Search results for "carbon monoxide"
showing 10 items of 112 documents
Ligation Tunes Protein Reactivity in an Ancient Haemoglobin: Kinetic Evidence for an Allosteric Mechanism in Methanosarcina acetivorans Protoglobin
2012
Abstract: Protoglobin from Methanosarcina acetivorans (MaPgb) is a dimeric globin with peculiar structural properties such as a completely buried haem and two orthogonal tunnels connecting the distal cavity to the solvent. CO binding to and dissociation from MaPgb occur through a biphasic kinetics. We show that the heterogenous kinetics arises from binding to (and dissociation from) two tertiary conformations in ligation-dependent equilibrium. Ligation favours the species with high binding rate (and low dissociation rate). The equilibrium is shifted towards the species with low binding (and high dissociation) rates for the unliganded molecules. A quantitative model is proposed to describe t…
NO reduction by CO in the presence of water over gold supported catalysts on CeO2-Al2O3 mixed support, prepared by mechanochemical activation
2007
Abstract The reduction of NO by CO was studied on gold catalysts supported on ceria-alumina, prepared by mechanochemical activation. The samples were characterized by means of XRD, TPR, XPS and Raman spectroscopy. The influence of water in the feed on the catalytic activity was evaluated as well. It was established that the addition of hydrogen and water improves NO reduction activity by CO. The role of water was connected to the hydrogen production by WGS. The role of oxygen vacancies created in ceria structure in the presence of alumina was also discussed. The 100% selectivity to N2 at about 200 8C was kept in all cases of catalytic measurements, making the studied gold catalysts promisin…
Inflammatory mediators and other biomarkers in co-intoxicated patients after hyperbaric oxygen therapy (HBO2)
2016
Objective: The present study was conducted in attempt to identify reliable biomarkers in predicting the severity of neurological injury. Materials and methods: A number of 30 patients with confirmed CO poisoning and a number of 7 healthy control volunteers were involved into the study. All participants received at least 60 minutes of hyperbaric oxygen therapy (HBO2) at 2.5 atmospheres absolute (ATA). Standard blood gas analysis was performed on 10 mL venous blood samples obtained immediately before and after HBO2. Seven biomarkers and carboxyhemoglobin (COHb) levels were measured. Results: Following HBO2, all patients recovered fully and were discharged in stable condition. Significant diff…
Spectroscopic markers of the T-R quaternary transition in human hemoglobin
2004
n questo lavoro, usiamo un protocollo sol-gel per intrappolare e confrontare gli stati quaternari R e T di entrambi i deossigenati (deossiHb) ederivati di ossido di carbonio (HbCO) dell'emoglobina umana. La banda di assorbimento ottico del vicino infrarosso III e lo stretching di CO a infrarossibanda sono utilizzati per rilevare l'effetto della struttura quaternaria sulle proprietà spettrali di deoxyHb e HbCO; confronto con mioglobinaconsente una valutazione dei contributi terziari e quaternari ai turni di banda misurati. La RXLa transizione T è indicata per causare un bluspostamento della banda III di ~ 35 cm?1per deoxyHb e uno spostamento rosso della banda di allungamento CO di soli ~ 0…
Methane and carbon monoxide infrared emissions observed at the Canada-France-Hawaii Telescope during the collision of comet SL-9 with Jupiter
1995
Observations with the Fourier Transform Spectrometer were conducted in spectral ranges from 1.6 to 4.7 µm from July 17 to 21 (UT) on the hot plumes appearing on the limb as well as hours or days after the impacts. We present here an analysis of the methane emission observed at 3.3 µm some 10 min after the C impact, indicating the presence of a very small (less than 100 km wide) hot region with temperatures in the 750–1500 K range within the 0.1- to 0.01-mbar region. We also report the detection of CO emission at 4.7 µm 4.5 hrs after the L impact, indicative of a temperature of 274±10 K at the ∼1016 CO molec cm−2 level. The observations suggest that the stratospheric temperature decreases wi…
Synthesis of Cyclometalated Rhodium(III) Complexes. Study of the Carbonyl Insertion Reactions into the Rh-C Bond of the Metalocycle
1991
Abstract In this paper we report the preparation of new orthometalated rhodium(III) compounds of the formula Rh(oq)(AB)(PC), from Rh(oq)(Br)(PC)(H20), AB being a bidentade anionic ligand, oq= 8-oxyquinolate and PC = P(o-C6F4)Ph2. Their redox behaviour is also described. The reaction of Rh(Oq)(Br)(PC)(H20) [Oq = 5-Me-8-oxyquinolate (5-Meoq), 8-oxyquinolate] with carbon monoxide under pressure leads to expansion of the metalocycle ring by CO insertion into the Rh-C bond.
Five coordinate complexes of the type Rh(SnCl3)(NBD)L2
1983
Several new rhodium complexes of general formulation Rh(SnCl3)(NBD)L2 (L=P(OMe)3, P(OMe)2Ph, P(OMe)Ph2, P(OEt)3, P(OEt)2Ph, P(OEt)Ph2, P(O-i-Pr)3, P(OPh)3) have been prepared and characterized by elemental analysis and by i.r. and n.m.r. spectroscopy. The complexes show low or no conductivity in acetone solution and react with carbon monoxide (1 atm).
Review: monoclinic zirconia, its surface sites and their interaction with carbon monoxide
2015
This review concerns monoclinic zirconia, its surface sites and their probing with carbon monoxide. The surface sites and their modifications using thermal treatments with vacuum or reactive gases are also included. In this work, we present information on the nature and manipulation of hydroxyl species and their quantities on the surface, the different types of cationic sites where CO is adsorbed linearly and their energetics, as well as the surface sites and dynamics of formate formation. We also compare the surface concentrations of the different surface species to better understand the extent and nature of the interactions. Finally, we discuss some of the remaining open questions and how…
Au deposited on CeO2 prepared by a nanocasting route: A high activity catalyst for CO oxidation
2014
Abstract A set of catalysts comprised of gold on different CeO 2 supports has been prepared by a nanocasting route and characterized by several physicochemical techniques. These catalysts have been tested for CO oxidation and show outstanding catalytic activity. Higher calcination temperatures of the hard template, producing a poorly ordered silica template, have led to a higher amount of oxygen vacancies on the surface of CeO 2 . The presence of surface oxygen defects in the support combined with the deposition of Au nanoparticles ( ca. 3 nm) homogeneously dispersed on the CeO 2 support may explain the excellent behaviour for low temperature CO oxidation. Surprisingly, it has been observed…
CO Oxidation on Cationic Gold Clusters: A Theoretical Study
2008
Aiming at understanding the elementary steps governing the oxidation of CO catalyzed by dispersed or supported gold nanoclusters, the reactivity of molecular species, such as O2 and CO, on neutral and positively charged Au13 clusters have been studied using a DFT approach. Two CO oxidation mechanisms have been simulated, involving respectively the adsorption of CO and O2 on adjacent catalytic sites (two-sites mechanism) and the competitive interaction of the reactants on the same site (single-site mechanism). It is demonstrated that in the former scheme a definite interaction of CO and O2 with both the charged and neutral cluster is effective, but that a chemical reaction between the adsorb…