黄檗果实精油的化学成分、抗氧化及细胞毒活性研究

采用水蒸气蒸馏法提取黄檗果实精油,利用气相色谱-质谱联用技术(GC-MS)对其成分进行分离鉴定;通过DPPH自由基清除作用和β-胡萝卜素漂白法检测精油的抗氧化活性,应用磺酰罗丹明B(SRB)比色法检测精油对人宫颈癌细胞He La、人肺癌细胞A-549和人胃癌细胞BGC-823这3种肿瘤细胞株的细胞毒活性。经GC-MS分析,从黄檗精油中共鉴定出39个成分,主要有β-蒎烯、β-氧化石竹烯、3-亚甲基-4-异丙烯基环己醇、西松烯等。精油具有一定抗氧化活性,对肿瘤细胞株A-549和BGC-823的细胞毒活性不显著,但对He La细胞具有较好的细胞毒活性。     

电解液组成对CO_2电化学还原效率的影响

为了考察电解液组成(溶剂和支持电解质)对CO_2电还原效率的影响,以金属银为工作电极,在三电极电解槽中进行了恒电位电解及循环伏安扫描实验。结果表明:相比于二甲基甲酰胺(DMF)和甲醇,用乙腈作溶剂时产物CO法拉第效率最高;强酸作为阳极液支持电解质可以降低CO_2还原过电位并提高CO部分电流密度;离子液体作为阴极液支持电解质可以全面提高CO_2还原效率。研究不同离子液体的催化行为,发现离子液体中阳离子部分对CO部分电流密度的影响比阴离子的影响更明显,进一步证实了咪唑阳离子对还原CO_2起主要催化作用。     

Structure and Microwave Dielectric Behavior of A‐Site‐Doped Sr(1−1.5x)CexTiO3 Ceramics System

The ion valence state, phase composition, microstructure, and microwave dielectric properties of Sr_(1?1.5x)Ce_xTiO₃ (x = 0.1–0.67, SCT) ceramics were systematically investigated. Sr_(1?1.5x)Ce_xTiO₃ ceramics were produced with gradual structural evolution from a cubic to a tetragonal and turned to an orthorhombic structure in the range of 0.1 ≤ x ≤ 0.67. Above a critical Ce proportion (x = 0.4), microstructural changes and normal grain growth initially occurred. On the basis of chemical analysis results, the reduction of Ti⁴⁺ ions was hastened by tetravalent ions (Ce⁴⁺). By contrast, this reduction was inhibited by trivalent ions (Ce³⁺). The observed dielectric behavior was strongly influenced by phase composition, oxygen vacancies (), and defect dipoles, namely, () and (). Temperature stable ceramics sintered at 1350°C for 3 h in air yielded an intermediate value of dielectric constant (ε_r = 40), with the smallest reported value of temperature coefficient of resonant frequency (τ_f = +0.9 ppm/°C), and quality factor (Q × f = 5699 GHz) at x = 0.6.     

多反应体系热力学中的元素组成法(Ⅱ):剩余性质、混合变化性质及超额性质之间的关系

Based on the concept of “element” and the fundamental thermodynamic principle,the relationships of the residual properties,the property changes of mixing,excess properties,fugacity coefficients and activity coefficients between the hypothetical solution of elemental species and the equilibrated solution of actual species were established.The hypothetical solution of elemental species provides a way of reducing the dimensionality of problem, simplifying the analysis and visualizing the phase behavior.     

准东煤成灰过程中钠的迁移特性及形态变化

为研究准东煤成灰过程中钠的迁移特性及形态变化,通过热重试验分析了5种准东煤的着火温度和燃烬温度,在575和815℃成灰温度下对5种准东煤进行灰化试验;重点研究了成灰温度对准东煤成灰特性的影响,采用X射线荧光光谱仪(XRF)、X射线衍射仪(XRD)、扫描电镜-能谱分析仪(SEM-EDS)等方法对成灰理化特性进行了表征,最后采用化学热力学软件Fact Sage模拟了准东木垒煤灰化过程中钠的迁移特性。结果表明,5种准东煤的着火温度均低于400℃,燃烬温度均低于500℃。575和815℃成灰物质形态与理化特性差异明显,815℃时5种准东煤成灰中钠含量相比575℃分别降低了47.67%、88.89%、62.45%、52.48%和85.78%,成灰表面钠含量分别降低了67.52%、75.70%、44.87%、63.71%和90.08%。成灰温度不仅影响煤灰中钠含量,还影响钠的赋存形态,800℃以上高温灰中出现黏结现象。最终确定5种准东煤的成灰温度为575℃,既能保证煤样成灰完全,又能最大限度减少灰化过程中碱金属钠元素的损失。     

粉煤灰的矿物学性质研究

为了拓展粉煤灰综合利用途径,提高粉煤灰产品的附加值,采用X射线衍射(XRD)分析方法,研究神华电厂粉煤灰的矿物相组成及其晶相结构。研究表明:神华电厂粉煤灰由非晶质玻璃体和晶质矿物相组成,通过结晶度模拟计算可知非晶质玻璃体含量在35%~70%,进一步分析发现其矿物相以莫来石相(7%~52%)、石英相(0~22%)为主,还包括石灰相、磁铁矿相、赤铁矿相、硬石膏相、钙长石相和钙铝黄长石相等。此外,进一步分析了燃煤组成及燃烧方式对矿物组成差异的影响,从而为了解粉煤灰的特性及其高附加值利用提供理论基础。     

Considerable Enhancement of Field Emission of SnO2 Nanowires by Post-Annealing Process in Oxygen at High Temperature

The field emission properties of SnO₂ nanowires fabricated by chemical vapor deposition with metallic catalyst-assistance were investigated. For the as-fabricated SnO₂ nanowires, the turn-on and threshold field were 4.03 and 5.4 V/μm, respectively. Considerable enhancement of field emission of SnO₂ nanowires was obtained by a post-annealing process in oxygen at high temperature. When the SnO₂ nanowires were post-annealed at 1,000 °C in oxygen, the turn-on and threshold field were decreased to 3.77 and 4.4 V/μm, respectively, and the current density was increased to 6.58 from 0.3 mA/cm² at the same applied electric field of 5.0 V/μm.     

法兰高温螺柱失效分析

通过对歧化反应器油气出口管线法兰高温螺柱的化学成分分析、硬度检测、力学性能检测、扭断断口的宏观形貌观察、扫描电镜能谱分析以及金相观察等,多方面分析了该批螺柱失效的原因,对高温法兰紧固件的选材、原材检测、复验、施工过程质量控制等环节提供帮助。     

学研互动 推进大化工实验教学的改革

我校以“工程基础-技术基础-过程综合-创新实践”为主线,以化学工程学科发展方向为立足点,建立了多层次、模块化、循序渐进的大化工实验教学体系,依托学研互动,将科研成果转化为实验项目,推动研究性学习,强化了实验教学的育人功能。     

改革化学反应工程实践教学模式，培养创新人才——大化工类人才培养创新实验区的实践与探索

本文围绕建设人才培养模式创新实验区这个主题,结合化学反应工程课程的工程应用特点,探讨了人才培养模式创新实验区对化学反应工程课程改革的要求和定位,分析了该课程实践教学存在的不足,提出了一种适用创新教育的化学反应工程实践教学模式。