Luo Shunzhong

Simulation of Helium Behaviour in Titanium Crystals Using Molecular Dynamics

The behaviour of helium in Ti crystals at 300 K has been investigated by means of the molecular dynamics. The study is focused on the influences of He–Ti interaction on the aggregation of helium atoms in the substrate. When a Born–Mayer potential is used to describe the He–Ti interaction, the He atoms are unable to cluster with each other due to the weak bridge barrier that cannot trap the helium atoms, Whereas using a He–Ti potential that is constructed by fitting the ab initio pairwise He–Ti potential, the clustering of He atoms can be observed. The results indicate that suitable He–Ti potential plays an important role in the formation of He clusters in metals. Moreover, it is noted that the shape of the formed He cluster is irregular, and the produced defect prefers to congregating on one side of the He cluster rather than spreading symmetrically around it.

Crescent aromatic oligothioamides as highly selective receptors for copper(II) ion

A series of crescent aromatic oligothioamides (4, 6, 8, 15, and 18) bearing different number of sulfur atoms were designed and synthesized via thionation of their corresponding aromatic oligoamides (3, 5, and 7) using Lawesson’s reagent. The X-ray structure of a trimeric analogue (13) revealed the presence of intramolecular three-center hydrogen bonds that are responsible for the rigidification of the molecular backbone. The extraction by these novel receptors toward some representative heavy metal cations (Zn2+, Cd2+, Co2+, Ni2+, Pb2+, and Cu2+) and alkali and alkaline earth metal cations (Li+, Na+, K+, Rb+, Cs+, Ca2+, and Sr2+) demonstrated high efficiency (83.5%–96.4%) and superior selectivity for Cu2+ over other selected metal cations. Particularly, the extractability was correlated to both the number of sulfur atoms and orientation of thiocarbonyl groups as revealed in the order: 6 > 4 > 18 > 15. This is in stark contrast to the oligoamides that only gave much lower extractability (5.9%–16.4%), suggestive of the importance of replacement of carbonyl oxygen atoms with sulfur atoms in the extraction of Cu2+. The complexation behavior of 4, 6, and 8 with Cu2+ was also examined by UV-Vis and NMR techniques.

Effects of Substrate Temperature on Helium Content and Microstructure of Nanocrystalline Titanium Films

Helium-charged nanocrystalline titanium films have been deposited by He?Ar magnetron co-sputtering. The effects of substrate temperature on the helium content and microstructure of the nanocrystalline titanium films have been studied. The results indicate that helium atoms with a high concentration are evenly incorporated in the deposited titanium films. When the substrate temperature increases from 60?C to 350?C while the other deposition parameters are fixed, the helium content decreases gradually from 38.6?at.% to 9.2?at.%, which proves that nanocrystalline Ti films have a great helium storage capacity. The 2? angle of the Bragg peak of (002) crystal planes of the He-charged Ti film shifts to a lower angle and that of (100) crystal plane is unchanged as compared with that of the pure Ti film, which indicates that the lattice parameter c increases and a keeps at the primitive value. The grain refining and helium damage result in the diffraction peak broadening.

Molecular Dynamics Simulations of Helium Behaviour in Titanium Crystals

Molecular dynamics simulations are performed to investigate the behaviour of helium atoms in titanium at a temperature of 300K. The nucleation and growth of helium bubble has been simulated up to 50 helium atoms. The approach to simulate the bubble growth is to add helium atoms one by one to the bubble and let the system evolve. The titanium cohesion is based on the tight binding scheme derived from the embedded atom method, and the helium–titanium interaction is characterized by fitted potential in the form of a Lennard-Jones function. The pressure in small helium bubbles is approximately calculated. The simulation results show that the pressure will decrease with the increasing bubble size, while increase with the increasing helium atoms. An analytic function about the quantitative relationship of the pressure with the bubble size and number of helium atoms is also fitted.

Preparation and properties of 117mSn(IV)-TTHMP in in-vitro and in small animals

In this work, TTHMP was synthesized and labelled with 117mSn. The preparation conditions, stability and lipophilicity of 117mSn(IV)-TTHMP were investigated. Biodistribution of the complex in rabbits and mice was studied. It was found that the quantity of TTHMP and pH value of the preparation solution had vital effects on the labeling yield of 117mSn(IV)-TTHMP. It was also found that 117mSn(IV)-TTHMP was hydrophilic and stable at room temperature and 37°C in open air. 117mSn(IV)-TTHMP showed unexpectedly high bone uptake and bone-to-blood ratio in the animals. This made it potentially useful as an reagent for skeletal scindgraphy and radiotherapy of bone tumors.

Hydrogenation Properties of Zr Films Under Various Conditions of Hydrogen Plasma

The hydrogenation properties of Zr samples with and without an Ni overlayer under various plasma conditions were investigated by means of non-Rutherford backscattering and elastic recoil detection analysis. The theoretical maximum hydrogen capacity, 66.7 at%, could be achieved at a hydrogen absolute pressure of ~2 Pa and a substrate temperature of ~393 K for a plasma irradiation of only 10 min; this was significantly greater than that for gas hydrogenation under the same hydrogen pressure and substrate temperature. It was also found that the C and O contamination on the sample surface strongly influences the hydrogenation, and that the maximum equilibrium hydrogen content drops dramatically with the increasing total contamination. In addition, the influence of the Ni overlayer on the plasma hydrogenation is discussed.