Long-Term Cold Acclimation Extends Survival Time at 0°C and Modifies the Metabolomic Profiles of the Larvae of the Fruit Fly Drosophila melanogaster

Drosophila melanogaster is a chill-susceptible insect. Previous studies on this fly focused on acute direct chilling injury during cold shock and showed that lower lethal temperature (LLT, approximately -5°C) exhibits relatively low plasticity and that acclimations, both rapid cold hardening (RCH) and long-term cold acclimation, shift the LLT by only a few degrees at the maximum.We found that long-term cold acclimation considerably improved cold tolerance in fully grown third-instar larvae of D. melanogaster. A comparison of the larvae acclimated at constant 25°C with those acclimated at constant 15°C followed by constant 6°C for 2 d (15°C→6°C) showed that long-term cold acclimation extended the lethal time for 50% of the population (Lt(50)) during exposure to constant 0°C as much as 630-fold (from 0.137 h to 86.658 h). Such marked physiological plasticity in Lt(50) (in contrast to LLT) suggested that chronic indirect chilling injury at 0°C differs from that caused by cold shock. Long-term cold acclimation modified the metabolomic profiles of the larvae. Accumulations of proline (up to 17.7 mM) and trehalose (up to 36.5 mM) were the two most prominent responses. In addition, restructuring of the glycerophospholipid composition of biological membranes was observed. The relative proportion of glycerophosphoethanolamines (especially those with linoleic acid at the sn-2 position) increased at the expense of glycerophosphocholines.Third-instar larvae of D. melanogaster improved their cold tolerance in response to long-term cold acclimation and showed metabolic potential for the accumulation of proline and trehalose and for membrane restructuring

Relation between Current Transfer Length and Stability of Fe/MgB2MgB_2 and Fe/Nb/MgB2MgB_2 Conductors

This paper treats and confronts the stability of two different composite $MgB_2$ superconductors and searches for relation between the current transfer length and maximum heat flux that conductor can withstand in operational DC regime. It was found that the iron sheathed wire behave more stably than tape-like conductor with outer iron sheath and inner niobium barrier

Properties of doped ex and in situ MgB2 multifilament superconductors

7 pages, 11 figures, 1 table.Four-filament ex and in situ MgB2 wires were prepared with the rectangular wire-in-tube (RWIT) technique. Based on experience with single-core wires, 10 wt% of W was added to the ex situ and 10 wt% of SiC to the in situ powders, which were packed into Fe and Nb/AgMg tubes, respectively, and two-axially rolled into composite conductors. The ex and in situ conductors are compared in terms of field-dependent transport critical current density, effects of filament size reduction and twisting, mechanical behaviour and thermal stability.This work was supported by the Science and Technology Assistance Agency under the contract number APVT-51-029902, and by the EU FP6 contract number NMP3-CT2004-505724. Authors would like to thank T Holúbek for the I–V characteristic measurements.Peer reviewe

Stability of multi-core MgB2/Ti/Cu/SS wires

Stability of 19-filaments MgB2/Ti/Cu/SS wires carrying the transport currents has been examined. Properties of two identical wires annealed at 600 °C/2.5 h and 800 °C/0.5 h were compared. It was found that annealing conditions influence not only the current carrying capacity of MgB2 filaments but also affect the inter-diffusion at Ti/Cu and Cu/SS interfaces, which is worsening the electrical and thermal conductivities of composite elements. Consequently, differences in wire's resistances and I-V quenches were measured, which are correlating well with experimentally estimated minimum quench energy and normal zone propagation velocity. © 2010 Elsevier Ltd. All rights reserved.This work was supported by the Slovak Scientific Agency under the Project APVV-0398-07 and VEGA 2/0037/09 and by the Spanish Ministry of Education and Science, MAT2008-05983-C03-01.Peer Reviewe

Properties of doped ex and in situ MgB2 multifilament superconductors

7 pages, 11 figures, 1 table.Four-filament ex and in situ MgB2 wires were prepared with the rectangular wire-in-tube (RWIT) technique. Based on experience with single-core wires, 10 wt% of W was added to the ex situ and 10 wt% of SiC to the in situ powders, which were packed into Fe and Nb/AgMg tubes, respectively, and two-axially rolled into composite conductors. The ex and in situ conductors are compared in terms of field-dependent transport critical current density, effects of filament size reduction and twisting, mechanical behaviour and thermal stability.This work was supported by the Science and Technology Assistance Agency under the contract number APVT-51-029902, and by the EU FP6 contract number NMP3-CT2004-505724. Authors would like to thank T Holúbek for the I–V characteristic measurements.Peer reviewe

Thermal conductivities and thermal runaways of superconducting MgB₂ wires stabilized by an Al + Al₂O₃ sheath

This paper presents a study of the thermal transport properties of extra-light MgB2/Ti/Al + Al2O3 composite wires. The longitudinal thermal conductivity has been investigated as a function of temperature and magnetic field on wires differing only by an outer Al + Al2O3 sheath. The correlation between the thermal transport properties, the microstructure of the Al + Al2O3 sheath and the Al/Ti interface reactions provide important information for these thermally stabilized extra-light superconductors. The thermal runaways observed by the current–voltage characteristics of MgB2/Ti/Al + Al2O3 wires correlate well with the conductor's temperature affected by the thermal conductivity and the resistance of the outer sheath

MgB2 cables made of thin wires manufactured by IMD process

This paper presents the properties of cables made of thin MgB2 wires with different sheaths manufactured by IMD process. Strong effect of the outer sheath on the J e(B) performance was observed and the best properties were obtained for the strongest Cu sheath. It was found that the transversal and longitudinal cables uniformity affects the critical currents in MgB2 wires made by IMD considerably. We have analyzed the quench dynamics in Rutherford cables with Al + 1.5%Al2O3 sheath, when subjected to heat disturbances. Quench triggered in the strands in direct contact with the heater, observing important delays in quench development among strands. Low AC losses were measured for the extra-light Rutherford cable with Ti barrier and Al + 1.5%Al2O3 sheath due to an increased barrier resisitivity and surface Al sheath oxidation, which reduces coupling current loss component effectivelly.This work was supported by the Slovak Scientific Agency under projects APVV-18-0271, APVV-14-0719 and VEGA 2/0140/19. The authors acknowledge the financial support from MINECO-AEI-FEDER (project ENE2017-83669-C4-1) and from Gobierno de Aragon ‘Construyendo Europa desde Aragon (research group T54_17 R). Authors also would like to acknowledge the use of Servicio General de Apoyo a la Investigacion-SAI, Universidad de Zaragoza.Peer reviewe