Charging Ultra-nanoporous Electrodes with Size-asymmetric Ions Assisted by Apolar Solvent

We develop a statistical theory of charging quasi single-file pores with cations and anions of different sizes as well as solvent molecules or voids. This is done by mapping the charging onto a one-dimensional Blume–Emery–Griffith model with variable coupling constants. The results are supported by three-dimensional Monte Carlo simulations in which many limitations of the theory are lifted. We explore the different ways of enhancing the energy storage which depend on the competitive adsorption of ions and solvent molecules into pores, the degree of ionophilicity and the voltage regimes accessed. We identify new solvent-related charging mechanisms and show that the solvent can play the role of an “ionophobic agent”, effectively controlling the pore ionophobicity. In addition, we demonstrate that the ion-size asymmetry can significantly enhance the energy stored in a nanopore

Magneto-Optical Cooling of Atoms

We propose an alternative method to laser cooling. Our approach utilizes the extreme brightness of a supersonic atomic beam, and the adiabatic atomic coilgun to slow atoms in the beam or to bring them to rest. We show how internal-state optical pumping and stimulated optical transitions, combined with magnetic forces can be used to cool the translational motion of atoms. This approach does not rely on momentum transfer from photons to atoms, as in laser cooling. We predict that our method can surpass laser cooling in terms of flux of ultra-cold atoms and phase-space density, with lower required laser power and reduced complexity

Effects of Community Exercise Therapy on Metabolic, Brain, Physical, and Cognitive Function Following Stroke : A Randomized Controlled Pilot Trial

© The Author(s) 2014.Peer reviewedPostprintPostprin

Detection of radio frequency magnetic fields using nonlinear magneto-optical rotation

We describe a room-temperature alkali-metal atomic magnetometer for detection of small, high frequency magnetic fields. The magnetometer operates by detecting optical rotation due to the precession of an aligned ground state in the presence of a small oscillating magnetic field. The resonance frequency of the magnetometer can be adjusted to any desired value by tuning the bias magnetic field. We demonstrate a sensitivity of $100\thinspace{\rm pG/\sqrt{Hz}\thinspace(RMS)}$ in a 3.5 cm diameter, paraffin coated cell. Based on detection at the photon shot-noise limit, we project a sensitivity of $20\thinspace{\rm pG/\sqrt{Hz}\thinspace(RMS)}$.Comment: 6 pages, 6 figure

Unusually large polarizabilities and "new" atomic states in Ba

Electric polarizabilities of four low-J even-parity states and three low-J odd-parity states of atomic barium in the range $35,600$ to $36,000\ $cm$^{-1}$are investigated. The states of interest are excited (in an atomic beam) via an intermediate odd-parity state with a sequence of two laser pulses. The odd-parity states can be excited due to the Stark-induced mixing with even-parity states. The polarizabilities are measured via direct spectroscopy on the second-stage transition. Several states have tensor and scalar polarizabilities that exceed the values that might be expected from the known energy levels of barium by more than two orders of magnitude. Two of the Stark-induced transitions cannot be identified from the known energy spectrum of barium. The observations suggest the existence of as yet unidentified odd-parity energy states, whose energies and angular momenta are determined in the present experiment. A tentative identification of these states as [Xe]$6s8p ^3P_{0,2}$ is suggested.Comment: 29 pages, 12 figure

Epigallocatechin-3-gallate remodels apolipoprotein A-I amyloid fibrils into soluble oligomers in the presence of heparin

Amyloid deposits of wild-type apolipoprotein A-I (apoA-I), the main protein component of high-density lipoprotein, accumulate in atherosclerotic plaques where they may contribute to coronary artery disease by increasing plaque burden and instability. Using CD analysis, solid-state NMR spectroscopy, and transmission EM, we report here a surprising cooperative effect of heparin and the green tea polyphenol (-)- epigallocatechin-3-gallate (EGCG), a known inhibitor and modulator of amyloid formation, on apoA-I fibrils. We found that heparin, a proxy for glycosaminoglycan (GAG) polysaccharides that co-localize ubiquitously with amyloid in vivo, accelerates the rate of apoA-I formation from monomeric protein and associates with insoluble fibrils. Mature, insoluble apoA-I fibrils bound EGCG (KD = 30 ± 3 μM; Bmax = 40 ± 3 μM), but EGCG did not alter the kinetics of apoA-I amyloid assembly from monomer in the presence or absence of heparin. EGCG selectively increased the mobility of specific backbone and side-chain sites of apoA-I fibrils formed in the absence of heparin, but the fibrils largely retained their original morphology and remained insoluble. By contrast, fibrils formed in the presence of heparin were mobilized extensively by the addition of equimolar EGCG, and the fibrils were remodeled into soluble 20-nm-diameter oligomers with a largely α-helical structure that were nontoxic to human umbilical artery endothelial cells. These results argue for a protective effect of EGCG on apoA-I amyloid associated with atherosclerosis and suggest that EGCG-induced remodeling of amyloid may be tightly regulated by GAGs and other amyloid co-factors in vivo, depending on EGCG bioavailability

Exercise Induces Peripheral Muscle But Not Cardiac Adaptations After Stroke: A Randomized Controlled Pilot Trial

Objective To explore the physiological factors affecting exercise-induced changes in peak oxygen consumption and function poststroke. Design Single-center, single-blind, randomized controlled pilot trial. Setting Community stroke services. Participants Adults (N=40; age>50y; independent with/without stick) with stroke (diagnosed >6mo previously) were recruited from 117 eligible participants. Twenty participants were randomized to the intervention group and 20 to the control group. No dropouts or adverse events were reported. Interventions Intervention group: 19-week (3times/wk) progressive mixed (aerobic/strength/balance/flexibility) community group exercise program. Control group: Matched duration home stretching program. Main Outcome Measures (1) Pre- and postintervention: maximal cardiopulmonary exercise testing with noninvasive (bioreactance) cardiac output measurements; and (2) functional outcome measures: 6-minute walk test; timed Up and Go test, and Berg Balance Scale. Results Exercise improved peak oxygen consumption (18±5 to 21±5mL/(kg⋅min); P<.01) and peak arterial-venous oxygen difference (9.2±2.7 to 11.4±2.9mL of O2/100mL of blood; P<.01), but did not alter cardiac output (17.2±4 to 17.7±4.2L/min; P=.44) or cardiac power output (4.8±1.3 to 5.0±1.35W; P=.45). A significant relation existed between change in peak oxygen consumption and change in peak arterial-venous oxygen difference (r=.507; P<.05), but not with cardiac output. Change in peak oxygen consumption did not strongly correlate with change in function. Conclusions Exercise induced peripheral muscle, but not cardiac output, adaptations after stroke. Implications for stroke clinical care should be explored further in a broader cohort

APC Nb3_3Sn superconductors based on internal oxidation of Nb-Ta-Hf alloys

In the last few years, a new type of Nb$_3$Sn superconducting composite, containing a high density of artificial pinning centers (APC) generated via an internal oxidation approach, has demonstrated a significantly superior performance relative to present, state-of-the-art commercial Nb$_3$Sn conductors. This was achieved via the internal oxidation of Nb-4at.%Ta-1at.%Zr alloy. On the other hand, our recent studies have shown that internal oxidation of Nb-Ta-Hf alloys can also lead to dramatic improvements in Nb$_3$Sn performance. In this work we follow up this latter approach, fabricating a 61-stack APC wire based on the internal oxidation of Nb-4at.%Ta-1at.%Hf alloy, and compare its critical current density (Jc) and irreversibility field (Birr) with APC wires made using Nb-4at.%Ta-1at.%Zr. A second goal of this work was to improve the filamentary design of APC wires in order to improve their wire quality and electromagnetic stability. Our new modifications have led to significantly improved RRR and stability in the conductors, while still keeping non-Cu Jc at or above the FCC Jc specification. Further improvement via optimization of the wire recipe and design is ongoing. Finally, additional work needed to make APC conductors ready for applications in magnets is discussed.Comment: Matches published versio

A Study of the Scintillation Induced by Alpha Particles and Gamma Rays in Liquid Xenon in an Electric Field

Scintillation produced in liquid xenon by alpha particles and gamma rays has been studied as a function of applied electric field. For back scattered gamma rays with energy of about 200 keV, the number of scintillation photons was found to decrease by 64+/-2% with increasing field strength. Consequently, the pulse shape discrimination power between alpha particles and gamma rays is found to reduce with increasing field, but remaining non-zero at higher fields.Comment: 15 pages, 12 figures, accepted by Nuclear Instruments and Methods in Physics Research

"One dimensional" double layer. The effect of size asymmetry of cations and anions on charge-storage in ultranarrow nanopores-an Ising model theory

We develop a statistical mechanical theory of charge storage in quasi-single-file ionophilic nanopores with pure room temperature ionic liquid cations and anions of different size. The theory is mapped to an extension of the Ising model exploited earlier for the case of cations and anions of the same size. We calculate the differential capacitance and the stored energy density per unit surface area of the pore. Both show asymmetry in the dependence on electrode potential with respect to the potential of zero charge, related to the difference in the size of the ions, which will be interesting to investigate experimentally. It also approves the increase of charge storage capacity via obstructed charging, which in these systems emerges for charging nanopores with smaller ions