voltage-sensing domain.

Science.gov (United States)

Nakajo, Koichi; Kubo, Yoshihiro

2015-06-15

The gating of the KCNQ1 potassium channel is drastically regulated by auxiliary subunit KCNE proteins. KCNE1, for example, slows the activation kinetics of KCNQ1 by two orders of magnitude. Like other voltage-gated ion channels, the opening of KCNQ1 is regulated by the voltage-sensing domain (VSD; S1-S4 segments). Although it has been known that KCNE proteins interact with KCNQ1 via the pore domain, some recent reports suggest that the VSD movement may be altered by KCNE. The altered VSD movement of KCNQ1 by KCNE proteins has been examined by site-directed mutagenesis, the scanning cysteine accessibility method (SCAM), voltage clamp fluorometry (VCF) and gating charge measurements. These accumulated data support the idea that KCNE proteins interact with the VSDs of KCNQ1 and modulate the gating of the KCNQ1 channel. In this review, we will summarize recent findings and current views of the KCNQ1 modulation by KCNE via the VSD. In this context, we discuss our recent findings that KCNE1 may alter physical interactions between the S4 segment (VSD) and the S5 segment (pore domain) of KCNQ1. Based on these findings from ourselves and others, we propose a hypothetical mechanism for how KCNE1 binding alters the VSD movement and the gating of the channel. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

Formation of doubly and triply bonded unsaturated compounds HCN, HNC, and CH2NH via N + CH4 low-temperature solid state reaction: from molecular clouds to solar system objects

Science.gov (United States)

Mencos, Alejandro; Krim, Lahouari

2018-06-01

We show in the current study carried out in solid phase at cryogenic temperatures that methane (CH4) ice exposed to nitrogen atoms is a source of two acids HCN, HNC, and their corresponding hydrogenated unsaturated species CH2NH, in addition to CH3, C2H6, CN-, and three nitrogen hydrides NH, NH2, and NH3. The solid state N + CH4 reaction taken in the ground state seems to be strongly temperature dependent. While at temperatures lower than 10 K only CH3, NH, NH2, and NH3 species formation is promoted due to CH bond dissociation and NH bond formation, stable compounds with CN bonds are formed at temperatures ranged between 10 and 40 K. Many of these reaction products, resulting from CH4 + N reaction, have already been observed in N2-rich regions such as the atmospheres of Titan, Kuiper belt objects, and molecular clouds of the interstellar medium. Our results show the power of the solid state N-atom chemistry in the transformation of simple astrochemical relevant species, such as CH4 molecules and N atoms into complex organic molecules which are also potentially prebiotic species.

Competition between abstraction and exchange channels in H + HCN reaction: Full-dimensional quantum dynamics

Energy Technology Data Exchange (ETDEWEB)

Jiang, Bin; Guo, Hua, E-mail: hguo@unm.edu [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

2013-12-14

Dynamics of the title reaction is investigated on an ab initio based potential energy surface using a full-dimensional quantum wave packet method within the centrifugal sudden approximation. It is shown that the reaction between H and HCN leads to both the hydrogen exchange and hydrogen abstraction channels. The exchange channel has a lower threshold and larger cross section than the abstraction channel. It also has more oscillations due apparently to quantum resonances. Both channels are affected by long-lived resonances supported by potential wells. Comparison with experimental cross sections indicates underestimation of the abstraction barrier height.

Formation of 1,2-diaminomaleodinitrile crystals in radiolyzed solid hydrocyanic acid

International Nuclear Information System (INIS)

Mozhaev, P.S.; Kichigina, G.A.; Aliev, Z.G.; Kiryukhin, D.P.; Atovmyan, L.O.; Barkalov, I.M.

1994-01-01

Hydrocyanic molecules, HCN, are widely found in various extraterrestrial objects and have come to be regarded as the building blocks of chemical evolution, because they convert directly to more complex organic compounds, such as amino acids, nucleotides, and proteins. While observing the low-temperature conversion of radiolyzed solid HCN, the authors noted the formation of an amorphous polymer and the nucleation and growth of needle shaped crystals. The crystals were studied by X-ray diffraction methods and believed to be formed by 1,2-diaminomaleodinitrile, a tetramer of HCN, arising by recombination of aminocyanocarbene diradicals. Cobalt 60 was used as the radiation source, preirradiating with a 800 kGy dose a solid HCN sample at 77K

KCNE4 is an inhibitory subunit to Kv1.1 and Kv1.3 potassium channels

DEFF Research Database (Denmark)

Grunnet, Morten; Rasmussen, Hannne B; Hay-Schmidt, Anders

2003-01-01

is detected in the heart and in five different parts of the brain. Having the broad distribution of Kv1 channels in mind, the demonstrated inhibitory property of KCNE4-subunits could locally and/or transiently have a dramatic influence on cellular excitability and on setting resting membrane potentials....

The influence of zinc hydroxystannate on reducing toxic gases (CO, NO{sub x} and HCN) generation and fire hazards of thermoplastic polyurethane composites

Energy Technology Data Exchange (ETDEWEB)

Wang, Bibo; Sheng, Haibo [State Key Laboratory of Fire Science, University of Science and Technology of China, Anhui 230026 (China); Shi, Yongqian [State Key Laboratory of Fire Science, University of Science and Technology of China, Anhui 230026 (China); Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, Jiangsu, Suzhou 215123 (China); Song, Lei [State Key Laboratory of Fire Science, University of Science and Technology of China, Anhui 230026 (China); Zhang, Yan [State Key Laboratory of Fire Science, University of Science and Technology of China, Anhui 230026 (China); Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, Jiangsu, Suzhou 215123 (China); Hu, Yuan, E-mail: yuanhu@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China, Anhui 230026 (China); Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, Jiangsu, Suzhou 215123 (China); Hu, Weizhao, E-mail: hwz1988@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China, Anhui 230026 (China)

2016-08-15

Highlights: • The ZnHS could significantly enhance the mechanical properties of the TPU composites. • ZnHS has excellent smoke suppression and reduction the HRR for TPU composites. • ZnHS shows significant decrease in CO, HCN, NO{sub x} for TPU composites. • These improvements are due to charring and catalytic degradation the toxic gases. - Abstract: A uniform zinc hydroxystannate (ZnHS) microcube was synthesized to reduce toxicity and fire hazards of thermoplastic polyurethane (TPU) composites using ammonium polyphosphate as a flame retardant agent. The structure, morphology and thermal properties of ZnHS were characterized by X-ray diffraction, transmission electron microscopy and thermogravimetric analysis, respectively. Smoke suppression properties and synergistic flame retardant effect of ZnHS on flame retardant TPU composites were intensively investigated by smoke density test, cone calorimeter test, and thermalgravimetric analysis. Thermogravimetric analysis/infrared spectrometry and tube furnace were employed to evaluate the toxic gases (CO, NO{sub x} and HCN) of TPU composites. The incorporation of ZnHS into TPU matrix effectively improved the fire safety and restrained the smoke density, which is attributed to that the char residue catalyzed by ZnHS enhanced barrier effect that reduced peak heat release rate, total heat release, smoke particles and organic volatiles during combustion. Furthermore, the ZnHS synergist demonstrated high efficiency in catalytic degradation of the toxic gases, which obviously decreased total volatiled product and toxic volatiles evolved, such as the CO, HCN and NO{sub x}, indicating suppressed toxicity of the TPU composites.

A size upper limit and position for the HCN maser in CIT 6

International Nuclear Information System (INIS)

Carlstrom, J.E.; Welch, W.J.; Goldsmith, P.F.; Lis, D.C.

1990-01-01

A size upper limit and position for the HCN maser in CIT 6 were determined from interferometric observations with the Hat Creek millimeter array. The maser is located at alpha(1950) = 10 h 13 m 10.942 + or - 0.012 s and delta(1950) = + 30 deg 49 arcmin 16.75 arcsec + or - 0.15, coincident with the optical image taken from the Palomar plates, within the 3 arcsec uncertainty of the latter. The size of the maser emission region is less than 0.45 arcsec, approximately 180 AU at the distance estimated for CIT 6. The small size and strong emission (40 Jy) set a lower limit to the brightness temperature of 44,000 K, further strengthening the maser interpretation. 14 refs

Phosphatidylinositol-4,5-bisphosphate is required for KCNQ1/KCNE1 channel function but not anterograde trafficking.

Directory of Open Access Journals (Sweden)

Alice A Royal

Full Text Available The slow delayed-rectifier potassium current (IKs is crucial for human cardiac action potential repolarization. The formation of IKs requires co-assembly of the KCNQ1 α-subunit and KCNE1 β-subunit, and mutations in either of these subunits can lead to hereditary long QT syndrome types 1 and 5, respectively. It is widely recognised that the KCNQ1/KCNE1 (Q1/E1 channel requires phosphatidylinositol-4,5-bisphosphate (PIP2 binding for function. We previously identified a cluster of basic residues in the proximal C-terminus of KCNQ1 that form a PIP2/phosphoinositide binding site. Upon charge neutralisation of these residues we found that the channel became more retained in the endoplasmic reticulum, which raised the possibility that channel-phosphoinositide interactions could play a role in channel trafficking. To explore this further we used a chemically induced dimerization (CID system to selectively deplete PIP2 and/or phosphatidylinositol-4-phosphate (PI(4P at the plasma membrane (PM or Golgi, and we subsequently monitored the effects on both channel trafficking and function. The depletion of PIP2 and/or PI(4P at either the PM or Golgi did not alter channel cell-surface expression levels. However, channel function was extremely sensitive to the depletion of PIP2 at the PM, which is in contrast to the response of other cardiac potassium channels tested (Kir2.1 and Kv11.1. Surprisingly, when using the CID system IKs was dramatically reduced even before dimerization was induced, highlighting limitations regarding the utility of this system when studying processes highly sensitive to PIP2 depletion. In conclusion, we identify that the Q1/E1 channel does not require PIP2 or PI(4P for anterograde trafficking, but is heavily reliant on PIP2 for channel function once at the PM.

Opposite effects of the S4-S5 linker and PIP2 on voltage-gated channel function: KCNQ1/KCNE1 and other channels

Directory of Open Access Journals (Sweden)

Frank S Choveau

2012-07-01

Full Text Available Voltage-gated potassium (Kv channels are tetramers, each subunit presenting six transmembrane segments (S1-S6, with each S1-S4 segments forming a voltage-sensing domain (VSD and the four S5-S6 forming both the conduction pathway and its gate. S4 segments control the opening of the intracellular activation gate in response to changes in membrane potential. Crystal structures of several voltage-gated ion channels in combination with biophysical and mutagenesis studies highlighted the critical role of the S4-S5 linker (S4S5L and of the S6 C-terminal part (S6T in the coupling between the VSD and the activation gate. Several mechanisms have been proposed to describe the coupling at a molecular scale. This review summarizes the mechanisms suggested for various voltage-gated ion channels, including a mechanism that we described for KCNQ1, in which S4S5L is acting like a ligand binding to S6T to stabilize the channel in a closed state. As discussed in this review, this mechanism may explain the reverse response to depolarization in HCN-like channels. As opposed to S4S5L, the phosphoinositide, phosphatidylinositol 4,5-bisphosphate (PIP2, stabilizes KCNQ1 channel in an open state. Many other ion channels (not only voltage-gated require PIP2 to function properly, confirming its crucial importance as an ion channel co-factor. This is highlighted in cases in which an altered regulation of ion channels by PIP2 leads to channelopathies, as observed for KCNQ1. This review summarizes the state of the art on the two regulatory mechanisms that are critical for KCNQ1 and other voltage-gated channels function (PIP2 and S4-S5L, and assesses their potential physiological and pathophysiological roles.

N-terminal arginines modulate plasma-membrane localization of Kv7.1/KCNE1 channel complexes.

Directory of Open Access Journals (Sweden)

Zenawit Girmatsion

Full Text Available BACKGROUND AND OBJECTIVE: The slow delayed rectifier current (I(Ks is important for cardiac action potential termination. The underlying channel is composed of Kv7.1 α-subunits and KCNE1 β-subunits. While most evidence suggests a role of KCNE1 transmembrane domain and C-terminus for the interaction, the N-terminal KCNE1 polymorphism 38G is associated with reduced I(Ks and atrial fibrillation (a human arrhythmia. Structure-function relationship of the KCNE1 N-terminus for I(Ks modulation is poorly understood and was subject of this study. METHODS: We studied N-terminal KCNE1 constructs disrupting structurally important positively charged amino-acids (arginines at positions 32, 33, 36 as well as KCNE1 constructs that modify position 38 including an N-terminal truncation mutation. Experimental procedures included molecular cloning, patch-clamp recording, protein biochemistry, real-time-PCR and confocal microscopy. RESULTS: All KCNE1 constructs physically interacted with Kv7.1. I(Ks resulting from co-expression of Kv7.1 with non-atrial fibrillation '38S' was greater than with any other construct. Ionic currents resulting from co-transfection of a KCNE1 mutant with arginine substitutions ('38G-3xA' were comparable to currents evoked from cells transfected with an N-terminally truncated KCNE1-construct ('Δ1-38'. Western-blots from plasma-membrane preparations and confocal images consistently showed a greater amount of Kv7.1 protein at the plasma-membrane in cells co-transfected with the non-atrial fibrillation KCNE1-38S than with any other construct. CONCLUSIONS: The results of our study indicate that N-terminal arginines in positions 32, 33, 36 of KCNE1 are important for reconstitution of I(Ks. Furthermore, our results hint towards a role of these N-terminal amino-acids in membrane representation of the delayed rectifier channel complex.

Sexual dimorphism and oestrogen regulation of KCNE3 expression modulates the functional properties of KCNQ1 K channels.

LENUS (Irish Health Repository)

Alzamora, Rodrigo

2012-02-01

The KCNQ1 potassium channel associates with various KCNE ancillary subunits that drastically affect channel gating and pharmacology. Co-assembly with KCNE3 produces a current with nearly instantaneous activation, some time-dependent activation at very positive potentials, a linear current-voltage relationship and a 10-fold higher sensitivity to chromanol 293B. KCNQ1:KCNE3 channels are expressed in colonic crypts and mediate basolateral K(+) recycling required for Cl(-) secretion. We have previously reported the female-specific anti-secretory effects of oestrogen via KCNQ1:KCNE3 channel inhibition in colonic crypts. This study was designed to determine whether sex and oestrogen regulate the expression and function of KCNQ1 and KCNE3 in rat distal colon. Colonic crypts were isolated from Sprague-Dawley rats and used for whole-cell patch-clamp and to extract total RNA and protein. Sheets of epithelium were used for short-circuit current recordings. KCNE1 and KCNE3 mRNA and protein abundance were significantly higher in male than female crypts. No expression of KCNE2 was found and no difference was observed in KCNQ1 expression between male and female (at oestrus) colonic crypts. Male crypts showed a 2.2-fold higher level of association of KCNQ1 and KCNE3 compared to female cells. In female colonic crypts, KCNQ1 and KCNE3 protein expression fluctuated throughout the oestrous cycle and 17beta-oestradiol (E2 10 nM) produced a rapid (<15 min) dissociation of KCNQ1 and KCNE3 in female crypts only. Whole-cell K(+) currents showed a linear current-voltage relationship in male crypts, while K(+) currents in colonic crypts isolated from females displayed voltage-dependent outward rectification. Currents in isolated male crypts and epithelial sheets were 10-fold more sensitive to specific KCNQ1 inhibitors, such as chromanol 293B and HMR-1556, than in female. The effect of E2 on K(+) currents mediated by KCNQ1 with or without different beta-subunits was assayed from current

KCNE5 induces time- and voltage-dependent modulation of the KCNQ1 current

DEFF Research Database (Denmark)

Angelo, Kamilla; Jespersen, Thomas; Grunnet, Morten

2002-01-01

The function of the KCNE5 (KCNE1-like) protein has not previously been described. Here we show that KCNE5 induces both a time- and voltage-dependent modulation of the KCNQ1 current. Interaction of the KCNQ1 channel with KCNE5 shifted the voltage activation curve of KCNQ1 by more than 140 mV in th...... the I(Ks) current in certain parts of the mammalian heart....

Data processing with PC-9801 micro-computer for HCN laser scattering experiments

International Nuclear Information System (INIS)

Iwasaki, T.; Okajima, S.; Kawahata, K.; Tetsuka, T.; Fujita, J.

1986-09-01

In order to process the data of HCN laser scattering experiments, a micro-computer software has been developed and applied to the measurements of density fluctuations in the JIPP T-IIU tokamak plasma. The data processing system consists of a spectrum analyzer, SM-2100A Signal Analyzer (IWATSU ELECTRIC CO., LTD.), PC-9801m3 micro-computer, a CRT-display and a dot-printer. The output signals from the spectrum analyzer are A/D converted, and stored on a mini-floppy-disk equipped to the signal analyzer. The software to process the data is composed of system-programs and several user-programs. The real time data processing is carried out for every shot of plasma at 4 minutes interval by the micro-computer connected with the signal analyzer through a GP-IB interface. The time evolutions of the frequency spectrum of the density fluctuations are displayed on the CRT attached to the micro-computer and printed out on a printer-sheet. In the case of the data processing after experiments, the data stored on the floppy-disk of the signal analyzer are read out by using a floppy-disk unit attached to the micro-computer. After computation with the user-programs, the results, such as monitored signal, frequency spectra, wave number spectra and the time evolutions of the spectrum, are displayed and printed out. In this technical report, the system, the software and the directions for use are described. (author)

Qualification of a Multi-Channel Infrared Laser Absorption Spectrometer for Monitoring CO, HCl, HCN, HF, and CO2 Aboard Manned Spacecraft

Science.gov (United States)

Briggs, Ryan M.; Frez, Clifford; Forouhar, Siamak; May, Randy D.; Meyer, Marit E.; Kulis, Michael J.; Berger, Gordon M.

2015-01-01

Monitoring of specific combustion products can provide early-warning detection of accidental fires aboard manned spacecraft and also identify the source and severity of combustion events. Furthermore, quantitative in situ measurements are important for gauging levels of exposure to hazardous gases, particularly on long-duration missions where analysis of returned samples becomes impractical. Absorption spectroscopy using tunable laser sources in the 2 to 5 micrometer wavelength range enables accurate, unambiguous detection of CO, HCl, HCN, HF, and CO2, which are produced in varying amounts through the heating of electrical components and packaging materials commonly used aboard spacecraft. Here, we report on calibration and testing of a five-channel laser absorption spectrometer designed to accurately monitor ambient gas-phase concentrations of these five compounds, with low-level detection limits based on the Spacecraft Maximum Allowable Concentrations. The instrument employs a two-pass absorption cell with a total optical pathlength of 50 cm and a dedicated infrared semiconductor laser source for each target gas. We present results from testing the five-channel sensor in the presence of trace concentrations of the target compounds that were introduced using both gas sources and oxidative pyrolysis (non-flaming combustion) of solid material mixtures.

Unconventional hydrogen bonding to organic ions in the gas phase: Stepwise association of hydrogen cyanide with the pyridine and pyrimidine radical cations and protonated pyridine

Energy Technology Data Exchange (ETDEWEB)

Hamid, Ahmed M.; El-Shall, M. Samy, E-mail: mselshal@vcu.edu [Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Hilal, Rifaat; Elroby, Shaaban; Aziz, Saadullah G. [Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

2014-08-07

Equilibrium thermochemical measurements using the ion mobility drift cell technique have been utilized to investigate the binding energies and entropy changes for the stepwise association of HCN molecules with the pyridine and pyrimidine radical cations forming the C{sub 5}H{sub 5}N{sup +·}(HCN){sub n} and C{sub 4}H{sub 4}N{sub 2}{sup +·}(HCN){sub n} clusters, respectively, with n = 1–4. For comparison, the binding of 1–4 HCN molecules to the protonated pyridine C{sub 5}H{sub 5}NH{sup +}(HCN){sub n} has also been investigated. The binding energies of HCN to the pyridine and pyrimidine radical cations are nearly equal (11.4 and 12.0 kcal/mol, respectively) but weaker than the HCN binding to the protonated pyridine (14.0 kcal/mol). The pyridine and pyrimidine radical cations form unconventional carbon-based ionic hydrogen bonds with HCN (CH{sup δ+}⋯NCH). Protonated pyridine forms a stronger ionic hydrogen bond with HCN (NH{sup +}⋯NCH) which can be extended to a linear chain with the clustering of additional HCN molecules (NH{sup +}⋯NCH··NCH⋯NCH) leading to a rapid decrease in the bond strength as the length of the chain increases. The lowest energy structures of the pyridine and pyrimidine radical cation clusters containing 3-4 HCN molecules show a strong tendency for the internal solvation of the radical cation by the HCN molecules where bifurcated structures involving multiple hydrogen bonding sites with the ring hydrogen atoms are formed. The unconventional H-bonds (CH{sup δ+}⋯NCH) formed between the pyridine or the pyrimidine radical cations and HCN molecules (11–12 kcal/mol) are stronger than the similar (CH{sup δ+}⋯NCH) bonds formed between the benzene radical cation and HCN molecules (9 kcal/mol) indicating that the CH{sup δ+} centers in the pyridine and pyrimidine radical cations have more effective charges than in the benzene radical cation.

Ex situ generation of stoichiometric HCN and its application in the Pd-catalysed cyanation of aryl bromides: evidence for a transmetallation step between two oxidative addition Pd-complexes.

Science.gov (United States)

Kristensen, Steffan K; Eikeland, Espen Z; Taarning, Esben; Lindhardt, Anders T; Skrydstrup, Troels

2017-12-01

A protocol for the Pd-catalysed cyanation of aryl bromides using near stoichiometric and gaseous hydrogen cyanide is reported for the first time. A two-chamber reactor was adopted for the safe liberation of ex situ generated HCN in a closed environment, which proved highly efficient in the Ni-catalysed hydrocyanation as the test reaction. Subsequently, this setup was exploited for converting a range of aryl and heteroaryl bromides (28 examples) directly into the corresponding benzonitriles in high yields, without the need for cyanide salts. Cyanation was achieved employing the Pd(0) precatalyst, P( t Bu) 3 -Pd-G3 and a weak base, potassium acetate, in a dioxane-water solvent mixture. The methodology was also suitable for the synthesis of 13 C-labelled benzonitriles with ex situ generated 13 C-hydrogen cyanide. Stoichiometric studies with the metal complexes were undertaken to delineate the mechanism for this catalytic transformation. Treatment of Pd(P( t Bu) 3 ) 2 with H 13 CN in THF provided two Pd-hydride complexes, (P( t Bu) 3 ) 2 Pd(H)( 13 CN), and [(P( t Bu) 3 )Pd(H)] 2 Pd( 13 CN) 4 , both of which were isolated and characterised by NMR spectroscopy and X-ray crystal structure analysis. When the same reaction was performed in a THF : water mixture in the presence of KOAc, only (P( t Bu) 3 ) 2 Pd(H)( 13 CN) was formed. Subjection of this cyano hydride metal complex with the oxidative addition complex (P( t Bu) 3 )Pd(Ph)(Br) in a 1 : 1 ratio in THF led to a transmetallation step with the formation of (P( t Bu) 3 ) 2 Pd(H)(Br) and 13 C-benzonitrile from a reductive elimination step. These experiments suggest the possibility of a catalytic cycle involving initially the formation of two Pd(ii)-species from the oxidative addition of L n Pd(0) into HCN and an aryl bromide followed by a transmetallation step to L n Pd(Ar)(CN) and L n Pd(H)(Br), which both reductively eliminate, the latter in the presence of KOAc, to generate the benzonitrile and L n Pd(0).

Structural Changes and Lack of HCN1 Channels in the Binaural Auditory Brainstem of the Naked Mole-Rat (Heterocephalus glaber).

Science.gov (United States)

Gessele, Nikodemus; Garcia-Pino, Elisabet; Omerbašić, Damir; Park, Thomas J; Koch, Ursula

2016-01-01

Naked mole-rats (Heterocephalus glaber) live in large eu-social, underground colonies in narrow burrows and are exposed to a large repertoire of communication signals but negligible binaural sound localization cues, such as interaural time and intensity differences. We therefore asked whether monaural and binaural auditory brainstem nuclei in the naked mole-rat are differentially adjusted to this acoustic environment. Using antibody stainings against excitatory and inhibitory presynaptic structures, namely the vesicular glutamate transporter VGluT1 and the glycine transporter GlyT2 we identified all major auditory brainstem nuclei except the superior paraolivary nucleus in these animals. Naked mole-rats possess a well structured medial superior olive, with a similar synaptic arrangement to interaural-time-difference encoding animals. The neighboring lateral superior olive, which analyzes interaural intensity differences, is large and elongated, whereas the medial nucleus of the trapezoid body, which provides the contralateral inhibitory input to these binaural nuclei, is reduced in size. In contrast, the cochlear nucleus, the nuclei of the lateral lemniscus and the inferior colliculus are not considerably different when compared to other rodent species. Most interestingly, binaural auditory brainstem nuclei lack the membrane-bound hyperpolarization-activated channel HCN1, a voltage-gated ion channel that greatly contributes to the fast integration times in binaural nuclei of the superior olivary complex in other species. This suggests substantially lengthened membrane time constants and thus prolonged temporal integration of inputs in binaural auditory brainstem neurons and might be linked to the severely degenerated sound localization abilities in these animals.

Structural Changes and Lack of HCN1 Channels in the Binaural Auditory Brainstem of the Naked Mole-Rat (Heterocephalus glaber.

Directory of Open Access Journals (Sweden)

Nikodemus Gessele

Full Text Available Naked mole-rats (Heterocephalus glaber live in large eu-social, underground colonies in narrow burrows and are exposed to a large repertoire of communication signals but negligible binaural sound localization cues, such as interaural time and intensity differences. We therefore asked whether monaural and binaural auditory brainstem nuclei in the naked mole-rat are differentially adjusted to this acoustic environment. Using antibody stainings against excitatory and inhibitory presynaptic structures, namely the vesicular glutamate transporter VGluT1 and the glycine transporter GlyT2 we identified all major auditory brainstem nuclei except the superior paraolivary nucleus in these animals. Naked mole-rats possess a well structured medial superior olive, with a similar synaptic arrangement to interaural-time-difference encoding animals. The neighboring lateral superior olive, which analyzes interaural intensity differences, is large and elongated, whereas the medial nucleus of the trapezoid body, which provides the contralateral inhibitory input to these binaural nuclei, is reduced in size. In contrast, the cochlear nucleus, the nuclei of the lateral lemniscus and the inferior colliculus are not considerably different when compared to other rodent species. Most interestingly, binaural auditory brainstem nuclei lack the membrane-bound hyperpolarization-activated channel HCN1, a voltage-gated ion channel that greatly contributes to the fast integration times in binaural nuclei of the superior olivary complex in other species. This suggests substantially lengthened membrane time constants and thus prolonged temporal integration of inputs in binaural auditory brainstem neurons and might be linked to the severely degenerated sound localization abilities in these animals.

ALMA OBSERVATIONS OF THE SUBMILLIMETER DENSE MOLECULAR GAS TRACERS IN THE LUMINOUS TYPE-1 ACTIVE NUCLEUS OF NGC 7469

International Nuclear Information System (INIS)

Izumi, Takuma; Kohno, Kotaro; Ikarashi, Soh; Aalto, Susanne; Doi, Akihiro; Espada, Daniel; Fathi, Kambiz; Harada, Nanase; Hsieh, Pei-Ying; Matsushita, Satoki; Hatsukade, Bunyo; Hattori, Takashi; Imanishi, Masatoshi; Iono, Daisuke; Ishizuki, Sumio; Nagai, Hiroshi; Krips, Melanie; Martín, Sergio; Meier, David S.; Nakai, Naomasa

2015-01-01

We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 1 observations of the central kiloparsec region of the luminous type 1 Seyfert galaxy NGC 7469 with unprecedented high resolution (0.″5 ×0.″4 = 165 × 132 pc) at submillimeter wavelengths. Utilizing the wide bandwidth of ALMA, we simultaneously obtained HCN(4–3), HCO + (4–3), CS(7–6), and partially CO(3–2) line maps, as well as the 860 μm continuum. The region consists of the central ∼1″ component and the surrounding starburst ring with a radius of ∼1.″5–2.″5. Several structures connect these components. Except for CO(3–2), these dense gas tracers are significantly concentrated toward the central ∼1″, suggesting their suitability to probe the nuclear regions of galaxies. Their spatial distribution resembles well those of centimeter and mid-infrared continuum emissions, but it is anticorrelated with the optical one, indicating the existence of dust-obscured star formation. The integrated intensity ratios of HCN(4–3)/HCO + (4–3) and HCN(4–3)/CS(7–6) are higher at the active galactic nucleus (AGN) position than at the starburst ring, which is consistent with our previous findings (submillimeter-HCN enhancement). However, the HCN(4–3)/HCO + (4–3) ratio at the AGN position of NGC 7469 (1.11 ± 0.06) is almost half of the corresponding value of the low-luminosity type 1 Seyfert galaxy NGC 1097 (2.0 ± 0.2), despite the more than two orders of magnitude higher X-ray luminosity of NGC 7469. But the ratio is comparable to that of the close vicinity of the AGN of NGC 1068 (∼1.5). Based on these results, we speculate that some heating mechanisms other than X-ray (e.g., mechanical heating due to an AGN jet) can contribute significantly for shaping the chemical composition in NGC 1097

ALMA OBSERVATIONS OF THE SUBMILLIMETER DENSE MOLECULAR GAS TRACERS IN THE LUMINOUS TYPE-1 ACTIVE NUCLEUS OF NGC 7469

Energy Technology Data Exchange (ETDEWEB)

Izumi, Takuma; Kohno, Kotaro; Ikarashi, Soh [Institute of Astronomy, School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Aalto, Susanne [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Observatory, SE-439 94 Onsala (Sweden); Doi, Akihiro [Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara 252-5210 (Japan); Espada, Daniel [Joint ALMA Observatory, Alonso de Córdova, 3107, Vitacura, Santiago 763-0355 (Chile); Fathi, Kambiz [Stockholm Observatory, Department of Astronomy, Stockholm University, AlbaNova Centre, SE-106 91 Stockholm (Sweden); Harada, Nanase; Hsieh, Pei-Ying; Matsushita, Satoki [Academia Sinica, Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China); Hatsukade, Bunyo; Hattori, Takashi; Imanishi, Masatoshi; Iono, Daisuke; Ishizuki, Sumio; Nagai, Hiroshi [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Krips, Melanie; Martín, Sergio [Institut de Radio Astronomie Millimétrique, 300 rue de la Piscine, Domaine Universitaire, F-38406 St. Martin d’Hères (France); Meier, David S. [Department of Physics, New Mexico Institute of Mining and Technology, 801 Leroy Place, Soccoro, NM 87801 (United States); Nakai, Naomasa, E-mail: takumaizumi@ioa.s.u-tokyo.ac.jp [Department of Physics, Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Ten-nodai, Tsukuba, Ibaraki 305-8571 (Japan); and others

2015-09-20

We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 1 observations of the central kiloparsec region of the luminous type 1 Seyfert galaxy NGC 7469 with unprecedented high resolution (0.″5 ×0.″4 = 165 × 132 pc) at submillimeter wavelengths. Utilizing the wide bandwidth of ALMA, we simultaneously obtained HCN(4–3), HCO{sup +}(4–3), CS(7–6), and partially CO(3–2) line maps, as well as the 860 μm continuum. The region consists of the central ∼1″ component and the surrounding starburst ring with a radius of ∼1.″5–2.″5. Several structures connect these components. Except for CO(3–2), these dense gas tracers are significantly concentrated toward the central ∼1″, suggesting their suitability to probe the nuclear regions of galaxies. Their spatial distribution resembles well those of centimeter and mid-infrared continuum emissions, but it is anticorrelated with the optical one, indicating the existence of dust-obscured star formation. The integrated intensity ratios of HCN(4–3)/HCO{sup +}(4–3) and HCN(4–3)/CS(7–6) are higher at the active galactic nucleus (AGN) position than at the starburst ring, which is consistent with our previous findings (submillimeter-HCN enhancement). However, the HCN(4–3)/HCO{sup +}(4–3) ratio at the AGN position of NGC 7469 (1.11 ± 0.06) is almost half of the corresponding value of the low-luminosity type 1 Seyfert galaxy NGC 1097 (2.0 ± 0.2), despite the more than two orders of magnitude higher X-ray luminosity of NGC 7469. But the ratio is comparable to that of the close vicinity of the AGN of NGC 1068 (∼1.5). Based on these results, we speculate that some heating mechanisms other than X-ray (e.g., mechanical heating due to an AGN jet) can contribute significantly for shaping the chemical composition in NGC 1097.

Development of selective catalytic oxidation (SCO) for NH{sub 3} and HCN removal from gasification gas; Selektiivisen katalyyttisen hapetusprosessin (SCO) kehittaeminen kaasutuskaasun NH{sub 3}:n ja HCN:n poistoon

Energy Technology Data Exchange (ETDEWEB)

Leppaelahti, J.; Koljonen, T.; Heiskanen, K. [VTT Energy, Espoo (Finland)

1997-10-01

In gasification, reactive nitrogen compounds (mainly NH{sub 3} and HCN) are formed from fuel nitrogen. If the gas containing NH{sub 3} is burned, a high NO{sub x} emission may be formed. The content of nitrogen compounds of the hot gasification gas could be reduced in Selective Catalytic Oxidation (SCO) process. In this process small amounts of reactive oxidisers are injected into the gas in order to convert NH{sub 3} to N{sub 2}. The utilization of SCO process together with low NO{sub x} burners in advanced gasification power stations might offer an alternative for flue gas treatment technologies like SCR (Selective Catalytic Reduction). In the earlier research, conditions were found, where oxidizers reacted selectively with ammonia in the gasification gas. Highest ammonia reduction took place in the aluminium oxide bed in the presence of NO and O{sub 2}. The aim of this study is to examine the reaction mechanism in order to be able to further evaluate the development possibilities of this kind process. The effect of composition and the amount of added oxidizer, the content of combustible gas components, space velocity, pressure and temperature will be studied. The experiments are carried out with the laboratory scale high pressure flow reactor of VTT Energy. Kinetic modelling of the experimental results is carried out in co-operation with the combustion chemistry group of Aabo Akademi. The aim of the modelling work is to bring insight to the gas-phase reactions that are important for the SCO-process. (orig.)

Molecular cloning and functional expression of the K+ channel KV7.1 and the regulatory subunit KCNE1 from equine myocardium

DEFF Research Database (Denmark)

Pedersen, Philip Juul; Thomsen, Kirsten B.; Flak, Jon B.

2017-01-01

To characterize equine KV7.1/KCNE1 currents and compare them to human KV7.1/KCNE1 currents to determine whether KV7.1/KCNE1 plays a similar role in equine and human hearts. Methods mRNA encoding KV7.1 and KCNE1 was isolated from equine hearts, sequenced, and cloned into expression vectors. The channel subunits...... were heterologously expressed in Xenopus laevis oocytes or CHO-K1 cells and characterized using voltage-clamp techniques. Results Equine KV7.1/KCNE1 expressed in CHO-K1 cells exhibited electrophysiological properties that are overall similar to the human orthologs; however, a slower deactivation...

Ground-based multiwavelength observations of comet 103P/Hartley 2

International Nuclear Information System (INIS)

Gicquel, A.; Villanueva, G. L.; Cordiner, M. A.; Milam, S. N.; Charnley, S. B.; Remijan, A. J.; Coulson, I. M.; Chuang, Y.-L.; Kuan, Y.-J.

2014-01-01

The Jupiter-family comet 103P/Hartley 2 (103P) was the target of the NASA EPOXI mission. In support of this mission, we conducted observations from radio to submillimeter wavelengths of comet 103P in the three weeks preceding the spacecraft rendezvous on UT 2010 November 4.58. This time period included the passage at perihelion and the closest approach of the comet to the Earth. Here, we report detections of HCN, H 2 CO, CS, and OH and upper limits for HNC and DCN toward 103P using the Arizona Radio Observatory Kitt Peak 12 m telescope (ARO 12 m) and submillimeter telescope (SMT), the James Clerk Maxwell Telescope (JCMT), and the Green Bank Telescope (GBT). The water production rate, Q H 2 O = (0.67-1.07) × 10 28 s –1 , was determined from the GBT OH data. From the average abundance ratios of HCN and H 2 CO relative to water (0.13 ± 0.03% and 0.14 ± 0.03%, respectively), we conclude that H 2 CO is depleted and HCN is normal with respect to typically observed cometary mixing ratios. However, the abundance ratio of HCN with water shows a large diversity with time. Using the JCMT data, we measured an upper limit for the DCN/HCN ratio <0.01. Consecutive observations of ortho-H 2 CO and para-H 2 CO on November 2 (from data obtained at the JCMT) allowed us to derive an ortho:para ratio (OPR) of ≈2.12 ± 0.59 (1σ), corresponding to T spin > 8 K (2σ).

Ground-based multiwavelength observations of comet 103P/Hartley 2

Energy Technology Data Exchange (ETDEWEB)

Gicquel, A.; Villanueva, G. L.; Cordiner, M. A. [Catholic University of America, Physics Department, 620 Michigan Avenue NE, Washington, DC (United States); Milam, S. N.; Charnley, S. B. [Goddard Center for Astrobiology, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Remijan, A. J. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Coulson, I. M. [Joint Astronomy Centre, 660 North A' ohoku Place University Park, Hilo, HI 96720 (United States); Chuang, Y.-L.; Kuan, Y.-J., E-mail: adeline.gicquel@nasa.gov, E-mail: stefanie.n.milam@nasa.gov, E-mail: geronimo.l.villanueva@nasa.gov, E-mail: steven.b.charnley@nasa.gov, E-mail: martin.a.cordiner@nasa.gov, E-mail: aremijan@nrao.edu, E-mail: i.coulson@jach.hawaii.edu, E-mail: ylchuang@std.ntnu.edu.tz, E-mail: kuan@ntnu.edu.tw [National Taiwan Normal University, 88 Sec. 4 Ting-Chou Road, Taipei 116, Taiwan (China)

2014-10-10

The Jupiter-family comet 103P/Hartley 2 (103P) was the target of the NASA EPOXI mission. In support of this mission, we conducted observations from radio to submillimeter wavelengths of comet 103P in the three weeks preceding the spacecraft rendezvous on UT 2010 November 4.58. This time period included the passage at perihelion and the closest approach of the comet to the Earth. Here, we report detections of HCN, H{sub 2}CO, CS, and OH and upper limits for HNC and DCN toward 103P using the Arizona Radio Observatory Kitt Peak 12 m telescope (ARO 12 m) and submillimeter telescope (SMT), the James Clerk Maxwell Telescope (JCMT), and the Green Bank Telescope (GBT). The water production rate, Q{sub H{sub 2O}} = (0.67-1.07) × 10{sup 28} s{sup –1}, was determined from the GBT OH data. From the average abundance ratios of HCN and H{sub 2}CO relative to water (0.13 ± 0.03% and 0.14 ± 0.03%, respectively), we conclude that H{sub 2}CO is depleted and HCN is normal with respect to typically observed cometary mixing ratios. However, the abundance ratio of HCN with water shows a large diversity with time. Using the JCMT data, we measured an upper limit for the DCN/HCN ratio <0.01. Consecutive observations of ortho-H{sub 2}CO and para-H{sub 2}CO on November 2 (from data obtained at the JCMT) allowed us to derive an ortho:para ratio (OPR) of ≈2.12 ± 0.59 (1σ), corresponding to T {sub spin} > 8 K (2σ).

ELECTRON IRRADIATION OF KUIPER BELT SURFACE ICES: TERNARY N2-CH4-CO MIXTURES AS A CASE STUDY

International Nuclear Information System (INIS)

Kim, Y. S.; Kaiser, R. I.

2012-01-01

The space weathering of icy Kuiper Belt Objects was investigated in this case study by exposing methane (CH 4 ) and carbon monoxide (CO) doped nitrogen (N 2 ) ices at 10 K to ionizing radiation in the form of energetic electrons. Online and in situ Fourier transform infrared spectroscopy was utilized to monitor the radiation-induced chemical processing of these ices. Along with isocyanic acid (HNCO), the products could be mainly derived from those formed in irradiated binary ices of the N 2 -CH 4 and CO-CH 4 systems: nitrogen-bearing products were found in the form of hydrogen cyanide (HCN), hydrogen isocyanide (HNC), diazomethane (CH 2 N 2 ), and its radical fragment (HCN 2 ); oxygen-bearing products were of acetaldehyde (CH 3 CHO), formyl radical (HCO), and formaldehyde (H 2 CO). As in the pure ices, the methyl radical (CH 3 ) and ethane (C 2 H 6 ) were also detected, as were carbon dioxide (CO 2 ) and the azide radical (N 3 ). Based on the temporal evolution of the newly formed products, kinetic reaction schemes were then developed to fit the temporal profiles of the newly formed species, resulting in numerical sets of rate constants. The current study highlights important constraints on the preferential formation of isocyanic acid (HNCO) over hydrogen cyanide (HCN) and hydrogen isocyanide (HNC), thus guiding the astrobiological and chemical evolution of those distant bodies.

Ménière's Disease: Molecular Analysis of Aquaporins 2, 3 and Potassium Channel KCNE1 Genes in Brazilian Patients.

Science.gov (United States)

Lopes, Karen de Carvalho; Sartorato, Edi Lúcia; da Silva-Costa, Sueli M; de Macedo Adamov, Nadya Soares; Ganança, Fernando Freitas

2016-09-01

Ménière's disease (MD) is a complex disease of unknown etiology characterized by a symptomatic tetrad of vertigo, hearing loss, tinnitus, and aural fullness. In addition to factors related to homeostasis of the inner ear, genetic factors have been implicated in its pathophysiology, including genes related to the transport of water and ionic composition maintenance of the endolymph, such as the aquaporin genes AQP2 and AQP3, and the potassium channel gene KCNE1. The aim of this study was to identify polymorphisms of these genes and determine their association with clinical characteristics of patients with MD. A case-control genetic association study was carried out, including 30 patients with definite Ménière's disease and 30 healthy controls. The coding regions of the target genes were amplified from blood samples by polymerase chain reaction (PCR), followed by direct sequencing. The associations of polymorphisms with clinical characteristics were analyzed with logistic regression. Five polymorphisms were identified: rs426496 in AQP2; rs591810 in AQP3; and rs1805127, rs1805128, and rs17173510 in KCNE1. After adjustment, rs426496 was significantly associated with tinnitus during the initial crisis and with altered electronystagmography, and rs1805127 was significantly associated with nephropathy. The genetic variant rs426496 in AQP2; rs591810 in AQP3 and rs1805127, rs1805128, and rs17173510, in KCNE1 were found in patients with Ménière's disease. The polymorphism rs426496, in AQP2, is associated with tinnitus at the onset of Ménière's disease and altered electronystagmography. In addition, rs1805127, in KCNE1, is associated with the presence of nephropathy.

Molecular Cloning and Functional Expression of the Equine K+ Channel KV11.1 (Ether à Go-Go-Related/KCNH2 Gene and the Regulatory Subunit KCNE2 from Equine Myocardium.

Directory of Open Access Journals (Sweden)

Philip Juul Pedersen

Full Text Available The KCNH2 and KCNE2 genes encode the cardiac voltage-gated K+ channel KV11.1 and its auxiliary β subunit KCNE2. KV11.1 is critical for repolarization of the cardiac action potential. In humans, mutations or drug therapy affecting the KV11.1 channel are associated with prolongation of the QT intervals on the ECG and increased risk of ventricular tachyarrhythmia and sudden cardiac death--conditions known as congenital or acquired Long QT syndrome (LQTS, respectively. In horses, sudden, unexplained deaths are a well-known problem. We sequenced the cDNA of the KCNH2 and KCNE2 genes using RACE and conventional PCR on mRNA purified from equine myocardial tissue. Equine KV11.1 and KCNE2 cDNA had a high homology to human genes (93 and 88%, respectively. Equine and human KV11.1 and KV11.1/KCNE2 were expressed in Xenopus laevis oocytes and investigated by two-electrode voltage-clamp. Equine KV11.1 currents were larger compared to human KV11.1, and the voltage dependence of activation was shifted to more negative values with V1/2 = -14.2±1.1 mV and -17.3±0.7, respectively. The onset of inactivation was slower for equine KV11.1 compared to the human homolog. These differences in kinetics may account for the larger amplitude of the equine current. Furthermore, the equine KV11.1 channel was susceptible to pharmacological block with terfenadine. The physiological importance of KV11.1 was investigated in equine right ventricular wedge preparations. Terfenadine prolonged action potential duration and the effect was most pronounced at slow pacing. In conclusion, these findings indicate that horses could be disposed to both congenital and acquired LQTS.

Structural basis for KCNE3 modulation of potassium recycling in epithelia.

Science.gov (United States)

Kroncke, Brett M; Van Horn, Wade D; Smith, Jarrod; Kang, CongBao; Welch, Richard C; Song, Yuanli; Nannemann, David P; Taylor, Keenan C; Sisco, Nicholas J; George, Alfred L; Meiler, Jens; Vanoye, Carlos G; Sanders, Charles R

2016-09-01

The single-span membrane protein KCNE3 modulates a variety of voltage-gated ion channels in diverse biological contexts. In epithelial cells, KCNE3 regulates the function of the KCNQ1 potassium ion (K(+)) channel to enable K(+) recycling coupled to transepithelial chloride ion (Cl(-)) secretion, a physiologically critical cellular transport process in various organs and whose malfunction causes diseases, such as cystic fibrosis (CF), cholera, and pulmonary edema. Structural, computational, biochemical, and electrophysiological studies lead to an atomically explicit integrative structural model of the KCNE3-KCNQ1 complex that explains how KCNE3 induces the constitutive activation of KCNQ1 channel activity, a crucial component in K(+) recycling. Central to this mechanism are direct interactions of KCNE3 residues at both ends of its transmembrane domain with residues on the intra- and extracellular ends of the KCNQ1 voltage-sensing domain S4 helix. These interactions appear to stabilize the activated "up" state configuration of S4, a prerequisite for full opening of the KCNQ1 channel gate. In addition, the integrative structural model was used to guide electrophysiological studies that illuminate the molecular basis for how estrogen exacerbates CF lung disease in female patients, a phenomenon known as the "CF gender gap."

KCNE1 D85N polymorphism — a sex-specific modifier in type 1 long QT syndrome?

Directory of Open Access Journals (Sweden)

Marjamaa Annukka

2011-01-01

Full Text Available Abstract Background Long QT syndrome (LQTS is an inherited ion channel disorder manifesting with prolongation of the cardiac repolarization phase and severe ventricular arrhythmias. The common KCNE1 D85N potassium channel variant prolongs QT interval by inhibiting IKs (KCNQ1 and IKr (KCNH2 currents and is therefore a suitable candidate for a modifier gene in LQTS. Methods We studied the effect of D85N on age-, sex-, and heart rate-adjusted QT-interval duration by linear regression in LQTS patients carrying the Finnish founder mutations KCNQ1 G589D (n = 492, KCNQ1 IVS7-2A>G (n = 66, KCNH2 L552S (n = 73, and KCNH2 R176W (n = 88. We also investigated the association between D85N and clinical variables reflecting the severity of the disease. Results D85N was associated with a QT prolongation by 26 ms (SE 8.6, p = 0.003 in males with KCNQ1 G589D (n = 213, but not in females with G589D (n = 279. In linear regression, the interaction between D85N genotype and sex was significant (p = 0.028. Within the KCNQ1 G589D mutation group, KCNE1 D85N carriers were more often probands of the family (p = 0.042 and were more likely to use beta blocker medication (p = 0.010 than non-carriers. The number of D85N carriers in other founder mutation groups was too small to assess its effects. Conclusions We propose that KCNE1 D85N is a sex-specific QT-interval modifier in type 1 LQTS and may also associate with increased severity of disease. Our data warrant additional studies on the role of KCNE1 D85N in other genetically homogeneous groups of LQTS patients.

Adsorption behavior of Co anchored on graphene sheets toward NO, SO2, NH3, CO and HCN molecules

International Nuclear Information System (INIS)

Tang, Yanan; Chen, Weiguang; Li, Chenggang; Pan, Lijun; Dai, Xianqi; Ma, Dongwei

2015-01-01

Graphical abstract: - Highlights: • In contrast to the pristine graphene, a vacancy defect in graphene strongly stabilizes the Co atom. • The positively charged of Co atom on graphene can regulate the stability of gas molecules. • Different gas molecules can modulate the electronic structure of Co–graphene systems. • The adsorbed NO on Co–graphene can effectively regulate the magnetic properties of systems. - Abstract: Based on the first-principles of density-functional theory (DFT), the effects of gas adsorption on the change in geometric stability, electronic structure and magnetic properties of graphene with anchored Co (Co–graphene) systems were investigated. A single Co adatom interacts much weaker with pristine graphene (Co/pri–graphene) than with the graphene containing a single vacancy (Co/SV–graphene). The Co dopant provides more electrons to the dangling bonds of carbon atom at defective site and exhibits more positive charges, which makes Co/SV–graphene less prone to be adsorbed by gas molecules in comparison to Co/pri–graphene. It is found that the electronic structure and magnetic properties of Co–graphene systems can be modulated by adsorbing gas molecules. Except the NH 3 molecule, the adsorbed NO, SO 2 , CO or HCN as electron acceptors on the Co/pri–graphene can exhibit semiconducting properties. Among the gas molecules, the strong adsorption of NO molecule can effectively regulate the magnetic properties of Co–graphene systems. Moreover, the stable configuration of Co/SV–graphene is more likely to be the gas sensor for detecting NO and SO 2 . The results validate that the reactivity of atomic-scale catalyst is supported on graphene sheets, which is expected to be potentially efficient in the gas sensors and electronic device

Spectrophotometry and organic matter on Iapetus. 1: Composition models

Science.gov (United States)

Wilson, Peter D.; Sagan, Carl

1995-01-01

Iapetus shows a greater hemispheric albedo asymmetry than any other body in the solar system. Hapke scattering theory and optical constants measured in the laboratory are used to identify possible compositions for the dark material on the leading hemisphere of Iapetus. The materials considered are poly-HCN, kerogen, Murchison organic residue, Titan tholin, ice tholin, and water ice. Three-component mixtures of these materials are modeled in intraparticle mixture of 25% poly-HCN, 10% Murchison residue, and 65% water ice is found to best fit the spectrum, albedo, and phase behavior of the dark material. The Murchison residue and/or water ice can be replaced by kerogen and ice tholin, respectively, and still produce very good fits. Areal and particle mixtures of poly-HCN, Titan tholin, and either ice tholin or Murchison residue are also possible models. Poly-HCN is a necessary component in almost all good models. The presence of poly-HCN can be further tested by high-resolution observations near 4.5 micrometers.

Characterization of KCNE1 inside Lipodisq Nanoparticles for EPR Spectroscopic Studies of Membrane Proteins.

Science.gov (United States)

Sahu, Indra D; Zhang, Rongfu; Dunagan, Megan M; Craig, Andrew F; Lorigan, Gary A

2017-06-01

EPR spectroscopic studies of membrane proteins in a physiologically relevant native membrane-bound state are extremely challenging due to the complexity observed in inhomogeneity sample preparation and dynamic motion of the spin-label. Traditionally, detergent micelles are the most widely used membrane mimetics for membrane proteins due to their smaller size and homogeneity, providing high-resolution structure analysis by solution NMR spectroscopy. However, it is often difficult to examine whether the protein structure in a micelle environment is the same as that of the respective membrane-bound state. Recently, lipodisq nanoparticles have been introduced as a potentially good membrane mimetic system for structural studies of membrane proteins. However, a detailed characterization of a spin-labeled membrane protein incorporated into lipodisq nanoparticles is still lacking. In this work, lipodisq nanoparticles were used as a membrane mimic system for probing the structural and dynamic properties of the integral membrane protein KCNE1 using site-directed spin labeling EPR spectroscopy. The characterization of spin-labeled KCNE1 incorporated into lipodisq nanoparticles was carried out using CW-EPR titration experiments for the EPR spectral line shape analysis and pulsed EPR titration experiment for the phase memory time (T m ) measurements. The CW-EPR titration experiment indicated an increase in spectral line broadening with the addition of the SMA polymer which approaches close to the rigid limit at a lipid to polymer weight ratio of 1:1, providing a clear solubilization of the protein-lipid complex. Similarly, the T m titration experiment indicated an increase in T m values with the addition of SMA polymer and approaches ∼2 μs at a lipid to polymer weight ratio of 1:2. Additionally, CW-EPR spectral line shape analysis was performed on six inside and six outside the membrane spin-label probes of KCNE1 in lipodisq nanoparticles. The results indicated significant

Experimental investigation of aminoacetonitrile formation through the Strecker synthesis in astrophysical-like conditions: reactivity of methanimine (CH2NH), ammonia (NH3), and hydrogen cyanide (HCN)

Science.gov (United States)

Danger, G.; Borget, F.; Chomat, M.; Duvernay, F.; Theulé, P.; Guillemin, J.-C.; Le Sergeant D'Hendecourt, L.; Chiavassa, T.

2011-11-01

Context. Studing chemical reactivity in astrophysical environments is an important means for improving our understanding of the origin of the organic matter in molecular clouds, in protoplanetary disks, and possibly, as a final destination, in our solar system. Laboratory simulations of the reactivity of ice analogs provide important insight into the reactivity in these environments. Here, we use these experimental simulations to investigate the Strecker synthesis leading to the formation of aminoacetonitrile in astrophysical-like conditions. The aminoacetonitrile is an interesting compound because it was detected in SgrB2, hence could be a precursor of the smallest amino acid molecule, glycine, in astrophysical environments. Aims: We present the first experimental investigation of the formation of aminoacetonitrile NH2CH2CN from the thermal processing of ices including methanimine (CH2NH), ammonia (NH3), and hydrogen cyanide (HCN) in interstellar-like conditions without VUV photons or particules. Methods: We use Fourier Transform InfraRed (FTIR) spectroscopy to monitor the ice evolution during its warming. Infrared spectroscopy and mass spectroscopy are then used to identify the aminoacetonitrile formation. Results: We demonstrate that methanimine can react with -CN during the warming of ice analogs containing at 20 K methanimine, ammonia, and [NH4+ -CN] salt. During the ice warming, this reaction leads to the formation of poly(methylene-imine) polymers. The polymer length depend on the initial ratio of mass contained in methanimine to that in the [NH4+ -CN] salt. In a methanimine excess, long polymers are formed. As the methanimine is progressively diluted in the [NH4+ -CN] salt, the polymer length decreases until the aminoacetonitrile formation at 135 K. Therefore, these results demonstrate that aminoacetonitrile can be formed through the second step of the Strecker synthesis in astrophysical-like conditions.

En Route to Destruction: the Evolution in Composition of Ices in Comet D 2012 S1 (ISON) Between 1.2 and 0.34 Au from the Sun as Revealed at Infrared Wavelengths

Science.gov (United States)

Disanti, M. A.; Bonev, B. P.; Gibb, L. E.; Paganini, L.; Villanueva, G.; Mumma, M. J.; Keane, J. V.; Blake, G. A.; Dello Russo, N.; Meech, K. J.;

Metal-porphyrin interactions. V. Kinetics of cyanide addition to a water soluble iron porphyrin dimer(1)

Energy Technology Data Exchange (ETDEWEB)

Hambright, P; Rishnamurthy, M K

1975-01-01

The kinetics of cyanide addition to the water-soluble oxybridged iron dimer of tetra (p-sulophenyl) porphin indicate that HCN is the reactant. The rate law is of the form: Rate = (3.8 +- 0.2) x 10/sup 4/ (Fe dimer) (HCN)/(1 + (3.1 +- 0.3) x 10/sup 10/ (H/sup +/)) at 25/sup 0/ ..mu.. = 0.7 (NaNO/sub 3/). The cyano iron dimer dissociates into dicyano iron monomers by two pathways, one first order in (H/sup +/), and one proportional to (H/sup +/)(CN/sup -/)/sup 2/. The mechanism of this dimer reaction is compared to iron porphyrin monomer systems.

The Dense Molecular Gas and Nuclear Activity in the ULIRG IRAS 13120–5453

Energy Technology Data Exchange (ETDEWEB)

Privon, G. C.; Treister, E. [Instituto de Astrofśica, Facultad de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22 (Chile); Aalto, S.; Falstad, N.; Muller, S.; Costagliola, F. [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, SE-439 94 Onsala (Sweden); González-Alfonso, E. [Universidad de Alcalá, Departamento de Física y Matemáticas, Campus Universitario, E-28871 Alcalá de Henares, Madrid (Spain); Sliwa, K. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Armus, L. [Spitzer Science Center, California Institute of Technology, MS 220-6, Pasadena, CA, 91125 (United States); Evans, A. S. [Department of Astronomy, University of Virginia, Charlottesville, VA 22903 (United States); Garcia-Burillo, S. [Observatorio de Madrid, OAN-IGN, Alfonso XII, 3, E-28014-Madrid (Spain); Izumi, T. [Institute of Astronomy, School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Sakamoto, K. [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, 10617, Taipei, Taiwan (China); Werf, P. van der [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Chu, J. K. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)

2017-02-01

We present new Atacama Large Millimeter/submillimeter Array Band 7 (∼340 GHz) observations of the dense gas tracers HCN, HCO{sup +}, and CS in the local, single-nucleus, ultraluminous infrared galaxy IRAS 13120–5453. We find centrally enhanced HCN (4–3) emission, relative to HCO{sup +} (4–3), but do not find evidence for radiative pumping of HCN. Considering the size of the starburst (0.5 kpc) and the estimated supernovae rate of ∼1.2 yr{sup −1}, the high HCN/HCO{sup +} ratio can be explained by an enhanced HCN abundance as a result of mechanical heating by the supernovae, though the active galactic nucleus and winds may also contribute additional mechanical heating. The starburst size implies a high Σ{sub IR} of 4.7 × 10{sup 12} L {sub ⊙} kpc{sup −2}, slightly below predictions of radiation-pressure limited starbursts. The HCN line profile has low-level wings, which we tentatively interpret as evidence for outflowing dense molecular gas. However, the dense molecular outflow seen in the HCN line wings is unlikely to escape the Galaxy and is destined to return to the nucleus and fuel future star formation. We also present modeling of Herschel observations of the H{sub 2}O lines and find a nuclear dust temperature of ∼40 K. IRAS 13120–5453 has a lower dust temperature and Σ{sub IR} than is inferred for the systems termed “compact obscured nuclei (CONs)” (such as Arp 220 and Mrk 231). If IRAS 13120–5453 has undergone a CON phase, we are likely witnessing it at a time when the feedback has already inflated the nuclear ISM and diluted star formation in the starburst/active galactic nucleus core.

Adsorption behavior of Co anchored on graphene sheets toward NO, SO{sub 2}, NH{sub 3}, CO and HCN molecules

Energy Technology Data Exchange (ETDEWEB)

Tang, Yanan, E-mail: yntang2010@hotmail.com [College of Physics and Electronic Engineering, Zhengzhou Normal University, Zhengzhou, Henan 450044 (China); Quantum Materials Research Center, Zhengzhou Normal University, Henan 450044 (China); Chen, Weiguang; Li, Chenggang; Pan, Lijun [College of Physics and Electronic Engineering, Zhengzhou Normal University, Zhengzhou, Henan 450044 (China); Quantum Materials Research Center, Zhengzhou Normal University, Henan 450044 (China); Dai, Xianqi, E-mail: xqdai@henannu.edu.cn [College of Physics and Electronic Engineering, Zhengzhou Normal University, Zhengzhou, Henan 450044 (China); Quantum Materials Research Center, Zhengzhou Normal University, Henan 450044 (China); Ma, Dongwei [College of Physics and Electrical Engineering, Anyang Normal University, Anyang, Henan 455000 (China)

2015-07-01

Graphical abstract: - Highlights: • In contrast to the pristine graphene, a vacancy defect in graphene strongly stabilizes the Co atom. • The positively charged of Co atom on graphene can regulate the stability of gas molecules. • Different gas molecules can modulate the electronic structure of Co–graphene systems. • The adsorbed NO on Co–graphene can effectively regulate the magnetic properties of systems. - Abstract: Based on the first-principles of density-functional theory (DFT), the effects of gas adsorption on the change in geometric stability, electronic structure and magnetic properties of graphene with anchored Co (Co–graphene) systems were investigated. A single Co adatom interacts much weaker with pristine graphene (Co/pri–graphene) than with the graphene containing a single vacancy (Co/SV–graphene). The Co dopant provides more electrons to the dangling bonds of carbon atom at defective site and exhibits more positive charges, which makes Co/SV–graphene less prone to be adsorbed by gas molecules in comparison to Co/pri–graphene. It is found that the electronic structure and magnetic properties of Co–graphene systems can be modulated by adsorbing gas molecules. Except the NH{sub 3} molecule, the adsorbed NO, SO{sub 2}, CO or HCN as electron acceptors on the Co/pri–graphene can exhibit semiconducting properties. Among the gas molecules, the strong adsorption of NO molecule can effectively regulate the magnetic properties of Co–graphene systems. Moreover, the stable configuration of Co/SV–graphene is more likely to be the gas sensor for detecting NO and SO{sub 2}. The results validate that the reactivity of atomic-scale catalyst is supported on graphene sheets, which is expected to be potentially efficient in the gas sensors and electronic device.

The oxidative disposition of potassium cyanide in mice

International Nuclear Information System (INIS)

Johnson, J.D.; Isom, G.E.

1986-01-01

The role of oxidative metabolism in the disposition of potassium cyanide (KCN), was investigated in mice administered KCN (4.6 mg/kg, s.c.) containing 4.5 uCi ( 14 C)KCN. The expired pulmonary metabolites, ( 14 C) hydrocyanic acid (HCN) and 14 CO 2 , were collected and analyzed. Approximately 1% and 2% of the KCN dose was expired as ( 14 C)HCN and 14 CO 2 , respectively. Expiration of the pulmonary metabolites was decreased following pretreatment with sodium nitrite, sodium thiosulfate, oxygen, or a combination of cyanide antidotes. Treatment with hydrogen peroxide lowered the amount of ( 14 C)HCN expired and did not alter the expiration of 14 CO 2 . Treatment with 3-amino-1,2,4-triazole (catalase inhibitor), superoxide dismutase, or diethyldithiocarbamic acid (superoxide dismutase inhibitor) did not change the amount of ( 14 C)HCN expired. However, superoxide dismutase significantly increased the amount of 14 CO 2 expired, whereas diethyldithiocarbamic acid decreased 14 CO 2 expiration. The results from these studies suggest that in vivo cyanide can be oxidized to CO 2 and treatment with agents that alter the availability of endogenous superoxide and/or hydrogen peroxide can alter the rate of cyanide oxidation. (author)

Dual Regulation of Voltage-Sensitive Ion Channels by PIP2

Directory of Open Access Journals (Sweden)

Aldo A Rodríguez Menchaca

2012-09-01

Full Text Available Over the past 16 years, there has been an impressive number of ion channels shown to be sensitive to the major phosphoinositide in the plasma membrane, phosphatidilinositol 4,5-bisphosphate (PIP2. Among them are voltage-gated channels, which are crucial for both neuronal and cardiac excitability. Voltage-gated calcium (Cav channels were shown to be regulated bidirectionally by PIP2. On one hand, PIP2 stabilized their activity by reducing current rundown but on the other hand it produced a voltage-dependent inhibition by shifting the activation curve to more positive voltages. For voltage-gated potassium (Kv channels PIP2 was first shown to prevent N-type inactivation. Careful examination of the effects of PIP2 on the activation mechanism of Kv1.2 has shown a similar bidirectional regulation as in the Cav channels. The two effects could be distinguished kinetically, in terms of their sensitivities to PIP2 and by distinct molecular determinants. The rightward shift of the Kv1.2 voltage dependence implicated basic residues in the S4-S5 linker and was consistent with stabilization of the inactive state of the voltage sensor. A third type of a voltage-gated ion channel modulated by PIP2 is the hyperpolarization-activated cyclic nucleotide-gated (HCN channel. PIP2 has been shown to enhance the opening of HCN channels by shifting their voltage-dependent activation toward depolarized potentials. The sea urchin HCN channel, SpIH, showed again a PIP2-mediated bidirectional effect but in reverse order than the depolarization-activated Cav and Kv channels: a voltage-dependent potentiation, like the mammalian HCN channels, but also an inhibition of the cGMP-induced current activation. Just like the Kv1.2 channels, distinct molecular determinants underlied the PIP2 dual effects on SpIH channels. The dual regulation of these very different ion channels, all of which are voltage dependent, points to conserved mechanisms of regulation of these channels by PIP2.

A molecular toolbox for rapid generation of viral vectors to up- or down-regulate in vivo neuronal gene expression

Directory of Open Access Journals (Sweden)

Melanie D. White

2011-07-01

Full Text Available We introduce a molecular toolbox for manipulation of neuronal gene expression in vivo. The toolbox includes promoters, ion channels, optogenetic tools, fluorescent proteins and intronic artificial microRNAs. The components are easily assembled into adeno-associated virus (AAV or lentivirus vectors using recombination cloning. We demonstrate assembly of toolbox components into lentivirus and AAV vectors and use these vectors for in vivo expression of inwardly rectifying potassium channels (Kir2.1, Kir3.1 and Kir3.2 and an artificial microRNA targeted against the ion channel HCN1 (HCN1 miR. We show that AAV assembled to express HCN1 miR produces efficacious and specific in vivo knockdown of HCN1 channels. Comparison of in vivo viral transduction using HCN1 miR with mice containing a germ line deletion of HCN1 reveals similar physiological phenotypes in cerebellar Purkinje cells. The easy assembly and re-usability of the toolbox components, together with the ability to up- or down-regulate neuronal gene expression in vivo, may be useful for applications in many areas of neuroscience.

Broadening of spectral lines of CO2, N2O , H2CO, HCN, and H2S by pressure of gases dominant in planetary atmospheres (H2, He and CO2)

Science.gov (United States)

Samuels, Shanelle; Gordon, Iouli; Tan, Yan

2018-01-01

HITRAN1,2 is a compilation of spectroscopic parameters that a variety of computer codes use to predict and simulate the transmission and emission of light in planetary atmospheres. The goal of this project is to add to the potential of the HITRAN database towards the exploration of the planetary atmospheres by including parameters describing broadening of spectral lines by H2, CO2, and He. These spectroscopic data are very important for the study of the hydrogen and helium-rich atmospheres of gas giants as well as rocky planets with volcanic activities, including Venus and Mars, since their atmospheres are dominated by CO2. First step in this direction was accomplished by Wilzewski et al.3 where this was done for SO2, NH3, HF, HCl, OCS and C2H2. The molecules investigated in this work were CO2, N2O, H2CO, HCN and H2S. Line-broadening coefficients, line shifts and temperature-dependence exponents for transitions of these molecules perturbed by H2, CO2 and He have been assembled from available peer-reviewed experimental and theoretical sources. The data was evaluated and the database was populated with these data and their extrapolations/interpolations using semi-empirical models that were developed to this end.Acknowledgements: Financial support from NASA PDART grant NNX16AG51G and the Smithsonian Astrophysical Observatory Latino Initiative Program from the Latino Initiatives Pool, administered by the Smithsonian Latino Center is gratefully acknowledged.References: 1. HITRAN online http://hitran.org/2. Gordon, I.E., Rothman, L.S., Hill, C., Kochanov, R.V., Tan, Y., et al., 2017. The HITRAN2016 Molecular Spectroscopic Database. J. Quant. Spectrosc. Radiat. Transf. doi:10.1016/j.jqsrt.2017.06.0383. Wilzewski, J.S., Gordon, I.E., Kochanov, R. V., Hill, C., Rothman, L.S., 2016. H2, He, and CO2 line-broadening coefficients, pressure shifts and temperature-dependence exponents for the HITRAN database. Part 1: SO2, NH3, HF, HCl, OCS and C2H2. J. Quant. Spectrosc. Radiat

Gain-of-function mutations in potassium channel subunit KCNE2 associated with early-onset lone atrial fibrillation

DEFF Research Database (Denmark)

Nielsen, Jonas Bille; Bentzen, Bo Hjorth; Olesen, Morten Salling

2014-01-01

Aims: Atrial fibrillation (AF) is the most common cardiac arrhythmia. Disturbances in cardiac potassium conductance are considered as one of the disease mechanisms in AF. We aimed to investigate if mutations in potassium-channel β-subunits KCNE2 and KCNE3 are associated with early-onset lone AF. ...

The KCNE genes in hypertrophic cardiomyopathy: a candidate gene study

DEFF Research Database (Denmark)

Hedley, Paula L; Haundrup, Ole; Andersen, Paal S

2011-01-01

The gene family KCNE1-5, which encode modulating β-subunits of several repolarising K+-ion channels, has been associated with genetic cardiac diseases such as long QT syndrome, atrial fibrillation and Brugada syndrome. The minK peptide, encoded by KCNE1, is attached to the Z-disc of the sarcomere...... as well as the T-tubules of the sarcolemma. It has been suggested that minK forms part of an "electro-mechanical feed-back" which links cardiomyocyte stretching to changes in ion channel function. We examined whether mutations in KCNE genes were associated with hypertrophic cardiomyopathy (HCM), a genetic...

Arrhythmogenic KCNE gene variants: current knowledge and future challenges

Directory of Open Access Journals (Sweden)

Shawn M Crump

2014-01-01

Full Text Available There are twenty-five known inherited cardiac arrhythmia susceptibility genes, all of which encode either ion channel pore-forming subunits or proteins that regulate aspects of ion channel biology such as function, trafficking and localization. The human KCNE gene family comprises five potassium channel regulatory subunits, sequence variants in each of which are associated with cardiac arrhythmias. KCNE gene products exhibit promiscuous partnering and in some cases ubiquitous expression, hampering efforts to unequivocally correlate each gene to specific native potassium currents. Likewise, deducing the molecular etiology of cardiac arrhythmias in individuals harboring rare KCNE gene variants, or more common KCNE polymorphisms, can be challenging. In this review we provide an update on putative arrhythmia-causing KCNE gene variants, and discuss current thinking and future challenges in the study of molecular mechanisms of KCNE-associated cardiac rhythm disturbances.

Peripheral hyperpolarization-activated cyclic nucleotide-gated channels contribute to inflammation-induced hypersensitivity of the rat temporomandibular joint.

Science.gov (United States)

Hatch, R J; Jennings, E A; Ivanusic, J J

2013-08-01

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels conduct an inward cation current (Ih ) that contributes to the maintenance of neuronal membrane potential and have been implicated in a number of animal models of neuropathic and inflammatory pain. In the current study, we investigated HCN channel involvement in inflammatory pain of the temporomandibular joint (TMJ). The contribution of HCN channels to inflammation (complete Freund's adjuvant; CFA)-induced mechanical hypersensitivity of the rat TMJ was tested with injections of the HCN channel blocker ZD7288. Retrograde labelling and immunohistochemistry was used to explore HCN channel expression in sensory neurons that innervate the TMJ. Injection of CFA into the TMJ (n = 7) resulted in a significantly increased mechanical sensitivity relative to vehicle injection (n = 7) (p blocked by co-injection of ZD7288 with the CFA (n = 7). Retrograde labelling and immunohistochemistry experiments revealed expression predominantly of HCN1 and HCN2 channel subunits in trigeminal ganglion neurons that innervate the TMJ (n = 3). No change in the proportion or intensity of HCN channel expression was found in inflamed (n = 6) versus control (n = 5) animals at the time point tested. Our findings suggest a role for peripheral HCN channels in inflammation-induced pain of the TMJ. Peripheral application of a HCN channel blocker could provide therapeutic benefit for inflammatory TMJ pain and avoid side effects associated with activation of HCN channels in the central nervous system. © 2012 European Federation of International Association for the Study of Pain Chapters.

Molecular cloning and functional expression of the Equine K+ channel KV11.1 (Ether à Go-Go-related/KCNH2 gene) and the regulatory subunit KCNE2 from equine myocardium

DEFF Research Database (Denmark)

Pedersen, Philip Juul; Thomsen, Kirsten Brolin; Olander, Emma Rie

2015-01-01

and conventional PCR on mRNA purified from equine myocardial tissue. Equine KV11.1 and KCNE2 cDNA had a high homology to human genes (93 and 88%, respectively). Equine and human KV11.1 and KV11.1/KCNE2 were expressed in Xenopus laevis oocytes and investigated by two-electrode voltage-clamp. Equine KV11.1 currents...... were larger compared to human KV11.1, and the voltage dependence of activation was shifted to more negative values with V1/2 = -14.2±1.1 mV and -17.3±0.7, respectively. The onset of inactivation was slower for equine KV11.1 compared to the human homolog. These differences in kinetics may account...... for the larger amplitude of the equine current. Furthermore, the equine KV11.1 channel was susceptible to pharmacological block with terfenadine. The physiological importance of KV11.1 was investigated in equine right ventricular wedge preparations. Terfenadine prolonged action potential duration and the effect...

A Reduced Reaction Scheme for Volatile Nitrogen Conversion in Coal Combustion

DEFF Research Database (Denmark)

Pedersen, Lars Saaby; Glarborg, Peter; Dam-Johansen, Kim

1998-01-01

In pulverised coal flames, the most important volatile nitrogen component forming NOx is HCN. To be able to model the nitrogen chemistry in coal flames it is necessary to have an adequate model for HCN oxidation. The present work was concerned with developing a model for HCN/NH3/NO conversion based...... that the CO/H-2 chemistry was described adequately, the reduced HCN/NH3/NO model compared very well with the detailed model over a wide range of stoichiometries. Decoupling of the HCN chemistry from the CO/H-2 chemistry resulted in over-prediction of the HCN oxidation rate under fuel rich conditions, but had...... negligible effect on the CO/H-2 chemistry. Comparison with simplified HCN models from the literature revealed significant differences, indicating that these models should be used cautiously in modelling volatile nitrogen conversion....

Chemical evolution. XXIX - Pyrimidines from hydrogen cyanide

Science.gov (United States)

Ferris, J. P.; Joshi, P. C.; Lawless, J. G.

1978-01-01

Compounds obtained by hydrolysis of HCN oligomers formed by allowing pH 9.2, 0.1 M cyanide to stand at room temperature for 4 to 12 months were analyzed. Hydrolysis of HCN oligomers yielded 4,5-dihydroxypyrimidine and 5-hydroxyuracil; orotic acid was detected after hydrolysis at pH 8.5. A unified pathway from diaminofumaronitrile to the pyrimidines observed is suggested. As purines, pyrimidines and amino acids are released by hydrolysis of HCN oligomers in either acidic or mildly basic aqueous solutions, they could have been formed on the primitive earth in spite of fluctuations in pH. 4,5-dihydroxypyrimidines appear to be likely candidates for incorporation into primitive nucleic acids, as they should undergo Watson-Crick hydrogen bonding with adenine.

MLS measurements of stratospheric hydrogen cyanide during the 2015-2016 El Niño event

Science.gov (United States)

Pumphrey, Hugh C.; Glatthor, Norbert; Bernath, Peter F.; Boone, Christopher D.; Hannigan, James W.; Ortega, Ivan; Livesey, Nathaniel J.; Read, William G.

2018-01-01

It is known from ground-based measurements made during the 1982-1983 and 1997-1998 El Niño events that atmospheric hydrogen cyanide (HCN) tends to be higher during such years than at other times. The Microwave Limb Sounder (MLS) on the Aura satellite has been measuring HCN mixing ratios since launch in 2004; the measurements are ongoing at the time of writing. The winter of 2015-2016 saw the largest El Niño event since 1997-1998. We present MLS measurements of HCN in the lower stratosphere for the Aura mission to date, comparing the 2015-2016 El Niño period to the rest of the mission. HCN in 2015-2016 is higher than at any other time during the mission, but ground-based measurements suggest that it may have been even more elevated in 1997-1998. As the MLS HCN data are essentially unvalidated, we show them alongside data from the MIPAS and ACE-FTS instruments; the three instruments agree reasonably well in the tropical lower stratosphere. Global HCN emissions calculated from the Global Fire Emissions Database (GFED v4.1) database are much greater during large El Niño events and are greater in 1997-1998 than in 2015-2016, thereby showing good qualitative agreement with the measurements. Correlation between El Niño-Southern Oscillation (ENSO) indices, measured HCN, and GFED HCN emissions is less clear if the 2015-2016 event is excluded. In particular, the 2009-2010 winter had fairly strong El Niño conditions and fairly large GFED HCN emissions, but very little effect is observed in the MLS HCN.

Alma observations of nearby luminous infrared galaxies with various agn energetic contributions using dense gas tracers

Energy Technology Data Exchange (ETDEWEB)

Imanishi, Masatoshi [Subaru Telescope, 650 North A' ohoku Place, Hilo, HI 96720 (United States); Nakanishi, Kouichiro, E-mail: masa.imanishi@nao.ac.jp [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

2014-07-01

We present the results of our ALMA Cycle 0 observations, using HCN/HCO{sup +}/HNC J = 4-3 lines, of six nearby luminous infrared galaxies with various energetic contributions from active galactic nuclei (AGNs) estimated from previous infrared spectroscopy. These lines are very effective for probing the physical properties of high-density molecular gas around the hidden energy sources in the nuclear regions of these galaxies. We find that HCN to HCO{sup +} J = 4-3 flux ratios tend to be higher in AGN-important galaxies than in starburst-dominated regions, as was seen at the J = 1-0 transition, while there is no clear difference in the HCN-to-HNC J = 4-3 flux ratios among observed sources. A galaxy with a starburst-type infrared spectral shape and very large molecular line widths shows a high HCN-to-HCO{sup +} J = 4-3 flux ratio, which could be due to turbulence-induced heating. We propose that enhanced HCN J = 4-3 emission relative to HCO{sup +} J = 4-3 could be used to detect more energetic activity than normal starbursts, including deeply buried AGNs, in dusty galaxy populations.

Detection of hydrogen cyanide from oral anaerobes by cavity ring down spectroscopy

Science.gov (United States)

Chen, Wen; Roslund, Kajsa; Fogarty, Christopher L.; Pussinen, Pirkko J.; Halonen, Lauri; Groop, Per-Henrik; Metsälä, Markus; Lehto, Markku

2016-03-01

Hydrogen cyanide (HCN) has been recognized as a potential biomarker for non-invasive diagnosis of Pseudomonas aeruginosa infection in the lung. However, the oral cavity is a dominant production site for exhaled HCN and this contribution can mask the HCN generated in the lung. It is thus important to understand the sources of HCN production in the oral cavity. By screening of oral anaerobes for HCN production, we observed that the genus of Porphyromonas, Prevotella and Fusobacterium generated low levels of HCN in vitro. This is the first study to show that oral anaerobes are capable of producing HCN in vitro. Further investigations were conducted on the species of P. gingivalis and we successfully detected HCN production (0.9-10.9 ppb) in the headspace of three P. gingivalis reference strains (ATCC 33277, W50 and OMG 434) and one clinical isolate. From P. gingivalis ATCC 33277 and W50, a strong correlation between HCN and CO2 concentrations (rs = 0.89, p < 0.001) was observed, indicating that the HCN production of P. gingivalis might be connected with the bacterial metabolic activity. These results indicate that our setup could be widely applied to the screening of in vitro HCN production by both aerobic and anaerobic bacteria.

The Composition of Comet C/2012 K1 (PanSTARRS) and the Distribution of Primary Volatile Abundances Among Comets

Energy Technology Data Exchange (ETDEWEB)

Roth, Nathan X.; Gibb, Erika L. [Department of Physics and Astronomy, University of Missouri-St. Louis, 503 Benton Hall, One University Blvd., St. Louis, MO 63121 (United States); Bonev, Boncho P.; DiSanti, Michael A.; Mumma, Michael J.; Villanueva, Geronimo L.; Paganini, Lucas, E-mail: nxrq67@mail.umsl.edu [Goddard Center for Astrobiology, NASA Goddard Space Flight Center, Mail Stop 690, Greenbelt, MD 20771 (United States)

2017-04-01

On 2014 May 22 and 24 we characterized the volatile composition of the dynamically new Oort cloud comet C/2012 K1 (PanSTARRS) using the long-slit, high resolution ( λ /Δ λ  ≈ 25,000) near-infrared echelle spectrograph (NIRSPEC) at the 10 m Keck II telescope on Maunakea, Hawaii. We detected fluorescent emission from six primary volatiles (H{sub 2}O, HCN, CH{sub 4}, C{sub 2}H{sub 6}, CH{sub 3}OH, and CO). Upper limits were derived for C{sub 2}H{sub 2}, NH{sub 3}, and H{sub 2}CO. We report rotational temperatures, production rates, and mixing ratios (relative to water). Compared with median abundance ratios for primary volatiles in other sampled Oort cloud comets, trace gas abundance ratios in C/2012 K1 (PanSTARRS) for CO and HCN are consistent, but CH{sub 3}OH and C{sub 2}H{sub 6} are enriched while H{sub 2}CO, CH{sub 4}, and possibly C{sub 2}H{sub 2} are depleted. When placed in context with comets observed in the near-infrared to date, the data suggest a continuous distribution of abundances of some organic volatiles (HCN, C{sub 2}H{sub 6}, CH{sub 3}OH, CH{sub 4}) among the comet population. The level of “enrichment” or “depletion” in a given comet does not necessarily correlate across all molecules sampled, suggesting that chemical diversity among comets may be more complex than the simple organics-enriched, organics-normal, and organics-depleted framework.

Radiation-induced polymerization of hydrogen cyanide

International Nuclear Information System (INIS)

Mozhaev, P.S.; Kichigina, G.A.; Kiryukhin, D.P.

1995-01-01

The chain reaction of HCN polymerization in a γ-radiation field does not occur at 77 K. When irradiated HCN is warmed up to ambient temperature, a polymer is formed. The heat of polymerization of HCN is 44.0±6.0 kJ/mol and the polymer yield reaches 2.5% for a dose of 725 kGy. Amorphous polymer products (with yields increasing up to 33.5%) and needle crystals (presumably HCN tetramer) are formed upon storage of irradiated HCN at room temperature. The polymer is stable below 700 K, has a conductivity of 3x10 -5 Ω -1 cm -f1 , and displays an EPR spectrum typical of polyconjugated systems. A radical mechanism of the formation of conjugated chain -C=N-C=N- is suggested. The tetramer is produced by a combination of aminocyanocarbene biradicals

TESTING THE GLOBAL STAR FORMATION RELATION: AN HCO+ (3-2) MAPPING STUDY OF RED MSX SOURCES IN THE BOLOCAM GALACTIC PLANE SURVEY

International Nuclear Information System (INIS)

Schenck, David E.; Shirley, Yancy L.; Reiter, Megan; Juneau, Stephanie

2011-01-01

We present an analysis of the relation between the star formation rate (SFR) and mass of dense gas in Galactic clumps and nearby galaxies. Using the bolometric luminosity as a measure of SFR and the molecular line luminosity of HCO + (3-2) as a measure of dense gas mass, we find that the relation between SFR and M dense is approximately linear. This is similar to published results derived using HCN (1-0) as a dense gas tracer. HCO + (3-2) and HCN (1-0) have similar conditions for excitation. Our work includes 16 Galactic clumps that are in both the Bolocam Galactic Plane Survey and the Red MSX Source Survey, 27 water maser sources from the literature, and the aforementioned HCN (1-0) data. Our results agree qualitatively with predictions of recent theoretical models which state that the nature of the relation should depend on how the critical density of the tracer compares with the mean density of the gas.

A Multi-Wavelength Study of Parent Volatile Abundances in Comet C/2006 M4 (SWAN)

Science.gov (United States)

DiSanti, Michael A.; Villanueva, Geronimo L.; Milam, Stefanie N.; Zack, Lindsay N.; Bonev, Boncho P.; Mumma, Michael; Ziurys, Lucy M.; Anderson, William M.

2009-01-01

Volatile organic emissions were detected post-perihelion in the long period comet C/2006 M4 (SWAN) in October and November 2006. Our study combines target-of-opportunity, observations using the infrared Cryogenic Echelle Spectrometer (CSHELL) at the NASA-IRTF 3-m telescope, and millimeter wavelength observations using the Arizona Radio Observatory (ARO) 12-m telescope. Five parent volatiles were measured with CSHELL (H2O, CO, CH3OH, CH4, and C2H6), and two additional species (HCN and CS) were measured with the ARID 12-m. These revealed highly depleted CO and somewhat enriched CH3OH compared with abundances observed in the dominant group of long-period (Oort cloud) comets in our sample and similar to those observed recently in Comet 8P/Tuttle. This may indicate highly efficient H-atom addition to CO at very low temperature (approx.10-20 K) on the surfaces of interstellar (pre-cometary) grains. Comet C12006 M4 had nearly "normal" C2H6, and CH4, suggesting a processing history similar to that experienced by the dominant group. When compared with estimated water production at the time of the millimeter observations, HCN was slightly depleted compared with the normal abundance in comets based on 1R observations but was consistent with the majority of values from the millimeter. The ratio CS/HCN in C/2006 M4 was within the range measured in ten comets at millimeter wavelengths. The higher apparent H-atom conversion efficiency compared with most comets may indicate that the icy grains incorporated into C/2006 M4 were exposed to higher H-atom densities, or alternatively to similar densities but for a longer period of time.

Studies on some important secondary metabolites from marine organisms

Digital Repository Service at National Institute of Oceanography (India)

Parvatkar, R.R.

-(2,4- dibromo-5-methoxyphenyl)ethanamine (15) from this species suggest that amathamides and amathaspiramides are biosynthesized from phenylalanine by a series of aromatic substitution reactions and a decarboxylation giving the amines of the type 15, which... an aldehyde with HCN. HCN is generated in situ from cyanide salt such as NaCN, KCN, etc by treatment with a mineral acid. It is not safe to use HCN or its salts owing to its toxic effects that are fatal. Moreover, the yields of these reactions are poor...

ALMA 0.1–0.2 arcsec resolution imaging of the NGC 1068 Nucleus: compact dense molecular gas emission at the putative AGN location

Energy Technology Data Exchange (ETDEWEB)

Imanishi, Masatoshi [Subaru Telescope, 650 North A’ohoku Place, Hilo, HI 96720 (United States); Nakanishi, Kouichiro [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Izumi, Takuma, E-mail: masa.imanishi@nao.ac.jp [Institute of Astronomy, School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan)

2016-05-01

We present the results of our ALMA Cycle 2 high angular resolution (0.″1–0.″2) observations of the nuclear region of the nearby well-studied type-2 active galactic nucleus (AGN), NGC 1068, at HCN J = 3–2 and HCO{sup +} J = 3–2 emission lines. For the first time, due to a higher angular resolution than previous studies, we clearly detected dense molecular gas emission at the putative AGN location, identified as a ∼1.1 mm (∼266 GHz) continuum emission peak, by separating this emission from brighter emission located at 0.″5–2.″0 on the eastern and western sides of the AGN. The estimated intrinsic molecular emission size and dense molecular mass, which are thought to be associated with the putative dusty molecular torus around an AGN, were ∼10 pc and ∼several × 10{sup 5} M {sub ⊙}, respectively. HCN-to-HCO{sup +} J = 3–2 flux ratios substantially higher than unity were found throughout the nuclear region of NGC 1068. The continuum emission displayed an elongated morphology along the direction of the radio jet located at the northern side of the AGN, as well as a weak spatially-resolved component at ∼2.″0 on the southwestern side of the AGN. The latter component most likely originated from star formation, with the estimated luminosity more than one order of magnitude lower than the luminosity of the central AGN. No vibrationally excited ( v {sub 2} = 1f) J = 3–2 emission lines were detected for HCN and HCO{sup +} across the field of view.

Corona discharge experiments in admixtures of N2 and CH4: a laboratory simulation of Titan's atmosphere

OpenAIRE

Horvath, G.; Skalny, J. D.; Mason, N. J.; Klas, M.; Zahoran, M.; Vladoiu, R.; Manole, M.

2009-01-01

A positive corona discharge fed by a N2:CH4 mixture (98:2) at atmospheric pressure and ambient temperature has been studied as a laboratory mimic of the chemical processes occurring in the atmosphere of Titan, Saturn's largest moon. In-situ measurements of UV and IR transmission spectra within the discharge have shown that the main chemical product is C2H2, produced by dissociation of CH4, with small but significant traces of ethane and HCN, all species that have been detected in Titan's atmo...

Search after new agents for hyperpolarization-activated and cyclic nucleotide-gated ion channels; Suche nach neuen Wirkstoffen fuer Hyperpolarisationsaktivierte und zyklisch Nukleotid-gesteuerte Ionenkanaele

Energy Technology Data Exchange (ETDEWEB)

Struenker, T.

2005-12-01

Rhythmic activity of single cells or cellular networks is a common feature of most organisms. Cellular rhythms govern the beating of the heart, cycles of sleep and wakefulness, breathing, and the release of hormones. The endogenous rhythmic activity of many neurons and cardiac relies on a complex interplay between several distinct ion channels. In particular, one type of ion channel plays a prominent role in the control of rhythmic electrical activity because it determines the frequency of the oscillations. The activity of the channels is thus setting the ''pace'' of the activity; therefore, these channels are often referred to as ''pacemaker'' channels. Despite their obvious physiological importance it hasn't been until a few years ago that the genes encoding pacemaker channels have been identified. Because both hyperpolarization and cyclic nucleotides are key elements that control their activity, pacemaker channels have now been designated hyperpolarization-activated and cyclic nucleotide-gated (HCN) channels. From a scientific as well as medical point of view, HCN channels are interesting drug targets. Only a few substances are known that specifically affect HCN channels. In the present study, a microtiter plate-based high throughput screening assay for HCN1 and HCN4 channels was developed. With this assay, known drugs for HCN channels were characterized. Subsequently, venoms of snails, spiders, scorpions, and snakes were screened for toxins affecting HCN channel activity. A few venoms were identified that possibly contain drugs that act on HCN channels. (orig.)

Deubiquitylating enzyme USP2 counteracts Nedd4-2-mediated downregulation of KCNQ1 potassium channels

DEFF Research Database (Denmark)

Krzystanek, Katarzyna; Rasmussen, Hanne Borger; Grunnet, Morten

2012-01-01

KCNQ1 (Kv7.1), together with its KCNE ß subunits, plays a pivotal role both in the repolarization of cardiac tissue and in water and salt transport across epithelial membranes. Nedd4/Nedd4-like (neuronal precursor cell-expressed developmentally downregulated 4) ubiquitin-protein ligases interact ...

CHEMICAL CONSEQUENCES OF THE C/O RATIO ON HOT JUPITERS: EXAMPLES FROM WASP-12b, CoRoT-2b, XO-1b, AND HD 189733b

Energy Technology Data Exchange (ETDEWEB)

Moses, J. I. [Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301 (United States); Madhusudhan, N. [Department of Physics and Department of Astronomy, Yale University, New Haven, CT 06520-8101 (United States); Visscher, C. [Southwest Research Institute, Boulder, CO 80302 (United States); Freedman, R. S., E-mail: jmoses@spacescience.org [SETI Institute, Mountain View, CA 94043 (United States)

2013-01-20

Motivated by recent spectroscopic evidence for carbon-rich atmospheres on some transiting exoplanets, we investigate the influence of the C/O ratio on the chemistry, composition, and spectra of extrasolar giant planets both from a thermochemical equilibrium perspective and from consideration of disequilibrium processes like photochemistry and transport-induced quenching. We find that although CO is predicted to be a major atmospheric constituent on hot Jupiters for all C/O ratios, other oxygen-bearing molecules like H{sub 2}O and CO{sub 2} are much more abundant when C/O < 1, whereas CH{sub 4}, HCN, and C{sub 2}H{sub 2} gain significantly in abundance when C/O > 1. Other notable species like N{sub 2} and NH{sub 3} that do not contain carbon or oxygen are relatively unaffected by the C/O ratio. Disequilibrium processes tend to enhance the abundance of CH{sub 4}, NH{sub 3}, HCN, and C{sub 2}H{sub 2} over a wide range of C/O ratios. We compare the results of our models with secondary-eclipse photometric data from the Spitzer Space Telescope and conclude that (1) disequilibrium models with C/O {approx} 1 are consistent with spectra of WASP-12b, XO-1b, and CoRoT-2b, confirming the possible carbon-rich nature of these planets; (2) spectra from HD 189733b are consistent with C/O {approx}< 1, but as the assumed metallicity is increased above solar, the required C/O ratio must increase toward 1 to prevent too much H{sub 2}O absorption; (3) species like HCN can have a significant influence on spectral behavior in the 3.6 and 8.0 {mu}m Spitzer channels, potentially providing even more opacity than CH{sub 4} when C/O > 1; and (4) the very high CO{sub 2} abundance inferred for HD 189733b from near-infrared observations cannot be explained through equilibrium or disequilibrium chemistry in a hydrogen-dominated atmosphere. We discuss possible formation mechanisms for carbon-rich hot Jupiters, including scenarios in which the accretion of CO-rich, H{sub 2}O-poor gas dominates the

Formation of 1,2-diaminomaleicdinitrile crystals in radiolized solid hydrogen cyanide

International Nuclear Information System (INIS)

Mozhaev, P.S.; Kichigina, G.A.; Aliev, Z.G.; Kiryukhin, D.P.; Atovmyan, L.O.; Barkalov, I.M.

1994-01-01

A study was made on possibility of formation of 1,2-diaminomaleicdinitrile and mechanism of its occurrence in space environment. It was shown in experiments, that 1,2-diaminomaleicdinitrile crystals formed in solid HCN matrix, decomposed radiolytically at 77 K by 60 Co γ-rays with dose of 800 kGy during its sublimation T ≤ 260 K along with conjugated polymer of -C=N-C=N- type. It is shown that radiolysis of solid hydrocyanic acid results to formation of 1,2-diaminomaleicdinitrile with radiation yield G > 2. 11 refs., 1 fig., 1 tab

Combustion products from various kinds of fibers: toxicological hazards from smoke exposure. [Guinea pigs

Energy Technology Data Exchange (ETDEWEB)

Betol, E.; Mari, F.; Orzalesi, G.; Volpato, I.

1983-08-15

The smoke exposure hazards during combustion of carbon and nitrogen-containing fibers were evaluated in guinea pigs intoxicated by gradual exposure to HCN and CO neo-formed from foam rubber, wool and PAN (Polyacrylonitrile). The most prominent result of our study was that the neo-formation of HCN from 1 g of PAN was 1500 ppm, much higher than from foam rubber and wool because of the presence of many -CN groups in the polymer chemical structure. This concentration of HCN is estimated to be lethal. Extrapolating this data, a lethal concentration of HCN could be obtained by burning 2 kg of PAN in an average sized living room. The above-mentioned 1 g of PAN was burned in a 15.6-liter combustion chamber.

Some problems in interpretation of the New Horizons observations of Pluto's atmosphere

Science.gov (United States)

Krasnopolsky, Vladimir A.

2018-02-01

Here I briefly discuss the following problems related to Pluto's atmosphere: (1) restrictions to LTE in the rotational lines of H2O and HCN above 700 km that affect thermal balance of the atmosphere; (2) contradictions in the estimates of H2O influx from ablation of the interplanetary dust; (3) great difference between the haze volume surface area in the LORRI and MVIC observations and that in the UV solar occultations and the models, including significant corrections to sticking coefficients of C2H2, C2H4, C2H6, and HCN in condensation, and (4) Triton's thermosphere during the Voyager 2 flyby.

First Measurement of the 14N/15N Ratio in the Analog of the Sun Progenitor OMC-2 FIR4

Science.gov (United States)

Kahane, Claudine; Jaber Al-Edhari, Ali; Ceccarelli, Cecilia; López-Sepulcre, Ana; Fontani, Francesco; Kama, Mihkel

2018-01-01

We present a complete census of the 14N/15N isotopic ratio in the most abundant N-bearing molecules toward the cold envelope of the protocluster OMC-2 FIR4, the best known Sun progenitor. To this scope, we analyzed the unbiased spectral survey obtained with the IRAM 30 m telescope at 3, 2, and 1 mm. We detected several lines of CN, HCN, HNC, HC3N, N2H+, and their respective 13C and 15N isotopologues. The lines’ relative fluxes are compatible with LTE conditions, and moderate line opacities have been corrected via a population diagram method or theoretical relative intensity ratios of the hyperfine structures. The five species lead to very similar 14N/15N isotopic ratios, without any systematic difference between amine- and nitrile-bearing species as previously found in other protostellar sources. The weighted average of the 14N/15N isotopic ratio is 270 ± 30. This 14N/15N value is remarkably consistent with the [250–350] range measured for the local galactic ratio but significantly differs from the ratio measured in comets (around 140). High-angular resolution observations are needed to examine whether this discrepancy is maintained at smaller scales. In addition, using the CN, HCN, and HC3N lines, we derived a 12C/13C isotopic ratio of 50 ± 5.

Importance of the Hydrogen Isocyanide Isomer in Modeling Hydrogen Cyanide Oxidation in Combustion

DEFF Research Database (Denmark)

Glarborg, Peter; Marshall, Paul

2017-01-01

Hydrogen isocyanide (HNC) has been proposed as an important intermediate in oxidation of hydrogen cyanide (HCN) in combustion, but details of its chemistry are still in discussion. At higher temperatures, HCN and HNC equilibrate rapidly, and being more reactive than HCN, HNC offers a fast alterna...... HNCO is the major consumption path for HCN. Under lean conditions, HNC is shown to be less important than indicated by the early work by Lin and co-workers, but it acts to accelerate HCN oxidation and promotes the formation of HNCO.......Hydrogen isocyanide (HNC) has been proposed as an important intermediate in oxidation of hydrogen cyanide (HCN) in combustion, but details of its chemistry are still in discussion. At higher temperatures, HCN and HNC equilibrate rapidly, and being more reactive than HCN, HNC offers a fast...

C,N-2-[(Dimethylamino)methyl]phenylplatinum Complexes Functionalized with C60 as Macromolecular Building Blocks

NARCIS (Netherlands)

Koten, G. van; Meijer, M.D.; Wolf, E. de; Lutz, M.H.; Spek, A.L.; Klink, G.P.M. van

2001-01-01

The application of platinum(II) complexes based on the N,N-dimethylbenzylamine ligand (abbreviated as H-C,N) in macromolecular synthesis was demonstrated. Two cationic C,N-platinum moieties were linked with a 4,4'-bipyridine bridge, giving [{C6H4(CH2NMe2)-2-Pt(PPh3)}2(4,4'-bpy)](BF4)2 (2), the

Rates and equilibrium constants of the ligand-induced conformational transition of an HCN ion channel protein domain determined by DEER spectroscopy.

Science.gov (United States)

Collauto, Alberto; DeBerg, Hannah A; Kaufmann, Royi; Zagotta, William N; Stoll, Stefan; Goldfarb, Daniella

2017-06-14

Ligand binding can induce significant conformational changes in proteins. The mechanism of this process couples equilibria associated with the ligand binding event and the conformational change. Here we show that by combining the application of W-band double electron-electron resonance (DEER) spectroscopy with microfluidic rapid freeze quench (μRFQ) it is possible to resolve these processes and obtain both equilibrium constants and reaction rates. We studied the conformational transition of the nitroxide labeled, isolated carboxy-terminal cyclic-nucleotide binding domain (CNBD) of the HCN2 ion channel upon binding of the ligand 3',5'-cyclic adenosine monophosphate (cAMP). Using model-based global analysis, the time-resolved data of the μRFQ DEER experiments directly provide fractional populations of the open and closed conformations as a function of time. We modeled the ligand-induced conformational change in the protein using a four-state model: apo/open (AO), apo/closed (AC), bound/open (BO), bound/closed (BC). These species interconvert according to AC + L ⇌ AO + L ⇌ BO ⇌ BC. By analyzing the concentration dependence of the relative contributions of the closed and open conformations at equilibrium, we estimated the equilibrium constants for the two conformational equilibria and the open-state ligand dissociation constant. Analysis of the time-resolved μRFQ DEER data gave estimates for the intrinsic rates of ligand binding and unbinding as well as the rates of the conformational change. This demonstrates that DEER can quantitatively resolve both the thermodynamics and the kinetics of ligand binding and the associated conformational change.

CYANIDE PHOTOCHEMISTRY AND NITROGEN FRACTIONATION IN THE MWC 480 DISK

Energy Technology Data Exchange (ETDEWEB)

Guzmán, V. V.; Öberg, K. I.; Loomis, R.; Qi, C., E-mail: vguzman@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2015-11-20

HCN is a commonly observed molecule in Solar System bodies and in interstellar environments. Its abundance with respect to CN is a proposed tracer of UV exposure. HCN is also frequently used to probe the thermal history of objects, by measuring its degree of nitrogen fractionation. To address the utility of HCN as a probe of disks, we present Atacama Large (sub-) Millimeter Array observations of CN, HCN, H{sup 13}CN, and HC{sup 15}N toward the protoplanetary disk around Herbig Ae star MWC 480, and of CN and HCN toward the disk around T Tauri star DM Tau. Emission from all molecules is clearly detected and spatially resolved, including the first detection of HC{sup 15}N in a disk. Toward MWC 480, CN emission extends radially more than 1″ exterior to the observed cut-off of HCN emission. Quantitative modeling further reveals very different radial abundance profiles for CN and HCN, with best-fit outer cut-off radii of >300 AU and 110 ± 10 AU, respectively. This result is in agreement with model predictions of efficient HCN photodissociation into CN in the outer-part of the disk where the vertical gas and dust column densities are low. No such difference in CN and HCN emission profiles are observed toward DM Tau, suggestive of different photochemical structures in Herbig Ae and T Tauri disks. We use the HCN isotopologue data toward the MWC 480 disk to provide the first measurement of the {sup 14}N/{sup 15}N ratio in a disk. We find a low disk averaged {sup 14}N/{sup 15}N ratio of 200 ± 100, comparable to what is observed in cloud cores and comets, demonstrating interstellar inheritance and/or efficient nitrogen fractionation in this disk.

Emissions of hydrogen cyanide from on-road gasoline and diesel vehicles

Science.gov (United States)

Moussa, Samar G.; Leithead, Amy; Li, Shao-Meng; Chan, Tak W.; Wentzell, Jeremy J. B.; Stroud, Craig; Zhang, Junhua; Lee, Patrick; Lu, Gang; Brook, Jeffery R.; Hayden, Katherine; Narayan, Julie; Liggio, John

2016-04-01

Hydrogen cyanide (HCN) is considered a marker for biomass burning emissions and is a component of vehicle exhaust. Despite its potential health impacts, vehicular HCN emissions estimates and their contribution to regional budgets are highly uncertain. In the current study, Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS) was used to measure HCN emission factors from the exhaust of individual diesel, biodiesel and gasoline vehicles. Laboratory emissions data as a function of fuel type and driving mode were combined with ambient measurement data and model predictions. The results indicate that gasoline vehicles have the highest emissions of HCN (relative to diesel fuel) and that biodiesel fuel has the potential to significantly reduce HCN emissions even at realistic 5% blend levels. The data further demonstrate that gasoline direct injection (GDI) engines emit more HCN than their port fuel injection (PFI) counterparts, suggesting that the expected full transition of vehicle fleets to GDI will increase HCN emissions. Ambient measurements of HCN in a traffic dominated area of Toronto, Canada were strongly correlated to vehicle emission markers and consistent with regional air quality model predictions of ambient air HCN, indicating that vehicle emissions of HCN are the dominant source of exposure in urban areas. The results further indicate that additional work is required to quantify HCN emissions from the modern vehicle fleet, particularly in light of continuously changing engine, fuel and after-treatment technologies.

Solid-State Chemistry as a Formation Mechanism for C 4N 2 Ice and Possibly the Haystack (220 cm -1 ice emission feature) in Titan's Stratosphere as Observed by Cassini CIRS

Science.gov (United States)

Anderson, Carrie; Samuelson, Robert E.; McLain, Jason L.; Nna Mvondo, Delphine; Romani, Paul; Flasar, F. Michael

2016-10-01

A profusion of organic ices containing hydrocarbons, nitriles, and combinations of their mixtures comprise Titan's complex stratospheric cloud systems, and are typically formed via vapor condensation. These ice particles are then distributed throughout the mid-to-lower stratosphere, with an increased abundance near the winter poles (see Anderson et al., 2016). The cold temperatures and the associated strong circumpolar winds that isolate polar air act in much the same way as on Earth, giving rise to compositional anomalies and stratospheric clouds that provide heterogeneous chemistry sites.Titan's C4N2 ice emission feature at 478 cm-1 and "the Haystack," a strong unidentified stratospheric ice emission feature centered at 220 cm-1, share a common characteristic. Even though both are distinctive ice emission features evident in Cassini Composite InfraRed (CIRS) far-IR spectra, no associated vapor emission features can be found in Titan's atmosphere. Without a vapor phase, solid-state chemistry provides an alternate mechanism beside vapor condensation for producing these observed stratospheric ices.Anderson et al., (2016) postulated that C4N2 ice formed in Titan's stratosphere via the solid-state photochemical reaction HCN + HC3N → C4N2 + H2 can occur within extant HCN-HC3N composite ice particles. Such a reaction, and potentially similar reactions that may produce the Haystack ice, are specific examples of solid-state chemistry in solar system atmospheres. This is in addition to the reaction HCl + ClONO2 → HNO3 + Cl2, which is known to produce HNO3 coatings on terrestrial water ice particles, a byproduct of the catalytic chlorine chemistry that produces ozone holes in Earth's polar stratosphere (see for example, Molina et al., 1987 Soloman, 1999).A combination of radiative transfer modeling of CIRS far-IR spectra, coupled with optical constants derived from thin film transmittance spectra of organic ice mixtures obtained in our Spectroscopy for Planetary ICes

[Development and Application of a Performance Prediction Model for Home Care Nursing Based on a Balanced Scorecard using the Bayesian Belief Network].

Science.gov (United States)

Noh, Wonjung; Seomun, Gyeongae

2015-06-01

This study was conducted to develop key performance indicators (KPIs) for home care nursing (HCN) based on a balanced scorecard, and to construct a performance prediction model of strategic objectives using the Bayesian Belief Network (BBN). This methodological study included four steps: establishment of KPIs, performance prediction modeling, development of a performance prediction model using BBN, and simulation of a suggested nursing management strategy. An HCN expert group and a staff group participated. The content validity index was analyzed using STATA 13.0, and BBN was analyzed using HUGIN 8.0. We generated a list of KPIs composed of 4 perspectives, 10 strategic objectives, and 31 KPIs. In the validity test of the performance prediction model, the factor with the greatest variance for increasing profit was maximum cost reduction of HCN services. The factor with the smallest variance for increasing profit was a minimum image improvement for HCN. During sensitivity analysis, the probability of the expert group did not affect the sensitivity. Furthermore, simulation of a 10% image improvement predicted the most effective way to increase profit. KPIs of HCN can estimate financial and non-financial performance. The performance prediction model for HCN will be useful to improve performance.

Airborne hydrogen cyanide measurements using a chemical ionisation mass spectrometer for the plume identification of biomass burning forest fires

Directory of Open Access Journals (Sweden)

M. Le Breton

2013-09-01

Full Text Available A chemical ionisation mass spectrometer (CIMS was developed for measuring hydrogen cyanide (HCN from biomass burning events in Canada using I− reagent ions on board the FAAM BAe-146 research aircraft during the BORTAS campaign in 2011. The ionisation scheme enabled highly sensitive measurements at 1 Hz frequency through biomass burning plumes in the troposphere. A strong correlation between the HCN, carbon monoxide (CO and acetonitrile (CH3CN was observed, indicating the potential of HCN as a biomass burning (BB marker. A plume was defined as being 6 standard deviations above background for the flights. This method was compared with a number of alternative plume-defining techniques employing CO and CH3CN measurements. The 6-sigma technique produced the highest R2 values for correlations with CO. A normalised excess mixing ratio (NEMR of 3.68 ± 0.149 pptv ppbv−1 was calculated, which is within the range quoted in previous research (Hornbrook et al., 2011. The global tropospheric model STOCHEM-CRI incorporated both the observed ratio and extreme ratios derived from other studies to generate global emission totals of HCN via biomass burning. Using the ratio derived from this work, the emission total for HCN from BB was 0.92 Tg (N yr−1.

Evidence of amino acid precursors: C-N bond coupling in simulated interstellar CO2/NH3 ices

Science.gov (United States)

Esmaili, Sasan

2015-08-01

Low energy secondary electrons are abundantly produced in astrophysical or planetary ices by the numerous ionizing radiation fields typically encountered in space environments and may thus play a role in the radiation processing of such ices [1]. One approach to determine their chemical effect is to irradiate nanometer thick molecular solids of simple molecular constituents, with energy selected electron beams and to monitor changes in film chemistry with the surface analytical techniques [2].Of particular interest is the formation of HCN, which is a signature of dense gases in interstellar clouds, and is ubiquitous in the ISM. Moreover, the chemistry of HCN radiolysis products such as CN- may be essential to understand of the formation of amino acids [3] and purine DNA bases. Here we present new results on the irradiation of multilayer films of CO2 and NH3 with 70 eV electrons, leading to CN bond formations. The electron stimulated desorption (ESD) yields of cations and anions are recorded as a function of electron fluence. The prompt desorption of cationic reaction/scattering products [4], is observed at low fluence (~4x1013 electrons/cm2). Detected ions include C2+, C2O2+, C2O+, CO3+, C2O3+ or CO4+ from pure CO2, and N+, NH+, NH2+, NH3+, NH4+, N2+, N2H+ from pure NH3, and NO+, NOH+ from CO2/NH3 mixtures. Most saliently, increasing signals of negative ion products desorbing during prolonged irradiation of CO2/NH3 films included C2-, C2H-, C2H2-, as well as CN-, HCN- and H2CN-. The identification of particular product ions was accomplished by using 13CO2 and 15NH3 isotopes. The chemistry induced by electrons in pure films of CO2 and NH3 and mixtures with composition ratios (3:1), (1:1), and (1:3), was also studied by X-ray photoelectron spectroscopy (XPS). Irradiation of CO2/NH3 mixed films at 22 K produces species containing the following bonds/functional groups identified by XPS: C=O, O-H, C-C, C-O, C=N and N=O. (This work has been funded by NSERC).

Calpain Determines the Propensity of Adult Hippocampal Neural Stem Cells to Autophagic Cell Death Following Insulin Withdrawal.

Science.gov (United States)

Chung, Kyung Min; Park, Hyunhee; Jung, Seonghee; Ha, Shinwon; Yoo, Seung-Jun; Woo, Hanwoong; Lee, Hyang Ju; Kim, Seong Who; Kim, Eun-Kyoung; Moon, Cheil; Yu, Seong-Woon

2015-10-01

Programmed cell death (PCD) has significant effects on the function of neural stem cells (NSCs) during brain development and degeneration. We have previously reported that adult rat hippocampal neural stem (HCN) cells underwent autophagic cell death (ACD) rather than apoptosis following insulin withdrawal despite their intact apoptotic capabilities. Here, we report a switch in the mode of cell death in HCN cells with calpain as a critical determinant. In HCN cells, calpain 1 expression was barely detectable while calpain 2 was predominant. Inhibition of calpain in insulin-deprived HCN cells further augmented ACD. In contrast, expression of calpain 1 switched ACD to apoptosis. The proteasome inhibitor lactacystin blocked calpain 2 degradation and elevated the intracellular Ca(2+) concentration. In combination, these effects potentiated calpain activity and converted the mode of cell death to apoptosis. Our results indicate that low calpain activity, due to absence of calpain 1 and degradation of calpain 2, results in a preference for ACD over apoptosis in insulin-deprived HCN cells. On the other hand, conditions leading to high calpain activity completely switch the mode of cell death to apoptosis. This is the first report on the PCD mode switching mechanism in NSCs. The dynamic change in calpain activity through the proteasome-mediated modulation of the calpain and intracellular Ca(2+) levels may be the critical contributor to the demise of NSCs. Our findings provide a novel insight into the complex mechanisms interconnecting autophagy and apoptosis and their roles in the regulation of NSC death. © 2015 AlphaMed Press.

PHYSICO-CHEMICAL CHARACTERISTICS OF TRIBAL BEAN (Canavalia virosa AND ITS ALTERNATIVE TOFU AND TEMPEH FOOD PRODUCTS

Directory of Open Access Journals (Sweden)

Titiek F. Djaafar

2013-05-01

Full Text Available Increasing price of soybean becomes a serious problem for producers of traditional foods such as tempeh and tofu. These traditional foods are important protein sources for many Indonesian people. Tribal bean (Canavalia virosa could be used as a substitution of soybean for tempeh and tofu processing. This study aimed to determine physico-chemical characteristics of tribal bean and its products such as tofu and tempeh. Tribal bean old pods were peeled manually in the Postharvest and Agricultural Machinery Laboratory of the Yogyakarta AIAT. The peeled seeds were dried until 10% water content and their epidermis were removed mechanically by using an abrasive peeler to produce yellowish clean peeled beans. The beans were analyzed physically and chemically using the standard prosedure. Since the tribal bean seeds contained high HCN, to minimize HCN content the beans were presoaked for 48 hours in water. The beans were then mixed with soybean at a ratio of 50:50 or 25:75 and processed for making tempeh and tofu using traditional method. Physicochemical and organoleptic characteristics of the tribal bean tempe and tofu were analysed, involving organoleptic test with hedonic method, texture, as well as water, ash, protein and crude fiber contents. The results showed that tribal bean contained protein (37.30%, essential amino acids, minerals and fiber (3.1%, and a toxic substance HCN. Presoaking the beans in water for 48 hours significantly reduced HCN content by 98.51%, from 1334 ppm. Tofu made of a mixture of tribal bean and soybean at a ratio of 25:75 plus 2% rice vinegar as a coagulant has a white color and normal flavor appearances, and was accepted by panelists. The tribal bean tempeh contained 78.1% water, 1.21% ash, 8.14% protein, 3.1% crude fiber, and 44 ppm HCN. Tempeh made of a mixture of tribal bean and soybean at ratios of 50:50 and 25:75 showed good characters (flavor, taste, color, and texture and panelist acceptance, as well as nutrition

The role of an ancestral hyperpolarization-activated cyclic nucleotide-gated K+ channel in branchial acid-base regulation in the green crab, Carcinus maenas.

Science.gov (United States)

Fehsenfeld, Sandra; Weihrauch, Dirk

2016-03-01

Numerous electrophysiological studies on branchial K(+) transport in brachyuran crabs have established an important role for potassium channels in osmoregulatory ion uptake and ammonia excretion in the gill epithelium of decapod crustaceans. However, hardly anything is known of the actual nature of these channels in crustaceans. In the present study, the identification of a hyperpolarization-activated cyclic nucleotide-gated potassium channel (HCN) in the transcriptome of the green crab Carcinus maenas and subsequent performance of quantitative real-time PCR revealed the ubiquitous expression of this channel in this species. Even though mRNA expression levels in the cerebral ganglion were found to be approximately 10 times higher compared with all other tissues, posterior gills still expressed significant levels of HCN, indicating an important role for this transporter in branchial ion regulation. The relatively unspecific K(+)-channel inhibitor Ba(2+), as well as the HCN-specific blocker ZD7288, as applied in gill perfusion experiments and electrophysiological studies employing the split gill lamellae revealed the presence of at least two different K(+)/NH4(+)-transporting structures in the branchial epithelium of C. maenas. Furthermore, HCN mRNA levels in posterior gill 7 decreased significantly in response to the respiratory or metabolic acidosis that was induced by acclimation of green crabs to high environmental PCO2 and ammonia, respectively. Consequently, the present study provides first evidence that HCN-promoted NH4(+) epithelial transport is involved in both branchial acid-base and ammonia regulation in an invertebrate. © 2016. Published by The Company of Biologists Ltd.

N2 O A greenhouse gas released from the combustion of coals in fluidized beds

International Nuclear Information System (INIS)

Boavida, D.; Lobo, L. S.; Gulyurtlu, I.; Cabrita, I.

1996-01-01

This paper discusses the results of the experimental work investigating the formation of N-2 O and NO during fluidized bed combustion of coals, and of chars and volatiles produced from the pyrolysis of these coals. Ammonia (N H 3 ) and hydrogen cyanide (HCN) are shown to play important roles as gas phase precursors of both NO and N 2 O. The conversion of fuel-N through N H 3 and HCN to N 2 O and NO was studied using a fluidized bed combustor in the temperature range between 973 K and 1273 K, for two different coals. The results suggest that the principal contribution to N 2 O emission Originated from volatile-N, however, char-N could also have an important role, depending upon the temperature. 1 fig., 8 tabs

High-pass filtering of input signals by the Ih current in a non-spiking neuron, the retinal rod bipolar cell.

Directory of Open Access Journals (Sweden)

Lorenzo Cangiano

Full Text Available Hyperpolarization-activated cyclic nucleotide-sensitive (HCN channels mediate the I(f current in heart and I(h throughout the nervous system. In spiking neurons I(h participates primarily in different forms of rhythmic activity. Little is known, however, about its role in neurons operating with graded potentials as in the retina, where all four channel isoforms are expressed. Intriguing evidence for an involvement of I(h in early visual processing are the side effects reported, in dim light or darkness, by cardiac patients treated with HCN inhibitors. Moreover, electroretinographic recordings indicate that these drugs affect temporal processing in the outer retina. Here we analyzed the functional role of HCN channels in rod bipolar cells (RBCs of the mouse. Perforated-patch recordings in the dark-adapted slice found that RBCs exhibit I(h, and that this is sensitive to the specific blocker ZD7288. RBC input impedance, explored by sinusoidal frequency-modulated current stimuli (0.1-30 Hz, displays band-pass behavior in the range of I(h activation. Theoretical modeling and pharmacological blockade demonstrate that high-pass filtering of input signals by I(h, in combination with low-pass filtering by passive properties, fully accounts for this frequency-tuning. Correcting for the depolarization introduced by shunting through the pipette-membrane seal, leads to predict that in darkness I(h is tonically active in RBCs and quickens their responses to dim light stimuli. Immunohistochemistry targeting candidate subunit isoforms HCN1-2, in combination with markers of RBCs (PKC and rod-RBC synaptic contacts (bassoon, mGluR6, Kv1.3, suggests that RBCs express HCN2 on the tip of their dendrites. The functional properties conferred by I(h onto RBCs may contribute to shape the retina's light response and explain the visual side effects of HCN inhibitors.

CARBON CHEMISTRY IN THE ENVELOPE OF VY CANIS MAJORIS: IMPLICATIONS FOR OXYGEN-RICH EVOLVED STARS

International Nuclear Information System (INIS)

Ziurys, L. M.; Tenenbaum, E. D.; Pulliam, R. L.; Woolf, N. J.; Milam, S. N.

2009-01-01

Observations of the carbon-bearing molecules CO, HCN, CS, HNC, CN, and HCO + have been conducted toward the circumstellar envelope of the oxygen-rich red supergiant star, VY Canis Majoris (VY CMa), using the Arizona Radio Observatory (ARO). CO and HCN were also observed toward the O-rich shells of NML Cyg, TX Cam, IK Tau, and W Hya. Rotational transitions of these species at 1 mm, 0.8 mm, and 0.4 mm were measured with the ARO Submillimeter Telescope, including the J = 6 → 5 line of CO at 691 GHz toward TX Cam and W Hya. The ARO 12 m was used for 2 mm and 3 mm observations. Four transitions were observed for HCO + in VY CMa, the first definitive identification of this ion in a circumstellar envelope. Molecular line profiles from VY CMa are complex, indicating three separate outflows: a roughly spherical flow and separate red- and blueshifted winds, as suggested by earlier observations. Spectra from the other sources appear to trace a single outflow component. The line data were modeled with a radiative transfer code to establish molecular abundances relative to H 2 and source distributions. Abundances for CO derived for these objects vary over an order of magnitude, f ∼ 0.4-5 x 10 -4 , with the lower values corresponding to the supergiants. For HCN, a similar range in abundance is found (f ∼ 0.9-9 x 10 -6 ), with no obvious dependence on the mass-loss rate. In VY CMa, HCO + is present in all three outflows with f ∼ 0.4-1.6 x 10 -8 and a spatial extent similar to that of CO. HNC is found only in the red- and blueshifted components with [HCN]/[HNC] ∼ 150-190, while [CN]/[HCN] ∼ 0.01 in the spherical flow. All three velocity components are traced in CS, which has a confined spatial distribution and f ∼ 2-6 x 10 -7 . These observations suggest that carbon-bearing molecules in O-rich shells are produced by a combination of photospheric shocks and photochemistry. Shocks may play a more prominent role in the supergiants because of their macroturbulent

Carbon Chemistry in the Envelope of VY Canis Majoris: Implications for Oxygen-Rich Evolved Stars

Science.gov (United States)

Ziurys, L. M.; Tenenbaum, E. D.; Pulliam, R. L.; Woolf, N. J.; Milam, S. N.

2009-04-01

Observations of the carbon-bearing molecules CO, HCN, CS, HNC, CN, and HCO+ have been conducted toward the circumstellar envelope of the oxygen-rich red supergiant star, VY Canis Majoris (VY CMa), using the Arizona Radio Observatory (ARO). CO and HCN were also observed toward the O-rich shells of NML Cyg, TX Cam, IK Tau, and W Hya. Rotational transitions of these species at 1 mm, 0.8 mm, and 0.4 mm were measured with the ARO Submillimeter Telescope, including the J = 6 → 5 line of CO at 691 GHz toward TX Cam and W Hya. The ARO 12 m was used for 2 mm and 3 mm observations. Four transitions were observed for HCO+ in VY CMa, the first definitive identification of this ion in a circumstellar envelope. Molecular line profiles from VY CMa are complex, indicating three separate outflows: a roughly spherical flow and separate red- and blueshifted winds, as suggested by earlier observations. Spectra from the other sources appear to trace a single outflow component. The line data were modeled with a radiative transfer code to establish molecular abundances relative to H2 and source distributions. Abundances for CO derived for these objects vary over an order of magnitude, f ~ 0.4-5 × 10-4, with the lower values corresponding to the supergiants. For HCN, a similar range in abundance is found (f ~ 0.9-9 × 10-6), with no obvious dependence on the mass-loss rate. In VY CMa, HCO+ is present in all three outflows with f ~ 0.4-1.6 × 10-8 and a spatial extent similar to that of CO. HNC is found only in the red- and blueshifted components with [HCN]/[HNC] ~ 150-190, while [CN]/[HCN] ~ 0.01 in the spherical flow. All three velocity components are traced in CS, which has a confined spatial distribution and f ~ 2-6 × 10-7. These observations suggest that carbon-bearing molecules in O-rich shells are produced by a combination of photospheric shocks and photochemistry. Shocks may play a more prominent role in the supergiants because of their macroturbulent velocities.

Dense gas and star formation in individual Giant Molecular Clouds in M31

Science.gov (United States)

Viaene, S.; Forbrich, J.; Fritz, J.

2018-04-01

Studies both of entire galaxies and of local Galactic star formation indicate a dependency of a molecular cloud's star formation rate (SFR) on its dense gas mass. In external galaxies, such measurements are derived from HCN(1-0) observations, usually encompassing many Giant Molecular Clouds (GMCs) at once. The Andromeda galaxy (M31) is a unique laboratory to study the relation of the SFR and HCN emission down to GMC scales at solar-like metallicities. In this work, we correlate our composite SFR determinations with archival HCN, HCO+, and CO observations, resulting in a sample of nine reasonably representative GMCs. We find that, at the scale of individual clouds, it is important to take into account both obscured and unobscured star formation to determine the SFR. When correlated against the dense-gas mass from HCN, we find that the SFR is low, in spite of these refinements. We nevertheless retrieve an SFR-dense-gas mass correlation, confirming that these SFR tracers are still meaningful on GMC scales. The correlation improves markedly when we consider the HCN/CO ratio instead of HCN by itself. This nominally indicates a dependency of the SFR on the dense-gas fraction, in contradiction to local studies. However, we hypothesize that this partly reflects the limited dynamic range in dense-gas mass, and partly that the ratio of single-pointing HCN and CO measurements may be less prone to systematics like sidelobes. In this case, the HCN/CO ratio would importantly be a better empirical measure of the dense-gas content itself.

Some new results on shock chemistry in IC 443

International Nuclear Information System (INIS)

DeNoyer, L.K.; Frerking, M.A.

1981-01-01

We have made new observations of CO, 13 CO, SiO, SO, H 2 CO, HCO + , N 2 H + , CS, OCS, HCN, and OH in the shocked clouds of IC 443. At position IC 443 B, we find (a) the shocked CO is optically thin, (b) the HCO + /CO abundance ratio is 4--9 x 10 -4 , a tenfold enhancement over normal interstellar clouds, (c) HCN/CO = 1--3 x 10 -4 and CS/CO = 2--3 x 10 -4 , consistent with abundances found in ordinary clouds, (d) no enhancements of SO or SiO as occur in Orion KL, (e) optically thin preshock OH, confirming a hundredfold enhancement of OH/CO in the shock, and (f) an OH main line anomaly, with T/sub ex/(1667)>T/sub ex/(1665) in the shocked region

Meta-path based heterogeneous combat network link prediction

Science.gov (United States)

Li, Jichao; Ge, Bingfeng; Yang, Kewei; Chen, Yingwu; Tan, Yuejin

2017-09-01

The combat system-of-systems in high-tech informative warfare, composed of many interconnected combat systems of different types, can be regarded as a type of complex heterogeneous network. Link prediction for heterogeneous combat networks (HCNs) is of significant military value, as it facilitates reconfiguring combat networks to represent the complex real-world network topology as appropriate with observed information. This paper proposes a novel integrated methodology framework called HCNMP (HCN link prediction based on meta-path) to predict multiple types of links simultaneously for an HCN. More specifically, the concept of HCN meta-paths is introduced, through which the HCNMP can accumulate information by extracting different features of HCN links for all the six defined types. Next, an HCN link prediction model, based on meta-path features, is built to predict all types of links of the HCN simultaneously. Then, the solution algorithm for the HCN link prediction model is proposed, in which the prediction results are obtained by iteratively updating with the newly predicted results until the results in the HCN converge or reach a certain maximum iteration number. Finally, numerical experiments on the dataset of a real HCN are conducted to demonstrate the feasibility and effectiveness of the proposed HCNMP, in comparison with 30 baseline methods. The results show that the performance of the HCNMP is superior to those of the baseline methods.

Reduced Hyperpolarization-Activated Current Contributes to Enhanced Intrinsic Excitability in Cultured Hippocampal Neurons from PrP(-/-) Mice.

Science.gov (United States)

Fan, Jing; Stemkowski, Patrick L; Gandini, Maria A; Black, Stefanie A; Zhang, Zizhen; Souza, Ivana A; Chen, Lina; Zamponi, Gerald W

2016-01-01

Genetic ablation of cellular prion protein (PrP(C)) has been linked to increased neuronal excitability and synaptic activity in the hippocampus. We have previously shown that synaptic activity in hippocampi of PrP-null mice is increased due to enhanced N-methyl-D-aspartate receptor (NMDAR) function. Here, we focused on the effect of PRNP gene knock-out (KO) on intrinsic neuronal excitability, and in particular, the underlying ionic mechanism in hippocampal neurons cultured from P0 mouse pups. We found that the absence of PrP(C) profoundly affected the firing properties of cultured hippocampal neurons in the presence of synaptic blockers. The membrane impedance was greater in PrP-null neurons, and this difference was abolished by the hyperpolarization-activated cyclic nucleotide-gated (HCN) channel blocker ZD7288 (100 μM). HCN channel activity appeared to be functionally regulated by PrP(C). The amplitude of voltage sag, a characteristic of activating HCN channel current (I h), was decreased in null mice. Moreover, I h peak current was reduced, along with a hyperpolarizing shift in activation gating and slower kinetics. However, neither HCN1 nor HCN2 formed a biochemical complex with PrP(C). These results suggest that the absence of PrP downregulates the activity of HCN channels through activation of a cell signaling pathway rather than through direct interactions. This in turn contributes to an increase in membrane impedance to potentiate neuronal excitability.

Solid-State Photochemistry as a Formation Mechanism for Titan's Stratospheric C4N2 Ice Clouds

Science.gov (United States)

Anderson, C. M.; Samuelson, R. E.; Yung, Y. L.; McLain, J. L.

2016-01-01

We propose that C4N2 ice clouds observed in Titan's springtime polar stratosphere arise due to solid-state photochemistry occurring within extant ice cloud particles of HCN-HC3N mixtures. This formation process resembles the halogen-induced ice particle surface chemistry that leads to condensed nitric acid trihydrate (NAT) particles and ozone depletion in Earth's polar stratosphere. As our analysis of the Cassini Composite Infrared Spectrometer 478 per centimeter ice emission feature demonstrates, this solid-state photochemistry mechanism eliminates the need for the relatively high C4N2 saturation vapor pressures required (even though they are not observed) when the ice is produced through the usual procedure of direct condensation from the vapor.

Glycine metabolism by Pseudomonas aeruginosa: hydrogen cyanide biosynthesis

International Nuclear Information System (INIS)

Castric, P.A.

1977-01-01

Hydrogen cyanide (HCN) production by Pseudomonas aeruginosa in a synthetic medium is stimulated by the presence of glycine. Methionine enhances this stimulation but will not substitute for glycine as a stimulator of cyanogenesis. Threonine and phenylalanine are effective substitutes for glycine in the stimulation of HCN production. Glycine, threonine, and serine are good radioisotope precursors of HCN, but methionine and phenylalanine are not. Cell extracts of P. aeruginosa convert [ 14 C]threonine to [ 14 C]glycine. H14CN is produced with low dilution of label from either [1- 14 C]glycine or [2- 14 C]glycine, indicating a randomization of label either in the primary or secondary metabolism of glycine. When whole cells were fed [1,2- 14 C]glycine, cyanide and bicarbonate were the only radioactive extracellular products observed

Key intermediates in nitrogen transformation during microwave pyrolysis of sewage sludge: a protein model compound study.

Science.gov (United States)

Zhang, Jun; Tian, Yu; Cui, Yanni; Zuo, Wei; Tan, Tao

2013-03-01

The nitrogen transformations with attention to NH3 and HCN were investigated at temperatures of 300-800°C during microwave pyrolysis of a protein model compound. The evolution of nitrogenated compounds in the char, tar and gas products were conducted. The amine-N, heterocyclic-N and nitrile-N compounds were identified as three important intermediates during the pyrolysis. NH3 and HCN were formed with comparable activation energies competed to consume the same reactive substances at temperatures of 300-800°C. The deamination and dehydrogenation of amine-N compounds from protein cracking contributed to the formation of NH3 (about 8.9% of Soy-N) and HCN (6.6%) from 300 to 500°C. The cracking of nitrile-N and heterocyclic-N compounds from the dehydrogenation and polymerization of amine-N generated HCN (13.4%) and NH3 (31.3%) between 500 and 800°C. It might be able to reduce the HCN and NH3 emissions through controlling the intermediates production at temperatures of 500-800°C. Copyright © 2013 Elsevier Ltd. All rights reserved.

Formation of nitrogen-containing compounds during slow pyrolysis and oxidation of petroleum coke

Energy Technology Data Exchange (ETDEWEB)

Furimsky, E.; Ohtsuka, Y. [IMAF Group, Ottawa, ON (Canada)

1997-09-01

The petroleum coke from a fluid coking process was pyrolyzed in helium and oxidized in 1% and 4% O{sub 2} and in air, with the aim to determine N-containing compounds such as HCN, NH{sub 3}, NO, and N{sub 2}O. The experiments were performed with and without limestone. NO was the major product during all oxidation runs. N{sub 2}O was formed only in air. In this case, N{sub 2}O formation was delayed when compared with that of NO. The addition of limestone decreased formation of HCN and increased that of NH{sub 3}, whereas NO formation was least affected. 36 refs., 8 figs., 6 tabs.

Formation of nitrogen compounds from nitrogen-containing rings during oxidative regeneration of spent hydroprocessing catalysts

Energy Technology Data Exchange (ETDEWEB)

Furimsky, E.; Nielsen, M.; Jurasek, P. [CANMET, Ottawa, ON (Canada). Energy Research Laboratories

1995-05-01

Commercial CoMo and NiMo catalysts in an oxidic and sulfided form and a {gamma}-alumina were deposited with pyrrole, pyridine, and quinoline. The deposited catalysts and two spent hydroprocessing catalysts were pyrolyzed and oxidized under conditions typical of regeneration of hydroprocessing catalysts. The formation of NH{sub 3} and HCN, as well as selected cases of N{sub 2}O and NO, was monitored during the experiments. NH{sub 3} and HCN were formed during pyrolysis of pyrrole-deposited catalysts whereas only NH{sub 3} was formed during that of pyridine-and quinoline-deposited catalysts. For all deposited catalysts, both NH{sub 3} and HCN were formed during temperature programmed oxidation in 2% O{sub 2}. For spent catalysts, a small amount of N{sub 2}O was formed in 2 and 4% O{sub 2}. For pyrrole-deposited catalysts, large yields of N{sub 2}O were formed in 4% O{sub 2}. Under the same conditions, N{sub 2}O yields for pyridine- and quinoline-deposited catalysts were very small. 13 refs., 12 figs., 6 tabs.

Investigation of the formation of hydrogen cyanide in the coking of kuzbass coal. [Magnitogorsk Integrated Iron and Steel Works-USSR

Energy Technology Data Exchange (ETDEWEB)

Grigorev, N.P.; Zhilyaev, Yu.A.; Akulov, P.V.

1981-01-01

The experiments were performed using equipment which practically excluded deep pyrolysis of the vapor gas products. The hydrogen cyanide was recovered with 0.1 N caustic soda solution in the temperature range of 500 to 1000/sup 0/C. The HCN concentration was measured photometrically by the acid derivative formed as a result of the reaction of the cyanide radical with the barbituric acid amines. The dynamics of the HCN yield were investigated as a function of the heating rate, the degree of comminuition of the coal types and the charge. 2/3 of the HCN is formed as a result of pyrolysis of the vapor-gas products and 1/3 is attributed to the thermochemical conversion of organic matter.

Solid-phase thermal decomposition of 2,4-dinitroimidazole (2,4-DNI)

Energy Technology Data Exchange (ETDEWEB)

Minier, L.; Behrens, R. Jr. [Rome Astronomical Observatory (Italy). Space Physics Research Center; Bulusu, S. [Army Armament Research and Development Command, Dover, NJ (United States). Energetic Materials Div.

1996-12-31

The solid-phase thermal decomposition of the insensitive energetic nitroaromatic heterocycle 2,4-dinitroimidazole (2,4-DNI: mp 265--274C) is studied utilizing simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) between 200 and 247C. The pyrolysis products have been identified using perdeuterated and {sup 15}N-labeled isotopomers. The products consist of low molecular-weight gases and a thermally stable solid residue. The major gaseous products are NO, CO{sub 2}, CO, N{sub 2}, HNCO and H{sub 2}O. Minor gaseous products are HCN, C{sub 2}N{sub 2}, NO{sub 2}, C{sub 3}H{sub 4}N{sub 2}, C{sub 3}H{sub 3}N{sub 3}O and NH{sub 3}. The elemental formula of the residue is C{sub 2}HN{sub 2}O and FTIR analysis suggests that it is polyurea- and polycarbamate-like in nature. Rates of formation of the gaseous products and their respective quantities have been determined for a typical isothermal decomposition experiment at 235C. The temporal behaviors of the gas formation rates indicate that the overall decomposition is characterized by a sequence of four events; (1) an early decomposition period induced by impurities and water, (2) an induction period where C0{sub 2} and NO are the primary products formed at relatively constant rates, (3) an autoacceleratory period that peaks when the sample is depleted and (4) a final period in which the residue decomposes. Arrhenius parameters for the induction period are E{sub a} = 46.9 {plus_minus} 0.7 kcal/mol and Log(A) = 16.3 {plus_minus} 0.3. Decomposition pathways that are consistent with the data are presented.

A comparative study of nitrogen conversion during pyrolysis of coconut fiber, its corresponding biochar and their blends with lignite.

Science.gov (United States)

Liu, Zhengang; Balasubramanian, Rajasekhar

2014-01-01

In the present study, the conversion of fuel-N to HCN and NH3 was investigated during rapid pyrolysis of raw biomass (coconut fiber), its corresponding biochar and their blends with lignite within a temperature range of 600-900°C. The results showed that the raw biomass and the biochar showed totally different nitrogen partitioning between NH3 and HCN. HCN was the dominant nitrogen pollutant from pyrolysis of raw biomass, while for the biochar pyrolysis the yield of NH3 was slightly higher than that of HCN. Synergistic interactions occurred within both raw biomass/lignite and biochar/lignite blends, especially for the biochar/lignite blend, and resulted in reduced yields of HCN and NH3, decreased the total nitrogen percentage retained in the char and promoted harmless N2 formation. These findings suggest that biochar/lignite co-firing for energy production may have the enhanced benefit of reduced emissions of nitrogen pollutants than raw biomass/lignite. Copyright © 2013 Elsevier Ltd. All rights reserved.

Summer 2012 Testing and Analysis of the Chemical Mixture Methodology -- Part I

Energy Technology Data Exchange (ETDEWEB)

Glantz, Clifford S.; Yu, Xiao-Ying; Coggin, Rebekah L.; Ponder, Lashaundra A.; Booth, Alexander E.; Petrocchi, Achille J.; Horn, Sarah M.; Yao, Juan

2012-07-01

This report presents the key findings made by the Chemical Mixture Methodology (CMM) project team during the first stage of their summer 2012 testing and analysis of the CMM. The study focused on answering the following questions: o What is the percentage of the chemicals in the CMM Rev 27 database associated with each Health Code Number (HCN)? How does this result influence the relative importance of acute HCNs and chronic HCNs in the CMM data set? o What is the benefit of using the HCN-based approach? Which Modes of Action and Target Organ Effects tend to be important in determining the HCN-based Hazard Index (HI) for a chemical mixture? o What are some of the potential issues associated with the current HCN-based approach? What are the opportunities for improving the performance and/or technical defensibility of the HCN-based approach? How would those improvements increase the benefit of using the HCN-based approach? o What is the Target Organ System Effect approach and how can it be used to improve upon the current HCN-based approach? How does the benefits users would derive from using the Target Organ System Approach compare to the benefits available from the current HCN-based approach?

Denitrogenation and desulphurization during hydropyrolysis of coal in H{sub 2}/Ar plasma jet

Energy Technology Data Exchange (ETDEWEB)

Bao, W.; Zhang, J.; Shen, S.; Cao, Q.; Lu, Y. [Taiyuan University of Technology, Taiyuan (China)

2007-03-15

The denitrogenation and desulphurization during hydropyrolysis of six Chinese coals were systematically investigated in H{sub 2}/Ar plasma jet. The results from experiments show that HCN is the main product of coal-N at high temperature. Only a low amount of NH{sub 3} is formed. Yield of HCN depends on coal types and coal feeding rate, but NH{sub 3} does not change obviously. Yields of HCN and NH{sub 3} decrease with the increase of oxygen contents in coal during hydropyrolysis in H{sub 2}/Ar plasma jet. The change of feeding rate affects the formation of H{sub 2}S from the conversion of coal-S. The mole ratios of n(N)/n(C) and n(S)/n(C) in all char samples are less than that of coal. The results suggest that hydropyrolysis in H{sub 2}/Ar plasma jet is an efficient method for denitrogenation and desulphurization. In the present experimental conditions, the denitrogenation and desulphurization percentages reach up to 50% and 55% for Yanzhou coal, respectively. Yima coal can reach up to 40% and 60%. 11 refs., 3 figs., 3 tabs.

SULFUR- AND SILICON-BEARING MOLECULES IN PLANETARY NEBULAE: THE CASE OF M2-48

Energy Technology Data Exchange (ETDEWEB)

Edwards, J. L.; Ziurys, L. M., E-mail: lziurys@email.arizona.edu [Department of Chemistry, The University of Arizona, P.O. Box 210041, Tucson, AZ 85721 (United States)

2014-10-20

Molecular-line observations of the bipolar planetary nebula (PN) M2-48 have been conducted using the Sub-Millimeter Telescope and the 12 m antenna of the Arizona Radio Observatory at 1, 2, and 3 mm. M2-48 is estimated to be ∼4800 yr old, midway through the PN evolutionary track. SiO and SO{sub 2} were detected in this source—the first identification of either molecule in a PN. CN, HCN, HNC, CS, SO, HCO{sup +}, N{sub 2}H{sup +}, and several {sup 13}C isotopologues such as {sup 13}CN, H{sup 13}CN, and H{sup 13}CO{sup +} were also observed toward this object. A radiative transfer analysis of multiple SiO transitions indicates a gas kinetic temperature of T {sub K} ∼ 55 K and a density of n(H{sub 2}) ∼ 9 × 10{sup 5} cm{sup –3} in M2-48, in agreement with previous CS and CO modeling. After CO, CN, and SO were found to be the most prevalent molecules in this nebula, with fractional abundances, relative to H{sub 2}, of f ∼ 3.8 × 10{sup –7} and 2.4 × 10{sup –7}, respectively. SO{sub 2} and HCN are also abundant, with f ∼ 1.2 × 10{sup –7}, indicating an [SO]/[SO{sub 2}] ratio of ∼2. Relatively high ion abundances were measured in M2-48 as well, with f ∼ 10{sup –7} for both HCO{sup +} and N{sub 2}H{sup +}. An [HCN]/[HNC] ratio of ∼2 was determined, as typically observed in other PNe, independent of age. The high abundances of SO and SO{sub 2}, along with the presence of SiO with f ∼ 2.9 × 10{sup –8}, suggest O/C > 1 in this source; furthermore, the prevalence of CN and N{sub 2}H{sup +} indicates nitrogen enrichment. The {sup 12}C/{sup 13}C ratio of ∼3 in the nebula was also established. These factors indicate hot-bottom burning occurred in the progenitor star of M2-48, suggesting an initial mass > 4 M {sub ☉}.

Spatially resolved chemistry in nearby galaxies. III. Dense molecular gas in the inner disk of the LIRG IRAS 04296+2923

Energy Technology Data Exchange (ETDEWEB)

Meier, David S. [Department of Physics, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801 (United States); Turner, Jean L. [Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095-1547 (United States); Beck, Sara C., E-mail: dmeier@nmt.edu, E-mail: turner@astro.ucla.edu, E-mail: sara@wise.tau.ac.il [Department of Physics and Astronomy, Tel Aviv University, 69978 Ramat Aviv (Israel)

2014-11-10

We present a survey of 3 mm molecular lines in IRAS 04296+2923, one of the brightest known molecular-line emitting galaxies, and one of the closest luminous infrared galaxies (LIRGs). Data are from the Owens Valley and CARMA millimeter interferometers. Species detected at ≲ 4'' resolution include C{sup 18}O, HCN, HCO{sup +}, HNC, CN, CH{sub 3}OH, and, tentatively, HNCO. Along with existing CO, {sup 13}CO, and radio continuum data, these lines constrain the chemical properties of the inner disk. Dense molecular gas in the nucleus fuels a star formation rate ≳10 M {sub ☉} yr{sup –1} and is traced by lines of HCN, HCO{sup +}, HNC, and CN. A correlation between HCN and star formation rate is observed on sub-kiloparsec scales, consistent with global relations. Toward the nucleus, CN abundances are similar to those of HCN, indicating emission comes from a collection (∼40-50) of moderate visual extinction, photon-dominated-region clouds. The CO isotopic line ratios are unusual: CO(1-0)/{sup 13}CO(1-0) and CO(1-0)/C{sup 18}O(1-0) line ratios are large toward the starburst, as is commonly observed in LIRGs, but farther out in the disk these ratios are remarkably low (≲ 3). {sup 13}CO/C{sup 18}O abundance ratios are lower than in Galactic clouds, possibly because the C{sup 18}O is enriched by massive star ejecta from the starburst. {sup 13}CO is underabundant relative to CO. Extended emission from CH{sub 3}OH indicates that dynamical shocks pervade both the nucleus and the inner disk. The unusual CO isotopologue ratios, the CO/HCN intensity ratio versus L {sub IR}, the HCN/CN abundance ratio, and the gas consumption time versus inflow rate all indicate that the starburst in IRAS 04296+2923 is in an early stage of development.

Studies of interstellar vibrationally-excited molecules

International Nuclear Information System (INIS)

Ziurys, L.M.; Snell, R.L.; Erickson, N.R.

1986-01-01

Several molecules thus far have been detected in the ISM in vibrationally-excited states, including H 2 , SiO, HC 3 N, and CH 3 CN. In order for vibrational-excitation to occur, these species must be present in unusually hot and dense gas and/or where strong infrared radiation is present. In order to do a more thorough investigation of vibrational excitation in the interstellar medium (ISM), studies were done of several mm-wave transitions originating in excited vibrational modes of HCN, an abundant interstellar molecule. Vibrationally-excited HCN was recently detected toward Orion-KL and IRC+10216, using a 12 meter antenna. The J=3-2 rotational transitions were detected in the molecule's lowest vibrational state, the bending mode, which is split into two separate levels, due to l-type doubling. This bending mode lies 1025K above ground state, with an Einstein A coefficient of 3.6/s. The J=3-2 line mode of HCN, which lies 2050K above ground state, was also observed toward IRC+10216, and subsequently in Orion-KL. Further measurements of vibrationally-excited HCN were done using a 14 meter telescope, which include the observations of the (0,1,0) and (0,2,0) modes towards Orion-KL, via their J=3-2 transitions at 265-267 GHz. The spectrum of the J=3-2 line in Orion taken with the 14 meter telescope, is shown, along with a map, which indicates that emission from vibrationally-excited HCN arises from a region probably smaller than the 14 meter telescope's 20 arcsec beam

Biological pacemakers in canines exhibit positive chronotropic response to emotional arousal

NARCIS (Netherlands)

Shlapakova, Iryna N.; Nearing, Bruce D.; Lau, David H.; Boink, Gerard J. J.; Danilo, Peter; Kryukova, Yelena; Robinson, Richard B.; Cohen, Ira S.; Rosen, Michael R.; Verrier, Richard L.

2010-01-01

Biological pacemakers based on the HCN2 channel isoform respond to beta-adrenergic and muscarinic stimulation, suggesting a capacity to respond to autonomic input. The purpose of this study was to investigate autonomic response to emotional arousal in canines implanted with murine HCN2-based

HNC IN PROTOPLANETARY DISKS

International Nuclear Information System (INIS)

Graninger, Dawn; Öberg, Karin I.; Qi, Chunhua; Kastner, Joel

2015-01-01

The distributions and abundances of small organics in protoplanetary disks are potentially powerful probes of disk physics and chemistry. HNC is a common probe of dense interstellar regions and the target of this study. We use the Submillimeter Array (SMA) to observe HNC 3–2 toward the protoplanetary disks around the T Tauri star TW Hya and the Herbig Ae star HD 163296. HNC is detected toward both disks, constituting the first spatially resolved observations of HNC in disks. We also present SMA observations of HCN 3–2 and IRAM 30 m observations of HCN and HNC 1–0 toward HD 163296. The disk-averaged HNC/HCN emission ratio is 0.1–0.2 toward both disks. Toward TW Hya, the HNC emission is confined to a ring. The varying HNC abundance in the TW Hya disk demonstrates that HNC chemistry is strongly linked to the disk physical structure. In particular, the inner rim of the HNC ring can be explained by efficient destruction of HNC at elevated temperatures, similar to what is observed in the ISM. However, to realize the full potential of HNC as a disk tracer requires a combination of high SNR spatially resolved observations of HNC and HCN and disk-specific HNC chemical modeling

HNC IN PROTOPLANETARY DISKS

Energy Technology Data Exchange (ETDEWEB)

Graninger, Dawn; Öberg, Karin I.; Qi, Chunhua [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Kastner, Joel, E-mail: dgraninger@cfa.harvard.edu [Center for Imaging Science, School of Physics and Astronomy, and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States)

2015-07-01

The distributions and abundances of small organics in protoplanetary disks are potentially powerful probes of disk physics and chemistry. HNC is a common probe of dense interstellar regions and the target of this study. We use the Submillimeter Array (SMA) to observe HNC 3–2 toward the protoplanetary disks around the T Tauri star TW Hya and the Herbig Ae star HD 163296. HNC is detected toward both disks, constituting the first spatially resolved observations of HNC in disks. We also present SMA observations of HCN 3–2 and IRAM 30 m observations of HCN and HNC 1–0 toward HD 163296. The disk-averaged HNC/HCN emission ratio is 0.1–0.2 toward both disks. Toward TW Hya, the HNC emission is confined to a ring. The varying HNC abundance in the TW Hya disk demonstrates that HNC chemistry is strongly linked to the disk physical structure. In particular, the inner rim of the HNC ring can be explained by efficient destruction of HNC at elevated temperatures, similar to what is observed in the ISM. However, to realize the full potential of HNC as a disk tracer requires a combination of high SNR spatially resolved observations of HNC and HCN and disk-specific HNC chemical modeling.

Submillimetric Spectroscopic Observations of Volatiles in Comet C-2004 Q2 (Machholz)

Science.gov (United States)

DeVal-Borro, M.; Hartogh, P.; Jarchow, C.; Rengel, M.; Villanueva, G. L.; Kueppers, M.; Biver, N.; Bockelee-Morvan, D.; Crovisier, J.

2012-01-01

Submillimeter spectroscopic observations of comets provide an important tool for understanding their chemical composition and enable a taxonomic classification. Aims. We aim to determine the production rates of several parent- and product volatiles and the C-12/C-13 isotopic carbon ratio in the long-period comet C/2004 Q2 (Machholz), which is likely to originate from the Oort Cloud. Methods. The line emission from several molecules in the coma was measured with high signal-to-noise ratio in January 2005 at heliocentric distance of 1.2 AU by means of high-resolution spectroscopic observations using the Submillimeter Telescope (SMT) at the Arizona Radio Observatory (ARO). Results. We have obtained production rates of several volatiles (CH3OH, HCN, H(sup 13)CN, HNC, H2CO, CO, and CS) by comparing the observed and simulated line-integrated intensities. We calculated the synthetic profiles using a radiative transfer code that includes collisions between neutrals and electrons, and the effects of radiative pumping of the fundamental vibrational levels by solar infrared radiation. Furthermore, multiline observations of the CH3OH J = 7-6 series allow us to estimate the rotational temperature using the rotation diagram technique. We find that the CH3OH population distribution of the levels sampled by these lines can be described by a rotational temperature of 40 +/- 3 K. Derived mixing ratios relative to hydrogen cyanide are CO/CH3OH/H2CO/CS/HNC/HC-13N/HCN= 30.9/24.6/4.8/0.57/0.031/0.013/1 assuming a pointing offset of 8" due to the uncertain ephemeris at the time of the observations and the telescope pointing error. Conclusions. The measured relative molecular abundances in C/2004 Q2 (Machholz) are between low- to typical values of those obtained in Oort Cloud comets, suggesting that it has visited the inner solar system previously and undergone thermal processing. The HNC/HCN abundance ratio of approx 3.1% is comparable to that found in other comets, accounting for the

Chemistry and structure of giant molecular clouds in energetic environments

Science.gov (United States)

Anderson, Crystal Nicole

2016-09-01

Throughout the years many studies on Galactic star formation have been conducted. This resulted in the idea that giant molecular clouds (GMCs) are hierarchical in nature with substructures spanning a large range of sizes. The physical processes that determine how molecular clouds fragment, form clumps/cores and then stars depends strongly on both recent radiative and mechanical feed- back from massive stars and, on longer term, from enhanced cooling due to the buildup of metals. Radiative and mechanical energy input from stellar populations can alter subsequent star formation over a large part of a galaxy and hence is relevant to the evolution of galaxies. Much of our knowledge of star formation on galaxy wide scales is based on scaling laws and other parametric descriptions. But to understand the overall evolution of star formation in galaxies we need to watch the feedback processes at work on giant molecular cloud (GMC) scales. By doing this we can begin to answer how strong feedback environments change the properties of the substructure in GMCs. Tests of Galactic star formation theory to other galaxies has been a challenging process due to the lack of resolution with current instruments. Thus, only the nearest galaxies allow us to resolve GMCs and their substructures. The Large Magellanic Cloud (LMC), is one of the closest low metallicity dwarf galaxies (D˜ 50 kpc) and is close enough that current instruments can resolve the sub- structure of its GMCs to molecular gas tracers (e.g. HCO+, HCN, HNC, CS, C2H, N2H+) detected in the LMC at 1.5-40 pc scales and in NGC 5253 at 40 pc scales. I then compare the molecular gas detections to the Central Molecular Zone in our Galaxy. Dense molecular gas was detected in all of the sources. For the regions in the LMC, molecular lines of CS, N2H+, C 2H, HNC, HCO+ and HCN were all detected in N159W and N113 while only HCN, HCO+, HNC, and C2H were detected in 30Dor-10. Toward NGC 5253 only HCO+, HCN, C2H and CS were detected. I

Temperatures and Species Concentration in Propellant Dark Zones via Fitting Infrared (IR) Spectral Absorption Data

National Research Council Canada - National Science Library

Vanderhoff, J

1997-01-01

.... Within this range, absorptions for HCN, H2O, N2O, CO, CO2, and CH4 have been detected through the use of a 1,024 element platinum silicide array detector with the ability to read complete spectra in 10 ms...

Characterization of the HCNCO complex and its radiation-induced transformation to HNCCO in cold media: an experimental and theoretical investigation.

Science.gov (United States)

Kameneva, Svetlana V; Tyurin, Daniil A; Feldman, Vladimir I

2017-09-13

The HCNCO complex and its X-ray induced transformation to HNCCO in solid noble gas (Ng) matrices (Ng = Ne, Ar, Kr, Xe) was first characterized by matrix isolation FTIR spectroscopy at 5 K. The HCNCO complex was obtained by deposition of HCN/CO/Ng gaseous mixtures. The assignment was based on extensive quantum chemical calculations at the CCSD(T) level of theory. The calculations predicted two computationally stable structures for HCNCO and three stable structures for HNCCO. However, only the most energetically favorable linear structures corresponding to the co-ordination between the H atom of HCN (HNC) and the C atom of CO have been found experimentally. The HCNCO complex demonstrates a considerable red shift of the H-C stretching vibrations (-24 to -38 cm -1 , depending on the matrix) and a blue shift of the HCN bending vibrations (+29 to +32 cm -1 ) with respect to that of the HCN monomer, while the C[double bond, length as m-dash]O stretching mode is blue-shifted by 15 to 20 cm -1 as compared to the CO monomer. The HNCCO complex reveals a strong red shift of the H-N bending (-77 to -118 cm -1 ) and a strong blue shift of the HNC bending mode (ca. +100 cm -1 ) as compared to the HNC monomer, whereas the C[double bond, length as m-dash]O stretching is blue-shifted by 24 to 29 cm -1 with respect to that of the CO monomer. The interaction energies were determined to be 1.01 and 1.87 kcal mol -1 for HCNCO and HNCCO, respectively. It was found that the formation of complexes with CO had a remarkable effect on the radiation-induced transformations of HCN. While the dissociation of HCN to H and CN is suppressed in complexes, the isomerization of HCN to HNC is strongly catalyzed by the complexation with CO. The astrochemical implications of the results are discussed.

DISK IMAGING SURVEY OF CHEMISTRY WITH SMA. II. SOUTHERN SKY PROTOPLANETARY DISK DATA AND FULL SAMPLE STATISTICS

International Nuclear Information System (INIS)

Oeberg, Karin I.; Qi Chunhua; Andrews, Sean M.; Espaillat, Catherine; Wilner, David J.; Fogel, Jeffrey K. J.; Bergin, Edwin A.; Pascucci, Ilaria; Kastner, Joel H.

2011-01-01

This is the second in a series of papers based on data from DISCS, a Submillimeter Array observing program aimed at spatially and spectrally resolving the chemical composition of 12 protoplanetary disks. We present data on six Southern sky sources-IM Lup, SAO 206462 (HD 135344b), HD 142527, AS 209, AS 205, and V4046 Sgr-which complement the six sources in the Taurus star-forming region reported previously. CO 2-1 and HCO + 3-2 emission are detected and resolved in all disks and show velocity patterns consistent with Keplerian rotation. Where detected, the emission from DCO + 3-2, N 2 H + 3-2, H 2 CO 3 03 - 2 02 and 4 14 - 3 13 , HCN 3-2, and CN 2 33/4/2 - 1 22/3/1 are also generally spatially resolved. The detection rates are highest toward the M and K stars, while the F star SAO 206462 has only weak CN and HCN emission, and H 2 CO alone is detected toward HD 142527. These findings together with the statistics from the previous Taurus disks support the hypothesis that high detection rates of many small molecules depend on the presence of a cold and protected disk midplane, which is less common around F and A stars compared to M and K stars. Disk-averaged variations in the proposed radiation tracer CN/HCN are found to be small, despite a two orders of magnitude range of spectral types and accretion rates. In contrast, the resolved images suggest that the CN/HCN emission ratio varies with disk radius in at least two of the systems. There are no clear observational differences in the disk chemistry between the classical/full T Tauri disks and transitional disks. Furthermore, the observed line emission does not depend on the measured accretion luminosities or the number of infrared lines detected, which suggests that the chemistry outside of 100 AU is not coupled to the physical processes that drive the chemistry in the innermost few AU.

Upregulation of Ih expressed in IB4-negative Aδ nociceptive DRG neurons contributes to mechanical hypersensitivity associated with cervical radiculopathic pain

Science.gov (United States)

Liu, Da-Lu; Lu, Na; Han, Wen-Juan; Chen, Rong-Gui; Cong, Rui; Xie, Rou-Gang; Zhang, Yu-Fei; Kong, Wei-Wei; Hu, San-Jue; Luo, Ceng

2015-01-01

Cervical radiculopathy represents aberrant mechanical hypersensitivity. Primary sensory neuron’s ability to sense mechanical force forms mechanotransduction. However, whether this property undergoes activity-dependent plastic changes and underlies mechanical hypersensitivity associated with cervical radiculopathic pain (CRP) is not clear. Here we show a new CRP model producing stable mechanical compression of dorsal root ganglion (DRG), which induces dramatic behavioral mechanical hypersensitivity. Amongst nociceptive DRG neurons, a mechanically sensitive neuron, isolectin B4 negative Aδ-type (IB4− Aδ) DRG neuron displays spontaneous activity with hyperexcitability after chronic compression of cervical DRGs. Focal mechanical stimulation on somata of IB4- Aδ neuron induces abnormal hypersensitivity. Upregulated HCN1 and HCN3 channels and increased Ih current on this subset of primary nociceptors underlies the spontaneous activity together with neuronal mechanical hypersensitivity, which further contributes to the behavioral mechanical hypersensitivity associated with CRP. This study sheds new light on the functional plasticity of a specific subset of nociceptive DRG neurons to mechanical stimulation and reveals a novel mechanism that could underlie the mechanical hypersensitivity associated with cervical radiculopathy. PMID:26577374

The Composition of Comet C/2009 P1 (Garradd) from Infrared Spectroscopy: Evidence for an Oxygen-Rich Heritage?

Science.gov (United States)

DiSanti, M. A.; Bonev, B. P.; Villaneueva, G. L.; Paganini, L.; Mumma, M. J.; Charnley, S. B.; Keane, J. V.; Blake, G. A.; Boehnhardt, H.; Lippi, M.

2012-01-01

Comets retain relatively primitive icy material remaining from the epoch of Solar System formation, however the extent to which their ices are modified remains a key question in cometary science. One way to address this is to measure the relative abundances of primary (parent) volatiles in comets (i.e., those ices native to the nucleus). High-resolution (lambda/delta lambda greater than 10(exp 4)) infrared spectroscopy is a powerful tool for measuring parent volatiles in comets through their vibrational emissions in the approximately 3-5 micrometer region. With modern instrumentation on world-class telescopes, we can quantify a multitude of species (e.g., H2O, C2H2, CH4, C2H6, CO, H2CO, CH3OH, HCN, NH3), even in comets with modest gas production. In space environments, compounds of keen interest to astrobiology could originate from HCN and NH3 (leading to amino acids), H2CO (leading to sugars), or C2H6, and CH4 (suggested precursors of ethyl- and methylamine). Measuring the abundances of these precursor molecules and their variability among comets contributes to understanding the synthesis of the more complex prebiotic compounds.

THE DISK IMAGING SURVEY OF CHEMISTRY WITH SMA. I. TAURUS PROTOPLANETARY DISK DATA

International Nuclear Information System (INIS)

Oeberg, Karin I.; Qi Chunhua; Andrews, Sean M.; Espaillat, Catherine; Van Kempen, Tim A.; Wilner, David J.; Fogel, Jeffrey K. J.; Bergin, Edwin A.; Pascucci, Ilaria

2010-01-01

Chemistry plays an important role in the structure and evolution of protoplanetary disks, with implications for the composition of comets and planets. This is the first of a series of papers based on data from DISCS, a Submillimeter Array survey of the chemical composition of protoplanetary disks. The six Taurus sources in the program (DM Tau, AA Tau, LkCa 15, GM Aur, CQ Tau, and MWC 480) range in stellar spectral type from M1 to A4 and offer an opportunity to test the effects of stellar luminosity on the disk chemistry. The disks were observed in 10 different lines at ∼3'' resolution and an rms of ∼100 mJy beam -1 at ∼0.5 km s -1 . The four brightest lines are CO 2-1, HCO + 3-2, CN 2 33/4/2 - 1 22/3/1 , and HCN 3-2, and these are detected toward all sources (except for HCN toward CQ Tau). The weaker lines of CN 2 22 -1 11 , DCO + 3-2, N 2 H + 3-2, H 2 CO 3 03 -2 02 , and 4 14 -3 13 are detected toward two to three disks each, and DCN 3-2 only toward LkCa 15. CH 3 OH 4 21 -3 1 2 and c-C 3 H 2 are not detected. There is no obvious difference between the T Tauri and Herbig Ae sources with regard to CN and HCN intensities. In contrast, DCO + , DCN, N 2 H + , and H 2 CO are detected only toward the T Tauri stars, suggesting that the disks around Herbig Ae stars lack cold regions for long enough timescales to allow for efficient deuterium chemistry, CO freeze-out, and grain chemistry.

Storage and release of hydrogen cyanide in a chelicerate (Oribatula tibialis)

Science.gov (United States)

Brückner, Adrian; Raspotnig, Günther; Wehner, Katja; Meusinger, Reinhard; Norton, Roy A.; Heethoff, Michael

2017-01-01

Cyanogenesis denotes a chemical defensive strategy where hydrogen cyanide (HCN, hydrocyanic or prussic acid) is produced, stored, and released toward an attacking enemy. The high toxicity and volatility of HCN requires both chemical stabilization for storage and prevention of accidental self-poisoning. The few known cyanogenic animals are exclusively mandibulate arthropods (certain myriapods and insects) that store HCN as cyanogenic glycosides, lipids, or cyanohydrins. Here, we show that cyanogenesis has also evolved in the speciose Chelicerata. The oribatid mite Oribatula tibialis uses the cyanogenic aromatic ester mandelonitrile hexanoate (MNH) for HCN storage, which degrades via two different pathways, both of which release HCN. MNH is emitted from exocrine opisthonotal oil glands, which are potent organs for chemical defense in most oribatid mites. PMID:28289203

High-Resolution Infrared Spectroscopic Measurements of Comet 2PlEncke: Unusual Organic Composition and Low Rotational Temperatures

Science.gov (United States)

Radeva, Yana L.; Mumma, Michael J.; Villanueva, Geronimo L.; Bonev, Boncho P.; DiSanti, Michael A.; A'Hearn, Michael F.; Dello Russo, Neil

2013-01-01

We present high-resolution infrared spectroscopic measurements of the ecliptic comet 2P/Encke, observed on 4-6 Nov. 2003 during its close approach to the Earth, using the Near Infrared Echelle Spectrograph on the Keck II telescope. We present flux-calibrated spectra, production rates, and mixing ratios for H2O, CH3OH, HCN, H2CO, C2H2, C2H6, CH4 and CO. Comet 2P/Encke is a dynamical end-member among comets because of its short period of 3.3 years. Relative to "organics-normal" comets, we determined that 2PlEncke is depleted in HCN, H2CO, C2H2, C2H6, CH4 and CO, but it is enriched in CH3OH. We compared mixing ratios of these organic species measured on separate dates, and we see no evidence of macroscopic chemical heterogeneity in the nucleus of 2P/Encke, however, this conclusion is limited by sparse temporal sampling. The depleted abundances of most measured species suggest that 2P/Encke may have formed closer to the young Sun, before its insertion to the Kuiper belt, compared with "organics-normal" comets - as was previously suggested for other depleted comets (e.g. C/1999 S4 (LINEAR)). We measured very low rotational temperatures of 20 - 30 K for H2O, CH3OH and HCN in the near nucleus region of 2P/Encke, which correlate with one of the lowest cometary gas production rates (approx. 2.6 x 10(exp 27) molecules/s) measured thus far in the infrared. This suggests that we are seeing the effects of more efficient radiative cooling, insufficient collisional excitation, and/or inefficient heating by fast H-atoms (and icy grains) in the observed region of the coma. Its extremely short orbital period, very low gas production rate, and classification as an ecliptic comet, make 2PlEncke an important addition to our growing database, and contribute significantly to the establishment of a chemical taxonomy of comets.

OH megamasers: dense gas & the infrared radiation field

Science.gov (United States)

Huang, Yong; Zhang, JiangShui; Liu, Wei; Xu, Jie

2018-06-01

To investigate possible factors related to OH megamaser formation (OH MM, L_{H2O}>10L_{⊙}), we compiled a large HCN sample from all well-sampled HCN measurements so far in local galaxies and identified with the OH MM, OH kilomasers (L_{H2O}gas and the dense gas, respectively), we found that OH MM galaxies tend to have stronger HCN emission and no obvious difference on CO luminosity exists between OH MM and non-OH MM. This implies that OH MM formation should be related to the dense molecular gas, instead of the low-density molecular gas. It can be also supported by other facts: (1) OH MMs are confirmed to have higher mean molecular gas density and higher dense gas fraction (L_{HCN}/L_{CO}) than non-OH MMs. (2) After taking the distance effect into account, the apparent maser luminosity is still correlated with the HCN luminosity, while no significant correlation can be found at all between the maser luminosity and the CO luminosity. (3) The OH kMs tend to have lower values than those of OH MMs, including the dense gas luminosity and the dense gas fraction. (4) From analysis of known data of another dense gas tracer HCO^+, similar results can also be obtained. However, from our analysis, the infrared radiation field can not be ruled out for the OH MM trigger, which was proposed by previous works on one small sample (Darling in ApJ 669:L9, 2007). On the contrary, the infrared radiation field should play one more important role. The dense gas (good tracers of the star formation) and its surrounding dust are heated by the ultra-violet (UV) radiation generated by the star formation and the heating of the high-density gas raises the emission of the molecules. The infrared radiation field produced by the re-radiation of the heated dust in turn serves for the pumping of the OH MM.

Non-LTE models of Titan's upper atmosphere

Science.gov (United States)

Yelle, Roger V.

1991-01-01

Models for the thermal structure of Titan's upper atmosphere, between 0.1 mbar and 0.01 nbar are presented. The calculations include non-LTE heating/cooling in the rotation-vibration bands of CH4, C2H2, and C2H6, absorption of solar IR radiation in the near-IR bands of CH4 and subsequent cascading to the nu-4 band of CH4, absorption of solar EUV and UV radiation, thermal conduction and cooling by HCN rotational lines. Unlike earlier models, the calculated exospheric temperature agrees well with observations, because of the importance of HCN cooling. The calculations predict a well-developed mesopause with a temperature of 135-140 K at an altitude of approximately 600 km and pressure of about 0.1 microbar. The mesopause is at a higher pressure than predicted by earlier calculations because non-LTE radiative transfer in the rotation-vibration bands of CH4, C2H2, and C2H6 is treated in an accurate manner. The accuracy of the LTE approximation for source functions and heating rates is discussed.

The Compositional Evolution of C/2012 S1 (ISON) from Ground-Based High-Resolution Infrared Spectroscopy as Part of a Worldwide Observing Campaign

Science.gov (United States)

Russo, N. Dello; Vervack, R. J., Jr.; Kawakita, H.; Cochran, A.; McKay, A. J.; Harris, W. M.; Weaver, H.A.; Lisse, C. M.; DiSanti, M. A.; Kobayashi, H.

2015-01-01

Volatile production rates, relative abundances, rotational temperatures, and spatial distributions in the coma were measured in C/2012 S1 (ISON) using long-slit high-dispersion (lambda/delta lambda approximately 2.5 times 10 (sup 4)) infrared spectroscopy as part of a worldwide observing campaign. Spectra were obtained on Universal Time 2013 October 26 and 28 with NIRSPEC (Near Infrared Spectrometer) at the W.M. Keck Observatory, and Universal Time 2013 November 19 and 20 with CSHELL (Cryogenic Echelle Spectrograph) at the NASA IRTF (Infrared Telescope Facility). H2O was detected on all dates, with production rates increasing markedly from (8.7 plus or minus 1.5) times 10 (sup 27) molecules per second on October 26 (Heliocentric Distance = 1.12 Astronomical Units) to (3.7 plus or minus 0.4) times 10 (sup 29) molecules per second on November 20 (Heliocentric Distance = 0.43 Astronomical Units). Short-term variability of H2O production is also seen as observations on November 19 show an increase in H2O production rate of nearly a factor of two over a period of about 6 hours. C2H6, CH3OH and CH4 abundances in ISON (International Scientific Optical Network) are slightly depleted relative to H2O when compared to mean values for comets measured at infrared wavelengths. On the November dates, C2H2, HCN and OCS abundances relative to H2O appear to be within the range of mean values, whereas H2CO and NH3 were significantly enhanced. There is evidence that the abundances with respect to H2O increased for some species but not others between October 28 (Heliocentric Distance = 1.07 Astronomical Units) and November 19 (Heliocentric Distance = 0.46 Astronomical Units). The high mixing ratios of H2CO to CH3OH and C2H2 to C2H6 on November 19, and changes in the mixing ratios of some species with respect to H2O between October 28 to November 19, indicates compositional changes that may be the result of a transition from sampling radiation-processed outer layers in this dynamically

Testing the universality of the star-formation efficiency in dense molecular gas

Science.gov (United States)

Shimajiri, Y.; André, Ph.; Braine, J.; Könyves, V.; Schneider, N.; Bontemps, S.; Ladjelate, B.; Roy, A.; Gao, Y.; Chen, H.

2017-08-01

Context. Recent studies with, for example, Spitzer and Herschel have suggested that star formation in dense molecular gas may be governed by essentially the same "law" in Galactic clouds and external galaxies. This conclusion remains controversial, however, in large part because different tracers have been used to probe the mass of dense molecular gas in Galactic and extragalactic studies. Aims: We aimed to calibrate the HCN and HCO+ lines commonly used as dense gas tracers in extragalactic studies and to test the possible universality of the star-formation efficiency in dense gas (≳104 cm-3), SFEdense. Methods: We conducted wide-field mapping of the Aquila, Ophiuchus, and Orion B clouds at 0.04 pc resolution in the J = 1 - 0 transition of HCN, HCO+, and their isotopomers. For each cloud, we derived a reference estimate of the dense gas mass MHerschelAV > 8, as well as the strength of the local far-ultraviolet (FUV) radiation field, using Herschel Gould Belt survey data products, and estimated the star-formation rate from direct counting of the number of Spitzer young stellar objects. Results: The H13CO+(1-0) and H13CN(1-0) lines were observed to be good tracers of the dense star-forming filaments detected with Herschel. Comparing the luminosities LHCN and LHCO+ measured in the HCN and HCO+ lines with the reference masses MHerschelAV > 8, the empirical conversion factors αHerschel - HCN (=MHerschelAV > 8/LHCN) and αHerschel - HCO+ (=MHerschelAV > 8/LHCO+) were found to be significantly anti-correlated with the local FUV strength. In agreement with a recent independent study of Orion B by Pety et al., the HCN and HCO+ lines were found to trace gas down to AV ≳ 2. As a result, published extragalactic HCN studies must be tracing all of the moderate density gas down to nH2 ≲ 103 cm-3. Estimating the contribution of this moderate density gas from the typical column density probability distribution functions in nearby clouds, we obtained the following G0

Extension of raw milk quality through supplementation of hydrocyanic acid from fresh cassava peel in dairy cattle diet

Directory of Open Access Journals (Sweden)

Supreena Srisaikham

2017-12-01

Full Text Available The objective of this study was to evaluate the effects on the extension of raw milk quality through supplementation of hydrocyanic acid (HCN levels from fresh cassava peel (FCPe in dairy cattle diet by increasing the milk thiocyanate (SCN concentration and lactoperoxidase (LP activity. The sample was twenty-four Holstein Friesian crossbred lactating dairy cows, averaging 87±31 days in milk (DIM, 13.4±2.9 kg of milk and 397±52 kg body weight (BW. All cows were fed the control diet with 6.5 kg/d of 21% crude protein (CP concentrate and ad libitum grass silage (GS. The treatments groups were as follows: 1 the control diet for the 1st group, the 2nd group received the control diet supplemented with 400 g/d of FCPe (75 ppm HCN and the 3rd group received the control diet supplemented with 800 g/d of FCPe (150 ppm HCN. The results showed that 800 g/h/d FCPe enhanced the efficiency of LP activity in raw milk to reduce total bacterial count (TBC and coliform count (CC; therefore, 400 g/h/d FCPe can be used in the concentrate for lactating dairy cows.

Screening for acyanogenic somatic mutations in cassava (Manihot esculenta Crantz)

International Nuclear Information System (INIS)

Moh, C.C.

1976-01-01

By irradiating the young stem cuttings (6-8 months old wood) of a cassava cultivar, Japonesa, (Manihot esculenta Crantz) with an acute dose of 4 kR from a 60 CO source, it was found that in a number of cases, the induced mutant characters appeared in the whole R 1 plants or in large chimeric sectors. This result suggested that a cassava plant could develop from one or two initial cells in the shoot apex of a bud. This unusual biological response to radiation provides a great advantage for selection in mutation breeding. By using the sodium picrate method, 2676 leaves from 1338 R 1 plants irradiated with 4 kR were screened for hydrocyanic acid content (HCN). As compared with the control, some leaves had higher and some had lower HCN level, indicating that the radiation broadened the variability. Whether or not those R 1 plants producing a lower level of HCN in the leaves are truly a genetic mutant cannot be ascertained at present. Further screening of the selected R 1 plants in the subsequent vegetative propagation generations will help to distinguish whether they are genetic mutants. (author)

Is N-protonated hydrogen isocyanide, H2NC+, an observable interstellar species?

International Nuclear Information System (INIS)

DeFrees, D.J.; Binkley, J.S.; Frisch, M.J.; McLean, A.D.

1986-01-01

Ab initio molecular orbital theory is used to examine the singlet and triplet potential energy surfaces for the CH 2 N + system. The results confirm those of earlier studies which suggested that the singlet H 2 NC + isomer could be formed via the corresponding triplet isomer. Also, it is shown that the reaction HCN + +H 2 might lead to this metastable isomer without invoking the triplet species. The best test of the hypothesis that this molecule can be formed by gas phase, ion molecule reactions and may be an important precursor in the interstellar synthesis of HCN and HNC is to search for it in space. To this end, theoretical predictions are made of its rotational frequencies and its vibrational frequencies and intensities to serve as a guide to laboratory spectroscopists and radioastronomers

Shock Synthesis in the Atmosphere of Jupiter

Science.gov (United States)

Khare, B. N.; Sagan, C.; McDonald, G. D.; de Vanssay, E.; Borucki, W. J.; McKay, C. P.; Bernstein, M. P.; Hartman, T. G.; Lech, J.

1996-09-01

We have previously investigated an approximate simulation of the Jupiter troposphere at the 1 bar NH_3 cloud level using Laser Induced Plasma (LIP) for shock synthesis in a 84.62:13.3:1.07:1.01 H_2:He:CH_4:NH_3 gas mixture, and found by GC/MS that HCN is the most abundant product, more abundant than all the major product hydrocarbons (C_2H_6, C_2H_2, C_3H_8, and C_4H10) combined. Using purge and trap isolation techniques on the LIP gas mixture using two absorbent traps in tandem, thermal desorption GC/MS has revealed a large array of product molecules starting from simple hydrocarbons such as C_2H_2, C_2H_4, etc., simple nitriles such as HCN, CH_3CN, etc., to molecules up to C13 (e.g. C13H23N). Here we report the results of our more accurate simulation of Jupiter at the 5 bar level using LIP with a 88:11.7:0.2:0.1 H_2:He:CH_4:NH_3 mixture, for comparison with mass spectral data from the Galileo probe. We detect in this more acurate simulation of Jupiter many of the same compounds, such as HCN, dimethylaminoacetonitrile, and dimethylcyanamide, as in the previous lower dilution experiment. We will compare the present results with those from low-pressure continuous flow plasma discharge experiments (McDonald et al. 1992, al Icarus 99, 131). We will also discuss the relevance of our data in light of the significant discrepancies between standard models of the jovian atmosphere and the compositional data returned by the Galileo entry probe.

Towards quantitative SERS detection of hydrogen cyanide at ppb level for human breath analysis

Directory of Open Access Journals (Sweden)

Rikke Kragh Lauridsen

2015-09-01

Full Text Available Lung infections with Pseudomonas aeruginosa (PA is the most common cause of morbidity and mortality in cystic fibrosis (CF patients. Due to its ready adaptation to the dehydrated mucosa of CF airways, PA infections tend to become chronic, eventually killing the patient. Hydrogen cyanide (HCN at ppb level has been reported to be a PA biomarker. For early PA detection in CF children not yet chronically lung infected a non-invasive Surface-Enhanced Raman Spectroscopy (SERS-based breath nanosensor is being developed. The triple bond between C and N in cyanide, with its characteristic band at ∼2133 cm−1, is an excellent case for the SERS-based detection due to the infrequent occurrence of triple bonds in nature. For demonstration of direct HCN detection in the gas phase, a gold-coated silicon nanopillar substrate was exposed to 5 ppm HCN in N2. Results showed that HCN adsorbed on the SERS substrate can be consistently detected under different experimental conditions and up to 9 days after exposure. For detection of lower cyanide concentrations serial dilution experiments using potassium cyanide (KCN demonstrated cyanide quantification down to 1 μM in solution (corresponding to 18 ppb. Lower KCN concentrations of 10 and 100 nM (corresponding to 0.18 and 1.8 ppb produced SERS intensities that were relatively similar to the reference signal. Since HCN concentration in the breath of PA colonized CF children is reported to be ∼13.5 ppb, the detection of cyanide is within the required range. Keywords: Surface-Enhanced Raman Spectroscopy, Hydrogen cyanide, Pseudomonas aeruginosa, Cystic fibrosis, Breath analysis

Extremely organic-rich coma of comet C/2010 G2 (Hill) during its outburst in 2012

International Nuclear Information System (INIS)

Kawakita, Hideyo; Kobayashi, Hitomi; Russo, Neil Dello; Vervack, Ron Jr.; Weaver, Harold A.; DiSanti, Mike A.; Opitom, Cyrielle; Jehin, Emmanuel; Manfroid, Jean; Gillon, Michael; Cochran, Anita L.; Harris, Walter M.; Bockelée-Morvan, Dominique; Biver, Nicolas; Crovisier, Jacques; McKay, Adam J.

2014-01-01

We performed high-dispersion near-infrared spectroscopic observations of comet C/2010 G2 (Hill) at 2.5 AU from the Sun using NIRSPEC (R ≈ 25,000) at the Keck II Telescope on UT 2012 January 9 and 10, about a week after an outburst had occurred. Over the two nights of our observations, prominent emission lines of CH 4 and C 2 H 6 , along with weaker emission lines of H 2 O, HCN, CH 3 OH, and CO were detected. The gas production rate of CO was comparable to that of H 2 O during the outburst. The mixing ratios of CO, HCN, CH 4 , C 2 H 6 , and CH 3 OH with respect to H 2 O were higher than those for normal comets by a factor of five or more. The enrichment of CO and CH 4 in comet Hill suggests that the sublimation of these hypervolatiles sustained the outburst of the comet. Some fraction of water in the inner coma might exist as icy grains that were likely ejected from nucleus by the sublimation of hypervolatiles. Mixing ratios of volatiles in comet Hill are indicative of the interstellar heritage without significant alteration in the solar nebula.

Extremely organic-rich coma of comet C/2010 G2 (Hill) during its outburst in 2012

Energy Technology Data Exchange (ETDEWEB)

Kawakita, Hideyo; Kobayashi, Hitomi [Koyama Astronomical Observatory, Kyoto Sangyo University, Motoyama, Kamitamo, Kita, Kyoto 603-8555 (Japan); Russo, Neil Dello; Vervack, Ron Jr.; Weaver, Harold A. [The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723-6099 (United States); DiSanti, Mike A. [Goddard Center for Astrobiology, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Opitom, Cyrielle; Jehin, Emmanuel; Manfroid, Jean; Gillon, Michael [F. R. S.-FNRS, Institut d' Astrophysique et de Géophysique, Université de Liège, Allée du 6 août 17, B-4000 Liège (Belgium); Cochran, Anita L. [McDonald Observatory, 1 University Station C1402, Austin, TX 78712-0259 (United States); Harris, Walter M. [Department of Applied Sciences, University of California, One Shields Avenue, Davis, CA 95616 (United States); Bockelée-Morvan, Dominique; Biver, Nicolas; Crovisier, Jacques [LESIA, Observatoire de Paris, CNRS, UPMC, Université Paris-Diderot, 5 Place Jules Janssen, F-92195 Meudon (France); McKay, Adam J., E-mail: kawakthd@cc.kyoto-su.ac.jp [New Mexico State University, Las Cruces, NM 88001 (United States)

2014-06-20

We performed high-dispersion near-infrared spectroscopic observations of comet C/2010 G2 (Hill) at 2.5 AU from the Sun using NIRSPEC (R ≈ 25,000) at the Keck II Telescope on UT 2012 January 9 and 10, about a week after an outburst had occurred. Over the two nights of our observations, prominent emission lines of CH{sub 4} and C{sub 2}H{sub 6}, along with weaker emission lines of H{sub 2}O, HCN, CH{sub 3}OH, and CO were detected. The gas production rate of CO was comparable to that of H{sub 2}O during the outburst. The mixing ratios of CO, HCN, CH{sub 4}, C{sub 2}H{sub 6}, and CH{sub 3}OH with respect to H{sub 2}O were higher than those for normal comets by a factor of five or more. The enrichment of CO and CH{sub 4} in comet Hill suggests that the sublimation of these hypervolatiles sustained the outburst of the comet. Some fraction of water in the inner coma might exist as icy grains that were likely ejected from nucleus by the sublimation of hypervolatiles. Mixing ratios of volatiles in comet Hill are indicative of the interstellar heritage without significant alteration in the solar nebula.

Protein kinase A stimulates Kv7.1 surface expression by regulating Nedd4-2-dependent endocytic trafficking

DEFF Research Database (Denmark)

Andersen, Martin Nybo; Hefting, Louise Leth; Steffensen, Annette Buur

2015-01-01

The potassium channel Kv7.1 plays critical physiological roles in both heart and epithelial tissues. In heart, Kv7.1 and the accessory subunit KCNE1 forms the IKs current, which is enhanced by PKA mediated phosphorylation. The observed current increase requires both phosphorylation of Kv7.......1 and the presence of KCNE1. However, PKA also stimulates Kv7.1 currents in epithelial tissues, such as colon, where the channel does not co-assemble with KCNE1. Here, we demonstrate that PKA activity significantly impacts the subcellular localization of Kv7.1 in Madin Darby Canine Kidney cells. While PKA inhibition...... reduced the fraction of channels at the cell surface, PKA activation increased it. We show that PKA inhibition lead to intracellular accumulation of Kv7.1 in late endosomes/lysosomes. By mass spectroscopy we identified eight phosphorylated residues on Kv7.1, however, none appeared to play a role...

Transport of regional pollutions to UTLS during Asian Summer Monsoon - A CTM study

Science.gov (United States)

Li, Qian; Bian, Jianchun; Lu, Daren

2013-04-01

We use a 3-D global Chemical Transport Model (CTM) GEOS-Chem to simulate the observed Asian Summer Monsoon transport of biomass burning tracers HCN and CO from local emissions to UTLS. By analyzing the satellite observations, we focus on the distribution and spatial-temporal variation of HCN and CO concentration in UTLS. The model simulations capture well the main features of distribution of HCN and CO compared with satellite observations. Recent studies (Li et al., 2009; Randel et al., 2010) indicated that regional emissions may play an important role controlling the distribution and variation of HCN in tropical UTLS during Asian Summer Monsoon seasons, mainly due to the local dynamical uplift of Asian Summer Monsoon. By using GEOS-Chem simulations, we will analyze the UTLS distribution and variation of HCN and CO from emissions of different regions including S.E. Asia, Boreal Asia, Indonesia and Australia, Africa, Europe, Northern America and Southern America. According to the amount and seasonal variability of emissions, the contribution of biomass burning and biofuel burning emissions of different regions to the highly concentrated HCN and CO in UTLS during Asian Summer Monsoon seasons will be discussed, individually.

THE VOLATILE COMPOSITION OF COMET C/2003 K4 (LINEAR) AT NEAR-IR WAVELENGTHS—COMPARISONS WITH RESULTS FROM THE NANÇAY RADIO TELESCOPE AND FROM THE ODIN, SPITZER, AND SOHO SPACE OBSERVATORIES

Energy Technology Data Exchange (ETDEWEB)

Paganini, L.; Mumma, M. J.; Villanueva, G. L.; DiSanti, M. A.; Bonev, B. P., E-mail: lucas.paganini@nasa.gov [Goddard Center for Astrobiology, NASA GSFC, MS 690, Greenbelt, MD 20771 (United States)

2015-07-20

We observed comet C/2003 K4 (LINEAR) using NIRSPEC at the Keck Observatory on UT 2004 November 28, when the comet was at 1.28 AU from the Sun (post-perihelion) and 1.38 AU from Earth. We detected six gaseous species (H{sub 2}O, OH*, C{sub 2}H{sub 6}, CH{sub 3}OH, CH{sub 4}, and HCN) and obtained upper limits for three others (H{sub 2}CO, C{sub 2}H{sub 2}, and NH{sub 3}). Our results indicate a water production rate of (1.72 ± 0.18) × 10{sup 29} molecules s{sup −1}, in reasonable agreement with production rates from SOHO (on the same day), Odin (one day earlier), and Nançay (about two weeks earlier). We also report abundances (relative to water) for seven trace species: CH{sub 3}OH (∼1.8%), CH{sub 4} (∼0.9%), and C{sub 2}H{sub 6} (∼0.4%) that were consistent with mean values among Oort cloud (OC) comets, while NH{sub 3} (<0.55%), HCN (∼0.07%), H{sub 2}CO (<0.07%), and C{sub 2}H{sub 2} (<0.04%) were “lower” than the mean values in other OC comets. We extracted inner-coma rotational temperatures for four species (H{sub 2}O, C{sub 2}H{sub 6}, CH{sub 3}OH, and CH{sub 4}), all of which are consistent with 70 K (within 1σ). The extracted ortho-para ratio for water was 3.0 ± 0.15, corresponding to spin temperatures larger than 39 K (at the 1σ level) and agreeing with those obtained with the Spitzer Space Telescope at the 2σ level.

A Treasure Trove of Molecules: Uncovering the Molecular Content of Planetary Nebulae

Science.gov (United States)

Schmidt, Deborah Rose; Ziurys, Lucy M.

2016-06-01

We have undertaken a systematic study of the molecular content of planetary nebulae (PNe) using the facilities of the Arizona Radio Observatory (ARO). A search for HCN and HCO+ in seventeen PNe in which CO had previously been detected has been carried out. The J=1→0 and J=3→2 transitions of both molecules were searched for using the ARO 12-M Telescope and ARO Sub-Millimeter Telescope respectively. At least one transition of either molecule was detected in thirteen sources. Assuming a kinetic temperature of 20 K, the abundances of these two molecule, relative to H2, were determined to be f(HCN) ~ 0.1 - 9.1 × 10-7 and f(HCO+) ~ 0.04 - 7.4 × 10-7. The abundances of both species were found to remain relatively constant with nebular age, in contrast to predictions of chemical models. A subset of eleven of these PNe were subsequently searched for the J=1→0 and J=3→2 transitions of CCH and HNC. HNC was detected in ten sources, resulting in HCN/HNC ratios of ~2-6, while CCH has been detected in eight. The most current results for the abundances of both molecules will be reported. The correlation of CCH and C60 will also be presented. Establishing molecular abundances in PNe is vital to our understanding of their environments as well as the nature of their ejecta, which populate the interstellar medium (ISM).

Dysfunctional Hyperpolarization-Activated Cyclic Nucleotide-gated Ion Channels in Cardiac Diseases

Directory of Open Access Journals (Sweden)

Xiaoqi Zhao

Full Text Available Abstract Hyperpolarization-activated cyclic nucleotide-gated (HCN channels are reverse voltage-dependent, and their activation depends on the hyperpolarization of the membrane and may be directly or indirectly regulated by the cyclic adenosine monophosphate (cAMP or other signal-transduction cascades. The distribution, quantity and activation states of HCN channels differ in tissues throughout the body. Evidence exhibits that HCN channels play critical roles in the generation and conduction of the electrical impulse and the physiopathological process of some cardiac diseases. They may constitute promising drug targets in the treatment of these cardiac diseases. Pharmacological treatment targeting HCN channels is of benefit to these cardiac conditions.

Compact portable QEPAS multi-gas sensor

Science.gov (United States)

Dong, Lei; Kosterev, Anatoliy A.; Thomazy, David; Tittel, Frank K.

2011-01-01

A quartz-enhanced photoacoustic spectroscopy (QEPAS) based multi-gas sensor was developed to quantify concentrations of carbon monoxide (CO), hydrogen cyanide (HCN), hydrogen chloride (HCl), and carbon dioxide (CO2) in ambient air. The sensor consists of a compact package of dimensions 25cm x 25cm x 10cm and was designed to operate at atmospheric pressure. The HCN, CO2, and HCl measurement channels are based on cw, C-band telecommunication-style packaged, fiber-coupled diode lasers, while the CO channel uses a TO can-packaged Sb diode laser as an excitation source. Moreover, the sensor incorporates rechargeable batteries and can operate on batteries for at least 8 hours. It can also operate autonomously or interact with another device (such as a computer) via a RS232 serial port. Trace gas detection limits of 7.74ppm at 4288.29cm-1 for CO, 450ppb at 6539.11 cm-1 for HCN, 1.48ppm at 5739.26 cm-1 for HCl and 97ppm at 6361.25 cm-1 for CO2 for a 1sec average time, were demonstrated.

DENSE GAS IN MOLECULAR CORES ASSOCIATED WITH PLANCK GALACTIC COLD CLUMPS

Energy Technology Data Exchange (ETDEWEB)

Yuan, Jinghua; Li, Jin Zeng; Liu, Hong-Li [National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012 (China); Wu, Yuefang; Chen, Ping; Hu, Runjie [Department of Astronomy, Peking University, 100871 Beijing (China); Liu, Tie [Korea Astronomy and Space Science Institute 776, Daedeokdae-ro, Yuseong-gu, Daejeon, 305-348 (Korea, Republic of); Zhang, Tianwei [Peking University Health Science Center, Xueyuan Road 38th, Haidian District, Beijing 100191 (China); Meng, Fanyi [Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 (Germany); Wang, Ke, E-mail: ywu@pku.edu.cn [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei München (Germany)

2016-03-20

We present the first survey of dense gas toward Planck Galactic Cold Clumps (PGCCs). Observations in the J = 1–0 transitions of HCO{sup +} and HCN toward 621 molecular cores associated with PGCCs were performed using the Purple Mountain Observatory’s 13.7 m telescope. Among them, 250 sources were detected, including 230 cores detected in HCO{sup +} and 158 in HCN. Spectra of the J = 1–0 transitions from {sup 12}CO, {sup 13}CO, and C{sup 18}O at the centers of the 250 cores were extracted from previous mapping observations to construct a multi-line data set. The significantly low detection rate of asymmetric double-peaked profiles, together with the good consistency among central velocities of CO, HCO{sup +}, and HCN spectra, suggests that the CO-selected Planck cores are more quiescent than classical star-forming regions. The small difference between line widths of C{sup 18}O and HCN indicates that the inner regions of CO-selected Planck cores are no more turbulent than the exterior. The velocity-integrated intensities and abundances of HCO{sup +} are positively correlated with those of HCN, suggesting that these two species are well coupled and chemically connected. The detected abundances of both HCO{sup +} and HCN are significantly lower than values in other low- to high-mass star-forming regions. The low abundances may be due to beam dilution. On the basis of an inspection of the parameters given in the PGCC catalog, we suggest that there may be about 1000 PGCC objects that have a sufficient reservoir of dense gas to form stars.

MAPPING THE RELEASE OF VOLATILES IN THE INNER COMAE OF COMETS C/2012 F6 (LEMMON) AND C/2012 S1 (ISON) USING THE ATACAMA LARGE MILLIMETER/SUBMILLIMETER ARRAY

Energy Technology Data Exchange (ETDEWEB)

Cordiner, M. A.; Milam, S. N.; Mumma, M. J.; Charnley, S. B.; Paganini, L.; Villanueva, G. [Goddard Center for Astrobiology, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Remijan, A. J. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States); Boissier, J. [IRAM, 300 Rue de la Piscine, F-38406 Saint Martin d' Heres (France); Bockelée-Morvan, D.; Biver, N.; Crovisier, J. [LEISA, Observatoire de Paris, CNRS, UPMC, Université Paris-Diderot, 5 Place Jules Janssen, F-92195 Meudon (France); Kuan, Y.-J.; Chuang, Y.-L. [National Taiwan Normal University, Taipei 116, Taiwan (China); Lis, D. C. [Sorbonne Universités, Université Pierre et Marie Curie, Paris 6, CNRS, Observatoire de Paris, UMR 8112, LERMA, F-75014 Paris (France); Minniti, D. [Pontifica Universidad Catolica de Chile, Santiago (Chile); Coulson, I. M., E-mail: martin.cordiner@nasa.gov [Joint Astronomy Centre, Hilo, HI 96720 (United States)

2014-09-01

Results are presented from the first cometary observations using the Atacama Large Millimeter/Submillimeter Array (ALMA), including measurements of the spatially resolved distributions of HCN, HNC, H{sub 2}CO, and dust within the comae of two comets: C/2012 F6 (Lemmon) and C/2012 S1 (ISON), observed at heliocentric distances of 1.5 AU and 0.54 AU, respectively. These observations (with angular resolution ≈0.''5), reveal an unprecedented level of detail in the distributions of these fundamental cometary molecules, and demonstrate the power of ALMA for quantitative measurements of the distributions of molecules and dust in the inner comae of typical bright comets. In both comets, HCN is found to originate from (or within a few hundred kilometers of) the nucleus, with a spatial distribution largely consistent with spherically symmetric, uniform outflow. By contrast, the HNC distributions are clumpy and asymmetrical, with peaks at cometocentric radii ∼500-1000 km, consistent with release of HNC in collimated outflow(s). Compared to HCN, the H{sub 2}CO distribution in comet Lemmon is very extended. The interferometric visibility amplitudes are consistent with coma production of H{sub 2}CO and HNC from unidentified precursor material(s) in both comets. Adopting a Haser model, the H{sub 2}CO parent scale length is found to be a few thousand kilometers in Lemmon and only a few hundred kilometers in ISON, consistent with the destruction of the precursor by photolysis or thermal degradation at a rate that scales in proportion to the solar radiation flux.

EXPERIMENTAL AND COMPUTATIONAL STUDIES OF THE FORMATION MECHANISM OF PROTONATED INTERSTELLAR DIAZINES

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhe-Chen; Cole, Callie A.; Bierbaum, Veronica M. [Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309 (United States); Snow, Theodore P., E-mail: zhwa4666@colorado.edu [Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States)

2015-01-10

Studies of interstellar chemistry have grown in number and complexity by both observations and laboratory measurements, and nitrogen-containing aromatics have been implicated as important interstellar molecules. In this paper, the gas-phase collision induced dissociation (CID) processes of protonated pyridazine (1,2-diazine), pyrimidine (1,3-diazine), and pyrazine (1,4-diazine) cations (C{sub 4}H{sub 5}N{sub 2} {sup +}) are investigated in detail both experimentally and theoretically. The major neutral loss for all three CID processes is HCN, leading to the formation of C{sub 3}H{sub 4}N{sup +} isomers; our density functional theory (DFT) calculations support and elucidate our experimental results. The formation of C{sub 3}H{sub 4}N{sup +} isomers from the reaction of abundant interstellar acrylonitrile (CH{sub 2}CHCN) and H{sup +}is also studied employing DFT calculations. Our results lead to a novel mechanism for interstellar protonated diazine formation from the consecutive reactions of CH{sub 2}CHCN+ H{sup +} + HCN. Moreover, our results motivate the continuing search for interstellar C{sub 3}H{sub 4}N{sup +} isomers as well as polycyclic aromatic N-containing hydrocarbons (PANHs)

Comparison of three cyanogen assays for total cyanogens in cassava (Manihot esculenta Crantz)

DEFF Research Database (Denmark)

Saka, J.D.K.; Mhone, A.R.K.; Brimer, Leon

1997-01-01

The sensitivity and reproducibility of three methods for determining the total cyanogenic potential (CNp) of 7 fresh and processed cassava varieties were determined and compared. The total cyanogen content of fresh cassava roots and three cassava products (kondowole, makaka, and starch) were...... analysed by the acid hydrolysis, microdiffusion with solid state detection and Cooke's enzymatic assays. The total cyanogen contents of the cassava, obtained by the three methods were not significantly different (p....3+or-0.4 and 20.4+or-1.4 mg HCN eq. kg-1 fresh weight by Cooke's, acid hydrolysis and solid state methods, respectively. However, at very low cyanogen levels, less than 5 mg HCN eq. kg-1 fresh weight, the acid hydrolysis method overestimates by 3-5 times. Otherwise, their coefficients of variations...

Alkaline cyanide degradation by Pseudomonas pseudoalcaligenes CECT5344 in a batch reactor. Influence of pH

International Nuclear Information System (INIS)

Huertas, M.J.; Saez, L.P.; Roldan, M.D.; Luque-Almagro, V.M.; Martinez-Luque, M.; Blasco, R.; Castillo, F.; Moreno-Vivian, C.; Garcia-Garcia, I.

2010-01-01

Water containing cyanide was biologically detoxified with the bacterial strain Pseudomonas pseudoalcaligenes CECT5344 in a batch reactor. Volatilization of toxic hydrogen cyanide (HCN) was avoided by using an alkaline medium for the treatment. The operational procedure was optimized to assess cyanide biodegradation at variable pH values and dissolved oxygen concentrations. Using an initial pH of 10 without subsequent adjustment allowed total cyanide to be consumed at a mean rate of approximately 2.81 mg CN - L -1 O.D. -1 h -1 ; however, these conditions posed a high risk of HCN formation. Cyanide consumption was found to be pH-dependent. Thus, no bacterial growth was observed with a controlled pH of 10; on the other hand, pH 9.5 allowed up to 2.31 mg CN - L -1 O.D. -1 h -1 to be converted. The combination of a high pH and a low dissolved oxygen saturation (10%) minimized the release of HCN. This study contributes new basic knowledge about this biological treatment, which constitutes an effective alternative to available physico-chemical methods for the purification of wastewater containing cyanide or cyano-metal complexes.

Depression of molecular emission in the line of sight of Sgr A West

International Nuclear Information System (INIS)

Fukui, Y.; Ogawa, H.; Deguchi, S.; Suzuki, H.

1982-01-01

The galatic center region has been mapped in the 4-mm emission lines of HCCCN (J = 8-7) and H 2 CO (JK-K+ = 1 01 -0 00 ) with a 1.5 arc min beam. The molecular lines are found to show depression in intensity in the line of sight of Sgr A West. Comparison with other molecular data indicates that NH 3 also shows a significant depression while HCN and HCO + show little sign of similar depression. Based on some density estimates we suggest that the depression means abnormally reduced abundance in HCCCN, NH 3 , and H 2 CO in the line of sight of Sgr A West. The difference in the degree of depression could be interpreted in terms of a time-dependent ion-molecule reaction scheme because HCO + and HCN are formed much more rapidly than the other molecules in the scheme

Investigation of HNCO isomer formation in ice mantles by UV and thermal processing: An experimental approach

Energy Technology Data Exchange (ETDEWEB)

Jiménez-Escobar, A.; Giuliano, B. M.; Caro, G. M. Muñoz; Cernicharo, J. [Centro de Astrobiología, INTA-CSIC, Carretera de Ajalvir, km 4, Torrejón de Ardoz, E-28850 Madrid (Spain); Marcelino, N., E-mail: bgiuliano@cab.inta-csic.es [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)

2014-06-10

Current gas-phase models do not account for the abundances of HNCO isomers detected in various environments, suggesting their formation in icy grain mantles. We attempted to study a formation channel of HNCO and its possible isomers by vacuum-UV photoprocessing of interstellar ice analogs containing H{sub 2}O, NH{sub 3}, CO, HCN, CH{sub 3}OH, CH{sub 4}, and N{sub 2} followed by warm-up under astrophysically relevant conditions. Only the H{sub 2}O:NH{sub 3}:CO and H{sub 2}O:HCN ice mixtures led to the production of HNCO species. The possible isomerization of HNCO to its higher energy tautomers following irradiation or due to ice warm-up has been scrutinized. The photochemistry and thermal chemistry of H{sub 2}O:NH{sub 3}:CO and H{sub 2}O:HCN ices were simulated using the Interstellar Astrochemistry Chamber, a state-of-the-art ultra-high-vacuum setup. The ice was monitored in situ by Fourier transform mid-infrared spectroscopy in transmittance. A quadrupole mass spectrometer detected the desorption of the molecules in the gas phase. UV photoprocessing of H{sub 2}O:NH{sub 3}:CO and H{sub 2}O:HCN ices lead to the formation of OCN{sup –} as a main product in the solid state and a minor amount of HNCO. The second isomer HOCN has been tentatively identified. Despite its low efficiency, the formation of HNCO and the HOCN isomers by UV photoprocessing of realistic simulated ice mantles might explain the observed abundances of these species in photodissociation regions, hot cores, and dark clouds.

DENSE GAS FRACTION AND STAR FORMATION EFFICIENCY VARIATIONS IN THE ANTENNAE GALAXIES

Energy Technology Data Exchange (ETDEWEB)

Bigiel, F. [Institut für theoretische Astrophysik, Zentrum für Astronomie der Universität Heidelberg, Albert-Ueberle Strasse 2, D-69120 Heidelberg (Germany); Leroy, A. K. [Department of Astronomy, The Ohio State University, 140 W 18th Street, Columbus, OH 43210 (United States); Blitz, L. [Department of Astronomy, Radio Astronomy Laboratory, University of California, Berkeley, CA 94720 (United States); Bolatto, A. D. [Department of Astronomy and Laboratory for Millimeter-Wave Astronomy, University of Maryland, College Park, MD 20742 (United States); Da Cunha, E. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Rosolowsky, E. [Department of Physics, University of Alberta, Edmonton, AB (Canada); Sandstrom, K. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Usero, A., E-mail: bigiel@uni-heidelberg.de [Observatorio Astronomico Nacional, Alfonso XII 3, E-28014, Madrid (Spain)

2015-12-20

We use the Combined Array for Research in Millimeter-wave Astronomy (CARMA) millimeter interferometer to map the Antennae Galaxies (NGC 4038/39), tracing the bulk of the molecular gas via the {sup 12}CO(1–0) line and denser molecular gas via the high density transitions HCN(1–0), HCO{sup +}(1–0), CS(2–1), and HNC(1–0). We detect bright emission from all tracers in both the two nuclei and three locales in the overlap region between the two nuclei. These three overlap region peaks correspond to previously identified “supergiant molecular clouds.” We combine the CARMA data with Herschel infrared (IR) data to compare observational indicators of the star formation efficiency (star formation rate/H{sub 2} ∝ IR/CO), dense gas fraction (HCN/CO), and dense gas star formation efficiency (IR/HCN). Regions within the Antennae show ratios consistent with those seen for entire galaxies, but these ratios vary by up to a factor of six within the galaxy. The five detected regions vary strongly in both their integrated intensities and these ratios. The northern nucleus is the brightest region in millimeter-wave line emission, while the overlap region is the brightest part of the system in the IR. We combine the CARMA and Herschel data with ALMA CO data to report line ratio patterns for each bright point. CO shows a declining spectral line energy distribution, consistent with previous studies. HCO{sup +} (1–0) emission is stronger than HCN (1–0) emission, perhaps indicating either more gas at moderate densities or higher optical depth than is commonly seen in more advanced mergers.

A Reduced Switch Voltage Stress Class E Power Amplifier Using Harmonic Control Network

OpenAIRE

Ali Reza Zirak; Sobhan Roshani

2016-01-01

In this paper, a harmonic control network (HCN) is presented to reduce the voltage stress (maximum MOSFET voltage) of the class E power amplifier (PA). Effects of the HCN on the amplifier specifications are investigated. The results show that the proposed HCN affects several specifications of the amplifier, such as drain voltage, switch current, output power capability (Cp factor), and drain impedance. The output power capability of the presented amplifier is also improved, compared with the ...

KCNE regulation of K+ channel trafficking – a Sisyphean task?

Directory of Open Access Journals (Sweden)

Vikram Anmol Kanda

2012-06-01

Full Text Available Voltage-gated potassium (Kv channels shape the action potentials of excitable cells and regulate membrane potential and ion homeostasis in excitable and nonexcitable cells. With forty known members in the human genome and a variety of homomeric and heteromeric pore-forming alpha subunit interactions, post-translational modifications, cellular locations and expression patterns, the functional repertoire of the Kv alpha subunit family is monumental. This versatility is amplified by a host of interacting proteins, including the single membrane-spanning KCNE ancillary subunits. Here, examining both the secretory and the endocytic pathways, we review recent findings illustrating the surprising virtuosity of the KCNE proteins in orchestrating not just the function, but also the composition, diaspora and retrieval of channels formed by their Kv alpha subunit partners.

Nitrogen conversion during rapid pyrolysis of coal and petroleum coke in a high-frequency furnace

International Nuclear Information System (INIS)

Yuan, Shuai; Zhou, Zhi-jie; Li, Jun; Wang, Fu-chen

2012-01-01

Highlights: ► Use a high-frequency furnace to study N-conversion during rapid pyrolysis of coal. ► Scarcely reported N-conversion during rapid pyrolysis of petroleum coke was studied. ► Both of NH 3 and HCN can be formed directly from coal during rapid pyrolysis. ► NH 3 –N yields are higher than HCN–N yields in most conditions. ► NH 3 –N yields of petroleum coke increase with temperature and no HCN detected. -- Abstract: Rapid pyrolysis of three typical Chinese coals, lignite from Inner Mongolia, bituminous from Shenfu coalfield, and anthracite from Guizhou, as well as a petroleum coke were carried out in a drop-style high-frequency furnace. The reactor was induction coil heated and had a very small high-temperature zone, which could restrain secondary conversions of nitrogen products. The effects of temperature and coal rank on conversions of fuel-N to primary nitrogen products (char-N, HCN–N, NH 3 –N and (tar + N 2 )–N) have been investigated. The results showed that, the increasing temperature reduced the yields of char-N and promoted the conversion of fuel-N to N 2 . Char-N yields increased, while volatile-N yields decreased as the coal rank increased. In most of the conditions, NH 3 –N yields were higher than HCN–N yields during rapid pyrolysis of coal. In the case of petroleum coke, NH 3 –N yields increased gradually with the increasing temperature, but no HCN was detected. We argue that NH 3 –N can be formed directly through the primary pyrolysis without secondary reactions. Although volatile-N yields of lignite were higher than those of bituminous, yields of (HCN + NH 3 )–N in volatile-N of lignite were lower than those of bituminous. While the (HCN + NH 3 )–N yields of anthracite were the lowest of the three coals. Both of the (HCN + NH 3 )–N yields and (HCN + NH 3 )–N proportions in volatile-N of petroleum coke were lower than the three coals.

Product channels in the 193-nm photodissociation of HCNO (fulminic acid)

Energy Technology Data Exchange (ETDEWEB)

Feng, Wenhui; Hershberger, John F., E-mail: john.hershberger@ndsu.edu

2016-06-15

IR diode laser spectroscopy was used to detect the products of HCNO (fulminic acid) photolysis at 193 nm. Six product channels are energetically possible at this photolysis wavelength: O + HCN, H + NCO/CNO, CN + OH, CO + NH, NO + CH and HNCO. In some experiments, isotopically labeled {sup 15}N{sup 18}O, C{sub 2}D{sub 6} or C{sub 6}H{sub 12} reagents were included into the photolysis mixture in order to suppress and/or redirect possible secondary reactions. HCN, OC{sup 18}O, {sup 15}N{sup 15}NO, CO, DCN and HNCO molecules were detected upon laser photolysis of HCNO/reagents/buffer gas mixtures. Analysis of the yields of product molecules leads to the following photolysis quantum yields: ϕ{sub 1a} (O + HCN) = 0.38 ± 0.04, ϕ{sub 1b} (H + (NCO)) = 0.07 ± 0.02, ϕ{sub 1c} (CN + OH) = 0.24 ± 0.03, ϕ{sub 1d} (CO + NH(a{sup 1}Δ)) < 0.22 ± 0.1, ϕ{sub 1e} (HNCO) = 0.02 ± 0.01 and ϕ{sub 1f} (CH + NO) = 0.21 ± 0.1, respectively.

Assessment of carboxyhemoglobin, hydrogen cyanide and methemoglobin in fire victims: a novel approach.

Science.gov (United States)

Ferrari, Luis A; Giannuzzi, Leda

2015-11-01

To establish the cause of death, carboxyhemoglobin (COHb), total hemoglobin (tHb), methemoglobin (MetHb), and hydrogen cyanide (HCN) were quantified in the blood of fire victims. We analyzed 32 out of 33 blood samples from forensic autopsy cases in a disastrous polyurethane mattress fire, which caused the deaths of 33 inmates at a prison in Argentina in 2006. The cadaveric blood samples were collected by femoral vein puncture. These samples were analyzed using the IL80 CO-oximeter system for tHb, MetHb, and COHb levels and by microdiffusion for HCN and COHb levels. Blood alcohol (ethanol) and drugs were examined by headspace gas chromatography-flame ionization detection (HS-GC-FID) and GC-mass spectrometry (MS), respectively. Polyurethane mattress samples were analyzed according to the California 117 protocol. The saturation of COHb ranged from 10% to 43%, tHb from 2% to 19.7%, MetHb from 0.10% to 35.7%, and HCN from 0.24 to 15mg/L. These HCN values are higher than the lethal levels reported in the literature. Other toxic components routinely measured (ethanol, methanol, aldehydes, and other volatile compounds) gave negative results in the 32 cases. Neither drugs of abuse nor psychotropic drugs were detected. The results indicate that death in the 32 fire victims was probably caused in part by HCN, generated during the extensive polyurethane decomposition stimulated by a rapid increase in temperature. We also considered the influence of oxygen depletion and the formation of other volatile compounds such as NOx in this disaster, as well as pathological evidence demonstrating that heat was not the cause of death in all victims. Furthermore, statistical analysis showed that the percentage values of COHb and MetHb in the blood were not independent variables, with χ(2)=11.12 (theoretical χ(2)=4.09, degrees of freedom=12, and α=0.05). However, no correlation was found between HCN and MetHb in the blood of the victims. This is the first report to assess the

On Estimation of Contamination from Hydrogen Cyanide in Carbon Monoxide Line-intensity Mapping

Energy Technology Data Exchange (ETDEWEB)

Chung, Dongwoo T.; Li, Tony Y.; Viero, Marco P.; Church, Sarah E.; Wechsler, Risa H., E-mail: dongwooc@stanford.edu [Kavli Institute for Particle Astrophysics and Cosmology, Physics Department, Stanford University, Stanford, CA 94305 (United States)

2017-09-01

Line-intensity mapping surveys probe large-scale structure through spatial variations in molecular line emission from a population of unresolved cosmological sources. Future such surveys of carbon monoxide line emission, specifically the CO(1-0) line, face potential contamination from a disjointed population of sources emitting in a hydrogen cyanide emission line, HCN(1-0). This paper explores the potential range of the strength of HCN emission and its effect on the CO auto power spectrum, using simulations with an empirical model of the CO/HCN–halo connection. We find that effects on the observed CO power spectrum depend on modeling assumptions but are very small for our fiducial model, which is based on current understanding of the galaxy–halo connection. Given the fiducial model, we expect the bias in overall CO detection significance due to HCN to be less than 1%.

Improvement of cassava for high dry matter, starch and low cyanogenic glucoside content by mutation induction

Energy Technology Data Exchange (ETDEWEB)

Nwachukwu, E C; Mbanaso, E N.A.; Ene, L S.O. [Plant Breeding Div., National Root Crops Research Inst., Umudike, Umuahia (Nigeria)

1997-07-01

Cassava (Manihot esculenta Crantz) is an important food in Nigeria. One drawback in its use as a staple food is the presence of cyanogenic glucosides which on hydrolysis produce the very toxic hydrogen cyanide (HCN). To reduce the cyanogenic levels by mutation induction, three locally adopted and high yielding varieties of cassava, TMS 30572, NR 8817 and NR 84111 were irradiated with 20, 25 and 30 Gy gamma rays. There were a wide variation in HCN, dry matter and starch content of irradiated cassava plants, screened in the MV{sub 2} propagation. Fourteen cassavavariant lines were selected for low HCN content, and 22 lines for high dry matter content. These will be further tested for yield in replicated field trials. (author). 7 refs, 3 tabs.

Improvement of cassava for high dry matter, starch and low cyanogenic glucoside content by mutation induction

International Nuclear Information System (INIS)

Nwachukwu, E.C.; Mbanaso, E.N.A.; Ene, L.S.O.

1997-01-01

Cassava (Manihot esculenta Crantz) is an important food in Nigeria. One drawback in its use as a staple food is the presence of cyanogenic glucosides which on hydrolysis produce the very toxic hydrogen cyanide (HCN). To reduce the cyanogenic levels by mutation induction, three locally adopted and high yielding varieties of cassava, TMS 30572, NR 8817 and NR 84111 were irradiated with 20, 25 and 30 Gy gamma rays. There were a wide variation in HCN, dry matter and starch content of irradiated cassava plants, screened in the MV 2 propagation. Fourteen cassavavariant lines were selected for low HCN content, and 22 lines for high dry matter content. These will be further tested for yield in replicated field trials. (author). 7 refs, 3 tabs

The Unexpectedly Bright Comet C-2012 F6 (Lemmon) Unveiled at Near-Infrared Wavelengths

Science.gov (United States)

Paganini, Lucas; Disanti, Michael A.; Mumma, Michael J.; Villanueva, Geronimo L.; Bonev, Boncho P.; Keane, Jacqueline V.; Gibb, Erika L.; Boehnhardt, Hermann; Meech, Karen J.

2013-01-01

We acquired near-infrared spectra of the Oort cloud comet C/2012 F6 (Lemmon) at three different heliocentric distances (R h) during the comet's 2013 perihelion passage, providing a comprehensive measure of the outgassing behavior of parent volatiles and cosmogonic indicators. Our observations were performed pre-perihelion at R h = 1.2 AU with CRIRES (on 2013 February 2 and 4), and post-perihelion at R h = 0.75 AU with CSHELL (on March 31 and April 1) and R h = 1.74 AU with NIRSPEC (on June 20). We detected 10 volatile species (H2O, OH* prompt emission, C2H6, CH3OH, H2CO, HCN, CO, CH4, NH3, and NH2), and obtained upper limits for two others (C2H2 and HDO). One-dimensional spatial profiles displayed different distributions for some volatiles, confirming either the existence of polar and apolar ices, or of chemically distinct active vents in the nucleus. The ortho-para ratio for water was 3.31 +/- 0.33 (weighted mean of CRIRES and NIRSPEC results), implying a spin temperature >37 K at the 95% confidence limit. Our (3s) upper limit for HDO corresponds to D/H comet C/2012 F6 as rather depleted in C2H6 and CH3OH, while HCN, CH4, and CO displayed abundances close to their median values found among comets. H2CO was the only volatile showing a relative enhancement. The relative paucity of C2H6 and CH3OH (with respect to H2O) suggests formation within warm regions of the nebula. However, the normal abundance of HCN and hypervolatiles CH4 and CO, and the enhancement of H2CO, may indicate a possible heterogeneous nucleus of comet C/2012 F6 (Lemmon), possibly as a result of radial mixing within the protoplanetary disk

Alkaline cyanide degradation by Pseudomonas pseudoalcaligenes CECT5344 in a batch reactor. Influence of pH

Energy Technology Data Exchange (ETDEWEB)

Huertas, M.J., E-mail: mjhuertas@us.es [Instituto de Bioquimica Vegetal y Fotosintesis, CSIC-Universidad de Sevilla Avda Americo Vespucio, 49, 41092 Sevilla (Spain); Saez, L.P.; Roldan, M.D.; Luque-Almagro, V.M.; Martinez-Luque, M. [Departamento de Bioquimica y Biologia Molecular, Edificio Severo Ochoa, 1a Planta, Campus de Rabanales, Universidad de Cordoba, 14071 Cordoba (Spain); Blasco, R. [Departamento de Bioquimica y Biologia Molecular y Genetica, Facultad de Veterinaria, Universidad de Extremadura, 11071 Caceres (Spain); Castillo, F.; Moreno-Vivian, C. [Departamento de Bioquimica y Biologia Molecular, Edificio Severo Ochoa, 1a Planta, Campus de Rabanales, Universidad de Cordoba, 14071 Cordoba (Spain); Garcia-Garcia, I. [Departamento de Ingenieria Quimica, Edificio Marie Curie, Campus de Rabanales, Universidad de Cordoba, 14071 Cordoba (Spain)

2010-07-15

Water containing cyanide was biologically detoxified with the bacterial strain Pseudomonas pseudoalcaligenes CECT5344 in a batch reactor. Volatilization of toxic hydrogen cyanide (HCN) was avoided by using an alkaline medium for the treatment. The operational procedure was optimized to assess cyanide biodegradation at variable pH values and dissolved oxygen concentrations. Using an initial pH of 10 without subsequent adjustment allowed total cyanide to be consumed at a mean rate of approximately 2.81 mg CN{sup -} L{sup -1} O.D.{sup -1} h{sup -1}; however, these conditions posed a high risk of HCN formation. Cyanide consumption was found to be pH-dependent. Thus, no bacterial growth was observed with a controlled pH of 10; on the other hand, pH 9.5 allowed up to 2.31 mg CN{sup -} L{sup -1} O.D.{sup -1} h{sup -1} to be converted. The combination of a high pH and a low dissolved oxygen saturation (10%) minimized the release of HCN. This study contributes new basic knowledge about this biological treatment, which constitutes an effective alternative to available physico-chemical methods for the purification of wastewater containing cyanide or cyano-metal complexes.

Quantum dynamics study on the binding of a positron to vibrationally excited states of hydrogen cyanide molecule

Science.gov (United States)

Takayanagi, Toshiyuki; Suzuki, Kento; Yoshida, Takahiko; Kita, Yukiumi; Tachikawa, Masanori

2017-05-01

We present computational results of vibrationally enhanced positron annihilation in the e+ + HCN/DCN collisions within a local complex potential model. Vibrationally elastic and inelastic cross sections and effective annihilation rates were calculated by solving a time-dependent complex-potential Schrödinger equation under the ab initio potential energy surface for the positron attached HCN molecule, [HCN; e+], with multi-component configuration interaction level (Kita and Tachikawa, 2014). We discuss the effect of vibrational excitation on the positron affinities from the obtained vibrational resonance features.

DENSE GAS TRACERS AND STAR FORMATION LAWS IN ACTIVE GALAXIES: APEX SURVEY OF HCN J = 4 → 3, HCO{sup +} J = 4 → 3, AND CS J = 7 → 6

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zhi-Yu; Gao, Yu; Zhao, Yinghe [Purple Mountain Observatory/Key Lab for Radio Astronomy, 2 West Beijing Road, Nanjing 210008 (China); Henkel, Christian; Menten, Karl M.; Güsten, Rolf [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Wang, Junzhi, E-mail: zyzhang@pmo.ac.cn [Shanghai Astronomical Observatory, 80 Nandan Road, Shanghai 200030 (China)

2014-04-01

We report HCN J = 4 → 3, HCO{sup +} J = 4 → 3, and CS J = 7 → 6 observations in 20 nearby star-forming galaxies with the Atacama Pathfinder EXperiment 12 m telescope. Combined with four HCN, three HCO{sup +}, and four CS detections from the literature, we probe the empirical link between the luminosity of molecular gas (L{sub gas}{sup ′}) and that of infrared emission (L {sub IR}), up to the highest gas densities (∼10{sup 6} cm{sup –3}) that have been probed so far. For nearby galaxies with large radii, we measure the IR luminosity within the submillimeter beam size (14''-18'') to match the molecular emission. We find linear slopes for L{sub CS} {sub J=7--6}{sup ′}-L {sub IR} and L{sub HCN} {sub J=4--3}{sup ′}-L {sub IR}, and a slightly super-linear slope for L{sub HCO{sup +}} {sub J=4--3}{sup ′}-L {sub IR}. The correlation of L{sub CS} {sub J=7--6}{sup ′}-L {sub IR} even extends over eight orders of luminosity magnitude down to Galactic dense cores, with a fit of log(L {sub IR}) =1.00(± 0.01) ×log(L{sub CS} {sub J=7--6}{sup ′}) + 4.03(± 0.04). Such linear correlations appear to hold for all densities >10{sup 4} cm{sup –3}, and indicate that star formation rate is not related to the free-fall timescale for dense molecular gas.

The importance of fuel properties in the formation of nitrogen oxides and in combustion

International Nuclear Information System (INIS)

Huotari, J.; Aho, M.; Haemaelaeinen, J.; Huotari, J.; Saastamoinen, J.; Rantanen, J.

1995-01-01

The goal of this work is to find new information about the effects of pressure, temperature and fuel properties (Fuel-O/Fuel-N) on the formation of nitrogen oxides through the most important intermediates (NH 3 and HCN). In addition, a single particle model for the simultaneous pyrolysis and char combustion will be improved to be used for calculating combustion under pressure. Experimental work is done with an electrically heated pressurized entrained flow reactor (PEFR) which is equipped with modern analytics (as FT-IR for the analysis of N 2 O, NO and NO 2 and FT-IR pyrometry for the measurement of particle temperatures). The experimental work is carried out in several stages: (a) Study of the formation of HCN and NH 3 during pressurized pyrolysis (b) Oxidation of HCN and NH 3 to nitrogen oxides in pressurized combustion (c) Reduction of NO by NH 3 under pressure (thermax denox) Task a is performed with fuels of various O/N ratio. Task b is performed with pure HCN and NH 3 and with more complicated gas mixtures including HCN and NH 3 . A large part of these results are utilized in kinetic modelling in Aabo Akademi University, Finland in project LIEKKI 2-201. Two kinds of modelling work is performed in VTT in this project (a) Simultaneous modelling of the composition of solid and gaseous phases in the pyrolysis and combustion of a small fuel particle (multiphase modelling) (b) Modelling of pyrolysis and combustion of a single fuel particle under pressurized conditions (single particle modelling). The results can be used in planning of pressurized combustors and in minimizing the emissions of nitrogen oxides. (author)

Novel Kv7.1-phosphatidylinositol 4,5-bisphosphate interaction sites uncovered by charge neutralization scanning

DEFF Research Database (Denmark)

Eckey, Karina; Wrobel, Eva; Strutz-Seebohm, Nathalie

2014-01-01

Kv7.1 to Kv7.5 α-subunits belong to the family of voltage-gated potassium channels (Kv). Assembled with the β-subunit KCNE1, Kv7.1 conducts the slowly activating potassium current IKs, which is one of the major currents underlying repolarization of the cardiac action potential. A known regulator...... of corresponding long QT syndrome mutants suggested impaired PIP2 regulation as the cause for channel dysfunction. To clarify the underlying structural mechanism of PIP2 binding, molecular dynamics simulations of Kv7.1/KCNE1 complexes containing two PIP2 molecules in each subunit at specific sites were performed...

Hydrogen Cyanide In Protoplanetary Disks

Science.gov (United States)

Walker, Ashley L.; Oberg, Karin; Cleeves, L. Ilsedore

2018-01-01

The chemistry behind star and planet formation is extremely complex and important in the formation of habitable planets. Life requires molecules containing carbon, oxygen, and importantly, nitrogen. Hydrogen cyanide, or HCN, one of the main interstellar nitrogen carriers, is extremely dangerous here on Earth. However, it could be used as a vital tool for tracking the chemistry of potentially habitable planets. As we get closer to identifying other habitable planets, we must understand the beginnings of how those planets are formed in the early protoplanetary disk. This project investigates HCN chemistry in different locations in the disk, and what this might mean for forming planets at different distances from the star. HCN is a chemically diverse molecule. It is connected to the formation for other more complex molecules and is commonly used as a nitrogen tracer. Using computational chemical models we look at how the HCN abundance changes at different locations. We use realistic and physically motivated conditions for the gas in the protoplanetary disk: temperature, density, and radiation (UV flux). We analyze the reaction network, formation, and destruction of HCN molecules in the disk environment. The disk environment informs us about stability of habitable planets that are created based on HCN molecules. We reviewed and compared the difference in the molecules with a variety of locations in the disk and ultimately giving us a better understanding on how we view protoplanetary disks.

Optical Depth Estimates and Effective Critical Densities of Dense Gas Tracers in the Inner Parts of Nearby Galaxy Discs

OpenAIRE

Jimenez-Donaire, M. J.; Bigiel, F.; Leroy, A. K.; Cormier, D.; Gallagher, M.; Usero, A.; Bolatto, A.; Colombo, D.; Garcia-Burillo, S.; Hughes, A.; Kramer, C.; Krumholz, M. R.; Meier, D. S.; Murphy, E.; Pety, J.

2016-01-01

High critical density molecular lines like HCN(1-0) or HCO+(1-0) represent our best tool to study currently star-forming, dense molecular gas at extragalactic distances. The optical depth of these lines is a key ingredient to estimate the effective density required to excite emission. However, constraints on this quantity are even scarcer in the literature than measurements of the high density tracers themselves. Here, we combine new observations of HCN, HCO+ and HNC(1-0) and their optically ...

Trojan Horses or Local Allies

DEFF Research Database (Denmark)

Müllner, Jakob; Klopf, Patricia; Nell, Phillip C.

2017-01-01

We investigate a multinational corporation's (MNC) decision to appoint host-country national (HCN) managers to foreign subsidiaries based on the institutional context of and familiarity with the host country. HCN managers are commonly associated with specialized knowledge, superior responsiveness...

Effects of alkali and alkaline earth metals on nitrogen release during temperature programmed pyrolysis of coal

Energy Technology Data Exchange (ETDEWEB)

Ohtsuka, Y.; Wu, Z.; Furimsky, E. [Tohoku University, Sendai (Japan). Inst. for Chemical Reaction Science

1997-11-01

The paper reports that the formation of HCN, NH{sub 3} and N{sub 2} during fixed-bed pyrolysis at 10 K min{sup -1} has been studied using coal samples after partial demineralization followed by addition of metal hydroxides from aqueous systems. Without additives, NH{sub 3} is the predominant product at {le} 700{degree}C, showing the two peaks in the formation rate profile, whereas N{sub 2} is the only product at {ge} 800{degree}C. The presence of NaOH, KOH and Ca(OH){sub 2} promotes considerable NH{sub 3} formation between 450 and 600{degree}C, but in contrast suppresses HCN formation in this region. The Ca shows the largest effect on both the promotion and suppression. It is likely that the NH{sub 3} increased by Ca addition arises partly from HCN, but mainly from secondary reactions of tar-N. These hydroxides affect N{sub 2} formation in quite different manners: the Na decreases the rate between 700 and 950{degree}C, and the K changes it less significantly than the Na, but the Ca remarkably increases the rate in a low temperature region of 550-700{degree}C. These different features are discussed in terms of solid-phase reactions of alkali metal carbonates with char-N and secondary decomposition reactions of tar-N on CaO particles. As a result, total conversion of coal-N to HCN, NH{sub 3} and N{sub 2} up to 1000{degree}C increases in the sequence of Na {lt} none {lt} K {lt} Ca. 40 refs., 10 figs., 2 tabs.

Corona discharge experiments in admixtures of N2 and CH4: a laboratory simulation of Titan's atmosphere

International Nuclear Information System (INIS)

Horvath, G; Skalny, J D; Klas, M; Zahoran, M; Mason, N J; Vladoiu, R; Manole, M

2009-01-01

A positive corona discharge fed by a N 2 : CH 4 mixture (98 : 2) at atmospheric pressure and ambient temperature has been studied as a laboratory mimic of the chemical processes occurring in the atmosphere of Titan, Saturn's largest moon. In situ measurements of UV and IR transmission spectra within the discharge have shown that the main chemical product is C 2 H 2 , produced by dissociation of CH 4 , with small but significant traces of ethane and HCN, all species that have been detected in Titan's atmosphere. A small amount (0.2%) of CH 4 was decomposed after 12 min of treatment requiring an average energy of 2.7 kWh g -1 . After 14 min the discharge was terminated due to the formation of a solid yellow deposit on the central wire electrode. Such a deposit is similar to that observed in other discharges and is believed to be an analogue of the aerosol and dust observed in Titan's atmosphere and is composed of chemical species commonly known as 'tholins'. We have also explored the electrical properties of the discharge. The admixture of methane into nitrogen caused an increase in the onset voltage of the discharge and consequently led to a reduction in the measured discharge current.

The Volatile Composition of newly-discovered C/2017 E4 (Lovejoy) before its dissolutionas revealed by iSHELL at NASA/IRTF

Science.gov (United States)

Faggi, Sara; Villanueva, Geronimo Luis; Mumma, Michael J.; Paganini, Lucas

2017-10-01

In April 2017, we acquired comprehensive high-resolution spectra of newly-discovered comet C/2017 E4 (Lovejoy) as it approached perihelion, and before its disintegration. We detected many cometary emission lines across 4 customized instrument settings (L1-b, L3, Lp1-b and M1) in the (1 - 5) μm range, using iSHELL - the new near-IR high resolution immersion echelle spectrograph on NASA/IRTF (Mauna Kea, Hawaii).In M1, near 5μm, we detected multiple ro-vibrational lines of H2O, CO and the (X-X) system of CN; the latter data constitute a complete survey of CN at these wavelengths. We derived quantitative abundances for CN and addressed its origin by comparing with quantitative production rates for HCN. The ability to quantify both primary and product species eliminates systematic error that may be introduced when measurements are acquired with different astronomical techniques and instruments.In L1, around 3 μm, we detected fluorescence emission from HCN, C2H2, and water, prompt emission from OH, and many other features. Methane, ethane and methanol were detected both in L3 and Lp1 settings. These species are relevant to astrobiology, owing to questions regarding the origin of pre-biotic organics and water on terrestrial planets.The many water emission lines detected in L1-b (and M1) provided an opportunity to retrieve independent measures of rotational temperature for ortho- and para-H2O, thereby reducing systematic uncertainty in the derived ortho-para ratio and nuclear spin temperature. Deuterated species were also sought and results will be presented.The bright Oort cloud comet E4 Lovejoy combined with the new capabilities of iSHELL provided unique results. The individual iSHELL settings cover very wide spectral range with very high accuracy, eliminating many sources of systematic errors when retrieving molecular abundances; future comparisons amongst comets will clarify the nature and meaning of cosmogonic indicators based on composition.Acknowledgments NASA�

High-performance supercapacitors of carboxylate-modified hollow carbon nanospheres coated on flexible carbon fibre paper: Effects of oxygen-containing group contents, electrolytes and operating temperature

International Nuclear Information System (INIS)

Phattharasupakun, Nutthaphon; Wutthiprom, Juthaporn; Suktha, Phansiri; Iamprasertkun, Pawin; Chanlek, Narong; Shepherd, Celine; Hadzifejzovic, Emina; Moloney, Mark G.; Foord, John S.; Sawangphruk, Montree

2017-01-01

Although functionalized carbon-based materials have been widely used as the supercapacitor electrodes, the optimum contents of the functional groups, the charge storage mechanisms, and the effects of electrolytes and operating temperature have not yet been clearly investigated. In this work, carboxylate-modified hollow carbon nanospheres (c-HCN) with different functional group contents synthesized by an oxidation process of carbon nanospheres with nitric acid were coated on flexible carbon fibre paper and used as the supercapacitor electrodes. An as-fabricated supercapacitor of the c-HCN with a finely tuned 6.2 atomic % of oxygen of the oxygen-containing groups in an ionic liquid electrolyte exhibits a specific capacitance of 390 F g"−"1, a specific energy of 115 Wh kg"−"1, and a maximum specific power of 13548 W kg"−"1 at 70 °C. The charge storage mechanism investigated is based on the chemical adsorption of the ionic liquid electrolyte on the c-HCN electrode. This process is highly reversible leading to high capacity retention. The supercapacitor in this work may be practically used in many high energy and power applications.

C/2013 R1 (Lovejoy) at IR wavelengths and the variability of CO abundances among Oort Cloud comets

Energy Technology Data Exchange (ETDEWEB)

Paganini, L.; Mumma, M. J.; Villanueva, G. L.; Bonev, B. P.; DiSanti, M. A. [Goddard Center for Astrobiology, NASA GSFC, MS 690, Greenbelt, MD 20771 (United States); Keane, J. V.; Meech, K. J. [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Blake, G. A. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Gibb, E. L., E-mail: lucas.paganini@nasa.gov [Department of Physics and Astronomy, University of Missouri-St. Louis, St. Louis, MO 63121 (United States)

2014-08-20

We report production rates, rotational temperatures, and related parameters for gases in C/2013 R1 (Lovejoy) using the Near InfraRed SPECtrometer at the Keck Observatory, on six UT dates spanning heliocentric distances (R{sub h} ) that decreased from 1.35 AU to 1.16 AU (pre-perihelion). We quantified nine gaseous species (H{sub 2}O, OH*, CO, CH{sub 4}, HCN, C{sub 2}H{sub 6}, CH{sub 3}OH, NH{sub 3}, and NH{sub 2}) and obtained upper limits for two others (C{sub 2}H{sub 2} and H{sub 2}CO). Compared with organics-normal comets, our results reveal highly enriched CO, (at most) slightly enriched CH{sub 3}OH, C{sub 2}H{sub 6}, and HCN, and CH{sub 4} consistent with {sup n}ormal{sup ,} yet depleted, NH{sub 3}, C{sub 2}H{sub 2}, and H{sub 2}CO. Rotational temperatures increased from ∼50 K to ∼70 K with decreasing R{sub h} , following a power law in R{sub h} of –2.0 ± 0.2, while the water production rate increased from 1.0 to 3.9 × 10{sup 28} molecules s{sup –1}, following a power law in R{sub h} of –4.7 ± 0.9. The ortho-para ratio for H{sub 2}O was 3.01 ± 0.49, corresponding to spin temperatures (T {sub spin}) ≥ 29 K (at the 1σ level). The observed spatial profiles for these emissions showed complex structures, possibly tied to nucleus rotation, although the cadence of our observations limits any definitive conclusions. The retrieved CO abundance in Lovejoy is more than twice the median value for comets in our IR survey, suggesting this comet is enriched in CO. We discuss the enriched value for CO in comet C/2013 R1 in terms of the variability of CO among Oort Cloud comets.

Trojan Horses or Local Allies

DEFF Research Database (Denmark)

Müllner, Jakob; Klopf, Patricia; Nell, Phillip Christopher

We investigate an MNC’s decision to appoint host-country national (HCN) managers to foreign subsidiaries based on the institutional context of and familiarity with the host country. HCN managers are commonly associated with specialized knowledge, superior responsiveness, and higher legitimacy. On...

Electronic structure and thermal decomposition of 5-aminotetrazole studied by UV photoelectron spectroscopy and theoretical calculations

Energy Technology Data Exchange (ETDEWEB)

Pinto, Rui M., E-mail: ruipinto@fct.unl.pt [CFA, Centro de Fisica Atomica, Departamento de Fisica, Faculdade de Ciencias e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Dias, Antonio A.; Costa, Maria L. [CFA, Centro de Fisica Atomica, Departamento de Fisica, Faculdade de Ciencias e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)

2011-03-18

Graphical abstract: Gas-phase UV photoelectron spectrum of the thermal decomposition of 5-aminotetrazole (5ATZ), obtained at 245 {sup o}C, and mechanism underlying the thermal dissociation of 2H-5ATZ. Research highlights: {yields} Electronic structure of 5ATZ studied by photoelectron spectroscopy. {yields} Gas-phase 5-ATZ exists mainly as the 2H-tautomer. {yields} Thermal decomposition of 5ATZ gives N{sub 2}, NH{sub 2}CN, HN{sub 3} and HCN, at 245 {sup o}C. {yields} HCN can be originated from a carbene intermediate. - Abstract: The electronic properties and thermal decomposition of 5-aminotetrazole (5ATZ) are investigated using UV photoelectron spectroscopy (UVPES) and theoretical calculations. Simulated spectra of both 1H- and 2H-5ATZ, based on electron propagator methods, are produced in order to study the relative gas-phase tautomer population. The thermal decomposition results are rationalized in terms of intrinsic reaction coordinate (IRC) calculations. 5ATZ yields a HOMO ionization energy of 9.44 {+-} 0.04 eV and the gas-phase 5ATZ assumes mainly the 2H-form. The thermal decomposition of 5ATZ leads to the formation of N{sub 2}, HN{sub 3} and NH{sub 2}CN as the primary products, and HCN from the decomposition of a intermediate CH{sub 3}N{sub 3} compound. The reaction barriers for the formation of HN{sub 3} and N{sub 2} from 2H-5ATZ are predicted to be {approx}228 and {approx}150 kJ/mol, at the G2(MP2) level, respectively. The formation of HCN and HNNH from the thermal decomposition of a CH{sub 3}N{sub 3} carbene intermediate is also investigated.

THE ABUNDANCES OF POLYACETYLENES TOWARD CRL618

International Nuclear Information System (INIS)

Fonfria, J. P.; Cernicharo, J.; Richter, M. J.; Lacy, J. H.

2011-01-01

We present a mid-infrared high spectral resolution spectrum of CRL618 in the frequency ranges 778-784 and 1227-1249 cm -1 (8.01-8.15 and 12.75-12.85 μm) taken with the Texas Echelon-cross-Echelle Spectrograph (TEXES) and the Infrared Telescope Facility (IRTF). We have identified more than 170 rovibrational lines arising from C 2 H 2 , HCN, C 4 H 2 , and C 6 H 2 . We have found no unmistakable trace of C 8 H 2 . The line profiles display a complex structure suggesting the presence of polyacetylenes in several components of the circumstellar envelope (CSE). We derive total column densities of 2.5 x 10 17 , 3.1 x 10 17 , 2.1 x 10 17 , 9.3 x 10 16 cm -2 , and ∼ 16 cm -2 for HCN, C 2 H 2 , C 4 H 2 , C 6 H 2 , and C 8 H 2 , respectively. The observations indicate that both the rotational and vibrational temperatures in the innermost CSE depend on the molecule, varying from 100 to 350 K for the rotational temperatures and 100 to 500 K for the vibrational temperatures. Our results support a chemistry in the innermost CSE based on radical-neutral reactions triggered by the intense UV radiation field.

Organic chemistry of NH3 and HCN induced by an atmospheric abnormal glow discharge in N2-CH4 mixtures

OpenAIRE

2010-01-01

Abstract The formation of the chemical products produced in an atmospheric glow discharge fed by a N2-CH4 gas mixture has been studied using Fourier Transform InfraRed (FTIR) and Optical Emission Spectrometry (OES). The measurements were carried out in a flowing regime at ambient temperature and pressure with CH4 concentrations ranging from 0.5% to 2%. In the recorded emission spectra the lines of the second positive system CN system and the first negative s...

Bacteria of the Burkholderia cepacia complex are cyanogenic under biofilm and colonial growth conditions

Directory of Open Access Journals (Sweden)

Hoshino Saiko

2008-06-01

Full Text Available Abstract Background The Burkholderia cepacia complex (Bcc is a collection of nine genotypically distinct but phenotypically similar species. They show wide ecological diversity and include species that are used for promoting plant growth and bio-control as well species that are opportunistic pathogens of vulnerable patients. Over recent years the Bcc have emerged as problematic pathogens of the CF lung. Pseudomonas aeruginosa is another important CF pathogen. It is able to synthesise hydrogen cyanide (HCN, a potent inhibitor of cellular respiration. We have recently shown that HCN production by P. aeruginosa may have a role in CF pathogenesis. This paper describes an investigation of the ability of bacteria of the Bcc to make HCN. Results The genome of Burkholderia cenocepacia has 3 putative HCN synthase encoding (hcnABC gene clusters. B. cenocepacia and all 9 species of the Bcc complex tested were able to make cyanide at comparable levels to P. aeruginosa, but only when grown surface attached as colonies or during biofilm growth on glass beads. In contrast to P. aeruginosa and other cyanogenic bacteria, cyanide was not detected during planktonic growth of Bcc strains. Conclusion All species in the Bcc are cyanogenic when grown as surface attached colonies or as biofilms.

The influence of instrumental line shape degradation on NDACC gas retrievals: total column and profile

Directory of Open Access Journals (Sweden)

Y. Sun

2018-05-01

Full Text Available We simulated instrumental line shape (ILS degradations with respect to typical types of misalignment, and compared their influence on each NDACC (Network for Detection of Atmospheric Composition Change gas. The sensitivities of the total column, the root mean square (rms of the fitting residual, the total random uncertainty, the total systematic uncertainty, the total uncertainty, degrees of freedom for signal (DOFs, and the profile with respect to different levels of ILS degradation for all current standard NDACC gases, i.e. O3, HNO3, HCl, HF, ClONO2, CH4, CO, N2O, C2H6, and HCN, were investigated. The influence of an imperfect ILS on NDACC gases' retrieval was assessed, and the consistency under different meteorological conditions and solar zenith angles (SZAs were examined. The study concluded that the influence of ILS degradation can be approximated by the linear sum of individual modulation efficiency (ME amplitude influence and phase error (PE influence. The PE influence is of secondary importance compared with the ME amplitude. Generally, the stratospheric gases are more sensitive to ILS degradation than the tropospheric gases, and the positive ME influence is larger than the negative ME. For a typical ILS degradation (10 %, the total columns of stratospheric gases O3, HNO3, HCl, HF, and ClONO2 changed by 1.9, 0.7, 4, 3, and 23 %, respectively, while the columns of tropospheric gases CH4, CO, N2O, C2H6, and HCN changed by 0.04, 2.1, 0.2, 1.1, and 0.75 %, respectively. In order to suppress the fractional difference in the total column for ClONO2 and other NDACC gases within 10 and 1 %, respectively, the maximum positive ME degradations for O3, HNO3, HCl, HF, ClONO2, CO, C2H6, and HCN should be less than 6, 15, 5, 5, 5, 5, 9, and 13 %, respectively; the maximum negative ME degradations for O3, HCl, and HF should be less than 6, 12, and 12 %, respectively; the influence of ILS degradation on CH4 and N2O can be regarded as being

Het cyanophore karakter van witte klaver (Trifolium repens L.)

NARCIS (Netherlands)

Waal, de D.

1942-01-01

The positive correlation found in New Zealand between quality of white clover and its hydrocyanic acid content, could not be confirmed for Dutch white clover in the Netherlands. HCN occurred bound to an incompletely identified glucoside. As Weevers and Treub et al. found the glucoside and HCN

Hydrocyanic acid content and growth rate of sorghum x sudangrass hybrid during fall

Directory of Open Access Journals (Sweden)

Flávia Fernanda Simili

2013-08-01

Full Text Available In central Brazil after soybean or other annual agricultural species is harvested, sorghum hybrids are planted in the fall in order to establish pastures for grazing animals. This study conducted for two consecutive years aimed at quantifying the contents of hydrocyanic acid in the leaves and determining plant height, forage dry matter yield and the leaf/stem ratio for sorghum hybrid 1P400 at different ages. Statistical analysis was performed by regression analysis based on plant age. Leaf HCN content decreased with plant growth, ranging from 205.0 and 230.3 mg HCN/100 g leaf DM at two weeks old to 5.9 and 6.1 mg HCN/100 g leaf DM at five weeks old in the first and second year, respectively. The average heights measured varied from 60 and 56 cm, in the 4th week, to 117 and 151 cm, in the 8th week, during the first and second experimental year, respectively. Forage mass increased linearly with age and displayed average of 1.411 and 1.637 kg DM/ha in the first year and, 2.905 and 3.640 kg DM/ha in the second year, during the 7th and 8th week, respectively. Leaf proportion decreased while stem increased linearly with plant age. The leaf/stem ratio decreased with plant growth, elongation and increasing stem weight. The sorghum hybrid should be grazed only after five weeks or when the plant height is above 80 cm, in order to avoid the risk of cyanide poisoning.

Does KCNE5 play a role in long QT syndrome?

DEFF Research Database (Denmark)

Hofman-Bang, Jacob; Jespersen, Thomas; Grunnet, Morten

2004-01-01

BACKGROUND: Long QT syndrome [LQTS] is a congenital cardiac disease characterised by prolonged QTC-time, syncopes and sudden cardiac death. LQTS is caused by mutations in genes coding for ion channels involved in the action potential. KCNE5 codes for a novel beta-subunit of the ion channel conduc...

The essential signature of a massive starburst in a distant quasar.

Science.gov (United States)

Solomon, P; Vanden Bout, P; Carilli, C; Guelin, M

2003-12-11

Observations of carbon monoxide emission in high-redshift (zeta > 2) galaxies indicate the presence of large amounts of molecular gas. Many of these galaxies contain an active galactic nucleus powered by accretion of gas onto a supermassive black hole, and a key question is whether their extremely high infrared luminosities result from the active galactic nucleus, from bursts of massive star formation (associated with the molecular gas), or both. In the Milky Way, high-mass stars form in the dense cores of interstellar molecular clouds, where gas densities are n(H2) > 10(5) cm(-3) (refs 1, 2). Recent surveys show that virtually all galactic sites of high-mass star formation have similarly high densities. The bulk of the cloud material traced by CO observations, however, is at a much lower density. For galaxies in the local Universe, the HCN molecule is an effective tracer of high-density molecular gas. Here we report observations of HCN emission from the infrared-luminous 'Cloverleaf' quasar (at a redshift zeta = 2.5579). The HCN line luminosity indicates the presence of 10 billion solar masses of very dense gas, an essential feature of an immense starburst, which contributes, together with the active galactic nucleus it harbours, to its high infrared luminosity.

Aspects on prediction of two-phase reacting flow in a swirl-stabilized pulverized coal flame

Energy Technology Data Exchange (ETDEWEB)

Wennerberg, D. (LSTM, Erlangen (Germany))

1991-01-01

Knowledge of NO{sub x} formation routes in a pulverized coal flame is essential for understanding the problematics. Coal-bound N is the dominated source of NO{sub x} in a pf flame. The so-called 'thermal' NO{sub x} plays a minor role, since the temperature level is lower in a pf flame than in a gas - or oilfired flame. The coalbound N is mainly released along with the volatiles in the coal as HCN. This release takes place in the central recirculation zone when the coal is first heated up. The continued reaction processes of the HCN take different paths, dependent on whether the burner near field zone is fuel-rich or fuel-lean: Under fuel-rich conditions: HCN {yields} CN {yields} N{sub 2}. Under fuel-lean conditions: HCN {yields} NH/NCO {yields} NO. This reaction scheme is strongly simplified in order to clarify the main influence of the aerodynamics on the NO{sub x} formation. Concentration of radicals O, OH, H are also important for the reaction routes as well as the residence time for the coal particles under respective conditions. The conditions for reactions are however determined largely by the aerodynamics of the near-field burner zone. (orig./GL).

SERS detection of the biomarker hydrogen cyanide from Pseudomonas aeruginosa cultures isolated from cystic fibrosis patients

Science.gov (United States)

Lauridsen, Rikke Kragh; Sommer, Lea M.; Johansen, Helle Krogh; Rindzevicius, Tomas; Molin, Søren; Jelsbak, Lars; Engelsen, Søren Balling; Boisen, Anja

2017-03-01

Pseudomonas aeruginosa is the primary cause of chronic airway infections in cystic fibrosis (CF) patients. Persistent infections are seen from the first P. aeruginosa culture in about 75% of young CF patients, and it is important to discover new ways to detect P. aeruginosa at an earlier stage. The P. aeruginosa biomarker hydrogen cyanide (HCN) contains a triple bond, which is utilized in this study because of the resulting characteristic C≡N peak at 2135 cm-1 in a Raman spectrum. The Raman signal was enhanced by surface-enhanced Raman spectroscopy (SERS) on a Au-coated SERS substrate. After long-term infection, a mutation in the patho-adaptive lasR gene can alter the expression of HCN, which is why it is sometimes not possible to detect HCN in the breath of chronically infected patients. Four P. aeruginosa reference strains and 12 clinical P. aeruginosa strains isolated from CF children were evaluated, and HCN was clearly detected from overnight cultures of all wild type-like isolates and half of the later isolates from the same patients. The clinical impact could be that P. aeruginosa infections could be detected at an earlier stage, because daily breath sampling with an immediate output could be possible with a point-of-care SERS device.

External cavity diode laser-based detection of trace gases with NICE-OHMS using current modulation.

Science.gov (United States)

Centeno, R; Mandon, J; Cristescu, S M; Axner, O; Harren, F J M

2015-03-09

We combine an external cavity diode laser with noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) using current modulation. With a finesse of 1600, we demonstrate noise equivalent absorption sensitivities of 4.1 x 10(-10) cm(-1) Hz(-1/2), resulting in sub-ppbv detection limits for Doppler-broadened transitions of CH(4) at 6132.3 cm(-1), C(2)H(2) at 6578.5 cm(-1) and HCN at 6541.7 cm(-1). The system is used for hydrogen cyanide detection from sweet almonds.

ISOLASI DAN KARAKTERISASI BAKTERI TANAH SAWAH DI DESA SUKAWALI DAN DESA BELIMBING, KABUPATEN TANGERANG

Directory of Open Access Journals (Sweden)

Arief Pambudi

2017-08-01

Full Text Available Abstrak Penggunaan pupuk kimia secara berlebih dapat menyebabkan kerusakan tanah dan menyebabkan ekosistem yang ada didalamnya terganggu. Plant growth-promoting rhizobacteria (PGPR adalah bakteri yang hidup di daerah rizosfer tanaman yang dapat berperan sebagai biofertilizer, biostimulan dan bioprotektan. Penelitian ini bertujuan untuk memperoleh dan mengetahui karakteristik bakteri tanah yang berasal dari dua area persawahan, lokasi pertama di Desa Sukawali (TGR 1 dan lokasi kedua di Desa Belimbing (TGR 2, Kabupaten Tangerang. Penelitian dilakukan dengan mengambil sampel tanah, kemudian sampel dikultur dalam media agar nutrien dengan pengenceran bertingkat. Total bakteri dihitung dan isolat yang diperoleh diuji kemampuan dan karakternya dalam menambat nitrogen (BPN, melarutkan fosfat (BPF, menghasilkan indole acetic acid (IAA, menghasilkan Hidrogen Cyanide (HCN, aktivitas katalase, jenis Gram dan karakter motilitas. Total bakteri yang dapat tumbuh dari kedua lokasi sebanyak 2,4x106 CFU/g dan 1,8x106 CFU/g. Kedua lokasi diperoleh total 45 isolat dengan seluruhnya positif BPN, 42 isolat positif BPF, 24 isolat menghasilkan IAA, 27 isolat menghasilkan HCN, 43 isolat katalase positif, 39 isolat Gram positif, 6 isolat Gram negatif, serta 41 isolat motil. Berdasarkan uji yang dilakukan, terdapat 16 isolat yang berpotensi sebagai pupuk hayati.  Abstract Excessive use of chemical fertilizer may cause soil damage and disturb the ecosystem. Plant growth-promoting rhizobacteria (PGPR is a consortium bacteria that live in plant rhizosphere which acts as biofertilizer, biostimulant, and bioprotectant. The objective of this research is to isolate and investigate the characteristics of soil bacteria originating from two rice fields in Sukawali Village (TGR 1 and Belimbing Village (TGR 2, Tangerang Regency. The research was conducted by collecting soil samples and then culturing the bacteria onto nutrient agar medium with serial dilution. The total bacteria

Hydrogen Cyanide in the Upper Troposphere: GEM-AQ Simulation and Comparison with ACE-FTS Observations

Science.gov (United States)

Lupu, A.; Kaminski, J. W.; Neary, L.; McConnell, J. C.; Toyota, K.; Rinsland, C. P.; Bernath, P. F.; Walker, K. A.; Boone, C. D.; Nagahama, Y.;

The oxidation of hydrogen cyanide and related chemistry

DEFF Research Database (Denmark)

Dagaut, Philippe; Glarborg, Peter; Alzueta, Maria U.

2008-01-01

For modeling the formation of nitrogen oxides in combustion via both the prompt-NO and the fuel-NO mechanisms, as well as for modeling the reduction of nitrogen oxides via reburning, a good knowledge of the kinetics of oxidation of hydrogen cyanide (HCN) is required. The formation routes to HCN a...

Analysis of Major Item Redistribution/Substitution Policies. Volume 2

Science.gov (United States)

1980-05-01

HYu IKItPUIJ le I 113uu1qlesq9d .5 H r Lc1 I/36 L dI I U 4.1 Pc(C-i( F Jumi- ,iEU) 1e,uulu11f!)Vv I I H 4001 PI-1I I F nIALU "IIU l~lUUUei9daeb 1 3...LAl I d󈧭uu ldd11.v 1 I KK4eO9 IN/on1to rC Ft HYU LAI UIL d󈧭UOUIcde11U 1 2K HC-n I n6( 11- L b es/ A U- et41tiu0)4e4dd1 I c!K .5) 9 1 p FlI CAI oF...OULLY HYU ly Il Q910usiblf3o 2 1 .mm .󈧰Ub L VW Af’C UULL MUU Ml y 41 9vvbUt~dv) 1mM L I U Jd L 1 W 3 AC JLY Y Ty1 411Qu 41bUOUI66069 1 4 Li39h.lj’ AKl

Automated no-carrier-added synthesis of [1-11C]-labeled D- and L-enantiomers of lactic acid

International Nuclear Information System (INIS)

Drandarov, Konstantin; Schubiger, P. August; Westera, Gerrit

2006-01-01

The first purely chemical method for automated no-carrier-added synthesis of [1- 11 C]-labeled D(R)- and L(S)-2-hydroxypropanoic acid (lactic acid) was developed for experimental neurophysiology studies and position emission tomography (PET) diagnosis. Starting from sodium 1-hydroxyethanesulfonate and [ 11 C]HCN (trapped as [ 11 C]KCN) the intermediate DL-(R,S)-[1- 11 C]-2-hydroxypropanenitrile was prepared. Its rapid acid hydrolysis gave DL-(R,S)-[1- 11 C]lactic acid, which was isolated by preparative reversed phase HPLC and automatically injected on a second preparative C 18 HPLC column coated with a chiral selector, where both [1- 11 C]lactic acid enantiomers were separated by chiral ligand-exchange chromatography. Two novel chiral selectors for HPLC enantiomeric separation of α-hydroxy acids, namely D(R)- or L(S)-2-amino-3-methyl-3-(5-phenylpentylsulfanyl)-butanoic acid were utilized for the preparative HPLC separation of the [1- 11 C]lactic acid enantiomers. The preparation of the selectors and the coating procedure for the manufacturing of the preparative chiral HPLC columns are described. A highly efficient trap for [ 11 C]HCN is presented. The whole radiosynthesis is automated, takes about 45 min and leads to more than 80% decay corrected overall radiochemical yield of each enantiomer (up to 2.5 GBq) with over 99% radiochemical, chemical and enantiomeric purity. The specific activity at the end of the synthesis is about 400 GBq/μmol

Release of nitrogen precursors from coal and biomass residues in a bubbling fluidized bed

Energy Technology Data Exchange (ETDEWEB)

P. Abelha; I. Gulyurtlu; I. Cabrita [Instituto Nacional de Engenharia, Lisbon (Portugal)

2008-01-15

This work was undertaken with the aim of quantifying the relative amounts of NH{sub 3} and HCN released from different residues during their devolatilization under fluidized bed conditions. The results were compared with data collected for bituminous coals of different origin. The relation between amounts of HCN and NH{sub 3} released and the levels of NOX and N{sub 2}O formed during cocombustion was also addressed. The partitioning of nitrogen between volatiles and char was also quantified. The pyrolysis studies were undertaken in a small fluidized bed reactor of 80 mm of ID and 500 mm high using an inert atmosphere (N{sub 2}). The HCN and NH{sub 3} were quantified by bubbling the pyrolysis gases in absorbing solutions which were subsequently analyzed with selective electrodes. The combustion studies were carried out on a pilot installation. The fluidized bed combustor is square in cross section with each side being 300 mm long. There is secondary air supply to the freeboard at different heights to deal with high volatile fuels as almost all waste materials are. The temperatures in the bed and in the freeboard and that of the flue gases leaving the reactor were continuously monitored. The results obtained suggest that, while coal releases nitrogen mostly as HCN, residues like RDF and sewage sludge give out fuel-N in greater quantities as NH{sub 3}. Residues at fluidized bed combustion (FBC) temperatures release more than 80% of the fuel-N with the volatiles. The NH{sub 3} evolved during pyrolysis acted as a reducing agent on NOX emissions. The presence of calcium significantly reduces the emission of N{sub 2}O probably by interfering with HCN chemistry. With high amounts of residues in the fuel mixture, the relative importance of char on the nitrogen chemistry substantially decreases. By using cocombustion, it is possible to reduce fuel-N conversion to NOX and N{sub 2}O, by tuning the amounts of coal and residue in the mixture. 29 refs., 18 figs., 3 tabs.

Chemical Complexity in Local Diffuse and Translucent Clouds: Ubiquitous Linear C3H and CH3CN, a Detection of HC3N and an Upper Limit on the Abundance of CH2CN

Science.gov (United States)

Liszt, Harvey; Gerin, Maryvonne; Beasley, Anthony; Pety, Jerome

2018-04-01

We present Jansky Very Large Array observations of 20–37 GHz absorption lines from nearby Galactic diffuse molecular gas seen against four cosmologically distant compact radio continuum sources. The main new observational results are that l-C3H and CH3CN are ubiqitous in the local diffuse molecular interstellar medium at {\\text{}}{A}{{V}} ≲ 1, while HC3N was seen only toward B0415 at {\\text{}}{A}{{V}} > 4 mag. The linear/cyclic ratio is much larger in C3H than in C3H2 and the ratio CH3CN/HCN is enhanced compared to TMC-1, although not as much as toward the Horsehead Nebula. More consequentially, this work completes a long-term program assessing the abundances of small hydrocarbons (CH, C2H, linear and cyclic C3H and C3 {{{H}}}2, and C4H and C4H‑) and the CN-bearing species (CN, HCN, HNC, HC3N, HC5N, and CH3CN): their systematics in diffuse molecular gas are presented in detail here. We also observed but did not strongly constrain the abundances of a few oxygen-bearing species, most prominently HNCO. We set limits on the column density of CH2CN, such that the anion CH2CN‑ is only viable as a carrier of diffuse interstellar bands if the N(CH2CN)/N(CH2CN‑) abundance ratio is much smaller in this species than in any others for which the anion has been observed. We argue that complex organic molecules (COMS) are not present in clouds meeting a reasonable definition of diffuse molecular gas, i.e., {\\text{}}{A}{{V}} ≲ 1 mag. Based on observations obtained with the NRAO Jansky Very Large Array (VLA).

Experimental study of rapid brown coal pyrolysis at high temperature

Energy Technology Data Exchange (ETDEWEB)

Qian, Lin; Sun, Shaozeng; Meng, Shun; Meng, Xianyu; Guo, Yangzhou [Harbin Institute of Technology, Harbin (China). Combustion Engineering Research Inst.

2013-07-01

Rapid coal pyrolysis is a very important step in the early stage of combustion. Rapid pyrolysis experiments of a brown coal at high temperature have been studied on a laminar drop tube furnace. The volatile mass release measured in this study is high for low rank coal. The activation energy and pre-exponential factor of pyrolysis are 19901.22 kJ/mol and 102.71, respectively. The nitrogen distribution between volatile and char is 0.54. With the increase of temperature, the yields of NH{sub 3} decreases, while those of HCN increases, leading the value of HCN/NH{sub 3} to become larger. At high temperature, the main nitrogen- containing species of pyrolysis in volatile is HCN.

Cryocopolimerization of hydrogen cyanide with acetaldehyde

International Nuclear Information System (INIS)

Kiryukhin, D.P.; Kichigina, G.A.; Mozhaev, P.S.; Barkalov, I.M.

1997-01-01

Calorimetric technique was used to study in detail the phase state of the HCN-acetaldehyde system. The initiation of copolymerization occurs throughout the whole range of initial concentrations of monomers in the process of defrosting the system radiolyzed at 77 K in the regions of enhanced molecular mobility. The HCN component in the copolymer monotonously increases with an increase in the concentration of this comonomer in the starting mixture. The system passes completely to a glassy state with ∼25% molar of HCN. The completely soluble copolymer is formed only if the process is carried out in the system of this kind. The copolymerization in the glassy system occurs by cationic and radical mechanism

Ion cyclotron resonance study of reactions of ions with hydrogen atoms

International Nuclear Information System (INIS)

Karpas, Z.; Anicich, V.; Huntress, W.T. Jr.

1979-01-01

Reactions of H 2 + , HeH + , and CO 2 + ions with hydrogen atoms, and the reactions of D 2 + , CO 2 + , CO + , N 2 + and HCN + with deuterium atoms, were studied using ion cyclotron resonance techniques. These reactions proceed predominantly via a charge transfer mechanism. The rate constants measured are: 6.4, 9.1, 1.1, 5.0, 0.84, 0.90, 1.2, and 0.37 x 10 -10 cm 3 /sec, respectively. Hydrocarbon ions of the types CH/sub n/ + and C 2 H/sub n/ + , where n=2--4, do not react with H or D atoms

The rate constant of the reaction NCN + H2 and its role in NCN and NO modeling in low pressure CH4/O2/N2-flames.

Science.gov (United States)

Faßheber, Nancy; Lamoureux, Nathalie; Friedrichs, Gernot

2015-06-28

Bimolecular reactions of the NCN radical play a key role in modeling prompt-NO formation in hydrocarbon flames. The rate constant of the so-far neglected reaction NCN + H2 has been experimentally determined behind shock waves under pseudo-first order conditions with H2 as the excess component. NCN3 thermal decomposition has been used as a quantitative high temperature source of NCN radicals, which have been sensitively detected by difference UV laser absorption spectroscopy at [small nu, Greek, tilde] = 30383.11 cm(-1). The experiments were performed at two different total densities of ρ≈ 4.1 × 10(-6) mol cm(-3) and ρ≈ 7.4 × 10(-6) mol cm(-3) (corresponding to pressures between p = 324 mbar and p = 1665 mbar) and revealed a pressure independent reaction. In the temperature range 1057 K rate constant can be represented by the Arrhenius expression k/(cm(3) mol(-1) s(-1)) = 4.1 × 10(13) exp(-101 kJ mol(-1)/RT) (Δlog k = ±0.11). The pressure independent reaction as well as the measured activation energy is consistent with a dominating H abstracting reaction channel yielding the products HNCN + H. The reaction NCN + H2 has been implemented together with a set of reactions for subsequent HNCN and HNC chemistry into the detailed GDFkin3.0_NCN mechanism for NOx flame modeling. Two fuel-rich low-pressure CH4/O2/N2-flames served as examples to quantify the impact of the additional chemical pathways. Although the overall NCN consumption by H2 remains small, significant differences have been observed for NO yields with the updated mechanism. A detailed flux analysis revealed that HNC, mainly arising from HCN/HNC isomerization, plays a decisive role and enhances NO formation through a new HNC → HNCO → NH2→ NH → NO pathway.

Drift-tube studies of ion-molecule reactions at low collision energies

International Nuclear Information System (INIS)

Chatterjee, B.K.

1988-01-01

This thesis presents experimental studies of ion-molecule reactions at low collision energies using two drift tube mass spectrometer apparatus. The reactions studied are (i) proton transfer from HeH + to ArH + , (ii) charge and ion transfer reactions of O 2 2+ with NO, CO 2 , Ne and O 2 + ( 4 π u ) with CO 2 , (iii) oxidation reactions of Zr + and ZrO + with NO, CO 2 and O 2 , (iv) vibrational quenching reactions of H 3 + with He, (v) termolecular clustering reactions of H 2 CN + and H 2 CN + (HCN) (with He as the third body), (vi) three body association reactions of H + and D + with He (with He as the third body) and (vii) termolecular association reaction of NO + with NO (with Ne as third body). All the reactions were studied at thermal energies (at room temperature), reactions of O 2 2+ with NO and CO 2 , Zr + with NO/CO 2 /O 2 were also studied at center-of-mass energies higher than thermal and the association reactions of H 2 CN + /H 2 CN + (HCN) with HCN and H + /D + with He were studied at low temperatures. In addition, the thesis presents model calculations for the sweep-out effect which is an instrumental effect. A super Langevin rate constant is introduced which is a higher-order correction to the Langevin model. A theoretical model for the three-body ion-atom association rate constant is presented in the appendix of the thesis

Aplikasi Isolat Bakteri Indigenous Ubi Kayu Karet (Manihot glaziovii pada Fermentasi Pembuatan Mocaf

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K Kamsina

2017-12-01

Full Text Available Indigenous bacteria isolate of cassava rubber (Manihot glaziovii is an isolate of native bacteria which is available in rubber cassava tubers. Rubber cassava tuber is a cassava with a high content of cyanide acid (HCN. The study was aimed to see the ability of indigenous bacteria isolate of cassava cultivar rubber (BUG1 on mocaf making fermentation. This study used a completely randomized design with treatments (A addition of starter indigenous bacteria isolates of rubber variety (BUG1, (B without isolates, and (C without  fermentation. The resulting mocaf product was conducted a chemical tests consisted of moisture, ash, starch, acid degree, coarse fiber, and HCN content, while organoleptic tests consisted of color, aroma, and texture. The analysis results on the various treatments showed that the optimal treatment of mocaf flour produced was the addition of indigenous bacteria isolate starter of rubber variety (BUG1.ABSTRAKIsolat bakteri indigenous ubi kayu karet (Manihot glaziovii merupakan isolat bakteri asli yang berada dalam umbi ubi kayu karet. Ubi kayu kultivar  karet merupakan ubi kayu dengan kandungan asam sianida (HCN tinggi. Penelitian bertujuan untuk mempelajari kemampuan isolat bakteri indigenous ubi kayu kultivar karet (BUG1 pada fermentasi pembuatan mocaf. Penelitian ini menggunakan rancangan acak lengkap (RAL dengan perlakuan (A pemberian starter isolat bakteri indigenous varietas karet (BUG1, (B tanpa isolat, dan (C tanpa fermentasi. Terhadap produk mocaf  yang dihasilkan dilakukan uji kimia meliputi kadar air,  abu, pati, derajat asam, serat kasar, dan kadar HCN, sedangkan uji organoleptik meliputi warna, aroma, dan tekstur. Hasil analisis terhadap berbagai perlakuan menunjukkan perlakuan optimal untuk tepung mocaf  yang dihasilkan adalah pemberian starter isolat bakteri indigenous varietas karet (BUG1.

Genetic Perturbations Suggest a Role of the Resting Potential in Regulating the Expression of the Ion Channels of the KCNA and HCN families in Octopus Cells of the Ventral Cochlear Nucleus

Science.gov (United States)

Cao, Xiao-Jie; Oertel, Donata

2017-01-01

Low-voltage-activated K+ (gKL) and hyperpolarization-activated mixed cation conductances (gh) mediate currents, IKL and Ih, through channels of the Kv1 (KCNA) and HCN families respectively and give auditory neurons the temporal precision required for signaling information about the onset, fine structure, and time of arrival of sounds. Being partially activated at rest, gKL and gh contribute to the resting potential and shape responses to even small subthreshold synaptic currents. Resting gKL and gh also affect the coupling of somatic depolarization with the generation of action potentials. To learn how these important conductances are regulated we have investigated how genetic perturbations affect their expression in octopus cells of the ventral cochlear nucleus (VCN). We report five new findings: First, the magnitude of gh and gKL varied over more than two-fold between wild type strains of mice. Second, average resting potentials are not different in different strains of mice even in the face of large differences in average gKL and gh. Third, IKL has two components, one being α-dendrotoxin (α-DTX)-sensitive and partially inactivating and the other being α-DTX-insensitive, tetraethylammonium (TEA)-sensitive, and non-inactivating. Fourth, the loss of Kv1.1 results in diminution of the α-DTX-sensitive IKL, and compensatory increased expression of an α-DTX-insensitive, tetraethylammonium (TEA)-sensitive IKL. Fifth, Ih and IKL are balanced at the resting potential in all wild type and mutant octopus cells even when resting potentials vary in individual cells over nearly 10 mV, indicating that the resting potential influences the expression of gh and gKL. The independence of resting potentials on gKL and gh shows that gKL and gh do not, over days or weeks, determine the resting potential but rather that the resting potential plays a role in regulating the magnitude of either or both gKL and gh. PMID:28065805

Emissions from forest fires near Mexico City

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R. J. Yokelson

2007-11-01

Full Text Available The emissions of NO_x (defined as NO (nitric oxide + NO₂ (nitrogen dioxide and hydrogen cyanide (HCN, per unit amount of fuel burned, from fires in the pine forests that dominate the mountains surrounding Mexico City (MC are about 2 times higher than normally observed for forest burning. The ammonia (NH₃ emissions are about average for forest burning. The upper limit for the mass ratio of NO_x to volatile organic compounds (VOC for these MC-area mountain fires was ~0.38, which is similar to the NO_x/VOC ratio in the MC urban area emissions inventory of 0.34, but much larger than the NO_x/VOC ratio for tropical forest fires in Brazil (~0.068. The nitrogen enrichment in the fire emissions may be due to deposition of nitrogen-containing pollutants in the outflow from the MC urban area. This effect may occur worldwide wherever biomass burning coexists with large urban areas (e.g. the tropics, southeastern US, Los Angeles Basin. The molar emission ratio of HCN to carbon monoxide (CO for the mountain fires was 0.012±0.007, which is 2–9 times higher than widely used literature values for biomass burning. The ambient molar ratio HCN/CO in the MC-area outflow is about 0.003±0.0003. Thus, if only mountain fires emit significant amounts of HCN, these fires may be contributing about 25% of the CO production in the MC-area (~98–100 W and 19–20 N. Comparing the PM₁₀/CO and PM_2.5/CO mass ratios in the MC Metropolitan Area emission inventory (0.0115 and 0.0037 to the PM1/CO mass ratio for the mountain fires (0.133 then suggests that these fires could produce as much as ~79–92% of the primary fine particle mass generated in the MC-area. Considering both the uncertainty in the HCN/CO ratios and secondary aerosol formation in the urban and fire emissions implies that about 50±30% of the "aged" fine particle mass in the March 2006 MC-area outflow could be from these fires.

Cyanogenic glucoside patterns in sweet and bitter almonds

DEFF Research Database (Denmark)

Sánchez Pérez, Raquel; Møller, Birger Lindberg; Olsen, Carl Erik

2009-01-01

When an almond (Prunus dulcis (Mill.) D. A. Webb) kernel containing cyanogenic glucosides (prunasin or amygdalin) is disintegrated, the glucosides will typically be hydrolyzed by amygdalin hydrolase, prunasin hydrolase, and mandelonitrile lyase with concomitant release of glucose, benzaldehyde......, and hydrogen cyanide (HCN). Benzaldehyde and HCN, in low amounts, provide the characteristic almond taste and flavour. Because of the toxicity of HCN, low cyanogenic glucoside content in the kernel is a prime breeding target. Biochemical analyses of different almond tissues were carried out to investigate...... their ability to synthesize and degrade prunasin and amygdalin. The analyses were carried out during the entire growth season, from almond tree flowering to kernel ripening using the following tissues: leaves, petioles, and the fruit (endosperm and cotyledon). Four different genotypes were investigated...

The role of char and tar in determining the gas-phase partitioning of nitrogen during biomass gasification

International Nuclear Information System (INIS)

Broer, Karl M.; Brown, Robert C.

2015-01-01

Highlights: • Switchgrass was gasified at an equivalence ratio of zero and 650–850 °C. • Short residence times were employed to minimize secondary reactions. • Char- and tar-bound nitrogen, NH_3, HCN, and N_2 were all significant products. • Increasing temperature leads to increased release of gaseous nitrogen compounds. • Kinetic models of gasification should include nitrogen release from char and tar. - Abstract: Gasification is an attractive option for converting biomass into fuels and chemicals. Most biomass contains significant amounts of fuel-bound nitrogen (FBN), which partially converts into ammonia (NH_3) and hydrogen cyanide (HCN) during gasification. These nitrogen compounds are problematic as they can lead to NO_X emissions or catalyst poisoning in downstream applications of syngas. FBN can convert to other products as well, including diatomic nitrogen (N_2), char-bound nitrogen (char-N), and tar-bound nitrogen (tar-N). Efforts to predict concentrations of NH_3 and HCN have been hindered by a lack of accurate, comprehensive measurements of nitrogen partitioning among gasification products. The present study gasified switchgrass under allothermal, short residence time conditions and measured NH_3, HCN, char-N, and tar-N as a function of temperature in the range of 650–850 °C with diatomic nitrogen determined by difference. It was found that a major portion of FBN was retained in the char and tar products. As temperature was increased, char and tar were consumed, releasing nitrogen as gaseous NH_3 and HCN. This increase in undesirable nitrogen compounds is contrary to the predictions of most gasification models, which overlook the presence of significant nitrogen in char and tar even if they include tar cracking and char gasification reactions. The results of this study demonstrate that gas-phase reactions alone are not sufficient to predict the fate of nitrogen during gasification. In order for modeling efforts to obtain more accurate

Pyrrolnitrin and Hydrogen Cyanide Production by Pseudomonas chlororaphis Strain PA23 Exhibits Nematicidal and Repellent Activity against Caenorhabditis elegans.

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Munmun Nandi

Full Text Available Pseudomonas chlororaphis strain PA23 is a biocontrol agent able to suppress growth of the fungal pathogen Sclerotinia sclerotiorum. This bacterium produces an arsenal of exometabolites including pyrrolnitrin (PRN, phenazine (PHZ, hydrogen cyanide (HCN, and degradative enzymes. Production of these compounds is controlled at both the transcriptional and posttranscriptional levels by the Gac-Rsm system, RpoS, PsrA, and the Phz quorum-sensing system. Beyond pathogen-suppression, the success of a biocontrol agent is dependent upon its ability to establish itself in the environment where predation by bacterivorous organisms, including nematodes, may threaten persistence. The focus of this study was to investigate whether PA23 is able to resist grazing by Caenorhabditis elegans and to define the role played by exoproducts in the bacterial-nematode interaction. We discovered that both PRN and HCN contribute to fast- and slow-killing of C. elegans. HCN is well-established as having lethal effects on C. elegans; however, PRN has not been reported to be nematicidal. Exposure of L4 stage nematodes to purified PRN reduced nematode viability in a dose-dependent fashion and led to reduced hatching of eggs laid by gravid adults. Because bacterial metabolites can act as chemoattractants or repellents, we analyzed whether PA23 exhibited attractant or repulsive properties towards C. elegans. Both PRN and HCN were found to be potent repellents. Next we investigated whether the presence of C. elegans would elicit changes in PA23 gene activity. Co-culturing the two organisms increased expression of a number of genes associated with biocontrol, including phzA, hcnA, phzR, phzI, rpoS and gacS. Exoproduct analysis showed that PHZ and autoinducer signals were upregulated, consistent with the gene expression profiles. Collectively, these findings indicate that PA23 is able to sense the presence of C. elegans and it is able to both repel and kill the nematodes, which

Automated no-carrier-added synthesis of [1-{sup 11}C]-labeled D- and L-enantiomers of lactic acid

Energy Technology Data Exchange (ETDEWEB)

Drandarov, Konstantin [Center for Radiopharmaceutical Sciences, Swiss Federal Institute of Technology Zurich, University Hospital Zuerich, CH-8091 Zurich (Switzerland); Paul Scherrer Institute, CH-5232 Villigen (Switzerland); Schubiger, P. August [Center for Radiopharmaceutical Sciences, Swiss Federal Institute of Technology Zurich, University Hospital Zuerich, CH-8091 Zurich (Switzerland); Paul Scherrer Institute, CH-5232 Villigen (Switzerland); Westera, Gerrit [Center for Radiopharmaceutical Sciences, Swiss Federal Institute of Technology Zurich, University Hospital Zuerich, CH-8091 Zurich (Switzerland) and Paul Scherrer Institute, CH-5232 Villigen (Switzerland)]. E-mail: gerrit.westera@usz.ch

2006-12-15

The first purely chemical method for automated no-carrier-added synthesis of [1-{sup 11}C]-labeled D(R)- and L(S)-2-hydroxypropanoic acid (lactic acid) was developed for experimental neurophysiology studies and position emission tomography (PET) diagnosis. Starting from sodium 1-hydroxyethanesulfonate and [{sup 11}C]HCN (trapped as [{sup 11}C]KCN) the intermediate DL-(R,S)-[1-{sup 11}C]-2-hydroxypropanenitrile was prepared. Its rapid acid hydrolysis gave DL-(R,S)-[1-{sup 11}C]lactic acid, which was isolated by preparative reversed phase HPLC and automatically injected on a second preparative C{sub 18} HPLC column coated with a chiral selector, where both [1-{sup 11}C]lactic acid enantiomers were separated by chiral ligand-exchange chromatography. Two novel chiral selectors for HPLC enantiomeric separation of {alpha}-hydroxy acids, namely D(R)- or L(S)-2-amino-3-methyl-3-(5-phenylpentylsulfanyl)-butanoic acid were utilized for the preparative HPLC separation of the [1-{sup 11}C]lactic acid enantiomers. The preparation of the selectors and the coating procedure for the manufacturing of the preparative chiral HPLC columns are described. A highly efficient trap for [{sup 11}C]HCN is presented. The whole radiosynthesis is automated, takes about 45 min and leads to more than 80% decay corrected overall radiochemical yield of each enantiomer (up to 2.5 GBq) with over 99% radiochemical, chemical and enantiomeric purity. The specific activity at the end of the synthesis is about 400 GBq/{mu}mol.

Disentangling the Circumnuclear Environs of Centaurus A. III. An Inner Molecular Ring, Nuclear Shocks, and the CO to Warm H{sub 2} Interface

Energy Technology Data Exchange (ETDEWEB)

Espada, D.; Miura, R. E.; Iono, D. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Matsushita, S. [Academia Sinica, Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China); Israel, F. P. [Sterrewacht Leiden, Leiden University, P.O. Box 9513, 2300 RA, Leiden (Netherlands); Neumayer, N. [Max Planck Institute for Astronomy (MPIA), Königstuhl 17, D-69121 Heidelberg (Germany); Martin, S. [Joint ALMA Observatory, Alonso de Córdova, 3107, Vitacura, Santiago 763-0355 (Chile); Henkel, C. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121, Bonn (Germany); Izumi, T.; Kohno, K. [Institute of Astronomy, School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Aalto, S. [Department of Earth and Space Sciences, Chalmers University (Sweden); Ott, J. [National Radio Astronomy Observatory, Socorro, NM (United States); Peck, A. B. [Gemini Observatory, 670 N’Aohoku Pl, Hilo 96720-2700, Hawaii, HI (United States); Quillen, A. C. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States)

2017-07-10

We present the distribution and kinematics of the molecular gas in the circumnuclear disk (CND; 400 pc × 200 pc) of Centaurus A with resolutions of ∼5 pc (0.″3) and shed light onto the mechanism feeding the active galactic nucleus (AGN) using CO(3–2), HCO{sup +}(4–3), HCN(4–3), and CO(6–5) observations obtained with ALMA. Multiple filaments or streamers of tens to a hundred parsec scale exist within the CND, which form a ring-like structure with an unprojected diameter of 9″ × 6″ (162 pc × 108 pc) and a position angle P.A. ≃ 155°. Inside the nuclear ring, there are two leading and straight filamentary structures with lengths of about 30–60 pc at P.A. ≃ 120° on opposite sides of the AGN, with a rotational symmetry of 180° and steeper position–velocity diagrams, which are interpreted as nuclear shocks due to non-circular motions. Along the filaments, and unlike other nearby AGNs, several dense molecular clumps present low HCN/HCO{sup +}(4–3) ratios (≲0.5). The filaments abruptly end in the probed transitions at r ≃ 20 pc from the AGN, but previous near-IR H{sub 2}( J = 1–0)S(1) maps show that they continue in an even warmer gas phase ( T ∼ 1000 K), winding up in the form of nuclear spirals, and forming an inner ring structure with another set of symmetric filaments along the N–S direction and within r ≃ 10 pc. The molecular gas is governed primarily by non-circular motions, being the successive shock fronts at different scales where loss of angular momentum occurs, a mechanism that may feed efficiently powerful radio galaxies down to parsec scales.

The Composition of Comet C/2009 PI (Garradd) from Infrared Spectroscopy: Evidence for an Oxygen-Rich Heritage?

Science.gov (United States)

DiSanti, M. A.; Bonev, B. P.; Villanueva, G. L.; Paganini, L.; Mumma, M. J.; Charnley, S. B.; Keane, J. V.; Meech, K. J.; Blake, G. A.; Boehnhardt, H.;

Corona discharge experiments in admixtures of N{sub 2} and CH{sub 4}: a laboratory simulation of Titan's atmosphere

Energy Technology Data Exchange (ETDEWEB)

Horvath, G; Skalny, J D; Klas, M; Zahoran, M [Department of Experimental Physics, Comenius University, Mlynska dolina F-2, 842 48 Bratislava (Slovakia); Mason, N J [Department of Physics and Astronomy, The Open University, Walton Hall, MK7 6AA, Milton Keynes (United Kingdom); Vladoiu, R; Manole, M [Ovidius University Constanta, B - dul Mamaia 124, 900527 Constanta (Romania)], E-mail: horeszka@gmail.com

2009-08-15

A positive corona discharge fed by a N{sub 2} : CH{sub 4} mixture (98 : 2) at atmospheric pressure and ambient temperature has been studied as a laboratory mimic of the chemical processes occurring in the atmosphere of Titan, Saturn's largest moon. In situ measurements of UV and IR transmission spectra within the discharge have shown that the main chemical product is C{sub 2}H{sub 2}, produced by dissociation of CH{sub 4}, with small but significant traces of ethane and HCN, all species that have been detected in Titan's atmosphere. A small amount (0.2%) of CH{sub 4} was decomposed after 12 min of treatment requiring an average energy of 2.7 kWh g{sup -1}. After 14 min the discharge was terminated due to the formation of a solid yellow deposit on the central wire electrode. Such a deposit is similar to that observed in other discharges and is believed to be an analogue of the aerosol and dust observed in Titan's atmosphere and is composed of chemical species commonly known as 'tholins'. We have also explored the electrical properties of the discharge. The admixture of methane into nitrogen caused an increase in the onset voltage of the discharge and consequently led to a reduction in the measured discharge current.

Spectroscopic investigations of plasma nitriding processes: A comparative study using steel and carbon as active screen materials

Science.gov (United States)

Hamann, S.; Burlacov, I.; Spies, H.-J.; Biermann, H.; Röpcke, J.

2017-04-01

Low-pressure pulsed DC H2-N2 plasmas were investigated in the laboratory active screen plasma nitriding monitoring reactor, PLANIMOR, to compare the usage of two different active screen electrodes: (i) a steel screen with the additional usage of CH4 as carbon containing precursor in the feeding gas and (ii) a carbon screen without the usage of any additional gaseous carbon precursor. Applying the quantum cascade laser absorption spectroscopy, the evolution of the concentration of four stable molecular species, NH3, HCN, CH4, and C2H2, has been monitored. The concentrations were found to be in a range of 1012-1016 molecules cm-3. By analyzing the development of the molecular concentrations at variations of the screen plasma power, a similar behavior of the monitored reaction products has been found for both screen materials, with NH3 and HCN as the main reaction products. When using the carbon screen, the concentration of HCN and C2H2 was 30 and 70 times higher, respectively, compared to the usage of the steel screen with an admixture of 1% CH4. Considering the concentration of the three detected hydrocarbon reaction products, a combustion rate of the carbon screen of up to 69 mg h-1 has been found. The applied optical emission spectroscopy enabled the determination of the rotational temperature of the N2+ ion which has been in a range of 650-900 K increasing with the power in a similar way in the plasma of both screens. Also with power the ionic component of nitrogen molecules, represented by the N2+ (0-0) band of the first negative system, as well as the CN (0-0) band of the violet system increase strongly in relation to the intensity of the neutral nitrogen component, i.e., the N2 (0-0) band of the second positive system. In addition, steel samples have been treated with both the steel and the carbon screen resulting in a formation of a compound layer of up to 10 wt. % nitrogen and 10 wt. % carbon, respectively, depending on the screen material.