Kinetics of the Simplest Criegee Intermediate Reaction with Water Vapor: Revisit and Isotope Effect.

The kinetics of the simplest Criegee intermediate (CHOO) reaction with water vapor was revisited. By improving the signal-to-noise ratio and the precision of water concentration, we found that the kinetics of CHOO involves not only two water molecules but also one and three water molecules. Our experimental results suggest that the decay of CHOO can be described as d[CHOO]/d = -[CHOO]; = + [water] + [water] + [water]; = (4.

Reaction Kinetics of Criegee Intermediates with Nitric Acid.

This work investigated the reaction kinetics of HNO with four Criegee intermediates (CIs): CHOO, (CH)COO, methyl vinyl ketone oxide (MVKO), and methacrolein oxide (MACRO). Our results show that these reactions are extremely fast with rate coefficients of (1.51 ± 0.

Absolute photodissociation cross sections of thermalized methyl vinyl ketone oxide and methacrolein oxide.

Methyl vinyl ketone oxide (MVKO) and methacrolein oxide (MACRO) are resonance-stabilized Criegee intermediates which are formed in the ozonolysis reaction of isoprene, the most abundant unsaturated hydrocarbon in the atmosphere. The absolute photodissociation cross sections of MVKO and MACRO were determined by measuring their laser depletion fraction at 352 nm, which was deduced from their time-resolved UV-visible absorption spectra. After calibrating the 352 nm laser fluence with the photodissociation of NO, for which the absorption cross section and photodissociation quantum yield are well known, the photodissociation cross sections of thermalized (299 K) MVKO and MACRO at 352 nm were determined to be (3.

Substituent Effect in the Reactions between Criegee Intermediates and 3-Aminopropanol.

Via intramolecular H atom transfer, 3-aminopropanol is more reactive toward Criegee intermediates, in comparison with amines or alcohols. Here we accessed the substituent effect of Criegee intermediates in their reactions with 3-aminopropanol. Through real-time monitoring the concentrations of two Criegee intermediates with their strong UV absorption at 340 nm, the experimental rate coefficients at 298 K (100-300 Torr) were determined to be (1.

A rapid degradation of calponin 2 is required for cytokinesis.

Calponin 2 is an actin cytoskeleton-associated protein and plays a role in regulating cell motility-related functions such as phagocytosis, migration, and division. We previously reported that overexpression of calponin 2 inhibits the rate of cell proliferation. To investigate the underlying mechanism, our present study found that the levels of endogenous calponin 2 in NIH3T3 and HEK293 cells rapidly decreased before cell division characterized by an absence at the actin contractile ring.

Surprisingly long lifetime of methacrolein oxide, an isoprene derived Criegee intermediate, under humid conditions.

Ozonolysis of isoprene, the most abundant alkene, produces three distinct Criegee intermediates (CIs): CHOO, methyl vinyl ketone oxide (MVKO) and methacrolein oxide (MACRO). The oxidation of SO by CIs is a potential source of HSO, an important precursor of aerosols. Here we investigated the UV-visible spectroscopy and reaction kinetics of thermalized MACRO.

Kinetics of Unimolecular Decay of Methyl Vinyl Ketone Oxide, an Isoprene-Derived Criegee Intermediate, under Atmospherically Relevant Conditions.

Isoprene is the most abundant unsaturated hydrocarbon in the atmosphere. Ozonolysis of isoprene produces methyl vinyl ketone oxide (MVKO), which may react with atmospheric SO, formic acid, and other important species at substantial levels. In this study, we utilized ultraviolet absorption to monitor the unimolecular decay kinetics of -MVKO in real time at 278-319 K and 100-503 Torr.

Intercalated disc protein Xinβ is required for Hippo-YAP signaling in the heart.

Intercalated discs (ICD), specific cell-to-cell contacts that connect adjacent cardiomyocytes, ensure mechanical and electrochemical coupling during contraction of the heart. Mutations in genes encoding ICD components are linked to cardiovascular diseases. Here, we show that loss of Xinβ, a newly-identified component of ICDs, results in cardiomyocyte proliferation defects and cardiomyopathy.

Reactions of Criegee Intermediates are Enhanced by Hydrogen-Atom Relay Through Molecular Design.

We report a type of highly efficient double hydrogen atom transfer (DHAT) reaction. The reactivities of 3-aminopropanol and 2-aminoethanol towards Criegee intermediates (syn- and anti-CH CHOO) were found to be much higher than those of n-propanol and propylamine. Quantum chemistry calculation has confirmed that the main mechanism of these very rapid reactions is DHAT, in which the nucleophilic attack of the NH group is catalyzed by the OH group which acts as a bridge of HAT.

The role of the iodine-atom adduct in the synthesis and kinetics of methyl vinyl ketone oxide-a resonance-stabilized Criegee intermediate.

Isoprene is the most abundant alkene in the atmosphere. Ozonolysis of isoprene produces three very reactive carbonyl oxides (Criegee intermediates), including formaldehyde oxide, methyl vinyl ketone oxide (MVKO, CH3(C2H3)COO), and methacrolein oxide. The latter two Criegee intermediates are resonance-stabilized due to the vinyl group.

Direct kinetic measurements and theoretical predictions of an isoprene-derived Criegee intermediate.

Isoprene has the highest emission into Earth's atmosphere of any nonmethane hydrocarbon. Atmospheric processing of alkenes, including isoprene, via ozonolysis leads to the formation of zwitterionic reactive intermediates, known as Criegee intermediates (CIs). Direct studies have revealed that reactions involving simple CIs can significantly impact the tropospheric oxidizing capacity, enhance particulate formation, and degrade local air quality.

Unimolecular decomposition rates of a methyl-substituted Criegee intermediate -CHCHOO.

Criegee intermediates play important roles in atmospheric chemistry. Methyl Criegee intermediate, CHCHOO, has two conformers, - and -conformers. -CHCHOO would undergo fast unimolecular decomposition to form OH radical 1,4 H-atom transfer.

Effects of water vapor on the reaction of CHOO with NH.

The reaction of the simplest Criegee intermediate, CHOO, with ammonia and water vapor has been investigated at 278-308 K and under 100-760 Torr by monitoring the strong UV absorption of CHOO. We found that the observed decay rate of CHOO becomes much larger when ammonia and water vapor are both present; the combinational effect of ammonia and water vapor is significantly greater than the sum of their individual contributions, revealing a strong synergic effect. The kinetic data are consistent with a termolecular process of CHOO + NH + HO reaction, of which the reaction rate coefficient was determined to be k = (8.

Hydrogen-Bonding Mediated Reactions of Criegee Intermediates in the Gas Phase: Competition between Bimolecular and Termolecular Reactions and the Catalytic Role of Water.

Criegee intermediates have substantial Zwitterionic character and interact strongly with hydrogen-bonding molecules like HO, NH, CHOH, etc. Some of the observed reactions between Criegee intermediates and hydrogen-bonding molecules exhibit third-order kinetics. The experimental data indicate that these termolecular reactions involve one Criegee intermediate and two hydrogen-bonding molecules; quantum chemistry calculation shows that one of the hydrogen-bonding molecules acts as a catalytic bridge, which receives a hydrogen atom and donates another one.

Temperature and isotope effects in the reaction of CHCHOO with methanol.

Carbonyl oxides, also known as Criegee intermediates, are generated from ozonolysis of unsaturated hydrocarbons in the atmosphere. Alcohols are often used as a scavenger of the Criegee intermediates in laboratory studies. In this work, the reaction kinetics of CHCHOO with methanol vapor was investigated at various temperatures, pressures, and isotopic substitutions using time-resolved UV absorption spectroscopy.

Temperature-Dependent Rate Coefficient for the Reaction of CHSH with the Simplest Criegee Intermediate.

The kinetics of the reaction of the simplest Criegee intermediate CHOO with CHSH was measured with transient IR absorption spectroscopy in a temperature-controlled flow reaction cell, and the bimolecular rate coefficients were measured from 278 to 349 K and at total pressure from 10 to 300 Torr. The measured bimolecular rate coefficient at 298 K and 300 Torr is (1.01 ± 0.

Synergy of Water and Ammonia Hydrogen Bonding in a Gas-Phase Reaction.

We report a very significant cooperative effect of water-ammonia hydrogen bonding in their reactions with a Criegee intermediate, syn-CHCHOO. Under near ambient conditions, we found that the reaction of syn-CHCHOO with NH becomes much faster (by up to 138 times) at high humidity. Intriguingly, merely adding NH (or HO) alone has almost no effect on the rate of syn-CHCHOO decay.

Criegee Intermediate Reaction with Alcohol Is Enhanced by a Single Water Molecule.

The role of water in gas-phase reactions has gained considerable interest. Here we report a direct kinetic measurement of the reaction of syn-CHCHOO (a Criegee intermediate or carbonyl oxide) with methanol at various relative humidity (RH = 0-80%) under near-ambient conditions (298 K, 250-755 Torr). The data indicate that a single water molecule expedites the reaction by up to a factor of three.

Kinetics of the reaction of the simplest Criegee intermediate with ammonia: a combination of experiment and theory.

The kinetics of the reaction of the simplest Criegee intermediate (CH2OO) with ammonia has been measured under pseudo-first-order conditions with two different experimental methods. We investigated the rate coefficients at 283, 298, 308, and 318 K at a pressure of 50 Torr using an OH laser-induced fluorescence (LIF) method. Weak temperature dependence of the rate coefficient was observed, which is consistent with the theoretical activation energy of -0.

Absolute Infrared Absorption Cross Section of the Simplest Criegee Intermediate Near 1285.7 cm.

The ν fundamental of the simplest Criegee intermediate, CHOO, has been monitored with high-resolution infrared (IR) transient absorption spectroscopy under total pressures of 4-94 Torr. This IR spectrum provides an unambiguous identification of CHOO and is potentially useful to determine the number density of CHOO in various laboratory studies. Here we utilized an ultraviolet (UV) and IR coupled spectrometer to measure the UV and IR absorption spectra of CHOO simultaneously; the absolute IR cross section can then be determined by using a known UV cross section.

Critical Roles of Xirp Proteins in Cardiac Conduction and Their Rare Variants Identified in Sudden Unexplained Nocturnal Death Syndrome and Brugada Syndrome in Chinese Han Population.

Background: Sudden unexplained nocturnal death syndrome (SUNDS) remains an autopsy negative entity with unclear etiology. Arrhythmia has been implicated in SUNDS. Mutations/deficiencies in intercalated disc components have been shown to cause arrhythmias.

Reactivity of Criegee Intermediates toward Carbon Dioxide.

Recent theoretical work by Kumar and Francisco suggested that the high reactivity of Criegee intermediates (CIs) could be utilized for designing efficient carbon capture technologies. Because the anti-CHCHOO + CO reaction has the lowest barrier in their study, we chose to investigate it experimentally. We probed anti-CHCHOO with its strong UV absorption at 365 nm and measured the rate coefficient to be ≤2 × 10 cm molecule s at 298 K, which is consistent with our theoretical value of 2.

Kinetics of the simplest Criegee intermediate reaction with ozone studied using a mid-infrared quantum cascade laser spectrometer.

The kinetics of the reaction of CHOO with ozone has been studied by monitoring CHOO using time-resolved infrared (IR) absorption spectroscopy, which utilized the fast chirped IR pulse train from a quantum cascade laser [J. Chem. Phys.

High resolution quantum cascade laser spectroscopy of the simplest Criegee intermediate, CHOO, between 1273 cm and 1290 cm.

The region 1273-1290 cm of the ν fundamental of the simplest Criegee intermediate, CHOO, has been measured using a quantum cascade laser transient absorption spectrometer, which offers greater sensitivity and spectral resolution (<0.004 cm) than previous works based on thermal light sources. Gas phase CHOO was generated from the reaction of CHI + O at 298 K and 4 Torr.