Papers by Keyword: Degradation

Abstract: This work analyzes the degradation of aluminum-composite adhesive joints under the action of water and motor oil. For this purpose, we have performed an accelerated ageing of the adhesive joint by immersion in water and oil. Likewise, we have evaluated the loss of mechanical properties that aging causes into adhesive joint. First, tests have been performed with bulk adhesive specimens (epoxy and polyurethane) immersed in water and motor oil during independent periods of time (1 at 128 days) in order to study the diffusion of water and motor oil into the adhesive. Second, we have evaluated the loss of mechanical properties that aging causes in the adhesive joint. Tests conclusions show that water degrades the adhesive more than motor oil. Additionally and under the action of water and motor oil, polyurethane adhesive joints retain their mechanical properties better than epoxy adhesive joints.

Abstract: The red ceramic pieces Campos-RJ degrade easily when they are in the built environment. With the intention to reduce the degradation in these pieces, was introduced petroleum coke in red ceramic. Petroleum coke is a solid fossil fuel, black in color and about granular form. With percentage of 0%, 0.5%, 1% and 1.5% clay added to the coke were obtained is prismatic ceramic samples. After drying at 110 ° C, fired at 800°C and 900°C and carried out at accelerated degradation in the laboratory by degradation equipment, obtaining the technological properties and Weibull distributions before and after degradation in the samples. The 900°C gave the highest Weibull modulus (m = 12.50) compared with the firing pieces at 800°C. The results show that the incorporation of 0.5% of petroleum coke improves the Weibull modulus of the degraded material.

Abstract: In this study, four model drugs, i.e., Meloxicam (MEL), Risperidone (RIS), Eprinomectin (EPR), and Bull Serum Albumin (BSA), were encapsulated in PLGA microspheres via solvent evaporation methods. The encapsulation efficiency and in vitro release profiles of different drugs with various water solubilities from medicated PLGA microspheres were investigated. The surface morphologies of microspheres were detected by scanning electron microscope (SEM). The release characteristics of the model drugs from the medicated microspheres were carried out in the phosphate buffer solution (PBS), pH7.4, at 37 °C. Studies found that the water solubility of model drugs had significant influences on their in vitro release profiles and the release rates of four model drugs were in the orders of BSA＞MEL＞RIS＞EPR.

Abstract: The loaded specimens were put in fresh water, 3.5%NaCl solution, 5.0%Na₂SO₄ solution, and simulated sea water with different concentrations respectively, and then the damage process under wetting and drying cycle was investigated. The ultrasonic non-metal testing technology, X-CT scanned image, free chloride and sulfate ions chemical titration were used to investigate the degradation of the marine concrete under the coupling effect of Chemistry and Mechanics. The effect of solutions, wetting and drying cycle and bending stress to the durability of marine concrete were further studied. The results indicate that different salt solution affects marine concrete at different degrees: sulfate salt is more corrosive than chloride salt, simulated seawater is similar to 5.0%Na₂SO₄ solution, while five-time simulated seawater is the most corrosive; wetting and drying cycle remarkably accelerates the penetration of corrosive ions, which results in the concrete damage, compared to the corrosive environment, concrete is damaged violently under the coupling effect of Chemistry-Mechanics and tensile stress has greater influence on the damage.

Abstract: the green design appeared in the 1980 s, this paper mainly introduces the concept of green design, features, basic principles of design, and the method of green design and the development trend of green packaging in our country. From the perspective of protecting the environment and resources, I put forward the significance of developing green packaging design and point out how to develop and perfect the green packaging design in our country based on analysis.

Abstract: Due to the inconvenience of characterization of the degradation of power battery based on capacity fading, this paper proposes a new characterization measure for battery degradation based on declining point. After the declining point is defined and calculated, Olivier-Louis mode is used to fit the discrete discharge experimental data from NASA, the linear correlation between the declining point and capacity is confirmed by correlation analysis and regression analysis, therefore the declining point is verified to be an effective characterization measure of battery degradation.

Abstract: Degradation performances of Klebsiella spp. for Cyclohexane was studied by using the method of single factor in the paper. The influences of temperature, pH, initial concentration of Cyclohexane, oxygen supply, culture time etc. were studied and the optimum conditions were determined. The results show that the activated strains of Klebsiella spp. are inoculated in the liquid culture medium of 100 ml which contained cyclohexane, the initial concentration of cyclohexane is 2490 mg/L, the culture temperature is at 28°C, pH is 6, the number of Klebsiella spp. is about 9×10⁵ ml^-1 in the liquid culture medium, the speed of rotary shaker is 120 r/min, and the degradation rate of Cyclohexane reaches 70.1% in 96 hr. The results could provide the theoretical basis in the field of pollution treatment of petroleum hydrocarbons.

Abstract: Uniform immobilization of BiFeO₃ on silica fiber was successfully obtained by a combined impregnation method with carbon nanofibers (CNFs) template route. The physicochemical properties of the obtained material were characterized by means of X-ray diffraction, field emission scanning electron microscopy, and ultraviolet-visible diffuse reflectance spectroscopy. It turned out that BiFeO₃ immobilized on silica fiber can exhibit visible light photocatalytic degradation of rhodamine B (RhB) to some extents. It is expected that such kind of material would possess many potential applications in photocatalysis.

Abstract: This study evaluated the in vitro degradation of pellet, powder and plates of poly-L-DL-lactic acid (PLDLLA) after two processing methods. Part of the material was reduced to powder by cryogenic milling and part of it molded injected in plate form. The crystallinity was evaluated by Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), and Gel Permeation Chromatography (GPC) before and after immersion in simulated body fluid for 30, 60, and 90 days. The glass transition temperature (T_g) of the pellets and the powder were 61.5°C, 66°C. The T_gs of the plates ranged from 59.55°C to 63.06°C. Their endothermic peaks were observed at 125°C and 120°C, which was not identified to the plates samples. The FTIR spectrum showed bands of amorphous and crystalline content. The XRD results showed a peak related to the crystalline content, and a wide reflection related to the amorphous content. The milling process increased the crystallinity and the molding injection decreased it.

Abstract: Oil production offshore and onshore results in production of huge amount of water, called produced water (PW). PW is one of source of polycyclic aromatic hydrocarbons PAHs to the aquatic environment. Degradation kinetics of 16 priority PAHs were studied in PW treatment using Ti/RuO₂ anode in a batch setupat three different current densities 3.33, 6.67 and 10 mA/cm². GC-MS was used for quantification of each PAH. Kinetics study confirmed that electrochemical degradation of all PAHs had follow first-order kinetic using Ti/ RuO₂. Results showed that values of rate constant k were increase by increasing current density.