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The three-dimensional topography of the seabed has a significant influence on the wave field and the failure characteristics of the sloping seabed. Nevertheless, previous experimental studies were predominantly limited to two-dimensional wave conditions. In this study, a series of regular wave experiments (including a rigid-slope seabed and a sandy-slope seabed) have been done in a large-scale three-dimensional harbor basin to investigate the three-dimensional wave field in the Zhoushan sea area and the response characteristics of the sloping seabed under the wave actions, respectively. The results of the rigid-seabed tests show that the wave field has obvious three-dimensional characteristics under the influence of three-dimensional topography. During the process of propagation, wave shoaling occurs which leads to wave breaking finally. At the same time, the wave will reflect when it meets the topography, and the reflected wave will affect the wave field in turn. The pore water pressure response and three-dimensional failure modes of sandy sloping seabed under the wave actions are obtained by the sandy-seabed experiment. Three-dimensional seabed topography of typical sea area is established in the harbor basin. The characteristics of the three-dimensional wave field and the response of submarine slope under the three-dimensional wave actions were investigated. The three-dimensional topography of sandy sloping seabed after wave actions was captured. [ABSTRACT FROM AUTHOR]

A partial Sau3AI digest of genomic DNA from Streptomyces akiyoshiensis was cloned in a Streptomyces-Escherichia coli shuttle vector, and the recombinant plasmids were used to transform E. coli CGSC 6212, which has a mutation for aspartate semialdehyde dehydrogenase, to study the function of the core reactions in the biosynthesis of aspartate family amino acids and related secondary metabolites. Findings indicated that the asd and ask genes in S. akiyoshiensis are not found in an operon.

Three species involved in the nucleophilic substitution reaction of hydrosulfide ion and halomethanes are investigated by ab initio calculations. Geometries for stationary structures along the reaction paths are fully performed with the second-order Møller-Plesset perturbation approximation with the cc-pVDZ basis set. The monomer geometries determined by the MP2 method match the experimental results very well. Single point energy calculations are carried out at the coupled cluster with perturbative triple excitations CCSD (T) theory with aug-cc-pVDZ basis set. Halomethanes have three conformers here, which lead to the three product channels, HSCH3 + F−1, HSCH3 + Cl−1, and HSCH3 + Br−1. The investigation encompasses the six complexes formed among three channels, respectively. By selecting the six complexes as the model, we investigate the binding energy, topological property of the electron charge density and their Laplacian in detail theoretically. Electrostatic density potential maps of halomethanes are generated for the determination of attractive interaction sites. It is proved that the similar misshaped electron clouds of the three halogen atoms result in the similar properties of the carbon-halogen bonds, and reveals that the product ion-dipole complexes interactions are predominantly electrostatic in nature. The calculated results predict the binding energy of the most stable complex in six complexes is −47.06 kcal/mol at the MP2 level of theory. The second channel has the lowest energy barrier, which is −3.63 kcal/mol at the CCSD (T) levels of theory, is expected to be the most important pathway. It occurs via CCl cleavage accompanied by CS bond formation. The other two channels have higher energy barriers and are expected to have smaller rates. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 [ABSTRACT FROM AUTHOR]

Well Klari-2st is a directional exploratory well in Block Arar, Indonesia. In order to accomplish the exploration of the block, the Ø215.9 mm leaking openghole section is backfilled with cement; then drill with Ø152.4 mm drill bit and enlarge the hole with a reamer to form a Ø177.8 mm cement ring hole; then run in Ø149.2 mm expansion pipe to seal the wellbore so as to finish the 4th spud drilling. By analyzing the failure on pervious cement ring, we improved the cementing fluid system and added bentonite, fiber and expansion agent to the slurry to reduce the strength and brittleness of set cement stone and improve the toughness of set cement and its crosslinking intensity with well wall. By using shock-resistant high tenacity cement accompanied with the prepad fluid system of efficient flushing fluid and viscidity spacer fluid and other methods, we successfully pumped cement plugs, which satisfied the requirement that the maximum diameter of expansion pipe wellbore is less than Ø190 mm. [ABSTRACT FROM AUTHOR]