Silicon flower structures by maskless plasma etching.

Silicon nano/microstructures are widely utilized in the semiconductor industry, and plasma etching is the most prominent method for fabricating silicon nano/microstructures. Among the variety of silicon nano/microstructures, black silicon with light-trapping properties has garnered broad interest from both the scientific and industrial communities. However, the fabrication mechanism of black silicon remains unclear, and the light absorption of black silicon only focuses on the near-infrared region thus far. Herein, we demonstrate that black silicon can be fabricated from individual flower-like silicon microstructures. Using fluorocarbon gases as etchants, silicon flower microstructures have been formed via maskless plasma etching. Black silicon forming from silicon flower microstructures exhibits strong absorption with wavelength from 0.25 µm to 20 µm. The result provides novel insight into the understanding of the plasma etching mechanism in addition to offering further significant practical applications for device manufacturing.

Nb2O5 Coating to Improve the Cyclic Stability and Voltage Decay of Li-Rich Cathode Material for Lithium-Ion Battery.

The commercialization of lithium manganese oxide (LMO) is seriously hindered by several drawbacks, such as low initial Coulombic efficiency, the degradation of the voltage and capacity during cycling, and the poor rating performance. Developing a simple and scalable synthesis for engineering with surface coating layers is significant and challenging for the commercial prospects of LMO oxides. Herein, we have proposed an efficient engineering strategy with a Nb2O5 coating layer. We dissolved niobate (V) ammonium oxalate hydrate and stoichiometric rich LMO (RLM) in deionized water and stirred constantly. Then, the target product was calcined at high temperature. The discharge capacity of the Nb2O5 coating RLM is increased from 195 mAh·g-1 (the RLM without Nb2O5) to 215 mAh·g-1 at a coating volume ratio of 0.010. The average voltage decay was 4.38 mV/cycle, which was far lower than the 7.50 mV/cycle for the pure LMO. The electrochemical kinetics results indicated that the performance was superior with the buffer engineering by the Nb2O5 coating of RLM, which provided an excellent lithium-ion conduction channel, and improved diffusion kinetics, capacity fading, and voltage decay. This reveals the strong potential of the Nb2O5 coating in the field of cathode materials for lithium-ion batteries.

Detection of Alpha-Fetoprotein Using Aptamer-Based Sensors.

Alpha-fetoprotein (AFP) is widely-known as the most commonly used protein biomarker for liver cancer diagnosis at the early stage. Therefore, developing the highly sensitive and reliable method of AFP detection is of essential demand for practical applications. Herein, two types of aptamer-based AFP detection methods, i.e., optical and electrochemical biosensors, are reviewed in detail. The optical biosensors include Raman spectroscopy, dual-polarization interferometry, resonance light-scattering, fluorescence, and chemiluminescence. The electrochemical biosensors include cyclic voltammetry, electrochemical impedance spectroscopy, and giant magnetic impedance. Looking into the future, methods for AFP detection that are high sensitivity, long-term stability, low cost, and operation convenience will continue to be developed.

Early clinical and CT features of COVID-19 and community-acquired pneumonia from a fever observation ward in Ningbo, China.

INTRODUCTION: We aimed to compare the early clinical manifestations, laboratory results and chest computed tomography (CT) images of COVID-19 patients with those of other community-acquired pneumonia (CAP) patients to differentiate CAP from COVID-19 before reverse transcription-polymerase chain reaction results are obtained. METHODS: The clinical and laboratory data and chest CT images of 51 patients were assessed in a fever observation ward for evidence of COVID-19 between January and February 2020. RESULTS: 24 patients had laboratory-confirmed COVID-19, whereas 27 individuals had negative results. No statistical difference in clinical features was found between COVID-19 and CAP patients, except for diarrhoea. There was a significant difference in lymphocyte and eosinophil counts between COVID-19 and CAP patients. In total, 22 (91.67%) COVID-19 patients had bilateral involvement and multiple lesions according to their lung CT images; the left lower lobe (87.50%) and right lower lobe (95.83%) were affected most often, and all lesions were located in the peripheral zones of the lung. The most common CT feature of COVID-19 was ground-glass opacity, found in 95.83% of patients, compared to 66.67% of CAP patients. CONCLUSION: Diarrhoea, lymphocyte counts, eosinophil counts and CT findings (e.g. ground-glass opacity) could help to distinguish COVID-19 from CAP at an early stage of infection, based on findings from our fever observation ward.

Transparent graphene electrodes based hybrid perovskites photodetectors with broad spectral response from UV-visible to near-infrared.

A new class of transparent graphene electrode based organic-inorganic halide perovskite photodetectors with broad spectral response is developed. These ultrasensitive devices exhibit high ON/OFF current ratio, high linear dynamic range, broad spectral range, excellent detection for weak light and easy fabrication with low-cost. Their semi-transparent feature and distinct photodetecting function for both sides would provide new applications affecting our daily lives.

Improved analytical model for the relaxation process of aeolian sand transport.

The process from the initial sand movement to sand flux saturation is described as the relaxation of aeolian sand transport. For this relaxation process, most existing models distinguish the conditions with and without upwind sand flux, therefore lacking in generality. An improved analytical model is proposed in this paper, which incorporates the phenomena of "overshoot" and "equilibrium" and the concept of the region of initiation by fluid, and is able to unify the cases with and without upwind sand flux. Within the proposed model, a new definition of the saturation length is proposed based on the analogy between two damping oscillation models, and its constancy is physically interpreted and verified with wind tunnel experimental data. In comparison with the existing models, the proposed model agrees better with the measurements of the process of sand transport, thereby shedding light on the understanding of aeolian sand transport under complex circumstances.

Detection of Mercury Ion with High Sensitivity and Selectivity Using a DNA/Graphene Oxide Hybrid Immobilized on Glass Slides.

Excessive mercury ions (Hg2+) cause great pollution to soil/water and pose a major threat to human health. The high sensitivity and high selectivity in the Hg2+ detection demonstrated herein are significant for the research areas of analytical chemistry, chemical biology, physical chemistry, drug discovery, and clinical diagnosis. In this study, a series of simple, low-cost, and highly sensitive biochips based on a graphene oxide (GO)/DNA hybrid was developed. Hg2+ is detected with high sensitivity and selectivity by GO/DNA hybrid biochips immobilized on glass slides. The performance of the biosensors can be improved by introducing more phosphorothioate sites and complementary bases. The best limit of detection of the biochips is 0.38 nM with selectivity of over 10:1. This sensor was also used for Hg2+ detection in Dendrobium. The results show this biochip is promising for Hg2+ detection.

The application of the scallop nanostructure in deep silicon etching.

Micro/nanostructures with high aspect ratios in silicon wafers obtained by plasma etching are of great significance in device fabrication. In most cases, the scallop nanostructure in deep silicon etching should be suppressed. However, the scallop nanostructure could be applied in electronic device fabrication as characteristic information, which indicates the balance between deposition and etching. In this work, the applications of scallop nanostructures in etching process optimization and environmental protection are demonstrated. In addition, the minimum effect of the cycle time on the scallop size is reported for the first time. These results could bring new thoughts to the electronic devices related fields, such as micro-electro-mechanical systems (MEMS), silicon capacitors and advanced packaging.

Direct observation of single-molecule hydrogen-bond dynamics with single-bond resolution.

The hydrogen bond represents a fundamental interaction widely existing in nature, which plays a key role in chemical, physical and biochemical processes. However, hydrogen bond dynamics at the molecular level are extremely difficult to directly investigate. Here, in this work we address direct electrical measurements of hydrogen bond dynamics at the single-molecule and single-event level on the basis of the platform of molecular nanocircuits, where a quadrupolar hydrogen bonding system is covalently incorporated into graphene point contacts to build stable supramolecule-assembled single-molecule junctions. The dynamics of individual hydrogen bonds in different solvents at different temperatures are studied in combination with density functional theory. Both experimental and theoretical results consistently show a multimodal distribution, stemming from the stochastic rearrangement of the hydrogen bond structure mainly through intermolecular proton transfer and lactam-lactim tautomerism. This work demonstrates an approach of probing hydrogen bond dynamics with single-bond resolution, making an important contribution to broad fields beyond supramolecular chemistry.

Chemically Engineered Substrates for Patternable Growth of Two-Dimensional Chalcogenide Crystals.

The key challenge of direct integration of two-dimensional (2D) chalcogenide crystals into functional modules is precise control of the nucleation sites of the building blocks. Herein, we exploit the chemical activities and surface engineering of the substrates to manipulate the nucleation energy barrier of 2D crystals and thereby realize the patternable growth of 2D crystals. The selective-region chemical modifications of the substrates are achieved via microcontact printing combined with the elegant self-assembly of octadecyltrichlorosilane molecules on the substrates. The patternable growth method is versatile and can be used as a general strategy for growing a broad class of high-quality 2D chalcogenide crystals with tailorable configurations on a variety of chemically engineered substrates. Moreover, we demonstrate flexible transparent electrodes based on large-scale patterned nanogrids of topological insulator Bi2Se3, which possess tailored trade-off between electric conductivity and optical transmittance across the visible to near-infrared regime. We hope this method may open an avenue to the efficient integration and batch production of 2D chalcogenide crystals and could inspire ongoing efforts of the fabrication of van der Waals heterostructures.

Primary diffuse large B-cell lymphoma of the left ureter: A case report.

Diffuse large B-cell lymphoma (DLBCL) is a subtype of non-Hodgkin lymphoma occurring in various sites, but rarely involving the ureters. Primary DLBCL is a rare entity. Imaging studies in a 82-year-old male patient revealed left hydronephrosis and an area of nodular soft tissue density in the upper ureteral wall. On enhanced computed tomography scans, the lesion exhibited early enhancement. As the lesion was considered to be malignant, a left nephroureterectomy was performed for the purpose of pathological diagnosis. Histological analysis and immunohistochemistry revealed DLBCL. Since the surgery, the patient has survived for 16 months without evidence of a relapse. Thus, in cases with ureteral stenosis or obstruction for which the cause is uncertain, the possibility of primary lymphoma of the ureter should be considered and further histopathological examination of bioptic samples should be performed as soon as possible.

Seed-Assisted Growth of Single-Crystalline Patterned Graphene Domains on Hexagonal Boron Nitride by Chemical Vapor Deposition.

Vertical heterostructures based on two-dimensional layered materials, such as stacked graphene and hexagonal boron nitride (G/h-BN), have stimulated wide interest in fundamental physics, material sciences and nanoelectronics. To date, it still remains challenging to obtain high quality G/h-BN heterostructures concurrently with controlled nucleation density and thickness uniformity. In this work, with the aid of the well-defined poly(methyl methacrylate) seeds, effective control over the nucleation densities and locations of graphene domains on the predeposited h-BN monolayers was realized, leading to the formation of patterned G/h-BN arrays or continuous films. Detailed spectroscopic and morphological characterizations further confirmed that ∼85.7% of such monolayer graphene domains were of single-crystalline nature with their domain sizes predetermined throughout seed interspacing. Density functional theory calculations suggested that a self-terminated growth mechanism can be applied for the related graphene growth on h-BN/Cu. In turn, as-constructed field-effect transistor arrays based on such synthesized single-crystalline G/h-BN patterning were found to be compatible with fabricating devices with nice and steady performance, hence holding great promise for the development of next-generation graphene-based electronics.

Oxidative-Etching-Assisted Synthesis of Centimeter-Sized Single-Crystalline Graphene.

Centimeter-sized single-crystalline graphene is obtained by an oxidative-etching-assisted chemical vapor deposition (CVD) method. Gaseous oxidants are found to be highly responsible for graphene etching. By diminishing the uncertain amount of H2 O vapor in commercial H2 and precisely introducing additional O2 , the graphene nucleation density can be well controlled.

Graphene-DNAzyme Junctions: A Platform for Direct Metal Ion Detection with Ultrahigh Sensitivity.

Many metal ions are present in biology and in the human body in trace amounts. Despite numerous efforts, metal sensors with ultrahigh sensitivity (< a few picomolar) are rarely achieved. Here, we describe a platform method that integrates a Cu2+-dependent DNAzyme into graphene-molecule junctions and its application for direct detection of paramagnetic Cu2+ with femtomolar sensitivity and high selectivity. Since DNAzymes specific for other metal ions can be obtained through in vitro selection, the method demonstrated here can be applied to the detection of a broad range of other metal ions.

Ultrahigh Photogain Nanoscale Hybrid Photodetectors.

A class of ultrasensitive nanoscale hybrid photodetectors formed from carbon electrode-molecule junctions using P3HT:PCBM as photoresponsive semiconductors are demonstrated. The unique device architecture, tunability of nanoscale channel lengths and the optimized contact nature of semiconductor/electrode interfaces led to ultrahigh photogains of 1000 with graphene nanoelectrodes and 1 000 000 with single-walled carbon nanotube nanoelectrodes.

Direct growth of high-quality graphene on high-κ dielectric SrTiO3 substrates.

High-quality monolayer graphene was synthesized on high-κ dielectric single crystal SrTiO3 (STO) substrates by a facile metal-catalyst-free chemical vapor deposition process. The as-grown graphene sample was suitable for fabricating a high performance field-effect transistor (FET), followed by a far lower operation voltage compared to that of a SiO2-gated FET and carrier motilities of approximately 870-1050 cm(2)·V(-1)·s(-1) in air at rt. The directly grown high-quality graphene on STO makes it a perfect candidate for designing transfer-free, energy-saving, and batch production of FET arrays.

A novel canine model of portal vein stenosis plus thioacetamide administration-induced cirrhotic portal hypertension with hypersplenism.

Current large animal models that could closely resemble the typical features of cirrhotic portal hypertension in human have not been well established. Thus, we aimed to develop and describe a reliable and reproducible canine cirrhosis model of portal hypertension. A total of 30 mongrel dogs were randomly divided into four groups: 1 (control; n = 5), 2 (portal vein stenosis [PVS]; n = 5], 3 (thioacetamide [TAA]; n = 5), and 4 (PVS plus TAA; n = 15). After 4-months modeling period, liver and spleen CT perfusion, abdominal CT scans, portal hemodynamics, gastroscopy, hepatic function, blood routine, the bone marrow, liver, and spleen histology were studied. The animals in group 2 (PVS) developed extrahepatic portosystemic collateral circulation, particularly esophageal varices, without hepatic cirrhosis and portal hypertension. Animals from group 3 (TAA) presented mild cirrhosis and portal hypertension without significant symptoms of esophageal varices and hypersplenism. In contrast, animals from group 4 (PVS + TAA) showed well-developed micronodular and macronodular cirrhosis, associated with significant portal hypertension and hypersplenism. The combination of PVS and TAA represents a novel, reliable, and reproducible canine cirrhosis model of portal hypertension, which is associated with the typical characteristics of portal hypertension, including hypersplenism.