Micro-CT Imaging of RGD-Conjugated Gold Nanorods Targeting Tumor In Vivo

Gold nanomaterials as computed tomography (CT) contrast agents at lower X-ray dosage to get a higher contrast have advantages of longer imaging time and lower toxic side effects compared to current contrast agents. As a receptor for Cyclo (Arg-Gly-Asp-D-Phe-Lys) (RGD) peptide, integrin αvβ3 is overexpressed on some tumor cells and tumor neovasculature. In this paper, we conjugated the RGD peptide on the surface of gold nanorods (AuNRs), designated as RGD-AuNRs, a promising candidate in applications such as tumor targeting and imaging capability for micro-CT imaging. Integrin αvβ3-positive U87 cells and integrin αvβ3-negative HT-29 cells were chosen to establish animal models relatedly and then texted the tumor targeting ability and imaging capability of RGD-AuNRs in vitro and in vivo. The MTT assay and stability measurement showed that RGD-conjugation eliminated their cytotoxicity and improved their biocompatibility and stability. Dark-field imaging of U87 cells and HT-29 cells testified the binding affinities and uptake abilities of RGD-AuNRs, and the results showed that RGD-AuNRs were more specifical to U87 cells. The enhanced micro-CT imaging contrast of intramuscular and subcutaneous injection illustrated the feasibility of RGD-AuNRs to be contrast agents. Furthermore, the micro-CT imaging of targeting U87 and HT-29 tumor models verified the targeting abilities of RGD-AuNRs

Synoptic conditions and radar characteristics for elevated thunderstorm during a snowstorm event in Henan Province

A snowstorm event followed by the elevated thunderstorm occurred in Henan Province from February 24 to 25 in 2021. The operational forecast of all meteorological stations failed to capture the thunderstorm of this event, with the snowfall being underestimated. Using the conventional meteorological observations, the dual polarization weather radar products, and the NCEP/NCAR reanalysis with special resolution of 1° and temporal resolution of 6 h, we conducted the analysis of the synoptic conditions and the characteristics of the dual polarization radar parameters for the elevated thunderstorm during this event. Results are as follows. (1) Due to the interaction of synoptic scale systems such as the mid-latitude upper trough moving eastward and deepening, the southwest jet developing northward at 700 hPa, and the cold air diffusing southward from the surface, the convection is triggered, which resulted in the elevated thunderstorms during the snowstorm event. (2) The strongest water vapor transport is located at 700 hPa, the great value belt of water vapor flux is located in the region along the Yellow River in Henan, and there is the abundant water vapor over Henan in this event, which provide favorable thermodynamic condition for the establishment of unstable stratification in the middle level and the triggering of convection. (3) The superposition of upward branches of two secondary circulations in front of the trough provides strong upward motion for the occurrence of thunderstorms and the maintenance of snowfall. The strong vertical wind shear at 0-6 km is beneficial to the development of symmetric instability. The instability energy in the mid-and upper-level is released due to the convergence of southwest wind jet at 700 hPa and the large-scale forcing by the upper trough, thus triggering convection. (4) When the elevated thunderstorm occurs, the intensity of radar echo is greater than or equal to 45 dBz and its top height is over -20 ℃. The "bull's eye" structure and maintain of the convergence rising area are favorable for generating the thunderstorm. The main characteristics of dual polarization radar parameters during the elevated thunderstorm are that the correlation coefficient (CC) is low of 0.7-0.9, the specific differential phase (KDP) is high of 0.5°- 0.7°·km-1, and the differential reflectivity factor (ZDR) is more than 2 dB. Echo intensity over 55 dBz with large KDP of 0.5°-0.7°·km-1 corresponds to the period of frequent lightning and heavy snowfall

Effect of Silicon Addition on High-Temperature Solid Particle Erosion-Wear Behaviour of Mullite-SiC Composite Refractories Prepared by Nitriding Reactive

Solid particle erosion-wear experiments on as-prepared mullite-SiC composite refractories by nitriding reactive sintering were performed at elevated temperatures, using sharp black SiC abrasive particles at an impact speed of 50 m/s and the impact angle of 90° in the air atmosphere. The effects of silicon powder addition and erosion temperature on the erosion-wear resistance of mullite-SiC composite refractories were studied. The test results reveal that Si powders caused nitriding reaction to form β-sialon whiskers in the matrix of mullite-SiC composite refractories. The erosion-wear resistance of mullite-SiC composite refractories was improved with the increase of silicon powder addition and erosion temperature, and the minimum volume erosion rate was under the condition of 12% silicon added and a temperature of 1400°C. The major erosion-wear mechanisms of mullite-SiC composite refractories were brittle erosion at the erosion temperature from room temperature to 1000°C and then plastic deformation from 1200°C to 1400°C