A5065665606- Advanced NMR Techniques and Applications
- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- NMR spectroscopy and applications
- Particle accelerators and beam dynamics
- Muon and positron interactions and applications
- Advancements in Battery Materials
- Rare-earth and actinide compounds
- Asymmetric Synthesis and Catalysis
- Superconducting Materials and Applications
- Advanced Battery Materials and Technologies
- Material Dynamics and Properties
- Nuclear Physics and Applications
- Ionic liquids properties and applications
- Physics of Superconductivity and Magnetism
- Atomic and Subatomic Physics Research
- Synthetic Organic Chemistry Methods
- Bone Tissue Engineering Materials
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Electronic and Structural Properties of Oxides
- ZnO doping and properties
- 2D Materials and Applications
- Crystallography and Radiation Phenomena
- Dental materials and restorations
Gilead Sciences (United States)
2013-2025
TRIUMF
2022-2024
University of Victoria
2022-2024
University of British Columbia
2014-2023
Simon Fraser University
2023
Queen's University Belfast
2019-2022
Vancouver Biotech (Canada)
2018-2020
California Institute of Technology
2006-2014
Mount Allison University
2012-2014
α-Quaternary ketones are accessed through novel enantioselective alkylations of allyl and propargyl electrophiles by unstabilized prochiral enolate nucleophiles in the presence palladium complexes with various phosphinooxazoline (PHOX) ligands. Excellent yields high enantiomeric excesses obtained from three classes precursor: enol carbonates, silanes, racemic β-ketoesters. Each these substrate functions nearly identical efficiency terms yield enantioselectivity. Catalyst discovery...
Herein we report the first enantioselective total synthesis of (+)-dichroanone, confirming absolute configuration natural product. This protecting group-free route features application our Tsuji allylation in context a product synthesis. Additionally, this 11-step preparation molecule from commercial material novel Kumada-aromatization strategy and rapid sequence for conversion phenol to hydroxy-p-benzoquinone.
The copper(I) iodide catalyzed phosphine/aryl halide coupling procedure of Buchwald et al. provides modular, robust, and scaleable access to phosphinooxazoline (PHOX) ligands. advantages this method are highlighted by the convenient synthesis PHOX ligands with varied steric electronic properties, which would be challenging synthesize other protocols.
In a recent Letter by Romanenko et al., 1 the authors used lowenergy muon spin rotation (LE-lSR) 2,3 to measure Meissner screening profile in cutouts from Nb superconducting radio frequency (SRF) cavities, systematically comparing how different surface treatments affect properties of elemental type-II superconductor.They reported "strong" modification character upon mild baking at 120 C for 48 h, 4 which was interpreted as depth-dependent carrier mean-free-path resulting "gradient vacancy...
Ring a ding: The meroterpenoid natural product (+)-liphagal has been synthesized enantioselectively in 19 steps from commercially available materials. trans-homodecalin system was achieved by ring expansion followed stereoselective hydrogenation.
The first palladium-catalyzed enantioselective oxidation of secondary alcohols has been developed, utilizing the readily available diamine (-)-sparteine as a chiral ligand and molecular oxygen stoichiometric oxidant. Mechanistic insights regarding role base hydrogen-bond donors have resulted in several improvements to original system. Namely, addition cesium carbonate tert-butyl alcohol greatly enhances reaction rates, promoting rapid resolutions. use chloroform solvent allows ambient air...
Pteridinone-based Toll-like receptor 7 (TLR7) agonists were identified as potent and selective alternatives to the previously reported adenine-based agonists, leading discovery of GS-9620. Analogues optimized for immunomodulatory activity selectivity versus other TLRs, based on differential induction key cytokines including interferon α (IFN-α) tumor necrosis factor (TNF-α). In addition, physicochemical properties adjusted achieve desirable in vivo pharmacokinetic pharmacodynamic properties....
We report depth-resolved measurements of the Meissner screening profile in several surface-treated Nb samples using low-energy muon spin rotation (LE-$\mu$SR). In these experiments, implanted positive muons, whose stopping depths below Nb's surface were adjusted between ~10 nm to ~150 nm, reveal field distribution inside superconducting element via their spin-precession (communicated through radioactive decay products). compare how is modified by different treatments commonly employed...
Despite suppressive antiretroviral therapy (ART), HIV-1 persists in latent reservoirs that seed new HIV infections if ART is interrupted, necessitating lifelong for people with HIV. Activation of during could improve recognition and elimination infected cells by the immune system. Protein kinase C (PKC) isozymes increase transcription hence are potential latency reversal agents. However, clinical utility PKCs this application limited due to toxicity, which poorly understood. Our studies...
Currently, no known material retains its photoinduced metallic conductivity over a long time while also exhibiting repeatable metal-to-insulator recovery. Here, we demonstrate such highly insulator-to-metal transition in yttrium oxyhydride (YOxHy) epitaxial thin films. The temperature (T) dependence of the electrical resistivity (ρ) films transforms from insulating to state (dρ/dT > 0) under ultraviolet laser illumination. YOxHy film recovers original when heated (125 °C) an Ar atmosphere...
A new high field spectrometer has been built to extend the capabilities of $\beta$-detected nuclear magnetic resonance ($\beta$-NMR) facility at TRIUMF. This beamline extension allows $\beta$-NMR spectroscopy be performed with fields up 200 mT parallel a sample's surface (perpendicular ion beam), allowing depth-resolved studies local electromagnetic spin polarized probes much higher applied than previously available in this configuration. The primary motivation and application is allow...
A mismatch in bone and implant elastic modulus can lead to aseptic loosening ultimately failure. Selective elemental composition of titanium (Ti) alloys coupled with surface treatment be used improve osseointegration reduce bacterial adhesion. The biocompatibility antibacterial properties Ti-35Nb-7Zr-6Ta (TNZT) using fibre laser were assessed this work, due its excellent material (low Young’s non-toxicity) the promising attributes (very fast, non-contact, clean only causes changes without...
We investigated the depth, temperature, and molecular-weight (MW) dependence of γ-relaxation in polystyrene glasses using implanted 8Li+ β-detected nuclear magnetic resonance. Measurements were performed on thin films with MW ranging from 1.1 to 641 kg/mol. The temperature average 8Li spin-lattice relaxation time (T1avg) was measured near free surface bulk. Spin-lattice is caused by phenyl ring flips, which involve transitions between local minima over free-energy barriers enthalpic entropic...
Abstract We report measurements of the first-flux-penetration field in surface-treated and coated Nb samples using <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mi>μ</mml:mi> <mml:mtext>SR</mml:mtext> stretchy="false">)</mml:mo> </mml:mrow> </mml:math> . Using thin Ag foils as energy moderators for implanted muon spin-probes, we ‘profile’ vortex penetration <mml:msub> <mml:mn>0</mml:mn> </mml:msub>...
β-NMR measurements indicate there is enhanced phenyl ring dynamics near the free surface in polystyrene thin films.
Experiments reveal muon-polaron complexes in Cr${}_{2}$O${}_{3}$. Similar entities may exist many magnetic insulators and semiconductors, where they can be used as proxies to understand the impact of hydrogen impurities.
Abstract Superconducting radio frequency (SRF) cavities, which are critical components in many particle accelerators, need to be operated the Meissner state avoid strong dissipation from magnetic vortices. For a defect-free superconductor, maximum attainable field for operation is set by superheating field, <?CDATA $B_{\mathrm{sh}}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>B</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">s</mml:mi>...
Diffusion of ${\mathrm{Li}}^{+}$ in (111) oriented thin films the spinels ${\mathrm{Li}}_{4}{\mathrm{Ti}}_{5}{\mathrm{O}}_{12}$ and ${\mathrm{LiTi}}_{2}{\mathrm{O}}_{4}$ has been studied with $^{8}\mathrm{Li}\phantom{\rule{4pt}{0ex}}\ensuremath{\beta}$-detected NMR temperature range between 5 310 K. In ${\mathrm{Li}}_{4}{\mathrm{Ti}}_{5}{\mathrm{O}}_{12}$, spin-lattice relaxation rate ($1/{T}_{1}$) versus shows a clear maximum around 100 K ($={T}_{\mathrm{max}}$) which we attribute to...
Pd-catalyzed enantioselective alkylation in conjunction with further synthetic elaboration enables the formal total syntheses of a number “classic” natural product target molecules. This publication highlights recent methods for setting quaternary and tetrasubstituted tertiary carbon stereocenters to address hurdles encountered over many decades across multiple compound classes spanning carbohydrate derivatives, terpenes, alkaloids. These will impact both academic industrial settings, where...
Aus kommerziell erhältlichen Verbindungen wurde das natürliche Meroterpenoid (+)-Liphagal enantioselektiv in 19 Stufen synthetisiert. Das trans-Homodecalin-System dabei durch eine Ringerweiterung mit anschließender stereoselektiver Hydrierung eingeführt.
Muon spin rotation/relaxation measurements show clear evidence for magnetism in 2.2 nm gold nanoparticles capped with butanethiol. At low temperatures (1.8 K), there is significant relaxation which decreases as a function of both the applied longitudinal magnetic field and increasing temperature. The results indicate that are spatially inhomogeneous electronic moments fluctuate wide distribution correlation times. Possible explanations discussed.
We report herein a means to modify the reactivity of alkenes, and particularly their selectivity toward reactions with nonpolar reactants (e.g., free radicals) in supercritical carbon dioxide near critical point. Rate constants for radical addition light hydrogen isotope muonium ethylene, vinylidene fluoride, chloride are compared over range pressures temperatures. Near dioxide's point, ethylene exhibits speeding up, while halogenated analogues display slowing. This suggests that as solvent...
By measuring the prototypical antiferromagnet α-Fe_{2}O_{3}, we show that it is possible to determine static spin orientation and dynamic correlations within nanometers from an antiferromagnetic surface using nuclear polarization of implanted ^{8}Li^{+} ions detected with β-NMR. Remarkably, first-order Morin reorientation in single crystal α-Fe_{2}O_{3} occurs at same temperature all depths between 1 100 nm (110) surface; however, experiences increased 1/T_{1} relaxation rate shallow...