Hierarchical Stable Enzyme Microenvironments for High‐Temperature Stability in Amine Solvents

Several methods have been proposed for capturing the CO₂ emitted into the atmosphere by human activity. To date, mainly amine‐based absorption processes are currently among the more promising systems for post‐combustion CO₂ capture. Tertiary amine solvents obviate the need for a high solvent regeneration temperature and fast absorption can be achieved with the use of carbonic anhydrase (CA), as an activator. In this study, the capacity of CA immobilization on nanoporous microparticles hierarchically structured to enhance their stability in tertiary amines is investigated. These microstructures allow for an efficient supply and presentation of substrate in the non‐aqueous solvent to the enzyme catalytic center and the particles' large size is attractive to make separation and reuse facile. These hierarchically structured particles conserve 70% of their initial activity after 30 d at 50 °C in amine solvent, whereas the free enzyme shows no activity after 1 h in the same conditions. In this work, we have overcome the technical hurdle linked to the recovery of the biocatalyst after operation thereby reducing costs of the system and importantly these micro‐bioparticles have shown a remarkable increase of the thermal stability of CA in an amine‐based CO₂ sequestration solvent as determined by a para‐nitrophenyl acetate assay.     

掺染料微结构光纤荧光传感器的理论分析

针对一般光纤荧光传感器收集荧光能力不足的缺陷,设计了一种在微结构聚合物光纤的空气孔内填充掺有机染料高折射率液体的荧光传感器.使用可调节边界条件傅里叶分解法计算了这种微结构光纤的模场分布,分析了光纤结构参量和液体折射率对荧光捕获分数的影响,结果表明,使用小纤芯半径和高于纤芯折射率的液体可以增强激发光的吸收效率,增大荧光捕获分数,提高光纤荧光传感器的灵敏度.     

K_xFe_yO_z对煤化学链催化燃烧性能影响研究

以廉价的钙铝水泥作为载氧体制备过程的载体,并以机械混合-挤压成型造粒法制备了基于Fe2O3为载氧体活性相、钙铝水泥为载体的新型载氧体。在单流化床反应器上研究了钙铝水泥添加比例以及钾添加剂对合成载氧体的化学链燃烧性能的影响。研究结果表明,合成载氧体中载体以Ca2Al2SiO7形式存在,钾的添加显著提高了煤气化反应速率以及煤转化速率,钾在稳定相中以K2Fe22O34存在。K2Fe22O34在煤化学链燃烧过程的催化性能体现在其作为储钾相与KFeO2相的形态转变过程中。     

基于多点动态捕捉的机器人关节位移与几何参数标定

机器人关节位移及几何参数误差是导致位姿出现误差的主要原因,对二者进行高精度标定可提高机器人的绝对精度．传统标定方法的精度受机器人位姿的影响,且需多次实验．本文提出一种基于多点动态捕捉测量的标定方法,可通过单次实验,同时标定串联机器人的关节位移和几何参数．首先基于多点动捕测量获取机器人各连杆上靶标点的3D坐标,结合罗德里格斯变换实现关节位移的求解．其次结合机器人运动学模型和坐标转换关系,实现几何参数误差小量的标定．对方程线性化处理以提高计算效率,并用最小二乘法降低噪声对结果的影响．最后通过对6自由度串联机器人进行仿真,验证了该标定方法的可行性．     

Ab Initio Study of the Adsorption of CO2 on Functionalized Benzenes

The interaction of carbon dioxide with a series of functionalized aromatic molecules was studied by using quantum mechanical methods (MP2), to examine the effect of the substituent on the adsorption of CO₂. Several different initial configurations of CO₂ were taken into account for each functionalized benzene to locate the energetically most favorable configuration. To get a better estimation of the binding energies, we applied an extrapolation scheme to approach the complete basis set. CH₂N₃‐, COOH‐, and SO₃H‐functionalized benzenes were found to have the strongest interaction with CO₂, and the corresponding binding energies were calculated to be ?3.62, ?3.65, and ?4.3 kcal mol^?1, respectively. Electrostatic potential maps of the functionalized benzenes and electron redistribution density plots of the complexes were also created to get a better insight into the nature of the interaction of CO₂ with the functionalized benzenes. The functional groups that were examined can be potentially incorporated in organic bridging molecules that connect the inorganic corners in MOF.     

Pressure Swing Adsorption Technologies for Carbon Dioxide Capture

The principles of pressure swing adsorption (PSA) for carbon dioxide capture are reviewed. Previous work on PSA, relevant modeling and experimental investigation for specifically carbon dioxide separation are also presented and significant findings highlighted. Simple rules for PSA process design based on analysis of the inherent properties of adsorbate-adsorbent systems encompassing equilibrium isotherm, adsorption kinetics, shape of breakthrough curves, screening and selection of adsorbent, bed porosity, adsorption time, purge to feed ratio, residence time, pressure equalization and rinse steps are provided to promote better understanding of the technology so that it gains wider acceptance in the future to address the global environmental concern, particularly in the removal of carbon dioxide as a greenhouse gas.     

Recent Advances of Porous Solids for Ultradilute CO2 Capture

The urgency of dealing with global climate change caused by greenhouse gas(GHG) emissions is increasing as the carbon dioxide(CO₂) concentration in the atmosphere has reached a record high value of 416 ppm(parts per million). Technologies that remove CO₂ from the surrounding air(direct air capture, DAC) could result in negative carbon emissions, and thus attracts increasing attention. The steady technical progress in adsorption-based CO₂ separation greatly advanced the DAC, which largely relies on advanced sorbent materials. This review focuses on the latest development of porous solids for air capture; first discussed the main types of sorbents for air capture, which include porous carbons, zeolites, silica materials, and metal-organic frameworks(MOFs), particularly their modified counterparts. Then, we evaluated their performances, including uptake and selectivity under dry and humid CO₂ streams for practical DAC application. Finally, a brief outlook on remaining challenges and potential directions for future DAC development is given.     

Electron Capture Gas Chromatography of Tertiary Amines After a Demethylation Reaction to Secondary Amines

Abstract

A gas chromatographic method for the determination of tertiary amines in micro- and nanogram amounts is presented. The tertiary amine is reacted with ethyl chloroformate to form a urethan, which is cleaved to a secondary amine. This is transformed to heptafluoro-butyramide, which makes quantitative determination with electron capture detection possible. The yields of the secondary amines for two tertiary amines were 60 and 75%. By use of internal standard technique in the entire reaction recoveries of 97.6 ± 2.2% at the 100 μg level and 100 ± 4% at the 200 ng level were obtained.     

Electron Capture Gas Chromatography of Nitrazepam in Human Plasma as Methyl Derivative

Abstract

A method for quantitative determination of nitrazepam in human plasma in the range 5 - 100 ng/ml is presented.

Nitrazepam is extracted with benzene from plasma samples of 0.5 ml, methylated with methyl iodide and determined gas chromatographically with an electron capture detector of ⁶³Ni-type.

Acid dissociation constants of nitrazepam are determined and the partition properties studied with benzene, methylene chloride and diethyl ether as organic phases.

The selectivity of the method with respect to the metabolites has been thoroughly studied.