Relationship of nanostructure and thermo-chemical response/thermal ablation of carbon aerogels

In this work, the interfacial mass balance relations combined with the non-parametric kinetic (NPK) analysis results were used for evaluating the thermo-chemical ablation process and oxidation mechanism of carbon aerogels with various porous structure. It was found that the two-parameter model of Nomen–Sempereis was able to describe the kinetics of the oxidation reaction and to reveal the structure-dependent contribution of two main processes with chemical and physical nature. The porosity of the carbon aerogel, rather than the other microstructural features, was realized more effective on the rate of ablation.     

Heteroborospherene nanoclusters as high-performance nonlinear optical materials

Today, the design of new compounds with giant nonlinear optical responses is attracted to many researchers. Inspired by an interesting finding of a new class of heteroborospherenes which were formed by doping four carbon atoms in the B364- nanocluster (C4B32), we suggest the alkali metal-doped C4B32 (M@C4B32, M=Li, Na, and K) nanoclusters as high-performance nonlinear optical materials. Our results show that the alkali metal atoms have a considerable effect on the structural and electronic properties of the C4B32 nanocluster. We found that the doping alkali metal can remarkably decrease the HOMO-LUMO gap and significantly increases the first hyperpolarizability of the C4B32 nanocluster. Also, our results reveal that the first hyperpolarizability of the M@C4B32 nanoclusters can be progressively enhanced by increasing the atomic number of alkali metals. The effect of external electric fields on the nonlinear optical responses of the M@C4B32 has been systematically explored. We found that the first hyperpolarizability of the M@C4B32 compounds can be gradually increased by increasing the imposed external electric field from zero to the critical external electric field along the charge transfer direction (M→C4B32). Accordingly, this work presents an efficient strategy to improve the nonlinear optical responses of the heteroborospherenes.     

高温、高压、高应变速率动态过程晶体塑性有限元理论模型及其应用

对于高温、高压、高应变速率加载条件下的材料冲击变形行为,动态晶体塑性模型能够直接反映晶体中塑性滑移的各向异性及其对温度、压力和微观组织结构的依赖性,因而广泛应用于材料的动态冲击力学响应、微观结构演化以及动态损伤破坏的模拟。本文综述了高压冲击下动态晶体塑性有限元的理论模型,主要包括变形运动学、包含状态方程的超弹性本构模型和晶体塑性本构模型,涉及位错滑移、相变、孪生等塑性变形机制,以及层裂、绝热剪切带等动态破坏方式。     

Multivariate optimization and comparison between conventional extraction (CE) and ultrasonic-assisted extraction (UAE) of carotenoid extraction from cashew apple

Carotenoids are an essential component of cashew and can be used in pharmaceuticals, cosmetics, natural pigment, food additives, among other applications. The present work focuses on optimizing and comparing conventional and ultrasound-assisted extraction methods. Every optimization step took place with a 1:1 (w:w) mixture of yellow and red cashew apples lyophilized and ground in a cryogenic mill. A Simplex-centroid design was applied for both methods, and the solvents acetone, methanol, ethanol, and petroleum ether were evaluated. After choosing the extractor solvent, a central composite design was applied to optimize the sample mass (59–201 mg) and extraction time (6–34 min). The optimum conditions for the extractor solvent were 38% acetone, 30% ethanol, and 32% petroleum ether for CE and a mixture of 44% acetone and 56% methanol for UAE. The best experimental conditions for UAE were a sonication time of 19 min and a sample mass of 153 mg, while the CE was 23 min and 136 mg. Comparing red and yellow cashews, red cashews showed a higher carotenoid content in both methodologies. The UAE methodology was ca. 21% faster, presented a more straightforward composition of extracting solution, showed an average yield of superior carotenoid content in all samples compared to CE. Therefore, UAE has demonstrated a simple, efficient, fast, low-cost adjustment methodology and a reliable alternative for other applications involving these bioactive compounds in the studied or similar matrix.     

对称非经典阻尼系统动力响应精确解算法比较

分别采用频响函数法和复频率响应法对同一个数值算例进行了稳态响应、使用条件和范围以及误差来源分析,阐述了两种算法在工程执行过程中的特点及效率。     

加强实验教学过程管理促进实验教学目标达成

实验教学目标的达成依赖于严格的实验过程的科学管理。本文介绍了大连理工大学基础化学实验中心通过《化学实验指导手册》的编制和严格执行,培养学生的实验安全环保意识,加强对实验过程的指导。将实验各环节纳入考核范畴,目的在于着力培养学生良好的实验习惯,规范实验报告撰写和提高学生的创新思维能力,从而有效地监控和保证了实验教学质量。     

Liquid crystals alignment with PbS nanosculptured thin films

Lead sulphide (PbS) nano-sculptured thin films (nSTFs) are prepared for the first time using glancing angle deposition technique by physical vapour deposition process. An anisotropic morphology is obtained, which provides an orientational effect. Due to this anisotropic nature of PbS nSTF an attempt has been made to check its effect on the alignment of nematic liquid crystals (LCs). Two different LC devices were fabricated, that is, anti-parallel aligned or electrically-controlled birefringence and hybrid twisted nematic. It is noticed that in both types of devices, good alignment is obtained with high extinction and contrast. A significant effect of these alignments on the electro-optic properties of the LC is reported such as the threshold voltage, response time and contrast ratio.     

基于互动反馈教学系统的无机化学课堂教学改革

针对基础无机化学教学存在的普遍问题,在课堂教学中引入互动反馈教学系统。重点从课堂设计、课堂互动模式、课后测试、课程分析总结等4个方面介绍了课堂互动反馈教学系统的具体应用;互动教学模式对无机化学教学的促进作用显著,整个学期平均到课出勤率达到99%,95%以上的学生认为这种互动教学方式能活跃课堂气氛,激发学习兴趣,愿意接受基于课堂投票表决器构建的互动教学模式。     

Investigation and optimization of the recovery of coal fines using oil agglomeration process: Use of waste oils from different sectors

The high cost of the bridging liquid subdues the implementation and commercialization of oil agglomeration process. To overcome this problem, waste oils from different sectors were used in this present study. The performance of the process was assessed based on the responses like ash rejection and organic matter recovery. The aim of the present study was to investigate the usage of waste oils from different sectors and to optimize and analyze the behavioral pattern showcased by different variables (pulp density, oil dosage, agglomeration time and oil type) using response surface methodology (Box-Behnken design). Experimental investigation shows that the optimum pulp density, oil dosage, agglomeration time and oil type condition obtained as 3%, 15%, 15?min and waste engine oil, respectively. At optimum condition, the % ash rejection and % organic matter recovery obtained as 63.94% and 81.8%, respectively.