Abstract Objectives: To investigate the diagnostic performance of single-source dual-energy computed tomography (DECT) based on gemstone spectral imaging technology (including Discovery CT750HD and Revolution CT) in patients with suspected feet/ankles gouty arthritis, and evaluate the urate deposition with a novel semi-quantitative DECT scoring system. Methods: A total of 196 patients were consecutively included. Feet and ankles were evaluated in all patients by single-source DECT scan. The 2015 EULAR/ACR criteria were used as the reference for the diagnosis of gout. The sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) of DECT for the diagnosis of gout in the early (≤1 year), middle (1-3 years), and late (> 3 years) disease durations were calculated. Besides, a novel semi-quantitative DECT scoring system was assessed for the measurement of urate deposition, and the correlation between the scores and the clinical and serological data were also evaluated. Moreover, the influences of artifacts on the diagnostic performance of DECT were also determined. Results: The sensitivity, specificity, and AUC of DECT in 196 patients were 38.10, 96.43%, and 0.673 in the early-stage group; 62.96, 100.00%, and 0.815 in the middle-stage group; and 77.55, 87.50%, and 0.825 in the late-stage group, respectively. The overall diagnostic accuracies in the AUC of DECT (Discovery CT750HD and Revolution CT) in the middle and late stages of gout were higher than that in the early stage of gout. Besides, the monosodium urate crystals were deposited on the first metatarsophalangeal joints and ankles/midfeet. Age, the presence of tophus, bone erosion, and disease duration considerably affected the total urate score. No statistical difference in the positive detection of nail artifact, skin artifact, vascular calcification, and noise artifact was found between the case and control groups. Conclusion: DECT (Discovery CT750HD and Revolution CT) showed promising diagnostic accuracy for the detection of urate crystal deposition in gout but had limited diagnostic sensitivity for short-stage gout. Longer disease duration, the presence of tophus, and bone erosion were associated with the urate crystal score system. The artifacts do not remarkably affect the diagnostic performance of DECT in gout.

The microstructures of high-Si Al alloy cylindrical simples produced by rheological squeeze-casting with bottom-up filling were investigated. The effect of process parameters on the distribution of hard phases (primary Si and Fe-rich phase) was evaluated, and flow characteristics of semi-solid slurry of high-Si Al alloy were investigated. Differences in volume fractions (VFs) of hard phases between the middle and upper layers of cylindrical samples decreased as the squeezing speed increased. Moreover, the flow state of the semi-solid alloy slurry transitioned from laminar to turbulent flow as the squeezing speed was increased. Movement of gases throughout the semi-solid alloy slurry filling process was analysed under different process parameters. The results provide insights for improving rheological casting of high-Si Al alloy and other Al matrix composites.

Three different compositions of high-Si Al alloy pipe, with a gradient structure, were produced through semi-solid rheological squeeze casting, the microstructural characteristics of which were investigated. The mechanism of gradient structure formation and the effect of acicular Fe-rich phases on liquid segregation were revealed. Meanwhile, the crystal structures of the Al4FeSi2 and Al15(Fe, Mn)3Si2 phase were elucidated. The relationship between the volume fraction of hard particles in the pipe wall and the macro-hardness was established. Wear resistance tests of the inner surfaces of the pipe walls, and tensile strength tests at different positions around the pipe walls, showed that the δ-Al4FeSi2 phase (acicular Fe-rich phases) reduced the wear resistance and the tensile strength of the alloy. In this study, the gradient distribution of the hard particles caused the outside of the pipe wall to have a higher tensile strength.

The influence of homogenization treatment on microstructure evolution of Mg-5.8Zn-0.5Zr-1.0Yb (mass fraction, %) alloy was investigated under different annealing temperatures and holding times. Results indicated a severe dendritic segregation in the as-cast ingot. Zn and Yb segregate remarkably at the grain boundary and Zr appears in the form of precipitates. The Mg-Zn binary eutectic phases and a new ternary phase Mg-Zn-Yb are mainly distributed at dendrite boundaries. After homogenization, most of the eutectic phases dissolve into the matrix, except for a small amount of Mg-Zn-Yb phase. The area fractions of residual secondary phase decrease from 5.54% in the as-cast alloy to 0.59% in the well-homogenized sample. Microhardness test indicates that with the increasing temperature and holding time, microhardness value decreased sharply within the first stage of homogenization and then increased steadily to the local maximum value at 380 ºC and 12 h, followed by a slight reduction. Basing on the comprehensive analysis on microstructure and mechanical properties, the homogenization treatment at 380 ºC for 12 h is preferable.

The purpose of this work was to investigate the isolation, culture process of chicken gonadal primordial germ cells (PGCs) and study their biological characterization. PGCs were harvested from 5.5-day-old chicken embryonic genital ridges and explanted onto chicken embryonic fibroblasts (CEFs). The results showed that the primary cultivation of chicken PGCs on their own gonadal stroma cells were better than CEFs at first two days for reproduction. The conditioned media supported the growth and colony formation of PGCs for a prolonged time in vitro and maintained a normal diploid karyotype, which were positively stained by alkaline phosphatase (AKP), periodic acid Schiff (PAS) and reacted with anti-SSEA-1, SSEA-3, Oct4, Blimp1 and Sox2. Real-time PCR showed that they expressed the stage specific genes CVH, Blimp1 and Dazl, the stem cell specific genes Sox2, Pouv and Nanog. They also formed the embryoid bodies (EBs). These results suggested that the chicken PGCs cultured in vitro not only had strong self-renewal ability, but also had the potential capability of multi-lineage differentiation.