Browsing by Issue Date, starting with "2020-02-01"

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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
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Hsiang, Chi-Haw
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Yi, Rong-Huei
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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.
Abnormal High Resistive State Current Mechanism Transformation in Ti/HfO2/TiN Resistive Random Access Memory
(2020-02-01)
Zhou, Kuan-Ju
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Chang, Ting-Chang
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Lin, Chih-Yang
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Chen, Chun-Kuei
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Tseng, Yi-Ting
In this letter, the electrical characteristics of Ti/HfO2/TiN resistive random access memory (RRAM) were thoroughly investigated. An abnormal current degradation was seen in the DC sweeping cycle. Both the on-state and off-state current clearly exhibited degradation with time. Next, current fitting analysis was used to investigate the carrier transport mechanisms. The results indicate that the on-state carrier transport mechanism changed from space-charge-limited current into hopping conduction after cycle sweeping. However, the off-state current changes from Schottky thermal emission to hopping conduction. Based on comparisons of different Schottky distances and Schottky barriers, physical models were proposed to explain the abnormal current degradation behavior. Finally, COMSOL electric field simulations were used to show the electric field distribution around the conducting filament (CF), and the conducting model was subsequently verified.
Strengthening long-term job performance: The moderating roles of sense of responsibility and leader's support
(2020-02-01)
Lin, Chieh-Peng
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Tsai, Meng-Keng
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交大名義發表
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National Chiao Tung University
Drawing upon human capital theory and attachment theory, this study develops a research model that examines how on-the-job training (OJT) effectiveness and work engagement play key mediating roles in the development of job performance. In the proposed model, job performance is indirectly influenced by cultural learning, professional learning, and mentorship learning via the full mediation of OJT effectiveness. At the same time, job performance is also influenced by social interaction, leader support, and self-efficacy via the full mediation of work engagement. Employees' sense of responsibility and leader support both play moderating roles in the research model. The hypotheses were empirically tested using both primary data from a survey on new employees of a leading financial holding company in Taiwan's banking industry and secondary data from the company's database of human resource management (HRM) regarding the training and education of the new employees. JEL Classification: D23, M53, O15
Spontaneously Micropatterned Silk/Gelatin Scaffolds with Topographical, Biological, and Electrical Stimuli for Neuronal Regulation
(2020-02-01)
Lin, Chun-Chang
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Chang, Jing-Jing
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Yung, Ming-Chi
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Huang, Wei-Chen
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Chen, San-Yuan
Effective integration of stimulation and direction in bionic scaffolds by materials and microstructure design has been the focus in the advancement of nerve regeneration. Hydrogels are the most promising biomimicked materials used in developing nerve grafts, but the highly hydrated networks limit the fabrication of hydrogel materials into complex biomedical devices. Herein, facile lithography-free and spontaneously micropatterned techniques were used to fabricate a smart protein hydrogel-based scaffold, which carried topographical, electrical, and chemical induction for neural regulation. The synthesized tissue-mimicked silk-gelatin (SG)/polylactic acid bilayer system can self-form three-dimensional ordered corrugation micropatterns with well-defined dimensions (wavelength, lambda) based on the stress-induced topography. Through magnetically and topographically guided deposition of the synthesized nerve growth factor-incorporated Fe3O4-graphene nanoparticles (GFPNs), a biologically and electrically conductive cell passage with one-dimensional directionality was constructed to allow for a controllable constrained geometric effect on neuronal adhesion, differentiation, and neurite orientation. Particularly, the SG with corrugation patterns of lambda approximate to 30 mu m resulted in the optimal cell adhesion and differentiation in response to the pattern guidance. Furthermore, the additional electrical stimulation applied on GFPN-deposited SG resulted in a 1.5-fold increase in the neurite elongation by day 7, finally leading to the neuronal connection by day 21. Such a hydrogel device with synergistic effects of physical and chemical enhancement on neuronal activity provides an expectable opportunity in the development of next-generation nerve conduits.
Multi-color optical microscopy using modulated excitation lasers and single-frequency demux
(2020-02-01)
Wang, Nan
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Kobayashi, Takayoshi
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Ruan, Shuangchen
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電機學院
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College of Electrical and Computer Engineering
Multi-color microscopy has been a powerful tool for industrial and biomedical applications. Traditionally, image acquisition through different color channels has to be carried out separately using a single detector for sequential detection or multi-detectors for simultaneous detection. This costly and complex process may introduce colocalization errors due to the alignment. This paper describes a compact multi-color microscope using modulated excitation lasers and a single electronic frequency demux for signal detection. To mark fluorescence from different labels in the sample separately, the excitation lasers are intensity modulated with different frequencies. After fluorescence is detected, the electronic signals are demultiplexed with a single spectrum analyzer. This method allows the realization of multi-color imaging with minimal amount of detection elements. Multi-color imaging of fluorescent spheres, gold nanoparticles, and biological tissues are carried out. A fiber-coupling system has also been used to simplify the optical alignments, while its focal chromatic aberration has been characterized.
Control of matrix stiffness promotes endodermal lineage specification by regulating SMAD2/3 via lncRNA LINC00458
(2020-02-01)
Chen, Yu-Fan
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Li, Yi-Shuan J.
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Chou, Chih-Hung
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Chiew, Men Yee
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Huang, Hsien-Da
During endoderm formation, cell identity and tissue morphogenesis are tightly controlled by cell-intrinsic and cell-extrinsic factors such as biochemical and physical inputs. While the effects of biochemical factors are well studied, the physical cues that regulate cell division and differentiation are poorly understood. RNA sequencing analysis demonstrated increases of endoderm-specific gene expression in hPSCs cultured on soft substrate (Young's modulus, 3 +/- 0.45 kPa) in comparison with hard substrate (Young's modulus, 165 +/- 6.39 kPa). Further analyses revealed that multiple long noncoding RNAs (lncRNAs) were up-regulated on soft substrate; among them, LINC00458 was identified as a stiffness-dependent lncRNA specifically required for hPSC differentiation toward an early endodermal lineage. Gain- and loss-of-function experiments confirmed that LINC00458 is functionally required for hPSC endodermal lineage specification induced by soft substrates. Our study provides evidence that mechanical cues regulate the expression of LINC00458 and induce differentiation of hPSC into hepatic lineage progenitors.
A Lucky Encounter that Triggered a Leap
(2020-02-01)
Tobe, Yoshito
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應用化學系
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Department of Applied Chemistry
A fast fused part-based model with new deep feature for pedestrian detection and security monitoring
(2020-02-01)
Cheng, Eric Juwei
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Prasad, Mukesh
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Yang, Jie
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Khanna, Pritee
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Chen, Bing-Hong
In recent years, pedestrian detection based on computer vision has been widely used in intelligent transportation, security monitoring, assistance driving and other related applications. However, one of the remaining open challenges is that pedestrians are partially obscured and their posture changes. To address this problem, deformable part model (DPM) uses a mixture of part filters to capture variation in view point and appearance and achieves success for challenging datasets. Nevertheless, the expensive computation cost of DPM limits its ability in the real-time application. This study propose a fast fused part-based model (FFPM) for pedestrian detection to detect the pedestrians efficiently and accurately in the crowded environment. The first step of the proposed method trains six Adaboost classifiers with Haar-like feature for different body parts (e.g., head, shoulders, and knees) to build the response feature maps. These six response feature maps are combined with full-body model to produce spatial deep features. The second step of the proposed method uses the deep features as an input to support vector machine (SVM) to detect pedestrian. A variety of strategies is introduced in the proposed model, including part-based to full-body method, spatial filtering, and multi-ratios combination. Experiment results show that the proposed FFPM method improves the computation speed of DPM and maintains the performance in detection. (C) 2019 Elsevier Ltd. All rights reserved.
Influence of Post-Annealing on the Structural and Nanomechanical Properties of Co Thin Films
(2020-02-01)
Hwang, Yeong-Maw
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Pan, Cheng-Tang
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Lu, Ying-Xu
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Jian, Sheng-Rui
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Chang, Huang-Wei
The correlations between the microstructure and nanomechanical properties of a series of thermal annealed Co thin films were investigated. The Co thin films were deposited on glass substrates using a magnetron sputtering system at ambient conditions followed by subsequent annealing conducted at various temperatures ranging from 300 degrees C to 800 degrees C. The XRD results indicated that for annealing temperature in the ranged from 300 degrees C to 500 degrees C, the Co thin films were of single hexagonal close-packed (hcp) phase. Nevertheless, the coexistence of hcp-Co (002) and face-centered cubic (fcc-Co (111)) phases was evidently observed for films annealed at 600 degrees C. Further increasing the annealing temperature to 700 degrees C and 800 degrees C, the films evidently turned into fcc-Co (111). Moreover, significant variations in the hardness and Young's modulus are observed by continuous stiffness nanoindentation measurement for films annealed at different temperatures. The correlations between structures and properties are discussed.
Current-Aware Flash Scheduling for Current Capping in Solid State Disks
(2020-02-01)
Chang, Li-Pin
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Cheng, Chia-Hsiang
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Chang, Shu-Ting
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Chou, Po-Han
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資訊工程學系
Solid state disks (SSDs) employ internal parallelism to boost their input/output (I/O) performance, but a high degree of flash parallelism inevitably consumes a high level of current. To budget power or support multiple power sources, system software may force an SSD into a new power mode that has a specific current supply limit. This paper introduces a firmware approach to optimize SSD internal parallelism subject to a current supply limit. The proposed method involves two steps. First, we constructed current models of flash operations on the basis of real-world measurement results. Second, we designed a firmware scheduler to determine the actual starting time of each flash operation. The proposed scheduler accounted for flash aging, process variation, and internal resource contention, and it avoided any current cap violation by checking a few time points instead of every unit of time. Our experimental results indicated that the proposed approach outperformed existing methods with respect to I/O response time and throughput under realistic workloads.
Effect of Seed Layer on Gate-All-Around Poly-Si Nanowire Negative-Capacitance FETs With MFMIS and MFIS Structures: Planar Capacitors to 3-D FETs
(2020-02-01)
Lee, Shen-Yang
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Chen, Han-Wei
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Shen, Chiuan-Huei
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Kuo, Po-Yi
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Chung, Chun-Chih
In this article, we successfully fabricated nanowire (NW) negative capacitance (NC)-related ferroelectric FETs (FE-FETs) with two structures: trigate (TG) and gate-all-around (GAA). Planar capacitors with a metal-FE-metal (MFM) structure were investigated first. Post-metal annealing (PMA) at 700 resulted in the best ferroelectricity. This condition was considerably different from that of directly stacking onto NWs because of the difference in size and curvature between planar and TG or GAA structures. Because of the addition of an underlying ZrO2 seed layer, Hf ZrxO2 in the gate-stack has been crystallized before the PMA process. In addition, two different gate-stack configurations, MFM-insulator-semiconductor (MFMIS) and metal-FE-insulator-semiconductor (MFIS), were investigated for the GAA structure. We determined that MFMIS displayed considerably more favorable subthreshold behavior and ON-state current compared with MFIS. NC-related phenomena, such as negative drain-induced barrier lowering and negative differential resistance, were observed.
Investigation of Recessed Gate AlGaN/GaN MIS-HEMTs with Double AlGaN Barrier Designs toward an Enhancement-Mode Characteristic
(2020-02-01)
Wu, Tian-Li
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Tang, Shun-Wei
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Jiang, Hong-Jia
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國際半導體學院
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International College of Semiconductor Technology
In this work, recessed gate AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) with double AlGaN barrier designs are fabricated and investigated. Two different recessed depths are designed, leading to a 5 nm and a 3 nm remaining bottom AlGaN barrier under the gate region, and two different Al% (15% and 20%) in the bottom AlGaN barriers are designed. First of all, a double hump trans-conductance (g(m))-gate voltage (V-G) characteristic is observed in a recessed gate AlGaN/GaN MIS-HEMT with a 5 nm remaining bottom Al0.2Ga0.8N barrier under the gate region. Secondly, a physical model is proposed to explain this double channel characteristic by means of a formation of a top channel below the gate dielectric under a positive V-G. Finally, the impacts of Al% content (15% and 20%) in the bottom AlGaN barrier and 5 nm/3 nm remaining bottom AlGaN barriers under the gate region are studied in detail, indicating that lowering Al% content in the bottom can increase the threshold voltage (V-TH) toward an enhancement-mode characteristic.
Efficient and Portable Workgroup Size Tuning
(2020-02-01)
Yu, Chia-Lin
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Tsao, Shiao-Li
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資訊工程學系
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Department of Computer Science
The performance of an OpenCL program is strongly influenced by both hardware and software attributes. To achieve superior performance, developers may leverage automatic performance tuning techniques to determine the optimal parameters on the target device. Although existing approaches have shown promising tuning results in their target scenarios, other requirements such as efficiency, portability, and usability should also be considered because of the rapid growth of heterogeneous computing applications and platforms. In this paper, we re-examine the workgroup size tuning problem and propose a novel approach to meet the aforementioned requirements. We abstract the architectural details into a set of hardware parameters so that the proposed approach can be applied without the presence of target devices, which makes it more accessible to developers. The proposed approach is evaluated on 20 OpenCL kernels and six devices, including both CPUs and GPUs. Experimental results demonstrate that, with negligible overhead, our approach filters out 88.6 percent of the possible workgroup sizes on average. Among all the workgroup size candidates, the best- and worst-performing candidates can achieve average performance of 95.5 and 92.1 percent, respectively, compared with the optimal workgroup size.
The Effect of Solvent Vapor Annealing on Drug-Loaded Electrospun Polymer Fibers
(2020-02-01)
Chiu, Yu-Jing
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Zhang, Ziwei
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Dziemidowicz, Karolina
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Nikoletopoulos, Christos-Georgios
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Angkawinitwong, Ukrit
Electrospinning has emerged as a powerful strategy to develop controlled release drug delivery systems but the effects of post-fabrication solvent vapor annealing on drug-loaded electrospun fibers have not been explored to date. In this work, electrospun poly(epsilon-caprolactone) (PCL) fibers loaded with the hydrophobic small-molecule spironolactone (SPL) were explored. Immediately after fabrication, the fibers are smooth and cylindrical. However, during storage the PCL crystallinity in the fibers is observed to increase, demonstrating a lack of stability. When freshly-prepared fibers are annealed with acetone vapor, the amorphous PCL chains recrystallize, resulting in the fiber surfaces becoming wrinkled and yielding shish-kebab like structures. This effect does not arise after the fibers have been aged. SPL is found to be amorphously dispersed in the PCL matrix both immediately after electrospinning and after annealing. In vitro dissolution studies revealed that while the fresh fibers show a rapid burst of SPL release, after annealing more extended release profiles are observed. Both the rate and extent of release can be varied through changing the annealing time. Further, the annealed formulations are shown to be stable upon storage.
Near infrared radiation shielding using CsxWO3 nanoparticles for infrared mini light-emitting diodes
(2020-02-01)
Li, Chi-Ping
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Kang, Chieh-Yu
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Huang, Shu-Ling
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Lee, Po-Tsung
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Kuo, Hao-Chung
Recently, near infrared LEDs have been used in small electronic devices due to the trend of manufacturing compact systems. The intensity of near infrared (NIR) optical device needs to be moderated if the chip emits too much power. In tradition, color pigments are used as additives in the encapsulant of LEDs to reduce the intensity of over irradiated NIR, a strategy which results in unaesthetic appearance. Cesium doped tungsten trioxide (CsxWO3) nanoparticles (NPs) have good near infrared absorption ability. Applying very few amount of CsxWO3 NPs into the encapsulation materials of NIR optical device can decrease NIR intensity while still maintain high visible light transmittance without losing aesthetic touch of those devices such as LED transmitters. The addition of only 0.0021 wt% CsxWO3/PMA dispersion in epoxy encapsulant can drop 15.5% NIR (860 nm) intensity but barely reduce visible light (only 3.2% at 450 nm). The excellent performance of CsxWO3 NPs; i.e., good NIR absorption and visible light transmission properties, can be suitable for maintaining the moderate luminescence intensity of small optoelectronic devices like NIR mini- or micro- light-emitting diodes. (C) 2019 Elsevier B.V. All rights reserved.
Effects of ondansetron on apamin-sensitive small conductance calcium-activated potassium currents in pacing-induced failing rabbit hearts
(2020-02-01)
Yin, Dechun
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Yang, Na
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Tian, Zhipeng
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Wu, Adonis Z.
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Xu, Dongzhu
BACKGROUND Ondansetron, a widely prescribed antiemetic, has been implicated in drug-induced long QT syndrome. Recent patch clamp experiments have shown that ondansetron inhibits the apamin-sensitive small conductance calcium-activated potassium current (I-KAS). OBJECTIVE The purpose of this study was to determine whether ondansetron causes action potential duration (APD) prolongation by I-KAS inhibition. METHODS Optical mapping was performed in rabbit hearts with pacing-induced heart failure (HF) and in normal hearts before and after ondansetron (100 nM) infusion. APD at 80% repolarization (APD(80)) and arrhythmia inducibility were determined. Additional studies with ondansetron were performed in normal hearts perfused with hypokalemic Tyrode's (2.4 mM) solution before or after apamin administration. RESULTS The corrected QT interval in HF was 326 ms (95% confidence interval [CI] 306-347 ms) at baseline and 364 ms (95% CI 351-378 ms) after ondansetron infusion (P < .001). Ondansetron significantly prolonged APD(80) in the HF group and promoted early afterdepolarizations, steepened the APD restitution curve, and increased ventricular vulnerability. Ventricular fibrillation was not inducible in HF ventricles at baseline, but after ondansetron infusion, ventricular fibrillation was induced in 5 of the 7 ventricles (P = .021). In hypokalemia, apamin prolonged APD(80) from 163 ms (95% CI 146-180 ms) to 180 ms (95% CI 156-204 ms) (P = .018). Subsequent administration of ondansetron failed to further prolong APD(80) (180 ms [95% CI 156-204 ms] vs 179 ms [95% CI 165-194 ms]; P = .789). The results were similar when ondansetron was administered first, followed by apamin. CONCLUSION Ondansetron is a specific I-KAS blocker at therapeutic concentrations. Ondansetron may prolong the QT interval in HF by inhibiting small conductance calcium-activated potassium channels, which increases the vulnerability to ventricular arrhythmias.