Advanced Materials Research Vols. 490-495

Abstract: The purpose of this paper is to estimate the fast determination of stress distribution around a circular hole in symmetric composite laminates under in-plane loading. For this purpose calculation of stress values in the composite plate around edge holes in different plies position for a finite number of input data sets using the Lekhnitskii expressions and code program. The resulting data would then be used to train artificial neural networks (ANN) which would be able to predict –accurately enough- those quantities throughout the composite plate body for any given input value in any position ply and fore and stress that impose.

Abstract: The effects of aging temperature and aging time on properties of Cu-2.1Ni-0.5Si -0.2Zr-0.05Cr (wt.%) alloy were studied. The transformation ratio of new phase in Cu-2.1Ni-0.5Si-0.2Zr-0.05Cr alloy was calculated when aging at 400°C, 450°C and 500°C by measuring electrical conductivity, the relation between the electrical conductivity and the quantity of new phase. The Avrami-equation of phase transformation kinetics and the Avrami-equation of electrical conductivity during aging were established for Cu-2.1Ni-0.5Si-0.2Zr-0.05Cr alloy, on the basis of linear relationship between the electric conductivity and the volume fraction of precipitates. The calculated values of electrical conductivity well consistent with those of experiment can provide reference on the alloy of production process. The characteristics of precipitates in the alloy after solution treatment and cold rolling were established, and the results show the precipitate was δ-Ni2Si phase.

Abstract: With six-speed rotary viscometer measuring the rheology of drilling fluid at low temperature, during the high-speed process, the drilling fluid temperature is not constant at low temperature, which leads to the inaccuracy in rheological measurement. When R/S rheometer is used cooperating with constant low-temperature box , the temperature remains stable during the process of determining the drilling fluid rheology under low temperature. The R/S rheometer and the six-speed rotational viscometer are both coaxial rotational viscometers, but they work in different ways and the two cylindrical clearance between them are different.How to make two viscometer determination result can maintain consistentThe experimental results show that, The use of R/S rheometer, with the shear rate for 900s-1 shear stress values instead of six speed rotary viscometer shear rate for 1022s-1 shear stress values.Then use two-point formula to calculate rheological parameters.The R/S rheometer rheological parameter variation with temperature has a good linear relationship,Can better reflect the rheological properties of drilling fluids with low temperature changerule

Abstract: In the present study, the Effect of rare earths on mechanical properties and wetting behavior of Sn-2.5Ag-0.7Cu solder were investigated. Results indicate that the addition of trace rare earths can improve the properties of Sn-Ag-Cu lead-free solder. The elongation and tensile strength and wetting force of solder can reach the optimal values when rare addition is 0.1wt.%. But excessive rare earths can lead to performance decline. The properties change of the Sn-2.5Ag-0.7Cu solder are attributed to the change of the microstructure caused by trace rare earths additions.

Abstract: The aim of this study is to evaluate the characterizations of alginate-chitosan hydrogel for wound dressing application. The influence of alginate concentrations (1%, 2%, 3% and 4% (w/v)) was investigated. An increase in alginate concentration leads to a decrease in swelling capacity but an increase in holding capacity. All the hydrogels exhibited above 80% water holding abilities. The hydrogel leach outs were nontoxic to the cells, as confirmed by MTT assay. Taken together these results point out that alginate-chitosan polyelectrolyte hydrogel can be considered for wound dressing applications.

Abstract: Evaluation of glass-forming ability (GFA) is important in the development of amorphous alloys. Based on phase field theory, the kinetic model of liquid-to-solid phase transition is build, and the time-temperature-transformation (TTT) diagram is plotted according to the phase field simulations of isothermal phase transformation kinetics for a model system. Furthermore, the critical cooling rate for glass formation is calculated on the basis of the TTT curve and is taken as the intrinsic criteria of reflecting the GFA for metallic melts.

Abstract: After ethylene diamin tetra-acetic acid (EDTA) chelating 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 EDTA is 0.6%, the removal result of metal ions is the best. After chelating pretreatment, the pulp’s brightness has been increased about 4.3%ISO~5.2%ISO, the pulp’s hardness has been reduced by 0.7%~1.0%, and the pulp’s viscosity has been kept well. Besides, when the added dosage of EDTA is 0.6%, 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 pretreatment, the results has been found that the brightness of photocatalysis bleached pulp been increased about 3.0%ISO, and the decreasing rates of hardness reach to the maximum, and the viscosity remains well.

Abstract: Double perovskite (Sr1.85Ln0.15)FeMoO6 (Ln=Sr, La, Ce, Pr, Nd, Sm and Eu) have been prepared by solid-state reaction. Crystal structure investigation shows that all the samples are of single phase and belong to the I4/m space group. Saturation magnetization of the compounds at 5 K cannot be explained simply by ferrimagnetic model (FIM). However, the saturation magnetization at 100 K of the doped compounds exhibits a linear decrease with the increase of the anti-site defect concentration. Comparison of the saturation magnetization of the compounds at 5 K and 100 K suggests that at 5 K the magnetic moments of Ce, Pr, Nd and Sm align parallel with that of Fe, while the magnetic moment of Eu is anti-parallel with that of Fe.

Abstract: CaMoO4 microcrystals with controllable morphologies and luminescent properties were successfully synthesized via hydrothermal treatment. The as-prepared samples are characterized using X-ray powder diffraction, scanning electron microscopy; Fourier transformed infrared spectra. By adjusting the fundamental experimental parameters including reaction time, temperature and the amount of organic additives, CaMoO4 exhibited various morphologies, such as particles, dumbbells as well as flowers. Moreover, it is seen that CaMoO4 can be well crystallized with tetragonal structure at room temperature. The photoluminescence spectra of CaMoO4 display a strong and broad band emission with a maximum at 550 nm under excitation wavelength of 310 nm at room temperature. The luminescent intensity of CaMoO4 varied with the reaction time and temperature and was optimized at 200 oC, 45 h. The work provides a facile synthetic route for the construction of inorganic materials with controllable morphologies and luminescent properties

Abstract: For the purpose of developing liquid crystalline micro-actuators, the transient behaviors of a nematic liquid crystal between two parallel plates have been computed for various parameters such as applied voltage, the gap between the plates, and the twist and tilt angles at the plates. The Leslie–Ericksen theory has been selected as a constitutive equation. As conclusion of this study, we can develop micro-actuators with arbitrary characteristics by suitably controlling the applied voltage, the size of the actuators, and the director anchoring conditions.