The cross-sectional morphology of the bulk heterojunction (BHJ) films comprising regio-regular poly(3-hexylthiophene) (rrP3HT) and [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) was observed with transmission electron microscopy (TEM). The cross-sectional TEM images of the BHJ film provide information on the pathways for charge transport through the film thickness. The length scale of the phase separation was obtained from spatial Fourier transform analysis of the TEM images and from calculations of the autocorrelation function.
Müller cells are subtly different in the GFAP(-/-)vim(-/-) mouse retina before detachment. The end foot region of these cells may be structurally reinforced by the presence of the intermediate filament cytoskeleton, and our data suggest a critical role for these proteins in Müller cell reaction to retinal detachment and participation in subretinal gliosis.
Demands for high-performance displays with high pixel density and picture quality are ever increasing.Indium gallium nitride (InGaN)-based micro-LEDs (μLEDs) are suitable for meeting such demands owing to their high e ciency, brightness, and stability. However, the poor yield of the pick-and-place technique, defect repair, and visibility of edge lines between modules limit the applications of μLEDs. Furthermore, the external quantum e ciency (EQE) decreases (<10%) when μLED size is reduced to less than 10 μm for high pixel densities, thereby limiting the luminance. Here, we demonstrate a top-down-processed blue InGaN/GaN multiple-quantum well (MQW) nanorod-LED (nLED) can be made highly e cient as well as become an enabling technology for reducing manufacturing cost of large-screen displays. A pixel array comprising of horizontally-aligned nLEDs between pixel electrodes can be cost-effectively fabricated by applying the dielectrophoretic force to the inkjet-printed nLEDs dispersed in ink solution. To overcome size-dependent EQE reduction problem, we studied the interaction between the GaN surface and the surface passivation layer via various analyses and found that minimizing the point defects created during the passivation process is crucial to manufacturing high-performance nanoscale LEDs. Notably, the sol-gel method is advantageous for the passivation because SiO2 nanoparticles are adsorbed on the GaN surface, thereby minimizing its atomic interactions. The fabricated nLEDs exhibited an EQE of 20.2±0.6%, the highest EQE value ever reported for the LED in the nanoscale. This work opens the way for manufacturing self-emissive nLED displays that can fully meet the industry requirements of high e ciency and brightness and low-power consumption, contributing to energy saving, carbon neutrality and mitigating climate crisis.
The neuropeptide pituitary adenylyl cyclase-activating peptide (PACAP) and one of its receptors (PAC 1 ) are expressed in embryonic neural tube, where they appear to regulate neurogenesis and patterning. We now show that PAC 1 gene expression is also present in neonatal rats in the ventricular and subventricular zones and in the optic chiasm, areas that are rich in oligodendrocyte (OL) progenitors (OLP). Because actions of PACAP on OLP have not been reported, we examined the effects of PACAP on the proliferation of purified OLP in culture and on myelinogenesis in cerebellar slices. Northern analyses on total RNA from purified glial cell subtypes revealed an abundant 7 kb hybridizing transcript in OLP, which was confirmed to correspond to the PAC 1 receptor by reverse transcription-PCR. The presence of this receptor was also corroborated by radioligand binding and cAMP assay. In cultured OL, receptor density decreased during maturation but was partially counterbalanced by the appearance of sites that bound both PACAP and the related peptide vasoactive intestinal peptide. PACAP increased DNA synthesis in OLP cultures almost twofold and increased the bromodeoxyuridine-labeling index in O4-positive OLP. PACAP treatment also resulted in decreased sulfate incorporation into sulfatide in cultures of differentiating OL. The PACAP effect on sulfatide synthesis was fully reproduced in a cerebellar explant model. These findings indicate that PACAP may act at two stages during OL development to (1) stimulate proliferation and (2) delay maturation and/or myelinogenesis.
Pituitary adenylyl cyclase activating peptide (PACAP) has been shown either to stimulate or to inhibit neural cell proliferation depending on the origin of the cell population. We show here that, depending on the presence or absence of fibroblast growth factor-2 (FGF-2, also called basic FGF), PACAP may either stimulate or inhibit DNA synthesis in neural precursors isolated from embryonic day 10.5 mouse hindbrain. In the absence of FGF-2, PACAP stimulated 3H-thymidine incorporation in a dose-dependent manner. This stimulatory action was unaffected by antagonists of protein kinases A and C but was abolished in the presence of the MEK1/2 antagonist PD98059. In contrast, when FGF-2 was present, PACAP inhibited DNA synthesis. This inhibitory action was insensitive to PD98059 but was fully blocked by the protein kinase A (PKA) inhibitor H89. The differential blockades by MEK1/2 and PKA inhibitors indicate that the FGF-2-induced switch in PACAP action on DNA synthesis was accomplished by a change in PACAP signaling pathways. We hypothesize that the actions of PACAP in the specific parts of the developing nervous system are determined in part by the presence or absence of FGFs and other growth factors.
Individual molecular spins are promising quantum states for emerging computation technologies. The “on surface” configuration of molecules in proximity to a magnetic film allows control over the orientations of molecular spins and coupling between them. The stacking of planar molecular spins could favor antiferromagnetic interlayer couplings and lead to pinning of the magnetic underlayer via the exchange bias, which is extensively utilized in ultrafast and high-density spintronics. However, fundamental understanding of the molecular exchange bias and its operating features on a device has not been unveiled. Here, we showed tunable molecular exchange bias and its asymmetrical magnetotransport characteristics on a device by using the metalloporphyrin/cobalt hybrid films. A series of the distinctive molecular layers showcased a wide range of the interfacial exchange coupling and bias. The transport behaviors of the hybrid bilayer films revealed the molecular exchange bias effect on a fabricated device, representing asymmetric characteristics on anisotropic and angle-dependent magnetoresistances. Theoretical simulations demonstrated close correlations among the interfacial distance, magnetic interaction, and exchange bias. This study of the hybrid interfacial coupling and its impact on magnetic and magnetotransport behaviors will extend functionalities of molecular spinterfaces for emerging information technologies.
Correlated transparent conductors (TCs) have attracted great attention because they can overcome the limitations of conventional TCs owing to their high visible transmittance and low sheet resistance. However, the most widely studied TC 3d1 SrVO3 exhibits low ultraviolet transmittance, and the recently investigated TC 4d2 SrMoO3 has low infrared transmittance. Here, it is proposed that the wide transparency range of correlated TCs arises from both high correlation strength and high transition energy from the O‐2p to the transition metal d orbitals. Applying this comprehensive design principle to single‐crystalline correlated metals, it is confirmed that correlated 4d1 SrNbO3 exhibits enhanced ultraviolet–visible–infrared transmittance, with low sheet resistance at room temperature, compared to 3d1 SrVO3 and 4d2 SrMoO3. Spectroscopic ellipsometry, X‐ray photoelectron spectroscopy, and density functional theory calculations reveal that the advantageous properties of 4d1 SrNbO3 can be attributed to high p–d transition energy and moderate correlation effect. The design principle can aid the discovery of additional high‐performance TC materials and further development of correlated TCs.
Heterointerfaces may exhibit unexpected physical properties distinct from intrinsic properties of component materials. In particular, metal–organic interfaces can drive unique interfacial spin moments, which are often called molecular spinterface. Here, van der Waals stacking of molecular layers may lead to variations in the intra/interlayer exchange coupling resulting in multiple ground states, which is highly desired for multifunctional magnetic devices. In this report, the emergence of molecular multispinterface of paramagnetic cobalt‐octaethyl‐porphyrin (CoOEP) layers in a Fe/CoOEP heterostructure is demonstrated through the interfacial layer and a successive antiferromagnetic molecular spin chain. The disentangled interfacial ferromagnetic spins lead to multiple magnetic ground states and behave as additional spin‐dependent scattering centers, as evidenced through the magnetotransport study. In addition, the antiferromagnetic molecule spin chain derives tunable exchange bias, which signifies the dominance of the antiferromagnetic interfacial interaction. Theoretical calculations demonstrate spin configurations of the molecular chain and the antiferromagnetic interfacial coupling through oxygen intermediaries. The development of the molecular multispinterface and controllable exchange bias therein will provide a promising route for the active control of multivalued data processing at the nanoscale.
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