Gas-Phase Mechanism of O^.-/Ni²⁺-Mediated Methane Conversion to Formaldehyde

The gas-phase reaction of NiAl2O4+ with CH4 is studied by mass spectrometry in combination with vibrational action spectroscopy and density functional theory (DFT). Two product ions, NiAl2O4H+ and NiAl2O3H2+, are identified in the mass spectra. The DFT calculations predict that the global minimum-energy isomer of NiAl2O4+ contains Ni in the +II oxidation state and features a terminal Al−O.- oxygen radical site. They show that methane can react along two competing pathways leading to formation of either a methyl radical (CH3⋅) or formaldehyde (CH2O). Both reactions are initiated by hydrogen atom transfer from methane to the terminal O.- site, followed by either CH3⋅ loss or CH3⋅ migration to an O2- site next to the Ni2+ center. The CH3⋅ attaches as CH3+ to O2- and its unpaired electron is transferred to the Ni-center reducing it to Ni+. The proposed mechanism is experimentally confirmed by vibrational spectroscopy of the reactant and two different product ions

Gas-Phase Mechanism of O^.-/Ni²⁺-Mediated Methane Conversion to Formaldehyde

The gas-phase reaction of NiAl2O4+ with CH4 is studied by mass spectrometry in combination with vibrational action spectroscopy and density functional theory (DFT). Two product ions, NiAl2O4H+ and NiAl2O3H2+, are identified in the mass spectra. The DFT calculations predict that the global minimum-energy isomer of NiAl2O4+ contains Ni in the +II oxidation state and features a terminal Al−O.- oxygen radical site. They show that methane can react along two competing pathways leading to formation of either a methyl radical (CH3⋅) or formaldehyde (CH2O). Both reactions are initiated by hydrogen atom transfer from methane to the terminal O.- site, followed by either CH3⋅ loss or CH3⋅ migration to an O2- site next to the Ni2+ center. The CH3⋅ attaches as CH3+ to O2- and its unpaired electron is transferred to the Ni-center reducing it to Ni+. The proposed mechanism is experimentally confirmed by vibrational spectroscopy of the reactant and two different product ions

In vitro factor XIII supplementation increases clot firmness in Rotation Thromboelastometry (ROTEM®)

Factor XIII (F XIII) is an essential parameter for final clot stability. The purpose of this study was to determine the impact of the addition of factor (F)XIII on clot stability as assessed by Rotation Thromboelastometry (ROTEM(R)). In 90 intensive care patients ROTEM(R) measurements were performed after in vitro addition of F XIII 0.32 IU, 0.63 IU, 1.25 IU and compared to diluent controls (DC; aqua injectabile) resulting in approximate F XIII concentrations of 150, 300 and 600%. Baseline measurements without any additions were also performed. The following ROTEM(R) parameters were measured in FIBTEM and EXTEM tests: clotting time (CT), clot formation time (CFT), maximum clot firmness (MCF), maximum lysis (ML), maximum clot elasticity (MCE) and a-angle (aA). Additionally, laboratory values for FXIII, fibrinogen (FBG), platelets and haematocrit were contemporaneously determined. In the perioperative patient population mean FBG concentration was elevated at 5.2 g/l and mean FXIII concentration was low at 62%. The addition of FXIII led to a FBG concentration-dependent increase in MCF both in FIBTEM and EXTEM. Mean increases in MCF (FXIII vs. DC) of approximately 7 mm and 6 mm were observed in FIBTEM and EXTEM, respectively. F XIII addition also led to decreased CFT, increased aA, and reduced ML in FIBTEM and EXTEM. In vitro supplementation of FXIII to supraphysiologic levels increases maximum clot firmness, accelerates clot formation and increases clot stability in EXTEM and FIBTEM as assayed by ROTEM(R) in perioperative patients with high fibrinogen and low FXIII levels

Relative concentrations of haemostatic factors and cytokines in solvent/detergent-treated and fresh-frozen plasma

Background Indications, efficacy, and safety of plasma products are highly debated. We compared the concentrations of haemostatic proteins and cytokines in solvent/detergent-treated plasma (SDP) and fresh-frozen plasma (FFP). Methods Concentrations of the following parameters were measured in 25 SDP and FFP samples: fibrinogen (FBG), factor (F) II, F V, F VII, F VIII, F IX, F X, F XIII, von Willebrand factor (vWF), D-Dimers, ADAMTS-13 protease, tumour necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, IL-8, and IL-10. Results Mean FBG concentrations in SDP and FFP were similar, but in FFP, the range was larger than in SDP (P<0.01). Mean F II, F VII, F VIII, F IX, and F XIII levels did not differ significantly. Higher concentrations of F V (P<0.01), F X (P<0.05), vWF (P<0.01), and ADAMTS-13 (P<0.01) were found in FFP. With the exception of F VIII and F IX, the range of concentrations for all of these factors was smaller (P<0.05) in SDP than in FFP. Concentrations of TNF-α, IL-8, and IL-10 (all P<0.01) were higher in FFP than in SDP, again with a higher variability and thus larger ranges (P<0.01). Conclusions Coagulation factor content is similar for SDP and FFP, with notable exceptions of less F V, vWF, and ADAMTS-13 in SDP. Cytokine concentrations (TNFα, IL-8, and IL-10) were significantly higher in FFP. The clinical relevance of these findings needs to be established in outcome studie

Gas phase structures and charge localization in small aluminum oxide anions: Infrared photodissociation spectroscopy and electronic structure calculations

We use cryogenic ion trap vibrational spectroscopy in combination with quantum chemical calculations to study the structure of mono- and dialuminum oxide anions. The infrared photodissociation spectra of D2-tagged AlO1-4− and Al2O3-6− are measured in the region from 400 to 1200 cm−1. Structures are assigned based on a comparison to simulated harmonic and anharmonic IR spectra derived from electronic structure calculations. The monoaluminum anions contain an even number of electrons and exhibit an electronic closed-shell ground state. The Al2O3-6− anions are oxygen-centered radicals. As a result of a delicate balance between localization and delocalization of the unpaired electron, only the BHLYP functional is able to qualitatively describe the observed IR spectra of all species with the exception of AlO3−. Terminal Al–O stretching modes are found between 1140 and 960 cm−1. Superoxo and peroxo stretching modes are found at higher (1120-1010 cm−1) and lower energies (850-570 cm−1), respectively. Four modes in-between 910 and 530 cm−1 represent the IR fingerprint of the common structural motif of dialuminum oxide anions, an asymmetric four-member Al–(O)2–Al ring

Dinitrogen Activation in the Gas Phase: Spectroscopic Characterization of C–N Coupling in the V₃C⁺ + N₂ Reaction

We report on cluster-mediated C–N bond formation in the gas phase using N2 as a nitrogen source. The V3C+ + N2 reaction is studied by a combination of ion-trap mass spectrometry with infrared photodissociation (IRPD) spectroscopy and complemented by electronic structure calculations. The proposed reaction mechanism is spectroscopically validated by identifying the structures of the reactant and product ions. V3C+ exhibits a pyramidal structure of C1 symmetry. N2 activation is initiated by adsorption in an end-on fashion at a vanadium site, followed by spontaneous cleavage of the N≡N triple bond and subsequent C−N coupling. The IRPD spectrum of the metal nitride product [NV3(C=N)]+ exhibits characteristic C=N double bond (1530 cm-1) and V-N single bond (770, 541 and 522 cm-1) stretching bands

Site-specific vibrational spectral signatures of water molecules in the magic H₃O⁺(H₂O)₂₀ and Cs⁺(H₂O)₂₀ clusters

Theoretical models of proton hydration with tens of water molecules indicate that the excess proton is embedded on the surface of clathrate-like cage structures with one or two water molecules in the interior. The evidence for these structures has been indirect, however, because the experimental spectra in the critical H-bonding region of the OH stretching vibrations have been too diffuse to provide band patterns that distinguish between candidate structures predicted theoretically. Here we exploit the slow cooling afforded by cryogenic ion trapping, alongwith isotopic substitution, to quench water clusters attached to the H3O+ and Cs+ ions into structures that yield well-resolved vibrational bands over the entire 215- to 3,800-cm−1 range. The magic H3O+ (H2O)20 cluster yields particularly clear spectral signatures that can, with the aid of ab initio predictions, be traced to specific classes of network sites in the predicted pentagonal dodecahedron H-bonded cage with the hydronium ion residing on the surface

Experimentelle Bestimmung des aktiven Zentrums im heteronuklearen Redox‐System [AlVO_x]^+./CO/N₂O (x=3, 4) durch Gasphasen‐Infrarotspektroskopie

Das aktive Zentrum der Sauerstoffatom‐Übertragungsreaktion[AlVO4]+.+CO→[AlVO3]+.+CO2. IHe‐ und CO‐Komplexe dieser heteronuklearen Metalloxidkationen zeigen, dass [AlVO3]+. im Unterschied zu [AlVO4]+. keine endständige Al−Ot‐Gruppe mehr enthält, sehr wohl aber noch die V=Ot‐Gruppe aufweist. Somit entspricht die Al−Ot‐Einheit, in Einklang mit der theoretischen Voraussage, dem aktiven Zentrum des Redox‐Systems [AlVOx]+./CO/N2O (x=3, 4)

The unacknowledged legacy

This paper presents a critical discussion of the treatment of mimetic art, and particularly poetry and the theatre, in the work of the Athenian philosopher Plato (427-347 BC). It centres on Plato's discussion of the corrupting powers of the arts in the Republic, and the implications that his fierce attack on poetry and theatre have for his construction of the ideal polity. The legacy of Platonic ideas in later elaborations of the corrupting power of the arts is discussed. Furthermore, the paper investigates the relationship between current debates on cultural policy and the Platonic idea that the transformative powers of the arts ought to be harnessed by the state to promote a just society. The conclusion thus reached is that “instrumental cultural policy”, rather then being a modern invention, was in fact first theorized precisely in Plato's Republic