Browsing by Issue Date, starting with "2020-01-21"

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A chlorinated nonacyclic carbazole-based acceptor affords over 15% efficiency in organic solar cells
(2020-01-21)
Chen, Tsung-Wei
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Peng, Kuan-Lin
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Lin, You-Wei
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Su, Yi-Jia
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Ma, Ko-Jui
In this contribution, a dithienocyclopentacarbazole (DTC)-based and two dithieno[3,2-b]thiophenecyclopentacarbazole (DTTC)-based non-fullerene acceptors (NFAs) named DTC-4F, DTTC-4F and DTTC-4Cl were exploited to elucidate the effects of conjugation extension and end group chlorination. DTTC-4F was designed through conjugation extension on the basis of DTC-4F by fusing one additional thiophene on both flanks of the heptacyclic DTC core, generating the nonacyclic DTTC core. Compared with DTC-4F, DTTC-4F features up-shifted energy levels, red-shifted absorption and enhanced pi-pi interaction. PM6:DTTC-4F exhibits a decent PCE of 13.89% with a V-OC of 0.95 V, a J(SC) of 21.66 mA cm(-2) and a FF of 67.60%. Although DTTC-4F affords a reduced FF compared to DTC-4F, a DTTC-4F-based device delivers a higher PCE than DTC-4F-based devices due to the extended absorption range of DTCC-4F in comparison with DTC-4F. Since chlorinated NFAs are known to possess stronger pi-pi interaction than fluorinated NFAs, DTTC-4Cl was therefore synthesized by end-capping DTTC core with 2Cl-IC groups instead of 2F-IC groups. Moreover, DTTC-4Cl demonstrates a red-shifted absorption in comparison with DTTC-4F, which is beneficial for light-harvesting. Overall, PM6:DTTC-4Cl affords an outstanding PCE of 15.42% with a V-OC of 0.92 V, a J(SC) of 22.64 mA cm(-2) and a FF of 74.04%, which is the record PCE observed in carbazole-based NFAs.
Arbitrary control of the diffusion potential between a plasmonic metal and a semiconductor by an angstrom-thick interface dipole layer
(2020-01-21)
Oshikiri, Tomoya
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Sawayanagi, Hiroki
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Nakamura, Keisuke
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Ueno, Kosei
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Katase, Takayoshi
Localized surface plasmon resonances (LSPRs) are gaining considerable attention due to the unique far-field and near-field optical properties and applications. Additionally, the Fermi energy, which is the chemical potential, of plasmonic nanoparticles is one of the key properties to control hot-electron and -hole transfer at the interface between plasmonic nanoparticles and a semiconductor. In this article, we tried to control the diffusion potential of the plasmonic system by manipulating the interface dipole. We fabricated solid-state photoelectric conversion devices in which gold nanoparticles (Au-NPs) are located between strontium titanate (SrTiO3) as an electron transfer material and nickel oxide (NiO) as a hole transport material. Lanthanum aluminate as an interface dipole layer was deposited on the atomic layer scale at the three-phase interface of Au-NPs, SrTiO3, and NiO, and the effect was investigated by photoelectric measurements. Importantly, the diffusion potential between the plasmonic metal and a semiconductor can be arbitrarily controlled by the averaged thickness and direction of the interface dipole layer. The insertion of an only one unit cell (uc) interface dipole layer, whose thickness was less than 0.5 nm, dramatically controlled the diffusion potential formed between the plasmonic nanoparticles and surrounding media. This is a new methodology to control the plasmonic potential without applying external stimuli, such as an applied potential or photoirradiation, and without changing the base materials. In particular, it is very beneficial for plasmonic devices in that the interface dipole has the ability not only to decrease but also to increase the open-circuit voltage on the order of several hundreds of millivolts.
Pilot Study to Establish a Novel Five-Gene Biomarker Panel for Predicting Lymph Node Metastasis in Patients With Early Stage Endometrial Cancer
(2020-01-21)
Huang, Chia-Yen
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Liao, Kuang-Wen
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Chou, Chih-Hung
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Shrestha, Sirjana
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Yang, Chi-Dung
Introduction: In the United States and Europe, endometrial endometrioid carcinoma (EEC) is the most prevalent gynecologic malignancy. Lymph node metastasis (LNM) is the key determinant of the prognosis and treatment of EEC. A biomarker that predicts LNM in patients with EEC would be beneficial, enabling individualized treatment. Current preoperative assessment of LNM in EEC is not sufficiently accurate to predict LNM and prevent overtreatment. This pilot study established a biomarker signature for the prediction of LNM in early stage EEC. Methods: We performed RNA sequencing in 24 clinically early stage (T1) EEC tumors (lymph nodes positive and negative in 6 and 18, respectively) from Cathay General Hospital and analyzed the RNA sequencing data of 289 patients with EEC from The Cancer Genome Atlas (lymph node positive and negative in 33 and 256, respectively). We analyzed clinical data including tumor grade, depth of tumor invasion, and age to construct a sequencing-based prediction model using machine learning. For validation, we used another independent cohort of early stage EEC samples (n = 72) and performed quantitative real-time polymerase chain reaction (qRT-PCR). Finally, a PCR-based prediction model and risk score formula were established. Results: Eight genes (ASRGL1, ESR1, EYA2, MSX1, RHEX, SCGB2A1, SOX17, and STX18) plus one clinical parameter (depth of myometrial invasion) were identified for use in a sequencing-based prediction model. After qRT-PCR validation, five genes (ASRGL1, RHEX, SCGB2A1, SOX17, and STX18) were identified as predictive biomarkers. Receiver operating characteristic curve analysis revealed that these five genes can predict LNM. Combined use of these five genes resulted in higher diagnostic accuracy than use of any single gene, with an area under the curve of 0.898, sensitivity of 88.9%, and specificity of 84.1%. The accuracy, negative, and positive predictive values were 84.7, 98.1, and 44.4%, respectively. Conclusion: We developed a five-gene biomarker panel associated with LNM in early stage EEC. These five genes may represent novel targets for further mechanistic study. Our results, after corroboration by a prospective study, may have useful clinical implications and prevent unnecessary elective lymph node dissection while not adversely affecting the outcome of treatment for early stage EEC.
Investigation of the spectral characteristics of silicon-vacancy centers in ultrananocrystalline diamond nanostructures and single crystalline diamond
(2020-01-21)
Kunuku, Srinivasu
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Chen, Yen-Chun
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Chen, Chien-Hsu
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Kandasami, Asokan
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Chang, Wen-Hao
Silicon-vacancy (SiV) centers were produced in single crystalline diamond (SCD) and ultrananocrystalline diamond (UNCD) nanostructures via Si ion implantation or in situ Si doping. SiV-embedded UNCD (SiV-UNCD) was fabricated by both top-down and bottom-up methods. The spectral properties of the SiV centers, including the zero phonon line (ZPL) width and decay time, were investigated in the SCD and UNCD nanostructures. All the SiV-UNCD nanostructures showed bright emission regardless of the preparation method. However, the decay time of the SiV centers was affected by the synthesis procedure. A SiV decay time of tau similar to 0.19 ns was observed for UNCD nanostructures formed by in situ doping, whereas the SiV decay time was similar to 0.43 ns for SiV-UNCD clusters prepared by Si ion implantation into UNCD deposited on Ti/sapphire substrates. The ultrasonication of UNCD clusters on Ti/sapphire pyramids produced bright SiV-UNCD nanoclusters with sizes of similar to 50 nm, a ZPL width of 13.5 nm, and a decay time of 0.35 ns, suggesting promising potential in bioimaging applications. SiV-containing SCD (type Ia or type IIa) showed enhanced SiV spectral properties with a ZPL width of 6.08 nm and longer decay time of 1.3 ns. Published under license by AIP Publishing.
Finger-powered agglutination lab chip with CMOS image sensing for rapid point-of-care diagnosis applications
(2020-01-21)
Lu, Chung Hsiang
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Shih, Ting-Sheng
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Shih, Po-Chen
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Pendharkar, Gaurav Prashant
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Liu, Cheng-En
Agglutination is an antigen-antibody reaction with visible expression of aggregation of the antigens and their corresponding antibodies. Applications extend to the identification of acute bacterial infection, hemagglutination, such as blood grouping, and diagnostic immunology. Our finger-powered agglutination lab chip with external CMOS image sensing was developed to support a platform for inexpensive, rapid point-of-care (POC) testing applications related to agglutination effects. In this paper, blood grouping (ABO and Rh grouping) was utilized to demonstrate the function of our finger-powered agglutination lab chip with CMOS image sensing. Blood antibodies were preloaded into the antibody reaction chamber in the lab chip. The blood sample was pushed through the antibody reaction chamber using finger-powered pressure actuation to initiate a hemagglutination reaction to identify the blood type at the on-chip detection area using our homemade CMOS image sensing mini-system. Finger-powered actuation without the need for external electrical pumping is excellent for low-cost POC applications, but the pumping liquid volume per finger push is hard to control. In our finger-powered agglutination lab chip with CMOS image sensing, we minimized the effects of different finger push depths and achieved robust performance for the test results with different push depths. The driving sample volume per finger push is about 0.79 mm(3). For different chips and different pushes, the driven sample volume per finger push was observed to vary in the range of 0.64 to 1.18 mm(3). The red blood cells were separated from the plasma on-chip after the whole blood sample was finger pumped and before the red blood cells reached the antibody chamber via an embedded plasma-separation membrane. Our homemade CMOS image mini-system robustly read and identified the agglutination results on our agglutination lab chip.
Theoretical Study of the Kinetics of the Gas-Phase Reaction between Phenyl and Amino Radicals
(2020-01-21)
Pham, Tien, V
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Tue Trang, Hoang T.
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Trinh Le Huyen
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Tue Ngoc Nguyen
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交大名義發表
The potential energy surface (PES) of the C6H5 + NH2 reaction has been investigated by using ab initio CCSD(T)//B3LYP/ 6-311++G(3df,2p) calculations. The conventional transition-state theory (TST) and the variable reaction coordinate-TST (VRC-TST) have been used to predict the rate constants for the channels possessing tight and barrierless transition states, respectively. The Rice-Ramsperger-Kassel-Marcus/Master equation (RRKM/ME) theory has been utilized to determine the pressure-dependent rate constants for these reactions. The PES shows that the reaction begins with an exothermic barrierless addition of NH2 to C6H5 producing the vital intermediate state, namely, aniline (C6H5NH2, IS1). Once IS1 is generated, it can further isomerize to various intermediate states, which can give rise to different products, including PR4 (4,5,6-trihydro-1-amino phenyl + H-2), PR5 (3,4,5,6-tetrahydro phenyl + NH3), PR6 (2,3,5,6-tetrahydro-1-imidogen phenyl + H-2), PR9 (3,4,5,6-tetrahydro-1-imidogen phenyl + H-2), and PR10 (2,5,6-trihydro-1-amino phenyl + H-2), of which the most stable product, PR5, was formed by the most favorable channel going through the two advantageous transition states T1/11 (-28.9 kcal/mol) and T11P5 (-21.5 kcal/mol). The calculated rate constants for the low-energy channel, 1.37 x 10(-9) and 2.16 x 10(-11) cm(3) molecule(-1) s(-1) at T = 300, P = 1 Torr and T = 2000 K, P = 760 Torr, respectively, show that the title reaction is almost pressure-and temperature-dependent. The negative temperature-dependent rate coefficients can be expressed in the modified Arrhenius form of k(1) = 8.54 x 10(13) T-7.20 exp (-7.07 kcal.mol(-1)/RT) and k(2) = 2.42 x 10(15) T-7.61 exp (-7.75 kcal.mol(-1)/RT) at 1 and 10 Torr, respectively, and in the temperature range of 300-2000 K. The forward and reverse rate coefficients as well as the high-pressure equilibrium constants of the C6H5 + NH2 <-> IS1 process were also predicted; their values revealed that its kinetics do not depend on pressure at low temperature but strongly depend on pressure at high temperature. Moreover, the predicted formation enthalpies of reactants and the enthalpy changes of some channels are in good agreement with the experimental results.
Time-resolved FTIR study on the structural switching of human galectin-1 by light-induced disulfide bond formation
(2020-01-21)
Kuroi, Kunisato
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Kamijo, Mana
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Ueki, Mutsuki
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Niwa, Yusuke
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Hiramatsu, Hirotsugu
Disulfide bonds play a fundamental role in controlling the tertiary structure of proteins; the formation or cleavage of some disulfide bonds can switch the structures and/or functions of proteins. Human galectin-1 (hGal-1), which is a lectin protein, exemplifies how both structure and function are changed by disulfide bonds; the structure and sugar-binding ability of hGal-1 are altered by the formation and cleavage of its three intra-molecular disulfide bonds. In the present study, the dynamics of the structural change of hGal-1 by the formation of disulfide bonds were investigated by time-resolved FTIR spectroscopy combined with a modification in which its thiol groups (-SH) were replaced with S-nitrosylated groups (SNO). Photodissociation of NO from SNO in reduced hGal-1 induced disulfide bond formation and transformed it into the oxidised form. The structural change to the oxidised form involved three distinct kinetics with fast (<300 s), middle (similar to 600 s), and slow (similar to 6400 s) lifetimes. In an examination of hGal-1 in the lactose-bound form, structural changes owing to the release of substrate lactose were also observed upon disulfide bond formation. The present method using the photodissociation of NO is useful for monitoring the dynamics of structural changes following disulfide formation.
Effects of pillar size modulation on the magneto-structural coupling in self-assembled BiFeO3-CoFe2O4 heteroepitaxy
(2020-01-21)
Amrillah, Tahta
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Chen, Yu-Xun
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My Ngoc Duong
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Abdussalam, Wildan
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Simanjuntak, Firman Mangasa
The magneto-structural coupling of BiFeO3 (BFO)-CoFe2O4 (CFO)/LaAlO3 (LAO) heteroepitaxy with various lateral sizes of CFO pillars embedded in a BFO matrix was investigated. A structural phase transformation of the BFO matrix was observed when the pillar size of CFO was increased to exceed 200 nm. Such structural transformation led to modification of magneto-elastic coupling behavior and magnetic anisotropy in the BFO-CFO/LAO system. The flexibility of tuning the pillar size of CFO, and hence, the strain and interfacial effect on the multiferroic system have significant application implications in these functional oxide nanocomposites.
Conformal Electrodeposition of Co-Ni to Improve the Mechanical Properties of Three-Dimensional Ordered Macroporous Ni Films
(2020-01-22)
Wang, Guang-Ren
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Hung, Pei-Sung
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Chang, Shou-Yi
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Yang, Jenn-Ming
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Tseng, Yuan-Chieh
Three-dimensional ordered macroporous Ni films, known as Ni inverse opals, are fabricated via a template approach in which polystyrene (PS) microspheres (820 nm in diameter) are assembled in closely-packed colloidal crystals via a vertical electrophoresis process, followed by electroplating of Ni into the interstitial voids within the colloidal crystals and the selective removal of PS microspheres. To improve its mechanical strength, a conformal Ni-Co layer (45 similar to 64 nm) is electrodeposited on the skeletons of the Ni inverse opals by cyclic voltammetry. After coating, from nano-indentation tests, the hardness and reduced elastic modulus are enhanced considerably (172 similar to 220% for hardness; 72 similar to 79% for reduced elastic modulus), as compared to those of pristine inverse opals. After an annealing treatment for the interdiffusion of Ni and Co, the sample reveals an even stronger hardness. X-ray diffraction patterns indicate that the finite thickness of the inverse opals skeletons induces preferential growth of the (111) plane. In short, a combined effect of solid solution alloying, thickening of inverse opals skeletons for greater load bearing, and a predominant (111) plane is responsible for the improved mechanical strength of the Ni inverse opals. (C) 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.
Ballistic Impact Performance of SiC Ceramic-Dyneema Fiber Composite Materials
(2020-01-22)
Wu, Kai-Kuang
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Chen, Yu-Liang
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Yeh, Jau-Nan
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Chen, Wei-Lun
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Lin, Chia-Shih
This study investigated the ballistic resistance of a composite target plate fabricated by combining SiC ceramic with the Dyneema fiber. To achieve a light-weight target plate that conforms to the US National Institute of Justice level four (NIJ IV) standards, minimal areal density analysis was conducted to obtain the optimal SiC ceramic-Dyneema fiber thickness combination. This study used energy absorption to analyze the ballistic resistance of the target plates. To drastically reduce experimental costs, most of this work employed ANSYS/LS-DYNA software to conduct finite element numerical simulations. First, ballistic experiments that conformed to NIJ IV standards were conducted to verify the simulation parameter configurations. Subsequently, the correlation function of the relationship between the combined thickness of the composite material and its ballistic resistance was determined through the experimental design, which effectively reduced the simulation analysis time. According to simulation experiments and regression analysis, the equation for the relationship between the combined thickness of the composite material and its ballistic resistance was EA though there were limitations to its application. From the numerical analysis results, 8.1940 mm SiC ceramic and 6.9637 mm Dyneema fiber were determined to constitute the optimal thickness combination for a composite that features a minimal areal density and which conforms to NIJ IV standards. The combination was verified to be consistent with the numerical simulation analysis results.
Demographics of Pediatric OHCA Survivors With Postdischarge Diseases: A National Population-Based Follow-Up Study
(2020-01-24)
Lee, Tsung-Han
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Juan, I-Cheng
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Hsu, Hsiu-Ying
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Chen, Wen-Liang
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Huang, Cheng-Chieh
Background: Postdischarge diseases (PDDs) have been reported for adult survivors of out-of-hospital cardiac arrest (OHCA). However, the detailed demographics of pediatric OHCA survivors with PDDs are not well-documented, and information regarding functional survivors is particularly limited. We aimed to report detailed information on the PDDs of survivors of traumatic and non-traumatic pediatric OHCA using a national healthcare database. Methods: We retrospectively obtained data from the Taiwan government healthcare database (2011-2015). Information on the demographics of traumatic and non-traumatic pediatric OHCA survivors (<20 years) was obtained and reported. The patients who survived to discharge (survivors) and those classified as functional survivors were followed up for 1 year for the analysis of newly diagnosed PDDs. The time from discharge to PDD diagnosis was also reported. Results: A total of 2,178 non-traumatic and 288 traumatic OHCA pediatric cases were included. Among the non-traumatic OHCA survivors (n = 374, survival rate = 17.2%), respiratory tract (n = 270, 72.2%), gastrointestinal (n = 187, 50.0%), and neurological diseases (n = 167, 49.1%) were the three most common PDD categories, and in these three categories, the majority of PDDs were atypical/influenza pneumonia, non-infective acute gastroenteritis, and generalized/status epilepsy, respectively. Among the traumatic OHCA survivors (n = 21, survival rate = 7.3%), respiratory tract diseases (n = 17, 81.0%) were the most common, followed by skin or soft tissue (n = 14, 66.7%) diseases. Most functional survivors still suffered from neurological and respiratory tract diseases. Most PDDs, except for skin or soft tissue diseases, were newly diagnosed within the first 3 months after discharge. Conclusions: Respiratory tract (pneumonia), neurological (epilepsy), and skin or soft tissue (dermatitis) diseases were very common among both non-traumatic and traumatic OHCA survivors. More importantly, most PDDs, except for skin or soft tissue diseases, were newly diagnosed within the first 3 months after discharge.
Longitudinal and quantitative assessment platform for concurrent analysis of anti-tumor efficacy and cardiotoxicity of nano-formulated medication in vivo
(2020-01-25)
Tu, Wei-Ming
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Huang, Xin-Chun
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Chen, Yen-Ling
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Luo, Yun-Ling
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Liau, Ian
Increasing nanomedicinal approaches have been developed to effectively inhibit tumor growth; however, critical questions such as whether a nanomedicinal approach can mitigate latent side effects are barely addressed. To this end, we established a zebrafish xenograft tumor model, combining pseudodynamic three-dimensional cardiac imaging and image analysis to enable simultaneous and quantitative determination of the change of tumor volume and cardiac function of zebrafish upon specific nanoformulation treatment. Doxorubicin (DOX), a well-known chemotherapeutic agent with cardiotoxicity, and a recently developed DOX-loaded nanocomposite were employed as two model drugs to demonstrate the effectiveness to utilize the proposed evaluation platform for rapid validation. The nanoformulation significantly mitigated DOX-associated cardiotoxicity, while retaining the efficacy of DOX in inhibiting tumor growth compared to administration of carrier-free DOX at the same dose. We anticipate that this platform possesses the potential as an efficient assessment system for nanoformulated cancer therapeutics with suspected toxicity and side effects to vital organs such as the heart. (C) 2019 Elsevier B.V. All rights reserved.
Analysis of the back-barrier effect in AlGaN/GaN high electron mobility transistor on free-standing GaN substrates
(2020-01-25)
Liu, Xinke
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Wang, Hao-Yu
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Chiu, Hsien-Chin
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Chen, Yuxuan
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Li, Dabing
The effect of AlGaN back-barrier on AlGaN/GaN high electron mobility transistors (HEMTs) using freestanding GaN wafer has been investigated in this work. With the introducing back-barrier structure, the leakage path underneath the buffer (native nitrogen-vacancies and GaOx compounds of the HVPE-grown free-standing GaN surface) layer can be suppressed by lift-up the conduction band. As compared with AlGaN/GaN HEMTs on SiC wafer, AlGaN/GaN HEMTs on free-standing GaN wafer show enhanced drain current ( 700 mA/mm), improved transconductance (143 mS/mm), less current collapse (12%), higher current gain cut-off frequency (13 GHz), and maximum stable gain cut-off frequency (24 GHz), which is attributed to the higher epi quality layer on free-standing GaN wafer. (C) 2019 Elsevier B.V. All rights reserved.
Challenges in the design, planning and implementation of trials evaluating group interventions
(2020-01-29)
Biggs, Katie
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Hind, Daniel
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Gossage-Worrall, Rebecca
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Sprange, Kirsty
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White, David
Background Group interventions are interventions delivered to groups of people rather than to individuals and are used in healthcare for mental health recovery, behaviour change, peer support, self-management and/or health education. Evaluating group interventions in randomised controlled trials (RCTs) presents trialists with a set of practical problems, which are not present in RCTs of one-to-one interventions and which may not be immediately obvious. Methods Case-based approach summarising Sheffield trials unit's experience in the design and implementation of five group interventions. We reviewed participant recruitment and attrition, facilitator training and attrition, attendance at the group sessions, group size and fidelity aspects across five RCTs. Results Median recruitment across the five trials was 3.2 (range 1.7-21.0) participants per site per month. Group intervention trials involve a delay in starting the intervention for some participants, until sufficient numbers are available to start a group. There was no evidence that the timing of consent, relative to randomisation, affected post-randomisation attrition which was a matter of concern for all trial teams. Group facilitator attrition was common in studies where facilitators were employed by the health system rather than the by the grant holder and led to the early closure of one trial; research sites responded by training 'back-up' and new facilitators. Trials specified that participants had to attend a median of 62.5% (range 16.7%-80%) of sessions, in order to receive a 'therapeutic dose'; a median of 76.7% (range 42.9%-97.8%) received a therapeutic dose. Across the five trials, 75.3% of all sessions went ahead without the pre-specified ideal group size. A variety of methods were used to assess the fidelity of group interventions at a group and individual level across the five trials. Conclusion This is the first paper to provide an empirical basis for planning group intervention trials. Investigators should expect delays/difficulties in recruiting groups of the optimal size, plan for both facilitator and participant attrition, and consider how group attendance and group size affects treatment fidelity.
Structure-Dependent Photoluminescence in Low-Dimensional Ethylammonium, Propylammonium, and Butylammonium Lead Iodide Perovskites
(2020-01-29)
Lin, Chang-Wei
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Liu, Fangzhou
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Chen, Ting-Yang
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Lee, Kuan-Hua
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Chang, Chung-Kai
Hybrid organic-inorganic perovskites have attracted great attention as the next generation materials for photovoltaic and light-emitting devices. However, their environment instability issue remains as the largest challenge for practical applications. Recently emerging two-dimensional (2D) perovskites with Ruddlesden-Popper structures are found to greatly improve the stability and aging problems. Furthermore, strong confinement of excitons in these natural quantum-well structures results in the distinct and narrow light emission in the visible spectral range, enabling the development of spectrally tunable light sources. Besides the strong quasi-monochromatic emission, some 2D perovskites composed of the specific organic cations and inorganic layer structures emit a pronounced broadband emission. Herein, we report the light-emitting properties and the degradation of low-dimensional perovskites consisting of the three shortest alkylammonium spacers, mono-ethylammonium (EA), n-propylammonium (PA), and n-butylammonium (BA). While (BA)(2)PbI4 is known to form well-oriented 2D thin films consisting of layers of corner-sharing PbI6 octahedra separated by a bilayer of BA cations, EA with shorter alkyl chains tends to form other types of lower-dimensional structures. Nevertheless, optical absorption edges of asprepared fresh EAPbI(3), (PA)(2)PbI4, and (BA)(2)PbI4 are obviously blue-shifted to 2.4-2.5 eV compared to their 3D counterpart, methylammonium lead iodide (MAPbI(3)) perovskite, and they all emit narrow excitonic photoluminescence. Furthermore, by carefully optimizing deposition conditions, we have achieved a predominantly 2D structure for (PA)(2)PbI4. However, unlike (BA)(2)PbI4, upon exposure to ambient environment, (PA)(2)PbI4 readily transforms to a different crystal structure, exhibiting a prominently broadband light from similar to 500 to 800 nm and a gradual increase in intensity as structural transformation proceeds.
RiceTalk: Rice Blast Detection Using Internet of Things and Artificial Intelligence Technologies
(2020-02-01)
Chen, Wen-Liang
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Lin, Yi-Bing
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Ng, Fung-Ling
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Liu, Chun-You
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Lin, Yun-Wei
Rice blast is one of the most serious plant diseases. Many rice blast management approaches require know-how of experienced farmers or agronomists. Monitoring the farm for disease detection is labor intensive and time consuming. By using the Internet of Things (IoT) and artificial intelligence (AI), we are able to detect plant diseases more efficiently. Existing AI and IoT studies detect plant diseases by images or nonimage hyperspectral data, which require manual operations to obtain the photographs or data for analysis. Also, image detection typically is too late as rice blast may already spread to other plants. Based on an IoT platform for soil cultivation, we develop the RiceTalk project that utilizes nonimage IoT devices to detect rice blast. Unlike the image-based plant disease detection approaches, our agriculture sensors generate nonimage data that can be automatically trained and analyzed by the AI mechanism in real time. The beauty of RiceTalk is that the AI model is treated as an IoT device and is managed like other IoT devices. In this way, our approach significantly reduces the platform management cost to provide real-time training and predictions. We also propose an innovative spore germination mechanism as a new feature extraction model for agriculture. In the current implementation, the accuracy of the RiceTalk prediction on rice blast is 89.4%.
Discrimination of Severity of Alzheimer's Disease with Multiscale Entropy Analysis of EEG Dynamics
(2020-02-01)
Hsu, Chang Francis
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Chao, Hsuan-Hao
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Yang, Albert C.
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Yeh, Chih-Wei
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Hsu, Long
Multiscale entropy (MSE) was used to analyze electroencephalography (EEG) signals to differentiate patients with Alzheimer's disease (AD) from healthy subjects. It was found that the MSE values of the EEG signals from the healthy subjects are higher than those of the AD ones at small time scale factors in the MSE algorithm, while lower than those of the AD patients at large time scale factors. Based on the finding, we applied the linear discriminant analysis (LDA) to optimize the differentiating performance by comparing the resulting weighted sum of the MSE values under some specific time scales of each subject. The EEG data from 15 healthy subjects, 69 patients with mild AD, and 15 patients with moderate to severe AD were recorded. As a result, the weighted sum values are significantly higher for the healthy than the patients with moderate to severe AD groups. The optimal testing accuracy under five specific scales is 100% based on the EEG signals acquired from the T4 electrode. The resulting weighted sum value for the mild AD group is in the middle of those for the healthy and the moderate to severe AD groups. Therefore, the MSE-based weighted sum value can potentially be an index of severity of Alzheimer's disease.
Thermal Relaxation Spectra for Evaluating Luminescence Quantum Efficiency of CASN:Eu2+ Measured by Balanced-Detection Sagnac-Interferometer Photothermal Deflection Spectroscopy
(2020-02-01)
Chima, Hiromichi
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Shiokawa, Naoyuki
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Seto, Keisuke
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Takahashi, Kohsei
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Hirosaki, Naoto
Highly sensitive broadband photothermal spectroscopy with a white-light lamp as the excitation source was developed by combining a Sagnac interferometer and balanced detection with a photothermal deflection method. A probe beam was split by a birefringent crystal CaCO3 into signal and reference beams with a balanced intensity. This balanced detection enabled the measurement of photoexcited thermal relaxation spectra of materials in the air over the whole visible range in the weak excitation limit 50 mu W/cm(2). The photothermal excitation spectrum of Eu2+-doped CaAlSiN3 phosphors (CASN:Eu2+) with a high luminescent quantum efficiency was measured to be distinctly different from the photoluminescence excitation spectrum which reflects the absorption spectrum, revealing the thermal relaxation mechanism of the phosphor. Assuming a typical non-radiative relaxation from the higher excited states to the lowest excited state and successively to the ground state, it is demonstrated that the photoluminescence efficiency of the phosphors is readily evaluated simply by comparing the photothermal and photoluminescence excitation spectra.
Effects of surface inclination and type of surface roughness on the nucleate boiling heat transfer performance of HFE-7200 dielectric fluid
(2020-02-01)
Tran, Ngoctan
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Sajjad, Uzair
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Lin, Rick
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Wang, Chi-Chuan
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機械工程學系
In the present work, the effects of surface roughness (including roughness from machined roughness and sandblasted roughness), surface inclinations, and heat fluxes on the nucleate pool boiling heat transfer of HFE-7200 dielectric liquid at a working pressure of 1 atm. are examined in detail. Five aluminum surfaces, with different roughness from 0.45 mu m to 9 mu m, are employed as test samples. The nucleate boiling phenomenon is examined with the wall-superheat temperature ranging from 5 degrees C to 30 degrees C, and surface inclinations of 0 degrees, 90 degrees, and 180 degrees, respectively. SEM images and nucleate boiling bubbles captured by a high-speed camera are utilized for further analyses. For all cases in this study, it is found that the nucleate boiling heat transfer of the sandblasted rough surfaces is superior to those of the polished and machined rough surfaces. For instance, at a wall-superheat temperature of 30 degrees C and inclination angle of 0 degrees, the heat flux is augmented up to 69.7%, and 139.3% when compared to the polished surface for the sandblasted surfaces with the roughness of 6.2 mu m, and 9 mu m, respectively. In addition, novel correlations are also proposed for predicting the nucleate pool boiling heat transfer coefficient of HEF-7200 dielectric fluid with different surface roughness, inclinations and heat fluxes. (C) 2019 Elsevier Ltd. All rights reserved.
Highly efficient blue and white light-emitting electrochemical cells employing substrates containing embedded diffusive layers
(2020-02-01)
Chen, Yan-Zhi
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Luo, Dian
;
Hsiang, Chi-Haw
;
Yi, Rong-Huei
;
Lin, Ching-Hsuan
Enhancing device efficiencies of the blue and white light-emitting electrochemical cells (LECs) is realized by employing substrates with embedded diffusive layers containing scattering TiO2 nanoparticles (NPs). The diffusive layers can eliminate the influence of microcavity effect on the output electroluminescence (EL) spectrum and recover the intrinsic EL spectrum of the emissive layer. The emission zone positions of the blue and white LECs are estimated by fitting the measured EL spectra with the simulated EL spectra based on precisely tuned emission zone positions. Incorporating red-emitting guest dopant in the white LEC results in shifted emission zone toward the cathode due to enhanced electron trapping. The external quantum efficiency (EQE) of the blue and white LECs employing proper diffusive substrates can be enhanced by 260 and 210%, respectively. The maximal EQE (power efficiency) of the blue and white LECs reach 35.4% (83.4 lm W-1) and 22.0% (41.6 lm W-1), respectively. These promising device efficiencies confirm the potential applications for the proposed diffusive substrates in enhancing light extraction from LECs. In addition, adjusting the effective refractive index of the diffusive layer has distinct effect on different EL emission color. With well confined optical field of blue EL in indium tin oxide layer, lower effective refractive index of the diffusive layer results in higher refractive index difference between the scattering TiO2 NPs and the host medium, rendering higher scattering efficiency and more light extraction. In contrast, higher effective refractive index of the diffusive layer leads to unguided red EL extending into the diffusive layer and more light can be outcoupled. These results show that the effective refractive index of the diffusive layer should be judiciously chosen according to the emission color of EL to be extracted.