Ultrahard bulk amorphous carbon from collapsed fullerene.

Amorphous materials inherit short- and medium-range order from the corresponding crystal and thus preserve some of its properties while still exhibiting novel properties1,2. Due to its important applications in technology, amorphous carbon with sp2 or mixed sp2-sp3 hybridization has been explored and prepared3,4, but synthesis of bulk amorphous carbon with sp3 concentration close to 100% remains a challenge. Such materials inherit the short-/medium-range order of diamond and should also inherit its superior properties5. Here, we successfully synthesized millimetre-sized samples-with volumes 103-104 times as large as produced in earlier studies-of transparent, nearly pure sp3 amorphous carbon by heating fullerenes at pressures close to the cage collapse boundary. The material synthesized consists of many randomly oriented clusters with diamond-like short-/medium-range order and possesses the highest hardness (101.9 ± 2.3 GPa), elastic modulus (1,182 ± 40 GPa) and thermal conductivity (26.0 ± 1.3 W m-1 K-1) observed in any known amorphous material. It also exhibits optical bandgaps tunable from 1.85 eV to 2.79 eV. These discoveries contribute to our knowledge about advanced amorphous materials and the synthesis of bulk amorphous materials by high-pressure and high-temperature techniques and may enable new applications for amorphous solids.

Centimeter-sized diamond composites with high electrical conductivity and hardness.

Achieving high-performance materials with superior mechanical properties and electrical conductivity, especially in large-sized bulk forms, has always been the goal. However, it remains a grand challenge due to the inherent trade-off between these properties. Herein, by employing nanodiamonds as precursors, centimeter-sized diamond/graphene composites were synthesized under moderate pressure and temperature conditions (12 GPa and 1,300 to 1,500 °C), and the composites consisted of ultrafine diamond grains and few-layer graphene domains interconnected through covalently bonded interfaces. The composites exhibit a remarkable electrical conductivity of 2.0 × 104 S m-1 at room temperature, a Vickers hardness of up to ~55.8 GPa, and a toughness of 10.8 to 19.8 MPa m1/2. Theoretical calculations indicate that the transformation energy barrier for the graphitization of diamond surface is lower than that for diamond growth directly from conventional sp2 carbon materials, allowing the synthesis of such diamond composites under mild conditions. The above results pave the way for realizing large-sized diamond-based materials with ultrahigh electrical conductivity and superior mechanical properties simultaneously under moderate synthesis conditions, which will facilitate their large-scale applications in a variety of fields.

Tuning the Flat Band in Bi2O2Se by Pressure to Induce Superconductivity.

The discovery of superconductivity in twisted bilayer graphene has reignited enthusiasm in the field of flat-band superconductivity. However, important challenges remain, such as constructing a flat-band structure and inducing a superconducting state in materials. Here, we successfully achieved superconductivity in Bi2O2Se by pressure-tuning the flat-band electronic structure. Experimental measurements combined with theoretical calculations reveal that the occurrence of pressure-induced superconductivity at 30 GPa is associated with a flat-band electronic structure near the Fermi level. Moreover, in Bi2O2Se, a van Hove singularity is observed at the Fermi level alongside pronounced Fermi surface nesting. These remarkable features play a crucial role in promoting strong electron-phonon interactions, thus potentially enhancing the superconducting properties of the material. These findings demonstrate that pressure offers a potential experimental strategy for precisely tuning the flat band and achieving superconductivity.

Biomimetic NO Scavenging Hyaluronic Acid Nanoparticles Enable Targeted Delivery of MTX and Integrated Management of Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a complicated chronic disorder of the immune system, featured with severe inflammatory joints, synovium hyperplasia, articular cartilage, and bone damage. In the RA microenvironment, RA-involved cells, overproduced nitric oxide (NO), and pro-inflammatory cytokines are highly interplayed and mutually reinforced, which form a vicious circle and play crucial roles in the formation and progression of RA. To comprehensively break the vicious circle and obtain the maximum benefits, we have developed neutrophil membrane-camouflaged NO scavenging nanoparticles based on an NO-responsive hyaluronic acid derivative for delivery of MTX. These multifunctional nanoparticles (NNO-NPs/MTX), by inheriting the membrane functions of the source cells, possess prolonged circulation and specific localization at the inflamed sites when administrated in the body. Remarkably, NNO-NPs/MTX can neutralize the pro-inflammatory cytokines via the outer membrane receptors, scavenge NO, and be responsively disassociated to release MTX for RA-involved cell regulation and HA for lubrication in the RA sites. In a collagen-induced arthritis mouse model, NNO-NPs/MTX exhibits a significant anti-inflammation effect and effectively alleviates the characteristic RA symptoms such as synovial hyperplasia and cartilage destruction, realizing the synergistic and boosted therapeutic outcome against intractable RA. Thus, NNO-NPs/MTX provides a promising and potent platform to integrately treat RA.

Ambient-Condition Recoverable Polymeric N10 Discovered from the Predicted Zr-N Compounds.

Polynitrogen has been widely studied recently as a rising star of high energy density materials. Here, we performed a systematic study of the Zr-N compounds in the N-rich region by the first-principles method. The high-pressure phase diagram of the Zr-N system is enriched by proposing five new compounds. ZrN10 with the infinitely extended band shaped structure is first reported. The band-like polynitrogen of ZrN10 decomposes into a more stable chain-like polynitrogen structure under the influence of temperature. Additionally, the novel honeycomb-like band-shaped N10 structure hcb-N10 has been discovered by removing the Zr atoms. The absence of the -4 oxidation state in the N10 unit prompts its further polymerization, which makes hcb-N10 possess dynamical and thermal stability in ambient conditions. hcb-N10 is a semiconductor with a bandgap of 2.97 eV due to highly localized electrons. Both chain-ZrN10 and hcb-N10 represent potential candidates for HEDMs with outstanding energy and explosive performance.

Anomalous Pressure Response of Temperature-Induced Spin Transition and a Pressure-Induced Spin Transition in Two-Dimensional Hofmann Coordination Polymers.

Spin transition (ST) compounds have been extensively studied because of the changes in rich physicochemical properties accompanying the ST process. The study of ST mainly focuses on the temperature-induced spin transition (TIST). To further understand the ST, we explore the pressure response behavior of TIST and pressure-induced spin transition (PIST) of the 2D Hofmann-type ST compounds [Fe(Isoq)2M(CN)4] (Isoq-M) (M = Pt, Pd, Isoq = isoquinoline). The TISTs of both Isoq-Pt and Isoq-Pd compounds exhibit anomalous pressure response, where the transition temperature (T1/2) exhibits a nonlinear pressure dependence and the hysteresis width (ΔT1/2) exhibits a nonmonotonic behavior with pressure, by the synergistic influence of the intermolecular interaction and the distortion of the octahedral coordination environment. And the distortion of the octahedra under critical pressures may be the common behavior of 2D Hofmann-type ST compounds. Moreover, ΔT1/2 is increased compared with that before compression because of the partial irreversibility of structural distortion after decompression. At room temperature, both compounds exhibit completely reversible PIST. Because of the greater change in mechanical properties before and after ST, Isoq-Pt exhibits a more abrupt ST than Isoq-Pd. In addition, it is found that the hydrostatic properties of the pressure transfer medium (PTM) significantly affect the PIST due to their influence on spin-domain formation.

Up-regulation of Dsg2 confered stem cells with malignancy through wnt/ß-catenin signaling pathway.

In the previous study, we originally developed cancer stem cells (CSCs) models from mouse induced pluripotent stem cells (miPSCs) by culturing miPSCs in the conditioned medium of cancer cell lines, which mimiced as carcinoma microenvironment. However, the molecular mechanism of conversion in detail remains to be uncovered. Microarray analysis of the CSCs models in this study revealed Dsg2, one of the members of the desmosomal cadherin family, was up-regulated when compared with the original miPSCs. Moreover, the expression of key factors in Wnt/ß-catenin signaling pathway were also found up-regulated in one of the CSCs models, named miPS-LLCcm. An autocrine loop was implied between Dsg2 and Wnt/ß-catenin signaling pathway when miPSCs were treated with Wnt/ß-catenin signaling pathway activators, Wnt3a and CHIR99021, and when the CSCs model were treated with inhibitors, IWR-1 and IWP-2. Furthermore, the ability of proliferation and self-renewal in the CSCs model was markedly decreased in vitro and in vivo when Dsg2 gene was knocked down by shRNA. Our results showed that the Wnt/ß-catenin signaling pathway is activated by the up-regulation of Dsg2 expresssion during the conversion of miPSCs into CSCs implying a potential mechanism of the tranformation of stem cells into malignant phenotype.

Rapid detection and quantification of adulteration in saffron by excitation-emission matrix fluorescence combined with multi-way chemometrics.

BACKGROUND: Saffron has gained people's attention and love for its unique flavor and valuable edible value, but the problem of saffron adulteration in the market is serious. It is urgent for us to find a simple and rapid identification and quantitative estimation of adulteration in saffron. Therefore, excitation-emission matrix (EEM) fluorescence combined with multi-way chemometrics was proposed for the detection and quantification of adulteration in saffron. RESULTS: The fluorescence composition analysis of saffron and saffron adulterants (safflower, marigold and madder) were accomplished by alternating trilinear decomposition (ATLD) algorithm. ATLD and two-dimensional principal component analysis combined with k-nearest neighbor (ATLD-kNN and 2DPCA-kNN) and ATLD combined with data-driven soft independent modeling of class analogies (ATLD-DD-SIMCA) were applied to rapid detection of adulteration in saffron. 2DPCA-kNN and ATLD-DD-SIMCA methods were adopted for the classification of chemical EEM data, first with 100% correct classification rate. The content of adulteration of adulterated saffron was predicted by the N-way partial least squares regression (N-PLS) algorithm. In addition, new samples were correctly classified and the adulteration level in adulterated saffron was estimated semi-quantitatively, which verifies the reliability of these models. CONCLUSION: ATLD-DD-SIMCA and 2DPCA-kNN are recommended methods for the classification of pure saffron and adulterated saffron. The N-PLS algorithm shows potential in prediction of adulteration levels. These methods are expected to solve more complex problems in food authenticity. © 2023 Society of Chemical Industry.

Abnormal Metal-Semiconductor-Like Transition and Exceptional Enhanced Superconducting State in Pressurized Restacked TaS2.

Interlayer coupling and stacking order play essential roles in shaping the exotic electronic properties of two-dimensional materials. Here, we employ restacked TaS2─a novel transition metal dichalcogenide (TMD) with weak vdW bonding and twisted angles─to investigate the strain effects of interlayer modulation on the electronic properties. Under pressure, an unexpected transition from metallic to semiconducting-like states occurs. Superconductivity coexists with the semiconducting-like state over a wide pressure range, which has never before been observed in TMDs. Upon further compression, a new superconducting SC-II state emerges without structural evolution and gradually replaces the initial SC-I state. The emerging SC-II state exhibits robust zero-resistance superconductivity and an ultrahigh upper critical field. The abundant electronic state changes in RS-TaS2 are strongly related to band-structure engineering resulting from pressure-induced interlayer stacking angle modulation. Our results reveal the remarkable effect of interlayer rearrangement on electronic properties and provide a special way to explore the unique properties of 2D materials.

Optical perfectly matched layers based on the integration of photonic crystals and material loss.

Perfectly matched layer (PML) is a virtual absorption boundary condition adopted in numerical simulations, capable of absorbing light from all incident angles, which however is still lacking in practice in the optical regime. In this work, by integrating dielectric photonic crystals and material loss, we demonstrate an optical PML design with near-omnidirectional impedance matching and customized bandwidth. The absorption efficiency exceeds 90% for incident angle up to 80°. Good consistence is found between our simulations and proof-of-principle microwave experiments. Our proposal paves the road to realize optical PMLs, and could find applications in future photonic chips.

Two Ultrahigh-Energy-Density Layered Cerium Polynitrides with Molecular Sieve Channel.

Two high-pressure stable phases (I41/a-CeN4 and R3̅m-CeN6) and two metastable phases (P6mm-CeN14 and P6mm-CeN17) were proposed in Ce-N compounds at 150-300 GPa. The polymeric nitrogen units include quadruple helical chains, N6 rings, and first reported layered molecular sieves structures. I41/a-CeN4 can be quenched to ambient conditions and its thermal stability can be maintained up to 500 K. P6mm-CeN14 is dynamically and mechanically stable at ambient pressure. The electronic properties analyses show that charge transfer between the Ce and N atoms makes a significant contribution to the structural stability by promoting the formation of Ce-N ionic bond and N-N covalent bond. The Ce atom provides a suitable coordination environment and an excellent bonding state for the fully sp3 hybridized layered molecular sieve to enhance the stability of P6mm-CeN14. Surprisingly, the energy density (8.45 kJ/g) and explosive performance of P6mm-CeN14 are the highest among all metal polynitrides, refreshing a new record for high-energy metal polynitrides.

CaCO3 powder-mediated biomineralization of antigen nanosponges synergize with PD-1 blockade to potentiate anti-tumor immunity.

Antigen self-assembly nanovaccines advance the minimalist design of therapeutic cancer vaccines, but the issue of inefficient cross-presentation has not yet been fully addressed. Herein, we report a unique approach by combining the concepts of "antigen multi-copy display" and "calcium carbonate (CaCO3) biomineralization" to increase cross-presentation. Based on this strategy, we successfully construct sub-100 nm biomineralized antigen nanosponges (BANSs) with high CaCO3 loading (38.13 wt%) and antigen density (61.87%). BANSs can be effectively uptaken by immature antigen-presenting cells (APCs) in the lymph node upon subcutaneous injection. Achieving efficient spatiotemporal coordination of antigen cross-presentation and immune effects, BANSs induce the production of CD4+ T helper cells and cytotoxic T lymphocytes, resulting in effective tumor growth inhibition. BANSs combined with anti-PD-1 antibodies synergistically enhance anti-tumor immunity and reverse the tumor immunosuppressive microenvironment. Overall, this CaCO3 powder-mediated biomineralization of antigen nanosponges offer a robust and safe strategy for cancer immunotherapy.

Danggui-Buxue decoction alleviated vascular senescence in mice exposed to chronic intermittent hypoxia through activating the Nrf2/HO-1 pathway.

CONTEXT: As a major risk factor for cardiovascular diseases (CVD), Obstructive sleep apnea (OSA) is characterized by chronic intermittent hypoxia (CIH). Recent studies indicated that the increased cardiovascular risk in patients with OSA may be mediated by accelerated vascular senescence. Danggui-Buxue decoction (DBD) has been used for treating cardiovascular diseases, but its mechanism of vascular senescence regulation is still unclear. OBJECTIVE: To investigate the effect of DBD on vascular senescence in mice exposed to CIH and to explore the role of the Nrf2/HO-1 pathway. MATERIALS AND METHODS: C57BL/6N mice were randomly divided into Normoxia control group (CON), CIH (21%-5% O2, 20 times/h, 8 h/d) exposed group (CIH), and DBD treatment group (intragastrically treated with 2.34, 4.68, or 9.36 g/kg/day of DBD separately for 12 weeks as DBL, DBM, or DBH). Blood pressure, cardiac and vascular function, vascular senescence, inflammation response, oxidative stress, and Nrf2/HO-1 expression were determined. RESULTS: DBD (4.68 and 9.36 g/kg) significantly decreased Tail-cuff blood pressure, increased left ventricular systolic function, and alleviated arterial stiffness and vasorelaxation dysfunction in mice exposed to CIH. DBD treatment reduced SA-ß-gal activity, decreased p16 (0.68-fold, 0.62-fold), P21 (0.58-fold, 0.52-fold), and p53 expressions (0.67-fold, 0.65-fold), and increased SIRT1 expression (2.22-fold, 2.98-fold) in the aortic. DBD treatment decreased IL-6, NF-κB, and TNF-α expressions, decreased MDA but increased SOD levels, and increased Nrf2 (1.8-fold, 1.89-fold) and HO-1 (2.25-fold, 2.43-fold) expression. DISCUSSION AND CONCLUSIONS: DBD could attenuate vascular senescence accelerated by CIH exposure through inhibiting inflammatory response and oxidative stress by activating the Nrf2/HO-1 pathway.

Dynamic Hydrogen-Bond Network as a Modulator of Bismuth-Antimony Complex Anodes for Self-Healable and Wider Temperature Adaptive Potassium Ion Batteries.

Antimony (Sb)-based anodes are attractive candidates in potassium-ion batteries (PIBs) due to their superior capacities and rational potassium inserting voltages. However, the sluggish kinetics and poor interface compatibility severely hinder practical application. Herein, Bi0.67 Sb1.33 S3 nanospheres embedded into in situ formed poly(3,4-ethylenedioxythiophene) crosslinked with polythioctic acid (PET@PTA) (Bi0.67 Sb1.33 S3 /PET@PTA) were elaborately conceptualized with hydrogen bonds exchangeable binding (HBEB) sites. Bi0.67 Sb1.33 S3 /PET@PTA exhibits notable self-healing ability and wider temperature adaptability. Bi0.67 Sb1.33 S3 /PET@PTA displays an impressive capacity of 819 mAh g-1 at 0.05 A g-1 , prominent cycle ability with a 73 % capacity conservation after 500 cycles at 2 A g-1 , and high capacity retention of 66 % and 84 % at -40 and 70 °C to that case at room temperature, respectively, for potassium storage. This work provides a new perspective for HBEB sites in maximizing the desirable K+ storage performance.

Superconductivity in Layered van der Waals Hydrogenated Germanene at High Pressure.

The emergence of superconductivity in two-dimensional (2D) materials has attracted tremendous research efforts because the origins and mechanisms behind the unexpected and fascinating superconducting phenomena remain unclear. In particular, the superconductivity can survive in 2D systems even with weakened disorder and broken spatial inversion symmetry. Here, structural and superconducting transitions of 2D van der Waals (vdW) hydrogenated germanene (GeH) are observed under compression and decompression processes. GeH possesses a superconducting transition with a critical temperature (Tc) of 5.41 K at 8.39 GPa. A crystalline to amorphous transition occurs at 16.80 GPa, while superconductivity remains. An abnormal increase of Tc up to 6.11 K was observed during the decompression process, while the GeH remained in the 2D amorphous phase. A combination study of in situ high-pressure synchrotron X-ray diffraction, in situ high-pressure Raman spectroscopy, transition electron microscopy, and density functional theory simulations suggests that the superconductivity in 2D vdW GeH is attributed to the increased density of states at the Fermi level as well as the enhanced electron-phonon coupling effect under high pressure even in the form of an amorphous phase. The unique pressure-induced phase transition of GeH from 2D crystalline to 2D amorphous metal hydride provides a promising platform to study the mechanisms of amorphous hydride superconductivity.

Comparative and phylogenetic analysis based on chloroplast genome of Heteroplexis (Compositae), a protected rare genus.

BACKGROUND: Heteroplexis Chang is an endangered genus endemic to China with important ecological and medicinal value. However, due to the lack of genetic data, our conservation strategies have repeatedly been delayed by controversial phylogenetic (molecular) relationships within the genera. In this study, we reported three new Heteroplexis chloroplast (cp.) genomes (H. vernonioides, H. impressinervia and H. microcephala) to clarify phylogenetic relationships between species allocated in this genus and other related Compositae. RESULTS: All three new cp. genomes were highly conserved, showing the classic four regions. Size ranged from 152,984 - 153,221 bp and contained 130 genes (85 protein-coding genes, 37 tRNA, eight rRNA) and two pseudogenes. By comparative genomic and phylogenetic analyses, we found a large-scale inversion of the entire large single-copy (LSC) region in H. vernonioides, H. impressinervia and H. microcephala, being experimentally verified by PCR. The inverted repeat (IR) regions showed high similarity within the five Heteroplexis plastomes, showing small-size contractions. Phylogenetic analyses did not support the monophyly of Heteroplexis genus, whereas clustered the five species within two differentiated clades within Aster genus. These phylogenetic analyses suggested that the five Heteroplexis species might be subsumed into the Aster genus. CONCLUSION: Our results enrich the data on the cp. genomes of the genus Heteroplexis, providing valuable genetic resources for future studies on the taxonomy, phylogeny, and evolution of Aster genus.

Haloterrigena gelatinilytica sp. nov., a new extremely halophilic archaeon isolated from salt-lake.

Two extremely halophilic strains, designated SYSU A558-1T and SYSU A121-1, were isolated from a saline sediment sample collected from Aiding salt-lake, China. Cells of strains SYSU A558-1T and SYSU A121-1 were Gram-stain-negative, coccoid, and non-motile. The strains were aerobic and grew at NaCl concentration of 10-30% (optimum, 20-22%), at 20-55 °C (optimum, 37-42 °C) and at pH 6.5-8.5 (optimum, 7.0-8.0). Cells lysed in distilled water. The polar lipids were phosphatidyl choline, phosphatidylglycerol phosphate methyl ester, disulfated diglycosyl diether-1 and unidentified glycolipid. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that the two strains SYSU A558-1T and SYSU A121-1 were closely related to the membranes of the genus Haloterrigena. Phylogenetic and phylogenomic trees of strains SYSU A558-1T and SYSU A121-1 demonstrated a robust clade with Haloterrigena turkmenica, Haloterrigena salifodinae and Haloterrigena salina. The genomic DNA G + C content of strains SYSU A558-1T and SYSU A121-1 were 65.8 and 65.0%, respectively. Phenotypic, phylogenetic, chemotaxonomic and genome analysis suggested that the two strains SYSU A558-1T and SYSU A121-1 represent a novel species of the genus Haloterrigena, for which the name Haloterrigena gelatinilytica sp. nov. is proposed. The type strain is SYSU A558-1T (= KCTC 4259T = CGMCC 1.15953T).

High-Pressure Synthesis and Stability Enhancement of Lithium Pentazolate.

The pentazolate anion, cyclo-N5-, has received extensive attention as a new generation of energetic species for explosive or propulsion applications. Binary pentazolate compounds have been obtained under high-pressure conditions and their stability enhancement is crucial for obtaining more competitive high energy density materials (HEDMs). Here, we report the synthesis of a new solid phase of lithium pentazolate (space group P21/c) through the chemical transformation of pure lithium azide under high-pressure and high-temperature conditions. Upon decompression, the structural transition from P21/c-LiN5 to P21/m-LiN5 at ∼15.6 GPa was observed for the first time. Cyclo-N5- can be traced down to ∼5.7 GPa at room temperature and recovered to ambient pressure under a low-temperature condition (80 K). Our results reveal the enhancement of pentazolate anion stability with the increasing content of metal cations and demonstrate that low temperature is an effective route for the recovery of the pentazolate anion.

Pressure-Induced Mixed States Caused by Spin-Elastic Interactions during First-Order Spin Phase Transition in Spin Crossover Compounds.

Recently, the possibility of exploiting the phenomenon of spin transition (ST) has been intensively investigated; therefore, it is particularly important to study the behavior of ST under various stimuli. Here, the shape and content of the intermediate phase of ST in Hoffmann-like compounds [Fe(Fpz)2M(CN)4] (M = Pt, Pd) under external stimuli are studied. For this purpose, magnetic and Raman spectroscopy studies were carried out. In pressure-induced spin transition (PIST), a mixture of high-spin and low-spin states appears, while in temperature-induced spin transition (TIST), a homogeneous state occurs. The first-order ST induced by pressure has a hysteresis but is not abrupt. However, the temperature-induced spin transition at ambient pressure is hysteretic and abrupt. To investigate this difference, we discuss using a thermodynamic model that considers elastic interactions, showing that the slope of the hysteresis loop is related to the appearance of internal pressure, which is related to the difference in sample compressibility under high-spin and low-spin states.

Pressure-Driven Abnormal Emission Blue-Shift of Lead-Free Halide Double Perovskite Cs2AgInCl6 Nanocrystals.

Lead-free halide double perovskites (DPs) have been proposed as stable and promising alternatives to lead halide perovskites. Understanding the structural-optical properties of halide DPs is important for their applications. In this study, Cs2AgInCl6 DP nanocrystals, with a direct band gap, were synthesized and studied. Because of a strong electron-phonon coupling leading to exciton self-trapping, a broad emission with a large Stokes shift of Cs2AgInCl6 DP nanocrystals is observed. We observed an abnormal blue-shifted emission accompanied by a red-shifted direct absorption edge because of the reduced electron-phonon coupling under compression in the cubic phase Cs2AgInCl6 DP nanocrystals. Our study clarified the basic structural-optical correlation of halide DPs and may promote their application in related fields.