自动快速燃烧炉-离子色谱联用技术检测水泥等建材中的氯

建立了一种全新的以燃烧方法处理固体样品的装置——自动快速燃烧炉(AQF)与离子色谱联用的技术,检测建筑材料中氯的方法.该方法将AQF的快速处理样品的能力和离子色谱的准确性好、灵敏度高的特点相结合,可以连续批量处理样品,平均在18 min之内完成一个样品的检测.方法的线性、重现性、检测限均令人满意.还进行了水提法处理待测样品,将其结果与AQF处理的结果相比较,结果表明AQF处理的方法具可行性.     

重庆市江津区空气污染指数变化特征及影响因素分析

以2010~2014年重庆市江津区两个环境空气自动监测站逐日空气污染指数(API)、主要污染因子和空气质量级别为基础,分析了近5年该区空气质量变化特征.结果表明,重庆市江津区城市空气质量总体上以优、良天数为主,主要污染因子为可吸入颗粒物.API从时间变化上看,冬季空气质量最差,春秋季次之,夏季最好.气象因子、地理条件以及人类活动对城区空气质量影响显著.     

Hydrogen bond effect of azido polyurethane elastomer by dynamic mechanical analysis

Hydrogen bond effects in azido polyurethane elastomers (APUE) have been studied by dynamic mechanical analysis (DMA) and the results show that the hydrogen bond effect has stronger temperature dependence. The activation energy of hydrogen bond dissociation (E_a) and the hydrogen bond density (vs/V) have been evaluated from the elastic modulus–temperature relationship. The calculated E_a in this work is much higher than the reported values of normal polyurethane elastomer (PUE). The values of E_a are 81.3, 68.1, 53.3, and 42.3 kJ/mol at 150, 110, 50, and 20 Hz, respectively, for PUE‐1 (CPPB/HDI trimer elastomer); 94.6, 75.8, 48.4, and 36.9 kJ/mol at 150, 110, 50, and 20 Hz, respectively, for PUE‐2 (APPB/HDI trimer elastomer); 82.1, 74.4, 59.8, and 46.5 kJ/mol at 150, 110, 50, and 20 Hz, respectively, for PUE‐3 (APPB/HDI trimer/EG elastomer); 145, 124, 88.0, and 75.5 kJ/mol at 150, 110, 50, and 20 Hz, respectively, for PUE‐4 (APPB/HDI trimer/BD elastomer); and 72.2, 64.3, 49.8, and 39.9 KJ/mol at 150, 110, 50, and 20 Hz, respectively, for PUE‐5 (APPB/HDI trimer/HD elastomer). The DMA estimations are semiquantitative for it ignores other physical crosslinking effects and the results give relative order of vs/V and E_a. The values of vs/V of crosslinked APUE (PUE‐3, PUE‐4, and PUE‐5) are much higher than PUE‐2. The test frequency could affect the values of vs/V and higher frequency would minify the difference of the values of vs/V for two given temperatures. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2841–2851, 2006     

Oxygen concentration-related impedance spectroscopic studies of La2Mo2O9 oxide ion conductors

Ionics - The frequency dispersion of impedance, relaxation, and modulus formalism under oxygen, air, and nitrogen atmospheres are performed on La2Mo2−x W x O9 (x = 0, 0.3, 0.5,...     

Hopf bifurcation control for stochastic dynamical system with nonlinear random feedback method

Hopf bifurcation control in nonlinear stochastic dynamical system with nonlinear random feedback method is studied in this paper. Firstly, orthogonal polynomial approximation is applied to reduce the controlled stochastic nonlinear dynamical system with nonlinear random controller to the deterministic equivalent system, solvable by suitable numerical methods. Then, Hopf bifurcation control with nonlinear random feedback controller is discussed in detail. Numerical simulations show that the method provided in this paper is not only available to control the stochastic Hopf bifurcation in nonlinear stochastic dynamical system, but is also superior to the deterministic nonlinear feedback controller.     

荧光玻璃封装芯片级白光LED光热性能

芯片级封装是实现高光密度白光LED和减小封装体积的一种重要途径,而目前芯片级白光LED存在荧光层老化、荧光粉热猝灭等问题,严重影响白光LED的性能和可靠性。为此,本文结合荧光玻璃的技术优势,提出了荧光玻璃封装芯片级白光LED,并分析了白光LED光热性能。利用丝网印刷和低温烧结工艺在玻璃基片表面制备了荧光玻璃层,从而获得了晶圆级荧光玻璃片,再切割成芯片级荧光玻璃用于白光LED封装。分析了荧光玻璃层的微观形貌,荧光粉颗粒内嵌在玻璃基体中,膜层致密、无明显残余气孔;通过调节荧光玻璃层厚度优化了白光LED光学性能,当荧光玻璃层为120μm时,白光LED获得了最优光学性能,光效、色温和色坐标分别为111.8lm/W、6876K和(0.3074,0.3214);分析了荧光玻璃封装结构对白光LED光热性能的影响,荧光玻璃层靠近LED芯片封装具有更高的光效和更低的色温,同时白光LED表面温度更低。     

含空腔的功能梯度声学覆盖层水下吸声特性

针对传统的声学覆盖层吸声频带窄的问题,基于功能梯度材料的特点提出了一种含空腔结构的水下功能梯度声学覆盖层结构,引入梯度有限元法建立了功能梯度型声学覆盖层的水下声学计算模型,研究了功能梯度声学覆盖层结构的水下吸声特性。与传统的功能梯度结构声学建模方法相比,在保证计算精度和计算效率的基础上,文中所建立的功能梯度结构声学计算模型可适用于更复杂的功能梯度声学结构声学性能评估。研究结果表明,功能梯度声学覆盖层能够有效改善中高频段的吸声性能,获得较好的宽频吸声效果。此外,空腔形状采用锥型空腔结构或者组合型空腔结构可以有效地拓宽功能梯度声学覆盖层的吸声频带。     

α- 萘氧乙酸无保护流体室温磷光的重原子效应及有机溶剂的影响

萘氧乙酸（ＮＯＡ）是一类植物生长调节剂．对ＮＯＡ在β－环糊精（β－ＣＤ）保护下的室温磷光（ＲＴＰ）性质［１］和荧光性质［２］研究已有报道,但无保护性介质存在下的ＲＴＰ性质研究尚未见报道．我们在研究丹磺酰氯及其衍生物的无保护流体室温磷光（ＮＰ－ＲＴＰ）...