Pressure-Modulated Structural and Magnetic Phase Transitions in Two-Dimensional FeTe: Tetragonal and Hexagonal Polymorphs.

Two-dimensional (2D) Fe chalcogenides with their rich structures and properties are highly desirable for revealing the torturous transition mechanism of Fe chalcogenides and exploring their potential applications in spintronics and nanoelectronics. Hydrostatic pressure can effectively stimulate phase transitions between various ordered states, allowing one to successfully plot a phase diagram for a given material. Herein, the structural evolution and transport characteristics of 2D FeTe were systematically investigated under extreme conditions by comparing two distinct symmetries, i.e., tetragonal (t) and hexagonal (h) FeTe. We found that t-FeTe presented a pressure-induced transition from an antiferromagnetic state to a ferromagnetic state at ∼3 GPa, corresponding to the tetragonal collapse of the layered structure. Contrarily, the ferromagnetic order of h-FeTe was retained up to 15 GPa, which was evidently confirmed by electrical transport and Raman measurements. Furthermore, T-P phase diagrams for t-FeTe and h-FeTe were mapped under delicate critical conditions. Our results can provide a unique platform to elaborate the extraordinary properties of Fe chalcogenides and further develop their applications.

Coexistence of Ferroelectricity and Ferromagnetism in Atomically Thin Two-Dimensional Cr2S3/WS2 Vertical Heterostructures.

Two-dimensional (2D) heterostructures with ferromagnetism and ferroelectricity provide a promising avenue to miniaturize the device size, increase computational power, and reduce energy consumption. However, the direct synthesis of such eye-catching heterostructures has yet to be realized up to now. Here, we design a two-step chemical vapor deposition strategy to growth of Cr2S3/WS2 vertical heterostructures with atomically sharp and clean interfaces on sapphire. The interlayer charge transfer and periodic moiré superlattice result in the emergence of room-temperature ferroelectricity in atomically thin Cr2S3/WS2 vertical heterostructures. In parallel, long-range ferromagnetic order is discovered in 2D Cr2S3 via the magneto-optical Kerr effect technique with the Curie temperature approaching 170 K. The charge distribution variation induced by the moiré superlattice changes the ferromagnetic coupling strength and enhances the Curie temperature. The coexistence of ferroelectricity and ferromagnetism in 2D Cr2S3/WS2 vertical heterostructures provides a cornerstone for the further design of logic-in-memory devices to build new computing architectures.

Interisland-Distance-Mediated Growth of Centimeter-Scale Two-Dimensional Magnetic Fe3O4 Arrays with Unidirectional Domain Orientations.

Two-dimensional (2D) nanosheet arrays with unidirectional orientations are of great significance for synthesizing wafer-scale single crystals. Although great efforts have been devoted, the growth of atomically thin magnetic nanosheet arrays and single crystals is still unaddressed. Here we design an interisland-distance-mediated chemical vapor deposition strategy to synthesize centimeter-scale atomically thin Fe3O4 arrays with unidirectional orientations on mica. The unidirectional alignment of nearly all the Fe3O4 nanosheets is driven by a dual-coupling-guided growth mechanism. The Fe3O4/mica interlayer interaction induces two preferred antiparallel orientations, whereas the interisland interaction of Fe3O4 breaks the energy degeneracy of antiparallel orientations. The room-temperature long-range ferrimagnetic order and thickness-tunable magnetic domain evolution are uncovered in atomically thin Fe3O4. This strategy to tune the orientations of nanosheets through the an interisland interaction can guide the synthesis of other 2D transition-metal oxides, thereby laying a solid foundation for future spintronic device applications at the integration level.

Phase-Modulated Elastic Properties of 2D Magnetic FeTe: Hexagonal and Tetragonal Polymorphs.

2D layered magnets, such as iron chalcogenides, have emerged these years as a new family of unconventional superconductors and provided the key insights to understand the phonon-electron interaction and pairing mechanism. Their mechanical properties are of strategic importance for the potential applications in spintronics and optoelectronics. However, there is still a lack of efficient approach to tune the elastic modulus despite the extensive studies. Herein, the modulated elastic modulus of 2D magnetic FeTe and its thickness-dependence is reported via phase engineering. The grown 2D FeTe by chemical vapor deposition can present various polymorphs, that is tetragonal FeTe (t-FeTe, antiferromagnetic) and hexagonal FeTe (h-FeTe, ferromagnetic). The measured Young's modulus of t-FeTe by nanoindentation method shows an obvious thickness-dependence, from 290.9 ± 9.2 to 113.0 ± 8.7 GPa when the thicknesses increased from 13.2 to 42.5 nm, respectively. In comparison, the elastic modulus of h-FeTe remains unchanged. These results can shed light on the efficient modulation of mechanical properties of 2D magnetic materials and pave the avenues for their practical applications in nanodevices.

FeN Coordination Induced Ultralong Lifetime of Sodium-Ion Battery with the Cycle Number Exceeding 65 000.

Sodium-ion batteries (SIBs) have received increasing attention because of their appealing cell voltages and cost-effective features. However, the atom aggregation and electrode volume variation inevitably deteriorate the sodium storage kinetics. Here a new strategy is proposed to boost the lifetime of SIB by synthesizing sea urchin-like FeSe2 /nitrogen-doped carbon (FeSe2 /NC) composites. The robust FeN coordination hinders the Fe atom aggregation and accommodates the volume expansion, while the unique biomorphic morphology and high conductivity of FeSe2 /NC enhance the intercalation/deintercalation kinetics and shorten the ion/electron diffusion length. As expected, FeSe2 /NC electrodes deliver excellent half (387.6 mAh g-1 at 20.0 A g-1 after 56 000 cycles) and full (203.5 mAh g-1 at 1.0 A g-1 after 1200 cycles) cell performances. Impressively, an ultralong lifetime of SIB composed of FeSe2 /Fe3 Se4 /NC anode is uncovered with the cycle number exceeding 65 000. The sodium storage mechanism is clarified with the aid of density function theory calculations and in situ characterizations. This work hereby provides a new paradigm for enhancing the lifetime of SIB by constructing a unique coordination environment between active material and framework.

The catalytic mechanism of direction-dependent interactions for 2,3-dihydroxybenzoate decarboxylase.

Benzoic acid decarboxylases offer an elegant alternative to CO2 fixation by reverse reaction-carboxylation, which is named the bio-Kolbe-Schmitt reaction, but they are unfavorable to carboxylation. Enhancing the carboxylation efficiency of reversible benzoic acid decarboxylases is restricted by the unexplained carboxylation mechanisms. The direction of reversible enzyme catalytic reactions depends on whether catalytic residues at the active center of the enzyme are protonated, which is subjected by the pH. Therefore, the forward and reverse reactions could be separated at different pH values. Reversible 2,3-dihydroxybenzoate acid decarboxylase undergoes decarboxylation at pH 5.0 and carboxylation at pH 8.6. However, it is unknown whether the interaction of enzymes with substrates and products in the forward and reverse reactions can be exploited to improve the catalytic activity of reversible enzymes in the unfavorable direction. Here, we identify a V-shaped tunnel of 2,3-dihydroxybenzoic acid decarboxylase from Aspergillus oryzae (2,3-DHBD_Ao) through which the substrate travels in the enzyme, and demonstrate that the side chain conformation of a tyrosine residue controls the entry and exit of substrate/product during reversible reactions. Together with the kinetic studies of the mutants, it is clarified that interactions between substrate/product traveling through the enzyme tunnel in 2,3-DHBD_Ao are direction-dependent. These results enrich the understanding of the interactions of substrates/products with macromolecular reversible enzymes in different reaction directions, thereby demonstrating a possible path for engineering decarboxylases with higher carboxylation efficiency. KEY POINTS: • The residue Trp23 of 2,3-DHBD_Ao served as a switch to control the entry and exit of catechol • A V-shaped tunnel of 2,3-DHBD_Ao for decarboxylation and carboxylation reactions was identified • The results provide a promising strategy for engineering decarboxylases with direction-dependent residues inside the substrate/product traveling tunnel of the enzyme.

BMEFIQA: Blind Quality Assessment of Multi-Exposure Fused Images Based on Several Characteristics.

A multi-exposure fused (MEF) image is generated by multiple images with different exposure levels, but the transformation process will inevitably introduce various distortions. Therefore, it is worth discussing how to evaluate the visual quality of MEF images. This paper proposes a new blind quality assessment method for MEF images by considering their characteristics, and it is dubbed as BMEFIQA. More specifically, multiple features that represent different image attributes are extracted to perceive the various distortions of MEF images. Among them, structural, naturalness, and colorfulness features are utilized to describe the phenomena of structure destruction, unnatural presentation, and color distortion, respectively. All the captured features constitute a final feature vector for quality regression via random forest. Experimental results on a publicly available database show the superiority of the proposed BMEFIQA method to several blind quality assessment methods.

Resveratrol promotes skin wound healing by regulating the miR-212/CASP8 axis.

The wound-healing process is a natural response to burn injury. Resveratrol (RES) may have potential as a therapy for wound healing, but how and whether RES regulates skin repair remains poorly understood. Human epidermal keratinocyte (HaCaT) cells were treated with lipopolysaccharide (LPS), and a mouse skin wound-healing model was established. Cell viability and apoptosis were analyzed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide or flow cytometry. Cell proliferation was assessed by cell viability and colony-formation analyses. Cell migration was tested by wound-healing analysis. The microRNA-212 (miR-212) and caspase-8 (CASP8) levels were determined by quantitative reverse transcription polymerase chain reaction and western blotting. The correlation between miR-212 and CASP8 was analyzed by dual-luciferase reporter analysis. Skin wound healing in mice was assessed by measuring the wound area and gap after hematoxylin-eosin (HE) staining. RES reduced the LPS-induced reduction in viability and apoptosis in HaCaT cells. miR-212 expression was reduced by LPS and increased by exposure to RES. RES promoted cell proliferation and migration after LPS treatment by increasing miR-212 levels. CASP8 was a target of miR-212. CASP8 silencing promoted cell proliferation and migration, which was reversed by miR-212 knockdown in LPS-treated HaCaT cells. RES promoted skin wound healing in mice, which was reduced by miR-212 knockdown. Thus, RES facilitates cell proliferation and migration in LPS-treated HaCaT cells and promotes skin wound-healing in a mouse model by regulating the miR-212/CASP8 axis.

High-Q quadrupolar plasmonic lattice resonances in horizontal metal-insulator-metal gratings.

We propose a plasmonic platform for achieving out-of-plane quadrupolar plasmonic surface lattice resonances (SLRs) with large quality factors. The proposed platform is composed of a horizontal metal-insulator-metal (MIM) grating embedded in a homogeneous dielectric environment. Numerical results based on rigorous coupled-wave analysis show that under oblique incidences, high-Q out-of-plane quadrupolar SLRs can be excited at wavelengths of 1242 nm over a wide range of insulator widths, and the quality factor can reach 1036. As a comparison, under the same conditions, only dipolar SLRs with much lower quality factors of ∼300 can be excited in a vertical MIM grating, which has the same period and a quarter-turned unit cell. We expect that the proposed high-Q quadrupolar SLR platform will find applications in light-matter interactions on the nanoscale.

Correction to: Identification of ALDH3A2 as a novel prognostic biomarker in gastric adenocarcinoma using integrated bioinformatics analysis.

An amendment to this paper has been published and can be accessed via the original article.

Identification of ALDH3A2 as a novel prognostic biomarker in gastric adenocarcinoma using integrated bioinformatics analysis.

BACKGROUND: Extensive research has revealed that genes play a pivotal role in tumor development and growth. However, the underlying involvement of gene expression in gastric carcinoma (GC) remains to be investigated further. METHODS: In this study, we identified overlapping differentially expressed genes (DEGs) by comparing tumor tissue with adjacent normal tissue using the Gene Expression Omnibus (GEO) and the Cancer Genome Atlas (TCGA) database. RESULTS: Our analysis identified 79 up-regulated and ten down-regulated genes. Functional enrichment analysis and prognosis analysis were conducted on the identified genes, and the fatty aldehyde dehydrogenase (FALDH) gene, ALDH3A2, was chosen for more detailed analysis. We performed Gene Set Enrichment Analysis (GSEA) and immunocorrelation analysis (infiltration, copy number alterations, and checkpoints) to elucidate the mechanisms of action of ALDH3A2 in depth. The immunohistochemical (IHC) result based on 140 paraffin-embedded human GC samples indicated that ALDH3A2 was over-expressed in low-grade GC cases and the OS of patients with low expression of ALDH3A2 was significantly shorter than those with high ALDH3A2 expression. In vitro results indicated that the expression of ALDH3A2 was negatively correlated with PDCD1, PDCD1LG2, and CTLA-4. CONCLUSION: We conclude that ALDH3A2 might be useful as a potential reference value for the relief and immunotherapy of GC, and also as an independent predictive marker for the prognosis of GC.

Active smoking, sleep quality and cerebrospinal fluid biomarkers of neuroinflammation.

BACKGROUNDS: Cigarette smoking has been shown to be associated with sleep disorders and the related neuropathogenesis including neuroinflammation. Previous studies showed that pro- and anti-inflammatory cytokines are physiologically important in maintaining circadian function. In addition, sleep deprivation leads to immune dysregulations. However, no study has been published yet by using cerebrospinal fluid (CSF) biomarkers of neuroinflammation to investigate the relationship between active cigarette smoking and sleep disorders. METHODS: CSF tissues from subjects of 191 male subjects (non-smokers n = 104; active smokers n = 87) receiving local anesthesia before surgery for anterior cruciate ligament injuries were obtained after the assessment of clinical information and Pittsburgh Sleep Quality Index (PSQI). The levels of tumor necrosis factor alpha (TNFα), Interleukin (IL) 1 beta (IL1ß), IL2, IL4, IL6 and IL10 were measured using radioimmunoassay and ELISA. RESULTS: PSQI scores were significantly higher in active smokers than that in non-smokers (p < 0.001, Cohen's d = 0.63). Significantly higher levels of CSF TNFα were found in active smokers compared to non-smokers (28 ± 1.97 vs. 22.97 ± 2.48, p < 0.05, Cohen's d = 2.23). There was a positive correlation between CSF IL1ß levels and PSQI scores in non-smokers (r = 0.31, p = 0.01, adjustment R-Squared = 0.11). DISCUSSION: This is the first study to reveal the association between higher CSF TNFα levels and poorer sleep quality in active smoking. In addition, CSF IL1ß levels might be a potential biomarker in central nervous system for circadian dysregulation.

Knockdown of ghrelin-O-acyltransferase attenuates colitis through the modulation of inflammatory factors and tight junction proteins in the intestinal epithelium.

Ghrelin-O-acyltransferase (GOAT) is a membrane-bound enzyme that attaches eight-carbon octanoate to a serine residue in ghrelin and thereby acylates inactive ghrelin to produce active ghrelin. In this study, we investigated the function of GOAT in the intestinal mucosal barrier. The intestinal mucosal barrier prevents harmful substances such as bacteria and endotoxin from entering the other tissues, organs, and blood circulation through the intestinal mucosa. Here, we established 5% dextran sodium sulfate (DSS)-induced colitis in mice and found that the body weight and colon weight were significantly decreased in these mice. Furthermore, increased inflammation and apoptosis were observed in the tissues of DSS-induced colitis mice, with increased expression of tumor necrosis factor-α, interleukin-6, phosphorylation of nuclear factor kappa B-p65 (p-NF-κB-p65), and cleaved caspase-3, and decreased expression of tight junction (TJ) proteins such as zonula occluden-1 and occludin. The knockdown of GOAT significantly attenuated colitis-induced inflammation responses and apoptosis, while GOAT overexpression significantly enhanced the induction of colitis. These results suggest that knockdown of GOAT may attenuate colitis-induced inflammation, ulcers, and fecal occult blood by decreasing the intestinal mucosal permeability via the modulation of inflammatory factors and TJ proteins.

Improved SERS activity of non-stoichiometric copper sulfide nanostructures related to charge-transfer resonance.

The low enhancement factor of semiconductor SERS substrates is a major obstacle for their practical application. Therefore, there is a need to explore the facile synthesis of new SERS substrates and reveal the SERS enhancement mechanism. Here, we develop a simple, facile and low-cost two-step method to synthesize copper sulfide based nanostructures with different Cu7.2S4 contents. The as-synthesized sample is composed of nanosheets with the CuS phase structure. With the increase of the annealing temperature to 300 °C, the CuS content gradually decreases and disappears, and the content of Cu7.2S4 and CuSO4 appears and gradually increases. At the annealing temperature of 350 °C, only CuSO4 exists. Compared with pure CuS or pure CuSO4, the detection limit of R6G molecules is the lowest for the composite sample with a higher content of Cu7.2S4, indicating that the introduction of non-stoichiometric Cu7.2S4 can improve the SERS performance and the higher content of Cu7.2S4 leads to a higher SERS activity. Furthermore, to investigate the SERS mechanism, the energy band structures and energy-level diagrams of different probe molecules over CuS, Cu7.2S4 and CuxS are studied by DFT calculations. Theoretical calculations indicate that the excellent SERS behavior depends on charge transfer resonance. Our work provides a general approach for the construction of excellent metal compound semiconductor SERS active substrates.

Efficient planar plasmonic directional launching of linearly polarized light in a catenary metasurface.

Efficient directional excitation of planar surface plasmon polaritons (SPPs) has important and wide applications in micro-nano photonic technology. Recently, by using the geometric phase and spin-orbit interaction, catenary structures have been applied to the directional control of SPPs and showed excellent performance. However, due to the need to use the chirality of the subwavelength catenary apertures, the previously studied systems were only suitable for circularly polarized light. Here, based on a catenary metasurface we theoretically design and experimentally demonstrate a SPP directional launcher used for linearly polarized light. The numerical calculation results show that the directional extinction ratio reaches up to 35 dB under the normal incidence of p-polarized light at 750 nm which is 5 dB higher than the maximum extinction ratio in the existing results as we know. The experimental results show that the resonant wavelength position, bandwidth and extinction ratio change trend well match the theoretical results. The physical mechanism is analyzed and it is found that the asymmetric quadrupole mode is the key factor leading to the directional SPPs which is completely different from the geometric phase modulation mechanism to excite the directional SPPs of circularly polarized light in the catenary metasurface. These principles and methods could open new doors for future chip-level photonic device or system design such as multi-directional beam splitters and polarization detectors.

Scalable Production of Two-Dimensional Metallic Transition Metal Dichalcogenide Nanosheet Powders Using NaCl Templates toward Electrocatalytic Applications.

Two-dimensional (2D) metallic transition metal dichalcogenides (MTMDCs) have attracted tremendous interest due to their intriguing physical properties and broad application potential. However, batch production of high-quality 2D MTMDCs based on existing synthesis on 2D surfaces remains a huge challenge. Herein, a universal synthetic route for the scalable synthesis of high-quality 2D MTMDC (e.g., TaS2, V5S8, and NbS2) nanosheets using microcrystalline NaCl crystals as templates via a facile chemical vapor deposition method is reported. Obviously, this synthetic route is perfectly compatible with a facile water dissolution-filtration process for obtaining high-purity MTMDC nanosheet powders. Representatively, a thickness-uniform 1T-TaS2 nanosheet product can be achieved that shows unexceptionable dispersibility in ethanol, which allows its assembly onto arbitrary substrates/electrodes for high-performance energy-related applications, herein serving as a high-performance electrocatalyst for the hydrogen evolution reaction. This work sheds light on the batch production, green transfer, and energy-related application of 2D MTMDC materials.

Design and biomechanical characteristics of porous meniscal implant structures using triply periodic minimal surfaces.

BACKGROUND: Artificial meniscal implants can be used to replace a severely injured meniscus after meniscectomy and restore the normal functionality of a knee joint. The aim of this paper was to design porous meniscal implants and assess their biomechanical properties. METHODS: Finite element simulations were conducted on eight different cases including intact healthy knees, knee joints with solid meniscal implants, and knee joints with meniscal implants with two types of triply periodic minimal surfaces. Compression stresses, shear stresses, and characteristics of stress concentrated areas were evaluated using an axial compressive load of 1150 N and an anterior load of 350 N. RESULTS: Compared to the solid meniscal implant, the proposed porous meniscal implant produced lower levels of compression and shear stresses on the cartilage, which facilitated the cartilage to retain a semilunar characteristic similar to the natural meniscus. Moreover, both compression and shear stresses on the artificial cartilage were found to be sensitive to the pore properties of the meniscal implant. The meniscal implants with primitive surfaces (porosity: 41%) showed a better performance in disseminating stresses within the knee joint. CONCLUSION: The present commercial meniscal implant has the problem of equivalent biomechanical properties compared to natural menisci. The main advantage of the proposed porous structure is that it can be used to prevent excessive compression and shear stresses on the articular cartilages. This structure has advantages both in terms of mechanics and printability, which can be beneficial for future clinical applications.

Recent advances in microfluidic cell sorting techniques based on both physical and biochemical principles.

Microfluidic technologies for isolating cells of interest from a heterogeneous sample have attracted great attentions, due to the advantages of less sample consumption, simple operating procedure, and high separation accuracy. According to the working principles, the microfluidic cell sorting techniques can be categorized into biochemical (labeled) and physical (label-free) methods. However, the inherent drawbacks of each type of method may somehow influence the popularization of these cell sorting techniques. Using the multiple complementary isolation principles is a promising strategy to overcome this problem, therefore there appears to be a continuing trend to integrate two or more sorting methods together. In this review, we focus on the recent advances in microfluidic cell sorting techniques relied on both physical and biochemical principles, with emphasis on the mechanisms of cell separation. The biochemical cell sorting techniques enhanced by physical principles and the physical cell sorting techniques enhanced by biochemical principles, are first introduced. Then, we highlight on-chip magnetic-activated cell sorting, on-chip fluorescence-activated cell sorting, multi-step cell sorting and multi-principle cell sorting techniques, which are based on both physical and biochemical separation mechanisms. Finally, the challenges and future perspectives of the integrated microfluidics for cell sorting are discussed.

Na-assisted fast growth of large single-crystal MoS2 on sapphire.

Monolayer molybdenum sulfide (MoS2), a typical semiconducting transition metal dichalcogenide, has emerged as a perfect platform for next-generation electronics and optoelectronics due to its sizeable band gap and strong light-matter interactions. Nevertheless, the controlled growth of a monolayer MoS2 single-crystal with a large-domain size and high crystal quality still faces great challenges. Herein, we demonstrate the fast growth of a large-domain monolayer MoS2 on the c-plane sapphire substrate with the assistance of sodium chloride (NaCl) crystals as the intermediate promoter. Particularly, the volatilization temperature of the NaCl crystal and the growth temperature of MoS2 are established to be the key parameters that influence the growth efficiency of MoS2 at an optimized growth condition. Monolayer triangular MoS2 domain with an edge length ∼300 µm is obtained within 1 min, featured with a growth rate ∼5 µm s-1. The Na element from the NaCl crystal is found to be able to facilitate the two dimensional growth of monolayer MoS2. This work thus offers novel insights into the high-efficiency production of large-domain monolayer MoS2 on insulating growth substrates.

Recent progress in the controlled synthesis of 2D metallic transition metal dichalcogenides.

Two-dimensional (2D) metallic transition metal dichalcogenides (MTMDCs), the complement of 2D semiconducting TMDCs, have attracted extensive attentions in recent years because of their versatile properties such as superconductivity, charge density wave, and magnetism. To promote the investigations of their fantastic properties and broad applications, the preparation of large-area, high-quality, and thickness-tunable 2D MTMDCs has become a very urgent topic and great efforts have been made. This topical review therefore focuses on the introduction of the recent achievements for the controllable syntheses of 2D MTMDCs (VS2, VSe2, TaS2, TaSe2, NbS2, NbSe2, etc). To begin with, some earlier developed routes such as chemical vapor transport, mechanical/chemical exfoliation, as well as molecular beam epitaxy methods are briefly introduced. Secondly, the scalable chemical vapor deposition methods involved with two sorts of metal-based feedstocks, including transition metal chlorides and transition metal oxidations mixed with alkali halides, are discussed separately. Finally, challenges for the syntheses of high-quality 2D MTMDCs are discussed and the future research directions in the related fields are proposed.