The Danish Twin Apartment Study – Part II: Mathematical modeling of the relative strength of sources of indoor air pollution

Abstract This study deals with the modeling of air pollution in apartments from laboratory measurements of source strengths, using formaldehyde and Total Volatile Organic Compounds (TVOCs) as model pollutants. The sources in two test apartments were grouped into two: building-related sources and occupant-related sources. The measured source strengths and ventilation rates were used for the prediction of concentrations expected in the apartments. These predictions were compared to measurements in the apartment over 12 months. The conclusions were that the model predictions based on emission rates measured in the laboratory can be used to predict the long-term concentration of the two model pollutants in the apartments. Considering the measured differences in ventilation between the apartments, an occupant emission rate of between 0.2 and 0.3 mg/h/kg body weight could be estimated. Based on previous suggested limits of acceptable exposures of humans to VOCs, an acceptable average emission rate of VOCs from building materials in general was estimated to be about 30 (μ/m²/h. The modeling showed that during the first 200 days, building materials dominated the emissions. After this, sources relating to the occupants dominated. On average about half of the VOC pollution originated from the building materials.     

Terephthalic acid decomposition by photocatalytic ozonation with VxOy/ZnO under different UV-A LEDs distributions

Abstract

In this work, the degradation of terephthalic acid (TA) by vanadium oxide (V_xO_y) supported on zinc oxide (ZnO) was evaluated in a photocatalytic ozonation treatment based on two UV-A LEDs distributions. TEM analysis and specific surface area measurement suggest that V_xO_y is not supported on ZnO, while the EDXRF and XPS analysis indicated the presence of V_xO_y. The XPS analysis on V_xO_y/ZnO catalyst showed non-significant surface change between fresh and used catalyst. However, ozone decomposition showed a higher reaction rate constant for catalytic (230%) and photocatalytic ozonation (310%) in comparison with single ozone treatment. Photocatalytic ozonation with central and external irradiation arrays was evaluated in TA elimination by a kinetic study. The irradiation arrays had not statistical differences in the TA decomposition or oxalic acid formation. These results suggest that the construction of central bodies inside the reactor could be not necessary for photocatalytic processes.     

无铅阴极的相变致电子发射研究

研究了最新无铅阴极钛酸铋钠(Na1 2Bi1.2TiO3，NBT)基铁电陶瓷的电子发射性能和电子发射的机理。采用常规陶瓷工艺制备了发射阴极样品，并在阴极上施加高达15kV的激励脉冲，获得了20A／cm^2的最大发射电流密度。在施加激励电压的同时观察到3个发射电流脉冲峰值，该现象不同于其他的阴极。通过测试NBT基铁电陶瓷的相变性能，修正了得到公认的快极化反转致电子发射理论，提出相变致电子发射理论公式，合理解释了该新型无铅NBT基阴极的电子发射3个峰现象，说明了电子发射不仅可以由快极化反转产生，也可以由相变导致的极化变化产生。     

我国天然气工业的发展及面临的挑战

天然气净化工艺中硫回收装置的行业特性与GB 16297-1996标准中规定的SO2排放标准严重脱节,硫回收装置将形成天然气工业发展的"瓶颈".基于国情,本文认为应制定有关天然气行业SO2排放标准,其中包括视装置处理规模分段规定最低硫回收率;不回收硫的潜硫量上限,以促进天然气工业进一步的发展.     

Sensory evaluation and chemical analysis of exhaled and dermally emitted bioeffluents

Conditions in which exhaled and dermally emitted bioeffluents could be sampled separately or together (whole‐body emission) were created. Five lightly dressed males exhaled the air through a mask to another, identical chamber or without a mask to the chamber in which they were sitting; the outdoor air supply rate was the same in both chambers. The carbon dioxide concentration in the chamber with exhaled air was 2000 ppm. Chamber temperatures were 23°C or 28°C, and ozone was present or absent in the supply airflow. When dermally emitted bioeffluents were present, the perceived air quality (PAQ) was less acceptable, and the odor intensity was higher than when only exhaled bioeffluents were present. The presence or absence of exhaled bioeffluents in the unoccupied chamber made no significant difference to sensory assessments. At 28°C and with ozone present, the odor intensity increased and the PAQ was less acceptable in the chambers with whole‐body bioeffluents. The concentrations of nonanal, decanal, geranylacetone, and 6‐MHO were higher when dermally emitted bioeffluents were present; they increased further when ozone was present. The concentration of squalene then decreased and increased again at 28°C. Dermally emitted bioeffluents seem to play a major role in the sensory nuisance experienced when occupied volumes are inadequately ventilated.     

Kinetics of emitted mass—A study with three dry powder inhaler devices

The purpose of this study was to understand the kinetics of emptying of micronised salbutamol sulphate (SS) and lactohale 300 (LH300) under varying air flow rates (30–180 L min⁻¹) from three dry powder inhaler devices, Rotahaler^® (RH), Monodose Inhaler^® (MI) and Handihaler^® (HH). Aerosol concentration vs. time profiles, determined through real-time laser diffraction particle sizing, demonstrated that the majority of the powder from RH was emitted within one second while a more prolonged aerosolisation was observed from MI and HH. Peak aerosol concentrations were achieved more rapidly from RH compared to MI for both SS and LH300. Calculated cumulative emitted mass (CCEM) vs. time profiles were obtained from the aerosol concentration vs. time profiles and the emitted mass and the rate of CCEM (k_CCEM), estimated from a modelling approach, increased with increasing air flow rates. The k_CCEMvs. air flow rate profiles of SS and LH300 were significantly different at high air flow rates. The k_CCEM was highest from RH and lowest from MI. Differences in k_CCEM between the devices were related to capsule aperture size while the differences between the materials were due to the powder bed structure. This approach provided an understanding of the rate at which powder mass emptied from dry powder inhaler devices and was proposed to be a powerful development tool for the future powder inhalers.     

冷发射电子束掺杂磷

一种新的冷发射电子束掺杂方法已研究成功。这种方法可实现高浓度(C_(max)=2.8×10~(20)/cm~3),超浅结[(x_j)_(min)≤0.1μm],而且损伤比离子注入的小得多。用这种方法制备的太阳能电池控制器件性能很好。     

环保型酚醛树脂粘合剂的研制及粘接性能

对酚醛树脂粘合剂的合成进行了研究 ,采用将甲醛和苯酚在不同反应阶段分批加入的工艺流程 ,使得粘合剂产品在符合粘接性能要求的基础上 ,有效地降低了产品的游离甲醛和制板后甲醛释放量。用该粘合剂粘接的胶合板甲醛释放量不超过 0 .0 5mg·L-1,远远低于国家标准。该粘合剂也适用于竹板的粘接 ,它是一种比较理想的低毒环保型酚醛树脂粘合剂     

The effects of warmth and CO2 concentration,with and without bioeffluents,on the emission of CO2 by occupants and physiological responses

The emission rate of carbon dioxide (CO₂) depends on many factors but mainly on the activity level (metabolic rate) of occupants. In this study, we examined two other factors that may influence the CO₂ emission rate, namely the background CO₂ concentration and the indoor temperature. Six male volunteers sat one by one in a 1.7 m³ chamber for 2.5 h and performed light office-type work under five different conditions with two temperature levels (23 vs. 28°C) and three background concentrations of CO₂ (800 vs. 1400 vs. 3000 ppm). Background CO₂ levels were increased either by dosing CO₂ from a cylinder or by reducing the outdoor air supply rate. Physiological responses to warmth, added CO₂, and bioeffluents were monitored. The rate of CO₂ emission was estimated using a mass-balance equation. The results indicate a higher CO₂ emission rate at the higher temperature, at which the subjects were warm, and a lower emission rate in all conditions in which the background CO₂ concentration increased. Physiological measurements partially explained the present results but more measurements are needed.     

室外人体受地面热辐射的理论计算模型

室外地面热辐射包括地表面本身发射辐射和反射辐射,是影响人体室外热感觉的重要因素。本文首先通过合理的基本假设,认为地面辐射符合兰贝特余弦定律,将室外人体等效为一柱体——"人体柱",然后建立"人体柱"受地面热辐射的物理数学模型,通过对物理数学模型进行理论分析,获得了室外人体受地面热辐射量的理论计算关系式。该关系式表明:在地面性质一定的条件下,人体受地面热辐射随离人体距离的增加而迅速减少,离人体距离8 m范围内的辐射占人体受到地面总辐射的90%左右。所得结论对于确定室外人体受地面热辐射量具有重要的理论意义,对于室外地表绿化和水体设置具有参考价值和指导作用。