Study of photo-ionization and thermal effects on the interaction of a nanosecond extreme ultraviolet laser with copper.

The damage mechanism of a nanosecond extreme ultraviolet (EUV) laser with solid targets is complex and involves thermal and nonthermal effects. In this study, the interaction process of a nanosecond 46.9 nm laser with copper was investigated. A Faraday cup was used to measure the electron signals induced by the laser irradiation. The photo-ionization and thermal effects in the interaction process are discussed according to the results.

Efficiency and safety of traditional growing rod technique in the treatment of early onset dystrophic scoliosis secondary to type 1 neurofibromatosis with intraspinal rib head in children / 中华骨科杂志

Objective:To investigate the efficiency and safety of traditional growing rod in the treatment of early onset dystrophic scoliosis secondary to type 1 neurofibromatosis (NF1-DS) with intraspinal rib head in children.Methods:From September 2006 to May 2020, this study recruited 20 children with intraspinal rib head with early onset NF1-DS who had received traditional growing rods. There were 13 boys and 7 girls and the age of the initial operation was 7.0±1.6 years (range, 4.1-9.8 years). There were 7 cases of simple left chest bend, 9 cases of simple right chest bend, and 4 cases of double chest bend; 13 patients had varying degrees of kyphosis deformity. Two children had neurological symptoms before surgery, American Spinal Injury Association Impairment Scale (AIS) were grade D. The proportion of the intraspinal rib head (IRP), the Cobb angle of the main chest bend, apical vertebra rotation (AVR), apical vertebral translation (AVT), trunk shift (TS) and sagittal TK, lumbar lordosis (LL), sagittal balance and T 1-S 1 height were measured before and after first time internal fixation and at last follow-up, and the complications were also evaluated. Results:All 20 patients were followed up and the average follow-up time was 41.6±23.8 months (range, 24-99 months). A total of 85 operations was conducted including 63 protrude operations. After operation, the IRP was significantly lower than that before operation (preoperative 33.1%±17.5% vs. postoperative 22.2%±11.3%, P<0.001) and no significant correction loss was found at last follow-up 23.7%±12.4% ( P>0.05). The mean Cobb angle decreased from 75.9°±26.7° preoperatively to 45.0°±18.5° postoperatively ( P<0.001) and there was still significant improvement at the last follow-up (41.0°±17.2°) compared with postoperatively ( P<0.05). The AVR was significantly reduced after surgery compared with preoperatively (33.0°±10.1° vs. 39.3°±13.3°, P<0.001), and the last follow-up (40.1°±11.4°) was significantly improved compared with postoperative ( P=0.005). The T 1-S 1 height increased from 259.8±70.7 mm preoperatively to 296.9±78.4 mm postoperatively ( P=0.001), and at the last follow-up 296.9±78.4 mm was still significantly higher than after operation ( P<0.001), with an average annual increase of 12.4±3.2 mm. Significant correction of AVT, TK, LL and sagittal balance were noted after initial surgery ( P<0.05), and no significant correction loss was found at last follow-up ( P>0.05). There were 10 complications in 7 cases. There were 5 complications of pedicle screw loosening, 1 complication of bolt droping, 2 complications of broken rod, 1 complication of distal junctional kyphosis and 1 complication of adding-on phenomenon. 2 cases with nerve injury were recover after operation (AIS grading E). None of the children had new neurological complications during growth rod insertion and multiple stretching during follow-up. Conclusion:For children with early onset NF1-DS with intraspinal rib head, if the preoperative AIS grade is D or E, traditional growing rod technique is relatively safe and effective and can make the intraspinal rib head remove from the spinal canal partly.