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Thin film transistors (TFTs) with amorphous zinc tin oxide (ZTO) channel layer were fabricated by a simple and low-cost solution process. The ZTO thin films are highly transparent (>90% transmittance) in the visible region. The ZTO TFTs fabricated at 400 and 500 • C are operated in enhancement mode. The TFT annealed at 500 • C shows a mobility of 14.11 cm 2 V −1 s −1 , a threshold voltage of 1.71 V, a subthreshold slope of 0.4 V dec −1 and an on-off current ratio greater than 10 8. In addition, we investigated the gate bias stability of the TFT. Positive gate bias results in a positive shift of the threshold voltage due to the charge trapping in the channel/dielectric interface.

Autism spectrum disorder (ASD) is a pervasive developmental disorder characterized by three main behavioral symptoms including social deficits, impaired communication, and stereotyped and repetitive behaviors. ASD prevalence shows gender bias to male. Prenatal exposure to valproic acid (VPA), a drug used in epilepsy and bipolar disorder, induces autistic symptoms in both human and rodents. As we reported previously, prenatally VPA-exposed animals at E12 showed impairment in social behavior without any overt reproductive toxicity. Social interactions were not significantly different between male and female rats in control condition. However, VPA-exposed male offspring showed significantly impaired social interaction while female offspring showed only marginal deficits in social interaction. Similar male inclination was observed in hyperactivity behavior induced by VPA. In addition to the ASD-like behavioral phenotype, prenatally VPA-exposed rat offspring shows crooked tail phenotype, which was not different between male and female groups. Both male and female rat showed reduced GABAergic neuronal marker GAD and increased glutamatergic neuronal marker vGluT1 expression. Interestingly, despite of the similar increased expression of vGluT1, post-synaptic marker proteins such as PSD-95 and a-CAMKII expression was significantly elevated only in male offspring. Electron microscopy showed increased number of post-synapse in male but not in female at 4 weeks of age. These results might suggest that the altered glutamatergic neuronal differentiation leads to deranged post-synaptic maturation only in male offspring prenatally exposed to VPA. Consistent with the increased post-synaptic compartment, VPA-exposed male rats showed higher sensitivity to electric shock than VPA-exposed female rats. These results suggest that prenatally VPA-exposed rats show the male preponderance of ASD-like behaviors including defective social interaction similar to human autistic patients, which might be caused by ectopic increase in glutamatergic synapses in male rats.

Imbalance in excitatory/inhibitory signal in the brain has been proposed as one of the main pathological features in autism spectrum disorders, although the underlying cellular and molecular mechanism is unclear yet. Because excitatory/inhibitory imbalance can be induced by aberration in glutamatergic/GABAergic neuronal differentiation, we investigated the mechanism of dysregulated neuronal differentiation between excitatory and inhibitory neurons in the embryonic and postnatal brain of prenatally valproic acid-exposed rat offspring, which is often used as an animal model of autism spectrum disorders. Transcription factor Pax6, implicated in glutamatergic neuronal differentiation, was transiently increased in embryonic cortex by valproate exposure, which resulted in the increased expression of glutamatergic proteins in postnatal brain of offspring. Chromatin immunoprecipitation showed increased acetylated histone binding on Pax6 promoter region, which may underlie the transcriptional up-regulation of Pax6. Other histone deacetylase (HDAC) inhibitors including TSA and SB but not valpromide, which is devoid of HDAC inhibitor activity, induced Pax6 up-regulation. Silencing Pax6 expression in cultured rat primary neural progenitor cells demonstrated that up-regulation of Pax6 plays an essential role in valproate-induced glutamatergic differentiation. Blocking glutamatergic transmission with MK-801 or memantine treatment, and to a lesser extent with MPEP treatment, reversed the impaired social behaviors and seizure susceptibility of prenatally valproate-exposed offspring. Together, environmental factors may contribute to the imbalance in excitatory/inhibitory neuronal activity in autistic brain by altering expression of transcription factors governing glutamatergic/GABAergic differentiation during fetal neural development, in conjunction with the genetic preload.

Transparent thin-film transistors ͑TTFTs͒ with an indium-zinc oxide ͑IZO͒ active layer by the solution-processed deposition method were fabricated and their TFT characterization was examined. Solution-processed IZO thin films were amorphous and highly transparent with Ͼ90% transmittance in the visible region with an optical bandgap of 3.1 eV. Spin-coated IZO TTFTs were operated in depletion mode and showed a field-effect mobility as high as 7.3 cm 2 /V s, a threshold voltage of 2.5 V, an on/off current ratio greater than 10 7 , and a subthreshold slope of 1.47 V/decade. Metal-oxide thin films have been traditionally used as insulators, dielectrics, and conductors in ͑opto͒electronic devices. Recently, metal-oxide thin films have been intensively studied to be applied as transparent semiconducting active layers in transparent thin-film transistors ͑TTFTs͒. Transparent oxide semiconductors ͑TOSs͒ have many advantages compared to silicon or organic semiconductors. TOSs are transparent in the visible region due to their large bandgap and have environmental stability and high field-effect mobility comparable to that of polycrystalline silicon. 1,2 Many TOSs such as ZnO, 3,4 zinc-tin oxide ͑ZTO͒, 5,6 indium-zinc oxide ͑IZO͒, 7-9 and indium-gallium-zinc oxide ͑IGZO͒ 2,10,11 have been reported for transparent active-channel materials in TTFTs. Several TTFTs using TOSs 12,13 and even fully transparent flexible structures 3,14 have been reported. TTFTs based on TOSs are considered to be an alternative to amorphous Si TFTs. However, TOSs are generally prepared by vacuum-deposition methods such as rf magnetron sputtering and pulsed laser deposition. Vacuum-deposition methods require expensive equipment and result in high manufacturing costs.Solution-processed thin-film deposition methods could offer many advantages such as simplicity, low cost, and high throughput that enable the fabrication of high-performance and low-cost electronics. In addition, solution-processed deposition methods such as screen printing, inkjet printing, and imprinting offer the possibility of the direct patternability of TOS thin films which could replace the conventional photolithographic technique. Recently, ZnO, 15-17 ZTO, 18 and IZO-based 19 TTFTs fabricated by solution-processed deposition using metallorganic or metal halide precursors in various solvents were reported to have high mobility up to ϳ16 cm 2 /V s and to give direct patternability. However, in the case of using metal chloride as precursors, the presence of chloride ions during heattreatment of the film is unfavorable under certain circumstances. In addition, TTFTs fabricated by solution-processed deposition showed high off currents and a low on/off current ratio compared to the vacuum-deposited TTFTs.In this article, we report the amorphous IZO semiconductor thin films fabricated by solution process under ambient air conditions using metal acetates as precursors and the performance of TTFTs with an amorphous IZO active layer. Spin-coated IZO thin film was uniform, highly transparent...