Sample records for hcn2 hcn4 kcne1

  1. Long-lasting spatial learning and memory impairments caused by chronic cerebral hypoperfusion associate with a dynamic change of HCN1/HCN2 expression in hippocampal CA1 region.

    PubMed

    Luo, Pan; Lu, Yun; Li, Changjun; Zhou, Mei; Chen, Cheng; Lu, Qing; Xu, Xulin; He, Zhi; Guo, Lianjun

    2015-09-01

    Chronic cerebral hypoperfusion (CCH) causes learning and memory impairments and increases the risk of Alzheimer disease (AD) and vascular dementia (VD) through several biologically plausible pathways, yet the mechanisms underlying the disease process remained unclear particularly in a temporal manner. We performed permanent bilateral occlusion of the common carotid arteries (two-vessel occlusion, 2VO) to induce CCH. To determine whether hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are altered at different stages of cognitive impairment caused by CCH, adult male SD rats were randomly distributed into sham-operated 4, 8 and 12weeks group, 2VO 4, 8 and 12weeks group. Learning and memory performance were evaluated with Morris water maze (MWM) and long-term potentiation (LTP) was used to address the underlying synaptic mechanisms. Expression of NeuN, HCN1 and HCN2 in hippocampal CA1, DG and CA3 areas was quantified by immunohistochemistry and western blotting. Our data showed that CCH induced a remarkable spatial learning and memory deficits in rats of 2VO 4, 8, and 12weeks group although neuronal loss only occurred after 4weeks of 2VO surgery in CA1. In addition, a significant reduction of HCN1 surface expression in CA1 was observed in the group that suffered 4weeks ischemia but neither 8 nor 12weeks. However, HCN2 surface expression in CA1 increased throughout the ischemia time-scales (4, 8 and 12w). Our findings indicate spatial learning and memory deficits in the CCH model are associated with disturbed HCN1 and HCN2 surface expression in hippocampal CA1. The altered patterns of both HCN1 and HCN2 surface expression may be implicated in the early stage (4w) of spatial learning and memory impairments; and the stable and long-lasting impairments of spatial learning and memory may partially attribute to the up-regulated HCN2 surface expression. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. The expression of hyperpolarization-activated cyclic nucleotide-gated channel 1 (HCN1) and HCN2 in the rat trigeminal ganglion, sensory root, and dental pulp.

    PubMed

    Cho, Y S; Kim, Y S; Moozhayil, S J; Yang, E S; Bae, Y C

    2015-04-16

    Hyperpolarization-activated cyclic nucleotide-gated channel 1 (HCN1) and 2 (HCN2) are abundantly expressed in primary sensory neurons and contribute to neuronal excitability and pathological pain. We studied the expression of HCN1 and HCN2 in the rat trigeminal ganglion (TG) neurons and axons in the dental pulp, and the changes in their expression following inflammation, using light- and electron-microscopic immunocytochemistry and quantitative analysis. HCN1 and HCN2 were expressed predominantly in large-sized, neurofilament 200-immunopositive (+) or parvalbumin+ soma in the TG whereas they were expressed mostly in unmyelinated and small myelinated axons in the sensory root. The expression was particularly strong along the plasma membrane in the soma. In the dental pulp, majority of HCN1+ and HCN2+ axons coexpressed calcitonin gene-related peptide. They were expressed mainly in the peripheral pulp and pulp horn where the axons branch extensively in the dental pulp. The expression of HCN1 and HCN2 in TG neurons increased significantly in rats with experimentally induced inflammation of the dental pulp. Our findings support the notion that HCN1 and HCN2 are expressed mainly by both the soma of mechanosensitive neurons in the TG and peripheral axons of nociceptive neurons in the sensory root, and may play a role in the mechanisms of inflammatory pain from the dental pulp. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  3. Flavonoid Regulation of HCN2 Channels*

    PubMed Central

    Carlson, Anne E.; Rosenbaum, Joel C.; Brelidze, Tinatin I.; Klevit, Rachel E.; Zagotta, William N.

    2013-01-01

    The hyperpolarization-activated cyclic nucleotide-modulated (HCN) channels are pacemaker channels whose currents contribute to rhythmic activity in the heart and brain. HCN channels open in response to hyperpolarizing voltages, and the binding of cAMP to their cyclic nucleotide-binding domain (CNBD) facilitates channel opening. Here, we report that, like cAMP, the flavonoid fisetin potentiates HCN2 channel gating. Fisetin sped HCN2 activation and shifted the conductance-voltage relationship to more depolarizing potentials with a half-maximal effective concentration (EC50) of 1.8 μm. When applied together, fisetin and cAMP regulated HCN2 gating in a nonadditive fashion. Fisetin did not potentiate HCN2 channels lacking their CNBD, and two independent fluorescence-based binding assays reported that fisetin bound to the purified CNBD. These data suggest that the CNBD mediates the fisetin potentiation of HCN2 channels. Moreover, binding assays suggest that fisetin and cAMP partially compete for binding to the CNBD. NMR experiments demonstrated that fisetin binds within the cAMP-binding pocket, interacting with some of the same residues as cAMP. Together, these data indicate that fisetin is a partial agonist for HCN2 channels. PMID:24085296

  4. Regulation of human cardiac potassium channels by full-length KCNE3 and KCNE4.

    PubMed

    Abbott, Geoffrey W

    2016-12-06

    Voltage-gated potassium (Kv) channels comprise pore-forming α subunits and a multiplicity of regulatory proteins, including the cardiac-expressed and cardiac arrhythmia-linked transmembrane KCNE subunits. After recently uncovering novel, N-terminally extended (L) KCNE3 and KCNE4 isoforms and detecting their transcripts in human atrium, reported here are their functional effects on human cardiac Kv channel α subunits expressed in Xenopus laevis oocytes. As previously reported for short isoforms KCNE3S and KCNE4S, KCNE3L inhibited hERG; KCNE4L inhibited Kv1.1; neither form regulated the HCN1 pacemaker channel. Unlike KCNE4S, KCNE4L was a potent inhibitor of Kv4.2 and Kv4.3; co-expression of cytosolic β subunit KChIP2, which regulates Kv4 channels in cardiac myocytes, partially relieved Kv4.3 but not Kv4.2 inhibition. Inhibition of Kv4.2 and Kv4.3 by KCNE3L was weaker, and its inhibition of Kv4.2 abolished by KChIP2. KCNE3L and KCNE4L also exhibited subunit-specific effects on Kv4 channel complex inactivation kinetics, voltage dependence and recovery. Further supporting the potential physiological significance of the robust functional effects of KCNE4L on Kv4 channels, KCNE4L protein was detected in human atrium, where it co-localized with Kv4.3. The findings establish functional effects of novel human cardiac-expressed KCNE isoforms and further contribute to our understanding of the potential mechanisms influencing cardiomyocyte repolarization.

  5. Sick sinus syndrome in HCN1-deficient mice.

    PubMed

    Fenske, Stefanie; Krause, Stefanie C; Hassan, Sami I H; Becirovic, Elvir; Auer, Franziska; Bernard, Rebekka; Kupatt, Christian; Lange, Philipp; Ziegler, Tilman; Wotjak, Carsten T; Zhang, Henggui; Hammelmann, Verena; Paparizos, Christos; Biel, Martin; Wahl-Schott, Christian A

    2013-12-17

    Sinus node dysfunction (SND) is a major clinically relevant disease that is associated with sudden cardiac death and requires surgical implantation of electric pacemaker devices. Frequently, SND occurs in heart failure and hypertension, conditions that lead to electric instability of the heart. Although the pathologies of acquired SND have been studied extensively, little is known about the molecular and cellular mechanisms that cause congenital SND. Here, we show that the HCN1 protein is highly expressed in the sinoatrial node and is colocalized with HCN4, the main sinoatrial pacemaker channel isoform. To characterize the cardiac phenotype of HCN1-deficient mice, a detailed functional characterization of pacemaker mechanisms in single isolated sinoatrial node cells, explanted beating sinoatrial node preparation, telemetric in vivo electrocardiography, echocardiography, and in vivo electrophysiology was performed. On the basis of these experiments we demonstrate that mice lacking the pacemaker channel HCN1 display congenital SND characterized by bradycardia, sinus dysrhythmia, prolonged sinoatrial node recovery time, increased sinoatrial conduction time, and recurrent sinus pauses. As a consequence of SND, HCN1-deficient mice display a severely reduced cardiac output. We propose that HCN1 stabilizes the leading pacemaker region within the sinoatrial node and hence is crucial for stable heart rate and regular beat-to-beat variation. Furthermore, we suggest that HCN1-deficient mice may be a valuable genetic disease model for human SND.

  6. Rotational excitation of HCN by para- and ortho-H{sub 2}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vera, Mario Hernández, E-mail: marhvera@gmail.com; InSTEC, Quinta de Los Molinos, Plaza, La Habana 10600; Kalugina, Yulia

    Rotational excitation of the hydrogen cyanide (HCN) molecule by collisions with para-H{sub 2}( j = 0, 2) and ortho-H{sub 2}( j = 1) is investigated at low temperatures using a quantum time independent approach. Both molecules are treated as rigid rotors. The scattering calculations are based on a highly correlated ab initio 4-dimensional (4D) potential energy surface recently published. Rotationally inelastic cross sections among the 13 first rotational levels of HCN were obtained using a pure quantum close coupling approach for total energies up to 1200 cm{sup −1}. The corresponding thermal rate coefficients were computed for temperatures ranging from 5 to 100 K.more » The HCN rate coefficients are strongly dependent on the rotational level of the H{sub 2} molecule. In particular, the rate coefficients for collisions with para-H{sub 2}( j = 0) are significantly lower than those for collisions with ortho-H{sub 2}( j = 1) and para-H{sub 2}( j = 2). Propensity rules in favor of even Δj transitions were found for HCN in collisions with para-H{sub 2}( j = 0) whereas propensity rules in favor of odd Δj transitions were found for HCN in collisions with H{sub 2}( j ⩾ 1). The new rate coefficients were compared with previously published HCN-para-H{sub 2}( j = 0) rate coefficients. Significant differences were found due the inclusion of the H{sub 2} rotational structure in the scattering calculations. These new rate coefficients will be crucial to improve the estimation of the HCN abundance in the interstellar medium.« less

  7. Characterization of solvated electrons in hydrogen cyanide clusters: (HCN)n- (n=3, 4)

    NASA Astrophysics Data System (ADS)

    Wu, Di; Li, Ying; Li, Zhuo; Chen, Wei; Li, Zhi-Ru; Sun, Chia-Chung

    2006-02-01

    Theoretical studies of the solvated electrons (HCN)n- (n =3, 4) reveal a variety of electron trapping possibilities in the (HCN)n (n =3, 4) clusters. Two isomers for (HCN)3- and four isomers for (HCN)4- are obtained at the MP2/aug -cc-pVDZ+dBF (diffusive bond functions) level of theory. In view of vertical electron detachment energies (VDEs) at the CCSD(T) level, the excess electron always "prefers" locating in the center of the system, i.e., the isomer with higher coordination number shows larger VDE value. However, the most stable isomers of the solvated electron state (HCN)3- and (HCN)4- are found to be the linear C∞ν and D∞h structures, respectively, but not the fullyl symmetric structures which have the largest VDE values.

  8. [Inhibition of HCN1 channels by ketamine accounts for its antidepressant actions].

    PubMed

    Li, Jing; Chen, Feng-feng; Chen, Xiang-dong; Zhou, Cheng

    2014-11-01

    To investigate the roles of hyperolarization-actived cyclic nucleotide-gated channels 1 (HCN1) in antidepressant actions of ketamine (KET). Male HCN1 knock out (HCN1-/- ) and wildtype (HCN1+/+ ) C57BL6 mice (8-12 weeks, 20-25 g) were chosen. The depression model of mice was developed by continuously oral administration of low dosage of corticosterone (CORT). The immobility time in forced swimming tests (FST) was used to assess the depressive state of mice. Then the two genotype depressive mice were treated with single intraperitoneal injection of 5 mg/kg ketamine (KET group, n=7) or same volume of normal saline (NS group, n=7) respectively. After treatment, the immobility time at 30 min, 24 h and 7 d after the intraperitoneal injection of ketamine or normal saline in CORT-treated mice were compared. In addition, normal HCN1-/- and HCN1+/+ mice were intraperitoneally injected of BrdU and then treated with 5 mg/kg ketamine (KET group, n=5) or same volume of normal saline (NS group, n= 5) by single intraperitoneal injection. Each group was euthanized for immunohistochemical processing of 5-Bromo-2-deoxyuridine (BrdU)-labeled cells in hippocampus at 24 h after the intraperitoneal injection of saline or ketamine. The immobility time in FST of HCN1-/- mice was less than the HCN1+/+ mice before administration of CORT. It shows that the depressive state of HCN1-/- mice is less intensive than that of HCN1+/+ mice. And the immoblility time in both HCN1-/- and HCN1+/+ mice was increased after oral administration of low dose corticosterone, with an increase in depression. In addition, the comparisons were also made to the reduction of immobility time within 30 min, 24 h and 7 d. At any time point, the reduction of immobility time in HCN1+/+ KET group was higher than those in the other three groups (P<0. 05). Furthermore, there were no statistical significances among the three groups including HCN1-/- KET group, HCN1+/+ NS group, HCN1-/- NS group at any point. The number of

  9. De novo mutations in HCN1 cause early infantile epileptic encephalopathy.

    PubMed

    Nava, Caroline; Dalle, Carine; Rastetter, Agnès; Striano, Pasquale; de Kovel, Carolien G F; Nabbout, Rima; Cancès, Claude; Ville, Dorothée; Brilstra, Eva H; Gobbi, Giuseppe; Raffo, Emmanuel; Bouteiller, Delphine; Marie, Yannick; Trouillard, Oriane; Robbiano, Angela; Keren, Boris; Agher, Dahbia; Roze, Emmanuel; Lesage, Suzanne; Nicolas, Aude; Brice, Alexis; Baulac, Michel; Vogt, Cornelia; El Hajj, Nady; Schneider, Eberhard; Suls, Arvid; Weckhuysen, Sarah; Gormley, Padhraig; Lehesjoki, Anna-Elina; De Jonghe, Peter; Helbig, Ingo; Baulac, Stéphanie; Zara, Federico; Koeleman, Bobby P C; Haaf, Thomas; LeGuern, Eric; Depienne, Christel

    2014-06-01

    Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels contribute to cationic Ih current in neurons and regulate the excitability of neuronal networks. Studies in rat models have shown that the Hcn1 gene has a key role in epilepsy, but clinical evidence implicating HCN1 mutations in human epilepsy is lacking. We carried out exome sequencing for parent-offspring trios with fever-sensitive, intractable epileptic encephalopathy, leading to the discovery of two de novo missense HCN1 mutations. Screening of follow-up cohorts comprising 157 cases in total identified 4 additional amino acid substitutions. Patch-clamp recordings of Ih currents in cells expressing wild-type or mutant human HCN1 channels showed that the mutations had striking but divergent effects on homomeric channels. Individuals with mutations had clinical features resembling those of Dravet syndrome with progression toward atypical absences, intellectual disability and autistic traits. These findings provide clear evidence that de novo HCN1 point mutations cause a recognizable early-onset epileptic encephalopathy in humans.

  10. Detection of CO and HCN in Pluto's atmosphere with ALMA

    NASA Astrophysics Data System (ADS)

    Lellouch, E.; Gurwell, M.; Butler, B.; Fouchet, T.; Lavvas, P.; Strobel, D. F.; Sicardy, B.; Moullet, A.; Moreno, R.; Bockelée-Morvan, D.; Biver, N.; Young, L.; Lis, D.; Stansberry, J.; Stern, A.; Weaver, H.; Young, E.; Zhu, X.; Boissier, J.

    2017-04-01

    Observations of the Pluto-Charon system, acquired with the ALMA interferometer on June 12-13, 2015, have led to the detection of the CO(3-2) and HCN(4-3) rotational transitions from Pluto (including the hyperfine structure of HCN), providing a strong confirmation of the presence of CO, and the first observation of HCN in Pluto's atmosphere. The CO and HCN lines probe Pluto's atmosphere up to ∼450 km and ∼900 km altitude, respectively, with a large contribution due to limb emission. The CO detection yields (i) a much improved determination of the CO mole fraction, as 515 ± 40 ppm for a 12 μbar surface pressure (ii) strong constraints on Pluto's mean atmospheric dayside temperature profile over ∼50-400 km, with clear evidence for a well-marked temperature decrease (i.e., mesosphere) above the 30-50 km stratopause and a best-determined temperature of 70 ± 2 K at 300 km, somewhat lower than previously estimated from stellar occultations (81 ± 6 K), and in agreement with recent inferences from New Horizons / Alice solar occultation data. The HCN line shape implies a high abundance of this species in the upper atmosphere, with a mole fraction >1.5 × 10-5 above 450 km and a value of 4 × 10-5 near 800 km. Assuming HCN at saturation, this would require a warm (>92 K) upper atmosphere layer; while this is not ruled out by the CO emission, it is inconsistent with the Alice-measured CH4 and N2 line-of-sight column densities. Taken together, the large HCN abundance and the cold upper atmosphere imply supersaturation of HCN to a degree (7-8 orders of magnitude) hitherto unseen in planetary atmospheres, probably due to a lack of condensation nuclei above the haze region and the slow kinetics of condensation at the low pressure and temperature conditions of Pluto's upper atmosphere. HCN is also present in the bottom ∼100 km of the atmosphere, with a 10-8-10-7 mole fraction; this implies either HCN saturation or undersaturation there, depending on the precise

  11. Rotational excitation of HCN by para- and ortho-H₂.

    PubMed

    Vera, Mario Hernández; Kalugina, Yulia; Denis-Alpizar, Otoniel; Stoecklin, Thierry; Lique, François

    2014-06-14

    Rotational excitation of the hydrogen cyanide (HCN) molecule by collisions with para-H2(j = 0, 2) and ortho-H2(j = 1) is investigated at low temperatures using a quantum time independent approach. Both molecules are treated as rigid rotors. The scattering calculations are based on a highly correlated ab initio 4-dimensional (4D) potential energy surface recently published. Rotationally inelastic cross sections among the 13 first rotational levels of HCN were obtained using a pure quantum close coupling approach for total energies up to 1200 cm(-1). The corresponding thermal rate coefficients were computed for temperatures ranging from 5 to 100 K. The HCN rate coefficients are strongly dependent on the rotational level of the H2 molecule. In particular, the rate coefficients for collisions with para-H2(j = 0) are significantly lower than those for collisions with ortho-H2(j = 1) and para-H2(j = 2). Propensity rules in favor of even Δj transitions were found for HCN in collisions with para-H2(j = 0) whereas propensity rules in favor of odd Δj transitions were found for HCN in collisions with H2(j ⩾ 1). The new rate coefficients were compared with previously published HCN-para-H2(j = 0) rate coefficients. Significant differences were found due the inclusion of the H2 rotational structure in the scattering calculations. These new rate coefficients will be crucial to improve the estimation of the HCN abundance in the interstellar medium.

  12. The Relationship of HCN, C2H6, & H2O in Comets: A Key Clue to Origins?

    NASA Astrophysics Data System (ADS)

    Mumma, Michael J.; Charnley, Steven B.; Cordiner, Martin; Paganini, Lucas; Villanueva, Geronimo Luis

    2017-10-01

    Background: HCN, C2H6, and H2O are three of the best characterized volatiles in comets. It is often assumed that all three are primary volatiles, native to the nucleus. Here, we compare their properties in 26 comets (9 JFC and 17 Oort-cloud), making 6 points:1. Both HCN and C2H6 are poor proxies for water production. The production rate ratio (Q-ratio) of each trace gas relative to water varies by a factor of six among these comets.2. All 26 comets have Q-ratios HCN/C2H6 > 0.1. In 18 comets the Q-ratios HCN/H2O and C2H6/H2O are correlated, with a mean ratio of 0.33. In 6 comets undergoing complete disruption, this Q-ratio exceeds 0.5.3. Q-ratios HCN/C2H6 are not correlated with Q(H2O), nor are they correlated with dynamical class (Oort cloud vs. JFC).4. The nucleus-centered rotational temperatures measured for H2O and other primary species (C2H6, CH3OH) usually agree within error, but those for HCN are often slightly cooler. Could this mean that HCN is not fully developed in the warm near-nucleus region, and instead is at least in part a product species?5. 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). Is HCN produced in part from an apolar precursor?6. ALMA maps of HCN and the dust continuum show a slight displacement in their centroids. Is this the signature of extended production of HCN?HCN as a product species: Points 4-6 suggest that HCN may have a significant distributed source. The astrochemical species ammonium cyanide is a strong candidate for this HCN precursor; at moderately low temperatures (< 200K) NH4CN is a stable solid, but it dissociates into HCN and NH3 when warmed. Disruption could eject macroscopic solid NH4CN into the coma where subsequent warming and release could augment

  13. Novel insights into the distribution of cardiac HCN channels: an expression study in the mouse heart.

    PubMed

    Herrmann, Stefan; Layh, Beate; Ludwig, Andreas

    2011-12-01

    HCN pacemaker channels (I(f) channels) are believed to contribute to important functions in the heart; thus these channels became an attractive target for generating transgenic mouse mutants to elucidate their role in physiological and pathophysiological cardiac conditions. A full understanding of cardiac I(f) and the interpretation of studies using HCN mouse mutants require detailed information about the expression profile of the individual HCN subunits. Here we investigate the cardiac expression pattern of the HCN isoforms at the mRNA as well as at the protein level. The specificity of antibodies used was strictly confirmed by the use of HCN1, HCN2 and HCN4 knockout animals. We find a low, but highly differential HCN expression profile outside the cardiac conduction pathway including left and right atria and ventricles. Additionally HCN distribution was investigated in tissue slices of the sinoatrial node, the atrioventricular node, the bundle of His and the bundle branches. The conduction system was marked by acetylcholine esterase staining. HCN4 was confirmed as the predominant isoform of the primary pacemaker followed by a distinct expression of HCN1. In contrast HCN2 shows only a confined expression to individual pacemaker cells. Immunolabeling of the AV-node reveals also a pronounced specificity for HCN1 and HCN4. Compared to the SN and AVN we found a low but selective expression of HCN4 as the only isoform in the atrioventricular bundle. However in the bundle branches HCN1, HCN4 and also HCN2 show a prominent and selective expression pattern. Our results display a characteristic distribution of individual HCN isoforms in several cardiac compartments and reveal that beside HCN4, HCN1 represents the isoform which is selectively expressed in most parts of the conduction system suggesting a substantial contribution of HCN1 to pacemaking. 2011 Elsevier Ltd. All rights reserved.

  14. CN and HCN in the infrared spectrum of IRC + 10216

    NASA Technical Reports Server (NTRS)

    Wiedemann, G. R.; Deming, D.; Jennings, D. E.; Hinkle, Kenneth H.; Keady, John J.

    1991-01-01

    The abundance of HCN in the inner circumstellar shell of IRC + 10216 has been remeasured using the 12-micron nu2 band. The 12-micron lines are less saturated than HCN 3-micron lines previously detected in the spectrum of IRC + 10216. The observed 12-micron HCN line is formed in the circumstellar shell from about 4 to 12 R sub * in accord with a photospheric origin for HCN. The derived HCN abundance in the 4 to 12 R sub* region is 4 x 10 exp-5 and the column density is 7 x 10 exp 18/sq cm. The 5-micron CN vibration-rotation fundamental band was detected for the first time in an astronomical source. Using four CN lines, the CN column density was determined to be 2.6 x 10 exp 15/sq cm and the rotational temperature to be 8 +/-2 K. The peal radial abundance is 1 x 10 exp -5. The values for the temperature and abundance are in good agreement with microwave results and with the formation of CN from the photolysis of HCN.

  15. HCN1 Channels Contribute to the Effects of Amnesia and Hypnosis But Not Immobility of Volatile Anesthetics

    PubMed Central

    Liu, Jin; Ke, Bowen; Wang, Xiaojia; Li, Fengshan; Li, Tao; Bayliss, Douglas A.; Chen, Xiangdong

    2015-01-01

    Background HCN1 channels have been identified as targets of ketamine to produce hypnosis. Volatile anesthetics also inhibit HCN1 channels. However, the effects of HCN1 channels on volatile anesthetics in vivo is still elusive. This study uses global and conditional HCN1 knockout mice to evaluate how HCN1 channels affect the actions of volatile anesthetics. Methods Minimum alveolar concentrations (MAC) of isoflurane and sevoflurane that induced immobility (MAC of immobility) and/or hypnosis (MAC of hypnosis) were determined in wild-type (WT) mice, global HCN1 channel knockout mice (HCN1−/−), floxed HCN1 channel gene (HCN1f/f) mice and forebrain-selective HCN1 channel knockout (HCN1f/f: cre) mice. Immobility of mice was defined as no purposeful reactions to tail-clamping stimulus and hypnosis was defined as loss of righting reflex (LORR). The amnestic effects of isoflurane and sevoflurane were evaluated by fear-potentiated startle in these four strains of mice. Results All MAC values were expressed as mean ± SEM. For MAC of immobility of isoflurane, no significant difference was found among wild-type, HCN1−/−, HCN1f/f and HCN1f/f: cre mice (all ~1.24-1.29% isoflurane). For both HCN1−/− and HCN1f/f: cre mice, the MAC of hypnosis for isoflurane (each ~1.05% isoflurane) were significantly increased over their nonknockout controls: HCN1−/− vs. wild-type (0.86±0.03%, P<0.001) and HCN1f/f: cre vs. HCN1f/f mice (0.84±0.03%, P<0.001); no significant difference was found between HCN1−/− and HCN1f/f: cre mice. For MAC of immobility of sevoflurane, no significant difference was found among wild-type, HCN1−/−, HCN1f/f and HCN1f/f: cre mice (all ~2.6-2.7% sevoflurane). For both HCN1−/− and HCN1f/f: cre mice, the MAC of hypnosis for sevoflurane (each ~1.90% sevoflurane) was significantly increased over their nonknockout controls: HCN1−/− vs. wild-type (1.58±0.05%, P<0.001) and HCN1f/f: cre vs. HCN1f/f mice (1.56±0.05%, P<0.001). No significant

  16. HCN(1-0) enhancement in the bar of NGC 2903

    NASA Astrophysics Data System (ADS)

    Leon, S.; Jeyakumar, S.; Pérez-Ramírez, D.; Verdes-Montenegro, L.; Lee, S. W.; Ocaña Flaquer, B.

    2008-12-01

    We have mapped the HCN(1-0) emission from two spiral galaxies, NGC 2903 and NGC 3504 to study the gas properties in the bars. The HCN(1-0) emission is detected in the center and along the bar of NGC 2903. The line ratio HCN(1-0)/ 12CO(1-0) ranges from 0.07 to 0.12 with the lowest value in the center. The enhancement of HCN(1-0) emission along the bar indicates a higher fraction of dense molecular gas in the bar than at the center. The mass of dense molecular gas in the center (2.2 × 107 M⊙) is about 6 times lower than that in the bar (1.2 × 108 M⊙). The total star formation rate (SFR) is estimated to be 1.4 M⊙ yr-1, where the SFR at the center is 1.9 times higher than that in the bar. The time scale of consumption of the dense molecular gas in the center is about ~ 3 × 107 yr which is much shorter than that in the bar of about 2 to 10 × 108 yr. The dynamical time scale of inflow of the gas from the bar to the center is shorter than the consumption time scale in the bar, which suggests that the star formation (SF) activity at the center is not deprived of fuel. In the bar, the fraction of dense molecular gas mass relative to the total molecular gas mass is twice as high along the leading edge than along the central axis of the bar. The HCN(1-0) emission has a large velocity dispersion in the bar, which can be attributed partially to the streaming motions indicative of shocks along the bar. In NGC 3504, the HCN(1-0) emission is detected only at the center. The fraction of dense molecular gas mass in the center is about 15%. Comparison of the SFR with the predictions from numerical simulations suggest that NGC 2903 harbors a young type B bar with a strong inflow of gas toward the center whereas NGC 3504 has an older bar and has already passed the phase of inflow of gas toward the center.

  17. Electric discharge synthesis of HCN in simulated Jovian atmospheres

    NASA Technical Reports Server (NTRS)

    Stribling, Roscoe; Miller, Stanley L.

    1987-01-01

    Corona discharge is presently considered as a possible source of the HCN detected in the Jovian atmosphere at 2.2 x 10 to the -7th moles/sq cm column density, for the cases of gas mixtures containing H2, CH4, and NH3, with H2/CH4 ratios from 4.4 to 1585. A 3:1 ratio of corona discharge to lightning energy similar to that of the earth is applied to Jupiter. Depending on the lightning energy available on Jupiter and the eddy diffusion coefficients in the synthesis region, HCN column densities generated by corona discharge could account for about 10 percent of the HCN observed.

  18. HCN production from impact ejecta on the early Earth

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    Major impact events have drastically altered the evolution of life on Earth. The reentry of ejecta formed from these events can trigger widespread chemical changes to the atmosphere on a global scale. This mechanism was proposed as a source of HCN during the Late Heavy Bombardment (LHB), 4.1 to 3.8 billion years ago. Significant concentrations of HCN in surface water could directly lead to adenine formation, a precursor for RNA. This work uses the Direct Simulation Monte Carlo (DSMC) method to examine the production of CN and HCN due to the reentry of impact ejecta. We use the Statistical Modeling in Low-Density Environment (SMILE) code, which utilizes the Total Collisional Energy (TCE) model for reactions. The collisions are described by the Variable Soft Sphere (VSS) and Larsen-Borgnakke (LB) models. We compare this nonequilibrium production to equilibrium concentrations from bulk atmospheric heating. The equilibrium HCN yield for a 1023 J impact is 7.0×104 moles, corresponding to a 2.5×1014 molecules per m2 surface deposition. We find that additional CN and HCN is produced under thermochemical nonequilibrium, particularly at higher altitudes. The total nonequilibrium yield for a 1023 J impact is 1.2×106 moles of HCN, a value 17 times the equilibrium result. This corresponds to a surface deposition of 1.4×1015 molecules per m2. This increase in production indicates that thermochemical nonequilibrium effects play a strong role in HCN from impact ejecta, and must be considered when investigating impacts as a plausible mechanism for significant adenine production during the LHB.

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

    PubMed Central

    D’Souza, Alicia; Pearman, Charles M.; Wang, Yanwen; Nakao, Shu; Logantha, Sunil Jit R.J.; Cox, Charlotte; Bennett, Hayley; Zhang, Yu; Johnsen, Anne Berit; Linscheid, Nora; Poulsen, Pi Camilla; Elliott, Jonathan; Coulson, Jessica; McPhee, Jamie; Robertson, Abigail; da Costa Martins, Paula A.; Kitmitto, Ashraf; Wisløff, Ulrik; Cartwright, Elizabeth J.; Monfredi, Oliver; Lundby, Alicia; Dobrzynski, Halina; Oceandy, Delvac; Morris, Gwilym M.

    2017-01-01

    Rationale: Downregulation of the pacemaking ion channel, HCN4 (hyperpolarization-activated cyclic nucleotide gated channel 4), and the corresponding ionic current, If, underlies exercise training–induced sinus bradycardia in rodents. If this occurs in humans, it could explain the increased incidence of bradyarrhythmias in veteran athletes, and it will be important to understand the underlying processes. Objective: To test the role of HCN4 in the training-induced bradycardia in human athletes and investigate the role of microRNAs (miRs) in the repression of HCN4. Methods and Results: As in rodents, the intrinsic heart rate was significantly lower in human athletes than in nonathletes, and in all subjects, the rate-lowering effect of the HCN selective blocker, ivabradine, was significantly correlated with the intrinsic heart rate, consistent with HCN repression in athletes. Next-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 in HCN4 3′-untranslated region luciferase reporter activity on cotransfection with precursor miR-423-5p (abolished by mutation of predicted recognition elements). Knockdown of miR-423-5p with anti-miR-423-5p reversed training-induced bradycardia via rescue of HCN4 and If. Further experiments showed that in the sinus node of swim-trained mice, upregulation of miR-423-5p (intronic miR) and its host gene, NSRP1, is driven by an upregulation of the transcription factor Nkx2.5. Conclusions: HCN remodeling likely occurs in human athletes, as well as in rodent models. miR-423-5p contributes to training-induced bradycardia by targeting HCN4. This work presents the first evidence of miR control of HCN4 and heart rate. miR-423-5p could be a therapeutic target for pathological sinus node

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

    PubMed

    D'Souza, Alicia; Pearman, Charles M; Wang, Yanwen; Nakao, Shu; Logantha, Sunil Jit R J; Cox, Charlotte; Bennett, Hayley; Zhang, Yu; Johnsen, Anne Berit; Linscheid, Nora; Poulsen, Pi Camilla; Elliott, Jonathan; Coulson, Jessica; McPhee, Jamie; Robertson, Abigail; da Costa Martins, Paula A; Kitmitto, Ashraf; Wisløff, Ulrik; Cartwright, Elizabeth J; Monfredi, Oliver; Lundby, Alicia; Dobrzynski, Halina; Oceandy, Delvac; Morris, Gwilym M; Boyett, Mark R

    2017-10-13

    Downregulation of the pacemaking ion channel, HCN4 (hyperpolarization-activated cyclic nucleotide gated channel 4), and the corresponding ionic current, I f , underlies exercise training-induced sinus bradycardia in rodents. If this occurs in humans, it could explain the increased incidence of bradyarrhythmias in veteran athletes, and it will be important to understand the underlying processes. To test the role of HCN4 in the training-induced bradycardia in human athletes and investigate the role of microRNAs (miRs) in the repression of HCN4. As in rodents, the intrinsic heart rate was significantly lower in human athletes than in nonathletes, and in all subjects, the rate-lowering effect of the HCN selective blocker, ivabradine, was significantly correlated with the intrinsic heart rate, consistent with HCN repression in athletes. Next-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 in HCN4 3'-untranslated region luciferase reporter activity on cotransfection with precursor miR-423-5p (abolished by mutation of predicted recognition elements). Knockdown of miR-423-5p with anti-miR-423-5p reversed training-induced bradycardia via rescue of HCN4 and I f . Further experiments showed that in the sinus node of swim-trained mice, upregulation of miR-423-5p (intronic miR) and its host gene, NSRP1, is driven by an upregulation of the transcription factor Nkx2.5. HCN remodeling likely occurs in human athletes, as well as in rodent models. miR-423-5p contributes to training-induced bradycardia by targeting HCN4. This work presents the first evidence of miR control of HCN4 and heart rate. miR-423-5p could be a therapeutic target for pathological sinus node dysfunction in veteran athletes. © 2017 The Authors.

  1. Augmented Currents of an HCN2 Variant in Patients with Febrile Seizure Syndromes

    PubMed Central

    Dibbens, Leanne M.; Reid, Christopher A.; Hodgson, Bree; Thomas, Evan A.; Phillips, Alison M.; Gazina, Elena; Cromer, Brett A.; Clarke, Alison L.; Baram, Tallie Z.; Scheffer, Ingrid E.; Berkovic, Samuel F.; Petrou, Steven

    2012-01-01

    The genetic architecture of common epilepsies is largely unknown. HCNs are excellent epilepsy candidate genes because of their fundamental neurophysiological roles. Screening in subjects with febrile seizures and genetic epilepsy with febrile seizures plus revealed that 2.4% carried a common triple proline deletion (delPPP) in HCN2 that was seen in only 0.2% of blood bank controls. Currents generated by mutant HCN2 channels were ~35% larger than those of controls; an effect revealed using automated electrophysiology and an appropriately powered sample size. This is the first association of HCN2 and familial epilepsy, demonstrating gain of function of HCN2 current as a potential contributor to polygenic epilepsy. PMID:20437590

  2. Down-regulation of T-type Cav3.2 channels by hyperpolarization-activated cyclic nucleotide-gated channel 1 (HCN1): Evidence of a signaling complex

    PubMed Central

    Fan, Jing; Gandini, Maria A.; Zhang, Fang-Xiong; Chen, Lina; Souza, Ivana A.; Zamponi, Gerald W.

    2017-01-01

    ABSTRACT Formation of complexes between ion channels is important for signal processing in the brain. Here we investigate the biochemical and biophysical interactions between HCN1 channels and Cav3.2 T-type channels. We found that HCN1 co-immunoprecipitated with Cav3.2 from lysates of either mouse brain or tsA-201 cells, with the HCN1 N-terminus associating with the Cav3.2 N-terminus. Cav3.2 channel activity appeared to be functionally regulated by HCN1. The expression of HCN1 induced a decrease in Cav3.2 Ba2+ influx (IBa2+) along with altered channel kinetics and a depolarizing shift in activation gating. However, a reciprocal regulation of HCN1 by Cav3.2 was not observed. This study highlights a regulatory role of HCN1 on Cav3.2 voltage-dependent properties, which are expected to affect physiologic functions such as synaptic transmission and cellular excitability. PMID:28467171

  3. Relevance of HCN2-expressing human mesenchymal stem cells for the generation of biological pacemakers.

    PubMed

    Bruzauskaite, Ieva; Bironaite, Daiva; Bagdonas, Edvardas; Skeberdis, Vytenis Arvydas; Denkovskij, Jaroslav; Tamulevicius, Tomas; Uvarovas, Valentinas; Bernotiene, Eiva

    2016-04-30

    The transfection of human mesenchymal stem cells (hMSCs) with the hyperpolarization-activated cyclic nucleotide-gated ion channel 2 (HCN2) gene has been demonstrated to provide biological pacing in dogs with complete heart block. The mechanism appears to be the generation of the ion current (If) by the HCN2-expressing hMSCs. However, it is not clear how the transfection process and/or the HCN2 gene affect the growth functions of the hMSCs. Therefore, we investigated survival, proliferation, cell cycle, and growth on a Kapton® scaffold of HCN2-expressing hMSCs. hMSCs were isolated from the bone marrow of healthy volunteers applying a selective cell adhesion procedure and were identified by their expression of specific surface markers. Cells from passages 2-3 were transfected by electroporation using commercial transfection kits and a pIRES2-EGFP vector carrying the pacemaker gene, mouse HCN2 (mHCN2). Transfection efficiency was confirmed by enhanced green fluorescent protein (EGFP) fluorescence, quantitative real-time polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA). After hMSCs were transfected, their viability, proliferation, If generation, apoptosis, cell cycle, and expression of transcription factors were measured and compared with non-transfected cells and cells transfected with pIRES2-EGFP vector alone. Intracellular mHCN2 expression after transfection increased from 22.14 to 62.66 ng/mg protein (p < 0.05). Transfection efficiency was 45 ± 5 %. The viability of mHCN2-transfected cells was 82 ± 5 %; they grew stably for more than 3 weeks and induced If current. mHCN2-transfected cells had low mitotic activity (10.4 ± 1.24 % in G2/M and 83.6 ± 2.5 % in G1 phases) as compared with non-transfected cells (52-53 % in G2/M and 31-35 % in G1 phases). Transfected cells showed increased activation of nine cell cycle-regulating transcription factors: the most prominent upregulation was of AMP-dependent transcription factor ATF3 (7

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

    NASA Astrophysics Data System (ADS)

    Aguado, Alfredo; Roncero, Octavio; Zanchet, Alexandre; Agúndez, Marcelino; Cernicharo, José

    2017-03-01

    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.

  5. Synthesis of HCN and HNC in Ion-Irradiated N2-Rich Ices

    NASA Technical Reports Server (NTRS)

    Moore, M. H.; Hudson, R. L.; Ferrante, R. F.

    2002-01-01

    Near-IR observations reveal that N2-rich ice containing small amounts of CH4, and CO, is abundant on the surfaces of Triton, a moon of Neptune, and Pluto. N2-rich ices may also exist, in interstellar environments. To investigate the radiation chemistry of such ices we performed a systematic IR study of ion-irradiated Nz-rich mixtures containing CH4 and CO. Irradiation of N2 + CH4 mixtures at 12 K, showed that HCN, HNC, diazomethane, and NH3 were produced. We also found that UV photolysis of these ices produced detectable HCN and HNC. Intrinsic band strengths, A(HCN) and A(HNC), were measured and used to calculate yields of HCN and HNC. Similar results were obtained on irradiation of N2 + CH4 + CO ices at 12 K, with the main difference being the formation of HNCO. In all cases we observed changes on warming. For example, when the temperature of irradiated Nz + CH4 + CO was raised from 12 to 30 K, HCN, HNC, and HNCO reacted with NH3, and OCN-, CN-, N3-, and NH4+ were produced. These ions, appearing at 30 K, are expected to form and survive on the surfaces of Triton, Pluto, and interstellar grains. Our results have astrobiological implications since some of these radiation products are involved in the syntheses of biomolecules such as amino acids and peptides.

  6. HCN1 Channels as Targets for Anesthetic and Nonanesthetic Propofol Analogs in the Amelioration of Mechanical and Thermal Hyperalgesia in a Mouse Model of Neuropathic Pain

    PubMed Central

    Tibbs, Gareth R.; Rowley, Thomas J.; Sanford, R. Lea; Herold, Karl F.; Proekt, Alex; Hemmings, Hugh C.; Andersen, Olaf S.; Flood, Pamela D.

    2013-01-01

    Chronic pain after peripheral nerve injury is associated with afferent hyperexcitability and upregulation of hyperpolarization-activated, cyclic nucleotide-regulated (HCN)–mediated IH pacemaker currents in sensory neurons. HCN channels thus constitute an attractive target for treating chronic pain. HCN channels are ubiquitously expressed; analgesics targeting HCN1-rich cells in the peripheral nervous system must spare the cardiac pacemaker current (carried mostly by HCN2 and HCN4) and the central nervous system (where all four isoforms are expressed). The alkylphenol general anesthetic propofol (2,6-di-iso-propylphenol) selectively inhibits HCN1 channels versus HCN2HCN4 and exhibits a modest pharmacokinetic preference for the periphery. Consequently, we hypothesized that propofol, and congeners, should be antihyperalgesic. Alkyl-substituted propofol analogs have different rank-order potencies with respect to HCN1 inhibition, GABAA receptor (GABAA-R) potentiation, and general anesthesia. Thus, 2,6- and 2,4-di-tertbutylphenol (2,6- and 2,4-DTBP, respectively) are more potent HCN1 antagonists than propofol, whereas 2,6- and 2,4-di-sec-butylphenol (2,6- and 2,4-DSBP, respectively) are less potent. In contrast, DSBPs, but not DTBPs, enhance GABAA-R function and are general anesthetics. 2,6-DTBP retained propofol’s selectivity for HCN1 over HCN2HCN4. In a peripheral nerve ligation model of neuropathic pain, 2,6-DTBP and subhypnotic propofol are antihyperalgesic. The findings are consistent with these alkylphenols exerting analgesia via non-GABAA-R targets and suggest that antagonism of central HCN1 channels may be of limited importance to general anesthesia. Alkylphenols are hydrophobic, and thus potential modifiers of lipid bilayers, but their effects on HCN channels are due to direct drug-channel interactions because they have little bilayer-modifying effect at therapeutic concentrations. The alkylphenol antihyperalgesic target may be HCN1 channels in the

  7. Functional Characterization of Cnidarian HCN Channels Points to an Early Evolution of Ih.

    PubMed

    Baker, Emma C; Layden, Michael J; van Rossum, Damian B; Kamel, Bishoy; Medina, Monica; Simpson, Eboni; Jegla, Timothy

    2015-01-01

    HCN channels play a unique role in bilaterian physiology as the only hyperpolarization-gated cation channels. Their voltage-gating is regulated by cyclic nucleotides and phosphatidylinositol 4,5-bisphosphate (PIP2). Activation of HCN channels provides the depolarizing current in response to hyperpolarization that is critical for intrinsic rhythmicity in neurons and the sinoatrial node. Additionally, HCN channels regulate dendritic excitability in a wide variety of neurons. Little is known about the early functional evolution of HCN channels, but the presence of HCN sequences in basal metazoan phyla and choanoflagellates, a protozoan sister group to the metazoans, indicate that the gene family predates metazoan emergence. We functionally characterized two HCN channel orthologs from Nematostella vectensis (Cnidaria, Anthozoa) to determine which properties of HCN channels were established prior to the emergence of bilaterians. We find Nematostella HCN channels share all the major functional features of bilaterian HCNs, including reversed voltage-dependence, activation by cAMP and PIP2, and block by extracellular Cs+. Thus bilaterian-like HCN channels were already present in the common parahoxozoan ancestor of bilaterians and cnidarians, at a time when the functional diversity of voltage-gated K+ channels was rapidly expanding. NvHCN1 and NvHCN2 are expressed broadly in planulae and in both the endoderm and ectoderm of juvenile polyps.

  8. The HNC/HCN ratio in comets

    NASA Technical Reports Server (NTRS)

    Irvine, W. M.; Dickens, J. E.; Lovell, A. J.; Schloerb, F. P.; Senay, M.; Bergin, E. A.; Jewitt, D.; Matthews, H. E.; Ferris, J. P. (Principal Investigator)

    1997-01-01

    The abundance ratio of the isomers HCN and HNC has been investigated in comet Hale-Bopp (C/1995 O1) through observations of the J = 4-3 rotational transitions of both species for heliocentric distances 0.93 < r < 3 AU, both pre- and post-perihelion. After correcting for the optical depth of the stronger HCN line, we find that the column density ratio of HNC/HCN in our telescope beam increases significantly as the comet approaches the Sun. We compare this behavior to that predicted from an ion-molecule chemical model and conclude that the HNC is produced in significant measure by chemical processes in the coma; i.e., for comet Hale-Bopp, HNC is not a parent molecule sublimating from the nucleus.

  9. 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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Imanishi, Masatoshi; Nakanishi, Kouichiro; Izumi, Takuma, E-mail: masa.imanishi@nao.ac.jp

    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 simultaneouslymore » 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.« less

  10. Chemical Recycling of HCN in Cometary Comae

    NASA Astrophysics Data System (ADS)

    Boice, Daniel C.; Kawakita, Hideyo; Shinnaka, Yoshiharu; Mumma, Michael J.; Kobayashi, Hitomi; Ogawa, Sayuri

    2014-11-01

    Modeling is essential to understand the important physical and chemical processes that occur in cometary comae, especially the relationship between putative parent and daughter molecules, such as, HCN and CN. Photochemistry is a major source of ions and electrons that further initiate key gas-phase reactions, contributing to the plethora of molecules and atoms observed in comets. The effects of photoelectrons that interact via impacts are important to the overall excitation and dissociation processes in the inner coma. We consider the relevant processes in the collision-dominated, inner coma of a comet within a global modeling framework to understand observations of HCN and CN. The CN source(s) must be able to produce highly collimated jets, be consistent with the observed CN parent scale length, and have a production rate consistent with the observed CN production. HCN fulfills these conditions in some comets (e.g., 1P/Halley, Hale-Bopp) while it does not in others (e.g., 8P/Tuttle, 6P/d’Arrest, 73P/S-W3, 2P/Encke, 9P/Temple 1 and C/2007 W1).We investigate the chemistry of HCN with our chemical kinetics coma model including a network with other possible CN parents, as well as a dust component that may be a potential source of CN. It is seen that the major destruction pathways of HCN are via photo dissociation (into H and CN) and protonation with water group ions - primarily H3O+. We point out the intriguing “recycling” of HCN via protonation reactions with H3O+, H2O+, OH+, and subsequent dissociative recombination. It seems that HCN molecules observed in the coma can consist of those initially released from the nucleus and those that are freshly formed at different locations in the coma via these protonation/dissociation reactions. We will investigate implications for reconciling discrepancies between observations of HCN and CN in cometary comae.Acknowledgements: We appreciate support from the NSF Planetary Astronomy Program. This program is partially

  11. Alma Observations of HCN and its Isotopologues on Titan

    NASA Technical Reports Server (NTRS)

    Molter, Edward M.; Nixon, C. A.; Cordiner, M. A.; Serigano, J.; Irwin, P. G. J.; Teanby, N. A.; Charnley, S. B.; Lindberg, J. E.

    2016-01-01

    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, H13C15N, and confirm an earlier report of detection of DCN. We model high signal-to-noise observations of HCN, H13CN, HC15N, DCN, and H13C15N to derive abundances and infer the following isotopic ratios: 12C/13C = 89.8 +/- 2.8, 14N/15N = 72.3 +/- 2.2, D/H = (2.5 +/- 0.2) × 10-4, and HCN/H13C15N = 5800 +/- 270 (1sigma errors). The carbon and nitrogen ratios are consistent with and improve on the precision of previous results, confirming a factor of approximately 2.3 elevation in 14N/15N in HCN compared to N2 and a lack of fractionation in 12C/13C 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 approximately 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.

  12. On the HCN and CO 2 abundance and distribution in Jupiter's stratosphere

    NASA Astrophysics Data System (ADS)

    Lellouch, E.; Bézard, B.; Strobel, D. F.; Bjoraker, G. L.; Flasar, F. M.; Romani, P. N.

    2006-10-01

    Observations of Jupiter by Cassini/CIRS, acquired during the December 2000 flyby, provide the latitudinal distribution of HCN and CO 2 in Jupiter's stratosphere with unprecedented spatial resolution and coverage. Following up on a preliminary study by Kunde et al. [Kunde, V.G., and 41 colleagues, 2004. Science 305, 1582-1587], the analysis of these observations leads to two unexpected results (i) the total HCN mass in Jupiter's stratosphere in 2000 was (6.0±1.5)×10 g, i.e., at least three times larger than measured immediately after the Shoemaker-Levy 9 (SL9) impacts in July 1994 and (ii) the latitudinal distributions of HCN and CO 2 are strikingly different: while HCN exhibits a maximum at 45° S and a sharp decrease towards high Southern latitudes, the CO 2 column densities peak over the South Pole. The total CO 2 mass is (2.9±1.2)×10 g. A possible cause for the HCN mass increase is its production from the photolysis of NH 3, although a problem remains because, while millimeter-wave observations clearly indicate that HCN is currently restricted to submillibar ( ˜0.3 mbar) levels, immediate post-impact infrared observations have suggested that most of the ammonia was present in the lower stratosphere near 20 mbar. HCN appears to be a good atmospheric tracer, with negligible chemical losses. Based on 1-dimensional (latitude) transport models, the HCN distribution is best interpreted as resulting from the combination of a sharp decrease (over an order of magnitude in K) of wave-induced eddy mixing poleward of 40° and an equatorward transport with ˜7 cms velocity. The CO 2 distribution was investigated by coupling the transport model with an elementary chemical model, in which CO 2 is produced from the conversion of water originating either from SL9 or from auroral input. The auroral source does not appear adequate to reproduce the CO 2 peak over the South Pole, as required fluxes are unrealistically high and the shape of the CO 2 bulge is not properly matched

  13. Structural studies on HCN oligomers. [catalysts for prebiotic processes

    NASA Technical Reports Server (NTRS)

    Ferris, J. P.; Edelson, E. H.; Auyeung, J. M.; Joshi, P. C.

    1981-01-01

    NMR spectral studies on the HCN oligomers suggest the presence of carboxamide and urea groupings. The release of CO2, H2O, HCN, CH3CN, HCONH2 and pyridine on pyrolysis is consistent with the presence of these groupings as well as carboxylic acid groups. No basic primary amine groupings could be detected with fluorescamine. Hydrazinolysis of the HCN oligomers releases 10% of the amino acids normally released by acid hydrolysis. The oligomers give a positive biuret test but this is not due to the presence of peptide bonds. There is no conclusive evidence for the presence of peptide bonds in the HCN oligomers. No diglycine was detected on partial hydrolysis of the HCN oligomers at pH 8.5 suggesting that HCN oligomers were not a source of prebiotic peptides.

  14. The vertical distribution and origin of HCN in Neptune's atmosphere

    NASA Technical Reports Server (NTRS)

    Lellouch, Emmanuel; Romani, Paul N.; Rosenqvist, Jan

    1994-01-01

    Measurements and modeling of the (3-2) rotational line of hydrogen cyanide at 265.9 GHz in Neptune's atmosphere are presented. High signal-to-noise observations provide information on the HCN vertical distribution in Neptune's stratosphere. The HCN mixing ratio is found to be nearly uniform with height above the condensation level. Best fits occur for HCN distributions that have a slight increase with altitude. A least-squares analysis yields a mixing ratio of (3.2 +/- 0.8)10(exp -10) at 2 mbar and a mean mixing ratio scale height of 250(sup 750)(sub -110) km in the 0.1-3 mbar region. To interpret these results, we developed a photochemical model of HCN. HCN formation is initiated by the reaction between CH3 radicals, produced from methane photochemistry, and N atoms. The primary sink for HCN is condensation, with minor contributions from photolysis and chemical losses. Two possible sources of N atoms are investigated: (1) infall of N escaped from Triton's upper atmosphere, and (2) galactic cosmic ray (GCR) impact on internal N2. Given the uncertainties on (i) the transport and possible ionization of N in Neptune's magnetosphere, and the fate of N(+) reaching Neptune's upper atmosphere and (ii) the N2 mixing ratio in Neptune's deep atmosphere, we suggest that both sources of N atoms may significantly contibute to the formation of HCN.

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

    PubMed

    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.

  16. HCN Channels Modulators: The Need for Selectivity

    PubMed Central

    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

  17. Biomolecules from HCN

    NASA Technical Reports Server (NTRS)

    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.

  18. HCN4 mutation as a molecular explanation on patients with bradycardia and non-compaction cardiomyopathy.

    PubMed

    Millat, Gilles; Janin, Alexandre; de Tauriac, Olivier; Roux, Antoine; Dauphin, Claire

    2015-09-01

    A very recent study suggested that HCN4 mutations could be associated with sinusal bradycardia and myocardial non compaction. A French family with 3 affected sisters presenting the same clinical phenotype (sinus bradycardia in combination with non compaction cardiomyopathy (NCCM)) have benefited both from a systematic cardiovascular exploration and molecular investigations. The molecular analysis, performed by NGS sequencing, led to identify only one likely-disease causing variation: p.Gly482Arg on HCN4 gene. Our results confirm the genetic evidence for the involvement of the HCN4 mutations in the combined bradycardia-NCCM phenotype and illustrates that, in front of this combined clinical phenotype, HCN4 mutations has to be suspected. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mills, Elisabeth A. C.; Battersby, Cara, E-mail: elisabeth.mills@sjsu.edu

    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 ofmore » 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.« less

  20. Near Infrared Spectra of H2O/HCN Mixtures

    NASA Technical Reports Server (NTRS)

    Mastrapa, R. M.; Bernstein, M. P.; Sanford, S. A.

    2006-01-01

    Cassini's VIMS has already returned exciting results interpreting spectra of Saturn's icy satellites. The discovery of unidentified features possibly due to CN compounds inspired the work reported here. We wanted to test HCN as a possibility for explaining these features, and also explore how the features of HCN change when mixed with H2O. We have previously noted that mixing H20 and CO2 produces new spectral features and that those features change with temperature and mixing ratio.

  1. ALMA OBSERVATIONS OF HCN AND ITS ISOTOPOLOGUES ON TITAN

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Molter, Edward M.; Nixon, C. A.; Cordiner, M. A.

    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 themore » 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.« less

  2. Sick sinus syndrome with HCN4 mutations shows early onset and frequent association with atrial fibrillation and left ventricular noncompaction.

    PubMed

    Ishikawa, Taisuke; Ohno, Seiko; Murakami, Takashi; Yoshida, Kentaro; Mishima, Hiroyuki; Fukuoka, Tetsuya; Kimoto, Hiroki; Sakamoto, Risa; Ohkusa, Takafumi; Aiba, Takeshi; Nogami, Akihiko; Sumitomo, Naokata; Shimizu, Wataru; Yoshiura, Koh-Ichiro; Horigome, Hitoshi; Horie, Minoru; Makita, Naomasa

    2017-05-01

    Familial sick sinus syndrome (SSS) is often attributable to mutations in genes encoding the cardiac Na channel SCN5A and pacemaker channel HCN4. We previously found that SSS with SCN5A mutations shows early onset of manifestations and male predominance. Despite recent reports on the complications of atrial fibrillation (AF) and left ventricular noncompaction (LVNC) in patients with SSS caused by HCN4 mutations, their overall clinical spectrum remains unknown. The purpose of this study was to investigate the clinical and demographic features of SSS patients carrying HCN4 mutations. We genetically screened 38 unrelated SSS families and functionally analyzed the mutant SCN5A and HCN4 channels by patch clamping. We also evaluated the clinical features of familial SSS by a meta-analysis of 48 SSS probands with mutations in HCN4 (n = 16) and SCN5A (n = 32), including previously reported cases, and 538 sporadic SSS cases. We identified two HCN4 and three SCN5A loss-of-function mutations in our familial SSS cohort. Meta-analysis of HCN4 mutation carriers showed a significantly younger age at diagnosis (39.1 ± 21.7 years) than in sporadic SSS (74.3 ± 0.4 years; P <.001), but a significantly older age than in SCN5A mutation carriers (20.0 ± 17.6 years; P = .003). Moreover, HCN4 mutation carriers were more frequently associated with AF (43.8%) and LVNC (50%) and with older age at pacemaker implantation (43.5 ± 22.1 years) than were SCN5A mutation carriers (17.8 ± 16.5 years; P <.001). SSS with HCN4 mutations may form a distinct SSS subgroup characterized by early clinical manifestation after adolescence and frequent association with AF and LVNC. Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  3. Disturbed Processing of Contextual Information in HCN3 Channel Deficient Mice

    PubMed Central

    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

  4. The rotational excitation of the HCN and HNC molecules by H2 revisited

    NASA Astrophysics Data System (ADS)

    Hernández Vera, M.; Lique, F.; Dumouchel, F.; Hily-Blant, P.; Faure, A.

    2017-06-01

    HCN and HNC are two fundamental molecules in the dense interstellar medium. The HNC/HCN abundance ratio depends on the kinetic temperature and can be used to explore the physical and chemical conditions of star-forming regions. Modelling of HCN and HNC emissions from interstellar clouds requires to model their collisional and radiative excitations. We report the calculation of the HCN and HNC excitation rate coefficients among the first 26 rotational levels due to H2 collisions, for temperatures ranging from 5 to 500 K, using the exact close coupling and the approximate coupled states methods. We found a propensity for even Δj transitions in the case of HCN-para-H2 collisions, whereas a propensity for odd Δj transitions is observed in the case of HNC-para-H2 collisions. For collisions with ortho-H2, both molecules show a propensity rule favouring transitions with odd Δj. The rate coefficients for HCN and HNC differ significantly, showing clearly that the collisional excitation of the two isomers is different, especially for para-H2. We also evaluate the impact of these new data on the astrophysical modelling through radiative transfer calculations. It is shown that specific calculations have to be performed for the two isomers and that the HNC/HCN abundance ratio in cold molecular clouds cannot be estimated from line intensity ratio. Finally, observations of the two isotopologues H13CN and HN13C towards a sample of prestellar cores are presented, and the larger excitation temperature of HN13C is well reproduced by our excitation model.

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

    NASA Technical Reports Server (NTRS)

    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.

  6. Prefrontal Cortex HCN1 Channels Enable Intrinsic Persistent Neural Firing and Executive Memory Function

    PubMed Central

    Thuault, Sébastien J.; Malleret, Gaël; Constantinople, Christine M.; Nicholls, Russell; Chen, Irene; Zhu, Judy; Panteleyev, Andrey; Vronskaya, Svetlana; Nolan, Matthew F.; Bruno, Randy

    2013-01-01

    In many cortical neurons, HCN1 channels are the major contributors to Ih, the hyperpolarization-activated current, which regulates the intrinsic properties of neurons and shapes their integration of synaptic inputs, paces rhythmic activity, and regulates synaptic plasticity. Here, we examine the physiological role of Ih in deep layer pyramidal neurons in mouse prefrontal cortex (PFC), focusing on persistent activity, a form of sustained firing thought to be important for the behavioral function of the PFC during working memory tasks. We find that HCN1 contributes to the intrinsic persistent firing that is induced by a brief depolarizing current stimulus in the presence of muscarinic agonists. Deletion of HCN1 or acute pharmacological blockade of Ih decreases the fraction of neurons capable of generating persistent firing. The reduction in persistent firing is caused by the membrane hyperpolarization that results from the deletion of HCN1 or Ih blockade, rather than a specific role of the hyperpolarization-activated current in generating persistent activity. In vivo recordings show that deletion of HCN1 has no effect on up states, periods of enhanced synaptic network activity. Parallel behavioral studies demonstrate that HCN1 contributes to the PFC-dependent resolution of proactive interference during working memory. These results thus provide genetic evidence demonstrating the importance of HCN1 to intrinsic persistent firing and the behavioral output of the PFC. The causal role of intrinsic persistent firing in PFC-mediated behavior remains an open question. PMID:23966682

  7. HCN Survey of Normal Spiral, Infrared-luminous, and Ultraluminous Galaxies

    NASA Astrophysics Data System (ADS)

    Gao, Yu; Solomon, Philip M.

    2004-05-01

    We report systematic HCN J=1-0 (and CO) observations of a sample of 53 infrared (IR) and/or CO-bright and/or luminous galaxies, including seven ultraluminous infrared galaxies, nearly 20 luminous infrared galaxies, and more than a dozen of the nearest normal spiral galaxies. This is the largest and most sensitive HCN survey of galaxies to date. All galaxies observed so far follow the tight correlation between the IR luminosity LIR and the HCN luminosity LHCN initially proposed by Solomon, Downes, & Radford, which is detailed in a companion paper. We also address here the issue of HCN excitation. There is no particularly strong correlation between LHCN and the 12 μm luminosity; in fact, of all the four IRAS bands, the 12 μm luminosity has the weakest correlation with the HCN luminosity. There is also no evidence of stronger HCN emission or a higher ratio of HCN and CO luminosities LHCN/LCO for galaxies with excess 12 μm emission. This result implies that mid-IR radiative pumping, or populating, of the J=1 level of HCN by a mid-IR vibrational transition is not important compared with the collisional excitation by dense molecular hydrogen. Furthermore, large velocity gradient calculations justify the use of HCN J=1-0 emission as a tracer of high-density molecular gas (>~3×104/τcm-3) and give an estimate of the mass of dense molecular gas from HCN observations. Therefore, LHCN may be used as a measure of the total mass of dense molecular gas, and the luminosity ratio LHCN/LCO may indicate the fraction of molecular gas that is dense.

  8. HCN - A plausible source of purines, pyrimidines and amino acids on the primitive earth

    NASA Technical Reports Server (NTRS)

    Ferris, J.-P.; Joshi, P. C.; Edelson, E. H.; Lawless, J. G.

    1978-01-01

    Dilute (0.1 M) solutions of HCN condense to oligomers at pH 9.2, and hydrolysis of these oligomers yields 4,5-dihydroxypyrimidine, orotic acid, 5-hydroxyuracil, adenine, 4-aminoimidazole-5-carboxamide, and amino acids. It is suggested that the three main classes of nitrogen-containing biomolecules - purines, pyrimidines, and amino acids may have originated from HCN on the primitive earth. It is also suggested that the presence of orotic acid and 4-aminoimidazole-5-carboxamide might indicate that contemporary biosynthetic pathways for nucleotides evolved from the compounds released on hydrolysis of HCN oligomers.

  9. Spatially Resolved HCN Absorption Features in the Circumnuclear Region of NGC 1052

    NASA Astrophysics Data System (ADS)

    Sawada-Satoh, Satoko; Roh, Duk-Gyoo; Oh, Se-Jin; Lee, Sang-Sung; Byun, Do-Young; Kameno, Seiji; Yeom, Jae-Hwan; Jung, Dong-Kyu; Kim, Hyo-Ryoung; Hwang, Ju-Yeon

    2016-10-01

    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-1, redshifted by 149 and 212 km s-1 with respect to the systemic velocity of the galaxy. The column density of the HCN molecule is estimated to be 1015-1016 cm-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.

  10. Vibrationally Excited HCN in the Luminous Infrared Galaxy NGC 4418

    NASA Astrophysics Data System (ADS)

    Sakamoto, Kazushi; Aalto, Susanne; Evans, Aaron S.; Wiedner, Martina C.; Wilner, David J.

    2010-12-01

    Infrared pumping and its effect on the excitation of HCN molecules can be important when using rotational lines of HCN to probe dense molecular gas in galaxy nuclei. We report the first extragalactic detection of (sub)millimeter rotational lines of vibrationally excited HCN, in the dust-enshrouded nucleus of the luminous infrared galaxy NGC 4418. We estimate the excitation temperature of Tvib ≈ 230 K between the vibrational ground and excited (v 2 = 1) states. This excitation is most likely due to infrared radiation. At this high vibrational temperature the path through the v 2 = 1 state must have a strong impact on the rotational excitation in the vibrational ground level, although it may not be dominant for all rotational levels. Our observations also revealed nearly confusion-limited lines of CO, HCN, HCO+, H13CN, HC15N, CS, N2H+, and HC3N at λ ~ 1 mm. Their relative intensities may also be affected by the infrared pumping.

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

    PubMed

    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.

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

    PubMed Central

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

    2015-01-01

    Purpose. 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. Methods. 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. Results. 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. Conclusions. 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. PMID:26030105

  13. A new ab initio potential energy surface for the collisional excitation of HCN by para- and ortho-H2

    NASA Astrophysics Data System (ADS)

    Denis-Alpizar, Otoniel; Kalugina, Yulia; Stoecklin, Thierry; Vera, Mario Hernández; Lique, François

    2013-12-01

    We present a new four-dimensional potential energy surface for the collisional excitation of HCN by H2. Ab initio calculations of the HCN-H2 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-H2 with the nitrogen pointing towards H2 at an intermolecular separation of 7.20 a0. The corresponding well depth is -195.20 cm-1. A secondary minimum of -183.59 cm-1 was found for a T-shape configuration with the H of HCN pointing to the center of mass of H2. We also determine the rovibrational energy levels of the HCN-para-H2 and HCN-ortho-H2 complexes. The calculated dissociation energies for the para and ortho complexes are 37.79 cm-1 and 60.26 cm-1, respectively. The calculated ro-vibrational transitions in the HCN-H2 complex are found to agree by more than 0.5% with the available experimental data, confirming the accuracy of the potential energy surface.

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

    NASA Astrophysics Data System (ADS)

    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< 17-70 pc) nuclei that have very high implied mid-infrared surface brightness > 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

  15. LOW CONDUCTANCE HCN1 ION CHANNELS AUGMENT THE FREQUENCY RESPONSE OF ROD AND CONE PHOTORECEPTORS

    PubMed Central

    Barrow, Andrew J.; Wu, Samuel M.

    2009-01-01

    Hyperpolarization-activated cyclic nucleotide gated (HCN) ion channels are expressed in several tissues throughout the body, including the heart, the CNS, and the retina. HCN channels are found in many neurons in the retina, but their most established role is in generating the hyperpolarization-activated current, Ih, in photoreceptors. This current makes the light response of rod and cone photoreceptors more transient, an effect similar to that of a high-pass filter. A unique property of HCN channels is their small single channel current, which is below the thermal noise threshold of measuring electronics. We use nonstationary fluctuation analysis (NSFA) in the intact retina to estimate the conductance of single HCN channels, revealing a conductance of approximately 650 fS in both rod and cone photoreceptors. We also analyze the properties of HCN channels in salamander rods and cones, from the biophysical to the functional level, showing that HCN1 is the predominant isoform in both cells, and demonstrate how HCN1 channels speed up the light response of both rods and cones under distinct adaptational conditions. We show that in rods and cones, HCN channels increase the natural frequency response of single cells by modifying the photocurrent input, which is limited in its frequency response by the speed of a molecular signaling cascade. In doing so, HCN channels form the first of several systems in the retina that augment the speed of the visual response, allowing an animal to perceive visual stimuli that change more quickly than the underlying photocurrent. PMID:19420251

  16. HCN2 channels in the ventral tegmental area regulate behavioral responses to chronic stress

    PubMed Central

    Zhong, Peng; Vickstrom, Casey R; Liu, Xiaojie; Hu, Ying; Yu, Laikang; Yu, Han-Gang

    2018-01-01

    Dopamine neurons in the ventral tegmental area (VTA) are powerful regulators of depression-related behavior. Dopamine neuron activity is altered in chronic stress-based models of depression, but the underlying mechanisms remain incompletely understood. Here, we show that mice subject to chronic mild unpredictable stress (CMS) exhibit anxiety- and depressive-like behavior, which was associated with decreased VTA dopamine neuron firing in vivo and ex vivo. Dopamine neuron firing is governed by voltage-gated ion channels, in particular hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. Following CMS, HCN-mediated currents were decreased in nucleus accumbens-projecting VTA dopamine neurons. Furthermore, shRNA-mediated HCN2 knockdown in the VTA was sufficient to recapitulate CMS-induced depressive- and anxiety-like behavior in stress-naïve mice, whereas VTA HCN2 overexpression largely prevented CMS-induced behavioral deficits. Together, these results reveal a critical role for HCN2 in regulating VTA dopamine neuronal activity and depressive-related behaviors. PMID:29256865

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

    PubMed

    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 < 0.05). However, this effect was probably due to the reduction of I Kr , which was also inhibited (63.5 ± 4.6%) by Cs + These results strongly suggest that f H regulation in the brown trout heart is largely independent on I f . Copyright © 2017 the American Physiological Society.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sawada-Satoh, Satoko; Roh, Duk-Gyoo; Oh, Se-Jin

    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 ofmore » 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.« less

  19. The HNC/HCN ratio in star-forming regions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

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

    2014-05-20

    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 staticmore » 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.« less

  20. The Physics and Chemistry of Small Translucent Molecular Clouds. VIII. HCN and HNC

    NASA Astrophysics Data System (ADS)

    Turner, B. E.; Pirogov, L.; Minh, Y. C.

    1997-07-01

    We have conducted a survey of HCN and HNC (two rotational transitions each) in our standard sample of 11 cirrus cores and 27 Clemens-Barvainis translucent cores whose structures and chemistry have been studied earlier in this series. Both species are seen in all 38 objects. HCNH+ has been searched in three objects. These results are modeled in terms of our previous hydrostatic equilibrium and n ~ r-α structures together with other chemical and physical properties derived earlier. A detailed program has been written to handle the complex radiative transfer of the hyperfine splitting (hfs) of HCN. It is shown that serious errors are made in deriving HCN abundances by methods that ignore the hfs. Both HCN and HNC abundances are high, typically 1(-8) in most sources. The chemically important ratio HCN/HNC is found to be ~2.5 if these species are spatially centrally peaked and ~6 if not. Both species abundances increase monotonically with increasing extinction in the 1.2-2.7 mag range (edge to center), thus displaying the same characteristic transition between diffuse and dense cloud chemistry as do most other species we have studied. HCN/HNC decreases with increasing extinction to a value of 1.3 at Av0 ~ 10, approaching the expected value of 1.0 for dense clouds. Two types of ion-molecule chemistry models have been carried out: a full model using the Standard Model rate file and comprising 409 species (by Lee and Herbst), and a simplified model comprising 21 nitrogen-bearing species for conditions relevant to translucent clouds. Good agreement between observations and chemistry models is achieved throughout the translucent extinction range. Important conclusions are that (1) neutral-neutral reactions such as N + CH2 dominate the chemistry of HCN; (2) low ion-polar reaction rates are strongly favored over high ones; (3) the reaction C+ + NH3 --> H2NC+ --> HNC is unimportant, thus largely uncoupling the CN and NH chemistries; (4) the ratio HCN/HNC is not a particularly

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

    NASA Technical Reports Server (NTRS)

    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.

  2. Loss of HCN1 enhances disease progression in mouse models of CNG channel-linked retinitis pigmentosa and achromatopsia.

    PubMed

    Schön, Christian; Asteriti, Sabrina; Koch, Susanne; Sothilingam, Vithiyanjali; Garcia Garrido, Marina; Tanimoto, Naoyuki; Herms, Jochen; Seeliger, Mathias W; Cangiano, Lorenzo; Biel, Martin; Michalakis, Stylianos

    2016-03-15

    Most inherited blinding diseases are characterized by compromised retinal function and progressive degeneration of photoreceptors. However, the factors that affect the life span of photoreceptors in such degenerative retinal diseases are rather poorly understood. Here, we explore the role of hyperpolarization-activated cyclic nucleotide-gated channel 1 (HCN1) in this context. HCN1 is known to adjust retinal function under mesopic conditions, and although it is expressed at high levels in rod and cone photoreceptor inner segments, no association with any retinal disorder has yet been found. We investigated the effects of an additional genetic deletion of HCN1 on the function and survival of photoreceptors in a mouse model of CNGB1-linked retinitis pigmentosa (RP). We found that the absence of HCN1 in Cngb1 knockout (KO) mice exacerbated photoreceptor degeneration. The deleterious effect was reduced by expression of HCN1 using a viral vector. Moreover, pharmacological inhibition of HCN1 also enhanced rod degeneration in Cngb1 KO mice. Patch-clamp recordings revealed that the membrane potentials of Cngb1 KO and Cngb1/Hcn1 double-KO rods were both significantly depolarized. We also found evidence for altered calcium homeostasis and increased activation of the protease calpain in Cngb1/Hcn1 double-KO mice. Finally, the deletion of HCN1 also exacerbated degeneration of cone photoreceptors in a mouse model of CNGA3-linked achromatopsia. Our results identify HCN1 as a major modifier of photoreceptor degeneration and suggest that pharmacological inhibition of HCN channels may enhance disease progression in RP and achromatopsia patients. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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

    NASA Astrophysics Data System (ADS)

    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

  4. HCN Polymers: Toward Structure Comprehension Using High Resolution Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed

    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.

  6. The structure and energetics of the HCN → HNC transition state

    NASA Astrophysics Data System (ADS)

    Lee, Timothy J.; Rendell, Alistair P.

    1991-03-01

    The optimum geometries and quadratic force constants of HCN, HNC and the transition state connecting them have been determined at the single and double excitation coupled-cluster (CCSD) and CCSD(T) levels of theory. Energy differences were evaluated using the CCSD and CCSD(T) methods in conjunction with large atomic natural orbital basis sets containing g-type basis functions on the heavy atoms and f-type functions on hydrogen. The most reliable structure obtained for the transition state has bond distances of 1.194, 1.188 and 1.389 Å for rCN, rCH and rNH, respectively. Including a correction for zero-point vibrational energies, the transition state is predicted to be 44.6 ± 1.0 kcal/mol above the HCN isomer, while HNC is predicted to be 14.4 ± 1.0 kcal/mol above HCN. The latter value is in excellent agreement with the most recent experimental determination (14.8 ± 2.0 kcal/mol).

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Imanishi, Masatoshi; Nakanishi, Kouichiro; Izumi, Takuma, E-mail: masa.imanishi@nao.ac.jp

    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.more » 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 +}.« less

  8. Simple Organics and Biomonomers Identified in HCN Polymers: An Overview

    PubMed Central

    Ruiz-Bermejo, Marta; Zorzano, María-Paz; Osuna-Esteban, Susana

    2013-01-01

    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. PMID:25369814

  9. HCN4-Overexpressing Mouse Embryonic Stem Cell-Derived Cardiomyocytes Generate a New Rapid Rhythm in Rats with Bradycardia.

    PubMed

    Saito, Yukihiro; Nakamura, Kazufumi; Yoshida, Masashi; Sugiyama, Hiroki; Takano, Makoto; Nagase, Satoshi; Morita, Hiroshi; Kusano, Kengo F; Ito, Hiroshi

    2018-05-30

    A biological pacemaker is expected to solve the persisting problems of an artificial cardiac pacemaker including short battery life, lead breaks, infection, and electromagnetic interference. We previously reported HCN4 overexpression enhances pacemaking ability of mouse embryonic stem cell-derived cardiomyocytes (mESC-CMs) in vitro. However, the effect of these cells on bradycardia in vivo has remained unclear. Therefore, we transplanted HCN4-overexpressing mESC-CMs into bradycardia model animals and investigated whether they could function as a biological pacemaker. The rabbit Hcn4 gene was transfected into mouse embryonic stem cells and induced HCN4-overexpressing mESC-CMs. Non-cardiomyocytes were removed under serum/glucose-free and lactate-supplemented conditions. Cardiac balls containing 5 × 10 3 mESC-CMs were made by using the hanging drop method. One hundred cardiac balls were injected into the left ventricular free wall of complete atrioventricular block (CAVB) model rats. Heart beats were evaluated using an implantable telemetry system 7 to 30 days after cell transplantation. The result showed that ectopic ventricular beats that were faster than the intrinsic escape rhythm were often observed in CAVB model rats transplanted with HCN4-overexpressing mESC-CMs. On the other hand, the rats transplanted with non-overexpressing mESC-CMs showed sporadic single premature ventricular contraction but not sustained ectopic ventricular rhythms. These results indicated that HCN4-overexpressing mESC-CMs produce rapid ectopic ventricular rhythms as a biological pacemaker.

  10. In-Situ Measurements of HCN and CH3CN in the Pacific Troposphere: Sources, Sinks, and Comparisons with Spectroscopic Observations

    NASA Technical Reports Server (NTRS)

    Singh, Hanwant B.; Salas, L.; Herlth, D.; Czech, E.; Viezee, W.; Li, Q.; Jacob, D. J.; Blake, D.; Sachse, G.; Harward, C. N.; hide

    2002-01-01

    We report the first in-situ measurements of hydrogen cyanide (HCN) and acetonitrile (CH3CN) from the Pacific troposphere (0-12 km) obtained during the NASA/Trace-P mission (Feb.-April, 2001). Mean HCN and CH3CN mixing ratios of 243 (+/-118) ppt and 149 (+/-56) ppt respectively, were measured. The in-situ observations correspond to a total HCN column of 4.4-4.9 x 10(exp 15) molec. cm(exp -2) and a CH3CN column of 2.8-3.0 x 10(exp 15) molec. cm(exp -2). This HCN column is in good agreement with available spectroscopic observations. The atmospheric concentrations of HCN and CH3CN were greatly influenced by outflow of pollution from Asia. There is a linear relationship between the mixing ratios of HCN and CH3CN, and in turn these are well correlated with tracers of biomass combustion (e.g. CH3Cl, CO). Relative enhancements with respect to known tracers of biomass combustion within selected plumes in the free troposphere, and pollution episodes in the boundary layer allow an estimation of a global biomass burning source of 0.8+/-0.4 Tg (N)/y for HCN and 0.4+/-0.1 Tg (N)/y for CH3CN. In comparison, emissions from automobiles and industry are quite small (<0.05 Tg (N)/y). The vertical structure of HCN and CH3CN indicated reduced mixing ratios in the MBL (Marine Boundary Layer). Using, a simple box model, the observed gradients across the top of the MBL are used to derive an oceanic flux of 6.7 x 10(exp -15) g (N) cm(exp -2)/s for HCN and 4.8 x 10(exp -15) g (N) cm(exp -2)/s for CH3CN. An air-sea exchange model is used to conclude that this flux can be maintained if the oceans are under-saturated in HCN and CH3CN by 23% and 17%, respectively. It is inferred that oceanic loss is a dominant sink for these nitrites, and they deposit some 1.3 Tg (N) of nitrogen annually to the oceans. Assuming reaction with OH radicals and loss to the oceans as the major removal processes, a mean atmospheric residence time of 4.7 months for HCN and 5.1 months for CH3CN is calculated. A global

  11. 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?

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Matsushita, Satoki; Trung, Dinh-V-; Boone, Frédéric

    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 bymore » 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.« less

  12. Improvement of the positive bias stability of a-IGZO TFTs by the HCN treatment

    NASA Astrophysics Data System (ADS)

    Kim, Myeong-Ho; Choi, Myung-Jea; Kimura, Katsuya; Kobayashi, Hikaru; Choi, Duck-Kyun

    2016-12-01

    In recent years, many researchers have attempted to improve the bias stability of amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs). In this study, the hydrogen cyanide (HCN) treatment was carried out to improve the positive bias stability of bottom-gate a-IGZO TFTs. The HCN treatment was performed using a 0.1 M HCN solution with a pH of 10 at room temperature. Before applying the positive bias stress, there were no differences in the major electrical properties, including the saturation mobility (μsat), threshold voltage (Vth), and subthreshold swing (S/S), between HCN-treated and non-HCN-treated devices. However, after applying the positive bias stress, the HCN-treated device showed superior bias stability compared to the non-HCN-treated device. This difference is associated with the passivation of the defect states and the surface of the back-channel layer of the HCN-treated device by cyanide ions.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Acetylene (C2H2) and hydrogen cyanide (HCN) from IASI satellite observations: global distributions, validation, and comparison with model

    NASA Astrophysics Data System (ADS)

    Duflot, V.; Wespes, C.; Clarisse, L.; Hurtmans, D.; Ngadi, Y.; Jones, N.; Paton-Walsh, C.; Hadji-Lazaro, J.; Vigouroux, C.; De Mazière, M.; Metzger, J.-M.; Mahieu, E.; Servais, C.; Hase, F.; Schneider, M.; Clerbaux, C.; Coheur, P.-F.

    2015-09-01

    We present global distributions of C2H2 and hydrogen cyanide (HCN) total columns derived from the Infrared Atmospheric Sounding Interferometer (IASI) for the years 2008-2010. These distributions are obtained with a fast method allowing to retrieve C2H2 abundance globally with a 5 % precision and HCN abundance in the tropical (subtropical) belt with a 10 % (25 %) precision. IASI data are compared for validation purposes with ground-based Fourier transform infrared (FTIR) spectrometer measurements at four selected stations. We show that there is an overall agreement between the ground-based and space measurements with correlation coefficients for daily mean measurements ranging from 0.28 to 0.81, depending on the site. Global C2H2 and subtropical HCN abundances retrieved from IASI spectra show the expected seasonality linked to variations in the anthropogenic emissions and seasonal biomass burning activity, as well as exceptional events, and are in good agreement with previous spaceborne studies. Total columns simulated by the Model for Ozone and Related Chemical Tracers, version 4 (MOZART-4) are compared to the ground-based FTIR measurements at the four selected stations. The model is able to capture the seasonality in the two species in most of the cases, with correlation coefficients for daily mean measurements ranging from 0.50 to 0.86, depending on the site. IASI measurements are also compared to the distributions from MOZART-4. Seasonal cycles observed from satellite data are reasonably well reproduced by the model with correlation coefficients ranging from -0.31 to 0.93 for C2H2 daily means, and from 0.09 to 0.86 for HCN daily means, depending on the considered region. However, the anthropogenic (biomass burning) emissions used in the model seem to be overestimated (underestimated), and a negative global mean bias of 1 % (16 %) of the model relative to the satellite observations was found for C2H2 (HCN).

  15. 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

    PubMed Central

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

    2017-01-01

    ABSTRACT 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 (Ih 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. PMID:28818840

  16. 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.

    PubMed

    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.

  17. Quantifying the emissions of HCN from on-road vehicles in urban areas

    NASA Astrophysics Data System (ADS)

    Moussa, S. G.; Leithead, A.; Wentzell, J. J.; Lu, G.; Li, S.; Brook, J.; Liggio, J.

    2013-12-01

    Hydrogen Cyanide (HCN), has been considered a marker for biomass burning emissions. Despite its adverse health impacts, estimate of its global sources and sinks are highly uncertain due to a limited number of field and laboratory studies. In particular, HCN emissions from automobile exhaust are not well constrained for modern vehicles, and thought to be relatively small compared to emissions from biomass burning. In the current study, HCN emissions from individual diesel and gasoline vehicles were quantified as a function of engine driving mode, and fuel type. Proton transfer Reaction-Time of Flight-Mass spectrometry (PTR-ToF-MS) was used to measure HCN emissions from diesel engines operating on ultra-low sulfur diesel (ULSD) and various bio-diesel blends including Soy, Tallow, and Canola. Significant emissions of HCN were observed from all vehicles, and enhanced with the use of biodiesel. In addition, ambient measurements of HCN in a traffic dominated urban area in Toronto, Canada demonstrated that a correlation between HCN, and traditional vehicle emissions markers such as benzene and xylenes exists and indicating that HCN has the potential to be a marker of fuel combustion. The ambient data and the calculated emission factors further suggest that vehicular emissions are a major source of HCN even in the presence of biomass burning, and that near roadway conditions may represent the dominant exposure pathway to HCN in urban areas. Results of this study have important implications on HCN global budget, health impacts in urban areas and the effect of alternate fuels on the emissions of this toxic species.

  18. HCN1 channels in cerebellar Purkinje cells promote late stages of learning and constrain synaptic inhibition

    PubMed Central

    Rinaldi, Arianna; Defterali, Cagla; Mialot, Antoine; Garden, Derek L F; Beraneck, Mathieu; Nolan, Matthew F

    2013-01-01

    Neural computations rely on ion channels that modify neuronal responses to synaptic inputs. While single cell recordings suggest diverse and neurone type-specific computational functions for HCN1 channels, their behavioural roles in any single neurone type are not clear. Using a battery of behavioural assays, including analysis of motor learning in vestibulo-ocular reflex and rotarod tests, we find that deletion of HCN1 channels from cerebellar Purkinje cells selectively impairs late stages of motor learning. Because deletion of HCN1 modifies only a subset of behaviours involving Purkinje cells, we asked whether the channel also has functional specificity at a cellular level. We find that HCN1 channels in cerebellar Purkinje cells reduce the duration of inhibitory synaptic responses but, in the absence of membrane hyperpolarization, do not affect responses to excitatory inputs. Our results indicate that manipulation of subthreshold computation in a single neurone type causes specific modifications to behaviour. PMID:24000178

  19. A NOVEL MUTATION IN THE HCN4 GENE CAUSES SYMPTOMATIC SINUS BRADYCARDIA IN MOROCCAN JEWS

    PubMed Central

    Laish-Farkash, Avishag; Brass, Dovrat; Marek-Yagel, Dina; Pras, Elon; Dascal, Nathan; Antzelevitch, Charles; Nof, Eyal; Reznik, Haya; Eldar, Michael; Glikson, Michael; Luria, David

    2010-01-01

    Objectives To conduct a clinical, genetic and functional analysis of three unrelated families with familial sinus bradycardia (FSB). Background Mutations in the hyperpolarization-activated nucleotide-gated channel (HCN4) are known to be associated with FSB. Methods and Results Three males of Moroccan Jewish descent were hospitalized: one survived an out-of-hospital cardiac arrest and 2 presented with weakness and presyncopal events. All 3 had significant sinus bradycardia, also found in other first-degree relatives, with a segregation suggesting autosomal-dominant inheritance. All had normal response to exercise and normal heart structure. Sequencing of the HCN4 gene in all patients revealed a C to T transition at nucleotide position 1454, which resulted in an alanine to valine change (A485V) in the ion channel pore found in most of their bradycardiac relatives, but not in 150 controls. Functional expression of the mutated ion channel in Xenopus oocytes and in human embryonic kidney 293 cells revealed profoundly reduced function and synthesis of the mutant channel compared to wild-type. Conclusions We describe a new mutation in the HCN4 gene causing symptomatic FSB in 3 unrelated individuals of similar ethnic background that may indicate unexplained FSB in this ethnic group. This profound functional defect is consistent with the symptomatic phenotype. PMID:20662977

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

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed

    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.

  2. Optical properties of poly-HCN and their astronomical applications

    NASA Technical Reports Server (NTRS)

    Khare, B. N.; Sagan, C.; Thompson, W. R.; Arakawa, E. T.; Meisse, C.; Tuminello, P. S.

    1994-01-01

    Matthews (1992) has proposed that HCN "polymer" is ubiquitous in the solar system. We apply vacuum deposition and spectroscopic techniques previously used on synthetic organic heteropolymers (tholins), kerogens, and meteoritic organic residues to the measurement of the optical constants of poly-HCN in the wavelength range 0.05-40 micrometers. These measurements allow quantitative comparison with spectrophotometry of organic-rich bodies in the outer solar system. In a specific test of Matthews' hypothesis, poly-HCN fails to match the optical constants of the haze of the Saturnian moon, Titan, in the visible and near-infrared derived from astronomical observations and standard models of the Titan atmosphere. In contrast, a tholin produced from a simulated Titan atmosphere matches within the probable errors. Poly-HCN is much more N-rich than Titan tholin.

  3. Detection of Macromolecular Fractions in HCN Polymers Using Electrophoretic and Ultrafiltration Techniques.

    PubMed

    Marín-Yaseli, Margarita R; Cid, Cristina; Yagüe, Ana I; Ruiz-Bermejo, Marta

    2017-02-01

    Elucidating the origin of life involves synthetic as well as analytical challenges. Herein, for the first time, we describe the use of gel electrophoresis and ultrafiltration to fractionate HCN polymers. Since the first prebiotic synthesis of adenine by Oró, HCN polymers have gained much interest in studies on the origins of life due to the identification of biomonomers and related compounds within them. Here, we demonstrate that macromolecular fractions with electrophoretic mobility can also be detected within HCN polymers. The migration of polymers under the influence of an electric field depends not only on their sizes (one-dimensional electrophoresis) but also their different isoelectric points (two-dimensional electrophoresis, 2-DE). The same behaviour was observed for several macromolecular fractions detected in HCN polymers. Macromolecular fractions with apparent molecular weights as high as 250 kDa were detected by tricine-SDS gel electrophoresis. Cationic macromolecular fractions with apparent molecular weights as high as 140 kDa were also detected by 2-DE. The HCN polymers synthesized were fractionated by ultrafiltration. As a result, the molecular weight distributions of the macromolecular fractions detected in the HCN polymers directly depended on the synthetic conditions used to produce these polymers. The implications of these results for prebiotic chemistry will be discussed. © 2017 Wiley-VHCA AG, Zurich, Switzerland.

  4. Submillimeter-HCN Diagram for Energy Diagnostics in the Centers of Galaxies

    NASA Astrophysics Data System (ADS)

    Izumi, Takuma; Kohno, Kotaro; Aalto, Susanne; Espada, Daniel; Fathi, Kambiz; Harada, Nanase; Hatsukade, Bunyo; Hsieh, Pei-Ying; Imanishi, Masatoshi; Krips, Melanie; Martín, Sergio; Matsushita, Satoki; Meier, David S.; Nakai, Naomasa; Nakanishi, Kouichiro; Schinnerer, Eva; Sheth, Kartik; Terashima, Yuichi; Turner, Jean L.

    2016-02-01

    Compiling data from literature and the Atacama Large Millimeter/submillimeter Array archive, we show enhanced HCN(4-3)/HCO+(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+ 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.

  5. HCN and HCO(+) images of the photodissociation region in the Orion Bar

    NASA Technical Reports Server (NTRS)

    Youngowl, Rolaine C.; Meixner, Margaret; Tielens, Alexander G. G. M.; Tauber, Jan A.

    1995-01-01

    We present preliminary millimeter-wavelength images of the photodissociation region (PDR) in the Orion Bar, observed with the Berkeley- Illinois-Maryland array (BIMA). These new BIMA observations have attained 5 arc sec resolution in the J=l-O emission lines of HCO+ (formyl ion) and HCN (hydrogen cyanide). The results are compared with previous observations of the J=1-0 transition lines of (13)CO. We find that the HCO+ and HCN have different spatial distributions. HCN appears to lie primarily inside dense clumps of gas, which are defined by areas of intense (13)CO emission. However, the HCO+ emission appears to be only loosely associated with the surfaces of the gas clumps. We suggest that HCO+ abundance is enhanced by the presence of vibrationally excited H2 on the surfaces of dense clumps, and that the HCN abundance is attenuated by photo destruction outside the cores of dense clumps of gas.

  6. CNG and HCN channels: two peas, one pod.

    PubMed

    Craven, Kimberley B; Zagotta, William N

    2006-01-01

    Cyclic nucleotide-activated ion channels play a fundamental role in a variety of physiological processes. By opening in response to intracellular cyclic nucleotides, they translate changes in concentrations of signaling molecules to changes in membrane potential. These channels belong to two families: the cyclic nucleotide-gated (CNG) channels and the hyperpolarization-activated cyclic nucleotide-modulated (HCN) channels. The two families exhibit high sequence similarity and belong to the superfamily of voltage-gated potassium channels. Whereas HCN channels are activated by voltage and CNG channels are virtually voltage independent, both channels are activated by cyclic nucleotide binding. Furthermore, the channels are thought to have similar channel structures, leading to similar mechanisms of activation by cyclic nucleotides. However, although these channels are structurally and behaviorally similar, they have evolved to perform distinct physiological functions. This review describes the physiological roles and biophysical behavior of CNG and HCN channels. We focus on how similarities in structure and activation mechanisms result in common biophysical models, allowing CNG and HCN channels to be viewed as a single genre.

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

    NASA Astrophysics Data System (ADS)

    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.

  8. Stratospheric distribution of HCN from far infrared observations

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Guo, J.; Carli, B.; Mencaraglia, F.; Carlotti, M.

    1987-01-01

    Far infrared limb thermal emission measurements of the earth's stratosphere were made with a high resolution spectrometer on a balloon payload launched from Palestine, TX, on Oct. 5, 1982. Several limb sequences of a portion of the observed spectra have been analyzed for retrieval of the stratospheric HCN profile from a number of spectral lines in the 32 to 56 cm region. The mixing ratio profile in the 20 to 37 km altitude range has been retrieved with 2-sigma uncertainties of about 4-5 km. The HCN volume mixing ratio is found to be about 139 pptv at 20 km, 127 pptv at 25 km, and increasing to 172 pptv at 37 km. The results are compared with measurements by other groups and with photochemical model calculations reported in the literature.

  9. HCN Production via Impact Ejecta Reentry During the Late Heavy Bombardment

    NASA Astrophysics Data System (ADS)

    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.

  10. Novel HCN2 mutation contributes to febrile seizures by shifting the channel's kinetics in a temperature-dependent manner.

    PubMed

    Nakamura, Yuki; Shi, Xiuyu; Numata, Tomohiro; Mori, Yasuo; Inoue, Ryuji; Lossin, Christoph; Baram, Tallie Z; Hirose, Shinichi

    2013-01-01

    Hyperpolarization-activated cyclic nucleotide-gated (HCN) channel-mediated currents, known as I h, are involved in the control of rhythmic activity in neuronal circuits and in determining neuronal properties including the resting membrane potential. Recent studies have shown that HCN channels play a role in seizure susceptibility and in absence and limbic epilepsy including temporal lobe epilepsy following long febrile seizures (FS). This study focused on the potential contributions of abnormalities in the HCN2 isoform and their role in FS. A novel heterozygous missense mutation in HCN2 exon 1 leading to p.S126L was identified in two unrelated patients with FS. The mutation was inherited from the mother who had suffered from FS in a pedigree. To determine the effect of this substitution we conducted whole-cell patch clamp electrophysiology. We found that mutant channels had elevated sensitivity to temperature. More specifically, they displayed faster kinetics at higher temperature. Kinetic shift by change of temperature sensitivity rather than the shift of voltage dependence led to increased availability of I h in conditions promoting FS. Responses to cyclic AMP did not differ between wildtype and mutant channels. Thus, mutant HCN2 channels cause significant cAMP-independent enhanced availability of I h during high temperatures, which may contribute to hyperthermia-induced neuronal hyperexcitability in some individuals with FS.

  11. Photodissociation Dynamics of Vinyl Cyanide Studied by Chirped-Pulse Millimeter-Wave Spectroscopy of HCN and HNC Products

    NASA Astrophysics Data System (ADS)

    Prozument, Kirill; Shaver, Rachel G.; Baraban, Joshua H.; Park, G. Barratt; Suits, Arthur G.; Muenter, John S.; Field, Robert W.

    2013-06-01

    Vinyl cyanide 193 nm photodissociation has been studied using Chirped-Pulse Millimeter-Wave (CPmmW) spectroscopy. J = 0 - 1 transitions of more than 30 vibrationally excited states of the HCN and HNC products have been recorded and assigned within the 7 GHz wide chirp range. Bending excitations of HCN up to v_2 = 14, leading toward the HCN leftrightarrow HNC isomerization transition state, are detected and interpreted in terms of their electric quadrupole, (eQq)_{N}, and rotational, B_v, constants. The photolysis reaction transition states were probed using both normal vinyl cyanide, CH_2=CHCN, and its singly-deuterated isotopologue, CH_2=CDCN. The observed difference in the vibrational population distribution (VPD) obtained from the integrated intensities of the HCN and DCN products from the CH_2=CHCN vs. CH_2=CDCN photolysis reactions, suggests the relative unimportance of the three-center elimination mechanism for HCN production. On the other hand, the similarity in the observed VPD and overall intensities of HCN from CH_2=CHCN and CH_2=CDCN photolysis suggests four-center elimination as the major mechanism leading to the HCN product. Additional J - (J + 1) transitions would be required to characterize both the vibrational and the rotational state distributions of the products, which would permit more complete characterization of the transition state(s). The authors thank the Department of Energy, and KP thanks the ACS Petroleum Research Fund for their support of this work.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. The puzzle of HCN in comets: Is it both a product and a primary species?

    NASA Astrophysics Data System (ADS)

    Mumma, M.; Bonev, B.; Charnley, S.; Cordiner, M.; DiSanti, M.; Gibb, E.; Magee-Sauer, K.; Paganini, L.; Villanueva, G.

    2014-07-01

    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: - HCN is often used as a proxy for water when the dominant species (H_2O) is not available for simultaneous measurement, as at radio wavelengths. If much HCN is sometimes produced in the coma, its adoption as a water proxy could introduce unwanted bias to taxonomies based on composition. - HCN is one of the few volatile carriers of nitrogen accessible to remote sensing, with NH_3 being the dominant nitrile. If HCN is mainly a product species, its precursor becomes the more important metric for compiling a taxonomic classification based on nitrogen chemistry. - The stereoisomer HNC is regarded as a product species, thought to result from coma chemistry involving HCN. But, could another reaction of a primary precursor (X-CN) with a hydrocarbon co-produce both HNC and HCN? - The production rate for CN greatly exceeds the possible production from HCN in some comets, demonstrating the presence of another (more important) precursor of CN radicals in them. - The production rates of HCN measured through rotational (radio) and vibrational (infrared) spectroscopy agree in some comets, but in others the infrared rate exceeds the radio rate substantially. Is prompt emission from vibrationally excited HCN responsible? - 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 (H_2O, CH_3OH), 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). We will present the

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

    NASA Astrophysics Data System (ADS)

    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.

  15. Hcn1 Is a Tremorgenic Genetic Component in a Rat Model of Essential Tremor

    PubMed Central

    Ohno, Yukihiro; Shimizu, Saki; Tatara, Ayaka; Imaoku, Takuji; Ishii, Takahiro; Sasa, Masashi; Serikawa, Tadao; Kuramoto, Takashi

    2015-01-01

    Genetic factors are thought to play a major role in the etiology of essential tremor (ET); however, few genetic changes that induce ET have been identified to date. In the present study, to find genes responsible for the development of ET, we employed a rat model system consisting of a tremulous mutant strain, TRM/Kyo (TRM), and its substrain TRMR/Kyo (TRMR). The TRM rat is homozygous for the tremor (tm) mutation and shows spontaneous tremors resembling human ET. The TRMR rat also carries a homozygous tm mutation but shows no tremor, leading us to hypothesize that TRM rats carry one or more genes implicated in the development of ET in addition to the tm mutation. We used a positional cloning approach and found a missense mutation (c. 1061 C>T, p. A354V) in the hyperpolarization-activated cyclic nucleotide-gated 1 channel (Hcn1) gene. The A354V HCN1 failed to conduct hyperpolarization-activated currents in vitro, implicating it as a loss-of-function mutation. Blocking HCN1 channels with ZD7288 in vivo evoked kinetic tremors in nontremulous TRMR rats. We also found neuronal activation of the inferior olive (IO) in both ZD7288-treated TRMR and non-treated TRM rats and a reduced incidence of tremor in the IO-lesioned TRM rats, suggesting a critical role of the IO in tremorgenesis. A rat strain carrying the A354V mutation alone on a genetic background identical to that of the TRM rats showed no tremor. Together, these data indicate that body tremors emerge when the two mutant loci, tm and Hcn1A354V, are combined in a rat model of ET. In this model, HCN1 channels play an important role in the tremorgenesis of ET. We propose that oligogenic, most probably digenic, inheritance is responsible for the genetic heterogeneity of ET. PMID:25970616

  16. A conserved tripeptide in CNG and HCN channels regulates ligand gating by controlling C-terminal oligomerization.

    PubMed

    Zhou, Lei; Olivier, Nelson B; Yao, Huan; Young, Edgar C; Siegelbaum, Steven A

    2004-12-02

    Cyclic nucleotides directly enhance the opening of the tetrameric CNG and HCN channels, although the mechanism remains unclear. We examined why HCN and certain CNG subunits form functional homomeric channels, whereas other CNG subunits only function in heteromeric channels. The "defect" in the CNGA4 subunit that prevents its homomeric expression was localized to its C-linker, which connects the transmembrane domain to the binding domain and contains a tripeptide that decreases the efficacy of ligand gating. Remarkably, replacement of the homologous HCN tripeptide with the CNGA4 sequence transformed cAMP into an inverse agonist that inhibits HCN channel opening. Using analytical ultracentrifugation, we identified the structural basis for this gating switch: whereas cAMP normally enhances the assembly of HCN C-terminal domains into a tetrameric gating ring, inclusion of the CNGA4 tripeptide reversed this action so that cAMP now causes gating ring disassembly. Thus, ligand gating depends on the dynamic oligomerization of C-terminal binding domains.

  17. Novel exon 1 protein-coding regions N-terminally extend human KCNE3 and KCNE4.

    PubMed

    Abbott, Geoffrey W

    2016-08-01

    The 5 human (h)KCNE β subunits each regulate various cation channels and are linked to inherited cardiac arrhythmias. Reported here are previously undiscovered protein-coding regions in exon 1 of hKCNE3 and hKCNE4 that extend their encoded extracellular domains by 44 and 51 residues, which yields full-length proteins of 147 and 221 residues, respectively. Full-length hKCNE3 and hKCNE4 transcript and protein are expressed in multiple human tissues; for hKCNE4, only the longer protein isoform is detectable. Two-electrode voltage-clamp electrophysiology revealed that, when coexpressed in Xenopus laevis oocytes with various potassium channels, the newly discovered segment preserved conversion of KCNQ1 by hKCNE3 to a constitutively open channel, but prevented its inhibition of Kv4.2 and KCNQ4. hKCNE4 slowing of Kv4.2 inactivation and positive-shifted steady-state inactivation were also preserved in the longer form. In contrast, full-length hKCNE4 inhibition of KCNQ1 was limited to 40% at +40 mV vs. 80% inhibition by the shorter form, and augmentation of KCNQ4 activity by hKCNE4 was entirely abolished by the additional segment. Among the genome databases analyzed, the longer KCNE3 is confined to primates; full-length KCNE4 is widespread in vertebrates but is notably absent from Mus musculus Findings highlight unexpected KCNE gene diversity, raise the possibility of dynamic regulation of KCNE partner modulation via splice variation, and suggest that the longer hKCNE3 and hKCNE4 proteins should be adopted in future mechanistic and genetic screening studies.-Abbott, G. W. Novel exon 1 protein-coding regions N-terminally extend human KCNE3 and KCNE4. © FASEB.

  18. Structural basis for modulation and agonist specificity of HCN pacemaker channels.

    PubMed

    Zagotta, William N; Olivier, Nelson B; Black, Kevin D; Young, Edgar C; Olson, Rich; Gouaux, Eric

    2003-09-11

    The family of hyperpolarization-activated, cyclic nucleotide-modulated (HCN) channels are crucial for a range of electrical signalling, including cardiac and neuronal pacemaker activity, setting resting membrane electrical properties and dendritic integration. These nonselective cation channels, underlying the I(f), I(h) and I(q) currents of heart and nerve cells, are activated by membrane hyperpolarization and modulated by the binding of cyclic nucleotides such as cAMP and cGMP. The cAMP-mediated enhancement of channel activity is largely responsible for the increase in heart rate caused by beta-adrenergic agonists. Here we have investigated the mechanism underlying this modulation by studying a carboxy-terminal fragment of HCN2 containing the cyclic nucleotide-binding domain (CNBD) and the C-linker region that connects the CNBD to the pore. X-ray crystallographic structures of this C-terminal fragment bound to cAMP or cGMP, together with equilibrium sedimentation analysis, identify a tetramerization domain and the mechanism for cyclic nucleotide specificity, and suggest a model for ligand-dependent channel modulation. On the basis of amino acid sequence similarity to HCN channels, the cyclic nucleotide-gated, and eag- and KAT1-related families of channels are probably related to HCN channels in structure and mechanism.

  19. Energy yields for hydrogen cyanide and formaldehyde syntheses - The HCN and amino acid concentrations in the primitive ocean

    NASA Technical Reports Server (NTRS)

    Stribling, Roscoe; Miller, Stanley L.

    1987-01-01

    Simulated prebiotic atmospheres containing either CH4, CO, or CO2, in addition to N2, H2O, and variable amounts of H2, were subjected to the spark from a high-frequency Tesla coil, and the energy yields for the syntheses of HCN and H2CO were estimated from periodic (every two days) measurements of the compound concentrations. The mixtures with CH4 were found to yield the highest amounts of HCN, whereas the CO mixtures produced the highest yields of H2CO. These results model atmospheric corona discharges. From the yearly energy yields calculated and the corona discharge available on the earth, the yearly production rate of HCN was estimated; using data on the HCN production rates and the experimental rates of decomposition of amino acids through the submarine vents, the steady state amino acid production rate in the primitive ocean was calculated to be about 10 nmoles/sq cm per year.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jin, Mihwa; Lee, Jeong-Eun; Kim, Kee-Tae, E-mail: mihwajin.sf@gmail.com, E-mail: jeongeun.lee@khu.ac.kr, E-mail: ktkim@kasi.re.kr

    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 showmore » 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.« less

  1. Association reactions at low pressure. 5: The CH3(+)/HCN system. A final word?

    NASA Technical Reports Server (NTRS)

    Anicich, Vincent G.; Sen, Atish D.; Huntress, Wesley, Jr.; McEwan, Murray J.

    1995-01-01

    The reaction of the methyl cation with hydrogen cyanide is revisited. We have confidence that we have resolved a long standing apparent contradiction of experimental results. A literature history is presented along with one new experiment and a re-examination of an old experiment. In this present work it is shown that all of the previous studies had made consistent observations. Yet, each of the previous studies failed to observe all of the information present. The methyl cation does react with HCN by radiative association, a fact which had been in doubt. The product ions formed in the two-body and three-body processes react differently with HCN. The collisionally stabilized association product formed by a three-body mechanism, does not react with HCN and is readily detected in the experiments. The radiatively stabilized association product, formed by a slow two-body reaction, is not detected because it reacts with HCN by a fast proton transfer reaction forming the protonated HCN ion. Previous studies either 'lost' this product in the extremely large protonated HCN signal that is always present when HCN is used, or discounted it for various reasons. We have been able to show by ion cyclotron resonance (ICR) techniques (both FT-ICR and tandem ICR-dempster-ICR) that the radiative association product does react with the HCN to form the protonated HCN ion.

  2. A Submillimeter HCN Laser in IRC +10216.

    PubMed

    Schilke; Mehringer; Menten

    2000-01-01

    We report the detection of a strong submillimeter-wavelength HCN laser line at a frequency near 805 GHz toward the carbon star IRC +10216. This line, the J=9-8 rotational transition within the (0400) vibrationally excited state, is one of a series of HCN laser lines that were first detected in the laboratory in the early days of laser spectroscopy. Since its lower energy level is 4200 K above the ground state, the laser emission must arise from the innermost part of IRC +10216's circumstellar envelope. To better characterize this environment, we observed other, thermally emitting, vibrationally excited HCN lines and found that they, like the laser line, arise in a region of temperature approximately 1000 K that is located within the dust formation radius; this conclusion is supported by the line width of the laser. The (0400), J=9-8 laser might be chemically pumped and may be the only known laser (or maser) that is excited both in the laboratory and in space by a similar mechanism.

  3. THE NITROGEN ISOTOPIC COMPOSITION OF METEORITIC HCN

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pizzarello, Sandra, E-mail: pizzar@asu.edu

    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 organicmore » 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.« less

  4. HCN and chromophore formation on Jupiter

    NASA Technical Reports Server (NTRS)

    Ferris, James P.; Ishikawa, Yoji

    1987-01-01

    Reaction paths for the formation of HCN and chromophores on Jupiter are suggested. The reactions involve photolysis of ammonia/acetylene mixtures. Experimental data supporting these pathways are reported.

  5. Up-regulation of Hyperpolarization-activated Cyclic Nucleotide-gated Channel 3 (HCN3) by Specific Interaction with K+ Channel Tetramerization Domain-containing Protein 3 (KCTD3)*

    PubMed Central

    Cao-Ehlker, Xiaochun; Zong, Xiangang; Hammelmann, Verena; Gruner, Christian; Fenske, Stefanie; Michalakis, Stylianos; Wahl-Schott, Christian; Biel, Martin

    2013-01-01

    Most ion channels consist of the principal ion-permeating core subunit(s) and accessory proteins that are assembled with the channel core. The biological functions of the latter proteins are diverse and include the regulation of the biophysical properties of the ion channel, its connection to signaling pathways and the control of its cell surface expression. There is recent evidence that native hyperpolarization-activated cyclic nucleotide-gated channel complexes (HCN14) also contain accessory subunits, among which TRIP8b (tetratricopeptide repeat-containing Rab8b-interacting protein) has been most extensively studied. Here, we identify KCTD3, a so far uncharacterized member of the potassium channel tetramerization-domain containing (KCTD) protein family as an HCN3-interacting protein. KCTD3 is widely expressed in brain and some non-neuronal tissues and colocalizes with HCN3 in specific regions of the brain including hypothalamus. Within the HCN channel family, KCTD3 specifically binds to HCN3 and leads to a profound up-regulation of cell surface expression and current density of this channel. HCN3 can also functionally interact with TRIP8b; however, we found no evidence for channel complexes containing both TRIP8b and KCTD3. The C terminus of HCN3 is crucially required for functional interaction with KCTD3. Replacement of the cytosolic C terminus of HCN2 by the corresponding domain of HCN3 renders HCN2 sensitive to regulation by KCTD3. The C-terminal-half of KCTD3 is sufficient for binding to HCN3. However, the complete protein including the N-terminal tetramerization domain is needed for HCN3 current up-regulation. Together, our experiments indicate that KCTD3 is an accessory subunit of native HCN3 complexes. PMID:23382386

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Radiative transfer of HCN: interpreting observations of hyperfine anomalies

    NASA Astrophysics Data System (ADS)

    Mullins, A. M.; Loughnane, R. M.; Redman, M. P.; Wiles, B.; Guegan, N.; Barrett, J.; Keto, E. R.

    2016-07-01

    Molecules with hyperfine splitting of their rotational line spectra are useful probes of optical depth, via the relative line strengths of their hyperfine components. The hyperfine splitting is particularly advantageous in interpreting the physical conditions of the emitting gas because with a second rotational transition, both gas density and temperature can be derived. For HCN however, the relative strengths of the hyperfine lines are anomalous. They appear in ratios which can vary significantly from source to source, and are inconsistent with local thermodynamic equilibrium (LTE). This is the HCN hyperfine anomaly, and it prevents the use of simple LTE models of HCN emission to derive reliable optical depths. In this paper, we demonstrate how to model HCN hyperfine line emission, and derive accurate line ratios, spectral line shapes and optical depths. We show that by carrying out radiative transfer calculations over each hyperfine level individually, as opposed to summing them over each rotational level, the anomalous hyperfine emission emerges naturally. To do this requires not only accurate radiative rates between hyperfine states, but also accurate collisional rates. We investigate the effects of different sets of hyperfine collisional rates, derived via the proportional method and through direct recoupling calculations. Through an extensive parameter sweep over typical low-mass star-forming conditions, we show the HCN line ratios to be highly variable to optical depth. We also reproduce an observed effect whereby the red-blue asymmetry of the hyperfine lines (an infall signature) switches sense within a single rotational transition.

  8. On-board Measurement of HCN and NH3 Emissions from Vehicles During Real-World Driving

    NASA Astrophysics Data System (ADS)

    Moss, J. A.; Baum, M. M.

    2013-12-01

    Emission control systems in light-duty motor vehicles have played an important role in improving regional air quality by dramatically reducing the concentration of criteria pollutants (carbon monoxide, hydrocarbons, and nitrogen oxides) in exhaust emissions. Unintended side-reactions occurring on the surface of three-way catalysts can, however, lead to emission of non-criteria pollutants such as ammonia (NH3) and hydrogen cyanide (HCN). A pair of spectrometers based on tunable diode lasers (TDL) emitting in the near-infrared (1529 nm) and mid-infrared (2975 nm) have been developed for determination of HCN and acetylene (C2H2) emission rates from light-duty motor vehicles in real-time, while driving. Both spectrometers have been evaluated extensively using standard gas mixtures in the laboratory and exhaust from idling and moving vehicles. The TDL spectrometers were incorporated into an on-board instrument suite containing instrumentation for measurement of CO2, HCN, C2H2, NH3 and amines, and exhaust flow rate. On-board measurements were carried out on a fleet of ten vehicles driving a 30 minute circuit representative of real-world urban driving conditions. These measurements afforded emission factors for NH3 (194 × 147 mg km-1) and HCN (3.33 × 3.61 mg km-1), as well as the first report of methylamine emission factors, 0.70 × 0.61 mg km-1. Emissions of both amines were highly correlated (R2 = 0.95). The temporally-resolved TDL spectrometer measurements indicate that the highest HCN and C2H2 emissions occur during specific emission modes that are a function of driving conditions.

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

    NASA Astrophysics Data System (ADS)

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

    2018-02-01

    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 NH4CN 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 NH4CN, 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.

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. Chemical evolution. XXII - The hydantoins released on hydrolysis of HCN oligomers

    NASA Technical Reports Server (NTRS)

    Ferris, J. P.; Wos, J. D.; Lobo, A. P.

    1974-01-01

    The isolation of three hydantoins from HCN oligomers is described. One of these hydantoins, 5-carboxymethylidine hydantoin (5-CMH), rearranges to pyrimidine orotic acid in basic solution. The isolation of 5-CMH suggests the possibility that pyrimidines were formed directly from HCN on the primitive earth.

  13. The abundance of HCN in circumstellar envelopes of AGB stars of different chemical type

    NASA Astrophysics Data System (ADS)

    Schöier, F. L.; Ramstedt, S.; Olofsson, H.; Lindqvist, M.; Bieging, J. H.; Marvel, K. B.

    2013-02-01

    Aims: A multi-transition survey of HCN (sub-) millimeter line emission from a large sample of asymptotic giant branch (AGB) stars of different chemical type is presented. The data are analysed and circumstellar HCN abundances are estimated. The sample stars span a large range of properties such as mass-loss rate and photospheric C/O-ratio. The analysis of the new data allows for more accurate estimates of the circumstellar HCN abundances and puts new constraints on chemical models. Methods: In order to constrain the circumstellar HCN abundance distribution a detailed non-local thermodynamic equilibrium (LTE) excitation analysis, based on the Monte Carlo method, is performed. Effects of line overlaps and radiative excitation from dust grains are included. Results: The median values for the derived abundances of HCN (with respect to H2) are 3 × 10-5, 7 × 10-7 and 10-7 for carbon stars (25 stars), S-type AGB stars (19 stars) and M-type AGB stars (25 stars), respectively. The estimated sizes of the HCN envelopes are similar to those obtained in the case of SiO for the same sample of sources and agree well with previous results from interferometric observations, when these are available. Conclusions: We find that there is a clear dependence of the derived circumstellar HCN abundance on the C/O-ratio of the star, in that carbon stars have about two orders of magnitude higher abundances than M-type AGB stars, on average. The derived HCN abundances of the S-type AGB stars have a larger spread and typically fall in between those of the two other types, however, slightly closer to the values for the M-type AGB stars. For the M-type stars, the estimated abundances are much higher than what would be expected if HCN is formed in thermal equilibrium. However, the results are also in contrast to predictions from recent non-LTE chemical models, where very little difference is expected in the HCN abundances between the various types of AGB stars. This publication is based on data

  14. ALMA Multiple-transition Molecular Line Observations of the Ultraluminous Infrared Galaxy IRAS 20551-4250: Different HCN, HCO+, and HNC Excitation, and Implications for Infrared Radiative Pumping

    NASA Astrophysics Data System (ADS)

    Imanishi, Masatoshi; Nakanishi, Kouichiro; Izumi, Takuma

    2017-11-01

    We present our ALMA multi-transition molecular line observational results for the ultraluminous infrared galaxy IRAS 20551-4250, which is known to contain a luminous buried active galactic nucleus and shows detectable vibrationally excited (v 2 = 1f) HCN and HNC emission lines. The rotational J = 1-0, 4-3, and 8-7 of HCN, {{HCO}}+, and HNC emission lines were clearly detected at a vibrational ground level (v = 0). Vibrationally excited (v 2 = 1f) J = 4-3 emission lines were detected for HCN and HNC, but not for {{HCO}}+. Their observed flux ratios further support our previously obtained suggestion, based on J = 3-2 data, that (1) infrared radiative pumping plays a role in rotational excitation at v = 0, at least for HCN and HNC, and (2) HCN abundance is higher than {{HCO}}+ and HNC. The flux measurements of the isotopologue H13CN, {{{H}}}13{{CO}}+, and HN13C J = 3-2 emission lines support the higher HCN abundance scenario. Based on modeling with collisional excitation, we constrain the physical properties of these line-emitting molecular gases, but find that higher HNC rotational excitation than HCN and {{HCO}}+ is difficult to explain, due to the higher effective critical density of HNC. We consider the effects of infrared radiative pumping using the available 5-30 μm infrared spectrum and find that our observational results are well-explained if the radiation source is located at 30-100 pc from the molecular gas. The simultaneously covered very bright CO J = 3-2 emission line displays a broad emission wing, which we interpret as being due to molecular outflow activity with the estimated rate of ˜ 150 {M}⊙ {{yr}}-1.

  15. New CO and HCN sources associated with IRAS carbon stars

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Baclofen ameliorates spatial working memory impairments induced by chronic cerebral hypoperfusion via up-regulation of HCN2 expression in the PFC in rats.

    PubMed

    Luo, Pan; Chen, Cheng; Lu, Yun; Fu, TianLi; Lu, Qing; Xu, Xulin; Li, Changjun; He, Zhi; Guo, Lianjun

    2016-07-15

    Chronic cerebral hypoperfusion (CCH) causes memory deficits and increases the risk of vascular dementia (VD) through several biologically plausible pathways. However, whether CCH causes prefrontal cortex (PFC)-dependent spatial working memory impairments and Baclofen, a GABAB receptor agonist, could ameliorate the impairments is still not clear especially the mechanisms underlying the process. In this study, rats were subjected to permanent bilateral occlusion of the common carotid arteries (two-vessel occlusion, 2VO) to induce CCH. Two weeks later, rats were treated with 25mg/kg Baclofen (intraperitioneal injection, i.p.) for 3 weeks. Spatial working memory was evaluated in a Morris water maze using a modified delayed matching-to-place (DMP) procedure. Western blotting and immunohistochemistry were used to quantify the protein levels and protein localization. Our results showed that 2VO caused striking spatial working memory impairments, accompanied with a decreased HCN2 expression in PFC, but the protein levels of protein gene product 9.5 (PGP9.5, a neuron specific protein), glial fibrillary acidic protein (GFAP), synaptophysin (SYP), brain-derived neurotrophic factor (BDNF), parvalbumin (PV) and HCN1 were not distinguishably changed as compared with sham-operated rats. Baclofen treatment significantly improved the spatial working memory impairments caused by 2VO, accompanied with a reversion of 2VO-induced down-regulation of HCN2. Furthermore, there was a co-localization of HCN2 subunits and parvalbumin-positive neurons in PFC. Therefore, HCN2 may target inhibitory interneurons that is implicated in working memory processes, which may be a possible mechanism of the up-regulation of HCN2 by Baclofen treatment that reliefs spatial working memory deficits in rats with CCH. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Output power stability of a HCN laser using a stepping motor for the EAST interferometer system

    NASA Astrophysics Data System (ADS)

    Zhang, J. B.; Wei, X. C.; Liu, H. Q.; Shen, J. J.; Zeng, L.; Jie, Y. X.

    2015-11-01

    The HCN laser on EAST is a continuous wave glow discharge laser with 3.4 m cavity length and 120 mW power output at 337 μ m wavelength. Without a temperature-controlled system, the cavity length of the laser is very sensitive to the environmental temperature. An external power feedback control system is applied on the HCN laser to stabilize the laser output power. The feedback system is composed of a stepping motor, a PLC, a supervisory computer, and the corresponding control program. One step distance of the stepping motor is 1 μ m and the time response is 0.5 s. Based on the power feedback control system, a stable discharge for the HCN laser is obtained more than eight hours, which satisfies the EAST experiment.

  19. Distribution and Function of HCN Channels in the Apical Dendritic Tuft of Neocortical Pyramidal Neurons

    PubMed Central

    Harnett, Mark T.; Magee, Jeffrey C.

    2015-01-01

    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. PMID:25609619

  20. Diode laser absorption measurement and analysis of HCN in atmospheric-pressure, fuel-rich premixed methane/air flames

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gersen, S.; Mokhov, A.V.; Levinsky, H.B.

    Measurements of HCN in flat, fuel-rich premixed methane/air flames at atmospheric pressure are reported. Quartz-microprobe sampling followed by wavelength modulation absorption spectroscopy with second harmonic detection was used to obtain an overall measurement uncertainty of better than 20% for mole fractions HCN on the order of 10 ppm. The equivalence ratio, {phi}, was varied between 1.3 and 1.5, while the flame temperature was varied independently by changing the mass flux through the burner surface at constant equivalence ratio. Under the conditions of the experiments, the peak mole fractions vary little, in the range of 10-15 ppm. Increasing the flame temperaturemore » by increasing the mass flux had little influence on the peak mole fraction, but accelerated HCN burnout substantially. At high equivalence ratio and low flame temperature, HCN burnout is very slow: at {phi}=1.5, {proportional_to}10ppm HCN is still present 7 mm above the burner surface. Substantial quantitative disagreement is observed between the experimental profiles and those obtained from calculations using GRI-Mech 3.0, with the calculations generally overpredicting the results significantly. Changing the rates of key formation and consumption reactions for HCN can improve the agreement, but only by making unreasonable changes in these rates. Inclusion of reactions describing NCN formation and consumption in the calculations improves the agreement with the measurements considerably. (author)« less

  1. Structural basis for the mutual antagonism of cAMP and TRIP8b in regulating HCN channel function

    PubMed Central

    Saponaro, Andrea; Pauleta, Sofia R.; Cantini, Francesca; Matzapetakis, Manolis; Hammann, Christian; Donadoni, Chiara; Hu, Lei; Thiel, Gerhard; Banci, Lucia; Santoro, Bina; Moroni, Anna

    2014-01-01

    cAMP signaling in the brain mediates several higher order neural processes. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels directly bind cAMP through their cytoplasmic cyclic nucleotide binding domain (CNBD), thus playing a unique role in brain function. Neuronal HCN channels are also regulated by tetratricopeptide repeat-containing Rab8b interacting protein (TRIP8b), an auxiliary subunit that antagonizes the effects of cAMP by interacting with the channel CNBD. To unravel the molecular mechanisms underlying the dual regulation of HCN channel activity by cAMP/TRIP8b, we determined the NMR solution structure of the HCN2 channel CNBD in the cAMP-free form and mapped on it the TRIP8b interaction site. We reconstruct here the full conformational changes induced by cAMP binding to the HCN channel CNBD. Our results show that TRIP8b does not compete with cAMP for the same binding region; rather, it exerts its inhibitory action through an allosteric mechanism, preventing the cAMP-induced conformational changes in the HCN channel CNBD. PMID:25197093

  2. Satellite Boreal Measurements over Alaska and Canada During June-July 2004: Simultaneous Measurements of Upper Tropospheric CO, C2H6, HCN, CH3Cl, CH4, C2H2, CH2OH, HCOOH, OCS, and SF6 Mixing Ratios

    NASA Technical Reports Server (NTRS)

    Rinsland, Curtis P.; Dufour, Gaelle; Boone, Chris D.; Bernath, Peter F.; Chiou, Linda; Coheur, Pierre-Francois; Turquety, Solene; Clerbaux, Cathy

    2007-01-01

    Simultaneous ACE (Atmospheric Chemistry Experiment) upper tropospheric CO, C2H6, HCN, CH3Cl, CH4 , C2H2 , CH30H, HCOOH, and OCS measurements show plumes up to 185 ppbv (10 (exp -9) per unit volume) for CO, 1.36 ppbv for C2H6, 755 pptv (10(exp -12) per unit volume) for HCN, 1.12 ppbv for CH3C1, 1.82 ppmv, (10(exp -6) per unit volume) for CH4, 0.178 ppbv for C2H2, 3.89 ppbv for CH30H, 0.843 ppbv for HCOOH, and 0.48 ppbv for OCS in western Canada and Alaska at 50 deg N-68 deg N latitude between 29 June and 23 July 2004. Enhancement ratios and emission factors for HCOOH, CH30H, HCN, C2H6, and OCS relative to CO at 250-350 hPa are inferred from measurements of young plumes compared with lower mixing ratios assumed to represent background conditions based on a CO emission factor derived from boreal measurements. Results are generally consistent with the limited data reported for various vegetative types and emission phases measured in extratropical forests including boreal forests. The low correlation between fire product emission mixing ratios and the S176 mixing ratio is consistent with no significant SF6 emissions from the biomass fires.

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Widespread HCN maser emission in carbon-rich evolved stars

    NASA Astrophysics Data System (ADS)

    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 = 21 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 = 21 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

  6. Association Reactions at Low Pressure: 5. The CH(sub 3)+/HCN System. A Final Word?

    NASA Technical Reports Server (NTRS)

    Anicich, V.; Sen, A.; Huntress, W.; McEwan, M.

    1994-01-01

    The reaction of the methyl cation with hydrogen cyanide is revisited. We have confidence that we have resolved a long standing apparent contradiction of experimental results. A literature history is presented along with one new experiment and a reexamination of an old experiment. In this present work it is shown that all of the previous studies had made consistent observations. Yet, each of the previous studies failed to observe all of the information present. The methyl cation does react with HCN by radiative association, a fact which had been in doubt. The product ions formed in the two-body and three-body processes react differently with HCN. The collisionally stabilized association product formed by a three-body mechanism does not react with HCN and is readily detected in the experiments. The radiatively stabilized association product, formed by a slow two-body reaction, is not detected because it reacts with HCN by a fast proton transfer reaction forming the protonated HCN ion.

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

    PubMed Central

    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

  8. A search for SiO, OH, CO and HCN radio emission from silicate-carbon stars

    NASA Technical Reports Server (NTRS)

    Little-Marenin, I. R.; Sahai, R.; Wannier, P. G.; Benson, P. J.; Gaylard, M.; Omont, A.

    1994-01-01

    We report upper limits for radio emission of SiO at 86 and 43 GHz, of OH at 1612 and 1665/1667 MHz, of CO at 115 GHz and HCN at 88.6 GHz in the silicate-carbon stars. These upper limits of SiO imply that oxygen-rich material has not been detected within 2R(sub star) of a central star even though the detected emission from silicate dust grains, H2O and OH maser establishes the presence of oxygen-rich material from about tens to thousands of AU of a central star. The upper limit of the SiO abundance is consistent with that found in oxygen-rich envelopes. Upper limits of the mass loss rate (based on the CO data) are estimated to be between 10(exp -6) to 10(exp -7) solar mass/yr assuming a distance of 1.5 kpc for these stars. The absence of HCN microwave emission implies that no carbon-rich material can be detected at large distances (thousands of AU) from a central star. The lack of detections of SiO, CO, and HCN emission is most likely due to the large distances of these stars. A number of C stars were detected in CO and HCN, but only the M supergiant VX Sgr was detected in CO.

  9. Endogenous channels in HEK cells and potential roles in HCN ionic current measurements.

    PubMed

    Varghese, Anthony; Tenbroek, Erica M; Coles, James; Sigg, Daniel C

    2006-01-01

    A transformed line of human embryonic kidney epithelial cells (HEK 293) is commonly used as an expression system for exogenous ion channel genes. Previously, it has been shown that these cells contain mRNAs for a variety of ion channels. Expression of some of these genes has been confirmed at the protein level. Patch-clamp electrophysiology experiments confirm the presence of multiple ion channels and molecular data agree with pharmacological profiles of identified channels. In this work, we show that endogenous voltage-gated potassium channels in HEK cells are a significant source of outward current at positive potentials. We show that both non-transfected HEK cells and HEK cells transfected with hyperpolarization-activated cyclic-nucleotide gated (HCN) channels have a significant amount of voltage-gated potassium (K(V)) current when certain tail current voltage-clamp protocols are used to assay HCN current activation. Specifically, tail current protocols that use a depolarized holding potential of -40 mV followed by hyperpolarizing pulses (-80 to -140 mV) and then a tail pulse potential of +20 mV indicate K(V) channels undergo closed-state inactivation at the more depolarized holding potential of -40 mV, followed by recovery from inactivation (but no activation) at hyperpolarizing potentials and high amount of activation at the positive tail potential. Our results indicate that pulse protocols with positive tail pulses are inaccurate assays for HCN current in certain HEK cells. Surprisingly, HEK-293 cells were found to contain mRNA for HCN2 and HCN3 although we have not detected a significant and consistent endogenous I(f)-like current in these cells.

  10. A novel 'splice site' HCN4 Gene mutation, c.1737+1 G>T, causes familial bradycardia, reduced heart rate response, impaired chronotropic competence and increased short-term heart rate variability.

    PubMed

    Hategan, Lidia; Csányi, Beáta; Ördög, Balázs; Kákonyi, Kornél; Tringer, Annamária; Kiss, Orsolya; Orosz, Andrea; Sághy, László; Nagy, István; Hegedűs, Zoltán; Rudas, László; Széll, Márta; Varró, András; Forster, Tamás; Sepp, Róbert

    2017-08-15

    The most important molecular determinant of heart rate regulation in sino-atrial pacemaker cells includes hyperpolarization-activated, cyclic nucleotide-gated ion channels, the major isoform of which is encoded by the HCN4 gene. Mutations affecting the HCN4 gene are associated primarily with sick sinus syndrome. A novel c.1737+1 G>T 'splice-site' HCN4 mutation was identified in a large family with familial bradycardia which co-segregated with the disease providing a two-point LOD score of 4.87. Twelve out of the 22 investigated family members [4 males, 8 females average age 36 (SD 6) years] were considered as clinically affected (heart rate<60/min on resting ECG). Minimum [36 (SD 7) vs. 47 (SD 5) bpm, p=0.0087) and average heart rates [62 (SD 8) vs. 73 (SD 8) bpm, p=0.0168) were significantly lower in carriers on 24-hour Holter recordings. Under maximum exercise test carriers achieved significantly lower heart rates than non-carrier family members, and percent heart rate reserve and percent corrected heart rate reserve were significantly lower in carriers. Applying rigorous criteria for chronotropic incompetence a higher number of carriers exhibited chronotropic incompetence. Parameters, characterizing short-term variability of heart rate (i.e. rMSSD and pNN50%) were increased in carrier family members, even after normalization for heart rate, in the 24-hour ECG recordings with the same relative increase in 5-minute recordings. The identified novel 'splice site' HCN4 gene mutation, c.1737+1 G>T, causes familial bradycardia and leads to reduced heart rate response, impaired chronotropic competence and increased short-term heart rate variability in the mutation carriers. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Retrieval of haze properties and HCN concentrations from the three-micron spectrum of Titan

    NASA Astrophysics Data System (ADS)

    Kim, Sang J.; Lee, D. W.; Sim, C. K.; Seon, K. I.; Courtin, R.; Geballe, T. R.

    2018-05-01

    The 3 μm spectrum of Titan contains line emission and absorption as well as a significant haze continuum. The line emission has been previously analyzed in the literature, but that analysis has not properly included the influence of haze on the line emission. We report a new analysis of the 3 μm HCN emission spectrum using radiative transfer equations that include scattering and absorption by molecules and haze particles at altitudes lower than 500 km, where the influence of haze on the emergent spectrum becomes significant. Taking advantage of the dominance of resonant single scattering in the HCN ν3 fundamental and of the moderate haze optical thickness of the atmosphere around 3 μm, we adopt single dust and molecular scattering and present a formulation for the radiative transfer process. We evaluate the quantitative influence of haze scattering on the emission line intensities, and derive vertically-resolved single scattering albedos of the haze from model fits. We also present the resulting concentrations of HCN for altitudes below 500 km, where we find that the haze scattering significantly influences the retrieval of the concentrations of HCN. We conclude that the formulation we present is useful for the analysis of the HCN line emission from Titan and other similar hazy planetary or celestial objects.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cui, J.; Cao, Y.-T.; Lavvas, P. P.

    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 volumemore » 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.« less

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

    PubMed Central

    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

  14. Theoretical study of photoacidity of HCN: the effect of complexation with water.

    PubMed

    Muchová, Eva; Spirko, Vladimir; Hobza, Pavel; Nachtigallová, Dana

    2006-11-14

    The character of the hydrogen bonding and the excited state proton transfer (ESPT) in the model system HCN...H(2)O is investigated. The PES of the two lowest excited states of the H(2)O...HCN complex was calculated using the CASPT2 method. The nonadiabatic coupling of the two states of the (pi-->pi*) and (pi-->sigma*) character is responsible for the excited state proton/hydrogen transfer. Compared to the ground state, the barrier for this process is significantly smaller. An increased number of water molecules in the complex with cyclic hydrogen-bonded network causes a large blue shift of the state of the (pi-->sigma*) character. The question of the dissociation of the complex in its excited state is also addressed.

  15. Distribution and Kinematics of the HCN (3-2) Emission Down to the Innermost Region in the Envelope of the O-rich Star W Hydrae

    NASA Astrophysics Data System (ADS)

    Muller, Sébastien; Dinh-V-Trung; He, Jin-Hua; Lim, Jeremy

    2008-09-01

    We report high angular resolution observations of the HCN (3-2) line emission in the circumstellar envelope of the O-rich star W Hya with the Submillimeter Array. The proximity of this star allows us to image its molecular envelope with a spatial resolution of just ~40 AU, corresponding to about 10 times the stellar diameter. We resolve the HCN (3-2) emission and find that it is centrally peaked and has a roughly spherically symmetrical distribution. This shows that HCN is formed in the innermost region of the envelope (within ~10 stellar radii), which is consistent with predictions from pulsation-driven shock chemistry models, and rules out the scenario in which HCN forms through photochemical reactions in the outer envelope. Our model suggests that the envelope decreases steeply in temperature and increases smoothly in velocity with radius, inconsistent with the standard model for mass-loss driven by radiative pressure on dust grains. We detect a velocity gradient of ~5 km s-1 in the northwest-southeast direction over the central 40 AU. This velocity gradient is reminiscent of that seen in OH maser lines, and could be caused by the rotation of the envelope or by a weak bipolar outflow.

  16. Clay-mediated reactions of HCN oligomers - The effect of the oxidation state of the clay

    NASA Technical Reports Server (NTRS)

    Ferris, J. P.; Alwis, K. W.; Edelson, E. H.; Mount, N.; Hagan, W. J., Jr.

    1981-01-01

    Montmorillonite clays which contain Fe(III) inhibit the oligomerization of aqueous solutions of HCN. The inhibitory effect is due to the rapid oxidation of diaminomaleonitrile, a key intermediate in HCN oligomerization, by the Fe(III) incorporated into the aluminosilicate lattice of the clay. The Fe(III) oxidizes diaminomaleonitrile to diiminosuccinonitrile, a compound which is rapidly hydrolyzed to HCN and oxalic acid derivatives. Diaminomaleonitrile is not oxidized when Fe(III) in the montmorillonite is reduced with hydrazine. The oxidation state of the clay is an important variable in experiments designed to simulate clay catalysis on the primitive earth.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Thermal formation of hydroxynitriles, precursors of hydroxyacids in astrophysical ice analogs: Acetone ((CH3)2Cdbnd O) and hydrogen cyanide (HCN) reactivity

    NASA Astrophysics Data System (ADS)

    Fresneau, Aurélien; Danger, Grégoire; Rimola, Albert; Duvernay, Fabrice; Theulé, Patrice; Chiavassa, Thierry

    2015-11-01

    Reactivity in astrophysical environments is still poorly understood. In this contribution, we investigate the thermal reactivity of interstellar ice analogs containing acetone ((CH3)2CO), ammonia (NH3), hydrogen cyanide (HCN) and water (H2O) by means of infrared spectroscopy and mass spectrometry techniques, complemented by quantum chemical calculations. We show that no reaction occurs in H2O:HCN:(CH3)2CO ices. Nevertheless, HCN does indeed react with acetone once activated by NH3 into CN- to form 2-hydroxy-2-methylpropanenitrile (HOsbnd C(CH3)2sbnd CN), with a calculated activation energy associated with the rate determining step of about 51 kJ mol-1. This reaction inhibits the formation of 2-aminopropan-2-ol (HOsbnd C(CH3)2sbnd NH2) from acetone and NH3, even in the presence of water, which is the first step of the Strecker synthesis to form 2-aminoisobutyric acid (NH2C(CH3)2COOH). However, HOsbnd C(CH3)2sbnd CN formation could be part of an alternative chemical pathway leading to 2-hydroxy-2-methyl-propanoic acid (HOC(CH3)2COOH), which could explain the presence of hydroxy acids in some meteorites.

  20. The MALATANG Survey: The L GAS–L IR Correlation on Sub-kiloparsec Scale in Six Nearby Star-forming Galaxies as Traced by HCN J = 4 → 3 and HCO+ J = 4 → 3

    NASA Astrophysics Data System (ADS)

    Tan, Qing-Hua; Gao, Yu; Zhang, Zhi-Yu; Greve, Thomas R.; Jiang, Xue-Jian; Wilson, Christine D.; Yang, Chen-Tao; Bemis, Ashley; Chung, Aeree; Matsushita, Satoki; Shi, Yong; Ao, Yi-Ping; Brinks, Elias; Currie, Malcolm J.; Davis, Timothy A.; de Grijs, Richard; Ho, Luis C.; Imanishi, Masatoshi; Kohno, Kotaro; Lee, Bumhyun; Parsons, Harriet; Rawlings, Mark G.; Rigopoulou, Dimitra; Rosolowsky, Erik; Bulger, Joanna; Chen, Hao; Chapman, Scott C.; Eden, David; Gear, Walter K.; Gu, Qiu-Sheng; He, Jin-Hua; Jiao, Qian; Liu, Dai-Zhong; Liu, Li-Jie; Li, Xiao-Hu; Michałowski, Michał J.; Nguyen-Luong, Quang; Qiu, Jian-Jie; Smith, Matthew W. L.; Violino, Giulio; Wang, Jian-Fa; Wang, Jun-Feng; Wang, Jun-Zhi; Yeh, Sherry; Zhao, Ying-He; Zhu, Ming

    2018-06-01

    We present {HCN} J=4\\to 3 and {HCO}}+ J=4\\to 3 maps of six nearby star-forming galaxies, NGC 253, NGC 1068, IC 342, M82, M83, and NGC 6946, obtained with the James Clerk Maxwell Telescope as part of the MALATANG survey. All galaxies were mapped in the central 2‧ × 2‧ region at 14″ (FWHM) resolution (corresponding to linear scales of ∼0.21.0 kpc). The L IR–L‧dense relation, where the dense gas is traced by the {HCN} J=4\\to 3 and the {HCO}}+ J=4\\to 3 emission, measured in our sample of spatially resolved galaxies is found to follow the linear correlation established globally in galaxies within the scatter. We find that the luminosity ratio, L IR/L‧dense, shows systematic variations with L IR within individual spatially resolved galaxies, whereas the galaxy-integrated ratios vary little. A rising trend is also found between L IR/L‧dense ratio and the warm-dust temperature gauged by the 70 μm/100 μm flux ratio. We find that the luminosity ratios of IR/HCN (4–3) and IR/HCO+ (4–3), which can be taken as a proxy for the star formation efficiency (SFE) in the dense molecular gas (SFEdense), appear to be nearly independent of the dense gas fraction (f dense) for our sample of galaxies. The SFE of the total molecular gas (SFEmol) is found to increase substantially with f dense when combining our data with those on local (ultra)luminous infrared galaxies and high-z quasars. The mean L{{\\prime} }HCN(4{--}3)}/L{{\\prime} }HCO}+(4{--}3)} line ratio measured for the six targeted galaxies is 0.9 ± 0.6. No significant correlation is found for the L{{\\prime} }HCN(4{--}3)}/L{{\\prime} }HCO}+(4{--}3)} ratio with the star formation rate as traced by L IR, nor with the warm-dust temperature, for the different populations of galaxies.

  1. Role of Dynamics in the Autoinhibition and Activation of the Hyperpolarization-activated Cyclic Nucleotide-modulated (HCN) Ion Channels*♦

    PubMed Central

    VanSchouwen, Bryan; Akimoto, Madoka; Sayadi, Maryam; Fogolari, Federico; Melacini, Giuseppe

    2015-01-01

    The hyperpolarization-activated cyclic nucleotide-modulated (HCN) ion channels control rhythmicity in neurons and cardiomyocytes. Cyclic AMP allosterically modulates HCN through the cAMP-dependent formation of a tetrameric gating ring spanning the intracellular region (IR) of HCN, to which cAMP binds. Although the apo versus holo conformational changes of the cAMP-binding domain (CBD) have been previously mapped, only limited information is currently available on the HCN IR dynamics, which have been hypothesized to play a critical role in the cAMP-dependent gating of HCN. Here, using molecular dynamics simulations validated and complemented by experimental NMR and CD data, we comparatively analyze HCN IR dynamics in the four states of the thermodynamic cycle arising from the coupling between cAMP binding and tetramerization equilibria. This extensive set of molecular dynamics trajectories captures the active-to-inactive transition that had remained elusive for other CBDs, and it provides unprecedented insight on the role of IR dynamics in HCN autoinhibition and its release by cAMP. Specifically, the IR tetramerization domain becomes more flexible in the monomeric states, removing steric clashes that the apo-CDB structure would otherwise impose. Furthermore, the simulations reveal that the active/inactive structural transition for the apo-monomeric CBD occurs through a manifold of pathways that are more divergent than previously anticipated. Upon cAMP binding, these pathways become disallowed, pre-confining the CBD conformational ensemble to a tetramer-compatible state. This conformational confinement primes the IR for tetramerization and thus provides a model of how cAMP controls HCN channel gating. PMID:25944904

  2. ALMA Imaging of HCN, CS, and Dust in Arp 220 and NGC 6240

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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 × 109 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 nH_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 × 105 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.

  3. Coupling catalytic hydrolysis and oxidation of HCN over HZSM-5 modified by metal (Fe,Cu) oxides

    NASA Astrophysics Data System (ADS)

    Hu, Yanan; Liu, Jiangping; Cheng, Jinhuan; Wang, Langlang; Tao, Lei; Wang, Qi; Wang, Xueqian; Ning, Ping

    2018-01-01

    In this work, a series of metal oxides (Fe,Cu) modified HZSM-5 catalysts were synthesized by incipient-wetness impregnation method and then characterized by XRD, N2 adsorption-desorption, H2-TPR, NH3-TPD, UV-vis, FT-IR and XPS measurements. The catalytic hydrolysis and oxidation behaviors toward HCN were investigated. The results indicated that the Fe-Cu/HZSM-5 catalysts exhibited more excellent performence on coupling catalytic hydrolysis and oxidation of HCN than HZSM-5, Fe/HZSM-5, Cu/HZSM-5, and both nearly 100% HCN conversion and 80% N2 selectivity were obtained at about 250 °C. The improved catalytic performance could be ascribed to the creation of highly dispersed iron and copper composites on the surface of the HZSM-5 support, the excellent redox and regulated acid properties of the active ingredients. Moreover, the highly N2 selectivity could be attributed to the good interaction between the Fe and Cu nanocomposites which was facilitated to the NH3-SCR (selective catalytic reduction of NO by NH3) reaction.

  4. HCN and CN in comet 2P/Encke, a three-dimensional view on comet Encke's outgassing

    NASA Astrophysics Data System (ADS)

    Jockers, K.; Szutowicz, S.

    2008-09-01

    on the nucleus surface were identified, one at latitude +55° (source I) and another one at latitude -75° (source II). The derivation is based on the incorrect assumption that the fan consists of dust particles. Therefore the location of the active vents may be erroneous but the pole location is reliable. Observations The observations were performed in November 2003. The 4-3 (354.505475 GHz) and 3-2 (265.886436 GHz) transitions of HCN were observed in Comet Encke at the 10m Heinrich-Hertz-Telescope of Steward Observatory and MPI for Radio Astronomy with the heterodyne spectrometer of the MPI for Solar System Science (MPS) during Nov. 18-30 by G. Villanueva and S. Szutowicz. For the optical observations the 2m-telescope of the Institute of Astronomy of the Bulgarian Acad. Sci. was used with the Two-Channel Focal Reducer developed and built at the MPS. 16 images were taken by K. Jockers, T. Bonev, and G. Borisov in the CN 0-0 B 2?+ ! X 2?+ band at 388 nm. The observations were performed on the inward branch of the cometary orbit. The heliocentric distance varied from 0.98 to 0.77 AU and the solar phase angle from 83° to 123°. In this presentation the data are compared with Monte Carlo particle trajectory models for both species, HCN and CN. Parent and daughter life times: The CN pictures of the comet were averaged in azimuth in a circular area around the comet with approximate radius of 26,000 km to derive the parent life time. In accordance with the radio data the cometary outflow velocity is assumed 1.1 km s-1 and the daughter velocity received at photodissociation of the parent is 0.864 km/s [4]. The Solar2000 space weather solar irradiation model (Kent Tobiska, SpaceWx.com) was applied to the laboratory data [5] to yield CN lifetimes for the time of observations. They are in the range of it 2.2 ·105 s when referred to 1 AU. The model of [6] was applied to the CN observations and the parent life time was determined. When scaled to 1 AU it is in the range of 15

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chenel, Aurelie; Roncero, Octavio, E-mail: octavio.roncero@csic.es; Aguado, Alfredo

    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, hereaftermore » 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.« less

  6. A SIFT ion-molecule study of some reactions in Titan's atmosphere. reactions of N(+), N(2)(+), and HCN(+) with CH(4), C(2)H(2), and C(2)H(4)

    NASA Technical Reports Server (NTRS)

    Anicich, Vincent G.; Wilson, Paul; McEwan, Murray J.

    2004-01-01

    The results of a study of the ion-molecule reactions of N(+), N(2)(+), and HCN(+) with methane, acetylene, and ethylene are reported. These studies were performed using the FA-SIFT at the University of Canterbury. The reactions studied here are important to understanding the ion chemistry in Titan's atmosphere. N(+) and N(2)(+) are the primary ions formed by photo-ionization and electron impact in Titan's ionosphere and drive Titan's ion chemistry. It is therefore very important to know how these ions react with the principal trace neutral species in Titan's atmosphere: Methane, acetylene, and ethylene. While these reactions have been studied before the product channels have been difficult to define as several potential isobaric products make a definitive answer difficult. Mass overlap causes difficulties in making unambiguous species assignments in these systems. Two discriminators have been used in this study to resolve the mass overlap problem. They are deuterium labeling and also the differences in reactivities of each isobar with various neutral reactants. Several differences have been found from the products in previous work. The HCN(+) ion is important in both Titan's atmosphere and in the laboratory.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Scoville, Nick; Manohar, Swarnima; Murchikova, Lena

    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 dustmore » 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.« less

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

    NASA Astrophysics Data System (ADS)

    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.

  9. DEVELOPMENT OF A MONITOR FOR HCN IN MOBILE SOURCE EMISSIONS

    EPA Science Inventory

    Three real-time monitors for measurement of HCN concentrations in mobile source emissions have been designed, built, tested, and delivered to the Environmental Protection Agency (EPA). The important design parameters for these identical instruments were determined during the firs...

  10. The KCNE Tango – How KCNE1 Interacts with Kv7.1

    PubMed Central

    Wrobel, Eva; Tapken, Daniel; Seebohm, Guiscard

    2012-01-01

    The classical tango is a dance characterized by a 2/4 or 4/4 rhythm in which the partners dance in a coordinated way, allowing dynamic contact. There is a surprising similarity between the tango and how KCNE β-subunits “dance” to the fast rhythm of the cell with their partners from the Kv channel family. The five KCNE β-subunits interact with several members of the Kv channels, thereby modifying channel gating via the interaction of their single transmembrane-spanning segment, the extracellular amino terminus, and/or the intracellular carboxy terminus with the Kv α-subunit. Best studied is the molecular basis of interactions between KCNE1 and Kv7.1, which, together, supposedly form the native cardiac IKs channel. Here we review the current knowledge about functional and molecular interactions of KCNE1 with Kv7.1 and try to summarize and interpret the tango of the KCNEs. PMID:22876232

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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 < 0.05; P < 0.01, respectively) in neuroblastoma tissue, whereas MEG3 displayed the lower expression (P < 0.01). HIF-1α expression was negatively correlated with cell proliferation in the linc01105 KD group. In addition, Noxa and Bid expression was positively correlated with cell apoptosis. Moreover, linc01105 knockdown promoted cell proliferation, whereas MEG3 overexpression inhibited proliferation. Finally, linc01105 knockdown, MEG3 overexpression and HCN3 knockdown all increased apoptosis. The correlation coefficients between those three lncRNAs and the International Neuroblastoma Staging System (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.

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

    PubMed Central

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

    2016-01-01

    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 < 0.05; P < 0.01, respectively) in neuroblastoma tissue, whereas MEG3 displayed the lower expression (P < 0.01). HIF-1α expression was negatively correlated with cell proliferation in the linc01105 KD group. In addition, Noxa and Bid expression was positively correlated with cell apoptosis. Moreover, linc01105 knockdown promoted cell proliferation, whereas MEG3 overexpression inhibited proliferation. Finally, linc01105 knockdown, MEG3 overexpression and HCN3 knockdown all increased apoptosis. The correlation coefficients between those three lncRNAs and the International Neuroblastoma Staging System (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. PMID:27824082

  14. KCNE4 and KCNE5: K+ channel regulation and cardiac arrhythmogenesis

    PubMed Central

    Abbott, Geoffrey W.

    2016-01-01

    KCNE proteins are single transmembrane-segment voltage-gated potassium (Kv) channel ancillary subunits that exhibit a diverse range of physiological functions. Human KCNE gene mutations are associated with various pathophysiological states, most notably cardiac arrhythmias. Of the five isoforms in the human KCNE gene family, KCNE4 and the X-linked KCNE5 are, to date, the least-studied. Recently, however, interest in these neglected genes has been stoked by their putative association with debilitating or lethal cardiac arrhythmias. The sometimes-overlapping functional effects of KCNE4 and KCNE5 vary depending on both their Kv α subunit partner and on other ancillary subunits within the channel complex, but mostly fall into two contrasting categories either inhibition, or fine-tuning of gating kinetics. This review covers current knowledge regarding the molecular mechanisms of KCNE4 and KCNE5 function, human disease associations, and findings from very recent studies of cardiovascular pathophysiology in Kcne4−/− mice. PMID:27484720

  15. KCNE4 and KCNE5: K(+) channel regulation and cardiac arrhythmogenesis.

    PubMed

    Abbott, Geoffrey W

    2016-11-30

    KCNE proteins are single transmembrane-segment voltage-gated potassium (Kv) channel ancillary subunits that exhibit a diverse range of physiological functions. Human KCNE gene mutations are associated with various pathophysiological states, most notably cardiac arrhythmias. Of the five isoforms in the human KCNE gene family, KCNE4 and the X-linked KCNE5 are, to date, the least-studied. Recently, however, interest in these neglected genes has been stoked by their putative association with debilitating or lethal cardiac arrhythmias. The sometimes-overlapping functional effects of KCNE4 and KCNE5 vary depending on both their Kv α subunit partner and on other ancillary subunits within the channel complex, but mostly fall into two contrasting categories - either inhibition, or fine-tuning of gating kinetics. This review covers current knowledge regarding the molecular mechanisms of KCNE4 and KCNE5 function, human disease associations, and findings from very recent studies of cardiovascular pathophysiology in Kcne4(-/-) mice. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Predictions of the Contribution of HCN Half-Maximal Activation Potential Heterogeneity to Variability in Intrinsic Adaptation of Spiral Ganglion Neurons.

    PubMed

    Boulet, Jason; Bruce, Ian C

    2017-04-01

    Spiral ganglion neurons (SGNs) exhibit a wide range in their strength of intrinsic adaptation on a timescale of 10s to 100s of milliseconds in response to electrical stimulation from a cochlear implant (CI). The purpose of this study was to determine how much of that variability could be caused by the heterogeneity in half-maximal activation potentials of hyperpolarization-activated cyclic nucleotide-gated cation (HCN) channels, which are known to produce intrinsic adaptation. In this study, a computational membrane model of cat type I SGN was developed based on the Hodgkin-Huxley model plus HCN and low-threshold potassium (KLT) conductances in which the half-maximal activation potential of the HCN channel was varied and the response of the SGN to pulse train and paired-pulse stimulation was simulated. Physiologically plausible variation of HCN half-maximal activation potentials could indeed determine the range of adaptation on the timescale of 10s to 100s of milliseconds and recovery from adaptation seen in the physiological data while maintaining refractoriness within physiological bounds. This computational model demonstrates that HCN channels may play an important role in regulating the degree of adaptation in response to pulse train stimulation and therefore contribute to variable constraints on acoustic information coding by CIs. This finding has broad implications for CI stimulation paradigms in that cell-to-cell variation of HCN channel properties are likely to significantly alter SGN excitability and therefore auditory perception.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Daniels, R.C.; Boden, T.A.; Easterling, D.R.

    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 beenmore » 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.« less

  18. Molecular Reconnaissance of the β Pictoris Gas Disk with the SMA: A Low HCN/(CO+CO2) Outgassing Ratio and Predictions for Future Surveys

    NASA Astrophysics Data System (ADS)

    Matrà, L.; Wilner, D. J.; Öberg, K. I.; Andrews, S. M.; Loomis, R. A.; Wyatt, M. C.; Dent, W. R. F.

    2018-02-01

    The exocometary origin of CO gas has been confirmed in several extrasolar Kuiper belts, with CO ice abundances consistent with solar system comets. We here present a molecular survey of the β Pictoris belt with the Submillimeter Array (SMA), reporting upper limits for CN, HCN, HCO+, N2H+, and H2CO, as well as for H2S, CH3OH, SiO, and DCN from archival ALMA data. Nondetections can be attributed to rapid molecular photodissociation due to the A-star’s strong UV flux. CN is the longest lasting and most easily detectable molecule after CO in this environment. We update our nonlocal thermodynamic equilibrium excitation model to include UV fluorescence, finding it plays a key role in CO and CN excitation, and we use it to turn the SMA CN/CO flux ratio constraint into an upper limit of < 2.5% on the HCN/(CO+CO2) ratio of outgassing rates. This value is consistent with, but at the low end of, the broad range observed in solar system comets. If sublimation dominates outgassing, then this low value may be caused by decreased outgassing for the less volatile molecule HCN compared to CO. If instead UV photodesorption or collisional vaporization of unbound grains dominates outgassing, then this low ratio of rates would imply a low ice abundance ratio, which would in turn indicate a variation in cometary cyanide abundances across planetary systems. To conclude, we make predictions for future molecular surveys and show that CN and HCN should be readily detectable with ALMA around β Pictoris for solar-system-like exocometary compositions.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Denis-Alpizar, Otoniel, E-mail: otonieldenisalpizar@gmail.com; Departamento de Física, Universidad de Matanzas, Matanzas 40100; Kalugina, Yulia

    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}more » 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.« less

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

    NASA Astrophysics Data System (ADS)

    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

  1. 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

    NASA Technical Reports Server (NTRS)

    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.

  2. Structural Basis of Tonic Inhibition by Dimers of Dimers in Hyperpolarization-Activated Cyclic-Nucleotide-Modulated (HCN) Ion Channels.

    PubMed

    VanSchouwen, Bryan; Melacini, Giuseppe

    2016-10-03

    The hyperpolarization-activated cyclic-nucleotide-modulated (HCN) ion channels control rhythmicity in neurons and cardiomyocytes. Cyclic AMP (cAMP) modulates HCN activity through cAMP-dependent formation of a tetrameric gating ring spanning the intracellular region (IR) of HCN. In the absence of cAMP, the IR cAMP-binding domain (CBD) mainly samples its inactive conformation, resulting in steric clashes that destabilize the IR tetramer. Although these clashes with the inactive CBD are released through tetramer dissociation into monomers, functional mutagenesis suggests that the apo IR is not fully monomeric. To investigate the inhibitory non-monomeric IR species, we performed molecular dynamics simulations starting from "hybrid" structures that are tetrameric, but contain inactive apo-state CBD conformations. The ensemble of simulated trajectories reveals that full dissociation of the tetramer into monomers is not necessary to release the steric hindrance with the inactive CBD. Specifically, we found that partial dissociation of the tetramer into dimers is sufficient to accommodate four inactive CBDs, while reduction of the quaternary symmetry of the non-dissociated tetramer from four- to two-fold permits accommodation of two inactive CBDs. Our findings not only rationalize available electrophysiological, fluorometry and sedimentation equilibrium data, but they also provide unprecedented structural insight into previously elusive non-monomeric auto-inhibitory HCN species.

  3. The KCNQ1-KCNE2 K+ channel is required for adequate thyroid I− uptake

    PubMed Central

    Purtell, Kerry; Paroder-Belenitsky, Monika; Reyna-Neyra, Andrea; Nicola, Juan P.; Koba, Wade; Fine, Eugene; Carrasco, Nancy; Abbott, Geoffrey W.

    2012-01-01

    The KCNQ1 α subunit and the KCNE2 β subunit form a potassium channel in thyroid epithelial cells. Genetic disruption of KCNQ1-KCNE2 causes hypothyroidism in mice, resulting in cardiac hypertrophy, dwarfism, alopecia, and prenatal mortality. Here, we investigated the mechanistic requirement for KCNQ1-KCNE2 in thyroid hormone biosynthesis, utilizing whole-animal dynamic positron emission tomography. The KCNQ1-specific antagonist (−)-[3R,4S]-chromanol 293B (C293B) significantly impaired thyroid cell I− uptake, which is mediated by the Na+/I− symporter (NIS), in vivo (dSUV/dt: vehicle, 0.028±0.004 min−1; 10 mg/kg C293B, 0.009±0.006 min−1) and in vitro (EC50: 99±10 μM C293B). Na+-dependent nicotinate uptake by SMCT, however, was unaffected. Kcne2 deletion did not alter the balance of free vs. thyroglobulin-bound I− in the thyroid (distinguished using ClO4−, a competitive inhibitor of NIS), indicating that KCNQ1-KCNE2 is not required for Duox/TPO-mediated I− organification. However, Kcne2 deletion doubled the rate of free I− efflux from the thyroid following ClO4− injection, a NIS-independent process. Thus, KCNQ1-KCNE2 is necessary for adequate thyroid cell I− uptake, the most likely explanation being that it is prerequisite for adequate NIS activity.—Purtell, K., Paroder-Belenitsky, M., Reyna-Neyra, A., Nicola, J. P., Koba, W., Fine, E., Carrasco, N., Abbott, G. W. The KCNQ1-KCNE2 K+ channel is required for adequate thyroid I− uptake. PMID:22549510

  4. Noradrenaline Modulates the Membrane Potential and Holding Current of Medial Prefrontal Cortex Pyramidal Neurons via β1-Adrenergic Receptors and HCN Channels.

    PubMed

    Grzelka, Katarzyna; Kurowski, Przemysław; Gawlak, Maciej; Szulczyk, Paweł

    2017-01-01

    The medial prefrontal cortex (mPFC) receives dense noradrenergic projections from the locus coeruleus. Adrenergic innervation of mPFC pyramidal neurons plays an essential role in both physiology (control of memory formation, attention, working memory, and cognitive behavior) and pathophysiology (attention deficit hyperactivity disorder, posttraumatic stress disorder, cognitive deterioration after traumatic brain injury, behavioral changes related to addiction, Alzheimer's disease and depression). The aim of this study was to elucidate the mechanism responsible for adrenergic receptor-mediated control of the resting membrane potential in layer V mPFC pyramidal neurons. The membrane potential or holding current of synaptically isolated layer V mPFC pyramidal neurons was recorded in perforated-patch and classical whole-cell configurations in slices from young rats. Application of noradrenaline (NA), a neurotransmitter with affinity for all types of adrenergic receptors, evoked depolarization or inward current in the tested neurons irrespective of whether the recordings were performed in the perforated-patch or classical whole-cell configuration. The effect of noradrenaline depended on β 1 - and not α 1 - or α 2 -adrenergic receptor stimulation. Activation of β 1 -adrenergic receptors led to an increase in inward Na + current through hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which carry a mixed Na + /K + current. The protein kinase A- and C-, glycogen synthase kinase-3β- and tyrosine kinase-linked signaling pathways were not involved in the signal transduction between β 1 -adrenergic receptors and HCN channels. The transduction system operated in a membrane-delimited fashion and involved the βγ subunit of G-protein. Thus, noradrenaline controls the resting membrane potential and holding current in mPFC pyramidal neurons through β 1 -adrenergic receptors, which in turn activate HCN channels via a signaling pathway involving the

  5. Noradrenaline Modulates the Membrane Potential and Holding Current of Medial Prefrontal Cortex Pyramidal Neurons via β1-Adrenergic Receptors and HCN Channels

    PubMed Central

    Grzelka, Katarzyna; Kurowski, Przemysław; Gawlak, Maciej; Szulczyk, Paweł

    2017-01-01

    The medial prefrontal cortex (mPFC) receives dense noradrenergic projections from the locus coeruleus. Adrenergic innervation of mPFC pyramidal neurons plays an essential role in both physiology (control of memory formation, attention, working memory, and cognitive behavior) and pathophysiology (attention deficit hyperactivity disorder, posttraumatic stress disorder, cognitive deterioration after traumatic brain injury, behavioral changes related to addiction, Alzheimer’s disease and depression). The aim of this study was to elucidate the mechanism responsible for adrenergic receptor-mediated control of the resting membrane potential in layer V mPFC pyramidal neurons. The membrane potential or holding current of synaptically isolated layer V mPFC pyramidal neurons was recorded in perforated-patch and classical whole-cell configurations in slices from young rats. Application of noradrenaline (NA), a neurotransmitter with affinity for all types of adrenergic receptors, evoked depolarization or inward current in the tested neurons irrespective of whether the recordings were performed in the perforated-patch or classical whole-cell configuration. The effect of noradrenaline depended on β1- and not α1- or α2-adrenergic receptor stimulation. Activation of β1-adrenergic receptors led to an increase in inward Na+ current through hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which carry a mixed Na+/K+ current. The protein kinase A- and C-, glycogen synthase kinase-3β- and tyrosine kinase-linked signaling pathways were not involved in the signal transduction between β1-adrenergic receptors and HCN channels. The transduction system operated in a membrane-delimited fashion and involved the βγ subunit of G-protein. Thus, noradrenaline controls the resting membrane potential and holding current in mPFC pyramidal neurons through β1-adrenergic receptors, which in turn activate HCN channels via a signaling pathway involving the βγ subunit. PMID

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

    PubMed

    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.

  7. 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 Fires of 1997-1998. Revised

    NASA Technical Reports Server (NTRS)

    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.; hide

    1999-01-01

    High spectral resolution (0.003/ 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, (19.5 deg N, 155.6 deg W, 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 two 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 deg N and 45 deg 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 3 the strong El Nino warm phase of 1997-1998 are the likely source of the elevated emission products.

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

    PubMed

    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.

  9. Unnatural amino acid photo-crosslinking of the IKs channel complex demonstrates a KCNE1:KCNQ1 stoichiometry of up to 4:4

    PubMed Central

    Murray, Christopher I; Westhoff, Maartje; Eldstrom, Jodene; Thompson, Emely; Emes, Robert; Fedida, David

    2016-01-01

    Cardiac repolarization is determined in part by the slow delayed rectifier current (IKs), through the tetrameric voltage-gated ion channel, KCNQ1, and its β-subunit, KCNE1. The stoichiometry between α and β-subunits has been controversial with studies reporting either a strict 2 KCNE1:4 KCNQ1 or a variable ratio up to 4:4. We used IKs fusion proteins linking KCNE1 to one (EQ), two (EQQ) or four (EQQQQ) KCNQ1 subunits, to reproduce compulsory 4:4, 2:4 or 1:4 stoichiometries. Whole cell and single-channel recordings showed EQQ and EQQQQ to have increasingly hyperpolarized activation, reduced conductance, and shorter first latency of opening compared to EQ - all abolished by the addition of KCNE1. As well, using a UV-crosslinking unnatural amino acid in KCNE1, we found EQQQQ and EQQ crosslinking rates to be progressively slowed compared to KCNQ1, which demonstrates that no intrinsic mechanism limits the association of up to four β-subunits within the IKs complex. DOI: http://dx.doi.org/10.7554/eLife.11815.001 PMID:26802629

  10. HCN and CN in Comet 2P/Encke: Models of the non-isotropic, rotation-modulated coma and CN parent life time

    NASA Astrophysics Data System (ADS)

    Jockers, K.; Szutowicz, S.; Villanueva, G.; Bonev, T.; Hartogh, P.

    2011-09-01

    Axisymmetric models of the outgassing of a cometary nucleus have been constructed. Such models can be used to describe a nucleus with a single active region. The models may include a solar zenith angle dependence of the outgassing. They retrieve the outgassing flux at distances from the nucleus where collisions between molecules are unimportant, as function of the angle with respect to the outgassing axis. The observed emissions must be optically thin. Furthermore the models assume that the outflow speed at large distance from the nucleus does not depend on direction. The value of the outflow speed is retrieved. The models are applied to CN images and HCN spectra of Comet 2P/Encke, obtained nearly simultaneously in November 2003 with the 2 m optical telescope on Mount Rozhen, Bulgaria, and with the 10 m Heinrich Hertz Submillimeter Telescope on Mount Graham, Arizona, USA. According to Sekanina (1988), Astron. J. 95, 911-924, at that time a single outgassing source was active. Input parameters to the models like the rotation period of the nucleus and a small correction to Sekanina's rotation axis are determined from a simpler jet position angle model. The rotation is prograde with a sideric period of 11.056 ± 0.024 h, in agreement with literature values. The best fit model has an outflow speed of 0.95 ± 0.04 km s -1. The same value has been derived from the corkscrew appearing in the CN images. The location of the outgassing axis is at colatitude δa = 7.4° ± 2.9° and longitude λa = 235° ± 17° (a definition of zero longitude is provided). Comet Encke's outgassing corresponds approximately to the longitudinally averaged solar input on a spherical nucleus (i.e. very likely comes from deeper layers) but with some deficiency of outgassing at mid-latitudes and non-zero outgassing from the dark polar cap. The presence of gas flow from the dark polar cap is explained as evidence of gas flow across the terminator. The models rely mostly on the CN images. The HCN

  11. Phase-space reaction network on a multisaddle energy landscape: HCN isomerization.

    PubMed

    Li, Chun-Biu; Matsunaga, Yasuhiro; Toda, Mikito; Komatsuzaki, Tamiki

    2005-11-08

    By using the HCN/CNH isomerization reaction as an illustrative vehicle of chemical reactions on multisaddle energy landscapes, we give explicit visualizations of molecular motions associated with a straight-through reaction tube in the phase space inside which all reactive trajectories pass from one basin to another, with eliminating recrossing trajectories in the configuration space. This visualization provides us with a chemical intuition of how chemical species "walk along" the reaction-rate slope in the multidimensional phase space compared with the intrinsic reaction path in the configuration space. The distinct nonergodic features in the two different HCN and CNH wells can be easily demonstrated by a section of Poincare surface of section in those potential minima, which predicts in a priori the pattern of trajectories residing in the potential well. We elucidate the global phase-space structure which gives rise to the non-Markovian dynamics or the dynamical correlation of sequential multisaddle chemical reactions. The phase-space structure relevant to the controllability of the product state in chemical reactions is also discussed.

  12. Global bending quantum number and the absence of monodromy in the HCN{r_reversible}CNH molecule

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Efstathiou, K.; Sadovskii, D.A.; Joyeux, M.

    We introduce and analyze a model system based on a deformation of a spherical pendulum that can be used to reproduce large amplitude bending vibrations of flexible triatomic molecules with two stable linear equilibria. On the basis of our model and the recent vibrational potential [ J. Chem. Phys. 115, 3706 (2001) ], we analyze the HCN/CNH isomerizing molecule. We find that HCN/CNH has no monodromy and introduce the second global bending quantum number for this system at all energies where the potential is expected to work. We also show that LiNC/LiCN is a qualitatively different system with monodromy.

  13. Membrane potential oscillations are not essential for spontaneous firing generation in L4 Aβ-afferent neurons after L5-spinal nerve axotomy and are not mediated by HCN channels.

    PubMed

    Djouhri, L; Smith, T; Alotaibi, M; Weng, X

    2018-06-03

    What is the central question of this study? Is spontaneous activity (SA) in L4-DRG neurons induced by L5 spinal nerve axotomy is associated with membrane potentials oscillations in theses neurons, and are these membrane oscillations mediated by HCN channels? What is the main finding and its importance? Unlike injured L5 DRG neurons which have been shown to be incapable of firing spontaneously without membrane potentials oscillations, such membrane oscillations are not essential for SA generation in conducting "uninjured'' L4 neurons, and they are not mediated by HCN channels. These findings suggest that the underlying cellular mechanisms of SA in injured and "uninjured'' DRG neurons induced by spinal nerve injury are distinct. The underlying cellular and molecular mechanisms of peripheral neuropathic pain are not fully understood. However, preclinical studies using animal models of this debilitating condition suggest that it is driven partly by aberrant spontaneous activity (SA) in injured and uninjured dorsal root ganglion (DRG) neurons, and that SA in injured DRG neurons is triggered by subthreshold membrane potential oscillations (SMPOs). Here, using in vivo intracellular recording from control L4-DRG neurons, and ipsilateral L4-DRG neurons in female Wistar rats that had previously undergone L5-spinal nerve axotomy (SNA), we examined whether conducting 'uninjured' L4-DRG neurons in SNA rats exhibit SMPOs, and if so, whether such SMPOs are associated with SA in those L4-neurons, and whether they are mediated by hyperpolarization-activated cyclic nucleotide gated (HCN) channels. We found that 7-days after SNA: (a) none of control A- or C-fibre DRG neurons showed SMPOs or SA, but 50%, 43% and 0% of spontaneously active cutaneous L4 Aβ-low threshold mechanoreceptors, Aβ-nociceptors and C-nociceptors exhibited SMPOs respectively in SNA rats with established neuropathic pain behaviors, (b) neither SMPOs nor SA in L4 Aβ-neurons were suppressed by blocking HCN

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

    PubMed

    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.

  15. Cotton-Mouton polarimeter with HCN laser on CHS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Akiyama, T.; Kawahata, K.; Ito, Y.

    Polarimeters based on the Cotton-Mouton effect hold promise for electron density measurements. We have designed and installed a Cotton-Mouton polarimeter on the Compact Helical System. The Cotton-Mouton effect is measured as the phase difference between probe and reference beams. In this system, an interferometric measurement can be performed simultaneously with the same probe chord. The light source is a HCN laser (wavelength of 337 {mu}m). Digital complex demodulation is adopted for small phase analysis. The line averaged density evaluated from the polarimeter along a plasma center chord is almost consistent with that from the interferometer.

  16. Charge movement in gating-locked HCN channels reveals weak coupling of voltage sensors and gate.

    PubMed

    Ryu, Sujung; Yellen, Gary

    2012-11-01

    HCN (hyperpolarization-activated cyclic nucleotide gated) pacemaker channels have an architecture similar to that of voltage-gated K(+) channels, but they open with the opposite voltage dependence. HCN channels use essentially the same positively charged voltage sensors and intracellular activation gates as K(+) channels, but apparently these two components are coupled differently. In this study, we examine the energetics of coupling between the voltage sensor and the pore by using cysteine mutant channels for which low concentrations of Cd(2+) ions freeze the open-closed gating machinery but still allow the sensors to move. We were able to lock mutant channels either into open or into closed states by the application of Cd(2+) and measure the effect on voltage sensor movement. Cd(2+) did not immobilize the gating charge, as expected for strict coupling, but rather it produced shifts in the voltage dependence of voltage sensor charge movement, consistent with its effect of confining transitions to either closed or open states. From the magnitude of the Cd(2+)-induced shifts, we estimate that each voltage sensor produces a roughly three- to sevenfold effect on the open-closed equilibrium, corresponding to a coupling energy of ∼1.3-2 kT per sensor. Such coupling is not only opposite in sign to the coupling in K(+) channels, but also much weaker.

  17. KCNE1 remodels the voltage sensor of Kv7.1 to modulate channel function.

    PubMed

    Wu, Dick; Pan, Hua; Delaloye, Kelli; Cui, Jianmin

    2010-12-01

    The KCNE1 auxiliary subunit coassembles with the Kv7.1 channel and modulates its properties to generate the cardiac I(Ks) current. Recent biophysical evidence suggests that KCNE1 interacts with the voltage-sensing domain (VSD) of Kv7.1. To investigate the mechanism of how KCNE1 affects the VSD to alter the voltage dependence of channel activation, we perturbed the VSD of Kv7.1 by mutagenesis and chemical modification in the absence and presence of KCNE1. Mutagenesis of S4 in Kv7.1 indicates that basic residues in the N-terminal half (S4-N) and C-terminal half (S4-C) of S4 are important for stabilizing the resting and activated states of the channel, respectively. KCNE1 disrupts electrostatic interactions involving S4-C, specifically with the lower conserved glutamate in S2 (Glu(170) or E2). Likewise, Trp scanning of S4 shows that mutations to a cluster of residues in S4-C eliminate current in the presence of KCNE1. In addition, KCNE1 affects S4-N by enhancing MTS accessibility to the top of the VSD. Consistent with the structure of Kv channels and previous studies on the KCNE1-Kv7.1 interaction, these results suggest that KCNE1 alters the interactions of S4 residues with the surrounding protein environment, possibly by changing the protein packing around S4, thereby affecting the voltage dependence of Kv7.1. Copyright © 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Izumi, Takuma; Kohno, Kotaro; Aalto, Susanne

    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 themore » 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.« less

  19. 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

    NASA Technical Reports Server (NTRS)

    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.

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

    PubMed Central

    2009-01-01

    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. PMID:19849830

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

    PubMed

    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.

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

    PubMed

    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.

  3. Detection of CO and HCN in the coma of Jupiter-family comet 41P/Tuttle-Giacobini-Kresak

    NASA Astrophysics Data System (ADS)

    Wierzchos, Kacper; Womack, Maria

    2017-10-01

    Comets are divided into taxonomical groups determined largely by their orbits. Short-period Jupiter Family comets (JFCs) are thought to have formed in a trans-Neptunian disk ˜30 - 100 AU (Kuiper Belt) and then migrated inward (Edgeworth 1949, Kuiper 1951, Duncan et al. 1988). This different classification may be correlated with chemical abundance variations, and super-volatile species like CO can serve as an indicator of the thermal processes to which the precometary ices that led to comets where exposed (DiSainti et al. 2007). The close approach to Earth of comet 41P on the perihelion passage of 2017 was an excellent opportunity to probe the usually well-hidden inner coma of this Jupiter-family comet. We searched for CO (J=2-1) and HCN (J=3-2) emission with the Arizona Radio Observatory (ARO) 10-m Sub-millimeter Telescope (SMT) on 2017 April 1-2, when the comet was 1.1 AU from the Sun and 0.14 AU from Earth. We report the detection of both CO and HCN emission 13 days before perihelion and present column densities and production rates. We also discuss implications for Jupiter-family comets. The SMT is operated by the ARO, the Steward Observatory, and the University of Arizona, with support through the NSF University Radio Observatories program (AST-1140030). M.W. acknowledges support from NSF grant AST-1615917.

  4. KCNE1 divides the voltage sensor movement in KCNQ1/KCNE1 channels into two steps

    NASA Astrophysics Data System (ADS)

    Barro-Soria, Rene; Rebolledo, Santiago; Liin, Sara I.; Perez, Marta E.; Sampson, Kevin J.; Kass, Robert S.; Larsson, H. Peter

    2014-04-01

    The functional properties of KCNQ1 channels are highly dependent on associated KCNE-β subunits. Mutations in KCNQ1 or KCNE subunits can cause congenital channelopathies, such as deafness, cardiac arrhythmias and epilepsy. The mechanism by which KCNE1-β subunits slow the kinetics of KCNQ1 channels is a matter of current controversy. Here we show that KCNQ1/KCNE1 channel activation occurs in two steps: first, mutually independent voltage sensor movements in the four KCNQ1 subunits generate the main gating charge movement and underlie the initial delay in the activation time course of KCNQ1/KCNE1 currents. Second, a slower and concerted conformational change of all four voltage sensors and the gate, which opens the KCNQ1/KCNE1 channel. Our data show that KCNE1 divides the voltage sensor movement into two steps with widely different voltage dependences and kinetics. The two voltage sensor steps in KCNQ1/KCNE1 channels can be pharmacologically isolated and further separated by a disease-causing mutation.

  5. Kcne2 deletion uncovers its crucial role in thyroid hormone biosynthesis

    PubMed Central

    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 14% 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

  6. Boreal forest fire emissions in fresh Canadian smoke plumes: C1-C10 volatile organic compounds (VOCs), CO2, CO, NO2, NO, HCN and CH3CN

    NASA Astrophysics Data System (ADS)

    Simpson, I. J.; Akagi, S. K.; Barletta, B.; Blake, N. J.; Choi, Y.; Diskin, G. S.; Fried, A.; Fuelberg, H. E.; Meinardi, S.; Rowland, F. S.; Vay, S. A.; Weinheimer, A. J.; Wennberg, P. O.; Wiebring, P.; Wisthaler, A.; Yang, M.; Yokelson, R. J.; Blake, D. R.

    2011-03-01

    Boreal regions comprise about 17% of the global land area, and they both affect and are influenced by climate change. To better understand boreal forest fire emissions and plume evolution, 947 whole air samples were collected aboard the NASA DC-8 research aircraft in summer 2008 as part of the ARCTAS-B field mission, and analyzed for 79 non-methane volatile organic compounds (NMVOCs) using gas chromatography. Together with simultaneous measurements of CO2, CO, CH4, CH2O, NO2, NO, HCN and CH3CN, these measurements represent the most comprehensive assessment of trace gas emissions from boreal forest fires to date. Based on 105 air samples collected in fresh Canadian smoke plumes, 57 of the 80 measured NMVOCs (including CH2O) were emitted from the fires, including 45 species that were quantified from boreal forest fires for the first time. After CO2, CO and CH4, the largest emission factors (EFs) for individual species were formaldehyde (2.1 ± 0.2 g kg-1), followed by methanol, NO2, HCN, ethene, α-pinene, β-pinene, ethane, benzene, propene, acetone and CH3CN. Globally, we estimate that boreal forest fires release 2.4 ± 0.6 Tg C yr-1 in the form of NMVOCs, with approximately 41% of the carbon released as C1-C2 NMVOCs and 21% as pinenes. These are the first reported field measurements of monoterpene emissions from boreal forest fires, and we speculate that the pinenes, which are relatively heavy molecules, were detected in the fire plumes as the result of distillation of stored terpenes as the vegetation is heated. Their inclusion in smoke chemistry models is expected to improve model predictions of secondary organic aerosol (SOA) formation. The fire-averaged EF of dichloromethane or CH2Cl2, (6.9 ± 8.6) ×10-4 g kg-1, was not significantly different from zero and supports recent findings that its global biomass burning source appears to have been overestimated. Similarly, we found no evidence for emissions of chloroform (CHCl3) or methyl chloroform (CH3CCl3) from

  7. Boreal forest fire emissions in fresh Canadian smoke plumes: C1-C10 volatile organic compounds (VOCs), CO2, CO, NO2, NO, HCN and CH3CN

    NASA Astrophysics Data System (ADS)

    Simpson, I. J.; Akagi, S. K.; Barletta, B.; Blake, N. J.; Choi, Y.; Diskin, G. S.; Fried, A.; Fuelberg, H. E.; Meinardi, S.; Rowland, F. S.; Vay, S. A.; Weinheimer, A. J.; Wennberg, P. O.; Wiebring, P.; Wisthaler, A.; Yang, M.; Yokelson, R. J.; Blake, D. R.

    2011-07-01

    Boreal regions comprise about 17 % of the global land area, and they both affect and are influenced by climate change. To better understand boreal forest fire emissions and plume evolution, 947 whole air samples were collected aboard the NASA DC-8 research aircraft in summer 2008 as part of the ARCTAS-B field mission, and analyzed for 79 non-methane volatile organic compounds (NMVOCs) using gas chromatography. Together with simultaneous measurements of CO2, CO, CH4, CH2O, NO2, NO, HCN and CH3CN, these measurements represent the most comprehensive assessment of trace gas emissions from boreal forest fires to date. Based on 105 air samples collected in fresh Canadian smoke plumes, 57 of the 80 measured NMVOCs (including CH2O) were emitted from the fires, including 45 species that were quantified from boreal forest fires for the first time. After CO2, CO and CH4, the largest emission factors (EFs) for individual species were formaldehyde (2.1 ± 0.2 g kg-1), followed by methanol, NO2, HCN, ethene, α-pinene, β-pinene, ethane, benzene, propene, acetone and CH3CN. Globally, we estimate that boreal forest fires release 2.4 ± 0.6 Tg C yr-1 in the form of NMVOCs, with approximately 41 % of the carbon released as C1-C2 NMVOCs and 21 % as pinenes. These are the first reported field measurements of monoterpene emissions from boreal forest fires, and we speculate that the pinenes, which are relatively heavy molecules, were detected in the fire plumes as the result of distillation of stored terpenes as the vegetation is heated. Their inclusion in smoke chemistry models is expected to improve model predictions of secondary organic aerosol (SOA) formation. The fire-averaged EF of dichloromethane or CH2Cl2, (6.9 ± 8.6) × 10-4 g kg-1, was not significantly different from zero and supports recent findings that its global biomass burning source appears to have been overestimated. Similarly, we found no evidence for emissions of chloroform (CHCl3) or methyl chloroform (CH3CCl3

  8. Structural Insights into the Functional Role of the Hcn Sub-domain of the Receptor-Binding Domain of the Botulinum Neurotoxin Mosaic Serotype C/D

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, Yanfeng; Gardberg, Anna; Edwards, Tom E.

    Botulinum neurotoxin (BoNT), the causative agent of the deadly neuroparalytic disease botulism, is the most poisonous protein known for humans. Produced by different strains of the anaerobic bacterium Clostridium botulinum, BoNT effects cellular intoxication via a multistep mechanism executed by the three modules of the activated protein. Endocytosis, the first step of cellular intoxication, is triggered by the ~50 kDa, heavy-chain receptor-binding module (HCR) that is specific for a ganglioside and a protein receptor on neuronal cell surfaces. This dual receptor recognition mechanism between BoNT and the host cell’s membrane is well documented and occurs via specific intermolecular interactions withmore » the C-terminal sub-domain, Hcc, of BoNT-HCR. The N-terminal sub-domain of BoNT-HCR, Hcn, comprises ~50% of BoNT-HCR and adopts a B-sheet jelly roll fold. While suspected in assisting cell surface recognition, no unambiguous function for the Hcn sub-domain in BoNT has been indentified. To obtain insights into the potential function of the Hcn sub-domain in BoNT, the first crystal structure of a BoNT with an organic ligand bound to the Hcn sub-domain has been obtained. Here, we describe the crystal structure of BoNT/CD-HCR determined at 1.70 Å resolution with a tetraethylene glycol (PG4) molecule bound in an hydrophobic cleft between B-strands in the B-sheet jelly fold roll of the Hcn sub-domain. The molecule is completely engulfed in the cleft, making numerous hydrophobic (Y932, S959, W966, and D1042) and hydrophilic (S935, W977, L979, N1013, and I1066) contacts with the protein’s side chain and backbone that may mimic in vivo interactions with the phospholipid membranes on neuronal cell surfaces. A sulfate ion was also observed bound to residues T1176, D1177, K1196, and R1243 in the Hcc sub-domain of BoNT/CD-HCR. In the crystal structure of a similar protein, BoNT/D-HCR, a sialic acid« less

  9. Structural insights into the functional role of the Hcn sub-domain of the receptor-binding domain of the botulinum neurotoxin mosaic serotype C/D.

    PubMed

    Zhang, Yanfeng; Gardberg, Anna S; Edwards, Thomas E; Sankaran, Banumathi; Robinson, Howard; Varnum, Susan M; Buchko, Garry W

    2013-07-01

    Botulinum neurotoxin (BoNT), the causative agent of the deadly neuroparalytic disease botulism, is the most poisonous protein known for humans. Produced by different strains of the anaerobic bacterium Clostridium botulinum, BoNT effects cellular intoxication via a multistep mechanism executed by the three modules of the activated protein. Endocytosis, the first step of cellular intoxication, is triggered by the ~50 kDa, heavy-chain receptor-binding domain (HCR) that is specific for a ganglioside and a protein receptor on neuronal cell surfaces. This dual receptor recognition mechanism between BoNT and the host cell's membrane is well documented and occurs via specific intermolecular interactions with the C-terminal sub-domain, Hcc, of BoNT-HCR. The N-terminal sub-domain of BoNT-HCR, Hcn, comprises ~50% of BoNT-HCR and adopts a β-sheet jelly roll fold. While suspected in assisting cell surface recognition, no unambiguous function for the Hcn sub-domain in BoNT has been identified. To obtain insights into the potential function of the Hcn sub-domain in BoNT, the first crystal structure of a BoNT with an organic ligand bound to the Hcn sub-domain has been obtained. Here, we describe the crystal structure of BoNT/CD-HCR determined at 1.70 Å resolution with a tetraethylene glycol (PG4) moiety bound in a hydrophobic cleft between β-strands in the β-sheet jelly roll fold of the Hcn sub-domain. The PG4 moiety is completely engulfed in the cleft, making numerous hydrophilic (Y932, S959, W966, and D1042) and hydrophobic (S935, W977, L979, N1013, and I1066) contacts with the protein's side chain and backbone that may mimic in vivo interactions with the phospholipid membranes on neuronal cell surfaces. A sulfate ion was also observed bound to residues T1176, D1177, K1196, and R1243 in the Hcc sub-domain of BoNT/CD-HCR. In the crystal structure of a similar protein, BoNT/D-HCR, a sialic acid molecule was observed bound to the equivalent residues suggesting that residues T

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

    PubMed

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  12. Nitrogen and hydrogen fractionation in high-mass star-forming cores from observations of HCN and HNC

    NASA Astrophysics Data System (ADS)

    Colzi, L.; Fontani, F.; Caselli, P.; Ceccarelli, C.; Hily-Blant, P.; Bizzocchi, L.

    2018-02-01

    The ratio between the two stable isotopes of nitrogen, 14N and 15N, is well measured in the terrestrial atmosphere ( 272), and for the pre-solar nebula ( 441, deduced from the solar wind). Interestingly, some pristine solar system materials show enrichments in 15N with respect to the pre-solar nebula value. However, it is not yet clear if and how these enrichments are linked to the past chemical history because we have only a limited number of measurements in dense star-forming regions. In this respect, dense cores, which are believed to be the precursors of clusters and also contain intermediate- and high-mass stars, are important targets because the solar system was probably born within a rich stellar cluster, and such clusters are formed in high-mass star-forming regions. The number of observations in such high-mass dense cores has remained limited so far. In this work, we show the results of IRAM-30 m observations of the J = 1-0 rotational transition of the molecules HCN and HNC and their 15N-bearing counterparts towards 27 intermediate- and high-mass dense cores that are divided almost equally into three evolutionary categories: high-mass starless cores, high-mass protostellar objects, and ultra-compact HII regions. We have also observed the DNC(2-1) rotational transition in order to search for a relation between the isotopic ratios D/H and 14N/15N. We derive average 14N/15N ratios of 359 ± 16 in HCN and of 438 ± 21 in HNC, with a dispersion of about 150-200. We find no trend of the 14N/15N ratio with evolutionary stage. This result agrees with what has been found for N2H+ and its isotopologues in the same sources, although the 14N/15N ratios from N2H+ show a higher dispersion than in HCN/HNC, and on average, their uncertainties are larger as well. Moreover, we have found no correlation between D/H and 14N/15N in HNC. These findings indicate that (1) the chemical evolution does not seem to play a role in the fractionation of nitrogen, and that (2) the

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

    NASA Astrophysics Data System (ADS)

    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.

  14. The role of KCNQ1/KCNE1 K(+) channels in intestine and pancreas: lessons from the KCNE1 knockout mouse.

    PubMed

    Warth, R; Garcia Alzamora, M; Kim, J K; Zdebik, A; Nitschke, R; Bleich, M; Gerlach, U; Barhanin, J; Kim, S J

    2002-03-01

    KCNE1 (IsK, minK) co-assembles with KCNQ1 (KvLQT1) to form voltage-dependent K(+) channels. Both KCNQ1 and KCNE1 are expressed in epithelial cells of gut and exocrine pancreas. We examined the role of KCNQ1/KCNE1 in Cl(-) secretion in small and large intestine and exocrine pancreas using the KCNE1 knockout mouse. Immunofluorescence revealed a similar basolateral localization of KCNQ1 in jejunum and colon of KCNE1 wild-type and knockout mice. Electrogenic Cl(-) secretion in the colon was not affected by gene disruption of KCNE1; in jejunum forskolin-induced short-circuit current was some 40% smaller but without being significantly different. Inhibition of KCNQ1 channels by 293B (IC(50) 1 micromol l(-1)) and by IKS224 (IC(50) 14 nmol l(-1)) strongly diminished intestinal Cl(-) secretion. In exocrine pancreas of wild-type mice, KCNQ1 was predominantly located at the basolateral membrane. In KCNE1 knockout mice, however, the basolateral staining was less pronounced and the distribution of secretory granules was irregular. A slowly activating and 293B-sensitive K(+) current was activated via cholinergic stimulation in pancreatic acinar cells of wild-type mice. In KCNE1 knockout mice this K(+) current was strongly reduced. In conclusion intestinal Cl(-) secretion is independent from KCNE1 but requires KCNQ1. In mouse pancreatic acini KCNQ1 probably co-assembled with KCNE1 leads to a voltage-dependent K(+) current that might be of importance for electrolyte and enzyme secretion.

  15. HCN J = 4–3, HNC J = 1–0, H13CN J = 1–0, and HC3N J = 10–9 Maps of the Galactic Center Region. I. Spatially Resolved Measurements of Physical Conditions and Chemical Composition

    NASA Astrophysics Data System (ADS)

    Tanaka, Kunihiko; Nagai, Makoto; Kamegai, Kazuhisa; Iino, Takahiro; Sakai, Takeshi

    2018-06-01

    This supplement paper presents the maps of HCN J = 4–3, HNC J = 1–0, {{{H}}}13{CN} J = 1–0, and HC3N J = 10–9 for the Galactic central molecular zone (CMZ), which have been obtained using the Atacama Submillimeter Telescope Experiment and Nobeyama Radio Observatory 45 m telescope. Three-dimensional maps (2D in space and 1D in velocity) of the gas kinetic temperature (T kin), hydrogen volume density ({n}{{{H}}2}), and fractional abundances of eight molecules (HCN, HNC, {HC}}3{{N}}, HCO+, {{{H}}}2{CO}, SiO, CS, and {{{N}}}2{{{H}}}+) have been constructed from our and archival data. We have developed a method with hierarchical Bayesian inference for this analysis, which has successfully suppressed the artificial correlations among the parameters created by systematic errors due to the deficiency in the simple one-zone excitation analysis and the calibration uncertainty. The typical values of T kin and {n}{{{H}}2} are {10}1.8 {{K}} and {10}4.2 {cm}}-3, respectively, and the presence of an additional cold, low-density component is also indicated. The distribution of high-temperature regions is poorly correlated with known active star-forming regions, while a few of them coincide with shocked clouds. Principal component analysis has identified two distinct groups in the eight analyzed molecules: one group with large PC1 and PC2 scores, and the other with a large T kin dependence, which could be explained using two regimes of shock chemistry with fast (≳ 20 {km} {{{s}}}-1) and slow (≲ 20 {km} {{{s}}}-1) velocity shocks, respectively. This supports the idea that the mechanical sputtering of dust grains and the mechanical heating play primary roles in the chemical and thermal processes in CMZ clouds.

  16. Computational Studies Of Chemical Reactions: The Hnc-Hcn And Ch[subscript3]Nc-Ch[subscript3]Cn Isomerizations

    ERIC Educational Resources Information Center

    Halpern, Arthur M.

    2006-01-01

    The application of computational methods to the isomerization of hydrogen isocyanide to hydrogen cyanide, HNC-HCN is described. The logical extension to the exercise is presented to the isomerization of the methyl-substituted compounds, methylisocyanide and methylcyanide, Ch[subscript 3]NC-CH[subscript3]CN.

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

    PubMed

    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.

  18. Measurement of electron density profiles on HT-6M tokamak by 7-channel FIR HCN laser interferometer

    NASA Astrophysics Data System (ADS)

    Xiang, Gao; Qiliang, Guo

    1990-12-01

    Electron density measurements are periormed on HT-6M tokamak using a 7 channel Far-Infrared HCN laser interferometer. From the measured line integrals--7 channel phase shifts the electron density profile is reconstructed by a fit procedure. Results were tested by comparison to Abel inverted. Some recent interesting experimental results were reported.

  19. Synergistic modulation of KCNQ1/KCNE1 K(+) channels (IKs) by phosphatidylinositol 4,5-bisphosphate (PIP2) and [ATP]i.

    PubMed

    Kienitz, Marie-Cécile; Vladimirova, Dilyana

    2015-07-01

    Cardiac KCNQ1/KCNE1 channels (IKs) are dependent on the concentration of membrane phosphatidylinositol-4,5-bisphosphate (PIP2) and on cytosolic ATP by two distinct mechanisms. In this study we measured IKs and FRET between PH-PLCδ-based fluorescent PIP2 sensors in a stable KCNQ1/KCNE1 CHO cell line. Effects of activating either a muscarinic M3 receptor or the switchable phosphatase Ci-VSP on IKs were analyzed. Recovery of IKs from inhibition induced by muscarinic stimulation was incomplete despite full PIP2 resynthesis. Recovery of IKs was completely suppressed under ATP-free conditions, but partially restored by the ATP analog AMP-PCP, providing evidence that depletion of intracellular ATP inhibits IKs independent of PIP2-depletion. Simultaneous patch-clamp and FRET measurements in cells co-expressing Ci-VSP and the PIP2-FRET sensor revealed a component of IKs inhibition directly related to dynamic PIP2-depletion. A second component of inhibition was independent of acute changes in PIP2 and could be mimicked by ATP-free pipette solution, suggesting that it results from intracellular ATP-depletion. The reduction of intracellular ATP upon Ci-VSP activation appears to be independent of its activity as a phosphoinositide phosphatase. Our data demonstrate that ATP-depletion slowed IKs activation but had no short-term effect on PIP2 regeneration, suggesting that impaired PIP2-resynthesis cannot account for the rapid IKs inhibition by ATP-depletion. Furthermore, the second component of IKs inhibition by Ci-VSP was reduced by AMP-PCP in the pipette filling solution, indicating that direct binding of ATP to the KCNQ1/KCNE1 complex is required for voltage activation of IKs. We suggest that fluctuations of the cellular metabolic state regulate IKs in parallel with Gq-coupled PLC activation and PIP2-depletion. Copyright © 2015 Elsevier Inc. All rights reserved.

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

    PubMed

    Shamgar, Liora; Haitin, Yoni; Yisharel, Ilanit; Malka, Eti; Schottelndreier, Hella; Peretz, Asher; Paas, Yoav; Attali, Bernard

    2008-04-09

    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.

  1. KCNE1 Constrains the Voltage Sensor of Kv7.1 K+ Channels

    PubMed Central

    Yisharel, Ilanit; Malka, Eti; Schottelndreier, Hella; Peretz, Asher; Paas, Yoav; Attali, Bernard

    2008-01-01

    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. PMID:18398469

  2. How does KCNE1 regulate the Kv7.1 potassium channel? Model-structure, mutations, and dynamics of the Kv7.1-KCNE1 complex.

    PubMed

    Gofman, Yana; Shats, Simona; Attali, Bernard; Haliloglu, Turkan; Ben-Tal, Nir

    2012-08-08

    The voltage-gated potassium channel Kv7.1 and its auxiliary subunit KCNE1 are expressed in the heart and give rise to the major repolarization current. The interaction of Kv7.1 with the single transmembrane helix of KCNE1 considerably slows channel activation and deactivation, raises single-channel conductance, and prevents slow voltage-dependent inactivation. We built a Kv7.1-KCNE1 model-structure. The model-structure agrees with previous disulfide mapping studies and enables us to derive molecular interpretations of electrophysiological recordings that we obtained for two KCNE1 mutations. An elastic network analysis of Kv7.1 fluctuations in the presence and absence of KCNE1 suggests a mechanistic perspective on the known effects of KCNE1 on Kv7.1 function: slow deactivation is attributed to the low mobility of the voltage-sensor domains upon KCNE1 binding, abolishment of voltage-dependent inactivation could result from decreased fluctuations in the external vestibule, and amalgamation of the fluctuations in the pore region is associated with enhanced ion conductivity. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. SPATIALLY RESOLVED HCN J = 4-3 AND CS J = 7-6 EMISSION FROM THE DISK AROUND HD 142527

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Van der Plas, G.; Casassus, S.; Perez, S.

    2014-09-10

    The disk around HD 142527 attracts a great amount of attention compared to others because of its resolved (sub-)millimeter dust continuum that is concentrated into the shape of a horseshoe toward the north of the star. In this Letter we present spatially resolved ALMA detections of the HCN J = 4-3 and CS J = 7-6 emission lines. These lines give us a deeper view into the disk compared to the (optically thicker) CO isotopes. This is the first detection of CS J = 7-6 coming from a protoplanetary disk. Both emission lines are azimuthally asymmetric and are suppressed under the horseshoe-shapedmore » continuum emission peak. A possible mechanism for explaining the decrease under the horseshoe-shaped continuum is the increased opacity coming from the higher dust concentration at the continuum peak. Lower dust and/or gas temperatures and an optically thick radio-continuum reduce line emission by freezing out and shielding emission from the far side of the disk.« less

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

    PubMed

    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.

  5. Insulin treatment augments KCNQ1/KCNE1 currents but not KCNQ1 currents, which is associated with an increase in KCNE1 expression.

    PubMed

    Wu, Minghua; Obara, Yutaro; Ohshima, Shingo; Nagasawa, Yoshinobu; Ishii, Kuniaki

    2017-11-04

    Diabetes mellitus affects ion channel physiology. We have previously reported that acute application of insulin suppresses the KCNQ1/KCNE1 currents that play an important role in terminating ventricular action potential. In this study, we investigated the effect of long-term insulin treatment on KCNQ1/KCNE1 currents using the Xenopus oocyte expression system. Insulin treatment with a duration longer than 6 h had an opposite effect to acute insulin application, that is, it augmented the KCNQ1/KCNE1 currents. Inhibitors of PI3K, wortmannin and LY294002, and a MEK inhibitor, U0126, abolished the potentiating effect of long-term insulin treatment. The long-term treatment with insulin had no effect on KCNQ1 currents indicating an essential role of KCNE1 in the insulin effect, which is similar to the acute insulin effect. Cycloheximide, an inhibitor of protein synthesis, and brefeldin A, an inhibitor of protein transport from endoplasmic reticulum, suppressed the long-term insulin effect. Western blotting analysis combined with these pharmacological data suggest that long-term insulin treatment augments KCNQ1/KCNE1 currents by increasing KCNE1 protein expression. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Electron-impact excitation of the low-lying electronic states of HCN

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Tanaka, H.; Srivastava, S. K.; Wicke, B. G.

    1977-01-01

    The first study of the low-energy electron-impact excitation of low-lying electronic transitions in the HCN molecule is reported. Measurements were made at incident electron energies of 11.6 and 21.6 eV in the energy-loss range of 3-10 eV, and at scattering angles of 20-130 deg. Inelastic scattering spectra were placed on the absolute cross-section scale by determining first the ratio of inelastic-to-elastic scattering cross sections, and then separately measuring the absolute elastic scattering cross section. Several new electronic transitions are observed which are intrinsically overlapped in the molecule itself. Assignments of these electronic transitions are suggested. These assignments are based on present spectroscopic and cross-sections measurements, high-energy electron scattering spectra, optical absorption spectra, and ab initio molecular orbital calculations.

  7. Kcne2 deletion attenuates acute post-ischaemia/reperfusion myocardial infarction

    PubMed Central

    Hu, Zhaoyang; Crump, Shawn M.; Zhang, Ping; Abbott, Geoffrey W.

    2016-01-01

    Aims Most cardiac arrhythmia-associated genes encode ion channel subunits and regulatory proteins that are also expressed outside the heart, suggesting that diseases linked to their disruption may be multifactorial. KCNE2 is a ubiquitously expressed potassium channel β subunit associated with cardiac arrhythmia, atherosclerosis, and myocardial infarction (MI) in human populations. Here, we tested the hypothesis that Kcne2 disruption in mice would influence the acute outcome of experimentally induced MI. Methods and results One-year-old male Kcne2+/+ and Kcne2−/− mice were subjected to cardiac ischaemia/reperfusion injury (IRI) by left anterior descending coronary artery ligation. After reperfusion (3 h), infarct size and markers of tissue damage were quantified. Unexpectedly, post-reperfusion, Kcne2−/− mice exhibited 40% lower infarct size, decreased myocardial apoptosis and damage, and more than two-fold lower serum levels of damage markers, lactate dehydrogenase and creatine kinase, than Kcne2+/+ mice. Kcne2 deletion, despite increasing normalized heart weight and prolonging baseline QTc by 70%, helped preserve post-infarct cardiac function (quantified by a Millar catheter), with parameters including left ventricular maximum pressure, max dP/dt (P < 0.01), contractility index, and pressure/time index (P < 0.05) all greater in Kcne2−/− compared with Kcne2+/+ mice. Western blotting indicated two-fold-increased glycogen synthase kinase 3β (GSK-3β) phosphorylation (inactivation) before and after IRI (P < 0.05) in Kcne2−/− mice compared with Kcne2+/+ mice. GSK-3β inhibition by SB216763 mimicked in Kcne2+/+ mice the cardioprotective effects of Kcne2 deletion, but did not further enhance them in Kcne2−/− mice, suggesting that GSK-3β inactivation was a primary cardioprotective mechanism arising from Kcne2 deletion. Conclusions Kcne2 deletion preconditions the heart, attenuating the acute tissue damage caused by an imposed IRI. The findings

  8. 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

    NASA Astrophysics Data System (ADS)

    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.

  9. KCNQ and KCNE Potassium Channel Subunit Expression in Bovine Retinal Pigment Epithelium

    PubMed Central

    Zhang, Xiaoming; Hughes, Bret A.

    2013-01-01

    Human, monkey, and bovine retinal pigment epithelial (RPE) cells exhibit an M-type K+ current, which in many other cell types is mediated by channels composed of KCNQ α-subunits and KCNE auxiliary subunits. Recently, we demonstrated the expression of KCNQ1, KCNQ4, and KCNQ5 in the monkey RPE. Here, we investigated the expression of KCNQ and KCNE subunits in native bovine RPE. RT-PCR analysis revealed the expression of KCNQ1, KCNQ4, and KCNQ5 transcripts in the RPE, but, in Western blot analysis of RPE plasma membranes, only KCNQ5 was detected. Among the five members of the KCNE gene family, transcripts for KCNE1, KCNE2, KCNE3, and KCNE4 were detected in bovine RPE, but only KCNE1 and KCNE2 proteins were detected. Immunohistochemistry of frozen bovine retinal sections revealed KCNE1 expression near the apical and basal membranes of the RPE, in cone outer segments, in the outer nuclear layer, and throughout the inner retina. The localization of KCNE1 in the RPE basal membrane, where KCNQ5 was previously found to be present, suggests that this β-subunit may contribute to M-type K+ channels in this membrane. PMID:24416770

  10. KCNQ1, KCNE2, and Na+-Coupled Solute Transporters Form Reciprocally Regulating Complexes that Affect Neuronal Excitability

    PubMed Central

    Abbott, Geoffrey W.; Tai, Kwok-Keung; Neverisky, Daniel; Hansler, Alex; Hu, Zhaoyang; Roepke, Torsten K.; Lerner, Daniel J.; Chen, Qiuying; Liu, Li; Zupan, Bojana; Toth, Miklos; Haynes, Robin; Huang, Xiaoping; Demirbas, Didem; Buccafusca, Roberto; Gross, Steven S.; Kanda, Vikram A.; Berry, Gerard T.

    2014-01-01

    Na+-coupled solute transport is crucial for the uptake of nutrients and metabolic precursors, such as myo-inositol, an important osmolyte and precursor for various cell signaling molecules. Here, we found that various solute transporters and potassium channel subunits formed complexes and reciprocally regulated each other in vitro and in vivo. Global metabolite profiling revealed that mice lacking KCNE2, a K+ channel β subunit, showed a reduction in the myo-inositol concentration in cerebrospinal fluid (CSF) but not in serum. Increased behavorial responsiveness to stress and seizure susceptibility in Kcne2−/− mice were alleviated by injections of myo-inositol. Suspecting a defect in myo-inositol transport, we found that KCNE2 and KCNQ1, a voltage-gated potassium channel α subunit, colocalized and coimmunoprecipitated with SMIT1, a Na+-coupled myo-inositol transporter, in the choroid plexus epithelium. Heterologous coexpression demonstrated that myo-inositol transport by SMIT1 was augmented by coexpression of KCNQ1 but inhibited by coexpression of both KCNQ1 and KCNE2, which form a constitutively active, heteromeric K+ channel. SMIT1 and the related transporter SMIT2 were also inhibited by a constitutively active mutant form of KCNQ1. The activity of KCNQ1 and KCNQ1-KCNE2 were augmented by SMIT1 and the glucose transporter SGLT1, but suppressed by SMIT2. Channel-transporter signaling complexes may be a widespread mechanism to facilitate solute transport and electrochemical crosstalk. PMID:24595108

  11. KCNQ1, KCNE2, and Na+-coupled solute transporters form reciprocally regulating complexes that affect neuronal excitability.

    PubMed

    Abbott, Geoffrey W; Tai, Kwok-Keung; Neverisky, Daniel L; Hansler, Alex; Hu, Zhaoyang; Roepke, Torsten K; Lerner, Daniel J; Chen, Qiuying; Liu, Li; Zupan, Bojana; Toth, Miklos; Haynes, Robin; Huang, Xiaoping; Demirbas, Didem; Buccafusca, Roberto; Gross, Steven S; Kanda, Vikram A; Berry, Gerard T

    2014-03-04

    Na(+)-coupled solute transport is crucial for the uptake of nutrients and metabolic precursors, such as myo-inositol, an important osmolyte and precursor for various cell signaling molecules. We found that various solute transporters and potassium channel subunits formed complexes and reciprocally regulated each other in vitro and in vivo. Global metabolite profiling revealed that mice lacking KCNE2, a K(+) channel β subunit, showed a reduction in myo-inositol concentration in cerebrospinal fluid (CSF) but not in serum. Increased behavioral responsiveness to stress and seizure susceptibility in Kcne2(-/-) mice were alleviated by injections of myo-inositol. Suspecting a defect in myo-inositol transport, we found that KCNE2 and KCNQ1, a voltage-gated potassium channel α subunit, colocalized and coimmunoprecipitated with SMIT1, a Na(+)-coupled myo-inositol transporter, in the choroid plexus epithelium. Heterologous coexpression demonstrated that myo-inositol transport by SMIT1 was augmented by coexpression of KCNQ1 but was inhibited by coexpression of both KCNQ1 and KCNE2, which form a constitutively active, heteromeric K(+) channel. SMIT1 and the related transporter SMIT2 were also inhibited by a constitutively active mutant form of KCNQ1. The activities of KCNQ1 and KCNQ1-KCNE2 were augmented by SMIT1 and the glucose transporter SGLT1 but were suppressed by SMIT2. Channel-transporter signaling complexes may be a widespread mechanism to facilitate solute transport and electrochemical crosstalk.

  12. Ivabradine prolongs phase 3 of cardiac repolarization and blocks the hERG1 (KCNH2) current over a concentration-range overlapping with that required to block HCN4.

    PubMed

    Lees-Miller, James P; Guo, Jiqing; Wang, Yibo; Perissinotti, Laura L; Noskov, Sergei Y; Duff, Henry J

    2015-08-01

    In Europe, ivabradine has recently been approved to treat patients with angina who have intolerance to beta blockers and/or heart failure. Ivabradine is considered to act specifically on the sinoatrial node by inhibiting the If current (the funny current) to slow automaticity. However, in vitro studies show that ivabradine prolongs phase 3 repolarization in ventricular tissue. No episodes of Torsades de Pointes have been reported in randomized clinical studies. The objective of this study is to assess whether ivabradine blocked the hERG1 current. In the present study we discovered that ivabradine prolongs action potential and blocks the hERG current over a range of concentrations overlapping with those required to block HCN4. Ivabradine produced tonic, rather than use-dependent block. The mutation Y652A significantly suppressed pharmacologic block of hERG by ivabradine. Disruption of C-type inactivation also suppressed block of hERG1 by ivabradine. Molecular docking and molecular dynamics simulations indicate that ivabradine may access the inner cavity of the hERG1 via a lipophilic route and has a well-defined binding site in the closed state of the channel. Structural organization of the binding pockets for ivabradine is discussed. Ivabradine blocks hERG and prolongs action potential duration. Our study is potentially important because it indicates the need for active post marketing surveillance of ivabradine. Importantly, proarrhythmia of a number of other drugs has only been discovered during post marketing surveillance. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. K2P TASK-2 and KCNQ1-KCNE3 K+ channels are major players contributing to intestinal anion and fluid secretion.

    PubMed

    Julio-Kalajzić, Francisca; Villanueva, Sandra; Burgos, Johanna; Ojeda, Margarita; Cid, L Pablo; Jentsch, Thomas J; Sepúlveda, Francisco V

    2018-02-01

    K + channels are important in intestinal epithelium as they ensure the ionic homeostasis and electrical potential of epithelial cells during anion and fluid secretion. Intestinal epithelium cAMP-activated anion secretion depends on the activity of the (also cAMP dependent) KCNQ1-KCNE3 K + channel, but the secretory process survives after genetic inactivation of the K + channel in the mouse. Here we use double mutant mice to investigate which alternative K + channels come into action to compensate for the absence of KCNQ1-KCNE3 K + channels. Our data establish that whilst Ca 2+ -activated K Ca 3.1 channels are not involved, K 2P two-pore domain TASK-2 K + channels are major players providing an alternative conductance to sustain the intestinal secretory process. Work with double mutant mice lacking both TASK-2 and KCNQ1-KCNE3 channels nevertheless points to yet-unidentified K + channels that contribute to the robustness of the cAMP-activated anion secretion process. Anion and fluid secretion across the intestinal epithelium, a process altered in cystic fibrosis and secretory diarrhoea, is mediated by cAMP-activated CFTR Cl - channels and requires the simultaneous activity of basolateral K + channels to maintain cellular ionic homeostasis and membrane potential. This function is fulfilled by the cAMP-activated K + channel formed by the association of pore-forming KCNQ1 with its obligatory KCNE3 β-subunit. Studies using mice show sizeable cAMP-activated intestinal anion secretion in the absence of either KCNQ1 or KCNE3 suggesting that an alternative K + conductance must compensate for the loss of KCNQ1-KCNE3 activity. We used double mutant mouse and pharmacological approaches to identify such a conductance. Ca 2+ -dependent anion secretion can also be supported by Ca 2+ -dependent K Ca 3.1 channels after independent CFTR activation, but cAMP-dependent anion secretion is not further decreased in the combined absence of K Ca 3.1 and KCNQ1-KCNE3 K + channel activity. We

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

    PubMed Central

    Royal, Alice A.

    2017-01-01

    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(4)P) 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(4)P 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(4)P for anterograde trafficking, but is heavily reliant on PIP2 for channel function once at the PM. PMID:29020060

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

    PubMed

    Royal, Alice A; Tinker, Andrew; Harmer, Stephen C

    2017-01-01

    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(4)P) 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(4)P 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(4)P for anterograde trafficking, but is heavily reliant on PIP2 for channel function once at the PM.

  16. The Natural Plant Product Rottlerin Activates Kv7.1/KCNE1 Channels.

    PubMed

    Matschke, Veronika; Piccini, Ilaria; Schubert, Janina; Wrobel, Eva; Lang, Florian; Matschke, Johann; Amedonu, Elsie; Meuth, Sven G; Strünker, Timo; Strutz-Seebohm, Nathalie; Greber, Boris; Scherkenbeck, Jürgen; Seebohm, Guiscard

    2016-01-01

    Acquired as well as inherited channelopathies are disorders that are caused by altered ion channel function. A family of channels whose malfunction is associated with different channelopathies is the Kv7 K+ channel family; and restoration of normal Kv7 channel function by small molecule modulators is a promising approach for treatment of these often fatal diseases. Here, we show the modulation of Kv7 channels by the natural compound Rottlerin heterologously expressed in Xenopus laevis oocytes and on iPSC cardiomyocytes overexpressing Kv7.1 channels. We show that currents carried by Kv7.1 (EC50 = 1.48 μM), Kv7.1/KCNE1 (EC50 = 4.9 μM), and Kv7.4 (EC50 = 0.148 μM) are strongly enhanced by the compound, whereas Kv7.2, Kv7.2/Kv7.3, and Kv7.5 are not sensitive to Rottlerin. Studies on Kv7.1/KCNE1 mutants and in silico modelling indicate that Rottlerin binds to the R-L3-activator site. Rottlerin mediated activation of Kv7.1/KCNE1 channels might be a promising approach in long QT syndrome. As a proof of concept, we show that Rottlerin shortens cardiac repolarisation in iPSC-derived cardiomyocytes expressing Kv7.1. Rottlerin or an optimized derivative holds a potential as QT interval correcting drug. © 2016 The Author(s) Published by S. Karger AG, Basel.

  17. Identification of a protein–protein interaction between KCNE1 and the activation gate machinery of KCNQ1

    PubMed Central

    Lvov, Anatoli; Gage, Steven D.; Berrios, Virla M.

    2010-01-01

    KCNQ1 channels assemble with KCNE1 transmembrane (TM) peptides to form voltage-gated K+ channel complexes with slow activation gate opening. The cytoplasmic C-terminal domain that abuts the KCNE1 TM segment has been implicated in regulating KCNQ1 gating, yet its interaction with KCNQ1 has not been described. Here, we identified a protein–protein interaction between the KCNE1 C-terminal domain and the KCNQ1 S6 activation gate and S4–S5 linker. Using cysteine cross-linking, we biochemically screened over 300 cysteine pairs in the KCNQ1KCNE1 complex and identified three residues in KCNQ1 (H363C, P369C, and I257C) that formed disulfide bonds with cysteine residues in the KCNE1 C-terminal domain. Statistical analysis of cross-link efficiency showed that H363C preferentially reacted with KCNE1 residues H73C, S74C, and D76C, whereas P369C showed preference for only D76C. Electrophysiological investigation of the mutant K+ channel complexes revealed that the KCNQ1 residue, H363C, formed cross-links not only with KCNE1 subunits, but also with neighboring KCNQ1 subunits in the complex. Cross-link formation involving the H363C residue was state dependent, primarily occurring when the KCNQ1KCNE1 complex was closed. Based on these biochemical and electrophysiological data, we generated a closed-state model of the KCNQ1KCNE1 cytoplasmic region where these protein–protein interactions are poised to slow activation gate opening. PMID:20479109

  18. A global ab initio potential for HCN/HNC, exact vibrational energies, and comparison to experiment

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    An ab initio (i.e., from first principles) calculation of vibrational energies of HCN and HNC is reported. The vibrational calculations were done with a new potential derived from a fit to 1124 ab initio electronic energies which were calculated using the highly accurate CCSD(T) coupled-cluster method in conjunction with a large atomic natural orbital basis set. The properties of this potential are presented, and the vibrational calculations are compared to experiment for 54 vibrational transitions, 39 of which are for zero total angular momentum, J = 0, and 15 of which are for J = 1. The level of agreement with experiment is unprecedented for a triatomic with two nonhydrogen atoms, and demonstrates the capability of the latest computational methods to give reliable predictions on a strongly bound triatomic molecule at very high levels of vibrational excitation.

  19. The photolysis of NH3 in the presence of substituted acetylenes - A possible source of oligomers and HCN on Jupiter

    NASA Technical Reports Server (NTRS)

    Ferris, James P.; Jacobson, Richard R.; Guillemin, Jean C.

    1992-01-01

    An NMR spectral study is presently conducted of NH3 photolysis in the presence of substituted acetylenes with NMR spectra and gas chromatography. Quantum yields and percentage conversions to products are reported. It is shown that acetylenic hydrocarbons generated during methane photolysis in Jupiter's stratosphere can react with radicals formed by NH3 photolysis to yield nonvolatile, yellow-brown polymers, alkylnitriles, and in due course, HCN, as observed on Jupiter.

  20. Cyanide Metabolism in Relation to Ethylene Production in Plant Tissues 1

    PubMed Central

    Yip, Wing-Kin; Yang, Shang Fa

    1988-01-01

    HCN is the putative product of C-1 and amino moieties of 1-aminocyclopropane-1-carboxylic acid (ACC) during its conversion to ethylene. In apple (Malus sylvestrus Mill.) slices or auxin-treated mungbean (Vigna radiata L.) hypocotyls, which produced ethylene at high rates, the steady state concentration of HCN was found to be no higher than 0.2 micromolar, which was too low to inhibit respiration (reported Ki for HCN to inhibit respiration was 10-20 micromolar). However, these tissues became cyanogenic when treated with ACC, the precursor of ethylene, and with 2-aminoxyacetic acid, which inhibits β-cyanoalanine synthase, the main enzyme to detoxify HCN; the HCN levels in these tissues went up to 1.7 and 8.1 micromolar, respectively. Although ethylene production by avocado (Persea gratissima) and apple fruits increased several hundred-fold during ripening, β-cyanoalanine synthase activity increased only one- to two-fold. These findings support the notion that HCN is a co-product of ethylene biosynthesis and that the plant tissues possess ample capacity to detoxify HCN formed during ethylene biosynthesis so that the concentration of HCN in plant tissues is kept at a low level. PMID:16666329

  1. A theoretical study of hydrogen complexes of the XH-pi type between propyne and HF, HCL or HCN.

    PubMed

    Tavares, Alessandra M; da Silva, Washington L V; Lopes, Kelson C; Ventura, Elizete; Araújo, Regiane C M U; do Monte, Silmar A; da Silva, João Bosco P; Ramos, Mozart N

    2006-05-15

    The present manuscript reports a systematic investigation of the basis set dependence of some properties of hydrogen-bonded (pi type) complexes formed by propyne and a HX molecule, where X=F, Cl and CN. The calculations have been performed at Hartree-Fock, MP2 and B3LYP levels. Geometries, H-bond energies and vibrational have been considered. The more pronounced effects on the structural parameters of the isolated molecules, as a result of complexation, are verified on RCtriple bondC and HX bond lengths. As compared to double-zeta (6-31G**), triple-zeta (6-311G**) basis set leads to an increase of RCtriple bondC bond distance, at all three computational levels. In the case where diffuse functions are added to both hydrogen and 'heavy' atoms, the effect is more pronounced. The propyne-HX structural parameters are quite similar to the corresponding parameters of acetylene-HX complexes, at all levels. The largest difference is obtained for hydrogen bond distance, RH, with a smaller value for propyne-HX complex, indicating a stronger bond. Concerning the electronic properties, the results yield the following ordering for H-bond energies, DeltaE: propynecdots, three dots, centeredHF>propynecdots, three dots, centeredHCl>propynecdots, three dots, centeredHCN. It is also important to point out that the inclusion of BSSE and zero-point energies (ZPE) corrections cause significant changes on DeltaE. The smaller effect of ZPE is obtained for propynecdots, three dots, centeredHCN at HF/6-311++G** level, while the greatest difference is obtained at MP2/6-31G** level for propynecdots, three dots, centeredHF system. Concerning the IR vibrational it was obtained that larger shift can be associated with stronger hydrogen bonds. The more pronounced effect on the normal modes of the isolated molecule after the complexation is obtained for HX stretching frequency, which is shifted downward.

  2. Prebiotic synthesis in atmospheres containing CH4, CO, and CO2. I - Amino acids

    NASA Technical Reports Server (NTRS)

    Schlesinger, G.; Miller, S. L.

    1983-01-01

    The prebiotic synthesis of amino acids, HCN, H2CO, and NH3 using a spark discharge on various simulated primitive earth atmospheres at 25 C is investigated. Various mixtures of CH4, CO, CO2, N2, NH3, H2O, and H2 were utilized in different experiments. The yields of amino acids (1.2-4.7 percent based on the carbon) are found to be approximately independent of the H2/CH4 ratio and the presence of NH3, and a wide variety of amino acids are obtained. Glycine is found to be almost the only amino acid produced from CO and CO2 model atmospheres, with the maximum yield being about the same for the three carbon sources at high H2/carbon ratios,whereas CH4 is superior at low H2/carbon ratios. In addition, it is found that the directly synthesized NH3 together with the NH3 obtained from the hydrolysis of HCN, nitriles, and urea could have been a major source of ammonia in the atmosphere and oceans of the primitive earth. It is determined that prebiotic syntheses from HCN and H2CO to give products such as purines and sugars and some amino acids could have occurred in primitive atmospheres containing CO and CO2 provided the H2/CO and H2/CO2 ratios were greater than about 1.0.

  3. The KCNE2 K+ channel regulatory subunit: ubiquitous influence, complex pathobiology

    PubMed Central

    Abbott, Geoffrey W.

    2015-01-01

    The KCNE single-span transmembrane subunits are encoded by five-member gene families in the human and mouse genomes. Primarily recognized for co-assembling with and functionally regulating the voltage-gated potassium channels, the broad influence of KCNE subunits in mammalian physiology belies their small size. KCNE2 has been widely studied since we first discovered one of its roles in the heart and its association with inherited and acquired human Long QT syndrome. Since then, physiological analyses together with human and mouse genetics studies have uncovered a startling array of functions for KCNE2, in the heart, stomach, thyroid and choroid plexus. The other side of this coin is the variety of interconnected disease manifestations caused by KCNE2 disruption, involving both excitable cells such as cardiomyocytes, and non-excitable, polarized epithelia. Kcne2 deletion in mice has been particularly instrumental in illustrating the potential ramifications within a monogenic arrhythmia syndrome, with removal of one piece revealing the unexpected complexity of the puzzle. Here, we review current knowledge of the function and pathobiology of KCNE2. PMID:26123744

  4. Impact of Hyperpolarization-activated, Cyclic Nucleotide-gated Cation Channel Type 2 for the Xenon-mediated Anesthetic Effect: Evidence from In Vitro and In Vivo Experiments.

    PubMed

    Mattusch, Corinna; Kratzer, Stephan; Buerge, Martina; Kreuzer, Matthias; Engel, Tatiana; Kopp, Claudia; Biel, Martin; Hammelmann, Verena; Ying, Shui-Wang; Goldstein, Peter A; Kochs, Eberhard; Haseneder, Rainer; Rammes, Gerhard

    2015-05-01

    The thalamus is thought to be crucially involved in the anesthetic state. Here, we investigated the effect of the inhaled anesthetic xenon on stimulus-evoked thalamocortical network activity and on excitability of thalamocortical neurons. Because hyperpolarization-activated, cyclic nucleotide-gated cation (HCN) channels are key regulators of neuronal excitability in the thalamus, the effect of xenon on HCN channels was examined. The effects of xenon on thalamocortical network activity were investigated in acutely prepared brain slices from adult wild-type and HCN2 knockout mice by means of voltage-sensitive dye imaging. The influence of xenon on single-cell excitability in brain slices was investigated using the whole-cell patch-clamp technique. Effects of xenon on HCN channels were verified in human embryonic kidney cells expressing HCN2 channels. Xenon concentration-dependently diminished thalamocortical signal propagation. In neurons, xenon reduced HCN channel-mediated Ih current amplitude by 33.4 ± 12.2% (at -133 mV; n = 7; P = 0.041) and caused a left-shift in the voltage of half-maximum activation (V1/2) from -98.8 ± 1.6 to -108.0 ± 4.2 mV (n = 8; P = 0.035). Similar effects were seen in human embryonic kidney cells. The impairment of HCN channel function was negligible when intracellular cyclic adenosine monophosphate level was increased. Using HCN2 mice, we could demonstrate that xenon did neither attenuate in vitro thalamocortical signal propagation nor did it show sedating effects in vivo. Here, we clearly showed that xenon impairs HCN2 channel function, and this impairment is dependent on intracellular cyclic adenosine monophosphate levels. We provide evidence that this effect reduces thalamocortical signal propagation and probably contributes to the hypnotic properties of xenon.

  5. A theoretical study of hydrogen complexes of the X sbnd H-π type between propyne and HF, HCL or HCN

    NASA Astrophysics Data System (ADS)

    Tavares, Alessandra M.; da Silva, Washington L. V.; Lopes, Kelson C.; Ventura, Elizete; Araújo, Regiane C. M. U.; do Monte, Silmar A.; da Silva, João Bosco P.; Ramos, Mozart N.

    2006-05-01

    The present manuscript reports a systematic investigation of the basis set dependence of some properties of hydrogen-bonded (π type) complexes formed by propyne and a HX molecule, where X = F, Cl and CN. The calculations have been performed at Hartree-Fock, MP2 and B3LYP levels. Geometries, H-bond energies and vibrational have been considered. The more pronounced effects on the structural parameters of the isolated molecules, as a result of complexation, are verified on RC tbnd C and HX bond lengths. As compared to double-ζ (6-31G **), triple-ζ (6-311G **) basis set leads to an increase of RC tbnd C bond distance, at all three computational levels. In the case where diffuse functions are added to both hydrogen and 'heavy' atoms, the effect is more pronounced. The propyne-HX structural parameters are quite similar to the corresponding parameters of acetylene-HX complexes, at all levels. The largest difference is obtained for hydrogen bond distance, RH, with a smaller value for propyne-HX complex, indicating a stronger bond. Concerning the electronic properties, the results yield the following ordering for H-bond energies, Δ E: propyne⋯HF > propyne⋯HCl > propyne⋯HCN. It is also important to point out that the inclusion of BSSE and zero-point energies (ZPE) corrections cause significant changes on Δ E. The smaller effect of ZPE is obtained for propyne⋯HCN at HF/6-311++G ** level, while the greatest difference is obtained at MP2/6-31G ** level for propyne⋯HF system. Concerning the IR vibrational it was obtained that larger shift can be associated with stronger hydrogen bonds. The more pronounced effect on the normal modes of the isolated molecule after the complexation is obtained for H sbnd X stretching frequency, which is shifted downward.

  6. Disruption of the potassium channel regulatory subunit KCNE2 causes iron-deficient anemia

    PubMed Central

    Salsbury, Grace; Cambridge, Emma L.; McIntyre, Zoe; Arends, Mark J.; Karp, Natasha A.; Isherwood, Christopher; Shannon, Carl; Hooks, Yvette; Ramirez-Solis, Ramiro; Adams, David J.; White, Jacqueline K.; Speak, Anneliese O.

    2014-01-01

    Iron homeostasis is a dynamic process that is tightly controlled to balance iron uptake, storage, and export. Reduction of dietary iron from the ferric to the ferrous form is required for uptake by solute carrier family 11 (proton-coupled divalent metal ion transporters), member 2 (Slc11a2) into the enterocytes. Both processes are proton dependent and have led to the suggestion of the importance of acidic gastric pH for the absorption of dietary iron. Potassium voltage-gated channel subfamily E, member 2 (KCNE2), in combination with potassium voltage-gated channel, KQT-like subfamily, member 1 (KCNQ1), form a gastric potassium channel essential for gastric acidification. Deficiency of either Kcne2 or Kcnq1 results in achlorhydia, gastric hyperplasia, and neoplasia, but the impact on iron absorption has not, to our knowledge, been investigated. Here we report that Kcne2-deficient mice, in addition to the previously reported phenotypes, also present with iron-deficient anemia. Interestingly, impaired function of KCNQ1 results in iron-deficient anemia in Jervell and Lange-Nielsen syndrome patients. We speculate that impaired function of KCNE2 could result in the same clinical phenotype. PMID:25127743

  7. 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

    NASA Astrophysics Data System (ADS)

    Hamid, Ahmed M.; El-Shall, M. Samy; Hilal, Rifaat; Elroby, Shaaban; Aziz, Saadullah G.

    2014-08-01

    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 C5H5N+.(HCN)n and C4H4N2+.(HCN)n clusters, respectively, with n = 1-4. For comparison, the binding of 1-4 HCN molecules to the protonated pyridine C5H5NH+(HCN)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 (CHδ+⋯NCH). Protonated pyridine forms a stronger ionic hydrogen bond with HCN (NH+⋯NCH) which can be extended to a linear chain with the clustering of additional HCN molecules (NH+⋯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 (CHδ+⋯NCH) formed between the pyridine or the pyrimidine radical cations and HCN molecules (11-12 kcal/mol) are stronger than the similar (CHδ+⋯NCH) bonds formed between the benzene radical cation and HCN molecules (9 kcal/mol) indicating that the CHδ+ centers in the pyridine and pyrimidine radical cations have more effective charges than in the benzene radical cation.

  8. 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.

    PubMed

    Hamid, Ahmed M; El-Shall, M Samy; Hilal, Rifaat; Elroby, Shaaban; Aziz, Saadullah G

    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 C5H5N(+·)(HCN)n and C4H4N2 (+·)(HCN)n clusters, respectively, with n = 1-4. For comparison, the binding of 1-4 HCN molecules to the protonated pyridine C5H5NH(+)(HCN)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(δ+)⋯NCH). Protonated pyridine forms a stronger ionic hydrogen bond with HCN (NH(+)⋯NCH) which can be extended to a linear chain with the clustering of additional HCN molecules (NH(+)⋯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(δ+)⋯NCH) formed between the pyridine or the pyrimidine radical cations and HCN molecules (11-12 kcal/mol) are stronger than the similar (CH(δ+)⋯NCH) bonds formed between the benzene radical cation and HCN molecules (9 kcal/mol) indicating that the CH(δ+) centers in the pyridine and pyrimidine radical cations have more effective charges than in the benzene radical cation.

  9. Molecular determinants of Kv7.1/KCNE1 channel inhibition by amitriptyline.

    PubMed

    Villatoro-Gómez, Kathya; Pacheco-Rojas, David O; Moreno-Galindo, Eloy G; Navarro-Polanco, Ricardo A; Tristani-Firouzi, Martin; Gazgalis, Dimitris; Cui, Meng; Sánchez-Chapula, José A; Ferrer, Tania

    2018-06-01

    Amitriptyline (AMIT) is a compound widely prescribed for psychiatric and non-psychiatric conditions including depression, migraine, chronic pain, and anorexia. However, AMIT has been associated with risks of cardiac arrhythmia and sudden death since it can induce prolongation of the QT interval on the surface electrocardiogram and torsade de pointes ventricular arrhythmia. These complications have been attributed to the inhibition of the rapid delayed rectifier potassium current (I Kr ). The slow delayed rectifier potassium current (I Ks ) is the main repolarizing cardiac current when I Kr is compromised and it has an important role in cardiac repolarization at fast heart rates induced by an elevated sympathetic tone. Therefore, we sought to characterize the effects of AMIT on Kv7.1/KCNE1 and homomeric Kv7.1 channels expressed in HEK-293H cells. Homomeric Kv7.1 and Kv7.1/KCNE1 channels were inhibited by AMIT in a concentration-dependent manner with IC50 values of 8.8 ± 2.1 μM and 2.5 ± 0.8 μM, respectively. This effect was voltage-independent for both homomeric Kv7.1 and Kv7.1/KCNE1 channels. Moreover, mutation of residues located on the P-loop and S6 domain along with molecular docking, suggest that T312, I337 and F340 are the most important molecular determinants for AMIT-Kv7.1 channel interaction. Our experimental findings and modeling suggest that AMIT preferentially blocks the open state of Kv7.1/KCNE1 channels by interacting with specific residues that were previously reported to be important for binding of other compounds, such as chromanol 293B and the benzodiazepine L7. Copyright © 2018 Elsevier Inc. All rights reserved.

  10. KCNE1 induces fenestration in the Kv7.1/KCNE1 channel complex that allows for highly specific pharmacological targeting

    NASA Astrophysics Data System (ADS)

    Wrobel, Eva; Rothenberg, Ina; Krisp, Christoph; Hundt, Franziska; Fraenzel, Benjamin; Eckey, Karina; Linders, Joannes T. M.; Gallacher, David J.; Towart, Rob; Pott, Lutz; Pusch, Michael; Yang, Tao; Roden, Dan M.; Kurata, Harley T.; Schulze-Bahr, Eric; Strutz-Seebohm, Nathalie; Wolters, Dirk; Seebohm, Guiscard

    2016-10-01

    Most small-molecule inhibitors of voltage-gated ion channels display poor subtype specificity because they bind to highly conserved residues located in the channel's central cavity. Using a combined approach of scanning mutagenesis, electrophysiology, chemical ligand modification, chemical cross-linking, MS/MS-analyses and molecular modelling, we provide evidence for the binding site for adamantane derivatives and their putative access pathway in Kv7.1/KCNE1 channels. The adamantane compounds, exemplified by JNJ303, are highly potent gating modifiers that bind to fenestrations that become available when KCNE1 accessory subunits are bound to Kv7.1 channels. This mode of regulation by auxiliary subunits may facilitate the future development of potent and highly subtype-specific Kv channel inhibitors.

  11. Pacemaker channels produce an instantaneous current.

    PubMed

    Proenza, Catherine; Angoli, Damiano; Agranovich, Eugene; Macri, Vincenzo; Accili, Eric A

    2002-02-15

    Spontaneous rhythmic activity in mammalian heart and brain depends on pacemaker currents (I(h)), which are produced by hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. Here, we report that the mouse HCN2 pacemaker channel isoform also produced a large instantaneous current (I(inst(HCN2))) in addition to the well characterized, slowly activating I(h). I(inst(HCN2)) was specific to expression of HCN2 on the plasma membrane and its amplitude was correlated with that of I(h). The two currents had similar reversal potentials, and both were modulated by changes in intracellular Cl(-) and cAMP. A mutation in the S4 domain of HCN2 (S306Q) decreased I(h) but did not alter I(inst(HCN2)), and instantaneous currents in cells expressing either wild type HCN2 or mutant S306Q channels were insensitive to block by Cs(+). Co-expression of HCN2 with the accessory subunit, MiRP1, decreased I(h) and increased I(inst(HCN2)), suggesting a mechanism for modulation of both currents in vivo. These data suggest that expression of HCN channels may be accompanied by a background conductance in native tissues and are consistent with at least two open states of HCN channels: I(inst(HCN2)) is produced by a Cs(+)-open state; hyperpolarization produces an additional Cs(+)-sensitive open state, which results in I(h).

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

    NASA Technical Reports Server (NTRS)

    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.

  13. 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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hamid, Ahmed M.; El-Shall, M. Samy, E-mail: mselshal@vcu.edu; Hilal, Rifaat

    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 = 14. For comparison, the binding of 14 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 themore » 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.« less

  14. Interaction between 2,4-Diacetylphloroglucinol- and Hydrogen Cyanide-Producing Pseudomonas brassicacearum LBUM300 and Clavibacter michiganensis subsp. michiganensis in the Tomato Rhizosphere

    PubMed Central

    Paulin, Mélanie M.; Novinscak, Amy; Lanteigne, Carine; Gadkar, Vijay J.

    2017-01-01

    ABSTRACT We have previously demonstrated that inoculation of tomato plants with 2,4-diacetylphloroglucinol (DAPG)- and hydrogen cyanide (HCN)-producing Pseudomonas brassicacearum LBUM300 could significantly reduce bacterial canker symptoms caused by Clavibacter michiganensis subsp. michiganensis. In this study, in order to better characterize the population dynamics of LBUM300 in the rhizosphere of tomato plants, we characterized the role played by DAPG and HCN production by LBUM300 on rhizosphere colonization of healthy and C. michiganensis subsp. michiganensis-infected tomato plants. The impact of C. michiganensis subsp. michiganensis presence on the expression of DAPG and HCN biosynthetic genes in the rhizosphere was also examined. In planta assays were performed using combinations of C. michiganensis subsp. michiganensis and wild-type LBUM300 or DAPG (LBUM300ΔphlD) or HCN (LBUM300ΔhcnC) isogenic mutant strains. Populations of LBUM300 and phlD and hcnC gene expression levels were quantified in rhizosphere soil at several time points up to 264 h postinoculation using culture-independent quantitative PCR (qPCR) and reverse transcriptase quantitative PCR (RT-qPCR) TaqMan assays, respectively. The presence of C. michiganensis subsp. michiganensis significantly increased rhizospheric populations of LBUM300. In C. michiganensis subsp. michiganensis-infected tomato rhizospheres, the populations of wild-type LBUM300 and strain LBUM300ΔhcnC, both producing DAPG, were significantly higher than the population of strain LBUM300ΔphlD. A significant upregulation of phlD expression was observed in the presence of C. michiganensis subsp. michiganensis, while hcnC expression was only slightly increased in the mutant strain LBUM300ΔphlD when C. michiganensis subsp. michiganensis was present. Additionally, biofilm production was found to be significantly reduced in strain LBUM300ΔphlD compared to the wild-type and LBUM300ΔhcnC strains. IMPORTANCE The results of this study

  15. Characteristics of hyperpolarization-activated cyclic nucleotide-gated channels in dorsal root ganglion neurons at different ages and sizes.

    PubMed

    Hou, Baohua; Chen, Hengling; Qu, Xiangwei; Lin, Xianguang; Luo, Fang; Li, Chenhong

    2015-11-11

    In rat's sensory neurons, hyperpolarization-activated inward currents (Ih) play an essential role in mediating action potentials and contributing to neuronal excitability. Classified by the size of neurons and ages, we studied the Ih and transcription levels of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels using electrophysiology and the single-cell RT-PCR. In voltage-clamp studies, Ih and half-maximal activation voltage (V1/2) changed with age and size. An analysis of all HCN subtypes in dorsal root ganglion (DRG) neurons by single-cell RT-PCR was carried out. HCN1 and HCN3 in medium-small elderly neurons had a weak expression. HCN2 in newborns and HCN4 in elderly rats also had a weak expression. The aim of this study is to examine the age-related Ih and HCN channels subunits in different ages and sizes of DRG neurons. The results would be significant in understanding the physiological and pathophysiological function of different sizes of DRG neurons in different age periods.

  16. β1-Adrenergic blocker bisoprolol reverses down-regulated ion channels in sinoatrial node of heart failure rats.

    PubMed

    Du, Yuan; Zhang, Junbo; Xi, Yutao; Wu, Geru; Han, Ke; Huang, Xin; Ma, Aiqun; Wang, Tingzhong

    2016-06-01

    Bisoprolol, an antagonist of β1-adrenergic receptors, is effective in reducing the morbidity and mortality in patients with heart failure (HF). It has been found that HF is accompanied with dysfunction of the sinoatrial node (SAN). However, whether bisoprolol reverses the decreased SAN function in HF and how the relevant ion channels in SAN change were relatively less studied. SAN function and messenger RNA (mRNA) expression of sodium channels and hyperpolarization-activated cyclic nucleotide-gated (HCN) channel subunits were assessed in sham-operated rats, abdominal arterio-venous shunt (volume overload)-induced HF rats, and bisoprolol- treated HF rats. SAN cells of rats were isolated by laser capture microdissection. Quantitative real-time PCR analysis was used to quantify mRNA expression of sodium channels and HCN channel subunits in SAN. Intrinsic heart rate declined and sinus node recovery time prolonged in HF rats, indicating the suppressed SAN function, which could be improved by bisoprolol treatment. Nav1.1, Nav1.6, and HCN4 mRNA expressions were reduced in SAN in HF rats compared with that in control rats. Treatment with bisoprolol could reverse both the SAN function and the Nav1.1, Nav1.6, and HCN4 mRNA expression partially. These data indicated that bisoprolol is effective in HF treatment partially due to improved SAN function by reversing the down-regulation of sodium channels (Nav1.1 and Nav1.6) and HCN channel (HCN4) subunits in SAN in failing hearts.

  17. 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.

    PubMed

    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).

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

    PubMed

    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.

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

    PubMed

    Pedersen, Philip J; Thomsen, Kirsten B; Flak, Jon B; Tejada, Maria A; Hauser, Frank; Trachsel, Dagmar; Buhl, Rikke; Kalbfleisch, Theodore; DePriest, Michael Scott; MacLeod, James N; Calloe, Kirstine; Klaerke, Dan A

    2017-08-01

    The voltage-gated K + -channel K V 7.1 and the subunit KCNE1, encoded by the KCNQ1 and KCNE1 genes, respectively, are responsible for termination of the cardiac action potential. In humans, mutations in these genes can predispose patients to arrhythmias and sudden cardiac death (SCD). To characterize equine K V 7.1/KCNE1 currents and compare them to human K V 7.1/KCNE1 currents to determine whether K V 7.1/KCNE1 plays a similar role in equine and human hearts. mRNA encoding K V 7.1 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. Equine K V 7.1/KCNE1 expressed in CHO-K1 cells exhibited electrophysiological properties that are overall similar to the human orthologs; however, a slower deactivation was found which could result in more open channels at fast rates. The results suggest that the equine K V 7.1/KCNE1 channel may be important for cardiac repolarization and this could indicate that horses are susceptible to SCD caused by mutations in KCNQ1 and KCNE1. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Kcne2 Deletion Creates a Multisystem Syndrome Predisposing to Sudden Cardiac Death

    PubMed Central

    Hu, Zhaoyang; Kant, Ritu; Anand, Marie; King, Elizabeth C.; Krogh-Madsen, Trine; Christini, David J.; Abbott, Geoffrey W.

    2014-01-01

    Background Sudden cardiac death (SCD) is the leading global cause of mortality, exhibiting increased incidence in diabetics. Ion channel gene perturbations provide a well-established ventricular arrhythmogenic substrate for SCD. However, most arrhythmia susceptibility genes - including the KCNE2 K+ channel β subunit - are expressed in multiple tissues, suggesting potential multiplex SCD substrates. Methods and Results Using “whole transcript” transcriptomics, we uncovered cardiac angiotensinogen upregulation and remodeling of cardiac angiotensinogen interaction networks in P21 Kcne2−/− mouse pups, and adrenal remodeling consistent with metabolic syndrome in adult Kcne2−/− mice. This led to the discovery that Kcne2 disruption causes multiple acknowledged SCD substrates of extracardiac origin: diabetes, hypercholesterolemia, hyperkalemia, anemia and elevated angiotensin II. Kcne2 deletion was also prerequisite for aging-dependent QT prolongation, ventricular fibrillation and SCD immediately following transient ischemia, and fasting-dependent hypoglycemia, myocardial ischemia and atrioventricular block. Conclusions Disruption of a single, widely expressed arrhythmia susceptibility gene can generate a multisystem syndrome comprising manifold electrical and systemic substrates and triggers of SCD. This paradigm is expected to apply to other arrhythmia susceptibility genes, the majority of which encode ubiquitously expressed ion channel subunits or regulatory proteins. PMID:24403551

  1. Distinct perinatal features of the hyperpolarization-activated non-selective cation current Ih in the rat cortical plate

    PubMed Central

    2012-01-01

    Background During neocortical development, multiple voltage- and ligand-gated ion channels are differentially expressed in neurons thereby shaping their intrinsic electrical properties. One of these voltage-gated ion channels, the hyperpolarization-activated cyclic nucleotide-gated (HCN) channel and its current Ih, is an important regulator of neuronal excitability. Thus far, studies on an early Ih appearance in rodent neocortex are missing or conflicting. Therefore, we focused our study on perinatal neocortical Ih and its properties. Results In the perinatal rat neocortex we observed a rapid increase in the number of neurons exhibiting Ih. Perinatal Ih had unique properties: first, a pronounced cAMP sensitivity resulting in a marked shift of the voltage sufficient for half-maximum activation of the current towards depolarized voltages and second, an up to 10 times slower deactivation at physiological membrane potentials when compared to the one at postnatal day 30. The combination of these features was sufficient to suppress membrane resonance in our in silico and in vitro experiments. Although all four HCN subunits were present on the mRNA level we only detected HCN4, HCN3 and HCN1 on the protein level at P0. HCN1 protein at P0, however, appeared incompletely processed. At P30 glycosilated HCN1 and HCN2 dominated. By in silico simulations and heterologous co-expression experiments of a ‘slow’ and a ‘fast’ Ih conducting HCN channel subunit in HEK293 cells, we mimicked most characteristics of the native current, pointing to a functional combination of subunit homo- or heteromeres. Conclusion Taken together, these data indicate a HCN subunit shift initiated in the first 24 hours after birth and implicate a prominent perinatal role of the phylogenetically older HCN3 and/or HCN4 subunits in the developing neocortex. PMID:22694806

  2. Interaction of KCNE subunits with the KCNQ1 K+ channel pore

    PubMed Central

    Panaghie, Gianina; Tai, Kwok-Keung; Abbott, Geoffrey W

    2006-01-01

    KCNQ1 α subunits form functionally distinct potassium channels by coassembling with KCNE ancillary subunits MinK and MiRP2. MinK-KCNQ1 channels generate the slowly activating, voltage-dependent cardiac IKs current. MiRP2-KCNQ1 channels form a constitutively active current in the colon. The structural basis for these contrasting channel properties, and the mechanisms of α subunit modulation by KCNE subunits, are not fully understood. Here, scanning mutagenesis located a tryptophan-tolerant region at positions 338–340 within the KCNQ1 pore-lining S6 domain, suggesting an exposed region possibly amenable to interaction with transmembrane ancillary subunits. This hypothesis was tested using concomitant mutagenesis in KCNQ1 and in the membrane-localized ‘activation triplet’ regions of MinK and MiRP2 to identify pairs of residues that interact to control KCNQ1 activation. Three pairs of mutations exerted dramatic effects, ablating channel function or either removing or restoring control of KCNQ1 activation. The results place KCNE subunits close to the KCNQ1 pore, indicating interaction of MiRP2-72 with KCNQ1-338; and MinK-59,58 with KCNQ1-339, 340. These data are consistent either with perturbation of the S6 domain by MinK or MiRP2, dissimilar positioning of MinK and MiRP2 within the channel complex, or both. Further, the results suggest specifically that two of the interactions, MiRP2-72/KCNQ1-338 and MinK-58/KCNQ1-340, are required for the contrasting gating effects of MinK and MiRP2. PMID:16308347

  3. Electron Irradiation of Kuiper Belt Surface Ices: Ternary N2-CH4-CO Mixtures as a Case Study

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    The space weathering of icy Kuiper Belt Objects was investigated in this case study by exposing methane (CH4) and carbon monoxide (CO) doped nitrogen (N2) 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 N2-CH4 and CO-CH4 systems: nitrogen-bearing products were found in the form of hydrogen cyanide (HCN), hydrogen isocyanide (HNC), diazomethane (CH2N2), and its radical fragment (HCN2); oxygen-bearing products were of acetaldehyde (CH3CHO), formyl radical (HCO), and formaldehyde (H2CO). As in the pure ices, the methyl radical (CH3) and ethane (C2H6) were also detected, as were carbon dioxide (CO2) and the azide radical (N3). 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.

  4. Rescue of hyperexcitability in hippocampal CA1 neurons from Mecp2 (-/y) mouse through surface potential neutralization

    PubMed Central

    Mironov, Sergej L.

    2018-01-01

    Hyperventilation is a known feature of Rett syndrome (RTT). However, how hyperventilation is related to other RTT symptoms such as hyperexcitability is unknown. Intense breathing during hyperventilation induces hypocapnia and culminates in respiratory alkalosis. Alkalinization of extracellular milieu can trigger epilepsy in patients who already have neuronal hyperexcitability. By combining patch-clamp electrophysiology and quantitative glutamate imaging, we compared excitability of CA1 neurons of WT and Mecp2 (-/y) mice, and analyzed the biophysical properties of subthreshold membrane channels. The results show that Mecp2 (-/y) CA1 neurons are hyperexcitable in normal pH (7.4) and are increasingly vulnerable to alkaline extracellular pH (8.4), during which their excitability increased further. Under normal pH conditions, an abnormal negative shift in the voltage-dependencies of HCN (hyperpolarization-activated cyclic nucleotide-gated) and calcium channels in the CA1 neurons of Mecp2 (-/y) mice was observed. Alkaline pH also enhanced excitability in wild-type (WT) CA1 neurons through modulation of the voltage dependencies of HCN- and calcium channels. Additionally alkaline pH augmented spontaneous glutamate release and burst firing in WT CA1 neurons. Conversely, acidic pH (6.4) and 8 mM Mg2+ exerted the opposite effect, and diminished hyperexcitability in Mecp2 (-/y) CA1 neurons. We propose that the observed effects of pH and Mg2+ are mediated by changes in the neuronal membrane surface potential, which consecutively modulates the gating of HCN and calcium channels. The results provide insight to pivotal cellular mechanisms that can regulate neuronal excitability and help to devise treatment strategies for hyperexcitability induced symptoms of Rett syndrome. PMID:29621262

  5. Observation of different core water cluster ions Y-(H2O)n (Y = O2, HCN, HOx, NOx, COx) and magic number in atmospheric pressure negative corona discharge mass spectrometry

    NASA Astrophysics Data System (ADS)

    Sekimoto, K.; Takayama, M.

    2010-12-01

    -lived core ions HCN-, NOx- and COx- were mainly produced at higher field strength. Furthermore, the use of the discharge system coupled to mass spectrometers led to the stable formation of large water clusters Y-(H2O)n due to adiabatic expansion caused by the pressure difference between the ambient discharge area (760 torr) and vacuum region in the mass spectrometers (≈ 1 torr). Here we show the resulting mass spectra of large water clusters Y-(H2O)n (0 ≤ n ≥ 80) with the dominant negative core ion Y- such as O2-, HO-, HO2-, HCN-, NO2-, NO3-, NO3-(HNO3)2, CO3- and HCO4- which play a central role in tropospheric ion chemistry, as well as the detailed mechanism of formation of those negative ion water clusters by atmospheric pressure DC corona discharge mass spectrometry. Here we also provide new thermochemical information about magic numbers and first hydrated shells for individual negative core ions Y-, which have particular stability in the Y-(H2O)n cluster series, by using the reliable mass spectrometry data obtained and the relationship between the temperature condition in a reaction chamber and the resulting cluster distribution.

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

    PubMed

    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.

  7. Kcne3 deletion initiates extracardiac arrhythmogenesis in mice

    PubMed Central

    Hu, Zhaoyang; Crump, Shawn M.; Anand, Marie; Kant, Ritu; Levi, Roberto; Abbott, Geoffrey W.

    2014-01-01

    Mutations in the human KCNE3 potassium channel ancillary subunit gene are associated with life-threatening ventricular arrhythmias. Most genes underlying inherited cardiac arrhythmias, including KCNE3, are not exclusively expressed in the heart, suggesting potentially complex disease etiologies. Here we investigated mechanisms of KCNE3-linked arrhythmogenesis in Kcne3−/− mice using real-time qPCR, echo- and electrocardiography, ventricular myocyte patch-clamp, coronary artery ligation/reperfusion, blood analysis, cardiac synaptosome exocytosis, microarray and pathway analysis, and multitissue histology. Kcne3 transcript was undetectable in adult mouse atria, ventricles, and adrenal glands, but Kcne3−/− mice exhibited 2.3-fold elevated serum aldosterone (P=0.003) and differentially expressed gene networks consistent with an adrenal-targeted autoimmune response. Furthermore, 8/8 Kcne3−/− mice vs. 0/8 Kcne3+/+ mice exhibited an activated-lymphocyte adrenal infiltration (P=0.0002). Kcne3 deletion also caused aldosterone-dependent ventricular repolarization delay (19.6% mean QTc prolongation in females; P<0.05) and aldosterone-dependent predisposition to postischemia arrhythmogenesis. Thus, 5/11 Kcne3−/− mice vs. 0/10 Kcne3+/+ mice exhibited sustained ventricular tachycardia during reperfusion (P<0.05). Kcne3 deletion is therefore arrhythmogenic by a novel mechanism in which secondary hyperaldosteronism, associated with an adrenal-specific lymphocyte infiltration, impairs ventricular repolarization. The findings highlight the importance of considering extracardiac pathogenesis when investigating arrhythmogenic mechanisms, even in inherited, monogenic channelopathies.—Hu, Z., Crump, S. M., Anand, M., Kant, R., Levi, R., Abbott, G. W. Kcne3 deletion initiates extracardiac arrhythmogenesis in mice. PMID:24225147

  8. ALMA Multiple-transition Observations of High-density Molecular Tracers in Ultraluminous Infrared Galaxies

    NASA Astrophysics Data System (ADS)

    Imanishi, Masatoshi; Nakanishi, Kouichiro; Izumi, Takuma

    2018-04-01

    We present the results of our ALMA observations of 11 (ultra)luminous infrared galaxies ((U)LIRGs) at J = 4–3 of HCN, HCO+, and HNC and J = 3–2 of HNC. This is an extension of our previously published HCN and HCO+ J = 3–2 observations to multiple rotational J-transitions of multiple molecules, to investigate how molecular emission line flux ratios vary at different J-transitions. We confirm that ultraluminous infrared galaxies (ULIRGs) that contain or may contain luminous obscured active galactic nuclei (AGNs) tend to show higher HCN-to-HCO+ flux ratios than starburst galaxies, both at J = 4–3 and J = 3–2. For selected HCN-flux-enhanced AGN-important ULIRGs, our isotopologue H13CN, H13CO+, and HN13C J = 3–2 line observations suggest a higher abundance of HCN than HCO+ and HNC, which is interpreted to be primarily responsible for the elevated HCN flux in AGN-important galaxies. For such sources, the intrinsic HCN-to-HCO+ flux ratios after line opacity correction will be higher than the observed ratios, making the separation between AGNs and starbursts even larger. The signature of the vibrationally excited (v 2 = 1f) HCN J = 4–3 emission line is seen in one ULIRG, IRAS 12112‑0305 NE. P Cygni profiles are detected in the HCO+ J = 4–3 and J = 3–2 lines toward IRAS 15250+3609, with an estimated molecular outflow rate of ∼250–750 M ⊙ yr‑1. The SiO J = 6–5 line also exhibits a P Cygni profile in IRAS 12112+0305 NE, suggesting the presence of shocked outflow activity. Shock tracers are detected in many sources, suggesting ubiquitous shock activity in the nearby ULIRG population.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gicquel, A.; Villanueva, G. L.; Cordiner, M. A.

    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 Jamesmore » 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).« less

  10. Different roles for the cyclic nucleotide binding domain and amino terminus in assembly and expression of hyperpolarization-activated, cyclic nucleotide-gated channels.

    PubMed

    Proenza, Catherine; Tran, Neil; Angoli, Damiano; Zahynacz, Kristin; Balcar, Petr; Accili, Eric A

    2002-08-16

    In mammalian heart and brain, pacemaker currents are produced by hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels, which probably exist as heteromeric assemblies of different subunit isoforms. To investigate the molecular domains that participate in assembly and membrane trafficking of HCN channels, we have used the yeast two-hybrid system, patch clamp electrophysiology, and confocal microscopy. We show here that the N termini of the HCN1 and HCN2 isoforms interacted and were essential for expression of functional homo- or heteromeric channels on the plasma membrane of Chinese hamster ovary cells. We also show that the cyclic nucleotide binding domain (CNBD) of HCN2 was required for the expression of functional homomeric channels. This expression was dependent on a 12-amino acid domain corresponding to the B-helix in the CNBD of the catabolite activator protein. However, co-expression with HCN1 of an HCN2 deletion mutant lacking the CNBD rescued surface immunofluorescence and currents, indicating that a CNBD need not be present in each subunit of a heteromeric HCN channel. Furthermore, neither CNBDs nor other COOH-terminal domains of HCN1 and HCN2 interacted in yeast two-hybrid assays. Thus, interaction between NH(2)-terminal domains is important for HCN subunit assembly, whereas the CNBD is important for functional expression, but its absence from some subunits will still allow for the assembly of functional channels.

  11. Structural basis for KCNE3 modulation of potassium recycling in epithelia.

    PubMed

    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."

  12. Characterization of the Minimum Energy Path for the Reaction of Singlet Methylene with N2: The Role of Singlet Methylene in Prompt NO

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.

    1995-01-01

    We report calculations of the minimum energy pathways connecting (1)CH2+N2 to diazomethane and diazirine, for the rearrangement of diazirine to diazomethane, for the dissociation of diazirine to HCN2+H, and of diazomethane to CH2N+N. The calculations use complete active space self-consistent field (CASSCF) derivative methods to characterize the stationary points and internally contracted configuration interaction (ICCI) to determine the energetics. The calculations suggest a potential new source of prompt NO from the reaction of (1)CH2 with N2 to give diazirine, and subsequent reaction of diazirine with hydrogen abstracters to form doublet HCN2, which leads to HCN+N(S-4) on the previously studied CH+N2 Surface. The calculations also predict accurate 0 K heats of formation of 77.7 kcal/mol and 68.0 kcal/mol for diazirine and diazomethane, respectively.

  13. Spectrophotometry and organic matter on Iapetus. 1: Composition models

    NASA Technical Reports Server (NTRS)

    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.

  14. Long QT syndrome type 5-Lite: Defining the clinical phenotype associated with the potentially proarrhythmic p.Asp85Asn-KCNE1 common genetic variant.

    PubMed

    Lane, Conor; Giudicessi, John R; Ye, Dan; Tester, David J; Rohatgi, Ram K; Bos, J Martijn; Ackerman, Michael J

    2018-04-03

    Long QT syndrome (LQTS) genetic test reports commonly exclude potentially proarrhythmic common variants such as p.Asp85Asn-KCNE1. The purpose of this study was to determine whether a discernible phenotype is associated with p.Asp85Asn-KCNE1 and whether relatively common KCNE1 variants underlie transient QT prolongation pedigrees with negative commercial LQTS genetic tests. Retrospective review was used to compare demographics, symptomatology, and QT parameters of individuals with p.Asp85Asn-KCNE1 in the absence of other rare/ultra-rare variants in LQTS-susceptibility genes and those who underwent comprehensive LQTS genetic testing. Compared to the Genome Aggregation Database, p.Asp85Asn-KCNE1 was more prevalent in individuals undergoing LQTS genetic testing (33/1248 [2.6%] vs 1552/126,652 [1.2%]; P = .0001). In 19 of 33 patients (58%), only p.Asp85Asn-KCNE1 was observed. These patients were predominantly female (90% vs 62%; P = .02) and were less likely to experience syncope (0% vs 34%; P = .0007), receive β-blockers (53% vs 85%; P = .001), or require an implantable cardioverter-defibrillator (5.3% vs 33%; P = .01). However, they exhibited a similar degree of QT prolongation (QTc 460 ms vs 467 ms; P = NS). Whole exome sequencing of 2 commercially genotype-negative pedigrees revealed that p.Asp85Asn-KCNE1 and p.Arg36His-KCNE1 traced with a transient QT prolongation phenotype. Functional characterization of p.Arg36His-KCNE1 demonstrated loss of function, with a 47% reduction in peak I Ks current density in the heterozygous state. We provide further evidence that relatively common variants in KCNE1 may result in a mild QT phenotype designated as "LQT5-Lite" to distinguish such potentially proarrhythmic common variants (ie, functional risk alleles) from rare pathogenic variants that truly confer monogenic disease susceptibility, albeit with incomplete penetrance. Copyright © 2018. Published by Elsevier Inc.

  15. A conserved domain in the NH2 terminus important for assembly and functional expression of pacemaker channels.

    PubMed

    Tran, Neil; Proenza, Catherine; Macri, Vincenzo; Petigara, Fiona; Sloan, Erin; Samler, Shannon; Accili, Eric A

    2002-11-15

    Pacemaker channels are formed by co-assembly of hyperpolarization-activated cyclic nucleotide-gated (HCN) subunits. Previously, we suggested that the NH(2) termini of the mouse HCN2 isoform were important for subunit co-assembly and functional channel expression. Using an alignment strategy together with yeast two-hybrid assays, patch clamp electrophysiology, and confocal imaging, we have now identified a domain within the NH(2) terminus of the HCN2 subunit that is responsible for interactions between NH(2) termini and promoting the trafficking of functional channels to the plasma membrane. This domain is composed of 52 amino acids, is located adjacent to the putative first transmembrane segment, and is highly conserved among the mammalian HCN isoforms. This conserved domain, but not the remaining unconserved NH(2)-terminal regions of HCN2, specifically interacted with itself in yeast two-hybrid assays. Moreover, the conserved domain was important for expression of currents. Whereas relatively normal whole cell HCN2 currents were produced by channels containing only the conserved domain, further deletion of this region, leaving only a more polar and putative coiled-coil segment, eliminated HCN2 currents and resulted in proteins that localized predominantly in perinuclear compartments. Thus, we suggest that this conserved domain is the critical NH(2)-terminal determinant of subunit co-assembly and trafficking of pacemaker channels.

  16. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kim, S.; Sorescu, D.C.; Yates, J.T., Jr.

    The adsorption and vibrational properties of chemisorbed HCN on Lewis acid sites, Lewis base sites, and Brønsted Al-OH acid sites on a partially hydroxylated [gamma]-Al2O3 surface have been obtained by a combination of FTIR and density functional theory studies. The vibrational modes from the molecular and dissociative adsorption of HCN were assigned by using deuterium and 13C-labeled D13CN molecules at 170 K. In addition, [eta]2(C, N)-HCN bonding is also found from the [nu](CdN) vibrational spectra. Good correlation of the calculated vibrational frequencies for the adsorbed species with experimental data is found. The effect of triethylenediamine (TEDA) (also called 1, 4-diazabicyclomore » [2.2.2]octane, DABCO) on the adsorption of hydrogen cyanide (HCN) on the high area [gamma]-Al2O3 surface has been investigated using transmission FTIR spectroscopy. During HCN adsorption on TEDA-functionalized surfaces, there is no spectral change or emerging feature in either the TEDA or HCN spectral regions, indicating that no direct interaction occurs between these two molecules. Instead, we found that TEDA competes with HCN for the active sites on [gamma]-Al2O3. The observed [nu](C [identical with] N) mode on a TEDA-precovered surface is due to the HCN adsorption on Lewis base sites (Al-O-Al) which are less affected by TEDA preadsorption.« less

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

    PubMed

    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

  18. The Dense Molecular Gas and Nuclear Activity in the ULIRG IRAS 13120-5453

    NASA Astrophysics Data System (ADS)

    Privon, G. C.; Aalto, S.; Falstad, N.; Muller, S.; González-Alfonso, E.; Sliwa, K.; Treister, E.; Costagliola, F.; Armus, L.; Evans, A. S.; Garcia-Burillo, S.; Izumi, T.; Sakamoto, K.; van der Werf, P.; Chu, J. K.

    2017-02-01

    We present new Atacama Large Millimeter/submillimeter Array Band 7 (˜340 GHz) observations of the dense gas tracers HCN, HCO+, and CS in the local, single-nucleus, ultraluminous infrared galaxy IRAS 13120-5453. We find centrally enhanced HCN (4-3) emission, relative to HCO+ (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-1, the high HCN/HCO+ 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 ΣIR of 4.7 × 1012 L ⊙ kpc-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 H2O lines and find a nuclear dust temperature of ˜40 K. IRAS 13120-5453 has a lower dust temperature and ΣIR 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Diagnostic studies of H2 Ar N2 microwave plasmas containing methane or methanol using tunable infrared diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Hempel, F.; Davies, P. B.; Loffhagen, D.; Mechold, L.; Röpcke, J.

    2003-11-01

    Tunable infrared diode laser absorption spectroscopy has been used to detect the methyl radical and nine stable molecules, CH4, CH3OH, C2H2, C2H4, C2H6, NH3, HCN, CH2O and C2N2, in H2-Ar-N2 microwave plasmas containing up to 7% of methane or methanol, under both flowing and static conditions. The degree of dissociation of the hydrocarbon precursor molecules varied between 20% and 97%. The methyl radical concentration was found to be in the range 1012-1013 molecules cm-3. By analysing the temporal development of the molecular concentrations under static conditions it was found that HCN and NH3 are the final products of plasma chemical conversion. The fragmentation rates of methane and methanol (RF(CH4) = (2-7) × 1015 molecules J-1, RF(CH3OH) = (6-9) × 1015 molecules J-1) and the respective conversion rates to methane, hydrogen cyanide and ammonia (RCmax(CH4) = 1.2 × 1015 molecules J-1, RCmax(HCN) = 1.3 × 1015 molecules J-1, RCmax(NH3) = 1 × 1014 molecules J-1) have been determined for different hydrogen to nitrogen concentration ratios. An extensive model of the chemical reactions involved in the H2-N2-Ar-CH4 plasma has been developed. Model calculations were performed by including 22 species, 145 chemical reactions and appropriate electron impact dissociation rate coefficients. The results of the model calculations showed satisfactory agreement between calculated and measured concentrations. The most likely main chemical pathways involved in these plasmas are discussed and an appropriate reaction scheme is proposed.

  1. On the Stratospheric Chemistry of Hydrogen Cyanide

    NASA Technical Reports Server (NTRS)

    Kleinbohl, Armin; Toon, Geoffrey C.; Sen, Bhaswar; Blavier, Jean-Francois L.; Weisenstein, Debra K.; Strekowski, Rafal S.; Nicovich, J. Michael; Wine, Paul H.; Wennberg, Paul O.

    2006-01-01

    HCN profiles measured by solar occultation spectrometry during 10 balloon flights of the JPL MkIV instrument are presented. The HCN profiles reveal a compact correlation with stratospheric tracers. Calculations with a 2D-model using established rate coefficients for the reactions of HCN with OH and O(1D) severely underestimate the measured HCN in the middle and upper stratosphere. The use of newly available rate coefficients for these reactions gives reasonable agreement of measured and modeled HCN. An HCN yield of approx.30% from the reaction of CH3CN with OH is consistent with the measurements.

  2. 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

    NASA Technical Reports Server (NTRS)

    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.; hide

    2016-01-01

    We report production rates for H2O and eight trace molecules (CO, C2H6, CH4, CH3OH, NH3, H2CO, HCN, C2H2) in the dynamically new, Sun-grazing Comet C2012 S1 (ISON), using high-resolution spectroscopy at Keck II and the NASA IRTF on 10pre-perihelion dates encompassing heliocentric distances Rh1.210.34 AU. Measured water production rates spanned two orders of magnitude, consistent with a long-term heliocentric power law Q(H2O) Rh-3.10.1). Abundance ratios for CO, C2H6, and CH4 with respect to H2O remained constant with Rh and below their corresponding mean values measured among a dominant sample of Oort Cloud comets. CH3OH was also depleted for Rh 0.5 AU, but was closer to its mean value for Rh0.5 AU. The remaining four molecules exhibited higher abundance ratios within 0.5 AU: for Rh 0.8 AU, NH3 and C2H2 were consistent with their mean values while H2CO and HCN were depleted. For Rh 0.5 AU, all four were enriched, with NH3, H2CO, and HCN increasing most. Spatial profiles of gas emission in ISON consistently peaked sunward of the dust continuum, which was asymmetric antisunward and remained singly peaked for all observations. NH3 within 0.5 AU showed a broad spatial distribution, possibly indicating its release in the coma provided that optical depth effects were unimportant. The column abundance ratio NH2H2O at 0.83 AU was close to the typical NHOH from optical wavelengths, but was higher within 0.5 AU. Establishing its production rate and testing its parentage (e.g., NH3) require modeling of coma outflow.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Privon, G. C.; Treister, E.; Aalto, S.

    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 maymore » 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.« less

  4. A Molecular Toolbox for Rapid Generation of Viral Vectors to Up- or Down-Regulate Neuronal Gene Expression in vivo

    PubMed Central

    White, Melanie D.; Milne, Ruth V. J.; Nolan, Matthew F.

    2011-01-01

    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 miRNA). We show that AAV assembled to express HCN1 miRNA produces efficacious and specific in vivo knockdown of HCN1 channels. Comparison of in vivo viral transduction using HCN1 miRNA 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. PMID:21772812

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

    NASA Astrophysics Data System (ADS)

    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

  6. The Coupled Photochemistry of Ammonia and Acetylene: Applications to the Atmospheric Chemistry on Jupiter

    NASA Astrophysics Data System (ADS)

    Keane, Thomas Christopher

    1995-01-01

    The existence of hydrogen cyanide (HCN) in the highly reducing atmosphere of Jupiter was a surprising discovery (Tokunaga et al., 1981). Previous studies that tested the theoretical proposal of Kaye and Strobel (1983a) that the HCN observed on Jupiter is the result of NH _3 photolysis in the presence of C _2H_2 established that acetonitrile (CH_3CN) and acetaldazine (CH _3CH=NN=CHCH_3) are important intermediates in HCN formation (Ferris and Ishikawa, 1988). In this study the rates of formation of these compounds, and of other recently detected intermediates, have been determined in static photolysis experiments at 296 K and at temperatures which are closer to those found in the Jovian atmosphere. Experiments were also performed, using a photochemical flow reactor, that allowed for a better approximation of the mixing ratios of reactant gases (8 times 10^{ -4} for NH_3 and 1 times 10^{-5} for C_2H_2) and the process of advection in the Jovian atmosphere. An overall reaction pathway for HCN formation is proposed. Major intermediates and products found in these laboratory simulations that have not yet been observed on Jupiter are acetonitrile (CH_3CN), acetaldazine (CH_3CH=NN=CHCH _3), acetaldehyde hydrazone (CH_3 CH=NNH_2), N-ethylethylideneimine (CH_3CH=NC_2H _5), ethylamine (C_2H _5NH_2) and methylamine (CH _3NH_2). HCN is formed by the photolysis of NH_3/C _2H_2 mixtures (40:5 torr) at 296 K and at low temperature (208 K, 195 K and 180 K) with the highest quantum efficiency for HCN formation observed at 180 K. In static experiments using a high partial pressure of H_2 the quantum yield for HCN formation decreased three-fold relative to the 296 K photolyses when no H_2 was used. An additional ten-fold decrease in the quantum yield for HCN formation occurred when using the flow system. The quantum yields for acetaldazine and acetaldehyde hydrazone formation were found to vary inversely to that for HCN formation. For those static experiments which best simulate

  7. Search for Extraterrestrial Origin of Atmospheric Trace Molecules Radio Sub-MM Observations During The Leonids

    NASA Technical Reports Server (NTRS)

    Depois, D.; Ricaud, P.; Lautie, N.; Schneider, N.; Jacq, T.; Biver, N.; Lis, D.; Chamberlain, R.; Phillips, T.; Miller, M.; hide

    2000-01-01

    HCN is a minor constituent of the Earth atmosphere, with a typical volume mixing ratio around 10(exp -10) HCN per air molecule. At present, the main source of HCN in the lower atmosphere is expected to be biomass burning. The atmospheric HCN has been observed since 1981, first in the infrared, then at microwave radio frequencies. Globally, above 30 km, HCN measurements are in excess of model predictions based on standard photochemistry and biomass burning as the only HCN source. This excess has been explained by: 1) ion-catalyzed reactions in the entire stratosphere, involving CH.3CN as a precursor and/or 2) a high altitude source as a result of chemical production from the methyl radical CH3, or from injection or production by meteors. HCN is a minor constituent of cometary ices. HCN polymers or copolymers have been suggested as constituents of cometary refractory organic matter, and would thus be present in the incoming meteoroids, if these polymers survived their stay in interplanetary space after ejection. HCN may also be created from the CN radical decomposition product of organic carbon, after reaction with hydrogen-bearing molecules. To test the hypothesis of HCN input by meteoroids or the formation in the upper atmosphere from meteoric ablation products, we decided to monitor the HCN submillimeter lines around a major shower: the Leonids.

  8. Expression of key ion channels in the rat cardiac conduction system by laser capture microdissection and quantitative real-time PCR.

    PubMed

    Ou, Yan; Niu, Xiao-lin; Ren, Fu-xian

    2010-09-01

    The objective of this study was to investigate the molecular basis of the inferior nodal extension (INE) in the atrioventricular junctional area that accounts for arrhythmias. The INE was separated from the adult rat heart by laser capture microdissection. The mRNA expression of ion channels was detected by quantitative real-time PCR. Hierarchical clustering was used to demonstrate clustering of expression of genes in sections. The mRNA expression of HCN4, Ca(v)3.1 and Ca(v)3.2 was high in the INE, atrioventricular node and sino-atrial node, and that of Ca(v)3.2 high in Purkinje fibres. Although the expression of HCN1 and Ca(v)1.3 was low in the rat heart, it was relatively higher in the INE, atrioventricular node and sino-atrial node than in right atrial and right ventricular (working) myocytes. Both HCN2 and Ca(v)1.2 were expressed at higher levels in working myocytes than in nodal tissues and in the INE. Hierarchical clustering analysis demonstrated that the expression of the HCN and calcium channels in INE was similar to that in the slow-response automatic cells and different from that in working myocytes and Purkinje fibres. The expression of HCN and calcium channels in the INE of the adult rat heart is similar to that of slow-response automatic cells and provides a substrate for automatic phase 4 depolarization in cells.

  9. Characterization of the Minimum Energy Path for the Reaction of Singlet Methylene with N2: The Role of Singlet Methylene in Prompt NO

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.

    1995-01-01

    We report calculations of the minimum energy pathways connecting CH2 + N2 to diazomethane and diazirine, for the rearrangement of diazirine to diazomethane, for the dissociation of diazirine to HCN2+H, and of diazomethane to CH2N+N. The calculations use Complete Active Space Self-Consistent Field (CASSCF) derivative methods to characterize the stationary points and Internally Contracted Configuration Interaction (ICCI) to determine the energetics. The calculations suggest a potential new source of prompt NO from the reaction CH2 with N2 to give diazirine, and subsequent reaction of diazirine with hydrogen abstracters to form doublet HCN2, which leads to HCN+N(S-4) on the previously studied CH+N2 surface. The calculations also predict accurate 0 K heats of formation of 77.7 kcal/mol and 68.0 kcal/mol for diazirine and diazomethane, respectively.

  10. Multiconfiguration Self-Consistent Field Study on Formonitrile Imine and N-Substituted Nitrile Imines HCN2-R: Energy Component Analysis of the Pseudo-Jahn-Teller Effect.

    PubMed

    Toyota, Azumao; Muramatsu, Takashi; Koseki, Shiro

    2017-03-23

    Stable geometrical structures for formonitrile imine (1) and N-substituted nitrile imines HCN 2 -R (R = Li, BeH, BH 2 , CH 3 , CN, CCH, C 6 H 5 , NH 2 , OH, and F) (2-11) were examined by using the multiconfiguration self-consistent-field (MCSCF) method followed by second-order configuration interaction (SOCI) calculations and second-order multiconfiguration quasi-degenerate perturbation theory (MCQDPT2) calculations, together with the aug-cc-pVTZ basis sets. The results show that 1 suffers a pseudo-Jahn-Teller (JT) distortion from a linear C ∞v structure to a C 1 structure via a planar bent C s structure. Each of the others is found to undergo pseudo-JT distortion from a symmetrical structure to a planar bent C s structure for 2, 3, and 7 and to a C 1 structure for 4, 5, 6, 8, 9, 10, and 11. At the stationary structures of 1-11, the structural characteristics were briefly discussed in terms of allenic and propargylic. To elucidate the nature of pseudo-JT distortions, energy component analyses were carried out at the MCSCF+SOCI level of theory at all of the stationary structures for the relevant molecules. In most of the molecules examined, pseudo-JT stabilizations were classified into two groups, one in which the stability arises from a lowering of the energy of the attractive term V en and the other in which the stability results from a lowering of the energy of the repulsive terms V nn and V ee . In addition to the above two groups, it was also found that the following three groups are responsible for the pseudo-JT stabilizations in a certain stage of the structural changes. Namely, one is a lowering of the energy of the term V ee observed in 6, another is a lowering of the energy of the terms V ee and V en observed in 9-11, and the other is a lowering of the energy of the terms V en and V nn observed in 10. These energetic behaviors were accounted in terms of an elongation or a contraction of the molecular skeleton, a migration of electrons from one part of

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

    NASA Technical Reports Server (NTRS)

    Roth, Nathan X.; Gibb, Erika; Bonev, Boncho P.; Disanti, Michael A.; Mumma, Michael J.; Villanueva, Geronimo L.; Paganini, Lucas

    2017-01-01

    On 2014 May 22 and 24 we characterized the volatile composition of the dynamically new Oort cloud comet C2012 K1 (PanSTARRS) using the long-slit, high resolution ( lambda/delta lambda is approximately or equal to 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 (H2O, HCN, CH4, C2H6, CH3OH, and CO). Upper limits were derived for C2H2, NH3, and H2CO. 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 C2012 K1 (PanSTARRS) for CO and HCN are consistent, but CH3OH and C2H6 are enriched while H2CO, CH4, and possibly C2H2 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, C2H6, CH3OH, CH4) 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.

  12. Characteristics and physiological role of hyperpolarization activated currents in mouse cold thermoreceptors

    PubMed Central

    Orio, Patricio; Madrid, Rodolfo; de la Peña, Elvira; Parra, Andrés; Meseguer, Víctor; Bayliss, Douglas A; Belmonte, Carlos; Viana, Félix

    2009-01-01

    Hyperpolarization-activated currents (Ih) are mediated by the expression of combinations of hyperpolarization-activated, cyclic nucleotide-gated (HCN) channel subunits (HCN14). These cation currents are key regulators of cellular excitability in the heart and many neurons in the nervous system. Subunit composition determines the gating properties and cAMP sensitivity of native Ih currents. We investigated the functional properties of Ih in adult mouse cold thermoreceptor neurons from the trigeminal ganglion, identified by their high sensitivity to moderate cooling and responsiveness to menthol. All cultured cold-sensitive (CS) neurons expressed a fast activating Ih, which was fully blocked by extracellular Cs+ or ZD7288 and had biophysical properties consistent with those of heteromeric HCN1HCN2 channels. In CS neurons from HCN1(−/−) animals, Ih was greatly reduced but not abolished. We find that Ih activity is not essential for the transduction of cold stimuli in CS neurons. Nevertheless, Ih has the potential to shape the excitability of CS neurons. First, Ih blockade caused a membrane hyperpolarization in CS neurons of about 5 mV. Furthermore, impedance power analysis showed that all CS neurons had a prominent subthreshold membrane resonance in the 5–7 Hz range, completely abolished upon blockade of Ih and absent in HCN1 null mice. This frequency range matches the spontaneous firing frequency of cold thermoreceptor terminals in vivo. Behavioural responses to cooling were reduced in HCN1 null mice and after peripheral pharmacological blockade of Ih with ZD7288, suggesting that Ih plays an important role in peripheral sensitivity to cold. PMID:19273581

  13. Hydrogen cyanide as a biomarker for Pseudomonas aeruginosa in the breath of children with cystic fibrosis.

    PubMed

    Enderby, Beth; Smith, David; Carroll, W; Lenney, W

    2009-02-01

    Hydrogen cyanide (HCN) is emitted by Pseudomonas aeruginosa (PA) in vitro. We hypothesized that exhaled HCN could be measured using Selected Ion Flow Tube Mass Spectrometry (SIFT-MS) and that concentrations would be higher in children with cystic fibrosis (CF) and PA infection than in children with asthma. Children aged 7-17 years with CF (n = 16) or asthma (n = 21) attending outpatient clinics provided breath samples between July and December 2007. HCN was measured using the SIFT-MS Profile 3 instrument. FeNO was measured with a Sievers NOA 280i analyzer. Baseline inter-group differences between HCN and FeNO concentrations were compared using the Mann-Whitney U test. Children were invited to re-attend fortnightly. Breath samples, spirometry, growth and clinical status were measured at each visit. There were significant baseline differences in exhaled HCN and FeNO concentrations between the two groups. Children with CF had higher median HCN concentrations than those with asthma: 13.5 parts per billion (ppb) (IQR 8.1-16.5) versus 2.0 ppb (IQR 0.0-4.8) (P < 0.001). Children with CF had lower median FeNO levels compared to children with asthma: 13.4 ppb (IQR 8.9-17.6) versus 57.9 ppb (IQR 34.0-85.7) (P < 0.001). Intra-subject variability was high and significant changes in HCN concentrations were not observed related to changes in lung function or clinical status. This study provides proof of principle that HCN is detectable in the breath of children with CF and is elevated compared to children with asthma. Further studies are required to capture data from acutely unwell children and more accurately delineate responses to treatment. (c) 2009 Wiley-Liss, Inc.

  14. Dense Gas, Dynamical Equilibrium Pressure, and Star Formation in Nearby Star-forming Galaxies

    NASA Astrophysics Data System (ADS)

    Gallagher, Molly J.; Leroy, Adam K.; Bigiel, Frank; Cormier, Diane; Jiménez-Donaire, María J.; Ostriker, Eve; Usero, Antonio; Bolatto, Alberto D.; García-Burillo, Santiago; Hughes, Annie; Kepley, Amanda A.; Krumholz, Mark; Meidt, Sharon E.; Meier, David S.; Murphy, Eric J.; Pety, Jérôme; Rosolowsky, Erik; Schinnerer, Eva; Schruba, Andreas; Walter, Fabian

    2018-05-01

    We use new ALMA observations to investigate the connection between dense gas fraction, star formation rate (SFR), and local environment across the inner region of four local galaxies showing a wide range of molecular gas depletion times. We map HCN (1–0), HCO+ (1–0), CS (21), 13CO (1–0), and C18O (1–0) across the inner few kiloparsecs of each target. We combine these data with short-spacing information from the IRAM large program EMPIRE, archival CO maps, tracers of stellar structure and recent star formation, and recent HCN surveys by Bigiel et al. and Usero et al. We test the degree to which changes in the dense gas fraction drive changes in the SFR. {I}HCN}/{I}CO} (tracing the dense gas fraction) correlates strongly with I CO (tracing molecular gas surface density), stellar surface density, and dynamical equilibrium pressure, P DE. Therefore, {I}HCN}/{I}CO} becomes very low and HCN becomes very faint at large galactocentric radii, where ratios as low as {I}HCN}/{I}CO}∼ 0.01 become common. The apparent ability of dense gas to form stars, {{{Σ }}}SFR}/{{{Σ }}}dense} (where Σdense is traced by the HCN intensity and the star formation rate is traced by a combination of Hα and 24 μm emission), also depends on environment. {{{Σ }}}SFR}/{{{Σ }}}dense} decreases in regions of high gas surface density, high stellar surface density, and high P DE. Statistically, these correlations between environment and both {{{Σ }}}SFR}/{{{Σ }}}dense} and {I}HCN}/{I}CO} are stronger than that between apparent dense gas fraction ({I}HCN}/{I}CO}) and the apparent molecular gas star formation efficiency {{{Σ }}}SFR}/{{{Σ }}}mol}. We show that these results are not specific to HCN.

  15. Distinct gene-specific mechanisms of arrhythmia revealed by cardiac gene transfer of two long QT disease genes, HERG and KCNE1.

    PubMed

    Hoppe, U C; Marbán, E; Johns, D C

    2001-04-24

    The long QT syndrome (LQTS) is a heritable disorder that predisposes to sudden cardiac death. LQTS is caused by mutations in ion channel genes including HERG and KCNE1, but the precise mechanisms remain unclear. To clarify this situation we injected adenoviral vectors expressing wild-type or LQT mutants of HERG and KCNE1 into guinea pig myocardium. End points at 48-72 h included electrophysiology in isolated myocytes and electrocardiography in vivo. HERG increased the rapid component, I(Kr), of the delayed rectifier current, thereby accelerating repolarization, increasing refractoriness, and diminishing beat-to-beat action potential variability. Conversely, HERG-G628S suppressed I(Kr) without significantly delaying repolarization. Nevertheless, HERG-G628S abbreviated refractoriness and increased beat-to-beat variability, leading to early afterdepolarizations (EADs). KCNE1 increased the slow component of the delayed rectifier, I(Ks), without clear phenotypic sequelae. In contrast, KCNE1-D76N suppressed I(Ks) and markedly slowed repolarization, leading to frequent EADs and electrocardiographic QT prolongation. Thus, the two genes predispose to sudden death by distinct mechanisms: the KCNE1 mutant flagrantly undermines cardiac repolarization, and HERG-G628S subtly facilitates the genesis and propagation of premature beats. Our ability to produce electrocardiographic long QT in vivo with a clinical KCNE1 mutation demonstrates the utility of somatic gene transfer in creating genotype-specific disease models.

  16. Arrhythmogenic KCNE gene variants: current knowledge and future challenges

    PubMed Central

    Crump, Shawn M.; Abbott, Geoffrey W.

    2014-01-01

    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. PMID:24478792

  17. Chemical evolution. XXIX - Pyrimidines from hydrogen cyanide

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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 < 0.05). The mechanical hypersensitivity generated by CFA injection was 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.

  20. ALMA 0.1-0.2 arcsec Resolution Imaging of the NGC 1068 Nucleus: Compact Dense Molecular Gas Emission at the Putative AGN Location

    NASA Astrophysics Data System (ADS)

    Imanishi, Masatoshi; Nakanishi, Kouichiro; Izumi, Takuma

    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+ 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 × 105 M ⊙, respectively. HCN-to-HCO+ 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 2 = 1f) J = 3-2 emission lines were detected for HCN and HCO+ across the field of view.

  1. Linking Dense Gas from the Milky Way to External Galaxies

    NASA Astrophysics Data System (ADS)

    Stephens, Ian W.; Jackson, James M.; Whitaker, J. Scott; Contreras, Yanett; Guzmán, Andrés E.; Sanhueza, Patricio; Foster, Jonathan B.; Rathborne, Jill M.

    2016-06-01

    In a survey of 65 galaxies, Gao & Solomon found a tight linear relation between the infrared luminosity (L IR, a proxy for the star formation rate) and the HCN(1-0) luminosity ({L}{{HCN}}). Wu et al. found that this relation extends from these galaxies to the much less luminous Galactic molecular high-mass star-forming clumps (˜1 pc scales), and posited that there exists a characteristic ratio L IR/{L}{{HCN}} for high-mass star-forming clumps. The Gao-Solomon relation for galaxies could then be explained as a summation of large numbers of high-mass star-forming clumps, resulting in the same L IR/{L}{{HCN}} ratio for galaxies. We test this explanation and other possible origins of the Gao-Solomon relation using high-density tracers (including HCN(1-0), N2H+(1-0), HCO+(1-0), HNC(1-0), HC3N(10-9), and C2H(1-0)) for ˜300 Galactic clumps from the Millimetre Astronomy Legacy Team 90 GHz (MALT90) survey. The MALT90 data show that the Gao-Solomon relation in galaxies cannot be satisfactorily explained by the blending of large numbers of high-mass clumps in the telescope beam. Not only do the clumps have a large scatter in the L IR/{L}{{HCN}} ratio, but also far too many high-mass clumps are required to account for the Galactic IR and HCN luminosities. We suggest that the scatter in the L IR/{L}{{HCN}} ratio converges to the scatter of the Gao-Solomon relation at some size-scale ≳1 kpc. We suggest that the Gao-Solomon relation could instead result from of a universal large-scale star formation efficiency, initial mass function, core mass function, and clump mass function.

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

    PubMed Central

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

    2016-01-01

    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. PMID:26940198

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

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

    2016-03-04

    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.

  5. The Evolution of Volatile Production in Comet C-2009 P1(Garradd) During its 2011-2012 Apparition

    NASA Technical Reports Server (NTRS)

    Gicquel, A.; Milam, S. N.; Coulson, I. M.; Villaneuva, G. L.; Cordiner, M. A.; Charnley, S. B.; DiSanti, M. A.; Mumma, M. J.; Szutowicz, S.

    2015-01-01

    We report observations at millimeter and submillimeter wavelengths of comet C/2009 P1 (Garradd) from 2011 December 28 to 2012 April 24, using the Arizona Radio Observatory submillimeter telescope (SMT) and the James Clerk Maxwell Telescope (JCMT). Garradd is a dynamically young long-period comet from the Oort Cloud, with a periodicity of 127,000 years, that reached perihelion on 2011 December 23 (at Heliocentric distance (Rh) = 1.55 Astronomical Units and delta = 20.1 Astronomical Units ) and made its closest approach to the Earth on 2012 March 05 (at Heliocentric distance (Rh) = 1.84 Astronomical Units and delta = 1.26 Astronomical Units). We obtained gas production rates, and molecular abundances relative to water for HCN, ortho-H2CO, CS, CO and CH3OH. A rotational temperature, T (sub rot) approximately equal to 50 degrees Kelvin, was determined by observing multiple methanol lines with the JCMT. By averaging the abundance ratio relative to water from the SMT and the JCMT we derive: CO: 7.03 plus or minus 1.84 percent, HCN: 0.04 plus or minus 0.01 percent, ortho H2CO: 0.14 plus or minus 0.03 percent as a parent molecule (and 0.28 plus or minus 0.06 percent as an extended source), CS: 0.03 plus or minus 0.01 percent and CH3OH: 3.11 for a range from plus 1:86 to minus 0.51 percent. We concluded that Garradd is normal in CH3OH, depleted in HCN, ortho-H2CO and CS and slightly enriched in CO with respect to typically observed cometary mixing ratios. We also studied the temporal evolution of HCN and CO and find that the production of HCN has a trend similar to water (but with short-term variation), with a decrease after perihelion, while that of CO shows contrary behavior: remaining constant or increasing after perihelion.

  6. IKs channels open slowly because KCNE1 accessory subunits slow the movement of S4 voltage sensors in KCNQ1 pore-forming subunits

    PubMed Central

    Ruscic, Katarina J.; Miceli, Francesco; Villalba-Galea, Carlos A.; Dai, Hui; Mishina, Yukiko; Bezanilla, Francisco; Goldstein, Steve A. N.

    2013-01-01

    Human IKs channels activate slowly with the onset of cardiac action potentials to repolarize the myocardium. IKs channels are composed of KCNQ1 (Q1) pore-forming subunits that carry S4 voltage-sensor segments and KCNE1 (E1) accessory subunits. Together, Q1 and E1 subunits recapitulate the conductive and kinetic properties of IKs. How E1 modulates Q1 has been unclear. Investigators have variously posited that E1 slows the movement of S4 segments, slows opening and closing of the conduction pore, or modifies both aspects of electromechanical coupling. Here, we show that Q1 gating current can be resolved in the absence of E1, but not in its presence, consistent with slowed movement of the voltage sensor. E1 was directly demonstrated to slow S4 movement with a fluorescent probe on the Q1 voltage sensor. Direct correlation of the kinetics of S4 motion and ionic current indicated that slowing of sensor movement by E1 was both necessary and sufficient to determine the slow-activation time course of IKs. PMID:23359697

  7. Hydrogen cyanide in comets - Excitation conditions and radio observations of comet IRAS-Araki-Alcock 1983d

    NASA Technical Reports Server (NTRS)

    Bockelee-Morvan, D.; Crovisier, J.; Baudry, A.; Despois, D.; Perault, M.; Irvine, W. M.; Schloerb, F. P.; Swade, D.

    1984-01-01

    The HCN emission of the pure rotation and rotation/vibration lines in comet IRAS-Araki-Alcock 1983d is examined. The prevailing excitation mechanism for the emissions was the excitation of the nu-2, 2 nu-2, and nu-3 vibrational bands by the solar infrared field. For the description of inner coma, a dynamical excitation model is presented which includes collisions. It is predicted on the basis of the model that HCN molecules in rotation and rotation vibration lines of IRAS-Araki-Alcock 1983d would be detectable with a large-millimeter wave telescope, and that the strongest infrared lines would be observable from space observatories. Subsequent searches for the J = 1-0 HCN radio lines in comet 1983d with the Five College Radio Astronomy Observatory (FCRAO) proved unsuccessful. An extremely low upper limit was found for HCN production which suggests that HCN might not be the only parent of planetary cometary CN.

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

    PubMed

    Andersen, Martin N; Hefting, Louise L; Steffensen, Annette B; Schmitt, Nicole; Olesen, Søren-Peter; Olsen, Jesper V; Lundby, Alicia; Rasmussen, Hanne B

    2015-11-15

    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 slowly activating delayed-rectifier potassium current current, which is enhanced by protein kinase A (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 coassemble 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 led 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 in the observed response. Instead, we found that PKA acted by regulating endocytic trafficking involving the ubiquitin ligase Nedd4-2. We show that a Nedd4-2-resistant Kv7.1-mutant displayed significantly reduced intracellular accumulation upon PKA inhibition. Similar effects were observed upon siRNA knockdown of Nedd4-2. However, although Nedd4-2 is known to regulate Kv7.1 by ubiquitylation, biochemical analyses demonstrated that PKA did not influence the amount of Nedd4-2 bound to Kv7.1 or the ubiquitylation level of the channel. This suggests that PKA influences Nedd4-2-dependent Kv7.1 transport though a different molecular mechanism. In summary, we identify a novel mechanism whereby PKA can increase Kv7.1 current levels, namely by regulating Nedd4-2-dependent Kv7.1 transport. Copyright © 2015 the American Physiological Society.

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

    PubMed Central

    Andersen, Martin N.; Hefting, Louise L.; Steffensen, Annette B.; Schmitt, Nicole; Olesen, Søren-Peter; Olsen, Jesper V.; Lundby, Alicia

    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 slowly activating delayed-rectifier potassium current current, which is enhanced by protein kinase A (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 coassemble 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 led 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 in the observed response. Instead, we found that PKA acted by regulating endocytic trafficking involving the ubiquitin ligase Nedd4-2. We show that a Nedd4-2-resistant Kv7.1-mutant displayed significantly reduced intracellular accumulation upon PKA inhibition. Similar effects were observed upon siRNA knockdown of Nedd4-2. However, although Nedd4-2 is known to regulate Kv7.1 by ubiquitylation, biochemical analyses demonstrated that PKA did not influence the amount of Nedd4-2 bound to Kv7.1 or the ubiquitylation level of the channel. This suggests that PKA influences Nedd4-2-dependent Kv7.1 transport though a different molecular mechanism. In summary, we identify a novel mechanism whereby PKA can increase Kv7.1 current levels, namely by regulating Nedd4-2-dependent Kv7.1 transport. PMID:26405101

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

    NASA Technical Reports Server (NTRS)

    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.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Imanishi, Masatoshi; Nakanishi, Kouichiro; Izumi, Takuma, E-mail: masa.imanishi@nao.ac.jp

    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 molecularmore » 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.« less

  12. Prevalence of hydrogen cyanide and carboxyhaemoglobin in victims of smoke inhalation during enclosed-space fires: a combined toxicological risk.

    PubMed

    Grabowska, Teresa; Skowronek, Rafał; Nowicka, Joanna; Sybirska, Halina

    2012-09-01

    Hydrogen cyanide (HCN) is one of the most toxic components of fire smoke, but insufficient attention is paid to its potential role as a cause of injury or death in victims (alive or dead) of enclosed-space fires. To analyse the prevalence of toxic HCN exposure in fire victims and factors that may influence its toxicity, particularly the co-presence of carbon monoxide (CO) and ethanol. Blood samples from fire victims and persons rescued from fires were analysed. A positive result for HCN (mean concentration 16.83 mg/l) was detected in blood samples from 169 of 285 fire-related deaths (59%). Ethanol was present in 91 (65%) of 139 samples with coincident presence of HCN and carboxyhaemoglobin (COHb). HCN (mean 4.0 mg/l) was also detected in 20 of 40 (50%) fire survivors. The high prevalence of coincident CO and HCN in enclosed-space, fire-related deaths should alert clinicians to suspect toxic HCN exposure in all persons rescued from fire with signs and symptoms of respiratory distress. Medical procedures in persons rescued from enclosed-space fires, especially in the pre-hospital setting, should be augmented to cover the possibility of toxic HCN exposure, particularly in individuals who do not respond to standard supportive therapy. Likewise, post-mortem investigations should routinely include assays for HCN when determining probable cause of death.

  13. Giotto IMS measurements of the production rate of hydrogen cyanide in the coma of Comet Halley

    NASA Technical Reports Server (NTRS)

    Ip, W.-H.; Balsiger, H.; Geiss, J.; Goldstein, B. E.; Kettmann, G.

    1990-01-01

    The ion composition measurements in the ionosphere of Comet Halley by the ion mass spectrometer (IMS) experiment on the Giotto spacecraft are used to estimate the relative abundance of HCN. From a comparison of the normalized number density of ions with mass-to-charge (M/q) ratio of 28 AMU/e with steady-state photochemical models, it can be determined that the production rate of HCN directly from the central nucleus is Q(HCN) is less than about 0.0002 Q(H2O) at the time of Giotto encounter. The related photochemical- model calculations also indicate that Q(NH3)/Q(H2O) at the time of Giotto encounter. The related photo-chemical model calculations also indicate that Q(HN3)/Q(H2O) equals about 0.005, in agreement with recent determination from ground-based observations. The estimated value of Q(HCN) is lower than the relative abundance of Q(HCN)/Q(H2O) of about 0.001, as derived from radio observations of the 88.6 GHz emission of the J = 1 - 0 transition of HCN. The difference may be the result of time variations of the coma composition and dynamics, as well as other model-dependent effects.

  14. Therapeutic effect of astragaloside-IV on bradycardia is involved in up-regulating klotho expression.

    PubMed

    Qiu, Xuejia; Guo, Qiao; Xiong, Wei; Yang, Xia; Tang, Yi-qun

    2016-01-01

    In order to determine whether klotho is involved in the therapeutic effects of Astragaloside-IV on bradycardia, we evaluated the effect of ASG-IV on klotho and the effect of klotho on HCN4 and If. Administrating isoproterenol (5 mg/kg) for 15 days to establish a rat bradycardia model randomized SD rats into control, model (ISO) and ASG-IV (5 mg/kg/day) groups to explore the effect of ASG-IV on klotho. Rats were sacrificed on day 15 after heart rate and heart function were measured; SAN tissues were collected to measure the expression of klotho and HCN4. In vitro, neonatal rat myocardial cells were incubated with LPS for 24 h to inhibit the expression of HCN4 and incubated with LPS+ klotho to explore the effect of klotho on HCN4 expression. We also adopted full-patch-clamp technique to explore the effect of klotho on If. Heart rate in model group was significantly decreased (356.6±19.7 vs. 428.9±19.9 in control group, P<0.01) and ASG-IV can increase heart rate (401.4±12.0 vs. 356.6±19.7 in model group, P<0.01). The expression of klotho was also up-regulated (P<0.05). In vitro, after incubation with LPS for 24h, HCN4 expression was significantly decreased in neonatal rat myocardial cells (0.6±0.07 vs. 1.0, P<0.01) and If was significantly declined. Exogenous klotho showed protective effect on HCN4 expression (1.58±0.16 in ASG-IV group vs. 0.6±0.07 in LPS group, P<0.05) and If. Klotho is involved in the treatment mechanism of ASG-IV. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Nucleus accumbens hyperpolarization-activated cyclic nucleotide-gated channels modulate methamphetamine self-administration in rats.

    PubMed

    Cao, Dan-Ni; Song, Rui; Zhang, Shu-Zhuo; Wu, Ning; Li, Jin

    2016-08-01

    Methamphetamine addiction is believed to primarily result from increased dopamine release and the inhibition of dopamine uptake. Some evidence suggests that hyperpolarization-activated cyclic nucleotide-gated (HCN) channels play important roles in the functional modulation of dopaminergic neurons and the pathophysiology of related diseases. However, little is known about the effects of HCN channels on methamphetamine addiction. The present study investigated the role of brain HCN channels in methamphetamine addiction. Acute intracerebroventricular (i.c.v.) injection or bilateral intra-accumbens microinjections of non-selective HCN channel blocker ZD7288 (0.3125 and 0.625 μg) significantly reduced both methamphetamine (0.0125 or 0.05 mg/kg/infusion)-induced self-administration under fixed ratio 2 reinforcement and the breakpoint of methamphetamine (0.05 mg/kg/infusion) under progressive ratio reinforcement in rats. Moreover, compared with i.c.v. injection, bilateral intra-accumbens microinjections of ZD7288 exerted stronger inhibitory effects, suggesting that blockade of HCN channels in the nucleus accumbens reduced the reinforcing effects of and motivation for methamphetamine. We also found that ZD7288 (0.625 and 1.25 μg, i.c.v.) significantly decreased methamphetamine (1 mg/kg, intraperitoneal (i.p.))-induced hyperactivity with no effect on the spontaneous activity in rats. Finally, in vivo microdialysis experiments showed that the HCN channel blockade using ZD7288 (0.625 and 1.25 μg, i.c.v.) decreased methamphetamine (1 mg/kg, i.p.)-induced elevation of extracellular dopamine levels in the nucleus accumbens. These results indicate that HCN channels in the nucleus accumbens are involved in the reinforcing properties of methamphetamine and highlight the importance of HCN channels in the regulation of dopamine neurotransmission underlying methamphetamine addiction.

  16. SMA observations of the W3(OH) complex: Dynamical differentiation between W3(H2O) and W3(OH)

    NASA Astrophysics Data System (ADS)

    Qin, Sheng-Li; Schilke, Peter; Wu, Jingwen; Liu, Tie; Wu, Yuefang; Sánchez-Monge, Álvaro; Liu, Ying

    2016-03-01

    We present Submillimeter Array observations of the HCN (3-2) and HCO+ (3-2) molecular lines towards the W3(H2O) and W3(OH) star-forming complexes. Infall and outflow motions in the W3(H2O) have been characterized by observing HCN and HCO+ transitions. High-velocity blue/red-shifted emission, tracing the outflow, show multiple knots, which might originate in episodic and precessing outflows. `Blue-peaked' line profiles indicate that gas is infalling on to the W3(H2O) dust core. The measured large mass accretion rate, 2.3 × 10-3 M⊙ yr-1, together with the small free-fall time-scale, 5 × 103 yr, suggest W3(H2O) is in an early evolutionary stage of the process of formation of high-mass stars. For the W3(OH), a two-layer model fit to the HCN and HCO+ spectral lines and Spizter/Infrared Array Camera (IRAC) images support that the W3(OH) H II region is expanding and interacting with the ambient gas, with the shocked neutral gas being expanding with an expansion time-scale of 6.4 × 103 yr. The observations suggest different kinematical time-scales and dynamical states for the W3(H2O) and W3(OH).

  17. Free energy landscape remodeling of the cardiac pacemaker channel explains the molecular basis of familial sinus bradycardia

    PubMed Central

    Boulton, Stephen; Akimoto, Madoka; Akbarizadeh, Sam; Melacini, Giuseppe

    2017-01-01

    The hyperpolarization-activated and cyclic nucleotide-modulated ion channel (HCN) drives the pacemaker activity in the heart, and its malfunction can result in heart disorders. One such disorder, familial sinus bradycardia, is caused by the S672R mutation in HCN, whose electrophysiological phenotypes include a negative shift in the channel activation voltage and an accelerated HCN deactivation. The outcomes of these changes are abnormally low resting heart rates. However, the molecular mechanism underlying these electrophysiological changes is currently not fully understood. Crystallographic investigations indicate that the S672R mutation causes limited changes in the structure of the HCN intracellular gating tetramer, but its effects on protein dynamics are unknown. Here, we utilize comparative S672R versus WT NMR analyses to show that the S672R mutation results in extensive perturbations of the dynamics in both apo- and holo-forms of the HCN4 isoform, reflecting how S672R remodels the free energy landscape for the modulation of HCN4 by cAMP, i.e. the primary cyclic nucleotide modulator of HCN channels. We show that the S672R mutation results in a constitutive shift of the dynamic auto-inhibitory equilibrium toward inactive states of HCN4 and broadens the free-energy well of the apo-form, enhancing the millisecond to microsecond dynamics of the holo-form at sites critical for gating cAMP binding. These S672R-induced variations in dynamics provide a molecular basis for the electrophysiological phenotypes of this mutation and demonstrate that the pathogenic effects of the S672R mutation can be rationalized primarily in terms of modulations of protein dynamics. PMID:28174302

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Theoretical insights into the π-hole interactions in the complexes containing triphosphorus hydride (P3H3) and its derivatives.

    PubMed

    Wang, Yuehong; Li, Xiaoyan; Zeng, Yanli; Meng, Lingpeng; Zhang, Xueying

    2017-04-01

    The π-hole of triphosphorus hydride (P 3 H 3 ) and its derivatives Z 3 X 3 (Z = P, As; X = H, F, Cl, Br) was discovered and analyzed. MP2/aug-cc-pVDZ calculations were performed on the π-hole interactions in the HCN...Z 3 X 3 complexes and the mutual influence between π-hole interactions and the hydrogen bond in the HCN...HCN...Z 3 X 3 and HCN...Z 3 X 3 ...HCN complexes studied. The π-hole interaction belongs to the typical closed-shell noncovalent interaction. The linear relationship was found between the most positive electrostatic potential of the π-hole (V S,max ) and the interaction energy. Moreover, the V S,max of the π-hole was also found to be linearly correlated to the electrostatic energy term, indicating the important contribution of the electrostatic energy term to the π-hole interaction. There is positive cooperativity between the π-hole interaction and the hydrogen bond in the termolecular complexes. The π-hole interaction has a greater influence on the hydrogen bond than vice versa. The mutual enhancing effect between the π-hole interaction and the hydrogen bond in the HCN...HCN...Z 3 X 3 complexes is greater than that in the HCN...Z 3 X 3 ...HCN complexes.

  1. The unbearable opaqueness of Arp220

    NASA Astrophysics Data System (ADS)

    Martín, S.; Aalto, S.; Sakamoto, K.; González-Alfonso, E.; Muller, S.; Henkel, C.; García-Burillo, S.; Aladro, R.; Costagliola, F.; Harada, N.; Krips, M.; Martín-Pintado, J.; Mühle, S.; van der Werf, P.; Viti, S.

    2016-05-01

    Context. The origin of the enormous luminosities of the two opaque nuclei of Arp 220, the prototypical ultra-luminous infrared galaxy, remains a mystery because we lack observational tools to explore the innermost regions around the nuclei. Aims: We explore the potential of imaging vibrationally excited molecular emission at high angular resolution to better understand the morphology and physical structure of the dense gas in Arp 220 and to gain insight into the nature of the nuclear powering sources. Methods: The Atacama Large Millimeter/submillimeter Array (ALMA) provided simultaneous observations of HCN, HCO+, and vibrationally excited HCN v2 = 1f emission. Their J = 4-3 and 3-2 transitions were observed at a matching resolution of ~0.5'', which allows us to isolate the emission from the two nuclei. Results: The HCN and HCO+ lines within the ground-vibrational state poorly describe the central ~100 pc region around the nuclei because there are strong effects of cool absorbing gas in the foreground and severe line blending that is due to the prolific molecular emission of Arp 220. Vibrationally excited emission of HCN is detected in both nuclei with a very high ratio relative to the total LFIR, higher than in any other observed galaxy and well above what is observed in Galactic hot cores. HCN v2 = 1f is observed to be marginally resolved in ~60 × 50 pc regions inside the dusty ~100 pc sized nuclear cores. Its emission is centered on our derived individual nuclear velocities based on HCO+ emission (VWN = 5342 ± 4 and VEN = 5454 ± 8 km s-1, for the western and eastern nucleus, respectively). With virial masses within r ~ 25-30 pc based on the HCN v2 = 1f line widths, we estimate gas surface densities (gas fraction fg = 0.1) of 3 ± 0.3 × 104 M⊙ pc-2 (WN) and 1.1 ± 0.1 × 104 M⊙ pc-2 (EN). The 4-3/3-2 flux density ratio could be consistent with optically thick emission, which would further constrain the size of the emitting region to >15 pc (EN) and >22 pc

  2. Temporal and Spatial Aspects of Gas Release During the 2010 Apparition of Comet 103P/Hartley-2

    NASA Technical Reports Server (NTRS)

    Mumma, M. J.; Bonev, B. P.; Villanueva, G. L.; Paganini, L.; DiSanti, M. A.; Gibb, E. L.; Keane, J. V.; Meech, K. J.; Blake, G. A.; Ellis, R. S.; hide

    2011-01-01

    We report measurements of eight primary volatiles (H2O, HCN, CH4, C2H6, CH3OH, C2H2, H2CO, and NH3) and two product species (OH and NH2) in comet lO3P/Hartley-2 using high dispersion infrared spectroscopy. We quantified the long- and short-term behavior of volatile release over a three-month interval that encompassed the comet's close approach to Earth, its perihelion passage, and flyby of the comet by the Deep Impact spacecraft during the EPOXI mission. We present production rates for individual species, their mixing ratios relative to water, and their spatial distributions in the coma on multiple dates. The production rates for water, ethane, HCN, and methanol vary in a manner consistent with independent measures of nucleus rotation, but mixing ratios for HCN, C2H6, & CH3OH are independent of rotational phase. Our results demonstrate that the ensemble average composition of gas released from the nucleus is well defined, and relatively constant over the three-month interval (September 18 through December 1,7). If individual vents vary in composition, enough diverse vents must be active simultaneously to approximate (in sum) the bulk composition of the nucleus. The released primary volatiles exhibit diverse spatial properties which favor the presence of separate polar and apolar ice phases in the nucleus, establish dust and gas release from icy clumps, and from the nucleus, and provide insights into the driver for the cyanogen (CN) polar jet. The spatial distributions of C2H6 & HCN along the near-polar jet (UT 19.5 October) and nearly orthogonal to it (UT 22.5 October) are discussed relative to the origin of CN. The ortho-para ratio (OPR) of water was 2.85 +/- 0.20; the lower bound (2.65) defines T(sub spin) > 32 K. These values are consistent with results returned from ISO in 1997 .

  3. Vibrational Product States from Reactions of CN(-) with the Hydrogen Halides and Hydrogen Atoms,

    DTIC Science & Technology

    1981-01-15

    in these Several of the postulated schemes to synthesize CNH distributions. Each distribution is normalized to 1.0 ignoring in outer space are based on...been observed in interstellar space . 22-24 (3) One major advantage of studying HCN instead of, say, CO 2 is that the V3 mode of HCN is very anharmonic... Nebula by radio emission. 22,54-58 (Table IV) for the P3 modes of HCN and CNH in Reactions to- (6). The hatched areas are indications of the errors

  4. Sensing behavior of a graphene quantum dot phenalenyl towards toxic gases

    NASA Astrophysics Data System (ADS)

    Sharma, Vaishali; Narayan, Som; Dabhi, Shweta D.; Shinde, Satyam; Jha, Prafulla K.

    2018-04-01

    In the present work, by studying the interaction of graphene quantum dot (GQD) Phenalenylwith toxic gases hydrogen cyanide (HCN) and phosgene (COCl2) using density functional theory, we are aiming to evaluate the possibility of using GQD phenalenyl in the detection of HCN and COCl2. Owing to strong interactions between HCN/COCl2 and the GQD Phenalenyl, dramatic changes in the electronic properties of the graphene quantum dots together with highest occupied molecular orbitals and lowest unoccupied molecularorbitals (HOMO-LUMO) gap variationsare observed. The findings show that the GQD phenalenyl can be used as chemical nanosensor to detect HCN and COCl2 toxic gases.

  5. Structural isomers of C2N(+) - A selected-ion flow tube study

    NASA Technical Reports Server (NTRS)

    Knight, J. S.; Petrie, S. A. H.; Freeman, C. G.; Mcewan, M. J.; Mclean, A. D.

    1988-01-01

    Reactivities of the structural isomers CCN(+) and CNC(+) were examined in a selected-ion flow tube at 300 + or - 5 K. The less reactive CNC(+) isomer was identified as the product of the reactions of C(+) + HCN and C(+) + C2N2; in these reactions only CNC(+) can be produced because of energy constraints. Rate coefficients and branching ratios are reported for the reactions of each isomer with H2, CH4, NH3, H2O, C2H2, HCN, N2, O2, N2O, and CO2. Ab initio calculations are presented for CCN(+) and CNC(+); a saddle point for the reaction CCN(+) yielding CNC(+) is calculated to be 195 kJ/mol above CNC(+). The results provide evidence that the more reactive CCN(+) isomer is unlikely to be present in measurable densities in interstellar clouds.

  6. Hydrogen cyanide in the headspace of oral fluid and in mouth-exhaled breath.

    PubMed

    Chen, W; Metsälä, M; Vaittinen, O; Halonen, L

    2014-06-01

    Mouth-exhaled hydrogen cyanide (HCN) concentrations have previously been reported to originate from the oral cavity. However, a direct correlation between the HCN concentration in oral fluid and in mouth-exhaled breath has not been explicitly shown. In this study, we set up a new methodology to simultaneously measure HCN in the headspace of oral fluid and in mouth-exhaled breath. Our results show that there is a statistically significant correlation between stimulated oral fluid HCN and mouth-exhaled HCN (rs = 0.76, p < 0.001). This confirms that oral fluid is the main contributor to mouth-exhaled HCN. Furthermore, we observe that after the application of an oral disinfectant, both the stimulated oral fluid and mouth-exhaled HCN concentrations decrease. This implies that HCN production in the oral cavity is related to the bacterial and/or enzymatic activity.

  7. Far-infrared laser diagnostics on the HT-6M tokamak

    NASA Astrophysics Data System (ADS)

    Gao, X.; Lu, H. J.; Guo, Q. L.; Wan, Y. X.; Tong, X. D.

    1995-01-01

    A multichannel far-infrared (FIR) hydrogen cyanide (HCN) laser interferometer was developed to measure plasma electron density profile on the HT-6M tokamak. The structure of the seven-channel FIR laser interferometer is described. The laser source used in the interferometer was a continuous-wave glow discharge HCN laser with a cavity length of 3.4 m and power output of about 100 mW at 337 μm. The detection sensitivity was 1/15 fringe with a temporal resolution of 0.1 ms. Experimental results were measured by the seven-channel FIR HCN laser interferometer with edge Ohmic heating, a pumping limiter, and ion cyclotron resonant heating on the HT-6M tokamak are reported.

  8. Ice chemistry of acetaldehyde reveals competitive reactions in the first step of the Strecker synthesis of alanine: formation of HO-CH(CH3)-NH2 vs. HO-CH(CH3)-CN

    NASA Astrophysics Data System (ADS)

    Fresneau, Aurélien; Danger, Grégoire; Rimola, Albert; Duvernay, Fabrice; Theulé, Patrice; Chiavassa, Thierry

    2015-08-01

    The understanding of compound formation in laboratory simulated astrophysical environments is an important challenge in obtaining information on the chemistry occurring in these environments. We here investigate by means of both laboratory experiments and quantum chemical calculations the ice-based reactivity of acetaldehyde (CH3CHO) with ammonia (NH3) and hydrogen cyanide (HCN) in excess of water (H2O) promoted by temperature. A priori, this study should give information on alanine (2HN-CH(CH3)-COOH) formation (the simplest chiral amino acid detected in meteorites), since these reactions concern the first steps of its formation through the Strecker synthesis. However, infrared spectroscopy, mass spectrometry with HC14N or HC15N isotopologues and B3LYP-D3 results converge to indicate that an H2O-dominated ice containing CH3CHO, NH3 and HCN not only leads to the formation of α-aminoethanol (2HN-CH(CH3)-OH, the product compound of the first step of the Strecker mechanism) and its related polymers (2HN-(CH(CH3)-O)n-H) due to reaction between CH3CHO and NH3, but also to the 2-hydroxypropionitrile (HO­-CH(CH3)-CN) and its related polymers (H-(O-CH(CH3))n-CN) from direct reaction between CH3CHO and HCN. The ratio between these two species depends on the initial NH3/HCN ratio in the ice. Formation of α-aminoethanol is favoured when the NH3 concentration is larger than HCN. We also show that the presence of water is essential for the formation of HO­-CH(CH3)-CN, contrarily to 2HN-CH(CH3)-OH whose formation also takes place in absence of H2O ice. As in astrophysical ices NH3 is more abundant than HCN, formation of α-aminoethanol should consequently be favoured compared to 2-hydroxypropionitrile, thus pointing out α-aminoethanol as a plausible intermediate species for alanine synthesis through the Strecker mechanism in astrophysical ices.

  9. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aguado, Alfredo; Roncero, Octavio; Zanchet, Alexandre

    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 differencesmore » 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.« less

  10. Cooperative and diminutive unusual weak bonding in F3CX···HMgH···Y and F3CX···Y···HMgH trimers (X = Cl, Br; Y = HCN, and HNC).

    PubMed

    Solimannejad, Mohammad; Malekani, Masumeh; Alkorta, Ibon

    2010-11-18

    MP2 calculations with cc-pVTZ basis set were used to analyze intermolecular interactions in F(3)CX···HMgH···Y and F(3)CX···Y···HMgH triads (X = Cl, Br; Y = HCN, and HNC) which are connecting with three kinds of unusual weak interactions, namely halogen-hydride, dihydrogen, and σ-hole. To understand the properties of the systems better, the corresponding dyads are also studied. Molecular geometries, binding energies, and infrared spectra of monomers, dyads, and triads were investigated at the MP2/cc-pVTZ computational level. Particular attention is given to parameters such as cooperative energies, cooperative dipole moments, and many-body interaction energies. Those complexes with simultaneous presence of a σ-hole bond and a dihydrogen bond show cooperativity energy ranging between -1.02 and -2.31 kJ mol(-1), whereas those with a halogen-hydride bond and a dihydrogen bond are diminutive, with this energetic effect between 0.1 and 0.63 kJ mol(-1). The electronic properties of the complexes have been analyzed using the molecular electrostatic potential (MEP), the electron density shift maps, and the parameters derived from the atoms in molecules (AIM) methodology.

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

    PubMed

    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.

  12. Nutrient content of young cassava leaves and assessment of their acceptance as a green vegetable in Nigeria.

    PubMed

    Awoyinka, A F; Abegunde, V O; Adewusi, S R

    1995-01-01

    Cassava (Manihot esculenta Crantz) leaves contained a high level of crude protein (29.3-32.4% dry weight) compared to a conventional vegetable, Amaranthus (19.6%). Ash was 4.6-6.4% in cassava leaf samples but 13.1% dry weight in Amaranthus. Dietary fibre was very high in all samples (26.9-39% dry weight) while HCN-potential was low (5.1-12.6 mg/100 g dry weight). Tannin was the highest in IITA red cassava leaves (29.7 mg/g) and the lowest in Amaranthus vegetable. In vitro digestibility was very low in oven dried samples (15.6-22.7%). Blanching increased protein content (except Amaranthus) and in vitro protein digestibility but decreased ash, minerals, dietary fibre and tannin, while HCN-potential was unchanged. Grinding reduced both HCN-potential and tannin by 84 and 71% respectively while oven drying only reduced the HCN content marginally. Preference studies showed that the highest percentage of respondents (25.3%) preferred Amaranthus vegetable, followed by Celosia (17.5%), Talinum (12.4%), garden egg (11.5%), with cassava leaves as the least (0.5%). Organoleptic evaluation rated cassava leaf soup inferior to Amaranthus in terms of appearance, colour and texture but equal in terms of taste and flavour and overall acceptability.

  13. [Chemistry of alpha-aminonitriles. Aziridine-2-carbonitrile: photochemical formation from 2-aminopropenenitrile

    NASA Technical Reports Server (NTRS)

    Drenkard, S.; Ferris, J.; Eschenmoser, A.

    1990-01-01

    2-Aminopropenenitrile in solvents such as MeCN, MeOH, or H2O is photoisomerized by UV light to racemic aziridine-2-carbonitrile (rac-2); the larger part of the starting material, however, fragments to HCN and MeCN. The observed photocyclization constitutes a structural connection within an ensemble of C3H4N2 compounds considered to be potentially relevant to prebiotic chemistry.

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

    PubMed

    Eckey, Karina; Wrobel, Eva; Strutz-Seebohm, Nathalie; Pott, Lutz; Schmitt, Nicole; Seebohm, Guiscard

    2014-08-15

    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 Kv7 channels is the lipid phosphatidylinositol 4,5-bisphosphate (PIP2). PIP2 increases the macroscopic current amplitude by stabilizing the open conformation of 7.1/KCNE1 channels. However, knowledge about the exact nature of the interaction is incomplete. The aim of this study was the identification of the amino acids responsible for the interaction between Kv7.1 and PIP2. We generated 13 charge neutralizing point mutations at the intracellular membrane border and characterized them electrophysiologically in complex with KCNE1 under the influence of diC8-PIP2. Electrophysiological analysis 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. Here, we identified a subset of nine residues participating in the interaction of PIP2 and Kv7.1/KCNE1. These residues may form at least two binding pockets per subunit, leading to the stabilization of channel conformations upon PIP2 binding. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  15. 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

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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).

  18. Cyanopolyyne Chemistry in TMC-1

    NASA Astrophysics Data System (ADS)

    Winstanley, N.; Nejad, L. A. M.

    1996-03-01

    Using pseudo-time-dependent models and three different reaction networks, a detailed study of the dominant reaction pathways for the formation of cyanopolyynes and their abundances in TMC-1 is presented. The analysis of the chemical reactions show that for the formation of cyanopolyynes there are two major chemical regimes. First, early times of less than ˜104 yrs when ion-molecule reactions are dominant, the main chemical route for the formation of larger cyanopolyynes is 2GIFE1.gif" Format="GIF" Color="BlackWhite" Type="Linedraw" Rendition="HTML"/> C_n H^ + xrightarrow{N}C_n N^ + xrightarrow{{H_2 }}HC_n N^ + xrightarrow{{H_2 }}H_2 C_n N^ + xrightarrow{{e^ - }}HC_n N wheren=5, 7, and 9. Second, at times greater than 104 yrs, when neutral-neutral reactions become dominant, two major reaction routes for the formation of cyanopolyynes are (a), 2GIFE2.gif" Format="GIF" Color="BlackWhite" Type="Linedraw" Rendition="HTML"/> HCNxrightarrow{{C_2 H}}HC_3 Nxrightarrow{{C_2 H}}HC_5 Nxrightarrow{{C_2 H}}HC_7 Nxrightarrow{{C_2 H}}HC_9 N and (b) 2GIFE3.gif" Format="GIF" Color="BlackWhite" Type="Linedraw" Rendition="HTML"/> C_n H_2 + CN to HC_{n + 1} N + H,{text{ }}n = 4,6, and 8 depending on the reaction network used. The results indicate that for route (a) large abundances ofC 2 H (fractional abundances of ˜10-7), and for route (b) large abundances ofC 2 H 2 are required in order to reproduce the observed abundances of cyanopolyynes. The calculated abundances of cyanopolyynes show great sensitivity to the value of extinction particularly att≳5×105 yrs (i.e. photochemical timescale). The effect of other physical parameters, such as the cosmic-ray ionization abundances are also examined. In general, the model calculations show

  19. Identification of methylated genes in salivary gland adenoid cystic carcinoma xenografts using global demethylation and methylation microarray screening

    PubMed Central

    LING, SHIZHANG; RETTIG, ELENI M.; TAN, MARIETTA; CHANG, XIAOFEI; WANG, ZHIMING; BRAIT, MARIANA; BISHOP, JUSTIN A.; FERTIG, ELANA J.; CONSIDINE, MICHAEL; WICK, MICHAEL J.; HA, PATRICK K.

    2016-01-01

    Salivary gland adenoid cystic carcinoma (ACC) is a rare head and neck malignancy without molecular biomarkers that can be used to predict the chemotherapeutic response or prognosis of ACC. The regulation of gene expression of oncogenes and tumor suppressor genes (TSGs) through DNA promoter methylation may play a role in the carcinogenesis of ACC. To identify differentially methylated genes in ACC, a global demethylating agent, 5-aza-2′-deoxycytidine (5-AZA) was utilized to unmask putative TSG silencing in ACC xenograft models in mice. Fresh xenografts were passaged, implanted in triplicate in mice that were treated with 5-AZA daily for 28 days. These xenografts were then evaluated for genome-wide DNA methylation patterns using the Illumina Infinium HumanMethylation27 BeadChip array. Validation of the 32 candidate genes was performed by bisulfite sequencing (BS-seq) in a separate cohort of 6 ACC primary tumors and 6 normal control salivary gland tissues. Hypermethylation was identified in the HCN2 gene promoter in all 6 control tissues, but hypomethylation was found in all 6 ACC tumor tissues. Quantitative validation of HCN2 promoter methylation level in the region detected by BS-seq was performed in a larger cohort of primary tumors (n=32) confirming significant HCN2 hypomethylation in ACCs compared with normal samples (n=10; P=0.04). HCN2 immunohistochemical staining was performed on an ACC tissue microarray. HCN2 staining intensity and H-score, but not percentage of the positively stained cells, were significantly stronger in normal tissues than those of ACC tissues. With our novel screening and sequencing methods, we identified several gene candidates that were methylated. The most significant of these genes, HCN2, was actually hypomethylated in tumors. However, promoter methylation status does not appear to be a major determinant of HCN2 expression in normal and ACC tissues. HCN2 hypomethylation is a biomarker of ACC and may play an important role in the

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

    PubMed

    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.

  1. Neuronal entry and high neurotoxicity of botulinum neurotoxin A require its N-terminal binding sub-domain

    PubMed Central

    Wang, Jiafu; Meng, Jianghui; Nugent, Marc; Tang, Minhong; Dolly, J. Oliver

    2017-01-01

    Botulinum neurotoxins (BoNTs) are the most toxic proteins known, due to inhibiting the neuronal release of acetylcholine and causing flaccid paralysis. Most BoNT serotypes target neurons by binding to synaptic vesicle proteins and gangliosides via a C-terminal binding sub-domain (HCC). However, the role of their conserved N-terminal sub-domain (HCN) has not been established. Herein, we created a mutant form of recombinant BoNT/A lacking HCN (rAΔHCN) and showed that the lethality of this mutant is reduced 3.3 × 104-fold compared to wild-type BoNT/A. Accordingly, low concentrations of rAΔHCN failed to bind either synaptic vesicle protein 2C or neurons, unlike the high-affinity neuronal binding obtained with 125I-BoNT/A (Kd = 0.46 nM). At a higher concentration, rAΔHCN did bind to cultured sensory neurons and cluster on the surface, even after 24 h exposure. In contrast, BoNT/A became internalised and its light chain appeared associated with the plasmalemma, and partially co-localised with vesicle-associated membrane protein 2 in some vesicular compartments. We further found that a point mutation (W985L) within HCN reduced the toxicity over 10-fold, while this mutant maintained the same level of binding to neurons as wild type BoNT/A, suggesting that HCN makes additional contributions to productive internalization/translocation steps beyond binding to neurons. PMID:28295026

  2. PECULIAR NEAR-NUCLEUS OUTGASSING OF COMET 17P/HOLMES DURING ITS 2007 OUTBURST

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Qi, Chunhua; Gurwell, Mark A.; Wilner, David J.

    2015-01-20

    We present high angular resolution Submillimeter Array observations of the outbursting Jupiter family comet 17P/Holmes on 2007 October 26-29, achieving a spatial resolution of 2.''5, or ∼3000 km at the comet distance. The observations resulted in detections of the rotational lines CO 3-2, HCN 4-3, H{sup 13}CN 4-3, CS 7-6, H{sub 2}CO 3{sub 1,} {sub 2}-2{sub 1,} {sub 1}, H{sub 2}S 2{sub 2,} {sub 0}-2{sub 1,} {sub 1}, and multiple CH{sub 3}OH lines, along with the associated dust continuum at 221 and 349 GHz. The continuum has a spectral index of 2.7 ± 0.3, slightly steeper than blackbody emission from large dust particles.more » From the imaging data, we identify two components in the molecular emission. One component is characterized by a relatively broad line width (∼1 km s{sup –1} FWHM) exhibiting a symmetric outgassing pattern with respect to the nucleus position. The second component has a narrower line width (<0.5 km s{sup –1} FWHM) with the line center redshifted by 0.1-0.2 km s{sup –1} (cometocentric frame), and shows a velocity shift across the nucleus position with the position angle gradually changing from 66° to 30° within the four days of observations. We determine distinctly different CO/HCN ratios for each of the components. For the broad-line component we find CO/HCN < 7, while in the narrow-line component, CO/HCN = 40 ± 5. We hypothesize that the narrow-line component originates from the ice grain halo found in near-nucleus photometry, believed to be created by sublimating recently released ice grains around the nucleus during the outburst. In this interpretation, the high CO/HCN ratio of this component reflects the more pristine volatile composition of nucleus material released in the outburst.« less

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Myristoylated peptides potentiate the funny current (If) in sinoatrial myocytes

    PubMed Central

    Liao, Zhandi; St Clair, Joshua R; Larson, Eric D

    2011-01-01

    The funny current, If, in sinoatrial myocytes is thought to contribute to the sympathetic fight-or-flight increase in heart rate. If is produced by hyperpolarization-activated cyclic nucleotide sensitive-4 (HCN4) channels, and it is widely believed that sympathetic regulation of If occurs via direct binding of cAMP to HCN4, independent of phosphorylation. However, we have recently shown that Protein Kinase A (PKA) activity is required for sympathetic regulation of If, and that PKA can directly phosphorylate HCN4.1 In the present study, we examined the effects of a myristoylated PKA inhibitory peptide (myr-PKI) on If in mouse sinoatrial myocytes. We found that myr-PKI and another myristoylated peptide potently and specifically potentiated If via a mechanism that did not involve PKA inhibition and that was independent of the peptide sequence, Protein Kinase C or phosphatidylinositol-4,5-bisphosphate. The off-target activation of If by myristoylated peptides limits their usefulness for studies of pacemaker mechanisms in sinoatrial myocytes. PMID:21150293

  7. Hyperpolarization-activated cation channels in fast-spiking interneurons of rat hippocampus

    PubMed Central

    Aponte, Yexica; Lien, Cheng-Chang; Reisinger, Ellen; Jonas, Peter

    2006-01-01

    Hyperpolarization-activated channels (Ih or HCN channels) are widely expressed in principal neurons in the central nervous system. However, Ih in inhibitory GABAergic interneurons is less well characterized. We examined the functional properties of Ih in fast-spiking basket cells (BCs) of the dentate gyrus, using hippocampal slices from 17- to 21-day-old rats. Bath application of the Ih channel blocker ZD 7288 at a concentration of 30 μm induced a hyperpolarization of 5.7 ± 1.5 mV, an increase in input resistance and a correlated increase in apparent membrane time constant. ZD 7288 blocked a hyperpolarization-activated current in a concentration-dependent manner (IC50, 1.4 μm). The effects of ZD 7288 were mimicked by external Cs+. The reversal potential of Ih was −27.4 mV, corresponding to a Na+ to K+ permeability ratio (PNa/PK) of 0.36. The midpoint potential of the activation curve of Ih was −83.9 mV, and the activation time constant at −120 mV was 190 ms. Single-cell expression analysis using reverse transcription followed by quantitative polymerase chain reaction revealed that BCs coexpress HCN1 and HCN2 subunit mRNA, suggesting the formation of heteromeric HCN1/2 channels. ZD 7288 increased the current threshold for evoking antidromic action potentials by extracellular stimulation, consistent with the expression of Ih in BC axons. Finally, ZD 7288 decreased the frequency of miniature inhibitory postsynaptic currents (mIPSCs) in hippocampal granule cells, the main target cells of BCs, to 70 ± 4% of the control value. In contrast, the amplitude of mIPSCs was unchanged, consistent with the presence of Ih in inhibitory terminals. In conclusion, our results suggest that Ih channels are expressed in the somatodendritic region, axon and presynaptic elements of fast-spiking BCs in the hippocampus. PMID:16690716

  8. Meta-path based heterogeneous combat network link prediction

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    PubMed

    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.

  11. Effect of Fluorocarbon and Hydrocarbon Chain Lengths in Hybrid Surfactants for Supercritical CO2.

    PubMed

    Sagisaka, Masanobu; Ono, Shinji; James, Craig; Yoshizawa, Atsushi; Mohamed, Azmi; Guittard, Frédéric; Rogers, Sarah E; Heenan, Richard K; Yan, Ci; Eastoe, Julian

    2015-07-14

    Hybrid surfactants containing both fluorocarbon (FC) and hydrocarbon (HC) chains have recently been shown to solubilize water and form elongated reversed micelles in supercritical CO2. To clarify the most effective FC and HC chain lengths, the aggregation behavior and interfacial properties of hybrid surfactants FCm-HCn (FC length m/HC length n = 4/2, 4/4, 6/2, 6/4, 6/5, 6/6, and 6/8) were examined in W/CO2 mixtures as functions of pressure, temperature, and water-to-surfactant molar ratio (W0). The solubilizing power of hybrid surfactants for W/CO2 microemulsions was strongly affected by not only the FC length but also by that of the HC. Although the surfactants having short FC and/or HC tails (namely, m/n = 4/2, 4/4, and 6/2) did not dissolve in supercritical CO2 (even at ∼17 mM, ≤400 bar, temperature ≤ 75 °C, and W0 = 0-40), the other hybrid surfactants were able to yield transparent single-phase W/CO2 mixtures identified as microemulsions. The solubilizing power of FC6-HCm surfactants reached a maximum (W0 ∼ 80 at 45 °C and 350 bar) with a hydrocarbon length, m, of 4. The W0 value of 80 is the highest for a HC-FC hybrid surfactant, matching the highest value reported for a FC surfactant which contained more FC groups. High-pressure small-angle neutron scattering measurements from FCm-HCn/D2O/CO2 microemulsions were consistent with growth of the microemulsion droplets with increasing W0. In addition, not only spherical reversed micelles but also nonspherical assemblies (rodlike or ellipsoidal) were found for the systems with FC6-HCn (n = 4-6). At fixed surfactant concentration and W0 (17 mM and W0 = 20), the longest reversed micelles were obtained for FC6-HC6 where a mean aspect ratio of 6.3 was calculated for the aqueous cores.

  12. Isotopic Ratios in Nitrile Species on Titan using ALMA

    NASA Astrophysics Data System (ADS)

    Molter, Edward; Nixon, Conor; Cordiner, Martin; Serigano, Joseph; Irwin, Patrick; Teanby, Nicholas; Charnley, Steven; Lindeberg, Johan

    2016-06-01

    The atmosphere of Titan is primarily composed of molecular nitrogen (N2, ˜98%) and methane (CH4, ˜2%), but also hosts a myriad of trace organic species. Two of the simplest and most abundant of these are hydrogen cyanide (HCN) and cyanoacetylene (HC3N). The advent of ALMA provides the opportunity to observe rotational transitions in these molecules and their isotopologues with unprecendented sensitivity and spatial resolution. We searched through the ALMA archive for publicly available high-resolution observations of Titan as a flux calibrator source taken between April and July 2014; each integration lasted around 160 seconds. Using spectra of HCN and HC3N isotopologues found in these data, we derive vertical abundance profiles and determine the isotopic ratios 14N/15N and 12C/13C in these molecules. We also report the detection of a new HCN isotopologue on Titan, H13C6 15N, and use a high signal-to-noise spectrum of DCN to determine the D/H ratio in HCN on Titan for the first time. These isotopic ratios are leveraged to constrain the physical and chemical processes occurring in Titan's atmosphere.

  13. Organic Molecules in Oxygen-Rich Circumstellar Envelopes: Methanol and Hydrocarbons

    NASA Technical Reports Server (NTRS)

    Charnley, S. B.; Tielens, A. G. G. M.; Kress, M. E.

    1995-01-01

    The existence of anomalously high abundances of gaseous CH4 has been invoked to explain the unexpectedly high abundances of the carbon-bearing molecules HCN and H2CO in the outflows from O-rich red giants. We have modelled the chemistry that proceeds in the outer envelope when CH4 is injected from the inner envelope. We find that photolysis by the interstellar radiation field drives an ion-neutral chemistry which produces several organic molecules. The calculated abundances of CH3OH, C2H and C2 can be comparable to those calculated for H2CO and HCN. Species such as C2H4, C2H2 and CH3CN can also be abundant. A search for CH3OH and C2H in several O-rich outflows known to exhibit strong HCN emission is needed. As it derives entirely from the CH4 photochain, is insensitive to the envelope temperature distribution, and has accessible transitions at millimetre wavelengths, the detection of the C2H radical would provide further indirect support for the presence of the hypothesized methane.

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

    PubMed

    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.

  15. Atmospheric Pseudohalogen Chemistry

    NASA Technical Reports Server (NTRS)

    Lary, David John

    2004-01-01

    Hydrogen cyanide is not usually considered in atmospheric chemical models. The paper presents three reasons why hydrogen cyanide is likely to be significant for atmospheric chemistry. Firstly, HCN is a product and marker of biomass burning. Secondly, it is also likely that lightning is producing HCN, and as HCN is sparingly soluble it could be a useful long-lived "smoking gun" marker of lightning activity. Thirdly, the chemical decomposition of HCN leads to the production of small amounts of the cyanide (CN) and NCO radicals. The NCO radical can be photolyzed in the visible portion of the spectrum yielding nitrogen atoms (N). The production of nitrogen atoms is significant as it leads to the titration of total nitrogen from the atmosphere via N+N->N2, where N2 is molecular nitrogen.

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

    NASA Astrophysics Data System (ADS)

    Chung, Dongwoo T.; Li, Tony Y.; Viero, Marco P.; Church, Sarah E.; Wechsler, Risa H.

    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%.

  17. Updated population metadata for United States historical climatology network stations

    USGS Publications Warehouse

    Owen, T.W.; Gallo, K.P.

    2000-01-01

    The United States Historical Climatology Network (HCN) serial temperature dataset is comprised of 1221 high-quality, long-term climate observing stations. The HCN dataset is available in several versions, one of which includes population-based temperature modifications to adjust urban temperatures for the "heat-island" effect. Unfortunately, the decennial population metadata file is not complete as missing values are present for 17.6% of the 12 210 population values associated with the 1221 individual stations during the 1900-90 interval. Retrospective grid-based populations. Within a fixed distance of an HCN station, were estimated through the use of a gridded population density dataset and historically available U.S. Census county data. The grid-based populations for the HCN stations provide values derived from a consistent methodology compared to the current HCN populations that can vary as definitions of the area associated with a city change over time. The use of grid-based populations may minimally be appropriate to augment populations for HCN climate stations that lack any population data, and are recommended when consistent and complete population data are required. The recommended urban temperature adjustments based on the HCN and grid-based methods of estimating station population can be significantly different for individual stations within the HCN dataset.

  18. Measurements of Gas and Particle Phase Emissions From Munitions Detonation in a Field Environment

    NASA Astrophysics Data System (ADS)

    Fortner, E. C.; Knighton, W. B.; Timko, M.; Wood, E.; Onasch, T. B.; Kolb, C. E.; Beardsley, H. M.

    2007-12-01

    During the Point of Fire (POF) field campaign conducted at Fort Sill Oklahoma U.S.A. in March 2007 a suite of real- time trace gas and fine (submicron) particulate matter (PM) instrumentation characterized the point of fire emission plumes from large, medium and small caliber weapons systems. Muzzle emission plumes were measured and where appropriate, breach plumes and gun crew breathing zone measurements were also conducted. Aerosol measurements were conducted with an aerosol mass spectrometer (Aerodyne CTOF-AMS) for particle composition, condensation particle counter (CPC) for particle number density and DUSTRAK aerosol monitor for particle mass. Gas phase measurements included CO, CO2, NOx and a variety of trace gas species measured by proton transfer reaction mass spectrometry (PTR-MS) including hydrogen cyanide (HCN), acetonitrile, acrylonitrile, benzene, toluene, benzonitrile and styrene. In the majority of the plume measurements, HCN was the most prominent compound measured by PTR-MS. Quantification of HCN by PTR-MS is difficult due to its proton affinity being close enough to that of water to allow a significant backward reaction of protonated HCN with water, reducing the detection sensitivity and making the response dependent on humidity. We have developed a quantification procedure for HCN based on laboratory measurements of a calibration gas standard of HCN, which allows the humidity dependence to be extracted directly from the proton hydrate ion intensities. The correction factors for HCN are quite significant varying between 10 and 30 depending on sample humidity.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Edwards, J. L.; Ziurys, L. M., E-mail: lziurys@email.arizona.edu

    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 multiplemore » 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 ☉}.« less

  20. OH megamasers: dense gas & the infrared radiation field

    NASA Astrophysics Data System (ADS)

    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}<10L_{⊙}, OH kMs), OH absorbers and OH non-detections (non-OH MM). Through comparative analysis on their infrared emission, CO and HCN luminosities (good tracers for the low-density 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.

  1. Ground-based infrared spectroscopic measurements of atmospheric hydrogen cyanide

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Smith, M. A. H.; Rinsland, P. L.; Goldman, A.; Brault, J. W.; Stokes, G. M.

    1982-01-01

    A number of lines of the nu-3 band of hydrogen cyanide have been detected in solar absorption spectra recorded near sunrise and sunset at Kitt Peak National Observatory (elevation 2095 m) with a 0.01/cm resolution Fourier transform spectrometer. Analysis of two of the strongest and best isolated lines has led to a value of 2.73 x 10 to the 15th molecules/sq cm for the vertical column abundance of HCN above Kitt Peak. The accuracy of this value is estimated as + or - 25%. This result, combined with the stratospheric concentration of HCN derived by Coffey, Mankin, and Cicerone (1981), yields 166 parts per trillion by volume for the average mixing ratio of HCN between 2 and 12 km. This is the first determination of the HCN concentration in the nonurban troposphere.

  2. Hyperswitch communication network

    NASA Technical Reports Server (NTRS)

    Peterson, J.; Pniel, M.; Upchurch, E.

    1991-01-01

    The Hyperswitch Communication Network (HCN) is a large scale parallel computer prototype being developed at JPL. Commercial versions of the HCN computer are planned. The HCN computer being designed is a message passing multiple instruction multiple data (MIMD) computer, and offers many advantages in price-performance ratio, reliability and availability, and manufacturing over traditional uniprocessors and bus based multiprocessors. The design of the HCN operating system is a uniquely flexible environment that combines both parallel processing and distributed processing. This programming paradigm can achieve a balance among the following competing factors: performance in processing and communications, user friendliness, and fault tolerance. The prototype is being designed to accommodate a maximum of 64 state of the art microprocessors. The HCN is classified as a distributed supercomputer. The HCN system is described, and the performance/cost analysis and other competing factors within the system design are reviewed.

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

    NASA Technical Reports Server (NTRS)

    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

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

    PubMed

    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.

  5. Nitrogen chemistry during burnout in fuel-staged combustion

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kristensen, P.G.; Glarborg, P.; Dam-Johansen, K.

    A parametric study of the chemistry of the burnout zone in reburning has been performed in laboratory plug flow reactors in the temperature range 800--1,350 K. Inlet mole fractions of NO, NH{sub 3}, HCN, CO, and O{sub 2} were varied, together with different temperatures and residence times to simulate reaction conditions in practical systems. Under lean conditions, a minimum in NO emission exists as a function of temperature. Both HCN and NH{sub 3} can act as either NO reductants or as sources for NO by oxidation. Reactions and selectivities for HCN and NH{sub 3} are controlled by the radical poolmore » produced by fuel (CO) oxidation. As increasing amounts of CO were added, temperatures for both ignition and the minimum in NO became lower. At 2% CO, 4% O{sub 2}, and 100 ms residence time, the minimum in NO was found at approximately 1,000 K. At low temperatures, significant amounts of N{sub 2}O were measured in the reactor outlet. This is attributed to N{sub 2}O formation by HCN/NO reactions and to the slow decomposition of N{sub 2}O at these temperatures. Large reductions in NO were seen under fuel-rich conditions and at high temperatures. The observed NO reduction was very much dependent on the inlet mole fraction of O{sub 2}. Detailed chemical kinetic modeling of the experiments showed reasonable predictions for overall fuel-lean conditions, but the model failed to predict experimental results under fuel-rich conditions. The present results provide guidelines for optimizing the conditions for the burnout process of reburning, as well as other processes for NO{sub x} reduction by staged combustion. The results also provide a test basis for verifying kinetic models for nitrogen chemistry at low temperatures (800--1,350 K).« less

  6. Vinken and Bruyn's Handbook of Clinical Neurology. A witness of late-twentieth century neurological progress.

    PubMed

    Koehler, P J; Jennekens, F G I

    2008-01-01

    Vinken and Bruyn's Handbook of Clinical Neurology (HCN) is best characterized as an encyclopedia. In this paper we describe the origin, production, and reception of HCN. Data were gathered from a literature search, by screening of HCN-volumes, interviewing key-role persons and a study of an HCN-archive. The initiative for HCN was taken by two Excerpta Medica staff members, the one a strategist with expertise in information systems, the other a gifted neurologist with an expert knowledge of who is who in the world of neurological literature. Within a period of 38 years, 2799 authors, 28 volume editors, the two initiators, and a third chief editor for the American continent described the whole of neurology in 1909 chapters on all together 46,025 pages (excluding index volumes). HCN was sold mainly to medical institutes in affluent countries. A digital version of the revised edition was proposed by the editors but refused by the publisher for commercial reasons. HCN was in general well received by book reviewers. The main criticisms concerned the price of the volumes, lack of editorial control, inadequacy of indexes, and lack of cross references. HCN offers unrivalled information on the state of the art of the clinical neurosciences in the second half of the twentieth century. In addition, it contains extensive reviews of the history of neurological diseases in the volumes of the original edition.

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

    PubMed Central

    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

  8. Optical depth estimates and effective critical densities of dense gas tracers in the inner parts of nearby galaxy discs

    NASA Astrophysics Data System (ADS)

    Jiménez-Donaire, M. J.; Bigiel, F.; Leroy, A. K.; Cormier, D.; Gallagher, M.; Usero, A.; Bolatto, A.; Colombo, D.; García-Burillo, S.; Hughes, A.; Kramer, C.; Krumholz, M. R.; Meier, D. S.; Murphy, E.; Pety, J.; Rosolowsky, E.; Schinnerer, E.; Schruba, A.; Tomičić, N.; Zschaechner, L.

    2017-04-01

    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 thin isotopologues H13CN, H13CO+ and HN13C (1-0) to measure isotopologue line ratios. We use IRAM 30-m observations from the large programme EMPIRE and new Atacama Large Millimetre/submillimetre Array observations, which together target six nearby star-forming galaxies. Using spectral stacking techniques, we calculate or place strong upper limits on the HCN/H13CN, HCO+/H13CO+ and HNC/HN13C line ratios in the inner parts of these galaxies. Under simple assumptions, we use these to estimate the optical depths of HCN (1-0) and HCO+ (1-0) to be τ ˜ 2-11 in the active, inner regions of our targets. The critical densities are consequently lowered to values between 5 and 20 × 105 cm-3, 1 and 3 × 105 cm-3 and 9 × 104 cm-3 for HCN, HCO+ and HNC, respectively. We study the impact of having different beam-filling factors, η, on these estimates and find that the effective critical densities decrease by a factor of η _{12}/η _{13} τ_{12}. A comparison to existing work in NGC 5194 and NGC 253 shows the HCN/H13CN and HCO+/H13CO+ ratios in agreement with our measurements within the uncertainties. The same is true for studies in other environments such as the Galactic Centre or nuclear regions of active galactic nucleus dominated nearby galaxies.

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

    NASA Technical Reports Server (NTRS)

    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.

  10. Trace gas emissions from combustion of peat, crop residue, domestic biofuels, grasses, and other fuels: configuration and Fourier transform infrared (FTIR) component of the fourth Fire Lab at Missoula Experiment (FLAME-4)

    NASA Astrophysics Data System (ADS)

    Stockwell, C. E.; Yokelson, R. J.; Kreidenweis, S. M.; Robinson, A. L.; DeMott, P. J.; Sullivan, R. C.; Reardon, J.; Ryan, K. C.; Griffith, D. W. T.; Stevens, L.

    2014-09-01

    . Burning alfalfa produced the highest average NH3 EF observed in the study (6.63 ± 2.47 g kg-1), while sugar cane fires produced the highest EF for glycolaldehyde (6.92 g kg-1) and other reactive oxygenated organic gases such as HCHO, HCOOH, and CH3COOH. Due to the high sulfur and nitrogen content of tires, they produced the highest average SO2 emissions (26.2 ± 2.2 g kg-1) and high NOx and HONO emissions. High variability was observed for peat fire emissions, but they were consistently characterized by large EFs for NH3 (1.82 ± 0.60 g kg-1) and CH4 (10.8 ± 5.6 g kg-1). The variability observed in peat fire emissions, the fact that only one peat fire had previously been subject to detailed emissions characterization, and the abundant emissions from tropical peatlands all impart high value to our detailed measurements of the emissions from burning three Indonesian peat samples. This study also provides the first EFs for HONO and NO2 for Indonesian peat fires. Open cooking fire emissions of HONO and HCN are reported for the first time, and the first emissions data for HCN, NO, NO2, HONO, glycolaldehyde, furan, and SO2 are reported for "rocket" stoves: a common type of improved cookstove. The HCN / CO emission ratios for cooking fires (1.72 × 10-3 ± 4.08 × 10-4) and peat fires (1.45 × 10-2 ± 5.47 × 10-3) are well below and above the typical values for other types of biomass burning, respectively. This would affect the use of HCN / CO observations for source apportionment in some regions. Biomass burning EFs for HCl are rare and are reported for the first time for burning African savanna grasses. High emissions of HCl were also produced by burning many crop residues and two grasses from coastal ecosystems. HCl could be the main chlorine-containing gas in very fresh smoke, but rapid partitioning to aerosol followed by slower outgassing probably occurs.

  11. Nitrogen isotopic fractionation during plasma synthesis of Titan's aerosols analogues

    NASA Astrophysics Data System (ADS)

    Kuga, M.; Carrasco, N.; Marty, B.; Marrocchi, Y.; Bernard, S.; Rigaudier, T.

    2013-12-01

    The Cassini-Huygens mission recently provided measurements of the abundance of nitrogen isotopes in Titan's atmosphere. The 14N/15N ratio in the two most abundant N-bearing molecules in Titan's atmosphere was found to be 183×5 for N2 [1] and 56×8 for HCN [2]. Those two molecules are greatly enriched in the heavier isotope 15N compared to our terrestrial atmosphere and Titan's HCN is about three times richer in 15N than its potential photochemical precursor N2. This implies an important fractionation process in the HCN production chain, which is tentatively attributed to an isotopic selectivity of the photodissociation of N2 in Titan's ionosphere [3-4]. The organic aerosols, forming the Titan's orange characteristic haze layers, also contain large amounts of nitrogen [5], and thus represent a third important nitrogen reservoir in Titan's atmosphere. These organic aerosols are presumably produced in the upper atmosphere by chemical reactions between N2 and CH4 induced by solar radiation and electron bombardment from Saturn's magnetosphere. As HCN is a possible precursor for aerosol polymerization [6-7], the 15N enrichment observed in HCN may be linked to the polymerization process. Unfortunately, no data exists on the isotopic nitrogen abundance in Titan's aerosols, and this question remains open. To address this issue, laboratory aerosols analogues have been produced in a N2-CH4 plasma and their nitrogen isotopic composition have been investigated. In this study, the experimental aerosols, called " tholins ", have been synthetized in the PAMPRE reactor (LATMOS, France). This setup is dedicated to simulate chemical processes occurring in Titan's atmosphere and consists in an RF plasma discharge initiated in a N2-CH4 gas mixture at room temperature [8-9]. For our purpose, tholins were produced at different initial CH4 percentages (1, 2, 5, 10%), representative of the variation of the CH4 concentration in Titan's atmosphere. 15N/14N ratio of the N2 gas used in the

  12. A mass cyanide poisoning from pickling bamboo shoots.

    PubMed

    Sang-A-Gad, Pensiriwan; Guharat, Suriya; Wananukul, Winai

    2011-11-01

    Bamboo shoots contain cyanogenic glycosides named taxiphyllin. Cyanide poisoning from cyanogenic glycosides commonly occurs following ingestion. However, toxicity caused by inhalation of hydrogen cyanide gas (HCN) produced from pickled shoots has never been reported. To describe cyanide poisoning in eight victims who were exposed to HCN produced in a well containing pickling bamboo shoots. Due to a series of botched rescue attempts, a total of eight patients entered into a 27 m(3) well containing pickled bamboo shoots and immediately lost consciousness. After rescue, two patients developed cardiac arrest, metabolic acidosis and died. Four other patients suffered metabolic acidosis, but recovered after supportive care. The remaining two regained consciousness and recovered soon after the event. Ambient air study and cyanide content of bamboo shoots helped confirm the diagnosis. All patients had high anion gap metabolic acidosis with normal oxygenation. Blood cyanide levels ranged from 2.66 to 3.30 mcg/ml (taken after about 18 h of incident). Ambient air study (21 h after incident) revealed oxygen 20.9%, and sulfur dioxide 19.4 ppm. The instrument was unfortunately not equipped to detect HCN. A simulation study revealed HCN and sulfur dioxide in the ambient air at 10 ppm and 7.5 ppm, respectively. Cyanide content in the bamboo shoots ranged from 39 to 434 mg/kg in the wet shoots. This series of patients developed sudden onset of alteration of consciousness and metabolic acidosis upon exposure, and cyanide was confirmed in all victims. The simulation study confirmed the presence of HCN in the ambient air of the well containing bamboo shoots. We have reported mass acute cyanide poisoning with two fatalities. The source of HCN was unusual as it was produced from pickling bamboo shoot.

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

    PubMed Central

    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

  14. Trace Gas Measurements in Nascent, Aged and Cloud-processed Smoke from Africa Savanna Fires by Airborne Fourier Transform Infrared Spectroscopy (AFTIR)

    NASA Technical Reports Server (NTRS)

    Yokelson, Robert J.; Bertschi, Isaac T.; Christian, Ted J.; Hobbs, Peter V.; Ward, Darold E.; Hao, Wei Min

    2003-01-01

    We measured stable and reactive trace gases with an airborne Fourier transform infrared spectrometer (AFTIR) on the University of Washington Convair-580 research aircraft in August/September 2000 during the SAFARI 2000 dry season campaign in Southern Africa. The measurements included vertical profiles of C02, CO, H20, and CH4 up to 5.5 km on six occasions above instrumented ground sites and below the TERRA satellite and ER-2 high-flying research aircraft. We also measured the trace gas emissions from 10 African savanna fires. Five of these fires featured extensive ground-based fuel characterization, and two were in the humid savanna ecosystem that accounts for most African biomass burning. The major constituents we detected in nascent CH3OOH, HCHO, CH30H, HCN, NH3, HCOOH, and C2H2. These are the first quantitative measurements of the initial emissions of oxygenated volatile organic compounds (OVOC), NH3, and HCN from African savanna fires. On average, we measured 5.3 g/kg of OVOC and 3.6 g/kg of hydrocarbons (including CH4) in the initial emissions from the fires. Thus, the OVOC will have profound, largely unexplored effects on tropical tropospheric chemistry. The HCN emission factor was only weakly dependent on fire type; the average value (0.53 g/kg) is about 20 times that of a previous recommendation. HCN may be useful as a tracer for savanna fires. Delta O3/Delta CO and Delta CH3COO/Delta CO increased to as much as 9% in <1 h of photochemical processing downwind of fires. Direct measurements showed that cloud processing of smoke greatly reduced CH30H, NH3, CH3COOH, SO2, and NO2 levels, but significantly increased HCHO and NO.

  15. Radio line observations of comet 109P/Swift-Tuttle at IRAM

    NASA Astrophysics Data System (ADS)

    Despois, D.; Biver, N.; Bockelée-Morvan, D.; Colom, P.; Crovisier, J.; Paubert, G.

    1996-06-01

    Observations are presented of comet 109P/Swift-Tuttle (1992t and 1992 XXVIII in the old style designations) obtained at the IRAM 30 m millimetre radio telescope both before (Nov. 1992) and after perihelion (Jan. 1993), when rh was ˜ 1 AU and Δ between 1 and 2 AU. The molecules HCN, H 2S, H 2CO and CH 2OH were detected, with good signal-to-noise ratios (up to 30). The line profiles are strongly asymmetric with a cusp at negative velocities; this leads to an important shift (-0.45 km s -1) of the mean gas velocity with respect to the nucleus. This profile is most probably linked to the jets seen at visual wavelengths. From methanol rotation diagrams, average rotational temperatures of 70 K for November 21 and 45 K for January are estimated. An isotropic distribution of the molecules is assumed, and Q(H 2O) ˜ 4.0 and 3.5 × 10 29 molec. s -1 for November 21 and January, respectively. Relative production rates Q/Q (H 2O) of 0.1, 0.4, 0.5 and 4-7% on November 21, 1992 for HCN, H 2S, H 2CO and CH 3OH, respectively, and 0.05, 0.2 and 2% on January 6-7, 1993, for HCN, H 2CO and CH 3OH, respectively, are derived. The effect of coma anisotropy on the derivation of these rates is briefly discussed. The decrease of non-water parent molecules from November to January, to be confirmed, raises questions about the nucleus homogeneity or sublimation process.

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

    NASA Technical Reports Server (NTRS)

    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.

  17. Photosynthesis of organic compounds in the atmosphere of Jupiter

    NASA Technical Reports Server (NTRS)

    Ferris, J. P.; Chen, C. T.

    1975-01-01

    An efficient conversion of CH4 to hydrocarbons and HCN takes place when NH3 is photolysed in the presence of CH4, H2, and He using a 184.9 nm light source. The extent of NH3 decomposition after a 1 hr exposure was determined spectrophotometrically; CH4, N2, and C2 and C3 hydrocarbons were detected and analyzed by mass spectrometry. Photolysis of one molar equivalent of NH3 results in the loss of 0.84 molar equivalent of CH4, which apparently reacts with hot hydrogen atoms produced by photolysis. The 8% of the NH3 which is not converted to N2 probably is converted to organic amines and nitrile derivatives. The results indicate that NH3 photolysis is a highly probable mechanism for the conversion of methane to more complex hydrocarbons in the upper atmosphere of Jupiter, and predict the occurrence of HCN, NH2NH2, and higher hydrocarbons in the Jovian atmosphere above the NH3 clouds.

  18. Cyanogenic Pseudomonas spp. strains are concentrated in the rhizosphere of alpine pioneer plants.

    PubMed

    Rijavec, Tomaž; Lapanje, Aleš

    2017-01-01

    HCN producing bacteria have previously been isolated from alpine mineral soil and their ecophysiology was presumed to be associated with mineral weathering. Nevertheless, the high ecological patchiness of the alpine environment calls for an extensive and detailed analysis of the spatial distribution of HCN producing bacterial populations and their associated weathering traits. Our results of such an analysis showed that primarily the rhizosphere of pioneer plants was rich in HPPs, harbouring the most potent HCN producers. HCN production incidence and intensity were dependent on the plant-associated microhabitat and type of bedrock/mineral soil, however the HCN+ phenotype was not associated with one of the particular genotypes which we determined by BOX-PCR. In HPP isolates, HCN production most commonly co-occurred with the production of hydroxamate-type siderophores, but was less often associated with inorganic phosphate solubilization activity and the production of catechol-type siderophores. These observations indicate that a plant's physiotype, not species, provide physicochemical conditions that determine selective pressure, which enables the growth of Pseudomonas spp. with a random genotype, but phenotypically predetermined to increase mineral weathering via a particular combination of phosphate solubilization and iron complexation with siderophores and HCN. Copyright © 2016 Elsevier GmbH. All rights reserved.

  19. Non-LTE models of Titan's upper atmosphere

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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

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

    NASA Astrophysics Data System (ADS)

    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

  2. The Chemical Composition of Comet C/2012 S1 (ISON) between 1.2 and 0.35 AU of the Sun

    NASA Astrophysics Data System (ADS)

    DiSanti, Michael A.; Bonev, Boncho P.; Gibb, Erika L.; Villanueva, Geronimo L.; Paganini, Lucas; Mumma, Michael J.; Keane, Jacqueline V.; Meech, Karen J.; Blake, Geoff A.; McKay, Adam J.

    2014-11-01

    The apparition of dynamically new, sun-grazing C/2012 S1 (ISON) [1] generated considerable ground- and space-based interest, and provided the rare opportunity to conduct compositional studies to heliocentric distances (Rh) well within 1 AU. We report gas production rates and molecular abundances from high-resolution (λ/Δλ ~ 25,000) spectra on four dates (UT 2013 Oct 22, 24, 25, and Nov 7) using NIRSPEC [2] at Keck 2, and on six dates (Nov 15 through 19, and Nov 22) using CSHELL [3] at the NASA-IRTF. This permitted measuring volatile abundances over a wide range in Rh.NIRSPEC is cross-dispersed and so allows simultaneous measure of trace species together with H2O, thereby avoiding most sources of systematic uncertainty, for example those associated with differences in slit losses and flux calibration among echelle orders. CSHELL has limited spectral coverage per setting, however the IRTF is unique among ground-based IR observatories in allowing daytime observations. This permitted compositional measurements of ISON to a minimum solar elongation angle of 20 degrees.A suite of molecules (H2O, CO, H2CO, CH3OH, C2H6, C2H2, CH4, HCN, NH3) and radicals (OH, NH2) were targeted and detected. Our serial measurements allowed a search for potential changes in molecular abundances relative to H2O. Those of some species (CO, C2H6, CH3OH, CH4) remained relatively constant with Rh, while others (e.g., H2CO, HCN) increased in abundance with decreasing Rh, for example as could result from potential compositional heterogeneity in the nucleus and/or release from increasingly heated grains in the coma. Results from our serial measurements of ISON will be presented and discussed.References: [1] Nevski V. and Novichonok A. (2012) CBET 3238. [2] McLean, I. S., et al. (1998) Proc. SPIE 3354, 566-578. [3] Tokunaga A, et al. (1990) Proc. SPIE, 1235, 131-143. This work is supported through the NASA Planetary Astronomy, Planetary Atmospheres, and Astrobiology Programs, and the National

  3. Synthesis of hydrogen cyanide under simulated hydrothermal conditions

    NASA Astrophysics Data System (ADS)

    Pinedo-González, Paulina

    Nitrogen is a fundamental element for life, where is present in structural (e.g., proteins), catalytic (e.g., enzymes and ribozymes), energy transfer (e.g., ATP) and information storage (RNA and DNA) biomolecules. Atmospheric and planetary models suggest that nitrogen was abundant in the early atmospheres of Earth as dinitrogen (N2 ), an inert gas under normal atmospheric conditions. To be available for prebiotic synthesis it must be converted into hydrogen cyanide (HCN), ammonia (NH3 ) and/or nitric oxide (NO), in a process referred to as nitrogen fixation. Due to the strength of the triple bond in N2 , nitrogen fixation, while thermodynamically favored is kinetically restricted. In a reducing atmosphere dominated by CH4 -N2 , thunderstorm lightning efficiently produces HCN and NH3 (Stribling and Miller, 1987). Nevertheless, photochemical and geochemical constraints strongly suggest that the early atmosphere was weakly reducing, dominated by CO2 and N2 with traces of CH4 , CO, and H2 (Kasting, 1993). Under these conditions, HCN is no longer synthesized in the lightning channel and instead NO is formed (Navarro-Gonźlez, et al., 2001). In volcanic plumes, where magmatic gases a were more reducing than in the atmosphere, NO can also be formed by the lava heat (Mather et al., 2004) or volcanic lightning (Navarro-Gonźlez et al., 1998). Surprisingly, dinitrogen can be a reduced to NH3 in hydrothermal systems (Brandes et al., 1998), but the formation of HCN and its derivates were not investigated. The present work explores the possibility of the formation of HCN as well as other nitrile derivatives catalyzed by mineral surfaces in hydrothermal vents. To simulate a hydrothermal atmosphere, the experiments were carried out in a stainless steel Parr R minireactor with a 0.1 M NH4 HCO3 solution (200 ml) with or without a mineral surface exposed at 1 bar at temperatures ranging from 100 to 375° C. Different mineral matrices are been investigated. Our preliminary results

  4. Cyanide and isocyanide abundances in the cold, dark cloud TMC-1

    NASA Technical Reports Server (NTRS)

    Irvine, W. M.; Schloerb, F. P.

    1984-01-01

    Cold, dark molecular clouds are particularly useful for the study of interstellar chemistry because their physical parameters are better understood than those of heterogeneous, complex giant molecular clouds. Another advantage is their relatively small distance from the solar system. The present investigaation has the objective to provide accurate abundance ratios for several cyanides and isocyanides in order to constrain models of dark cloud chemistry. The relative abundances of such related species can be particularly useful for the study of chemical processes. The cloud TMC-1 considered in the current study has a remarkably high abundance of acetylene and polyacetylene derivatives. Data at 3 mm, corresponding to the J = 1 to 0 transitions of HCN, H(C-13)N, HN(C-13), HC(N-15), and H(N-15)C were obtained.

  5. Prebiotic syntheses of purines and pyrimidines

    NASA Technical Reports Server (NTRS)

    Basile, B.; Oro, J.; Lazcano, A.

    1984-01-01

    The results of experimental and theoretical investigations of the prebiotic synthesis of purines and pyramidines are surveyed. Topics examined include the synthesis of purines from HCN via 4,5-disubstituted imidazole derivatives in aqueous solutions or liquid NH3, simultaneous formation of amino acids and purines by electron irradiation of CH4-NH3-H2O mixtures, synthesis of pyrimadines from cynoacetylene, energetics, formation of bases under anhydrous or concentrated conditions, formation of bases under dilute conditions, Fischer-Tropsch-type reactions, and the role of activated intermediates. It is pointed out that the precursor compounds have been detected in the interstellar medium, on Titan, and in other solar-system bodies, and that solar-nebula HCN concentrations of the order of 1-10 mM have been estimated on the basis of meteorite measurements.

  6. Shock Synthesis in the Atmosphere of Jupiter

    NASA Astrophysics Data System (ADS)

    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.

  7. 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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Paganini, L.; Mumma, M. J.; Villanueva, G. L.

    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 Nançaymore » (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.« less

  8. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Roth, Nathan X.; Gibb, Erika L.; Bonev, Boncho P.

    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 sampledmore » 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.« less

  9. Millimetre observations of comets P/Brorsen-Metcalf (1989o) and Austin (1989c1) with the IRAM 30-m radio telescope

    NASA Technical Reports Server (NTRS)

    Colom, P.; Despois, D.; Bockelee-Morvan, D.; Crovisier, J.; Paubert, G.

    1990-01-01

    Millimeter observations with the IRAM 30 m telescope were conducted in comet P/Brorsen-Metcalf (1989o) on September 1989 and Austin (1989c1) on April and May 1990. The HCN J(1-0) and J(3-2) lines were detected in both comets. The HCN production rate relative to water in P/Brorsen-Metcalf is comparable to that previously measured in comet P/Halley, while that inferred in comet Austin might be smaller by a factor of two. The H2CO(3 sub 12 - 2 sub 11) transition, marginally observed in comet P/Brorsen-Metcalf, was firmly detected in May 1990 in comet Austin. Observations performed at offset positions suggest that the source of H2CO might be distributed. The H2CO abundance is on the order of 0.5 percent that of water for both comets, assuming a scalelength of 10(exp 4) km at 1 AU from the Sun for the distributed source. During the May observing period of comet Austin, two new species were detected for the first time in a comet: hydrogen sulfide (H2S) through its 1(sub 10) - 1(sub 01) ortho line at 169 GHz, and methanol (CH3OH) through J(3-2) delta K = 0 transitions at 145 GHz. Preliminary estimates of their abundances are 1.5 x 10(exp -3) for H2S and 8 x 10(exp -3) for CH3OH.

  10. Was adenine the first purine?

    NASA Technical Reports Server (NTRS)

    Schwartz, Alan W.; Bakker, C. G.

    1989-01-01

    Oligomerization of HCN (1 molar) in the presence of added formaldehyde (0.5 molar) produced an order of magnitude more 8-hydroxymethyladenine than adenine or any other biologically significant purine. This result suggests that on the prebiotic earth, nucleoside analogs may have been synthesized directly in more complex mixtures of HCN with other aldehydes.

  11. Bitopic Sphingosine 1-Phosphate Receptor 3 (S1P3) Antagonist Rescue from Complete Heart Block: Pharmacological and Genetic Evidence for Direct S1P3 Regulation of Mouse Cardiac Conduction.

    PubMed

    Sanna, M Germana; Vincent, Kevin P; Repetto, Emanuela; Nguyen, Nhan; Brown, Steven J; Abgaryan, Lusine; Riley, Sean W; Leaf, Nora B; Cahalan, Stuart M; Kiosses, William B; Kohno, Yasushi; Brown, Joan Heller; McCulloch, Andrew D; Rosen, Hugh; Gonzalez-Cabrera, Pedro J

    2016-01-01

    The molecular pharmacology of the G protein-coupled receptors for sphingosine 1-phosphate (S1P) provides important insight into established and new therapeutic targets. A new, potent bitopic S1P3 antagonist, SPM-354, with in vivo activity, has been used, together with S1P3-knockin and S1P3-knockout mice to define the spatial and functional properties of S1P3 in regulating cardiac conduction. We show that S1P3 is a key direct regulator of cardiac rhythm both in vivo and in isolated perfused hearts. 2-Amino-2-[2-(4-octylphenyl)ethyl]propane-1,3-diol in vivo and S1P in isolated hearts induced a spectrum of cardiac effects, ranging from sinus bradycardia to complete heart block, as measured by a surface electrocardiogram in anesthetized mice and in volume-conducted Langendorff preparations. The agonist effects on complete heart block are absent in S1P3-knockout mice and are reversed in wild-type mice with SPM-354, as characterized and described here. Homologous knockin of S1P3-mCherry is fully functional pharmacologically and is strongly expressed by immunohistochemistry confocal microscopy in Hyperpolarization Activated Cyclic Nucleotide Gated Potassium Channel 4 (HCN4)-positive atrioventricular node and His-Purkinje fibers, with relative less expression in the HCN4-positive sinoatrial node. In Langendorff studies, at constant pressure, SPM-354 restored sinus rhythm in S1P-induced complete heart block and fully reversed S1P-mediated bradycardia. S1P3 distribution and function in the mouse ventricular cardiac conduction system suggest a direct mechanism for heart block risk that should be further studied in humans. A richer understanding of receptor and ligand usage in the pacemaker cells of the cardiac system is likely to be useful in understanding ventricular conduction in health, disease, and pharmacology. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

  12. Effects of acidic pH on voltage-gated ion channels in rat trigeminal mesencephalic nucleus neurons.

    PubMed

    Han, Jin-Eon; Cho, Jin-Hwa; Choi, In-Sun; Kim, Do-Yeon; Jang, Il-Sung

    2017-03-01

    The effects of acidic pH on several voltage-dependent ion channels, such as voltage-dependent K + and Ca 2+ channels, and hyperpolarization-gated and cyclic nucleotide-activated cation (HCN) channels, were examined using a whole-cell patch clamp technique on mechanically isolated rat mesencephalic trigeminal nucleus neurons. The application of a pH 6.5 solution had no effect on the peak amplitude of voltage-dependent K + currents. A pH 6.0 solution slightly, but significantly inhibited the peak amplitude of voltage-dependent K + currents. The pH 6.0 also shifted both the current-voltage and conductance-voltage relationships to the depolarization range. The application of a pH 6.5 solution scarcely affected the peak amplitude of membrane currents mediated by HCN channels, which were profoundly inhibited by the general HCN channel blocker Cs + (1 mM). However, the pH 6.0 solution slightly, but significantly inhibited the peak amplitude of HCN-mediated currents. Although the pH 6.0 solution showed complex modulation of the current-voltage and conductance-voltage relationships, the midpoint voltages for the activation of HCN channels were not changed by acidic pH. On the other hand, voltage-dependent Ca 2+ channels were significantly inhibited by an acidic pH. The application of an acidic pH solution significantly shifted the current-voltage and conductance-voltage relationships to the depolarization range. The modulation of several voltage-dependent ion channels by an acidic pH might affect the excitability of mesencephalic trigeminal nucleus neurons, and thus physiological functions mediated by the mesencephalic trigeminal nucleus could be affected in acidic pH conditions.

  13. The chemical composition of comet C/2012 S1 (ISON) between 1.2 au and 0.35 au from the Sun

    NASA Astrophysics Data System (ADS)

    DiSanti, M.; Bonev, B.; Gibb, E.; Villanueva, G.; Paganini, L.; Mumma, M.; Keane, J.; Meech, K.; Blake, G.; McKay, A.

    2014-07-01

    Introduction: By virtue of their small size and prolonged storage at large heliocentric distances (R_h), comets remain largely preserved. As a result, their ices encode a record of physical and chemical conditions in the early Solar System [1,2]. The recent apparition of C/2012 S1 (ISON) [3], a dynamically new sun-grazing comet, provided a rare opportunity to both prepare for and subsequently conduct compositional studies to well within 1 au from the Sun. Observations: We obtained high-resolution spectra (Resolving Power approximately 25,000) of Comet ISON on four dates (UT 2013 Oct. 22, 24, 25, and Nov. 7) using NIRSPEC [4] at Keck 2, and on six dates (Nov. 15 through 19, and Nov. 22) using CSHELL [5] at the NASA InfraRed Telescope Facility (IRTF). Our observations provided a measure of volatile production rates and abundance ratios (relative to H_2O) over a wide range of heliocentric distances (R_h = 1.23--0.35 au). NIRSPEC is cross-dispersed and so allows for simultaneous measure of multiple trace species together with H_2O, thereby avoiding most sources of systematic uncertainty, for example those associated with differences in slit losses and with flux calibration among settings. CSHELL has limited spectral coverage per setting, requiring judicious targeting of specific molecular emissions that (when possible) simultaneously encompass lines of H_2O and/or OH prompt emission, which serves as a proxy for water production provided equivalent OH line g-factors are known [6]. Despite this limitation, the IRTF is unique among ground-based IR observatories in its ability to conduct observations during daytime. This permitted obtaining compositional measurements of Comet ISON to a minimum solar elongation angle of 20 degrees. These will be discussed, and comparisons will be made with previously-reported results from observations with NIRSPEC [7] and HST [8]. Results: A suite of molecules (H_2O, CO, H_2CO, CH_3OH, C_2H_6, C_2H_2, CH_4, HCN, and NH_3) and radicals (OH

  14. CN radical reactions with hydrogen cyanide and cyanogen - Comparison of theory and experiment

    NASA Technical Reports Server (NTRS)

    Yang, D. L.; Yu, T.; Lin, M. C.; Melius, C. F.

    1992-01-01

    The method of laser photolysis/laser-induced fluorescence is used to obtain absolute rate constants for CN radical reactions with HCN and C2N2. The rate constants were found to be temperature-dependent in the range 300-740 K and pressure independent in the range 100-600 Torr. Rice-Remsperger-Kassel-Marcus theory for both reactions employing the transition state parameters obtained by the BAC-MP4 method are made. These calculations yielded reasonable results for the CN + HCN reaction, predicting both the temperature dependence and pressure independence. No pressure effect was observed in the pressure range 100-1000 Torr at temperatures below 900 K, confirming the experimental results.

  15. Transition from Gaseous Compounds to Aerosols in Titan's Atmosphere

    NASA Technical Reports Server (NTRS)

    Lebonnois, Sebastien; Bakes, E. L. O.; McKay, Christopher P.; DeVincenzi, Donald (Technical Monitor)

    2002-01-01

    We investigate the chemical transition of simple molecules like C2H2 and HCN into aerosol particles in the context of Titan's atmosphere. Experiments that synthesize analogs (tholins) for these aerosols can help understand and constrain these polymerization mechanisms. Using information available from these experiments, we suggest chemical pathways that can link simple molecules to macromolecules, that will be the precursors to aerosol particles: polymers of acetylene and cyanoacetylene, polycyclic aromatics (PAHs), polymers of HCN and other nitriles, and polynes. Although our goal here is not to build a detailed kinetic model for this transition, we propose parameterizations to estimate the production rates of these macromolecules, their C/N and C/H ratios, and the loss of parent molecules (C2H2, HCN, HC3N and other nitriles, C6H6) from the gas phase to the haze. We use a 1-dimensional photochemical model of Titan's atmosphere to estimate the formation rate of precursors macromolecules. We find a production zone slightly lower than 200 km altitude with a total production rate of 4 x 10(exp -14) g/ sq cm s and a C/N approx. = 4. These results are compared with experimental data, and to microphysical models requirements. The Cassini/Huygens mission will bring a detailed picture of the haze distribution and properties, that will be a great challenge for our understanding of those chemical processes.

  16. "Solid State" Chemistry in Titan Ice Particles

    NASA Image and Video Library

    2016-09-20

    Scientists from NASA's Cassini mission suggested in a 2016 paper that the appearance of a cloud of dicyanoacetylene (C4N2) ice in Titan's stratosphere may be explained by "solid-state" chemistry taking place inside ice particles. The particles have an inner layer of cyanoacetylene (HC3N) ice coated with an outer layer of hydrogen cyanide (HCN) ice. Left: When a photon of light penetrates the outer shell, it can interact with the HC3N, producing C3N and H. Center: The C3N then reacts with HCN to yield C4N2 and H (shown at right). Another reaction that also yields C4N2 ice and H also is possible, but the researchers think it is less likely. http://photojournal.jpl.nasa.gov/catalog/PIA20715

  17. Carboxylic Acids as Indicators of Parent Body Conditions

    NASA Technical Reports Server (NTRS)

    Lerner N. R.; Chang, Sherwood (Technical Monitor)

    1995-01-01

    Alpha-hydroxy and alpha-amino carboxylic acids found on the Murchison meteorite are deuterium enriched. It is postulated that they arose from a common interstellar scurce: the reaction of carbonyl compounds in an aqueous mixture containing HCN and NH3. Carbonyl compounds react with HCN to form alpha-hydroxy nitriles, RR'CO + HCN right and left arrow RR'C(OH)CN. If ammonia is also present, the alpha-hydroxy nitriles will exist in equilibrium with the alpha-amino nitriles, RR'C(OH)CN + NH3 right and left arrow - RRCNH2CN + H2O. Both nitrites are hydrolyzed by water to form carboxylic acids: RR'C(OH)CN + H2O yields RR'C(OH)CO2H and RR'C(NH2)CN + H2O yields RR'C(NH2)CO2H.

  18. The Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels: from Biophysics to Pharmacology of a Unique Family of Ion Channels.

    PubMed

    Sartiani, Laura; Mannaioni, Guido; Masi, Alessio; Novella Romanelli, Maria; Cerbai, Elisabetta

    2017-10-01

    Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels are important members of the voltage-gated pore loop channels family. They show unique features: they open at hyperpolarizing potential, carry a mixed Na/K current, and are regulated by cyclic nucleotides. Four different isoforms have been cloned (HCN1-4) that can assemble to form homo- or heterotetramers, characterized by different biophysical properties. These proteins are widely distributed throughout the body and involved in different physiologic processes, the most important being the generation of spontaneous electrical activity in the heart and the regulation of synaptic transmission in the brain. Their role in heart rate, neuronal pacemaking, dendritic integration, learning and memory, and visual and pain perceptions has been extensively studied; these channels have been found also in some peripheral tissues, where their functions still need to be fully elucidated. Genetic defects and altered expression of HCN channels are linked to several pathologies, which makes these proteins attractive targets for translational research; at the moment only one drug (ivabradine), which specifically blocks the hyperpolarization-activated current, is clinically available. This review discusses current knowledge about HCN channels, starting from their biophysical properties, origin, and developmental features, to (patho)physiologic role in different tissues and pharmacological modulation, ending with their present and future relevance as drug targets. Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.

  19. Chemistry and structure of giant molecular clouds in energetic environments

    NASA Astrophysics Data System (ADS)

    Anderson, Crystal Nicole

    2016-09-01

    into the ISM. Under such hostile conditions, we cannot expect star formation to evolve in the same fashion as it does across much of the Galaxy. With the advancement of radio interferometry instruments like ALMA and the ATCA, we are able to observe nearby dwarf galaxies at 1.5-40 pc scales. Also, with the advancement of the instruments, astrochemistry is becoming an exciting and dominant field in studying star forming regions at varying densities and evolutionary stages outside the Galaxy. In this dissertation, I discuss observations of 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 observe anomalously large HCO+/HCN line ratios of >5 for the NGC 5253 SSC, 30Dor-10 and N159W clumps. However the ratio is <2 for N113, the least energetic source, on clump scales. NGC 5253, 30Dor-10 and N159W have anomalously faint HCN. The CMZ however, does not have anomalously faint HCN it actually has HCO+/HCN common of high metallicity environments, active galactic nuclei and ultra luminous infrared galaxies. These observations suggest the reason HCN has fainter emission than HCO+ must be a combination of low metallicity and energetics contributing to the change in the HCO+/HCN ratio. I find that the impact of the massive star forming regions on surrounding gas in different galaxies from small to large scales changes the chemistry within these regions. A more energetic region's chemistry seems to be different from a less energetic region. There is a richer chemistry within a less energetic region; which may suggest that the

  20. Hydrocarbon Chemistry in Planetary Nebulae: Observations of CCH and c-C3H2

    NASA Astrophysics Data System (ADS)

    Schmidt, Deborah Rose; Zack, Lindsay; Ziurys, Lucy M.

    2018-06-01

    In an effort to fully evaluate the molecular content of planetary nebulae (PNe), and the role of hydrocarbons, we have undertaken a search for CCH towards K4–47, K3–58, K3–17, M3–28, M4–14, Hb 5, K3-45, M1-7, M3-55, NGC 2440, NGC 6772, M1-12, and M1-20. These nebulae span a range of kinematic ages and morphologies. In addition, we observed CN, CCH, and c-C3H2 at eight positions sampling the Helix Nebula. Measurements at 3 mm of the N=1→0 transitions of CCH and CN and the J=21,2→10,1 of c-C3H2 were performed using the ALMA prototype 12-M antenna of the Arizona Radio Observatory (ARO), while the N=3→2 transition of CCH at 1 mm was observed using the ARO Sub-Millimeter Telescope. CCH was detected in 9 of the 13 survey PNe, while CCH, CN, and c-C3H2 were observed at all positions in the Helix, often with a complex velocity structure; c-C3H2 was also identified in K4-47. From radiative transfer modeling, column densities for CCH were found to range between Ntot(CCH) ~ 0.2-3.3 × 1015 cm-2 for the survey PNe, corresponding to fractional abundances with respect to H2 of f(CCH) ~ 0.2-47 × 10-7. The CN, CCH, and c-C3H2 column densities across the Helix were estimated to range between Ntot(CN) ~ 6.9-74 × 1011 cm-2, Ntot(CCH) ~ 3.2-28 × 1011 cm-2, and Ntot(c-C3H2) ~ 0.2-4.7 × 1011 cm-2, with fractional abundances of f(CN) ~ 0.9-9.8 × 10-7, f(CCH) ~ 0.4-3.7 × 10-7, and f(c-C3H2) ~ 0.3-6.5 × 10-8. Based on HCN measurements of the Helix by Schmidt & Ziurys (2017a), [CN]/[HCN] ratios are ~1-34, while [CCH]/[c-C3H2] ratios varied between ~3-46. The abundance of CCH in all observed PNe did not vary significantly across the nebular lifespan of ~10,000 years, in contrast to model predictions. These abundances are ~1-2 orders of magnitude greater than those measured in the diffuse ISM; moreover, the [CN]/[HCN] and [CCH]/[c-C3H2] ratios observed in the Helix are comparable to those in diffuse clouds, striking evidence that molecular material ejected from PNe

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kawakita, Hideyo; Kobayashi, Hitomi; Russo, Neil Dello

    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{submore » 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.« less

  2. KCNE Regulation of K+ Channel Trafficking – a Sisyphean Task?

    PubMed Central

    Kanda, Vikram A.; Abbott, Geoffrey W.

    2012-01-01

    Voltage-gated potassium (Kv) channels shape the action potentials of excitable cells and regulate membrane potential and ion homeostasis in excitable and non-excitable cells. With 40 known members in the human genome and a variety of homomeric and heteromeric pore-forming α subunit interactions, post-translational modifications, cellular locations, and expression patterns, the functional repertoire of the Kv α 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 α subunit partners. PMID:22754540

  3. Isotopic disproportionation during hydrogen isotopic analysis of nitrogen-bearing organic compounds

    USGS Publications Warehouse

    Nair, Sreejesh; Geilmann, Heike; Coplen, Tyler B.; Qi, Haiping; Gehre, Matthias; Schimmelmann, Arndt; Brand, Willi A.

    2015-01-01

    Rationale High-precision hydrogen isotope ratio analysis of nitrogen-bearing organic materials using high-temperature conversion (HTC) techniques has proven troublesome in the past. Formation of reaction products other than molecular hydrogen (H2) has been suspected as a possible cause of incomplete H2 yield and hydrogen isotopic fractionation. Methods The classical HTC reactor setup and a modified version including elemental chromium, both operated at temperatures in excess of 1400 °C, have been compared using a selection of nitrogen-bearing organic compounds, including caffeine. A focus of the experiments was to avoid or suppress hydrogen cyanide (HCN) formation and to reach quantitative H2 yields. The technique also was optimized to provide acceptable sample throughput. Results The classical HTC reaction of a number of selected compounds exhibited H2 yields from 60 to 90 %. Yields close to 100 % were measured for the experiments with the chromium-enhanced reactor. The δ2H values also were substantially different between the two types of experiments. For the majority of the compounds studied, a highly significant relationship was observed between the amount of missing H2and the number of nitrogen atoms in the molecules, suggesting the pyrolytic formation of HCN as a byproduct. A similar linear relationship was found between the amount of missing H2 and the observed hydrogen isotopic result, reflecting isotopic fractionation. Conclusions The classical HTC technique to produce H2 from organic materials using high temperatures in the presence of glassy carbon is not suitable for nitrogen-bearing compounds. Adding chromium to the reaction zone improves the yield to 100 % in most cases. The initial formation of HCN is accompanied by a strong hydrogen isotope effect, with the observed hydrogen isotope results on H2 being substantially shifted to more negative δ2H values. The reaction can be understood as an initial disproportionation leading to H2 and HCN

  4. Photochemistry of Pluto's atmosphere and ionosphere near perihelion

    NASA Astrophysics Data System (ADS)

    Krasnopolsky, Vladimir A.; Cruikshank, Dale P.

    1999-09-01

    We consider Pluto's photochemistry using a background model for a hydrodynamically escaping atmosphere by Krasnopolsky [1999]. Some adjustments are made in the basic continuity equation and in the boundary conditions to account for hydrodynamic flow in the atmosphere. We model the photochemistry for 44 neutral and 23 ion species. Because of the high methane mixing ratio, Pluto's photochemistry is more similar to that of Titan than that of Triton. Charge exchange between N2+ and CH4 significantly reduces the production of atomic nitrogen. The most abundant photochemical products are C2H2(3×1017), C4H2(1017), HCN(6×1016), H2(4×1016), C2H4(4×1016), HC3N(3.4×1016), C2H6(2×1016), C3H2(9×1015), and C3H4 (8×1015, all in cm-2). In addition to the parent N2, CH4, and CO molecules which absorb photons with λ<145nm, these products absorb almost completely photons with λ<185nm, therefore significantly increasing the number of dissociation events. Photochemical losses of the parent species are much smaller than their escape. Precipitation rates are the highest for C2H2, C4H2, HC3N, HCN, C2H6, and C2H4 (65, 58, 23, 14, 9, and 6 g cm-2 Byr-1, respectively, reduced by a factor of 3 to account for seasonal variations). Escape of photochemical products is highest for H2, H, C2H2, C2H4, HCN, and N(2×1026, 1.4×1026, 6×1024, 3.6×1024, 2.3×1024, and 1.8×1024s-1, respectively). The electron density reaches a maximum of 800 cm-3 at 2250 km. The most abundant ions are HCNH+, C3H3+, and C3H5+. Some of the photochemical products might be detected using the technique of UV solar occultation spectroscopy from a spacecraft flyby.

  5. Intoxication by cyanide in fires: a study in monkeys using polyacrylonitrile

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Purser, D.A.; Grimshaw, P.; Berrill, K.R.

    It is suspected that hydrogen cyanide (HCN) may be an important factor in incapacitating fire victims, but the effects of sublethal exposures are not well characterized. Also, the incapacitating effects of fire atmospheres result from exposure to a mixture of toxic products so that the contribution from each component is difficult to determine. The mechanisms of incapacitation in monkeys exposed to the pyrolysis products of polyacrylonitrile (PAN) were compared to those resulting from low level HCN gas exposures. The physiological effects of the PAN atmospheres were almost identical to those of HCN gas alone. They consisted of hyperventilation, followed bymore » loss of consciousness after 1-5 min, bradycardia with arrhythmias and T-wave abnormalities, and were followed by a rapid recovery after exposure. Hydrogen cyanide is considered to be the major toxic product formed by the pyrolysis of PAN. It is suggested that HCN may produce rapid incapacitation at low blood levels of cyanide in fires, while death may occur later due to carbon monoxide poisoning or other factors.« less

  6. Parent volatiles in comet 9P/Tempel 1: before and after impact

    NASA Technical Reports Server (NTRS)

    Mumma, Michael J.; DiSanti, Michael A.; Magee-Sauer, Karen; Bonev, Boncho P.; Villanueva, Geronimo L.; Kawakita, Hideyo; Dello Russo, Neil; Gibb, Erika L.; Blake, Geoffrey A.; Lyke, James E.; hide

    2005-01-01

    We quantified eight parent volatiles (H2O, C2H6, HCN, CO, CH3OH, H2CO, C2H2, and CH4) in the Jupiter-family comet Tempel 1 using high-dispersion infrared spectroscopy in the wavelength range 2.8 to 5.0 micrometers. The abundance ratio for ethane was significantly higher after impact, whereas those for methanol and hydrogen cyanide were unchanged. The abundance ratios in the ejecta are similar to those for most Oort cloud comets, but methanol and acetylene are lower in Tempel 1 by a factor of about 2. These results suggest that the volatile ices in Tempel 1 and in most Oort cloud comets originated in a common region of the protoplanetary disk.

  7. Water, hydrogen cyanide, and dust production from the distant comet 29P/Scwassmann-Wachmann 1

    NASA Astrophysics Data System (ADS)

    Bockelee-Morvan, D.; Biver, N.; Opitom, C.; Hutsemekers, D.; Crovisier, J.; Jehin, E.; Hartogh, P.; Szutowizc, S.; Lellouch, E.; Kidger, M.; Vandenbussche, B.; Zakharov, V.; HSSO Team

    2014-07-01

    Comet 29P/Schwassmann-Wachmann is a periodic comet, also classified as a Centaur, orbiting on a nearly circular orbit at 6 au from the Sun. It is well known for its permanent activity driven by CO outgassing, and its episodic outbursts. Comet 29P was observed in 2010--2011 with the Herschel space observatory. Observations of water and ammonia were performed with the Heterodyne Instrument for the Far-Infrared (HIFI). One set of measurements was obtained two days after a major outburst (16 Apr. 2010). Images of the dust coma at 70 and 160 μ m were obtained using the Photodetector Array Camera and Spectrometer (PACS). To support these observations, observations of CO and HCN were undertaken at the 30-m telescope of the Institut de radioastronomie millimétrique (IRAM). We present an overview of this set of observations. H_2O and CO are detected. We also obtain the first detection of HCN in this distant comet. Relative abundances are similar to those measured in the coma of comet C/1995 O1 (Hale-Bopp) when at r_h = 6 au from the Sun, but strongly differ from coma compositions at r_h = 1 au. The line profiles show evidence that both H_2O, HCN are released from long-lived icy grains. Detailed modeling of water production from icy-grain suggests continuous release of icy grains from the nucleus. The thermal emission from the nucleus is detected in the PACS 70 μ m images. The thermal emission from dust grains is analyzed with a thermal model of dust emission, which takes into account the dust size distribution. Both the size index and the dust production rate are measured.

  8. Ion-molecule reactions relevant to Titan's ionosphere.

    NASA Astrophysics Data System (ADS)

    McEwan, M. J.; Scott, G. B. I.; Anicich, V. G.

    1998-02-01

    Twenty four new ion-molecule reactions are presented for inclusion in the modeling of the ionosphere of Saturn's satellite Titan. Sixteen reactions were re-examined to reduce uncertainties in the previous literature results. In this study the authors have examined the reactions of N+ and N2+ with CH4, C2H2, C2H4, C2H6, HCN, CH2CHCN and HC3N; the reaction of N+ with CH3CN; the reactions of C3H5+ with CH4, C2H2 C2H4, C2H6, H2, HCN, HC3N and CH2CHCN; the reactions of C2N2+ with C2H2; C2H2+ and C2N2; C2H4 with C2H3+, C2H4+, CHCCNH+, and HC5N+; HCNH+ with C2H6; C3H6+ with C3H6; HCN with C2H6+, C3H6+, c-C3H6+, C2N2+ and NO+; N2 with C2H2+ and C2H5+; C2H4+ and HC3N. The ions selected for this study were derived either from nitrogen, appropriate hydrocarbons or nitriles. The reactant neutrals were selected on the basis of their known presence in Titan's atmosphere. The reaction products are consistent with the expected increase in ion size through ion-molecule reaction processing. Data are also presented for the reactions of 23 ions with molecular nitrogen. Almost all of these ions are unreactive with N2.

  9. 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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cordiner, M. A.; Milam, S. N.; Mumma, M. J.

    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 ismore » 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.« less

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

    PubMed

    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

  11. Simultaneous gas chromatographic determination of four toxic gases generally present in combustion atmospheres.

    PubMed

    Endecott, B R; Sanders, D C; Chaturvedi, A K

    1996-01-01

    The measurement of combustion gases produced by burning aircraft cabin materials poses a continuing limitation for smoke toxicity research. Because toxic effects of gases depend on both their concentrations and the duration of exposure, frequent atmosphere sampling is necessary to define the gas concentration-exposure time curve. A gas chromatographic (GC) method was developed for the simultaneous analyses of carbon monoxide (CO), hydrogen sulfide (H2S), sulfur dioxide (SO2), and hydrogen cyanide (HCN). The method used an MTI M200 dual-column gas chromatograph equipped with 4-m molecular sieve-5A and 8-m PoraPlot-U wall-coated capillary columns and two low-volume, high-sensitivity thermal conductivity detectors. Detectability (in parts per million [ppm]) and retention times (in seconds) for the gases were as follows: CO, 100 ppm, 28 s; H2S, 50 ppm, 26 s; SO2, 125 ppm, 76 s; and HCN, 60 ppm, 108 s. The method was effective for determining these gases in mixtures and in the combustion atmospheres generated by burning wool (CO, HCN, and H2S) and modacrylic fabrics (CO and HCN). Common atmospheric gaseous or combustion products (oxygen, carbon dioxide, nitrogen, water vapor, and other volatiles) did not interfere with the analyses. However, filtration of the combustion atmospheres was necessary to prevent restriction of the GC sampling inlet by smoke particulates. The speed, sensitivity, and selectivity of this method make it suitable for smoke toxicity research and for evaluating performance of passenger protective breathing equipment. Also, this method can potentially be modified to analyze these gases when they are liberated from biosamples.

  12. Electron Excitation of High Dipole Moment Molecules

    NASA Astrophysics Data System (ADS)

    Goldsmith, Paul; Kauffmann, Jens

    2018-01-01

    Emission from high-dipole moment molecules such as HCN allows determination of the density in molecular clouds, and is often considered to trace the “dense” gas available for star formation. We assess the importance of electron excitation in various environments. The ratio of the rate coefficients for electrons and H2 molecules, ~10^5 for HCN, yields the requirements for electron excitation to be of practical importance if n(H2) < 10^{5.5} /cm3 and X(e-) > 10^{-5}, where the numerical factors reflect critical values n_c(H2) and X^*(e-). This indicates that in regions where a large fraction of carbon is ionized, X(e-) will be large enough to make electron excitation significant. The situation is in general similar for other “high density tracers”, including HCO+, CN, and CS. But there are significant differences in the critical electron fractional abundance, X^*(e-), defined by the value required for equal effect from collisions with H2 and e-. Electron excitation is, for example, unimportant for CO and C+. Electron excitation may be responsible for the surprisingly large spatial extent of the emission from dense gas tracers in some molecular clouds (Pety et al. 2017, Kauffmann, Goldsmith et al. 2017, A&A, submitted). The enhanced estimates for HCN abundances and HCN/CO and HCN/HCO+ ratios observed in the nuclear regions of luminous galaxies may be in part a result of electron excitation of high dipole moment tracers. The importance of electron excitation will depend on detailed models of the chemistry, which may well be non-steady state and non--static.

  13. [Ca2+]i Elevation and Oxidative Stress Induce KCNQ1 Protein Translocation from the Cytosol to the Cell Surface and Increase Slow Delayed Rectifier (IKs) in Cardiac Myocytes*

    PubMed Central

    Wang, Yuhong; Zankov, Dimitar P.; Jiang, Min; Zhang, Mei; Henderson, Scott C.; Tseng, Gea-Ny

    2013-01-01

    Our goals are to simultaneously determine the three-dimensional distribution patterns of KCNQ1 and KCNE1 in cardiac myocytes and to study the mechanism and functional implications for variations in KCNQ1/KCNE1 colocalization in myocytes. We monitored the distribution patterns of KCNQ1, KCNE1, and markers for subcellular compartments/organelles using immunofluorescence/confocal microscopy and confirmed the findings in ventricular myocytes by directly observing fluorescently tagged KCNQ1-GFP and KCNE1-dsRed expressed in these cells. We also monitored the effects of stress on KCNQ1-GFP and endoplasmic reticulum (ER) remodeling during live cell imaging. The data showed that 1) KCNE1 maintained a stable cell surface localization, whereas KCNQ1 exhibited variations in the cytosolic compartment (striations versus vesicles) and the degree of presence on the cell surface; 2) the degree of cell surface KCNQ1/KCNE1 colocalization was positively correlated with slow delayed rectifier (IKs) current density; 3) KCNQ1 and calnexin (an ER marker) shared a cytosolic compartment; and 4) in response to stress ([Ca2+]i elevation, oxidative overload, or AT1R stimulation), KCNQ1 exited the cytosolic compartment and trafficked to the cell periphery in vesicles. This was accompanied by partial ER fragmentation. We conclude that the cellular milieu regulates KCNQ1 distribution in cardiac myocytes and that stressful conditions can increase IKs by inducing KCNQ1 movement to the cell surface. This represents a hitherto unrecognized mechanism by which IKs fulfills its function as a repolarization reserve in ventricular myocytes. PMID:24142691

  14. High angular resolution mm- and submm-observations of dense molecular gas in M82

    NASA Technical Reports Server (NTRS)

    Wild, W.; Eckart, Andreas; Genzel, Reinhard; Harris, Andrew I.; Jackson, James M.; Jaffe, D. T.; Lugten, J. B.; Stutzki, J.

    1990-01-01

    Researchers observed CO(7-6), CO(3-2), HCN(3-2) and HCO+(3-2) line emission toward the starburst nucleus of M82 and have obtained an upper limit to H13CN(3-2). These are the first observations of the CO(7-6), HCN(3-2) and HCO+(3-2) lines in any extragalactic source. Researchers took the CO(7-6) spectrum in January 1988 at the Infrared Telescope Facility (IRTF) with the Max Planck Institute for Extraterrestrial Physics/Univ. of California, Berkeley 800 GHz Heterodyne Receiver. In March 1989 researchers used the Institute for Radio Astronomy in the Millimeter range (IRAM) 30 m telescope to observe the CO(3-2) line with the new MPE 350 GHz Superconductor Insulator Superconductor (SIS) receiver and the HCN(3-2) and HCO+(3-2) lines with the (IRAM) 230 GHz SIS receiver (beam 12" FWHM, Blundell et al. 1988). The observational parameters are summarized.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bigiel, F.; Leroy, A. K.; Blitz, L.

    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(21), 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 formationmore » 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.« less

  17. Hydrogen Cyanide In Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    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.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chung, Dongwoo T.; Li, Tony Y.; Viero, Marco P.

    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 ourmore » 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%.« less

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chung, Dongwoo T.; Li, Tony Y.; Viero, Marco P.

    Here, 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 formore » 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%.« less

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

    DOE PAGES

    Chung, Dongwoo T.; Li, Tony Y.; Viero, Marco P.; ...

    2017-08-31

    Here, 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 formore » 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%.« less

  1. Tailoring the structure of metal oxide nanostructures towards enhanced sensing properties for environmental applications.

    PubMed

    Yang, Mingqing; He, Junhui

    2012-02-15

    The present article reviews recent works in our laboratory about the sensing properties to toxic gases using nanostructured WO(3), TiO(2), FTiO(2), and CuO functionalized quartz crystal microbalance (QCM) sensors. WO(3) and TiO(2) functionalized QCM sensors have much shorter response time than those functionalized by conventional hydrogen-bond acidic branched copolymers for detection of dimethyl methylphosphonate (DMMP). FTiO(2) functionalized QCM sensors can improve the gas sensing characteristics by shortening the response time but at the price of partial irreversibility. The sensing mechanism was examined by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Varied CuO nanostructures were synthesized by simple modulation of reaction conditions. All the as-prepared CuO was applied on QCM resonators and explored for HCN sensing. Surprisingly, responses of all the sensors to HCN were found to be in an opposite direction as compared with other common volatile substances, offering excellent selectivity for HCN detection. The sensitivity was very high, and the response and recovery were very fast. Comparison of the specific surface areas of CuO nanostructures showed that CuO of higher surface area is more sensitive than that of lower surface area, indicating that the specific surface area of these CuO nanostructures plays an important role in the sensitivity of related sensors. Based on experimental results, a sensing mechanism was proposed in which a surface redox reaction occurs between CuO and Cu(2)O on the CuO nanostructures reversibly upon contact with HCN and air, respectively. The CuO functionalized QCM sensors are considered to be a promising candidate for trace HCN gas detection in practical applications. Copyright © 2011 Elsevier Inc. All rights reserved.

  2. CryoEM structure of a prokaryotic cyclic nucleotide-gated ion channel

    PubMed Central

    James, Zachary M.; Borst, Andrew J.; Haitin, Yoni; Frenz, Brandon; DiMaio, Frank; Zagotta, William N.; Veesler, David

    2017-01-01

    Cyclic nucleotide-gated (CNG) and hyperpolarization-activated cyclic nucleotide-regulated (HCN) ion channels play crucial physiological roles in phototransduction, olfaction, and cardiac pace making. These channels are characterized by the presence of a carboxyl-terminal cyclic nucleotide-binding domain (CNBD) that connects to the channel pore via a C-linker domain. Although cyclic nucleotide binding has been shown to promote CNG and HCN channel opening, the precise mechanism underlying gating remains poorly understood. Here we used cryoEM to determine the structure of the intact LliK CNG channel isolated from Leptospira licerasiae—which shares sequence similarity to eukaryotic CNG and HCN channels—in the presence of a saturating concentration of cAMP. A short S4–S5 linker connects nearby voltage-sensing and pore domains to produce a non–domain-swapped transmembrane architecture, which appears to be a hallmark of this channel family. We also observe major conformational changes of the LliK C-linkers and CNBDs relative to the crystal structures of isolated C-linker/CNBD fragments and the cryoEM structures of related CNG, HCN, and KCNH channels. The conformation of our LliK structure may represent a functional state of this channel family not captured in previous studies. PMID:28396445

  3. Removal of NO in NO/N2, NO/N2/O2, NO/CH4/N2, and NO/CH4/O2/N2 systems by flowing microwave discharges.

    PubMed

    Hueso, José L; Gonzalez-Elipe, Agustín R; Cotrino, José; Caballero, Alfonso

    2007-02-15

    In this paper, continuing previous work, we report on experiments carried out to investigate the removal of NO from simulated flue gas in nonthermal plasmas. The plasma-induced decomposition of small concentrations of NO in N2 used as the carrier gas and O2 and CH4 as minority components has been studied in a surface wave discharge induced with a surfatron launcher. The reaction products and efficiency have been monitored by mass spectrometry as a function of the composition of the mixture. NO is effectively decomposed into N2 and O2 even in the presence of O2, provided always that enough CH4 is also present in the mixture. Other majority products of the plasma reactions under these conditions are NH3, CO, and H2. In the absence of O2, decomposition of NO also occurs, although in that case HCN accompanies the other reaction products as a majority component. The plasma for the different reaction mixtures has been characterized by optical emission spectroscopy. Intermediate excited species of NO*, C*, CN*, NH*, and CH* have been monitored depending on the gas mixture. The type of species detected and their evolution with the gas composition are in agreement with the reaction products detected in each case. The observations by mass spectrometry and optical emission spectroscopy are in agreement with the kinetic reaction models available in literature for simple plasma reactions in simple reaction mixtures.

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

    NASA Astrophysics Data System (ADS)

    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

  5. MALATANG: MApping the dense moLecular gAs in the sTrongest stAr-formiNg Galaxies

    NASA Astrophysics Data System (ADS)

    Gao, Yu; Zhang, Zhiyu; Greve, Thomas; MALATANG Team

    2017-01-01

    The MALATANG Large Program is a 390 hr campaign, using the heterodyne array HARP on the JCMT to map theHCN and HCO+ J = 4 - 3 line emission in 23 of the nearest IR-brightest galaxies beyond the Local Group. Theobservations will reach a sensitivity of 0.3 K km/s (~ 4.5 x 10^6 Msun) at linear resolutions of 0.2-2.8kpc. It is thefirst survey to systematically map the distribution of dense molecular gas out to large galactocentric distances in a statisticallysignificant sample of nearby galaxies. MALATANG will bridge the gap, in terms of physical scale and luminosity,between extragalactic (i.e., galaxy-integrated) and Galactic (i.e., single molecular clouds) observations. A primarygoal of the survey is to delineate for the first time the distributed dense gas star-formation relations, as traced by theHCN and HCO+ J = 4-3, on scales of ~1kpc across our targets. Exploring the behaviour of these star-formationrelations in low surface density regions found in the disks as well as in the nuclear regions where surface densitiesare high, will shed new light on whether such environments are host to fundamentally different star-formation modes.The MALATANG data products of resolved HCN and HCO+ J = 4-3 maps of 23 IR-bright local galaxies, will beof great value to the extragalactic community and, in and of themselves, carry significant legacy value. At the moment,about 50% (~195hrs) of the 390hrs of time allocated to MALATANG has been observed. We here show somevery preliminary results as well after introducing our project.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Paganini, L.; Mumma, M. J.; Villanueva, G. L.

    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, andmore » 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.« less

  7. Electrophysiological properties of prion-positive cardiac progenitors derived from murine embryonic stem cells.

    PubMed

    Fujii, Hiroshi; Ikeuchi, Yu; Kurata, Yasutaka; Ikeda, Nobuhito; Bahrudin, Udin; Li, Peili; Nakayama, Yuji; Endo, Ryo; Hasegawa, Akira; Morikawa, Kumi; Miake, Junichiro; Yoshida, Akio; Hidaka, Kyoko; Morisaki, Takayuki; Ninomiya, Haruaki; Shirayoshi, Yasuaki; Yamamoto, Kazuhiro; Hisatome, Ichiro

    2012-01-01

    The prion protein (PrP) has been reported to serve as a surface maker for isolation of cardiomyogenic progenitors from murine embryonic stem (ES) cells. Although PrP-positive cells exhibited automaticity, their electrophysiological characteristics remain unresolved. The aim of the present study was therefore to investigate the electrophysiological properties of PrP-positive cells in comparison with those of HCN4p-or Nkx2.5-positive cells. Differentiation of AB1, HCN5p-EGFP and hcgp7 ES cells into cardiac progenitors was induced by embryoid body (EB) formation. EBs were dissociated and cells expressing PrP, HCN4-EGFP and/or Nkx2.5-GFP were collected via flow cytometry. Sorted cells were subjected to reverse transcriptase-polymerase chain reaction, immunostaining and patch-clamp experiments. PrP-positive cells expressed mRNA of undifferentiation markers, first and second heart field markers, and cardiac-specific genes and ion channels, indicating their commitment to cardiomyogenic progenitors. PrP-positive cells with automaticity showed positive and negative chronotropic responses to isoproterenol and carbamylcholine, respectively. Hyperpolarization-activated cation current (I(f)) was barely detectable, whereas Na(+) and L-type Ca(2+) channel currents were frequently observed. Their spontaneous activity was slowed by inhibition of sarcoplasmic reticulum Ca(2+) uptake and release but not by blocking I(f). The maximum diastolic potential of their spontaneous firings was more depolarized than that of Nkx2.5-GFP-positive cells. PrP-positive cells contained cardiac progenitors that separated from the lineage of sinoatrial node cells. PrP can be used as a marker to enrich nascent cardiac progenitors.

  8. Origin of Cyanide in Cultures of a Psychrophilic Basidiomycete1

    PubMed Central

    Stevens, Dennis L.; Strobel, Gary A.

    1968-01-01

    An unidentified psychrophilic basidiomycete used valine and isoleucine as precursors to hydrocyanic acid (HCN). As probable intermediates in the pathway from valine and isoleucine two cyanogenic glucosides, linamarin and lotaustralin, were demonstrated in fungus cultures. The fungus contained two β-glucosidases and an oxynitrilase which, acting together, were capable of releasing cyanide from both linamarin and lotaustralin. The two β-glucosidases were purified and compared as to pH optimum, Michaelis constant, energy of activation, thermal stability, and substrate specificity. The products of methyl ethyl ketone cyanohydrin and acetone cyanohydrin dissociation by the oxynitrilase were demonstrated to be HCN together with methyl ethyl ketone and acetone, respectively. The oxynitrilase attacked aliphatic hydroxynitriles, but showed no activity on aromatic hydroxynitriles. Images PMID:5651322

  9. Hydrogen Cyanide in the Rhizosphere: Not Suppressing Plant Pathogens, but Rather Regulating Availability of Phosphate

    PubMed Central

    Rijavec, Tomaž; Lapanje, Aleš

    2016-01-01

    Plant growth promoting rhizobacteria produce chemical compounds with different benefits for the plant. Among them, HCN is recognized as a biocontrol agent, based on its ascribed toxicity against plant pathogens. Based on several past studies questioning the validity of this hypothesis, we have re-addressed the issue by designing a new set of in vitro experiments, to test if HCN-producing rhizobacteria could inhibit the growth of phytopathogens. The level of HCN produced by the rhizobacteria in vitro does not correlate with the observed biocontrol effects, thus disproving the biocontrol hypothesis. We developed a new concept, in which HCN does not act as a biocontrol agent, but rather is involved in geochemical processes in the substrate (e.g., chelation of metals), indirectly increasing the availability of phosphate. Since this scenario can be important for the pioneer plants living in oligotrophic alpine environments, we inoculated HCN producing bacteria into sterile mineral sand together with germinating plants and showed that the growth of the pioneer plant French sorrel was increased on granite-based substrate. No such effect could be observed for maize, where plantlets depend on the nutrients stored in the endosperm. To support our concept, we used KCN and mineral sand and showed that mineral mobilization and phosphate release could be caused by cyanide in vitro. We propose that in oligotrophic alpine environments, and possibly elsewhere, the main contribution of HCN is in the sequestration of metals and the consequential indirect increase of nutrient availability, which is beneficial for the rhizobacteria and their plant hosts. PMID:27917154

  10. Poster 8: ALMA observations of Titan : Vertical and spatial distributions of nitriles

    NASA Astrophysics Data System (ADS)

    Moreno, Raphael; Lellouch, Emmanuel; Vinatier, Sandrine; Gurwell, Mark; Moullet, Arielle; Lara, Luisa; Hidayat, Taufiq

    2016-06-01

    We report submm observations of Titan performed with the ALMA interferometer centered at the rotational frequencies of HCN(4-3) and HNC(4-3), i.e. 354 and 362 GHz. These measurements yielded disk-resolved emission spectra of Titan with an angular resolution of ˜0.47". Titan's angular surface diameter was 0.77". Data were acquired in summer 2012 near the greatest eastern and western elongations of Titan at a spectral resolution of 122 kHz (λ/dλ = 3106). We will present radiative transfer analysis of the acquired spectra. With the combination of all the detected rotational lines, we will constrain the atmospheric temperature, the spatial and vertical distribution HCN, HC3N, CH3CN, HNC, C2H5CN, as well as isotopic ratios.

  11. Atlas of Absorption Lines from 0 to 17900 cm-1

    DTIC Science & Technology

    1987-09-01

    Hampton, Virginia H. M. Pickett Jet Propulsion Laboratory Pasadena, California D. J. Richardson and J. S. Namkung ST Systems Corporation (STX...2 NH3 HN03 OH HF HCi HBr HI CIO OCS H2CO H0C1 N2 HCN CH3C! H202 C2H2 C2H6 PH3 Oj(JPL) +- 0(3P)(JPL) H02(JPL) Solor CO...Hanscom AFB, Massachusetts. H. M. Pickett: Jet Propulsion Laboratory, Pasadena, California. D. J. Richardson and J. S. Namkung: ST Systems Corporation

  12. Development of a multiple gas analyzer using cavity ringdown spectroscopy for use in advanced fire detection.

    PubMed

    Fallows, Eric A; Cleary, Thomas G; Miller, J Houston

    2009-02-01

    A portable cavity ringdown spectroscopy (CRDS) apparatus was used to detect effluents from small test fires in the Fire Emulator/Detector Evaluator (FE/DE) and a small room in the Building Fire and Research Laboratory at the National Institute of Standards and Technology (NIST). The output from two lasers is combined to detect four combustion gases, CO, CO(2), HCN, and C(2)H(2), near simultaneously using CRDS. The goal of this work was to demonstrate the feasibility of using a CRDS sensor as a fire detector. Fire effluents were extracted from several test facilities and measurements of CO, CO(2), HCN, and C(2)H(2) were obtained every 25-30 s. In the FE/DE test, peak concentrations of the gases from smoldering paper were 420 parts in 10(6) (ppm) CO, 1600 ppm CO(2), 530 parts in 10(9) (ppb) HCN, and 440 ppb C(2)H(2). Peak gas concentrations from the small room were 270 ppm CO, 2100 ppm CO(2), and 310 ppb C(2)H(2).

  13. The role of NH3 and hydrocarbon mixtures in GaN pseudo-halide CVD: a quantum chemical study.

    PubMed

    Gadzhiev, Oleg B; Sennikov, Peter G; Petrov, Alexander I; Kachel, Krzysztof; Golka, Sebastian; Gogova, Daniela; Siche, Dietmar

    2014-11-01

    The prospects of a control for a novel gallium nitride pseudo-halide vapor phase epitaxy (PHVPE) with HCN were thoroughly analyzed for hydrocarbons-NH3-Ga gas phase on the basis of quantum chemical investigation with DFT (B3LYP, B3LYP with D3 empirical correction on dispersion interaction) and ab-initio (CASSCF, coupled clusters, and multireference configuration interaction including MRCI+Q) methods. The computational screening of reactions for different hydrocarbons (CH4, C2H6, C3H8, C2H4, and C2H2) as readily available carbon precursors for HCN formation, potential chemical transport agents, and for controlled carbon doping of deposited GaN was carried out with the B3LYP method in conjunction with basis sets up to aug-cc-pVTZ. The gas phase intermediates for the reactions in the Ga-hydrocarbon systems were predicted at different theory levels. The located π-complexes Ga…C2H2 and Ga…C2H4 were studied to determine a probable catalytic activity in reactions with NH3. A limited influence of the carbon-containing atmosphere was exhibited for the carbon doping of GaN crystal in the conventional GaN chemical vapor deposition (CVD) process with hydrocarbons injected in the gas phase. Our results provide a basis for experimental studies of GaN crystal growth with C2H4 and C2H2 as auxiliary carbon reagents for the Ga-NH3 and Ga-C-NH3 CVD systems and prerequisites for reactor design to enhance and control the PHVPE process through the HCN synthesis.

  14. Monitor Variability of Millimeter Lines in IRC+10216

    NASA Astrophysics Data System (ADS)

    He, J. H.; Dinh-V-Trung; Hasegawa, T. I.

    2017-08-01

    A single dish monitoring of millimeter maser lines SiS J = 14-13 and HCN {ν }2={1}f J = 3-2 and several other rotational lines is reported for the archetypal carbon star IRC+10216. Relative line strength variations of 5% ∼ 30% are found for eight molecular line features with respect to selected reference lines. Definite line-shape variations are found in limited velocity intervals of the SiS and HCN line profiles. The asymmetrical line profiles of the two lines are mainly due to the varying components. The dominant varying components of the line profiles have similar periods and phases to the IR light variation, though both quantities show some degree of velocity dependence; there is also variability asymmetry between the blue and red line wings of both lines. Combining the velocities and amplitudes with a wind velocity model, we suggest that the line profile variations are due to SiS and HCN masing lines emanating from the wind acceleration zone. The possible link of the variabilities to thermal, dynamical, and/or chemical processes within or under this region is also discussed.

  15. Nitrogen Chemistry in Titan's Upper Atmosphere

    NASA Technical Reports Server (NTRS)

    McKay, Christopher P.; Cuzzi, Jeffrey (Technical Monitor)

    1996-01-01

    In Titan's upper atmosphere N2 is dissociated to N by solar UV and high energy electrons. This flux of N provides for interesting organic chemistry in the lower atmosphere of Titan. Previously the main pathway for the loss of this N was thought to be the formation of HCN, followed by diffusion of this HCN to lower altitudes leading ultimately to condensation. However, recent laboratory simulations of organic chemistry in Titan's atmosphere suggest that formation of the organic haze may be an important sink for atmospheric N. Because estimates of the eddy diffusion profile on Titan have been based on the HCN profile, inclusion of this additional sink for N will affect estimates for all transport processes in Titan's atmosphere. This and other implications of this sink for the N balance on Titan are considered.

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

    NASA Astrophysics Data System (ADS)

    Sun, Youwen; Palm, Mathias; Liu, Cheng; Hase, Frank; Griffith, David; Weinzierl, Christine; Petri, Christof; Wang, Wei; Notholt, Justus

    2018-05-01

    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 negligible.

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

    PubMed

    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.

  18. Short versus long term effects of cyanide on sugar metabolism and transport in dormant walnut kernels.

    PubMed

    Gerivani, Zahra; Vashaee, Elham; Sadeghipour, Hamid Reza; Aghdasi, Mahnaz; Shobbar, Zahra-Sadat; Azimmohseni, Majid

    2016-11-01

    Tree seed dormancy release by cold stratification accompanies with the embryo increased gluconeogenesis competence. Cyanide also breaks seed dormancy however, integrated information about its effects on carbon metabolism is lacking. Accordingly, the impacts of HCN on germination, lipid gluconeogenesis and sugar transport capacity of walnut (Juglans regia L.) kernels were investigated during 10-days period prior to radicle protrusion. HCN increased walnut kernel germination and within four days of kernel incubation, hastened the decline of starch, reducing and non-reducing sugars and led to greater activities of alkaline invertase and glucose-6-phosphate dehydrogenase. From four days of kernel incubation onwards, starch and non-reducing sugars accumulated only in the HCN treated axes. Cyanide also increased the activities of phosphoenolpyruvate carboxykinase and glyoxysomal succinate oxidase and led to greater acid invertase activity during the aforementioned period. The expressions of both sucrose transporter (JrSUT1) and H + -ATPase (JrAHA1) genes especially in cotyledons and H + -ATPase activity in kernels were significantly enhanced by exposure to cyanide. Thus in short-term HCN led to prevalence of carbohydrate catabolic events such as oxidative pentose phosphate pathway and possibly glycolysis in dormant walnut kernels. Long-term effects however, are increased gluconeogenesis and enhanced sugar transport capacity of kernels as a prerequisite for germination. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  19. Emissions from Forest Fires near Mexico City

    NASA Technical Reports Server (NTRS)

    Yokelson, R.; Urbanski, S.; Atlas, E.; Toohey, D.; Alvarado, E.; Crounse, J.; Wennberg, P.; Fisher, M.; Wold, C.; Campos, T.; hide

    2007-01-01

    The emissions of NOx (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 NOX to volatile organic compounds (VOC) for these MC-area mountain fires was approximately 0.38, which is similar to the NOx/VOC ratio in the MC urban area emissions inventory of 0.34, but much larger than the NOx/VOC ratio for tropical forest fires in Brazil (approximately 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 MCarea (approximately 98-100 W and 19-20 N). Comparing the PM10/CO and PM2.5/CO mass ratios in the MC Metropolitan Area emission inventory (0.01 15 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 approximately 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.

  20. Occupational exposure to hydrogen cyanide during large-scale cassava processing, in Alagoas State, Brazil.

    PubMed

    Zacarias, Cyro Hauaji; Esteban, Claudia; Rodrigues, Gilson Lucio; Nascimento, Elizabeth de Souza

    2017-07-27

    The cassava roots used for flour production contain high amounts of cyanogenic glycosides and are, therefore, potential hydrogen cyanide (HCN) releasers. This fact is the cause of an increasing health concern in the sector of cassava processing. Brazilian workers engaged in the flour production may be chronically exposed to HCN in levels above the safety limits. This hypothesis is based on the drastic reduction in cyanide content of cassava roots during a traditional Brazilian method of processing and in the physical properties of the compound, which makes it very susceptible to volatilization and air contamination. As an attempt to explore this issue, HCN exposure in Brazilian "flour houses" was evaluated in this study through environmental and biological monitoring. Four flour houses placed in Alagoas State, Brazil, were investigated. The results indicated that the cassava processors are chronically exposed to HCN at average levels between 0.464 and 3.328mg/m3 (TWA), in the work environment. This range is below the TLV-C of 5mg/m3 but not below the Action Level of 2.5mg/m3. These data may be interpreted as a possible risk to susceptible individuals. Additionally, the biological monitoring indicated a high cyanide exposure in the population study, considering urinary thiocyanate (SCN-) levels.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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.

  3. Exploring the volatile composition of comets C/2012 F6 (Lemmon) and C/2012 S1 (ISON) with ALMA

    NASA Astrophysics Data System (ADS)

    Bøgelund, Eva G.; Hogerheijde, Michiel R.

    2017-08-01

    Context. Comets formed in the outer and cold parts of the disk which eventually evolved into our solar system. Assuming that the comets have undergone no major processing, studying their composition provides insight in the pristine composition of the Solar Nebula. Aims: We derive production rates for a number of volatile coma species and explore how molecular line ratios can help constrain the uncertainties of these rates. Methods: We analyse observations obtained with the Atacama Large Millimeter/Submillimeter Array of the volatile composition of the comae of comets C/2012 F6 (Lemmon) and C/2012 S1 (ISON) at heliocentric distances of 1.45 AU and 0.56 AU, respectively. Assuming a Haser profile with constant outflow velocity, we model the line intensity of each transition using a 3D radiative transfer code and derive molecular production rates and parent scale lengths. Results: We report the first detection of CS in comet ISON obtained with the ALMA array and derive a parent scale length for CS of 200 km. Due to the high spatial resolution of ALMA, resulting in a synthesised beam with a size slightly smaller than the derived parent scale length (0.̋59 × 0.̋39 corresponding to (375 × 250) km at the distance of the comet at the time of observations), we are able to tentatively identify CS as a daughter species, I.e., a species produced in the coma and/or sublimated from icy grains, rather than a parent species. In addition we report the detection of several CH3OH transitions and confirm the previously reported detections of HCN, HNC and H2CO as well as dust in the coma of each comet, and report 3σ upper limits for HCO+. Conclusions: We derive molecular production rates relative to water of 0.2% for CS, 0.06-0.1% for HCN, 0.003-0.05% for HNC, 0.1-0.2% for H2CO and 0.5-1.0% for CH3OH, and show that the modelling uncertainties due to unknown collision rates and kinematic temperatures are modest and can be mitigated by available observations of different transitions

  4. Hyperswitch Communication Network Computer

    NASA Technical Reports Server (NTRS)

    Peterson, John C.; Chow, Edward T.; Priel, Moshe; Upchurch, Edwin T.

    1993-01-01

    Hyperswitch Communications Network (HCN) computer is prototype multiple-processor computer being developed. Incorporates improved version of hyperswitch communication network described in "Hyperswitch Network For Hypercube Computer" (NPO-16905). Designed to support high-level software and expansion of itself. HCN computer is message-passing, multiple-instruction/multiple-data computer offering significant advantages over older single-processor and bus-based multiple-processor computers, with respect to price/performance ratio, reliability, availability, and manufacturing. Design of HCN operating-system software provides flexible computing environment accommodating both parallel and distributed processing. Also achieves balance among following competing factors; performance in processing and communications, ease of use, and tolerance of (and recovery from) faults.

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

    NASA Technical Reports Server (NTRS)

    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.; hide

    2009-01-01

    We investigate the spatial and temporal distribution of hydrogen cyanide (HCN) in the upper troposphere through numerical simulations and comparison with observations from a space-based instrument. To perform the simulations, we used the Global Environmental Multiscale Air Quality model (GEM-AQ), which is based on the threedimensional Gobal multiscale model developed by the Meteorological Service of Canada for operational weather forecasting. The model was run for the period 2004-2006 on a 1.5deg x 1.5deg global grid with 28 hybrid vertical levels from the surface up to 10 hPa. Objective analysis data from the Canadian Meteorological Centre were used to update the meteorological fields every 24 h. Fire emission fluxes of gas species were generated by using year-specific inventories of carbon emissions with 8-day temporal resolution from the Global Fire Emission Database (GFED) version 2. The model output is compared with HCN profiles measured by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) instrument onboard the Canadian SCISAT-1 satellite. High values of up to a few ppbv are observed in the tropics in the Southern Hemisphere; the enhancement in HCN volume mixing ratios in the upper troposphere is most prominent in October. Low upper-tropospheric mixing ratios of less than 100 pptv are mostly recorded at middle and high latitudes in the Southern Hemisphere in May-July. Mixing ratios in Northern Hemisphere peak in the boreal summer. The amplitude of the seasonal variation is less pronounced than in the Southern Hemisphere. The comparison with the satellite data shows that in the upper troposphere GEM-AQ perform7s well globally for all seasons, except at northern hi gh and middle latitudes in surnmer, where the model has a large negative bias, and in the tropics in winter and spring, where it exhibits large positive bias. This may reflect inaccurate emissions or possible inaccuracies in the emission profile. The model is able to

  6. Mechanism of H2 histamine receptor dependent modulation of body temperature and neuronal activity in the medial preoptic nucleus

    PubMed Central

    Tabarean, Iustin V.; Sanchez-Alavez, Manuel; Sethi, Jasmine

    2012-01-01

    Histamine is involved in the central control of arousal, circadian rhythms and metabolism. The preoptic area, a region that contains thermoregulatory neurons is the main locus of histamine modulation of body temperature. Here we report that in mice histamine activates H2 subtype receptors in the medial preoptic nucleus (MPON) and induces hyperthermia. We also found that a population of glutamatergic MPON neurons express H2 receptors and are excited by histamine or H2 specific agonists. The agonists decreased the input resistance of the neuron and increased the depolarizing “sag” observed during hyperpolarizing current injections. Furthermore, at −60 mV holding potential activation of H2 receptors induced an inward current that was blocked by ZD7288, a specific blocker of the hyperpolarization activated cationic current (Ih). Indeed, activation of H2 receptors resulted in increased Ih amplitude in response to hyperpolarizing voltage steps and a depolarizing shift in its voltage-dependent activation. The neurons excited by H2 specific agonism expressed the HCN1 and HCN2 channel subunits. Our data indicate that at the level of the MPON histamine influences thermoregulation by increasing the firing rate of glutamatergic neurons that express H2 receptors. PMID:22366077

  7. The nature of the dense obscuring material in the nucleus of NGC 1068

    NASA Technical Reports Server (NTRS)

    Tacconi, L. J.; Genzel, R.; Blietz, M.; Cameron, M.; Harris, A. I.; Madden, S.

    1994-01-01

    High spatial and spectral resolution observations of the distribution, physical parameters, and kinematics of the molecular interstellar medium toward the nucleus of the Seyfert 2 galaxy NGC 1068 are reported. The data consist of 2.4 by 3.4 arcseconds resolution interferometry of the 88.6 GHz HCN J = 1 towards 0 line at 17 km/s spectral resolution, single dish observations of several mm/submm isotopic lines of CO and HCN, and 0.85 arcseconds imaging spectroscopy of the 2.12 micron H2 S(1) line at a velocity resolution of 110 km/s. The central few hundred parsecs of NGC 1068 contain a system of dense (N(H2) approximately 10(exp 5) cm(exp -3)), warm (T greater than or equal to 70 K) molecular cloud cores. The low density molecular envelopes have probably been stripped by the nuclear wind and radiation. The molecular gas layer is located in the plane of NGC 1068's large scale disk (inclination approximately 35 deg) and orbits in elliptical streamlines in response to the central stellar bar. The spatial distribution of the 2 micron H2 emission suggests that gas is shocked at the leading edge of the bar, probably resulting in gas influx into the central 100 pc at a rate of a few solar mass per year. In addition to large scale streaming (with a solid body rotation curve), the HCN velocity field requires the presence of random motions of order 100 km/s. We interpret these large random motions as implying the nuclear gas disk to be very thick (scale height/radius approximately 1), probably as the result of the impact of nuclear radiation and wind on orbiting molecular clouds. Geometry and column density of the molecular cloud layer between approximately 30 pc to 300 pc from the nucleus can plausibly account for the nuclear obscuration and anisotropy of the radiation field in the visible and UV.

  8. Decomposition Characteristics of Acetone in a DC Corona Discharge at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Sakamoto, Takahiro; Satoh, Kohki; Itoh, Hidenori

    Decomposition characteristics of acetone in a DC corona discharge generated between a multi-needle and a plane electrodes in nitrogen-oxygen mixtures at atmospheric pressure are investigated mainly by infrared absorption spectroscopy in this work. It is found that CO2, CO, CH4, HCHO, HCOOH and HCN are the by-products of acetone in the corona discharge, and that CO, CH4, HCHO, HCOOH and HCN are intermediate products, which tend to be decomposed in the corona discharge. CO2 is found to be the major and end-product. It is also found that acetone is chiefly inverted to CO2 via CO at high oxygen concentration (20%) and via CO and CH4 at relatively low oxygen concentration (0.2%), in addition to the direct conversion from acetone to CO2. As the oxygen concentration increases, the percentages of carbon atoms contained in deposit on the plane electrode and the wall of the discharge chamber increases. Further, the decomposition process of acetone is deduced from the examination of rate constants for the reactions in the gaseous phase.

  9. Thermal wet decomposition of Prussian Blue: implications for prebiotic chemistry.

    PubMed

    Ruiz-Bermejo, Marta; Rogero, Celia; Menor-Salván, César; Osuna-Esteban, Susana; Martín-Gago, José Angel; Veintemillas-Verdaguer, Sabino

    2009-09-01

    The complex salt named Prussian Blue, Fe4[Fe(CN)6]3 x 15 H2O, can release cyanide at pH > 10. From the point of view of the origin of life, this fact is of interest, since the oligomers of HCN, formed in the presence of ammonium or amines, leads to a variety of biomolecules. In this work, for the first time, the thermal wet decomposition of Prussian Blue was studied. To establish the influence of temperature and reaction time on the ability of Prussian Blue to release cyanide and to subsequently generate other compounds, suspensions of Prussian Blue were heated at temperatures from room temperature to 150 degrees at pH 12 in NH3 environment for several days. The NH3 wet decomposition of Prussian Blue generated hematite, alpha-Fe2O3, the soluble complex salt (NH4)4[Fe(CN6)] x 1.5 H2O, and several organic compounds, the nature and yield of which depend on the experimental conditions. Urea, lactic acid, 5,5-dimethylhydantoin, and several amino acids and carboxylic acids were identified by their trimethylsilyl (TMS) derivatives. HCN, cyanogen (C2N2), and formamide (HCONH2) were detected in the gas phase by GC/MS analysis.

  10. 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

    NASA Astrophysics Data System (ADS)

    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).

  11. Long-term outcomes of pediatric sinus bradycardia.

    PubMed

    Chiu, Shuenn-Nan; Lin, Lian-Yu; Wang, Jou-Kou; Lu, Chun-Wei; Chang, Chi-Wei; Lin, Ming-Tai; Hua, Yu Chuan; Lue, Hung-Chi; Wu, Mei-Hwan

    2013-09-01

    To delineate the long-term outcomes and mechanisms of pediatric sinus bradycardia. Participants with sinus bradycardia who were identified from a survey of 432,166 elementary and high school students, were enrolled 10 years after the survey. The clinical course, heart rate variability, and hyperpolarization-activated cyclic nucleotide-gated potassium channel 4 (HCN4) gene were assessed. A total of 104 (male:female was 60:44; prevalence, 0.025%) participants were observed to have sinus bradycardia at age 15.5 ± 0.2 years with a mean heart rate of 48.4 ± 0.4 beats per minute; 86 study participants (83%) responded to clinical assessment and 37 (36%) underwent laboratory assessment. Athletes composed 37.8% of the study participants. During the extended 10-year follow-up, 15 (17%) of the participants had self-limited syncopal episodes, but none had experienced life-threatening events. According to Holter recordings, none of the participants had heart rate <30 beats per minute or a pause longer than 3 seconds. Compared with 67 age- and sex-matched controls, the variables of heart rate based on the spectral and time domain analysis of the participants with sinus bradycardia were all significantly higher, indicating higher parasympathetic activity. The results of mutation analysis were negative in the HCN4 gene in all of our participants. The long-term outcomes of the children and adolescents with sinus bradycardia identified using school electrocardiographic survey are favorable. Parasympathetic hyperactivity, instead of HCN4 gene mutation, is responsible for the occurrence of sinus bradycardia. Copyright © 2013 Mosby, Inc. All rights reserved.

  12. Fate in humans of dietary intake of cyanogenic glycosides from roots of sweet cassava consumed in Cuba.

    PubMed

    Hernández, T; Lundquist, P; Oliveira, L; Pérez Cristiá, R; Rodriguez, E; Rosling, H

    1995-01-01

    We studied if consumption of boiled fresh roots from sweet cassava varieties grown in Cuba resulted in exposure to cyanogenic glycosides and their final breakdown product, cyanide. When adult, nonsmoking subjects consumed 1-4 kg cassava over 2 days, their urinary levels of the main cyanide metabolite, thiocyanate, only increased from a mean +/- SEM of 12 +/- 2 to 22 +/- 2 mumol/l, indicating a negligible cyanide exposure. Their mean urinary linamarin, the main cyanogenic glucoside in cassava, increased from 2 +/- 1 to 68 +/- 16 mumol/l. In a second experiment 5 subjects consumed one meal of 0.5 kg boiled cassava that contained 105 mumol linamarin and 8 mumol hydrogen cyanide (HCN). Quantitative urine collections prior to and after intake showed that 28% of linamarin was excreted during the following 24 hours, whereas a modest increase of urinary thiocyanate (SCN) only corresponded to the small amount of free HCN ingested. These results indicate that the dominant cyanogen in boiled cassava is glycosides that pass through the human body without causing cyanide exposure. It remains to be studied whether humans occasionally possess intestinal or tissue beta-glucosidases that can hydrolyse cyanogenic glycosides from cassava.

  13. Research and Development in support of the Surface Chemistry Branch. Volume 1

    DTIC Science & Technology

    1988-06-01

    reactions could occur in the melt and/or gas phase-and (2) formation of HCN from RDX pyrolysis followed by hydrolysis with atmospheric/RDX decomposition ...interest is the development of electrochemically active transition metal complexes for the catalytic conversion/ decomposition of dissolved gases, such...impregnated charcoals for the collection and catalytic decomposition of toxic vapors (2), and the evaluation of Navy shipboard environments (3). For the

  14. Toward Gas Chemistry in Low Metallicity Starburst Galaxies

    NASA Astrophysics Data System (ADS)

    Meier, David S.; Anderson, Crystal N.; Turner, Jean; Ott, Juergen; Beck, Sara C.

    2017-01-01

    Dense gas, which is intimately connected with star formation, is key to understanding star formation. Though challenging to study, dense gas in low metallicity starbursts is important given these system's often extreme star formation and their potential implications for high redshift analogs. High spatial resolution (~50 pc) ALMA observations of several key probes of gas chemistry, including HCN(1-0), HCO+(1-0), CS(2-1), CCH(1-0;3/2-1/2) and SiO(2-1), towards the nearby super star-cluster (SSC) forming, sub-solar metallicity galaxy NGC 5253 are discussed. Dense gas is observed to be extended well beyond the current compact starburst, reaching into the apparently infalling molecular streamer. The faintness of HCN, the standard dense gas tracer, is extreme both in an absolute sense relative to high metallicity starbursts of a similar intensity and in a relative sense, with the HCO+/HCN ratio being one of the most elevated observed. UV-irradiated molecular gas, traced by CCH, is also extended over the mapped region, not being strongly correlated with the SSC. Despite the accretion of molecular gas from the halo and the intense burst of star formation, chemical signatures of shocked gas, traced by SiO (and HNCO), are not obvious. By placing NGC 5253 in context with other local starbursts, like 30 Doradus in the Large Magellanic Clouds and the high metallicity proto-typical starburst NGC 253, it is suggested that a combination of gas excitation and abundance changes associated with the sub solar metallicity may explain these anomalous dense gas properties.

  15. Health Council of The Netherlands: no need to change from SAR to time-temperature relation in electromagnetic fields exposure limits.

    PubMed

    van Rhoon, Gerard C; Aleman, André; Kelfkens, Gert; Kromhout, Hans; Van Leeuwen, Flora E; Savelkoul, Huub F J; Wadman, Wytse J; Van De Weerdt, Rik D H J; Zwamborn, A Peter M; Van Rongen, Eric

    2011-01-01

    The Health Council of the Netherlands (HCN) and other organisations hold the basic assumption that induced electric current and the generation and absorption of heat in biological material caused by radiofrequency electromagnetic fields are the only causal effects with possible adverse consequences for human health that have been scientifically established to date. Hence, the exposure guidelines for the 10 MHz-10 GHz frequency range are based on avoiding adverse effects of increased temperatures that may occur of the entire human body at a specific absorption rate (SAR) level above 4 W/kg. During the workshop on Thermal Aspects of Radio Frequency Exposure on 11-12 January 2010 in Gaithersburg, Maryland, USA, the question was raised whether there would be a practical advantage in shifting from expressing the exposure limits in SAR to expressing them in terms of a maximum allowable temperature increase. This would mean defining adverse time-temperature thresholds. In this paper, the HCN discusses the need for this, considering six points: consistency, applicability, quantification, causality, comprehensibility and acceptability. The HCN concludes that it seems unlikely that a change of dosimetric quantity will help us forward in the discussion on the scientific controversies regarding the existence or non-existence of non-thermal effects in humans following long duration, low intensity exposure to electromagnetic fields. Therefore, the HCN favours maintaining the current approach of basic restrictions and reference levels being expressed as SAR and in V/m or µT, respectively.

  16. Rotation-stimulated structures in the CN and C3 comae of comet 103P/Hartley 2 close to the EPOXI encounter

    NASA Astrophysics Data System (ADS)

    Waniak, W.; Borisov, G.; Drahus, M.; Bonev, T.

    2012-07-01

    Context. In late 2010, a Jupiter family comet 103P/Hartley 2 was the subject of an intensive world-wide investigation. On UT October 20.7, the comet approached the Earth within only 0.12 AU, and on UT November 4.6 it was visited by the NASA EPOXI spacecraft. Aims: We joined this international effort and organized a ground-based observing campaign with three key goals to: (1) measure the parameters of the nucleus rotation in a time series of CN; (2) investigate the compositional structure of the coma by comparing the CN images with nightly snapshots of C3; and (3) investigate the photochemical relation of CN to HCN, using the HCN data collected nearly simultaneously with our images. Methods: The images were obtained through narrowband filters using the two-meter telescope of the Rozhen National Astronomical Observatory. They were taken over four nights about the moment of the EPOXI encounter. Image processing methods and periodicity analysis techniques were used to identify transient coma structures and investigate their repeatability and kinematics. Results: We observe shells, arc-, jet- and spiral-like patterns that are very similar for the CN and C3 comae. The CN features expanded outwards with the sky-plane projected velocities of between 0.1 to 0.3 km s-1. A corkscrew structure, observed on November 6, evolved with a much higher velocity of 0.66 km s-1. The photometry of the inner coma of CN shows variability with a period of 18.32 ± 0.30 h (valid for the middle moment of our run, UT 2010 Nov 5.0835), which we attribute to the nucleus rotation. This result is fully consistent with independent determinations around the same time by other teams. The pattern of repeatability is, however, imperfect, which is understendable given the suggested excitation of the rotation state, and the variability detected in CN correlates well with the cyclic changes in HCN, but only in the active phases. The identified coma structures, along with the snapshot of the nucleus

  17. Altered Left Ventricular Ion Channel Transcriptome in a High-Fat-Fed Rat Model of Obesity: Insight into Obesity-Induced Arrhythmogenesis

    PubMed Central

    Yon, Marianne; Pickavance, Lucy; Yanni Gerges, Joseph; Davis, Gershan; Wilding, John; Jian, Kun; Hart, George; Boyett, Mark

    2016-01-01

    Introduction. Obesity is increasingly common and is associated with an increased prevalence of cardiac arrhythmias. The aim of this study was to see whether in obesity there is proarrhythmic gene expression of ventricular ion channels and related molecules. Methods and Results. Rats were fed on a high-fat diet and compared to control rats on a normal diet (n = 8). After 8 weeks, rats on the high-fat diet showed significantly greater weight gain and higher adiposity. Left ventricle samples were removed at 8 weeks and mRNA expression of ion channels and other molecules was measured using qPCR. Obese rats had significant upregulation of Cav1.2, HCN4, Kir2.1, RYR2, NCX1, SERCA2a, and RYR2 mRNA and downregulation of ERG mRNA. In the case of HCN4, it was confirmed that there was a significant increase in protein expression. The potential effects of the mRNA changes on the ventricular action potential and intracellular Ca2+ transient were predicted using computer modelling. Modelling predicted prolongation of the ventricular action potential and an increase in the intracellular Ca2+ transient, both of which would be expected to be arrhythmogenic. Conclusion. High-fat diet causing obesity results in arrhythmogenic cardiac gene expression of ion channels and related molecules. PMID:27747100

  18. 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

    PubMed Central

    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

  19. Expression of MdCAS1 and MdCAS2, encoding apple beta-cyanoalanine synthase homologs, is concomitantly induced during ripening and implicates MdCASs in the possible role of the cyanide detoxification in Fuji apple (Malus domestica Borkh.) fruits.

    PubMed

    Han, Sang Eun; Seo, Young Sam; Kim, Daeil; Sung, Soon-Kee; Kim, Woo Taek

    2007-08-01

    Fruit ripening involves complex biochemical and physiological changes. Ethylene is an essential hormone for the ripening of climacteric fruits. In the process of ethylene biosynthesis, cyanide (HCN), an extremely toxic compound, is produced as a co-product. Thus, most cyanide produced during fruit ripening should be detoxified rapidly by fruit cells. In higher plants, the key enzyme involved in the detoxification of HCN is beta-cyanoalanine synthase (beta-CAS). As little is known about the molecular function of beta-CAS genes in climacteric fruits, we identified two homologous genes, MdCAS1 and MdCAS2, encoding Fuji apple beta-CAS homologs. The structural features of the predicted polypeptides as well as an in vitro enzyme activity assay with bacterially expressed recombinant proteins indicated that MdCAS1 and MdCAS2 may indeed function as beta-CAS isozymes in apple fruits. RNA gel-blot studies revealed that both MdCAS1 and MdCAS2 mRNAs were coordinately induced during the ripening process of apple fruits in an expression pattern comparable with that of ACC oxidase and ethylene production. The MdCAS genes were also activated effectively by exogenous ethylene treatment and mechanical wounding. Thus, it seems like that, in ripening apple fruits, expression of MdCAS1 and MdCAS2 genes is intimately correlated with a climacteric ethylene production and ACC oxidase activity. In addition, beta-CAS enzyme activity was also enhanced as the fruit ripened, although this increase was not as dramatic as the mRNA induction pattern. Overall, these results suggest that MdCAS may play a role in cyanide detoxification in ripening apple fruits.

  20. The Properties and Effects of Titan's Organic Haze

    NASA Technical Reports Server (NTRS)

    McKay, Christopher P.; Young, Richard E. (Technical Monitor)

    1997-01-01

    Titan's organic haze is the the dominant absorber of solar energy in Titan's atmosphere, creating an anti-greenhouse effect. Its variation over time may have had important implications for Titan's surface temperature. The haze is potentially an important sink of photochemically produced carbon and nitrogen compounds. Laboratory simulations and microphysical models suggest that the haze is a sink for C of 4 x 10(exp 8)/ sq cm s, and a sink for N of 1 x 10(exp 8)sq cm s. The C sink is small compared to condensation of hydrocarbons but the sink for N is comparable to the total production rate of HCN. Because estimates of the eddy diffusion profile on Titan have been based on the HCN profile, inclusion of this additional sink for N will affect estimates for all transport processes in Titan's atmosphere.

  1. 40 CFR 63.8800 - What performance tests and other procedures must I use to demonstrate compliance with the...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Emission Standards for Hazardous Air Pollutants: Flexible Polyurethane Foam Fabrication Operations Testing... paragraphs (e)(1) through (3) of this section. (1) If you use chlorinated fire retardant foams, determine the... retardant foams, determine the percent reduction of HCN to represent HAP emissions from the source. (2...

  2. 40 CFR 63.8800 - What performance tests and other procedures must I use to demonstrate compliance with the...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Emission Standards for Hazardous Air Pollutants: Flexible Polyurethane Foam Fabrication Operations Testing... paragraphs (e)(1) through (3) of this section. (1) If you use chlorinated fire retardant foams, determine the... retardant foams, determine the percent reduction of HCN to represent HAP emissions from the source. (2...

  3. 40 CFR 63.8800 - What performance tests and other procedures must I use to demonstrate compliance with the...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Emission Standards for Hazardous Air Pollutants: Flexible Polyurethane Foam Fabrication Operations Testing... paragraphs (e)(1) through (3) of this section. (1) If you use chlorinated fire retardant foams, determine the... retardant foams, determine the percent reduction of HCN to represent HAP emissions from the source. (2...

  4. 40 CFR 63.8800 - What performance tests and other procedures must I use to demonstrate compliance with the...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Emission Standards for Hazardous Air Pollutants: Flexible Polyurethane Foam Fabrication Operations Testing... paragraphs (e)(1) through (3) of this section. (1) If you use chlorinated fire retardant foams, determine the... retardant foams, determine the percent reduction of HCN to represent HAP emissions from the source. (2...

  5. 40 CFR 63.8800 - What performance tests and other procedures must I use to demonstrate compliance with the...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Emission Standards for Hazardous Air Pollutants: Flexible Polyurethane Foam Fabrication Operations Testing... paragraphs (e)(1) through (3) of this section. (1) If you use chlorinated fire retardant foams, determine the... retardant foams, determine the percent reduction of HCN to represent HAP emissions from the source. (2...

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Espada, D.; Miura, R. E.; Iono, D.

    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 leadingmore » 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.« less

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

    NASA Technical Reports Server (NTRS)

    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.; hide

    2012-01-01

    Comets retain relatively primitive icy material remaining from the epoch of Solar System for111ation, 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 3-5 micrometer region. With modern instrumentation on worldclass 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.

  8. A new channel for the formation of hydrogen cyanide in CH2-N2 systems

    NASA Technical Reports Server (NTRS)

    Laufer, A. H.; Bass, A. M.

    1978-01-01

    The reaction between N2 and either the singlet or the triplet electronic state of CH2 is investigated in order to shed light on the formation of NO in fuel-rich hydrocarbon flames. For the reaction of N2 and the triplet CH2, a rate constant less than or equal to 10 to the minus 16th power cu cm/molecule-sec is obtained. The time history of hydrogen cyanide production from the CH2-N2 systems is discussed as a basis for understanding the possible reaction routes from HCN to NO.

  9. Simulation and optical spectroscopy of a DC discharge in a CH4/H2/N2 mixture during deposition of nanostructured carbon films

    NASA Astrophysics Data System (ADS)

    Mironovich, K. V.; Mankelevich, Yu. A.; Voloshin, D. G.; Dagesyan, S. A.; Krivchenko, V. A.

    2017-08-01

    Two-dimensional numerical simulations of a dc discharge in a CH4/H2/N2 mixture in the regime of deposition of nanostructured carbon films are carried out with account of the cathode electron beam effects. The distributions of the gas temperature and species number densities are calculated, and the main plasmachemical kinetic processes governing the distribution of methyl radicals above the substrate are analyzed. It is shown that the number density of methyl radicals above the substrate is several orders of magnitude higher than the number densities of other hydrocarbon radicals, which indicates that the former play a dominant role in the growth of nanostructured carbon films. The model is verified by comparing the measured optical emission profiles of the H( n ≡ 3), C 2 * , CH*, and CN* species and the calculated number densities of excited species, as well as the measured and calculated values of the discharge voltage and heat fluxes onto the electrodes and reactor walls. The key role of ion-electron recombination and dissociative excitation of H2, C2H2, CH4, and HCN molecules in the generation of emitting species (first of all, in the cold regions adjacent to the electrodes) is revealed.

  10. ALMA observations of Titan : Vertical and spatial distribution of nitriles

    NASA Astrophysics Data System (ADS)

    Moreno, R.; Lellouch, E.; Vinatier, S.; Gurwell, M.; Moullet, A.; Lara, L. M.; Hidayat, T.

    2015-10-01

    We report submm observations of Titan performed with the ALMA interferometer centered at the rotational frequencies of HCN(4-3) and HNC(4-3), i.e. 354 and 362 GHz. These measurements yielded disk-resolved emission spectra of Titan with an angular resolution of ~0.47''. Titan's angular surface diameter was 0.77''. Data were acquired in summer 2012 near the greatest eastern and western elongations of Titan at a spectral resolution of 122 kHz (λ/d λ = 3106). We have obtained maps of several nitriles present in Titan' stratosphere: HCN, HC3N, CH3CN, HNC, C2H5CNand other weak lines (isotopes, vibrationnally excited lines).We will present radiative transfer analysis of the spectra acquired. With the combination of all these detected rotational lines, we will constrain the atmospheric temperature, the spatial and vertical distribution of these species, as well as isotopic ratios. Moreover, Doppler lineshift measurements will enable us to constrain the zonal wind flow in the upper atmosphere.

  11. Nonequilibrium chemistry in shocked molecular clouds. [interstellar gases

    NASA Technical Reports Server (NTRS)

    Iglesias, E. R.; Silk, J.

    1978-01-01

    The gas-phase chemistry is studied behind a 10-km/s shock propagating into a dense molecular cloud. The principal conclusions are that: the concentrations of certain molecules (CO, NH3, HCN, N2) are unperturbed by the shock; other molecules (H2CO, CN, HCO(+)) are greatly decreased in abundance; and substantial amounts of H2O, HCO, and CH4 are produced. Approximately 1 million yr (independent of the density) must elapse after shock passage before chemical equilibrium is attained.

  12. Effects of ZD7288 on firing pattern of thermosensitive neurons isolated from hypothalamus.

    PubMed

    Cai, Chunqing; Meng, Xiaojing; He, Junchu; Wu, Hangyu; Zou, Fei

    2012-01-11

    The role of the hyperpolarization-activated current (Ih) mediated by HCN channels in temperature sensing by the hypothalamus was addressed. In warm-sensitive neurons (WSNs), exposure to ZD7288, an inhibitor of Ih mediated by hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, decreased their action potential amplitudes and frequencies significantly. By contrast, ZD7288 had little or no effect on temperature-insensitive neurons (TINs). Exposure of WSNs to ZD7288 led to a significant increase in the duration of the inter-spike interval and a reduction of Ih irreversibly. These results suggest that ZD7288 have the contrasting effects on the firing patterns of WSNs versus TINs, which implies HCN channels play a central role in temperature sensing by hypothalamic neurons. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  13. Kinetic and mechanisms of methanimine reactions with singlet and triplet molecular oxygen: Substituent and catalyst effects

    NASA Astrophysics Data System (ADS)

    Asgharzadeh, Somaie; Vahedpour, Morteza

    2018-06-01

    Methanimine reaction with O2 on singlet and triplet potential energy surfaces are investigated using B3PW91, M06-2X, MP2 and CCSD(T) methods. Thermodynamic and kinetic parameters are calculated at M06-2X method. The most favorable channel involves H-abstraction of CH2NH+O2 to the formation of HCN + H2O2 products via low level energy barrier. The catalytic effect of water molecule on HCN + H2O2 products pathway are investigated. Result shows that contribution of water molecule using complex formation with methanimine can decreases barrier energy of transition state and the reaction rate increases. Also, substituent effect of fluorine atom as deactivating group are investigated on the main reaction pathway.

  14. Pre- and Post-perihelion Observations of C/2009 P1 (Garradd): Evidence for an Oxygen-rich Heritage?

    NASA Technical Reports Server (NTRS)

    Disanti, Michael Antonio; Villanueva, Geronimo Luis; Paganini, Lucas; Bonev, Boncho P.; Keane, Jacqueline V.; Meech, Karen J.; Mumma, Michael Jon

    2013-01-01

    We conducted pre- and post-perihelion observations of Comet C/2009 P1 (Garradd) on UT 2011 October 13 and 2012 January 8, at heliocentric distances of 1.83 and 1.57 AU, respectively, using the high-resolution infrared spectrometer (NIRSPEC) at the Keck II 10-m telescope on Mauna Kea, HI. Pre-perihelion, we obtained production rates for nine primary volatiles (native ices): H2O, CO, CH3OH, CH4, C2H6, HCN, C2H2, H2CO, and NH3. Post-perihelion, we obtained production rates for three of these (H2O, CH4, and HCN) and sensitive upper limits for three others (C2H2, H2CO, and NH3). CO was enriched and C2H2 was depleted, yet C2H6 and CH3OH were close to their currentmean values asmeasured in a dominant group of Oort cloud comets. This may indicate processing of its pre-cometary ices in a relatively oxygen-rich environment. Our measurements indicate consistent pre- and post-perihelion abundance ratios relative to H2O, suggesting we were measuring compositional homogeneity among measured species to the depths in the nucleus sampled. However, the overall gas production was lower post-perihelion despite its smaller heliocentric distance on January 8. This is qualitatively consistent with other studies of C/2009 P1, perhaps due to seasonal differences in the heating of one or more active regions on the nucleus. On October 13, the water profile showed a pronounced excess towards the Sun-facing hemisphere that was not seen in other molecules, including H2O on January 8, nor in the dust continuum. Inter-comparison of profiles from October 13 permitted us to quantify contributions due to release of H2O from the nucleus, and fromits release in the coma. This resulted in the latter source contributing 25-30% of the total observed water within our slit, which covered roughly +/-300 km by +/-4500 km from the nucleus. We attribute this excess H2O, which peaked at a mean projected distance of 1300-1500 km from the nucleus, to release from water-rich, relatively pure icy grains

  15. Cyanide, Peroxide and Nitric Oxide Formation in Solutions of Hydroxyurea Causes Cellular Toxicity and May Contribute to its Therapeutic Potency

    PubMed Central

    Kuong, Kawai J.; Kuzminov, Andrei

    2009-01-01

    Hydroxyurea is a potent remedy against a variety of ailments and an efficient inhibitor of DNA synthesis, yet its pharmacology is unclear. Hydroxyurea acts in Escherichia coli by the same mechanism as it does in eukaryotes, via inhibition of ribonucleotide reductase. When examining a controversy about concentrations of hydroxyurea that prevent thymineless death in E. coli, we found instability in hydroxyurea solutions which avoided prior detection due to its peculiar nature. In contrast to freshly dissolved hydroxyurea, which did not affect respiration and was bacteriostatic, one-day-old hydroxyurea solutions inhibited respiration and were immediately bactericidal. Respiration was inhibited by two gasses, hydrogen cyanide (HCN) and nitric oxide (NO), whose appearance we detected in “aged” hydroxyurea stocks by GC-MS; however, neither gas was bactericidal. While determining the cause of toxicity, we found that hydroxyurea damages DNA directly. We also demonstrated accumulation of peroxides in hydroxyurea solutions by enzymatic assays, which explains the toxicity, as both NO and HCN are known to kill bacteria when combined with hydrogen peroxide. Remarkably, we found that bactericidal effects of NO + H2O2 and HCN + H2O2 mixtures were further synergistic. Accumulation of decomposition products in solutions of hydroxyurea may explain the broad therapeutic effects of this drug. PMID:19467244

  16. Recovery of cyanide in gold leach waste solution by volatilization and absorption.

    PubMed

    Gönen, N; Kabasakal, O S; Ozdil, G

    2004-09-10

    In this study, the effects of pH, time and temperature in regeneration of cyanide in the leaching waste solution of gold production from disseminated gold ore by cyanidation process were investigated and the optimum conditions, consumptions and cyanide recovery values were determined. The sample of waste solution containing 156 mg/l free CN- and 358 mg/l total CN-, that was obtained from Gümüşhane-Mastra/Turkey disseminated gold ores by cyanidation and carbon-in-pulp (CIP) process under laboratory conditions was used in the experiments. Acidification with H2SO4, volatilization of hydrogen cyanide (HCN) with air stripping and absorption of HCN in a basic solution stages were applied and under optimum conditions, 100% of free cyanide and 48% of complex cyanide and consequently 70% of the total cyanide in the liquid phase of gold leach effluent are recovered.

  17. The organic surface of 5145 Pholus: Constraints set by scattering theory

    NASA Technical Reports Server (NTRS)

    Wilson, Peter D.; Sagan, Carl; Thompson, W. Reid

    1994-01-01

    No known body in the Solar System has a spectrum redder than that of object 5145 Pholus. We use Hapke scattering theory and optical constants measured in this laboratory to examine the ability of mixtures of a number of organic solids and ices to reproduce the observed spectrum and phase variation. The primary materials considered are poly-HCN, kerogen, Murchison organic extract, Titan tholin, ice tholin, and water ice. In a computer grid search of over 10 million models, we find an intraparticle mixture of 15% Titan tholin, 10% poly-HCN, and 75% water ice with 10-micrometers particles to provide an excellent fit. Replacing water ice with ammonia ice improves the fits significantly while using a pure hydrocarbon tholin, Tholin alpha, instead of Titan tholin makes only modest improvements. All acceptable fits require Titan tholin or some comparable material to provide the steep slope in the visible, and poly-HCN or some comparable material to provide strong absorption in the near-infrared. A pure Titan tholin surface with 16-micrometers particles, as well as all acceptable Pholus models, fit the present spectrophotometric data for the transplutonian object 1992 QB(sub 1). The feasibility of gas-phase chemistry to generate material like Titan tholin on such small objects is examined. An irradiated transient atmosphere arising from sublimating ices may generate at most a few centimeters of tholin over the lifetime of the Solar System, but this is insignificant compared to the expected lag deposit of primordial contaminants left behind by the sublimating ice. Irradiation of subsurface N2/CH4 or NH3/CH4 ice by cosmic rays may generate approximately 20 cm of tholin in the upper 10 m of regolith in the same time scale but the identity of this tholin to its gas-phase equivalent has not been demonstrated.

  18. Modern spandrels: the roles of genetic drift, gene flow and natural selection in the evolution of parallel clines.

    PubMed

    Santangelo, James S; Johnson, Marc T J; Ness, Rob W

    2018-05-16

    Urban environments offer the opportunity to study the role of adaptive and non-adaptive evolutionary processes on an unprecedented scale. While the presence of parallel clines in heritable phenotypic traits is often considered strong evidence for the role of natural selection, non-adaptive evolutionary processes can also generate clines, and this may be more likely when traits have a non-additive genetic basis due to epistasis. In this paper, we use spatially explicit simulations modelled according to the cyanogenesis (hydrogen cyanide, HCN) polymorphism in white clover ( Trifolium repens ) to examine the formation of phenotypic clines along urbanization gradients under varying levels of drift, gene flow and selection. HCN results from an epistatic interaction between two Mendelian-inherited loci. Our results demonstrate that the genetic architecture of this trait makes natural populations susceptible to decreases in HCN frequencies via drift. Gradients in the strength of drift across a landscape resulted in phenotypic clines with lower frequencies of HCN in strongly drifting populations, giving the misleading appearance of deterministic adaptive changes in the phenotype. Studies of heritable phenotypic change in urban populations should generate null models of phenotypic evolution based on the genetic architecture underlying focal traits prior to invoking selection's role in generating adaptive differentiation. © 2018 The Author(s).

  19. The ExoMol pressure broadening diet: H2 and He line-broadening parameters

    NASA Astrophysics Data System (ADS)

    Barton, Emma J.; Hill, C.; Czurylo, M.; Li, H. Y.; Hyslop, A.; Yurchenko, Sergei N.; Tennyson, Jonathan

    2017-12-01

    In a variety of astronomical objects including gas giant (exo-)planets, brown dwarfs and cool stars, molecular hydrogen and helium are the major line broadeners. However, there is currently no systematic source for these parameters, particularly at the elevated temperatures encountered in many of these objects. The ExoMol project provides comprehensive molecular line lists for exoplanet and other hot atmospheres. The ExoMol database has recently been extended to provide additional data including temperature-dependent, pressure-broadening parameters. Here we assemble H2 and He pressure-broadening datasets for the molecules H2O, NH3, SO2, CH4, PH3, HCN and H2CO using available experimental and theoretical studies.

  20. Kinetics of hydrogen/deuterium exchanges in cometary ices

    NASA Astrophysics Data System (ADS)

    Faure, Mathilde; Quirico, Eric; Faure, Alexandre; Schmitt, Bernard; Theulé, Patrice; Marboeuf, Ulysse

    2015-11-01

    The D/H composition of volatile molecules composing cometary ices brings key constraints on the origin of comets, on the extent of their presolar heritage, as well as on the origin of atmospheres and hydrospheres of terrestrial planets. Nevertheless, the D/H composition may have been modified to various extents in the nucleus when a comet approaches the Sun and experiences deep physical and chemical modifications in its subsurface. We question here the evolution of the D/H ratio of organic species by proton exchanges with water ice. We experimentally studied the kinetics of D/H exchanges on the ice mixtures H2O:CD3OD, H2O:CD3ND2 and D2O:HCN. Our results show that fast exchanges occur on the -OH and -NH2 chemical groups, which are processed through hydrogen bonds exchanges with water and by the molecular mobility triggered by structural changes, such as glass transition or crystallization. D/H exchanges kinetic is best described by a second-order kinetic law with activation energies of 4300 ± 900 K and 3300 ± 100 K for H2O:CD3OD and H2O:CD3ND2 ice mixtures, respectively. The corresponding pre-exponential factors ln(A(s-1)) are 25 ± 7 and 20 ± 1, respectively. No exchange was observed in the case of HCN trapped in D2O ice. These results strongly suggest that upon thermal heating (1) -OH and -NH2 chemical groups of any organic molecules loose their primordial D/H composition and equilibrate with water ice, (2) HCN does not experience proton transfer and keeps a primordial D/H composition and (3) C-H chemical groups are not isotopically modified.

  1. Monitoring gas concentrations in environmental and atmospheric applications using tunable diode lasers

    NASA Astrophysics Data System (ADS)

    Awtry, Andrew R.

    Two atmospheric chemistry processes that contribute to environmental concerns have been explored using mid-infrared, lead-salt diode lasers. Tunable diode laser absorption spectroscopy was used to determine concentrations of both NF3 and NH3. The focus of the NF3 research was to determine the magnitude of the nu1 absorption band in order to determine the effects of this molecule on global warming. Deposition velocity is a proportionality constant between concentration and vertical flux to a surface. The magnitude of this constant for NH 3 depositing onto water is experimentally determined using both a small cell (425 mL) and a large chamber (335 L). The results from the chamber are then incorporated into a model in an attempt to better understand the atmospheric contribution to aqueous concentrations. Near-infrared diode lasers were used in both integrated cavity output spectroscopy and cavity ringdown spectroscopy in an attempt to develop an air monitoring sensor. The following experiments were then performed determine the sensitivity, durability and dynamic range of these two techniques: flame characterization of HCN and C2H2 in a flame from a Wolfhard-Parker burner, obtaining isolated absorption features of CO, CO2, H 2O, HCN, NH3, CH4, and C2H4 in order to create calibration curves and determine detection limits, CO 2 classroom measurements, and CO2 isotope ratio measurements.

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

    NASA Technical Reports Server (NTRS)

    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 < 2.45 × 10-3 (i.e., <16 Vienna Standard Mean Ocean Water, VSMOW). At R h = 1.2 AU (CRIRES), the production rate for water was Q(H2O) = 1.9 +/- 0.1 × 1029 s-1 and its rotational temperature was T rot 69 K. At R h = 0.75 AU (CSHELL), we measured Q(H2O) = 4.6 +/- 0.6 × 1029 s-1 and T rot = 80 K on March 31, and 6.6 +/- 0.9 × 1029 s-1 and T rot = 100 K on April 1. At R h = 1.74 AU (NIRSPEC), we obtained Q(H2O) = 1.1 +/- 0.1 × 1029 s-1 and T rot 50 K. The measured volatile abundance ratios classify 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

  3. Detection of volatile compounds emitted by Pseudomonas aeruginosa using selected ion flow tube mass spectrometry.

    PubMed

    Carroll, Will; Lenney, Warren; Wang, Tianshu; Spanel, Patrik; Alcock, Alice; Smith, David

    2005-05-01

    Pseudomonas aeruginosa (PA) is associated with a distinctive smell produced by a combination of volatile compounds (VCs). Selected ion flow tube mass spectrometry (SIFT-MS) provides a novel and rapid methodology for rapid, accurate detection of trace quantities (parts per billion; ppb) of VCs in air. We studied the VCs produced by different isolates of PA cultures in vitro from patients with cystic fibrosis. Twenty-one patients with cystic fibrosis provided sputum and cough swab samples for culture. These were used to inoculate blood agar (BA) and Pseudomonas-selective media (PSM). These plates were incubated for 48 hr at 37 degrees C inside sealed plastic bags. The air surrounding the samples after 48 hr (headspace) was analyzed using SIFT-MS. PA growth was commonly associated with the production of significant quantities of VCs, notably hydrogen cyanide gas (HCN). This was detectable in the headspace of 15/22 of PA-positive samples. In contrast, it was only seen in the headspace of 1/13 control samples (6 sterile plates and 7 plates with only mixed upper respiratory tract flora). The concentration of HCN was significantly higher above PA-positive samples than above other bacterial growth (P < 0.01), and in our study, levels of HCN greater than 100 ppb were a sensitive (68%) and highly specific (100%) biomarker of PA. SIFT-MS can detect a range of VCs from PA in vitro. HCN may be a specific indicator of PA infection in vivo, and offers promise as a biomarker for noninvasive detection of PA infection by breath analysis. Copyright 2005 Wiley-Liss, Inc

  4. Development of a cw-laser-based cavity-ringdown sensor aboard a spacecraft for trace air constituents

    NASA Technical Reports Server (NTRS)

    Awtry, A. R.; Miller, J. H.

    2002-01-01

    The progress in the development of a sensor for the detection of trace air constituents to monitor spacecraft air quality is reported. A continuous-wave (cw), external-cavity tunable diode laser centered at 1.55 micrometers is used to pump an optical cavity absorption cell in cw-cavity ringdown spectroscopy (cw-CRDS). Preliminary results are presented that demonstrate the sensitivity, selectivity and reproducibility of this method. Detection limits of 2.0 ppm for CO, 2.5 ppm for CO2, 1.8 ppm for H2O, 19.4 ppb for NH3, 7.9 ppb for HCN and 4.0 ppb for C2H2 are calculated.

  5. Desensitization of chemical activation by auxiliary subunits: convergence of molecular determinants critical for augmenting KCNQ1 potassium channels.

    PubMed

    Gao, Zhaobing; Xiong, Qiaojie; Sun, Haiyan; Li, Min

    2008-08-15

    Chemical openers for KCNQ potassium channels are useful probes both for understanding channel gating and for developing therapeutics. The five KCNQ isoforms (KCNQ1 to KCNQ5, or Kv7.1 to Kv7.5) are differentially localized. Therefore, the molecular specificity of chemical openers is an important subject of investigation. Native KCNQ1 normally exists in complex with auxiliary subunits known as KCNE. In cardiac myocytes, the KCNQ1-KCNE1 (IsK or minK) channel is thought to underlie the I(Ks) current, a component critical for membrane repolarization during cardiac action potential. Hence, the molecular and pharmacological differences between KCNQ1 and KCNQ1-KCNE1 channels have been important topics. Zinc pyrithione (ZnPy) is a newly identified KCNQ channel opener, which potently activates KCNQ2, KCNQ4, and KCNQ5. However, the ZnPy effects on cardiac KCNQ1 potassium channels remain largely unknown. Here we show that ZnPy effectively augments the KCNQ1 current, exhibiting an increase in current amplitude, reduction of inactivation, and slowing of both activation and deactivation. Some of these are reminiscent of effects by KCNE1. In addition, neither the heteromultimeric KCNQ1-KCNE1 channels nor native I(Ks) current displayed any sensitivity to ZnPy, indicating that the static occupancy by a KCNE subunit desensitizes the reversible effects by a chemical opener. Site-directed mutagenesis of KCNQ1 reveals that residues critical for the potentiation effects by either ZnPy or KCNE are clustered together in the S6 region overlapping with the critical gating determinants. Thus, the convergence of potentiation effects and molecular determinants critical for both an auxiliary subunit and a chemical opener argue for a mechanistic overlap in causing potentiation.

  6. DDT_jcernich_10: Time Variability of Thermal Molecular Line Emission in IRC+10216 (4th Epoch)

    NASA Astrophysics Data System (ADS)

    Cernicharo, J.

    2013-04-01

    We have found during our GT line survey of IRC+10216 and the search for hydrides (OT1 proposal) that some molecular lines present a strong intensity variation with time due to the role of infrared pumping. For some lines the intensity change in six months reaches a factor 3 (CCH). We have checked that the effect is not instrumental and than it arises from physical processes ignored so far in the radiative transfer models. We propose to observe the CCH and HNC lines within bands 1a-5b of HIFI every four months (three observing slots) to allow a detailed study of the variation of thermal molecular emission, and dust emission, in this prototype of AGB C-rich object. The settings will also provide, as a bonus, many lines of SiO, SiS, CS, HCN, CO and 13CO for which intensity variations of up to 30% have been found. In addition, a few specificc settings for HCN and CO will complete the observations. SPIRE and PACS observations will complement, with lower spectral resolution, the whole spectrum of each of these molecules and will provide a global view of the total intensity change of these lines with time. A crude estimate of the distance could be also obtained from the observed time lags between the blue and red parts of the line profiles observed with HIFI.

  7. Does the LFIR-LHCN Correlation Hold for Low LFIR Isolated Galaxies?

    NASA Astrophysics Data System (ADS)

    Flaquer, B. O.; Leon, S.; Espada, D.; Martín, S.; Lisenfeld, U.; Verley, S.; Sabater, J.; Verdes-Montenegro, L.

    2010-10-01

    Gao & Solomon (2004a,b) (GS) found a tight linear correlation between LFIR, a good tracer of the SF rate, and LHCN, probing the dense molecular gas for IR-Luminous galaxies. It is open whether this correlation is also followed by galaxies with less active SF. We observed in HCN(1-0) 15 Isolated Galaxies (IG) from the AMIGA sample (VerdesMontenegro et al. 2005) with the IRAM 30m, with the purpose to test whether the GS relation is independent of environment and luminosity. We found that IG have lower LHCN than expected (Fig.1a), with LHCN / LCO ˜ 0.05. However, this might be due to extended HCN missed by our observations in most cases only done at one central pointing. Four galaxies of our sample were mapped. In 2 of them there is substantial emission outside the central parts (Fig.1b+c), and their LHCN value derived from the mapping, follows much closer the relation from GS. Further mapping is needed.

  8. Anisotropic reversed micelles with fluorocarbon-hydrocarbon hybrid surfactants in supercritical CO2.

    PubMed

    Sagisaka, Masanobu; Ono, Shinji; James, Craig; Yoshizawa, Atsushi; Mohamed, Azmi; Guittard, Frédéric; Enick, Robert M; Rogers, Sarah E; Czajka, Adam; Hill, Christopher; Eastoe, Julian

    2018-08-01

    Previous work (M. Sagisaka, et al. Langmuir 31 (2015) 7479-7487), showed the most effective fluorocarbon (FC) and hydrocarbon (HC) chain lengths in the hybrid surfactants FCm-HCn (sodium 1-oxo-1-[4-(perfluoroalkyl)phenyl]alkane-2-sulfonates, where m = FC length and n = HC length) were m and n = 6 and 4 for water solubilization, whereas m 6 and n 6, or m 6 and n 5, were optimal chain lengths for reversed micelle elongation in supercritical CO 2 . To clarify why this difference of only a few methylene chain units is so effective at tuning the solubilizing power and reversed micelle morphology, nanostructures of water-in-CO 2 (W/CO 2 ) microemulsions were investigated by high-pressure small-angle neutron scattering (SANS) measurements at different water-to-surfactant molar ratios (W 0 ) and surfactant concentrations. By modelling SANS profiles with cylindrical and ellipsoidal form factors, the FC6-HCn/W/CO 2 microemulsions were found to increase in size with increasing W 0 and surfactant concentration. Ellipsoidal cross-sectional radii of the FC6-HC4/W/CO 2 microemulsion droplets increased linearly with W 0 , and finally reached ∼39 Å and ∼78 Å at W 0  = 85 (close to the upper limit of solubilizing power). These systems appear to be the largest W/CO 2 microemulsion droplets ever reported. The aqueous domains of FC6-HC6 rod-like reversed micelles increased in size by 3.5 times on increasing surfactant concentration from 35 mM to 50 mM: at 35 mM, FC6-HC5 formed rod-like reversed micelles 5.3 times larger than FC6-HC6. Interestingly, these results suggest that hybrid HC-chains partition into the microemulsion aqueous cores with the sulfonate headgroups, or at the W/CO 2 interfaces, and so play important roles for tuning the W/CO 2 interfacial curvature. The super-efficient W/CO 2 -type solubilizer FC6-HC4, and the rod-like reversed micelle forming surfactant FC6-HC5, represent the most successful cases of low fluorine content additives

  9. Angiotensin II promotes differentiation of mouse c-kit-positive cardiac stem cells into pacemaker-like cells

    PubMed Central

    XUE, CHENG; ZHANG, JUN; LV, ZHAN; LIU, HUI; HUANG, CONGXIN; YANG, JING; WANG, TEN

    2015-01-01

    Cardiac stem cells (CSCs) can differentiate into cardiac muscle-like cells; however, it remains unknown whether CSCs may possess the ability to differentiate into pacemaker cells. The aim of the present study was to determine whether angiotensin II (Ang II) could promote the specialization of CSCs into pacemaker-like cells. Mouse CSCs were treated with Ang II from day 3–5, after cell sorting. The differentiation potential of the cells was then analyzed by morphological analysis, flow cytometry, reverse transcription-polymerase chain reaction, immunohistochemistry and patch clamp analysis. Treatment with Ang II resulted in an increased number of cardiac muscle-like cells (32.7±4.8% vs. 21.5±4.8%; P<0.05), and inhibition of smooth muscle-like cells (6.2±7.3% vs. 20.5±5.1%; P<0.05). Following treatment with Ang II, increased levels of the cardiac progenitor-specific markers GATA4 and Nkx2.5 were observed in the cells. Furthermore, the transcript levels of pacemaker function-related genes, including hyperpolarization-activated cyclic nucleotide-gated (HCN)2, HCN4, T-box (Tbx)2 and Tbx3, were significantly upregulated. Immunofluorescence analysis confirmed the increased number of pacemaker-like cells. The pacemaker current (If) was recorded in the cells derived from CSCs, treated with Ang II. In conclusion, treatment of CSCs with Ang II during the differentiation process modified cardiac-specific gene expression and resulted in the enhanced formation of pacemaker-like cells. PMID:25572000

  10. The cyanogenic syndrome in rubber tree Hevea brasiliensis: tissue-damage-dependent activation of linamarase and hydroxynitrile lyase accelerates hydrogen cyanide release

    PubMed Central

    Kadow, Daniel; Voß, Karsten; Selmar, Dirk; Lieberei, Reinhard

    2012-01-01

    Background and Aims The release of hydrogen cyanide (HCN) from injured plant tissue affects multiple ecological interactions. Plant-derived HCN can act as a defence against herbivores and also plays an important role in plant–pathogen interactions. Crucial for activity as a feeding deterrent is the amount of HCN generated per unit time, referred to as cyanogenic capacity (HCNc). Strong intraspecific variation in HCNc has been observed among cyanogenic plants. This variation, in addition to genotypic variability (e.g. in Trifolium repens), can result from modifications in the expression level of the enzymes involved in either cyanogenic precursor formation or HCN release (as seen in Sorghum bicolor and Phaseolus lunatus). Thus, a modification or modulation of HCNc in reaction to the environment can only be achieved from one to the next generation when under genetic control and within days or hours when transcriptional regulations are involved. In the present study, it is shown that in rubber tree (Hevea brasiliensis) HCNc is modulated by post-translational activity regulation of the key enzymes for cyanide release. Methods Linamarase (LIN) and hydroxynitrile lyase (HNL) activity was determined by colorimetric assays utilizing dissociation of the substrates p-nitrophenyl-β-d-glucopyranoside and acetone cyanohydrin, respectively. Key Results In rubber tree leaves, LIN and HNL show up to ten-fold increased activity in response to tissue damage. This enzyme activation occurs within seconds and results in accelerated HCN formation. It is restricted to the damaged leaf area and depends on the severity of tissue damage. Conclusions LIN and HNL activation (in contrast to genetic and transcriptional regulations) allows an immediate, local and damage type-dependent modulation of the cyanogenic response. Accordingly, this post-translational activation plays a decisive role in the defence of H. brasiliensis against herbivores as well as pathogens and may allow more flexible

  11. Detection of a new interstellar molecule, H2CN

    NASA Technical Reports Server (NTRS)

    Ohishi, Masatoshi; Mcgonagle, Douglas; Irvine, William M.; Yamamoto, Satoshi; Saito, Shuji

    1994-01-01

    We have detected a new interstellar molecule, H2CN (methylene amidogen), in the cold, dark molecular cloud TMC-1. The column density of H2CN is estimated to be approximately 1.5 x 10(exp 11) cm(exp -2) by assuming an excitation temperature of 5 K. This column density corresponds to a fractional abundance relative to H2 of approximately 1.5 x 10(exp -11). This value is more than three orders of magnitude less than the abundance of the related molecule HCN in TMC-1. We also report a tentative detection of H2CN in Sgr B2(N). The formation mechanism of H2CN is discussed. Our detection of the N2CN molecule may suggest the existence of a new series of carbon-chain molecules, CH2C(n)N (N = 0, 1, 2, ...).

  12. A Tale of “Two” Comets: The Primary Volatile Composition of Comet 2P/Encke Across Apparitions

    NASA Astrophysics Data System (ADS)

    Roth, Nathan X.; Gibb, Erika L.; Bonev, Boncho P.; DiSanti, Michael A.; Dello Russo, Neil; Vervack, Ronald J.; McKay, Adam J.; Kawakita, Hideyo

    2017-10-01

    2P/Encke is one of the most frequently observed comets in history, yet its highly favorable 2017 apparition allowed the first comprehensive comparison of primary volatile abundances in the same comet across multiple apparitions. It offered an opportunity to address pressing questions in cometary science, including investigating evolutionary and/or heliocentric distance effects on volatile production, sampling the hypervolatiles CO and CH4 in an ecliptic comet, and probing volatile release at small Rh (0.4 AU). The faint nature of ecliptic comets and low geocentric velocity during most apparitions make these observations in the near-infrared rare (in particular at small Rh) and of high scientific impact. On March 21, 22, and 25 we characterized the volatile composition of 2P post-perihelion using the high-resolution near-infrared iSHELL spectrograph at the 3 m NASA-IRTF on Maunakea, HI. We detected fluorescent emission from eight primary volatiles (H2O, CO, C2H6, CH3OH, CH4, H2CO, NH3, and HCN) and three secondary volatiles (OH*, NH2, and CN). Upper limits were derived for OCS and C2H2. We report rotational temperatures, production rates, and mixing ratios (with respect to H2O). Compared to median relative abundances in comets observed in the near-infrared to date, mixing ratios of trace gases in 2P/Encke are depleted for all detected species except HCN and NH3, which are consistent with the median. The detection of the hypervolatiles CO and CH4 is particularly notable given the paucity of measurements of these species in ecliptic comets. We observed significant differences in primary volatile composition compared to published pre-perihelion results from the 2003 apparition at larger Rh (~1.2 AU) (Radeva et al. 2013). We will discuss possible mechanisms for these effects, including asymmetry about perihelion in 2P (Sekanina 1988a, b), and discuss the results in the context of findings from the Rosetta mission and ground-based studies of comets. This work was

  13. Effect of harvesting frequency, variety and leaf maturity on nutrient composition, hydrogen cyanide content and cassava foliage yield.

    PubMed

    Hue, Khuc Thi; Thanh Van, Do Thi; Ledin, Inger; Wredle, Ewa; Spörndly, Eva

    2012-12-01

    The experiment studied the effect of harvesting frequencies and varieties on yield, chemical composition and hydrogen cyanide content in cassava foliage. Foliage from three cassava varieties, K94 (very bitter), K98-7 (medium bitter) and a local (sweet), were harvested in three different cutting cycles, at 3, 6 and 9 months; 6 and 9 months and 9 months after planting, in a 2-yr experiment carried out in Hanoi, Vietnam. Increasing the harvesting frequency increased dry matter (DM) and crude protein (CP) production in cassava foliage. The K94 variety produced higher foliage yields than the other two varieties. Dry matter, neutral detergent fibre (NDF), acid detergent fibre (ADF) and total tannin content increased with months to the first harvest, whereas CP content decreased. Hydrogen cyanide (HCN) content was lower at the first harvest than at later harvests for all cutting cycles. At subsequent harvests the content of total tannins tended to decline, while HCN content increased (p<0.05). Chemical composition differed somewhat across varieties except for total tannins and ash. Dry matter, NDF, ADF and total tannins were higher in fully matured leaves, while CP and HCN were lower in developing leaves.

  14. Effect of Harvesting Frequency, Variety and Leaf Maturity on Nutrient Composition, Hydrogen Cyanide Content and Cassava Foliage Yield

    PubMed Central

    Hue, Khuc Thi; Thanh Van, Do Thi; Ledin, Inger; Wredle, Ewa; Spörndly, Eva

    2012-01-01

    The experiment studied the effect of harvesting frequencies and varieties on yield, chemical composition and hydrogen cyanide content in cassava foliage. Foliage from three cassava varieties, K94 (very bitter), K98-7 (medium bitter) and a local (sweet), were harvested in three different cutting cycles, at 3, 6 and 9 months; 6 and 9 months and 9 months after planting, in a 2-yr experiment carried out in Hanoi, Vietnam. Increasing the harvesting frequency increased dry matter (DM) and crude protein (CP) production in cassava foliage. The K94 variety produced higher foliage yields than the other two varieties. Dry matter, neutral detergent fibre (NDF), acid detergent fibre (ADF) and total tannin content increased with months to the first harvest, whereas CP content decreased. Hydrogen cyanide (HCN) content was lower at the first harvest than at later harvests for all cutting cycles. At subsequent harvests the content of total tannins tended to decline, while HCN content increased (p<0.05). Chemical composition differed somewhat across varieties except for total tannins and ash. Dry matter, NDF, ADF and total tannins were higher in fully matured leaves, while CP and HCN were lower in developing leaves. PMID:25049534

  15. Multiple outflows in the bipolar planetary nebula M1-16: A molecular line study

    NASA Astrophysics Data System (ADS)

    Sahai, Raghvendra; Wootten, Alwyn; Schwarz, Hugo E.; Wild, W.

    1994-06-01

    Extensive observations of the molecular gas in the young, compact planetary nebula M1-16 have been made, using the Swedish-ESO-Submillimeter Telescope. A map of the CO J = 2-1 emission shows that the molecular envelope contains both a slow and a fast outflow with expansion velocities of 19 km/s and greater than 34 km/s, respectively. The slow outflow is mildly elliptical, while the fast molecular outflow is bipolar. This fast outflow is roughly aligned with the very fast outflows recently found in the optical, while the long axis of the slow elliptical outflow is roughly orthogonal to the optical outflow axis. The kinematic timescales for the CO fast outflow and the optical very fast outflow agree closely, supporting the view that the former represents material in the slow outflow accelerated by the very fast outflow. The kinematic signature of a disk expanding with about 15.5 km/s can also be seen in the CO J = 2-1 data. The mass-loss rate (a) for the slow outflow is greater than or equal to 2.8 x 10-5 solar mass/yr and possibly as large as 9 x 10-5 solar mass/yr, (b) for the fast outflow is greater than or equal to 5 x 10-6 solar mass/yr, and (c) for the very fast optically visible outflow is approximately equal 5 x 10-7 solar mass/yr. The disk mass is approximately equal 6 x 10-3 solar mass. Grain photoelectric heating results in temperatures of 20-70 K in molecular gas of the slow outflow. The (13)C/(12)C abundance ratio in M1-16 is found to be 0.33, quite possibly the highest found for any evolved object. Upper limits for the (18)O/(16)O and (17)O/(16)O ratios were found to be consistent with the values found in AGB stars. A search for other molecular species in M1-16 resulted in the detection of the high-excitation species HCN, CN, (13)CN, HCO(+), and H(13)CO(+) and possibly N2H(+). Both the HCO(+)/HCN and CN/HCN line-intensity ratios are enhanced, the former by a very large factor, over the values found in the envelopes of AGB stars, probably as a result of

  16. Pre- and Post-Perihelion Observations of C/2009 P1 (Garradd): Evidence for an Oxygen-Rich Heritage?

    NASA Astrophysics Data System (ADS)

    DiSanti, Michael A.; Villanueva, G. L.; Paganini, L.; Bonev, B. P.; Keane, J. V.; Meech, K. J.; Mumma, M. J.

    2013-10-01

    We present pre- and post-perihelion observations of Comet C/2009 P1 (Garradd), on UT 2011 October 13 (heliocentric distance Rh = 1.83 AU) and 2012 January 8 (Rh = 1.57 AU), respectively, using the high-resolution infrared spectrometer (NIRSPEC) on the Keck II 10-m telescope on Mauna Kea, HI. On October 13, we obtained production rates for nine primary volatiles (native ices): H2O, CO, CH3OH, CH4, C2H6, HCN, C2H2, H2CO, and NH3. On January 8, we obtained production rates for three of these (H2O, CH4, and HCN) and sensitive upper limits for three others (C2H2, H2CO, and NH3). CO was enriched and C2H2 was depleted, yet C2H6 and CH3OH were close to their current mean values as measured in a dominant group of Oort cloud comets. We compare the composition of Garradd with other CO-rich comets C/1999 T1 (McNaught-Hartley), C/1996 B2 (Hyakutake), and C/1995 O1 (Hale-Bopp), and with other comets in our database. We discuss possible implications regarding the processing history of its pre-cometary ices. Our measurements of C/2009 P1 indicate consistent pre- and post-perihelion abundance ratios for trace species relative to H2O, suggesting we were measuring a homogeneous composition to the depths sampled in the nucleus. The overall gas production was lower post-perihelion despite its smaller heliocentric distance on January 8. This is qualitatively consistent with other studies of C/2009 P1. On October 13, the water profile showed a pronounced excess towards the Sun-facing hemisphere that was not seen in other molecules nor in the dust continuum. Inter-comparison of profiles from October 13 permitted us to estimate the fraction of all H2O released in the coma and contained within our slit. We attribute this excess H2O to release from relatively pure, water-rich icy grains. Similar evidence for extended release was not observed on January 8 and this, together with its overall lower gas production post-perihelion, suggests loss of one or more active regions on the nucleus

  17. Path integrals with higher order actions: Application to realistic chemical systems

    NASA Astrophysics Data System (ADS)

    Lindoy, Lachlan P.; Huang, Gavin S.; Jordan, Meredith J. T.

    2018-02-01

    Quantum thermodynamic parameters can be determined using path integral Monte Carlo (PIMC) simulations. These simulations, however, become computationally demanding as the quantum nature of the system increases, although their efficiency can be improved by using higher order approximations to the thermal density matrix, specifically the action. Here we compare the standard, primitive approximation to the action (PA) and three higher order approximations, the Takahashi-Imada action (TIA), the Suzuki-Chin action (SCA) and the Chin action (CA). The resulting PIMC methods are applied to two realistic potential energy surfaces, for H2O and HCN-HNC, both of which are spectroscopically accurate and contain three-body interactions. We further numerically optimise, for each potential, the SCA parameter and the two free parameters in the CA, obtaining more significant improvements in efficiency than seen previously in the literature. For both H2O and HCN-HNC, accounting for all required potential and force evaluations, the optimised CA formalism is approximately twice as efficient as the TIA formalism and approximately an order of magnitude more efficient than the PA. The optimised SCA formalism shows similar efficiency gains to the CA for HCN-HNC but has similar efficiency to the TIA for H2O at low temperature. In H2O and HCN-HNC systems, the optimal value of the a1 CA parameter is approximately 1/3 , corresponding to an equal weighting of all force terms in the thermal density matrix, and similar to previous studies, the optimal α parameter in the SCA was ˜0.31. Importantly, poor choice of parameter significantly degrades the performance of the SCA and CA methods. In particular, for the CA, setting a1 = 0 is not efficient: the reduction in convergence efficiency is not offset by the lower number of force evaluations. We also find that the harmonic approximation to the CA parameters, whilst providing a fourth order approximation to the action, is not optimal for these

  18. Atmos/Atlas 3 Infrared Profile Measurements of Trace Gases in The November 1994 Tropical and Subtropical Upper Troposphere

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Gunson, M. R.; Wang, P.-H.; Arduini, R. F.; Baum, B. A.; Minnis, P.; Minnis, P.; Goldman, A.; Abrams, M. C.; Zander, R.; hide

    1998-01-01

    Vertical mixing ratio profiles of four relatively long-lives gases, HCN, C2H2, CO, and C2H6, have been retrieved from 0.01/cm resolution infrared solar occultation spectra recorded between latitudes of 5.3degN and 31.4degN. The observations were obtained by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer during the Atmospheric Laboratory for Applications and Science (ATLAS) 3 shuttle flight, 3-12 November 1994. Elevated mixing ratios below the tropopause were measured for these gases during several of the occultations. The positive correlations obtained between the simultaneously measured mixing ratios suggest that the enhancements are likely the result of surface emissions, most likely biomass burning and/or urban industrial activities, followed by common injection via deep convective transport of the gases to the upper troposphere. The elevated levels of HCN may account for at least part of the "missing NO," in the upper troposphere. Comparisons of the observations with values measured during a recent aircraft campaign are presented.

  19. Polyimine and its potential significance for prebiotic chemistry on Titan

    NASA Astrophysics Data System (ADS)

    Rahm, Martin; Lunine, Jonathan I.; Usher, David; Shalloway, David

    2016-10-01

    Hydrogen cyanide (HCN), a key reagent in prebiotic chemistry, is being generated in large amounts in the atmosphere of Titan. Contradictions between Cassini-Huygens measurements of the atmosphere and the surface of Titan, suggest that HCN is undergoing reaction chemistry, despite the frigid temperatures of 90-94 K. We will discuss computational results [1] investigating polyimine as one potential explanation for this observation. Polyimine is a polymer identified as the major component of polymerized HCN in laboratory experiments. It is flexible, which aids low temperature mobility, and it is able to form intermolecular and intramolecular =N-H...N hydrogen bonds, allowing for different polymorphs. Polymorphs have been predicted and explored by density functional theory coupled with a structure-searching algorithm. We have calculated the thermodynamics of polymerization, and show that polyimine is capable of absorbing light in a window of relative transparency in Titan's atmosphere. Light absorption and the possible catalytic functions of polyimine are suggestive of it driving photochemistry on the surface, with potential prebiotic implications.References:[1] M. Rahm, J. I. Lunine, D. Usher, D. Shalloway, "Polymorphism and electronic structure of polyimine and its potential significance for prebiotic chemistry on Titan", PNAS, early view. doi: 10.1073/pnas.1606634113

  20. Observations of Infrared Molecular Lines Toward the Massive Protostar GL 2591

    NASA Astrophysics Data System (ADS)

    Knez, C.; Boonman, A. M. S.; Lacy, J. H.; Evans, N. J., II; Richter, M. J.

    2001-12-01

    Using TEXES (Texas Echelon Cross Echelle Spectrograph) at the NASA Infrared Telescope Facility, we have observed rovibrational transitions of C2H2 and HCN near 13 microns in absorption toward the deeply embedded, massive protostar, GL 2591. GL 2591 is obscured by about 70 magnitudes of visual extinction; however, it is one of the brightest mid-infrared sources. The following lines were observed: C2H2 R(5), R(6), R(12), and R(13) and HCN R(10) and R(16). With a spectral resolution of ~ 3 km/s, all lines are resolved. We show the line profiles and compare the spectra to previous results from Carr et al. (1995), Lahuis & van Dishoeck (2000) and Boonman et al. (2001). Observations with TEXES were supported by the Texas Advanced Research Program.

  1. Infrared study of matrix-isolated ethyl cyanide: simulation of the photochemistry in the atmosphere of Titan.

    PubMed

    Toumi, A; Piétri, N; Couturier-Tamburelli, I

    2015-11-11

    Low-temperature Ar matrix isolation has been carried out to investigate the infrared spectrum of ethyl cyanide (CH3CH2CN), a molecule present in the atmosphere of Titan. The λ > 120 nm and λ > 230 nm photolysis reactions of ethyl cyanide in an Ar matrix were also performed in order to compare the behaviour of this compound when it is submitted to high and low energetic radiations. These different wavelengths have been used with the aim to reproduce the radiation reaching the various parts of the atmosphere. Several photoproducts have been identified during photolysis such as vinyl cyanide (CH2[double bond, length as m-dash]CHCN), cyanoacetylene (HC3N), and ethylene/hydrogen cyanide (C2H4/HCN), ethylene/hydrogen isocyanide (C2H4/HNC), acetylene/hydrogen cyanide (C2H2/HCN), acetylene/hydrogen isocyanide (C2H2/HNC), and acetylene:methylenimine (C2H2:HNCH2) complexes. Ethyl isocyanide (CH3CH2NC) and a ketenimine form (CH3CH[double bond, length as m-dash]C[double bond, length as m-dash]NH) have been identified as well. Photoproduct identification and spectral assignments were done using previous studies and density functional theory (DFT) calculations with the B3LYP/cc-pVTZ basis set.

  2. Acrylonitrile characterization and high energetic photochemistry at Titan temperatures

    NASA Astrophysics Data System (ADS)

    Toumi, A.; Piétri, N.; Chiavassa, T.; Couturier-Tamburelli, I.

    2016-05-01

    Laboratory infrared spectra of amorphous and crystalline acrylonitrile (C2H3CN) ices were recorded between 4000 and 650 cm-1. Heating up the acrylonitrile sample to 160 K shows details on the transition between amorphous and crystalline ice at ∼94 K. This molecule can be used as an indicator of the surface temperature of Titan since it is known also to be ∼94 K. The desorption energy of acrylonitrile was determined using two methods (IRTF and mass spectrometries) to be around 35 kJ mol-1. Solid phase acrylonitrile was irradiated with vacuum ultraviolet (VUV) light at low temperatures (20, 70, 95 and 130 K) using a microwave-discharge hydrogen flow lamp. Isoacrylonitrile, cyanoacetylene (HC3N), isocyanoacetylene (HC2NC), acetylene (C2H2) and hydrogen cyanide (HCN) were identified as photoproducts by using FTIR spectroscopy. The branching ratio of each pathway has been calculated for the different temperatures. We have estimated the acrylonitrile, HCN and HC3N νCtbnd N stretching band strengths to be respectively A = 3.98 ×10-18 , A = 1.38 ×10-18 and A = 2.92 ×10-18cmmolecule-1 .

  3. Ion-molecule condensation reactions: a mechanism for organic synthesis in ionized reducing atmospheres.

    PubMed

    Meot-Ner, M

    1978-12-01

    The CH3+ ion, formed in ionized methane, undergoes consecutive eliminative condensation reactions with methane to form the carbonium ions C2H5+, i-C3H7+ and t-C4H9+. At T smaller than 500 degrees K, NCH4 greater than 10(16) cm-3 these ions react with NH3 in competitive condensation -- H+ transfer reactions, e.g. C2H5 + NH3 M leads to C2H5NH3+ leads to NH4+ + C2H4 At particle densities of NCH4 smaller than 10(16) cm-3 proton transfer is the only significant reaction channel. At NCH4 greater than 10(17) cm-3 condensation constitutes 5--20% of the overall reactions. The product of the condensation reaction further associates with CO2 to form C2H5NH3+ . CO2; the atomic composition of this cluster ion is identical with the protonated amino acid alanine. The carbonium ions i-C3H7+ and t-C4H9+ condense also with HCN to yield protonated isocyanides. HCNH% also appears to condense with HCN at T greater than 570 degrees K, and form cluster ions with HCN at lower temperatures. The rate constants of the condensation reactions vary with temperature and pressure in a complex manner. Under conditions similar to those on Titan at an altitude of 100 km (T = 100--150 degrees K, NCH4 approximately 10(18) cm-3), with a methane atmosphere containing 1% H2 and traces of NH3 and H2O, ion-molecule condensation reactions followed by H+ transfer are expected to lead to the atmospheric synthesis of C2H6, C3H8, CH3OH, C2H5OH and the terminal ions NH4+, CH3NH3+ and C2H5NH3+. At higher temperatures (250 degrees K smaller than T smaller than 400 degrees K), the synthesis of i-C4H10, i-C3H7OH and t-C4H9OH and of the ions i-C3H7NH3+ and t-C4H9NH3+ is also expected. Electron recombination of the terminal ions may yield amines, imines and nitriles. Cycles of protonation and dissociative recombination of the alkanes and alcohols produced in condensation reactions will also produce unsaturated hydrocarbons, ketones and aldehydes in the ionized atmosphere.

  4. Morphological and physiological analysis of type-5 and other bipolar cells in the Mouse Retina.

    PubMed

    Hellmer, C B; Zhou, Y; Fyk-Kolodziej, B; Hu, Z; Ichinose, T

    2016-02-19

    Retinal bipolar cells are second-order neurons in the visual system, which initiate multiple image feature-based neural streams. Among more than ten types of bipolar cells, type-5 cells are thought to play a role in motion detection pathways. Multiple subsets of type-5 cells have been reported; however, detailed characteristics of each subset have not yet been elucidated. Here, we found that they exhibit distinct morphological features as well as unique voltage-gated channel expression. We have conducted electrophysiological and immunohistochemical analysis of retinal bipolar cells. We defined type-5 cells by their axon terminal ramification in the inner plexiform layer between the border of ON/OFF sublaminae and the ON choline acetyltransferase (ChAT) band. We found three subsets of type-5 cells: XBCs had the widest axon terminals that stratified at a close approximation of the ON ChAT band as well as exhibiting large voltage-gated Na(+) channel activity, type-5-1 cells had compact terminals and no Na(+) channel activity, and type-5-2 cells contained umbrella-shaped terminals as well as large voltage-gated Na(+) channel activity. Hyperpolarization-activated cyclic nucleotide-gated (HCN) currents were also evoked in all type-5 bipolar cells. We found that XBCs and type-5-2 cells exhibited larger HCN currents than type-5-1 cells. Furthermore, the former two types showed stronger HCN1 expression than the latter. Our previous observations (Ichinose et al., 2014) match the current study: low temporal tuning cells that we named 5S corresponded to 5-1 in this study, while high temporal tuning 5f cells from the previous study corresponded to 5-2 cells. Taken together, we found three subsets of type-5 bipolar cells based on their morphologies and physiological features. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  5. Cosmic ray processing of N2-containing interstellar ice analogues at dark cloud conditions

    NASA Astrophysics Data System (ADS)

    Fedoseev, G.; Scirè, C.; Baratta, G. A.; Palumbo, M. E.

    2018-04-01

    N2 is believed to lock considerable part of nitrogen elemental budget and, therefore, to be one of the most abundant ice constituent in cold dark clouds. This laboratory-based research utilizes high energetic processing of N2 containing interstellar ice analogues using 200 keV H+ and He+ ions that mimics cosmic ray processing of the interstellar icy grains. It aims to investigate the formation of (iso)cyanates and cyanides in the ice mantles at the conditions typical for cold dark clouds and prestellar cores. Investigation of cosmic ray processing as a chemical trigger mechanism is explained by the high stability of N2 molecules that are chemically inert in most of the atom- and radical-addition reactions and cannot be efficiently dissociated by cosmic ray induced UV-field. Two sets of experiments are performed to closer address solid-state chemistry occurring in two distinct layers of the ice formed at different stages of dark cloud evolution, i.e. `H2O-rich' and `CO-rich' ice layers. Formation of HNCO and OCN- is discussed in all of the performed experiments. Corresponding kinetic curves for HNCO and OCN- are obtained. Furthermore, a feature around 2092 cm-1 assigned to the contributions of 13CO, CN-, and HCN is analysed. The kinetic curves for the combined HCN/CN- abundance are derived. In turn, normalized formation yields are evaluated by interpolation of the obtained results to the low irradiation doses relevant to dark cloud stage. The obtained values can be used to interpret future observations towards cold dark clouds using James Webb Space Telescope.

  6. Some new results on shock chemistry in IC 443

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    New observations have been made of CO, CO-13, SiO, SO, H2CO, HCO(+), N2H(+), CS, OCS, HCN, and OH in the shocked clouds of IC 443. It is found that at position IC 443 B, (1) the shocked CO is optically thin; (2) the HCO(+)/CO abundance ratio is 4-9 x 10 to the -4 th, representing a tenfold enhancement over that of normal interstellar clouds; (3) there is no enhancement of SO or SIO, as occurs in Orion KL; and (4) there is optically thin preshock OH, confirming a hundredfold enhancement of the OH/CO ratio in the shock.

  7. Stellar and Circumstellar Properties of the Pre-Main-Sequence Binary GV Tau From Infrared Spectroscopy

    DTIC Science & Technology

    2008-09-20

    surface gravity . With ourL-band spectra in order 25 (3.0450Y3.0865m;Fig. 1e), we detect strong HCN absorption (10% deep) and weaker C2H2 absorption in...Doppmann et al. 2005). The absorption lines of Na i and Mg i are particularly gravity and temperature sensitive, but in the opposite sense from each...other. For example, at cool effective temperatures (3200Y4500 K) and subdwarf surface gravities (3:5 log g 4:5) Na andMg lines both grow stronger as

  8. Isotopic Ratios of H, C, N, O, and S in Comets C2012 F6 (lemmon) and C2014 Q2 (lovejoy) * ** ***

    NASA Technical Reports Server (NTRS)

    Biver, N.; Moreno, R.; Sandqvist, Aa.; Bockelee-Morvan, D.; Colom, P.; Crovisier, J.; Lis, D. C.; Bossier, J.; Debout, V.; Paubert, G.; hide

    2016-01-01

    The apparition of bright comets C/2012 F6 (Lemmon) and C/2014 Q2 (Lovejoy) in March-April 2013 and January 2015, combined with the improved observational capabilities of submillimeter facilities, offered an opportunity to carry out sensitive compositional and isotopic studies of the volatiles in their coma. We observed comet Lovejoy with the IRAM 30 meter telescope between 13 and 26 January 2015, and with the Odin submillimeter space observatory on 29 January - 3 February 2015. We detected 22 molecules and several isotopologues. The H2 O-16 and H2 O-18 production rates measured with Odin follow a periodic pattern with a period of 0.94 days and an amplitude of approximately 25 percent. The inferred isotope ratios in comet Lovejoy are O-16/O-18 = 499 +/- 24 and D/H equals 1.4 +/- 0.4 x 10(exp -4) in water, S-32/S-34 = equals 24.7 +/- 3.5 in CS, all compatible with terrestrial values. The ratio C-12/C-13 equals 109 +/- 14 in HCN is marginally higher than terrestrial and 14 N/ 15/N equals 145 +/- 12 in HCN is half the Earth ratio. Several upper limits for D/H or C-12/ C-13 in other molecules are reported. From our observation of HDO in comet C/2014 Q2 (Lovejoy), we report the first D/H ratio in an Oort Cloud comet that is not larger than the terrestrial value. On the other hand, the observation of the same HDO line in the other Oort-cloud comet, C/2012 F6 (Lemmon), suggests a D/H value four times higher. Given the previous measurements of D/H in cometary water, this illustrates that a diversity in the D/H ratio and in the chemical composition, is present even within the same dynamical group of comets, suggesting that current dynamical groups contain comets formed at very different places or times in the early solar system.

  9. Hydrogen Cyanide Polymerization: A Preferred Cosmochemical Pathway

    NASA Astrophysics Data System (ADS)

    Matthews, Clifford N.

    In the presence of a base such as ammonia, liquid HCN polymerizes spontaneously at room temperature to a brown-black solid from which a yellow-brown powder can be extracted by water and further hydrolyzed to yield a-amino acids. Two types of structural units appear to be present in these polymeric products, stable ladder polymers with conjugated -C=N- bonds, and polyamidines, readily converted by water to polypeptides. Several kinds of investigations, including electric discharge experiments which produce HCN from methane and ammonia, give results consistent with the hypothesis that the original polypeptides on Earth were synthesized directly from such HCN polymers and water without the intervening formation of -amino acids. In the absence of water - on land - the intermediate polyamidines could have been the original condensing agents directing the synthesisis of nucleosides and nucleotides from available sugars, phosphates and nitrogen bases. Most significant would have been the parallel synthesis of polypeptides and polynucleotides arising from the dehydrating action of these polyamidines on nucleotides.

  10. Biophysics of object segmentation in a collision-detecting neuron

    PubMed Central

    Dewell, Richard Burkett

    2018-01-01

    Collision avoidance is critical for survival, including in humans, and many species possess visual neurons exquisitely sensitive to objects approaching on a collision course. Here, we demonstrate that a collision-detecting neuron can detect the spatial coherence of a simulated impending object, thereby carrying out a computation akin to object segmentation critical for proper escape behavior. At the cellular level, object segmentation relies on a precise selection of the spatiotemporal pattern of synaptic inputs by dendritic membrane potential-activated channels. One channel type linked to dendritic computations in many neural systems, the hyperpolarization-activated cation channel, HCN, plays a central role in this computation. Pharmacological block of HCN channels abolishes the neuron's spatial selectivity and impairs the generation of visually guided escape behaviors, making it directly relevant to survival. Additionally, our results suggest that the interaction of HCN and inactivating K+ channels within active dendrites produces neuronal and behavioral object specificity by discriminating between complex spatiotemporal synaptic activation patterns. PMID:29667927

  11. Risk of hydrocyanic acid release in the electroplating industry.

    PubMed

    Piccinini, N; Ruggiero, G N; Baldi, G; Robotto, A

    2000-01-07

    This paper suggests assessing the consequences of hydrocyanic acid (HCN) release into the air by aqueous cyanide solutions in abnormal situations such as the accidental introduction of an acid, or the insertion of a cyanide in a pickling bath. It provides a well-defined source model and its resolution by methods peculiar to mass transport phenomena. The procedure consists of four stages: calculation of the liquid phase concentration, estimate of the HCN liquid-vapour equilibrium, determination of the mass transfer coefficient at the liquid-vapour interface, evaluation of the air concentration of HCN and of the damage distances. The results show that small baths operating at high temperatures are the major sources of risk. The building up of lethal air concentrations, on the other hand, is governed by the values of the mass transfer coefficient, which is itself determined by the flow dynamics and bath geometry. Concerning the magnitude of the risk, the fallout for external emergency planning is slight in all the cases investigated.

  12. Investigation of "mysterious" disease in livestock: hydrocyanic acid poisoning.

    PubMed

    Krishna, L; Katoch, R C

    1989-12-01

    An investigation of "mysterious" disease due to hydrocyanic acid (HCN) poisoning in livestock in this state was carried out. Detailed clinicopathological and pathological studies were conducted. Characteristic signs of acute tympany followed with profuse frothing, convulsions and dyspnea were recorded. Cynosis of the mucosa with characteristic anoxemic tissue changes and a high concentration of HCN in rumen content, feed and skeletal muscles were recorded. These were sufficient to establish the diagnosis. Successful treatment with a specific antidote was achieved, and further morbidity and mortality was checked.

  13. Identifying fire plumes in the Arctic with tropospheric FTIR measurements and transport models

    NASA Astrophysics Data System (ADS)

    Viatte, C.; Strong, K.; Hannigan, J.; Nussbaumer, E.; Emmons, L. K.; Conway, S.; Paton-Walsh, C.; Hartley, J.; Benmergui, J.; Lin, J.

    2015-03-01

    We investigate Arctic tropospheric composition using ground-based Fourier transform infrared (FTIR) solar absorption spectra, recorded at the Polar Environment Atmospheric Research Laboratory (PEARL, Eureka, Nunavut, Canada, 80°05' N, 86°42' W) and at Thule (Greenland, 76°53' N, -68°74' W) from 2008 to 2012. The target species, carbon monoxide (CO), hydrogen cyanide (HCN), ethane (C2H6), acetylene (C2H2), formic acid (HCOOH), and formaldehyde (H2CO) are emitted by biomass burning and can be transported from mid-latitudes to the Arctic. By detecting simultaneous enhancements of three biomass burning tracers (HCN, CO, and C2H6), ten and eight fire events are identified at Eureka and Thule, respectively, within the 5-year FTIR time series. Analyses of Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model back-trajectories coupled with Moderate Resolution Imaging Spectroradiometer (MODIS) fire hotspot data, Stochastic Time-Inverted Lagrangian Transport (STILT) model footprints, and Ozone Monitoring Instrument (OMI) UV aerosol index maps, are used to attribute burning source regions and travel time durations of the plumes. By taking into account the effect of aging of the smoke plumes, measured FTIR enhancement ratios were corrected to obtain emission ratios and equivalent emission factors. The means of emission factors for extratropical forest estimated with the two FTIR data sets are 0.40 ± 0.21 g kg-1 for HCN, 1.24 ± 0.71 g kg-1 for C2H6, 0.34 ± 0.21 g kg-1 for C2H2, and 2.92 ± 1.30 g kg-1 for HCOOH. The emission factor for CH3OH estimated at Eureka is 3.44 ± 1.68 g kg-1. To improve our knowledge concerning the dynamical and chemical processes associated with Arctic pollution from fires, the two sets of FTIR measurements were compared to the Model for OZone And Related chemical Tracers, version 4 (MOZART-4). Seasonal cycles and day-to-day variabilities were compared to assess the ability of the model to reproduce emissions from fires and

  14. MULTI-WAVELENGTH OBSERVATIONS OF COMET C/2011 L4 (PAN-STARRS)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yang, Bin; Keane, Jacqueline; Meech, Karen

    2014-04-01

    The dynamically new comet C/2011 L4 (Pan-STARRS) is one of the brightest comets observed since the great comet C/1995 O1 (Hale-Bopp). Here, we present our multi-wavelength observations of C/2011 L4 during its in-bound passage to the inner solar system. A strong absorption band of water ice at 2.0 μm was detected in the near-infrared spectra, obtained with the 8 m Gemini-North and 3 m Infrared Telescope Facility Telescopes. The companion 1.5 μm band of water ice, however, was not observed. Spectral modeling shows that the absence of the 1.5 μm feature can be explained by the presence of sub-micron-sized fine ice grains.more » No gas lines (i.e., CN, HCN, or CO) were observed pre-perihelion in either the optical or the submillimeter. We derived 3σ upper limits for the CN and CO production rates. The comet exhibited a very strong continuum in the optical and its slope seemed to become redder as the comet approached the Sun. Our observations suggest that C/2011 L4 is an unusually dust-rich comet with a dust-to-gas mass ratio >4.« less

  15. Identifying fire plumes in the Arctic with tropospheric FTIR measurements and transport models

    NASA Astrophysics Data System (ADS)

    Viatte, C.; Strong, K.; Hannigan, J.; Nussbaumer, E.; Emmons, L.; Conway, S.; Paton-Walsh, C.; Hartley, J.; Benmergui, J.; Lin, J.

    2014-10-01

    We investigate Arctic tropospheric composition using ground-based Fourier Transform Infrared (FTIR) solar absorption spectra, recorded at the Polar Environment Atmospheric Research Laboratory (PEARL, Eureka, Nunavut, Canada, 80°5' N, 86°42' W) and at Thule (Greenland, 76°53' N, -68°74' W) from 2008 to 2012. The target species: carbon monoxide (CO), hydrogen cyanide (HCN), ethane (C2H6), acetylene (C2H2), formic acid (HCOOH), and formaldehyde (H2CO) are emitted by biomass burning and can be transported from mid-latitudes to the Arctic. By detecting simultaneous enhancements of three biomass burning tracers (HCN, CO, and C2H6), ten and eight fire events are identified at Eureka and Thule, respectively, within the five-year FTIR timeseries. Analyses of Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) back-trajectories coupled with Moderate Resolution Imaging Spectroradiometer (MODIS) fire hot spot data, Stochastic Time-Inverted Lagrangian Transport model (STILT) footprints, and Ozone Monitoring Instrument (OMI) UV aerosol index maps are used to attribute burning source regions and travel time durations of the plumes. By taking into account the effect of aging of the smoke plumes, measured FTIR enhancement ratios were corrected to obtain emission ratios and equivalent emission factors. The means of emission factors for extratropical forest estimated with the two FTIR datasets are 0.39 ± 0.15 g kg-1 for HCN, 1.23 ± 0.49 g kg-1 for C2H6, 0.34 ± 0.16 g kg-1 for C2H2, 2.13 ± 0.92 g kg-1 for HCOOH, and 3.14 ± 1.28 g kg-1 for CH3OH. To improve our knowledge concerning the dynamical and chemical processes associated with Arctic pollution from fires, the two sets of FTIR measurements were compared to the Model for Ozone and Related chemical Tracers, version 4 (MOZART-4). Seasonal cycles and day-to-day variabilities were compared to assess the ability of the model to reproduce emissions from fires and their transport. Good agreement in winter

  16. Observations of cometary parent molecules with the IRAM radio telescope

    NASA Technical Reports Server (NTRS)

    Colom, P.; Despois, D.; Paubert, G.; Bockelee-Morvan, D.; Crovisier, Jacques

    1992-01-01

    Several rotational transitions of HCN, H2S, H2CO, and CH3OH were detected in comets P/Brorsen-Metcalf 1989 X, Austin (1989c1) and Levy (1990c) with the Institute for Millimeter Radioastronomy (IRAM) 30-m radio telescope. This allows us to determine the production rates of these molecules and to probe the physical conditions of the coma.

  17. Production of organic compounds in plasmas: A comparison among electric sparks, laser-induced plasmas and UV light

    NASA Technical Reports Server (NTRS)

    Scattergood, T. W.; Mckay, C. P.; Borucki, W. J.; Giver, L. P.; Vanghyseghem, H.; Parris, J. E.; Miller, S. L.

    1991-01-01

    In order to study the production of organic compounds in plasmas (and shocks), various mixtures of N2, CH4, and H2, modeling the atmosphere of Titan, were exposed to discrete sparks, laser-induced plasmas (LIP) and ultraviolet light. The yields of HCN and simple hydrocarbons were measured and compared to those calculated from a simple quenched thermodynamic equilibrium model. The agreement between experiment and theory was fair for HCN and C2H2. However, the yields of C2H6 and other hydrocarbons were much higher than those predicted by the model. Our experiments suggest that photolysis by ultraviolet light from the plasma is an important process in the synthesis. This was confirmed by the photolysis of gas samples exposed to the light, but not to the plasma or shock waves. The results of these experiments demonstrate that, in addition to the well-known efficient synthesis of organic compounds in plasmas, the yields of saturated species, e.g., ethane, may be higher than predicted by theory and that LIP provide a convenient and clean way of simulating planetary lightning and impact plasmas in the laboratory.

  18. Hydrogen cyanide polymers: from laboratory to space

    NASA Astrophysics Data System (ADS)

    Matthews, Clifford N.

    1995-02-01

    Hydrogen cyanide polymers - heterogeneous solids ranging in color from yellow to orange to red to black - may be among the organic macromolecules most readily formed within the solar system The non-volatile black crust of comet Halley for example, may consist largely of such polymers. It seems likely. too, that HCN polymers are a major constituent of the dark. CN bearing solids identified tentatively by IR spectra in the dust of some other comets. HCN polymerization could also account for some of the yellow-orange-red coloration of Jupiter and Saturn, and perhaps for the orange haze high in Titan's atmosphere. Studies of these polymers show that a yellow-brown powder can be extracted by water and further hydrolyzed to vield α-amino acids. Several instrumental methods used for the separation and identification of these intriguing materials. including pyrolysis mass spectrometry, Fourier transform IR photoacoustic spectroscopy and supercritical fluid extraction chromatography, reveal fragmentation patterns and chemical functionalities consistent with the presence of polymeric peptide precursors - polyamidines - in HCN polymers. Implications for prebiotic chemistry are profound. Primitive Earth may have been covered by HCN polymers and other organic products through bolide bombardment or terrestrial synthesis, producing a proteinaceous matrix able to bring about the molecular interactions leading to the emergence or life. Cyanide polymerization could also he a preferred pathway beyond Earth and the solar system, on planetary bodies and satellites around other stars and in the dusty molecular clouds of spiral galaxies.

  19. Spatial variation of the physical conditions of molecular gas in galaxies

    NASA Technical Reports Server (NTRS)

    Jackson, James M.; Eckart, Andreas; Wild, Wolfgang; Genzel, Reinhard; Harris, Andrew I.; Downes, Dennis; Jaffe, D. T.; Ho, Paul T. P.

    1990-01-01

    Multi-line studies of CO-12, CO-13, C-18O, HCN, and HCO(+) at 3 mm, 1.3 mm, and 0.8 mm using the Institute for Radio Astronomy in the Millimeter range (IRAM) 30 m telescope, with the IRAM superconductor insulator superconductor (SIS) receivers and the Max Planck Institute for External Physics (MPE) 350 GHz SIS receiver, show that the densities and temperatures of molecular gas in external galaxies change significantly with position. CO-12 measures the densities and temperature of diffuse interclump molecular gas, but not the bulk of the molecular gas. Simple one-component models, with or without external heating, cannot account for the weakness of the CO-12 J = 3 to 2 line relative to J = 2 to 1 and J = 1 to 0. CO-12 does not trace the bulk of the molecular gas, and optical depth effects obviate a straightforward interpretation of CO-12 data. Instead, researchers turned to the optically thin CO isotopes and other molecular species. Isotopic CO lines measure the bulk of the molecular gas, and HCN and HCO(+) pick out denser regions. Researchers find a warm ridge of gas in IC 342 (Eckart et al. 1989), denser gas in the starburst nucleus of IC 342, and a possible hot-spot in NGC 2903. In IC 342, NGC 2146, and NGC 6764, the CO-13 J = 2 to 1 line is subthermally populated, implying gas densities less than or equal to 10(exp 4) cm(-3).

  20. Nickel-Catalyzed Highly Regioselective Hydrocyanation of Terminal Alkynes with Zn(CN)2 Using Water as the Hydrogen Source.

    PubMed

    Zhang, Xingjie; Xie, Xin; Liu, Yuanhong

    2018-06-08

    The first efficient and general nickel-catalyzed hydrocyanation of terminal alkynes with Zn(CN) 2 in the presence of water has been developed. The reaction provides a regioselective protocol for the synthesis of functionalized vinyl nitriles with a range of structural diversity under mild reaction conditions while obviating use of the volatile and hazardous reagent of HCN. Deuterium-labeling experiments confirmed the role of water as the hydrogen source in this hydrocyanation reaction.