28 research outputs found
Proximity effect at superconducting Sn-Bi2Se3 interface
We have investigated the conductance spectra of Sn-Bi2Se3 interface junctions
down to 250 mK and in different magnetic fields. A number of conductance
anomalies were observed below the superconducting transition temperature of Sn,
including a small gap different from that of Sn, and a zero-bias conductance
peak growing up at lower temperatures. We discussed the possible origins of the
smaller gap and the zero-bias conductance peak. These phenomena support that a
proximity-effect-induced chiral superconducting phase is formed at the
interface between the superconducting Sn and the strong spin-orbit coupling
material Bi2Se3.Comment: 7 pages, 8 figure
Anomalous Cooper pair interference on Bi2Te3 surface
It is believed that the edges of a chiral p-wave superconductor host Majorana
modes, relating to a mysterious type of fermions predicted seven decades ago.
Much attention has been paid to search for p-wave superconductivity in
solid-state systems, including recently those with strong spin-orbit coupling
(SOC). However, smoking-gun experiments are still awaited. In this work, we
have performed phase-sensitive measurements on particularly designed
superconducting quantum interference devices constructing on the surface of
topological insulators Bi2Te3, in such a way that a substantial portion of the
interference loop is built on the proximity-effect-induced superconducting
surface. Two types of Cooper interference patterns have been recognized at low
temperatures. One is s-wave like and is contributed by a zero-phase loop
inhabited in the bulk of Bi2Te3. The other, being identified to relate to the
surface states, is anomalous for that there is a phase shift between the
positive and negative bias current directions. The results support that the
Cooper pairs on the surface of Bi2Te3 have a 2\pi Berry phase which makes the
superconductivity p_x+ip_y-wave-like. Mesoscopic hybrid rings as constructed in
this experiment are presumably arbitrary-phase loops good for studying
topological quantum phenomena.Comment: supplementary material adde
Melatonin ameliorates cisplatin-induced asthenozoospermia via reducing oxidative stress
Background and objective: Cisplatin is an alkylating agent that has
become a first-line therapy for some tumors. However, overproduction of reactive
oxygen species (ROS) by cisplatin can cause male infertility, which can affect
patients’ quality of life. Melatonin, which has the ability to provide resistance
against oxidation, is a potential therapy for male infertility caused by
cisplatin.
Material and methods: Normal human spermatozoa samples were divided
into (i) control group incubated with physiological saline solution; (ii)
cisplatin group incubated with cisplatin; (iii) melatonin group incubated with
melatonin; and (iv) melatonin + cisplatin group incubated with melatonin and
cisplatin. Spermatozoa motility was measured using a computer-aided semen
analysis system. Additionally, we determined spermatozoa apoptosis through
terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling. The
mitochondrial membrane potential (ΔΨm) and levels of ATP, ROS,
and malondialdehyde, as a metabolite of oxidative stress, were measured to study
the mechanism by which melatonin can protect human spermatozoa.
Results: Melatonin improved sperm motility, and decreased apoptosis and
increased the ΔΨm value and level of ATP in sperm. More
importantly, the overproduction of ROS induced by cisplatin was reduced by
melatonin. Furthermore, western blotting revealed that melatonin increased the
expression of antioxidant pathway components nuclear factor erythroid 2-related
factor (Nrf2) and heme oxygenase-1 (HO-1) that was reduced by cisplatin.
Conclusion: Our studies suggested that melatonin might protect human
spermatozoa against the effects of cisplatin through Nrf2/HO-1
Effect of Catalytic Cylinders on Autothermal Reforming of Methane for Hydrogen Production in a Microchamber Reactor
A new multicylinder microchamber reactor is designed on autothermal reforming of methane for hydrogen production, and its performance and thermal behavior, that is, based on the reaction mechanism, is numerically investigated by varying the cylinder radius, cylinder spacing, and cylinder layout. The results show that larger cylinder radius can promote reforming reaction; the mass fraction of methane decreased from 26% to 21% with cylinder radius from 0.25 mm to 0.75 mm; compact cylinder spacing corresponds to more catalytic surface and the time to steady state is decreased from 40 s to 20 s; alteration of staggered and aligned cylinder layout at constant inlet flow rates does not result in significant difference in reactor performance and it can be neglected. The results provide an indication and optimize performance of reactor; it achieves higher conversion compared with other reforming reactors