Probing Optical Multi-Level Memory Effects in Single Core-Shell Quantum Dots and Application Through 2D-0D Hybrid Inverters.

Challenges in the development of a multi-level memory (MM) device for multinary arithmetic computers have posed an obstacle to low-power, ultra-high-speed operation. For the effective transfer of a huge amount of data between arithmetic and storage devices, optical communication technology represents a compelling solution. Here, by replicating a floating gate architecture with CdSe/ZnS type-I core/shell quantum dots (QDs), a 2D-0D hybrid optical multi-level memory (OMM) device operated is demonstrated by laser pulses. In the device, laser pulses create linear optically trapped currents with MM characteristics, while conversely, voltage pulses reset all the trapped currents at once. Assuming electron transfer via the energy band alignment between MoS2 and CdSe, the study also establishes the mechanism of the OMM effect. Analysis of the designed device led to a new hypothesis that charge transfer is difficult for laterally adjacent QDs facing a double ZnS shell, which is tested by separately stimulating different positions on the 2D-0D hybrid structure with finely focused laser pulses. Results indicate that each laser pulse induced independent MM characteristics in the 2D-0D hybrid architecture. Based on this phenomenon, we propose a MM inverter to produce MM effects, such as programming and erasing, solely through the use of laser pulses. Finally, the feasibility of a fully optically-controlled intelligent system based on the proposed OMM inverters is evaluated through a CIFAR-10 pattern recognition task using a convolutional neural network.

What drives the use of wearable healthcare devices? A cross-country comparison between the US and Korea.

Objective: Given the rapid growth of the wearable healthcare device market, we examined the associations among health-related and technology-related characteristics of using wearable healthcare devices and demonstrated how the associations differ between the US and Korean users. Methods: Online self-administered surveys were conducted with 4098 participants (3035 in the US and 1063 in Korea) who were recruited through two online survey service providers based on quota sampling. The primary outcome was the use of wearable healthcare devices. Seven health-related, two technology-related, and five socio-demographic factors were included as explanatory variables. Binary logistic regression analyses and a Chow test were conducted. Results: The health-related characteristics that were significantly associated with using wearable healthcare devices included disease-related worries (ß = 0.11**), health information seeking (ß = 0.26***), physical activity (ß = 0.62***), and health-related expenditures ($50-$199, ß = 0.38***; $200 or more, ß = 0.56***). Hedonic (ß = 0.33***), social (ß = 0.31***), and cognitive innovativeness (ß = 0.14*) also exhibited positive relationships. Younger, higher earner, and individuals with a child were more likely to use wearable healthcare devices. However, for Korean users, several associations disappeared including health information seeking, hedonic and social innovativeness, age, and household income. Conclusions: Key drivers of using wearable healthcare devices include greater concern about a specific illness, active engagement in health-promoting behaviors, and hedonic and social motivation to adopt new technologies. However, more country-specific considerations are needed in future studies to identify the main benefits for target markets.

Fermi-Level Pinning-Free WSe2 Transistors via 2D Van der Waals Metal Contacts and Their Circuits.

Precise control over the polarity of transistors is a key necessity for the construction of complementary metal-oxide-semiconductor circuits. However, the polarity control of 2D transistors remains a challenge because of the lack of a high-work-function electrode that completely eliminates Fermi-level pinning at metal-semiconductor interfaces. Here, a creation of clean van der Waals contacts is demonstrated, wherein a metallic 2D material, chlorine-doped SnSe2 (Cl-SnSe2 ), is used as the high-work-function contact, providing an interface that is free of defects and Fermi-level pinning. Such clean contacts made from Cl-SnSe2 can pose nearly ideal Schottky barrier heights, following the Schottky-Mott limit and thus permitting polarity-controllable transistors. With the integration of Cl-SnSe2 as contacts, WSe2 transistors exhibit pronounced p-type characteristics, which are distinctly different from those of the devices with evaporated metal contacts, where n-type transport is observed. Finally, this ability to control the polarity enables the fabrication of functional logic gates and circuits, including inverter, NAND, and NOR.

An Asymmetry Field-Effect Phototransistor for Solving Large Exciton Binding Energy of 2D TMDCs.

The probing of fundamental photophysics is a key prerequisite for the construction of diverse optoelectronic devices and circuits. To date, though, photocarrier dynamics in 2D materials remains unclear, plagued primarily by two issues: a large exciton binding energy, and the lack of a suitable system that enables the manipulation of excitons. Here, a WSe2 -based phototransistor with an asymmetric split-gate configuration is demonstrated, which is named the "asymmetry field-effect phototransistor" (AFEPT). This structure allows for the effective modulation of the electric-field profile across the channel, thereby providing a standard device platform for exploring the photocarrier dynamics of the intrinsic WSe2 layer. By controlling the electric field, this work the spatial evolution of the photocurrent is observed, notably with a strong signal over the entire WSe2 channel. Using photocurrent and optical spectroscopy measurements, the physical origin of the novel photocurrent behavior is clarified and a room-temperature exciton binding energy of 210 meV is determined with the device. In the phototransistor geometry, lateral p-n junctions serve as a simultaneous pathway for both photogenerated electrons and holes, reducing their recombination rate and thus enhancing photodetection. The study establishes a new device platform for both fundamental studies and technological applications.

Enpp2 Expression by Dendritic Cells Is a Key Regulator in Migration.

Enpp2 is an enzyme that catalyzes the conversion of lysophosphatidylcholine (LPC) to lysophosphatidic acid (LPA), which exhibits a wide variety of biological functions. Here, we examined the biological effects of Enpp2 on dendritic cells (DCs), which are specialized antigen-presenting cells (APCs) characterized by their ability to migrate into secondary lymphoid organs and activate naïve T-cells. DCs were generated from bone marrow progenitors obtained from C57BL/6 mice. Enpp2 levels in DCs were regulated using small interfering (si)RNA or recombinant Enpp2. Expression of Enpp2 in LPS-stimulated mature (m)DCs was high, however, knocking down Enpp2 inhibited mDC function. In addition, the migratory capacity of mDCs increased after treatment with rmEnpp2; this phenomenon was mediated via the RhoA-mediated signaling pathway. Enpp2-treated mDCs showed a markedly increased capacity to migrate to lymph nodes in vivo. These findings strongly suggest that Enpp2 is necessary for mDC migration capacity, thereby increasing our understanding of DC biology. We postulate that regulating Enpp2 improves DC migration to lymph nodes, thus improving the effectiveness of cancer vaccines based on DC.

Near-Infrared Self-Powered Linearly Polarized Photodetection and Digital Incoherent Holography Using WSe2/ReSe2 van der Waals Heterostructure.

Polarization-sensitive photodetection has attracted considerable attention as an emerging technology for future optoelectronic applications such as three-dimensional (3D) imaging, quantum optics, and encryption. However, traditional photodetectors based on Si or III-V InGaAs semiconductors cannot directly detect polarized light without additional optical components. Herein, we demonstrate a self-powered linear-polarization-sensitive near-infrared (NIR) photodetector using a two-dimensional WSe2/ReSe2 van der Waals heterostructure. The WSe2/ReSe2 heterojunction photodiode with semivertical geometry exhibits excellent performance: an ideality factor of 1.67, a broad spectral photoresponse of 405-980 nm with a significant photovoltaic effect, outstanding linearity with a linear dynamic range wider than 100 dB, and rapid photoswitching behavior with a cutoff frequency up to 100 kHz. Strongly polarized excitonic transitions around the band edge in ReSe2 lead to significant 980 nm NIR linear-polarization-dependent photocurrent. This linear polarization sensitivity remains stable even after exposure to air for longer than five months. Furthermore, by leveraging the NIR (980 nm)-selective linear polarization detection of this photodiode under photovoltaic operation, we demonstrate digital incoherent holographic 3D imaging.

Effect of Intra- and Post-Operative Fluid and Blood Volume on Postoperative Pulmonary Edema in Patients with Intraoperative Massive Bleeding.

In patients with intraoperative massive bleeding, the effects of fluid and blood volume on postoperative pulmonary edema are uncertain. Patients with intraoperative massive bleeding who had undergone a non-cardiac surgery in five hospitals were enrolled in this study. We evaluated the association of postoperative pulmonary edema risk and intra- and post-operatively administered fluid and blood volumes in patients with intraoperative massive bleeding. In total, 2090 patients were included in the postoperative pulmonary edema analysis, and 300 patients developed pulmonary edema within 72 h of the surgery. The postoperative pulmonary edema with hypoxemia analysis included 1660 patients, and the condition occurred in 161 patients. An increase in the amount of red blood cells transfused per hour after surgery increased the risk of pulmonary edema (hazard ratio: 1.03; 95% confidence interval: 1.01-1.05; p = 0.013) and the risk of pulmonary edema with hypoxemia (hazard ratio: 1.04; 95% confidence interval: 1.01-1.07; p = 0.024). An increase in the red blood cells transfused per hour after surgery increased the risk of developing pulmonary edema. This increase can be considered as a risk factor for pulmonary edema.

Frequency Doubler and Universal Logic Gate Based on Two-Dimensional Transition Metal Dichalcogenide Transistors with Low Power Consumption.

Two-dimensional transition metal dichalcogenide semiconductors are very promising candidates for future electronic applications with low power consumption due to a low leakage current and high on-off current ratio. In this study, we suggest a complementary circuit consisting of ambipolar WSe2 and n-MoS2 field-effect transistors (FETs), which demonstrate dual functions of a frequency doubler and single inversion AND (SAND) logic gate. In order to reduce the power consumption, a high-quality thin h-BN single crystal is used as a gate dielectric that leads to a low operating voltage of less than 5 V. By combining the low operating voltage with a low operating current in the complementary circuit, a low power consumption of 300 nW (a minimum of 10 pW) has been achieved, which is a significant improvement compared to the tens of µW consumed by a graphene channel. The complementary circuit shows the effective frequency doubling of the input with a dynamic range from 20 to 100 Hz. Furthermore, this circuit satisfies all the truth tables of a SAND logic gate that can be used as a universal logic gate like NAND. Considering that the NAND logic gate generally consists of four transistors, it is significantly advantageous to implement the equivalent circuit SAND logic gate with only two FETs. Our results open up possibilities for analog- and logic-circuit applications based on low-dimensional semiconductors.

Clean Interface Contact Using a ZnO Interlayer for Low-Contact-Resistance MoS2 Transistors.

Two-dimensional transition metal dichalcogenides (TMDCs) have emerged as promising materials for next-generation electronics due to their excellent semiconducting properties. However, high contact resistance at the metal-TMDC interface plagues the realization of high-performance devices. Here, an effective metal-interlayer-semiconductor (MIS) contact is demonstrated, wherein an ultrathin ZnO interlayer is inserted between the metal electrode and MoS2, providing damage-free and clean interfaces at electrical contacts. Using TEM imaging, we show that the contact interfaces were atomically clean without any apparent damages. Compared to conventional Ti/MoS2 contacts, the MoS2 devices with a Ti/ZnO/MoS2 contact exhibit a very low contact resistance of 0.9 kΩ µm. These improvements are attributed to the following mechanisms: (a) Fermi-level depinning at the metal/MoS2 interface by reducing interface disorder and (b) presence of interface dipole at the metal/ZnO interface, consequently reducing the Schottky barrier and contact resistance. Further, the contact resistivity of a Ti/ZnO/MoS2 contact is insensitive to the variation of ZnO thickness, which facilitates large-scale production. Our work not only elucidates the underlying mechanisms for the operation of the MIS contact but also provides a simple and damage-free strategy for conventional aggressive metal deposition that is potentially useful for the realization of large-scale 2D electronics with low-resistance contacts.

Pdlim4 is essential for CCR7-JNK-mediated dendritic cell migration and F-actin-related dendrite formation.

Dendritic cells (DCs) are the most potent professional antigen (Ag)-presenting cells and inducers of T cell-mediated immunity. A previous microarray analysis identified PDZ and LIM domain protein 4 (Pdlim4) as a candidate marker for DC maturation. The aim of this study was to investigate whether Pdlim4 influences DC migration and maturation. Mouse bone marrow-derived DCs were transduced lentivirally with Pdlim4 short hairpin RNA and examined by confocal microscopy, flow cytometry, ELISA, and Western blotting. Pdlim4 was highly induced in LPS-stimulated mature DCs (mDCs). Pdlim4-knockdown mDCs showed reduced expression of molecules associated with Ag presentation and T-cell costimulation, reduced cytokine production, and functional defects in their ability to activate T cells. Moreover, Pdlim4 was necessary for mDC migration via C-C chemokine receptor type 7 (CCR7)-JNK in in vitro Transwell assays. The importance of Pdlim4 in DC migration was confirmed with an in vivo migration model in which C57BL/6 mice were injected with fluorescently labeled DCs in the footpad and migration to the popliteal lymph nodes was assessed by flow cytometry. Moreover, dendrite formation in mDCs was remarkably attenuated under Pdlim4 knockdown. Taken together, these results demonstrate that Pdlim4 is necessary for DC migration via CCR7-JNK, dendrite formation, and subsequent development of functional T-cell responses.-Yoo, J.-Y., Jung, N.-C., Lee, J.-H., Choi, S.-Y., Choi, H.-J., Park, S.-Y., Jang, J.-S., Byun, S.-H., Hwang, S.-U., Noh, K.-E., Park, Y., Lee, J., Song, J.-Y., Seo, H. G., Lee, H. S., Lim, D.-S. Pdlim4 is essential for CCR7-JNK-mediated dendritic cell migration and F-actin-related dendrite formation.

Rsad2 is necessary for mouse dendritic cell maturation via the IRF7-mediated signaling pathway.

Dendritic cells (DCs) are the most potent professional antigen presenting cells and inducers of T cell-mediated immunity. However, few specific markers of mature DCs (mDC) have been reported. A previous microarray analysis revealed expression of mDC-specific genes and identified Rsad2 (radical S-adenosyl methionine domain containing 2) as a candidate specific marker for DC maturation. Mouse bone marrow-derived DCs were transfected with Rsad2 siRNA and examined by flow cytometry, ELISA, western, and confocal microscopy. C57BL/6 mice received intravenously B16F10 cells to establish a pulmonary metastasis model. Tumor-bearing mice then received subcutaneously two injections of mDCs or Rsad2 knockdown DCs. The cytotoxic T lymphocyte (CTL) population was examined from splenocytes of DC-vaccinated mice by flow cytometry. Rsad2 was induced at high levels in LPS-stimulated mDCs and mDC function was markedly attenuated under conditions of Rsad2 knockdown. Moreover, Rsad2 was necessary for mDC maturation via the IRF7-mediated signaling pathway. The importance of Rsad2 was confirmed in an Rsad2 knockdown lung metastasis mouse model in which mDCs lost their antitumor efficacy. Data on the CTL population further supported the results as above. Taken together, Rsad2 was an obvious and specific marker necessary for DC maturation and these findings will be clearly helpful for further understanding of DC biology.

Low-temperature-grown continuous graphene films from benzene by chemical vapor deposition at ambient pressure.

There is significant interest in synthesizing large-area graphene films at low temperatures by chemical vapor deposition (CVD) for nanoelectronic and flexible device applications. However, to date, low-temperature CVD methods have suffered from lower surface coverage because micro-sized graphene flakes are produced. Here, we demonstrate a modified CVD technique for the production of large-area, continuous monolayer graphene films from benzene on Cu at 100-300 °C at ambient pressure. In this method, we extended the graphene growth step in the absence of residual oxidizing species by introducing pumping and purging cycles prior to growth. This led to continuous monolayer graphene films with full surface coverage and excellent quality, which were comparable to those achieved with high-temperature CVD; for example, the surface coverage, transmittance, and carrier mobilities of the graphene grown at 300 °C were 100%, 97.6%, and 1,900-2,500 cm(2) V(-1) s(-1), respectively. In addition, the growth temperature was substantially reduced to as low as 100 °C, which is the lowest temperature reported to date for pristine graphene produced by CVD. Our modified CVD method is expected to allow the direct growth of graphene in device manufacturing processes for practical applications while keeping underlying devices intact.

Isoindigo-Based Donor-Acceptor Conjugated Polymers for Air-Stable Nonvolatile Memory Devices.

Nonvolatile resistive memory devices based on a new low bandgap donor-acceptor (D-A) conjugated polymer, poly((E)-6,6'-bis(2,3-dihydrothieno[3,4-b][1,4]dioxine-5-yl)-1,1'-bis(2-octyldodecyl)-[3,3'-biindolinyi-dene]-2,2'-dione) (PIDED), which are fabricated and operated in ambient air, are reported. The D-A conjugated polymer is synthesized from 2,3-dihydrothieno[3,4-b][1,4]dioxine and isoindigo as an electron donor and an electron acceptor, respectively, using CH-arylation polymerization. The devices show nonvolatile, unipolar resistive switching behaviors with a high on/off current ratio (∼104), excellent endurance cycles (>200 cycles), and a long retention time (>104 s) in ambient air. These properties remain stable in ambient air over one year, demonstrating that the device performance is significantly unaffected by exposure to air as the isoindigo has strong electron-withdrawing character and the PIDED exhibits a high degree of crystallinity. This study may pave the way for use of practical nonvolatile organic memory devices operating in ambient air.

Percutaneous aspiration of lumbar zygapophyseal joint synovial cyst under fluoroscopic guidance -A case report-.

A 51-year-old man with a 1-month history of lower back pain and radiating pain visited to our pain clinic. A magnetic resonance imaging (MRI) scan demonstrated a cyst like mass at the level of the L4-5 interspace and compression of the thecal sac and the nerve root on the right side. We performed percutaneous needle aspiration of the lumbar zygapophyseal joint synovial cyst under fluoroscopic guidance. The patient felt an immediate relief of symptoms after the aspiration, and had no signs or symptoms of recurrence at the follow-up 6 months later. No demonstrable lesion was found in the 6 months follow-up MRI.