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Icebreaking by using underwater explosion bubbles and compressed high-pressure gas bubbles has gradually become an effective icebreaking method. In order to compare the damaging effect of these two methods on the ice body, a fluid–structure coupling model was established based on the arbitrary Lagrangian–Eulerian (ALE) method and a series of calculations were carried out. The morphological changes of underwater explosion bubbles and compressed gas bubbles at the same energy under the free surface; the changes of flow load near the rigid wall; and the damage caused to the ice plate were studied and compared. The damage effect of the ice plate was analyzed by detecting the number of failure elements of the ice plate, and the optimum standoff distance was found. For an ice plate with a radius of 0.19 m and a thickness of 0.15 m, the optimum standoff distance of the compressed gas bubbles with 120 J is 0.03 m, and the optimum standoff distance of the TNT with 120 J is 0.02875 m. The similarities and differences of the two sources of bubbles on ice plate damage were summarized. [ABSTRACT FROM AUTHOR]

The chiral flip mechanism of S- a -alanine (S- a -Ala) and tetravalent selenium ( Se (IV )) complexes(S-a-Ala Se(IV)) was studied by means of M06 and MN15 methods based on density functional theory and SMD model method of polarized continuum. The study of reaction channels shows that S-a-Ala- Se(lV) can be transferred when the carbonyl O atom as the only medium of a-H proton; the proton transfers to a-C from amino group N after the a-H proton is transferred to carbonyl O atom; after the proton of protonated amino transfers to carbonyl O atom α-H proton achieves chiral flip in three channels with amino group N as the medium of protolysis. Investigation on the potential energy surface shows that the third reaction channel has the most advantage, the free energy barrier is 227.6 kJ/ mol under the effect of recessive solvent, it comes from the transient state of the proton moving from amino group N to α-C, Under the dominant solvent effect, the free energy barrier is 155.6 kJ/mol,it comes from the transient state of the proton moving from protonated amino group N to carbonyl O atom. The results show that chiral α -Ala·Se is difficult to racemize in water-liquid phase, and thus it is relatively safe to be used to supply α-Ala and Se(IV) for life simultaneously. [ABSTRACT FROM AUTHOR]

The chiral flip mechanism of S- α-alanine (S- α-Ala) and tetravalent selenium (Se (IV)) complexes (S-α-Ala⋅Se (IV)) was studied by means of M06 and MN15 methods based on density functional theory and SMD model method of polarized continuum. The study of reaction channels shows that S-α-Ala⋅Se (IV) can be transferred when the carbonyl O atom as the only medium of α-H proton; the proton transfers to α-C from amino group N after the α-H proton is transferred to carbonyl O atom; after the proton of protonated amino transfers to carbonyl O atom, α-H proton achieves chiral flip in three channels with amino group N as the medium of protolysis. Investigation on the potential energy surface shows that the third reaction channel has the most advantage, the free energy barrier is 227.6 kJ/mol under the effect of recessive solvent, it comes from the transient state of the proton moving from amino group N to α-C; Under the dominant solvent effect, the free energy barrier is 155.6 kJ/mol, it comes from the transient state of the proton moving from protonated amino group N to carbonyl O atom. The results show that chiral α-Ala⋅Se (IV) is difficult to racemize in water-liquid phase, and thus it is relatively safe to be used to supply α-Ala and Se (IV) for life simultaneously. [ABSTRACT FROM AUTHOR]

The study investigated the effect of water molecule(cluster) and aqueous solvent on S-proline( Pro)divalent copper complex(S-Pro·Cu(II))enantiomerization under the gas phase using the methods of M06 and MN15 based on density functional theory combining with self-consistent reaction field of SMD model. The results showed that gas phase Cu2+ and carbonyl O monodentate ligand is the most stable. The enantiomerization of S-Pro•Cu(II)can be realized in 5 channels a, b, c, d and e. In channel a, b and c α -H transfers directly with O, Cu and N as a bridge respectively. After Cu and carbonyl O are bidentately coordinated α-H transfers with O and O and N unite as a bridge in channel c and d(α-H transfers with Cu as a bridge, it is hydrogen anion migration. The other is hydrogen proton migration). The potential energy surface calculation shows that the dominant pathways of the enantiomerization of isolated S-Pro•Cu(II) are pathways b and c, and the activation energy of the reaction is 153. 4 and 160. 3 kJ·mol, 1 respectively. The dominant pathway is channel c in the water vapor phase environment and the activation energy of the reaction is 143. 7 kJ·mol-1. Channel b is the most disadvantaged, and the enantiomerization in this channel cannot be achieved. The activation energy of channel c drops to 89. 9 kJ·mol-1 under the effect of aqueous solvent. The results show that Pro•Cu) can maintain its chiral characteristics well in the gas phase, and is easy to be enantiomerized in the water vapor phase. [ABSTRACT FROM AUTHOR]

Overquenched Pr7Fe88B5 ribbons were studied during annealing for phase transformations and magnetic properties.