Urinary Levoglucosan as a Biomarker for Wood Smoke: Results of Human Exposure Studies

Urinary levoglucosan was investigated as a potential biomarker for wood smoke exposure in two different controlled experimental settings. Nine subjects were exposed to smoke from a campfire in a controlled setting and four were exposed to smoke from an older model wood stove. All subjects were asked to provide urine samples before and after exposure, and to wear personal PM2.5 monitors during the exposure. Urinary levoglucosan measurements from both studies showed no consistent response to the smoke exposure. A third experiment was conducted to assess the contribution of dietary factors to urinary levoglucosan levels. Nine subjects were asked to consume caramel and provide urine samples before and after consumption. Urinary levoglucosan levels increased within 2 hours of caramel consumption and returned to pre-exposure levels within 24 hours. These studies suggest that diet is a major factor in determining urinary levoglucosan levels and recent dietary history needs to be taken into account for future work involving levoglucosan as a biomarker of wood smoke exposure

Urinary Levoglucosan as a Biomarker of Wood Smoke Exposure: Observations in a Mouse Model and in Children

BACKGROUND: Biomass smoke is an important source of particulate matter (PM), and much remains to be discovered with respect to the human health effects associated with this specific PM source. Exposure to biomass smoke can occur in one of two main categories: short-term exposures consist of periodic, seasonal exposures typified by communities near forest fires or intentional agricultural burning, and long-term exposures are chronic and typified by the use of biomass materials for cooking or heating. Levoglucosan (LG), a sugar anhydride released by combustion of cellulose-containing materials, is an attractive candidate as a biomarker of wood smoke exposure. OBJECTIVES: In the present study, Balb/c mice and children were assessed for LG in urine to determine its feasibility as a biomarker. METHODS: We performed urinary detection of LG by gas chromatography/mass spectrometry after intranasal instillations of LG or concentrated PM (mice) or biomass exposure (mice or humans). RESULTS: After instillation, we recovered most of the LG within the first 4 hr. Experiments using glucose instillation proved the specificity of our system, and instillation of concentrated PM from wood smoke, ambient air, and diesel exhaust supported a connection between wood smoke and LG. In addition, LG was detected in the urine of mice exposed to wood smoke. Finally, a pilot human study proved our ability to detect LG in urine of children. CONCLUSIONS: These results demonstrate that LG in the lungs is detectable in the urine of both mice and humans and that it is a good candidate as a biomarker of exposure to biomass smoke

Planck 2013 results. VI. High Frequency Instrument data processing

We describe the processing of the 531 billion raw data samples from the High Frequency Instrument (HFI), which we performed to produce six temperature maps from the first 473 days of Planck-HFI survey data. These maps provide an accurate rendition of the sky emission at 100, 143, 217, 353, 545, and 857GHz with an angular resolution ranging from 9.́7 to 4.́6. The detector noise per (effective) beam solid angle is respectively, 10, 6 , 12, and 39 μK in the four lowest HFI frequency channels (100−353GHz) and 13 and 14 kJy sr-1 in the 545 and 857 GHz channels. Relative to the 143 GHz channel, these two high frequency channels are calibrated to within 5% and the 353 GHz channel to the percent level. The 100 and 217 GHz channels, which together with the 143 GHz channel determine the high-multipole part of the CMB power spectrum (50 <ℓ < 2500), are calibrated relative to 143 GHz to better than 0.2%

Cold atoms in space: community workshop summary and proposed road-map

We summarise the discussions at a virtual Community Workshop on Cold Atoms in Space concerning the status of cold atom technologies, the prospective scientific and societal opportunities offered by their deployment in space, and the developments needed before cold atoms could be operated in space. The cold atom technologies discussed include atomic clocks, quantum gravimeters and accelerometers, and atom interferometers. Prospective applications include metrology, geodesy and measurement of terrestrial mass change due to, e.g., climate change, and fundamental science experiments such as tests of the equivalence principle, searches for dark matter, measurements of gravitational waves and tests of quantum mechanics. We review the current status of cold atom technologies and outline the requirements for their space qualification, including the development paths and the corresponding technical milestones, and identifying possible pathfinder missions to pave the way for missions to exploit the full potential of cold atoms in space. Finally, we present a first draft of a possible road-map for achieving these goals, that we propose for discussion by the interested cold atom, Earth Observation, fundamental physics and other prospective scientific user communities, together with the European Space Agency (ESA) and national space and research funding agencies

Cold atoms in space: community workshop summary and proposed road-map

We summarise the discussions at a virtual Community Workshop on Cold Atoms in Space concerning the status of cold atom technologies, the prospective scientific and societal opportunities offered by their deployment in space, and the developments needed before cold atoms could be operated in space. The cold atom technologies discussed include atomic clocks, quantum gravimeters and accelerometers, and atom interferometers. Prospective applications include metrology, geodesy and measurement of terrestrial mass change due to, e.g., climate change, and fundamental science experiments such as tests of the equivalence principle, searches for dark matter, measurements of gravitational waves and tests of quantum mechanics. We review the current status of cold atom technologies and outline the requirements for their space qualification, including the development paths and the corresponding technical milestones, and identifying possible pathfinder missions to pave the way for missions to exploit the full potential of cold atoms in space. Finally, we present a first draft of a possible road-map for achieving these goals, that we propose for discussion by the interested cold atom, Earth Observation, fundamental physics and other prospective scientific user communities, together with the European Space Agency (ESA) and national space and research funding agencies

Evaporative transport in thin liquid films and electrically actuated droplets

The basis of operation for two-phase devices such as heat pipes and vapor chambers is phase change heat transfer from a meniscus in a wetted wick structure. The heat transport capability of the device largely depends on the characteristics of the meniscus very near the contact line, termed the thin-film region. Only recently have measurement techniques matured to the point where the hydrodynamic and thermal characteristics of thin liquid films can be probed. The present work reports on the use of high-resolution temporal, spatial, and thermographic measurements to describe transport phenomena of liquid films and droplets in fundamentally critical configurations. Non-contact microscale infrared thermography is employed to directly measure the temperature of a V-groove wetted by an evaporating meniscus. A temperature suppression in the vicinity of the contact line is clear evidence of the intensive evaporation occurring in the thin-film region. A 50 μm long meniscus sub-region adjacent to the contact line is estimated from the experiments to account for ∼ 45% of the total meniscus heat transfer. Similarly, an evaporating meniscus wetting a bed of spheres in a carefully instrumented, saturated-ambient chamber is examined. A kinetic-theory based numerical algorithm reveals that up to ∼ 55% of the total meniscus mass transfer is attributable to a meniscus sub-region of \u3c10 μm thickness (sub-region length typically ∼ 30 μm). In both cases, microregions with length scales on the order of tens of μm account for \u3c 5% of the total meniscus surface area, but contribute roughly half of the total heat and mass transport, demonstrating that high-performance thermal systems should be designed to exploit the superior heat transfer rates supported by thin-film evaporation. Droplet-based thermal management techniques offer precise spatial and temporal control, making them ideal for cooling hot spots or other high heat density systems. The manipulation of liquid droplets by electrowetting on superhydrophobic surfaces is a well-studied technique that has recently been applied to thermal management systems. The present work describes a fundamental investigation of the dissipative effects in the electrowetting-induced Cassie-Wenzel transition of droplets on hydrophobic rough surfaces. The droplet shape evolution during the transition is recorded by high-speed imaging (at 10,000 frames per second). A quantitative surface energy-based analysis suggests that contact line friction—the dominant dissipative mechanism for droplets spreading on smooth surfaces—is overshadowed by other viscous and/or hysteresis effects on hydrophobic rough surfaces. Additionally, the influence of surface patterning and electrowetting-induced spreading on the heat transfer and contact line dynamics of narrow water ribbons on a heated surface is reported. Chemical and structural patterning of the surface constrains water to a ribbon shape in the absence of electrical actuation. Liquid ribbons spread under electrical actuation are able to sustain higher evaporation rates and provide a more pronounced cooling effect than ribbons without actuation. The spatial selectivity offered by the concept may prove useful for future on-chip thermal management systems

Temperature measurements near the contact line of an evaporating meniscus V-groove

Evaporation from a meniscus of heptane liquid in a V-groove geometry is experimentally investigated. A thin layer of titanium coated on the backside of the fused quartz groove is electrically heated to provide a constant heat flux. The temperature profile in the evaporating thin film region of the extended meniscus is measured using high-resolution infrared thermography and the temperature suppression in this region is obtained as a function of liquid feeding rate. The meniscus shape is captured using a goniometer. A temperature suppression of ~0.2 K in the 150 micrometers region surrounding the contact line on each side indicates the efficacy of evaporation in the extended meniscus. At a given axial location, the fraction of total meniscus heat transfer which takes place in a 50 micrometer sub-region measured from the contact line is estimated by an approximate heat balance analysis to be ~45% for the range of liquid feeding rates explored

Microscale Temperature Measurements near the Contact Line of an Evaporating Thin Film in a V-Groove

Thin-film evaporation of heptane in a V-groove geometry is experimentally investigated. The groove is made of fused quartz, and electrical heating of a thin layer of titanium coated on the backside of the quartz substrate provides a constant heat flux. The effects of liquid feeding rate on the temperature suppression in the thin-film region and on the meniscus shape are explored. High resolution (∼6.3 μm) infrared thermography is employed to investigate the temperature profile in the thin-film region, while a goniometer is used to image the meniscus shape. An approximate heat balance analysis is used to estimate the fraction of total meniscus heat transfer which takes place in the contact line region

Evaporative Heat and Mass Transfer from the Free Surface of a Liquid Wicked into a Bed of Spheres

Evaporation of ethanol from square packed arrays of 3.95 mm diameter copper spheres in a transparent, enclosed chamber is investigated. The enclosure ensures that relatively saturated vapor conditions exist near the free surface. The desired heat flux is imposed on the copper substrate upon which the copper spheres are mounted, and the liquid level in the bed is maintained by wicking from a continuous supply of liquid provided by a syringe pump. Transparent windows in the enclosure allow for visualization of theevaporating liquid meniscus shape, which is recorded for different liquid feeding rates and heat fluxes. Experimentally measured meniscus profiles are compared to analytical results based on surface-energy minimization. A meniscus microregion is defined from the contact line to the length where the liquid thickness reaches 10 lm. An approximate kinetic theory-based analysis estimates that up to 55% of the total meniscus mass transfer occurs in this microregion

Dissipative Forces in the Electrowetted Cassie-Wenzel Transition on Hydrophobic Rough Surfaces

Dissipative forces in the electrowetting-induced Cassie-Wenzel transition on hydrophobic rough surfaces are explored. High-speed imaging of droplet shape evolution during the elec- trically induced spreading process allows for the location of the contact line to be tracked as a function of time. A surface energy analysis quantifies the total energy dissipated via nonconservative forces during the spreading process. Though identified as the dominant dissipative effect in droplet spreading on smooth surfaces, contact line friction is shown to have a relatively weak influence on the spreading on rough surfaces. Supplemental files are available for this article. Go to the publisher’s online edition of Nanoscale and Microscale Thermophysical Engineering to view the free supplemental file