The Quantum Measurement Spintronic Engine: Using Entanglement to Harvest Vacuum Fluctuations

Several experimental reports have described electrical power output by electronic devices that channel spin-polarized currents across paramagnetic centers. Phononic radiation have been proposed as the source of the engine's energy, though other hypotheses, such as quantum vacuum fluctuations, should also be examined. This paper is the first of a series which will address these hypotheses. Herein, we investigate the more basic hypothesis that quantum vacuum fluctuations power a quantum engine that converts entanglement energy into useful electrical work. The system under review is composed of two atom-level quantum dots that are tunnel-coupled and exhibit a magnetic exchange interaction. This working substance is connected in series with two ferromagnetic electrodes. The engine cycle comprises two strokes. The thermalizing stroke puts the system into equilibrium with the electrode baths, leading to a release of electrical energy into the leads and to an increase in the system entropy due to entanglement. Then the measurement stroke breaks the entanglement between the two quantum dots, thereby reducing its entropy while energizing it on average. Using a perturbative master equation approach, we analytically demonstrate the efficiency of the engine, and we study the cycle numerically to gain insight into the relevant parameters to maximize power. Although the possibility of harvesting energy from the quantum vacuum fluctuations and the interactions with the baths is proven on paper and confirmed by numerical experiments, the efficiency remains low and is unstable. Our results indicate that quantum vacuum fluctuations alone are unlikely to be the energy source in the the quantum spintronic engine experiments that have been reported thus far

Microcirculatory alterations induced by sedation in intensive care patients. Effects of midazolam alone and in association with sufentanil

INTRODUCTION: Sedation is widely used in intensive care unit (ICU) patients to limit the risk of pulmonary barotrauma and to decrease oxygen needs. However, adverse effects of cc5128sedation have not been fully evaluated; in particular, effects of benzodiazepine and opiates on microcirculation have not been extensively studied. The aim of this study was to evaluate the microcirculatory effects of a sedation protocol commonly prescribed in the ICU. METHODS: Ten non-septic patients under controlled ventilation requiring sedation for therapeutic purposes were enrolled in a prospective observational study conducted in an ICU of a university hospital. Sedation was conducted in two successive steps: first, each patient received midazolam (0.1 mg/kg per hour after a bolus of 0.05 mg/kg, then adapted to reach a Ramsay score of between 3 and 5). Second, after one hour, sufentanil was added (0.1 μg/kg per hour after a bolus of 0.1 μg/kg). Arterial pressure, heart rate, cardiac output determined by transthoracic impedance, transcutaneous oxygen (tcPO(2)) and carbon dioxide (tcPCO(2)) pressures, and microcirculatory blood flow determined by laser Doppler flowmetry at rest and during a reactive hyperaemia challenge were measured before sedation (NS period), one hour after midazolam infusion (H period), and one hour after midazolam-sufentanil infusion (HS period). RESULTS: Arterial pressure decreased in both sedation periods, but heart rate, cardiac output, tcPO(2), and tcPCO(2 )remained unchanged. In both sedation periods, microcirculatory changes occurred with an increase in cutaneous blood flow at rest (H period: 207 ± 25 perfusion units [PU] and HS period: 205 ± 25 PU versus NS period: 150 ± 22 PU, p < 0.05), decreased response to ischaemia (variation of blood flow to peak: H period: 97 ± 16 PU and HS period: 73 ± 9 PU versus NS period: 141 ± 14 PU, p < 0.05), and attenuation of vasomotion. CONCLUSION: Sedation with midazolam or a combination of midazolam and sufentanil induces a deterioration of vasomotion and microvascular response to ischaemia, raising the question of whether this effect may further alter tissue perfusion when already compromised, as in septic patients

Encoding information onto the charge and spin state of a paramagnetic atom using MgO tunnelling spintronics

An electrical current that flows across individual atoms or molecules can generate exotic quantum-based behavior, from memristive effects to Coulomb blockade and the promotion of quantum excited states. These fundamental effects typically appear one at a time in model junctions built using atomic tip or lateral techniques. So far, however, a viable industrial pathway for such discrete state devices has been lacking. Here, we demonstrate that a commercialized device platform can serve as this industrial pathway for quantum technologies. We have studied magnetic tunnel junctions with a MgO barrier containing C atoms. The paramagnetic localized electrons due to individual C atoms generate parallel nanotransport paths across the micronic device as deduced from magnetotransport experiments. Coulomb blockade effects linked to tunnelling magnetoresistance peaks can be electrically controlled, leading to a persistent memory effect. Our results position MgO tunneling spintronics as a promising platform to industrially implement quantum technologies

Recovery From Exercise-Induced Muscle Damage: Cold-Water Immersion Versus Whole-Body Cryotherapy

International audiencePurpose: The aim of this study was to compare the effects of cold-water immersion and whole-body cryotherapy on recovery kinetics following exercise induced muscle damage. Methods: Ten physically active men performed single-leg hamstring eccentric exercise comprising 5 sets of 15 repetitions. Immediately post-exercise, subjects were exposed in a randomized cross-over design to cold-water immersion (10 minutes at 10°C) or whole-body cryotherapy (3 minutes at -110°C) recovery. Creatine kinase concentrations, knee flexor eccentric (60°.s-1) and posterior lower limb isometric (60°) strength, single-leg and two leg countermovement jump, muscle soreness and perception of recovery were measured. The tests were performed before, immediately, 24h, 48h and 72h after exercise.Results: Results showed a very likely moderate effect in favour of cold-water immersion for single-leg [Effect Size (ES) = 0.63; 90% Confidence Interval (CI) = -0.13 to 1.38] and two-leg countermovement jump (ES = 0.68; 90% CI = -0.08 to 1.43) 72h after exercise. Soreness was moderately lower 48h after exercise following cold-water immersion (ES = -0.68; 90% CI = 1.44 to 0.07). Perception of recovery was moderately enhanced 24h after exercise for cold water immersion (ES = -0.62; 90% CI = -1.38 to 0.13). Trivial and small effects of condition were found for the other outcomes.Conclusion: Cold-water immersion was more effective in accelerating recovery kinetics than whole-body cryotherapy for countermovement jump performance at 72h post-exercise. Cold-water immersion also demonstrated lower soreness and higher perceived recovery levels across 24-48h post-exercise

Investigation of the Lignan Content in Extracts from Linum, Callitris and Juniperus Species in Relation to Their In Vitro Antiproliferative Activities

Podophyllotoxin, a lignan still extracted from the rhizomes of Podophyllum hexandrum (Berberidaceae), is the starting molecule for the semisynthesis of widely used anticancer drugs such as etoposide. However, this source is threatened by the over-collection of P. hexandrum. Plants belonging to the Linaceae and Cupressaceae families could be attractive alternative sources with species that contain the lignan podophyllotoxin or its precursors and derivatives. Wild flax species, such as Linum flavum, as well as some Juniperus and Callitris species were investigated for their lignan content, and the in vitro antiproliferative capacity of their extracts was assayed on four tumor cell lines. Some of the lignans were detected by LC-HRMS for the first time in these extracts. In addition, lignans purified from these plants and compounds semisynthesized from commercially available podophyllotoxin were tested in terms of their in vitro antiproliferative activity. The genus Juniperus was the most promising given its in vitro antiproliferative effects, which were also observed with extracts from L. flavum and Callitris species. The in vitro antiproliferative effect of the plant extracts studied here appears to correlate well with the contents of the aryltetralin lignan podophyllotoxin and its glycoside as well as with deoxypodophyllotoxin and 6-methoxypodophyllotoxin. The strongest correlation between the lignan content of the extracts and the antiproliferative activity was observed for 6-methoxypodophyllotoxin. Regarding the possibility of producing large renewable amounts of 6-methoxypodophyllotoxin, this molecule could be of interest to produce new anticancer drugs and to bypass the resistance mechanisms against podophyllotoxin-derived drugs.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Quantum advantage in a spintronic engine with coherently coupled ultrafast strokes using molecular superexchange

Recent theory and experiments have showcased how to harness quantum mechanics to assemble heat/information engines with efficiencies that surpass the classical Carnot limit. So far, implementing work-producing quantum resources has required atomic engines driven by external laser and microwave energy sources We propose a spin electronic implementation that operates autonomously. Our concept heuristically deploys several known quantum resources upon placing a quantum-entangled chain of spin qubits formed by the Co centers of phthalocyanine (Pc) molecules between electron-spin selecting Fe/C60 interfaces. Density functional calculations reveal that transport fluctuation strokes across the interfaces can stabilize spin coherence on the Co paramagnetic centers, which host spin swap engine strokes. Across solid-state vertical molecular nanojunctions, we measure large enduring dc current generation, sizeable output power above room temperature, and two quantum thermodynamical signatures. The Fe/C60 interface's record 89% spin polarization also enables a spintronic feedback and control over the flow and direction of charge current. Beyond these first results, further research into spintronic quantum engines, and retooling the spintronic-based information technology chain7, could help accelerate the transition to clean energy.Comment: