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Nitrogen use efficiency (NUE) has received worldwide concern in the sphere of agronomic science and environmental science, and it is fundamentally important for evaluating N utilization status and optimizing N fertilization management in cultivated lands. In recent years, in consideration of low values and great variations of NUE in China's cultivated lands, some scholars have discussed on the traditional concept and calculating method of NUE, and also have proposed some substituted NUE calculating methods. In this paper, we summarized some disadvantages of both conventional concept and calculating method of NUE, i.e. the subtraction method and the 15N labeling method. Furthermore, we particularly introduced several substituted NUE calculation methods and discussed research directions in the future. In summary, we strongly suggested the establishment of a comprehensive evaluation index system of N utilization in good accordance with the current agricultural production status in China, based on a correct understanding of the dialectical relationships among N application rate, crop yield, N utilization and N loss. [ABSTRACT FROM AUTHOR]

In order to study the anti-explosion capacity of nonmetallic material, explosion of shelled explosive was analyzed theoretically, and a method to determine the protective radius was proposed. The protective radius of damage and protective radius of expansion were both considered. The explosion experiments were carried out to validate the anti-explosion capability of new type safety equipment. Both overpressure of the explosion shock and noise were measured. The experiment results demonstrate that the new type safety equipment has better performances in attenuating shock and noise. [ABSTRACT FROM AUTHOR]

Objective: To observe the clinical effect of ceramic on ceramic total hip arthroplasty(THA)in Crowe IV developmental dysplasia of the hip(DDH)., Methods: From April 2008 to December 2015, 137 hips of 111 Crowe IV DDH patients received THA using Forte or Delta ceramic on ceramic by one senior surgeon, which consists of 85 unilateral hips and 26 bilateral hips. The average age of the patients was(38.88±10.83) years old ranging from 18 to 68 years old. The mean follow-up was(41.16±21.50) months ranging from 12 to 96 months. All the patients were evaluated by Harris Hip Score. Radiographic evaluations were made preoperatively and during follow-up. Harris scores, the incidence of complications such as ceramic fracture, squeaking, dislocation were observed., Results: The mean preoperative Harris score was 56.54±15.67, the mean postoperative Harris score was 88.30±6.86( P =0.017). Periprosthetic osteolysis was not deteced around any cup. No ceramic fracture occurred. There were 3 cases of revision surgery due to infection, losening of the stem and limb length discrepancy, respectively; 3 cases of dislocation occurred. Seventy-seven patients were recorded the gait and the hip mobility, the hip flexion of 69 patients were above 120 degrees., Conclusions: Ceramic on ceramic bearing showed an encouraging result in Crowe IV DDH total hip arthroplasty., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© 2018 by the China Journal of Orthopaedics and Traumatology Press.)

Objective: To study the complications and efficacy of self-made, antibiotic-loaded cement articulating spacers in the treatment of the infected hip replacement., Methods: Between January 2006 and July 2016, 265 patients (266 hips) received a self-made, antibiotic-loaded cement articulating spacer as part of a two-stage protocol. Among those patients, there were 143 males(144 hips) and 122 females(122 hips). The cement articulating spacers with vancomycin and two Steinman pins were made by a self-made mold system. Meanwhile, another antibiotic was added to the spacers according to the drug sensitivity test. Record if the infected prosthesis was removed, related complication with spacer(breakage and dislocation), Harris score, and control rate of infection., Results: The mean age of two-stage revision operation was(57.4±14.2) years. Thirty-nine patients(14.7%) used extended trochanteric osteotomy(ETO) to remove the infected prosthesis. And 38 patients occurred mentioned complications(14.3%). Spacer breakage occurred in 28 cases(10.5%) and dislocation occurred in 10 cases(3.8%). The mean follow-up time was(83.4±14.6) months. The Harris hip score was from 47.56±14.23 preoperatively to 86.43±12.84 at final follow-up( P <0.05). The infection of 256 cases(96.6%) got control after revision operation. However, during postoperative follow-up, 4 cases occurred re-infection, and they were reoperated, and the infections obtained effective control after the operation. Thus total infection control rate was 95.1%(252/265)., Conclusions: Antibiotic-loaded cement articulating spacer made by a self-made mold system is effective in controling infection caused by hip replacement. Related complication is less with spacer by a mould enclosing two Steinman pins. Using metallic internal fixation or allograft bone combined with spacer does not affect infection control., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose.

Objective: To investigate and the clinical effect of S-ROM modular stem in femur reconstruction in hip revision arthroplasty., Methods: From January 2008 to January 2016, 21 patients received revision hip arthroplasties using S-ROM stems. There were 5 males and 16 females with an average of 48.33 years old(range, 29 to 73 years old). There were 13 cases caused by aseptic loosening, 4 cases by infection, 2 cases by nonunion of sub-tuberosity osteotomy, 1 case for repeated dislocation, 1 case for traumatic great trochanter fracture. Primary THA reasons:12 cases for DDH(9 cases for Crowe IV), 5 cases for femoral neck fracture, 2 cases for necrosis of femoral head, 2 cases for proximal femoral deformity caused by early infection. The femur bone defects included Paprosky II in 11 cases, IIIa in 9, and IIIb in 1. Harris hip score , pain score and hip flexion were recorded before and after operation. The subjective satisfaction was recorded at the last follow-up., Results: The operation time and blood loss were 189 min(125 to 290 min) and 867 ml (200 to 2 000 ml). At the final followup, the pain score improved from (17.14±9.56) points preoperatively to (41.71±2.03) points ( t =11.42, P =0.00). The function score improved from (24.01±11.02) points preoperatively to (49.95±5.38) points ( t =9.73, P =0.00). Harris hip score improved from (41.15±14.81) points preoperatively to(91.67±5.83) points( t =15.33, P =0.00). The degree of hip flexion increased from (93.10±27.27) points preoperatively to (121.90±16.62) points at the last follow-up ( t =4.59, P =0.00). The mean subjective satisfaction was 9.48(10 points system), 14 of which were completely satisfactory. The last follow-up hip X-ray showed 21 cases of bone ingrowth, and other femoral stem without loosening or sinking sign significantly. There were 5 cases with bone anchor syndrome around proximal femoral cuff. There were 5 cases of proximal femur fracture, 3 cases of lesser trochanter fracture, 2 cases of greater trochanter fracture intra-operatively. Due to femoral canal stenosis, there were 4 cases of pre-tied wire at lesser trochanter to prevent fractures. There was 1 case of traumatic femoral fracture around stems with a distal oblique fracture, open reduction and locking plate fixation was performed. Other patients had no nerve stretch injury, dislocation, infection and lower limb deep vein thrombosis and other complications at the final follow-up., Conclusions: S-ROM prosthesis has satisfactory results in hip revision arthroplasty with Paprosky II and III femoral defects. Especially for patients with Crowe IV DDH and other proximal femoral deformities, it is possible to adapt to the medullary cavity morphology. Excellent initial stability, less complications and long-term biological fixation can be achieved with S-ROM in femur revision., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose.

Objective: To study the characteristics and clinical effect of total hip arthroplasty(THA) for osteoarthritis and (or) avascular necrosis of femoral head after failure of internal fixation of acetabular fracture., Methods: From February 2009 to October 2014, 31 patients (31 hips) with hip traumatic osteoarthritis and (or) femoral head avascular necrosis after failure of internal fixation of acetabular fracture were treated with THA including 26 males and 5 females, who injured when the average age of(41±12) years. THA were performed, and the duration ranged from 3 to 132 months with a mean of(20.6±26.9) months secondary to traumatic osteoarthritis and(or) femoral head avascular necrosis. All THA were performed with posterior-lateral approach. The postoperative complications were observed. VAS and Harris hip scores were compared pre-operation and post-operation., Results: Twenty-seven cases were followed up, and the duration ranged from 12 to 80 months with a mean of (43.2±11.7) months. One patient had infection around prosthesis. Aseptic loosening occurred in 1 patient, dislocation of prosthesis in 1 patient. No sciatic nerve injury occurred. Hip function and gaits were obviously improved. To the last follow-up, VAS score was decreased from 7.6±1.2 pre-operatively to 1.2±0.9 post-operatively, while the Harris score was improved from 45.5±13.6 pre-operatively to 88.5±7.8 post-operatively, both differences were statistically significant( P <0.01). The post-operative ROM of hip was significantly improved compared to pre-operative ROM( P <0.05), in addition to extension motion. X-ray showed all the acetabular cups were stable, one femur stem subsided 3 mm. Heterotopic ossification occurred in 2 cases., Conclusions: Correct dealing with of internal fixation implants, looking out potential infection and reasonable reconstruction of acetabular bone deficiency were the key to the success of THA for osteoarthritis and(or) avascular necrosis of femoral head after failure of internal fixation of acetabular fracture., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose.

Objective: To summarize experience of using screws and cement to rebuild tibial bone defect in primary total knee arthroplasty (TKA) and to discuss the relationship between the number of required screws and the severity of tibial bone defects., Methods: From July 2009 to May 2015, 34 patients (40 knees) with varus knees underwent TKA, and the screw and cement technique was used to rebuild medial tibia plateau during operation. There were 8 males (8 knees) and 26 females (32 knees), and the average age was (65.00 +/- 7.25) years old (ranged,55 to 82 years old). One to 6 screws were used in each case. Extension stems were used in 2 cases (4 and 5 screws was used respectively). The area percentages of the bone defects measured as defect area/tibia plateau area, depth of each defect, the number of screws needed in each case, were all used to determine the relationship between the number of screws and the area percentage in certain depth of bone defect by statistic methods, as well as the relationship between screw number and defect depth., Results: All the patients were followed up and the average duration was 24 months (ranged, 1 to 72 months). The average preoperative HSS score was 43.33 +/- 6.11 (ranged, 32 to 51 scores). Whereas the average postoperative HSS score was 92.15 +/- 4.64 (ranged,83 to 96 scores). The preoperative individual scores including pain, function, activity, nuscle strength, flexion deformity and stability were all improved compared with preoperation,and the differences were statistically significant. All the patients received normal alignment postoperatively, femoraltibial angle was improved from (167.00 +/- 6.39) degrees preoperatively to (175.00 +/- 2.69) degrees postoperatively, the tibial angle was improved from (78.09 +/- 4.51) degrees preoperatively to (88.75 +/- 1.24) degrees postoperatively. Both area percentage and depth of bone defect in a fitting Ologistic model had a significant statistical relationship with the screw number, and a rectangular coordinate system could be formed according to the relationship., Conclusion: Screws and cement technique is a simple, safe and convenient method to rebuild tibial bone defects in primary TKA and its short-term and midterm effect are both reliable. During opera- tion, according to the rectangular coordinate system, the screw number needed in the operation can be inferred form th area and depth of tibia defect, which could have a guiding function in surgery.

Objective: To compare differences between Crowe IV developmental dysplasia of the hip (DDH) with secondary acetabulum and Crowe IV DDH without secondary acetabulum,and determine whether it is necessary to divide Crowe IV DDH into two subtypes., Methods: From June 2007 to May 2015,145 hips of 112 Crowe N patients who underwent total hip arthroplasty (THA) using S-ROM stem were divided into two groups: secondary acetabulum formaton group (group A) and no secondary acetabulum formaton group (group B). In group A,there were 12 females, 96 males,with an average age of (39.38 ± 11.19) years old. In group B, there were 2 females, 35 males, with an average age of (38.19 ± 10.92) years old. All the patients were evaluated by using Harris Hip Score. Radiographic evaluations were made preoperatively and during follow up. The differences between two groups were compared on dislocation height, canal flare index (CFI), subtrochanteric shortening osteotomy (SSTO) usage, pre- and post-operation Harris scores, complications., Results: The dislocation height for group A was (4.74 ± 1.57) cm, while the dislocation height for group B was (3.12 ± 1.15) cm. Significantly difference was detected between two groups. The CFI for group A was 2.69 ± 0.68, while the CFI for group B was 3.42 ± 0.79, and the significantly difference was detected between two groups. Harris scores were totally improved from 58.18 ± 15.67 preoperatively to 91.20 ± 3.79 post-operatively and the difference was significant. Pre-operative Harris scores was 58.1 ± 15.3 in group A, 58.3 ± 16.9 in group B. Post-operative Harris scores was 91.0 ± 4.1 in group A, 91.0 ± 5.1 in group B. No significant difference was found on Harris scores between A and B preoperatively and post-operatively. Complications of 4 cases peri-prosthesis fracture, 4 cases dislocation and 4 cases nerve injury occur in group A; While only one case dislocation and one case nerve injury occur in group B. No statistical significance was detected., Conclusion: Crowe IV DDH with secondary acetabulum is significantly different from Crowe IV DDH without secondary acetabulum on dislocation height and femoral morphology, which causes the different selections of surgical techniques (SSTO usage or not). These important differences in fundamental parameters indicate the necessity to further divide Crowe IV DDH into IVA and IVB two subtypes.

Nitrogen use efficiency (NUE) has received worldwide concern in the sphere of agronomic science and environmental science, and it is fundamentally important for evaluating N utilization status and optimizing N fertilization management in cultivated lands. In recent years, in consideration of low values and great variations of NUE in China' s cultivated lands, some scholars have discussed on the traditional concept and calculating method of NUE, and also have proposed some substituted NUE calculating methods. In this paper, we summarized some disadvantages of both conventional concept and calculating method of NUE, i.e. the subtraction method and the 15N labeling method. Furthermore, we particularly introduced several substituted NUE calculation methods and discussed research directions in the future. In summary, we strongly suggested the establishment of a comprehensive evaluation index system of N utilization in good accordance with the current agricultural production status in China, based on a correct understanding of the dialectical relationships among N application rate, crop yield, N utilization and N loss.