Toh Chun | UTM - Academia.edu (original) (raw)
Papers by Toh Chun
The trade-off between off-state leakage current and switching delay for impact-ionization MOS tra... more The trade-off between off-state leakage current and switching delay for impact-ionization MOS transistor (I-MOS) is pointed out and studied for the first time. This trade-off is unique for I-MOS devices, and is related to the self-amplifying carrier multiplication, the exact phenomenon used to be viewed as a merit. Monte-Carlo simulation is performed to study the random process of carrier multiplication in I-MOS, and the physical limit to the transistor switching delay is assessed. We found that at leakage constraints of 0.1muA/mum, silicon I-MOS shows long intrinsic switch-on delay (>10ps) and large random delay variance, hence does not show advantage in the delay/leakage trade-off compared to CMOS devices.
Silicon nano-wire impact ionization multiple-gate field-effect transistor (i-mugfet or I-FinFET) ... more Silicon nano-wire impact ionization multiple-gate field-effect transistor (i-mugfet or I-FinFET) with excellent subthreshold swing of less than 5 mV/decade at room temperature were demonstrated. Both n- and p- channel I-FinFET devices were realized. The multiple-gate structure enhances the gate-to-channel coupling effect and the impact-ionization rate in the fin or nanowire channel, thereby reducing the breakdown voltage and giving excellent device performance.
International Journal of Clinical Practice, 2008
This study was designed to assess the clinical usefulness of imaging for predicting the prognosis... more This study was designed to assess the clinical usefulness of imaging for predicting the prognosis of patients with combined hepatocellular cholangiocarcinoma (cHCC-CC). Between 1999 and 2004, 30 patients with histopathologically proven cHCC-CC underwent computed tomography (CT) or magnetic resonance imaging (MRI). The imaging data and survival were analysed. Univariate log-rank analysis of imaging findings revealed that tumour necrosis, bile duct invasion, major vascular branch invasion, multiplicity, bilobar distribution, regional lymph node involvement, regional organ invasion, distant metastasis and ascites had adverse influences on overall survival. Multivariate Cox proportional hazard analysis demonstrated that major vascular branch invasion, regional organ invasion, nodal and distant metastases were independent prognostic factors that adversely affected overall survival rates. Overall cumulative survival rates at 1, 3 and 5 years were 53%, 26% and 12%, respectively. Analysing the survival of our patients by using clinical stages of the newly updated American Joint Committee on Cancer (AJCC) classification for liver neoplasm based on the imaging findings, we found significant differences between stages I/II and III (p < 0.001) and between stages III and IV (p = 0.040). We conclude CT or MRI can be used to identify the prognostic factors and to estimate the outcomes of patients with cHCC-CC.
Nano Today, 2006
interact with cell surface receptors 1-4 . The interplay between cells and the ECM is a dynamic a... more interact with cell surface receptors 1-4 . The interplay between cells and the ECM is a dynamic and complex process where the physical and chemical properties of the ECM elicit different cellular responses 1,5 . An engineered substrate seeking to emulate the functions of the native ECM should, therefore, recapitulate its three dimensionality and nanofibrous topography, as well as its plethora of chemical motifs 6,7 . Advances in nanotechnology in recent years have enabled us to engineer novel biomaterials with these levels of complexities 7-9 . The eventual use of such complex biomaterials for specific applications will require an iterative process of understanding the mechanisms guiding cell-matrix interactions so that we can precisely control biomaterial properties to elicit desirable cellular responses . Here, we emphasize the importance of the three-dimensional nanofibrous features of extracellular environments in modulating cellular responses with local or subcellular resolutions in space-and timedependent manners. We also highlight state-of-the-art technologies to fabricate and characterize nanofibrous environments for relevant applications.
Japanese Journal of Applied Physics, 2008
... 2. Device Structure and Modeling Figure 1(a) shows the basic device structure of a Si ... 4).... more ... 2. Device Structure and Modeling Figure 1(a) shows the basic device structure of a Si ... 4). Kane's model has been employed in silicon tunnel FET and has shown good match between simulation ... temperatures.13) The bandgap of Si is modeled as a function of temperature and it ...
Deluged by completed genomic sequences, the need to align longer sequences becomes more urgent, a... more Deluged by completed genomic sequences, the need to align longer sequences becomes more urgent, and many more tools have thus become available. In the initial stage of sequence analysis, a biologist usually faces with the questions about how to choose the best tool to align sequences of interest and how to analyze and visualize the alignment results, and then with the question about whether unaligned regions produced by the tool are indeed not homologous or are just results due to inappropriate alignment tools or scoring systems used. Although several systematic evaluations of multiple sequence alignment programs have been proposed, they may not provide a standard-bearer for most biologists because those unaligned regions in these evaluations are never discussed. Thus, a tool that allows cross comparison of the alignment results obtained by different tools could help a biologist evaluate their correctness and accuracy.
European Neurology, 2010
To ascertain the characteristics of patients with sporadic Creutzfeldt-Jakob disease (CJD) and to... more To ascertain the characteristics of patients with sporadic Creutzfeldt-Jakob disease (CJD) and to determine the findings of electroencephalography (EEG) and brain magnetic resonance imaging (MRI). We pooled patients at a hospital from 2000 to 2008, and classified them according to WHO diagnostic criteria as having probable or possible CJD. We retrospectively analyzed their clinical manifestations, brain MRI, and EEG findings to evaluate correlations among them. In this study, 12 probable and 4 possible CJD patients were identified. Ten patients with probable CJD had asymmetric manifestations with hemiparesis, focal myoclonus, dystonia or apraxia; 9 had clinical manifestations mimicking the corticobasal syndrome. In contrast, neurological examinations did not show asymmetric signs in 4 patients with possible CJD. EEG showed a typical periodic sharp wave complex (PSWC) in 12 patients with probable CJD; most of them had bright signal intensity on diffusion-weighted imaging of the cortex and/or basal ganglia. There was a high tendency for asymmetric clinical manifestations that correlated with the presentation of PSWC and cortical lesions observed on the brain MRI scan. Our study indicates that asymmetric extrapyramidal symptoms/signs, in clinical features with characteristic abnormalities on MRI and EEG findings, might contribute to early diagnosis of sporadic CJD.
A simple and low cost logic based single poly Flash memory technology, NeoFlash®, with fast progr... more A simple and low cost logic based single poly Flash memory technology, NeoFlash®, with fast programming and high reliability is demonstrated in this paper. Programming with channel hot-hole-induced hot-electron injection and erasure with uniform channel Fowler-Nordheim tunneling are utilized to achieve fast programming, high endurance and good reliability characteristics. Owing to its simple cell structure and operation schemes, only 3 additional non-critical masks are needed, and the complexity of process integration and device tuning is much reduced. The SONOS based technology has been successfully embedded into 0.35μm ~ 65nm CMOS logic process. Because of electrons stored in nitride layer of ONO film, no tail bit during endurance and retention test is observed. As a result, NeoFlash® is a promising embedded Flash technology for SoC applications.
IEEE Transactions on Biomedical Engineering, 2011
An integrated CMOS ultrawideband wireless telemetry transceiver for wearable and implantable medi... more An integrated CMOS ultrawideband wireless telemetry transceiver for wearable and implantable medical sensor applications is reported in this letter. This high duty cycled, noncoherent transceiver supports scalable data rate up to 10 Mb/s with energy efficiency of 0.35 nJ/bit and 6.2 nJ/bit for transmitter and receiver, respectively. A prototype wireless capsule endoscopy using the proposed transceiver demonstrated in vivo image transmission of 640 × 480 resolution at a frame rate of 2.5 frames/s with 10 Mb/s data rate.
Rapid Communications in Mass Spectrometry, 2007
At present, metabolite profiling is of growing importance in herbal medicine fields such as breed... more At present, metabolite profiling is of growing importance in herbal medicine fields such as breeding, formulation, quality control and clinical trials. This preliminary study indicated that ultra-performance liquid chromatography/time-of-flight mass spectrometry (UPLC/TOFMS)-based metabolomics allows direct detection of down-stream derivatives of metabolites, arising from the herbal formulation process. This analytical approach allows the discrimination and tentative authentication of unique biomarkers related to different herbal extracts using unsupervised multivariate principal component analysis (PCA). The tentative identification of biomarkers is complemented significantly by the accurate mass measurement of TOFMS and the high resolution and high retention time reproducibility rendered by UPLC. The application of this approach in herbal extract discrimination and ginsenoside biomarker discovery of raw and steamed Panax notoginseng (Burk.) F.H. Chen is demonstrated and discussed. Copyright © 2007 John Wiley & Sons, Ltd.
The trade-off between off-state leakage current and switching delay for impact-ionization MOS tra... more The trade-off between off-state leakage current and switching delay for impact-ionization MOS transistor (I-MOS) is pointed out and studied for the first time. This trade-off is unique for I-MOS devices, and is related to the self-amplifying carrier multiplication, the exact phenomenon used to be viewed as a merit. Monte-Carlo simulation is performed to study the random process of carrier multiplication in I-MOS, and the physical limit to the transistor switching delay is assessed. We found that at leakage constraints of 0.1muA/mum, silicon I-MOS shows long intrinsic switch-on delay (>10ps) and large random delay variance, hence does not show advantage in the delay/leakage trade-off compared to CMOS devices.
Silicon nano-wire impact ionization multiple-gate field-effect transistor (i-mugfet or I-FinFET) ... more Silicon nano-wire impact ionization multiple-gate field-effect transistor (i-mugfet or I-FinFET) with excellent subthreshold swing of less than 5 mV/decade at room temperature were demonstrated. Both n- and p- channel I-FinFET devices were realized. The multiple-gate structure enhances the gate-to-channel coupling effect and the impact-ionization rate in the fin or nanowire channel, thereby reducing the breakdown voltage and giving excellent device performance.
International Journal of Clinical Practice, 2008
This study was designed to assess the clinical usefulness of imaging for predicting the prognosis... more This study was designed to assess the clinical usefulness of imaging for predicting the prognosis of patients with combined hepatocellular cholangiocarcinoma (cHCC-CC). Between 1999 and 2004, 30 patients with histopathologically proven cHCC-CC underwent computed tomography (CT) or magnetic resonance imaging (MRI). The imaging data and survival were analysed. Univariate log-rank analysis of imaging findings revealed that tumour necrosis, bile duct invasion, major vascular branch invasion, multiplicity, bilobar distribution, regional lymph node involvement, regional organ invasion, distant metastasis and ascites had adverse influences on overall survival. Multivariate Cox proportional hazard analysis demonstrated that major vascular branch invasion, regional organ invasion, nodal and distant metastases were independent prognostic factors that adversely affected overall survival rates. Overall cumulative survival rates at 1, 3 and 5 years were 53%, 26% and 12%, respectively. Analysing the survival of our patients by using clinical stages of the newly updated American Joint Committee on Cancer (AJCC) classification for liver neoplasm based on the imaging findings, we found significant differences between stages I/II and III (p < 0.001) and between stages III and IV (p = 0.040). We conclude CT or MRI can be used to identify the prognostic factors and to estimate the outcomes of patients with cHCC-CC.
Nano Today, 2006
interact with cell surface receptors 1-4 . The interplay between cells and the ECM is a dynamic a... more interact with cell surface receptors 1-4 . The interplay between cells and the ECM is a dynamic and complex process where the physical and chemical properties of the ECM elicit different cellular responses 1,5 . An engineered substrate seeking to emulate the functions of the native ECM should, therefore, recapitulate its three dimensionality and nanofibrous topography, as well as its plethora of chemical motifs 6,7 . Advances in nanotechnology in recent years have enabled us to engineer novel biomaterials with these levels of complexities 7-9 . The eventual use of such complex biomaterials for specific applications will require an iterative process of understanding the mechanisms guiding cell-matrix interactions so that we can precisely control biomaterial properties to elicit desirable cellular responses . Here, we emphasize the importance of the three-dimensional nanofibrous features of extracellular environments in modulating cellular responses with local or subcellular resolutions in space-and timedependent manners. We also highlight state-of-the-art technologies to fabricate and characterize nanofibrous environments for relevant applications.
Japanese Journal of Applied Physics, 2008
... 2. Device Structure and Modeling Figure 1(a) shows the basic device structure of a Si ... 4).... more ... 2. Device Structure and Modeling Figure 1(a) shows the basic device structure of a Si ... 4). Kane's model has been employed in silicon tunnel FET and has shown good match between simulation ... temperatures.13) The bandgap of Si is modeled as a function of temperature and it ...
Deluged by completed genomic sequences, the need to align longer sequences becomes more urgent, a... more Deluged by completed genomic sequences, the need to align longer sequences becomes more urgent, and many more tools have thus become available. In the initial stage of sequence analysis, a biologist usually faces with the questions about how to choose the best tool to align sequences of interest and how to analyze and visualize the alignment results, and then with the question about whether unaligned regions produced by the tool are indeed not homologous or are just results due to inappropriate alignment tools or scoring systems used. Although several systematic evaluations of multiple sequence alignment programs have been proposed, they may not provide a standard-bearer for most biologists because those unaligned regions in these evaluations are never discussed. Thus, a tool that allows cross comparison of the alignment results obtained by different tools could help a biologist evaluate their correctness and accuracy.
European Neurology, 2010
To ascertain the characteristics of patients with sporadic Creutzfeldt-Jakob disease (CJD) and to... more To ascertain the characteristics of patients with sporadic Creutzfeldt-Jakob disease (CJD) and to determine the findings of electroencephalography (EEG) and brain magnetic resonance imaging (MRI). We pooled patients at a hospital from 2000 to 2008, and classified them according to WHO diagnostic criteria as having probable or possible CJD. We retrospectively analyzed their clinical manifestations, brain MRI, and EEG findings to evaluate correlations among them. In this study, 12 probable and 4 possible CJD patients were identified. Ten patients with probable CJD had asymmetric manifestations with hemiparesis, focal myoclonus, dystonia or apraxia; 9 had clinical manifestations mimicking the corticobasal syndrome. In contrast, neurological examinations did not show asymmetric signs in 4 patients with possible CJD. EEG showed a typical periodic sharp wave complex (PSWC) in 12 patients with probable CJD; most of them had bright signal intensity on diffusion-weighted imaging of the cortex and/or basal ganglia. There was a high tendency for asymmetric clinical manifestations that correlated with the presentation of PSWC and cortical lesions observed on the brain MRI scan. Our study indicates that asymmetric extrapyramidal symptoms/signs, in clinical features with characteristic abnormalities on MRI and EEG findings, might contribute to early diagnosis of sporadic CJD.
A simple and low cost logic based single poly Flash memory technology, NeoFlash®, with fast progr... more A simple and low cost logic based single poly Flash memory technology, NeoFlash®, with fast programming and high reliability is demonstrated in this paper. Programming with channel hot-hole-induced hot-electron injection and erasure with uniform channel Fowler-Nordheim tunneling are utilized to achieve fast programming, high endurance and good reliability characteristics. Owing to its simple cell structure and operation schemes, only 3 additional non-critical masks are needed, and the complexity of process integration and device tuning is much reduced. The SONOS based technology has been successfully embedded into 0.35μm ~ 65nm CMOS logic process. Because of electrons stored in nitride layer of ONO film, no tail bit during endurance and retention test is observed. As a result, NeoFlash® is a promising embedded Flash technology for SoC applications.
IEEE Transactions on Biomedical Engineering, 2011
An integrated CMOS ultrawideband wireless telemetry transceiver for wearable and implantable medi... more An integrated CMOS ultrawideband wireless telemetry transceiver for wearable and implantable medical sensor applications is reported in this letter. This high duty cycled, noncoherent transceiver supports scalable data rate up to 10 Mb/s with energy efficiency of 0.35 nJ/bit and 6.2 nJ/bit for transmitter and receiver, respectively. A prototype wireless capsule endoscopy using the proposed transceiver demonstrated in vivo image transmission of 640 × 480 resolution at a frame rate of 2.5 frames/s with 10 Mb/s data rate.
Rapid Communications in Mass Spectrometry, 2007
At present, metabolite profiling is of growing importance in herbal medicine fields such as breed... more At present, metabolite profiling is of growing importance in herbal medicine fields such as breeding, formulation, quality control and clinical trials. This preliminary study indicated that ultra-performance liquid chromatography/time-of-flight mass spectrometry (UPLC/TOFMS)-based metabolomics allows direct detection of down-stream derivatives of metabolites, arising from the herbal formulation process. This analytical approach allows the discrimination and tentative authentication of unique biomarkers related to different herbal extracts using unsupervised multivariate principal component analysis (PCA). The tentative identification of biomarkers is complemented significantly by the accurate mass measurement of TOFMS and the high resolution and high retention time reproducibility rendered by UPLC. The application of this approach in herbal extract discrimination and ginsenoside biomarker discovery of raw and steamed Panax notoginseng (Burk.) F.H. Chen is demonstrated and discussed. Copyright © 2007 John Wiley & Sons, Ltd.