聚甲基丙烯酸甲酯在纳米氧化铝表面的吸附和氢键作用

研究了聚甲基丙烯酸甲酯(PMMA)在纳米氧化铝表面的吸附行为, 采用透射红外光谱研究了吸附的PMMA中的羰基和纳米氧化铝表面羟基之间的氢键作用. 结果表明, PMMA在纳米氧化铝表面的吸附曲线为典型的Langmuir曲线, 饱和吸附值为1.2 mg/m2, 受氢键作用影响, 键合羰基在红外光谱中的吸收峰向低波数方向移动. 根据计算, 羰基的最大键合值(即含键合羰基的甲基丙烯酸甲酯单元的总质量)为0.36 mg/m2, 其余为自由羰基. 随着吸附量的增加, 羰基的键合比例逐渐降低. 吸附达到饱和时, 羰基键合比例为0.30, 说明PMMA主要以平铺的方式覆盖在纳米氧化铝的表面.     

Rain Height in Relation to 0°C Isotherm Height Over Some Indian Tropical Locations and Rain Attenuation for an Indian South Coastal Station for Microwave and Millimeter Wave Communication Systems

There is a dearth of results on rain height over Indian tropical stations.The results on rain height in relation to 0°C isotherm height over four stations having different latitudes are presented in this paper. Four stations have been chosen in such a way that all have different latitudes and are located in different geographical regions having different local weather conditions. The seaonal variation of rain height in relation to 0°C isotherm height has been found to be appreciable over the station located in Indian east coast and Gujarat region, while seasonal variation is not significant at lower and intermediate probability levels over the stations located in Indian south-east coast and island. The prevailing local weather conditions over different stations also have been discussed. Based on observed rain heights and rain rates, the attenuation of radio wave at different frequencies lying in the range from 10 GHz to 150 GHz for different probability levels over Indian south-east coastal station have been deduced and presented in this paper.     

Molecular adsorption and growth of n-butane adlayers on Pt(1 1 1)

The molecular adsorption of n-butane and the growth of n-butane adlayers on Pt(1 1 1) was investigated using molecular beam techniques, temperature-programmed desorption (TPD) and low-energy electron diffraction (LEED). It is found that as the surface coverage of n-butane increases, structural changes occur in the adlayer at surface temperatures near 98 K that are accompanied by changes in the binding energy and mobility of the adsorbed species. The film growth process can be divided into four distinct coverage regimes. At low coverages (θ<0.14 ML, where 1 ML is defined as one butane molecule per Pt atom) a disordered monolayer forms in which the butane molecules prefer to lie parallel to the surface in order to minimize their binding energy. At coverages from 0.14 to 0.20 ML, ordered regions develop within the monolayer in which the butane molecules also lie parallel to the surface. The binding energy in the ordered phase is lower than that in the disordered phase due to repulsive intermolecular interactions. A more densely-packed ordered phase begins to form at 98 K after the low-coverage ordered phase saturates at 0.20 ML. The experimental results suggest that the n-butane molecules tilt away from the surface in the high-coverage ordered phase. Finally, a disordered second layer phase forms after the high coverage ordered phase saturates at 0.35 ML. The molecules in the second layer are very mobile at 98 K and rapidly diffuse to the edges of the beam spot. Interchange of molecules between the second layer and ordered monolayer is found to govern the net rate of second layer diffusion at surface temperatures less than 133 K. The adsorption probability of n-butane on Pt(1 1 1) continuously increases with increasing coverage, with no significant dependencies on the structure of the n-butane adlayer. This finding indicates that the long-range arrangements and molecular orientations of a mobile alkane adlayer have a negligible influence on the intrinsic adsorption dynamics, suggesting that the energy transfer processes that facilitate adsorption are highly localized.     

氢气在炭狭缝微孔内吸附的预测

通过边界的平均场近似,推导二平板狭缝孔格子理论Ono-Kondo吸附等温方程。利用格子模型特性和微观物理学理论,计算氢分子在石墨平面的最大吸附容量。比较由氢分子在石墨平面二典型聚集状态标定的Ono-Kondo方程,并用预测精度较高的方程计算了与文献相同条件下的吸附等温线。在比较了计算结果、试验结果和GCMC分子模拟结果后,对Ono-Kondo吸附等温方程的特点、理论基础作了分析,指出了方程的适用范围。     

Au/Pd(111)双金属表面催化噻吩加氢脱硫的反应机理

采用密度泛函理论（DFT）计算了Pd（111）表面含有N（N=1-4）个Au原子数目时的表面形成能,选取最优构型进一步研究了噻吩在Au/Pd（111）双金属表面的吸附模式及加氢脱硫反应过程. 结果表明：当Pd（111）表面含有1个Au原子时,其形成能最低. 在Au/Pd（111）双金属表面噻吩初始吸附于Pd-Hcp-30°位时,其构型最稳定. 在各加氢脱硫过程中,反应总体均放出热量. 对于直接脱硫机理,其所需活化能较低,但脱硫产物较难控制;对于间接脱硫机理,反应最有可能按照顺式加氢方式进行,C―S键断裂开环时所需活化能最高,是反应的限速步骤. 此外,与单一Au（111）面及Pd（111）面相比,Au/Pd（111）双金属表面限速步骤的反应能垒最低,表明AuPd双金属催化剂比Au、Pd单金属催化剂更有利于噻吩加氢脱硫反应的进行.     

竹叶提取物对铝在HCl溶液中的缓蚀作用

用不同浓度的C₂H₅OH（体积分数：20%-80%）从金竹竹叶中提取制备出竹叶缓蚀剂（简称为PSLE）,用紫外-可见（UV-Vis）光谱和傅里叶变换红外（FTIR）光谱对其进行了表征,并对总黄酮含量进行了测定. 采用失重法、动电位极化曲线、电化学阻抗谱（EIS）和扫描电子显微镜（SEM）研究PSLE在HCl 介质中对铝的缓蚀作用.采用量子化学密度泛函理论（DFT）研究了两个主要竹叶黄酮成分牡荆苷和异牡荆苷的吸附方式. 结果表明：PSLE对铝具有良好的缓蚀作用,且在铝表面的吸附符合Langmuir 吸附等温式. 缓蚀率随其浓度的增加而增大,但随温度的升高和盐酸浓度的增加而降低. 竹叶总黄酮含量和竹叶缓蚀剂的缓蚀性能有良好的相关性,初步推测竹叶缓蚀剂的有效成分主要为竹叶黄酮类化合物. PSLE为阴极抑制型缓蚀剂;EIS 在高频区呈容抗弧,在低频区呈感抗弧,添加PSLE后,阻抗值显著增大. SEM表明添加PSLE对铝的腐蚀产生了明显的抑制作用.量子化学计算结果表明,牡荆苷和异牡荆苷的吸附中心主要集中在竹叶黄酮骨架（FBS）.     

层状四水硫酸锆催化合成乙二醇单乙醚醋酸酯反应机理的理论研究

采用以量子化学ASED－MO（含原子对排斥的EHMO法）为基础的结构自动优化EHTOPT法,研究了层状四水硫酸锆催化合成乙二醇乙醚醋酸酯的反应机理;构筑了反应组分乙二醇单乙醚羟基上的氢原子通过氢 键与层状四水硫酸锆结晶水上的氧原子结合。同时,还研究了醋酸在四水硫酸锆表面形成正碳离子的结合状态,提出了相应的酯化反应机理,在此基础上推导出的动力学方程与实验结果相符。     

几种吸附树脂对五氯酚钠吸附性能的研究

研究了几种树脂对五氯酚钠的吸附能力,其中戊二醛交联的壳聚糖树脂不仅有较好的吸附效果,动态吸附容量为187.5mg/g干树脂,而且易洗脱,洗脱率高达90%以上。     

沥青基球状活性炭气相吸脱附行为研究

本文利用热重法研究了一系列沥青基球状活性炭对蒸汽及正已烷蒸汽的动态吸脱附曲线。结果表明,PSAC对苯蒸汽的吸附及再生性能优良。随吸附温度的降低、比表面积的增大、总孔容及微孔容的增大,PSAC对苯蒸汽的吸附容量增大。PSAC对正已烷的吸附速度大于对苯蒸汽的吸附速度,但其对正已烷的平衡吸附容量小于对苯蒸汽的平衡吸附容量。     

离子交换法从醋酸溶液中提取脯氨酸的研究

本文研究了脯氨酸在732,DO01,DH-8三种阳离子交换树脂上的静态吸附特性,发现732树脂的吸附容量最大,速度最快。并选用732树脂,研究了它从醋酸脯氨酸水溶液中吸附脯氨酸的动态过程。最后,以氨水为洗脱剂,考察了不同氨水浓度,洗脱速度对洗脱过程的影响。