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Switchgrass is a perennial herbaceous plant regarded as a biomass energy crop in the United States for its high adaptability and yield potential. Processing and handling of switchgrass particles are challenging due to the erratic mechanical and flow behavior originating from their intrinsic particulate properties. In this work, we present a bonded-sphere discrete element model designed specifically for switchgrass particles. The model simultaneously captures three key particulate features, i.e., fibrous particle shapes, a wide range of particle sizes, and particle deformability. Realistic yet computationally efficient particle shape templates are created based on the image analysis data of switchgrass specimens. A fitting procedure is proposed to ensure both the particle width and length distributions are captured, a unique requirement for fibrous particles. Two full-scale numerical models, i.e., a uniaxial compression model and a Schulze ring shear model, are developed using information from physical experiments. The model is calibrated using experimental data of chopped-small switchgrass specimens, and then, is validated using data of chopped-large specimens in both compression and ring-shear tests. Numerical results show that the numerical models capture bulk densities accurately (with an error of 3%) while slightly underestimate the bulk friction angle. Furthermore, an extensive sensitivity analysis reveals that (1) switchgrass particles with rougher edges (due to different processing techniques) exhibit a higher shear strength and a lower flowability; (2) stiffer particles yield a lower bulk density (up to 21% lower) compared to more deformable particles, indicating particle deformability should be incorporated when modeling biomass flow in a preprocessing system. • A bonded-sphere discrete element model designed specifically for switchgrass particles. • Fibrous particle shapes, particle sizes, and particle deformability are explicitly captured. • Realistic yet computationally efficient shape templates are developed based on image data. • Model is validated in both compression and Schulze ring shear tests. • Particle deformability significantly impacts bulk density. [ABSTRACT FROM AUTHOR]

Abstract: Unipolar resistive switching behavior has been investigated in Pt/Co3O4/Pt stacks. The resistance ratio of the high- and low- resistance states is over 5×103. The “ON/OFF” operation of the memory cells can be repeated more than 200 times at room temperature. The resistance of the two states can be kept for more than 16h without showing degradation. The temperature dependence of the resistance shows a metallic behavior at the low-resistance state, but a semiconductor-behavior at the high-resistance state. The mechanism responsible for the observed unipolar resistive switching behavior has been discussed. [ABSTRACT FROM AUTHOR]

• Ferromagnetic metallic NiFe is used as top electrode. • URS persists with a thin Al 2 O 3 layer insert between NiFe and NiO. • Ni conductive filament is confirmed by the observation of AMR. • Insert of Al 2 O 3 layer narrows the distribution of reset voltages. Noble metals are generally used as electrodes in resistive switching devices. In this work, ferromagnetic metallic NiFe is used as top electrode on NiO films, and stable unipolar resistive switching (URS) behavior has been observed after a forming process. By inserting a thin Al 2 O 3 layer between NiFe and NiO, URS persists with increasing the thickness of Al 2 O 3 layer up to 20 nm. The URS behavior can be attributed to the formation and rupture of metallic Ni filaments in NiO layer, which penetrate through the thin Al 2 O 3 layer, and have been confirmed by the observation of anisotropic magnetoresistance. With further increasing the thickness of Al 2 O 3 layer up to 30 nm, forming free bipolar resistive switching (BRS) behavior is observed, which is due to the oxygen vacancy accumulation and dissipation at the interface because the thick Al 2 O 3 layer blocks the penetration of Ni filaments. By inserting a thin Al 2 O 3 layer with thickness below 20 nm, the distribution of the reset voltages in URS is significantly narrowed. [ABSTRACT FROM AUTHOR]

Graphical abstract A high-intensity compact ultrasonic irradiation assisted technique results in novel hierarchically porous N-doped graphene microsheets (PNGTMSs) with a highly interconnected three-dimensional network nanostructure allowing well-dispersion of near-spherical Ni 2 P nanoflowers. High porosity and optimal thickness allow the whole volume of an isolated microsheet in PNGTMSs to be ion-accessible. Combined with good dispersion of Ni 2 P and rich exposed interfaces, the Ni 2 P-PNGTMSs composite shows higher specific capacitances and superior rate capability than most reported similar graphene-based composites. Asymmetric solid-state cell displays a high output voltage of 1.8 V and delivers high energy densities over those reported for similar devices as well as remarkable cycling stability. Highlights • Novel hierarchical PNGTMSs feature the advantages of both 2D and 3D graphene. • Achieved by a high-intensity compact ultrasound assisted technique. • New insights into ultrasonic activation are proposed. • Ni 2 P-PNGTMSs composite shows high capacity, superior rate capability and stability. • Asymmetric supercapacitor achieves high energy density and power densities. Abstract Severe restacking of single-atom-thick two-dimensional graphene and too long ion diffusion path in a thick three-dimensional porous graphene film are both main current problems limiting performance maximization of graphene as an energy storage material. Herein, we report an advance toward the design and fabrication of novel hierarchically porous N-doped graphene thin microsheets (PNGTMSs) with a honeycomb-like network structure allowing good dispersion of near-spherical Ni 2 P nanoflowers (NFs) by high-intensity compact ultrasound assisted technique. New insights into ultrasonic activation inducing a preferential self-assembly in a planar direction are proposed. High porosity and thin thickness of <500 nm allow the whole interior of isolated microsheets to be ion-accessible, which endows PNGTMSs with advantages of both two-dimensional and three-dimensional graphene as well as enhanced electrical conductivity. Combined with Ni 2 P nanosheet-built NFs and their good dispersion as well as rich exposed interfaces, Ni 2 P-PNGTMSs exhibits specific capacitance of 1100 F g−1 at 1.0 A g−1. Asymmetric solid-state device delivers an energy density of 39.8 Wh kg−1 (at 450.6 W kg−1) and remarkable cycling stability with 97% capacitance retention after 5000 charge-discharge cycles. This work provides a convenient and scalable strategy for control over graphene nanostructures and their composites for highly enhanced energy storage. [ABSTRACT FROM AUTHOR]

A nonvolatile memory structure with a high-k composite of ZnO-TiO2 as a charge-trapping dielectric was fabricated by using rf-sputtering and atomic layer deposition techniques, in which the potential of the conduction-band minimum of the composite was designed to be lower than that of Si by the use of the special energy-band offsets among Si, ZnO, and TiO2. Compared to the conduction-band minimum of Si, a relatively negative potential of the high-k composite leads to a continuous rise in the shift of the flat-band potential of the memory device except a drop at the beginning part of the time-dependent retention curve after a programming operation. The drop was attributed to the escape of trapped charges at the Si/Al2O3 interface. After extracting the contribution to the deterioration of the retention curve from the traps at the Si/Al2O3 interface, it was identified that the band alignment in a charge-trapping memory device dominated its retention behaviors. [ABSTRACT FROM AUTHOR]

[Display omitted] Nucleotide-binding oligomerization domain (NOD)-like receptor type 2 protein (NLRP2) was reported to inhibit NF-κB in response to inflammatory stimuli, but its role in tumors remains elusive. We screened out NLRP2 from mouse models of breast cancer metastasis. Bioinformatics analysis showed NLRP2 expression was positively correlated with survival rate and negatively correlated with the potential of cancer metastasis. Its significance in Triple-Negative Breast Cancer (TNBC) was investigated by gain- and loss-of-function studies in vivo and vitro. Re-expression of NLRP2 dramatically inhibited the growth and metastasis of the xenograft model of MDA-MB-231 cells. Mechanically, NLRP2 confined hnRNPK within cytoplasm, which in turn blocked vimentin mRNA production. Not only that, NLRP2 further enhanced the H 2 O 2 -induced high level of p53&Bax and hence dramatically increased the apoptosis rate (fivefold). Likewise, carboplatin-treated cells showed decreased cell viability, suggesting that patients of TNBC with high level of NLRP2 respond well to chemotherapeutics. Under the stimulus of H 2 O 2 , NLRP2–hnRNPK no longer stayed in the cytoplasm, but entered the nucleus to increase the expression of p53 and hence enhanced corresponding apoptosis effect, increasing Bax expression. It suggested that NLRP2 helps p53 enter the nucleus to induce apoptosis. This study revealed a novel function of NLRP2 that modulated oncogenic and anti-oncogenic characteristics of hnRNPK, and provided a new biomarker for TNBC chemotherapy. [ABSTRACT FROM AUTHOR]

Oxide-based binary resistive switching memories using metal nitride as one of the electrodes usually have a limited ratio of the resistances of the high- and low-resistance states. Here, we propose a competing mechanism to enhance the switching ratio by modifying the high-resistance state with extra inherent interfacial oxygen diffusion against what happens at the oxide/nitride interface. This is implemented in Pt/ZrO2/Ta2O5/TaN bilayer structures, where a resistance ratio above 104, about one to two orders of magnitude greater than that in Pt/Ta2O5/TaN monolayer structures, is achieved. This competing mechanism is further corroborated by the failed enhancement in the switching ratio when using an altered stacking arrangement of the two oxide layers. [ABSTRACT FROM AUTHOR]

Nanostructure engineering on the electrodes remains challenging for high-performance supercapacitors to meet the ever-increasing demands. Inspired by the function and structure of the loofah which possesses an inner firm skeleton coupled with the outer crisscrossed fibers, herein, a novel loofah-like core-shell nanostructure is synthesized with well-designed Co 0.6 Mn 0.4 Se nanowires dominated as the core, and MnO 2 nanoflakes decorated as the shell. The bimetallic selenide exhibits high conductivity and rich electrochemical activity owing to the coexisting metals component. It also serves as a robust support to hinder the agglomeration of MnO 2 nanoflakes, forming a unique porous structure with great ability of self-adapting to volumetric changes. The optimized Co 0.6 Mn 0.4 Se/MnO 2 electrode exhibits an ultrahigh areal capacity (3.91 F cm−2/0.60 mAh cm−2 at 2 mA cm−2) and an exceptional retention of 95.47 % after 8000 cycles. Both performances are superior to the MnCo 2 O 4 /MnO 2 electrode without the loofah-like networks in our work. Moreover, the assembled Co 0.6 Mn 0.4 Se/MnO 2 //AC (active carbon) hybrid supercapacitor delivers a high energy density of ∼89.67 Wh kg−1 at a power density of 399.98 W kg−1, and a remarkable life span with ∼97.30 % retention after 12,000 charge/discharge cycles. The eye-catching results indicate that the integrated Co 0.6 Mn 0.4 Se nanowires show great potential to engineering advanced electrodes. Further demonstration of the all-solid-state flexible cell based on the bio-inspired Co 0.6 Mn 0.4 Se/MnO 2 structure also proves its practical application in wearable electronics. • The loofah-like Co 0.6 Mn 0.4 Se/MnO 2 core-shell structure is synthesized. • The innovative bimetallic selenide serves as the outstanding core material. • The advanced cathode exhibits an extremely high areal capacity. • Asymmetric supercapacitor delivers high energy density and remarkable life span. [ABSTRACT FROM AUTHOR]

In this work, we used a simple co-solvent method to prepare large-sized freestanding PbI 2 single crystals by heating the solution. The obtained hexagonal slabs were confirmed as 2H-type PbI 2 single crystals with a band gap of 2.3 eV. Photo-detector employing such single crystal was demonstrated to show promising performances to 450 nm laser including great photo-switch current ratio (10 4 ), promotable responsivity (0.18 AW −1 ), external quantum efficiency (49.6%), specific detectivity (3.23 × 10 11 Jones) and fast (rise time of 323 μs and decay time of 520 μs), stable, switchable photo-response. These results substantiate the PbI 2 single crystals synthesized by such co-solvent method as promising candidates for optoelectronic applications. [ABSTRACT FROM AUTHOR]

Cosmogenic 10 Be surface-exposure dating and numerical glacier modeling are used to reconstruct glacial chronology and climate in the Colorado Sangre de Cristo Mountains during the local last glacial maximum (LLGM) and the subsequent deglaciation. Twenty-two surface-exposure ages on moraine boulders and polished-bedrock outcrops in the Willow Creek valley and ten in two adjacent valleys indicate that glaciers were at or near their maxima from ∼21 ka until 17–16 ka, and then retreated rapidly, nearly deglaciating the Willow Creek valley entirely by ∼14 ka. Coupled energy/mass-balance and flow modeling of two of the glaciers indicates that, if changing ice extent was driven only by temperature and insolation changes, temperature depressions of 5.0 and 5.1 °C from modern conditions, with an uncertainty of approximately + 1.5 / − 1.0 °C, would have sustained the glaciers in mass-balance equilibrium at their LLGM extents. Doubling or halving of modern precipitation during the LLGM would have been associated with 2.7–3.0 °C and 6.9–7.0 °C temperature depression respectively. Approximately half of the subsequent LLGM–to-modern climate change was accomplished by ∼14 ka. If the rapid main phase of deglaciation between about 16 ka and 14 ka was driven solely by temperature and insolation changes, it would have been associated with a temperature rise of about 2.5 °C, at a mean rate of approximately 1.1 °C/ky. This new chronology of the last glaciation is generally consistent with others developed recently in the Colorado Rocky Mountains. The numerical modeling, however, suggests a lesser LLGM temperature depression from modern conditions than have most previous studies in Colorado. [ABSTRACT FROM AUTHOR]

Lead-free (1− x )(0.0852Bi 0.5 Na 0.5 TiO 3 –0.12Bi 0.5 K 0.5 TiO 3 –0.028BaTiO 3 )– x CaZrO 3 piezoelectric ceramics (BNT−BKT−BT− x CZ, x =0, 0.01, 0.02, 0.03, 0.04 and 0.05) were prepared by using a conventional solid-state reaction method. The effects of CZ-doping on the structural, dielectric, ferroelectric and piezoelectric properties of the BNT−BKT−BT− x CZ system were systematically investigated. The polarization and strain behaviors indicated that the long-range ferroelectric order in the unmodified BNT−BKT−BT ceramics was disrupted by the increase of CZ-doping content, and correspondingly the depolarization temperature ( T d ) shifted down from 109 °C to below room temperature. When x >0.03, accompanied with the drastic decrease in the remnant polarization ( P r ) and piezoelectric coefficient ( d 33 ), the electric-field-induced strain was enhanced significantly. A large unipolar strain of 0.35% under an applied electric field of 70 kV/cm ( S max / E max =500 pm/V) was obtained in the BNT−BKT−BT−0.04CZ ceramics at room temperature, which was attributed to the reversible electric-field-induced phase transition between the relaxor and ferroelectric phases. [ABSTRACT FROM AUTHOR]

A new second-order accurate, hybrid, incremental projection method for time-dependent incompressible viscous flow is introduced in this paper. The hybrid finite-element/finite-volume discretization circumvents the well-known Ladyzhenskaya–Babuška–Brezzi conditions for stability, and does not require special treatment to filter pressure modes by either Rhie–Chow interpolation or by using a Petrov–Galerkin finite element formulation. The use of a co-velocity with a high-resolution advection method and a linearly consistent edge-based treatment of viscous/diffusive terms yields a robust algorithm for a broad spectrum of incompressible flows. The high-resolution advection method is shown to deliver second-order spatial convergence on mixed element topology meshes, and the implicit advective treatment significantly increases the stable time-step size. The algorithm is robust and extensible, permitting the incorporation of features such as porous media flow, RANS and LES turbulence models, and semi-/fully-implicit time stepping. A series of verification and validation problems are used to illustrate the convergence properties of the algorithm. The temporal stability properties are demonstrated on a range of problems with 2 ≤ C F L ≤ 100 . The new flow solver is built using the Hydra multiphysics toolkit. The Hydra toolkit is written in C++ and provides a rich suite of extensible and fully-parallel components that permit rapid application development, supports multiple discretization techniques, provides I/O interfaces, dynamic run-time load balancing and data migration, and interfaces to scalable popular linear solvers, e.g., in open-source packages such as HYPRE, PETSc, and Trilinos. [ABSTRACT FROM AUTHOR]

Two types of bipolar resistive switching (RS) model were revealed respectively, before and after electroforming in the α -Fe 2 O 3 films fabricated by ultrasonic spray pyrolysis on fluorine-doped SnO 2 conducting glass. The current-voltage curves of cell before and after electroforming were fitted. The conduction mechanism at high resistance state of the model before electroforming was attributed to Schottky emission, whereas after electroforming it can be explained by space-charge-limited conduction. These two types of RS model originate from interface and bulk effect, respectively. The retention of the cells with different RS models was studied comparatively and the possible mechanism was discussed. [ABSTRACT FROM AUTHOR]

Abstract: In virtue of the first-principle calculations, the hydrogen storage behavior in several metal decorated graphyne was investigated. It is found that the hydrogen storage capacity can be as large as 18.6, 10.5, 9.9 and 9.5 wt% with average adsorption energy of about −0.27, −0.36, −0.76 and −0.70 eV/H2 for Li, Ca, Sc, Ti decorated graphyne, respectively. The results suggest potential candidates for hydrogen storage at ambient condition. The adsorption mechanism for H2 on metal coated graphyne was mainly attributed to the polarization induced by electrostatic field of metal atoms on graphyne and the hybridization between the metal atoms and hydrogen molecules. Furthermore, the formation of super-molecules of hydrogen can enhance the adsorption energy. [Copyright &y& Elsevier]

Abstract: The phase change behavior of Ge2Sb2Te5 (GST) nanowires and nanotubes was investigated by using thermodynamic calculations. It is revealed that the melting and crystallization temperatures for both nanowires and nanotubes decrease as the diameter of the nanostructures is reduced. There exists a critical diameter for both nanowires and nanotubes, below which the crystallization could not take place. It determines the ultimate scaling limit of nanowires or nanostructures phase-change memory. The critical diameter for nanowires depends on the difference between the surface energy of solid and liquid phases, the bulk melting and crystallization temperatures, as well as the melting and crystallization entropy. The critical diameter of the nanotubes is larger than that of the nanowires. And it is also dependent on the ratio of outer diameter over inner diameter of the tubes. The lower ratio of outer diameter over inner diameter gives rise to the larger critical diameter of the nanotubes. [Copyright &y& Elsevier]

Abstract: The charge trap flash memory cells incorporating high-k ZrO2/Al2O3 nanolaminate as charge trapping layers and amorphous Al2O3 as tunneling and blocking layers were prepared, investigated and optimized. The interfaces between ZrO2/Al2O3 nanolaminate play an important role in the charge storage characteristics. With increasing number of the interfaces in the charge trapping layer, the memory window increases first and then decreases due to electrostatic repulsion between the trapped electrons. A satisfactory retention performance was observed in the optimized cell structure, which was attributed to the deep quantum wells between the ZrO2/Al2O3 nanolaminate. [Copyright &y& Elsevier]

ZrO nanocrystallites based charge trap memory cells by incorporating a (ZrO)(SiO) film as a charge trapping layer and amorphous AlO as tunneling and blocking layer were prepared and investigated. The precipitation reaction in charge trapping layer forming ZrO nanocrystallites during rapid thermal annealing was investigated by transmission electron microscopy. The density and size of ZrO nanocrystallites are the critical factors for controlling the charge storage characteristics. The ZrO nanocrystallites based memory cells after postannealing at 800 C for 60 s exhibit the best electrical characteristics and a low charge loss ∼5 % after 10 write/erase cycles operation. [ABSTRACT FROM AUTHOR]

Abstract: Charge trapping memory capacitors using (ZrO2)0.8(SiO2)0.2 film as charge trapping layer and amorphous Al2O3 as the tunneling layer and blocking layer were fabricated for nonvolatile semiconductor memory application. The ZrO2 nanocrystallites with a size of 3–5nm precipitated from amorphous (ZrO2)0.8(SiO2)0.2 during rapid thermal annealing at 800°C can serve as the storage nodes, with which a large hysteresis memory window of 7.5V at a sweeping gate voltage of 8V has been achieved. At 150°C bake temperature, the memory capacitor exhibited an excellent endurance up to 105 write/erase cycles, after which a small charge loss of about 12% was achieved. [Copyright &y& Elsevier]

Silicon is the cornerstone of electronics and photonics. In this context, almost all integrated devices derived from two-dimensional (2D) materials stay rooted in silicon technology. However, as the growth substrate, silicon has long been thought to be a hindrance for growing 2D materials through bottom-up methods that require high growth temperatures, and thus, indirect routes are usually considered instead. Although promising growth of large-area 2D materials on silicon has been demonstrated, the direct growth of single-crystalline materials using low-thermal-budget synthesis methods remains challenging. Here, we report the room-temperature growth of millimeter-scale single-crystal 2D metal halides on silicon substrates with a hydroxyl-terminated surface. Theoretical calculations reveal that the activation energy for surface diffusion can be reduced by an order of magnitude by terminating the surface with hydroxyl groups, from which on-silicon growth is greatly facilitated at room temperature and enables a 4-order-of-magnitude increase in area. The high quality and uniformity of the resulting single crystals are further evidenced. The optoelectronic devices employing the as-grown materials show an ultralow dark current of 10 -13 A and a high detectivity of 10 13 Jones, thereby corroborating a weak-light detection ability. These results would point to a rich space of surface modulation that can be used to surmount current limitations and demonstrate a promising strategy for growing 2D materials directly on silicon at room temperature to produce large single crystals.

Waterflooding is one of the geotechniques used to recover fuel sources from nanoporous geological formations. The scientific understanding of the process that involves the multiphase flow of nanoconfined fluids, however, has lagged, mainly due to the complex nanopore geometries and chemical compositions. To enable the benchmarked flow of nanoconfined fluids, architected geomaterials, such as synthesized mesoporous silica with tunable pore shapes and surface chemical properties, are used for designing and conducting experiments and simulations. This work uses a modified many-body dissipative particle dynamics (mDPD) model with accurately calibrated parameters to perform parametric flow simulations for studying the influences of waterflooding-driven power, pore shape, surface roughness, and surface wettability on the multiphase flow in heptane-saturated silica nanochannels. Remarkably, up to an 80% reduction in the effective permeability is found for water-driven heptane flow in a baseline 4.5-nm-wide slit channel when compared with the Hagen-Poiseuille equation. In the 4.5-nm-wide channels with architected surface roughness, the flow rate is found to be either higher or lower than the baseline case, depending on the shape and size of cross sections. High wettability of the solid surface by water is essential for achieving a high recovery of heptane, regardless of surface roughness. When the solid surface is less wetting or nonwetting to water, the existence of an optimal waterflooding-driven power is found to allow for the highest possible recovery. A detailed analysis of the evolution of the transient water-heptane interface in those nanochannels is presented to elucidate the underlying mechanisms that impact or dictate the multiphase flow behaviors.

Sintered agglomerate of synthetic mesoporous silica nanoparticles (MSNs) is an architected geomaterial that provides confinement-mediated flow and transport properties of fluids needed for environmental research such as geological subsurface energy storage or carbon capture. The design of those properties can be guided by numerical simulations but is hindered by the lack of method to characterize the permeable pores within MSNs due to pore size. This work uses the advances of an Individual Particle cryogenic transmission Electron Tomography (IPET) technique to obtain detailed 3D morphology of monodispersed MSNs with diameters below 50 nm. The 3D reconstructed density-maps show the diameters of those MSNs vary from 35-46 nm, containing connected intraparticle pores in diameter of 2-20 nm with a mean of 9.2 ± 3 nm, which is comparable to the mean interparticle pore diameters in sintered agglomerate. The characterization of the pore shape and dimensions provides key information for estimating the flow and transport properties of fluids within the sintered agglomerate of those MSNs and for modeling the atomic MSN structures needed for pore-fluid simulations., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A modified many-body dissipative particle dynamics (mDPD) model is rigorously calibrated to achieve realistic fluid-fluid/solid interphase properties and applied for mesoscale flow simulations to elucidate the transport mechanisms of heptane liquid and water, respectively, through pore networks formed by packed silica nanoparticles with a uniform diameter of 30 nm. Two million CPU core hours were used to complete the simulation studies. Results show reduction of permeability by 54-64% in heptane flow and by 88-91% in water flow, respectively, compared to the Kozeny-Carman equation. In these nanopores, a large portion of the fluids are in the near-wall regions and thus not mobile due to the confinement effect, resulting in reduced hydraulic conductivity. Moreover, intense oscillations in the calculated flow velocities also indicate the confinement effect that contests the external driven force to flow. The generic form of Darcy's law is considered valid for flow through homogeneous nanopore networks, while permeability depends collectively on pore size and surface wettability. This fluid-permeability dependency is unique to flow in nanopores. In addition, potential dependence of permeability on pore connectivity is observed when the porosity remains the same in different core specimens.

The phase behavior of hydrocarbon fluids confined in porous media has been reported to deviate significantly from that in the bulk environment due to the existence of sub-10 nm pores. Though experiments and simulations have measured the bubble/dew points and sorption isotherms of hydrocarbons confined in both natural and synthetic nanopores, the confinement effects in terms of the strength of fluid-pore interactions tuned by surface wettability and chemistry have received comparably less discussion. More importantly, the underlying physics of confinement-induced phenomena remain obfuscated. In this work, we studied the phase behavior and capillary condensation of n -hexane to understand the effects of confinement at the molecular level. To systematically investigate the pore effects, we constructed two types of wall confinements; one is a structureless virtual wall described by the Steele potential and the other one is an all-atom amorphous silica structure with surface modified by hydroxyl groups. Our numerical results demonstrated the importance of fluid-pore interaction, pore size, and pore morphology effects in mediating the pressure-volume-temperature (PVT) properties of hydrocarbons. The most remarkable finding of this work was that the saturation pressure predicted from the van der Waals-type adsorption isothermal loop could be elevated or suppressed relative to the bulk phase, as illustrated in the graphical abstract. As the surface energy (i.e., fluid-pore interaction) decreased, the isothermal vapor pressure increased, indicating a greater preference for the fluid to exist in the vapor state. Sufficient reduction of the fluid-pore interactions could even elevate the vapor pressure above that of the bulk fluid.

With structural miniaturization down to the nanoscale, some detectable parameters of materials no longer remain constant. For NiO nanoparticles example, Raman shift and Néel temperature increase while optical band gap decreases with increasing the nanoparticle size. Herein, we developed the analytic models to describe the size dependence of these above-mentioned seemingly uncorrelated parameters for NiO nanoparticles, based on the average coordination number-dependent cohesive energy model. Consistency between our theoretical predictions and the corresponding experimental results not only verified the accuracy of our developed models but also provided insight into the essentiality of cohesive energy in describing the effect of size on the materials properties of NiO nanoparticles.

The magnetism of hole doped 1T-MX 2 (M = Zr, Hf; X = S, Se) monolayers is systematically studied by using first principles density functional calculations. The pristine 1T-MX 2 monolayers are semiconductors with nonmagnetic ground states, which can be transformed to ferromagnetic states by the approach of hole doping. For the unstrained monolayers, the spontaneous magnetization appears once above the critical hole density (10 14 cm -2 ), where the p orbital of S or Se atoms contributes the most of the magnetic moment. As the tensile strains exceed 4%, the magnetic moments per hole of ZrS 2 and HfS 2 monolayers increase sharply to a saturated value with increasing hole density, implying obvious advantages over the unstrained monolayers. The phonon dispersion calculations for the strained ZrS 2 and HfS 2 monolayers indicate that they can keep the dynamical stability by hole doping. Furthermore, we propose that the fluorine atom modified ZrS 2 monolayer could obtain stable ferromagnetism. The magnetism in hole doped 1T-MX 2 (M = Zr, Hf; X = S, Se) monolayers has great potential for developing spintronic devices with desirable applications., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Bismuth triiodide, BiI 3 , is one of the promising 2D layered materials from the family of metal halides. The unique electronic structure and properties make it an attractive material for the room-temperature gamma/X-ray detectors, high-efficiency photovoltaic absorbers, and Bi-based organic-inorganic hybrid perovskites. Other possibilities including optoelectronic devices and optical circuits are envisioned but rarely experimentally confirmed yet. Here, we report the synthesis of vertical 2D BiI 3 nanoplates using the physical vapor deposition mechanism. The obtained products were found easy to be separated and transferred to other substrates. Photodetectors employing such 2D nanoplates on polyethylene terephthalate substrate are demonstrated to be quite sensitive to red light (635 nm) with good responsivity (2.8 A W -1 ), fast stable photoresponse (3/9 ms for raise/decay times), and remarkable specific detectivity (1.2 × 10 12 jones), which attest to high comparability of the assembled components with many latest 2D nanostructured light sensors. In addition, such photodetectors exhibit outstanding mechanical stability and durability under different bending strains within the theoretically affordable levels, suggesting a variety of potential applications of 2D BiI 3 for flexible devices.

We propose a two-dimensional (2D) tetragonal material: an yttrium nitride (t-YN) monolayer, with a distinguished combination of mechanical and electronic properties based on first-principles calculations. We find that the t-YN monolayer is a low direct band gap semiconductor (0.55 eV) with strong anisotropic mechanical and electronic properties. We also identify that the t-YN monolayer to be a 2D ferroelastic material with a reversible strain of about 14.4%, indicating that the anisotropic properties of the t-YN monolayer can be switched by applying external stress. Furthermore, the moderate-switching barrier (33 meV/atom) of ferroelastic lattice rotation renders the switchable anisotropic properties accessible experimentally. These outstanding properties make the t-YN monolayer a promising switchable anisotropic 2D material for electronic and mechanical applications.

Using first-principles calculations, we designed a two-dimensional material, monolayer AgBiP 2 Se 6 , with the thickness of only 6 Å, which exhibited out-plane ferroelectricity. The ground state of the monolayer AgBiP 2 Se 6 was not purely ferroelectric since the out-plane ferroelectricity originated from the compensated ferrielectric state: the off-centering antiparallel displacements of Ag + and Bi 3+ ions. The compensated ferrielectric ordering has superiority on reducing the depolarization field to stabilize the ferroelectricity. Furthermore, together with strong visible-light adsorption and suitable band edge alignments, we proposed the monolayer AgBiP 2 Se 6 as a visible-light photocatalyst for water-splitting as the out-plane polarization could enhance the electron-hole separation. Our results offer a new way to overcome the critical thickness limitation of nanoscale ferroelectrics. The out-plane ferroelectricity in monolayer AgBiP 2 Se 6 has great potential for developing various devices with desirable applications.

By first-principles calculations, the magnetism of hole doped tin dichalcogenides SnX 2 (X = S, Se) monolayers is systematically studied. It is found that a phase transition from nonmagnetic to ferromagnetic ground state appears once above the critical hole density (~10 14  cm -2 ). The spin magnetic moment can maintain a magnitude of 1.0 μ B /hole with excellent stability of ferromagnetic state. Furthermore, we demonstrate that strain is very useful to modulate the DOS near the valence band, resulting in the reduction of the critical hole density to ~10 13  cm -2 when the strain reaches 4% (6%) in SnS 2 (SnSe 2 ), which can be realized in common field effect transistors. Moreover, the phonon dispersion calculations for the strained SnX 2 monolayers indicate that they can keep the dynamical stability under the hole doping. Therefore, the strain tunable magnetic transition in hole doped tin dichalcogenides indicates their potential promising applications in spintronic devices.

The structural and optical characterizations of titania incorporated with alumina nanocrystals have been presented in this paper and the films exhibit excellent properties like low current density, small hysteresis as well as high photoluminescence quantum yields of about 361 nm. These properties are promising for the applications in future electronic devices.