An Aerosol Wind Tunnel for Evaluation of Massive-Flow Air Samplers and Calibration of Snow White Sampler

Massive-flow air samplers are being deployed around the world to collect aerosol samples for analysis of radioactivity as a result of nuclear tests and nuclear accidents. An aerosol wind tunnel capable of an 1100 m³ min^?1 flow rate was built at Lovelace Respiratory Research Institute (LRRI) to test the sampling efficiency of these samplers. This aerosol wind tunnel uses a stationary air blender to enhance mixing, and therefore it achieves the required uniform distribution of wind speed and aerosol concentration in the test section. The test section of the wind tunnel has a cross section that is 4.3 m × 3.7 m. The aerosol wind tunnel was tested for performance in terms of distribution of wind speed, turbulent intensity, SF₆ tracer gas concentration, and aerosol concentration. Test criteria consistent with U.S. Environmental Protection Agency (EPA) and American National Standards Institute (ANSI) standards were adopted as the guidelines for the aerosol wind tunnel. Additional criteria for aerosol wind tunnel were also recommended. Initial test of the aerosol wind tunnel showed that the wind tunnel could be operated in a wind speed range of 2 to 24 km h^?1. Within this range, the distribution of wind speed SF⁶ trace gas concentration and aerosol concentration in two-thirds of the central area of the test section showed coefficient of variances (COVs) of less than 10% for the range of wind speeds. This met the stringent guidelines for aerosol wind tunnel performance set by EPA and ANSI standards.

The LRRI wind tunnel was used to evaluate the collection efficiency of the sampling head of massive-volume air samplers, including the Snow White sampler. The sampler was tested in this aerosol wind tunnel for particles between 2 and 20 μm. The sampling flow rates were 500 and 700 m³ h^?1 for the tested wind speeds of 2.2 and 6.6 m S^?1, respectively. The results showed that sampling efficiency was influenced by both sampling flow rate and wind speed. The sampling efficiency decreased with an increase in particle size of between 2 and 20 μm. The sampling efficiency also decreased as the wind speed was increased from 2.2 to 6.6 m S^?1.     

Deposition of Fiber in the Human Nasal Airway

Inhalation is the main route for aerosol entering the human body. Many occupational lung diseases are associated with exposure to fiber aerosol in the workplace. However, very few studies to date have been conducted for investigating fiber deposition in the human airway. As a result, there is a notable lack of information on the nature of the fiber deposition pattern in the human respiratory tract. With this in mind, this research consisted of a large number of experimental works to investigate the effects of fiber dimension on the deposition pattern for a human nasal airway. Carbon fibers with uniform diameter (3.66 μm) and polydispersed length were adopted as the test material. Deposition studies were conducted by delivering aerosolized carbon fibers into a nasal airway replica (encompassing the nasal airway regions from vestibule to nasopharynx) at constant inspiratory flow rates of 7.5, 15, 30, and 43.5 l/min. Fibers deposited in each nasal airway region were washed out and the length distribution was determined by microscopic measurement. The results showed that impaction is the dominant deposition mechanism. Most of the fibers with high inertia deposited in the anterior region of the nasal airway (vestibule and nasal valve). In contrast, fibers with low inertia were found to pass through the entire nasal airway easily and collected on the filter at the outlet. Comparing the deposition results between fibers and spherical particles, our data showed that the deposition efficiencies of fibers are significantly lower than that of spherical particles, which implies that the inhaled fibers could pass through the entire nasal airway comparatively easier than spherical particles. Thus, relatively more fibers would be able to enter the lower respiratory tract.     

化学实验中合作策略的研究

学生从实验中获得知识、发展培养各方面能力,在这个过程中,小组合作探究是最佳方式。相对个别学习,我们提出了小组合作学习,也就是学生进行分工合作在各自小组中共同完成学习任务,其本身也是一种学习的组织形式。作者就化学实验中如何发挥学生的合作能力进行了研究,旨在提高学生独立自主性的同时培养其团结合作能力,以适应现代教育改革的需要。     

一个评判精细化工制造公司健康度的指标

阐述了精细化工制造业公司成本和利润结构,定义了公司内外的成本和利润,提出单位内部费用(期间成本加非产品成本)的净利润率即利润费用率是一个评判精细化工制造业公司健康度的指标,并据此作出公司健康定位图。根据公司目前状况在健康定位图所处的区域位置,可明确公司管理要努力和驱动的方向。     

聚合型受阻胺光稳定剂UV3853的合成

单聚合型受阻胺光稳定剂UV3853的合成是以油酸甲酯和2,2,6,6-四甲基-4-哌啶醇为原料,在催化剂钛酸四异丙酯的作用下,以正辛烷为溶剂进行酯交换而得。通过正交实验,取得了较佳的反应条件:n(C9H19NO):n(油酸甲酯)=1.15:1,反应时间为10 h,催化剂用量为油酸甲酯质量的6%。在此条件下合成的产品符合质量标准,产品的收率达95.2%。     

HPLC法测定黄连中盐酸小檗碱和盐酸药根碱

目的:建立黄连水提液中同时测定盐酸小檗碱和盐酸药根碱的高效液相色谱法。方法:加热回流法制备黄连药材水提液,反相高效液相色谱外标法同时测定盐酸小檗碱和盐酸药根碱的含量。结果:盐酸小檗碱和盐酸药根碱的的线性范围分别为:7.5~243.0μg/mL和0.78~34.2μg/mL,平均回收率分别为99.3%和100.1%供试。药材中盐酸小檗碱和盐酸药根碱的含量为21.3 mg/g和9.6 mg/g。结论:该方法能用于黄连药材中盐酸小檗碱和盐酸药根碱的含量测定。     

硅晶切割废砂浆的回收技术及国内专利申请状况

随着我国光伏产业的大起大落,对于相关技术的研究以及专利申请数量也潜移默化地发生了改变。切割废砂浆的综合回收利用对减少环境污染、提高资源利用具有重要意义,更重要的是可以缓解我国太阳能多晶硅的紧缺、减少多晶硅的进口量。文章从国内专利申请情况分析了硅晶切割废砂浆回收处理工艺的发展。     

Determination of the dye‐fixing mechanism of poly(dimethyldiallylammonium chloride)s on cotton fabric

The dye‐fixing mechanism on cotton fabric of poly(dimethyldiallylammonium chloride)s (PDMDAACs) was determined in detail by using several chemical and physical techniques, in order to achieve clear new theoretical guidelines for the wide application of these dyefixatives to different dyes. Findings from previous work showed that the dye‐fixing performance of PDMDAACs can vary with their molecular weights. Analysis by GPC further showed that the polydispersity indexes of the PDMDAACs were 1.22–1.92, which were narrow distributions, but their molecular chain lengths were very different, as indicated by their number‐average molecular weights of 0.69 × 10⁴?1.09 × 10⁵ g/mol and weight‐average molecular weights of 1.33 × 10⁴?1.45 × 10⁵ g/mol. These results indicated that the differences in dye‐fixing performance could be mainly caused by the different molecular chain lengths. Analysis by FTIR of the dyes on dyed cotton samples fixed by PDMDAACs showed absorption shifts similar to those of water‐insoluble color lakes formed from the cationic groups of PDMDAACs and an anionic dye. This finding indicates that the expected color lakes could be formed on dyed cotton fabric when fixing, and that they play a role in the development of the fastness of dyes. However, the interaction between the PDMDAACs and cotton fabric during fixing was confirmed to be very weak. J. VINYL ADDIT. TECHNOL., 19:219‐224, 2013. © 2013 Society of Plastics Engineers     

Glass Additive Influence on the Sintering Behaviors,Magnetic and Electric Properties of Bi–Zn Co‐Doped Co2Y Ferrites

The Bi₂O₃–B₂O₃–ZnO–SiO₂ (BB35SZ) glass effects on the sintering behavior and magnetic properties of Bi–Zn co‐doped Co₂Y ferrites were investigated in developing low‐temperature‐fired ferrites. The results indicate that BB35SZ glass can be used as a sintering aid to reduce the densification temperature of Co₂Y ferrites from 1300°C to 900°C. The 2(Ba_0.9Bi_0.1O)·2(Zn_0.4Co_0.4Cu_0.2O)·6(Fe_1.97Zn_0.03O₃) ferrite with 4 wt% BB35SZ glass can be densified below 900°C, exhibiting an initial permeability of 3.4 and quality factor of 55. This process provides a promising candidate for multilayer chip magnetic devices for microwave applications.     

Novel Low‐Firing Microwave Dielectric Ceramic LiCa3MgV3O12 with Low Dielectric Loss

Novel low temperature firing microwave dielectric ceramic LiCa₃MgV₃O₁₂ (LCMV) with garnet structure was fabricated by the conventional solid‐state reaction method. The phase purity, microstructure, and microwave dielectric properties were investigated. The densification temperature for the LCMV ceramic is 900°C. LCMV ceramic possessed ε_r = 10.5, Q_u × f = 74 700 GHz, and τ_f = ?61 ppm/°C. Furthermore, 0.90LiCa₃MgV₃O₁₂–0.10CaTiO₃ ceramic sintered at 925°C for 4 h exhibited good properties of ε_r = 12.4, Q_u × f = 57 600 GHz, and τ_f = 2.7 ppm/°C. The LCMV ceramic could be compatible with Ag electrode, which makes it a promising ceramic for LTCC technology application.