Resuspension of coal and coal/municipal sewage sludge combustion generated fine particles for inhalation health effects studies

Airborne particulate matter (PM) is an important environmental issue because of its association with acute respiratory distress in humans, although the specific particle characteristics that cause lung damage have yet to be identified. Particle size, acid aerosols, water-soluble transition metals (e.g. Cu, Fe, V, Ni and Zn), polyaromatic hydrocarbons, and particle composition are the focus of several popular hypotheses addressing respiratory distress. All of the above mentioned characteristics are contained in PM generated from the combustion of both pulverized coal, and biomass, including dried municipal sewage sludge (MSS). In this investigation, we report results from collaborative interdisciplinary research on the inhalation health risks caused by particles emitted from the co-combustion of municipal sewage sludge (MSS) and coal. A solid particle resuspension system was implemented to resuspend ash particles. Mice were exposed to resuspended coal and MSS/coal ash particles. Mice exposed to MSS/coal ash particulate demonstrated significant increases in lung permeability, a marker of the early stages of pathological lung injury, while the mice exposed to coal-only ash did not. These results show that the composition of particles actually inhaled is important in determining lung damage. Zinc was significantly more concentrated in the MSS/coal ash than coal ash particles and the pH of these particles did not differ significantly. Specifically, an MSS/coal mixture, when burned, emits particles that may cause significantly more lung damage than coal alone, and that consequently, the use of MSS as a 'green', CO2-neutral replacement fuel should be carefully considered.     

Size and mineral composition of airborne particles generated by an ultrasonic humidifier

This study describes the size distribution and concentration of particles expelled by a portable, 3‐L ultrasonic humidifier. The ultrasonic humidifier was filled with waters of varying mineral content and hardness. Aerosol size distributions were measured during 8 hours of humidifier operation in a typical bedroom. Humidifiers produced approximately 1.22 × 10¹⁰‐2.50 × 10¹⁰ airborne particles per milliliter of water consumed, resulting in airborne particle concentrations of 3.01‐5.91 × 10⁴ #/cm³, with modes ranging between 109 and 322 nm in diameter. The emission rate of particles varied by water type from 1.02 × 10⁹ to 2.27 × 10⁹ #/s. Lower mineral waters produced fewer, smaller particles when compared to higher mineral waters. Chemical analyses of particles collected with a cascade impactor indicated that the minerals in emitted particles had the same relative mineral concentrations as the fill water. Our results demonstrate that ultrasonic humidifiers should be considered a source of inhalation exposure to minerals dissolved in water, and that the magnitude of exposure to inhalable particles will vary with water quality.     

高分子材料的燃烧生成气体及其毒性

论述了高分子材料燃烧时所产生的烟气组成及主要燃烧生成气体的毒性，指出高分子类材料主要燃烧生成物是二氧化碳和一氧化碳，实验结果可以得出：燃烧奈件不同，即使燃烧生成物是相同的物质，其所产生的种类和量也各不相同。     

Physical and chemical characterization of tire-related particles: Comparison of particles generated using different methodologies

The purpose of this study was to characterize the physical and chemical properties of particles generated from the interaction of tires and road surfaces. Morphology, size distribution, and chemical composition were compared between particles generated using different methods, including on-road collection, laboratory generation under simulated driving conditions, and cryogenic breaking of tread rubber. Both on-road collected and laboratory generated particles exhibited the elongated shape typical of tire wear particles, whereas tread particles were more angular. Despite similar morphology for the on-road collected and the laboratory generated particles, the former were smaller on average. It is not clear at this stage if the difference is significant to the physical and chemical behavior of the particles. The chemical composition of the particles differed, with on-road generated particles containing chemical contributions from sources other than tires, such as pavement or particulates generated from other traffic-related sources. Understanding the differences between these particles is essential in apportioning contaminant contributions to the environment between tires, roadways, and other sources, and evaluating the representativeness of toxicity studies using different types of particulate generated.     

Numerical study of the transport of droplets or particles generated by respiratory system indoors

The outbreak of atypical pneumonia, referred to as severe acute respiratory syndrome (SARS), has spread to many countries in the world. SARS may infect human bodies by the tiny droplets or particles carrying various virus and bacteria, which are generated by the respiratory system of infected patients. This paper presents the numerical analysis of the influence of generating ways of the droplets or particles on the transport and distribution of the droplets or particles indoors. The drift flux model, which considers the settling of particles or droplets under the effect of gravitational sedimentation, is adopted to simulate the droplets transport and distribution indoors during respiration and sneezing or coughing process, while the simplified model for solving the continuous fluid flow is combined. Two different cases considering the normal respiration and coughing or sneezing are studied, respectively, and two different outlet velocities from the mouth for the sneezing or coughing process are considered. The results show that droplets or particles generated by normal breathing process transport a relatively short distance, while droplets or particles generated during coughing or sneezing may travel much longer distances, which may pose adverse effect on human bodies for defending the SARS or other infectious diseases.     

Association of cadmium with MnO2 particles generated during permanganate oxidation

Particle filtration and cadmium sorption studies were performed at selected time points during reaction of potassium permanganate with trichloroethylene under varied reaction matrix conditions. The purpose of the studies was to determine the potential impact of manganese oxides particle generation, a by-product of the permanganate reaction, on subsurface metal mobility, with cadmium serving as a representative metal of interest in the environment. Results of the studies indicate that the association of cadmium with the manganese oxides is a function of (1) particle concentration, (2) pH, (3) the presence of calcium in the reaction matrix, and (4) the rate of particle generation and agglomeration. Based on these findings, it is important to give careful consideration to subsurface conditions that can potentially impact the mobility of metals present naturally or as co-contaminants. If subsurface conditions are not appropriately characterized and planned for, deleterious effects could result, including long-term release of metals initially sorbed onto generated particles. Alternatively, the generated manganese oxides may serve as a long-term means of immobilizing metals within the subsurface.     

Characteristics of electromagnetic vector field generated from rock fracturing

Rock fracturing is often accompanied by electromagnetic phenomenon. As a vector field, in addition to the intensity that is widely concerned, the generated electromagnetic field also has obvious directionality. To this end, a set of electromagnetic antennas capable of simultaneous three-axis measurement is used to monitor the electromagnetic vector field generated from rock fracturing based on Brazilian tests. The signal amplitude on each axis can represent the magnitude of actual magnetic flux density component on the three axes. The intensity and directional characteristics of electromagnetic signals received at different positions are studied using vector synthesis. The directionality of electromagnetic radiation measured using a three-axis electromagnetic antenna shows that the direction of the magnetic flux intensity generated by rock fracturing tends to be parallel to the crack surface, and the measured signal intensity is greater in a direction closer to the crack surface.     

On the flight paths of metal particles and embers generated by power lines in high winds-a potential source of wildland fires

In dry grasslands, dangerous wildfires are of particular concern during hot, dry seasons in regions encountering high winds. It is possible that such winds can cause power cables to come close enough together to arc or collide with trees, and produce metal sparks or burning embers which can be carried by the wind and land in adjacent areas of dry vegetation. A major issue is whether or not such possibly generated particles can initiate a brush or grass fire. In this work, a predictive, numerical model is used to calculate trajectories, combustion rates, and lifetimes of metal particles and burning embers of different sizes for various wind conditions and terrain. Three distinct cases are studied: (1) hot particles produced by arcing copper power lines; (2) burning sparks produced by arcing aluminum power lines; and (3) burning embers produced by the collision of high voltage power lines with surrounding trees. The results show that for the same wind conditions, the distances reached by firebrands are the greatest, followed by aluminum and copper. Large aluminum sparks (e.g. 1·5 mm diameter) that do not burn up in flight travel farther than copper particles of the same size. Since copper particles do not emerge burning, they immediately cool down in flight, as they are carried away by the wind. Nonetheless, with a slightly larger heat capacity than that of aluminum (and non-regressing size), a copper particle can bring with it a significant amount of heat into its area of impact. Although smaller aluminum particles can burn out while in flight, larger aluminum particles can land while still burning. Burning embers or firebrands burn heterogeneously and are not susceptible to high Re extinction due to flame blow-off. Larger embers can land still burning; however, they may carry less heat than their metal counterparts.     

Ultrafine particles generated from coloring with scented markers in the presence of ozone

High concentrations of ultrafine particles (UFPs) have been previously reported during school art activities. This is possibly due to secondary organic aerosols (SOAs) formed from reactions between ozone and volatile organic compounds emitted from art products. Four brands of markers, three scented and one unscented, were tested inside a stainless steel chamber at eight different ozone concentrations between 0 and 300 ppb. Out of the 32 tested markers, only the lemon‐ and orange‐scented markers from one brand reacted with ozone to form UFPs. Limonene, pinene, and several other terpenes were identified as ingredients of ink in SOA‐forming markers. Coloring with one lemon‐scented marker for 1 min without ozone generated on average approximately 26 ± 4 ppb of limonene inside the chamber. At 150 ppb ozone, using one lemon marker for 1 min formed on average 7.7 × 10¹⁰ particles. The particle size distribution indicated an initial mode of 15 nm which grew to 40 nm. At 50 ppb ozone and below, no significant SOA formation occurred. The number of particles formed is moderately correlated with the mass of ink used (R² = 0.68). Based on these data, scented markers are not likely a strong source of SOA under normal indoor ozone levels.     

Application of electrostatic precipitator in collection of smoke particles from hospital wastes combustion

The paper reports the development and implementation of a cost-effective electrostatic precipitator (ESP) prototype for the medical wastes incinerator of university hospital centre (CHU) of Sidi-Bel-Abbes, using a water washing system for cleaning electrodes. The impact of medical waste incineration on human health is a topical debate. The incineration process is a safe mode of disposal [OK] of such waste, but it is not an effective solution and needs a pollution control system. Generally, in Africa, cost is the major constraint for manufacturers and users. A half-scale ESP model was initially used for an experimental study in the laboratory. Thereafter, a full-scale model was produced and installed for the incinerator based on the optimal values obtained from this preliminary study.     

Analytical electron microscopy of combustion particles: a comparison of vehicle exhaust and residential wood smoke

Particulate matter has been associated with a number of adverse health effects. Since combustion particles from vehicle exhaust and wood smoke are common constituents of ambient air, the morphology and elemental composition of particles from these two sources were analysed and compared using single particle analysis. Ambient air particles were collected in locations dominated by vehicle exhaust or residential wood smoke. To verify the source contributions to the ambient air samples, particles were collected directly from the combustion sources. All particulate samples were analysed on carbon extraction replica by transmission electron microscopy (TEM) and X-ray microanalysis (XRMA). The particles were classified into four groups based on morphology and elemental composition. Carbon aggregates were the only particles identified to originate from combustion sources and accounted for more than 88% of the particle numbers in the ambient air samples from both sources. The carbon aggregates were therefore further analysed with respect to morphology and elemental composition on germanium extraction replica. Carbon aggregates from vehicle exhaust were characterised by higher levels of Si and Ca compared to wood smoke aggregates that contained higher levels of K. The S content in aggregates from both sources was probably caused by interaction with gases in the air. Furthermore, the diameters of primary particles from vehicle exhaust were significantly smaller (27+/-7 nm) than the diameters for wood smoke (38+/-11 nm). The observed differences in elemental profiles and primary particle diameters for vehicle exhaust and wood smoke may influence the health effects caused by these particles.     

碎石颗粒的压缩变形与破碎特性

基于颗粒流软件PFC2D,建立了颗粒接触本构模型,考虑不同孔隙率的大颗粒对压缩结果的影响,分别模拟了孔隙率为0.1,0.16,0.2,0.25四种颗粒在单轴压缩下的破碎与变形过程,为探究碎石颗粒的压缩变形和破碎特性提供了新的方法。     

Characteristics of cement mortar with nano-SiO2 particles

The properties of cement mortars with nano-SiO₂ were experimentally studied. The amorphous or glassy silica, which is the major component of a pozzolan, reacts with calcium hydroxide formed from calcium silicate hydration. The rate of the pozzolanic reaction is proportional to the amount of surface area available for reaction. Therefore, it is plausible to add nano-SiO₂ particles in order to make high-performance concrete. The experimental results show that the compressive strengths of mortars with nano-SiO₂ particles were all higher than those of mortars containing silica fume at 7 and 28 days. It is demonstrated that the nano-particles are more valuable in enhancing strength than silica fume. In addition, the continuous hydration progress was monitored by scanning electron micrograph (SEM) observation, by examining the residual quantity of Ca(OH)₂ and the rate of heat evolution. The results of these examinations indicate that nano-scale SiO₂ behaves not only as a filler to improve microstructure, but also as an activator to promote pozzolanic reaction.     

无机固形物对重金属的吸附去除特性研究

采用石英砂和高岭土为吸附剂,以典型重金属Cu,Zn,As,Cr为吸附质分别进行了单吸附剂单吸附质等温吸附实验,研究了无机颗粒物对重金属离子的吸附去除特性以及无机颗粒物对金属离子吸附水相化学条件影响因素,得出了一些有参考价值的结论。     

Quantifying the contribution of ambient and indoor‐generated fine particles to indoor air in residential environments

Indoor fine particles (FPs) are a combination of ambient particles that have infiltrated indoors, and particles that have been generated indoors from activities such as cooking. The objective of this paper was to estimate the infiltration factor (F_inf) and the ambient/non‐ambient components of indoor FPs. To do this, continuous measurements were collected indoors and outdoors for seven consecutive days in 50 non‐smoking homes in Halifax, Nova Scotia in both summer and winter using DustTrak (TSI Inc) photometers. Additionally, indoor and outdoor gravimetric measurements were made for each 24‐h period in each home, using Harvard impactors (HI). A computerized algorithm was developed to remove (censor) peaks due to indoor sources. The censored indoor/outdoor ratio was then used to estimate daily F_infs and to determine the ambient and non‐ambient components of total indoor concentrations. F_inf estimates in Halifax (daily summer median = 0.80; daily winter median = 0.55) were higher than have been reported in other parts of Canada. In both winter and summer, the majority of FP was of ambient origin (daily winter median = 59%; daily summer median = 84%). Predictors of the non‐ambient component included various cooking variables, combustion sources, relative humidity, and factors influencing ventilation. This work highlights the fact that regional factors can influence the contribution of ambient particles to indoor residential concentrations.     

Noise generated by intermittent structure borne vibrations

Professor Grootenhuis discusses noise levels due to structural vibration and describes how they can be predicted with some confidence under steady state conditions. His case studies relate to flats in a building in the Barbican in London over railway tracks, and also measurements taken in the Royal Festival Hall.     

隧道施工引起地层移动及变形分析

简述了城市隧道施工的有关要求,探讨了地表变形与沉降对建筑物的影响,采用数值模拟和理论分析相结合对地表沉降进行了定性和定量分析,以确保地下工程建设质量。     

萘系高效减水剂废渣的开发利用

采用简单可行的工艺方法将萘系减水剂废渣进行无害化处理和利用,将废渣打碎后加水溶解成悬浮液,用离心法或沉淀法将废渣悬浮液中的萘系减水剂分离出来,硫酸钙等固相物经过风干或晒干后用作建筑材料,为充分利用萘系高效减水剂废渣开辟了新途径。     

Making the invisible segregation of diverse neighbourhoods visible

Journal of Housing and the Built Environment - There are not clear understandings of the mechanisms of diverse populations in Tehran although it is considered as one of the most diverse...     

Detection and monitoring by FSM for fatigue crack at invisible location of steel plate deck with U-rib

For verifying the applicability of FSM, which is one of the non-destructive inspections based on the potential difference method, for fatigue cracks generated at the invisible location of a steel plate deck with U-rib, a series of experiment and numerical analysis was carried out. In the fatigue experiment, it was confirmed that cracks initiated at the roots of the welds between the deck plate and the U-rib. They propagated concentrically from the roots into the thickness direction of the deck plate. The FC values obtained by the static electric field analysis were agreed with the experimental results. It was indicated that the initiation and propagation of fatigue crack could be detected and monitored by FSM. It was known that the crack initiation at either welds of the left or right sides of the U-rib could be judged by noting the behavior of the FC value of the pair. It was confirmed that the initiation and propagation of fatigue cracks could be detected and monitored with high accuracy by FSM with noting the FC value of the pair possible to be used actually.