Highly Efficient Performance and Conversion Pathway of Photocatalytic CH3SH Oxidation on Self-Stabilized Indirect Z-scheme g-C3N4/I3-BiOI.

Science.gov (United States)

Hu, Lingling; He, Huanjunwa; Xia, Dehua; Huang, Yajing; Xu, Jiarong; Li, Haoyue; He, Chun; Yang, Wenjing; Shu, Dong; Wong, Po Keung

2018-05-07

A self-stabilized Z-scheme porous g-C3N4/I3--containing BiOI ultrathin nanosheets (g-C3N4/I3--BiOI) heterojunction photocatalyst with I3-/I- redox mediator was successfully synthesized by a facile solvothermal method coupling with light illumination. The structure and optical properties of g-C3N4/I3--BiOI composites were systematically characterized by means of XRD, SEM, TEM, FT-IR, XPS, N2 adsorption/desorption, UV-vis DRS, PL. The g-C3N4/I3--BiOI composites, with heterojunction between porous g-C3N4 and BiOI ultrathin nanosheets, were firstly applied for the photocatalytic elimination of ppm-leveled CH3SH under LED visible light illumination. The g-C3N4/I3--BiOI heterojunction with 10% g-C3N4 showed a dramatically enhanced photocatalytic activity in removal of CH3SH compared with pure BiOI and g-C3N4, due to its effective interfacial charge transfer and separation. The adsorption and photocatalytic oxidation of CH3SH over g-C3N4/I3--BiOI were deeply explored by in situ DRIFTS, and the intermediates and conversion pathways were elucidated and compared. Furthermore, on the basis of reactive species trapping, ESR and Mott-Schottky experiments, it was revealed that the responsible reactive species for catalytic CH3SH composotion were h+, ·O2- and 1O2, thus, the g-C3N4/I3--BiOI heterojunction followed an indirect all-solid state Z-scheme charge transfer mode with self-stabilized I3-/I- pairs as redox mediator, which could accelerate the separation of photo-generated charge and enhance the redox reaction power of charged carriers simultaneously.

Optical bio-sniffer for methyl mercaptan in halitosis.

Science.gov (United States)

Mitsubayashi, Kohji; Minamide, Takeshi; Otsuka, Kimio; Kudo, Hiroyuki; Saito, Hirokazu

2006-07-28

An optical bio-sniffer for methyl mercaptan (MM) one of major odorous chemicals in halitosis (bad breath) was constructed by immobilizing monoamine oxidase type A (MAO-A) onto a tip of a fiber optic oxygen sensor (od: 1.59 mm) with an oxygen sensitive ruthenium organic complex (excitation: 470 nm, fluorescent: 600 nm). A flow cell for circulating buffer solution was applied to rinse and clean the tip of the device like nasal mucosa. In order to amplify the bio-sniffer output, a substrate regeneration cycle caused by coupling MAO-A with l-ascorbic acid (AsA) as reducing reaction with reagent system was applied to the sensor system. After evaluating the sensor characteristics using a gas flow measurement system with a gas generator, the optical bio-sniffer was applied to expired gases from healthy male volunteers for halitosis analysis as a physiological application. The optical bio-sniffer was applied to detect the oxygen consumption induced by MAO-A enzymatic reaction (and AsA chemical reduction) with gaseous MM application. The bio-sniffer was calibrated against MM vapor from 8.7 to 11500 ppb with correlation coefficient of 0.977, including a MM threshold (200 ppb) of pathologic halitosis and the human sense of smell level 3.5 (10.0 ppb), with good gas-selectivity based on the MAO-A substrate specificity. As the result of the physiological application, the optical bio-sniffer could successfully monitor the MM level change in breath samples during daytime, which is consistent with the previously reported results.

Atmospheric Chemistry of CH3CH2OCH3

DEFF Research Database (Denmark)

Andersen, Mads Peter Sulbæk; Bjørn Svendsen, Sissel; Østerstrøm, Freja From

2017-01-01

The atmospheric chemistry of methyl ethyl ether, CH3CH2OCH3, was examined using FT-IR/relative-rate methods. Hydroxyl radical and chlorine atom rate coefficients of k(CH3CH2OCH3+OH) = (7.53 ± 2.86) × 10−12 cm3 molecule−1 s−1 and k(CH3CH2OCH3+Cl) = (2.35 ± 0.43) × 10−10 cm3 molecule−1 s−1 were...

The methyl rotational potentials of Ga(CH sub 3) sub 3 derived by neutron spectroscopy

CERN Document Server

Prager, M; Parker, S F; Desmedt, A; Lechner, R E

2002-01-01

High resolution neutron spectra of Ga(CH sub 3) sub 3 show tunnelling transitions between 4.5 and 19 mu eV. The spectrum can be explained within the single-particle model on the basis of the monoclinic C2/c (Z = 16) low temperature crystal structure of Ga(CH sub 3) sub 3 with six inequivalent methyl groups in the unit cell. The overlapping tunnelling lines prevent the extraction of temperature dependent linewidths which would allow us to assign the librational energies measured in the phonon density of states. Classical rotational motion is studied by quasielastic neutron scattering. Three activation energies could be extracted. Methyl librations, tunnelling energies and barrier heights are combined with consistent intensities into rotational potentials. Only the concerted application of all spectroscopic techniques yields a conclusive description.

DFT study on oxidation of HS(CH2) m SH ( m = 1-8) in oxidative desulfurization

Science.gov (United States)

Song, Y. Z.; Song, J. J.; Zhao, T. T.; Chen, C. Y.; He, M.; Du, J.

2016-06-01

Density functional theory was employed for calculation of HS(CH2) m SH ( m = 1-8) and its derivatives at B3LYP method at 6-31++g ( d, p) level. Using eigenvalues of LUMO and HOMO for HS(CH2) m SH, the standard electrode potentials were estimated by a stepwise multiple regression techniques (MLR), and obtained as E° = 1.500 + 7.167 × 10-3 HOMO-0.229 LUMO with high correlation coefficients of 0.973 and F values of 43.973.

Evidence of site-specific fragmentation on thioacetic acid, CH3C(O)SH, irradiated with synchrotron radiation around the S 2p and O 1s regions.

Science.gov (United States)

Erben, Mauricio F; Geronés, Mariana; Romano, Rosana M; Della Védova, Carlos O

2006-01-26

Site-specific fragmentations following S 2p and O 1s photoexcitation of thioacetic acid, CH3C(O)SH, have been studied by means of synchrotron radiation. Total ion yield (TIY) spectra were measured and multicoincidence techniques, which include photoelectron-photoion coincidence (PEPICO) and photoelectron-photoion-photoion coincidence (PEPIPICO) time-of-flight mass spectrometry, were applied. The equivalent-core approximation was employed in order to estimate ionization transition values, and the observed peaks were tentatively assigned. A site-specific fragmentation is moderately observed by comparing the mass spectra collected at resonant energies around the inner and shallow inner shell S 2p and O 1s ionization edges. Beside H+ ion, the most abundant ions observed at the S 2p edge excitation were CH3CO+, SH+, S+, and CH3+. At the O 1s region the large CH3CO+ fragment was depressed, and small CHx+ (x = 0, 1, 2, 3), S+, and SH+ fragments were dominant. The dissociation dynamic for the main ion-pair production has been discussed. Two- and three-body dissociation channels have been observed in the PEPIPICO spectra, and the dissociation mechanisms were proposed.

Methylation of food commodities during fumigation with methyl bromide

International Nuclear Information System (INIS)

Starratt, A.N.; Bond, E.J.

1990-01-01

Sites of methylation in several commodities (wheat, oatmeal, peanuts, almonds, apples, oranges, maize, alfalfa and potatoes) during fumigation with 14 C-methyl bromide were studied. Differences were observed in levels of the major volatiles: methanol, dimethyl sulphide and methyl mercaptan, products of O- and S-methylation, resulting from treatment of the fumigated materials with 1N sodium hydroxide. In studies of maize and wheat, histidine was the amino acid which underwent the highest level of N-methylation. (author). 24 refs, 3 tabs

CH+ and SH+ in the diffuse interstellar medium: Tracers of turbulent dissipation

International Nuclear Information System (INIS)

Edith, Falgarone; Maryvonne, Gerin; Massimo, De Luca; Benjamin, Godard

2015-01-01

Absorption spectroscopy performed with Herschel/HIFI against the dust continuum emission of bright galactic star-forming regions has allowed the detection of the ground-state transitions of several hydride cations, CH + , OH + , H 2 O + , and SH + in the intervening diffuse medium. These hydrides, that need H 2 to form but are also destroyed by H 2 , appear to be most sensitive tracers of a poorly known component of the interstellar medium (ISM): molecular gas weakly shielded from UV radiation. Among them, because their formation routes are so highly endoenergic, the CH + and SH + cations are proposed to be specific tracers of turbulent dissipation occurring in diffuse gas. Their elusive origin in the diffuse ISM is therefore much more than a chemical riddle: it is rooted in the physics of the diffuse ISM, its turbulent dissipation rate and connects with the far broader issue of galaxy evolution. The Herschel/HIFI observations of CH + and SH + are compared with the predictions of chemical models that include the non-equilibrium effects of turbulent dissipation

Biodegradation tests of mercaptocarboxylic acids, their esters, related divalent sulfur compounds and mercaptans.

Science.gov (United States)

Rücker, Christoph; Mahmoud, Waleed M M; Schwartz, Dirk; Kümmerer, Klaus

2018-04-17

Mercaptocarboxylic acids and their esters, a class of difunctional compounds bearing both a mercapto and a carboxylic acid or ester functional group, are industrial chemicals of potential environmental concern. Biodegradation of such compounds was systematically investigated here, both by literature search and by experiments (Closed Bottle Test OECD 301D and Manometric Respirometry Test OECD 301F). These compounds were found either readily biodegradable or at least biodegradable to a significant extent. Some related compounds of divalent sulfur were tested for comparison (mercaptans, sulfides, disulfides). For the two relevant monofunctional compound classes, carboxylic acids/esters and mercaptans, literature data were compiled, and by comparison with structurally similar compounds without these functional groups, the influence of COOH/COOR' and SH groups on biodegradability was evaluated. Thereby, an existing rule of thumb for biodegradation of carboxylic acids/esters was supported by experimental data, and a rule of thumb could be formulated for mercaptans. Concurrent to biodegradation, abiotic processes were observed in the experiments, rapid oxidative formation of disulfides (dimerisation of monomercaptans and cyclisation of dimercaptans) and hydrolysis of esters. Some problems that compromise the reproducibility of biodegradation test results were discussed.

Structural/surface characterization and catalytic evaluation of rare-earth (Y, Sm and La) doped ceria composite oxides for CH{sub 3}SH catalytic decomposition

Energy Technology Data Exchange (ETDEWEB)

He, Dedong; Chen, Dingkai; Hao, Husheng; Yu, Jie; Liu, Jiangping; Lu, Jichang; Liu, Feng [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500 (China); Wan, Gengping [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500 (China); Research Center for Analysis and Measurement, Hainan University, Haikou, 570228 (China); He, Sufang [Research Center for Analysis and Measurement, Kunming University of Science and Technology, Kunming, 650093 (China); Luo, Yongming, E-mail: environcatalysis222@yahoo.com [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500 (China)

2016-12-30

Highlights: • Ce{sub 0.75}RE{sub 0.25}O{sub 2-δ} (RE = Y, Sm and La) were synthesized by citrate complexation method. • Ce{sub 0.75}Y{sub 0.25}O{sub 2-δ} exhibited the best stability for the decomposition of CH{sub 3}SH. • Cation radius played a key role in determining structure and surface characteristics. • Catalytic behavior depended on synergistic role of oxygen vacancies and basic sites. • Ce{sub 2}S{sub 3} accumulation on the surface was responsible for the deactivation of catalyst. - Abstract: A series of rare earth (Y, Sm and La) doped ceria composite oxides and pure CeO{sub 2} were synthesized and evaluated by conducting CH{sub 3}SH catalytic decomposition test. Several characterization studies, including XRD, BET, Raman, H{sub 2}-TPR, XPS, FT-IR, CO{sub 2}-TPD and CH{sub 3}SH-TPD, were undertaken to correlate structural and surface properties of the obtained ceria-based catalysts with their catalytic performance for CH{sub 3}SH decomposition. More oxygen vacancies and increased basic sites exhibited in the rare earth doped ceria catalysts. Y doped ceria sample (Ce{sub 0.75}Y{sub 0.25}O{sub 2-δ}), with a moderate increase in basic sites, contained more oxygen vacancies. More structural defects and active sites could be provided, and a relatively small amount of sulfur would accumulate, which resulted in better catalytic performance. The developed catalyst presented good catalytic behavior with stability very similar to that of typical zeolite-based catalysts reported previously. However, La doped ceria catalyst (Ce{sub 0.75}La{sub 0.25}O{sub 2-δ}) with the highest alkalinity was not the most active one. More sulfur species would be adsorbed and a large amount of cerium sulfide species (Ce{sub 2}S{sub 3}) would accumulate, which caused deactivation of the catalysts. The combined effect of increased oxygen vacancies and alkalinity led to the catalytic stability of Ce{sub 0.75}Sm{sub 0.25}O{sub 2-δ} sample was comparable to that of pure Ce

Contrast between the mechanisms for dissociative electron attachment to CH3SCN and CH3NCS

Science.gov (United States)

Miller, Thomas M.; Viggiano, Albert A.; Shuman, Nicholas S.

2018-05-01

The kinetics of thermal electron attachment to methyl thiocyanate (CH3SCN), methyl isothiocyanate (CH3NCS), and ethyl thiocyanate (C2H5SCN) were measured using flowing afterglow-Langmuir probe apparatuses at temperatures between 300 and 1000 K. CH3SCN and C2H5SCN undergo inefficient dissociative attachment to yield primarily SCN- at 300 K (k = 2 × 10-10 cm3 s-1), with increasing efficiency as temperature increases. The increase is well described by activation energies of 0.17 eV (CH3SCN) and 0.14 eV (C2H5SCN). CN- product is formed at product but at a rate at 300 K that is below our detection threshold (k differentiating the two mechanisms. The kinetic modeling reproduces the CH3NCS data only if dissociation through the transient anion is considered.

Conventional (CH) vs. stapled hemorrhoidectomy (SH) in surgical treatment of hemorrhoids. Ten years experience.

Science.gov (United States)

Manfredelli, Simone; Montalto, Gioacchino; Leonetti, Giovanni; Covotta, Marco; Amatucci, Chiara; Covotta, Alfredo; Forte, Angelo

2012-01-01

Interest about hemorrhoids is related to its high incidence and elevated social costs that derive from its treatment. Several comparative studies are reported in Literature to define a standard for ideal treatment of hemorrhoidal disease. Radical surgery is the only therapeutic option in case of III and IV stage haemorrhoids. Hemorrhoids surgical techniques are classified as Open, Closed and Stapled ones. We report our decennial experience on surgical treatment focusing on early, middle and late complications, indications and contraindications, satisfaction level of each surgical procedure for hemorrhoids. Four hundred forty-eight patients have been hospitalized in our department fom 1st January to 31st December 2008. Of these 241 underwent surgery with traditional open or closed technique and 207 with the SH technique according to Longo. This retrospective study includes only patients with symptomatic hemorrhoids at III or IV stage. There were no differences between CH and SH about both pre and post surgery hospitalization and intraoperative length. Pain is the most frequently observed early complication with a statistically significant difference in favour of SH. We obtain good results in CH group using anoderma sparing and perianal anaesthetic infiltration at the end of the surgery. In all cases, pain relief was obtained only with standard analgesic drugs (NSAIDs). We also observed that pain level influences the outcome after surgical treatment. No chronic pain cases were observed in both groups. Bleeding is another relevant early complication in particular after SH: we reported 2 cases of immediate surgical reintenvention and 2 cases treated with blood transfusion. Only in SH group we report also 5 cases of thrombosis of external haemorrhoids and 7 perianal hematoma both solved with medical therapy There were no statistical significant differences between two groups about fever, incontinence to flatus, urinary retention, fecal incontinence, substenosis and anal

Acid-base properties of 1-methyl-1,4-dilhydroborabenzene, CH3BC5H6

International Nuclear Information System (INIS)

Sullivan, S.A.; Sandford, H.; Beauchamp, J.L.; Ashe, A.J. III

1978-01-01

Ion cyclotron resonance techniques are employed to determine the gas-phase Bronsted and Lewis acidities as well as the Bronsted basicity of 1-methyl-1,4-dihydroborabenzene, CH 3 BC 5 H 6 . The ring proton is found to be highly acidic with PA(CH 3 BC 5 H 5 - ) = 337 +- 3 kcal/mol. This acidity results from the formation of 6π electron aromatic anion CH 3 BC 5 H 5 - , which is isoelectronic with toluene. Both the Lewis acidity toward F - as a reference base and the proton basicity of the parent molecule suggest that there is little interaction between the diene π system and the electron-deficient boron. This is further confirmed by the similarity of both negative and positive ion chemistry of the borabenzene to that of aliphatic boranes

Roles of the SH2 and SH3 domains in the regulation of neuronal Src kinase functions.

Science.gov (United States)

Groveman, Bradley R; Xue, Sheng; Marin, Vedrana; Xu, Jindong; Ali, Mohammad K; Bienkiewicz, Ewa A; Yu, Xian-Min

2011-02-01

Previous studies demonstrated that intra-domain interactions between Src family kinases (SFKs), stabilized by binding of the phosphorylated C-terminus to the SH2 domain and/or binding of the SH2 kinase linker to the SH3 domain, lock the molecules in a closed conformation, disrupt the kinase active site, and inactivate SFKs. Here we report that the up-regulation of N-methyl-D-aspartate receptors (NMDARs) induced by expression of constitutively active neuronal Src (n-Src), in which the C-terminus tyrosine is mutated to phenylalanine (n-Src/Y535F), is significantly reduced by dysfunctions of the SH2 and/or SH3 domains of the protein. Furthermore, we found that dysfunctions of SH2 and/or SH3 domains reduce auto-phosphorylation of the kinase activation loop, depress kinase activity, and decrease NMDAR phosphorylation. The SH2 domain plays a greater regulatory role than the SH3 domain. Our data also show that n-Src binds directly to the C-terminus of the NMDAR NR2A subunit in vitro, with a K(D) of 108.2 ± 13.3 nM. This binding is not Src kinase activity-dependent, and dysfunctions of the SH2 and/or SH3 domains do not significantly affect the binding. These data indicate that the SH2 and SH3 domains may function to promote the catalytic activity of active n-Src, which is important in the regulation of NMDAR functions. © 2010 The Authors Journal compilation © 2010 FEBS.

SH2/SH3 signaling proteins.

Science.gov (United States)

Schlessinger, J

1994-02-01

SH2 and SH3 domains are small protein modules that mediate protein-protein interactions in signal transduction pathways that are activated by protein tyrosine kinases. SH2 domains bind to short phosphotyrosine-containing sequences in growth factor receptors and other phosphoproteins. SH3 domains bind to target proteins through sequences containing proline and hydrophobic amino acids. SH2 and SH3 domain containing proteins, such as Grb2 and phospholipase C gamma, utilize these modules in order to link receptor and cytoplasmic protein tyrosine kinases to the Ras signaling pathway and to phosphatidylinositol hydrolysis, respectively. The three-dimensional structures of several SH2 and SH3 domains have been determined by NMR and X-ray crystallography, and the molecular basis of their specificity is beginning to be unveiled.

Effects of mercaptans and disulfides on photochemical and high energy radiation induced reactions. Progress report, November 1, 1974--October 31, 1975

International Nuclear Information System (INIS)

Cohen, S.G.

1975-10-01

A chain reaction may be formulated at alkaline pH in terms of e - /sub aq/ acting as a source of - OH as a reactant and H. regenerating e - /sub aq/. This may account for radiolytic conversion of CO to formate with high G. 60 Co γ-radiolysis of alkaline aqueous acetonitrile and acetamide gave no evidence of a chain; extensive hydrolysis of methyl acetate is now attributed to non-radiolytic, normal hydrolysis. Aromatic mercaptans are found to retard photoreduction of a benzophenone by aliphatic amines, largely by hydrogen atom-transfer repair reactions. Aliphatic mercaptans accelerate photoreduction, apparently by affecting the reduction to quenching ratio in the intermediate charge-transfer complex. In photoreduction of a benzophenone by 2,3-butylene glycol at pH 3, the glycol is converted, not to 3-hydroxy-2-butanone, but to 2-butanone, and about 4 molecules of this are formed per molecule of ketone reduced. A short chain appears to be established. Mercaptan appears to accelerate the reduction of the ketone and retard the formation of 2-butanone

CH{sup +} and SH{sup +} in the diffuse interstellar medium: Tracers of turbulent dissipation

Energy Technology Data Exchange (ETDEWEB)

Edith, Falgarone; Maryvonne, Gerin; Massimo, De Luca [Observatoire de Paris and Ecole Normale Supérieure, Paris (France); Benjamin, Godard [Centro de Astrobiologia, CSIC-INTA, Madrid (Spain)

2015-01-22

Absorption spectroscopy performed with Herschel/HIFI against the dust continuum emission of bright galactic star-forming regions has allowed the detection of the ground-state transitions of several hydride cations, CH{sup +}, OH{sup +}, H{sub 2}O{sup +}, and SH{sup +} in the intervening diffuse medium. These hydrides, that need H{sub 2} to form but are also destroyed by H{sub 2}, appear to be most sensitive tracers of a poorly known component of the interstellar medium (ISM): molecular gas weakly shielded from UV radiation. Among them, because their formation routes are so highly endoenergic, the CH{sup +} and SH{sup +} cations are proposed to be specific tracers of turbulent dissipation occurring in diffuse gas. Their elusive origin in the diffuse ISM is therefore much more than a chemical riddle: it is rooted in the physics of the diffuse ISM, its turbulent dissipation rate and connects with the far broader issue of galaxy evolution. The Herschel/HIFI observations of CH{sup +} and SH{sup +} are compared with the predictions of chemical models that include the non-equilibrium effects of turbulent dissipation.

Coupled-cluster sum-frequency generation nonlinear susceptibilities of methyl (CH3) and methylene (CH2) groups.

Science.gov (United States)

Tetsassi Feugmo, Conrard Giresse; Liégeois, Vincent; Champagne, Benoît

2017-11-15

The first vibrational sum frequency generation (SFG) spectra based on molecular properties calculated at the coupled cluster singles and doubles (CCSD) level of approximation have been simulated for interfacial model alkyl chains, providing benchmark data for comparisons with approximate methods, including density functional theory (DFT). The approach proceeds in three steps. In the first two steps, the molecular spectral properties are determined: the vibrational normal modes and frequencies and then the derivatives of the dipole moment and of the polarizability with respect to the normal coordinates. These derivatives are evaluated with a numerical differentiation approach, of which the accuracy was monitored using Romberg's procedure. Then, in the last step, a three-layer model is employed to evaluate the macroscopic second-order nonlinear optical responses and thereby the simulated SFG spectra of the alkyl interface. Results emphasize the following facts: (i) the dipole and polarizability derivatives calculated at the DFT level with the B3LYP exchange-correlation functional can differ, with respect to CCSD, by as much as ±10 to 20% and ±20 to 50% for the CH 3 and CH 2 vibrations, respectively; (ii) these differences are enhanced when considering the SFG intensities as well as their variations as a function of the experimental configuration (ppp versus ssp) and as a function of the tilt and rotation angles, defining the orientation of the alkyl chain at the interface; (iii) these differences originate from both the vibrational normal coordinates and the Cartesian derivatives of the dipole moment and polarizability; (iv) freezing the successive fragments of the alkyl chain strongly modifies the SFG spectrum and enables highlighting the delocalization effects between the terminal CH 3 group and its neighboring CH 2 units; and finally (v) going from the free chain to the free methyl model, and further to C 3v constraints on leads to large variations of two ratios

Microwave spectroscopy of HCOO13CH3 in the second methyl torsional excited state

Science.gov (United States)

Kobayashi, Kaori; Kuwahara, Takuro; Tachi, Haruka; Urata, Yuki; Tsunekawa, Shozo; Hayashi, Naoto; Higuchi, Hiroyuki; Fujitake, Masaharu; Ohashi, Nobukimi

2018-01-01

The new experimental results and analysis of the microwave spectra of HCOO13CH3 in the second methyl torsional excited state are reported. Pseudo-principal axis method (pseudo-PAM) was successfully applied to the normal methyl formate in the second torsional excited state and again applied to this isotopologue. We succeeded to assign 536 A-species transitions up to J = 33 and Ka = 15 and 417 E-species transitions up to J = 32 and Ka = 14. Thirty parameters were used to do the least-squares-analysis by using the pseudo-PAM Hamiltonian consisting of rotational, centrifugal distortion, and internal-rotational constants.

Vapor-Liquid Equilibrium Measurements and Modeling of the Propyl Mercaptan plus Methane plus Water System

DEFF Research Database (Denmark)

Awan, Javeed; Thomsen, Kaj; Coquelet, Christophe

2010-01-01

In this work, vapor−liquid equilibrium (VLE) measurements of propyl mercaptan (PM) in pure water were performed at three different temperatures, (303, 323, and 365) K, with a pressure variation from (1 to 8) MPa. The total system pressure was maintained by CH4. The inlet mole fraction of propyl...

Constraining the Molecular Complexity in the Interstellar Medium—The Formation of Ethyl Methyl Ether (CH3OCH2CH3) in Star-forming Regions

Science.gov (United States)

Bergantini, Alexandre; Frigge, Robert; Kaiser, Ralf I.

2018-05-01

We report the first confirmed synthesis of ethyl methyl ether (EME, CH3CH2OCH3) within astrophysical model ices containing water (H2O) and methane (CH4) exposed to ionizing radiation at ultra-low temperatures of 5 K. EME (also known as methoxyethane), was recently observed toward Orion KL and currently is the largest confirmed oxygen-bearing molecule found in the interstellar medium. Exploiting isomer-selective photoionization (PI) of the subliming molecules in the temperature-programmed desorption phase at 10.49, 9.92, and 9.70 eV, coupled with reflectron time-of-flight mass spectrometry and isotopic substitution experiments (H2 18O–CH4), the detection of fragment ions of EME at m/z = 45 (C2H5O+) and m/z = 59 (C3H7O+), and probing the proton transfer in subliming ethanol–EME complexes via m/z = 61 (C3H9O+), the present study reveals that EME can be formed from suprathermal reactions initiated by cosmic rays and secondary electrons generated within astrophysical ices. The detection of EME in our experiments represents a significant advance in the understanding of formation pathways of complex organic molecules present in hot cores and helps to constrain astrochemical models on the formation of such species within molecular clouds.

Kinetics of aerobic oxidation of volatile sulfur compounds in wastewater and biofilm from sewers

DEFF Research Database (Denmark)

Rudelle, Elise Alice; Vollertsen, Jes; Hvitved-Jacobsen, Thorkild

2013-01-01

Laboratory experiments were conducted to investigate the kinetics of aerobic chemical and biological oxidation of selected odorous volatile sulfur compounds (VSCs) by wastewater and biofilm from sewers. The VSCs included methyl mercaptan (MeSH), ethyl mercaptan (EtSH), dimethyl sulfide (DMS......-spot downstream of a force main and the other was a gravity sewer transporting young aerobic wastewater. The kinetics of VSC oxidation for both wastewater and suspended biofilm samples followed a first-order rate equation. The average values of the reaction rate constants demonstrated the following order...... in the aerobic wastewater....

Disproportionation and thermochemical sulfate reduction reactions in S-H20-Ch4 and S-D2O-CH4 systems from 200 to 340 °C at elevated pressures

Science.gov (United States)

Yuan, Shunda; Chou, I-Ming; Burruss, Robert A.

2013-01-01

Elemental sulfur, as a transient intermediate compound, by-product, or catalyst, plays significant roles in thermochemical sulfate reduction (TSR) reactions. However, the mechanisms of the reactions in S-H2O-hydrocarbons systems are not clear. To improve our understanding of reaction mechanisms, we conducted a series of experiments between 200 and 340 °C for S-H2O-CH4, S-D2O-CH4, and S-CH4-1m ZnBr2 systems in fused silica capillary capsules (FSCC). After a heating period ranging from 24 to 2160 hours (hrs), the quenched samples were analyzed by Raman spectroscopy. Combined with the in situ Raman spectra collected at high temperatures and pressures in the S-H2O and S-H2O-CH4 systems, our results showed that (1) the disproportionation of sulfur in the S-H2O-CH4 system occurred at temperatures above 200 °C and produced H2S, SO42-, and possibly trace amount of HSO4-; (2) sulfate (and bisulfate), in the presence of sulfur, can be reduced by methane between 250 and 340 °C to produce CO2 and H2S, and these TSR temperatures are much closer to those of the natural system (2O-CH4 system may take place simultaneously, with TSR being favored at higher temperatures; and (4) in the system S-D2O-CH4, both TSR and the competitive disproportionation reactions occurred simultaneously at temperatures above 300 °C, but these reactions were very slow at lower temperatures. Our observation of methane reaction at 250 °C in a laboratory time scale suggests that, in a geologic time scale, methane may be destroyed by TSR reactions at temperatures > 200 °C that can be reached by deep drilling for hydrocarbon resources.

Radiative forcing calculations for CH3Br

International Nuclear Information System (INIS)

Grossman, A.S.; Blass, W.E.; Wuebbles, D.J.

1995-06-01

Methyl Bromide, CH 3 Br, is the major organobromine species in the lower atmosphere and is a primary source of bromine in the stratosphere. It has a lifetime of 1.3 years. The IR methyl bromide spectra in the atmospheric window region, 7--13μ, was determined using a well tested Coriolis resonance and ell-doubling (and ell-resonance) computational system. A radiative forcing value of 0.00493 W/m 2 /ppbv was obtained for CH 3 Br and is approximately linear in the background abundance. This value is about 2 percent of the forcing of CFC-11 and about 278 times the forcing of C0 2 , on a per molecule basis. The radiative forcing calculation is used to estimate the global warming potential (GWP) of CH 3 Br. The results give GWPs for CH 3 Br of the order of 13 for an integration period of 20 years and 4 for an integration period of 100 years (assuming C0 2 = 1, following IPCC [1994]). While CH 3 Br has a GWP which is approximately 25 percent of the GWP of CH 4 , the current emission rates are too low to cause serious atmospheric greenhouse heating effects at this time

N-Methyl-D aspartate receptor-mediated effect on glucose transporter-3 levels of high glucose exposed-SH-SY5Y dopaminergic neurons.

Science.gov (United States)

Engin, Ayse Basak; Engin, Evren Doruk; Karakus, Resul; Aral, Arzu; Gulbahar, Ozlem; Engin, Atilla

2017-11-01

High glucose and insulin lead to neuronal insulin resistance. Glucose transport into the neurons is achieved by regulatory induction of surface glucose transporter-3 (GLUT3) instead of the insulin. N-methyl-D aspartate (NMDA) receptor activity increases GLUT3 expression. This study explored whether an endogenous NMDA receptor antagonist, kynurenic acid (KynA) affects the neuronal cell viability at high glucose concentrations. SH-SY5Y neuroblastoma cells were exposed to 150-250 mg/dL glucose and 40 μU/mL insulin. In KynA and N-nitro-l-arginine methyl ester (L-NAME) supplemented cultures, oxidative stress, mitochondrial metabolic activity (MTT), nitric oxide as nitrite+nitrate (NOx) and GLUT3 were determined at the end of 24 and 48-h incubation periods. Viable cells were counted by trypan blue dye. High glucose-exposed SH-SY5Y cells showed two-times more GLUT3 expression at second 24-h period. While GLUT3-stimulated glucose transport and oxidative stress was increased, total mitochondrial metabolic activity was significantly reduced. Insulin supplementation to high glucose decreased NOx synthesis and GLUT3 levels, in contrast oxidative stress increased three-fold. KynA significantly reduced oxidative stress, and increased MTT by regulating NOx production and GLUT3 expression. KynA is a noteworthy compound, as an endogenous, specific NMDA receptor antagonist; it significantly reduces oxidative stress, while increasing cell viability at high glucose and insulin concentrations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Plasmas pour la destruction de l'H2S et des mercaptans Plasmas for Destruction of H2s and Mercaptans

Directory of Open Access Journals (Sweden)

Czernichowski A.

2006-12-01

Full Text Available Cet article passe en revue l'utilisation des plasmas comme milieu activateurs d'une oxydation de H2S ou CH3SH dilués dans l'air, le CO2 ou la vapeur d'eau, à fins de conversion en SO, moins malodorant. Le produit peut être ensuite utilisé comme réactif dans un processus similaire à celui de Claus, en présence d'eau, ce qui permet de convertir deux fois plus de polluants initiaux en soufre élémentaire. Une attention particulière est portée aux décharges électriques glissantes (GlidArc. Ces décharges puissantes produisent un plasma non thermique qui active des réactions oxydatrices. La plupart des expériences ont été réalisées en utilisant les réacteurs GlidArc-I à un ou à quatre étages. Les sulfures dilués dans l'air dans des concentrations initiales atteignant jusqu'à 1 %( H2S ou 0,1 % (CH3SH ont été traités sous des flux jusqu'à 70 m3(n/h d'air pollué et sous une puissance de 5 kW. Les essais ont été réalisés sous 1 atm. Une dépollution jusqu'à 100 % a été obtenue moyennant un coût énergétique assez bas dépendant de la concentration initiale du polluant : environ 1000 kWh par kilogramme de soufre extrait pour 100 ppm de H2S et seulement 10 kWh/kg pour 1 % initial d'H2S dans l'air. Pratiquement les mêmes coûts ont été observés dans le cas de mélanges CH3SH-air. En utilisant une très simple douche en recirculation d'eau qui lave les gaz sortants (l'eau se sature avec le SO2 et capture ainsi l'H2S non traité nous avons divisé ces coûts d'énergie par trois, en évitant également l'émission de SO2, et en obtenant du soufre non toxique. Un nouveau principe (et réacteur GlidArc-II est ensuite présenté ; il s'agit d'une brosseà décharges électriques. Nos premiers tests sont très prometteurs car dès à présent, nous divisons déjà la dépense énergétique par deux par rapport au GlidArc-I. L'échelle industrielle peut par conséquent être envisagée. Plasmas are reviewed as activation

Computing energy levels of CH4, CHD3, CH3D, and CH3F with a direct product basis and coordinates based on the methyl subsystem.

Science.gov (United States)

Zhao, Zhiqiang; Chen, Jun; Zhang, Zhaojun; Zhang, Dong H; Wang, Xiao-Gang; Carrington, Tucker; Gatti, Fabien

2018-02-21

Quantum mechanical calculations of ro-vibrational energies of CH 4 , CHD 3 , CH 3 D, and CH 3 F were made with two different numerical approaches. Both use polyspherical coordinates. The computed energy levels agree, confirming the accuracy of the methods. In the first approach, for all the molecules, the coordinates are defined using three Radau vectors for the CH 3 subsystem and a Jacobi vector between the remaining atom and the centre of mass of CH 3 . Euler angles specifying the orientation of a frame attached to CH 3 with respect to a frame attached to the Jacobi vector are used as vibrational coordinates. A direct product potential-optimized discrete variable vibrational basis is used to build a Hamiltonian matrix. Ro-vibrational energies are computed using a re-started Arnoldi eigensolver. In the second approach, the coordinates are the spherical coordinates associated with four Radau vectors or three Radau vectors and a Jacobi vector, and the frame is an Eckart frame. Vibrational basis functions are products of contracted stretch and bend functions, and eigenvalues are computed with the Lanczos algorithm. For CH 4 , CHD 3 , and CH 3 D, we report the first J > 0 energy levels computed on the Wang-Carrington potential energy surface [X.-G. Wang and T. Carrington, J. Chem. Phys. 141(15), 154106 (2014)]. For CH 3 F, the potential energy surface of Zhao et al. [J. Chem. Phys. 144, 204302 (2016)] was used. All the results are in good agreement with experimental data.

Computing energy levels of CH4, CHD3, CH3D, and CH3F with a direct product basis and coordinates based on the methyl subsystem

Science.gov (United States)

Zhao, Zhiqiang; Chen, Jun; Zhang, Zhaojun; Zhang, Dong H.; Wang, Xiao-Gang; Carrington, Tucker; Gatti, Fabien

2018-02-01

Quantum mechanical calculations of ro-vibrational energies of CH4, CHD3, CH3D, and CH3F were made with two different numerical approaches. Both use polyspherical coordinates. The computed energy levels agree, confirming the accuracy of the methods. In the first approach, for all the molecules, the coordinates are defined using three Radau vectors for the CH3 subsystem and a Jacobi vector between the remaining atom and the centre of mass of CH3. Euler angles specifying the orientation of a frame attached to CH3 with respect to a frame attached to the Jacobi vector are used as vibrational coordinates. A direct product potential-optimized discrete variable vibrational basis is used to build a Hamiltonian matrix. Ro-vibrational energies are computed using a re-started Arnoldi eigensolver. In the second approach, the coordinates are the spherical coordinates associated with four Radau vectors or three Radau vectors and a Jacobi vector, and the frame is an Eckart frame. Vibrational basis functions are products of contracted stretch and bend functions, and eigenvalues are computed with the Lanczos algorithm. For CH4, CHD3, and CH3D, we report the first J > 0 energy levels computed on the Wang-Carrington potential energy surface [X.-G. Wang and T. Carrington, J. Chem. Phys. 141(15), 154106 (2014)]. For CH3F, the potential energy surface of Zhao et al. [J. Chem. Phys. 144, 204302 (2016)] was used. All the results are in good agreement with experimental data.

ChAMP: updated methylation analysis pipeline for Illumina BeadChips.

Science.gov (United States)

Tian, Yuan; Morris, Tiffany J; Webster, Amy P; Yang, Zhen; Beck, Stephan; Feber, Andrew; Teschendorff, Andrew E

2017-12-15

The Illumina Infinium HumanMethylationEPIC BeadChip is the new platform for high-throughput DNA methylation analysis, effectively doubling the coverage compared to the older 450 K array. Here we present a significantly updated and improved version of the Bioconductor package ChAMP, which can be used to analyze EPIC and 450k data. Many enhanced functionalities have been added, including correction for cell-type heterogeneity, network analysis and a series of interactive graphical user interfaces. ChAMP is a BioC package available from https://bioconductor.org/packages/release/bioc/html/ChAMP.html. a.teschendorff@ucl.ac.uk or s.beck@ucl.ac.uk or a.feber@ucl.ac.uk. Supplementary data are available at Bioinformatics online. © The Author(s) 2017. Published by Oxford University Press.

Action of Mercaptan and Disulfide in Hydrogen Atom Exchange Reactions; Action des Thioalcools et des Disulfures dans les Reactions d'Echange d'Atomes d'Hydrogene; Vozdejstvie merkaptanov i disul'fidov v reaktsiyakh obmena atoma vodoroda; Accion de los Mercaptanos y Disulfuros en las Reacciones de Intercambio del Hidrogeno Atomico

Energy Technology Data Exchange (ETDEWEB)

Cohen, S. G. [Brandeis University Waltham, MA (United States)

1965-10-15

Free- radical, photochemical, and high-energy radiation-induced reactions may be catalysed or inhibited by rapid hydrogen atom exchange reactions of mercaptans and disulfides. The radical-induced, light-initiated, and benzophenone-sensitized decarbonylations of aldehydes are catalysed by mercaptans. The chain-propagating hydrogen transfer reaction, R' + RCH = O -> RH + RC = O , is made more rapid by a similar sequence of hydrogen atom transfers involving the sulfur compound: R' + C{sub 6}H{sub 5}CH{sub 2}SH -> RH + C{sub 6}H{sub 5}CH{sub 2}S'; C{sub 6}H{sub 5}CH{sub 2}S + RCH = 0 -> C{sub 6}H{sub 5}CH{sub 2}SH + RC = 0. The photoreduction of benzophenone in 2-propanol leads to benzpinacol by a non-chain reaction via the radicals (C{sub 6}H{sub 5}){sub 2}C-OH and (CH{sub 3}){sub 2}COH. The reaction is retarded and inhibited by mercaptan and disulfide, which reconvert the radicals to the starting materials by rapid hydrogen transfer reactions and are themselves regenerated in their alternate valence states, each molecule of sulfur compound negating the chemical consequences of many quanta: (C{sub 6}H{sub 5}){sub 2}C-OH + AS' -> (C{sub 6}H{sub 5}){sub 2}C = O + ASH; (CH{sub 3}){sub 2}C-OH + ASH -> (CH{sub 3}){sub 2}C = 0 + AS'. Proof of the mechanism is found in: equilibration of initially present mercaptan or disulfide during inhibition; in racemization of optically active alcohol during inhibition; in deuterium exchange during inhibition. Similar inhibition is seen when only one intermediate radical is formed, as in the benzophenone- benzhydrol and acetophenone-{alpha}-methyl-benzyl alcohol systems. Inhibition by sulfur compounds, by the same mechanism, is found in the {sup 60}Co {gamma}-ray induced conversion of benzophenone to benzpinacol; naphthalene has no protecting effect on benzophenone in the {sup 60}Co system, while quenching the photochemical reaction. The protection by sulfur compounds of solutes against radiation damage thus results from hydrogen atom

Thermal Decomposition of Potential Ester Biofuels. Part I: Methyl Acetate and Methyl Butanoate

Energy Technology Data Exchange (ETDEWEB)

Porterfield, Jessica P.; Bross, David H.; Ruscic, Branko; Thorpe, James H.; Nguyen, Thanh Lam; Baraban, Joshua H.; Stanton, John F.; Daily, John W.; Ellison, G. Barney

2017-06-09

Two methyl esters have been examined as models for the pyrolysis of biofuels. Dilute samples (0.06 - 0.13%) of methyl acetate (CH₃COOCH₃) and methyl butanoate (CH₃CH₂CH₂COOCH₃) were entrained in (He, Ar) carrier gas and decomposed in a set of flash-pyrolysis micro-reactors. The pyrolysis products resulting from the methyl esters were detected and identified by vacuum ultraviolet photoionization mass spectrometry. Complementary product identification was provided by matrix infrared absorption spectroscopy. Pyrolysis pressures in the pulsed micro-reactor were roughly 20 Torr and residence times through the reactors were approximately 25 - 150 µs. Reactor temperatures of 300 – 1600 K were explored. Decomposition of CH₃COOCH₃ commences at 1000 K and the initial products are (CH₂=C=O and CH₃OH). As the micro-reactor is heated to 1300 K, a mixture of (CH₂=C=O and CH₃OH, CH₃, CH₂=O, H, CO, CO₂) appears. The thermal cracking of CH₃CH₂CH₂COOCH₃ begins at 800 K with the formation of (CH₃CH₂CH=C=O, CH₃OH). By 1300 K, the pyrolysis of methyl butanoate yields a complex mixture of (CH₃CH₂CH=C=O, CH₃OH, CH₃, CH₂=O, CO, CO₂, CH₃CH=CH₂, CH₂CHCH₂, CH₂=C=CH₂, HCCCH₂, CH₂=C=C=O, CH₂=CH₂, HCΞCH, CH₂=C=O). Based on the results from the thermal cracking of methyl acetate and methyl butanoate, we predict several important decomposition channels for the pyrolysis of fatty acid methyl esters, R CH₂-COOCH₃. The lowest energy fragmentation will be a 4-center elimination of methanol to form the ketene, RCH=C=O. At higher temperatures, concerted

Rate Coefficient Measurements of the Reaction CH3 + O2 = CH3O + O

Science.gov (United States)

Hwang, S. M.; Ryu, Si-Ok; DeWitt, K. J.; Rabinowitz, M. J.

1999-01-01

Rate coefficients for the reaction CH3 + O2 = CH3O + O were measured behind reflected shock waves in a series of lean CH4-O2-Ar mixtures using hydroxyl and methyl radical diagnostics. The rate coefficients are well represented by an Arrhenius expression given as k = (1.60(sup +0.67, sub -0.47 ) x 10(exp 13) e(-15813 +/- 587 K/T)/cubic cm.mol.s. This expression, which is valid in the temperature range 1575-1822 K, supports the downward trend in the rate coefficients that has been reported in recent determinations. All measurements to date, including the present study, have been to some extent affected by secondary reactions. The complications due to secondary reactions, choice of thermochemical data, and shock-boundary layer interactions that affect the determination of the rate coefficients are examined.

Rate Coefficient Measurements of the Reaction CH3+O2+CH3O+O

Science.gov (United States)

Hwang, S. M.; Ryu, Si-Ok; DeWitt, K. J.; Rabinowitz, M. J.

1999-01-01

Rate coefficients for the reaction CH3 + O2 = CH3O + O were measured behind reflected shock waves in a series of lean CH4-O2-Ar mixtures using hydroxyl and methyl radical diagnostics. The rate coefficients are well represented by an Arrhenius expression given as k = (1.60(sup +0.67, -0.47)) X 10(exp 13) exp(- 15813 +/- 587 K/T)cc/mol s. This expression, which is valid in the temperature range 1575-1822 K, supports the downward trend in the rate coefficients that has been reported in recent determinations. All measurements to date, including the present study, have been to some extent affected by secondary reactions. The complications due to secondary reactions, choice of thermochemical data, and shock-boundary layer interactions that affect the determination of the rate coefficients are examined.

Crystal structure of the Src family kinase Hck SH3-SH2 linker regulatory region supports an SH3-dominant activation mechanism.

Science.gov (United States)

Alvarado, John J; Betts, Laurie; Moroco, Jamie A; Smithgall, Thomas E; Yeh, Joanne I

2010-11-12

Most mammalian cell types depend on multiple Src family kinases (SFKs) to regulate diverse signaling pathways. Strict control of SFK activity is essential for normal cellular function, and loss of kinase regulation contributes to several forms of cancer and other diseases. Previous x-ray crystal structures of the SFKs c-Src and Hck revealed that intramolecular association of their Src homology (SH) 3 domains and SH2 kinase linker regions has a key role in down-regulation of kinase activity. However, the amino acid sequence of the Hck linker represents a suboptimal ligand for the isolated SH3 domain, suggesting that it may form the polyproline type II helical conformation required for SH3 docking only in the context of the intact structure. To test this hypothesis directly, we determined the crystal structure of a truncated Hck protein consisting of the SH2 and SH3 domains plus the linker. Despite the absence of the kinase domain, the structures and relative orientations of the SH2 and SH3 domains in this shorter protein were very similar to those observed in near full-length, down-regulated Hck. However, the SH2 kinase linker adopted a modified topology and failed to engage the SH3 domain. This new structure supports the idea that these noncatalytic regions work together as a "conformational switch" that modulates kinase activity in a manner unique to the SH3 domain and linker topologies present in the intact Hck protein. Our results also provide fresh structural insight into the facile induction of Hck activity by HIV-1 Nef and other Hck SH3 domain binding proteins and implicate the existence of innate conformational states unique to individual Src family members that "fine-tune" their sensitivities to activation by SH3-based ligands.

Synthesis of ethyl [14CH3]methylmalonyl thioglycolate as a possible substrate analogue of [14CH3]methylmalonyl coenzyme-A

International Nuclear Information System (INIS)

Kovacs, I.; Kovacs, Z.

1991-01-01

Ethyl methylmalonyl thioglycolate is a potential substrate analogue of methylmalonyl-coenzyme-A (methylmalonyl-CoA) in the investigation of propionic acid metabolism. To prove this hypothesis, the tracer ethyl [ 14 CH 3 ] methylmalonyl thioglycolate was synthesized via methyl-Meldrum's acid to carry out the biochemical examinations. The method described can also be used to synthesize [ 14 CH 3 ] methylmalonyl-CoA by transesterification of active labelled methylmalonyl thiophenyl ester. This latter intermediate is chemically stable when stored at room temperature, and the unstable [ 14 CH 3 ]methylmalonyl-CoA can be prepared in one step just preceeding the biochemical experiments. (author)

[Analysis of volatile sulfur compounds production of oral cavity in preschool children and influencing factors].

Science.gov (United States)

Zhang, Qun; Liu, Xue-nan; Chang, Qing; Ao, Shuang; Zheng, Shu-guo; Xu, Tao

2015-12-18

To investigate the prevalence of volatile sulfur compounds(VSC) in oral cavity of preschool children, and to analyze related factors, thus to provide scientific basis for the prediction and treatment of halitosis. The VSC content (hydrogen sulfide, methyl mercaptan, dimethyl sulfide) of 170 preschool children (4 to 6 years old) was detected by a portable gas chromatograph OralChromaTM. The status of the oral health was evaluated. The living habits and other aspects were obtained through questionnaires from the children's parents. A soft package for social statistics version 13.0 (SPSS 13.0) was used in which univariate analysis and multivariate analysis were utilized to analyze the related factors of halitosis in children. In the study, 34.4% of the total subjects had excessive VSC. Hydrogen sulfide (H₂S) [(1.59 ± 2.41) ng/10 mL] and total VSC concentration [(2.14 ± 4.42) ng/10 mL] in the girls were significantly higher (P<0.05) than those in the boys. The tongue coating score had a significant positive correlation with H2S [tongue coating area (1.68 ± 2.48) ng/10 mL,tongue coating thickness (2.18 ± 2.69) ng/10 mL] and total VSC concentration [tongue coating area, (2.26 ± 4.31) ng/10 mL,tongue coating thickness (2.41 ± 3.02) ng/10 mL , P<0.01]. The site number of DI-S ≥ 2 had a significant positive correlation with methyl mercaptan (CH3SH) and dimethyl sulfide [(CH3)2S] concentration (P<0.01). The concentration of H₂S [(1.19 ± 1.62) ng/10 mL] in children, whose mother had a higher degree of education, was statistically lower (P<0.01). The children who took dessert or sweat drinks more frequently had lower H2S [(1.04 ± 1.55) ng/10 mL, P<0.05] concentration, while CH3SH and (CH3₂)S concentration [(0.29 ± 1.92) ng/10 mL, (0.37 ± 2.06) ng/10 mL, P<0.05) were higher in the children with mouth-breath habit. A high prevalence of halitosis was noted in preschool children. Gender, tongue coating index, debris index-simplified, status of the mother

Comparison of SH3 and SH2 domain dynamics when expressed alone or in an SH(3+2) construct: the role of protein dynamics in functional regulation.

Science.gov (United States)

Engen, J R; Smithgall, T E; Gmeiner, W H; Smith, D L

1999-04-02

Protein dynamics play an important role in protein function and regulation of enzymatic activity. To determine how additional interactions with surrounding structure affects local protein dynamics, we have used hydrogen exchange and mass spectrometry to investigate the SH2 and SH3 domains of the protein tyrosine kinase Hck. Exchange rates of isolated Hck SH3 and SH2 domains were compared with rates for the same domains when part of a larger SH(3+2) construct. Increased deuterium incorporation was observed for the SH3 domain in the joint construct, particularly near the SH2 interface and the short sequence that connects SH3 to SH2, implying greater flexibility of SH3 when it is part of SH(3+2). Slow cooperative unfolding of the SH3 domain occurred at the same rate in isolated SH3 as in the SH(3+2) construct, suggesting a functional significance for this unfolding. The SH2 domain displayed relatively smaller changes in flexibility when part of the SH(3+2) construct. These results suggest that the domains influence each other. Further, our results imply a link between functional regulation and structural dynamics of SH3 and SH2 domains. Copyright 1999 Academic Press.

Visible absorption spectrum of the CH3CO radical.

Science.gov (United States)

Rajakumar, B; Flad, Jonathan E; Gierczak, Tomasz; Ravishankara, A R; Burkholder, James B

2007-09-20

The visible absorption spectrum of the acetyl radical, CH(3)CO, was measured between 490 and 660 nm at 298 K using cavity ring-down spectroscopy. Gas-phase CH(3)CO radicals were produced using several methods including: (1) 248 nm pulsed laser photolysis of acetone (CH(3)C(O)CH(3)), methyl ethyl ketone (MEK, CH(3)C(O)CH(2)CH(3)), and biacetyl (CH(3)C(O)C(O)CH(3)), (2) Cl + CH(3)C(O)H --> CH(3)C(O) + HCl with Cl atoms produced via pulsed laser photolysis or in a discharge flow tube, and (3) OH + CH(3)C(O)H --> CH(3)CO + H(2)O with two different pulsed laser photolysis sources of OH radicals. The CH(3)CO absorption spectrum was assigned on the basis of the consistency of the spectra obtained from the different CH(3)CO sources and agreement of the measured rate coefficients for the reaction of the absorbing species with O(2) and O(3) with literature values for the CH(3)CO + O(2) + M and CH(3)CO + O(3) reactions. The CH(3)CO absorption spectrum between 490 and 660 nm has a broad peak centered near 535 nm and shows no discernible structure. The absorption cross section of CH(3)CO at 532 nm was measured to be (1.1 +/- 0.2) x 10(-19) cm(2) molecule(-1) (base e).

CH3-ReO3 on gamma-Al2O3: understanding its structure, initiation,and reactivity in olefin metathesis

Energy Technology Data Exchange (ETDEWEB)

Salameh, Alain; Joubert, Jerome; Baudouin, Anne; Lukens, Wayne; Delbecq, Francoise; Sautet, Philippe; Basset, Jean Marie; Coperet,Christophe

2007-01-20

Me-ReO3 on gamma-alumina: understanding the structure, theinitiation and thereactivity of a highly active olefin metathesiscatalyst Heterolytic splitting of the C-H bond of the methyl group ofCH3ReO3 on AlsO reactive sites of alumina as a way to generate the activesite of CH3ReO3 supported on gamma-Al203.

Radiative forcing calculations for CH3Cl

International Nuclear Information System (INIS)

Grossman, A.S.; Grant, K.E.; Wuebbles, D.J.

1994-06-01

Methyl chloride, CH 3 Cl, is the major natural source of chlorine to the stratosphere. The production of CH 3 Cl is dominated by biological sources from the oceans and biomass burning. Production has a seasonal cycle which couples with the short lifetime of tropospheric CH 3 Cl to produce nonuniform global mixing. As an absorber of infrared radiation, CH 3 Cl is of interest for its potential affect on the tropospheric energy balance as well as for its chemical interactions. In this study, we estimate the radiative forcing and global warming potential (GWP) of CH 3 Cl. Our calculations use an infrared radiative transfer model based on the correlated k-distribution algorithm for band absorption. Global and annual average vertical profiles of temperature and trace gas concentration were assumed. The effects of clouds are modeled using three layers of global and annual average cloud optical properties. A radiative forcing value of 0.0053 W/m 2 ppbv was obtained for CH 3 Cl and is approximately linear in the background abundance. This value is about 2 percent of the forcing of CFC-11 and about 300 times the forcing of CO 2 , on a per molecule basis. The radiative forcing calculation for CH 3 Cl is used to estimate the global warming potential (GWP) of CH 3 Cl. The results give GWPs for CH 3 Cl of the order of 25 at a time of 20 years(CO 2 = 1). This result indicates that CH 3 Cl has the potential to be a major greenhouse gas if significant human related emissions were introduced into the atmosphere

Chemical shift assignments of the partially deuterated Fyn SH2-SH3 domain.

Science.gov (United States)

Kieken, Fabien; Loth, Karine; van Nuland, Nico; Tompa, Peter; Lenaerts, Tom

2018-04-01

Src Homology 2 and 3 (SH2 and SH3) are two key protein interaction modules involved in regulating the activity of many proteins such as tyrosine kinases and phosphatases by respective recognition of phosphotyrosine and proline-rich regions. In the Src family kinases, the inactive state of the protein is the direct result of the interaction of the SH2 and the SH3 domain with intra-molecular regions, leading to a closed structure incompetent with substrate modification. Here, we report the 1 H, 15 N and 13 C backbone- and side-chain chemical shift assignments of the partially deuterated Fyn SH3-SH2 domain and structural differences between tandem and single domains. The BMRB accession number is 27165.

Enzymatic studies on the metabolism of the tetrahydrofurfuryl mercaptan moiety of thiamine tetrahydrofurfuryl disulfide, 2

International Nuclear Information System (INIS)

Fujita, Takeshi; Suzuoki, Ziro; Kozuka, Seizi; Oae, Shigeru.

1973-01-01

The second step in the enzymatic process responsible for the novel metabolic pathway of foreign mercaptans leading to methylsulfonyl metabolites was shown to be sulfoxidation, subsequent to S-methylation. By using [ 35 S] methyl tetrahydrofurfuryl sulfide (MTFS) and [ 35 S] methyl tetrahydrofurfuryl sulfoxide (MTFSO) as substrates, the occurrence and involvement of both sulfide and sulfoxide oxygenases were demonstrated in rat liver microsomes. Both activities required reduced nicotinamide adenine dinucleotide phosphate (NADPH) and O 2 . The reaction products were isolated and identified as MTFSO and its sulfone, respectively. The apparent Michaelis constants were 6.7x10 -4 M for MTFS and 9.1x10 -15 M for NADPH with sulfide oxygenase and 5.6x10 -3 M for MTFSO and 5.0x10 -5 M for NADPH with sulfoxide oxygenase, respectively. P-chloromercuribenzoate, P-chloromercuribenzenesulfonate, HgCl 2 , and menadione strongly inhibited both oxygenases. Polyanions, such as inorganic phosphate, pyrophosphate, sulfate, and ATP stimulated both enzyme activities, especially that of sulfoxide oxygenase. One atom of 18 O 2 was incorporated into the products in both enzyme reactions. No appreciable incorporation was observed from H 2 18 O. These results indicate that both enzyme systems are typical monooxygenases. (auth.)

Bee venom protects SH-SY5Y human neuroblastoma cells from 1-methyl-4-phenylpyridinium-induced apoptotic cell death.

Science.gov (United States)

Doo, Ah-Reum; Kim, Seung-Nam; Kim, Seung-Tae; Park, Ji-Yeun; Chung, Sung-Hyun; Choe, Bo-Young; Chae, Younbyoung; Lee, Hyejung; Yin, Chang-Shik; Park, Hi-Joon

2012-01-06

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by progressive selective loss of dopaminergic neurons in the substantia nigra. Recently, bee venom was reported to protect dopaminergic neurons in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine induced mice PD model, however, the underlying mechanism is not fully understood. The objective of the present study is to investigate the neuroprotective mechanism of bee venom against Parkinsonian toxin, 1-methyl-4-phenylpyridine (MPP(+)), in SH-SY5Y human neuroblastoma cells. Our results revealed that bee venom pretreatment (1-100 ng/ml) increased the cell viability and decreased apoptosis assessed by DNA fragmentation and caspase-3 activity assays in MPP(+)-induced cytotoxicity in SH-SY5Y cells. Bee venom increased the anti-apoptotic Bcl-2 expression and decreased the pro-apoptotic Bax, cleaved PARP expressions. In addition, bee venom prevented the MPP(+)-induced suppression of Akt phosphorylation, and the neuroprotective effect of bee venom against MPP(+)-induced cytotoxicity was inhibited by a phosphatidylinositol 3-kinase (PI3K) inhibitor, LY294002. These results suggest that the anti-apoptotic effect of bee venom is mediated by the cell survival signaling, the PI3K/Akt pathway. These results provide new evidence for elucidating the mechanism of neuroprotection of bee venom against PD. Copyright © 2011 Elsevier B.V. All rights reserved.

SH2 and SH3 domains: elements that control interactions of cytoplasmic signaling proteins.

Science.gov (United States)

Koch, C A; Anderson, D; Moran, M F; Ellis, C; Pawson, T

1991-05-03

Src homology (SH) regions 2 and 3 are noncatalytic domains that are conserved among a series of cytoplasmic signaling proteins regulated by receptor protein-tyrosine kinases, including phospholipase C-gamma, Ras GTPase (guanosine triphosphatase)-activating protein, and Src-like tyrosine kinases. The SH2 domains of these signaling proteins bind tyrosine phosphorylated polypeptides, implicated in normal signaling and cellular transformation. Tyrosine phosphorylation acts as a switch to induce the binding of SH2 domains, thereby mediating the formation of heteromeric protein complexes at or near the plasma membrane. The formation of these complexes is likely to control the activation of signal transduction pathways by tyrosine kinases. The SH3 domain is a distinct motif that, together with SH2, may modulate interactions with the cytoskeleton and membrane. Some signaling and transforming proteins contain SH2 and SH3 domains unattached to any known catalytic element. These noncatalytic proteins may serve as adaptors to link tyrosine kinases to specific target proteins. These observations suggest that SH2 and SH3 domains participate in the control of intracellular responses to growth factor stimulation.

Preferred SH3 domain partners of ADAM metalloproteases include shared and ADAM-specific SH3 interactions.

Directory of Open Access Journals (Sweden)

Iivari Kleino

Full Text Available A disintegrin and metalloproteinases (ADAMs constitute a protein family essential for extracellular signaling and regulation of cell adhesion. Catalytic activity of ADAMs and their predicted potential for Src-homology 3 (SH3 domain binding show a strong correlation. Here we present a comprehensive characterization of SH3 binding capacity and preferences of the catalytically active ADAMs 8, 9, 10, 12, 15, 17, and 19. Our results revealed several novel interactions, and also confirmed many previously reported ones. Many of the identified SH3 interaction partners were shared by several ADAMs, whereas some were ADAM-specific. Most of the ADAM-interacting SH3 proteins were adapter proteins or kinases, typically associated with sorting and endocytosis. Novel SH3 interactions revealed in this study include TOCA1 and CIP4 as preferred partners of ADAM8, and RIMBP1 as a partner of ADAM19. Our results suggest that common as well as distinct mechanisms are involved in regulation and execution of ADAM signaling, and provide a useful framework for addressing the pathways that connect ADAMs to normal and aberrant cell behavior.

Synthesis of ethyl ( sup 14 CH sub 3 )methylmalonyl thioglycolate as a possible substrate analogue of ( sup 14 CH sub 3 )methylmalonyl coenzyme-A

Energy Technology Data Exchange (ETDEWEB)

Kovacs, I. (BIOGAL Pharmaceutical Works, Debrecen (Hungary)); Kovacs, Z. (Inst. of Nuclear Research, Debrecen (Hungary))

1991-11-01

Ethyl methylmalonyl thioglycolate is a potential substrate analogue of methylmalonyl-coenzyme-A (methylmalonyl-CoA) in the investigation of propionic acid metabolism. To prove this hypothesis, the tracer ethyl ({sup 14}CH{sub 3}) methylmalonyl thioglycolate was synthesized via methyl-Meldrum's acid to carry out the biochemical examinations. The method described can also be used to synthesize ({sup 14}CH{sub 3}) methylmalonyl-CoA by transesterification of active labelled methylmalonyl thiophenyl ester. This latter intermediate is chemically stable when stored at room temperature, and the unstable ({sup 14}CH{sub 3})methylmalonyl-CoA can be prepared in one step just preceeding the biochemical experiments. (author).

The Abl SH2-kinase linker naturally adopts a conformation competent for SH3 domain binding.

Science.gov (United States)

Chen, Shugui; Brier, Sébastien; Smithgall, Thomas E; Engen, John R

2007-04-01

The core of the Abelson tyrosine kinase (c-Abl) is structurally similar to Src-family kinases where SH3 and SH2 domains pack against the backside of the kinase domain in the down-regulated conformation. Both kinase families depend upon intramolecular association of SH3 with the linker joining the SH2 and kinase domains for suppression of kinase activity. Hydrogen deuterium exchange (HX) and mass spectrometry (MS) were used to probe intramolecular interaction of the c-Abl SH3 domain with the linker in recombinant constructs lacking the kinase domain. Under physiological conditions, the c-Abl SH3 domain undergoes partial unfolding, which is stabilized by ligand binding, providing a unique assay for SH3:linker interaction in solution. Using this approach, we observed dynamic association of the SH3 domain with the linker in the absence of the kinase domain. Truncation of the linker before W254 completely prevented cis-interaction with SH3, while constructs containing amino acids past this point showed SH3:linker interactions. The observation that the Abl linker sequence exhibits SH3-binding activity in the absence of the kinase domain is unique to Abl and was not observed with Src-family kinases. These results suggest that SH3:linker interactions may have a more prominent role in Abl regulation than in Src kinases, where the down-regulated conformation is further stabilized by a second intramolecular interaction between the C-terminal tail and the SH2 domain.

Cleavage of sp3 C-O bonds via oxidative addition of C-H bonds.

Science.gov (United States)

Choi, Jongwook; Choliy, Yuriy; Zhang, Xiawei; Emge, Thomas J; Krogh-Jespersen, Karsten; Goldman, Alan S

2009-11-04

(PCP)Ir (PCP = kappa(3)-C(6)H(3)-2,6-[CH(2)P(t-Bu)(2)](2)) is found to undergo oxidative addition of the methyl-oxygen bond of electron-poor methyl aryl ethers, including methoxy-3,5-bis(trifluoromethyl)benzene and methoxypentafluorobenzene, to give the corresponding aryloxide complexes (PCP)Ir(CH(3))(OAr). Although the net reaction is insertion of the Ir center into the C-O bond, density functional theory (DFT) calculations and a significant kinetic isotope effect [k(CH(3))(OAr)/k(CD(3))(OAr) = 4.3(3)] strongly argue against a simple insertion mechanism and in favor of a pathway involving C-H addition and alpha-migration of the OAr group to give a methylene complex followed by hydride-to-methylene migration to give the observed product. Ethoxy aryl ethers, including ethoxybenzene, also undergo C-O bond cleavage by (PCP)Ir, but the net reaction in this case is 1,2-elimination of ArO-H to give (PCP)Ir(H)(OAr) and ethylene. DFT calculations point to a low-barrier pathway for this reaction that proceeds through C-H addition of the ethoxy methyl group followed by beta-aryl oxide elimination and loss of ethylene. Thus, both of these distinct C-O cleavage reactions proceed via initial addition of a C(sp(3))-H bond, despite the fact that such bonds are typically considered inert and are much stronger than C-O bonds.

Theoretical study of the regioselectivity of the interaction of 3-methyl-4-pyrimidone and 1-methyl-2-pyrimidone with Lewis acids.

Science.gov (United States)

Kasende, Okuma Emile; Muya, Jules Tshishimbi; Broeckaert, Lies; Maes, Guido; Geerlings, Paul

2012-08-23

A density functional theory (DFT) study is performed to determine the stability of the complexes formed between either the N or O site of 3-methyl-4-pyrimidone and 1-methyl-2-pyrimidone molecules and different ligands. The studied ligands are boron and alkali Lewis acids, namely, B(CH(3))(3), HB(CH(3))(2), H(2)B(CH(3)), BH(3), H(2)BF, HBF(2), BF(3), Li(+), Na(+), and K(+). The acids are divided into two groups according to their hardness. The reactivity predictions, according to the molecular electrostatic potential (MEP) map and the natural bond orbital (NBO) analysis, are in agreement with the calculated relative stabilities. Our findings reveal a strong regioselectivity with borane and its derivatives preferring the nitrogen site in both pyrimidone isomers, while a preference for oxygen is observed for the alkali acids in the 3-methyl-4-pyrimidone molecule. The complexation of 1-methyl-2-pyrimidone with these hard alkali acids does not show any discrimination between the two sites due to the presence of a continuous delocalized density region between the nitrogen and the oxygen atoms. The preference of boron Lewis acids toward the N site is due to the stronger B-N bond as compared to the B-O bond. The influence of fluorine or methyl substitution on the boron atom is discussed through natural orbital analysis (NBO) concentrating on the overlap of the boron empty p-orbital with the F lone pairs and methyl hyperconjugation, respectively. The electrophilicity of the boron acids gives a good overall picture of the interaction capabilities with the Lewis base.

Theoretical spectroscopic characterization at low temperatures of S-methyl thioformate and O-methyl thioformate

International Nuclear Information System (INIS)

Senent, M. L.; Puzzarini, C.; Hochlaf, M.; Domínguez-Gómez, R.; Carvajal, M.

2014-01-01

Highly correlated ab initio methods are employed to determine spectroscopic properties at low temperatures of two S-analogs of methyl formate: S-methyl thioformate CH 3 -S-CHO (MSCHO) and O-methyl thioformate CH 3 -O-CHS (MOCHS). Both species are detectable and they are expected to play an important role in Astrochemistry. Molecular properties are compared with those of the O-analog, methyl formate. Both isomers present two conformers cis and trans. cis-CH 3 -S-CHO represents the most stable structure lying 4372.2 cm −1 below cis-CH 3 -O-CHS. The energy difference between the cis and trans forms is drastically lower for MSCHO (1134 cm −1 ) than for MOCHS (1963.6 cm −1 ). Harmonic and anharmonic fundamentals and the corresponding intensities, as well as the rotational constants for the ground vibrational and first excited torsional states and the centrifugal distortions constants, are provided. Low torsional energy levels have been obtained by solving variationally a two dimensional Hamiltonian expressed in terms of the two torsional degrees of freedom. The corresponding 2D potential energy surfaces have been computed at the CCSD(T)/aug-cc-pVTZ level of theory. The methyl torsional barriers V 3 (cis) are determined to be 139.7 cm −1 (CH 3 -S-CHO) and 670.4 cm −1 (CH 3 -O-CHS). The A/E splitting of ground torsional state has been estimated to be 0.438 cm −1 for CH 3 -S-CHO and negligible for CH 3 -O-CHS

N-[11C]methyl-3,4-methylenedioxyamphetamine (Ecstasy) and 2-methyl-N-[11C]methyl-4,5-methylenedioxyamphetamine. Synthesis and biodistribution studies

International Nuclear Information System (INIS)

Patt, M.; Machulla, H.J.; Guendisch, D.; Kovar, K.A.; Wuellner, U.; Blocher, A.

1999-01-01

In order to evaluate the neurobiological mechanism causing the psychogenic effects of methylenedioxy-derivatives of amphetamine, the carbon-11 labeled analogues of 3,4-methylenedioxymethamphetamine (MDMA), 2 and 2,N-dimethyl-4,5-methylenedioxyamphetamine (MADAM-6) 4 were prepared for application in in-vivo PET studies by methylation of 3,4-methylenedioxyamphetamine (MDA) 1 and 2-methyl-4,5-methylenedioxyamphetamine 3 with [ 11 C]CH 3 I. The radiochemical yield was determined in dependence on time, temperature and amount of precursor. The best conditions for a fast labeling reaction with carbon-11 on a preparative scale were found to be a reaction time of 10 min using 1 mg of the corresponding dimethyl-precursors 1 or 3, thus obtaining radiochemical yields of 60% (based on produced [ 11 C]CH 3 I). Biodistribution studies were performed in rats, a high brain to blood ratio of 7.5 was observed for [ 11 C]MDMA in contrast to a ratio of 3.7 for [ 11 C]MADAM-6. (author)

Differential Effects of Methyl-4-Phenylpyridinium Ion, Rotenone, and Paraquat on Differentiated SH-SY5Y Cells

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João Barbosa Martins

2013-01-01

Full Text Available Paraquat (PQ, a cationic nonselective bipyridyl herbicide, has been used as neurotoxicant to modulate Parkinson’s disease in laboratory settings. Other compounds like rotenone (ROT, a pesticide, and 1-methyl-4-phenylpyridinium ion (MPP+ have been widely used as neurotoxicants. We compared the toxicity of these three neurotoxicants using differentiated dopaminergic SH-SY5Y human cells, aiming to elucidate their differential effects. PQ-induced neurotoxicity was shown to be concentration and time dependent, being mitochondrial dysfunction followed by neuronal death. On the other hand, cells exposure to MPP+ induced mitochondrial dysfunction, but not cellular lyses. Meanwhile, ROT promoted both mitochondrial dysfunction and neuronal death, revealing a biphasic pattern. To further elucidate PQ neurotoxic mechanism, several protective agents were used. SH-SY5Y cells pretreatment with tiron (TIR and 2-hydroxybenzoic acid sodium salt (NaSAL, both antioxidants, and Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME, a nitric oxide synthase inhibitor, partially protected against PQ-induced cell injury. Additionally, 1-(2-[bis(4-fluorophenylmethoxy]ethyl-4-(3-phenyl-propylpiperazine (GBR 12909, a dopamine transporter inhibitor, and cycloheximide (CHX, a protein synthesis inhibitor, also partially protected against PQ-induced cell injury. In conclusion, we demonstrated that PQ, MPP+, and ROT exerted differential toxic effects on dopaminergic cells. PQ neurotoxicity occurred through exacerbated oxidative stress, with involvement of uptake through the dopamine transporter and protein synthesis.

Atractylenolide-I Protects Human SH-SY5Y Cells from 1-Methyl-4-Phenylpyridinium-Induced Apoptotic Cell Death

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Sandeep Vasant More

2017-05-01

Full Text Available Oxidative stress and apoptosis are the major mechanisms that induce dopaminergic cell death. Our study investigates the protective effects of atractylenolide-I (ATR-I on 1-methyl-4-phenylpyridinium (MPP+-induced cytotoxicity in human dopaminergic SH-SY5Y cells, as well as its underlying mechanism. Our experimental data indicates that ATR-I significantly inhibits the loss of cell viability induced by MPP+ in SH-SY5Y cells. To further unravel the mechanism, we examined the effect of ATR-I on MPP+-induced apoptotic cell death characterized by an increase in the Bax/Bcl-2 mRNA ratio, the release of cytochrome-c, and the activation of caspase-3 leading to elevated levels of cleaved poly(ADP-ribose polymerase (PARP resulting in SH-SY5Y cell death. Our results demonstrated that ATR-I decreases the level of pro-apoptotic proteins induced by MPP+ and also restored Bax/Bcl-2 mRNA levels, which are critical for inducing apoptosis. In addition, ATR-I demonstrated a significant increase in the protein expression of heme-oxygenase in MPP+-treated SH-SY5Y cells. These results suggest that the pharmacological effect of ATR-I may be, at least in part, caused by the reduction in pro-apoptotic signals and also by induction of anti-oxidant protein.

Theoretical spectroscopic characterization at low temperatures of S-methyl thioformate and O-methyl thioformate

Energy Technology Data Exchange (ETDEWEB)

Senent, M. L., E-mail: senent@iem.cfmac.csic.es [Departamento de Química y Física Teóricas, Instituto de Estructura de la Materia, IEM-C.S.I.C., Serrano 121, Madrid 28006 (Spain); Puzzarini, C., E-mail: cristina.puzzarini@unibo.it [Dipartimento di Chimica G. Ciamician, Università di Bologna, Via F. Selmi 2, I-40126 Bologna (Italy); Hochlaf, M., E-mail: hochlaf@univ-mlv.fr [Laboratoire de Modélisation et Simulation Multi Echelle, Université Paris-Est, MSME UMR 8208 CNRS, 5 boulevard Descartes, 77454 Marne-la-Vallée (France); Domínguez-Gómez, R., E-mail: rosa.dominguez@upm.es [Departamento de Ingeniería Civil, Cátedra de Química, E.U.I.T. Obras Públicas, Universidad Politécnica de Madrid, Madrid (Spain); Carvajal, M., E-mail: miguel.carvajal@dfa.uhu.es [Departamento de Física Aplicada, Facultad de Ciencias Experimentales, Unidad Asociada IEM-CSIC-U.Huelva, Universidad de Huelva, 21071 Huelva (Spain)

2014-09-14

Highly correlated ab initio methods are employed to determine spectroscopic properties at low temperatures of two S-analogs of methyl formate: S-methyl thioformate CH{sub 3}-S-CHO (MSCHO) and O-methyl thioformate CH{sub 3}-O-CHS (MOCHS). Both species are detectable and they are expected to play an important role in Astrochemistry. Molecular properties are compared with those of the O-analog, methyl formate. Both isomers present two conformers cis and trans. cis-CH{sub 3}-S-CHO represents the most stable structure lying 4372.2 cm{sup −1} below cis-CH{sub 3}-O-CHS. The energy difference between the cis and trans forms is drastically lower for MSCHO (1134 cm{sup −1}) than for MOCHS (1963.6 cm{sup −1}). Harmonic and anharmonic fundamentals and the corresponding intensities, as well as the rotational constants for the ground vibrational and first excited torsional states and the centrifugal distortions constants, are provided. Low torsional energy levels have been obtained by solving variationally a two dimensional Hamiltonian expressed in terms of the two torsional degrees of freedom. The corresponding 2D potential energy surfaces have been computed at the CCSD(T)/aug-cc-pVTZ level of theory. The methyl torsional barriers V{sub 3}(cis) are determined to be 139.7 cm{sup −1} (CH{sub 3}-S-CHO) and 670.4 cm{sup −1} (CH{sub 3}-O-CHS). The A/E splitting of ground torsional state has been estimated to be 0.438 cm{sup −1} for CH{sub 3}-S-CHO and negligible for CH{sub 3}-O-CHS.

Crystal structures of titanium–aluminium and –gallium complexes bearing two μ2-CH3 units

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Tim Oswald

2017-05-01

Full Text Available The isotypic crystal structures of two titanocene complexes containing an EMe3 unit (E = Al, Ga; Me = methyl with two μ2-coordinating methyl groups, namely [μ-1(η5-(adamantan-1-yl-2κC1cycylopentadienyl]di-μ2-methyl-methyl-2κC-[1(η5-pentamethylcyclopentadienyl]aluminiumtitanium(III, [AlTi(CH33(C10H15(C15H18], and [μ-1(η5-(adamantan-1-yl-2κC1cycylopentadienyl]di-μ2-methyl-methyl-2κC-[1(η5-pentamethylcyclopentadienyl]galliumtitanium(III, [GaTi(CH33(C10H15(C15H18], are reported. Reacting a dinuclear nitrogen-bridged low-valent titanium(III complex with the Lewis acids AlMe3 or GaMe3 results in the loss of molecular dinitrogen and the formation of two monomeric titanocene(III fragments bearing two μ2-bridging methyl groups. Single crystal X-ray diffraction reveals the formation of a new E—C bond involving the pentafulvene ligand while the bridging and terminal methyl groups remain intact.

Effects of collision energy and vibrational excitation of CH3 + cations on its reactivity with hydrocarbons: But-2-yne CH3CCCH3 as reagent partner

Science.gov (United States)

Cernuto, Andrea; Lopes, Allan; Romanzin, Claire; Cunha de Miranda, Barbara; Ascenzi, Daniela; Tosi, Paolo; Tonachini, Glauco; Maranzana, Andrea; Polášek, Miroslav; Žabka, Jan; Alcaraz, Christian

2017-10-01

The methyl carbocation is ubiquitous in gaseous environments, such as planetary ionospheres, cometary comae, and the interstellar medium, as well as combustion systems and plasma setups for technological applications. Here we report on a joint experimental and theoretical study on the mechanism of the reaction CH3 + + CH3CCCH3 (but-2-yne, also known as dimethylacetylene), by combining guided ion beam mass spectrometry experiments with ab initio calculations of the potential energy hypersurface. Such a reaction is relevant in understanding the chemical evolution of Saturn's largest satellite, Titan. Two complementary setups have been used: in one case, methyl cations are generated via electron ionization, while in the other case, direct vacuum ultraviolet photoionization with synchrotron radiation of methyl radicals is used to study internal energy effects on the reactivity. Absolute reactive cross sections have been measured as a function of collision energy, and product branching ratios have been derived. The two most abundant products result from electron and hydride transfer, occurring via direct and barrierless mechanisms, while other channels are initiated by the electrophilic addition of the methyl cation to the triple bond of but-2-yne. Among the minor channels, special relevance is placed on the formation of C5H7 +, stemming from H2 loss from the addition complex. This is the only observed condensation product with the formation of new C—C bonds, and it might represent a viable pathway for the synthesis of complex organic species in astronomical environments and laboratory plasmas.

SH3 domain tyrosine phosphorylation--sites, role and evolution.

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Zuzana Tatárová

Full Text Available BACKGROUND: SH3 domains are eukaryotic protein domains that participate in a plethora of cellular processes including signal transduction, proliferation, and cellular movement. Several studies indicate that tyrosine phosphorylation could play a significant role in the regulation of SH3 domains. RESULTS: To explore the incidence of the tyrosine phosphorylation within SH3 domains we queried the PhosphoSite Plus database of phosphorylation sites. Over 100 tyrosine phosphorylations occurring on 20 different SH3 domain positions were identified. The tyrosine corresponding to c-Src Tyr-90 was by far the most frequently identified SH3 domain phosphorylation site. A comparison of sequences around this tyrosine led to delineation of a preferred sequence motif ALYD(Y/F. This motif is present in about 15% of human SH3 domains and is structurally well conserved. We further observed that tyrosine phosphorylation is more abundant than serine or threonine phosphorylation within SH3 domains and other adaptor domains, such as SH2 or WW domains. Tyrosine phosphorylation could represent an important regulatory mechanism of adaptor domains. CONCLUSIONS: While tyrosine phosphorylation typically promotes signaling protein interactions via SH2 or PTB domains, its role in SH3 domains is the opposite - it blocks or prevents interactions. The regulatory function of tyrosine phosphorylation is most likely achieved by the phosphate moiety and its charge interfering with binding of polyproline helices of SH3 domain interacting partners.

Efficacy and role of inulin in mitigation of enteric sulfur-containing odor in pigs.

Science.gov (United States)

Deng, Yuan-Fan; Liu, Yuan-Yuan; Zhang, Yi-Tao; Wang, Yan; Liang, Juan-Boo; Tufarelli, Vincenzo; Laudadio, Vito; Liao, Xin-Di

2017-06-01

The efficacy and role of inulin in the mitigation of enteric sulfur-containing odor gases hydrogen sulfide (H 2 S) and methyl mercaptan (CH 3 SH) in pigs were examined in this study. Twelve Duroc × Landrace × Yorkshire male finisher pigs (60.7 ± 1.9 kg), housed individually in open-circuit respiration chambers, were randomly assigned to two dietary groups, namely basal diet (control) and basal diet supplemented with 1% (w/w) inulin. At the end of the 45 day experiment, pigs were slaughtered and volatile fatty acid (VFA) concentration, sulfate radical (SO 4 2 - ) concentration, population of sulfate-reducing bacteria (SRB) and expression of methionine gamma-lyase (MGL) gene were determined in contents from the caecum, colon (two segments) and rectum. Metabonomic analysis was used to compare differences in biochemical composition, and the Illumina MiSeq procedure to investigate differences in bacterial components, in the different parts of the large intestine between inulin-supplemented and inulin-free (control) groups. Inulin decreased (P inulin treatment, whereas valerate concentration and MGL mRNA expression decreased (P inulin-supplemented pigs, suggesting that inulin mitigates H 2 S generation from the SO 4 2 - reduction pathway by reducing the growth of SRB. The results showed that inulin mitigates CH 3 SH generation via three methionine degradation metabolic pathways and H 2 S generation from two cysteine degradation metabolic pathways, thus resulting in increased synthesis of these two sulfur-containing amino acids in the pig large intestine. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Synthesis of Fe3O4@SiO2@OSi(CH2)3NHRN(CH2PPh2)2PdCl2 type nanocomposite complexes: Highly efficient and magnetically-recoverable catalysts in vitamin K3 synthesis.

Science.gov (United States)

Uruş, Serhan

2016-12-15

The synthesis of aminomethylphosphine-metal complexes have opened a new perspective to the catalytic applications of organic compounds. Magnetic Fe3O4 nano-core was synthesized using the closed quartz tube with Teflon cover and microwaved 200°C for 1h with power controlled instrument set to max. 600W. Novel nano-composite supported; Fe3O4@SiO2(CH2)3NHArN(CH2PPh2)2 and Fe3O4@SiO2(CH2)3N(CH2PPh2)2 type bis(diphenylphosphinomethyl)amino ligands and their Pd(II) complexes have been synthesized and characterized with FT-IR, SEM, EDX, TEM, UV-Visible, XRD and TG/DTA techniques. All the complexes were used as heterogeneous catalysts in the oxidation of 2-methyl naphthalene (2MN) to 2-methyl-1, 4-naphthoquinone (vitamin K3, menadione, 2MNQ) in the presence of hydrogen peroxide and acetic acid. Selectivity reached about 55-60% with a conversion of 90-96% using the nano-magnetite supported aminomethylphosphine-Pd(II) complexes. The complexes were very active in three times in the catalytic recycling experiments in five catalytic cycles. Copyright © 2016 Elsevier Ltd. All rights reserved.

Rate Constant and RRKM Product Study for the Reaction Between CH3 and C2H3 at T = 298K

Science.gov (United States)

Thorn, R. Peyton, Jr.; Payne, Walter A., Jr.; Chillier, Xavier D. F.; Stief, Louis J.; Nesbitt, Fred L.; Tardy, D. C.

2000-01-01

The total rate constant k1 has been determined at P = 1 Torr nominal pressure (He) and at T = 298 K for the vinyl-methyl cross-radical reaction CH3 + C2H3 yields products. The measurements were performed in a discharge flow system coupled with collision-free sampling to a mass spectrometer operated at low electron energies. Vinyl and methyl radicals were generated by the reactions of F with C2H4 and CH4, respectively. The kinetic studies were performed by monitoring the decay of C2H3 with methyl in excess, 6 rate coefficient was determined to be k1(298 K) = (1.02 +/- 0.53)x10(exp -10) cubic cm/molecule/s with the quoted uncertainty representing total errors. Numerical modeling was required to correct for secondary vinyl consumption by reactions such as C2H3 + H and C2H3 + C2H3. The present result for k1 at T = 298 K is compared to two previous studies at high pressure (100-300 Torr He) and to a very recent study at low pressure (0.9-3.7 Torr He). Comparison is also made with the rate constant for the similar reaction CH3 + C2H5 and with a value for k1 estimated by the geometric mean rule employing values for k(CH3 + CH3) and k(C2H3 + C2H3). Qualitative product studies at T = 298 K and 200 K indicated formation of C3H6, C2H2, and C2H5 as products of the combination-stabilization, disproportionation, and combination-decomposition channels, respectively, of the CH3 + C2H3 reaction. We also observed the secondary C4H8 product of the subsequent reaction of C3H5 with excess CH3; this observation provides convincing evidence for the combination-decomposition channel yielding C3H5 + H. RRKM calculations with helium as the deactivator support the present and very recent experimental observations that allylic C-H bond rupture is an important path in the combination reaction. The pressure and temperature dependencies of the branching fractions are also predicted.

Kinetics of the reactions H+C2H4->C2H5, H+C2H5->2CH3 and CH3+C2H5->products studies by pulse radiolysis combined with infrared diode laser spectroscopy

DEFF Research Database (Denmark)

Sillesen, A.; Ratajczak, E.; Pagsberg, P.

1993-01-01

Formation of methyl radicals via the consecutive reactions H+C2H4+M-->C2H5+M (1) and H+C2H5-->CH3+CH3 (2a) was initiated by pulse radiolysis of 10-100 mbar H-2 in the presence of ethylene. The kinetics of CH3 Were studied by monitoring the transient infrared absorption at the Q(3, 3) line of the ...

Genome Sequence of Saccharomyces cerevisiae Strain Kagoshima No. 2, Used for Brewing the Japanese Distilled Spirit Shōchū.

Science.gov (United States)

Mori, Kazuki; Kadooka, Chihiro; Masuda, Chika; Muto, Ai; Okutsu, Kayu; Yoshizaki, Yumiko; Takamine, Kazunori; Futagami, Taiki; Tamaki, Hisanori

2017-10-12

Here, we report a draft genome sequence of Saccharomyces cerevisiae strain Kagoshima no. 2, which is used for brewing shōchū, a traditional distilled spirit in Japan. The genome data will facilitate an understanding of the evolutional traits and genetic background related to the characteristic features of strain Kagoshima no. 2. Copyright © 2017 Mori et al.

Transparent and flexible photodetectors based on CH3NH3PbI3 perovskite nanoparticles

Science.gov (United States)

Jeon, Young Pyo; Woo, Sung Jun; Kim, Tae Whan

2018-03-01

Transparent and flexible photodetectors (PDs) based on CH3NH3PbI3 perovskite nanoparticles (NPs) were fabricated by using co-evaporation of methyl ammonium iodide and lead iodide. X-ray diffraction patterns and high-resolution transmission electron microscopy images demonstrated the formation of perovskite NPs. The optical transmittance of the perovskite NPs/glass was above 80% over the entire range of visible wavelengths, indicative of high transparency. The PDs based on CH3NH3PbI3 perovskite NPs were sensitive to a broad range of visible light from 450 to 650 nm. The currents in the PDs under exposure to red, green, and blue light-emitting diodes were enhanced to 5, 10, and 20 times that of the PD in the dark, respectively. The rise and the decay times of the PDs were 50 and 120 μs. The current in the perovskite NP PD on a polyethylene terephthalate substrate was enhanced by approximately 69% when the NP PD was exposed to a blue LED emitting at a wavelength of 459 nm. Despite multiple bending, the transparent and flexible PDs based on methyl ammonium iodide and lead iodide NPs showed reproducibility and high stability in performance.

Biochemical and genetic analysis of the Drk SH2/SH3 adaptor protein of Drosophila.

Science.gov (United States)

Raabe, T; Olivier, J P; Dickson, B; Liu, X; Gish, G D; Pawson, T; Hafen, E

1995-06-01

The Drk SH3-SH2-SH3 adaptor protein has been genetically identified in a screen for rate-limiting components acting downstream of the Sevenless (Sev) receptor tyrosine kinase in the developing eye of Drosophila. It provides a link between the activated Sev receptor and Sos, a guanine nucleotide release factor that activates Ras1. We have used a combined biochemical and genetic approach to study the interactions between Sev, Drk and Sos. We show that Tyr2546 in the cytoplasmic tail of Sev is required for Drk binding, probably because it provides a recognition site for the Drk SH2 domain. Interestingly, a mutation at this site does not completely block Sev function in vivo. This may suggest that Sev can signal in a Drk-independent, parallel pathway or that Drk can also bind to an intermediate docking protein. Analysis of the Drk-Sos interaction has identified a high affinity binding site for Drk SH3 domains in the Sos tail. We show that the N-terminal Drk SH3 domain is primarily responsible for binding to the tail of Sos in vitro, and for signalling to Ras in vivo.

Crystal structure of Src-like adaptor protein 2 reveals close association of SH3 and SH2 domains through β-sheet formation.

Science.gov (United States)

Wybenga-Groot, Leanne E; McGlade, C Jane

2013-12-01

The Src-like adaptor proteins (SLAP/SLAP2) are key components of Cbl-dependent downregulation of antigen receptor, cytokine receptor, and receptor tyrosine kinase signaling in hematopoietic cells. SLAP and SLAP2 consist of adjacent SH3 and SH2 domains that are most similar in sequence to Src family kinases (SFKs). Notably, the SH3-SH2 connector sequence is significantly shorter in SLAP/SLAP2 than in SFKs. To understand the structural implication of a short SH3-SH2 connector sequence, we solved the crystal structure of a protein encompassing the SH3 domain, SH3-SH2 connector, and SH2 domain of SLAP2 (SLAP2-32). While both domains adopt typical folds, the short SH3-SH2 connector places them in close association. Strand βe of the SH3 domain interacts with strand βA of the SH2 domain, resulting in the formation of a continuous β sheet that spans the length of the protein. Disruption of the SH3/SH2 interface through mutagenesis decreases SLAP-32 stability in vitro, consistent with inter-domain binding being an important component of SLAP2 structure and function. The canonical peptide binding pockets of the SH3 and SH2 domains are fully accessible, in contrast to other protein structures that display direct interaction between SH3 and SH2 domains, in which either peptide binding surface is obstructed by the interaction. Our results reveal potential sites of novel interaction for SH3 and SH2 domains, and illustrate the adaptability of SH2 and SH3 domains in mediating interactions. As well, our results suggest that the SH3 and SH2 domains of SLAP2 function interdependently, with implications on their mode of substrate binding. © 2013.

Effect of the SH3-SH2 domain linker sequence on the structure of Hck kinase.

Science.gov (United States)

Meiselbach, Heike; Sticht, Heinrich

2011-08-01

The coordination of activity in biological systems requires the existence of different signal transduction pathways that interact with one another and must be precisely regulated. The Src-family tyrosine kinases, which are found in many signaling pathways, differ in their physiological function despite their high overall structural similarity. In this context, the differences in the SH3-SH2 domain linkers might play a role for differential regulation, but the structural consequences of linker sequence remain poorly understood. We have therefore performed comparative molecular dynamics simulations of wildtype Hck and of a mutant Hck in which the SH3-SH2 domain linker is replaced by the corresponding sequence from the homologous kinase Lck. These simulations reveal that linker replacement not only affects the orientation of the SH3 domain itself, but also leads to an alternative conformation of the activation segment in the Hck kinase domain. The sequence of the SH3-SH2 domain linker thus exerts a remote effect on the active site geometry and might therefore play a role in modulating the structure of the inactive kinase or in fine-tuning the activation process itself.

Abl N-terminal cap stabilization of SH3 domain dynamics.

Science.gov (United States)

Chen, Shugui; Dumitrescu, Teodora Pene; Smithgall, Thomas E; Engen, John R

2008-05-27

Crystal structures and other biochemical data indicate that the N-terminal cap (NCap) region of the Abelson tyrosine kinase (c-Abl) is important for maintaining the downregulated conformation of the kinase domain. The exact contributions that the NCap makes in stabilizing the various intramolecular interactions within c-Abl are less clear. While the NCap appears to be important for locking the SH3 and SH2 domains to the back of the kinase domain, there may be other more subtle elements of regulation. Hydrogen exchange (HX) and mass spectrometry (MS) were used to determine if the NCap contributes to intramolecular interactions involving the Abl SH3 domain. Under physiological conditions, the Abl SH3 domain underwent partial unfolding and its unfolding half-life was slowed during binding to the SH2 kinase linker, providing a unique assay for testing NCap-induced stabilization of the SH3 domain in various constructs. The results showed that the NCap stabilizes the dynamics of the SH3 domain in certain constructs but does not increase the relative affinity of the SH3 domain for the native SH2 kinase linker. The stabilization effect was absent in constructs of just the NCap and SH3 but was obvious when the SH2 domain and the SH2 kinase linker were present. These results suggest that interactions between the NCap and the SH3 domain can contribute to c-Abl stabilization in constructs that contain at least the SH2 domain, an effect that may partially compensate for the absence of the negative regulatory C-terminal tail found in the related Src family of kinases.

Kinetics of the Reaction of CH3O2 Radicals with OH Studied over the 292-526 K Temperature Range.

Science.gov (United States)

Yan, Chao; Kocevska, Stefani; Krasnoperov, Lev N

2016-08-11

Reaction of methyl peroxy radicals with hydroxyl radicals, CH3O2 + OH → CH3O + HO2 (1a) and CH3O2 + OH → CH2OO + H2O (1b) was studied using pulsed laser photolysis coupled to transient UV-vis absorption spectroscopy over the 292-526 K temperature range and pressure 1 bar (bath gas He). Hydroxyl radicals were generated in the reaction of electronically excited oxygen atoms O((1)D), produced in the photolysis of N2O at 193.3 nm, with H2O. Methyl peroxy radicals were generated in the reaction of methyl radicals, CH3, produced in the photolysis of acetone at 193.3 nm, and subsequent reaction of CH3 with O2. Temporal profiles of OH were monitored via transient absorption of light from a DC discharge H2O/Ar low-pressure resonance lamp at ca. 308 nm. The absolute intensity of the photolysis light was determined by accurate in situ actinometry based on the ozone formation in the presence of molecular oxygen. The overall rate constant of the reaction is k1a+1b = (8.4 ± 1.7) × 10(-11)(T/298 K)(-0.81) cm(3) molecule(-1) s(-1) (292-526 K). The branching ratio of channel 1b at 298 K is less than 5%.

The reaction of fluorine atoms with methanol: yield of CH3O/CH2OH and rate constant of the reactions CH3O + CH3O and CH3O + HO2.

Science.gov (United States)

Assaf, Emmanuel; Schoemaecker, Coralie; Vereecken, Luc; Fittschen, Christa

2018-04-25

Xenondifluoride, XeF2, has been photolysed in the presence of methanol, CH3OH. Two reaction pathways are possible: F + CH3OH → CH2OH + HF and F + CH3OH → CH3O + HF. Both products, CH2OH and CH3O, will be converted to HO2 in the presence of O2. The rate constants for the reaction of both radicals with O2 differ by more than 3 orders of magnitude, which allows an unequivocal distinction between the two reactions when measuring HO2 concentrations in the presence of different O2 concentrations. The following yields have then been determined from time-resolved HO2 profiles: φCH2OH = (0.497 ± 0.013) and φCH3O = (0.503 ± 0.013). Experiments under low O2 concentrations lead to reaction mixtures containing nearly equal amounts of HO2 (converted from the first reaction) and CH3O (from the second reaction). The subsequent HO2 decays are very sensitive to the rate constants of the reaction between these two radicals and the following rate constants have been obtained: k(CH3O + CH3O) = (7.0 ± 1.4) × 10-11 cm3 s-1 and k(CH3O + HO2) = (1.1 ± 0.2) × 10-10 cm3 s-1. The latter reaction has also been theoretically investigated on the CCSD(T)//M06-2X/aug-cc-pVTZ level of theory and CH3OH + O2 have been identified as the main products. Using μVTST, a virtually pressure independent rate constant of k(CH3O + HO2) = 4.7 × 10-11 cm3 s-1 has been obtained, in good agreement with the experiment.

Photodissociation of gaseous CH3COSH at 248 nm by time-resolved Fourier-transform infrared emission spectroscopy: Observation of three dissociation channels

International Nuclear Information System (INIS)

Hu, En-Lan; Tsai, Po-Yu; Fan, He; Lin, King-Chuen

2013-01-01

Upon one-photon excitation at 248 nm, gaseous CH 3 C(O)SH is dissociated following three pathways with the products of (1) OCS + CH 4 , (2) CH 3 SH + CO, and (3) CH 2 CO + H 2 S that are detected using time-resolved Fourier-transform infrared emission spectroscopy. The excited state 1 (n O , π * CO ) has a radiative lifetime of 249 ± 11 ns long enough to allow for Ar collisions that induce internal conversion and enhance the fragment yields. The rate constant of collision-induced internal conversion is estimated to be 1.1 × 10 −10 cm 3 molecule −1 s −1 . Among the primary dissociation products, a fraction of the CH 2 CO moiety may undergo further decomposition to CH 2 + CO, of which CH 2 is confirmed by reaction with O 2 producing CO 2 , CO, OH, and H 2 CO. Such a secondary decomposition was not observed previously in the Ar matrix-isolated experiments. The high-resolution spectra of CO are analyzed to determine the ro-vibrational energy deposition of 8.7 ± 0.7 kcal/mol, while the remaining primary products with smaller rotational constants are recognized but cannot be spectrally resolved. The CO fragment detected is mainly ascribed to the primary production. A prior distribution method is applied to predict the vibrational distribution of CO that is consistent with the experimental findings.

Chronic ethanol exposure induces SK-N-SH cell apoptosis by increasing N-methyl-D-aspartic acid receptor expression and intracellular calcium.

Science.gov (United States)

Wang, Hongbo; Wang, Xiaolong; Li, Yan; Yu, Hao; Wang, Changliang; Feng, Chunmei; Xu, Guohui; Chen, Jiajun; You, Jiabin; Wang, Pengfei; Wu, Xu; Zhao, Rui; Zhang, Guohua

2018-04-01

It has been identified that chronic ethanol exposure damages the nervous system, particularly neurons. There is scientific evidence suggesting that neuronal loss caused by chronic ethanol exposure has an association with neuron apoptosis and intracellular calcium oscillation is one of the primary inducers of apoptosis. Therefore, the present study aimed to investigate the inductive effects of intracellular calcium oscillation on apoptosis in SK-N-SH human neuroblastoma cells and the protective effects of the N-methyl-D-aspartic acid receptor (NMDAR) antagonist, memantine, on SK-N-SH cell apoptosis caused by chronic ethanol exposure. SK-N-SH cells were treated with 100 mM ethanol and memantine (4 µM) for 2 days. Protein expression of NR1 was downregulated by RNA interference (RNAi). Apoptosis was detected by Annexin V/propidium iodide (PI) double-staining and flow cytometry and cell viability was detected using an MTS kit. Fluorescence dual wavelength spectrophotometry was used to determine the intracellular calcium concentration and the levels of NR1 and caspase-3 were detected using western blotting. NR1 mRNA levels were also detected using qPCR. It was found that chronic ethanol exposure reduced neuronal cell viability and caused apoptosis of SK-N-SH cells, and the extent of damage in SK-N-SH cells was associated with ethanol exposure concentration and time. In addition, chronic ethanol exposure increased the concentration of intracellular calcium in SK-N-SH cells by inducing the expression of NMDAR, resulting in apoptosis, and memantine treatment reduced ethanol-induced cell apoptosis. The results of the present study indicate that the application of memantine may provide a novel strategy for the treatment of alcoholic dementia.

EPR study of gamma-irradiated N-methyl-L-alanine, DL-2-methyl glutamic acid hemihydrate and Di-leucine hydrochloride in solid state

Science.gov (United States)

Sütçü, Kerem; Osmanoğlu, Y. Emre

2017-12-01

In this study, it was aimed to investigate ɣ-irradiated powders of N-methyl-L-alanine (NMLA), DL-2-methyl glutamic acid hemihydrate (DL2MGAH), and Di-leucine hydrochloride (DLHCl) at room temperature by electron paramagnetic resonance spectroscopy. After the γ-irradiation the samples indicated the existence of the CH3ĊNHCH3COOH, HOOCCH3NH2CĊHCH2COOH·1/2H2O and (CH3)2ĊCH2CH NHCOOHCOCH (NH2HCl) CH2CH (CH3)2 radicals, respectively. The spectral parameters of the radicals were determined. The results were compared with the earlier studies and discussed accordingly.

Rate constants for the reactions of OH with CH3Cl, CH2Cl2, CHCl3, and CH3Br

Science.gov (United States)

Hsu, K.-J.; Demore, W. B.

1994-01-01

Rate constants for the reactions of OH with CH3Cl, CH2Cl2, CHCl3, and CH3Br have been measured by a relative rate technique in which the reaction rate of each compound was compared to that of HFC-152a (CH3CHF2) and (for CH2Cl2) HFC-161 (CH3CH2F). Using absolute rate constants for HFC-152a and HFC-161, which we have determined relative to those for CH4, CH3CCl3, and C2H6, temperature dependent rate constants of both compounds were derived. The derived rate constant for CH3Br is in good agreement with recent absolute measurements. However, for the chloromethanes all the rate constants are lower at atmospheric temperatures than previously reported, especially for CH2Cl2 where the present rate constant is about a factor of 1.6 below the JPL 92-20 value. The new rate constant appears to resolve a discrepancy between the observed atmospheric concentrations and those calculated from the previous rate constant and estimated release rates.

Increased recombination of CH3 radicals on stainless steel

International Nuclear Information System (INIS)

Gorodetsky, A.E.; Zalavutdinov, R.Kh.; Zakharov, A.P.; Vnukov, S.P.; Varshavskaya, I.G.; Makhankov, A.N.; Mazul, I.V.; Federici, G.

2005-01-01

By using a so-called 'stream technique', which consists of flowing gas in laminar regime along a quartz tube, we determine that CH 3 radicals are completely removed from the pumped mixture (CH 4 /C X H Y /H 2 /H/CH 3 ) after several hundred collisions with the inner surface of a stainless steel insert (T = 380-470 K). The methyl sticking coefficient decreased to ∼10 -6 and the recombination coefficient increased up to ∼0.01 at impingement with the metal surface. After passing through the heated zone no hydrocarbon deposition occurred at 300 K. However, unsaturated hydrocarbons, which formed in discharge zone and appeared as a result of interaction of radicals with stainless steel, condensed in a liquid phase at a temperature of ∼130 K and partial pressure of 0.01-0.1 Pa. Liquid films underwent partial polymerization and formed island deposits, which were stable at 300 K

Nuclear Hyperfine Structure in the Donor – Acceptor Complexes (CH3)3N-BF3 and (CH)33N-B(CH3)3

Science.gov (United States)

The donor-acceptor complexes (CH3)3N-BF3 and (CH3)3N-B(CH3)3 have been reinvestigated at high resolution by rotational spectroscopy in a supersonic jet. Nuclear hyperfine structure resulting from both nitrogen and boron has been resolved and quadrupole coupling constants have bee...

Molecular dissection of the interaction between the SH3 domain and the SH2-Kinase Linker region in PTK6.

Science.gov (United States)

Kim, Han Ie; Jung, Jinwon; Lee, Eun-Saem; Kim, Yong-Chul; Lee, Weontae; Lee, Seung-Taek

2007-11-03

PTK6 (also known as Brk) is an intracellular tyrosine kinase that contains SH3, SH2, and tyrosine kinase catalytic (Kinase) domains. The SH3 domain of PTK6 interacts with the N-terminal half of the linker (Linker) region between the SH2 and Kinase domains. Site-directed mutagenesis and surface plasmon resonance studies showed that a tryptophan residue (Trp44) in the SH3 domain and proline residues in the Linker region, in the order of Pro177, Pro175, and Pro179, contribute to the interaction. The three-dimensional modeled structure of the SH3-Linker complex was in agreement with the biochemical data. Disruption of the intramolecular interaction between the SH3 domain and the Linker region by mutation of Trp44, Pro175, Pro177, and Pro179 markedly increased the catalytic activity of PTK6 in HEK 293 cells. These results demonstrate that Trp44 in the SH3 domain and Pro177, Pro175, and Pro179 in the N-terminal half of the Linker region play important roles in the SH3-Linker interaction to maintain the protein in an inactive conformation along with the phosphorylated Tyr447-SH2 interaction.

Biochemical and genetic analysis of the Drk SH2/SH3 adaptor protein of Drosophila.

OpenAIRE

Raabe, T; Olivier, J P; Dickson, B J; Liu, X; Gish, G D; Pawson, T; Hafen, E

1995-01-01

The Drk SH3-SH2-SH3 adaptor protein has been genetically identified in a screen for rate-limiting components acting downstream of the Sevenless (Sev) receptor tyrosine kinase in the developing eye of Drosophila. It provides a link between the activated Sev receptor and Sos, a guanine nucleotide release factor that activates Ras1. We have used a combined biochemical and genetic approach to study the interactions between Sev, Drk and Sos. We show that Tyr2546 in the cytoplasmic tail of Sev is r...

In vitro effects of Melaleuca alternifolia essential oil on growth and production of volatile sulphur compounds by oral bacteria

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Talita Signoreti GRAZIANO

Full Text Available ABSTRACT Objective Halitosis can be caused by microorganisms that produce volatile sulphur compounds (VSCs, which colonize the surface of the tongue and subgingival sites. Studies have reported that the use of natural products can reduce the bacterial load and, consequently, the development of halitosis. The aim of this study was to evaluate the antimicrobial activity of the essential oil of Melaleuca alternifolia on the growth and volatile sulphur compound (VSC production of oral bacteria compared with chlorhexidine. Material and Methods The effects of these substances were evaluated by the Minimum Inhibitory Concentration (MIC and Minimum Bactericidal Concentration (MBC in planktonic cultures of Porphyromonas gingivalis and Porphyromonas endodontalis. In addition, gas chromatography analyses were performed to measure the concentration of VSCs from bacterial cultures and to characterize M. alternifolia oil components. Results The MIC and MBC values were as follows: M. alternifolia - P. gingivalis (MIC and MBC=0.007%, P. endodontalis (MIC and MBC=0.007%=0.5%; chlorhexidine - P. gingivalis and P. endodontalis (MIC and MBC=1.5 mg/mL. M. alternifolia significantly reduced the growth and production of hydrogen sulfide (H2S by P. gingivalis (p<0.05, ANOVA-Dunnet and the H2S and methyl mercaptan (CH3SH levels of P. endodontalis (p<0.05, ANOVA-Dunnet. Chlorhexidine reduced the growth of both microorganisms without altering the production of VSC in P. endodontalis. For P. gingivalis, the production of H2S and CH3SH decreased (p<0.05, ANOVA-Dunnet. Conclusion M. alternifolia can reduce bacterial growth and VSCs production and could be used as an alternative to chlorhexidine.

Fundamental modes of new dispersive SH-waves in ...

Indian Academy of Sciences (India)

[3] M Fiebig, V V Pavlov and R V Pisarev, J. Opt. Soc. Am. B 22(1), 96 (2005). [4] T Kimura, Ann. Rev. Condens. Matter Phys. 3(1), 93 (2012). [5] Ch-S Park and Sh Priya, Advances in condensed matter physics (Hindawi Publishing. Corporation, 2012) Vol. 2012, 12 pages. [6] R C Pullar, Prog. Mater. Sci. 57(7), 1191 (2012).

Complex methyl groups dynamics in [(CH3)4P]3Sb2Br9 (PBA) from low to high temperatures by proton spin-lattice relaxation and narrowing of proton NMR spectrum.

Science.gov (United States)

Latanowicz, L; Medycki, W; Jakubas, R

2009-11-01

Molecular dynamics of a polycrystalline sample of [(CH(3))(4)P](3)Sb(2)Br(9) (PBA) has been studied on the basis of the T(1) (24.7 MHz) relaxation time measurement, the proton second moment of NMR and the earlier published T(1) (90 MHz) relaxation times. The study was performed in a wide range of temperatures (30-337 K). The tunnel splitting omega(T) of the methyl groups was estimated as of low frequency (from kHz to few MHz). The proton spin pairs of the methyl group are known to perform a complex internal motion being a resultant of four components. Three of them involve mass transportation over and through the potential barrier and are characterized by the correlation times tau(3) and tau(T)of the jumps over the barrier and tunnel jumps in the threefold potential of the methyl group and tau(iso) the correlation time of isotropic rotation of the whole TMP cation. For tau(3) and tau(iso) the Arrhenius temperature dependence was assumed, while for tau(T)--the Schrödinger one. The fourth motion causes fluctuations of the tunnel splitting frequency, omega(T), and it is related to the lifetime of the methyl spin at the energy level. The correlation function for this fourth motion (tau(omega) correlation time) has been proposed by Müller-Warmuth et al. In this paper a formula for the correlation function and spectral density of the complex motion made of the above-mentioned four components was derived and used in interpretation of the T(1) relaxation time. The second moment of proton NMR line at temperatures below 50K is four times lower than its value for the rigid structure. The three components of the internal motion characterized by tau(T), tau(H), and tau(iso) were proved to reduce the second moment of the NMR line. The tunnel jumps of the methyl group reduce M(2) at almost 0K, the classical jumps over the barrier reduce M(2) in the vicinity of 50K, while the isotropic motion near 150K. Results of the study on the dynamics of CH(3) groups of TMP cation based on

Exploring mechanisms of a tropospheric archetype: CH{sub 3}O{sub 2} + NO

Energy Technology Data Exchange (ETDEWEB)

Launder, Andrew M.; Agarwal, Jay; Schaefer, Henry F., E-mail: ccq@uga.edu [Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States)

2015-12-21

Methylperoxy radical (CH{sub 3}O{sub 2}) and nitric oxide (NO) contribute to the propagation of photochemical smog in the troposphere via the production of methoxy radical (CH{sub 3}O) and nitrogen dioxide (NO{sub 2}). This reaction system also furnishes trace quantities of methyl nitrate (CH{sub 3}ONO{sub 2}), a sink for reactive NO{sub x} species. Here, the CH{sub 3}O{sub 2} + NO reaction is examined with highly reliable coupled-cluster methods. Specifically, equilibrium geometries for the reactants, products, intermediates, and transition states of the ground-state potential energy surface are characterized. Relative reaction enthalpies at 0 K (ΔH{sub 0K}) are reported; these values are comprised of electronic energies extrapolated to the complete basis set limit of CCSDT(Q) and zero-point vibrational energies computed at CCSD(T)/cc-pVTZ. A two-part mechanism involving CH{sub 3}O and NO{sub 2} production followed by radical recombination to CH{sub 3}ONO{sub 2} is determined to be the primary channel for formation of CH{sub 3}ONO{sub 2} under tropospheric conditions. Constrained optimizations of the reaction paths at CCSD(T)/cc-pVTZ suggest that the homolytic bond dissociations involved in this reaction path are barrierless.

Linker length dependent binding of a focal adhesion kinase derived peptide to the Src SH3-SH2 domains.

Science.gov (United States)

Lindfors, Hanna E; Venkata, Bharat Somireddy; Drijfhout, Jan W; Ubbink, Marcellus

2011-02-18

The interaction between a peptide encompassing the SH3 and SH2 binding motifs of focal adhesion kinase (FAK) and the Src SH3-SH2 domains has been investigated with NMR spectroscopy and calorimetry. The binding to both motifs is anti-cooperative. Reduction of the long linker connecting the motifs does not lead to cooperativity. Short linkers that do not allow simultaneous intramolecular binding of the peptide to both motifs cause peptide-mediated dimerisation, even with a linker of only three amino acids. The role of the SH3 binding motif is discussed in view of the independent nature of the SH interactions. Copyright © 2011 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Unimolecular fragrmentations of the radical cation of the high-valent organometal oxide CH3ReO3 and its reactivity with ethylene in the gas phase

Science.gov (United States)

Schröder, Detlef; Herrmann, W. A.; Fischer, Richard W.; Schwarz, Helmut

1992-12-01

The unimolecular chemistry of CH3ReO[radical sign]+3 in the gas phase commences with a methyl migration to' generate CH3 OReO[radical sign]+2. This further undergoes multiple hydrogen migration to the metal centre to generate an intermediate which serves as a precursor for the elimination of both molecular hydrogen and of carbon monoxide. If CH3ReO[radical sign]+3 is reacted with ethylene, inter alia products are observed which point to a competition between an intramolecular metathesis reaction of the ethylene-inserted intermediate CH3CH2CH2ReO3[radical sign]+ and epoxidation of ethylene to generate c-C2H4O.

Application of machine learning methods to histone methylation ChIP-Seq data reveals H4R3me2 globally represses gene expression

Science.gov (United States)

2010-01-01

Background In the last decade, biochemical studies have revealed that epigenetic modifications including histone modifications, histone variants and DNA methylation form a complex network that regulate the state of chromatin and processes that depend on it including transcription and DNA replication. Currently, a large number of these epigenetic modifications are being mapped in a variety of cell lines at different stages of development using high throughput sequencing by members of the ENCODE consortium, the NIH Roadmap Epigenomics Program and the Human Epigenome Project. An extremely promising and underexplored area of research is the application of machine learning methods, which are designed to construct predictive network models, to these large-scale epigenomic data sets. Results Using a ChIP-Seq data set of 20 histone lysine and arginine methylations and histone variant H2A.Z in human CD4+ T-cells, we built predictive models of gene expression as a function of histone modification/variant levels using Multilinear (ML) Regression and Multivariate Adaptive Regression Splines (MARS). Along with extensive crosstalk among the 20 histone methylations, we found H4R3me2 was the most and second most globally repressive histone methylation among the 20 studied in the ML and MARS models, respectively. In support of our finding, a number of experimental studies show that PRMT5-catalyzed symmetric dimethylation of H4R3 is associated with repression of gene expression. This includes a recent study, which demonstrated that H4R3me2 is required for DNMT3A-mediated DNA methylation--a known global repressor of gene expression. Conclusion In stark contrast to univariate analysis of the relationship between H4R3me2 and gene expression levels, our study showed that the regulatory role of some modifications like H4R3me2 is masked by confounding variables, but can be elucidated by multivariate/systems-level approaches. PMID:20653935

Investigation of Structural and Electronic Properties of CH3NH3PbI3 Stabilized by Varying Concentrations of Poly(Methyl Methacrylate (PMMA

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Celline Awino

2017-08-01

Full Text Available Studies have shown that perovskites have a high potential of outdoing silicon based solar cells in terms of solar energy conversion, but their rate of degradation is also high. This study reports on improvement on the stability of CH3NH3PbI3 by passivating it with polymethylmethacrylate (PMMA. Structural and electronic properties of CH3NH3PbI3 stabilized by polymethylmethacrylate (PMMA were investigated by varying concentrations of PMMA in the polymer solutions. Stability tests were performed over a period of time using modulated surface photovoltage (SPV spectroscopy, X-ray diffraction (XRD, and photoluminescence (PL measurements. The XRD patterns confirm the tetragonal structure of the deposited CH3NH3PbI3 for every concentration of PMMA. Furthermore, CH3NH3PbI3 coated with 40 mg/mL of PMMA did not show any impurity phase even after storage in air for 43 days. The Tauc gap (ETauc determined on the basis of the in-phase SPV spectra was found in the range from 1.585 to 1.62 eV for the samples stored during initial days, but shifted towards lower energies as the storage time increased. This can be proposed to be due to different chemical reactions between CH3NH3PbI3/PMMA interfaces and air. PL intensity increased with increasing concentration of PMMA except for the perovskite coated with 40 mg/mL of PMMA. PL quenching in the perovskite coated with 40 mg/mL of PMMA can be interpreted as fast electron transfer towards the substrate in the sample. This study shows that, with an optimum concentration of PMMA coating on CH3NH3PbI3, the lifetime and hence stability on electrical and structural behavior of CH3NH3PbI3 is improved.

Two-state dynamics of the SH3-SH2 tandem of Abl kinase and the allosteric role of the N-cap.

Science.gov (United States)

Corbi-Verge, Carles; Marinelli, Fabrizio; Zafra-Ruano, Ana; Ruiz-Sanz, Javier; Luque, Irene; Faraldo-Gómez, José D

2013-09-03

The regulation and localization of signaling enzymes is often mediated by accessory modular domains, which frequently function in tandems. The ability of these tandems to adopt multiple conformations is as important for proper regulation as the individual domain specificity. A paradigmatic example is Abl, a ubiquitous tyrosine kinase of significant pharmacological interest. SH3 and SH2 domains inhibit Abl by assembling onto the catalytic domain, allosterically clamping it in an inactive state. We investigate the dynamics of this SH3-SH2 tandem, using microsecond all-atom simulations and differential scanning calorimetry. Our results indicate that the Abl tandem is a two-state switch, alternating between the conformation observed in the structure of the autoinhibited enzyme and another configuration that is consistent with existing scattering data for an activated form. Intriguingly, we find that the latter is the most probable when the tandem is disengaged from the catalytic domain. Nevertheless, an amino acid stretch preceding the SH3 domain, the so-called N-cap, reshapes the free-energy landscape of the tandem and favors the interaction of this domain with the SH2-kinase linker, an intermediate step necessary for assembly of the autoinhibited complex. This allosteric effect arises from interactions between N-cap and the SH2 domain and SH3-SH2 connector, which involve a phosphorylation site. We also show that the SH3-SH2 connector plays a determinant role in the assembly equilibrium of Abl, because mutations thereof hinder the engagement of the SH2-kinase linker. These results provide a thermodynamic rationale for the involvement of N-cap and SH3-SH2 connector in Abl regulation and expand our understanding of the principles of modular domain organization.

A Computational Study of Chalcogen-containing H2 X…YF and (CH3 )2 X…YF (X=O, S, Se; Y=F, Cl, H) and Pnicogen-containing H3 X'…YF and (CH3 )3 X'…YF (X'=N, P, As) Complexes.

Science.gov (United States)

McDowell, Sean A C; Buckingham, A David

2018-04-20

A computational study was undertaken for the model complexes H 2 X…YF and (CH 3 ) 2 X…YF (X=O, S, Se; Y=F, Cl, H), and H 3 X'…YF and (CH 3 ) 3 X'…YF (X'=N, P, As), at the MP2/6-311++G(d,p) level of theory. For H 2 X…YF and H 3 X'…YF, noncovalent interactions dominate the binding in order of increasing YF dipole moment, except for H 3 As…F 2 , and possibly H 3 As…ClF. However, for the methyl-substituted complexes (CH 3 ) 2 X…YF and (CH 3 ) 3 X'…YF the binding is especially strong for the complexes containing F 2 , implying significant chemical bonding between the interacting molecules. The relative stability of these complexes can be rationalized by the difference in the electronegativity of the X or X' and Y atoms. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Revealing the properties of defects formed by CH3NH2 molecules in organic-inorganic hybrid perovskite MAPbBr3

Science.gov (United States)

Wang, Ji; Zhang, Ao; Yan, Jun; Li, Dan; Chen, Yunlin

2017-03-01

The properties of defects in organic-inorganic hybrid perovskite are widely studied from the first-principles calculation. However, the defects of methylamine (methylamine = CH3NH2), which would be easily formed during the preparation of the organic-inorganic hybrid perovskite, are rarely investigated. Thermodynamic properties as well as defect states of methylamine embedded MAPbX3 (MA = methyl-ammonium = CH3NH3, X = Br, I) are studied based on first-principles calculations of density functional theory. It was found that there is a shallow defect level near the highest occupied molecular orbital, which induced by the interstitial methylamine defect in MAPbBr3, will lead to an increase of photoluminescence. The calculation results showed that interstitial defect states of methylamine may move deeper due to the interaction between methylamine molecules and methyl-ammonium cations. It was also showed that the interstitial methylamine defect is stable at room temperature, and the defect can be removed easily by annealing.

New approaches to high-throughput structure characterization of SH3 complexes: the example of Myosin-3 and Myosin-5 SH3 domains from S. cerevisiae.

Science.gov (United States)

Musi, Valeria; Birdsall, Berry; Fernandez-Ballester, Gregorio; Guerrini, Remo; Salvatori, Severo; Serrano, Luis; Pastore, Annalisa

2006-04-01

SH3 domains are small protein modules that are involved in protein-protein interactions in several essential metabolic pathways. The availability of the complete genome and the limited number of clearly identifiable SH3 domains make the yeast Saccharomyces cerevisae an ideal proteomic-based model system to investigate the structural rules dictating the SH3-mediated protein interactions and to develop new tools to assist these studies. In the present work, we have determined the solution structure of the SH3 domain from Myo3 and modeled by homology that of the highly homologous Myo5, two myosins implicated in actin polymerization. We have then implemented an integrated approach that makes use of experimental and computational methods to characterize their binding properties. While accommodating their targets in the classical groove, the two domains have selectivity in both orientation and sequence specificity of the target peptides. From our study, we propose a consensus sequence that may provide a useful guideline to identify new natural partners and suggest a strategy of more general applicability that may be of use in other structural proteomic studies.

Methyl halide emissions from greenhouse-grown mangroves

Science.gov (United States)

Manley, Steven L.; Wang, Nun-Yii; Walser, Maggie L.; Cicerone, Ralph J.

2007-01-01

Two mangrove species, Avicennia germinans and Rhizophora mangle, were greenhouse grown for nearly 1.5 years from saplings. A single individual of each species was monitored for the emission of methyl halides from aerial tissue. During the first 240 days, salinity was incrementally increased with the addition of seawater, and was maintained between 18 and 28‰ for the duration of the study. Exponential growth occurred after 180 days. Methyl halide emissions normalized to leaf area were measured throughout the study and varied dramatically. Emission rates normalized to land area (mg m-2 y-1), assuming a LAI = 5, yielded 82 and 29 for CH3Cl, 10 and 1.6 for CH3Br, and 26 and 11 for CH3I, for A. germinans and R. mangle, respectively. From these preliminary determinations, only CH3I emissions emerge as being of possible global atmospheric significance. This study emphasizes the need for field studies of methyl halide emissions from mangrove forests.

Two-state dynamics of the SH3–SH2 tandem of Abl kinase and the allosteric role of the N-cap

Science.gov (United States)

Corbi-Verge, Carles; Marinelli, Fabrizio; Zafra-Ruano, Ana; Ruiz-Sanz, Javier; Luque, Irene; Faraldo-Gómez, José D.

2013-01-01

The regulation and localization of signaling enzymes is often mediated by accessory modular domains, which frequently function in tandems. The ability of these tandems to adopt multiple conformations is as important for proper regulation as the individual domain specificity. A paradigmatic example is Abl, a ubiquitous tyrosine kinase of significant pharmacological interest. SH3 and SH2 domains inhibit Abl by assembling onto the catalytic domain, allosterically clamping it in an inactive state. We investigate the dynamics of this SH3–SH2 tandem, using microsecond all-atom simulations and differential scanning calorimetry. Our results indicate that the Abl tandem is a two-state switch, alternating between the conformation observed in the structure of the autoinhibited enzyme and another configuration that is consistent with existing scattering data for an activated form. Intriguingly, we find that the latter is the most probable when the tandem is disengaged from the catalytic domain. Nevertheless, an amino acid stretch preceding the SH3 domain, the so-called N-cap, reshapes the free-energy landscape of the tandem and favors the interaction of this domain with the SH2-kinase linker, an intermediate step necessary for assembly of the autoinhibited complex. This allosteric effect arises from interactions between N-cap and the SH2 domain and SH3–SH2 connector, which involve a phosphorylation site. We also show that the SH3–SH2 connector plays a determinant role in the assembly equilibrium of Abl, because mutations thereof hinder the engagement of the SH2-kinase linker. These results provide a thermodynamic rationale for the involvement of N-cap and SH3–SH2 connector in Abl regulation and expand our understanding of the principles of modular domain organization. PMID:23959873

Genetic loss of SH2B3 in acute lymphoblastic leukemia.

Science.gov (United States)

Perez-Garcia, Arianne; Ambesi-Impiombato, Alberto; Hadler, Michael; Rigo, Isaura; LeDuc, Charles A; Kelly, Kara; Jalas, Chaim; Paietta, Elisabeth; Racevskis, Janis; Rowe, Jacob M; Tallman, Martin S; Paganin, Maddalena; Basso, Giuseppe; Tong, Wei; Chung, Wendy K; Ferrando, Adolfo A

2013-10-03

The SH2B adaptor protein 3 (SH2B3) gene encodes a negative regulator of cytokine signaling with a critical role in the homeostasis of hematopoietic stem cells and lymphoid progenitors. Here, we report the identification of germline homozygous SH2B3 mutations in 2 siblings affected with developmental delay and autoimmunity, one in whom B-precursor acute lymphoblastic leukemia (ALL) developed. Mechanistically, loss of SH2B3 increases Janus kinase-signal transducer and activator of transcription signaling, promotes lymphoid cell proliferation, and accelerates leukemia development in a mouse model of NOTCH1-induced ALL. Moreover, extended mutation analysis showed homozygous somatic mutations in SH2B3 in 2 of 167 ALLs analyzed. Overall, these results demonstrate a Knudson tumor suppressor role for SH2B3 in the pathogenesis of ALL and highlight a possible link between genetic predisposition factors in the pathogenesis of autoimmunity and leukemogenesis.

Absolute photoionization cross-section of the methyl radical.

Science.gov (United States)

Taatjes, Craig A; Osborn, David L; Selby, Talitha M; Meloni, Giovanni; Fan, Haiyan; Pratt, Stephen T

2008-10-02

The absolute photoionization cross-section of the methyl radical has been measured using two completely independent methods. The CH3 photoionization cross-section was determined relative to that of acetone and methyl vinyl ketone at photon energies of 10.2 and 11.0 eV by using a pulsed laser-photolysis/time-resolved synchrotron photoionization mass spectrometry method. The time-resolved depletion of the acetone or methyl vinyl ketone precursor and the production of methyl radicals following 193 nm photolysis are monitored simultaneously by using time-resolved synchrotron photoionization mass spectrometry. Comparison of the initial methyl signal with the decrease in precursor signal, in combination with previously measured absolute photoionization cross-sections of the precursors, yields the absolute photoionization cross-section of the methyl radical; sigma(CH3)(10.2 eV) = (5.7 +/- 0.9) x 10(-18) cm(2) and sigma(CH3)(11.0 eV) = (6.0 +/- 2.0) x 10(-18) cm(2). The photoionization cross-section for vinyl radical determined by photolysis of methyl vinyl ketone is in good agreement with previous measurements. The methyl radical photoionization cross-section was also independently measured relative to that of the iodine atom by comparison of ionization signals from CH3 and I fragments following 266 nm photolysis of methyl iodide in a molecular-beam ion-imaging apparatus. These measurements gave a cross-section of (5.4 +/- 2.0) x 10(-18) cm(2) at 10.460 eV, (5.5 +/- 2.0) x 10(-18) cm(2) at 10.466 eV, and (4.9 +/- 2.0) x 10(-18) cm(2) at 10.471 eV. The measurements allow relative photoionization efficiency spectra of methyl radical to be placed on an absolute scale and will facilitate quantitative measurements of methyl concentrations by photoionization mass spectrometry.

Free-radical coupling, cleavage, and redox reactions in 60Co γ radiolysis of aqueous methyl acetate. Effects of additives

International Nuclear Information System (INIS)

Bernath, T.; Parsons, G.H. Jr.; Cohen, S.G.

1975-01-01

Reaction of methyl acetate with e - /sub aq/ may lead to CH 3 C(O )OCH 3 (I - ), CH 3 C(OH)OCH 3 (II), and CH 3 CO (IIA), and with .OH and H. to .CH 2 CO 2 CH 3 (III), and to CH 3 CO 2 CH 2 . (IV). Methyl acetate is consumed, G = --3.5, and the loss is decreased by formate which scavenges .H and .OH, and increased by N 2 O which converts e - /sub aq/ to .OH. Hydrogen is formed, G = 1.1, and this is decreased by scavengers for H., and increased by H + which converts e - /sub aq/ to H.. In radiolysis of 0.027 M methyl acetate, 1.5 x 10 22 ev/l., radical combination products are: ethylene diacetate (CH 3 CO 2 CH 2 CH 2 OCOCH 3 ) (EDA), G = 0.48, from IV + IV; methyl β-acetoxypropionate (CH 3 CO 2 CH 2 CH 2 CO 2 CH 3 ) (MAP), G = 0.28, from IV + III; dimethyl succinate (DMS), G = 0.05, from III + III; and a mixture of methyl acetoacetate and acetonyl acetate (MAA and AA), (MAS and AA), G = 0.07. Biacetyl is not observed. β-Mercaptopropionic acid, 0.0005 M, prevents formation of coupling products, as it reduces radicals III and IV, and thiyl radical oxidizes radical II back to methyl acetate. Other sources of .OH, Fenton's reagent and H 2 O 2 -uv, lead to EDA, MAP, and DMS with a high IV/III ratio. H. preferentially attacks acyl C--H; .OH preferentially attacks alkoxyl C--H. Yields of radicals involved in formation of coupling products and acetic acid are estimated: G(II and IIA) = 1.2; G(III) = 1.4; G(IV) = 1.7. Part of the radicals, G approximately 1.6, regenerate methyl acetate by self-repair reduction of IV and III by II. Deuterium is introduced into methyl acetate during radiolysis in D 2 O. (U.S.)

Laboratory rotational spectrum of singly 13C-substituted dimethyl ether up to 1.5 THz and interstellar detection of 13CH_3O12CH_3 - a fruitful interplay between laboratory work and inter

Science.gov (United States)

Koerber, M.; Bisschop, S.; Endres, C.; Lewen, F.; Schlemmer, S.

2011-05-01

Dimethyl ether (CH_3OCH_3) is found in high abundance in star forming regions. However, the interstellar formation process of dimethyl ether still remains unclear up to now. In current gas-grain models gas-phase synthesis via self-methylation of methanol evaporating from grains is discussed in contrast to the surface reaction of CH_3 with successively hydrogenated CO (Garrod & Herbst 2006). An observational test for the formation mechanism has been proposed by Charnley et al. (2004) making use of the 13C fractionation into CO at low temperatures on grains: Comparing the 12C/13C ratio of molecules to the 12CO/13CO ratio allows to distinguish between formation from CO on cold grains and pure gas-phase formation routes. The isotopic ratio of species like dimethyl ether thus can be used as a tracer of the chemical evolution of the observed region. Due to its two methyl groups undergoing large amplitude motions and a relatively strong dipole moment of μ = 1.302 D it shows a strong and dense complex spectrum all over the terahertz region relevant for Herschel and ALMA observations. Accurate transition frequencies are needed to interpret the astronomical spectra. For the main isotopologue extensive data are now available (Endres et al. 2009). However, due to the greatly improved sensitivity of the new observatories isotopic species of abundant molecules like dimethyl ether are appearing in the spectra as well. In this work we present laboratory measurements of singly 13C-substituted dimethyl ether (13CH_3O12CH_3) up to 1.5 THz. More than 1700 transitions of 13CH_3O12CH_3 with rotational quantum numbers up to J = 53 and K = 25 have been analyzed. Based on the laboratory measurements singly 13C-substituted dimethyl ether has been detected for the first time in the spectrum of G327.3-0.6 (Bisschop et al. in prep.) and a preliminary value for the 12C/13C abundance ratio has been determined.

Bimolecular reaction of CH3 + CO in solid p-H2: Infrared absorption of acetyl radical (CH3CO) and CH3-CO complex

Science.gov (United States)

Das, Prasanta; Lee, Yuan-Pern

2014-06-01

We have recorded infrared spectra of acetyl radical (CH3CO) and CH3-CO complex in solid para-hydrogen (p-H2). Upon irradiation at 248 nm of CH3C(O)Cl/p-H2 matrices, CH3CO was identified as the major product; characteristic intense IR absorption features at 2990.3 (ν9), 2989.1 (ν1), 2915.6 (ν2), 1880.5 (ν3), 1419.9 (ν10), 1323.2 (ν5), 836.6 (ν7), and 468.1 (ν8) cm-1 were observed. When CD3C(O)Cl was used, lines of CD3CO at 2246.2 (ν9), 2244.0 (ν1), 1866.1 (ν3), 1046.7 (ν5), 1029.7 (ν4), 1027.5 (ν10), 889.1 (ν6), and 723.8 (ν7) cm-1 appeared. Previous studies characterized only three vibrational modes of CH3CO and one mode of CD3CO in solid Ar. In contrast, upon photolysis of a CH3I/CO/p-H2 matrix with light at 248 nm and subsequent annealing at 5.1 K before re-cooling to 3.2 K, the CH3-CO complex was observed with characteristic IR features at 3165.7, 3164.5, 2150.1, 1397.6, 1396.4, and 613.0 cm-1. The assignments are based on photolytic behavior, observed deuterium isotopic shifts, and a comparison of observed vibrational wavenumbers and relative IR intensities with those predicted with quantum-chemical calculations. This work clearly indicates that CH3CO can be readily produced from photolysis of CH3C(O)Cl because of the diminished cage effect in solid p-H2 but not from the reaction of CH3 + CO because of the reaction barrier. Even though CH3 has nascent kinetic energy greater than 87 kJ mol-1 and internal energy ˜42 kJ mol-1 upon photodissociation of CH3I at 248 nm, its energy was rapidly quenched so that it was unable to overcome the barrier height of ˜27 kJ mol-1 for the formation of CH3CO from the CH3 + CO reaction; a barrierless channel for formation of a CH3-CO complex was observed instead. This rapid quenching poses a limitation in production of free radicals via bimolecular reactions in p-H2.

Lap shear strength and healing capability of self-healing adhesive containing epoxy/mercaptan microcapsules

Energy Technology Data Exchange (ETDEWEB)

Ghazali, Habibah; Ye, Lin [Centre for Advanced Materials Technology (CAMT), School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Zhang, Ming-Qiu [Key Laboratory of Polymeric Composite and Functional Materials of Ministry of Education, Zhongshan University, Guangzhou 510275 (China)

2016-03-09

The aim of this work is to develop a self-healing polymeric adhesive formulation with epoxy/mercaptan microcapsules. Epoxy/mercaptan microcapsules were dispersed into a commercialize two-part epoxy adhesive for developing self-healing epoxy adhesive. The influence of different content of microcapsules on the shear strength and healing capability of epoxy adhesive were investigated using single-lap-joints with average thickness of adhesive layer of about 180 µm. This self-healing adhesive was used in bonding of 5000 series aluminum alloys adherents after mechanical and alkaline cleaning surface treatment. The adhesion strength was measured and presented as function of microcapsules loading. The results indicated that the virgin lap shear strength was increased by about 26% with addition of 3 wt% of self-healing microcapsules. 12% to 28% recovery of the shear strength is achieved after self-healing depending on the microcapsules content. Scanning electron microscopy was used to study fracture surface of the joints. The self-healing adhesives exhibit recovery of both cohesion and adhesion properties with room temperature healing.

Lap shear strength and healing capability of self-healing adhesive containing epoxy/mercaptan microcapsules

International Nuclear Information System (INIS)

Ghazali, Habibah; Ye, Lin; Zhang, Ming-Qiu

2016-01-01

The aim of this work is to develop a self-healing polymeric adhesive formulation with epoxy/mercaptan microcapsules. Epoxy/mercaptan microcapsules were dispersed into a commercialize two-part epoxy adhesive for developing self-healing epoxy adhesive. The influence of different content of microcapsules on the shear strength and healing capability of epoxy adhesive were investigated using single-lap-joints with average thickness of adhesive layer of about 180 µm. This self-healing adhesive was used in bonding of 5000 series aluminum alloys adherents after mechanical and alkaline cleaning surface treatment. The adhesion strength was measured and presented as function of microcapsules loading. The results indicated that the virgin lap shear strength was increased by about 26% with addition of 3 wt% of self-healing microcapsules. 12% to 28% recovery of the shear strength is achieved after self-healing depending on the microcapsules content. Scanning electron microscopy was used to study fracture surface of the joints. The self-healing adhesives exhibit recovery of both cohesion and adhesion properties with room temperature healing.

Atmospheric chemistry of CF3CH2CH2OH

DEFF Research Database (Denmark)

Hurley, Michael D.; Misner, Jessica A.; Ball, James C.

2005-01-01

Relative rate techniques were used to study the kinetics of the reactions of Cl atoms and OH radicals with CF3CH2C(O)H and CF3CH2CH2OH in 700 Torr of N-2 or air diluent at 296 2 K. The rate constants determined were k(Cl+CF3CH2C(O)H) = (1.81 +/- 0.27) x 10(-11), k(OH+CF3CH2C(O)H) = (2.57 +/- 0.44...

Decreased viscosity of rat-liver DNA treated by 3'-methyl-4-dimethylaminoazobenzene, detected with a new viscometric approach.

Science.gov (United States)

Parodi, S; Balbi, C; Taningher, M; Pala, M; Russo, P; Abelmoschi, M L; Santi, L

1982-11-01

DNA damage induced in vivo by 3'-methyl-4-dimethylaminoazobenzene (3'CH3DAB) was investigated with 2 differently sensitive techniques: the alkaline elution assay and the viscometric measurement of DNA damage. 3'CH3DAB appeared to be falsely negative with the alkaline elution assay, whereas with the viscometric approach, which is about 30-50 times more sensitive, it appeared positive, and the DNA damage was dose-dependent.

Ab Initio Chemical Kinetics for the CH3 + O((3)P) Reaction and Related Isomerization-Decomposition of CH3O and CH2OH Radicals.

Science.gov (United States)

Xu, Z F; Raghunath, P; Lin, M C

2015-07-16

The kinetics and mechanism of the CH3 + O reaction and related isomerization-decomposition of CH3O and CH2OH radicals have been studied by ab initio molecular orbital theory based on the CCSD(T)/aug-cc-pVTZ//CCSD/aug-cc-pVTZ, CCSD/aug-cc-pVDZ, and G2M//B3LYP/6-311+G(3df,2p) levels of theory. The predicted potential energy surface of the CH3 + O reaction shows that the CHO + H2 products can be directly generated from CH3O by the TS3 → LM1 → TS7 → LM2 → TS4 path, in which both LM1 and LM2 are very loose and TS7 is roaming-like. The result for the CH2O + H reaction shows that there are three low-energy barrier processes including CH2O + H → CHO + H2 via H-abstraction and CH2O + H → CH2OH and CH2O + H → CH3O by addition reactions. The predicted enthalpies of formation of the CH2OH and CH3O radicals at 0 K are in good agreement with available experimental data. Furthermore, the rate constants for the forward and some key reverse reactions have been predicted at 200-3000 K under various pressures. Based on the new reaction pathway for CH3 + O, the rate constants for the CH2O + H and CHO + H2 reactions were predicted with the microcanonical variational transition-state/Rice-Ramsperger-Kassel-Marcus (VTST/RRKM) theory. The predicted total and individual product branching ratios (i.e., CO versus CH2O) are in good agreement with experimental data. The rate constant for the hydrogen abstraction reaction of CH2O + H has been calculated by the canonical variational transition-state theory with quantum tunneling and small-curvature corrections to be k(CH2O + H → CHO + H2) = 2.28 × 10(-19) T(2.65) exp(-766.5/T) cm(3) molecule(-1) s(-1) for the 200-3000 K temperature range. The rate constants for the addition giving CH3O and CH2OH and the decomposition of the two radicals have been calculated by the microcanonical RRKM theory with the time-dependent master equation solution of the multiple quantum well system in the 200-3000 K temperature range at 1 Torr to

Formation and Atmosphere of Complex Organic Molecules of the HH 212 Protostellar Disk

Energy Technology Data Exchange (ETDEWEB)

Lee, Chin-Fei; Ho, Paul T. P.; Hirano, Naomi; Shang, Hsien [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 106, Taiwan (China); Li, Zhi-Yun [Astronomy Department, University of Virginia, Charlottesville, VA 22904 (United States); Zhang, Qizhou, E-mail: cflee@asiaa.sinica.edu.tw [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2017-07-01

HH 212 is a nearby (400 pc) Class 0 protostellar system recently found to host a “hamburger”-shaped dusty disk with a radius of ∼60 au, deeply embedded in an infalling-rotating flattened envelope. We have spatially resolved this envelope-disk system with the Atacama Large Millimeter/submillimeter Array at up to ∼16 au (0.″04) resolution. The envelope is detected in HCO{sup +} J = 4–3 down to the dusty disk. Complex organic molecules (COMs) and doubly deuterated formaldehyde (D{sub 2}CO) are detected above and below the dusty disk within ∼40 au of the central protostar. The COMs are methanol (CH{sub 3}OH), deuterated methanol (CH{sub 2}DOH), methyl mercaptan (CH{sub 3}SH), and formamide (NH{sub 2}CHO, a prebiotic precursor). We have modeled the gas kinematics in HCO{sup +} and COMs and found a centrifugal barrier (CB) at a radius of ∼44 au, within which a Keplerian rotating disk is formed. This indicates that HCO{sup +} traces the infalling-rotating envelope down to the CB and COMs trace the atmosphere of a Keplerian rotating disk within the CB. The COMs are spatially resolved for the first time, both radially and vertically, in the atmosphere of a disk in the earliest, Class 0 phase of star formation. Our spatially resolved observations of COMs favor their formation in the disk rather than a rapidly infalling (warm) inner envelope. The abundances and spatial distributions of the COMs provide strong constraints on models of their formation and transport in low-mass star formation.

Rate Constants for the Reactions of OH with CH(sub 3)Cl, CH(sub 2) C1(sub 2), CHC1(sub 3)and CH(sub 3)Br

Science.gov (United States)

Hsu, H-J.; DeMore, W.

1994-01-01

Rate constants for the reactions of OH with CH3C1, CH2Cl2, CHCl3 and CH3Br have been measured by a relative rate technique in which the reaction rate of each compound was compared to that of HFC-152a (CH3CHF2)and for CH2Cl2, HFC-161 (CH3CH2F).

Methanesulfonates of high-valent metals. Syntheses and structural features of MoO_2(CH_3SO_3)_2, UO_2(CH_3SO_3)_2, ReO_3(CH_3SO_3), VO(CH_3SO_3)_2, and V_2O_3(CH_3SO_3)_4 and their thermal decomposition under N_2 and O_2 atmosphere

International Nuclear Information System (INIS)

Betke, Ulf; Neuschulz, Kai; Wickleder, Mathias S.

2011-01-01

Oxide methanesulfonates of Mo, U, Re, and V have been prepared by reaction of MoO_3, UO_2(CH_3COO)_2.2 H_2O, Re_2O_7(H_2O)_2, and V_2O_5 with CH_3SO_3H or mixtures thereof with its anhydride. These compounds are the first examples of solvent-free oxide methanesulfonates of these elements. MoO_2(CH_3SO_3)_2 (Pbca, a=1487.05(4), b=752.55(2), c=1549.61(5) pm, V=1.73414(9) nm"3, Z=8) contains [MoO_2] moieties connected by [CH_3SO_3] ions to form layers parallel to (100). UO_2(CH_3SO_3)_2 (P2_1/c, a=1320.4(1), b=1014.41(6), c=1533.7(1) pm, β=112.80(1) "c"i"r"c"l"e, V=1.8937(3) nm"3, Z=8) consists of linear UO_2"2"+ ions coordinated by five [CH_3SO_3] ions, forming a layer structure. VO(CH_3SO_3)_2 (P2_1/c, a=1136.5(1), b=869.87(7), c=915.5(1) pm, β=113.66(1) "c"i"r"c"l"e, V=0.8290(2) nm"3, Z=4) contains [VO] units connected by methanesulfonate anions to form corrugated layers parallel to (100). In ReO_3(CH_3SO_3) (P anti 1, a=574.0(1), b=1279.6(3), c=1641.9(3) pm, α=102.08(2), β=96.11(2), γ=99.04(2) "c"i"r"c"l"e, V=1.1523(4) nm"3, Z=8) a chain structure exhibiting infinite O-[ReO_2]-O-[ReO_2]-O chains is formed. Each [ReO_2]-O-[ReO_2] unit is coordinated by two bidentate [CH_3SO_3] ions. V_2O_3(CH_3SO_3)_4 (I2/a, a=1645.2(3), b=583.1(1), c=1670.2(3) pm, β=102.58(3), V=1.5637(5) pm"3, Z=4) adopts a chain structure, too, but contains discrete [VO]-O-[VO] moieties, each coordinated by two bidentate [CH_3SO_3] ligands. Additional methanesulfonate ions connect the [V_2O_3] groups along [001]. Thermal decomposition of the compounds was monitored under N_2 and O_2 atmosphere by thermogravimetric/differential thermal analysis and XRD measurements. Under N_2 the decomposition proceeds with reduction of the metal leading to the oxides MoO_2, U_3O_7, V_4O_7, and VO_2; for MoO_2(CH_3SO_3)_2, a small amount of MoS_2 is formed. If the thermal decomposition is carried out in a atmosphere of O_2 the oxides MoO_3 and V_2O_5 are formed. (Copyright copyright 2011 WILEY-VCH Verlag

Inhibition of Ps Formation in Benzene and Cyclohexane by CH3CI and CH3Br

DEFF Research Database (Denmark)

Wikander, G.; Mogensen, O. E.; Pedersen, Niels Jørgen

1983-01-01

Positron-annihilation lifetime spectra have been measured for mixtures of CH3Cl and CH3Br in cyclohexane and of CH3Cl in benzene. The ortho-positronium (Ps) yield decreased monotonically from 38% and 43% in cyclohexane and benzene respectively to 11% in pure CH3Cl and 6% in pure CH3Br. The strength......− anions to form Ps. while it forms a bound state with the halides. X−. CH3Cl was a roughly three times weaker Ps inhibitor in benzene than in cyclohexane, which shows that CH3Cl− does not dechlorinate in times comparable to or shorter than 400–500 ps in benzene. An improved model for the explanation of Ps...

Distinct ubiquitin binding modes exhibited by SH3 domains: molecular determinants and functional implications.

Directory of Open Access Journals (Sweden)

Jose L Ortega Roldan

Full Text Available SH3 domains constitute a new type of ubiquitin-binding domains. We previously showed that the third SH3 domain (SH3-C of CD2AP binds ubiquitin in an alternative orientation. We have determined the structure of the complex between first CD2AP SH3 domain and ubiquitin and performed a structural and mutational analysis to decipher the determinants of the SH3-C binding mode to ubiquitin. We found that the Phe-to-Tyr mutation in CD2AP and in the homologous CIN85 SH3-C domain does not abrogate ubiquitin binding, in contrast to previous hypothesis and our findings for the first two CD2AP SH3 domains. The similar alternative binding mode of the SH3-C domains of these related adaptor proteins is characterised by a higher affinity to C-terminal extended ubiquitin molecules. We conclude that CD2AP/CIN85 SH3-C domain interaction with ubiquitin constitutes a new ubiquitin-binding mode involved in a different cellular function and thus changes the previously established mechanism of EGF-dependent CD2AP/CIN85 mono-ubiquitination.

The methylcobalt(III) complex of a tetrapodal pentadentate amine ligand, 2,6-bis(1′,3′-diamino-2′-methyl-prop-2′-yl)pyridine

DEFF Research Database (Denmark)

Grohmann, Andreas; Heinemann, Frank W; Kofod, Pauli

1999-01-01

The pentaamine methylcobalt(III) compound [Co(pyN4)(CH3)](NO3)2 (pyN4=2,6-bis(1′,3′-diamino-2′-methyl-prop-2′-yl)pyridine) has been synthesised from [Co(NH3)5(CH3)](NO3)2 and pyN4 by ligand exchange, and characterised by IR, 1H, 13C and 59Co NMR spectroscopy as well as elemental analysis. The str......The pentaamine methylcobalt(III) compound [Co(pyN4)(CH3)](NO3)2 (pyN4=2,6-bis(1′,3′-diamino-2′-methyl-prop-2′-yl)pyridine) has been synthesised from [Co(NH3)5(CH3)](NO3)2 and pyN4 by ligand exchange, and characterised by IR, 1H, 13C and 59Co NMR spectroscopy as well as elemental analysis...... nitrogen atom, while the four equivalent primary amino groups take the equatorial positions. The other axial position, trans to the pyridine ring, is occupied by the methyl group. The Co–Npy bond length of 2.018(2) Å is significantly elongated compared with other cobalt(III) complexes of the pyN4 ligand...

Methylation of WTH3, a possible drug resistant gene, inhibits p53 regulated expression

International Nuclear Information System (INIS)

Tian, Kegui; Wang, Yuezeng; Huang, Yu; Sun, Boqiao; Li, Yuxin; Xu, Haopeng

2008-01-01

Previous results showed that over-expression of the WTH3 gene in MDR cells reduced MDR1 gene expression and converted their resistance to sensitivity to various anticancer drugs. In addition, the WTH3 gene promoter was hypermethylated in the MCF7/AdrR cell line and primary drug resistant breast cancer epithelial cells. WTH3 was also found to be directly targeted and up regulated by the p53 gene. Furthermore, over expression of the WTH3 gene promoted the apoptotic phenotype in various host cells. To further confirm WTH3's drug resistant related characteristics, we recently employed the small hairpin RNA (shRNA) strategy to knockdown its expression in HEK293 cells. In addition, since the WTH3 promoter's p53-binding site was located in a CpG island that was targeted by methylation, we were interested in testing the possible effect this epigenetic modification had on the p53 transcription factor relative to WTH3 expression. To do so, the in vitro methylation method was utilized to examine the p53 transgene's influence on either the methylated or non-methylated WTH3 promoter. The results generated from the gene knockdown strategy showed that reduction of WTH3 expression increased MDR1 expression and elevated resistance to Doxorubicin as compared to the original control cells. Data produced from the methylation studies demonstrated that DNA methylation adversely affected the positive impact of p53 on WTH3 promoter activity. Taken together, our studies provided further evidence that WTH3 played an important role in MDR development and revealed one of its transcription regulatory mechanisms, DNA methylation, which antagonized p53's positive impact on WTH3 expression

Relativistic GW calculations on CH3NH3PbI3 and CH3NH3SnI3 perovskites for solar cell applications.

Science.gov (United States)

Umari, Paolo; Mosconi, Edoardo; De Angelis, Filippo

2014-03-26

Hybrid AMX3 perovskites (A = Cs, CH3NH3; M = Sn, Pb; X = halide) have revolutionized the scenario of emerging photovoltaic technologies, with very recent results demonstrating 15% efficient solar cells. The CH3NH3PbI3/MAPb(I(1-x)Cl(x))3 perovskites have dominated the field, while the similar CH3NH3SnI3 has not been exploited for photovoltaic applications. Replacement of Pb by Sn would facilitate the large uptake of perovskite-based photovoltaics. Despite the extremely fast progress, the materials electronic properties which are key to the photovoltaic performance are relatively little understood. Density Functional Theory electronic structure methods have so far delivered an unbalanced description of Pb- and Sn-based perovskites. Here we develop an effective GW method incorporating spin-orbit coupling which allows us to accurately model the electronic, optical and transport properties of CH3NH3SnI3 and CH3NH3PbI3, opening the way to new materials design. The different CH3NH3SnI3 and CH3NH3PbI3 electronic properties are discussed in light of their exploitation for solar cells, and found to be dominantly due to relativistic effects. These effects stabilize the CH3NH3PbI3 material towards oxidation, by inducing a deeper valence band edge. Relativistic effects, however, also increase the material band-gap compared to CH3NH3SnI3, due to the valence band energy downshift (~0.7 eV) being only partly compensated by the conduction band downshift (~0.2 eV).

The influence of n-butyl mercaptan on acrylic compounds obtained winder γ-gamma radiation

International Nuclear Information System (INIS)

Ribeiro, Marcos S.; Parra, Duclerc F.; Lugao, Ademar B.

2013-01-01

The chain transfer agents play a key role in the production of polymers, as they allow better control of their molecular weight, among other functions. For this reason we performed this study to perform an analysis on the influence of n-butyl mercaptan in the reaction of compounds of ethyl methacrylate by varying the density and shrinkage of the samples. In the present study can be seen that n-butyl mercaptan, acts as transfer agent, which influences the reaction kinetics of composite acrylic, since it presence in the compound increased average density and contraction average. It is also possible to minimize the variability of the compound density, even if they are altered. Final products with improved properties homogeneously could be obtained. (author)

Differential sensitivity of Src-family kinases to activation by SH3 domain displacement.

Directory of Open Access Journals (Sweden)

Jamie A Moroco

Full Text Available Src-family kinases (SFKs are non-receptor protein-tyrosine kinases involved in a variety of signaling pathways in virtually every cell type. The SFKs share a common negative regulatory mechanism that involves intramolecular interactions of the SH3 domain with the PPII helix formed by the SH2-kinase linker as well as the SH2 domain with a conserved phosphotyrosine residue in the C-terminal tail. Growing evidence suggests that individual SFKs may exhibit distinct activation mechanisms dictated by the relative strengths of these intramolecular interactions. To elucidate the role of the SH3:linker interaction in the regulation of individual SFKs, we used a synthetic SH3 domain-binding peptide (VSL12 to probe the sensitivity of downregulated c-Src, Hck, Lyn and Fyn to SH3-based activation in a kinetic kinase assay. All four SFKs responded to VSL12 binding with enhanced kinase activity, demonstrating a conserved role for SH3:linker interaction in the control of catalytic function. However, the sensitivity and extent of SH3-based activation varied over a wide range. In addition, autophosphorylation of the activation loops of c-Src and Hck did not override regulatory control by SH3:linker displacement, demonstrating that these modes of activation are independent. Our results show that despite the similarity of their downregulated conformations, individual Src-family members show diverse responses to activation by domain displacement which may reflect their adaptation to specific signaling environments in vivo.

Micro-syntheses for the use of carbon 13 or carbon 14. Micro-preparations of methyl alcohol, methyl iodide, and sodium acetate labeled in the methyl group

International Nuclear Information System (INIS)

Baret, C.; Pichat, L.

1951-11-01

Apparatus and technique are described in detail for (1) reduction of CO 2 to CH 3 OH with LiAlH 4 , (2) conversion of the methanol to CH 3 I by HI, (3) formation of the Mg Grignard reagent, and (4) addition of inactive CO 2 to form CH 3 COOH. All these operations have been carried out on 0.005 moles. Methyl-labeled Na acetate has been prepared in 67% yield based on the Ba 14 CO 3 used as starting material. (author) [fr

H2S and mercaptans in the air in the Molve gas field

International Nuclear Information System (INIS)

Vadjic, V.; Tomic, M.

1995-01-01

During the processing and refining of natural gas the working areas and ambient air can be polluted by emission of specific pollutants. The natural gas from gas and gas-condensate fields Molve, Stari Gradac and Kalinovac near Bjelovar in northern Croatia contains high levels of hydrogen sulphide and mercaptans. At the central gas station located in the gas field Molve the sour gas from all fields is collected and cleaned by absorption of sulphur compounds in K 2 CO 3 solution before emission to the atmosphere

A randomized double blind crossover placebo-controlled clinical trial to assess the effects of a mouthwash containing chlorine dioxide on oral malodor

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Yokoyama Sayaka

2008-12-01

Full Text Available Abstract Background Previous research has shown the oxidizing properties and microbiological efficacies of chlorine dioxide (ClO2, however, its clinical efficacies on oral malodor have been evaluated only with organoleptic measurements (OM or sulphide monitors. No clinical studies have investigated the inhibitory effects of ClO2 on volatile sulfur compounds (VSCs using gas chromatography (GC. The aim of this study was to assess the inhibitory effects of a mouthwash containing ClO2 on morning oral malodor using OM and GC. Methods A randomized, double blind, crossover, placebo-controlled clinical trial was conducted among 15 healthy male volunteers, who were divided into 2 groups. In the first test phase, the group 1 subjects (N = 8 were instructed to rinse with the experimental mouthwash containing ClO2, and those in group 2 (N = 7 to rinse with the placebo mouthwash without ClO2. In the second test, phase after a one week washout period, each group used the opposite mouthwash. Oral malodor was evaluated before rinsing, right after rinsing and every 30 minutes up to 4 hours with OM, and concentrations of hydrogen sulfide (H2S, methyl mercaptan (CH3SH and dimethyl sulfide ((CH32S, the main VSCs of human oral malodor, were evaluated with GC. Results The baseline oral condition in the subjects in the 2 groups did not differ significantly. The mouthwash containing ClO2 improved morning bad breath according to OM and reduced concentrations of H2S, CH3SH and (CH32S according to GC up to 4 hours after rinsing. OM scores with ClO2 were significantly lower than those without ClO2 at all examination times. Significant reductions in the concentrations of the three kinds of VSCs measured by GC were also evident at all examination times. The concentrations of the three gases with ClO2 were significantly lower than those without ClO2 at most examination times. Conclusion In this explorative study, ClO2 mouthwash was effective at reducing morning malodor for 4

Effects of a mouthwash with chlorine dioxide on oral malodor and salivary bacteria: a randomized placebo-controlled 7-day trial

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Ohnuki Mari

2010-02-01

Full Text Available Abstract Background Previous research has shown the oxidizing properties and microbiological efficacies of chlorine dioxide (ClO2. Its clinical efficacies on oral malodor have been evaluated and reported only in short duration trials, moreover, no clinical studies have investigated its microbiological efficacies on periodontal and malodorous bacteria. Thus, the aim of this study was to assess the inhibitory effects of a mouthwash containing ClO2 used for 7 days on morning oral malodor and on salivary periodontal and malodorous bacteria. Methods/Design A randomized, double blind, crossover, placebo-controlled trial was conducted among 15 healthy male volunteers, who were divided into 2 groups. Subjects were instructed to rinse with the experimental mouthwash containing ClO2 or the placebo mouthwash, without ClO2, twice per day for 7 days. After a one week washout period, each group then used the opposite mouthwash for 7 days. At baseline and after 7 days, oral malodor was evaluated with Organoleptic measurement (OM, and analyzed the concentrations of hydrogen sulfide (H2S, methyl mercaptan (CH3SH and dimethyl sulfide ((CH32S, the main VSCs of human oral malodor, were assessed by gas chromatography (GC. Clinical outcome variables included plaque and gingival indices, and tongue coating index. The samples of saliva were microbiologically investigated. Quantitative and qualitative analyses were performed using the polymerase chain reaction-Invader method. Results and Discussion The baseline oral condition in healthy subjects in the 2 groups did not differ significantly. After rinsing with the mouthwash containing ClO2 for 7 days, morning bad breath decreased as measured by the OM and reduced the concentrations of H2S, CH3SH and (CH32S measured by GC, were found. Moreover ClO2 mouthwash used over a 7-day period appeared effective in reducing plaque, tongue coating accumulation and the counts of Fusobacterium nucleatum in saliva. Future research is

Ultrasonic irradiation-promoted one-pot synthesis of CH3NH3PbBr3 quantum dots without using flammable CH3NH2 precursor

Science.gov (United States)

Jiang, Han; Wang, Chunlei; Lv, Changgui; Xu, Shuhong; Zhu, Li; Zhang, Ruohu; Cui, Yiping

2017-02-01

At present, the CH3NH3PbBr3 quantum dots (QDs) reported in the literature usually contain two synthesis steps: the initial preparation of CH3NH3Br via the reaction of flammable CH3NH2 and HBr, together with the subsequent formation of CH3NH3PbBr3 QDs. To avoid the use of dangerous CH3NH2, this work develops a novel one-pot method for synthesizing CH3NH3PbBr3 QDs using safe and commercially available reactants (CH3NH3Cl, KBr and PbCl2). It is found that ultrasonic treatment plays a key role during the synthesis of CH3NH3PbBr3 QDs. Without ultrasonic irradiation, it is not possible to synthesize CH3NH3PbBr3 QDs under heating or vigorous stirring. Aliquots of samples taken at different ultrasonic irradiation time intervals show a time-dependent redshift in the emission wavelength. This suggests the formation of CH3NH3PbCl3 QDs first, followed by the formation of CH3NH3PbBr3 QDs through ultrasonically promoted halide exchange. Moreover, mixed CH3NH3PbCl x Br3-x QDs with a tunable emission wavelength can also be prepared through this one-pot method by controlling the ultrasonic irradiation time. In comparison to the previous two-step method, the current one-pot method is simpler, less time-consuming and does not use flammable CH3NH2. The as-prepared CH3NH3PbBr3 QDs show a comparable photoluminescence (PL) quantum yield (QY) to that of the literature. What is more, the ultrasonic time-controlled emission wavelength of CH3NH3PbCl x Br3-x QDs also provides an alternative way of tuning QD emission to the traditional way of controlling the halide ratios.

CH3Br adsorption on MgO/Mo ultrathin films: A DFT study

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Cipriano, Luis A.; Tosoni, Sergio; Pacchioni, Gianfranco

2018-06-01

The adsorption of methyl bromide on MgO ultrathin films supported on Mo(100) was studied by means of density functional theory calculations, in comparison to the MgO(100) and Mo(100) surfaces. The adsorption energy and geometry were shown to depend on the thickness of the supported oxide film. MgO films as thick as 2ML (or more) display adsorptive properties similar to MgO(100), i.e. the adsorption of CH3Br is mostly due to dispersion and the molecule lies in a tilted geometry almost parallel to the surface. The CH3Br HOMO-LUMO gap is almost unaltered with respect to the gas phase. On metallic Mo(100) surfaces the bonding is completely different with the CH3Br molecule strongly bound and the C-Br bond axis almost vertical with respect to the metal surface. The MgO monolayer supported on Mo exhibits somehow intermediate properties: the tilt angle is larger and the bonding is stronger than on MgO(100), due to the effect of the supporting metal. In this case, a small reduction of the HOMO-LUMO gap of the adsorbed molecule is reported. The results help to rationalize the observed behavior in photodissociation of CH3Br supported on different substrates.

Activation of methane by zinc: gas-phase synthesis, structure, and bonding of HZnCH3.

Science.gov (United States)

Flory, Michael A; Apponi, Aldo J; Zack, Lindsay N; Ziurys, Lucy M

2010-12-08

The methylzinc hydride molecule, HZnCH3, has been observed in the gas phase for the first time in the monomeric form using high-resolution spectroscopic techniques. The molecule was synthesized by two methods: the reaction of dimethylzinc with hydrogen gas and methane in an AC discharge and the reaction of zinc vapor produced in a Broida-type oven with methane in a DC discharge. HZnCH3 was identified on the basis of its pure rotational spectrum, which was recorded using millimeter/submillimeter direct-absorption and Fourier transform microwave techniques over the frequency ranges 332-516 GHz and 18-41 GHz, respectively. Multiple rotational transitions were measured for this molecule in seven isotopic variants. K-ladder structure was clearly present in all of the spectra, indicating a molecule with C3v symmetry and a (1)A1 ground electronic state. Extensive quadrupole hyperfine structure arising from the (67)Zn nucleus was observed for the H(67)ZnCH3 species, suggesting covalent bonding to the zinc atom. From the multiple isotopic substitutions, a precise structure for HZnCH3 has been determined. The influence of the axial hydrogen atom slightly distorts the methyl group but stabilizes the Zn-C bond. This study suggests that HZnCH3 can be formed through the oxidative addition of zinc to methane in the gas phase under certain conditions. HZnCH3 is the first metal-methane insertion complex to be structurally characterized.

21 CFR 172.872 - Methyl ethyl cellulose.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Methyl ethyl cellulose. 172.872 Section 172.872... CONSUMPTION Multipurpose Additives § 172.872 Methyl ethyl cellulose. The food additive methyl ethyl cellulose... a cellulose ether having the general formula [C6H(10 -x-y)O5(CH3)x(C2H5)y]n, where x is the number...

Methyl bromide residues in fumigated cocoa beans

International Nuclear Information System (INIS)

Adomako, D.

1975-01-01

The 14 C activity in unroasted [ 14 C]-methyl bromide fumigated cocoa beans was used to study the fate and persistence of CH 3 Br in the stored beans. About 70% of the residues occurred in the shells. Unchanged CH 3 Br could not be detected, all the sorbed CH 3 Br having reacted with bean constituents apparently to form 14 C-methylated derivatives and inorganic bromide. No 14 C activity was found in the lipid fraction. Roasting decreased the bound (non-volatile) residues, with corresponding changes in the activities and amounts of free sugars, free and protein amino acids. Roasted nibs and shells showed a two-fold increase in the volatile fraction of the 14 C residue. This fraction may be related to the volatile aroma compounds formed by Maillard-type reactions. (author)

Micro-syntheses for the use of carbon 13 or carbon 14. Micro-preparations of methyl alcohol, methyl iodide, and sodium acetate labeled in the methyl group; Microsyntheses pour l'emploi de carbone 13 ou de carbone 14. Micropreparations d'alcool methylique, d'iodure de methyle et d'acetate de sodium marque sur le groupement methyle

Energy Technology Data Exchange (ETDEWEB)

Baret, C; Pichat, L

1951-11-01

Apparatus and technique are described in detail for (1) reduction of CO{sub 2} to CH{sub 3}OH with LiAlH{sub 4}, (2) conversion of the methanol to CH{sub 3}I by HI, (3) formation of the Mg Grignard reagent, and (4) addition of inactive CO{sub 2} to form CH{sub 3}COOH. All these operations have been carried out on 0.005 moles. Methyl-labeled Na acetate has been prepared in 67% yield based on the Ba{sup 14}CO{sub 3} used as starting material. (author) [French] Description detaillee d'une technique deja connue pour la reduction du gaz carbonique en alcool methylique par LiAlH{sub 4}. Conversion du methanol en iodure de methyle. Ce dernier transforme en reactif de Grigard, et carbonate, fournit de l'acide acetique. Toutes ces operations on ete effectuees sur 5 x 10{sup -3} moles. La methode a ete appliquee a la synthese d'acetate de sodium marque par le groupement methyle par {sup 14}C avec un rendement global de 67% base sur le carbonate de baryum radioactif mis en oeuvre. (auteurs)

Bayesian modeling of the yeast SH3 domain interactome predicts spatiotemporal dynamics of endocytosis proteins.

Directory of Open Access Journals (Sweden)

Raffi Tonikian

2009-10-01

Full Text Available SH3 domains are peptide recognition modules that mediate the assembly of diverse biological complexes. We scanned billions of phage-displayed peptides to map the binding specificities of the SH3 domain family in the budding yeast, Saccharomyces cerevisiae. Although most of the SH3 domains fall into the canonical classes I and II, each domain utilizes distinct features of its cognate ligands to achieve binding selectivity. Furthermore, we uncovered several SH3 domains with specificity profiles that clearly deviate from the two canonical classes. In conjunction with phage display, we used yeast two-hybrid and peptide array screening to independently identify SH3 domain binding partners. The results from the three complementary techniques were integrated using a Bayesian algorithm to generate a high-confidence yeast SH3 domain interaction map. The interaction map was enriched for proteins involved in endocytosis, revealing a set of SH3-mediated interactions that underlie formation of protein complexes essential to this biological pathway. We used the SH3 domain interaction network to predict the dynamic localization of several previously uncharacterized endocytic proteins, and our analysis suggests a novel role for the SH3 domains of Lsb3p and Lsb4p as hubs that recruit and assemble several endocytic complexes.

Kinetic isotope effects in the gas phase reactions of OH and Cl with CH3Cl, CD3Cl, and 13CH3Cl

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A. A. Gola

2005-01-01

Full Text Available The kinetic isotope effects in the reactions of CH3Cl, 13CH3Cl and CD3Cl with OH radicals and Cl atoms were studied in relative rate experiments at 298±2 K and 1013±10 mbar. The reactions were carried out in a smog chamber using long path FTIR detection and the spectroscopic data analyzed employing a non-linear least squares spectral fitting method using measured high-resolution infrared spectra as well as absorption cross sections from the HITRAN database. The reaction rates of 13CH3Cl and CD3Cl with OH and Cl were determined relative to CH3Cl as: kOH+CH3ClkOH+CH3Cl/kOH+13CH3Cl}kOH+13CH3Cl=1.059±0.008, kOH+CH3ClkOH+CH3Cl/kOH+CD3ClkOH+CD3Cl=3.9±0.4, kCl+CH3ClkCl+CH3Cl/kCl+13CH3ClkCl+13CH3Cl =1.070±0.010 and kCl+CH3ClkCl+CH3Cl/kCl+CD3ClkCl+CD3Cl=4.91±0.07. The uncertainties given are 2σ from the statistical analyses and do not include possible systematic errors. The unexpectedly large 13C kinetic isotope effect in the OH reaction of CH3Cl has important implications for the global emission inventory of CH3Cl.

Dissociative resonance electron capture in methylmercaptane and methylmercaptane-d3

International Nuclear Information System (INIS)

Sugiura, Toshio; Arakawa, Kazuo.

1975-01-01

The formation of negative ions by electron impact of methylmercaptane and methylmercaptane-3 3 has been investigated as a function of the electron energy. Appearance potentials, energies of resonance peaks, full widths of half maxima in resonance peak and relative formation cross sections have been determined about the negative ions of H - , D - , CH 3 S - , CD 3 S - , SH - , S - , CH 2 - , CD 2 - , Ch - and CD - . The dissociation energy of S-H bond and an electron affinity of CH 3 S radical have been determined as 4.7 +- 0.1 and 3.18 +- 0.2 eV, respectively. (auth.)

Isomerization and dissociation in competition: the two-component dissociation rates of methyl acetate ions

Science.gov (United States)

Mazyar, Oleg A.; Mayer, Paul M.; Baer, Tomas

1997-11-01

Threshold photoelectron-photoion coincidence (TPEPICO) spectroscopy has been used to investigate the unimolecular chemistry of metastable methyl acetate ions, CH3COOCH3.+. The rate of molecular ion fragmentation with the loss of CH3O. and CH2OH radicals as a function of ion internal energy was obtained from the coincidence data and used in conjunction with Rice-Ramsperger-Kassel-Markus and ab initio molecular orbital calculations to model the dissociation/isomerization mechanism of the methyl acetate ion (A). The data were found to be consistent with the mechanism involving a hydrogen-bridged complex CH3CO[middle dot][middle dot][middle dot]H[middle dot][middle dot][middle dot]OCH2.+(E) as the direct precursor of the observed fragments CH3CO+ and CH2OH.. The two-component decay rates were modeled with a three-well-two-product potential energy surface including the distonic ion CH3C(OH)OCH2.+(B) and enol isomer CH2C(OH)OCH3.+(C), which are formed from the methyl acetate ion by two consecutive [1,4]-hydrogen shifts. The 0 K heats of formation of isomers B and C as well as transition states TSAB, TSBC, and TSBE (relative to isomer A) were calculated from Rice-Ramsperger-Kassel-Markus (RRKM) theory.

Searching for trans ethyl methyl ether in Orion KL.

Science.gov (United States)

Tercero, B; Cernicharo, J; López, A; Brouillet, N; Kolesniková, L; Motiyenko, R A; Margulès, L; Alonso, J L; Guillemin, J-C

2015-10-01

We report on the tentative detection of trans ethyl methyl ether (tEME), t-CH 3 CH 2 OCH 3 , through the identification of a large number of rotational lines from each one of the spin states of the molecule towards Orion KL. We also search for gauche-trans-n-propanol, Gt-n-CH 3 CH 2 CH 2 OH, an isomer of tEME in the same source. We have identified lines of both species in the IRAM 30 m line survey and in the ALMA Science Verification data. We have obtained ALMA maps to establish the spatial distribution of these species. Whereas tEME mainly arises from the compact ridge component of Orion, Gt-n-propanol appears at the emission peak of ethanol (south hot core). The derived column densities of these species at the location of their emission peaks are ≤(4.0 ± 0.8) × 10 15 cm -2 and ≤(1.0 ± 0.2)× 10 15 cm -2 for tEME and Gt-n-propanol, respectively. The rotational temperature is ~100 K for both molecules. We also provide maps of CH 3 OCOH, CH 3 CH 2 OCOH, CH 3 OCH 3 , CH 3 OH, and CH 3 CH 2 OH to compare the distribution of these organic saturated O-bearing species containing methyl and ethyl groups in this region. Abundance ratios of related species and upper limits to the abundances of non-detected ethers are provided. We derive an abundance ratio N (CH 3 OCH 3 )/ N (tEME) ≥ 150 in the compact ridge of Orion.

Diazadienes in chemistry of lanthanides: latest view on old ligands. Synthesis, structure and properties of complexes {[(R)CNC6H3Pr2i]2}Lu(THF)2(μ-Cl)2Li(THF2 (R=CH3, CH2)

International Nuclear Information System (INIS)

Makhrova, T.V.; Fukin, G.K.; Cherkasov, A.V.; Trifonov, A.A.

2008-01-01

Reaction of dianion derivative [DADLi 2 ] (DAD -1,4-bis(2,6-diisopropylphenyl)-2,3-dimethyl-1,4-diaza-1,3-butadiene) prepared in situ by the reduction of corresponding DAD by the excess of metal lithium in THF with anhydrous LuCl 3 (1:1) results in the formation of the metal cyclic complex {[(R)CNC 6 H 3 Pr 2 i ] 2 }Lu(THF) 2 (μ-Cl) 2 Li(THF) 2 (1) containing the fragment N-C(Me)=C(Me)-N. DAD Treatment by two equivalents BuLi in the mixture ether-hexane (20 Deg C) results in the activation of the C-H bond of methyl substitutes at imine carbon. By the reaction of dilithium derivative [DAD - 2 H Li 2 ] formed in situ with LuCl 3 in THF the complex {[(CH 2 )CNC 6 H 3 Pr 2 i ] 2 }Lu(THF) 2 (μ-Cl) 2 Li(THF) 2 (2) with diamide ligand N-C(=CH 2 )-C(=CH 2 )-N was prepared. Structures of 1 and 2 complexes have been established by X-ray structure analysis [ru

Pathways of CH3Hg and Hg ingestion in benthic organisms: an enriched isotope approach.

Science.gov (United States)

Taylor, Vivien F; Bugge, Deenie; Jackson, Brian P; Chen, Celia Y

2014-05-06

Mercury is a widespread contaminant in marine food webs, and identifying uptake pathways of mercury species, CH3Hg(+) and Hg(2+), into low trophic level organisms is important to understanding its entry into marine food webs. Enriched stable isotope tracers were used to study benthic vs. pelagic pathways of CH3Hg(+) and Hg(2+) uptake via food to the infaunal estuarine amphipod, Leptocheirus plumulosus. Algal cells differentially labeled with isotopically enriched CH3Hg(+) or Hg(2+) were added simultaneously to the sediment and water column of microcosms, and Hg species were monitored in amphipods and in sediment and water compartments. Methylation of Hg(2+) occurred during the course of the experiment, enhancing the uptake of Hg(2+) spikes. Trophic transfer of Hg from algae added to the water column was determined to be the major uptake route for amphipods, suggesting inputs of contaminated organic matter from the pelagic zone are important to mercury bioaccumulation even in organisms living in sediments.

EPR investigation of gamma-irradiated L-citrulline, α-methyl-DL-serine, 3-fluoro-DL-valine and N-acetyl-L-cysteine

Science.gov (United States)

Osmanoğlu, Y. Emre; Sütçü, Kerem; Başkan, M. Halim

2017-02-01

The spectroscopic parameters of the paramagnetic species produced in gamma-irradiated L-citrulline, α-methyl-DL-serine, 3-fluoro-DL-valine and N-acetyl-L-cysteine were investigated at room temperature at a dose of 20 kGy by using EPR technique. The paramagnetic species were attributed to NH2CONH(CH2)3ĊNH2COOH, HOCH2ĊCH3COOH and HOĊHCCH3NH2COOH, CH3CH3ĊCHNH2COOH and SHCH2ĊNHCOCH3COOH radicals, respectively. EPR data of the unpaired electron with the environmental protons and 14N nucleus were used to characterize the contributing radicals produced in gamma irradiated compounds. In this paper, the stability of these compounds at room temperature after irradiation was also studied.

Atomic force measurements of 16-mercaptohexadecanoic acid and its salt with CH3, OH, and CONHCH3 functionalized self-assembled monolayers

International Nuclear Information System (INIS)

Morales-Cruz, Angel L.; Tremont, Rolando; Martinez, Ramon; Roman-tilde ach, Rodolfo; Cabrera, Carlos R.

2005-01-01

Chemical and mechanical properties of different compounds can be elucidated by measuring fundamental forces such as adhesion, attraction and repulsion, between modified surfaces by means of atomic force microscopy (AFM) in force mode calibration. This work presents a combination of AFM, self-assembled monolayers (SAMs), and crystallization techniques to study the forces of interaction between excipients and active ingredients used in pharmaceutical formulations. SAMs of 16-mercaptohexadecanoate, which represent magnesium stereate, were used to modify the probe tip, whereas CH 3 -, OH- and CONHCH 3 -functional SAMs were formed on a gold-coated mica substrate, and used as examples of the surfaces of lactose and theophylline. The crystals of lactose and theophylline were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The modification of gold surfaces with 16-mercaptohexadecanoate, 10-mercapto-1-decanol (OH-functional SAM), 1-decanethiol (CH 3 -functional) and N-methyl-11-mercaptoundecanamide (CONHCH 3 -functional SAM) was studied by X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and Fourier transform-infrared spectroscopy (FT-IR) in specular reflectance mode. XPS and AES results of the modified surfaces showed the presence of sulfur binding, and kinetic energies that correspond to the presence of 10-mercapto-1-decanol, 1-decanethiol, N-methyl-11-mercaptoundecanamide and the salt of 16-mercaptohexadecanoic acid. The absorption bands in the IR spectra further confirm the modification of the gold-coated substrates with these compounds. Force versus distance measurements were performed between the modified tip and the modified gold-coated mica substrates. The mean adhesion forces between the COO - Ca 2+ functionalized tip and the CH 3 -, OH-, and CONHCH 3 -modified substrates were determined to be 4.5, 8.9 and 6.3 nN, respectively. The magnitude of the adhesion force (ion-dipole) interaction between the modified

Novel high-throughput screening system for identifying STAT3-SH2 antagonists

International Nuclear Information System (INIS)

Uehara, Yutaka; Mochizuki, Masato; Matsuno, Kenji; Haino, Takeharu; Asai, Akira

2009-01-01

Constitutive activation of the oncogenic transcription factor STAT3 frequently occurs in various human malignancies. STAT3 activation involves dimerization via intermolecular pTyr-SH2 interaction. Thus, antagonizing this interaction is a feasible approach to inhibit STAT3 activation for cancer therapy. In order to identify selective STAT3 inhibitors, we developed a biochemical HTS system based on AlphaScreen technology, which measures the abilities of test compounds to antagonize pTyr-SH2 interactions. We screened our chemical libraries using this system and identified 5,15-diphenylporphyrin (5,15-DPP) as a selective STAT3-SH2 antagonist. Selective inhibition of STAT3 nuclear translocation and DNA biding activity was observed in cells treated with 5,15-DPP. IL-6-dependent dimerization of STAT3, c-myc promoter binding and c-myc protein expression were all suppressed by 5,15-DPP, whereas no decrement in either expression or phosphorylation level of STAT3 was observed. Thus, the HTS assay system represented herein may be useful for identifying novel STAT3-SH2 antagonists.

SH3 Domains Differentially Stimulate Distinct Dynamin I Assembly Modes and G Domain Activity.

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Sai Krishnan

Full Text Available Dynamin I is a highly regulated GTPase enzyme enriched in nerve terminals which mediates vesicle fission during synaptic vesicle endocytosis. One regulatory mechanism involves its interactions with proteins containing Src homology 3 (SH3 domains. At least 30 SH3 domain-containing proteins bind dynamin at its proline-rich domain (PRD. Those that stimulate dynamin activity act by promoting its oligomerisation. We undertook a systematic parallel screening of 13 glutathione-S-transferase (GST-tagged endocytosis-related SH3 domains on dynamin binding, GTPase activity and oligomerisation. No correlation was found between dynamin binding and their potency to stimulate GTPase activity. There was limited correlation between the extent of their ability to stimulate dynamin activity and the level of oligomerisation, indicating an as yet uncharacterised allosteric coupling of the PRD and G domain. We examined the two variants, dynamin Iab and Ibb, which differ in the alternately splice middle domain α2 helix. They responded differently to the panel of SH3s, with the extent of stimulation between the splice variants varying greatly between the SH3s. This study reveals that SH3 binding can act as a heterotropic allosteric regulator of the G domain via the middle domain α2 helix, suggesting an involvement of this helix in communicating the PRD-mediated allostery. This indicates that SH3 binding both stabilises multiple conformations of the tetrameric building block of dynamin, and promotes assembly of dynamin-SH3 complexes with distinct rates of GTP hydrolysis.

Electron paramagnetic resonance of gamma irradiated (CH3)3NHClO4 and CH3NH3ClO4 single crystals

International Nuclear Information System (INIS)

Yavuz, Metin; Koeksal, Fevzi

1999-01-01

Gamma irradiation damage centers in (CH 3 ) 3 NHClO 4 and CH 3 NH 3 ClO 4 single crystals have been investigated at room temperature by the electron paramagnetic resonance (EPR) technique. It has been found that γ-irradiation produces the (CH 3 ) 3 N + radical in the first, and NH + 3 and ClO 3 radicals in the second compound. The EPR parameters of the observed radicals have been determined and discussed

Protection of aliphatic alcohols by thiols

International Nuclear Information System (INIS)

Nanobashivili, E.M.; Chirakadze, G.G.; Panchvidze, M.V.; Gvilava, S.E.; Khidesheli, G.I.

1973-01-01

Study was made of methyl, ethyl, propyl, butyl and penthyl alcohols. The aqueous solutions of the alcohols were X-irradiated. Results are presented of the action of high-energy particles on the solutions of ethyl, propyl and butyl alcohols in the presence and absence of the minor amounts of ethanthiol. Protective effect of the -SH group was established. Addition of 1.10 -6 mol/1 of ethanthiol to butyl alcohol protects it completely against radiation conversions up to a dose of 8.10 19 eV/ml. Consideration is given to the effect of thioalcohol additives on the formation of some products of alcohol radiation oxidation. Introduction of mercaptans to the system or that of the -SH group to the organic compound molecule enhances its radiation resistance [ru

Mechanistic features of isomerizing alkoxycarbonylation of methyl oleate

KAUST Repository

Roesle, Philipp

2012-10-24

The weakly coordinated triflate complex [(P̂P)Pd(OTf)] +(OTf)- (1) (P̂P = 1,3-bis(di-tert- butylphosphino)propane) is a suitable reactive precursor for mechanistic studies of the isomerizing alkoxcarbonylation of methyl oleate. Addition of CH 3OH or CD3OD to 1 forms the hydride species [(P ̂P)PdH(CH3OH)]+(OTf)- (2-CH3OH) or the deuteride [(P̂P)PdD(CD 3OD)]+(OTf)- (2D-CD3OD), respectively. Further reaction with pyridine cleanly affords the stable and isolable hydride [(P̂P)PdH(pyridine)]+(OTf) - (2-pyr). This complex yields the hydride fragment free of methanol by abstraction of pyridine with BF3OEt2, and thus provides an entry to mechanistic observations including intermediates reactive toward methanol. Exposure of methyl oleate (100 equiv) to 2D-CD 3OD resulted in rapid isomerization to the thermodynamic isomer distribution, 94.3% of internal olefins, 5.5% of α,β-unsaturated ester and <0.2% of terminal olefin. Reaction of 2-pyr/BF3OEt 2 with a stoichiometric amount of 1-13C-labeled 1-octene at -80 °C yields a 50:50 mixture of the linear alkyls [(P ̂P)Pd13CH2(CH2) 6CH3]+ and [(P̂P)PdCH 2(CH2)6 13CH3] + (4a and 4b). Further reaction with 13CO yields the linear acyls [(P̂P)Pd13C(=O)12/13CH 2(CH2)6 12/13CH3(L)] + (5-L; L = solvent or 13CO). Reaction of 2-pyr/BF 3·OEt2 with a stoichiometric amount of methyl oleate at -80 °C also resulted in fast isomerization to form a linear alkyl species [(P̂P)PdCH2(CH2) 16C(=O)OCH3]+ (6) and a branched alkyl stabilized by coordination of the ester carbonyl group as a four membered chelate [(P̂P)PdCH{(CH2)15CH 3}C(=O)OCH3]+ (7). Addition of carbon monoxide (2.5 equiv) at -80 °C resulted in insertion to form the linear acyl carbonyl [(P̂P)PdC(=O)(CH2)17C(=O)OCH 3(CO)]+ (8-CO) and the five-membered chelate [(P ̂P)PdC(=O)CH{(CH2)15CH3}C(=O) OCH3]+ (9). Exposure of 8-CO and 9 to 13CO at -50 °C results in gradual incorporation of the 13C label. Reversibility of 7 + CO ⇄ 9 is also evidenced by ΔG = -2.9 kcal mol-1 and

A unique set of SH3-SH3 interactions controls IB1 homodimerization

DEFF Research Database (Denmark)

Kristensen, Ole; Guenat, Sylvie; Dar, Imran

2006-01-01

Islet-brain 1 (IB1 or JIP-1) is a scaffold protein that interacts with components of the c-Jun N-terminal kinase (JNK) signal-transduction pathway. IB1 is expressed at high levels in neurons and in pancreatic beta-cells, where it controls expression of several insulin-secretory components...... reduces IB1-dependent basal JNK activity in 293T cells. Impaired dimerization also results in a reduction in glucose transporter type 2 expression and in glucose-dependent insulin secretion in pancreatic beta-cells. Taken together, these results indicate that IB1 homodimerization through its SH3 domain...

Structure determination of human Lck unique and SH3 domains by nuclear magnetic resonance spectroscopy

Directory of Open Access Journals (Sweden)

Willbold Dieter

2003-05-01

Full Text Available Abstract Background Protein tyrosine kinases are involved in signal transduction pathways that regulate cell growth, differentiation, activation and transformation. Human lymphocyte specific kinase (Lck is a 56 kDa protein involved in T-cell- and IL2-receptor signaling. Three-dimensional structures are known for SH3, SH2 and kinase domains of Lck as well as for other tyrosine kinases. No structure is known for the unique domain of any Src-type tyrosine kinase. Results Lck(1–120 comprising unique and SH3 domains was structurally investigated by nuclear magnetic resonance spectroscopy. We found the unique domain, in contrast to the SH3 part, to have basically no defined structural elements. The solution structure of the SH3 part could be determined with very high precision. It does not show significant differences to Lck SH3 in the absence of the unique domain. Minor differences were observed to the X-ray structure of Lck SH3. Conclusion The unique domain of Lck does not contain any defined structure elements in the absence of ligands and membranes. Presence of the unique domain is not relevant to the three-dimensional structure of the Lck SH3 domain.

Photostriction of CH3NH3PbBr3 Perovskite Crystals

KAUST Repository

Wei, Tzu-Chiao

2017-07-17

Organic-inorganic hybrid perovskite materials exhibit a variety of physical properties. Pronounced coupling between phonon, organic cations, and the inorganic framework suggest that these materials exhibit strong light-matter interactions. The photoinduced strain of CH3 NH3 PbBr3 is investigated using high-resolution and contactless in situ Raman spectroscopy. Under illumination, the material exhibits large blue shifts in its Raman spectra that indicate significant structural deformations (i.e., photostriction). From these shifts, the photostrictive coefficient of CH3 NH3 PbBr3 is calculated as 2.08 × 10-8 m2 W-1 at room temperature under visible light illumination. The significant photostriction of CH3 NH3 PbBr3 is attributed to a combination of the photovoltaic effect and translational symmetry loss of the molecular configuration via strong translation-rotation coupling. Unlike CH3 NH3 PbI3 , it is noted that the photostriction of CH3 NH3 PbBr3 is extremely stable, demonstrating no signs of optical decay for at least 30 d. These results suggest the potential of CH3 NH3 PbBr3 for applications in next-generation optical micro-electromechanical devices.

Sulphur chemistry in the L1544 pre-stellar core

Science.gov (United States)

Vastel, Charlotte; Quénard, D.; Le Gal, R.; Wakelam, V.; Andrianasolo, A.; Caselli, P.; Vidal, T.; Ceccarelli, C.; Lefloch, B.; Bachiller, R.

2018-05-01

The L1544 pre-stellar core has been observed as part of the ASAI IRAM 30m Large Program as well as follow-up programs. These observations have revealed the chemical richness of the earliest phases of low-mass star-forming regions. In this paper we focus on the twenty-one sulphur bearing species (ions, isotopomers and deuteration) that have been detected in this spectral-survey through fifty one transitions: CS, CCS, C3S, SO, SO2, H2CS, OCS, HSCN, NS, HCS+, NS+ and H2S. We also report the tentative detection (4 σ level) for methyl mercaptan (CH3SH). LTE and non-LTE radiative transfer modelling have been performed and we used the NAUTILUS chemical code updated with the most recent chemical network for sulphur to explain our observations. From the chemical modelling we expect a strong radial variation for the abundances of these species, which mostly are emitted in the external layer where non thermal desorption of other species has previously been observed. We show that the chemical study cannot be compared to what has been done for the TMC-1 dark cloud, where the abundance is supposed constant along the line of sight, and conclude that a strong sulphur depletion is necessary to fully reproduce our observations of the prototypical pre-stellar core L1544.

Drosophila photoreceptor axon guidance and targeting requires the dreadlocks SH2/SH3 adapter protein.

Science.gov (United States)

Garrity, P A; Rao, Y; Salecker, I; McGlade, J; Pawson, T; Zipursky, S L

1996-05-31

Mutations in the Drosophila gene dreadlocks (dock) disrupt photoreceptor cell (R cell) axon guidance and targeting. Genetic mosaic analysis and cell-type-specific expression of dock transgenes demonstrate dock is required in R cells for proper innervation. Dock protein contains one SH2 and three SH3 domains, implicating it in tyrosine kinase signaling, and is highly related to the human proto-oncogene Nck. Dock expression is detected in R cell growth cones in the target region. We propose Dock transmits signals in the growth cone in response to guidance and targeting cues. These findings provide an important step for dissection of signaling pathways regulating growth cone motility.

Investigation on thermal evaporated CH3NH3PbI3 thin films

Directory of Open Access Journals (Sweden)

Youzhen Li

2015-09-01

Full Text Available CH3NH3I, PbI2 and CH3NH3PbI3 films were fabricated by evaporation and characterized with X-ray Photoelectron Spectroscopy (XPS and X-ray diffraction (XRD. The XPS results indicate that the PbI2 and CH3NH3PbI3 films are more uniform and stable than the CH3NH3I film. The atomic ratio of the CH3NH3I, PbI2 and CH3NH3PbI3 films are C:N:I=1.00:1.01:0.70, Pb:I= 1.00:1.91 and C: N: Pb: I = 1.29:1.07:1.00:2.94, respectively. The atomic ratio of CH3NH3PbI3 is very close to that of the ideal perovskite. Small angle x-ray diffraction results demonstrate that the as evaporated CH3NH3PbI3 film is crystalline. The valence band maximum (VBM and work function (WF of the CH3NH3PbI3 film are about 0.85eV and 4.86eV, respectively.

Synthesis of methyl [(chloro-2 ethyl)-3 nitroso-3 Ureido]-3 Didesoxy-2,3 α-D-Arabino-hexopyrannoside labelled with carbon-14 or carbon-13 (CY 233 - SR 90008)

International Nuclear Information System (INIS)

Sion, R.; Schumer, A.; Durme, E. van; Gouyette, A.; Geslin, M.; Fournier, J.P.; Roger, P.

1990-01-01

CY 233 (Ecomustine or SR 90098) is a new antitumour nitrosourea: it is characterized by a 2-chloroethylnitrosourea substituent on a dideoxycarbohydrate. It has been labelled with 14 C on a) the carbonyl group of the urea in four stages starting with 14 COCl 2 , b) the second carbon of the chloroethyl group in four stages starting with [ 14 C] ethanolamine, and c) on the methyl group on the anomeric centre of the carbohydrate in three stages starting with 14 CH 3 OH. The final position was also labelled with 13 C starting with 13 CH 3 OH. These differently labelled compounds are suitable for mechanistic studies of antitumour activity. (author)

Transient infrared absorption of t-CH3C(O)OO, c-CH3C(O)OO, and α-lactone recorded in gaseous reactions of CH3CO and O2

Science.gov (United States)

Chen, Sun-Yang; Lee, Yuan-Pern

2010-03-01

A step-scan Fourier-transform infrared spectrometer coupled with a multipass absorption cell was utilized to monitor the transient species produced in gaseous reactions of CH3CO and O2; IR absorption spectra of CH3C(O)OO and α-lactone were observed. Absorption bands with origins at 1851±1, 1372±2, 1169±6, and 1102±3 cm-1 are attributed to t-CH3C(O)OO, and those at 1862±3, 1142±4, and 1078±6 cm-1 are assigned to c-CH3C(O)OO. A weak band near 1960 cm-1 is assigned to α-lactone, cyc-CH2C(O)O, a coproduct of OH. These observed rotational contours agree satisfactorily with simulated bands based on predicted rotational parameters and dipole derivatives, and observed vibrational wavenumbers agree with harmonic vibrational wavenumbers predicted with B3LYP/aug-cc-pVDZ density-functional theory. The observed relative intensities indicate that t-CH3C(O)OO is more stable than c-CH3C(O)OO by 3±2 kJ mol-1. Based on these observations, the branching ratio for the OH+α-lactone channel of the CH3CO+O2 reaction is estimated to be 0.04±0.01 under 100 Torr of O2 at 298 K. A simple kinetic model is employed to account for the decay of CH3C(O)OO.

Transient infrared absorption of t-CH3C(O)OO, c-CH3C(O)OO, and alpha-lactone recorded in gaseous reactions of CH3CO and O2.

Science.gov (United States)

Chen, Sun-Yang; Lee, Yuan-Pern

2010-03-21

A step-scan Fourier-transform infrared spectrometer coupled with a multipass absorption cell was utilized to monitor the transient species produced in gaseous reactions of CH(3)CO and O(2); IR absorption spectra of CH(3)C(O)OO and alpha-lactone were observed. Absorption bands with origins at 1851+/-1, 1372+/-2, 1169+/-6, and 1102+/-3 cm(-1) are attributed to t-CH(3)C(O)OO, and those at 1862+/-3, 1142+/-4, and 1078+/-6 cm(-1) are assigned to c-CH(3)C(O)OO. A weak band near 1960 cm(-1) is assigned to alpha-lactone, cyc-CH(2)C(=O)O, a coproduct of OH. These observed rotational contours agree satisfactorily with simulated bands based on predicted rotational parameters and dipole derivatives, and observed vibrational wavenumbers agree with harmonic vibrational wavenumbers predicted with B3LYP/aug-cc-pVDZ density-functional theory. The observed relative intensities indicate that t-CH(3)C(O)OO is more stable than c-CH(3)C(O)OO by 3+/-2 kJ mol(-1). Based on these observations, the branching ratio for the OH+alpha-lactone channel of the CH(3)CO+O(2) reaction is estimated to be 0.04+/-0.01 under 100 Torr of O(2) at 298 K. A simple kinetic model is employed to account for the decay of CH(3)C(O)OO.

Synthesis of methyl ((chloro-2 ethyl)-3 nitroso-3 Ureido)-3 Didesoxy-2,3. alpha. -D-Arabino-hexopyrannoside labelled with carbon-14 or carbon-13 (CY 233 - SR 90008). Synthese du methyl ((chloro-2 ethyl)-3 nitroso-3 Ureido)-3 Didesoxy-2,3. alpha. -D-Arabino-hexopyrannoside marque au carbone-14 ou carbone-13 (CY 233 - SR 90008)

Energy Technology Data Exchange (ETDEWEB)

Sion, R.; Schumer, A.; Durme, E. van (Sanofi Recherche, Brussels (Belgium)); Gouyette, A. (Centre de Lutte Contre le Cancer Gustave-Roussy, 94 - Villejuif (France)); Geslin, M.; Fournier, J.P.; Roger, P. (Sanofi Recherche, Montrouge (France). Inst. Choay); Berger, Y. (Sanofi Recherche, Montpellier (France))

1990-06-01

CY 233 (Ecomustine or SR 90098) is a new antitumour nitrosourea: it is characterized by a 2-chloroethylnitrosourea substituent on a dideoxycarbohydrate. It has been labelled with {sup 14}C on (a) the carbonyl group of the urea in four stages starting with {sup 14}COCl{sub 2}, (b) the second carbon of the chloroethyl group in four stages starting with ({sup 14}C) ethanolamine, and (c) on the methyl group on the anomeric centre of the carbohydrate in three stages starting with {sup 14}CH{sub 3}OH. The final position was also labelled with {sup 13}C starting with {sup 13}CH{sub 3}OH. These differently labelled compounds are suitable for mechanistic studies of antitumour activity. (author).

New superhindered polydentate polyphosphine ligands P(CH2CH2P(t)Bu2)3, PhP(CH2CH2P(t)Bu2)2, P(CH2CH2CH2P(t)Bu2)3, and their ruthenium(II) chloride complexes.

Science.gov (United States)

Gilbert-Wilson, Ryan; Field, Leslie D; Bhadbhade, Mohan M

2012-03-05

The synthesis and characterization of the extremely hindered phosphine ligands, P(CH(2)CH(2)P(t)Bu(2))(3) (P(2)P(3)(tBu), 1), PhP(CH(2)CH(2)P(t)Bu(2))(2) (PhP(2)P(2)(tBu), 2), and P(CH(2)CH(2)CH(2)P(t)Bu(2))(3) (P(3)P(3)(tBu), 3) are reported, along with the synthesis and characterization of ruthenium chloro complexes RuCl(2)(P(2)P(3)(tBu)) (4), RuCl(2)(PhP(2)P(2)(tBu)) (5), and RuCl(2)(P(3)P(3)(tBu)) (6). The bulky P(2)P(3)(tBu) (1) and P(3)P(3)(tBu) (3) ligands are the most sterically encumbered PP(3)-type ligands so far synthesized, and in all cases, only three phosphorus donors are able to bind to the metal center. Complexes RuCl(2)(PhP(2)P(2)(tBu)) (5) and RuCl(2)(P(3)P(3)(tBu)) (6) were characterized by crystallography. Low temperature solution and solid state (31)P{(1)H} NMR were used to demonstrate that the structure of RuCl(2)(P(2)P(3)(tBu)) (4) is probably analogous to that of RuCl(2)(PhP(2)P(2)(tBu)) (5) which had been structurally characterized.

Appropriate sample bags and syringes for preserving breath samples in breath odor research : a technical note

NARCIS (Netherlands)

Winkel, E. G.; Tangerman, A.

It is now generally accepted that the volatile sulfur compounds (VSCs) hydrogen sulfide, methyl mercaptan and dimethyl sulfide are the main contributors to halitosis when of oropharyngeal origin. The VSCs hydrogen sulfide and methyl mercaptan are the major causes of bad breath in oral malodour

Production of gaseous radiotracers CH3I and I2 through Na123I salt

International Nuclear Information System (INIS)

Candeiro, R.E.M.; Pereira, W.P.

2011-01-01

The objective of the present work was to develop, separately, methodology for production of two gaseous tracers through the sodium iodide NaI marked with 123 I. Found in the nature in form different, the iodine has been used in diverse works in the area of the industry and health. These two forms of the gaseous iodine, the methyl iodide, CH 3 I, and molecular iodine, I 2 , are very unstable and volatile in the ambient temperature and presents different problems in clean-up and monitoring systems. The syntheses were processed with sodium iodide (NaI) 1M aqueous solution marked with 1 23I . The production of gas I 2 was realized with in chlorine acid (HCl) and sodium iodate salt (NaIO 3 ) and the CH 3 I was used, the salt of NaI and the reagent (CH 3 ) 2 SO 4 . The production of gases was initially realized through in unit in glass with an inert material and the purpose was to study the kinetic of reaction and to determine the efficiency of production. The two synthesis occurs in the reaction bottle and after of produced, the gas is stored in the collect bottle that contains a starch solution for fixed the I 2 , and in syntheses of CH 3 I contains a silver nitrate solution for your fixation. To determine the efficiency of production of gases, analytic tests were realized, where the consumption of iodide ions of the bottle of reaction are measured. The optimization of production of the each gaseous tracer was studied varying parameter as: concentration of iodide, concentration of acid and temperature. After, the syntheses of the radiotracers were realized in the compact unit, having been used as main reagent the salt radiated of sodium iodide, Na 123 I. The transportation of elementary iodine and methyl iodine was studied by a scintillation detector NaI (2 x 2)' positioned in the reaction bottle. (author)

Detection and characterization of partially unfolded oligomers of the SH3 domain of α-Spectrin

NARCIS (Netherlands)

Casares, S.; Sadqi, M.; López-Mayorga, O.; Conejero-Lara, F.; van Nuland, N.A.J.

2004-01-01

For the purpose of equilibrium and kinetic folding-unfolding studies, the SH3 domain of α-spectrin (spc-SH3) has long been considered a classic two-state folding protein. In this work we have indeed observed that the thermal unfolding curves of spc-SH3 measured at pH 3.0 by differential scanning

Degradation of ethyl mercaptan and its major intermediate diethyl disulfide by Pseudomonas sp. strain WL2.

Science.gov (United States)

Wang, Xiangqian; Wu, Chao; Liu, Nan; Li, Sujing; Li, Wei; Chen, Jianmeng; Chen, Dongzhi

2015-04-01

A Pseudomonas sp. strain WL2 that is able to efficiently metabolize ethyl mercaptan (EM) into diethyl disulfide (DEDS) through enzymatic oxidation was isolated from the activated sludge of a pharmaceutical wastewater plant. One hundred percent removal of 113.5 mg L(-1) EM and 110.3 mg L(-1) DEDS were obtained within 14 and 32 h, respectively. A putative EM degradation pathway that involved the catabolism via DEDS was proposed, which indicated DEDS were further mineralized into carbon dioxide (CO2), bacterial cells, and sulfate (SO4 (2-)) through the transformation of element sulfur and ethyl aldehyde. Degradation kinetics for EM and DEDS with different initial concentrations by strain WL2 were evaluated using Haldane-Andrews model with maximum specific degradation rates of 3.13 and 1.33 g g(-1) h(-1), respectively, and maximum degradation rate constants of 0.522 and 0.175 h(-1) using pseudo-first-order kinetic model were obtained. Results obtained that aerobic degradation of EM by strain WL2 was more efficient than those from previous studies. Substrate range studies of strain WL2 demonstrated its ability to degrade several mercaptans, disulfides, aldehydes, and methanol. All the results obtained highlight the potential of strain WL2 for the use in the biodegradation of volatile organic sulfur compounds (VOSCs).

H-alpha observations of Sh2-190, Sh2-222, Sh2-229, Sh2-236 HII regions

Science.gov (United States)

Sahan, Muhittin

2018-02-01

Hα spectral line (6563Å) profiles of four northern HII regions in the our galaxy (Sh2-190, Sh2-222, Sh2-229, Sh2-236) have been obtained using DEFPOS spectrometer, located at coude focus of 150 cm RTT150 telescope at TUBITAK National Observatory (TUG, Antalya, Turkey). Observations were carried out at nights of 2015 December 24-27 with long exposure times ranging from 900s to 3600s. The LSR velocities and the linewidths (Full Width Half Maximum: FWHM) of the Hα emission lines were found to be in the range of -45.46 kms-1 to +3.57 kms-1 and 38.50 kms-1 to 44.10 kms-1, respectively. The Sh2-229 HII region is the faintest one (211.16 R), while the Sh2-236 HII region (IC410) is brightest source (535.75 R). The LSR velocity and the line width (FWHM) results of the DEFPOS/RTT150 system were compared with the data by several authors given in literature and results of DEFPOS data were found to be in good agreement with data given in literature.

Analyzing velocity map images to distinguish the primary methyl photofragments from those produced upon C-Cl bond photofission in chloroacetone at 193 nm

Science.gov (United States)

Alligood, Bridget W.; Straus, Daniel B.; Butler, Laurie J.

2011-07-01

We use a combination of crossed laser-molecular beam scattering experiments and velocity map imaging experiments to investigate the three primary photodissociation channels of chloroacetone at 193 nm: C-Cl bond photofission yielding CH3C(O)CH2 radicals, C-C bond photofission yielding CH3CO and CH2Cl products, and C-CH3 bond photofission resulting in CH3 and C(O)CH2Cl products. Improved analysis of data previously reported by our group quantitatively identifies the contribution of this latter photodissociation channel. We introduce a forward convolution procedure to identify the portion of the signal, derived from the methyl image, which results from a two-step process in which C-Cl bond photofission is followed by the dissociation of the vibrationally excited CH3C(O)CH2 radicals to CH3 + COCH2. Subtracting this from the total methyl signal identifies the methyl photofragments that result from the CH3 + C(O)CH2Cl photofission channel. We find that about 89% of the chloroacetone molecules undergo C-Cl bond photofission to yield CH3C(O)CH2 and Cl products; approximately 8% result in C-C bond photofission to yield CH3CO and CH2Cl products, and the remaining 2.6% undergo C-CH3 bond photofission to yield CH3 and C(O)CH2Cl products.

Dissociative electron attachment to methyl chloride: A quasi-diatomic potential curve for the fragmentation of the metastable CH3Cl- anion

International Nuclear Information System (INIS)

Mach, P.; Urban, J.; Staemmler, V.

2009-01-01

Potential energy curves have been calculated for the dissociation of the neutral CH 3 Cl molecule and its negative ion into CH 3 + Cl and CH 3 +Cl - , respectively. The neutral molecule and the anion could be treated by means of standard wave function based quantum chemical ab initio methods for C-Cl distances larger than about 2.4 A, where CH 3 Cl - is a stable anion. In the present calculation MP3 and CCSD(T) were employed. At shorter C-Cl distances the CH 3 Cl - anion is only metastable and cannot be treated by such methods. We have applied a stabilization scheme, first proposed by Nestmann and Peyerimhoff, to stabilize the metastable anion by adding extra positive charges to the molecule. By this trick it was possible to generate the resonance energy E res and width Γ as functions of the C-Cl distance in the resonance regime between 1.5 and 2.5 A. The calculated values for the threshold energy E thresh and the exothermicity ΔE 0 of the DEA (dissociative electron attachment) process are in very good agreement with experiment; the vertical attachment energy (VAE) is smaller than its experimental counterpart

Physical and functional interactions between SH2 and SH3 domains of the Src family protein tyrosine kinase p59fyn

NARCIS (Netherlands)

Panchamoorthy, G.; Fukazawa, T.; Stolz, L.; Payne, G.; Reedquist, K.; Shoelson, S.; Songyang, Z.; Cantley, L.; Walsh, C.; Band, H.

1994-01-01

The Src family protein tyrosine kinases participate in signalling through cell surface receptors that lack intrinsic tyrosine kinase domains. All nine members of this family possess adjacent Src homology (SH2 and SH3) domains, both of which are essential for repression of the enzymatic activity. The

The ShcA SH2 domain engages a 14-3-3/PI3'K signaling complex and promotes breast cancer cell survival.

Science.gov (United States)

Ursini-Siegel, J; Hardy, W R; Zheng, Y; Ling, C; Zuo, D; Zhang, C; Podmore, L; Pawson, T; Muller, W J

2012-11-29

The ShcA adapter protein transmits activating signals downstream of receptor and cytoplasmic tyrosine kinases through the establishment of phosphotyrosine-dependent complexes. In this regard, ShcA possesses both a phosphotyrosine-binding domain (PTB) and Src homology 2 domain (SH2), which bind phosphotyrosine residues in a sequence-specific manner. Although the majority of receptor tyrosine kinases expressed in breast cancer cells bind the PTB domain, very little is known regarding the biological importance of SH2-driven ShcA signaling during mammary tumorigenesis. To address this, we employed transgenic mice expressing a mutant ShcA allele harboring a non-functional SH2 domain (ShcR397K) under the transcriptional control of the endogenous ShcA promoter. Using transplantation approaches, we demonstrate that SH2-dependent ShcA signaling within the mammary epithelial compartment is essential for breast tumor outgrowth, survival and the development of lung metastases. We further show that the ShcA SH2 domain activates the AKT pathway, potentially through a novel SH2-mediated complex between ShcA, 14-3-3ζ and the p85 regulatory subunit of phosphatidylinositol 3 (PI3') kinase. This study is the first to demonstrate that the SH2 domain of ShcA is critical for tumor survival during mammary tumorigenesis.

Searching for trans ethyl methyl ether in Orion KL★,★★

Science.gov (United States)

Tercero, B.; Cernicharo, J.; López, A.; Brouillet, N.; Kolesniková, L.; Motiyenko, R. A.; Margulès, L.; Alonso, J. L.; Guillemin, J.-C.

2015-01-01

We report on the tentative detection of trans ethyl methyl ether (tEME), t-CH3CH2OCH3, through the identification of a large number of rotational lines from each one of the spin states of the molecule towards Orion KL. We also search for gauche-trans-n-propanol, Gt-n-CH3CH2CH2OH, an isomer of tEME in the same source. We have identified lines of both species in the IRAM 30 m line survey and in the ALMA Science Verification data. We have obtained ALMA maps to establish the spatial distribution of these species. Whereas tEME mainly arises from the compact ridge component of Orion, Gt-n-propanol appears at the emission peak of ethanol (south hot core). The derived column densities of these species at the location of their emission peaks are ≤(4.0 ± 0.8) × 1015 cm−2 and ≤(1.0 ± 0.2)× 1015 cm−2 for tEME and Gt-n-propanol, respectively. The rotational temperature is ~100 K for both molecules. We also provide maps of CH3OCOH, CH3CH2OCOH, CH3OCH3, CH3OH, and CH3CH2OH to compare the distribution of these organic saturated O-bearing species containing methyl and ethyl groups in this region. Abundance ratios of related species and upper limits to the abundances of non-detected ethers are provided. We derive an abundance ratio N(CH3OCH3)/N(tEME) ≥ 150 in the compact ridge of Orion. PMID:26869726

Activation of PI3K/Akt signaling by n-terminal SH2 domain mutants of the p85α regulatory subunit of PI3K is enhanced by deletion of its c-terminal SH2 domain.

Science.gov (United States)

Hofmann, Bianca T; Jücker, Manfred

2012-10-01

The phosphoinositide 3-kinase (PI3K) is frequently activated in human cancer cells due to gain of function mutations in the catalytic (p110) and the regulatory (p85) subunits. The regulatory subunit consists of an SH3 domain and two SH2 domains. An oncogenic form of p85α named p65 lacking the c-terminal SH2 domain (cSH2) has been cloned from an irradiation-induced murine thymic lymphoma and transgenic mice expressing p65 in T lymphocytes develop a lymphoproliferative disorder. We have recently detected a c-terminal truncated form of p85α named p76α in a human lymphoma cell line lacking most of the cSH2 domain due to a frame shift mutation. Here, we report that the deletion of the cSH2 domain enhances the activating effects of the n-terminal SH2 domain (nSH2) mutants K379E and R340E on the PI3K/Akt pathway and micro tumor formation in a focus assay. Further analysis revealed that this transforming effect is mediated by activation of the catalytic PI3K isoform p110α and downstream signaling through mTOR. Our data further support a mechanistic model in which mutations of the cSH2 domain of p85α can abrogate its negative regulatory function on PI3K activity via the nSH2 domain of p85α. Copyright © 2012 Elsevier Inc. All rights reserved.

Proton location in (CH3)3N-H+-(CH3OH)n: A theoretical and infrared spectroscopic study

International Nuclear Information System (INIS)

Bing, Dan; Hamashima, Toru; Tsai, Chen-Wei; Fujii, Asuka; Kuo, Jer-Lai

2013-01-01

Highlights: • Preferential location of the excess proton in the trimethylamine-methanol clusters. • Collaboration between DFT calculations and IR spectroscopy. • The excess proton prefers the protonation to the trimethylamine moiety. - Abstract: The dependence of the preferential protonated site in (CH 3 ) 3 N-H + -(CH 3 OH) n on the cluster size was investigated using theoretical calculations and infrared spectroscopy measurements. While simple estimation from the magnitude of proton affinity suggested that the excess proton prefers the methanol site in n ⩾ 4, density functional theory calculations of the stabilization energy indicated the clear preference as protonation of the trimethylamine site, even for n = 9. Infrared spectra of the clusters were observed for n = 3–7. Spectral simulations were also performed using the quantum harmonic superposition approximation. The observed (CH 3 ) 3 N-H + -(CH 3 OH) n spectra were well interpreted by simulations of the isomers with the protonated trimethylamine ion core. It was shown that both the proton affinity and the mutual solvation energy govern the preferential location of the excess proton in binary component clusters

SH3 domain-mediated recruitment of host cell amphiphysins by alphavirus nsP3 promotes viral RNA replication.

Directory of Open Access Journals (Sweden)

Maarit Neuvonen

2011-11-01

Full Text Available Among the four non-structural proteins of alphaviruses the function of nsP3 is the least well understood. NsP3 is a component of the viral replication complex, and composed of a conserved aminoterminal macro domain implicated in viral RNA synthesis, and a poorly conserved carboxyterminal region. Despite the lack of overall homology we noted a carboxyterminal proline-rich sequence motif shared by many alphaviral nsP3 proteins, and found it to serve as a preferred target site for the Src-homology 3 (SH3 domains of amphiphysin-1 and -2. Nsp3 proteins of Semliki Forest (SFV, Sindbis (SINV, and Chikungunya viruses all showed avid and SH3-dependent binding to amphiphysins. Upon alphavirus infection the intracellular distribution of amphiphysin was dramatically altered and colocalized with nsP3. Mutations in nsP3 disrupting the amphiphysin SH3 binding motif as well as RNAi-mediated silencing of amphiphysin-2 expression resulted in impaired viral RNA replication in HeLa cells infected with SINV or SFV. Infection of Balb/c mice with SFV carrying an SH3 binding-defective nsP3 was associated with significantly decreased mortality. These data establish SH3 domain-mediated binding of nsP3 with amphiphysin as an important host cell interaction promoting alphavirus replication.

Adsorption/oxidation of sulfur-containing gases on nitrogen-doped activated carbon

Directory of Open Access Journals (Sweden)

Liu Qiang

2016-01-01

Full Text Available Coconut shell-based activated carbon (CAC was used for the removal of methyl mercaptan (MM. CAC was modified by urea impregnation and calcined at 450°C and 950°C. The desulfurization activity was determined in a fixed bed reactor under room temperature. The results showed that the methyl mercaptan adsorption/oxidation capacity of modified carbon caicined at 950°C is more than 3 times the capacity of original samples. On the other hand, the modified carbon caicined at 950°C also has a high capacity for the simultaneous adsorption/oxidation of methyl mercaptan and hydrogen sulfide.The introduce of basic nitrogen groups siginificantly increases the desulfurization since it can facilitate the electron transfer process between sulfur and oxygen. The structure and chemical properties are characterized using Boehm titration, N2 adsorption-desorption method, thermal analysis and elemental analysis. The results showed that the major oxidation products were dimethyl disulfide and methanesulfonic acid which adsorbed in the activated carbon.

Braked rotation of CH3 group in L-alanine monocrystals: temperature transformation of EPR spectrum

International Nuclear Information System (INIS)

Lemanov, V.V.; Sochava, L.S.

2003-01-01

EPR spectra temperature transformation of the irradiated alanine crystals is used for studying rotation of CH 3 methyl group in L-alamine monocrystals. 60 Co (2 x 10 4 Gy dose) was applied as a γ-radiation source. The simple method of experimental data processing which is reduced to obtaining the resonance lines width dependence on the temperature is used for the quantitative analysis of the spectrum temperature transformation. Temperature dependence of the CH 3 group rotation frequency is identified on the basis of these data. Activation energy U = 0.18 eV and pre-exponential multiplier ω 0 = 10 13 s -1 are determined from the EPR spectra temperature transformation which are in good agreement with values obtained earlier from the measurements of the proton spin-lattice relaxation in alanine polycrystal samples [ru

[CH(3)(CH(2))(11)NH(3)]SnI(3): a hybrid semiconductor with MoO(3)-type tin(II) iodide layers.

Science.gov (United States)

Xu, Zhengtao; Mitzi, David B

2003-10-20

The organic-inorganic hybrid [CH(3)(CH(2))(11)NH(3)]SnI(3) presents a lamellar structure with a Sn-I framework isotypic to that of MoO(3). The SnI(3)(-) layer consists of edge and corner-sharing SnI(6) octahedra in which one of the six Sn-I bonds is distinctly elongated (e.g., 3.62 A), indicating lone-pair stereoactivity for the Sn(II) atom. The overall electronic character remains comparable with that of the well-studied SnI(4)(2)(-)-based perovskite semiconductors, such as [CH(3)(CH(2))(11)NH(3)](2)SnI(4), with a red-shifted and broadened exciton peak associated with the band gap, apparently due to the increased dimensionality of the Sn-I framework. The title compound offers, aside from the hybrid perovskites, a new type of solution-processable Sn-I network for potential applications in semiconductive devices.

Reaction CH3 + OH studied over the 294-714 K temperature and 1-100 bar pressure ranges.

Science.gov (United States)

Sangwan, Manuvesh; Chesnokov, Evgeni N; Krasnoperov, Lev N

2012-08-30

Reaction of methyl radicals with hydroxyl radicals, CH(3) + OH → products (1) was studied using pulsed laser photolysis coupled to transient UV-vis absorption spectroscopy over the 294-714 K temperature and 1-100 bar pressure ranges (bath gas He). Methyl radicals were produced by photolysis of acetone at 193.3 nm. Hydroxyl radicals were generated in reaction of electronically excited oxygen atoms O((1)D), produced in the photolysis of N(2)O at 193.3 nm, with H(2)O. Temporal profiles of CH(3) were recorded via absorption at 216.4 nm using xenon arc lamp and a spectrograph; OH radicals were monitored via transient absorption of light from a dc discharge H(2)O/Ar low pressure resonance lamp at ca. 308 nm. The absolute intensity of the photolysis light inside the reactor was determined by an accurate in situ actinometry based on the ozone formation in the presence of molecular oxygen. The results of this study indicate that the rate constant of reaction 1 is pressure independent within the studied pressure and temperature ranges and has slight negative temperature dependence, k(1) = (1.20 ± 0.20) × 10(-10)(T/300)(-0.49) cm(3) molecule(-1) s(-1).

Synthesis and evaluation of alpha-[[(2-haloethyl)amino]methyl]-2- nitro-1H-imidazole-1-ethanols as prodrugs of alpha-[(1-aziridinyl)methyl]-2- nitro-1H-imidazole-1-ethanol (RSU-1069) and its analogues which are radiosensitizers and bioreductively activated cytotoxins

International Nuclear Information System (INIS)

Jenkins, T.C.; Naylor, M.A.; O'Neill, P.; Threadgill, M.D.; Cole, S.; Stratford, I.J.; Adams, G.E.; Fielden, E.M.; Suto, M.J.; Stier, M.A.

1990-01-01

alpha-[(1-Aziridinyl)methyl]-2-nitro-1H-imidazole-1-ethanols, of general formula ImCH2CH(OH)CH2NCR1R2CR3R4, where Im = 2-nitroimidazole and R1, R2, R3, R4 = H, Me, are radiosensitizers and selective bioreductively activated cytotoxins toward hypoxic tumor cells in vitro and in vivo. Treatment of the aziridines with hydrogen halide in acetone or aqueous acetone gave the corresponding 2-haloethylamines of general formula ImCH2CH(OH)CH2(+)-NH2CR1R2CR3R4X X-, where R1, R2, R3, R4 = H, Me, and X = F, Cl, Br, I. These 2-haloethylamines were evaluated as prodrugs of the parent aziridines. The rates of ring closure in aqueous solution at pH approximately 6 were found to increase with increasing methyl substitution and to depend on the nature of the leaving group (I approximately Br greater than Cl much greater than F). A competing reaction of ImCH2CH(OH)CH2+NH2CH2CH2X X- (X = Cl, Br) with aqueous HCO3- ions gives 3-[2-hyroxy-3-(2-nitro-1H-imidazol-1-yl)propyl]-2-oxazolidinone. The activities of these prodrugs as radiosensitizers or as bioreductively activated cytotoxins were consistent with the proportion converted to the parent aziridine during the course of the experiment. alpha-[[(2-Bromoethyl)amino]methyl]-2-nitro-1H-imidazole-1- ethanol (RB 6145, 10), the prodrug of alpha-[(1-aziridinyl)methyl]-2-nitro-1H-imidazole-1-ethanol (RSU-1069, 3), is identified as the most useful compound in terms of biological activity and rate of ring closure under physiological conditions

Structure of the SH3 domain of human osteoclast-stimulating factor at atomic resolution

International Nuclear Information System (INIS)

Chen, Liqing; Wang, Yujun; Wells, David; Toh, Diana; Harold, Hunt; Zhou, Jing; DiGiammarino, Enrico; Meehan, Edward J.

2006-01-01

The crystal structure of the SH3 domain of human osteoclast-stimulating factor has been determined and refined to the ultrahigh resolution of 1.07 Å. The structure at atomic resolution provides an accurate framework for structure-based design of its inhibitors. Osteoclast-stimulating factor (OSF) is an intracellular signaling protein, produced by osteoclasts themselves, that enhances osteoclast formation and bone resorption. It is thought to act via an Src-related signaling pathway and contains SH3 and ankyrin-repeat domains which are involved in protein–protein interactions. As part of a structure-based anti-bone-loss drug-design program, the atomic resolution X-ray structure of the recombinant human OSF SH3 domain (hOSF-SH3) has been determined. The domain, residues 12–72, yielded crystals that diffracted to the ultrahigh resolution of 1.07 Å. The overall structure shows a characteristic SH3 fold consisting of two perpendicular β-sheets that form a β-barrel. Structure-based sequence alignment reveals that the putative proline-rich peptide-binding site of hOSF-SH3 consists of (i) residues that are highly conserved in the SH3-domain family, including residues Tyr21, Phe23, Trp49, Pro62, Asn64 and Tyr65, and (ii) residues that are less conserved and/or even specific to hOSF, including Thr22, Arg26, Thr27, Glu30, Asp46, Thr47, Asn48 and Leu60, which might be key to designing specific inhibitors for hOSF to fight osteoporosis and related bone-loss diseases. There are a total of 13 well defined water molecules forming hydrogen bonds with the above residues in and around the peptide-binding pocket. Some of those water molecules might be important for drug-design approaches. The hOSF-SH3 structure at atomic resolution provides an accurate framework for structure-based design of its inhibitors

Understanding the role of BAR and SH3 domain-containing proteins in fungi

NARCIS (Netherlands)

Gkourtsa, A.

2017-01-01

This thesis addresses the role of SH3 and BAR domain-containing proteins in different fungal species. SH3 domains are small modules that mediate protein-protein interactions and BAR domains are dimerization domains with membrane binding and bending properties. It is known that the ScRvs167 protein

Synthesis, characterization and sorption properties of functionalized Cr-MIL-101-X (X=–F, –Cl, –Br, –CH3, –C6H4, –F2, –(CH3)2) materials

International Nuclear Information System (INIS)

Buragohain, Amlan; Couck, Sarah; Van Der Voort, Pascal; Denayer, Joeri F.M.; Biswas, Shyam

2016-01-01

Four existing and three new functionalized chromium terephthalates having MIL-101 topology and denoted as Cr-MIL-101-X (existing ones with X=–F, 1-F; –Cl, 2-Cl; –Br, 3-Br; –CH 3 , 4-CH 3 ; new ones with X=–C 6 H 4 , 5-C 6 H 4 ; –F 2 , 6-F 2 , –(CH 3 ) 2 , 7-(CH 3 ) 2 ) were synthesized under hydrothermal conditions. All the materials except 5-C 6 H 4 could be prepared by a general synthetic route, in which the mixtures of CrO 3 , H 2 BDC-X (BDC=1,4-benzenedicarboxylate) linkers, conc. HCl and water with a molar ratio of 1:1:3.9:222.2 were reacted at 180 °C for 144 h. Compared to the 144 h of synthesis time, three of the compounds, namely 1-Cl, 2-Br and 5-C 6 H 4 , could be prepared in much shorter reaction times (12–18 h at 180–210 °C). The materials possess high thermal stability up to 270–300 °C in an air atmosphere. The activated compounds exhibit significant porosity (S BET range: 1273–2135 m 2 g −1 ). At 0 °C and 1 bar, the CO 2 adsorption capacities of the compounds fall in the 1.7–2.9 mmol g −1 range. Compounds 1-F and 6-F 2 showed enhanced CO 2 uptake values compared to parent Cr-MIL-101. The benzene adsorption capacities of the compounds lie in the range of 66.2–139.5 molecules per unit cell at 50 °C and p/p 0 =0.35. The increased benzene uptake value of 1-F compared to un-functionalized Cr-MIL-101 and 4-CH 3 suggests that the fluorination has induced more hydrophobicity in Cr-MIL-101 as compared to the methylation. - Graphical abstract: Benzene adsorption by seven functionalized Cr-MIL-101-X metal-organic framework (MOF) materials Display Omitted - Highlights: • Seven functionalized Cr-MIL-101-X materials were synthesized solvothermally. • All Cr-MIL-101-X materials exhibited high thermal stability up to 270–300 °C in air. • All Cr-MIL-101-X compounds displayed considerable porosity towards N 2 , CO 2 and benzene. • Mono- and di-fluorinated Cr-MIL-101 materials showed enhanced CO 2 adsorption capacities. �

Dynamics of the F(-) + CH3I → HF + CH2I(-) Proton Transfer Reaction.

Science.gov (United States)

Zhang, Jiaxu; Xie, Jing; Hase, William L

2015-12-17

Direct chemical dynamics simulations, at collision energies Erel of 0.32 and 1.53 eV, were performed to obtain an atomistic understanding of the F(-) + CH3I reaction dynamics. There is only the F(-) + CH3I → CH3F + I(-) bimolecular nucleophilic substitution SN2 product channel at 0.32 eV. Increasing Erel to 1.53 eV opens the endothermic F(-) + CH3I → HF + CH2I(-) proton transfer reaction, which is less competitive than the SN2 reaction. The simulations reveal proton transfer occurs by two direct atomic-level mechanisms, rebound and stripping, and indirect mechanisms, involving formation of the F(-)···HCH2I complex and the roundabout. For the indirect trajectories all of the CH2I(-) is formed with zero-point energy (ZPE), while for the direct trajectories 50% form CH2I(-) without ZPE. Without a ZPE constraint for CH2I(-), the reaction cross sections for the rebound, stripping, and indirect mechanisms are 0.2 ± 0.1, 1.2 ± 0.4, and 0.7 ± 0.2 Å(2), respectively. Discarding trajectories that do not form CH2I(-) with ZPE reduces the rebound and stripping cross sections to 0.1 ± 0.1 and 0.7 ± 0.5 Å(2). The HF product is formed rotationally and vibrationally unexcited. The average value of J is 2.6 and with histogram binning n = 0. CH2I(-) is formed rotationally excited. The partitioning between CH2I(-) vibration and HF + CH2I(-) relative translation energy depends on the treatment of CH2I(-) ZPE. Without a CH2I(-) ZPE constraint the energy partitioning is primarily to relative translation with little CH2I(-) vibration. With a ZPE constraint, energy partitioning to CH2I(-) rotation, CH2I(-) vibration, and relative translation are statistically the same. The overall F(-) + CH3I rate constant at Erel of both 0.32 and 1.53 eV is in good agreement with experiment and negligibly affected by the treatment of CH2I(-) ZPE, since the SN2 reaction is the major contributor to the total reaction rate constant. The potential energy surface and reaction dynamics for F

CH(3)NH(3)PbI(3) perovskite / silicon tandem solar cells: characterization based optical simulations.

Science.gov (United States)

Filipič, Miha; Löper, Philipp; Niesen, Bjoern; De Wolf, Stefaan; Krč, Janez; Ballif, Christophe; Topič, Marko

2015-04-06

In this study we analyze and discuss the optical properties of various tandem architectures: mechanically stacked (four-terminal) and monolithically integrated (two-terminal) tandem devices, consisting of a methyl ammonium lead triiodide (CH(3)NH(3)PbI(3)) perovskite top solar cell and a crystalline silicon bottom solar cell. We provide layer thickness optimization guidelines and give estimates of the maximum tandem efficiencies based on state-of-the-art sub cells. We use experimental complex refractive index spectra for all involved materials as input data for an in-house developed optical simulator CROWM. Our characterization based simulations forecast that with optimized layer thicknesses the four-terminal configuration enables efficiencies over 30%, well above the current single-junction crystalline silicon cell record of 25.6%. Efficiencies over 30% can also be achieved with a two-terminal monolithic integration of the sub-cells, combined with proper selection of layer thicknesses.

Generation and relaxation of high rank coherences in AX3 systems in a selectively methionine labelled SH2 domain

International Nuclear Information System (INIS)

Kloiber, Karin; Fischer, Michael; Ledolter, Karin; Nagl, Michael; Schmid, Walther; Konrat, Robert

2007-01-01

The usefulness of selective isotope labelling patterns is demonstrated using the C-terminal SH2 domain of PLC-γ1 selectively 13 C labelled at methionine methyl groups. We demonstrate the generation and relaxation of coherences that are second rank in protons and first rank in carbons that derive from quadrupolar order in protons. The decay rates of second rank double quantum proton coherences are measured. These terms exhibit fewer channels for cross-correlated relaxation compared to single quantum coherences. Our results indicate the potential application of the measurement of high order proton coherences to the analysis of dynamics in methyl-bearing side chains

Three new shRNA expression vectors targeting the CYP3A4 coding sequence to inhibit its expression

Directory of Open Access Journals (Sweden)

Siyun Xu

2014-10-01

Full Text Available RNA interference (RNAi is useful for selective gene silencing. Cytochrome P450 3A4 (CYP3A4, which metabolizes approximately 50% of drugs in clinical use, plays an important role in drug metabolism. In this study, we aimed to develop a short hairpin RNA (shRNA to modulate CYP3A4 expression. Three new shRNAs (S1, S2 and S3 were designed to target the coding sequence (CDS of CYP3A4, cloned into a shRNA expression vector, and tested in different cells. The mixture of three shRNAs produced optimal reduction (55% in CYP3A4 CDS-luciferase activity in both CHL and HEK293 cells. Endogenous CYP3A4 expression in HepG2 cells was decreased about 50% at both mRNA and protein level after transfection of the mixture of three shRNAs. In contrast, CYP3A5 gene expression was not altered by the shRNAs, supporting the selectivity of CYP3A4 shRNAs. In addition, HepG2 cells transfected with CYP3A4 shRNAs were less sensitive to Ginkgolic acids, whose toxic metabolites are produced by CYP3A4. These results demonstrate that vector-based shRNAs could modulate CYP3A4 expression in cells through their actions on CYP3A4 CDS, and CYP3A4 shRNAs may be utilized to define the role of CYP3A4 in drug metabolism and toxicity.

A randomized, double-blind, crossover, placebo-controlled clinical trial to assess effects of the single ingestion of a tablet containing lactoferrin, lactoperoxidase, and glucose oxidase on oral malodor.

Science.gov (United States)

Nakano, Manabu; Shimizu, Eiju; Wakabayashi, Hiroyuki; Yamauchi, Koji; Abe, Fumiaki

2016-03-22

The main components of oral malodor have been identified as volatile sulfur compounds (VSCs) including hydrogen sulfide (H2S) and methyl mercaptan (CH3SH). VSCs also play an important role in the progression of periodontal disease. The aim of the present study was to assess the effects of the single ingestion of a tablet containing 20 mg of lactoferrin, 2.6 mg of lactoperoxidase, and 2.6 mg of glucose oxidase on VSCs in the mouth. Subjects with VSCs greater than the olfactory threshold in their mouth air ingested a test or placebo tablet in two crossover phases. The concentrations of VSCs were monitored at baseline and 10 and 30 min after ingestion of the tablets using portable gas chromatography. Thirty-nine subjects were included in the efficacy analysis based on a full analysis set (FAS). The concentrations of total VSCs and H2S at 10 min were significantly lower in the test group than in the placebo group (-0.246 log ng/10 ml [95 % CI -0.395 to -0.098], P = 0.002; -0.349 log ng/10 ml; 95 % CI -0.506 to -0.192; P oxidase has suppressive effects on oral malodor. This trial was registered with the University Hospital Medical Information Network Clinical Trial Registry (number: UMIN000015140 , date of registration: 16/09/2014).

Rate Constant for the Reaction CH3 + CH3 Yields C2H6 at T = 155 K and Model Calculation of the CH3 Abundance in the Atmospheres of Saturn and Neptune

Science.gov (United States)

Cody, Regina J.; Romani, Paul N.; Nesbitt, Fred L.; Iannone, Mark A.; Tardy, Dwight C.; Stief, Louis J.

2003-01-01

The column abundances of CH3 observed by the Infrared Space Observatory (ISO) satellite on Saturn and Neptune were lower than predicted by atmospheric photochemical models, especially for Saturn. It has been suggested that the models underestimated the loss of CH3 due to poor knowledge of the rate constant k of the CH3 + CH3 self-reaction at the low temperatures and pressures of these atmospheres. Motivated by this suggestion, we undertook a combined experimental and photochemical modeling study of the CH3 + CH3 reaction and its role in determining planetary CH3 abundances. In a discharge flow-mass spectrometer system, k was measured at T = 155 K and three pressures of He. The results in units of cu cm/molecule/s are k(0.6 Torr) = 6.82 x 10(exp -11), k(1.0 Torr) = 6.98 x 10(exp -11), and k(1.5 Torr) = 6.91 x 10(exp -11). Analytical expressions for k were derived that (1) are consistent with the present laboratory data at T = 155 K, our previous data at T = 202 K and 298 K, and those of other studies in He at T = 296-298 K and (2) have some theoretical basis to provide justification for extrapolation. The derived analytical expressions were then used in atmospheric photochemical models for both Saturn and Neptune. These model results reduced the disparity with observations of Saturn, but not with observations of Neptune. However, the disparity for Neptune is much smaller. The solution to the remaining excess CH3 prediction in the models relative to the ISO observations lies, to a large extent, elsewhere in the CH3 photochemistry or transport, not in the CH3 + CH3 rate.

Photostriction of CH3NH3PbBr3 Perovskite Crystals

KAUST Repository

Wei, Tzu-Chiao; Wang, Hsin-Ping; Li, Ting-You; Lin, Chun-Ho; Hsieh, Ying-Hui; Chu, Ying-Hao; He, Jr-Hau

2017-01-01

.e., photostriction). From these shifts, the photostrictive coefficient of CH3 NH3 PbBr3 is calculated as 2.08 × 10-8 m2 W-1 at room temperature under visible light illumination. The significant photostriction of CH3 NH3 PbBr3 is attributed to a combination

Abl N-terminal Cap stabilization of SH3 domain dynamics†

OpenAIRE

Chen, Shugui; Dumitrescu, Teodora Pene; Smithgall, Thomas E.; Engen, John R.

2008-01-01

Crystal structures and other biochemical data indicate that the N-terminal cap (NCap) region of the Abelson tyrosine kinase (c-Abl) is important for maintaining the downregulated conformation of the kinase domain. The exact contributions that NCap makes in stabilizing the various intramolecular interactions within c-Abl are less clear. While the NCap appears important for locking the SH3/SH2 domains to the back of the kinase domain, there may be other more subtle elements of regulation. Hydro...

The Products of the Thermal Decomposition of CH3CHO

Energy Technology Data Exchange (ETDEWEB)

Vasiliou, AnGayle; Piech, Krzysztof M.; Zhang, Xu; Nimlos, Mark R.; Ahmed, Musahid; Golan, Amir; Kostko, Oleg; Osborn, David L.; Daily, John W.; Stanton, John F.; Ellison, G. Barney

2011-04-06

We have used a heated 2 cm x 1 mm SiC microtubular (mu tubular) reactor to decompose acetaldehyde: CH3CHO + DELTA --> products. Thermal decomposition is followed at pressures of 75 - 150 Torr and at temperatures up to 1700 K, conditions that correspond to residence times of roughly 50 - 100 mu sec in the mu tubular reactor. The acetaldehyde decomposition products are identified by two independent techniques: VUV photoionization mass spectroscopy (PIMS) and infrared (IR) absorption spectroscopy after isolation in a cryogenic matrix. Besides CH3CHO, we have studied three isotopologues, CH3CDO, CD3CHO, and CD3CDO. We have identified the thermal decomposition products CH3(PIMS), CO (IR, PIMS), H (PIMS), H2 (PIMS), CH2CO (IR, PIMS), CH2=CHOH (IR, PIMS), H2O (IR, PIMS), and HC=CH (IR, PIMS). Plausible evidence has been found to support the idea that there are at least three different thermal decomposition pathways for CH3CHO: Radical decomposition: CH3CHO + DELTA --> CH3 + [HCO] --> CH3 + H + CO Elimination: CH3CHO + DELTA --> H2 + CH2=C=O. Isomerization/elimination: CH3CHO + DELTA --> [CH2=CH-OH] --> HC=CH + H2O. Both PIMS and IR spectroscopy show compelling evidence for the participation of vinylidene, CH2=C:, as an intermediate in the decomposition of vinyl alchohol: CH2=CH-OH + DELTA --> [CH2=C:] + H2O --> HC=CH + H2O.

The Impact of Hazardous Chemicals on Macrophages

Science.gov (United States)

2012-04-01

8217MetBis) * Parathion solution (Parat) * Perchloromethyl mercaptan CChSCl (PClMM) * Propyl chloroformate ClCOzCHzCHzCH3 (PropClF) * *Abbreviation...0.53 (J.!M) 3.4nM 13 Perchloromethyl mercaptan 9.05 1.81 9.05 14 Propyl chloroformate 8.7 5.53 87 22 DTRA Basic Research Grant HDTRAI-07- 1-0027...production of semiconductor devices like integrated circuits and also used in laser and light-emitting diodes (LEOs). Butyl chloroformate (ButCIF

Interaction with the Src homology (SH3-SH2) region of the Src-family kinase Hck structures the HIV-1 Nef dimer for kinase activation and effector recruitment.

Science.gov (United States)

Alvarado, John Jeff; Tarafdar, Sreya; Yeh, Joanne I; Smithgall, Thomas E

2014-10-10

HIV-1 Nef supports high titer viral replication in vivo and is essential for AIDS progression. Nef function depends on interactions with multiple host cell effectors, including Hck and other Src-family kinases. Here we describe the x-ray crystal structure of Nef in complex with the Hck SH3-SH2 regulatory region to a resolution of 1.86 Å. The complex crystallized as a dimer of complexes, with the conserved Nef PXXPXR motif engaging the Hck SH3 domain. A new intercomplex contact was found between SH3 Glu-93, and Nef Arg-105. Mutagenesis of Hck SH3 Glu-93 interfered with Nef·Hck complex formation and kinase activation in cells. The Hck SH2 domains impinge on the N-terminal region of Nef to stabilize a dimer conformation that exposes Asp-123, a residue critical for Nef function. Our results suggest that in addition to serving as a kinase effector for Nef, Hck binding may reorganize the Nef dimer for functional interaction with other signaling partners. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Interaction with the Src Homology (SH3-SH2) Region of the Src-family Kinase Hck Structures the HIV-1 Nef Dimer for Kinase Activation and Effector Recruitment*

Science.gov (United States)

Alvarado, John Jeff; Tarafdar, Sreya; Yeh, Joanne I.; Smithgall, Thomas E.

2014-01-01

HIV-1 Nef supports high titer viral replication in vivo and is essential for AIDS progression. Nef function depends on interactions with multiple host cell effectors, including Hck and other Src-family kinases. Here we describe the x-ray crystal structure of Nef in complex with the Hck SH3-SH2 regulatory region to a resolution of 1.86 Å. The complex crystallized as a dimer of complexes, with the conserved Nef PXXPXR motif engaging the Hck SH3 domain. A new intercomplex contact was found between SH3 Glu-93, and Nef Arg-105. Mutagenesis of Hck SH3 Glu-93 interfered with Nef·Hck complex formation and kinase activation in cells. The Hck SH2 domains impinge on the N-terminal region of Nef to stabilize a dimer conformation that exposes Asp-123, a residue critical for Nef function. Our results suggest that in addition to serving as a kinase effector for Nef, Hck binding may reorganize the Nef dimer for functional interaction with other signaling partners. PMID:25122770

Theoretical Insights Reveal Novel Motions in Csk's SH3 Domain That Control Kinase Activation.

Directory of Open Access Journals (Sweden)

Sulyman Barkho

Full Text Available The Src family of tyrosine kinases (SFKs regulate numerous aspects of cell growth and differentiation and are under the principal control of the C-terminal Src Kinase (Csk. Although Csk and SFKs share conserved kinase, SH2 and SH3 domains, they differ considerably in three-dimensional structure, regulatory mechanism, and the intrinsic kinase activities. Although the SH2 and SH3 domains are known to up- or down-regulate tyrosine kinase function, little is known about the global motions in the full-length kinase that govern these catalytic variations. We use a combination of accelerated Molecular Dynamics (aMD simulations and experimental methods to provide a new view of functional motions in the Csk scaffold. These computational studies suggest that high frequency vibrations in the SH2 domain are coupled through the N-terminal lobe of the kinase domain to motions in the SH3 domain. The effects of these reflexive movements on the kinase domain can be viewed using both Deuterium Exchange Mass Spectrometry (DXMS and steady-state kinetic methods. Removal of several contacts, including a crystallographically unobserved N-terminal segment, between the SH3 and kinase domains short-circuit these coupled motions leading to reduced catalytic efficiency and stability of N-lobe motifs within the kinase domain. The data expands the model of Csk's activation whereby separate domains productively interact with two diametrically opposed surfaces of the kinase domain. Such reversible transitions may organize the active structure of the tyrosine kinase domain of Csk.

Ion yields of laser aligned CH3I and CH3Br from multiple orbitals

NARCIS (Netherlands)

He, Lanhai; Pan, Yun; Yang, Yujun; Luo, Sizuo; Lu, Chunjing; Zhao, Huifang; Li, Dongxu; Song, Lele; Stolte, Steven; Ding, Dajun; Roeterdink, Wim G.

2016-01-01

We have measured the alignment influence on ion yields of CH3I and CH3Br molecules in the laser intensity regime from 1013 W/cm2 to 1015 W/cm2. The hexapole state-selection technique combined with laser induced alignment has been employed to obtain aligned (〈P2(cosθ)〉=0.7) and anti-aligned

Presolvated Electron Reactions with Methyl Acetoacetate: Electron Localization, Proton-Deuteron Exchange, and H-Atom Abstraction

Directory of Open Access Journals (Sweden)

Alex Petrovici

2014-09-01

Full Text Available Radiation-produced electrons initiate various reaction processes that are important to radiation damage to biomolecules. In this work, the site of attachment of the prehydrated electrons with methyl acetoacetate (MAA, CH3-CO-CH2-COOCH3 at 77 K and subsequent reactions of the anion radical (CH3-CO•−-CH2-COOCH3 in the 77 to ca. 170 K temperature range have been investigated in homogeneous H2O and D2O aqueous glasses by electron spin resonance (ESR spectroscopy. At 77 K, the prehydrated electron attaches to MAA forming the anion radical in which the electron is delocalized over the two carbonyl groups. This species readily protonates to produce the protonated electron adduct radical CH3-C(•OH-CH2-COOCH3. The ESR spectrum of CH3-C(•OH-CH2-COOCH3 in H2O shows line components due to proton hyperfine couplings of the methyl and methylene groups. Whereas, the ESR spectrum of CH3-C(•OH-CH2-COOCH3 in D2O glass shows only the line components due to proton hyperfine couplings of CH3 group. This is expected since the methylene protons in MAA are readily exchangeable in D2O. On stepwise annealing to higher temperatures (ca. 150 to 170 K, CH3-C(•OH-CH2-COOCH3 undergoes bimolecular H-atom abstraction from MAA to form the more stable radical, CH3-CO-CH•-COOCH3. Theoretical calculations using density functional theory (DFT support the radical assignments.

Presolvated electron reactions with methyl acetoacetate: electron localization, proton-deuteron exchange, and H-atom abstraction.

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Petrovici, Alex; Adhikary, Amitava; Kumar, Anil; Sevilla, Michael D

2014-09-01

Radiation-produced electrons initiate various reaction processes that are important to radiation damage to biomolecules. In this work, the site of attachment of the prehydrated electrons with methyl acetoacetate (MAA, CH3-CO-CH2-COOCH3) at 77 K and subsequent reactions of the anion radical (CH3-CO•--CH2-COOCH3) in the 77 to ca. 170 K temperature range have been investigated in homogeneous H2O and D2O aqueous glasses by electron spin resonance (ESR) spectroscopy. At 77 K, the prehydrated electron attaches to MAA forming the anion radical in which the electron is delocalized over the two carbonyl groups. This species readily protonates to produce the protonated electron adduct radical CH3-C(•)OH-CH2-COOCH3. The ESR spectrum of CH3-C(•)OH-CH2-COOCH3 in H2O shows line components due to proton hyperfine couplings of the methyl and methylene groups. Whereas, the ESR spectrum of CH3-C(•)OH-CH2-COOCH3 in D2O glass shows only the line components due to proton hyperfine couplings of CH3 group. This is expected since the methylene protons in MAA are readily exchangeable in D2O. On stepwise annealing to higher temperatures (ca. 150 to 170 K), CH3-C(•)OH-CH2-COOCH3 undergoes bimolecular H-atom abstraction from MAA to form the more stable radical, CH3-CO-CH•-COOCH3. Theoretical calculations using density functional theory (DFT) support the radical assignments.

Studies of the electron density in the highest occupied molecular orbitals of PH 3, PF 3 and P(CH 3) 3 by electron momentum spectroscopy and Hartree-Fock, MRSD-CI and DFT calculations

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Rolke, J.; Brion, C. E.

1996-06-01

The spherically averaged momentum profiles for the highest occupied molecular orbitals of PF 3 and P(CH 3) 3 have been obtained by electron momentum spectroscopy. The measurements provide a stringent test of basis set effects and the quality of ab-initio methods in the description of these larger molecular systems. As in previous work on the methyl-substituted amines, intuitive arguments fail to predict the correct amount of s- and p-type contributions to the momentum profile while delocalized molecular orbital concepts provide a more adequate description of the HOMOs. The experimental momentum profiles have been compared with theoretical momentum profiles calculated at the level of the target Hartree-Fock approximation with a range of basis sets. New Hartree-Fock calculations are also presented for the HOMO of PH 3 and compared to previously published experimental and theoretical momentum profiles. The experimental momentum profiles have further been compared to calculations at the level of the target Kohn-Sham approximation using density functional theory with the local density approximation and also with gradient corrected (non-local) exchange correlation potentials. In addition, total energies and dipole moments have been calculated for all three molecules by the various theoretical methods and compared to experimental values. Calculated 'density difference maps' show the regions where the HOMO momentum and position electron densities of PF 3 and P(CH 3) 3 change relative to the corresponding HOMO density of PH 3. The results suggest that methyl groups have an electron-attracting effect (relative to H) on the HOMO charge density in trimethyl phosphines. These conclusions are supported by a consideration of dipole moments and the 31P NMR chemical shifts for PH 3, PF 3 and P(CH 3) 3.

Comparison of the Fc fragment from a human IgG1 and its CH2, pFc', and tFc' subfragments. A study using reductive methylation and 13C NMR

International Nuclear Information System (INIS)

Jentoft, J.E.; Rayford, R.

1989-01-01

The Fc fragment of a human monoclonal IgG1 was compared with subfragments containing (a) the intact CH2 domain (CH2 fragment) or (b) the intact CH3 domain (pFc' and tFc' fragments). All fragments were reductively 13 C-methylated and their resulting dimethyllysyl resonances characterized in 0.1 M KCl as a function of pH by 13 C NMR spectroscopy. Seven resonances were characterized for the 18 lysine residues of the Fc fragment, eight for the 12 lysines of the CH2 fragment, and five each for the 9 lysines of the pFc' and the 6 lysines of the tFc' fragments, respectively. The multiplicity of resonances indicates that the lysine residues in each fragment exist in a variety of microenvironments and that the fragments are all highly structured. The correspondence between 6 of the 12 or 13 perturbed lysine residues in the Fc fragment and the smaller subfragments indicates that the conformation of the CH2 and CH3 domains is largely unchanged in the smaller fragments. However, in addition to three lysines at the CH2-CH3 domain interface, whose environments were known to be disrupted in the smaller fragments, three or four lysine residues have somewhat different properties in the Fc fragment and in the subfragments, indicating that some local perturbations are included in the domain structure in the subfragments

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

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

2003-10-01

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

Photoelectric characteristics of CH3NH3PbI3/p-Si heterojunction

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Yamei, Wu; Ruixia, Yang; Hanmin, Tian; Shuai, Chen

2016-05-01

Organic-inorganic hybrid perovskite CH3NH3PbI3 film is prepared on p-type silicon substrate using the one-step solution method to form a CH3NH3PbI3/p-Si heterojunction. The film morphology and structure are characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The photoelectric properties of the CH3NH3PbI3/p-Si heterojunction are studied by testing the current-voltage (I-V) with and without illumination and capacitance-voltage (C-V) characteristics. It turns out from the I-V curve without illumination that the CH3NH3PbI3/p-Si heterojunction has a rectifier feature with the rectification ratio over 70 at the bias of ±5 V. Also, there appears a photoelectric conversion phenomenon on this heterojunction with a short circuit current (Isc) of 0.16 μA and an open circuit voltage (Voc) of about 10 mV The high frequency C-V characteristic of the Ag/CH3NH3PbI3/p-Si heterojunction turns out to be similar to that of the metal-insulator-semiconductor (MIS) structure, and a parallel translation of the C-V curve along the forward voltage axis is found. This parallel translation means the existence of defects at the CH3NH3PbI3/p-Si interface and positive fixed charges in the CH3NH3PbI3 layer. The defects at the interface of the CH3NH3PbI3/p-Si heterojunction result in the dramatic decline of the Voc. Besides, the C-V test of CH3NH3PbI3 film shows a non-linear dielectric property and the dielectric value is about 4.64 as calculated. Project supported by the Hebei Province Natural Science Foundation of China (No. F2014202184) and the Tianjin Natural Science Foundation of China (No. 15JCZDJC37800).

Comparative Genomics and Disorder Prediction Identify Biologically Relevant SH3 Protein Interactions.

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2005-08-01

Full Text Available Protein interaction networks are an important part of the post-genomic effort to integrate a part-list view of the cell into system-level understanding. Using a set of 11 yeast genomes we show that combining comparative genomics and secondary structure information greatly increases consensus-based prediction of SH3 targets. Benchmarking of our method against positive and negative standards gave 83% accuracy with 26% coverage. The concept of an optimal divergence time for effective comparative genomics studies was analyzed, demonstrating that genomes of species that diverged very recently from Saccharomyces cerevisiae(S. mikatae, S. bayanus, and S. paradoxus, or a long time ago (Neurospora crassa and Schizosaccharomyces pombe, contain less information for accurate prediction of SH3 targets than species within the optimal divergence time proposed. We also show here that intrinsically disordered SH3 domain targets are more probable sites of interaction than equivalent sites within ordered regions. Our findings highlight several novel S. cerevisiae SH3 protein interactions, the value of selection of optimal divergence times in comparative genomics studies, and the importance of intrinsic disorder for protein interactions. Based on our results we propose novel roles for the S. cerevisiae proteins Abp1p in endocytosis and Hse1p in endosome protein sorting.

Comparative genomics and disorder prediction identify biologically relevant SH3 protein interactions.

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Pedro Beltrao

2005-08-01

Full Text Available Protein interaction networks are an important part of the post-genomic effort to integrate a part-list view of the cell into system-level understanding. Using a set of 11 yeast genomes we show that combining comparative genomics and secondary structure information greatly increases consensus-based prediction of SH3 targets. Benchmarking of our method against positive and negative standards gave 83% accuracy with 26% coverage. The concept of an optimal divergence time for effective comparative genomics studies was analyzed, demonstrating that genomes of species that diverged very recently from Saccharomyces cerevisiae(S. mikatae, S. bayanus, and S. paradoxus, or a long time ago (Neurospora crassa and Schizosaccharomyces pombe, contain less information for accurate prediction of SH3 targets than species within the optimal divergence time proposed. We also show here that intrinsically disordered SH3 domain targets are more probable sites of interaction than equivalent sites within ordered regions. Our findings highlight several novel S. cerevisiae SH3 protein interactions, the value of selection of optimal divergence times in comparative genomics studies, and the importance of intrinsic disorder for protein interactions. Based on our results we propose novel roles for the S. cerevisiae proteins Abp1p in endocytosis and Hse1p in endosome protein sorting.

A Discovery Strategy for Selective Inhibitors of c-Src in Complex with the Focal Adhesion Kinase SH3/SH2-binding Region.

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Moroco, Jamie A; Baumgartner, Matthew P; Rust, Heather L; Choi, Hwan Geun; Hur, Wooyoung; Gray, Nathanael S; Camacho, Carlos J; Smithgall, Thomas E

2015-08-01

The c-Src tyrosine kinase co-operates with the focal adhesion kinase to regulate cell adhesion and motility. Focal adhesion kinase engages the regulatory SH3 and SH2 domains of c-Src, resulting in localized kinase activation that contributes to tumor cell metastasis. Using assay conditions where c-Src kinase activity required binding to a tyrosine phosphopeptide based on the focal adhesion kinase SH3-SH2 docking sequence, we screened a kinase-biased library for selective inhibitors of the Src/focal adhesion kinase peptide complex versus c-Src alone. This approach identified an aminopyrimidinyl carbamate compound, WH-4-124-2, with nanomolar inhibitory potency and fivefold selectivity for c-Src when bound to the phospho-focal adhesion kinase peptide. Molecular docking studies indicate that WH-4-124-2 may preferentially inhibit the 'DFG-out' conformation of the kinase active site. These findings suggest that interaction of c-Src with focal adhesion kinase induces a unique kinase domain conformation amenable to selective inhibition. © 2014 John Wiley & Sons A/S.

Functional analysis of SH3 domain containing ring finger 2 during the myogenic differentiation of quail myoblast cells

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Si Won Kim

2017-08-01

Full Text Available Objective Owing to the public availability of complete genome sequences, including avian species, massive bioinformatics analyses may be conducted for computational gene prediction and the identification of gene regulatory networks through various informatics tools. However, to evaluate the biofunctional activity of a predicted target gene, in vivo and in vitro functional genomic analyses should be a prerequisite. Methods Due to a lack of quail genomic sequence information, we first identified the partial genomic structure and sequences of the quail SH3 domain containing ring finger 2 (SH3RF2 gene. Subsequently, SH3RF2 was knocked out using clustered regularly interspaced short palindromic repeat/Cas9 technology and single cell-derived SH3RF2 mutant sublines were established to study the biofunctional activity of SH3RF2 in quail myoblast (QM7 cells during muscle differentiation. Results Through a T7 endonuclease I assay and genotyping analysis, we established an SH3RF2 knockout (KO QM7#4 subline with 61 and 155 nucleotide deletion mutations in SH3RF2. After the induction of myotube differentiation, the expression profiles were analyzed and compared between regular QM7 and SH3RF2 KO QM7#4 cells by global RNA sequencing and bioinformatics analysis. Conclusion We did not detect any statistically significant role of SH3RF2 during myotube differentiation in QM7 myoblast cells. However, additional experiments are necessary to examine the biofunctional activity of SH3RF2 in cell proliferation and muscle growth.

CH_3Cl, CH_2Cl_2, CHCl_3, and CCl_4: Infrared spectra, radiative efficiencies, and global warming potentials

International Nuclear Information System (INIS)

Wallington, Timothy J.; Pivesso, Bruno Pasquini; Lira, Alane Moura; Anderson, James E.; Nielsen, Claus Jørgen; Andersen, Niels Højmark; Hodnebrog, Øivind

2016-01-01

Infrared spectra for the title compounds were measured experimentally in 700 Torr of air at 295 K and systematically modeled in B3LYP, M06-2X and MP2 calculations employing various basis sets. Calibrated infrared spectra over the wavenumber range 600–3500 cm"−"1 are reported and combined with literature data to provide spectra for use in experimental studies and radiative transfer calculations. Integrated absorption cross sections are (units of cm"−"1 molecule"−"1): CH_3Cl, 660–780 cm"−"1, (3.89±0.19)×10"−"1"8; CH_2Cl_2, 650–800 cm"−"1, (2.16±0.11)×10"−"1"7; CHCl_3, 720–810 cm"−"1, (4.08±0.20)×10"−"1"7; and CCl_4, 730–825 cm"−"1, (6.30±0.31)×10"−"1"7. CH_3Cl, CH_2Cl_2, CHCl_3, and CCl_4 have radiative efficiencies of 0.004, 0.028, 0.070, and 0.174 W m"−"2 ppb"−"1 and global warming potentials (100 year horizon) of 5, 8, 15, and 1775, respectively. Quantum chemistry calculations generally predict larger band intensities than the experimental values. The best agreement with experiments is obtained in MP2(Full) calculations employing basis sets of at least triple-zeta quality augmented by diffuse functions. The B3LYP functional is found ill-suited for calculating vibrational frequencies and infrared intensities of halocarbons. - Highlights: • Infrared spectra reported for CH_3Cl, CH_2Cl_2, CHCl_3, and CCl_4. • REs of CH_3Cl, CH_2Cl_2, CHCl_3, and CCl_4 are 0.004, 0.028, 0.070, and 0.174 W m"−"2 ppb"−"1, respectively. • GWPs of CH_3Cl, CH_2Cl_2, CHCl_3, and CCl_4 are 5, 8, 15, and 1775, respectively.

Synthesis and biochemical evaluation of tritium-labeled 1-methyl-N-(8-methyl-8-azabicyclo[3.2.1]oct-3-yl)-1H-indazole-3-carboxa mide, a useful radioligand for 5HT3 receptors

International Nuclear Information System (INIS)

Robertson, D.W.; Bloomquist, W.; Cohen, M.L.; Reid, L.R.; Schenck, K.; Wong, D.T.

1990-01-01

The advent of potent, highly selective 5HT3 receptor antagonists has stimulated considerable interest in 5HT3 receptor mediated physiology and pharmacology. To permit detailed biochemical studies regarding interaction of the indazole class of serotonin (5HT) antagonists with 5HT3 receptors in multiple tissues, we synthesized 1-methyl-N-(8-methyl-8-azabicyclo[3.2.1]oct-3-yl)-1H-indazole- 3-carboxamide (LY278584, compound 9) in high specific activity, tritium-labeled form. This radioligand was selected as a synthetic target because of its potency as a 5HT3-receptor antagonist, its selectivity for this receptor viz a viz other 5HT-receptor subtypes, and the ability to readily incorporate three tritia via the indazole N-CH3 substituent. Alkylation of N-(8-methyl-8-azabicyclo[3.2.1]oct-3-yl)-1H-indazole-3-carboxamide (8) with sodium hydride and tritium-labeled iodomethane, followed by HPLC purification, resulted in [3H]-9 with a radiochemical purity of 99% and a specific activity of 80.5 Ci/mmol. This radioligand bound with high affinity to a single class of saturable recognition sites in membranes isolated from cerebral cortex of rat brain. The Kd was 0.69 nM and the Bmax was 16.9 fmol/mg of protein. The specific binding was excellent, and accounted for 83-93% of total binding at concentrations of 2 nM or less. The potencies of known 5HT3-receptor antagonists as inhibitors of [3H]-9 binding correlated well with their pharmacological receptor affinities as antagonists of 5HT-induced decreases in heart rate and contraction of guinea pig ileum, suggesting the central recognition site for this radioligand may be extremely similar to or identical with peripheral 5HT3 receptors

Betaine Phosphate (CH3)3N+CH2COO-.H3PO4 Modification Using D2O

International Nuclear Information System (INIS)

Saryati; Ridwan; Deswita; Sugiantoro, Sugik

2002-01-01

Betaine fosfate (CH 3 ) 3 N + CH 2 COO - .H 3 PO 4 modification by using D 2 O has been studied. This modification was carried out by slowly evaporation the saturated Betaine phosphat in the D 2 O solution in the dry box at 40 o C, until the dry crystal were formed. Based on the NMR data, can be concluded that the exchange process with D has been runed well and Betaine phosphate-D (CH 3 ) 3 N + CH 2 COO - .H 3 PO 4 has been resulted. From the X-ray diffraction pattern data can be concluded that there are a deference in the crystal structure between Betaine phosphate and Betaine phosphate modification result. From the Differential Scanning Colorimeter (DSC) diagram at the range temperature from 30 o C to 250 o C, can be shown that the Betaine phosphate-H has two endothermic transition phase, at 99 o C with a very little adsorbed calor and at 221.50 o C with -26.75 cal/g. Modified Betaine phosphate has also two endothermic transition phase, at 99.86 o C with -1.94 cal/g and at 171.01 o C with -3.48 cal/g. It can be conclosed that the D atom substitution on the H atoms in Betaine phosphate, to change the crystal and the endothermic fase temperature and energy

Theoretical investigation of the oxidation pathways of the Cl-initiated reaction of 2-methyl-3-buten-2-ol

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Zhang, Weichao; Zhang, Dongju

2012-12-01

The mechanism and products of the reaction of 2-methyl-3-buten-2-ol (MBO232) with Cl atoms in the presence of O2 have been elucidated by performing high-level quantum chemistry calculations. The geometries of the reactants, intermediates, transition states, and products are optimized at the MP2(full)/6-311G(d, p) level, and their single-point energies are refined at the CCSD(T)/6-311 + G(d, p) level. The potential energy surface profiles have been constructed at the CCSD(T)/6-311 + G(d, p)//MP2(full)/6-311G(d, p) + 0.95 × ZPE level of theory, and the possible channels involved in the reaction are also discussed. The calculations indicate that the reaction predominantly proceeds via the addition of Cl atoms to the double bond rather than the direct abstraction of the H atoms in MBO232. The nascent adducts (CH3)2C(OH)CHCH2Cl (IM1) and (CH3)2C(OH)CHClCH2 (IM2) do not undergo subsequent isomerization and dissociation reactions, but rather react with O2. The theoretical results show that the major products are CH2ClCHO and CH3C(O)CH3 for the reaction of MBO232 + Cl in the presence of O2, which is in good agreement with the experimental finding.

In vivo binding properties of SH2 domains from GTPase-activating protein and phosphatidylinositol 3-kinase.

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Cooper, J A; Kashishian, A

1993-01-01

We have used a transient expression system and mutant platelet-derived growth factor (PDGF) receptors to study the binding specificities of the Src homology 2 (SH2) regions of the Ras GTPase-activator protein (GAP) and the p85 alpha subunit of phosphatidylinositol 3-kinase (PI3 kinase). A number of fusion proteins, each tagged with an epitope allowing recognition by a monoclonal antibody, were expressed at levels comparable to those of endogenous GAP. Fusion proteins containing the central SH2-SH3-SH2 region of GAP or the C-terminal region of p85 alpha, which includes two SH2 domains, bound to PDGF receptors in response to PDGF stimulation. Both fusion proteins showed the same requirements for tyrosine phosphorylation sites in the PDGF receptor as the full-length proteins from which they were derived, i.e., binding of the GAP fusion protein was reduced by mutation of Tyr-771, and binding of the p85 fusion protein was reduced by mutation of Tyr-740, Tyr-751, or both residues. Fusion proteins containing single SH2 domains from either GAP or p85 alpha did not bind detectably to PDGF receptors in this system, suggesting that two SH2 domains in a single polypeptide cooperate to raise the affinity of binding. The sequence specificities of individual SH2 domains were deduced from the binding properties of fusion proteins containing one SH2 domain from GAP and another from p85. The results suggest that the C-terminal GAP SH2 domain specifies binding to Tyr-771, the C-terminal p85 alpha SH2 domain binds to either Tyr-740 or Tyr-751, and each protein's N-terminal SH2 domain binds to unidentified phosphorylation sites.(ABSTRACT TRUNCATED AT 250 WORDS) Images PMID:8382774

Photolysis of CH3CHO at 248 nm: Evidence of triple fragmentation from primary quantum yield of CH3 and HCO radicals and H atoms

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Morajkar, Pranay; Bossolasco, Adriana; Schoemaecker, Coralie; Fittschen, Christa

2014-06-01

Radical quantum yields have been measured following the 248 nm photolysis of acetaldehyde, CH3CHO. HCO radical and H atom yields have been quantified by time resolved continuous wave Cavity Ring Down Spectroscopy in the near infrared following their conversion to HO2 radicals by reaction with O2. The CH3 radical yield has been determined using the same technique following their conversion into CH3O2. Absolute yields have been deduced for HCO radicals and H atoms through fitting of time resolved HO2 profiles, obtained under various O2 concentrations, to a complex model, while the CH3 yield has been determined relative to the CH3 yield from 248 nm photolysis of CH3I. Time resolved HO2 profiles under very low O2 concentrations suggest that another unknown HO2 forming reaction path exists in this reaction system besides the conversion of HCO radicals and H atoms by reaction with O2. HO2 profiles can be well reproduced under a large range of experimental conditions with the following quantum yields: CH3CHO + hν248nm → CH3CHO*, CH3CHO* → CH3 + HCO ϕ1a = 0.125 ± 0.03, CH3CHO* → CH3 + H + CO ϕ1e = 0.205 ± 0.04, CH3CHO*{to 2pc{rArrfill}}limits^{o2}CH3CO + HO2 ϕ1f = 0.07 ± 0.01. The CH3O2 quantum yield has been determined in separate experiments as φ_{CH3} = 0.33 ± 0.03 and is in excellent agreement with the CH3 yields derived from the HO2 measurements considering that the triple fragmentation (R1e) is an important reaction path in the 248 nm photolysis of CH3CHO. From arithmetic considerations taking into account the HO2 and CH3 measurements we deduce a remaining quantum yield for the molecular pathway: CH3CHO* → CH4 + CO ϕ1b = 0.6. All experiments can be consistently explained with absence of the formerly considered pathway: CH3CHO* → CH3CO + H ϕ1c = 0.

C-11 production with MC-50 cyclotron and synthesis of L-[11C-methyl] methionine

International Nuclear Information System (INIS)

Kim, Sang Wook; Hur, Min Goo; Yang, Seung Dae; Ahn, Soon Hyuk; Chun, Kweon Soo

2003-01-01

L-[ 11 C-methyl] methionine was prepared via no-carrier-added(nca) fast S-alkylation of L-homocysteine with [ 11 C]CH 3 I using solid support (Al 2 O 3 /KF)at room temperature in ethanol. The radiochemical yield of methylation was 90.2%. After reaction, no radiochemical impurity was detected but traces of L-homocysteine precursor were monitored by UV detector. The purification was archived by passing successively through a C 18 and alumina sep-pak. the radiochemical purity of L-[ 11 C-methyl] methionine was over 98% after purification and total elapsed time to prepare was 10min from [ 11 C]CH 3 I delivery

Millimeter Wave Spectrum of the Two Monosulfur Derivatives of Methyl Formate: s- and O-Methyl Thioformate, in the Ground and the First Excited Torsional States

Science.gov (United States)

Jabri, Atef; Motiyenko, R. A.; Margulès, L.; Guillemin, J.-C.; Alekseev, E. A.; Kleiner, Isabelle; Tercero, Belén; Cernicharo, Jose

2017-06-01

Methyl formate CH_{3}OC(O)H is a relatively abundant component of the interstellar medium (ISM). Thus, we decided to study its sulfur derivatives as they can be reasonably proposed for detection in the ISM. In fact there is two relatively stable isomers for methyl thioformate, S-Methyl thioformate CH_{3}SC(O)H and O-Methyl thiofomate CH_{3}OC(S)H. Theoretical investigations on these molecules have been done recently by Senent et al.. Previous experimental investigations were performed only for the S-Methyl thioformate in the 10-41 GHz spectral range by Jones et al. and Caminati et al.. For the present study both isomers were synthesized and the millimeter wave spectrum was then recorded for the first time from 150 to 660 GHz with the Lille's spectrometer based on solid-state sources. The internal rotation effect on the millimeter wave spectra is not the same for these two molecules because the barrier height to internal rotation is relatively low for the S- isomer (V_{3} ≈ 140 \\wn) and rather high for the O- isomer (V_{3} ≈ 700 \\wn). Analysis of the ground and excited torsional states performed with the BELGI-C_{s} code will be presented and discussed. We will provide the search for methyl thioformate in different sources. E. Chruchwell, G. Winnewisser, A&A, 45, 229 (1975) M. L. Senent, C. Puzzarini, M. Hochlaf, R. Dominguez-Gomez, and M. Carvajal, J. Chem. Phys., 141, 104303 (2014) G. I. L. Jones, D. G. Lister, N. L. Owen, J. Mol. Spectrosc., 60, 348 (1976) W. Caminati, B. P. V. Eijck, D. G. Lister, J. Mol. Spectrosc., 90, 15 (1981) J. T. Hougen, I. Kleiner, and M. Godefroid, J. Mol. Spectrosc. 163, 559 (1994)

Protection against 1-methyl-4-phenyl pyridinium-induced neurotoxicity in human neuroblastoma SH-SY5Y cells by Soyasaponin I by the activation of the phosphoinositide 3-kinase/AKT/GSK3β pathway.

Science.gov (United States)

Guo, Zheng; Cao, Wei; Zhao, Shifeng; Han, Zengtai; Han, Boxiang

2016-07-06

Parkinson's disease (PD) can be ascribed to the progressive and selective loss of dopaminergic neurons in the substantia nigra pars compacta, and thus molecules with neuroprotective ability may have therapeutic value against PD. In the current study, the neuroprotective effects and underlying mechanisms of Soyasaponin I (Soya-I), a naturally occurring triterpene extracted from a widely used ingredient in many foods, such as Glycine max (soybean), were evaluated in a widely used cellular PD model in which neurotoxicity was induced by 1-methyl-4-phenyl pyridinium (MPP) in cultured SH-SY5Y cells. We found that Soya-I at 10-40 μM considerably protected against MPP-induced neurotoxicity as evidenced by an increase in cell viability, a decrease in lactate dehydrogenase release, and a reduction in apoptotic nuclei. Moreover, Soya-I effectively inhibited the elevated intracellular accumulation of reactive oxygen species as well as the Bax/Bcl-2 ratio caused by MPP. Most importantly, Soya-I markedly reversed the inhibition of protein expression of phosphorylated AKT and phosphorylated GSK3β caused by MPP. LY294002, the specific inhibitor of phosphoinositide 3-kinase, significantly abrogated the upregulated phosphorylated AKT and phosphorylated GSK3β offered by Soya-I, suggesting that the neuroprotection of Soya-I was mainly dependent on the activation of the phosphoinositide 3-kinase/AKT/GSK3β signaling pathway. The results taken together indicate that Soya-I may be a potential candidate for further preclinical study aimed at the prevention and treatment of PD.

Measurement of Activity Coefficients at Infinite Dilution for Alcohols in [BMIM][CH3SO4] using HS-SPME/GC-FID

Directory of Open Access Journals (Sweden)

A. M. Elias

Full Text Available ABSTRACT The activity coefficient at infinite dilution (&IN1 and distribution ratios at infinite dilution (&IN2 were determined for alkanols (methanol, ethanol, 1-propanol, 1-butanol, 2-butanol, and 2-methyl-2-propanol in the ionic liquid (IL 1-butyl-3-methylimidazolium methyl sulfate ([BMIM][CH3SO4] by HS-SPME (Headspace - Solid Phase Micro Extraction at four temperatures (298.15, 313.15, 333.15, and 353.15K using headspace - solid phase microextraction (SPME-HS. The results showed significant agreement with literature data. In addition, partial molar excess enthalpies at infinite dilution (&IN3, excess Gibbs energies (&IN4, and excess entropies (&IN5 were calculated from the (&IN6 values.

In Utero Exposure to Dietary Methyl Nutrients and Breast Cancer Risk in Offspring

Science.gov (United States)

2010-09-01

distribution unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT Lipotropes (methionine, choline, folate , and vitamin B12) are dietary methyl donors and...Lipotropes are methyl group (CH3) containing essential nutrients (methionine, choline, folate , and vitamin B12) and are important methyl donors...is highly dependent on methyl donors and cofactors (11, 17). The coenzymes necessary for DNA methylation reactions include folate , vitamin B12, and

Solution structure, dynamics and thermodynamics of the three SH3 domains of CD2AP

Energy Technology Data Exchange (ETDEWEB)

Roldan, Jose L. Ortega [Universidad de Granada, Departamento de Quimica Fisica e Instituto de Biotecnologia, Facultad de Ciencias (Spain); Blackledge, Martin [Institut de Biologie Structurale Jean-Pierre Ebel, CEA, CNRS, UJF UMR 5075, Protein Dynamics and Flexibility by NMR (France); Nuland, Nico A. J. van, E-mail: nvnuland@vub.ac.be [Vrije Universiteit Brussel, Structural Biology Brussels (Belgium); Azuaga, Ana I. [Universidad de Granada, Departamento de Quimica Fisica e Instituto de Biotecnologia, Facultad de Ciencias (Spain)

2011-06-15

CD2 associated protein (CD2AP) is an adaptor protein that plays an important role in cell to cell union needed for the kidney function. It contains three N-terminal SH3 domains that are able to interact among others with CD2, ALIX, c-Cbl and Ubiquitin. To understand the role of the individual SH3 domains of this adaptor protein we have performed a complete structural, thermodynamic and dynamic characterization of the separate domains using NMR and DSC. The energetic contributions to the stability and the backbone dynamics have been related to the structural features of each domain using the structure-based FoldX algorithm. We have found that the N-terminal SH3 domain of both adaptor proteins CD2AP and CIN85 are the most stable SH3 domains that have been studied until now. This high stability is driven by a more extensive network of intra-molecular interactions. We believe that this increased stabilization of N-terminal SH3 domains in adaptor proteins is crucial to maintain the necessary conformation to establish the proper interactions critical for the recruitment of their natural targets.

Chloroacetone photodissociation at 193 nm and the subsequent dynamics of the CH3C(O)CH2 radical—an intermediate formed in the OH + allene reaction en route to CH3 + ketene

Science.gov (United States)

Alligood, Bridget W.; FitzPatrick, Benjamin L.; Szpunar, David E.; Butler, Laurie J.

2011-02-01

We use a combination of crossed laser-molecular beam experiments and velocity map imaging experiments to investigate the primary photofission channels of chloroacetone at 193 nm; we also probe the dissociation dynamics of the nascent CH3C(O)CH2 radicals formed from C-Cl bond fission. In addition to the C-Cl bond fission primary photodissociation channel, the data evidence another photodissociation channel of the precursor, C-C bond fission to produce CH3CO and CH2Cl. The CH3C(O)CH2 radical formed from C-Cl bond fission is one of the intermediates in the OH + allene reaction en route to CH3 + ketene. The 193 nm photodissociation laser allows us to produce these CH3C(O)CH2 radicals with enough internal energy to span the dissociation barrier leading to the CH3 + ketene asymptote. Therefore, some of the vibrationally excited CH3C(O)CH2 radicals undergo subsequent dissociation to CH3 + ketene products; we are able to measure the velocities of these products using both the imaging and scattering apparatuses. The results rule out the presence of a significant contribution from a C-C bond photofission channel that produces CH3 and COCH2Cl fragments. The CH3C(O)CH2 radicals are formed with a considerable amount of energy partitioned into rotation; we use an impulsive model to explicitly characterize the internal energy distribution. The data are better fit by using the C-Cl bond fission transition state on the S1 surface of chloroacetone as the geometry at which the impulsive force acts, not the Franck-Condon geometry. Our data suggest that, even under atmospheric conditions, the reaction of OH with allene could produce a small branching to CH3 + ketene products, rather than solely producing inelastically stabilized adducts. This additional channel offers a different pathway for the OH-initiated oxidation of such unsaturated volatile organic compounds, those containing a C=C=C moiety, than is currently included in atmospheric models.

Infrared absorption of CH3OSO and CD3OSO radicals produced upon photolysis of CH3OS(O)Cl and CD3OS(O)Cl in p-H2 matrices

International Nuclear Information System (INIS)

Lee, Yu-Fang; Kong, Lin-Jun; Lee, Yuan-Pern

2012-01-01

Irradiation at 239 ± 20 nm of a p-H 2 matrix containing methoxysulfinyl chloride, CH 3 OS(O)Cl, at 3.2 K with filtered light from a medium-pressure mercury lamp produced infrared (IR) absorption lines at 3028.4 (attributable to ν 1 , CH 2 antisymmetric stretching), 2999.5 (ν 2 , CH 3 antisymmetric stretching), 2950.4 (ν 3 , CH 3 symmetric stretching), 1465.2 (ν 4 , CH 2 scissoring), 1452.0 (ν 5 , CH 3 deformation), 1417.8 (ν 6 , CH 3 umbrella), 1165.2 (ν 7 , CH 3 wagging), 1152.1 (ν 8 , S=O stretching mixed with CH 3 rocking), 1147.8 (ν 9 , S=O stretching mixed with CH 3 wagging), 989.7 (ν 10 , C-O stretching), and 714.5 cm -1 (ν 11 , S-O stretching) modes of syn-CH 3 OSO. When CD 3 OS(O)Cl in a p-H 2 matrix was used, lines at 2275.9 (ν 1 ), 2251.9 (ν 2 ), 2083.3 (ν 3 ), 1070.3 (ν 4 ), 1056.0 (ν 5 ), 1085.5 (ν 6 ), 1159.7 (ν 7 ), 920.1 (ν 8 ), 889.0 (ν 9 ), 976.9 (ν 10 ), and 688.9 (ν 11 ) cm -1 appeared and are assigned to syn-CD 3 OSO; the mode numbers correspond to those used for syn-CH 3 OSO. The assignments are based on the photolytic behavior and a comparison of observed vibrational wavenumbers, infrared intensities, and deuterium isotopic shifts with those predicted with the B3P86/aug-cc-pVTZ method. Our results extend the previously reported four transient IR absorption bands of gaseous syn-CH 3 OSO near 2991, 2956, 1152, and 994 cm -1 to 11 lines, including those associated with C-O, O-S, and S=O stretching modes. Vibrational wavenumbers of syn-CD 3 OSO are new. These results demonstrate the advantage of a diminished cage effect of solid p-H 2 such that the Cl atom, produced via UV photodissociation of CH 3 OS(O)Cl in situ, might escape from the original cage to yield isolated CH 3 OSO radicals.

Infrared absorption of CH3OSO and CD3OSO radicals produced upon photolysis of CH3OS(O)Cl and CD3OS(O)Cl in p-H2 matrices.

Science.gov (United States)

Lee, Yu-Fang; Kong, Lin-Jun; Lee, Yuan-Pern

2012-03-28

Irradiation at 239 ± 20 nm of a p-H(2) matrix containing methoxysulfinyl chloride, CH(3)OS(O)Cl, at 3.2 K with filtered light from a medium-pressure mercury lamp produced infrared (IR) absorption lines at 3028.4 (attributable to ν(1), CH(2) antisymmetric stretching), 2999.5 (ν(2), CH(3) antisymmetric stretching), 2950.4 (ν(3), CH(3) symmetric stretching), 1465.2 (ν(4), CH(2) scissoring), 1452.0 (ν(5), CH(3) deformation), 1417.8 (ν(6), CH(3) umbrella), 1165.2 (ν(7), CH(3) wagging), 1152.1 (ν(8), S=O stretching mixed with CH(3) rocking), 1147.8 (ν(9), S=O stretching mixed with CH(3) wagging), 989.7 (ν(10), C-O stretching), and 714.5 cm(-1) (ν(11), S-O stretching) modes of syn-CH(3)OSO. When CD(3)OS(O)Cl in a p-H(2) matrix was used, lines at 2275.9 (ν(1)), 2251.9 (ν(2)), 2083.3 (ν(3)), 1070.3 (ν(4)), 1056.0 (ν(5)), 1085.5 (ν(6)), 1159.7 (ν(7)), 920.1 (ν(8)), 889.0 (ν(9)), 976.9 (ν(10)), and 688.9 (ν(11)) cm(-1) appeared and are assigned to syn-CD(3)OSO; the mode numbers correspond to those used for syn-CH(3)OSO. The assignments are based on the photolytic behavior and a comparison of observed vibrational wavenumbers, infrared intensities, and deuterium isotopic shifts with those predicted with the B3P86∕aug-cc-pVTZ method. Our results extend the previously reported four transient IR absorption bands of gaseous syn-CH(3)OSO near 2991, 2956, 1152, and 994 cm(-1) to 11 lines, including those associated with C-O, O-S, and S=O stretching modes. Vibrational wavenumbers of syn-CD(3)OSO are new. These results demonstrate the advantage of a diminished cage effect of solid p-H(2) such that the Cl atom, produced via UV photodissociation of CH(3)OS(O)Cl in situ, might escape from the original cage to yield isolated CH(3)OSO radicals.

Electron energy loss spectroscopy of CH3N2CH3 adsorbed on Ni(100), Ni(111), Cr(100), Cr(111)

International Nuclear Information System (INIS)

Schulz, M.A.

1985-07-01

A study of the adsorption of CH 3 N 2 CH 3 on Ni(100), Ni(111), Cr(100), and Cr(111) using high resolution electron energy loss spectroscopy (EELS) is presented. Under approximately the same conditions of coverage, the vibrational spectra of CH 3 N 2 CH 3 on these four surfaces are quite distinct from one another, implying that the CH 3 N 2 CH 3 -substrate interaction is very sensitive to the physical and electronic structure of each surface. In addition to the room temperature studies, the evolution of surface species on the Ni(100) surface in the temperature range 300 to 425 K was studied. Analysis of the Ni(100) spectra indicates that molecular adsorption, probably through the N lone pair, occurs at room temperature. Spectra taken after annealing the CH 3 N 2 CH 3 -Ni(100) surfaces indicate that CH and CN bond scission occurred at the elevated temperatures. Decomposition of CH 3 N 2 CH 3 takes place on the Ni(111), Cr(100), and Cr(111) surfaces at room temperature, as evidenced by the intensity of the carbon-metal stretch in the corresponding spectra. Possible identities of coadsorbed dissociation products are considered. The stable coverage of surface species on all four surfaces at 300 K is less than one monolayer. A general description of an electron energy loss (EEL) spectrometer is given. Followed by a more specific discussion of some recent modifications to the EEL monochromator assembly used in this laboratory. Both the previous configuration of our monochromator and the new version are briefly described, as an aid to understanding the motivation for the changes as well as the differences in operation of the two versions. For clarity, the new monochromator design is referred to as variable pass, while the previous design is referred to as double pass. A modified tuning procedure for the new monochromator is also presented. 58 refs., 11 figs

Production of gaseous radiotracers CH{sub 3}I and I{sub 2} through Na{sup 123}I salt

Energy Technology Data Exchange (ETDEWEB)

Candeiro, R.E.M., E-mail: ricardocandeiro@cnen.gov.b [Comissao Nacional de Energia Nuclear (DIFOR/CNEN-CE), Fortaleza, CE (Brazil). Distrito de Fortaleza; Brandao, L.B. [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Pereira, W.P. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil)

2011-07-01

The objective of the present work was to develop, separately, methodology for production of two gaseous tracers through the sodium iodide NaI marked with {sup 123}I. Found in the nature in form different, the iodine has been used in diverse works in the area of the industry and health. These two forms of the gaseous iodine, the methyl iodide, CH{sub 3}I, and molecular iodine, I{sub 2}, are very unstable and volatile in the ambient temperature and presents different problems in clean-up and monitoring systems. The syntheses were processed with sodium iodide (NaI) 1M aqueous solution marked with 1{sup 23I}. The production of gas I{sub 2} was realized with in chlorine acid (HCl) and sodium iodate salt (NaIO{sub 3}) and the CH{sub 3}I was used, the salt of NaI and the reagent (CH{sub 3}){sub 2}SO{sub 4}. The production of gases was initially realized through in unit in glass with an inert material and the purpose was to study the kinetic of reaction and to determine the efficiency of production. The two synthesis occurs in the reaction bottle and after of produced, the gas is stored in the collect bottle that contains a starch solution for fixed the I{sub 2}, and in syntheses of CH{sub 3}I contains a silver nitrate solution for your fixation. To determine the efficiency of production of gases, analytic tests were realized, where the consumption of iodide ions of the bottle of reaction are measured. The optimization of production of the each gaseous tracer was studied varying parameter as: concentration of iodide, concentration of acid and temperature. After, the syntheses of the radiotracers were realized in the compact unit, having been used as main reagent the salt radiated of sodium iodide, Na{sup 123}I. The transportation of elementary iodine and methyl iodine was studied by a scintillation detector NaI (2 x 2)' positioned in the reaction bottle. (author)

Development of a real-time absorption method for detecting the mercaptan odorizing mixture of natural gas

NARCIS (Netherlands)

Kireev, SV; Petrov, NG; Podolyako, EM; Shnyrev, SL

The absorption of mercaptan mixtures used for odorizing natural gas and mixtures of natural gas is experimentally studied in the spectral range 2.5-20 mu m. An absorption method for the real-time detection of the odorant concentration is proposed. The method is based on intensity measurements of the

A methyl-coordinated Rh III ion in methylpentaamminerhodium(III)–chloropentaamminerhodium(III)–dithionate (0.73/2.27/3)

DEFF Research Database (Denmark)

Harris, Pernille; Kofod, Pauli

2002-01-01

Some disorder is seen in the crystal structure of [Rh(CH3)(NH3)5]0.73[RhCl(NH3)5]2.27(S2O6)3. It is, however, clear that the methyl group has a pronounced trans influence on the Rh-N distance, with an elongation of 0.11 Å. No trans influence is observed for the Rh-N distance due to the Cl- ion. B...

Dynamics for CH3F and CD3F isolated in rare gas solids

International Nuclear Information System (INIS)

Jones, L.H.; Swanson, B.I.

1982-01-01

High resolution infrared spectra have been obtained for CH 3 F and CD 3 F in argon and krypton matrices from 3 to 39 K. Low-temperature spectra show structure indicative of two stable monomer sites. As temperature is raised, the structure collapses to give symmetric peaks for each mode. The line shapes and their broadening with temperature show large dependence on the modes, isotope, and host matrix. On the basis of the absence of rovibrational structure and the very different line shapes for the various modes, we conclude that free or hindered rotation does not contribute to the absorption lines of methyl fluoride in argon or krypton matrices below 40 K. The mode dependent line broadening with increasing temperatures has been attributed to vibrational dephasing involving low energy site local phonon modes. Implications with regard to vibrational energy relaxation, which is currently thought to be dominated by a vibration to rotation energy transfer, are discussed

Global transformation of erythrocyte properties via engagement of an SH2-like sequence in band 3.

Science.gov (United States)

Puchulu-Campanella, Estela; Turrini, Francesco M; Li, Yen-Hsing; Low, Philip S

2016-11-29

Src homology 2 (SH2) domains are composed of weakly conserved sequences of ∼100 aa that bind phosphotyrosines in signaling proteins and thereby mediate intra- and intermolecular protein-protein interactions. In exploring the mechanism whereby tyrosine phosphorylation of the erythrocyte anion transporter, band 3, triggers membrane destabilization, vesiculation, and fragmentation, we discovered a SH2 signature motif positioned between membrane-spanning helices 4 and 5. Evidence that this exposed cytoplasmic sequence contributes to a functional SH2-like domain is provided by observations that: (i) it contains the most conserved sequence of SH2 domains, GSFLVR; (ii) it binds the tyrosine phosphorylated cytoplasmic domain of band 3 (cdb3-PO 4 ) with K d = 14 nM; (iii) binding of cdb3-PO 4 to erythrocyte membranes is inhibited both by antibodies against the SH2 signature sequence and dephosphorylation of cdb3-PO 4 ; (iv) label transfer experiments demonstrate the covalent transfer of photoactivatable biotin from isolated cdb3-PO 4 (but not cdb3) to band 3 in erythrocyte membranes; and (v) phosphorylation-induced binding of cdb3-PO 4 to the membrane-spanning domain of band 3 in intact cells causes global changes in membrane properties, including (i) displacement of a glycolytic enzyme complex from the membrane, (ii) inhibition of anion transport, and (iii) rupture of the band 3-ankyrin bridge connecting the spectrin-based cytoskeleton to the membrane. Because SH2-like motifs are not retrieved by normal homology searches for SH2 domains, but can be found in many tyrosine kinase-regulated transport proteins using modified search programs, we suggest that related cases of membrane transport proteins containing similar motifs are widespread in nature where they participate in regulation of cell properties.

Calibration transfer between electronic nose systems for rapid In situ measurement of pulp and paper industry emissions

Energy Technology Data Exchange (ETDEWEB)

Deshmukh, Sharvari [CSIR-National Environmental Engineering and Research Institute, Nagpur (India); Department of Instrumentation and Electronics Engineering, Jadavpur University, Kolkata (India); Kamde, Kalyani [CSIR-National Environmental Engineering and Research Institute, Nagpur (India); Jana, Arun [Center for Development of Advance Computing, Kolkata (India); Korde, Sanjivani [CSIR-National Environmental Engineering and Research Institute, Nagpur (India); Bandyopadhyay, Rajib [Department of Instrumentation and Electronics Engineering, Jadavpur University, Kolkata (India); Sankar, Ravi [Center for Development of Advance Computing, Kolkata (India); Bhattacharyya, Nabarun, E-mail: nabarun.bhattacharya@cdac.in [Center for Development of Advance Computing, Kolkata (India); Pandey, R.A., E-mail: ra_pandey@neeri.res.in [CSIR-National Environmental Engineering and Research Institute, Nagpur (India)

2014-09-02

Highlights: • E-nose developed for obnoxious emissions measurement at pulp and paper industrial site. • ANN model developed for prediction of (CH{sub 3}){sub 2}S, (CH{sub 3}){sub 2}S{sub 2}, CH{sub 3}SH and H{sub 2}S concentration. • Calibration transfer methodology developed for transfer between two e-nose instruments. • Box–Behnken design and robust regression used for calibration transfer. • Results show effective transfer of training model from one e-nose system to other. - Abstract: Electronic nose systems when deployed in network mesh can effectively provide a low budget and onsite solution for the industrial obnoxious gaseous measurement. For accurate and identical prediction capability by all the electronic nose systems, a reliable calibration transfer model needs to be implemented in order to overcome the inherent sensor array variability. In this work, robust regression (RR) is used for calibration transfer between two electronic nose systems using a Box–Behnken (BB) design. Out of the two electronic nose systems, one was trained using industrial gas samples by four artificial neural network models, for the measurement of obnoxious odours emitted from pulp and paper industries. The emissions constitute mainly of hydrogen sulphide (H{sub 2}S), methyl mercaptan (MM), dimethyl sulphide (DMS) and dimethyl disulphide (DMDS) in different proportions. A Box–Behnken design consisting of 27 experiment sets based on synthetic gas combinations of H{sub 2}S, MM, DMS and DMDS, were conducted for calibration transfer between two identical electronic nose systems. Identical sensors on both the systems were mapped and the prediction models developed using ANN were then transferred to the second system using BB–RR methodology. The results showed successful transmission of prediction models developed for one system to other system, with the mean absolute error between the actual and predicted concentration of analytes in mg L{sup −1} after calibration

Calibration transfer between electronic nose systems for rapid In situ measurement of pulp and paper industry emissions

International Nuclear Information System (INIS)

Deshmukh, Sharvari; Kamde, Kalyani; Jana, Arun; Korde, Sanjivani; Bandyopadhyay, Rajib; Sankar, Ravi; Bhattacharyya, Nabarun; Pandey, R.A.

2014-01-01

Highlights: • E-nose developed for obnoxious emissions measurement at pulp and paper industrial site. • ANN model developed for prediction of (CH 3 ) 2 S, (CH 3 ) 2 S 2 , CH 3 SH and H 2 S concentration. • Calibration transfer methodology developed for transfer between two e-nose instruments. • Box–Behnken design and robust regression used for calibration transfer. • Results show effective transfer of training model from one e-nose system to other. - Abstract: Electronic nose systems when deployed in network mesh can effectively provide a low budget and onsite solution for the industrial obnoxious gaseous measurement. For accurate and identical prediction capability by all the electronic nose systems, a reliable calibration transfer model needs to be implemented in order to overcome the inherent sensor array variability. In this work, robust regression (RR) is used for calibration transfer between two electronic nose systems using a Box–Behnken (BB) design. Out of the two electronic nose systems, one was trained using industrial gas samples by four artificial neural network models, for the measurement of obnoxious odours emitted from pulp and paper industries. The emissions constitute mainly of hydrogen sulphide (H 2 S), methyl mercaptan (MM), dimethyl sulphide (DMS) and dimethyl disulphide (DMDS) in different proportions. A Box–Behnken design consisting of 27 experiment sets based on synthetic gas combinations of H 2 S, MM, DMS and DMDS, were conducted for calibration transfer between two identical electronic nose systems. Identical sensors on both the systems were mapped and the prediction models developed using ANN were then transferred to the second system using BB–RR methodology. The results showed successful transmission of prediction models developed for one system to other system, with the mean absolute error between the actual and predicted concentration of analytes in mg L −1 after calibration transfer (on second system) being 0.076, 0

Hot filament-dissociation of (CH3)3SiH and (CH3)4Si, probed by vacuum ultra violet laser time of flight mass spectroscopy.

Science.gov (United States)

Sharma, Ramesh C; Koshi, Mitsuo

2006-11-01

The decomposition of trimethylsilane and tetramethylsilane has been investigated for the first time, using hot wire (catalytic) at various temperatures. Trimethylsilane is catalytic-dissociated in these species SiH(2), CH(3)SiH, CH(3), CH(2)Si. Time of flight mass spectroscopy signal of these species are linearly increasing with increasing catalytic-temperature. Time of flight mass spectroscopy (TOFMS) signals of (CH(3))(3)SiH and photodissociated into (CH(3))(2)SiH are decreasing with increasing hot filament temperature. TOFMS signal of (CH(3))(4)Si is decreasing with increasing hot wire temperature, but (CH(3))(3)Si signal is almost constant with increasing the temperature. We calculated activation energies of dissociated species of the parental molecules for fundamental information of reaction kinetics for the first time. Catalytic-dissociation of trimethylsilane, and tetramethylsilane single source time of flight coupled single photon VUV (118 nm) photoionization collisionless radicals at temperature range of tungsten filament 800-2360 K. The study is focused to understand the fundamental information on reaction kinetics of these molecules at hot wire temperature, and processes of catalytic-chemical vapour deposition (Cat-CVD) technique which could be implemented in amorphous and crystalline SiC semiconductors thin films.

Photodissociation dynamics of the simplest alkyl peroxy radicals, CH3OO and C2H5OO, at 248 nm

Science.gov (United States)

Sullivan, Erin N.; Nichols, Bethan; Neumark, Daniel M.

2018-01-01

The photodissociation dynamics of the simplest alkyl peroxy radicals, methyl peroxy (CH3OO) and ethyl peroxy (C2H5OO), are investigated using fast beam photofragment translational spectroscopy. A fast beam of CH3OO- or C2H5OO- anions is photodetached to generate neutral radicals that are subsequently dissociated using 248 nm photons. The coincident detection of the photofragment positions and arrival times allows for the determination of mass, translational energy, and angular distributions for both two-body and three-body dissociation events. CH3OO exhibits repulsive O loss resulting in the formation of O(1D) + CH3O with high translational energy release. Minor two-body channels leading to OH + CH2O and CH3O + O(3P) formation are also detected. In addition, small amounts of H + O(3P) + CH2O are observed and attributed to O loss followed by CH3O dissociation. C2H5OO exhibits more complex dissociation dynamics, in which O loss and OH loss occur in roughly equivalent amounts with O(1D) formed as the dominant O atom electronic state via dissociation on a repulsive surface. Minor two-body channels leading to the formation of O2 + C2H5 and HO2 + C2H4 are also observed and attributed to a ground state dissociation pathway following internal conversion. Additionally, C2H5OO dissociation yields a three-body product channel, CH3 + O(3P) + CH2O, for which the proposed mechanism is repulsive O loss followed by the dissociation of C2H5O over a barrier. These results are compared to a recent study of tert-butyl peroxy (t-BuOO) in which 248 nm excitation results in three-body dissociation and ground state two-body dissociation but no O(1D) production.

Kinetics of the CH3 + HCl/DCl → CH4/CH3D + Cl and CD3 + HCl/DCl → CD3H/CD4 + Cl reactions: An experimental H atom tunneling investigation

International Nuclear Information System (INIS)

Eskola, Arkke J.; Seetula, Jorma A.; Timonen, Raimo S.

2006-01-01

The kinetics of the radical reactions of CH 3 with HCl or DCl and CD 3 with HCl or DCl have been investigated in a temperature controlled tubular reactor coupled to a photoionization mass spectrometer. The CH 3 (or CD 3 ) radical, R, was produced homogeneously in the reactor by a pulsed 193 nm exciplex laser photolysis of CH 3 COCH 3 (or CD 3 COCD 3 ). The decay of CH 3 /CD 3 was monitored as a function of HCl/DCl concentration under pseudo-first-order conditions to determine the rate constants as a function of temperature, typically from 188 to 500 K. The rate constants of the CH 3 and CD 3 reactions with HCl had strong non-Arrhenius behavior at low temperatures. The rate constants were fitted to a modified Arrhenius expression k = QA exp (-E a /RT) (error limits stated are 1σ + Students t values, units in cm 3 molecule -1 s -1 ): k(CH 3 + HCl) = [1.004 + 85.64 exp (-0.02438 x T/K)] x (3.3 ± 1.3) x 10 -13 exp [-(4.8 ± 0.6) kJ mol -1 /RT] and k(CD 3 + HCl) = [1.002 + 73.31 exp (-0.02505 x T/K)] x (2.7 ± 1.2) x 10 -13 exp [-(3.5 ± 0.5) kJ mol -1 /RT]. The radical reactions with DCl were studied separately over a wide ranges of temperatures and in these temperature ranges the rate constants determined were fitted to a conventional Arrhenius expression k = A exp (-E a /RT) (error limits stated are 1σ + Students t values, units in cm 3 molecule -1 s -1 ): k(CH 3 + DCl) = (2.4 ± 1.6) x 10 -13 exp [-(7.8 ± 1.4) kJ mol -1 /RT] and k(CD 3 + DCl) = (1.2 ± 0.4) x 10 -13 exp [-(5.2 ± 0.2) kJ mol -1 /RT] cm 3 molecule -1 s -1 . Curvature in the Arrhenius plots of the H-atom abstraction reactions at low temperatures was analyzed by considering H-atom tunneling through the reaction barrier and primary kinetic isotope effect. Contribution of tunneling in it was concluded to be negligible. In addition, secondary isotope effect was measured

Arabidopsis SH3P2 is an ubiquitin-binding protein that functions together with ESCRT-I and the deubiquitylating enzyme AMSH3.

Science.gov (United States)

Nagel, Marie-Kristin; Kalinowska, Kamila; Vogel, Karin; Reynolds, Gregory D; Wu, Zhixiang; Anzenberger, Franziska; Ichikawa, Mie; Tsutsumi, Chie; Sato, Masa H; Kuster, Bernhard; Bednarek, Sebastian Y; Isono, Erika

2017-08-22

Clathrin-mediated endocytosis of plasma membrane proteins is an essential regulatory process that controls plasma membrane protein abundance and is therefore important for many signaling pathways, such as hormone signaling and biotic and abiotic stress responses. On endosomal sorting, plasma membrane proteins maybe recycled or targeted for vacuolar degradation, which is dependent on ubiquitin modification of the cargos and is driven by the endosomal sorting complexes required for transport (ESCRTs). Components of the ESCRT machinery are highly conserved among eukaryotes, but homologs of ESCRT-0 that are responsible for recognition and concentration of ubiquitylated proteins are absent in plants. Recently several ubiquitin-binding proteins have been identified that serve in place of ESCRT-0; however, their function in ubiquitin recognition and endosomal trafficking is not well understood yet. In this study, we identified Src homology-3 (SH3) domain-containing protein 2 (SH3P2) as a ubiquitin- and ESCRT-I-binding protein that functions in intracellular trafficking. SH3P2 colocalized with clathrin light chain-labeled punctate structures and interacted with clathrin heavy chain in planta , indicating a role for SH3P2 in clathrin-mediated endocytosis. Furthermore, SH3P2 cofractionates with clathrin-coated vesicles (CCVs), suggesting that it associates with CCVs in planta Mutants of SH3P2 and VPS23 genetically interact, suggesting that they could function in the same pathway. Based on these results, we suggest a role of SH3P2 as an ubiquitin-binding protein that binds and transfers ubiquitylated proteins to the ESCRT machinery.

Structural and Kinetic Evidence for an Extended Hydrogen-Bonding Network in Catalysis of Methyl Group Transfer

International Nuclear Information System (INIS)

Doukov, T.; Hemmi, H.; Drennan, C.; Ragsdale, S.

2007-01-01

The methyltetrahydrofolate (CH 3 -H 4 folate) corrinoid-ironsulfur protein (CFeSP) methyltransferase (MeTr) catalyzes transfer of the methyl group of CH3-H4folate to cob(I)amide. This key step in anaerobic CO and CO 2 fixation is similar to the first half-reaction in the mechanisms of other cobalamin-dependent methyltransferases. Methyl transfer requires electrophilic activation of the methyl group of CH 3 -H 4 folate, which includes proton transfer to the N5 group of the pterin ring and poises the methyl group for reaction with the Co(I) nucleophile. The structure of the binary CH 3 -H 4 folate/MeTr complex (revealed here) lacks any obvious proton donor near the N5 group. Instead, an Asn residue and water molecules are found within H-bonding distance of N5. Structural and kinetic experiments described here are consistent with the involvement of an extended H-bonding network in proton transfer to N5 of the folate that includes an Asn (Asn-199 in MeTr), a conserved Asp (Asp-160), and a water molecule. This situation is reminiscent of purine nucleoside phosphorylase, which involves protonation of the purine N7 in the transition state and is accomplished by an extended H-bond network that includes water molecules, a Glu residue, and an Asn residue (Kicska, G. A., Tyler, P. C., Evans, G. B., Furneaux, R. H., Shi, W., Fedorov, A., Lewandowicz, A., Cahill, S. M., Almo, S. C., and Schramm, V. L. (2002) Biochemistry 41, 14489-14498). In MeTr, the Asn residue swings from a distant position to within H-bonding distance of the N5 atom upon CH 3 -H 4 folate binding. An N199A variant exhibits only ∼20-fold weakened affinity for CH 3 -H 4 folate but a much more marked 20,000-40,000-fold effect on catalysis, suggesting that Asn-199 plays an important role in stabilizing a transition state or high energy intermediate for methyl transfer

Introducing ionic and/or hydrogen bonds into the SAM//Ga2O3 top-interface of Ag(TS)/S(CH2)nT//Ga2O3/EGaIn junctions.

Science.gov (United States)

Bowers, Carleen M; Liao, Kung-Ching; Yoon, Hyo Jae; Rappoport, Dmitrij; Baghbanzadeh, Mostafa; Simeone, Felice C; Whitesides, George M

2014-06-11

Junctions with the structure Ag(TS)/S(CH2)nT//Ga2O3/EGaIn (where S(CH2)nT is a self-assembled monolayer, SAM, of n-alkanethiolate bearing a terminal functional group T) make it possible to examine the response of rates of charge transport by tunneling to changes in the strength of the interaction between T and Ga2O3. Introducing a series of Lewis acidic/basic functional groups (T = -OH, -SH, -CO2H, -CONH2, and -PO3H) at the terminus of the SAM gave values for the tunneling current density, J(V) in A/cm(2), that were indistinguishable (i.e., differed by less than a factor of 3) from the values observed with n-alkanethiolates of equivalent length. The insensitivity of the rate of tunneling to changes in the terminal functional group implies that replacing weak van der Waals contact interactions with stronger hydrogen- or ionic bonds at the T//Ga2O3 interface does not change the shape (i.e., the height or width) of the tunneling barrier enough to affect rates of charge transport. A comparison of the injection current, J0, for T = -CO2H, and T = -CH2CH3--two groups having similar extended lengths (in Å, or in numbers of non-hydrogen atoms)--suggests that both groups make indistinguishable contributions to the height of the tunneling barrier.

CH3NH3Pb1-xMgxI3 perovskites as environmentally friendly photovoltaic materials

Science.gov (United States)

Zhang, Y. D.; Feng, J.

2018-01-01

In an effort to reduce the toxicity of Pb in perovskite solar cells, the band structures, electron and hole effective masses, and electronic and optical properties of the novel perovskites CH3NH3Pb1-xMgxI3 were predicted using density functional theory with the scalar relativistic generalized gradient approximation. The calculation results indicated that the introduction of the Mg component caused the band gaps of the CH3NH3Pb1-xMgxI3 compounds to exceed that of CH3NH3PbI3. The calculated absorption coefficients of the CH3NH3PbI3 and CH3NH3Pb1-xMgxI3 perovskites revealed that substituting 12.5 mol % of the Pb in CH3NH3PbI3 with Mg had little effect on the absorption ability. Surprisingly, it was also found that CH3NH3Pb0.75Mg0.25I3 retained up to 83% of the absorption performance relative to CH3NH3PbI3. This indicates that the amount of toxic Pb used in perovskite solar cells could be reduced by a quarter while retaining over 80% of the light-absorbing ability. In general, these novel CH3NH3Pb1-xMgxI3 (x ≤ 0.25) perovskites represent promising candidates for environmentally friendly light-harvesting materials for use in solar cells.

The SH2 and SH3 domains of mammalian Grb2 couple the EGF receptor to the Ras activator mSos1.

Science.gov (United States)

Rozakis-Adcock, M; Fernley, R; Wade, J; Pawson, T; Bowtell, D

1993-05-06

Many tyrosine kinases, including the receptors for hormones such as epidermal growth factor (EGF), nerve growth factor and insulin, transmit intracellular signals through Ras proteins. Ligand binding to such receptors stimulates Ras guanine-nucleotide-exchange activity and increases the level of GTP-bound Ras, suggesting that these tyrosine kinases may activate a guanine-nucleotide releasing protein (GNRP). In Caenorhabditis elegans and Drosophila, genetic studies have shown that Ras activation by tyrosine kinases requires the protein Sem-5/drk, which contains a single Src-homology (SH) 2 domain and two flanking SH3 domains. Sem-5 is homologous to the mammalian protein Grb2, which binds the autophosphorylated EGF receptor and other phosphotyrosine-containing proteins such as Shc through its SH2 domain. Here we show that in rodent fibroblasts, the SH3 domains of Grb2 are bound to the proline-rich carboxy-terminal tail of mSos1, a protein homologous to Drosophila Sos. Sos is required for Ras signalling and contains a central domain related to known Ras-GNRPs. EGF stimulation induces binding of the Grb2-mSos1 complex to the autophosphorylated EGF receptor, and mSos1 phosphorylation. Grb2 therefore appears to link tyrosine kinases to a Ras-GNRP in mammalian cells.

Optical monitoring of CH3NH3PbI3 thin films upon atmospheric exposure

International Nuclear Information System (INIS)

Ghimire, Kiran; Zhao, Dewei; Cimaroli, Alex; Ke, Weijun; Yan, Yanfa; Podraza, Nikolas J

2016-01-01

CH 3 NH 3 PbI 3 perovskite films of interest for photovoltaic (PV) devices have been prepared by (i) vapor deposition and (ii) solution processing. Complex dielectric function ( ε   =   ε 1   +  i ε 2 ) spectra and structural parameters of the films have been extracted using near infrared to ultraviolet spectroscopic ellipsometry. In situ real time spectroscopic ellipsometry (RTSE) over a 48 h period has been performed on vapor deposited CH 3 NH 3 PbI 3 after the deposition in normal atmospheric laboratory ambient conditions. Analysis of RTSE data for vapor deposited CH 3 NH 3 PbI 3 film prepared under un-optimized conditions identifies phase segregated PbI 2 and CH 3 NH 3 I at the substrate/film interface and unreacted PbI 2 and CH 3 NH 3 I on the film surface. This analysis also provides the time dependence of the effective thicknesses of perovskite film, unreacted components, and phase segregated layers to track CH 3 NH 3 PbI 3 decomposition. (paper)

Methanesulfonates of high-valent metals. Syntheses and structural features of MoO{sub 2}(CH{sub 3}SO{sub 3}){sub 2}, UO{sub 2}(CH{sub 3}SO{sub 3}){sub 2}, ReO{sub 3}(CH{sub 3}SO{sub 3}), VO(CH{sub 3}SO{sub 3}){sub 2}, and V{sub 2}O{sub 3}(CH{sub 3}SO{sub 3}){sub 4} and their thermal decomposition under N{sub 2} and O{sub 2} atmosphere

Energy Technology Data Exchange (ETDEWEB)

Betke, Ulf; Neuschulz, Kai; Wickleder, Mathias S. [Carl von Ossietzky University of Oldenburg, Institute of Pure and Applied Chemistry (Germany)

2011-11-04

Oxide methanesulfonates of Mo, U, Re, and V have been prepared by reaction of MoO{sub 3}, UO{sub 2}(CH{sub 3}COO){sub 2}.2 H{sub 2}O, Re{sub 2}O{sub 7}(H{sub 2}O){sub 2}, and V{sub 2}O{sub 5} with CH{sub 3}SO{sub 3}H or mixtures thereof with its anhydride. These compounds are the first examples of solvent-free oxide methanesulfonates of these elements. MoO{sub 2}(CH{sub 3}SO{sub 3}){sub 2} (Pbca, a=1487.05(4), b=752.55(2), c=1549.61(5) pm, V=1.73414(9) nm{sup 3}, Z=8) contains [MoO{sub 2}] moieties connected by [CH{sub 3}SO{sub 3}] ions to form layers parallel to (100). UO{sub 2}(CH{sub 3}SO{sub 3}){sub 2} (P2{sub 1}/c, a=1320.4(1), b=1014.41(6), c=1533.7(1) pm, β=112.80(1) {sup circle}, V=1.8937(3) nm{sup 3}, Z=8) consists of linear UO{sub 2}{sup 2+} ions coordinated by five [CH{sub 3}SO{sub 3}] ions, forming a layer structure. VO(CH{sub 3}SO{sub 3}){sub 2} (P2{sub 1}/c, a=1136.5(1), b=869.87(7), c=915.5(1) pm, β=113.66(1) {sup circle}, V=0.8290(2) nm{sup 3}, Z=4) contains [VO] units connected by methanesulfonate anions to form corrugated layers parallel to (100). In ReO{sub 3}(CH{sub 3}SO{sub 3}) (P anti 1, a=574.0(1), b=1279.6(3), c=1641.9(3) pm, α=102.08(2), β=96.11(2), γ=99.04(2) {sup circle}, V=1.1523(4) nm{sup 3}, Z=8) a chain structure exhibiting infinite O-[ReO{sub 2}]-O-[ReO{sub 2}]-O chains is formed. Each [ReO{sub 2}]-O-[ReO{sub 2}] unit is coordinated by two bidentate [CH{sub 3}SO{sub 3}] ions. V{sub 2}O{sub 3}(CH{sub 3}SO{sub 3}){sub 4} (I2/a, a=1645.2(3), b=583.1(1), c=1670.2(3) pm, β=102.58(3), V=1.5637(5) pm{sup 3}, Z=4) adopts a chain structure, too, but contains discrete [VO]-O-[VO] moieties, each coordinated by two bidentate [CH{sub 3}SO{sub 3}] ligands. Additional methanesulfonate ions connect the [V{sub 2}O{sub 3}] groups along [001]. Thermal decomposition of the compounds was monitored under N{sub 2} and O{sub 2} atmosphere by thermogravimetric/differential thermal analysis and XRD measurements. Under N{sub 2} the decomposition proceeds

Identification of SH2B2β as an Inhibitor for SH2B1- and SH2B2α-Promoted Janus Kinase-2 Activation and Insulin Signaling

OpenAIRE

Li, Minghua; Li, Zhiqin; Morris, David L.; Rui, Liangyou

2007-01-01

The SH2B family has three members (SH2B1, SH2B2, and SH2B3) that contain conserved dimerization (DD), pleckstrin homology, and SH2 domains. The DD domain mediates the formation of homo- and heterodimers between members of the SH2B family. The SH2 domain of SH2B1 (previously named SH2-B) or SH2B2 (previously named APS) binds to phosphorylated tyrosines in a variety of tyrosine kinases, including Janus kinase-2 (JAK2) and the insulin receptor, thereby promoting the activation of JAK2 or the ins...

Photovoltaic properties of Cu-doped CH3NH3PbI3 with perovskite structure

Science.gov (United States)

Shirahata, Yasuhiro; Oku, Takeo

2017-01-01

Photovoltaic properties of copper (Cu)-doped perovskite (CH3NH3PbCuxI3+x) photovoltaic devices with different Cu content were investigated. The CH3NH3PbCuxI3+x films were polycrystalline with a tetragonal system, and their lattice constants and crystallite size varied with Cu doping. Compared to conversion efficiencies of non-doped CH3NH3PbI3 photovoltaic device, those of CH3NH3PbCuxI3+x photovoltaic devises increased. The improvement of photovoltaic properties was attributed to partial substitution of Cu at the Pb sites.

Atmospheric chemistry of 4 : 2 fluorotelomer alcohol (CF3(CF2)(3)CH2CH2OH): Products and mechanism of Cl atom initiated oxidation

DEFF Research Database (Denmark)

Hurley, MD; Ball, JC; Wallington, TJ

2004-01-01

Smog chamber/FTIR techniques were used to study the products and mechanism of the Cl atom initiated oxidation of 4:2 fluorotelomer alcohol (CF3(CF2)(3)CH2CH2OH) in 700 Torr of N-2/O-2 diluent at 296 K. CF3(CF2)(3)CH2CHO is the sole primary oxidation product. CF3(CF2)(3)CHO, CF3(CF2)(3)CH2COOH...... respectively. Using relative rate techniques, a value of k(Cl + CF3(CF2)(3)CH2CHO) = (1.84 +/- 0.30) x 10(-11) cm(3) molecule(-1) s(-1) was determined. The yield of the perfluorinated acid, CF3(CF2)(3)COOH, from the 4:2 fluorotelomer alcohol increased with the diluent gas oxygen concentration......, and CF3(CF2)(3)CH2C(O)OOH are secondary oxidation products. Further irradiation results in the formation of CF3(CF2)(3)COOH, COF2, and CF3OH. CF3(CF2)(3)CHO, CF3(CF2)(3)CH2COOH, and CF3(CF2)(3)CH2C(O)OOH are formed from CF3(CF2)(3)CH2CHO oxidation in yields of 46 27 and less than or equal to 27...

THE PECULIAR DISTRIBUTION OF CH{sub 3}CN IN IRC +10216 SEEN BY ALMA

Energy Technology Data Exchange (ETDEWEB)

Agúndez, M.; Cernicharo, J.; Quintana-Lacaci, G.; Prieto, L. Velilla [Instituto de Ciencia de Materiales de Madrid, CSIC, C/Sor Juana Inés de la Cruz 3, E-28049 Cantoblanco (Spain); Castro-Carrizo, A.; Guélin, M. [Institut de Radioastronomie Millimétrique, 300 rue de la Piscine, F-38406 St. Martin d’Héres (France); Marcelino, N. [INAF, Istituto di Radioastronomia, via Gobetti 101, I-40129 Bologna (Italy)

2015-12-01

IRC +10216 is a circumstellar envelope around a carbon-rich evolved star which contains a large variety of molecules. According to interferometric observations, molecules are distributed either concentrated around the central star or as a hollow shell with a radius of ∼15″. We present ALMA Cycle 0 band 6 observations of the J = 14 – 13 rotational transition of CH{sub 3}CN in IRC +10216, obtained with an angular resolution of 0.″76 × 0.″61. The bulk of the emission is distributed as a hollow shell located at just ∼2″ from the star, with a void of emission in the central region up to a radius of ∼1″. This spatial distribution is markedly different from those found to date in this source for other molecules. Our analysis indicates that methyl cyanide is not formed in either the stellar photosphere or far in the outer envelope, but at radial distances as short as 1″–2″, reaching a maximum abundance of ∼0.02 molecules cm{sup −3} at 2″ from the star. Standard chemical models of IRC +10216 predict that the bulk of CH{sub 3}CN molecules should be present at a radius of ∼15″ where other species such as polyyne radicals and cyanopolyynes are observed, with an additional inner component within 1″ from the star. The non-uniform structure of the circumstellar envelope and grain surface processes are discussed as possible causes of the peculiar distribution of methyl cyanide in IRC +10216.

On the growth of CH3NH3PbI3-xClx single crystal and characterization

Science.gov (United States)

Su, J.; Wang, W. F.; Lei, Y.; Zhang, L.; Xu, L. H.; Wang, D.; Lu, D.; Bai, Y.

2018-05-01

In this paper, CH3NH3PbI3-xClx crystal was grown by solution cooling method with CH3NH3I and PbCl2 as raw materials. Lead compounds and CH3NH3PbI3-xClx crystal with size about 6 mm × 4 mm × 2 mm were obtained. The chemical reactions with different CH3NH3I/PbCl2 ratios were analyzed. XPS shows the content of chlorine in CH3NH3PbI3-xClx is about 0.91%. PXRD, FT-IR, Raman and absorbance spectra were used to study the structure and optical properties of CH3NH3PbI3-xClx by comparing with CH3NH3PbI3 crystal. The CH3NH3PbI3-xClx crystal grown is of tetragonal structure with the lattice constants a = b = 8.8165 Å, c = 12.7920 Å and the bandgap value of 1.57 eV.

The role of SH3BP2 in the pathophysiology of cherubism

Directory of Open Access Journals (Sweden)

Reichenberger Ernst J

2012-05-01

Full Text Available Abstract Cherubism is a rare bone dysplasia that is characterized by symmetrical bone resorption limited to the jaws. Bone lesions are filled with soft fibrous giant cell-rich tissue that can expand and cause severe facial deformity. The disorder typically begins in children at ages of 2-5 years and the bone resorption and facial swelling continues until puberty; in most cases the lesions regress spontaneously thereafter. Most patients with cherubism have germline mutations in the gene encoding SH3BP2, an adapter protein involved in adaptive and innate immune response signaling. A mouse model carrying a Pro416Arg mutation in SH3BP2 develops osteopenia and expansile lytic lesions in bone and some soft tissue organs. In this review we discuss the genetics of cherubism, the biological functions of SH3BP2 and the analysis of the mouse model. The data suggest that the underlying cause for cherubism is a systemic autoinflammatory response to physiologic challenges despite the localized appearance of bone resorption and fibrous expansion to the jaws in humans.

The surface chemistry of nanocrystalline MgO catalysts for FAME production: An in situ XPS study of H2O, CH3OH and CH3OAc adsorption

Science.gov (United States)

Montero, J. M.; Isaacs, M. A.; Lee, A. F.; Lynam, J. M.; Wilson, K.

2016-04-01

An in situ XPS study of water, methanol and methyl acetate adsorption over as-synthesised and calcined MgO nanocatalysts is reported with a view to gaining insight into the surface adsorption of key components relevant to fatty acid methyl esters (biodiesel) production during the transesterification of triglycerides with methanol. High temperature calcined NanoMgO-700 adsorbed all three species more readily than the parent material due to the higher density of electron-rich (111) and (110) facets exposed over the larger crystallites. Water and methanol chemisorb over the NanoMgO-700 through the conversion of surface O2 - sites to OH- and coincident creation of Mg-OH or Mg-OCH3 moieties respectively. A model is proposed in which the dissociative chemisorption of methanol occurs preferentially over defect and edge sites of NanoMgO-700, with higher methanol coverages resulting in physisorption over weakly basic (100) facets. Methyl acetate undergoes more complex surface chemistry over NanoMgO-700, with C-H dissociation and ester cleavage forming surface hydroxyl and acetate species even at extremely low coverages, indicative of preferential adsorption at defects. Comparison of C 1s spectra with spent catalysts from tributyrin transesterification suggest that ester hydrolysis plays a key factor in the deactivation of MgO catalysts for biodiesel production.

Characterization of a novel weak interaction between MUC1 and Src-SH3 using nuclear magnetic resonance spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Gunasekara, Nirosha [Department of Laboratory Medicine and Pathology, University of Alberta, 5B4.21 WCM Health Science Centre, 8440-112th Street, Edmonton, Alberta, Canada T6G 2R7 (Canada); Sykes, Brian, E-mail: brian.sykes@ualberta.ca [Department of Biochemistry, 4-19B Medical Sciences Bldg., University of Alberta Edmonton, Alberta, Canada T6G 2H7 (Canada); Hugh, Judith, E-mail: judithh@ualberta.ca [Department of Laboratory Medicine and Pathology, University of Alberta, 5B4.21 WCM Health Science Centre, 8440-112th Street, Edmonton, Alberta, Canada T6G 2R7 (Canada)

2012-05-18

Highlights: Black-Right-Pointing-Pointer MUC1 binds the Src-SH3 domain potentially triggering Src dependent cell migration. Black-Right-Pointing-Pointer NMR Spectroscopy was used to monitor MUC1-CD and Src SH3 domain titrations. Black-Right-Pointing-Pointer MUC1-CD peptides bind with a low affinity (K{sub d} of 2-3 mM) to a non-canonical site. Black-Right-Pointing-Pointer Weak interactions may mediate dynamic processes like migration. Black-Right-Pointing-Pointer The MUC1-CD and Src-SH3 interaction may be a prime target to inhibit cell migration. -- Abstract: Breast cancer causes death through cancer cell migration and subsequent metastasis to distant organs. In vitro, the MUC1 mucin can mediate breast cancer cell migration by binding to intercellular adhesion molecule-1 (ICAM-1). This migration is dependent on MUC1 cytoplasmic domain (MUC1-CD) activation of the non-receptor tyrosine kinase, Src, possibly through competitive displacement of an inhibitory Src intramolecular SH3 binding. Therefore, we characterized the binding site and affinity of the MUC1-CD for Src-SH3 using multidimensional nuclear magnetic resonance (NMR) spectroscopy to monitor the titration of the {sup 15}N labeled Src-SH3 domain with synthetic native and mutant peptides of MUC1-CD. The results revealed that the dissociation constant (K{sub d}) for the interaction of the native MUC1-CD peptides and Src-SH3 domain was weak with a K{sub d} of 2-3 mM. Notably, the SH3 residues most perturbed upon peptide binding were located outside the usual hydrophobic binding cleft in a previously described alternate binding site on the Src-SH3, suggesting that MUC1-CD binds to a non-canonical site. The binding characteristics outlined here suggest that the interaction between Src-SH3 and MUC1-CD represents a novel weak electrostatic interaction of the type which is increasingly recognized as important in transient and dynamic protein complexes required for cell migration and signal transduction. As such, this

Beta-Phosphinoethylboranes as Ambiphilic Ligands in Nickel-Methyl Complexes

Energy Technology Data Exchange (ETDEWEB)

Fischbach, Andreas; Bazinet, Patrick R.; Waterman, Rory; Tilley, T. Don

2007-10-28

The ambiphilic {beta}-phosphinoethylboranes Ph{sub 2}PCH{sub 2}CH{sub 2}BR{sub 2} (BR{sub 2} = BCy{sub 2} (1a), BBN (1b)), which feature a ethano spacer CH{sub 2}CH{sub 2} between the Lewis acidic boryl and Lewis basic phosphino groups, were synthesized in nearly quantitative yields via the hydroboration of vinyldiphenylphosphine. Compounds 1a and 1b were fully characterized by elemental analysis, and by NMR and IR spectroscopy. X-ray crystallographic studies of compound 1b revealed infinite helical chains of the molecules connected through P{hor_ellipsis}B donor-acceptor interactions. The ability of these ambiphilic ligands to concurrently act as donors and acceptors was highlighted by their reactions with (dmpe)NiMe{sub 2}. Zwitterionic complexes (dmpe)NiMe(Ph{sub 2}PCH{sub 2}CH{sub 2}BCy{sub 2}Me) (2a) and (dmpe)NiMe(Ph{sub 2}PCH{sub 2}CH{sub 2}[BBN]Me) (2b) were generated via the abstraction of one of the methyl groups, forming a borate, and intramolecular coordination of the phosphine moiety to the resulting cationic metal center. Compound 2b was characterized by X-ray crystallography. Furthermore, B(C{sub 6}F{sub 5}){sub 3} abstracts the methyl group of a coordinated borate ligand to generate a free, 3-coordinate borane center in [(dmpe)NiMe(1a)]{sup +}[MeB(C{sub 6}F{sub 5}){sub 3}]{sup -} (3).

Non-Covalent Interactions in Hydrogen Storage Materials LiN(CH32BH3 and KN(CH32BH3

Directory of Open Access Journals (Sweden)

Filip Sagan

2016-03-01

Full Text Available In the present work, an in-depth, qualitative and quantitative description of non-covalent interactions in the hydrogen storage materials LiN(CH32BH3 and KN(CH32BH3 was performed by means of the charge and energy decomposition method (ETS-NOCV as well as the Interacting Quantum Atoms (IQA approach. It was determined that both crystals are stabilized by electrostatically dominated intra- and intermolecular M∙∙∙H–B interactions (M = Li, K. For LiN(CH32BH3 the intramolecular charge transfer appeared (B–H→Li to be more pronounced compared with the corresponding intermolecular contribution. We clarified for the first time, based on the ETS-NOCV and IQA methods, that homopolar BH∙∙∙HB interactions in LiN(CH32BH3 can be considered as destabilizing (due to the dominance of repulsion caused by negatively charged borane units, despite the fact that some charge delocalization within BH∙∙∙HB contacts is enforced (which explains H∙∙∙H bond critical points found from the QTAIM method. Interestingly, quite similar (to BH∙∙∙HB intermolecular homopolar dihydrogen bonds CH∙∙∙HC appared to significantly stabilize both crystals—the ETS-NOCV scheme allowed us to conclude that CH∙∙∙HC interactions are dispersion dominated, however, the electrostatic and σ/σ*(C–H charge transfer contributions are also important. These interactions appeared to be more pronounced in KN(CH32BH3 compared with LiN(CH32BH3.

Gamma-ray radiolysis of methyl iodide in air, in presence of water vapor

International Nuclear Information System (INIS)

Aubert, F.

2002-03-01

This work aims at modelling the processes involved in gamma-radiolysis of methyl iodide diluted in air in presence of steam. It is to determine quantitative and qualitative information, to quantify the importance of the organic iodides destruction in case of a nuclear reactor accident. The main data for radiochemistry and iodine compounds (I x O y and INO x ) formation were reviewed and analysed. Literature data about air products radiolysis reactivity towards I 2 and CH 3 I were used to develop a mechanistic model for methyl iodide destruction in the gas phase under gamma irradiation. An ab initio study was realised for a better understanding of atomic nitrogen ( 4 S and 2 D) reactivity towards CH 3 I. The model was tested on the available experimental data and constitute a way to investigate the main processus involved in methyl iodide destruction. For the low CH 3 I concentrations, about 10 -7 - 10 -8 mol.dm -3 , N and e - are mainly responsible for the destruction. I 2 O 4 (highest iodine oxide in the model) and IONO 2 are the main resulting iodinated' compounds. (author)

CH3NH3PbI3 based solar cell: Modified by antisolvent treatment

Science.gov (United States)

Nandi, Pronoy; Giri, Chandan; Bansode, Umesh; Topwal, D.

2017-05-01

Solar cells based on new class of organic inorganic hybrid perovskite CH3NH3PbI3 were prepared by Ethyl acetate (EA); antisolvent treatment for the first time. This treatment results in new morphology for CH3NH3PbI3 thin film. FESEM image shows microrod type structures of CH3NH3PbI3 after EA antisolvent treatment. Energy band diagram was constructed using photoluminescence and photoemission studies. A better power conversion efficiency was achieved in EA treated film compare to without EA treated film.

Effects of Boreal Lake Wetlands on Atmospheric 13CH3D and 12CH2D2

Science.gov (United States)

Haghnegahdar, M. A.; Kohl, I. E.; Schauble, E. A.; Walter Anthony, K. M.; Young, E. D.

2017-12-01

Recently, we developed a theoretical model to investigate the potential use of 13CH3D and 12CH2D2 as tools for tracking atmospheric methane budget. We used electronic structure methods to estimate kinetic isotope fractionations associated with the major sink reactions of CH4 in air (reactions with •OH and Cl•), and literature data with reconnaissance measurements of the relative abundances of 13CH3D and 12CH2D2 to estimate the compositions of the largest atmospheric sources. Here we present new methane rare isotopologue data from boreal wetlands, comprising one of the most important sources, in order to evaluate the robustness of the model. Boreal wetlands (>55° N) account for more than half of the wetland area in the Northern hemisphere. We analyzed methane samples from high latitude lakes representing different geographical regions, geological and ecological contexts, methane fluxes, and isotopic signatures. Using clumped isotopes of CH4 we are able to determine the likely production mechanism for natural CH4 samples. So far, all of our analyzed samples except one plot in the microbial pure-culture methanogenesis field (Young et al. 2017) with ranges of -0.2‰ to +1.2‰ for Δ13CH3D, and -29.6‰ to -18.2‰ for Δ12CH2D2. These compositions are far from equilibrium. The one exception, from Lake Doughnut, Alaska, exhibits Δ13CH3D and Δ12CH2D2 values of +5.2‰ and +18.7‰, respectively, which fall near ambient thermodynamic equilibrium values. This may be an effect of methanotrophy. Mean Δ13CH3D and Δ12CH2D2 for all lake samples are +1.7‰ and -15.4‰ respectively, compared to our original estimate of +6.1‰ and +21.2‰ for the wetland methane source based on an assumption of equilibrium. If we assume that these samples are representative of the overall wetland source, Δ13CH3D decreases by 0.8‰ and Δ12CH2D2 decreases by 0.6‰ in our model of bulk atmospheric methane. Δ13CH3D and Δ12CH2D2 values of air (including •OH and Cl• sink

Association between receptor protein-tyrosine phosphatase RPTPalpha and the Grb2 adaptor. Dual Src homology (SH) 2/SH3 domain requirement and functional consequences

DEFF Research Database (Denmark)

Su, J; Yang, L T; Sap, J

1996-01-01

domain in Grb2 (, ). We show here that association of Grb2 with RPTPalpha also involves a critical function for the C-terminal SH3 domain of Grb2. Furthermore, Grb2 SH3 binding peptides interfere with RPTPalpha-Grb2 association in vitro, and the RPTPalpha protein can dissociate the Grb2-Sos complex...... in vivo. These observations constitute a novel mode of Grb2 association and suggest a model in which association with a tyrosine-phosphorylated protein restricts the repertoire of SH3 binding proteins with which Grb2 can simultaneously interact. The function of the Tyr798 tyrosine phosphorylation/Grb2...... binding site in RPTPalpha was studied further by expression of wild type or mutant RPTPalpha proteins in PC12 cells. In these cells, wild type RPTPalpha interferes with acidic fibroblast growth factor-induced neurite outgrowth; this effect requires both the catalytic activity and the Grb2 binding Tyr798...

Solvated copper(I) hexafluorosilicate π-complexes based on [Cu2(amtd)2]2+ (amtd = 2-allylamino-5-methyl-1,3,4-thiadiazole) dimer

OpenAIRE

Goreshnik, E.A.; Veryasov, G.; Morozov, Dmitry; Slyvka, Yu.; Ardan, B.; Mys'kiv, M.G.

2016-01-01

[Cu2(amdt)2]SiF6·C6H6 and [Cu2(amdt)2(H2O)2]SiF6·CH3CN·2H2O (amdt = 2-allylamino-5- methyl-1,3,4-thiadiazole) were obtained by alternating-current electrochemical synthesis, starting from water–acetonitrile–benzene mixtures containing 2-allylamino-5-methyl-1,3,4- thiadiazole and CuSiF6·4H2O. The electrochemical reduction of the saturated copper hexafluorosilicate water solution beneath the neatly poured layer of acetonitrile-benzene amdt solution resulted in the formation of cr...

Methane oxidation and attenuation of sulphur compounds in landfill top cover systems: Lab-scale tests.

Science.gov (United States)

Raga, Roberto; Pivato, Alberto; Lavagnolo, Maria Cristina; Megido, Laura; Cossu, Raffaello

2018-03-01

In this study, a top cover system is investigated as a control for emissions during the aftercare of new landfills and for old landfills where biogas energy production might not be profitable. Different materials were studied as landfill cover system in lab-scale columns: mechanical-biological pretreated municipal solid waste (MBP); mechanical-biological pretreated biowaste (PB); fine (PBS f ) and coarse (PBS c ) mechanical-biological pretreated mixtures of biowaste and sewage sludge, and natural soil (NS). The effectiveness of these materials in removing methane and sulphur compounds from a gas stream was tested, even coupled with activated carbon membranes. Concentrations of CO 2 , CH 4 , O 2 , N 2 , H 2 S and mercaptans were analysed at different depths along the columns. Methane degradation was assessed using mass balance and the results were expressed in terms of methane oxidation rate (MOR). The highest maximum and mean MOR were observed for MBP (17.2gCH 4 /m 2 /hr and 10.3gCH 4 /m 2 /hr, respectively). Similar values were obtained with PB and PBS c . The lowest values of MOR were obtained for NS (6.7gCH 4 /m 2 /hr) and PBS f (3.6gCH 4 /m 2 /hr), which may be due to their low organic content and void index, respectively. Activated membranes with high load capacity did not seem to have an influence on the methane oxidation process: MBP coupled with 220g/m 2 and 360g/m 2 membranes gave maximum MOR of 16.5gCH 4 /m 2 /hr and 17.4gCH 4 /m 2 /hr, respectively. Activated carbon membranes proved to be very effective on H 2 S adsorption. Furthermore, carbonyl sulphide, ethyl mercaptan and isopropyl mercaptan seemed to be easily absorbed by the filling materials. Copyright © 2017. Published by Elsevier B.V.

Roles for SH2 and SH3 domains in Lyn kinase association with activated FcepsilonRI in RBL mast cells revealed by patterned surface analysis.

Science.gov (United States)

Hammond, Stephanie; Wagenknecht-Wiesner, Alice; Veatch, Sarah L; Holowka, David; Baird, Barbara

2009-10-01

In mast cells, antigen-mediated cross-linking of IgE bound to its high-affinity surface receptor, FcepsilonRI, initiates a signaling cascade that culminates in degranulation and release of allergic mediators. Antigen-patterned surfaces, in which the antigen is deposited in micron-sized features on a silicon substrate, were used to examine the spatial relationship between clustered IgE-FcepsilonRI complexes and Lyn, the signal-initiating tyrosine kinase. RBL mast cells expressing wild-type Lyn-EGFP showed co-redistribution of this protein with clustered IgE receptors on antigen-patterned surfaces, whereas Lyn-EGFP containing an inhibitory point mutation in its SH2 domain did not significantly accumulate with the patterned antigen, and Lyn-EGFP with an inhibitory point mutation in its SH3 domain exhibited reduced interactions. Our results using antigen-patterned surfaces and quantitative cross-correlation image analysis reveal that both the SH2 and SH3 domains contribute to interactions between Lyn kinase and cross-linked IgE receptors in stimulated mast cells.

Thermal decomposition of FC(O)OCH3 and FC(O)OCH2CH3.

Science.gov (United States)

Berasategui, M; Argüello, G A; Burgos Paci, M A

2018-05-09

The thermal decomposition of methyl and ethyl formates has been extensively studied due to their importance in the oxidation of several fuels, pesticidal properties and their presence in interstellar space. We hitherto present the study of the thermal decomposition of methyl and ethyl fluoroformates, which could help in the elucidation of the reaction mechanisms. The reaction mechanisms were studied using FTIR spectroscopy in the temperature range of 453-733 K in the presence of different pressures of N2 as bath gas. For FC(O)OCH3 two different channels were observed; the unimolecular decomposition which is favored at higher temperatures and has a rate constant kFC(O)OCH3 = (5.3 ± 0.5) × 1015 exp[-(246 ± 10 kJ mol-1/RT)] (in units of s-1) and a bimolecular channel with a rate constant kFC(O)OCH3 = (1.6 ± 0.5) × 1011 exp[-(148 ± 10 kJ mol-1/RT)] (in units of s-1 (mol L)-1). However for ethyl formate, only direct elimination of CO2, HF and ethylene operates. The rate constants of the homogeneous first-order process fit the Arrhenius equation kFC(O)OCH2CH3 = (2.06 ± 0.09) × 1013 exp[-(169 ± 6 kJ mol-1/RT)] (in units of s-1). The difference between the mechanisms of the two fluoroformates relies on the stabilization of a six-centered transition state that only exists for ethyl formate. First principles calculations for the different channels were carried out to understand the dynamics of the decomposition.

CH3NH3Pb1−xMgxI3 perovskites as environmentally friendly photovoltaic materials

Directory of Open Access Journals (Sweden)

Y. D. Zhang

2018-01-01

Full Text Available In an effort to reduce the toxicity of Pb in perovskite solar cells, the band structures, electron and hole effective masses, and electronic and optical properties of the novel perovskites CH3NH3Pb1−xMgxI3 were predicted using density functional theory with the scalar relativistic generalized gradient approximation. The calculation results indicated that the introduction of the Mg component caused the band gaps of the CH3NH3Pb1−xMgxI3 compounds to exceed that of CH3NH3PbI3. The calculated absorption coefficients of the CH3NH3PbI3 and CH3NH3Pb1−xMgxI3 perovskites revealed that substituting 12.5 mol % of the Pb in CH3NH3PbI3 with Mg had little effect on the absorption ability. Surprisingly, it was also found that CH3NH3Pb0.75Mg0.25I3 retained up to 83% of the absorption performance relative to CH3NH3PbI3. This indicates that the amount of toxic Pb used in perovskite solar cells could be reduced by a quarter while retaining over 80% of the light-absorbing ability. In general, these novel CH3NH3Pb1−xMgxI3 (x ≤ 0.25 perovskites represent promising candidates for environmentally friendly light-harvesting materials for use in solar cells.

Dependence of Acetate-Based Antisolvents for High Humidity Fabrication of CH3NH3PbI3 Perovskite Devices in Ambient Atmosphere.

Science.gov (United States)

Yang, Fu; Kapil, Gaurav; Zhang, Putao; Hu, Zhaosheng; Kamarudin, Muhammad Akmal; Ma, Tingli; Hayase, Shuzi

2018-05-16

High-efficiency perovskite solar cells (PSCs) need to be fabricated in the nitrogen-filled glovebox by the atmosphere-controlled crystallization process. However, the use of the glovebox process is of great concern for mass level production of PSCs. In this work, notable efficient CH 3 NH 3 PbI 3 solar cells can be obtained in high humidity ambient atmosphere (60-70% relative humidity) by using acetate as the antisolvent, in which dependence of methyl, ethyl, propyl, and butyl acetate on the crystal growth mechanism is discussed. It is explored that acetate screens the sensitive perovskite intermediate phases from water molecules during perovskite film formation and annealing. It is revealed that relatively high vapor pressure and high water solubility of methyl acetate (MA) leads to the formation of highly dense and pinhole free perovskite films guiding to the best power conversion efficiency (PCE) of 16.3% with a reduced hysteresis. The devices prepared using MA showed remarkable shelf life stability of more than 80% for 360 h in ambient air condition, when compared to the devices fabricated using other antisolvents with low vapor pressure and low water solubility. Moreover, the PCE was still kept at 15.6% even though 2 vol % deionized water was added in the MA for preparing the perovskite layer.

Synthesis of the {beta}-phenethyl-mercaptan ({sup 35}S); Synthese du {beta}-phenethylmercaptan ({sup 35}S)

Energy Technology Data Exchange (ETDEWEB)

Wolff, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1957-07-01

{beta}-phenethyl-mercaptan ({sup 35}S) has been synthesized by action of elementary radioactive sulphur ({sup 35}S) on {beta}-phenethyl-magnesium-bromide, with a 90 per cent yield. (author) [French] Le {beta}-phenethylmercaptan ({sup 35}S) a ete synthetise par action du soufre radioactif elementaire ({sup 35}S) sur le bromure de {beta}-phenethylmagnesium, avec un rendement de 90 pour cent. (auteur)

Direct observation of unimolecular decay of CH{sub 3}CH{sub 2}CHOO Criegee intermediates to OH radical products

Energy Technology Data Exchange (ETDEWEB)

Fang, Yi; Liu, Fang; Lester, Marsha I., E-mail: milester@sas.upenn.edu [Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323 (United States); Klippenstein, Stephen J. [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2016-07-28

The unimolecular decay of carbonyl oxide intermediates, known as Criegee intermediates, produced in alkene ozonolysis is a significant source of OH radicals in the troposphere. Here, the rate of appearance of OH radical products is examined directly in the time-domain for a prototypical alkyl-substituted Criegee intermediate, CH{sub 3}CH{sub 2}CHOO, following vibrational activation under collision-free conditions. Complementary statistical Rice–Ramsperger–Kassel–Marcus calculations of the microcanonical unimolecular decay rate for CH{sub 3}CH{sub 2}CHOO are also carried out at energies in the vicinity of the barrier for 1,4 hydrogen atom transfer that leads to OH products. Tunneling through the barrier, derived from high level electronic structure calculations, contributes significantly to the decay rate. Infrared transitions of CH{sub 3}CH{sub 2}CHOO are identified in the CH stretch overtone region, which are detected by ultraviolet laser-induced fluorescence of the resultant OH products. The features observed are attributed to CH vibrational excitations and conformational forms utilizing insights from theory. Both experiment and theory yield unimolecular decay rates for CH{sub 3}CH{sub 2}CHOO of ca. 10{sup 7} s{sup −1}, which are slower than those obtained for syn-CH{sub 3}CHOO or (CH{sub 3}){sub 2}COO reported previously [Fang et al., J. Chem. Phys. 144, 061102 (2016)] at similar energies. Master equation modeling is also utilized to predict the thermal decay rate of CH{sub 3}CH{sub 2}CHOO under atmospheric conditions, giving a rate of 279 s{sup −1} at 298 K.

Fragmentation characteristics of the unstable [CH3 CO][radical sign] radicals generated by neutralization of [CH3CO]+ cations

Science.gov (United States)

Hop, C. E. C. A.; Holmes, J. L.

1991-03-01

The stability and fragmentation characteristics of [CH3 CO][radical sign] radicals, generated by vertical charge exchange between acetyl cations and permanent gases or metal vapours (He, Xe, NO, Cd, Na and K), were examined mass spectrometrically. Two dissociation reactions were observed, the losses of CH[radical sign]3 and H[radical sign]. The H[radical sign] loss reaction, the higher energy dissociation, became of greater importance as the exothermicity of the charge exchange was increased. Based on the analysis of the kinetic energy releases it was concluded that these decompositions arose from the population of two excited states of the [CH3 CO][radical sign] radical.

Dissociative electron attachment to methylhalides in 3-methylhexane glassy matrix

International Nuclear Information System (INIS)

Harada, K.; Irie, M.; Yoshida, H.

1976-01-01

Dissociative electron attachment reaction to CH 3 I, CH 3 Cl and CH 3 F in a 3-methylhexane glassy matrix was studied by determining the yield of trapped electrons and that of methyl radicals immediately after γ irradiation at 77 K as a function of the scavenger concentration. The efficiency of conversion from the trapped electrons to the methyl radicals was also studied by photobleaching the trapped electrons. The results obtained are (1) the dissociative electron attachment occurs to CH 3 F, for which the gas phase data indicate that the reaction is endothermic by 1.2 eV, during either the γ irradiation or the photobleaching, and (2) CH 3 F is relatively less efficient in scavenging photo-liberated electrons than in scavenging the electrons during the γ irradiation, whereas CH 3 I and CH 3 Cl are efficient scavengers for both the electrons. The dependence of the yields of the trapped electrons and the methyl radicals is discussed in terms of the electron-tunnelling mechanism and the epithermal electron-scavenging mechanism. (author)

The energy level alignment at the CH_3NH_3PbI_3/pentacene interface

International Nuclear Information System (INIS)

Ji, Gengwu; Zhao, Bin; Song, Fei; Zheng, Guanhaojie; Zhang, Xiaonan; Shen, Kongchao; Yang, Yingguo; Chen, Shi; Gao, Xingyu

2017-01-01

Highlights: • The Energy Level Alignment at the CH_3NH_3PbI_3/Pentacene Interface was resolved experimentally. • The downward band bending and the dipole found at the pentacene side would favorably drive holes away from the interface into pentacene. • A ∼0.7 eV offset between pentacene HOMO and CH_3NH_3PbI_3 VBM would be in favor of hole transfer whereas a ∼1.35 eV offset between pentacene LUMO and CH_3NH_3PbI_3 CBM should efficiently block the unwanted electron transfer from perovskite to pentacene. • Pentacene could be a viable hole transfer material candidate on perovskite to be explored in perovskite devices. - Abstract: Pentacene thin film on CH_3NH_3PbI_3 was studied by in-situ X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy to determine their interfacial energy level alignment. A 0.2 eV downward band bending together with a 0.1 eV interfacial dipole was found at the pentacene side, whereas there was no band bending found at the CH_3NH_3PbI_3 side. The offset between CH_3NH_3PbI_3 Valance Band Maximum (VBM) and pentacene Highest Occupied Molecular Orbital (HOMO) and that between CH_3NH_3PbI_3 Conduction Band Minimum (CBM) and pentacene Lowest Unoccupied Molecular Orbital (LUMO) was determined to be 0.7 and 1.35 eV, respectively. The band alignment at this interface is favor of efficient hole transfer, which suggests pentacene as a viable HTL candidate to be explored in perovskite solar cells.

Interactions of polyomavirus middle T with the SH2 domains of the pp85 subunit of phosphatidylinositol-3-kinase.

Science.gov (United States)

Yoakim, M; Hou, W; Liu, Y; Carpenter, C L; Kapeller, R; Schaffhausen, B S

1992-01-01

The binding of phosphatidylinositol-3-kinase to the polyomavirus middle T antigen is facilitated by tyrosine phosphorylation of middle T on residue 315. The pp85 subunit of phosphatidylinositol-3-kinase contains two SH2 domains, one in the middle of the molecule and one at the C terminus. When assayed by blotting with phosphorylated middle T, the more N-terminal SH2 domain is responsible for binding to middle T. When assayed in solution with glutathione S transferase fusions, both SH2s are capable of binding phosphorylated middle T. While both SH2 fusions can compete with intact pp85 for binding to middle T, the C-terminal SH2 is the more efficient of the two. Interaction between pp85 or its SH2 domains and middle T can be blocked by a synthetic peptide comprising the tyrosine phosphorylation sequence around middle T residue 315. Despite the fact that middle T can interact with both SH2s, these domains are not equivalent. Only the C-terminal SH2-middle T interaction was blocked by anti-SH2 antibody; the two SH2 fusions also interact with different cellular proteins. Images PMID:1380095

Conformational and spectroscopic study of xanthogen ethyl formates, ROC(S)SC(O)OCH₂CH₃. Isolation of CH₃CH₂OC(O)SH.

Science.gov (United States)

Juncal, Luciana C; Cozzarín, Melina V; Romano, Rosana M

2015-03-15

ROC(S)SC(O)OCH2CH3, with R=CH3-, (CH3)2CH- and CH3(CH2)2-, were obtained through the reaction between potassium xanthate salts, ROC(S)SK, and ethyl chloroformate, ClC(O)OCH2CH3. The liquid compounds were identified and characterized by (1)H and (13)C NMR and mass spectrometry. The conformations adopted by the molecules were studied by DFT methods. 6 conformers were theoretically predicted for R=CH3- and (CH3)2CH-, while the conformational flexibility of the n-propyl substituent increases the total number of feasible rotamers to 21. For the three molecules, the conformers can be associated in 3 groups, being the most stable the AS forms - the C=S double bond anti (A) with respect to the C-S single bond and the S-C single bond syn (S) with respect to the C=O double bond - followed by AA and SS conformers. The vibrational spectra were interpreted in terms of the predicted conformational equilibrium, presenting the ν(C=O) spectral region signals corresponding to the three groups of conformers. A moderated pre-resonance Raman enhancement of the ν(C=S) vibrational mode of CH3(CH2)2OC(S)SC(O)OCH2CH3 was detected, when the excitation radiation approaches the energy of a n→π∗ electronic transition associated with the C=S chromophore. UV-visible spectra in different solvents were measured and interpreted in terms of TD-DFT calculations. The unknown molecule CH3CH2OC(O)SH was isolated by the UV-visible photolysis of CH3OC(S)SC(O)OCH2CH3 isolated in Ar matrix, and also obtained as a side-product of the reaction between potassium xanthate salts, ROC(S)SK, and ethyl chloroformate, ClC(O)OCH2CH3. Copyright © 2014 Elsevier B.V. All rights reserved.

G331.512–0.103: An Interstellar Laboratory for Molecular Synthesis. I. The Ortho-to-para Ratios for CH3OH and CH3CN

Science.gov (United States)

Mendoza, Edgar; Bronfman, Leonardo; Duronea, Nicolas U.; Lépine, Jacques R. D.; Finger, Ricardo; Merello, Manuel; Hervías-Caimapo, Carlos; Gama, Diana R. G.; Reyes, Nicolas; Åke-Nyman, Lars

2018-02-01

Spectral line surveys reveal rich molecular reservoirs in G331.512–0.103, a compact radio source in the center of an energetic molecular outflow. In this first work, we analyze the physical conditions of the source by means of CH3OH and CH3CN. The observations were performed with the APEX Telescope. Six different system configurations were defined to cover most of the band within (292–356) GHz as a consequence, we detected a forest of lines toward the central core. A total of 70 lines of A/E–CH3OH and A/E–CH3CN were analyzed, including torsionally excited transitions of CH3OH ({ν }t=1). In a search for all the isotopologues, we identified transitions of 13CH3OH. The physical conditions were derived considering collisional and radiative processes. We found common temperatures for each A and E symmetry of CH3OH and CH3CN; the derived column densities indicate an A/E equilibrated ratio for both tracers. The results reveal that CH3CN and CH3OH trace a hot and cold component with {T}k∼ 141 K and {T}k∼ 74 K, respectively. In agreement with previous ALMA observations, the models show that the emission region is compact (≲ 5\\buildrel{\\prime\\prime}\\over{.} 5) with gas density n(H2) = (0.7–1)×107 cm‑3. The CH3OH/CH3CN abundance ratio and the evidences for prebiotic and complex organic molecules suggest a rich and active chemistry toward G331.512–0.103.

A novel mutation in the SH3BP2 gene causes cherubism: case report

Directory of Open Access Journals (Sweden)

Yu Shi-Feng

2006-12-01

Full Text Available Abstract Background Cherubism is a rare hereditary multi-cystic disease of the jaws, characterized by its typical appearance in early childhood, and stabilization and remission after puberty. It is genetically transmitted in an autosomal dominant fashion and the gene coding for SH3-binding protein 2 (SH3BP2 may be involved. Case presentation We investigated a family consisting of 21 members with 3 female affected individuals with cherubism from Northern China. Of these 21 family members, 17 were recruited for the genetic analysis. We conducted the direct sequence analysis of the SH3BP2 gene among these 17 family members. A disease-causing mutation was identified in exon 9 of the gene. It was an A1517G base change, which leads to a D419G amino acid substitution. Conclusion To our knowledge, the A1517G mutation has not been reported previously in cherubism. This finding is novel.

A two-state computational investigation of methane C--H and ethane C--C oxidative addition to [CpM(PH3)]n+ (M = Co, Rh, Ir; n = 0, 1).

Science.gov (United States)

Petit, Alban; Richard, Philippe; Cacelli, Ivo; Poli, Rinaldo

2006-01-11

Reductive elimination of methane from methyl hydride half-sandwich phosphane complexes of the Group 9 metals has been investigated by DFT calculations on the model system [CpM(PH(3))(CH(3))(H)] (M = Co, Rh, Ir). For each metal, the unsaturated product has a triplet ground state; thus, spin crossover occurs during the reaction. All relevant stationary points on the two potential energy surfaces (PES) and the minimum energy crossing point (MECP) were optimized. Spin crossover occurs very near the sigma-CH(4) complex local minimum for the Co system, whereas the heavier Rh and Ir systems remain in the singlet state until the CH(4) molecule is almost completely expelled from the metal coordination sphere. No local sigma-CH(4) minimum was found for the Ir system. The energetic profiles agree with the nonexistence of the Co(III) methyl hydride complex and with the greater thermal stability of the Ir complex relative to the Rh complex. Reductive elimination of methane from the related oxidized complexes [CpM(PH(3))(CH(3))(H)](+) (M = Rh, Ir) proceeds entirely on the spin doublet PES, because the 15-electron [CpM(PH(3))](+) products have a doublet ground state. This process is thermodynamically favored by about 25 kcal mol(-1) relative to the corresponding neutral system. It is essentially barrierless for the Rh system and has a relatively small barrier (ca. 7.5 kcal mol(-1)) for the Ir system. In both cases, the reaction involves a sigma-CH(4) intermediate. Reductive elimination of ethane from [CpM(PH(3))(CH(3))(2)](+) (M = Rh, Ir) shows a similar thermodynamic profile, but is kinetically quite different from methane elimination from [CpM(PH(3))(CH(3))(H)](+): the reductive elimination barrier is much greater and does not involve a sigma-complex intermediate. The large difference in the calculated activation barriers (ca. 12.0 and ca. 30.5 kcal mol(-1) for the Rh and Ir systems, respectively) agrees with the experimental observation, for related systems, of oxidatively

Iodine-catalyzed sp³ C-H bond activation by selenium dioxide: synthesis of diindolylmethanes and di(3-indolyl)selanides.

Science.gov (United States)

Naidu, P Seetham; Majumder, Swarup; Bhuyan, Pulak J

2015-11-01

An efficient reaction protocol was developed for the synthesis of several diindolylmethane derivatives via the [Formula: see text] C-H bond activation of aryl methyl ketones by [Formula: see text] and indoles in the presence of catalytic amounts of [Formula: see text] at 80 [Formula: see text] using dioxane as solvent. Unexpectedly, an interesting class of di(3-indolyl)selenide compounds was isolated when the reaction was carried out at room temperature.

Environmental Containment Property Estimation Using QSARs in an Expert System

Science.gov (United States)

1993-01-15

Soil Adsorption , Octanol- Water Partition Coefficients, Water Solubilities, Bioconcentration Factors and the Parachor. J. Agric. Food Chý’m., 1981. 29...CCOO CH3CO CH3SH CH3SH CH2COO CH2SH HCOO HCOO Furfural Furfural CH20 CH30 DOH (CH2OH)2 CH20 I I CH-O Br Br FCH20 C=C CH=C CNH2 CJ’-NH2 C=C Ci,2NH2 DMSO

Expression, refolding and crystallizations of the Grb2-like (GADS) C-terminal SH3 domain complexed with a SLP-76 motif peptide

International Nuclear Information System (INIS)

Faravelli, Alessandro; Dimasi, Nazzareno

2005-01-01

Several crystals of the Grb2-like C-terminal SH3 domain in complex with a motif peptide from the SLP-76 protein were obtained and characterized. The Grb2-like adaptor protein GADS is composed of an N-terminal SH3 domain, an SH2 domain, a proline-rich region and a C-terminal SH3 domain. GADS interacts through its C-terminal SH3 domain with the adaptor protein SLP-76, thus recruiting this protein and other associated molecules to the linker for activation of T-cell (LAT) protein. The DNA encoding the C-terminal SH3 domain of GADS (GADS-cSH3) was assembled synthetically using a recursive PCR technique and the protein was overexpressed in Escherichia coli, refolded and purified. Several crystals of this domain in complex with the SLP-76 peptide were obtained and characterized

Electrical Resistance of Ag-TS-S(CH2)(n-1)CH3//Ga2O3/EGaln Tunneling Junctions

NARCIS (Netherlands)