Quasi-isentropic compression of LiH above 400 GPa using magnetocumulative generator.

The knowledge of high-pressure behavior of LiH is significant for the validation of fundamental theoretical models and applications in thermonuclear materials and potential energy supplies. The compressibility of 7LiH under isentropic compression at high pressure was investigated experimentally and theoretically. The experimental technique for quasi-isentropic compression with low-density materials was developed using the magnetocumulative generator CJ-100 and x-ray flash radiography. The x-ray images and extracted interface of the sample target in dynamic flash radiography experiments were obtained. According to each interface size of the target both before and after compression, the compression ratio of 7LiH and reference material aluminum was obtained. The density of the reference and using its known isentropic curve provide the pressure in the reference. The pressure in 7LiH was deduced from the pressure in the reference and using the calculated gradient correction factor. The quasi-isentropic data point at 438 GPa was obtained experimentally. A semiempirical three-term complete equation of state was constructed and validated for 7LiH using the theory of Mie-Grüneisen-Debye with experimental data from the literature. The quasi-isentrope data point is reasonably consistent with the theoretical results. The quasi-isentropic experimental techniques and results broaden the existing research scope and are practical and helpful to further validate theoretical models in the future.

[Quantitative dynamic contrast enhancement MR imaging parameters in the prediction and evaluation of the treatment response of malignant sinonasal tumors to chemotherapy:a preliminary result].

Objective: To investigate the value of quantitative dynamic contrast enhancement MR imaging (DCE-MRI) parameters in the prediction and evaluation of the response to neoadjuvant chemotherapy in patients with malignant sinonasal tumors by comparing the parameter values before and after chemotherapy. Methods: DCE-MRI was performed in 14 patients (6 male cases, 8 female cases, 16-83 years) with malignant sinonasal tumors before chemotherapy in Beijing Tongren Hospital from January 2012 to December 2013 in which DCE-MRI was performed in 8 patients on the 7th, 21st and 42nd days after chemotherapy. The values of quantitative parameter including K(trans), K(ep), and V(e) of the tumor were assessed and the change rate of these quantitative parameter values after chemotherapy was calculated. Results: Response to chemotherapy of the tumor was found in 11 patients with malignant sinonasal tumors,whereas no response to chemotherapy of the tumor was confirmed in 3 patients. K(trans) ((0.75±0.28)/min) and K(ep) ((3.23±1.48)/min) values of the tumor before chemotherapy in patients with response to chemotherapy were significantly bigger than those ((0.43±0.41)/min, (1.34±0.42)/min) in patients with no response to chemotherapy (all P<0.01).There was no significant difference in V(e) values between two groups (P=0.165). Compared with K(trans) values of the tumor before chemotherapy,the change rate of K(trans) values decreased more than 40% on the 7th,21st and 42nd days after chemotherapy in the patients with treatment response,whereas the change rate did not decrease significantly in the patients without treatment response. Conclusion: The bigger K(trans) and K(ep) values of the tumor before chemotherapy,the better the treatment response of the tumor to chemotherapy.