Cryptographic transistor for true random number generator with low power consumption.

We design a cryptographic transistor (cryptoristor)-based true random number generator (tRNG) with low power consumption and small footprint. This is the first attempt to use irregular and unpredictable operation-induced randomness of a cryptoristor as an entropy source. To extract discrete random numbers with a binary code from the cryptoristor, we developed a noise-coupling analog-to-digital converter. This converter not only converts analog signals to digital random bits but also improves the randomness of the entropy source with low power consumption. The randomness of the cryptoristor is attributed to the random carrier multiplications with the creation and stochastic carrier escape as destruction, which occurs iteratively as long as the input current is fed. The cryptoristor-based tRNG passed 15 randomness test suites of NIST Special Publication 800-22. It is robust to iterative operational stresses and to ambient temperature changes, making it an attractive option for hardware-based security solutions in the Internet of Things due to its low power consumption and small size.

The gate injection-based field-effect synapse transistor with linear conductance update for online training.

Neuromorphic computing, an alternative for von Neumann architecture, requires synapse devices where the data can be stored and computed in the same place. The three-terminal synapse device is attractive for neuromorphic computing due to its high stability and controllability. However, high nonlinearity on weight update, low dynamic range, and incompatibility with conventional CMOS systems have been reported as obstacles for large-scale crossbar arrays. Here, we propose the CMOS compatible gate injection-based field-effect transistor employing thermionic emission to enhance the linear conductance update. The dependence of the linearity on the conduction mechanism is examined by inserting an interfacial layer in the gate stack. To demonstrate the conduction mechanism, the gate current measurement is conducted under varying temperatures. The device based on thermionic emission achieves superior synaptic characteristics, leading to high performance on the artificial neural network simulation as 93.17% on the MNIST dataset.

Synaptic Segmented Transistor with Improved Linearity by Schottky Junctions and Accelerated Speed by Double-Layered Nitride.

Neuromorphic devices have been extensively studied to overcome the limitations of a von Neumann system for artificial intelligence. A synaptic device is one of the most important components in the hardware integration for a neuromorphic system because a number of synaptic devices can be connected to a neuron with compactness as high as possible. Therefore, synaptic devices using silicon-based memory, which are advantageous for a high packing density and mass production due to matured fabrication technologies, have attracted considerable attention. In this study, a segmented transistor devoted to an artificial synapse is proposed for the first time to improve the linearity of the potentiation and depression (P/D). It is a complementary metal oxide semiconductor (CMOS)-compatible device that harnesses both non-ohmic Schottky junctions of the source and drain for improved weight linearity and double-layered nitride for enhanced speed. It shows three distinct and unique segments in drain current-gate voltage transfer characteristics induced by Schottky junctions. In addition, the different stoichiometries of SixNy for a double-layered nitride is utilized as a charge trap layer for boosting the operation speed. This work can bring the industry potentially one step closer to realizing the mass production of hardware-based synaptic devices in the future.

Cointegration of single-transistor neurons and synapses by nanoscale CMOS fabrication for highly scalable neuromorphic hardware.

Cointegration of multistate single-transistor neurons and synapses was demonstrated for highly scalable neuromorphic hardware, using nanoscale complementary metal-oxide semiconductor (CMOS) fabrication. The neurons and synapses were integrated on the same plane with the same process because they have the same structure of a metal-oxide semiconductor field-effect transistor with different functions such as homotype. By virtue of 100% CMOS compatibility, it was also realized to cointegrate the neurons and synapses with additional CMOS circuits. Such cointegration can enhance packing density, reduce chip cost, and simplify fabrication procedures. The multistate single-transistor neuron that can control neuronal inhibition and the firing threshold voltage was achieved for an energy-efficient and reliable neural network. Spatiotemporal neuronal functionalities are demonstrated with fabricated single-transistor neurons and synapses. Image processing for letter pattern recognition and face image recognition is performed using experimental-based neuromorphic simulation.

Gateless and Capacitorless Germanium Biristor with a Vertical Pillar Structure.

For the first time, a novel germanium (Ge) bi-stable resistor (biristor) with a vertical pillar structure was implemented on a bulk substrate. The basic structure of the Ge pillar-typed biristor is a p-n-p bipolar junction transistor (BJT) with an open base (floating), which is equivalent to a gateless p-channel metal oxide semiconductor field-effect transistor (MOSFET). In the pillar formation, we adopted an amorphous carbon layer to protect the Ge surface from both physical and chemical damage by subsequent processes. A hysteric current-voltage (I-V) characteristic, which results in a sustainable binary state, i.e., high current and low current at the same voltage, can be utilized for a memory device. A lower operating voltage with high current was achieved, compared to a Si biristor, due to the low energy bandgap of pure Ge.

Ternary logic decoder using independently controlled double-gate Si-NW MOSFETs.

A ternary logic decoder (TLD) is demonstrated with independently controlled double-gate (ICDG) silicon-nanowire (Si-NW) MOSFETs to confirm a feasibility of mixed radix system (MRS). The TLD is essential component for realization of the MRS. The ICDG Si-NW MOSFET resolves the limitations of the conventional multi-threshold voltage (multi-Vth) schemes required for the TLD. The ICDG Si-NW MOSFETs were fabricated and characterized. Afterwards, their electrical characteristics were modeled and fitted semi-empirically with the aid of SILVACO ATLAS TCAD simulator. The circuit performance and power consumption of the TLD were analyzed using ATLAS mixed-mode TCAD simulations. The TLD showed a power-delay product of 35 aJ for a gate length (LG) of 500 nm and that of 0.16 aJ for LG of 14 nm. Thanks to its inherent CMOS-compatibility and scalability, the TLD based on the ICDG Si-NW MOSFETs would be a promising candidate for a MRS using ternary and binary logic.

Loop-Mediated Isothermal Amplification (LAMP)-Based Turn on Fluorescent Paper (ToFP) Device for Detecting Rosellinia necatrix.

White root rot (WRR) disease caused by Rosellinia necatrix, a fungal pathogen, results in severe damage to various fruit trees, decreasing their marketability. Regular monitoring is a major process because the pathogen can remain in the soil around the host for a long time. Loop-mediated isothermal amplification (LAMP) is a highly sensitive and efficient amplification technology of nucleic acids (DNA or RNA) that can be performed at constant temperatures. Thus, it has been spotlighted as a useful tool for detecting several infectious agents. In the present study, LAMP-based Turn-on Fluorescent Paper (ToFP) devices were designed and applied to detect R. necatrix. LAMP conditions were optimized and found to be optimal at a reaction temperature (62 °C) and a reaction time (30 minutes). These reaction conditions were confirmed by applying them to infectious soil samples collected from the field. The limitation of detection was identified as 10 fg of genomic DNA under optimized LAMP conditions. These LAMP-based ToFP devices were generated with easily available stationery materials and the utility of these devices to analyze the LAMP results were confirmed through several experiments on a total of 14 field samples. The results showed that the developed LAMP-based detection system was very sensitive and had the advantages of rapid detection and high availability in the field.

Poly-adenine-Coupled LAMP Barcoding to Detect Apple Scar Skin Viroid.

Apple Scar Skin Viroid (ASSVd), a nonprotein coding, circular RNA pathogen is relatively difficult to detect by immunoassay. We report here a one-step reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay to improve selectivity for diagnostic use in detecting ASSVd in plants. ASSVd RT-LAMP was accelerated using loop primers and was found to be highly sensitive with a detection limit of 104 copies of cDNA-ASSVd within 30 min. Real-time LAMP and melting curve analysis could differentiate between the true-positive LAMP amplicons and false-positive nonspecific primer amplification products. The optimized RT-LAMP was then followed by the addition of nonthiolated AuNP:poly-adenine (A10)-ASSVd LAMP barcodes, showing a high authentication capacity with colorimetric changes. This type of barcoding assay is a potential alternative for rapid and multiple viroid diagnosis, providing for visible sensing in the field that can be applied to viroid-free planting.

Three-Dimensional Fin-Structured Semiconducting Carbon Nanotube Network Transistor.

Three-dimensional (3-D) fin-structured carbon nanotube field-effect transistors (CNT-FETs) with purified 99.9% semiconducting CNTs were demonstrated on a large scale 8 in. silicon wafer. The fabricated 3-D CNT-FETs take advantage of the 3-D geometry and exhibit enhanced electrostatic gate controllability and superior charge transport. A trigated structure surrounding the randomly networked single-walled CNT channel was formed on a fin-like 3-D silicon frame, and as a result, the effective packing density increased to almost 600 CNTs/µm. Additionally, highly sensitive controllability of the threshold voltage (VTH) was achieved using a thin back gate oxide in the same silicon frame to control power consumption and enhance performance. Our results are expected to broaden the design margin of CNT-based circuit architectures for versatile applications. The proposed 3-D CNT-FETs can potentially provide a desirable alternative to silicon based nanoelectronics and a blueprint for furthering the practical use of emerging low-dimensional materials other than CNTs.

Electrocautery-Ignited Surgical Field Fire Caused by a High Oxygen Level during Tracheostomy.

Tracheostomy is a relatively common surgical procedure that is performed easily in an operating room or intensive care unit. Open tracheostomy is needed in patients requiring prolonged ventilation when percutaneous tracheostomy is inappropriate. Sometimes, it is difficult to achieve bleeding control in the peritracheal soft tissue, and in such cases, we usually use diathermy. However, the possibility of an electrocautery-ignited surgical field fire can be overlooked during the procedure. This case report serves as a reminder that the risk of a surgical field fire during tracheostomy is real, particularly in patients requiring high-oxygen therapy.

Capsaicin-induced apoptosis of FaDu human pharyngeal squamous carcinoma cells.

PURPOSE: To investigate the anti-tumor effect of capsaicin on human pharyngeal squamous carcinoma cells (FaDu). MATERIALS AND METHODS: The expression of apoptosis/cell cycle-related proteins (or genes) was examined by reverse transcriptase- polymerase chain reaction, western blotting and ELISA methods, while the apoptotic cell population, cell morphology and DNA fragmentation levels were assessed using flow cytometry, fluorescence microscopy and agarose gel electrophoresis. RESULTS: Capsaicin was found to inhibit the growth and proliferation of FaDu cells in a dose- and time-dependent manner. Apoptotic cell death was confirmed by observing increases in nuclear condensation, nuclear DNA fragmentation and sub-G1 DNA content. The observed increase in cytosolic cytochrome c, activation of caspase 3 and PARP (p85) levels following capsaicin treatment indicated that the apoptotic response was mitochondrial pathway-dependent. Gene/protein expression analysis of Bcl-2, Bad and Bax further revealed decreased anti-apoptotic Bcl-2 protein and increased pro-apoptotic Bad/Bax expression. Furthermore, capsaicin suppressed the cell cycle progression at the G1/S phase in FaDu cells by decreasing the expression of the regulators of cyclin B1 and D1, as well as cyclin-dependent protein kinases cdk-1, cdk-2 and cdk-4. CONCLUSION: Our current data show that capsaicin induces apoptosis in FaDu cells and this response is associated with mitochondrial pathways, possibly by mediating cell cycle arrest at G1/S.

Ultrasonic-assisted nanodimensional self-assembly of poly-3-hexylthiophene for organic photovoltaic cells.

We have demonstrated ultrasonic-assisted nanodimensional self-assembly of a conjugated polymer, P3HT, depending on its regioregularity, on solvent polarity, and on light irradiation. The resulting P3HT nanowires were investigated by means of AFM, UV-vis, and XRD and compared with films made by a conventional thermal annealing method. Obtained results indicate that ultrasonic agitation effectively generates P3HT nanowires, exemplifying a quick route to nanoscale morphology control which contributes to better organic photovoltaic cell performance.

Effective variables to control the fill factor of organic photovoltaic cells.

Effective cell design variables having a large impact on the fill factor (FF) of organic photovoltaic cells (OPVCs) were systematically identified using a general device structure of ITO/PEDOT:PSS/P3HT + PCBM/LiF/Al. The results show that the characteristic properties of the organic layer, such as morphology and thickness, the regioregularity of the conjugated polymer, and the two interfaces between the electrodes and the blend layer have a large influence on the FF by affecting the series resistance (R(s)) and the shunt resistance (R(sh)). The systematic investigation described in this contribution provides a comprehensive understanding of the correlation between the device variables and R(s) and R(sh) and a way to control FF, which is critically important to achieving a high-performance OPVC.