Down-regulation of miR-29c promotes the progression of oral submucous fibrosis through targeting tropomyosin-1.

BACKGROUND/PURPOSE: Various microRNAs (miRs) have been found to be associated with the development of the precancerous condition of the oral cavity, oral submucous fibrosis (OSF). The expression of miR-29c is dysregulated in oral cancer, but its role in OSF has not been investigated. The purpose of the study is to investigate the functional role of miR-29c and its target in OSF. METHODS: The expression levels of miR-29c in OSF tissues and fibrotic buccal mucosal fibroblasts (fBMFs) were assessed using next-generation sequencing and real-time Polymerase Chain Reaction (PCR) analysis. MiR-29c mimic and inhibitors were employed to examine its functional role of myofibroblast transdifferentiation. In addition, several myofibroblast phenotypes, such as collagen gel contraction and migration were tested, and a luciferase reporter assay was conducted to confirm the relationship between miR-29c and its predicted target, tropomyosin-1 (TPM1). RESULTS: We observed that miR-29c expression was downregulated in fBMFs. fBMFs transfected with miR-29c mimics exhibited reduced migration ability and collagen gel contractility, whereas inhibition of miR-29c in normal BMFs induced the myofibroblast phenotypes. Results from the luciferase reporter assay showed that TPM1 was a direct target of miR-29c and the expression of TPM1 was suppressed in the fBMFs transfected with miR-29c mimics. Besides, we confirmed that the expression of miR-29c was indeed downregulated in OSF specimens. CONCLUSION: MiR-29c seems to exert an inhibitory effect on myofibroblast activation, such as collagen gel contractility and migration ability, via suppressing TPM1. These results suggested that approaches to upregulate miR-29c may be able to ameliorate the progression of OSF.

miR-1246 as a therapeutic target in oral submucosa fibrosis pathogenesis.

BACKGROUND/PURPOSE: Oral submucous fibrosis (OSF) is a precancerous condition of oral cancer with a complex etiology. Our previous work has demonstrated that non-coding RNA miR-1246 contributes to the cancer stemness of oral cancer. In the current study, we sought to investigate the effect of the inhibition of miR-1246 on the oral fibrogenesis. METHODS: The expression levels of miR-1246 in OSF tissues and fibrotic buccal mucosal fibroblasts (fBMFs) were examined by qRT-PCR. Collagen gel contraction and migration assays were conducted to evaluate the myofibroblast activities. The relationship between miR-1246 and type I collagen was assessed and the protein expression of type I collagen was determined by Western blot. RESULTS: MiR-1246 expression was upregulated in both OSF specimen and fBMFs compared to the normal counterparts. Inhibition of miR-1246 successfully suppressed the myofibroblast activities, including collagen gel contractility and migration capacity. Moreover, the expression of miR-1246 was positively correlated with type I collagen and the expression of type I collagen was abrogated by repression of miR-1246. CONCLUSION: MiR-1246 is not only critical to the maintenance of oral stemness but also important to the activation of myofibroblasts. Our results showed that miR-1246 is positively associated with the type I collagen, which may be a downstream effector of miR-1246 and responsible for the fibrosis effect on fBMFs.

Catalytic polymerization of naphthalene by HF/BF3 super acid: an ab initio density functional theory study.

Mesophase pitch fabricated through polymerization of polycyclic aromatic hydrocarbons (PAHs) is highly aromatic and of high quality, and it can be used as a raw material to produce other carbon-based materials. Hydrofluoride/boron trifluoride (HF/BF3) is currently an efficient reagent to catalyze the PAH polymerization to produce mesophase pitch. In this study, density functional theory (DFT) calculations are performed to propose a mechanism for naphthalene catalytic polymerization using HF/BF3. The overall reaction mechanism can be conceptualized as having two stages: activation, followed by polymerization. During activation, HF/BF3 acts a proton donor to activate naphthalene, whose then-protonated form can promote the formation of a C-C bond with another naphthalene molecule via electrophilic addition. We also propose a catalyst recovery pathway, which can stabilize the intermediate products. In the polymerization stage, two types of pathways are proposed, those of chain elongation and intramolecular cyclization. According to the proposed catalytic mechanism in this study, the predicted mesophase product shows highly aliphatic hydrogens, which is consistent with the experimental results. We propose the full catalytic mechanism using DFT calculations. Our results provide a better understanding of how to develop novel and green catalysts, which can replace the HF/BF3 reagent in future applications.

Malignant transformation of oral submucous fibrosis in Taiwan: A nationwide population-based retrospective cohort study.

BACKGROUND: Oral submucous fibrosis (OSF) is one of the well-recognized oral potentially malignant disorders. In this study, we investigated the malignant transformation of OSF in a Taiwanese population. METHODS: A retrospective cohort study was analyzed from Taiwan's National Health Insurance Research Database. A comparison cohort was randomly frequency-matched with the OSF cohort according to age, sex, and index year. Oral leukoplakia (OL) was further stratified to evaluate for the possible synergistic effects of OSF-associated malignant transformation. RESULTS: In this cohort, 71 (9.13%) of 778 cases of OSF were observed to transform into oral cancer. The malignant transformation rate was 29.26-fold in the OSF cohort than in the comparison cohort after adjustment (95% confidence intervals 20.55-41.67). To further stratify with OL, OSF with OL (52.46%; 95% confidence intervals 34.88-78.91) had higher risk of malignant transformation rate than OSF alone (29.84%; 95% confidence intervals 20.99-42.42). The Kaplan-Meier plot revealed the rate free of malignant transformation was significant over the 13-year follow-up period (log-rank test, P<.001). The mean duration of malignant transformation was 5.1, 2.7, and 2.2 years for non-OSF, OSF alone, and OSF with OL, respectively. CONCLUSION: Oral submucous fibrosis patients exhibited a significantly higher risk of malignant transformation than those without OSF. OL could enhance malignant transformation in patients with OSF.

Interaction of electrons with cisplatin and the subsequent effect on DNA damage: a density functional theory study.

Cisplatin, Pt(NH3)2Cl2, is a leading chemotherapeutic agent that has been widely used for various cancers. Recent experiments show that combining cisplatin and electron sources can dramatically enhance DNA damage and the cell-killing rate and, therefore, is a promising way to overcome the side effects and the resistance of cisplatin. However, the molecular mechanisms underlying this phenomenon are not clear yet. By using density functional theory calculations, we confirm that cisplatin can efficiently capture the prehydrated electrons and then undergo dissociation. The first electron attachment triggers a spontaneous departure of the chloride ion, forming a T-shaped [Pt(NH3)2Cl]˙ neutral radical, whereas the second electron attachment leads to a spontaneous departure of ammine, forming a linear [Pt(NH3)Cl](-) anion. We further recognize that the one-electron reduced product [Pt(NH3)2Cl]˙ is extremely harmful to DNA. It can abstract hydrogen atoms from the C-H bonds of the ribose moiety and the methyl group of thymine, which in turn leads to DNA strand breaks and cross-link lesions. The activation energies of these hydrogen abstraction reactions are relatively small compared to the hydrolysis of cisplatin, a prerequisite step in the normal mechanism of action of cisplatin. These results rationalize the improved cytotoxicity of cisplatin by supplying electrons. Although the biological effects of the two-electron reduced product [Pt(NH3)Cl](-) are not clear at this stage, our calculations indicate that it might be protonated by the surrounding water.

Targeting histone deacetylase 9 represses fibrogenic phenotypes in buccal mucosal fibroblasts with arecoline stimulation.

Background/purpose: Oral submucosal fibrosis (OSF) is a premalignant disorder positively associated with betel nut chewing. Recent studies supported the promising benefits of histone deacetylase (HDAC) inhibitors for fibrosis treatment. Here we aim to clarify the pro-fibrogenic role of HDAC9 in regulating OSF. Materials and methods: Healthy and OSF specimens were collected to investigate the clinical significance of HDAC9. Chronic arecoline treatment process was used to induce arecoline-mediated myofibroblasts-related activation of primary buccal mucosa fibroblasts (BMFs). Functional analysis of collagen gel contraction, transwell migration, and wound-healing assays were performed to assess the change in pro-fibrogenic properties of BMFs and fibrotic BMFs (fBMFs). Lentiviral-mediated HDAC9 knockdown was used to verify the role of HDAC9 in the pro-fibrogenic process. Results: We found that arecoline significantly increased the mRNA and protein expression of HDAC9 of BMFs in a dose-dependent manner. Knockdown of HDAC9 in BMFs reversed the strengthened effects of arecoline on collagen gel contraction, cell migration, and wound-healing ability. We further demonstrated that knockdown of HDAC9 in fBMFs significantly attenuated its inherent pro-fibrogenic properties. Furthermore, we confirmed a significantly increased expression of HDAC9 mRNA in OSF compared to normal tissues, which suggested a positive correlation between the up-regulation of HDAC9 and OSF. Conclusion: We demonstrated that silencing of HDAC9 inhibited arecoline-induced activation and inherent pro-fibrogenic properties, suggesting potential therapeutics by targeting HDAC9 in the OSF treatment.

Comparative Study of the Orientation and Order Effects on the Thermoelectric Performance of 2D and 3D Perovskites.

Calcium titanium oxide has emerged as a highly promising material for optoelectronic devices, with recent studies suggesting its potential for favorable thermoelectric properties. However, current experimental observations indicate a low thermoelectric performance, with a significant gap between these observations and theoretical predictions. Therefore, this study employs a combined approach of experiments and simulations to thoroughly investigate the impact of structural and directional differences on the thermoelectric properties of two-dimensional (2D) and three-dimensional (3D) metal halide perovskites. Two-dimensional (2D) and three-dimensional (3D) metal halide perovskites constitute the focus of examination in this study, where an in-depth exploration of their thermoelectric properties is conducted via a comprehensive methodology incorporating simulations and experimental analyses. The non-equilibrium molecular dynamics simulation (NEMD) was utilized to calculate the thermal conductivity of the perovskite material. Thermal conductivities along both in-plane and out-plane directions of 2D perovskite were computed. The NEMD simulation results show that the thermal conductivity of the 3D perovskite is approximately 0.443 W/mK, while the thermal conductivities of the parallel and vertical oriented 2D perovskites increase with n and range from 0.158 W/mK to 0.215 W/mK and 0.289 W/mK to 0.309 W/mK, respectively. Hence, the thermal conductivity of the 2D perovskites is noticeably lower than the 3D ones. Furthermore, the parallel oriented 2D perovskites exhibit more effective blocking of heat transfer behavior than the perpendicular oriented ones. The experimental results reveal that the Seebeck coefficient of the 2D perovskites reaches 3.79 × 102 µV/K. However, the electrical conductivity of the 2D perovskites is only 4.55 × 10-5 S/cm, which is one order of magnitude lower than that of the 3D perovskites. Consequently, the calculated thermoelectric figure of merit for the 2D perovskites is approximately 1.41 × 10-7, slightly lower than that of the 3D perovskites.

Lithium-Ion Dynamic and Storage of Atomically Precise Halogenated Nanographene Assemblies via Bottom-Up Chemical Synthesis.

Graphene has received much scientific attention as an electrode material for lithium-ion batteries because of its extraordinary physical and electrical properties. However, the lack of structural control and restacking issues have hindered its application as carbon-based anode materials for next generation lithium-ion batteries. To improve its performance, several modification approaches such as edge-functionalization and electron-donating/withdrawing substitution have been considered as promising strategies. In addition, group 7A elements have been recognized as critical elements due to their electronegativity and electron-withdrawing character, which are able to further improve the electronic and structural properties of materials. Herein, we elucidated the chemistry of nanographenes with edge-substituted group 7A elements as lithium-ion battery anodes. The halogenated nanographenes were synthesized via bottom-up organic synthesis to ensure the structural control. Our study reveals that the presence of halogens on the edge of nanographenes not only tunes the structural and electronic properties but also impacts the material stability, reactivity, and Li+ storage capability. Further systematic spectroscopic studies indicate that the charge polarization caused by halogen atoms could regulate the Li+ transport, charge transfer energy, and charge storage behavior in nanographenes. Overall, this study provides a new molecular design for nanographene anodes aiming for next-generation lithium-ion batteries.

NS5806 reduces carrageenan-evoked inflammation by suppressing extracellular signal-regulated kinase activation in primary sensory neurons and immune cells.

BACKGROUND: The compound NS5806 attenuates neuropathic pain via inhibiting extracellular signal-regulated kinase (ERK) activation in neuronal somata located at the dorsal root ganglion (DRG) and superficial spinal dorsal horn. NS5806 also reduces the expansion of DRG macrophages and spinal microglia several days after peripheral nerve injury, implying an anti-inflammatory effect. METHODS: To test whether NS5806 inhibits inflammation, as a model we intraplantarly injected carrageenan into a hind paw of the rat. To examine whether NS5806 reduces carrageenan-evoked mechanical allodynia, thermal hyperalgesia, and edema, as well as ERK activation in the nerve fibres, mast cells, and macrophages in the hind paw skin, we used behavioural, immunohistochemical, and cytological methods. RESULTS: NS5806 did not impair motor function, affect basal nociception, or cause edema in naive rats. Six hours after carrageenan injection, mechanical allodynia, thermal hyperalgesia, and edema appeared in the rat's ipsilateral hind paw, and all were reduced by intraplantar co-injection of NS5806. NS5806 suppressed carrageenan-evoked ERK activation in the peripheral axons and somata of L4 DRG neurons, as well as mast cells and macrophages in the paw skin. NS5806 also reduced carrageenan-evoked mast cell degranulation and macrophage proliferation. NS5806 and the ERK pathway inhibitor PD98059 had a similar effect in inhibiting the proliferation of cultured RAW264.7 macrophages. Furthermore, all the in vivo anti-inflammatory effects of NS5806 were similar to those of PD98059. CONCLUSIONS: Acting like an ERK pathway inhibitor, NS5806 reduces inflammation-evoked mechanical allodynia, thermal hyperalgesia, and edema by suppressing ERK activation in primary sensory neurons, mast cells, and macrophages. SIGNIFICANCE: Previous studies show that NS5806 only acts on neurons. This report unveils that NS5806 also acts on immune cells in the skin to exert its anti-inflammatory effects. Since NS5806 is lipid soluble for skin penetration, it suggests that NS5806 could also be developed into an anti-inflammatory drug for external use.

Hybrid Machine Learning-Enabled Potential Energy Model for Atomistic Simulation of Lithium Intercalation into Graphite from Plating to Overlithiation.

Graphite is one of the most widely used negative electrode materials for lithium ion batteries (LIBs). However, because of the rapid growth of demands pursuing higher energy density and charging rates, comprehensive insights into the lithium intercalation and plating processes are critical for further boosting the potential of graphite electrodes. Herein, by utilizing the dihedral-angle-corrected registry-dependent potential (DRIP) (Wen et al., Phys. Rev. B 2018, 98, 235404), the Ziegler-Biersack-Littmark (ZBL) potential (Ziegler and Biersack, Astrophysics, Chemistry, and Condensed Matter; 1985, pp 93-129), and the machine learning-based spectral neighbor analysis (SNAP) potential (Thompson et al., J. Comput, Phys. 2015, 285, 316-330), we have successfully trained a hybrid machine learning-enabled potential energy model capable of simulating a wide spectrum of lithium intercalation scenario from plating to overlithiation. Our extensive atomistic simulations reveal the trapping of intercalated lithium atoms close to the graphite edges due to high hopping barriers, resulting in lithium plating. Furthermore, we report a stable dense graphite intercalation compound (GIC) LiC4 with a theoretical capacity of 558 mAh/g, wherein lithium atoms occupy alternating upper/lower graphene hollow sites with a nearest Li-Li distance of 2.8 Å. Surprisingly, following the same lithium insertion manner would allow the nearest Li-Li distance to be retained until the capacity reaches 845.2 mAh/g, corresponding to a GIC of LiC2.6. Hence, the present study demonstrates that the hybrid machine learning approach could further extend the scope of machine learning energy models, allowing us to investigate the lithium intercalation into graphite over a wide range of intercalation capacity to unveil the underlying mechanisms of lithium plating, diffusion, and discovery of new dense GICs for advanced LIBs with high charging rates and high energy densities.

Decreased trends of using dental amalgam filling for decayed teeth in Taiwan from 1997 to 2013.

Background/purpose: Mercury within dental amalgam has been criticized for the potential toxicity and environmental hazard. Phasing down the use of dental amalgam is the transition for amalgam free dentistry. However, little is known about dental amalgam filling (AMF) in Taiwan. In this study, time trends of AMF were measured by using National Health Insurance Research Database (NHIRD). Materials and methods: A retrospective study was conducted to analyze the AMF data in registered database compiled by Taiwanese NHIRD from 1997 to 2013. The AMF data were further analyzed according to sex, age, and geographic location, respectively. Time trends of dental visits for AMF and medical expenses for AMF were also evaluated. Results: The average annual AMF ratio was 8.965% of nationwide population in Taiwan. The prevalence of AMF was significantly decreased both in male and female from 1997 to 2013 (P for trend <0.0001). The decreased pattern of AMF was found by the age stratification (P for trend <0.0001). The significant fall of AMF was also displayed in six districts (P for trend <0.0001). The number of dental visits were ranged from 821,749 in 1997 to 1,313,734 in 2013. However, time trends of dental visits for AMF were significantly decreased (P for trend <0.0001). The medical expenses for AMF were simultaneous significantly decreased from 1997 to 2013 (P for trend <0.0001). Conclusion: Form the results of this nationwide population-based database, a significant decrease of AMF in Taiwan was observed during past 17 years.

Field-emission stability of hydrothermally synthesized aluminum-doped zinc oxide nanostructures.

The Al-doped ZnO (AZO) nanostructures field-emission arrays (FEAs) were hydrothermally synthesized on AZO/glass substrate. The samples with Al-dosage of 3 at.% show the morphology as nanowires vertically grown on the substrates and a structure of c-axis elongated single-crystalline wurtzite. The good field-emission (i.e., the large anode current and low fluctuation of 15.9%) can be found by AZO nanostructure FEAs with well-designed Al-dosage (i.e., 3 at.%) because of the vertical nanowires with the less structural defects and superior crystallinity. Moreover, the Full width at half maximum (FWHM) of near band-edge emission (NBE) decreased as the increase of annealing temperature, representing the compensated structural defects during oxygen ambient annealing. After the oxygen annealing at 500 degrees C, the hydrothermal AZO nanostructure FEAs revealed the excellent electrical characteristics (i.e., the larger anode current and uniform distribution of induced fluorescence) and enhanced field-emission stability (i.e., the lowest current fluctuation of 5.97%).

Effect of the annealing ambient on the electrical characteristics of the amorphous InGaZnO thin film transistors.

The influence of the thermal annealing on the amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) under different ambient gases has been systematically addressed. The chemical bonding states and transfer characteristics of a-IGZO TFTs show evident dependence on the annealing ambient gas. For the a-IGZO TFTs in the oxygen ambient annealing at 250 degrees C for 30 mins exhibited a maximum field effect mobility (max muFE) of 9.36 cm2/V x s, on/off current ratio of 6.12 x 10(10), and a subthreshold slope (SS) of 0.21 V/decade. Respectively, the as-deposited ones without annealing possess a max muFE of 6.61 cm2/V x s, on/off current ratio of 4.58 x 10(8), and a SS of 0.46 V/decade. In contrast, the a-IGZO TFTs annealed at 250 degrees C for 30 mins in the nitrogen ambient would be degraded to have a max muFE of 0.18 cm2/V x s, on/off current ratio of 2.22 x 10(4), and a SS of 7.37 V/decade, corresponding. It is attributed to the content of the oxygen vacancies, according the x-ray photoelectron spectroscopy (XPS) analyze of the three different samples.

High-performance bottom-gate poly-Si polysilicon-oxide-nitride-oxide-silicon thin film transistors crystallized by excimer laser irradiation for two-bit nonvolatile memory applications.

High-performance bottom-gate (BG) poly-Si polysilicon-oxide-nitride-oxide-silicon (SONOS) TFTs with single grain boundary perpendicular to the channel direction have been demonstrated via simple excimer-laser-crystallization (ELC) method. Under an appropriate laser irradiation energy density, the silicon grain growth started from the thicker sidewalls intrinsically caused by the bottom-gate structure and impinged in the center of the channel. Therefore, the proposed ELC BG SONOS TFTs exhibited superior transistor characteristics than the conventional solid-phase-crystallized ones, such as higher field effect mobility of 393 cm2/V-s and steeper subthreshold swing of 0.296 V/dec. Due to the high field effect mobility, the electron velocity, impact ionization, and conduction current density could be enhanced effectively, thus improving the memory performance. Based on this mobility-enhanced scheme, the proposed ELC BG SONOS TFTs exhibited better performance in terms of relatively large memory window, high program/erase speed, long retention time, and 2-bit operation. Such an ELC BG SONOS TFT with single-grain boundary in the channel is compatible with the conventional a-Si TFT process and therefore very promising for the embedded memory in the system-on-panel applications.

The pH sensing characteristics of the extended-gate field-effect transistors of multi-walled carbon-nanotube thin film using low-temperature ultrasonic spray method.

A novel, simple and low-temperature ultrasonic spray method was developed to fabricate the multi-walled carbon-nanotubes (MWCNTs) based extended-gate field-effect transistors (EGFETs) as the pH sensor. With an acid-treated process, the chemically functionalized two-dimensional MWCNT network could provide plenty of functional groups which exhibit hydrophilic property and serve as hydrogen sensing sites. For the first time, the EGFET using a MWCNT structure could achieve a wide sensing rage from pH = 1 to pH = 13. Furthermore, the pH sensitivity and linearity values of the CNT pH-EGFET devices were enhanced to 51.74 mV/pH and 0.9948 from pH = 1 to pH = 13 while the sprayed deposition reached 50 times. The sensing properties of hydrogen and hydroxyl ions show significantly dependent on the sprayed deposition times, morphologies, crystalline and chemical bonding of acid-treated MWCNT. These results demonstrate that the MWCNT-EGFETs are very promising for the applications in the pH and biomedical sensors.

Field emission properties of carbon nanotube arrays on the thickness-controlled flexible substrate by the pattern transfer process.

A technigal with the polydimethylsiloxane (PDMS) solution infiltrated into the SiOx-coated CNTAs has been utilized to directly transfer the CNTAs away from the silicon substrate. The oxide coating layer was utilized to protect the morpholgy of as-grown patterned vertical aligmed carbon nanotube (CNTs) arrays. The high density plasma reactive ions etching (HDP-RIE) system was used to make the CNTs emerge from the surface of the flexible substrate and modify the crystallines of CNTs. After the protecting oxide was HDP-RIE-processed for 8 min, the emission current properties were enhanced to be 1.03 V/microm and 1.43 V/microm, respectively, for the turn-on field and the threshold field, as compared with 1.25 V/microm and 1.59 V/microm for the as-grown CNTs, accordingly. The Field Emission (FE) enhancement after dry etching could be attributed to the open-ended structures and better crystalline.

High-performance ZnO thin-film transistors with location-controlled crystal grains fabricated by low-temperature hydrothermal method.

In this paper, high-performance bottom-gate (BG) thin-film transistors (TFTs) with zinc oxide (ZnO) artificially location-controlled lateral grain growth have been prepared via low-temperature hydrothermal method. For the proper design of source/drain structure of ZnO/Ti/Pt thin films, the grains can be laterally grown from the under-cut ZnO beneath the Ti/Pt layer. Consequently, the single one vertical grain boundary perpendicular to the current flow will be produced in the channel region as the grown grains from the source/drain both sides are impinged. As compared with the conventional sputtered ZnO BG-TFTs, the proposed location-controlled hydrothermal ZnO BG-TFTs (W/L = 250 microm/10 microm) demonstrated the higher field-effect mobility of 6.09 cm2/V x s, lower threshold voltage of 3.67 V, higher on/off current ratio above 10(6), and superior current drivability, reflecting the high-quality ZnO thin films with less grain boundary effect in the channel region.

The effects of nanometal-induced crystallization on the electrical characteristics of bottom-gate poly-Si thin-film transistors.

The effects of active layer thickness and device dimensions on nanometal-induced crystallization (nano-MIC) were studied to determine the electrical characteristics of the polycrystalline silicon (poly-Si) thin-film transistors (TFTs) with bottom-gate structures. The nano-MIC poly-Si film was obtained via deposition of a 0.4-nm-thick Ni film on the amorphous silicon layer and subsequent annealing at 550 degrees C for 0.5 to 8 h. The EDS revealed a approximately 0.1% Ni concentration in the poly-Si film. The cross-sectional TEM image shows the vertical-grain growth mechanism, where the bottom side of the grain exhibits a larger crytalline area than the top side. Therefore, the field effect mobility of the bottom-gate poly-Si TFTs increases with increased active-amorphous-silicon (a-Si) thickness. Furthermore, the mobility increases when the device dimensions are scaled down. A mechanism for explaining such phenomenon in relation to the nano-MIC bottom-gate poly-Si TFTs was also proposed.

Effect of oxygen annealing on the ultraviolet photoresponse of P-NiO-nanoflower/n-ZnO-nanowire heterostructures.

A transparent ultraviolet (UV) sensor using nanoheterojunctions (NHJs) composed of p-type NiO nanoflowers (NFs) and n-type ZnO nanowires (NWs) was prepared through a sequential low-temperature hydrothermal-growth process. The devices that were annealed in an oxygen (O2) ambient exhibited better rectification behavior (I forward/I reverse = 427), a lower forward threshold voltage (V(th) = 0.98 V), a lower leakage current (1.68 x 10(-5) A/cm2), and superior sensitivity (I uv/I dark = 57.8; I visible/I dark = 1.25) to UV light (lambda = 325 nm) than the unannealed devices. The remarkably improved device performances and optoelectronic characteristics of the annealed p-NiO-NF/n-ZnO-NW NHJs can be associated with their fewer structural defects, fewer interfacial defects, and better crystallinity. A stable and repeatable operation of dynamic photoresponse was also observed in the annealed devices. The excellent sensitivity and repeatable photoresponse to UV light of the hydrothermally grown p-NiO-NF/n-ZnO-NW NHJs annealed in a suitable O2 ambient indicate that they can be applied to nano-integrated optoelectronic devices.

Field-emission characteristics of Al-doped ZnO nanostructures hydrothermally synthesized at low temperature.

The aluminum-doped ZnO (AZO) nanostructures with different Al concentrations were synthesized on AZO/glass substrate via a simple hydrothermal growth method at a temperature as low as 85 degrees C. The morphologies, crystallinity, optical emission properties, and chemical bonding states of AZO nanostructures show evident dependence on the aluminum dosage. The morphologies of AZO nanostructures were changed from vertically aligned nanowires (NWs), and NWs coexisted with nanosheets (NSs), to complete NSs in respect of the Al-dosages of 0-3 at.%, 5 at.%, and 7 at.%, correspondingly. The undoped ZnO and lightly Al-doped AZO (< or = 3 at.%) NWs are single-crystalline wurtzite structure. In contrast, heavily Al-doped AZO sample is polycrystalline. The AZO nanostructure with 3 at.% Al-dosages reveals the optimal crystallinity and less structural defects, reflecting the longest carrier lifetime and highest conductivity. Consequently, the field-emission characteristics of such an AZO emitter can exhibit the higher current density, larger field-enhancement factor (beta) of 3131, lower turn-on field of 2.17 V/microm, and lower threshold field of 3.43 V/microm.