Rhapso : automatic stitching of mass segments from fourier transform ion cyclotron resonance mass spectra

Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) provides the resolution and mass accuracy needed to analyze complex mixtures such as crude oil. When mixtures contain many different components, a competitive effect within the ICR cell takes place that hampers the detection of a potentially large fraction of the components. Recently, a new data collection technique, which consists of acquiring several spectra of small mass ranges and assembling a complete spectrum afterward, enabled the observation of a record number of peaks with greater accuracy compared to broadband methods. There is a need for statistical methods to combine and preprocess segmented acquisition data. A particular challenge of quadrupole isolation is that near the window edges there is a drop in intensity, hampering the stitching of consecutive windows. We developed an algorithm called Rhapso to stitch peak lists corresponding to multiple different m/z regions from crude oil samples. Rhapso corrects potential edge effects to enable the use of smaller windows and reduce the required overlap between windows, corrects mass shifts between windows, and generates a single peak list for the full spectrum. Relative to a stitching performed manually, Rhapso increased the data processing speed and avoided potential human errors, simplifying the subsequent chemical analysis of the sample. Relative to a broadband spectrum, the stitched output showed an over 2-fold increase in assigned peaks and reduced mass error by a factor of 2. Rhapso is expected to enable routine use of this spectral stitching method for ultracomplex samples, giving a more detailed characterization of existing samples and enabling the characterization of samples that were previously too complex to analyze

Qualitative Analysis of Universes with Varying Alpha

Assuming a Friedmann universe which evolves with a power-law scale factor, $a=t^{n}$, we analyse the phase space of the system of equations that describes a time-varying fine structure 'constant', $\alpha$, in the Bekenstein-Sandvik-Barrow-Magueijo generalisation of general relativity. We have classified all the possible behaviours of $\alpha (t)$ in ever-expanding universes with different $n$ and find new exact solutions for $\alpha (t)$. We find the attractors points in the phase space for all $n$. In general, $\alpha$ will be a non-decreasing function of time that increases logarithmically in time during a period when the expansion is dust dominated ($n=2/3$), but becomes constant when $n>2/3$. This includes the case of negative-curvature domination ($n=1$). $\alpha$ also tends rapidly to a constant when the expansion scale factor increases exponentially. A general set of conditions is established for $\alpha$ to become asymptotically constant at late times in an expanding universe.Comment: 26 pages, 6 figure

New Spectroscopic Insight into the Deactivation of a ZSM-5 Methanol-to-Hydrocarbons Catalyst

Funding Information: Johnson Matthey plc. is thanked for supplying the ZSM‐5 zeolite and for financial support through the provision of industrial CASE studentships in partnership with the EPSRC (APH (EP/P510506/1), AZ (EP/N509176/1)). Experiments at the ISIS Neutron and Muon Source were made possible by a beam time allocation from the Science and Technologies Facilities Council. The resources and support provided by the UK Catalysis Hub membership of the UK Catalysis Hub consortium and funded by EPSRC grants EP/R026815/1 and EP/R026939/1 are gratefully acknowledged. This research has been performed with the use of facilities and equipment at the Research Complex at Harwell; the authors are grateful to the Research Complex for this access and support. Dr Andrea Sauerwein and Dr Jonathan Bradley (Johnson Matthey) are thanked for their help in acquiring the Si and Al NMR spectra using the Bruker Avance Neo spectrometer.Peer reviewedPublisher PD

Counting the Acid Sites in a Commercial ZSM-5 Zeolite Catalyst

This work was funded by Johnson Matthey plc. through the provision of industrial CASE studentships in partnership with the EPSRC (AZ (EP/N509176/1), APH (EP/P510506/1)). Experiments at the ISIS Neutron and Muon Source were made possible by beam time allocations from the Science and Technologies Facilities Council.45,46 Resources and support were provided by the UK Catalysis Hub via membership of the UK Catalysis Hub consortium and funded by EPSRC grants EP/R026815/1 and EP/R026939/1Peer reviewedPublisher PD

On the transition to Gasoline-to-Olefins chemistry in the cracking reactions of 1-octene over H-ZSM-5 catalysts

The cracking reactions of 1-octene over H-ZSM-5 zeolite are studied via micro-reactor and off-line spectroscopic techniques over a period of up to 72 hours on stream and a temperature range of 473 – 673 K. 1-Octene is found to react via a two-cycle hydrocarbon pool mechanism, with strong similarities to that reported for methanol-to-hydrocarbons chemistry. This dual-cycle mechanism requires temperatures of 673 K or higher to function with full efficiency, with lower temperatures deactivating portions of the cyclic mechanism, leading to premature deactivation of the catalyst through over-production of coke species. Inelastic neutron scattering is used to study the coke composition, identifying two distinct deactivation mechanisms depending on reaction temperature. The catalyst is also found to slowly progress from an aromatic-heavy to an olefin-heavy product regime even at full efficiency due to progressive blockage of active sites by amorphous carbon-rich coke. Artificial aging of the zeolite, through steam treatment, is found to shift the catalyst lifetime so that it commences at a later stage in this process, resulting in increased light olefin production. The reduced aromatic production also means that deactivation of the catalyst occurs more slowly in steamed catalysts than in fresh ones, after an equivalent time-on-stream. Collectively, these observations connect with the application of ZSM-5 catalysts to facilitate gasoline-to-olefins chemistry in fluidized catalytic cracking unit operations

Constraints on Cosmic Strings due to Black Holes Formed from Collapsed Cosmic String Loops

The cosmological features of primordial black holes formed from collapsed cosmic string loops are studied. Observational restrictions on a population of primordial black holes are used to restrict $f$, the fraction of cosmic string loops which collapse to form black holes, and $\mu$, the cosmic string mass-per-unit-length. Using a realistic model of cosmic strings, we find the strongest restriction on the parameters $f$ and $\mu$ is due to the energy density in $100 MeV$ photons radiated by the black holes. We also find that inert black hole remnants cannot serve as the dark matter. If earlier, crude estimates of $f$ are reliable, our results severely restrict $\mu$, and therefore limit the viability of the cosmic string large-scale structure scenario.Comment: (Plain Tex, uses tables.tex -- wrapped lines corrected), 11 pages, FERMILAB-Pub-93/137-

An Analysis of Private School Closings

We add to the small literature on private school supply by exploring exits of K-12 private schools. We find that the closure of private schools is not an infrequent event, and use national survey data from the National Center for Education Statistics to study closures of private schools. We assume that the probability of an exit is a function of excess supply of private schools over the demand, as well as the school's characteristics such as age, size, and religious affiliation. Our empirical results generally support the implications of the model. Working Paper 07-0

Interplay Between Gravity and Quintessence: A Set of New GR Solutions

A set of new exact analytical General Relativity (GR) solutions with time-dependent and spatially inhomogeneous quintessence demonstrate 1) a static non-empty space-time with a horizon-type singular surface; 2) time-dependent spatially homogeneous `spheres' which are completely different in geometry from the Friedmann isotropic models; 3) infinitely strong anti-gravity at a `true' singularity where the density is infinitely large. It is also found that 4) the GR solutions allow for an extreme `density-free' form of energy that can generate regular space-time geometries

US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report

This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017.Comment: 102 pages + reference

Our friend in the north: the origins, evolution and appeal of the cult of St Duthac of Tain in later Middle Ages

St Duthac of Tain was one of the most popular Scottish saints of the later middle ages. From the late fourteenth century until the reformation devotion to Duthac outstripped that of Andrew, Columba, Margaret and Mungo, and Duthac's shrine in Easter Ross became a regular haunt of James IV (1488-1513) and James V (1513-42). Hitherto historians have tacitly accepted the view of David McRoberts that Duthac was one of several local saints whose emergence and popularity in the fifteenth century was part of a wider self-consciously nationalist trend in Scottish religious practice. This study looks beyond the paradigm of nationalism to trace and explain the popularity of St Duthac from the shadowy origins of the cult to its heyday in the early sixteenth century