With the wide application of organic semiconductors (OSCs), researchers are now grappling with a new challenge: design and synthesize OSCs materials with specific functions to satisfy the requirements of high-performance semiconductor devices. Strain engineering is an effective method to improve the semiconductor material’s carrier mobility, which is fundamentally originated from the rearrangement of the atomic packing model of materials under mechanic stress. Here, we design and synthesize a new OSC material named AZO-BTBT-8 based on high-mobility benzo[b]benzo[4,5]thieno[2,3-d]thiophene (BTBT) as the semiconductor backbone. Octane is employed to increase molecular flexibility and solubility, and azobenzene at the other end of the BTBT backbone provides photoisomerization properties and structural balance. Notably, the AZO-BTBT-8 photoisomerization leads to lattice strain in thin-film devices, where exceptional device performance enhancement is realized. On this basis, a large-scale flexible organic field-effect transistor (OFET) device array is fabricated and realizes high-resolution UV imaging with reversible light response.
The mechanism involved in bringing about post-coital suppression of pheromone production, pheromonostasis, was studied in the noctuid moth Heliothis uirescens. Mating results in a transient suppression in pheromone production, the signal for which appears to originate in the testes and other components of the male's reproductive system. The mating-induced pheromonostasis is due to an ascending signal via the central nervous system that appears to inhibit the release of the pheromonotropin, pheromone biosynthesis activating neuropeptide (PBAN), or other potential pheromonotropic substances, and is not due to a refractoriness in response of the sex pheromone glands to PBAN in the female. A similar mechanism is operative in several species of moths where post-coital pheromonostasis has been observed. Sperm quality is not important for pheromonostasis in H. virescens, because males with apyrene or eupyrene sperm elicit similar pheromonostatic responses. The pheromonostatic activity of the ecdysteroid 20-OH-ecdysone appears to be the result of a direct effect on the sex pheromone glands. 0 1996 Wiley-Liss, Inc.
Occupational exposures to vibration always involve multi-axis vibration. Since human responses to vibration are highly nonlinear and cross-coupled, it is to be expected that excitation in one axis will alter response to vibration in another axis. The purpose of this study was to investigate nonlinearity in the apparent masses of subjects seated without a backrest and exposed to single-axis and dual-axis vertical and fore-and-aft excitation. The driving point apparent masses and cross-axis apparent masses in the two translational directions were measured with twelve subjects exposed to random vibration (0.2 to 20 Hz) in all 15 possible combinations of four vibration magnitudes (0, 0.25, 0.5, or 1.0 ms -2 r.m.s.) in the fore-and-aft and vertical directions. With single-axis excitation (either fore-and-aft or vertical), the median in-line apparent mass exhibited a nonlinear characteristic in which the body softened with increasing magnitude of vibration. With dual-axis excitation, at all magnitudes of vertical excitation the resonance frequency in the vertical apparent mass reduced as the magnitude of fore-and-aft vibration increased, and at all except the greatest magnitude of fore-andaft excitation the resonance frequency in the fore-and-aft apparent mass reduced as the magnitude of vertical vibration increased. The coherency between the fore-and-aft acceleration and the fore-and-aft force was lowered by the addition of vertical excitation, and the coherency between the vertical acceleration and the vertical force was lowered by the addition of fore-and-aft excitation. The nonlinearity evident in both in-line apparent masses was also evident in the crossaxis apparent masses. It is concluded that with dual-axis excitation the fore-and-aft and vertical response of the seated human body is nonlinear, with resonance frequencies decreasing with increasing magnitude of vibration. Consequently, vibration in one axis (either fore-and-aft or vertical) affects the apparent mass of the body measured in the other axis (either vertical or fore-and-aft).
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