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In order to slow down the cooling rate of mixture and reduce the low-temperature cracking of asphalt pavement in large temperature difference areas, polyurethane solid–solid low-temperature phase change materials (PSLPCMs) were prepared by prepolymer method in this study. The PSLPCMs were incorporated into hot mix asphalt mixture to prepare PSLPCMs particle asphalt mixture. The pavement performance and phase change temperature control behavior of this special type of mixture were analyzed from the perspectives of particle content and particle size. Studies have shown that PSLPCMs have good phase change thermal storage performance and thermal stability. Different PSLPCMs content and particle size have certain improvement effect on the high temperature stability and low temperature crack resistance of the mixture, and have no obvious adverse effect on the water stability of the mixture. At the same dosage, with the increase of particle size, the improvement effect of PSLPCMs particles on the road performance of the mixture is more obvious. With the increase of PSLPCMs particle content, the specific heat capacity of asphalt mixture increases, and the thermal conductivity decreases. The temperature regulation effect of asphalt mixture shows an increasing trend, and the cooling rate slows down. The PSLPCMs particles with particle size of 1.18–2.36 mm have better improvement effect on the temperature regulation performance of the mixture. When the content of PSLPCMs is 7 wt%, the maximum temperature regulation effect of the mixture reaches 3.4 °C.

Permeable asphalt mixtures are widely used to achieve good permeability of the pavements used for urban road surfaces. Based on the law of water migration in permeable road structures, the water-holding performance of permeable asphalt mixtures was analyzed and the evaluation indexes were determined. Open-graded asphalt friction course (OGFC-13) permeable asphalt mixture was selected, and the changes in the saturation, water retention, and water-holding rate of OGFC-13 permeable asphalt mixtures with different porosities were compared using water-holding equipment. The water-holding characteristics of permeable pavement materials under different seepage conditions were analyzed. A model of the relationship governing the water-holding capacity of the permeable asphalt mixture, water action conditions, and material porosity was established by a linear fitting method, and the reliability of the model was verified by comparison with laboratory test results, providing a foundation for related research on the water-holding and cooling behavior of permeable pavements.

An epoxy resin/powder curing agent crack-repair material (EPCRM) was developed to overcome the limitations of the existing materials used to seal asphalt pavement cracks. The EPCRM was prepared by ...

Soft actuators with perception capability are essential for robots to intelligently interact with humans and the environment. However, existing perceptive soft actuators require complex integration and coupling between the discrete functional units to achieve autonomy. Here, we report entirely soft actuators with embodied sensing, actuation, and control at the single-unit level. This is achieved by synergistically harnessing the mechanosensing and electrothermal properties of liquid metal (LM) to actuate the thermally responsive liquid crystal elastomer (LCE). We create multifunctional LM circuits on the LCE surface using a simple and facile methodology based on magnetic printing. The fluidic LM circuit can not only be utilized as a conformable resistive heater but also as a sensory skin to perceive its own deformation. Moreover, the rational design of the LM circuits makes it possible to achieve biomimetic autonomous actuation in response to mechanical stimuli such as pressure or strain. In addition, the intrinsic stretchability of LM allows us to create 3D spring-like actuators via a simple prestretch step, and complex helical motions can be obtained upon mechanical stimulation. This work provides a unique and simple design for autonomous soft robotics with embodied intelligence.

Wet clutches are widely used in vehicle transmission systems to start and shift. The temperature field of the wet clutch components is influenced by friction and is closely related to the vehicle p...

Studies have shown that reinforced paper-based friction material with 600 µm carbon fiber length possesses a high dynamic friction coefficient but is subjected to abrasive wear during sliding contact. This work is devoted to further investigate the effect of operating variables on this friction material subjected to high operating conditions. A pin-on-disc test was carried out to determine the tribological behavior of this friction material sliding against 65Mn steel. The friction and wear rate results from measurements were discussed. The highest friction value of about 0.3 was obtained by varying the applied load at 120 N while the lowest friction value close to 0.02 was obtained when the sliding speed was 0.026 m/s. Increasing the sliding speed above 0.30 m/s caused constant temperature (175 °C) to fluctuate due to high friction heat generation on the sliding surface. The highest wear rate was 1.42 × 10−15m3/Nm by varying the sliding speed at 1.31 m/s. In contrast, the lowest wear rate was 2.1 × 10−16m3/Nm when the temperature was at 400 °C.

The temperature field of the wet clutch is an important factor that influences the vehicle transmission performance. In order to predict and prolong the service life of the wet clutch, a test bench is built, and an accelerated life test is carried out based on the actual working conditions. Then, according to the variation of the friction coefficient and the maximum radial temperature difference, the sliding temperature field is analyzed in different periods. By introducing four evaluation indexes, a temperature field evaluation system is established and verified. With the help of this evaluation system, the temperature fields during running-in and unstable stages are compared, and the thermal failure mechanism of the friction disc is analyzed. In the stable stage, the influence of rotational speed, oil pressure and lubricant flow on the temperature field are investigated. The results of this study can guide the design and control of the friction components in the wet clutch.

Liquid metal (LM) has shown potential values in different areas. Attempts to implement LM are tending to develop new functions and make it versatile to improve its performance for practical applications. Here, we present an unprecedented LM-integrated ultra-elastic microfiber with distinctive features for wearable electronics. The microfiber with a polyurethane shell and an LM core was continuously generated by using a sequenced microfluidic spinning and injection method. Due to the precise fluid manipulation of microfluidics, the resultant microfiber could be tailored with tunable morphologies and responsive conductivities. We have demonstrated that the microfiber could act as dynamic force sensor and motion indicator when it was embedded into elastic films. In addition, the values of the LM-integrated ultra-elastic microfiber on energy conversions such as electro-magnetic or electro-thermal conversions have also been realized. These features indicate that LM-integrated microfiber will open up new frontiers in LM-integrated materials and the wearable electronics field.

In this paper, the flammability limit of the battery thermal runaway vent gas (BVG) is studied numerically by using the CHEMKIN 2.0 code. The research content mainly includes the change of flammability limit with the state of charge, initial temperature, and initial pressure. The chemical reaction kinetics at the flammability limit is also analyzed. The results show that the flammability limit obtained by numerical simulation is in good agreement with that calculated by Le Chatelier's mixing rule. The lean and rich limits increase with the increase of the initial pressure, and the increasing trend gradually slows down. As for the change of initial temperature, higher the temperature is, wider the limits are. In addition, according to the simulation results, the fitting formula of the flammability limit changing with the initial conditions is given. Furthermore, in order to reveal the important elementary reactions controlling the flammability limit, the sensitivity analysis with respect to the flame speed and heat release rate analysis of the elementary reactions are carried out at the flammability limit. Finally, the effect of CO2 and H2 content on the flammability limit of BVG is discussed.

In this work, we have first investigated the explosion limit behaviors from hydrogen to propane through numerical simulations and validated with the available experimental data. The shape of the explosion limit curves and the possible turning points (P1–2, T1–2), first to second limit transition, and (P2–3, T2–3), second to third limit transition that bound the second explosion limit as a function of the fuel carbon number, have been examined. Results show that with an increase of methane mole fraction in the hydrogen/methane system, the upper turning point (P1–2, T1–2) remains almost unchanged and the lower transition point (P2–3, T2–3) rotates counterclockwise around (P1–2, T1–2). With a further increase of carbon number, (P1–2, T1–2) moves to the lower-pressure and -temperature region and (P2–3, T2–3) gradually moves to the lower-pressure and higher-temperature region. The slope of the second explosion limit is inversely proportional to the carbon number, kPT = 0.0069 – 0.005/(Xc – 0.7), approximately. Second, a sensitivity analysis has been conducted to study the elementary reaction on the second explosion limits. The results show that the chain branching and termination reactions governing the explosion limit of hydrogen have a little effect on the second explosion limit of methane. The C2H5O2H decomposition to form OH radicals is dominant in controlling the nonmonotonic behavior of the second explosion limit of C2H6. The second explosion limit behavior of propane is governed by three sets of reactions in the low-temperature oxidation process.

A one-step synthesis of visible light responsive diatomite/g-C3N4 composite material was prepared by impregnation-calcination method. The products were characterized by Scanning electron microscope, X-ray diffractometer, Ultraviolet diffuse reflectance spectroscopy, Fourier transform infrared spectrometer, and Photoluminescence spectrometer. The SEM results showed that g-C3N4 was successfully attached onto the surface of the diatomite. Also the composite materials were more light-responsive compared with the single phase material. The composite materials had a maximum degradation efficiency up to nearly 91.79%. The significant improvement in photocatalytic performance was due to the porous structure of diatomite, increase of contact area of carbon nitride.

A novel free-standing electrode consisting of nickel phosphide (Ni2P) nanoparticles on nitrogen and phosphorus co-doped porous carbon (NPC) are synthesized on carbon cloth (CC). Polyaniline (PANI) and nickel (Ni) are sequentially electro-deposited on the surface of CC, which are then transformed into NPC and Ni2P by an in-situ carbonization-phosphorization combined process. The electrode surface is distributed with large amounts of uniform macropores, which could expose more active sites and enhance the interfacial exchange with the electrolyte. The Ni2P@NPC@CC electrode delivers early overpotentials of 92 and 280 mV vs. Reversible Hydrogen Electrode (RHE) at 10 mA cm−2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline condition, respectively. The electrolytic cell with Ni2P@NPC@CC electrode both as anode and cathode can achieve 10 mA cm−2 at a small bias of 1.54 V for the overall water splitting. Density functional theory (DFT) calculation indicates that combination with Ni2P and NPC can decrease Gibbs free energy for H* adsorption (ΔGH*) and increase charge density on the interface, thus could lead to the enhanced activity for water splitting. The free-standing and noble-metal free Ni2P@NPC@CC electrode is stable, highly active and cost effective, thus have great potential for the hydrogen production.

Dissimilar joining of 6 mm thick steel/Al butt joints was carried out using a novel laser offset welding process. The effect of the different locations at the interface on the intermetallic compound (IMC) layers of the joints produced by two different laser powers was investigated. Microstructure inhomogeneity of the IMC layers was investigated in terms of phase morphology, thickness, grain size, main component and phase compositions. As a result, the IMC layer at the interface has the same phase types consisting of η-Fe2Al5 and θ-Fe4Al13 phase for the three locations produced by two laser powers. However, the morphology of the θ-Fe4Al13 phases, the grain size and the thickness of the η-Fe2Al5 layers, and the predominant component in the IMC layers is strongly affected by the laser powers and the locations at the interface. The highest UTS of 85.5 MPa is obtained at the middle location due to the formation of the thinner η-Fe2Al5 layers and the minimum amount of θ-Fe4Al13 phases. Decreasing laser energy inputs effectively improves the IMC layer uniformity, and the influence of locations at the interface on the IMC layer thickness will be weakened with further decreasing the energy inputs. The heating temperature at the interface has a very important impact on the thickness of the η-Fe2Al5 layer attributed to the ferrite or austenite phases appeared in the steel substrate affecting the growth rate of the η-Fe2Al5 layers.

Purpose The purpose of this paper is to study friction and wear properties of three types of steels against paper-based friction disc, including 65Mn, 20#steel and 30CrAl, so as to obtain the appropriate working conditions for different friction materials in the transmission system. Design/methodology/approach Based on actual working conditions, pin-on-disc tests are conducted on a universal material tester. The two evaluation indexes, including average friction coefficient and variation coefficient, are introduced to analyze the different friction properties among three types of steel. Furthermore, the temperature-dependent wear pattern and wear depth are subsequently studied. Findings The results show that 65Mn is more suitable for working under heavy load and low velocity, but 30CrAl and 20#steel are suitable for working under light load and high velocity. Moreover, wear primarily occurs on paper-based material and peaks at about 325. Practical implications This research of different materials and friction property for friction pairs is helpful to improve the performance and prolong the service life of transmission systems. Originality/value Suitable working conditions of different friction materials are obtained, and the correlation between wear and decomposition in high temperature is verified.

Polyurethane solid–solid phase change material (PCM) with low phase change temperature is synthesized via prepolymer method. The synthetic polyurethane solid–solid PCM had lower crystallinity than PTMEG2000. The polyurethane solid–solid PCM was still in solid state during the heating process, and no liquid leakage was observed. After many phase change cycles, the polyurethane solid–solid PCM exhibited good stability of phase change cycles. Hence, the asphalt modified by polyurethane solid–solid PCM was prepared by high-speed shearing method. With increasing polyurethane solid–solid PCM proportion, the high temperature deformation resistance of modified asphalt gradually increased. At low temperature ( 3 wt%, the specific heat capacity of the modified asphalt had an evident peak ranging from 13 °C to 25 °C. In the range of the proportion, the coefficient of the heat conductivity of the modified asphalt gradually increased with increasing PCM content. During the cooling process, the modified asphalt cooled relatively slow before the phase transition of the polyurethane solid–solid PCM. With continued decrease in the temperature, the phase transition of the polyurethane solid–solid PCM occurred, and the cooling rate of the modified asphalt further decreased. With increasing polyurethane solid–solid PCM content, the temperature control ability of modified asphalt and the efficiency of temperature control gradually increased.

Although some established electromagnetic particle detectors have been used to detect and distinguish micro-particles in different fields, the adopted particle equivalent model leads to large detection error because that ignores the difference of the magnetic perturbations induced by particles with different shapes and postures. To improve the development of high-precision electromagnetic micro-particle detectors, the magnetic models of particles with different shapes and postures are established. The distribution of magnetic flux density and the magnetic energy change caused by particles are calculated. The theoretical and experimental results illustrate that the change of magnetic energy caused by spherical particles is much lower than that caused by ellipsoidal and flaky particles of the same volume, meanwhile, with the increase of the rotation angle of ellipsoidal and flaky particles, the variation of magnetic energy decreases significantly. Based on the results, precise particle equivalent functions considering the magnetic properties of particles are proposed.

To analyze the latent heat thermoregulation effect of the microencapsulated phase change material (Micro-PCM) on the pavement asphalt mixture, 300 mm × 300 mm × 300 mm outdoor cubic specimen made up of asphalt mixture with the Micro-PCM was prepared. By arranging a sufficient number of temperature sensors inside the specimen, a real-time monitoring system was established to record the temperature variations of the specimen. Two indices, the latent heat accumulated temperature value (LHATV) and latent heat thermoregulation index (LHTI) were proposed to evaluate the latent heat thermoregulation performance of the Micro-PCM under heating and cooling processes. The results showed that the solar radiation and air flow conditions were the important factors affecting the latent heat effect of the Micro-PCM. The responses of the heat transfer process of the Micro-PCM varied at different locations inside the specimen, which caused a difference in the latent heat efficiency. Meanwhile, under the conditions where the ambient temperature changed rapidly, the phase change response inside the specimen would be relatively lagged, the process of latent heat storage was hindered, and the heat couldn’t be completely converted to the latent form. It can be conclude that the excessive heating and cooling rates will affect the process of latent heat, the thermoregulation efficiency of the Micro-PCM can be maintained at a high level under the appropriate variable temperature conditions, a medium temperature range and time span. Under these conditions, the Micro-PCM can exert an effective latent heat thermoregulation function to asphalt mixture.

Phase change material is a high thermal storage substance, which can reduce temperature-related diseases of asphalt pavement when mixed with asphalt mixture. In this paper, NiTi alloy phase change heat-storage asphalt mixture (NiTi APCHAM) are prepared by using equal volume parts to replace fine asphalt aggregates partially with the NiTi alloy phase change energy-storage particles (NiTi APCEP). As the temperature increases, the specific heat capacity of NiTi APCHAM will increase first and then decrease due to the heat-storage effect of NiTi APCEP. The thermal conductivity coefficient of NiTi APCHAM shows a linear increasing trend with the increase in the substitution rate of NiTi APCEP. Adding NiTi APCEP in asphalt mixture can reduce its daily maximum temperature. Increasing admixture of NiTi APCEP in asphalt mixture can help to improve the phase change heat-storage thermoregulation capacity of the mixture. However, at a 6 wt% substitution rate of NiTi APCEP, the latent heat thermoregulation efficiency of NiTi APCEP reaches to maximum. With the increase in the content of NiTi APCEP, the Marshall stability of asphalt mixture gradually increases, and flexural-tensile strain at low temperature decreases gradually. By contrast, the water stability of the asphalt mixture is unaffected by the addition of NiTi APCEP.

Hepatocellular carcinoma development is closely related to the changes in tissue mechanics induced by excess collagen deposition and crosslinking, which leads to liver fibrosis and malignant progression. The role of matrix stiffness has been widely assessed using various linearly elastic materials. However, the liver, like many soft tissues, also exhibits nonlinear elasticity by strain-stiffening, allowing cells to mechanically interact with their micromilieus which has attracted much attention in cellular processes recently. Here, we use a biomimetic hydrogel grafting of GRGDS peptide with tunable nonlinear mechanical properties, polyisocyanides (PIC), to investigate the influence of strain-stiffening on HepG2 liver cancer cell behavior by tuning PIC polymer length. Compared to short PIC polymer with lower critical stress, PIC hydrogels composed of long polymer with higher critical stress promote the motility and invasiveness of HepG2 cells, and induce more actin stress fibers and higher expression level of mechanotransducer YAP and its nuclear translocation. Strikingly, the expression of calcium-activated potassium channel KCa3.1, an important biomarker in hepatocellular carcinoma, is also affected by the mechanical property of PIC hydrogels. It was also shown that downregulating the KCa3.1 channel can be achieved by inhibiting the formation of actin fibers. Our findings imply that the strain-stiffening property of PIC hydrogels affects the expression of KCa3.1 potassium channel via mediating cytoskeletal stress fiber formation, and ultimately influences the liver carcinoma cell functional response. STATEMENT OF SIGNIFICANCE: The effect of nonlinear elasticity by strain-stiffening, is assessed in HepG2 liver cancer cell behavior by using a biomimetic hydrogel with tunable mechanical properties, polyisocyanides (PIC). PIC gels with higher critical stress promote the motility and invasiveness of HepG2 cells and induce upregulated expression levels of KCa3.1 potassium channel and YAP, but which can be suppressed by inhibiting the formation of actin fibers. Our findings imply that the strain-stiffening property of PIC gels influences the expression of KCa3.1 potassium channel via mediating cytoskeletal stress fiber formation and, ultimately affects the liver carcinoma cell functional response. ispartof: ACTA BIOMATERIALIA vol:148 pages:152-162 ispartof: location:England status: published

The understanding and controlling of the restrained shrinkage is critical for the application of ultra high performance concrete (UHPC). This study made an analysis of restrained shrinkage mechanism of four kinds of UHPCs based on the direct tensile test accompanied with acoustic emission (AE) source location, free shrinkage test and restrained shrinkage test. The effects of UHPC tensile properties (strain softening or strain hardening) and high performance calcium sulphoaluminate (HCSA, a new kind of expansion agent) dosages (0%, 3% and 6% by mass of total binder) were investigated. The restrained shrinkage cracking mechanism of strain hardening UHPC and strain softening UHPC was analyzed based on AE analysis method under direct tensile loading. The results indicates that strain hardening UHPC shows multiple micro-defects to relax the restrained tensile stress marginally while strain softening UHPC shows several hairline cracks to relax the restrained tensile stress evidently. In ASTM C1581-04 ring test, the restrained shrinkage of strain hardening UHPC with HCSA dosage of 0%, 3% and 6% at 80d is 141 μe, 96 μe and 16 μe, respectively. The HCSA expansion agent can effectively reduce the restrained shrinkage of UHPC and the influence on the structure.

A “one stop” thermal stabilizer, zinc arginine complex (Zn(Arg) 2 ), with excellent excellent initial whiteness, whiteness retention and long-term thermal stability time for PVC, was conveniently synthesized in water solution. The successful synthesis of Zn(Arg) 2 was confirmed by FTIR, TGA and element analysis. Besides the longer Congo red and static thermal stability time than nitrogen-containing thermal stabilizer reported, Zn(Arg) 2 also had better initial whiteness, whiteness retention and dynamic thermal stability time showed by Congo red test, discoloration test and torque rheology test. Especially, the static thermal stability time was more than 150 min, and the dynamic thermal stability time reached 78 min. The excellent thermal stability effect of Zn(Arg) 2 on PVC was ascribed to the simultaneous possession of three mechanisms: absorbing HCl, replacing labile chlorine atoms and complexing ZnCl 2 . Moreover, PVC with Zn(Arg) 2 also showed excellent transmittance tested by vis-uv-near infrared spectrophotometer. Therefore, Zn(Arg) 2 is a “one stop” thermal stabilizer with good application prospects in transparent PVC.

The comprehensive fault diagnosis method has been developed to analyze the failure of the multi-disc clutch. The mechanical buckling model is developed to investigate the relationship between the resistance torque and the periodic circumferential bright spots. The contact pressure and temperature on the friction surfaces are obtained with the consideration of the concentrated reactive load of the circlip. The friction and wear characteristics of the friction disc under different temperature conditions are explored by the pin-on-disc test, and then the surface morphologies of tested discs are observed by the metalloscope. The results demonstrate that both the thermal buckling and the mechanical buckling can result in the mechanical-thermal buckling. As the temperature varies from 15 °C to 400 °C, the disc experiences the abrasive wear, ploughing wear, adhesive wear and delamination wear in order. Finally, the mechanical-thermal safety boundaries are proposed. Moreover, the paper provides some suggestions for better design of clutch: the circlip should be optimized to avoid stress concentration; the teeth number of separate plates should be increased to improve the torque transmission capacity; the thickness of separate plates should be different which can be determined by their axial positions in the clutch pack.

Purpose This paper aims to study and compare the friction stability of wet paper-based clutches with regard to the radial grooves (RG) and waffle grooves (WG). Design/methodology/approach This paper presents an experimental study of a wet clutch concerning the effect of groove patterns on the friction torque and surface temperature. The friction stabilities of RG and WG are investigated with the applied pressure, rotating speed and automatic transmission fluid (ATF) temperature taken into consideration. Findings The friction torque and surface temperature of WG are larger than those of RG under the same operating condition. The friction torque difference between RG and WG grows with the increase of applied pressure and narrows with the increase of ATF temperature. Additionally, their temperature difference expands via increasing the rotating speed and ATF temperature or reducing the applied pressure; in this way, not only the variable coefficient difference between RG and WG can be narrowed, but also the friction stability of the clutch can be improved dramatically. Originality/value This paper explains the thermodynamic differences between RG and WG; moreover, it is verified experimentally that WG has a better friction stability than RG.

In this work, Ti-Sn-Sb/γ-Al2O3 particle electrodes were prepared and employed for the degradation of oxytetracycline (OTC) by three-dimensional electrocatalytic technology. Factors associated with the preparation of Ti-Sn-Sb/γ-Al2O3 particle electrodes were investigated. The effects of initial concentration, conductivity, pH value, aeration intensity, current density, plate spacing, and particle electrode dosage on OTC removal were studied. The removal rate of OTC and total organic carbon were achieved approximately 92.0% and 41.0% under the optimal operating condition, respectively. In addition, Ti-Sn-Sb/γ-Al2O3 particle electrode was analyzed by Fourier Transform Infrared spectroscopy (FT-IR), scanning electron microscope (SEM), energy dispersive spectrum analysis (EDX), X-Ray Fluorescence Spectrometer (XRF), and X Ray Diffraction analysis (XRD), which indicated that a significant amount of TiO2, SnO2, and Sb2O3 were formed on the surface of Ti-Sn-Sb/γ-Al2O3 particle electrode. It was also observed that the primary function of Ti-Sn-Sb/γ-Al2O3 particle electrode in the three-dimensional electrode electrolysis process is the strong oxidizing function of ·OH for degrading OTC. Consequently, the analysis of degradation products of oxytetracycline (OTC) demonstrates. In addition, the results and conclusions of this study provide a methodological basis and engineering practice basis for removing the low concentration of antibiotics in water.

Considering the spline friction, the dynamic model of a multidisc clutch is established that permits the calculation of the contact pressure and friction torque acting at each friction surface; the...

This study explored the performance of unbound aggregate materials (UAM). Repeated load tests of single-size, two-size mixed, and three-size mixed gravels were conducted using the precision unbounded material analyzer (PUMA) in single-stage loading mode (SSLM) and multi-stage loading mode (MSLM). The permanent deformation and elastic modulus of the first 400 loading cycles were analyzed under the two loading modes. The modulus of PUMA repeated load tests was compared with modulus models of the repeated CBR test and with constant confining pressure (CCP) and variable confining pressure (VCP) models of the repeated load triaxial test. The results of MSLM showed that the permanent deformation of single-size gravel increased rapidly when the loading strength was lower than 340 kPa and then decreased. The maximum permanent deformation of the mixed gravels appeared as the loading strength was lower than 200 kPa. The increment of permanent deformation tended to single-peak with the large-size aggregate. The loading strength only slightly affected the permanent deformation once it reached a certain extent. The initial-stage permanent deformation of SSLM was the main part of the total, and the proportion increased with the increase in loading strength. A slight difference was observed between the single-size and mixed gravel when the loading strength was under 240 kPa. Then, the permanent deformation of single-size gravel increased rapidly. The permanent deformation of MSLM was smaller than that of SSLM. MSLM can improve the carrying capacity of the unbound materials and reveal the principle of three-stage compaction for UAM. Although the calculated equivalent modulus of the full-friction model was lower than those of the existing studies, it presented the same tendency and was appropriate for the calculation of modulus. The elastic modulus of CCP model was the largest among the four models, and the growth rate of elastic modulus was the highest for VCP model. The effect of confining pressure on the modulus increased with increasing loading strength.

Amphiphilic functionalized montmorillonite (MMT) has been employed in hydrophobic compounds delivery systems. In the present study, MMT intercalated by 3-aminopropyl trimethoxysilane (APS) was employed for the delivery of the model compounds of resveratrol (RSV). The structure and surface morphology of APS-MMT were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetry, scanning electron microscopy, and contact angle analysis. The loading and release efficiencies of RSV were also investigated. Our study showed that the aminosilane-modified MMT is promising for use in poorly water-soluble compounds carrier systems owing to their natural and excellent performance.

Phase change materials (PCMs) can effectively adjust the temperature of asphalt pavement and have broad application prospects. Microencapsulated phase change materials (micro-PCMs) can solve the leaking problem of PCMs, which easily occurs during the heating process of the asphalt mineral mixture. This paper is intended to provide two indices to evaluate the temperature regulation effect of micro-PCMs: the latent heat accumulated temperature value (LHATV) and latent heat thermoregulation index (LHTI). The LHATV reflects the thermal regulation capability of micro-PCMs and the accumulation in temperature difference in a certain time range. The LHTI represents the completion degree of latent heat in unit time and unit temperature, and it reflects the efficiency of latent heat thermoregulation. The outdoor cube model test was conducted on two cube models with dimensions of 30 cm × 30 cm × 30 cm. Each cube model consisted of three asphalt specimens with dimensions of 30 cm × 30 cm × 10 cm. The first cube model, which was mixed with 0.3% wt of micro-PCMs, served as the experimental group, and the other cube model without micro-PCMs addition served as the control group. Inside the two cube models, sufficient temperature sensors were placed to monitor the temperature. The analysis results show that there is a transformable relationship between the latent heat time domain and the temperature domain. In the moderate temperature range and time span, the latent heat thermal stabilization of micro-PCMs can be efficient.

Bronze is one of copper alloy materials that have been widely used not only in the Bronze Age, but also nowadays because they are hard, easy to cast and resistant against corrosion. For bronze, tin is commonly used as the major non-copper ingredient of bronze because of many highly desirable characteristics including the fact that metallic tin is not toxic. We find that the tin bronze is a suitable electrode material for non-enzymatic electrochemical glucose sensing in saliva. For electrocatalytic oxidation of glucose on the bronze electrode, a negative potential is applied for proton reduction which creates a temporary alkaline condition. The sensor has a linear range from 0 to 320 μM with the regression equation: i = 11 + 0.015 C (i is the current in μA and C is the concentration in μM) with a correlation coefficient of 0.994. The sensitivity is found to be 480 μA mM−1 cm-2, and the detection limit is 6.6 μM with a signal-to-noise ratio of 3. The electrode is found to be highly selective towards glucose oxidation in the presence of interfering species such as ascorbic acid and uric acid. The electrochemical senor is integrated into a smart toothbrush for monitoring of saliva glucose, which is potentially useful for non-invasive screening of diabetes. Compared with other electrochemical glucose sensors, a naked bronze electrode is used as the working electrode to ensure the robustness of the sensor. No additional reagent is involved for the electrochemical determination of saliva glucose and the electrode can be regenerated simply by mechanically polishing for long-term uses.

A coupled numerical multi-physics model is developed to study the generation and variation mechanisms of friction torque, including fluid lubricating, micro-contact, sliding and heat transfer among the friction components. The engagement experiment is conducted to verify the accuracy of numerical model and investigate the stability of friction torque. The results show that the most significant operating factor affecting the friction stability is the applied pressure, followed by the rotating speed and the ATF temperature. Simultaneously, the operating factors have great influence on the torque response, engagement time and temperature rise. Moreover, the growth model of friction torque can be divided into two categories: one is increasing linearly and the other is concave parabolic rising.

This work aims at evaluating the physical properties, storage stability, and temperature-adjustable performance of asphalt binder modified with microencapsulated phase-change materials (micro-PCMs). Micro-PCMs with melamine–formaldehyde (MF) resin shells and n-tetradecane cores are fabricated through in situ polymerization. The MF resin shell successfully encapsulates the n-tetradecane core. The prepared micro-PCMs have spherical profiles, smooth surfaces, and particle diameters of 100 μm–200 μm. In addition, the micro-PCMs exhibit high phase-change enthalpy and excellent thermal stabilities. A neat asphalt binder is modified with various amounts of micro-PCMs modifiers. The addition of micro-PCMs does not considerably affect the physical properties of the modified asphalt. However, excessive micro-PCMs content will adversely affect the storage stability of asphalts modified with micro-PCMs. The temperature change rate of the micro-PCMs modified asphalt near the phase-transition temperature of the micro-PCMs decreases with the increase in micro-PCMs content. The specific heat capacity of the micro-PCM-modified asphalt shows a large peak near the phase-transition temperature of the micro-PCMs, and the peak value of the asphalt modified with micro-PCMs increases with increasing micro-PCMs content.

Herein, ultra-small molybdenum carbide nanodots encapsulated in nitrogen-doped porous carbon (Mo2C/N-PC) were synthesized by a facile one-pot method. Ammonium molybdate and low-cost starch were used as precursors of Mo2C and C. Ammonium nitrate was selected as a nitrogen dopant, which played multiple roles in the reduction of MoC to Mo2C, nitrogen doping of carbon, and formation of a porous structure with abundant structural defects, thus avoiding the high-temperature reduction by H2/Ar. The optimized Mo2C/N-PC hybrid has a remarkable catalytic activity towards the HER over a wide pH range (0–14). Especially, under alkaline conditions, an overpotential as small as −100 mV vs. RHE could be achieved at 10 mA cm−2, comparable to that of the best Mo2C-based materials. The density functional theory (DFT) calculations revealed that a decreased Gibbs free energy for H* adsorption (ΔGH*) could be obtained by combining Mo2C with N-PC, proving the synergistic enhancement mechanism of nitrogen doping and structural defects. This material contains no noble metals and can be easily synthesized on a large scale; thus, it should have significant potential in hydrogen production.

The outer circlip constraint is a typical way for a wet multidisc clutch to limit the axial displacement of friction components. The pressure transmission mechanism in a clutch, excited by the conc...

Friction and wear performance is one of the key mechanical properties of accident tolerant fuel cladding coatings. In this study, reciprocating sliding wear tests had performed on two types of CrAl and CrAlN coatings with two different Al content ratios and Zr-4. The coefficient of friction, wear depth, and abrasion loss were measured and compared. The results indicated that the CrAl-based coatings improve the wear behavior significantly and nitrogen has an obvious improvement on the wear resistance of the coating. The friction and wear performance was also studied in a water environment. The results show that the presence of water degrade the wear performance of Zr-4 and CrAl coatings but ameliorates the friction and wear performance of CrAlN coatings. The feasibility of depositing ATF coating on conventional Zr-4 substrates to mitigate the influence of grid-to-rod fretting was demonstrated.

Low average temperature, large temperature difference, and continual freeze-thaw cycles have significant impacts on mechanical property of asphalt pavement. Bending test was applied to illustrate the mixtures’ flexural tensile properties under freeze-thaw (F-T) conditions. Experiment results showed that the flexural tensile strength and strain declined as F-T cycles increased; the deterioration of flexural tensile properties decreased sharply during initial F-T cycles but turned smooth after 15–21 F-T cycles. ANOVA showed that F-T cycles, asphalt-aggregate ratio, and gradation had obvious influence on flexural tensile characteristics. Flexural characteristics of AC-13 behaved better than the other gradations. It turned out that the mixtures’ low-temperature bending characteristics were improved when 5.5% optimum asphalt-aggregation ratio or slightly larger AC-13 gradation was applied.

Preparation of phase change materials with higher heat resistance is of great significance for their popularization and application. In this study, based on phase-change microcapsules (micro-PCMs) with epoxy resin as the capsule shell, microcapsules were compounded with different types of epoxy resins to prepare micro-PCMs and epoxy resin composite phase change materials (CPCMs). The results show that by changing the micro-PCMs content in the CPCM, the phase change enthalpy of the CPCM can be flexibly adjusted within the range of 32.41–50.75 J/g. When the Micro-PCMs content was 40%, the 5% weight loss temperature of the CPCM with N, N, N', N'-tetrakis(glycidyl)-1,3-cyclohexanedi(methanamine) (TGCM) was 228.7 ℃. And after heat treatment at 160 ℃ for 30 min, the enthalpy reduction was less than 5%. With the same micro-PCM content, the heat resistance and mechanical properties of the CPCM with TGCM as the matrix are better than with hydrogenated epoxy resin (HBPA).

Under strong winds and at low temperatures, heat loss of hot-mix asphalt mixtures is likely to occur, which leads to temperature segregation. Temperature segregation affects the forming quality and the performance of asphalt pavements. In this study, a phase-change thermal-insulation agent (PCTIA) was prepared for reducing the temperature dissipation. A cooling simulation experiment was performed to test the temperature-dissipation process for an ordinary asphalt mixture and the asphalt mixture mixed with PCTIA (AM-PCTIA). The thermal-insulation effect was analyzed according to the temperature difference and the thermal-insulation extension time. Moreover, two indices&mdash, the thermal-insulation accumulated time difference value (IATDV) and thermal-insulation accumulated time difference index (IATDI)&mdash, were proposed for evaluating the thermal-insulation ability and efficiency. The results indicated that the temperature at the center of the AM-PATIA was 4 &deg, C higher than that for the ordinary asphalt mixture. The insulation time was prolonged by 29.8 min at the ambient temperature of 15 &deg, C. As the ambient temperature increased, the thermal-insulation effect of the PCTIA improved.

Under the comprehensive action of environmental temperature and vehicle loads, asphalt pavement is prone to certain issues, such as high-temperature wheel ruts. Thermally activated shape-me...

Biomolecular imaging using X-ray free-electron lasers (XFELs) has been successfully applied to serial femtosecond crystallography. However, the application of single-particle analysis for structure determination using XFELs with 100 nm or smaller biomolecules has two practical problems: the incomplete diffraction data sets for reconstructing 3D assembled structures and the heterogeneous conformational states of samples. A new diffraction template matching method is thus presented here to retrieve a plausible 3D structural model based on single noisy target diffraction patterns, assuming candidate structures. Two concepts are introduced here: prompt candidate diffraction, generated by enhanced sampled coarse-grain (CG) candidate structures, and efficient molecular orientation searching for matching based on Bayesian optimization. A CG model-based diffraction-matching protocol is proposed that achieves a 100-fold speed increase compared to exhaustive diffraction matching using an all-atom model. The conditions that enable multiconformational analysis were also investigated by simulated diffraction data for various conformational states of chromatin and ribosomes. The proposed method can enable multiconformational analysis, with a structural resolution of at least 20 A for 270-800 A flexible biomolecules, in experimental single-particle structure analyses that employ XFELs.

Temperature changes of pavement structure have significant influence on the internal stress, strain, and deformation characteristics of the pavement structure. For example, rutting occurs in high temperature range and pavement cracks when its temperature is low. This yields failure and reduces the service life of the pavement structure. Phase change material, PCM, which is a new type of additive for pavement engineering, has been studied for regulating the working temperature of pavement structure. By storing or releasing thermal energy via phase change process, the PCM is able to maintain the temperature of pavement structure in a relatively narrow range. In the present study, outdoor asphalt mixture model constructed with and without PCM were established. The outdoor model was directly exposed to the environment and the temperature distribution inside the outdoor model was measured by using temperature sensors. The specific heat capacities of asphalt mixture mixed with and without PCM were determined by calorimetric method, which is simple and reliable. Based on the outdoor asphalt mixture model, the corresponding finite element model was established by using ANSYS, and the temperature distribution inside the finite element model was determined according to the measured specific heat capacity, density, thermal conductivity of the asphalt mixture, and the meteorological data which were used for determining the boundary conditions. Comparison between the calculated and actual measured temperature values was made. The results show that the calculated temperature values had good agreement with the measure ones, based on which the accuracy of material parameters and boundary conditions were validated. The results of the present study can lay the foundation for calculating the temperature field of pavement structure constructed with PCM and investigating the application of PCM in road engineering.

Successful hydraulic fracturing (HF) operation requires an accurate model for simulating the propagation of fractures. In this paper, a novel mechanism for the formation of T-shaped fractures and a three-dimensional propagation simulation for predicting their dimensional parameters prior to HF treatment are presented. Furthermore, a pressure decline analysis model (PDA) is also developed for calculating the dimensional parameters after HF treatment. Experimental results show that the two models can accurately simulate the T-shaped fractures and provide a valid data for the optimization and evaluation of HF treatments.

Studies and applications of microencapsulated phase change materials (MPCM) in asphalt mixtures have shown that these materials have great potential in reducing temperature-induced pavement defects, but the leakage of MPCM due to their poor temperature stability and mechanical properties seriously limits their application in asphalt pavements. To solve this problem, in this study, epoxy resin and MPCM were compounded to enhance the thermal stability and mechanical properties of MPCM. First, the secondary wrapping method and pouring method were used to composite microencapsulated phase change materials with epoxy resin, and the phase change enthalpy of the epoxy composite microencapsulated phase change materials (EMPCMs) was used to evaluate and optimize the compositing method. The results showed that EMPCMs should be prepared using the pouring method. Based on the pouring method, the effects of the epoxy resin type and content on the properties of EMPCMs were analyzed by thermogravimetric (TG), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and heat treatment analyses. The results showed that epoxy resin could be combined with microencapsulated PCMs, thereby improving the thermal stability and mechanical properties of the composite PCMs; however, the wrapping effects of different types and contents of epoxy resin on the microcapsules were significantly different. When bisphenol A epoxy resin (EP3) was used and the content was 50 wt% of the EMPCMs, the enthalpy reached approximately 35 J/g after heat treatment, and the compressive strength and crush value of EMPCMs were 31.1 MPa and 8.6%, respectively, which meet the requirements for high-temperature mixing and transportation, as well as paving and rolling of the asphalt mixture.

Clutch disengaging dynamic characteristics, including the disengaging duration and the variations of friction pair gaps and friction torque, are crucial to the shifting control of an automatic transmission. In the present paper, the influence of lubrication oil (ATF) temperature on disengaging dynamic characteristics is investigated through a comprehensive numerical model for the clutch disengaging process, which considers the hydrodynamic lubrication, the asperity contact, the heat transfer, the spline resistance, and the impact between the piston and clutch hub. Moreover, the non-uniformity coefficient (NUC) is proposed to characterize the disengaging uniformity of friction pairs. As the ATF temperature increases from 60 °C to 140 °C, the clutch disengaging duration shortens remarkably (shortened by 55.1%); besides, the NUC sees a decreasing trend before a slight increase. When the ATF temperature is 80 °C, the distribution of friction pair gaps is most uniform. During the disengaging process, the increase of ATF temperature not only accelerates the change of the lubrication status between friction pairs but also contributes to the decrease of contact torque and hydrodynamic torque. This research demonstrates for the first time, evidence for clutch disengaging dynamic characteristics with the consideration of ATF temperature.

The numerical model is proposed to investigate the micro-contact characteristics of asperity summits; moreover, the influence of groove area on the friction-wear properties of a Cu-based wet clutch is explored by the bench test. With the increase of rotating speed or applied pressure, the differences of the thermodynamic characteristics of clutches with different groove areas gradually narrow. However, reducing the groove area can reduce the wear of friction disc but increase the carbon black. The thermal environment is the worst in the middle of clutch, where friction components are most likely to fail. Therefore, the groove area should be designed based on the axial position of friction discs to optimize the friction-increasing and wear-reducing performance of the clutch.

The constitutive model is the crucial part for the finite element analyses. To study the elasto-plastic properties of unbound granular materials (UGMs) under repeated vehicular loads, an elasto-plastic constitutive model called revised spatially mobilized plane (SMP) was proposed and validated. In this study, the revised SMP model was used for the plastic strain analyses of a typical three-layer pavement structure. To make comparisons, the Mohr-Coulomb and Druck-Prager models were employed for the numerical computation. The results show that plastic tensile and compressive strains in the horizontal and vertical directions appear on the top surface of UGM using the revised SMP model, but no plastic strains are produced by the Mohr-Coulomb and Druck-Prager models. The distribution of plastic strains in the revised SMP model had a good relationship with the actual loading areas under the vehicular loading, which related to the rutting. With the Mohr-Coulomb and Druck-Prage models, a great plastic strain was produced during the first several loading cycles and hardly increased in the following loading cycles, while the plastic strain in the revised SMP model presented an obvious increasing tendency with increased loading cycles. The predicted permanent deformations of the revised SMP, Mohr-Coulomb and Druck-Prage models were 0.557 mm, 0.78 mm and 0.155 mm, respectively. Our work reveals that the Mohr-Coulomb model may over-predict and Druck-Prage model may under-predict the rutting of pavement in early loading stage and the results proved that the revised SMP model had advantages in the description of the plastic strain of UMG under repeated loads.

Modified epoxy resins exhibit a good crack repair functionality but are currently predominantly used in a two-component form, leading to defects in storage and transportation, construction inconvenience, and fluctuations in construction quality. Single-component epoxy resin grouting material can be considered to improve the efficiency and quality of crack repair. In this study, an accelerator capsule was prepared via encapsulation technology, which was compounded with an epoxy resin base solution to obtain a new type of single-component epoxy resin pavement jointing glue. The storage time and curing behaviour under different temperature conditions were tested, demonstrating its good storage stability under the condition of 35℃. The encapsulation of the accelerator did not affect the promotion of the curing reaction after it was broken. The tensile strength, elongation at break, low-temperature crack resistance, and resilience recovery rate were selected to evaluate the road performance of the grouting material. The results indicated that when the amount of accelerator capsule was 3%, the material exhibited good elasticity and toughness, low-temperature crack resistance, and adhesion to the crack wall under low-temperature conditions. Under high-temperature conditions, the five materials exhibited a high resilience recovery rate, which could effectively resist the intrusion of foreign bodies.

We report on water desalination on fabric based on ion concentration polarization (ICP). The use of fabric as the substrate reduces the cost and simplifies the fabrication procedure for water desalination. On the fabric, water is transported and recovered by capillary force without any external pump. Filtration based on the porous structure of the fabric and electrocoagulation purification induced by anodic electrochemical reaction are also integrated. By the fabric-based water desalination, 85% salt in 50 mM NaCl solution is rejected with an applied voltage of 15 V, which demonstrates its potential in water desalination for remote or underdeveloped areas.

Unbound granular material (UGM) is widely used in flexible pavement to carry vehicular dynamic loading with different loading frequencies. In this study, the influence of loading frequency on the mechanical properties of UGM was investigated via repeated load tests using the precision unbound material analyzer (PUMA). The confining stress, plastic strain, plastic strain rate, resilient strain, resilient modulus, and Poisson’s ratio of two granular materials were analyzed at four loading frequencies and two stress levels. The results showed that confining stress, plastic strain, plastic strain rate and Poisson’s ratio decreased as the increase of loading frequency. Resilient strain and resilient modulus did not show obvious trend with loading frequency. Compared with 1 Hz, confining stress of 19 mm gravel at 240 kPa decreased 28.1% at 5 Hz and 33.7% at 8 Hz. The maximum difference of confining stress at 5 Hz, 8 Hz and 10 Hz was only 0.78 kPa. Other indicators showed similar tendency at different loading frequencies. The results reveal that loading frequency has significant influence on mechanical properties of UGM, while the influence becomes small when the frequency exceeds certain value. Moreover, the loading stress and gradation of material had interaction effect with loading frequency. The coefficients of variation of measurement indicators decreased as the increased loading frequency, which suggested that appropriate frequency can help reduce the error of the testing results.

In this study, epoxy resin/polyethylene glycol 2000 composite stereotyped phase-change material (EPPCM) particles were prepared. It was found that the phase change thermal storage properties were almost unchanged after heat treatment when the thermal decomposition onset temperature reached 230 °C according to Differential scanning calorimetry (DSC) analysis and Thermogravimetric analysis (TGA) test. Modified asphalt with increasing particle doping was prepared by high-speed shearing. Dynamic shear rheological (DSR) test, Bending beam rheometer (BBR) test, temperature regulation test and specific heat capacity test were carried out on modified asphalt. The results show that with the increase in EPPCM doping, gradual improvement of rheological properties of modified asphalt appeared, and there was an increasing trend occurred in the temperature regulation effect. The maximum temperature difference reached 4.3 °C and the specific heat capacity of asphalt increased as well.