Angle-Resolved X-Ray Circular and Magnetic Circular Dichroisms: Definitions and Applications

We introduce definitions of angle-resolved x-ray circular dichroism (ARXCD) and magnetic x-ray circular dichroism (ARMXCD). As defined, the much larger effect of circular dichroism (ARXCD) is separated from the smaller magnetic (ARMXCD) effect. In all materials, ARXCD is zero along mirror planes while nonzero elsewhere. ARMXCD is nonzero only in magnetic materials. The measurement and analysis of ARMXCD allow element specific surface magnetism and surface structure as well as their inter-relationship to be studied as functions of the outgoing electron\u27s direction

Gabapentin, a human therapeutic medication and an environmental substance transferring at trace levels to horses: a case report.

Gabapentin, 1-(Aminomethyl)cyclohexaneacetic acid, MW 171.240, is a frequently prescribed high dose human medication that is also used recreationally. Gabapentin is orally absorbed; the dose can be 3,000 mg/day and it is excreted essentially unchanged in urine. Gabapentin is stable in the environment and routinely detected in urban wastewater. Gabapentin randomly transfers from humans to racing horses and is at times detected at pharmacologically ineffective / trace level concentrations in equine plasma and urine. In Ohio racing between January 2019 and July 2020,18 Gabapentin identifications, all less than 2 ng/ml in plasma, were reported. These identifications were ongoing because the horsemen involved were unable to pin down and therefore avoid the source of these identifications. Given that 44 ng/ml or less is an Irrelevant Plasma Concentration (IPC) of Gabapentin in horses, we proposed a 5 ng/ml plasma interim Screening Limit of Detection for Gabapentin identifications in Ohio racing, and an essentially similar 8 ng/ml plasma Screening Limit of Detection was suggested by a scientific advisor to the Ohio Horse Racing Commission. As such, an analytical Screening Limit of 8 ng /ml in plasma is an appropriate and pharmacologically conservative analytical cut-off or Screening Limit of Detection (SLOD) for Gabapentin in equine competitive events to avoid the calling of positive identifications on random unavoidable trace level identifications of this widely prescribed human therapeutic medication in equine forensic samples

Sporadic Worldwide “Clusters” of Feed Driven Zilpaterol Identifications in Racing Horses: A Review and Analysis

Zilpaterol is a β2-adrenergic agonist medication approved in certain countries as a cattle feed additive to improve carcass quality. Trace amounts of Zilpaterol can transfer to horse feed, yielding equine urinary “identifications” of Zilpaterol. These “identifications” occur because Zilpaterol is highly bioavailable in horses, resistant to biotransformation and excreted as unchanged Zilpaterol in urine, where it has a 5 day or so terminal half-life. In horses, urinary steady-state concentrations are reached 25 days (5 half-lives) after exposure to contaminated feed. Zilpaterol readily presents in horse urine, yielding clusters of feed related Zilpaterol identifications in racehorses. The first cluster, April 2013, involved 48 racehorses in California; the second cluster, July 2013, involved 15 to 80 racehorses in Hong Kong. The third cluster, March 2019, involved 24 racehorses in Mauritius; this cluster traced to South African feedstuffs, triggering an alert concerning possible Zilpaterol feed contamination in South African racing. The fourth cluster, September/October 2020 involved 18 or so identifications in French racing, reported by the French Laboratories des Courses Hippiques, (LCH), and in July 2021, a fifth cluster of 10 Zilpaterol identifications in South Africa. The regulatory approach to these identifications has been to alert horsemen and feed companies and penalties against horsemen are generally not implemented. Additionally, given their minimal exposure to Zilpaterol, there is little likelihood of Zilpaterol effects on racing performance or adverse health effects for exposed horses. The driving factor in these events is that Zilpaterol is dissolved in molasses for incorporation into cattle feed. Inadvertent incorporation of Zilpaterol containing molasses into horse feed was the source of the California and Hong Kong Zilpaterol identifications. A second factor in the 2019 Mauritius and 2020 French identifications was the sensitivity of testing for Zilpaterol in Mauritius and France, with the French laboratory reportedly testing at a “more sensitive level for Zilpaterol”. As of January 1st, 2021, the new FEI Atypical Finding (ATF) policy specifies Zilpaterol as a substance to be treated as an Atypical Finding (ATF), allowing consideration of inadvertent feed contamination in the regulatory evaluation of Zilpaterol identifications

The art of earth-building: placing relief models in the culture of modern geography in Britain

This article explores the overlooked history and significance of physical relief models in the development of geographical knowledge and education. By examining their use in academic, educational and public settings, it argues for a broader appreciation of these models as integral to the discipline's material culture. Historical debates around their function and purpose are highlighted amidst developments in modelling techniques, materials, and instructional guides. A deeper investigation into the models, their creators, and their influence on geographical learning and public engagement is advocated for and illustrated through the production and impact of the 1951 book The Earth's Crust

Aminorex Identified in Horse Urine Following Consumption of \u3cem\u3eBarbarea vulgaris\u3c/em\u3e; a Preliminary Report

Background: Aminorex, (RS)-5- Phenyl-4,5-dihydro-1,3-oxazol-2-amine, is an amphetamine-like anorectic and in the United States a Drug Enforcement Administration [DEA] Schedule 1 controlled substance. Aminorex in horse urine is usually present as a metabolite of Levamisole, an equine anthelmintic and immune stimulant. Recently, Aminorex identifications have been reported in horse urine with no history or evidence of Levamisole administration. Analysis of the urine samples suggested a botanical source, directing attention to the Brassicaceae plant family, with their contained GlucoBarbarin and Barbarin as possible sources of Aminorex. Since horsepersons face up to a 1 year suspension and a $10,000.00 fine for an Aminorex identification, the existence of natural sources of Aminorex precursors in equine feedstuffs is of importance to both individual horsepersons and the industry worldwide. Results: Testing the hypothesis that Brassicaceae plants could give rise to Aminorex identifications in equine urine we botanically identified and harvested flowering Kentucky Barbarea vulgaris, (“Yellow Rocket”) in May 2018 in Kentucky and administered the plant orally to two horses. Analysis of post-administration urine samples yielded Aminorex, showing that consumption of Kentucky Barbarea vulgaris can give rise to Aminorex identifications in equine urine. Conclusions: Aminorex has been identified in post administration urine samples from horses fed freshly harvested flowering Kentucky Barbarea vulgaris, colloquially “Yellow Rocket”. These identifications are consistent with occasional low concentration identifications of Aminorex in equine samples submitted for drug testing. The source of these Aminorex identifications is believed to be the chemically related Barbarin, found as its precursor GlucoBarbarin in Kentucky Barbarea vulgaris and related Brassicaceae plants worldwide

Comparison of Branching Ratio and Sum-Rule Analyses of Magnetic Circular Dichroism in X-Ray-Absorption Spectroscopy

Two localized picture methods of analyzing the magnetic circular dichroism in x-ray absorption will be applied to experimental results: the branching ratio (BR) and sum rule (SR) approaches. A derivation of the BR formulas and detailed comparison to the SR expressions will be made, including error estimations. The BR approach will be seen to be a limiting case form of the SR spin-moment expression and provide a simple picture of the underlying physics in magnetic x-ray circular dichroism absorption in 3d magnetic materials

Observation of Strong Resonant Behavior in the Inverse Photoelectron Spectroscopy of Ce Oxide

X-ray emission spectroscopy and resonant inverse photoelectron spectroscopy (RIPES) have been used to investigate the photon emission associated with the Ce 3d5/2 and Ce 3d3/2 thresholds. Strong resonant behavior has been observed in the RIPES of a Ce oxide near the 5/2 and 3/2 edges

Evidence of Dynamical Spin Shielding in Ce from Spin-Resolved Photoelectron Spectroscopy

Using Fano effect measurements upon polycrystalline Ce, we have observed a phase reversal between the spectral structure at the Fermi edge and the other 4f derived feature near a binding energy of 2 eV. The Fano effect is the observation of spin polarized photoelectron emission from nonmagnetic materials, under chirally selective excitation, such as circularly polarized photons. The observation of phase reversal between the two peaks is a direct experimental proof of Kondo shielding in Ce, confirming the predictions of Gunnarsson and Shoenhammer, albeit with a small modification