The p-n junction is the foundation building structure for manufacturing various electronic and optoelec-tronic *** bandgap semiconductors are expected to overcome the limited power capability of Si-based electronic de...
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The p-n junction is the foundation building structure for manufacturing various electronic and optoelec-tronic *** bandgap semiconductors are expected to overcome the limited power capability of Si-based electronic device,however,it is very difficult to achieve efficient bipolardoping due to the asymmetric doping effect,thereby impeding the development of p-n homojunction andrelated bipolardevices,especially for the Ga2O3-based materials and ***,we demonstrate a unique one-step integrated growth of p-type N-doped(201)β-Ga2O3/n-type Si-doped((2)01)β-Ga2O3 films by phase tran-sition and in-situ pre-doping of dopants,and fabrication of full β-Ga2O3 linearly-graded p-n homojunc-tion diode from *** full β-Ga2O3 p-n homojunction diode possesses a large built-in potential of 4.52 eV,a high operation electric field＞2.90 MV/cm in the reverse-bias regime,good longtime-stable rectifying behaviors with a rectification ratio of 104,and a high-speed switching and good surge robust-ness with a weak minority-carrier charge *** work opens the way to the fabrication of Ga2O3-based p-n homojunction,lays the foundation for full β-Ga2O3-based bipolardevices,and paves the way for the novel fabrication of p-n homojunction for wide-bandgap oxides.
This study explores the application of Chebyshev ridge structures in the optimization of absorbing materials within microwave anechoic chambers, aiming to enhance absorption performance and improve antenna testing acc...
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This study explores the application of Chebyshev ridge structures in the optimization of absorbing materials within microwave anechoic chambers, aiming to enhance absorption performance and improve antenna testing accuracy by integrating Fresnel zone theory. The research employs geometric diffraction theory to analyze electromagnetic wave reflection behavior at different frequencies and optimizes the layout of absorbing materials within the chamber. Simulation results indicate that the introduction of Chebyshev ridge structures significantly reduces the reflection level in the quiet zone, with a decrease of over 10 dB across all frequency bands. The measuredreflection levels and tapering in the quiet zone of the chamber constructed with this optimizeddesign meet the requirements for far-field antenna testing. Compared to traditional designs, this optimization effectively minimizes reflection interference andreduces material costs. The findings provide a theoretical foundation and practical reference for the design and engineering application of absorbing materials in microwave anechoic chambers.
Nanostructured WO3 has excellent NOx gas-sensing properties, but its selectivity still needs to be further improved. By modulating the concentration of adjuvant H2C2O2 in the hydrothermal method, the morphology of the...
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Nanostructured WO3 has excellent NOx gas-sensing properties, but its selectivity still needs to be further improved. By modulating the concentration of adjuvant H2C2O2 in the hydrothermal method, the morphology of the samples can be dramatically changed from microspheres to nanoribbons. The results also show that, for the growth of WO3 nanoribbons, the concentration of the structural directing agent, K2SO4 , is important and sensitive. Next, we propose a mechanism to explain the growth fordifferent nanostructures of WO3, which should be a sulfate-induceddirectional attachment growth in a proper chemical environment by adjuvant H2C2O2. The formation of nanoribbons mainly depends on the competition and balance between the reaction environment and the guiding agents. Furthermore, the NO sensing performance of the WO3 nanoribbons and microspheres have also been systematically investigated. The results showed that WO3 nanoribbons has a better NO response, which may originate from theirribbons-like morphology and high crystallinity. At the optimal operating temperature of 140 degrees C, the WO3 nanoribbon sensor showed a best response to 5 ppm NO (r-g/r-a = 112) and had a good NO response selectivity. Ourresults demonstrated that WO3 nanoribbons are a promising gas sensor for NO. It will be helpful to further study the synthesis of different WO3 nanostructures and their gas-sensing applications.
Graphene, owing to its exceptional electronic, optical, thermal, and mechanical properties, has emerged as a highly promising material. Currently, the synthesis of large-area graphene films on metal substrates via che...
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Graphene, owing to its exceptional electronic, optical, thermal, and mechanical properties, has emerged as a highly promising material. Currently, the synthesis of large-area graphene films on metal substrates via chemical vapordeposition remains the predominant approach for producing high-quality graphene. To realize the potential applications of graphene, it is essential to transfer graphene films to target substrates in a manner that is non-destructive, clean, and efficient, as this significantly affects the performance of graphene devices. This review examines the current methods for graphene transfer from three perspectives: non-destructive transfer, clean transfer, and high-efficiency transfer. It analyzes and compares the advancements and limitations of various transfer techniques. Finally, the review identifies the key challenges faced by current graphene transfer methods and anticipates future developmental prospects.
The diffusion of nano-confined fluids plays a crucial role in nano-energy research. We developed three molecular models to calculate the diffusion behavior of both supercritical water (SCW) at 673-1173 K, 250 atm, and...
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The diffusion of nano-confined fluids plays a crucial role in nano-energy research. We developed three molecular models to calculate the diffusion behavior of both supercritical water (SCW) at 673-1173 K, 250 atm, androom water (300 K, 1 atm), confined in carbon nanotubes (CNTs) ranging from 9.49 to 50.17 & Aring;. We analyzed the diffusion mechanism of water confined in various CNTs using the time coefficient. We calculated the self-diffusion coefficient of water in Fickian-like diffusion mode and examined the factors influencing it. The results indicate that in small-diameter CNT (7,7), SCW primarily follows a Fickian-like diffusion mode, while room temperature (300 K, 1 atm) water exhibits a superdiffusion mode. For CNT diameters larger than 20 & Aring;, both room temperature water and SCW predominantly exhibit Fickian-like diffusion. Additionally, the self-diffusion coefficient of SCW increases linearly with temperature, displaying clear Arrhenius behavior. The self-diffusion activation energy of SCW in different types of CNTs shows a strong correlation with the hydrogen bond structure. Finally, we combined the saturatedrelationship between CNT diameter and self-diffusion coefficient to propose a predictive model for the self-diffusion coefficient of confined SCW. The model is simple, requiring only three parameters, with a mean absolute relative error of less than 6.5%.
The changes of digestibility, several processing properties, and structure of highland barley starch induced by dry heat treatment (dHT), heat moisture treatment (HMT), and annealing treatment (AT) were investigated. ...
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The changes of digestibility, several processing properties, and structure of highland barley starch induced by dry heat treatment (dHT), heat moisture treatment (HMT), and annealing treatment (AT) were investigated. And the interrelationship between modification conditions, structure, and functional properties was also investigated. FordHT, the starch was treated at 110 degrees C for 4 , 8, and 12 h, respectively. For HMT, the starch was adjusted to moisture contents of 20%, 25%, and 30%, and then heated at 110 degrees C for 4 h. For AT, the starch was treated at 50 degrees C for 12 and 24 h, respectively. The results indicated that dHT, HMT and AT all positively impacted the total content of slowly digestible starch (SdS) andresistant starch (rS) in the starch samples, and HMT was the best method in leading to the conversion of a portion of rapidly digestible starch (rdS) into SdS andrS. Among them, HMT-20% resulted in a decrease in the rdS content from 91.19% to 81.50%, while simultaneously causing an increase in the SdS andrS content from 5.54% and 3.27% to 8.73% and 9.77%. Moreover, HMT significantly affected the thermal properties, rheological properties, crystallinity, molecular structure, and particle morphology of starch. Therefore, ourresearch suggested that utilizing hydrothermal treatment or heat treatment could be a potential approach for controlling the digestibility of starch products according to desired specifications. This experiment innovatively focused on highland barley starch, a less-researched material. Using dHT, HMT, and AT, it measureddifferent digestible starch contents and explored the links between treatment conditions, rS contents, structure, and function, providing new ideas for its application in functional foods.
Biodiesel has a higher viscosity and poorer atomization effect compared to traditional diesel fuel, resulting in lower combustion efficiency. This study investigated the effects of exhaust gas recirculation and a diet...
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Biodiesel has a higher viscosity and poorer atomization effect compared to traditional diesel fuel, resulting in lower combustion efficiency. This study investigated the effects of exhaust gas recirculation and a diethyl carbonate additive on the combustion and emission of biodiesel blends. Biodiesel was blended with dEC (90% volume biodiesel + 10% volume dEC: B90dEC10). Experiments were conducted at various brake mean effective pressures (BMEP: 0.2, 0.6, 1.0, 1.6, and 2.0 MPa) and EGrrates (0, 5, and 15%) on a direct injection and high pressure common rail diesel engine that met Euro VI emission standards. The results revealed that the viscosity and atomization effects of B90dEC10 were improved, and the premixed combustion period was longer and the heat release rate (Hrr) was higher compared to traditional diesel. The maximum Hrr of B90dEC10 was 20% higher than that of diesel at 0.6 MPa. Compared to diesel, the particulate matter emissions of B90dEC10 were reduced by 92%, and total hydrocarbons and carbon monoxide emissions were significantly reduced. However, there was an increase of 8-20% in nitrogen oxide emissions. At an EGrrate of 15%, the NOx emissions of B90dEC10 were reduced by 45%, while having minimal impact on PM emissions and brake thermal efficiency. Therefore, it was concluded that B90dEC10 is a potential alternative to diesel, and the combustion performance and emissions control were optimized when using a higher EGrrate (15%).
The wide applications of continuous silicon carbide fiber (SiCf) are constrained by the high cost of its common raw material, polycarbosilane (PCS). Polymethylsilane(PMS) exhibits higherreactivity and a lower product...
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The wide applications of continuous silicon carbide fiber (SiCf) are constrained by the high cost of its common raw material, polycarbosilane (PCS). Polymethylsilane(PMS) exhibits higherreactivity and a lower production cost than PCS. Nevertheless, the disadvantages of pyrophoric nature and thermoset properties in raw PMS necessitate improvements for practical applications. Herein, benzoxazine resin (VBr) with vinyl functional groups is utilized to modify PMS via hydrosilylation. After modification, a stable preceramic polymer with excellent processability is obtained. The ordered and symmetrical molecular architecture of the initial PMS is changed. This results in an increase of the molecularrigidity, which in turn constrains the alteration of molecular conformation anddiminishes the tendency toward crystallization. The modified PMS exhibits a shear-thinning behavior and thermoplastic properties upon heating, making it suitable for melt-spinning. The molecular orientation of the newly formed network structure in the modified PMS is aligned with the shear force during melt-spinning, facilitating the extrusion of green fibers and thereby imparting superior spinnability to the modified PMS. By optimizing the temperature of melt-spinning to 210 degrees C, we produce continuous SiC green fibers with lengths exceeding 10 km. This work presents a promising candidate for the economic preparation of SiC fiber.
The spatial-temporal structures of bottom reverberation are associated with seafloor features. In a bistatic bottom reverberation experiment involving a vertical transmitting array and a towed horizontal receiving arr...
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The spatial-temporal structures of bottom reverberation are associated with seafloor features. In a bistatic bottom reverberation experiment involving a vertical transmitting array and a towed horizontal receiving array, stable stripe structures were observed within the beam-time domain. In this study, a bistatic reverberation model based on ray theory is presented to interpret the experimental phenomena. The conventional empirical scattering function is primarily applicable to small grazing angles. Moreover, the regional segmentation method simulates reverberations across various receiving beams, ignoring scatterers in other areas. To address these issues, we substitute the empirical scattering function with a small-slope approximation (SSA) that is appropriate for full grazing angles. Furthermore, we utilize the beam pattern of arrays to incorporate the effects of each scatterer, andderive the expression for bottom reverberation intensity in both the array and beam domains. The established model demonstrates its applicability in simulating and interpreting the stripe structures of bottom reverberation, and the comparison shows that the model outputs are in agreement with the experimental results. The analysis indicates that the vertical stripes within the structures originate from eigenrays in the mirrorreflection direction. Furthermore, the convex stripes are predominantly affected by the direct ray and the surface reflection ray among the scattered eigenrays, whereas the concave and elliptical stripes are primarily affected by the bottom-surface reflection ray and the surface-bottom-surface reflection ray within the scattered eigenrays.
Electrokinetic remediation (EKr) is a proficient, environmentally friendly separation technology for in-situ removal of contaminants in soil/sediment, distinguished for its ease of implementation and minimal prerequis...
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Electrokinetic remediation (EKr) is a proficient, environmentally friendly separation technology for in-situ removal of contaminants in soil/sediment, distinguished for its ease of implementation and minimal prerequisites compared to otherremediation technologies. To comprehensively understand the research focus and progress related to EKr of contaminated soil/sediment, a bibliometric analysis was conducted on 1593 publications retrieved from the Web of Science Core Collection (WOSCC) database. This analysis utilizeddata mining and knowledge discovery techniques through Bibliometrix, VOSviewer, and CiteSpace software. The results revealed a rising trend in annual publication numbers, with china leading in the number of publications. The primary journals in this field included the Journal of Hazardous Materials, Chemosphere, and Separation and Purification Technology. The primary disciplines contributed to this field included "Environmental Sciences", "Engineering, Environmental", "Engineering, Chemical", and "Electrochemistry". keyword co-occurrence and burst analysis indicated that current EKr-relatedresearch mainly focuses on the remediation of soil/sediments contaminated by heavy metals (HMs) and organic pollutants (OPs). Furthermore, the EKrremediation improvement method emerged as the prevailing and future research hotspots anddevelopment directions. Future research could integrate numerical simulations and various methodologies to predict and assess the migration of pollutants and the efficiency of remediation efforts. Additionally, these studies could explore the effects of EKr on the physicochemical properties and microbial diversity of soil/sediment to provide a theoretical foundation for applying EKr in soil/sediment remediation.
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