The correlation between structural, stereochemical as well as electronic features and ambergris odor of some tricyclic ethers is established based on quantum chemical calculation method. A definite structural fragment (a "new ambergris triangle") with certain electronic properties determining the origin of the odor is revealed. The influence of HOMO-LUMO energy gaps and total energies of some ambergris compounds on their odor intensity is investigated.

Ab initio (MP2) and density functional theory (DFT) methods were used to examine nine isomers of the doublet BN(4) species with the 6-311 + G(d) basis set. To our knowledge, these nine structures are all first reported here. Energy analysis indicates that the C(2v) branched structure is the global minimum of potential energy surface. Research results show that the C(2v) branched, the cis-linear, the C(4v) pyramidal, and the C(S) five-membered ring structures are likely to be stable and to be observed experimentally. Among these four kinetically stable species, the last three are suitable to be used as potential precursors of HEDMs due to their high dissociation energies. However, the C(2v) bent, the trans-linear, the D(2) bicyclic, the C(2v) four-membered ring, and the C(2v) cage structures are kinetically unstable due to their low dissociation or isomerization barriers. Two synthesis pathways of the C(2v) branched isomer were located. It seems more feasible to synthesize this species by linear NBN and N(2).

Barnacle is a major creature in marine fouling organisms, it increases static load and dynamic load of marine structures. In this paper, the change of stress on marine concrete surface covered with barnacles is studied. Moreover, a simplified model is established. The result shows that the stress of seawater increases by 0.53 times on the concrete surface, which is covered with barnacles.