Applied Mechanics and Materials Vols. 556-562

Abstract: Insulin is essential for maintaining glucose homeostasis and is synthesized and secreted almost exclusively from pancreatic β-cells in the islets of Langerhans. The analysis of rat insulin2 promoter sequences indicates that it has pancreatic and duodenal homeobox factor-1 (PDX-1) binding site. In mature β-cells, PDX-1 transactivates the insulin and other genes involved in glucose sensing and metabolism. The function of PDX-1 can be regulated by post-translational modifications. Sumoylation plays an important role in regulating numerous physiological and pathological processes through altering the function of its target proteins. In this paper, to understand the function and transcription activities of insulin gene promoter, we constructed rat insulin 2 promoter (RIP II). Then we investigated whether sumoylation of PDX-1 activated this promoter transcription by luciferase reporter assay in HepG-2 cells. Results indicated that sumoylation enhanced PDX-1 activity for the insulin gene promoter transcription.

Abstract: PCNA (proliferating cell nuclear antigen) is a protein related to tumor development, which has been used extensively in breast cancer diagnosis and prognosis. PCNA has proven to be a useful marker to evaluate cell proliferation and prognosis when combined with other breast cancer markers. Construction of PCNA promoter luciferase reporter plasmid will provide the theory basis for researching the effect of other transcription factors on regulating PCNA transcription. In this study, a human PCNA promoter luciferase reporter construct was generated by PCR amplification of PCNA promoter. The PCR fragment was digested and cloned into pGL3 vector. The promoter sequence was verified by sequencing. The results showed that luciferase reporter plasmids of PCNA promoter were successfully constructed. Then the effects of some key transcription factors, which play important roles in breast cancer cell proliferation, were investigated by luciferase reporter assays in MCF-7 cells. The results showed that ERα can enhance transcriptional activity of PCNA. Furthermore, 17-β-estradiol (E2) also shows an obvious impact in activating PCNA transcription. Our data illuminated that E2 enhances ERα-induced proliferation potential of MCF-7 cells by stimulating the transcriptional activity of PCNA. Our research will provide a model to screen some novel factors in regulating proliferation marker transcription.

Abstract: The failure analysis of the H13 steel hot-forging mould is the main content in the open experiment. The scan electronic microscope and the optical microscope are used to analyze the failure workpiece in this experiment. The over-high quenching temperature, the too low drawing temperature, the insufficient drawing time and frequency, the over-high hardness value are the main reasons of fracture failure of the mould. The work environment of the failure materials, the heat treatment processing, the metallographic analysis, the fracture analysis and the using of test standard are the important aspects which the students should know. The students can learn how to analyze problem and how to solve them from the open experiments which is a good teaching try.

Abstract: According to the operating characteristics of high-power battery pack in practical application, the effects of four factors, which include operating load, state of charge (SOC), ambient temperature and operating temperature, on the temperature uniformity and rising rate of battery pack under natural convection were studied based on Arbin test bench. The results indicate that: the operating load and SOC of battery pack doesn’t affect its temperature uniformity, which was deteriorated as the increasing of operating temperature of battery pack, or improved as the increasing of ambient temperature when the other factor is kept constant. The increment of operating load or ambient temperature could result in a higher temperature rising rate, while the increasing of SOC or operating temperature could lead to a lower temperature rising rate, when the other three factors are kept constant. When the operating temperature or temperature differences achieved threshold value, thermal management system should choose proper extent of forced flow and flow field in accordance with the battery pack’s current operating conditions, in order to ensure the economy of the thermal management system.

Abstract: Based on the HPPC test data of 8Ah/144V lithium-ion battery pack, the PNGV model parameters are identified when operation temperature of battery pack is 20°C and the model of PNGV of high-power lithium ion battery pack is build. According to actual operation characteristics of high-power battery pack, the actual output voltage and model predictive voltage are compared under the high-power battery pack different operating condition based on Arbin test bench. It’s showed that the PNGV model predictive precision is not high when high-power battery pack is under steady state condition; the model predictive precision is high when high-power battery pack is under dynamic condition; the difference between model predictive voltage and actual output voltage will be bigger as the operation temperature increased.

Abstract: The precipitated carbides amount change after quenching and tempering the steel can be clearly observed by scanning electron microscope (SEM). The hidden needle martensite in high speed steels can be also clearly showed. Compared with the optical differential microscopy, the result of SEM shows significant differentiation. The application of SEM in metallurgical experimental teaching is feasible and necessary, with excellent experimental teaching effect.

Abstract: SnS thin film, a potential earth-abundant photovoltaic material, has particularly generated interest because of its nontoxic nature, the band gap of it matches well with solar spectrum and its high absorption coefficient. It provides a brief description of the development of SnS thin film for solar cells, and surveys several preparation methods of SnS thin film, then introduces the crystal structure of SnS. The effects of different doping elements and concentrations for SnS thin film on performance were outlined, and the development and the structure of solar cells based on SnS thin films were discussed. Finally, the development tendency and prospects were predicted.

Abstract: In this study, Biosorption of Ni (II) ions from aqueous solution by using biomass of Aspergillus niger was investigated. Different parameters such as initial pH, Ni (II) ions concentration, contact time and temperature were explored. The biosorption of Ni (II) ions was highly pH dependent and the optimum pH for biosorption of Ni (II) ions was found to be 7.0. The biosorption equilibrium was established in about 30min of contact time. Ni (II) ions removal increased with increasing temperature in the studied range. Equilibrium uptake of Ni (II) ions onto biomass increased with increasing initial Ni (II) ions concentration (20-300mg/L). The Langmuir and Freundlich isotherm models were applied to experimental equilibrium data and the Langmuir model better described the equilibrium metal uptake than the Freundlich model. These results suggest that the biomass of Aspergillus niger is a promising biosorbent for removal of nickel (II) ions from the wastewater.

Abstract: In this study, Biosorption of Cr (VI) ions from aqueous solution by using biomass of Aspergillus niger was investigated. The effects of initial solution pH, biosorbent amount, contact time, initial concentration and temperature were explored. In batch experiments, the biosorption capacity of Cr (VI) decreased with increase in solution pH. The biosorption of Cr (VI) ions with pH range of 2.0-8.0 was found to be optimal at pH 2. Biosorption capacity of Cr (VI) ions decreased with increased biosorbent dosage. The bosorption capacity was increased with the increasing initial Cr (VI) concentration and temperature in studied range. The biosorption process followed the pseudo-second order kinetic model and the correlation coefficients from the pseudo-second order model were all higher than 0.9997 in all studied temperatures. These results suggest that the biomass of Aspergillus niger is a promising biosorbent for removal of Cr (VI) ions from the wastewater.

Abstract: It introduces a kind of technique method that recycling sylvite zinc plating waste liquid laboratory, involving the fields in electroplating and comprehensive utilization of waste liquid. It includes the following steps: first add hydrogen peroxide and activated carbon into waste liquid to remove the organic matter in it, and then reduce the solution’s temperature with refrigeration film, and filter out the solid contents. Add NaOH solid, NaHSO₃ into the solution, through chemical reactions, precipitate the heavy metal element, and finally get distilled water through distillation. It can make the recycled materials be reused, such as distilled water, boric acid, etc., and as to nonrecyclables, such as heavy metal ions (Cu²⁺, Cr³⁺), bury them deep that disposing harmless.