On the motion of hairy black holes in Einstein-Maxwell-dilaton theories

Starting from the static, spherically symmetric black hole solutions in massless Einstein-Maxwell-dilaton (EMD) theories, we build a "skeleton" action, that is, we phenomenologically replace black holes by an appropriate effective point particle action, which is well suited to the formal treatment of the many-body problem in EMD theories. We find that, depending crucially on the value of their scalar cosmological environment, black holes can undergo steep "scalarization" transitions, inducing large deviations to the general relativistic two-body dynamics, as shown, for example, when computing the first post-Keplerian Lagrangian of EMD theories

Mediterranean-type diet and brain structural change from 73 to 76 years in a Scottish cohort

STUDY FUNDING The data were collected by a Research into Ageing programme grant; research continues as part of the Age UK–funded Disconnected Mind project. The work was undertaken by The University of Edinburgh Centre for Cognitive Ageing and Cognitive Epidemiology, part of the cross-council Lifelong Health and Wellbeing Initiative (MR/K026992/1), with funding from the BBSRC and Medical Research Council. Imaging and image analysis was performed at the Brain Research Imaging Centre (sbirc.ed.ac.uk/), Edinburgh, supported by the Scottish Funding Council SINAPSE Collaboration. Derivation of mean cortical thickness measures was funded by the Scottish Funding Council’s Postdoctoral and Early Career Researchers Exchange Fund awarded by SINAPSE to David Alexander Dickie. L.C.A.C. acknowledges funding from the Scottish Government's Rural and Environment Science and Analytical Services (RESAS) division.Peer reviewedPublisher PD

Highly <i>Z</i>‑Selective and Enantioselective Ring-Opening/Cross-Metathesis Catalyzed by a Resolved Stereogenic-at-Ru Complex

The synthesis of a ruthenium complex that catalyzes <i>Z</i>-selective (up to 98% <i>Z</i>) asymmetric ring-opening/cross-metathesis with high enantioselectivity (up to 95% ee) is reported. The synthesis of the catalyst features the resolution of a chelating N-heterocyclic carbene complex by ligand substitution with a chiral carboxylate

Highly <i>Z</i>‑Selective and Enantioselective Ring-Opening/Cross-Metathesis Catalyzed by a Resolved Stereogenic-at-Ru Complex

The synthesis of a ruthenium complex that catalyzes <i>Z</i>-selective (up to 98% <i>Z</i>) asymmetric ring-opening/cross-metathesis with high enantioselectivity (up to 95% ee) is reported. The synthesis of the catalyst features the resolution of a chelating N-heterocyclic carbene complex by ligand substitution with a chiral carboxylate

Rapidly Cross-Linkable DOPA Containing Terpolymer Adhesives and PEG-Based Cross-Linkers for Biomedical Applications

A new three-component bio-inspired adhesive was synthesized that is a terpolymer composed of a water-soluble segment, an interfacial adhesion segment, and a cross-linking segment. Strong wet adhesion properties are obtained utilizing a 3,4-dihydroxy-l-phenylalanine (DOPA) moiety. Poly­(acrylic acid) provides high water solubility due to strong ionic interactions with water. An acrylic acid <i>N</i>-hydroxysuccinimide ester (NHS) was included in the adhesive polymer to allow rapid cross-linking with thiol-terminated, 3-armed poly­(ethylene glycol) cross-linking agents. The thiol terminal poly­(ethylene glycol) was designed to be bulky to avoid possible penetration of molecules to the cell and tissue. The NHS and thiol groups react within 30 s to form covalent bonds. This design allows for rapid optimization of properties for specific applications. Lap shear strength tests on wet porcine skin demonstrated a 190% increased value in adhesion strength for adhesives having the DOPA moiety. After cross-linking, adhesion was enhanced by 450% over poly­(acrylic acid-<i>co</i>-acrylic acid NHS) and was 240% higher than un-cross-linked poly­(acrylic acid-<i>co</i>-acrylic acid NHS-<i>co</i>-<i>N</i>-methacryloyl-3,4-dihydroxyl-l-phenylalanine). Rheology studies show adhesive viscosity drops significantly at high shear rates, demonstrating its potential to be injected via syringe. The cross-linked adhesive displayed much stronger mechanical properties and higher elastic and viscous moduli than an un-cross-linked adhesive model. Furthermore, the cross-linked adhesive has enhanced moduli near body temperature (38 °C) as compared to room temperature (23 °C), increasing the applications as a biomedical adhesive

Ruthenium Olefin Metathesis Catalysts Featuring a Labile Carbodicarbene Ligand

Ruthenium benzylidene complexes containing a carbodicarbene (CDC) ligand are reported. Mechanistic studies indicate that the CDC ligand can dissociate under relatively mild conditions to afford active olefin metathesis catalysts. These catalysts were found to be effective at ring-closing metathesis (RCM) and ring-opening metathesis polymerization (ROMP) reactions

Fast-Initiating, Ruthenium-based Catalysts for Improved Activity in Highly <i>E</i>‑Selective Cross Metathesis

Ruthenium-based olefin metathesis catalysts bearing dithiolate ligands have been recently employed to generate olefins with high <i>E</i>-selectivity (>99% <i>E</i>) but have been limited by low to moderate yields. In this report, ¹H NMR studies reveal that a major contributing factor to this low activity is the extremely low initiation rates of these catalysts with <i>trans</i> olefins. Introducing a 2-isopropoxy-3-phenylbenzylidene ligand in place of the conventional 2-isopropoxy­benzylidene ligand resulted in catalysts that initiate rapidly under reaction conditions. As a result, reactions were completed in significantly less time and delivered higher yields than those in previous reports while maintaining high stereoselectivity (>99% <i>E</i>)

Catalyst-Dependent Routes to Ring-Opening Metathesis Alternating Copolymers of Substituted Oxanorbornenes and Cyclooctene

The alternating copolymerization of cis-cyclooctene and 1-substituted oxanorbornenes with commercially available ruthenium-based olefin metathesis catalysts was investigated. We determined that RuCl2­(CHPh)­(PCy3)­2 performs a standard alternating copolymerization with these monomers. Unexpectedly, another route to the desired alternating copolymer was revealed. The “sequence editing” route involves the initial polymerization of <i>cis</i>-cyclooctene, followed a ring-opening cross metathesis step that introduces the 1-substituted oxanorbornene monomer in the polycyclooctene chain and largely avoids oxanorborene homopolymerization. Selectivity for alternating diads in the polymer exceeds 90%. Polymer molecular weight can be controlled by linear olefin chain-transfer reagents during sequence editing

Investigations into Ruthenium Metathesis Catalysts with Six-Membered Chelating NHC Ligands: Relationship between Catalyst Structure and Stereoselectivity

A series of ruthenium catalysts bearing five-membered chelating NHC architectures that exhibit very high <i>Z</i>-selectivity in a variety of metathesis reactions have recently been reported. It was envisioned that catalysts possessing six-membered chelates could similarly exhibit high <i>Z</i>-selectivity and address limitations of this methodology. We thus prepared a number of new catalysts and systematically investigated the impact of the NHC and anionic ligand on their stereoselectivity. In standard metathesis assays, only catalysts containing six-membered chelated NHC structures and η²-bound anionic ligands favored the <i>Z</i>-olefin products. In addition, substitution with bulkier <i>N</i>-aryl groups led to improved <i>Z</i>-selectivity. The effect of ligand structure on stereoselectivity discovered in this study will be useful in the future design of highly active and <i>Z</i>-selective ruthenium catalysts

H/D Exchange Processes Catalyzed by an Iridium-Pincer Complex

A PNP-pincer iridium dihydride performs the H/D exchange between aromatic substrates and tertiary hydrosilanes and D₂O or C₆D₆. Complete incorporation of deuterium into sterically accessible C_ar–H and Si–H bonds was observed at a moderate temperature of 80 °C