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Herein, the reaction mechanisms and kinetics for the HO2 + SO3 → HOSO2 + 3O2 reaction catalyzed by a water monomer, a water dimer and small clusters of sulfuric acid have been studied theoretically by quantum chemical methods and the Master Equation/Rice–Ramsperger–Kassel–Marcus (ME/RRKM) rate calculations. The calculated results show that when H2O is introduced into the HO2 + SO3 reaction, it not only enhances the stability of the reactant complexes by 9.0 kcal mol−1 but also reduces the energy of the transition state by 8.7 kcal mol−1. As compared with H2O, catalysts (H2O)2, H2SO4, H2SO4⋯H2O and (H2SO4)2 are more effective energetically, which not only results from a higher binding energy of 21.3–26.0 kcal mol−1 for the reactant complexes but also from a reduction of the energy of the transition states by 8.6–17.2 kcal mol−1. Effective rate constant calculations show that, as compared with H2O, catalysts (H2O)2, H2SO4, H2SO4⋯H2O and (H2SO4)2 can never become more efficient catalysts within the altitude range of 0–15 km due to their relatively lower concentrations. Besides, at 0 km altitude, the enhancement factor for the H2O and (k′WD1/ktot) (H2O)2-assisted HO2 + SO3 reaction within the temperature range of 280–320 K was respectively calculated to be 0.31%–0.34% and 0.16%–0.27%, while the corresponding enhancement factor of H2O and (H2O)2 at higher altitudes of 5–15 km was respectively found only 0.002%–0.12% and 0.00001%–0.022%, indicating that the contributions of H2O and (H2O)2 are not apparent in the gas-phase reaction of HO2 with SO3 especially at higher altitude. Overall, the present work will give a new insight into how a water monomer, a water dimer and small clusters of sulfuric acid catalyze the HO2 + SO3 → HOSO2 + 3O2 reaction. [ABSTRACT FROM AUTHOR]

NH2SO3H can directly participate in H2SO4–(CH3)2NH-based cluster formation, and thereby substantially enhance the cluster formation rate. Herein, the reaction mechanisms and kinetics for the formation of NH2SO3H from the hydrolysis of HNSO2 without and with neutral (H2O, (H2O)2, and (H2O)3), basic (NH3 and CH3NH2), and acidic (HCOOH, H2SO4, H2SO4⋯H2O, and (H2SO4)2) catalysts were studied theoretically at the CCSD(T)-F12/cc-pVDZ-F12//M06-2X/6-311+G(2df,2pd) level. The calculated results showed that neutral, basic, and acidic catalysts decrease the energy barrier by over 18.1 kcal mol−1; meanwhile, the product formation of NH2SO3H was more strongly bonded to neutral, basic, and acidic catalysts than to the reactants HNSO2 and H2O. This reveals that the reported neutral, basic, and acidic catalysts promote the formation of NH2SO3H from the hydrolysis of HNSO2 both kinetically and thermodynamically. Kinetic calculations using the master equation showed that (H2O)2 (100% RH) dominate over the other catalysts within the range of 0–10 km altitudes and 230–320 K with its rate ratio larger by at least 2.98 times, whereas HCOOH (3.2 × 109 molecules cm−3) is the most favorable catalysts at 15 km altitude in the troposphere. Overall, the present results will provide a definitive example that neutral, basic, and acidic catalysts have important influences on atmospheric reactions. [ABSTRACT FROM AUTHOR]

Dielectric barrier discharge (DBD) reactor at non-thermal plasma (NTP) in combination with catalysts was used to remove toluene in air. Several manganese oxides catalysts with ZSM-5 zeolite as the carrier have been prepared for plasma-catalytic degradation of toluene. The prepared catalysts were characterized utilizing the scanning electron microscopy (SEM), transmission electron microscope (TEM), H2 temperature-programmed reduction (H2-TPR), X-ray diffraction (XRD), and N2 adsorption–desorption. And the residence time, plasma power, toluene concentration and specific input energy, which are critical operating factors in this process, were investigated. The experiment proved that the catalysts significantly improved the degradation effect of NTP, the conversion increased from 58 to 91.5% after loading MnOx/ZSM-5-300 at 750 ppm, and the improving trend became more obvious with the increase of concentration. The degradation of toluene can reach 92.4% at the optimal process parameters of residence time 5.8 s, initial concentration 1000 ppm, input power 30 W, SIE 6000 J/L. The results of the evaluation indicate that it is very effective to use MnOx/ZSM-5 catalyst combined with DBD-plasma for synergistic degradation of toluene at room temperature and a relatively low energy consumption. [ABSTRACT FROM AUTHOR]

The carbonyl fluoride (CF2O) is one of the significant atmospheric molecules, and its hydrolysis reaction has been considered the most potential removal process in the earth's troposphere. In this article, the hydrolysis reaction of CF2O assisted by H2O, basic (NH3 and CH3NHCH3), and acidic (H2SO4, HCOOH, and CF3COOH) catalysts have theoretically investigated using quantum chemical methods. These catalysts significantly decrease the hydrolysis reaction of barrier height by 20.4–28.8 kcal mol−1. Here two H‐transfer mechanisms have been identified in these catalyzed hydrolytic reactions as asynchronous collaborative caused by base molecules and the synchronous collaborative led by H2O and acid molecules. In addition, the rate coefficient and relative rate of all catalytic reactions have calculated using conventional transition state theory (TST) over a temperature range of 280–320 K. The results show that H2SO4 has the best catalytic effect without considering the concentration of catalyst molecules in the atmosphere. On the contrary, a high concentration of HCOOH (10 ppbv) is dominant in the catalytic reaction when considered the concentrations of catalyst molecules. In this work, it was identified that the catalytic efficiencies of H2O, acid and base molecules upon addition reaction between CF2O and H2O is not only related to their catalytic mechanisms but also depending upon their concentrations in the atmosphere. [ABSTRACT FROM AUTHOR]

The hydrolysis reaction of CH2OO with water and water clusters is believed to be a dominant sink for the CH2OO intermediate in the atmosphere. However, the favorable route for the hydrolysis of CH2OO with water clusters is still unclear. Here global minimum searching using the Tsinghua Global Minimum program has been introduced to find the most stable geometry of the CH2OO⋯(H2O)n (n = 1–4) complex firstly. Then, based on these stable complexes, favorable hydrolysis of CH2OO with (H2O)n (n = 1–4) has been investigated using the quantum chemical method of CCSD(T)-F12a/cc-pVDZ-F12//B3LYP/6-311+G(2d,2p) and canonical variational transition state theory with small curvature tunneling. The calculated results have revealed that, although the contribution of CH2OO + (H2O)2 is the most obvious in the hydrolysis of CH2OO with (H2O)n (n = 1–4), the hydrolysis of CH2OO with (H2O)3 is not negligible in atmospheric gas-phase chemistry as its rate is close to the rate of the CH2OO + H2O reaction. The calculated results also show that, in a clean atmosphere, the CH2OO + (H2O)n (n = 1–2) reaction competes well with the CH2OO + SO2 reaction at 298 K when the concentrations of (H2O)n (n = 1–2) range from 20% relative humidity (RH) to 100% RH, and SO2 is 2.46 × 1011 molecules per cm3. Meanwhile, when the RH is higher than 40%, it is a new prediction that the CH2OO + (H2O)3 reaction can also compete well with the CH2OO + SO2 reaction at 298 K. Besides, Born–Oppenheimer molecular dynamics simulation results show that all the favorable channels of the CH2OO + (H2O)n (n = 1–3) reaction cannot react on a time scale of 100 ps in the NVT simulation. However, the NVE simulation results show that the CH2OO + (H2O)3 reaction can be finished well at 8.5 ps, indicating that the gas phase reaction of CH2OO + (H2O)3 is not negligible in the atmosphere. Overall, the present results have provided a definitive example of how the favorable hydrolysis of important atmospheric species with (H2O)n (n = 1–4) takes place, which will stimulate one to consider the favorable hydrolysis of water and water clusters with other Criegee intermediates and other important atmospheric species. [ABSTRACT FROM AUTHOR]

In order to investigate the influence of the narrow gap groove on the arc shape in the narrow gap swing arc welding process, magnetohydrodynamics theory was used to establish the three-dimensional symmetric mathematical model of the welding sidewall of the narrow gap welding arc based on the actual welding process. The numerical calculation of narrow gap welding arc was realized through the secondary development of the FLUENT user-defined-function (UDF), and the calculated arc shape was in good agreement with the experimental results. The distribution the flow field and temperature field of the narrow-gap welding arc were obtained. The results show that the magnetic induction intensity of the arc far away from the sidewall is greater than that near the sidewall. The plasma flow field, pressure field and temperature field are deflected toward the sidewall. The plasma at the bottom of the arc moves along the tangent of the molten pool to the bottom of the concave surface of the weld due to the influence of the narrow gap weld morphology, which affects the distribution of the current density and temperature field above the molten pool. [ABSTRACT FROM AUTHOR]

A detailed theoretical study on the reaction mechanisms for the formations of H2O2 + 3O2 from the self‐reaction of HO2 radicals under the effect of NH3, H3N···H2O, and H2SO4 catalysts was performed using the CCSD(T)/CBS//M06‐2X/aug‐cc‐pVTZ method. The rate constant was computed using canonical variational transition state theory (CVT) with small curvature tunneling (SCT). Our results indicate that NH3‐, H3N···H2O‐, and H2SO4‐catalyzed reactions could proceed through both one‐step and stepwise routes. Calculated rate constants show that the catalyzed routes in the presence of the three catalysts all prefer stepwise pathways. Compared to the catalytic efficiency of H2O, the efficiencies of NH3, H3N···H2O, and H2SO4 are much lower due to their smaller relative concentrations. The present results have provided a definitive example of how basic and acidic catalysts influence the atmospheric reaction of HO2 + HO2 → H2O2 + 3O2. These results further encourage one to consider the effects of basic and acidic catalysts on the related atmospheric reactions. Thus, the present investigation should have broad implications in the gas‐phase reactions of the atmosphere. [ABSTRACT FROM AUTHOR]

A detailed effects of catalyst X (X = H2O, (H2O)2, NH3, NH3···H2O, H2O···NH3, HCOOH and H2SO4) on the HO4H → O3 + H2O reaction have been investigated by using quantum chemical calculations and canonical vibrational transition state theory with small curvature tunnelling. The calculated results show that (H2O)2-catalysed reactions much faster than H2O-catalysed one because of the former bimolecular rate constant larger by 2.6–25.9 times than that of the latter one. In addition, the basic H2O···NH3 catalyst was found to be a better than the neutral catalyst of (H2O)2. However it is marginally less efficient than the acidic catalysts of HCOOH, and H2SO4. The effective rate constant (k't) in the presence of catalyst X have been assessed. It was found from k't that H2O (at 100% RH) completely dominates over all other catalysts within the temperature range of 280–320 K at 0 km altitude. However, compared with the rate constant of HO4H → H2O + O3 reaction, the keff values for H2O catalysed reaction are smaller by 1–2 orders of magnitude, indicating that the catalytic effect of H2O makes a negligible contribution to the gas phase reaction of HO4H → O3 + H2O. Highlights A detailed effects of catalyst of H2O, (H2O)2, NH3, NH3···H2O, H2O···NH3, HCOOH and H2SO4 on the HO4H → O3 + H2O reaction has been performed. From energetic viewpoint, H2SO4 exerts the strongest catalytic role in HO4H → O3 + H2O reaction as compared with the other catalysts. At 0 km altitude H2O (at 100% RH) completely dominates over all other catalysts within the temperature range of 280–320 K. HO4H → H2O + O3 reaction with H2O cannot be compete with the reaction without catalyst, due to the fact that the effective rate constants in the presence of H2O are smaller. [ABSTRACT FROM AUTHOR]

Total fertilization failure (TFF), which is the failure of fertilization in all oocytes, occurs in 1%‐3% of intracytoplasmic sperm injection (ICSI) cycles. However, the sperm‐related factors that cause fertilization failure in humans are still largely unknown. Here, we identified three novel homozygous variations in the PLCZ1 gene in a recessive inheritance pattern in three consanguineous families, which all located in a key catalytic domain, and predicted to modify its secondary structure and thus impair its hydrolytic activity. Moreover, immunofluorescent staining revealed that PLCζ in mutant sperm exhibited abnormal localization patterns. ICSI‐AOA resulted in an increased rate of normal fertilization compared with previous ICSI cycles (75.0% vs 2.2%, P <.001). In summary, we identified three novel homozygous variations in PLCZ1 that led to poor or failed fertilization that could be overcame by ICSI‐AOA. [ABSTRACT FROM AUTHOR]