Multiple microwave frequencies measurement based on stimulated Brillouin scattering with improved measurement range.

We numerically investigate the operational principle and performance of stimulated Brillouin scattering based multiple microwave frequency signals measurement. The unknown signals are processed specially to generate a gain region which is measured by phase modulation to amplitude modulation converting. By sweeping the vector network analyzer, both single and multiple frequencies measurement can be achieved. The loss spectrum generated by one of the pumps is fully compensated by the gain spectrum of the other pump, which increases the measurement range from 2νB to 4νB.

An ultrawide tunable range single passband microwave photonic filter based on stimulated Brillouin scattering.

A single passband microwave photonic filter with ultrawide tunable range based on stimulated Brillouin scattering is theoretically analyzed. Combining the gain and loss spectrums, tuning range with 44GHz is obtained without crosstalk by introducing two pumps. Adding more pumps, Tuning range multiplying with the multiplication factor equaling to the total quantity of pump can be achieved, which has potential application in microwave and millimeter wave wireless communication systems.

Optimization of transverse emittance for RF-driven negative hydrogen ion source developed at China Spallation Neutron Source.

The China Spallation Neutron Source project Phase-II aims to deliver 500 kW beam power to the spallation target. To meet the beam power requirement, an RF-driven negative hydrogen ion source with an external-antenna has been developed. In order to optimize the beam transmission through the radio frequency quadrupole and the downstream linac, the low energy beam transport line needs to be carefully studied and the transverse emittance is focused in this paper. With computational simulation and experimental verification, the emittance growth caused by nonlinear magnetic fields of the solenoid and the residual magnetic fields at the measuring position has been carefully analyzed. The measurement uncertainty of the double-slit scanner has also been quantitatively estimated. Using the same plasma-beam boundary setting, the beam extraction system is also optimized with particle tracking simulation in CST PARTICLE STUDIO.

[Treatment of peri-implant refracture after intramedullary nail fixation for intertrochanteric fractures].

OBJECTIVE: To investigate the occurrence, treatment, and effectiveness of peri-implant refracture after intramedullary nail fixation for intertrochanteric fractures. METHODS: The clinical data of 16 patients with peri-implant refracture after intramedullary nail fixation for intertrochanteric fractures who met the inclusion criteria between April 2014 and November 2019 were retrospectively analyzed. There were 7 males and 9 females with an average age of 78.4 years (range, 65-93 years). The 14 cases of initial intertrochanteric fractures were classified according to the classification of AO/Orthopaedic Trauma Association (AO/OTA): 5 cases of type A1, 7 cases of type A2, and 2 cases of type A3; the other 2 cases were intertrochanteric combined with subtrochanteric fractures (Seinsheimer type Ⅴ). According to the classification of peri-implant refracture which was proposed by Chan et al., there were 10 cases of type 1 (6 cases of type 1A, 3 cases of type 1B, 1 case of type 1C) and 6 cases of type 2 (4 cases of type 2A and 2 cases of type 2B). The average interval between refracture and initial surgery was 14.6 months (range, 1-52 months). The incidence of peri-implant refracture in short nail group (the length of intramedullary nail used in initial surgery≤240 mm) was 1.92% (11/573), while the incidence of long nail group (the length of intramedullary nail used in initial surgery≥340 mm) was 1.66% (5/301), showing no significant difference between the two groups ( χ 2=0.073, P=0.786). The peri-implant refractures were revised with extended intramedullary nail (5 cases) or fixed with additional limited invasive stabilization system (11 cases). RESULTS: The average operation time was 115.8 minutes (range, 78-168 minutes) and the average intraoperative blood loss was 283.1 mL (range, 120-500 mL). One patient died of myocardial infarction at 3 months after operation, and the other 15 patients were followed up 9-46 months (mean, 16.8 months). The peri-implant refractures healed at 14-20 weeks (mean, 16.4 weeks) after operation. There was no complications such as incision infection, nonunion, internal fixator loosening and rupture, screw cutting-out, and the second refracture during the follow-up. At last follow-up, all injured limbs regained walking function, and the Hospital for Special Surgery (HSS) score was 56-92 (mean, 80.2). The results were classified as excellent in 2 cases, good in 10, fair in 2, and poor in 1, with the excellent and good rate of 80%. CONCLUSION: Stress concentration at the tip of initial intramedullary nail and distal interlocking screw aera is the main cause of peri-implant refracture after intramedullary nail fixation for intertrochanteric fractures. Revision with extended intramedullary nail or fixation with limited invasive stabilization system according to the length of initial intramedullary nail and the type of refracture can get satisfactory effectiveness.