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In the present research, nutrient broth (NB) medium was identified to be able to neutralize the antibacterial activity of chitosan and its derivatives. Therefore, an improved test method independent of NB medium was proposed to precisely quantify the antibacterial effectiveness and efficiency of chitosan. The minimum bactericidal concentration (MBC) of chitosan was 60 μg mL−1 against S. aureus and E. coli, and 0.01 % (w/v) chitosan could kill 100 % of bacteria within 3 min. From another point of view, the neutralizing efficiency of NB could be tripled by adding 25 g L−1 of sodium chloride. Then the neutralizing mechanism of NB medium was ascribed to flocculation between chitosan and protein. Adding extra sodium chloride could significantly reduce the size of floccules, and smaller floccules would lose the ability of binding with bacteria directly, showing higher neutralizing rate on the macro scale.

A highly active and cheap catalyst is also key to hydrogen production by water splitting. However, most of the high-efficiency catalysts reported to date only are catalytically active for either the hydrogen evolution reaction (HER) or the oxygen evolution reaction (OER), which makes the development of multifunctional catalysts more meaningful. Here, for the first time, Co(CO3 )0.5 OH. 0.11 H2 O (CHCH) as precursor with different microstructures on the surface of nickel foam (NF) was obtained using a facile hydrothermal method. The CoP/NF catalyst was obtained after thermal phosphating that retained the microhierarchical structure of the precursor and greatly improved the catalytic performance, with a highly efficiency performance as HER and OER dual-functional catalyst. Density functional theory (DFT) calculations showed that the possible reason for the excellent performance of the CoP/NF layered structure is an increase in the number of of surface defects and an increased active surface area. The results reported in this paper show that CoP/NF, a layered bifunctional electrocatalyst, is a cost-effective and efficient water-splitting electrode. This finding can offer the opportunity for the commercial use of excess electric energy for large-scale water splitting hydrogen production.

During the past years, much research work has been focused on efficiently harvesting solar energy with black silicon (b-Si). However, semiconductor Si can only utilize solar energy with wavelength smaller than λ = 1110 nm (bandgap Eg = 1.12 eV) for photovoltaic applications or photoelectrochemical conversions. Light with wavelength beyond the band edge (above λ = 1110 nm) cannot be used. Here, we prepared highly conductive b-Si without an apparent optical bandgap by a reactive ion etching process, which can largely absorb light with a wide range wavelength and even far into the near-infrared region (∼2500 nm). The optimized b-Si with surface texture shows the specular reflection rate lower than 0.1% and the average total reflection (specular reflectance + diffuse reflectance) is about 1.1%. Additionally, we briefly introduce the mechanism and reflection principle of surface nanostructured b-Si. By using b-Si structured material, we successfully convert the solar energy to electric power via photo-thermoelectric conversion, especially solar energy exceeding 1110 nm wavelength can also be efficiently used. The excellent light trapping of sunlight shows great potential for photothermal applications, such as photothermal imaging, seawater desalination, and further applications.

2,5-Furandicarboxylic acid (FDCA), as an important monomer to produce biodegradable polymers, is a hot compound in the field of electrocatalysis. Designing high-activity and low-cost electrocatalysts for the production of high concentration FDCA is an urgent and challenging task. Here, a cactus-like NiCoP nanoplate was prepared as a robust electrocatalyst to enable 5-hydroxymethylfurfural (HMF) oxidation to FDCA at high concentration. In situ Raman spectroelectrochemical analysis investigated the dynamic structural evolution of the NiCoP surface during the electrooxidation of HMF. The substituted Co atoms make the NiOOH active species easier to form on the NiCoP surface than Ni2P at low constant voltage, which promotes the oxidation of HMF into FDCA. The total potential of coupling the cathodic H2 reduction reaction with the anodic HMF oxidation reaction (HMFOR) is only 1.464 V when NiCoP is the electrode material. The design of the flow-through mode reactor optimized the mass transfer process in the reaction, and further improved the coupling efficiency. The conversion rate of HMF and yield of FDCA reach 98.7% and 98.8%, respectively, even when the concentration of HMF is as high as 300 mM.

Rational optimization of the surface electronic states and physical structures of non-noble metal nanomaterials is essential to improve their electrocatalytic performance. Herein, we report a facile dual-regulation strategy to fabricate NiFeP/Ni (P-NiFeP/Ni) porous nanoflowers, which involves Fe-doping and creating pores on nanosheets. The as-prepared P-NiFeP/Ni has a hierarchically porous surface, which exposes more electrochemically active sites and dramatically enhances the electron transfer rate. Thus, it exhibits excellent catalytic activity in both anodic hydrazine oxidation reaction (HzOR) and cathodic hydrogen evolution reaction (HER). Interestingly, the coupled electrolysis cell only offers a potential of 0.162 V at 10 mA cm−2 to enable HzOR boosted H2 evolution, highlighting an energy-saving hydrogen evolution strategy.

Efficient and green exfoliation of bulk MoS2 into few-layered nanosheets in the semiconducting hexagonal phase (2H-phase) remains a great challenge. Here, we developed a new method, water-assisted exfoliation (WAE), for the scalable synthesis of carboxylated chitosan (CC)/2H-MoS2 nanocomposites. With facile hand grinding of the CC powder, bulk MoS2 and water followed by conventional liquid-phase exfoliation in water, this method can not only efficiently exfoliate the 2H-MoS2 nanosheets, but also produce two-dimensional (2D) CC/2H-MoS2 nanocomposites. Interestingly, the intercalated CC in MoS2 nanosheets increases the interlayer spacing of 2H-MoS2 to serve as good candidates for the semiconductor devices. 2D CC/2H-MoS2 nanocomposites show superior electronic rectification effects in nonvolatile write-once-read-many-times memory (WORM) behavior with an ON/OFF ratio over 103, which can be rationally controlled by the weight ratios of CC and MoS2. These findings by the WAE method would open tremendous potential opportunities to prepare commercially available semiconducting 2D nanocomposites for promising high-performance device applications.

A high-temperature proton exchange membrane was fabricated based on polyvinylidene fluoride (PVDF) and polyvinylpyrrolidone (PVP) blend polymer nanofibers. Using electrospinning method, abundant small ionic clusters can be formed and agglomerated on membrane surface, which would facilitate the proton conductivity. To further enhance the conductivity, phosphoric acid (PA) retention as well as mechanical strength, sulfamic acid (SA)-doped metal–organic framework MIL-101 was incorporated into PVP-PVDF blend nanofiber membranes. As a result, the anhydrous proton conductivity of the composite SA/MIL101@PVP-PVDF membrane reached 0.237 S cm−1 at 160 °C at a moderate acid doping level (ADL) of 12.7. The construction of long-range conducting network by electrospinning method combined with hot-pressing and the synergistic effect between PVP-PVDF, SA/MIL-101 and PA all contribute to the proton conducting behaviors of this composite membrane.

It is a challenge to rationally design an organic molecule with thermally activated delayed fluorescence (TADF) due to the intrinsically spin-forbidden transition. Meanwhile, those reported TADF organic molecules have difficulty to be directly applied in the field of biological and medical imaging because they usually have no water solubility. Here, a water-soluble TADF organic molecule DCF-BXJ was developed by introducing a flexible propenyl group into the commercial traditional fluorophore DCF (2,7-dichlorofluorescein). The flexible group provides nonradiative rotational motion, which causes an efficient energy level cross between the S1 state and the T2 state of DCF-BXJ. Results of transient absorption spectra and theoretical calculations supported that nonradiative rotational motion of the flexible group can enhance intersystem crossing (ISC) and bring out TADF. This work provides a new mechanism explanation for TADF existing in organic molecules.

Low-cost, non-noble-metal electrocatalysts are required for direct methanol fuel cells, but their development has been hindered by limited activity, high onset potential, low conductivity, and poor durability. A surface electronic structure tuning strategy is presented, which involves doping of a foreign oxophilic post-transition metal onto transition metal aerogels to achieve a non-noble-metal aerogel Ni97 Bi3 with unprecedented electrocatalytic activity and durability in methanol oxidation. Trace amounts of Bi are atomically dispersed on the surface of the Ni97 Bi3 aerogel, which leads to an optimum shift of the d-band center of Ni, large compressive strain of Bi, and greatly increased conductivity of the aerogel. The electrocatalyst is endowed with abundant active sites, efficient electron and mass transfer, resistance to CO poisoning, and outstanding performance in methanol oxidation. This work sheds light on the design of high-performance non-noble-metal electrocatalysts.

Organic ultralong room-temperature phosphorescence (OURTP) has boomed recent advances of organic optoelectronics with the significant breakthrough in facilitating the intersystem crossing and stabi...

To improve densification degree and reduce process time, microwave sintering and heat molding method were combined to prepared SiC matrix reinforced SiC (SiC/SiC) composite via polymer infiltration and pyrolysis process (PIP). The effects of heat molding pressures on the densification process, flexural behaviors and failure modes of the fabricated SiC/SiC were examined via scanning electron microscopy (SEM), computed tomography (CT) technique and mercury intrusion test. Results indicate that heat molding process promoted the densification degrees of SiC/SiC and adjusted the interphase bonding between SiC matrix and SiC fibers on the basis of rapid microwave heating. Owing to the appropriate interphase bonding, SiC/SiC composites fabricated under the heat molding pressure of 3 MPa had preferable flexural properties and failure mode.

The MAX phase Ti3SiC2 has broad application prospects in the field of rail transit, nuclear protective materials and electrode materials due to its excellent electrical conductivity, self-lubricating properties and wear resistance. Cu-Ti3SiC2 co-continuous composites have superior performance due to the continuous distribution of 3D network structures. In this paper, the Cu/Ti3SiC2(TiC/SiC) co-continuous composites are formed via vacuum infiltration process from Cu and Ti3SiC2 porous ceramics. The co-continuous composites have significantly improved the flexural strength and conductivity of Ti3SiC2 due to the addition of Cu, with the conductivity up to 5.73×105 S/m, twice as high as the Ti3SiC2 porous ceramics and five times higher than graphite. The reaction between ingredients leads to an increase in the friction coefficient, while the hard reaction products (TiCx, SiC) lower the overall wear rate (1×10−3 mm3/(N•m)). Excellent electrical conductivity and wear resistance make co-continuous composites more advantageous in areas such as rail transit.

The loading modes and roof lithology have a significant influence on the mechanical properties of coal seams. To reveal the failure modes and energy evolution law of underground coal during the mining process, conventional uniaxial and uniaxial cyclic loading tests were carried out on three types of samples: coal, rock, and coal-rock combinations. The results show that the samples mainly behave with three failure modes (shear slip, tensile splitting, and fracture), and all the coal sections in the coal-rock combinations fail, whereas most rock sections remain intact. The compressive strength of the coal-rock combination is higher than coal and much smaller than rock. Compared with the conventional uniaxial loading condition, both the maximum deformation before failure and Young’s modulus under the cyclic loading condition are greater, and the latter increases quadratically with the cycle index. The energy densities are also calculated, and their variations are analysed in detail. The results show that with increasing cycle index, both the elastic energy stored in the sample and the dissipated energy increase in a quadratic function, and the failure process becomes more intense. This research reveals the failure modes, deformation characteristics, and energy evolution of the coal-rock combination under different loading conditions, which can provide strong support for controlling underground surrounding rocks of the coal face and roadway in coalmines.

The interfacial activity of fullerene surfactants at the air-water interface is studied via molecular dynamics and metadynamics simulations. Fullerene surfactants with different charges show different surface activity. Meanwhile, studies show that fullerene surfactants with zero or one positive charge show interesting interface behaviour, i.e. the hydrophobic fullerene of the fullerene surfactant with zero charge orients to bulk water while the fullerene surfactant with one positive charge can be a hydrophilic and hydrophobic rotator at the air-water interface.

Introducing multiphase structures into benzoxazine (BOZ)/epoxy resins (ER) blends via reaction-induced phase separation has proved to be promising strategy for improving their toughness. However, due to the limited contrast between two phases, little information is known about the phase morphological evolutions, a fundamental but vital issue to rational design and preparation of blends with different phase morphologies in a controllable manner. Here we addressed this problem by amplifying the difference of polymerization activity (PA) between BOZ and ER by synthesizing a low reactive phenol-3,3-diethyl-4,4′-diaminodiphenyl methane based benzoxazine (MOEA-BOZ) monomer. Results indicated that the PA of ER was higher than that of BOZ. The use of less reactive MOEA-BOZs significantly enlarged their PA difference with ER, and thus increased the extent of phase separation and improved the phase contrast. Phase morphologies varied with the content of ER. As for the phase morphological evolution, a rapid phase separation could occur in the initial homogeneous blends with the polymerization of ER, and the phase morphology gradually evolved with the increase in ER conversion until the ER was used up. The polymerization of ER is not only the driving-force for the phase separation, but also the main factor influencing the phase morphologies.

Three-dimensional four-directional (3D4d) braided SiCf/SiC composites were prepared by combination methods of polymer impregnation and pyrolysis (PIP) and electrophoretic deposition (EPD). Differences in the mechanical properties between the composites manufactured at different pyrolysis temperatures were investigated. Mechanical properties decreased significantly as the sintering temperature increased, mainly due to the degradation in the mechanical properties of the KD-Ⅱ fibers and the increasing defects. Thermal conductivities of the composites were characterized as well. The results indicated that, due to a higher degree of crystallization of the matrix derived from the precursor, thermal conductivities of the composites greatly increased with the increasing pyrolysis temperature. Especially when the pyrolysis temperature was 1800 °C, the thermal conductivity reached a relatively high value of 43.15 W/(m·K) at room temperature.

SiCf/SiC composites using KD-I and KD-II SiC fibers braided preforms as the reinforcements were fabricated by applying the polymer impregnation and pyrolysis (PIP) technique with a microwave heating assistance. The microwave heating temperature was 1100 °C, 1200 °C, 1300 °C, and 1400 °C, respectively. Microstructures, flexure properties, and fracture behaviors of the composites were investigated. The KD II SiCf/SiC composites exhibited higher flexure properties and improved non-brittle fracture characteristics than those of the KD-I SiCf/SiC composites. The differences in the flexural properties, fracture behaviors and microstructures between the KD-I and KD II SiCf/SiC composites were discussed based on the tensile properties of the SiC filaments and the interfacial bonding statues in the composites.

Micelle plays an important role both in scientific research and practical applications. However, the problem about the state of micelle interior has not been completely solved. Based on the molecular dynamics (MD) simulation, absolute configurational entropies of hydrophobic chain are calculated to give a correct description of micelle hydrophobic interior. N-dodecyl betaine (NDB) and n-tridecane (C13), which have the same number of methylene group, are investigated in the present study. Results including total entropy, translational entropy, rotational entropy as well as vibrational entropy are calculated and compared between alkyl chains of NDB micelle and liquid C13. Local entropies along NDB alkyl chain and those between micelle and C13 are also considered. Through these comparisons, we explicitly propose that innermost groups of hydrophobic chains, where carbon number is no more than two, are identical to pure alkane whilst the outer core in the micelle shows the liquidlike state at the molecular level. The detailed information of micelle interior is the foundation for understanding micelle applications, such as solubilization, drug delivery and catalysis.

In order to improve the thermal conductivity and full-fill the gaps between the fiber bundles for three-dimensional four-directional (3D4d) braided SiCf/SiC composites, 500 nm submicron-sized β-SiC particles were introduced into the 3D4d preform by an electrophoretic deposition (EPD) method. ζ-potential of the KD-Ⅱ SiC fibers and the aqueous suspension of the β-SiC particles were analyzed, as well as the efficiency of the deposition. After densified via PIP process, microstructure, three-point bending strength and thermal conductivity of the composite were investigated. The results showed that, SiC particles filled the gaps between the SiC fiber bundles efficiently, and thermal conductivity of the composites fabricated through PIP process assisted by EPD was 2.3 times that of the composites fabricated via PIP only. The bending strength of the EPD-composites was 647.08 ± 69.53 MPa, which decreased to 2/3 of that of the composites manufactured only by PIP, owing to the reduction of fiber volume fraction and the damages to the interface coatings and fibers under the action of the electric field.

To deeply study the variation mechanisms of mechanical properties, flexural modulus of SiC fibers reinforced SiC matrix (SiC/SiC) composites prepared by conventional and microwave heating at 800 °C–1100 °C was discussed in detail. The elastic modulus of fibers and matrix, interface bonding strength and porosity of SiC/SiC composites were considered together to analyze the changing tendencies and differences in their flexural modulus. The elastic modulus of fiber and matrix was determined by nanoindentation technique and interface characteristics applying fiber push-out test. The porosity and microstructure examinations were characterized by mercury intrusion method, X-ray Diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). Moreover, two conflicts between the changing trends of elastic modulus and chemical compositions of composite components were focused and explained. Results indicate that three factors played different roles in the flexural modulus of SiC/SiC composites and residual tensile stress in composite components led to the conflicts between their elastic modulus and chemical compositions.

Development of broadband absorption materials for solar energy harvesting is an important strategy to address global energy issues. Herein, it is demonstrated that an ultrablack silicon structure with abundant surface texturing can absorb about 98.7% solar light within the wavelength range of 300 to 2500 nm, i.e., a very large range and amount. Under 1 sun irradiation, the ultrablack silicon sample's surface temperature can increase from 21.2 to 51.2 °C in 15 min. During the photothermal water evaporation process, the ultrablack silicon sample's surface temperature can still reach a highest temperature of 43.2 °C. The average photothermal conversion efficiency (PTCE) can be as high as 72.96%. The excellent photothermal performance to the excellent light-trapping ability of the pyramidal surface nanostructures during solar illumination, which leads to extremely efficient absorption of light, is attributed. In addition, the large water contact area also enables fast vapor transport. The stability of the photothermal converter is also examined, presenting excellent structure and performance stabilities over 10 cycles. This indicates that the ultrablack Si absorber can be a promising photothermal conversion material for seawater desalination, water purification, photothermal therapy, and more.

Insufficient catalytic activity and stability, and high cost are the key barriers for Pt-based electrocatalysts in wide practical applications. Herein, a hierarchically porous PtNi nanoframe/N-doped graphene aerogel (PtNiNF-NGA) electrocatalyst with outstanding performance toward methanol oxidation reaction (MOR) in acid electrolyte has been developed via a facile tert-butanol-assisted structure reconfiguration strategy. The ensemble of the high-alloying-degree-modulated electronic structure and correspondingly the optimum MOR reaction pathway, the structure superiorities of hierarchical porosity, thin edges, Pt-rich corners, and the anchoring effect of the NGA, endow the PtNiNF-NGA with both prominent electrocatalytic activity and stability. The mass and specific activity (1647 mA/mgPt , 3.8 mA/cm2 ) of the PtNiNF-NGA are 5.8 and 7.8 times higher than those of commercial Pt/C, respectively. Especially, it exhibits exceptional stability under a 5-hour chronoamperometry test and 2200-cycle cyclic voltammetry scanning. This work is of high inspiration for the design of Pt-based electrocatalysts with both high activity and stability.

Efficient exfoliations of bulk molybdenum disulfide (MoS2 ) into few-layered nanosheets in pure phase are highly attractive because of the promising applications of the resulted 2D materials in diversified optoelectronic devices. Here, a new exfoliation method is presented to prepare semiconductive 2D hexagonal phase (2H phase) MoS2 -cellulose nanocrystal (CNC) nanocomposites using grinding-promoted intercalation exfoliation (GPIE). This method with facile grinding of the bulk MoS2 and CNC powder followed by conventional liquid-phase exfoliation in water can not only efficiently exfoliate 2H-MoS2 nanosheets, but also produce the 2H-MoS2 /CNC 2D nanocomposites simultaneously. Interestingly, the intercalated CNC sandwiched in MoS2 nanosheets increases the interlayer spacing of 2H-MoS2 , providing perfect conditions to accommodate the large-sized ions. Therefore, these nanocomposites are good anode materials of potassium-ion batteries (KIBs), showing a high reversible capacity of 203 mAh g-1 at 200 mA g-1 after 300 cycles, a good reversible capacity of 114 mAh g-1 at 500 mA g-1 , and a low decay of 0.02% per cycle over 1500 cycles. With these impressive KIB performances, this efficient GPIE method will open up a new avenue to prepare pure-phase MoS2 and promising 2D nanocomposites for high-performance device applications.

B4C&ndash, TiB2 composite ceramics with ultra-high fracture toughness were successfully prepared via spark plasma sintering (SPS) at 1900 &deg, C using B4C and Ti3SiC2 as raw materials. The results showed that compared with pure B4C ceramics sintered by SPS, the hardness of B4C&ndash, TiB2 composite ceramics was decreased, but the flexural strength and fracture toughness were significantly improved, the fracture toughness especially was greatly improved. When the content of Ti3SiC2 was 30 vol.%, the B4C&ndash, TiB2 composite ceramic had the best comprehensive mechanical properties: hardness, bending strength and fracture toughness were 27.28 GPa, 405.11 MPa and 18.94 MPa&middot, m1/2, respectively. The fracture mode of the B4C&ndash, TiB2 composite ceramics was a mixture of transgranular fracture and intergranular fracture. Two main reasons for the ultra-high fracture toughness were the existence of lamellar graphite at the grain boundary, and the formation of a three-dimensional interpenetrating network covering the whole composite.

B4C-TiB2 composite ceramics with ultra-high fracture toughness were successfully prepared via spark plasma sintering using B4C and 30 vol.% Ti3SiC2 as raw materials at different sintering temperatures. The results show that compared with pure B4C ceramics sintered by SPS, the flexural strength and fracture toughness are significantly improved, especially the fracture toughness has been improved by leaps and bounds. When the sintering temperature is 1900 ℃, the B4C-TiB2 composite ceramic has the best comprehensive mechanical properties: hardness, bending strength and fracture toughness are 27.28 GPa, 405.11 MPa and 18.94 MPa·m1/2, respectively. The main two reasons for the ultra-high fracture toughness are the formation of TiB2 three-dimensional network covering the whole composites, and the existence of lamellar graphite at the grain boundary.

To study the optical properties of background atmospheric aerosols in East China, we carried out observations of the physical, chemical and optical properties of atmospheric aerosols at the summit of Mount Tai (Mt. Tai, 1533.7 m above sea level) from 13 May to 25 June 2017. The results show that the average scattering coefficient ( &sigma, sca , 550 ) at 550 nm of the aerosols at the summit of Mt. Tai is 40.3 Mm&minus, 1, and the average absorption coefficient ( &sigma, abs , 550 ) at 550 nm is 16.0 Mm&minus, 1. The complex refractive index of aerosols is a key parameter for aerosol retrieval and modeling. There are few studies on the equivalent complex refractive index of aerosol in the Taishan area. We calculated the aerosol equivalent complex refractive index using the observed aerosol scattering coefficients, absorption coefficients and particle size distribution data, providing more data support for future modeling in this region. The real part (n) of the complex refractive index at 550 nm of aerosol ranges from 1.31 to 1.98 (mostly under 1.50), with an average value of 1.38, while the imaginary part (k) ranges from 0.014 to 0.251 (less than 0.10 for over 95% samples), with an average value of 0.040. The analysis of the n and k of the aerosol average complex refractive index shows that the scattering properties of the aerosols at the summit of Mt. Tai are relatively weak and the absorption properties are relatively strong when compared with those of other kinds of aerosols. The k of the aerosol complex refractive index at the summit of Mt. Tai has strong correlations with the wind speed, temperature, as revealed by the correlation analysis.

van der Waals (vdW) heterostructures generated by stacking of graphene with other two-dimensional (2D) crystalline sheets have produced a new class of "designer" materials which shows great promise for nanoscience and nanotechnology. However, the 2D sheets are obtained either from nature or synthesized by high-energy procedures, which preclude the design of their structures as well as properties from molecular design on demand. Here, we introduced a rationally designed 2D polymer (one-monomer unit thick, freestanding network composed of periodically linked monomers) as a component for heterostructure construction, and created a 2D polymer-graphene heterostructure. The heterostructure has a high chemical stability, and could be thermally stable up to 400 °C. In the heterostructure, the 2D polymer doped graphene without changing its intrinsic structure, leading to the enhancement of its electric conductivity by a factor of ∼2.5. This piece of work opens the door to tune the properties of graphene heterostructures with rational design for specific applications.

The packing state and structure of monolayer at the air/water interface have important effect on its wide application. Using molecular dynamics (MD) simulation, phase transitions of sodium dodecyl sulfate (SDS) monolayer, dependent on the surface area per molecule, have been studied in the view of configuration entropy. With the reduction of surface area per molecule, three two-dimensional (2D) phases are defined, including gaseous, liquid expanded and liquid condensed phases. At small surface area per molecule, the 2D monolayer will collapse and 3D aggregates are formed in the bulk solution. We give a detailed description of the collapse mode from interfacial monolayer at the air/water interface to micelle in the solution at the molecular level. Using the quasi-harmonic (QH) approximation, the entropic change of SDS for 2D phase transition are first introduced, which is around −29.7 J mol−1 K−1 for the transition from 2D gaseous film to 2D liquid expanded film and −42.0 J mol−1 K−1 for the transition from 2D liquid expanded film to 2D liquid condensed film. The effect of different surface coverages on the dynamical and structural properties of SDS monolayer at the air/water interface is evaluated. Based on simulated results, a schematic diagram of 2D monolayer in different phases is proposed.

A kind of particle with “tremella-like” surface and core-shell structure was synthesized by pyrolysizing polycarbosilane (PCS). The “tremella-like” surface was mainly composed of graphene, which perpendicularly grew on the nucleus. The nucleus was composed of polycrystalline SiC, in which β-SiC nano-crystal randomly dispersed in amorphous matrix. This kind of particle was believed to have a great potential in the electromagnetic wave absorbing material application, because it had a huge specific surface area, core-shell structure, electromagnetic wave absorbing SiC core. The formation mechanism of this kind of particle was also discussed. It was thought that this kind of particle was derived from the small PCS molecules released during the pyrolysis of PCS precursor. Moreover, the carbon atoms participating in the growth of graphene was believed to separate out from the SiC nucleus at higher temperature.

Efficient preparation of single-layer two-dimensional (2D) transition metal dichalcogenides, especially molybdenum disulfide (MoS2), offers readily available 2D surface in nanoscale to template various materials to form nanocomposites with van der Waals heterostructures (vdWHs), opening up a new dimension for the design of functional electronic and optoelectronic materials and devices. Here, we report the tunable memory properties of the facilely prepared [6,6]-phenyl-C61-butyric acid methyl ester (PCBM)–MoS2 nanocomposites in a conventional diode device structure, where the vdWHs dominate the electric characteristics of the devices for various memory behaviors depending on different surface deposition ratios of PCBM on MoS2 nanosheets. Both nonvolatile WORM and flash memory devices have been realized using the new developed PCBM–MoS2 2D composites. Specially, the flash characteristic devices show rewritable resistive switching with low switching voltages (∼2 V), high current on/off ratios (∼3 × 102), and...

To study the shear mechanical properties and deformation mechanism of the interface between cemented soil and warm frozen soil, the key parameters are provided for the design and evaluation of cemented soil structure in warm frozen soil ground. In this study, a series of negative temperature direct shear tests of the cast-in-place cemented soil-frozen soil interface were conducted under the influence of different factors. The binary medium model was used to investigate the mechanical stress and deformational mechanisms of the interface, and the damage rate and stress sharing rate functions were introduced. Assuming that the strength of each element of the interface obeyed the Weibull probability distribution, the constitutive equation of the warm frozen soil-cemented soil interface was established. The results showed that the stress-displacement curve of the interface was a strain-softening type, and the entire deformation process of the interface was divided into four stages: the linear elastic, elastic-plastic, softening, and residual stability stages. The constitutive model based on the binary medium theory revealed the micro stress–strain mechanism of the interface and better described the entire stress–displacement process of the interface and the strain softening phenomenon, which can provide a basis for the numerical simulation and theoretical calculation of the structure in the frozen soil ground.

Designing cost-effective, highly active, and durable platinum (Pt)-based electrocatalysts is a crucial endeavor in electrochemical hydrogen evolution reaction (HER). Herein, the low-content Pt (0.8 wt%)/tungsten oxide/reduced graphene oxide aerogel (LPWGA) electrocatalyst with excellent HER activity and durability is developed by employing a tungsten oxide/reduced graphene oxide aerogel (WGA) obtained from a facile solvothermal process as a support, followed by electrochemical deposition of Pt nanoparticles. The WGA support with abundant oxygen vacancies and hierarchical pores plays the roles of anchoring the Pt nanoparticles, supplying continuous mass transport and electron transfer channels, and modulating the surface electronic state of Pt, which endow the LPWGA with both high HER activity and durability. Even under a low loading of 0.81 μgPt cm-2 , the LPWGA exhibits a high HER activity with an overpotential of 42 mV at 10 mA cm-2 , an excellent stability under 10000-cycle cyclic voltammetry and 40 h chronopotentiometry at 10 mA cm-2 , a low Tafel slope (30 mV dec-1 ), and a high turnover frequency of 29.05 s-1 at η = 50 mV, which is much superior to the commercial Pt/C and the low-content Pt/reduced graphene oxide aerogel. This work provides a new strategy to design high-performance Pt-based electrocatalysts with greatly reduced use of Pt.

Improving the utilization of energy in the electrochemical hydrogen evolution reaction (HER) is a meaningful but challenging task. Coupling the HER with electro-Fenton instead of oxygen evolution is an effective method. For high-efficiency electro-Fenton, herein, the electron structure of CoP/C was optimized due to the doping of Fe to improve the carrier density of CoFeP/C and produce more hydroxyl radicals (·OH), which was confirmed by both characterization and density functional theory calculation (DFT) analysis. Meanwhile, CoP/C exhibits excellent HER activity with an overpotential of 42.1 mV (vs. RHE) at 10 mA cm−2 and a Tafel slope of 59 mV dec−1 because of the favorable electron transfer vector spiny structure and the high content of P element. The electrochemical flow reactor employing CoP/C for cathodic H2 and adopting CoFeP/C for anodic electro-Fenton requires only a low constant voltage of 1.68 V. For optimal electrode adjustment, electro-Fenton can be considered as an ideal oxidation reaction to promote the energy efficiency in the rationally designed reactor. Combination HER with electro-Fenton supports that our designed reactor has high potential in the fields of sustainable energy and environmental remediation.

Trace amounts of solvent additive can effectively regulate the phase-separated morphology of the active layer composed of donor and acceptor materials for improved power conversion efficiency (PCE) of polymer solar cells (PSCs). However, applicable solvent additives for PSCs are still limited, and it is difficult to rationally design or select appropriate solvent additives for optimal morphology control of the active layer, mainly due to the lack of sufficient understanding of the morphological regulation mechanism. Here, on the basis of a series of bromine-terminated additives with different chain lengths, we systematically investigated the relations between properties of solvent additives, active layer morphology, and photovoltaic performance of PTB7:PC71BM bulk heterojunction PSCs. In addition to the widely acknowledged requirements of solvent additives with selective solubility toward one of the components in the active layer and remarkably higher boiling point than that of the host solvent, it was fo...

Multimodal imaging nanoprobes are urgently sought because they can integrate different imaging function into individual nanoplatform and provide more comprehensive and accurate information for the diagnosis of early-stage tumor. Lanthanide-based upconversion nanoparticles (UCNPs) are regarded as promising nanoplatforms to fabricate these probes. Herein, we firstly developed the active core-active shell structured NaYbF4:Tm@NaGdF4:Yb-PVP UCNPs with the average diameter of 13.23 ± 0.96 nm as multimodal imaging probes. These water-dispersible nanoprobes presented excellent near-infrared to near-infrared (NIR-to-NIR) upconversion luminescence (UCL) performance, which is favorable for optical bioimaging due to deeper tissue penetration and autofluorescence reduction. After coated with the NaGdF4:Yb active shell, the UCL emission intensity at 800 nm increased by 7.2 times. These nanoprobes exhibited a desirable longitudinal relaxivity (r1 = 3.58 L/(mmol s)) and strong X-ray attenuation property (58.84 HU L/g). The cytotoxicity assessment, histology analysis and biodistribution study revealed that NaYbF4:Tm@NaGdF4:Yb-PVP UCNPs had relatively low cytotoxicity and negligible organ toxicity. These UCNPs were applied for NIR-to-NIR UCL imaging in vivo. More importantly, the detection of small tumor was successfully achieved under T1-weighted MRI and CT imaging modalities after intravenous injection of these UCNPs. These results revealed that NaYbF4:Tm@NaGdF4:Yb-PVP UCNPs could serve as promising NIR-to-NIR UCL/MRI/CT trimodal imaging probes.

Transition metal oxides with large specific surface area are attractive for high-activity catalysts, and hierarchical structures of transition metal oxides with porous feature possess the structural advantage in the transfer of gaseous reactant and product. In this work, porous Cu–Mn oxides with high surface area were successfully obtained through low-temperature coprecipitation method in alcohol/water solvent and then post-annealing. The addition of alcohol showed great influences on the shape and catalytic performances for CO oxidation. Dumbbell-like Cu–Mn oxide particles with splitting ends displayed high catalytic activity and a complete conversion of CO was achieved at 45 °C, suggesting a shape-dependent catalytic activity. The oxidative activity was attributed to a combination of factors including specific surface area, active surface oxygen species and Mn(IV) cations. The results may supply a new thought to design high-performance Cu–Mn oxide catalysts.

Silicon nitride (Si 3 N 4 ) foams were prepared by using protein foaming method with varying rotating speed during the foaming process. The pore sizes of these as-fabricated Si 3 N 4 foams were measured by means of the Image Pro Plus software and the as-measured pore size date was analyzed statistically by using the SPSS Statistics software. It was indicated that the pore size data of the as-prepared Si 3 N 4 foams abided by the logarithmic normal distribution. With the increase of rotating speed, the pore structure of Si 3 N 4 foam became more uniform. This was because of the enhancing shear stress at higher rotating speed, which increased frequency of collision between bubbles in foamed slurry and hence improved the uniformity of bubble size distribution. The porosity, density and flexural strength of these as-prepared Si 3 N 4 foams fluctuated in a small range, indicating that the rotating speed had limited influence on these properties.

Recent developments in the physics of high-index resonant dielectric nanostructures suggest alternative mechanisms for subwavelength light control driven by Mie resonances with a strong magnetic response that can be employed for the design of novel optical metasurfaces. Here we demonstrate metasurfaces based on nanoimprinted perovskite films optimized by alloying the organic cation part of perovskites. We reveal that such metasurfaces can exhibit a significant enhancement of both linear and nonlinear photoluminescence (up to 70 times) combined with advanced stability. Our results suggest a cost-effective approach based on nanoimprint lithography and combined with simple chemical reactions for creating a new generation of functional metasurfaces that may pave the way toward highly efficient planar optoelectronic metadevices.

Recently, hybrid halide perovskites have emerged as one of the most promising types of materials for thin-film photovoltaic and light-emitting devices because of their low-cost and potential for high efficiency. Further boosting their performance without detrimentally increasing the complexity of the architecture is critically important for commercialization. Despite a number of plasmonic nanoparticle based designs having been proposed for solar cell improvement, inherent optical losses of the nanoparticles reduce photoluminescence from perovskites. Here we use low-loss high-refractive-index dielectric (silicon) nanoparticles for improving the optical properties of organo-metallic perovskite (MAPbI3) films and metasurfaces to achieve strong enhancement of photoluminescence as well as useful light absorption. As a result, we observed experimentally a 50% enhancement of photoluminescence intensity from a perovskite layer with silicon nanoparticles and 200% enhancement for a nanoimprinted metasurface with silicon nanoparticles on top. Strong increase in light absorption is also demonstrated and described by theoretical calculations. Since both silicon nanoparticle fabrication/deposition and metasurface nanoimprinting techniques are low-cost, we believe that the developed all-dielectric approach paves the way to novel scalable and highly effective designs of perovskite based metadevices.

With the development of bone tissue engineering, it is a great challenge to fabricate a bioactive surface which can provide a favourable microenvironment for cell adhesion, migration and osteo-differentiation. Coating the as-prepared substrates with bioactive components is an effective method to induce osteogenesis. In this study, we designed a multi-layered hybrid coating containing hydroxyapatite nanoparticles, heparin and chitosan. Heparin is used to mediate the electrostatic assembly of hydroxylapatite nanoparticles with chitosan, as well as the subsequent recombinant human bone morphogenetic protein-2 (rhBMP-2) loading. Several independent pieces of evidence were provided to indicate the successful fabrication of the hybrid coating. Sustained release of rhBMP-2 by this coating was also achieved. The in vitro biological studies reveal that the hybrid coating system has excellent biocompatibility and can improve the osteo-differentiation especially for rhBMP-2 present on the coating surface. The results demonstrate that the proposed rhBMP-2 loaded hybrid coating can provide a favourable osteogenic microenvironment and has the potential to improve in situ bone repair due to its superior osteoconductivity as well as osteoinductivity.

The cathode interfacial layer (CIL) plays a vital role in enhancing the efficiency and lifetime performance of bulk heterojunction (BHJ) polymer solar cells (PSCs). Here, we compared the use of various organic semiconducting molecules, tris(8-hydroxyquinolinato) aluminum (Alq3), bathocuproine (BCP) and 1,3,5-tri(m-pyrid-3-yl-phenyl)benzene (TmPyPB), as CILs in PSCs and analyzed their influence on device performance. Compared to the inorganic LiF CIL-based PSCs, significantly higher photovoltaic performance was observed by using these organic CILs in both PTB7:PC71BM and P3HT:PC61BM PSCs. Specifically, TmPyPB CIL-based devices exhibit superior device stability and high power conversion efficiency (PCE) up to 7.96%. A systematic study on the effects of Frontier orbital energy levels, surface morphology, and electron mobility of CILs suggests that a relatively coarse interface morphology would be helpful in the formation of high-density interfacial defect states for efficient electron extraction and a high mobility is of central importance in facilitating electron collection for high PCEs. Moreover, a synergistic effect between the inorganic LiF and organic molecules in the dual-CIL could contribute to the further enhancement of PSC efficiency (8.01%) and ambient stability. This work reveals fundamental principles in regulating the functions of CILs and would hopefully promote the investigation and development of ideal organic CILs for high-performance PSCs.

SiC/SiC composites coated with the pyrolytic carbon (PyC) interphase coatings of different thickness were fabricated by polymer infiltration and pyrolysis (PIP) process using microwave sintering at 1100 °C assisted with the hot mould pressing pressure of 3 MPa. The effects of the PyC coating thickness on the densification, the flexural properties and microstructures of the fabricated SiC/SiC composites were investigated via the mercury intrusion test, the computed tomography (CT) technique and scanning electron microscopy (SEM). The results indicate that the preforms coated with thinner PyC coatings, which have better flexibility under the hot mould pressing process, bring SiC/SiC composites with higher densification degrees, due to their better flexibility under the hot press moulding process. Simultaneously, thicker PyC coatings result in weaker interphase debonding between SiC fibers and matrix quantified by the single fiber push-out test. Too thick or too thin PyC coatings both make against the flexural properties, as they will cause the debonding between SiC fibers and matrix too early or too late. The PyC coating thickness-0.20 μm is approximate for the better flexural properties.

Clean and efficient exfoliation of bulk MoS2 into single- or few-layered nanosheets in the pure semiconducting hexagonal phase (2H phase) remains a great challenge and becomes a bottleneck for the intensive studies and applications of MoS2-based nanomaterials. Here, a new method for the scalable synthesis of 2H-MoS2 nanosheets using liquid nitrogen (L-N2) exfoliation has been developed. After five heating/L-N2 immersion cycles, the produced MoS2 nanosheets are primarily fewer than three layers in the pure 2H phase after the evaporation of the exfoliation reagent of L-N2. Impressively, two-dimensional (2D) van der Waals heterostructures by accommodating organic semiconductive nanoaggregates on the surface of semiconducting 2H-MoS2 nanosheets exhibit excellent electronic rectification effects for a nonvolatile write-once-read-many-times memory behavior with an ON/OFF ratio of over 105. This work with the novel heating/L-N2 exfoliation strategy to prepare clean and pure 2H-MoS2 nanosheets would open up treme...

The concentration and chemical composition of aerosol particles were measured and sampled at two altitudes of Mt. Tai, North China Plain in May and June 2017. Concentrations of ice nucleating particles (INP) were analyzed with a static vacuum water vapor diffusion chamber (FRIDGE-NUIST) in deposition mode after being sampled using an electrostatic aerosol collector. The average INP concentration (1.19 to 3.45 L−1) at Mt. Tai matches with the same measured at Tai’ An (foot of the Mt. Tai, 1.57–3.49 L−1, at RHw = 95%, 97%, 99% and t = −20 °C). Correlations between concentrations of aerosol particles and INP were below 0.5 and less than simultaneous measurements made at Tai'An. Clear diurnal variations at the height of the planetary boundary layer (PBL) resulted in changes in aerosol and INP concentrations at the top of the mountain. We found that EC-Aged (aged elemental carbon) and mineral type particles are clearly associated with ice nuclei when the height of the PBL exceeds the altitude of the mountaintop. Furthermore, we found significant correlations between INP concentrations and concentrations of OC (organic carbon) and Na K (sodium/potassium salt) type aerosol particles at night (in the free troposphere). Ice nucleation active surface site densities are higher at night (22:00 LST, local standard time) than during the day (11:00 LST) due to the change in aerosol characteristics. This study shows that OC and Na K type particles may serve as sources of efficient ice nuclei at night.

Inspired by the practical operation of the fluid machineries, direct numerical simulation of fluid with a lot of finite-size particles flowing around a large-size obstacle at three different Reynolds numbers is implemented by using a two-way coupled finite-volume, discrete-element and immersed-boundary method. The results show that, for a low Reynolds number Re=20, the flow is dominated by viscosity, and under the circumstances of a small Stokes number, the particles follow fluid streamlines closely. The flow suggests regular movement characteristics of laminar flow, although the vortices behind the obstacle tend to collapse under the perturbation of particles. For a moderate Reynolds number Re=100, the phenomenon of vortex shedding is also observed. Due to the centrifugal force induced by the vortices, particles are distributed around the main vortices behind the obstacle, forming particle-free zones in these vortices. For a high Reynolds number Re=300, the flow is chaotic. The vortices of many sizes appear irregularly in the domain and the distribution of particles tends to be uniform.

The physical and chemical characteristics of aerosols have a significant effect on scattering coefficients (σsp). In this research, a single particle aerosol mass spectrometer (SPAMS) and a scanning mobility particle sizer spectrometer (SMPS) were used to measure the chemical composition and size distribution of aerosol number concentration in Nanjing, China. During the observation time, the average σsp varied from 11.64 to 485.84 Mm−1, with an average of 114.16 ± 77.87 Mm−1. For relative humidity greater than 75.0%, the optical hygroscopic growth factor (f(RH)) increased rapidly, with an approximate distribution of 3.41 ± 0.78. During the night of July 15th, 2015, nitrate and sulfate increased by 5.93 and 1.32 times, respectively, compared with daytime values. The peak of the average size distribution of the aerosol number concentration during the observation period (341.0 cm−3) was located in the Aitken mode of 58.3 nm. After particle size conversion from the vacuum aerodynamic diameter to the mobility diameter, the particle size range of the aerosol mass spectrometer ranged from 138.2–723.4 nm, all of which are distributed in accumulation mode. Source apportionment revealed that secondary, biomass, and carbonaceous aerosols are the primary facilitators in 327.8–406.8 nm, accounting for 21.3%, 25.7%, and 33.3%, respectively. The fixed scattering coefficients were calculated using the Mie model, according to the source apportionment of aerosol number concentration for modifying the aerosol refractive index. From July 6th–11th, the calculation and observation results of σsp exhibit excellent consistency and a Pearson coefficient of 0.66. Therefore, the accurate size distribution of the chemical composition and source apportionment of aerosols are of great significance for the simulation of atmospheric optical scattering.

We demonstrated a method for computer-generated holograms fabricated by using a femtosecond Bessel beam. A high-efficiency point-by-point process was used to fabricate a longitudinal modified array with a period of 10 μm and a modified area with diameter of approximately 1.5 μm on transparent glass. Tuning the modified length of each area by changing the relative positions of the Bessel beam and sample allowed the phase profile of the incident light to be flexibly adjusted to generate an arbitrary far-field pattern. The approach was verified by inscribing a designed phase hologram in borosilicate glass. Twin images were eliminated by high-level modulation.

A novel route was developed to fabricate Si 3 N 4 /epoxy composite. In this route, the Si 3 N 4 particles were constructed into the foamed shape by using protein foaming method, firstly. Then the Si 3 N 4 foams were sintered to bond these Si 3 N 4 particles together. Finally, the Si 3 N 4 /epoxy composite was fabricated by infiltrating the epoxy resin solution into the sintered Si 3 N 4 foams. This route was proved to be an efficient way in enhancing the thermal conductivity of epoxy matrix at a low loading fraction. For example, the thermal conductivity of the as-prepared Si 3 N 4 /epoxy composite with a loading fraction of 22.2 vol% was up to 3.89 W m −1 K −1 , which was about 17 times higher than that of neat epoxy.