Evidence for partial quenching of orbital angular momentum upon complex formation in the infrared spectrum of OH-acetylene

The entrance channel leading to the addition reaction between the hydroxyl radical and acetylene has been examined by spectroscopic characterization of the asymmetric CH stretching band of the π-hydrogen bonded OH-acetylene reactant complex. The infrared action spectrum observed at 3278.6 cm−1 (origin) consists of seven peaks of various intensities and widths, and is very different from those previously reported for closed-shell HF/HCl-acetylene complexes. The unusual spectrum arises from a partial quenching of the OH orbital angular momentum in the complex, which in turn is caused by a significant splitting of the OH monomer orbital degeneracy into 2A′ and 2A″ electronic states. The magnitude of the 2A′−2A″ splitting as well as the A rotational constant for the OH-acetylene complex are determined from the analysis of this b-type infrared band. The most populated OH product rotational state, jOH = 9/2, is consistent with intramolecular vibrational energy transfer to the ν2 C≡C stretching mode of the departing acetylene fragment. The lifting of the OH orbital degeneracy and partial quenching of its electronic orbital angular momentum indicate that the electronic changes accompanying the evolution of reactants into products have begun to occur in the reactant complex

Infrared spectrum and stability of a π-type hydrogen-bonded complex between the OH and C2H2 reactants

A hydrogen-bonded complex between the hydroxyl radical and acetylene has been stabilized in the reactant channel well leading to the addition reaction and characterized by infrared action spectroscopy in the OH overtone region. Analysis of the rotational band structure associated with the a-type transition observed at 6885.53(1) cm−1 (origin) reveals a T-shaped structure with a 3.327(5) Å separation between the centers of mass of the monomer constituents. The OH (v = 1) product states populated following vibrational predissociation show that dissociation proceeds by two mechanisms: intramolecular vibrational to rotational energy transfer and intermolecular vibrational energy transfer. The highest observed OH product state establishes an upper limit of 956 cm−1 for the stability of the π-type hydrogen-bonded complex. The experimental results are in good accord with the intermolecular distance and well depth at the T-shaped minimum energy configuration obtained from complementary ab initio calculations, which were carried out at the restricted coupled cluster singles, doubles, noniterative triples level of theory with extrapolation to the complete basis set limit

Special features of RAD Sequencing data:implications for genotyping

Restriction site-associated DNA Sequencing (RAD-Seq) is an economical and efficient method for SNP discovery and genotyping. As with other sequencing-by-synthesis methods, RAD-Seq produces stochastic count data and requires sensitive analysis to develop or genotype markers accurately. We show that there are several sources of bias specific to RAD-Seq that are not explicitly addressed by current genotyping tools, namely restriction fragment bias, restriction site heterozygosity and PCR GC content bias. We explore the performance of existing analysis tools given these biases and discuss approaches to limiting or handling biases in RAD-Seq data. While these biases need to be taken seriously, we believe RAD loci affected by them can be excluded or processed with relative ease in most cases and that most RAD loci will be accurately genotyped by existing tools

Deep Convolutional Neural Networks for Estimating Lens Distortion Parameters

In this paper we present a convolutional neural network (CNN) to predict multiple lens distortion parameters from a single input image. Unlike other methods, our network is suitable to create high resolution output as it directly estimates the parameters from the image which then can be used to rectify even very high resolution input images. As our method it is fully automatic, it is suitable for both casual creatives and professional artists. Our results show that our network accurately predicts the lens distortion parameters of high resolution images and corrects the distortions satisfactory

Influence of Axial Spacing on Spanwise Efficiency of a Transonic Axial Compressor Rotor Stage

This study numerically examined the span-wise efficiency of a transonic compressor stage representative of a modern jet engine. Two simulations of a compressor stage with different axial spacing between blade-rows were studied to determine the influence on the fluid flow. The two spacing are denoted as Close and Far. The time-accurate Reynolds-averaged Navier-Stokes computational algorithm MSU-TURBO with a CMOTT turbulence model was used for both cases. All solutions are three-dimensional and model WG-rotor relative motion through a sliding-mash interface and phase-lagged boundary conditions. At reduced spacings the compressor stage is less efficiency, with the largest difference occurring in the mid-span region. One reason for this trend is the wake from the upstream wake generator does not completely mix with the main passage flow prior to entering the rotor passage with decreased axial gaps. Anthoer major unsteady factor identified that influences the compressor efficiency is the tip clearance flow. In the Far case, the tip vortex did not reach spans below 80%. However, for the Close case, the tip vortex reached to around 40% span. Examining the flow one rotor chord downstream revealed the region between 40% and 60% span to be the main difference between the two axial spacings. Additionally, the rotor tip leakage at the reduced spacing occurs around 30% chord, while the Far casing leakage flow does not appear until 50% chord. The consequence of the early appearance of the tip vortex in the Close case is the greater axial distance that the vortex has to drift to lower spans. The greater strength of the Close spacing leakage flow over the Far case may be another reason the vortex is able to influence the mid-span region. The conclusions reached in this analysis are: the upstream wakes interact with the rotor boundary layer and the tip flow is a major factor at reduced spacings. The purpose of this study was to identify the reasons for efficiency losses, therefore further investigations into the correlation between axial spacing and efficiency loss are needed.Mechanical & Aerospace Engineerin