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Polyacrylonitrile (PAN) based carbon fibers possess high performance and wide applications. Preoxidation, as one of the crucial steps in the preparation of carbon fibers, refers to the process in w...

Magnetic targeted drug delivery systems can improve drug utilization and reduce drug side effects. There are still many difficulties to be overcome in clinical practice. The main problems include providing large enough magnetic capture particles to concentrate drug-loaded magnetic micro-nanoparticles (MNPs) to the lesion site. The existing research focuses on the development of targeted carriers, and the magnet device has not formed a mature research system. Based on the recent development of magnet devices in recent years, this paper proposes the research direction of potential magnet devices. From the dynamic behavior of the particles under the magnetic field, the magnetic system and the mathematical model design direction of the optimized magnet are developed. This article describes the obstacles encountered in drug targeting in the study of magnet devices and summarizes the potential development of future magnet devices.

Cobalt-based superalloys have good service performance in environments where nickel-based superalloys cannot work. A number of the studies focused on mechanical properties, microstructure evolution and hot deformation characteristics, but studies of meta-dynamic recrystallization (MDRX) behavior remain lacking. The MDRX behavior of GH5188 superalloy was investigated using two-stage hot compression tests. The kinetic model and grain size model were built to better describe the MDRX process. The good agreement between the predicted values and experimental values was verified. The effects of holding time, temperature, strain rate and intervals time on MDRX microstructure evolution were analyzed and discussed. The results show that by descending order of correlation was: intervals time, holding time, temperature and strain rate. The MDRX fraction and grain size increase with the increase of holding time, temperature, strain rate and intervals time. At low temperatures, MDRX grains grew up in the form of bowed grain boundaries. At high temperatures, the growth of MDRX grains was often accompanied by the generation of twinning bands. Twins were formed in the process of grain growth.

Among various nanomaterials used for food packaging, zinc oxide (ZnO) nanoparticles are one of the best choices due to their high antimicrobial property. However, for biodegradable materials like poly(butylene adipate-co-terephthalate) (PBAT), biodegradability can be limited by the antibacterial function. Thus, in the present study, reinforced PBAT films with different weight percentages (1, 3, and 5 wt%) of ZnO nanoparticles were prepared by the casting process to investigate the effects of ZnO on the thermostability, mechanical, and antimicrobial properties of the PBAT film. The results showed that the small amount of ZnO (1 wt%) reduced the decomposition temperature of the PBAT film by nearly 50 °C, and the thermal stability was significantly decreased with the increasing ZnO content. Melt flow index comparison showed that the ZnO nanoparticles accelerated the room temperature degradation rate of PBAT films. In addition, due to the degradation effect of ZnO nanoparticles, the mechanical properties such as the total percentage of elongation (at break), the tensile strength, and yield strength decreased with the addition of ZnO nanoparticles. The antibacterial test showed that PBAT + 1 wt% ZnO films could achieve high antibacterial activity (R = 6.8) against Escherichia coli. This study is important for controlling the degradation period of biodegradable materials.

In this study, an Si nanowire (SiNW) array was prepared on a single-crystal Si wafer by a facile Ag-assisted wet-chemical etching route, followed by deposition of ultrathin Pt nanoparticles for enhancing the photoelectrochemical (PEC) performance. It was demonstrated that the PEC performance of SiNWs was enhanced significantly after Pt modification. A higher photocurrent density of − 12 mA cm−2 was achieved in Pt/SiNWs at − 0.845V versus a reversible hydrogen electrode, which was six times greater than that of bare SiNWs. The mechanism for the enhanced PEC performance was analyzed by combining the electrochemical impedance spectra and Mott–Schottky plots. As a result, the mechanism was attributed to the improved charge transfer ability at the solid electrode/electrolyte interfaces.

Wide-angle X-ray scattering (WAXS) is routinely used to characterize the ordered structure in materials. The measured angles are generally calibrated by using standard samples with several diffract...

It has been proved that Bermuda grass root is an effective material to improve the mechanical properties of soil, but the effect of the dry–wet cycles should be considered when this material is applied to the reservoir slopes. In this study, specimens with different root content were subjected to dry–wet cycles, then the unconfined compressive test was carried out to study the effect of dry–wet cyclic numbers and root content on the strength of the root-soil composites. Through the unconsolidated undrained triaxial compression test, the effect of the dry–wet cyclic numbers and root content on the shear strength parameters of the root-soil composites was investigated. The results illustrated that the mechanical properties of the root-soil composites decreased with the increase of dry–wet cyclic numbers, but increased with the increase of root content. After the root content exceeded an optimum value, the unconfined compressive strength and shear strength parameters of the root-soil composites decreased significantly. The optimum root content for achieving the maximum shear strength and unconfined compressive strength was 0.15% and 0.20%, respectively. The results in this study could provide guidance and reference for the design and construction of hydropower stations.

Dissipative particle dynamics (DPD) simulations was adopted to investigate the modification of polyvinylidene fluoride (PVDF) membrane by adding zwitterionic polymer brush poly(sulfobetaine methacrylate)- tetraethyl orthosilicate (PSBMA-TEOS) grafted silicon nanoparticles (SNPs) to the casting solution. The effects of polymer concentration and grafting architecture (PSBMA length and SNPs grafting ratio) on membrane morphology are discussed. When the polymer concentration reaches 40%, part of the SNPs is embedded in the membrane; the optimal polymer concentration is around 25–30%. In the SNPs system with the grafting ratio of 1, some SNPs are eluted into solution during phase separation. Compared with different grafting architectures, M8-5, M10-5 and M12-5 system (Mx-y, where x represents the length of the zwitterionic polymer brush and y represents the grafting ratio of the silica nanoparticles) exhibited stable membrane morphologies. This work can provide guidance for the design and modification of organic-inorganic composite membrane and help understand the distribution of modified materials on the membrane surface.

Electret filters display enhanced ability for particle collection due to its additional electrostatic attraction. However, their efficiency degradation during particle loading remains to be solved. Herein, the loading characteristics of electret filters with neutral particles is investigated via immersed boundary-lattice Boltzmann method (IB-LBM). The specific charge distribution on the electret fibers, and the fiber charge decay due to gas neutralization and particle conduction are incorporated in the model. Results verify that the distribution of bipolar charges randomly on fibers with equivalent area is reasonable. The efficiency degradation depends on the proportion of electrostatic collection in the whole particle filtration process, and the attenuation of electrostatic intensity in the electret filter. With the same loaded mass, carbon particles with higher conductivity cause more charge decay and efficiency degradation than NaCl and Al2O3 particles. The fiber charge is mainly lost through conduction, and gas neutralization becomes important only for high-resistivity materials.

The resulting supported catalytic materials were probed for a series of Pty/TixCe(1-x)O2 (y = 0.005, 0.05, 0.5, 1, 5; x = 0.98, 0.9, 0.7, 0.5, 0.3, 0.02) supports primed by the sol-gel method. By u...

Although silk fabric has a good performance in softness, smoothness, permeability, and comfort, its poor UV resistance and easy yellowing seriously influence its appearance and further application....

PEM-based electrolytic air dehumidification is innovative in dehumidification that requires high precision and small space due to its high efficiency, compactness, and cleanness. However, the system dehumidification performance and durability are limited by using commercial Anatase-IrO2 catalysts. In this study, two types of structurally modified OER catalyst materials, ATO-IrO2 and ND-MnO2-IrO2, are developed to improve the performance of the system. System experiments showed that, compared to the commercial catalysts, the use of ATO-IrO2 and ND-MnO2-IrO2 as the anode catalyst can improve the dehumidification performance by 45% and 20%, respectively. Furthermore, in 50-h accelerated aging tests, the attenuation rates of the ATO-IrO2 and ND-MnO2-IrO2 systems are 3% and 8% respectively, which are far lower than the 35% attenuation of commercial catalyst. The results indicate that, as catalysts with a classic core-shell structure, ATO-IrO2 and ND-MnO2-IrO2 still have a significant impact on improving the performance of the electrolytic dehumidification systems.

Two tetra-nuclear YbIII-incorporated selenotungstate clusters, Keggin (C2H8N)6Na14[Yb4Se6W44O160(H2O)12]·40H2O (1) and Wells–Dawson (C2H8N)4Na14[Yb4Se6W45O159(OH)6(H2O)11]·38H2O (2), have been isolated through a pH-controlled assembly, which exhibit the first YbIII-containing polyoxotungstates with selenium heteroatoms. Their assemblies rely on the structure-directing effects of SeO32− anion templates to give rise to available Se-containing Keggin-/Wells–Dawson-type motifs. Both compounds were characterized by single-crystal X-ray diffraction, IR spectroscopy, power X-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) as well as electrospray ionization mass spectrometry (ESI-MS). Furthermore, systematic magnetic studies revealed that 1 exhibits field-induced single-molecule magnetic behavior with a pre-exponential factor of τ0 = 6.60(7) × 10−8 s and a relaxation energy barrier of ΔE/kB = 39.44(2) K, while 2 only displays antiferromagnetic interactions between the ytterbium centers.

Desalination by freezing/thawing method was a very important method to obtain fresh water from sea water. In this work, desalination by freezing/thawing method was conducted with initial sodium chloride of 3.5 wt% in consideration of stirring speed, freezing time and subcooling. The subcooling ranged from 1.2 K to 4 K. The optimum conditions for desalination in this work were stirring speed of 200 r·min−1, freezing time of 120 min, and subcooling of 3 K. The results also showed that sodium chloride cannot be effectively removed by once freezing/thawing process. The maximum removal efficiency of sodium chloride was 64.3%. Two major reasons resulting in the impurity of obtained melted water by freezing/thawing method were proposed. The first reason was the inevitable adhesion of salt solution to the surface of ice, which could be removed easily by distilled water flushing. The second reason was that salt solution was heterogeneously wrapped in the accumulated ice, which was difficult to be removed by distilled water flushing. The liquid flushing method was proposed to verify the conjecture, and the results were in accordance with the two reasons mentioned above. Additional method, such as multiple flushing liquid method, was suggested to be used during the freezing/thawing process for effectively removing sodium chloride, and obtaining fresh water.

The changes in fractal structure during high-temperature (1200°C) carbonisation of a Chinese non-caking coal were studied in situ by synchrotron radiation small-angle X-ray scattering (SAXS). The r...

Dehumidifier with Polymer electrolyte membrane (PEM) is suitable for high-accuracy, limited-space humidity control in refrigerators. This study experimentally investigated the performance of PEM-based dehumidifier under the temperature range of -10~10°C. Empirical equations of PEM water content at refrigerator temperatures were developed. Results showed that although the low-temperature performance of electrolytic dehumidifier is not as good as that of room temperature, the efficiency (~1.3 × 10−2 g·J−1·m−2) is still competitive to desiccant or electrochemical methods. The dehumidifier has a starting voltage, and the voltage is higher at lower air temperatures (i.e. 1.3V for 26.1°C and 2.3 V for -3.9°C). During dehumidification, the operating current first increases significantly and then drops as the applied voltage increases, leading to a first increase and then steady dehumidification rate. The peak of current occurs at a smaller voltage as the air temperature decreases, i.e. 1.8V for 0°C and 2.5V for 26°C. Furthermore, the dehumidification rate increases as the air temperature and flow rate increases, while the changing rate with operating conditions was lower at sub-zero temperatures. Dehumidification has little effect on the oxygen concentration or temperature increment of the supply air. Characterizations also indicated that there was no obvious physical change on the PEM surface after operating at low temperatures. However, there exists a starting temperature for the dehumidifier, i.e. -9.5°C for the 3V applied voltage, which is due to the possible icing and swelling problem within the membrane. This study provided a new method, and proved its feasibility for dehumidifying at refrigerator temperatures.

With the increase of China's grain production, the use of pesticides is gradually increasing. Traditional pesticide detection takes a long time and requires expensive experimental instruments, which is not conducive to the rapid and accurate detection of pesticide residues in the field. To solve this problem, this paper proposes a visual detection method of pesticide residues based on multi-layer microfluidic paper chips. The internal channel structure of paper chip is designed from the perspective of efficient mixing. Through the simulation of the mixed effect of three kinds of staggered channel structures, which are arc type, triangle type, and ladder type, the "ladder-type h-0.3, s-2.6" is selected as the best-staggered structure, and the mixing strength is 0.91534. The best simulation structure was tested by a colored reagent, and the image processing of 15 test results was carried out with MATLAB. The average mixing strength was 0.84, and the and the standard deviation was 0.022. The visual detection experiment of acetamiprid and profenofos in cabbage samples was carried out by using the device，The detection range of acetamiprid was 4~72 μg/kg, and the detection range of profenofos was 3~54 μg/kg . The recovery of acetamiprid was 75%~85%, and the recovery of profenofos was 80%~90%. The detection range and recovery rate indicate that the device has high repeatability and accuracy in the actual sample detection

This paper aims to examine deposition reduction performance of different types of dust on solar PV cells by the self-cleaning coatings. Four types of dust were obtained from the Powder Technology Inc. USA (Dust A), the Henan province in the central China (Dust B), the Guangzhou city in the Southern China (Dust C) and the sand in the construction site (Dust D), respectively. The micro and macro patterns of particles, the particle deposition density, the transmittance and the output power reduction of PV system after dust deposition were investigated carefully. It was found that the particle deposition density on the solar cell covering glass is obviously decreased by the coating. The deposition density of the sand particles is 36.77% of that on the uncoated glass case, which is the minimum among the four types of dust because of the high Young’s modulus and low surface energy of the sand. The self-cleaning coating has the best power efficiency improvement performance for the dust C (about 24.35%), followed by the dust B (about 19.83%) and dust D (about 18.21%). The dust A has the minimum efficiency improvement (about 12.47%) by the super-hydrophobic coating.

The unexpected resistance reduction effect of double-trench SiC MOSFETs under repetitive avalanche stress is investigated in this work. After enduring repetitive avalanche stress, the ON-state drain-source resistance (Rdson) of the device decreases. With the help of TCAD simulations, the dominant mechanism is proved to be the injection of positive charges into the gate trench bottom oxide, which is almost irreversible under zero-voltage bias condition at room temperature. For the injected positive charges attract extra electrons just beneath the gate trench bottom, where the carriers pass through under ON state, the resistivity there is reduced, improving the conduction capability of the device. Moreover, an optimization method is proposed. Since the impact ionization rate (I.I.) and the vertical oxide electric field (E⊥) along the gate trench bottom oxide interface contribute to the injection of positive charges, it is recommended to make the bottom oxide thicker to suppress this effect.

Electrolytic air dehumidification (vapor electrolysers) based on proton-exchange membrane (PEM) is competitive to conventional dehumidifiers, but serious degradation has been found in long-running applications. This study conducted the durability test of electrolytic dehumidifier, under continuous operation for more than 250 h. Changes in current and dehumidification rate were analyzed and compared to those for fuel cells and water electrolysers. Physicochemical and electrochemical changes of the materials before and after the test were investigated. Results show that higher applied potential or higher air humidity corresponds to a larger dehumidification amount, while performance attenuates more quickly over time. When the applied potential increased from 2 V to 4 V, the degradation rate increases from 23% to 67% at 90% air humidity. Simultaneously, the internal resistance of PEM element increased from 0.419 to 1.45 Ω and the reaction resistance changed from 1.13 to 2.17 Ω, indicating by in-situ and ex-situ EIS. By characterization analysis, it indicated that the corrosion of the anode-side catalyst IrO2 is the main reason for the long-term attenuation. The grain size of almost all IrO2 faces reduced after 250 h dehumidification, and the content of active metal of the catalyst lost by 54.3%. The dissolution rate of IrO2 also increases with increasing applied potential. Besides, there is almost no physical or chemical damage on PEM or cathode catalyst before and after the durability test. This research clarifies the micro-scale changes of the materials during long-term operation, and discloses the degradation mechanism of PEM-based electrolytic dehumidifiers.

The medium-consistency (MC) pump is the key unit in modern pulp and paper industry, especially in medium-consistency bleaching plant. Use of MC pump improves the efficiency of bleaching sequences and reduces the pollution load of bleaching effluents. In this work, the component of MC pump, e. g. turbulence generators with three typical structures were studied to evaluate the effects of turbulence generator structure on the performance of MC pump. An automatic control system was built to control operation condition and to collect data online. Head and efficiency were calculated to evaluate the differences among three turbulence generators. The results showed that the linear-type, twist-type and screw-type turbulence generators exhibited similar performance (pump head and efficiency) of MC pump at high rotation speed (2000 rpm to 2900 rpm) compared to the well-known performance of MC pump at rotation speed lower than 2000 rpm which are significant different for the three turbulence generators.

As an important excitation source of gear dynamic problems, the time-varying friction of tooth surface is closely related to its topography. Considering the friction characteristics of tooth surface is of great significance to improve the calculation accuracy of gear dynamic characteristics. In order to solve the problem that the variation of tooth friction coefficient was simplified too much in the previous gear dynamics research, the time-varying tooth friction coefficient is obtained by fitting the results of twin-disc test in this research. To investigate the influence of tooth surface topography on the friction and dynamic characteristics of spur gears, the relationship between surface topography and friction coefficient under line contact condition is studied using twin-disc tester and analyzed by 3D topography parameters in ISO 25178. The time-varying friction coefficients of spur gears with different tooth surface topographies during meshing are fitted with the experimental results. The influence of time-varying friction coefficient caused by the tooth surface topography on the dynamic characteristics of spur gears under different operating conditions is examined by substituting the fitting curves of time-varying friction coefficient into the multi-degree-of-freedom dynamic model of spur gears. The results show that this influence is mainly embodied in the off-line-of-action direction, which is the direction of friction force acting on the tooth surface. The dynamic characteristics of gears with different surface topography are obviously different under various working conditions. The method presents in this paper simplifies the application of tooth contact analysis in the study of time-varying tooth friction characteristics, which will provide a new way for the gear dynamics research considering the tooth surface topography.

Silk fabrics have poor resistance to ultraviolet (UV) light and to wrinkles. To improve these properties, we propose a finishing method of coating the silk fabric surface with nano-silica (nano-SiO2). The results show that the UV protective factor (UPF) value could reach a maximum of 84.52 after finishing in 10 g/L nano-SiO2 and 20 g/L silane coupling agent (KH570) solution at 80℃. Moreover, the treated silk fabrics showed improved wrinkle resistance and hydrophobicity. The surface morphology and crosslink action of the treated silk fabrics were characterized by scanning electron microscope, energy dispersive spectrometer and Fourier transform infrared spectroscopy, which proved that nano-SiO2 particles were grafted on to the silk fabric. There was no apparent difference in color between untreated and treated silk fabrics. Thermal stability and cytotoxicity tests showed that the treated silk fabrics had good thermostability and cytocompatibility. The UPF value could be maintained at 77.31 after washing 20 times, which demonstrated that the treated silk fabrics had laundry resistance. Multifunctional silk fabrics with good hydrophobic properties and excellent UV and wrinkle resistance were developed, showing good prospects for their application in self-cleaning, protective and non-ironing clothes.

Recapitulating aligned cellular architectures of native tissues in vitro is important to engineer artificial tissue analogs with desired biological functions. Here a novel strategy is presented to direct three-dimensional (3D) cellular alignment by embedding cell/collagen hydrogel into the predefined electrohydrodynamically-printed microlattices. The cell/collagen hydrogel, originally filled within the printed microlattices uniformly, was found to gradually develop into densely-populated and highly-aligned bands along the longitudinal direction of the printed microlattices. The cellular alignment was highly dependent on the height, spacing and orientation of the microlattices. The presented method was applicable to multiple cell types including primary cardiomyocytes and the gaps formed between the aligned bands and the lateral walls of the microlattice facilitated the subsequent seeding and rapid alignment of other cell types which enables to engineer anisotropic multicellular tissue constructs. The engineered cardiac patches expressed mature cardiomyocyte-specific phenotypes and exhibited synchronous contractive activities. Multilayer cellular alignment with varied orientation in 3D collagen hydrogel was successfully achieved by using electrohydrodynamically-printed microlattices with layer-specific orientations. This exploration offers a promising way to engineer complex 3D tissue constructs with predefined cellular alignments. Statement of significance Fabrication of biomimetic highly-aligned complex cellular architectures has a great significance to recapitulate the unique mechanical and physiological functions of the engineered tissues (e.g., heart tissue, neuron, muscle). Here, we introduced a novel strategy to direct 3D cellular alignment by embedding cell/collagen hydrogel into the predefined electrohydrodynamically-printed microlattices without any external stimuli. The microscopical study of the dynamic alignment process of cells and collagen fibers contributed to exploring the mechanism of autonomous formation of highly-aligned cellular bands. Multilayer cellular alignment with varied orientation in 3D collagen hydrogel was successfully achieved by using the microlattices with layer-specific orientations, which showed a promising way to engineer complex 3D tissue constructs with predefined cellular alignments.

Surface quality of the perovskite layer plays an important role in the determination of the device performance. This study presents an effective method to optimize the surface morphology for the lead-free formamidinium tin iodide (FASnI3) perovskite solar cells. Poly(α-methylstyrene) (PAMS) was applied as polymer additive into the diethyl ether at different blend concentration. The addition of PAMS can apparently reduce the pinholes at the surface of the FASnI3 film without ruining the interior crystallinity of the bulk FASnI3 layer. Therefore the non-radiative carrier traps can be effectively suppressed. The surface of the FAsnI3 film becomes more hydrophobic which facilitates the consequent spin-coating of the acceptor material solution. The modification of FASnI3 film’s wettability is favorable of the photo-induced carriers’ extraction and transportation. As a result, the power conversion efficiency of the PAMS-modified devices is greatly improved.

Thermophoretic deposition of particles in turbulent duct flow is of significant relevance in energy and thermal engineering applications. However, conjugate heat transfer (CHT) was commonly not considered in the previous studies, but may have crucial influences on particle deposition behaviors. Therefore, thermophoretic particle deposition in turbulent duct flow with and without CHT was numerically investigated by using $$\overline {v{\prime ^{_2}}} - f$$ turbulence model and discrete particle model (DPM) with a modified discrete random walk method. After grid independence study and numerical verification, several important influencing factors on particle deposition velocity were studied, such as flow Reynolds number, temperature difference between inlet hot air and cool wall, thermal conductivity ratio and width ratio of solid and fluid domain. The thermophoresis greatly increases deposition velocity of small particles but has no influence on large particles. The critical particle relaxation time $$\tau _{\rm{p}}^ + $$ for thermophoresis effect is 20, which is the same for all the cases in this study. The corresponding particle diameter is 28 µm. The thermophoretic deposition is enhanced when the flow Reynolds number and temperature difference between air and wall increase. This is because the wall-normal temperature variety is higher for large Reynolds number and temperature difference, which can enhance thermophoretic deposition. However, CHT reduces the thermophoretic deposition by decreasing temperature difference in fluid region. Besides, higher thermal conductivity ratio and width ratio of solid and fluid domain will decrease the thermophoretic deposition, as thermal conduction in solid domain becomes more intense.

We design and fabricate a 350GHz 8×8 Al Microwave Kinetic Inductance Detector (MKIDs) array for the demonstration of its characteristics, mainly focus on the quasiparticle lifetime of the resonators. The quasiparticle lifetime data is collected by measuring a resonator’s phase response to a LED pulse at resonant frequency in a dilution refrigerator cooled to mK stage. We also measure and discuss the influence of various parameters on the change of quasiparticle lifetime, including different LED voltage supply, bath temperature of the MKIDs, and superconducting film thickness.

X-rays have the characteristics of high single photon energy, high frequency, and strong penetrating ability, are widely used in space communication, radiation imaging, medical diagnosis, non-destructive testing, and other fields. The development of X-rays has had a positive impact on broadening the use of the electromagnetic spectrum. As the core component of the X-ray application, high modulation rate, low power consumption, and excellent performance X-ray generators have been a hot research topic for decades. In this paper, a light-controlled pulsed X-ray source is modeled by simulation software. We perform simulation calculations and summary analysis on the effects of cathode structure, focus structure height, and metal anode voltage on the focal spot size, electron transit-time, and transit-time spread. At an operating voltage of 30KV, if the photocathode is 42mm in diameter, the focal spot diameter is about 1.5mm, the electron transit-time is 3.75ns, and the transit-time spread is 895ps when the focusing structure height is 6mm. And if the diameter of the photocathode is 12mm, the focal spot diameter is the smallest when the focusing pole height is 9mm, which is about 0.7mm, as for the time characteristics, the electron transit-time is 4.1ns, and the transit-time spread is 242ps. The results suggest that the light-controlled pulsed X-ray source is expected to be the next-generation source with easy modulation and short X-ray pulse properties.

An integrated scheme of X-ray communication and detection is proposed in this paper, which is used for the detection of the unknown target inside the coating while communication. In contrast to the X-ray communication methods reported previously, simultaneous communication and radar detection have two distinct features. One is that both communication and detection signals share the same X-ray source and channel, so the spatial resources can be effectively utilized. The other is that X-ray can penetrate the metal shielding structure and detect the internal materials effectively. In order to achieve the above goals, the propagation feasibility of an X-ray signal in space and space sparse plasma environment are first analyzed. Simulation and experiment results indicate that the X-ray carrier can realize transmission without attenuation in space environment. Then, an X-ray radar and communication demonstration system is built to verify the detection ability of coated materials. Experimental results show that when the characteristic spectrum value of the unknown target is much higher than that of the rest shell, the spatial X-ray radar system can achieve more accurate discrimination. Finally, a conclusion is reached, and some feasible detection suggestions are provided for this simultaneous detection and communication system.

Solid–liquid frictional resistance is mainly attributed to the adhesion caused by the boundary layer effect. Superhydrophobic surfaces are expected to be an effective method to reduce frictional resistance. In this paper, a rod-shaped micro-structure was prepared on surfaces of Al alloy (5083) and Ti alloy (TC4) by line-by-line scanning with nanosecond laser. The inherent properties of the metal materials—such as their coefficient of thermal conductivity (CTC) and specific heat capacity (SHC)—had a major influence on the surface morphology and shape size of the rod-shaped micro-structure. Both two metals showed apparent oxidation on their surfaces during laser ablation, however, the degree of surface oxidation of the Al alloy was greater than that of the Ti alloy due to its more fragmentary rod-shaped micro-structure. The laser-treated surfaces could turn from hydrophilic to hydrophobic or even superhydrophobic after being left in the air for 20 days, which might be caused by the adsorption of low-surface energy matter in the air. In addition, the contact angle of the Al alloy was larger than that of the Ti alloy, which is due to the larger ratio of height to width of the micro–nano composite rod-shaped micro-structure on the surface of the Al alloy.

The thermal storage stability of styrene–butadiene–styrene tri-block copolymer modified bitumen (SBSPMB) is the key to avoid performance attenuation during storage and transportation in pavement engineering. However, existing evaluation index softening point difference within 48 h (ΔSP48) cannot effectively distinguish this attenuation of SBSPMB. Thus, conventional physical indexes, rheological properties, and micro-structure characteristics of SBSPMB during a 10-day storage were investigated in this research. Results showed that during long-term thermal storage under 163 °C for 10 days, penetration, ductility, softening point, recovery rate (R%), and anti-rutting factor (G*/sinδ) were decayed with storage time increasing. This outcome was ascribed to the phase separation of SBS, which mainly occurred after a 4-day storage. However, ΔSP48 after a 6-day storage met the specification requirements (i.e., below 2.5 °C). Thus, the attenuation degree of asphalt performance in field storage was not effectively characterized by ΔSP48 alone. Results from network strength (I) and SBS swelling degree tests revealed that the primary cause was SBS degradation and base asphalt aging. Moreover, conventional indexes, including penetration, ductility, and softening point, were used to build a prediction model for rheological properties after long-term storage using partial least squares regression model, which can effectively predict I, R, Jnr, G*/sinδ, and SBS amount. Correlation coefficient is above 0.8. G*/sinδ and I at the top and bottom storage locations had high coefficient with SBS amount. Thus, phase separation of SBSPMB should be evaluated during thermal storage.

During the rolling process of thick plate, the nonlinear specific plastic power that derived from the non-linear Mises yield criterion is difficult to be integrated, which has restricted the establishment of a rolling force model. To solve this problem, a new yield criterion is firstly established, and then used to derive a linear specific plastic power. Meanwhile, a kinematically admissible velocity field whose horizontal velocity component obeys the Logistic function is proposed to describe the metal flow of the deformed plate. On these bases, the rolling energy items including the internal deformation power of the deformed body, friction power on the contact surface, and shear power on the entry and exit sections are integrated successively, and the rolling force model is established. It is proved that the model can predict the rolling force well when compared with the actual data of multicomponent alloys. Besides, the formula for predicting the outlet thickness is ultimately given upon this derived model, and a good agreement is also found between the predicted values and the actual ones, since the absolute errors between them are within 0.50 mm.

The structure–mechanochromism relationship is explored with respect to packing patterns and corresponding intermolecular interactions that are affected by the number and location of –F. The distinct and reversible mechanochormic luminescence (Δλem up to ca. 90 nm) of yellow solids (−)-1-Yg, (−)-2-Yg, and (−)-3-Yg was displayed with a simultaneous crystal-to-amorphous transformation. The change of multiple triplet excited states accounted for the mechanochormic luminescence, and a switch from the 3π,π* monomer to the excimer/3MMLCT occurred in the grinding process. The mechanical force led to perturbation in the molecular packing, and aggregates with effective Pt⋯Pt and π–π interactions were formed in the amorphous phase, leading to the variation of excited states. The mechanochromic luminescence could be reverted by dropping in CH2Cl2 and could be cycled multiple times without perceivable performance degradation. This work gives a reference for designing mechanochromic luminescent materials toward multicolor and multicomponent responses.

Glued laminated bamboo (glubam) is a type of engineered bamboo that resembles timber-based glued laminated lumber (glulam). The glubam components are made by laminating 20- to 40-mm-thick e...

Hollow-fiber membrane humidifiers were used in solar-assisted and membrane-based air humidification-dehumidification desalination systems (SMHDD) because of their greater packing density and thus better transfer efficiency. A dynamic mathematical model containing the major components of this system was established, including the membrane humidifier, dehumidifier and solar heating unit. The model was validated with test data from an experimental platform where three kinds of membranes with different membrane thickness, heat conductivity, etc., were tested. To understand the role of membrane characteristics in the proposed desalination system, the effects of the membrane moisture diffusivity (Dm), heat conductivity (λm), membrane thickness (δm) and membrane area (Atot) on the system performance were analyzed numerically. Of the three factors, Dm and Atot show the most significant effect on the accumulated freshwater production (AP) and coefficient of performance (COP), and the effects of λm on the system performance are far less pronounced than that of Dm and δm. In summary, membranes with higher moisture diffusivity and smaller thickness can improve system performance without much attention to the heat conductivity. However, further raising Dm above 3.0 × 10−6 m2/s has a slight benefit to the performance improvement. Findings in this paper are useful in guiding the preparation of membranes used for application-scale membrane-based desalination systems operating in real-world environmental conditions.

Highly effective air filters are needed because of the increasing harm caused by air particulate matter pollution. Herein, two-dimensional titanium carbide Ti3C2Tx MXene nanosheets with active surface-terminating groups (O, OH and F) were used to modify the polyacrylonitrile (PAN) nanofiber filters to strengthen their interaction force with PM2.5. These forces were measured quantitatively through the force-distance curve-based AFM showing that the MXene modification of the PAN fiber induces three times larger interaction forces than before. The obtained filters show high PM2.5 removal efficiency of ∼99.7% with a low pressure drop of ∼42 Pa. Moreover, the presence of MXene nanosheets strongly inhibits the propagation of bacteria (e.g. E. coli and S. aureus) in the filters. Such filters can significantly improve air quality, especially in public places such as hospitals.

Solar-assisted liquid desiccant dehumidification technology is attracting much attention due to lower energy consumption and less pollution. This study aims at adopting surface-modification technology to improve the dehumidification efficiency and analysing the energy saving of solar-assisted liquid desiccant air-conditioning system. Firstly a novel super-hydrophilic coating was successfully fabricated using nanoscale anatase TiO2 particles with high dispersion. The characterization of the coating was conducted using X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) test. After surface treatment, the surface free energy was significantly increased from 15.71 to 90.15 mJ/m2 and the contact angle was rapidly reduced from 90° to 10° Then, an experimental system with two single-channel plate-type liquid desiccant dehumidifiers was designed. The experimental results indicated that the falling film shrinkage of desiccant solution was effectively prevented and the contact area was rapidly increased by the novel coating. The maximum wetting ratio was increased from 75% to almost 100%. The influence of operating parameters on heat and mass transfer performance was comprehensively analysed. To better evaluate the benefits of the surface-modification technology, a dynamic model of solar-assisted liquid desiccant air-conditioning system was developed. The simulation results indicated that 9% (94MW · h) of electricity could be saved. This finding is very useful in other falling film applications, such as heat exchangers and cooling towers to improve the efficiency and reduce the energy consumption.

A striking feature of lyotropic chromonic liquid crystals confined in cylinder model exhibit double-twist director configurations. Evidence suggests that saddle-splay deformation is among t...

Interface modification is an effective strategy to improve the performance of perovskite solar cells (PSCs). In this work, edible materials like glycerol and choline chloride were used to modify the surface of hole transport layer (HTL) NiOx. CH3NH3PbI3 (MAPbI3) film fabricated on the modified NiOx has a smoother surface and more uniform grains. It enables an improvement in short-circuit current density (JSC) of PSC from 17.77 ± 0.18 to 20.35 ± 0.36 mA cm−2, leading to an enhancement of power conversion efficiency from 13.37 to 15.25%. The work mechanism of glycerol and choline chloride modification was discussed. Our work provides an efficient and environmentally friendly choice for interface modification.

Dust deposition on solar photovoltaic (PV) panels would greatly reduce the PV output efficiency, especially in dusty regions. This paper investigated dust deposition reduction on solar cell covering glass by transparent super-hydrophobic coating under different PV tilted angles. The macroscopic and microscopic dust deposition patterns, dust deposition density, spectral transmittance of covering glass and PV efficiency reduction caused by dust deposition were studied and analyzed. The results showed that dust deposition on the glass surface can be greatly reduced by super-hydrophobic coating due to the low adhesion energy. The super-hydrophobic coating has a better performance on dust deposition reduction compared with hydrophobic coating. The deposition density on the glass with super-hydrophobic coating is just 44.4%, 28.6% or 11.2% of the bare surface for tilt angle θ = 30°, θ = 45° or 60°, respectively. The spectral transmittance of coated glass and the PV efficiency are obviously higher compared with bare glass case after dust deposition. Moreover, the self-cleaning coating has better performance for large tilt angle and poly-crystalline silicon PV cell. The performance of super-hydrophobic coating on dust deposition reduction is similar between the test dust and the real dust obtained from Guangzhou, China.

Dust deposition on the solar photovoltaic (PV) modules would greatly decrease the spectral transmittance of the covering glass and result in a significant reduction of PV output efficiency. In this paper, the dust deposition reduction on solar cell covering glass by different self-cleaning coatings was investigated by experimental measurement. Four glass samples were used in the study: the bare glass (glass sample A), the glass coated by hydrophobic silica sol (glass sample B), the glass coated by ethanol solution with SiO2 nano-particles (glass sample C) and the glass coated by silica sol with SiO2 nano-particles (glass sample D). The microscopic patterns of dust deposition, dust deposition density, spectral transmittance reduction and PV efficiency degradation of the four glass sample cases were studied in details. When the dust deposition time is 60 min and the tilt angle of glass sample is θ = 30°, the dust deposition density on the glass sample B, C or D is just 51.4%, 38.6% or 36.1% of the bare glass sample A, respectively. The super-hydrophobic coating with micro-nano structures (glass sample D) achieves the highest spectral transmittance and the lowest PV power efficiency reduction after dust deposition.

A molecular dynamics simulation (MDS) technique is used to study the heat and mass transfer inside the composite PVDF (polyvinylidene fluoride)/SiO2 (Si aerogel) bilayer membrane at molecular level. The reverse non-equilibrium molecular dynamics (RNEMD) simulation method is employed to determine the thermal conductivity at each layer and at the interface. Moisture diffusivity is also modeled by the mean square displacements (MSD) of water vapor in the materials. In combination with macro scale resistance models for porous media, the heat conductivity and moisture diffusivity through the whole membrane are calculated. It is found that the interface has a great influence on the membrane overall resistance, especially for thinner membranes. Molecular groups can be manipulated to adjust this resistance. When the hydroxyl groups are increased from 58% to 100%, the membrane overall heat conductivity can be increased by 57%, and the diffusivity can be increased by 48%. The fractional free volume, vibrational density of states (VDOS), adhesion energy, thermal and moisture resistance in each layer and at the interface are investigated to disclose the transport mechanisms. Membranes of low conductivity and high moisture diffusivity that are desired for air humidification applications can be obtained by such molecular level manipulations. By this work, a multi-scale model for interfacial heat and mass transfer resistance between two contacting materials, that considers both macro-scale roughness and porosity and micro-scale molecular interacting, is provided.

In this study, we developed a simple route to fabricate natural silkworm cocoon composites with dense fiber networks and low porosities. The thermal and mechanical properties of these modified cocoons are significantly improved. Especially, the tensile strength, elongation, toughness and the average peeling force of the cocoon constructed by three silkworm larvae simultaneously are found to be 1.7, 1.5, 2.1 and 2.1 times higher than those of the normal cocoon, respectively. These special cocoons with good mechanical properties could be applied to produce high-performance artificial cocoon composites, biomimetic and ballistic materials.

Membranes with high hydrophobicity and moisture permeability are highly desired for preventing membrane wetting in membrane distillation type seawater desalination. To solve the membrane wetting problems and maintain high moisture permeability simultaneously, a new block composite membrane (GO PVP GO) was prepared by connecting graphite oxide (GO) sheets to polyvinylpyrrolidone (PVP). First, octadecyl amine (ODA) was functionalized with GO to form a micro/nanoscale hierarchical structured surface. Then, it was mixed with a PVP solution to form a new block composite membrane. Finally, the membrane was modified by low-surface-energy hexadecyltrimethoxysilane (HTEOS). At the suitable ratio of GO and PVP, the optimal arrangement of GO nanosheets was obtained, achieving the highest vapour permeation. Then, the structural parameters and moisture permeability of the novel membrane were analysed and characterized. Desalination with real seawater from South China Sea coast was performed. Compared to the virgin PVDF membrane, the novel membrane shows a similar permeability but a much higher hydrophobicity with the contact angle of 145.2° and a more negative zeta potential. The new membrane can significantly reduce the adsorption of negative proteins. It exhibits excellent outstanding salt rejection with high flux, when used to desalinate real coastal seawater. The present membrane may be useful for improving the seawater desalination efficiency.

PEM-based electrolytic air dehumidification is innovative due to its high efficiency, compact size and cleanness. However, high polarization loss and severe performance degradation have been observed, especially at high applied voltages (>2.5 V). Understanding the V–I characteristics is critical to performance optimization. This study experimentally investigated the V–I characteristics and internal response of materials under various operating conditions, with in-situ Electrochemical Impedance Spectroscopy (EIS) methods. Real-time mass transfer, electrochemical polarization and reaction dynamics of PEM components during dehumidification were derived by EIS. Then, a fast prediction model was built to directly predict the dehumidification rate and attenuation without any iteration, suitable for online monitoring and adjustment. Compared to other models, this model can take a quick understanding of the impact of operating conditions on the material characteristics inside the PEM element. The deviations of current density, PEM proton conductivity and moisture removal were 3%, 11.2% and 15.3%, respectively, compared to experiment data. Results showed that when the applied voltage changed from 1.5 to 3.5 V, the high-frequency resistance of the PEM element increased from 1.69 to 2.69 Ω, and the PEM proton conductivity decreased by about 38 times. The sharp drop in PEM proton conductivity resulted in a current attenuation. With this model, requirements for key components of PEM dehumidification were also obtained. Analysis of the overpotential distribution showed that increasing the water retention and reducing the dependence of proton conductivity on water molecules of the PEM can effectively improve the performance. This research provides guidance for the performance optimization and material selection of PEM-based dehumidification.

Flame-retardant silane-grafted-graphene oxide (silane-GO) papers are fabricated via a green and versatile silane-assisted assembling strategy, and their use as early fire alarm sensors are investigated. Different silane molecules with alkoxy groups can react with GO in aqueous solution via hydrolysis and condensation reactions and thus assemble into the aligned silane-GO papers. The silane-GO papers exhibit good mechanical flexibility, strong acidic/alkaline tolerance, excellent flame resistance and improved thermal stability at low silane content in comparison with pure GO paper. Structure observation and analysis disclose that a compact nano-silica protective layer transformed from the grafted silane molecules during combustion is formed to inhibit the thermal degradation of GO sheet effectively. Furthermore, the insulating silane-GO paper can be thermally reduced into the conductive reduced GO network after encountering high-temperature or flame situation, thus providing ideal early fire alarm response, i.e. rapid flame detecting response time of ∼1.6 s and fire early warning response of ∼5 s when attach on the heat resistor. These results suggest that the silane-GO papers are promising for development of advanced materials as smart sensors in early fire alarm applications.