混配柴油凝点及溶解度参数的分子模拟研究

石化柴油中添加少量生物柴油调配混配柴油是当前研究的一个热点.分别用单组分、3组分和5组分正构烷烃构建石化柴油模拟系统,以亚油酸甲酯（ML）构建单组份生物柴油模拟系统.按2％、4％、6％、8％和10％物质的量比添加ML于石化柴油模拟系统中构建不同比例的混配柴油系统.利用分子动力学方法对各种系统的凝点区间及溶解度参数进行了模拟计算.利用热容等4个性质联合判断出各系统的模拟凝点区间,发现,随着ML的添加,系统的凝点总体呈下降趋势,说明生物柴油确具有明显的降凝效果,添加生物柴油可以使柴油的低温流动性增加.相比较而言,采用3组分正构烷烃构建石化模拟系统更为合适.通过对293 K时3组分石化柴油系统添加不同比例的ML构成的混配柴油系统的溶解度参数进行分析,得出了当添加比例为4％时两种油品的相容性最佳的结论.     

Mo、Ni含量与Ti(C,N)基金属陶瓷组织和性能之间的关系

本文研究了Mo、Ni含量对Ti（C，N）基金属陶瓷组织和性能的影响．结果表明，Mo、Ni含量对组织和性能有很大影响，化学成分决定了组织和性能．     

High efficient separation of olefin from fluid catalytic cracking naphtha: Separation mechanism and universal simulation method

The fluid catalytic cracking (FCC) naphtha critical component-oriented separation process is an efficient method to produce ultra-low-sulfur (<10 μg/g) gasoline with minimal loss of octane number (<1 RON). However, the product quality is highly dependent on the structure of the components of FCC naphtha. Aromatics and thiophene sulfides without a methyl side chain favor the separation of olefin. The major impulse of olefin separation is the solvent-induced dipole of aromatics or thiophene sulfides, leading to a “Plane-to-Plane” combination between the solvent and aromatics or thiophene sulfides, accompanied by a steric hindrance due to their side chains. This condition resulted in 2–3 times greater θ of benzene and thiophene compared with that of toluene and 3-methylthiophene. In addition, an improved non-random two-liquid model was proposed based on the above results, and a simulation method for FCC naphtha solvent extraction process was established. The calculation results accorded well with industry data.     

Electromagnetic wave absorbing properties of Cr2AlB2 powders and the effect of high-temperature oxidation

The electromagnetic (EM) wave absorbing properties of Cr₂AlB₂ powders and those after high-temperature oxidation were investigated. Coupling of magnetic and dielectric loss enables Cr₂AlB₂ with good absorption properties. The minimum reflection loss (RL) value is −44.9 dB at 8.5 GHz with a thickness of 2.7 mm, and the optimized effective absorption bandwidth (E_AB) is 4.4 GHz (13.0-17.4 GHz) with a thickness of 1.6 mm. After oxidation at 750, 900, and 1000°C for 2 h, the minimum RL values, respectively, are −23.9 dB (17.5 GHz, 1.5 mm), −41.4 dB (16.5 GHz, 1.5 mm), and −39.5 dB (8.0 GHz, 3.0 mm); and the corresponding E_AB values, respectively, are 3.8 GHz (13.6-17.4 GHz, 1.7 mm), 4.1 GHz (13.5-17.6 GHz, 1.6 mm), and 4.4 GHz (13.0-17.4 GHz, 1.7 mm). With an absorber thickness of 1.5-4.0 mm, the E_AB with a RL value of less than −10 dB can be tuned in a broad-frequency range 5.0-18.0 GHz, which basically covers C (4-8 GHz), X (8-12 GHz), and Ku (12-18 GHz) bands. These results demonstrate that Cr₂AlB₂, as a high-efficient and oxidation-resistant absorber, is a promising candidate for microwave absorption applications and can retain good EM wave absorbing properties after high-temperature oxidation.     

Surface plasmon resonance-induced Ag-BaTiO3 composites for catalytic performance

Ferroelectric BaTiO₃ was combined with Ag nanoparticles for piezocatalytic and photocatalytic viewpoints. Microstructural characterization (X-ray diffraction and electron microscopy images) revealed that the Ag was successfully bounded with BaTiO₃. X-ray photoelectron spectrum also confirmed the presence of Ag. Further, its performance was examined for dye degradation under visible light (for photocatalysis) and ultrasonication (for piezocatalysis). In both the catalysis processes, there was a significant improvement in Ag-loaded BaTiO₃ sample-based catalytic reactions. Catalytic performance was evaluated for multiple cycles and was found consistent. Scavenger tests were also performed to understand catalytic reactions.     

The effect of washing process on the cracking of ZrO2 microspheres by internal gelation

ZrO₂ microspheres are widely used as a simulant of UO₂ in the development of nuclear fuel. However, the cracking of ZrO₂ microspheres prepared by internal gelation is still a challenge during drying and sintering processes. To address this issue, we designed and optimized the washing process for obtaining crack-free ZrO₂ microspheres. Through thermogravimetric, infrared, Raman, BET, and SEM analysis, it is shown that the cracking of the microspheres is mainly related to the pores in microspheres. The washing solvent with low surface tension is used to reduce the effect of capillary force on pore shrinkage. Therefore, the optimal washing process was designed as trichloroethylene (TCE)—0.5 M NH₃.H₂O—Propylene glycol methyl ether (PM) and gel microspheres with a high specific surface area of 315.3 m²/g and pore volume of 0.4125 cm³/g were obtained. The characterizations also further showed that when the microspheres were dried and sintered, the water vapor and the decomposition gas of organic matter were completely released from the pores in the microspheres. Our new washing process could be directly extended for preparing crack-free ceramic microspheres by internal gelation.     

Broadband excited Na3Tb(PO4)2:Ce3+/Eu2+ green/yellow-emitting phosphors with high color purity for LED-based application

To enhance the display quality of light-emitting diodes (LEDs), it is of great significance to exploit green/yellow-emitting phosphors with narrow emission band, high quantum yield, and excellent color purity to satisfy the application. Herein, orthophosphate-based green/yellow-emitting Na₃Tb(PO₄)₂:Ce³⁺/Eu²⁺ (NTPO:Ce³⁺/Eu²⁺) phosphors have been successfully synthesized by a facile solid-state reaction method. The absorption band of NTPO samples was extended to the near-ultraviolet region and the absorption efficiency was significantly improved owing to a highly efficient energy transfer from Ce³⁺/Eu²⁺ ion to Tb³⁺ ion in NTPO host certified by time-resolved PL spectra. Upon 300 nm excitation, the NTPO:Ce³⁺ is characterized by ultra-narrow-band green emission of Tb³⁺ with an absolute quantum yield of 94.5%. Unexpectedly, NTPO:Eu²⁺ emits bright yellow light with a color purity of 73% as a result of the blending of green light emission from Tb³⁺ and red light emission from Eu³⁺. The thermal stability has been improved by controlling the stoichiometric ratio of Na⁺. The prototype white LED used yellow-emitting NTPO:Eu²⁺ phosphor has higher color-rendering index (Ra = 83.5), lower correlated color temperature (CCT = 5206 K), and closer CIE color coordinates (0.338, 0.3187) to the standard white point at (0.333, 0.333) than that used green-emitting NTPO:Ce³⁺ phosphor, indicating the addition of the yellow light component improved the Ra of the trichromatic (RGB) materials.     

High extinction-ratio microstructure fiber based on chalcogenide glasses

Extinction ratio (ER) is one of the important parameters to characterize the polarization-maintaining (PM) performance of the fiber. In this paper, we report the preparation and properties of a novel chalcogenide microstructure fiber with a high ER. We fabricate a preform using a peeled-off extrusion method. The core and cladding material of the fiber are Ge₉As₂₃Se₆₈ and Ge₁₀As₂₂Se₆₈. The preform was drawn into a fiber with an average ER of −17.08 dB. The loss of the fiber is less than 2 dB over 5.20–8.55 μm, and the minimum loss of the fiber is 0.57 dB/m at 6.2 μm. Moreover, a flat mid-infrared supercontinuum spectrum spanning from 1.53 to 12.50 μm is generated by pumping an 18-cm-long PM fiber for the first time.     

A novel spherical-ordered macroporous CuO nanocatalyst for the electrochemical reduction of carbon dioxide

Journal of Applied Electrochemistry - The electrocatalytic reduction of CO2 is a promising research direction in resource utilization and sustainable energy development. However, there is still a...     

Si/CNTs@melamine-formaldehyde resin-based carbon composites and its improved energy storage performances

In this paper, Si/carbon nanotubes@melamine-formaldehyde resin (MFR)-based carbon (Si/CNTs@C) composites have been fabricated by surface modification, electrostatic self-assembly, cross-linking of MFR under hydrothermal treatment and further carbonization. The microstructure of the Si/CNTs@C composites was characterized, and the effects of CNTs content in Si/CNTs@C composites on their electrochemical performances were also investigated in detail. The results indicate Si/CNTs@C composites as anode materials of Li-ion batteries exhibit better high-rate and cycling performances compared to Si and Si@MFR-based carbon composites. Notably, Si/CNTs@C composites with 10.4 wt% CNTs show specific capacities of 1900, 1879, 1,688, 1,394, 1,189 mAh·g⁻¹ at 0.2, 0.5, 1, 2, and 3 A·g⁻¹, respectively. Even at 4 and 5 A·g⁻¹, their capacities still reach 970 and 752 mAh·g⁻¹, respectively. Moreover, they deliver a reversible capacity of 1,184 mAh·g⁻¹ at 0.5 A·g⁻¹ after 100 cycles. Therefore, the reasonable structure is of great significance for enhancing the electrochemical performances of Si-based composites.