超疏水网状结构对水中气泡的转移作用

通过一步浸泡法制得了超疏水网状结构. 采用环境扫描电镜(ESEM)、X光电子能谱(XPS)和傅里叶变换红外光谱(FTIR)分别对超疏水网状结构的微观形貌和化学组成进行了表征, 结果表明, 超疏水的网状结构是由连续排列的类菊花状结构堆积而成的, 组成花瓣的微簇是具有层状结构的Cu[CH3(CH2)12COO]2. 借助高速照相机研究了超疏水网状结构表面与水中气泡的相互作用行为规律, 发现该超疏水网状结构对水中气泡产生转移作用, 而亲水的网状结构则不具备该特性.     

单压吸收式制冷机中气泡泵稳态工作特性研究

搭建可视化的气泡泵性能实验系统,以常压饱和水为工质,对单压吸收式制冷机中气泡泵的稳态工作过程进行实验研究,就加热功率和沉浸比对气泡泵提升性能的影响进行了分析。实验结果表明,相同沉浸比下,液体的提升量随着加热功率增加而增加,但增加的速率却随加热功率的增加而减缓;较大的沉浸比有利于降低启动加热功率,提高气泡泵的效率;分析结果对气泡泵的优化设计提供了实验依据,对单压吸收式制冷机性能的提高具有重要意义。     

Direct observation of frits and dynamic air bubble formation in capillary electrochromatography using confocal fluorescence microscopy

Confocal fluorescence microscopy has been used to study the capillary electrochromatography (CEC) frits and dynamic air bubble formation under real chromatographic conditions. Confocal fluorescence microscopy provides a nondestructive way to view the three-dimensional structure of the frits with high spatial resolution. Frits prepared with four different procedures were studied: (1) sintering bare silica beads with sodium silicate; (2) sintering bare silica beads wetted with water; (3) sintering C18 beads wetted with water; and (4) sintering C18 beads wetted with water and then surfaced-recovered with C18. Frits prepared with sintering silicate-wetted beads have a high degree of heterogeneity, while the other three types of frits have similar, more homogeneous packing structures. Confocal fluorescence microscopy also provides sufficient temporal resolution for in situ observation of the dynamic processes in air bubble formation. In this study, air bubble formation is imaged during the reorganization process of the packing bed and is shown to occur close to the border between the packing bed and the outlet frit. Confocal fluorescence microscopy opens a new avenue in studying dynamic processes in situ in CEC separations.     

Indirect Determination of CTMAB with Sodium Chloride and Ammonium Thiocyanate by Floatation and Separation of Zinc

Cetyl-trimethylammoniumbromide(CTMAB)isaveryusefulcationicsurfactant,sothestudyondeterminationofCTMABassumesgreatimportance.AsmallamountofCTMABisgenerallydeterminedbyspectrophotometrybasingCTMABcombineswithtriazidetoformcoloredbinaryion-associationcomplex1-3.However,thosemethodsofdeterminationofCTMABhavedisadvantagesofsmalllinearrange,needofspecialreagent,determinationinbaseenvironment,etc.Inthispaper,indirectdeterminationofCTMABwithNaClandNH4SCNbyfloatationandseparationofZn(II…     

Vapor–liquid equilibria of selected binary mixtures formed by 2-methylpyrazine at 94.7 kPa

Vapor–liquid equilibria at 94.7?kPa, over the entire composition range are obtained for the binary mixtures formed by 2-methylpyrazine with 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, trichloroethylene, tetrachloroethylene, N,N-dimethylformamide and N,N-dimethylacetamide. A Swietoslawski type ebulliometer is used to measure the bubble point temperatures necessary to determine the vapor–liquid equilibria. The Wilson equation is used to represent measured liquid phase composition versus temperature data.     

A Simple Method for Reliable Estimation of the Bubble Energy in the Underwater Explosion

The bubble energy is the main part of the chemical energy of the explosive that is formed upon the propagation of a shock wave through the water for the underwater explosion. A simple method is introduced for reliable prediction of the bubble energy of composite explosives containing aluminum (Al) and/or ammonium perchlorate (AP). It is shown that the bubble energy of composite Al/AP explosives depends on the number of moles of chlorine, carbon, and Al atoms. Experimental data of 56 composite Al/AP explosives are used to construct and test the novel model of the bubble energy. Statistical parameters of the new model, in external validation containing 35 composite Al/AP explosives as the training set, have the values 0.43 and 1.15 MJ · kg^–1 for the root mean squared error (RMSE) and maximum of errors (Max Error) of the new model, respectively. The values of RMSE and Max Error for 21 composite Al/AP explosives as test set are also 0.60 and 2.22 MJ · kg^–1, respectively. Cross validations of the new method corresponding to the coefficients of determination for leave‐one‐out (Q²_LOO) and the fivefold cross validation (Q²_5CV) are 0.8573 and 0.8403, respectively, which confirms goodness‐of‐fit, goodness‐of‐prediction, accuracy and precision of the novel model. It is shown that the novel correlation can be applied for pure and composite explosives, which do not contain Al/AP.     

Electrochemistry of nanobubbles

Gas bubble formation is a common phenomenon in numerous electrochemical processes, such as water splitting, chloralkaline process, and fuel cells. Many efforts have been made to understand the behaviors of microsized or larger gas bubbles in electrochemical systems in the past few decades. It was not until recent years that the electrochemistry of nanosized gas bubbles (nanobubbles) has begun receiving attention. In this short review, we summarize recent advances in the field of electrochemistry of nanobubbles, ranging from new fundamental understandings of nanobubble behaviors to the development of novel bubble-based applications inspired by the basic research of nanobubble electrochemistry.     

气浮溶剂浮选光度法测定食品中痕量SO32-的研究

提出了碘溴化十六烷基三甲胺缔合体系溶剂浮选褪色光度法测定SO2-3 的新方法,方法的摩尔吸光系数ε365=3.0×105L·mol-1·cm-1,最大吸收波长为365 nm,测定5.0μg/50 mLSO2-3 6次,RSD为1.8%,线性范围为0~30μg/50 mL,方法应用于食品中SO2-3 的测定。     

Optimization of L-Lactic acid production from glucose by Rhizopus oryzae ATCC 52311

The effect of nutrients on L(+)-lactic acid production from glucose was investigated using Rhizopus oryzae ATCC 523 11. From the shake-flask experiments, the optimal medium composition was defined for improved lactic-acid production. In order to enhance lactic-acid production rate and product yield, controlled aeration in a bubble column was conducted under optimal conditions. Results showed a maximum lactic-acid production rate of 2.58 g/L/h was obtained with an initial glucose concentration of 94 g/L. Finallactic-acid concentration of 83 g/L was achieved after 32 h of fermentation with a weight of 0.88 glactic acid/g glucose consumed.     

Mixing characteristics of a bubble mixing microfluidic chip for genomic DNA extraction based on magnetophoresis: CFD simulation and experiment

Mixing a small amount of magnetic beads and regents with large volume samples evenly in microcavities of a microfluidic chip is always the key step for the application of microfluidic technology in the field of magnetophoresis analysis. This article proposes a microfluidic chip for DNA extraction by magnetophoresis, which relies on bubble rising to generate turbulence and microvortices of various sizes to mix magnetic beads with samples uniformly. The construction and working principle of the microfluidic chip are introduced. CFD simulations are conducted when magnetic beads and samples are irritated by the generation of gas bubbles with the variation of supply pressures. The whole mixing process in the microfluidic chip is observed through a high-speed camera and a microfluidic system when the gas bubbles are generated continuously. The influence of supply pressure on the mixing characteristics of the microfluidic chip is investigated and discussed with both simulation and experiments. Compared with magnetic mixing, bubble mixing can avoid the magnetic beads gather phenomenon caused by magnetic forces and provide a rapid and high efficient solution to realize mixing small amount of regents in large volume samples in a certain order without complex moving structures and operations in a chip. Two applications of mixing with the proposed microfluidic chip are also carried out and discussed.