硝酸银显色法测量混凝土中非稳态氯离子迁移系数的误差分析(英文)

为了评估硝酸银显色法测量非稳态氯离子迁移系数（Dnssm）的误差,采用NTBuild 492中的显色法测量了30组含不同矿物掺合料类型、2个水胶比的砂浆试件。试验结果和理论分析表明：如果不控制硝酸银显溶液的喷洒体积,变色边界氯离子浓度（cd）为0.030～1.020mol/L,当变色深度为5mm时,cd将产生40%Dnssm误差,这对评价高性能混凝土是相当不利的;喷洒的硝酸银溶液体积越小,cd的变化越小。基于本文建立的硝酸银喷洒程序[其中硝酸银溶液喷洒体积为（0.30±0.06）L/m2],假如采用cd=0.070mol/L计算Dnssm,当变色深度（Xd）为5mm时,将产生20%Dnssm误差。在cd=0.200mol/L的情况下,即使Xd小于5 mm,Dnssm误差仍然小于5%。因此,cd=0.070 mol/L并不适合用来计算Dnssm。建立的硝酸银喷洒程序及cd=0.200 mol/L用来测量并计算Dnssm是合理的。     

Estimating Ambient Vapor Pressures of Low Volatility Explosives by Rising‐Temperature Thermogravimetry

Vapor pressure is a fundamental physical characteristic of chemicals. Some solids have very low vapor pressures. Nevertheless numerous chemical detection instruments aim to detect vapors. Herein we address issues with explosive detection and use thermogravimetric analysis (TGA) to estimate vapor pressures. Benzoic acid, whose vapor pressure is well characterized, was used to calculate instrumental parameters related to sublimation rate. Once calibrated, the rate of mass loss from TGA measurements was used to obtain vapor pressures of the 12 explosives at elevated temperature: explosive salts – guanidine nitrate (GN); urea nitrate (UN); ammonium nitrate (AN); as well as mono‐molecular explosives – hexanitrostilbene (HNS); cyclotetramethylene‐tetranitramine (HMX), 4,10‐dinitro‐2,6,8,12‐tetraoxa‐4,10‐diaza‐tetracyclododecane (TEX), cyclotrimethylenetrinitramine (RDX), pentaerythritol tetranitrate (PETN), 3‐nitro‐1,2,4‐triazol‐5‐one (NTO), 1,3,3‐trinitroazeditine (TNAZ), triacetone triperoxide (TATP), and diacetone diperoxide (DADP). Ambient temperature vapor pressures were estimated by extrapolation of Clausius‐Clapeyron plots (i.e. ln p vs. 1/T). With this information potential detection limits can be assessed.     

Mitigation of Single‐Point‐of‐Failure: Development of M127A1 White Star Illuminant Compositions Containing an Epoxy Binder System

A replacement for the M127A1 hand‐held signal illuminant was developed to alleviate concerns associated with single‐point‐of‐failure. In addressing single‐point‐of‐failure, Laminac 4116/Lupersol binder system were replaced with Epon 813/Versamid 140 binder system. Powdered sodium nitrate was replaced with prilled sodium nitrate in the disclosed formulations to minimize hygroscopicity concerns associated with this oxidizer. The performance of the prilled sodium nitrate‐based formulations, their burning behaviors, and the sensitivities of the best performing illuminant toward various ignition stimuli are also described in detail.     

回流污泥预浓缩强化新型氧化沟系统生物除磷的研究(英文)

A pilot-scale,pre-anoxic-anaerobic oxidation ditch was used in this study to treat municipal wastewater with limited carbon source.A novel return activated sludge(RAS) pre-concentration tank was adopted for improv-ing the phosphorus removal efficiency and the effects of RAS pre-concentration ratio were studied.Under the opti-mal operational condition,the suspended total phosphorus(STP) and the total phosphorus(TP) removal efficiencies were around 58.9% and 63.9% respectively and the effluent-P was lower than 0.8 mg·L-1.The reason is that with the optimal RAS pre-concentration ratio,nitrate is completely removed with endogenous carbon source and the secondary phosphorus release is strictly restrained in the pre-anoxic tank.Therefore,the anaerobic phosphorus release and the carbon source uptake by phosphorus accumulation organisms(PAOs) in the sludge,which are ex-tremely important to the phosphorus removal process,can be fully satisfied.Furthermore,the oxidation-reduction potential is proved to be suitable for controlling the RAS pre-concentration ratio due to influent fluctuation and varied conditions.The novel modified system is also beneficial for PAO accumulation.     

硝酸铈铵改性纳米TiO2的合成及其光催化活性研究

以四氯化钛为钛源,硝酸铈铵为改性原料,采用非水体系溶胶-凝胶法制备了二氧化钛催化剂。采用XRD、UV-Vis和SEM等测试技术对样品进行了表征。结果显示:硝酸铈铵的添加抑制了TiO2晶粒的生长,可使其对可见光吸收增强并且改变了其形貌及尺寸。以苯酚为模型,考察了样品的催化性能。结果表明,在n(Ce)∶n(Ti)为0.3%的条件下,于550℃下焙烧的TiO2催化剂的催化活性最好。3 h光照后,苯酚降解率为93.1%。     

改性硝酸铵研究进展及其发展方向

从粒状硝酸铵的问世和发展、抗硬化结晶粉末硝酸铵和不破乳松散性结晶硝酸铵的研究、用于膨化炸药的膨化硝酸铵研制、用于无梯炸药的敏化改性硝酸铵的研究、钝化或防爆硝酸铵的开发、液体硝酸铵在炸药中的应用、改性多孔粒状硝酸铵的研究等方面概述了我国改性硝酸铵的研究成果。开发高性能多孔硝酸铵和防爆的农用硝酸铵及其下游产品,是我国改性硝酸铵今后主要的发展方向。     

镀锌板硅烷-硝酸锆复合转化膜的性能与表征

目的获得一种防腐性能优越的转化膜。方法将KH560和KH791两种硅烷复合后水解,添加硝酸锆,得到KH560-KH791-硝酸锆复合钝化液,采用该钝化液对镀锌钢板进行钝化处理,通过盐水浸泡实验、中性盐雾试验和附着力测试,与添加硝酸锆前的转化膜进行性能对比。结果盐水浸泡和中性盐雾腐蚀72 h的实验中,添加硝酸锆后的转化膜性能都明显优于添加前,二者的附着力测试均能达到一级。结论加入的硝酸锆填充了膜层空隙,更加有效地阻挡了腐蚀介质的渗透,使得钝化膜的防腐性能提高。     

Experimental investigation of decomposition and evaporation characteristics of HAN-based monopropellants

Hydroxylammonium nitrate (HAN)-based monopropellants are among the most promising candidates for eco-friendly rocket engine propellants. They are not carcinogenic or mutagenic, and their thermal decomposition reactions are sufficiently exothermic for military and aerospace applications. Here, an experimental analysis was performed to investigate the characteristics of HAN-based mixtures for monopropellant applications. Three kinds of propellants were prepared for this study: a HAN–water solution, a HAN–water solution with methanol added at a stoichiometric ratio, and a third solution where water was added to further dilute the solution. Two different experimental techniques were used under atmospheric pressure of nitrogen gas environment: thermal analysis and droplet evaporation analysis. Thermal and catalytic decomposition were analyzed using thermo gravimetric analysis. Droplet evaporation was analyzed using a cylindrical vessel equipped with a heating system and a droplet feed, and a high-speed charge-coupled device (CCD) camera. These data were post-processed to calculate the temporal variation of the droplet diameters.     

SOLUBILITIES,DENSITIES, AND REFRACTIVE INDICES FOR THE TERNARY SYSTEMS 1,2-PROPYLENE GLYCOL + MNO3 + H2O (M = Na,K, Rb,Cs) AT 25° AND 35°C

The solubilities, densities, and refractive index data for the 1,2-propylene glycol + MNO₃ + H₂O (M = Na, K, Rb, Cs) ternary systems at 25° and 35°C were measured with mass fractions of 1,2-propylene glycol ranging from 0 to 1.0. In all cases, the presence of 1,2-propylene glycol significantly reduces the solubility of the salts in aqueous solution. The experimental data of density, refractive index, and solubility of saturated solutions for these systems were correlated using polynomial equations. Furthermore, the refractive index and density of unsaturated ternary solutions were also determined and correlated with the salt concentrations and proportions of 1,2-propylene glycol in the systems.     

工业废水反硝化技术研究进展

综述了不同电子供体的生物反硝化过程应用于工业含硝酸盐废水治理的可能性。异养反硝化是非常高效的生物脱氮技术,但用于对低C/N废水的处理时,需要外加碳源而增加运行成本,且外加碳源可能引起二次污染。自养反硝化工艺以硫、氢等作为电子供体,可有效降低运行成本,将是工业废水脱硝的主要处理方法。不管异养反硝化还是自养反硝化工艺,都需进一步开发新的反应器和优化运行条件来降低运行成本。