Electrochemical Determination of Salivary N-Acetylneuraminic Acid by Miniaturized Capillary Electrophoresis Coupled with Sample Stacking

Due to their important biological role as markers for different pathologies, sialic acid （SA） analyses are important for clinical research. In this work, a miniaturized capillary electrophoresis with amperometrie detection （mini-CE-AD） was developed for the determination of N-aeetylneuraminic acid （NANA）, which is the most widespread form of SAs. NANA was first oxidized by periodic acid in an acidic solution, and then the oxidation product β-formyl pyruvic acid was derivatized with electroactive 2-thiobarbituric acid （TBA） to form an electroactive NANA-TBA adduct, which could be readily determined by mini-CE-AD. The limit of detection （LOD） of NANA-TBA could achieve 0.50 μg/mL （1.6 μmol·L-1, S/N=3） based on an online enrichment approach of moving chemical reaction boundary. The proposed method was successfully applied to the analysis of NANA in human saliva, and the recoveries were in the range of 91.8%-109% with RSDs of 1.8%-3.9%. Due to its simple design and construction, low cost and portability, the mini-CE-AD device will possess more practicability in more field work as an alternative to conventional and microchip CE approaches.

STACKING SEQUENCE OPTIMIZA-TION OF LAMINATED COMPOSITE CYLINDER SHELL FOR MAXIMAL BUCKLING LOAD

A new optimization method for the optimization of stacking of composite glass fiber laminates is developed. The fiber orientation and angle of the layers of the cylindrical shells are sought considering the buckling load. The proposed optimization algorithm applies both finite element analysis and the mode-pursuing sampling （MPS）method. The algorithms suggest the optimal stacking sequence for achieving the maximal buckling load. The procedure is implemented by integrating ANSYS and MATLAB. The stacking sequence designing for the symmetric angle-ply three-layered and five-layered composite cylinder shells is presented to illustrate the optimization process, respectively. Compared with the genetic algorithms, the proposed optimization method is much faster and efficient for composite staking sequence plan.

Investigation on the dioxin emissions from electric arc furnace in Taiwan

In this study,the formation mechanism and removal efficiency of polychlorinated dibenzo-p-dioxins, dibenzofurans（PCDD/Fs） achieved with bag filter（BF） in an electric arc furnace（EAF） in Taiwan is evaluated via intensive stack sampling and analysis.The results indicate that the PCDD/F concentration measured in the stack gas of the EAF investigated was 0.16 ng I-TEQ/m1,which was significantly lower than the PCDD/F emission limit（0.5 ng I-TEQ/m;） set for existing EAFs in Taiwan.Due to the low operating temperature（<60℃） of the BF adopted by the EAF investigated,76%of total toxicity PCDD/Fs could be removed from the flue gas stream. In addition,the partitioning of PCDD/Fs between vapor and solid phase at different locations in EAF did not change significantly,while a reduction of solid-phase PCDD/Fs was observed at the outlet of BF.As the chlorination level of PCDD/Fs congener increases,the vapor pressure of PCDD/F congener decreases,resulting in the increase of PCDD/Fs existing in solid phase.Hence,the removal efficiencies of highly chlorinated congeners were significantly higher than that of lowly chlorinated congeners.PCDFs accounted for more than 85%of the TEQ in flue gas of the EAF investigated,among them 2,3,4,7,8-PeCDF（> 43%） was of the highest contribution.Overall,2,3,7,8-TCDD,2,3,7,8-TCDF and 2,3,4,7,8-PeCDF can serve as the unique congeners in the flue gas of the stainless steel EAF process.