On 3 January 2019, the Chang'e‐4 (CE‐4) touched down on the Von Karman crater located inside the South Pole‐Aitken Basin, providing for the first time the opportunity for in situ measurements of the lunar regolith at the farside of the Moon. The CE‐4 ground penetrating radar reveals that fine‐grained regolith, coarse impact ejecta, and fractured bedrocks lie beneath the exploration path of the Yutu‐2 rover. The variations of regolith permittivity with depth and the radargrams indicate that the CE‐4 site has a fine‐grained regolith layer thickness of 11.1 m, which is about 1.3–3 times higher than the in situ measurement results at the Apollo and Chang'e‐3 (CE‐3) sites except for Apollo 16, possibly due to a faster weathering rate of ejecta deposits compared with coherent basalt substrates. The penetration depth of CE‐4 is about 2.85 times (in terms of round‐way delay) deeper than CE‐3, probably due to the differences in abundances of ilmenite and rocks in the regolith.

The unequal distribution of volcanic products between the Earth-facing lunar side and the farside is the result of a complex thermal history. To help unravel the dichotomy, for the first time a lunar landing mission (Chang’e-4, CE-4) has targeted the Moon’s farside landing on the floor of Von Kármán crater (VK) inside the South Pole-Aitken (SPA). We present the first deep subsurface stratigraphic structure based on data collected by the ground-penetrating radar (GPR) onboard the Yutu-2 rover during the initial nine months exploration phase. The radargram reveals several strata interfaces beneath the surveying path: buried ejecta is overlaid by at least four layers of distinct lava flows that probably occurred during the Imbrium Epoch, with thicknesses ranging from 12 m up to about 100 m, providing direct evidence of multiple lava-infilling events that occurred within the VK crater. The average loss tangent of mare basalts is estimated at 0.0040-0.0061.

The purpose of this study was to describe radiologic anatomy of the left atrium diverticulum. There were 20 patients with 27 left atrium diverticulums in 120 consecutive patients who underwent CT of coronary angiography. The presence probability of left atrium diverticulum was 16.7%, male of it was 13.0%, female was 17.6%. There was no difference on gender (P > 0.05). There were four patients accompanying with variation of pulmonary vein at one time. The diverticulum might be single or multiple, cystiform or tubiform. It could locate anterior wall or posterior wall or superior wall of left atrium. Left atrium diverticulums which was single, cystiform, and located in anterior wall were common. The cervix width of diverticulum was 4.9 +/- 3.2 mm, the body height of them was 5.4 +/- 2.0 mm. The ratio of body height to cervix width was from 0.47 to 4.08 (median 1.16). Ten patients of them undertook cardiac ultrasound examination at same time. There were five patients who left atrial diastolic function decreased, four patients who left ventricular systolic function decreased. Three of them both existed left atrial diastolic function decreasing and left ventricular systolic function decreasing, accompanied with mitral or aortic regurgitation. No patient was found that left atrium pressure or left ventricle diastolic pressure was increasing. The left atrium diverticulums of ten patients were probably congenital because their hemodynamical status cannot lead to diverticulum formation. It can be proved by reexamination after therapy or autopsy at last. In conclusion, multi-detector row computed tomography could provide anatomy details of left atrium diverticulum to help to finish heart and chest surgery successfully.

Cavities under urban roads have increasingly become a great threat to the traffic safety in many cities. As a quick, effective, and high-resolution geophysical method, ground penetrating radar (GPR) has been widely used to detect and image near-surface objects. However, the interpretation of field GPR data is still challenging. For example, it is hard to distinguish reflections caused by road cavities or other urban utilities by a conventional 2D GPR survey. The superiority of 3D GPR in data interpretation is demonstrated by a laboratory experiment. Two pipes and a glass-made cavity buried in a sandpit show similar hyperbolic reflections in the 2D GPR profiles, and are hard to be discriminated. In contrast, their geometric shapes and dimensions are readily identified in the 3D image reconstructed from the synthetic 3D GPR dataset. Thus, a car-mounted 3D GPR system with two antenna arrays oriented in different polarization directions is developed, and has detected over 100 cavities in three Chinese cities over the past one year. The field data of two of the cavities are presented. As a result, the cavity depth, horizontal size and height can be accurately estimated from the 3D GPR dataset. Both laboratory and field experimental results indicate that 3D GPR possesses a great potential in detection and recognition of road cavities and utilities in the complicated urban environment.