Mapping the Sensitive Volume of an Ion-Counting Nanodosimeter

We present two methods of independently mapping the dimensions of the sensitive volume in an ion-counting nanodosimeter. The first method is based on a calculational approach simulating the extraction of ions from the sensitive volume, and the second method on probing the sensitive volume with 250 MeV protons. Sensitive-volume maps obtained with both methods are compared and systematic errors inherent in both methods are quantified.Comment: 27 pages, 8 figures. Submitted to JINST, Jan. 16 200

Experimental study of a transformer with superconducting elements for fault current limitation and energy redistribution

Numerous proposed and developed superconducting fault current limiters and self-limiting transformers limit successfully fault currents but do not provide uninterrupted supplying of consumers. A design investigated in the work combines the functions of a conventional transformer with the functions of fast energy redistribution and fault protection. The device constitutes a transformer containing an additional high-temperature superconducting (HTS) coil short-circuited by a thin film HTS switching element. Fault current limitation and redistribution of the power flow to a standby line are achieved as a result of a fast transition of the superconducting switching element from the superconducting into the normal state. Transient and steady-state characteristics were experimentally investigated. A mathematical model of the device operation was proposed, and the calculated results were found to be in good agreement with the experimental data. The application field and basic requirements to such devices were discussed and it was shown that the proposed device meets these requirements.Comment: 15 pages incl. 4 figures. Submitted to "Cryogenics

Characterisation of a track structure imaging detector

The spatial distribution of radiation-induced ionisations in sub-cellular structures plays an important role in the initial formation of radiation damage to biological tissues. Using the nanodosimetry approach, physical characteristics of the track structure can be measured and correlated to DNA damage. In this work, a novel nanodosimeter is presented, which detects positive ions produced by radiation interacting with a gas-sensitive volume in order to obtain a high resolution image of the radiation track structure. The characterisation of the detector prototype was performed and different configurations of the device were tested by varying the detector cathode material and the working gas. Preliminary results show that the ionisation cluster size distribution can be obtained with this approach. Further work is planned to improve the detector efficiency in order to register the complete three-dimensional track structure of ionising radiatio

New and old N=8 superconformal field theories in three dimensions

We show that an infinite family of N=6 d=3 superconformal Chern-Simons-matter theories has hidden N=8 superconformal symmetry and hidden parity on the quantum level. This family of theories is different from the one found by Aharony, Bergman, Jafferis and Maldacena, as well as from the theories constructed by Bagger and Lambert, and Gustavsson. We also test several conjectural dualities between BLG theories and ABJ theories by comparing superconformal indices of these theories.Comment: 16 pages, late

Crystal structure and magnetic properties of highly-coercive Sr[1–x]Gd[x]Fe[12–x]Zn[x]O[19] ferrites

High-coercivity ferrite samples Sr[1–x]Gd[x]Fe[12–x]Zn[x]O]19] (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) with magnetoplumbite structure were prepared from oxides Fe[2]O[3], Gd[2]O[3], ZnO and carbonate SrCO[3] by solid-state ceramic method, the dependence of the unit cell parameters aand con the value of xwas determined. XRD showed that the samples with x >0.1 were not single-phase, and the samples with x > 0.2 contained not only bases phase with the structure of magnetplumbite, but also the a-Fe[2]O[3] and Gd[3]Fe[5]O[12] phases. It was found that increase of the xvalue leads to a slight decrease in the Curie temperature (from 727 K for the basic ferrite SrFe[12]O[19] to 714 K for Sr[1–x]Gd[x]Fe[12–x]Zn[x]O[19] solid solution with x = 0.5). It has been found that at 300 K values of spontaneous magnetization (no) and coercive force (?Hc) of solid solution Sr[0.9]Gd[0.1]Fe[11.9]Zn[0.1]O[19] are respectively 1.3 and 2.3% higher than for the base ferrite SrFe[12]O[19], and values of samples with x > 0.1 of these magnetic properties decreases gradually

Optical and magnetooptical properties of manganese-zinc ferrospinels

The use of optical methods for the investigation of the electronic structure of oxide ferrimagnets is complicated by the large variety of possible types of electron transitions whose energies are close to each other and lie in the near infrared, visible, and near ultraviolet regions of the spectrum. Therefore, for the correct identification of the transitions, it is desirable to apply traditional optical spectroscopy, which permits quantitative evaluation of the transition intensities (oscillator strength), in conjunction with magnetooptical (MO) methods providing information on weak intraconfigurational transitions which are not manifest in ordinary absorption or reflection spectra. © 1984 Plenum Publishing Corporation

Crystal structure, magnetic and electrical properties and thermal expansion of ferrites of the system Sr1–xSmxFe12–xZnxO19 ( x= 0–0.5)

High-coercivity ferrite samples Sr1–xSmxFe12–xZnxO19 (x = 0–0.5) with magnetoplumbite structure were prepared from oxides Fe2O3, Sm2O3, ZnO and carbonate SrCO3by solid-state ceramic method, the dependence of the unit cell parameters aand con the value of x was determined. It was determined that samples of Sr1–xSmxFe12–xZnxO19were single-phased up to x= 0.2, and also contained ?-Fe2O3for x ?0.3 phase, quantity of which gradually increased with increasing xup to 0.5, and small quantities of phases ZnFe2O4and SmFeO3were present in the samples with x= 0.4 and 0.5. The magnetic, electrical properties and thermal expansion of these ferrite samples were studied, the values of specific saturation magnetization (?s ) were determined by magnetic hysteresis loops at 5 and 300 K. It was found that the solid solution Sr0.9Sm0.1Fe11.9Zn0.1O19at 300 K has specific saturation magnetization (?s ) and coercive force (?Hc) respectively by 0.4 and 9.7% higher than the base ferrite SrFe12O19

Nonlinear material and ionic transport through membrane nanotubes

Membrane nanotubes (NTs) and their networks play an important role in intracellular membrane transport and intercellular communications. The transport characteristics of the NT lumen resemble those of conventional solid-state nanopores. However, unlike the rigid pores, the soft membrane wall of the NT can be deformed by forces driving the transport through the NT lumen. This intrinsic coupling between the NT geometry and transport properties remains poorly explored. Using synchronized fluorescence microscopy and conductance measurements, we revealed that the NT shape was changed by both electric and hydrostatic forces driving the ionic and solute fluxes through the NT lumen. Far from the shape instability, the strength of the force effect is determined by the lateral membrane tension and is scaled with membrane elasticity so that the NT can be operated as a linear elastic sensor. Near shape instabilities, the transport forces triggered large-scale shape transformations, both stochastic and periodic. The periodic oscillations were coupled to a vesicle passage along the NT axis, resembling peristaltic transport. The oscillations were parametrically controlled by the electric field, making NT a highly nonlinear nanofluidic circuitry element with biological and technological implications.This work was partially supported by NIGMS of the National Institutes of Health under award R01GM121725, RYC-2014-01419 to A.V.S.; Spanish Ministry of Science, Innovation and Universities grants PGC2018-099971-B-I00 and EUR2019-103830 to A.V.S.; Basque Government grant IT1270-19; and the Ministry of Science and Higher Education of the Russian Federation to P.I.K. and G.T.R

Crystal structure and magnetic properties of Gd1-xLaxMO3 (M= Sc, In, Ga) solid solutions

Gd1–xLaxScO3, Gd1–xLaxInO3and Gd1–xLaxGaO3solid solutions were synthesized by the ceramic method, their crystal structure and magnetic properties were investigated. It has been established that the range of solid solutions Gd1–xLaxScO3(0.0 < х ?1.0), Gd1–xLaxInO3(0.2 ? х ?1.0) and Gd1–xLaxGaO3(0.5 ? х ?1.0) with the structure of orthorhombically distorted perovskite was formed. The effective magnetic moment of the Gd 3+ ion (µef, Gd 3+) for Gd1–xLaxScO3solid solutions with x= 0.10, 0.50 is equal to 7.76 ?В, 7.61 µВ, respectively and it is slightly lower than the theoretical value ?ef. theor, Gd 3+= 7.94 µВ, and for x= 0.75, 0.90 it is practically equal to the theoretical value. For Gd1–xLaxGaO3solid solutions with x= 0.8, 0.9 the effective magnetic moment ?ef, Gd 3+ is 7.90 ?В, 7.99 ?В, respectively, and it is close to the theoretical value 7.94 ?В. For Gd1–xLaxInO3solid solutions the effective magnetic moment ?ef, Gd 3+ varies without certain dependence in the interval from 6.91 ?Вto 7.54 µВand is lower than theoretical value ?эф. теор, Gd 3+