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Ultrafine particles

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https://www.readbyqxmd.com/read/29346707/tuning-high-temperature-wetting-behavior-of-metal-toward-ultrafine-nanoparticles
#1
Yubing Zhou, Bharath Natarajan, Yanchen Fan, Hua Xie, Chunpeng Yang, Shaomao Xu, Yonggang Yao, Feng Jiang, Qianfan Zhang, Jeffrey W Gilman, Liangbing Hu
The interaction between the metal nanoparticles and their substrate plays a critical role in determining the particle morphology, distribution, and properties. Here we present the pronounced impact of a thin oxide coating to the dispersion of metal nanoparticles on a carbon matrix. We employ Al2O3-supported Pt nanoparticles in comparison with direct synthesis of Pt nanoparticles on bare carbon surfaces. Pt nanoparticles with an average size of ≈2 nm and a size distribution ranging between 0.5 nm and 4.0 nm are synthesized on the Al2O3 coated carbon nanofiber, significantly improved compared to those directly synthesized on bare carbon surface...
January 18, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29333080/comparisons-of-traffic-related-ultrafine-particle-number-concentrations-measured-in-two-urban-areas-by-central-residential-and-mobile-monitoring
#2
Matthew C Simon, Neelakshi Hudda, Elena N Naumova, Jonathan I Levy, Doug Brugge, John L Durant
Traffic-related ultrafine particles (UFP; <100 nanometers diameter) are ubiquitous in urban air. While studies have shown that UFP are toxic, epidemiological evidence of health effects, which is needed to inform risk assessment at the population scale, is limited due to challenges of accurately estimating UFP exposures. Epidemiologic studies often use empirical models to estimate UFP exposures; however, the monitoring strategies upon which the models are based have varied between studies. Our study compares particle number concentrations (PNC; a proxy for UFP) measured by three different monitoring approaches (central-site, short-term residential-site, and mobile on-road monitoring) in two study areas in metropolitan Boston (MA, USA)...
November 2017: Atmospheric Environment
https://www.readbyqxmd.com/read/29327287/study-of-effect-of-impacting-direction-on-abrasive-nanometric-cutting-process-with-molecular-dynamics
#3
Junye Li, Wenqing Meng, Kun Dong, Xinming Zhang, Weihong Zhao
Abrasive flow polishing plays an important part in modern ultra-precision machining. Ultrafine particles suspended in the medium of abrasive flow removes the material in nanoscale. In this paper, three-dimensional molecular dynamics (MD) simulations are performed to investigate the effect of impacting direction on abrasive cutting process during abrasive flow polishing. The molecular dynamics simulation software Lammps was used to simulate the cutting of single crystal copper with SiC abrasive grains at different cutting angles (0o-45o)...
January 11, 2018: Nanoscale Research Letters
https://www.readbyqxmd.com/read/29323609/e-cigarettes-use-effects-on-smoking-risks-and-policy-implications
#4
Stanton A Glantz, David W Bareham
Since e-cigarettes appeared in the mid-2000s, some practitioners, researchers, and policy makers have embraced them as a safer alternative to conventional cigarettes and an effective way to stop smoking. While e-cigarettes deliver lower levels of carcinogens than do conventional cigarettes, they still expose users to high levels of ultrafine particles and other toxins that may substantially increase cardiovascular and noncancer lung disease risks, which account for more than half of all smoking-caused deaths, at rates similar to conventional cigarettes...
January 11, 2018: Annual Review of Public Health
https://www.readbyqxmd.com/read/29319630/exposure-to-ambient-ultrafine-particles-and-nitrogen-dioxide-and-incident-hypertension-and-diabetes
#5
Li Bai, Hong Chen, Marianne Hatzopoulou, Michael Jerrett, Jeffrey C Kwong, Richard T Burnett, Aaron van Donkelaar, Ray Copes, Randall V Martin, Keith van Ryswyk, Hong Lu, Alexander Kopp, Scott Weichenthal
BACKGROUND: Previous studies reported that long-term exposure to traffic-related air pollution may increase the incidence of hypertension and diabetes. However, little is known about the associations of ultrafine particles (≤0.1 micrometers in diameter) with these two conditions. METHODS: We conducted a population-based cohort study to investigate the associations between exposures to ultrafine particles and nitrogen dioxide (NO2) and the incidence of diabetes and hypertension...
January 9, 2018: Epidemiology
https://www.readbyqxmd.com/read/29306190/anchoring-ultrafine-pd-nanoparticles-and-sno2-nanoparticles-on-reduced-graphene-oxide-for-high-performance-room-temperature-no2-sensing
#6
Ziying Wang, Tong Zhang, Chen Zhao, Tianyi Han, Teng Fei, Sen Liu, Geyu Lu
In this paper, we demonstrate room-temperature NO2 gas sensors using Pd nanoparticles (NPs) and SnO2 NPs decorated reduced graphene oxide (Pd-SnO2-RGO) hybrids as sensing materials. It is found that ultrafine Pd NPs and SnO2 NPs with particle sizes of 3-5 nm are attached to RGO nanosheets. Compared to SnO2-RGO hybrids, the sensor based on Pd-SnO2-RGO hybrids exhibited higher sensitivity at room temperature, where the response to 1 ppm NO2 was 3.92 with the response time and recovery time being 13 s and 105 s...
December 28, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/29302961/emission-rates-of-multiple-air-pollutants-generated-from-chinese-residential-cooking
#7
Chen Chen, Yuejing Zhao, Bin Zhao
Household air pollution generated from cooking is severe, especially for Chinese-style cooking. We measured the emission rates of multiple air pollutants including fine particles (PM2.5), ultrafine particles (UFPs), and volatile organic compounds (VOCs, including formaldehyde, benzene, and toluene) that were generated from typical Chinese cooking in a residential kitchen. The experiment was designed through five-factor and five-level orthogonal testing. The five key factors were cooking method, ingredient weight, type of meat, type of oil, and meat/vegetable ratio...
January 5, 2018: Environmental Science & Technology
https://www.readbyqxmd.com/read/29279616/cytocompatibility-of-a-self-adhesive-gutta-percha-root-filling-material
#8
Joyce Nascimento, Miriam Zaccaro Scelza, Gutemberg Gomes Alves, Adriana Linhares, Antonio Canabarro, Jose Mauro Granjeiro, Gustavo De-Deus
Context: A novel root-filling material based on the incorporation of ultrafine alkaline bioactive glass particles (bioactive gutta-percha, [BGP]) was developed to work without sealer. Aim: In the present study, the objective was to verify the in vitro biological response to this material by assessing its cytocompatibility. Materials and Methods: Prototypes of BGP were compared to conventional gutta-percha (GP), dense polystyrene beads as a negative control and fragments of latex as a positive control...
May 2017: Journal of Conservative Dentistry: JCD
https://www.readbyqxmd.com/read/29276956/oxygen-content-determines-the-bio-reactivity-and-toxicity-profiles-of-carbon-black-particles
#9
Yakun Wu, Yifan Guo, Haoyang Song, Wei Liu, Yi Yang, Yajun Liu, Nan Sang, Yi Y Zuo, Sijin Liu
In spite of the considerable efforts invested to understand the environmental health and safety (EHS) impacts of ultrafine particles, such as the representative PM2.5, there are still significant knowledge gaps to be filled. No conclusive understandings have been obtained about the physicochemical determinants in accounting for differential adverse outcomes. Here we compared the cytotoxicity of four carbon black (CB) particles with similar physicochemical properties except for their oxygen contents (C824455 < C1864 < Printex U < SB4A)...
December 22, 2017: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/29261158/real-time-measurements-and-characterization-of-airborne-particulate-matter-from-a-primary-silicon-carbide-production-plant
#10
Rikke Bramming Jørgensen, Ida Teresia Kero
Airborne particulate matter in the silicon carbide (SiC) industry is a known health hazard. The aims of this study were to elucidate whether the particulate matter generated inside the Acheson furnace during active operation is representative of the overall particulate matter in the furnace hall, and whether the Acheson furnaces are the main sources of ultrafine particles (UFP) in primary SiC production. The number concentration of ultrafine particles was evaluated using an Electrical Low Pressure Impactor (ELPITM, Dekati Ltd...
December 20, 2017: International Journal of Environmental Research and Public Health
https://www.readbyqxmd.com/read/29247674/developmental-exposure-to-low-level-ambient-ultrafine-particle-air-pollution-and-cognitive-dysfunction
#11
D A Cory-Slechta, J L Allen, K Conrad, E Marvin, M Sobolewski
Developmental exposures to ambient ultrafine particles (UFPs) can produce multiple neuropathological and neurochemical changes that might contribute to persistent alterations in cognitive-type functions. The objective of the current study was to test the hypothesis that developmental UFP exposure produced impairments in learning, memory and impulsive-like behaivors and to determine whether these were selective and thus independent of deficits in other behavioral domains such as motor activity or motivation...
December 13, 2017: Neurotoxicology
https://www.readbyqxmd.com/read/29245060/activation-of-human-eosinophils-with-palladium-nanoparticles-pd-nps-importance-of-the-actin-cytoskeleton-in-pd-nps-induced-cellular-adhesion
#12
P Chhay, M Murphy-Marion, Y Samson, D Girard
Palladium (Pd) is known to be released into the environment in the fine and ultrafine (at the nanoscale) airborne particle fractions mainly from automobile catalytic converters leading to an increase human exposure to this noble metal. It was reported that Pd can induce allergic reactions in individuals exposed to it via different ways. Some studies reported an increased number of eosinophils into airways following NP exposure in vivo in rodent models of allergies and inflammation. Knowing the importance of eosinophils in allergies, asthma and other lung diseases, it is surprising to observe that the direct effect of Pd at the nanoscale in eosinophils has been poorly documented...
December 11, 2017: Environmental Toxicology and Pharmacology
https://www.readbyqxmd.com/read/29244949/growth-kinetics-and-size-distribution-dynamics-of-viscous-secondary-organic-aerosol
#13
Rahul A Zaveri, John E Shilling, Alla Zelenyuk, Jiumeng Liu, David M Bell, Emma L D'Ambro, Cassandra J Gaston, Joel A Thornton, Alexander Laskin, Peng Lin, Jacqueline M Wilson, Richard C Easter, Jian Wang, Allan K Bertram, Scot T Martin, John H Seinfeld, Douglas R Worsnop
Low bulk diffusivity inside viscous semisolid atmospheric secondary organic aerosol (SOA) can prolong equilibration timescale, but its broader impacts on aerosol growth and size distribution dynamics are poorly understood. Here we present quantitative insights into the effects of bulk diffusivity on the growth and evaporation kinetics of SOA formed under dry conditions from photooxidation of isoprene in the presence of a bimodal aerosol consisting of Aitken (ammonium sulfate) and accumulation (isoprene or -pinene SOA) mode particles...
December 15, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/29241004/intrinsic-size-effect-in-scaffolded-porous-calcium-silicate-particles-and-mechanical-behavior-of-their-self-assembled-ensembles
#14
Sung Hoon Hwang, Rouzbeh Shahsavari
Scaffolded porous submicron particles with well-defined diameter, shape and pore size have profound impacts in drug delivery, bone-tissue replacement, catalysis, sensors, photonic crystals and self-healing materials. However, understanding the interplay between pore size, particle size, and mechanical properties of such ultrafine particles, specially at the level of individual particles and their ensemble states, is a challenge. Herein, we focus on porous calcium-silicate submicron particles with various diameters - as a model system - and perform an extensive 900+ nanoindentations to completely map out their mechanical properties at three distinct structural forms from individual submicron particles to self-assembled ensembles to pressure-induced assembled arrays...
December 14, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29230439/ex-vivo-detection-and-quantification-of-gold-nanoparticles-in-human-seminal-and-follicular-fluids
#15
Dimitrios Bitounis, Jean-Philippe Klein, Lionel Mery, Amira El-Merhie, Valérie Forest, Delphine Boudard, Jérémie Pourchez, Michèle Cottier
Increasing consumption of engineered nanoparticles and occupational exposure to novel, ultrafine airborne particles during the last decades has coincided with deterioration of sperm parameters and delayed fecundity. In order to prevent possible adverse health effects and ensure a sustainable growth for the nanoparticle industry, the ability to investigate the nanosized, mineralogical load of human reproductive systems is becoming a real clinical need. Toward this goal, the current study proposes two methods for the detection and quantification of engineered nanoparticles in human follicular and seminal fluid, developed with the use of well-defined 60 nm Au particles...
December 12, 2017: Analyst
https://www.readbyqxmd.com/read/29221643/respiratory-and-cardiovascular-responses-to-walking-down-a-traffic-polluted-road-compared-with-walking-in-a-traffic-free-area-in-participants-aged-60-years-and-older-with-chronic-lung-or-heart-disease-and-age-matched-healthy-controls-a-randomised-crossover
#16
Rudy Sinharay, Jicheng Gong, Benjamin Barratt, Pamela Ohman-Strickland, Sabine Ernst, Frank Kelly, Junfeng Jim Zhang, Peter Collins, Paul Cullinan, Kian Fan Chung
BACKGROUND: Long-term exposure to pollution can lead to an increase in the rate of decline of lung function, especially in older individuals and in those with chronic obstructive pulmonary disease (COPD), whereas shorter-term exposure at higher pollution levels has been implicated in causing excess deaths from ischaemic heart disease and exacerbations of COPD. We aimed to assess the effects on respiratory and cardiovascular responses of walking down a busy street with high levels of pollution compared with walking in a traffic-free area with lower pollution levels in older adults...
December 5, 2017: Lancet
https://www.readbyqxmd.com/read/29216464/traffic-pollutants-measured-inside-vehicles-waiting-in-line-at-a-major-us-mexico-port-of-entry
#17
Penelope J E Quintana, Mehdi Khalighi, Javier Emmanuel Castillo Quiñones, Zalak Patel, Jesus Guerrero Garcia, Paulina Martinez Vergara, Megan Bryden, Antoinette Mantz
At US-Mexico border Ports of Entry, vehicles idle for long times waiting to cross northbound into the US. Long wait times at the border have mainly been studied as an economic issue, however, exposures to emissions from idling vehicles can also present an exposure risk. Here we present the first data on in-vehicle exposures to driver and passengers crossing the US-Mexico border at the San Ysidro, California Port of Entry (SYPOE). Participants were recruited who regularly commuted across the border in either direction and told to drive a scripted route between two border universities, one in the US and one in Mexico...
December 4, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/29215038/differential-raman-backscattering-cross-sections-of-black-carbon-nanoparticles
#18
Kim Cuong Le, Christophe Lefumeux, Thomas Pino
We report the measurements of the differential Raman backscattering cross sections for several carbonaceous ultrafine particles of environmental relevances. These were obtained by dispersing the target particles in liquid water which was used as the internal standard reference. The optical collection was performed in a configuration to ensure a detection as close as possible to the backward direction. These are the first cross sections on black carbon-type particles although Raman spectroscopy is widely used in Carbon science...
December 7, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29207286/short-term-effects-of-ultrafine-particles-on-daily-mortality-by-primary-vehicle-exhaust-versus-secondary-origin-in-three-spanish-cities
#19
Aurelio Tobías, Ioar Rivas, Cristina Reche, Andrés Alastuey, Sergio Rodríguez, Rocío Fernández-Camacho, Ana M Sánchez de la Campa, Jesús de la Rosa, Jordi Sunyer, Xavier Querol
BACKGROUND: Evidence on the short-term effects of ultrafine particles (with diameter<100nm, UFP) on health is still inconsistent. New particles in ambient urban air are the result of direct emissions and also the formation of secondary UFP from gaseous precursors. We segregated UFP into these two components and investigated their impact on daily mortality in three Spanish cities affected by different sources of air pollution. METHODS: We separated the UFP using a method based on the high correlation between black carbon (BC) and particle number concentration (N)...
December 2, 2017: Environment International
https://www.readbyqxmd.com/read/29205948/ultrafine-vs4-nanoparticles-anchored-on-graphene-sheets-as-a-high-rate-and-stable-electrode-material-for-sodium-ion-batteries
#20
Qiang Pang, Yingying Zhao, Yanhao Yu, Xiaofei Bian, Xudong Wang, Yingjin Wei, Yu Gao, Gang Chen
Size and conductivity of the electrode materials play a significant role in improving the kinetics of sodium ion batteries. Various characterizations demonstrate that size-controllable VS4 nanoparticles are successfully anchored on graphene sheets (GS) surfaces by a simple cationic surfactant-assisted hydrothermal method. When used as an electrode material for sodium ion batteries, these VS4/GS nanocomposites show large specific capacity (349.1 mA∙h∙g-1 after 100 cycles), excellent long-term stability (84% capacity retention after 1200 cycles), and high rate capability (188...
December 4, 2017: ChemSusChem
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