[Clinical efficacy of endoscopy in the treatment of lumbar disc herniation combined with posterior apophyseal ring separation].

OBJECTIVE: To investigate the efficacy and safety of total spine endoscopy in the treatment of lumbar disc herniation combined with posterior apophyseal ring separation. METHODS: From January 2015 to January 2018, a total of 21 patients with lumbar disc herniation complicated with posterior apophyseal ring separation were treated with total spine endoscopy via interlamina approach. There were 17 males and 4 females. The age ranged from 18 to 48 years old and the median age was 27 years old. All were single segment unilateral disc herniation, interlaminar approach was adopted, and the herniated disc was removed unilaterally at the symptomatic side under the microscope, and all or part of the broken bonewas removed. RESULTS: There were no complications such as incision infection, intervertebral space infection, intestinal injury, dural injury and cerebrospinal fluid leakage. The operation time ranged from 32 to 92 minutes and the median time was 57 minutes. Postoperative imaging examination showed that 2 patients had complete resection of osteotomy of posterior edge of vertebral body, 16 patients had partially resection and 3 patients had no resection. All intervertebral discs were completely removed. All 21 patients were followed up, and the duration ranged from 12 to 36 months, with a median of 15 months. The VAS of lumbago was 7.10±1.20 before surgery, 3.46±0.23 on the 3rd day after surgery, 2.36±0.19 on the 6th month after surgery; and the VAS of leg pain was 8.80±0.55 before surgery, 3.54±0.28 on the 3rd day after surgery, and 2.59±0.26 on the 6th month after surgery. The Oswestry Disability Index score was (69.71±9.37)% before surgery, (32.19±6.95)% on the 6th month after surgery, and (20.95± 6.16)% at the latest follow up. Onthe 1st year after operation, 16 patients got an excellent result, 4 good and 1 fair according to Macnab evaluation system. CONCLUSION: Total spine endoscopy via interlaminal approach can be used as an option in the treatment of lumbar disc herniation combined with vertebral posterior margin dissociation, which can reduce trauma and injury to the lumbar dorsal muscle and achieve similar decompression effect as open surgery. The long term efficacy needs to be further proved by prospective randomized controlled studies with larger sample size.

[Transformation of Non-point Source Soluble Nitrogen in Simulated Drainage Ditch].

The drainage ditch has a compound ecosystem structure consisting of water, sediment and plants. Migration and transformation of the non-point source solute is important to study interception, control and management of agricultural non-point source pollution in the drainage ditch. Based on the experiment on static simulation of drainage ditches, the article used typical non-point source soluble nitrogen as an example to analyze the changing process of nitrogen content in water, sediment and reeds, and to study the effects of the sediment adsorption and desorption, reeds growth and death in different periods on nitrogen concentration in water. The article discussed nitrogen migration in water-sediment-reeds compound ecosystem and its influence on nitrogen concentration in water. The results showed that both adsorption and desorption in sediment and absorption and assimilation of reeds growth had effect on nitrogen concentration in water. The effect before October was reducing the nitrogen concentration in water, which was the process of nitrogen purification in water. After October, the nitrogen concentration in water increased and made it easy to form secondary nitrogen pollution. Meanwhile, the migration in the water-sediment-seeds ecosystem in simulated drainage ditch had close ties, any migration and transformation of nitrogen in a single medium or between different mediums would cause adjustment of nitrogen concentration in water.

[Distribution Characteristics of Solute Nitrogen in the Water-Sediment of Farmland Drainage Ditch].

Along with the highlighted water environmental issues and the gradual effective renovation of the point source pollution (PSP) such as industrial waste, the agricultural non-point source pollution (AGNSP) caused by the non-scientific application of fertilizers and pesticides has attracted more and more attention. On the basis of strengthening the field "source control", making the best use of agricultural drainage ditch (pond) system "intercepting process" is a vital means of agriculture non-point source pollution control and management at the present stage. Ditch system is not only an important part of the farmland irrigation and drainage engineering, but also a vital corridor of AGNSP of solute transport. The unique farmland drainage ditch water-sediment-plant system in ecology and physics is similar to linear wetland function,and has effect of interception and purification on non-point source solute in farmland drainage. Non-point source solute transformation mechanism of each medium in the farmland drainage ditch water-sediment-plant system is unclear, in view of the current situation, the study took the natural channel as the object. Taking the non-point source solute nitrogen as an example, by field monitoring test during March 2014-February 2015, the distribution characteristics of non-point solute nitrogen in the water-sediment of the farmland drainage ditch were analyzed. The results indicated that the concentration of total nitrogen in water and the total nitrogen content in the sediment of the experimental ditches both showed a certain degree of decreasing trend along the longitudinal ditch, which represented a purification effect of the ditch system on the non-point source solute. The concentration of total nitrogen in water and the total nitrogen content in the sediment had big inhomogeneity in the ditch cross-sectional distribution, and its distribution characteristics were related to the shape of the cross-section, flow variation process, flow velocity distribution and other factors. The balance of the total nitrogen concentration was 76.89%, and the total nitrogen content in the sediment was 57.04%. During the trial period, the total nitrogen concentration in the water was "concave" shape, while in the sediment it was "convex" shape, showing opposite changing trends.

[Simulation and application of the agricultural non-point source pollutants in drainage ditch].

Drainage ditch system is the transitional zone between yield in the field and receiving waters for agricultural non-point source pollutants. Based on the brief analysis of the migration and transformation process of agricultural non-point source pollutants in drainage ditch system, the one-dimensional transport model of agricultural non-point source pollutants in drainage ditch system was constructed on the basis of the equation of continuity of flow and pollutants migration transform. Taking the Di Yi drainage ditch system, in the Qing-Tong-Xia irrigation district at the Yellow River upstream, as an example, combining with actual situation, the drainage discharge and concentration of nitrate nitrogen and total phosphorus were simulated by this model. The results show that the simulated drainage discharge accords with measured data approximately and Nash-Suttcliffe coefficient is 0.82, the simulated concentration of nitrate nitrogen and total phosphorus in farmland drainage was reasonable.

[Establishment and application of the estimation model for agricultural non-point source pollution in the field].

The quantitative research on pollution loads is the basis of control, evaluation and management of non-point source pollution. The estimation of agricultural non-point source pollution loads includes two steps: evaluation of water discharge and prediction of pollutant concentration in agricultural drain. Water discharge was calculated by DRAINMOD model based on the principle of water balance on farmland. Meanwhile, the synthesis of fertilization and irrigation is used as an impulse input to the farmland, the pollutant concentration changes in agricultural drain is looked as the response process corresponding to the impulse input, the complex migratory and transforming process of pollutant in soil are expressed implied by Inverse Gaussian Probability Density Function. Based on the above, the estimation model of agricultural non-point source pollution loads at field scale was constructed. Taking the typical experimentation area of Qingtongxia Irrigation District in Ningxia as an example, the loads of nitrate nitrogen and total phosphorus in paddy-field drain was simulated by this model. The results show that the simulated accorded with measured data approximately and Nash-Suttcliffe coefficient is 0.963 and 0.945 respectively.