A5028475506- Physics of Superconductivity and Magnetism
- Rare-earth and actinide compounds
- Iron-based superconductors research
- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Neuropeptides and Animal Physiology
- Neurotransmitter Receptor Influence on Behavior
- Superconductivity in MgB2 and Alloys
- Pain Mechanisms and Treatments
- Receptor Mechanisms and Signaling
- Superconducting Materials and Applications
- Opioid Use Disorder Treatment
- Magnetic Properties of Alloys
- Pharmacological Receptor Mechanisms and Effects
- Theoretical and Computational Physics
- Advanced Thermoelectric Materials and Devices
- Alcohol Consumption and Health Effects
- Inorganic Fluorides and Related Compounds
- Neuroscience and Neuropharmacology Research
- Inorganic Chemistry and Materials
- Forensic Toxicology and Drug Analysis
- Nuclear materials and radiation effects
- Substance Abuse Treatment and Outcomes
- Atomic and Subatomic Physics Research
- Material Science and Thermodynamics
Queen's Medical Centre
2021-2023
University of Nottingham
1960-2023
University of Bristol
1996-2022
University of Waterloo
2006-2020
University of Cambridge
2019
Gomal University
2019
University of Pecs
2019
University of Bath
2019
Virginia Commonwealth University
2017
South London and Maudsley NHS Foundation Trust
2009
Background and Purpose GPCRs can signal through both G proteins β‐arrestin2. For the μ‐opioid receptor, early experimental evidence from a single study suggested that protein signalling mediates analgesia, whereas β‐arrestin2 respiratory depression constipation. Consequently, for more than decade, much research effort has been focused on developing biased agonists preferentially target over β‐arrestin signalling, as it was believed such drugs would be analgesics devoid of depressant...
PZM21 is a novel μ-opioid receptor ligand that has been reported to induce minimal arrestin recruitment and be devoid of the respiratory depressant effects characteristic classical μ ligands such as morphine. We have re-examined signalling profile its ability depress respiration.
Background and Purpose Fentanyl overdose deaths have reached “epidemic” levels in North America. Death opioid invariably results from respiratory depression. In the present work, we characterized how fentanyl depresses respiration, by comparing with heroin morphine, active breakdown product of heroin, sought to determine factors, addition high potency, that contribute lethality fentanyl. Experimental Approach Respiration (rate tidal volume) was measured awake, freely moving mice whole body...
The resistivity of the heavy-fermion superconductor CeCoIn5 was measured as a function temperature, down to 25 mK and in magnetic fields up 16 T applied perpendicular basal plane. With increasing field, we observe suppression non-Fermi liquid behavior, rho approximately T, development Fermi state, with its characteristic rho=rho(0)+AT2 dependence. field dependence T2 coefficient shows critical behavior an exponent 1.37. This is evidence for field-induced quantum point (QCP), occurring at...
The thermal conductivity kappa of the layered s-wave superconductor NbSe2 was measured down to T(c)/100 throughout vortex state. With increasing field, we identify two regimes: one with localized states at fields very near H(c1) and highly delocalized quasiparticle excitations higher fields. associated length scales are naturally explained as multiband superconductivity, distinct small large superconducting gaps on different sheets Fermi surface. This behavior is compared that MgB2 conventional V3Si.
The transport of heat and charge in the overdoped cuprate superconductor Tl(2)Ba2CuO(6+delta) was measured down to low temperature. In normal state, obtained by applying a magnetic field greater than upper critical field, Wiedemann-Franz law is verified hold perfectly. superconducting large residual linear term observed thermal conductivity, quantitative agreement with BCS theory for d-wave superconductor. This compelling evidence that electrons cuprates form Fermi liquid, no indication...
Heat transport in the cuprate superconductors YBa$_2$Cu$_3$O$_{y}$ and La$_{2-x}$Sr$_x$CuO$_4$ was measured at low temperatures as a function of doping. A residual linear term kappa_{0}/T is observed throughout superconducting region it decreases steadily Mott insulator approached from overdoped regime. The low-energy quasiparticle gap extracted seen to scale closely with pseudogap. ubiquitous presence nodes tracking pseudogap shows that overall remains pure d-wave form phase diagram, which...
Aim To examine the risk to heroin users of also using gabapentin or pregabalin (gabapentoids). Design Multi-disciplinary study: we (a) examined trends in drug-related deaths and gabapentoid prescription data England Wales test for evidence that any increase mentioning is associated with prescribing concomitant opioid use; (b) interviewed people a history use about their polydrug involving pregabalin; (c) studied respiratory depressant effects absence presence morphine mice determine whether...
A residual linear term is observed in the thermal conductivity of optimally doped ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8}$ at very low temperatures whose magnitude excellent agreement with value expected from Fermi-liquid theory and d-wave energy spectrum measured by photoemission spectroscopy no adjustable parameters. This solid basis allows us to make a quantitative analysis thermodynamic properties temperature establish that thermally excited quasiparticles...
The in-plane resistivity, rho, and thermal conductivity, kappa, of a single crystal Na_0.7CoO_2 were measured down to 40 mK. Verification the Wiedemann-Franz law, kappa/T = L_0/rho as T -> 0, observation T^2 dependence rho at low temperature, rho_0 + AT^2, establish existence well-defined Fermi-liquid state. value coefficient A reveals enormous electron-electron scattering, characterized by largest Kadowaki-Woods ratio, A/gamma^2, encountered in any material. rapid suppression with magnetic...
Opioids are the most common drugs associated with unintentional drug overdose. Death results from respiratory depression. Prolonged use of opioids in development tolerance but degree is thought to vary between different effects drugs. Many opioid addicts regularly consume alcohol (ethanol), and post-mortem analyses overdose deaths have revealed an inverse correlation blood morphine ethanol levels. In present study, we determined whether reduced depressant opioids. Mice were treated...
The effect of vortices on quasiparticle transport in cuprate superconductors was investigated by measuring the low temperature thermal conductivity YBa_2Cu_3O_6.9 magnetic fields up to 8 T. residual linear term (as T \to 0) is found increase with field, directly reflecting occupation extended states. A study for different Zn impurity concentrations reveals a good agreement recent calculations d-wave superconductor, thereby shedding light nature scattering both impurities and vortices. It...
Thermal conductivity and specific heat were measured in the superconducting state of heavy fermion material Ce_{1-x}La_{x}CoIn_{5}. With increasing impurity concentration x, suppression T_{c} is accompanied by increase residual electronic expected a d-wave superconductor, but it occurs parallel with decrease thermal conductivity. This contrasting behavior reveals presence uncondensed electrons coexisting nodal quasiparticles. An extreme multiband scenario proposed, gap on heavy-electron...
Heat and charge transport were used to probe the magnetic field-tuned quantum critical point in heavy-fermion metal CeCoIn$_5$. A comparison of electrical thermal resistivities reveals three characteristic energy scales. Fermi-liquid regime is observed below $T_{FL}$, with both coefficients diverging parallel $T_{FL}\to 0$ as $H\to H_c$, field. The temperature antiferromagnetic spin fluctuations, $T_{SF}$, tuned a minimum but {\it finite} value at $H_c$, which coincides end $T$-linear...
Agonists at the δ opioid receptor are known to be potent antihyperalgesics in chronic pain models and effective of anxiety depression. However, some agonists have proconvulsant properties while tolerance therapeutic effects can develop. Previous evidence indicates that different acting differentially engage signaling regulatory pathways with significant on behavioral outcomes. As such, interest is now growing development biased as a potential means target specific potentially improve profile...
Oxycodone, a prescription opioid, is major drug of abuse, especially in the USA, and contributes significantly to opioid overdose deaths each year. Overdose result primarily from respiratory depression. We have studied depression by oxycodone characterized how tolerance develops on prolonged exposure drug. investigated role PKC maintaining examined whether ethanol or pregabalin reverses oxycodone-induced tolerance.
The thermal conductivity of borocarbide superconductor $\mathrm{LuNi}{}_{2}{\mathrm{B}}_{2}\mathrm{C}$ was measured down to 70 mK $({T}_{c}/200)$ in a magnetic field perpendicular the heat current from $H\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$ above ${H}_{c2}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}7\phantom{\rule{0ex}{0ex}}\mathrm{T}$. As soon as vortices enter sample, conduction at $T\ensuremath{\rightarrow}0$ grows rapidly, showing unambiguously that delocalized...
Opioids are widely used medicinally as analgesics and abused for hedonic effects, actions that each complicated by substantial risks such cardiorespiratory depression. These drugs mimic peptides β-endorphin, which has a key role in endogenous analgesia. The β-endorphin the central nervous system originates from pro-opiomelanocortin (POMC) neurons arcuate nucleus of solitary tract (NTS). Relatively little is known about NTSPOMC but their position within sensory vagus led us to test hypothesis...
Low temperature heat transport was used to investigate the ground state of high-purity single crystals lightly-doped cuprate YBa$_{2}$Cu$_{3}$O$_{6.33}$. Samples were measured on either side superconducting phase boundary, in both zero and applied magnetic field. We report observation delocalized fermionic excitations at energy non-superconducting state, which shows that underdoped cuprates is metallic. Its low-energy spectrum appears be similar d-wave superconductor, i.e. nodal. The...
Thermal conductivity measurements were performed on single crystal samples of the superconducting filled-skutterudite compounds PrOs4Sb12 and PrRu4Sb12 both as a function temperature transverse magnetic field. In zero field, low electronic thermal is consistent with fully gapped Fermi surface. For PrOs4Sb12, residual conduction in zero-temperature limit presence nodes energy gap. The for shows rapid rise at fields. PrRu4Sb12, this interpreted terms multiband effects. we consider Doppler...
We present low-temperature thermal conductivity measurements on the cuprate ${\mathrm{Tl}}_{2}{\mathrm{Ba}}_{2}{\mathrm{CuO}}_{6+\ensuremath{\delta}}$ throughout overdoped regime. In $T\ensuremath{\rightarrow}0$ limit, due to $d$-wave nodal quasiparticles provides a bulk measurement of superconducting gap $\ensuremath{\Delta}$. find $\ensuremath{\Delta}$ decrease with increasing doping, magnitude consistent spectroscopic (photoemission and tunneling). This argues for pure simple state in...
Background and Purpose Mitragynine, the major alkaloid in Mitragyna speciosa (kratom), is a partial agonist at μ opioid receptor. CYP3A‐dependent oxidation of mitragynine yields metabolite 7‐OH mitragynine, more efficacious receptor agonist. While both can induce anti‐nociception mice, recent evidence suggests that formed as sufficient to explain anti‐nociceptive effects mitragynine. However, ability receptor‐dependent respiratory depression has not yet been studied. Experimental Approach...