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Transition metal-free catalytic C−H zincation and alumination
Get PDFFunding: This project has received funding from the European Research Council under the European Union's Horizon 2020 research and innovation program (grant agreement No 769599), the University of Edinburgh and the EPSRC (EP/V03829X and EP/T019867/1).C−H metalation is the most efficient method to prepare aryl–zinc and –aluminium complexes that are ubiquitous nucleophiles. Virtually all C−H metalation routes to form Al/Zn organometallics require stoichiometric, strong Brønsted bases with no base-catalyzed reactions reported. Herein we present a catalytic in amine/ammonium salt (Et3N/[(Et3N)H]+) C−H metalation process to form aryl-zinc and aryl-aluminium complexes. Key to this approach is coupling an endergonic C−H metalation step with a sufficiently exergonic dehydrocoupling step between the ammonium salt by-product of C−H metalation ([(Et3N)H]+) and a Zn−H or Al−Me containing complex. This step, forming H2/MeH, makes the overall cycle exergonic while generating more of the reactive metal electrophile. Mechanistic studies supported by DFT calculations revealed metal-specific dehydrocoupling pathways, with the divergent reactivity due to the different metal valency (which impacts the accessibility of amine-free cationic metal complexes) and steric environment. Notably, dehydrocoupling in the zinc system proceeds through a ligand-mediated pathway involving protonation of the β-diketiminate Cγ position. Given this process is applicable to two disparate metals (Zn and Al), other main group metals and ligand sets are expected to be amenable to this transition metal-free, catalytic C−H metalation.Peer reviewe
Sensitivity of density estimates to off-axis beam pattern assumptions in deep-diving odontocetes
Get PDFFunding: his work was supported by National Environmental Research Council (Grant No. NE/J020176/1), for the project “Monitoring Marine Mammals from Autonomous Underwater Vehicles,” and by the U.S. Navy Living Marine Resources program ACCURATE Project [Office of Naval Research (ONR) Contract No. N3943019C2176). T.A.M. is thankful for partial support by CEAUL [funded by Fundação para a Ciência e a Tecnologia (FCT) Portugal 10.54499/UIDB/00006/2020). P.L.T. was supported by Office of Naval Research Grant Nos. N000142012709 and N000142312065.Density estimation from passive acoustic monitoring requires knowledge of the sound production rates and signal characteristics of animal calls. This study explores the impact of the sound radiation pattern of echolocation clicks on density estimation for two deep-diving species, sperm whales (Physeter macrocephalus) and dense-beaked whales (Mesoplodon densirostris). The likelihood of receiving a click from within the narrow half-power biosonar beam at a randomly positioned receiver is small, and the study demonstrates that the majority of clicks are likely to be detected from outside this main beam. However, the beam pattern, particularly for large angles to the animal's axis, is poorly known for most toothed whales, leading to major uncertainties in the detection probability. Using a simulated cue counting scenario with different beam pattern assumptions (n = 2 for sperm whales, n = 3 for beaked whales) combined with tag-derived movement, orientation, and sound production data, this study demonstrates that uncertainty in the beam pattern can bias density estimates from passive acoustic monitoring, especially in low-noise environments. This effect decreases in noisy environments due to reduced detection of off-axis clicks.Peer reviewe
Solid/gas in crystallo reactivity of an Ir(I) methylidene complex
Get PDFFunding: EPSRC (EP/W015552/1 and EP/W015498/1) and Leverhulme Trust (RPG-2020-184).In crystallo stabilization of known, but solution unstable, methylidene complex [Ir(tBu-PONOP)(═CH2)][BArF4] allows single-crystal to single-crystal solid/gas reactivity associated with the {Ir═CH2} group to be studied. Addition of H2 results in [Ir(tBu-PONOP)(H)2][BArF4]; exposure to CO forms iridium(I) carbonyl [Ir(tBu-PONOP)(CO)][BArF4], and reaction with NH3 gas results in the formation of methylamine complex [(tBu-PONOP)Ir(NH2Me)][BArF4] via an aminocarbene intermediate. Periodic density functional theory and electronic structure analyses confirm the Ir═CH2 bond character but with a very low barrier to rotation around the Ir═CH2 bond. Calculations show that addition of NH3 to the electrophilic alkylidene carbon gives an initial ammonium ylid intermediate. Stepwise N–H and C–H transfers then form the aminocarbene intermediate as a kinetic product from which two successive C–H couplings lead to the more stable methylamine product.Peer reviewe
The representation of surface temperature trends in C3S seasonal forecast systems
Get PDFFunding: M.P., D.J.B., and A.W.: EU Horizon 2020, grant agreement 776613. J.S.: NERC (Grant Number(s): NE/S007164/1) and Met Office. J.F.L.: Met Office Hadley Centre Climate Programme funded through the UK Government Departments, BEIS, and Defra.We assess near-surface temperature and sea surface temperature trends in 8 seasonal forecast systems in the Copernicus Climate Change Service archive, over the common hindcast period (1993–2016). All but one of the systems show a faster warming of the global-mean, relative to observations in both boreal summer and winter seasons. On average, systems warm at 0.21 K/decade and 0.22 K/decade for winter and summer, respectively, compared to 0.17 K/decade and 0.19 K/decade for ERA5. In summer, forecast systems tend to show an excessive warming of the tropical Pacific, tropical Atlantic and southern mid-latitudes, which contributes to the difference in global warming rates compared to observations. In contrast, greater warming in the northern mid-latitudes contributes most to trend differences for winter. The faster warming of models over this period has important implications for seasonal forecasts of future global and regional temperature and suggests further work is required to understand this bias.Peer reviewe
Diving behaviour and physiology of the Korean Haenyeo
Get PDFThere is a long history of breath-hold diving cultures in East Asia, with references in Japanese chronicles as early as the third century BC. Given evidence of genetic adaptations for phenotypes associated with enhanced diving capacity within such populations1, it is likely they hold the most prodigious human diving abilities — abilities that may be akin to semi-aquatic mammals, and even some marine mammals. Yet, a dearth of fine-scale information exists on the combined natural diving behaviour and physiological responses within these diving populations. One such extraordinary population is the all-female Haenyeo. Here, we assess the fine-scale diving behaviours and physiological responses of these women during natural harvest diving. Our results show that Haenyeo divers demonstrate the highest proportions of time underwater of any humans, also exceeding those of semi-aquatic mammals and being comparable with some marine mammals. Additionally, they do not exhibit an overt cardiovascular depression, or ‘dive response’, classically associated with consummate diving mammals.Peer reviewe
Ted Hughes's Tales from Ovid : translation as a poetic dialogue with the Roman poet
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On the onset of filamentation on two-dimensional vorticity interfaces
Get PDFFunding: Adrian Constantin was supported by the Austrian Science Fund (FWF), grant number Z 387-N. Pierre Germain was supported by a Wolfson fellowship from the Royal Society and the Simons collaboration on Wave Turbulence.We study an asymptotic nonlinear model for filamention on two-dimensional vorticity interfaces. Different re-formulations of the model equation reveal its underlying structural properties. They enable us to construct global weak solutions and to prove the existence of traveling waves.Peer reviewe
The clonality window : relatedness and the group covariance effect in the evolution of division of labour
Get PDFFunding: This work was funded by the School of Biology, University of St Andrews (K.Z.T.) and the European Research Council (grant number 771387; A.G.).Cellular division of labor is closely associated with the emergence of organismality in the evolution of obligate multicellularity. Michod has suggested that a trade-off between viability and fecundity may—through a “group covariance effect”—lead to a group’s fitness being augmented above the average of its constituents’ fitnesses, offering a first step toward division of labor and obligate multicellularity. However, it is difficult to see how a group’s fitness could be different from the aggregate of its constituents. Here, we investigate the same fitness trade-off and its consequences for division of labor. We recover the covariance effect, revealing that it is a consequence of cells sharing the products of their labors and clarifying that the group’s fitness remains equal to the aggregate of the fitnesses of its constituent cells. We show that the covariance effect imparts an inclusive-fitness benefit for cells that share, but that—all else being equal—natural selection favors sharing only when groupmates are genetically identical, yielding a “clonality window.” Lastly, we find that sharing is a critical determinant as to whether division of labor is favored by natural selection, such that the “clonality window” is also a prerequisite for division of labor in Michod’s trade-off scenario.Peer reviewe
3-(4-Hydroxy-2,3,5-trimethylphenyl)-3-(4-hydroxyphenyl)isobenzofuran-1(3H)-one
Get PDF3-(4-hydroxy-2,3,5-trimethylphenyl)-3-(4-hydroxyphenyl)isobenzofuran-1(3H)-one is a derivative of the well-known acid/base indicator, phenolphthalein. We report the synthesis and the molecular structure of the title compound as determined by single-crystal X-ray diffraction. 1H and 13C NMR spectroscopy, IR spectroscopy, and mass spectrometry data have been provided.Peer reviewe
Emerging market SMEs’ internationalization enablers and their influence on internationalization patterns : the case of Turkish automotive suppliers
Get PDFSmall and medium-sized enterprises (SMEs) in emerging markets (EMs) are increasingly engaging in internationalization despite facing resource constraints and institutional barriers. However, there is limited understanding of how internationalization enablers influence internationalization patterns in these contexts. We investigate how networks, strategic entrepreneurship, and government support shape the speed, scope, and scale of internationalization among EM SMEs. Analyzing Turkish SMEs in the automotive supplier industry, we adopt a multiple case study approach to examine how they mobilize internal and external enablers under conditions of institutional duality and market volatility. Our findings reveal that institutional and business networks accelerate initial market entry and broaden geographic reach, while social networks play only a marginal role. Strategic entrepreneurship, particularly through frugal innovation, learning, and alliances, enables firms to expand and sustain international operations over time. Government support mechanisms, such as trade fair subsidies and export grants, play a critical role in reducing entry barriers and extending foreign market reach, although their effect on scale remains limited.Peer reviewe
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