Raman Optical Activity Using Twisted Photons

Raman optical activity underpins a powerful vibrational spectroscopic technique for obtaining detailed structural information about chiral molecular species. The effect centers on the discriminatory interplay between the handedness of material chirality with that of circularly polarized light. Twisted light possessing an optical orbital angular momentum carries helical phase fronts that screw either clockwise or anticlockwise and, thus, possess a handedness that is completely distinct from the polarization. Here a novel form of Raman optical activity that is sensitive to the handedness of the incident twisted photons through a spin-orbit interaction of light is identified, representing a new chiroptical spectroscopic technique

2D nanosheet molybdenum disulphide (MoS2) modified electrodes explored towards the hydrogen evolution reaction

We explore the use of two-dimensional (2D) MoS2 nanosheets as an electro-catalyst for the Hydrogen Evolution Reaction (HER). Using four commonly employed commercially available carbon based electrode support materials, namely edge plane pyrolytic graphite (EPPG), glassy carbon (GC), boron-doped diamond (BDD) and screen-printed graphite electrodes (SPE), we critically evaluate the reported electro-catalytic performance of unmodified and MoS2 modified electrodes towards the HER. Surprisingly, current literature focuses almost exclusively on the use of GC as an underling support electrode upon which HER materials are immobilised. 2D MoS2 nanosheet modified electrodes are found to exhibit a coverage dependant electrocatalytic effect towards the HER. Modification of the supporting electrode surface with an optimal mass of 2D MoS2 nanosheets results in a lowering of the HER onset potential by ca. 0.33, 0.57, 0.29 and 0.31 V at EPPG, GC, SPE and BDD electrodes compared to their unmodified counterparts respectively. The lowering of the HER onset potential is associated with each supporting electrodes individual electron transfer kinetics/properties. The effect of MoS2 coverage is also explored. We reveal that its ability to catalyse the HER is dependent on the mass deposited until a critical mass of 2D MoS2 nanosheets is achieved, after which its electrocatalytic benefits and/or surface stability curtail. The active surface site density and turn over frequency for the 2D MoS2 nanosheets is determined, characterised and found to be dependent on both the coverage of 2D MoS2 nanosheets and the underlying/supporting substrate. This work is essential for those designing, fabricating and consequently electrochemically testing 2D nanosheet materials for the HER

Motive and form in Lowell Liebermann's four Sonatas for violoncello and piano

This manuscript explores the four sonatas for cello and piano by Lowell Liebermann, and is accompanied by my recording of the works, in collaboration with pianist Kevin Chance. These works were composed between 1978 and 2008, but are not yet part of the standard repertoire. Given the lack of well-known sonatas for cello and piano since the mid-20th century, there is a distinct need to promote high-quality new music of this genre. Not only do Liebermann’s sonatas fill a void, but with more exposure, they would appeal to a majority of performers and listeners alike. In this manuscript, I will focus my analysis on Liebermann’s use of sectional forms and simple motives in the sonatas. I will also explore the marked difference between the atonal first sonata and the tonal, lyrical later ones that reflect a much more mature composer, able to fuse highly sectional forms with his own unique sense of style. As only one recording of the sonatas, featuring cellist Dmitri Atapine and pianist Hyeyeon Park, has been publicly released, our new recording will present the works to a wider audience and will offer a different interpretation based on observations developed in the manuscript. My hope is that, in consequence of this project, these sonatas will become more widely performed and recorded, and will form a significant addition to the cello and piano repertoire. (Published By University of Alabama Libraries

Development of a novel analytical approach combining the quantification of amino acids, organic acids and glucose using HPLC-UV-Vis and HPLC-MS with screening via NMR

A simple, rapid, sensitive and selective procedure based on the combination of HPLC-UV-Vis and HPLC-MS has been developed and single laboratory partially validated for the determination of a set of 13 analytes present in a commercially available IVF medium utilising small sample volumes (20–30 μL). The composition fingerprint of the complex sample obtained by NMR spectroscopy in 11 minutes provided identification based on a screening of the metabolomic profile. HPLC-MS allowed the glucose–sodium adduct to be measured accurately and the working and linear ranges achieved were 0.028–0.389 mmol L−1 with a detection limit of 13 μM. HPLC-UV-Vis allowed accurate concentrations of pyruvic and lactic acids with linear ranges over 0.005–0.1 mmol L−1 with a limit of detection of 28 μM for pyruvic acid to be determined in 8 minutes, while lactic acid presented a linear range over 0.1–2 mmol L−1 with a limit of detection of 1.2 mM possible. The use of HPLC-UV-Vis allowed the chromatographic separation of 8 amino acids (aspartate, glutamate, serine, glycine, asparagine, glutamine, alanine, and proline), the dipeptide alanyl-glutamine and taurine previous to a chemical derivatization, providing a total run time of 40 minutes. The method was partially validated to show a linear range of 0.028–0.280 mmol L−1 with detection limits ranging between 1 and 30 μM. Development of the analytical approach provided determination and quantification of a set of 13 analytes from a very complex sample. Although well established analytical techniques were used here, combinatory methodologies were partially validated for the first time to this purpose. The novelty of the combination of techniques relies on a screening tool and a strategy to the future evaluation and an improved assessment of human embryo viability.M. Gómez-Mingot is grateful to the University of Alicante for a Fellowship and funding from the Ministerio de Educación y Ciencia MEC Spain, project (CTQ2007-62345). Luis A. Alcaraz was financed by the Spanish Ministry of Science and Innovation throughout the Juan de la Cierva program