Advanced Materials Research Vols. 712-715

Abstract: The erythrocytes play an important role in delivering oxygen and carbon dioxide in the human body. They are generally believed to be highly deformable and are able to squeeze through small capillaries. The elastic rigidity of the cell is associated to the change in free energy caused by both the stretch and the bending of the erythrocyte membrane. If the curvature of a shell is changed by deformation, the bending stiffness must be considered. However, researchers usually focus on the stretch of the cell membrane while analyzing the experimental data. In this article, mechanical models were proposed to study the erythrocytes deformation during optical tweezers stretching and micropipette aspiration. The effect of membrane bending stiffness on the cells deformability was concluded using finite element modeling and simulation.

Abstract: Matrix-assisted laser desorption/ionization time-off light mass spectrometry (MALDI-TOF MS) is increasingly used as a microbial diagnostic method for species identification of pathogens. However, MALDI-TOF MS identification of food bacteria was seldom reported. Ten strains isolated from different pickled vegetables were rapid identified by MALDI-TOF MS. The results of MALDI-TOF MS were confirmed by 16S rDNA sequencing method. Different score values in MALDI-TOF MS revealed nine Leuconostoc mesenteroides and one Staphylococcus. Identification success at the species and genus levels was 90% (9/10) and 100% (10/10), respectively.16S rDNA sequencing results showed that nine stains were identified as Leuconostoc mesenteroides and one was Staphylococcus saprophyticus. Results obtained demonstrate that MALDI-TOFMS is a promising method for discriminating and identifying food bacteria.

Abstract: The content of heavy metals Cr, Cu, Zn, As in 15 ponds sediment of suburban district were determined in Suzhou City. The results showed that the contents, except for Cr, all above geochemical background values of Anhui Province. Meanwhile, the index of geoaccumulation and the Lars Hakansons method were used to assess pollution level and potential ecological risk of the heavy metals. The assessment results revealed that Cu was light pollution, and the others were non-pollution. And heavy metal potential ecological indexes from 36.62 to 75.85 were less than 150, which illustrated the potential ecological risk small.

Abstract: Micro-molecular dextran was prepared in sub-critical water/CO₂ by hydrolysis of dextran20. The obtained products were mainly characterized by FT-IR and GPC. Furthermore, the reaction temperature, reaction time, reaction pressure, solid-liquid radio and stirring speed were systematically investigated during the work. The optimum reaction conditions are as follows: the reaction temperature was 160°C; the reaction time was 60 min; the reaction pressure was 2.5MPa; the solid-liquid ratio was 0.6 and the stirring speed was 300r/min.

Abstract: The content of total lipids in Pacific white shrimp head was higher than those find in other shrimps. A process to extract lipids from Pacific white shrimp waste (head) was developed. Supercritical fluid extraction was used and the effects of temperature, pressure, CO₂ flow rate and extraction time on extraction yield and composition of the fatty acids were investigated. The extraction yield had little dependence on pressure, temperature and CO₂ flow rate. However, the pressure and temperature conditions affected the composition of the fatty acids. Addition of entrainer can increase the extraction yield significantly (P<0.01), the maximum of the extraction yield was 80.9% with 8% ethanol at 30 Mpa, 45°C and 1 L/min.

Abstract: Gene vector system is the key to realize gene transduction and therapy. A proper gene vector can introduce the target gene into cells securely, efficiently, controllably and easily, and achieve purposes of gene transfection and disease treatment after its expression. ε-polylysine (ε-PL),which is rich in cationic and has high penetrability through biological membrane,can be applied in DNA carrier. In this study, we presented a novel approach for preparing ε-polylysine modified silica nanoparticles and combinating them with plasmid DNA.

Abstract: Firstly, two biosurfactant-producing bacteria named 1# and 2# was selected from 7 strains. Secondly, their growth and metabolism laws that the quantity of metabolic products would reach the highest and the value of surface tension would bottom out in the stationary phase of growth was found in the culture flask. Thirdly, the optimal condition for fermenting was chose by the orthogonal test which was used to study the effect of constituent of fermentation medium, culturing temperature and rotation speed of shaking table on the capability of metabolizing biosurfactants. Finally, compared the interfacial tension of strain 1# with that of strain 2# at the optimum conditions, strains 1# was chose for industrial fermentation.

Abstract: For understanding the temporal variation of nitrogen and phosphorus concentrations in Huihe River, Suzhou, the observed data (including NH₄⁺-N、 TN、TP, the temple and quantity of the water) from 2007 to 2010 were analyzed by statistical analysis including correlation, cluster and factor analysis. The results imply that the variations of concentrations of NH₄⁺-N, TN and TP in Huihe River were significant, their concentrations are 0.05-4.22mg/L, 0.11-15.14mg/L and 0.01-1.41mg/L, respectively. Correlation and factor analysis suggest that NH₄⁺-N、TN and TP are well correlated with water temperature, whereas there is no significant between them and water quantity. Comparative study and cluster analysis, as well as factor analysis imply that the temporal variations of nitrogen and phosphorus concentrations in Huihe River are significant, and coincide with the seasonal variation of climatic variation of the study area. The results show that either dredging project or climate factors (seasonal changes) had dramatically affected the pollution of NH₄⁺-N, TN and TP. Moreover, the study also confirmed that NH₄⁺-N, TN pollution is mainly anthropogenic, different with TP pollution, who is more likely to be controlled by natural factors.

Abstract: Corncob xylitol residue was soaked with H₃PO₄ for 16h and carbonized in microwave for 9min to obtain activated carbon. Methylene blue and iodine adsorption values were determined and were 119.92mg/g and 839.47mg/g, respectively. The adsorption property on Cr⁶⁺ was determined and the proper adsorption condition was pH2, 30min, 80°C. The maximum Cr adsorption capacity was 50mg/g.

Abstract: Corncob hydrolysis residue was milled into powder and the fraction between 100-120 mesh was used as adsorbent for Cr (VI) ion. Results showed that the optimum adsorbing condition was: pH 1-2, 120 minutes, 80°C. Effects of particle size on adsorbing ability of corncob residue were alse investigated. Particles with smaller diameter had stronger adsorbing capacity and the proper particle size was 100-120mesh, the adsorbing capacity of corncob hydrolysis residue was 10-17mg/g.