Hydrogen Flux Inhibition of Pd-Ru Membranes under Exposure to NH3.

The hydrogen flux inhibition of Pd-Ru membranes under exposure to 1-10% NH3 at 673-773 K was investigated. The Pd-Ru membranes were characterized by XRD, SEM, XPS, and hydrogen permeation tests. The results show that when exposed to 1-10% NH3 at 723 K for 6 h, the hydrogen flux of Pd-Ru membranes sharply decreases by 15-33%, and the decline in hydrogen flux becomes more significant with increasing temperatures. After the removal of 1-10% NH3, 100% recovery of hydrogen flux is observed. XPS results show that nitrogenous species appear on the membrane surface after NH3 exposure, and the hydrogen flux inhibition may be related to the competitive adsorption of nitrogenous species. By comparing the hydrogen flux of Pd-Ru membranes exposed to 10% NH3 with 10% N2, it is indicated that the rapid decrease in hydrogen flux is due to the concentration polarization and competitive adsorption of nitrogenous species. The competitive adsorption effect is attenuated, while the concentration polarization effect becomes more pronounced with increasing temperature.

Microstructure Evolution of the Semi-Macro Segregation Induced Banded Structure in High Strength Oil Tubes During Quenching and Tempering Treatments.

C110 oil well casing tubes should have high strength and corrosion resistance which is commonly used for deep wells operation containing corrosive media. In this paper, the microstructure evolution of a kind of semi-macro segregation originated banded structure in casing tubes is studied under different heat treatments. It is shown that the characteristics of the banded structure will change significantly in subsequent hot working and heat treatment processes. For the hot-rolled ones, the banded structure is composed of pearlite plus bainite. After quenching, it evolves into martensite band with high concentration solute elements. Finally, the banded structure will change into a carbide banding under the following tempering process. The temperature and cooling rate of the tempering practice show an obvious effect on the final band structure. To improve anti-SSC (sulfide stress corrosion cracking) performance, the favorable QT (quenching and tempering) practice for C110 steel should be a higher tempering temperature and a quicker cooling rate, from which the banded structure defects can be decreased together with an obvious improvement of the tube wall hardness uniformity.

The Refining Mechanism of Super Gravity on the Solidification Structure of Al-Cu Alloys.

There is far less study of the refining effect of super gravity fields on solidification structures of metals than of the effects of electrical currents, magnetic and ultrasonic fields. Moreover, the refining mechanisms of super gravity are far from clear. This study applied a super gravity field to Al-Cu alloys to investigate its effect on refining their structures and the mechanism of interaction. The experimental results showed that the solidification structure of Al-Cu alloys can be greatly refined by a super gravity field. The major refining effect was mainly achieved when super gravity was applied at the initial solidification stage; only slight refinement could be obtained towards the end of solidification. No refinement was obtained by the super gravity treatment on pure liquid or solid stages. The effectiveness of super gravity results from its promoting the multiplication of crystal nuclei, which we call "Heavy Crystal Rain", thereby greatly strengthening the migration of crystal nuclei within the alloy. Increasing the solute Cu content can increase nucleation density and restrict the growth of crystals, which further increases the refining effect of super gravity. Within this paper, we also discuss the motile behavior of crystals in a field of super gravity.

The irradiation effect of a simultaneous laser and electron dual-beam on void formation.

Randomly distributed lattice point defects such as supersaturated vacancies (SVs) and Frenkel-pairs (FPs, an interstitial and a vacancy) can be simultaneously introduced into the crystal by energetic beam irradiation in outer space and/or nuclear reactors, but their behavior has not been fully understood. Using a high-voltage electron microscope equipped with a laser (laser-HVEM), we show the striking effects of simultaneous laser-electron (photon-electron) dual-beam irradiation on void formation. Our results reveal that during laser-electron sequential irradiation, pre-laser irradiation enhanced void nucleation and subsequent electron irradiation enhanced void growth. However, the laser-electron dual-beam irradiation was analyzed to depress void swelling remarkably because the recombination of SVs and interstitials was enhanced. The results provide insight into the mechanism underlying the dual-beam radiation-induced depression of void swelling in solids.

Dislocation loop formation and growth under in situ laser and/or electron irradiation.

Vacancies and interstitial atoms are primary lattice (point) defects that cause observable microstructural changes, such as the formation of dislocation loops and voids in crystalline solids. These defects' diffusion properties determine the phase stability and environmental resistibility of macroscopic materials under ambient conditions. Although in situ methods have been proposed for measuring the diffusion energy of point defects, direct measurement has been limited. In this study, we propose an alternative in situ method to measure the activation energy for vacancy migration under laser irradiation using a pulsed laser beam from a laser-equipped high-voltage electron microscope (laser-HVEM). We made in situ observations that revealed the formation and growth of vacancy dislocation loops in an austenitic stainless steel during laser irradiation. These loops continued to grow when thermal annealing was performed after laser irradiation at the same temperature. We anticipate that laser-HVEM will provide a new method for investigating lattice defects.

Small interference RNA targeting Krüppel-like factor 8 inhibits the renal carcinoma 786-0 cells growth in vitro and in vivo.

PURPOSE: Krüppel-like factor 8 (KLF8) plays an important role in oncogenic transformation and is highly overexpressed in several types of human cancer. We investigated the expression of KLF8 in renal cell carcinoma (RCC) tissues and the role of small interference RNA targeting KLF8 on growth, cell cycle, and apoptosis of human renal carcinoma cell line 786-0 in vitro and in vivo. METHODS: The expression of KLF8 protein and mRNA in human renal carcinoma samples was detected by immunochemistry and reverse transcription polymerase chain reaction (RT-PCR). The effects of small interference RNA (siRNA) targeting KLF8 on growth, invasiveness, cell cycle, and apoptosis of 786-0 cells were evaluated by MTT assay, Matrigel Invasion Assay, and flow cytometry in vitro. We also investigated effect of siRNA targeting KLF8 on growth of 786-0 cells in nude mice in vivo. RESULTS: Immunohistochemistry and RT-PCR results showed the expression of KLF8 protein and mRNA in RCC specimens was significantly higher than that in the adjacent non-tumorous renal tissues (P < 0.001). KLF8-siRNA depressed the cellular growth and invasion of 786-0 cells in vitro. The flow cytometry results revealed that KLF8-siRNA could induce an increase in G0/G1 phase cells and induce cell apoptosis. Intratumor injection of siRNA targeting KLF8 inhibited the growth of 786-0 cells in vivo in nude mice tumor model. CONCLUSIONS: KLF8 possibly involved in regulating the cell growth, invasion, apoptosis, and proliferation of renal carcinoma cancer cells. Blocking the KLF8 channel might be a potential therapeutic strategy for RCC.

Upregulation of GRP78 in renal cell carcinoma and its significance.

OBJECTIVES: To investigate the expression of GRP78 in human renal cell carcinoma (RCC) and its significance. METHODS: We studied RNA and tissue section of a tumor and adjacent nontumorous renal tissues obtained from radical nephrectomy specimens of 42 patients and RCC cell lines. We used reverse transcriptase-PCR and immunohistochemistry to detect the GRP78 mRNA and protein expression, respectively. RESULTS: Reverse transcriptase-PCR revealed that GRP78 mRNA is positively expressed in RCC cell lines (786-0, OS-RC-2, and Caki-1); the GRP78 mRNA expression in the RCC and adjacent nontumorous renal tissues was 0.88 +/- 0.34 and 0.44 +/- 0.15, respectively (P < .001). The GRP78 protein was found in RCC cell lines. Immunohistochemistry results also showed that the level of GRP78 protein expression of RCC tissues was significantly higher than that of the adjacent nontumorous renal tissues (P < .001). The high levels of GRP78 mRNA and protein expression were related to the large tumor size and high clinical stage (P < .001) but not to sex, age, and cell differentiate (P > .05). CONCLUSIONS: To our knowledge, the present study is the first to report the upregulated expression of GRP78 and that it is possibly involved in pathogenesis of RCC.