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Experimental and computational studies of ruthenium complexes bearing Z-acceptor aluminum-based phosphine pincer ligands
Get PDFFunding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 792674 (FMM) and EPSRC (DTP studentships to C.J.I. and A.L.B.).Reaction of [Ru(C6H4PPh2)2(Ph2PC6H4AlMe(THF))H] with CO results in clean conversion to the Ru−Al heterobimetallic complex [Ru(AlMePhos)(CO)3] ( 1 ), where AlMePhos is the novel P–Al(Me)–P pincer ligand (o-Ph2PC6H4)2AlMe. Under photolytic conditions, 1 reacts with H2 to give [Ru(AlMePhos)(CO)2(μ-H)H] ( 2 ) that is characterized by multinuclear NMR and IR spectroscopies. DFT calculations indicate that 2 features one terminal and one bridging hydride that are respectively anti and syn to the AlMe group. Calculations also define a mechanism for H2 addition to 1 and predict facile hydride exchange in 2 that is also observed experimentally. Reaction of 1 with B(C6F5)3 results in Me abstraction to form the ion pair [Ru(AlPhos)(CO)3][MeB(C6F5)3] ( 4 ) featuring a cationic [(o-Ph2PC6H4)2Al]+ ligand, [AlPhos]+. The Ru–Al distance in 4 (2.5334(16) Å) is significantly shorter than that in 1 (2.6578(6) Å), consistent with an enhanced Lewis acidity of the [AlPhos]+ ligand. This is corroborated by a blue shift in both the observed and computed νCO stretching frequencies upon Me abstraction. Electronic structure analyses (QTAIM and EDA-ETS) comparing 1 , 4 , and the previously reported [Ru(ZnPhos)(CO)3] analogue (ZnPhos = (o-Ph2PC6H4)2Zn) indicate that the Lewis acidity of these pincer ligands increases along the series ZnPhos < AlMePhos < [AlPhos]+.Peer reviewe
British Cardiovascular Intervention Society consensus position statement on out-of-hospital cardiac arrest 2 : post-discharge rehabilitation
Get PDFFunding: This work was partly funded by a King’s College Hospital R & D Grant and was supported by the Department of Health through a National Institute for Health Research Biomedical Research Centre award to Guy’s & St Thomas’ NHS Foundation Trust in partnership with King’s College London and King’s College Hospital NHS Foundation Trust, UK.Out-of-hospital cardiac arrest (OHCA) is a major public health issue that poses significant challenges both in immediate management and long-term follow-up. Survivors of OHCA often experience a combination of complex medical, physical and psychological needs that have a significant impact on quality of life. Guidelines suggest a multi-dimensional follow-up to address both physical and non-physical domains for survivors. However, it is likely that there is substantial unwarranted variation in provision of services throughout the UK. Currently, there is no nationally agreed model for the follow-up of OHCA survivors and there is an urgent need for a set of standards and guidelines in order to ensure equal access for all. Accordingly, the British Cardiovascular Interventional Society established a multi-disciplinary working group to develop a position statement that summarises the most up-to-date evidence and provides guidance on essential and desirable services for a dedicated follow-up pathway for survivors of OHCA.Peer reviewe
POLG mutations lead to abnormal mitochondrial remodeling during neural differentiation of human pluripotent stem cells via SIRT3/AMPK pathway inhibition
Get PDFFunding: This work was supported by funding from the Norwegian Research Council (project number: 229652), Rakel og Otto Kr.Bruuns legat. G.J.S was partly supported by the Norwegian Research Council through its Centres of Excellence funding scheme (project number: 262613). A.C was supported by the Chinese Government Funding: Department of Science & Technology of Shandong Province (project number: ZR2019ZD33 and 2020CXGC010903), the Special Foundation for Taishan Scholars (project number: ts20110814), Jinan Microecological Biomedicine Shandong Laboratory (project number: JNL-2022003A) and the China Scholarship Council (project number: the China scholarship council 201906220275). J.W was supported by the Special Foundation for Taishan Scholars (project number: ts20110814 and tshw201502056).We showed previously that POLG mutations cause major changes in mitochondrial function, including loss of mitochondrial respiratory chain (MRC) complex I, mitochondrial DNA (mtDNA) depletion and an abnormal NAD+/NADH ratio in both neural stem cells (NSCs) and astrocytes differentiated from induced pluripotent stem cells (iPSCs). In the current study, we looked at mitochondrial remodeling as stem cells transit pluripotency and during differentiation from NSCs to both dopaminergic (DA) neurons and astrocytes comparing the process in POLG-mutated and control stem cells. We saw that mitochondrial membrane potential (MMP), mitochondrial volume, ATP production and reactive oxygen species (ROS) changed in similar ways in POLG and control NSCs, but mtDNA replication, MRC complex I and NAD+ metabolism failed to remodel normally. In DA neurons differentiated from NSCs, we saw that POLG mutations caused failure to increase MMP and ATP production and blunted the increase in mtDNA and complex I. Interestingly, mitochondrial remodeling during astrocyte differentiation from NSCs was similar in both POLG-mutated and control NSCs. Further, we showed downregulation of the SIRT3/AMPK pathways in POLG-mutated cells, suggesting that POLG mutations lead to abnormal mitochondrial remodeling in early neural development due to the downregulation of these pathways.Peer reviewe
Inverse isotope effects in single-crystal to single-crystal reactivity and the isolation of a rhodium cyclooctane σ-alkane complex
Get PDFFunding: EPSRC (EP/M024210/2) and SCG chemicals provided funding.The sequential solid/gas single-crystal to single-crystal reaction of [Rh(Cy2P(CH2)3PCy2)(COD)][BArF4] (COD = cyclooctadiene) with H2 or D2 was followed in situ by solid-state 31P{1H} NMR spectroscopy (SSNMR) and ex situ by solution quenching and GC-MS. This was quantified using a two-step Johnson–Mehl–Avrami–Kologoromov (JMAK) model that revealed an inverse isotope effect for the second addition of H2, that forms a σ-alkane complex [Rh(Cy2P(CH2)3PCy2)(COA)][BArF4]. Using D2, a temporal window is determined in which a structural solution for this σ-alkane complex is possible, which reveals an η2,η2-binding mode to the Rh(I) center, as supported by periodic density functional theory (DFT) calculations. Extensive H/D exchange occurs during the addition of D2, as promoted by the solid-state microenvironment.Peer reviewe
'Mine the volume' : excess and the voluminous ecological politics of capitalist frontiers
Get PDFFunding: The authors benefitted from internal funding made available through the St Andrews Interdisciplinary Research Support Fund.Mining frontiers are moving ever further beyond Earth's surface, as new subterranean realms, the seafloor, the atmosphere and outer space increasingly come into the purview of entrepreneurial activity. In this paper, we deploy an environmental governmentality analytic to examine mining as a site-specific, intervening activity that brings the relationship between these different material spaces into view. We recognise that as mining expands through technological advancement ever further beyond its previous terrestrial foundations, it builds on and deepens colonial environmental governance strategies. We argue that as it does so, efforts to govern mining are likely to be increasingly challenged by its ‘excess’, by which we mean the matter that surpasses surficial enclosures and goes on to produce unintended physical and social consequences for other spaces and places. We construct our argument by examining secondary data on mining at three resource frontiers at varying stages of exploitation and associated governance: (i) surface mining during European colonialisation of the Amazon Basin; (ii) ongoing preparations for deep-sea mining in the Clarion-Clipperton Fracture Zone of the Pacific Ocean; and (iii) the prospect of asteroid mining in outer space. Overall, the paper draws attention to the overlapping nature of the planet's voluminous, material spaces and its ability to frustrate environmental governance efforts. It offers a voluminous analysis across material spaces to burgeoning debates within political ecology.Peer reviewe
Magnetic field morphology and evolution in the Central Molecular Zone and its effect on gas dynamics
No full textFunding: M.C.S. acknowledges financial support from the European Research Council under the ERC Starting Grant “GalFlow” (grant 101116226) and from the Royal Society (URF\R1\221118). J.D.H. gratefully acknowledges financial support from the Royal Society (University Research Fellowship; URF/R1/221620). A.S.M. acknowledges support from the RyC2021-032892-I grant funded by MCIN/AEI/10.13039/501100011033 and by the European Union ‘Next GenerationEU’/PRTR, as well as the program Unidad de Excelencia María de Maeztu CEX2020-001058. UE. R.S.K., S.C.O.G. and P.G. gratefully acknowledge support from the ERC via the ERC Synergy Grant “ECOGAL” (grant 855130). E.S. acknowledges support from the Marie Skłodowska-Curie Grant 101061217. J.M.D.K. gratefully acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme via the ERC Starting Grant MUSTANG (grant agreement number 714907). J.G. is a member of the International Max Planck Research School for Astronomy and Cosmic Physics at the University of Heidelberg (IMPRS-HD) and acknowledges financial support by the European Research Council via the ERC Synergy Grant “ECOGAL” (project ID 855130).The interstellar medium in the Milky Way’s Central Molecular Zone (CMZ) is known to be strongly magnetised, but its large-scale morphology and impact on the gas dynamics are not well understood. We explore the impact and properties of magnetic fields in the CMZ using three-dimensional non-self gravitating magnetohydrodynamical simulations of gas flow in an external Milky Way barred potential. We find that: (1) The magnetic field is conveniently decomposed into a regular time-averaged component and an irregular turbulent component. The regular component aligns well with the velocity vectors of the gas everywhere, including within the bar lanes. (2) The field geometry transitions from parallel to the Galactic plane near ɀ = 0 to poloidal away from the plane. (3) The magneto-rotational instability (MRI) causes an in-plane inflow of matter from the CMZ gas ring towards the central few parsecs of 0.01−0.1 M⊙ yr−1 that is absent in the unmagnetised simulations. However, the magnetic fields have no significant effect on the larger-scale bar-driven inflow that brings the gas from the Galactic disc into the CMZ. (4) A combination of bar inflow and MRI-driven turbulence can sustain a turbulent vertical velocity dispersion of σɀ = 5 km s−1 on scales of 20 pc in the CMZ ring. The MRI alone sustains a velocity dispersion of σɀ ≃ 3 km s−1. Both these numbers are lower than the observed velocity dispersion of gas in the CMZ, suggesting that other processes such as stellar feedback are necessary to explain the observations. (5) Dynamo action driven by differential rotation and the MRI amplifies the magnetic fields in the CMZ ring until they saturate at a value that scales with the average local density as B ≃ 102 (n/103 cm−3)0.33 µG. Finally, we discuss the implications of our results within the observational context in the CMZ.Peer reviewe
Kinetic tomography of the Galactic plane within 1.25 kiloparsecs from the Sun. The interstellar flows revealed by HI and CO line emission and 3D dust
Get PDFFunding: This project was funded by the European Research Council via the ERC Synergy Grant “ECOGAL” (project ID 855130).We present a reconstruction of the line-of-sight motions of the local interstellar medium (ISM) based on the combination of a model of the three-dimensional dust density distribution within 1.25 kpc from the Sun and the H I and CO line emission within Galactic latitudes |b| ≤ 5°. We used the histogram of oriented gradient (HOG) method, a computer vision technique for evaluating the morphological correlation between images, to match the plane-of-the-sky dust distribution across distances with the atomic and molecular line emission. We identified a significant correlation between the 3D dust model and the line emission. We employed this correlation to assign line-of-sight velocities to the dust across density channels and produce a face-on map of the local ISM radial motions with respect to the local standard of rest (LSR). We find that most of the material in the 3D dust model follows the large-scale pattern of Galactic rotation; however, we also report local departures from the rotation pattern with standard deviations of 10.8 and 6.6 km s−1 for the H I and CO line emission, respectively. The mean kinetic energy densities corresponding to these streaming motions are around 0.11 and 0.04 eV/cm3 from either gas tracer. Assuming homogeneity and isotropy in the velocity field, these values are within a factor of a few of the total kinetic energy density. These kinetic energy values are roughly comparable to other energy densities, thus confirming the near-equipartition in the local ISM. Yet, we identify energy and momentum overdensities of around a factor of ten concentrated in the Radcliffe Wave, the Split, and other local density structures. Although we do not find evidence of the local spiral arm’s impact on these energy overdensities, their distribution suggests the influence of large-scale effects that, in addition to supernova feedback, shape the energy distribution and dynamics in the solar neighborhood.Peer reviewe
Speciation of VOC emissions related to offshore North Sea oil and gas production
Get PDFFunding: Airborne data were obtained using the BAe-146-301 Atmospheric Research Aircraft (ARA) flown by Airtask Ltd. and managed by FAAM Airborne Laboratory, jointly operated by UK Research and Innovation (UKRI) and the University of Leeds, and a DCH6 Twin Otter operated by the British Antarctic Survey (BAS). The FAAM aircraft data were collected as part of the Demonstration Of A Comprehensive Approach To Monitoring Emissions From Oil and Gas Installations (AEOG) project, the Improved understanding of accidental releases from oil and gas industries offshore project, and the Methane Observations and Yearly Assessments (MOYA) project, all funded by the Natural Environment Research Council (NERC). The Twin Otter aircraft campaigns were funded under the Climate and Clean Air Coalition (CCAC) Oil and Gas Methane Science Studies (MSS), hosted by the United Nations Environment Programme. Funding was provided by the Environmental Defense Fund, Oil and Gas Climate Initiative, European Commission, and CCAC. We also acknowledge the Offshore Petroleum Regulator for Environment and Decommissioning (OPRED) and Ricardo Energy & Environment for their involvement as project partners on the AEOG project.The North Sea is Europe's key oil and gas (O&G) basin with the output currently meeting 3 %–4 % of global oil supply. Despite this, there are few observational constraints on the nature of atmospheric emissions from this region, with most information derived from bottom-up inventory estimates. This study reports on airborne measurements of volatile organic compounds (VOCs) emitted from O&G-producing regions in the North Sea. VOC source emission signatures for the primary extraction products from offshore fields (oil, gas, condensate, mixed) were determined in four geographic regions. Measured iso-pentane to n-pentane (iC5 / nC5) ratios were 0.89–1.24 for all regions, used as a confirmatory indicator of O&G activities. Light alkanes (ethane, propane, butane, pentane) were the dominant species emitted in all four regions; however, total OH reactivity was dominated by unsaturated species, such as 1,3-butadiene, despite their relatively low abundance. Benzene to toluene ratios indicated the influence of possible terrestrial combustion sources of emissions in the southern, gas-producing region of the North Sea, seen only during south or south-westerly wind episodes. However, all other regions showed a characteristic signature of O&G operations. Correlations between ethane (C2H6) and methane (CH4) confirmed O&G production to be the primary CH4 source. The enhancement ratio (ΔC2H6 / ΔCH4) ranged between 0.03–0.18, indicating a spatial dependence on emissions with both wet and dry CH4 emission sources. The excess mole fraction demonstrated that deepwater oil extraction resulted in a greater proportion of emissions of higher carbon number alkanes relative to CH4, whereas gas extraction, typically from shallow waters, resulted in a less complex mix of emissions dominated by CH4. The VOC source profiles measured were similar to those in the UK National Atmospheric Emissions Inventory (NAEI) for oil production, with consistency between the molar ratios of light alkanes to propane. The largest discrepancies between observations and the inventory were for mono-aromatic compounds, highlighting that these species are not currently fully captured in the inventory. These results demonstrate the applicability of VOC measurements to distinguish unique sources within the O&G sector and give an overview of VOC speciation over the North Sea.Peer reviewe
Financial sanctions and the dollar : a critical perspective on the impact of financial sanctions on the dollar as the world's key currency
No full textThis portfolio consists of two research articles, a discussion piece, and a commentary paper aimed to answer one fundamental question; to what extent have U.S. economic sanctions effected the key currency role of the dollar? Herein, I have presented each article beginning with the commentary, followed by two research papers, ending with a discussion piece. In the commentary paper, I review existing literature on the topic of sanctions and introduce the exploration of negative externalities, a field that is underexplored. The commentary also includes a review and summaries of the other articles in the portfolio followed by an overview and discussion of a wider scope than the articles themselves, to provide additional context, discussion, and conclusions. In one article, Establishment of non-dollar financial plumbing, I use a case study design to examine how oil producing targets of sanctions regimes and their export customers respond within a framework of currency competition in the energy trading market. In another article, Sovereign Europe and the euro, my research focuses on secondary sanctions and the reactions of an important ally as they relate to the dollar, the world’s reserve currency, using a similar research design. In the discussion paper, I approach sanctions broadly, and explore potential implications for emerging financial technology for the dollar and the efficacy of sanctions themselves. Overall, my findings show that the use of financial sanctions by the United States, enabled by a weaponized dollar, has led to significant backlash among rivals and allies alike, and that this backlash may be leading to an environment of increased competition for the dollar as an international currency. As a result, the efficacy of sanctions themselves comes into question as successful adaptations and countermeasures are developed
Isothiourea-catalysed enantioselective synthesis of phosphonate-functionalised β-lactones
No full textFunding: The research leading to these results has received funding from AstraZeneca (FMP), the EaSI-CAT Centre for Doctoral Training (FMP), the CSC-St Andrews PhD Scholarship Scheme (YW) and the EPRSC (CMY, EP/S019359/1). ADS thanks the EPRSC Programme Grant “Boron: Beyond the Reagent” (EP/W007517) for support.Despite growing interest in the reactivity and biological activity of phosphonate-containing molecules, the application of α-ketophosphonates in enantioselective formal [2 + 2] cycloadditions to generate β-lactones bearing a pendant phosphonate group remains unreported. In this manuscript, a highly diastereo- and enantioselective isothiourea-catalysed formal [2 + 2] cycloaddition of both alkyl- and aryl substituted C(1)-ammonium enolates and α-ketophosphonates is established. This strategy allows a mild, practical and scalable approach to highly enantioenriched C(3)-unsubstituted and C(3)-alkyl β-lactones bearing a phosphonate motif from their corresponding α-silyl acids, via a desilylative pathway (30 examples, up to 98%, >95 : 5 dr, >99 : 1 er). Alternatively, the use of (hetero)arylacetic acids allows the preparation of C(3)-(hetero)aryl β-lactones to be accessed in high yields and stereocontrol (19 examples, up to 98%, >95 : 5 dr, 99 : 1 er).Peer reviewe
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