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Of the 98 floating knee injuries that were consecutively treated from 1987 to 1997, 89 patients were available for analysis. There were 80 males and 9 females, ranging from 15 to 70 years old. Average follow-up was 5 (2-12) years. Injury severity scores ranged from 18 to 45. 21 fractures were intra-articular. 55 fractures were open. Substantial comminuted and segmental fractures occurred in 57 cases and 35 cases, respectively. Multivariate analysis showed that increasing age was associated with delays in bony union and full weight bearing ability. An increase in the number of pack years smoked at the time of injury predicted the likelihood of knee stiffness, delays in bony union and full weight bearing ability. Higher injury severity scores were associated with delayed full weight bearing ability. The presence of open fractures predicted the likelihood of knee stiffness and delayed full weight bearing ability. Comminuted fractures were associated with malunion, and segmental fractures with delayed bony union. Using the outcome of floating knee injuries as fair or poor, according to Karlström and Olerud's criteria, we constructed a preoperative prognostic scoring scale which showed a sensitivity of 0.72 and a specificity of 0.90. [ABSTRACT FROM AUTHOR]

Objectives: (1) To determine the pattern of ambulance arrivals in the emergency department (ED) and (2) to review resource allocation based on these data.Methods: All (13 697) ambulance arrivals in 1996 to the ED of Tan Tock Seng Hospital were studied and where relevant compared with the walk in and total arrivals of the same year. The following data were obtained from computer records: (a) patients' demographic data; (b) number of ambulance arrivals by hour; (c) the classification of the ambulance arrivals by emergency or non-emergency, trauma or non-trauma; (d) cause of injury for trauma cases; (e) discharge status.Results: The ambulance arrivals in 1996 constituted 12.4% of the patient load for this department. There was no difference in modes of patient arrival to the ED by sex and ethnic group. However, there was significant evidence to show that more patients age > 60 came by ambulance than those age < 12 (p << 0.01). Some 98.5% of the ambulance arrivals were emergencies; 40.7% of the ambulance arrivals were attributable to trauma versus 27.3% of the walk in arrivals. The majority of the trauma cases brought in by ambulance were because of road traffic accidents (15.3%) or home accidents (7.4%). The peak in ambulance arrivals was between 2100-2300 hours compared with 1000-1200 for the walk in arrivals. More than half of the ambulance arrivals were admitted.Conclusion: In planning resource allocation and in the development of contingency plans, the resource use of ambulance patients and the pattern of their arrivals should be taken into account. [ABSTRACT FROM AUTHOR]

Hafnia-based ferroelectric (FE) thin films are promising candidates for semiconductor memories. However, a fundamental challenge that persists is the lack of understanding regarding dimensional scaling, including thickness scaling and area scaling, of the functional properties and their heterogeneity in these films. In this work, excellent ferroelectricity and switching endurance are demonstrated in 4 nm-thick Hf 0.5 Zr 0.5 O 2 (HZO) capacitors with molybdenum electrodes in capacitors as small as 65 nm × 45 nm in size. The HZO layer in these capacitors can be crystallized into the ferroelectric orthorhombic phase at the low temperature of 400 °C, making them compatible for back-end-of-line (BEOL) FE memories. With the benefits of thickness scaling, low operation voltage (1.2 V) is achieved with high endurance (>10 10 cycles); however, a significant fatigue regime is noted. We observed that the bottom electrode, rather than the top electrode, plays a dominant role in the thickness scaling of HZO ferroelectric behavior. Furthermore, ultrahigh switched polarization (remanent polarization 2 P r ∼ 108 μC cm -2 ) is observed in some nanoscale devices. This study advances the understanding of dimensional scaling effects in HZO capacitors for high-performance FE memories.

Data-centric applications are pushing the limits of energy-efficiency in today's computing systems, including those based on phase-change memory (PCM). This technology must achieve low-power and stable operation at nanoscale dimensions to succeed in high-density memory arrays. Here we use a novel combination of phase-change material superlattices and nanocomposites (based on Ge 4 Sb 6 Te 7 ), to achieve record-low power density ≈ 5 MW/cm 2 and ≈ 0.7 V switching voltage (compatible with modern logic processors) in PCM devices with the smallest dimensions to date (≈ 40 nm) for a superlattice technology on a CMOS-compatible substrate. These devices also simultaneously exhibit low resistance drift with 8 resistance states, good endurance (≈ 2 × 10 8 cycles), and fast switching (≈ 40 ns). The efficient switching is enabled by strong heat confinement within the superlattice materials and the nanoscale device dimensions. The microstructural properties of the Ge 4 Sb 6 Te 7 nanocomposite and its high crystallization temperature ensure the fast-switching speed and stability in our superlattice PCM devices. These results re-establish PCM technology as one of the frontrunners for energy-efficient data storage and computing., (© 2024. The Author(s).)

Carbon nanotube (CNT) transistors demonstrate high mobility but also experience off-state leakage due to the small effective mass and band gap. The lower limit of off-current ( I MIN ) was measured in electrostatically doped CNT metal-oxide-semiconductor field-effect transistors (MOSFETs) across a range of band gaps (0.37 to 1.19 eV), supply voltages (0.5 to 0.7 V), and extension doping levels (0.2 to 0.8 carriers/nm). A nonequilibrium Green's function (NEGF) model confirms the dependence of I MIN on CNT band gap, supply voltage, and extension doping level. A leakage current design space across CNT band gap, supply voltage, and extension doping is projected based on the validated NEGF model for long-channel CNT MOSFETs to identify the appropriate device design choices. The optimal extension doping and CNT band gap design choice for a target off-current density are identified by including on-current projection in the leakage current design space. An extension doping level >0.5 carrier/nm is required for optimized on-current.

Resistive random-access memory (RRAM) is a promising technology for data storage and neuromorphic computing; however, cycle-to-cycle and device-to-device variability limits its widespread adoption and high-volume manufacturability. Improving the structural accuracy of RRAM devices during fabrication can reduce these variabilities by minimizing the filamentary randomness within a device. Here, we studied area-selective atomic layer deposition (AS-ALD) of the HfO 2 dielectric for the fabrication of RRAM devices with higher reliability and accuracy. Without requiring photolithography, first we demonstrated ALD of HfO 2 patterns uniformly and selectively on Pt bottom electrodes for RRAM but not on the underlying SiO 2 /Si substrate. RRAM devices fabricated using AS-ALD showed significantly narrower operating voltage range (2.6 × improvement) and resistance states than control devices without AS-ALD, improving the overall reliability of RRAM. Irrespective of device size (1 × 1, 2 × 2, and 5 × 5 μm 2 ), we observed similar improvement, which is an inherent outcome of the AS-ALD technique. Our demonstration of AS-ALD for improved RRAM devices could further encourage the adoption of such techniques for other data storage technologies, including phase-change, magnetic, and ferroelectric RAM.

Memristive technology has been rapidly emerging as a potential alternative to traditional CMOS technology, which is facing fundamental limitations in its development. Since oxide-based resistive switches were demonstrated as memristors in 2008, memristive devices have garnered significant attention due to their biomimetic memory properties, which promise to significantly improve power consumption in computing applications. Here, we provide a comprehensive overview of recent advances in memristive technology, including memristive devices, theory, algorithms, architectures, and systems. In addition, we discuss research directions for various applications of memristive technology including hardware accelerators for artificial intelligence, in-sensor computing, and probabilistic computing. Finally, we provide a forward-looking perspective on the future of memristive technology, outlining the challenges and opportunities for further research and innovation in this field. By providing an up-to-date overview of the state-of-the-art in memristive technology, this review aims to inform and inspire further research in this field.

Phase-change superlattices with nanometer thin sublayers are promising for low-power phase-change memory (PCM) on rigid and flexible platforms. However, the thermodynamics of the phase transition in such nanoscale superlattices remain unexplored, especially at ultrafast scanning rates, which is crucial for our fundamental understanding of superlattice-based PCM. Here, we probe the phase transition of Sb 2 Te 3 (ST)/Ge 2 Sb 2 Te 5 (GST) superlattices using nanocalorimetry with a monolayer sensitivity (∼1 Å) and a fast scanning rate (10 5 K/s). For a 2/1.8 nm/nm Sb 2 Te 3 /GST superlattice, we observe an endothermic melting transition with an ∼240 °C decrease in temperature and an ∼8-fold decrease in enthalpy compared to those for the melting of GST, providing key thermodynamic insights into the low-power switching of superlattice-based PCM. Nanocalorimetry measurements for Sb 2 Te 3 alone demonstrate an intrinsic premelting similar to the unique phase transition of superlattices, thus revealing a critical role of the Sb 2 Te 3 sublayer within our superlattices. These results advance our understanding of superlattices for energy-efficient data storage and computing.

Hafnia-based ferroelectric thin films are promising for semiconductor memory and neuromorphic computing applications. Amorphous, as-deposited, thin-film binary alloys of HfO 2 and ZrO 2 transform to the metastable, orthorhombic ferroelectric phase during post-deposition annealing and cooling. This transformation is generally thought to involve formation of a tetragonal precursor phase that distorts into the orthorhombic phase during cooling. In this work, we systematically study the effects of atomic layer deposition (ALD) temperature on the ferroelectricity of post-deposition-annealed Hf 0.5 Zr 0.5 O 2 (HZO) thin films. Seed crystallites having interplanar spacings consistent with the polar orthorhombic phase are observed by a plan-view transmission electron microscope in HZO thin films deposited at an elevated ALD temperature. After ALD under conditions that promote formation of these nanocrystallites, high-polarization ( P r > 18 μC/cm 2 ) ferroelectric switching is observed after rapid thermal annealing (RTA) at low temperature (350 °C). These results indicate the presence of minimal non-ferroelectric phases retained in the films after RTA when the ALD process forms nanocrystalline particles that seed subsequent formation of the polar orthorhombic phase.

Semiconducting carbon nanotubes are robust molecules with nanometer-scale diameters that can be used in field-effect transistors, from larger thin-film implementation to devices that work in conjunction with silicon electronics, and can potentially be used as a platform for high-performance digital electronics as well as radio-frequency and sensing applications. Recent progress in the materials, devices, and technologies related to carbon nanotube transistors is briefly reviewed. Emphasis is placed on the most broadly impactful advancements that have evolved from single-nanotube devices to implementations with aligned nanotubes and even nanotube thin films. There are obstacles that remain to be addressed, including material synthesis and processing control, device structure design and transport considerations, and further integration demonstrations with improved reproducibility and reliability; however, the integration of more than 10,000 devices in single functional chips has already been realized.

Scaling of monolayer transition metal dichalcogenide (TMD) field-effect transistors (FETs) is an important step toward evaluating the application space of TMD materials. Although some work on ultrashort channel monolayer (ML) TMD FETs has been published, there exist no comprehensive studies that assess their performance in a statistically relevant manner, providing critical insights into the impact of the device geometry. Part of the reason for the absence of such a study is the substantial variability of TMD devices when processes are not carefully controlled. In this work, we show a statistical study of ultrashort channel double-gated ML WS 2 FETs exhibiting excellent device performance and limited device-to-device variations. From a detailed analysis of cross-sectional scanning transmission electron microscopy (STEM) images and careful technology computer aided design (TCAD) simulations, we evaluated, in particular, an unexpected deterioration of the subthreshold characteristics for our shortest devices. Two potential candidates for the observed behavior were identified, i.e., buckling of the TMD on the substrate and loss of gate control due to the source geometry and the high- k dielectric between the metal gate and the metal source electrode.

Superlattice (SL) phase change materials have shown promise to reduce the switching current and resistance drift of phase change memory (PCM). However, the effects of internal SL interfaces and intermixing on PCM performance remain unexplored, although these are essential to understand and ensure reliable memory operation. Here, using nanometer-thin layers of Ge 2 Sb 2 Te 5 and Sb 2 Te 3 in SL-PCM, we uncover that both switching current density ( J reset ) and resistance drift coefficient ( v ) decrease as the SL period thickness is reduced (i.e., higher interface density); however, interface intermixing within the SL increases both. The signatures of distinct versus intermixed interfaces also show up in transmission electron microscopy, X-ray diffraction, and thermal conductivity measurements of our SL films. Combining the lessons learned, we simultaneously achieve low J reset ≈ 3-4 MA/cm 2 and ultralow v ≈ 0.002 in mushroom-cell SL-PCM with ∼110 nm bottom contact diameter, thus advancing SL-PCM technology for high-density storage and neuromorphic applications.

Realizing increasingly complex artificial intelligence (AI) functionalities directly on edge devices calls for unprecedented energy efficiency of edge hardware. Compute-in-memory (CIM) based on resistive random-access memory (RRAM) 1 promises to meet such demand by storing AI model weights in dense, analogue and non-volatile RRAM devices, and by performing AI computation directly within RRAM, thus eliminating power-hungry data movement between separate compute and memory 2-5 . Although recent studies have demonstrated in-memory matrix-vector multiplication on fully integrated RRAM-CIM hardware 6-17 , it remains a goal for a RRAM-CIM chip to simultaneously deliver high energy efficiency, versatility to support diverse models and software-comparable accuracy. Although efficiency, versatility and accuracy are all indispensable for broad adoption of the technology, the inter-related trade-offs among them cannot be addressed by isolated improvements on any single abstraction level of the design. Here, by co-optimizing across all hierarchies of the design from algorithms and architecture to circuits and devices, we present NeuRRAM-a RRAM-based CIM chip that simultaneously delivers versatility in reconfiguring CIM cores for diverse model architectures, energy efficiency that is two-times better than previous state-of-the-art RRAM-CIM chips across various computational bit-precisions, and inference accuracy comparable to software models quantized to four-bit weights across various AI tasks, including accuracy of 99.0 percent on MNIST 18 and 85.7 percent on CIFAR-10 19 image classification, 84.7-percent accuracy on Google speech command recognition 20 , and a 70-percent reduction in image-reconstruction error on a Bayesian image-recovery task., (© 2022. The Author(s).)

Background: Near-infrared indocyanine green fluorescence cholangiography (NIRF) has shown promising results on delineating extra-hepatic biliary anatomy during laparoscopic cholecystectomy to avoid bile duct injury. However its routine usage remains in question. In this study, the technique was evaluated further with learning curve estimation and learning factors were observed., Methods: One hundred ninety-nine cases which underwent laparoscopic cholecystectomy for acute or chronic cholecystitis within a 2-year period including 51 cases with initial use of NIRF by 2 surgeons were studied retrospectively. The learning curve was evaluated for a surgeon as primary objective. A case-matched comparison of the operative time between NIRF and conventional group, in terms of acute and chronic cholecystitis was also conducted as a secondary calculation., Results: Learning curve was evaluated with 61% learning rate for NIRF experience. Cysto-biliary junction non-illuminated cases under fluorescent view, had mean operative time of 80.83 ± 22.82 min, which was shorter than the cysto-biliary junction illuminated cases. The NIRF group exhibited longer operative time compared with the conventional group with mean difference of 34.39 min (significant at P < .05)., Conclusions: While the initial learning phase might be affected by surgeons' behavior and attitude, our results may provide a reference to learn at one's own pace and to employ NIRF teaching strategies during surgical training programs to overcome the initial phase during training period itself and facilitate universal achievement.

Phase-change memory (PCM) is a promising candidate for data storage in flexible electronics, but its high switching current and power are often drawbacks. In this study, we demonstrate a switching current density of ~0.1 mega-ampere per square centimeter in flexible superlattice PCM, a value that is one to two orders of magnitude lower than in conventional PCM on flexible or silicon substrates. This reduced switching current density is enabled by heat confinement in the superlattice material, assisted by current confinement in a pore-type device and the thermally insulating flexible substrate. Our devices also show multilevel operation with low resistance drift. The low switching current and good resistance on/off ratio are retained before, during, and after repeated bending and cycling. These results pave the way to low-power memory for flexible electronics and also provide key insights for PCM optimization on conventional silicon substrates.

Two-dimensional (2D) semiconductors have been proposed for heterogeneous integration with existing silicon technology; however, their chemical vapor deposition (CVD) growth temperatures are often too high. Here, we demonstrate direct CVD solid-source precursor synthesis of continuous monolayer (1L) MoS 2 films at 560 °C in 50 min, within the 450-to-600 °C, 2 h thermal budget window required for back-end-of-the-line compatibility with modern silicon technology. Transistor measurements reveal on-state current up to ∼140 μA/μm at 1 V drain-to-source voltage for 100 nm channel lengths, the highest reported to date for 1L MoS 2 grown below 600 °C using solid-source precursors. The effective mobility from transfer length method test structures is 29 ± 5 cm 2 V -1 s -1 at 6.1 × 10 12 cm -2 electron density, which is comparable to mobilities reported from films grown at higher temperatures. The results of this work provide a path toward the realization of high-quality, thermal-budget-compatible 2D semiconductors for heterogeneous integration with silicon manufacturing.

The success of semiconductor electronics is built on the creation of compact, low-power switching elements that offer routing, logic and memory functions. The availability of nanoscale optical switches could have a similarly transformative impact on the development of dynamic and programmable metasurfaces, optical neural networks and quantum information processing. Phase-change materials are uniquely suited to enable their creation as they offer high-speed electrical switching between amorphous and crystalline states with notably different optical properties. Their high refractive index has already been harnessed to fashion them into compact optical antennas. Here, we take the next important step, by showing electrically-switchable phase-change antennas and metasurfaces that offer strong, reversible, non-volatile, multi-phase switching and spectral tuning of light scattering in the visible and near-infrared spectral ranges. Their successful implementation relies on a careful joint thermal and optical optimization of the antenna elements that comprise a silver strip that simultaneously serves as a plasmonic resonator and a miniature heating stage. Our metasurface affords electrical modulation of the reflectance by more than fourfold at 755 nm.

High-density memory arrays require selector devices, which enable selection of a specific memory cell within a memory array by suppressing leakage current through unselected cells. Such selector devices must have highly nonlinear current-voltage characteristics and excellent endurance; thus selectors based on a tunneling mechanism present advantages over those based on the physical motion of atoms or ions. Here, we use two-dimensional (2D) materials to build an ultrathin (three-monolayer-thick) tunneling-based memory selector. Using a sandwich of h -BN, MoS 2 , and h -BN monolayers leads to an "H-shaped" energy barrier in the middle of the heterojunction, which nonlinearly modulates the tunneling current when the external voltage is varied. We experimentally demonstrate that tuning the MoS 2 Fermi level can improve the device nonlinearity from 10 to 25. These results provide a fundamental understanding of the tunneling process through atomically thin 2D heterojunctions and lay the foundation for developing high endurance selectors with 2D heterojunctions, potentially enabling high-density non-volatile memory systems.

The rapid growth and development of technology has had significant implications for healthcare, personalized medicine, and our understanding of biology. In this work, we leverage the miniaturization of electronics to realize the first demonstration of wireless detection and communication of an electronic device inside a cell. This is a significant forward step towards a vision of non-invasive, intracellular wireless platforms for single-cell analyses. We demonstrate that a 25 [Formula: see text]m wireless radio frequency identification (RFID) device can not only be taken up by a mammalian cell but can also be detected and specifically identified externally while located intracellularly. The S-parameters and power delivery efficiency of the electronic communication system is quantified before and after immersion in a biological environment; the results show distinct electrical responses for different RFID tags, allowing for classification of cells by examining the electrical output noninvasively. This versatile platform can be adapted for realization of a broad modality of sensors and actuators. This work precedes and facilitates the development of long-term intracellular real-time measurement systems for personalized medicine and furthering our understanding of intrinsic biological behaviors. It helps provide an advanced technique to better assess the long-term evolution of cellular physiology as a result of drug and disease stimuli in a way that is not feasible using current methods.

Background/aim: The aim of the study was to compare the outcomes of anatomical resection (AR) versus non-anatomical resection (NAR) for Japanese and Taiwanese patients with single, resectable hepatocellular carcinoma (HCC)., Patients and Methods: A propensity score matched (PSM) analysis was performed to compare the outcomes of the AR group to those of the NAR group. Tumor size <5 cm, T1 or T2 grade, without evidence of extrahepatic metastasis, invasion of portal or hepatic veins, or direct invasion of adjacent organs, were included in the study., Results: A total of 385 cases (Taiwanese 105, Japanese 280) were analyzed. After PSM, a total of 152 cases remain (Taiwan and Japan both 76 cases). Disease-free survival (DFS) and overall survival (OS) data were not significantly different between the two groups at 5 years follow-up., Conclusion: AR of HCC in Japanese patients has a similar 5-year DFS and OS as NAR of HCC in Taiwanese patients., (Copyright© 2020, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

The giant isopod genus Bathynomus A. Milne-Edwards, 1879, is recorded for the first time in Indonesian waters, from deep waters off southern Java in the Indian Ocean. Bathynomus raksasa sp. nov. is described and notes on juvenile specimens of an unidentified species found in the same locality are also provided. Bathynomus raksasa sp. nov. is characterized by the large size (averaging at 330 mm), narrowly rounded clypeus apex, prominent longitudinal carina on the clypeus, convex lateral margins of the uropodal exopod and endopod, produced distolateral corners of the uropodal exopod and endopod which have acute ends, an uropodal exopod with a setal fringe of medium length (69%), a pleotelson 1.6 times wider than long with the posterior margin medially concave, and the large number (11-13) of spines on the pleotelson., (Conni Sidabalok, Helen P.-S. Wong, Peter Ng.)

Ultrathin two-dimensional (2D) semiconducting layered materials offer great potential for extending Moore's law of the number of transistors in an integrated circuit 1 . One key challenge with 2D semiconductors is to avoid the formation of charge scattering and trap sites from adjacent dielectrics. An insulating van der Waals layer of hexagonal boron nitride (hBN) provides an excellent interface dielectric, efficiently reducing charge scattering 2,3 . Recent studies have shown the growth of single-crystal hBN films on molten gold surfaces 4 or bulk copper foils 5 . However, the use of molten gold is not favoured by industry, owing to its high cost, cross-contamination and potential issues of process control and scalability. Copper foils might be suitable for roll-to-roll processes, but are unlikely to be compatible with advanced microelectronic fabrication on wafers. Thus, a reliable way of growing single-crystal hBN films directly on wafers would contribute to the broad adoption of 2D layered materials in industry. Previous attempts to grow hBN monolayers on Cu (111) metals have failed to achieve mono-orientation, resulting in unwanted grain boundaries when the layers merge into films 6,7 . Growing single-crystal hBN on such high-symmetry surface planes as Cu (111) 5,8 is widely believed to be impossible, even in theory. Nonetheless, here we report the successful epitaxial growth of single-crystal hBN monolayers on a Cu (111) thin film across a two-inch c-plane sapphire wafer. This surprising result is corroborated by our first-principles calculations, suggesting that the epitaxial growth is enhanced by lateral docking of hBN to Cu (111) steps, ensuring the mono-orientation of hBN monolayers. The obtained single-crystal hBN, incorporated as an interface layer between molybdenum disulfide and hafnium dioxide in a bottom-gate configuration, enhanced the electrical performance of transistors. This reliable approach to producing wafer-scale single-crystal hBN paves the way to future 2D electronics.

Vanadium dioxide (VO 2 ) has been widely studied for its rich physics and potential applications, undergoing a prominent insulator-metal transition (IMT) near room temperature. The transition mechanism remains highly debated, and little is known about the IMT at nanoscale dimensions. To shed light on this problem, here we use ∼1 nm-wide carbon nanotube (CNT) heaters to trigger the IMT in VO 2 . Single metallic CNTs switch the adjacent VO 2 at less than half the voltage and power required by control devices without a CNT, with switching power as low as ∼85 μW at 300 nm device lengths. We also obtain potential and temperature maps of devices during operation using Kelvin probe microscopy and scanning thermal microscopy. Comparing these with three-dimensional electrothermal simulations, we find that the local heating of the VO 2 by the CNT plays a key role in the IMT. These results demonstrate the ability to trigger IMT in VO 2 using nanoscale heaters and highlight the significance of thermal engineering to improve device behavior.

As the physical dimensions of a transistor gate continue to shrink to a few atoms, performance can be increasingly determined by the limited electronic density of states (DOS) in the gate and the gate quantum capacitance ( C Q ). We demonstrate the impact of gate C Q and the dimensionality of the gate electrode on the performance of nanoscale transistors through analytical electrostatics modeling. For low-dimensional gates, the gate charge can limit the channel charge, and the transfer characteristics of the device become dependent on the gate DOS. We experimentally observe for the first time, room-temperature gate quantization features in the transfer characteristics of single-walled carbon nanotube (CNT)-gated ultrathin silicon-on-insulator (SOI) channel transistors; features which can be attributed to the Van Hove singularities in the one-dimensional DOS of the CNT gate. In addition to being an important aspect of future transistor design, potential applications of this phenomenon include multilevel transistors with suitable transfer characteristics obtained via engineered gate DOS.

The recent surge of interest in brain-inspired computing and power-efficient electronics has dramatically bolstered development of computation and communication using neuron-like spiking signals. Devices that can produce rapid and energy-efficient spiking could significantly advance these applications. Here we demonstrate direct current or voltage-driven periodic spiking with sub-20 ns pulse widths from a single device composed of a thin VO 2 film with a metallic carbon nanotube as a nanoscale heater, without using an external capacitor. Compared with VO 2 -only devices, adding the nanotube heater dramatically decreases the transient duration and pulse energy, and increases the spiking frequency, by up to 3 orders of magnitude. This is caused by heating and cooling of the VO 2 across its insulator-metal transition being localized to a nanoscale conduction channel in an otherwise bulk medium. This result provides an important component of energy-efficient neuromorphic computing systems and a lithography-free technique for energy-scaling of electronic devices that operate via bulk mechanisms.

Rationale: Gene expression of BAL cells, which samples the cellular milieu within the lower respiratory tract, has not been well studied in severe asthma. Objectives: To identify new biomolecular mechanisms underlying severe asthma by an unbiased, detailed interrogation of global gene expression. Methods: BAL cell expression was profiled in 154 asthma and control subjects. Of these participants, 100 had accompanying airway epithelial cell gene expression. BAL cell expression profiles were related to participant (age, sex, race, and medication) and sample traits (cell proportions), and then severity-related gene expression determined by correlating transcripts and coexpression networks to lung function, emergency department visits or hospitalizations in the last year, medication use, and quality-of-life scores. Measurements and Main Results: Age, sex, race, cell proportions, and medications strongly influenced BAL cell gene expression, but leading severity-related genes could be determined by carefully identifying and accounting for these influences. A BAL cell expression network enriched for cAMP signaling components most differentiated subjects with severe asthma from other subjects. Subsequently, an in vitro cellular model showed this phenomenon was likely caused by a robust upregulation in cAMP-related expression in nonsevere and β-agonist-naive subjects given a β-agonist before cell collection. Interestingly, ELISAs performed on BAL lysates showed protein levels may partly disagree with expression changes. Conclusions: Gene expression in BAL cells is influenced by factors seldomly considered. Notably, β-agonist exposure likely had a strong and immediate impact on cellular gene expression, which may not translate to important disease mechanisms or necessarily match protein levels. Leading severity-related genes were discovered in an unbiased, system-wide analysis, revealing new targets that map to asthma susceptibility loci.

The development of silicon semiconductor technology has produced breakthroughs in electronics-from the microprocessor in the late 1960s to early 1970s, to automation, computers and smartphones-by downscaling the physical size of devices and wires to the nanometre regime. Now, graphene and related two-dimensional (2D) materials offer prospects of unprecedented advances in device performance at the atomic limit, and a synergistic combination of 2D materials with silicon chips promises a heterogeneous platform to deliver massively enhanced potential based on silicon technology. Integration is achieved via three-dimensional monolithic construction of multifunctional high-rise 2D silicon chips, enabling enhanced performance by exploiting the vertical direction and the functional diversification of the silicon platform for applications in opto-electronics and sensing. Here we review the opportunities, progress and challenges of integrating atomically thin materials with silicon-based nanosystems, and also consider the prospects for computational and non-computational applications.

Neuromorphic visual systems have considerable potential to emulate basic functions of the human visual system even beyond the visible light region. However, the complex circuitry of artificial visual systems based on conventional image sensors, memory and processing units presents serious challenges in terms of device integration and power consumption. Here we show simple two-terminal optoelectronic resistive random access memory (ORRAM) synaptic devices for an efficient neuromorphic visual system that exhibit non-volatile optical resistive switching and light-tunable synaptic behaviours. The ORRAM arrays enable image sensing and memory functions as well as neuromorphic visual pre-processing with an improved processing efficiency and image recognition rate in the subsequent processing tasks. The proof-of-concept device provides the potential to simplify the circuitry of a neuromorphic visual system and contribute to the development of applications in edge computing and the internet of things.

Carbon nanotube (CNT) thin-film transistor (TFT) is a promising candidate for flexible and wearable electronics. However, it usually suffers from low semiconducting tube purity, low device yield, and the mismatch between p- and n-type TFTs. Here, we report low-voltage and high-performance digital and analog CNT TFT circuits based on high-yield (19.9%) and ultrahigh purity (99.997%) polymer-sorted semiconducting CNTs. Using high-uniformity deposition and pseudo-CMOS design, we demonstrated CNT TFTs with good uniformity and high performance at low operation voltage of 3 V. We tested forty-four 2-µm channel 5-stage ring oscillators on the same flexible substrate (1,056 TFTs). All worked as expected with gate delays of 42.7 ± 13.1 ns. With these high-performance TFTs, we demonstrated 8-stage shift registers running at 50 kHz and the first tunable-gain amplifier with 1,000 gain at 20 kHz. These results show great potentials of using solution-processed CNT TFTs for large-scale flexible electronics.

Carbon nanotube field-effect transistors (CNFETs) promise to improve the energy efficiency, speed, and transistor density of very large scale integration circuits owing to the intrinsic thin channel body and excellent charge transport properties of carbon nanotubes. Low-temperature fabrication (e.g., <400 °C) is a key enabler for the monolithic three-dimensional (3D) integration of CNFET digital logic into a device technology platform that overcomes memory bandwidth bottlenecks for data-abundant applications such as big-data analytics and machine learning. However, high contact resistance for short CNFET contacts has been a major roadblock to establishing CNFETs as a viable technology because the contact resistance, in series with the channel resistance, reduces the on-state current of CNFETs. Additionally, the variation in contact resistance remains unstudied for short contacts and will further degrade the energy efficiency and speed of CNFET circuits. In this work, we investigate by experiments the contact resistance and statistical variation of room-temperature fabricated CNFET contacts down to 10 nm contact lengths. These CNFET contacts are ∼15 nm shorter than the state-of-the-art Si CMOS "7 nm node" contact length, allowing for multiple generations of future scaling of the transistor-contacted gate pitch. For the 10 nm contacts, we report contact resistance values down to 6.5 kΩ per source/drain contact for a single carbon nanotube (CNT) with a median contact resistance of 18.2 kΩ. The 10 nm contacts reduce the CNFET current by as little as 13% at V DS = 0.7 V compared with the best reported 200 nm contacts to date, corroborated by results in this work. Our analysis of R C from 232 single-CNT CNFETs between the long-contact (e.g., 200 nm) and short-contact (e.g., 10 nm) regimes quantifies the resistance variation and projects the impact on CNFET current variability versus the number of CNT in the transistor. The resistance distribution reveals contact-length-dependent R C variations become significant below 20 nm contact length. However, a larger source of CNFET resistance variation is apparent at all contact lengths used in this work. To further investigate the origins of this contact-length-independent resistance variation, we analyze the variation of R C in arrays of identical CNFETs along a single CNT of constant diameter and observe the random occurrence of high  R C , even on correlated CNFETs.

We investigate the valley Hall effect (VHE) in monolayer WSe 2 field-effect transistors using optical Kerr rotation measurements at 20 K. While studies of the VHE have so far focused on n -doped MoS 2 , we observe the VHE in WSe 2 in both the n - and p -doping regimes. Hole doping enables access to the large spin-splitting of the valence band of this material. The Kerr rotation measurements probe the spatial distribution of the valley carrier imbalance induced by the VHE. Under current flow, we observe distinct spin-valley polarization along the edges of the transistor channel. From analysis of the magnitude of the Kerr rotation, we infer a spin-valley density of 44 spins/μm, integrated over the edge region in the p -doped regime. Assuming a spin diffusion length less than 0.1 μm, this corresponds to a spin-valley polarization of the holes exceeding 1%.

The priority of synaptic device researches has been given to prove the device potential for the emulation of synaptic dynamics and not to functionalize further synaptic devices for more complex learning. Here, we demonstrate an optic-neural synaptic device by implementing synaptic and optical-sensing functions together on h-BN/WSe 2 heterostructure. This device mimics the colored and color-mixed pattern recognition capabilities of the human vision system when arranged in an optic-neural network. Our synaptic device demonstrates a close to linear weight update trajectory while providing a large number of stable conduction states with less than 1% variation per state. The device operates with low voltage spikes of 0.3 V and consumes only 66 fJ per spike. This consequently facilitates the demonstration of accurate and energy efficient colored and color-mixed pattern recognition. The work will be an important step toward neural networks that comprise neural sensing and training functions for more complex pattern recognition.

Near-infrared indocyanine green (ICG) fluorescence application in liver cancer surgery have been reported in the literature since 2008. To date, most reports emphasized not only to the safety, feasibility and reproducibility, but also the potential benefits of its clinical applications in term of demarcating segmentation for an anatomical resection, tumor identification to achieve tumor free resection margin, detection of small unidentifiable subcapsular nodules as well as extrahepatic metastatic lesions, and fluorescence cholangiography. The purpose of this review is to present the fundamental concept of the interpretation of fluorescence enhancement by different timing through intravascular ICG distribution to liver and biliary washout; to describe step-by-step technical aspects of its use in different purposes, and to expose the diagnostic and therapeutic perspectives of this innovative imaging technique in liver cancer surgery., Competing Interests: Conflicts of Interest: The authors have no conflicts of interest to declare.

Black phosphorus (BP) is a promising two-dimensional (2D) material for nanoscale transistors, due to its expected higher mobility than other 2D semiconductors. While most studies have reported ambipolar BP with a stronger p-type transport, it is important to fabricate both unipolar p- and n-type transistors for low-power digital circuits. Here, we report unipolar n-type BP transistors with low work function Sc and Er contacts, demonstrating a record high n-type current of 200 μA/μm in 6.5 nm thick BP. Intriguingly, the electrical transport of the as-fabricated, capped devices changes from ambipolar to n-type unipolar behavior after a month at room temperature. Transmission electron microscopy analysis of the contact cross-section reveals an intermixing layer consisting of partly oxidized metal at the interface. This intermixing layer results in a low n-type Schottky barrier between Sc and BP, leading to the unipolar behavior of the BP transistor. This unipolar transport with a suppressed p-type current is favorable for digital logic circuits to ensure a lower off-power consumption.

Continuous monitoring of physiological parameters inside a living cell will lead to major advances in our understanding of biology and complex diseases, such as cancer. It also enables the development of new medical diagnostics and therapeutics. Progress in nanofabrication and wireless communication has opened up the potential of making a wireless chip small enough that it can be wholly inserted into a living cell. To investigate how such chips could be internalized into various types of living single cells and how this process might affect cells' physiology, we designed and fabricated a series of multilayered micron-scale tag structures with different sizes as potential RFID (Radio Frequency IDentification) cell trackers. While the present structures are test structures that do not resonate, the tags that do resonate have similar structure from device fabrication, material properties, and device size point of view. The structures are in four different sizes, the largest with the lateral dimension of 9 μm × 21 μm. The thickness for these structures is kept constant at 1.5 μm. We demonstrate successful delivery of our fabricated chips into various types of living cells, such as melanoma skin cancer, breast cancer, colon cancer and healthy/normal fibroblast skin cells. To our surprise, we observed a remarkable internalization rate difference between each cell type; the uptake rate was faster for more aggressive cancer cells than the normal/healthy cells. Cell viability before and after tag cellular internalization and persistence of the internalized tags have also been recorded over the course of five days of incubation. These results establish the foundations of the possibility of long term, wireless, intracellular physiological signal monitoring.

The computing demands of future data-intensive applications will greatly exceed the capabilities of current electronics, and are unlikely to be met by isolated improvements in transistors, data storage technologies or integrated circuit architectures alone. Instead, transformative nanosystems, which use new nanotechnologies to simultaneously realize improved devices and new integrated circuit architectures, are required. Here we present a prototype of such a transformative nanosystem. It consists of more than one million resistive random-access memory cells and more than two million carbon-nanotube field-effect transistors-promising new nanotechnologies for use in energy-efficient digital logic circuits and for dense data storage-fabricated on vertically stacked layers in a single chip. Unlike conventional integrated circuit architectures, the layered fabrication realizes a three-dimensional integrated circuit architecture with fine-grained and dense vertical connectivity between layers of computing, data storage, and input and output (in this instance, sensing). As a result, our nanosystem can capture massive amounts of data every second, store it directly on-chip, perform in situ processing of the captured data, and produce 'highly processed' information. As a working prototype, our nanosystem senses and classifies ambient gases. Furthermore, because the layers are fabricated on top of silicon logic circuitry, our nanosystem is compatible with existing infrastructure for silicon-based technologies. Such complex nano-electronic systems will be essential for future high-performance and highly energy-efficient electronic systems.

Selective extraction of semiconducting carbon nanotubes is a key step in the production of high-performance, solution-processed electronics. Here, we describe the ability of a supramolecular sorting polymer to selectively disperse semiconducting carbon nanotubes from five commercial sources with diameters ranging from 0.7 to 2.2 nm. The sorting purity of the largest-diameter nanotubes (1.4 to 2.2 nm; from Tuball) was confirmed by short channel measurements to be 97.5%. Removing the sorting polymer by acid-induced disassembly increased the transistor mobility by 94 and 24% for medium-diameter and large-diameter carbon nanotubes, respectively. Among the tested single-walled nanotube sources, the highest transistor performance of 61 cm 2 /V·s and on/off ratio >10 4 were realized with arc discharge carbon nanotubes with a diameter range from 1.2 to 1.7 nm. The length and quality of nanotubes sorted from different sources is compared using measurements from atomic force microscopy and Raman spectroscopy. The transistor mobility is found to correlate with the G/D ratio extracted from the Raman spectra.