Browsing by Issue Date, starting with "2020-04-07"

Now showing 1 - 20 of 5258

Linker and N-Terminal Domain Engineering of Pyrrolysyl-tRNA Synthetase for Substrate Range Shifting and Activity Enhancement
(2020-04-07)
Jiang, Han-Kai
;
Lee, Man-Nee
;
Tsou, Jo-Chu
;
Chang, Kuan-Wen
;
Tseng, Hsueh-Wei
The Methanosarcina mazei pyrrolysyl-tRNA synthetase (PylRS).tRNA(Pyl) pair can be used to incorporate non-canonical amino acids (ncAAs) into proteins at installed amber stop codons. Although engineering of the PylRS active site generates diverse binding pockets, the substrate ranges are found similar in charging lysine and phenylalanine analogs. To expand the diversity of the ncAA side chains that can be incorporated via the PylRS.tRNA(Pyl) pair, exploring remote interactions beyond the active site is an emerging approach in expanding the genetic code research. In this work, remote interactions between tRNA(Pyl), the tRNA binding domain of PylRS, and/or an introduced non-structured linker between the N- and C-terminus of PylRS were studied. The substrate range of the PylRS.tRNA(Pyl) pair was visualized by producing sfGFP-UAG gene products, which also indicated amber suppression efficiencies and substrate specificity. The unstructured loop linking the N-terminal and C-terminal domains (CTDs) of PylRS has been suggested to regulate the interaction between PylRS and tRNA(Pyl). In exploring the detailed role of the loop region, different lengths of the linker were inserted into the junction between the N-terminal and the C-terminal domains of PylRS to unearth the impact on remote effects. Our findings suggest that the insertion of a moderate-length linker tunes the interface between PylRS and tRNA(Pyl) and subsequently leads to improved suppression efficiencies. The suppression activity and the substrate specificity of PylRS were altered by introducing three mutations at or near the N-terminal domain of PylRS (N-PylRS). Using a N-PylRS.tRNA(Pyl) pair, three ncAA substrates, two S-benzyl cysteine and a histidine analog, were incorporated into the protein site specifically.
Solution-processed organometallic quasi-two-dimensional nanosheets as a hole buffer layer for organic light-emitting devices
(2020-04-07)
Liu, Shihao
;
Wang, Ying-Chiao
;
Chang, Chi-Ming
;
Yasuda, Takeshi
;
Fukui, Naoya
Two-dimensional (2D) vdW materials have been integrated into optoelectronic devices to achieve exceptional functionality. However, the integration of large-area 2D thin films into organic light-emitting devices (OLEDs) remains challenging because of the finite number of inorganic 2D materials and the high-temperature requirements of their deposition process. The construction of 2D organometallic materials holds immense potential because of their solution synthesis and unlimited structural and functional diversity. Here, we report a facile route using an oil-water interfacial coordination reaction between organic ligands and divalent metal ions to synthesize crystalline quasi-2D organometallic bis(dithiolato)nickel (NiDT) nanosheets with a centimeter scale and a tunable thickness. The NiDT nanosheets can be directly integrated into OLEDs for use as a hole buffer layer and a fluorescent mounting medium without the aid of a transfer process. Moreover, OLEDs with NiDT nanosheets show not only comparable efficiency to conventional OLEDs but also prolonged device lifetime by nearly 2 times. These results open up a new dimension to use quasi-2D organometallic nanosheets as functional layers in large-area organic devices.
Face-on reorientation of pi-conjugated polymers in thin films by surface-segregated monolayers
(2020-04-07)
Wang, Wei-Chih
;
Chen, Sheng-Yuan
;
Yang, Yaw-Wen
;
Hsu, Chain-Shu
;
Tajima, Keisuke
A new pi-conjugated polymer based on naphthalenediimide with a branched semifluoroalkyl side chain (FNDIT2) was synthesized and used to change the polymer orientations in thin films. X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy revealed that FNDIT2 spontaneously forms surface-segregated monolayers in blend films with other pi-conjugated polymers to adopt a preferred face-on orientation, with the pi-plane of the polymer aligned more parallel to the surface. Thermal annealing of the films induced further reorientation of the polymers inside the films closer to the face-on orientation, as shown by two-dimensional grazing-incidence wide-angle X-ray scattering. The induced face-on orientations in the films led to higher charge mobility in the vertical direction. This study provides a general and versatile strategy to control the molecular orientation in thin films and enhance the performance of thin-film organic electronics.
Cognitive Reserve Moderates Effects of White Matter Hyperintensity on Depressive Symptoms and Cognitive Function in Late-Life Depression
(2020-04-08)
Lin, Chemin
;
Huang, Chih-Mao
;
Fan, Yang-Teng
;
Liu, Ho-Ling
;
Chen, Yao-Liang
Introduction White matter hyperintensity (WMH) has been regarded as one of the major contributor of the vascular hypothesis of late-life depression (LLD) and cognitive decline in the elderly. On the other hand, cognitive reserve (CR) has long been hypothesized to provide resilience and adaptability against age- and disease-related insults. This study examined the role of CR, using proxy of education, in moderating the association between WMH and clinical LLD expression. Methods A total of 54 elderly diagnosed with major depressive disorder and 38 matched healthy controls participated in this study. They received MRI scanning and a battery of neuropsychological tests. WMH was quantified by an automated segmentation algorithm. Linear regression analyses were conducted separately in the LLD and control groups to examine the effects of WMH, education and their interaction in depression severity and various cognitive domains. Results WMH was significantly and negatively associated with executive function only in the healthy controls. In patients with LLD, we observed a significant interactive effect in education on the association between WMH and depression severity and language domain (category fluency task). Specifically, those with high education showed less depressive symptoms and cognitive decline as WMH increased. Conclusion WMH is associated with lower cognitive function. However, in patients with LLD, high education attenuates the deleterious effect of WMH on mood and cognition. Therefore, CR appears to exert a protective effect on neurocognitive functioning in people with LLD.
Chiral Second-Harmonic Generation from Monolayer WS2/Aluminum Plasmonic Vortex Metalens
(2020-04-08)
Guo, Wan-Ping
;
Liang, Wei-Yun
;
Cheng, Chang-Wei
;
Wu, Wei-Lin
;
Wang, Yen-Ting
Two-dimensional spiral plasmonic structures have emerged as a versatile approach to generate near-field vortex fields with tunable topological charges. We demonstrate here a far-field approach to observe the chiral second-harmonic generation (SHG) at designated visible wavelengths from a single plasmonic vortex metalens. This metalens comprises an Archimedean spiral slit fabricated on atomically flat aluminum epitaxial film, which allows for precise tuning of plasmonic resonances and subsequent transfer of two-dimensional materials on top of the spiral slit. The nonlinear optical measurements show a giant SHG circular dichroism. Furthermore, we have achieved an enhanced chiral SHG conversion efficiency (about an order of magnitude greater than the bare aluminum lens) from monolayer tungsten disulfide (WS2)/aluminum metalens, which is designed at the C-exciton resonance of WS2. Since the C-exciton is not a valley exciton, the enhanced chiral SHG in this hybrid system originates from the plasmonic vortex field-enhanced SHG under the optical spin-orbit interaction.
Lipoplex-based targeted gene therapy for the suppression of tumours with VEGFR expression by producing anti-angiogenic molecules
(2020-04-09)
Ho, Shu-Yi
;
Chen, Pin-Rong
;
Chen, Chia-Hung
;
Tsai, Nu-Man
;
Lin, Yu-Hsin
Background The anti-angiogenic fusion protein RBDV-IgG1 Fc (RBDV), which comprises the receptor-binding domain of vascular endothelial growth factor-A (VEGF-A), has shown antitumour effects by reducing angiogenesis in vivo. This study used the cationic lipoplex lipo-PEG-PEI-complex (LPPC) to simultaneously encapsulate both the RBDV targeting protein and the RBDV plasmid (pRBDV) without covalent bonds to assess VEGFR targeting gene therapy in mice with melanoma in vivo. Results LPPC protected the therapeutic transgene from degradation by DNase, and the LPPC/RBDV complexes could specifically target VEGFR-positive B16-F10 cells both in vitro and in vivo. With or without RBDV protein-targeting direction, the pRBDV-expressing RBDV proteins were expressed and reached a maximal concentration on the 7th day in the sera after transfection in vivo and significantly elicited growth suppression against B16-F10 melanoma but not IgG1 control proteins. In particular, LPPC/pRBDV/RBDV treatment with the targeting molecules dramatically inhibited B16-F10 tumour growth in vivo to provide better therapeutic efficacy than the treatments with gene therapy with IgG1 protein targeting or administration of a protein drug with RBDV. Conclusions The simultaneous combination of the LPPC complex with pRBDV gene therapy and RBDV protein targeting might be a potential tool to conveniently administer targeted gene therapy for cancer therapy.
Neutral oxygen irradiation enhanced forming-less ZnO-based transparent analog memristor devices for neuromorphic computing applications
(2020-04-09)
Simanjuntak, Firman Mangasa
;
Ohno, Takeo
;
Chandrasekaran, Sridhar
;
Tseng, Tseung-Yuen
;
Samukawa, Seiji
Surface oxidation employing neutral oxygen irradiation significantly improves the switching and synaptic performance of ZnO-based transparent memristor devices. The endurance of the as-irradiated device is increased by 100 times, and the operating current can be lowered by 10 times as compared with the as-deposited device. Moreover, the performance-enhanced device has an excellent analog behavior that can exhibit 3 bits per cell nonvolatile multistate characteristics and perform 15 stable epochs of synaptic operations with highly linear weight updates. A simulated artificial neural network comprising 1600 synapses confirms the superiority of the enhanced device in processing a 40 x 40 pixels grayscale image. The irradiation effectively decreases the concentration of oxygen vacancy donor defects and promotes oxygen interstitial acceptor defects on the surface of the ZnO films, which consequently modulate the redox process during rupture and rejuvenation of the filament. This work not only proposes the potential of ZnO-based memristor devices for high-density invisible data storage and in-memory computing application but also offers valuable insight in designing high-performance memristor devices, regardless of the oxide system used, by taking advantage of our neutral oxygen irradiation technique.
Impact of Cumulative Unhealthy Sleep Practices in Adolescence on Substance Use in Young Adulthood Estimated Using Marginal Structural Modeling
(2020-04-09)
Ho, Chia-Yi
;
Lin, Sheng-Hsuan
;
Tsai, Meng-Che
;
Yu, Tsung
;
Strong, Carol
Objectives The purpose of this study was to identify the impact of chronic, unhealthy sleep practices in adolescence on substance use in young adulthood. Unhealthy sleep practices in adolescent samples exhibit a bidirectional relationship with substance use. The relationship is further complicated if we consider that confounders such as depression vary over time and are often in response to adolescents' prior poor sleep practice, which can be addressed by a counterfactual approach using a marginal structural model. Methods Data in this study are from the Taiwan Youth Project, a longitudinal study that started in 2000 and surveyed 2,690 7th grade students at age 13. Outcomes include frequency of cigarette smoking and alcohol drinking at age 21. Three unhealthy sleep practices were included in this study: short sleep, social jetlag, and sleep disturbance. We used a marginal structural model with stabilized inverse probability-of-treatment weights to address time-varying confounders in each wave and a total sample of 1,678 adolescents with complete information for this study. Results Accumulated waves of sleep disturbance and social jetlag in adolescence were significantly associated with cigarette use in young adulthood. Accumulated social jetlag but not sleep disturbance was also associated with alcohol use in adulthood. Accumulated waves of short sleep were not associated with later alcohol use, but were negatively correlated with cigarette use. Conclusion Interventions that aim to reduce the likelihood of substance use in young adulthood should consider confronting unhealthy sleep practices, in particular the discrepancy between bedtimes on school days and weekends and sleep disturbance.
Adjustable panoramic inspection system for submillimeter fasteners
(2020-04-10)
Yan, Yung-Jhe
;
Tsai, Ming-Shiou
;
Chen, Wen-Bin
;
Chen, You-Bo
;
Sun, Ching-Cherng
Fasteners are critical and indispensable locking components in mechanical assembly. Submillimeter fasteners are massively and widely used in electronic devices. This study proposed an adjustable panoramic inspection system for M2 to M0.8 submillimeter fasteners. The system mainly consists of a panoramic imaging module, a back-light module, and an image grabbing and computing module. The panoramic imaging module would form four equal optical path lengths to keep the same imaging amplification between the different directions of the field of view. The back-light module was designed to provide uniform illumination and enhance the contrast of the pitch edge between the fasteners and the background. The image grabbing and computing module with a high-speed camera was designed to be adjustable for different sizes of submillimeter fasteners. The realized system can offer the function of four images in one shot to make a panoramic scene, independent illumination for recognizing, inspect screws from M0.8 to M2.0 screws, and short time consumption of image processing, such as 3.284 ms for M0.8 screws and 2.384 ms for M2.0 screws, to achieve examination of 6000 pieces in 1 min. (C) 2020 Optical Society of America.
Rotational spectroscopy and astronomical search for glutaronitrile
(2020-04-10)
Cabezas, C.
;
Bermudez, C.
;
Endo, Y.
;
Tercero, B.
;
Cernicharo, J.
Context. Nitriles constitute almost 15% of the molecules observed in the interstellar medium (ISM), surprisingly only two dinitriles have been detected in the ISM so far. The lack of astronomical detections for dinitriles may be partly explained by the absence of laboratory rotational spectroscopic data.Aims. Our goal is to investigate the rotational spectrum of glutaronitrile, N equivalent to C-CH2-CH2-CH2-C equivalent to N, in order to allow its possible detection in the ISM.Methods. The rotational spectrum of glutaronitrile was measured using two different experimental setups. A Fourier transform microwave spectrometer was employed to observe the supersonic jet rotational spectrum of glutaronitrile between 6 and 20 GHz. In addition, the mmW spectrum was observed in the frequency range 72-116.5 GHz using a broadband millimetre-wave spectrometer based on radio astronomy receivers with fast Fourier transform backends. The spectral searches were supported by high-level ab initio calculations.Results. A total of 111 rotational transitions with maximum values of J and K-a quantum numbers 54 and 18, respectively, were measured for the gg conformer of glutaronitrile. The analysis allowed us to accurately determine the rotational, nuclear quadrupole coupling, quartic and sextic centrifugal distortion constants. These rotational parameters were employed to search for glutaronitrile in the cold and warm molecular clouds Orion KL, Sgr B2(N), B1-b and TMC-1, using the spectral surveys captured by IRAM 30 m at 3 mm. Glutaronitrile was not detected, and the upper limits' column densities were derived. Those are a factor of 1.5 and 5 lower than those obtained for the total column densities of the analogous succinonitrile in Orion KL and Sgr B2, respectively.
連假趴趴走　惹議也惹「疫」
(2020-04-12)
張筠婕
;
Department of Communication and Technology
;
傳播與科技學系
新型冠狀病毒（COVID-19）在全球蔓延，根據中央流行疫情指揮中心統計，國內截至目前有385人確診（境外移入331例、本土感染54例）、6人死亡。相較許多疫情爆發的國家，台灣的防疫受到各國的讚賞及效仿，成為全球熱議焦點。不過，在經過四天的清明連假，不少人擔心台灣各景點的人潮已成為防疫破口，引發許多爭議。
想像與恐懼　怪物對你的心理戰
(2020-04-12)
邱于非
;
Department of Communication and Technology
;
傳播與科技學系
兒童文學中的怪物其實是有演變規則的，面對不同年齡層擁有的想像力與心態成熟度，如何會是「成功的」怪物，其中需要依循的是許多層面的心理學。
「圓」來沒自信　但要很努力
(2020-04-12)
詹庭瑄
;
Department of Communication and Technology
;
傳播與科技學系
她，沒有浪費任何舞台下的日常累積，那些在咖啡廳自我懷疑、在電視台焦頭爛額、在韓國冒險的日子，成為了最好的養分，造就如今54萬訂閱的Youtuber。她是阿圓，本名王莉茵，一個沒有自信，但很努力的女孩。
芝麻開門　走進平等的藝術世界
(2020-04-12)
何雨潮
;
Department of Communication and Technology
;
傳播與科技學系
林滿足自稱「小小米」，也就是芝麻開門（Sesame）的音譯。她希望能成為人與藝術之間的橋梁，帶領人們走入藝術大門。
用玩具紀錄人生的大男孩
(2020-04-12)
李詠濠
;
Department of Communication and Technology
;
傳播與科技學系
紀錄回憶有千種方法，你有沒有想過用玩具記下自己曾經發生過的事？
李榮峰　尊重生命的行動教育家
(2020-04-12)
梁子敬
;
Department of Communication and Technology
;
傳播與科技學系
「要先懂得尊重動物，才有辦法去愛人，我要用教育改變這個世界。」
「憾」你再次活著，第二個人生
(2020-04-12)
黃博暄
;
Department of Communication and Technology
;
傳播與科技學系
如果某一天妳死而復生，你最想做的是什麼？韓國熱播連續劇《哈囉掰掰，我是鬼媽媽》，透過深刻描寫鬼媽媽死後和復生的心境，來探討死亡的議題。
大自然的女兒　張碧員
(2020-04-12)
李而
;
Department of Communication and Technology
;
傳播與科技學系
一本書是如何誕生的？大樹文化主編張碧員從她熱愛的大自然裡獲取創作養分，真實地記錄她眼中的一草一木。對她來說，大自然不僅僅是工作的場域，更是養育她，使她不斷成長的溫暖母親。
Kumu Walis　台灣與大溪地間的橋樑
(2020-04-12)
王冠云
;
Department of Communication and Technology
;
傳播與科技學系
賽德克原住民與大溪地，透過舞蹈連結了南島民族，建立文化之間的交流。
那些年，我們誤會的「八卦」
(2020-04-12)
廖玥茹
;
Department of Communication and Technology
;
傳播與科技學系
你有沒有想過，為什麼多數人不願自己被貼上「愛說八卦」的標籤，但還是喜歡談論他人的事？一個德國研究在調查人們八卦的動機時，也分析了「黑暗」的人是否更容易跟別人咬耳根子。然而種種結果都與我們認知不同，八卦的壞名聲似乎看起來不太合理。