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In recent years, dozens of high rockfill dams are under construction or planning for hydropower exploration in western China. In dam construction, the mechanical behavior of coarse granular material greatly affects the compatible deformation of dam body. In this article, an indirect in situ density prediction approach for coarse granular material is firstly proposed to solve the technical obstacle on prediction of the material density in thick overburden layer of a dam site in southwest China. Adopting a self-developed large-scale true triaxial apparatus with a special friction-reduction technique, four series of true triaxial tests were then performed to investigate the behavior of a coarse granular material with a maximum particle diameter of 60 mm. Test results show that the peak strength of the material increases together with the increasing confining stress and the increasing intermediate principal stress ratio. The material dilatancy is restricted by both the confining stress and the intermediate principal stress ratio. With the increase in intermediate principal stress ratio, the internal friction angle increases firstly and then decreases slightly, but the slope of stress path reduces gradually. The tested peak states were compared with several well-known strength criteria under the framework of generalized stress, showing a good fitness with the Lade–Duncan criterion and underestimation by the Mohr–Coulomb criterion and the Matsuoka–Nakai criterion. The strength envelope in the π plane shrinks with the increasing confining stress.

Interface dipoles formed at an electrolyte/electrode interface have been widely studied and interpreted using the "double dipole step" model, where the dipole vector is determined by the size and/or range of motion of the charged ions. Some electron transport materials (ETMs) with lone pairs of electrons on heteroatoms exhibit a similar interfacial behavior. However, the origin of the dipoles in such materials has not yet been explored in great depth. Herein, we systematically investigate the influence of the lone pair of electrons on the interface dipole through three pyridine derivatives B2-B4PyMPM. Experiments show that different positions of nitrogen atoms in the three materials give rise to different hydrogen bonds and molecular orientations, thereby affecting the areal density and direction of the lone pair of electrons. The interface dipoles of the three materials predicted by the "double dipole step" model are in good agreement with the ultraviolet photoelectron spectroscopy results both in spin-coated and vacuum-deposited films. These findings help to better understand the ETMs/electrode interfacial behaviors and provide new guidelines for the molecular design of the interlayer. Funding agencies: The Swedish Research Council (project grants no. 2016-05498, 2016-05990, and 2020-04538), The Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University (Faculty Grant SFO Mat LiU no. 2009 00971), The Open Fund of the State Key Laboratory of Luminescent Materials and Devices (South China University of Technology)

C/SiC is one of most important thermal-structural materials for future aeronautical applications, but there is no consensus on the damage mechanism and pattern of it. To identify the failure processes under mechanical load is important to evaluate this material. In this paper, acoustic emission (AE), an effective continuous damage monitoring technique, is used to monitor tensile tests of 2D-C/SiC. An unsupervised clustering method based on the deep fusion of a genetic algorithm and a K-means algorithm is proposed to analyze the AE signals. Pattern recognition analysis of AE data was carried out to describe the evolution of various damage mechanisms during the failure process. According to the features of each class and associated SEM images of the fracture surfaces, a match between AE clusters and fracture mechanisms involved in the process, including matrix cracking, interface failure, interlaminar delamination, fiber breakage and bundle breakage, is established. It is found that the damage evolution of 2D-C/SiC under tensile loading can be divided into four stages at room temperature. The first stage and the third stage are the main development stages of matrix cracking and interface damage. The second stage and the fourth stage are the main damage periods of fiber, fiber bundle and interlaminar delamination. The damage pattern recognition and damage evolution process of 2D-C/SiC composites during tensile test are described.

A D-A-π-A dye (PTZ-5) has been synthesized by introducing a benzothiadiazole (BTD) unit as an auxiliary acceptor in a phenothiazine-based D-π-A dye(PTZ-3) to broaden its spectral response range and improve the device performance. Photophysical properties indicate that the inclusion of BTD in the PTZ-5 effectively red-shifted the absorption spectra by reducing the E gap. However, the device measurements show that the open-circuit voltage (V oc) of PTZ-5 cell (640 mV) is obviously lower than that of the PTZ-3 cell (710 mV). This results in a poor photoelectric conversion efficiency (PCE) (4.43%) compared to that of PTZ-3 cell (5.53%). Through further comparative analysis, we found that the introduction of BTD increases the dihedral angle between the D and A unit, which can reduce the efficiency of intramolecular charge transfer (ICT), lead to a less q CT and lower molar extinction coefficient of PTZ-5. In addition, the ESI test found that the lifetime of the electrons in the PTZ-5 cell is shorter. These are the main factors for the above unexpected result of PCE. Our studies bring new insights into the development of phenothiazine-based highly efficient dye-sensitized solar cells (DSSCs).

This paper is aimed at the problems of abnormal tribological damage and fluctuation of tribological performance in the self-lubricating composite serving in heavy load spherical plain bearing in aerospace field. The Nomex/PTFE fiber reinforced composite was used to carry out a reciprocating block on ring tribological test, investigating the tribological performance of the material and its wear evolution. Results show that the influence of oscillating frequency on material wear is obviously higher than that of load under high load condition (more than 90 MPa or 180 kN). Under a certain load and frequency condition, friction temperature is a key factor to affect wear behavior of the material. Friction heat plays a dominant role in the process of worn out failure of the material. Too high friction temperature greatly weakens the friction and wear performance, resulting in material failure in a short time. Thermal fatigue is the main tribological damage mode of the material under the high load and high frequency condition, with local worn out occurred. This finding was also verified by SEM analysis of the worn surface and wear debris.

Microporous carbon nanospheres (PCNS)-reinforced magnesium (Mg) composites were prepared using polyvinyl pyrrolidone (PVP) as surfactant and PCNS as reinforcement. The influence of PVP treatment and the effectiveness of PCNS on the mechanical properties of Mg-based composites were investigated. The results show that the PCNS can enhance the properties of the Mg matrix. Moreover, the PVP can effectively improve the dispersion of PCNS in the Mg matrix but had a negative influence on the tensile properties of composites. The MgO films with high tensile strength were produced between matrix and reinforcement after removing PVP, which effectively promotes the interface compatibility and improves the properties of the composite. The tensile yield strength and specific strength of PCNS-reinforced Mg matrix composite exhibited 177 MPa and 102.4 &times, 103 N∙m/kg, respectively, which were 77% and 78% higher than those of the Mg matrix.

During the bearing service, a series of microstructural evolutions will arise inside the material, such as the appearance of feature microstructures. The essential reason for the microstructural evolution is the cumulative effect of cyclic stress. The Hertz Contact formula is usually adopted to calculate the internal stress, and there is a correlation between the shape and distribution of the feature microstructure and the stress distribution. But it is insufficient to explain the relationship between the morphology of feature microstructures and the rolling direction, such as specific angles in butterfly and white etching bands. The rolling phenomenon will cause the asymmetry of stress distribution in the material, which is the source of the rolling friction coefficient. Moreover, slipping or microslip will produce additional stress components, which also cause the asymmetry of the stress field. However, there is no experimental or theoretical explanation for the relationship between the asymmetry of the stress field and the feature microstructure. According to the current theory, the appearance of feature microstructures is caused by stress with or without rolling. Therefore, it is of great significance to study the formation mechanism: whether feature microstructures will appear in the uniaxial cyclic compression stress field without rolling. In this paper, uniaxial cyclic compressive stress was loaded into a plate-ball system and a cylinder system. The characteristics of microstructural change of bearing steel (GCr15) were studied. It was found that the hardness of the material increased after the cyclic compressive load, and the inclusions interacted with the matrix material. In the local microregion a white etching area was found, although the scale is very small. No large-scale feature microstructures appeared. Other phenomena in the experiment are also described and analyzed. For example, the production of oil film in the contact area and the changing law of alternating load.

Graphene quantum dots (GQDs) as a shell layer was coated on the surface of silver nanoparticles (AgNPs) to obtain an effective antibacterial composite (GQDs@AgNPs). The structures and antibacterial properties of AgNPs, GQDs, and GQDs@AgNPs were studied. SEM and TEM results indicated that GQDs were coated on the surface of AgNPs. For GQDs@AgNPs, the core size of AgNPs was about 20 nm, and the shell thickness of GQDs was about 5 nm. The formation and antibacterial mechanism of GQDs@AgNPs composite materials were discussed in detail. It showed excellent antibacterial properties for E. coli and S. aureus.

Water-induced shape memory polymers (SMPs) show promising applications in biomedicine, biosensing, anti-counterfeiting and intelligent actuating systems. However, the dual function of shape morphing and color switching has not been achieved in the water-induced SMP system. Herein, a novel water-induced SMP with both color-switching fluorescence behavior and shape memory performance is reported. The material is fabricated by crosslinking poly(vinyl alcohol) (PVA) and pH-responsive fluorescent carbon quantum dots (CQDs). The incorporation of CQDs with PVA not only improves the shape recovery performance but also endows the material with color-switching features. To our best knowledge, such smart ability is first realized in this PVA/CQD SMP system, and this report provides a novel strategy for fabricating smart water-induced SMPs with adjustable shape recovery performance and fluorescence.

Poly(lactic acid) (PLA) represents one of the most promising and attractive bio-based polymers for green packaging. However, toughness, gas barrier and antibacterial properties of pure PLA films cannot compete with those of traditional petroleum-based active packaging plastics. To fill this gap, utilization of excellent chelating properties of phytic acid (PA), functionalized layered double hydroxides (LDHs@PA-Cu(II)) was firstly synthetized via facile deposition and chelation of one-step assembled PA-Cu(II) coordination compounds on the surface of layered clay. Furthermore, LDHs@PA-Cu(II)/PLA nanocomposites were prepared by blending LDHs@PA-Cu(II) and pure PLA via solution casting evaporation process. After adding only 1 wt % LDHs@PA-Cu(II), elongation at break and tensile strength increase by 53.0% and 18.9%, respectively, and the oxygen relative permeability decreases by 28.0%. Due to the strong interface interaction and heterogenous nucleation, the reinforcement effect of LDHs@PA-Cu(II) at low loadings is remarkable. Meanwhile, owing to the antibacterial activity of PA-Cu(II) coatings, the antibacterial rate (against Escherichia coli) of LDHs@PA-Cu(II) exceeds 99.99%. Furthermore, the corresponding LDHs@PA-Cu(II)/PLA nanocomposites also show outstanding antibacterial properties, which will be a promising candidate for active packaging application.

While microbial spore production and germination of bacteria have been widely studied for their applications in animal husbandry, aquatic products, medicine, and food, few studies have investigated their use for the crack-healing of concrete. To effectively heal the cracks in concrete, studies suggest that the rate of sporulation and the germination of bacteria should be sufficiently high. This study investigates the effects of different carbon sources, nitrogen sources, Mn2+ concentrations, and external culture conditions on the sporulation rate and analyzes the effects of the pH value, heat activation, germinants, various cations, and nutrients on the germination of spores. Bacillus cohnii (B. cohnii) is chosen as the bacterium to be mixed in concrete because of its alkalophilic nature. The mineralization activity of spores after germination and the crack-healing capacity of concrete are studied. The optimal culture medium and the optimum external conditions for spore production are obtained. The total cell count and sporulation rate of bacteria obtained on this medium are 3.14 × 109 CFU/mL and 92.6%, respectively, under the optimum external conditions. The optimal pH value for the spore germination of B. cohnii is 9.7. While the cation Na+ strongly stimulates the germination of B. cohnii spores, other cations (such as K+, NH4+, and Ca2+) do not stimulate spore germination. The optimal concentration of Na+ is 200 mM. The germination rate of spores in the control group concrete specimen (room temperature 24°C) was more than 50%, thus suggesting that B. cohnii bacteria can be used in the self-healing of concrete cracks. The mineralization activity test proves that the spores of B. cohnii have a mineralizing function after germination, and the crystals produced by microbial-induced carbonate precipitation (MICP) are of pure calcite. When the crack width of the concrete specimen with spores of B. cohnii is less than 1.2 mm, it can be completely repaired after 28 days of healing.

Aggregation-caused quenching (ACQ) effect, known as the main cause to restrain solid-state luminescence of carbon quantum dots (CQDs), hinders further application of CQDs in white light-emitting diodes (WLED). Here, a complex of CQDs and phthalimide crystals (CQDs/PC) was prepared through a one-step solvothermal method. CQDs/PC prevented CQDs from touching directly by embedding the CQDs in phthalimide crystal matrix in situ, which effectively reduced the ACQ effect. Furthermore, CQDs/PC exhibited multi-peak fluorescence spectra that span the green, yellow and orange spectral regions. Finally, a WLED fabricated based on CQDs/PC achieved a color-rendering index of 82 and a correlated color temperature of 5430 K. This work provides a quick and effective strategy to apply CQDs to WLED.

Recently, graphene aerogels (GAs) have attracted considerable research attention in oil/water separation owing to their remarkable properties. However, the serious stacking of graphene oxide nanosheets (GO) would lead to low adsorption capacity and poor recyclability. For the first time, with alkaline ammonium citrate as reducing agent and nitrogen source, the point-to-face contact between magnetic carbon nanospheres (MCNS) and graphene sheets was adopted to effectively inhibit the aggregation of graphene sheets. Nitrogen-doped magnetic carbon nanospheres/graphene composite aerogels (MCNS/NGA) were fabricated under weakly alkaline conditions by one-step hydrothermal in-situ electrostatic self-assembling strategy. The aerogels have low density, super-elasticity (up to 95 % compression), high specific surface area (787.92 m2 g−1) and good magnetic properties. Therefore, they exhibit adsorption capacity in the range of 187–537 g g−1 towards various organic solvents and oils, superior to most reported materials to date. In addition, thanks to their good mechanical properties, excellent thermal stability and flame retardancy, they can be regenerated by squeezing, distillation and combustion. More importantly, magnetic control technology can be adopted to realize oriented adsorption and facilitate recycling of organic solvents and oils in extreme environments.

A novel electroactive polypyrrole/graphene oxide@graphene aerogel (PGO@GA) was synthesized for the first time by pulse electropolymerization. The off-time in this technique allows polypyrrole (PPy) to go through a more stable structural arrangement, meanwhile its electronic transmission performance is enhanced by immobilizing graphene oxide between PPy chains. Moreover, graphene aerogel provides a three-dimensional structure with high conductivity to protect PPy from swelling and shrinking during the capacitive testing. Under these synergistic effects, PGO@GA presents exceptional capacitive performances including high specific capacitance (625 F g−1 at 1 A g−1), excellent rate capability (keeping 478 F g−1 at 15 A g−1 with retention rate of 76.5%), and excellent cycling life (retaining 85.7% of its initial value when cycling 5000 times at 10 A g−1). Therefore, the strategy adopted by this research provides a good reference for preparing other PPy-based electrode materials applied in the fields of catalysis, sensing, adsorption and energy storage.

Electron transport materials (ETMs) are widely used as interlayers to lower the cathode electrode work function in organic solar cells and organic light-emitting diodes, for example. The usual interpretation for their operating principle is a chemical interaction between the ETM and the electrode, inducing partial or integer charge transfer or collectively an intrinsic dipole moment caused by preferential molecular orientation. Herein, we systematically explore the commonly used ETM bathophenanthroline (BPhen) deposited on a series of conducting substrates. The energetics at the BPhen interface follows the typical integer charge transfer (ICT) model with an extra displacement of the vacuum level by up to -1.4 eV. The extra displacement is ascribed to the "double dipole step" formed by the positive and negative charged species and their induced image charges when they are close to the surface of substrates. After n-type doping the displacement is further increased to -1.8 eV, yielding a larger work function modification than obtained using typical electrolytes and zwitterions as cathode interlayer. Funding Agencies|Knut and Alice Wallenberg Foundation project "Tail of the Sun; Swedish Research CouncilSwedish Research Council [2016-05498]; Swedish Foundation for Strategic ResearchSwedish Foundation for Strategic Research [SE13-0060]; Ministry of Science and TechnologyMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Ministry of Science and Technology, Government of India [2016YFA0200700]; NSFCNational Natural Science Foundation of China [21504066, 21534003]; Swedish Energy AgencySwedish Energy Agency [45411-1]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO Mat LiU) [2009 00971]

In this paper, Gyroid lattice cylindrical shell (LCS) specimens were designed by a newly proposed mapping methodology and were fabricated by selective laser melting (SLM) technology. Their energy absorption and deformation modes were investigated through quasi-static compression tests. A finite element model (FEM) was proposed, which was validated by the experimental results, for a further study on the compressive behavior of the Gyroid LCS. Based on the numerical study, it was found that Gyroid LCS showed superior energy absorption to the hexagonal LCS and triangular LCS with the same density. In addition, a parametric study indicated that main energy absorption factors, namely total energy absorption, specific energy absorption and mean crushing load, were in power function relationship with the relative density. Finally, it was found that thickness gradient and geometric gradient had significant effects on the failure modes of Gyroid LCS under compression. The research in this paper is expected to provide some guidance for the design of energy absorption devices or structures. Keywords: Gyroid lattice cylindrical structure, Energy absorption, Triply periodic minimal surfaces, Quasi-static compression

A dual-targeting drug delivery system (DTDDS) with magnetic targeting and active targeting was obtained to improve the targeting and drug-loading capacity of magnetic drug nanocarriers. An ultraviolet-visible spectrophotometer and flow cytometry were used to investigate the drug-loading and release capacity, cytotoxicity, and inhibition of tumor cell proliferation, separately. Results show that DTDDS has obvious magnetic characteristics, on which the modification amount of folic acid is 64.82 mg g-1. Doxorubicin was taken as a template drug to evaluate its drug-loading capacity, which was as high as 577.12 mg g-1. Good biocompatibility and low cytotoxicity of DTDDS were further confirmed. Moreover, DTDDS can target the folate receptor on the surface of HeLa cells and deliver doxorubicin into HeLa cells, thereby increasing the proliferation inhibition for cancer cells. Therefore, this new dual-targeting drug delivery system shows potential in significantly reducing the toxic side effects of chemotherapy and improving chemotherapy efficiency.

Developing metal–organic framework-incorporated carbon heterostructure (MOF@C) adsorbents with advanced phosphate removal capability is of remarkable significance in satisfying the increasingly stringent wastewater discharge criteria. Nevertheless, the tailored synthesis of MOF@C architectures and related structure-performance modulation remains elusive to date. Herein, we report on the dimensional engineering of MOF@C to prepare ZIF8@single-walled carbon nanotube (SCNT) and ZIF8@reduced graphene oxide (rGO) heterostructures with satisfactory phosphate removal efficiency. The maximum phosphate adsorption capacity of ZIF8@rGO is 491.2 mg g−1, with the largest partition coefficient value of 1900 mg g−1 μM−1 and an initial concentration of 2 mg L−1 under a neutral condition; thus, the prepared heterostructures evidently surpass state-of-the-art adsorbents. The high adsorption capacity is attributable to the two-dimensional graphene support, which provides a more effective surface area for ZIF8 anchoring than that of one-dimensional CNT. Furthermore, phosphate removal on these dimension-engineered MOF@C is examined as a function of pH, system temperature, and coexisting anions. The underlying mechanism is further elucidated via X-ray photoelectron spectroscopy/X-ray diffraction analysis and density functional theoretical simulation; enhanced phosphate removal by ZIF8@rGO is mainly attributable to the ligand exchange between the phosphates and the adsorbent. Our findings can aid the design of multifunctional MOF@C adsorbents for efficient phosphate removal from contaminated waterbodies.

Applying compound parabolic concentrator (CPC) and phase change materials (PCMs) in photovoltaic/thermal (PV/T) systems are effective methods to promote the electrical and thermal performance simultaneously. Much work has intensively investigated the performance enhancement of separate PV/T-CPC or PV/T-PCM system and conducted experiments under lab environment. However, there were few studies devoted to the thermal and electrical performance collaborative improvement especially at an actual outdoor environment. In this study, a compound parabolic concentrating PV/T system integrated with PCM (PV/T-CPCM) is constructed and different parameters are analyzed in an open-air environment. As solar irradiance and ambient temperature vary during the test period, PCM melts from solid to mushy state, and the temperature non-uniformity factor of PV modules/PCM drops from 4.28/1.34 to 1.42/0.66, indicating the PCM obviously improves the non-uniformity of temperature distribution. Set the pump state as OFF-ON-OFF, PV modules temperature firstly rises from 10.6 °C to 33.2 °C, then quickly drops down to 28.5 °C, and after that slowly drops down to 27.1 °C, showing the combination of PCM and liquid cooling is beneficial to further reduce the PV modules temperature. During the pump-on period, the instantaneous thermal, electrical and primary energy efficiency decrease from 19.6% to 5.0%, 4.8%–3.0%, 30.4%–16.8%, and the averaged values are 7.1%, 4.0% and 17.6%, respectively. The maximum primary energy efficiency of the PV/T-CPCM system is about 7.9% and 10.7% higher than that of the separate PV-CPC and PT-CPC system respectively, demonstrating that the PV/T-CPCM system owns superior heat-electricity cogeneration performance.

Heterocyclic phenothiazine has been proven effective in designing organic hole-transporting materials for perovskite solar cells (PSCs) as it has excellent electron-donating property, straightforward synthesis and feasible structure modifications. However, the resulting photovoltaic performance is still unsatisfactory and the long-term stability has not been studied. Herein, we report a couple of phenothiazine based HTMs (PT-H and PH-HP) to investigate the efficacy of a pyridine functionalization on improving film morphology, hole mobility and device performance as well as long-term stability. The covalent incorporation of a pyridine unit in PT-HP doesn’t alter the absorption, emission and energy levels of phenothiazine based HTMs. However, it can effectively facilitate the dispersion of lithium salt additive to form a uniform thin film, which is generally achieved by additional additive of 4-tert-butylpyridine (tBP). This strategy remarkably improves the film quality and stability of spin-coated HTM for application in PSCs. As a result, PSCs based on tBP free PT-HP achieve a power conversion efficiency of 19.09%, significantly outperforming the reference HTM of PT-H (15.20%). More importantly, the stability of PT-HP based PSCs is successfully enhanced. The work paves the way to develop low-cost, efficient and stable phenothiazine based HTMs for PSCs.

Thermal runaway severely affects the lithium batteries under conditions of non-normal forces or thermal abuse. In this study, a novel flame retardant flexible composite phase change material is successfully prepared, and a battery module based on it is designed and experimentally investigated. Herein, paraffin with high latent heat is performed as phase change material, Styrene-butadiene-styrene is employed as the supporting material, expanded graphite is used as the additive for thermal conductivity enhancement, and a flame retardant is utilized to suppress the heat diffusion and resistant flame. Experimental results reveal that a flame retardant flexible composite phase change material with 15 wt% flame retardant can achieve the optimum flame retardant effect, and its limiting oxygen index value can reach 35.9%. The battery thermal management with 15 wt% flame retardant composite phase change material can effectively avoid the heat accumulation of the battery module in the long cycle. In addition, thermal runaway trigger is simulated by heating rod at 200 °C, and the effect of the different composite phase change material modules on thermal runaway spread are compared. The result reveals that the flame retardant flexible composite phase change material could absorb and transfer the heat of the triggered battery timely and promptly, exhibiting a flame retardant effect necessary to avoid thermal runaway of the battery.

As a promising candidate for converting renewables into chemical energy, lithium hydroxide based chemical heat storage (CHS) materials have gained great investigate enthusiasm by virtue of their outstanding storage capacity and long storage lifespan. But salt hydrates still cannot get rid of the inherent shortcomings of poor thermal conductivity, sintering, low hydration rate, and serious heat storage density degradation, Hence, it is highly desirable to create a salt hydrate CHS material that can achieve improved thermal conductivity, heat storage capacity and water storage content while maintaining good cycle stability for efficient utilization of low grade heat and residential heating. Here, we develop a lithium hydroxide composite CHS material with zeolitic imidazolate framework produced graphene-based (ZIF-8/GO) porous carbon templates as the host porous carbon matrix (ZHPCM). This Li/ZHPCM composite has huge storage strength (Max. 1483.8 kJ kg−1), low reaction activation energy and high hydration capacity attribute to the adequate specific surface area and massively porous of ZHPCM, which not only boosts the spreading of lithium hydroxide, but also assuages the sintering of lithium hydroxide, thus increasing the conversion rate of LiOH to LiOH·H2O, and ultimately lead to an improvement in the storage strength. Moreover, compared to lithium hydroxide, this Li/ZHPCM composite shows remarkable cycle property for 15 times of hydration conversion without conspicuous weakened and good thermal conductivity. Besides, the calculated energy barrier that Li/ZHPCM(800)-50 (35.7 kJ mol−1) needs to overcome is also significantly lower than that of lithium hydroxide (50.7 kJ mol−1), which not only implies that the resistance to the reaction of Li/ZHPCM(800)-50 is smaller, but also further proves the important role of ZHPCM(800) in improving the performance of lithium hydroxide. This novel LiOH composite CHS material may paves a new way for residential heating and the further application of ZHPCM in the future.

Novel current-carrying contact pairs were designed in this study, consisting of an inner raceway, outer raceway, and elastic ring. The effect of rotation speed on the current-carrying tribological properties was investigated using a rolling tribometer. As the rotation speed increased from 240 r/min to 600 r/min, the total friction force in the steady-state period increased from 3.8 N to 7.6 N, and the contact resistance decreased from 0.52 Ω to 0.34 Ω. Scanning electron microscopy and optical microscopy revealed that high rotation speeds and the presence of a current promoted surface fatigue and the generation of cracks. The X-ray photoelectron spectroscopy results indicated that more nascent metals were exposed on the rolling surface at higher speeds, which is beneficial for the electric contact. Compared with previous rigid rolling pairs, the weight of the elastic ring was significantly reduced, and no arcing occurred at high rotation speeds. These results can provide a reference for the design of new high-speed rotating conductive joints.

In response to the fact that not all rolling balls are laden when the angular contact ball bearing working under the condition with certain combined loads especially when the axial preload is not large enough, an analytical method for the determination of the time-varying stiffness of angular contact ball bearing considering the effect of time-varying number of laden balls and load distribution is proposed in this paper. According to the definition of the stiffness, the time-varying stiffness under different sets of combined loads is obtained by the implicit function derivation method. Only the principal diagonal elements of the stiffness matrix are studied for the sake of simplicity. Several numerical examples are simulated and the simulation results indicate that the time-varying number of laden balls and load distribution have a significant effect on the stiffness. The period of the time-varying stiffness is consistent with the time required for the cage to rotate the angle between the adjacent rolling balls. The calculation of the ball bearing quasi-static model and the analytical method for the determination of the stiffness is verified by the existing references.

Terephthalic acid (H2TP) is initially unveiled to be the first example of organic anodes exhibiting the universal Li-ion, Na-ion and K-ion storage capabilities. In Li-ion half cells, H2TP can deliver the average capacities of ∼235 mAh g−1 for 500 cycles; In Na-ion half cells, H2TP is reported to deliver the average capacities of ∼200 mAh g−1 for 50 cycles; and in K-ion half cells, H2TP can exhibit the average capacities of ∼240 mAh g−1 for 150 cycles. At the same time, the chemical structure and crystal structure of H2TP could be transformed into its related metal salts on the anode side due to the low reduction potential. This work indicates that organic electrode materials should own the universal metal-ion-storage (e.g., Li+, Na+, K+, etc.) capability for their large void room of organic solid/crystal state.

The electrostatically controlled deployable membrane antenna (ECDMA) is expected to become one of the next generation spaceborne antennas due to its lightweight, large-aperture and high-precision advantages. However, form-finding of the ECDMA is a challenge that related to the cable-membrane structure and electrostatic force. This paper presents an extended force density method (EFDM) that identifying the equivalent cable force density to replace the orthotropic membrane element stress by the virtual work principle. Then the force density equilibrium equations of the cable-membrane electrode structure and the membrane reflective surface of the ECDMA are deduced based on the EFDM and the corresponding form-finding strategies are given, respectively. Simulations and experiments show that the EFDM presented in this paper is effective for the form-finding design of the ECDMA.

The characteristics of the worn surface of a pin were studied in the presence of a DC magnetic field. The experiments were conducted on a pin-on-disk tribometer in the ambient atmosphere. The mediu...

Zhundong coal, rich in the Alkali and Alkaline Earth Metal elements, causes severe ash deposition during the combustion in many power plants. In this paper, the influence of vermiculite, as an additive, on ash deposition formation and the corrosion phenomenon caused by ash deposition are investigated in a drop tube furnace system. The formation process of ash deposition under real working condition can be simulated in this furnace system. The results show that vermiculite has a significant inhibition effect on the formation and growing process of ash deposition, as well as the corrosion phenomenon. At the beginning of ash deposition, the swelling vermiculite can effectively absorb the SO2 in the flue gas, which restrains the formation of Na2SO4 in the inner ash, close to the surface of heat exchangers. The mineral in internal inner ash gets changed and the phenomenon of corrosion on the heat exchangers surface gets alleviated. Meanwhile, the external inner ash presents with loose structure instead of the molten condition, which lowers possibility for ash deposition to grow. In outer ash deposition, close to the flue gas, the content of layered particles with high melting point, as Mg2SiO4, increases and viscous particles, like Ca2Al2SiO7, are separated from each other by the force of the vermiculite swelling. As a result, adding vermiculite makes it hard for ash deposition to form and grow. According to the experiments, with more than 5% blending ratio of vermiculite, the vermiculite additive has a positive effect on restricting the ash deposition.

Black cotton soils (BCSs) were stabilized with various percentage of lime, natural volcanic ash (VA) and their combinations. The laboratory tests were performed to evaluate the influence of the stabilizers on the physical-mechanical properties of BCS. These laboratory tests included Atterberg limits, California bearing ratio (CBR), swell percent and unconfined compressive strength (UCS). The changes of minerals were also derived by performing X-ray diffraction, Infrared spectroscopy and scanning electron microscope, which were employed to explain the stability mechanism of BCS together with pH test. Results revealed that the added stabilizers improved greatly the physical-mechanical properties of BCS. The use of combinations of lime and VA showed superior results when compared with the single stabilizer. BCS can meet the performance requirements of roadbed materials referring to JTG D30-2015 just by mixing with 3% lime and 15% VA. The increased pH of the stabilized BCS indicated that solubility of the silicate and the aluminate increased, which accelerated the pozzolanic reaction between clay soils and stabilizers. The intrinsic lamellar structures of clay mineral were destructed in the reaction process. Moreover, several new minerals were produced to stabilize the soil fabric. Overall, the use of VA can reduce the consumption of lime in BCS stabilization and actualize the utilization of vast resources BCS as a low-cost roadbed material.

A one-pot microwave-assisted hydrothermal approach was developed to quickly synthesize yellow fluorescent carbon dots (CDs) using o-phenylenediamine and urea as raw materials. The optimized reaction temperature of 140°C and reaction time of 10 min were adopted to synthesize the CDs with photoluminescence quantum yield of 4.23%. The as-prepared CDs exhibit yellow fluorescence (λem ∼ 563 nm) and an excitation-independent PL emission in the region of 440–700 nm. The CDs were combined with a blue chip (λex = 420 nm) to fabricate white light-emitting diodes (WLEDs) and realize white light emission. The WLED has the color coordinates of (0.30, 0.30) and the correlated color temperature of 7915 K, which is suitable for office and outdoor illumination. The results demonstrate that as-obtained CDs can be a promising candidate as yellow-emitting phosphors for WLEDs.

Laser based direct energy deposition is an additive manufacturing method that can produce or repair fully dense components. Maraging steels are well known for its superior strength and toughness with low carbon content. Here, 18Ni300 maraging components were fabricated by laser based directed energy deposition under argon atmosphere. The influence of processing parameters on the forming quality was studied based on orthogonal experiment and the results showed that the macroscopic forming generally performed well and the density of forming parts was positively correlated with laser energy density. The effects of different heat treatments on microstructure evolution and mechanical properties were explored after an hour of solid solution treatment in 830 °C and aging treatments for 1 h, 4 h, 7 h, 10 h respectively. It was found that with the extension of aging time, the directional dendritic columnar crystals transformed into lath martensites and the number of stomas decreased considerably. Meanwhile, the microhardness and tensile properties of the forming parts were promoted greatly after the heat treatments.

High-speed transportation tools demand durable and effective friction materials for practical applications. In this work, we developed a copper-based powder metallurgical friction material via spark plasma sintering, and studied its tribological performances subjected to different braking conditions. Using inertial braking test bench and temperature measuring instrument, average friction coefficient, instantaneous friction coefficient and temperature near friction surface of the material in braking process were tested at two initial speeds (28, 69 m/s) and three contact pressures (0.4, 0.6 and 0.8 MPa). The wear rate of materials was calculated accordingly. Results show that under the same exerted pressure, the average friction coefficient and wear rate at the high speed are smaller than those at the low speed. At the high test speed, the high friction temperature leads to an obvious decrease in instantaneous friction coefficient when the braking process reaches a certain stage. Based on the friction surface morphology analysis, the adhesive wear on the surface has been reduced because of the formation of oxide films at the high speed and surface oxidation wear gradually increases as the pressure increases.

To eliminate the toxic effect of chemotherapy drug of lobaplatin (LBP) on body tissue in liver cancer therapy, this work prepared a nanodrug carrier based on polyethylene glycol-modified carbon nanotubes (PEG–CNTs) and then constructed a targeted drug delivery system (LBP–PEG–CNTs) by loading LBP on PEG–CNTs. Fluorescein isothiocyanate (FITC) was used to label PEG–CNTs to observe the cellular uptake of PEG–CNTs. In addition, the inhibitions of LBP–PEG–CNTs on HepG2 cells were investigated. The results show that the FITC-labeled PEG–CNTs have good cell penetrability; meanwhile, LBP–PEG–CNTs have good stability, pH-controlled release property, and high inhibition rate on HepG2 cells. To be specific, 80% of LBP is released under physiological conditions of liver cancer cells at pH 5.0, and LBP–PEG–CNTs show a high inhibition rate of 77.86% on HepG2 cells, demonstrating that they have targeted, pH-controlled release and inhibition properties on HepG2 cells.

Limited by applicable force-detection techniques, imaging of electronical or magnetic properties on sub-10 nanometer scale with scanning force microscopy in ambient is challenging in experiment and...

Contact force between pantograph and contact wire presents periodic variation with the running of trains. In this paper, the effects of dynamic contact force on friction coefficient and wear rate of pure carbon strip were studied on a pin-on-disk test rig with coupling and decoupling tests. Coupling results showed that the best tribological properties were obtained at 80 km/h. Decoupling results suggested that the increasing amplitude resulted in the production and extension of cracks and severe arc erosion; the increasing frequency contributed to the formation of the oxide film at low arc rate phases. This paper studied the detailed electrical wear behaviors of pure carbon strip and the related mechanism. The results may provide some practical guidance for railway operation.

Effects of lanthanum (La) as micro-alloying element on the hot deformation behaviour of the high strength Mn-Cr-Mo bainitic rail steel were investigated under a range of deformation conditions. The results indicate that La increases the flow stress by 10–30 MPa through strengthening nanoscale strain induced precipitation (SIP) θ-(Fe,La)3C during hot deformation. The hot deformation activation energy increases by 10–40 kJ/mol due to the “Zener effect” of SIP and the dynamic recrystallization (DRX) is retarded due to the competitive behaviour between SIP and DRX. Bainite plates in the DRX domain can be refined by adding La, resulting in the improvement of hot workability. The DRX domain with peak power dissipation efficiency of 52% is determined to be the optimal processing region for Mn-Cr-Mo-La bainitic rail steel.

An enhanced model based on the ideal adiabatic model has been proposed in this paper where the regenerator heat loss is investigated based on some new assumptions and various loss mechanisms including the loss of heat and pressure in heat exchangers are considered as well, at the same time, amounts of governing equations have been obtained according to the above method, which are calculated to show a convergent PV figure that presents the compression/expansion processes. Besides, the thermal efficiency is presented as functions of volume ratio at different circumstances, including various temperature differences and phase differences. It is found that the function relationship between thermal efficiency and volume ratio is not monotonic and there exists a peak value. Furthermore, the result is analyzed based on genetic algorithm and optimum values of volume ratio corresponding to the maximum thermal efficiency at different heater and cooler temperatures have been listed in this paper.

By cutting γ-graphyne along different directions, two kinds of γ-graphyne nanodots (γ-GYNDs) can be acquired. In present study, using the γ-GYNDs we theoretically designed and investigated the spin-dependent transport properties of two kinds of molecular magnetic tunnel junctions (MMTJs). Depending on the orientation of γ-GYND and the connection way between γ-GYND and electrodes, our results show that two kinds of MMTJs have different microscopic transport mechanisms. Significant single or dual spin-filtering effects, giant magnetoresistances (reach 108%) and spin negative differential resistances can be observed in the MMTJs. In addition, the spin-polarized optoelectronic properties of the MMTJs have also been discussed, and the results indicate that the spin-polarized photocurrents are dependent on the polarization direction of light and magnetization directions of the electrodes. Especially, two different light-generated spins can be simultaneously produced in the MMTJs if the incident photons have given energies and they flow along opposite directions. The above findings show that the γ-graphyne-based MMTJs can be used as spintronic devices or opto-spintronic devices.

A simple and green synthesis of fluorescent carbon dots (CDs) was achieved by a microwave-assisted hydrothermal method using potato starch as the carbon source. CDs with a maximum quantum yield of 2.46% were prepared by hydrothermal treatment of a 1 mg/mL starch solution at 220 oC for 30 min. Nitrogen doped CDs (N-CDs) were obtained under the same conditions using starch and ethylenediamine as the carbon and nitrogen sources, respectively, and their quantum yield was twice that of the undoped CDs. Both the CDs and N-CDs exhibit excellent water solubility and good thermal stability, emit blue fluorescence under UV light, but the fluorescent intensity of the latter is obviously higher than that of the former. Two white light-emitting diodes using the CD/starch composite and N-CDs as the phosphors emit yellowish white light and white light, respectively with xy coordinates of (0.38, 0.45) and (0.33, 0.35) in the Chromaticity Diagram of the Commission Internationale de L'Eclairage, suggesting that they have great potential application in optoelectronic devices.

The collapse characteristics and energy absorption capability of composite tubes with different fibers and matrix were studied in present article under axial quasi-static and impact crushing conditions. The sensitivity to fibers, matrix and loading conditions were thoroughly discussed for the crushing modes and energy absorption capability. Experimental results showed specimens with different matrix and fibers exhibit three typical types of crushing modes. Specimens G803/3234 and G827/3234 had better energy absorption performance than the specimens with 5224 matrix. Impact loading condition led to lower energy absorption capability as compared to quasi-static loading condition. Moreover, impact loading condition also caused the crushing mode transition from splaying mode to fragmentation mode for G803/3234 and G827/3234.

The industrial application of burning Zhundong coal has been directly restricted due to severe ash deposition. To attain the wide utilization for this coal, experiments about the effects of different additives on ash deposition were conducted in a drop-tube furnace. The properties of ash deposits were characterized by ICP-OES and XRD, and mineral properties were also calculated by molecular dynamics from the perspective of elemental reactions. The results indicate that ash deposition can be divided into inner layer and outer layer. The deposited layer and the size of particles under vermiculite additive are looser and bigger than those under raw coal and kaolin additive. Additionally, ash deposition for the inner layer is thinner, and ash ratio for the outer layer is higher under vermiculite additive. The total deposited layer may be thinner under kaolin additive, but the inner layer for ash deposition is denser than that under vermiculite additive. Ash deposition for raw coal is mainly caused by the form...

Cable-membrane structures are widely employed for large space reflectors due to their lightweight, compact and easy package. In these structures, membranes are attached to cable net, serving as reflectors themselves or as supporting structures for other reflective surface. The cable length and membrane shape have to be carefully designed and fabricated to guarantee the desired reflector surface shape. However, due to inevitable error in cable length and membrane shape during the manufacture and assembly of cable-membrane reflectors, some cables have to be designed to be capable of length adjustment. By carefully adjusting the length of these cables, the degeneration in reflector shape precision due to this inevitable error can be effectively reduced. In the paper a shape adjustment algorithm for cable-membrane reflectors is proposed. Meanwhile, model updating is employed during shape adjustment to decrease the discrepancy of the numerical model with respect to the actual reflector. This discrepancy has to be considered because during attaching membranes to cable net, the accuracy of the membrane shape is hard to guarantee. Numerical examples and experimental results demonstrate the proposed method.

Biofilm carriers and effective microorganisms (EMs) are both important to improve the decontamination performance of biofilms for wastewater. The decontamination performance of biofilms using polyester (PET), polyvinyl alcohol (PVA), carbon fibers (CFs) and electrochemically-treated CFs as biofilm carriers for EMs were investigated by comparing the concentrations of the chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) of wastewater at different stages of decontamination. The use of all carriers efficiently prevents the loss of mobile EMs. The use of CFs increases the decontamination efficiency. Electrochemically-treated CFs perform best, and the corresponding biofilm has a strong resistivity to the surrounding environment and achieves 97.1%, 92.5% and 96.0% removal rates for COD, TN and TP, respectively, which are 5%–67% higher than those obtained using PET and PVA as carriers.

In the process of laser additive manufacturing, the transmission efficiency of laser energy and the forming quality are influenced by the plasma which plays a fundamental role in coupling the incident radiation to the material. The aim of this work is to present an effective spectral diagnosis method for quality research in laser additive manufacturing. A spectrum acquisition system for direct metal deposition (DMD) was established by using fiber optic spectrometer to collect the radiation during the forming process under different process parameters. The relationships between laser powers, powder feeding rate, traverse speed, and the radiation intensity of the plasma were found. Meanwhile, special wavelengths were chosen to establish the time-domain diagram (the relationship between the intensity and time) corresponding to the process, and some forming defects caused by the changes of processing parameters were correlated with the spectral information. What is more, to diagnose the defects automatically, statistical process control (SPC) method was used to analyze the correlations between intensity fluctuation and the forming defects. The findings of the paper will be helpful to understand the formative mechanism and influencing factors of laser-induced plasma during laser additive manufacturing and lay the foundations for automatic quality control of laser additive manufacturing process.

Zhundong coal as a high quality steam coal has not been widely utilized due to severe fouling and slagging problems during combustion. It is crucial to reveal the slagging and fouling mechanisms in a boiler burning Zhundong coal. In this paper, the properties of ash deposits collected from various heat transfer surfaces in a 330 MW boiler were characterized by ICP-OES, SEM−EDX, and XRD. These results were also verified by an experiment burning Zhundong coal in a drop-tube furnace and thermodynamic calculation by the software FactSage. The results indicated the ash deposited on different heat transfer surfaces in 330 MW boiler burning Zhundong coal could be classified into silicates and sulfates based on their elemental and mineral analysis. Further, the ash deposited on the division panel superheater is obviously divided into three layers. In the first layer, wollastonite and sodium silicate are the main minerals with the contents of quartz and feldspar being relatively small. The types of mineral in the second layer are the same with the first layer, but their contents are different from the first layer. Meanwhile, the amount of crystalline phase in the third layer is lower than that of the first and second layer. In addition, the temperature of the flue gas or the tube played an important role in the mechanism of ash deposition. Thermodynamics calculation also shows CaSO4 can be formed at all temperatures and there only exists CaSiO3 formed in the range 900–1200 °C. The ash deposits along the flue gas flow attributes to sulfates, silicates and sulfates, respectively. The result of the thermodynamic calculation is in accordance with the experiment results obtained in the drop-tube furnace.

Carbon microspheres (CMSs) as a core material had been coated by two capsule walls: an inorganic material of magnesium hydroxide (MH) as inner shell layer and an organic material of poly (ethylene terephthalate) (PET) as outer shell layer. MH coating CMSs (MCMSs) were fabricated by liquid phase deposition method, then grafted 3-Aminopropyltriethoxysilane (APTS) to obtain the Si-MCMSs. Microencapsulated Si-MCMSs (PMCMSs) was prepared by in situ polymerization method. Morphology structure, dispersion, flame retardant and other properties of PMCMSs have been investigated. A series of PET blends were prepared by melt compounding. The results showed that MH and PET as two layers were coated on CMSs surface with the optimal thickness of about 70 nm. The PMCMSs owned better dispersion in PET matrix. Compared with MCMSs/PET composites, the mechanical property of PMCMSs/PET composites had significantly increased because of the strong interface binding force between PMCMSs and PET matrix. Moreover, PMCMSs was proved to be an effective flame retardant. For PMCMSs/PET with 2 wt% PMCMSs, the limiting oxygen index (LOI) value increased from 21.0% (pristine PET) to 27.2%, and the peak heat release rate (pk-HRR) decreased from 513.22 kW/m2 to 352.14 kW/m2. The decreased smoke production rate (SPR) and total smoke production (TSP) values demonstrated PMCMSs suppressed the smoke production. The increased Fire performance index (FPI) value illustrated PMCMSs significantly reduced the fire risk of PET. Overall, the two capsular walls endowed the PMCMSs/PET composites with good mechanical and flame-retardant properties.

The diffraction beam characteristics of tapered-platform fiber are demonstrated by theoretical analysis and experimental measurement. The tapered-platform fiber is designed and fabricated. Based on light ray theory, the Gauss beam lens conversion model is established and the outgoing beam of the tapered-platform fiber end-face is analyzes. The transmission characteristics at the near field and far field spatial distribution of the tapered-platform fiber are measured with visible light, which are showing the evolution of tapered-platform fiber in optical transmission and mode spot. A CCD based video zoom microscope system is built to record cone optical fiber diffraction, and the diffraction pattern of tapered-platform fiber diffraction field in different locations is tested. The results show the diffraction field of tapered-platform fiber is Gauss beam, this research will provide important reference to the application of tapered-platform fiber.

The cytotoxicity of polyethylene glycol-modified carbon nanotubes (PEG-CNTs) on human embryonic kidney cells (293T) and hepatoma cells (HepG2) was studied in vitro. The effect of the concentration of PEG-CNTs on the cell activity and survival rate was detected by a colorimetric assay method after exposure for 24, 48 and 72 h. The dead HepG2 cells obtained by incubation in solutions with different concentrations of PEG-CNTs for 24 h can be stained by a dye, propidium iodide, and the cell mortality was determined by flow cytometry. Results show that the toxicity of PEG-CNTs with a good water solubility towards 293T and HepG2 cells increases with increasing PEG-CNT concentration. When the concentration of the PEG-CNTs is less than 100 μg/mL, the toxicity of the PEG-CNTs is Grade I (non-toxic) and when it is greater than 100 μg/mL but less than 200 μg/mL it is Grade II (mildly toxic), according to the ISO2109932-5 cytotoxicity standard. The toxicity grade does not change with increased time.

The pivotal of organic Rankine cycle (ORC) promotion and optimization is revealing the thermodynamic relationship between cycle configuration, condition and its working fluid properties. Different from the traditional numerical calculation method (TNCM) of ORC, a new thermodynamic cycle separating method (TCSM) is introduced in this paper. Then, efficiency of ORC is conducted expediently by TCSM where Triangle cycle ( η TC ), Carnot cycle ( η CC ) and Brayton cycle ( η BC ) efficiencies are regarded as variables, that is, η SORC = f ( η TC , η CC , η BC ) . When comparing with TNCM, TCSM not only has the acceptable precision for all the investigated 21 working fluids, but also the influence of critical temperature, molecular complexity of the working fluid and superheat degree as well as the reduced operating conditions of ORC can be revealed qualitatively and quantitatively. Finally, three conclusions are revealed: (1) Relationship between ORC limited efficiency (the reduced evaporating temperature of 0.9) and critical temperature of working fluid is revealed; (2) When superheat degree increases, ORC efficiency of dry fluid decreases and wet fluid increases linearly, while the variation of isotropic working fluid remains constant; (3) If the reduced temperatures of two different working fluids are equal, the corresponding efficiencies are equal too. The proposed thermodynamic cycle separating method provides an approach for working fluids selection and performance prediction of ORC.