WorldWideScience

Sample records for amplify ultrafine particle

  1. Environmentally persistent free radicals amplify ultrafine particle mediated cellular oxidative stress and cytotoxicity

    Directory of Open Access Journals (Sweden)

    Balakrishna Shrilatha

    2009-04-01

    Full Text Available Abstract Background Combustion generated particulate matter is deposited in the respiratory tract and pose a hazard to the lungs through their potential to cause oxidative stress and inflammation. We have previously shown that combustion of fuels and chlorinated hydrocarbons produce semiquinone-type radicals that are stabilized on particle surfaces (i.e. environmentally persistent free radicals; EPFRs. Because the composition and properties of actual combustion-generated particles are complex, heterogeneous in origin, and vary from day-to-day, we have chosen to use surrogate particle systems. In particular, we have chosen to use the radical of 2-monochlorophenol (MCP230 as the EPFR because we have previously shown that it forms a EPFR on Cu(IIO surfaces and catalyzes formation of PCDD/F. To understand the physicochemical properties responsible for the adverse pulmonary effects of combustion by-products, we have exposed human bronchial epithelial cells (BEAS-2B to MCP230 or the CuO/silica substrate. Our general hypothesis was that the EPFR-containing particle would have greater toxicity than the substrate species. Results Exposure of BEAS-2B cells to our combustion generated particle systems significantly increased reactive oxygen species (ROS generation and decreased cellular antioxidants resulting in cell death. Resveratrol treatment reversed the decline in cellular glutathione (GSH, glutathione peroxidase (GPx, and superoxide dismutase (SOD levels for both types of combustion-generated particle systems. Conclusion The enhanced cytotoxicity upon exposure to MCP230 correlated with its ability to generate more cellular oxidative stress and concurrently reduce the antioxidant defenses of the epithelial cells (i.e. reduced GSH, SOD activity, and GPx. The EPFRs in MCP230 also seem to be of greater biological concern due to their ability to induce lipid peroxidation. These results are consistent with the oxidizing nature of the CuO/silica ultrafine

  2. Ultrafine particles in the atmosphere

    CERN Document Server

    Brown, L M; Harrison, R M; Maynard, A D; Maynard, R L

    2003-01-01

    Following the recognition that airborne particulate matter, even at quite modest concentrations, has an adverse effect on human health, there has been an intense research effort to understand the mechanisms and quantify the effects. One feature that has shone through is the important role of ultrafine particles as a contributor to the adverse effects of airborne particles. In this volume, many of the most distinguished researchers in the field provide a state-of-the-art overview of the scientific and medical research on ultrafine particles. Contents: Measurements of Number, Mass and Size Distr

  3. Nanomaterials vs Ambient Ultrafine Particles

    DEFF Research Database (Denmark)

    Stone, Vicki; Miller, Mark R.; Clift, Martin J. D.

    2017-01-01

    BACKGROUND: A rich body of literature exists that has demonstrated adverse human health effects following exposure to ambient air particulate matter (PM), and there is strong support for an important role of ultrafine (nanosized) particles. At present, relatively few human health or epidemiology ...

  4. Surgical smoke and ultrafine particles

    Directory of Open Access Journals (Sweden)

    Nowak Dennis

    2008-12-01

    Full Text Available Abstract Background Electrocautery, laser tissue ablation, and ultrasonic scalpel tissue dissection all generate a 'surgical smoke' containing ultrafine ( Methods To measure the amount of generated particulates in 'surgical smoke' during different surgical procedures and to quantify the particle number concentration for operation room personnel a condensation particle counter (CPC, model 3007, TSI Inc. was applied. Results Electro-cauterization and argon plasma tissue coagulation induced the production of very high number concentration (> 100000 cm-3 of particles in the diameter range of 10 nm to 1 μm. The peak concentration was confined to the immediate local surrounding of the production side. In the presence of a very efficient air conditioning system the increment and decrement of ultrafine particle occurrence was a matter of seconds, with accumulation of lower particle number concentrations in the operation room for only a few minutes. Conclusion Our investigation showed a short term very high exposure to ultrafine particles for surgeons and close assisting operating personnel – alternating with longer periods of low exposure.

  5. Personal exposure to ultrafine particles.

    Science.gov (United States)

    Wallace, Lance; Ott, Wayne

    2011-01-01

    Personal exposure to ultrafine particles (UFP) can occur while people are cooking, driving, smoking, operating small appliances such as hair dryers, or eating out in restaurants. These exposures can often be higher than outdoor concentrations. For 3 years, portable monitors were employed in homes, cars, and restaurants. More than 300 measurement periods in several homes were documented, along with 25 h of driving two cars, and 22 visits to restaurants. Cooking on gas or electric stoves and electric toaster ovens was a major source of UFP, with peak personal exposures often exceeding 100,000 particles/cm³ and estimated emission rates in the neighborhood of 10¹² particles/min. Other common sources of high UFP exposures were cigarettes, a vented gas clothes dryer, an air popcorn popper, candles, an electric mixer, a toaster, a hair dryer, a curling iron, and a steam iron. Relatively low indoor UFP emissions were noted for a fireplace, several space heaters, and a laser printer. Driving resulted in moderate exposures averaging about 30,000 particles/cm³ in each of two cars driven on 17 trips on major highways on the East and West Coasts. Most of the restaurants visited maintained consistently high levels of 50,000-200,000 particles/cm³ for the entire length of the meal. The indoor/outdoor ratios of size-resolved UFP were much lower than for PM₂.₅ or PM₁₀, suggesting that outdoor UFP have difficulty in penetrating a home. This in turn implies that outdoor concentrations of UFP have only a moderate effect on personal exposures if indoor sources are present. A time-weighted scenario suggests that for typical suburban nonsmoker lifestyles, indoor sources provide about 47% and outdoor sources about 36% of total daily UFP exposure and in-vehicle exposures add the remainder (17%). However, the effect of one smoker in the home results in an overwhelming increase in the importance of indoor sources (77% of the total).

  6. Efficiency of cloud condensation nuclei formation from ultrafine particles

    Directory of Open Access Journals (Sweden)

    J. R. Pierce

    2007-01-01

    Full Text Available Atmospheric cloud condensation nuclei (CCN concentrations are a key uncertainty in the assessment of the effect of anthropogenic aerosol on clouds and climate. The ability of new ultrafine particles to grow to become CCN varies throughout the atmosphere and must be understood in order to understand CCN formation. We have developed the Probability of Ultrafine particle Growth (PUG model to answer questions regarding which growth and sink mechanisms control this growth, how the growth varies between different parts of the atmosphere and how uncertainties with respect to the magnitude and size distribution of ultrafine emissions translates into uncertainty in CCN generation. The inputs to the PUG model are the concentrations of condensable gases, the size distribution of ambient aerosol, particle deposition timescales and physical properties of the particles and condensable gases. It was found in most cases that condensation is the dominant growth mechanism and coagulation with larger particles is the dominant sink mechanism for ultrafine particles. In this work we found that the probability of a new ultrafine particle generating a CCN varies from <0.1% to ~90% in different parts of the atmosphere, though in the boundary layer a large fraction of ultrafine particles have a probability between 1% and 40%. Some regions, such as the tropical free troposphere, are areas with high probabilities; however, variability within regions makes it difficult to predict which regions of the atmosphere are most efficient for generating CCN from ultrafine particles. For a given mass of primary ultrafine aerosol, an uncertainty of a factor of two in the modal diameter can lead to an uncertainty in the number of CCN generated as high as a factor for eight. It was found that no single moment of the primary aerosol size distribution, such as total mass or number, is a robust predictor of the number of CCN ultimately generated. Therefore, a complete description of the

  7. Polymer degradation and ultrafine particles - Potential inhalation hazards for astronauts

    Science.gov (United States)

    Ferin, J.; Oberdoerster, G.

    1992-01-01

    To test the hypothesis that exposure to ultrafine particles results in an increased interstiatilization of the particles which is accompanied by an acute pathological inflammation, rats were exposed to titanium dioxide (TiO2) particles by intratracheal instillation and by inhalation. Both acute intratracheal instillation and subchronic inhalation studies on rats show that ultrafine TiO2 particles access the pulmonary interstitium to a larger extent than fine particles and that they elicit an inflammatory response as indicated by PMN increase in lavaged cells. The release of ultrafine particles into the air of an enclosed environment from a thermodegradation event or from other sources is a potential hazard for astronauts. Knowing the mechanisms of action is a prerequisite for technical or medical countermeasures.

  8. [Ultrafine particle number concentration and size distribution of vehicle exhaust ultrafine particles].

    Science.gov (United States)

    Lu, Ye-qiang; Chen, Qiu-fang; Sun, Zai; Cai, Zhi-liang; Yang, Wen-jun

    2014-09-01

    Ultrafine particle (UFP) number concentrations obtained from three different vehicles were measured using fast mobility particle sizer (FMPS) and automobile exhaust gas analyzer. UFP number concentration and size distribution were studied at different idle driving speeds. The results showed that at a low idle speed of 800 rmin-1 , the emission particle number concentration was the lowest and showed a increasing trend with the increase of idle speed. The majority of exhaust particles were in Nuclear mode and Aitken mode. The peak sizes were dominated by 10 nm and 50 nm. Particle number concentration showed a significantly sharp increase during the vehicle acceleration process, and was then kept stable when the speed was stable. In the range of 0. 4 m axial distance from the end of the exhaust pipe, the particle number concentration decayed rapidly after dilution, but it was not obvious in the range of 0. 4-1 m. The number concentration was larger than the background concentration. Concentration of exhaust emissions such as CO, HC and NO showed a reducing trend with the increase of idle speed,which was in contrast to the emission trend of particle number concentration.

  9. Separation of ultrafine particles from class F fly ashes

    Directory of Open Access Journals (Sweden)

    Acar Ilker

    2016-01-01

    Full Text Available In this study, ultrafine particles were recovered from Çatalağzı (CFA and Sugözü (SFA thermal power plant fly ashes using a specific hydraulic classification technology. Since fly ashes have a high tendency to be flocculated in water, settling experiments were first designed to determine the more effective dispersant and the optimum dosage. Two different types of the superplasticizers (SP polymers based on sulphonate (NSF, Disal and carboxylate (Glenium 7500 were used as the dispersing agents in these settling experiments. Hydraulic classification experiments were then conducted to separate ultrafine fractions from the fly ash samples on the basis of the settling experiments. According to the settling experiments, better results were achieved with the use of Disal for both CFA and SFA. The classification experiments showed that the overflow products with average particle sizes of 5.2 μm for CFA and 4.4 μm for SFA were separated from the respective as-received samples with acceptable yields and high enough recoveries of -5 μm (ultrafine particles. Overall results pointed out that the hydraulic classification technology used provided promising results in the ultrafine particle separations from the fly ash samples.

  10. Outdoor ultrafine particle concentrations in front of fast food restaurants

    NARCIS (Netherlands)

    Vert, Cristina; Meliefste, Kees; Hoek, Gerard

    2016-01-01

    Ultrafine particles (UFPs) have been associated with negative effects on human health. Emissions from motor vehicles are the principal source of UFPs in urban air. A study in Vancouver suggested that UFP concentrations were related to density of fast food restaurants near the monitoring sites. A

  11. Sources of ultrafine particles in the Eastern United States

    Science.gov (United States)

    Posner, Laura N.; Pandis, Spyros N.

    2015-06-01

    Source contributions to ultrafine particle number concentrations for a summertime period in the Eastern U.S. are investigated using the chemical transport model PMCAMx-UF. New source-resolved number emissions inventories are developed for biomass burning, dust, gasoline automobiles, industrial sources, non-road and on-road diesel. According to the inventory for this summertime period in the Eastern U.S., gasoline automobiles are responsible for 40% of the ultrafine particle number emissions, followed by industrial sources (33%), non-road diesel (16%), on-road diesel (10%), and 1% from biomass burning and dust. With these emissions as input, the chemical transport model PMCAMx-UF reproduces observed ultrafine particle number concentrations (N3-100) in Pittsburgh with an error of 12%. For this summertime period in the Eastern U.S., nucleation is predicted to be the source of more than 90% of the total particle number concentrations. The source contributions to primary particle number concentrations are on average similar to those of their source emissions contributions: gasoline is predicted to contribute 36% of the total particle number concentrations, followed by industrial sources (31%), non-road diesel (18%), on-road diesel (10%), biomass burning (1%), and long-range transport (4%). For this summertime period in Pittsburgh, number source apportionment predictions for particles larger than 3 nm in diameter (traffic 65%, other combustion sources 35%) are consistent with measurement-based source apportionment (traffic 60%, combustion sources 40%).

  12. Physicochemical characterization of Baizhi particles by ultrafine pulverization

    Science.gov (United States)

    Yang, Lian-Wei; Sun, Peng; Gai, Guo-Sheng; Yang, Yu-Fen; Wang, Yu-Rong

    2011-04-01

    Baizhi, as a medicinal plant, has been demonstrated to be useful for the treatment of aches and pains in China. The physicochemical characterization of Baizhi particles is greatly influenced by ultrafine pulverization. To study the physicochemical characterization of Baizhi, the raw plant material of Baizhi was ground to 6 μm particles by a high speed centrifugal sheering (HSCS) pulverizer. The micron particles were characterized by optical microscopy and scanning electron microscopy (SEM). Imperatorin is one of the active ingredients of Baizhi, and its extraction yield is determined to evaluate the chemical characterization of Baizhi powder. Imperatorin was analyzed by high performance liquid chromatography (HPLC). The results show that after ultrafine pulverization, the plant cell walls are broken into pieces and the extraction yield of imperatorin is increased by 11.93% compared with the normal particles.

  13. Ultrafine particles in concrete: Influence of ultrafine particles on concrete properties and application to concrete mix design

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, Carsten

    2010-07-01

    In this work, the influence of ultrafine particles on concrete properties was investigated. In the context of this work, ultrafine particles (reactive and inert materials) are particles finer than cement. Due to the development of effective superplasticizers, the incorporation of ultrafine particles in concrete is nowadays possible. Different minerals, usually considered inert, were tested. These minerals were also used in combination with reactive silica fume. The modified Andreassen model was used to optimise the particle size distribution and thus the packing density of the complete mix composition. Heat of hydration, compressive strength, shrinkage, frost resistance and the microstructure were investigated.The influence of different ultrafine inert materials on the cement hydration was investigated. The results show that most of the minerals have an accelerating effect. They provide nucleation sites for hydration products and contribute in that way to a faster dissolution of cement grains. Minerals containing calcium were found to influence the early stage of hydration as well. These minerals shortened the dormant period of the cement hydration, the effect is known from limestone filler in self-compacting concrete. In a first test series on concrete, different ultrafine inert particles were used to replace cement. That was done in several ways; with constant water content or constant w/c. The results from this test series show that the best effect is achieved when cement is replaced by suitable ultrafines while the w/c is kept constant. In doing so, the compressive strength can be increased and shrinkage can be reduced. The microstructure is improved and becomes denser with improved packing at microlevel. Efficiency factors (k values) for the ultrafine inert materials were calculated from the compressive strength results. The k values are strongly dependent on the mode of cement replacement, fineness and type of the replacement material and curing time. Drying

  14. Unipolar and bipolar diffusion charging of ultrafine particles

    International Nuclear Information System (INIS)

    Adachi, Motoaki; Okuyama, Kikuo; Kousaka, Yasuo.

    1985-01-01

    Unipolar and bipolar diffusion charging of monodisperse ultrafine particles of 4 - 100 nm in diameter has been studied experimentally and theoretically. The particles were charged by unipolar and bipolar ions generated by α-ray irradiation and the charge distribution of particles was directly observed in the electric field after the growth of them by condensation of di-butyl phthalate vapor. In both cases of unipolar and bipolar charging, the experimental results have been found in good agreement with the solution of basic equations where Fuchs' formula is used as the combination probability of an ion with a particle. (author)

  15. Volatility and mixing states of ultrafine particles from biomass burning

    International Nuclear Information System (INIS)

    Maruf Hossain, A.M.M.; Park, Seungho; Kim, Jae-Seok; Park, Kihong

    2012-01-01

    Highlights: ► Size distribution, volatility, and mixing states of ultrafine particles emitted from rice straw, oak, and pine burning under different burning conditions were investigated. ► Smoldering combustion emitted larger mode particles in higher numbers than smaller mode particles, while the converse was true for flaming combustion. ► While the flaming combustion and open burning results imply there is internal mixing of OC and BC, smoldering combustion in rice straw produced ultrafine particles devoid of BC. ► Mixing state of ultrafine particles from biomass burning can alter the single scattering albedo, and might even change the sign of radiative forcing. - Abstract: Fine and ultrafine carbonaceous aerosols produced from burning biomasses hold enormous importance in terms of assessing radiation balance and public health hazards. As such, volatility and mixing states of size-selected ultrafine particles (UFP) emitted from rice straw, oak, and pine burning were investigated by using volatility tandem differential mobility analyzer (VTDMA) technique in this study. Rice straw combustion produced unimodal size distributions of emitted aerosols, while bimodal size distributions from combustions of oak (hardwood) and pine (softwood) were obtained. A nearness of flue gas temperatures and a lower CO ratio of flaming combustion (FC) to smoldering combustion (SC) were characteristic differences found between softwood and hardwood. SC emitted larger mode particles in higher numbers than smaller mode particles, while the converse was true for FC. Rice straw open burning UFPs exhibited a volatilization behavior similar to that between FC and SC. In addition, internal mixing states were observed for size-selected UFPs in all biomasses for all combustion conditions, while external mixing states were only observed for rice straw combustion. Results for FC and open burning suggested there was an internal mixing of volatile organic carbon (OC) and non-volatile core (e

  16. Characterization of ultrafine and fine particles from CHP Plants

    Energy Technology Data Exchange (ETDEWEB)

    2009-08-15

    Samples of particles collected at CHP plants in the project 'Survey of emissions from CHP Plants' have been analysed in this project to give information on the morphology and chemical composition of individual particle size classes. The objective of this project was to characterize ultrafine and fine particles emitted to the atmosphere from Danish CHP plants. Nine CHP plants were selected in the Emission Survey Project as being representative for the different types of CHP plants operating in Denmark: 1) Three Waste-to Energy (WTE) plants. 2) Three biomass fired (BM) plants (two straw fired, one wood/saw dust fired). 3) Two gas fired (GF) plants (one natural gas, one landfill gas fired). 4) One gasoil (GO) fired plant. At the WTE and BM plants, various types of emission control systems implemented. The results from these plants represent the composition and size distribution of combustion particles that are emitted from the plants emission control systems. The measured emissions of particles from the waste-to-energy plants WTE1-3 are generally very low. The number and mass concentrations of ultrafine particles (PM{sub 0.1}) were particularly low in the flue gas from WTE2 and WTE3, where bag filters are used for the reduction of particle emissions. The EDX analysis of particles from the WTE plants indicates that the PM{sub 0.1} that penetrates the ECS at WTE can contain high fractions of metals such as Fe, Mn and Cu. The SEM analysis of particles from WTE1-3 showed that the particles were generally porous and irregular in shape. The concentrations of particles in the flue gas from the biomass plants were generally higher than found for the WTE plants. The time series results showed that periodical, high concentration peaks of PM emissions occur from BM1 and BM2. The chemical composition of the particles emitted from the three biomass plants is generally dominated by C, O and S, and to some extend also Fe and Si. A high amount of Cu was found in selected

  17. Challenges and Approaches for Developing Ultrafine Particle Emission Inventories for Motor Vehicle and Bus Fleets

    Directory of Open Access Journals (Sweden)

    Diane U. Keogh

    2011-03-01

    Full Text Available Motor vehicles in urban areas are the main source of ultrafine particles (diameters < 0.1 µm. Ultrafine particles are generally measured in terms of particle number because they have little mass and are prolific in terms of their numbers. These sized particles are of particular interest because of their ability to enter deep into the human respiratory system and contribute to negative health effects. Currently ultrafine particles are neither regularly monitored nor regulated by ambient air quality standards. Motor vehicle and bus fleet inventories, epidemiological studies and studies of the chemical composition of ultrafine particles are urgently needed to inform scientific debate and guide development of air quality standards and regulation to control this important pollution source. This article discusses some of the many challenges associated with modelling and quantifying ultrafine particle concentrations and emission rates for developing inventories and microscale modelling of motor vehicles and buses, including the challenge of understanding and quantifying secondary particle formation. Recommendations are made concerning the application of particle emission factors in developing ultrafine particle inventories for motor vehicle fleets. The article presents a précis of the first published inventory of ultrafine particles (particle number developed for the urban South-East Queensland motor vehicle and bus fleet in Australia, and comments on the applicability of the comprehensive set of average particle emission factors used in this inventory, for developing ultrafine particle (particle number and particle mass inventories in other developed countries.

  18. Deposition of fine and ultrafine particles on indoor surface materials

    DEFF Research Database (Denmark)

    Afshari, Alireza; Reinhold, Claus

    2008-01-01

    -scale test chamber. Experiments took place in a 32 m3 chamber with walls and ceiling made of glass. Prior to each experiment the chamber was flushed with outdoor air to reach an initial particle concentration typical of indoor air in buildings with natural ventilation. The decay of particle concentrations...... The aim of this study was the experimental determination of particle deposition for both different particle size fractions and different indoor surface materials. The selected surface materials were glass, gypsum board, carpet, and curtain. These materials were tested vertically in a full...... was monitored. Seven particle size fractions were studied. These comprised ultrafine and fine particles. Deposition was higher on carpet and curtain than on glass and gypsum board. Particles ranging from 0.3 to 0.5 µm had the lowest deposition. This fraction also has the highest penetration and its indoor...

  19. Removal of ultrafine particles from indoor environment

    DEFF Research Database (Denmark)

    Ardkapan, Siamak Rahimi

    in a CFD simulation or if particles are considered of one single size, a deviation from reality may occur. It was concluded that an ozone generating air cleaning technology may increase the level of ozone to a level that exceeds the allowed level of 120 μgm-3 according to Air Quality Guidelines for Europe...... effect on the removal effectiveness in a room with a displacement airflow pattern. According to the simulation study of particle dispersion in a room, it was concluded that the location of a particle source has impact on the UFP concentration profile in the room....

  20. Dewatering behaviour of ultrafine hard coal particles

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, D.; Alizadeh, A.; Simonis, W.

    1986-03-01

    With decreasing particle diameter distribution the dewatering behaviour of coal gets increasingly complicated. A correlation between final moisture and content of particles below 25..mu..m in the course of centrifuging can be verified. This behaviour of the particles below 25..mu..m can be explained by the great specific surface, on the one hand, and by the distribution of the surface charge density, on the other hand. The charge density depends on the type of coal, on the minerals content and their make-up, as well as on the characteristics of the surrounding medium. The surface charge can be measured indirectly. Varying electrophoretic mobilities of the particles are observed in dependence on the type of raw material. In the neutral pH-range, minerals have a negative surface charge, while coal has a positive one. By way of adding reagents it is possible to invert the negative charges with complicated dewatering characteristics into positive charges. A similar influence will be exerted by changing the pH-value. 6 references.

  1. Exposure to airborne ultrafine particles from cooking in Portuguese homes.

    Science.gov (United States)

    Bordado, J C; Gomes, J F; Albuquerque, P C

    2012-10-01

    Cooking was found to be a main source of submicrometer and ultrafine aerosols from gas combustion in stoves. Therefore, this study consisted of the determination of the alveolar deposited surface area due to aerosols resulting from common domestic cooking activities (boiling fish, vegetables, or pasta, and frying hamburgers and eggs). The concentration of ultrafine particles during the cooking events significantly increased from a baseline of 42.7 microm2/cm3 (increased to 72.9 microm2/cm3 due to gas burning) to a maximum of 890.3 microm2/cm3 measured during fish boiling in water and a maximum of 4500 microm2/cm3 during meat frying. This clearly shows that a domestic activity such as cooking can lead to exposures as high as those of occupational exposure activities. The approach of this study considers the determination of alveolar deposited surface area of aerosols generated from cooking activities, namely, typical Portuguese dishes. This type of measurement has not been done so far, in spite of the recognition that cooking activity is a main source of submicrometer and ultrafine aerosols. The results have shown that the levels of generated aerosols surpass the outdoor concentrations in a major European town, which calls for further determinations, contributing to a better assessment of exposure of individuals to domestic activities such as this one.

  2. Exposure to inhalable, respirable, and ultrafine particles in welding fume.

    Science.gov (United States)

    Lehnert, Martin; Pesch, Beate; Lotz, Anne; Pelzer, Johannes; Kendzia, Benjamin; Gawrych, Katarzyna; Heinze, Evelyn; Van Gelder, Rainer; Punkenburg, Ewald; Weiss, Tobias; Mattenklott, Markus; Hahn, Jens-Uwe; Möhlmann, Carsten; Berges, Markus; Hartwig, Andrea; Brüning, Thomas

    2012-07-01

    This investigation aims to explore determinants of exposure to particle size-specific welding fume. Area sampling of ultrafine particles (UFP) was performed at 33 worksites in parallel with the collection of respirable particles. Personal sampling of respirable and inhalable particles was carried out in the breathing zone of 241 welders. Median mass concentrations were 2.48 mg m(-3) for inhalable and 1.29 mg m(-3) for respirable particles when excluding 26 users of powered air-purifying respirators (PAPRs). Mass concentrations were highest when flux-cored arc welding (FCAW) with gas was applied (median of inhalable particles: 11.6 mg m(-3)). Measurements of particles were frequently below the limit of detection (LOD), especially inside PAPRs or during tungsten inert gas welding (TIG). However, TIG generated a high number of small particles, including UFP. We imputed measurements welding fume. Concentrations were mainly predicted by the welding process and were significantly higher when local exhaust ventilation (LEV) was inefficient or when welding was performed in confined spaces. Substitution of high-emission techniques like FCAW, efficient LEV, and using PAPRs where applicable can reduce exposure to welding fume. However, harmonizing the different exposure metrics for UFP (as particle counts) and for the respirable or inhalable fraction of the welding fume (expressed as their mass) remains challenging.

  3. Personal exposure to ultrafine particles and oxidative DNA damage

    DEFF Research Database (Denmark)

    Vinzents, Peter S; Møller, Peter; Sørensen, Mette

    2005-01-01

    Exposure to ultrafine particles (UFPs) from vehicle exhaust has been related to risk of cardiovascular and pulmonary disease and cancer, even though exposure assessment is difficult. We studied personal exposure in terms of number concentrations of UFPs in the breathing zone, using portable instr......, particularly during bicycling in traffic. The results indicate that biologic effects of UFPs occur at modest exposure, such as that occurring in traffic, which supports the relationship of UFPs and the adverse health effects of air pollution.......Exposure to ultrafine particles (UFPs) from vehicle exhaust has been related to risk of cardiovascular and pulmonary disease and cancer, even though exposure assessment is difficult. We studied personal exposure in terms of number concentrations of UFPs in the breathing zone, using portable...... instruments in six 18-hr periods in 15 healthy nonsmoking subjects. Exposure contrasts of outdoor pollution were achieved by bicycling in traffic for 5 days and in the laboratory for 1 day. Oxidative DNA damage was assessed as strand breaks and oxidized purines in mononuclear cells isolated from venous blood...

  4. Ultrafine particles over Eastern Australia: an airborne survey

    Directory of Open Access Journals (Sweden)

    Wolfgang Junkermann

    2015-04-01

    Full Text Available Ultrafine particles (UFP in the atmosphere may have significant impacts on the regional water and radiation budgets through secondary effects on cloud microphysics. Yet, as these particles are invisible for current remote sensing techniques, knowledge about their three-dimensional distribution, source strengths and budgets is limited. Building on a 40-yr-old Australia-wide airborne survey which provides a reference case study of aerosol sources and budgets, this study presents results from a new airborne survey over Eastern Australia, northern New South Wales and Queensland. Observations identified apparent changes in the number and distribution of major anthropogenic aerosol sources since the early 1970s, which might relate to the simultaneously observed changes in rainfall patterns over eastern Queensland. Coal-fired power stations in the inland areas between Brisbane and Rockhampton were clearly identified as the major sources for ultrafine particulate matter. Sugar mills, smelters and shipping along the coast close to the Ports of Townsville and Rockhampton were comparable minor sources. Airborne Lagrangian plume studies were applied to investigate source strength and ageing properties within power station plumes. Significant changes observed, compared to the measurements in the 1970s, included a significant increase in the number concentration of UFP related to coal-fired power station emissions in the sparsely populated Queensland hinterland coincident with the area with the most pronounced reduction in rainfall.

  5. Method for fluidizing and coating ultrafine particles, device for fluidizing and coating ultrafine particles

    Science.gov (United States)

    Li, Jie; Liu, Yung Y

    2015-01-20

    The invention provides a method for dispersing particles within a reaction field, the method comprising confining the particles to the reaction field using a standing wave. The invention also provides a system for coating particles, the system comprising a reaction zone; a means for producing fluidized particles within the reaction zone; a fluid to produce a standing wave within the reaction zone; and a means for introducing coating moieties to the reaction zone. The invention also provides a method for coating particles, the method comprising fluidizing the particles, subjecting the particles to a standing wave; and contacting the subjected particles with a coating moiety.

  6. Vascular effects of ultrafine particles in persons with type 2 diabetes

    Science.gov (United States)

    BACKGROUND: Diabetes confers an increased risk for cardiovascular effects of airborne particles. OBJECTIVE: We hypothesized that inhalation of elemental carbon ultrafine particles (UFP) would activate blood platelets and vascular endothelium in people with type 2 diabetes. ...

  7. Filtration efficiency of an electrostatic fibrous filter: Studying filtration dependency on ultrafine particle exposure and composition

    DEFF Research Database (Denmark)

    Ardkapan, Siamak Rahimi; Johnson, Matthew S.; Yazdi, Sadegh

    2014-01-01

    The objective of the present study is to investigate the relationship between ultrafine particle concentrations and removal efficiencies for an electrostatic fibrous filter in a laboratory environment. Electrostatic fibrous filters capture particles efficiently, with a low pressure drop. Therefor...

  8. Substantial convection and precipitation enhancements by ultrafine aerosol particles

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Jiwen; Rosenfeld, Daniel; Zhang, Yuwei; Giangrande, Scott E.; Li, Zhanqing; Machado, Luiz A. T.; Martin, Scot T.; Yang, Yan; Wang, Jian; Artaxo, Paulo; Barbosa, Henrique M. J.; Braga, Ramon C.; Comstock, Jennifer M.; Feng, Zhe; Gao, Wenhua; Gomes, Helber B.; Mei, Fan; Pöhlker, Christopher; Pöhlker, Mira L.; Pöschl, Ulrich; de Souza, Rodrigo A. F.

    2018-01-25

    Aerosol-cloud interaction remains the largest uncertainty in climate projections. Ultrafine aerosol particles (UAP; size <50nm) are considered too small to serve as cloud condensation nuclei conventionally. However, this study provides observational evidence to accompany insights from numerical simulations to support that deep convective clouds (DCCs) over Amazon have strong capability of nucleating UAP from an urban source and forming greater numbers of droplets, because fast drop coalescence in these DCCs reduces drop surface area available for condensation, leading to high vapor supersaturation. The additional droplets subsequently decrease supersaturation and release more condensational latent heating, a dominant contributor to convection intensification, whereas enhanced latent heat from ice-related processes plays a secondary role. Therefore, the addition of anthropogenic UAP may play a much greater role in modulating clouds than previously believed over the Amazon region and possibly in other relatively pristine regions such as maritime and forest locations.

  9. POTENTIAL PATHOPHYSIOLOGICAL MECHANISMS OF ULTRAFINE PARTICLE TOXIC EFFECTS IN HUMANS

    Directory of Open Access Journals (Sweden)

    JASMINA JOVIĆ-STOŠIĆ

    2008-03-01

    Full Text Available Epidemiological and clinical studies suggested the association of the particulate matter ambient air pollution and the increased morbidity and mortality, mainly from respiratory and cardiovascular diseases. The size of particles has great influence on their toxicity, because it determines the site in the respiratory tract where they deposit. The most well established theory explaining the mechanisms behind the increased toxicity of ultrafine particles (UFP, < 0.1 µm is that it has to do with the increased surface area and/or the combination with the increased number of particles. Biological effects of UFP are also determined by their shape and chemical composition, so it is not possible to estimate their toxicity in a general way. General hypothesis suggested that exposure to inhaled particles induces pulmonary alveolar inflammation as a basic pathophysiological event, triggering release of various proinflammatory cytokines. Chronic inflammation is a very important underlying mechanism in the genesis of atherosclerosis and cardiovascular diseases. UFP can freely move through the circulation, but their effects on the secondary organs are not known yet, so more studies on recognizing toxicological endpoints of UFP are needed. Determination of UFP toxicity and the estimation of their internal and biologically active dose are necessary for the evidence based conclusions connecting air pollution by UFP and human diseases.

  10. Comparison of deposited surface area of airborne ultrafine particles generated from two welding processes.

    Science.gov (United States)

    Gomes, J F; Albuquerque, P C; Miranda, Rosa M; Santos, Telmo G; Vieira, M T

    2012-09-01

    This article describes work performed on the assessment of the levels of airborne ultrafine particles emitted in two welding processes metal-active gas (MAG) of carbon steel and friction-stir welding (FSW) of aluminium in terms of deposited area in alveolar tract of the lung using a nanoparticle surface area monitor analyser. The obtained results showed the dependence from process parameters on emitted ultrafine particles and clearly demonstrated the presence of ultrafine particles, when compared with background levels. The obtained results showed that the process that results on the lower levels of alveolar-deposited surface area is FSW, unlike MAG. Nevertheless, all the tested processes resulted in important doses of ultrafine particles that are to be deposited in the human lung of exposed workers.

  11. Expert elicitation on ultrafine particles: likelihood of health effects and causal pathways.

    NARCIS (Netherlands)

    Knol, A.B.; de Hartog, J.J.|info:eu-repo/dai/nl/288354850; Boogaard, H.|info:eu-repo/dai/nl/314406522; Slottje, P.|info:eu-repo/dai/nl/299345351; van der Sluijs, J.P.|info:eu-repo/dai/nl/073427489; Lebret, E.|info:eu-repo/dai/nl/071318917; Cassee, F.R.|info:eu-repo/dai/nl/143038990; Wardekker, J.A.|info:eu-repo/dai/nl/306644398; Ayres, J.G.; Borm, P.; Brunekreef, B.|info:eu-repo/dai/nl/067548180; Donaldson, K.; Forastiere, F.; Holgate, S.T.; Kreyling, W.; Nemery, B.; Pekkanen, J.; Stone, V.; Wichmann, H.E.; Hoek, G.|info:eu-repo/dai/nl/069553475

    2009-01-01

    ABSTRACT: BACKGROUND: Exposure to fine ambient particulate matter (PM) has consistently been associated with increased morbidity and mortality. The relationship between exposure to ultrafine particles (UFP) and health effects is less firmly established. If UFP cause health effects independently from

  12. Outdoor ultrafine particle concentrations in front of fast food restaurants.

    Science.gov (United States)

    Vert, Cristina; Meliefste, Kees; Hoek, Gerard

    2016-01-01

    Ultrafine particles (UFPs) have been associated with negative effects on human health. Emissions from motor vehicles are the principal source of UFPs in urban air. A study in Vancouver suggested that UFP concentrations were related to density of fast food restaurants near the monitoring sites. A previous monitoring campaign could not separate the contribution of restaurants from road traffic. The main goal of this study has been the quantification of fast food restaurants' contribution to outdoor UFP concentrations. A portable particle number counter (DiscMini) has been used to carry out mobile monitoring in a largely pedestrianized area in the city center of Utrecht. A fixed route passing 17 fast food restaurants was followed on 8 days. UFP concentrations in front of the restaurants were 1.61 times higher than in a nearby square without any local sources used as control area and 1.22 times higher compared with all measurements conducted in between the restaurants. Adjustment for other sources such as passing mopeds, smokers or candles did not explain the increase. In conclusion, fast food restaurants result in significant increases in outdoor UFP concentrations in front of the restaurant.

  13. Seasonal variation and volatility of ultra-fine particles in coastal Antarctic troposphere

    Directory of Open Access Journals (Sweden)

    Keiichiro Hara

    2010-12-01

    Full Text Available The Size distribution and volatility of ultrafine aerosol particles were measured at Syowa Station during the 46-47 Japanese Antarctic Research Expeditions. During the summer, most of the ultrafine particles were volatile particles, which were composed of H_2SO_4, CH_3SO_3H and sulfates bi-sulfates. The abundance of non-volatile particles was ~ 20% during the summer, increasing to>90% in winter-spring. Non-volatile particles in winter were dominantly sea-salt particles. Some ultrafine sea-salt particles might be released from sea-ice. When air mass was transported from the free troposphere over the Antarctic continent, the abundance of non-volatile particles dropped to<30% even in winter.

  14. Workplace Measurements of Ultrafine Particles-A Literature Review.

    Science.gov (United States)

    Viitanen, Anna-Kaisa; Uuksulainen, Sanni; Koivisto, Antti J; Hämeri, Kaarle; Kauppinen, Timo

    2017-08-01

    Workers are exposed to ultrafine particles (UFP) in a number of occupations. In order to summarize the current knowledge regarding occupational exposure to UFP (excluding engineered nanoparticles), we gathered information on UFP concentrations from published research articles. The aim of our study was to create a basis for future epidemiological studies that treat UFP as an exposure factor. The literature search found 72 publications regarding UFP measurements in work environments. These articles covered 314 measurement results and tabled concentrations. Mean concentrations were compared to typical urban UFP concentration level, which was considered non-occupational background concentration. Mean concentrations higher than the typical urban UFP concentration were reported in 240 workplace measurements. The results showed that workers' exposure to UFP may be significantly higher than their non-occupational exposure to background concentration alone. Mean concentrations of over 100 times the typical urban UFP concentration were reported in welding and metal industry. However, according to the results of the review, measurements of the UFP in work environments are, to date, too limited and reported too heterogeneous to allow us to draw general conclusions about workers' exposure. Harmonization of measurement strategies is essential if we are to generate more reliable and comparable data in the future. © The Author 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

  15. Ultrafine particle air pollution inside diesel-propelled passenger trains.

    Science.gov (United States)

    Abramesko, Victoria; Tartakovsky, Leonid

    2017-07-01

    Locomotives with diesel engines are used worldwide and are an important source of air pollution. Pollutant emissions by locomotive engines affect the air quality inside passenger trains. This study is aimed at investigating ultrafine particle (UFP) air pollution inside passenger trains and providing a basis for assessing passenger exposure to this pollutant. The concentrations of UFPs inside the carriages of push-pull trains are dramatically higher when the train operates in pull mode. This clearly shows that locomotive engine emissions are a dominant factor in train passengers' exposure to UFPs. The highest levels of UFP air pollution are observed inside the carriages of pull trains close to the locomotive. In push mode, the UFP number concentrations were lower by factors of 2.6-43 (depending on the carriage type) compared to pull mode. The UFP concentrations are substantially lower in diesel multiple-unit trains than in trains operating in pull mode. A significant influence of the train movement regime on the UFP NC inside a carriage is observed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Release of ultrafine particles from three simulated building processes

    International Nuclear Information System (INIS)

    Kumar, Prashant; Mulheron, Mike; Som, Claudia

    2012-01-01

    Building activities are recognised to produce coarse particulate matter but less is known about the release of airborne ultrafine particles (UFPs; those below 100 nm in diameter). For the first time, this study has investigated the release of particles in the 5–560 nm range from three simulated building activities: the crushing of concrete cubes, the demolition of old concrete slabs, and the recycling of concrete debris. A fast response differential mobility spectrometer (Cambustion DMS50) was used to measure particle number concentrations (PNC) and size distributions (PNDs) at a sampling frequency of 10 Hz in a confined laboratory room providing controlled environment and near–steady background PNCs. The sampling point was intentionally kept close to the test samples so that the release of new UFPs during these simulated processes can be quantified. Tri–modal particle size distributions were recorded for all cases, demonstrating different peak diameters in fresh nuclei ( 4 cm −3 . These background modal peaks shifted towards the larger sizes during the work periods (i.e. actual experiments) and the total PNCs increased between 2 and 17 times over the background PNCs for different activities. After adjusting for background concentrations, the net release of PNCs during cube crushing, slab demolition, and ‘dry’ and ‘wet’ recycling events were measured as ∼0.77, 19.1, 22.7 and 1.76 (×10 4 ) cm −3 , respectively. The PNDs were converted into particle mass concentrations (PMCs). While majority of new PNC release was below 100 nm (i.e. UFPs), the bulk of new PMC emissions were constituted by the particles over 100 nm; ∼95, 79, 73 and 90% of total PNCs, and ∼71, 92, 93 and 91% of total PMCs, for cube crushing, slab demolition, dry recycling and wet recycling, respectively. The results of this study firmly elucidate the release of UFPs and raise a need for further detailed studies and designing health and safety related exposure guidelines for

  17. ULTRAFINE PARTICLE DEPOSITION IN HEALTHY SUBJECTS VS. PATIENTS WTH COPD

    Science.gov (United States)

    Individuals affected with chronic obstructive pulmonary disease (COPD) have increased susceptibility to adverse health effects from exposure to particulate air pollution. The dosimetry of ultrafine aerosols (diameter # 0.1 :m) is not well characterized in the healthy or diseas...

  18. Formation and evolution of ultrafine particles produced by radiolysis and photolysis

    International Nuclear Information System (INIS)

    Madelaine, G.J.; Perrin, M.L.; Renoux, A.

    1980-01-01

    Results are presented, concerning the formation, the size distribution, and the behavior of ultrafine particles produced by alpha disintegration of actinium and uv irradiation in filtered and natural atmospheric air. The characterization of these particles is obtained by electrical aerosol analyzer and diffusion battery method. Measurements are made in the range between 0.003 and 0.5 micrometer. Some qualitative indications are obtained on the different mechanisms which govern the evolution of ultrafine particles in the atmosphere (nucleation, coagulation, and condensation). It is now well established that the photo-oxydation of SO 2 in the atmosphere leads to the production of sulphuric acid and of sulphate, which are usually found in the form of submicronic particles. This paper concerns the evolution of ultrafine particles generated in the presence of a preexisting aerosol. They are either instantaneously produced by the alpha disintegrations of actinium 219 or continuously produced by the transformation of SO 2 under uv irradiation

  19. Ultrafine particle emissions from modern Gasoline and Diesel vehicles: An electron microscopic perspective.

    Science.gov (United States)

    Liati, Anthi; Schreiber, Daniel; Arroyo Rojas Dasilva, Yadira; Dimopoulos Eggenschwiler, Panayotis

    2018-08-01

    Ultrafine (electron microscopy (TEM) is applied to obtain a concrete picture on the nature, morphology and chemical composition of non-volatile ultrafine particles in the exhaust of state-of-the-art, Euro 6b, Gasoline and Diesel vehicles. The particles were collected directly on TEM grids, at the tailpipe, downstream of the after-treatment system, during the entire duration of typical driving cycles on the chassis dynamometer. Based on TEM imaging coupled with Energy Dispersive X-ray (EDX) analysis, numerous ultrafine particles could be identified, imaged and analyzed chemically. Particles vehicles and driving cycles. The present TEM study gives information also on the imaging and chemical composition of the solid fraction of the unregulated sub-23 nm size category particles. Copyright © 2018 Elsevier Ltd. All rights reserved.

  20. A mechanism for the production of ultrafine particles from concrete fracture.

    Science.gov (United States)

    Jabbour, Nassib; Rohan Jayaratne, E; Johnson, Graham R; Alroe, Joel; Uhde, Erik; Salthammer, Tunga; Cravigan, Luke; Faghihi, Ehsan Majd; Kumar, Prashant; Morawska, Lidia

    2017-03-01

    While the crushing of concrete gives rise to large quantities of coarse dust, it is not widely recognized that this process also emits significant quantities of ultrafine particles. These particles impact not just the environments within construction activities but those in entire urban areas. The origin of these ultrafine particles is uncertain, as existing theories do not support their production by mechanical processes. We propose a hypothesis for this observation based on the volatilisation of materials at the concrete fracture interface. The results from this study confirm that mechanical methods can produce ultrafine particles (UFP) from concrete, and that the particles are volatile. The ultrafine mode was only observed during concrete fracture, producing particle size distributions with average count median diameters of 27, 39 and 49 nm for the three tested concrete samples. Further volatility measurements found that the particles were highly volatile, showing between 60 and 95% reduction in the volume fraction remaining by 125 °C. An analysis of the volatile fraction remaining found that different volatile material is responsible for the production of particles between the samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Size-dependent proinflammatory effects of ultrafine polystyrene particles: a role for surface area and oxidative stress in the enhanced activity of ultrafines.

    Science.gov (United States)

    Brown, D M; Wilson, M R; MacNee, W; Stone, V; Donaldson, K

    2001-09-15

    Studies into the effects of ultrafine particles in the lung have shown adverse effects considered to be due in part to the particle size. Air pollution particles (PM(10)) are associated with exacerbations of respiratory disease and deaths from cardiovascular causes in epidemiological studies and the ultrafine fraction of PM(10) has been hypothesized to play an important role. The aim of the present study was to investigate proinflammatory responses to various sizes of polystyrene particles as a simple model of particles of varying size including ultrafine. In the animal model, we demonstrated that there was a significantly greater neutrophil influx into the rat lung after instillation of 64-nm polystyrene particles compared with 202- and 535-nm particles and this was mirrored in other parameters of lung inflammation, such as increased protein and lactate dehydrogenase in bronchoalveolar lavage. When surface area instilled was plotted against inflammation, these two variables were directly proportional and the line passed through zero. This suggests that surface area drives inflammation in the short term and that ultrafine particles cause a greater inflammatory response because of the greater surface area they possess. In vitro, we measured the changes in intracellular calcium concentration in mono mac 6 cells in view of the potential role of calcium as a signaling molecule. Calcium changes after particle exposure may be important in leading to proinflammatory gene expression such as chemokines. We demonstrated that only ultrafine polystyrene particles induced a significant increase in cytosolic calcium ion concentration. Experiments using dichlorofluorescin diacetate demonstrated greater oxidant activity of the ultrafine particles, which may explain their activity in these assays. There were significant increases in IL-8 gene expression in A549 epithelial cells after treatment with the ultrafine particles but not particles of other sizes. These findings suggest

  2. Ultrafine particle emission characteristics of diesel engine by on-board and test bench measurement.

    Science.gov (United States)

    Huang, Cheng; Lou, Diming; Hu, Zhiyuan; Tan, Piqiang; Yao, Di; Hu, Wei; Li, Peng; Ren, Jin; Chen, Changhong

    2012-01-01

    This study investigated the emission characteristics of ultrafine particles based on test bench and on-board measurements. The bench test results showed the ultrafine particle number concentration of the diesel engine to be in the range of (0.56-8.35) x 10(8) cm(-3). The on-board measurement results illustrated that the ultrafine particles were strongly correlated with changes in real-world driving cycles. The particle number concentration was down to 2.0 x 10(6) cm(-3) and 2.7 x 10(7) cm(-3) under decelerating and idling operations and as high as 5.0 x 10(8) cm(-3) under accelerating operation. It was also indicated that the particle number measured by the two methods increased with the growth of engine load at each engine speed in both cases. The particle number presented a "U" shaped distribution with changing speed at high engine load conditions, which implies that the particle number will reach its lowest level at medium engine speeds. The particle sizes of both measurements showed single mode distributions. The peak of particle size was located at about 50-80 nm in the accumulation mode particle range. Nucleation mode particles will significantly increase at low engine load operations like idling and decelerating caused by the high concentration of unburned organic compounds.

  3. Combustion of PTFE: The effects of gravity on ultrafine particle generation

    Science.gov (United States)

    McKinnon, Thomas; Todd, Paul; Oberdorster, Gunter

    1996-01-01

    The objective of this project is to obtain an understanding of the effect of gravity on the toxicity of ultrafine particle and gas phase materials produced when fluorocarbon polymers are thermally degraded or burned. The motivation for the project is to provide a basic technical foundation on which policies for spacecraft health and safety with regard to fire and polymers can be formulated.

  4. Ultrafine and Fine Particles and Hospital Admissions in Central Europe Results from the UFIREG Study

    Czech Academy of Sciences Publication Activity Database

    Lanzinger, S.; Schneider, A.; Breitner, S.; Stafoggia, M.; Erzen, I.; Dostál, Miroslav; Pastorková, Anna; Bastian, S.; Cyrys, J.; Zscheppang, A.; Kolodnitská, T.; Peters, A.

    2016-01-01

    Roč. 194, č. 10 (2016), s. 1233-1241 ISSN 1073-449X Institutional support: RVO:68378041 Keywords : ultrafine particles * particulate matter * hospital admissions * respiratory Subject RIV: DN - Health Impact of the Environment Quality Impact factor: 13.204, year: 2016

  5. Size evolution of ultrafine particles: Differential signatures of normal and episodic events

    International Nuclear Information System (INIS)

    Joshi, Manish; Khan, Arshad; Anand, S.; Sapra, B.K.

    2016-01-01

    The effect of fireworks on the aerosol number characteristics of atmosphere was studied for an urban mega city. Measurements were made at 50 m height to assess the local changes around the festival days. Apart from the increase in total number concentration and characteristic accumulation mode, short-term increase of ultrafine particle concentration was noted. Total number concentration varies an order of magnitude during the measurement period in which peak occurs at a frequency of approximately one per day. On integral scale, it seems not possible to distinguish an episodic (e.g. firework bursting induced aerosol emission) and a normal (ambient atmospheric changes) event. However these events could be differentiated on the basis of size evolution analysis around number concentration peaks. The results are discussed relative to past studies and inferences are drawn towards aerosol signatures of firework bursting. The short-term burst in ultrafine particle concentration can pose an inhalation hazard. - Highlights: • Effect of firework emissions on atmospheric aerosol characteristics was studied. • Significant increase in ultrafine particle concentration was observed during firework bursting. • Size distribution evolution analysis of number concentration peaks has been performed. • Differential signatures of normal and episodic event were noted. - Notable increase in ultrafine particle concentration during firework bursting was seen. Normal and episodic event could be differentiated on the basis of size evolution analysis.

  6. Effect of flow characteristics on ultrafine particle emissions from range hoods.

    Science.gov (United States)

    Tseng, Li-Ching; Chen, Chih-Chieh

    2013-08-01

    In order to understand the physical mechanisms of the production of nanometer-sized particulate generated from cooking oils, the ventilation of kitchen hoods was studied by determining the particle concentration, particle size distribution, particle dimensions, and hood's flow characteristics under several cooking scenarios. This research varied the temperature of the frying operation on one cooking operation, with three kinds of commercial cooking oils including soybean oil, olive oil, and sunflower oil. The variations of particle concentration and size distributions with the elevated cooking oil temperatures were presented. The particle concentration increases as a function of temperature. For oil temperatures ranging between 180°C and 210°C, a 5°C increase in temperature increased the number concentration of ultrafine particles by 20-50%. The maximum concentration of ultrafine particles was found to be approximately 6 × 10(6) particles per cm(3) at 260°C. Flow visualization techniques and particle distribution measurement were performed for two types of hood designs, a wall-mounted range hood and an island hood, at a suction flow rate of 15 m(3) min(-1). The flow visualization results showed that different configurations of kitchen hoods induce different aerodynamic characteristics. By comparing the results of flow visualizations and nanoparticle measurements, it was found that the areas with large-scale turbulent vortices are more prone to dispersion of ultrafine particle leakage because of the complex interaction between the shear layers and the suction movement that results from turbulent dispersion. We conclude that the evolution of ultrafine particle concentration fluctuations is strongly affected by the location of the hood, which can alter the aerodynamic features. We suggest that there is a correlation between flow characteristics and amount of contaminant leakage. This provides a comprehensive strategy to evaluate the effectiveness of kitchen hoods

  7. Preparation and Hydrogen Storage Properties of Mg-Rich Mg-Ni Ultrafine Particles

    Directory of Open Access Journals (Sweden)

    Jianxin Zou

    2012-01-01

    Full Text Available In the present work, Mg-rich Mg-Ni ultrafine powders were prepared through an arc plasma method. The phase components, microstructure, and hydrogen storage properties of the powders were carefully investigated. It is found that Mg2Ni and MgNi2 could be obtained directly from the vapor state reactions between Mg and Ni, depending on the local vapor content in the reaction chamber. A nanostructured MgH2 + Mg2NiH4 hydrogen storage composite could be generated after hydrogenation of the Mg-Ni ultrafine powders. After dehydrogenation, MgH2 and Mg2NiH4 decomposed into nanograined Mg and Mg2Ni, respectively. Thermogravimetry/differential scanning calorimetry (TG/DSC analyses showed that Mg2NiH4 phase may play a catalytic role in the dehydriding process of the hydrogenated Mg ultrafine particles.

  8. Number size distribution of fine and ultrafine fume particles from various welding processes.

    Science.gov (United States)

    Brand, Peter; Lenz, Klaus; Reisgen, Uwe; Kraus, Thomas

    2013-04-01

    Studies in the field of environmental epidemiology indicate that for the adverse effect of inhaled particles not only particle mass is crucial but also particle size is. Ultrafine particles with diameters below 100 nm are of special interest since these particles have high surface area to mass ratio and have properties which differ from those of larger particles. In this paper, particle size distributions of various welding and joining techniques were measured close to the welding process using a fast mobility particle sizer (FMPS). It turned out that welding processes with high mass emission rates (manual metal arc welding, metal active gas welding, metal inert gas welding, metal inert gas soldering, and laser welding) show mainly agglomerated particles with diameters above 100 nm and only few particles in the size range below 50 nm (10 to 15%). Welding processes with low mass emission rates (tungsten inert gas welding and resistance spot welding) emit predominantly ultrafine particles with diameters well below 100 nm. This finding can be explained by considerably faster agglomeration processes in welding processes with high mass emission rates. Although mass emission is low for tungsten inert gas welding and resistance spot welding, due to the low particle size of the fume, these processes cannot be labeled as toxicologically irrelevant and should be further investigated.

  9. Aerosol number size distributions over a coastal semi urban location: Seasonal changes and ultrafine particle bursts

    International Nuclear Information System (INIS)

    Babu, S. Suresh; Kompalli, Sobhan Kumar; Moorthy, K. Krishna

    2016-01-01

    Number-size distribution is one of the important microphysical properties of atmospheric aerosols that influence aerosol life cycle, aerosol-radiation interaction as well as aerosol-cloud interactions. Making use of one-yearlong measurements of aerosol particle number-size distributions (PNSD) over a broad size spectrum (~ 15–15,000 nm) from a tropical coastal semi-urban location-Trivandrum (Thiruvananthapuram), the size characteristics, their seasonality and response to mesoscale and synoptic scale meteorology are examined. While the accumulation mode contributed mostly to the annual mean concentration, ultrafine particles (having diameter < 100 nm) contributed as much as 45% to the total concentration, and thus constitute a strong reservoir, that would add to the larger particles through size transformation. The size distributions were, in general, bimodal with well-defined modes in the accumulation and coarse regimes, with mode diameters lying in the range 141 to 167 nm and 1150 to 1760 nm respectively, in different seasons. Despite the contribution of the coarse sized particles to the total number concentration being meager, they contributed significantly to the surface area and volume, especially during transport of marine air mass highlighting the role of synoptic air mass changes. Significant diurnal variation occurred in the number concentrations, geometric mean diameters, which is mostly attributed to the dynamics of the local coastal atmospheric boundary layer and the effect of mesoscale land/sea breeze circulation. Bursts of ultrafine particles (UFP) occurred quite frequently, apparently during periods of land-sea breeze transitions, caused by the strong mixing of precursor-rich urban air mass with the cleaner marine air mass; the resulting turbulence along with boundary layer dynamics aiding the nucleation. These ex-situ particles were observed at the surface due to the transport associated with boundary layer dynamics. The particle growth rates from

  10. Aerosol number size distributions over a coastal semi urban location: Seasonal changes and ultrafine particle bursts

    Energy Technology Data Exchange (ETDEWEB)

    Babu, S. Suresh, E-mail: s_sureshbabu@vssc.gov.in [Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram 695022 (India); Kompalli, Sobhan Kumar [Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram 695022 (India); Moorthy, K. Krishna [Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore 560 012 (India)

    2016-09-01

    Number-size distribution is one of the important microphysical properties of atmospheric aerosols that influence aerosol life cycle, aerosol-radiation interaction as well as aerosol-cloud interactions. Making use of one-yearlong measurements of aerosol particle number-size distributions (PNSD) over a broad size spectrum (~ 15–15,000 nm) from a tropical coastal semi-urban location-Trivandrum (Thiruvananthapuram), the size characteristics, their seasonality and response to mesoscale and synoptic scale meteorology are examined. While the accumulation mode contributed mostly to the annual mean concentration, ultrafine particles (having diameter < 100 nm) contributed as much as 45% to the total concentration, and thus constitute a strong reservoir, that would add to the larger particles through size transformation. The size distributions were, in general, bimodal with well-defined modes in the accumulation and coarse regimes, with mode diameters lying in the range 141 to 167 nm and 1150 to 1760 nm respectively, in different seasons. Despite the contribution of the coarse sized particles to the total number concentration being meager, they contributed significantly to the surface area and volume, especially during transport of marine air mass highlighting the role of synoptic air mass changes. Significant diurnal variation occurred in the number concentrations, geometric mean diameters, which is mostly attributed to the dynamics of the local coastal atmospheric boundary layer and the effect of mesoscale land/sea breeze circulation. Bursts of ultrafine particles (UFP) occurred quite frequently, apparently during periods of land-sea breeze transitions, caused by the strong mixing of precursor-rich urban air mass with the cleaner marine air mass; the resulting turbulence along with boundary layer dynamics aiding the nucleation. These ex-situ particles were observed at the surface due to the transport associated with boundary layer dynamics. The particle growth rates from

  11. Increased ultrafine particles and carbon monoxide concentrations are associated with asthma exacerbation among urban children

    Science.gov (United States)

    Evans, Kristin A.; Halterman, Jill S.; Hopke, Philip K.; Fagnano, Maria; Rich, David Q.

    2014-01-01

    Objectives Increased air pollutant concentrations have been linked to several asthma-related outcomes in children, including respiratory symptoms, medication use, and hospital visits. However, few studies have examined effects of ultrafine particles in a pediatric population. Our primary objective was to examine the effects of ambient concentrations of ultrafine particles on asthma exacerbation among urban children and determine whether consistent treatment with inhaled corticosteroids could attenuate these effects. We also explored the relationship between asthma exacerbation and ambient concentrations of accumulation mode particles, fine particles (≤ 2.5 micrograms [μm]; PM2.5), carbon monoxide, sulfur dioxide, and ozone. We hypothesized that increased 1 to 7 day concentrations of ultrafine particles and other pollutants would be associated with increases in the relative odds of an asthma exacerbation, but that this increase in risk would be attenuated among children receiving school-based corticosteroid therapy. Methods We conducted a pilot study using data from 3–10 year-old children participating in the School-Based Asthma Therapy trial. Using a time-stratified case-crossover design and conditional logistic regression, we estimated the relative odds of a pediatric asthma visit treated with prednisone (n=96 visits among 74 children) associated with increased pollutant concentrations in the previous 7 days. We re-ran these analyses separately for children receiving medications through the school-based intervention and children in a usual care control group. Results Interquartile range increases in ultrafine particles and carbon monoxide concentrations in the previous 7 days were associated with increases in the relative odds of a pediatric asthma visit, with the largest increases observed for 4-day mean ultrafine particles (interquartile range=2088 p/cm3; OR=1.27; 95% CI=0.90–1.79) and 7-day mean carbon monoxide (interquartile range=0.17 ppm; OR=1.63; 95

  12. Summertime observations of elevated levels of ultrafine particles in the high Arctic marine boundary layer

    Science.gov (United States)

    Burkart, Julia; Willis, Megan D.; Bozem, Heiko; Thomas, Jennie L.; Law, Kathy; Hoor, Peter; Aliabadi, Amir A.; Köllner, Franziska; Schneider, Johannes; Herber, Andreas; Abbatt, Jonathan P. D.; Leaitch, W. Richard

    2017-05-01

    Motivated by increasing levels of open ocean in the Arctic summer and the lack of prior altitude-resolved studies, extensive aerosol measurements were made during 11 flights of the NETCARE July 2014 airborne campaign from Resolute Bay, Nunavut. Flights included vertical profiles (60 to 3000 m above ground level) over open ocean, fast ice, and boundary layer clouds and fogs. A general conclusion, from observations of particle numbers between 5 and 20 nm in diameter (N5 - 20), is that ultrafine particle formation occurs readily in the Canadian high Arctic marine boundary layer, especially just above ocean and clouds, reaching values of a few thousand particles cm-3. By contrast, ultrafine particle concentrations are much lower in the free troposphere. Elevated levels of larger particles (for example, from 20 to 40 nm in size, N20 - 40) are sometimes associated with high N5 - 20, especially over low clouds, suggestive of aerosol growth. The number densities of particles greater than 40 nm in diameter (N > 40) are relatively depleted at the lowest altitudes, indicative of depositional processes that will lower the condensation sink and promote new particle formation. The number of cloud condensation nuclei (CCN; measured at 0.6 % supersaturation) are positively correlated with the numbers of small particles (down to roughly 30 nm), indicating that some fraction of these newly formed particles are capable of being involved in cloud activation. Given that the summertime marine Arctic is a biologically active region, it is important to better establish the links between emissions from the ocean and the formation and growth of ultrafine particles within this rapidly changing environment.

  13. Impact of two particle measurement techniques on the determination of N95 class respirator filtration performance against ultrafine particles

    International Nuclear Information System (INIS)

    Mostofi, Reza; Noël, Alexandra; Haghighat, Fariborz; Bahloul, Ali; Lara, Jaime; Cloutier, Yves

    2012-01-01

    Highlights: ► Performance evaluation of respirator using two different measurement techniques. ► Impaction and electrical mobility were used to characterize ultrafine particle. ► The experiment was done using ultrafine-sized poly-dispersed aerosols. ► Both techniques show that MPPS would occur at a similar size range. - Abstract: The purpose of this experimental study was to compare two different particle measurement devices; an Electrical Low Pressure Impactor (ELPI) and a Scanning Mobility Particle Sizer (SMPS), to measure the number concentration and the size distribution of NaCl salt aerosols to determine the collection efficiency of filtering respirators against poly disperse aerosols. Tests were performed on NIOSH approved N95 filtering face-piece respirators (FFR), sealed on a manikin head. Ultrafine particles found in the aerosols were also collected and observed by transmission electron microscopy (TEM). According to the results, there is a systematic difference for the particle size distribution measured by the SMPS and the ELPI. It is largely attributed to the difference in the measurement techniques. However, in spite of these discrepancies, reasonably similar trends were found for the number concentration with both measuring instruments. The particle penetration, calculated based on mobility and aerodynamic diameters, never exceeded 5% for any size range measured at constant flow rate of 85 L/min. Also, the most penetrating particle size (MPPS), with the lowest filtration efficiency, would occur at a similar ultrafine size range <100 nm. With the ELPI, the MPPS was at 70 nm aerodynamic diameter, whereas it occurred at 40 nm mobility diameter with the SMPS.

  14. Size evolution of ultrafine particles: Differential signatures of normal and episodic events.

    Science.gov (United States)

    Joshi, Manish; Khan, Arshad; Anand, S; Sapra, B K

    2016-01-01

    The effect of fireworks on the aerosol number characteristics of atmosphere was studied for an urban mega city. Measurements were made at 50 m height to assess the local changes around the festival days. Apart from the increase in total number concentration and characteristic accumulation mode, short-term increase of ultrafine particle concentration was noted. Total number concentration varies an order of magnitude during the measurement period in which peak occurs at a frequency of approximately one per day. On integral scale, it seems not possible to distinguish an episodic (e.g. firework bursting induced aerosol emission) and a normal (ambient atmospheric changes) event. However these events could be differentiated on the basis of size evolution analysis around number concentration peaks. The results are discussed relative to past studies and inferences are drawn towards aerosol signatures of firework bursting. The short-term burst in ultrafine particle concentration can pose an inhalation hazard. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Ultrafine carbon particles promote rotenone-induced dopamine neuronal loss through activating microglial NADPH oxidase

    International Nuclear Information System (INIS)

    Wang, Yinxi; Liu, Dan; Zhang, Huifeng; Wang, Yixin; Wei, Ling; Liu, Yutong; Liao, Jieying; Gao, Hui-Ming; Zhou, Hui

    2017-01-01

    Background: Atmospheric ultrafine particles (UFPs) and pesticide rotenone were considered as potential environmental risk factors for Parkinson's disease (PD). However, whether and how UFPs alone and in combination with rotenone affect the pathogenesis of PD remains largely unknown. Methods: Ultrafine carbon black (ufCB, a surrogate of UFPs) and rotenone were used individually or in combination to determine their roles in chronic dopaminergic (DA) loss in neuron-glia, and neuron-enriched, mix-glia cultures. Immunochemistry using antibody against tyrosine hydroxylase was performed to detect DA neuronal loss. Measurement of extracellular superoxide and intracellular reactive oxygen species (ROS) were performed to examine activation of NADPH oxidase. Genetic deletion and pharmacological inhibition of NADPH oxidase and MAC-1 receptor in microglia were employed to examine their role in DA neuronal loss triggered by ufCB and rotenone. Results: In rodent midbrain neuron-glia cultures, ufCB and rotenone alone caused neuronal death in a dose-dependent manner. In particularly, ufCB at doses of 50 and 100 μg/cm 2 induced significant loss of DA neurons. More importantly, nontoxic doses of ufCB (10 μg/cm 2 ) and rotenone (2 nM) induced synergistic toxicity to DA neurons. Microglial activation was essential in this process. Furthermore, superoxide production from microglial NADPH oxidase was critical in ufCB/rotenone-induced neurotoxicity. Studies in mix-glia cultures showed that ufCB treatment activated microglial NADPH oxidase to induce superoxide production. Firstly, ufCB enhanced the expression of NADPH oxidase subunits (gp91 phox , p47 phox and p40 phox ); secondly, ufCB was recognized by microglial surface MAC-1 receptor and consequently promoted rotenone-induced p47 phox and p67 phox translocation assembling active NADPH oxidase. Conclusion: ufCB and rotenone worked in synergy to activate NADPH oxidase in microglia, leading to oxidative damage to DA neurons. Our

  16. Ultrafine carbon particles promote rotenone-induced dopamine neuronal loss through activating microglial NADPH oxidase

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yinxi; Liu, Dan; Zhang, Huifeng; Wang, Yixin [Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, 100191 (China); Wei, Ling [Beijing Center for Physical & Chemical Analysis, Beijing 100089 (China); Liu, Yutong [School of Life Science, Beijing Normal University, Beijing 100875 (China); Liao, Jieying [Department of Translational Medicine, Xiamen Institute of Rare Earth Materials, Chinese Academy of Sciences, Xiamen 361024 (China); Gao, Hui-Ming [Model Animal Research Center of Nanjing University, Nanjing 211800 (China); Zhou, Hui, E-mail: hardhui@gmail.com [Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, 100191 (China)

    2017-05-01

    Background: Atmospheric ultrafine particles (UFPs) and pesticide rotenone were considered as potential environmental risk factors for Parkinson's disease (PD). However, whether and how UFPs alone and in combination with rotenone affect the pathogenesis of PD remains largely unknown. Methods: Ultrafine carbon black (ufCB, a surrogate of UFPs) and rotenone were used individually or in combination to determine their roles in chronic dopaminergic (DA) loss in neuron-glia, and neuron-enriched, mix-glia cultures. Immunochemistry using antibody against tyrosine hydroxylase was performed to detect DA neuronal loss. Measurement of extracellular superoxide and intracellular reactive oxygen species (ROS) were performed to examine activation of NADPH oxidase. Genetic deletion and pharmacological inhibition of NADPH oxidase and MAC-1 receptor in microglia were employed to examine their role in DA neuronal loss triggered by ufCB and rotenone. Results: In rodent midbrain neuron-glia cultures, ufCB and rotenone alone caused neuronal death in a dose-dependent manner. In particularly, ufCB at doses of 50 and 100 μg/cm{sup 2} induced significant loss of DA neurons. More importantly, nontoxic doses of ufCB (10 μg/cm{sup 2}) and rotenone (2 nM) induced synergistic toxicity to DA neurons. Microglial activation was essential in this process. Furthermore, superoxide production from microglial NADPH oxidase was critical in ufCB/rotenone-induced neurotoxicity. Studies in mix-glia cultures showed that ufCB treatment activated microglial NADPH oxidase to induce superoxide production. Firstly, ufCB enhanced the expression of NADPH oxidase subunits (gp91{sup phox}, p47{sup phox} and p40{sup phox}); secondly, ufCB was recognized by microglial surface MAC-1 receptor and consequently promoted rotenone-induced p47{sup phox} and p67{sup phox} translocation assembling active NADPH oxidase. Conclusion: ufCB and rotenone worked in synergy to activate NADPH oxidase in microglia, leading to

  17. Exposure to ultrafine particles and respiratory hospitalisations in five European cities

    DEFF Research Database (Denmark)

    Samoli, Evangelia; Andersen, Zorana Jovanovic; Katsouyanni, Klea

    2016-01-01

    Epidemiological evidence on the associations between exposure to ultrafine particles (UFP), with aerodynamic electrical mobility diameters <100 nm, and health is limited. We gathered data on UFP from five European cities within 2001-2011 to investigate associations between short-term changes in c...... period may reflect better exposure assessment and that the main source of non-soluble UFP in urban areas is traffic, our results call for improved regulation of traffic emissions....

  18. Personal exposure to airborne ultrafine particles in the urban area of Milan

    Science.gov (United States)

    Cattaneo, A.; Garramone, G.; Taronna, M.; Peruzzo, C.; Cavallo, D. M.

    2009-02-01

    The relevance of health effects related to ultrafine particles (UFPs; aerodynamic diameter car), indicating that the highest exposure to UFPs can be reached near motorized traffic. The lowest exposures were observed in green areas and in office microenvironments. An appreciable difference between working and non-working days was observed. Concentration patterns and variation by days of the week and time periods appears related to time trends in traffic intensity.

  19. Photochemical synthesis of ultrafine organosilicon particles from trimethyl(2-propynyloxy)silane and carbon disulfide

    Czech Academy of Sciences Publication Activity Database

    Morita, H.; Nozawa, R.; Bastl, Zdeněk; Šubrt, Jan; Pola, Josef

    2006-01-01

    Roč. 179, 1-2 (2006), s. 142-148 ISSN 1010-6030 Grant - others:MEXT(JP) 767/15085203 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z40320502; CEZ:AV0Z40720504 Keywords : ultrafine particles * photo-polymerization * trimethyl(2-propynyloxy)silane * carbon disulfide Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.098, year: 2006

  20. Translocation and potential neurological effects of fine and ultrafine particles a critical update.

    Science.gov (United States)

    Peters, Annette; Veronesi, Bellina; Calderón-Garcidueñas, Lilian; Gehr, Peter; Chen, Lung Chi; Geiser, Marianne; Reed, William; Rothen-Rutishauser, Barbara; Schürch, Samuel; Schulz, Holger

    2006-09-08

    Particulate air pollution has been associated with respiratory and cardiovascular disease. Evidence for cardiovascular and neurodegenerative effects of ambient particles was reviewed as part of a workshop. The purpose of this critical update is to summarize the evidence presented for the mechanisms involved in the translocation of particles from the lung to other organs and to highlight the potential of particles to cause neurodegenerative effects. Fine and ultrafine particles, after deposition on the surfactant film at the air-liquid interface, are displaced by surface forces exerted on them by surfactant film and may then interact with primary target cells upon this displacement. Ultrafine and fine particles can then penetrate through the different tissue compartments of the lungs and eventually reach the capillaries and circulating cells or constituents, e.g. erythrocytes. These particles are then translocated by the circulation to other organs including the liver, the spleen, the kidneys, the heart and the brain, where they may be deposited. It remains to be shown by which mechanisms ultrafine particles penetrate through pulmonary tissue and enter capillaries. In addition to translocation of ultrafine particles through the tissue, fine and coarse particles may be phagocytized by macrophages and dendritic cells which may carry the particles to lymph nodes in the lung or to those closely associated with the lungs. There is the potential for neurodegenerative consequence of particle entry to the brain. Histological evidence of neurodegeneration has been reported in both canine and human brains exposed to high ambient PM levels, suggesting the potential for neurotoxic consequences of PM-CNS entry. PM mediated damage may be caused by the oxidative stress pathway. Thus, oxidative stress due to nutrition, age, genetics among others may increase the susceptibility for neurodegenerative diseases. The relationship between PM exposure and CNS degeneration can also be

  1. Ultrafine particles of Ni and FeCr studied by positron annihilation

    DEFF Research Database (Denmark)

    Eldrup, Morten Mostgaard; Pedersen, N.J.; Sethi, S.A.

    1995-01-01

    Ultrafine particles of Ni and Fe80Cr20 have been produced by the gas condensation technique. After surface oxidation the paticles were heated in a reducing H2 atmosphere and positron lifetime and Doppler broadening measurements were carried out. Reduction of the oxide on the Ni powder takes place...... at about 350K and at about 650K for the FeCr powder. Electron microscopy shows sintering of the Ni particles above 450K, and the present results show that defects develop in the growing particles....

  2. Correlation of Air Quality Data to Ultrafine Particles (UFP Concentration and Size Distribution in Ambient Air

    Directory of Open Access Journals (Sweden)

    Werner Hofmann

    2010-07-01

    Full Text Available This study monitored ultrafine particles (UFP concurrent with environmental air quality data, investigating whether already existing instrumentation used by environmental authorities can provide reference values for estimating UFP concentrations. Of particular interest was the relation of UFP to PM10 (particulate matter and nitrogen oxides (NOx, NO2 in ambient air. Existing PM measurement methods alone did not correspond exactly enough with the actual particle number, but we observed a link between NOx and NO2 to UFP concentration. The combined data could act as proxy-indicator for authorities in estimating particle number concentrations, but cannot replace UFP monitoring.

  3. REAL TIME MEASUREMENT OF ULTRAFINE AND NANO PARTICLES AND SIGNIFICANCE OF OPERATING GEARS

    Directory of Open Access Journals (Sweden)

    H. A. NAKHAWA

    2017-03-01

    Full Text Available This research paper focuses on characterization of ultrafine and nanoparticle emissions from diesel vehicle to investigate their physical characterization in terms of number and size as they are more vulnerable and responsible for toxicity, mutagenicity and carcinogenicity. An investigation has been carried out to identify the significance of different operating gears, clutch, declutch and gear change operations for their contributions to particle number(PN on urban and extra urban part of the driving cycle. A bi-modal particle size distribution pattern was observed for both urban and extra urban parts where almost all the particles are below 200 nm and particle number peaks appear at 7 to 8 nm and at 70 nm. Nano particles contribute approximately, 70% of total particle number over urban part. Experimental investigation shows that the most significant gear for their contribution to particle number are 3rd and 5th gears on urban and extra urban part of the driving cycle respectively.

  4. Association between short-term exposure to ultrafine particles and mortality in eight European urban areas

    DEFF Research Database (Denmark)

    Stafoggia, Massimo; Schneider, Alexandra; Cyrys, Josef

    2017-01-01

    urban areas of Finland, Sweden, Denmark, Germany, Italy, Spain, and Greece, between 1999 and 2013. We applied city-specific time-series Poisson regression models and pooled them with random-effects meta-analysis. RESULTS: We estimated a weak, delayed association between particle number concentration...... and particulate matter (PM) and daily mortality in eight European urban areas. METHODS: We collected daily data on non-accidental and cardio-respiratory mortality, particle number concentrations (as proxy for ultrafine particle number concentration), fine and coarse PM, gases and meteorologic parameters in eight...... and non-accidental mortality, with mortality increasing by approximately 0.35% per 10,000 particles/cm increases in particle number concentration occurring 5 to 7 days before death. A similar pattern was found for cause-specific mortality. Estimates decreased after adjustment for fine particles (PM2...

  5. Ultrafine particles from power plants: Evaluation of WRF-Chem simulations with airborne measurements

    Science.gov (United States)

    Forkel, Renate; Junkermann, Wolfgang

    2017-04-01

    Ultrafine particles (UFP, particles with a diameter risk to human health and have a potential effect on climate as their presence affects the number concentration of cloud condensation nuclei. Despite of the possibly hazardous effects no regulations exist for this size class of ambient air pollution particles. While ground based continuous measurements of UFP are performed in Germany at several sites (e.g. the German Ultrafine Aerosol Network GUAN, Birmili et al. 2016, doi:10.5194/essd-8-355-2016) information about the vertical distribution of UFP within the atmospheric boundary layer is only scarce. This gap has been closed during the last years by regional-scale airborne surveys for UFP concentrations and size distributions over Germany (Junkermann et al., 2016, doi: 10.3402/tellusb.v68.29250) and Australia (Junkermann and Hacker, 2015, doi: 10.3402/tellusb.v67.25308). Power stations and refineries have been identified as a major source of UFP in Germany with observed particle concentrations > 50000 particles cm-3 downwind of these elevated point sources. Nested WRF-Chem simulations with 2 km grid width for the innermost domain are performed with UFP emission source strengths derived from the measurements in order to study the advection and vertical exchange of UFP from power plants near the Czech and Polish border and their impact on planetary boundary layer particle patterns. The simulations are evaluated against the airborne observations and the downward mixing of the UFP from the elevated sources is studied.

  6. On the time-averaging of ultrafine particle number size spectra in vehicular plumes

    Directory of Open Access Journals (Sweden)

    X. H. Yao

    2006-01-01

    Full Text Available Ultrafine vehicular particle (<100 nm number size distributions presented in the literature are mostly averages of long scan-time (~30 s or more spectra mainly due to the non-availability of commercial instruments that can measure particle distributions in the <10 nm to 100 nm range faster than 30 s even though individual researchers have built faster (1–2.5 s scanning instruments. With the introduction of the Engine Exhaust Particle Sizer (EEPS in 2004, high time-resolution (1 full 32-channel spectrum per second particle size distribution data become possible and allow atmospheric researchers to study the characteristics of ultrafine vehicular particles in rapidly and perhaps randomly varying high concentration environments such as roadside, on-road and tunnel. In this study, particle size distributions in these environments were found to vary as rapidly as one second frequently. This poses the question on the generality of using averages of long scan-time spectra for dynamic and/or mechanistic studies in rapidly and perhaps randomly varying high concentration environments. One-second EEPS data taken at roadside, on roads and in tunnels by a mobile platform are time-averaged to yield 5, 10, 30 and 120 s distributions to answer this question.

  7. Exposure to ultrafine particles in relation to indoor events and dwelling characteristics

    DEFF Research Database (Denmark)

    Spilak, Michal; Frederiksen, Marie; Kolarik, Barbara

    2014-01-01

    Exposure to ultrafine particles (UFP) in homes is associated with health risks such as cardiovascular disease and/or respiratory problems. These risks are heightened by the long time that people spend indoors. Therefore reducing the particle concentration in homes leads to improved health among its....... Furthermore, the winter season was associated significantly with high UFP levels indoors. Results of our study also indicated that owning a pet, wood-type floors and floor levels close to the ground are associated with increased UFP levels....

  8. A system for aerodynamically sizing ultrafine environmental radioactive particles

    International Nuclear Information System (INIS)

    Olawoyin, L.

    1995-09-01

    The unattached environmental radioactive particles/clusters, produced mainly by 222 Rn in indoor air, are usually few nanometers in size. The inhalation of these radioactive clusters can lead to deposition of radioactivity on the mucosal surface of the tracheobronchial tree. The ultimate size of the cluster together with the flow characteristics will determine the depositional site in the human lung and thus, the extent of damage that can be caused. Thus, there exists the need for the determination of the size of the radioactive clusters. However, the existing particle measuring device have low resolution in the sub-nanometer range. In this research, a system for the alternative detection and measurement of the size of particles/cluster in the less than 2 nm range have been developed. The system is a one stage impactor which has a solid state spectrometer as its impaction plate. It's major feature is the nozzle-to-plate separation, L. The particle size collected changes with L and thus, particle size spectroscopy is achieved by varying L. The number of collected particles is determined by alpha spectroscopy. The size-discriminating ability of the system was tested with laboratory generated radon particles and it was subsequently used to characterize the physical (size) changes associated with the interaction of radon progeny with water vapor and short chain alcohols in various support gases. The theory of both traditional and high velocity jet impactors together with the design and evaluation of the system developed in this study are discussed in various chapters of this dissertation. The major results obtained in the course of the study are also presented

  9. A system for aerodynamically sizing ultrafine environmental radioactive particles

    Energy Technology Data Exchange (ETDEWEB)

    Olawoyin, L.

    1995-09-01

    The unattached environmental radioactive particles/clusters, produced mainly by {sup 222}Rn in indoor air, are usually few nanometers in size. The inhalation of these radioactive clusters can lead to deposition of radioactivity on the mucosal surface of the tracheobronchial tree. The ultimate size of the cluster together with the flow characteristics will determine the depositional site in the human lung and thus, the extent of damage that can be caused. Thus, there exists the need for the determination of the size of the radioactive clusters. However, the existing particle measuring device have low resolution in the sub-nanometer range. In this research, a system for the alternative detection and measurement of the size of particles/cluster in the less than 2 nm range have been developed. The system is a one stage impactor which has a solid state spectrometer as its impaction plate. It`s major feature is the nozzle-to-plate separation, L. The particle size collected changes with L and thus, particle size spectroscopy is achieved by varying L. The number of collected particles is determined by alpha spectroscopy. The size-discriminating ability of the system was tested with laboratory generated radon particles and it was subsequently used to characterize the physical (size) changes associated with the interaction of radon progeny with water vapor and short chain alcohols in various support gases. The theory of both traditional and high velocity jet impactors together with the design and evaluation of the system developed in this study are discussed in various chapters of this dissertation. The major results obtained in the course of the study are also presented.

  10. Exposure to diesel exhaust fumes in the context of exposure to ultrafine particles

    Directory of Open Access Journals (Sweden)

    Stella Bujak-Pietrek

    2016-08-01

    Full Text Available Objectives: Diesel exhaust fumes emission is a significant source of ultrafine particles, the size of which is expressed in nanometers. People occupationally exposed to diesel exhaust particles include mainly workers servicing vehicles with engines of this type. This article presents the analysis of measurements of ultrafine particle concentrations occurring in the bus depot premises during the work connected with everyday technical servicing of buses. Material and Methods: The measurements were carried out in the everyday servicing (ES room of the bus depot before, during and after the work connected with bus servicing. Determinations included: particle concentrations in terms of particle number and particle surface area, and mass concentrations of aerosol. Results: Mean value of number concentration of 10- to 1000-nm particles increased almost 20-fold, from 7600 particles/cm3 before starting bus servicing procedures to 130 000 particles/cm3 during the bus servicing procedures in the room. During the procedures, the mean surface area concentration of particles potentially deposited in the alveolar (A region was almost 3 times higher than that of the particles depositing in the tracheo-bronchial (TB region: 356.46 μm2/cm3 vs. 95.97 μm2/cm3, respectively. The mass concentration of the fraction of particulate matter with aerodynamic diameter 0.02–1 μm (PM1 increased 5-fold during the analyzed procedures and was 0.042 mg/m3 before, and 0.298 mg/m3 while the procedures continued. Conclusions: At the time when bus servicing procedures continued in the ES room, a very high increase in all parameters of the analyzed particles was observed. The diesel exhaust particles exhibit a very high degree of fragmentation and, while their number is very high and their surface area is very large, their mass concentration is relatively low. The above findings confirm that ultrafine particles found in diesel exhaust fumes may be harmful to the health of the

  11. Facile Deposition of Ultrafine Silver Particles on Silicon Surface Not Submerged in Precursor Solutions for Applications in Antireflective Layer

    Directory of Open Access Journals (Sweden)

    Bing Jiang

    2014-01-01

    Full Text Available Using a facile deposition method, the ultrafine silver particles are successfully deposited on the Si surface that is not submerged in precursor solutions. The ultrafine silver particles have many advantages, such as quasiround shape, uniformity in size, monodisperse distribution, and reduction of agglomeration. The internal physical procedure in the deposition is also investigated. The results show that there are more particles on the rough Si surface due to the wetting effect of solid-liquid interface. The higher concentration of ethanol solvent can induce the increase of quantity and size of particles on Si surface not in solutions. The ultrafine particles can be used to prepare porous Si antireflective layer in solar cell applications.

  12. Ultrafine particles in inhabited areas in the Arctic - From very low to high concentrations

    DEFF Research Database (Denmark)

    Pétursdóttir, Una; Kirkelund, Gunvor Marie; Press-Kristensen, Kåre

    2017-01-01

    The Arctic is considered a pristine environment, where pollution mainly originates from global sources. The present study examines particle number concentrations (PNCs) and the main sources of airborne ultrafine particles (UFPs, d < 100 nm) in the town Sisimiut and two nearby settlements, Sarfann......The Arctic is considered a pristine environment, where pollution mainly originates from global sources. The present study examines particle number concentrations (PNCs) and the main sources of airborne ultrafine particles (UFPs, d ..., Sarfannguit and Itilleq, in West Greenland. Measurements were carried out during three weeks in April and May 2016. Air temperatures during the measurements ranged from −4.4 to +8.7 °C. A portable condensation particle counter (P-Trak) was used for the measurements. Results showed that the lowest...... in Sisimiut, while subsequent measurements at the same location showed much lower PNCs. The presence of heavy machinery elevated PNCs highly during two measurement events, giving PNCs up to 270,993 cm−3 but dropping to 1180 cm−3 10 min later, after the vehicle had passed by. A measurement event in Sisimiut...

  13. Ultrafine particles cause cytoskeletal dysfunctions in macrophages: role of intracellular calcium

    Directory of Open Access Journals (Sweden)

    Brown David M

    2005-10-01

    Full Text Available Abstract Background Particulate air pollution is reported to cause adverse health effects in susceptible individuals. Since most of these particles are derived form combustion processes, the primary composition product is carbon with a very small diameter (ultrafine, less than 100 nm in diameter. Besides the induction of reactive oxygen species and inflammation, ultrafine particles (UFP can cause intracellular calcium transients and suppression of defense mechanisms of alveolar macrophages, such as impaired migration or phagocytosis. Methods In this study the role of intracellular calcium transients caused by UFP was studied on cytoskeleton related functions in J774A.1 macrophages. Different types of fine and ultrafine carbon black particles (CB and ufCB, respectively, such as elemental carbon (EC90, commercial carbon (Printex 90, diesel particulate matter (DEP and urban dust (UD, were investigated. Phagosome transport mechanisms and mechanical cytoskeletal integrity were studied by cytomagnetometry and cell viability was studied by fluorescence microscopy. Macrophages were exposed in vitro with 100 and 320 μg UFP/ml/million cells for 4 hours in serum free medium. Calcium antagonists Verapamil, BAPTA-AM and W-7 were used to block calcium channels in the membrane, to chelate intracellular calcium or to inhibit the calmodulin signaling pathways, respectively. Results Impaired phagosome transport and increased cytoskeletal stiffness occurred at EC90 and P90 concentrations of 100 μg/ml/million cells and above, but not with DEP or UD. Verapamil and W-7, but not BAPTA-AM inhibited the cytoskeletal dysfunctions caused by EC90 or P90. Additionally the presence of 5% serum or 1% bovine serum albumin (BSA suppressed the cytoskeletal dysfunctions. Cell viability showed similar results, where co-culture of ufCB together with Verapamil, W-7, FCS or BSA produced less cell dead compared to the particles only.

  14. Individual dose and exposure of Italian children to ultrafine particles.

    Science.gov (United States)

    Buonanno, G; Marini, S; Morawska, L; Fuoco, F C

    2012-11-01

    Time-activity patterns and the airborne pollutant concentrations encountered by children each day are an important determinant of individual exposure to airborne particles. This is demonstrated in this work by using hand-held devices to measure the real-time individual exposure of more than 100 children aged 8-11 years to particle number concentrations and average particle diameter, as well as alveolar and tracheobronchial deposited surface area concentration. A GPS-logger and activity diaries were also used to give explanation to the measurement results. Children were divided in three sample groups: two groups comprised of urban schools (school time from 8:30 am to 1:30 pm) with lunch and dinner at home, and the third group of a rural school with only dinner at home. The mean individual exposure to particle number concentration was found to differ between the three groups, ranging from 6.2 × 10(4)part.cm(-3) for children attending one urban school to 1.6 × 10(4)part.cm(-3) for the rural school. The corresponding daily alveolar deposited surface area dose varied from about 1.7 × 10(3)mm(2) for urban schools to 6.0 × 10(2)mm(2) for the rural school. For all of the children monitored, the lowest particle number concentrations are found during sleeping time and the highest were found during eating time. With regard to alveolar deposited surface area dose, a child's home was the major contributor (about 70%), with school contributing about 17% for urban schools and 27% for the rural school. An important contribution arises from the cooking/eating time spent at home, which accounted for approximately 20% of overall exposure, corresponding to more than 200 mm(2). These activities represent the highest dose received per time unit, with very high values also encountered by children with a fireplace at home, as well as those that spend considerable time stuck in traffic jams. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Performance assessment of adding Cu-ultrafine particles into falling film desiccant

    International Nuclear Information System (INIS)

    Al-Mulla Ali, A.

    2006-01-01

    The concept of dehumidification between air and liquid desiccant for the improvement of the efficiency of heating and cooling fluids in industrial applications was discussed. The use of solid/liquid desiccants has received much attention in recent years because liquid desiccants can take moisture from surrounding air at low temperature and then release the moisture at high temperature to provide a continuous process of dehumidification of air and regeneration of liquid desiccant. This process can be used with conventional vapor compression cycles. This paper presented a comparative numerical study between parallel and counter flow configurations that examined the effects of various parameters on heat and mass transfer for the dehumidification and cooling processes of air and regeneration rate of liquid desiccant. Ultrafine particles were added to the falling film desiccant to investigate heat and mass transfer enhancement for both parallel and counter flow channels. The Cu-volume fraction in the falling film desiccant and dispersion effect were the important parameters. A mathematical model was therefore developed to account for the addition of Cu-ultrafine particles into the film desiccant. The dehumidification and cooling rate processes were found to improve with an increase in the Cu-ultrafine particles and dispersion effect. The new hybrid AC system was shown to improve indoor air quality, reduce energy consumption, and be environmentally safe. It was concluded that although the volume fraction and dispersion factor improve the dehumidification and cooling processes of the air, the improvements are not significant due to the small thickness of the falling-film desiccant. The regeneration process did not improve for either controlling parameter because of the small thickness of the film desiccant. 14 refs., 10 figs

  16. On the unification of aircraft ultrafine particle emission data

    Energy Technology Data Exchange (ETDEWEB)

    Kaercher, B.; Busen, R. [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Wessling (Germany). Inst. fuer Physik der Atmosphaere; Turco, R.P.; Yu Fangqun [California Univ., Los Angeles, CA (United States). Dept. of Atmospheric Sciences; Danilin, M.Y.; Weisenstein, D.K. [Atmospheric and Environmental Research, Inc., Cambridge, MA (United States); Miake-Lye, R.C. [Aerodyne Research, Inc., Billerica, MA (United States)

    2000-03-01

    To predict the environmental impacts of future commercial aviation, intensive studies have been launched to measure the properties and effects of aircraft emissions. These observations have revealed an extremely wide variance with respect to the number and sizes of the particles produced in the exhaust plumes. Aircraft aerosol ultimately contributes to the population of cloud-forming nuclei, and may lead to significant global radiative and chemical perturbations. In this paper, recent discoveries are coordinated and unified in the form of a physically consistent plume aerosol model that explains most of the observational variance. Using this new approach, it is now practical to carry out reliable global atmospheric simulations of aircraft effects, as demonstrated by a novel assessment of the perturbation of the stratospheric aerosol layer by a supersonic aircraft fleet. (orig.)

  17. Characterizing the spatial distribution of ambient ultrafine particles in Toronto, Canada: A land use regression model.

    Science.gov (United States)

    Weichenthal, Scott; Van Ryswyk, Keith; Goldstein, Alon; Shekarrizfard, Maryam; Hatzopoulou, Marianne

    2016-01-01

    Exposure models are needed to evaluate the chronic health effects of ambient ultrafine particles (bus routes as well as variables for the number of on-street trees, parks, open space, and the length of bus routes within a 100 m buffer. There was no systematic difference between measured and predicted values when the model was evaluated in an external dataset, although the R(2) value decreased (R(2) = 50%). This model will be used to evaluate the chronic health effects of UFPs using population-based cohorts in the Toronto area. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  18. Exposure to ultrafine particles, intracellular production of reactive oxygen species in leukocytes and altered levels of endothelial progenitor cells

    DEFF Research Database (Denmark)

    Jantzen, Kim; Møller, Peter Horn; Karottki, Dorina Gabriela

    2016-01-01

    . Additionally, the early endothelial progenitor cell levels were positively associated with a personalised measure of ultrafine particle exposure and negatively associated with both basal and capacity for reactive oxygen species production in lymphocytes and granulocytes, respectively. Our results indicate......Exposure to particles in the fine and ultrafine size range has been linked to induction of low-grade systemic inflammation, oxidative stress and development of cardiovascular diseases. Declining levels of endothelial progenitor cells within systemic circulation have likewise been linked...... to progression of cardiovascular diseases. The objective was to determine if exposure to fine and ultrafine particles from indoor and outdoor sources, assessed by personal and residential indoor monitoring, is associated with altered levels of endothelial progenitor cells, and whether such effects are related...

  19. Contribution of various microenvironments to the daily personal exposure to ultrafine particles

    DEFF Research Database (Denmark)

    Bekö, Gabriel; Kjeldsen, Birthe Uldahl; Olsen, Yulia

    2015-01-01

    a backpack equipped with a portable monitor, continuously recording particle number concentrations (PN), in order to measure the real-time individual exposure over a period of similar to 48 h. A GPS logger was carried along with the particle monitor and allowed us to estimate the contribution of UFP exposure......, compared to the GPS. These results may indicate limitations of using diaries, but also possible inaccuracy and miss-classification in the GPS data. (C) 2015 Elsevier Ltd. All rights reserved.......Exposure to ultrafine particles (UFP) may have adverse health effects. Central monitoring stations do not represent the personal exposure to UFP accurately. Few studies have previously focused on personal exposure to UFP. Sixty non-smoking residents living in Copenhagen, Denmark were asked to carry...

  20. Ultrafine particles

    DEFF Research Database (Denmark)

    Bekö, Gabriel; Weschler, Charles J.; Wierzbicka, Aneta

    2013-01-01

    .3 × 105 cm-3·h/day). On average, ∼90% of this exposure occurred outside of the period from midnight to 6 a.m. Source events, especially candle burning, cooking, toasting, and unknown activities, were responsible on average for ∼65% of the residential integrated exposure (51% without the unknown activities...

  1. Ultrafine Particles from Traffic Emissions and Children’s Health (UPTECH in Brisbane, Queensland (Australia: Study Design and Implementation

    Directory of Open Access Journals (Sweden)

    Wafaa Nabil Ezz

    2015-02-01

    Full Text Available Ultrafine particles are particles that are less than 0.1 micrometres (µm in diameter. Due to their very small size they can penetrate deep into the lungs, and potentially cause more damage than larger particles. The Ultrafine Particles from Traffic Emissions and Children’s Health (UPTECH study is the first Australian epidemiological study to assess the health effects of ultrafine particles on children’s health in general and peripheral airways in particular. The study is being conducted in Brisbane, Australia. Continuous indoor and outdoor air pollution monitoring was conducted within each of the twenty five participating school campuses to measure particulate matter, including in the ultrafine size range, and gases. Respiratory health effects were evaluated by conducting the following tests on participating children at each school: spirometry, forced oscillation technique (FOT and multiple breath nitrogen washout test (MBNW (to assess airway function, fraction of exhaled nitric oxide (FeNO, to assess airway inflammation, blood cotinine levels (to assess exposure to second-hand tobacco smoke, and serum C-reactive protein (CRP levels (to measure systemic inflammation. A pilot study was conducted prior to commencing the main study to assess the feasibility and reliably of measurement of some of the clinical tests that have been proposed for the main study. Air pollutant exposure measurements were not included in the pilot study.

  2. Occupational exposure to ultrafine particles among airport employees--combining personal monitoring and global positioning system

    DEFF Research Database (Denmark)

    Møller, Karina Lauenborg; Thygesen, Lau Caspar; Schipperijn, Jasper

    2014-01-01

    BACKGROUND: Exposure to ultrafine particles (UFP) has been linked to cardiovascular and lung diseases. Combustion of jet fuel and diesel powered handling equipment emit UFP resulting in potentially high exposure levels among employees working at airports. High levels of UFP have been reported...... at several airports, especially on the apron, but knowledge on individual exposure profiles among different occupational groups working at an airport is lacking. PURPOSE: The aim of this study was to compare personal exposure to UFP among five different occupational groups working at Copenhagen Airport (CPH......). METHOD: 30 employees from five different occupational groups (baggage handlers, catering drivers, cleaning staff and airside and landside security) at CPH were instructed to wear a personal monitor of particle number concentration in real time and a GPS device. The measurements were carried out on 8 days...

  3. Personal exposure to airborne ultrafine particles in the urban area of Milan

    International Nuclear Information System (INIS)

    Cattaneo, A; Garramone, G; Taronna, M; Peruzzo, C; Cavallo, D M

    2009-01-01

    The relevance of health effects related to ultrafine particles (UFPs; aerodynamic diameter 5 particles/cm 3 . UFPs measures were divided on the basis of crossed environments or micro-environments, days of the week and day time (hours). The highest measured mean concentrations and data variability were observed during walking time and moving on motorized vehicles (bus and car), indicating that the highest exposure to UFPs can be reached near motorized traffic. The lowest exposures were observed in green areas and in office microenvironments. An appreciable difference between working and non-working days was observed. Concentration patterns and variation by days of the week and time periods appears related to time trends in traffic intensity.

  4. Exposure to ultrafine particles in hospitality venues with partial smoking bans.

    Science.gov (United States)

    Neuberger, Manfred; Moshammer, Hanns; Schietz, Armin

    2013-01-01

    Fine particles in hospitality venues with insufficient smoking bans indicate health risks from passive smoking. In a random sample of Viennese inns (restaurants, cafes, bars, pubs and discotheques) effects of partial smoking bans on indoor air quality were examined by measurement of count, size and chargeable surface of ultrafine particles (UFPs) sized 10-300 nm, simultaneously with mass of particles sized 300-2500 nm (PM2.5). Air samples were taken in 134 rooms unannounced during busy hours and analyzed by a diffusion size classifier and an optical particle counter. Highest number concentrations of particles were found in smoking venues and smoking rooms (median 66,011 pt/cm(3)). Even non-smoking rooms adjacent to smoking rooms were highly contaminated (median 25,973 pt/cm(3)), compared with non-smoking venues (median 7408 pt/cm(3)). The particle number concentration was significantly correlated with the fine particle mass (Phospitality premises. Health protection of non-smoking guests and employees from risky UFP concentration is insufficient, even in rooms labeled "non-smoking". Partial smoking bans with separation of smoking rooms failed.

  5. Physicochemical characteristics and occupational exposure to coarse, fine and ultrafine particles during building refurbishment activities

    Energy Technology Data Exchange (ETDEWEB)

    Azarmi, Farhad; Kumar, Prashant, E-mail: p.kumar@surrey.ac.uk, E-mail: prashant.kumar@cantab.net; Mulheron, Mike [University of Surrey, Department of Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences (United Kingdom); Colaux, Julien L.; Jeynes, Chris [University of Surrey, Faculty of Engineering and Physical Sciences, Ion Beam Centre (United Kingdom); Adhami, Siavash; Watts, John F. [University of Surrey, The Surface Analysis Laboratory, Faculty of Engineering and Physical Sciences (United Kingdom)

    2015-08-15

    Understanding of the emissions of coarse (PM{sub 10} ≤10 μm), fine (PM{sub 2.5} ≤2.5 μm) and ultrafine particles (UFP <100 nm) from refurbishment activities and their dispersion into the nearby environment is of primary importance for developing efficient risk assessment and management strategies in the construction and demolition industry. This study investigates the release, occupational exposure and physicochemical properties of particulate matter, including UFPs, from over 20 different refurbishment activities occurring at an operational building site. Particles were measured in the 5–10,000-nm-size range using a fast response differential mobility spectrometer and a GRIMM particle spectrometer for 55 h over 8 days. The UFPs were found to account for >90 % of the total particle number concentrations and <10 % of the total mass concentrations released during the recorded activities. The highest UFP concentrations were 4860, 740, 650 and 500 times above the background value during wall-chasing, drilling, cementing and general demolition activities, respectively. Scanning electron microscopy, X-ray photoelectron spectroscopy and ion beam analysis were used to identify physicochemical characteristics of particles and attribute them to probable sources considering the size and the nature of the particles. The results confirm that refurbishment activities produce significant levels (both number and mass) of airborne particles, indicating a need to develop appropriate regulations for the control of occupational exposure of operatives undertaking building refurbishment.

  6. Soot, unburned carbon and ultrafine particle emissions from air- and oxy-coal flames

    International Nuclear Information System (INIS)

    Morris, W.J.; Yu, Dunxi; Wendt, J.O.L.

    2010-01-01

    Oxy-coal combustion is one possible solution for the mitigation of greenhouse gases. In this process coal is burned in oxygen, rather than air, and the temperatures in the boiler are mitigated by recycling flue gases, so that the inlet mixture may contain either 27 % O 2 to match adiabatic flame temperatures, or 32 % O 2 to match gaseous radiation heat fluxes in the combustion chamber. However, a major issue for heat transfer from coal combustion is the radiative heat transmission from soot. For this research, air and oxy coal firing were compared regarding the emission of soot. A 100 kW down-fired laboratory combustor was used to determine effects of switching from air to oxy-firing on soot, unburned carbon and ultrafine particle emissions from practical pulverized coal flames. Of interest here were potential chemical effects of substitution of the N 2 in air by CO 2 in practical pulverized coal flames. The oxy-coal configuration investigated used once-through CO 2 , simulating cleaned flue gas recycle with all contaminants and water removed. Three coals were each burned in: a) air, b) 27 % O 2 / 73 % CO 2 , c) 32 % O 2 / 68 % CO 2 . Tests were conducted at (nominally) 3 %, 2 %, 1 % and 0 % O 2 in the exhaust (dry basis). For each condition, particulate samples were iso kinetically withdrawn far from the radiant zone, and analyzed using a photoacoustic analyzer (PA) for black carbon, a scanning mobility particle sizer (SMPS) for ultrafine particles, and a total sample loss on ignition (LOI) method for unburned carbon in ash. Data suggest that at low stoichiometric ratios, ultrafine particles consist primarily of black carbon, which, for the bituminous coal, is produced in lesser amounts under oxy-fired conditions than under the air-fired condition, even when adiabatic flame temperatures are matched. However, significant changes in mineral matter vaporization were not observed unless the flames were hotter. These and other results are interpreted in the light of

  7. SEPARATION OF FISCHER-TROPSCH WAX PRODUCTS FROM ULTRAFINE IRON CATALYST PARTICLES

    Energy Technology Data Exchange (ETDEWEB)

    James K. Neathery; Gary Jacobs; Burtron H. Davis

    2004-03-31

    In this reporting period, a fundamental filtration study was started to investigate the separation of Fischer-Tropsch Synthesis (FTS) liquids from iron-based catalyst particles. Slurry-phase FTS in slurry bubble column reactor systems is the preferred mode of production since the reaction is highly exothermic. Consequently, heavy wax products must be separated from catalyst particles before being removed from the reactor system. Achieving an efficient wax product separation from iron-based catalysts is one of the most challenging technical problems associated with slurry-phase FTS. The separation problem is further compounded by catalyst particle attrition and the formation of ultra-fine iron carbide and/or carbon particles. Existing pilot-scale equipment was modified to include a filtration test apparatus. After undergoing an extensive plant shakedown period, filtration tests with cross-flow filter modules using simulant FTS wax slurry were conducted. The focus of these early tests was to find adequate mixtures of polyethylene wax to simulate FTS wax. Catalyst particle size analysis techniques were also developed. Initial analyses of the slurry and filter permeate particles will be used by the research team to design improved filter media and cleaning strategies.

  8. Ultrafine particles dispersion modeling in a street canyon: development and evaluation of a composite lattice Boltzmann model.

    Science.gov (United States)

    Habilomatis, George; Chaloulakou, Archontoula

    2013-10-01

    Recently, a branch of particulate matter research concerns on ultrafine particles found in the urban environment, which originate, to a significant extent, from traffic sources. In urban street canyons, dispersion of ultrafine particles affects pedestrian's short term exposure and resident's long term exposure as well. The aim of the present work is the development and the evaluation of a composite lattice Boltzmann model to study the dispersion of ultrafine particles, in urban street canyon microenvironment. The proposed model has the potential to penetrate into the physics of this complex system. In order to evaluate the model performance against suitable experimental data, ultrafine particles levels have been monitored on an hourly basis for a period of 35 days, in a street canyon, in Athens area. The results of the comparative analysis are quite satisfactory. Furthermore, our modeled results are in a good agreement with the results of other computational and experimental studies. This work is a first attempt to study the dispersion of an air pollutant by application of the lattice Boltzmann method. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Ultrafine and fine particle formation in a naturally ventilated office as a result of reactions between ozone and scented products

    DEFF Research Database (Denmark)

    Toftum, Jørn; Dijken, F. v.

    2003-01-01

    Ultrafine and fine particle formation as a result of chemical reactions between ozone and four different air fresheners and a typical lemon-scented domestic cleaner was studied in a fully furnished, naturally ventilated office. The study showed that under conditions representative of those...

  10. Variability in exposure to ambient ultrafine particles in urban schools: Comparative assessment between Australia and Spain.

    Science.gov (United States)

    Mazaheri, Mandana; Reche, Cristina; Rivas, Ioar; Crilley, Leigh R; Álvarez-Pedrerol, Mar; Viana, Mar; Tobias, Aurelio; Alastuey, Andrés; Sunyer, Jordi; Querol, Xavier; Morawska, Lidia

    2016-03-01

    Ambient ultrafine particle number concentrations (PNC) have inhomogeneous spatio-temporal distributions and depend on a number of different urban factors, including background conditions and distant sources. This paper quantitatively compares exposure to ambient ultrafine particles at urban schools in two cities in developed countries, with high insolation climatic conditions, namely Brisbane (Australia) and Barcelona (Spain). The analysis used comprehensive indoor and outdoor air quality measurements at 25 schools in Brisbane and 39 schools in Barcelona. PNC modes were analysed with respect to ambient temperature, land use and urban characteristics, combined with the measured elemental carbon concentrations, NOx (Brisbane) and NO2 (Barcelona). The trends and modes of the quantified weekday average daily cycles of ambient PNC exhibited significant differences between the two cities. PNC increases were observed during traffic rush hours in both cases. However, the mid-day peak was dominant in Brisbane schools and had the highest contribution to total PNC for both indoors and outdoors. In Barcelona, the contribution from traffic was highest for ambient PNC, while the mid-day peak had a slightly higher contribution for indoor concentrations. Analysis of the relationships between PNC and land use characteristics in Barcelona schools showed a moderate correlation with the percentage of road network area and an anti-correlation with the percentage of green area. No statistically significant correlations were found for Brisbane. Overall, despite many similarities between the two cities, school-based exposure patterns were different. The main source of ambient PNC at schools was shown to be traffic in Barcelona and mid-day new particle formation in Brisbane. The mid-day PNC peak in Brisbane could have been driven by the combined effect of background and meteorological conditions, as well as other local/distant sources. The results have implications for urban development

  11. Exposure to ultrafine particles, intracellular production of reactive oxygen species in leukocytes and altered levels of endothelial progenitor cells

    International Nuclear Information System (INIS)

    Jantzen, Kim; Møller, Peter; Karottki, Dorina Gabriela; Olsen, Yulia; Bekö, Gabriel; Clausen, Geo; Hersoug, Lars-Georg; Loft, Steffen

    2016-01-01

    Exposure to particles in the fine and ultrafine size range has been linked to induction of low-grade systemic inflammation, oxidative stress and development of cardiovascular diseases. Declining levels of endothelial progenitor cells within systemic circulation have likewise been linked to progression of cardiovascular diseases. The objective was to determine if exposure to fine and ultrafine particles from indoor and outdoor sources, assessed by personal and residential indoor monitoring, is associated with altered levels of endothelial progenitor cells, and whether such effects are related to leukocyte-mediated oxidative stress. The study utilized a cross sectional design performed in 58 study participants from a larger cohort. Levels of circulating endothelial progenitor cells, defined as either late (CD34 + KDR + cells) or early (CD34 + CD133 + KDR + cells) subsets were measured using polychromatic flow cytometry. We additionally measured production of reactive oxygen species in leukocyte subsets (lymphocytes, monocytes and granulocytes) by flow cytometry using intracellular 2′,7′-dichlorofluoroscein. The measurements encompassed both basal levels of reactive oxygen species production and capacity for reactive oxygen species production for each leukocyte subset. We found that the late endothelial progenitor subset was negatively associated with levels of ultrafine particles measured within the participant residences and with reactive oxygen species production capacity in lymphocytes. Additionally, the early endothelial progenitor cell levels were positively associated with a personalised measure of ultrafine particle exposure and negatively associated with both basal and capacity for reactive oxygen species production in lymphocytes and granulocytes, respectively. Our results indicate that exposure to fine and ultrafine particles derived from indoor sources may have adverse effects on human vascular health.

  12. White-light Detection for Nanoparticle Sizing with the TSI Ultrafine Condensation Particle Counter

    International Nuclear Information System (INIS)

    Dick, William D.; McMurry, Peter H.; Weber, Rodney J.; Quant, Frederick R.

    2000-01-01

    Several of the most common methods for measuring nanoparticle size distributions employ the ultrafine condensation particle counter (UCPC) for detection purposes. Among these methods, the pulse height analysis (PHA) technique, in which the optical response of the UCPC detector is related to initial particle diameter in the 3-10 nm range, prevails in applications where fast sampling is required or for which concentrations of nanoparticles are frequently very low. With the PHA technique, white light is required for particle illumination in order to obtain a monotonic relationship between initial particle diameter and optical response (pulse height). However, the popular, commercially available TSI Model 3025A UCPC employs a laser for particle detection. Here, we report on a novel white-light detection system developed for the 3025A UCPC that involves minimal alteration to the instrument and preserves normal counting operation. Performance is illustrated with pulse height spectra produced by differential mobility analyzer (DMA) - generated calibration aerosols in the 3-50 nm range

  13. NANODERM. Quality of skin as a barrier to ultra-fine particles

    International Nuclear Information System (INIS)

    Kiss, A.Z.; Kertesz, Zs.; Szikszai, Z.; Biro, T.; Czifra, G.; Toth, B.I.; Juhasz, I.; Kiss, B.; Hunyadi, J.

    2007-01-01

    Complete text of publication follows. The EU5 project carried out by a consortium of 12 European universities and research institutes under the leadership of the Faculty of Physics and Geosciences, University of Leipzig started in 2003 and ended with the publication of its final report in 2007. The main goal of the project was to get quantitative information on the penetration of ultra-fine particles in all strata of skin, on their penetration pathways as well as on their impact on human health. Details of the project can be found on the following website: http://www.uni-leipzig.de/"~nanoderm. The Hungarian team was lead by the Department of Dermatology, University of Debrecen, who provided human skin grafted on SCID (Severe Combined Immune Deficiency) mice as a suitable model for studying particle penetration. In the Institute of Physiology, University of Debrecen, the cellular effects of the nanoparticles were assessed. The ATOMKI group performed ion beam analytical investigations using proton induced x-ray emission and scanning transmission ion microscopy techniques to determine the particle distribution on porcine, SCID graft and human skin samples on which various nanoparticle (TiO 2 ) formulations including commercially available sunscreens were applied. Several pre-treatments of the skin were tested, too. The skin samples were cryofixed native specimens, reducing considerably the possibility of creating artefacts. Results Titanium was only detected in the stratum corneum for healthy skin. Penetration to layers consisting of living cells was not observed. No diffusion profile was present therefore we conclude that the penetration takes place through mechanical action. Deep penetration into hair follicles was also observed, but not into vital tissue. Clearance is expected via desquamation and sebum excretion respectively for corneocyte layers and hair follicles. In conclusion, the NANODERM group does not expect any harmful effects of sunscreens containing

  14. Synthesis and electrochemistry properties of Sn-Sb ultrafine particles as anode of lithium-ion batteries

    International Nuclear Information System (INIS)

    Wang, Zhong; Tian, Wenhuai; Li, Xingguo

    2007-01-01

    Ultrafine particles of Sn-Sb alloys with different chemical composition have been prepared by hydrogen plasma-metal reaction. Structure, morphology, size and chemical composition of the Sn-Sb ultrafine particles were investigated by transmission electron microscopy, X-ray diffraction, BET gas adsorption, and induction-coupled plasma spectroscopy. It was found that all the particles have spherical shapes, with average particle size in the range of 100-300 nm. The electrochemistry properties as an alternative anode material for lithium-ion batteries have been characterized by constant current cycling and cyclic voltammetry. Electrochemical measurements showed that the alloys with Sn-46.5 at.% Sb have best reversible capacity and capacity retention. It exhibited a high reversible lithium-ion storage capacity of 701 mAh g -1 in the initial cycle, which has remained at 81% (i.e., 566 mAh g -1 ) of its original capacity after 20 cycles

  15. Measurements of ultrafine particles from a gas-turbine burning biofuels

    Energy Technology Data Exchange (ETDEWEB)

    Allouis, C.; Beretta, F.; Minutolo, P.; Pagliara, R. [Istituto di Ricerche sulla Combustione, CNR, Piazzale V. Tecchio, 80, 80125 Napoli (Italy); Sirignano, M.; Sgro, L.A.; D' Anna, A. [Dipartimento di Ingegneria Chimica, Universita di Napoli Federico II, Piazzale V. Tecchio, 80, 80125 Napoli (Italy)

    2010-04-15

    Measurements of ultrafine particles have been performed at the exhaust of a low emission microturbine for power generation. This device has been fuelled with liquid fuels, including a commercial diesel oil, a mixture of the diesel oil with a biodiesel and kerosene, and tested under different loads. Primarily attention has been focused on the measurements of the size distribution functions of the particles emitted from the system by using particle differential mobility analysis. A bimodal size distribution function of the particle emitted has been found in all the examined conditions. Burning diesel oil, the first mode of the size distribution function of the combustion-formed particles is centered at around 2-3 nm, whereas the second mode is centered at about 20-30 nm. The increase of the turbine load and the addition of 50% of biodiesel has not caused changes in the shape of size distribution of the particles. A slightly decrease of the amount of particle formed has been found. By using kerosene the amount of emitted particles increases of more than one order of magnitude. Also the shape of the size distribution function changes with the first mode shifted towards larger particles of the order of 8-10 nm but with a lower emission of larger 20-30 nm particles. Overall, in this conditions, the mass concentration of particles is increased respect to the diesel oil operation. Particle sizes measured with the diesel oil have been compared with the results on a diesel engine operated in the same power conditions and with the same fuel. Measurements have showed that the mean sizes of the formed particles do not change in the two combustion systems. However, diesel engine emits a number concentration of particles more than two orders of magnitude higher in the same conditions of power and with the same fuel. By running the engine in more premixed-like conditions, the size distribution function of the particles approaches that measured by burning kerosene in the

  16. Using the Aerasense NanoTracer for simultaneously obtaining several ultrafine particle exposure metrics

    International Nuclear Information System (INIS)

    Marra, J

    2011-01-01

    The expanding production and use of nanomaterials increases the chance of human exposure to engineered nanoparticles (NP), also referred to as ultrafine particles (UFP; ≤ 100 - 300 nm). This is particularly true in workplaces where they can become airborne and thereafter inhaled by workers during nanopowder processing. Considering the suspected hazard of many engineered UFPs, the general recommendation is to take measures for minimizing personal exposure while monitoring the UFP pollution for assessment and control purposes. The portable Aerasense NanoTracer accomplishes this UFP monitoring, either intermittently or in real time. This paper reviews its design and operational characteristics and elaborates on a number of application extensions and constraints. The NanoTracer's output signals enable several UFP exposure metrics to be simultaneously inferred. These include the airborne UFP number concentration and the number-averaged particle size, serving as characteristics of the pertaining UFP pollution. When non-hygroscopic particles are involved, the NanoTracer's output signals also allow an estimation of the lung-deposited UFP surface area concentration and the lung-deposited UFP mass concentration. It is thereby possible to distinguish between UFP depositions in the alveolar region, the trachea-bronchial region and the head airway region, respectively, by making use of the ICRP particle deposition model.

  17. Performance of school bus retrofit systems: ultrafine particles and other vehicular pollutants.

    Science.gov (United States)

    Zhang, Qunfang; Zhu, Yifang

    2011-08-01

    This study evaluated the performance of retrofit systems for diesel-powered school buses, a diesel oxidation catalyst (DOC) muffler and a spiracle crankcase filtration system (CFS), regarding ultrafine particles (UFPs) and other air pollutants from tailpipe emissions and inside bus cabins. Tailpipe emissions and in-cabin air pollutant levels were measured before and after retrofitting when the buses were idling and during actual pick-up/drop off routes. Retrofit systems significantly reduced tailpipe emissions with a reduction of 20-94% of total particles with both DOC and CFS installed. However, no unequivocal decrease was observed for in-cabin air pollutants after retrofitting. The AC/fan unit and the surrounding air pollutant concentrations played more important roles for determining the in-cabin air quality of school buses than did retrofit technologies. Although current retrofit systems reduce children's exposure while waiting to board at a bus station, retrofitting by itself does not protect children satisfactorily from in-cabin particle exposures. Turning on the bus engine increased in-cabin UFP levels significantly only when the wind blew from the bus' tailpipe toward its hood with its windows open. This indicated that wind direction and window position are significant factors determining how much self-released tailpipe emissions may penetrate into the bus cabin. The use of an air purifier was found to remove in-cabin particles by up to 50% which might be an alternative short-to-medium term strategy to protect children's health.

  18. Reduced Ultrafine Particle Concentration in Urban Air: Changes in Nucleation and Anthropogenic Emissions.

    Science.gov (United States)

    Saha, Provat K; Robinson, Ellis S; Shah, Rishabh U; Zimmerman, Naomi; Apte, Joshua S; Robinson, Allen L; Presto, Albert A

    2018-06-19

    Nucleation is an important source of ambient ultrafine particles (UFP). We present observational evidence of the changes in the frequency and intensity of nucleation events in urban air by analyzing long-term particle size distribution measurements at an urban background site in Pittsburgh, Pennsylvania during 2001-2002 and 2016-2017. We find that both frequency and intensity of nucleation events have been reduced by 40-50% over the past 15 years, resulting in a 70% reduction in UFP concentrations from nucleation. On average, the particle growth rates are 30% slower than 15 years ago. We attribute these changes to dramatic reductions in SO 2 (more than 90%) and other pollutant concentrations. Overall, UFP concentrations in Pittsburgh have been reduced by ∼48% in the past 15 years, with a ∼70% reduction in nucleation, ∼27% in weekday local sources (e.g., weekday traffic), and 49% in the regional background. Our results highlight that a reduction in anthropogenic emissions can considerably reduce nucleation events and UFP concentrations in a polluted urban environment.

  19. Combustion of PTFE: The Effects of Gravity and Pigmentation on Ultrafine Particle Generation

    Science.gov (United States)

    McKinnon, J. Thomas; Srivastava, Rajiv; Todd, Paul

    1997-01-01

    Ultrafine particles generated during polymer thermodegradation are a major health hazard, owing to their unique pathway of processing in the lung. This hazard in manned spacecraft is poorly understood, because the particulate products of polymer thermodegradation are generated under low gravity conditions. Particulate generated from the degradation of PolyTetraFluoroEthylene (PTFE), insulation coating for 20 AWG copper wire (representative of spacecraft application) under intense ohmic heating were studied in terrestrial gravity and microgravity. Microgravity tests were done in a 1.2-second drop tower at the Colorado School of Mines (CSM). Thermophoretic sampling was used for particulate collection. Transmission Electron Microscopy (TEM) and Scanning Transmission Electron Microscopy (STEM) were used to examine the smoke particulates. Image software was used to calculate particle size distribution. In addition to gravity, the color of PTFE insulation has an overwhelming effect on size, shape and morphology of the particulate. Nanometer-sized primary particles were found in all cases, and aggregation and size distribution was dependent on both color and gravity; higher aggregation occurred in low gravity. Particulates from white, black, red and yellow colored PTFE insulations were studied. Elemental analysis of the particulates shows the presence of inorganic pigments.

  20. Alterations in welding process voltage affect the generation of ultrafine particles, fume composition, and pulmonary toxicity.

    Science.gov (United States)

    Antonini, James M; Keane, Michael; Chen, Bean T; Stone, Samuel; Roberts, Jenny R; Schwegler-Berry, Diane; Andrews, Ronnee N; Frazer, David G; Sriram, Krishnan

    2011-12-01

    The goal was to determine if increasing welding voltage changes the physico-chemical properties of the fume and influences lung responses. Rats inhaled 40 mg/m³ (3 h/day × 3 days) of stainless steel (SS) welding fume generated at a standard voltage setting of 25 V (regular SS) or at a higher voltage (high voltage SS) of 30 V. Particle morphology, size and composition were characterized. Bronchoalveolar lavage was performed at different times after exposures to assess lung injury. Fumes collected from either of the welding conditions appeared as chain-like agglomerates of nanometer-sized primary particles. High voltage SS welding produced a greater number of ultrafine-sized particles. Fume generated by high voltage SS welding was higher in manganese. Pulmonary toxicity was more substantial and persisted longer after exposure to the regular SS fume. In summary, a modest raise in welding voltage affected fume size and elemental composition and altered the temporal lung toxicity profile.

  1. Unhealthy diet and ultrafine carbon black particles induce senescence and disease associated phenotypic changes.

    Science.gov (United States)

    Büchner, Nicole; Ale-Agha, Niloofar; Jakob, Sascha; Sydlik, Ulrich; Kunze, Kerstin; Unfried, Klaus; Altschmied, Joachim; Haendeler, Judith

    2013-01-01

    Diet and pollution are environmental factors known to compromise "healthy aging" of the cardiovascular and respiratory systems. The molecular consequences of this permanent burden in these cells are still unknown. Therefore, this study investigates the impact of unhealthy diet on aging-related signaling pathways of human, primary cardiovascular cells and of airborne particles on lung epithelial and human endothelial cells. Nutrition health reports have shown that the diet in industrialized countries contains more than 100mg/dl low density lipoprotein (LDL) and a high fraction of added sugars, especially fructose. Several studies demonstrated that ultrafine particles can enter the circulation and thus may interact with endothelial cells directly. Both, dietary compounds and pollution derived particles, have been shown to increase the risk for cardiovascular diseases. To simulate an unhealthy diet, we supplemented cell culture media of human primary endothelial cells, smooth muscle cells and cardiomyocytes with LDL and replaced 1/3 of glucose with fructose. We observed hypertrophy in cardiomyocytes, enhanced proliferation in smooth muscle cells and increased senescence, loss of endothelial nitric oxide synthase and increased nuclear FoxO3A in endothelial cells. With respect to pollution we have used ultrafine carbon black particles (ufCB), one of the major constituents of industrial and exhaust emissions, in concentrations our lungs and vessels are constantly exposed to. These concentrations of ufCB increased reactive oxygen species in lung epithelial and vascular endothelial cells and reduced the S-NO content, a marker for NO-bioavailability, in endothelial cells. NO increases activation of Telomerase Reverse Transcriptase (TERT), an enzyme essential for telomere maintenance. TERT is required for proper endothelial cell function and is inactivated by Src kinase under conditions of oxidative stress. ufCB significantly increased Src kinase activation and reduced

  2. Impact of superplasticizer concentration and of ultra-fine particles on the rheological behaviour of dense mortar suspensions

    International Nuclear Information System (INIS)

    Artelt, C.; Garcia, E.

    2008-01-01

    This work aims at investigating the impact of the addition of superplasticizer and of ultra-fine particles, namely of silica fume and of precipitated titania, on the rheological behaviour of water-lean mortar pastes. The pastes are characterised in terms of their spread, their flowing behaviour and by means of performing a shear test, giving access to viscosity/shear gradient correlations. Adding superplasticizer is shown to shift the onset of shear thickening of the referring pastes to higher shear rates and to attenuate its otherwise rapid evolution, possibly by means of favouring steric particle-particle interactions. The workability of these mortars, which is characterised in terms of spread values and draining, is also improved. For the case of fly ash based mortars, adding ultra-fine particles is another way of (slightly) 'retarding' shear thickening and of attenuating its evolution, possibly because of resulting in - on the average - lower hydrodynamic forces and reduced attractive Van der Waals interactions between particles. However, at the same time these mortars are characterised by a worsening in workability which is attributed to the huge amount of surface area provided by the ultra-fines

  3. Air pollutant concentrations near three Texas roadways, Part I: Ultrafine particles

    Science.gov (United States)

    Zhu, Yifang; Pudota, Jayanth; Collins, Donald; Allen, David; Clements, Andrea; DenBleyker, Allison; Fraser, Matt; Jia, Yuling; McDonald-Buller, Elena; Michel, Edward

    Vehicular emitted air pollutant concentrations were studied near three types of roadways in Austin, Texas: (1) State Highway 71 (SH-71), a heavily traveled arterial highway dominated by passenger vehicles; (2) Interstate 35 (I-35), a limited access highway north of Austin in Georgetown; and (3) Farm to Market Road 973 (FM-973), a heavily traveled surface roadway dominated by truck traffic. Air pollutants examined include carbon monoxide (CO), oxides of nitrogen (NO x), and carbonyl species in the gas-phase. In the particle phase, ultrafine particle (UFP) concentrations (diameter road were found to be the most important factors determining UFP concentrations near the roadways. Since wind directions were not consistent during the sampling periods, distances along wind trajectories from the roadway to the sampling points were used to study the decay characteristics of UFPs. Under perpendicular wind conditions, for all studied roadway types, particle number concentrations increased dramatically moving from the upwind side to the downwind side. The elevated particle number concentrations decay exponentially with increasing distances from the roadway with sharp concentration gradients observed within 100-150 m, similar to previously reported studies. A single exponential decay curve was found to fit the data collected from all three roadways very well under perpendicular wind conditions. No consistent pattern was observed for UFPs under parallel wind conditions. However, regardless of wind conditions, particle concentrations returned to background levels within a few hundred meters of the roadway. Within measured UFP size ranges, smaller particles (6-25 nm) decayed faster than larger ones (100-300 nm). Similar decay rates were observed among UFP number, surface, and volume.

  4. On the spatial distribution and evolution of ultrafine particles in Barcelona

    Directory of Open Access Journals (Sweden)

    M. Dall'Osto

    2013-01-01

    Full Text Available Sources and evolution of ultrafine particles were investigated both horizontally and vertically in the large urban agglomerate of Barcelona, Spain. Within the SAPUSS project (Solving Aerosol Problems by Using Synergistic Strategies, a large number of instruments was deployed simultaneously at different monitoring sites (road, two urban background, regional background, urban tower 150 m a.s.l., urban background tower site 80 m a.s.l. during a 4 week period in September–October 2010. Particle number concentrations (N>5 nm are highly correlated with black carbon (BC at all sites only under strong vehicular traffic influences. By contrast, under cleaner atmospheric conditions (low condensation sink, CS such correlation diverges towards much higher N/BC ratios at all sites, indicating additional sources of particles including secondary production of freshly nucleated particles. Size-resolved aerosol distributions (N10–500 as well as particle number concentrations (N>5 nm allow us to identify three types of nucleation and growth events: (1 a regional type event originating in the whole study region and impacting almost simultaneously the urban city of Barcelona and the surrounding urban background area; (2 a regional type event impacting only the regional background area but not the urban agglomerate; (3 an urban type event which originates only within the city centre but whose growth continues while transported away from the city to the regional background. Furthermore, during these clean air days, higher N are found at tower level than at ground level only in the city centre whereas such a difference is not so pronounced at the remote urban background tower. In other words, this study suggests that the column of air above the city ground level possesses the optimal combination between low CS and high vapour source, hence enhancing the concentrations of freshly nucleated

  5. Exposure to carbon monoxide, fine particle mass, and ultrafine particle number in Jakarta, Indonesia: effect of commute mode.

    Science.gov (United States)

    Both, Adam F; Westerdahl, Dane; Fruin, Scott; Haryanto, Budi; Marshall, Julian D

    2013-01-15

    We measured real-time exposure to PM(2.5), ultrafine PM (particle number) and carbon monoxide (CO) for commuting workers school children, and traffic police, in Jakarta, Indonesia. In total, we measured exposures for 36 individuals covering 93 days. Commuters in private cars experienced mean (st dev) exposures of 22 (9.4) ppm CO, 91 (38) μg/m(3)PM(2.5), and 290 (150)×10(3) particles cm(-3). Mean concentrations were higher in public transport than in private cars for PM(2.5) (difference in means: 22%) and particle counts (54%), but not CO, likely reflecting in-vehicle particle losses in private cars owing to air-conditioning. However, average commute times were longer for private car commuters than public transport commuters (in our sample, 24% longer: 3.0 vs. 2.3 h per day). Commute and traffic-related exposures experienced by Jakarta residents are among the highest in the world, owing to high on-road concentrations and multi-hour commutes. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Environmental and health impacts of fine and ultrafine metallic particles: Assessment of threat scores

    Energy Technology Data Exchange (ETDEWEB)

    Goix, Sylvaine [Université de Toulouse, INP-ENSAT, Av. Agrobiopôle, 31326 Castanet-Tolosan (France); UMR 5245 CNRS-INP-UPS, EcoLab (Laboratoire d' écologie fonctionnelle), Avenue de l' Agrobiopôle, BP 32607, 31326 Castanet-Tolosan (France); Lévêque, Thibaut [Université de Toulouse, INP-ENSAT, Av. Agrobiopôle, 31326 Castanet-Tolosan (France); UMR 5245 CNRS-INP-UPS, EcoLab (Laboratoire d' écologie fonctionnelle), Avenue de l' Agrobiopôle, BP 32607, 31326 Castanet-Tolosan (France); ADEME (French Agency for Environment and Energy Management), 20 Avenue du Grésillé, BP 90406, 49004 Angers Cedex 01 (France); Xiong, Tian-Tian [Université de Toulouse, INP-ENSAT, Av. Agrobiopôle, 31326 Castanet-Tolosan (France); UMR 5245 CNRS-INP-UPS, EcoLab (Laboratoire d' écologie fonctionnelle), Avenue de l' Agrobiopôle, BP 32607, 31326 Castanet-Tolosan (France); Schreck, Eva [Géosciences Environnement Toulouse (GET), Observatoire Midi Pyrénées, Université de Toulouse, CNRS, IRD, 14 Avenue E. Belin, F-31400 Toulouse (France); and others

    2014-08-15

    This study proposes global threat scores to prioritize the harmfulness of anthropogenic fine and ultrafine metallic particles (FMP) emitted into the atmosphere at the global scale. (Eco)toxicity of physicochemically characterized FMP oxides for metals currently observed in the atmosphere (CdO, CuO, PbO, PbSO{sub 4}, Sb{sub 2}O{sub 3}, and ZnO) was assessed by performing complementary in vitro tests: ecotoxicity, human bioaccessibility, cytotoxicity, and oxidative potential. Using an innovative methodology based on the combination of (eco)toxicity and physicochemical results, the following hazard classification of the particles is proposed: CdCl{sub 2}∼CdO>CuO>PbO>ZnO>PbSO{sub 4}>Sb{sub 2}O{sub 3}. Both cadmium compounds exhibited the highest threat score due to their high cytotoxicity and bioaccessible dose, whatever their solubility and speciation, suggesting that cadmium toxicity is due to its chemical form rather than its physical form. In contrast, the Sb{sub 2}O{sub 3} threat score was the lowest due to particles with low specific area and solubility, with no effects except a slight oxidative stress. As FMP physicochemical properties reveal differences in specific area, crystallization systems, dissolution process, and speciation, various mechanisms may influence their biological impact. Finally, this newly developed and global approach could be widely used in various contexts of pollution by complex metal particles and may improve risk management. - Highlights: • Seven micro- and nano- monometallic characterized particles were studied as references. • Bioaccessibility, eco and cytotoxicity, and oxidative potential assays were performed. • According to calculated threat scores: CdCl{sub 2}∼CdO>CuO>PbO>ZnO>PbSO{sub 4}>Sb{sub 2}O{sub 3}.

  7. Ultrafine particles from diesel engines induce vascular oxidative stress via JNK activation.

    Science.gov (United States)

    Li, Rongsong; Ning, Zhi; Cui, Jeffery; Khalsa, Bhavraj; Ai, Lisong; Takabe, Wakako; Beebe, Tyler; Majumdar, Rohit; Sioutas, Constantinos; Hsiai, Tzung

    2009-03-15

    Exposure to particulate air pollution is linked to increased incidences of cardiovascular diseases. Ambient ultrafine particles (UFP) from diesel vehicle engines have been shown to be proatherogenic in ApoE knockout mice and may constitute a major cardiovascular risk in humans. We posited that circulating nano-sized particles from traffic pollution sources induce vascular oxidative stress via JNK activation in endothelial cells. Diesel UFP were collected from a 1998 Kenworth truck. Intracellular superoxide assay revealed that these UFP dose-dependently induced superoxide (O(2)(-)) production in human aortic endothelial cells (HAEC). Flow cytometry showed that UFP increased MitoSOX red intensity specific for mitochondrial superoxide. Protein carbonyl content was increased by UFP as an indication of vascular oxidative stress. UFP also up-regulated heme oxygenase-1 (HO-1) and tissue factor (TF) mRNA expression, and pretreatment with the antioxidant N-acetylcysteine significantly decreased their expression. Furthermore, UFP transiently activated JNK in HAEC. Treatment with the JNK inhibitor SP600125 and silencing of both JNK1 and JNK2 with siRNA inhibited UFP-stimulated O(2)(-) production and mRNA expression of HO-1 and TF. Our findings suggest that JNK activation plays an important role in UFP-induced oxidative stress and stress response gene expression.

  8. Assessing and reducing fine and ultrafine particles inside Los Angeles taxis

    Science.gov (United States)

    Yu, Nu; Shu, Shi; Lin, Yan; Zhu, Yifang

    2018-05-01

    Taxi drivers and passengers are exposed to high levels of traffic-related air pollutants, but their exposures to fine (PM2.5) and ultrafine particles (UFPs) and related mitigation strategies are rarely explored. In this study, UFP and PM2.5 concentrations were monitored concurrently inside and outside of 22 taxis under different ventilation and mitigation conditions. Under realistic working conditions (no mitigation; NM), the average UFP and PM2.5 levels inside taxis were 1.46 × 104 particles/cm3 and 26 μg/m3, respectively. When the taxi ventilation was set to outside air mode and the windows kept closed, in-cabin UFP and PM2.5 concentrations are significantly associated with on-road concentrations, driving speed, and cabin air filter usage. The average in-cabin to on-roadway (I/O) ratios for UFP and PM2.5 were reduced from 0.60 to 0.75 under NM, to 0.47 and 0.52 under the most stringent mitigation strategy of keeping the windows closed and operating a high efficiency cabin air filter (WC + HECA). Among all tested taxi models, Toyota Prius exhibited the lowest UFP and PM2.5 I/O ratios under WC + HECA. Switching cabin air filters from the originally equipped manufacturer filter (OEM) to a HECA filter reduced the UFP and PM2.5 I/O ratios most effectively in Toyota Prius taxis as well.

  9. Exposure assessment of a cyclist to PM10 and ultrafine particles.

    Science.gov (United States)

    Berghmans, P; Bleux, N; Int Panis, L; Mishra, V K; Torfs, R; Van Poppel, M

    2009-02-01

    Estimating personal exposure to air pollution is a crucial component in identifying high-risk populations and situations. It will enable policy makers to determine efficient control strategies. Cycling is again becoming a favorite mode of transport both in developing and in developed countries due to increasing traffic congestion and environmental concerns. In Europe, it is also seen as a healthy sports activity. However, due to high levels of hazardous pollutants in the present day road microenvironment the cyclist might be at a higher health risk due to higher breathing rate and proximity to the vehicular exhaust. In this paper we present estimates of the exposure of a cyclist to particles of various size fractions including ultrafine particles (UFP) in the town of Mol (Flanders, Belgium). The results indicate relatively higher UFP concentration exposure during morning office hours and moderate UFP levels during afternoon. The major sources of UFP and PM(10) were identified, which are vehicular emission and construction activities, respectively. We also present a dust mapping technique which can be a useful tool for town planners and local policy makers.

  10. Estimate of main local sources to ambient ultrafine particle number concentrations in an urban area

    Science.gov (United States)

    Rahman, Md Mahmudur; Mazaheri, Mandana; Clifford, Sam; Morawska, Lidia

    2017-09-01

    Quantifying and apportioning the contribution of a range of sources to ultrafine particles (UFPs, D oil refineries, and seaport) sources to the total ambient particle number concentration (PNC) in a busy, inner-city area in Brisbane, Australia using Bayesian statistical modelling and other exploratory tools. The Bayesian model was trained on the PNC data on days where NP formations were known to have not occurred, hourly traffic counts, solar radiation data, and smooth daily trend. The model was applied to apportion and quantify the contribution of NP formations and local traffic and non-traffic sources to UFPs. The data analysis incorporated long-term measured time-series of total PNC (D ≥ 6 nm), particle number size distributions (PSD, D = 8 to 400 nm), PM2.5, PM10, NOx, CO, meteorological parameters and traffic counts at a stationary monitoring site. The developed Bayesian model showed reliable predictive performances in quantifying the contribution of NP formation events to UFPs (up to 4 × 104 particles cm- 3), with a significant day to day variability. The model identified potential NP formation and no-formations days based on PNC data and quantified the sources contribution to UFPs. Exploratory statistical analyses show that total mean PNC during the middle of the day was up to 32% higher than during peak morning and evening traffic periods, which were associated with NP formation events. The majority of UFPs measured during the peak traffic and NP formation periods were between 30-100 nm and smaller than 30 nm, respectively. To date, this is the first application of Bayesian model to apportion different sources contribution to UFPs, and therefore the importance of this study is not only in its modelling outcomes but in demonstrating the applicability and advantages of this statistical approach to air pollution studies.

  11. Measurements of ultrafine particles and other vehicular pollutants inside school buses in South Texas

    Science.gov (United States)

    Zhang, Qunfang; Zhu, Yifang

    2010-01-01

    Increasing evidence has demonstrated toxic effects of vehicular emitted ultrafine particles (UFPs, diameter pollutants, especially UFPs, was measured inside four diesel-powered school buses. Two 1990 and two 2006 model year diesel-powered school buses were selected to represent the age extremes of school buses in service. Each bus was driven on two routine bus runs to study school children's exposure under different transportation conditions in South Texas. The number concentration and size distribution of UFPs, total particle number concentration, PM 2.5, PM 10, black carbon (BC), CO, and CO 2 levels were monitored inside the buses. The average total particle number concentrations observed inside the school buses ranged from 7.3 × 10 3 to 3.4 × 10 4 particles cm -3, depending on engine age and window position. When the windows were closed, the in-cabin air pollutants were more likely due to the school buses' self-pollution. The 1990 model year school buses demonstrated much higher air pollutant concentrations than the 2006 model year ones. When the windows were open, the majority of in-cabin air pollutants came from the outside roadway environment with similar pollutant levels observed regardless of engine ages. The highest average UFP concentration was observed at a bus transfer station where approximately 27 idling school buses were queued to load or unload students. Starting-up and idling generated higher air pollutant levels than the driving state. Higher in-cabin air pollutant concentrations were observed when more students were on board.

  12. Identification and verification of ultrafine particle affinity zones in urban neighbourhoods: sample design and data pre-processing.

    LENUS (Irish Health Repository)

    Harris, Paul

    2009-01-01

    A methodology is presented and validated through which long-term fixed site air quality measurements are used to characterise and remove temporal signals in sample-based measurements which have good spatial coverage but poor temporal resolution. The work has been carried out specifically to provide a spatial dataset of atmospheric ultrafine particle (UFP < 100 nm) data for ongoing epidemiologic cohort analysis but the method is readily transferable to wider epidemiologic investigations and research into the health effects of other pollutant species.

  13. Ultrafine particles are not major carriers of carcinogenic PAHs and their genotoxicity in size-segregated aerosols

    Czech Academy of Sciences Publication Activity Database

    Topinka, Jan; Milcová, Alena; Schmuczerová, Jana; Kroužek, J.; Hovorka, J.

    2013-01-01

    Roč. 754, 1-2 (2013), s. 1-6 ISSN 1383-5718 R&D Projects: GA ČR(CZ) GAP503/11/0142; GA ČR(CZ) GBP503/12/G147 Grant - others:MZP(CZ) SP/1A3/149/08 Institutional support: RVO:68378041 Keywords : Air pollution * Ultrafine particles * Carcinogenic PAHs Subject RIV: DN - Health Impact of the Environment Quality Impact factor: 2.481, year: 2013

  14. Preparation of a ceramic superconductor from ultrafine particles by freeze-dry process in Ba-Y-Cu-O system

    International Nuclear Information System (INIS)

    Chen Zuyao; Qian Yitai; Wan Yanjian; Rong Jingfang; Zhang Han; Pan Guoqiang; Zhao Yong; Zhang Qirui

    1989-01-01

    Freeze-dry technique is first reported for preparing ceramic ultrafines. The single-phase complex oxide Ba 2 YCu 3 O/sub 9-δ/, a poly-crystallized compound, and ceramic superconductor have been synthesized successfully. The experimental results show that not only is the ceramic superconductor obtained uniform with fine particles and excellent superconductivity, but the conditions for solid reactions are relatively limited

  15. Internal Combustion Engines as the Main Source of Ultrafine Particles in Residential Neighborhoods: Field Measurements in the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Štolcpartová, Jitka; Pechout, M.; Dittrich, L.; Mazač, M.; Fenkl, M.; Vrbová, Kristýna; Ondráček, Jakub; Vojtíšek-Lom, M.

    2015-01-01

    Roč. 6, č. 11 (2015), s. 1714-1735 ISSN 2073-4433 R&D Projects: GA ČR(CZ) GBP503/12/G147; GA ČR(CZ) GA13-01438S Institutional support: RVO:68378041 ; RVO:67985858 Keywords : ultrafine particles * nanoparticles * UFP Subject RIV: DN - Health Impact of the Environment Quality; DI - Air Pollution ; Quality (UCHP-M) Impact factor: 1.221, year: 2015

  16. Expert elicitation on ultrafine particles: likelihood of health effects and causal pathways

    Directory of Open Access Journals (Sweden)

    Brunekreef Bert

    2009-07-01

    Full Text Available Abstract Background Exposure to fine ambient particulate matter (PM has consistently been associated with increased morbidity and mortality. The relationship between exposure to ultrafine particles (UFP and health effects is less firmly established. If UFP cause health effects independently from coarser fractions, this could affect health impact assessment of air pollution, which would possibly lead to alternative policy options to be considered to reduce the disease burden of PM. Therefore, we organized an expert elicitation workshop to assess the evidence for a causal relationship between exposure to UFP and health endpoints. Methods An expert elicitation on the health effects of ambient ultrafine particle exposure was carried out, focusing on: 1 the likelihood of causal relationships with key health endpoints, and 2 the likelihood of potential causal pathways for cardiac events. Based on a systematic peer-nomination procedure, fourteen European experts (epidemiologists, toxicologists and clinicians were selected, of whom twelve attended. They were provided with a briefing book containing key literature. After a group discussion, individual expert judgments in the form of ratings of the likelihood of causal relationships and pathways were obtained using a confidence scheme adapted from the one used by the Intergovernmental Panel on Climate Change. Results The likelihood of an independent causal relationship between increased short-term UFP exposure and increased all-cause mortality, hospital admissions for cardiovascular and respiratory diseases, aggravation of asthma symptoms and lung function decrements was rated medium to high by most experts. The likelihood for long-term UFP exposure to be causally related to all cause mortality, cardiovascular and respiratory morbidity and lung cancer was rated slightly lower, mostly medium. The experts rated the likelihood of each of the six identified possible causal pathways separately. Out of these

  17. Ultrafine titanium dioxide particles in the absence of photoactivation can induce oxidative damage to human bronchial epithelial cells

    International Nuclear Information System (INIS)

    Gurr, J.-R.; Wang, Alexander S.S.; Chen, C.-H.; Jan, K.-Y.

    2005-01-01

    Ultrafine titanium dioxide (TiO 2 ) particles have been shown to exhibit strong cytotoxicity when exposed to UVA radiation, but are regarded as a biocompatible material in the absence of photoactivation. In contrast to this concept, the present results indicate that anatase-sized (10 and 20 nm) TiO 2 particles in the absence of photoactivation induced oxidative DNA damage, lipid peroxidation, and micronuclei formation, and increased hydrogen peroxide and nitric oxide production in BEAS-2B cells, a human bronchial epithelial cell line. However, the treatment with anatase-sized (200 and >200 nm) particles did not induce oxidative stress in the absence of light irradiation; it seems that the smaller the particle, the easier it is for the particle to induce oxidative damage. The photocatalytic activity of the anatase form of TiO 2 was reported to be higher than that of the rutile form. In contrast to this notion, the present results indicate that rutile-sized 200 nm particles induced hydrogen peroxide and oxidative DNA damage in the absence of light but the anatase-sized 200 nm particles did not. In total darkness, a slightly higher level of oxidative DNA damage was also detected with treatment using an anatase-rutile mixture than with treatment using either the anatase or rutile forms alone. These results suggest that intratracheal instillation of ultrafine TiO 2 particles may cause an inflammatory response

  18. MEMS-based silicon cantilevers with integrated electrothermal heaters for airborne ultrafine particle sensing

    Science.gov (United States)

    Wasisto, Hutomo Suryo; Merzsch, Stephan; Waag, Andreas; Peiner, Erwin

    2013-05-01

    The development of low-cost and low-power MEMS-based cantilever sensors for possible application in hand-held airborne ultrafine particle monitors is described in this work. The proposed resonant sensors are realized by silicon bulk micromachining technology with electrothermal excitation, piezoresistive frequency readout, and electrostatic particle collection elements integrated and constructed in the same sensor fabrication process step of boron diffusion. Built-in heating resistor and full Wheatstone bridge are set close to the cantilever clamp end for effective excitation and sensing, respectively, of beam deflection. Meanwhile, the particle collection electrode is located at the cantilever free end. A 300 μm-thick, phosphorus-doped silicon bulk wafer is used instead of silicon-on-insulator (SOI) as the starting material for the sensors to reduce the fabrication costs. To etch and release the cantilevers from the substrate, inductively coupled plasma (ICP) cryogenic dry etching is utilized. By controlling the etching parameters (e.g., temperature, oxygen content, and duration), cantilever structures with thicknesses down to 10 - 20 μm are yielded. In the sensor characterization, the heating resistor is heated and generating thermal waves which induce thermal expansion and further cause mechanical bending strain in the out-of-plane direction. A resonant frequency of 114.08 +/- 0.04 kHz and a quality factor of 1302 +/- 267 are measured in air for a fabricated rectangular cantilever (500x100x13.5 μm3). Owing to its low power consumption of a few milliwatts, this electrothermal cantilever is suitable for replacing the current external piezoelectric stack actuator in the next generation of the miniaturized cantilever-based nanoparticle detector (CANTOR).

  19. A reflexing electron microwave amplifier for rf particle accelerator applications

    International Nuclear Information System (INIS)

    Fazio, M.V.; Hoeberling, R.F.

    1988-01-01

    The evolution of rf-accelerator technology toward high-power, high-current, low-emittance beams produces an ever-increasing demand for efficient, very high power microwave power sources. The present klystron technology has performed very well but is not expected to produce reliable gigawatt peak-power units in the 1- to 10-GHz regime. Further major advancements must involve other types of sources. The reflexing-electron class of sources can produce microwave powers at the gigawatt level and has demonstrated operation from 800-MHz to 40-GHz. The pulse length appears to be limited by diode closure, and reflexing-electron devices have been operated in a repetitively pulsed mode. A design is presented for a reflexing electron microwave amplifier that is frequency and phase locked. In this design, the generated microwave power can be efficiently coupled to one or several accelerator loads. Frequency and phase-locking capability may permit parallel-source operation for higher power. The low-frequency (500-MHz to 10-GHz) operation at very high power required by present and proposed microwave particle accelerators makes an amplifier, based on reflexing electron phenomena, a candidate for the development of new accelerator power sources. (author)

  20. Morphology of Nano and Micro Fiber Structures in Ultrafine Particles Filtration

    International Nuclear Information System (INIS)

    Kimmer, Dusan; Vincent, Ivo; Fenyk, Jan; Petras, David; Zatloukal, Martin; Sambaer, Wannes; Zdimal, Vladimir

    2011-01-01

    Selected procedures permitting to prepare homogeneous nanofibre structures of the desired morphology by employing a suitable combination of variables during the electrospinning process are presented. A comparison (at the same pressure drop) was made of filtration capabilities of planar polyurethane nanostructures formed exclusively by nanofibres, space polycarbonate nanostructures having bead spacers, structures formed by a combination of polymethyl methacrylate micro- and nanofibres and polypropylene meltblown microstructures, through which ultrafine particles of ammonium sulphate 20-400 nm in size were filtered. The structures studied were described using a new digital image analysis technique based on black and white images obtained by scanning electron microscopy. More voluminous structures modified with distance microspheres and having a greater thickness and mass per square area of the material, i.e. structures possessing better mechanical properties, demanded so much in nanostructures, enable preparation of filters having approximately the same free volume fraction as flat nanofibre filters but an increased effective fibre surface area, changed pore size morphology and, consequently, a higher filter quality.

  1. Determinants of spikes in ultrafine particle concentration whilst commuting by bus

    Science.gov (United States)

    Lim, Shanon; Dirks, Kim N.; Salmond, Jennifer A.; Xie, Shanju

    2015-07-01

    This paper examines concentration of ultrafine particles (UFPs) based on data collected using high-resolution UFP monitors whilst travelling by bus during rush hour along three different urban routes in Auckland, New Zealand. The factors influencing in-bus UFP concentration were assessed using a combination of spatial, statistical and GIS analysis techniques to determine both spatial and temporal variability. Results from 68 bus trips showed that concentrations varied more within a route than between on a given day, despite differences in urban morphology, land use and traffic densities between routes. A number of trips were characterised by periods of very rapid increases in UFPs (concentration 'spikes'), followed by slow declines. Trips which recorded at least one spike (an increase of greater than 10,000 pt/cm3) resulted in significantly higher mean concentrations. Spikes in UFPs were significantly more likely to occur when travelling at low speeds and when passengers were alighting and boarding at bus stops close to traffic light intersections.

  2. Magnetic characteristics of ultrafine Fe particles reduced from uniform iron oxide particles

    Science.gov (United States)

    Bridger, K.; Watts, J.; Tadros, M.; Xiao, Gang; Liou, S. H.; Chien, C. L.

    1987-04-01

    Uniform, cubic 0.05-μm iron oxide particles were formed by forced hydrolysis of ferric perchlorate. These particles were reduced to α-Fe by heating in hydrogen at temperatures between 300 and 500 °C. The effect of reduction temperature and various prereduction treatments on the microstructure of the iron particles will be discussed. Complete reduction to α-Fe was established by 57Fe Mössbauer spectroscopy and x-ray diffraction. Magnetic measurements on epoxy and polyurethane films containing these particles with various mass fractions gave coercivities as high as 1000 Oe. The relationship between the magnetic measurements and the microstructure will be discussed. Na2SiO3 is found to be the best coating material for the process of reducing iron oxide particles to iron.

  3. Frequent ultrafine particle formation and growth in Canadian Arctic marine and coastal environments

    Science.gov (United States)

    Collins, Douglas B.; Burkart, Julia; Chang, Rachel Y.-W.; Lizotte, Martine; Boivin-Rioux, Aude; Blais, Marjolaine; Mungall, Emma L.; Boyer, Matthew; Irish, Victoria E.; Massé, Guillaume; Kunkel, Daniel; Tremblay, Jean-Éric; Papakyriakou, Tim; Bertram, Allan K.; Bozem, Heiko; Gosselin, Michel; Levasseur, Maurice; Abbatt, Jonathan P. D.

    2017-11-01

    The source strength and capability of aerosol particles in the Arctic to act as cloud condensation nuclei have important implications for understanding the indirect aerosol-cloud effect within the polar climate system. It has been shown in several Arctic regions that ultrafine particle (UFP) formation and growth is a key contributor to aerosol number concentrations during the summer. This study uses aerosol number size distribution measurements from shipboard expeditions aboard the research icebreaker CCGS Amundsen in the summers of 2014 and 2016 throughout the Canadian Arctic to gain a deeper understanding of the drivers of UFP formation and growth within this marine boundary layer. UFP number concentrations (diameter > 4 nm) in the range of 101-104 cm-3 were observed during the two seasons, with concentrations greater than 103 cm-3 occurring more frequently in 2016. Higher concentrations in 2016 were associated with UFP formation and growth, with events occurring on 41 % of days, while events were only observed on 6 % of days in 2014. Assessment of relevant parameters for aerosol nucleation showed that the median condensation sink in this region was approximately 1.2 h-1 in 2016 and 2.2 h-1 in 2014, which lie at the lower end of ranges observed at even the most remote stations reported in the literature. Apparent growth rates of all observed events in both expeditions averaged 4.3 ± 4.1 nm h-1, in general agreement with other recent studies at similar latitudes. Higher solar radiation, lower cloud fractions, and lower sea ice concentrations combined with differences in the developmental stage and activity of marine microbial communities within the Canadian Arctic were documented and help explain differences between the aerosol measurements made during the 2014 and 2016 expeditions. These findings help to motivate further studies of biosphere-atmosphere interactions within the Arctic marine environment to explain the production of UFP and their growth to sizes

  4. Characterizing ultrafine particles and other air pollutants in and around school buses.

    Science.gov (United States)

    Zhu, Yifang; Zhang, Qunfang

    2014-03-01

    Increasing evidence has demonstrated toxic effects of ultrafine particles (UFP*, diameter emissions from idling school buses to air pollutant levels in and around school buses under different scenarios; 3. Retrofit tests to evaluate the performance of two retrofit systems, a diesel oxidation catalyst (DOC) muffler and a crankcase filtration system (CFS), on reducing tailpipe emissions and in-cabin air pollutant concentrations under idling and driving conditions; and 4. High efficiency particulate air (HEPA) filter air purifier tests to evaluate the effectiveness of in-cabin filtration. In total, 24 school buses were employed to cover a wide range of school buses commonly used in the United States. Real-time air quality measurements included particle number concentration (PNC), fine and UFP size distribution in the size range 7.6-289 nm, PM2.5 mass concentration, black carbon (BC) concentration, and carbon monoxide (CO) and carbon dioxide (CO2) concentrations. For in-cabin measurements, instruments were placed on a platform secured to the rear seats inside the school buses. For all other tests, a second set of instruments was deployed to simultaneously measure the ambient air pollutant levels. For tailpipe emission measurements, the exhaust was diluted and then measured by instruments identical to those used for the in-cabin measurements. The results show that when driving on roads, in-cabin PNC, fine and UFP size distribution, PM2.5, BC, and CO varied by engine age, window position, driving speed, driving route, and operating conditions. Emissions from idling school buses increased the PNC close to the tailpipe by a factor of up to 26.0. Under some circumstances, tailpipe emissions of idling school buses increased the in-cabin PNC by factors ranging from 1.2 to 5.8 in the 10-30 nm particle size range. Retrofit systems significantly reduced the tailpipe emissions of idling school buses. With both DOC and CFS installed, PNC in tailpipe emissions dropped by 20

  5. Concentration levels and source apportionment of ultrafine particles in road microenvironments

    Science.gov (United States)

    Argyropoulos, G.; Samara, C.; Voutsa, D.; Kouras, A.; Manoli, E.; Voliotis, A.; Tsakis, A.; Chasapidis, L.; Konstandopoulos, A.; Eleftheriadis, K.

    2016-03-01

    A mobile laboratory unit (MOBILAB) with on-board instrumentation (Scanning Mobility Particle Sizer, SMPS; Ambient NOx analyzer) was used to measure size-resolved particle number concentrations (PNCs) of quasi-ultrafine particles (UFPs, 9-372 nm), along with NOx, in road microenvironments. On-road measurements were carried out in and around a large Greek urban agglomeration, the Thessaloniki Metropolitan Area (TMA). Two 2-week measurement campaigns were conducted during the warm period of 2011 and the cold period of 2012. During each sampling campaign, MOBILAB was driven through a 5-day inner-city route and a second 5-day external route covering in total a wide range of districts (urban, urban background, industrial and residential), and road types (major and minor urban roads, freeways, arterial and interurban roads). All routes were conducted during working days, in morning and in afternoon hours under real-world traffic conditions. Spatial classification of MOBILAB measurements involved the assignment of measurement points to location bins defined by the aspect ratio of adjacent urban street canyons (USCs). Source apportionment was further carried out, by applying Positive Matrix Factorization (PMF) to particle size distribution data. Apportioned PMF factors were interpreted, by employing a two-step methodology, which involved (a) statistical association of PMF factor contributions with 12 h air-mass back-trajectories ending at the TMA during MOBILAB measurements, and (b) Multiple Linear Regression (MLR) using PMF factor contributions as the dependent variables, while relative humidity, solar radiation flux, and vehicle speed were used as the independent variables. The applied data analysis showed that low-speed cruise and high-load engine operation modes are the two dominant sources of UFPs in most of the road microenvironments in the TMA, with significant contributions from background photochemical processes during the warm period, explaining the reversed

  6. Exposure assessment in Beijing, China: biological agents, ultrafine particles, and lead.

    Science.gov (United States)

    Dong, Shuofei; Yao, Maosheng

    2010-11-01

    In this study, air samples were taken using a BioSampler and gelatin filters from six sites in Beijing: office, hospital, student dormitory, train station, subway, and a commercial street. Dust samples were also collected using a surface sampler from the same environments. Limulus amoebocyte lysate (LAL) and Glucatell assays were used to quantify sample endotoxin and (1,3)-β-d-glucan concentration levels, respectively. Enzyme-linked immunosorbent assay (ELISA) was used to measure the dust mite allergens (Der p 1 and Der f 1). Ultrafine particle and lead concentrations in these sampling sites were also measured using P-Trak and atomic absorption spectrometer, respectively. Analysis of variance (ANOVA) and linear regression analysis were used to analyze the concentration data. Higher culturable bacteria (12,639 CFU/m3) and fungi (1,806 CFU/m3) concentrations were observed for the train station and the subway system, respectively. For the rest of sampling sites, their concentrations were comparable to those found in western countries, ranging from 990 to 2,276 CFU/m3 for bacteria, and from 119 to 269 CFU/m3 for fungi. ANOVA analysis indicated that there were statistically significant differences between the culturable bacterial and fungal concentration levels obtained for different sites (p value=0.0001 and 0.0047). As for dust allergens, endotoxin, and (1,3)-β-D-glucan, their concentrations also seemed to be comparable to those found in the developed countries. Airborne allergen concentrations ranged from 16 to 68 ng/m3. The dust-borne allergen concentration was observed to range from 0.063 to 0.327 ng/mg. As for endotoxin, the highest airborne concentration of 25.24 ng/m3 was observed for the commercial street, and others ranged from 0.0427 to 0.1259 ng/m3. And dust-borne endotoxin concentration ranged from 58.83 to 6,427.4 ng/mg. For (1,3)-β-D-glucan, the airborne concentration ranged from 0.02 to 1.2 ng/m3. Linear regression analyses showed that there existed

  7. Measurements and predictors of on-road ultrafine particle concentrations and associated pollutants in Los Angeles

    Energy Technology Data Exchange (ETDEWEB)

    Fruin, S. [California Air Resources Board, Sacramento (United States); University of Southern California, Los Angeles (United States). Keck School of Medicine, Department of Preventive Medicine; Westerdahl, D.; Sax, T. [California Air Resources Board, Sacramento (United States); Sioutas, C. [University of Southern California, Los Angeles (United States). Civil and Environmental Engineering; Fine, P.M. [University of Southern California, Los Angeles (United States). Civil and Environmental Engineering; South Coast Air Quality Management District, Diamond Bar, CA (United States)

    2008-01-15

    Motor vehicles are the dominant source of oxides of nitrogen (NO{sub x}), particulate matter(PM), and certain air toxics (e.g., benzene, 1,3-butadiene) in urban areas. On roadways, motor vehicle-related pollutant concentrations are typically many times higher than ambient concentrations. Due to high air exchange rates typical of moving vehicles, this makes time spent in vehicles on roadways a major source of exposure. This paper presents on-road measurements for Los Angeles freeways and arterial roads taken from a zero-emission electric vehicle outfitted with real-time instruments. The objective was to characterize air pollutant concentrations on roadways and identify the factors associated with the highest concentrations. Our analysis demonstrated that on freeways, concentrations of ultrafine particles (UFPs), black carbon, nitric oxide, and PM-bound polycyclic aromatic hydrocarbons (PM-PAH) are generated primarily by diesel-powered vehicles, despite the relatively low fraction ({approx}6%) of diesel-powered vehicles on Los Angeles freeways. However, UFP concentrations on arterial roads appeared to be driven primarily by proximity to gasoline-powered vehicles undergoing hard accelerations. Concentrations were roughly one-third of those on freeways. By using a multiple regression model for the freeway measurements, we were able to explain 60-70% of the variability in concentrations of UFP, black carbon, nitric oxide, and PM-PAH using measures of diesel truck density and hour of day (as an indicator of wind speed). Freeway concentrations of these pollutants were also well correlated wth readily available annual average daily truck counts, potentially allowing improved population exposure estimates for epidemiology studies. Based on these roadway measurements and average driving time, it appears that 33-45% of total UFP exposure for Los Angeles residents occurs due to time spent traveling in vehicles. (author)

  8. Measurements and predictors of on-road ultrafine particle concentrations and associated pollutants in Los Angeles

    International Nuclear Information System (INIS)

    Fruin, S.; Sioutas, C.

    2008-01-01

    Motor vehicles are the dominant source of oxides of nitrogen (NO x ), particulate matter(PM), and certain air toxics (e.g., benzene, 1,3-butadiene) in urban areas. On roadways, motor vehicle-related pollutant concentrations are typically many times higher than ambient concentrations. Due to high air exchange rates typical of moving vehicles, this makes time spent in vehicles on roadways a major source of exposure. This paper presents on-road measurements for Los Angeles freeways and arterial roads taken from a zero-emission electric vehicle outfitted with real-time instruments. The objective was to characterize air pollutant concentrations on roadways and identify the factors associated with the highest concentrations. Our analysis demonstrated that on freeways, concentrations of ultrafine particles (UFPs), black carbon, nitric oxide, and PM-bound polycyclic aromatic hydrocarbons (PM-PAH) are generated primarily by diesel-powered vehicles, despite the relatively low fraction (∼6%) of diesel-powered vehicles on Los Angeles freeways. However, UFP concentrations on arterial roads appeared to be driven primarily by proximity to gasoline-powered vehicles undergoing hard accelerations. Concentrations were roughly one-third of those on freeways. By using a multiple regression model for the freeway measurements, we were able to explain 60-70% of the variability in concentrations of UFP, black carbon, nitric oxide, and PM-PAH using measures of diesel truck density and hour of day (as an indicator of wind speed). Freeway concentrations of these pollutants were also well correlated wth readily available annual average daily truck counts, potentially allowing improved population exposure estimates for epidemiology studies. Based on these roadway measurements and average driving time, it appears that 33-45% of total UFP exposure for Los Angeles residents occurs due to time spent traveling in vehicles. (author)

  9. Indoor particulate pollution in fitness centres with emphasis on ultrafine particles.

    Science.gov (United States)

    Slezakova, Klara; Peixoto, Cátia; Oliveira, Marta; Delerue-Matos, Cristina; Pereira, Maria do Carmo; Morais, Simone

    2018-02-01

    Fitness centres (FC) represent a unique indoor microenvironment. Exercising on regular basis provides countless health benefits and improves overall well-being, but if these facilities have poor indoor air quality, the respective exercisers might be subjected to some adverse risks. Considering the limited existent data, this work aimed to evaluate particulate pollution (PM 10, PM 2.5 , and ultrafine particles - UFP) in indoor air of FC and to estimate the respective risks for occupants (both staff and exercising subjects). Sampling was conducted during 40 consecutive days of May-June 2014 in general fitness areas, studios and classrooms (for group activities) of four different fitness centres (FC1-FC4) situated within Oporto metropolitan area, Portugal. The results showed that across the four FC, PM 10 ranged between 5 and 1080 μg m -3 with median concentrations (15-43 μg m -3 ) fulfilling the limit (50 μg m -3 ) of Portuguese legislation in all FC. PM 2.5 (medians 5-37 μg m -3 ; range 5-777 μg m -3 ) exceeded thresholds of 25 μg m -3 at some FC, indicating potential risks for the respective occupants; naturally ventilated FC exhibited significantly higher PM ranges (p exercising. These results indicate that even short-term physical activity (or more specifically its intensity) might strongly influence the daily inhalation dose. Finally, women exhibited 1.2 times higher UFPs intake than men thus suggesting the need for future gender-specific studies assessing UFP exposure. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Measurements and predictors of on-road ultrafine particle concentrations and associated pollutants in Los Angeles

    Science.gov (United States)

    Fruin, S.; Westerdahl, D.; Sax, T.; Sioutas, C.; Fine, P. M.

    Motor vehicles are the dominant source of oxides of nitrogen (NO x), particulate matter (PM), and certain air toxics (e.g., benzene, 1,3-butadiene) in urban areas. On roadways, motor vehicle-related pollutant concentrations are typically many times higher than ambient concentrations. Due to high air exchange rates typical of moving vehicles, this makes time spent in vehicles on roadways a major source of exposure. This paper presents on-road measurements for Los Angeles freeways and arterial roads taken from a zero-emission electric vehicle outfitted with real-time instruments. The objective was to characterize air pollutant concentrations on roadways and identify the factors associated with the highest concentrations. Our analysis demonstrated that on freeways, concentrations of ultrafine particles (UFPs), black carbon, nitric oxide, and PM-bound polycyclic aromatic hydrocarbons (PM-PAH) are generated primarily by diesel-powered vehicles, despite the relatively low fraction (˜6%) of diesel-powered vehicles on Los Angeles freeways. However, UFP concentrations on arterial roads appeared to be driven primarily by proximity to gasoline-powered vehicles undergoing hard accelerations. Concentrations were roughly one-third of those on freeways. By using a multiple regression model for the freeway measurements, we were able to explain 60-70% of the variability in concentrations of UFP, black carbon, nitric oxide, and PM-PAH using measures of diesel truck density and hour of day (as an indicator of wind speed). Freeway concentrations of these pollutants were also well correlated with readily available annual average daily truck counts, potentially allowing improved population exposure estimates for epidemiology studies. Based on these roadway measurements and average driving time, it appears that 33-45% of total UFP exposure for Los Angeles residents occurs due to time spent traveling in vehicles.

  11. Size distribution of chemical elements and their source apportionment in ambient coarse, fine, and ultrafine particles in Shanghai urban summer atmosphere.

    Science.gov (United States)

    Lü, Senlin; Zhang, Rui; Yao, Zhenkun; Yi, Fei; Ren, Jingjing; Wu, Minghong; Feng, Man; Wang, Qingyue

    2012-01-01

    Ambient coarse particles (diameter 1.8-10 microm), fine particles (diameter 0.1-1.8 microm), and ultrafine particles (diameter Source apportionment of the chemical elements was analyzed by means of an enrichment factor method. Our results showed that the average mass concentrations of coarse particles, fine particles and ultrafine particles in the summer air were 9.38 +/- 2.18, 8.82 +/- 3.52, and 2.02 +/- 0.41 microg/m3, respectively. The mass percentage of the fine particles accounted for 51.47% in the total mass of PM10, indicating that fine particles are the major component in the Shanghai ambient particles. SEM/EDX results showed that the coarse particles were dominated by minerals, fine particles by soot aggregates and fly ashes, and ultrafine particles by soot particles and unidentified particles. SRXRF results demonstrated that crustal elements were mainly distributed in the coarse particles, while heavy metals were in higher proportions in the fine particles. Source apportionment revealed that Si, K, Ca, Fe, Mn, Rb, and Sr were from crustal sources, and S, Cl, Cu, Zn, As, Se, Br, and Pb from anthropogenic sources. Levels of P, V, Cr, and Ni in particles might be contributed from multi-sources, and need further investigation.

  12. Technical solutions for reducing indoor residential exposures to ultrafine particles from second-hand cigarette smoke infiltration

    DEFF Research Database (Denmark)

    Afshari, Alireza; Ardkapan, Siamak Rahimi; Bergsøe, Niels Christian

    2011-01-01

    was carried out in the field in a multi-storey building and cardboard and plastic foil of polyethylene were used for sealing the entire wooden floor in the receiving flat. Another technical solution examined was a novel air circulating ductwork. The efficiency of the novel air circulating ductwork...... in which smoke infiltrates from one flat to another and also to examine technical solutions for preventing or reducing infiltration of ultrafine particles from the source flat to the receiving flat. One of the technical solutions examined was sealing of the floor in the receiving flat. The study...

  13. Reduced ultrafine particle levels in São Paulo's atmosphere during shifts from gasoline to ethanol use.

    Science.gov (United States)

    Salvo, Alberto; Brito, Joel; Artaxo, Paulo; Geiger, Franz M

    2017-07-18

    Despite ethanol's penetration into urban transportation, observational evidence quantifying the consequence for the atmospheric particulate burden during actual, not hypothetical, fuel-fleet shifts, has been lacking. Here we analyze aerosol, meteorological, traffic, and consumer behavior data and find, empirically, that ambient number concentrations of 7-100-nm diameter particles rise by one-third during the morning commute when higher ethanol prices induce 2 million drivers in the real-world megacity of São Paulo to substitute to gasoline use (95% confidence intervals: +4,154 to +13,272 cm -3 ). Similarly, concentrations fall when consumers return to ethanol. Changes in larger particle concentrations, including US-regulated PM2.5, are statistically indistinguishable from zero. The prospect of increased biofuel use and mounting evidence on ultrafines' health effects make our result acutely policy relevant, to be weighed against possible ozone increases. The finding motivates further studies in real-world environments. We innovate in using econometrics to quantify a key source of urban ultrafine particles.The biofuel ethanol has been introduced into urban transportation in many countries. Here, by measuring aerosols in São Paulo, the authors find that high ethanol prices coincided with an increase in harmful nanoparticles by a third, as drivers switched from ethanol to cheaper gasoline, showing a benefit of ethanol.

  14. Effect of shot peening using ultra-fine particles on fatigue properties of 5056 aluminum alloy under rotating bending

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Shoichi, E-mail: kikuchi@mech.kobe-u.ac.jp [Department of Mechanical Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe-shi, Hyogo 657-8501 (Japan); Nakamura, Yuki [Department of Mechanical Engineering, National Institute of Technology, Toyota College, 2-1 Eisei-cho, Toyota-shi, Aichi 471-8525 (Japan); Nambu, Koichiro [Department of Mechanical Engineering, National Institute of Technology, Suzuka College, Shiroko-cho, Suzuka-shi, Mie 510-0294 (Japan); Ando, Masafumi [Innovation Team, IKK SHOT Co. Ltd., 412-4, Nunowari, Minami-Shibata-machi, Tokai-shi, Aichi 476-0001 (Japan)

    2016-01-15

    Shot peening using particles 10 μm in diameter (ultra-fine particle peening: Ultra-FPP) was introduced to improve the fatigue properties of 5056 aluminum alloy. The surface microstructures of the Ultra-FPP treated specimens were characterized using a micro-Vickers hardness tester, scanning electron microscopy (SEM), X-ray diffraction (XRD), non-contact scanning white light interferometry, and electron backscatter diffraction (EBSD). The Ultra-FPP treated specimen had higher hardness than the conventional FPP treated specimen with a short nozzle distance due to the high velocity of the ultra-fine particles. Furthermore, the surface hardness of the Ultra-FPP treated specimen tended to increase as the peening time decreased. Fatigue tests were performed in air at room temperature using a cantilever-type rotating bending fatigue testing machine. It was found that the fatigue life of the Ultra-FPP treated specimen tended to increase with decreasing peening time. Mainly, the Ultra-FPP improved the fatigue properties of 5056 aluminum alloy in the very high cycle regime of more than 10{sup 7} cycles compared with the un-peened specimens. This is because the release of the compressive residual stress is small during fatigue tests at low stress amplitudes.

  15. Effects of ultrafine diesel exhaust particles on oxidative stress generation and dopamine metabolism in PC-12 cells.

    Science.gov (United States)

    Kim, Yong-Dae; Lantz-McPeak, Susan M; Ali, Syed F; Kleinman, Michael T; Choi, Young-Sook; Kim, Heon

    2014-05-01

    A major constituent of urban air pollution is diesel exhaust, a complex mixture of gases, chemicals, and particles. Recent evidence suggests that exposure to air pollution can increase the risk of a fatal stroke, cause cerebrovascular damage, and induce neuroinflammation and oxidative stress that may trigger neurodegenerative diseases, such as Parkinson's disease. The specific aim of this study was to determine whether ultrafine diesel exhaust particles (DEPs), the particle component of exhaust from diesel engines, can induce oxidative stress and effect dopamine metabolism in PC-12 cells. After 24 h exposure to DEPs of 200 nm or smaller, cell viability, ROS and nitric oxide (NO(2)) generation, and levels of dopamine (DA) and its metabolites, (dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA)), were evaluated. Results indicated cell viability was not significantly changed by DEP exposure. However, ROS showed dramatic dose-dependent changes after DEP exposure (2.4 fold increase compared to control at 200 μg/mL). NO(2) levels were also dose-dependently increased after DEP exposure. Although not in a dose-dependent manner, upon DEP exposure, intracellular DA levels were increased while DOPAC and HVA levels decreased when compared to control. Results suggest that ultrafine DEPs lead to dopamine accumulation in the cytoplasm of PC-12 cells, possibly contributing to ROS formation. Further studies are warranted to elucidate this mechanism. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

  16. Water-soluble ions in nano/ultrafine/fine/coarse particles collected near a busy road and at a rural site

    International Nuclear Information System (INIS)

    Lin, C.-C.; Chen, S.-J.; Huang, K.-L.; Lee, W.-J.; Lin, W.-Y.; Liao, C.-J.; Chaung, H.-C.; Chiu, C.-H.

    2007-01-01

    This study investigated water-soluble ions in the sized particles (particularly nano (PM 0.01-0.056 )/ultrafine (PM 0.01-0.1 )) collected using MOUDI and Nano-MOUDI samplers near a busy road site and at a rural site. The analytical results demonstrate that nano and coarse particles exhibited the highest (16.3%) and lowest (8.37%) nitrate mass ratios, respectively. The mass ratio of NO 3 - was higher than that of SO 4 2- in all the sized particles at the traffic site. The secondary aerosols all displayed trimodal distributions. The aerosols in ultrafine particles collected at the roadside site exhibited Aitken mode distributions indicating they were of local origin. This finding was not observed for those ultrafine particles collected at the rural site. The mass median diameters (MMDs) of the nano, ultrafine, and fine particles were smaller at the traffic site than at the rural site, possibly related to the contribution of mobile engine emissions. - NO 3 - > SO 4 2- in mass ratio, different from common observations in rural areas, was found in (particularly the nano) traffic-associated particles

  17. Activation of endothelial cells after exposure to ambient ultrafine particles: The role of NADPH oxidase

    International Nuclear Information System (INIS)

    Mo Yiqun; Wan Rong; Chien Sufan; Tollerud, David J.; Zhang Qunwei

    2009-01-01

    Several studies have shown that ultrafine particles (UFPs) may pass from the lungs to the circulation because of their very small diameter, and induce lung oxidative stress with a resultant increase in lung epithelial permeability. The direct effects of UFPs on vascular endothelium remain unknown. We hypothesized that exposure to UFPs leads to endothelial cell O 2 ·- generation via NADPH oxidase and results in activation of endothelial cells. Our results showed that UFPs, at a non-toxic dose, induced reactive oxygen species (ROS) generation in mouse pulmonary microvascular endothelial cells (MPMVEC) that was inhibited by pre-treatment with the ROS scavengers or inhibitors, but not with the mitochondrial inhibitor, rotenone. UFP-induced ROS generation in MPMVEC was abolished by p67 phox siRNA transfection and UFPs did not cause ROS generation in MPMVEC isolated from gp91 phox knock-out mice. UFP-induced ROS generation in endothelial cells was also determined in vivo by using a perfused lung model with imaging. Moreover, Western blot and immunofluorescence staining results showed that MPMVEC treated with UFPs resulted in the translocation of cytosolic proteins of NADPH oxidase, p47 phox , p67 phox and rac 1, to the plasma membrane. These results demonstrate that NADPH oxidase in the pulmonary endothelium is involved in ROS generation following exposure to UFPs. To investigate the activation of endothelial cells by UFP-induced oxidative stress, we determined the activation of the mitogen-activated protein kinases (MAPKs) in MPMVEC. Our results showed that exposure of MPMVEC to UFPs caused increased phosphorylation of p38 and ERK1/2 MAPKs that was blocked by pre-treatment with DPI or p67 phox siRNA. Exposure of MPMVEC obtained from gp91 phox knock-out mice to UFPs did not cause increased phosphorylation of p38 and ERK1/2 MAPKs. These findings confirm that UFPs can cause endothelial cells to generate ROS directly via activation of NADPH oxidase. UFP-induced ROS lead to

  18. Exposure to ultrafine particles in different transport modes in the city of Rome

    International Nuclear Information System (INIS)

    Grana, Mario; Toschi, Nicola; Vicentini, Laura; Pietroiusti, Antonio; Magrini, Andrea

    2017-01-01

    There is evidence of adverse health impacts from human exposure to particulate air pollution, including increased rates of respiratory and cardiovascular illness, hospitalizations, and pre-mature mortality. Most recent hypotheses assign an important role to ultrafine particles (UFP) (<0.1 μm) and to associated transition metals (in particular Fe). In a large city like Rome, where many active people spend more than one hour per day in private or public transportation, it may be important to evaluate the level of exposure to harmful pollutants which occurs during urban travelling. In this context, the aim of this work was to examine the relative contribution of different transport modes to total daily exposure. We performed experimental measurements during both morning and evening traffic peak hours throughout the winter season (December 2013–March 2014), for a total of 98 trips. Our results suggest that the lowest UFP exposures are experienced by underground train commuters, with an average number concentration of 14 134 cm −3 , and are largely a reflection of the routes being at greater distance from vehicular traffic. Motorcyclists experienced significantly higher average concentrations (73 168 cm −3 ) than all other exposure classes, and this is most likely a result of the presence of high-concentration and short-duration peaks which do not occur when the same routes are traveled by car. UFP concentrations in subway train environments were found to be comparable to urban background levels. Still, in underground trains we found the highest values of PM 10 mass concentration with a maximum value of 422 μg/m 3 . PM 10 concentration in trains was found to be four and two times higher than what was measured in car and motorbike trips, respectively. Transport mode contribution to total integrated UFP daily exposure was found to be 16.3%–20.9% while travelling by car, 28.7% for motorbike trips, and 8.7% for subway trips. Due to lower exposure times

  19. Response of spontaneously hypertensive rats to inhalation of fine and ultrafine particles from traffic: experimental controlled study

    Directory of Open Access Journals (Sweden)

    Dormans Jan AMA

    2006-05-01

    Full Text Available Abstract Background Many epidemiological studies have shown that mass concentrations of ambient particulate matter (PM are associated with adverse health effects in the human population. Since PM is still a very crude measure, this experimental study has explored the role of two distinct size fractions: ultrafine (3 to 3613 μg/m3 for fCAP and from 269μg/m3 to 556 μg/m3 for u+fCAP. Results Ammonium, nitrate, and sulphate ions accounted for 56 ± 16% of the total fCAP mass concentrations, but only 17 ± 6% of the u+fCAP mass concentrations. Unambiguous particle uptake in alveolar macrophages was only seen after u+fCAP exposures. Neither fCAP nor u+fCAP induced significant changes of cytotoxicity or inflammation in the lung. However, markers of oxidative stress (heme oxygenase-1 and malondialdehyde were affected by both fCAP and u+fCAP exposure, although not always significantly. Additional analysis revealed heme oxygenase-1 (HO-1 levels that followed a nonmonotonic function with an optimum at around 600 μg/m3 for fCAP. As a systemic response, exposure to u+fCAP and fCAP resulted in significant decreases of the white blood cell concentrations. Conclusion Minor pulmonary and systemic effects are observed after both fine and ultrafine + fine PM exposure. These effects do not linearly correlate with the CAP mass. A greater component of traffic CAP and/or a larger proportion ultrafine PM does not strengthen the absolute effects.

  20. Internal Combustion Engines as the Main Source of Ultrafine Particles in Residential Neighborhoods: Field Measurements in the Czech Republic

    Directory of Open Access Journals (Sweden)

    Jitka Stolcpartova

    2015-11-01

    Full Text Available Ultrafine particles (UFP, diameter < 100 nm exposure has already been associated with adverse effects on human health. Spatial distribution of UFP is non-uniform; they concentrate in the vicinity of the source, e.g. traffic, because of their short lifespan. This work investigates spatial distribution of UFP in three areas in the Czech Republic with different traffic load: High traffic (Prague neighborhood—Sporilov, commuter road vicinity (Libeznice, and a small city with only local traffic (Celakovice. Size-resolved measurements of particles in the 5–500 nm range were taken with a particle classifier mounted, along with batteries, GPS and other accessories, on a handcart and pushed around the areas, making one-minute or longer stops at places of interest. Concentrations along main roads were elevated in comparison with places farther from the road; this pattern was observed in all sites, while particle number distributions both close and away from main roads had similar patterns. The absence of larger particles, the relative absence of higher concentrations of particles away from the main roads, and similar number distributions suggest that high particle number concentrations cannot be readily attributed to sources other than internal combustion engines in vehicles and mobile machinery (i.e., mowers and construction machines.

  1. Coal emissions adverse human health effects associated with ultrafine/nano-particles role and resultant engineering controls.

    Science.gov (United States)

    Oliveira, Marcos L S; Navarro, Orlando G; Crissien, Tito J; Tutikian, Bernardo F; da Boit, Kátia; Teixeira, Elba C; Cabello, Juan J; Agudelo-Castañeda, Dayana M; Silva, Luis F O

    2017-10-01

    There are multiple elements which enable coal geochemistry: (1) boiler and pollution control system design parameters, (2) temperature of flue gas at collection point, (3) feed coal and also other fuels like petroleum coke, tires and biomass geochemistry and (4) fuel feed particle size distribution homogeneity distribution, maintenance of pulverisers, etc. Even though there is a large number of hazardous element pollutants in the coal-processing industry, investigations on micrometer and nanometer-sized particles including their aqueous colloids formation reactions and their behaviour entering the environment are relatively few in numbers. X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/ (Energy Dispersive Spectroscopy) EDS/ (selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM)/EDS and granulometric distribution analysis were used as an integrated characterization techniques tool box to determine both geochemistry and nanomineralogy for coal fly ashes (CFAs) from Brazil´s largest coal power plant. Ultrafine/nano-particles size distribution from coal combustion emissions was estimated during the tests. In addition the iron and silicon content was determined as 54.6% of the total 390 different particles observed by electron bean, results aimed that these two particles represent major minerals in the environment particles normally. These data may help in future investigations to asses human health actions related with nano-particles. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Measuring PM2.5, Ultrafine Particles, Nicotine Air and Wipe Samples Following the Use of Electronic Cigarettes.

    Science.gov (United States)

    Melstrom, Paul; Koszowski, Bartosz; Thanner, Meridith Hill; Hoh, Eunha; King, Brian; Bunnell, Rebecca; McAfee, Tim

    2017-09-01

    Few studies have examined the extent of inhalation or dermal contact among bystanders following short-term, secondhand e-cigarette exposure. Measure PM2.5 (particles e-cigarette exposure. E-cigarettes were used ad libitum by three experienced users for 2 hours during two separate sessions (disposable e-cigarettes, then tank-style e-cigarettes, or "tanks") in a 1858 ft3 room. We recorded: uncorrected PM2.5 (using SidePak); UF (using P-Trak); air nicotine concentrations (using air samplers; SKC XAD-4 canisters); ambient air exchange rate (using an air capture hood). Wipe samples were taken by wiping 100 cm2 room surfaces pre- and post- both sessions, and clean cloth wipes were worn during the exposure and collected at the end. Uncorrected PM2.5 and UF were higher (p e-cigarette use can produce: elevated PM2.5; elevated UF; nicotine in the air; and accumulation of nicotine on surfaces and clothing. Short-term indoor e-cigarette use produced accumulation of nicotine on surfaces and clothing, which could lead to dermal exposure to nicotine. Short-term e-cigarette use produced elevated PM2.5 and ultrafine particles, which could lead to secondhand inhalation of these particles and any chemicals associated with them by bystanders. We measured significant differences in PM2.5 and ultrafine particles between disposable e-cigarettes and tank-style e-cigarettes, suggesting a difference in the exposure profiles of e-cigarette products. Published by Oxford University Press on behalf of Society for Research on Nicotine and Tobacco 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.

  3. Relationships of outdoor and indoor ultrafine particles at residences downwind of a major international border crossing in Buffalo, NY.

    Science.gov (United States)

    McAuley, T R; Fisher, R; Zhou, X; Jaques, P A; Ferro, A R

    2010-08-01

    During winter 2006, indoor and outdoor ultrafine particle (UFP) size distribution measurements for particles with diameters from 5.6 to 165 nm were taken at five homes in a neighborhood directly adjacent to the Peace Bridge Complex (PBC), a major international border crossing connecting Buffalo, New York to Fort Erie, Ontario. Monitoring with 1-s time resolution was conducted for several hours at each home. Participants were instructed to keep all external windows and doors closed and to refrain from cooking, smoking, or other activity that may result in elevating the indoor UFP number concentration. Although the construction and age for the homes were similar, indoor-to-outdoor comparisons indicate that particle infiltration rates varied substantially. Overall, particle concentrations indoors were lower and less variable than particle concentrations outdoors, with average indoor-outdoor ratios ranging from 0.1 to 0.5 (mean 0.34) for particles between 5.6 and 165 nm in diameter. With no indoor sources, the average indoor-outdoor ratios were lowest (0.2) for 20-nm particles, higher (0.3) for particles <10 nm, and highest (0.5) for particles 70-165 nm. This study provides insight into the penetration of UFP into homes and the resulting change in particle size distributions as particles move indoors near a major diesel traffic source. Although people spend most of their time in their homes, exposure estimates for epidemiological studies are generally determined using ambient concentrations. The findings of this study will contribute to improved size-resolved UFP exposure estimates for near roadway exposure assessments and epidemiological studies.

  4. Influence of external mass transfer limitation on apparent kinetic parameters of penicillin G acylase immobilized on nonporous ultrafine silica particles.

    Science.gov (United States)

    Kheirolomoom, Azadeh; Khorasheh, Farhad; Fazelinia, Hossein

    2002-01-01

    Immobilization of enzymes on nonporous supports provides a suitable model for investigating the effect of external mass transfer limitation on the reaction rate in the absence of internal diffusional resistance. In this study, deacylation of penicillin G was investigated using penicillin acylase immobilized on ultrafine silica particles. Kinetic studies were performed within the low-substrate-concentration region, where the external mass transfer limitation becomes significant. To predict the apparent kinetic parameters and the overall effectiveness factor, knowledge of the external mass transfer coefficient, k(L)a, is necessary. Although various correlations exist for estimation of k(L)a, in this study, an optimization scheme was utilized to obtain this coefficient. Using the optimum values of k(L)a, the initial reaction rates were predicted and found to be in good agreement with the experimental data.

  5. Beyond PM2.5: The role of ultrafine particles on adverse health effects of air pollution.

    Science.gov (United States)

    Chen, Rui; Hu, Bin; Liu, Ying; Xu, Jianxun; Yang, Guosheng; Xu, Diandou; Chen, Chunying

    2016-12-01

    Air pollution constitutes the major threat to human health, whereas their adverse impacts and underlying mechanisms of different particular matters are not clearly defined. Ultrafine particles (UFPs) are high related to the anthropogenic emission sources, i.e. combustion engines and power plants. Their composition, source, typical characters, oxidative effects, potential exposure routes and health risks were thoroughly reviewed. UFPs play a major role in adverse impacts on human health and require further investigations in future toxicological research of air pollution. Unlike PM2.5, UFPs may have much more impacts on human health considering loads of evidences emerging from particulate matters and nanotoxicology research fields. The knowledge of nanotoxicology contributes to the understanding of toxicity mechanisms of airborne UFPs in air pollution. This article is part of a Special Issue entitled Air Pollution, edited by Wenjun Ding, Andrew J. Ghio and Weidong Wu. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Ultrafine particle emissions by in-use diesel buses of various generations at low-load regimes

    Science.gov (United States)

    Tartakovsky, L.; Baibikov, V.; Comte, P.; Czerwinski, J.; Mayer, A.; Veinblat, M.; Zimmerli, Y.

    2015-04-01

    Ultrafine particles (UFP) are major contributors to air pollution due to their easy gas-like penetration into the human organism, causing adverse health effects. This study analyzes UFP emissions by buses of different technologies (from Euro II till Euro V EEV - Enhanced Environmentally-friendly Vehicle) at low-load regimes. Additionally, the emission-reduction potential of retrofitting with a diesel particle filter (DPF) is demonstrated. A comparison of the measured, engine-out, particle number concentrations (PNC) for buses of different technological generations shows that no substantial reduction of engine-out emissions at low-load operating modes is observed for newer bus generations. Retrofitting the in-use urban and interurban buses of Euro II till Euro IV technologies by the VERT-certified DPF confirmed its high efficiency in reduction of UFP emissions. Particle-count filtration efficiency values of the retrofit DPF were found to be extremely high - greater than 99.8%, similar to that of the OEM filter in the Euro V bus.

  7. A PEMS study of the emissions of gaseous pollutants and ultrafine particles from gasoline- and diesel-fueled vehicles

    Science.gov (United States)

    Huang, Cheng; Lou, Diming; Hu, Zhiyuan; Feng, Qian; Chen, Yiran; Chen, Changhong; Tan, Piqiang; Yao, Di

    2013-10-01

    On-road emission measurements of gasoline- and diesel-fueled vehicles were conducted by a portable emission measurement system (PEMS) in Shanghai, China. Horiba OBS 2200 and TSI EEPS 3090 were employed to detect gaseous and ultrafine particle emissions during the tests. The driving-based emission factors of gaseous pollutants and particle mass and number were obtained on various road types. The average NOx emission factors of the diesel bus, diesel car, and gasoline car were 8.86, 0.68, and 0.17 g km-1, all of which were in excess of their emission limits. The particle number emission factors were 7.06 × 1014, 6.08 × 1014, and 1.57 × 1014 km-1, generally higher than the results for similar vehicle types reported in the previous studies. The size distributions of the particles emitted from the diesel vehicles were mainly concentrated in the accumulation mode, while those emitted from the gasoline car were mainly distributed in the nucleation mode. Both gaseous and particle emission rates exhibit significant correlations with the change in vehicle speed and power demand. The lowest emission rates for each vehicle type were produced during idling. The highest emission rates for each vehicle type were generally found in high-VSP bins. The particle number emission rates of the gasoline car show the strongest growth trend with increasing VSP and speed. The particle number emission for the gasoline car increased by 3 orders of magnitude from idling to the highest VSP and driving speed conditions. High engine power caused by aggressive driving or heavy loads is the main contributor to high emissions for these vehicles in real-world situations.

  8. Occupational exposures and chronic kidney disease: Possible associations with endotoxin and ultrafine particles.

    Science.gov (United States)

    Sponholtz, Todd R; Sandler, Dale P; Parks, Christine G; Applebaum, Katie M

    2016-01-01

    Chronic kidney disease (CKD) carries a high public health burden yet there is limited research on occupational factors, which are examined in this retrospective case-control study. Newly diagnosed cases of CKD (n = 547) and controls (n = 508) from North Carolina provided detailed work histories in telephone interviews. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). There was heterogeneity in the association of CKD and agricultural work, with crop production associated with increased risk and work with livestock associated with decreased risk. Work with cutting/cooling/lubricating oils was associated with a reduced risk. CKD risk was increased for working in dusty conditions. CKD risk was reduced in subjects with occupational exposures previously reported to involve endotoxin exposure. Further, exposure to dusty conditions was consistently associated with increased risk of glomerulonephritis across industry, suggesting that research on CKD and ultrafine particulates is needed. © 2015 Wiley Periodicals, Inc.

  9. Formation of bands of ultrafine beryllium particles during rapid solidification of Al-Be alloys: Modeling and direct observations

    International Nuclear Information System (INIS)

    Elmer, J.W.; Tanner, L.E.; Smith, P.M.; Wall, M.A.; Aziz, M.J.

    1994-01-01

    Rapid solidification of dilute hyper-eutectic and monotectic alloys sometimes produces a dispersion of ultrafine randomly-oriented particles that lie in arrays parallel to the advancing solidification front. The authors characterize this effect in Al-Be where Be-rich particles with diameters on the order of 10 nm form in arrays spaced approximately 25 nm apart, and they present a model of macroscopically steady state but microscopically oscillatory motion of the solidification front to explain this unusual microstructure. The proposed mechanism involves; (i) the build-up of rejected solute in a diffusional boundary layer which slows down the growing crystal matrix, (2) the boundary layer composition entering a metastable liquid miscibility gap, (3) homogeneous nucleation of solute rich liquid droplets in the boundary layer, and crystallization of these droplets, and (4) growth of the matrix past the droplets and its reformation into a planar interface. The size of the Be-rich particles is limited by the beryllium supersaturation in the diffusional boundary layer. A numerical model was developed to investigate this solidification mechanism, and the results of the model are in good agreement with experimental observations of rapidly solidified Al-5 at.% Be

  10. Comparison between particulate matter and ultrafine particle emission by electronic and normal cigarettes in real-life conditions.

    Science.gov (United States)

    Ruprecht, Ario Alberto; De Marco, Cinzia; Pozzi, Paolo; Munarini, Elena; Mazza, Roberto; Angellotti, Giorgia; Turla, Francesca; Boffi, Roberto

    2014-01-01

    Electronic cigarettes may be safer than conventional cigarettes as they generate less indoor pollution in terms of particulate matter (PM); however, recent findings in experimental conditions demonstrated that secondhand exposure to PM may be expected from e-cigarette smoking. The aim of the present study was to investigate the emission of PM generated by e-cigarettes and normal cigarettes under real-life conditions. Real-time measurement and comparison of PM and ultrafine particles (UFP) generated by electronic cigarettes with and without nicotine and by normal cigarettes in a 50 m3 office of an Italian comprehensive cancer center was performed. PM mass as PM1, PM2.5, PM7, PM10, total suspended particles (TSP) in μg/m³ and UFP in number of particles per cubic centimeter from 10 to 1,000 nanometers were measured. Outdoor concentrations were measured contemporaneously to compensate for urban background changes. Regardless of their nicotine content, e-cigarettes generated lower PM levels than conventional cigarettes. Notably, nicotine-enriched e-cigarettes produced lower PM levels than their nicotine-free counterparts. E-cigarettes appear to generate less indoor pollution than normal cigarettes and may therefore be safer. Further studies are required to investigate the long-term health-related effects of secondhand e-cigarette exposure.

  11. Contribution of various microenvironments to the daily personal exposure to ultrafine particles: Personal monitoring coupled with GPS tracking

    Science.gov (United States)

    Bekö, Gabriel; Kjeldsen, Birthe Uldahl; Olsen, Yulia; Schipperijn, Jasper; Wierzbicka, Aneta; Karottki, Dorina Gabriela; Toftum, Jørn; Loft, Steffen; Clausen, Geo

    2015-06-01

    Exposure to ultrafine particles (UFP) may have adverse health effects. Central monitoring stations do not represent the personal exposure to UFP accurately. Few studies have previously focused on personal exposure to UFP. Sixty non-smoking residents living in Copenhagen, Denmark were asked to carry a backpack equipped with a portable monitor, continuously recording particle number concentrations (PN), in order to measure the real-time individual exposure over a period of ˜48 h. A GPS logger was carried along with the particle monitor and allowed us to estimate the contribution of UFP exposure occurring in various microenvironments (residence, during active and passive transport, other indoor and outdoor environments) to the total daily exposure. On average, the fractional contribution of each microenvironment to the daily integrated personal exposure roughly corresponded to the fractions of the day the subjects spent in each microenvironment. The home environment accounted for 50% of the daily personal exposure. Indoor environments other than home or vehicles contributed with ˜40%. The highest median UFP concentration was obtained during passive transport (vehicles). However, being in transit or outdoors contributed 5% or less to the daily exposure. Additionally, the subjects recorded in a diary the periods when they were at home. With this approach, 66% of the total daily exposure was attributable to the home environment. The subjects spent 28% more time at home according to the diary, compared to the GPS. These results may indicate limitations of using diaries, but also possible inaccuracy and miss-classification in the GPS data.

  12. Magnetic Hysteresis in Nanocomposite Films Consisting of a Ferromagnetic AuCo Alloy and Ultrafine Co Particles

    Directory of Open Access Journals (Sweden)

    Federico Chinni

    2017-06-01

    Full Text Available One fundamental requirement in the search for novel magnetic materials is the possibility of predicting and controlling their magnetic anisotropy and hence the overall hysteretic behavior. We have studied the magnetism of Au:Co films (~30 nm thick with concentration ratios of 2:1, 1:1, and 1:2, grown by magnetron sputtering co-deposition on natively oxidized Si substrates. They consist of a AuCo ferromagnetic alloy in which segregated ultrafine Co particles are dispersed (the fractions of Co in the AuCo alloy and of segregated Co increase with decreasing the Au:Co ratio. We have observed an unexpected hysteretic behavior characterized by in-plane anisotropy and crossed branches in the loops measured along the hard magnetization direction. To elucidate this phenomenon, micromagnetic calculations have been performed for a simplified system composed of two exchange-coupled phases: a AuCo matrix surrounding a Co cluster, which represents an aggregate of particles. The hysteretic features are qualitatively well reproduced provided that the two phases have almost orthogonal anisotropy axes. This requirement can be plausibly fulfilled assuming a dominant magnetoelastic character of the anisotropy in both phases. The achieved conclusions expand the fundamental knowledge on nanocomposite magnetic materials, offering general guidelines for tuning the hysteretic properties of future engineered systems.

  13. Measured performance of filtration and ventilation systems for fine and ultrafine particles and ozone in an unoccupied modern California house

    Energy Technology Data Exchange (ETDEWEB)

    Singer, Brett C. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Delp, William W. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Black, Douglas R. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Walker, Iain S. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2016-12-01

    This study evaluated nine ventilation and filtration systems in an unoccupied 2006 house located 250m downwind of the I-80 freeway in Sacramento, California. Systems were evaluated for reducing indoor concentrations of outdoor particles in summer and fall/winter, ozone in summer, and particles from stir-fry cooking. Air exchange rate was measured continuously. Energy use was estimated for year-round operation in California. Exhaust ventilation without enhanced filtration produced indoor PM2.5 that was 70% lower than outdoors. Supply ventilation with MERV13 filtration provided slightly less protection whereas supply MERV16 filtration reduced PM2.55 by 97-98% relative to outdoors. Supply filtration systems used little energy but provided no benefits for indoor-generated particles. Systems with MERV13-16 filters in the recirculating heating and cooling unit (FAU) operating continuously or 20 min/h reduced PM2.5 by 93-98%. Across all systems, removal percentages were higher for ultrafine particles and lower for black carbon, relative to PM2.5. Indoor ozone was 3-4% of outdoors for all systems except an electronic air cleaner that produced ozone. Filtration via the FAU or portable filtration units lowered PM2.5 by 25-75% when operated over the hour following cooking. The energy for year-round operation of FAU filtration with an efficient blower motor was estimated at 600 kWh/year.

  14. Cloud condensation nuclei droplet growth kinetics of ultrafine particles during anthropogenic nucleation events

    Science.gov (United States)

    Shantz, N. C.; Pierce, J. R.; Chang, R. Y.-W.; Vlasenko, A.; Riipinen, I.; Sjostedt, S.; Slowik, J. G.; Wiebe, A.; Liggio, J.; Abbatt, J. P. D.; Leaitch, W. R.

    2012-02-01

    Evolution of the cloud condensation nucleus (CCN) activity of 36 ± 4 nm diameter anthropogenic aerosol particles at a water supersaturation of 1.0 ± 0.1% is examined for particle nucleation and growth. During the early stages of one event, relatively few of the anthropogenic particles at 36 nm were CCN active and their growth rates by water condensation were delayed relative to ammonium sulphate particles. As the event progressed, the particle size distribution evolved to larger sizes and the relative numbers of particles at 36 nm that were CCN active increased until all the 36 nm particles were activating at the end of the event. Based on the chemistry of larger particles and the results from an aerosol chemical microphysics box model, the increase in CCN activity of the particles was most likely the result of the condensation of sulphate in this case. Despite the increased CCN activity, a delay was observed in the initial growth of these particles into cloud droplets, which persisted even when the aerosol was most CCN active later in the afternoon. Simulations show that the delay in water uptake is explained by a reduction of the mass accommodation coefficient assuming that the composition of the 36 nm particles is the same as the measured composition of the 60-100 nm particles.

  15. Short-term effects of ultrafine particles on daily mortality by primary vehicle exhaust versus secondary origin in three Spanish cities.

    Science.gov (United States)

    Tobías, Aurelio; Rivas, Ioar; Reche, Cristina; Alastuey, Andrés; Rodríguez, Sergio; Fernández-Camacho, Rocío; Sánchez de la Campa, Ana M; de la Rosa, Jesús; Sunyer, Jordi; Querol, Xavier

    2018-02-01

    Evidence on the short-term effects of ultrafine particles (with diameterorigin of UFP determines their short-term effect on human health. BC is possibly the better parameter to evaluate the health effects of particulate vehicle exhaust emissions, although in areas influenced by domestic solid fuel combustion this should also be taken into account. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  16. Deposition velocities to Sorbus aria, Acer campestre, Populus deltoides x trichocarpa 'Beaupre', Pinus nigra and x Cupressocyparis leylandii for coarse, fine and ultra-fine particles in the urban environment

    International Nuclear Information System (INIS)

    Freer-Smith, P.H.; Beckett, K.P.; Taylor, Gail

    2005-01-01

    Trees are effective in the capture of particles from urban air to the extent that they can significantly improve urban air quality. As a result of their aerodynamic properties conifers, with their smaller leaves and more complex shoot structures, have been shown to capture larger amounts of particle matter than broadleaved trees. This study focuses on the effects of particle size on the deposition velocity of particles (Vg) to five urban tree species (coniferous and broadleaved) measured at two field sites, one urban and polluted and a second more rural. The larger uptake to conifers is confirmed, and for broadleaves and conifers Vg values are shown to be greater for ultra-fine particles (Dp<1.0 μm) than for fine and coarse particles. This is important since finer particles are more likely to be deposited deep in the alveoli of the human lung causing adverse health effects. The finer particle fraction is also shown to be transported further from the emission source; in this study a busy urban road. In further sets of data the aqueous soluble and insoluble fractions of the ultra-fines were separated, indicating that aqueous insoluble particles made up only a small proportion of the ultra-fines. Much of the ultra-fine fraction is present as aerosol. Chemical analysis of the aqueous soluble fractions of coarse, fine and ultra-fine particles showed the importance of nitrates, chloride and phosphates in all three size categories at the polluted and more rural location

  17. Op-amp based low noise amplifier for magnetic particle spectroscopy

    Directory of Open Access Journals (Sweden)

    Malhotra Ankit

    2017-09-01

    Full Text Available Magnetic particle spectrometry (MPS is a novel technique used to measure the magnetization response of superparamagnetic iron oxide nanoparticles (SPIONs. Therefore, it is one of the most important tools for the characterization of the SPIONs for imaging modalities such as magnetic particle imaging (MPI and Magnetic Resonance Imaging (MRI. In MPS, change in the particle magnetization induces a voltage in a dedicated receive coil. The amplitude of the signal can be very low (ranging from a few nV to 100 μV depending upon the concentration of the nanoparticles. Hence, the received signal needs to be amplified with a low noise amplifier (LNA. LNA’s paramount task is to amplify the received signal while keeping the noise induced by its own circuitry minimum. In the current research, we purpose modeling, design, and development of a prototyped LNA for MPS. The designed prototype LNA is based on the parallelization technique of Op-amps. The prototyped LNA consists of 16 Op-amps in parallel and is manufactured on a printed circuit board (PCB, with a size of 110.38 mm × 59.46 mm and 234 components. The input noise of the amplifier is approx. 546 pV/√Hz with a noise figure (NF of approx. 1.4 dB with a receive coil termination. Furthermore, a comparison between the prototyped LNA and a commercially available amplifier is shown.

  18. Ultrafine portland cement performance

    Directory of Open Access Journals (Sweden)

    C. Argiz

    2018-04-01

    Full Text Available By mixing several binder materials and additions with different degrees of fineness, the packing density of the final product may be improved. In this work, ultrafine cement and silica fume mixes were studied to optimize the properties of cement-based materials. This research was performed in mortars made of two types of cement (ultrafine Portland cement and common Portland cement and two types of silica fume with different particle-size distributions. Two Portland cement replacement ratios of 4% and 10% of silica fume were selected and added by means of a mechanical blending method. The results revealed that the effect of the finer silica fume mixed with the coarse cement enhances the mechanical properties and pore structure refinement at a later age. This improvement is somewhat lower in the case of ultrafine cement with silica fume.

  19. Evaluation of Multi-Year Continuous Measurements of Ultrafine Particles at Two Near-Road Stations in Toronto, Canada

    Science.gov (United States)

    Su, Y.; Sofowote, U.; Debosz, J.; Munoz, T.; Whitelaw, C.

    2013-12-01

    Particles with an aerodynamic diameter less than 100 nanometre (nm) are referred to as ultrafine particles (UFPs). Relative to fine and course particles, UFPs have greater potential to be suspended in air for a longer time and absorb toxic chemicals due to their larger surface areas per unit mass. UFPs could penetrate deep into the respiratory or cardiovascular systems and pose adverse health effects. In urban environments, primary sources of UFPs are from road traffic emissions and account for most of the total particle numbers. Controls on UPFs rely on better understanding of their emission sources and environmental behaviour. Ontario Ministry of the Environment have monitored UFPs since 2010 at two near-road stations in Toronto by using TSI 3031 UFP monitors. The two monitoring stations are approximately 20-30 meters adjacent to major arterial roads with over 20,000 vehicles per day. UFPs concentrations were monitored using six size channels: 20-30nm, 30-50nm, 50-70nm, 70-100nm, 100-200nm, and 200-450nm. Data are collected at time intervals of 11 or 15 minutes and averaged hourly. Concurrent measurements include wind speeds, wind directions, and concentrations of other air pollutants such as nitrogen oxides and black carbon. Data influenced by road-side traffic emissions were filtered by wind direction within 45° of normal to the road and wind speed greater than 1 m/s. Number concentrations were found higher for particles with sizes of 20-30nm and 30-50nm than for other sizes of UFPs. The observed particle number distributions are generally consistent with the theoretical understanding of particle nuclei mode and accumulation mode. During the day, for UFPs with sizes of 20-30nm and 30-50nm, elevated number concentrations were observed in morning traffic hours and to a less extent in the late afternoon. The elevated UFPs number concentrations coincided with nitrogen oxides and black carbon. Moreover, higher number concentrations were found on weekdays than

  20. Dilution effects on ultrafine particle emissions from Euro 5 and Euro 6 diesel and gasoline vehicles

    Science.gov (United States)

    Louis, Cédric; Liu, Yao; Martinet, Simon; D'Anna, Barbara; Valiente, Alvaro Martinez; Boreave, Antoinette; R'Mili, Badr; Tassel, Patrick; Perret, Pascal; André, Michel

    2017-11-01

    Dilution and temperature used during sampling of vehicle exhaust can modify particle number concentration and size distribution. Two experiments were performed on a chassis dynamometer to assess exhaust dilution and temperature on particle number and particle size distribution for Euro 5 and Euro 6 vehicles. In the first experiment, the effects of dilution (ratio from 8 to 4 000) and temperature (ranging from 50 °C to 150 °C) on particle quantification were investigated directly from tailpipe for a diesel and a gasoline Euro 5 vehicles. In the second experiment, particle emissions from Euro 6 diesel and gasoline vehicles directly sampled from the tailpipe were compared to the constant volume sampling (CVS) measurements under similar sampling conditions. Low primary dilutions (3-5) induced an increase in particle number concentration by a factor of 2 compared to high primary dilutions (12-20). Low dilution temperatures (50 °C) induced 1.4-3 times higher particle number concentration than high dilution temperatures (150 °C). For the Euro 6 gasoline vehicle with direct injection, constant volume sampling (CVS) particle number concentrations were higher than after the tailpipe by a factor of 6, 80 and 22 for Artemis urban, road and motorway, respectively. For the same vehicle, particle size distribution measured after the tailpipe was centred on 10 nm, and particles were smaller than the ones measured after CVS that was centred between 50 nm and 70 nm. The high particle concentration (≈106 #/cm3) and the growth of diameter, measured in the CVS, highlighted aerosol transformations, such as nucleation, condensation and coagulation occurring in the sampling system and this might have biased the particle measurements.

  1. Emission, distribution and health effects of ultrafine particles by road traffic; Emissies, verspreiding en gezondheidseffecten van ultrafijnstof door wegverkeer

    Energy Technology Data Exchange (ETDEWEB)

    Keuken, M.; Wilmink, I.; Tromp, P.; De Kluizenaar, Y.

    2009-02-15

    Epidemiological studies show that living in the vicinity of busy traffic routes is detrimental to health. This study quantifies the issue of ultrafine particles (UFPs). The results can be used to support technological and mobility policies for reducing exposure to UFPs. The study was conducted in three work packages: (1) WP1: emissions, distribution and health effects of UFPs by road traffic and curbing options; (2) WP2: exposure and toxicology of UFPs near the source; (3) WP3: shaping, testing and dissemination of a thorough TNO vision on the UFP theme. [Dutch] Epidemiologisch onderzoek wijst uit dat wonen nabij drukke verkeerswegen schadelijk is voor de gezondheid. In deze studie wordt het probleem van ultrafijne (UF) deeltjes gekwantificeerd en op basis daarvan kan het technologie- en mobiliteitsbeleid voor vermindering van de blootstelling aan UF worden ondersteund. Het UF-onderzoek (UFO) is uitgevoerd in drie werkpakketten: (1) WP1: emissies, verspreiding en gezondheidseffecten van UF door het wegverkeer en de mogelijkheden die te beperken; (2) WP2: blootstelling en toxicologie van UF nabij de bron; (3) WP3: vormen, toetsen en uitdragen van een gedegen TNO visie op het thema UF.

  2. Characterization of SiC based composite materials by the infiltration of ultra-fine SiC particles

    International Nuclear Information System (INIS)

    Lee, J.K.; Lee, S.P.; Byun, J.H.

    2010-01-01

    The fabrication route of SiC materials by the complex compound of ultra-fine SiC particles and oxide additive materials has been investigated. Especially, the effect of additive composition ratio on the characterization of SiC materials has been examined. The characterization of C/SiC composites reinforced with plain woven carbon fabrics was also investigated. The fiber preform for C/SiC composites was prepared by the infiltration of complex mixture into the carbon fabric structure. SiC based composite materials were fabricated by a pressure assisted liquid phase sintering process. SiC materials possessed a good density higher than about 3.0 Mg/m 3 , accompanying the creation of secondary phase by the chemical reaction of additive materials. C/SiC composites also represented a dense morphology in the intra-fiber bundle region, even if this material had a sintered density lower than that of monolithic SiC materials. The flexural strength of SiC materials was greatly affected by the composition ratio of additive materials.

  3. Detecting charging state of ultra-fine particles: instrumental development and ambient measurements

    Directory of Open Access Journals (Sweden)

    L. Laakso

    2007-01-01

    Full Text Available The importance of ion-induced nucleation in the lower atmosphere has been discussed for a long time. In this article we describe a new instrumental setup – Ion-DMPS – which can be used to detect contribution of ion-induced nucleation on atmospheric new particle formation events. The device measures positively and negatively charged particles with and without a bipolar charger. The ratio between "charger off" to "charger on" describes the charging state of aerosol particle population with respect to equilibrium. Values above one represent more charges than in an equilibrium (overcharged state, and values below unity stand for undercharged situation, when there is less charges in the particles than in the equilibrium. We performed several laboratory experiments to test the operation of the instrument. After the laboratory tests, we used the device to observe particle size distributions during atmospheric new particle formation in a boreal forest. We found that some of the events were clearly dominated by neutral nucleation but in some cases also ion-induced nucleation contributed to the new particle formation. We also found that negative and positive ions (charged particles behaved in a different manner, days with negative overcharging were more frequent than days with positive overcharging.

  4. Reduction of exposure to ultrafine particles by kitchen exhaust hoods: the effects of exhaust flow rates, particle size, and burner position.

    Science.gov (United States)

    Rim, Donghyun; Wallace, Lance; Nabinger, Steven; Persily, Andrew

    2012-08-15

    Cooking stoves, both gas and electric, are one of the strongest and most common sources of ultrafine particles (UFP) in homes. UFP have been shown to be associated with adverse health effects such as DNA damage and respiratory and cardiovascular diseases. This study investigates the effectiveness of kitchen exhaust hoods in reducing indoor levels of UFP emitted from a gas stove and oven. Measurements in an unoccupied manufactured house monitored size-resolved UFP (2 nm to 100 nm) concentrations from the gas stove and oven while varying range hood flow rate and burner position. The air change rate in the building was measured continuously based on the decay of a tracer gas (sulfur hexafluoride, SF(6)). The results show that range hood flow rate and burner position (front vs. rear) can have strong effects on the reduction of indoor levels of UFP released from the stove and oven, subsequently reducing occupant exposure to UFP. Higher range hood flow rates are generally more effective for UFP reduction, though the reduction varies with particle diameter. The influence of the range hood exhaust is larger for the back burner than for the front burner. The number-weighted particle reductions for range hood flow rates varying between 100 m(3)/h and 680 m(3)/h range from 31% to 94% for the front burner, from 54% to 98% for the back burner, and from 39% to 96% for the oven. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Phenomenological theory of size effects in ultrafine ferroelectric particles (PbTiO3-type)

    International Nuclear Information System (INIS)

    Jiang, B.; Bursill, L.A.

    1998-01-01

    A new phenomenological model is proposed and discussed to study the size effects on phase transitions in PbTiO 3 -type ferroelectric particles. This model, by taking size effects on the phenomenological Landau-Ginzburg-Devonshire coefficients into consideration, can successfully explain the size effects on Curie temperature, c/a ratio, thermal and dielectric properties of lead-titanate-type ferroelectric particles. Theoretical and experimental results for PbTiO 3 fine particles are also compared and discussed. The relationship between the current model and the model of Zhong et al (Phys. Rev. B 50, 698 (1994)) is also presented. (authors)

  6. Spatial variations in ambient ultrafine particle concentrations and the risk of incident prostate cancer: A case-control study.

    Science.gov (United States)

    Weichenthal, Scott; Lavigne, Eric; Valois, Marie-France; Hatzopoulou, Marianne; Van Ryswyk, Keith; Shekarrizfard, Maryam; Villeneuve, Paul J; Goldberg, Mark S; Parent, Marie-Elise

    2017-07-01

    Diesel exhaust contains large numbers of ultrafine particles (UFPs, <0.1µm) and is a recognized human carcinogen. However, epidemiological studies have yet to evaluate the relationship between UFPs and cancer incidence. We conducted a case-control study of UFPs and incident prostate cancer in Montreal, Canada. Cases were identified from all main Francophone hospitals in the Montreal area between 2005 and 2009. Population controls were identified from provincial electoral lists of French Montreal residents and frequency-matched to cases using 5-year age groups. UFP exposures were estimated using a land use regression model. Exposures were assigned to residential locations at the time of diagnosis/recruitment as well as approximately 10-years earlier to consider potential latency between exposure and disease onset. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated per interquartile range (IQR) increase in UFPs (approximately 4000 particles/cm 3 ) using logistic regression models adjusting for individual-level and ecological covariates. Ambient UFP concentrations were associated with an increased risk of prostate cancer (OR=1.10, 95% CI: 1.01, 1.19) in fully adjusted models when exposures were assigned to residences 10-years prior to diagnosis. This risk estimate increased slightly (OR=1.17, 95% CI; 1.01, 1.35) when modeled as a non-linear natural spline function. A smaller increased risk (OR=1.04, 95% CI: 0.97, 1.11) was observed when exposures were assigned to residences at the time of diagnosis. Exposure to ambient UFPs may increase the risk of prostate cancer. Future studies are needed to replicate this finding as this is the first study to evaluate this relationship. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

  7. Comparisons of Traffic-Related Ultrafine Particle Number Concentrations Measured in Two Urban Areas by Central, Residential, and Mobile Monitoring.

    Science.gov (United States)

    Simon, Matthew C; Hudda, Neelakshi; Naumova, Elena N; Levy, Jonathan I; Brugge, Doug; Durant, John L

    2017-11-01

    Traffic-related ultrafine particles (UFP; 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). Our objectives were to quantify ambient PNC differences between the three monitoring platforms, compare the temporal patterns and the spatial heterogeneity of PNC between the monitoring platforms, and identify factors that affect correlations across the platforms. We collected >12,000 hours of measurements at the central sites, 1,000 hours of measurements at each of 20 residential sites in the two study areas, and >120 hours of mobile measurements over the course of ~1 year in each study area. Our results show differences between the monitoring strategies: mean one-minute PNC on-roads were higher (64,000 and 32,000 particles/cm 3 in Boston and Chelsea, respectively) compared to central-site measurements (23,000 and 19,000 particles/cm 3 ) and both were higher than at residences (14,000 and 15,000 particles/cm 3 ). Temporal correlations and spatial heterogeneity also differed between the platforms. Temporal correlations were generally highest between central and residential sites, and lowest between central-site and on-road measurements. We observed the greatest spatial heterogeneity across monitoring platforms during the morning rush hours (06:00-09:00) and the lowest during the overnight hours (18:00-06:00). Longer averaging times (days and hours vs. minutes) increased temporal correlations (Pearson correlations were 0.69 and 0.60 vs. 0.39 in Boston; 0.71 and 0.61 vs. 0.45 in Chelsea) and reduced spatial heterogeneity (coefficients of divergence were 0.24 and 0.29 vs. 0.33 in Boston; 0.20 and 0.27 vs. 0.31 in Chelsea). Our results suggest that combining stationary and mobile monitoring may lead

  8. Comparisons of traffic-related ultrafine particle number concentrations measured in two urban areas by central, residential, and mobile monitoring

    Science.gov (United States)

    Simon, Matthew C.; Hudda, Neelakshi; Naumova, Elena N.; Levy, Jonathan I.; Brugge, Doug; Durant, John L.

    2017-11-01

    Traffic-related ultrafine particles (UFP; 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). Our objectives were to quantify ambient PNC differences between the three monitoring platforms, compare the temporal patterns and the spatial heterogeneity of PNC between the monitoring platforms, and identify factors that affect correlations across the platforms. We collected >12,000 h of measurements at the central sites, 1000 h of measurements at each of 20 residential sites in the two study areas, and >120 h of mobile measurements over the course of ∼1 year in each study area. Our results show differences between the monitoring strategies: mean 1 min PNC on-roads were higher (64,000 and 32,000 particles/cm3 in Boston and Chelsea, respectively) compared to central-site measurements (23,000 and 19,000 particles/cm3) and both were higher than at residences (14,000 and 15,000 particles/cm3). Temporal correlations and spatial heterogeneity also differed between the platforms. Temporal correlations were generally highest between central and residential sites, and lowest between central-site and on-road measurements. We observed the greatest spatial heterogeneity across monitoring platforms during the morning rush hours (06:00-09:00) and the lowest during the overnight hours (18:00-06:00). Longer averaging times (days and hours vs. minutes) increased temporal correlations (Pearson correlations were 0.69 and 0.60 vs. 0.39 in Boston; 0.71 and 0.61 vs. 0.45 in Chelsea) and reduced spatial heterogeneity (coefficients of divergence were 0.24 and 0.29 vs. 0.33 in Boston; 0.20 and 0.27 vs. 0.31 in Chelsea). Our results suggest that combining stationary and mobile monitoring may lead to improved characterization of

  9. Capture Efficiency of Cooking-Related Fine and Ultrafine Particles by Residential Exhaust Hoods

    Energy Technology Data Exchange (ETDEWEB)

    Lunden, Melissa M.; Delp, William W.

    2014-06-05

    Effective exhaust hoods can mitigate the indoor air quality impacts of pollutant emissions from residential cooking. This study reports capture efficiencies (CE) measured for cooking generated particles for scripted cooking procedures in a 121-m3 chamber with kitchenette. CEs also were measured for burner produced CO2 during cooking and separately for pots and pans containing water. The study used four exhaust hoods previously tested by Delp and Singer (Environ. Sci. Technol., 2012, 46, 6167-6173). For pan-frying a hamburger over medium heat on the back burner, CEs for particles were similar to those for burner produced CO2 and mostly above 80percent. For stir-frying green beans in a wok (high heat, front burner), CEs for burner CO2 during cooking varied by hood and airflow: CEs were 34-38percent for low (51?68 L s-1) and 54?72percent for high (109?138 L s-1) settings. CEs for 0.3?2.0 ?m particles during front burner stir-frying were 3?11percent on low and 16?70percent on high settings. Results indicate that CEs measured for burner CO2 are not predictive of CEs of cooking-generated particles under all conditions, but they may be suitable to identify devices with CEs above 80percent both for burner combustion products and for cooking-related particles.

  10. Capture efficiency of cooking-related fine and ultrafine particles by residential exhaust hoods.

    Science.gov (United States)

    Lunden, M M; Delp, W W; Singer, B C

    2015-02-01

    Effective exhaust hoods can mitigate the indoor air quality impacts of pollutant emissions from residential cooking. This study reports capture efficiencies (CE) measured for cooking-generated particles for scripted cooking procedures in a 121-m3 chamber with kitchenette. CEs also were measured for burner produced CO2 during cooking and separately for pots and pans containing water. The study used four exhaust hoods previously tested by Delp and Singer (Environ. Sci. Technol., 2012, 46, 6167-6173). For pan-frying a hamburger over medium heat on the back burner, CEs for particles were similar to those for burner produced CO2 and mostly above 80%. For stir-frying green beans in a wok (high heat, front burner), CEs for burner CO2 during cooking varied by hood and airflow: CEs were 34-38% for low (51-68 l/s) and 54-72% for high (109-138 l/s) settings. CEs for 0.3-2.0 μm particles during front burner stir-frying were 3-11% on low and 16-70% on high settings. Results indicate that CEs measured for burner CO2 are not predictive of CEs of cooking-generated particles under all conditions, but they may be suitable to identify devices with CEs above 80% both for burner combustion products and for cooking-related particles. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

  11. An electrical sensor for long-term monitoring of ultrafine particles in workplaces

    International Nuclear Information System (INIS)

    Lanki, Timo; Taimisto, Pekka; Tikkanen, Juha; Janka, Kauko; Lehtimaeki, Matti

    2011-01-01

    Pegasor Oy Ltd. (Finland) has developed a diffusion charging measurement device that enables continuous monitoring of fine particle concentration at a low initial and lifecycle cost. The innovation, for which an international process and apparatus patent has been applied for, opens doors for monitoring nanoparticle concentrations in workplaces. The Pegasor Particle Sensor (PPS) operates by electrostatically charging particles passing through the sensor and then measuring the current caused by the charged particles as they leave the sensor. The particles never touch the sensor and so never accumulate on its surfaces or need to be cleaned off. The sensor uses an ejector pump to draw a constant sample flow into the sensing area where it is mixed with the clean, charged pump flow air (provided by an external source). The sample flow containing charged particles passes through the sensor. The current generated by the charge leaving the detection volume is measured and related to the particle surface area. This system is extremely simple and reliable - no contact, no moving parts, and all critical parts of the sensor are constantly cleaned by a stream of fresh, filtered air. Due to the ejector pump, the sample flow, and respectively the sensor response is independent of the flow and pressure conditions around the sampling inlet. Tests with the Pegasor Particle Sensor have been conducted in a laboratory, and at a workplace producing nanoparticles for glass coatings. A new measurement protocol has been designed to ensure that process workers are not exposed to unusually high nanoparticle concentrations at any time during their working day. One sensor is placed inside the process line, and a light alarm system indicates the worker not to open any protective shielding or ventilation systems before concentration inside has reached background levels. The benefits of PPS in industrial hygiene are that the same monitoring technology can be used at the source as well as at the

  12. Ultrafine particles and nitrogen oxides generated by gas and electric cooking

    OpenAIRE

    Dennekamp, M; Howarth, S; Dick, C; Cherrie, J; Donaldson, K; Seaton, A

    2001-01-01

    OBJECTIVES—To measure the concentrations of particles less than 100 nm diameter and of oxides of nitrogen generated by cooking with gas and electricity, to comment on possible hazards to health in poorly ventilated kitchens.
METHODS—Experiments with gas and electric rings, grills, and ovens were used to compare different cooking procedures. Nitrogen oxides (NOx) were measured by a chemiluminescent ML9841A NOx analyser. A TSI 3934 scanning mobility particle sizer was used to measure average nu...

  13. Exposure to Ultrafine Particles from Ambient Air and Oxidative Stress-Induced DNA Damage

    DEFF Research Database (Denmark)

    Bräuner, Elvira Vaclavik; Forchhammer, Lykke; Møller, Peter

    2007-01-01

    mononuclear cells (PBMCs) during controlled exposure to urban air particles with assignment of number concentration (NC) to four size modes with average diameters of 12, 23, 57, and 212 nm. DESIGN. Twenty-nine healthy adults participated in a randomized, two-factor cross-over study with or without biking...... exercise for 180 min and with exposure to particles (NC 6169-15362/cm3) or filtered air (NC 91-542/cm3) for 24 hr. METHODS: The levels of DNA strand breaks (SBs), oxidized purines as formamidopyrimidine DNA glycolase (FPG) sites, and activity of 7,8-dihydro-8-oxoguanine-DNA glycosylase (OGG1) in PBMCs were...

  14. Charge-sensitive poly-silicon TFT amplifiers for a-Si:H pixel particle detectors

    International Nuclear Information System (INIS)

    Cho, G.; Perez-Mendez, V.; Hack, M.; Lewis, A.

    1992-04-01

    Prototype charge-sensitive poly-Si TFT amplifiers have been made for the amplification of signals (from an a-Si:H pixel diode used as an ionizing particle detector). They consist of a charge-sensitive gain stage, a voltage gain stage and a source follower output stage. The gain-bandwidth product of the amplifier is ∼ 300 MHz. When the amplifier is connected to a pixel detector of 0.2 pF, it gives a charge-to-voltage gain of ∼ 0.02 mV/electrons with a pulse rise time less than 100 nsec. An equivalent noise charge of the front-end TFT is ∼ 1000 electrons for a shaping time of 1 μsec

  15. Air quality in the German-Czech border region: A focus on harmful fractions of PM and ultrafine particles

    Science.gov (United States)

    Schladitz, Alexander; Leníček, Jan; Beneš, Ivan; Kováč, Martin; Skorkovský, Jiří; Soukup, Aleš; Jandlová, Jana; Poulain, Laurent; Plachá, Helena; Löschau, Gunter; Wiedensohler, Alfred

    2015-12-01

    A comprehensive air quality study has been carried out at two urban background sites in Annaberg-Buchholz (Germany) and Ústí nad Labem (Czech Republic) in the German-Czech border region between January 2012 and June 2014. Special attention was paid to quantify harmful fractions of particulate matter (PM) and ultrafine particle number concentration (UFP) from solid fuel combustion and vehicular traffic. Source type contributions of UFP were quantified by using the daily concentration courses of UFP and nitrogen oxide. Two different source apportionment techniques were used to quantify relative and absolute mass contributions: positive matrix factorization for total PM2.5 and elemental carbon in PM2.5 and chemical mass balance for total PM1 and organic carbon in PM1. Contributions from solid fuel combustion strongly differed between the non-heating period (April-September) and the heating period (October-March). Major sources of solid fuel combustion in this study were wood and domestic coal combustion, while the proportion of industrial coal combustion was low (source of organic carbon ranging from 34% to 43%. Wood combustion was an important source of organic carbon in Annaberg-Buchholz throughout the year. Heavy metals and less volatile polycyclic aromatic hydrocarbons (PAH) in the accumulation mode were related to solid fuel combustion with enhanced concentrations during the heating period. In contrast, vehicular PAH emissions were allocated to the Aitken mode. Only in Ústí nad Labem a significant contribution of photochemical new particle formation (e.g. from sulfur dioxide) to UFP of almost 50% was observed during noontime. UFPs from traffic emissions (nucleation particles) and primary emitted soot particles dominated at both sites during the rest of the day. The methodology of a combined source apportionment of UFP and PM can be adapted to other regions of the world with similar problems of atmospheric pollution to calculate the relative risk in

  16. Ultrafine Particle Metrics and Research Considerations: Review of the 2015 UFP Workshop

    Directory of Open Access Journals (Sweden)

    Richard W. Baldauf

    2016-10-01

    Full Text Available In February 2015, the United States Environmental Protection Agency (EPA sponsored a workshop in Research Triangle Park, NC, USA to review the current state of the science one missions, air quality impacts, and health effects associated with exposures to ultrafine particles[1].[...

  17. Desorption of SVOCs from Heated Surfaces in the Form of Ultrafine Particles

    DEFF Research Database (Denmark)

    Wallace, Lance A.; Ott, Wayne R.; Weschler, Charles J.

    2017-01-01

    of the accumulation rate of SVOCs on surfaces were similar to those in studies of organic film buildup on indoor windows. Transfer of skin oils by touching the glass or foil surfaces, or after washing the glass surface with detergent and bare hands, was also observed, with measured particle production comparable...

  18. Lung cancer risk in relation to traffic-related nano/ultrafine particle-bound PAHs exposure: a preliminary probabilistic assessment.

    Science.gov (United States)

    Liao, Chung-Min; Chio, Chia-Pin; Chen, Wei-Yu; Ju, Yun-Ru; Li, Wen-Hsuan; Cheng, Yi-Hsien; Liao, Vivian Hsiu-Chuan; Chen, Szu-Chieh; Ling, Min-Pei

    2011-06-15

    Exposures to carcinogenic polycyclic aromatic hydrocarbons (PAHs) have been linked to human lung cancer. The purpose of this study was to assess lung cancer risk caused by inhalation exposure to nano/ultrafine particle-bound PAHs at the population level in Taiwan appraised with recent published data. A human respiratory tract model was linked with a physiologically based pharmacokinetic model to estimate deposition fraction and internal organic-specific PAHs doses. A probabilistic risk assessment framework was developed to estimate potential lung cancer risk. We reanalyzed particle size distribution, total-PAHs, particle-bound benzo(a)pyrene (B[a]P) and PM concentrations. A dose-response profile describing the relationships between external B[a]P concentration and lung cancer risk response was constructed based on population attributable fraction (PAF). We found that 90% probability lung cancer risks ranged from 10(-5) to 10(-4) for traffic-related nano and ultrafine particle-bound PAHs, indicating a potential lung cancer risk. The particle size-specific PAF-based excess annual lung cancer incidence rate due to PAHs exposure was estimated to be less than 1 per 100,000 population, indicating a mild risk factor for lung cancer. We concluded that probabilistic risk assessment linked PAF for limiting cumulative PAHs emissions to reduce lung cancer risk plays a prominent role in future government risk assessment program. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. Redox Dynamics of Mixed Metal (Mn, Cr, and Fe) Ultrafine Particles

    Energy Technology Data Exchange (ETDEWEB)

    Nico, Peter S.; Kumfer, Benjamin M.; Kennedy, Ian M.; Anastasio, Cort

    2008-08-01

    The impact of particle composition on metal oxidation state, and on changes in oxidation state with simulated atmospheric aging, are investigated experimentally in flame-generated nanoparticles containing Mn, Cr, and Fe. The results demonstrate that the initial fraction of Cr(VI) within the particles decreases with increasing total metal concentration in the flame. In contrast, the initial Mn oxidation state was only partly controlled by metal loading, suggesting the importance of other factors. Two reaction pathways, one reductive and one oxidative, were found to be operating simultaneously during simulated atmospheric aging. The oxidative pathway depended upon the presence of simulated sunlight and O{sub 3}, whereas the reductive pathway occurred in the presence of simulated sunlight alone. The reductive pathway appears to be rapid but transient, allowing the oxidative pathway to dominate with longer aging times, i.e. greater than {approx}8 hours. The presence of Mn within the particles enhanced the importance of the oxidative pathway, leading to more net Cr oxidation during aging implying that Mn can mediate oxidation by removal of electrons from other particulate metals.

  20. Long-term exposure to ambient ultrafine particles and respiratory disease incidence in in Toronto, Canada: a cohort study.

    Science.gov (United States)

    Weichenthal, Scott; Bai, Li; Hatzopoulou, Marianne; Van Ryswyk, Keith; Kwong, Jeffrey C; Jerrett, Michael; van Donkelaar, Aaron; Martin, Randall V; Burnett, Richard T; Lu, Hong; Chen, Hong

    2017-06-19

    Little is known about the long-term health effects of ambient ultrafine particles (respiratory disease incidence. In this study, we examined the relationship between long-term exposure to ambient UFPs and the incidence of lung cancer, adult-onset asthma, and chronic obstructive pulmonary disease (COPD). Our study cohort included approximately 1.1 million adults who resided in Toronto, Canada and who were followed for disease incidence between 1996 and 2012. UFP exposures were assigned to residential locations using a land use regression model. Random-effect Cox proportional hazard models were used to estimate hazard ratios (HRs) describing the association between ambient UFPs and respiratory disease incidence adjusting for ambient fine particulate air pollution (PM 2.5 ), NO 2 , and other individual/neighbourhood-level covariates. In total, 74,543 incident cases of COPD, 87,141 cases of asthma, and 12,908 cases of lung cancer were observed during follow-up period. In single pollutant models, each interquartile increase in ambient UFPs was associated with incident COPD (HR = 1.06, 95% CI: 1.05, 1.09) but not asthma (HR = 1.00, 95% CI: 1.00, 1.01) or lung cancer (HR = 1.00, 95% CI: 0.97, 1.03). Additional adjustment for NO 2 attenuated the association between UFPs and COPD and the HR was no longer elevated (HR = 1.01, 95% CI: 0.98, 1.03). PM 2.5 and NO 2 were each associated with increased incidence of all three outcomes but risk estimates for lung cancer were sensitive to indirect adjustment for smoking and body mass index. In general, we did not observe clear evidence of positive associations between long-term exposure to ambient UFPs and respiratory disease incidence independent of other air pollutants. Further replication is required as few studies have evaluated these relationships.

  1. Where to locate transit stops: Cross-intersection profiles of ultrafine particles and implications for pedestrian exposure.

    Science.gov (United States)

    Choi, Wonsik; Ranasinghe, Dilhara; DeShazo, J R; Kim, Jae-Jin; Paulson, Suzanne E

    2018-02-01

    Epidemiological studies have shown that exposure to traffic-related pollutants increases incidence of adverse health outcomes. Transit users in cities across the globe commonly spend 15-45 min or more waiting at transit stops each day, often at locations with high levels of pollution from traffic. Here, we investigate the characteristics of concentration profiles of ultrafine particles (UFP) with 5 m spatial resolution across intersections, to determine the best place to site transit stops to minimize exposures. Cross-intersection UFP profiles were derived from 1744 profiles covering 90 m before and after each intersection center with a mobile monitoring platform. Measurements were made at 10 signalized intersections located at six urban sites, each with a distinct built environment, during both mornings and afternoons. Measurements were made within 1.5 m of the sidewalk and approximately at breathing height (1.5 m above ground level) to approximate sidewalk exposures. UFP profiles were strongly influenced by high emissions from vehicle stops and accelerations, and peaked within 30 m of intersection centers; from there concentrations decreased sharply with distance. Peak concentrations averaged about 90% higher than the minima along the block. They were accompanied by more frequent and larger transient concentration spikes, increasing the chance of people near the intersection being exposed to both short-term extremely high concentration spikes and higher average concentrations. The decays are somewhat larger before the intersection than after the intersection, however as siting transit stops after intersections is preferred for smooth traffic flow, we focus on after the intersection. Simple time-duration exposure calculations combined with breathing rates suggest moving a bus stop from 20 to 40-50 m after the intersection can reduce transit-users' exposure levels to total UFP substantially, in proportion to the reciprocal of the magnitude of elevation at

  2. Air pollution upregulates endothelial cell procoagulant activity via ultrafine particle-induced oxidant signaling and tissue factor expression.

    Science.gov (United States)

    Snow, S J; Cheng, W; Wolberg, A S; Carraway, M S

    2014-07-01

    Air pollution exposure is associated with cardiovascular events triggered by clot formation. Endothelial activation and initiation of coagulation are pathophysiological mechanisms that could link inhaled air pollutants to vascular events. Here we investigated the underlying mechanisms of increased endothelial cell procoagulant activity following exposure to soluble components of ultrafine particles (soluble UF). Human coronary artery endothelial cells (HCAEC) were exposed to soluble UF and assessed for their ability to trigger procoagulant activity in platelet-free plasma. Exposed HCAEC triggered earlier thrombin generation and faster fibrin clot formation, which was abolished by an anti-tissue factor (TF) antibody, indicating TF-dependent effects. Soluble UF exposure increased TF mRNA expression without compensatory increases in key anticoagulant proteins. To identify early events that regulate TF expression, we measured endothelial H2O2 production following soluble UF exposure and identified the enzymatic source. Soluble UF exposure increased endothelial H2O2 production, and antioxidants attenuated UF-induced upregulation of TF, linking the procoagulant responses to reactive oxygen species (ROS) formation. Chemical inhibitors and RNA silencing showed that NOX-4, an important endothelial source of H2O2, was involved in UF-induced upregulation of TF mRNA. These data indicate that soluble UF exposure induces endothelial cell procoagulant activity, which involves de novo TF synthesis, ROS production, and the NOX-4 enzyme. These findings provide mechanistic insight into the adverse cardiovascular effects associated with air pollution exposure. Published by Oxford University Press on behalf of Toxicological Sciences 2014. This work is written by (a) US Government employee(s) and is in the public domain in the US.

  3. Longitudinal associations of long-term exposure to ultrafine particles with blood pressure and systemic inflammation in Puerto Rican adults.

    Science.gov (United States)

    Corlin, Laura; Woodin, Mark; Hart, Jaime E; Simon, Matthew C; Gute, David M; Stowell, Joanna; Tucker, Katherine L; Durant, John L; Brugge, Doug

    2018-04-05

    Few longitudinal studies have examined the association between ultrafine particulate matter (UFP, particles blood pressure and high sensitivity C-reactive protein (hsCRP, a biomarker of systemic inflammation). Residential annual average UFP exposure (measured as particle number concentration, PNC) was assigned using a model accounting for spatial and temporal trends. We also adjusted PNC values for participants' inhalation rate to obtain the particle inhalation rate (PIR) as a secondary exposure measure. Multilevel linear models with a random intercept for each participant were used to examine the association of UFP with blood pressure and hsCRP. Overall, in adjusted models, an inter-quartile range increase in PNC was associated with increased hsCRP (β = 6.8; 95% CI = - 0.3, 14.0%) but not with increased systolic blood pressure (β = 0.96; 95% CI = - 0.33, 2.25 mmHg), pulse pressure (β = 0.70; 95% CI = - 0.27, 1.67 mmHg), or diastolic blood pressure (β = 0.55; 95% CI = - 0.20, 1.30 mmHg). There were generally stronger positive associations among women and never smokers. Among men, there were inverse associations of PNC with systolic blood pressure and pulse pressure. In contrast to the primary findings, an inter-quartile range increase in the PIR was positively associated with systolic blood pressure (β = 1.03; 95% CI = 0.00, 2.06 mmHg) and diastolic blood pressure (β = 1.01; 95% CI = 0.36, 1.66 mmHg), but not with pulse pressure or hsCRP. We observed that exposure to PNC was associated with increases in measures of CVD risk markers, especially among certain sub-populations. The exploratory PIR exposure metric should be further developed.

  4. Production of ultrafine particles of high-temperature tetragonal WO3 by dc arc discharge in Ar-O2 gases

    International Nuclear Information System (INIS)

    Guo Yumei; Murata, Norihiko; Ono, Kazuya; Okazaki, Tsugio

    2005-01-01

    Ultrafine particles of WO 3 are successfully produced by dc arc discharge in Ar-O 2 gases. Particle sizes are distributed from 10 nm to 1 μm depending on production conditions: gas pressure, collection position and discharge current. Observations of the cooled particles by electron microscopy indicate that the WO 3 particles are tetragonal, a phase that is usually only stable above 725 deg. C. The octahedral crystals are bounded by eight {1 0 1} faces and occasionally truncated by {1 0 0} and/or {0 0 1} faces. This method of producing WO 3 by dc arc discharge therefore affords a high-temperature phase that is preserved upon cooling to room temperature

  5. Inter-particle interactions and magnetocaloric effect in a sample of ultrafine Fe1-x Hgx particles in Hg

    DEFF Research Database (Denmark)

    Pedersen, Michael Stanley; Mørup, Steen; Linderoth, S.

    1997-01-01

    to a state in which the magnetic moments of the particles are ordered. The magnetic entropy change induced by application of a magnetic field was determined in the temperature range from 70 to 200 K. When the sample was magnetized in 1 T the magnetic entropy change was almost constant in the temperature...... range from 130 to 200 K. In an applied field of 0.1 T, the entropy change was lower, and decreased with increasing temperature in the same temperature range. A model which takes into account the magnetic interactions between the particles was found to give a better description of the magnetic entropy...

  6. PAH, BTEX, carbonyl compound, black-carbon, NO2 and ultrafine particle dynamometer bench emissions for Euro 4 and Euro 5 diesel and gasoline passenger cars

    Science.gov (United States)

    Louis, Cédric; Liu, Yao; Tassel, Patrick; Perret, Pascal; Chaumond, Agnès; André, Michel

    2016-09-01

    Although implementing Diesel particulate filters (DPF) and other novel aftertreatment technologies makes it possible to achieve significant reductions in particle mass emissions, it may induce the release of ultrafine particles and emissions of many other unregulated compounds. This paper focuses on (i) ultrafine particles, black carbon, BTEX, PAH, carbonyl compounds, and NO2 emissions from Euro 4 and Euro 5 Diesel and gasoline passenger cars, (ii) the influence of driving conditions (e.g., cold start, urban, rural and motorway conditions), and (iii) the impact of additive and catalysed DPF devices on vehicle emissions. Chassis dynamometer tests were conducted on four Euro 5 vehicles and two Euro 4 vehicles: gasoline vehicles with and without direct injection system and Diesel vehicles equipped with additive and catalysed particulate filters. The results showed that compared to hot-start cycles, cold-start urban cycles increased all pollutant emissions by a factor of two. The sole exception was NO2, which was reduced by a factor of 1.3-6. Particulate and black carbon emissions from the gasoline engines were significantly higher than those from the Diesel engines equipped with DPF. Moreover, the catalysed DPF emitted about 3-10 times more carbonyl compounds and particles than additive DPF, respectively, during urban driving cycles, while the additive DPF vehicles emitted 2 and 5 times more BTEX and carbonyl compounds during motorway driving cycles. Regarding particle number distribution, the motorway driving cycle induced the emission of particles smaller in diameter (mode at 15 nm) than the urban cold-start cycle (mode at 80-100 nm). The results showed a clear positive correlation between particle, black carbon, and BTEX emissions, and a negative correlation between particles and NO2.

  7. Signal recognition particle assembly in relation to the function of amplified nucleoli of Xenopus oocytes.

    Science.gov (United States)

    Sommerville, John; Brumwell, Craig L; Politz, Joan C Ritland; Pederson, Thoru

    2005-03-15

    The signal recognition particle (SRP) is a ribonucleoprotein machine that controls the translation and intracellular sorting of membrane and secreted proteins. The SRP contains a core RNA subunit with which six proteins are assembled. Recent work in both yeast and mammalian cells has identified the nucleolus as a possible initial site of SRP assembly. In the present study, SRP RNA and protein components were identified in the extrachromosomal, amplified nucleoli of Xenopus laevis oocytes. Fluorescent SRP RNA microinjected into the oocyte nucleus became specifically localized in the nucleoli, and endogenous SRP RNA was also detected in oocyte nucleoli by RNA in situ hybridization. An initial step in the assembly of SRP involves the binding of the SRP19 protein to SRP RNA. When green fluorescent protein (GFP)-tagged SRP19 protein was injected into the oocyte cytoplasm it was imported into the nucleus and became concentrated in the amplified nucleoli. After visiting the amplified nucleoli, GFP-tagged SRP19 protein was detected in the cytoplasm in a ribonucleoprotein complex, having a sedimentation coefficient characteristic of the SRP. These results suggest that the amplified nucleoli of Xenopus oocytes produce maternal stores not only of ribosomes, the classical product of nucleoli, but also of SRP, presumably as a global developmental strategy for stockpiling translational machinery for early embryogenesis.

  8. Robustness of intra urban land-use regression models for ultrafine particles and black carbon based on mobile monitoring.

    Science.gov (United States)

    Kerckhoffs, Jules; Hoek, Gerard; Vlaanderen, Jelle; van Nunen, Erik; Messier, Kyle; Brunekreef, Bert; Gulliver, John; Vermeulen, Roel

    2017-11-01

    Land-use regression (LUR) models for ultrafine particles (UFP) and Black Carbon (BC) in urban areas have been developed using short-term stationary monitoring or mobile platforms in order to capture the high variability of these pollutants. However, little is known about the comparability of predictions of mobile and short-term stationary models and especially the validity of these models for assessing residential exposures and the robustness of model predictions developed in different campaigns. We used an electric car to collect mobile measurements (n = 5236 unique road segments) and short-term stationary measurements (3 × 30min, n = 240) of UFP and BC in three Dutch cities (Amsterdam, Utrecht, Maastricht) in 2014-2015. Predictions of LUR models based on mobile measurements were compared to (i) measured concentrations at the short-term stationary sites, (ii) LUR model predictions based on short-term stationary measurements at 1500 random addresses in the three cities, (iii) externally obtained home outdoor measurements (3 × 24h samples; n = 42) and (iv) predictions of a LUR model developed based upon a 2013 mobile campaign in two cities (Amsterdam, Rotterdam). Despite the poor model R 2 of 15%, the ability of mobile UFP models to predict measurements with longer averaging time increased substantially from 36% for short-term stationary measurements to 57% for home outdoor measurements. In contrast, the mobile BC model only predicted 14% of the variation in the short-term stationary sites and also 14% of the home outdoor sites. Models based upon mobile and short-term stationary monitoring provided fairly high correlated predictions of UFP concentrations at 1500 randomly selected addresses in the three Dutch cities (R 2 = 0.64). We found higher UFP predictions (of about 30%) based on mobile models opposed to short-term model predictions and home outdoor measurements with no clear geospatial patterns. The mobile model for UFP was stable over different settings as

  9. Characterizing and predicting ultrafine particle counts in Canadian classrooms during the winter months: model development and evaluation.

    Science.gov (United States)

    Weichenthal, Scott; Dufresne, André; Infante-Rivard, Claire; Joseph, Lawrence

    2008-03-01

    School classrooms are potentially important micro-environments for childhood exposures owing to the large amount of time children spend in these locations. While a number of airborne contaminants may be present in schools, to date few studies have examined ultrafine particle (0.02-1 microm) (UFP) levels in classrooms. In this study, our objective was to characterize UFP counts (cm(-3)) in classrooms during the winter months and to develop a model to predict such exposures based on ambient weather conditions and outdoor UFPs, as well as classroom characteristics such as size, temperature, relative humidity, and carbon dioxide levels. In total, UFP count data were collected on 60 occasions in 37 occupied classrooms at one elementary school and one secondary school in Pembroke, Ontario. On average, outdoor UFP levels exceeded indoor measures by 8989 cm(-3) (95% confidence interval (CI): 6382, 11596), and classroom UFP counts were similar at both schools with a combined average of 5017 cm(-3) (95% CI: 4300, 5734). Of the variables examined only wind speed and outdoor UFPs were important determinants of classrooms UFP levels. Specifically, each 10 km/h increase in wind speed corresponded to an 1873 cm(-3) (95% CI: 825, 2920) decrease in classroom UFP counts, and each 10000 cm(-3) increase in outdoor UFPs corresponded to a 1550 cm(-3) (95% CI: 930, 2171) increase in classroom UFP levels. However, high correlations between these two predictors meant that the independent effects of wind speed and outdoor UFPs could not be separated in multivariable models, and only outdoor UFP counts were included in the final predictive model. To evaluate model performance, classroom UFP counts were collected for 8 days at two new schools and compared to predicted values based on outdoor UFP measures. A moderate correlation was observed between measured and predicted classroom UFP counts (r=0.63) for both schools combined, but this relationship was not valid on days in which a strong

  10. Characterizing and predicting ultrafine particle counts in Canadian classrooms during the winter months: Model development and evaluation

    International Nuclear Information System (INIS)

    Weichenthal, Scott; Dufresne, Andre; Infante-Rivard, Claire; Joseph, Lawrence

    2008-01-01

    School classrooms are potentially important micro-environments for childhood exposures owing to the large amount of time children spend in these locations. While a number of airborne contaminants may be present in schools, to date few studies have examined ultrafine particle (0.02-1 μm) (UFP) levels in classrooms. In this study, our objective was to characterize UFP counts (cm -3 ) in classrooms during the winter months and to develop a model to predict such exposures based on ambient weather conditions and outdoor UFPs, as well as classroom characteristics such as size, temperature, relative humidity, and carbon dioxide levels. In total, UFP count data were collected on 60 occasions in 37 occupied classrooms at one elementary school and one secondary school in Pembroke, Ontario. On average, outdoor UFP levels exceeded indoor measures by 8989 cm -3 (95% confidence interval (CI): 6382, 11 596), and classroom UFP counts were similar at both schools with a combined average of 5017 cm -3 (95% CI: 4300, 5734). Of the variables examined only wind speed and outdoor UFPs were important determinants of classrooms UFP levels. Specifically, each 10 km/h increase in wind speed corresponded to an 1873 cm -3 (95% CI: 825, 2920) decrease in classroom UFP counts, and each 10 000 cm -3 increase in outdoor UFPs corresponded to a 1550 cm -3 (95% CI: 930, 2171) increase in classroom UFP levels. However, high correlations between these two predictors meant that the independent effects of wind speed and outdoor UFPs could not be separated in multivariable models, and only outdoor UFP counts were included in the final predictive model. To evaluate model performance, classroom UFP counts were collected for 8 days at two new schools and compared to predicted values based on outdoor UFP measures. A moderate correlation was observed between measured and predicted classroom UFP counts (r=0.63) for both schools combined, but this relationship was not valid on days in which a strong indoor UFP

  11. Coarse and fine particles but nout ultrafine particles in urban air trigger hospital admission for asthma in children

    DEFF Research Database (Denmark)

    Iskander, A.; Andersen, Z.J.; Bønnelykke, K.

    2012-01-01

    .AimTo study whether short-term exposure to air pollution is associated with hospital admissions for asthma in children. It is hypothesised that (1) the association between asthma admissions and air pollution is stronger with UFPs than with coarse (PM(10)) and fine (PM(2.5)) particles, nitrogen oxides (NO...... association was found between hospital admissions for asthma in children aged 0-18 years and NO(x) (OR 1.11; 95% CI 1.05 to 1.17), NO(2) (1.10; 95% CI 1.04 to 1.16), PM(10) (1.07; 95% CI 1.03 to 1.12) and PM(2.5) (1.09; 95% CI 1.04 to 1.13); there was no association with UFPs. The association was stronger...

  12. Mixtures of Berkson and classical covariate measurement error in the linear mixed model: Bias analysis and application to a study on ultrafine particles.

    Science.gov (United States)

    Deffner, Veronika; Küchenhoff, Helmut; Breitner, Susanne; Schneider, Alexandra; Cyrys, Josef; Peters, Annette

    2018-03-13

    The ultrafine particle measurements in the Augsburger Umweltstudie, a panel study conducted in Augsburg, Germany, exhibit measurement error from various sources. Measurements of mobile devices show classical possibly individual-specific measurement error; Berkson-type error, which may also vary individually, occurs, if measurements of fixed monitoring stations are used. The combination of fixed site and individual exposure measurements results in a mixture of the two error types. We extended existing bias analysis approaches to linear mixed models with a complex error structure including individual-specific error components, autocorrelated errors, and a mixture of classical and Berkson error. Theoretical considerations and simulation results show, that autocorrelation may severely change the attenuation of the effect estimations. Furthermore, unbalanced designs and the inclusion of confounding variables influence the degree of attenuation. Bias correction with the method of moments using data with mixture measurement error partially yielded better results compared to the usage of incomplete data with classical error. Confidence intervals (CIs) based on the delta method achieved better coverage probabilities than those based on Bootstrap samples. Moreover, we present the application of these new methods to heart rate measurements within the Augsburger Umweltstudie: the corrected effect estimates were slightly higher than their naive equivalents. The substantial measurement error of ultrafine particle measurements has little impact on the results. The developed methodology is generally applicable to longitudinal data with measurement error. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. A main amplifier circuit and data acquisition system for charged particle detector array

    International Nuclear Information System (INIS)

    Hao Rui; Ge Yucheng

    2011-01-01

    The charged particle detector array has huge amounts of signal and needs high counting rate. To meet the requirements, a main amplifier and analog-to-digital conversion circuit based on high-speed op-amp chips and ADC chip was designed. A 51-MCU was used to control the circuit of ADC and the USB communication chip. The signals were digitized and uploaded by the MCU-ADC-USB circuit. The whole system has a compact hardware structure and a reasonable controlling software, which meet the design requirements. (authors)

  14. Electrochemical behavior of copper metal core/oxide shell ultra-fine particles on mercury electrodes in aqueous dispersions

    Czech Academy of Sciences Publication Activity Database

    Korshunov, A.; Heyrovský, Michael

    2009-01-01

    Roč. 629, 1-2 (2009), s. 23-29 ISSN 0022-0728 R&D Projects: GA ČR GA203/07/1195; GA AV ČR IAA400400806 Institutional research plan: CEZ:AV0Z40400503 Keywords : ultrafine copper powders * surface oxide layers * aqueous dispersions * voltammetry * Hg electrodes Subject RIV: CG - Electrochemistry Impact factor: 2.580, year: 2007

  15. Electrode geometry effects on the collection efficiency of submicron and ultra-fine dust particles in spike-plate electrostatic precipitators

    International Nuclear Information System (INIS)

    Brocilo, D; Podlinski, J; Chang, J S; Mizeraczyk, J; Findlay, R D

    2008-01-01

    The collection efficiency of electrostatic precipitators for the submicron particles ranging from 0.1 to 1 μm and ultrafine particles smaller than 0. lμm is below the requirements of new PM2.5 emission regulations. In this work, numerical and experimental studies were conducted to examine the effect of discharge and collecting electrode geometries on the ion density and electric field profiles and consequently their effect on the particle surface charge and collection efficiency. The collection efficiency prediction was based on a modified Deutsche's equation after calculation of three dimensional electric field and ion density profiles. Whereas, the particle surface charge was obtained from diffusion and field charging models. Results show that the collection efficiency of fine particles for the spike-type discharge electrode when compared to the conventional wire-type was improved. Experimental validations were conducted on a bench scale electrostatic precipitator for total and partial collection efficiency of particles ranging in size from 0.01 to 20 μm and the results indicated that the model can be effectively applied for prototype design, modification, and scale-up of collecting and discharge electrodes.

  16. Co-formation of hydroperoxides and ultra-fine particles during the reactions of ozone with a complex VOC mixture under simulated indoor conditions

    DEFF Research Database (Denmark)

    Fan, Z.H.; Weschler, Charles J.; Han, IK

    2005-01-01

    In this study we examined the co-formation of hydrogen peroxide and other hydroperoxides (collectively presented as H2O2*) as well as submicron particles, including ultra-fine particles (UFP), resulting from the reactions of ozone (O-3) with a complex mixture of volatile organic compounds (VOCs...... higher than typical indoor levels. When O-3 was added to a 25-m(3) controlled environmental facility (CEF) containing the 23 VOC mixture, both H2O2* and submicron particles were formed. The 2-h average concentration of H2O2* was 1.89 +/- 0.30ppb, and the average total particle number concentration was 46...... to achieve saturated concentrations of the condensable organics. When the 2 terpenes were removed from the O-3/23 VOCs mixture, no H2O2* or particles were formed, indicating that the reactions of O-3 With the two terpenes were the key processes contributing to the formation of H2O2* and submicron particles...

  17. Outdoor fine and ultrafine particle measurements at six bus stops with smoking on two California arterial highways--results of a pilot study.

    Science.gov (United States)

    Ott, Wayne R; Acevedo-Bolton, Viviana; Cheng, Kai-Chung; Jiang, Ruo-Ting; Klepeis, Neil E; Hildemann, Lynn M

    2014-01-01

    As indoor smoking bans have become widely adopted, some U.S. communities are considering restricting smoking outdoors, creating a need for measurements of air pollution near smokers outdoors. Personal exposure experiments were conducted with four to five participants at six sidewalk bus stops located 1.5-3.3 m from the curb of two heavily traveled California arterial highways with 3300-5100 vehicles per hour. At each bus stop, a smoker in the group smoked a cigarette. Gravimetrically calibrated continuous monitors were used to measure fine particle concentrations (aerodynamic diameter bus stop, ultrafine particles (UFP), wind speed, temperature, relative humidity, and traffic counts were also measured. For 13 cigarette experiments, the mean PM2.5 personal exposure of the nonsmoker seated 0.5 m from the smoker during a 5-min cigarette ranged from 15 to 153 microg/m3. Of four persons seated on the bench, the smoker received the highest PM2.5 breathing-zone exposure of 192 microg/m3. There was a strong proximity effect: nonsmokers at distances 0.5, 1.0, and 1.5 m from the smoker received mean PM2.5 personal exposures of 59, 40, and 28 microg/m3, respectively, compared with a background level of 1.7 microg/m3. Like the PM2.5 concentrations, UFP concentrations measured 0.5 m from the smoker increased abruptly when a cigarette started and decreased when the cigarette ended, averaging 44,500 particles/cm3 compared with the background level of 7200 particles/cm3. During nonsmoking periods, the UFP background concentrations showed occasional peaks due to traffic, whereas PM2.5 background concentrations were extremely low. The results indicate that a single cigarette smoked outdoors at a bus stop can cause PM2.5 and UFP concentrations near the smoker that are 16-35 and 6.2 times, respectively, higher than the background concentrations due to cars and trucks on an adjacent arterial highway. Rules banning smoking indoors have been widely adopted in the United States and in

  18. Seasonal and spatial variation of trace elements and metals in quasi-ultrafine (PM0.25) particles in the Los Angeles metropolitan area and characterization of their sources

    International Nuclear Information System (INIS)

    Saffari, Arian; Daher, Nancy; Shafer, Martin M.; Schauer, James J.; Sioutas, Constantinos

    2013-01-01

    Year-long sampling campaign of quasi-ultrafine particles (PM 0.25 ) was conducted at 10 distinct locations across the Los Angeles south coast air basin and concentrations of trace elements and metals were quantified at each site using high-resolution inductively coupled plasma sector field mass spectrometry. In order to characterize sources of trace elements and metals, principal component analysis (PCA) was applied to the dataset. The major sources were identified as road dust (influenced by vehicular emissions as well as re-suspended soil), vehicular abrasion, residual oil combustion, cadmium sources and metal plating. These sources altogether accounted for approximately 85% of the total variance of quasi-ultrafine elemental content. The concentrations of elements originating from source and urban locations generally displayed a decline as we proceeded from the coast to the inland. Occasional concentration peaks in the rural receptor sites were also observed, driven by the dominant westerly/southwesterly wind transporting the particles to the receptor areas. -- Highlights: •We collected quasi-ultrafine samples at 10 locations across the Los Angeles Basin. •The concentration of trace elements and metals at each site were quantified. •Distinct temporal and spatial variability was observed across the basin. •Principal component analysis was applied to the data to characterize the sources. •Five major sources were identified for quasi-ultrafine elemental content. -- Characterization of sources of trace elements and metals in quasi-ultrafine particles in the Los Angeles south coast air basin and explaining their seasonal and spatial variability

  19. Short-term exposure to PM 10, PM 2.5, ultrafine particles and CO 2 for passengers at an intercity bus terminal

    Science.gov (United States)

    Cheng, Yu-Hsiang; Chang, Hsiao-Peng; Hsieh, Cheng-Ju

    2011-04-01

    The Taipei Bus Station is the main transportation hub for over 50 bus routes to eastern, central, and southern Taiwan. Daily traffic volume at this station is about 2500 vehicles, serving over 45,000 passengers daily. The station is a massive 24-story building housing a bus terminal, a business hotel, a shopping mall, several cinemas, offices, private residential suites, and over 900 parking spaces. However, air quality inside this bus terminal is a concern as over 2500 buses are scheduled to run daily. This study investigates the PM 10, PM 2.5, UFP and CO 2 levels inside and outside the bus terminal. All measurements were taken between February and April 2010. Measurement results show that coarse PM inside the bus terminal was resuspended by the movement of large numbers of passengers. The fine and ultrafine PM in the station concourse were from outside vehicles. Moreover, fine and ultrafine PM at waiting areas were exhausted directly from buses in the building. The CO 2 levels at waiting areas were likely elevated by bus exhaust and passengers exhaling. The PM 10, PM 2.5 and CO 2 levels at the bus terminal were lower than Taiwan's EPA suggested standards for indoor air quality. However, UFP levels at the bus terminal were significantly higher than those in the urban background by about 10 times. Therefore, the effects of UFPs on the health of passengers and workers must be addressed at this bus terminal since the levels of UFPs are higher than >1.0 × 10 5 particles cm -3.

  20. Microstructural evolution and magnetic properties of ultrafine solute-atom particles formed in a Cu75-Ni20-Fe5 alloy on isothermal annealing

    Science.gov (United States)

    Kim, Jun-Seop; Takeda, Mahoto; Bae, Dong-Sik

    2016-12-01

    Microstructural features strongly affect magnetism in nano-granular magnetic materials. In the present work we have investigated the relationship between the magnetic properties and the self-organized microstructure formed in a Cu75-Ni20-Fe5 alloy comprising ferromagnetic elements and copper atoms. High resolution transmission electron microscopy (HRTEM) observations showed that on isothermal annealing at 873 K, nano-scale solute (Fe,Ni)-rich clusters initially formed with a random distribution in the Cu-rich matrix. Superconducting quantum interference device (SQUID) measurements revealed that these ultrafine solute clusters exhibited super-spinglass and superparamagnetic states. On further isothermal annealing the precipitates evolved to cubic or rectangular ferromagnetic particles and aligned along the directions of the copper-rich matrix. Electron energy-band calculations based on the first-principle Korringa-Kohn-Rostocker (KKR) method were also implemented to investigate both the electronic structure and the magnetic properties of the alloy. Inputting compositions obtained experimentally by scanning transmission electron microscopy-electron dispersive X-ray spectroscopy (STEM-EDS) analysis, the KKR calculation confirmed that ferromagnetic precipitates (of moment 1.07μB per atom) formed after annealing for 2 × 104 min. Magneto-thermogravimetric (MTG) analysis determined with high sensitivity the Curie temperatures and magnetic susceptibility above room temperature of samples containing nano-scale ferromagnetic particles.

  1. Applicability of a two-step laser desorption-ionization aerosol time-of-flight mass spectrometer for determination of chemical composition of ultrafine aerosol particles

    Energy Technology Data Exchange (ETDEWEB)

    Laitinen, T.

    2013-11-01

    This thesis is based on the construction of a two-step laser desorption-ionization aerosol time-of-flight mass spectrometer (laser AMS), which is capable of measuring 10 to 50 nm aerosol particles collected from urban and rural air at-site and in near real time. The operation and applicability of the instrument was tested with various laboratory measurements, including parallel measurements with filter collection/chromatographic analysis, and then in field experiments in urban environment and boreal forest. Ambient ultrafine aerosol particles are collected on a metal surface by electrostatic precipitation and introduced to the time-of-flight mass spectrometer (TOF-MS) with a sampling valve. Before MS analysis particles are desorbed from the sampling surface with an infrared laser and ionized with a UV laser. The formed ions are guided to the TOF-MS by ion transfer optics, separated according to their m/z ratios, and detected with a micro channel plate detector. The laser AMS was used in urban air studies to quantify the carbon cluster content in 50 nm aerosol particles. Standards for the study were produced from 50 nm graphite particles, suspended in toluene, with 72 hours of high power sonication. The results showed the average amount of carbon clusters (winter 2012, Helsinki, Finland) in 50 nm particles to be 7.2% per sample. Several fullerenes/fullerene fragments were detected during the measurements. In boreal forest measurements, the laser AMS was capable of detecting several different organic species in 10 to 50 nm particles. These included nitrogen-containing compounds, carbon clusters, aromatics, aliphatic hydrocarbons, and oxygenated hydrocarbons. A most interesting event occurred during the boreal forest measurements in spring 2011 when the chemistry of the atmosphere clearly changed during snow melt. On that time concentrations of laser AMS ions m/z 143 and 185 (10 nm particles) increased dramatically. Exactly at the same time, quinoline concentrations

  2. Hygroscopic properties of ultrafine aerosol particles in the boreal forest: diurnal variation, solubility and the influence of sulfuric acid

    Directory of Open Access Journals (Sweden)

    M. Ehn

    2007-01-01

    Full Text Available The hygroscopic growth of aerosol particles present in a boreal forest was measured at a relative humidity of 88%. Simultaneously the gas phase concentration of sulfuric acid, a very hygroscopic compound, was monitored. The focus was mainly on days with new particle formation by nucleation. The measured hygroscopic growth factors (GF correlated positively with the gaseous phase sulfuric acid concentrations. The smaller the particles, the stronger the correlation, with r=0.20 for 50 nm and r=0.50 for 10 nm particles. The increase in GF due to condensing sulfuric acid is expected to be larger for particles with initially smaller masses. During new particle formation, the changes in solubility of the new particles were calculated during their growth to Aitken mode sizes. As the modal diameter increased, the solubility of the particles decreased. This indicated that the initial particle growth was due to more hygroscopic compounds, whereas the later growth during the evening and night was mainly caused by less hygroscopic or even hydrophobic compounds. For all the measured sizes, a diurnal variation in GF was observed both during days with and without particle formation. The GF was lowest at around midnight, with a mean value of 1.12–1.24 depending on particle size and if new particle formation occurred during the day, and increased to 1.25–1.34 around noon. This can be tentatively explained by day- and nighttime gas-phase chemistry; different vapors will be present depending on the time of day, and through condensation these compounds will alter the hygroscopic properties of the particles in different ways.

  3. Spatial and seasonal variations of the chemical, mineralogical and morphological features of quasi-ultrafine particles (PM{sub 0.49}) at urban sites

    Energy Technology Data Exchange (ETDEWEB)

    Samara, Constantini, E-mail: csamara@chem.auth.gr [Department of Chemistry, Environmental Pollution Control Laboratory, Aristotle University, GR-54124 Thessaloniki (Greece); Kantiranis, Nikolaos; Kollias, Panagiotis [Department of Geology, Division of Mineralogy-Petrology-Economic Geology, Aristotle University, GR-54124 Thessaloniki (Greece); Planou, Styliani; Kouras, Athanasios; Besis, Athanasios; Manoli, Evangelia; Voutsa, Dimitra [Department of Chemistry, Environmental Pollution Control Laboratory, Aristotle University, GR-54124 Thessaloniki (Greece)

    2016-05-15

    Combining chemical and physical-structural information of particles is a key issue in PM investigations. Chemical, mineralogical, and morphological characterization of quasi-ultrafine particles (PM{sub 0.49}) was carried out at two urban sites of varying traffic-influence (roadside and urban background) in Thessaloniki, northern Greece, during the cold and the warm period of 2013. Bulk analyses of chemical species included organic and elemental carbon (OC, EC), water soluble organic carbon (WSOC), ionic species (NO{sub 3}{sup −}, SO{sub 4}{sup 2−}, Cl{sup −}, Na{sup +}, NH{sub 4}{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}) and trace elements (As, Ba, Cd, Cr, Cu, Fe, Pb, Mn, Ni, Zn, Pt, Pd, Rh, Ru, and Ir). X-ray diffractometry (XRD) was employed for the mineralogical analysis of PM{sub 0.49} in order to identify and quantify amorphous and crystalline phases. In addition, scanning electron microscopy coupled with energy dispersive spectrometry (SEM-EDS) was employed for morphological characterization and elemental microanalysis of individual particles. Findings of this work could provide the basis for designing epidemiological and toxicity studies to mitigate population exposure to UFPs. - Highlights: • Chemical, mineralogical, and morphological features of PM{sub 0.49} were investigated. • PM{sub 0.49} levels were highest at the traffic site during wintertime. • PM{sub 0.49} mass was dominated by OM, minerals, EC and secondary ions. • Chemical mass closure showed significant seasonal and spatial variations. • Mineralogical composition was dominated by the organic amorphous phase.

  4. Investigations of percutaneous uptake of ultrafine TiO{sub 2} particles at the high energy ion nanoprobe LIPSION

    Energy Technology Data Exchange (ETDEWEB)

    Menzel, F. E-mail: fmenzel@physik.uni-leipzig.de; Reinert, T.; Vogt, J.; Butz, T

    2004-06-01

    Micronised TiO{sub 2} particles with a diameter of about 15 nm are used in sunscreens as physical UV filter. Due to the small particle size it may be supposed that TiO{sub 2} particles can pass through the uppermost horny skin layer (stratum corneum) via intercellular channels and penetrate into deeper vital skin layers. Accumulations of TiO{sub 2} particles in the skin can decrease the threshold for allergies of the immune system or cause allergic reactions directly. Spatially resolved ion beam analysis (PIXE, RBS, STIM and secondary electron imaging) was carried out on freeze-dried cross-sections of biopsies of pig skin, on which four different formulations containing TiO{sub 2} particles were applied. The investigations were carried out at the high energy ion nanoprobe LIPSION in Leipzig with a 2.25 MeV proton beam, which was focused to a diameter of 1 {mu}m. The analysis concentrated on the penetration depth and on pathways of the TiO{sub 2} particles into the skin. In these measurements a penetration of TiO{sub 2} particles through the s. corneum into the underlying stratum granulosum via intercellular space was found. Hair follicles do not seem to be important penetration pathways because no TiO{sub 2} was detected inside. The TiO{sub 2} particle concentration in the stratum spinosum was below the minimum detection limit of about 1 particle/{mu}m{sup 2}. These findings show the importance of coating the TiO{sub 2} particles in order to prevent damage of RNA and DNA of skin cells by photocatalytic reactions of the penetrated particles caused by absorption of UV light.

  5. Investigations of percutaneous uptake of ultrafine TiO2 particles at the high energy ion nanoprobe LIPSION

    International Nuclear Information System (INIS)

    Menzel, F.; Reinert, T.; Vogt, J.; Butz, T.

    2004-01-01

    Micronised TiO 2 particles with a diameter of about 15 nm are used in sunscreens as physical UV filter. Due to the small particle size it may be supposed that TiO 2 particles can pass through the uppermost horny skin layer (stratum corneum) via intercellular channels and penetrate into deeper vital skin layers. Accumulations of TiO 2 particles in the skin can decrease the threshold for allergies of the immune system or cause allergic reactions directly. Spatially resolved ion beam analysis (PIXE, RBS, STIM and secondary electron imaging) was carried out on freeze-dried cross-sections of biopsies of pig skin, on which four different formulations containing TiO 2 particles were applied. The investigations were carried out at the high energy ion nanoprobe LIPSION in Leipzig with a 2.25 MeV proton beam, which was focused to a diameter of 1 μm. The analysis concentrated on the penetration depth and on pathways of the TiO 2 particles into the skin. In these measurements a penetration of TiO 2 particles through the s. corneum into the underlying stratum granulosum via intercellular space was found. Hair follicles do not seem to be important penetration pathways because no TiO 2 was detected inside. The TiO 2 particle concentration in the stratum spinosum was below the minimum detection limit of about 1 particle/μm 2 . These findings show the importance of coating the TiO 2 particles in order to prevent damage of RNA and DNA of skin cells by photocatalytic reactions of the penetrated particles caused by absorption of UV light

  6. A land use regression model for ambient ultrafine particles in Montreal, Canada: A comparison of linear regression and a machine learning approach.

    Science.gov (United States)

    Weichenthal, Scott; Ryswyk, Keith Van; Goldstein, Alon; Bagg, Scott; Shekkarizfard, Maryam; Hatzopoulou, Marianne

    2016-04-01

    Existing evidence suggests that ambient ultrafine particles (UFPs) (regression model for UFPs in Montreal, Canada using mobile monitoring data collected from 414 road segments during the summer and winter months between 2011 and 2012. Two different approaches were examined for model development including standard multivariable linear regression and a machine learning approach (kernel-based regularized least squares (KRLS)) that learns the functional form of covariate impacts on ambient UFP concentrations from the data. The final models included parameters for population density, ambient temperature and wind speed, land use parameters (park space and open space), length of local roads and rail, and estimated annual average NOx emissions from traffic. The final multivariable linear regression model explained 62% of the spatial variation in ambient UFP concentrations whereas the KRLS model explained 79% of the variance. The KRLS model performed slightly better than the linear regression model when evaluated using an external dataset (R(2)=0.58 vs. 0.55) or a cross-validation procedure (R(2)=0.67 vs. 0.60). In general, our findings suggest that the KRLS approach may offer modest improvements in predictive performance compared to standard multivariable linear regression models used to estimate spatial variations in ambient UFPs. However, differences in predictive performance were not statistically significant when evaluated using the cross-validation procedure. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

  7. Analysis of the chemical composition of ultrafine particles from two domestic solid biomass fired room heaters under simulated real-world use

    Science.gov (United States)

    Ozgen, Senem; Becagli, Silvia; Bernardoni, Vera; Caserini, Stefano; Caruso, Donatella; Corbella, Lorenza; Dell'Acqua, Manuela; Fermo, Paola; Gonzalez, Raquel; Lonati, Giovanni; Signorini, Stefano; Tardivo, Ruggero; Tosi, Elisa; Valli, Gianluigi; Vecchi, Roberta; Marinovich, Marina

    2017-02-01

    Two common types of wood (beech and fir) were burned in commercial pellet (11.1 kW) and wood (8.2 kW) stoves following a combustion cycle simulating the behavior of a real-world user. Ultrafine particulate matter (UFP, dp pellets and wood UFP samples, where high TC levels characterize the wood log combustion and potassium salts are dominant in every pellet sample. Crucial aspects determining the UFP composition in the wood stove experiments are critical situations in terms of available oxygen (a lack or an excess of combustion air) and high temperatures. Whereas for the automatically controlled pellets stove local situations (e.g., hindered air-fuel mixing due to heaps of pellets on the burner pot) determine the emission levels and composition. Wood samples contain more potentially carcinogenic PAHs with respect to pellets samples. Some diagnostic ratios related to PAH isomers and anhydrosugars compiled from experimental UFP data in the present study and compared to literature values proposed for the emission source discrimination for atmospheric aerosol, extend the evaluation usually limited to higher particle size fractions also to UFP.

  8. The formation of ultra-fine particles during ozone-initiated oxidations with terpenes emitted from natural paint

    International Nuclear Information System (INIS)

    Lamorena, Rheo B.; Jung, Sang-Guen; Bae, Gwi-Nam; Lee, Woojin

    2007-01-01

    The formation of secondary products during the ozone-initiated oxidations with biogenic VOCs emitted from natural paint was investigated in this study. Mass spectrometry and infrared spectroscopy measurements have shown that the major components of gas-phase chemicals emitted from natural paint are monoterpenes including α- and β-pinenes, camphene, p-cymene, and limonene. A significant formation of gaseous carbonyl products and nano-sized particles (4.4-168 nm) was observed in the presence of ozone. Carboxylic acids were also observed to form during the reactions (i.e. formic acid at 0.170 ppm and acetic acid at 0.260 ppm). The formation of particles increased as the volume of paint introduced into a reaction chamber increased. A secondary increase in the particle number concentration was observed after 440 min, which suggests further partitioning of oxidation products (i.e. carboxylic acids) into the particles previously existing in the reaction chamber. The growth of particles increased as the mean particle diameter and particle mass concentrations increased during the reaction. The experimental results obtained in this study may provide insight into the potential exposure of occupants to irritating chemical compounds formed during the oxidations of biogenic VOCs emitted from natural paint in indoor environments

  9. Comprehensive Characterization Of Ultrafine Particulate Emission From 2007 Diesel Engines: PM Size Distribution, Loading And Indidividual Particle Size And Composition.

    Science.gov (United States)

    Zelenyuk, A.; Cuadra-Rodriguez, L. A.; Imre, D.; Shimpi, S.; Warey, A.

    2006-12-01

    The strong absorption of solar radiation by black carbon (BC) impacts the atmospheric radiative balance in a complex and significant manner. One of the most important sources of BC is vehicular emissions, of which diesel represents a significant fraction. To address this issue the EPA has issues new stringent regulations that will be in effect in 2007, limiting the amount of particulate mass that can be emitted by diesel engines. The new engines are equipped with aftertreatments that reduce PM emissions to the point, where filter measurements are subject to significant artifacts and characterization by other techniques presents new challenges. We will present the results of the multidisciplinary study conducted at the Cummins Technical Center in which a suite of instruments was deployed to yield comprehensive, temporally resolved information on the diesel exhaust particle loadings and properties in real-time: Particle size distributions were measured by Engine Exhaust Particle Sizer (EEPS) and Scanning Mobility Particle Sizer (SMPS). Total particle diameter concentration was obtained using Electrical Aerosol Detector (EAD). Laser Induced Incandescence and photoacoustic techniques were used to monitor the PM soot content. Single Particle Laser Ablation Time-of- flight Mass Spectrometer (SPLAT) provided the aerodynamic diameter and chemical composition of individual diesel exhaust particles. Measurements were conducted on a number of heavy duty diesel engines operated under variety of operating conditions, including FTP transient cycles, ramped-modal cycles and steady states runs. We have also characterized PM emissions during diesel particulate filter regeneration cycles. We will present a comparison of PM characteristics observed during identical cycles, but with and without the use of aftertreatment. A total of approximately 100,000 individual particles were sized and their composition characterized by SPLAT. The aerodynamic size distributions of the characterized

  10. A fast large dynamic range shaping amplifier for particle detector front-end

    International Nuclear Information System (INIS)

    Rivetti, Angelo; Delaurenti, Paolo

    2007-01-01

    The paper describes a fast shaping amplifier with rail-to-rail output swing. The circuit is based on a CMOS operational amplifier with a class AB output stage. A baseline holder, incorporating a closed-loop unity gain buffer with slew rate limitation, performs the AC coupling with the preamplifier and guarantees a baseline shift smaller than 3 mV for unipolar output pulses of 3 V and 10 MHz rate

  11. Real-world emission factors of fine and ultrafine aerosol particles for different traffic situations in Switzerland.

    Science.gov (United States)

    Imhof, David; Weingartner, Ernest; Ordónez, Carlos; Gehrig, Robert; Hill, Matz; Buchmann, Brigitte; Baltensperger, Urs

    2005-11-01

    Extended field measurements of particle number (size distribution of particle diameters, D, in the range between 18 nm and 10 microm), surface area concentrations, and PM1 and PM10 mass concentrations were performed in Switzerland to determine traffic emissions using a comprehensive set of instruments. Measurements took place at roads with representative traffic regimes: at the kerbside of a motorway (120 km h(-1)), a highway (80-100 km h(-1)), and in an urban area with stop-and-go traffic (0-50 km h(-1)) regulated by light signals. Mean diurnal variations showed that the highest pollutant concentrations were during the morning rush hours, especially of the number density in the nanoparticle size range (D real-life" emission factors were derived using NOx concentrations to calculate dilution factors. Particle number and volume emission factors of different size ranges (18-50 nm, 18-100 nm, and 18-300 nm) were derived for the total vehicle fleet and separated into a light-duty (LDV) and a heavy-duty vehicle (HDV) contribution. The total particle number emissions per vehicle were found to be about 11.7-13.5 x 10(14) particles km(-1) for constant speed (80-120 km h(-1) and 3.9 x 10(14) particles km(-1) for urban driving conditions. LDVs showed higher emission factors at constant high speed than under urban disturbed traffic flow. In contrast, HDVs emitted more air pollutants during deceleration and acceleration processes in stop-and-go traffic than with constant speed of about 80 km h(-1). On average, one HDV emits a 10-30 times higher amount of particulate air pollutants (in terms of both number and volume) than one LDV.

  12. Seasonal variations of ultra-fine and submicron aerosols in Taipei, Taiwan: implications for particle formation processes in a subtropical urban area

    Directory of Open Access Journals (Sweden)

    H. C. Cheung

    2016-02-01

    Full Text Available The aim of this study is to investigate the seasonal variations in the physicochemical properties of atmospheric ultra-fine particles (UFPs, d ≤ 100 nm and submicron particles (PM1, d ≤ 1 µm in an east Asian urban area, which are hypothesized to be affected by the interchange of summer and winter monsoons. An observation experiment was conducted at TARO (Taipei Aerosol and Radiation Observatory, an urban aerosol station in Taipei, Taiwan, from October 2012 to August 2013. The measurements included the mass concentration and chemical composition of UFPs and PM1, as well as the particle number concentration (PNC and the particle number size distribution (PSD with size range of 4–736 nm. The results indicated that the mass concentration of PM1 was elevated during cold seasons with a peak level of 18.5 µg m−3 in spring, whereas the highest concentration of UFPs was measured in summertime with a mean of 1.64 µg m−3. Moreover, chemical analysis revealed that the UFPs and PM1 were characterized by distinct composition; UFPs were composed mostly of organics, whereas ammonium and sulfate were the major constituents of PM1. The seasonal median of total PNCs ranged from 13.9  ×  103 cm−3 in autumn to 19.4  ×  103 cm−3 in spring. Median concentrations for respective size distribution modes peaked in different seasons. The nucleation-mode PNC (N4 − 25 peaked at 11.6  ×  103 cm−3 in winter, whereas the Aitken-mode (N25 − 100 and accumulation-mode (N100 − 736 PNC exhibited summer maxima at 6.0  ×  103 and 3.1  ×  103 cm−3, respectively. The change in PSD during summertime was attributed to the enhancement in the photochemical production of condensable organic matter that, in turn, contributed to the growth of aerosol particles in the atmosphere. In addition, clear photochemical production of particles was observed, mostly in the summer season

  13. Ternary blend with synergistic action of elastomeric and rigid polymer inclusions; comparison of vulcanized and reactively compatibilized ultrafine rubber particles

    Czech Academy of Sciences Publication Activity Database

    Kelnar, Ivan; Kotek, Jiří; Munteanu, B. S.; Qiao, J.; Kaprálková, Ludmila

    2005-01-01

    Roč. 25, č. 2 (2005), s. 175-185 ISSN 0334-6447 R&D Projects: GA ČR GA106/01/0601 Keywords : toughness * crosslinked rubber particles * poly amide 6 Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.312, year: 2005

  14. Experimental Study on Ultrafine Particle Removal Performance of Portable Air Cleaners with Different Filters in an Office Room

    Directory of Open Access Journals (Sweden)

    Huan Ma

    2016-01-01

    Full Text Available Size- and time-dependent aerodynamic behaviors of indoor particles, including PM1.0, were evaluated in a school office in order to test the performance of air-cleaning devices using different filters. In-situ real-time measurements were taken using an optical particle counter. The filtration characteristics of filter media, including single-pass efficiency, volume and effectiveness, were evaluated and analyzed. The electret filter (EE medium shows better initial removal efficiency than the high efficiency (HE medium in the 0.3–3.5 μm particle size range, while under the same face velocity, the filtration resistance of the HE medium is several times higher than that of the EE medium. During service life testing, the efficiency of the EE medium decreased to 60% with a total purifying air flow of 25 × 104 m3/m2. The resistance curve rose slightly before the efficiency reached the bottom, and then increased almost exponentially. The single-pass efficiency of portable air cleaner (PAC with the pre-filter (PR or the active carbon granule filter (CF was relatively poor. While PAC with the pre-filter and the high efficiency filter (PR&HE showed maximum single-pass efficiency for PM1.0 (88.6%, PAC with the HE was the most effective at removing PM1.0. The enhancement of PR with HE and electret filters augmented the single-pass efficiency, but lessened the airflow rate and effectiveness. Combined with PR, the decay constant of large-sized particles could be greater than for PACs without PR. Without regard to the lifetime, the electret filters performed better with respect to resource saving and purification improvement. A most penetrating particle size range (MPPS: 0.4–0.65 μm exists in both HE and electret filters; the MPPS tends to become larger after HE and electret filters are combined with PR. These results serve to provide a better understanding of the indoor particle removal performance of PACs when combined with different kinds of filters in

  15. Design and simulation of Gaussian shaping amplifier made only with CMOS FET for FEE of particle detector

    International Nuclear Information System (INIS)

    Wembe Tafo Evariste; Su Hong; Qian Yi; Kong Jie; Wang Tongxi

    2010-01-01

    The objective of this paper is to design and simulate a shaping amplifier circuit for silicon strip, Si (Li), CdZnTe and CsI detectors, etc., which can be further integrated the whole system and adopted to develop CMOS-based application, specific integrated circuit for Front End Electronics (FEE) of read-out system of nuclear physics, particle physics and astrophysics research, etc. It's why we used only CMOS transistor to develop the entire system. A Pseudo-Gaussian shaping amplifier made by fourth-order integration stage and a differentiation stage give a result same as a true CR-RC 4 filter, we perform shaping time in the range, 465 ns to 2.76μs with a low output resistance and the linearity almost good. (authors)

  16. [Oxidative Stress Derived from Airborne Fine and Ultrafine Particles and the Effects on Brain-Nervous System: Part 2].

    Science.gov (United States)

    Sagai, Masaru; Tin Win-Shwe, Tin

    2015-01-01

    Traffic-related air pollution is a major contributor to urban air pollution. Diesel exhaust (DE) is its most important component of near-road and urban air pollutions and is commonly used as a surrogate model of air pollution in health effects studies. In particular, diesel exhaust particles (DEPs) and nanoparticles in DEPs are the components considered hazardous for health. It is widely known that exposure to DEPs is associated with mortality caused by respiratory and cardiovascular diseases. Recently, evidence has been accumulating showing that DEPs and nanoparticles may cause neurodegenerative disorders. Here, we introduce evidence suggesting their association with these disorders. The chemical components and the translocation of DEPs and nanoparticles to the brain are described in part 1. In part 2, we introduce the mechanism of development of neurodegenerative diseases such as stroke, Alzheimer's disease, and Parkinson's disease via oxidative stress and inflammatory events. Furthermore, there are many lines of epidemiological evidence showing that the particulates impair cognitive function and ability of memory through oxidative and inflammatory events in the brain. These lines of evidences are supported by many animal experiments on neurological disorders.

  17. [Oxidative stress derived from airborne fine and ultrafine particles and the effects on brain-nervous system: part 1].

    Science.gov (United States)

    Sagai, Masaru; Win-Shwe, Tin Tin

    2015-01-01

    Traffic-related air pollution is a major contributor to urban air pollution. Diesel exhaust (DE) is the most important component of near-road and urban air pollution and is commonly used as a surrogate model of air pollution in health effects studies. In particular, diesel exhaust particles (DEP) and the nanoparticles in DEP are considered hazardous components on health effects. It is widely known that exposure to DEP is associated with mortality due to respiratory and cardiovascular diseases. Recently, there has been accumulating evidence that DEP and the nanoparticles in DEP may be causes of neurodegenerative disorders. Here, we introduce the evidence suggesting their association with such disorders. First, we describe the chemical components and the translocation of DEP and nanoparticles to the brain, and then introduce the evidence and a mechanism by which reactive oxygen species (ROS) and any inflammatory mediators can be produced by DEP phagocytosis of macrophages, microglia and astrocyte cells in the brain. There are many lines of evidence showing that the neurodegenerative disorders are profoundly associated with enhanced oxidative and inflammatory events. Second, we describe a mechanism by which neurodegenerative diseases, such as stroke, Alzheimer's disease and Parkinson's disease, are induced via oxidative stress and inflammatory events.

  18. Laboratory evaluation of the particle size effect on the performance of an elastomeric half-mask respirator against ultrafine combustion particles.

    Science.gov (United States)

    He, Xinjian; Grinshpun, Sergey A; Reponen, Tiina; Yermakov, Michael; McKay, Roy; Haruta, Hiroki; Kimura, Kazushi

    2013-08-01

    This study quantified the particle size effect on the performance of elastomeric half-mask respirators, which are widely used by firefighters and first responders exposed to combustion aerosols. One type of elastomeric half-mask respirator equipped with two P-100 filters was donned on a breathing manikin while challenged with three combustion aerosols (originated by burning wood, paper, and plastic). Testing was conducted with respirators that were fully sealed, partially sealed (nose area only), or unsealed to the face of a breathing manikin to simulate different faceseal leakages. Three cyclic flows with mean inspiratory flow (MIF) rates of 30, 85, and 135 L/min were tested for each combination of sealing condition and combustion material. Additional testing was performed with plastic combustion particles at other cyclic and constant flows. Particle penetration was determined by measuring particle number concentrations inside and outside the respirator with size ranges from 20 to 200 nm. Breathing flow rate, particle size, and combustion material all had significant effects on the performance of the respirator. For the partially sealed and unsealed respirators, the penetration through the faceseal leakage reached maximum at particle sizes >100 nm when challenged with plastic aerosol, whereas no clear peaks were observed for wood and paper aerosols. The particles aerosolized by burning plastic penetrated more readily into the unsealed half-mask than those aerosolized by the combustion of wood and paper. The difference may be attributed to the fact that plastic combustion particles differ from wood and paper particles by physical characteristics such as charge, shape, and density. For the partially sealed respirator, the highest penetration values were obtained at MIF = 85 L/min. The unsealed respirator had approximately 10-fold greater penetration than the one partially sealed around the bridge of the nose, which indicates that the nose area was the primary leak

  19. Quality of skin as a barrier to ultra-fine particles. Contribution of the IBA group to the NANODERM EU-5 project in 2003-2004

    International Nuclear Information System (INIS)

    Kertesz, Zs.; Szikszai, Z.; Kiss, A.Z.

    2004-01-01

    Complete text of publication follows. Micronised titanium-, zinc- or silicon-oxide is a widely used physical photoprotective agent as a component of various cosmetic products. Due to the small particle size (down to 15 nm) it is supposed, that the particles may pass through the uppermost horny skin layer, and penetrate into deeper vital skin layers. However, only a few experiments have been carried out on its penetration through the human epidermal barrier and its possible biological effects in vivo and in vitro, using the tape stripping method which has no lateral and limited depth resolution. A consortium consisting of 12 European universities and scientific institutes has been established under the leadership of the Fakultat fuer Physik und Geowissenchaft Universitat Leipzig, whose goal is to get quantitative information on the penetration of ultrafine particles in all strata of skin, on their penetration pathways as well as on their impact on human health [1]. The IBA group of the Atomki takes part in this project as a subcontractor of the Department of Dermatology, University of Debrecen, Hungary. Ion microscopy, electron microscopy and autoradiography are used to trace the penetration of the nanoparticles into the skin layers, molecular and cell-biological methods are applied to assess the skin response and activation of dermal cells. The IBA group of the Atomki takes part in WP3: Ion Microscopy Work Package together with five other nuclear microprobe laboratories. The participants provide quantitative elemental composition in all strata of skin with detection limits of about 1 μg/g and lateral resolution of 1-2 μm by applying various ion beam analytical techniques. Samples investigated by ion microscopy are 14-16 μm thick cryo-fixed freeze-dried sections of porcine and human skin. Since the sample preparation requires completely different treatment for ion microscopy than for conventional microscopy, the members of the IBA group, who already have

  20. Preparation and Characterization of Plasma-Sprayed Ultrafine Chromium Oxide Coatings

    International Nuclear Information System (INIS)

    Lin Feng; Jiang Xianliang; Yu Yueguang; Zeng Keli; Ren Xianjing; Li Zhenduo

    2007-01-01

    Ultrafine chromium oxide coatings were prepared by plasma spraying with ultrafine feedstock. Processing parameters of plasma spraying were optimized. Optical microscope (OM) was used to observe the microstructure of the ultrafine chromium oxide coatings. Scanning electron microscopy (SEM) was used to observe the morphology and particle size of ultrafine powder feedstock as well as to examine the microstructure of the chromium oxide coating. In addition, hardness and bonding strength of the ultrafine chromium oxide coatings were measured. The results showed that the optimized plasma spraying parameters were suitable for ultrafine chromium oxide coating and the properties and microstructure of the optimized ultrafine chromium oxide coating were superior compared to conventional chromium oxide wear resistant coatings

  1. Calculation of the output power in self-amplified spontaneous radiation using scaling of power with number of simulation particles

    International Nuclear Information System (INIS)

    Yu, L.H.

    1998-01-01

    Recent advances in self-amplified spontaneous emission (SASE) experiments stimulate interest in quantitative comparison of measurements with theory. In this paper we show that the widely used simulation code TDA3D, developed by Tran and Wurtele [Comput. Phys. Commun. 54, 263 (1989)] even though a single frequency code, can be used to determine the output power in the SASE process with excellent approximation in the exponential growth regime. The method applies when the gain is not very high, which is a special advantage, because when the gain is not very high, the analytical calculation is particularly difficult since the exponential growing term does not dominate. The analysis utilizes a scaling relation between the output power and the number of simulation particles in the code TDA3D: left-angle P right-angle=N λ ' /N λ left-angle P ' right-angle, where left-angle P right-angle is the output power and N λ is the line density of the electrons, while left-angle P ' right-angle is the calculated output power using a line density N λ ' of the number of simulation particles in the code TDA3D. Because of the scaling property, the number of simulation particles can be taken to be many orders of magnitude less than the actual experiment. Comparison of our results with experiment yields new insight into the SASE process. copyright 1998 The American Physical Society

  2. Ultrafine ash aerosols from coal combustion: Characterization and health effects

    Energy Technology Data Exchange (ETDEWEB)

    William P. Linak; Jong-Ik Yoo; Shirley J. Wasson; Weiyan Zhu; Jost O.L. Wendt; Frank E. Huggins; Yuanzhi Chen; Naresh Shah; Gerald P. Huffman; M. Ian Gilmour [US Environmental Protection Agency, Research Triangle Park, NC (United States). National Risk Management Research Laboratory

    2007-07-01

    Ultrafine coal fly-ash particles withdiameters less than 0.5 {mu}m typically comprise less than 1% of the total fly-ash mass. This paper reports research focused on both characterization and health effects of primary ultrafine coal ash aerosols alone. Ultrafine, fine, and coarse ash particles were segregated and collected from a coal burned in a 20 kW laboratory combustor and two additional coals burned in an externally heated drop tube furnace. Extracted samples from both combustors were characterized by transmission electron microscopy (TEM), wavelength dispersive X-ray fluorescence(WD-XRF) spectroscopy, Moessbauer spectroscopy, and X-ray absorption fine structure (XAFS) spectroscopy. Pulmonary inflammation was characterized by albumin concentrations in mouse lung lavage fluid after instillation of collected particles in saline solutions and a single direct inhalation exposure. Results indicate that coal ultrafine ash sometimes contains significant amounts of carbon, probably soot originating from coal tar volatiles, depending on coal type and combustion device. Surprisingly, XAFS results revealed the presence of chromium and thiophenic sulfur in the ultrafine ash particles. The instillation results suggested potential lung injury, the severity of which could be correlated with the carbon (soot) content of the ultrafines. This increased toxicity is consistent with theories in which the presence of carbon mediates transition metal (i.e., Fe) complexes, as revealed in this work by TEM and XAFS spectroscopy, promoting reactive oxygenspecies, oxidation-reduction cycling, and oxidative stress. 24 refs., 7 figs.

  3. The association between the incidence of postmenopausal breast cancer and concentrations at street-level of nitrogen dioxide and ultrafine particles.

    Science.gov (United States)

    Goldberg, Mark S; Labrèche, France; Weichenthal, Scott; Lavigne, Eric; Valois, Marie-France; Hatzopoulou, Marianne; Van Ryswyk, Keith; Shekarrizfard, Maryam; Villeneuve, Paul J; Crouse, Daniel; Parent, Marie-Élise

    2017-10-01

    There is scant information as to whether traffic-related air pollution is associated with the incidence of breast cancer. Nitrogen dioxide (NO 2 ) and ultrafine particles (UFPs, variations in traffic-related air pollution and may also be associated with incidence. We conducted a population-based, case-control study of street-level concentrations of NO 2 and UFPs and incident postmenopausal breast cancer in Montreal, Canada. Incident cases were identified between 2008 and 2011 from all but one hospital that treated breast cancer in the Montreal area. Population controls were identified from provincial electoral lists of Montreal residents and frequency-matched to cases using 5-year age groups. Concentrations of NO 2 and UFPs were estimated using two separate land-use regression models. Exposures were assigned to residential locations at the time of recruitment, and we identified residential histories of women who had lived in these residences for 10 years or more. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using logistic regression models adjusting for individual-level and ecological covariates. We assessed the functional form of NO 2 and UFP exposures using natural cubic splines. We found that the functional form of the response functions between incident postmenopausal breast cancer and concentrations of NO 2 and UFPs were consistent with linearity. For NO 2 , we found increasing risks of breast cancer for all subjects combined and stronger associations when analyses were restricted to those women who had lived at their current address for 10 years or more. Specifically, the OR, adjusted for personal covariates, per increase in the interquartile range (IQR=3.75 ppb) of NO 2 was 1.08 (95%CI: 0.92-1.27). For women living in their homes for 10 years or more, the adjusted OR was 1.17 (95%CI: 0.93-1.46; IQR=3.84 ppb); for those not living at that home 10 years before the study, it was 0.93 (95%CI: 0.64, 1.36; IQR=3.65 ppb). For UFPs, the ORs were

  4. Laplace transform method in analysing the effect of amplifier parameter on identification of light charged particles with CsI(Tl) + PD (photodiodes) detector

    International Nuclear Information System (INIS)

    Wang Jinchuan; Xi Hongfei; Guo Zhongyan; Zhan Wenlong; Zhu Yongtai; Zhou Jianqun; Liu Guanhua; Su Hong

    1992-01-01

    Laplace transform method is applied to investigate the effect of the choice of amplifier parameter on identification of the light charged particles emitted from 12 C(46.7 MeV/u) + 58 Ni reaction. The significance of application of Laplace transformation method in heavy ion experimental nuclear physics is discussed as well

  5. Amplified CPEs enhancement of chorioamnion membrane mass transport by encapsulation in nano-sized PLGA particles.

    Science.gov (United States)

    Azagury, Aharon; Amar-Lewis, Eliz; Appel, Reut; Hallak, Mordechai; Kost, Joseph

    2017-08-01

    Chemical penetration enhancers (CPEs) have long been used for mass transport enhancement across membranes. Many CPEs are used in a solution or gel and could be a solvent. The use of CPEs is mainly limited due to their toxicity/irritation levels. This study presents the evaluation of encapsulated CPEs in nano-sized polymeric particles on the chorioamnion (CA) membrane mass transport. CPEs' mass encapsulated in nanoparticles was decreased by 10,000-fold. Interestingly, this approach resulted in a 6-fold increase in mass transport across the CA. This approach may also be used with other CPEs' base applications necessitating lower CPE concentration. Applying Ultrasound (US) has shown to increase the release rate of and also the mass transport across the CA membrane. It is proposed that encapsulated CPEs penetrate into the CA membrane thus prolonging their exposure, possibly extending their penetration into the CA membrane, while insonation also deepens their penetration into the CA membrane. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Preparation of ultrafine iron particles by chemical vapor deposition of Fe(CO) sub 5. Fe(CO) sub 5 wo gebryo to suru kiso kagaku hanno ni yoru tetsuchobiryushi no seisei

    Energy Technology Data Exchange (ETDEWEB)

    Sawada, Y; Kageyama, Y. (Mitsubishi Petrochemical Co. Ltd., Tokyo (Japan)): Iwata, M. (Nagoya University, Nagoya (Japan). Faculty of Engineering)

    1991-11-10

    An ultrafine iron particle preparing process was developed, which wses gaseous phase pyrolysis in magnetic field of iron pentacarbonyl, Fe(CO){sub 5}, based on the fact that Fe(CO){sub 5} has peculiar characters that its boiling point is as low as 103{degree}C, and starts decomposing in a low temperature zone of 100{degree}C or lower. Vaporizing and introducing into a reactor an fe(CO){sub 5}, andPyrolyzing it at 200-600{degree}C while being diluted with nitrogen and applied with a magnetic field produced uitrafine iron particles of a necklace-like chain comprisinh primary particles having diameter of 15 to 25 nm with 10 to 40 of them linked in a straight chain. It was found that the specific surface area is 30-50 m{sup 2}/g, with the diameter converted from the specific surface area being relatively close to the average diameter obtained from TEM photograph, and that the particle has few pores. Magnetically the iron powder has a coercivity of 123-131 KA/m and a specific saturation magnetization of 120-140 Am{sup 2}/kg, and is expected to be applied as a high density magnetic recording medium. 5 refs.,8 figs., 3 tabs.

  7. Fiber Amplifiers

    DEFF Research Database (Denmark)

    Rottwitt, Karsten

    2017-01-01

    The chapter provides a discussion of optical fiber amplifiers and through three sections provides a detailed treatment of three types of optical fiber amplifiers, erbium doped fiber amplifiers (EDFA), Raman amplifiers, and parametric amplifiers. Each section comprises the fundamentals including...... the basic physics and relevant in-depth theoretical modeling, amplifiers characteristics and performance data as a function of specific operation parameters. Typical applications in fiber optic communication systems and the improvement achievable through the use of fiber amplifiers are illustrated....

  8. Preparation and pattern recognition of metallic Ni ultrafine powders by electroless plating

    International Nuclear Information System (INIS)

    Zhang, H.J.; Zhang, H.T.; Wu, X.W.; Wang, Z.L.; Jia, Q.L.; Jia, X.L.

    2006-01-01

    Using hydrazine hydrate as reductant, metallic Ni ultrafine powders were prepared from NiSO 4 aqueous solution by electroless plating method. The factors including concentration of NiSO 4 , bathing temperature, ratio of hydrazine hydrate to NiSO 4 , the pH of the solution, etc., on influence of the yield and average particle size of metallic Ni ultrafine powders were studied in detail. X-ray powders diffraction patterns show that the nickel powders are cubic crystallite. The average crystalline size of the ultrafine nickel powders is about 30 nm. The dielectric and magnetic loss of ultrafine Ni powders-paraffin wax composites were measured by the rectangle waveguide method in the range 8.2-12.4 GHz. The factors for Ni ultrafine powders preparation are optimized by computer pattern recognition program based on principal component analysis, the optimum factors regions with higher yield of metallic Ni ultrafine powders are indicated by this way

  9. EFFECT OF CENTRAL FANS AND IN-DUCT FILTERS ON DEPOSITION RATES OF ULTRAFINE AND FINE PARTICLES IN AN OCCUPIED TOWNHOUSE

    Science.gov (United States)

    Airborne particles are implicated in morbidity and mortality of certain high-risk subpopulations. Exposure to particles occurs mostly indoors, where a main removal mechanism is deposition to surfaces. Deposition can be affected by the use of forced- air circulation through duct...

  10. Variability of Black Carbon and Ultrafine Particle Concentration on Urban Bike Routes in a Mid-Sized City in the Po Valley (Northern Italy

    Directory of Open Access Journals (Sweden)

    Giovanni Lonati

    2017-02-01

    Full Text Available Cyclists might experience increased air pollution exposure, due to the proximity to traffic, and higher intake, due to their active travel mode and higher ventilation. Several local factors, like meteorology, road and traffic features, and bike lanes features, affect cyclists’ exposure to traffic-related pollutants. This paper investigates the concentration levels and the effect of the features of the bike lanes on cyclists’ exposure to airborne ultrafine particulate matter (UFP and black carbon (BC in the mid-sized city of Piacenza, located in the middle of the Po Valley, Northern Italy. Monitoring campaigns were performed by means of portable instruments along different urban bike routes with bike lanes, characterized by different distances from the traffic source (on-road cycle lane, separated cycle lane, green cycle path, during morning (9:00 am–10:00 am and evening (17:30 pm–18:30 pm workday rush hours in both cold and warm seasons. The proximity to traffic significantly affected cyclists’ exposure to UFP and BC: exposure concentrations measured for the separated lane and for the green path were 1–2 times and 2–4 times lower than for the on-road lane. Concurrent measurements showed that exposure concentrations to PM10, PM2.5, and PM1 were not influenced by traffic proximity, without any significant variation between on-road cycle lane, separated lane, or green cycle path. Thus, for the location of this study PM mass-based metrics were not able to capture local scale concentration gradients in the urban area as a consequence of the rather high urban and regional background that hides the contribution of local scale sources, such as road traffic. The impact of route choice on cyclists’ exposure to UFPs and BC during commuting trips back and forth from a residential area to the train station has been also estimated through a probabilistic approach through an iterative Monte Carlo technique, based on the measured data. Compared

  11. In-vehicle measurement of ultrafine particles on compressed natural gas, conventional diesel, and oxidation-catalyst diesel heavy-duty transit buses.

    Science.gov (United States)

    Hammond, Davyda; Jones, Steven; Lalor, Melinda

    2007-02-01

    Many metropolitan transit authorities are considering upgrading transit bus fleets to decrease ambient criteria pollutant levels. Advancements in engine and fuel technology have lead to a generation of lower-emission buses in a variety of fuel types. Dynamometer tests show substantial reductions in particulate mass emissions for younger buses (vehicle particle number concentration measurements on conventional diesel, oxidation-catalyst diesel and compressed natural gas transit buses are compared to estimate relative in-vehicle particulate exposures. Two primary consistencies are observed from the data: the CNG buses have average particle count concentrations near the average concentrations for the oxidation-catalyst diesel buses, and the conventional diesel buses have average particle count concentrations approximately three to four times greater than the CNG buses. Particle number concentrations are also noticeably affected by bus idling behavior and ventilation options, such as, window position and air conditioning.

  12. Spatial and indoor/outdoor gradients in urban concentrations of ultrafine particles and PM2.5 mass and chemical components

    Science.gov (United States)

    Zauli Sajani, Stefano; Ricciardelli, Isabella; Trentini, Arianna; Bacco, Dimitri; Maccone, Claudio; Castellazzi, Silvia; Lauriola, Paolo; Poluzzi, Vanes; Harrison, Roy M.

    2015-02-01

    In order to investigate relationships between outdoor air pollution and concentrations indoors, a novel design of experiment has been conducted at two sites, one heavily trafficked and the other residential. The novel design aspect involves the introduction of air directly to the centre of an unoccupied room by use of a fan and duct giving a controlled air exchange rate and allowing an evaluation of particle losses purely due to uptake on indoor surfaces without the losses during penetration of the building envelope which affect most measurement programmes. The rooms were unoccupied and free of indoor sources, and consequently reductions in particle concentration were due to deposition processes within the room alone. Measurements were made of indoor and outdoor concentrations of PM2.5, major chemical components and particle number size distributions. Despite the absence of penetration losses, indoor to outdoor ratios were very similar to those in other studies showing that deposition to indoor surfaces is likely to be the major loss process for indoor air. The results demonstrated a dramatic loss of nitrate in the indoor atmosphere as well as a selective loss of particles in the size range below 50 nm, in comparison to coarser particles. Depletion of indoor particles was greater during a period of cold weather with higher outdoor concentrations probably due to an enhancement of semi-volatile materials in the outdoor particulate matter. Indoor/outdoor ratios for PM2.5 were generally higher at the trafficked site than the residential site, but for particle number were generally lower, reflecting the different chemical composition and size distributions of particles at the two sites.

  13. Operation amplifier

    NARCIS (Netherlands)

    Tetsuya, Saito; Nauta, Bram

    2008-01-01

    To provide an operation amplifier which improves power source voltage removal ratios while assuring phase compensation characteristics, and therefore can be realized with a small-scale circuit and low power consumption. SOLUTION: The operation amplifier comprises: a differential amplifier circuit 1;

  14. Ultrafine particle levels at an international port of entry between the US and Mexico: exposure implications for users, workers, and neighbors.

    Science.gov (United States)

    Olvera, Hector A; Lopez, Mario; Guerrero, Veronica; Garcia, Humberto; Li, Wen-Whai

    2013-01-01

    Exposure to diesel-emitted particles has been linked to increased cancer risk and cardiopulmonary diseases. Because of their size (risks than those associated with larger particles. Seasonal UFP levels at the International Bridge of the Americas, which connects the US and Mexico and has high HDDV traffic demands, were characterized. Hourly average UFP concentrations ranged between 1.7 × 10(3)/cc and 2.9 × 10(5)/cc with a mean of 3.5 × 10(4)/cc. Wind speeds <2 m s(-1) and temperatures <15 °C were associated with particle number concentrations above normal conditions. The presence of HDDV had the strongest impact on local UFP levels. Varying particle size distributions were associated with south- and northbound HDDV traffic. Peak exposure occurred on weekday afternoons. Although in winter, high exposure episodes were also observed in the morning. Particle number concentrations were estimated to reach background levels at 400 m away from traffic. The populations exposed to UFP above background levels include law enforcement officers, street vendors, private commuters, and commercial vehicle drivers as well as neighbors on both sides of the border, including a church and several schools.

  15. Size distribution and total number concentration of ultrafine and accumulation mode particles and hospital admissions in children and the elderly in Copenhagen, Denmark

    DEFF Research Database (Denmark)

    Andersen, Zorana Jovanovic; Wåhlin, Peter; Raaschou-Nielsen, O

    2008-01-01

    (15 May 2001 to 31 December 2004) and hospital admissions due to cardiovascular (CVD) and respiratory disease (RD) in the elderly (age >or=65 years), and due to asthma in children (age 5-18 years). We examined these associations in the presence of PM(10), PM(2.5) (particulate matter ... that particle volume/mass from long-range transported air pollution is relevant for CVD and RD admissions in the elderly, and possibly particle numbers from traffic sources for paediatric asthma....

  16. Inducing Strong Density Modulation with Small Energy Dispersion in Particle Beams and the Harmonic Amplifier Free Electron Laser

    CERN Document Server

    McNeil, Brian W J; Robb, Gordon

    2005-01-01

    We present a possible method of inducing a periodic density modulation in a particle beam with little increase in the energy dispersion of the particles. The flow of particles in phase space does not obey Liouville's Theorem. The method relies upon the Kuramoto-like model of collective synchronism found in free electron generators of radiation, such as Cyclotron Resonance Masers and the Free Electron Laser. For the case of an FEL interaction, electrons initially begin to bunch and emit radiation energy with a correlated energy dispersion which is periodic with the FEL ponderomotive potential. The relative phase between potential and particles is then changed by approximately 180 degrees. The particles continue to bunch, however, there is now a correlated re-absorption of energy from the field. We show that, by repeating this relative phase change many times, a significant density modulation of the particles may be achieved with only relatively small energy dispersion. A similar method of repeated relative ele...

  17. Vascular and lung function related to ultrafine and fine particles exposure assessed by personal and indoor monitoring: a cross-sectional study

    DEFF Research Database (Denmark)

    Olsen, Yulia; Karottki, Dorina Gabriela; Jensen, Ditte Marie

    2014-01-01

    -related effects. Methods: Associations between vascular and lung function, inflammation markers and exposure in terms of particle number concentration (PNC; d = 10-300 nm) were studied in a cross-sectional design with personal and home indoor monitoring in the Western Copenhagen Area, Denmark. During 48-h, PNC...... and PM2.5 were monitored in living rooms of 60 homes with 81 non-smoking subjects (30-75 years old), 59 of whom carried personal monitors both when at home and away from home. We measured lung function in terms of the FEV1/FVC ratio, microvascular function (MVF) and pulse amplitude by digital artery...... tonometry, blood pressure and biomarkers of inflammation including C-reactive protein, and leukocyte counts with subdivision in neutrophils, eosinophils, monocytes, and lymphocytes in blood. Results: PNC from personal and stationary home monitoring showed weak correlation (r = 0.15, p = 0.24). Personal UFP...

  18. Temporal evolution of ultrafine particles and of alveolar deposited surface area from main indoor combustion and non-combustion sources in a model room.

    Science.gov (United States)

    Manigrasso, Maurizio; Vitali, Matteo; Protano, Carmela; Avino, Pasquale

    2017-11-15

    Aerosol number size distributions, PM mass concentrations, alveolar deposited surface areas (ADSAs) and VOC concentrations were measured in a model room when aerosol was emitted by sources frequently encountered in indoor environments. Both combustion and non-combustion sources were considered. The most intense aerosol emission occurred when combustion sources were active (as high as 4.1×10 7 particlescm -3 for two meat grilling sessions; the first with exhaust ventilation, the second without). An intense spike generation of nucleation particles occurred when appliances equipped with brush electric motors were operating (as high as 10 6 particlescm -3 on switching on an electric drill). Average UFP increments over the background value were highest for electric appliances (5-12%) and lowest for combustion sources (as low as -24% for tobacco cigarette smoke). In contrast, average increments in ADSA were highest for combustion sources (as high as 3.2×10 3 μm 2 cm -3 for meat grilling without exhaust ventilation) and lowest for electric appliances (20-90μm 2 cm -3 ). The health relevance of such particles is associated to their ability to penetrate cellular structures and elicit inflammatory effects mediated through oxidative stress in a way dependent on their surface area. The highest VOC concentrations were measured (PID probe) for cigarette smoke (8ppm) and spray air freshener (10ppm). The highest PM mass concentration (PM 1 ) was measured for citronella candle burning (as high as 7.6mgm -3 ). Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Influence of Ultrafine 2CaO·SiO₂ Powder on Hydration Properties of Reactive Powder Concrete.

    Science.gov (United States)

    Sun, Hongfang; Li, Zishanshan; Memon, Shazim Ali; Zhang, Qiwu; Wang, Yaocheng; Liu, Bing; Xu, Weiting; Xing, Feng

    2015-09-17

    In this research, we assessed the influence of an ultrafine 2CaO·SiO₂ powder on the hydration properties of a reactive powder concrete system. The ultrafine powder was manufactured through chemical combustion method. The morphology of ultrafine powder and the development of hydration products in the cement paste prepared with ultrafine powder were investigated by scanning electron microscopy (SEM), mineralogical composition were determined by X-ray diffraction, while the heat release characteristics up to the age of 3 days were investigated by calorimetry. Moreover, the properties of cementitious system in fresh and hardened state (setting time, drying shrinkage, and compressive strength) with 5% ordinary Portland cement replaced by ultrafine powder were evaluated. From SEM micrographs, the particle size of ultrafine powder was found to be up to several hundred nanometers. The hydration product started formulating at the age of 3 days due to slow reacting nature of belitic 2CaO·SiO₂. The initial and final setting times were prolonged and no significant difference in drying shrinkage was observed when 5% ordinary Portland cement was replaced by ultrafine powder. Moreover, in comparison to control reactive powder concrete, the reactive powder concrete containing ultrafine powder showed improvement in compressive strength at and above 7 days of testing. Based on above, it can be concluded that the manufactured ultrafine 2CaO·SiO₂ powder has the potential to improve the performance of a reactive powder cementitious system.

  20. Influence of Ultrafine 2CaO·SiO2 Powder on Hydration Properties of Reactive Powder Concrete

    Directory of Open Access Journals (Sweden)

    Hongfang Sun

    2015-09-01

    Full Text Available In this research, we assessed the influence of an ultrafine 2CaO·SiO2 powder on the hydration properties of a reactive powder concrete system. The ultrafine powder was manufactured through chemical combustion method. The morphology of ultrafine powder and the development of hydration products in the cement paste prepared with ultrafine powder were investigated by scanning electron microscopy (SEM, mineralogical composition were determined by X-ray diffraction, while the heat release characteristics up to the age of 3 days were investigated by calorimetry. Moreover, the properties of cementitious system in fresh and hardened state (setting time, drying shrinkage, and compressive strength with 5% ordinary Portland cement replaced by ultrafine powder were evaluated. From SEM micrographs, the particle size of ultrafine powder was found to be up to several hundred nanometers. The hydration product started formulating at the age of 3 days due to slow reacting nature of belitic 2CaO·SiO2. The initial and final setting times were prolonged and no significant difference in drying shrinkage was observed when 5% ordinary Portland cement was replaced by ultrafine powder. Moreover, in comparison to control reactive powder concrete, the reactive powder concrete containing ultrafine powder showed improvement in compressive strength at and above 7 days of testing. Based on above, it can be concluded that the manufactured ultrafine 2CaO·SiO2 powder has the potential to improve the performance of a reactive powder cementitious system.

  1. Operation Amplifier

    NARCIS (Netherlands)

    Tetsuya, Saito; Nauta, Bram

    2011-01-01

    PROBLEM TO BE SOLVED: To provide an operation amplifier which improves power source voltage removal ratios while assuring phase compensation characteristics, and therefore can be realized with a small-scale circuit and low power consumption. SOLUTION: The operation amplifier comprises: a

  2. Operation Amplifier

    NARCIS (Netherlands)

    Tetsuya, S.; Nauta, Bram

    2007-01-01

    PROBLEM TO BE SOLVED: To provide an operation amplifier which improves power source voltage removal ratios while assuring phase compensation characteristics, and therefore can be realized with a small-scale circuit and low power consumption. ; SOLUTION: The operation amplifier comprises: a

  3. Operational amplifiers

    CERN Document Server

    Dostal, Jiri

    1993-01-01

    This book provides the reader with the practical knowledge necessary to select and use operational amplifier devices. It presents an extensive treatment of applications and a practically oriented, unified theory of operational circuits.Provides the reader with practical knowledge necessary to select and use operational amplifier devices. Presents an extensive treatment of applications and a practically oriented, unified theory of operational circuits

  4. Amplifier Distortion

    Science.gov (United States)

    Keeports, David

    2006-12-01

    By definition, a high fidelity amplifier's instantaneous output voltage is directly proportional to its instantaneous input voltage. While high fidelity is generally valued in the amplification of recorded music, nonlinearity, also known as distortion, is desirable in the amplification of some musical instruments. In particular, guitar amplifiers exploit nonlinearity to increase both the harmonic content and sustain of a guitar's sound. I will discuss how both modifications in sound result from saturation of triode tubes and transistors. Additionally, I will describe the difference in the symmetry of saturation curves for transistors and tubes and the reason why tube guitar amplifiers are generally considered to be superior to solid-state amplifiers. Finally, I will discuss attempts to use solid-state electronics to replicate the sound of tube amplifiers.

  5. Contrast in air pollution components between major streets and background locations: Particulate matter mass, black carbon, elemental composition, nitrogen oxide and ultrafine particle number

    Science.gov (United States)

    Boogaard, Hanna; Kos, Gerard P. A.; Weijers, Ernie P.; Janssen, Nicole A. H.; Fischer, Paul H.; van der Zee, Saskia C.; de Hartog, Jeroen J.; Hoek, Gerard

    2011-01-01

    Policies to reduce outdoor air pollution concentrations are often assessed on the basis of the regulated pollutants. Whether these are the most appropriate components to assess the potential health benefits is questionable, as other health-relevant pollutants may be more strongly related to traffic. The aim of this study is to compare the contrast in concentration between major roads and (sub)urban background for a large range of pollutants and to analyze the magnitude of the measured difference in the street - background for major streets with different street configurations. Measurements of PM 10, PM 2.5, particle number concentrations (PNC), black carbon (BC), elemental composition of PM 10 and PM 2.5 and NO x were conducted simultaneously in eight major streets and nine (sub)urban background locations in the Netherlands. Measurements were done six times for a week during a six month period in 2008. High contrasts between busy streets and background locations in the same city were found for chromium, copper and iron (factor 2-3). These elements were especially present in the coarse fraction of PM. In addition, high contrasts were found for BC and NO x (factor 1.8), typically indicators of direct combustion emissions. The contrast for PNC was similar to BC. NO 2 contrast was lower (factor 1.5). The largest contrast was found for two street canyons and two streets with buildings at one side of the street only. The contrast between busy streets and urban background in NO 2 was less than the contrast found for BC, PNC and elements indicative of non-exhaust emissions, adding evidence that NO 2 is not representing (current) traffic well. The study supports a substantial role for non-exhaust emissions including brake- and tyre wear and road dust in addition to direct combustion emissions. Significant underestimation of disease burden may occur when relying too much on the regulated components.

  6. Fast pulse amplifier

    International Nuclear Information System (INIS)

    Lepetit, J.; Poussier, E.

    1984-01-01

    This amplifier comprises an inverter transformer, the primary circuit of which receives a pulse and the secondary circuit of which is connected to several amplifying elements in parallel. The inverter transformer is made of coaxial cable segments winded around a magnetic torus; the cable cores connected in series constitute the primary circuit and the braiding of cables, connected in parallel, are the secondary circuit. The transformer comprises, besides, delay lines in series with each braiding of the secondary circuit, these ones are such that pulses issued from each braiding arrive together to the secondary circuit connectors. This invention applies, noticeably in the case of a high voltage amplifier, to the control of deflection blocks of particles used in medicine or in particle accelerators [fr

  7. Protective effects of pulmonary epithelial lining fluid on oxidative stress and DNA single-strand breaks caused by ultrafine carbon black, ferrous sulphate and organic extract of diesel exhaust particles

    Energy Technology Data Exchange (ETDEWEB)

    Chuang, Hsiao-Chi [School of Respiratory Therapy, College of Medicine, Taipei Medical University, Taipei, Taiwan (China); Division of Pulmonary Medicine, Department of Internal Medicine, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan (China); Cheng, Yi-Ling; Lei, Yu-Chen [Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan (China); Chang, Hui-Hsien [Institute of Environmental Health, College of Public Health, National Taiwan University, Taipei, Taiwan (China); Cheng, Tsun-Jen, E-mail: tcheng@ntu.edu.tw [Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan (China); Department of Public Health, College of Public Health, National Taiwan University, Taipei, Taiwan (China)

    2013-02-01

    Pulmonary epithelial lining fluid (ELF) is the first substance to make contact with inhaled particulate matter (PM) and interacts chemically with PM components. The objective of this study was to determine the role of ELF in oxidative stress, DNA damage and the production of proinflammatory cytokines following physicochemical exposure to PM. Ultrafine carbon black (ufCB, 15 nm; a model carbonaceous core), ferrous sulphate (FeSO{sub 4}; a model transition metal) and a diesel exhaust particle (DEP) extract (a model organic compound) were used to examine the acellular oxidative potential of synthetic ELF and non-ELF systems. We compared the effects of exposure to ufCB, FeSO{sub 4} and DEP extract on human alveolar epithelial Type II (A549) cells to determine the levels of oxidative stress, DNA single-strand breaks and interleukin-8 (IL-8) production in ELF and non-ELF systems. The effects of ufCB and FeSO{sub 4} on the acellular oxidative potential, cellular oxidative stress and DNA single-strand breakage were mitigated significantly by the addition of ELF, whereas there was no decrease following treatment with the DEP extract. There was no significant effect on IL-8 production following exposure to samples that were suspended in ELF/non-ELF systems. The results of the present study indicate that ELF plays an important role in the initial defence against PM in the pulmonary environment. Experimental components, such as ufCB and FeSO{sub 4}, induced the production of oxidative stress and led to DNA single-strand breaks, which were moderately prevented by the addition of ELF. These findings suggest that ELF plays a protective role against PM-driven oxidative stress and DNA damage. -- Highlights: ► To determine the role of ELF in ROS, DNA damage and IL-8 after exposure to PM. ► ufCB, FeSO{sub 4} and DEP extract were used to examine the protective effects of ELF. ► PM-driven oxidative stress and DNA single-strand breakage were mitigated by ELF. ► The findings

  8. Preservation of amorphous ultrafine material: A proposed proxy for slip during recent earthquakes on active faults.

    Science.gov (United States)

    Hirono, Tetsuro; Asayama, Satoru; Kaneki, Shunya; Ito, Akihiro

    2016-11-09

    The criteria for designating an "Active Fault" not only are important for understanding regional tectonics, but also are a paramount issue for assessing the earthquake risk of faults that are near important structures such as nuclear power plants. Here we propose a proxy, based on the preservation of amorphous ultrafine particles, to assess fault activity within the last millennium. X-ray diffraction data and electron microscope observations of samples from an active fault demonstrated the preservation of large amounts of amorphous ultrafine particles in two slip zones that last ruptured in 1596 and 1999, respectively. A chemical kinetic evaluation of the dissolution process indicated that such particles could survive for centuries, which is consistent with the observations. Thus, preservation of amorphous ultrafine particles in a fault may be valuable for assessing the fault's latest activity, aiding efforts to evaluate faults that may damage critical facilities in tectonically active zones.

  9. Detection of Ultrafine Anaphase Bridges

    DEFF Research Database (Denmark)

    Bizard, Anna H; Nielsen, Christian F; Hickson, Ian D

    2018-01-01

    Ultrafine anaphase bridges (UFBs) are thin DNA threads linking the separating sister chromatids in the anaphase of mitosis. UFBs are thought to form when topological DNA entanglements between two chromatids are not resolved prior to anaphase onset. In contrast to other markers of defective...

  10. Ultrafine particle exposure in Danish residencies

    DEFF Research Database (Denmark)

    Bekö, Gabriel; Karottki, Dorina Gabriela; Wierzbicka, Aneta

    2016-01-01

    candle burning, cooking, toasting and unknown activities, were responsible on average for ∼65% of the residential integrated exposure. Residents of another 60 homes were then asked to carry a backpack equipped with a GPS recorder and a portable monitor to measure real-time individual exposure over ~48 h...... personal exposure, indoor environments other than home or vehicles contributed with ~40%, and being in transit or outdoors contributed 5% or less....

  11. Amplified Policymaking

    Science.gov (United States)

    Prince, Katherine; Woempner, Carolyn

    2010-01-01

    This brief examines the policy implications of two drivers of change presented in the "2020 Forecast: Creating the Future of Learning"-- Pattern Recognition and Amplified Organization. These drivers point toward a series of cultural shifts and illuminate how we are developing new ways of organizing, constructing, and managing knowledge.…

  12. Ultrafine hydrogen storage powders

    Science.gov (United States)

    Anderson, Iver E.; Ellis, Timothy W.; Pecharsky, Vitalij K.; Ting, Jason; Terpstra, Robert; Bowman, Robert C.; Witham, Charles K.; Fultz, Brent T.; Bugga, Ratnakumar V.

    2000-06-13

    A method of making hydrogen storage powder resistant to fracture in service involves forming a melt having the appropriate composition for the hydrogen storage material, such, for example, LaNi.sub.5 and other AB.sub.5 type materials and AB.sub.5+x materials, where x is from about -2.5 to about +2.5, including x=0, and the melt is gas atomized under conditions of melt temperature and atomizing gas pressure to form generally spherical powder particles. The hydrogen storage powder exhibits improved chemcial homogeneity as a result of rapid solidfication from the melt and small particle size that is more resistant to microcracking during hydrogen absorption/desorption cycling. A hydrogen storage component, such as an electrode for a battery or electrochemical fuel cell, made from the gas atomized hydrogen storage material is resistant to hydrogen degradation upon hydrogen absorption/desorption that occurs for example, during charging/discharging of a battery. Such hydrogen storage components can be made by consolidating and optionally sintering the gas atomized hydrogen storage powder or alternately by shaping the gas atomized powder and a suitable binder to a desired configuration in a mold or die.

  13. Effectiveness of the Top-Down Nanotechnology in the Production of Ultrafine Cement (~220 nm

    Directory of Open Access Journals (Sweden)

    Byung-Wan Jo

    2014-01-01

    Full Text Available The present investigation is dealing with the communition of the cement particle to the ultrafine level (~220 nm utilizing the bead milling process, which is considered as a top-down nanotechnology. During the grinding of the cement particle, the effect of various parameters such as grinding time (1–6 h and grinding agent (methanol and ethanol on the production of the ultrafine cement has also been investigated. Performance of newly produced ultrafine cement is elucidated by the chemical composition, particle size distribution, and SEM and XRD analyses. Based on the particle size distribution of the newly produced ultrafine cement, it was assessed that the size of the cement particle decreases efficiently with increase in grinding time. Additionally, it is optimized that the bead milling process is able to produce 90% of the cement particle <350 nm and 50% of the cement particle < 220 nm, respectively, after 6.3 h milling without affecting the chemical phases. Production of the ultrafine cement utilizing this method will promote the construction industries towards the development of smart and sustainable construction materials.

  14. Some characteristic features of the construction of the amplifying channel for working with semiconductor detectors in the charged particle energy spectrometer. [noise minimization at preamplifier input

    Science.gov (United States)

    Kuzyuta, E. I.

    1974-01-01

    A transistorized spectrometric amplifier with a shaper is reported that selects the shape of the frequency characteristic of the amplifying channel for which the primary frequency spectrum of the signal will pass, but where the noise spectrum is limited to the maximum. A procedure is presented for selecting the shaping circuits and their inclusion principles.

  15. Modification of the quantum-mechanical equations for the system of charged Dirac particles by including additional tensor terms of the Pauli type. Pt. 1. [Amplified Bethe-Salpeter, radiative corrections, fine structure

    Energy Technology Data Exchange (ETDEWEB)

    Janyszek, H [Uniwersytet Mikolaja Kopernika, Torun (Poland). Instytut Fizyki

    1974-01-01

    A new modified quasirelativistic equation (different from that of Breit) for N charged Dirac particles in the external stationary electromagnetic field is proposed. This equation is an amplified quantum-mechanical Bethe-Salpeter equation obtained by adding (in a semi-phenomenological manner) terms which take into account radiative corrections. The application of this approximate equations is limited to third order terms in the fine structure constant ..cap alpha...

  16. Ultrafine luminescent structures through nanoparticle self-assembly

    International Nuclear Information System (INIS)

    Prabhakaran, K; Goetzinger, S; Shafi, K V P M; Mazzei, A; Schietinger, S; Benson, O

    2006-01-01

    We report the fabrication of ultrafine structures consisting of regular arrays of nanoemitters through the self-assembly of luminescent nanoparticles on a silicon wafer. Nanoparticles of yttrium aluminium garnet (YAG) doped with Eu 3+ ions were synthesized by a sonochemical technique. These particles, suspended in ethanol, are introduced onto a pre-patterned silicon wafer, covered with a thin oxide layer. On annealing the sample in an ultrahigh-vacuum chamber, the nanoparticles self-assemble along the pattern. We demonstrate this 'chemical lithography' by assembling the nanoparticles along a variety of patterns. We believe that such self-organized nanopatterning of functional structures is important for the realization of nanodevices

  17. Synthesis and characterization of ultrafine well-dispersed magnetic nanoparticles

    International Nuclear Information System (INIS)

    Liu, Z.L.; Wang, H.B.; Lu, Q.H.; Du, G.H.; Peng, L.; Du, Y.Q.; Zhang, S.M.; Yao, K.L.

    2004-01-01

    Ultrafine well-dispersed magnetic nanoparticles were directly prepared in aqueous solution using controlled coprecipitation method. The structure, size, size distributions and magnetic properties of the magnetic nanoparticles, characterized by TEM, XRD and VSM, indicated the formation of single domain nanoparticles with average size smaller than 5 nm. The magnetic nanoparticles show superparamagnetism and a lower saturation magnetization is found as a consequence of smaller particle size. The relevant conditions for obtaining these magnetic colloids are discussed and the so-prepared magnetic nanoparticles are stable in a wide pH range

  18. A new and superior ultrafine cementitious grout

    International Nuclear Information System (INIS)

    Ahrens, E.H.

    1997-01-01

    Sealing fractures in nuclear waste repositories concerns all programs investigating deep burial as a means of disposal. Because the most likely mechanism for contaminant migration is by dissolution and movement through groundwater, sealing programs are seeking low-viscosity sealants that are chemically, mineralogically, and physically compatible with the host rock. This paper presents the results of collaborative work directed by Sandia National Laboratories (SNL) and supported by Whiteshell Laboratories, operated by Atomic Energy of Canada, Ltd. The work was undertaken in support of the Waste Isolation Pilot Plant (WIPP), an underground nuclear waste repository located in a salt formation east of Carlsbad, NM. This effort addresses the technology associated with long-term isolation of nuclear waste in a natural salt medium. The work presented is part of the WIPP plugging and sealing program, specifically the development and optimization of an ultrafine cementitious grout that can be injected to lower excessive, strain-induced hydraulic conductivity in the fractured rock termed the Disturbed Rock Zone (DRZ) surrounding underground excavations. Innovative equipment and procedures employed in the laboratory produced a usable cement-based grout; 90% of the particles were smaller than 8 microns and the average particle size was 4 microns. The process involved simultaneous wet pulverization and mixing. The grout was used for a successful in situ test underground at the WIPP. Injection of grout sealed microfractures as small as 6 microns (and in one rare instance, 3 microns) and lowered the gas transmissivity of the DRZ by up to three orders of magnitude. Following the WIPP test, additional work produced an improved version of the grout containing particles 90% smaller than 5 microns and averaging 2 microns. This grout will be produced in dry form, ready for the mixer

  19. Defect structure of ultrafine MgB2 nanoparticles

    International Nuclear Information System (INIS)

    Bateni, Ali; Somer, Mehmet; Repp, Sergej; Erdem, Emre; Thomann, Ralf; Acar, Selçuk

    2014-01-01

    Defect structure of MgB 2 bulk and ultrafine particles, synthesized by solid state reaction route, have been investigated mainly by the aid of X-band electron paramagnetic resonance spectrometer. Two different amorphous Boron (B) precursors were used for the synthesis of MgB 2 , namely, boron 95 (purity 95%–97%, <1.5 μm) and nanoboron (purity >98.5%, <250 nm), which revealed bulk and nanosized MgB 2 , respectively. Scanning and transmission electron microscopy analysis demonstrate uniform and ultrafine morphology for nanosized MgB 2 in comparison with bulk MgB 2 . Powder X-ray diffraction data show that the concentration of the by-product MgO is significantly reduced when nanoboron is employed as precursor. It is observed that a significant average particle size reduction for MgB 2 can be achieved only by using B particles of micron or nano size. The origin and the role of defect centers were also investigated and the results proved that at nanoscale MgB 2 material contains Mg vacancies. Such vacancies influence the connectivity and the conductivity properties which are crucial for the superconductivity applications

  20. ULTRAFINE FLUORESCENT DIAMONDS IN NANOTECHNOLOGY

    Directory of Open Access Journals (Sweden)

    Kanyuk M. I.

    2014-07-01

    Full Text Available The purpose of the work is to summarize the literature data concerning ultrafine diamonds, namely their industrial production, as well as considerable photostability and biocompatibility that promote their use in modern visualization techniques. It is shown that due to the unique physical properties, they are promising materials for using in nanotechnology in the near future. Possibility of diverse surface modification, small size and large absorption surface are the basis for their use in different approaches for drug and gene delivery into a cell. The changes in the properties of nanodiamond surface modification methods of their creation, stabilization and applications are described. It can be said that fluorescent surface-modified nanodiamonds are a promising target in various research methods that would be widely used for labeling of living cells, as well as in the processes of genes and drugs delivery into a cell.

  1. Ultracentrifugation for ultrafine nanodiamond fractionation

    Science.gov (United States)

    Koniakhin, S. V.; Besedina, N. A.; Kirilenko, D. A.; Shvidchenko, A. V.; Eidelman, E. D.

    2018-01-01

    In this paper we propose a method for ultrafine fractionation of nanodiamonds using the differential centrifugation in the fields up to 215000g. The developed protocols yield 4-6 nm fraction giving main contribution to the light scattering intensity. The desired 4-6 nm fraction can be obtained from various types of initial nanodiamonds: three types of detonation nanodiamonds differing in purifying methods, laser synthesis nanodiamonds and nanodiamonds made by milling. The characterization of the obtained hydrosols was conducted with Dynamic Light Scattering, Zeta potential measurements, powder XRD and TEM. According to powder XRD and TEM data ultracentrifugation also leads to a further fractionation of the primary diamond nanocrystallites in the hydrosols from 4 to 2 nm.

  2. Unraveling the atomic structure of ultrafine iron clusters

    KAUST Repository

    Wang, Hongtao; Li, Kun; Yao, Yingbang; Wang, Qingxiao; Cheng, Yingchun; Schwingenschlö gl, Udo; Zhang, Xixiang; Yang, Wei

    2012-01-01

    Unraveling the atomic structures of ultrafine iron clusters is critical to understanding their size-dependent catalytic effects and electronic properties. Here, we describe the stable close-packed structure of ultrafine Fe clusters for the first

  3. Ultrafine grained steels processed by equal channel angular pressing

    International Nuclear Information System (INIS)

    Shin, Dong Hyuk; Park, Kyung-Tae

    2005-01-01

    Recent development of ultrafine grained (UFG) low carbon steels by using equal channel angular pressing (ECAP) and their room temperature tensile properties are reviewed, focusing on the strategies overcoming their inherent mechanical drawbacks. In addition to ferrite grain refinement, when proper post heat treatments are imposed, carbon atom dissolution from pearlitic cementite during ECAP can be utilized for microstructural modification such as uniform distribution of nano-sized cementite particles or microalloying element carbides inside UFG ferrite grains and fabrication of UFG ferrite/martensite dual phase steel. The utilization of nano-sized particles is effective on improving thermal stability of UFG low carbon ferrite/pearlite steel but less effective on improving its tensile properties. By contrast, UFG ferrite/martensite dual phase steel exhibits an excellent combination of ultrahigh strength, large uniform elongation and extensive strain hardenability

  4. Adiabatic shear localization in ultrafine grained 6061 aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Bingfeng, E-mail: biw009@ucsd.edu [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Department of Mechanical and Aerospace Engineering, University of California, San Diego (United States); State Key Laboratory for Powder Metallurgy, Central South University, Changsha, Hunan (China); Key Lab of Nonferrous Materials, Ministry of Education, Central South University, Changsha 410083 (China); Ma, Rui; Zhou, Jindian [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Li, Zezhou; Zhao, Shiteng [Department of Mechanical and Aerospace Engineering, University of California, San Diego (United States); Huang, Xiaoxia [School of Materials Science and Engineering, Central South University, Changsha 410083 (China)

    2016-10-15

    Localized shear is an important mode of deformation; it leads to catastrophic failure with low ductility, and occurs frequently during high strain-rate deformation. The hat-shaped specimen has been successfully used to generate shear bands under controlled shock-loading tests. The microstructure in the forced shear band was characterized by optical microscopy, microhardness, and transmission electron microscopy. The true flow stress in the shear region can reach 800 MPa where the strain is about 2.2. The whole shear localization process lasts for about 100 μs. The shear band is a long and straight band distinguished from the matrix by boundaries. It can be seen that the grains in the boundary of the shear band are highly elongated along the shear direction and form the elongated cell structures (0.2 µm in width), and the core of the shear band consists of a number of recrystallized equiaxed grains with 0.2−0.3 µm in diameters, and the second phase particles distribute in the boundary of the ultrafine equiaxed new grains. The calculated temperature in the shear band can reach about 667 K. Finally, the formation of the shear band in the ultrafine grained 6061 aluminum alloy and its microstructural evolution are proposed.

  5. Production of ultrafine zinc powder from wastes containing zinc by electrowinning in alkaline solution

    Directory of Open Access Journals (Sweden)

    Zhao Youcai

    2013-12-01

    Full Text Available Production of ultrafine zinc powder from industrial wastes by electrowinning in alkaline solution was studied. Stainless steel and magnesium electrodes were used as anode and cathode, respectively. Morphology, size distribution and composition of the Zn particles were characterized by Scanning Electron Microscopy, Laser Particle Size Analyzer, and Inductive Coupled Plasma Emission Spectrometer. The required composition of the electrolyte for ultrafine particles was found to be 25-35 g/L Zn, 200-220 g/L NaOH and 20-40 mg/L Pb. The optimal conditions were a current density of 1000-1200 A/m² and an electrolyte temperature of 30-40 °C. The results indicated that the lead additive exerted a beneficial effect on the refining of the particles, by increasing the cathodic polarization. Through this study, ultrafine zinc powder with a size distribution of around 10 μm could be produced, and considerably high current efficiencies (97-99 % were obtained.

  6. Formation of fine particles in co-combustion of coal and solid recovered fuel in a pulverized coal-fired power station

    DEFF Research Database (Denmark)

    Wu, Hao; Pedersen, Anne Juul; Glarborg, Peter

    2011-01-01

    showed an ultrafine mode centered at approximately 0.1 μm. Compared with coal combustion, co-combustion of coal and SRF increased the formation of submicron particles, especially ultrafine particles below 0.2 μm. The morphology of the particles indicated that supermicron particles were primarily formed...... by the melting of minerals. The ultrafine particles were generated through nucleation and coagulation of vaporized inorganic species, while for the particles in between supermicron and ultrafine particles, condensation of vaporized species or aggregation of nucleates on the existing spherical submicron particles...... appear to be an important formation mechanism. The elemental composition of the particles from coal combustion showed that S and Ca were significantly enriched in ultrafine particles and P was also enriched considerably. However, compared with supermicron particles, the contents of Al, Si and K were...

  7. Deposition of ultrafine aerosols in F344/N rat nasal casts

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Y S; Hansen, G K; Su, Y F; Yeh, H C; Morgan, K T [Chemical Industry Institute of Toxicology, Research Triangle Park, NC (United States)

    1988-12-01

    Determination of regional respiratory deposition of inhaled aerosols is critical for evaluation of the health effects of air pollutants. Information on deposition of larger particles (> 0.02 {mu}m) in the nasal passages of laboratory animals is available; the deposition fraction increases with increasing particle size. Little information on ultrafine particles less than 0.2 {mu}m is available. Molds (models) were prepared from replica casts of the nasal passages of F344/N rats, using clear casting plastic. Total deposition of ultrafine aerosols in these casts was then determined using a unidirectional flow system. Measured pressure drops in the casts were a function of flow rate to the power of 1.4-1.6, indicating that the flow through the nasal passage was not laminar. Deposition data were obtained from these casts, using monodisperse sodium chloride aerosols with particle size ranging from 0.2 to 0.005 {mu}m, at inspiratory and expiratory flow rates of 200 to 600 cc/min. Similar deposition data were obtained for the three casts studied. The deposition efficiency was greatest for the smallest particles, and decreased with increasing particle size and flow rate, indicating that diffusion was the dominant mechanism for deposition. At an inspiratory flow rate of 400 cc/min, which is comparable to a respiratory minute volume of 200 cc/min for mature male F344/N rats, deposition efficiencies reached 40 and 70% for 0.01 and 0.005 {mu}m particles, respectively. Turbulent diffusion was considered to be the dominant mechanism for deposition of ultrafine particles in the nasal passage. This information is important for understanding the toxicity and carcinogenicity of submicrometer particles, including diesel soot, radon progeny and vapors. (author)

  8. Fatigue mechanisms in ultrafine-grained copper

    Czech Academy of Sciences Publication Activity Database

    Lukáš, Petr; Kunz, Ludvík; Svoboda, Milan

    2009-01-01

    Roč. 47, č. 1 (2009), s. 1-9 ISSN 0023-432X R&D Projects: GA AV ČR(CZ) 1QS200410502 Institutional research plan: CEZ:AV0Z20410507 Keywords : ultrafine-grained copper * effect of purity * effect of temperature Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.345, year: 2007

  9. Atmospheric ultrafine aerosol number concentration and its ...

    Indian Academy of Sciences (India)

    B. Pant Institute of Himalayan Environment & Development, Himachal Unit, ... a significant increase indicating impact of vehicular onslaught on pure air of this hilly region. 1. .... Meteorological conditions during ultrafine measurement days in 2008 at: (a) Mohal and ..... Claiborne C and Koenig J 1999 Episodes of high coarse.

  10. Ultrafine and Fine Particulate Matter Inside and Outside of Mechanically Ventilated Buildings.

    Science.gov (United States)

    Miller, Shelly L; Facciola, Nick A; Toohey, Darin; Zhai, John

    2017-01-28

    The objectives of this study were to measure levels of particulate matter (PM) in mechanically ventilated buildings and to improve understanding of filtration requirements to reduce exposure. With the use of an Ultra High Sensitivity Aerosol Spectrometer and an Aerodyne Mass Spectrometer, ultrafine (0.055-0.1 μm) and fine (0.1-0.7 μm) indoor and outdoor PM was measured as a function of time in an office, a university building, and two elementary schools. Indoor particle levels were highly correlated with outdoor levels. Indoor and outdoor number concentrations in Denver were higher than those in Boulder, with the highest number concentrations occurring during summer and fall. The ratio of indoor-to-outdoor (I/O) PM was weakly but positively correlated with the amount of ventilation provided to the indoor environment, did not vary much with particle size (ranged between 0.48 and 0.63 for the entire size range), and was similar for each period of the week (weekend vs. weekday, night vs. day). Regression analyses showed that ultrafine indoor PM baseline concentrations were higher at night from nighttime infiltration. A lag time was observed between outdoor and indoor measurements. Weekday days had the shortest lag time of 11 min, and weekend nighttime lags when the HVAC was not in use were 50 to 148 min. Indoor-outdoor PM concentration plots showed ultrafine PM was more correlated compared to fine, and especially when the HVAC system was on. Finally, AMS data showed that most of the PM was organic, with occasional nitrate events occurring outdoors. During nitrate events, there were less indoor particles detected, indicating a loss of particulate phase nitrate. The results from this study show that improved filtration is warranted in mechanically ventilated buildings, particularly for ultrafine particles, and that nighttime infiltration is significant depending on the building design.

  11. Pulmonary diseases induced by ambient ultrafine and engineered nanoparticles in twenty-first century.

    Science.gov (United States)

    Xia, Tian; Zhu, Yifang; Mu, Lina; Zhang, Zuo-Feng; Liu, Sijin

    2016-12-01

    Air pollution is a severe threat to public health globally, affecting everyone in developed and developing countries alike. Among different air pollutants, particulate matter (PM), particularly combustion-produced fine PM (PM 2.5 ) has been shown to play a major role in inducing various adverse health effects. Strong associations have been demonstrated by epidemiological and toxicological studies between increases in PM 2.5 concentrations and premature mortality, cardiopulmonary diseases, asthma and allergic sensitization, and lung cancer. The mechanisms of PM-induced toxicological effects are related to their size, chemical composition, lung clearance and retention, cellular oxidative stress responses and pro-inflammatory effects locally and systemically. Particles in the ultrafine range (ambient ultrafine particles have higher toxic potential compared with PM 2.5 . In addition, the rapid development of nanotechnology, bringing ever-increasing production of nanomaterials, has raised concerns about the potential human exposure and health impacts. All these add to the complexity of PM-induced health effects that largely remains to be determined, and mechanistic understanding on the toxicological effects of ambient ultrafine particles and nanomaterials will be the focus of studies in the near future.

  12. Amplifier for nuclear spectrometry

    International Nuclear Information System (INIS)

    Suarez Canner, E.

    1996-01-01

    The spectroscopy amplifier model AE-020 is designed to adjust suitable the pulses coming from nuclear radiation detectors. Due to is capacity and specifications, the amplifier can be used together with high and medium resolution spectroscopy system

  13. Portable musical instrument amplifier

    Science.gov (United States)

    Christian, David E.

    1990-07-24

    The present invention relates to a musical instrument amplifier which is particularly useful for electric guitars. The amplifier has a rigid body for housing both the electronic system for amplifying and processing signals from the guitar and the system's power supply. An input plug connected to and projecting from the body is electrically coupled to the signal amplifying and processing system. When the plug is inserted into an output jack for an electric guitar, the body is rigidly carried by the guitar, and the guitar is operatively connected to the electrical amplifying and signal processing system without use of a loose interconnection cable. The amplifier is provided with an output jack, into which headphones are plugged to receive amplified signals from the guitar. By eliminating the conventional interconnection cable, the amplifier of the present invention can be used by musicians with increased flexibility and greater freedom of movement.

  14. Amplification factor variable amplifier

    NARCIS (Netherlands)

    Akitsugu, Oshita; Nauta, Bram

    2007-01-01

    PROBLEM TO BE SOLVED: To provide an amplification factor variable amplifier capable of achieving temperature compensation of an amplification factor over a wide variable amplification factor range. ; SOLUTION: A Gilbert type amplification factor variable amplifier 11 amplifies an input signal and

  15. Amplification factor variable amplifier

    NARCIS (Netherlands)

    Akitsugu, Oshita; Nauta, Bram

    2010-01-01

    PROBLEM TO BE SOLVED: To provide an amplification factor variable amplifier capable of achieving temperature compensation of an amplification factor over a wide variable amplification factor range. ;SOLUTION: A Gilbert type amplification factor variable amplifier 11 amplifies an input signal and can

  16. Characterization of ultrafine aluminum nanoparticles

    International Nuclear Information System (INIS)

    Sandstrom, Mary M.; Jorgensen, Betty S.; Mang, Joseph T.; Smith, Bettina L.; Son, Steven F.

    2004-01-01

    Aluminum nanopowders with particle sizes ranging from ∼25 nm to 80 nm were characterized by a variety of methods. We present and compare the results from common powder characterization techniques including transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), BET gas adsorption surface area analysis, thermogravimetric analysis (TGA), photon correlation spectroscopy (PCS), and low angle laser light scattering (LALLS). Aluminum nanoparticles consist of an aluminum core with an aluminum oxide coating. HRTEM measurements of both the particle diameter and oxide layer thickness tend to be larger than those obtained from BET and TGA. LALLS measurements show a large degree of particle agglomeration in solution; therefore, primary particle sizes could not be determined. Furthermore, results from small-angle scattering techniques (SAS), including small-angle neutron (SANS) and x-ray (SAXS) scattering are presented and show excellent agreement with the BET, TGA, and HRTEM. The suite of analytical techniques presented in this paper can be used as a powerful tool in the characterization of many types of nanosized powders.

  17. CERN: Energy amplifier

    International Nuclear Information System (INIS)

    Anon.

    1995-01-01

    Even under the heavy burden of responsibility as CERN's Director General from 1989-3 the fertile mind of Carlo Rubbia the scientist was never still. A long-time Rubbia 'hobby' has been the search for new sources of nuclear energy, exploiting knowledge and skills from high energy physics. An initial objective was to adopt heavy ion techniques to induce controlled thermonuclear fusion, but in 1994 this quest changed direction. Putting the problems of thermonuclear fusion aside, Rubbia began to explore an alternative route to energy production through controlled nuclear fission. The idea is to use a particle accelerator producing neutrons by spallation (interaction of particles with a target) to feed a fuel/moderator assembly where the neutrons multiply by fission chain reactions. If the energy liberated becomes substantially greater than that needed to drive the accelerator, the process has a net gain and becomes selfsupporting. Hence the name ''Energy Amplifier'' (EA). Similar systems for energy production or for nuclear waste incineration have been proposed at Los Alamos and in Japan and Russia, but appear to require the prior development of innovative linear accelerators. For Rubbia's Amplifier, the requisite accelerator is a reasonable extrapolation of an existing cyclotron such that at the Swiss Paul Scherrer Institute. Moreover, the EA would require fuel rods very similar to those of conventional reactors, rather than demand-ing new technology using liquid fuel loops (molten salts) with on-line separation of radioactive products. Unlike a reactor, the EA's fission reaction is not self-sustaining: it is sub-critical and needs a continuous supply of neutrons from the accelerator. This makes Chernobyl-type meltdowns unlikely: if the accelerator stops, the reaction stops too. Another major advantage is that the old dream of using thorium as a fuel is now made possible. Thorium is not itself fissile, but under neutron

  18. Small-signal analysis and particle-in-cell simulations of planar dielectric Cherenkov masers for use as high-frequency, moderate-power broadband amplifiers

    International Nuclear Information System (INIS)

    Carlsten, Bruce E.

    2002-01-01

    A small-signal gain analysis of the planar dielectric Cherenkov maser is presented. The analysis results in a Pierce gain solution, with three traveling-wave modes. The analysis shows that the dielectric Cherenkov maser has a remarkable broadband tuning ability near cutoff, while maintaining reasonable gain rates. Numerical simulations verifying the small-signal gain results are presented, using a particle-in-cell code adapted specifically for planar traveling-wave tubes. An instantaneous bandwidth is numerically shown to be very large, and saturated efficiency for a nominal high-power design is shown to be in the range of standard untapered traveling-wave tubes

  19. Mechanochemical synthesis of ultrafine Ce2S3 powder

    International Nuclear Information System (INIS)

    Tsuzuki, T.; McCormick, P.G.

    1998-01-01

    Full text: Rare earth sulphides have been receiving an increasing attraction for various applications including infrared window materials and magneto-optical devices. In particular, Ce 2 S 3 has been under intensive study for use as a red pigment to replace toxic cadmium sulfoselenide. The conventional method for synthesising Ce 2 S 3 is the sulphidization of the element or sesquioxide with hydrogen sulphide gas. However, the method usually requires a high-temperature process (>1000 deg C), and hence coarse particles larger than the optimal size of ∼ 2 S 3 powder by mechanochemical processing using X-ray diffraction spectroscopy, BET surface area analysis and transmission electron microscopy. Mechanical milling of the mixture of a cerium salt and an alkali/alkali-earth sulphide powders led to a solid state displacement reaction in a steady-state manner, forming Ce 2 S 3 nanoparticles in a salt by-product matrix. After a simple washing process to remove the salt by-product, ultrafine Ce 2 S 3 particles with sizes of 20 - 200 nm having an orthorhombic structure were obtained. Using a diluent and mechanically alloyed CaS nanoparticles in the starting powder, particles of only a cubic γ-Ce 2 S 3 phase with sizes of 10 - 80 nm were formed

  20. A practice of ultra-fine tailings disposal as filling material in a gold mine.

    Science.gov (United States)

    Deng, D Q; Liu, L; Yao, Z L; Song, K I-I L; Lao, D Z

    2017-07-01

    A practice of cemented backfill technology with ultra-fine tailings in a gold mine was comprehensively presented, and a series of tests were conducted in accordance with the peculiar properties of ultra-fine tailings and the mining technology conditions. The test results show that, the tailings from Shuiyindong Gold Mine have a great grinding fineness, with the average particle diameter 22.03 μm, in which the ultra-fine particles with the diameter below 20 μm occupying 66.13%. The analysis results of chemical components of tailings indicate that the content of SiO 2 is relatively low, i.e., 33.08%, but the total content of CaO, MgO and Al 2 O 3 is relatively high i.e., 36.5%. After the settlement of 4-6 h, the tailing slurry with the initial concentration of 40% has the maximum settling concentration of 54.692%, and the corresponding maximum settling unit weight is 1.497 g/cm 3 . During the field application, the ultra-fine tailings and PC32.5 cement were mixed with the cement-tailings ratios of 1:3-1:8, and the slurry concentration of 50 wt% was prepared. Using the slurry pump, the prepared cemented backfill slurries flowed into the goaf, and then the strength of the cemented backfill body met the mining technique requirements in Shuiyindong Gold Mine, where the ore body has a smooth occurrence, with the average thickness of approximately 2 m and the inclination angle ranging from 5 to 10°. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Determination of permeability of ultra-fine cupric oxide aerosol through military filters and protective filters

    Science.gov (United States)

    Kellnerová, E.; Večeřa, Z.; Kellner, J.; Zeman, T.; Navrátil, J.

    2018-03-01

    The paper evaluates the filtration and sorption efficiency of selected types of military combined filters and protective filters. The testing was carried out with the use of ultra-fine aerosol containing cupric oxide nanoparticles ranging in size from 7.6 nm to 299.6 nm. The measurements of nanoparticles were carried out using a scanning mobility particle sizer before and after the passage through the filter and a developed sampling device at the level of particle number concentration approximately 750000 particles·cm-3. The basic parameters of permeability of ultra-fine aerosol passing through the tested material were evaluated, in particular particle size, efficiency of nanoparticle capture by filter, permeability coefficient and overall filtration efficiency. Results indicate that the military filter and particle filters exhibited the highest aerosol permeability especially in the nanoparticle size range between 100–200 nm, while the MOF filters had the highest permeability in the range of 200 to 300 nm. The Filter Nuclear and the Health and Safety filter had 100% nanoparticle capture efficiency and were therefore the most effective. The obtained measurement results have shown that the filtration efficiency over the entire measured range of nanoparticles was sufficient; however, it was different for particular particle sizes.

  2. Oscillators and operational amplifiers

    OpenAIRE

    Lindberg, Erik

    2005-01-01

    A generalized approach to the design of oscillators using operational amplifiers as active elements is presented. A piecewise-linear model of the amplifier is used so that it make sense to investigate the eigenvalues of the Jacobian of the differential equations. The characteristic equation of the general circuit is derived. The dynamic nonlinear transfer characteristic of the amplifier is investigated. Examples of negative resistance oscillators are discussed.

  3. Polyelectrolyte mediated nano hybrid particle as a nano-sensor with outstandingly amplified specificity and sensitivity for enzyme free estimation of cholesterol.

    Science.gov (United States)

    Chebl, Mazhar; Moussa, Zeinab; Peurla, Markus; Patra, Digambara

    2017-07-01

    As a proof of concept, here it is established that curcumin integrated chitosan oligosaccharide lactate (COL) self-assembles on silica nanoparticle surface to form nano hybrid particles (NHPs). These NHPs have size in the ranges of 25-35nm with silica nanoparticle as its core and curcumin-COL as outer layer having thickness of 4-8nm. The fluorescence intensity of these NHPs are found to be quenched and emission maximum is ~50nm red shifted compared to free curcumin implying inner filter effect and/or homo-FRET between curcumin molecules present on the surface of individual nano hybrid particle. Although fluorescence of free curcumin is remarkably quenched by Hg 2+ /Cu 2+ ions due to chelation through keto-enol form, the fluorescence of NHPs is unaffected by Hg 2+ /Cu 2+ ion that boosts analytical selectivity. The fluorescence intensity is outstandingly enhanced in the presence of cholesterol but is not influenced by ascorbic acid, uric acid, glucose, albumin, lipid and other potential interfering substances that either obstruct during enzymatic reaction or affect fluorescence of free curcumin. Thus, NHPs outstandingly improve analytical specificity, selectivity and sensitivity during cholesterol estimation compared to free curcumin. The interaction between cholesterol and NHPs is found to be a combination of ground state electrostatic interaction through the free hydroxyl group of cholesterol along with hydrophobic interaction between NHPs and cholesterol and excited state interaction. The proposed cholesterol biosensor illustrates a wider linear dynamic range, 0.002-10mmolL -1 , (upper limit is due to lack of solubility of cholesterol) needed for biomedical application and better than reported values during enzymatic reaction. In addition, the NHPs are found to be photo-stable potentially making it suitable for simple, quick and cost-effective cholesterol estimation and opening an alternative approach other than enzymatic reaction using nano hybrid structure to

  4. Physico-chemical properties and biological effects of diesel and biomass particles

    KAUST Repository

    Longhin, Eleonora; Gualtieri, Maurizio; Capasso, Laura; Bengalli, Rossella; Mollerup, Steen; Holme, Jø rn A.; Ø vrevik, Johan; Casadei, Simone; Di Benedetto, Cristiano; Parenti, Paolo; Camatini, Marina

    2016-01-01

    © 2016 Elsevier Ltd. Diesel combustion and solid biomass burning are the major sources of ultrafine particles (UFP) in urbanized areas. Cardiovascular and pulmonary diseases, including lung cancer, are possible outcomes of combustion particles

  5. LIGHT MICROSCOPY DETECTION OF NANOSCALE PARTICLE INTERNALIZATION BY HUMAN LUNG CELLS

    Science.gov (United States)

    RATIONALE. Ultrafine particulate matter (PM) is reported to be more strongly correlated with adverse health effects relative to larger particle size fractions. These epidemiological findings are supported by toxicological studies suggesting that particle size is inversely associa...

  6. Studies on composite solid propellant with tri-modal ammonium perchlorate containing an ultrafine fraction

    Directory of Open Access Journals (Sweden)

    K.V. Suresh Babu

    2017-08-01

    Full Text Available Composite solid propellant is prepared using tri-modal Ammonium perchlorate (AP containing coarse, fine and ultrafine fractions of AP with average particle size (APS 340, 40 and 5 μm respectively, in various compositions and their rheological, mechanical and burn rate characteristics are evaluated. The optimum combination of AP coarse to fine to ultrafine weight fraction was obtained by testing of series of propellant samples by varying the AP fractions at fixed solid loading. The concentration of aluminium was maintained constant throughout the experiments for ballistics requirement. The propellant formulation prepared using AP with coarse to fine to ultrafine ratio of 67:24:9 has lowest viscosity for the propellant paste and highest tensile strength due to dense packing as supported by the literature. A minimum modulus value was also observed at 9 wt. % of ultrafine AP concentration indicates the maximum solids packing density at this ratio of AP fractions. The burn rate is evaluated at different pressures to obtain pressure exponent. Incorporation of ultrafine fraction of AP in propellant increased burn rate without adversely affecting the pressure exponent. Higher solid loading propellants are prepared by increased AP concentration from 67 to 71 wt. % using AP with coarse to fine to ultrafine ratio of 67:24:9. Higher solid content up to 89 wt. % was achieved and hence increased solid motor performance. The unloading viscosity showed a trend with increased AP content and the propellant couldn't able to cast beyond 71 wt. % of AP. Mechanical properties were also studied and from the experiments noticed that % elongation decreased with increased AP content from 67 to 71 wt.%, whereas tensile strength and modulus increased. Burn rate increased with increased AP content and observed that pressure exponent also increased and it is high for the propellant containing with 71 wt.% of AP due to increased oxidiser to fuel ratio. Catalysed

  7. Source apportionment of fine (PM1.8) and ultrafine (PM0.1) airborne particulate matter during a severe winter pollution episode.

    Science.gov (United States)

    Kleeman, Michael J; Riddle, Sarah G; Robert, Michael A; Jakober, Chris A; Fine, Phillip M; Hays, Michael D; Schauer, James J; Hannigan, Michael P

    2009-01-15

    Size-resolved samples of airborne particulate matter (PM) collected during a severe winter pollution episode at three sites in the San Joaquin Valley of California were extracted with organic solvents and analyzed for detailed organic compounds using GC-MS. Six particle size fractions were characterized with diameter (Dp) < 1.8 microm; the smallest size fraction was 0.056 < Dp < 0.1 microm which accounts for the majority of the mass in the ultrafine (PM0.1) size range. Source profiles for ultrafine particles developed during previous studies were applied to the measurements at each sampling site to calculate source contributions to organic carbon (OC) and elemental carbon (EC) concentrations. Ultrafine EC concentrations ranged from 0.03 microg m(-3) during the daytime to 0.18 microg m(-3) during the nighttime. Gasoline fuel, diesel fuel, and lubricating oil combustion products accounted for the majority of the ultrafine EC concentrations, with relatively minor contributions from biomass combustion and meat cooking. Ultrafine OC concentrations ranged from 0.2 microg m(-3) during the daytime to 0.8 microg m(-3) during the nighttime. Wood combustion was found to be the largest source of ultrafine OC. Meat cooking was also identified as a significant potential source of PM0.1 mass but further study is required to verify the contributions from this source. Gasoline fuel, diesel fuel, and lubricating oil combustion products made minor contributions to PM0.1 OC mass. Total ultrafine particulate matter concentrations were dominated by contributions from wood combustion and meat cooking during the current study. Future inhalation exposure studies may wish to target these sources as potential causes of adverse health effects.

  8. Preparation of ultrafine poly(sodium 4-styrenesulfonate) fibres via ...

    Indian Academy of Sciences (India)

    The ultrafine poly (sodium 4-styrenesulfonate) (NaPSS) fibres have been prepared for the first time by electrospinning. The spinning solutions (NaPSS aqueous solutions) in varied concentrations were studied for electrospinning into ultrafine fibres. The results indicated that the smooth fibre could be formed when the ...

  9. Direct synthesis and structure characterization of ultrafine CeO2 nanoparticles

    International Nuclear Information System (INIS)

    Hu Chenguo; Zhang Zuwei; Liu Hong; Gao Puxian; Wang Zhonglin

    2006-01-01

    A new method to directly synthesize single-crystalline CeO 2 nanoparticles has been developed. The advantages of the method are rapid synthesis, at normal atmosphere, 100% productive ratio and low cost, with a great potential for scale-up. X-ray diffraction (XRD) spectra showed unusual peak width versus particle size, compared with Scherrer equation predictions. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), electron diffraction and ultraviolet (UV) absorption were used to examine the particle size and microstructure to find out the cause. As a result, ultrafine particles with a size less than 6 nm were found to be self-assembled into a 'coherent interface', so that a large group of particles behave like a large single particle in XRD

  10. FLUIDIC AC AMPLIFIERS.

    Science.gov (United States)

    Several fluidic tuned AC Amplifiers were designed and tested. Interstage tuning and feedback designs are considered. Good results were obtained...corresponding Q’s as high as 12. Element designs and test results of one, two, and three stage amplifiers are presented. AC Modulated Carrier Systems

  11. Antares laser power amplifier

    International Nuclear Information System (INIS)

    Stine, R.D.; Ross, G.F.; Silvernail, C.

    1979-01-01

    The overall design of the Antares laser power amplifier is discussed. The power amplifier is the last stage of amplification in the 100-kJ Antares laser. In the power amplifier a single, cylindrical, grid-controlle, cold-cathode electron gun is surrounded by 12 large-aperture CO 2 electron-beam sustained laser discharge sectors. Each power amplifier will deliver 18 kJ and the six modules used in Antares will produce the required 100 kJ for delivery to the target. A large-scale interaction between optical, mechanical, and electrical disciplines is required to meet the design objectives. Significant component advances required by the power amplifier design are discussed

  12. Measurements of the effect of humidity on radio-aerosol penetration through ultrafine capillaries

    International Nuclear Information System (INIS)

    Cullen, C.

    1996-08-01

    The purpose of this research was to examine the effects of humidity on radio-aerosol penetration through ultrafine capillaries. A number of tests were conducted at relative humidities of 20%, 50%, and 80%, with sampling times of 20, 40, and 60 min. The radio-aerosol consisted of polystyrene particles with a diameter of 0.1 microm. The ultrafine capillaries had a diameter of 250 microm. The data from these tests varied significantly. These results made the identification of radio-aerosol penetration trends inconclusive. The standard deviation for all penetration data ranged from 3% to 30%. The results of this study suggest that a better control of the experimental parameters was needed to obtain more accurate data from experiments associated with radio-aerosol penetration in the presence of moisture. The experimental parameters that may have contributed to the wide variance of data, include aerosol flow, radio-aerosol generation, capillary characteristics, humidity control, and radiation measurements. It was the uncertainty of these parameters that contributed to the poor data which made conclusive deductions about radio-aerosol penetration dependence on humidity difficult. The application of this study is to ultrafine leaks resulting from stress fractures in high-level nuclear waste transportation casks under accident scenarios

  13. [The species traceability of the ultrafine powder and the cell wall-broken powder of herbal medicine based on DNA barcoding].

    Science.gov (United States)

    Xiang, Li; Tang, Huan; Cheng, Jin-le; Chen, Yi-long; Deng, Wen; Zheng, Xia-sheng; Lai, Zhi-tian; Chen, Shi-lin

    2015-12-01

    Ultrafine powder and cell wall-broken powder of herbal medicine lack of the morphological characters and microscopic identification features. This makes it hard to identify herb's authenticity with traditional methods. We tested ITS2 sequence as DNA barcode in identification of herbal medicine in ultrafine powder and cell wall-broken powder in this study. We extracted genomic DNAs of 93 samples of 31 representative herbal medicines (28 species), which include whole plant, roots and bulbs, stems, leaves, flowers, fruits and seeds. The ITS2 sequences were amplified and sequenced bidirectionally. The ITS2 sequences were identified using Basic Local Alignment Search Tool (BLAST) method in the GenBank database and DNA barcoding system to identify the herbal medicine. The genetic distance was analyzed using the Kimura 2-parameter (K2P) model and the Neighbor-joining (NJ) phylogenetic tree was constructed using MEGA 6.0. The results showed that DNA can be extracted successfully from 93 samples and high quality ITS2 sequences can be amplified. All 31 herbal medicines can get correct identification via BLAST method. The ITS2 sequences of raw material medicines, ultrafine powder and cell wall-broken powder have same sequence in 26 herbal medicines, while the ITS2 sequences in other 5 herbal medicines exhibited variation. The maximum intraspecific genetic-distances of each species were all less than the minimum interspecific genetic distances. ITS2 sequences of each species are all converged to their standard DNA barcodes using NJ method. Therefore, using ITS2 barcode can accurately and effectively distinguish ultrafine powder and cell wall-broken powder of herbal medicine. It provides a new molecular method to identify ultrafine powder and cell wall-broken powder of herbal medicine in the quality control and market supervision.

  14. Auto-Zero Differential Amplifier

    Science.gov (United States)

    Quilligan, Gerard T. (Inventor); Aslam, Shahid (Inventor)

    2017-01-01

    An autozero amplifier may include a window comparator network to monitor an output offset of a differential amplifier. The autozero amplifier may also include an integrator to receive a signal from a latched window comparator network, and send an adjustment signal back to the differential amplifier to reduce an offset of the differential amplifier.

  15. Development and applications of ultrafine aluminium powders

    International Nuclear Information System (INIS)

    Kearns, Martin

    2004-01-01

    Over the last 20 years or so, a variety of new technologies has been developed to produce sub-micron powders. Among the products attracting interest is nanoaluminium which is being evaluated in specialist propulsion and exothermic end-uses. This paper examines the advances made in 'nanopowder' production in the context of the existing aluminium powder industry where finest commercial grades have a median size of ∼6 μm (one or two orders of magnitude coarser than nanopowders) and which today supplies the markets being targeted by nanopowders with coarser, but effective products. Are there genuine market opportunities for nanoaluminium and if so, how will they be produced? One the one hand there are the novel nanopowder production methods which are high yielding but generally slow and costly, while on the other, there is the very fine fraction from conventional atomising routes which generate a very low yield of sub-micron powder but which nevertheless can translate into a meaningful rate as part of the bulk production. Can conventional routes ever hope to make sufficient volumes of nanopowders cost effectively and which will be the favoured routes in future? Moreover, what of the 'ultrafine' size range (∼0.5-5 μm) which is of more immediate potential interest to today's powder users. This paper seeks to identify the near term opportunities for application of low volume/high value ultrafine and nano powders

  16. Noise in Optical Amplifiers

    DEFF Research Database (Denmark)

    Jeppesen, Palle

    1997-01-01

    Noise in optical amplifiers is discussed on the basis of photons and electromagntic fields. Formulas for quantum noise from spontaneous emission, signal-spontaneous beat noise and spontaneous-spontaneous beat noise are derived.......Noise in optical amplifiers is discussed on the basis of photons and electromagntic fields. Formulas for quantum noise from spontaneous emission, signal-spontaneous beat noise and spontaneous-spontaneous beat noise are derived....

  17. Pulmonary Delivery of an Ultra-Fine Oxytocin Dry Powder Formulation: Potential for Treatment of Postpartum Haemorrhage in Developing Countries

    OpenAIRE

    Prankerd, Richard J.; Nguyen, Tri-Hung; Ibrahim, Jibriil P.; Bischof, Robert J.; Nassta, Gemma C.; Olerile, Livesey D.; Russell, Adrian S.; Meiser, Felix; Parkington, Helena C.; Coleman, Harold A.; Morton, David A. V.; McIntosh, Michelle P.

    2013-01-01

    Oxytocin is recommended by the World Health Organisation as the most effective uterotonic for the prevention and treatment of postpartum haemorrhage. The requirement for parenteral administration by trained healthcare providers and the need for the drug solution to be maintained under cold-chain storage limit the use of oxytocin in the developing world. In this study, a spray-dried ultrafine formulation of oxytocin was developed with an optimal particle size diameter (1-5 µm) to facilitate ae...

  18. Spatial and temporal variation of sources contributing to quasi-ultrafine particulate matter PM0.36 in Augsburg, Germany.

    Science.gov (United States)

    Li, Fengxia; Schnelle-Kreis, Jürgen; Cyrys, Josef; Wolf, Kathrin; Karg, Erwin; Gu, Jianwei; Orasche, Jürgen; Abbaszade, Gülcin; Peters, Annette; Zimmermann, Ralf

    2018-08-01

    to study the sources contributing to quasi-ultrafine particle (UFP) organic carbon and the spatial temporal variability of the sources. 24h quasi-UFP (particulate matter quasi-UFP vary among sites and source types and show source-specific characteristics. Therefore, caution should be taken when using one monitor site measurement to assess human exposure in health effect studies of quasi-UFP. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. Personal exposure to ultrafine particles and oxidative DNA damage

    DEFF Research Database (Denmark)

    Vinzents, Peter S; Møller, Peter; Sørensen, Mette

    2005-01-01

    10), nitrous oxide, nitrogen dioxide, carbon monoxide, and/or number concentration of UFPs at urban background or busy street monitoring stations was not a significant predictor of DNA damage, although personal UFP exposure was correlated with urban background concentrations of CO and NO2...... the morning after exposure measurement. Cumulated outdoor and cumulated indoor exposures to UFPs each were independent significant predictors of the level of purine oxidation in DNA but not of strand breaks. Ambient air concentrations of particulate matter with an aerodynamic diameter of ..., particularly during bicycling in traffic. The results indicate that biologic effects of UFPs occur at modest exposure, such as that occurring in traffic, which supports the relationship of UFPs and the adverse health effects of air pollution....

  20. Phase noise in RF and microwave amplifiers.

    Science.gov (United States)

    Boudot, Rodolphe; Rubiola, Enrico

    2012-12-01

    Understanding amplifier phase noise is a critical issue in many fields of engineering and physics, such as oscillators, frequency synthesis, telecommunication, radar, and spectroscopy; in the emerging domain of microwave photonics; and in exotic fields, such as radio astronomy, particle accelerators, etc. Focusing on the two main types of base noise in amplifiers, white and flicker, the power spectral density of the random phase φ(t) is Sφ(f) = b(0) + b(-1)/f. White phase noise results from adding white noise to the RF spectrum in the carrier region. For a given RF noise level, b(0) is proportional to the reciprocal of the carrier power P(0). By contrast, flicker results from a near-dc 1/f noise-present in all electronic devices-which modulates the carrier through some parametric effect in the semiconductor. Thus, b(-1) is a parameter of the amplifier, constant in a wide range of P(0). The consequences are the following: Connecting m equal amplifiers in parallel, b(-1) is 1/m times that of one device. Cascading m equal amplifiers, b(-1) is m times that of one amplifier. Recirculating the signal in an amplifier so that the gain increases by a power of m (a factor of m in decibels) as a result of positive feedback (regeneration), we find that b(-1) is m(2) times that of the amplifier alone. The feedforward amplifier exhibits extremely low b(-1) because the carrier is ideally nulled at the input of its internal error amplifier. Starting with an extensive review of the literature, this article introduces a system-oriented model which describes the phase flickering. Several amplifier architectures (cascaded, parallel, etc.) are analyzed systematically, deriving the phase noise from the general model. There follow numerous measurements of amplifiers using different technologies, including some old samples, and in a wide frequency range (HF to microwaves), which validate the theory. In turn, theory and results provide design guidelines and give suggestions for CAD and

  1. Nuclear microprobe investigation of the penetration of ultrafine zinc oxide into human skin affected by atopic dermatitis

    Science.gov (United States)

    Szikszai, Z.; Kertész, Zs.; Bodnár, E.; Borbíró, I.; Angyal, A.; Csedreki, L.; Furu, E.; Szoboszlai, Z.; Kiss, Á. Z.; Hunyadi, J.

    2011-10-01

    Skin penetration is one of the potential routes for nanoparticles to gain access into the human body. Ultrafine metal oxides, such as titanium dioxide and zinc oxide are widely used in cosmetic and health products like sunscreens. These oxides are potent UV filters and the particle size smaller than 200 nm makes the product more transparent compared to formulations containing coarser particles. The present study continues the work carried out in the frame of the NANODERM: “Quality of skin as a barrier to ultrafine particles” European project and complements our previous investigations on human skin with compromised barrier function. Atopic dermatitis (a type of eczema) is an inflammatory, chronically relapsing, non-contagious skin disease. It is very common in children but may occur at any age. The exact cause of atopic dermatitis is unknown, but is likely due to a combination of impaired barrier function together with a malfunction in the body's immune system. In this study, skin samples were obtained from two patients suffering from atopic dermatitis. Our results indicate that the ultrafine zinc oxide particles, in a hydrophobic basis gel with an application time of 2 days or 2 weeks, have penetrated deeply into the stratum corneum in these patients. On the other hand, penetration into the stratum spinosum was not observed even in the case of the longer application time.

  2. Granularity and Laxative Effect of Ultrafine Powder of Dendrobium officinale.

    Science.gov (United States)

    Luo, DanDan; Qu, Chao; Zhang, ZhenBiao; Xie, JianHui; Xu, LieQiang; Yang, HongMei; Li, CaiLan; Lin, GuoSheng; Wang, HongFeng; Su, ZiRen

    2017-02-01

    Constipation is a common disorder that is a significant source of morbidity among people around the world ranging from 2% to 28%. Dendrobium officinale Kimura et Migo is a traditional herbal medicine and health food used for tonicity of the stomach and promotion of body fluid production in China. This study aimed to prepare the ultrafine powder of Dendrobium officinale (UDO) and investigate its laxative effect and potential mechanism in mice with diphenoxylate-induced constipation. Results indicated that the mean diameter (d 50 ) of UDO obtained by ball milling was 6.56 μm. UDO (62.5, 125, and 250 mg/kg, p.o.) could significantly enhance the gastrointestinal transit ratio and promote fecal output. Moreover, UDO treatment resulted in significant increases in the serum levels of acetylcholinesterase (AChE), gastrin (Gas), motilin (MTL), and substance P (SP), and obviously decreased serum contents of somatostatin (SS). Taken together, UDO, which can be easily obtained through milling to a satisfactory particle size, exhibited obvious laxative effect in diphenoxylate-induced constipated mice, and the mechanism might be associated with elevated levels of AChE, Gas, MTL, SP, and reduced production of SS. UDO has the potential for further development into an alternative effective diet therapy for constipation.

  3. Ultrafine coal classification using 150 mm gMax cyclone circuits

    Energy Technology Data Exchange (ETDEWEB)

    Honaker, R.Q.; Boaten, F.; Luttrell, G.H. [University of Kentucky, Lexington, KY (United States). Dept. of Mineral Engineering

    2007-11-15

    A two-stage classification circuit using 150 mm diameter gMax cyclones was installed and evaluated in a coal preparation plant in an effort to achieve a clean coal product without the use of froth flotation. Particle size separations of around 37 {mu}m were achieved while limiting ultrafine bypass to less than 10% in the circuit underflow stream. As a result, approximately 81% of the ash-bearing material in the circuit feed was rejected to the circuit overflow stream. The feed ash content was reduced from around 50% to values in the range of 22-30% in the circuit underflow stream with a mass recovery of about 30%. Further reductions in the coarse product ash content were limited due to the particle density effect and the remaining presence of a significant quantity of high-ash slime material in the coarse product. The typical D{sub 50} for the coal particles was 40 {mu} m while the estimated value for mineral matter was 17 {mu} m. Based on the findings of the study, the use of classification to recover a low-ash, coarse fraction in the feed of a fine coal circuit is limited by the density effect regardless of the ability to eliminate ultrafine bypass.

  4. Ultrafine PEG-coated poly(lactic-co-glycolic acid) nanoparticles formulated by hydrophobic surfactant-assisted one-pot synthesis for biomedical applications.

    Science.gov (United States)

    Chu, Chih-Hang; Wang, Yu-Chao; Huang, Hsin-Ying; Wu, Li-Chen; Yang, Chung-Shi

    2011-05-06

    A novel method was developed for the one-pot synthesis of ultrafine poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs), using an emulsion solvent evaporation formulation method. Using either cetyltrimethylammonium bromide (CTAB) or poly(ethylene glycol)-distearyl phosphoethanolamine (PEGPE) as an oily emulsifier during the emulsion process, produced PLGA particle sizes of less than 50 nm, constituting a breakthrough in emulsion formulation methods. The yield of ultrafine PLGA NPs increased with PEGPE/PLGA ratio, reaching a plateau at around 85%, when the PEGPE/PLGA ratio reached 3:1. The PEGPE-PLGA NPs exhibited high drug loading content, reduced burst release, good serum stability, and enhanced cell uptake rate compared with traditional PLGA NPs. Sub-50 nm diameter PEG-coated ultrafine PLGA NPs show great potential for in vivo drug delivery systems.

  5. Semi-quantitative characterisation of ambient ultrafine aerosols resulting from emissions of coal fired power stations

    International Nuclear Information System (INIS)

    Hinkley, J.T.; Bridgman, H.A.; Buhre, B.J.P.; Gupta, R.P.; Nelson, P.F.; Wall, T.F.

    2008-01-01

    Emissions from coal fired power stations are known to be a significant anthropogenic source of fine atmospheric particles, both through direct primary emissions and secondary formation of sulfate and nitrate from emissions of gaseous precursors. However, there is relatively little information available in the literature regarding the contribution emissions make to the ambient aerosol, particularly in the ultrafine size range. In this study, the contribution of emissions to particles smaller than 0.3 μm in the ambient aerosol was examined at a sampling site 7 km from two large Australian coal fired power stations equipped with fabric filters. A novel approach was employed using conditional sampling based on sulfur dioxide (SO 2 ) as an indicator species, and a relatively new sampler, the TSI Nanometer Aerosol Sampler. Samples were collected on transmission electron microscope (TEM) grids and examined using a combination of TEM imaging and energy dispersive X-ray (EDX) analysis for qualitative chemical analysis. The ultrafine aerosol in low SO 2 conditions was dominated by diesel soot from vehicle emissions, while significant quantities of particles, which were unstable under the electron beam, were observed in the high SO 2 samples. The behaviour of these particles was consistent with literature accounts of sulfate and nitrate species, believed to have been derived from precursor emissions from the power stations. A significant carbon peak was noted in the residues from the evaporated particles, suggesting that some secondary organic aerosol formation may also have been catalysed by these acid seed particles. No primary particulate material was observed in the minus 0.3 μm fraction. The results of this study indicate the contribution of species more commonly associated with gas to particle conversion may be more significant than expected, even close to source

  6. Electrospun amplified fiber optics.

    Science.gov (United States)

    Morello, Giovanni; Camposeo, Andrea; Moffa, Maria; Pisignano, Dario

    2015-03-11

    All-optical signal processing is the focus of much research aiming to obtain effective alternatives to existing data transmission platforms. Amplification of light in fiber optics, such as in Erbium-doped fiber amplifiers, is especially important for efficient signal transmission. However, the complex fabrication methods involving high-temperature processes performed in a highly pure environment slow the fabrication process and make amplified components expensive with respect to an ideal, high-throughput, room temperature production. Here, we report on near-infrared polymer fiber amplifiers working over a band of ∼20 nm. The fibers are cheap, spun with a process entirely carried out at room temperature, and shown to have amplified spontaneous emission with good gain coefficients and low levels of optical losses (a few cm(-1)). The amplification process is favored by high fiber quality and low self-absorption. The found performance metrics appear to be suitable for short-distance operations, and the large variety of commercially available doping dyes might allow for effective multiwavelength operations by electrospun amplified fiber optics.

  7. Reverse Taylor Tests on Ultrafine Grained Copper

    International Nuclear Information System (INIS)

    Mishra, A.; Meyers, M. A.; Martin, M.; Thadhani, N. N.; Gregori, F.; Asaro, R. J.

    2006-01-01

    Reverse Taylor impact tests have been carried out on ultrafine grained copper processed by Equal Channel Angular Pressing (ECAP). Tests were conducted on an as-received OFHC Cu rod and specimens that had undergone sequential ECAP passes (2 and 8). The average grain size ranged from 30 μm for the initial sample to less than 0.5 μm for the 8-pass samples. The dynamic deformation states of the samples, captured by high speed digital photography were compared with computer simulations run in AUTODYN-2D using the Johnson-Cook constitutive equation with constants obtained from stress-strain data and by fitting to an experimentally measured free surface velocity trace. The constitutive response of copper of varying grain sizes was obtained through quasistatic and dynamic mechanical tests and incorporation into constitutive models

  8. Rapid preparation of ultrafine BaSO{sub 3} by SO{sub 2} storage material

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fei; Sha, Feng; Qiao, Xian Shu; Zhao, Tian Xiang; Guo, Bo; Zhang, Jian Bin [College of Chemical Engineering, Inner Mongolia University of Technology, Huhhot (Korea, Republic of)

    2017-01-15

    In this work, a green and efficient process was developed for the preparation of ultrafine BaSO{sub 3} with layered nanostructure surface via the reaction of BaCl{sub 2} with a SO{sub 2} storage material (SO{sub 2}SM) at room temperature. The absorption of SO{sub 2} with equimolar ethylenediamine (EDA) and ethylene glycol (EG) afforded SO{sub 2}SM, which not only offered alkyl sulfite but also released EDA and EG that served as efficient surfactants to promote the formation of BaSO{sub 3} with spherical morphology and porous structure in the process of synthesis of ultrafine BaSO{sub 3}. The factors affecting the morphology and size of BaSO{sub 3} particle were assessed by investigating the effects of SO{sub 2}SM concentration, BaCl{sub 2} concentration, stirring time and speed. It was found that a higher SO{sub 2}SM concentration led to a higher degree of supersaturation, and the particle size of BaSO{sub 3} could be reduced by increasing SO{sub 2}SM concentration. Moreover, under the identified optimal reaction conditions, ultrafine BaSO{sub 3} was obtained with an average diameter of 450 nm. In addition, a plausible formation process of BaSO{sub 3} was proposed to explain the observed reaction results. Overall, the developed process in this work provides an efficient method for the capture, utilization, and conversion of SO{sub 2} into a valuable chemical.

  9. Fast logarithmic amplifier

    International Nuclear Information System (INIS)

    Tai, I.; Hasegawa, K.

    1975-01-01

    This paper reports on the improvement of frequency characteristics of a logarithmic amplifier with a Paterson transdiode connection. The improvement of the response speed has been achieved by using a phase compensation technique. Small signal response analyses of the logging circuit revealed the effects of a series resistor Rsub(p) and a parallel capacitance Csub(p) on the response of the circuit. The improvement of the frequency characteristics are remarkable at higher current levels. These facts were proved by the practical logarithmic amplifier. (auth.)

  10. Electrochemically Formed Ultrafine Metal Oxide Nanocatalysts for High-Performance Lithium–Oxygen Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Bin; Yan, Pengfei; Xu, Wu; Zheng, Jianming; He, Yang; Luo, Langli; Bowden, Mark E.; Wang, Chong-Min; Zhang, Ji-Guang

    2016-08-10

    Lithium-oxygen (Li-O2) battery has an extremely high theoretical specific energy density as compared with conventional energy storage systems. However, practical application of Li-O2 battery system still faces significant challenges, especially its poor cyclability. In this work, we report a new approach to synthesis ultrafine metal oxide nanocatalysts through an electrochemical pre-lithiation process. This process reduces the size of NiCo2O4 (NCO) particles from 20~30 nm to a uniformly distributed domain of ~ 2 nm and largely improved their catalytic activity. Structurally, the pre-lithiated NCO NWs are featured by ultrafine NiO/CoO nanoparticles, which show high stability during prolonged cycles in terms of morphology and the particle size, therefore maintaining an excellent catalytic effect to oxygen reduction and evolution reactions. Li-O2 battery using this catalyst has demonstrated an initial capacity of 29,280 mAh g-1 and has retained a stable capacity of over 1,000 mAh g-1 after 100 cycles based on the weight of NCO active material. Direct in-situ TEM observation conclusively reveals the lithiation/delithiation process of as-prepared NCO NWs, clarifying the NCO/Li electrochemical reaction mechanism that can be extended to other transition-metal oxides and providing the in depth understandings on the catalysts and battery chemistries of other ternary transition-metal oxides.

  11. A parametric comparative study of electrocoagulation and coagulation using ultrafine quartz suspensions.

    Science.gov (United States)

    Kiliç, Mehtap Gülsün; Hoşten, Cetin; Demirci, Sahinde

    2009-11-15

    This paper attempts to compare electrocoagulation using aluminum anodes and stainless steel cathodes with conventional coagulation by aluminum sulfate dosing on aqueous suspensions of ultrafine quartz. Several key parameters affecting the efficiency of electrocoagulation and coagulation were investigated with laboratory scale experiments in search of optimal parameter values. Optimal values of the parameters were determined on the basis of the efficiency of turbidity removal from ultrafine quartz suspensions. The parameters investigated in the study were suspension pH, electrical potential, current density, electrocoagulation time, and aluminum dosage. A comparison between electrocoagulation and coagulation was made on the basis of total dissolved aluminum, revealing that electrocoagulation and coagulation were equally effective at the same aluminum dosage for the removal of quartz particles from suspensions. Coagulation, however, was more effective in a wider pH range (pH 6-9) than electrocoagulation which yielded optimum effectiveness in a relatively narrower pH range around 9, where, in both methods, these pH values corresponded to near-zero zeta potentials of quartz particles. Furthermore, experimental results confirmed that electrocoagulation could display some pH buffering capacity. The kinetics of electrocoagulation was very fast (<10 min) in approaching a residual turbidity, which could be modeled with a second-order rate equation.

  12. Two-step sintering of ultrafine-grained barium cerate proton conducting ceramics

    International Nuclear Information System (INIS)

    Wang, Siwei; Zhang, Lei; Zhang, Lingling; Brinkman, Kyle; Chen, Fanglin

    2013-01-01

    Ultra-fine grained dense BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3−δ (BZCYYb) ceramics have been successfully prepared via a two-step sintering method. Co-precipitation method has been adopted to prepare nano-sized BZCYYb precursors with an average particle size of 30 nm. By controlling the sintering profile, an average grain size of 184 nm was obtained for dense BZCYYb ceramics via the two-step sintering method, compared to 445 nm for the conventional sintered samples. The two-step sintered BZCYYb samples showed less impurity and an enhanced electrical conductivity compared with the conventional sintered ones. Further, the two-step sintering method was applied to fabricate anode supported solid oxide fuel cells (SOFCs) using BZCYYb as the electrolyte, resulting in dense ultrafine-grained electrolyte membranes and porous anode substrates with fine particles. Due to the reduced ohmic as well as polarization resistances, the maximum power output of the cells fabricated from the two-step sintering method reached 349 mW m −2 at 700 °C, significantly improved from 172 mW cm −2 for the conventional sintered cells, suggesting that two-step sintering method is very promising for optimizing the microstructure and thus enhancing the electrochemical performances for barium cerate based proton-conducting SOFCs.

  13. Amplifier Design for Proportional Ionization Chambers

    Energy Technology Data Exchange (ETDEWEB)

    Baker, W. H.

    1950-08-24

    This paper presents the requirements of a nuclear amplifier of short resolving time, designed to accept pulses of widely varying amplitudes. Data are given which show that a proportional ionization chamber loaded with a 1,000-ohm resistor develops pulses of 0.5 microsecond duration and several volts amplitude. Results indicate that seven basic requirements are imposed on the amplifier when counting soft beta and gamma radiation in the presence of alpha particles, without absorbers. It should, (1) have a fast recovery time, (2) have a relatively good low frequency response, (3) accept pulses of widely varying heights without developing spurious pulsed, (4) have a limiting output stage, (5) preserve the inherently short rise time of the chamber, (6) minimize pulse integration, and (7) have sufficient gain to detect the weak pulses well below the chamber voltage at which continuous discharge takes place. The results obtained with an amplifier which meets these requirements is described. A formula is derived which indicates that redesign of the proportional ionization chamber might eliminate the need for an amplifier. This may be possible if the radioactive particles are collimated parallel to the collecting electrode.

  14. Formation of ultra-fine grained SUS316L steels by ball-milling and their mechanical properties after neutron irradiation

    International Nuclear Information System (INIS)

    Zheng, Y.J.; Yamasaki, T.; Fukami, T.; Terasawa, M.; Mitamura, T.

    2003-01-01

    In order to overcome the irradiation embrittlement in austenitic stainless steels, ultra-fine grained SUS316L steels with very fine TiC particles have been developed. The SUS316L-TiC nanocomposite powders having 1.0 to 2.0 mass% TiC were prepared by ball-milling SUS316L-TiC powder mixtures for 125 h in an argon gas atmosphere. The milled powders were consolidated by hot isostatic pressing (HIP) under a pressure of 200 MPa at temperatures between 700 and 1000 C, and the bulk materials with grain sizes between 100 and 400 nm have been produced. The possibility of using fine-grained TiC particles to pin grain boundaries and thereby maintain the ultra-fine grained structures has been discussed. In order to clarify the effects of the neutron irradiation on mechanical properties of the ultra-fine grained SUS316L steels, Vickers microhardness measurements were performed before and after the irradiation of 1.14 x 10 23 n/m 2 and 1.14 x 10 24 n/m 2 . The hardness increased with increasing the dose of the irradiation. However, these increasing rates of the ultra-fine grained steels were much smaller than those of the coarse-grained SUS316L steels having grain sizes between 13 and 50 μm. (orig.)

  15. Ice crystallization in ultrafine water-salt aerosols: nucleation, ice-solution equilibrium, and internal structure.

    Science.gov (United States)

    Hudait, Arpa; Molinero, Valeria

    2014-06-04

    Atmospheric aerosols have a strong influence on Earth's climate. Elucidating the physical state and internal structure of atmospheric aqueous aerosols is essential to predict their gas and water uptake, and the locus and rate of atmospherically important heterogeneous reactions. Ultrafine aerosols with sizes between 3 and 15 nm have been detected in large numbers in the troposphere and tropopause. Nanoscopic aerosols arising from bubble bursting of natural and artificial seawater have been identified in laboratory and field experiments. The internal structure and phase state of these aerosols, however, cannot yet be determined in experiments. Here we use molecular simulations to investigate the phase behavior and internal structure of liquid, vitrified, and crystallized water-salt ultrafine aerosols with radii from 2.5 to 9.5 nm and with up to 10% moles of ions. We find that both ice crystallization and vitrification of the nanodroplets lead to demixing of pure water from the solutions. Vitrification of aqueous nanodroplets yields nanodomains of pure low-density amorphous ice in coexistence with vitrified solute rich aqueous glass. The melting temperature of ice in the aerosols decreases monotonically with an increase of solute fraction and decrease of radius. The simulations reveal that nucleation of ice occurs homogeneously at the subsurface of the water-salt nanoparticles. Subsequent ice growth yields phase-segregated, internally mixed, aerosols with two phases in equilibrium: a concentrated water-salt amorphous mixture and a spherical cap-like ice nanophase. The surface of the crystallized aerosols is heterogeneous, with ice and solution exposed to the vapor. Free energy calculations indicate that as the concentration of salt in the particles, the advance of the crystallization, or the size of the particles increase, the stability of the spherical cap structure increases with respect to the alternative structure in which a core of ice is fully surrounded by

  16. Soot, organics, and ultrafine ash from air- and oxy-fired coal combustion

    KAUST Repository

    Andersen, Myrrha E.

    2016-10-19

    Pulverized bituminous coal was burned in a 10. W externally heated entrained flow furnace under air-combustion and three oxy-combustion inlet oxygen conditions (28, 32, and 36%). Experiments were designed to produce flames with practically relevant stoichiometric ratios (SR. =1.2-1.4) and constant residence times (2.3. s). Size-classified fly ash samples were collected, and measurements focused on the soot, elemental carbon (EC), and organic carbon (OC) composition of the total and ultrafine (<0.6. μm) fly ash. Results indicate that although the total fly ash carbon, as measured by loss on ignition, was always acceptably low (<2%) with all three oxy-combustion conditions lower than air-combustion, the ultrafine fly ash for both air-fired and oxy-fired combustion conditions consists primarily of carbonaceous material (50-95%). Carbonaceous components on particles <0.6. μm measured by a thermal optical method showed that large fractions (52-93%) consisted of OC rather than EC, as expected. This observation was supported by thermogravimetric analysis indicating that for the air, 28% oxy, and 32% oxy conditions, 14-71% of this material may be OC volatilizing between 100. C and 550. C with the remaining 29-86% being EC/soot. However, for the 36% oxy condition, OC may comprise over 90% of the ultrafine carbon with a much smaller EC/soot contribution. These data were interpreted by considering the effects of oxy-combustion on flame attachment, ignition delay, and soot oxidation of a bituminous coal, and the effects of these processes on OC and EC emissions. Flame aerodynamics and inlet oxidant composition may influence emissions of organic hazardous air pollutants (HAPs) from a bituminous coal. During oxy-coal combustion, judicious control of inlet oxygen concentration and placement may be used to minimize organic HAP and soot emissions.

  17. Amplifying genetic logic gates.

    Science.gov (United States)

    Bonnet, Jerome; Yin, Peter; Ortiz, Monica E; Subsoontorn, Pakpoom; Endy, Drew

    2013-05-03

    Organisms must process information encoded via developmental and environmental signals to survive and reproduce. Researchers have also engineered synthetic genetic logic to realize simpler, independent control of biological processes. We developed a three-terminal device architecture, termed the transcriptor, that uses bacteriophage serine integrases to control the flow of RNA polymerase along DNA. Integrase-mediated inversion or deletion of DNA encoding transcription terminators or a promoter modulates transcription rates. We realized permanent amplifying AND, NAND, OR, XOR, NOR, and XNOR gates actuated across common control signal ranges and sequential logic supporting autonomous cell-cell communication of DNA encoding distinct logic-gate states. The single-layer digital logic architecture developed here enables engineering of amplifying logic gates to control transcription rates within and across diverse organisms.

  18. Flashlamp excited fluid laser amplified

    International Nuclear Information System (INIS)

    1976-01-01

    The patent describes a laser amplifier with chambers for containing and amplifying an intensifier medium. It serves the need for a large impulse repetition rate and high intensities as required e.g. for laser isotope separation

  19. Ultrafine-grained porous titanium and porous titanium/magnesium composites fabricated by space holder-enabled severe plastic deformation

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Yuanshen, E-mail: yuanshen.qi@monash.edu [Centre for Advanced Hybrid Materials, Department of Materials Engineering, Monash University, Clayton, Victoria 3800 (Australia); Contreras, Karla G. [Monash Institute of Medical Engineering, Faculty of Engineering, Monash University, Clayton, Victoria 3800 (Australia); Jung, Hyun-Do [Liquid Processing & Casting Technology R& D Group, Korea Institute of Industrial Technology, Incheon 406-840 (Korea, Republic of); Department of Materials Science and Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of); Kim, Hyoun-Ee [Department of Materials Science and Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of); Advanced Institutes of Convergence Technology, Seoul National University, Gwanggyo, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-270 (Korea, Republic of); Lapovok, Rimma [Centre for Advanced Hybrid Materials, Department of Materials Engineering, Monash University, Clayton, Victoria 3800 (Australia); Estrin, Yuri, E-mail: yuri.estrin@monash.edu [Centre for Advanced Hybrid Materials, Department of Materials Engineering, Monash University, Clayton, Victoria 3800 (Australia); Laboratory of Hybrid Nanostructured Materials, NUST MISiS, Moscow 119490 (Russian Federation)

    2016-02-01

    Compaction of powders by equal channel angular pressing (ECAP) using a novel space holder method was employed to fabricate metallic scaffolds with tuneable porosity. Porous Ti and Ti/Mg composites with 60% and 50% percolating porosity were fabricated using powder blends with two kinds of sacrificial space holders. The high compressive strength and good ductility of porous Ti and porous Ti/Mg obtained in this way are believed to be associated with the ultrafine grain structure of the pore walls. To understand this, a detailed electron microscopy investigation was employed to analyse the interface between Ti/Ti and Ti/Mg particles, the grain structures in Ti particles and the topography of pore surfaces. It was found that using the proposed compaction method, high quality bonding between particles was obtained. Comparing with other powder metallurgy methods to fabricate Ti with an open porous structure, where thermal energy supplied by a laser beam or high temperature sintering is essential, the ECAP process conducted at a relatively low temperature of 400 °C was shown to produce unique properties. - Highlights: • Porous Ti and porous Ti/Mg composite scaffolds were fabricated successfully. • Space holder-enabled severe plastic deformation was first used in this application. • Silicon particles as sacrificial space holders were used for the first time. • Ultrafine-grained microstructure and good bonding between particles were obtained. • Good preosteoblast cell response to as-manufactured porous Ti was achieved.

  20. Carbon supported ultrafine gold phosphorus nanoparticles as highly efficient electrocatalyst for alkaline ethanol oxidation reaction

    International Nuclear Information System (INIS)

    Li, Tongfei; Fu, Gengtao; Su, Jiahui; Wang, Yi; Lv, Yinjie; Zou, Xiuyong; Zhu, Xiaoshu; Xu, Lin; Sun, Dongmei; Tang, Yawen

    2017-01-01

    Graphical abstract: We develop a new kind of carbon supported gold-phosphorus (Au-P/C) electrocatalyst by a facile and novel phosphorus reduction method, and demonstrate the Au-P/C is a highly active and stable electrocatalyst for the ethanol oxidation reaction. - Highlights: • Au-P/C catalyst is synthesized by a facile and novel white-phosphorus reduce method. • AuP particles with ultrafine particle-size are uniformly dispersed on carbon support. • Au-P/C catalyst exhibits much higher content of P 0 than reported metal/P catalysts. • Au-P/C catalysts show excellent catalytic properties for ethanol oxidation reaction. - Abstract: Herein, we develop a new kind of carbon supported gold-phosphorus (Au-P/C) electrocatalyst for the alkaline ethanol oxidation reaction (EOR). The Au-P/C catalysts with different Au/P ratio (i.e., AuP/C, Au 3 P 2 /C and Au 4 P 3 /C) can be obtained by a facile and novel hot-reflux method with white phosphorus (P 4 ) as reductant and ethanol as solvent. The crystal structure, composition and particle-size of the Au-P/C catalysts are investigated by X-ray diffraction (XRD), Energy Dispersive Spectrometer (EDS), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), etc. The results demonstrate that Au-P/C catalysts present an alloy phase with the high content of P, ultrafine particle-size and high dispersity on carbon support, which results in excellent electrocatalytic activity and stability towards the EOR compared with that of the free-phosphorus Au/C catalyst. In addition, among the various Au-P/C catalysts with different Au/P ratio, the AuP/C sample exhibits the best electrocatalytic performance in comparison with other Au 3 P 2 /C and Au 4 P 3 /C samples.

  1. Improved-Bandwidth Transimpedance Amplifier

    Science.gov (United States)

    Chapsky, Jacob

    2009-01-01

    The widest available operational amplifier, with the best voltage and current noise characteristics, is considered for transimpedance amplifier (TIA) applications where wide bandwidth is required to handle fast rising input signals (as for time-of-flight measurement cases). The added amplifier inside the TIA feedback loop can be configured to have slightly lower voltage gain than the bandwidth reduction factor.

  2. A novel film-pore-surface diffusion model to explain the enhanced enzyme adsorption of corn stover pretreated by ultrafine grinding.

    Science.gov (United States)

    Zhang, Haiyan; Chen, Longjian; Lu, Minsheng; Li, Junbao; Han, Lujia

    2016-01-01

    Ultrafine grinding is an environmentally friendly pretreatment that can alter the degree of polymerization, the porosity and the specific surface area of lignocellulosic biomass and can, thus, enhance cellulose hydrolysis. Enzyme adsorption onto the substrate is a prerequisite for the enzymatic hydrolysis process. Therefore, it is necessary to investigate the enzyme adsorption properties of corn stover pretreated by ultrafine grinding. The ultrafine grinding pretreatment was executed on corn stover. The results showed that ultrafine grinding pretreatment can significantly decrease particle size [from 218.50 μm of sieve-based grinding corn stover (SGCS) to 17.45 μm of ultrafine grinding corn stover (UGCS)] and increase the specific surface area (SSA), pore volume (PV) and surface composition (SSA: from 1.71 m(2)/g of SGCS to 2.63 m(2)/g of UGCS, PV: from 0.009 cm(3)/g of SGCS to 0.024 m(3)/g of UGCS, cellulose surface area: from 168.69 m(2)/g of SGCS to 290.76 m(2)/g of UGCS, lignin surface area: from 91.46 m(2)/g of SGCS to 106.70 m(2)/g of UGCS). The structure and surface composition changes induced by ultrafine grinding increase the enzyme adsorption capacity from 2.83 mg/g substrate of SGCS to 5.61 mg/g substrate of UGCS. A film-pore-surface diffusion model was developed to simultaneously predict the enzyme adsorption kinetics of both the SGCS and UGCS. Satisfactory predictions could be made with the model based on high R (2) and low RMSE values (R (2) = 0.95 and RMSE = 0.16 mg/g for the UGCS, R (2) = 0.93 and RMSE = 0.09 mg/g for the SGCS). The model was further employed to analyze the rate-limiting steps in the enzyme adsorption process. Although both the external-film and internal-pore mass transfer are important for enzyme adsorption on the SGCS and UGCS, the UGCS has a lower internal-pore resistance compared to the SGCS. Ultrafine grinding pretreatment can enhance the enzyme adsorption onto corn stover by altering structure and

  3. Superior H2 production by hydrophilic ultrafine Ta2O5 engineered covalently on graphene

    International Nuclear Information System (INIS)

    Mao, Lin; Zhu, Shenmin; Shi, Dian; Chen, Yixin; Yin, Chao; Li, Yao; Zhang, Di; Ma, Jun; Chen, Zhixin

    2014-01-01

    A H 2 O 2 -mediated hydrothermal method was developed for the fabrication of hydrophilic Ta 2 O 5 /graphene composite. The composite shows a superior H 2 productivity, up to 30 mmol g −1 h −1 when used as a photocatalyst for water splitting, corresponding to an apparent quantum efficiency of 33.8% at 254 nm. This superior performance is due to the hydrophilic nature of the composite and more importantly due to the ultrafine Ta 2 O 5 nanoparticles (about 4.0 ± 1.5 nm) which are covalently bonded with the conductive graphene. The hydrophilic property of the composite is attributed to the use of H 2 O 2 in the hydrothermal process. The ultrafine size of the Ta 2 O 5 particles which are covalently bonded with the graphene sheets is attributed to the use of sonication in the synthesis process. Furthermore, the hydrophilic Ta 2 O 5 /Gr composite is durable, which is beneficial to long term photocatalysis. The strategy reported here provides a new approach to designing photocatalysts with superior performance for H 2 production. (papers)

  4. Simplified design of IC amplifiers

    CERN Document Server

    Lenk, John

    1996-01-01

    Simplified Design of IC Amplifiers has something for everyone involved in electronics. No matter what skill level, this book shows how to design and experiment with IC amplifiers. For experimenters, students, and serious hobbyists, this book provides sufficient information to design and build IC amplifier circuits from 'scratch'. For working engineers who design amplifier circuits or select IC amplifiers, the book provides a variety of circuit configurations to make designing easier.Provides basics for all phases of practical design.Covers the most popular forms for amplif

  5. Lung cancer risk of airborne particles for Italian population

    Energy Technology Data Exchange (ETDEWEB)

    Buonanno, G., E-mail: buonanno@unicas.it [Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Via Di Biasio 43, 03043 Cassino, FR (Italy); International Laboratory for Air Quality and Health, Queensland University of Technology, 2 George Street 2, 4001 Brisbane, Qld. (Australia); Giovinco, G., E-mail: giovinco@unicas.it [Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Via Di Biasio 43, 03043 Cassino, FR (Italy); Morawska, L., E-mail: morawska@qut.edu.au [International Laboratory for Air Quality and Health, Queensland University of Technology, 2 George Street 2, 4001 Brisbane, Qld. (Australia); Stabile, L., E-mail: stabile@unicas.it [Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Via Di Biasio 43, 03043 Cassino, FR (Italy)

    2015-10-15

    Airborne particles, including both ultrafine and supermicrometric particles, contain various carcinogens. Exposure and risk-assessment studies regularly use particle mass concentration as dosimetry parameter, therefore neglecting the potential impact of ultrafine particles due to their negligible mass compared to supermicrometric particles. The main purpose of this study was the characterization of lung cancer risk due to exposure to polycyclic aromatic hydrocarbons and some heavy metals associated with particle inhalation by Italian non-smoking people. A risk-assessment scheme, modified from an existing risk model, was applied to estimate the cancer risk contribution from both ultrafine and supermicrometric particles. Exposure assessment was carried out on the basis of particle number distributions measured in 25 smoke-free microenvironments in Italy. The predicted lung cancer risk was then compared to the cancer incidence rate in Italy to assess the number of lung cancer cases attributed to airborne particle inhalation, which represents one of the main causes of lung cancer, apart from smoking. Ultrafine particles are associated with a much higher risk than supermicrometric particles, and the modified risk-assessment scheme provided a more accurate estimate than the conventional scheme. Great attention has to be paid to indoor microenvironments and, in particular, to cooking and eating times, which represent the major contributors to lung cancer incidence in the Italian population. The modified risk assessment scheme can serve as a tool for assessing environmental quality, as well as setting up exposure standards for particulate matter. - Highlights: • Lung cancer risk for non-smoking Italian population due to particle inhalation. • The average lung cancer risk for Italian population is equal to 1.90×10{sup −2}. • Ultrafine particle is the aerosol metric mostly contributing to lung cancer risk. • B(a)P is the main (particle-bounded) compound

  6. Lung cancer risk of airborne particles for Italian population

    International Nuclear Information System (INIS)

    Buonanno, G.; Giovinco, G.; Morawska, L.; Stabile, L.

    2015-01-01

    Airborne particles, including both ultrafine and supermicrometric particles, contain various carcinogens. Exposure and risk-assessment studies regularly use particle mass concentration as dosimetry parameter, therefore neglecting the potential impact of ultrafine particles due to their negligible mass compared to supermicrometric particles. The main purpose of this study was the characterization of lung cancer risk due to exposure to polycyclic aromatic hydrocarbons and some heavy metals associated with particle inhalation by Italian non-smoking people. A risk-assessment scheme, modified from an existing risk model, was applied to estimate the cancer risk contribution from both ultrafine and supermicrometric particles. Exposure assessment was carried out on the basis of particle number distributions measured in 25 smoke-free microenvironments in Italy. The predicted lung cancer risk was then compared to the cancer incidence rate in Italy to assess the number of lung cancer cases attributed to airborne particle inhalation, which represents one of the main causes of lung cancer, apart from smoking. Ultrafine particles are associated with a much higher risk than supermicrometric particles, and the modified risk-assessment scheme provided a more accurate estimate than the conventional scheme. Great attention has to be paid to indoor microenvironments and, in particular, to cooking and eating times, which represent the major contributors to lung cancer incidence in the Italian population. The modified risk assessment scheme can serve as a tool for assessing environmental quality, as well as setting up exposure standards for particulate matter. - Highlights: • Lung cancer risk for non-smoking Italian population due to particle inhalation. • The average lung cancer risk for Italian population is equal to 1.90×10 −2 . • Ultrafine particle is the aerosol metric mostly contributing to lung cancer risk. • B(a)P is the main (particle-bounded) compound contributing

  7. Low-cost amplifier for alpha detection with photodiode

    Energy Technology Data Exchange (ETDEWEB)

    Domienikan, Cláudio; Costa, Priscila; Genezini, Frederico A.; Zahn, Guilherme S., E-mail: clanikan@ipen.br, E-mail: pcosta@ipen.br, E-mail: fredzini@ipen.br, E-mail: gzahn@ipen.br [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil)

    2017-07-01

    A low-cost amplifier for Hamamatsu S3590-09 PIN photodiode to be used in alpha detection is presented. This amplifier consists basically of two circuits: a pulse preamplifier and a shaper-driver. The PIN photodiode is reverse-biased and connected to a charge preamplifier input. Incident alpha particles generate a small current pulse in the photodiode. The integrating circuit of the low noise preamplifier transforms current pulse into a voltage pulse with amplitude proportional to the charge carried by the current pulse. The shaper-driver consists of a differentiator and an integrator and is responsible for filtering and further amplifying the preamplifier signal, generating a NIM-compatible energy pulse. The performance of the set photodiode-amplifier was successively tested through the use of a {sup 243}Am radioactive source. The low-cost photodiode amplifier was designed and constructed at IPEN - CNEN/SP using national components and expertise. (author)

  8. Twinning interactions induced amorphisation in ultrafine silicon grains

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Y. [School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Zhang, L.C., E-mail: liangchi.zhang@unsw.edu.au [School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Zhang, Y. [School of Mechatronics Engineering, Harbin Institute of Technology (China)

    2016-03-21

    Detailed transmission electron microscopy analysis on a severely deformed Al-Si composite material has revealed that partial dislocation slips and deformation twinning are the major plastic deformation carriers in ultrafine silicon grains. This resembles the deformation twinning activities and mechanisms observed in nano-crystalline face-centred-cubic metallic materials. While deformation twinning and amorphisation in Si were thought unlikely to co-exist, it is observed for the first time that excessive twinning and partial dislocation interactions can lead to localised solid state amorphisation inside ultrafine silicon grains.

  9. In vivo deposition of ultrafine aerosols in human nasal and oral airways

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, Hsu-Chi; Swift, D.L. [John Hopkins Univ., Baltimore, MD (United States); Simpson, S.Q. [Univ. of New Mexico, Albuquerque, NM (United States)] [and others

    1995-12-01

    The extrathoracic airways, including the nasal passage, oral passage, pharynx, and larynx, are the first targets for inhaled particles and provide an important defense for the lung. Understanding the deposition efficiency of the nasal and oral passages is therefore crucial for assessing doses of inhaled particles to the extrathoracic airways and the lung. Significant inter-subject variability in nasal deposition has been shown in recent studies by Rasmussen, T.R. et al, using 2.6 {mu}m particles in 10 human subjects and in our preliminary studies using 0.004-0.15 {mu}m particles in four adult volunteers. No oral deposition was reported in either of these studies. Reasons for the intersubject variations have been frequently attributed to the geometry of the nasal passages. The aims of the present study were to measure in vivo the nasal airway dimensions and the deposition of ultrafine aerosols in both the nasal and oral passages, and to determine the relationship between nasal airway dimensions and aerosol deposition. A statistical procedure incorporated with the diffusion theory was used to model the dimensional features of the nasal airways which may be responsible for the biological variability in particle deposition. In summary, we have correlated deposition of particles in the size range of 0.004 to 0.15 {mu}m with the nasal dimensions of each subject.

  10. In vivo deposition of ultrafine aerosols in human nasal and oral airways

    International Nuclear Information System (INIS)

    Yeh, Hsu-Chi; Swift, D.L.; Simpson, S.Q.

    1995-01-01

    The extrathoracic airways, including the nasal passage, oral passage, pharynx, and larynx, are the first targets for inhaled particles and provide an important defense for the lung. Understanding the deposition efficiency of the nasal and oral passages is therefore crucial for assessing doses of inhaled particles to the extrathoracic airways and the lung. Significant inter-subject variability in nasal deposition has been shown in recent studies by Rasmussen, T.R. et al, using 2.6 μm particles in 10 human subjects and in our preliminary studies using 0.004-0.15 μm particles in four adult volunteers. No oral deposition was reported in either of these studies. Reasons for the intersubject variations have been frequently attributed to the geometry of the nasal passages. The aims of the present study were to measure in vivo the nasal airway dimensions and the deposition of ultrafine aerosols in both the nasal and oral passages, and to determine the relationship between nasal airway dimensions and aerosol deposition. A statistical procedure incorporated with the diffusion theory was used to model the dimensional features of the nasal airways which may be responsible for the biological variability in particle deposition. In summary, we have correlated deposition of particles in the size range of 0.004 to 0.15 μm with the nasal dimensions of each subject

  11. Heterogeneous condensation for submicronic particles abatement

    OpenAIRE

    Tammaro, Marco

    2010-01-01

    It is now well established that the emission of sub-micrometric particulate matter entrained in flue gases of industry and vehicles exhausts, is one of the most critical treats for human health because of the toxicological effects of ultrafine particles on the respiratory system and their ability to cross alveoli’s membranes reaching the circulatory system too. Albeit this scenario, the traditional particle abatement devices are mainly designed and optimised to treat particles larger tha...

  12. Wideband amplifier design

    CERN Document Server

    Hollister, Allen L

    2007-01-01

    In this book, the theory needed to understand wideband amplifier design using the simplest models possible will be developed. This theory will be used to develop algebraic equations that describe particular circuits used in high frequency design so that the reader develops a ""gut level"" understanding of the process and circuit. SPICE and Genesys simulations will be performed to show the accuracy of the algebraic models. By looking at differences between the algebraic equations and the simulations, new algebraic models will be developed that include parameters originally left out of the model

  13. Building valve amplifiers

    CERN Document Server

    Jones, Morgan

    2013-01-01

    Building Valve Amplifiers is a unique hands-on guide for anyone working with tube audio equipment--as an electronics hobbyist, audiophile or audio engineer. This 2nd Edition builds on the success of the first with technology and technique revisions throughout and, significantly, a major new self-build project, worked through step-by-step, which puts into practice the principles and techniques introduced throughout the book. Particular attention has been paid to answering questions commonly asked by newcomers to the world of the valve, whether audio enthusiasts tackling their first build or

  14. The Radiation Synthesis of Ultra-Fine Powdered Carboxylated Styrene-Butadiene Rubber (UFCSBR) and Property of Nylon 6/ UFCSBR Blends

    International Nuclear Information System (INIS)

    Xu, L.

    2006-01-01

    A serial of novel ultra-fine powdered carboxylated styrene-butadiene rubber (UFCSBR) were prepared by using radiation crosslinking and spray drying method. Thereafter, these powdered rubber particles were used as toughener of nylon 6.The radiation synthesis of ultra-fine powdered rubbers were studied, moreover, the mechanical and thermal property of nylon 6/UFCSBR blends were investigated. Finally, the toughening mechanism of nylon 6 modified with ultra-fine rubber particles was discussed. The UFCSBR could be dispersed well in nylon 6 as individual particles with a diameter of 150 nm by using melt blending. The Nylon 6/UFCSBR (80/20) blend possesses higher toughness and higher thermal stability than Nylon 6/POE-g-MAH (which is most often used elastomer in toughening nylon now). The deformation mechanism of nylon 6/UFCSBR blends includes shear deformation of nylon 6 and the formation of elongated rubber particles in matrix. In addition, the UFCSBR has good interfacial compatibility with nylon 6. Therefore, the nylon 6/UFCSBR blends with good mechanical performance could be prepared in this work

  15. Superconducting digital logic amplifier

    International Nuclear Information System (INIS)

    Przybysz, J.X.

    1989-01-01

    This paper describes a superconducting digital logic amplifier for interfacing between a Josephson junction logic circuit having output current and a higher voltage semiconductor circuit input. The amplifier comprising: an input terminal for connection to a; an output terminal for connection to a semiconductor circuit input; an input, lower critical current, Josephson junction having first and second terminals; a first series string of at least three lower critical current Josephson junctions. The first series string being connected to the first terminal of the input Josephson junction such that the first series string is in series with the input Josephson junction to provide a series combination. The input terminal being connected to the first terminal of the input Josephson junction, and with the critical current of the lower critical current Josephson junctions of the input Josephson junction and the first series Josephson junctions being less than the output current of the low voltage Josephson junction circuit; a second series string of at least four higher critical current Josephson junctions. The second string being connected in parallel with the series combination to provide parallel strings having an upper common connection and a lower common connection. The lower common connection being connected to the second terminal of the input Josephson junction and the upper common connection being connected to the output terminal; and a pulsed DC current source connected the parallel strings at the upper common connection. The DC current source having a current at least equal to the critical current of the higher critical current Josephson junctions

  16. Cascade energy amplifier

    International Nuclear Information System (INIS)

    Barzilov, A.P.; Gulevich, A.V.; Kukharchuk, O.F.

    2000-01-01

    The technical problem of long-life fission product and minor actinide incineration and production of plutonium fuel in the prospective nuclear systems will arise at significant scales of nuclear power industry development. Subcritical nuclear reactors driven by extemal neutron sources (energy amplifiers) are considered as incinerators of toxicity of complete nuclear industry. In the frames of this concept, the subcritical reactor part consisting of two coupled blanket regions (inner fast neutron spectrum core and outer thermal core) driven by extemal neutron source is discussed. Two types of source are studied: spallation target and 14-MeV fusion bum of micropellets. Liquid metal Pb-Bi is considered as target material and coolant of inner fast core. Thermal core is a heavy-water subcritical reactor of the Candu-type. The fast core is protected from thermal neutrons influence with the boron shield. All reactor technologies used in this concept are tested during years of operation and commercially available. Thus, the cascade energy amplifiers have a set of advantages in comparison with traditional concepts: in energy production, in transmutation efficiency, and in economics. (authors)

  17. Formation of ultra-fine grained TiC-dispersed SUS316L by ball-milling and their consolidation by hot isostatic pressing

    International Nuclear Information System (INIS)

    Zheng, Yongjia; Yamasaki, Tohru; Fukami, Takeshi; Mitamura, Tohru; Terasawa, Mititaka

    2003-01-01

    In order to overcome the irradiation embrittlement in austenitic stainless steels, ultra-fine grained SUS316L steels with very fine TiC particles have been developed. The SUS316-TiC nanocomposite powders having 1.0 to 2.0 mass%TiC were prepared by ball-milling SUS316-TiC powder mixtures for 125h in an argon gas atmosphere. The milled powders were consolidated by hot isostatic pressing (HIP) under a pressure of 200 MPa at temperature between 700-1000degC, and the bulk materials with crystallite size ranging between 100-400 nm have been produced. The possibility of using fine-grained TiC particles for pinning grain boundaries and thereby to maintain the ultra-fine grained structures has been discussed. (author)

  18. Biocompatible and Biodegradable Ultrafine Nanoparticles of Poly(Methyl Methacrylate-co-Methacrylic Acid Prepared via Semicontinuous Heterophase Polymerization: Kinetics and Product Characterization

    Directory of Open Access Journals (Sweden)

    Henned Saade

    2016-01-01

    Full Text Available Ultrafine nanoparticles, less than 10 nm in mean diameter, of the FDA approved copolymer methyl methacrylate- (MMA- co-methacrylic acid (MAA, 2/1 (mol/mol, were prepared. The method used for the preparation of these particles stabilized in a latex containing around 11% solids includes the dosing of the monomers mixture on a micellar solution preserving monomer starved conditions. It is thought that the operation at these conditions combined with the hydrophilicity of MMA and MAA units favors the formation of ultrafine particles; the propagation reaction carried out within so small compartments renders copolymer chains rich in syndiotactic units very likely as consequence of the restricted movements of the end propagation of the chains. Because of their biocompatibility and biodegradability as well as their extremely small size these nanoparticles could be used as vehicles for improved drug delivery in the treatment of chronic-degenerative diseases.

  19. Epitaxial deposition of silver ultrafine nano-clusters on defect-free surfaces of HOPG-derived few-layer graphene in a UHV multi-chamber by in-situ STM, ex-situ XPS and ab initio calculations

    CSIR Research Space (South Africa)

    Ndlovu, GF

    2012-03-01

    Full Text Available The growth of three-dimensional ultra-fine spherical nano-particles of silver on few layers of graphene derived from highly oriented pyrolytic graphite in ultra-high vacuum were characterized using in situ scanning tunneling microscopy (STM...

  20. Cytocompatible and water stable ultrafine protein fibers for tissue engineering

    Science.gov (United States)

    Jiang, Qiuran

    This dissertation proposal focuses on the development of cytocompatible and water stable protein ultrafine fibers for tissue engineering. The protein-based ultrafine fibers have the potential to be used for biomedicine, due to their biocompatibility, biodegradability, similarity to natural extracellular matrix (ECM) in physical structure and chemical composition, and superior adsorption properties due to their high surface to volume ratio. However, the current technologies to produce the protein-based ultrafine fibers for biomedical applications still have several problems. For instance, the current electrospinning and phase separation technologies generate scaffolds composed of densely compacted ultrafine fibers, and cells can spread just on the surface of the fiber bulk, and hardly penetrate into the inner sections of scaffolds. Thus, these scaffolds can merely emulate the ECM as a two dimensional basement membrane, but are difficult to mimic the three dimensional ECM stroma. Moreover, the protein-based ultrafine fibers do not possess sufficient water stability and strength for biomedical applications, and need modifications such as crosslinking. However, current crosslinking methods are either high in toxicity or low in crosslinking efficiency. To solve the problems mentioned above, zein, collagen, and gelatin were selected as the raw materials to represent plant proteins, animal proteins, and denatured proteins in this dissertation. A benign solvent system was developed specifically for the fabrication of collagen ultrafine fibers. In addition, the gelatin scaffolds with a loose fibrous structure, high cell-accessibility and cell viability were produced by a novel ultralow concentration phase separation method aiming to simulate the structure of three dimensional (3D) ECM stroma. Non-toxic crosslinking methods using citric acid as the crosslinker were also developed for electrospun or phase separated scaffolds from these three proteins, and proved to be

  1. Shrinkage of Newly Formed Particles in an Urban Environment

    Czech Academy of Sciences Publication Activity Database

    Škrabalová, Lenka; Zíková, Naděžda; Ždímal, Vladimír

    2015-01-01

    Roč. 15, č. 4 (2015), s. 1313-1324 ISSN 1680-8584 R&D Projects: GA ČR GAP209/11/1342 Institutional support: RVO:67985858 Keywords : aerosol dynamics * ultrafine particles * particle shrinkage Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.393, year: 2015

  2. Nanoscale electromechanical parametric amplifier

    Science.gov (United States)

    Aleman, Benjamin Jose; Zettl, Alexander

    2016-09-20

    This disclosure provides systems, methods, and apparatus related to a parametric amplifier. In one aspect, a device includes an electron source electrode, a counter electrode, and a pumping electrode. The electron source electrode may include a conductive base and a flexible conductor. The flexible conductor may have a first end and a second end, with the second end of the flexible conductor being coupled to the conductive base. A cross-sectional dimension of the flexible conductor may be less than about 100 nanometers. The counter electrode may be disposed proximate the first end of the flexible conductor and spaced a first distance from the first end of the flexible conductor. The pumping electrode may be disposed proximate a length of the flexible conductor and spaced a second distance from the flexible conductor.

  3. Linear pulse amplifier

    International Nuclear Information System (INIS)

    Tjutju, R.L.

    1977-01-01

    Pulse amplifier is standard significant part of spectrometer. Apart from other type of amplification, it's a combination of amplification and pulse shaping. Because of its special purpose the device should fulfill the following : High resolution is desired to gain a high yield comparable to its actual state of condition. High signal to noise is desired to nhν resolution. High linearity to facilitate calibration. A good overload recovery, in order to the device will capable of analizing a low energy radiation which appear joinly on the high energy fields. Other expections of the device are its economical and practical use its extentive application. For that reason it's built on a standard NIM principle. Taking also into account the above mentioned considerations. High quality component parts are used throughout, while its availability in the domestic market is secured. (author)

  4. Modeling of semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Mørk, Jesper; Bischoff, Svend; Berg, Tommy Winther

    We discuss the modelling of semiconductor optical amplifiers with emphasis on their high-speed properties. Applications in linear amplification as well as ultrafast optical signal processing are reviewed. Finally, the possible role of quantum-dot based optical amplifiers is discussed.......We discuss the modelling of semiconductor optical amplifiers with emphasis on their high-speed properties. Applications in linear amplification as well as ultrafast optical signal processing are reviewed. Finally, the possible role of quantum-dot based optical amplifiers is discussed....

  5. Fast adsorption kinetics of highly dispersed ultrafine nickel/carbon nanoparticles for organic dye removal

    Science.gov (United States)

    Kim, Taek-Seung; Song, Hee Jo; Dar, Mushtaq Ahmad; Lee, Hack-Jun; Kim, Dong-Wan

    2018-05-01

    Magnetic metal/carbon nano-materials are attractive for pollutant adsorption and removal. In this study, ultrafine nickel/carbon nanoparticles are successfully prepared via electrical wire explosion processing in ethanol media for the elimination of pollutant organic dyes such as Rhodamine B and methylene blue in aqueous solutions. High specific surface areas originating from both the nano-sized particles and the existence of carbon on the surface of Ni nanoparticles enhance dye adsorption capacity. In addition to this, the excellent dispersity of Ni/C nanoparticles in aqueous dye solutions leads to superior adsorption rates. The adsorption kinetics for the removal of organic dyes by Ni/C nanoparticles agree with a pseudo-second-order model and follow Freundlich adsorption isotherm behavior.

  6. 超细涂料色浆对电泳漆涂装性能的影响%Influence of Ultrafine Colour Paste of Electrophoretic Coating on the Performance of Finishing Process

    Institute of Scientific and Technical Information of China (English)

    冒海燕; 王潮霞

    2012-01-01

    通过超声法制备了超细涂料色浆,并将其应用到阴极电泳漆中.考察了超细化前后涂料色浆的平均粒径、Zeta电位的变化,比较分析了超细涂料色浆与普通涂料色浆用于阴极电泳漆时漆液稳定性、漆膜沉积量、颜色深度、外观的区别.实验结果表明:超细涂料色浆的平均粒径仅为196 nm,Zeta电位为30 mV且分布均匀.用超细涂料色浆配制的电泳漆液具有较高的离心稳定性.相比于含普通涂料色浆的阴极电泳漆,含有超细涂料色浆的阴极电泳漆的漆膜的电沉积量稍高,而且更加均匀、平整、细腻.%The ultrafine colour paste, which was used in cathodic electrophoretic paint, was prepared via ultrasonic method. The average particle size and zeta potential of the ultrafine paint was discussed. The differences of the cathodic electrophoretic paint containing ultrafine colour paste or common colour paste, in stability of bath, deposition amount, color depth and appearance of film were analysised and compared. The results showed that the average particle size of the ultrafine colour paste was only 1% nm and Zeta potential 30 mV. The bath containing ultrafine colour paste had larger centrifugal stability. The deposite amount of the film with ultrafine colour paste was higher and the appearance was better and smoother than those of film with common colorant.

  7. Millimeter-wave power amplifiers

    CERN Document Server

    du Preez, Jaco

    2017-01-01

    This book provides a detailed review of millimeter-wave power amplifiers, discussing design issues and performance limitations commonly encountered in light of the latest research. Power amplifiers, which are able to provide high levels of output power and linearity while being easily integrated with surrounding circuitry, are a crucial component in wireless microwave systems. The book is divided into three parts, the first of which introduces readers to mm-wave wireless systems and power amplifiers. In turn, the second focuses on design principles and EDA concepts, while the third discusses future trends in power amplifier research. The book provides essential information on mm-wave power amplifier theory, as well as the implementation options and technologies involved in their effective design, equipping researchers, circuit designers and practicing engineers to design, model, analyze, test and implement high-performance, spectrally clean and energy-efficient mm-wave systems.

  8. High power X-band coaxial amplifier experiments

    International Nuclear Information System (INIS)

    Davis, T.J.; Nation, J.A.

    1991-01-01

    Studies are continuing on the development of X-band coaxial microwave amplifiers as a source for next generation linear colliders. Coaxial amplifiers employ an annular electron beam propagating between inner and outer drift tube conductors, a configuration which allows large increases in beam current over standard pencil beam amplifiers. Large average diameter systems may still be used without mode competition since TM mode cutoff frequencies are controlled by the separation between conductors. A number of amplifier configurations are being studied, all primed by a driven initial cavity which resonates around 9 GHz. Simple theory of coaxial systems and particle-in-cell simulations are presented, as well as initial experimental results using a 420 keV, 7-8 kA, 9 cm diameter annular beam

  9. Martensitic Transformation in Ultrafine-Grained Stainless Steel AISI 304L Under Monotonic and Cyclic Loading

    Directory of Open Access Journals (Sweden)

    Heinz Werner Höppel

    2012-02-01

    Full Text Available The monotonic and cyclic deformation behavior of ultrafine-grained metastable austenitic steel AISI 304L, produced by severe plastic deformation, was investigated. Under monotonic loading, the martensitic phase transformation in the ultrafine-grained state is strongly favored. Under cyclic loading, the martensitic transformation behavior is similar to the coarse-grained condition, but the cyclic stress response is three times larger for the ultrafine-grained condition.

  10. Enhanced Antifungal Bioactivity of Coptis Rhizome Prepared by Ultrafining Technology

    Directory of Open Access Journals (Sweden)

    Ping-Chung Kuo

    2014-01-01

    Full Text Available The aim of this study was to identify and quantify the bioactive constituents in the methanol extracts of Coptis Rhizome prepared by ultrafining technology. The indicator compound was identified by spectroscopic method and its purity was determined by HPLC. Moreover, the crude extracts and indicator compound were examined for their ability to inhibit the growth of Rhizoctonia solani Kühn AG-4 on potato dextrose agar plates. The indicator compound is a potential candidate as a new plant derived pesticide to control Rhizoctonia damping-off in vegetable seedlings. In addition, the extracts of Coptis Rhizome prepared by ultrafining technology displayed higher contents of indicator compound; they not only improve their bioactivity but also reduce the amount of the pharmaceuticals required and, thereby, decrease the environmental degradation associated with the harvesting of the raw products.

  11. Unraveling the atomic structure of ultrafine iron clusters

    KAUST Repository

    Wang, Hongtao

    2012-12-18

    Unraveling the atomic structures of ultrafine iron clusters is critical to understanding their size-dependent catalytic effects and electronic properties. Here, we describe the stable close-packed structure of ultrafine Fe clusters for the first time, thanks to the superior properties of graphene, including the monolayer thickness, chemical inertness, mechanical strength, electrical and thermal conductivity. These clusters prefer to take regular planar shapes with morphology changes by local atomic shuffling, as suggested by the early hypothesis of solid-solid transformation. Our observations differ from observations from earlier experimental study and theoretical model, such as icosahedron, decahedron or cuboctahedron. No interaction was observed between Fe atoms or clusters and pristine graphene. However, preferential carving, as observed by other research groups, can be realized only when Fe clusters are embedded in graphene. The techniques introduced here will be of use in investigations of other clusters or even single atoms or molecules.

  12. Self-amplifying mRNA vaccines.

    Science.gov (United States)

    Brito, Luis A; Kommareddy, Sushma; Maione, Domenico; Uematsu, Yasushi; Giovani, Cinzia; Berlanda Scorza, Francesco; Otten, Gillis R; Yu, Dong; Mandl, Christian W; Mason, Peter W; Dormitzer, Philip R; Ulmer, Jeffrey B; Geall, Andrew J

    2015-01-01

    This chapter provides a brief introduction to nucleic acid-based vaccines and recent research in developing self-amplifying mRNA vaccines. These vaccines promise the flexibility of plasmid DNA vaccines with enhanced immunogenicity and safety. The key to realizing the full potential of these vaccines is efficient delivery of nucleic acid to the cytoplasm of a cell, where it can amplify and express the encoded antigenic protein. The hydrophilicity and strong net negative charge of RNA impedes cellular uptake. To overcome this limitation, electrostatic complexation with cationic lipids or polymers and physical delivery using electroporation or ballistic particles to improve cellular uptake has been evaluated. This chapter highlights the rapid progress made in using nonviral delivery systems for RNA-based vaccines. Initial preclinical testing of self-amplifying mRNA vaccines has shown nonviral delivery to be capable of producing potent and robust innate and adaptive immune responses in small animals and nonhuman primates. Historically, the prospect of developing mRNA vaccines was uncertain due to concerns of mRNA instability and the feasibility of large-scale manufacturing. Today, these issues are no longer perceived as barriers in the widespread implementation of the technology. Currently, nonamplifying mRNA vaccines are under investigation in human clinical trials and can be produced at a sufficient quantity and quality to meet regulatory requirements. If the encouraging preclinical data with self-amplifying mRNA vaccines are matched by equivalently positive immunogenicity, potency, and tolerability in human trials, this platform could establish nucleic acid vaccines as a versatile new tool for human immunization. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Fundamentals of fast reduction of ultrafine iron ore at low temperature

    Institute of Scientific and Technical Information of China (English)

    Pei Zhao; Peimin Guo

    2008-01-01

    Fundamentals on the fast reduction of ultrafine iron ore at low temperature, including characterization of ultrafine ore, de- oxidation thermodynamics of stored-energy ultrafine ore, kinetics of iron ore deoxidation, and deoxidation mechanism, etc., and a new ironmaking process are presented in this article. Ultrafine ore concentrate with a high amount of stored energy can be produced by mechanical milling, and can be dcoxidated fast below 700℃ by either the coal-based or gas-based process. This novel process has some advantages over others: high productivity, low energy consumption, and environmental friendliness.

  14. Imaging of DNA Ultrafine Bridges in Budding Yeast

    DEFF Research Database (Denmark)

    Quevedo Rodriguez, Oliver; Lisby, Michael

    2018-01-01

    DNA ultrafine bridges (UFBs) are a type of chromatin-free DNA bridges that connect sister chromatids in anaphase and pose a threat to genome stability. However, little is known about the origin of these structures, and how they are sensed and resolved by the cell. In this chapter, we review tools...... and methods for studying UFBs by fluorescence microscopy including chemical and genetic approaches to induce UFBs in the model organism Saccharomyces cerevisiae....

  15. Ultrafine manganese dioxide nanowire network for high-performance supercapacitors.

    Science.gov (United States)

    Jiang, Hao; Zhao, Ting; Ma, Jan; Yan, Chaoyi; Li, Chunzhong

    2011-01-28

    Ultrafine MnO(2) nanowires with sub-10 nm diameters have been synthesized by a simple process of hydrothermal treatment with subsequent calcinations to form networks that exhibit an enhanced specific capacitance (279 F g(-1) at 1 A g(-1)), high rate capability (54.5% retention at 20 A g(-1)) and good cycling stability (1.7% loss after 1000 cycles).

  16. Imaging of DNA Ultrafine Bridges in Budding Yeast.

    Science.gov (United States)

    Quevedo, Oliver; Lisby, Michael

    2018-01-01

    DNA ultrafine bridges (UFBs) are a type of chromatin-free DNA bridges that connect sister chromatids in anaphase and pose a threat to genome stability. However, little is known about the origin of these structures, and how they are sensed and resolved by the cell. In this chapter, we review tools and methods for studying UFBs by fluorescence microscopy including chemical and genetic approaches to induce UFBs in the model organism Saccharomyces cerevisiae.

  17. Microstructural response of ultrafine-grained copper to fatigue loading

    Czech Academy of Sciences Publication Activity Database

    Kunz, Ludvík; Lukáš, Petr; Buksa, Michal; Wang, Q.; Zheng, M.

    2007-01-01

    Roč. 13, č. 1 (2007), s. 512-518 ISSN 1335-1532. [Metallography 2007. Stará Lesná, 02.05.2007-04.05.2007] R&D Projects: GA MŠk(CZ) 1P05ME804 Institutional research plan: CEZ:AV0Z20410507 Keywords : Ultrafine-grained copper * Fatigue * Softening/hardening Subject RIV: JG - Metallurgy

  18. Small signal microwave amplifier design

    CERN Document Server

    Grosch, Theodore

    2000-01-01

    This book explains techniques and examples for designing stable amplifiers for high-frequency applications in which the signal is small and the amplifier circuit is linear. An in-depth discussion of linear network theory provides the foundation needed to develop actual designs. Examples throughout the book will show you how to apply the knowledge gained in each chapter leading to the complex design of low noise amplifiers. Many exercises at the end of each chapter will help students to practice their skills. The solutions to these design problems are available in an accompanying solutions book

  19. Final amplifier design and mercury

    International Nuclear Information System (INIS)

    Rose, E.A.; Hanson, D.E.

    1991-01-01

    The final amplifier for the Mercury KrF excimer facility is being designed. The design exercise involves extensive modeling to predict amplifier performance. Models of the pulsed-power system, including a Child-Langmuir diode with closure, electron-beam energy deposition, KrF laser kinetics, amplified spontaneous emission (ASE), a time-dependent laser extraction in the presence of ASE are presented as a design package. The design exercise indicates that the energy objective of Phase I -- 100 joules -- will be met

  20. Research Opportunities for Materials with Ultrafine Microstructures

    Science.gov (United States)

    1989-12-31

    network with uniformly large pores (see Figure 2). An acidic DCCA, such as oxalic acid , in contrast, results in a somewhat smaller-scale network...bacteriorhodopsin macromolecule 12 FIGURE 2 Control of sol-gel processing with organic acid DCCAs 16 FIGURE 3 Densification microstructures for SiO 2 gels...monodispersed particles and hydrothermal synthesis of composites. Of recent interest in polymeric materials has been the development of rigid-rod

  1. Surfactant-Modified Ultrafine Gold Nanoparticles with Magnetic Responsiveness for Reversible Convergence and Release of Biomacromolecules.

    Science.gov (United States)

    Xu, Lu; Dong, Shuli; Hao, Jingcheng; Cui, Jiwei; Hoffmann, Heinz

    2017-03-28

    It is difficult to synthesize magnetic gold nanoparticles (AuNPs) with ultrafine sizes (coating AuNPs using magnetic particles, compounds, or ions. Here, magnetic cationic surfactants C 16 H 33 N + (CH 3 ) 3 [CeCl 3 Br] - (CTACe) and C 16 H 33 N + (CH 3 ) 3 [GdCl 3 Br] - (CTAGd) are prepared by a one-step coordination reaction, i.e., C 16 H 33 N + (CH 3 ) 3 Br - (CTABr) + CeCl 3 or GdCl 3 → CTACe or CTAGd. A simple strategy for fabricate ultrafine (gold nanoparticles (AuNPs) via surface modification with weak oxidizing paramagnetic cationic surfactants, CTACe or CTAGd, is developed. The resulting AuNPs can highly concentrate the charges of cationic surfactants on their surfaces, thereby presenting strong electrostatic interaction with negatively charged biomacromolecules, DNA, and proteins. As a consequence, they can converge DNA and proteins over 90% at a lower dosage than magnetic surfactants or existing magnetic AuNPs. The surface modification with these cationic surfactants endows AuNPs with strong magnetism, which allows them to magnetize and migrate the attached biomacromolecules with a much higher efficiency. The native conformation of DNA and proteins can be protected during the migration. Besides, the captured DNA and proteins could be released after adding sufficient inorganic salts such as at c NaBr = 50 mmol·L -1 . Our results could offer new guidance for a diverse range of systems including gene delivery, DNA transfection, and protein delivery and separation.

  2. Study of measurement methods of ultrafine aerosols surface-area for characterizing occupational exposure

    International Nuclear Information System (INIS)

    Bau, S.

    2008-12-01

    This work aims at improving knowledge on ultrafine aerosols surface-area measurement. Indeed, the development of nano-technologies may lead to occupational exposure to airborne nano-structured particles, which involves a new prevention issue. There is currently no consensus concerning what parameter (mass, surface-area, number) should be measured. However, surface-area could be a relevant metric, since it leads to a satisfying correlation with biological effects when nano-structured particles are inhaled. Hence, an original theoretical work was performed to position the parameter of surface-area in relation to other aerosol characteristics. To investigate measurement techniques of nano-structured aerosols surface-area, the experimental facility CAIMAN (Characterization of Instruments for the Measurement of Aerosols of Nano-particles) was designed and built. Within CAIMAN, it is possible to produce nano-structured aerosols with varying and controlled properties (size, concentration, chemical nature, morphology, state-of-charge), stable and reproducible in time. The generated aerosols were used to experimentally characterize the response of the instruments in study (NSAM and AeroTrak 9000 TSI, LQ1-DC Matter Engineering). The response functions measured with monodisperse aerosols show a good agreement with the corresponding theoretical curves in a large size range, from 15 to 520 nm. Furthermore, hypotheses have been formulated to explain the reasonable biases observed when measuring poly-disperse aerosols. (author)

  3. New Packaging for Amplifier Slabs

    Energy Technology Data Exchange (ETDEWEB)

    Riley, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Thorsness, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Suratwala, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Steele, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rogowski, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-03-18

    The following memo provides a discussion and detailed procedure for a new finished amplifier slab shipping and storage container. The new package is designed to maintain an environment of <5% RH to minimize weathering.

  4. Operational amplifiers theory and design

    CERN Document Server

    Huijsing, Johan

    2017-01-01

    This proven textbook guides readers to a thorough understanding of the theory and design of operational amplifiers (OpAmps). The core of the book presents systematically the design of operational amplifiers, classifying them into a periodic system of nine main overall configurations, ranging from one gain stage up to four or more stages. This division enables circuit designers to recognize quickly, understand, and choose optimal configurations. Characterization of operational amplifiers is given by macro models and error matrices, together with measurement techniques for their parameters. Definitions are given for four types of operational amplifiers depending on the grounding of their input and output ports. Many famous designs are evaluated in depth, using a carefully structured approach enhanced by numerous figures. In order to reinforce the concepts introduced and facilitate self-evaluation of design skills, the author includes problems with detailed solutions, as well as simulation exercises. Provides te...

  5. TARC: Carlo Rubbia's Energy Amplifier

    CERN Multimedia

    Laurent Guiraud

    1997-01-01

    Transmutation by Adiabatic Resonance Crossing (TARC) is Carlo Rubbia's energy amplifier. This CERN experiment demonstrated that long-lived fission fragments, such as 99-TC, can be efficiently destroyed.

  6. Enhanced performance CCD output amplifier

    Science.gov (United States)

    Dunham, Mark E.; Morley, David W.

    1996-01-01

    A low-noise FET amplifier is connected to amplify output charge from a che coupled device (CCD). The FET has its gate connected to the CCD in common source configuration for receiving the output charge signal from the CCD and output an intermediate signal at a drain of the FET. An intermediate amplifier is connected to the drain of the FET for receiving the intermediate signal and outputting a low-noise signal functionally related to the output charge signal from the CCD. The amplifier is preferably connected as a virtual ground to the FET drain. The inherent shunt capacitance of the FET is selected to be at least equal to the sum of the remaining capacitances.

  7. Low Loss Nanostructured Polymers for Chip-scale Waveguide Amplifiers.

    Science.gov (United States)

    Chen, George F R; Zhao, Xinyu; Sun, Yang; He, Chaobin; Tan, Mei Chee; Tan, Dawn T H

    2017-06-13

    On-chip waveguide amplifiers offer higher gain in small device sizes and better integration with photonic devices than the commonly available fiber amplifiers. However, on-chip amplifiers have yet to make its way into the mainstream due to the limited availability of materials with ideal light guiding and amplification properties. A low-loss nanostructured on-chip channel polymeric waveguide amplifier was designed, characterized, fabricated and its gain experimentally measured at telecommunication wavelength. The active polymeric waveguide core comprises of NaYF 4 :Yb,Er,Ce core-shell nanocrystals dispersed within a SU8 polymer, where the nanoparticle interfacial characteristics were tailored using hydrolyzed polyhedral oligomeric silsesquioxane-graft-poly(methyl methacrylate) to improve particle dispersion. Both the enhanced IR emission intensity from our nanocrystals using a tri-dopant scheme and the reduced scattering losses from our excellent particle dispersion at a high solid loading of 6.0 vol% contributed to the outstanding optical performance of our polymeric waveguide. We achieved one of the highest reported gain of 6.6 dB/cm using a relatively low coupled pump power of 80 mW. These polymeric waveguide amplifiers offer greater promise for integrated optical circuits due to their processability and integration advantages which will play a key role in the emerging areas of flexible communication and optoelectronic devices.

  8. Evidence of weak ferromagnetism in chromium(III) oxide particles

    International Nuclear Information System (INIS)

    Vazquez-Vazquez, Carlos; Banobre-Lopez, Manuel; Lopez-Quintela, M.A.; Hueso, L.E.; Rivas, J.

    2004-01-01

    The low temperature (4< T(K)<350) magnetic properties of chromium(III) oxide particles have been studied. A clear evidence of the presence of weak ferromagnetism is observed below 250 K. The magnetisation curves as a function of the applied field show coercive fields due to the canted antiferromagnetism of the particles. Around 55 K a maximum is observed in the zero-field-cooled curves; this maximum can be assumed as a blocking temperature, similarly to ultrafine ferromagnetic particles

  9. Spectroscopic amplifier for pin diode

    International Nuclear Information System (INIS)

    Alonso M, M. S.; Hernandez D, V. M.; Vega C, H. R.

    2014-10-01

    The photodiode remains the basic choice for the photo-detection and is widely used in optical communications, medical diagnostics and field of corpuscular radiation. In detecting radiation it has been used for monitoring radon and its progeny and inexpensive spectrometric systems. The development of a spectroscopic amplifier for Pin diode is presented which has the following characteristics: canceler Pole-Zero (P/Z) with a time constant of 8 μs; constant gain of 57, suitable for the acquisition system; 4th integrator Gaussian order to waveform change of exponential input to semi-Gaussian output and finally a stage of baseline restorer which prevents Dc signal contribution to the next stage. The operational amplifier used is the TLE2074 of BiFET technology of Texas Instruments with 10 MHz bandwidth, 25 V/μs of slew rate and a noise floor of 17 nv/(Hz)1/2. The integrated circuit has 4 operational amplifiers and in is contained the total of spectroscopic amplifier that is the goal of electronic design. The results show like the exponential input signal is converted to semi-Gaussian, modifying only the amplitude according to the specifications in the design. The total system is formed by the detector, which is the Pin diode, a sensitive preamplifier to the load, the spectroscopic amplifier that is what is presented and finally a pulse height analyzer (Mca) which is where the spectrum is shown. (Author)

  10. Inhaled Pollutants: The Molecular Scene behind Respiratory and Systemic Diseases Associated with Ultrafine Particulate Matter

    Directory of Open Access Journals (Sweden)

    Hussein Traboulsi

    2017-01-01

    Full Text Available Air pollution of anthropogenic origin is largely from the combustion of biomass (e.g., wood, fossil fuels (e.g., cars and trucks, incinerators, landfills, agricultural activities and tobacco smoke. Air pollution is a complex mixture that varies in space and time, and contains hundreds of compounds including volatile organic compounds (e.g., benzene, metals, sulphur and nitrogen oxides, ozone and particulate matter (PM. PM0.1 (ultrafine particles (UFP, those particles with a diameter less than 100 nm (includes nanoparticles (NP are considered especially dangerous to human health and may contribute significantly to the development of numerous respiratory and cardiovascular diseases such as chronic obstructive pulmonary disease (COPD and atherosclerosis. Some of the pathogenic mechanisms through which PM0.1 may contribute to chronic disease is their ability to induce inflammation, oxidative stress and cell death by molecular mechanisms that include transcription factors such as nuclear factor κB (NF-κB and nuclear factor (erythroid-derived 2-like 2 (Nrf2. Epigenetic mechanisms including non-coding RNA (ncRNA may also contribute towards the development of chronic disease associated with exposure to PM0.1. This paper highlights emerging molecular concepts associated with inhalational exposure to PM0.1 and their ability to contribute to chronic respiratory and systemic disease.

  11. Ultra-Fine Friction Grinding of Sunflower Kernels – Thereof Tahini and Halva Production and Rheological Characterization

    Directory of Open Access Journals (Sweden)

    Emil RACOLŢA

    2016-11-01

    Full Text Available Tahini is a paste obtained by milling the roasted sunflower kernel. Usually, a time and energy consuming two-steps process is involved, a three-roll refiner and a beating machine. The aim of this work was to identify and test a milling process for roasted sunflower kernels with lower time and energy consumption. Different particle size sunflower tahini and halva samples were produced by Ultra-Fine Friction Grinding machine Masuko Sangyo “Supermasscolloider” MKCA6-2 and compared to standard technology. The rheological properties of tahini and textural parameters of halva were assessed. Rheological analysis revealed that all tahini samples produced by “Supermasscolloider” showed a different viscosity profile, as compared to control, the sample milled with the gap set at 100µm being the most viscous and the one at 200µm being the most fluid. When testing the halva samples texture, the sample obtained from the tahini milled at 200µm was clearly highlighted as having the lowest hardness values, while the other samples showed similar texture profiles. The feasibility of using an Ultra-Fine Friction Grinding machine for obtaining sunflower tahini and thereof halva with improved textural properties, was assessed successfully.

  12. [Ultra-Fine Pressed Powder Pellet Sample Preparation XRF Determination of Multi-Elements and Carbon Dioxide in Carbonate].

    Science.gov (United States)

    Li, Xiao-li; An, Shu-qing; Xu, Tie-min; Liu, Yi-bo; Zhang, Li-juan; Zeng, Jiang-ping; Wang, Na

    2015-06-01

    The main analysis error of pressed powder pellet of carbonate comes from particle-size effect and mineral effect. So in the article in order to eliminate the particle-size effect, the ultrafine pressed powder pellet sample preparation is used to the determination of multi-elements and carbon-dioxide in carbonate. To prepare the ultrafine powder the FRITSCH planetary Micro Mill machine and tungsten carbide media is utilized. To conquer the conglomeration during the process of grinding, the wet grinding is preferred. The surface morphology of the pellet is more smooth and neat, the Compton scatter effect is reduced with the decrease in particle size. The intensity of the spectral line is varied with the change of the particle size, generally the intensity of the spectral line is increased with the decrease in the particle size. But when the particle size of more than one component of the material is decreased, the intensity of the spectral line may increase for S, Si, Mg, or decrease for Ca, Al, Ti, K, which depend on the respective mass absorption coefficient . The change of the composition of the phase with milling is also researched. The incident depth of respective element is given from theoretical calculation. When the sample is grounded to the particle size of less than the penetration depth of all the analyte, the effect of the particle size on the intensity of the spectral line is much reduced. In the experiment, when grounded the sample to less than 8 μm(d95), the particle-size effect is much eliminated, with the correction method of theoretical α coefficient and the empirical coefficient, 14 major, minor and trace element in the carbonate can be determined accurately. And the precision of the method is much improved with RSD element, the fluorescence yield is low and the interference is serious. With the manual multi-layer crystal PX4, coarse collimator, empirical correction, X-ray spectrometer can be used to determine the carbon dioxide in the carbonate

  13. Health effects of exhaust particles

    Energy Technology Data Exchange (ETDEWEB)

    Pihlava, T.; Uuppo, M.; Niemi, S.

    2013-11-01

    This report introduces general information about diesel particles and their health effects. The purpose of this report is to introduce particulate matter pollution and present some recent studies made regarding the health effects of particulate matter. The aim is not to go very deeply into the science, but instead to keep the text understandable for the average layman. Particulate matter is a complex mixture of extremely small particles and liquid droplets. These small particles are made up of a number of components that include for example acids, such as nitrates and sulphates, as well as organic chemicals, metals and dust particles from the soil. Particulate matter comes from several sources, such as transportation emissions, industrial emissions, forest fires, cigarette smoke, volcanic ash and climate variations. Particles are divided into coarse particles with diameters less than 10 ..m, fine particles with diameters smaller than 2.5 ..m and ultra-fine particles with diameters less than 0.1 ..m. The particulate matter in diesel exhaust gas is a highly complex mixture of organic, inorganic, solid, volatile and partly volatile compounds. Many of these particles do not form until they reach the air. Many carcinogenic compounds have been found in diesel exhaust gas and it is considered carcinogenic to humans. Particulate matter can cause several health effects, such as premature death in persons with heart or lung disease, cancer, nonfatal heart attacks, irregular heartbeat, aggravated asthma, decreased lung function and an increase in respiratory symptoms, such as irritation of the airways, coughing or difficulty breathing. It is estimated that in Finland about 1300 people die prematurely due to particles and the economic loss in the EU due to the health effects of particles can be calculated in the billions. Ultra-fine particles are considered to be the most harmful to human health. Ultrafine particles usually make the most of their quantity and surface area

  14. Surface structure and adsorption properties of ultrafine porous carbon fibers

    International Nuclear Information System (INIS)

    Song Xiaofeng; Wang Ce; Zhang Dejiang

    2009-01-01

    Ultrafine porous carbon fibers (UPCFs) were successfully synthesized by chemical activation of electrospun polyacrylonitrile fibers. In the current approach, potassium hydroxide was adopted as activation reagent. UPCFs were systematically evaluated by scanning electron microscope and nitrogen adsorption. The mass ratio of potassium hydroxide to preoxidized fibers, activation temperature and activation time are crucial for producing high quality UPCFs. The relationships between porous structure and process parameters are explored. UPCFs were applied as adsorbent for nitrogen monoxide to be compared with commercial porous carbon fibers.

  15. Dielectric waveguide amplifiers and lasers

    NARCIS (Netherlands)

    Pollnau, Markus

    The performance of semiconductor amplifiers and lasers has made them the preferred choice for optical gain on a micro-chip. In the past few years, we have demonstrated that also rare-earth-ion-doped dielectric waveguides show remarkable performance, ranging from a small-signal gain per unit length

  16. Directly electrospun ultrafine nanofibres with Cu grid spinneret

    International Nuclear Information System (INIS)

    Li Wenwang; Zheng Gaofeng; Wang Xiang; Wang Lingyun; Wang Han; Sun Daoheng; Zhang Yulong; Li Lei

    2011-01-01

    A hydrophobic Cu grid was used as an electrospinning spinneret to fabricate ultrafine organic nanofibres. The Cu grid used in this study was that which holds samples in TEM. Due to the hydrophobic surface and larger contact angle of the electrospinning solution on the Cu grid surface, the solution flow was divided into several finer ones by the holes in the Cu grid instead of accumulating. Each finer flow was stretched into individual jets and established a multi-jet mode by the electrical field force. The finer jets played an important role in decreasing the diameter of the nanofibre. The charge repulsion force among charged jets enhanced the whipping instability motion of the liquid jets, which improved the uniformity of the nanofibre and decreased the diameter of the nanofibre. An ultrafine uniform nanofibre of diameter less than 80 nm could be fabricated directly with the novel Cu grid spinneret without any additive. This study provided a unique way to promote the application of one-dimensional organic nanostructures in micro/nanosystems.

  17. Preparation of ultra-fine powders from polysaccharide-coated solid lipid nanoparticles and nanostructured lipid carriers by innovative nano spray drying technology.

    Science.gov (United States)

    Wang, Taoran; Hu, Qiaobin; Zhou, Mingyong; Xue, Jingyi; Luo, Yangchao

    2016-09-10

    In this study, five polysaccharides were applied as natural polymeric coating materials to prepare solid lipid nanoparticles (SLN) and nanostructure lipid carriers (NLC), and then the obtained lipid colloidal particles were transformed to solid powders by the innovative nano spray drying technology. The feasibility and suitability of this new technology to generate ultra-fine lipid powder particles were evaluated and the formulation was optimized. The spray dried SLN powder exhibited the aggregated and irregular shape and dimension, but small, uniform, well-separated spherical powder particles of was obtained from NLC. The optimal formulation of NLC was prepared by a 20-30% oleic acid content with carrageenan or pectin as coating material. Therefore, nano spray drying technology has a potential application to produce uniform, spherical, and sub-microscale lipid powder particles when the formulation of lipid delivery system is appropriately designed. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. CMOS Current-mode Operational Amplifier

    DEFF Research Database (Denmark)

    Kaulberg, Thomas

    1992-01-01

    current-mode feedback amplifier or a constant bandwidth in a transimpedance feedback amplifier. The amplifier is found to have a gain bandwidth product of 8 MHz, an offset current of 0.8 ¿A (signal-range ±700¿A) and a (theoretically) unlimited slew-rate. The amplifier is realized in a standard CMOS 2......A fully differential-input differential-output current-mode operational amplifier (COA) is described. The amplifier utilizes three second generation current-conveyors (CCII) as the basic building blocks. It can be configured to provide either a constant gain-bandwidth product in a fully balanced...

  19. A CMOS current-mode operational amplifier

    DEFF Research Database (Denmark)

    Kaulberg, Thomas

    1993-01-01

    current-mode feedback amplifier or a constant bandwidth in a transimpedance feedback amplifier. The amplifier is found to have a gain-bandwidth product of 3 MHz, an offset current of 0.8 μA (signal range ±700 μA), and a (theoretically) unlimited slew rate. The amplifier is realized in a standard CMOS 2......A fully differential-input, differential-output, current-mode operational amplifier (COA) is described. The amplifier utilizes three second-generation current conveyors (CCIIs) as the basic building blocks. It can be configured to provide either a constant gain-bandwidth product in a fully balanced...

  20. Amplified spontaneous emissions in a high-gain laser amplifier

    International Nuclear Information System (INIS)

    Osada, Hidenori; Gamo, Hideya.

    1978-01-01

    The gain and line-narrowing of the amplified spontaneous emissions(ASE) in a partially homogeneous high-gain Xe 3.51 μm laser amplifier were studied theoretically and experimentally with emphasis of saturation effect. The unidirectionally travelling ASE was generated by conveniently using optical isolators and used as a broadband radiation source. It has properties of 10 μW/mm 2 in intensity with fluctuation of less than 1% in 5 hours, 43.5 MHz of the linewidth and 1.0 x 10 -3 radians of beam divergence. The measured saturation intensity was 4.85 μW/mm 2 and a small signal gain was 0.1 cm -1 . The theoretical prediction of the line-narrowing shows reasonablly good agreement with the measured one. (author)

  1. Features of ultrafine-grained structure forming in Zr-1Nb alloy

    Energy Technology Data Exchange (ETDEWEB)

    Stepanova, Ekaterina N.; Prosolov, Konstantin A. [National Research Tomsk Polytechnic University, Tomsk (Russian Federation); Grabovetskaya, Galina P.; Mishin, Ivan P. [Institute of Strength Physics and Materials Science of Siberian Branch of Russian Academy of Sciences, Tomsk (Russian Federation)

    2013-07-01

    Ultrafine-grained structure forming by the method combined reversible hydrogenation and hot pressing in Zr-1Nb alloy was investigated. Preliminary hydrogenation to concentrations of (0.14–0.4) % at 873 K is found to lead to yield strength decreasing in Zr-1Nb alloy during hot pressing by 1,5–2 times. During uniaxial compression at (70–72) % under isothermal conditions at a temperature of 873 K in Zr-1Nb alloy, hydrogenated to concentration of 0.22 %, homogeneous ultrafine grained structure with an average grain size of 0,4 P m was formed. Key words: zirconium alloy, ultrafine-grained structure, hydrogen.

  2. Study of the sintering behavior of fine, ultrafine and nanocrystalline WC-CO mixtures obtained by high energy milling

    International Nuclear Information System (INIS)

    Salvador, M. D.; Bonache, V.; Amigo, V.; Busquets, D.

    2008-01-01

    In this work the sintering behaviour of fine, ultrafine and nanocrystalline WC-12Co mixtures obtained by high energy milling, as well commercial nano powders, have been studied, in order to evaluate the effect of the particle size and the powder processing, in the densification, microstructural development and mechanical properties of the final product. The consolidation of the mixtures has been made by uniaxial pressing and sintering in vacuum, and by hot isostatic pressing. The sintered materials have been evaluated by measures of density, hardness and indentation fracture toughness, and micro structurally characterized by optical microscopy and scanning and transmission electronic microscopy (SEM and TEM). The results show the improvements in resistant behaviour of the materials obtained from nanocrystalline powders, in spite of the grain growth experienced during the sintering. The best results were obtained for the milling nanocrystalline material, which presents values of hardness higher than 180 HV. (Author) 46 refs

  3. Sol-gel auto-combustion synthesis and properties of Co2Z-type hexagonal ferrite ultrafine powders

    Science.gov (United States)

    Liu, Junliang; Yang, Min; Wang, Shengyun; Lv, Jingqing; Li, Yuqing; Zhang, Ming

    2018-05-01

    Z-type hexagonal ferrite ultrafine powders with chemical formulations of (BaxSr1-x)3Co2Fe24O41 (x varied from 0.0 to 1.0) have been synthesized by a sol-gel auto-combustion technique. The average particle sizes of the synthesized powders ranged from 2 to 5 μm. The partial substitution of Ba2+ by Sr2+ led to the shrinkage of the crystal lattices and resulted in changes in the magnetic sub-lattices, which tailored the static and dynamic magnetic properties of the as-synthesized powders. As the substitution ratio of Ba2+ by Sr2+, the saturation magnetization of the synthesized powders almost consistently increased from 43.3 to 56.1 emu/g, while the real part of permeability approached to a relatively high value about 2.2 owing to the balance of the saturation magnetization and magnetic anisotropy field.

  4. Preparation and characterization of ultrafine alumina via sol-gel polymeric route

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, D.M. [Ceramic Department, National Research Centre, Dokki, Cairo (Egypt); Abu-Ayana, Y.M. [Polymers and Pigments Department, National Research Centre, Dokki, Cairo (Egypt)], E-mail: yosreya20@gmail.com

    2008-10-15

    Ultrafine alumina powder was prepared through resin formation between urea and formaldehyde. Aluminium stearate soap was introduced during resin preparation. Ethylene glycol was used to terminate the thermosetting reaction. Calcination of the product was carried out at 700, 1000, 1100, 1300 and 1400 deg. C to obtain aluminium oxide. IR and Raman spectroscopic analysis indicated the occupation of Al{sup 3+} at different sites in the polymer network (C=O, -NH{sub 2}, C-O, -NH, and -CH{sub 2}OH). X-ray diffraction of powder calcined at 1000 deg. C revealed the presence of a mixture of {alpha}- and {theta}-alumina together, while a mixture of {alpha}- and {beta}-alumina phases were obtained on calcination at 1400 deg. C. Transmission electron microscope (TEM) examination of the powder fired at 700 deg. C showed uniform grains in the form of clusters with average size between 22.02 and 30.5 nm. Clusters are multi-particles as evident from the electron diffraction pattern. Crystallite size of alumina powder calcined at 1000 deg. C was found to be {approx}25.67 nm, while that of powder calcined at1400 deg. C was {approx}30.52 nm. The calculated specific surface area of alumina powder calcined at 1000 deg. C was 59.17 m{sup 2} g{sup -1}, while that calcined at 1400 deg. C was 49.77 m{sup 2} g{sup -1}.

  5. Effect of gamma irradiation on properties of ultrafine rubbers as toughening filler in polybenzoxazine

    Science.gov (United States)

    Taewattana, Rapiphan; Jubsilp, Chanchira; Suwanmala, Phiriyatorn; Rimdusit, Sarawut

    2018-04-01

    Three types of ultrafine fully vulcanized powdered rubbers (UFRs), i.e. natural rubber (NR), carboxylated nitrile-butadiene rubber (XNBR), and carboxylated styrene-butadiene rubber (XSBR) were prepared by combined technology between gamma irradiation for crosslinking and spray drying. The effects of doses in a range of 0-250 kGy on swelling ratio, crosslink density, and thermal stability of UFRs were investigated. Smaller particle size of UFRs was obtained at higher dose. A decrease in the swelling ratio and an increase in crosslink density were well corresponded to crosslinking effect related with absorbed dose. The increase in dose was also found to improve thermal performance of URFs. The influence of irradiated UFRs on impact resistance and glass transition temperature (Tg) of polybenzoxazine composites was also evaluated. The highest impact resistance of the composites belonged to the composite filled with irradiated UFXNBR at 200 kGy. While the significantly enhanced Tg of the composite was obtained by an addition of irradiated UFRs with higher doses, i.e. Tg = 173 °C for the composite filled with irradiated UFXNBR at 250 kGy. As a consequence, the UFRs can be used to effectively modify thermal and mechanical properties, especially impact resistance of polybenzoxazine composites.

  6. Single conversion stage amplifier - SICAM

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.

    2005-12-15

    This Ph.D. thesis presents a thorough analysis of the so called SICAM - SIngle Converter stage AMplifier approach to building direct energy conversion audio power amplifiers. The mainstream approach for building isolated audio power amplifiers today consists of isolated DC power supply and Class D amplifier, which essentially represents a two stage solution, where each of the components can be viewed as separate and independent part. The proposed SICAM solution strives for direct energy conversion from the mains to the audio output, by dedicating the operation of the components one to another and integrating their functions, so that the final audio power amplifier represents a single-stage topology with higher efficiency, lower volume, less board space, lower component count and subsequently lower cost. The SICAM approach is both applicable to non-isolated and isolated audio power amplifiers, but the problems encountered in these two cases are different. Non-isolated SICAM solutions are intended for both AC mains-connected and battery-powered devices. In non-isolated mains-connected SICAMs the main idea is to simplify the power supply or even provide integrated power factor correction (PFC) functions, while still maintaining low component stress and good audio performance by generally decreasing the input voltage level to the Class D audio power amplifier. On the other hand, non-isolated battery-powered SICAMs have to cope with the ever changing battery voltage and provide output voltage levels which are both lower and higher than the battery voltage, while still being simple and single-stage energy conversion solutions. In isolated SICAMs the isolation transformer adjusts the voltage level on the secondary side to the desired level, so the main challenges here are decreasing the size of the magnetic core and reducing the number and size of bulky reactive components as much as possible. The main focus of this thesis is directed towards the isolated SICAMs and

  7. Tumor necrosis factor-alpha release from rat pulmonary leukocytes exposed to ultrafine cobalt: in vivo and in vitro studies

    International Nuclear Information System (INIS)

    Zhang Qunwei; Kusaka, Yukinori; Sato, Kazuhiro; Wang Deweng; Donaldson, Kenneth

    1999-01-01

    Ultrafine cobalt (Uf-Co), one of the new category of ultrafine particles, is generated in some industrial situations and it also exists in environmental particles. The aim of this study was to investigate the ability of rat pulmonary leukocytes to release tumor necrosis factor alpha (TNF-alpha) after exposure to Uf-Co in vivo and in vitro. Rats were intratracheally instilled with 1 mg of Uf-Co, and then wet lung weight and bronchoalveolar lavage fluid (BASF) profile were analysed 1, 3, 7, 15, and 30 days later. The effects of Uf-Co on indices that can be presumed to reflect epithelial injury and permeability (lactate dehydrogenase (LDH) and total protein (TP)) were increased throughout the 30 day post-exposure period. Furthermore, at 3 days after exposure, leukocytes were collected by bronchoalveolar lavage (BAL). After 3, 6, 12, 24, 48, and 72 hours of incubation, TNF-alpha in supernatants were determined by ELISA method. The results showed that TNF-alpha secretion by activated leukocytes from rats instilled with Uf-Co was significantly higher than that of the controls. BAL leucocytes from the lung of exposed rats revealed time-and dose-related increases in TNF-alpha release. In conclusion, our results reveal, for the first time to our knowledge, that exposure to Uf-Co can stimulate leukocytes to secrete TNF-alpha. These data suggest that the TNF-alpha release from pulmonary leukocytes probably plays a role in the pathogenesis of 'cobalt lung'. (author)

  8. Analog circuit design designing high performance amplifiers

    CERN Document Server

    Feucht, Dennis

    2010-01-01

    The third volume Designing High Performance Amplifiers applies the concepts from the first two volumes. It is an advanced treatment of amplifier design/analysis emphasizing both wideband and precision amplification.

  9. Higher order mode optical fiber Raman amplifiers

    DEFF Research Database (Denmark)

    Rottwitt, Karsten; Friis, Søren Michael Mørk; Usuga Castaneda, Mario A.

    2016-01-01

    We review higher order mode Raman amplifiers and discuss recent theoretical as well as experimental results including system demonstrations.......We review higher order mode Raman amplifiers and discuss recent theoretical as well as experimental results including system demonstrations....

  10. Contribution from biogenic organic compounds to particle growth during the 2010 BEACHON-ROCS campaign in a Colorado temperate needleleaf forest

    DEFF Research Database (Denmark)

    Zhou, L.; Gierens, R.; Sogachev, Andrey

    2015-01-01

    of the oxidation products of monoterpenes and 2-Methyl-3-buten-2-ol (MBO). Monoterpene oxidation products are shown to influence the nighttime particle loadings significantly, while their concentrations are insufficient to grow the particles during the day. The growth of ultrafine particles in the daytime appears...

  11. SPS RF System Amplifier plant

    CERN Multimedia

    1977-01-01

    The picture shows a 2 MW, 200 MHz amplifier plant with feeder lines. The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities. Initially only two cavities were installed, a third cavity was installed in 1978 and a forth one in 1979. The number of power amplifiers was also increased: to the first 2 MW plant a second 2 MW plant was added and by end 1979 there were 8 500 kW units combined in pairs to feed each of the 4 cavities with up to about 1 MW RF power, resulting in a total accelerating voltage of about 8 MV. See also 7412016X, 7412017X, 7411048X.

  12. Challenges in higher order mode Raman amplifiers

    DEFF Research Database (Denmark)

    Rottwitt, Karsten; Nielsen, Kristian; Friis, Søren Michael Mørk

    2015-01-01

    A higher order Raman amplifier model that take random mode coupling into account ispresented. Mode dependent gain and signal power fluctuations at the output of the higher order modeRaman amplifier are discussed......A higher order Raman amplifier model that take random mode coupling into account ispresented. Mode dependent gain and signal power fluctuations at the output of the higher order modeRaman amplifier are discussed...

  13. European Research on THz Vacuum Amplifiers

    DEFF Research Database (Denmark)

    Brunetti, F.; Cojocarua, C.-S.; de Rossi, A.

    2010-01-01

    The OPTHER (OPtically Driven TeraHertz AmplifiERs) project represents a considerable advancement in the field of high frequency amplification. The design and realization of a THz amplifier within this project is a consolidation of efforts at the international level from the main players...... of the European research, academy and industry in vacuum electronics. This paper describes the status of the project and progress towards the THz amplifier realization....

  14. Integrated amplifying circuit with MOS transistors

    Energy Technology Data Exchange (ETDEWEB)

    Baylac, B; Merckel, G; Meunier, P

    1974-01-25

    The invention relates to a feedback-pass-band amplifier with MOS-transistors. The differential stage of conventional amplifiers is changed into an adding state, whereas the differential amplification stages are changed into amplifier inverter stages. All MOS transistors used in that amplifier are of similar configuration and are interdigitized, whereby the operating speed dispersion is reduced. This can be applied to obtaining a measurement channel for proportional chambers.

  15. NASA developments in solid state power amplifiers

    Science.gov (United States)

    Leonard, Regis F.

    1990-01-01

    Over the last ten years, NASA has undertaken an extensive program aimed at development of solid state power amplifiers for space applications. Historically, the program may be divided into three phases. The first efforts were carried out in support of the advanced communications technology satellite (ACTS) program, which is developing an experimental version of a Ka-band commercial communications system. These first amplifiers attempted to use hybrid technology. The second phase was still targeted at ACTS frequencies, but concentrated on monolithic implementations, while the current, third phase, is a monolithic effort that focusses on frequencies appropriate for other NASA programs and stresses amplifier efficiency. The topics covered include: (1) 20 GHz hybrid amplifiers; (2) 20 GHz monolithic MESFET power amplifiers; (3) Texas Instruments' (TI) 20 GHz variable power amplifier; (4) TI 20 GHz high power amplifier; (5) high efficiency monolithic power amplifiers; (6) GHz high efficiency variable power amplifier; (7) TI 32 GHz monolithic power amplifier performance; (8) design goals for Hughes' 32 GHz variable power amplifier; and (9) performance goals for Hughes' pseudomorphic 60 GHz power amplifier.

  16. A pulse amplifier for nuclear instrumentation

    International Nuclear Information System (INIS)

    Martin, D.; Cliff, P.

    1987-01-01

    A Class-A 1 Watt amplifier has been designed and optimized for nanosecond pulses. Spanning .01MHz to 1300Mhz, signal gain is 26dB with gain flatness of 1dB. The amplifier drive +- 10 volts across 500 with 350ps risetime. Each amplifier is housed in a 2-wide NIM

  17. Remote Acquisition Amplifier For 50-Ohm Cable

    Science.gov (United States)

    Amador, Jose J.

    1995-01-01

    Buffer-amplifier unit designed to drive 50-Ohm cables up to 100 ft. (30 m) long, compensating for attenuation in cables and enabling remote operation of oscilloscopes. Variable resistor provides for adjustment of gain of amplifier, such that overall gain from input terminals of amplifier to output end of cable set to unity.

  18. [A technological study on the extraction of ultra-fine powder of Panax notoginsen].

    Science.gov (United States)

    Huang, Yaohai; Huang, Mingqing; Zeng, Huifang; Guo, Wei; Xi, Ping

    2005-12-01

    To investigate the extraction of ultra-fine powder Panax notoginsen. The extraction rate of ginseng saponin Rg1, Re, Rb1, notoginseng saponin R1 and filtrated time were determined by alcoholic and aqueous extraction of Panax notoginsen in tablet, coarse powder, ultra-fine powder and recostitution granules of ultra-fine powder. The filtered time of ultra-fine powder of Panax notoginsen extraction and that of the tablet of Panax notoginsen extraction were similar, while the extraction rates of various saponins of it were high. The method of aqueous extrction in ltra-fine powder of Panax notoginsen is easy in filtrationer, higher in extraction rate of Panax notoginsen and lower in production cost.

  19. On tension-compression asymmetry in ultrafine-grained and nanocrystalline metals

    KAUST Repository

    Gurses, Ercan; El Sayed, Tamer S.

    2010-01-01

    We present a physically motivated computational study explaining the tension/compression (T/C) asymmetry phenomenon in nanocrystalline (nc) and ultrafine-grained (ufg) face centered cubic (fcc) metals utilizing a variational constitutive model where

  20. Preparation of Ni-C Ultrafine Composite from Waste Material

    Directory of Open Access Journals (Sweden)

    Mahmoud A. Rabah

    2017-06-01

    Full Text Available This work depicts the preparation of Ni-C ultrafine composite from used engine oil. The used oil was emulsified with detergent loaded with Ni (OH2. The loaded emulsion was sprayed on electric plasma generated between two C electrodes to a DC main 28 V and 70-80 A. The purged Ni-doped carbon fume was trapped on a polymer film moistened with synthetic adhesive to fix the trapped smoke. Characterization of the deposit was made using SEM. XRD examined the crystal morphology. Carbon density in the cloud was calculated. The average size and thickness of the deposited composite is 120-160 nm. Aliphatic hydrocarbons readily decompose to gaseous products. Solid carbon smoke originates from aromatic compounds. Plasma heat blasts the oil in short time to decompose in one step.

  1. An ultra-fine group slowing down benchmark

    International Nuclear Information System (INIS)

    Ganapol, B. D.; Maldonado, G. I.; Williams, M. L.

    2009-01-01

    We suggest a new solution to the neutron slowing down equation in terms of multi-energy panels. Our motivation is to establish a computational benchmark featuring an ultra-fine group calculation, where the number of groups could be on the order of 100,000. While the CENTRM code of the SCALE code package has been shown to adequately treat this many groups, there is always a need for additional verification. The multi panel solution principle is simply to consider the slowing down region as sub regions of panels, with each panel a manageable number of groups, say 100. In this way, we reduce the enormity of dealing with the entire spectrum all at once by considering many smaller problems. We demonstrate the solution in the unresolved U3o8 resonance region. (authors)

  2. Nanocrystalline and ultrafine grain copper obtained by mechanical attrition

    Directory of Open Access Journals (Sweden)

    Rodolfo Rodríguez Baracaldo

    2010-01-01

    Full Text Available This article presents a method for the sample preparation and characterisation of bulk copper having grain size lower than 1 μm (ultra-fine grain and lower than 100 nm grain size (nanocrystalline. Copper is initially manufactured by a milling/alloying me- chanical method thereby obtaining a powder having a nanocrystalline structure which is then consolidated through a process of warm compaction at high pressure. Microstructural characterisation of bulk copper samples showed the evolution of grain size during all stages involved in obtaining it. The results led to determining the necessary conditions for achieving a wide range of grain sizes. Mechanical characterisation indicated an increase in microhardness to values of around 3.40 GPa for unconsolida- ted nanocrystalline powder. Compressivee strength was increased by reducing the grain size, thereby obtaining an elastic limit of 650 MPa for consolidated copper having a ~ 62 nm grain size.

  3. Application of an Ultrafine Shearing Method for the Extraction of C-Phycocyanin from Spirulina platensis

    Directory of Open Access Journals (Sweden)

    Jianfeng Yu

    2017-11-01

    Full Text Available Cell disruption is an important step during the extraction of C-phycocyanin from Spirulina platensis. An ultrafine shearing method is introduced and combined with soaking and ultrasonication to disrupt the cell walls of S. platensis efficiently and economically. Five kinds of cell disruption method, including soaking, ultrasonication, freezing-thawing, soaking-ultrafine shearing and soaking-ultrafine shearing-ultrasonication were applied to break the cell walls of S. platensis. The effectiveness of cell breaking was evaluated based on the yield of the C-phycocyanin. The results show that the maximum C-phycocyanin yield was 9.02%, achieved by the soaking-ultrafine shearing-ultrasonication method, followed by soaking (8.43%, soaking-ultrafine shearing (8.89%, freezing and thawing (8.34%, and soaking-ultrasonication (8.62%. The soaking-ultrafine shearing-ultrasonication method is a novel technique for breaking the cell walls of S. platensis for the extraction of C-phycocyanin.

  4. Submicron and ultrafine grained hardmetals for microdrills and metal cutting inserts

    International Nuclear Information System (INIS)

    Gille, G.; Szesny, B.; Dreyer, K.; Berg, H. van den; Schidt, J.; Gestrich, T.; Leitner, G.

    2001-01-01

    Although round tools as carbide drills and mills are dominating by far the application of submicron and ultrafine hardmetals the consumption for PCB microdrills had the strongest growth rate over the last decade. This paper deals with the latest developments of ultrafine hardmetals and their application for PCB microdrills and metal cutting inserts. Based on optimized processing and properties such as hardness, hot hardness, toughness, strength and wear resistance a new generation of microdrills is presented. In particular the failure probability of the microdrills could be considerably reduced and the number of drilling strokes was nearly doubled. Combining improved pressing behavior with proper doping and optimized processing new applications of submicron and ultrafine hardmetals could be obtained by using complex shaped metal cutting inserts. Apart from these application examples the paper gives some insight into fundamental investigations an sintering and properties of ultrafine hardmetals and shows in particular the influence of milling, doping and sintering an the properties of ultrafine hardmetals. The paper also presents a new ultrafine WC grade showing a 0.1 μm WC intercept of a sintered WC - 10 wt % Co structure and a hardness of HV 30 = 2050 for a 1 wt % mixed VC/Cr 3 C 2 doping. (author)

  5. Novel Ultrafine Fibrous Poly(tetrafluoroethylene Hollow Fiber Membrane Fabricated by Electrospinning

    Directory of Open Access Journals (Sweden)

    Qinglin Huang

    2018-04-01

    Full Text Available Novel poly(tetrafluoroethylene (PTFE hollow fiber membranes were successfully fabricated by electrospinning, with ultrafine fibrous PTFE membranes as separation layers, while a porous glassfiber braided tube served as the supporting matrix. During this process, PTFE/poly(vinylalcohol (PVA ultrafine fibrous membranes were electrospun while covering the porous glassfiber braided tube; then, the nascent PTFE/PVA hollow fiber membrane was obtained. In the following sintering process, the spinning carrier PVA decomposed; meanwhile, the ultrafine fibrous PTFE membrane shrank inward so as to further integrate with the supporting matrix. Therefore, the ultrafine fibrous PTFE membranes had excellent interface bonding strength with the supporting matrix. Moreover, the obtained ultrafine fibrous PTFE hollow fiber membrane exhibited superior performances in terms of strong hydrophobicity (CA > 140°, high porosity (>70%, and sharp pore size distribution. The comprehensive properties indicated that the ultrafine fibrous PTFE hollow fiber membranes could have potentially useful applications in membrane contactors (MC, especially membrane distillation (MD in harsh water environments.

  6. An Implantable CMOS Amplifier for Nerve Signals

    DEFF Research Database (Denmark)

    Nielsen, Jannik Hammel; Lehmann, Torsten

    2003-01-01

    In this paper, a low noise high gain CMOS amplifier for minute nerve signals is presented. The amplifier is constructed in a fully differential topology to maximize noise rejection. By using a mixture of weak- and strong inversion transistors, optimal noise suppression in the amplifier is achieved....... A continuous-time current-steering offset-compensation technique is utilized in order to minimize the noise contribution and to minimize dynamic impact on the amplifier input nodes. The method for signal recovery from noisy nerve signals is presented. A prototype amplifier is realized in a standard digital 0...

  7. Semiconductor quantum-dot lasers and amplifiers

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher; Borri, Paola; Ledentsov, N. N.

    2002-01-01

    -power surface emitting VCSELs. We investigated the ultrafast dynamics of quantum-dot semiconductor optical amplifiers. The dephasing time at room temperature of the ground-state transition in semiconductor quantum dots is around 250 fs in an unbiased amplifier, decreasing to below 50 fs when the amplifier...... is biased to positive net gain. We have further measured gain recovery times in quantum dot amplifiers that are significantly lower than in bulk and quantum-well semiconductor optical amplifiers. This is promising for future demonstration of quantum dot devices with high modulation bandwidth...

  8. CMOS Current-mode Operational Amplifier

    OpenAIRE

    Kaulberg, Thomas

    1992-01-01

    A fully differential-input differential-output current-mode operational amplifier (COA) is described. The amplifier utilizes three second generation current-conveyors (CCII) as the basic building blocks. It can be configured to provide either a constant gain-bandwidth product in a fully balanced current-mode feedback amplifier or a constant bandwidth in a transimpedance feedback amplifier. The amplifier is found to have a gain bandwidth product of 8 MHz, an offset current of 0.8 ¿A (signal-r...

  9. NIF/LMJ prototype amplifier mechanical design

    International Nuclear Information System (INIS)

    Horvath, J.

    1996-10-01

    Amplifier prototypes for the National Ignition Facility and the Laser Megajoule will be tested at Lawrence Livermore National Laboratory. The prototype amplifier, which is an ensemble of modules from LLNL and Centre d'Etudes de Limeil-Valenton, is cassette-based with bottom access for maintenance. A sealed maintenance transfer vehicle which moves optical cassettes between the amplifier and the assembly cleanroom, and a vacuum gripper which holds laser slabs during cassette assembly will also be tested. The prototype amplifier will be used to verify amplifier optical performance, thermal recovery time, and cleanliness of mechanical operations

  10. HIGH AVERAGE POWER OPTICAL FEL AMPLIFIERS

    International Nuclear Information System (INIS)

    2005-01-01

    Historically, the first demonstration of the optical FEL was in an amplifier configuration at Stanford University [l]. There were other notable instances of amplifying a seed laser, such as the LLNL PALADIN amplifier [2] and the BNL ATF High-Gain Harmonic Generation FEL [3]. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance FEL's with average power of 100 kW or more. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting Energy Recovery Linacs (ERL) combine well with the high-gain FEL amplifier to produce unprecedented average power FELs. This combination has a number of advantages. In particular, we show that for a given FEL power, an FEL amplifier can introduce lower energy spread in the beam as compared to a traditional oscillator. This properly gives the ERL based FEL amplifier a great wall-plug to optical power efficiency advantage. The optics for an amplifier is simple and compact. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Linac which is under construction at Brookhaven National Laboratory's Collider-Accelerator Department

  11. Audio power amplifier design handbook

    CERN Document Server

    Self, Douglas

    2013-01-01

    This book is essential for audio power amplifier designers and engineers for one simple reason...it enables you as a professional to develop reliable, high-performance circuits. The Author Douglas Self covers the major issues of distortion and linearity, power supplies, overload, DC-protection and reactive loading. He also tackles unusual forms of compensation and distortion produced by capacitors and fuses. This completely updated fifth edition includes four NEW chapters including one on The XD Principle, invented by the author, and used by Cambridge Audio. Cro

  12. Cathode-follower power amplifier

    International Nuclear Information System (INIS)

    Giordano, S.; Puglisi, M.

    1983-01-01

    In circular accelerators and particularly in storage rings it is essential that the total impedance, as seen by the beam, be kept below some critical value. A model of the accelerating system was built using a single-ended cathode-follower amplifier driving a ferrite-loaded cavity. The system operated at 234.5 kHz with a peak output voltage of +-10 kV on the gap. The dynamic output impedance, as measured on the gap, was < 15 ohms

  13. Fabrication and characterization of dual-functional ultrafine composite fibers with phase-change energy storage and luminescence properties.

    Science.gov (United States)

    Xi, Peng; Zhao, Tianxiang; Xia, Lei; Shu, Dengkun; Ma, Menjiao; Cheng, Bowen

    2017-01-09

    Ultrafine composite fibers consisting of a thermoplastic polyurethane solid-solid phase-change material and organic lanthanide luminescent materials were prepared through a parallel electrospinning technique as an innovative type of ultrafine, dual-functional fibers containing phase-change and luminescent properties. The morphology and structure, thermal energy storage, and luminescent properties of parallel electrospun ultrafine fibers were investigated. Scanning electron microscopy (SEM) images showed that the parallel electrospun ultrafine fibers possessed the desired morphologies with smaller average fiber diameters than those of traditional mixed electrospun ultrafine fibers. Transmission electron microscopy (TEM) images revealed that the parallel electrospun ultrafine fibers were composed of two parts. Polymeric phase-change materials, which can be directly produced and spun, were used to provide temperature stability, while a mixture of polymethyl methacrylate and an organic lanthanide complex acted as the luminescent unit. Differential scanning calorimetry (DSC) and luminescence measurements indicated that the unique structure of the parallel electrospun ultrafine fibers provides the products with good thermal energy storage and luminescence properties. The fluorescence intensity and the phase-change enthalpy values of the ultrafine fibers prepared by parallel electrospinning were respectively 1.6 and 2.1 times those of ultrafine fibers prepared by mixed electrospinning.

  14. Understanding the synergistic effect and the main factors influencing the enzymatic hydrolyzability of corn stover at low enzyme loading by hydrothermal and/or ultrafine grinding pretreatment.

    Science.gov (United States)

    Zhang, Haiyan; Li, Junbao; Huang, Guangqun; Yang, Zengling; Han, Lujia

    2018-05-26

    A thorough assessment of the microstructural changes and synergistic effects of hydrothermal and/or ultrafine grinding pretreatment on the subsequent enzymatic hydrolysis of corn stover was performed in this study. The mechanism of pretreatment was elucidated by characterizing the particle size, specific surface area (SSA), pore volume (PV), average pore size, cellulose crystallinity (CrI) and surface morphology of the pretreated samples. In addition, the underlying relationships between the structural parameters and final glucose yields were elucidated, and the relative significance of the factors influencing enzymatic hydrolyzability were assessed by principal component analysis (PCA). Hydrothermal pretreatment at a lower temperature (170 °C) combined with ultrafine grinding achieved a high glucose yield (80.36%) at a low enzyme loading (5 filter paper unit (FPU)/g substrate) which is favorable. The relative significance of structural parameters in enzymatic hydrolyzability was SSA > PV > average pore size > CrI/cellulose > particle size. PV and SSA exhibited logarithmic correlations with the final enzymatic hydrolysis yield. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Pump-induced optical distortions in disk amplifier modules: holographic and interferometric measurements

    International Nuclear Information System (INIS)

    Linford, G.J.; Chau, H.H.; Glaze, J.A.; Layne, C.B.; Rainer, F.

    1975-01-01

    Interferometric measurements have been made of the optical distortions induced in laser disk amplifiers during the flashlamp pumping pulse. Both conventional interferometric methods and the techniques of double exposure holographic interferometry were used to identify four major sources of pump-induced optical distortions: subsonic intrusion of hot gas (traced to leakage of atmospheric oxygen into the amplifier), microexplosions of dust particles, thermally induced optical distortions in the glass disks, and gaseous optical distortion effects caused by turbulent flow of the purging nitrogen gas supply used within the laser amplifier head. Methods for reducing or eliminating the effects of each of these optical distortions are described

  16. Radiosynthesis and in vitro evaluation of the polystyrene particles as a promising probe in biomedical sciences

    International Nuclear Information System (INIS)

    Chen Jianmin; Tan Mingguang; Wu Yuanfang; Zhang Guilin; Li Yan

    2005-01-01

    Polystyrene particles with precise monodisperse particle size distributions ranging from 20nm to 90μm is now commercially available and it has very useful and versatile applications in many life sciences research fields. A simple direct labeling method was used to synthesis the iodinated ultrafine polystyrene particles. The assay of X-ray photoelectron spectroscopy(XPS) as well as Fourier Transform Infrared Spectroscopy (FTIR) indicated the formation of stable covalent bond to aryl group of the polymer particles. The purified radiosynthesis product was incubated with serum of rat, and then evaluated by in vitro stability test. The result showed that radioiodinated ultrafine polystyrene particles were largely unmetablized at 2 hours post-exposure, indicating the potential useful application of this widely used polymer particles as a promising probe in biomedical and pharmaceutical sciences.

  17. On spin-canting in maghemite particles

    DEFF Research Database (Denmark)

    Linderoth, Søren; Hendriksen, Peter Vang; Bødker, F.

    1994-01-01

    The degree of alignment of the magnetic moments of Fe3+ ions in ultrafine maghemite particles has been studied in samples with induced magnetic texture. The textured samples were prepared by freezing ferrofluids, containing 7.5 nm maghemite particles, in a magnetic field. Mössbauer spectroscopy...... studies of the textured samples in large magnetic fields demonstrate that the lack of full alignment is not an effect of large magnetic anisotropy, as suggested recently, but that the effect is rather due to canting of individual spins. Journal of Applied Physics is copyrighted by The American Institute...

  18. The Particle Number Emission Characteristics of the Diesel Engine with a Catalytic Diesel Particle Filter

    Directory of Open Access Journals (Sweden)

    Li Jia Qiang

    2016-01-01

    Full Text Available Due to their adverse health effects and their abundance in urban areas, diesel exhaust ultrafine particles caused by the aftertreatment devices have been of great concern in the past years. An experiment of particles number emissions was carried out on a high-pressure, common rail diesel engine with catalytic diesel particle filter (CDPF to investigate the impact of CDPF on the number emission characteristics of particles. The results indicated that the conversion rates of CDPF is over 97%. The size distributions of particles are bimodal lognormal distributions downstream CDPF at 1400 r/min and 2300 r/min. CDPF has a lower conversion rates on the nucleation mode particles. The geometric number mean diameters of particles downstream CDPF is smaller than that upstream CDPF.

  19. Sources of sub-micrometre particles near a major international airport

    Science.gov (United States)

    Masiol, Mauro; Harrison, Roy M.; Vu, Tuan V.; Beddows, David C. S.

    2017-10-01

    The international airport of Heathrow is a major source of nitrogen oxides, but its contribution to the levels of sub-micrometre particles is unknown and is the objective of this study. Two sampling campaigns were carried out during warm and cold seasons at a site close to the airfield (1.2 km). Size spectra were largely dominated by ultrafine particles: nucleation particles ( strategies are applied successfully.

  20. Mode control in a high-gain relativistic klystron amplifier

    Science.gov (United States)

    Li, Zheng-Hong; Zhang, Hong; Ju, Bing-Quan; Su, Chang; Wu, Yang

    2010-05-01

    Middle cavities between the input and output cavity can be used to decrease the required input RF power for the relativistic klystron amplifier. Meanwhile higher modes, which affect the working mode, are also easy to excite in a device with more middle cavities. In order for the positive feedback process for higher modes to be excited, a special measure is taken to increase the threshold current for such modes. Higher modes' excitation will be avoided when the threshold current is significantly larger than the beam current. So a high-gain S-band relativistic klystron amplifier is designed for the beam of current 5 kA and beam voltage 600 kV. Particle in cell simulations show that the gain is 1.6 × 105 with the input RF power of 6.8 kW, and that the output RF power reaches 1.1 GW.

  1. Development of amplifier and shaper for high-rate MWPC

    International Nuclear Information System (INIS)

    Kamiji, Ichinori; Nanjo, Hajime; Kawasaki, Naoki; Maeda, Yosuke; Naito, Daichi; Seki, Shigeto; Nakagiri, Kota; Sasao, Noboru; Nomura, Tadashi

    2015-01-01

    A multi-wire proportional chamber (MWPC) will be used as an in-beam charged particle detector for the J-PARC E14 (KOTO) experiment. The maximum counting rate of the MWPC is expected to be up to 1 MHz per channel due to the high neutron and photon flux, expected to be 1 GHz for the 30 x 30 cm"2 area. An amplifier to cope with such high counting-rate is required. We developed a prototype of such amplifier, which has a charge preamplifier with the integration time of 3 ns and a pulse shaping part with three pole-zero cancellation networks. The shaper reduced the characteristic long tail lasting tens of microseconds in the signal of MWPC to 150 ns. Its performance has been tested by using a single-channel MWPC which has almost the same geometrical parameters as the MWPC to be installed in the KOTO experiment. (author)

  2. A system for biasing a differential amplifier

    International Nuclear Information System (INIS)

    Barbier, Daniel; Ittel, J.M.; Poujois, Robert

    1975-01-01

    This invention concerns a system for biasing a differential amplifier. It particularly applies to the integrated differential amplifiers designed with MOS field effect transistors. Variations in the technological parameters may well cause the amplifying transistors to work outside their usual operational area, in other words outside the linear part of the transfer characteristic. To ensure that these transistors function correctly, it is necessary that the value of the voltage difference at the output be equally null. To do this and to centre on the so called 'rest' point of the amplifier transfer charateristic, the condition will be set that the output potentials of each amplifier transistor should have a zero value or a constant value as sum. With this in view, the bias on the source (generally a transistor powered by its grid bias voltage) supplying current to the two amplifying transistors fitted in parallel, is permanently adjusted in a suitable manner [fr

  3. Gold Nanoparticle Labels Amplify Ellipsometric Signals

    Science.gov (United States)

    Venkatasubbarao, Srivatsa

    2008-01-01

    The ellipsometric method reported in the immediately preceding article was developed in conjunction with a method of using gold nanoparticles as labels on biomolecules that one seeks to detect. The purpose of the labeling is to exploit the optical properties of the gold nanoparticles in order to amplify the measurable ellipsometric effects and thereby to enable ultrasensitive detection of the labeled biomolecules without need to develop more-complex ellipsometric instrumentation. The colorimetric, polarization, light-scattering, and other optical properties of nanoparticles depend on their sizes and shapes. In the present method, these size-and-shape-dependent properties are used to magnify the polarization of scattered light and the diattenuation and retardance of signals derived from ellipsometry. The size-and-shape-dependent optical properties of the nanoparticles make it possible to interrogate the nanoparticles by use of light of various wavelengths, as appropriate, to optimally detect particles of a specific type at high sensitivity. Hence, by incorporating gold nanoparticles bound to biomolecules as primary or secondary labels, the performance of ellipsometry as a means of detecting the biomolecules can be improved. The use of gold nanoparticles as labels in ellipsometry has been found to afford sensitivity that equals or exceeds the sensitivity achieved by use of fluorescence-based methods. Potential applications for ellipsometric detection of gold nanoparticle-labeled biomolecules include monitoring molecules of interest in biological samples, in-vitro diagnostics, process monitoring, general environmental monitoring, and detection of biohazards.

  4. Enhanced Gain in Photonic Crystal Amplifiers

    DEFF Research Database (Denmark)

    Ek, Sara; Semenova, Elizaveta; Hansen, Per Lunnemann

    2012-01-01

    We experimentally demonstrate enhanced gain in the slow-light regime of quantum well photonic crystal amplifiers. A strong gain enhancement is observed with the increase of the group refractive index, due to light slow-down. The slow light enhancement is shown in a amplified spontaneous emission....... These results are promising for short and efficient semiconductor optical amplifiers. This effect will also benefit other devices, such as mode locked lasers....

  5. Very broad bandwidth klystron amplifiers

    Science.gov (United States)

    Faillon, G.; Egloff, G.; Farvet, C.

    Large surveillance radars use transmitters at peak power levels of around one MW and average levels of a few kW, and possibly several tens of kW, in S band, or even C band. In general, the amplification stage of these transmitters is a microwave power tube, frequently a klystron. Although designers often turn to klystrons because of their good peak and average power capabilities, they still see them as narrow band amplifiers, undoubtedly because of their resonant cavities which, at first sight, would seem highly selective. But, with the progress of recent years, it has now become quite feasible to use these tubes in installations requiring bandwidths in excess of 10 - 12 percent, and even 15 percent, at 1 MW peak for example, in S-band.

  6. Hydraulically amplified PZT mems actuator

    Science.gov (United States)

    Miles, Robin R.

    2004-11-02

    A hydraulically amplified microelectromechanical systems actuator. A piece of piezoelectric material or stacked piezo bimorph is bonded or deposited as a thin film. The piece is operatively connected to a primary membrane. A reservoir is operatively connected to the primary membrane. The reservoir contains a fluid. A membrane is operatively connected to the reservoir. In operation, energizing the piezoelectric material causing the piezoelectric material to bow. Bowing of the piezoelectric material causes movement of the primary membrane. Movement of the primary membrane results in a force in being transmitted to the liquid in the reservoir. The force in the liquid causes movement of the membrane. Movement of the membrane results in an operating actuator.

  7. Transverse pumped laser amplifier architecture

    Science.gov (United States)

    Bayramian, Andrew James; Manes, Kenneth; Deri, Robert; Erlandson, Al; Caird, John; Spaeth, Mary

    2013-07-09

    An optical gain architecture includes a pump source and a pump aperture. The architecture also includes a gain region including a gain element operable to amplify light at a laser wavelength. The gain region is characterized by a first side intersecting an optical path, a second side opposing the first side, a third side adjacent the first and second sides, and a fourth side opposing the third side. The architecture further includes a dichroic section disposed between the pump aperture and the first side of the gain region. The dichroic section is characterized by low reflectance at a pump wavelength and high reflectance at the laser wavelength. The architecture additionally includes a first cladding section proximate to the third side of the gain region and a second cladding section proximate to the fourth side of the gain region.

  8. Design of an 1800nm Raman amplifier

    DEFF Research Database (Denmark)

    Svane, Ask Sebastian; Rottwitt, Karsten

    2013-01-01

    We present the experimental results for a Raman amplifier that operates at 1810 nm and is pumped by a Raman fiber laser at 1680 nm. Both the pump laser and the Raman amplifier is polarization maintaining. A challenge when scaling Raman amplifiers to longer wavelengths is the increase...... in transmission loss, but also the reduction in the Raman gain coefficient as the amplifier wavelength is increased. Both polarization components of the Raman gain is characterized, initially for linearly co-polarized signal and pump, subsequently linearly polarized orthogonal signal and pump. The noise...

  9. Reflection amplifiers in self-regulated learning

    NARCIS (Netherlands)

    Verpoorten, Dominique

    2012-01-01

    Verpoorten, D. (2012). Reflection amplifiers in self-regulated learning. Doctoral thesis. November, 9, 2012, Heerlen, The Netherlands: Open Universiteit (CELSTEC). Datawyse / Universitaire Pers Maastricht.

  10. Fabrication of ultra-fine nanostructures using edge transfer printing.

    Science.gov (United States)

    Xue, Mianqi; Li, Fengwang; Cao, Tingbing

    2012-03-21

    The exploration of new methods and techniques for application in diverse fields, such as photonics, microfluidics, biotechnology and flexible electronics is of increasing scientific and technical interest for multiple uses over distance of 10-100 nm. This article discusses edge transfer printing--a series of unconventional methods derived from soft lithography for nanofabrication. It possesses the advantages of easy fabrication, low-cost and great serviceability. In this paper, we show how to produce exposed edges and use various materials for edge transfer printing, while nanoskiving, nanotransfer edge printing and tunable cracking for nanogaps are introduced. Besides this, different functional materials, such as metals, inorganic semiconductors and polymers, as well as localised heating and charge patterning, are described here as unconventional "inks" for printing. Edge transfer printing, which can effectively produce sub-100 nm scale ultra-fine structures, has broad applications, including metallic nanowires as nanoelectrodes, semiconductor nanowires for chemical sensors, heterostructures of organic semiconductors, plasmonic devices and so forth. This journal is © The Royal Society of Chemistry 2012

  11. Magnetic anisotropy of ultrafine 316L stainless steel fibers

    Energy Technology Data Exchange (ETDEWEB)

    Shyr, Tien-Wei, E-mail: twshyr@fcu.edu.tw [Department of Fiber and Composite Materials, Feng Chia University, No. 100, Wenhwa Road, Seatwen, Taichung 40724, Taiwan, ROC (China); Huang, Shih-Ju [Department of Fiber and Composite Materials, Feng Chia University, No. 100, Wenhwa Road, Seatwen, Taichung 40724, Taiwan, ROC (China); Wur, Ching-Shuei [Department of Physics, National Cheng Kung University, No. 1, University Road, Tainan 70101, Taiwan, ROC (China)

    2016-12-01

    An as-received 316L stainless steel fiber with a diameter of 20 μm was drawn using a bundle drawing process at room temperature to form ultrafine stainless steel fibers with diameters of 12, 8, and 6 μm. The crystalline phases of the fibers were analyzed using the X-ray diffraction (XRD) profile fitting technique. The grain sizes of γ-austenite and α′-martensite were reduced to nanoscale sizes after the drawing process. XRD analysis and focused ion beam-scanning electron microscope observations showed that the newly formed α′-martensitic grains were closely arrayed in the drawing direction. The magnetic property was measured using a superconducting quantum interference device vibrating sample magnetometer. The magnetic anisotropy of the fibers was observed by applying a magnetic field parallel and perpendicular to the fiber axis. The results showed that the microstructure anisotropy including the shape anisotropy, magnetocrystalline anisotropy, and the orientation of the crystalline phases strongly contributed to the magnetic anisotropy. - Highlights: • The martensitic transformation of the 316L SS fiber occurred during the cold drawn. • The grain sizes of γ-austenite and α′-martensite were reduced to the nanoscale. • The newly formed martensitic grains were closely arrayed in the drawing direction. • The drawing process caused the magnetic easy axis to be aligned with the fiber axis. • The microstructure anisotropy strongly contributed to the magnetic anisotropy.

  12. Potential of ultrafine grained materials as high performance penetrator materials

    Directory of Open Access Journals (Sweden)

    Lee C.S.

    2012-08-01

    Full Text Available The shear formability and the metal jet formability are important for the kinetic energy penetrator and the chemical energy penetrator, respectively. The shear formability of ultrafine grained (UFG steel was examined, mainly focusing on the effects of the grain shape on the shear characteristics. For this purpose, UFG 4130 steel having the different UFG structures, the lamellar UFG and the equiaxed UFG, was prepared by equal channel angular pressing (ECAP. The lamellar UFG steel exhibited more sharper and localized shear band formation than the equiaxed UFG steel. This is because a lamellar UFG structure was unfavourable against grain rotation which is a main mechanism of the band propagation in UFG materials. Meanwhile, the metal jet formability of UFG OFHC Cu also processed by ECAP was compared to that of coarse grained (CG one by means of dynamic tensile extrusion (DTE tests. CG OFHC Cu exhibited the higher DTE ductility, i.e. better metal jet stability, than UFG OFHC Cu. The initial high strength and the lack of strain hardenability of UFG OFHC Cu were harmful to the metal jet formability.

  13. Bake hardening of ultra-fine grained low carbon steel produced by constrained groove pressing

    International Nuclear Information System (INIS)

    Alihosseini, H.; Dehghani, K.

    2012-01-01

    Highlights: ► BH of UFG low carbon steel sheets was studied. ► Three passes of CGP are used for producing of UFG sheets. ► Maximum BH was achieved to the UFG specimen pre-strained 8% by baking at 250 °C. - Abstract: In the present work, the bake hardening of ultra-fine grained low carbon steel was compared with that of its coarse-grain counterpart. The ultra-fine grained sheets were produced by applying three passes of constrained groove pressing resulting the grains of 260–270 nm. The microstructure of ultra-fine grain specimens were characterized using electron back-scatter diffraction technique. Then, the bake hardenability of ultra-fine grain and coarse-grain samples were compared by pre-straining to 4, 6 and 8% followed by baking at 150 °C and 250 °C for 20 min. The results show that in case of baking at 250 °C, there was an increase about 108%, 93%, and 72% in the bake hardening for 4%, 6% and 8% pre-strain, respectively. As for baking at 150 °C, these values were 170%, 168%, and 100%, respectively for 4%, 6% and 8% pre-strain. The maximum in bake hardenability (103 MPa) and final yield stress (563 MPa) were pertaining to the ultra-fine grain specimen pre-strained 8% followed by baking at 250 °C.

  14. Fatigue and creep–fatigue deformation of an ultra-fine precipitate strengthened advanced austenitic alloy

    International Nuclear Information System (INIS)

    Carroll, M.C.; Carroll, L.J.

    2012-01-01

    An advanced austenitic alloy, HT-UPS (high-temperature ultrafine-precipitation-strengthened), has been identified as an ideal candidate material for the structural components of fast reactors and energy-conversion systems. HT-UPS alloys demonstrate improved creep resistance relative to 316 stainless steel (SS) through additions of Ti and Nb, which precipitate to form a widespread dispersion of stable nanoscale metallic carbide (MC) particles in the austenitic matrix. To investigate the behavior in more representative conditions than are offered by uniaxial creep tests, the low-cycle continuous fatigue and combined creep–fatigue response of an HT-UPS alloy have been investigated at 650 °C and 1.0% total strain, with an R-ratio of −1 and hold times at peak tensile strain of up to 150 min. The cyclic deformation response of HT-UPS is directly compared to that of standard 316 SS. The measured values for total cycles to failure between the two alloys are similar, despite differences in peak stress profiles and in qualitative observations of the deformed microstructures. Crack propagation is primarily transgranular in both fatigue and creep–fatigue of each alloy at the investigated conditions. Internal grain boundary damage in the form of fine cracks resulting from the tensile hold is present following the application of hold times of 60 min and longer, and considerably more internal cracks are quantifiable in 316 SS than in HT-UPS. The dislocation substructures observed in the deformed material differ substantially; an equiaxed cellular structure is observed in the microstructure of 316 SS, whereas HT-UPS exhibits widespread and relatively homogenous tangles of dislocations pinned by the nanoscale MC precipitates. The significant effect of the fine distribution of precipitates on observed fatigue and creep–fatigue response is described in three distinct behavioral regions as the microstructure evolves with continued cycling.

  15. Fatigue and creep-fatigue deformation of an ultra-fine precipitate strengthened advanced austenitic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, M.C., E-mail: Mark.Carroll@INL.gov [Idaho National Laboratory, 1955 Fremont, PO Box 1625, Idaho Falls, ID 83415-2218 (United States); Carroll, L.J. [Idaho National Laboratory, 1955 Fremont, PO Box 1625, Idaho Falls, ID 83415-2218 (United States)

    2012-10-30

    An advanced austenitic alloy, HT-UPS (high-temperature ultrafine-precipitation-strengthened), has been identified as an ideal candidate material for the structural components of fast reactors and energy-conversion systems. HT-UPS alloys demonstrate improved creep resistance relative to 316 stainless steel (SS) through additions of Ti and Nb, which precipitate to form a widespread dispersion of stable nanoscale metallic carbide (MC) particles in the austenitic matrix. To investigate the behavior in more representative conditions than are offered by uniaxial creep tests, the low-cycle continuous fatigue and combined creep-fatigue response of an HT-UPS alloy have been investigated at 650 Degree-Sign C and 1.0% total strain, with an R-ratio of -1 and hold times at peak tensile strain of up to 150 min. The cyclic deformation response of HT-UPS is directly compared to that of standard 316 SS. The measured values for total cycles to failure between the two alloys are similar, despite differences in peak stress profiles and in qualitative observations of the deformed microstructures. Crack propagation is primarily transgranular in both fatigue and creep-fatigue of each alloy at the investigated conditions. Internal grain boundary damage in the form of fine cracks resulting from the tensile hold is present following the application of hold times of 60 min and longer, and considerably more internal cracks are quantifiable in 316 SS than in HT-UPS. The dislocation substructures observed in the deformed material differ substantially; an equiaxed cellular structure is observed in the microstructure of 316 SS, whereas HT-UPS exhibits widespread and relatively homogenous tangles of dislocations pinned by the nanoscale MC precipitates. The significant effect of the fine distribution of precipitates on observed fatigue and creep-fatigue response is described in three distinct behavioral regions as the microstructure evolves with continued cycling.

  16. Electrodeposited ultrafine TaOx/CB catalysts for PEFC cathode application: Their oxygen reduction reaction kinetics

    KAUST Repository

    Seo, Jeongsuk

    2014-12-01

    Ultrafine TaOx nanoparticles were electrodeposited on carbon black (CB) powder in a nonaqueous Ta complex solution at room temperature, and the resultant TaOx/CB catalysts were assessed as oxygen reduction reaction (ORR) electrocatalysts for polymer electrolyte fuel cell (PEFC) cathodes. The Ta electrodeposition process was scaled up using a newly designed working electrode containing a CB dense layer, without introducing any binder such as the ionomer Nafion in the electrode for electrodeposition. The electrodeposited TaOx/CB powders were removed from the deposition electrode and subsequent H2 treatment at varying temperatures between 523 and 1073 K was attempted to increase the ORR performance. The TaOx/CB samples were characterized by SEM, STEM, XPS, and EELS measurements. XPS and EELS results indicated the reduced nature of the Ta species caused by the high-temperature treatment in H2, while STEM images clearly revealed that the TaOx particles aggregated as the treatment temperature increased. When the TaOx/CB catalyst, which was treated at 873 K for 2 h, was deposited on a glassy carbon substrate with Nafion ionomer, it resulted in the highest activity among the samples investigated, giving an onset potential of 0.95 VRHE at -2 μA cm-2 in a 0.1 M H2SO4 solution. Moreover, the long-term stability test with 10,000 cycles of the voltammetry only led to a 6% loss in the ORR currents, demonstrating the high stability of the TaOx/CB catalysts. Kinetic analysis by R(R)DE indicated that the four-electron transfer pathway in the ORR process was dominant for this TaOx/CB catalyst, and Tafel plots showed a slope corresponding to a one-electron reaction for the rate-determining step.

  17. Electrodeposited ultrafine TaOx/CB catalysts for PEFC cathode application: Their oxygen reduction reaction kinetics

    KAUST Repository

    Seo, Jeongsuk; Anjum, Dalaver H.; Takanabe, Kazuhiro; Kubota, Jun; Domen, Kazunari

    2014-01-01

    Ultrafine TaOx nanoparticles were electrodeposited on carbon black (CB) powder in a nonaqueous Ta complex solution at room temperature, and the resultant TaOx/CB catalysts were assessed as oxygen reduction reaction (ORR) electrocatalysts for polymer electrolyte fuel cell (PEFC) cathodes. The Ta electrodeposition process was scaled up using a newly designed working electrode containing a CB dense layer, without introducing any binder such as the ionomer Nafion in the electrode for electrodeposition. The electrodeposited TaOx/CB powders were removed from the deposition electrode and subsequent H2 treatment at varying temperatures between 523 and 1073 K was attempted to increase the ORR performance. The TaOx/CB samples were characterized by SEM, STEM, XPS, and EELS measurements. XPS and EELS results indicated the reduced nature of the Ta species caused by the high-temperature treatment in H2, while STEM images clearly revealed that the TaOx particles aggregated as the treatment temperature increased. When the TaOx/CB catalyst, which was treated at 873 K for 2 h, was deposited on a glassy carbon substrate with Nafion ionomer, it resulted in the highest activity among the samples investigated, giving an onset potential of 0.95 VRHE at -2 μA cm-2 in a 0.1 M H2SO4 solution. Moreover, the long-term stability test with 10,000 cycles of the voltammetry only led to a 6% loss in the ORR currents, demonstrating the high stability of the TaOx/CB catalysts. Kinetic analysis by R(R)DE indicated that the four-electron transfer pathway in the ORR process was dominant for this TaOx/CB catalyst, and Tafel plots showed a slope corresponding to a one-electron reaction for the rate-determining step.

  18. Particle size distribution of mainstream tobacco and marijuana smoke. Analysis using the electrical aerosol analyzer.

    Science.gov (United States)

    Anderson, P J; Wilson, J D; Hiller, F C

    1989-07-01

    Accurate measurement of cigarette smoke particle size distribution is important for estimation of lung deposition. Most prior investigators have reported a mass median diameter (MMD) in the size range of 0.3 to 0.5 micron, with a small geometric standard deviation (GSD), indicating few ultrafine (less than 0.1 micron) particles. A few studies, however, have suggested the presence of ultrafine particles by reporting a smaller count median diameter (CMD). Part of this disparity may be due tot he inefficiency to previous sizing methods in measuring ultrafine size range, to evaluate size distribution of smoke from standard research cigarettes, commercial filter cigarettes, and from marijuana cigarettes with different delta 9-tetrahydrocannabinol contents. Four 35-cm3, 2-s puffs were generated at 60-s intervals, rapidly diluted, and passed through a charge neutralizer and into a 240-L chamber. Size distribution for six cigarettes of each type was measured, CMD and GSD were determined from a computer-generated log probability plot, and MMD was calculated. The size distribution parameters obtained were similar for all cigarettes tested, with an average CMD of 0.1 micron, a MMD of 0.38 micron, and a GSD of 2.0. The MMD found using the EAA is similar to that previously reported, but the CMD is distinctly smaller and the GSD larger, indicating the presence of many more ultrafine particles. These results may explain the disparity of CMD values found in existing data. Ultrafine particles are of toxicologic importance because their respiratory tract deposition is significantly higher than for particles 0.3 to 0.5 micron and because their large surface area facilitates adsorption and delivery of potentially toxic gases to the lung.

  19. Distributed feedback laser amplifiers combining the functions of amplifiers and channel filters

    DEFF Research Database (Denmark)

    Wang, Z.; Durhuus, T.; Mikkelsen, Benny

    1994-01-01

    A dynamic model for distributed feedback amplifiers, including the mode coupled equations and the carrier rate equation, is established. The presented mode coupled equations have taken into account the interaction between fast changing optical signal and the waveguide with corrugations. By showin...... the possibility of amplifying 100 ps pulses without pulse broadening, we anticipate that a distributed feedback amplifier can be used as a combined amplifier and channel filter in high bit rate transmission systems....

  20. Chevrel phases superconductive and ultrafine powders synthesis and characterization; Synthese et caracterisation de poudres ultrafines supraconductrices de phases de Chevrel

    Energy Technology Data Exchange (ETDEWEB)

    Even-Boudjada, S

    1994-12-01

    This work deals with the Chevrel phases superconductive and ultrafine powders synthesis and characterization. The first part of this study presents some new way of synthesis (precipitation, coprecipitation) of Chevrel phases precursors powders (PbS, SnS, MoS{sub 2}) and their characterizations (X-ray fluorescence analysis, ICP mass spectroscopy, scanning electron microscopy, transmission electron microscopy and laser granulometry). These new synthesis methods lead to quasi spherical morphology grains and very weak size grains (0.2 to 0.5 {mu}m) whereas the chemical preparation from the solid state elements gives very different morphology grains (small plates) with a size of 1 to 20 {mu}m. In the second part is shown the interest of the binary Mo{sub 6} S{sub 8} as precursor in the synthesis of ternary superconductive phases (Li, Ni, Cu, Pb). The last part presents the formation reaction of the phase PbMo{sub 6} S{sub 8} and its main chemical and physical properties. Thus some calorimetric measures associated with X-ray diffraction analysis have been realized and have allowed to understand the different reactions occurring during the PbMo{sub 6}S{sub 8} synthesis. (O.L.). 100 refs., figs., tabs.

  1. Self-pulsation in Raman fiber amplifiers

    DEFF Research Database (Denmark)

    Pedersen, Martin Erland Vestergaard; Ott, Johan Raunkjær; Rottwitt, Karsten

    2009-01-01

    Dynamic behavior caused by Brillouin scattering in Raman fiber amplifiers is studied. Modes of self-pulsation steady state oscillations are found. Their dependence on amplification scheme is demonstrated.......Dynamic behavior caused by Brillouin scattering in Raman fiber amplifiers is studied. Modes of self-pulsation steady state oscillations are found. Their dependence on amplification scheme is demonstrated....

  2. Pulse amplifier with high 'common mode rejection'

    International Nuclear Information System (INIS)

    Ijlst, P.

    1987-01-01

    The input signal of a pulse amplifier contains large 'common-mode' signals which have to be suppressed. A transformer, especially constructed for this purpose, is described. It has been tried to optimize the signal to noise ratio of the pulse amplifier by means of noise analysis. (Auth.)

  3. BROADBAND TRAVELLING WAVE SEMICONDUCTOR OPTICAL AMPLIFIER

    DEFF Research Database (Denmark)

    2010-01-01

    Broadband travelling wave semiconductor optical amplifier (100, 200, 300, 400, 800) for amplification of light, wherein the amplifier (100, 200, 300, 400, 800) comprises a waveguide region (101, 201, 301, 401, 801) for providing confinement of the light in transverse directions and adapted...

  4. Bevalac injector final stage RF amplifier upgrades

    International Nuclear Information System (INIS)

    Howard, D.; Calvert, J.; Dwinell, R.; Lax, J.; Lindner, A.; Richter, R.; Ridgeway, W.

    1991-01-01

    With the assistance of the DOE In-house Energy Management Program, the Bevalac injector final stage RF amplifier systems have been successfully upgraded to reduce energy consumption and operating costs. This recently completed project removed the energy-inefficient plate voltage modulator circuits that were used in conjunction with the final stage RF amplifiers. Construction, design, and operating parameters are described in detail

  5. Method for reducing snap in magnetic amplifiers

    Science.gov (United States)

    Fischer, R. L. E.; Word, J. L.

    1968-01-01

    Method of reducing snap in magnetic amplifiers uses a degenerative feedback circuit consisting of a resistor and a separate winding on a magnetic core. The feedback circuit extends amplifier range by allowing it to be used at lower values of output current.

  6. Effect of ultrafine grain on tensile behaviour and corrosion resistance of the duplex stainless steel.

    Science.gov (United States)

    Jinlong, Lv; Tongxiang, Liang; Chen, Wang; Limin, Dong

    2016-05-01

    The ultrafine grained 2205 duplex stainless steel was obtained by cold rolling and annealing. The tensile properties were investigated at room temperature. Comparing with coarse grained stainless steel, ultrafine grained sample showed higher strength and plasticity. In addition, grain size changed deformation orientation. The strain induced α'-martensite was observed in coarse grained 2205 duplex stainless steel with large strain. However, the grain refinement inhibited the transformation of α'-martensite;nevertheless, more deformation twins improved the strength and plasticity of ultrafine grained 2205 duplex stainless steel. In addition, the grain refinement improved corrosion resistance of the 2205 duplex stainless steel in sodium chloride solution. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. A fluidic/pneumatic interface amplifier

    Science.gov (United States)

    Limbert, D. E.; Kegel, T. M.

    The development of a low cost, reliable, linear pressure amplifier to interface Laminar Proportional Amplifiers (LPA) to pneumatic controllers is presented. The amplifier consists of an LPA input stage and an output stage consisting of a venturi in series with a bellows nozzle valve. The LPA output drives the bellows nozzle valve thereby altering the flowrate through the venturi. The pressure within the venturi throat region, which is the amplifier output, changes with the flowrate. Non-linear characteristics, due to supersonic flow within the venturi, are altered through the use of feedback to the LPA input. A computer based model, to aid in optimizing the amplifier design, is developed. This model incorporates the effects of shock waves and boundary layers within the venturi. Good correspondence between the model and an experimental prototype is shown.

  8. Amplified OTDR Systems for Multipoint Corrosion Monitoring

    Science.gov (United States)

    Nascimento, Jehan F.; Silva, Marcionilo J.; Coêlho, Isnaldo J. S.; Cipriano, Eliel; Martins-Filho, Joaquim F.

    2012-01-01

    We present two configurations of an amplified fiber-optic-based corrosion sensor using the optical time domain reflectometry (OTDR) technique as the interrogation method. The sensor system is multipoint, self-referenced, has no moving parts and can measure the corrosion rate several kilometers away from the OTDR equipment. The first OTDR monitoring system employs a remotely pumped in-line EDFA and it is used to evaluate the increase in system reach compared to a non-amplified configuration. The other amplified monitoring system uses an EDFA in booster configuration and we perform corrosion measurements and evaluations of system sensitivity to amplifier gain variations. Our experimental results obtained under controlled laboratory conditions show the advantages of the amplified system in terms of longer system reach with better spatial resolution, and also that the corrosion measurements obtained from our system are not sensitive to 3 dB gain variations. PMID:22737017

  9. An Implantable CMOS Amplifier for Nerve Signals

    DEFF Research Database (Denmark)

    Nielsen, Jannik Hammel; Lehmann, Torsten

    2001-01-01

    In this paper, a low noise high gain CMOS amplifier for minute nerve signals is presented. By using a mixture of weak- and strong inversion transistors, optimal noise suppression in the amplifier is achieved. A continuous-time offset-compensation technique is utilized in order to minimize impact...... on the amplifier input nodes. The method for signal recovery from noisy nerve signals is presented. A prototype amplifier is realized in a standard digital 0.5 μm CMOS single poly, n-well process. The prototype amplifier features a gain of 80 dB over a 3.6 kHz bandwidth, a CMRR of more than 87 dB and a PSRR...

  10. Bandwidth tunable amplifier for recording biopotential signals.

    Science.gov (United States)

    Hwang, Sungkil; Aninakwa, Kofi; Sonkusale, Sameer

    2010-01-01

    This paper presents a low noise, low power, bandwidth tunable amplifier for bio-potential signal recording applications. By employing depletion-mode pMOS transistor in diode configuration as a tunable sub pA current source to adjust the resistivity of MOS-Bipolar pseudo-resistor, the bandwidth is adjusted without any need for a separate band-pass filter stage. For high CMRR, PSRR and dynamic range, a fully differential structure is used in the design of the amplifier. The amplifier achieves a midband gain of 39.8dB with a tunable high-pass cutoff frequency ranging from 0.1Hz to 300Hz. The amplifier is fabricated in 0.18εm CMOS process and occupies 0.14mm(2) of chip area. A three electrode ECG measurement is performed using the proposed amplifier to show its feasibility for low power, compact wearable ECG monitoring application.

  11. Dual-range linearized transimpedance amplifier system

    Science.gov (United States)

    Wessendorf, Kurt O.

    2010-11-02

    A transimpedance amplifier system is disclosed which simultaneously generates a low-gain output signal and a high-gain output signal from an input current signal using a single transimpedance amplifier having two different feedback loops with different amplification factors to generate two different output voltage signals. One of the feedback loops includes a resistor, and the other feedback loop includes another resistor in series with one or more diodes. The transimpedance amplifier system includes a signal linearizer to linearize one or both of the low- and high-gain output signals by scaling and adding the two output voltage signals from the transimpedance amplifier. The signal linearizer can be formed either as an analog device using one or two summing amplifiers, or alternately can be formed as a digital device using two analog-to-digital converters and a digital signal processor (e.g. a microprocessor or a computer).

  12. Detection of Non-Amplified Genomic DNA

    CERN Document Server

    Corradini, Roberto

    2012-01-01

    This book offers a state-of-the-art overview on non amplified DNA detection methods and provides chemists, biochemists, biotechnologists and material scientists with an introduction to these methods. In fact all these fields have dedicated resources to the problem of nucleic acid detection, each contributing with their own specific methods and concepts. This book will explain the basic principles of the different non amplified DNA detection methods available, highlighting their respective advantages and limitations. The importance of non-amplified DNA sequencing technologies will be also discussed. Non-amplified DNA detection can be achieved by adopting different techniques. Such techniques have allowed the commercialization of innovative platforms for DNA detection that are expected to break into the DNA diagnostics market. The enhanced sensitivity required for the detection of non amplified genomic DNA has prompted new strategies that can achieve ultrasensitivity by combining specific materials with specifi...

  13. Anchoring ultrafine Pd nanoparticles and SnO2 nanoparticles on reduced graphene oxide for high-performance room temperature NO2 sensing.

    Science.gov (United States)

    Wang, Ziying; Zhang, Tong; Zhao, Chen; Han, Tianyi; Fei, Teng; Liu, Sen; Lu, Geyu

    2018-03-15

    In this paper, we demonstrate room-temperature NO 2 gas sensors using Pd nanoparticles (NPs) and SnO 2 NPs decorated reduced graphene oxide (Pd-SnO 2 -RGO) hybrids as sensing materials. It is found that ultrafine Pd NPs and SnO 2 NPs with particle sizes of 3-5 nm are attached to RGO nanosheets. Compared to SnO 2 -RGO hybrids, the sensor based on Pd-SnO 2 -RGO hybrids exhibited higher sensitivity at room temperature, where the response to 1 ppm NO 2 was 3.92 with the response time and recovery time being 13 s and 105 s. Moreover, such sensor exhibited excellent selectivity, and low detection limit (50 ppb). In addition to high transport capability of RGO as well as excellent NO 2 adsorption ability derived from ultrafine SnO 2 NPs and Pd NPs, the superior sensing performances of the hybrids were attributed to the synergetic effect of Pd NPs, SnO 2 NPs and RGO. Particularly, the excellent sensing performances were related to high conductivity and catalytic activity of Pd NPs. Finally, the sensing mechanism for NO 2 sensing and the reason for enhanced sensing performances by introduction of Pd NPs are also discussed. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Effect of Ultrafine Pulverization of Senecio Scandens on Growth, Immune System and Faecal Microorganisms in Piglets

    Directory of Open Access Journals (Sweden)

    J Yue1, CQ Lu1, HY Lin1, XN Wang, JQ Zheng1, JJ Chen1* and R Gooneratne2*

    2016-11-01

    Full Text Available There is increased interest in using naturally occurring compounds subjected to new technologies for enhancing pig nutrition to replace antibiotic usage in swine production. The effects of ultrafine pulverization on the size distribution, morphology of Senecio scandens Buch.-Ham., and the growth performance, serum immunity parameters and faecal microorganisms of piglets fed this powder were investigated. The size distribution and morphology of S. scandens were characterized by using a laser diffraction analyser and scanning electron microscopy respectively. Ninety Duroc×Landrace×Yorkshire piglets (average body weight of 10.43kg were randomly assigned to six treatments with three pens of five pigs per treatment. Group 1 (Control piglets were fed the basal diet only. Groups 2 to 5 were fed with the basal diet supplemented with ultrafine powder (median diameter [d0.5] of 8.89μm of S. scandens at 0.3, 0.6, 0.9, and 1.2% of the basal diet, respectively, for 30 days. For group 6, 1.2% of ordinary S. scandens powder (d0.5=88.59μm was added to the basal diet. Both S. scandens ordinary and ultrafine powder increased piglet body weight and reduced the feed to gain ratio, but the performance of piglets fed the ultrafine powder was better. In groups 4 to 6, the number of Escherechia coli in faeces and the diarrhoeal incidence were significantly lower (P<0.05 and the serum IgA, IgG, IgM contents significantly higher (P<0.05. Feeding S. scandens ultrafine powder in the diet improved piglet performance and the diet supplemented with 0.9% of the ultrafine powder was the most effective.

  15. Ultrafast disk lasers and amplifiers

    Science.gov (United States)

    Sutter, Dirk H.; Kleinbauer, Jochen; Bauer, Dominik; Wolf, Martin; Tan, Chuong; Gebs, Raphael; Budnicki, Aleksander; Wagenblast, Philipp; Weiler, Sascha

    2012-03-01

    Disk lasers with multi-kW continuous wave (CW) output power are widely used in manufacturing, primarily for cutting and welding applications, notably in the automotive industry. The ytterbium disk technology combines high power (average and/or peak power), excellent beam quality, high efficiency, and high reliability with low investment and operating costs. Fundamental mode picosecond disk lasers are well established in micro machining at high throughput and perfect precision. Following the world's first market introduction of industrial grade 50 W picosecond lasers (TruMicro 5050) at the Photonics West 2008, the second generation of the TruMicro series 5000 now provides twice the average power (100 W at 1030 nm, or 60 W frequency doubled, green output) at a significantly reduced footprint. Mode-locked disk oscillators achieve by far the highest average power of any unamplified lasers, significantly exceeding the 100 W level in laboratory set-ups. With robust long resonators their multi-microjoule pulse energies begin to compete with typical ultrafast amplifiers. In addition, significant interest in disk technology has recently come from the extreme light laser community, aiming for ultra-high peak powers of petawatts and beyond.

  16. A Kinetics Model for KrF Laser Amplifiers

    Science.gov (United States)

    Giuliani, J. L.; Kepple, P.; Lehmberg, R.; Obenschain, S. P.; Petrov, G.

    1999-11-01

    A computer kinetics code has been developed to model the temporal and spatial behavior of an e-beam pumped KrF laser amplifier. The deposition of the primary beam electrons is assumed to be spatially uniform and the energy distribution function of the nascent electron population is calculated to be near Maxwellian below 10 eV. For an initial Kr/Ar/F2 composition, the code calculates the densities of 24 species subject to over 100 reactions with 1-D spatial resolution (typically 16 zones) along the longitudinal lasing axis. Enthalpy accounting for each process is performed to partition the energy into internal, thermal, and radiative components. The electron as well as the heavy particle temperatures are followed for energy conservation and excitation rates. Transport of the lasing photons is performed along the axis on a dense subgrid using the method of characteristics. Amplified spontaneous emission is calculated using a discrete ordinates approach and includes contributions to the local intensity from the whole amplifier volume. Specular reflection off side walls and the rear mirror are included. Results of the model will be compared with data from the NRL NIKE laser and other published results.

  17. Plasma dynamic synthesis and obtaining ultrafine powders of iron oxides with high content of ε-Fe2O3

    Science.gov (United States)

    Sivkov, Alexander; Naiden, Evgenii; Ivashutenko, Alexander; Shanenkov, Ivan

    2016-05-01

    The ultrafine iron oxide powders were successfully synthesized using the plasma dynamic synthesis method, based on the use of a coaxial magnetoplasma accelerator with the iron electrode system. The synthesis was implemented in the high-speed iron-containing plasma jet, flowing into the space of the sealed chamber, filled with the gaseous mixture of oxygen and argon at different ratios. The XRD investigations showed that the synthesized products were heterophase and consisted of three main phases such as magnetite Fe3O4, hematite α-Fe2O3 and ε-Fe2O3. The SEM data confirmed the presence of three particle types: the hollow spheroids with sizes about hundreds of micrometers (magnetite), the particles with sizes up to 100 μm from the porous material of sintered submicron particles (hematite), and nanoscale particles (ε-phase). We found that at the higher oxygen concentration the content of ε-Fe2O3 is increased up to 50% at the same time with decreasing the Fe3O4 phase. The magnetic properties of the products are mainly determined by magnetite characteristics and are significantly reduced with decreasing its content in the powder. In order to investigate the synthesized ε-Fe2O3 on the ability to absorb the electromagnetic radiation in the millimeter wavelength range, we separated the product with the higher ε-phase concentration. The fraction mainly, consisting of ε-Fe2O3, showed the occurrence of the natural resonance at frequencies of 8.3 GHz and 130 GHz.

  18. Human Exposure to Dynamic Air Pollutants: Ozone in Airplanes and Ultrafine Particles in Homes

    Science.gov (United States)

    2010-01-01

    original source of my love of learning. All her grandchildren have had to tolerate, at least temporarily, being ignored while she was immersed in a book ...Indoor Air 17, 372-383. Klepeis NE, Nazaroff WW, 2006a. Modeling residential exposure to secondhand tobacco smoke. Atmospheric Environment 40, 4393...4407. Klepeis NE, Nazaroff WW, 2006b. Mitigating residential exposure to secondhand tobacco smoke. Atmospheric Environment 40, 4408-4422. 84

  19. PULMONARY EFFECTS INDUCED BY ULTRAFINE (UF) PTFE PARTICLES. (R827354C004)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  20. Surface structures and dielectric response of ultrafine BaTiO3 particles

    International Nuclear Information System (INIS)

    Jiang, B.; Peng, J.L.; Bursill, L.A.

    1998-01-01

    Characteristic differences are observed for the dielectric response and microstructures of BaTiO 3 nanoscale fine powders prepared using sol gel (SG) and steric acid gel (SAG) methods. The former exhibit a critical size below which there is no paraelectric/ferroelectric phase transition whereas BaTiO 3 prepared via the SAG route remained cubic for all conditions. Atomic resolution images of both varieties showed a high density of interesting surface steps and facets. Computer simulated images of surface structure models showed that the outer (100) surface was typically a BaO layer and that at corners and ledges the steps are typically finished with Ba+2 ions; i.e. the surfaces and steps are Ba-rich. Otherwise the surfaces were typically clean and free of amorphous layers. The relationship between the observed surfaces structures and theoretical models for size effects on the dielectric properties is discussed. (authors)

  1. Plant protein-based hydrophobic fine and ultrafine carrier particles in drug delivery systems.

    Science.gov (United States)

    Malekzad, Hedieh; Mirshekari, Hamed; Sahandi Zangabad, Parham; Moosavi Basri, S M; Baniasadi, Fazel; Sharifi Aghdam, Maryam; Karimi, Mahdi; Hamblin, Michael R

    2018-02-01

    For thousands of years, plants and their products have been used as the mainstay of medicinal therapy. In recent years, besides attempts to isolate the active ingredients of medicinal plants, other new applications of plant products, such as their use to prepare drug delivery vehicles, have been discovered. Nanobiotechnology is a branch of pharmacology that can provide new approaches for drug delivery by the preparation of biocompatible carrier nanoparticles (NPs). In this article, we review recent studies with four important plant proteins that have been used as carriers for targeted delivery of drugs and genes. Zein is a water-insoluble protein from maize; Gliadin is a 70% alcohol-soluble protein from wheat and corn; legumin is a casein-like protein from leguminous seeds such as peas; lectins are glycoproteins naturally occurring in many plants that recognize specific carbohydrate residues. NPs formed from these proteins show good biocompatibility, possess the ability to enhance solubility, and provide sustained release of drugs and reduce their toxicity and side effects. The effects of preparation methods on the size and loading capacity of these NPs are also described in this review.

  2. AIRBORNE FINE AND ULTRAFINE PARTICLES NEAR THE WORLD TRADE CENTER DISASTER SITE. (R827351)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  3. Development of a new ultrafine grained dual phase steel and examination of the effect of grain size on tensile deformation behavior

    Energy Technology Data Exchange (ETDEWEB)

    Saeidi, N., E-mail: navidsae@gmail.com; Ashrafizadeh, F.; Niroumand, B.

    2014-04-01

    Ultrafine grained dual phase (DP) steels are among the newest grades of DP steels that incorporate the uniform distribution of fine martensite particles (in the order of 1–2 μm) within a ferrite matrix. These new grades of steels have been developed in response to the world's demand for decreasing the fuel consumption in automobiles by increasing the strength to weight ratio. In the present research, a new kind of ultrafine grained DP (UFG-DP) steel with an average grain size of about 2 μm as well as a coarse grained DP (CG-DP) steel with an average grain size of about 5.4 μm was produced by consecutive intercritical annealing and cold rolling of low carbon AISI 8620 steel. The martensite volume fraction for both microstructures was the same and about 50 percent. Scanning electron microscopy (SEM) microstructural examination and room temperature tensile deformation analyses were performed on both UFG-DP and CG-DP steels and their deformation behavior in terms of strength, elongation and strain hardening was studied and compared. Room-temperature uniaxial tensile tests revealed that for a given martensite volume fraction, yield and tensile strengths were not very sensitive to martensite morphology. However, uniform and total elongation values were noticeably affected by refining martensite particles. The higher plasticity of fine martensite particles as well as the more uniform strain distribution within the UFG-DP microstructure resulted in higher strain hardenability and, finally, the higher ductility of the UFG-DP steel.

  4. Explaining the spatiotemporal variation of fine particle number concentrations over Beijing and surrounding areas in an air quality model with aerosol microphysics

    International Nuclear Information System (INIS)

    Chen, Xueshun; Wang, Zifa; Li, Jie; Chen, Huansheng; Hu, Min; Yang, Wenyi; Wang, Zhe; Ge, Baozhu; Wang, Dawei

    2017-01-01

    In this study, a three-dimensional air quality model with detailed aerosol microphysics (NAQPMS + APM) was applied to simulate the fine particle number size distribution and to explain the spatiotemporal variation of fine particle number concentrations in different size ranges over Beijing and surrounding areas in the haze season (Jan 15 to Feb 13 in 2006). Comparison between observations and the simulation indicates that the model is able to reproduce the main features of the particle number size distribution. The high number concentration of total particles, up to 26600 cm −3 in observations and 39800 cm −3 in the simulation, indicates the severity of pollution in Beijing. We find that primary particles with secondary species coating and secondary particles together control the particle number size distribution. Secondary particles dominate particle number concentration in the nucleation mode. Primary and secondary particles together determine the temporal evolution and spatial pattern of particle number concentration in the Aitken mode. Primary particles dominate particle number concentration in the accumulation mode. Over Beijing and surrounding areas, secondary particles contribute at least 80% of particle number concentration in the nucleation mode but only 10–20% in the accumulation mode. Nucleation mode particles and accumulation mode particles are anti-phased with each other. Nucleation or primary emissions alone could not explain the formation of the particle number size distribution in Beijing. Nucleation has larger effects on ultrafine particles while primary particles emissions are efficient in producing large particles in the accumulation mode. Reduction in primary particle emissions does not always lead to a decrease in the number concentration of ultrafine particles. Measures to reduce fine particle pollution in terms of particle number concentration may be different from those addressing particle mass concentration. - Highlights:

  5. Simulations of longitudinally pumped dye laser amplifier

    International Nuclear Information System (INIS)

    Takehisa, Kiwamu; Takemori, Satoshi

    1995-01-01

    Simulations of a copper laser pumped dye laser amplifier and new designs of the longitudinally pumped dye laser amplifier are presented. The simulations take the consideration of the amplified spontaneous emission (ASE). The new designs utilize a center-hole reflector instead of a dichroic mirror. The simulation results indicate that the poor spatial overlap between the pump beam and the dye beam in the transverse pumping not only reduces the laser output power, but also generates ASE strongly. The results also indicate that the longitudinal pumping is as efficient as the transverse pumping. (author)

  6. A parallel input composite transimpedance amplifier

    Science.gov (United States)

    Kim, D. J.; Kim, C.

    2018-01-01

    A new approach to high performance current to voltage preamplifier design is presented. The design using multiple operational amplifiers (op-amps) has a parasitic capacitance compensation network and a composite amplifier topology for fast, precision, and low noise performance. The input stage consisting of a parallel linked JFET op-amps and a high-speed bipolar junction transistor (BJT) gain stage driving the output in the composite amplifier topology, cooperating with the capacitance compensation feedback network, ensures wide bandwidth stability in the presence of input capacitance above 40 nF. The design is ideal for any two-probe measurement, including high impedance transport and scanning tunneling microscopy measurements.

  7. Fundamentals of RF and microwave transistor amplifiers

    CERN Document Server

    Bahl, Inder J

    2009-01-01

    A Comprehensive and Up-to-Date Treatment of RF and Microwave Transistor Amplifiers This book provides state-of-the-art coverage of RF and microwave transistor amplifiers, including low-noise, narrowband, broadband, linear, high-power, high-efficiency, and high-voltage. Topics covered include modeling, analysis, design, packaging, and thermal and fabrication considerations. Through a unique integration of theory and practice, readers will learn to solve amplifier-related design problems ranging from matching networks to biasing and stability. More than 240 problems are included to help read

  8. Quantum electronics maser amplifiers and oscillators

    CERN Document Server

    Fain, V M; Sanders, J H

    2013-01-01

    Quantum Electronics, Volume 2: Maser Amplifiers and Oscillators deals with the experimental and theoretical aspects of maser amplifiers and oscillators which are based on the principles of quantum electronics. It shows how the concepts and equations used in quantum electronics follow from the basic principles of theoretical physics.Comprised of three chapters, this volume begins with a discussion on the elements of the theory of quantum oscillators and amplifiers working in the microwave region, along with the practical achievements in this field. Attention is paid to two-level paramagnetic ma

  9. Unconditionally stable microwave Si-IMPATT amplifiers

    International Nuclear Information System (INIS)

    Seddik, M.M.

    1986-07-01

    The purpose of this investigation has been the development of an improved understanding of the design and analysis of microwave reflection amplifiers employing the negative resistance property of the IMPATT devices. Unconditionally stable amplifier circuit using a Silicon IMPATT diode is designed. The problems associated with the design procedures and the stability criterion are discussed. A computer program is developed to perform the computations. The stable characteristics of a reflection-type Si-IMPATT amplifier, such as gain, frequency and bandwidth are examined. It was found that at large signal drive levels, 7 dB gain with bandwidth of 800 MHz at 22,5 mA was obtained. (author)

  10. Micro-Arc Oxidation Enhances the Blood Compatibility of Ultrafine-Grained Pure Titanium

    Directory of Open Access Journals (Sweden)

    Lin Xu

    2017-12-01

    Full Text Available Ultrafine-grained pure titanium prepared by equal-channel angular pressing has favorable mechanical performance and does not contain alloy elements that are toxic to the human body. It has potential clinical value in applications such as cardiac valve prostheses, vascular stents, and hip prostheses. To overcome the material’s inherent thrombogenicity, surface-coating modification is a crucial pathway to enhancing blood compatibility. An electrolyte solution of sodium silicate + sodium polyphosphate + calcium acetate and the micro-arc oxidation (MAO technique were employed for in situ oxidation of an ultrafine-grained pure titanium surface. A porous coating with anatase- and rutile-phase TiO2 was generated and wettability and blood compatibility were examined. The results showed that, in comparison with ultrafine-grained pure titanium substrate, the MAO coating had a rougher surface, smaller contact angles for distilled water and higher surface energy. MAO modification effectively reduced the hemolysis rate; extended the dynamic coagulation time, prothrombin time (PT, and activated partial thromboplastin time (APTT; reduced the amount of platelet adhesion and the degree of deformation; and enhanced blood compatibility. In particular, the sample with an oxidation time of 9 min possessed the highest surface energy, largest PT and APTT values, smallest hemolysis rate, less platelet adhesion, a lesser degree of deformation, and more favorable blood compatibility. The MAO method can significantly enhance the blood compatibility of ultrafine-grained pure titanium, increasing its potential for practical applications.

  11. New insights into the formation and resolution of ultra-fine anaphase bridges

    DEFF Research Database (Denmark)

    Chan, Kok Lung; Hickson, Ian D

    2011-01-01

    that are important for preventing Fanconi anemia (FA) in man. As part of an analysis of the roles of these proteins in mitosis, we identified a novel class of anaphase bridge structure, called an ultra-fine anaphase bridge (UFB). These UFBs are also defined by the presence of a SNF2 family protein called PICH...

  12. Ultrafine-grained Al composites reinforced with in-situ Al3Ti filaments

    Czech Academy of Sciences Publication Activity Database

    Krizik, P.; Balog, M.; Nosko, M.; Riglos, M. V. C.; Dvořák, Jiří; Bajana, O.

    2016-01-01

    Roč. 657, MAR (2016), s. 6-14 ISSN 0921-5093 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : Aluminum * Filament * In-situ metal matrix composite * Mechanical properties * Microstructure * Ultrafine-grained Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.094, year: 2016

  13. Preparation of Ultra-fine Calcium Carbonate by a Solvent-free ...

    African Journals Online (AJOL)

    The treatment of calcium chloride with sodium carbonate under solvent-free conditions with a supersonic airflow and at a low heating temperature leads to the synthesis of ultra-fine calcium carbonate. The reaction not only involves mild conditions, a simple operation, and high yields but also gives a high conversion rate.

  14. Fatigue damage of ultrafine-grain copper in very-high cycle fatigue region

    Czech Academy of Sciences Publication Activity Database

    Lukáš, Petr; Kunz, Ludvík; Navrátilová, Lucie; Bokůvka, O.

    2011-01-01

    Roč. 528, - (2011), s. 7036-7040 ISSN 0921-5093 R&D Projects: GA ČR GAP108/10/2001 Institutional research plan: CEZ:AV0Z20410507 Keywords : ultrafine-grained microstructure * ultrasonic fatigue * crack initiation * copper Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 2.003, year: 2011

  15. Microstructure changes in superplastically deformed ultrafine-grained Al-3Mg-0.2Sc alloy

    Czech Academy of Sciences Publication Activity Database

    Král, Petr; Dvořák, Jiří; Kvapilová, Marie; Horita, Z.; Sklenička, Václav

    2015-01-01

    Roč. 5, č. 3 (2015), s. 306-312 ISSN 2218-5046 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : ultrafine-grained microstructure * aluminium alloy * equal-channel angular pressing * electron back scatter diffraction Subject RIV: JJ - Other Materials

  16. Study of thermal stability of ultrafine-grained copper by means of electron back scattering diffraction

    Czech Academy of Sciences Publication Activity Database

    Man, O.; Pantělejev, L.; Kunz, Ludvík

    2010-01-01

    Roč. 51, č. 2 (2010), s. 209-213 ISSN 1345-9678 R&D Projects: GA AV ČR 1QS200410502 Institutional research plan: CEZ:AV0Z20410507 Keywords : ultra-fine grained copper * thermal stability of microstructure * electron back scattering diffraction * grain size * texture Subject RIV: JG - Metallurgy Impact factor: 0.779, year: 2010

  17. Effect of Hydrostatic Pressure on Defect Structure and Durability of Ultrafine-Grained Aluminum

    Czech Academy of Sciences Publication Activity Database

    Betekhtin, V.I.; Kadomtsev, A. G.; Sklenička, Václav; Narykova, M. V.

    2011-01-01

    Roč. 37, č. 10 (2011), s. 977-979 ISSN 1063-7850 Institutional research plan: CEZ:AV0Z20410507 Keywords : defect structure * ultrafine-grained aluminium * durability Subject RIV: JG - Metallurgy Impact factor: 0.565, year: 2011

  18. Soot, organics and ultrafine ash from air- and oxy-fired coal combustion

    Science.gov (United States)

    This paper is concerned with determining the effects of oxy-combustion of coal on the composition of the ultrafine fly ash. To this end, a 10 W externally heated entrained flow furnace was modified to allow the combustion of pulverized coal in flames under practically relevant s...

  19. Automatic error compensation in dc amplifiers

    International Nuclear Information System (INIS)

    Longden, L.L.

    1976-01-01

    When operational amplifiers are exposed to high levels of neutron fluence or total ionizing dose, significant changes may be observed in input voltages and currents. These changes may produce large errors at the output of direct-coupled amplifier stages. Therefore, the need exists for automatic compensation techniques. However, previously introduced techniques compensate only for errors in the main amplifier and neglect the errors induced by the compensating circuitry. In this paper, the techniques introduced compensate not only for errors in the main operational amplifier, but also for errors induced by the compensation circuitry. Included in the paper is a theoretical analysis of each compensation technique, along with advantages and disadvantages of each. Important design criteria and information necessary for proper selection of semiconductor switches will also be included. Introduced in this paper will be compensation circuitry for both resistive and capacitive feedback networks

  20. Stimulated Brillouin scattering threshold in fiber amplifiers

    International Nuclear Information System (INIS)

    Liang Liping; Chang Liping

    2011-01-01

    Based on the wave coupling theory and the evolution model of the critical pump power (or Brillouin threshold) for stimulated Brillouin scattering (SBS) in double-clad fiber amplifiers, the influence of signal bandwidth, fiber-core diameter and amplifier gain on SBS threshold is simulated theoretically. And experimental measurements of SBS are presented in ytterbium-doped double-clad fiber amplifiers with single-frequency hundred nanosecond pulse amplification. Under different input signal pulses, the forward amplified pulse distortion is observed when the pulse energy is up to 660 nJ and the peak power is up to 3.3 W in the pulse amplification with pulse duration of 200 ns and repetition rate of 1 Hz. And the backward SBS narrow pulse appears. The pulse peak power equals to SBS threshold. Good agreement is shown between the modeled and experimental data. (authors)

  1. Complementary DNA-amplified fragment length polymorphism ...

    African Journals Online (AJOL)

    Complementary DNA-amplified fragment length polymorphism (AFLP-cDNA) analysis of differential gene expression from the xerophyte Ammopiptanthus mongolicus in response to cold, drought and cold together with drought.

  2. Behavior of MOSFET Amplifier in Radiation Fields

    International Nuclear Information System (INIS)

    Sharshar, K.A.A.; Ashry, M.

    2000-01-01

    MOSFET type 2 N 3823 characteristics and its application as an amplifier are analyzed including the effects of gamma, electron beam 1.5 MeV 25 m A and neutron flux. The 1-V characteristics, transfer curve, and the frequency response of the amplifier, and the amplification factor(A v 0 are discussed with MOSFET circuit parameters. The drain current and the amplitude of the output signal decrease as the absorbed dose increases. The measured values of the amplified signal are attenuated by 30% and 6% after exposing the MOSFET to gamma radiation and electron beam at the same dose respectively. Also for exposure to 4x10 13 N/cm 3 neutrons decreased the measured value of the amplified signal by 73% of the initial values. The decrease in the gain of the MOSFET is due to the degradation of the transconductance. It is also noticed that percentage of the decrease depends on the type of radiation

  3. Quantum-Limited Directional Amplifiers with Optomechanics

    Science.gov (United States)

    Malz, Daniel; Tóth, László D.; Bernier, Nathan R.; Feofanov, Alexey K.; Kippenberg, Tobias J.; Nunnenkamp, Andreas

    2018-01-01

    Directional amplifiers are an important resource in quantum-information processing, as they protect sensitive quantum systems from excess noise. Here, we propose an implementation of phase-preserving and phase-sensitive directional amplifiers for microwave signals in an electromechanical setup comprising two microwave cavities and two mechanical resonators. We show that both can reach their respective quantum limits on added noise. In the reverse direction, they emit thermal noise stemming from the mechanical resonators; we discuss how this noise can be suppressed, a crucial aspect for technological applications. The isolation bandwidth in both is of the order of the mechanical linewidth divided by the amplitude gain. We derive the bandwidth and gain-bandwidth product for both and find that the phase-sensitive amplifier has an unlimited gain-bandwidth product. Our study represents an important step toward flexible, on-chip integrated nonreciprocal amplifiers of microwave signals.

  4. Electrospinning of oriented and nonoriented ultrafine fibers of biopolymers

    Science.gov (United States)

    Vu, David

    2005-07-01

    Chitosan has long been known as a biocompatible and biodegradable material suitable for tissue engineering applications. Unfortunately, conventional chitosan solutions cannot be used for electrospinning due to their high conductivity, viscosity and surface tension. We have developed a method to produce clear chitosan solutions with conductivities, surface tension and viscosities that facilitate their processing into micron and submicron fibers via electrospinning. Acetic acid, carbon dioxide and organic solvents are key ingredients in preparing the chitosan solutions. Oriented and non oriented chitosan fibers were produced with the ultimate goal of designing a suitable tissue engineering scaffold. Circularly oriented, continuous, and aligned nanofibers were produced via this technique in the form of a thin membrane or fibrous "mat". Chitosan fiber diameters ranged from 5 micrometers down to 100 nanometers. The structure and mechanical properties of oriented and randomly aligned chitosan fiber deposits could potentially be exploited for cartilage tissue engineering. Ultrafine fibers of starch acetate (SA) also were prepared by the electrospinning process. In this study, solvent mixtures based on DMF, DMSO, pyrindine, acetic acid, acetone, THF, DMC, chloroform were used. A two-solvent formulation was used to study the effect of viscosity, surface tension, and conductivity to the fiber diameter. Also, water and ethanol were used to decrease the boiling point of the solvent, and to make bundled fibers. Several techniques such as scanning electron microscopy, conductmetry, viscometry, and tensiometry were used in this study. The results showed that the combined effects of viscosity, surface tension, and conductivity are of great importance in controlling the diameter of the fibers. We were able to produce SA fibers that was less than 40 nm in diameter. The dependence of fiber diameter on flow-rate, electric field and solvents also was investigated. A rotating disk and a

  5. Particle size dependence on oxygen reduction reaction activity of electrodeposited TaOx catalysts in acidic media

    KAUST Repository

    Seo, J.

    2013-11-13

    The size dependence of the oxygen reduction reaction activity was studied for TaOx nanoparticles electrodeposited on carbon black for application to polymer electrolyte fuel cells (PEFCs). Compared with a commercial Ta2O5 material, the ultrafine oxide nanoparticles exhibited a distinctively high onset potential different from that of the bulky oxide particles.

  6. Manhattan equation for the operational amplifier

    OpenAIRE

    Mishonov, Todor M.; Danchev, Victor I.; Petkov, Emil G.; Gourev, Vassil N.; Dimitrova, Iglika M.; Varonov, Albert M.

    2018-01-01

    A differential equation relating the voltage at the output of an operational amplifier $U_0$ and the difference between the input voltages ($U_{+}$ and $U_{-}$) has been derived. The crossover frequency $f_0$ is a parameter in this operational amplifier master equation. The formulas derived as a consequence of this equation find applications in thousands of specifications for electronic devices but as far as we know, the equation has never been published. Actually, the master equation of oper...

  7. Distributed amplifier using Josephson vortex flow transistors

    International Nuclear Information System (INIS)

    McGinnis, D.P.; Beyer, J.B.; Nordman, J.E.

    1986-01-01

    A wide-band traveling wave amplifier using vortex flow transistors is proposed. A vortex flow transistor is a long Josephson junction used as a current controlled voltage source. The dual nature of this device to the field effect transistor is exploited. A circuit model of this device is proposed and a distributed amplifier utilizing 50 vortex flow transistors is predicted to have useful gain to 100 GHz

  8. Multiple excitation regenerative amplifier inertial confinement system

    International Nuclear Information System (INIS)

    George, V.E.; Haas, R.A.; Krupke, W.F.; Schlitt, L.G.

    1980-01-01

    The invention relates to apparatus and methods for producing high intensity laser radiation generation which is achieved through an optical amplifier-storage ring design. One or two synchronized, counterpropagating laser pulses are injected into a regenerative amplifier cavity and amplified by gain media which are pumped repetitively by electrical or optical means. The gain media excitation pulses are tailored to efficiently amplify the laser pulses during each transit. After the laser pulses have been amplified to the desired intensity level, they are either switched out of the cavity by some switch means, as for example an electro-optical device, for any well known laser end uses, or a target means may be injected into the regenerative amplifier cavity in such a way as to intercept simultaneously the counterpropagating laser pulses. One such well known end uses to which this invention is intended is for production of high density and temperature plasmas suitable for generating neutrons, ions and x-rays and for studying matter heated by high intensity laser radiation

  9. Microstructure of warm rolling and pearlitic transformation of ultrafine-grained GCr15 steel

    International Nuclear Information System (INIS)

    Sun, Jun-Jie; Lian, Fu-Liang; Liu, Hong-Ji; Jiang, Tao; Guo, Sheng-Wu; Du, Lin-Xiu; Liu, Yong-Ning

    2014-01-01

    Pearlitic transformation mechanisms have been investigated in ultra-fine grained GCr15 steel. The ultrafine-grained steel, whose grain size was less than 1 μm, was prepared by thermo-mechanical treatment at 873 K and then annealing at 923 K for 2 h. Pearlitic transformation was conducted by reheating the ultra-fine grained samples at 1073 K and 1123 K for different periods of time and then cooling in air. Scanning electron microscope observation shows that normal lamellar pearlite, instead of granular cementite and ferrite, cannot be formed when the grain size is approximately less than 4(± 0.6) μm, which yields a critical grain size for normal lamellar pearlitic transformations in this chromium alloyed steel. The result confirms that grain size has a great influence on pearlitic transformation by increasing the diffusion rate of carbon atoms in the ultra-fine grained steel, and the addition of chromium element doesn't change this pearlitic phase transformation rule. Meanwhile, the grain growth rate is reduced by chromium alloying, which is beneficial to form fine grains during austenitizing, thus it facilitating pearlitic transformation by divorced eutectoid transformation. Moreover, chromium element can form a relatively high gradient in the frontier of the undissolved carbide, which promotes carbide formation in the frontier of the undissolved carbide, i.e., chromium promotes divorced eutectoid transformation. - Highlights: • Ultrafine-grained GCr15 steel was obtained by warm rolling and annealing technology. • Reduction of grain size makes pearlite morphology from lamellar to granular. • Adding Cr does not change normal pearlitic phase transformation rule in UFG steel. • Cr carbide resists grain growth and facilitates pearlitic transformation by DET

  10. Radiation-induced copolymerization of styrene/n-butyl acrylate in the presence of ultra-fine powdered styrene-butadiene rubber

    Energy Technology Data Exchange (ETDEWEB)

    Yu Haibo [Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Peng Jing [Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)], E-mail: jpeng@pku.edu.cn; Zhai Maolin; Li Jiuqiang; Wei Genshuan [Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Qiao Jinliang [Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); SINOPEC Beijing Research Institute of Chemical Industry, Beijing 100013 (China)

    2007-11-15

    Styrene (St)/n-butyl acrylate (BA) copolymers were prepared by two-stage polymerization: St/BA was pre-polymerized to a viscous state by bulk polymerization with initiation by benzoyl peroxide (BPO) followed by {sup 60}Co {gamma}-ray radiation curing. The resultant copolymers had higher molecular weight and narrower molecular weight distribution than conventional methods. After incorporation of ultra-fine powdered styrene-butadiene rubber (UFSBR) with a particle size of 100 nm in the monomer, the glass transition temperature (T{sub g}) of St-BA copolymer increased at low rubber content. Both the St-BA copolymer and the St-BA copolymer/UFSBR composites had good transparency at BA content below 40%.

  11. High efficiency RF amplifier development over wide dynamic range for accelerator application

    Science.gov (United States)

    Mishra, Jitendra Kumar; Ramarao, B. V.; Pande, Manjiri M.; Joshi, Gopal; Sharma, Archana; Singh, Pitamber

    2017-10-01

    Superconducting (SC) cavities in an accelerating section are designed to have the same geometrical velocity factor (βg). For these cavities, Radio Frequency (RF) power needed to accelerate charged particles varies with the particle velocity factor (β). RF power requirement from one cavity to other can vary by 2-5 dB within the accelerating section depending on the energy gain in the cavity and beam current. In this paper, we have presented an idea to improve operating efficiency of the SC RF accelerators using envelope tracking technique. A study on envelope tracking technique without feedback is carried out on a 1 kW, 325 MHz, class B (conduction angle of 180 degrees) tuned load power amplifier (PA). We have derived expressions for the efficiency and power output for tuned load amplifier operating on the envelope tracking technique. From the derived expressions, it is observed that under constant load resistance to the device (MOSFET), optimum amplifier efficiency is invariant whereas output power varies with the square of drain bias voltage. Experimental results on 1 kW PA module show that its optimum efficiency is always greater than 62% with variation less than 5% from mean value over 7 dB dynamic range. Low power amplifier modules are the basic building block for the high power amplifiers. Therefore, results for 1 kW PA modules remain valid for the high power solid state amplifiers built using these PA modules. The SC RF accelerators using these constant efficiency power amplifiers can improve overall accelerator efficiency.

  12. Aerosol particle mixing state, refractory particle number size distributions and emission factors in a polluted urban environment: Case study of Metro Manila, Philippines

    Science.gov (United States)

    Kecorius, Simonas; Madueño, Leizel; Vallar, Edgar; Alas, Honey; Betito, Grace; Birmili, Wolfram; Cambaliza, Maria Obiminda; Catipay, Grethyl; Gonzaga-Cayetano, Mylene; Galvez, Maria Cecilia; Lorenzo, Genie; Müller, Thomas; Simpas, James B.; Tamayo, Everlyn Gayle; Wiedensohler, Alfred

    2017-12-01

    Ultrafine soot particles (black carbon, BC) in urban environments are related to adverse respiratory and cardiovascular effects, increased cases of asthma and premature deaths. These problems are especially pronounced in developing megacities in South-East Asia, Latin America, and Africa, where unsustainable urbanization ant outdated environmental protection legislation resulted in severe degradation of urban air quality in terms of black carbon emission. Since ultrafine soot particles do often not lead to enhanced PM10 and PM2.5 mass concentration, the risks related to ultrafine particle pollution may therefore be significantly underestimated compared to the contribution of secondary aerosol constituents. To increase the awareness of the potential toxicological relevant problems of ultrafine black carbon particles, we conducted a case study in Metro Manila, the capital of the Philippines. Here, we present a part of the results from a detailed field campaign, called Manila Aerosol Characterization Experiment (MACE, 2015). Measurements took place from May to June 2015 with the focus on the state of mixing of aerosol particles. The results were alarming, showing the abundance of externally mixed refractory particles (soot proxy) at street site with a maximum daily number concentration of approximately 15000 #/cm3. That is up to 10 times higher than in cities of Western countries. We also found that the soot particle mass contributed from 55 to 75% of total street site PM2.5. The retrieved refractory particle number size distribution appeared to be a superposition of 2 ultrafine modes at 20 and 80 nm with a corresponding contribution to the total refractory particle number of 45 and 55%, respectively. The particles in the 20 nm mode were most likely ash from metallic additives in lubricating oil, tiny carbonaceous particles and/or nucleated and oxidized organic polymers, while bigger ones (80 nm) were soot agglomerates. To the best of the authors' knowledge, no other

  13. Direct printing of patterned three-dimensional ultrafine fibrous scaffolds by stable jet electrospinning for cellular ingrowth

    International Nuclear Information System (INIS)

    Yuan, Huihua; Zhou, Qihui; Li, Biyun; Bao, Min; Lou, Xiangxin; Zhang, Yanzhong

    2015-01-01

    Electrospinning has been widely used to produce ultrafine fibers in microscale and nanoscale; however, traditional electrospinning processes are currently beset by troublesome limitations in fabrication of 3D periodic porous structures because of the chaotic nature of the electrospinning jet. Here we report a novel strategy to print 3D poly(L-lactic acid) (PLLA) ultrafine fibrous scaffolds with the fiber diameter of approximately 2 μm by combining a stable jet electrospinning method and an X-Y stage technique. Our approach allows linearly deposited electrospun ultrafine fibers to assemble into 3D structures with tunable pore sizes and desired patterns. Process conditions (e.g., plotting speed, feeding rate, and collecting distance) were investigated in order to achieve stable jet printing of ultrafine PLLA fibers. The proposed 3D scaffold was successfully used for cell penetration and growth, demonstrating great potential for tissue engineering applications. (paper)

  14. Enhanced protective properties of epoxy/polyaniline-camphorsulfonate nanocomposite coating on an ultrafine-grained metallic surface

    International Nuclear Information System (INIS)

    Pour-Ali, Sadegh; Kiani-Rashid, Alireza; Babakhani, Abolfazl; Davoodi, Ali

    2016-01-01

    Highlights: • Preparing mild steel surface with ultrafine grains by wire brushing process. • Performance of a smart coating on micro- and nano-crystalline surfaces. • Corrosion evaluation, surface analysis and ac/dc electrochemical measurements. • Ultrafine surface grains improve protective behavior of epoxy/PANI-CSA coating. - Abstract: An ultrafine-grained surface layer on mild steel substrate with average grain size of 77 nm was produced through wire brushing process. Surface grain size was determined through transmission electron microscopy and X-ray diffraction methods. This substrate was coated with epoxy and an in situ synthesized epoxy/polyaniline-camphorsulfonate (epoxy/PANI-CSA) nanocomposite. The corrosion behavior was studied by open circuit potential, potentiodynamic polarization and impedance measurements. Results of electrochemical tests evidenced the enhanced protective properties of epoxy/PANI-CSA coating on the substrate with ultrafine-grained surface.

  15. Enhanced protective properties of epoxy/polyaniline-camphorsulfonate nanocomposite coating on an ultrafine-grained metallic surface

    Energy Technology Data Exchange (ETDEWEB)

    Pour-Ali, Sadegh, E-mail: pourali2020@ut.ac.ir; Kiani-Rashid, Alireza; Babakhani, Abolfazl; Davoodi, Ali

    2016-07-15

    Highlights: • Preparing mild steel surface with ultrafine grains by wire brushing process. • Performance of a smart coating on micro- and nano-crystalline surfaces. • Corrosion evaluation, surface analysis and ac/dc electrochemical measurements. • Ultrafine surface grains improve protective behavior of epoxy/PANI-CSA coating. - Abstract: An ultrafine-grained surface layer on mild steel substrate with average grain size of 77 nm was produced through wire brushing process. Surface grain size was determined through transmission electron microscopy and X-ray diffraction methods. This substrate was coated with epoxy and an in situ synthesized epoxy/polyaniline-camphorsulfonate (epoxy/PANI-CSA) nanocomposite. The corrosion behavior was studied by open circuit potential, potentiodynamic polarization and impedance measurements. Results of electrochemical tests evidenced the enhanced protective properties of epoxy/PANI-CSA coating on the substrate with ultrafine-grained surface.

  16. Extruded Al-Al2O3 composites formed in situ during consolidation of ultrafine Al powders: Effect of the powder surface area

    International Nuclear Information System (INIS)

    Balog, Martin; Simancik, Frantisek; Walcher, Martin; Rajner, Walter; Poletti, Cecilia

    2011-01-01

    Highlights: → 25 gas atomised Al 99.5% powders with particle size 2 O 3 dispersoids. → Compacts showed good thermal stability due to grain pinning of Al 2 O 3 dispersoids. - Abstract: Twenty-five samples of commercially available, gas-atomised Al (99.5%) powders with particle sizes 2 O 3 composites formed in situ during extrusion. The effect of particle size, surface area, oxygen content and atomisation atmosphere of the powder on the microstructure and mechanical properties of the extruded compacts were studied by Brunauer, Emmett, Teller (BET) analysis, hot gas extraction, scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and tensile tests. Thermal stability of the compacts and the individual strengthening mechanisms operating in the compacts were discussed. It was found that the properties of the compacts stemmed from the extraordinary grain boundary strengthening effect of the ultrafine-grained compacts due to their microstructures. The efficiency of the grain boundary strengthening was significantly enhanced by the presence of nano-metric Al 2 O 3 dispersoids introduced in situ. The strength of the compacts was closely related to the surface area of the powder particles. In addition, the entrapped gasses and chemically bonded humidity had a negative effect on the mechanical properties of the compacts.

  17. Advances in high-power rf amplifiers

    International Nuclear Information System (INIS)

    Tallerico, P.J.

    1979-01-01

    Several powerful accelerators and storage rings are being considered that will require tens or even hundreds of megawatts of continuous rf power. The economics of such large machines can be dictated by the cost and efficiency of the rf amplifiers. The overall design and performance of such narrow-band amplifiers, operating in the 50- to 1500-MHz region, are being theoretically studied as a function of frequency to determine the optimum rf amplifier output power, gain, efficiency, and dc power requirements. The state of the art for three types of amplifiers (gridded tubes, klystrons, and gyrocons) is considered and the development work necessary to improve each is discussed. The gyrocon is a new device, hence its various embodiments are discussed in detail. The Soviet designs are reviewed and the gyrocon's strengths and weaknesses are compared to other types of microwave amplifiers. The primary advantages of the gyrocon are the very large amount of power available from a single device and the excellent efficiency and stable operation. The klystron however, has much greater gain and is simpler mechanically. At very low frequencies, the small size of the gridded tube makes it the optimum choice for all but the most powerful systems

  18. Transpermeance Amplifier Applied to Magnetic Bearings

    Directory of Open Access Journals (Sweden)

    Jossana Ferreira

    2017-02-01

    Full Text Available The most conventional approach of controlling magnetic forces in active magnetic bearings (AMBs is through current feedback amplifiers: transconductance. This enables the operation of the AMB to be understood in terms of a relatively simple current-based model as has been widely reported on in the literature. The alternative notion of using transpermeance amplifiers, which approximate the feedback of gap flux rather than current, has been in commercial use in some form for at least thirty years, however is only recently seeing more widespread acceptance as a commercial standard. This study explores how such alternative amplifiers should be modeled and then examines the differences in behavior between AMBs equipped with transconductance and transpermeance amplifiers. The focus of this study is on two aspects. The first is the influence of rotor displacement on AMB force, commonly modeled as a constant negative equivalent mechanical stiffness, and it is shown that either scheme actually leads to a finite bandwidth effect, but that this bandwidth is much lower when transpermeance is employed. The second aspect is the influence of eddy currents. Using a very simple model of eddy currents (a secondary short-circuited coil, it is demonstrated that transpermeance amplifiers can recover significant actuator bandwidth compared with transconductance, but at the cost of needing increased peak current headroom.

  19. Wideband Low Noise Amplifiers Exploiting Thermal Noise Cancellation

    NARCIS (Netherlands)

    Bruccoleri, F.; Klumperink, Eric A.M.; Nauta, Bram

    2005-01-01

    Low Noise Amplifiers (LNAs) are commonly used to amplify signals that are too weak for direct processing for example in radio or cable receivers. Traditionally, low noise amplifiers are implemented via tuned amplifiers, exploiting inductors and capacitors in resonating LC-circuits. This can render

  20. Solid-state disk amplifiers for fusion-laser systems

    Energy Technology Data Exchange (ETDEWEB)

    Martin, W.E.; Trenholme, J.B.; Linford, G.J.; Yarema, S.M.; Hurley, C.A.

    1981-09-01

    We review the design, performance, and operation of large-aperture (10 to 46 cm) solid-state disk amplifiers for use in laser systems. We present design data, prototype tests, simulations, and projections for conventional cylindrical pump-geometry amplifiers and rectangular pump-geometry disk amplifiers. The design of amplifiers for the Nova laser system is discussed.