g-C3N4/Bi2MoO6复合光催化剂的制备及性能研究

结合热缩聚法和水热法制备了g-C₃N₄/Bi₂MoO₆复合光催化剂,利用X射线衍射（XRD）、傅里叶红外光谱（FT-IR）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、氮气吸附-脱附曲线、紫外-可见漫反射光谱（UV-Vis DRS）、光致发光光谱（PL）等分析测试技术对材料的结构和性能进行了表征,研究了材料光催化降解罗丹明B（RhB）的效果。结果表明,与纯Bi₂MoO₆相比,g-C₃N₄/Bi₂MoO₆复合材料提高了对可见光的吸收能力,减小了带隙宽度,在可见光激发下提高了降解RhB的光催化活性。其中,5% g-C₃N₄/Bi₂MoO₆复合材料对RhB的降解率最高,在可见光照射180 min对RhB的降解率为93%;而同样条件下Bi₂MoO₆对RhB的降解率为58%。重复性实验表明,复合材料在RhB光降解过程中是稳定的,具有较好的应用潜力。     

酶催化制备吡咯啉-5-羧酸和哌啶-6-羧酸的工艺

吡咯啉-5-羧酸(P5C)、哌啶-6-羧酸(P6C)是一类同代谢反应和疾病诊疗密切相关的环形亚胺化合物,在机体内氨基酸代谢中发挥重要作用。本研究利用Thermomicrobium roseum肌氨酸氧化酶对-C-N-键的催化能力建立了一种酶法制备工艺并进行了条件优化。通过薄层层析(TLC)、液质联用(LC-MS)和1H-NMR核磁共振鉴别出化合物结构,并建立了含量测定方法。单因素实验分析反应温度、pH和底物浓度对产量的影响,并通过响应面得到P5C最佳反应条件：温度为79.33℃、pH为8.54、底物浓度为112.82 mmol/L,P6C最佳反应条件：温度80.19℃、pH为8.31、底物浓度83.58 mmol/L。在此条件下反应30 min,P5C和P6C的产量分别为340.15±9.12, 450.87±8.54 mg/L。反应48 h后,转化率分别达到81.94%和99.99%。研究结果为酶法制备P5C和P6C奠定了理论基础,为吡咯啉、哌啶类化合物的合成提供了新的思路。     

Molecular level understanding of CO2 capture in ionic liquid/polyimide composite membrane

Ionic liquid(IL)/polyimide(PI)composite membranes demonstrate promise for use in CO₂separation applications.However,few studies have focused on the microscopic mechanism of CO₂in these composite systems,which is important information for designing new membranes.In this work,a series of systems of CO₂in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide composited with 4,4-(hexafluoroisopropylidene)diphthalic anhydride(6FDA)-based PI,6FDA-2,3,5,6-tetramethyl-1,4-phenylene-diamine,at different IL concentrations were investigated by all-atom molecular dynamics simulation.The formation of IL regions in PI was found,and the IL regions gradually became continuous channels with increasing IL concentrations.The analysis of the radial distribution functions and hydrogen bond numbers demonstrated that PI had a stronger interaction with cations than anions.However,the hydrogen bonds among PI chains were destroyed by the addition of IL,which was favorable for transporting CO₂.Furthermore,the self-diffusion coefficient and free energy barrier suggested that the diffusion coefficient of CO₂decreased with increasing IL concentrations up to 35 wt-%due to the decrease of the fractional free volume of the composite membrane.However,the CO₂selfdiffusion coefficients increased when the IL contents were higher than 35 wt-%,which was attributed to the formation of continuous IL domain that benefitted the transportation of CO₂.     

An Investigation into the Effect of Normal Load Frequency on Fretting Fatigue Behavior of Al7075-T6

Most previous studies on fretting fatigue have been accomplished under constant normal loading and less attention has been paid to cyclic normal loading. An innovative test apparatus was specially designed and manufactured for fretting fatigue tests under cyclic loading in this work and the fretting fatigue behavior of Al7075-T6 was investigated at different normal load frequencies. A finite element model was developed to study the effect of normal load frequency on the contact stress distribution. It was found that the cyclic normal load has a more damaging effect on fretting fatigue life compared to constant normal load, particularly at lower frequencies. The results showed that at the normal load frequency of f = 1 Hz, fatigue life decreased by 52% in the high cycle fatigue regime and 28% in the low cycle fatigue regime. The experimental results also indicated that at the normal load frequency of 80 Hz, the fretting fatigue life converged to its corresponding life under constant normal load condition. The fracture surface and the fretting area of the specimens were examined using both optical and scanning electron microscopy (SEM). The experimental observations showed that the dominant partial slip condition with a wider slip region compared to constant normal loading, severe delamination, and higher oxidation rate due to the normal load release at each cycle, are the most important reasons for significant reductions in fretting fatigue life, under cyclic normal loading, especially for low normal load frequencies.     

新型滤布的设计与织造

由聚酯和聚酰胺6两种原料的单丝经过织造、热定形、接头加工而成的滤布,具有抗拉强度大、耐曲折性好、耐酸碱、耐高温、滤水性好、质轻、使用方便等特点。以具体产品为例,阐述了生产该品种时原材料的选择、织物结构与工艺的设计及产品的技术参数。