683 research outputs found
The impact of pension insurance types on the health of older adults in China: a study based on the 2018 CHARLS data
IntroductionPension insurance is an essential safeguard for the quality of life and health of older adults because it provides a stable and dependable source of income after retirement. China has constructed a multi-level social security system to accommodate the diverse needs of older adults, and offers various levels of pension insurance to maximize their interests.MethodsThis study uses propensity score matching and ordinary least squares techniques to analyze 7,359 data from the 2018 China Health and Retirement Longitudinal Study (CHARLS) in order to explore the relationship between different pension insurance categories and the health of older individuals.ResultsThe research findings reveal that advanced insurances greatly benefit the health of older adults more than basic pension insurances, and the findings pass the robustness test. In addition, the effect was found to be heterogeneous, depending on the location of retirement and the marital status of older adults.Our findings suggest that both material and non-material consumption may be potential mechanisms by which pension insurance affects the health of older adults, providing new evidence for the causal mechanism between pension insurance and the health of older adults.DiscussionThis study expands the scope of research on the health effects of pension insurance by covering a large representative sample across the country. The results show the important impact of the level of pension insurance on the health of older adults and can contribute to the development of social policies to promote the physical and mental health of older adults
Fabrication and characterization of iron pnictide wires and bulk materials through the powder-in-tube method
The recent discovery of superconductivity in the iron based superconductors
with very high upper critical fields presents a new possibility for practical
applications, but fabricating fine-wire is a challenge because of mechanically
hard and brittle powders and the toxicity and volatility of arsenic. In this
paper, we report the synthesis and the physical characterization of iron
pnictide wires and bulks prepared by the powder-in-tube method (PIT). A new
class of high-Tc iron pnictide composite wires, such as LaFeAsO1-xFx,
SmFeAsO1-xFx and Sr1-xKxFeAs, has been fabricated by the in situ PIT technique
using Fe, Ta and Nb tubes. Microscopy and x-ray analysis show that the
superconducting core is continuous, and retains phase composition after wire
drawing and heat treatment. Furthermore, the wires exhibit a very weak Jc-field
dependence behavior even at high temperatures. The upper critical field Hc2(0)
value can exceed 100 T, surpassing those of MgB2 and all the low temperature
superconductors and indicating a strong potential for applications requiring
very high field. These results demonstrate the feasibility of producing
superconducting pnictide composite wire. We also applied the one step PIT
method to synthesize the iron-based bulks, due to its convenience and safety.
In fact, by using this technique, we have successfully discovered
superconductivity at 35 K and 15 K in Eu0.7Na0.3Fe2As2 and SmCoFeAsO compounds,
respectively. These clearly suggest that the one-step PIT technique is unique
and versatile and hence can be tailored easily for other rare earth derivatives
of novel iron-based superconductors.Comment: Review for the special issue of Physica C on iron-based pnictide
superconductor
Superconductivity induced by doping Ru in SrFe2-xRuxAs2
Using one-step solid state reaction method, we have successfully synthesized
the superconductor SrFe1-xRuxAs. X-ray diffraction indicates that the material
has formed the ThCr2Si2-type structure with a space group I4/mmm. The
systematic evolution of the lattice constants demonstrates that the Fe ions are
successfully replaced by the Ru. By increasing the doping content of Ru, the
spin-density-wave (SDW) transition in the parent compound is suppressed and
superconductivity emerges. The maximum superconducting transition temperature
is found at 13.5 K with the doping level of x = 0.7. The temperature dependence
of DC magnetization confirms superconducting transitions at around 12 K. Our
results indicate that similar to non-isoelectronic substitution, isoelectronic
substitution contributes to changes in both the carrier concentration and
internal pressure, and superconductivity could be induced by isoelectronic
substitution.Comment: 14 pages, 4 figure
Effect of hydrogen sulfide on PC12 cell injury induced by high ATP concentration
Purpose: To investigate the potential protective effect of hydrogen sulfide against neural cell damage induced by a high-concentration of adenosine triphosphate (ATP).Methods: PC12 cells were incubated with ATP in order to induce cell damage. The extracellular level of H2S and protein expression of cystathionine-β-synthase (CBS) were determined. The PC12 cells pretreated with NaHS, aminooxyacetic acid (AOAA) and KN-62, prior to further incubation with ATP, and the effect of the treatments on cell viability was investigated.Results: High-concentration ATP induced cell death in PC12 cells, and this was accompanied by markedly increased contents of extracellular H2S and CBS expression (p < 0.05). The ATP-induced cytotoxicity was significantly compromised after pretreatment with H2S. (p < 0.05). The viability of PC12 cells pretreated with NaHS and AOAA was significantly higher than that of PC12 cells treated with ATP alone. In addition, the viability of ATP-treated PC12 cells was further markedly increased after pretreatment with NaHS and KN-62 (p < 0.05).Conclusion: ATP induced a concentration- and time-dependent cytotoxicity in PC12 cells via theendogenous H2S/CBS system. Supplementation with exogenous H2S mitigated the cell damageinduced by high concentration of ATP via a specific mechanism which may be specifically related to P2X7R
Low-temperature synthesis of SmFeAsO0.7F0.3 wires with high transport critical current density
Ag-sheathed SmFeAsO0.7F0.3 (Sm-1111) superconducting wires were prepared by a
one-step solid state reaction at temperatures as low as 850~900C, instead of
commonly used temperatures of 1150~1250C. The X-ray diffraction pattern of the
as-sintered samples is well indexed on the basis of tetragonal ZrCuSiAs-type
structure. We characterized transport critical current density Jc of the
SmFeAsO0.7F0.3 wires in increasing and subsequently decreasing fields, by a
resistive four-probe method. A transport Jc as high as ~1300 A/cm^2 at 4.2 K
and self field has been observed for the first time in Sm-1111 type
polycrystalline superconductors. The Jc also shows a rapid depression in small
applied fields as well as a magnetic-history dependence, indicating weak-linked
grain boundaries. The low-temperature synthesis method can be very beneficial
to fabricating the RE-1111 iron oxynictides in a convenient and safe way.Comment: 12 pages, 3 figure
Large transport critical currents of powder-in-tube Sr0.6K0.4Fe2As2/Ag superconducting wires and tapes
We report significant transport critical currents firstly achieved in
Sr0.6K0.4Fe2As2 wires and tapes with a Tc = 34 K, which were fabricated through
an in-situ powder-in-tube process. Silver was used as a chemical addition as
well as a sheath material. Transport measurements were performed by a standard
four-probe resistive method. All the wire and tape samples have shown transport
properties. Critical current density Jc was enhanced upon silver addition, and
at 4.2 K, a best Jc of ~1200 A/cm^2 (Ic = 9 A) was achieved for 20 % silver
added tapes, which is the highest in iron-based wires and tapes so far. The Jc
is almost field independent between 1 T and 10 T, exhibiting a strong vortex
pinning. Such a high transport critical current density is attributed to the
absence of reaction layer between the silver sheath and superconducting core,
as well as an improved connectivity between grains. We also identify a
weak-link behavior from the creep drop of Jc at low fields and a hysteretic
phenomenon. Finally, we found that compared to Fe, Ta and Nb tubes, Ag was the
best sheath material for the fabrication of high-performance 122 type pnictide
wires and tapes.Comment: 14 pages, 4 figure
Transport properties and anisotropy in rare earth doped CaFe2As2 single crystals with Tc above 40 K
In this paper we report the superconductivity above 40 K in the electron
doping single crystal Ca1-xRexFe2As2 (Re = La, Ce, Pr). The x-ray diffraction
patterns indicate high crystalline quality and c-axis orientation. the
resistivity anomaly in the parent compound CaFe2As2 is completely suppressed by
partial replacement of Ca by rare earth and a superconducting transition
reaches as high as 43 K, which is higher than the value in electron doping
FeAs-122 compounds by substituting Fe ions with transition metal, even
surpasses the highest values observed in hole doping systems with a transition
temperature up to 38 K. The upper critical field has been determined with the
magnetic field along ab-plane and c-axis, yielding the anisotropy of 2~3.
Hall-effect measurements indicate that the conduction in this material is
dominated by electron like charge carriers. Our results explicitly demonstrate
the feasibility of inducing superconductivity in Ca122 compounds via electron
doping using aliovalent rare earth substitution into the alkaline earth site,
which should add more ingredients to the underlying physics of the iron-based
superconductors.Comment: 21 pages, 7 figure
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