Evolution of Ultrafine Particle Size Distributions Following Indoor Episodic Releases: Relative Importance of Coagulation,Deposition and Ventilation

Indoor ultrafine particles (UFP, <100 nm) undergo aerosol processes such as coagulation and deposition, which alter UFP size distribution and accordingly the level of exposure to UFP of different sizes. This study investigates the decay of indoor UFP originated from five different sources: a gas stove and an electric stove, a candle, a hair dryer, and power tools in a residential test building. An indoor aerosol model was developed to investigate differential effects of coagulation, deposition, and ventilation. The coagulation model includes Brownian, van der Waals, and viscosity forces, and also fractal geometry for particles of >24 nm. The model was parameterized using different values of the Hamaker constant for predicting the coagulation rate. Deposition was determined for two different conditions: central fan on versus central fan off. For the case of a central fan running, deposition rates were measured by using a nonlinear solution to the mass balance equation for the whole building. For the central fan off case, an empirical model was used to estimate deposition rates. Ventilation was measured continuously using an automated tracer gas injection and sampling system. The study results show that coagulation is a significant aerosol process for UFP dynamics and the primary cause for the shift of particle size distribution following an episodic high-concentration UFP release with no fans operating. However, with the central mechanical fan on, UFP deposition loss is substantial and comparable to the coagulation loss. These results suggest that coagulation should be considered during high concentration periods (>20,000 cm^?3), while particle deposition should be treated as a major loss mechanism when air recirculates through ductwork or mechanical systems.

Copyright 2012 American Association for Aerosol Research     

Phenolics,acyl galactopyranosyl glycerol,and lignan amides from <Emphasis Type="Italic">Tetragonia tetragonioides</Emphasis> (Pall.) Kuntze

Eleven antioxidative compounds, including five lignin amides, were isolated from the aerial part of Tetragonia tetragonioides (New Zealand spinach) using 1,1-diphenyl-2-picrylhydrazyl radicalscavenging assay-guided purification. The structures were determined by nuclear magnetic resonance and electrospray ionization-mass spectroscopy. These compounds were identified as methyl linoleate (1), methyl coumarate (2), methyl ferulate (3), 1-O-stearoyl-3-O-β-D-galactopyranosyl-sn-glycerol (4), 1-O-caffeoyl-β-D-glucopyranoside (5), N-trans-caffeoyltyramine (6), cannabisin B (7), cannabisin A (8), Ntrans-feruloyltyramine (9), N-cis-feruloyltyramine (10), and N-trans-sinapoyltyramine (11). Compounds 1, 2, 4, 5, and 8-11 were isolated for the first time from this plant.     

Adiponectin Controls Nutrient Availability in Hypothalamic Astrocytes

Adiponectin, an adipose tissue-derived hormone, plays integral roles in lipid and glucose metabolism in peripheral tissues, such as the skeletal muscle, adipose tissue, and liver. Moreover, it has also been shown to have an impact on metabolic processes in the central nervous system. Astrocytes comprise the most abundant cell type in the central nervous system and actively participate in metabolic processes between blood vessels and neurons. However, the ability of adiponectin to control nutrient metabolism in astrocytes has not yet been fully elucidated. In this study, we investigated the effects of adiponectin on multiple metabolic processes in hypothalamic astrocytes. Adiponectin enhanced glucose uptake, glycolytic processes and fatty acid oxidation in cultured primary hypothalamic astrocytes. In line with these findings, we also found that adiponectin treatment effectively enhanced synthesis and release of monocarboxylates. Overall, these data suggested that adiponectin triggers catabolic processes in astrocytes, thereby enhancing nutrient availability in the hypothalamus.     

Optimal thermo-economic design of a PAFC-ORC combined power system

Journal of Mechanical Science and Technology - Phosphoric acid fuel cells (PAFCs) are appropriate for applications that require high-quality power because of their high reliability. We propose a...     

MIMO receivers considering preamble collisions for grant-free random access in machine type communication systems

Telecommunication Systems - One of the main requirements for next generation mobile or wireless communication systems is to effectively support a large number of machine type communication (MTC)...     

Antioxidant activity and contents of leaf extracts obtained from Dendropanax morbifera LEV are dependent on the collecting season and extraction conditions

Food Science and Biotechnology - This study compared the antioxidant activity of extracts from Dendropanax morbifera (D. morbifera) Levillis leaves. The concentrations of flavonoids and polyphenols...     

A full discretisation of the time-dependent Boussinesq (buoyancy) model with nonlinear viscosity

In this article, we study the time dependent Boussinesq (buoyancy) model with nonlinear viscosity depending on the temperature. We propose and analyze first and second order numerical schemes based on finite element methods. An optimal a priori error estimate is then derived for each numerical scheme. Numerical experiments are presented that confirm the theoretical accuracy of the discretization.     

Ventilation effectiveness as an indicator of occupant exposure to particles from indoor sources

Ventilation effectiveness is an indicator of the quality of supply air distribution in ventilated rooms. It is a representation of how well a considered space is ventilated compared to a perfect air mixing condition. Depending on pollutant properties and source position relative to the airflow, ventilation effectiveness can more or less successfully be used as an indicator of air quality and human exposure. This paper presents an experimentally and numerically based study that examines the relationship between ventilation effectiveness and particle concentration in typical indoor environments. The results show that the relationship varies predominantly with airflow pattern and particle properties. Fine particles (1 μm) follow the airflow pattern more strictly than coarse particles (7 μm), and the high ventilation effectiveness indicates better removal of fine particles than coarse particles. When a ventilation system provides high mixing in the space and ventilation effectiveness is close to one, particle sizes and source location have a relatively small effect on particle concentration in the breathing zone. However, when the supply air is short circuited and large stagnation zones exist within the space, the particle concentration in the breathing zone varies with particle size, source location, and airflow pattern. Generally, the results show that for fine particles (1 μm), increase of ventilation effectiveness reduces occupant exposure; while for coarser particles (7 μm), source location and airflow around the pollutant source are the major variables that affect human exposure.     

Effect of oligomer on dye-sensitized solar cells employing polymer electrolytes

The effect of oligomer (M _n =400–500 g/mol) on dye-sensitized solar cells (DSSC) employing polymer electrolytes consisting of poly(epichlorohydrin-co-ethylene oxide) (Epichlomer), LiI, 1-methyl-3-propylimidazolium iodide (MPII) and I₂ is investigated. Five kinds of oligomer, poly(ethylene glycol) (PEG, M _n =400 and 1,000 g/mol), poly(ethylene glycol) dimethyl ether (PEGDME), poly(propylene glycol) (PPG) and poly(ethylene glycol) diglycidyl ether (PEGDGE), were introduced to elucidate the role of terminal groups and chain length. The coordinative interactions and structures of polymer electrolytes were characterized by FT-IR spectroscopy and X-ray diffraction (XRD). The improved interfacial contact between the electrolytes and the electrodes by the oligomer addition was confirmed using a field-emission scanning electron microscope (FE-SEM). The electrolytes exhibited ionic conductivities on the order of 10^?4 S/cm, but PEGDGE electrolyte showed much lower value (～10^?8 S/cm). As a result, the energy conversion efficiency of DSSC was significantly affected by the oligomer. For example, the DSSC employing PEGDME with methyl terminal groups exhibited 3.95% at 100 mW/cm², which is 200-fold higher than that employing PEGDGE.     

Neuroprotective Effect of Statins in a Rat Model of Chronic Ocular Hypertension

Glaucoma is an optic neuropathy in which the degeneration of retinal ganglion cells (RGCs) results in irreversible vison loss. Therefore, neuroprotection of RGCs from glaucomatous afflictions is crucial for glaucoma treatment. In this study, we aimed to investigate the beneficial effects of statins in the protection of RGCs using a rat model. Glaucomatous injury was induced in rats by chronic ocular hypertension (OHT) achieved after performing a circumlimbal suture. The rats were given either statins such as simvastatin and atorvastatin or a solvent weekly for 6 weeks. Retina sections underwent hematoxylin and eosin, Brn3a, or cleaved casepase-3 staining to evaluate RGC survival. In addition, modulation of glial activation was assessed. While the retinas without statin treatment exhibited increased RGC death due to chronic OHT, statins promoted the survival of RGCs and reduced apoptosis. Statins also suppressed chronic OHT-mediated glial activation in the retina. Our results demonstrate that statins exert neuroprotective effects in rat retinas exposed to chronic OHT, which may support the prospect of statins being a glaucoma treatment.