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Lithium-sulfur (Li-S) batteries with high theoretical specific energy of 2600 Wh kg–1 are one of promising candidates for next-generation energy storage devices. However, the severe shuttle effect of intermediate polysulfides leads to rapid capacity decay during battery cycling, especially at high sulfur loading and high current density. Herein, the MnO nanoparticles covered carbon with endoplasmic-reticulum-like structure (MnO@ERC) as separator coating for Li-S batteries is proposed. The MnO@ERC coating can act as upper current collector to enhance electrical conductivity of cathode and decrease the interface impedance of the whole battery. More importantly, both the polar MnO nanoparticles and Mn3O4 formed at the end of the charging process can catalyze the conversion of lithium polysulfides, which is convinced by the high adsorption energy and the elongate S–S bond. As a result, Li-S batteries based on MnO@ERC coating separator showed stable cycle for 350 cycles under 0.5 C, high discharge specific capacity of 783.6 mAh g–1 after 100 cycles at 0.2 C, 534.7 mAh g–1 after 100 cycles under the sulfur loading of 5.26 mg cm–2 and low self-discharge rate of 9.1% after resting 48 h.

Layered porous SiO2 (V-SiO2) was designed and prepared from vermiculite by expansion-acidification method, and then used as a catalyst support to prepare Ni/V-SiO2 for dry reforming of methane. It is well known that sintering and carbon deposition of metal particles are two main problems in deactivation of nickel-based catalysts for methane dry reforming. It is reported that strong metal support interaction is a possible solution. Here, a Ni/V-SiO2-H catalyst derived from Ni-phyllosilicate was developed, and compared with the catalyst Ni/V-SiO2-IM by impregnation method. The results showed that the Ni/V-SiO2-H catalyst had high catalytic activity and stability, and the CH4 conversion reached 71.7% at 700 �C. The reason is that on the one hand, the active metal particles in the catalyst are small (8.3 nm) and relatively evenly dispersed; on the other hand, the catalyst has strong metal support interaction, which improves the anti sintering ability of the catalyst and affects the catalytic activity. It is considered that V-SiO2 as a catalyst support for the preparation of Ni-phyllosilicate may have wide application.

In recent years, photoelectrocatalysis has been one of the hotspots of research. Graphite-like carbon nitride (g-C3N4) is one of the few non-metal semiconductors known and has good potential in the field of photocatalysis due to its simple preparation method and visible light effects. In this study, a method for compounding two semiconductor materials, In2S3 and Bi2S3, on the surface of g-C3N4 via a one-step hydrothermal method is reported, and it was found that this resulting material showed remarkable properties. The advantages of this method are as follows: (1) the formation of a heterojunction, which accelerates the separation efficiency of photogenerated carriers; (2) a large number of holes and defects on the surface of g-C3N4 are conducive to the nucleation, crystallisation and growth of In2S3 and Bi2S3. Compared with its counterpart catalysts, the CN/In2S3/Bi2S3 composite catalyst has significantly improved performance. Due to its high degree of crystallinity, the adsorption capacity of the catalyst itself is also significantly improved. In addition, the stability of the composite material maintains 90.9% after four cycles of use, and the structure is not damaged. In summary, CN/Bi2S3/In2S3 composite materials are believed to have broad application potential in the treatment of dye wastewater.

Sulfurized polyacrylonitrile (SPAN) is a promising cathode material for stable lithium–sulfur (Li–S) batteries due to its shuttle-free redox mechanism. However, the redox kinetics of SPAN needs to be enhanced to improve Li–S batteries. Herein, a salt-templating method is proposed for the fabrication of ultrathin SPAN nanosheets, which can afford a large contact area with the electrolyte and shorten the transport paths of electrons/ions involved in the reaction. In situ Raman analysis confirms the reversible breaking and formation of C–S/S–S bonds in SPAN nanosheets during cycling while ex situ SEM reveals the formation of lithium sulfide particles on the surface of SPAN nanosheets at the end of discharge. At a high current density of 2 A g−1, coin cells based on a SPAN nanosheet cathode can deliver a reversible capacity of 408 mA h g−1composite over 100 cycles with a capacity retention rate of 95%. Meanwhile, pouch cells using a SPAN nanosheet cathode exhibit a capacity retention rate close to 100% after 100 cycles at the same current density. These results herald a new approach for powering Li–S batteries by the nanoscale design of the SPAN cathode.

Diamond micro/nano-pillar is widely applied in quantum transportation and nanomechanics, but it is very difficult to be machined by conventional mechanical methods, duo to its feature of high hardness, wear-proof and extremely small scale. Thus, a novel strategy of galvanometer-assisted femtosecond laser milling (GFM) was proposed to overcome the difficulty of fabricating the micro-pillar with high aspect ratio on monocrystalline diamond. Through numeric calculation, it is found that GFM trajectory possesses the special distribution consisting of separate pulse-concentrated regions and expanded flat-distributed region, which was then experimentally proved beneficial for improving the energy consumption and highly promoting the material removal rate. Moreover, the GFM was found to be much easier to generate micro-pillar, whereas in the case of conventional non-galvanometer milling (NGM) micro-pillar underwent severe degeneration or height loss under various average laser powers. Through optimizing the machining parameters, the micro-pillar was successfully prepared with an aspect ratio of as high as 42.25 by GFM. A 5 × 5 micro-pillar array of monocrystalline diamond was also fabricated with consistent diameter, height and aspect ratio. With Raman spectroscopy, the graphitization induced by GFM was slight, though it was unavoidably introduced with relatively high average laser power. Besides, the graphitizing level on the lateral face of the machined micro-pillar was found to non-linearly change with different machining parameters, because the material removal mode underwent a transformation from graphitization dominated to sublimation dominated with the increasing of applied energy density.

Geometrical confinement has a large impact on gas solubilities in nanoscale pores. This phenomenon is closely associated with heterogeneous catalysis, shale gas extraction, phase separation, etc. Whereas several experimental and theoretical studies have been conducted that provide meaningful insights into the over-solubility and under-solubility of different gases in confined solvents, the microscopic mechanism for regulating the gas solubility remains unclear. Here, we report a hybrid theoretical study for unraveling the regulation mechanism by combining classical density functional theory (CDFT) with machine learning (ML). Specifically, CDFT is employed to predict the solubility of argon in various solvents confined in nanopores of different types and pore widths, and these case studies then supply a valid training set to ML for further investigation. Finally, the dominant parameters that affect the gas solubility are identified, and a criterion is obtained to determine whether a confined gas-solvent system is enhance-beneficial or reduce-beneficial. Our findings provide theoretical guidance for predicting and regulating gas solubilities in nanopores. In addition, the hybrid method proposed in this work sets up a feasible platform for investigating complex interfacial systems with multiple controlling parameters.

Diffusion of ionic components in electrolytes not only eliminates the gradients of ionic concentrations but also alters the local dielectric environment, and the coupling effect between kinetic dielectric decrement and ionic concentration gradient on the diffusion dynamics is not well understood. Herein, taking the charging process in electrical double layer systems as a case study, we conduct a multiscale investigation of ion diffusions in aqueous electrolytes by combining the dynamic density functional theory and an ion-concentration-dependent dielectric constant model. By properly considering the time evolutions of local dielectric constant coupled with ion density, we report an interesting phenomenon on the suppression of surface charge density that is not captured by conventional models. In addition, we show that the usage of aqueous electrolyte with small dielectric decrement coefficients promotes the capacitance, in quantitative agreement with experimental measurements.

Development of next-generation high-energy lithium (Li) metal batteries is hindered by uncontrollable growth of Li dendrites and the unstable Li/electrolyte interface during repeated Li plating/stripping. To overcome these issues, artificial protection for Li metal prior to assembling the cell/battery is needed. Here we show a facile approach to in situ coating of a protected layer on the Li metal anode by directly placing a PVDF-HFP/AlF3 modified Celgard separator on its surface. We find that AlF3 can react with highly reactive Li metal and produce a LiF coating on Li metal in situ. This LiF-rich SEI layer can effectively passivate the highly active Li anode surface and suppress the lithium dendrite growth, forming a uniform structure on the Li/electrolyte interface that reduces interfacial impedance. Owing to the enhanced interface stability, the Li‖Li cell presents a stable polarization voltage for approximately 600 h compared with the blank cell (45 h). The Li‖LiFePO4 cell with the composite separator has a high capacity retention of 78.3% after 300 cycles at the 3C rate, exhibiting an improvement in the cycling life of high energy-density Li metal batteries.

N-Doped carbon nanotubes with embedded cobalt nanoparticles (Co-NCNTs) were prepared by thermally annealing a mixture of ZIF-67 and dicyandiamide precursors. Because of the dual chemical affinity of Co and N to S species, Li-S batteries with a Co-NCNT modified separator revealed enhanced redox kinetics of lithium polysulfide conversion and achieved a high areal capacity of 3.73 mA h cm-2 after 100 cycles at 0.1C at a sulfur loading of 4.3 mg cm-2.

Lithium (Li) metal is regarded as the most promising anode material for next-generation high energy density rechargeable batteries. However, the uncontrolled growth of Li dendrites and the infinite volume expansion of Li decrease the coulombic efficiency and cause safety concerns. One of the best strategies to solve these problems is engineering a nanostructured interface on the current collector. Thus, in the present paper, to regulate Li nucleation and suppress the growth of Li dendrites, metal-organic framework (MOF)-derived CuO nanorod arrays with lithiophilic groups were synthesized on a Cu foil current collector (CuO NAs/CF). The CuO nanorod arrays with the N-containing group in CuO NAs/CF not only acted as lithiophilic active sites to reduce the nucleation barrier to Li deposition, but also decreased the current density and homogenized the Li-ion flux distribution. The CuO NAs/CF electrode showed a high coulombic efficiency of 98% for more than 180 cycles at 1 mA cm-2 and excellent cycling stability with a low overpotential of 30 mV for 600 h in symmetric cells. Based on the Li-CuO NAs/CF composite anode, full cells with a LiFePO4 cathode showed improved cycling stability, small polarization, and flat voltage curves compared with the cells using a planar Cu current collector. This work provides a new strategy for designing MOF-derived materials for stable, dendrite-free lithium metal anodes.

Lithium-sulfur batteries have shown increasing promise for high energy densities and reduced costs. Facile sulfur loading techniques demonstrate a critical way to achieving high dispersions of sulfur in the host's matrix, improving conductivity and simultaneously decreasing the active mass loss from the cathode. Here we investigate the effect of sulfur loading methods on the electrochemical performance of porous carbon/sulfur composites containing approximately 70 wt% sulfur. Three different loading techniques are tested, including one-step molten sulfur impregnation (155°C), two-step molten sulfur impregnation (155°C + 300°C) and a sulfur organic solution impregnation, in which the entire microporous volume of carbon is filled by sulfur. It is found that the simple sulfur organic solution impregnation method is the most effective in enhancing the electrochemical performance of the hierarchical porous carbon/sulfur composite cathode in the lithium-sulfur battery system, due to the weaker interaction occurring between the sulfur and microporous carbon. Our work demonstrates the impact of sulfur loading method on the electrochemical performance of lithium-sulfur batteries, which offers new insights into the preparation technology of electrodes.

Emerging catalytic host for sulfur is an effective approach to breaking the limits of lithium-sulfur batteries for practical applications. Herein, the hydrangea-shaped Co

We demonstrate a simple and direct method to precisely characterize the optical beam shear angle of polarizing prisms. Applying nanometer localization analysis for determining the central positions of the two sheared spots with orthogonal polarizations, we show that it allows for resolving the shear angle beyond the optical diffraction limit. We use Nomarski prisms to verify our technique and obtain a resolution below 0.5 μ rad. Our method provides a stand-alone characterization of polarizing prisms with a high accuracy for many quantitative imaging technologies such as differential interference contrast microscopy.

Fluid transport through membrane has attracted broad interests in recent decades due to their close association with wide industrial applications. Whereas massive experimental and simulation studies have been reported, the molecular mechanisms of fluid transport in nanopores are still poorly understood. Herein, we report a non-equilibrium molecular dynamics (NEMD) simulation study for elaborating the confinement effect of water transport through carbon nanotube (CNT) membranes. By varying the tube flexibility, inner surface wettability and pore size distribution (PSD), the permeability of water flow characterized with the flux enhancement rate is extensively examined. In addition, the pore size effect and pore size distribution are carefully taken into account when evaluating the apparent water flux through CNT membranes. We show that these treatments allow us to predict the water flux in a satisfactory agreement with reported experimental measurements. This work provides a quantitative simulation model toward the rational design of high efficient membranes.

Lithium-sulfur batteries are attractive because of their high specific capacity and energy density, but issues with the polysulfide dissolution and shuttling intrinsically hinder their wide application. Here, hydroxylate multiwalled carbon nanotubes (MWCNT-OH) were grafted with a supramolecular polymer (heptakis(6-amino-6-deoxy)-β-cyclodextrin) to form a polysulfide-engulfing net, which was coated on a separator. Such a molecular microarray structure of a polymer can block the polysulfides and have biomimetic cellular behavior for engulfing polysulfides. The cavity (∼6 A) and functional groups of the supramolecular polymer can provide a dynamic structure for reversible adsorption of polysulfides while the conductive MWCNT-OH ensure fast electron transfer. The batteries with the modified separator exhibited excellent rate capacities (945.5 and 625.4 mA h g-1 at 2 C and 4 C rates, respectively). Especially, the high areal capacities of 5.86 and 7.2 mA h cm-2 achieved at S loadings of 4.5 and 6.0 mg cm-2 and good cycling stability after 200 cycles at 0.1 C can be obtained. This demonstrates a strategy of supramolecular polymer-grafted carbon for dynamic polysulfide adsorption toward advanced Li-S batteries.

To enhance the thermal stability of lithium-sulfur batteries, separators are coated by ethylene-vinyl acetate copolymer microspheres (EVAs) and the thermal response behavior of ethylene-vinyl acetate copolymer microspheres/polypropylene separator (EVAs/PP) in lithium-sulfur batteries are investigated. The EVAs have a suitable melting point and a fast kinetic rate of thermal reaction. Thermal safety tests show that the prepared EVAs/PP thermal shutdown separators can quickly respond to the temperature change inside the lithium-sulfur battery under overheating conditions (85 °C), forming an insulating layer to protect the lithium-sulfur battery from thermal runaway hazards. In addition, EVAs/PP thermal shutdown separators have excellent porosity and electrolyte wettability compared to commercial PP separators. Conventional electrochemical performance tests indicate that EVAs/PP thermal shutdown separators applied in lithium-sulfur batteries exhibit electrochemical performance almost similar to that of PP separators. Due to the simple preparation and low cost, EVAs/PP thermal shutdown separator is expected to be a safe and excellent performance separator for lithium-sulfur battery applications.

Electrochemical two-electron oxygen reduction reaction (2e-ORR) offers a green route for production of hydrogen peroxide (H2O2). However, it remains a key challenge to design and develop the catalysts possessing both high activity and selectivity. Herein, we design ten Palladium-based single atom catalysts (Pd-based SACs) and report the underlying mechanisms of the activity and selectivity for 2e-ORR to produce H2O2. The intermediate of *OOH is used as a descriptor to describe the catalytic activity of 2e−/4e− ORR through a volcano diagram due to a linear scaling relationship between *OOH and *O (or *OH). We find that a defect graphene binding with one Pd single atom (C4Pd), which is thermodynamically favorable, exhibits an ultralow overpotential (0.044 V) for production of H2O2. In particular, this catalyst displays excellent activity and selectivity for H2O2 in a faintly acid or neutral electrolyte instead of alkaline. Furthermore, the Pd atomic clusters binding on defect graphene (C4Pdx, x = 2, 3, 4, 5) exhibit poor performance for production of H2O2 than that of C4Pd. The computational results reveal that the side-on adsorption configurations of O2 molecule and *H constitute the limiting factors for the selectivity of H2O2. These findings offer new insights for interpreting the mechanisms of 2e-ORR and pave the way for future designs and developments of excellent catalysts for the direct synthesis of H2O2.

The articular cartilage (AC) can be seen as a biphasic poroelastic material. The cartilage deformation under compression mainly leads to an interstitial fluid flow in the porous solid phase. In this paper, an analytical poroelastic model for the AC under laboratorial mechanical testing is developed. The solutions of interstitial fluid pressure and velocity are obtained. The results show the following facts. (i) Both the pressure and fluid velocity amplitudes are proportional to the strain loading amplitude. (ii) Both the amplitudes of pore fluid pressure and velocity in the AC depend more on the loading amplitude than on the frequency. Thus, in order to obtain the considerable fluid stimulus for the AC cell responses, the most effective way is to increase the loading amplitude rather than the frequency. (iii) Both the interstitial fluid pressure and velocity are strongly affected by permeability variations. This model can be used in experimental tests of the parameters of AC or other poroelastic materials, and in research of mechanotransduction and injury mechanism involved interstitial fluid flow.

Lithium metal is one of the most promising anode candidates for next-generation high-energy batteries. Nevertheless, lithium pulverization and associated loss of electrical contact remain significant challenges. Here, an antipulverization and high-continuity lithium metal anode comprising a small number of solid-state electrolyte (SSE) nanoparticles as conformal/sacrificial fillers and a copper (Cu) foil as the supporting current collector is reported. Guiding by the SSE, this new anode facilitates lithium nucleation, contributing to form a roundly shaped, micro-sized, and dendrite-free electrode during cycling, which effectively mitigates the lithium dendrite growth. The embedded Cu current collector in the hybrid anode not only reinforces the mechanical strength but also improves the efficient charge transfer among active lithium filaments, affording good electrode structural integrity and electrical continuity. As a result, this antipulverization and high-continuity lithium anode delivers a high average Coulombic efficiency of ≈99.6% for 300 cycles under a current density of 1 mA cm-2 . Lithium-sulfur batteries (elemental sulfur or sulfurized polyacrylonitrile cathodes) equipped with this anode show high-capacity retentions in their corresponding ether-based or carbonate-based electrolytes, respectively. This new electrode provides important insight into the design of electrodes that may experience large volume variation during operations.

Ultrahard nanotwinned diamond (nt-D) is an excellent diamond material with higher hardness, better fracture toughness and thermal stability than the commonly used single crystal diamond (SCD), thus it is considered as a promising tool material applied in ultra-precision cutting. However, extremely high hardness results in the fabrication of nt-D tool more difficult than SCD because of very low machining efficiency when using the conventional mechanical methods. Aiming to mass-produce of nt-D tool, the femtosecond pulsed laser milling technique was applied, and the related phase transition mechanism was explored during processing nt-D. Then, a trochoidal trajectory was proposed to acquire high forming accuracy and sharp edge in this study. It is found that the cubic diamond within nt-D was transformed into amorphization directly rather than graphitization under laser processing, which is attributed to the enhanced phase stability for nt-D. Furthermore, the nt-D surface integrity processed by laser was mainly restricted by diamond falling-off pits dewetting from grain boundary. Then, an optimized trochoidal trajectory method was proved to effectively decrease the depth of the falling-off pits and improve the surface integrity by the aid of laser pulse delay. Through the distribution calculation of pulse overlapping with the deduced theoretical equations and processing parameters optimization of galvanometer rotation, an nt-D cutting tool was successfully fabricated with smooth surface and sharp cutting edge. Finally, the wear mechanism, wear resistance and cutting performance of the as-fabricated nt-D tool were explored through cutting testing of hard polycrystalline MgF2. The results supported that nt-D tool exhibits better wear resistance and cutting performance than nanograined polycrystalline diamond (NPD) tool.

Thermal resistance induced by imperfectly bonded interfaces is closely related to failure at small scales. In this work, a nonlocal Kapitza thermal resistance model is constructed based on peridynamics. An embedded discontinuity model is formulated to capture the temperature jump condition induced by the interfacial thermal resistance. The model inherits the nonlocality of peridynamics but also captures the key physics of the interfacial heat barrier. To overcome the efficiency bottleneck of peridynamics, an implicit numerical procedure is formulated for both steady-state and transient-state solutions. The model is verified with various numerical examples quantitatively and shows a good agreement with analytical solutions by the classical heat conduction theory. Overall speaking, the proposed model extends the application of peridynamics in modeling general interface behaviors and establishes a foundation for predicting thermal-induced interfacial failure problems.

Reaction-diffusion (RD) coupling lies in the heart of chemical engineering. Due to the inherent density inhomogeneity of interfacial systems, the existing continuum approaches for quantifying the coupling between reaction and diffusion do not translate into interfacial systems, which highlights the urgent need for developing new methods to describe the RD coupling at nanoscale. In this work, a dynamic reaction density functional theory (DRxDFT) is proposed by combining the classical dynamic DFT for describing reactant/product diffusion with the reaction collision theory for addressing chemical reaction. For demonstrating its applicability to interfacial systems, the DRxDFT is hereafter applied to investigate an irreversible model reaction A + 2B → 2C on a catalytic substrate, and the effects of temperature, substrate adsorption strength, reactant concentration, diffusion coefficient, and reaction activation energy on reaction efficiency are examined. The calculated results show that the enhancement of reaction efficiency weakly depends on the unilateral increase of reaction or diffusion rate, but is strongly determined by the incensement of the coupled degree of reaction and diffusion. The proposed theory provides a promising tool for guiding the optimization and intensification of interfacial RD processes.

Catalytic properties and degradation of Co 3 O 4 infiltrated La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 /Ce 0 . Gd 0.1 O 2 (LSCF/CGO) cathode with Ag current collectors have been studied in this work. By controlling the infiltration sequence and the distribution of Co 3 O 4 nanoparticles, we were able to distinguish the aging effects of LSCF/CGO composite cathode and Ag current collector contributed to the cathode’s performance. It was confirmed that the stability of the infiltrated cells was influenced by the stability of both LSCF/CGO cathode and the Ag current collector. The aging of Ag current collector was found to be a major detrimental factor of the cell degradation, significantly enlarging the ASR during aging. Such deterioration was found to be suppressed by Co 3 O 4 infiltration.

In-situ carbon dioxide (CO2) huff-‘n’-puff (ISCHP) is a promising enhanced-oil-recovery (EOR) technique that could overcome some major drawbacks associated with continuous CO2 flooding such as early CO2 breakthrough, high operation costs, and demand for CO2 source. The application in Jiangsu Oil Field triggered the augmentation of well productivity and indicated the preliminary potential of this technique. Our work is to establish a prediction model for gas generation and to examine the mechanisms of ISCHP/EOR through sandpack tests and reservoir simulation. A salt solution with surfactant additives was selected to be the gas-forming agent, the gas-generating performance was tested in a high-temperature/high-pressure reactor first, and a kinetics-derived equation for gas-volume prediction was then verified by use of the experimental results. The displacement performance and efficiency were determined with sandpack tests with three different concentrations of a gas-forming agent. A reservoir model of ISCHP was established and calibrated on the basis of the sandpack-test results and past-production observations of the candidate well. The sensitivity analysis on the main-operation parameters was conducted to determine the optimal scheme, including injected volume, concentration, and soaking time. The results indicate that gas volume predicted by the theoretical model is well-matched to experimental data of the gas-forming reaction, the sandpack test makes clear the synergy of CO2 and chemical flooding in ISCHP, and a higher concentration of reagent tends to produce more oil than a lower one. Reservoir simulation shows a large amount of CO2 generated near the wellbore, an average growth of 61% in oil production, an regent usage of 0.91 ton/ton of oil, and a temperature decline of 2.5°C in the region of 20 m from the wellbore as a result of the endothermic reaction of reagent. On the basis of the reservoir model, the optimal scheme is achieved with a reagent concentration 16.4 wt%, an injected volume of 250 tons, and a soaking time of 7 days. This study can provide an improved understanding of ISCHP for EOR in Jiangsu Oil Field, including the gas-volume prediction, EOR potential in laboratory, and main operating parameters of ISCHP.

The behavior of two-dimensional (2D) materials for energy storage systems relates to their morphology and physicochemical properties. Although various 2D materials can be found in different fields, the open access of these materials has greatly hampered their practical applications, such as in lithium-sulfur (Li-S) batteries, where the soluble intermediates should be controlled. Here, we have developed a facile approach to prepare 2D ultrathin interconnected carbon fabrics (ICFs) with "bubble-like" morphology and abundant mesopores using a "blowing bubble" method. Serving as independent meso-sized rooms, nanosulfur dots can be stitched in 2D "bubble-like" ICF, which afford a short electron-/ion-transfer path and thus is beneficial to high reversible capacity. Encapsulated with reduced graphene oxide, a binder-free/free-standing cathode was constructed for advanced Li-S batteries. In addition, the specific energy of a pouch Li-S battery with this interconnected cathode can be achieved to 1.55 Ah@315.98 Wh/kg at 0.1 C. These results suggest that the design of "bubble-like" interconnected porous carbon fabrics and their integration with reduced graphene oxide provide a facile strategy to enhance the electrochemical activity of S and have the potential to be applied to other semiconductors or insulating materials for a wide range of applications.

N-doped hierarchical porous carbon was prepared by the carbonization of a polypyrrole precursor and activated using potassium hydroxide. The resulting carbon material has a specific area as high as 3271 m 2 g −1 and a hierarchical porous structure consisting of mixed parts microporous (

Hybrid carbon-coated transition metal oxides (TMOs@C) offer enhanced lithium storage capabilities, but the facile formation of TMOs@C nanocomposites remains a great challenge. Herein, we report a novel hierarchical hybrid nanostructure of carbon-coated CoFe2O4 twin elliptical frustums (CoFe2O4@C TEFs) via a quick one-pot refluxing reaction in ethylene glycol (EG) followed by an annealing treatment. When evaluated as an anode in lithium-ion batteries (LIBs), the resultant CoFe2O4@C TEF hybrids demonstrate good electrochemical performance with high reversible specific capacity, excellent rate capability and super-long life cycle. After 600 cycles at a current density of 500 mA g−1, the resultant TEFs still deliver a stable reversible discharge capacity of 875 mA h g−1. This work demonstrates the extensive potential of such simple synthetic methods towards various carbon coated transition metal oxide composites for energy conversion and storage devices.

High resolution light-sheet optical microscopy requires illuminating a sample by a thin excitation light sheet with large area. Here, we describe methods for producing light sheets with extended length, as compared to Gaussian-beam-type diffracting light sheets with the same thickness, without scanning or dithering the light beams., 8 pages, 3 figures

Novel binder-free, high capacity carbon-based anodes were manufactured using Virtual Cathode Deposition technique in an industrially scalable process. The deposition process transformed a commercial graphite target material into a novel carbon polymorph coating, which was used as Li-ion battery anode. Such anodes displayed first cycle specific capacity of ~1250 mAh g-1 and retained a capacity of more than 900 mAh g-1 at 0.1 C rate and more than 600 mAh g-1 at 0.5 A g-1 rate during cycling. Coulombic efficiencies above 99.5% were attained for 500 cycles. The anodes showed excellent volumetric (>1400 Ah L-1) and areal capacity (~4.5 mAh cm-2). Detailed structural characterisation revealed controllably induced packing polymorphism and high surface area (~2100 m2 g-1). The hierarchical architecture of the coatings was composed predominantly of meso- and macro-pores observed in a disordered carbon matrix encompassing nano-sized sp2-clusters (average size ~ 15–20 nm) cross-linked by a network of sp3-bonded atomic sites. A growth model based on the subsurface implantation mechanism was adopted to explain the formation of this unique structure responsible for the measured high specific capacity and good Coulombic efficiency.

Simultaneously integrating heterogeneous interface and element doping into BiOCl crystals is a promising strategy to promote the visible-light-driven photocatalytic activity. Here we demonstrated a facile solvothermal route for one-pot coupling Bi nanodots with Ta-doped BiOCl nanosheets (denoted as Ta-BiOCl/Bi). This Ta-BiOCl/Bi sample presented a remarkable catalytic performance toward the visible-light-driven degradation of Rhodamine B and tetracycline solution than those of the Ta-BiOCl, BiOCl/Bi and BiOCl photocatalysts. The enhanced photocatalytic mechanism can be proposed as follows. Both Ta dopant level in energy band structure of BiOCl and LSPR effect of Bi species were beneficial to increasing the visible light absorption, and the formation of heterogeneous interface between Ta-BiOCl and Bi was responsibility for accelerating the separation of charge carriers. This work might arouse in-depth investigations on the development of novel one-pot strategy for the synthesis of high-active BiOX (X = Cl, Br and I)-based photocatalysts.

We propose a new experimental mechanics method: dual beam-shear differential interference microscopy (DInM) for full-field surface deformation measurement. The method integrates the principles of differential interference contrast, photoelasticity, digital image correlation and the theories of continuum mechanics for a 4D quantification of the surface topography. Our first DInM prototype provides the lateral resolution of 787nm for up to 12% measurable out-of-plane strains. The resolution can be improved by using the shorter spectrum light and higher magnification objective lens. We use our system to characterize the buckling profile of Si microribbon on an elastomer substrate, which was verified by atomic force microscopy. We also demonstrate the stress-induced phase transformation in NiTi alloy by our system. The evolution of the surface topographies and the full-field deformation gradients are successfully captured and quantified. The dynamic measurement provides the information to calculate the relative transformation strains between phases of different symmetries. The establishment of dual beam-shear DInM opens a new avenue in the field of experimental meso/micromechanics.

T.Z. acknowledges the support of a Krishnan-Ang studentship from Trinity College, Cambridge. X.P., G.D., and C.D. acknowledge funding from ERC under Grant No. 259619 PHOTO EM. C.D. acknowledges financial support from the EU under Grant No. 312483 ESTEEM2. This work was also supported by the National Science Foundation of China (Grant No. 21373028), Major achievements Transformation Project for Central University in Beijing, and Beijing Science and Technology Project (Grant No. D151100003015001).

The rational construction of battery electrode architecture that offers both high energy and power densities on a gravimetric and volumetric basis is a critical concern but achieving this aim is beset by many fundamental and practical challenges. Here we report a new sea urchin-like NiCoO2@C composite electrode architecture composed of NiCoO2 nanosheets grown on hollow concave carbon disks. Such a unique structural design not only preserves all the advantages of hollow structures but also increases the packing density of the active materials. NiCoO2 nanosheets grown on carbon disks promote a high utilization of active materials in redox reactions by reducing the path length for Li+ ions and for electron transfer. Meanwhile, the hollow concave carbon not only reduces the volume change, but also improves the volumetric energy density of the entire composite electrode. As a result, the nanocomposites exhibit superior electrochemical performance measured in terms of high capacity/capacitance, stable cycling performance and good rate capability in both Li-ion battery and supercapacitor applications. Such nanostructured composite electrode may also have great potential for application in other electrochemical devices.

In Japan fly ash cement concrete is rarely used because its strength development is slow. This study aims to improve early age strength development of fly ash cement concrete using cement with increased C3S content up to 72% manufactured at an actual cement plant. Compressive strength, heat of cement hydration, autogenous shrinkage, drying shrinkage and shrinkage cracking tendency were investigated. Thermal cracking resistance was simulated using 3D FEM thermal stress analysis model. It was established that increasing C3S content in base cement improves early age strength, drying shrinkage cracking tendency and thermal cracking resistance of fly ash cement concrete.

The purpose of this experimental study is to evaluate the efficiency and performance of gas huff-n-puff in the single well on recovery of light oil from a multi-well fractured-cavity reservoir and to reveal the feasibility of gas mediums huff-n-puff. In order to reveal the production performance characteristics and mechanisms of gas huff-n-puff on activating the remaining oil, a visualized and pressure resistant two-dimensional (2D) fractured-cavity model and a three-dimensional (3D) multi-wells model were designed and fabricated respectively based on the similarity theory. With the simulated oil and brine reservoir samples in Tahe oilfield, five groups of tests in 3D model and five groups in 2D model were performed, each of which included bottom water energy depletion driving, gas injection stage, soaking stage, and gas puff stage. The production performances of N2, CO2, and N2/CO2 mixture huff-n-puff in the 3D model were firstly analyzed. Then the remaining oil recovery principles of each gas were compared and analyzed in the 2D model. Finally, the influence of gas injection position was studied both in the 2D and 3D models. The experiment results from 3D model demonstrated that higher oil recovery factor could be achieved through N2 huff-n-puff which had shown enormous advantages than CO2 and N2/CO2 mixture. Furthermore, the results from 2D model indicated that there were four types of the remaining oil, all of which could be recovered through N2 huff-n-puff if it was implemented in the relative low-position well. The results from experiments on gas injection position conducted in the 3D physical model demonstrated the better oil recovery effect if N2 was injected in low-position well which was consistent with the results concluded in the 2D model. This paper confirmed the effectiveness and advantages of N2 huff-n-puff compared with CO2 and gas mixture in the light oil-saturated fractured-cavity reservoir.

The depletion force exerted on an alkane molecule from surrounding solvent may greatly alter its conformation. Such a behavior is closely related to the selective molecular recognition, molecular sensors, self-assembly, and so on. Herein, we report a multiscale theoretical study on the conformational change of a single alkane molecule confined in water-filled cavitands, in which the quantum and classical density functional theories (DFTs) are combined to determine the grand potential of alkane-water system. Specifically, the intrinsic free energy of the alkane molecule is tackled by quantum DFT, while the solvent effect arising from the solvent density inhomogeneity in confined space is addressed by classical DFT. By varying the alkane chain length, pore size, and wettability of inner pore surface, we find that pore confinement and hydrophilic inner surface facilitate the alkane conformational change from extended state to helical state, which becomes more significant as the alkane chain length increases. Our findings, which are in line with previous experimental observations, provide not only the microscopic mechanism but also theoretical guidance for elaborately manipulating molecular conformation at the nanoscale.

Multi-layered dielectric structures are widely seen in modern semiconductor industry. Their applications cover multi-scaled areas such as in chips, packagings and printed circuit boards. Effective medium modeling for these structures enables fast yet accurate analysis so that the computational cost are reduced dramatically. In this dissertation, the numerical modeling techniques and experimental validations are explored for a general multilayer dielectric with periodic inclusions structure. The effective medium model based on the same reflection and transmission coefficients is introduced. The extraction procedure for effective constitutive parameters is described in detail. The branch cut issue in extraction procedure is examined and the solutions are provided so that the results are physically reasonable. Expressions of effective permittivity and permeability are given for both normal and oblique incidence, parallel and perpendicular polarizations. Analytical forms for low frequency limits of effective parameters are derived and numerical simulations are provided to verify the results. Based on the summary of Maxwell-Garnett mixing rule (MG formula), the asymptotic forms for the frequency dependent term in MG formula is derived. Then the transition of periodic dielectric to periodic metal objects is studied. Numerical results are presented to verify the transition. A multi-effective layer model is also evaluated. And the numerical results show that under certain conditions this model achieves better accuracy than simple MG formula. To validated our numerical modeling approach, experimental tests are performed. Using standard 4 layer printed circuit boards (PCB) technology, we are able to build periodic metal patches embedded in multi-layered dielectric. Different testing structures such as parallel plate capacitors and micro-strip with de-embedding structures are fabricated and measured. We’ve

We describe the apparatus of a fluorescence optical microscope with both single-photon and two-photon non-diffracting light sheets excitation for large volume imaging. With special design to accommodate two different wavelength ranges (visible: 400-700 nm, and near infrared: 800-1200 nm), we combine the line-Bessel sheet (LBS, for single-photon excitation) and the scanning Bessel beam (SBB, for two-photon excitation) light sheet together in a single microscope setup. For a transparent thin sample where the scattering can be ignored, the LBS single-photon excitation is the optimal imaging solution. When the light scattering becomes significant for a deep-cell or deep-tissue imaging, we use SBB light-sheet two-photon excitation with a longer wavelength. We achieved nearly identical lateral/axial resolution of about 350/270 nm for both imagings. This integrated light-sheet microscope may have a wide application for live-cell and live-tissue three-dimensional high-speed imaging., 4 pages, 5 figures

A novel carbon/sulfur composite has been fabricated by means of thermal and hydro-thermal treatments to serve as the cathode in Li–S batteries. The carbon matrix consists of graphene nanosheet (GS) and multiwalled carbon nanotube (MWCNT). The “GS/MWCNT@S” composite allows for infiltration of electrolyte into the cathode, assists in entrapment of polysulfide intermediates, and accommodates some of the stress and volume expansion that occurs during charge–discharge processes. In addition, the uniform distribution of sulfur in the conductive carbon matrix promotes utilization of the active materials. A Li–S cell containing the GS/MWCNT@S cathode delivered a capacity of 1290.8 mAh/g and exhibited stable specific capacities up to 612.1 mAh/g after 200 cycles at 0.1 C. These results demonstrate that this cathode material is a promising candidate for rechargeable lithium batteries with high energy density.

The purpose of this paper is to research an oil tolerant foam agent as a displacing phase to improve oil recovery in the fractured-vuggy carbonate reservoir. The foamability and foam stability were tested to optimize the concentrations of the foam compositions, and its static performance was analyzed in the presence of crude oil. Meanwhile, a visualized fractured-vuggy physical model was designed and fabricated based on the geological condition of well S48 and well TK467 in Tahe oilfield, West China. The residual oil type and distribution after bottom water flooding in the visualized model were firstly summarized. Secondly, dynamic production performances of N2 flooding and oil-tolerant N2 foam flooding were comparatively studied. Finally, the two primary factors including positional relation between injection-production wells and injection methods were primarily studied. Results indicate that the foamability and foam stability increase to a constant state when concentrations of surfactant and inorganic salt increase to 0.5 wt% and 0.35 wt%. And the polymer can significantly enhance the foam stability in the presence of oil. The displacing experiments in the model illustrate that the types of residual oil include oil trapped in the closed caves, "attic oil" on top of vugs, by-pass oil that can't be swept and oil film absorbed on the surface of fractures. The oil tolerant foam can stably accumulate in the vugs and expand swept volume due to gas mobility control. A better oil recovery can be achieved in foam injection by means of low positional flooding and high positional production. Besides, the oil recovery with slug foam injection is almost similar with continuous injection, but can significantly reduce the gas consumption.

Transition metal dichalcogenides (TMD), analogue of graphene, could form various dimensionalities. Similar to carbon, one-dimensional (1D) nanotube of TMD materials has wide application in hydrogen storage, Li-ion batteries, and supercapacitors due to their unique structure and properties. Here we demonstrate the feasibility of tungsten disulfide nanotubes (WS2-NTs)/graphene (GS) sandwich-type architecture as anode for lithium-ion batteries for the first time. The graphene-based hierarchical architecture plays vital roles in achieving fast electron/ion transfer, thus leading to good electrochemical performance. When evaluated as anode, WS2-NTs/GS hybrid could maintain a capacity of 318.6 mA/g over 500 cycles at a current density of 1A/g. Besides, the hybrid anode does not require any additional polymetric binder, conductive additives, or a separate metal current-collector. The relatively high density of this hybrid is beneficial for high capacity per unit volume. Those characteristics make it a potential anode material for light and high-performance lithium-ion batteries.

Lithium oxalyldifluoroborate (LiODFB) has been investigated as an organic electrolyte additive to improve the cycling performance of Li-S batteries. Cell test results demonstrate that an appropriate amount of LiODFB added into the electrolyte leads to a high Coulombic efficiency. Analyses by energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and the density functional theory showed that LiODFB promotes the formation of a LiF-rich passivation layer on the lithium metal surface, which not only blocks the polysulfide shuttle, but also stabilizes the lithium surface.

Li-S batteries have long been considered as one of the most potential candidates of novel multi-electron reaction system. Given the complete reaction of Li with S to form Li2S, Li-S batteries exhibit a theoretical specific capacity of 1675 mA h g-1 and energy density of ~2600 W h kg-1, which are much higher than those of state-of-the-art Li-ion batteries. In addition, S is naturally abundant with low environmental impact. However, wide applications of Li-S battery are hindered by many inherent problems. Here we review the recent advances in the cathode materials for high-specific-energy Li-S batteries.

During ultra-precision cutting of brittle materials, the wear of diamond tool seriously affects the quality of machined surface. By molecular dynamics modeling of nanometric cutting, the generation of graphitization and its formation process at the cutting edge of tool are observed. By analyzing the process, the reason of the graphitization wear is mainly thermo-chemical reactions. By calculating the changes of coordination numbers of the tool atoms, graphitization conversion rate keeps increasing along the cutting process but gets stable after a certain length, which indicates the graphitization wear will occur in the same process.

In this article, an accurate and efficient approach to model the multilayered dielectric with periodic metal inclusions is presented. The modeling combines effective medium theory and an efficient integral equation approach. Numerical results are provided to validate the accuracy and efficiency of this approach. Printed circuit board-based test structures are fabricated and measured to compare with the modeling results. Good agreements have been observed. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1387–1391, 2014