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