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1.
Mol Psychiatry ; 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-32015466

RESUMO

Schizophrenia is a complex genetic disorder, the non-Mendelian features of which are likely complicated by epigenetic factors yet to be elucidated. Here, we performed RNA sequencing of peripheral blood RNA from monozygotic twins discordant for schizophrenia, and identified a schizophrenia-associated upregulated long noncoding RNA (lncRNA, AC006129.1) that participates in the inflammatory response by enhancing SOCS3 and CASP1 expression in schizophrenia patients and further validated this finding in AC006129.1-overexpressing mice showing schizophrenia-related abnormal behaviors. We find that AC006129.1 binds to the promoter region of the transcriptional repressor Capicua (CIC), facilitates the interactions of DNA methyltransferases with the CIC promoter, and promotes DNA methylation-mediated CIC downregulation, thereby ameliorating CIC-induced SOCS3 and CASP1 repression. Derepression of SOCS3 enhances the anti-inflammatory response by inhibiting JAK/STAT-signaling activation. Our findings reveal an epigenetic mechanism with etiological and therapeutic implications for schizophrenia.

2.
Opt Lett ; 44(23): 5784-5787, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31774779

RESUMO

We demonstrate enhanced four-wave mixing (FWM) in high-quality factor, high-confinement 4H-SiC microring resonators via continuous-wave FWM. With the large power buildup effect of the microring resonator, -21.7 dBFWM conversion efficiency is achieved with 79 mW pump power. Thanks to the strong light confinement in SiC-on-insulator (SiCOI) waveguides with submicrometer cross-sectional dimensions, a high nonlinear parameter wγ of 7.4±0.9 W-1 m-1 is obtained, from which the nonlinear refractive index (n2) of 4H-SiC is estimated to be (6.0±0.6)×10-19 m2/W at the telecom wavelengths. Besides, we are able to engineer the dispersion of a SiCOI waveguide to achieve 3 dB FWM conversion bandwidth of more than 130 nm. This work represents a step toward enabling all-optical signal processing functionalities using highly nonlinear SiCOI waveguides.

3.
Sci Rep ; 9(1): 16333, 2019 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-31705041

RESUMO

A comprehensive study of surface passivation effect on porous fluorescent silicon carbide (SiC) was carried out to elucidate the luminescence properties by temperature dependent photoluminescence (PL) measurement. The porous structures were prepared using an anodic oxidation etching method and passivated by atomic layer deposited (ALD) Al2O3 films. An impressive enhancement of PL intensity was observed in porous SiC with ALD Al2O3, especially at low temperatures. At temperatures below 150 K, two prominent PL emission peaks located at 517 nm and 650 nm were observed. The broad emission peak at 517 nm was attributed to originate from the surface states in the porous structures, which was supported by X-ray photoelectron spectra characterization. The emission peak at 650 nm is due to donor-acceptor-pairs (DAP) recombination via nitrogen donors and boron-related double D-centers in fluorescent SiC substrates. The results of the present work suggest that the ALD Al2O3 films can effectively suppress the non-radiative recombination for the porous structures on fluorescent SiC. In addition, we provide the evidence based on the low-temperature time-resolved PL that the mechanism behind the PL emission in porous structures is mainly related to the transitions via surface states.

4.
ACS Omega ; 4(13): 15488-15495, 2019 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-31572849

RESUMO

The excitation-dependent photoluminescence quantum yield (PL-QY) of strong n-type nitrogen-boron codoped 6H fluorescent silicon carbide (f-SiC) at room temperature is experimentally determined for the first time. The PL-QY measurements are realized by an integrating sphere system based on a classical two-measurement approach. In particular, in accordance to the difference between our in-lab setup and the standard setup of the two-measurement approach, we have technically modified the experimental design, the data processing algorithm, and the estimation of relative uncertainty. The measured highest PL-QY of f-SiC samples is found to reach above 30%. We compare the PL-QYs at a certain excitation power of all f-SiC samples by considering their intrinsic defect densities. Finally, the evolution of the excitation power-dependent PL-QY of f-SiC is attributed to both band-to-band and impurity-assisted Auger recombination.

5.
Opt Express ; 27(9): 13053-13060, 2019 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-31052835

RESUMO

Silicon carbide (SiC) exhibits promising material properties for nonlinear integrated optics. We report on a SiC-on-insulator platform based on crystalline 4H-SiC and demonstrate high-confinement SiC microring resonators with sub-micron waveguide cross-sectional dimensions. The Q factor of SiC microring resonators in such a sub-micron waveguide dimension is improved by a factor of six after surface roughness reduction by applying a wet oxidation process. We achieve a high Q factor (73,000) for such devices and show engineerable dispersion from normal to anomalous dispersion by controlling the waveguide cross-sectional dimension, which paves the way toward nonlinear applications in SiC microring resonators.

6.
Materials (Basel) ; 11(12)2018 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-30518146

RESUMO

Van der Waals epitaxy (vdWE) has drawn continuous attention, as it is unlimited by lattice-mismatch between epitaxial layers and substrates. Previous reports on the vdWE of III-nitride thin film were mainly based on two-dimensional (2D) materials by plasma pretreatment or pre-doping of other hexagonal materials. However, it is still a huge challenge for single-crystalline thin film on 2D materials without any other extra treatment or interlayer. Here, we grew high-quality single-crystalline AlN thin film on sapphire substrate with an intrinsic WS2 overlayer (WS2/sapphire) by metal-organic chemical vapor deposition, which had surface roughness and defect density similar to that grown on conventional sapphire substrates. Moreover, an AlGaN-based deep ultraviolet light emitting diode structure on WS2/sapphire was demonstrated. The electroluminescence (EL) performance exhibited strong emissions with a single peak at 283 nm. The wavelength of the single peak only showed a faint peak-position shift with increasing current to 80 mA, which further indicated the high quality and low stress of the AlN thin film. This work provides a promising solution for further deep-ultraviolet (DUV) light emitting electrodes (LEDs) development on 2D materials, as well as other unconventional substrates.

7.
Materials (Basel) ; 11(12)2018 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-30486245

RESUMO

High density of defects and stress owing to the lattice and thermal mismatch between nitride materials and heterogeneous substrates have always been important problems and limit the development of nitride materials. In this paper, AlGaN light-emitting diodes (LEDs) were grown directly on a single-layer graphene-covered Si (111) substrate by metal organic chemical vapor deposition (MOCVD) without a metal catalyst. The nanorods was nucleated by AlGaN nucleation islands with a 35% Al composition, and included n-AlGaN, 6 period of AlGaN multiple quantum wells (MQWs), and p-AlGaN. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) showed that the nanorods were vertically aligned and had an accordant orientation along the [0001] direction. The structure of AlGaN nanorod LEDs was investigated by scanning transmission electron microscopy (STEM). Raman measurements of graphene before and after MOCVD growth revealed the graphene could withstand the high temperature and ammonia atmosphere in MOCVD. Photoluminescence (PL) and cathodoluminescence (CL) characterized an emission at ~325 nm and demonstrated the low defects density in AlGaN nanorod LEDs.

8.
Sci Rep ; 8(1): 13030, 2018 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-30158626

RESUMO

We derive full-vectorial nonlinear propagation equations of dual-pumped four-wave mixing in straight waveguides, which are valid in characterizing the one-to-six wavelength multicasting. Special attention is paid to the resulting idler wavelengths and their conversion efficiency, which enables the optimization of the experimental designs, including the incident wavelength and the power of pumps and signal. We validate the model by comparing the numerical simulation to the experimental measurement in a silicon-on-insulator waveguide, for the first time to our best knowledge, and achieve a good agreement. We further derive the general form of the proposed model for the case of using multiple,pumps, which holds a potential to numerically predict the performance of complex wavelength multicasting, and essentially guide the waveguide designs.

9.
Opt Lett ; 43(9): 2201-2203, 2018 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-29714789

RESUMO

In this Letter, we propose a new method for auto-focusing and reconstruction without defocus noise in optical scanning holography. By using a connected domain (CD) to calculate the area of different domains, which are labeled by a connected component, the focus distance can be found via the smallest area of each CD. Meanwhile, the sectional images without defocus noise can also be reconstructed based on the labeled domains. The effectiveness of this method has been verified with a simulation and experiments.

10.
Int J Genomics ; 2018: 2456076, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29693000

RESUMO

miRNAs are a class of noncoding RNAs important in posttranscriptional repressors and involved in the regulation of almost every biological process by base paring with target genes through sequence in their seed regions. Genetic variations in the seed regions have vital effects on gene expression, phenotypic variation, and disease susceptibility in humans. The distribution pattern of genetic variation in miRNA seed regions might be related to miRNA function and is worth paying more attention to. We here employed computational analyses to explore the clustering pattern and functional effect of SNPs in human miRNA seed regions. A total of 1879 SNPs were mapped to 1226 human miRNA seed regions. We found that miRNAs with SNPs in their seed region are significantly enriched in miRNA clusters. We also found that SNPs in clustered miRNA seed regions have a lower functional effect than have SNPs in nonclustered miRNA seed regions. Additionally, we found that clustered miRNAs with SNPs in seed regions are involved in more pathways. Overall, our results demonstrate that SNPs in clustered miRNA seed regions can take part in more intricate and complex gene-regulating networks with lower functional cost by functional complementarity. Moreover, our results also broaden current knowledge on the genetic variation in human miRNA seed regions.

11.
Schizophr Res ; 199: 176-180, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29499969

RESUMO

Genome-wide association studies (GWAS) reveal numerous schizophrenia (SCZ)-associated single-nucleotide polymorphisms (SNPs); however, functional characterizations of the risk variants remain to be established. Using data from 108 SCZ GWAS loci, we performed systematic miRNA binding site screening of 128 SCZ-associated SNPs and found that 2 out of 3 SNPs located in the 3'UTR were predicted to alter 3 miRNAs' binding sites in 2 target genes. Of the identified SNPs, the most genome-wide significant SNP rs4702 (A/G) in the FURIN 3'UTR, previously identified as an SCZ-associated cis-expression quantitative trait loci (downregulated by the risk G allele), is located in the binding site of miR-338-3p in the presence of the risk G allele. Allele-specific downregulation of FURIN by miR-338-3p was validated with a luciferase reporter assay. Furthermore, we demonstrated that miR-338-3p-mediated FURIN inhibition reduced brain-derived neurotrophic factor (BDNF) maturation and secretion in human embryonic kidney 293T cells. Our data reveal that schizophrenia-associated rs4702 G allele-specific downregulation of FURIN by miR-338-3p reduces mature BDNF production. These data help elucidate the mechanism of genetic predisposition toward schizophrenia or other neurodevelopmental diseases.


Assuntos
Fator Neurotrófico Derivado do Encéfalo/metabolismo , Furina/genética , Furina/metabolismo , MicroRNAs/metabolismo , Esquizofrenia/genética , Esquizofrenia/metabolismo , Biologia Computacional , Regulação para Baixo , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Células HEK293 , Humanos , Polimorfismo de Nucleotídeo Único
12.
Opt Express ; 26(4): 3756-3771, 2018 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-29475355

RESUMO

This paper presents a method to identify the axial location of targets in an optical scanning holography (OSH) system. By combining time reversal (TR) technique with the multiple signal classification (MUSIC) method in OSH, axial location can be detected with high resolution. Both simulation and experimental work have been carried out to verify the feasibility of the proposed work.

13.
Opt Lett ; 42(18): 3670-3673, 2017 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-28914929

RESUMO

We derive from Maxwell's equations full-vectorial nonlinear propagation equations of four-wave mixing valid in straight semiconductor-on-insulator waveguides. Special attention is given to the resulting effective mode area, which takes a convenient form known from studies in photonic crystal fibers, but has not been introduced in the context of integrated waveguides. We show that the difference between our full-vectorial effective mode area and the scalar equivalent often referred to in the literature may lead to mistakes when evaluating the nonlinear refractive index and optimizing designs of new waveguides. We verify the results of our derivation by comparing it to experimental measurements in a silicon-on-insulator waveguide, taking tolerances on fabrication parameters into account.

14.
Sci Rep ; 7(1): 9798, 2017 08 29.
Artigo em Inglês | MEDLINE | ID: mdl-28852169

RESUMO

ABSTARCT: We report for the first time a NUV light to white light conversion in a N-B co-doped 6H-SiC (fluorescent SiC) layer containing a hybrid structure. The surface of fluorescent SiC sample contains porous structures fabricated by anodic oxidation method. After passivation by 20 nm thick Al2O3, the photoluminescence intensity from the porous layer was significant enhanced by a factor of more than 12. Using a porous layer of moderate thickness (~10 µm), high-quality white light emission was realized by combining the independent emissions of blue-green emission from the porous layer and yellow emission from the bulk fluorescent SiC layer. A high color rendering index of 81.1 has been achieved. Photoluminescence spectra in porous layers fabricated in both commercial n-type and lab grown N-B co-doped 6H-SiC show two emission peaks centered approximately at 460 nm and 530 nm. Such blue-green emission phenomenon can be attributed to neutral oxygen vacancies and interface C-related surface defects generated dring anodic oxidation process. Porous fluorescent SiC can offer a great flexibility in color rendering by changing the thickness of porous layer and bulk fluorescent layer. Such a novel approach opens a new perspective for the development of high performance and rare-earth element free white light emitting materials.

15.
Nanoscale ; 8(36): 16340-16348, 2016 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-27714107

RESUMO

Surface plasmon coupling with light-emitters and surface nano-patterning have widely been used separately to improve low efficiency InGaN light-emitting diodes. We demonstrate a method where dielectric nano-patterning and Ag nanoparticles (NPs) are combined to provide both light extraction and internal quantum efficiency enhancement for InGaN/GaN quantum-well light-emitters. By fabricating dielectric nano-rod pattern on the GaN surface, an optical coating that improves the light extraction is obtained, and furthermore has a low refractive index which blue-shifts the plasmonic resonance of Ag NPs towards the emission wavelength. We investigate emission components from both the GaN and sapphire surface of the semiconductor crystal and show that Ag NPs on dielectric nano-pattern compared to a planar surface, result in a stronger enhancement.

16.
Micromachines (Basel) ; 7(9)2016 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-30404323

RESUMO

An approach for fabricating sub-wavelength antireflective structures on SiC material is demonstrated. A time-efficient scalable nanopatterning method by rapid thermal annealing of thin metal film is applied followed by a dry etching process. Size-dependent optical properties of the antireflective SiC structures have been investigated. It is found that the surface reflection of SiC in the visible spectral range is significantly suppressed by applying the antireflective structures. Meanwhile, optical transmission and absorption could be tuned by modifying the feature size of the structure. It is believed that this effective fabrication method of antireflective structures could also be realized on other semiconductor materials or devices.

17.
Opt Lett ; 40(17): 4146-9, 2015 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-26368733

RESUMO

Random phase masks can transform the defocus noise into a speckle-like pattern in optical scanning holography (OSH). In this Letter, we presented a speckle reduction based on combined frame difference and connected component method in a random phase-coded OSH system. The image quality of the reconstructed sections is improved with better visibility.

18.
Opt Express ; 23(3): 3292-8, 2015 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-25836187

RESUMO

We report the design and fabrication of a compact multi-core fiber fan-in/fan-out using a grating coupler array on the SOI platform. The grating couplers are fully-etched, enabling the whole circuit to be fabricated in a single lithography and etching step. Thanks to the apodized design for the grating couplers and the introduction of an aluminum reflective mirror, a highest coupling efficiency of -3.8 dB with 3 dB coupling bandwidth of 48 nm and 1.5 dB bandwidth covering the whole C band, together with crosstalk lower than -32 dB are demonstrated.

19.
Sci Rep ; 4: 6392, 2014 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-25242090

RESUMO

Surface plasmonics from metal nanoparticles have been demonstrated as an effective way of improving the performance of low-efficiency light emitters. However, reducing the inherent losses of the metal nanoparticles remains a challenge. Here we study the enhancement properties by Ag nanoparticles for InGaN/GaN quantum-well structures. By using a thin SiN dielectric layer between Ag and GaN we manage to modify and improve surface plasmon coupling effects, and we attribute this to the improved scattering of the nanoparticles at the quantum-well emission wavelength. The results are interpreted using numerical simulations, where absorption and scattering cross-sections are studied for different sized particles on GaN and GaN/SiN substrates.

20.
Opt Express ; 22(10): 12467-74, 2014 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-24921364

RESUMO

Polarization insensitive wavelength conversion of a 40 Gb/s non-return-to-zero (NRZ) differential phase-shift keying (DPSK) data signal is demonstrated using four-wave mixing (FWM) in a silicon nanowire circuit. Polarization independence is achieved using a diversity circuit based on polarization rotators and splitters, which is fabricated by a simple process on the silicon-on-insulator (SOI) platform. Error-free performance is achieved with only 0.5 dB of power penalty compared to the wavelength conversion of a signal with well optimized input polarization. Additionally, data transmission over 161 km standard single-mode fiber (SSMF) is demonstrated at 40 Gb/s using optical phase conjugation (OPC) in the proposed circuit.

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