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Physical Review Letters Jan 2023Circular Rydberg states are excellent tools for quantum technologies, with large mutual interactions and long lifetimes in the tens of milliseconds range, 2 orders of...
Circular Rydberg states are excellent tools for quantum technologies, with large mutual interactions and long lifetimes in the tens of milliseconds range, 2 orders of magnitude larger than those of laser-accessible Rydberg states. However, such lifetimes are observed only at zero temperature. At room temperature, blackbody-radiation-induced transfers cancel this essential asset of circular states, which have thus been used mostly so far in specific, complex cryogenic experiments. We demonstrate here, on a laser-cooled atomic sample, a circular state lifetime of more than 1 millisecond at room temperature for a principal quantum number 60. A simple plane-parallel capacitor efficiently inhibits the blackbody-radiation-induced transfers. One of the capacitor electrodes is fully transparent and provides large optical access to the atoms. This result paves the way to a wide range of quantum metrology and quantum simulation room-temperature experiments with long-lived, trapped circular Rydberg atoms in inhibition capacitors with full optical access.
PubMed: 36706390
DOI: 10.1103/PhysRevLett.130.023202 -
Living Reviews in Relativity 2005We review the main properties, demographics and applications of binary and millisecond radio pulsars. Our knowledge of these exciting objects has greatly increased in... (Review)
Review
UNLABELLED
We review the main properties, demographics and applications of binary and millisecond radio pulsars. Our knowledge of these exciting objects has greatly increased in recent years, mainly due to successful surveys which have brought the known pulsar population to over 1700. There are now 80 binary and millisecond pulsars associated with the disk of our Galaxy, and a further 103 pulsars in 24 of the Galactic globular clusters. Recent highlights have been the discovery of the first ever double pulsar system and a recent flurry of discoveries in globular clusters, in particular Terzan 5.
ELECTRONIC SUPPLEMENTARY MATERIAL
Supplementary material is available for this article at 10.12942/lrr-2005-7.
PubMed: 28179869
DOI: 10.12942/lrr-2005-7 -
Nature Jul 2020Light-driven sodium pumps actively transport small cations across cellular membranes. These pumps are used by microorganisms to convert light into membrane potential and...
Light-driven sodium pumps actively transport small cations across cellular membranes. These pumps are used by microorganisms to convert light into membrane potential and have become useful optogenetic tools with applications in neuroscience. Although the resting state structures of the prototypical sodium pump Krokinobacter eikastus rhodopsin 2 (KR2) have been solved, it is unclear how structural alterations over time allow sodium to be translocated against a concentration gradient. Here, using the Swiss X-ray Free Electron Laser, we have collected serial crystallographic data at ten pump-probe delays from femtoseconds to milliseconds. High-resolution structural snapshots throughout the KR2 photocycle show how retinal isomerization is completed on the femtosecond timescale and changes the local structure of the binding pocket in the early nanoseconds. Subsequent rearrangements and deprotonation of the retinal Schiff base open an electrostatic gate in microseconds. Structural and spectroscopic data, in combination with quantum chemical calculations, indicate that a sodium ion binds transiently close to the retinal within one millisecond. In the last structural intermediate, at 20 milliseconds after activation, we identified a potential second sodium-binding site close to the extracellular exit. These results provide direct molecular insight into the dynamics of active cation transport across biological membranes.
Topics: Binding Sites; Crystallography; Electrons; Flavobacteriaceae; Ion Transport; Isomerism; Lasers; Protons; Quantum Theory; Retinaldehyde; Rhodopsins, Microbial; Schiff Bases; Sodium; Sodium-Potassium-Exchanging ATPase; Spectrum Analysis; Static Electricity; Time Factors
PubMed: 32499654
DOI: 10.1038/s41586-020-2307-8 -
Optics Letters Apr 2020A nanosecond-millisecond combined pulse laser (CPL) drilling method was proposed for drilling alumina ceramic. The total energy consumption of the CPL drilling was 1/7...
A nanosecond-millisecond combined pulse laser (CPL) drilling method was proposed for drilling alumina ceramic. The total energy consumption of the CPL drilling was 1/7 of that of a conventional millisecond laser, and the drilling quality was better. The simulation results demonstrated that, due to the nonuniform reflection of the millisecond laser in the keyhole, the ellipse keyhole ablated by the off-axis incident nanosecond pulses had no effect on the circularity of the through hole. In addition, the multireflection of the laser in the keyhole enhanced the absorption, so the keyhole ablated by the nanosecond pulses could be used as a target for limiting the absorption of the subsequent millisecond pulses. In this context, the keyhole could be used to reduce the hole diameter if the subsequent millisecond laser had a bigger spot size, and this CPL drilling method could be used as an effective group hole drilling method.
PubMed: 32235975
DOI: 10.1364/OL.383207 -
Nature Communications Apr 2024Porous carbons with concurrently high specific surface area and electronic conductivity are desirable by virtue of their desirable electron and ion transport ability,...
Porous carbons with concurrently high specific surface area and electronic conductivity are desirable by virtue of their desirable electron and ion transport ability, but conventional preparing methods suffer from either low yield or inferior quality carbons. Here we developed a lithiothermal approach to bottom-up synthesize highly meso-microporous graphitized carbon (MGC). The preparation can be finished in a few milliseconds by the self-propagating reaction between polytetrafluoroethylene powder and molten lithium (Li) metal, during which instant ultra-high temperature (>3000 K) was produced. This instantaneous carbon vaporization and condensation at ultra-high temperatures and in ultra-short duration enable the MGC to show a highly graphitized and continuously cross-coupled open pore structure. MGC displays superior electrochemical capacitor performance of exceptional power capability and ultralong-term cyclability. The processes used to make this carbon are readily scalable to industrial levels.
PubMed: 38664439
DOI: 10.1038/s41467-024-47916-y -
ACS Nano Jan 2021Controllable phase engineering is vital for precisely tailoring material properties since different phase structures have various electronic states and atomic...
Controllable phase engineering is vital for precisely tailoring material properties since different phase structures have various electronic states and atomic arrangements. Rapid synthesis of thermodynamically metastable materials, especially two-dimensional metastable materials, with high efficiency and low cost remains a large challenge. Here we report flash Joule heating (FJH) as an electrothermal method to achieve the bulk conversion of transition metal dichalcogenides, MoS and WS, from 2H phases to 1T phases in milliseconds. The conversions can reach up to 76% of flash MoS using tungsten powder as conductive additive. Different degrees of phase conversion can be realized by controlling the FJH conditions, such as reaction duration and additives, which allows the study of ratio-dependent properties. First-principles calculations confirm that structural processes associated with the FJH, such as vacancy formation and charge accumulation, result in stabilization of the 1T phases. FJH offers rapid access to bulk quantities of the hitherto hard-to-access 1T phases, a promising method for further fundamental research and diverse applications of metastable phases.
PubMed: 33412009
DOI: 10.1021/acsnano.0c08460 -
Molecular Pharmaceutics Feb 2018We report the development of a new spray-drying and nanoparticle assembly process (SNAP) that enables the formation of stable, yet rapidly dissolving, sub-200 nm...
We report the development of a new spray-drying and nanoparticle assembly process (SNAP) that enables the formation of stable, yet rapidly dissolving, sub-200 nm nanocrystalline particles within a high T glassy matrix. SNAP expands the class of drugs that spray-dried dispersion (SDD) processing can address to encompass highly crystalline, but modestly hydrophobic, drugs that are difficult to process by conventional SDD. The process integrates rapid precipitation and spray-drying within a custom designed nozzle to produce high supersaturations and precipitation of the drug and high T glassy polymer. Keeping the time between precipitation and drying to tens of milliseconds allows for kinetic trapping of drug nanocrystals in the polymer matrix. Powder X-ray diffraction, solid state 2D NMR, and SEM imaging shows that adding an amphiphilic block copolymer (BCP) to the solvent gives essentially complete crystallization of the active pharmaceutical ingredient (API) with sub-200 nm domains. In contrast, the absence of the block copolymer results in the API being partially dispersed in the matrix as an amorphous phase, which can be sensitive to changes in bioavailability over time. Quantification of the API-excipient interactions by 2D C-H NMR correlation spectroscopy shows that the mechanism of enhanced nanocrystal formation is not due to interactions between the drug and the BCP, but rather the BCP masks interactions between the drug and hydrophobic regions of the matrix polymers. BCP-facilitated SNAP samples show improved stability during aging studies and rapid dissolution and release of API in vitro.
Topics: Biological Availability; Chemistry, Pharmaceutical; Desiccation; Drug Compounding; Drug Liberation; Excipients; Hydrophobic and Hydrophilic Interactions; Magnetic Resonance Spectroscopy; Nanoparticles; Polymers; Solubility; X-Ray Diffraction
PubMed: 29244515
DOI: 10.1021/acs.molpharmaceut.7b00866 -
Neuroscience Jan 2022Spectrotemporal integration is a key function of our auditory system for discriminating spectrotemporally complex sounds, such as words. Response latency in the auditory...
Spectrotemporal integration is a key function of our auditory system for discriminating spectrotemporally complex sounds, such as words. Response latency in the auditory cortex is known to change with the millisecond time-scale depending on acoustic parameters, such as sound frequency and intensity. The functional significance of the millisecond-range latency difference in the integration remains unclear. Actually, whether the auditory cortex has a sensitivity to the millisecond-range difference has not been systematically examined. Herein, we examined the sensitivity in the primary auditory cortex (A1) using voltage-sensitive dye imaging techniques in guinea pigs. Bandpass noise bursts in two different bands (band-noises), centered at 1 and 16 kHz, respectively, were used for the examination. Onset times of individual band-noises (spectral onset-times) were varied to virtually cancel or magnify the latency difference observed with the band-noises. Conventionally defined nonlinear effects in integration were analyzed at A1 with varying sound intensities (or response latencies) and/or spectral onset-times of the two band-noises. The nonlinear effect measured in the high-frequency region of the A1 linearly changed depending on the millisecond difference of the response onset-times, which were estimated from the spatially-local response latencies and spectral onset-times. In contrast, the low-frequency region of the A1 had no significant sensitivity to the millisecond difference. The millisecond-range latency difference may have functional significance in the spectrotemporal integration with the millisecond time-scale sensitivity at the high-frequency region of A1 but not at the low-frequency region.
Topics: Acoustic Stimulation; Animals; Auditory Cortex; Auditory Perception; Guinea Pigs; Noise; Reaction Time; Sound
PubMed: 34762984
DOI: 10.1016/j.neuroscience.2021.10.030 -
The Journal of Neuroscience : the... Nov 2014Inhibitory neurons in cortical circuits play critical roles in composing spike timing and oscillatory patterns in neuronal activity. These roles in turn require coherent...
Inhibitory neurons in cortical circuits play critical roles in composing spike timing and oscillatory patterns in neuronal activity. These roles in turn require coherent activation of interneurons at different timescales. To investigate how the local circuitry provides for these activities, we applied resampled cross-correlation analyses to large-scale recordings of neuronal populations in the cornu ammonis 1 (CA1) and CA3 regions of the hippocampus of freely moving rats. Significant counts in the cross-correlation of cell pairs, relative to jittered surrogate spike-trains, allowed us to identify the effective couplings between neurons in CA1 and CA3 hippocampal regions on the timescale of milliseconds. In addition to putative excitatory and inhibitory monosynaptic connections, we uncovered prominent millisecond timescale synchrony between cell pairs, observed as peaks in the central 0 ms bin of cross-correlograms. This millisecond timescale synchrony appeared to be independent of network state, excitatory input, and γ oscillations. Moreover, it was frequently observed between cells of differing putative interneuronal type, arguing against gap junctions as the sole underlying source. Our observations corroborate recent in vitro findings suggesting that inhibition alone is sufficient to synchronize interneurons at such fast timescales. Moreover, we show that this synchronous spiking may cause stronger inhibition and rebound spiking in target neurons, pointing toward a potential function for millisecond synchrony of interneurons in shaping and affecting timing in pyramidal populations within and downstream from the circuit.
Topics: Animals; CA1 Region, Hippocampal; CA3 Region, Hippocampal; Cortical Synchronization; Gamma Rhythm; Gap Junctions; Male; Neural Inhibition; Neurons; Rats; Rats, Long-Evans; Theta Rhythm; Time Factors
PubMed: 25378164
DOI: 10.1523/JNEUROSCI.1091-14.2014 -
Nanoscale Aug 2019Mechanically strong carbon nanotube (CNT) fibers have increasingly become the focus of the present research in the fiber industry. However, the weak or even a lack of...
Mechanically strong carbon nanotube (CNT) fibers have increasingly become the focus of the present research in the fiber industry. However, the weak or even a lack of interconnections between adjacent CNTs induces much inter-tube slippages during fiber failure, and thus results in their low mechanical strength. Moreover, achieving fast cross-linking between neighbouring CNTs on a large scale to prevent the failure by slip is still a big challenge. Herein we report an ultrafast and continuous tension-annealing process to achieve the considerably improved tube alignment and strong covalent cross-linking of neighbouring CNTs in milliseconds, resulting in great improvement of the fiber performance. The CNT fibers were heated to high temperature (∼2450 °C) by Joule heating under the applied tension and subsequently annealed for just 12 ms. Due to the rapid electromechanical response of the fibers, instant nanotube rearrangements coupled by the formation of cross-links robustly bonding the adjacent CNTs occurred at power-on, which could be attributed to the considerable increases of strength and modulus by factors of 2.9 (up to 3.2 GPa) and 4.8 (up to 123 GPa), respectively. The resultant fibers showed high specific strength (2.2 N per tex), comparable with that of PAN-based carbon fibers, and high specific electrical conductivity higher than that of PAN-based carbon fibers. Moreover, the obtained strongly crosslinked and highly dense structures also endowed the fibers with the significantly improved thermal stability under a high-temperature oxidation atmosphere. Moreover, a continuous tension-annealing process was designed to achieve the large scale production of high performance fibers with the average strength of 2.2 GPa. The high-toughness, lightweight and continuous features together with their outstanding mechanical and electrical properties would certainly boost the large-scale applications of CNT fibers.
PubMed: 31304941
DOI: 10.1039/c9nr03400e