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Revue Des Maladies Respiratoires Jun 2011The imaging techniques used to investigate patients with asthma and to assess the effects of asthma treatments include computed tomography (CT), helium magnetic... (Review)
Review
The imaging techniques used to investigate patients with asthma and to assess the effects of asthma treatments include computed tomography (CT), helium magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT), and positron-emission tomography (PET). Only MRI does not involve radiation exposure. Technical improvements in CT, together with the imaging advantages inherent in the presence of air in the lung, have diminished the radiation exposure required for lung CT. High-resolution low-dose lung CT protocols deliver a dose roughly equal to 1 year of natural radiation exposure and can be used even in paediatric patients. To date, CT is the most extensively studied lung imaging method, the simplest to perform, and the least expensive. In patients with asthma, CT may show several structural changes related to small-airway disease including cylindrical bronchiolectasis, bronchial wall thickening, and air trapping; an indirect marker for bronchiolar obstruction. A robust body of evidence indicates that valid CT markers for small-airway disease can be derived from quantitative lung density measurements and that these markers correlate with clinical severity and lung function test results. In addition, these CT markers are sufficiently sensitive to demonstrate therapeutic effects.
Topics: Air; Asthma; Bronchioles; Bronchography; Helium; Humans; Magnetic Resonance Imaging; Positron-Emission Tomography; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed
PubMed: 21742230
DOI: 10.1016/j.rmr.2011.05.001 -
Small (Weinheim An Der Bergstrasse,... Feb 2017Alarming levels of particulate matter pollution in air pose a serious health threat in several countries, therefore intriguing a strong need for an economic and a viable...
Alarming levels of particulate matter pollution in air pose a serious health threat in several countries, therefore intriguing a strong need for an economic and a viable technology of air filtration. Current air purification technology is rather expensive with certain types even having the risk of emitting hazardous by-products. The authors have developed a multifunctional air filter inspired from the nasal hairs possessing an ability to specifically trap/exhale the foreign particles and allergens while still letting the air flow. This design is achieved by introducing different functionalities at different dimensional scale employing a bottom-up approach starting with an organic molecule which is further self-organized to form nanoparticles and ultimately to a nanofibrous mesh. While the molecular building block inherently possesses the property of shielding Ultraviolet (UV) rays, the nanofibrous mesh built up from it aids in trapping the particulate matter while maintaining good air flow. By controlling the concentration of the organic molecule, the formation of fibers has been enabled in the nanoscale regime to obtain high particle-capture possibilities. The self-assembled nanofibrous filter thus designed has achieved a high filtration efficiency of ≈90% for the PM 2.5 particle in congruence with the ability to block the harmful UV radiations.
Topics: Air; Filtration; Nanofibers; Particulate Matter; Spectrophotometry, Ultraviolet
PubMed: 27911466
DOI: 10.1002/smll.201601924 -
Revue Des Maladies Respiratoires Jun 2013Pollen is a major cause of allergy and monitoring pollen in the air is relevant for diagnosis, treatment and prevention, as well as for biomedical and biological... (Review)
Review
INTRODUCTION
Pollen is a major cause of allergy and monitoring pollen in the air is relevant for diagnosis, treatment and prevention, as well as for biomedical and biological research. Many aero-biological studies have been conducted all over the world to ascertain aerial concentrations and seasonality of pollen grains.
BACKGROUND
Monitoring of airborne biological particles is carried out by various gravimetric, impaction, and suction sampling devices. The Hirst trap, later modified to Burkard(®) or Lanzoni(®) traps, is the most widely used sampler. Counting and identifying pollen grains is then performed under optical microscopy. Based on differences in airborne pollen recorded over several years of observation, pollen calendars have been drawn up as aids to allergy diagnosis and management but they could be replaced advantageously by allergy-risk calendars. Pollen counts also provide valuable information about the geographical origin of pollen grains.
VIEWPOINTS
Since the identifying and counting of pollen grains in ambient air samples is still a demanding and time-consuming task, there is an increasing interest in the automation of pollen monitoring. Furthermore, the divergence sometimes observed between clinical observations and pollen counts provides an incentive to collect aero-allergens directly. Lastly, pollen monitoring could be improved through the use of personal bioaerosol samplers.
CONCLUSIONS
Great progress has been made in aerobiology for over a century, but much remains to be accomplished, particularly in relation with the standardization of methods.
Topics: Air; Air Pollution; Allergens; Atmosphere; Environmental Monitoring; Humans; Pollen; Seasons; Specimen Handling
PubMed: 23835319
DOI: 10.1016/j.rmr.2013.02.006 -
Biophysical Journal Jul 2013Microbes inhabiting Earth have adapted to diverse environments of water, air, soil, and often at the interfaces of multiple media. In this study, we focus on the...
Microbes inhabiting Earth have adapted to diverse environments of water, air, soil, and often at the interfaces of multiple media. In this study, we focus on the behavior of Caulobacter crescentus, a singly flagellated bacterium, at the air/water interface. Forward swimming C. crescentus swarmer cells tend to get physically trapped at the surface when swimming in nutrient-rich growth medium but not in minimal salt motility medium. Trapped cells move in tight, clockwise circles when viewed from the air with slightly reduced speed. Trace amounts of Triton X100, a nonionic surfactant, release the trapped cells from these circular trajectories. We show, by tracing the motion of positively charged colloidal beads near the interface that organic molecules in the growth medium adsorb at the interface, creating a high viscosity film. Consequently, the air/water interface no longer acts as a free surface and forward swimming cells become hydrodynamically trapped. Added surfactants efficiently partition to the surface, replacing the viscous layer of molecules and reestablishing free surface behavior. These findings help explain recent similar studies on Escherichia coli, showing trajectories of variable handedness depending on media chemistry. The consistent behavior of these two distinct microbial species provides insights on how microbes have evolved to cope with challenging interfacial environments.
Topics: Adsorption; Air; Caulobacter crescentus; Microscopy; Movement; Surface Properties; Water
PubMed: 23823220
DOI: 10.1016/j.bpj.2013.05.026 -
Nature Communications Oct 2020Igniting and guiding electrical discharges to desired targets in the ambient atmosphere have been a subject of intense research efforts for decades. Ability to control...
Igniting and guiding electrical discharges to desired targets in the ambient atmosphere have been a subject of intense research efforts for decades. Ability to control discharge and its propagation can pave the way to a broad range of applications from nanofabrication and plasma medicine to monitoring of atmospheric pollution and, ultimately, taming lightning strikes. Numerous experiments utilizing powerful pulsed lasers with peak-intensity above air photoionization and photo-dissociation have demonstrated excitation and confinement of plasma tracks in the wakes of laser field. Here, we propose and demonstrate an efficient approach for triggering, trapping and guiding electrical discharges in air. It is based on the use of a low-power continuous-wave vortex beam that traps and transports light-absorbing particles in mid-air. We demonstrate a 30% decrease in discharge threshold mediated by optically trapped graphene microparticles with the use of a laser beam of a few hundred milliwatts of power. Our demonstration may pave the way to guiding electrical discharges along arbitrary paths.
PubMed: 33082327
DOI: 10.1038/s41467-020-19183-0 -
Accounts of Chemical Research Nov 2019Lead halide perovskite nanocrystals (NCs) have been widely studied for application in optoelectronic devices due to their excellent optical properties and low-cost...
Lead halide perovskite nanocrystals (NCs) have been widely studied for application in optoelectronic devices due to their excellent optical properties and low-cost synthesis. However, the toxicity of lead and the poor stability of the NCs hindered their practical applications. Sn-based perovskite with low toxicity was first developed; however, the Sn-based perovskite NCs are unstable in air and oxidize easily. Recently, air-stable lead-free perovskite NCs have been developed and received increasing attention. Unfortunately, the optical and optoelectronic properties of these lead-free halide perovskite NCs are generally far worse than those of lead-perovskite NCs. Understanding the charge-carrier dynamics of semiconductors is crucial to improve their optical properties. In this Account, we mainly review our recent research progress on the study of charge-carrier dynamics in air-stable lead-free perovskite NCs. The exciton trapping followed by nonradiative recombination was the major carrier relaxation pathway and resulted in a low photoluminescence quantum efficiency (PLQE). A feasible route for passivating surface traps and tuning the self-trapped excitons from "dark" (nonradiative) to "bright" (radiative) was proposed. Through this strategy, the PLQE could be increased over 100-fold. In addition, we have compared several photophysical properties of lead-free perovskite NCs with that of lead perovskite NCs, such as charge-carrier relaxation, exciton-phonon coupling, and hot-carrier cooling. In 2017, we reported the synthesis, optical properties, and charge-carrier dynamics of CsBiX (X: Cl, Br, I) NCs. The CsBiBr NCs exhibited clear exciton trapping processes with time scales in the range of 2-20 ps. The fast trapping processes could be passivated via the use of surfactants (such as oleic acid), and the PLQE increased over 20-fold (from 0.2% to 4.5%). The low PLQE may be due to the reduced dimensionality of CsBiBr (2D) compared with the 3D cubic perovskite structure of CsPbBr. We next reported double perovskite CsAgSbBiX (X: Br, Cl; 0 ≤ ≤ 1) NCs, which exhibited a similar 3D cubic perovskite structure to that of the lead-perovskite NCs. The charge-carrier dynamics indicated that the sub-band-gap exciton trapping processes were dominated by ultrafast (∼1-2 ps) intrinsic self-trapping and trapping at surface defects (∼50-100 ps). While trapping at surface defects can be passivated using surfactants, the self-trapping processes is due to the giant carrier-phonon coupling effect. By designing direct band gap double perovskite NCs to tune the sub-band-gap trapping processes, bright dual-color emission was achieved. Furthermore, the violet PLQE could be improved to 36.6%, which is comparable to that in lead halide perovskite NCs. We hope this Account will deepen the understanding of the charge-carrier dynamics in lead-free perovskite NCs and guide the design of high-performance lead-free perovskites.
PubMed: 31664815
DOI: 10.1021/acs.accounts.9b00422 -
Journal of Microelectromechanical... Oct 2020This paper describes a novel acoustic transducer with dual functionality based on 1-mm-thick lead zirconate titanate (PZT) substrate with a modified air-cavity Fresnel...
This paper describes a novel acoustic transducer with dual functionality based on 1-mm-thick lead zirconate titanate (PZT) substrate with a modified air-cavity Fresnel acoustic lens on top. Designed to let ultrasound waves focus over an annular ring region, the lens generates a long depth-of-focus Bessel-like focal beam and multiple trapping zones based on quasi-Airy beams and bottle beams. With 2.32 MHz sinusoidal driving signal at 150 V, the transducer produces a focal zone with 9.9 mm depth-of-focus and 0.8 MPa peak pressure at a focal length of 31.33 mm. With 2.32 MHz continuous sinusoidal drive at 30-35 V, the transducer is able to trap multiple polyethylene microspheres (350-1,000 m in diameter and 1.025-1.130 g/cm in density) in water either simultaneously (when suspended by mechanical agitation or released from water surface) or sequentially (when placed one after another with a pipette). The largest particles the transducer could trap are two 1-mm-diameter microspheres stuck together (1.07 mg in weight, lifted by buoyance and 0.257 N acoustic-field-induced force). When the transducer is moved laterally, some firmly trapped microspheres follow along the transducer's movement, while being trapped. When trapped, some microspheres can rotate due to the rotation torque generated by the quasi-Airy beams.
PubMed: 33746473
DOI: 10.1109/jmems.2020.3000715 -
Journal of the American Mosquito... Mar 2023The most prevalent insect sampling and surveillance problem is powering insect traps in the field. Most modern light traps use 6-V power supplies such as the Centers for...
The most prevalent insect sampling and surveillance problem is powering insect traps in the field. Most modern light traps use 6-V power supplies such as the Centers for Disease Control and Prevention (CDC) suction trap. Buck converter modules efficiently reduce 12-V direct current power to 6-V, which permits the use of higher voltage batteries with lower voltage traps, resulting in longer operational duration and reduced labor requirements associated with replacing and recharging batteries in the field. We evaluated several battery configurations of 6- and 12-V lead-acid batteries in various sizes (10-20 ampere-hours) and addressed, in the circuit design, common problems that occur when using the buck converter (such as crossing polarity and excessive battery depletion). The efficacy of each configuration was assessed by measuring the voltage and suction while powering a 6-V CDC light trap. The buck converter permitted the use of cheaper and more commonly available 12-V batteries to run the CDC light traps and resulted in longer effective operation time as measured by air speed.
Topics: United States; Time Factors; Mosquito Control
PubMed: 36657062
DOI: 10.2987/22-7061 -
A rotatory funnel-shaped collector for trapping airborne mites in a glycerin-based adhesive surface.Experimental & Applied Acarology Feb 2022Many mite species disperse via the air. However, most methods described for the study of aerial dispersal have some limitations in the collection and/or recovery of...
Many mite species disperse via the air. However, most methods described for the study of aerial dispersal have some limitations in the collection and/or recovery of mites that could be improved. The aim of this study was to describe a rotatory funnel-shaped collector that directs the wind to adhesive surfaces covered with a glycerin-based solution. Tests were conducted on a soccer field at UESC, Ilhéus, Brazil, in four 8-day periods. In total, 330 mites of 52 species of Eriophyidae, Tarsonemidae, Diptilomiopidae, Iolinidae, Triophtydeidae, Astigmata, Tydeidae, Phytoseiidae, Scutacaridae, Oribatida, Ascidae, Dolichocybidae, Eupodidae, Pygmephoridae and Tenuipalpidae were collected. Of the mites captured in the first three periods, 67% were Aceria sp. (Eriophyidae), and in the fourth period 46% were Coccotydaeolus aff. bakeri and Paurotyndareus sp. (Iolinidae). Comparisons between the funnel-shaped collector with the tube-shaped rotatable model of Duffner et al. (J Pest Sci 74:1-6, 2001, adapted from Schliesske 1977) showed that the former captured >3× the number of mites and 2× the number of species. In conclusion, it is expected that the method described here could help in future pest management, and help solve ecological and behavioral problems involving airborne mite dispersal, offering a tool for monitoring, counting and identifying mites, or even other small arthropods, pollen and fungal spores, in experimental and applied studies.
Topics: Adhesives; Animals; Brazil; Glycerol; Mites; Wind
PubMed: 35038078
DOI: 10.1007/s10493-022-00687-x -
American Journal of Physiology. Cell... Sep 2011Gas embolism is a serious complication of decompression events and clinical procedures, but the mechanism of resulting injury remains unclear. Previous work has...
Gas embolism is a serious complication of decompression events and clinical procedures, but the mechanism of resulting injury remains unclear. Previous work has demonstrated that contact between air microbubbles and endothelial cells causes a rapid intracellular calcium transient and can lead to cell death. Here we examined the mechanism responsible for the calcium rise. Single air microbubbles (50-150 μm), trapped at the tip of a micropipette, were micromanipulated into contact with individual human umbilical vein endothelial cells (HUVECs) loaded with Fluo-4 (a fluorescent calcium indicator). Changes in intracellular calcium were then recorded via epifluorescence microscopy. First, we confirmed that HUVECs rapidly respond to air bubble contact with a calcium transient. Next, we examined the involvement of extracellular calcium influx by conducting experiments in low calcium buffer, which markedly attenuated the response, or by pretreating cells with stretch-activated channel blockers (gadolinium chloride or ruthenium red), which abolished the response. Finally, we tested the role of intracellular calcium release by pretreating cells with an inositol 1,4,5-trisphosphate (IP3) receptor blocker (xestospongin C) or phospholipase C inhibitor (neomycin sulfate), which eliminated the response in 64% and 67% of cases, respectively. Collectively, our results lead us to conclude that air bubble contact with endothelial cells causes an influx of calcium through a stretch-activated channel, such as a transient receptor potential vanilloid family member, triggering the release of calcium from intracellular stores via the IP3 pathway.
Topics: Adenosine Triphosphate; Air; Calcium Channel Blockers; Calcium Signaling; Cells, Cultured; Cytochalasin D; Embolism, Air; Endoplasmic Reticulum; Gadolinium; Human Umbilical Vein Endothelial Cells; Humans; Inositol 1,4,5-Trisphosphate; Inositol 1,4,5-Trisphosphate Receptors; Ionomycin; Macrocyclic Compounds; Microbubbles; Neomycin; Oxazoles; Ruthenium Red; Signal Transduction; TRPV Cation Channels; Type C Phospholipases
PubMed: 21633077
DOI: 10.1152/ajpcell.00046.2011