Endoscopic ultrasound-guided injection of carbon nanoparticles suspension to label rectal cancer before neoadjuvant chemoradiotherapy:a retrospective cohort study

Background:Localization of the primary tumor and ensuring safe distal surgical margins(DSMs)following neoadjuvant chemoradiotherapy(nCRT)are challenging in locally advanced rectal cancers(LARCs).This study investigated the effectiveness of carbon nanoparticles suspension(CNS)for labeling the primary tumor and allowing precise tumor resection after nCRT.Methods:Clinicopathological data of LARC patients who underwent nCRT followed by laparoscopic radical anal preservation surgery at our center between January 2018 and February 2023 were prospectively collected.The patients were divided into the CNS tattooed(CNS)and non-tattooed(control)groups.In the CNS group,CNS was injected in four quadrants on the anal side 1 cm away from the lower tumor margin.DSMs were determined through intraoperative distal rectal examination in the control group and observation of CNS tattoos in the CNS group.DSM lengths and positive DSM rates were compared between the two groups to analyse the feasibility and effectiveness of CNS for labeling LARCs before nCRT.Results:There was no statistically significant difference in the basic demographic data,effectiveness of nCRT,or post-operative recovery rates between the two groups(all P>0.05).In the CNS group,CNS tattoos were observed on the outside of the rectal wall,with an overall efficiency of 87.1%(27/31).The CNS group had fewer positive DSMs and safer DSM lengths(2.73±0.88 vs 2.12±1.15 cm,P=0.012)than the control group(P<0.05).Conclusions:Endoscopic ultrasound-guided injection of CNS tattoos before nCRT could effectively label the LARCs,ensuring safe DSMs during anus-preserving surgeries(Chictr.org.cn No.:ChiCTR2300068991).

Influence of La2O3 addition on nano indentation hardness and residual stress of Stellite 6 coating prepared by plasma cladding

One of the problems limiting the application of Stellite 6 coating is the residual stress resulting in cracks in the coating easily. In order to reduce the residual stress and increase the nano-indentation hardness,La2 O3 was added to Stellite 6 coating in this study, and the influence on the microstructure, nano indentation hardness and residual stress of the coatings were investigated by scanning electron microscopy（SEM） with energy dispersive spectrum（EDS）, X-ray diffraction（XRD） and nano-indentation tester. Results indicate that the addition of La2 O3 leads to the phenomenon that the dendrite is partly transformed into the equiaxed grain, which results in the grain refinement. The nano-indentation hardness of coatings is improved, which is attributed to the fine-grain strengthening and dispersion strengthening effect of La2 O3. With the addition of La2 O3, the residual stress in coatings is decreased significantly. Especially, when the content of La2 O3 is 0.8 wt%, the nano indentation hardness increases by 1.31 times and residual stress decreases to 20 percent, compared with coating without La2 O3.