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It is a challenge to maintain the mechanical properties and processability of thermally conductive polymer composites in the presence of high filling of heat conductive filler. An optimized hybrid filler system composed of flake graphite (FG), expanded graphite (EG) and short carbon fiber (CF) was introduced into PA6 matrix. The addition of EG to PA6 was found to be more effective in improving its thermal conductivity, while the addition of FG maintained favorable processability due to its lubrication effect. Furthermore, the hybrid filling of FG and EG has a synergistic effect on the enhancement of thermal conductivity. The ternary filling of FG, EG and CF produced highly heat conductive PA6 composites with high strength, favorable processability, and low water absorption. The thermal conductivity of 10CF/20FG/10EG/PA6 composite reached 3.45 W/m k, which is 12.3 times of pure PA6. Additionally, the flexural strength increased to 110 MPa, which is 37 % higher than that of pure PA6, and the water absorption was reduced to one quarter that of pure PA6. [ABSTRACT FROM AUTHOR]

Many cultural and heritage structures are constructed using timber materials in China. Timber buildings are very common in historic and cultural blocks and rural areas of Southwest China. Many of them have been destroyed during fire and exert an inestimable loss to people and society. This work is aimed at investigating the temperature distribution, flame and smoke behavior within timber compartments. A full-scale experiment was built and carried out. The timber building groups consist of four compartments placed in two platforms of different heights. Temperature profiles were obtained by thermocouples arranged at corresponding positions. Fire behavior both in and out of compartments, as well as structural failure, were examined. A smoke detection system was applied to record the arrival time of smoke at a specific position. Cameras were also employed to observe and record the fire growth. The potential route of smoke is revealed. The results suggest that not only the common route of smoke should be taken into consideration in designing smoke detection systems but also the unconventional path of the gaps. The obtained data of temperature profiles will provide useful information for the prevention of historic and cultural timber buildings in Southwest China. [ABSTRACT FROM AUTHOR]

Single photon emission of quantum emitters (QEs) carrying internal degrees of freedom such as spin and angular momentum plays an important role in quantum optics. Recently, QEs in two-dimensional semiconductors have attracted great interest as promising quantum light sources. However, whether those QEs are characterized by the same valley physics as delocalized valley excitons is still under debate. Moreover, the potential applications of such QEs still need to be explored. Here we show experimental evidence of valley symmetry breaking for neutral QEs in WSe2 monolayer by interacting with chiral plasmonic nanocavities. The anomalous magneto-optical behaviour of the coupled QEs suggests that the polarization state of emitted photon is modulated by the chiral nanocavity instead of the valley-dependent optical selection rules. Calculations of cavity quantum electrodynamics further show the absence of intrinsic valley polarization. The cavity-dependent circularly polarized single-photon output also offers a strategy for future applications in chiral quantum optics. The microscopic origin and valley physics of quantum emitters (QEs) in 2D semiconductors are still not fully understood. Here, the authors report an anomalous magneto-optical behaviour of QEs in WSe2 monolayers coupled to chiral plasmonic nanocavities, suggesting the absence of intrinsic valley symmetry of the emitters. [ABSTRACT FROM AUTHOR]

To study the explosion characteristics of coal dust samples with different metamorphism, 19 coal samples including anthracite, bituminous coal, lignite were selected, explosion pressure distribution and flame propagation velocity were studied in an explosion pipeline with an outer diameter of 108 mm and an inner diameter of 88 mm. Coal dust particles were injected into the pipeline by eight dust nozzles controlled by solenoid valves. The explosion pressure and flame propagation profiles were obtained by PCB piezoelectric sensors and photoelectric sensors. The experimental results suggested that the explosion pressure profiles of different coal samples are all present a first increasing and then decreasing trend. However, there is a drop point at 0.875 m from the ignition end. The flame propagation velocity increases first and reaches the maximum at 0.625 m from the ignition end, and then the propagation velocity begins to decrease until the end of the pipeline, while there exist a slight enhancement at 1.105 m from the ignition end. Furthermore, the coal samples with different coal ranks have different explosion severity, coal samples with lower moisture content, and relatively higher volatile matter present a better deflagration property and cause a higher explosion severity. [ABSTRACT FROM AUTHOR]

AbstractDust explosions are common and highly hazardous industrial accidents that occur rapidly and involve complex changes in particle structure. Traditional experimental methods struggle to capture the time-resolved information of the explosion process, limiting the in-depth study of its dynamic mechanisms. Synchrotron radiation small-angle x-ray scattering (SAXS) offers a novel method to study the microscopic dynamics of dust particles during explosions. Utilizing high-flux x-rays from synchrotron facilities, coupled with fast detectors and specialized explosive chambers, SAXS provides high temporal and spatial resolution alongside nondestructive detection capabilities. It is expected to obtain information on particle morphology changes during dust explosions. This contribution first introduces the basic characteristics and hazards of dust explosions, reviews the current research status and challenges, and then expounds on the basic principles and advantages of synchrotron radiation SAXS. Finally, the potential of this method in real-time monitoring of dust explosion characteristics and enhancing understanding of explosion mechanisms was explored. [ABSTRACT FROM AUTHOR]

Wet flue gas denitrification offers a new route to convert industrial nitrogen oxides (NO x ) into highly concentrated nitrate wastewater, from which the nitrogen resource can be recovered to ammonia (NH 3 ) via electrochemical nitrate reduction reactions (NITRRs). Low-cost, scalable, and efficient cathodic materials need to be developed to enhance the NH 3 production rate. Here, in situ electrodeposition was adopted to fabricate a foamy Cu-based heterojunction electrode containing both Cu-defects and oxygen vacancy loaded Cu 2 O (OVs-Cu 2 O), which achieved an NH 3 yield rate of 3.59 mmol h -1 cm -2 , NH 3 Faradaic efficiency of 99.5%, and NH 3 selectivity of 100%. Characterizations and theoretical calculations unveiled that the Cu-defects and OVs-Cu 2 O heterojunction boosted the H* yield, suppressed the hydrogen evolution reaction (HER), and served as dual reaction sites to coherently match the tandem reactions kinetics of NO 3 -to-NO 2 and NO 2 -to-NH 3 . An integrated system was further built to combine wet flue gas denitrification and desulfurization, simultaneously converting NO and SO 2 to produce the (NH 4 ) 2 SO 4 fertilizer. This study offers new insights into the application of low-cost Cu-based cathode for electrochemically driven wet denitrification wastewater valorization.