Kinetic Model for Denitration Reaction Process of Cylindrical Single-Base Gun Propellant.

As a new type of progressive energy release propellant, nitro gradiently distributed propellant (NGDP) was prepared by a denitration reaction between a denitration reagent and the propellant to remove the energy-containing functional group (-O-NO2) from the surface of the propellant. The kinetics of the denitration reaction determines distribution of the nitrate group in the surface layer of NGDP, which further affects the combustion progressivity. In this paper, the kinetic model for the denitration reaction process of the cylindrical single-base gun propellant was studied by the shrinking unreacted core model (SUC model). The energy change of the propellant particles before and after the denitration reaction was used to evaluate the denitration rates, which were used to fit the proposed SUC cylindrical model. The results show that the rate-controlling step of the denitration reaction process is largely dependent on the concentration of the denitration reagent. At low concentrations (the concentration of the denitration reagent was 6%), the denitration reaction process was controlled by the chemical reaction, and the activation energy was found to be 48.40 kJ·mol-1. When the concentration increased (the concentration of the denitration reagent was 15%), the rate-controlling step changed to a solid product layer diffusion control with an activation energy of 84.77 kJ·mol-1. The kinetic models obtained in this study can provide theoretical guidance for the controlled preparation of NGDP with good combustion progressivity.

[Comparison of curative effect between osteochondral mosaic transplantation and micro-fracture in the treatment of knee joint articular cartilage injury].

OBJECTIVE: To compare the clinical outcomes of microfracture and autogenous osteochondral mosaic transplantation in the treatment of knee joint cartilage injury. METHODS: A retrospective analysis of 71 patients with articular cartilage defects on the femoral condyles who were by autogenous osteochondral mosaic transplantation or microfracture from February 2011 to February 2016, and these patients were followed up for at least 2 years. According to the sugical procedures, the patients were divided into two groups. In the microfracture group, there were 33 patients, 20 males and 13 females, with a mean age of(28.1±4.2) years old; in the mosaicplasty group, there were 38 patients, 26 males and 12 females, with a mean age of(27.8±3.5) years old. The Lysholm knee score, Hospital for Special Surgery (HSS) knee score and the Ahlbäck classification grade were recorded to evaluate the clinical efficacy. Complications were also recorded. RESULTS: The mean Lysholm scores of the microfracture group and the mosaicplasty group improved from 62.9±6.8 and 60.3±7.5 preoperatively to 77.0±5.4 and 85.8±5.6 post-operatively, respectively(P<0.05). Mean HSS scores of the microfracture group and the mosaicplasty group improved from 81.5±7.6 and 79.6±8.6 preoperatively to 88.0±4.7 and 91.9±4.7 post-operatively, respectively(P<0.05). The mean Lysholm score and HSS score were significantly higher in the mosaicplasty group than those in the microfracture group at the latest follow-up. One patient in the mosaicplasty group suffered superficial wound infection. During the follow-up, no knee osteoarthritis was observed in two groups. CONCLUSIONS: Autogenous osteochondral mosaicplasty and microfracture are proved to be safe and effective procedures for knee articular cartilage defects. However, the mosaicplasty has better clinical outcome than the microfracture.

[Percutaneous transforaminal endoscopic discectomy via lateral position assisted with local anesthesia for lumbar disc herniation in elder with systemic diseases].

OBJECTIVE: To explore the clinical effect of percutaneous transforaminal endoscopic discectomy via lateral position assisted with local anesthesia for lumbar disc herniation in elder with systemic diseases. METHODS: The clinical data of 44 elder patients with lumbar disc herniation and systemic diseases treated from June 2013 to June 2017 were retrospectively analyzed. Including 26 males and 18 females, aged 70 to 86 years old with an average of(77.5±3.5) years, course of disease was 3 weeks to 6 months. Percutaneous transforaminal endoscopic discectomy via lateral position assisted with local anesthesia was performed in the patients. Postoperative straight leg-raising degree change and Nakai criteria were used to evaluate the operative effect. Visual analogue scale(VAS) and JOA scoring system were used to compare the symptom improvement between preoperative and postoperative. RESULTS: No serious complications occurred during and after the operation, and the coexisting medical diseases were not aggravated. All patients safely survived the perioperative period. All the 44 cases were followed up from 6 to 30 months with an average of 20 months. Postoperative straight leg raising angle was obviously improved. At final follow-up, according to Nakai standard, 41 cases got excellent results, 3 good. VAS scores were significantly decreased and JOA scores were significantly increased in final follow-up(P<0.01). CONCLUSIONS: Percutaneous transforaminal endoscopic discectomy via lateral position assisted with local anesthesia is a safe, effective, less invasive technique for the treatment of lumbar disc herniation in elder with systemic diseases. Multidisciplinary collaboration and perioperative well controlled disease are essential for early rehabilitation of such patients.

[Analysis of postoperative survival rates of mucoepidermoid carcinoma in salivary gland].

OBJECTIVE: The pathologic slides and clinical data of 119 patients with mucoepidermoid carcinoma (MEC) of salivary glands were reviewed. All patients underwent surgical therapy in Department of Oral and Maxillofacial Surgery, College of Stomatology, Fourth Military Medical University. The postoperative overall observed survival rates and specific survival rates were statistically caculated, and the correlative clinicopathologic factors influencing the prognosis were evaluated. METHODS: Statistical analysis was performed using the SPSS 10.0 software. The survival rates were obtained by the Kaplan-Meier method. The clinicopathologic parameters were evaluated using log rank test (univariate analysis) and Cox proportional hazards regression model (multivariate analysis). RESULTS: The overall observed survival rates of this group were 92.53%, 87.52% and 85.39% at 5, 10 and 15 years respectively after surgical therapy. Univariate analysis demonstrated that the factors correlated with lower in survival rates were patient's age (> or = 40 years), advanced clinical stage (TNM III, IV stage) and the poorly differentiated tumors (P < 0.05). The survival rates of male patients with MEC in the major salivary glands were significantly lower than those of female patients (P = 0.008). The degree of differentiation, TNM stage and preoperative symptoms were three important prognostic factors that were selected into the Cox proportional hazards regression model. CONCLUSIONS: Most patients with highly differentiated MEC in salivary glands had a favorable outcome after receiving adequate surgical treatment. The degree of differentiation and the TNM stage of MEC in the salivary glands are two useful factors to evaluate the prognosis of these neoplasms.

[A case-control study on the vitamin D receptor gene polymorphisms and susceptibility to pulmonary tuberculosis].

OBJECTIVE: To investigate the association between the genetic polymorphisms of VDR gene and susceptibility to pulmonary tuberculosis. METHODS: Case-control study was conducted. PCR-RFLP technique was used to detect the C/T polymorphism in VDR gene. Information on related factors of tuberculosis was collected using a pre-tested questionnaire. Univariate and multivariate logistic analyses were conducted with SPSS software package. RESULTS: A sample of 76 cases and 171 controls was studied. The genotype frequencies of VDR-FF, VDR-Ff and VDR-ff were 38.2%, 44.7%, 17.1% and 52.6%, 40.9%, 6.4% respectively. VDR-ff was significantly overrepresented in case group, the OR (95% CI) was 3.668 (1.483 - 9.071) when comparing with FF genotype. The significant association remained after adjusting BCG immunization and smoking, the OR (95% CI) was 3.036 (1.117 - 8.253). CONCLUSION: The VDR-ff genotype might be associated with the susceptibility to pulmonary tuberculosis in Chinese Han population.

[A case-control study on natural-resistance-associated macrophage protein 1 gene polymorphisms and susceptibility to pulmonary tuberculosis].

OBJECTIVE: To investigate association between the natural-resistance-associated macrophage protein 1 (NRAMP1) gene polymorphisms and susceptibility to pulmonary tuberculosis (TB) in Chinese Han population. METHODS: Hospital-based case-control study design was adopted. Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) technique were used to type three NRAMP1 polymorphisms (INT4, D543N and 3'UTR). Information on related factors of tuberculosis was collected using a pre-tested standard questionnaire. Univariate and multivariate unconditional logistic analyses were conducted using SPSS for window software package. Totally, 110 cases of TB were selected during April 2001 to June 2002, with an average age of (27.7 +/- 12.7) years. Also, 180 cases of healthy control were selected, aged (27.3 +/- 9.2) years in average. Locus of NRAMP1 polymorphism was analysed with univariate method. RESULTS: Univariate analysis demonstrated that the D543N G/A and 3'UTR TGTG+/del genotype occurred more frequently in the cases than in the controls, with crude odds ratios (OR) (95% CI) of 2.22 (1.03 - 4.78) and 1.93 (1.14 - 3.26), respectively. No significant association was observed between TB and INT4 polymorphisms. In multivariate analysis, associations of TB and D543N G/A and 3'UTR TGTG+/del genotypes remained, adjusted for exposure history and bacille Camette-Guérin immunization. Adjusted OR (95% CI) was 3.04 (1.12 - 8.27) and 2.36 (1.20 - 4.64), respectively. Still, no significant association between INT4 polymorphisms and TB was found. CONCLUSION: Polymorphisms of D543N and 3'UTR locus in NRAMP1 gene might affect their susceptibility to TB in Chinese Han population.