83308 research outputs found
Sort by
Function from confinement:ligand-coated nanoparticles as functional materials
No full textFor nanoparticles stabilized by self-assembled monolayers, the surface-bound molecular species not only modify the core material properties but also provide a handle for interaction with other components, whether they are molecular, nanoscale, or even macroscopic. Importantly, when confined to nanosurfaces, these organic entities exhibit emergent properties that impart unique functionalities to the underlying nanomaterial. In this Review, we examine how these capabilities originate from the structural organization and collective interactions within on-nanoparticle self-assembled monolayers, drawing on examples of quasi-spherical nanoparticles smaller than ca. 8 nm in size. Our focus spans four key categories of function: (i) catalysis and chemical transformation under nanoconfinement, (ii) molecular recognition and sensing, (iii) switching and adaptation, and (iv) programmable nanoparticle assembly. By adopting a systems-chemistry perspective to identify how function is defined by chemical constitution, we elucidate design principles and strategies that we envisage can be broadly applied to a variety of hybrid organic–inorganic nanosystems. We also highlight the current challenges and future opportunities in the field of functional nanoparticles stabilized by self-assembled monolayers. Our aim is to motivate the community to shift toward a perspective in which the organic layer is understood as an active driver of the system functionality rather than a passive component. By harnessing its dynamic and adaptative nature, researchers can design functionally sophisticated and chemically programmable nanomaterials, unlocking unexplored possibilities in active materials, nanocatalysis, molecular recognition, sensing, and delivery
From websites to Wikidata:digitising Scotland’s stories
No full textData connected to our cultural and industrial heritage are often collated by passionate volunteers, typically in the form of blogs and websites. Decades of effort is invested in these sites, which are then vulnerable to data loss due to technical failures, lack/loss of volunteers, or link rot (Chapekis et al., 2024). In collaboration with undergraduate Computer Science students from the University of St Andrews and Wikimedia UK, two unique datasets (created from the websites for Women’s History Scotland and Scottish Brick History) were extracted, cleaned, uploaded to Wikidata, then used to generate creative websites to allow readers to interact with the data. This data paper will explore the pluses and minuses of our approach, and how we would tackle similar datasets in the future
Different intermolecular interactions in solvated and unsolvated isatin-based dithiocarbazate imine derivatives
No full textThe syntheses and structures of 2-fluorobenzyl (Z)-2-(2-oxoindolin-3-ylidene)hydrazine-1-carbodithioate dimethyl sulfoxide monosolvate, C16H12FN3OS2·C2H6OS (1) and 2-fluorobenzyl (Z)-2-(5-bromo-2-oxoindolin-3-ylidene)hydrazine-1-carbodithioate, C16H11BrFN3OS2 (2) are reported. Both structures feature a Z-configuration with respect to the C=N bond and the fluorobenzyl ring is approximately orthogonal to the isatin moiety. For 1, the crystal packing features weak Car—H⋯S (ar = aromatic) hydrogen bonds that link adjacent molecules in a C(10) fashion to form pleated chains propagating along [001] and short S⋯O contacts between dimethyl sulfoxide solvent molecules forming chains along [010]. The N—H hydrogen bond donors in 1 form either intramolecular or discrete N—H⋯O(DMSO) hydrogen bonds. In 2, alternating R22(8)-type pairwise N—H⋯O hydrogen bonds and short F⋯Br contacts link the molecules into chains propagating along [210]. The later unsolvated structure is of notably poorer quality and exhibits disorder in its o-fluorobenzyl group, with a 180° flip and a small twist around the S—C bond. These findings are consistent with the results of Hirshfeld surface analyses
Approximate marked length spectrum rigidity in coarse geometry
No full textWe compare the marked length spectra of isometric actions of groups with non-positively curved features. Inspired by the recent works of Butt, we study approximate versions of marked length spectrum rigidity. We show that for pairs of metrics, the supremum of the quotient of their marked length spectra is approximately determined by their marked length spectra restricted to an appropriate finite set of conjugacy classes. Applying this to fundamental groups of closed negatively curved Riemannian manifolds allows us to refine Butt's result. Our results, however, apply in greater generality and do not require the acting group to be hyperbolic. For example, we are able to compare the marked length spectra associated to mapping class groups acting on their Cayley graphs or on the curve graph
America embraces imperialism and ditches Europe
No full textIn 2025, America abandoned Ukraine and Europe to Russia and chose the imperial past as a future. It is a turning point. Washington nodded eagerly in agreement with Moscow’s insistence on dividing the world into 19th-century-style spheres of influence. AI rapidly replaces hydrocarbons as the main source of wealth and influence. Only states with stockpiles of nuclear weapons remain genuinely sovereign
A catalogue of extensional and contractional structures generated along gravity-driven detachments
No full textAlthough detachments form an integral component of gravity-driven downslope movement, their largely bed-parallel nature can make them difficult to identify in both seismic and outcrop studies. Sediments above bed-parallel detachments (BPDs) associated with intra-stratal deformation are carried passively downslope and therefore represent a form of mass transport deposit (MTD). Using outcrop examples of MTDs created in late-Pleistocene lacustrine sediments around the Dead Sea, we present a catalogue of exceptional extensional and contractional structures generated along BPDs. Detachments may form individual structures that locally ramp to higher structural levels, creating extensional ramps in the upslope direction and contractional ramps further downslope. Alternatively, detachments may comprise multiple strands that kinematically interact with one another via ‘soft-linkage’, or are geometrically coupled via connecting faults to create a ‘hard-linkage’. Lower detachments involving multiple slip surfaces interact with one another to create localised extensional and contractional duplexes, whilst collectively forming the base of the slide sheet. Upper detachments may consist of several strands, or alternatively form ‘soft-linked detachments’ where deformation is distributed across units with no discrete slip surface. Thrusts above detachments frequently follow a ‘piggyback’ sequence with younger shallower thrusts displaying less overall shortening forming downslope of older steeper imbricates. This suggests that they are formed during downslope migration of the duplex rather than upslope propagation of compressive strain during ‘locking up’ of gravity-driven deformation. The fields of extensional and contractional strain may expand and change location during evolution of the slide, leading to normal faults and thrust faults locally overprinting one another. In addition, thrust and normal faults may operate coevally, or locally reactivate one another during positive and negative inversion of individual structures. Transfer of BPD displacement to different levels is achieved by local ramping across older normal and thrust faults, resulting in significant changes to the stratigraphic position of BPDs, together with notable variations in heave across fault zones. Movement on the BPDs is facilitated by high fluid pressures that create sediment injections along the slide planes, especially where normal faults intersect the lower detachment. Where multiple BPDs are formed along the lower detachment, sediment injections cut the upper detachment, suggesting that deformation and movement was longer-lived along the lowermost BPD in a system. Overall, the observation that all measured BPDs (N > 170) consistently display a top-towards the basin sense of displacement suggests that they were sequentially developed through the sediment pile during numerous slope failures, rather than forming synchronously in a single major event that could lead to local apparent reversals in shear sense across adjacent BPDs
The origins of the Tiber Island in Rome
No full textThis paper presents the latest results from a geoarchaeological coring survey of Rome’s central river valley: new evidence demonstrates that the Tiber Island did not exist during the early centuries of human habitation at the site of Rome. Instead, the area was characterised by a low, seasonal bar formation on the riverbed, which would conceivably have aided prehistoric fording activity. The Tiber Island first emerged as a permanent land mass as a result of rapid sedimentation in the late sixth century b.c.e. We discuss the potential causes of this major topographic change and argue that intensive deforestation to support building activities in the region was a major factor. Overall, this research sheds light on the dynamic landscape of early Rome as well as new details on the consequences of environmental exploitation that occurred alongside archaic urbanisation in Tyrrhenian central Italy
Quasi-geostrophic vortex vertical alignment over bathymetry
No full textWe consider the vertical alignment of two vortices over an isolated bathymetric feature in a three-layer, quasi-geostrophic model. Vortex vertical alignment is one of the two elementary mechanisms which, with vortex merger, is responsible for the formation of large vortices. This, in turn, contributes to the inverse energy cascade in large-scale oceanic flows. In particular, vortex vertical alignment transfers baroclinic energy to barotropic energy. When the vortices' potential vorticity is of the same order as the bathymetric potential vorticity, the alignment of cyclonic vortices is favoured over seamounts and impeded over basins. Moreover, in the latter case, vortices also often strained out. However, if the bathymetric potential vorticity associated with seamount is large compared to the potential vorticity of the cyclonic vortices, the vertical alignment of the vortices may be delayed due to nonlinear effects
Valence state and defect modulation in reduced Sr-site deficient Pt/Sr<sub>0.95</sub>Ti<sub>0.9</sub>Cr<sub>0.1</sub>O<sub>3-δ</sub> perovskite for enhanced photocatalytic hydrogen production
No full textAs the global energy landscape shifts to a green hydrogen economy, efficient and stable visible-light photocatalysts are increasingly central to optimizing solar-to-hydrogen conversion. Here, a Sr-site-deficient perovskite photocatalyst (R-Pt/Sr0.95Ti0.9Cr0.1O3-δ) was synthesised by a solid-state method, followed by Pt impregnation and hydrogen reduction post treatment. The introduction of A-site deficiency effectively tunes the band structure and facilitates hydrogen evolution, doubling activity compared to stoichiometric analogs. Besides, A-site deficiency reduces overall cation charge and promotes Cr4+ formation. Through spectroscopy and thermal analysis, Cr4+ was identified in the Sr0.95Ti0.9Cr0.1O3-δ perovskite, revealing unexplored oxidation state dynamics. Upon reduction, Cr4+ converts to Cr3+, creating oxygen vacancies and eliminating hole-trap sites. The resulting synergistic active sites greatly boost photocatalytic hydrogen evolution. Specifically, the R-Pt/Sr0.95Ti0.9Cr0.1O3-δ achieved 120.46 μmol/gcat/h under full spectrum and 68.66 μmol/gcat/h under visible light (λ ≥ 420 nm), representing twice and 5 times enhancements relative to stoichiometric R-Pt/SrTi0.9Cr0.1O3-δ and unreduced Pt/Sr0.95Ti0.9Cr0.1O3-δ in visible light separately. This work demonstrates that combining A-site engineering and valence-state modulation provide a helpful strategy for designing high-performance visible-light photocatalysts
Access Repository Dashboard
Do you manage University of St. Andrews - Pure? Access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard!