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Sliding ferroelectricity (SFE) found in two-dimensional (2D) van der Waals (vdW) materials, such as BN and transition-metal dichalcogenides bilayers, open an avenue for 2D ferroelectric materials. The multiferroic coupling in 2D SFE materials is expected to bring about new concepts for spintronic memory devices. Here, using first-principles calculations, we demonstrate that the recently-synthesized MnSe multilayers [ACS Nano 15, 13794 (2021)] have large reversible out-of-plane electric polarization (~10.6 pC/m) and moderate interlayer sliding barriers superior to the existing 2D SFE materials. More interestingly, the intrinsic electric polarization is also accompanied by nonzero net magnetic moments whose direction is dependent on the electric polarization direction and thus can be switched by interlayer sliding. Additionally, both the SFE and magnetoelectric coupling can be effectively regulated by external strain and/or hole doping. Our findings suggest the potential of MnSe multilayers in 2D multiferroic and spintronic applications.

Potassium-ion batteries (PIBs) are promising candidates for next-generation energy storage devices due to the earth abundance of potassium, low cost, and stable redox potentials. However, the lack of promising high-performance electrode materials for the intercalation/deintercalation of large potassium ions is a major challenge up to date. Herein, we report a novel uniform nickel selenide nanoparticles encapsulated in nitrogen-doped carbon (defined as “NiSe@NC”) as an anode for PIBs, which exhibits superior rate performance and cyclic stability. Benefiting from the unique hierarchical core—shell like nanostructure, the intrinsic properties of metal—selenium bonds, synergetic effect of different components, and a remarkable pseudocapacitance effect, the anode exhibits a very high reversible capacity of 438 mA·h·g−1 at 50 mA·g−1, an excellent rate capability, and remarkable cycling performance over 2,000 cycles. The electrochemical mechanism were investigated by the in-situ X-ray diffraction, ex-situ high-resolution transmission electron microscopy, selected area electron diffraction, and first principle calculations. In addition, NiSe@NC anode also shows high reversible capacity of 512 mA·h·g−1 at 100 mA·g−1 with 84% initial Coulombic efficiency, remarkable rate performance, and excellent cycling life for sodium ion batteries. We believe the proposed simple approach will pave a new way to synthesize suitable anode materials for secondary ion batteries.

The three-phase structure of the solid fermentation substrates is composed by the solid, liquid and gas phases, adjusting the ratio of the three-phase structure has proven to be a strategy that can better serve the growth of microorganisms. In this study, the effect of the three-phase structure of the cultivated substrate on the growth of Lentinula edodes was evaluated. Our results showed that the liquid phase was most impacted by the particle size and moisture content among the three-phase. Further analysis of the three-phase structure index (TPSI) showed that the highest efficiency of L. edodes growth was achieved at TPSI value of 23.3, and the liquid phase was the most affected variable on the TPSI of cultivated substrates among the three phases. Further, to determine the optimal water environment for L. edodes in the substrates, three types of water containing four proton components in the cultivation substrate were identified based on distributed exponential curve fitting of transverse relaxation (T2), namely, bound water T2b, free water T21a and T21b, and bulk water T22. L. edodes exhibited the best growth efficiency on elm (59% moisture content), peanut shell (52% moisture content) and apricot (56% moisture content) substrates, all of which were filled with free water and without bulk water, respectively. The same conclusion was also obtained in the mixed material cultivation substrate. In overview, L. edodes had the best growth efficiency in substrates filled with free water and not containing bulk water, which enabled proton analysis based on LF-NMR spectroscopy to provide new insights into the moisture content of wood-rot fungal cultivated substrates.

Plasmons in strongly correlated systems are attracting considerable attention due to their unconventional behavior caused by electronic correlation effects. Recently, flat plasmons with nearly dispersionless frequency-wave vector relations have drawn significant interest because of their intriguing physical origin and promising applications. However, these flat plasmons exist primarily in low-dimensional materials with limited wave vector magnitudes (q −1). Here, we show that long-lived flat plasmons can propagate up to ~1.2 Å−1 in α-Ti2O3, a strongly correlated three-dimensional Mott-insulator, with an ultra-small energy fluctuation (2O3. Moreover, these flat plasmons are not affected by Landau damping over a wide range of wave vectors (q −1) due to symmetry constrains on the electron wavefunctions. Our work provides a strategy for exploring flat plasmons in strongly correlated systems, which in turn may give rise to novel plasmonic devices in which flat and long-lived plasmons are desirable.

Identifying new and economical means to utilize diverse lignocellulosic biomass is an urgent task. Ganoderma lucidum is a well-known edible and medicinal basidiomycete with an excellent ability to degrade a wide range of cellulosic biomass, and its nutrient use efficiency is closely related to the activity of extracellular cellulase. Intracellular nicotinamide adenine dinucleotide (NAD+) biosynthesis is controlled in response to nutritional status, and NAD+ is an essential metabolite involved in diverse cellular processes. Nicotinamide mononucleotide adenylyltransferase (NMNAT) is a common enzyme in three NAD+ synthesis pathways. In this study, a homologous gene of nmnat was cloned from G. lucidum and two G. lucidum overexpression strains, OE::nmnat4 and OE::nmnat19, were constructed using an Agrobacterium tumefaciens-mediated transformation method. The G. lucidum nmnat overexpression strains showed obviously increased colony growth on different carbon sources, and intracellular Ca2+ concentrations in the G. lucidum OE::nmnat4 and OE::nmnat19 strains were increased by 2.04- and 2.30-fold, respectively, compared with those in the wild-type (WT) strains. In the G. lucidum OE::nmnat4 and OE::nmnat19 strains, endo-β-glucanase (CMCase) activity increased by approximately 2.8- and 3-fold, while β-glucosidase (pNPGase) activity increased by approximately 1.9- and 2.1-fold, respectively, compared with the activity in the WT strains. Furthermore, overexpression of NAD+ synthesis pathways was found to elicit cellulase production by increasing the intracellular Ca2+ concentration. In summary, this study is the first to demonstrate that increased intracellular NAD+ contents through overexpression of the nmnat gene of NAD+ synthesis pathways may increase cellulase production by increasing intracellular Ca2+ concentrations in G. lucidum. KEY POINTS: • The concentration of NAD+influences cellulase production in G. lucidum. • The concentration of NAD+influences the intracellular Ca2+concentration in G. lucidum. • The concentration of NAD+influences cellulase production by eliciting a change in intracellular Ca2+in G. lucidum.

Weak ion diffusion and electron transport due to limited interlayer spacing and poor electrical conductivity have been identified as critical roadbacks for fast and abundant energy storage of both MoS2-based lithium ion batteries (LIBs) and sodium ion batteries (SIBs). In this work, MoS2 porous-hollow nanorods (MoS2/m-C800) have been designed and synthesized via an annealing-followed chemistry-intercalated strategy to solve the two issues. They are uniformly assembled from ultrathin MoS2 nanosheets, deviated to the rod-axis direction, with expanded interlayer spacing due to alternate intercalation of N-doped carbon monolayers between the adjacent MoS2 monolayers. Electrochemical studies of the MoS2/m-C800 sample, as an anode of LIBs, demonstrate that the superstructure can deliver a reversible discharge capacity of 1,170 mAh•g−1 after 100 cycles at 0.2 A•g−1 and maintain a reversible capacity of 951 mAh•g−1 at 1.25 A•g−1 after 350 cycles. While for SIBs, the superstructure also delivers a reversible discharge capacity of 350 mAh•g−1 at 0.5 A•g−1 after 500 cycles and exhibits superior rate capacity of 238 mAh•g−1 at 15 A•g−1.The excellent electrochemical performance is closely related with the hierarchical superstructures, including expanded interlayer spacing, alternate intercalation of carbon monolayers and mesoporous feature, which effectively reduce ion diffusion barrier, shorten ion diffusion paths and improve electrical conductivity.

Topological insulators (TIs) are considered as ideal platforms for generating large spin Hall conductivity (SHC), however, the bulk carrier problem, which is unavoidable in TIs, hinders their practical applications. Recently, topological semimetals (TSMs) have been proposed to achieve large SHC to replace TIs. However, the ideal TSM candidates with large SHC are still lacking. In terms of first-principles calculations, we predict that Ta3As family compounds exhibit complex crossing nodal-lines (CNL) properties in absence of the spin-orbit coupling (SOC). However, they transfer to Dirac TSMs under the influence of strong SOC, and present large SHC around Fermi level in particular. Remarkably, the SHC value of Ta3Y (Y = As, Sb, Bi) is around 1500–1700 $$(\hbar /e)({\mathrm{{\Omega}}} \cdot {\mathrm{cm}})^{ - 1}$$ ( ħ / e ) ( Ω ⋅ cm ) − 1 , which is comparable to noble metal Pt and much larger than TIs, Weyl TSMs, and 4d/5d transition metals. Our work not only suggests a kind of TSM family with interesting Dirac CNL around Fermi level, but also paves the way for searching large intrinsic SHC materials in complex CNL TSM systems.

Ganoderma lucidum, which contains many pharmacologically active compounds, is regarded as a traditional medicinal fungus. Nevertheless, the scarcity of basic research limits the commercial value and utilization of G. lucidum. As a class of highly conserved, phosphopeptide-binding proteins present in all eukaryotes, 14-3-3 proteins play vital roles in controlling multiple physiological processes, including signal transduction, primary metabolism, and stress responses. However, knowledge of the roles of 14-3-3 proteins in Basidiomycetes is sparse. In this article, two homologs of 14-3-3 proteins, encoded by the two distinct genes GlBmh1 and GlBmh2, were distinguished in G. lucidum. We found that GlBmh1 and GlBmh2 were expressed at various developmental stages, including in vegetative mycelium cultivated on solid medium and in primordia and fruiting bodies. Moreover, we constructed GlBmh1 single-silenced strains, GlBmh2 single-silenced strains, and 14-3-3 double-silenced mutants for further study. When GlBmh1 and GlBmh2 were inhibited by RNA interference, the growth rate of mycelia was decreased, and the distance between the aerial hyphal branches was reduced; responses to various abiotic stresses such as oxidants and cell wall and osmotic stressors were also changed. Furthermore, the contents of secondary metabolite ganoderic acids (GAs) were increased after GlBmh1 and GlBmh2 were simultaneously silenced. Taken together, we provide evidence that implicates potential roles for the two 14-3-3 proteins in affecting growth and GA biosynthesis, thereby providing new insights into the basic functions of 14-3-3 proteins in G. lucidum.

Cullin 4B (CUL4B) is a scaffold protein overexpressed in several solid malignancies. It is known to silence tumor suppressor through post-transcriptional manner. However, its clinical significance and underlying molecular mechanisms in gastric cancer (GC) remain largely unknown. In this study, we found that CUL4B was significantly overexpressed in GC tissues and its overexpression was correlated with lymph node metastasis and poor prognosis. Through gain- and loss-of-function experiments, we showed that CUL4B promotes GC cell invasion and epithelial-mesenchymal transition (EMT) in vitro, as well as tumor growth and metastasis in vivo. Mechanistically, we identified HER2 as a downstream target gene of CUL4B in GC. CUL4B unregulated HER2 expression via transcriptionally repressing miR-125a. Intriguingly, HER2 inhibitors significantly reversed CUL4B-induced EMT in vitro and partially blocked GC metastasis in tumor xenografts with CUL4B overexpression. Finally, we suggested the involvement of the PI3K/AKT pathway in CUL4B-induced HER2 upregulation in GC. In all, we proposed a model for a CUL4B-miR-125a-HER2 oncoprotein axis, which provided novel insight into how HER2 was activated and contributed to GC progression and metastasis.

This study aimed to identify suitable reference genes under three chemical inducers, methyl jasmonate (MeJA), salicylic acid (SA) and hydrogen peroxide (H2O2) in Ganoderma lucidum. In this study, expression stabilities of 14 candidate reference genes had been validated. Four algorithms were used: geNorm, NormFinder, BestKeeper, and RefFinder. Our results showed that, in short time, UCE2 (ubiquitin conjugating enzyme) was the most stable gene both in MeJA and H2O2 treatments, ACTIN (beta-actin) was the most suitable reference gene for SA treatment. ACTIN/UCE2 were considered the most suitable genes to normalize in MeJA, SA and H2O2 conditions. In long time, PP2A (protein phosphatase 2A regulatory subunit) was the most stable gene in MeJA and SA treatments, UCE2 was the most suitable reference gene for H2O2 treatment. PP2A/UBQ1 (polyubiquitin 1) were considered the most suitable genes to normalize in MeJA, SA and H2O2 conditions. Furthermore, target gene, oxidosqualene cyclase (osc), was selected to validate the most and least stable reference genes under different treatments. Our work provided a better support to study the regulatory mechanism of MeJA, SA and H2O2 on biological functions.

A quantum-spin-Hall (QSH) state was achieved experimentally, albeit at a low critical temperature because of the narrow band gap of the bulk material. Twodimensional topological insulators are critically important for realizing novel topological applications. Using density functional theory (DFT), we demonstrated that hydrogenated GaBi bilayers (HGaBi) form a stable topological insulator with a large nontrivial band gap of 0.320 eV, based on the state-of-the-art hybrid functional method, which is implementable for achieving QSH states at room temperature. The nontrivial topological property of the HGaBi lattice can also be confirmed from the appearance of gapless edge states in the nanoribbon structure. Our results provide a versatile platform for hosting nontrivial topological states usable for important nanoelectronic device applications.

Acetic acid at 5–8 mM increased ganoderic acid (GA) accumulation in Ganoderma lucidum. After optimization by the response surface methodology, the GA content reached 5.5/100 mg dry weight, an increase of 105 % compared with the control. The intermediate metabolites of GA biosynthesis, lanosterol and squalene also increased to 47 and 15.8 μg/g dry weight, respectively, in response to acetic acid. Acetic acid significantly induced transcription levels of sqs, lano, hmgs and cyp51 in the GA biosynthesis pathway. An acetic acid-unregulated acetyl coenzyme A synthase (acs) gene was selected from ten candidate homologous acs genes. The results indicate that acetic acid alters the expression of genes related to acetic acid assimilation and increases GA biosynthesis and the metabolic levels of lanosterol, squalene and GA-a, thereby resulting in GA accumulation.

Two-dimensional (2D) transition-metal dichalcogenides (TMDs) exhibit intriguing properties for both fundamental research and potential application in fields ranging from electronic devices to catalysis. Based on first-principles calculations, we proposed a stable form of palladium diselenide (PdSe2) monolayer that can be synthesized by selenizing Pd(111) surface. It has a moderate band gap of about 1.10 eV, a small in-plane stiffness, and electron mobility larger than that of monolayer black phosphorus by more than one order. Additionally, tensile strain can modulate the band gap of PdSe2 monolayer and consequently enhance the infrared light adsorption ability. These interesting properties are quite promising for application in electronic and optoelectronic devices.

A hydroxymethylglutaryl-CoA synthase gene, designated as GlHMGS (GenBank accession No. JN391469) involved in ganoderic acid (GA) biosynthesis pathway was cloned from Ganoderma lucidum. The full-length cDNA of GlHMGS (GenBank accession No. JN391468) was found to contain an open reading frame of 1,413 bp encoding a polypeptide of 471 amino acid residues. The deduced amino acid sequence of GlHMGS shared high homology with other known hydroxymethylglutaryl-CoA synthase (HMGS) enzymes. In addition, functional complementation of GlHMGS in a mutant yeast strain YSC1021 lacking HMGS activity demonstrated that the cloned cDNA encodes a functional HMGS. A 1,561 bp promoter sequence was isolated and its putative regulatory elements and potential specific transcription factor binding sites were analyzed. GlHMGS expression profile analysis revealed that salicylic acid, abscisic acid and methyl jasmonate up-regulated GlHMGS transcript levels over the control. Further expression analysis revealed that the developmental stage and carbon source had significant effects on GlHMGS transcript levels. GlHMGS expression peaked on day 16 before decreasing with prolonged culture time. The highest mRNA level was observed when the carbon source was maltose. Overexpression of GlHMGS enhanced GA content in G. lucidum. This study provides useful information for further studying this gene and on its function in the ganoderic acid biosynthetic pathway in G. lucidum.

This study investigated the role of the mevalonate pyrophosphate decarboxylase gene in the triterpene biosynthetic pathway of Ganoderma lucidum. The mevalonate pyrophosphate decarboxylase gene (mvd) was isolated using a degenerate primer-PCR technique. An analysis of the Gl-mvd transcription profile revealed a positive correlation between the expression of the Gl-mvd gene and triterpene content changes in G. lucidum during development. Furthermore, a promoter deletion analysis was conducted in G. lucidum to investigate the promoter activity and the role of methyl jasmonate (MeJA) responsive elements in the mvd promoter under the MeJA elicitor. The overexpression of Gl-mvd increased triterpene accumulation compared with the wild-type strain and increased the expression of several genes involved in the triterpene biosynthetic pathway. The findings of this study suggest that mvd may play an important role in triterpene biosynthesis regulation. Moreover, there may be the interactions among the genes involved in the triterpene biosynthetic pathway in the G. lucidum. Additionally, this study provides an approach for improving triterpene content through the overexpression of a key gene.

In order to exploit the potential applications of graphene as gas sensors, the adsorptions of a series of small gas molecules (such as CO, O2, NO2 and H2O) on pristine graphene (PG) and Si-doped graphene (SiG) have been investigated by ab initio calculations. Our results indicate that the electronic properties of PG are sensitive to O2 and NO2 molecules, but not changed much by the adsorption of CO and H2O molecules. Compared with PG, SiG is much more reactive in the adsorption of CO, O2, NO2 and H2O. The strong interactions between SiG and the adsorbed molecules induce dramatic changes to the electronic properties of SiG. Therefore, we suggest that SiG could be a good gas sensor for CO, O2, NO2 and H2O.

A 17-kDa water-soluble polysaccharide (PB) was isolated and purified from Phellinus baumii using the DEAE-Sephadex A-50 and LPLC-Sephadex G-75 methods. Exposure of RAW264.7 macrophages to PB resulted in a significant increase of the cellular proliferation rate, nitric oxide production and expression levels of the IL-1β, IL-18, IL-6, IL-12p35 and IL-12p40 genes. An MTT assay indicated that PB markedly suppressed the proliferation of HepG2 human liver cancer cells in a dose-dependent manner. Cell cycle analysis demonstrated that PB caused cell cycle arrest at the S phase, and 400 μg/ml of PB induced apoptotic cell death in HepG2 cells after 48 h. The results suggested that PB inhibited the proliferation of HepG2 cells by inducing cell cycle arrest at S phase, leading to apoptosis. In summary, our data indicate that the PB exerts immunoregulatory and anti-tumor activities in vitro.

Searching for the two-dimensional (2D) topological insulators (TIs) with large bulk band gaps is the key to achieve room-temperature quantum spin Hall effect (QSHE). Using first-principles calculations, we demonstrated that the recently-proposed antimonene [Zhang et al., Angew. Chem. Int. Ed. 54, 3112–3115 (2015)] can be tuned to a 2D TI by reducing the buckling height of the lattice which can be realized under tensile strain. The strain-driven band inversion in the vicinity of the Fermi level is responsible for the quantum phase transition. The buckled configuration of antimonene enables it to endure large tensile strain up to 18% and the resulted bulk band gap can be as large as 270 meV. The tunable bulk band gap makes antimonene a promising candidate material for achieving quantum spin Hall effect (QSH) at high temperatures which meets the requirement of future electronic devices with low power consumption.

Half-metallicity due to the coexistence of metallic nature for one spin component and insulating nature for the other is a base of spintronics devices, but was only achieved in few materials. From first-principles calculations, we demonstrate that a recently-synthesized two-dimensional organometallic framework of 1,3,5-tris(pyridyl)benzene and Cu atoms (Cu-TPyB) has robust half-metallicity. High electron velocity in one spin channel at Dirac point and a relatively large band gap in the other make the material meeting the demand of filtering the current into a single spin component. Moreover, spin-orbit coupling induces topologically nontrivial band gaps in the vicinity of the Fermi level, which are implementable for achieving quantum anomalous Hall effect in a low temperature range (

Systematic calculations of stopping power (SPs) and inelastic mean free path (IMFP) values for 20-20,000 eV electrons in a group of 15 amino acids and a simple protein have been performed. The calculations are based on the dielectric response model and take into account the exchange effect between the incident electron and target electrons. The optical energy-loss functions for the 15 investigated amino acids and the protein are evaluated by using an empirical approach, because of the lack of experimental optical data. For all the considered materials, the calculated mean ionization potentials are in good agreement with those given by Bragg's rule, and the evaluated SP values at 20 keV converge well to the Bethe-Bloch predictions. The data shown represent the first results of SP and IMFP, for these 15 amino acids and the protein in the energy range below 20 keV, and might be useful for studies of various radiation effects in these materials. In addition, the average energy deposited by inelastic scattering of the electrons on this group of 15 amino acids, on the protein, on Formvar and on DNA, respectively, has been estimated for energies below 20 keV. The dependences of the average energy deposition on the electron energy are given. These results are important for any detailed studies of radiation-induced inactivation of proteins and the DNA.

Systematic calculations of stopping powers (SPs) and mean free paths (MFPs) for 10 bioorganic compounds have been performed for electrons with energies lower than 10 keV, based on dielectric response theory and Penn’s statistical approximation. The exchange effect is also taken into account in the calculations. An empirical approach to obtain an optical energy loss function is presented for those organic compounds without available optical data. Using this method, the calculated values of the optical energy loss function are in good agreement with experimental data. Comparisons of SP and MFP values derived in this study with other published values are presented. Using the described model, the calculated mean ionization potentials agree well with the predictions from Bragg’s rule and the calculated SPs have also been compared with the Bethe–Bloch results at an energy of 10 keV.

Implanted-fluorine profiles in ITO films have been accurately measured using the 19F(p,αγ)16O resonance nuclear reaction at ER=872.1 keV, with width Γ=4.2 keV. A proper deconvolution calculation method was used to extract the true distribution of fluorine from the experimental excitation yield curves. The experimental range distribution parameters, Rp and ΔRp, were compared with those obtained from Monte Carlo simulation codes.

The cross sections of electron inelastic interaction in DNA are calculated using the dielectric response theory and Penn statistical approximation, with the exchange correction included. An empirical approach to obtain optical energy loss function is given for the organic compounds without available optical data. Comparisons of the calculated data with available experimental and theoretical results have been done to show the reliability of the approach proposed in this work. Using this approach, the total inelastic cross sections for five bases: guanine, adenine, thymine, cytosine and uracil have been calculated in the energy range of Eor =10 keV and compared with those recently obtained with the Deutsch-Mark formalism and the Binary-Encounter-Bethe model, respectively. An equivalent unit of the DNA molecule is constructed according to the contents of A-T and G-C base pairs in DNA, and is divided into five constituents, i.e. sugar-phosphate and four bases. The total inelastic cross sections for the constructed unit of the DNA molecule and its constituents have also been calculated.

Spin-polarized triangular graphene nanoflakes (t-GNFs) serve as ideal building blocks for the long-desired ferromagnetic graphene superlattices, but they are always assembled to planar structures which reduce its mechanical properties. Here, by joining t-GNFs in a spiral way, we propose one-dimensional graphene spirals (GSs) with superior mechanical properties and tunable electronic structures. We demonstrate theoretically the unique features of electron motion in the spiral lattice by means of first-principles calculations combined with a simple Hubbard model. Within a linear elastic deformation range, the GSs are nonmagnetic metals. When the axial tensile strain exceeds an ultimate strain, however, they convert to magnetic semiconductors with stable ferromagnetic ordering along the edges. Such strain-induced phase transition and tunable electron spin-polarization revealed in the GSs open a new avenue for spintronics devices.

Molecular-dynamics simulations (MDSs) and ab initiocalculations are used to investigate the adsorption behavior of C60 molecules on a clean dimer-reconstructed (100)(2×1) diamond surface. C60 molecules have some probability to be adsorbed on the diamond surface at low incident energy (6∼45 eV). Electron-density contours show strong chemical interaction between C60 molecules and the substrate surface. The adsorption property depends strongly on the incident energy and the impacting point. An incident energy of 18 eV may be an appropriate energy to grow a sub-monolayer or monolayer C60 film on a clean C(100)(2×1) surface at room temperature.

The spin memristive devices combining memristance and tunneling magnetoresistance have promising applications in multibit nonvolatile data storage and artificial neuronal computing. However, it is a great challenge for simultaneous realization of large memristance and magnetoresistance in one nanoscale junction, because it is very hard to find a proper spacer layer which not only serves as good insulating layer for tunneling magnetoresistance but also easily switches between high and low resistance states under electrical field. Here we firstly propose to use nanon composite barrier layers of CoO-ZnO to fabricate the spin memristive Co/CoO-ZnO/Co magnetic tunnel junctions. The bipolar resistance switching ratio is high up to 90 and the TMR ratio of the high resistance state gets to 8% at room temperature, which leads to three resistance states. The bipolar resistance switching is explained by the metal-insulator transition of CoO1−v layer due to the migration of oxygen ions between CoO1−v and ZnO1−v.

Graphene was the first material predicted to realize a topological insulator (TI), but unfortunately the gap is unobservably small due to carbon's weak spin-orbital coupling (SOC). Based on first-principles calculations, we propose a stable sp-sp(2) hybrid carbon network as a graphene analog whose electronic band structures in proximity of the Fermi level are characterized by Dirac cones. We demonstrate that this unique carbon framework has topologically nontrivial electronic structures with the Z2 topological invariant of v = 1 which is quite promising for hosting the quantum spin Hall effect (QSHE) in an experimentally accessible low temperature regime (7 K). This provides a viable approach for searching for new TIs in 2D carbon allotropes.

Range distributions for bismuth ions implanted in AgGaSe2 in the energy range 80–300 keV were investigated by using 2.1-MeV He2+ Rutherford backscattering spectrometry (RBS). A convolution calculation method was used to extract the true distributions of bismuth from the measured RBS spectra. The range distribution parameters, Rp and ΔRp, were obtained and compared with those obtained from Monte Carlo simulation. The experimental Rp values agree with the Monte Carlo simulation values very well, but the experimental ΔRp values are systematically larger than those from the theoretical simulation.

We demonstrate the effectiveness of an economical scheme that uses numerical basis sets in computations with SIESTA. The economical basis sets demonstrated, in which high-level double-zeta basis plus polarization orbitals (DZP) are applied only for atoms of strong electronegativity and metal atoms while a double-zeta basis is applied to the rest of the atoms of small proton-bound carboxylic acid clusters and sodium–organic compounds, predict correct geometric structures very close to those obtained using DZP for all atoms. The use of economical basis sets can save about 30–50% of the CPU time that is used for calculations with large basis sets. This study provides a general guideline for basis set selection in SIESTA computations of large systems.