Advanced Materials Research Vols. 490-495

Abstract: Organic synthesis chemistry is a very fast-growing discipline and it plays a very important role in chemistry. With the development of organic synthetic chemistry, organic synthesis device has also made greater development. At the same time, advances of organic synthesis device further promote the development of organic synthetic chemistry. This paper describes the working principle and system architecture of organic synthesis device and takes a case of di-n-butyl phthalate (DBP). At last, I foresee great prospect for organic synthesis

Abstract: Synthesis reactions were carried out by chemical vapor deposition using iron catalyst supported on aluminum hydroxide at 400 °C and 420 °C, in the presence of argon as carrier gas and acetylene as carbon source. The aluminum hydroxide support was separated by refluxing the samples in 40% NaOH solution for 2 h and 36% HCl solution for 24 h, respectively. The samples were characterized by field-emission scanning electron microscopy, energy dispersive spectroscopy, high-resolution transmission electron microscopy and X-ray diffraction. The results show that carbon nanotubes were the main products at 420 °C, while large scale high purity nano onion-like fullerenes encapsulating Fe3C, with almost uniform sizes ranging from 10-50 nm, were obtained at the low temperature of 400 °C.

Abstract: Aiming at the difficult question of qualitative analysis for welding flaws in ultrasonic testing, a novel method of flaw classification utilizing the combination of wavelet packet transform (WPT) with the layer multi-class classifier based on -SVM is presented in this paper. First, WPT is applied to extract features for ultrasonic echo-signals of welding flaws, and flaws are automatically classified by using the layer multi-class classifier based on -SVM. Then, its classification results are compared with that of several widely used multi-class SVM classification methods. To validate the method above, a series sample of butt girth welds of seamless steel tube with four types of welding flaws is made, and some experiments are performed. The results show that the proposed method is superior to other multi-class SVM classification methods in the aspects of classification accuracy, training and testing time.

Abstract: We have developed extremely high efficiency orange phosphorescent organic light-emitting diodes based on an orange phosphorescent material, employing the structure of phosphorescent dye-doped hole transporting layer to improve the power efficiency. The device shows a bright orange emission at approximately 564 nm (Commission Internationale d’Eclairage (0.49, 0.50)) and a maximum brightness of 31030 cd/m2 at a driving voltage of 7.6 V. The power efficiency of device has reached 83.56 lm/W at turn-on voltage of 2.2 V. Moreover, this power efficiency has the potential to be raised to 150 lm/W if the light outcouping can be further improved.

Abstract: The transverse dynamical behaviors of softness Euler-Bernoulli nanobeams subjected to a biggish initial axial force based on nonlocal elasticity theory are investigated in this paper. The size-dependent theory is considered and a small intrinsic length scale parameter unavailable in classical continuum mechanics is adopted into the problem model as a size parameter. The linear partial differential governing equation is derived from the Newton’s second law and the ordinary equation and its dispersion relation are gained from by the method of separation of variables. Five sets of supporting conditions are presented respectively including simply supported, fully clamped, flexible fixed ends, sliding supports ends and completely free ends. Vibration frequencies are obtained approximately and correlations between the natural frequency and the dimensionless small scale parameter are also analyzed and discussed in detail. It shows that an increase in small scale parameter and dimensionless initial axial tension causes natural frequency to increase, while an increase in the dimensionless stiffness of nanostructures causes natural frequency to decrease, or the nanostructural bending stiffness is enhanced when nonlocal effects are considered.

Abstract: After H2SO4 pretreatment, in unbleached pulps the content of metal ions Mg2+、Mn2+、Fe3+、Zn2+ and Cu2+ are reduced in varying degrees by atomic absorption spectroscopy analysis, among the ions, the maximum removal rates are Cu2+ and Mg2+. And when the added amount of H2SO4 is 1.5%, the removal result of metal ions is the best. After acid pretreatment, the pulp’s brightness has been increased about 3.8%ISO-5%ISO, the pulp’s hardness has been reduced by 0.7%-1.0%, the pulp’s viscosity has been kept well. Besides, when the added dosage of H2SO4 is 1.0%, the increasing of whiteness and the decreasing of hardness are the greatest. Through the contrast research of photocatalysis bleaching to the two pulps of before and after acid pretreatment, the results has been found that the brightness of bleached pulp been decreased about 2.3%ISO-3.5%ISO, and the decreasing rates of hardness and viscosity respectively are almost the same after H2SO4 pretreatment.

Abstract: In this paper, a physical model of semisolid rheo-casting process by cooling sloping plate is established, and the features and parameters of this process are analyzed. The calculation results show that there exists lamellar flow and turbulent flow on the sloping plate surface commonly. The critical transfer distance from lamellar flow to turbulent flow decreases with the increment of the initial flow velocity gradually. The critical transfer distance decreases with the increment of the sloping angle slowly. The effect of the sloping angle on the critical transfer distance is relatively not obvious.

Abstract: The mechanical behaviors near interface crack tip for mode I of double dissimilar orthotropic composites are studied. By translating governing equations into generalized biharmonic equations, the stress functions containing two stress singularity exponents are found with the help of a complex function method. Based on the boundary conditions, two systems of non-homogeneous linear equations are obtained. Through solving these systems two real stress singularity exponents are determined under appropriate condition of bimaterial engineering parameters. By the uniqueness theorem of limit,both the theoretical formulae of stress intensity factors and analytic solutions of stress field and displacement field near interface crack tip are deduced.

Abstract: A detailed theoretical study of the optical properties of β-Si3N4 has been carried out by means of first-principles calculations using the plane-wave pseudo-potential method with generalized gradient approximation for the exchange and correlation functional. The calculated maximum absorption coefficient is 312000, which is in good agreement with the other calculated result. β-Si3N4 can be used as a photo-electronic material because its absorption curve has an abrupt limit at low energy region. The light beam with the frequency of 7eV～15eV can easily traverse the β-Si3N4 crystal. For the dielectric function, the strongest peaks are located at 6.5 and 9.0eV for the real and imaginary parts, respectively. Moreover, the calculated static dielectric constant is 3.21. Actually speaking, our calculated results should be testified by experiments in the near future.

Abstract: Influence of sub-temperature quenching temperature on the tensile strength, hardness and toughness of 35CrMo steel was studied. The microstructure characteristics of this steel after sub-temperature quenching were analyzed. The results showed in the range of 780~810°C the strength and hardness of the 35CrMo steel sub-temperature quenched increased with quenching temperature increasing, reached the highest strength and hardness at 800°C quenching and then began to decrease, while its elongation decreased with the quenching temperature increasing. The duplex microstructure of martensite and ferrite was obtained by sub-temperature quenching of 35CrMo steel. With the quenching temperature increasing, the ferrite content decreased and the distribution of ferrite morphology was changed. A small amount of strip ferrite existed in lath martensite lamellar when quenching temperature was 800°C and the impact toughness of 35CrMo steel was better than that of conventional samples 850°C completely quenched.