Correction to “Computational Study of the Thermochemistry of N₂O₅ and the Kinetics of the Reaction N₂O₅ + H₂O → 2 HNO₃”

Correction to “Computational Study of the Thermochemistry of N₂O₅ and the Kinetics of the Reaction N₂O₅ + H₂O → 2 HNO₃

Computational Study of the Thermochemistry of N₂O₅ and the Kinetics of the Reaction N₂O₅ + H₂O → 2 HNO₃

The multistructural method for torsional anharmonicity (MS-T) is employed to compute anharmonic conformationally averaged partition functions which then serve as the basis for the calculation of thermochemical parameters for N₂O₅ over the temperature range 0–3000 K, and thermal rate constants for the hydrolysis reaction N₂O₅ + H₂O → 2 HNO₃ over the temperature range 180–1800 K. The M06-2X hybrid meta-GGA density functional paired with the MG3S basis set is used to compute the properties of all stationary points and the energies, gradients, and Hessians of nonstationary points along the reaction path, with further energy refinement at stationary points obtained via single-point CCSD­(T)-F12a/cc-pVTZ-F12 calculations including corrections for core–valence and scalar relativistic effects. The internal rotations in dinitrogen pentoxide are found to generate three structures (conformations) whose contributions are included in the partition function via the MS-T formalism, leading to a computed value for <i>S</i>°_298.15(N₂O₅) of 353.45 J mol^–1 K^–1. This new estimate for <i>S</i>°_298.15(N₂O₅) is used to reanalyze the equilibrium constants for the reaction NO₃ + NO₂ = N₂O₅ measured by Osthoff et al. [Phys. Chem. Chem. Phys. 2007, 9, 5785−5793] to arrive at Δ_f<i>H</i>_298.15^°(N₂O₅) = 14.31 ± 0.53 kJ mol^–1 via the third law method, which compares well with our computed <i>ab initio</i> value of 13.53 ± 0.56 kJ mol^–1. Finally, multistructural canonical variational-transition-state theory with multidimensional tunneling (MS-CVT/MT) is used to study the kinetics for hydrolysis of N₂O₅ by a single water molecule, whose rate constant can be summarized by the Arrhenius expression 9.51 × 10^–17 (<i>T</i>/298 K)^3.354 e^{(−7900K/<i>T</i>)} cm³ molecule^–1 s^–1 over the temperature range 180–1800 K

Tangibles in the Balance: a Discovery Learning Task with Physical or Graphical Materials

An assumption behind much work on the use of tangibles for learning is that there are individual cognitive benefits related to the physical manipulation of materials However, previous work that has shown learning benefits in using physical materials often hasn't adequately controlled for the covariates of physicality. In this paper, we describe a study where we compared the effects on adults' discovery learning on a balance beam task of using either physical or graphical materials and with either control or no control over the design of experiments No effects were found of either the type of learning material or the level of control over the experimental design

RHIS_benthic_FINAL

Community-level bleaching impact dat

Thermodynamic and Energetic Effects on the Diameter and Defect Density in Single-Walled Carbon Nanotube Synthesis

Single-walled carbon nanotube (SWCNT) ensembles are characterized by their defect density and diameter distribution. Here, SWCNTs are grown using chemical vapor deposition with acetylene as the carbon source and cobalt as the catalyst and analyzed ex situ, without any modification or processing, using Raman spectroscopy. The defect density shows an activated temperature dependence (activation energy ∼0.8 eV or ∼80 kJ/mol) with fewer defects at high growth temperatures for a wide range of experimental parameters. This is consistent with a single activated mechanism, such as the catalytic healing of defects, possibly a single simple defect. Consistent with previous reports, we see that low growth temperatures produce smaller diameter SWCNTs than high growth temperatures. Elementary thermodynamic considerations of the strain energy in the lattice constrain the SWCNT diameter distribution and its temperature dependence and appear consistent with our observations. A “phase diagram” for SWCNT growth is constructed and suggests methods of controlling the diameter distribution. There is a trade-off here between small diameter SWCNTs and SWCNTs with low defect densities

Glyoxal Oxidation Mechanism: Implications for the Reactions HCO + O₂ and OCHCHO + HO₂

A detailed mechanism for the thermal decomposition and oxidation of the flame intermediate glyoxal (OCHCHO) has been assembled from available theoretical and experimental literature data. The modeling capabilities of this extensive mechanism have been tested by simulating experimental HCO profiles measured at intermediate and high temperatures in previous glyoxal photolysis and pyrolysis studies. Additionally, new experiments on glyoxal pyrolysis and oxidation have been performed with glyoxal and glyoxal/oxygen mixtures in Ar behind shock waves at temperatures of 1285–1760 K at two different total density ranges. HCO concentration–time profiles have been detected by frequency modulation spectroscopy at a wavelength of λ = 614.752 nm. The temperature range of available direct rate constant data of the high-temperature key reaction HCO + O₂ → CO + HO₂ has been extended up to 1705 K and confirms a temperature dependence consistent with a dominating direct abstraction channel. Taking into account available literature data obtained at lower temperatures, the following rate constant expression is recommended over the temperature range 295 K < <i>T</i> < 1705 K: <i>k</i>₁/(cm³ mol^–1 s^–1) = 6.92 × 10⁶ × <i>T</i>^1.90 × exp­(+5.73 kJ/mol/<i>RT</i>). At intermediate temperatures, the reaction OCHCHO + HO₂ becomes more important. A detailed reanalysis of previous experimental data as well as more recent theoretical predictions favor the formation of a recombination product in contrast to the formerly assumed dominating and fast OH-forming channel. Modeling results of the present study support the formation of HOCH­(OO)­CHO and provide a 2 orders of magnitude lower rate constant estimate for the OH channel. Hence, low-temperature generation of chain carriers has to be attributed to secondary reactions of HOCH­(OO)­CHO

bleaching_data_FINAL

species-specific bleaching dat

Additional file 1: of Anticipatory and compensatory postural adjustments in people with low back pain: a protocol for a systematic review and meta-analysis

PRISMA-P (Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols) checklist. Recommended items to address in a systematic review protocol

Additional file 3: of Factors contributing to chronic ankle instability: a protocol for a systematic review of systematic reviews

Modified R-AMSTAR checklist—quality assessment for systematic reviews of observational studies (adapted from R-AMSTAR). Modified R-AMSTAR tool used to appraise the quality of each systematic review. (PDF 195 kb

Effectivenessof Pilates exercise versus usual care and physical activity in reducing pain in people with chronic low back pain.

a<p>statistically significant between group difference;</p>+<p>reported as statistically significant in study, but not calculated in this review;</p>s<p>with or without usual care.</p