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The poor low-temperature performance of negative electrode materials— hydrogen storage alloys (HSAs) has impeded applications of nickel metal hydride batteries in new energy vehicles. Here, we propose a simple and effective strategy to improve low-temperature properties of the commercial HSA with HCl etching and heat treatment. The layered porous Ni surface structure formed during this process improves the electrochemical reaction kinetics, and thus results in a larger discharge capacity of 102.63 mAh g−1 at 233 K compared with those of bare (11.52 mAh g−1) and acid-corroded (43.00 mAh g−1) alloys. This method could be extended to enhance the low-temperature performance of other HSA systems.

Low intrinsic conductivity and large volume expansion seriously restrict the efficient lithium storage performance of metal sulfides. Here, we fabricate a hybrid material of NiS2 nanoparticles/carbon nanohelmets (NiS2/CNHs) to address the above issues. As an anode material in lithium-ion batteries, NiS2/CNHs exhibit excellent cycling stability (490 mA h g−1 after 3000 cycles at 5 A g−1) and rate properties (412 mA h g−1 at 10 A g−1), outperforming other NiSx-based anode materials. These remarkable performances originate from the three-dimensional helmet-like integrated architecture of NiS2/CNHs, which reduces the electrode resistance due to the tight combination between NiS2 and CNHs, provides efficient diffusion paths for the electrolyte and Li+ owing to the amorphous nanoporous carbon structure, and significantly mitigates the aggregation and buffers the large volumetric expansion of NiS2 nanoparticles upon long-term cycling thanks to the open three-dimensional architecture and well-dispersed NiS2 nanoparticles on it.

Traditional ground survey methods have limited the development and use of renewable energy from geothermal resources. In this paper, the geothermal potential area of Dandong, China is studied using the thermal infrared (TIR) remote sensing data from daytime Landsat 8 and nighttime Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). Through pre-processing such as georeferencing, radiometric calibration, and atmospheric correction, the Landsat8 TIRS and ASTER data were used to invert the land surface temperature of the study area during the daytime and nighttime using the single-channel algorithm and temperature and emissivity separation algorithm. Furthermore, the land surface temperatures during daytime and nighttime of three natural land features—water, vegetation, and bare soil—were classified and analyzed. According to the results, vegetation and bare soil show relatively thermal anomalies during the day and relatively cold anomalies during the night. Conversely, water shows relatively cold anomalies during the day and relatively thermal anomalies during the night. Calculating the daytime and nighttime mean of land surface temperature (DNMLST) can eliminate the relatively cold/thermal anomalies exhibited by natural land features during the daytime and nighttime while highlighting the geothermal anomaly zone. Nine geothermal anomaly zones were identified using the threshold method. The auxiliary analysis of geological data excluded non-geothermal effects. Studies have shown that the distribution of the identified geothermal prospects is consistent with the development and distribution of faults. The fractures cut the land surface, causing groundwater to form structural fissure hot water through fracture structures and fissures after magma heating. The use of two higher-resolution TIR remote sensing data products to obtain the DNMLST for the detection of geothermal anomalies has proven cost-effective technical method.

The ability to detect groundwater quickly and accurately is critical to the work of drought resistance. However, conventional groundwater detection methods are inefficient and costly. To solve the difficulties of using water in water-deficient areas, the method of rapid groundwater detection based on multidimensional space was presented. First, using satellite remote sensing (RS) technology, factors related to the occurrence of groundwater, such as lithology, structure, and landforms, were obtained. Then, through quantitative inversion of aeromagnetic data, the lithology and structure were improved. Using geographic information system (GIS) as an information analysis platform, the water storage conditions of various lithologies, structures, and landforms were comprehensively studied; and a water-rich target area was delineated. Based on the above-mentioned achievements, the ground geophysical prospecting work was carried out, the optimum well-position determined, and the target area accuracy verified by drilling data. The method integrates many technical means, such as satellite RS, airborne RS, ground physical exploration, and exploration drilling to detect groundwater, incorporating the advantages of each method. Through the preliminary application in the city of Beipiao, China, the well completion rate is 72.73%. High-quality groundwater resources were exploited in this area, proving it to be an effective method for accurately detecting groundwater.

Though high-capacitance transition metal oxides are considered as promising pseudocapacitive materials to achieve high-energy storage for supercapacitors, the practical capacitance is far from the theoretical values because of their intrinsic poor abilities about the electronic and ionic transports. Here, to tackle these problems, we develop a hybrid nanostructured electrode in a facile process, in which layer-structured δ-MnO2 nanosheets are anchored onto seamless three-dimensional Ni nanocylinder arrays. The resultant Ni/δ-MnO2 nanocylinder arrays exhibit high specific capacitance up to 883.2 Fg−1 at a scan rate of 10 mVs−1 and achieve high energy density about 108 Whkg−1 at a power of 2.4 kWkg−1. The improved electrochemical performance mainly benefits from the vertically aligned Ni/δ-MnO2 hybrid structure. Owing to such a hybrid structure the ion/electron transports are facilitated along the nanocylinders due to the reduction in the transport distance, and large accessible surface area is also provided for anchoring more high-capacitance materials. Moreover, the additional contact resistance can be dramatically reduced owing to the large interplanar spacing of δ-MnO2 and ordered semicoherent interface of Ni/δ-MnO2. Keywords: Supercapacitor, Hybrid electrode, Ni nanocylinder arrays, δ-MnO2, 3D nanostructure

The rapid development of catalysts requires a deep understanding of catalytic mechanisms. Since the experimental results have fallen short of the expectation of the optimal catalyst, the density functional theory (DFT) can provide invaluable mechanistic insights and predict promising catalysts. In this perspective, we briefly summarized the advantages of DFT in atomic and electronic structures for understanding electro-catalysis. Some achievements of DFT calculations were reviewed through some examples of the considered catalytic reactions (hydrogen evolution reaction, oxygen reduction reaction, nitrogen reduction reaction, and CO2 reduction reaction). Finally, we highlighted and analyzed the opportunities and challenges in DFT calculations used for electro-catalysis. On the road towards an optimal catalyst, the design of catalysts fused with DFT calculations promises rapid advances in the coming years.

The atomic dispersing of metal atoms supported on an optimal substrate exhibits an ideal strategy for maximizing metal utilization for catalysis, which is particularly significant for exploiting new catalysts with low cost and high catalytic efficiency. The dramatic development of atomic metal catalysts, including single atom catalysts (SACs), double atoms catalysts (DACs), and triple atoms catalysts (TACs), has spawned two remarkable platforms: (1) bridging homogeneous catalysts and heterogeneous catalysts; (2) linking theoretical calculations and experimental results. In this review, recent syntheses, characterizations, and applications of SACs, DACs, and TACs are highlighted through a focus on various applied substrates. We extensively discuss the synthetic strategies of successfully achieving SACs, DACs, and TACs. Moreover, the opportunities and challenges in developing SACs, DACs, and TACs are pointed out, together with the prospects for the development of atomic catalysis.

The pregnane X receptor (PXR) mediates the resistance of sorafenib in hepatocellular carcinoma (HCC) by promoting the clearance or elimination of sorafenib via the drug resistance-related downstream genes of the PXR. Previously, we revealed that rhamnetin (a flavonoid functioning as an inhibitor of sirtuin (Sirt)1) could inhibit expression of the downstream gene of the PXR: multidrug resistance 1 (mdr-1). However, how rhamnetin regulates the PXR pathway in HCC cells is not known. Here, we demonstrated that rhamnetin decelerated elimination of the molecular-targeting agent sorafenib in HCC cells via the microRNA (miR)-148a/PXR axis. Rhamnetin treatment decreased expression of the drug resistance-related downstream genes of PXR (cyp3a4 [cytochrome P-450] or mdr-1 [multi-drug resistance 1]), which mediate the metabolism or elimination of sorafenib in HCC cells. Mechanistically, rhamnetin increased expression of miR-148a (which is tumor-suppressive) in a P53-dependent manner, leading to inhibition of PXR expression and decrease in expression of its downstream genes. Rhamnetin enhanced miRNA-148a transcription by repressing Sirt1 activation to enhance acetylation at residue-373 of P53. Rhamnetin treatment decelerated the metabolic clearance of sorafenib in HCC cells and enhanced the sensitivity of HCC cells to sorafenib. Our results suggest that rhamnetin could be a potential agent for overcoming sorafenib resistance in HCC treatment.

The intrinsic relationship between the atomic structure and macroscopic corrosion behavior has been established, which proposes that the atomic coordination state is another key factor affecting the corrosion resistance and cycling life of hydrogen storage alloys besides elements electronegativity. The density functional theory simulation and experimental results confirm the predictions, shedding light on the design of ultra-long-life hydrogen storage alloys. The as-designed alloy La0.73Ce0.17Y0.1Ni3.75Co1.0Mn0.3Al0.35 exhibits an ultra-long 2415-cycle life, which is almost five times that of the traditional commercial alloy. The usage costs of nickel metal hydride battery based on this alloy is only 1/5 that of Li-ion battery, showing broad market prospect.

In order to compete with Li-ion batteries, the discharge capacity and cycling life of nickel metal hydride batteries need to be further improved. However, this is rather difficult due to poor performances of the negative electrode materials—hydrogen storage alloys. In this work, a new strategy is proposed for designing hydrogen storage alloys with high capacity and long cycling life through theoretical analysis and density functional theory simulation, which points out that it is crucial to substitute Ni atoms inside the alloy with Mg by the precise control of stoichiometric ratio and Mg content. The candidate alloy La0.62Mg0.08Ce0.2Y0.1Ni3.25Co0.75Mn0.2Al0.3 [corresponding to (LaCeYMg) (NiCoMnAl)4.5] exhibits a high capacity of 326.7 mAh g−1 and a capacity retention of 80% after a long cycling life of 928 cycles, showing great potential for applications in nickel metal hydride batteries. The design strategy also provides new insights into the development of new-type high-performance hydrogen storage alloys.

The development of high-power batteries for applications in electric vehicles, power tools, military devices, etc. has attracted great attentions in recent years. Here the synergistic effect between Co3O4 nanocubes and N-doped graphene has been considered to focus on the major obstacle of the sluggish kinetics of carrier transport and electrochemical reaction during charging/discharging. As an example, we have fabricated the Co3O4 nanocubes/N-doped graphene hybrid material and combined it with hydrogen storage alloys. The as-fabricated composite exhibits superior rate performance for applications in nickel metal hydride battery. An ultra-high capacity of 223.1 mAh g−1 is achieved at a specific current of 3000 mA g−1, which is 3.2 times that of the commercial alloy electrode (68.7 mAh g−1). Such remarkable high-rate dischargeability originates from the unique three-dimensional integrated porous structure of Co3O4/N-doped graphene, which provides: (1) small internal resistances due to the conductive substrate of N-doped graphene; (2) high electrocatalytic activity of Co3O4 nanocubes; (3) a suppression of re-stacking of N-doped graphene nanosheets; and (4) efficient ion and electron pathways and also short transport distances.

One demanding challenge in the development of high-power batteries is to achieve superior rate and cycling performances. Here, we report a two-step method to fabricate a hybrid material of surface-amorphized TiO 2 /reduced graphene oxide (SA- TiO 2 /RGO), which exhibits superior electrochemical properties as an anode material in lithium-ion batteries, high rate property of 135.6 mAh g −1 at a current density of 10 A g −1 and cycling stability of 98 mAh g −1 after 2000 cycles at 5 A g −1 . These excellent performances originate from the unique three-dimensional integrated structure of SA-TiO 2 /RGO, which provides: (i) a conductive substrate of RGO; (ii) higher conductivity of SA-TiO 2 relative to crystallized-TiO 2 ; (iii) ultra-small SA-TiO 2 nanoparticles; and (iv) excellent contact between SA-TiO 2 and RGO through C-O-Ti bonds.

Group V elemental few-layered materials with semiconducting electronic properties are emerging as promising 2D layered materials . Since the layered configurations need substrate for device fabrications , their surface energy values could decide their properties. Here, we have performed a systematic density functional theory (DFT) investigation on the surface energies of arsenene and antimonene films as the function of thickness. The results show that the surface energy of β phase increases with increased layered numbers and converges to a constant value at about five layers, while the surface energy of α phase is size-independent. Since the surface energies of both α and β phase are similar, there is the existence possibility of α phase. Those could give references for future manufacture of arsenene and antimonene nano-devices.

The precipitation kinetics during non-isothermal annealing of an Al-Mn alloy (AA3003) rolled over a large strain range (e = 0–2) has been investigated. Precipitation strengthening can overtake recovery softening when prestrained alloy was annealed below 573 K. The precipitate size distributions were similar in undeformed and prestrained alloys annealed at low temperature (673 K). We developed a coupled deformation-recovery-precipitation model for nucleation kinetics of heterogeneous precipitation. Strain-induced dislocations significantly promote nucleation at small and moderate strains while nucleation rate on sub-boundaries of higher misorientation increases by orders of magnitude with strain, and becomes dominant at large strains.

The isolation of different two-dimensional materials and the possibility to combine them in vertical stacks have led to new material systems, namely heterostructures based on two-dimensional crystals. By using density functional theory, we found that the InSe/MoS2 bilayer shows an indirect band gap of 0.65 eV with optical absorption over a wide range (300-800 nm) and a preferable separation of photogenerated electron-hole pairs. Moreover, the band gap can be readily tuned by external strain engineering, leading to a transition from the indirect band gap to a direct band gap of 1.55 eV under 7% compressive strain, where there is an enhanced and continuous spectrum. In addition, under a tensile strain of 9%, the bilayer is metallic. All of these properties enable the development of excellent photoelectric devices from the heterostructures with strain engineering.

Nitrogen fixation under mild conditions has been one of the most important issues and a long-standing challenge in chemistry. By means of density functional theory (DFT) calculations, an experimentally available 2D MoC6 was discovered as a nitrogen reduction reaction (NRR) electrocatalyst. Our results show that MoC6 with high stability can be prepared experimentally. In particular, MoC6 exhibits excellent catalytic activity for N2 fixation at room temperature with a low potential of −0.54 V. The optimal active site, high utilization, selective stabilization of N2H* species and destabilization of the species is responsible for the high activity of MoC6. Our findings provide a rational strategy for nitrogen activation and ammonia production.

The predictions of a new series of two-dimensional (2D) materials, namely, arsenene and antimonene have enriched the field of nano-electronic devices-fabrication. However, the indirect band gap character of the pristine structures slows down the pace of their practical applications. Herein, we prepared and studied novel monolayer AsxSby alloys with excellent stabilities (where x and y denote the atomic ratio of As and Sb elements and x + y = 16). The results indicate that some of the components possess direct band gaps. Moreover, the low effective masses (lower than 0.2m0, where m0 is the static electron mass) of the alloys, which enhanced the device efficiency, were also identified. In particular, α-phase AsxSby (5 ≤ y ≤ 9) harbors effective masses even lower than phosphorene. Our predictions not only inject new vigor into 2D alloys, enriching the candidate materials available in this field, but also highlight the potential of these alloys as fascinating materials for future non-electronic devices.

Cost-effective carbon-based catalysts are promising for electrochemical ammonia synthesis. In the work, the nitrogen reduction reaction (NRR) performances of the single transition metal atom anchored zigzag graphene nanoribbon with H/F termination, termed as TM-G/H and TM-G/F, are systematically investigated via density functional theory calculations wherein V, Fe and Mo are considered among the various TM elements. The N2-to-NH3 conversions are conducted via the distal mechanism under the onset potentials of 0.55 and 0.42 V for Mo-G/H and Mo-G/F, respectively. More interestingly, the edge fluorination suppresses the competing hydrogen reduction reaction in comparison with the hydrogenation counterpart, boosting the NRR efficiency. The electronic analysis elucidates that the edge termination alters the binding strength of Mo anchoring and thereby modifies its affinity toward the NRR intermediates. In this regard, the activity improvement stems from the edge fluorination in combination with the Mo dopant. Beyond element-screening, our finding provides a rational strategy of edge engineering to design carbon-based electrocatalysis.

Clusters with precise numbers of atoms can exhibit unique and unexpected properties due to their size-dependent active sites. Besides, to obtain the superior stability and catalytic activity, an appropriate substrate can prevent the metal clusters aggregating as well as change the geometric and electronic structures of metal clusters. In this study, the catalytic oxidation of CO on the Ag38 cluster supported by graphdiyne (Ag38–GDY) is investigated by density functional theory (DFT) and molecular dynamics (MD) simulations, which provide an intensive understanding of its catalytic properties. Moreover, the process of CO oxidation on the Ag38–GDY system has a high activity with low energy barrier (0.26 eV), which originates from the intrinsic activity of Ag38 cluster and the vital role of GDY.

The poor high-rate dischargeability (HRD) of negative electrode materials (hydrogen storage alloys) has impeded applications of nickel metal hydride batteries in high-power fields, electric vehicles, hydride electric vehicles, power tools, modern military devices, etc. Here we report a facile and effective strategy to enhance the HRD performance of commercial MmNi 3.55 Co 0.75 Mn 0.4 Al 0.3 hydrogen storage alloy (here Mm denotes mischmetals) with high-energy ball milling and addition of graphene nanoplatelets (GNPs). At a discharge current density of 3000 mA g −1 , the capacity retention rate of the alloy electrode could reach 53.0% after ball-milling, and 68.3% after further addition of GNPs, which is 3.2 times that of original alloy electrode (21.5%). Such a superior HRD performance is contributed by (1) smaller particle size of alloys to reduce the diffusion distance of hydrogen atoms; (2) high conductivity of GNPs to accelerate the charge transfer; and (3) interconnected GNPs among alloys to decrease the internal resistance.

To achieve renewable energy technologies, low-cost electrocatalysts for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are required to replace Pt and IrO2/RuO2 catalysts. Based on density functional theory, the catalytic activity of TM3(HHTP)2 (2,3,6,7,10,11-hexahydroxytriphenylene) monolayer and its variations (TMX4, where TM = Fe, Co, Ni, X = O, S, Se) for bifunctional ORR/OER have been investigated. The adsorption ability is dominated by the metal center, in the order of Fe > Co > Ni while the ligand shows the minor contribution. Due to the presence of linear relations between the intermediates, the activity of TMX4 for the ORR/OER follows a dual volcano curve as a function of the OH adsorption strength. Considering the overpotential, CoO4 and CoS4 possess superior bifunctional activity, implying their promise as candidates for the oxygen electrode reaction. This systematical work may open new avenues for the development of high-performance non-PGM catalysts for practical applications of ORR and OER.

The potential of silicene-based integrated electronics originates from its extremely high carrier mobility, whereas the lack of a band gap impedes its application. Thus, opening a sizeable band gap without degrading its carrier mobility is a significant challenge for application in logic circuits. In this study, a sizable band gap is created in silicene by the dual effect of organic molecule adsorption and a substrate. As an electron donor molecule, tetrathiafulvalene (TTF) is found to non-covalently functionalize the silicene sheet. As a result, silicene with adsorbed TTF exhibits an open band gap. When silicane (hydrogenated silicene) substrate is applied, the band gap further widens. Moreover, the high carrier mobility is largely retained. These results provide effective and reversible routes for engineering the band gap of silicene.

Arsenene-based device applications such as transistors and photodetectors benefit from precise control over the carrier type and concentration as well as a combination of both high-quality p-doped and n-doped components to form p–n junctions. Here, it is demonstrated using first-principles calculations that selective organic molecular adsorption allows us to effectively control the carrier type in arsenene. Moreover, upon applying an in-plane tensile strain, the carrier concentration effectively increases. Furthermore, the BN substrate can increase the structural stability without any impact on the doping character of the arsenene sheet. This opens the possibility of creating arsenene p–n junctions.

Three series of poly(ether sulfone)s are synthesized from POSS via nucleophilic aromatic substitution polycondensation with different fluoride bisphenols. The structures of the PESs are characterized by IR, NMR and WAXD spectroscopy. The incorporation of POSS and trifluoromethyl into a poly(ether sulfone) matrix at various molar percentages of POSS result in a dramatic decrease in dielectric constant, dielectric loss as well as a significant increase in hydrophobicity of the system. The lowest dielectric constant 2.23 (1 MHz) is obtained at 40% DDSQ–6FPH–PES (molar percent content of DDSQ = 40%). The highest water contact angle 104° is obtained at 20% DDSQ–6AF–PES. Dielectric loss of most synthetic polymers is lower than 0.002. The number of trifluoromethyl groups and the attached position of these to the polymer chain also play essential roles in the dielectric properties, hydrophobicity and thermal properties. The results are discussed and interpreted in detail.

Development of the efficient bifunctional oxygen electrode is indispensable but challenging for the rechargeable metal–air batteries. The oxygen reduction reaction and oxygen evolution reaction of theTMN4 embedded graphene, graphane and fluorographene are systematically investigated by the density functional theory calculations (TM = Fe, Co and Ni). Our results show that the ORR/OER activity and the stability of the TMN4 moieties are dramatically changed by the graphene functionalization. According to the free energy analysis, the H/F decoration on the carbon skeleton improves the activities of FeN4 and CoN4 moieties, in comparison with the graphene counterpart. In detail, the FeN4-based electrodes are potential ORR ones where the overpotentials are reduced from 0.98 V of G/FeN4 to 0.46 V of GH/FeN4 and 0.38 V of GF/FeN4. Meanwhile, the CoN4-based electrodes possess good OER efficiency featured with the overpotentials of −0.50 V and −0.53 V for GH/CoN4 and GF/CoN4 with respect to −0.72 V for G/CoN4, respectively. On the other side, the high thermodynamic barrier of NiN4-based electrodes limits its application, regardless of the supports. Furthermore, the binding strengths between TM and its N coordination are substantially increased due to the presence of H/F attachments, indicating the enhanced TM capture, which ascribes to the corresponding wrinkle sp3 structure. Additionally, the structural integrity without any degradation in the molecular dynamic stimulation further supports the thermodynamic stability at the room temperature. The robustness of GH/TMN4 and GF/TMN4 illustrates the feasibility of the experimental synthesis. Considering the possible dehydrogenation of the graphane at the elevated temperature, the fluorographene with atomically dispersed FeN4 and CoN4 moieties is recommended as promising oxygen electrode. To shed light on the physical origination, the electronic structure analysis correlates the activity enhancement with the change of the TM d-orbital, being evidenced by the linearity between the OH affinity and the d band center. Therein, the influences of the graphene functionalization on the electrocatalysis provide new insights into the design of the bifunctional oxygen electrode.

The poor high-rate dischargeability of negative electrode materials (hydrogen storage alloys) has hindered applications of nickel metal hydride batteries in high-power fields, new-energy vehicles, power tools, military devices, etc. In this work, a new strategy is developed to improve the high-rate performance of hydrogen storage alloys by coating MoS 2 nanosheets on alloy surfaces. The capacity retention rate of the composite electrode reaches 50.5% at a discharge current density of 3000 mA g −1 , which is 2.7 times that of bare alloy (18.4%). The density functional theory simulations indicate that such an outstanding performance is derived from adjustments of ion concentrations at the electrode/electrolyte interface by MoS 2 nanosheets: (1) the higher OH − concentration facilitates the electrochemical reaction of MH ads + OH − − e − → M + H 2 O; and (2) the lower H + concentration leads to a large gradient between the electrode/electrolyte interface and interior of alloys, which is beneficial for the diffusion of atomic hydrogen during the discharging process.

In order to investigate the effect of polyhedral oligomeric silsesquioxane content and the structure-function related on the dielectric property and hydrophobicity, three kinds of poly(aryl ether sulfone)s (PAESs) random terpolymer with different chemistry structure at variable polyhedral oligomeric silsesquioxane content in the main chain are prepared. The structures of PAESs are characterized by infrared (IR), nuclear magnetic resonance (NMR), and wide-angle X-ray diffraction (WXRD) spectra. The results show that the dielectric constant initially increases then decrease to 2.68 at 100%-double-decker silsesquioxane (DDSQ)-PAES(molar content of DDSQ = 100%) at 1 MHz. The contact angle increased to 97.5° at 100%-DDSQ-PAES. While the chemical structure of organic chains also plays an important role on thermostability, dielectric, and hydrophobic properties. The results are discussed and interpreted in detail. Copyright © 2016 John Wiley & Sons, Ltd.

The main challenge of applications of nickel metal hydride batteries in high power fields, new-energy vehicles, power tools, military devices, etc., originates from poor high-rate dischargeability of their negative electrode material—hydrogen storage alloys (HSAs). Here we report the design and synthesis of a composite by coating HSAs with reduced graphite oxide (RGO) via a top-down route. The capacity retention rate of the fabricated HSAs/RGO hybrid electrode reaches 51.25% at a discharge current density of 3000 mA g −1 , which is almost 4 times that of bare HSAs electrode (13.51%). Such an enhanced high-rate dischargeability performance is caused by (1) high specific surface area of RGO to increase active sites; (2) high conductivity of RGO to accelerate the charge transfer rate; and (3) unique interconnected RGO sheets among HSAs to reduce the internal resistance.

Nano-SiC particulates (n-SiCp) reinforced 2014Al matrix composites with different reinforcement volume fractions (0, 0.25, 0.5 and 1 vol.-%) were fabricated by powder metallurgy combined with hot extrusion. The effect of volume fraction of n-SiCp on mechanical properties of composites was studied at both ambient and elevated temperatures. The increase of n-SiCp content led to an increase in yield strength (YS) and ultimate tensile strength (UTS) and a slight decrease in elongation which is much better than the composites reinforced with micro-SiCp. The 0.5 vol.-% n-SiCp/2014Al composite observed the highest YS and UTS of ∼378 and ∼573 MPa at room temperature and of ∼303 and ∼409 MPa at 473 K. The enhancement of the properties is suggested to be induced by uniformly dispersed and well-bonded n-SiCp reinforcements as well as the age-hardening effect of the more and finer precipitates.

Using first-principles DFT calculations, the pathway and the energy barrier of phase transition between 2H and 1T' have been investigated for MoTe2 and WTe2 monolayers. The Phase transition is controlled by the simultaneous movement of metal atoms and Te atoms in their plane without the intermediate phase 1T. The energy barrier (less than 0.9 eV per formula cell) is not so high that the phase transition is dynamically possible. The relative stability of both 2H and 1T' phases and the energy barrier for phase transition can be modulated by the biaxial and uniaxial strain. The dynamic energy barrier is decreased by applying the strain. The phase transition between 2H and 1T' controlled by the strain can be used to modulate the electronic properties of MoTe2 and WTe2.

Two-dimensional crystals with weak layer interactions, such as twisted graphene, have been a focus of research recently. As a representative example, transitional metal dichalcogenides show a lot of fascinating properties due to stacking orders and spin-orbit coupling. We analyzed the dynamic energy barrier of possible phase transitions in MoX2 (X = S, Se and Te) with first-principles methods. In the structural transition from 2Hc to 2Ha, the energy barrier is found to be increased following an increase of pressure which is different from the phase transition in usual semiconductors. Among MoS2, MoSe2 and MoTe2, the energy barrier of MoS2 is the lowest and the stability of both 2Hc and 2Ha is reversed under pressure for MoS2. It is found that the absence of a phase transition in MoSe2 and MoTe2 is due to the competition between van der Waals interaction of layers and the coulomb interaction of Mo and X in nearest-neighbor layer of Mo in both phases.

Pt1ML/Pd3Al, which comprises a Pd3Al core protected by a Pt monolayer, may experience Al dealloying because of the strong affinity of Al toward O. To circumvent this issue, the Pt2ML/Os/Pd3Al catalyst has been designed to suppress the migration of Al by inserting an Os monolayer at the interface between the Pd3Al core and two Pt monolayers. On the basis of segregation energies, Al leaching from the core to the 1st layer is determined to be endothermic even under O coverage, indicating an energetic preference for Al to reside in the core structure. The Pt2ML/Os/Pd3Al catalyst benefits from the energetic disadvantage of the inward movement of Os and the presence of the 2 ML Pt layer. As an ORR electrocatalyst, the relatively weak adsorption ability of Pt2ML/Os/Pd3Al suggests improved ORR activity. Finally, a representative OOH association mechanism with low reaction barriers of 0.46, 0.31, 0.38 and 0.41 eV for the OOH formation, OOH dissociation, OH formation and H2O formation steps suggests that the catalyst can effectively activate the O–O bond and eliminate OH, which can act as a catalytic poison. These findings suggest the design of stable sandwich catalysts as potential candidates for ORR electrocatalysis.

Forty-five KPC-producing Enterobacteriaceae strains were isolated from multiple departments in a Chinese public hospital from 2014 to 2015. Genome sequencing of four representative strains, namely Proteus mirabilis GN2, Serratia marcescens GN26, Morganella morganii GN28, and Klebsiella aerogenes E20, indicated the presence of blaKPC-2-carrying IncX6 plasmids pGN2-KPC, pGN26-KPC, pGN28-KPC, and pE20-KPC in the four strains, respectively. These plasmids were genetically closely related to one another and to the only previously sequenced IncX6 plasmid, pKPC3_SZ. Each of the plasmids carried a single accessory module containing the blaKPC-2/3-carrying ΔTn6296 derivatives. The ΔTn6292 element from pGN26-KPC also contained qnrS, which was absent from all other plasmids. Overall, pKPC3_SZ-like blaKPC-carrying IncX6 plasmids were detected by PCR in 44.4% of the KPC-producing isolates, which included K. aerogenes, P. mirabilis, S. marcescens, M. morganii, Escherichia coli, and Klebsiella pneumoniae, and were obtained from six different departments of the hospital. Data presented herein provided insights into the genomic diversity and evolution of IncX6 plasmids, as well as the dissemination and epidemiology of blaKPC-carrying IncX6 plasmids among Enterobacteriaceae in a hospital setting.

The bulk as cast Zr50Cu50 − xAlx alloys with various microstructural phase constituents were prepared by copper mould casting. It is found that the mechanical properties and workhardening behaviours of Zr50Cu50 − xAlx alloys strongly depend on the microstructural phase constituents. The Zr50Cu44Al6 glassy composites constituted by ZrCu(B2) austenite and ZrCu martensite are able to achieve high strength and large plastic deformation together with pronounced workhardening. The ZrCu martensitic alloys show plastic deformation and workhardening. The Zr50Cu47Al3 diphase alloy constituted by ZrCu (B2) austenite and ZrCu martensite provides ultrahigh workhardening ability (Hc = 3.21) as expected for a deformation induced martensitic transformation. For the alloy containing ZrCu (B2) austenite phase, the deformation induced martensitic transformation is believed to cause a strong workhardening and contribute to a large compression deformability.

A series of novel copoly(aryl ether sulfone)s with polydimethyl (PDMS) and double-decker-shaped silsesquioxane (DDSQ) in the main chain were synthesized by nucleophilic substitution polymerization approach. Dihydroxy terminated eugenosiloxanes (2OH-PDMS-n) and 3,13-di(2-methoxy-4-propylphenol)octaphenyl DDSQ (2OH-DDSQ) were synthesized. These two difunctional oligomers were used to copolymerize with 4-fluorophenyl sulfone to obtain poly(aryl ether sulfone) containing cage and linear organosiloxane (Si-PES) through one-step high-temperature solution method. Si-PES with multiple PDMS and DDSQ contents in the main chains were obtained by adjusting the molecular weight of 2OH-PDMS-n and controlling the molar ratio of 2OH-DDSQ to 2OH-PDMS-n. The dielectric constants sharply decreased as organosiloxane was introduced compared with traditional PES which the lowest value was achieved at 5% DDSQSi–PES (2.36 at 1 MHz). In addition, enhanced hydrophobic capacity peaks were obtained at 50% DDSQSi-PES surface hydrophobicity (113°) as the synergies of both linear organosiloxane and DDSQ. Furthermore, thermal and crystallization behaviors, as well as surface properties, were investigated.

A series of novel structural phosphorus-containing polyimide–polyhedral oligomeric silsesquioxane (POSS) nanocomposites with varying phosphorus contents were synthesized. The nanocomposites displayed outstanding thermal properties. The glass transition temperature was increased to 294.87 °C when the phosphorus content was 1.61 wt% and the anti-degradation properties were also obviously enhanced. Moreover, the nanocomposites presented much higher atomic oxygen (AO) durability compared with pure polyimide because of the incorporation of special functional groups of phosphorus oxide and POSS. The AO erosion yields decreased to 51.9% of pure polyimide–POSS nanocomposites when the phosphorus content was increased to 1.61 wt%. Furthermore, the mechanism of phosphorus and POSS synergistic AO resistance was explored via XPS and SEM. Three kinds of silicon particles with different binding energies and two kinds of phosphorus elements with different binding energies were formed because of AO exposure and the phosphorus and POSS synergy. Highly effective self-passivating layers were formed to protect the underlying material from AO attack.

Although Au–Cu alloy nanoparticles on inert substrates show high activity for catalyzing CO oxidation, the corresponding catalytic mechanism is not clear. To clarify the mechanism of this alloy catalysis method, CO oxidation reactions on Au–Cu alloy surfaces with different surface oxidation states are studied via density functional theory simulations. The simulation results indicate that on AuCu(111) and Cu2O/Au3Cu(111), CO and O2 cannot move together for reactions since they are adsorbed on separate Cu sites. On Cu2O–Au/Au3Cu(111), O2 prefers to be located at the Cu hollow sites near Cu2O–Au interfaces. When CO diffuses to its neighboring Au sites, they can easily combine to generate CO2, for which the reaction barriers are no more than 0.42 eV. The Au and Cu synergetic effect for catalyzing CO oxidation can be realized on Cu2O–Au interfaces at Au–Cu nanoparticle surfaces.

This work focuses on the design of unique “cage–cage” shaped low dielectric constant and hydrophobic materials with nano-sized pores and few polarizable groups. Therefore, a novel double-decker structural fluorinated POSS was first synthesized, which then reacted with a diphenol POSS to produce linear hybrid polymers. When the merits of fluoride and nanoporous structures are combined, the dielectric constant of the hybrid material decreases significantly (2.24 at 1 MHz) and a low surface energy (contact angle of 107° in water) of the material, as well as good solubility and thermal properties are obtained.

Background Primary insomnia is one of the most common issues for adults. However, whether to use music intervention as a non-pharmacological method of treatment, as well as which treatment should be preferred, is still a matter of controversy. Therefore, we aimed to compare and rank music interventions and no-music controls for primary insomnia patients. Methods A network meta-analysis was used to identify evidence from relevant clinical trials. We searched PubMed, Embase, the Cochrane Library, and the China National Knowledge Infrastructure Library for publications up to May 2017, pertaining to music intervention for primary insomnia patients. The prespecified primary outcome was sleep quality (scored by the PSQI and overall), and the secondary outcomes were sleep onset latency and sleep efficiency. We did pairwise meta-analyses using the random-effects model, later completing the random-effects network meta-analyses. The study was registered with PROSPERO, number CRD42017064750. Results We deemed 20 trials to be eligible, involving 1339 patients and 12 intervention arms. For PSQI scores, all intervention arms were statistically more effective than the usual care, with patients ranking listening to music as the best means of intervention (SMD: −0.61, 95%CrI: −1.01 to −0.20). For overall sleep quality, only music-associated relaxation was statistically more effective than the patients' usual care (−0.28, −0.48 to −0.08). In terms of sleep onset latency, music-associated relaxation and listening to music had significant advantages (−0.26, −0.64 to −0.09, and −0.28, −0.53 to −0.02); listening to music and music with exercise displayed a tendency to improve sleep efficiency. Conclusions When considering the efficacy, music intervention seemed to offer clear advantages for adults with primary insomnia. Listening to music and music-associated relaxation are probably the best options to consider in the application of music intervention.

In this work, based on experimental possibilities, our first-principles calculations predict a sizeable bandgap opening in bilayer graphene (BLG) by n-doping from decamethylcobaltocene (DMC) and p-doping from functionalized amorphous SiO 2 ( a -SiO 2 ) gate dielectric. With DMC monolayer on BLG and the maximum O 2 − on the surface of a -SiO 2 gate dielectric, the dual-doped BLG presents a bandgap of 390–394 meV and a Dirac level shift of −59 to −52 meV. The former is very close to the technical requirement of 400 meV, while the latter properly lies in the accessible range of the gate voltage of 300 meV. The high carrier mobility largely remains with the on/off current ratio satisfying the technical requirement of 10 4 −10 7 . The external electric field is not needed in this technique, which avoids a complex fabrication step for preparing a dual-gate structure and a substantial reduction in carrier mobility and on/off current ratio induced by adding an extra gate.

Core–shell nested structure of amorphous carbon coated on crystalline ZnO (carbonized ZnO) was synthesized by sol–gel method as precursor. Disordered ZnO nanoparticles were successfully prepared by annealing the carbonized the ZnO precursor. HRTEM, Raman and XPS analyses showed that the ZnO nanoparticles contain high concentration of oxygen-deficiency defects which enable them exhibiting an abnormal intense deep-level emission centered at green luminescence and spreading over a wide wave length range of 420–660 nm and having a negligible UV emission in its photo luminescence (PL) spectrum. They also show an enhanced photocatalytic activity in degradation of methylene blue (MB). Experiments and theoretical simulation based on density functional theory showed that the intense deep-level emission and improved photocatalytic ability should attributed to their abundant oxygen-deficiency defects in the ZnO nanoparticles introduced by the two-step preparation method.

Cu/N-codoped TiO 2 nanoparticles were prepared by sol–gel technique. Their structure, surface chemical composition, and optical absorption were characterized. All as-prepared samples consisted of the anatase phase. It was found that Cu atoms replaced Ti atom sites, and N atoms occupied the O atom sites and interstitial sites in the TiO 2 lattice. The optical absorption results reveal that Cu/N codoping could greatly enhance the absorption of TiO 2 in the entire visible region, leading to a decrease in the band-gap energy of TiO 2 . It also significantly enhanced the solar-driven catalytic activity of TiO 2 in the degradation of methylene blue in solution. The sample 2.0 at% Cu/N-codoped TiO 2 displayed the highest solar-driven catalytic efficiency among all tested samples.

Relying on our size-dependent cohesive energy and lattice constant functions, we established the Morse function in a unified form for nanoscaled cubic metals, involving metallic nanoparticles (NPs) and nanostructured materials (NSs). At the equilibrium position at 0 K, the depth of the potential well becomes shallow with smaller D especially for NPs, where D denotes the diameter of NPs or the grain size of NSs. This gives rise to the contraction or expansion of the interatomic spacing for NPs or NSs, respectively. The asymmetry of the binding energy curve in NPs is stronger than in NSs. The difference between NPs and NSs is largely associated with the distinction in the coordination imperfection between the surface and the grain boundary. The established function was supported by available experimental and computer simulation results for NPs and NSs.

Nanosized Cu-doped TiO 2 film was prepared by the sol–gel spin coating technique. XPS analysis showed that Cu atoms had been successfully doped into TiO 2 lattice, which hence modified the surface chemical composition. As a result, the Cu-doped TiO 2 thin film possessed a superhydrophilic surface with a water contact angle (WCA) only 5.1° and exhibited excellent anti-fogging behavior. The Cu-doped TiO 2 thin film also exhibited a much better photocatalytic activity than the reference TiO 2 thin film, as evaluated by the degradation of 10 mg/L methylene blue (MB) solution under simulated solar-driven irradiation.

Single atom catalysts (SAC) are highly desirable to maximize atom efficiency, while fabricating them is largely dependent on choosing a suitable substrate to effectually fasten them. Here, in terms of strong metal–metal interaction, first-principle calculations have been performed to study the possibility of monolayer polymeric transition metal–phthalocyanines (TM–Pcs, M from Sc to Zn) as the substrate in an effect to obtain evenly distributed single Pt atom catalyst. We found that Ti–Pc is the most appropriate compound by virtue of high binding strength of Pt/Ti–Pc system and high diffusion energy barrier of Pt catalyst atom, which jointly prevent the formation of Pt clusters. CO oxidation on Pt/Ti–Pc presents some unexpected behaviors, where a presorbed CO (pCO) molecule could activate the catalyst and reduce the reaction barrier. Examining the electronic structure evolution in the reaction process demonstrates that the presence of a pCO promotes O2 adsorption and activation. Our results demonstrate tha...

The geometric and electronic properties of silicene paired with a MoS2 substrate are studied systematically by using density functional theory with van der Waals corrections. It is found that the nearly linear band dispersions can be preserved in the heterobilayers due to the weak interface interactions. Meanwhile, the band gap is opened because of the sublattice symmetry broken by the intrinsic interface dipole. Moreover, the band gap values could be effectively modulated under an external electric field. Therefore, a way is paved for silicene-MoS2 heterobilayers to be candidate materials for logic circuits and photonic devices.

The dense TiC-TiB2/Ni composite was successfully fabricated through the pressure-assisted thermal explosion reaction from Ti, B4C and Ni powder blends in air. The ignition temperature (625 degrees C) in air was 415 degrees C lower than that in vacuum. The decreased ignition temperature resulted from a chemical oven mechanism in which the oxidation and nitrification of Ti and the oxidation of B4C released the heat and promoted the occurrence of the thermal explosion reaction. The composites prepared in air and vacuum had similar phase constituents and microstructure. Moreover, the composite prepared in air possessed comparable hardness, flexural strength and fracture toughness to the composite prepared in vacuum.

Using density-functional theory, we show that the NiAs-type is a more favorable structure for the (W0.5Al0.5)C phase than the experimentally proposed WC-type structure when we compare the thermodynamic, dynamic and elastic properties of the two types. Furthermore, it is found that this NiAs-type (W0.5Al0.5)C phase could be synthesized under pressures of 12 GPa or higher, while the advanced mechanical properties of the (W0.5Al0.5)C phase, including the bulk modulus of B = 268 GPa, the shear modulus of G = 206 GPa, and the hardness of HV = 30 GPa, could be reproduced by the NiAs-type structure. The fantastic mechanical properties of the phase are attributed to the synergistic effect of stronger C–Al bonding and weaker C–W bonding of the NiAs-type structure.

The cold rolling strain effect on the tensile properties of a high nitrogen alloyed austenitic steel was systemically investigated. Quasi-static tensile experiments were performed on the samples with different cold rolling strain. The material possessed good balance between strength and ductility in the entire rolling strain range. Mechanical property and microstructure of the nitrogen alloyed austenitic steel were greatly affected by cold rolling strain. With the increase in cold rolling strain, the strength increased sharply but the ductility declined. That is related to the gradual changes of microstructure induced by the cold rolling process. The cold rolling process leads to substantial microstructural change, from the appearance of slip bands and twins at low cold rolling strain; the microtwins formation at intermediate cold rolling strain and followed by sequences of their bending, breaking and disappearance; and finally to the formation of drossy twins at the high cold rolling strain.

In order to search for a gas sensor to detect hydrogen fluoride (HF), the adsorption of HF on transition metal-embedded graphene (TM/graphene) is investigated by density functional theory calculations. Compared with the relatively weak adsorption on other TM/graphene systems, HF molecule tends to be adsorbed on Ti/graphene with appreciable adsorption energy. Based on these calculations, two gas sensing mechanisms are proposed and revealed that both surface reconstruction and charge transfer result in a change of electronic conductance of Ti/graphene. Thus, this developed Ti/graphene would be an excellent candidate for sensing HF with lower cost and higher activity.