Breaking the vitrification limitation of monatomic metals.

The question of whether all materials can solidify into the glassy form proposed by Turnbull half a century ago remains unsolved. Some of the simplest systems of monatomic metals have not been vitrified, especially the close-packed face-centred cubic metals. Here we report the vitrification of gold, which is notoriously difficult to be vitrified, and several similar close-packed face-centred cubic and hexagonal metals using a method of picosecond pulsed laser ablation in a liquid medium. The vitrification occurs through the rapid cooling during laser ablation and the inhibition of nucleation by the liquid medium. Using this method, a large number of atomic configurations, including glassy configurations, can be generated simultaneously, from which a stable glass state can be sampled. Simulations demonstrate that the favourable stability of monatomic metals stems from the strong topological frustration of icosahedra-like clusters. Our work breaks the limitation of the glass-forming ability of matter, indicating that vitrification is an intrinsic property of matter and providing a strategy for the preparation and design of metallic glasses from an atomic configuration perspective.

High-temperature bulk metallic glasses developed by combinatorial methods.

Since their discovery in 19601, metallic glasses based on a wide range of elements have been developed2. However, the theoretical prediction of glass-forming compositions is challenging and the discovery of alloys with specific properties has so far largely been the result of trial and error3-8. Bulk metallic glasses can exhibit strength and elasticity surpassing those of conventional structural alloys9-11, but the mechanical properties of these glasses are critically dependent on the glass transition temperature. At temperatures approaching the glass transition, bulk metallic glasses undergo plastic flow, resulting in a substantial decrease in quasi-static strength. Bulk metallic glasses with glass transition temperatures greater than 1,000 kelvin have been developed, but the supercooled liquid region (between the glass transition and the crystallization temperature) is narrow, resulting in very little thermoplastic formability, which limits their practical applicability. Here we report the design of iridium/nickel/tantalum metallic glasses (and others also containing boron) with a glass transition temperature of up to 1,162 kelvin and a supercooled liquid region of 136 kelvin that is wider than that of most existing metallic glasses12. Our Ir-Ni-Ta-(B) glasses exhibit high strength at high temperatures compared to existing alloys: 3.7 gigapascals at 1,000 kelvin9,13. Their glass-forming ability is characterized by a critical casting thickness of three millimetres, suggesting that small-scale components for applications at high temperatures or in harsh environments can readily be obtained by thermoplastic forming14. To identify alloys of interest, we used a simplified combinatorial approach6-8 harnessing a previously reported correlation between glass-forming ability and electrical resistivity15-17. This method is non-destructive, allowing subsequent testing of a range of physical properties on the same library of samples. The practicality of our design and discovery approach, exemplified by the identification of high-strength, high-temperature bulk metallic glasses, bodes well for enabling the discovery of other glassy alloys with exciting properties.

MEIKIN expression and its C-terminal phosphorylation by PLK1 is closely related the metaphase-anaphase transition by affecting cyclin B1 and Securin stabilization in meiotic oocyte.

Oocyte meiotic maturation failure and chromosome abnormality is one of the main causes of infertility, abortion, and diseases. The mono-orientation of sister chromatids during the first meiosis is important for ensuring accurate chromosome segregation in oocytes. MEIKIN is a germ cell-specific protein that can regulate the mono-orientation of sister chromatids and the protection of the centromeric cohesin complex during meiosis I. Here we found that MEIKIN is a maternal protein that was highly expressed in mouse oocytes before the metaphase I (MI) stage, but became degraded by the MII stage and dramatically reduced after fertilization. Strikingly, MEIKIN underwent phosphorylation modification after germinal vesicle breakdown (GVBD), indicating its possible function in subsequent cellular event regulation. We further showed that MEIKIN phosphorylation was mediated by PLK1 at its carboxyl terminal region and its C-terminus was its key functional domain. To clarify the biological significance of meikin degradation during later stages of oocyte maturation, exogenous expression of MEIKIN was employed, which showed that suppression of MEIKIN degradation resulted in chromosome misalignment, cyclin B1 and Securin degradation failure, and MI arrest through a spindle assembly checkpoint (SAC)-independent mechanism. Exogenous expression of MEIKIN also inhibited metaphase II (MII) exit and early embryo development. These results indicate that proper MEIKIN expression level and its C-terminal phosphorylation by PLK1 are critical for regulating the metaphase-anaphase transition in meiotic oocyte. The findings of this study are important for understanding the regulation of chromosome segregation and the prevention meiotic abnormality.

Electronic structures and quantum capacitance of twisted bilayer graphene with defects based on three-band tight-binding model.

Twisted bilayer graphene (tBLG) with C vacancies would greatly improve the density of states (DOS) around the Fermi level (EF) and quantum capacitance; however, the single-band tight-binding model only considering pz orbitals cannot accurately capture the low-energy physics of tBLG with C vacancies. In this work, a three-band tight-binding model containing three p orbitals of C atoms is proposed to explore the modulation mechanism of C vacancies on the DOS and quantum capacitance of tBLG. We first obtain the hopping integral parameters of the three-band tight-binding model, and then explore the electronic structures and the quantum capacitance of tBLG at a twisting angle of θ = 1.47° under different C vacancy concentrations. The impurity states contributed by C atoms with dangling bonds located around the EF and the interlayer hopping interaction could induce band splitting of the impurity states. Therefore, compared with the quantum capacitance of pristine tBLG (∼18.82 µF cm-2) at zero bias, the quantum capacitance is improved to ∼172.76 µF cm-2 at zero bias, and the working window with relatively large quantum capacitance in the low-voltage range is broadened in tBLG with C vacancies due to the enhanced DOS around the EF. Moreover, the quantum capacitance of tBLG is further increased at zero bias with an increase of the C vacancy concentration induced by more impurity states. These findings not only provide a suitable multi-band tight-binding model to describe tBLG with C vacancies but also offer theoretical insight for designing electrode candidates for low-power consumption devices with improved quantum capacitance.

Observation of an isothermal glass transition in metallic glasses.

Glass transition, commonly manifested upon cooling a liquid, is continuous and cooling rate dependent. For decades, the thermodynamic basis in liquid-glass transition has been at the center of debate. Here, long-time isothermal annealing was conducted via molecular dynamics simulations for metallic glasses to explore the connection of physical aging in supercooled liquid and glassy states. An anomalous two-step aging is observed in various metallic glasses, exhibiting features of supercooled liquid dynamics in the first step and glassy dynamics in the second step, respectively. Furthermore, the transition potential energy is independent of initial states, proving that it is intrinsic for a metallic glass at a given temperature. We propose that the observed dynamic transition from supercooled liquid dynamics to glassy dynamics could be glass transition manifested isothermally. On this basis, glass transition is no longer cooling rate dependent, but is shown as a clear phase boundary in the temperature-energy phase diagram. Hence, a modified out-of-equilibrium phase diagram is proposed, providing new insights into the nature of glass transition.

A new isocoumarin derivative from endophytic fungus Pezicula neosporulosa VDB39 from Vaccinium dunalianum.

Four isocoumarin derivatives (1-4) and five phenols (5-9) were obtained from the endophytic fungus Pezicula neosporulosa VDB39, which was isolated from the branches of Vaccinium dunalianum Wight (Ericaceae). Compound 1 is a new derivative of isocoumarin. The structures were elucidated by spectroscopic methods. Single X-ray crystallography confirmed the absolute configuration of compound 1. Additionally, the antiphytopathogenic fungi activity of isocoumarin derivatives (1-4) was evaluated.

Data-driven discovery of a universal indicator for metallic glass forming ability.

Despite the importance of glass forming ability as a major alloy characteristic, it is poorly understood and its quantification has been experimentally laborious and computationally challenging. Here, we uncover that the glass forming ability of an alloy is represented in its amorphous structure far away from equilibrium, which can be exposed by conventional X-ray diffraction. Specifically, we fabricated roughly 5,700 alloys from 12 alloy systems and characterized the full-width at half-maximum, Δq, of the first diffraction peak in the X-ray diffraction pattern. A strong correlation between high glass forming ability and a large Δq was found. This correlation indicates that a large dispersion of structural units comprising the amorphous structure is the universal indicator for high metallic glass formation. When paired with combinatorial synthesis, the correlation enhances throughput by up to 100 times compared to today's state-of-the-art combinatorial methods and will facilitate the discovery of bulk metallic glasses.

Phase Modulation of Self-Gating in Ionic Liquid-Functionalized InSe Field-Effect Transistors.

Understanding the Coulomb interactions between two-dimensional (2D) materials and adjacent ions/impurities is essential to realizing 2D material-based hybrid devices. Electrostatic gating via ionic liquids (ILs) has been employed to study the properties of 2D materials. However, the intrinsic interactions between 2D materials and ILs are rarely addressed. This work studies the intersystem Coulomb interactions in IL-functionalized InSe field-effect transistors by displacement current measurements. We uncover a strong self-gating effect that yields a 50-fold enhancement in interfacial capacitance, reaching 550 nF/cm2 in the maximum. Moreover, we reveal the IL-phase-dependent transport characteristics, including the channel current, carrier mobility, and density, substantiating the self-gating at the InSe/IL interface. The dominance of self-gating in the rubber phase is attributed to the correlation between the intra- and intersystem Coulomb interactions, further confirmed by Raman spectroscopy. This study provides insights into the capacitive coupling at the InSe/IL interface, paving the way to developing liquid/2D material hybrid devices.

miR-466 Contributes to the Enhanced Antitumor Effect of Bortezomib on Non-Small-Cell Lung Cancer by Inhibiting CCND1.

INTRODUCTION: Changes in microRNAs (miRs) contribute to the alternative chemo-resistance of cancers. Bortezomib (BTZ) is a well-characterized anticancer agent that inhibits proteasome, and its effect is associated with the function of miRs. Based on the data of microarray assay and comprehensive bioinformatics analyses, in the current study, we explored the role of miR-466 and its downstream effector CCND1 in the BTZ-resistance of non-small-cell lung cancer (NSCLC) cells. METHODS: miR expression profiles in NSCLC tissues and paratumor tissues were determined with microarray assay. The potential miR involved in the chemo-resistance of NSCLC cells was explored via a series of bioinformatics analyses, and miR-466 was selected. Afterward, levels of miR-466 and CCND1 were investigated in NSCLC samples and analyzed by clinicopathologic parameters, including age, sex, stage of NSCLC, tumor size, tumor differentiation status, and lymphocytic infiltration status. The expression of CCND1 and miR-466 was then modulated in vitro to explore the influence on cell phenotypes, which was then verified with mouse models. RESULTS: Based on microarray detection, 287 miRs were dysexpressed between NSCLC tissues and paratumor tissues, including 90 upregulated members and 197 downregulated members. After bioinformatics analyses and reverse transcription quantitative PCR validation, miR-466 and CCND1 were selected. Following clinical investigations, miR-466 was downregulated, while CCND1 was upregulated in NSCLC samples, contributing to the advanced cancer progression. The overexpression of CCND1 increased cell viability, suppressed cell apoptosis, decreased p21 and induced N-cadherin, CCND2, and CDK4 under BTZ treatment. The induced expression of miR-466 re-sensitized NSCLC cells to BTZ treatment. In the animal model, the overexpression of CCND1 impaired the inhibitory effect of BTZ on the growth and metastasis of solid tumor, which was restored by miR-466 induction. CONCLUSION: The findings showed that the interaction between BTZ, miR-466, and CCND1 determined the antitumor effect of BTZ on NSCLC.

[Comparative proteomic profiling of hippocampi in mice treated with Jingui Shenqi Pills and Liuwei Dihuang Pills].

The effects of Jingui Shenqi Pills(Jingui) and Liuwei Dihuang Pills(Liuwei) which respectively tonify kidney Yang and kidney Yin on brain function have attracted great attention, while the differences of protein expression regulated by Jingui and Liuwei remain to be studied. This study explored the difference of protein expression profiles in the hippocampi of mice orally administrated with the two drugs for 7 days. The protein expression was quantified using LC-MS/MS. The results showed that among the 5 860 proteins tested, 151, 282 and 75 proteins responded to Jingui alone, Liuwei alone, and both drugs, respectively. The ratio of up-regulated proteins to down-regulated proteins was 1.627 in Jingui group while only 0.56 in Liuwei group. The proteins up-regulated by Jingui were mainly involved in membrane transport, synaptic vesicle cycle, serotonergic synapse, dopaminergic synapse and so on, suggesting that Jingui may play a role in promoting the transport of neurotransmitter in the nervous system. The proteins down-regulated by Liuwei were mainly involved in membrane transport, synapse, ion transport(potassium and sodium transport), neurotransmitter transport, innate and acquired immune responses, complement activation, inflammatory response, etc. In particular, Liuwei showed obvious down-regulation effect on the members of solute carrier(SLC) superfamily, which suggested that Liuwei had potential inhibitory effect on membrane excitation and transport. Finally, consistent results were obtained in the normal mouse and the mouse model with corticosterone-induced depressive-like behavior. This study provides an experimental basis for understanding the effect of Jingui and Liuwei on brain function from protein network.

The contributions of mesoderm-derived cells in liver development.

The liver is an indispensable organ for metabolism and drug detoxification. The liver consists of endoderm-derived hepatobiliary lineages and various mesoderm-derived cells, and interacts with the surrounding tissues and organs through the ventral mesentery. Liver development, from hepatic specification to liver maturation, requires close interactions with mesoderm-derived cells, such as mesothelial cells, hepatic stellate cells, mesenchymal cells, liver sinusoidal endothelial cells and hematopoietic cells. These cells affect liver development through precise signaling events and even direct physical contact. Through the use of new techniques, emerging studies have recently led to a deeper understanding of liver development and its related mechanisms, especially the roles of mesodermal cells in liver development. Based on these developments, the current protocols for in vitro hepatocyte-like cell induction and liver-like tissue construction have been optimized and are of great importance for the treatment of liver diseases. Here, we review the roles of mesoderm-derived cells in the processes of liver development, hepatocyte-like cell induction and liver-like tissue construction.

Dehydration of Electrochemically Protonated Oxide: SrCoO2 with Square Spin Tubes.

Controlling oxygen deficiencies is essential for the development of novel chemical and physical properties such as high-Tc superconductivity and low-dimensional magnetic phenomena. Among reduction methods, topochemical reactions using metal hydrides (e.g., CaH2) are known as the most powerful method to obtain highly reduced oxides including Nd0.8Sr0.2NiO2 superconductor, though there are some limitations such as competition with oxyhydrides. Here we demonstrate that electrochemical protonation combined with thermal dehydration can yield highly reduced oxides: SrCoO2.5 thin films are converted to SrCoO2 by dehydration of HSrCoO2.5 at 350 °C. SrCoO2 forms square (or four-legged) spin tubes composed of tetrahedra, in contrast to the conventional infinite-layer structure. Detailed analyses suggest the importance of the destabilization of the SrCoO2.5 precursor by electrochemical protonation that can greatly alter reaction energy landscape and its gradual dehydration (H1-xSrCoO2.5-x/2) for the SrCoO2 formation. Given the applicability of electrochemical protonation to a variety of transition metal oxides, this simple process widens possibilities to explore novel functional oxides.

Changes in Bacterial and Fungal Microbiomes Associated with Tomatoes of Healthy and Infected by Fusarium oxysporum f. sp. lycopersici.

Fusarium wilt of tomato caused by the pathogen Fusarium oxysporum f. sp. lycopersici (Fol) is one of the most devastating soilborne diseases of tomato. To evaluate whether microbial community composition associated with Fol-infected tomato is different from healthy tomato, we analyzed the tomato-associated microbes in both healthy and Fol-infected tomato plants at both the taxonomic and functional levels; both bacterial and fungal communities have been characterized from bulk soil, rhizosphere, rhizoplane, and endosphere of tomatoes using metabarcoding and metagenomics approaches. The microbial community (bacteria and fungi) composition of healthy tomato was significantly different from that of diseased tomato, despite similar soil physicochemical characteristics. Both fungal and bacterial diversities were significantly higher in the tomato plants that remained healthy than in those that became diseased; microbial diversities were also negatively correlated with the concentration of Fol pathogen. Network analysis revealed the microbial community of healthy tomato formed a larger and more complex network than that of diseased tomato, probably providing a more stable community beneficial to plant health. Our findings also suggested that healthy tomato contained significantly greater microbial consortia, including some well-known biocontrol agents (BCAs), and enriched more functional genes than diseased tomato. The microbial taxa enriched in healthy tomato plants are recognized as potential suppressors of Fol pathogen invasion.

Magnetotransport in hybrid InSe/monolayer graphene on SiC.

The magnetotransport properties of a hybrid InSe/monolayer graphene in a SiC system are systematically studied. Compared to those of its bare graphene counterpart, in InSe/graphene, we can effectively modify the carrier density, mobility, effective mass, and electron-electron (e-e) interactions enhanced by weak disorder. We show that in bare graphene and hybrid InSe/graphene systems, the logarithmic temperature (lnT) dependence of the Hall slope R H = Î´R xy /δB = Î´ρ xy /δB can be used to probe e-e interaction effects at various temperatures even when the measured resistivity does not show a lnT dependence due to strong electron-phonon scattering. Nevertheless, one needs to be certain that the change of R H is not caused by an increase of the carrier density by checking the magnetic field position of the longitudinal resistivity minimum at different temperatures. Given the current challenges in gating graphene on SiC with a suitable dielectric layer, our results suggest that capping a van der Waals material on graphene is an effective way to modify the electronic properties of monolayer graphene on SiC.

Post-translational modification of KRAS: potential targets for cancer therapy.

Aberrant activation of the RAS superfamily is one of the critical factors in carcinogenesis. Among them, KRAS is the most frequently mutated one which has inspired extensive studies for developing approaches to intervention. Although the cognition toward KRAS remains far from complete, mounting evidence suggests that a variety of post-translational modifications regulate its activation and localization. In this review, we summarize the regulatory mode of post-translational modifications on KRAS including prenylation, post-prenylation, palmitoylation, ubiquitination, phosphorylation, SUMOylation, acetylation, nitrosylation, etc. We also highlight the recent studies targeting these modifications having exhibited potent anti-tumor activities.

Configuration correlation governs slow dynamics of supercooled metallic liquids.

The origin of dramatic slowing down of dynamics in metallic glass-forming liquids toward their glass transition temperatures is a fundamental but unresolved issue. Through extensive molecular dynamics simulations, here we show that, contrary to the previous beliefs, it is not local geometrical orderings extracted from instantaneous configurations but the intrinsic correlation between configurations that captures the structural origin governing slow dynamics. More significantly, it is demonstrated by scaling analyses that it is the correlation length extracted from configuration correlation rather than dynamic correlation lengths that is the key to determine the drastic slowdown of supercooled metallic liquids. The key role of the configuration correlation established here sheds important light on the structural origin of the mysterious glass transition and provides an essential piece of the puzzle for the development of a universal theoretical understanding of glass transition in glasses.

Telomerase Reverse Transcriptase and p53 Regulate Mammalian Peripheral Nervous System and CNS Axon Regeneration Downstream of c-Myc.

Although several genes have been identified to promote axon regeneration in the CNS, our understanding of the molecular mechanisms by which mammalian axon regeneration is regulated is still limited and fragmented. Here by using female mouse sensory axon and optic nerve regeneration as model systems, we reveal an unexpected role of telomerase reverse transcriptase (TERT) in regulation of axon regeneration. We also provide evidence that TERT and p53 act downstream of c-Myc to control sensory axon regeneration. More importantly, overexpression of p53 in sensory neurons and retinal ganglion cells is sufficient to promote sensory axon and optic never regeneration, respectively. The study reveals a novel c-Myc-TERT-p53 signaling pathway, expanding horizons for novel approaches promoting CNS axon regeneration.SIGNIFICANCE STATEMENT Despite significant progress during the past decade, our understanding of the molecular mechanisms by which mammalian CNS axon regeneration is regulated is still fragmented. By using sensory axon and optic nerve regeneration as model systems, the study revealed an unexpected role of telomerase reverse transcriptase (TERT) in regulation of axon regeneration. The results also delineated a c-Myc-TERT-p53 pathway in controlling axon growth. Last, our results demonstrated that p53 alone was sufficient to promote sensory axon and optic nerve regeneration in vivo Collectively, the study not only revealed a new mechanisms underlying mammalian axon regeneration, but also expanded the pool of potential targets that can be manipulated to enhance CNS axon regeneration.

Tritium diffusion in a Li2TiO3 crystal terminated with the (001) surface from first-principles calculations.

The tritium release behavior of the Li2TiO3 crystal has become an important index to evaluate its comprehensive performance as a solid breeder material in nuclear fusion reactors. The tritium diffusion on the surface (surface diffusion) and diffusion from the inside to the surface (hopping diffusion) in Li2TiO3 crystals with a 1/3-Li(001) surface are systematically investigated by the first-principles method. Possible adsorption sites, diffusion pathways and energy barriers of surface diffusion and hopping diffusion have been calculated and analyzed, respectively. Tritium atoms are found to diffuse preferentially along the [100] direction on the surface and two equivalent pathways across the surface were identified. The obtained activation energies are about 0.50 eV for surface diffusion and 1.56 eV for hopping diffusion. The local density of states and Bader charge for typical surface diffusion and hopping diffusion pathways are calculated and analyzed. The results reveal that the tritium (T) atom bonds with neighboring oxygen (O) atoms during the surface diffusion, while the T-O interaction is significantly weakened in the hopping diffusion which results in the higher activation energy than that of surface diffusion. In combination with our previous work, a complete tritium diffusion model for the Li2TiO3 crystal is proposed and the corresponding tritium diffusion coefficients are obtained. Our obtained activation energies are in the same range as previous experimental data and could provide theoretical support for the future related experiments.

Molecularly Thin Electrolyte for All Solid-State Nonvolatile Two-Dimensional Crystal Memory.

A molecularly thin electrolyte is developed to demonstrate a nonvolatile, solid-state, one-transistor (1T) memory based on an electric-double-layer (EDL) gated WSe2 field-effect transistor (FET). The custom-designed monolayer electrolyte consists of cobalt crown ether phthalocyanine and lithium ions, which are positioned by field-effect at either the surface of the WSe2 channel or an h-BN capping layer to achieve "1" or "0", respectively. Bistability in the monolayer electrolyte memory is significantly improved by the h-BN cap with density functional theory (DFT) calculations showing enhanced trapping of Li+ near h-BN due to a ∼1.34 eV increase in the absolute value of the adsorption energy compared to vacuum. The threshold voltage shift between the two states corresponds to a change in charge density of ∼2.5 × 1012 cm-2, and an On/Off ratio exceeding 104 at a back gate voltage of 0 V. The On/Off ratio remains stable after 1000 cycles and the retention time for each state exceeds 6 h (max measured). When the write time approaches 1 ms, the On/Off ratio remains >102, showing that the monolayer electrolyte-gated FET can respond on time scales similar to existing flash memory. The data suggest that faster switching times and lower switching voltages could be feasible by top gating.

Calcium/calmodulin-dependent protein kinase II regulates mammalian axon growth by affecting F-actin length in growth cone.

While axon regeneration is a key determinant of functional recovery of the nervous system after injury, it is often poor in the mature nervous system. Influx of extracellular calcium (Ca2+ ) is one of the first phenomena that occur following axonal injury, and calcium/calmodulin-dependent protein kinase II (CaMKII), a target substrate for calcium ions, regulates the status of cytoskeletal proteins such as F-actin. Herein, we found that peripheral axotomy activates CaMKII in dorsal root ganglion (DRG) sensory neurons, and inhibition of CaMKII impairs axon outgrowth in both the peripheral and central nervous systems (PNS and CNS, respectively). Most importantly, we also found that the activation of CaMKII promotes PNS and CNS axon growth, and regulatory effects of CaMKII on axon growth occur via affecting the length of the F-actin. Thus, we believe our findings provide clear evidence that CaMKII is a critical modulator of mammalian axon regeneration.