Zero-bias photocurrents in highly-disordered networks of Ge and Si nanowires.

Semiconducting nanowire (NW) devices have garnered attention in self-powered electronic and optoelectronic applications. This work explores and exhibits, for the first time for visible light, clear evidence of the zero-biased optoelectronic switching in randomly dispersed Ge and Si NW networks. The test bench, on which the NWs were dispersed for optoelectronic characterization, was fabricated using a standard CMOS fabrication process, and utilized metal contacts with dissimilar work functions-Al and Ni. The randomly dispersed NWs respond to light by exhibiting substantial photocurrents and, most remarkably, demonstrate zero-bias photo-switching. The magnitude of the photocurrent is dependent on the NW material, as well as the channel length. The photocurrent in randomly dispersed GeNWs was found to be higher by orders of magnitude compared to SiNWs. In both of these material systems, when the length of the NWs was comparable to the channel length, the currents in sparse NW networks were found to be higher than those in dense NW networks, which can be explained by considering various possible arrangements of NWs in these devices.

Sperm-egg interaction is mediated by a sperm-associated body in quail.

The present study describes the holes in the inner vitelline membrane of fertile eggs of the quail Coturnix japonica, which remain after the spermatozoa pass through. It was shown that the light-microscopically observable 'holes' correspond mostly to electron-microscopically defined 'disks', and, to a lesser extent (about 5%), real holes. Immunofluorescent staining of the vitelline membranes with an antiquail ZPC antiserum was used to discriminate the holes from the disks light-microscopically. Over 96% of holes were accompanied by calcium-coated sperm-associated bodies, indicating a close relationship between the two. There was no preferential localization of the disks, holes or sperm-associated bodies in the vitelline membrane around the egg. The sperm-associated bodies bound with the spermatozoa at the posterior end of sperm flagella. Incubation of the inner vitelline membranes, isolated from the largest follicles, with spermatozoa resulted in production only of the disks, whereas the holes (about 9%) were produced when the sperm-associated bodies were added to the system. It was suggested that the sperm-associated bodies assist fertile spermatozoa in binding to the inner vitelline membrane, making holes in the membrane and passing through them in fertile eggs.