A method for reducing thermal injury during the ureteroscopic holmium laser lithotripsy

Objective:Many studies have demonstrated the heat effect from the holmium laser lithotripsy can cause persistent thermal injury to the ureter.The purpose of this study was to elucidate the use of a modified ureteral catheter with appropriate firing and irrigation to reduce the thermal injury to the“ureter”during the ureteroscopic holmium laser lithotripsy in vitro.Methods:An in vitro lithotripsy was performed using a modified catheter(5 Fr)as the entrance for the irrigation and the holmium laser fiber while using the remaining space in the ureteroscopic channel as an outlet.Different laser power settings(10 W,20 W,and 30 W)with various firing times(3 s,5 s,and 10 s)and rates of irrigation(15 mL/min,20 mL/min,and 30 mL/min)were applied in the experiment.Temperature changes in the“ureter”were recorded with a thermometer during and after the lithotripsy.Results:During the lithotripsy,the local highest mean temperature was 60.3℃ and the lowest mean temperature was 26.7℃.When the power was set to 10 w,the temperature was maintained below 43℃ regardless of laser firing time or irrigation flow.Regardless of the power or firing time selected,the temperature was below 43℃ at the rate of 30 mL/min.There was a significant difference in temperature decrease when continuous 3 s drainage after continuous firing(3 s,5 s,or 10 s)compared to with not drainage(p<0.05)except for two conditions of 0.5 J×20 Hz,30 mL/min,firing 5 s,and 1.0 J×10 Hz,30 mL/min,firing 5 s.Conclusion:Our modified catheter with timely drainage reducing hot irrigation may significantly reduce the local thermal injury effect,especially along with the special interrupted-time firing setting during the simulated holmium laser procedure.

Application of controlled-release urea increases maize N uptake,environmental benefits and economic returns via optimizing temporal and spatial distributions of soil mineral N

The creation of controlled-release urea (CRU) is a potent substitute for conventional fertilizers in order to preserve the availability of nitrogen (N) in soil,prevent environmental pollution,and move toward green agriculture.The main objectives of this study were to assess the impacts of CRU’s full application on maize production and to clarify the connection between the nutrient release pattern of CRU and maize nutrient uptake.In order to learn more about the effects of CRU application on maize yields,N uptake,mineral N (N_(min)) dynamics,N balance in soil-crop systems,and economic returns,a series of field experiments were carried out in 2018–2020 in Dalian City,Liaoning Province,China.There were 4 different treatments in the experiments:no N fertilizer input (control,CK);application of common urea at 210 kg ha^(-1)(U),the ideal fertilization management level for the study site;application of polyurethane-coated urea at the same N input rate as U (PCU);and application of PCU at a 20% reduction in N input rate (0.8PCU).Our findings showed that using CRU (i.e.,PCU and 0.8 PCU) may considerably increase maize N absorption,maintain maize yields,and increase N use efficiency (NUE) compared to U.The grain yield showed considerable positive correlations with total N uptake in leaf in U and 0.8 PCU,but negative correlations with that in PCU,indicating that PCU caused excessive maize absorption while 0.8 PCU could achieve a better yield response to N supply.Besides,PCU was able to maintain N fertilizer in the soil profile 0–20 cm away from the fertilization point,and higher N_(min)content was observed in the 0–20 cm soil layer at various growth stages,particularly at the middle and late growing stages,optimizing the temporal and spatial distributions of N_(min).Additionally,compared to that in U,the apparent N loss rate in PCU was reduced by 36.2%,and applying CRU (PCU and 0.8 PCU) increased net profit by 8.5% to 15.2% with less labor and fertilization frequency.It was concluded that using CRU could be an effective N fertilizer management strategy to sustain maize production,improve NUE,and increase economic returns while minimizing environmental risks.