In this paper, we experimentally and numerically confirm a planar Mach–Zehnder interferometer (MZI) device for sensing dielectric samples based on a spoof surface plasmon polariton (SSPP) waveguide. The MZI system is constructed using two different ultrathin transmission lines with distinct dispersion units supporting SSPPs. After SSPPs propagate a certain propagation distance, a resonant dip is formed at a specific frequency due to destructive interference, whose displacement enables the SSPP to be modulated by one of the MZI arms loaded with dielectric samples. We investigate how the variations in the permittivity and thickness of dielectric samples affect the sensibility. Through an error analysis between the experimental measurements and numerical calculations, it is demonstrated that the plasmonic sensor based on the MZI has a high precision. The proposed technique is compact and robust and paves a versatile route toward the chip-scale functional devices in microwave circuits.

The Turki Mountain Tomb, one of the three most representative Liao Dynasty tombs, has yielded numerous exquisite gold and silver artifacts during excavation that have drawn global attention for their superb craftsmanship and distinctive ethnic and period characteristics. However, their manufacturing technology had seldom been studied. In this paper, alloy composition analysis and surface microscopic observation were performed on the single-eared octagonal gold cup unearthed from the Turki Mountain Tomb, utilizing portable X-ray fluorescence spectroscopy (p-XRF) and an ultra-depth field microscope. The composition results at different base material locations of the gold cup were similar, with gold content ranging from 84% to 88% and silver content ranging from 10% to 13%. The p-XRF spectra at the exact center of the ring foot, as well as the pearl roundel on the abdominal ridge and rim, showed dominant Au with minor Ag content. Therefore, it could be concluded that the material of the gold cup was made of Au-Ag alloy. Microscopic observation preliminarily revealed that the manufacturing process involved casting, engraving, and welding. The single-eared octagonal gold cup exhibited numerous conspicuous shrinkage cavities, and it was inferred that the gold cup was formed using casting technology. After the cup body, ring foot, and finger pad were cast separately, they were welded together to form the complete gold cup. In addition, green solder and insufficient fusion of welding material were found between the weld seam of the cup body and the ring foot. The exterior surface of the gold cup was adorned with patterns, such as fish-toe circle, upward lotus motif, and pearl roundels. The average diameter of the fish-toe circle was 303 μm. By examining the overlapping conditions of engraving, it could be inferred that the proposed engraving sequence was to engrave the fish-toe circle first, followed by the flower patterns. As a representative of the exquisite artifacts from the Turki Mountain Tomb, the research of the composition and manufacturing technology of the gold cup provides reference data for the scientific analysis of Liao Dynasty gold and silver artifacts.

The Yungang grottoes (5th to 6th centuries AD) were one of the largest and most artistically valuable ancient grotto complexes in China and were a precious World Cultural Heritage site. Influenced by the natural environment and human factors, various deterioration features appeared in the Yungang grottoes. Taking Cave 29 as the research object, field investigations were conducted to analyse the deterioration features and their distribution within Cave 29. To further analyse the formation mechanisms of deterioration features and the preservation conditions, multi-technique testing methods were used. Infrared thermal imager clearly identified hollowing, cracks and surface salt efflorescence zones. Leeb hardness testing on Cave 29’s walls gave average rebound values of 283–308 HLD, all values were lower than the average rebound values of fresh rock (661.4 HLD), indicating weathering-induced surface hardness reduction. Ultrasonic testing showed the east wall had the highest wave velocity (avg. 1928 m/s), indicating the best preservation, while the south wall had the lowest (avg. 1378 m/s), indicating the most severe weathering. Microscopic observations, ion chromatography measurements, and p-XRF were preliminarily determine that CaSO₄ could be preliminary inferred as the dominant soluble salt phase present at this site. All these findings provided scientific data to support preventive protection and scientific conservation.