Inhibiting Mg Diffusion and Evaporation by Forming Mg-Rich Reservoir at Grain Boundaries Improves the Thermal Stability of N-Type Mg3 Sb2 Thermoelectrics.

N-type Mg3 Sb2 -based thermoelectric materials show great promise in power generation due to their mechanical robustness, low cost of Mg, and high figure of merit (ZT) over a wide range of temperatures. However, their poor thermal stability hinders their practical applications. Here, MgB2 is introduced to improve the thermal stability of n-type Mg3 Sb2 . Enabled by MgB2 decomposition, extra Mg can be released into the matrix for Mg compensation thermodynamically, and secondary phases of Mg─B compounds can kinetically prevent Mg diffusion along grain boundaries. These synergetic effects inhibit the formation of Mg vacancies at elevated temperatures, thereby enhancing the thermal stability of n-type Mg3 Sb2 . Consequently, the Mg3.05 (Sb0.75 Bi0.25 )1.99 Te0.01 (MgB2 )0.03 sample exhibits negligible variation in thermoelectric performance during the 120-hour continuous measurement at 673 K. Moreover, the ZT of n-type Mg3 Sb2 can be maintained by adding MgB2 , reaching a high average ZT of ≈1.1 within 300-723 K. An eight-pair Mg3 Sb2 -GeTe-based thermoelectric device is also fabricated, achieving an energy conversion efficiency of ≈5.7% at a temperature difference of 438 K with good thermal stability. This work paves a new way to enhance the long-term thermal stability of n-type Mg3 Sb2 -based alloys and other thermoelectrics for practical applications.

Self-Assembled Au Nanoelectrodes: Enabling Low-Threshold-Voltage HfO2-Based Artificial Neurons.

Filamentary-type resistive switching devices, such as conductive bridge random-access memory and valence change memory, have diverse applications in memory and neuromorphic computing. However, the randomness in filament formation poses challenges to device reliability and uniformity. To overcome this issue, various defect engineering methods have been explored, including doping, metal nanoparticle embedding, and extended defect utilization. In this study, we present a simple and effective approach using self-assembled uniform Au nanoelectrodes to controll filament formation in HfO2 resistive switching devices. By concentrating the electric field near the Au nanoelectrodes within the BaTiO3 matrix, we significantly enhanced the device stability and reduced the threshold voltage by up to 45% in HfO2-based artificial neurons compared to the control devices. The threshold voltage reduction is attributed to the uniformly distributed Au nanoelectrodes in the insulating matrix, as confirmed by COMSOL simulation. Our findings highlight the potential of nanostructure design for precise control of filamentary-type resistive switching devices.

Why In2O3 Can Make 0.7 nm Atomic Layer Thin Transistors.

In this work, we demonstrate enhancement-mode field-effect transistors by an atomic-layer-deposited (ALD) amorphous In2O3 channel with thickness down to 0.7 nm. Thickness is found to be critical on the materials and electron transport of In2O3. Controllable thickness of In2O3 at atomic scale enables the design of sufficient 2D carrier density in the In2O3 channel integrated with the conventional dielectric. The threshold voltage and channel carrier density are found to be considerably tuned by channel thickness. Such a phenomenon is understood by the trap neutral level (TNL) model, where the Fermi-level tends to align deeply inside the conduction band of In2O3 and can be modulated to the bandgap in atomic layer thin In2O3 due to the quantum confinement effect, which is confirmed by density function theory (DFT) calculation. The demonstration of enhancement-mode amorphous In2O3 transistors suggests In2O3 is a competitive channel material for back-end-of-line (BEOL) compatible transistors and monolithic 3D integration applications.

Cellulose-Derived Hierarchical g-C3N4/TiO2-Nanotube Heterostructured Composites with Enhanced Visible-Light Photocatalytic Performance.

A novel cellulose-derived hierarchical g-C3N4/TiO2-nanotube heterostructured nanocomposite was fabricated by in situ coating thin g-C3N4 layers onto the surfaces of the TiO2 nanotubes, which were synthesized by utilizing the natural cellulose substance (e.g., commercial ordinary filter paper) as the structural template. These g-C3N4/TiO2-nanotube composites with varied thicknesses (ca. 3-30 nm) of the outer g-C3N4 layers displayed improved visible-light (λ > 420 nm)-driven photocatalytic degradation performances toward methylene blue. The optimal nanocomposite with an outer g-C3N4 layer of ca. 7.5 nm composed of 46 wt % g-C3N4 displayed an apparent rate constant of 0.0035 min-1, which was 8.5- and 4-fold larger than those of the referential TiO2-nanotube and g-C3N4 powder. The excellent and durable photocatalytic activities of these cellulose-derived g-C3N4/TiO2-nanotube composites were ascribed to their hierarchically network porous structures replicated from the cellulose template, as well as the formation of close heterojunctions in-between the g-C3N4 and TiO2 phases. Moreover, it was demonstrated that the photocatalytic mechanism matched with the type-II heterostructured model, while the main effective species during the photocatalytic processes of the nanocomposite were proved to be superoxide radicals.

Natural Cellulose Derived Nanocomposites as Anodic Materials for Lithium-Ion Batteries.

Bio-inspired synthetic method provides an effective shortcut to fabricate functional nanostructured materials with specific morphologies and designed functionalities. Natural cellulose substances (e. g., commercial laboratory cellulose filter paper) possesses unique three-dimensionally cross-linked porous structures and abundant functional groups for the functional modification on the surfaces. The deposition of metal oxide gel film on the surfaces of the cellulose nanofibers is facilely to be achieved through the surface sol-gel process, resulting in metal oxide replicas of the initial cellulose substance or metal-oxide/carbon nanocomposites. Moreover, the as-deposited metal oxide gel films coated on the cellulose fiber surfaces provide ideal platforms for the further formation of specific functional assemblies, and eventually to the corresponding nanocomposite materials. Based on this methodology, various nanostructured composites were prepared and employed as anodic materials for lithium-ion batteries, including metal-oxides-based (such as SnO2 , TiO2 , MoO3 , Fex Oy , and SiO2 ) and Si-based composites, as summarized in this personal account. Benefiting from the unique hierarchically porous network structures and the synergistic effects among the composite components of the anodic materials, the transfer of electrons/ions is accelerated and the structural stability of the electrode is enhanced, leading to the improved lithium storage performances and promoted cycling stability.

Electrophysiological Measurement of Rat Atrial Epicardium Using a Novel Stereotaxic Apparatus.

Flexible, in vivo maneuverable electrophysiology mapping techniques are not available in rat models. A novel cardiac stereotactic electrophysiology epicardial mapping system (CREAMS) allows for various measurements, including: (1) recording unipolar electrograms at multiple sites; (2) positioning of mapped sites and precision testing (Distance between the two "centers" = 297 ± 54 µm, n = 15); (3) evaluation of electrophysiology in an in vivo Sprague-Dawley rat model with high-frequency stimulation (HFS)-induced Atrial fibrillation (AF) at high right atrium (HRA) sites. We found that of the right atrium dispersion of effective refractory period (P < 0.05) and the window of vulnerability (P < 0.01) were significantly increased (P < 0.05) after HRA HFS. CREAMS has the potential for convenient electrophysiology assessment in a rat AF model through stereo-positioning, and flexible operating manipulation.

Review-Extremely Thin Amorphous Indium Oxide Transistors.

Amorphous oxide semiconductor transistors have been a mature technology in display panels for upward of a decade, and have recently been considered as promising back-end-of-line compatible channel materials for monolithic 3D applications. However, achieving high-mobility amorphous semiconductor materials with comparable performance to traditional crystalline semiconductors has been a long-standing problem. Recently it has been found that greatly reducing the thickness of indium oxide, enabled by an atomic layer deposition (ALD) process, can tune its material properties to achieve high mobility, high drive current, high on/off ratio, and enhancement-mode operation at the same time, beyond the capabilities of conventional oxide semiconductor materials. In this work, the history leading to the re-emergence of indium oxide, its fundamental material properties, growth techniques with a focus on ALD, state-of-the-art indium oxide device research, and the bias stability of the devices are reviewed.

A gut microbiota-bile acid axis promotes intestinal homeostasis upon aspirin-mediated damage.

Aspirin-related gastrointestinal damage is of growing concern. Aspirin use modulates the gut microbiota and associated metabolites, such as bile acids (BAs), but how this impacts intestinal homeostasis remains unclear. Herein, using clinical cohorts and aspirin-treated mice, we identified an intestinal microbe, Parabacteroides goldsteinii, whose growth is suppressed by aspirin. Mice supplemented with P. goldsteinii or its BA metabolite, 7-keto-lithocholic acid (7-keto-LCA), showed reduced aspirin-mediated damage of the intestinal niche and gut barrier, effects that were lost with a P. goldsteinii hdhA mutant unable to generate 7-keto-LCA. Specifically, 7-keto-LCA promotes repair of the intestinal epithelium by suppressing signaling by the intestinal BA receptor, farnesoid X receptor (FXR). 7-Keto-LCA was confirmed to be an FXR antagonist that facilitates Wnt signaling and thus self-renewal of intestinal stem cells. These results reveal the impact of oral aspirin on the gut microbiota and intestinal BA metabolism that in turn modulates gastrointestinal homeostasis.

Assessing potassium levels in critically ill patients with heart failure: application of a group-based trajectory model.

AIMS: Abnormalities in potassium homeostasis are frequently seen in hospitalized patients. A poor outcome in heart failure (HF) has been linked to both hypokalaemia and hyperkalaemia. The studies on the connection between variations in potassium levels and all-cause mortality remain scarce. We delineated trajectories of potassium levels and investigated the association of these trajectories with all-cause mortality of critically ill patients with HF. METHODS AND RESULTS: A retrospective analysis of blood potassium levels (9 times) in patients with HF after being admitted to the intensive care unit (ICU). Potassium levels were divided into three groups according to the first serum potassium level in ICU and thereafter categorized as follows: hypokalaemia group (n = 336) (<3.5 mmol/L), normal blood potassium-level group (n = 3322) (3.5-5.0 mmol/L), and hyperkalaemia group (n = 395) (>5.0 mmol/L). According to the group-based trajectory modelling (GBTM), the hyperkalaemia group and the normal blood potassium-level group can be divided into three trajectory groups: the low-level stable group, the medium-level stable group, and the high-level decline group. The hypokalaemia group can be divided into two trajectory groups: the low-level rise group and the high-level rise group. A total of 4053 HF patients were included (mean age 71.81 ± 13.12 years, 54.90% males, 45.10% females). After adjusting for possible confounding variables, in the hyperkalaemia group, the low-level stable group had lower 28 day [high-level decline group vs. low-level stable group hazard ratio (HR), 95% confidence interval (CI): 2.917, 1.555-5.473; P < 0.05] and 365 day (high-level decline group vs. low-level stable group HR, 95% CI: 2.854, 1.820-4.475; P < 0.05) all-cause mortality. In the normal blood potassium-level group, the medium-level stable group had lower 28 day (medium-level stable group vs. low-level stable group HR, 95% CI: 0.776, 0.657-0.918; P < 0.05) and 365 day (medium-level stable group vs. low-level stable group HR, 95% CI: 0.827, 0.733-0.934; P < 0.05) all-cause mortality. In the hypokalaemia group, the cumulative survival of the high-level rise group and the low-level rise group did not differ significantly. CONCLUSIONS: Critically ill patients with HF have blood potassium trajectories. And the trajectories are associated with all-cause mortality for hyperkalaemia and normal blood potassium-level patients. GBTM is a granular method to describe the evolution of blood potassium, which may increase the current knowledge of blood potassium-level adjustment.

Impacts of Plant-derived Secondary Metabolites for Improving Flora in Type 2 Diabetes.

BACKGROUND: Diabetes has become a problem that plagues public healthcare systems. Recent studies have shown that intestinal flora exerts positive therapeutic effects on metabolic diseases, and plant-derived secondary metabolites are safe, effective and easy to prepare and also have an impact on intestinal flora and diabetes; these drugs have rarely been reviewed before as a class of drugs for diabetes, especially focusing on the intestinal flora. Therefore, studying the relationship between plant-derived secondary metabolites and diabetes mellitus is crucial. OBJECTIVE: The objective of this study is to summarize and investigate the therapeutic mechanism of drugs extracted from natural plants effects on type 2 diabetes mellitus. METHODS: The relationship between flora and type 2 diabetes was investigated by reviewing the recent experimental literature, and the pathways available for natural plant-derived secondary metabolites in the treatment of type 2 diabetes were summarized. RESULTS: The therapeutic mechanisms of common plant-derived secondary metabolites for type 2 diabetes were summarized with a focus on the prebiotic efficacy of natural plant-derived secondary metabolites and the modulation of intestinal flora, and the mechanisms through which plantderived secondary metabolites treat type 2 diabetes via effects on intestinal flora are further reviewed. CONCLUSION: Common plant-derived secondary metabolites can play a role in regulating bacteria in the intestinal tract by enriching beneficial bacteria and removing harmful bacteria to achieve their therapeutic effect on type 2 diabetes. In addition, due to their excellent ability to regulate intestinal flora, plant-derived secondary metabolites may also have excellent efficacy in cancer and obesity, among other diseases.

Hierarchical Bi2WO6/TiO2-nanotube composites derived from natural cellulose for visible-light photocatalytic treatment of pollutants.

A series of Bi2WO6/TiO2-nanotube (Bi2WO6/TiO2-NT) heterostructured composites were prepared by utilizing natural cellulose (e.g., laboratory filter paper) as the structural template. The obtained nanoarchitectonics, namely Bi2WO6/TiO2-NT nanocomposites, displayed three-dimensionally interwoven structures which replicated the initial cellulose template. The composite Bi2WO6/TiO2-NT nanotubes were formed by TiO2 nanotubes that uniformly anchored with Bi2WO6 nanoparticles of various densities on the surface. The composites exhibited improved photocatalytic activities toward the reduction of Cr(VI) and degradation of rhodamine B under visible light (λ > 420 nm), which were attributed to the uniform anchoring of Bi2WO6 nanoparticles on TiO2 nanotubes, as well as strong mutual effects and well-proportioned formation of heterostructures in between the Bi2WO6 and TiO2 phases. These improvements arose from the cellulose-derived unique structures, leading to an enhanced absorption of visible light together with an accelerated separation and transfer of the photogenerated electron-hole pairs of the nanocomposites, which resulted in increased effective amounts of photogenerated carriers for the photocatalytic reactions. It was demonstrated that the photoinduced electrons dominated the photocatalytic reduction of Cr(VI), while hydroxyl radicals and reactive holes contributed to the photocatalytic degradation of rhodamine B.

Development of a complete blood count with differential-based prediction model for in-hospital mortality among patients with acute myocardial infarction in the coronary care unit.

Purpose: In recent years, the complete blood count with differential (CBC w/diff) test has drawn strong interest because of its prognostic value in cardiovascular diseases. We aimed to develop a CBC w/diff-based prediction model for in-hospital mortality among patients with severe acute myocardial infarction (AMI) in the coronary care unit (CCU). Materials and methods: This single-center retrospective study used data from a public database. The neural network method was applied. The performance of the model was assessed by discrimination and calibration. The discrimination performance of our model was compared to that of seven other classical machine learning models and five well-studied CBC w/diff clinical indicators. Finally, a permutation test was applied to evaluate the importance rank of the predictor variables. Results: A total of 2,231 patient medical records were included. With a mean area under the curve (AUC) of 0.788 [95% confidence interval (CI), 0.736-0.838], our model outperformed all other models and indices. Furthermore, it performed well in calibration. Finally, the top three predictors were white blood cell count (WBC), red blood cell distribution width-coefficient of variation (RDW-CV), and neutrophil percentage. Surprisingly, after dropping seven variables with poor prediction values, the AUC of our model increased to 0.812 (95% CI, 0.762-0.859) (P < 0.05). Conclusion: We used a neural network method to develop a risk prediction model for in-hospital mortality among patients with AMI in the CCU based on the CBC w/diff test, which performed well and would aid in early clinical decision-making. The top three important predictors were WBC, RDW-CV and neutrophil percentage.

Nanometer-Thick Oxide Semiconductor Transistor with Ultra-High Drain Current.

High drive current is a critical performance parameter in semiconductor devices for high-speed, low-power logic applications or high-efficiency, high-power, high-speed radio frequency (RF) analogue applications. In this work, we demonstrate an In2O3 transistor grown by atomic layer deposition (ALD) at back-end-of-line (BEOL) compatible temperatures with a record high drain current in planar FET, exceeding 10 A/mm, the performance of which is 2-3 times better than all known transistors with semiconductor channels. A high transconductance reaches 4 S/mm, recorded among all transistors with a planar structure. Planar FETs working ballistically or quasi-ballistically are exploited as one of the simplest platforms to investigate the intrinsic transport properties. It is found experimentally and theoretically that a high carrier density and high electron velocity both contribute to this high on-state performance in ALD In2O3 transistors, which is made possible by the high-quality oxide/oxide interface, the metal-like charge-neutrality-level (CNL) alignment, and the high band velocities induced by the low density-of-state (DOS). Experimental Hall, I-V, and split C-V measurements at room temperature confirm a high carrier density of up to 6-7 × 1013 /cm2 and a high velocity of about 107 cm/s, well-supported by density functional theory (DFT) calculations. The simultaneous demonstration of such high carrier concentration and average band velocity is enabled by the exploitation of the ultrafast pulse scheme and heat dissipation engineering.

Natural Cellulose Substance Based Energy Materials.

Natural cellulose substances have been proven to be ideal structural templates and scaffolds for the fabrication of artificial functional materials with designed structures, psychochemical properties and functionalities. They possess unique hierarchically porous network structures with flexible, biocompatible, and environmental characteristics, exhibiting great potentials in the preparation of energy-related materials. This minireview summarizes natural cellulose-based materials that are used in batteries, supercapacitors, photocatalytic hydrogen generation, photoelectrochemical cells, and solar cells. When natural cellulose substances are employed as the structural template or carbon sources of energy materials, the three-dimensional porous interwoven structures are perfectly replicated, leading to the enhanced performances of the resultant materials. Benefiting from the mechanical strengths of natural cellulose substances, wearable, portable, free-standing, and flexible materials for energy storage and conversion are easily obtained by using natural cellulose substances as the substrates.

A Bio-Inspired Nanotubular Na2MoO4/TiO2 Composite as a High-Performance Anodic Material for Lithium-Ion Batteries.

A train of bio-inspired nanotubular Na2MoO4/TiO2 composites were synthesized by using a natural cellulose substance (e.g., commercial ordinary filter paper) as the structural template. The TiO2 gel films were coated on the cellulose nanofiber surfaces via a sol-gel method firstly, followed with the deposition of the poly(diallyldimethylammonium chloride)/Na2MoO4 (PDDA/Na2MoO4) bi-layers several times, through the layer-by-layer self-assembly route, yielding the (PDDA/Na2MoO4)n/TiO2-gel/cellulose composite, which was calcined in air to give various Na2MoO4/TiO2 nanocomposites containing different Na2MoO4 contents (15.4, 24.1, and 41.4%). The resultant nanocomposites all inherited the three-dimensionally porous network structure of the premier cellulose substance, which were formed by hierarchical TiO2 nanotubes anchored with the Na2MoO4 layers. When employed as anodic materials for lithium-ion batteries, those Na2MoO4/TiO2 nanocomposites exhibited promoted electrochemical performances in comparison with the Na2MoO4 powder and pure TiO2 nanotubes, which was resulted from the high capacity of the Na2MoO4 component and the buffering effects of the TiO2 nanotubes. Among all the nanotubular Na2MoO4/TiO2 composites, the one with a Na2MoO4 content of 41.4% showed the best electrochemical properties, such as the cycling stability with a capacity of 180.22 mAh g-1 after 200 charge/discharge cycles (current density: 100 mA g-1) and the optimal rate capability.

Hierarchical nanostructures derived from cellulose for lithium-ion batteries.

Introducing the sophisticated morphologies and structures of natural substances into artificial materials provides a promising strategy for the fabrication of functional materials with tailored structures and functionalities. Herein, our recent advances achieved in the fabrication of hierarchically structured functional materials derived from natural cellulose substances (e.g., ordinary laboratory filter paper) for lithium-ion batteries are reviewed. The surface sol-gel process was employed to fabricate metal oxides (Sn, Ti, Fe, etc.), silica and silicon based nanocomposites by using the corresponding metal alkoxides as the precursors, which faithfully inherited the unique porous network structures of the initial cellulose substances. However, the nanomaterials synthesized as such are limited to the above-mentioned species due to the limitation of specific metal alkoxide precursors used. To break this limitation, specific polyoxometalate clusters were employed as the building blocks to be assembled onto the surfaces of cellulose nanofibres and eventually to obtain the corresponding molybdenum based nanomaterials with three-dimensional porous network structures and specific properties. These cellulose derived nanocomposites exhibit improved lithium storage capacities and cycling stabilities when applied as anodic materials for lithium-ion batteries, resulting from the unique hierarchically porous network structures inherited from the initial cellulose substance and the strong synergistic interactions among the components contained therein.

A silver-nanoparticle/cellulose-nanofiber composite as a highly effective substrate for surface-enhanced Raman spectroscopy.

A highly active surface-enhanced Raman scattering (SERS) substrate was developed by facile deposition of silver nanoparticles onto cellulose fibers of ordinary laboratory filter paper. This was achieved by means of the silver mirror reaction in a manner to control both the size of the silver nanoparticles and the silver density of the substrate. This paper-based substrate is composed of a particle-on-fiber structure with the unique three-dimensional network morphology of the cellulose matrix. For such a SERS substrate with optimized size of the silver nanoparticles (ca. 70 nm) and loading density of silver (17.28 wt %), a remarkable detection limit down to the sub-attomolar (1 × 10-16 M) level and an enhancement factor of 3 × 106 were achieved by using Rhodamine 6G as the analyte. Moreover, this substrate was applied to monitor the molecular recognition through multiple hydrogen bonds in between nucleosides of adenosine and thymidine. This low-cost, highly sensitive, and biocompatible paper-based SERS substrate holds considerable potentials for the detection and analyses of chemical and biomolecular species.

Signature of quantum Griffiths singularity state in a layered quasi-one-dimensional superconductor.

Quantum Griffiths singularity was theoretically proposed to interpret the phenomenon of divergent dynamical exponent in quantum phase transitions. It has been discovered experimentally in three-dimensional (3D) magnetic metal systems and two-dimensional (2D) superconductors. But, whether this state exists in lower dimensional systems remains elusive. Here, we report the signature of quantum Griffiths singularity state in quasi-one-dimensional (1D) Ta2PdS5 nanowires. The superconducting critical field shows a strong anisotropic behavior and a violation of the Pauli limit in a parallel magnetic field configuration. Current-voltage measurements exhibit hysteresis loops and a series of multiple voltage steps in transition to the normal state, indicating a quasi-1D nature of the superconductivity. Surprisingly, the nanowire undergoes a superconductor-metal transition when the magnetic field increases. Upon approaching the zero-temperature quantum critical point, the system uncovers the signature of the quantum Griffiths singularity state arising from enhanced quenched disorders, where the dynamical critical exponent becomes diverging rather than being constant.

Chiral Landau levels in Weyl semimetal NbAs with multiple topological carriers.

Recently, Weyl semimetals have been experimentally discovered in both inversion-symmetry-breaking and time-reversal-symmetry-breaking crystals. The non-trivial topology in Weyl semimetals can manifest itself with exotic phenomena, which have been extensively investigated by photoemission and transport measurements. Despite the numerous experimental efforts on Fermi arcs and chiral anomaly, the existence of unconventional zeroth Landau levels, as a unique hallmark of Weyl fermions, which is highly related to chiral anomaly, remains elusive owing to the stringent experimental requirements. Here, we report the magneto-optical study of Landau quantization in Weyl semimetal NbAs. High magnetic fields drive the system toward the quantum limit, which leads to the observation of zeroth chiral Landau levels in two inequivalent Weyl nodes. As compared to other Landau levels, the zeroth chiral Landau level exhibits a distinct linear dispersion in magnetic field direction and allows the optical transitions without the limitation of zero z momentum or [Formula: see text] magnetic field evolution. The magnetic field dependence of the zeroth Landau levels further verifies the predicted particle-hole asymmetry of the Weyl cones. Meanwhile, the optical transitions from the normal Landau levels exhibit the coexistence of multiple carriers including an unexpected massive Dirac fermion, pointing to a more complex topological nature in inversion-symmetry-breaking Weyl semimetals. Our results provide insights into the Landau quantization of Weyl fermions and demonstrate an effective tool for studying complex topological systems.