Eliminating Ferroelectric Hysteresis in All-Two-Dimensional Gate-Stack Negative-Capacitance Transistors.

Boltzmann distribution thermal tails of carriers restrain the subthreshold swing (SS) of field-effect transistors (FETs) to be lower than 60 mV/decade at room temperature, which restrains the reduction of operate-voltage and power consumption of transistors. The negative-capacitance FET (NC FET) is expected to break through this physical limit and obtain a steep SS by amplifying the gate voltage through the negative capacitance effect of the ferroelectric thin film, providing a new way to further reduce the power consumption of the transistor at the end of Moore's law. Here, we show a MoS2 NC FET with a CuInP2S6 ferroelectric, exhibiting a large on/off ratio of 108, a steep SS as low as 6 mV/decade, and a wide sub-60 mV/decade drain current range of more than 4 orders of magnitude while sacrificially inducing a huge hysteresis larger than 500 mV. Furthermore, we found that by inserting the h-phase boron nitride (h-BN) layer with suitable thickness, the dielectric capacitance matches the ferroelectric negative capacitance better, and thus the hysteresis on the transfer curve is reduced, and the ideal switching-behavior transistors with SS as low as 62 mV/decade and only 5 mV negligible hysteresis were obtained. Our work demonstrates that under the capacitance-matching condition, the hysteresis-free negative-capacitance transistors do not act as the predicted steep-slope transistors, but their voltage-saving still occurs instead as a type of effective transconductance booster with more than 20 times transconductance amplification.

Sorting of Cluster-Confined Metallic Single-Walled Carbon Nanotubes for Fabricating Atomically Vacant Uranium Oxide.

Single-walled carbon nanotube (SWCNT) heterostructures have shown great potential in catalysis, magnetism, and nanofluidics, in which host SWCNTs with certain conductivity (metallic or semiconducting) are highly required. Herein, inspired by the large molecular weight and redox properties of polyoxometalate (POM) clusters, we reported the selective separation of POM encapsulated metallic SWCNTs (POM@m-SWCNTs) with a uniform diameter through density gradient ultracentrifugation (DGU). The confined POMs increased the SWCNT density and amplified the nanotubes' density difference, thus greatly lowering the centrifugal force (70,000g) of DGU. With this strategy, a series of POM@m-SWCNTs of ∼1.2 nm with high purity were sorted. The mechanism supported by theoretical and experimental evidence showed that the separation of m-SWCNTs depended on not only nanotube/cluster size but also the conductivity of SWCNTs. The smallest 1.2 nm m-SWCNT that can exactly accommodate a 0.9 nm-{Mo6} cluster exhibited the maximum electron transfer to inner clusters; thus, intertube π-π stacking of such m-SWCNTs was greatly loosened, leading to the preferential dispersion into individual ones and partitioning in the uppermost layer after DGU. As a proof-of-concept application, this sorting strategy was extended to separate heavy-element 238U-encapsulated m-SWCNTs. The phase-pure, tiny (1-2.5 nm) U4O9 crystals with atomic vacancy clusters were fabricated on m-SWCNTs through growth kinetic control. This work may provide a general way to construct desired actinide materials on specific SWCNTs.

Lactiplantibacillus plantarum NKK20 Alleviates High-Fat-Diet-Induced Nonalcoholic Fatty Liver Disease in Mice through Regulating Bile Acid Anabolism.

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic disease in modern society. It is characterized by an accumulation of lipids in the liver and an excessive inflammatory response. Clinical trials have provided evidence that probiotics may prevent the onset and relapse of NAFLD. The aim of this study was to explore the effect of Lactiplantibacillus plantarum NKK20 strain (NKK20) on high-fat-diet-induced NAFLD in an ICR murine model and propose the underlying mechanism whereby NKK20 protects against NAFLD. The results showed that the administration of NKK20 ameliorated hepatocyte fatty degeneration, reduced total cholesterol and triglyceride concentrations, and alleviated inflammatory reactions in NAFLD mice. In addition, the 16S rRNA sequencing results indicated that NKK20 could decrease the abundance of Pseudomonas and Turicibacter and increase the abundance of Akkermansia in NAFLD mice. LC-MS/MS analysis showed that NKK20 could significantly increase the concentration of short-chain fatty acids (SCFAs) in the colon contents of mice. The obtained non-targeted metabolomics results revealed a significant difference between the metabolites in the colon contents of the NKK20 administration group and those in the high-fat diet group, in which a total of 11 different metabolites that were significantly affected by NKK20 were observed, and these metabolites were mainly involved in bile acid anabolism. UPLC-MS technical analysis revealed that NKK20 could change the concentrations of six conjugated and free bile acids in mouse liver. After being treated with NKK20, the concentrations of cholic acid, glycinocholic acid, and glycinodeoxycholic acid in livers of the NAFLD mice were significantly decreased, while the concentration of aminodeoxycholic acid was significantly increased. Thus, our findings indicate that NKK20 can regulate bile acid anabolism and promote the production of SCFA, which can inhibit inflammation and liver damage and thus prevent the development of NAFLD.

Ballistic two-dimensional InSe transistors.

The International Roadmap for Devices and Systems (IRDS) forecasts that, for silicon-based metal-oxide-semiconductor (MOS) field-effect transistors (FETs), the scaling of the gate length will stop at 12 nm and the ultimate supply voltage will not decrease to less than 0.6 V (ref. 1). This defines the final integration density and power consumption at the end of the scaling process for silicon-based chips. In recent years, two-dimensional (2D) layered semiconductors with atom-scale thicknesses have been explored as potential channel materials to support further miniaturization and integrated electronics. However, so far, no 2D semiconductor-based FETs have exhibited performances that can surpass state-of-the-art silicon FETs. Here we report a FET with 2D indium selenide (InSe) with high thermal velocity as channel material that operates at 0.5 V and achieves record high transconductance of 6 mS µm-1 and a room-temperature ballistic ratio in the saturation region of 83%, surpassing those of any reported silicon FETs. An yttrium-doping-induced phase-transition method is developed for making ohmic contacts with InSe and the InSe FET is scaled down to 10 nm in channel length. Our InSe FETs can effectively suppress short-channel effects with a low subthreshold swing (SS) of 75 mV per decade and drain-induced barrier lowering (DIBL) of 22 mV V-1. Furthermore, low contact resistance of 62 Ω µm is reliably extracted in 10-nm ballistic InSe FETs, leading to a smaller intrinsic delay and much lower energy-delay product (EDP) than the predicted silicon limit.

Short-Chain Fatty Acids Weaken Ox-LDL-Induced Cell Inflammatory Injury by Inhibiting the NLRP3/Caspase-1 Pathway and Affecting Cellular Metabolism in THP-1 Cells.

Short-chain fatty acids (SCFAs) are important anti-inflammatory metabolites of intestinal flora. Oxidized low-density lipoprotein (ox-LDL)-induced macrophage activation is critical for the formation of atherosclerosis plaque. However, the association between SCFAs and ox-LDL-induced macrophage activation with respect to the formation of atherosclerosis plaque has not yet been elucidated. The present study investigated whether SCFAs (sodium acetate, sodium propionate, and sodium butyrate) can affect ox-LDL-induced macrophage activation and potential signaling pathways via regulation of the expression of the NLRP3/Caspase-1 pathway. Using human monocyte-macrophage (THP-1) cells as a model system, it was observed that ox-LDL not only induced cell inflammatory injury but also activated the NLRP3/Caspase-1 pathway. The exogenous supplementation of three SCFAs could significantly inhibit cell inflammatory injury induced by ox-LDL. Moreover, three SCFAs decreased the expression of IL-1ß and TNF-α via the inactivation of the NLRP3/Caspase-1 pathway induced by ox-LDL. Furthermore, three SCFAs affected cellular metabolism in ox-LDL-induced macrophages, as detected by untargeted metabolomics analysis. The results of the present study indicated that three SCFAs inhibited ox-LDL-induced cell inflammatory injury by blocking the NLRP3/Caspase-1 pathway, thereby improving cellular metabolism. These findings may provide novel insights into the role of SCFA intervention in the progression of atherosclerotic plaque formation.

Strain-Free Layered Semiconductors for 2D Transistors with On-State Current Density Exceeding 1.3 mA µm-1.

High-mobility and air-stable two-dimensional (2D) Bi2O2Se semiconductor holds promise as an alternative fast channel material for next-generation transistors. However, one of the key challenges remaining in 2D Bi2O2Se is to prepare high-quality crystals to fabricate the high-performance transistors with a high on-state current density. Here, we present the free-standing growth of strain-free 2D Bi2O2Se crystals. An ultrahigh Hall mobility of 160 000 cm2 V-1 s-1 is measured in strain-free Bi2O2Se crystals at 2 K, which enables the observation of Shubnikov-de Haas quantum oscillations and shows substantially higher (>4 times) mobility over previous in-plane 2D crystals. The fabricated 2D transistors feature an on-off current ratio of ∼106 and a record-high on-state current density of ∼1.33 mA µm-1, which is comparable to that of commercial Si and Ge n-type field-effect transistors (FETs) for similar channel length. Strain-free 2D Bi2O2Se provides a promising material platform for studying novel quantum phenomena and exploration of high-performance low-power electronics.

Soft-lock drawing of super-aligned carbon nanotube bundles for nanometre electrical contacts.

The assembly of single-walled carbon nanotubes (CNTs) into high-density horizontal arrays is strongly desired for practical applications, but challenges remain despite myriads of research efforts. Herein, we developed a non-destructive soft-lock drawing method to achieve ultraclean single-walled CNT arrays with a very high degree of alignment (angle standard deviation of ~0.03°). These arrays contained a large portion of nanometre-sized CNT bundles, yielding a high packing density (~400 µm-1) and high current carrying capacity (∼1.8 × 108 A cm-2). This alignment strategy can be generally extended to diverse substrates or sources of raw single-walled CNTs. Significantly, the assembled CNT bundles were used as nanometre electrical contacts of high-density monolayer molybdenum disulfide (MoS2) transistors, exhibiting high current density (~38 µA µm-1), low contact resistance (~1.6 kΩ µm), excellent device-to-device uniformity and highly reduced device areas (0.06 µm2 per device), demonstrating their potential for future electronic devices and advanced integration technologies.

Unexpected phosphorous removal in a Candidatus_Competibacter and Defluviicoccus dominated reactor.

Competition between polyphosphate- and glycogen-accumulating organisms (PAOs and GAOs) is problematic in the enhanced biological phosphorus removal (EBPR) process. Aiming at a high phosphorus removal efficiency (PRE), the phosphorus release amount (PRA) is considered an essential evaluating indicator. However, the correlations between PRE and PRA and the abundance of PAOs are not clear. In this study, the EBPR was established and optimized via adjusting influent carbon to phosphorus ratio (C/P). After 110-day operation, 17.67 mg/L of PRA and 75.86% of PRE simultaneously achieved with influent C/P of 40 mgCOD/mgP. As for PAOs, Candidatus_Accumulibacter and Tetrasphaera were absent, while Hypomicrobium (3.69%), Pseudofulvimonas (1.02%), and unclassified_f_Rhodobacteraceae (2.41%) were found at a low level. On the contrary, Candidatus_Competibacter and Defluviicoccus were unexpectedly enriched with high abundance (24.94% and 16.04%, respectively). These results also suggested that it was difficult to distinguish whether PAOs were enriched merely based on the variations of PRA and PRE.

Screwdriver aspiration during implant surgery: case report and literature review / 口腔疾病防治

Objective @#To discuss and summarize the preventive measures and treatment methods for aspiration/ingestion during dental procedures.@*Methods @# One case of aspiration during an implant operation was reported, and the literature on aspiration/ingestion during oral procedures was reviewed.@*Results@#An implant screwdriver accidentally slipped into the mouth of the patient during implant surgery. The patient experienced no obvious discomfort except a few coughs. The surgeon and assistant paused the procedure immediately to search for the screwdriver, but it was not found. The patient declared that there was no special abnormality, such as breathing disorder or chest distress, so we considered that the foreign body was ingestion. After the implant surgery was completed, no foreign body was found in the stomach via gastroscopy. Chest X-ray and CT showed a dense metal shadow in the lower lobe of the left lung. Under local anesthesia, bronchoscopy and biopsy forceps were used by respiratory physicians to clip out the foreign body. After removal of the foreign body, the patient had no obvious discomfort but a slight cough. Cephalexin and metronidazole were given for three days to prevent infection. Three days later, the patient had no complaints of respiratory discomfort. After reviewing the literature, we found that the operation should be paused immediately after aspiration/ingestion occurs during dental procedures and that the dental chair should be laid down to prevent the foreign body from descending deeper, which may increase the difficulty of removal and cause gastrointestinal and respiratory tract injury. The position of the foreign body should be determined by imaging examination, and the corresponding means to remove the foreign body should be performed.@*Conclusion @# Patients may have no obvious symptoms after aspiration/ingestion during dental procedures, and the foreign body can be removed after imaging examination.

Field-effect at electrical contacts to two-dimensional materials.

The inferior electrical contact to two-dimensional (2D) materials is a critical challenge for their application in post-silicon very large-scale integrated circuits. Electrical contacts were generally related to their resistive effect, quantified as contact resistance. With a systematic investigation, this work demonstrates a capacitive metal-insulator-semiconductor (MIS) field-effect at the electrical contacts to 2D materials: The field-effect depletes or accumulates charge carriers, redistributes the voltage potential, and gives rise to abnormal current saturation and nonlinearity. On one hand, the current saturation hinders the devices' driving ability, which can be eliminated with carefully engineered contact configurations. On the other hand, by introducing the nonlinearity to monolithic analog artificial neural network circuits, the circuits' perception ability can be significantly enhanced, as evidenced using a coronavirus disease 2019 (COVID-19) critical illness prediction model. This work provides a comprehension of the field-effect at the electrical contacts to 2D materials, which is fundamental to the design, simulation, and fabrication of electronics based on 2D materials. ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material (results of the simulation and SEM) is available in the online version of this article at 10.1007/s12274-021-3670-y.

Can Carbon Nanotube Transistors Be Scaled Down to the Sub-5 nm Gate Length?

Single-walled carbon nanotubes (CNTs) have been considered as a promising semiconductor to construct transistors and integrated circuits in the future owing to their ultrathin channel thickness and ultrahigh injection velocity. Although a 5 nm gate-length CNT field-effect transistor (FET) has already been experimentally fabricated and demonstrates excellent device performance, the potential or constraint factors on performance have not been explored or revealed. Based on the benchmark of the device performance between the experimental and simulated 5 nm gate-length CNT FETs, we use the first-principles quantum transport approach to explore the performance limit of CNT FETs based on the gate-all-around (GAA) device geometry for the first time. It is found that the GAA CNT FETs can fulfill the ITRS 2028 high-performance target in the 2 nm gate-length node in terms of the on-state current, delay time, and power consumption. We also find that the energy-delay product of the CNT FETs is superior to those of the high-performance 2D materials and Si Fin FETs at the sub-5 nm gate length due to its unique electrical property. Though theoretically the gate length of CNT FETs can be potentially scaled to 2 nm, considering the tradeoff between the performance and power consumption, 5 nm is the ultimate scaled limit.

Host-Guest Molecular Interaction Enabled Separation of Large-Diameter Semiconducting Single-Walled Carbon Nanotubes.

Semiconducting single-walled carbon nanotubes (s-SWCNTs) with a diameter of around 1.0-1.5 nm, which present bandgaps comparable to silicon, are highly desired for electronic applications. Therefore, the preparation of s-SWCNTs of such diameters has been attracting great attention. The inner surface of SWCNTs has a suitable curvature and large contacting area, which is attractive in host-guest chemistry triggered by electron transfer. Here we reported a strategy of host-guest molecular interaction between SWCNTs and inner clusters with designed size, thus selectively separating s-SWCNTs of expected diameters. When polyoxometalate clusters of ∼1 nm in size were filled in the inner cavities of SWCNTs, s-SWCNTs with diameters concentrated at ∼1.3-1.4 nm were selectively extracted with the purity of ∼98% by a commercially available polyfluorene derivative. The field-effect transistors built from the sorted s-SWCNTs showed a typical behavior of semiconductors. The sorting mechanisms associated with size-dependent electron transfer from nanotubes to inner polyoxometalate were revealed by the spectroscopic and in situ electron microscopic evidence as well as the theoretical calculation. The polyoxometalates with designable size and redox property enable the flexible regulation of interaction between the nanotubes and the clusters, thus tuning the diameter of sorted s-SWCNTs. The present sorting strategy is simple and should be generally feasible in other SWCNT sorting techniques, bringing both great easiness in dispersant design and improved selectivity.

Carbon Nanotube Complementary Gigahertz Integrated Circuits and Their Applications on Wireless Sensor Interface Systems.

Along with ultralow-energy delay products and symmetric complementary polarities, carbon nanotube field-effect transistors (CNT FETs) are expected to be promising building blocks for energy-efficient computing technology. However, the work frequencies of the existing CNT-based complementary metal-oxide-semiconductor (CMOS) integrated circuits (ICs) are far below the requirement (850 MHz) in state-of-art wireless communication applications. In this work, we fabricated deep submicron CMOS FETs with considerably improved performance of n-type CNT FETs and hence significantly promoted the work frequency of CNT CMOS ICs to 1.98 GHz. Based on these high-speed and sensitive voltage-controlled oscillators, we then presented a wireless sensor interface circuit with working frequency up to 1.5 GHz spectrum. As a preliminary demonstration, an energy-efficient wireless temperature sensing interface system was realized combining a 150 mAh flexible Li-ion battery and a flexible antenna (center frequency of 915 MHz). In general, the CMOS-logic high-speed CNT ICs showed outstanding energy efficiency and thus may potentially advance the application of CNT-based electronics.

Low Residual Carrier Concentration and High Mobility in 2D Semiconducting Bi2O2Se.

The air-stable and high-mobility two-dimensional (2D) Bi2O2Se semiconductor has emerged as a promising alternative that is complementary to graphene, MoS2, and black phosphorus for next-generation digital applications. However, the room-temperature residual charge carrier concentration of 2D Bi2O2Se nanoplates synthesized so far is as high as about 1019-1020 cm-3, which results in a poor electrostatic gate control and unsuitable threshold voltage, detrimental to the fabrication of high-performance low-power devices. Here, we first present a facile approach for synthesizing 2D Bi2O2Se single crystals with ultralow carrier concentration of ∼1016 cm-3 and high Hall mobility up to 410 cm2 V-1 s-1 simultaneously at room temperature. With optimized conditions, these high-mobility and low-carrier-concentration 2D Bi2O2Se nanoplates with domain sizes greater than 250 µm and thicknesses down to 4 layers (∼2.5 nm) were readily grown by using Se and Bi2O3 powders as coevaporation sources in a dual heating zone chemical vapor deposition (CVD) system. High-quality 2D Bi2O2Se crystals were fabricated into high-performance and low-power transistors, showing excellent current modulation of >106, robust current saturation, and low threshold voltage of -0.4 V. All these features suggest 2D Bi2O2Se as an alternative option for high-performance low-power digital applications.

Dirac-source field-effect transistors as energy-efficient, high-performance electronic switches.

An efficient way to reduce the power consumption of electronic devices is to lower the supply voltage, but this voltage is restricted by the thermionic limit of subthreshold swing (SS), 60 millivolts per decade, in field-effect transistors (FETs). We show that a graphene Dirac source (DS) with a much narrower electron density distribution around the Fermi level than that of conventional FETs can lower SS. A DS-FET with a carbon nanotube channel provided an average SS of 40 millivolts per decade over four decades of current at room temperature and high device current I60 of up to 40 microamperes per micrometer at 60 millivolts per decade. When compared with state-of-the-art silicon 14-nanometer node FETs, a similar on-state current Ion is realized but at a much lower supply voltage of 0.5 volts (versus 0.7 volts for silicon) and a much steeper SS below 35 millivolts per decade in the off-state.

Atomic-Layer-Deposition Growth of an Ultrathin HfO2 Film on Graphene.

Direct growth of an ultrathin gate dielectric layer with high uniformity and high quality on graphene remains a challenge for developing graphene-based transistors due to the chemically inert surface properties of graphene. Here, we develop a method to realize atomic-layer-deposition (ALD) growth of an ultrathin high-κ dielectric layer on graphene through premodifying the graphene surface using electron beam irradiation. An amorphous carbon layer induced by electron beam scanning is formed on graphene and then acts as seeds for ALD growth of high-κ dielectrics. A uniform HfO2 layer with an equivalent oxide thickness of 1.3 nm was grown as a gate dielectric for top-gate graphene field-effect transistors (FETs). The achieved gate capacitance is up to 2.63 µF/cm2, which is the highest gate capacitance on a graphene solid-state device to date. In addition, the fabricated top-gate graphene FETs present a high carrier mobility of up to 2500 cm2/(V·s) and a negligible gate leakage current of down to 0.1 mA/cm2, showing that the ALD-grown HfO2 dielectric layer is highly uniform and of very high quality.

Scaling down contact length in complementary carbon nanotube field-effect transistors.

We performed an experimental investigation on contact length (Lc) scaling of carbon nanotube (CNT) complementary field-effect transistors (FETs). Contact resistances of Sc-contacted (for n-type) and Pd-contacted (for p-type) CNT FETs are respectively retrieved based on the experimental data through the transfer length method (TLM). The performance of Lc scaling of Sc/CNT is proved to be comparable to that of the Pd/CNT contact with Lc larger than approximately 40 nm, but it degrades sharply when further scaling down Lc mainly owing to the surface oxidation of the Sc film. After decoupling the effect of oxide thickness, the intrinsic contact scaling behavior of Sc-contacted CNT FETs is found to be as good as that of the Pd-contacted ones, which can further satisfy the requirement of developing complementary CNT FET technology scaled down to the 14 nm node.

Scaling carbon nanotube complementary transistors to 5-nm gate lengths.

High-performance top-gated carbon nanotube field-effect transistors (CNT FETs) with a gate length of 5 nanometers can be fabricated that perform better than silicon complementary metal-oxide semiconductor (CMOS) FETs at the same scale. A scaling trend study revealed that the scaled CNT-based devices, which use graphene contacts, can operate much faster and at much lower supply voltage (0.4 versus 0.7 volts) and with much smaller subthreshold slope (typically 73 millivolts per decade). The 5-nanometer CNT FETs approached the quantum limit of FETs by using only one electron per switching operation. In addition, the contact length of the CNT CMOS devices was also scaled down to 25 nanometers, and a CMOS inverter with a total pitch size of 240 nanometers was also demonstrated.

[The number of myeloid suppressor cells, Th17 cells of peripheral blood and the serum IL-17 level increase in patients with oral squamous cell carcinoma].

Objective To explore the relationships in the numbers of peripheral blood myeloid derived suppressor cells (MDSCs), Th17 cells, and the IL-17 expression in oral squamous cell carcinoma (OSCC) patients. Methods The fasting venous blood specimens of 34 OSCC patients and 16 heacthy donors were collected, OSCC patients includied 18 cases of stage I and stage II and 16 cases of stage III and stage IV. The percentages of MDSCs and Th17 cells were determined by flow cytometry and the serum level of IL-17 was detected by ELISA. Results The percentages of MDSCs and Th17 cells, and the level of IL-17 in OSCC patients were higher than those in healthy donors. In OSCC patients, the percentages of MDSCs and Th17, and the level of IL-17 were higher in stage III and stage IV than in stage I and II. The significant correlation was found between the number of MDSCs and the level of IL-17, while no correlation was found between the numbers of MDSCs and Th17 cells. Conclusion In OSCC patients, the numbers of MDSCs and Th17 cells, and the level of IL-17 increase compared with healthy donors. There is an interaction between DMSCs and Th17 cells. The IL-17 might originate from other innate immunocytes rather than Th17 cells.