Search

The effective means to solve material wear is to develop self-lubricating composite materials with excellent tribological, thermal, and mechanical properties. Herein, the composites of reduced graphene oxide (r-GO) nanosheet decorated with Silicon Carbide (SiC) were facilely prepared with employing a silane coupling agent, and the corresponding r-GO/SiC/thermosetting polyimide (r-GO/SiC/TPI) nanocomposite films were obtained by in situ polymerization method. The mechanical, tribological, and thermal properties of these nanocomposite films were investigated. When the content of r-GO/SiC was at 1.0 wt%, the compression strength and compression modulus of the composite increased by 37.7% and 47.3%, respectively, which were much higher than that of TPI composites addition of r-GO or SiC alone. Furthermore, r-GO/SiC/TPI composites also exhibited the lowest wear rate and friction coefficient in these reinforced TPI nanocomposites. When the content of r-GO/SiC was 0.8 wt%, particularly, the friction coefficient and wear rate of r-GO/SiC/TPI decreased by 22.8% and 79.8% compared to pure TPI, respectively. Additionally, trace amount r-GO/SiC hybrids also significantly enhance the thermal stability of TPI matrix. Compared to the polyimide composites reinforced by common nano-scale inorganic fillers, the outstanding mechanical and tribological properties of this r-GO/SiC/PI composites could be attributed to the ball on plane structure of GO/SiC, which lead to crack reflection, strength increment. These r-GO/SiC/TPI composites demonstrate the promising potential to be used as high-performance tribological materials in industry applications.

Due to the abundant reserves and low cost of sodium resources, sodium metal batteries (SMBs) can be used as a promising energy storage technology with high energy density. Recently, ultralow-concentration electrolytes (ULCEs) with 0.3 mol/L (M) NaPF6 are greatly attractive because of their low cost and high permeability. However, the cycle life and rate performance of SMBs in ULCEs are limited by the high reactivity of sodium metal anodes. Here, an acetamide additive, N, O-bis(trimethylsilyl) trifluoroacetamide (BSTFA), is introduced into an ULCE (0.3 M NaPF6 in EC/PC, 1:1 vol %) for stabilizing the electrolyte and fabricating a highly conductive interface in SMBs. Theoretical and experimental results prove that BSTFA can scavenge HF and H2O in the NaPF6-based electrolyte spontaneously and inhibit the hydrolysis reaction of NaPF6. Owing to protective interface layers on sodium metal anode and Na3V2(PO4)3 (NVP) cathode, the Na||NVP battery in 2% BSTFA-containing ULCE shows a high-capacity retention rate of 92.63% after 1955 cycles at 2 C and a superior rate capability of exceeding 105 mAh g−1 at 40 C.

Magnesium-based alloys are appropriate materials for transportation applications owing to their high strength-to-weight ratio. However, the poor corrosion performance of Mg alloy limits its lifetime. In this study, the pure Al coating was deposited onto an AZ91D substrate by cold spraying, and then modified by friction stir-spot-processing. The interfacial microstructure and phase were studied in detail, and the effect of the intermetallic compounds on the microhardness and corrosion properties of the coatings was investigated. Results show that the sound and dense coatings were obtained after friction stir-spot-processing at 2400 and 2700 rpm. Al12Mg17 was found in the upper part of the 1/2 radius zone in the processed coating. The thin and thick IMCs were identified at the interface in the center and 1/2 radius areas, respectively. In the thick IMCs, mainly two types of multi-phase coexistence structures were observed. The four-phase coexistence structure dominated by Al3Mg2 revealed a higher microhardness than the three-phase coexistence structure dominated by Al12Mg17. In the processed coating, the upper part of the 1/2 radius zone containing Al12Mg17 exhibited a higher microhardness than the center zone. Moreover, the cold-sprayed Al coating provided more effective corrosion protection for the AZ91D substrate after FSSP.

Poor mechanical properties of copper (Cu) hinder its applications as structural materials. Developing bioinspired-laminated structure is among the most promising strategies for obtaining modern str...

Graphene has shown unique properties, introduced new challenges to light materials applicable in different areas. In addition to the polymer, has brought materials with marvelous properties either in mechanical, electrical, thermal, and conductivity. Different methods discovered to produce good nanocomposites, this review summarized those methods, also discussed the properties of graphene combined with different kinds of polymers. Furthermore, we studied the different factors affecting graphene reinforced polymer nanocomposites. In the end, the challenges and future underrating on graphene polymer nanocomposites were viewed.

With the continuous expansion of the application range of microelectromechanical systems, microdevice forming technology has achieved remarkable results. However, it is challenging to develop new microforming processes that are low cost, environmentally friendly, and highly flexible; the high-energy shock wave in a cavitation bubble’s collapse process is used as the loading force. Herein, a new process for the microbulging of the water-jet cavitation is proposed. A series of experiments involving the water-jet cavitation shock microbulging process for TA2 titanium foil is performed on an experimental system. The microforming feasibility of the water-jet cavitation is investigated by characterizing the shape of the formed part. Subsequently, the effects of the main parameters of the water-jet cavitation on the bulging profile, forming depth, surface roughness, and bulging thickness distribution of TA2 titanium foil are revealed. The results show that the plastic deformation increases nonlinearly with the incident pressure. When the incident pressure is 20 MPa, the maximum deformation exceeds 240 μm, and the thickness thinning ratio changes within 10%. The microbulging feasibility of water-jet cavitation is verified by this phenomenon.

Organic photovoltaic cells (OPVs) have great potential for driving indoor electronic devices for internet of things (IoTs). Under indoor illumination, the thick active layer can produce high photocurrent due to the large light-harvesting, whereas the trap states usually dominate the charge recombination in such thick-film devices and limit the largest possible photocurrent. Herein, we adopted a strategy of insulating polymer dilution to suppress the charge trapping states in the indoor organic photovoltaic (IOPV) devices with the different active layer thickness from 140 to 1000 nm. A diluting strategy with 5% insulating polystyrene effectively reduces the trap state density, delivering an excellent fill factor of around 67% and growth of short-circuit current density with increasing the thickness to 1-micron under 2700 K light-emitting diode tube. For the diluted ultra-thick blend, the reduced trap states suppress the exciton quenching at traps, accelerate the dissociation of intra-moiety polaron pairs and improve the transport properties, enabling more photogenerated carriers and low photocurrent loss in ultra-thick devices. This work provides an effective diluting strategy of decreasing trap state density for realizing ultra-thick IOPV devices with high performance and demonstrates the key role of charge trapping in IOPV performance.

The cavitation strengthening test of Aluminum lithium Alloy (8090Al–Li) was carried out with different pressure process parameters. The roughness, residual stress, and morphology of the treated samples were studied. A high dislocation density was formed in the cavitation area of the workpiece, which resulted in surfacing hardening. The cavitation effect occurred in the collapse area. It was beneficial for the process to be the right choice for the surface treatment of metal materials. The results confirmed that surface roughness, grain size, micro-strain, erosive effect, and micro-hardness of the alloy were significantly affected by different cavitation peening pressures. In this case, surface roughness increased as the impact pressure increased. Besides, the microcrystalline structure decreased in the cavitation treatment area. The study showed on how the impact of the different cavitation peening pressure could suppress the material surfaces, the compressive residual stress, attained the maximum values of −137 MPa to −162 MPa, which increased from 7.87 to 27.56%, as compared to the original sample. In contrast, the corresponding surface roughness average increased to 3.04 μm. Experimental observation shows that the cavitation collapse boundaries obtained by the proposed sample surface and metallographic images were highly complete and accurate.

Absorbable magnesium (Mg) materials are promising for medical implant applications. However, their corrosion rate and potential toxicity remain a challenge. Herein, a photo-cross-linked coating with suitable durability and unique surface-eroding behavior for enhancement of anticorrosion property and cytocompatibility of AZ31 Mg alloy was developed. The biodegradable allyl-functional polycarbonate, poly[(5-methyl-5-allyloxycarbonyl-1,3-propanediol carbonate)

Disposable medical protective clothing for 2019-nCoV mainly consists of stacked layers with nanopore films, polymer coated nonwoven fabrics and melt-blown nonwoven fabrics against anti-microbial and anti-liquid penetration. However, such structures lack moisture permeability and breathability leading to an uncomfortable, stuffy wearing experience. Here, we propose a novel medical protective clothing material with a superabsorbent layer to enhance moisture absorption. Poly(acrylic acid-co-acrylamide)/polyvinyl alcohol superabsorbent fibers (PAAAM/PVA fibers) were prepared via wet spinning. And the superabsorbent composite layer was stacked from PAAAM/PVA fibers, bamboo pulp fibers (BPF) and ethylene-propylene side by side fibers (ESF). The novel disposable medical protective composite fabric was obtained through gluing the superabsorbent layer to the inner surface of strong antistatic polypropylene nonwoven fabric. The resultant composite fabric possesses excellent absorption and retention capacity for sweat, up to 12.3 g/g and 63.8%, and a maximum hygroscopic rate of 1.04 g/h, higher than that of the conventional material (only 0.53 g/h). The moisture permeability of the novel material reached 12,638.5 g/(m2 d), which was 307.6% of the conventional material. The novel material can effectively reduce the humidity inside the protective clothing and significantly improve the comfort of medical staff.

Though MoS2 has been regarded a promising alternative to Pt for catalyzing hydrogen evolution reaction (HER), a transition from its natural poorly conductive 2H phase to metastable 1T phase is necessary, which often requires harsh experimental conditions. Herein, using a metal-organic framework (MOF) material (UiO-66) as sacrificing template, we proposed a facile solvothermal strategy to synthesize C/ZrO2@MoS2 nanocomposites whose morphology and phase could be effectively engineered simply by controlling reaction time. The optimized double yolk-shell structure allowed a stable hybridization of 1T- and 2H–MoS2, which exhibited improved HER activity (overpotential of 55 mV at 10 mA/cm2 and 58 mV/dec for Tafel slope) and considerable durability. Synergism of ZrO2–MoS2 heterointerface induced active sites and energetic favorable phase mixing of MoS2 is considered responsible for the sufficient electrocatalytic capability of our composite. Our work may offer new scientific insights into a cost-effective method for further enhancing the HER performance of MoS2-based nanohybrids.

Purpose Wear greatly influences the machine lifetime, performance and reliability and its quantification is very important. This paper aims to propose a modified bearing area curve method by combining the theory of the bearing area curve, and the relocation technique to calculate wear accurately and efficiently. Design/methodology/approach H13 steel was chosen as the material of wear pair, and the wear experiments were carried out at 50 N, 60 r/min for 20 min. The surface was measured before and after wear experiments. The relocation was made by comparing the mean lines (planes) of the unworn and worn surface profiles. The calculated results using the proposed method were compared with that of the surface profile method for a two-dimensional surface to validate its accuracy. The method was then applied for a three-dimensional (3D) wear analysis. Findings The worn surface shows clearly displacement compared to the unworn surface and implies the importance of including relocation in the bearing area curve method. The results from the proposed method are 98 per cent close to that from the surface profile method, indicating that the method is accurate for wear evaluation. Originality/value As no feature point or relocation mark is needed to calculate the relocation value using the proposed method, the method can be applied to mild to severe wear. Also, as the deviation of different scans does not affect the relocation calculation, and no matching and stitching is required, this method can be easily applied to a wide wear area and 3D surface wear analysis.

A key challenge for the fabrication of flexible electrochemical capacitors is to prepare robust electrode materials with excellent integration of high specific capacitances and superior mechanical properties. Aramid nanofibers (ANFs) are emerging candidates for constructing flexible electrode materials due to their superior mechanical properties. However, the present ANF based electrode materials are generally designed by mixing ANFs with electrochemically active components, which results in an unfavorable trade-off in mechanical and electrochemical properties. In this work, we reported flexible, mechanically strong, and free-standing supercapacitor electrodes based on polyaniline (PANI) nanostructure functionalized ANF films for the first time. The flexible PANI@ANF film electrodes achieved an efficient combination of mechanical and electrochemical performance in a single platform with a specific capacitance of 441.0 F g−1 at a current density of 1 A g−1 and a tensile strength of 233.3 MPa, respectively. This kind of free-standing electrode material may have great potential in the development of flexible energy-storage devices. Furthermore, we anticipate that this study may provide insight into the functionalization of aramid nanofiber-based materials for structural energy and power systems with high mechanical performance.

Polycarbosilane (PCS) fibers were cured by a process of alternating air and vacuum atmosphere periodically at thermal oxidation temperature. It was found that the oxygen diffusion in the micron PCS fibers could be observed and controlled by this novel curing process. The out surface layer of the cured fibers was rich in oxygen while the inner core had a lower status. Chemical structure analysis indicated that the groups of Si–H, Si–CH2–Si, and Si–CH3 in the out surface layer were oxidized into oxygen containing structures such as Si–OH, Si–O–Si and CO. Ascribe to the controlled oxygen diffusion, the oxidation degree of the inner core was much lower than the surface layer. The oxygen containing structures, Si–H bond reaction degree, molecular weight and ceramic yield of the cured PCS fibers increased with thermal oxidation temperature and alternating cycles. Theoretical calculation results demonstrated that the Si–H bonds reacted with oxygen was the main reason which made the PCS fiber increase weight. This modified process was a high effective surface layer oxidation curing method. Moreover, silicon carbide (SiC) or silicon nitride (Si3N4) ceramic fibers with skin-core or hollow structure also could be prepared from the surface cured PCS fibers with proper following process.

A lithium metal anode and high nickel ternary cathode are considered viable candidates for high energy density lithium metal batteries (LMBs). However, unstable electrode-electrolyte interfaces and structure degradation of high nickel ternary cathode materials lead to serious capacity decay, consequently hindering their practical applications in LMBs. Herein, we introduced N,O-bis(trimethylsilyl) trifluoro acetamide (BTA) as a multifunctional additive for removing trace water and hydrofluoric acid (HF) from the electrolyte and inhibiting corrosive HF from disrupting the electrode-electrolyte interface layers. Furthermore, the BTA additive containing multiple functional groups (C-F, Si-O, Si-N, and C═N) promotes the formation of LiF-rich, Si- and N-containing solid electrolyte interfacial films on a lithium metal anode and LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode surfaces, thereby improving the electrode-electrolytes interfacial stability and mitigating the capacity decay caused by structural degradation of the layered cathode. Using the BTA additive had tremendous benefits through modification of both anode and cathode surface layers. This was demonstrated using a Li||NMC811 metal battery with the BTA electrolyte, which exhibits remarkable cycling and rate performances (122.9 mA h g-1 at 10 C) and delivers a discharge capacity of 162 mA h g-1 after 100 cycles at 45 °C. Likewise, this study establishes a cost-effective approach of using a single additive to improve the electrochemical performance of LMBs.

This work focuses on the development of a system to control the formation of bone to complement developments that have enabled potent regeneration of bony tissue. Scaffolds were fabricated with chemically modified RNA encoding for bone morphogenetic protein-9 (cmBMP9) and capped with salicylic acid (SA)-containing polymer (SAPAE). The goal was to determine if SAPAE could inhibit the formation of bone in a pilot animal study since cmBMP9 has been demonstrated to be highly effective in regenerating bone in a rat calvarial defect model. The results indicated that cmBMP9 increased bone formation (30% increase in area covered compared to control) and that SAPAE trended toward reducing the bone formation. These results suggest SAPAE could be useful as a chemical agent in reducing unwanted bone formation in implants loaded with cmBMP9.

Boron nitride nanosheets (BNN) were prepared by molten hydroxide-assisted liquid exfoliation from hexagonal boron nitride powder with an effectively high yield, and then modified with hexachlorocyclotriphosphazene (HCCP) to obtain HCCP-BNN. The series of samples were applied to prepare flame-retardant cotton fabrics with the impregnation-drying method, and successful treatment was confirmed by scanning electron microscopy. The combustion performance of the as-prepared cotton fabrics was tested and evaluated. After coating with HCCP-BNN, the combustion rate of the fabric is reduced in vertical and horizontal combustion conditions and the limiting oxygen-index value of cotton fabric increases to 24.1, becoming less flammable than the blank cotton. The fibrous structure of the BNN and HCCP-BNN coated fabrics is relatively complete after combustion, which indicates that BNN have a certain protective effect on the fabric. The results demonstrate HCCP-BNN as an effective flame-retardant for cotton fabrics.

Purpose To construct and commission a double scattering (DS) proton beam model in TOPAS Monte Carlo (MC) code. Dose comparisons of MC calculations to the measured and treatment planning system (TPS) calculated dose were performed. Methods The TOPAS nozzle model was based on the manufacturer blueprints. Nozzle set-up and beam current modulations were calculated using room-specific calibration data. This model was implemented to reproduce pristine peaks, spread-out Bragg peaks (SOBP) and lateral profiles. A stair-shaped target plan in water phantom was calculated and compared to measured data to verify range compensator (RC) modeling. Results TOPAS calculated pristine peaks agreed well with measurements, with accuracies of 0.03 cm for range R90 and 0.05 cm for distal dose fall-off (DDF). The calculated SOBP range, modulation width and DDF differences between MC calculations and measurements were within 0.05 cm, 0.5 cm and 0.03 cm respectively. MC calculated lateral penumbra agreed well with measured data, with difference less than 0.05 cm. For RC calculation, TPS underestimated the additional depth dose tail due to the nuclear halo effect. Lateral doses by TPS were 10% lower than measurement outside the target, while maximum difference of MC calculation was within 2%. At deeper depths inside the target volume, TPS overestimated doses by up to 25% while TOPAS predicted the dose to within 5% of measurements. Conclusion We have successfully developed and commissioned a MC based DS nozzle model. The performance of dose accuracy by TOPAS was superior to TPS, especially for highly inhomogeneous compensator.

High-performance gas turbines and aircraft engines require high oxidation resistance MCrAlY bond coats. In this study, a novel heat treatment under low oxygen content was developed to prepare highly oxidation resistant MCrAlY bond coats. The results showed that after the heat treatment, metallic phases without as-deposited alumina film were exposed on the MCrAlY bond coat surface. The α-Al2O3 thermally grown oxide (TGO) with a larger grain size was formed on the heat-treated bond coat surface during isothermal oxidation. This larger α-Al2O3 TGO grain size significantly inhibited the TGO layer growth of MCrAlY bond coats by 2.7 times.

In the present work, phosphate-bonded porous silicon carbide (SiC) ceramics were prepared by using aluminum dihydrogen phosphate as binder. The morphologies, phase composition, microstructures, mechanical strength, porosity and bulk density of the porous ceramics were investigated. It was found that the aluminum dihygrogen phosphate binder bonding method was a novel and low cost process to prepare near net-shape and high strength porous SiC ceramics at low temperature. The bonding mechanism was A type and B type aluminum metaphosphate which formed from aluminum dihygrogen phosphate during heat treatment bonded the SiC particles together to form porous ceramics. With temperature increasing, the phase of B type gradually transformed into A type aluminum metaphosphate, and the transformation was completed at 900 °C. The A type aluminum metaphosphate began to decompose into AlPO4 and P2O5 when the sintered temperature higher than 908 °C. The flexural strength of the porous SiC ceramics reached the maximum at 900 °C and decreased sharply with temperature increasing. The decomposition of A type aluminum metaphosphate made the strength reduce. The bulk density increased with aluminum dihydrogen phosphate content and decreased with temperature, in contrast, the porosity decreased with increasing binder content and temperature.

Herein we report a facile two-step synthetic strategy for fabricating the ternary polystyrene/reduced graphene oxide/ceria (PS/RGO@CeO2) nanocomposite particles for the first time through the self-assembly of the RGO on the surface of PS microsphere (PS/RGO) and then the attachment of CeO2 nanoparticles (NPs) onto the as-prepared PS/RGO nanocomposite particles. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric analysis have been employed to characterize the morphology and composition of the as-prepared samples. The size and mass loading of resulting CeO2 NPs on the PS/RGO nanocomposite particles are easily tunable. Furthermore, the photocatalytic performance of as-prepared ternary nanocomposite particles towards the degradation of methylene blue is investigated. Notably, the PS/RGO@CeO2 nanocomposite particles have high photocatalytic activity due to the synergistic effect between the CeO2 NPs and RGO in such a unique structure, and moreover, they also exhibit high stability in a recyclable manner. Therefore, it can be expected that our ternary nanocomposite particles are an attractive photocatalyst candidate for various photocatalytic applications.

The interaction between De-NO and De-SO2 from flue gas in a pulsed corona discharge plasma (PCDP) reactor was studied experimentally. A mechanism and kinetic scheme of De-NO and De-SO2 inside the PCDP reactor has been proposed and verified by comparison of the simulated and experimental results. The dominant radicals and elementary reactions are confirmed through sensitivity analysis. It has been found that there is significant interaction between the De-NO and De-SO2 processes in a PCDP reactor, and that the De-NO reactions prevail over the De-SO2 ones. The interaction consists of competitive reactions between NO and SO2 involving oxidative radicals, as well as interaction reactions between NO, SO2 and their derivatives. Through sensitivity analysis it has been found that the most effective elemental reaction to De-NO is NO + HO2 OH + NO2 and that the most helpful radical is HO2. The most effective reaction for De-SO2 is SO2 + O SO3 and the most helpful radical is atomic O. The study reveals the interaction mechanism between De-NO and De-SO2 in PCDP and provides a theoretical basis to improve the performance of simultaneous NO and SO2 abatement in a PCDP reactor.

This paper developed a novel method and relevant mechanical configurations to enhance strain sensitivity and realize temperature compensation simultaneously for fiber Bragg grating (FBG)-based strain sensor. The theoretical strain amplification model and temperature compensation model of the designed method and the manufactured sensor specimen were derived based on the theory of elastic mechanics and the methodology of matrices. The established theoretical sensing models were validated through finite element method (FEM) and experimental tests. The theoretical, FEM, and experimental results show good consistency. The overall sensitivities of the two FBGs in the developed sensor achieve 7.72 pm/μe and −2.94 pm/μe respectively, which are respectively 6.43 and −2.45 times of the strain sensitivity of a bare fiber Bragg grating strain sensor. The decoupling of strain and temperature was implemented theoretically and verified experimentally. The developed sensor in this paper can be used for long-term small-amplitude micro-strain monitoring in varying temperature environments for vital mechanical equipment.

To study the evolutionary characteristics of mesostructural damage to saturated limestone under different loading and unloading paths, three types of loading and unloading tests involving three different loading rates and initial peak stresses were performed. Nuclear magnetic resonance technology and scanning electron microscopy were used to investigate the evolutionary characteristics of pore water during the loading and unloading of the limestone. The results indicated that, with an increase in the initial peak stress, the rock viscoplasticity gradually decreased, and the variation of pore radius and the reduction of bound water decreased. With an increasing loading rate, the mesostructure evolution law under disturbance-increasing amplitude (DIA) cycling was opposite to those under increasing amplitude (IA) and repeated-increasing amplitude (RIA) cycling. With the increasing loading stress level, the porosity decreased and then increased. Under increasing amplitude cycling, a larger initial porosity resulted in higher pore compaction and expansion limits. Reducing the initial peak stress inhibited the pore expansion, whereas it had the opposite effect under RIA and DIA cycling. During loading and unloading, bound water exists in pores of organic matter and mesopores, and free water exists in macropores of intergranular and transgranular fractures. These changes indicate certain laws under different loading and unloading paths. The results of this study indicate that the mesostructure characteristics of rock depend on the loading and unloading paths.

To study the acoustic emission evolution characteristics of saturated limestone under different loading and unloading paths, three cyclic loading and unloading tests were conducted with different loading rates and initial cyclic peak stresses, and acoustic emission monitoring was performed simultaneously. The results indicate that, during loading and unloading, the intermediate-frequency signals of saturated rock exhibit a variation trend of sparse–dense–sparse signals, whereas the low-frequency signals are continuously and massively produced. With the increase in the loading rate, the development trends of cumulative hits and energy become closer, and the development form of ringing count changes from N-type to U-type and then to N-type. The slight increase period and attenuation period are extended, whereas the intense growth period and postpeak calm period are shortened. With an increase in the initial cyclic peak stress, the change in cumulative energy is more obvious than that in cumulative hits near the rock failure. The development form of the ringing count changes from U-type to W-type and then to N-type, and each period is first shortened and then extended. With the increase in loading rate, the increase in the slow-change period tends to change from gradually increasing to increasing and then decreasing. By contrast, the increase in the step tends to change to a gradual increase. With the increase in the initial cyclic peak stress, the duration of and increase in the energy in the step and the slow-change period tend to decrease and then increase.

The performance of gearbox vibration monitoring techniques may degrade due to the signal distortion and attenuation which is usually caused by the complicated transmission path. The fiber Bragg grating sensing technique has attracting characteristics such as the small size, multiple measurement points on one fiber and resistance to oil corrosion. Therefore, this paper proposes a new approach for online monitoring of gearboxes based on fiber Bragg grating based strain sensors, in which the fiber Bragg grating sensors can be mounted closely to the meshing position of gear teeth. In this study, the working principle of the fiber Bragg grating and the configuration of the test rig is firstly presented. Then, the tooth root dynamic strain signals measured by fiber Bragg gratings under the healthy and gear pitting conditions were presented and compared with the finite element simulations. The comparison between the measured and simulated signals agrees well, which validates the feasibility of the employment of fiber Bragg gratings for the online monitoring of gearboxes. Furthermore, a novel diagnostic algorithm based on dynamic time warping is proposed to process the measured signals using fiber Bragg grating based strain sensors. The results show the proposed algorithm is able to diagnose the healthy and gear pitting conditions without the need of the pre-measured baselines.

Dry-type hollow reactor is widely used in power system, its operating environment is bad, the annual sun and rain also accelerate the aging of its insulation, it is easy to cause the dry reactor inter-turn insulation damage and burn down. At present, the main methods of live detection of dry reactor are infrared thermal imaging technology. DC resistance and insulation resistance are required in blackout test. These tests can not detect the inter-turn insulation of dry reactor. In this paper, the magnetic field and impedance characteristics of the interturn insulation damage of dry reactor are studied. The magnetic field changes and impedance characteristics of dry reactor are simulated by using ANSYS analysis software when the interturn magnetic field occurs in the end and middle of the reactor, respectively. A fault simulation platform for dry reactor is established, and a new method for interturn insulation detection is proposed.

In this work, we have developed a green, simple and fast one-pot microwave-assisted strategy for synthesis of nitrogen and sulfur co-doped fluorescent carbon dots (CDs) using scallion (SL) as the carbon source. Optical properties of the SL-CDs have been measured by UV-visible and fluorescent spectroscopy. The morphology of the prepared SL-CDs has been performed by transmission electron microscopy (TEM). Surface functionality and elemental composition of SL-CDs was analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) spectra. The photoluminescent (PL) quantum yield of the obtained scallion carbon dots (SL-CDs) can reach as high as 18.6%. We further demonstrated that the SL-CDs can be used as fluorescent probes for detection of Cd2+ ions with a high sensitivity and an excellent selectivity. Linear relationships between the variation of the luminescent intensity of the SL-CDs before and after exposing the Cd2+ ions versus the concentration of Cd2+ ions in the range of 0.1–3.0 μM and 5.0–30.0 μM. The detection limit of Cd2+ ions can reach 15.0 nM. Moreover, the as-prepared SL-CDs exhibit negligible or extremely low cytotoxicity, which makes them be able to be used as fluorescent probes for living cell imaging. Overall, the prepared SL-CDs have promising applications in sensing of Cd2+ ions and in vivo or in vitro bioimaging.

MCrAlY bond coats with high oxidation resistance are essentially important for improving the life-time of thermal barrier coatings (TBCs). In this study, highly oxidation resistant MCrAlY bond coats were prepared by a cost-effective approach involving air plasma spraying (APS) followed by a controlled atmosphere heat treatment (a diffusion treatment performed in a furnace filled with Ar). The results confirmed that a pure α-Al2O3 thermally grown oxide (TGO) was successfully formed on the surface of the heat-treated APS bond coats during isothermal oxidation. The oxidation resistance of the resulting APS bond coats was as high as that of low-pressure plasma sprayed bond coats, which are very expensive. The high oxidation resistance of the APS bond coats fabricated in this study can be attributed to the structural changes of the interface between the splats inside the coating. During the controlled atmosphere heat treatment, the lamellar oxides present between the splats within the as-sprayed APS bond coats converted into isolated oxide particles, and the metal elements could diffuse freely within the coating after the healing of the interface between the lamellar splats. The effect of the changes in the interfacial microstructure of the bond coats on the growth of the TGO was discussed.

Controllable synthesis of mesoporous photocatalysts is of great interest for the photocatalytic remediation of organic pollutants from wastewater by sunlight. In this work, we have developed a new photocatalyst with nitrogen-doped carbon (NC) and mesoporous TiO2 (mTiO2) interpenetrating hetero-structure by a sol–gel process combined with an in situ carbonization strategy. The synthesized nanospheres possess a uniform particle size (~ 60 nm), high surface area (~ 108 m2/g), and large pore diameter (~ 2.1 nm). Most importantly, the nanospheres consist of ultrasmall TiO2 nanocrystals (~ 8.2 nm), which are uniformly coated by a thin layer of N-doped carbon. Significantly, the resultant NC/mTiO2 composite nanospheres exhibit a broad light absorption in the range of 200–2000 nm (entire wavelength). When serving as a photocatalyst for organic pollutants degradation, high performance was obtained. Accordingly, the resultant NC/mTiO2 composite nanospheres performed in an excellent manner in the photodegradation of methyl orange, and the total removal efficiency was up to 97.7%, much better than that of commercial P25 (19.8%). Furthermore, the nanocomposite also effectively photodegraded other organic pollutants such as methylene blue (dyestuff) and phenol, respectively. Therefore, the resultant NC/mTiO2 nanocomposites have potential applications in environmental cleanup.

In contrast to AI hardware, neuromorphic hardware is based on neuroscience, wherein constructing both spiking neurons and their dense and complex networks is essential to obtain intelligent abilities. However, the integration density of present neuromorphic devices is much less than that of human brains. In this report, we present molecular neuromorphic devices, composed of a dynamic and extremely dense network of single-walled carbon nanotubes (SWNTs) complexed with polyoxometalate (POM). We show experimentally that the SWNT/POM network generates spontaneous spikes and noise. We propose electron-cascading models of the network consisting of heterogeneous molecular junctions that yields results in good agreement with the experimental results. Rudimentary learning ability of the network is illustrated by introducing reservoir computing, which utilises spiking dynamics and a certain degree of network complexity. These results indicate the possibility that complex functional networks can be constructed using molecular devices, and contribute to the development of neuromorphic devices., Neuromorphic hardware is based on principles of neuroscience, and has the potential to provide higher-level brain functions. Here, the authors develop a neuromorphic network device, constructed from single-walled carbon nanotubes and polyoxometalate, that mimics nerve impulse generation.

In this study, the mechanisms responsible for enhancing the adhesion strength of thermally sprayed metallic coatings subjected to vacuum heat treatment were investigated using atmospheric plasma sprayed (APS) CoNiCrAlY coatings as an example. The formation of metallurgical bonding between the coating and the substrate, which determined the increase in the adhesion strength of the coatings, was studied by analyzing the effect of morphological changes of the oxide film in the coating. The results showed that during the vacuum heat treatment process, the oxide film formed during the coating deposition gradually broke down and subsequently shrank into round-shaped oxide inclusions. After vacuum heat treatment, the adhesion strength of the coating improved significantly. The increase in the adhesion strength was caused by the formation of metallurgical bonding between the coating and the substrate. However, the prerequisite for the formation of metallurgical bonding was that the oxide film had to break during the vacuum heat treatment process. A thermodynamic 2D model based on the thermal grooving theory was proposed to explore the essential conditions for the breaking and shrinking of the oxide film. The results predicted by the 2D model and the experimental results were in good agreement with each other and indicated that at a given temperature, the breaking of the oxide film is directly related to its thickness.

Molten plastics are characterised with high viscosity and low thermal conductivity. Applying falling film pyrolysis reactor to deal with waste plastics can not only improve heat transfer efficiency, but also solve the flow problem. In this work, the pyrolysis process of molten polypropylene (PP) in a vertical falling film reactor is experimentally studied, and the influence of heating temperature on pyrolysis products is discussed. It has been found that with the temperature increases from 550 °C to 625 °C, the yield of pyrolysis oil decreases from 74.4 wt% (± 2.2 wt%) to 53.5 wt% (± 1.3 wt%). The major compositions of the pyrolysis oil are C 9 , C 12 and C 18 , and β-scission reactions are predominant. The content of the light fraction C 6 –C 12 of pyrolysis oil is 69.7 wt%. Compared with other pyrolysis reactors, the yield of oil from vertical falling film pyrolysis reactor is slightly higher than that from tubular reactor, equal to that from rotary kiln reactor, and slightly lower than that in medium fluidised-bed reactor.

Investigations of protein folding, unfolding and stability are critical for the understanding of the molecular basis of biological structure and function. We describe here a microfluidic approach to probe the unfolding of unlabelled protein molecules in microliter volumes. We achieve this objective through the use of a microfluidic platform, which allows the changes in molecular diffusivity upon folding and unfolding to be detected directly. We illustrate this approach by monitoring the unfolding of bovine serum albumin in solution as a function of pH. These results show the viability of probing protein stability on chip in small volumes.

To investigate the relevancy of infrared thermal imaging and tumors inside human body, the finite element model of human thigh with four-layers, including bone, muscle, fat and skin layers, is established in this paper. Based on the characteristic that temperature varies along radial direction inside the body, the heat generation rate of blood perfusion as a function of polar radius in each layer is given. By this method the nonlinear problem of temperature-dependence of the heat generation rate of blood perfusion in finite element analysis is solved. Then the temperature distributions caused by the inside tumor with different sizes and at different depths are numerically calculated by finite element analysis. It can be concluded that in the given range of tumor diameters a smaller tumor yields larger temperature increases inside the body, higher peak temperature and narrower FWHM(Full Width at Half Maximum) of the temperature distribution on the skin surface. It is also shown that with specific diameter, tumors located deeper yield higher peak temperature inside the body, and lower peak temperature and wider FWHM on the skin surface.

Achieving an efficient and inexpensive bactericidal effect is a key point for the design of antibacterial agent. Recent advances have proved molybdenum disulfide (MoS2) as a promising platform for antimicrobial applications, while the combination of metal nanoparticle would promote the antibacterial efficiency. Nevertheless, the dispersivity, cheapness and safety of metal nanoparticle loaded on MoS2 raised some concerns. In this paper, we successfully realized a uniform decoration of copper nanoparticles (CuNPs) on surface of MoS2 nanosheets, and the size of CuNPs could be controlled below 5 nm. Under 5 min irradiation of 660 nm visible light, the synthesized CuNPs/MoS2 composite demonstrated superior antibacterial performances (almost 100% bacterial killed) towards both Gram-negative E. coli and Gram-positive S. aureus over the single component (Cu or MoS2), while the bactericidal effect could last for at least 6 h. The synergism of photodynamic generated hydroxyl radical (·OH), oxidative stress without reactive oxygen species production and the release of Cu ions was considered as the mechanism for the antibacterial properties of CuNPs/MoS2. Our findings provided new insights into the development of two-dimensional antibacterial nanomaterials of high cost performance.

Organic solar cells have received widespread attention with the development of indoor light harvesters. Due to the narrow emission spectra and weak light intensity of indoor emissions, the short-circuit current of indoor devices is largely restricted, and there would be an additional voltage loss around 0.15 V from the light intensity difference. However, most state-of-the-art cells cannot be adopted as indoor photovoltaics directly, because their small optical bandgaps lead to open-circuit voltage (VOC) values in the range of ~0.6 V in dim-lighting, which is difficult to drive most of internet of things. Herein, we revaluate the photovoltaic performance under indoor illuminances by combining a wide-gap polymer PBDB-T with various electron-accepting materials. The PBDB-T: BTA3 cell achieves an excellent efficiency higher than 25% under a 1000 lux 2700K LED illumination. The VOC value of such a device can still maintain close to 1 V under indoor cases. We then compare the underlying mechanism of the PBDB-T-based bulk heterojunctions (BHJs) with multiple techniques, and the results indicate the unchanged advantage of high VOC helps the BTA3-based cell shows the best indoor device performance when the light source is switched from AM1.5G to low illumination. This work revaluates the selection of state-of-the-art indoor light harvesters, and demonstrate an excellent optimal efficiency of the PBDB-T:BTA3 indoor cell up to 25.6%, with a desirable VOC of 0.99 V.

The clinical applications of magnesium (Mg) alloys remain a challenge due to their corrosion rate and toxicity problems. Herein, we report a biodegradable polyacrylate copolymer coating for enhancement of Mg alloy's anticorrosion performance and biocompatibility. Specifically, the biodegradable polyacrylate copolymer was first synthesized through the free-radical ring-opening copolymerization of 2-methylene-1,3-dioxepane (MDO), vinyl acetate (VAc), 7-(2-methacryloyloxyethoxy)-4-methylcoumarin (CMA), and dopamine methacrylamide (DMA). The poly(MDO-co-VAc-co-CMA-co-DMA) (PMVCD) coating was then applied on the surface of Mg alloy using electrophoretic deposition (EPD) and crosslinked under UV irradiation. The photo-crosslinking ability and biodegradability of PMVCD coating was provided by the CMA and MDO moieties, respectively. Potentiodynamic polarization, electrochemical impedance spectroscopy and in vitro degradation test demonstrated that the corrosion rate of PMVCD-coated Mg alloy was significantly decreased. Additionally, the enhanced cytocompatibility of PMVCD-coated Mg alloy was confirmed by in vitro cytotoxicity test.

This study aims to investigate the influence of friction stir spot processing (FSSP) on the microstructure, microhardness, and adhesion strength of the cold-sprayed Al coatings on Ti substrates. A sound and dense coating is obtained at 2400 rpm. The pores and inter-particle interfaces completely disappear, and the equiaxed grains with low dislocation density are observed in the stir zone (SZ) after FSSP. The varying grain sizes and dislocation densities are found in different positions of the SZ under different rotation speeds. However, the Taylor factors are almost unchanged before and after FSSP. Compared with the as-deposited coating, the microhardness dramatically increases in the SZ after FSSP. Furthermore, when the dislocation density and crystallographic orientation are similar in different positions of the SZ, the microhardness variations can be interpreted by the Hall-Petch relationship, and the kH and H0 of the Hall–Petch relationship for the SZ of the FSSPed Al coating are obtained. The influence of the dislocation density and crystallographic orientation on the microhardness in the SZ is also discussed. Moreover, the TiAl3 layer generates at the interface between the coating and substrate after FSSP. The continuity of the TiAl3 layer is strongly dependent on the rotation speeds during FSSP, which further affects the coating adhesion strength.