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This paper proposes a systemic framework for dynamic safety risk analysis for natural gas pipeline leakage in a utility tunnel, which merges the bow-tie model (BT), Bayesian network (BN), a...

In magnetron sputtering systems, lead-zirconium-titanium oxide (PbZr1−xTixO3 or PZT) thin films were prepared in a mixture atmosphere of Ar and O2 with various oxygen partial pressures (0, 0.5, 1, 1.5 and 2% oxygen). About 600 nm PZT ferroelectric thin films were deposited on substrates, and then annealed at 600°C for 35 s. The structural, electrical and ferroelectric properties of PZT films were studied. As the oxygen partial pressure increased, the remanent polarisation rose first and went down later, and the leakage current density decreased first and then increased. At the oxygen partial pressure of 0.5%, we obtained the largest remanent polarisation and the minimum leakage current density. The XRD diffraction spectrum of all films displayed predominant (111) preferred orientation, and there was a weak XRD diffraction peak of pyrochlore phase in the PZT films deposited in pure Ar.

The study of soil enzyme activities under different land use is of importance for exploration of the soil quality evolution and its evaluation during the revegetation at karst area in Nanchuan, Chongqing, China. Seven kinds of land use were chosen as subject, aiming at revealing the changes in soil enzyme activities through experimental and statistical analysis. The results showed that different land use significantly influenced the enzyme activities. Soil urease, invertase, catalase and amylase behaved the different change. A descending order of urease activity was artificial forest, natural forest, shrubbery, grassland, slope field into terrace, rock desertification and farmland. As to invertase and amylase, they have no clear change orderliness with land use change. Moreover, no significant change was observed in catalase activity and the lower value was found in natural forest. The above results cannot reflect the land use effect on the enzyme activities. According to the soil enzyme index (SEI), it can be seen that the SEI changed with an order of natural forest > artificial forest > grassland > shrubbery > farmland > slope field into terrace > rock desertification, which can objectively and fully evaluate the land use change in soil enzyme.

Joining of components of cylindrical shape made of two materials chosen from Fe2Ni, 316L and M2 steels and manufactured by powder injection moulding (PIM) are studied in this paper. In general, joining of PIM cylindrical components requires that the to be joined outer part has a bigger shrinkage than the inner part during sintering. The sintered composite part consisting of Fe2Ni as outer layer and 316L as inner layer is a good example satisfying the above condition. Although the shrinkage of 316L and M2 are less than that of Fe2Ni, the composite parts with Fe2Ni as inner layer and 316L or M2 as outer layer can be successfully produced when different pretreatments are applied to Fe2Ni. Perfect diffusion joining without detectable pores in the vicinity of the bonding area is formed in Fe2Ni-1(or Fe2Ni-2)/316L(or M2) components. Diffusion of Cr and Ni elements has been verified by EDX analysis and it is shown that the diffusion accounts for the hardness of the transition zone.

Preliminary results of a high resolution coherent vacuum ultraviolet study of photoion-pair formation in HF/DF are reported. These results include threshold ion-pair production (TIPPS) and total photoion-pair yield spectra, which show sharp resonances due to predissociating Rydberg states. Detailed analysis of the spectra provides precise energies for the ion-pair thresholds, and insight into the mechanism for ion-pair formation.

Threshold ion-pair production spectroscopy (TIPPS) has been applied to two isotopomers, HCl and DCl. From the high-resolution TIPP spectra the ion-pair thresholds of the two molecules have been precisely measured. Combined with the known ionization energy of H(D) and the electron affinity of Cl, the difference between their bond dissociation energies is calculated, and therefore an experimental determination of the effect of Born–Oppenheimer breakdown on the dissociation limit of the ground state potential curve has been obtained. The difference in De for the two isotopomers was found to be: De(H–Cl)−De(D–Cl)=3.2±1.0 cm−1. The bond energy for HCl was in agreement with our previous determination, D0(H–Cl)=35748.2±0.8 cm−1. These results are compared to a recent study of Born–Oppenheimer breakdown in HCl by Coxon and Hajigeorgiou, where high resolution spectroscopic data was used to fit Born–Oppenheimer breakdown correction terms for the intramolecular potential function. The present study also measured the high resolution spectra for photoion-pair production for HCl and DCl in the threshold region for ion-pair production (∼86 nm). Although there is qualitative agreement between the current results and previous experimental and theoretical work, there are some important differences. The possible mechanism for ion-pair formation in HCl and DCl is discussed in light of these high resolution results.

We present the first threshold ion-pair production spectrum of a triatomic molecule. We have recorded the ion-pair yield spectrum and TIPP spectrum for the H2S → H++SH- ion-pair channel using single-photon excitation. From the TIPP spectrum, we have determined the H−SH bond energy (31451 ± 4 cm-1) to unprecedented accuracy and demonstrated the formation of weakly bound H+−SH- (J‘) ion-pair states, with rotational excitation of the SH- anion up to J‘ = 4. The bound nature of these states, and the assigned spectrum that results from their field dissociation suggests that this technique can be applied to many other triatomic and larger polyatomic molecules in the future, leading to energetic, spectroscopic, and dynamical information about these species.

The spectroscopic technique of threshold ion-pair production spectroscopy (TIPPS) has been applied to the triatomic molecule HCN. We have recorded the total ion-pair yield and TIPP spectra for the HCN-->H(+) + CN(-) process using coherent vacuum ultraviolet excitation. From the simulation of our high-resolution TIPP spectrum we have precisely measured the HCN ion-pair threshold E(IP) (0) to be 122 244 +/- 4 cm(-1). This value could be used to determine the bond dissociation energy D(0)(H-CN) to unprecedented accuracy. Our fitting result also showed that rotationally excited instead of cold CN(-) fragment is favored as the ion-pair dissociation product in the threshold region.

The protein product of the retinoblastoma (RB) gene is thought to function in a pathway that restricts cell proliferation. Recently, transforming proteins from three different classes of DNA tumor viruses have been shown to form complexes with the RB protein. Genetic studies suggest that these interactions with the RB protein are important steps in transformation by these viruses. In order to understand better the function of the RB-viral oncoprotein complexes, we have mapped the regions of the RB protein that are necessary for these associations. Two non-contiguous regions of RB were found to be essential for complex formation with adenovirus E1A or SV40 large T antigen. These two regions are found between amino acids 393 and 572 and 646 and 772. Interestingly, these binding sites on RB overlap with the positions of naturally occurring, inactivating mutations of the RB gene. These results strongly suggest that these viral oncoproteins are targeting a protein domain that is an important site in the normal function of the RB protein.