The great amount of NH3-N produced in biological hydrolysis process of high concentration urea can inhibit the growth of microorganisms. In allusion to this problem,the Fenton reagent was used to treat high concentrat...The great amount of NH3-N produced in biological hydrolysis process of high concentration urea can inhibit the growth of microorganisms. In allusion to this problem,the Fenton reagent was used to treat high concentration urea wastewater. And the optimum conditions of this experiment were employed as follows: Fe(Ⅱ)-H2O2mole ratio was 1/3.53,H2O2 was 4 mL (corresponding to 35.30 mmol),pH was 3.0-3.5. Then the experiment shows that the urea concentration decreases from 500 mg/L to less than 2 mg/L,or is even not detected; under the same dose of H2O2,repetitious addition does better than one-off addition; the reaction time within one minute or to be prolonged has little influence on removal effect. The results verify feasibility of this method.展开更多
The silica fiber reinforced silica and boron nitride-based composites(SiO2f/SiO2-BN) were prepared firstly via the sol-gel method and then the urea route,and the effects of oxidation treatment on the component,structu...The silica fiber reinforced silica and boron nitride-based composites(SiO2f/SiO2-BN) were prepared firstly via the sol-gel method and then the urea route,and the effects of oxidation treatment on the component,structure,mechanical and dielectric properties of the composites were investigated.The results show that the oxidation treatment at 450 °C will not impair the structure of boron nitride,and carbon is the main impurity with the excessive urea.The density of SiO2f/SiO2-BN composites is 1.81 g/cm3,and the flexural strength and elastic modulus are 113.9 MPa and 36.5 GPa,respectively.After oxidation treatment,the density varies to 1.80 g/cm3,and the flexural strength and elastic modulus are decreased to 58.9 MPa and 9.4 GPa,respectively.The mechanical properties of the composites are severely damaged,but they still exhibit a good toughness.The composites show excellent dielectric properties with the dielectric constant and loss tangent being 3.22 and 0.003 9,respectively,which indicates that the oxidation treatment is ineffective to improve the dielectric properties of SiO2f/SiO2-BN composites.展开更多
文摘目的探讨影响急性后循环缺血性卒中(PCIS)患者血管内治疗(EVT)的预后因素。方法回顾性收集2020年1月至2023年8月在中国人民解放军联勤保障部队第九六〇医院行EVT的71例急性PCIS患者的病例资料。术后90 d根据改良Rankin量表(mRS)评分分为预后良好组43例(mRS评分≤2分)和预后不良组28例(mRS评分>2分),比较两组患者的年龄、性别、高血压及糖尿病等一般情况,以及血尿酸(BUA)、血肌酐(Scr)及血尿素氮(BUN)等临床资料。结果共纳入71例发病24 h内入院接受EVT的急性PCIS患者,其中预后良好组43例,预后不良组28例。两组患者在性别、年龄、BUA、总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白胆固醇(LDL-C)、是否有高血压、糖尿病、冠心病、是否吸烟及饮酒等方面比较,差异无统计学意义(P>0.05);单因素分析提示,预后不良组患者的Scr、BUN、术前美国国立卫生研究院卒中量表(NIHSS)评分及14 d NIHSS评分均高于预后良好组,差异有统计学意义(P<0.05)。经多元logistic回归显示,Scr(OR=3.414,P=0.041)、BUN(OR=4.265,P=0.035)是影响急性PCIS患者EVT治疗效果的独立危险因素。所有患者均未发生颅内出血及死亡。结论急性PCIS患者EVT后能部分获益,Scr及BUN升高是影响急性PCIS患者EVT后预后不良的独立危险因素。
文摘The great amount of NH3-N produced in biological hydrolysis process of high concentration urea can inhibit the growth of microorganisms. In allusion to this problem,the Fenton reagent was used to treat high concentration urea wastewater. And the optimum conditions of this experiment were employed as follows: Fe(Ⅱ)-H2O2mole ratio was 1/3.53,H2O2 was 4 mL (corresponding to 35.30 mmol),pH was 3.0-3.5. Then the experiment shows that the urea concentration decreases from 500 mg/L to less than 2 mg/L,or is even not detected; under the same dose of H2O2,repetitious addition does better than one-off addition; the reaction time within one minute or to be prolonged has little influence on removal effect. The results verify feasibility of this method.
基金Projects(50902150,90916019) supported by the National Natural Science Foundation of ChinaProject (9140C8203040905) supported by the State Key Laboratory Foundation of ChinaProject(S100103) supported by the Graduate Innovation Foundation of National University of Defense Technology,China
文摘The silica fiber reinforced silica and boron nitride-based composites(SiO2f/SiO2-BN) were prepared firstly via the sol-gel method and then the urea route,and the effects of oxidation treatment on the component,structure,mechanical and dielectric properties of the composites were investigated.The results show that the oxidation treatment at 450 °C will not impair the structure of boron nitride,and carbon is the main impurity with the excessive urea.The density of SiO2f/SiO2-BN composites is 1.81 g/cm3,and the flexural strength and elastic modulus are 113.9 MPa and 36.5 GPa,respectively.After oxidation treatment,the density varies to 1.80 g/cm3,and the flexural strength and elastic modulus are decreased to 58.9 MPa and 9.4 GPa,respectively.The mechanical properties of the composites are severely damaged,but they still exhibit a good toughness.The composites show excellent dielectric properties with the dielectric constant and loss tangent being 3.22 and 0.003 9,respectively,which indicates that the oxidation treatment is ineffective to improve the dielectric properties of SiO2f/SiO2-BN composites.
