474 research outputs found

    Graphene Transistor Based Nanoelectronic and Nanophotonic Applications.

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    Over the past few decades, electronics and photonics have made significant impacts on every aspect of our daily life. Importantly, as the technology advancing and moving forward, the development of these devices not only relies on deeper fundamental understanding but also requires novel materials with unique properties as well as new device architecture to achieve higher performance with more diverse functionalities. In this regards, low dimensional materials inherently possess properties that are conceptually different from those of bulk materials in most aspects. The capability to tailor these nanomaterials as well as their unique properties is essential to achieve unconventional devices with revolutionary impacts. In this dissertation work, our aim is to develop novel nanoelectronics and nanophotonics by exploiting the extraordinary characteristics of purely two-dimensional (2D) monolayer graphene and its heterostructures. Firstly, we design and propose the dual-gate graphene ambipolar transistor that can operate as either common mode or differential mode amplifier by properly tuning the gate biases. Our device can also achieve high noise rejection amplification with common mode rejection ration (CMRR) as high as 80 dB, which is comparable to a commercial operational amplifier (op-amp). Secondly, we demonstrate the hyperbolic metamaterials (HMMs) by using precisely controlled periodic graphene-dielectric multilayer nanostructures to investigate the optical topological transition from elliptical to hyperbolic dispersion in mid-infrared regime. Thirdly, we propose the graphene-SOI heterojunction broadband photodetector design to improve the device on-off operation speed, strengthen the photo-gating effect, as well as minimize the dark current. We further fabricate the single pixels into 32 x 32 matrix arrangement to demonstrate the proof-of-concept image array readout, opening up the development of graphene-based ultra-broadband image sensor array applications. Lastly, we propose the all-graphene transparent photodetector design for light-field imaging and demonstrate the proof-of-concept one-dimensional (1D) ranging by using two stacked single-pixel transparent photodetectors. The results should lay the stepping stones and foundation for the new generation of graphene-based light-field photodetectors and image sensors.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/135842/1/chehung_1.pd

    NCNet: Deep Learning Network Models for Predicting Function of Non-coding DNA

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    The human genome consists of 98.5% non-coding DNA sequences, and most of them have no known function. However, a majority of disease-associated variants lie in these regions. Therefore, it is critical to predict the function of non-coding DNA. Hence, we propose the NCNet, which integrates deep residual learning and sequence-to-sequence learning networks, to predict the transcription factor (TF) binding sites, which can then be used to predict non-coding functions. In NCNet, deep residual learning networks are used to enhance the identification rate of regulatory patterns of motifs, so that the sequence-to-sequence learning network may make the most out of the sequential dependency between the patterns. With the identity shortcut technique and deep architectures of the networks, NCNet achieves significant improvement compared to the original hybrid model in identifying regulatory markers

    Percutaneous Transhepatic Cholangiography and Drainage is an Effective Rescue Therapy for Biliary Complications in Liver Transplant Recipients Who Fail Endoscopic Retrograde Cholangiopancreatography

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    BackgroundWe attempted to evaluate both the factors that predispose a patient to biliary complications after liver transplantation and the results of percutaneous transhepatic cholangiography and drainage (PTCD) for the management of those complications.MethodsThis study retrospectively reviewed the cases of 81 patients who received liver transplants at Taipei Veterans General Hospital between February 2003 and June 2008. Biliary complications were diagnosed on the basis of clinical findings, laboratory data, and the results of imaging studies.ResultsA total of 18 patients (22.2%) developed biliary complications, and living donor liver transplantation (LDLT) was a significant risk factor (p = 0.035), compared to cadaveric liver transplantation. Eight patients with biliary complications received PTCD as the first treatment modality and 6 had successful results. An additional 10 patients received endoscopic retrograde cholangiopancreatography (ERCP) initially, but only 2 patients were effectively managed. One patient received conservative treatment after ERCP failure. One patient died from sepsis after ERCP. The remaining 6 patients with failed ERCP were successfully managed with PTCD. The overall mortality rate in these patients with biliary complications was 16.7%. No significant prognostic predictors were identified, including age, sex, biochemical data, and model for end-stage liver disease scores.ConclusionBiochemical markers cannot predict biliary complications preoperatively. LDLT increases the risk of biliary complications. PTCD is an effective rescue therapy when ERCP fails

    An Extract of Antrodia camphorata Mycelia Attenuates the Progression of Nephritis in Systemic Lupus Erythematosus-Prone NZB/W F1 Mice

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    Antrodia camphorata is used in folk medicine for the treatment of inflammation syndromes and liver-related diseases in Taiwan. The goal of this study was to evaluate the efficacy of the mycelial extract of A. camphorata (ACE) for the treatment of systemic lupus erythematosus (SLE) in SLE-prone NZB/W F1 mice. After antibodies against double-stranded DNA appeared in NZB/W mice, the mice were orally administered varying dosages of ACE (100, 200 and 400 mg kg−1) for 5 consecutive days per week for 12 weeks via gavage. To assess the efficacy of ACE, we measured SLE-associated biochemical and histopathological biomarkers levels of blood urine nitrogen (BUN), blood creatinine, urine protein and urine creatinine and thickness of the kidney glomerular basement membrane by staining with periodic acid-Schiff. Antroquinonol, an active component of ACE, was investigated for anti-inflammation activity in lipopolysaccharide-induced RAW 267.4 cells. ACE at 400 mg kg−1 significantly suppressed urine protein and serum BUN levels and decreased the thickness of the kidney glomerular basement membrane. Antroquinonol significantly inhibited the production of tumor necrosis factor-α and interleukin-1β by 75 and 78%, respectively. In conclusion, ACE reduced urine protein and creatinine levels and suppressed the thickening of the kidney glomerular basement membrane, suggesting that ACE protects the kidney from immunological damage resulting from autoimmune disease

    Role of SIRT3 in the regulation of redox balance during oral carcinogenesis

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    Роль органів державної влади та місцевого самоврядування в процесі реалізації прав людини і громадянина на одержання інформації

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    Автор досліджує роль органів державної влади та місцевого самоврядування в процесі реалізації прав людини і громадянина на одержання інформації При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/36646Автор исследует роль органов государственной власти и местного самоуправления в процессе реализации прав человека и гражданина на получение информации При цитировании документа, используйте ссылку http://essuir.sumdu.edu.ua/handle/123456789/36646The author explores the role of state and local authorities in the implementation of human and civil rights to information When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3664

    Cytochrome P450 Metabolism of Betel Quid-Derived Compounds: Implications for the Development of Prevention Strategies for Oral and Pharyngeal Cancers

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    Betel quid (BQ) products, with or without tobacco, have been classified by the International Agency for Research on Cancer (IARC) as group I human carcinogens that are associated with an elevated risk of oral potentially malignant disorders (OPMDs) and cancers of the oral cavity and pharynx. There are estimated 600 million BQ users worldwide. In Taiwan alone there are 2 million habitual users (approximately 10% of the population). Oral and pharyngeal cancers result from interactions between genes and environmental factors (BQ exposure). Cytochrome p450 (CYP) families are implicated in the metabolic activation of BQ- and areca nut-specific nitrosamines. In this review, we summarize the current knowledge base regarding CYP genetic variants and related oral disorders. In clinical applications, we focus on cancers of the oral cavity and pharynx and OPMDs associated with CYP gene polymorphisms, including CYP1A1, CYP2A6, CYP2E1, and CYP26B1. Our discussion of CYP polymorphisms provides insight into the importance of screening tests in OPMDs patients for the prevention of oral and pharyngeal cancers. Future studies will establish a strong foundation for the development of chemoprevention strategies, polymorphism-based clinical diagnostic tools (e.g., specific single-nucleotide polymorphism (SNP) “barcodes”), and effective treatments for BQ-related oral disorders

    Antrodia camphorata Mycelia Attenuates the Progression of Nephritis in Systemic Lupus Erythematosus-Prone NZB/W F1 Mice

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    Antrodia camphorata is used in folk medicine for the treatment of inflammation syndromes and liver-related diseases in Taiwan. The goal of this study was to evaluate the efficacy of the mycelial extract of A. camphorata (ACE) for the treatment of systemic lupus erythematosus (SLE) in SLE-prone NZB/W F1 mice. After antibodies against double-stranded DNA appeared in NZB/W mice, the mice were orally administered varying dosages of ACE (100, 200 and 400 mg kg −1 ) for 5 consecutive days per week for 12 weeks via gavage. To assess the efficacy of ACE, we measured SLE-associated biochemical and histopathological biomarkers levels of blood urine nitrogen (BUN), blood creatinine, urine protein and urine creatinine and thickness of the kidney glomerular basement membrane by staining with periodic acid-Schiff. Antroquinonol, an active component of ACE, was investigated for antiinflammation activity in lipopolysaccharide-induced RAW 267.4 cells. ACE at 400 mg kg −1 significantly suppressed urine protein and serum BUN levels and decreased the thickness of the kidney glomerular basement membrane. Antroquinonol significantly inhibited the production of tumor necrosis factor-α and interleukin-1β by 75 and 78%, respectively. In conclusion, ACE reduced urine protein and creatinine levels and suppressed the thickening of the kidney glomerular basement membrane, suggesting that ACE protects the kidney from immunological damage resulting from autoimmune disease

    ATF3 Sustains IL-22-Induced STAT3 Phosphorylation to Maintain Mucosal Immunity Through Inhibiting Phosphatases

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    In gut epithelium, IL-22 transmits signals through STAT3 phosphorylation (pSTAT3) which provides intestinal immunity. Many components in the IL-22-pSTAT3 pathway have been identified as risk factors for inflammatory bowel disease (IBD) and some of them are considered as promising therapeutic targets. However, new perspectives are still needed to understand IL-22-pSTAT3 signaling for effective clinical interventions in IBD patients. Here, we revealed activating transcription factor 3 (ATF3), recently identified to be upregulated in patients with active IBD, as a crucial player in the epithelial IL-22-pSTAT3 signaling cascade. We found ATF3 is central to intestinal homeostasis and provides protection during colitis. Loss of ATF3 led to decreased crypt numbers, more shortened colon length, impaired ileal fucosylation at the steady state, and lethal disease activity during DSS-induced colitis which can be effectively ameliorated by rectal transplantation of wild-type colonic organoids. Epithelial stem cells and Paneth cells form a niche to orchestrate epithelial regeneration and host-microbe interactions, and IL-22-pSTAT3 signaling is a key guardian for this niche. We found ATF3 is critical for niche maintenance as ATF3 deficiency caused compromised stem cell growth and regeneration, as well as Paneth cell degeneration and loss of anti-microbial peptide (AMP)-producing granules, indicative of malfunction of Paneth/stem cell network. Mechanistically, we found IL-22 upregulates ATF3, which is required to relay IL-22 signaling leading to STAT3 phosphorylation and subsequent AMP induction. Intriguingly, ATF3 itself does not act on STAT3 directly, instead ATF3 regulates pSTAT3 by negatively targeting protein tyrosine phosphatases (PTPs) including SHP2 and PTP-Meg2. Furthermore, we identified ATF3 is also involved in IL-6-mediated STAT3 activation in T cells and loss of ATF3 leads to reduced capacity of Th17 cells to produce their signature cytokine IL-22 and IL-17A. Collectively, our results suggest that via IL-22-pSTAT3 signaling in the epithelium and IL-6-pSTAT3 signaling in Th17 cells, ATF3 mediates a cross-regulation in the barrier to maintain mucosal homeostasis and immunity
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