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Large scale Atomic/Molecular dynamic Parallel Simulator (LAMMPS) molecular dynamics simulation software was used to simulate the copper and aluminum atom diffusion and changes of interface during heating and cooling process of copper and aluminum composite panels. The structures of the interface were characterized through scanning electron microscope (SEM), X-ray diffraction (XRD), and transmission electron microscope (TEM), and the mechanical properties were also tested. The simulation results show that the diffusion rate of copper atom is higher than that of aluminum atom, and that the CuAl2 radial distribution function of the interface at 300 K is consistent with that of pure CuAl2 at room temperature. At 930 K, t = 50 ps Cu atoms spread at a distance of approximately four Al lattice constants around the Al layer, and Al atoms spread to about half a lattice constant distance to the Cu layer. The experimental results show that the thickness of the interface in copper&ndash, aluminum composite plate is about 1 &mu, m, and only one kind of CuAl2 with tetragonal phase structure is generated in the interface, which corresponds with the result of molecular dynamics simulation.

BACKGROUND: Preexcitation syndrome could affect terminal QRS vector, which is not emphasized in clinic. In this study, we made a comparison between vectorcardiogram (VCG) before and after ablation to observe the change of terminal QRS vector. Furthermore, the relationship between the change of terminal QRS vector and accessory pathway (AP) as well as the change of initial QRS vector (delta vector) was analyzed. METHODS: Thirty patients who were proved to have a single AP by ablation were included. All patients were divided into seven groups based on the AP location. Comparison between VCG before and after ablation was made to observe the change of terminal and delta vector. The relationship between the change of terminal QRS vector and AP location as well as delta vector was analyzed. RESULTS: (1) All 30 patients had a change in terminal QRS vector (elevation and/or azimuth) in comparison to postablation VCG. (2) The change of terminal QRS vector was related to delta vector and AP location. The agreement and consistency between the change of terminal QRS vector and delta vector were 91.65% and 0.856 (P < 0.01), respectively. CONCLUSIONS: (1) Both initial and terminal QRS vector are affected by the antegrade conduction of AP. The change of terminal QRS vector is related to the AP location and delta vector. (2) The effect of preexcitation syndrome on QRS terminal vector is shown as more intuitive and easy in spatial vector by comparison with electrocardiogram, which is helpful for the diagnosis of atypical preexcitation and localization of AP.

Objectives The objective of this study was to investigate the effects of slow breathing rate on heart rate variability (HRV) and blood pressure variability (BPV) in healthy subjects. Methods 53 healthy volunteers underwent three periods of controlled breathing at 8, 12 and 16 breaths/min. ECG (RR), respiratory and blood pressure signal were continuously and simultaneously recorded. In our study, the influence of the respiration on RRI (RR interval) and BP were observed. Simultaneously, we studied the effects of slow breathing rate on RRI, amplitude of blood pressure oscillation, low-frequency (LF) power, high-frequency (HF) power and LF/HF of HRV and BPV. Then we also corrected the effects of slow breathing rate on respiratory peak shifts. Results RRI and BP cyclical change coincided with the respiratory cycle; As breathing rate reduced, amplitude of RRI and blood pressure oscillation increased, heart rate slowed (P Conclusions Reductions of respiration rate shifted the respiratory peak into the junction of HF and LF or even below LF range. In accordance with this shift, the effects of slow breathing rate on respiratory peak shifts should be corrected when we performed HRV and BPV spectral analysis; Correct spectral analysis demonstrated that slow respiration can cause increase in HF power and decease in LF power and LF/HF. These demonstrated that slow breathing is indeed capable of increasing vagal activities and shifting sympathetic-vagal balance towards vagal activities.

In preexcitation syndrome, initial vector change (delta wave) is highlighted. However, there has been little information concerning terminal QRS vector change. In our study, preexcitation was simulated in the rabbit model by applying electrophysiological technique. Then we further explored the