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

Visual Signal Pathway Reorganization in the Cacna1f Mutant Rat Model

PURPOSE. To elucidate the underlying pathologic mechanism of congenital stationary night blindness (CSNB) by examining the characteristics of electrical signal transmission within the inner retinal circuit after Cacna1f gene mutation. METHODS. Retinas isolated from the spontaneous Cacna1f mutant rats or wild-type rats were placed into a recording chamber, with the ganglion cell layer facing the biochip electrode array. The light-driven responses of the retinal ganglion cells (RCGs) were recorded using a multielectrode array (MEA) system. In the electrical stimulus cases, chargebalanced biphasic current pulse trains were generated and applied to the central electrode of MEA to stimulate the RCGs. Chemical compounds were bath-applied through an active perfusion system. The acquired data were further analyzed offline. RESULTS. Typical electrical responses were successfully recorded in the retinas of both wild-type rats and Cacna1f gene mutated rats. In the Cacna1f mutant retinas, the amplitude of the light-induced a-wave was decreased, paralleling the vanished b-wave. The responsive a-wave was not blocked by the application of 100 lM 2-amino-4-phosphobutyric acid. The increased spontaneous firing rate and the decreased robustness of light-driven signaling reflected a loss in the ability of ganglion cells to encode visual signals reliably and economically. Moreover, the ON pathway is somehow disconnected from ganglion cells, whereas OFF pathways may be preferentially selected by the CSNB retinas. In the electrical stimulus cases, the long-latency responses of RGCs evoked by the indirect synaptic inputs from outer layers of retina were weaker in the CSNB rats compared with that of SD rats. CONCLUSIONS. Using MEA recording, we provide evidences of functional changes for visual signal pathway plasticity in the Cacna1f mutated retinas. Our results suggest that the dysfunctions in photoreceptor neurotransmitter release and the loss of signaling efficiency both occur during CSNB, and the latter is possibly reversible. (Invest Ophthalmol Vis Sci

AAV-Mediated Cone Rescue in a Naturally Occurring Mouse Model of CNGA3-Achromatopsia

Achromatopsia is a rare autosomal recessive disorder which shows color blindness, severely impaired visual acuity, and extreme sensitivity to bright light. Mutations in the alpha subunits of the cone cyclic nucleotide-gated channels (CNGA3) are responsible for about 1/4 of achromatopsia in the U.S. and Europe. Here, we test whether gene replacement therapy using an AAV5 vector could restore cone-mediated function and arrest cone degeneration in the cpfl5 mouse, a naturally occurring mouse model of achromatopsia with a CNGA3 mutation. We show that gene therapy leads to significant rescue of cone-mediated ERGs, normal visual acuities and contrast sensitivities. Normal expression and outer segment localization of both M- and S-opsins were maintained in treated retinas. The therapeutic effect of treatment lasted for at least 5 months post-injection. This study is the first demonstration of substantial, relatively long-term restoration of cone-mediated light responsiveness and visual behavior in a naturally occurring mouse model of CNGA3 achromatopsia. The results provide the foundation for development of an AAV5-based gene therapy trial for human CNGA3 achromatopsia

Human gene therapy for RPE65 isomerase deficiency activates the retinoid cycle of vision but with slow rod kinetics

The RPE65 gene encodes the isomerase of the retinoid cycle, the enzymatic pathway that underlies mammalian vision. Mutations in RPE65 disrupt the retinoid cycle and cause a congenital human blindness known as Leber congenital amaurosis (LCA). We used adeno-associated virus-2-based RPE65 gene replacement therapy to treat three young adults with RPE65-LCA and measured their vision before and up to 90 days after the intervention. All three patients showed a statistically significant increase in visual sensitivity at 30 days after treatment localized to retinal areas that had received the vector. There were no changes in the effect between 30 and 90 days. Both cone- and rod-photoreceptor-based vision could be demonstrated in treated areas. For cones, there were increases of up to 1.7 log units (i.e., 50 fold); and for rods, there were gains of up to 4.8 log units (i.e., 63,000 fold). To assess what fraction of full vision potential was restored by gene therapy, we related the degree of light sensitivity to the level of remaining photoreceptors within the treatment area. We found that the intervention could overcome nearly all of the loss of light sensitivity resulting from the biochemical blockade. However, this reconstituted retinoid cycle was not completely normal. Resensitization kinetics of the newly treated rods were remarkably slow and required 8 h or more for the attainment of full sensitivity, compared with \u3c1 h in normal eyes. Cone-sensitivity recovery time was rapid. These results demonstrate\u3edramatic, albeit imperfect, recovery of rod- and cone-photoreceptor-based vision after RPE65 gene therapy

Unimodal productivity-biodiversity relationship along the gradient of multidimensional resources across Chinese grasslands

Resources can affect plant productivity and biodiversity simultaneously and thus are key drivers of their relationships in addition to plant-plant interactions. However, most previous studies only focused on a single resource while neglecting the nature of resource multidimensionality. Here we integrated four essential resources for plant growth into a single metric of resource diversity (RD) to investigate its effects on the productivity-biodiversity relationship (PBR) across Chinese grasslands. Results showed that habitats differing in RD have different PBRs − positive in low-resource habitats, but neutral in medium- and high-resource ones—while collectively, a weak positive PBR was observed. However, when excluding direct effects of RD on productivity and biodiversity, PBR in high-resource habitats became negative, which leads to a unimodal instead of a positive PBR along the RD gradient. By integrating resource effects and changing plant-plant interactions into a unified framework with the RD gradient, our work contributes to uncovering underlying mechanisms for inconsistent PBRs at large scales

Scalable fabrication of hierarchically structured graphite/polydimethylsiloxane composite films for large-area triboelectric nanogenerators and self-powered tactile sensing

Health monitoring, e-skin, and soft robotics call for large-area and robust energy-harvesting strategy to powering their embedded sensors and peripheral electronics. Triboelectric nanogenerator (TENG) is an optimum option to energizing self-powered sensors and self-charging systems. Herein, a large-scale facile and compatiable bar-assisted printing method is presented to achieve hierarchically microstructured polymer composite triboelectric film with good hydrophobicity to improve the electrical output performance and achieve the robustness of TENG. The electrical outputs of the TENG devices are tuned by imparting the graphite fillers into polydimethylsiloxane (PDMS) with optimal concentration. The achieved microstructured graphite/PDMS composite based TENG supplies high and stable short-circuit current of 42 µA, open-circuit voltage of 410 V, and transferred charges of 160 nC under an applied force of 1.2 N, which are sufficient enough to power wearable sensors or charge the energy storage devices. The TENG devices can charge a 2.2 µf capacitor to 1.5 volts within 2 seconds, lighten 30 commercial green LEDs, and drive an electronic watch as well. Self-powered tactile sensing has also been desmonstrated by attaching the TENG devices onto a rubber glove to monitor the process in grasping objects. Furthermore, a large-scale self-powered sensor array is fabricated and utilized to map the spatial pressure distributions. This work not only demonstrates a scable fabrication of the hierarchically microstructured polymer composite films for high-performance TENGs with high electrical outputs, excellent durability and ambient stability, but also brings insight into the development of future cost-effective and self-powered electronics