Advanced Materials Research Vols. 518-523

Abstract: This paper deals with dynamical behaviors of Atomic Force Microscope in the different excitation frequency. By using Poincare maps, phase trajectory, Lyapunov exponent, bifurcation diagram, the dynamical behaviors are identified based on the numerical solutions of the governing equations. Bifurcation diagrams are presented in the case that the excitation amplitude increases while other parameters are fixed. Numerical simulations indicate that periodic and chaotic motions occur in the system. At the same, when chaotic motions occur, the excitation amplitude decrease as the excitation frequency increases.

Abstract: As the pulp consistency system has a big lag behind with uncertain model, the precise control of the pulp consistency could be achieved by making use of the respective advantages of variable domain fuzzy control method and the PID control method based on PSO, and shifting between these two controllers by fuzzy soft handoff switch.

Abstract: Pyrolysis and kinetic analysis of Xanthoceras Sorbifolia polysaccharide were evaluated using the TG-DTG/DTA method. The results indicated that its mass loss occured in three-step process . The first step could be attributed to the expulsion of water of crystallization at 25 - 176 °C. The second step corresponded to the large scale degradation of X. Sorbifolia polysaccharide in the temperature range of 179 - 661 °C. The final step was slow degradation of residues. Heating rate had significant effects on the pyrolysis of X. Sorbifolia polysaccharide and nitrogen could improve its stability. A close value of activation energy E of the thermal degradation process has been obtained by FWO, KAS and Popescu methods. The possible kinetic model was estimated to be Jander 5 (g(α)=[1-(1-α)^1/3]^1/2.

Abstract: Triammonium citrate was manufactured by using neutralization of citric acid solution with liquid ammonia directly. Compared with conventional route using ammonium bicarbonate or aqueous ammonia as neutralizer, the method has advantages of simple technology process, 100% raw materials utilization ratio and totally zero emission during mass production；while the raw materials utilization ratio was only 22.8% and 48.6% for using ammonium bicarbonate or aqueous ammonia as neutralizer under the same conditions. Furthermore, the proposed green route to production of triammonium citrate will save at least 813.3 kJ and 948.4 kJ of energy for manufacturing each kilogram of product than using NH4HCO3 and NH3•H2O (25%) as neutralizer, respectively. Introduction

Abstract: Low temperature and low turbidity surface water is difficult to be treated using the traditional water treatment process, especially microamount organic matter and odor compounds in the water is hardly to be removed. The aim of this paper was to study the removal effects of treating reservoir water derived from Yellow River by combination processes of KMnO₄ pre-oxidation and flotation-sedimentation tank. The results showed that the best dosage of KMnO₄ was 0.3mg/L and removal efficiency of COD_Mn, UV₂₅₄ and turbidity after KMnO₄ pre-oxidation was 20.52%, 20.17% and 13.88%, especially. The combination processes have the advantage of treating the surface water at low temperature and low turbidity

Abstract: In this study, benzaldehyde was reacted with benzoin condensation, oxidation and cyclization reaction to product phenytoin sodium under the supersonic wave radiation. In the condensation reaction, non-toxic vitamin B1 was used as a reactor instead of highly toxic cyanide on pH=9 at 70 oC. After that, FeCl3 • 6H2O was used as oxidant instead of concentrated nitric acid under the mild conditions. The results were that the yield of phenytoin sodium was up to 56.8%. There were many advantages in this improved synthesis method such as shorter reaction time, higher product purity, lower environmental pollution and higher product yield.

Abstract: In order to improve the property of pueraria lobata starch, and enlarge application fields of pueraria lobata starch, this study involved in the optimization of determining parameters in hydroxyropylation conditions and the property of acid-modified hydroxypropyl pueraria lobata starch with low substitution degree (DS).Characterizations were carried out by analyzing the spectrum of the thermograms of differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The fludity was used for characterizing the degree of acid hydrolysis. The substitution degree was measured by the spectrophotometric method. The optimized hydroxyropylation conditions were as follows: reaction temperature 40°C, reaction time 18h, amount of sodium hydroxide 1.2%, amount of anhydrous sodium sulfate 12%, respectively. The properties such as the transparency, freeze-thaw stability, blue value, swelling power, retrogradation, acid and alkali resistance of acid-modified hydroxypropyl pueraria lobata starch were compared with those of pueraria lobata starch and acid-modified pueraria lobata starch. It was shown that acid hydrolysis and hydroxyropylation increased the decomposition temperature, but reduced the enthalpy value from the thermal analysis.

Abstract: spinach contains a variety of plant pigments, high lutein content, which makes the research of spinach pigment extracting research special significance. Supercritical CO₂ fluid extraction food industry is a new extraction and isolation technique; microwave assisted extraction technology has the potential to become future food industrialization production of the leading. The UV-vis spectrophotometric analysis, parallel experimental method to determine the optimum process conditions of extracting pigment from spinach. For supercritical CO₂ extraction: ethanol (as extractant) is 250ml, extraction pressure 30MPa, extraction temperature 50°C, extraction time 1.5h. The microwave assisted extraction of ethanol as extractant, liquid ratio is 1:20, extraction time1.5h, extraction temperature of 40 °C. The comparison of two methods: microwave extraction is energy saving and high efficiency, and supercritical fluid extraction has safety and environmental protection, therefore, the two methods are worth to advocate and promote.

Abstract: ceramic formula; genetic algorithm; the simplex method; particle swarm optimization Abstract. The composition of ceramic materials determines its performance, so ceramic formula determines the performance of the product. The factors, such as supply of local raw materials, chemical composition, and raw material price, determine the formula. Selecting raw materials from a variety of raw materials which are consistent with the target formula and the percentage content of the chemical composition is a very important job. The chemical composition in the ceramic material is various, and the traditional method is to calculate the formula by hand. The workload is very heavy, and the results are often not accurate, and don’t meet actual requirements. By minimizing the deviation of chemical composition and mineral ingredients, the chemical and comprehensive formula optimization models of ceramic preform body were constructed. Several typical optimization algorithms were used to construct the formula model, such as particle swarm optimization, genetic algorithms and Nelder-Mead simplex method. The experimental results were presented and compared and it concluded that the particle swarm optimization algorithm is superior to the other optimization algorithms.

Abstract: This paper describes the chiral synthesis of R-2,6-dimethyl-4-(3-nitro phenyl)-1,4- dihydro-pyridine-3,5-dicarboxylic acid 3-ethyl ester 5-methyl ester (R-Nitrendipine) using chiral phase transfer catalyst. The structure of the obtained nitrendipine crystals was determined with single crystal X-ray diffraction. The crystal is monoclinic, with the space group of P21/c and unit cell constants of a=8.8577(15), b=15.581(3), c=12.999(2)Å, β=92.458(4)°, V=1792.3(5)Å3, Z=4, Dc =1.335g/cm3, F(000)=760. X-ray analysis reveals that the product is a chiral nitrendipine with R-configuration of the dihydropyridine ring. And measurement of polarimeter reveals that the synthesized nitrendipine is a chiral molecular.