Comparison of endotoxin and particle bounce in Marple cascade samplers with and without impaction grease.

PubMed

Kirychuk, Shelley P; Reynolds, Stephen J; Koehncke, Niels; Nakatsu, J; Mehaffy, John

2009-01-01

The health of persons engaged in agricultural activities are often related or associated with environmental exposures in their workplace. Accurately measuring, analyzing, and reporting these exposures is paramount to outcomes interpretation. This paper describes issues related to sampling air in poultry barns with a cascade impactor. Specifically, the authors describe how particle bounce can affect measurement outcomes and how the use of impaction grease can impact particle bounce and laboratory analyses such as endotoxin measurements. This project was designed to (1) study the effect of particle bounce in Marple cascade impactors that use polyvinyl chloride (PVC) filters; (2) to determine the effect of impaction grease on endotoxin assays when sampling poultry barn dust. A pilot study was undertaken utilizing six-stage Marple cascade impactors with PVC filters. Distortion of particulate size distributions and the effects of impaction grease on endotoxin analysis in samples of poultry dust distributed into a wind tunnel were studied. Although there was no significant difference in the overall dust concentration between utilizing impaction grease and not, there was a greater than 50% decrease in the mass median aerodynamic diameter (MMAD) values when impaction grease was not utilized. There was no difference in airborne endotoxin concentration or endotoxin MMAD between filters treated with impaction grease and those not treated. The results indicate that particle bounce should be a consideration when sampling poultry barn dust with Marple samplers containing PVC filters with no impaction grease. Careful consideration should be given to the utilization of impaction grease on PVC filters, which will undergo endotoxin analysis, as there is potential for interference, particularly if high or low levels of endotoxin are anticipated.

Calibration and field application of a Sierra Model 235 cascade impactor.

PubMed

Knuth, R H

1984-06-01

A Sierra Model 235 slotted impactor was used to measure the particle size distribution of ore dust in uranium concentrating mills. The impactor was calibrated at a flow rate of 0.21 m3/min, using solid monodisperse particles of methylene blue and an impaction surface of Whatman #41 filter paper soaked in mineral oil. The reduction from the impactor's design flow rate of 1.13 m3/min (40 cfm) to 0.21 m3/min (7.5 cfm), a necessary adjustment because of the anticipated large particles sizes of ore dust, increased the stage cut-off diameters by an average factor of 2.3. Evaluation of field test results revealed that the underestimation of mass median diameters, often caused by the rebound and reentrainment of solid particles from dry impaction surfaces, was virtually eliminated by using the oiled Whatman #41 impaction surface.

Study of the atmospheric aerosol composition in equatorial Africa using PIXE as analytical technique

NASA Astrophysics Data System (ADS)

Maenhaut, W.; Akilimali, K.

1987-03-01

Small Nuclepore total filter holders and a single orifice 8-stage cascade impactor were used to collect atmospheric aerosol samples in Kinshasa, Zaire, and Butare, Rwanda. The samples were analyzed for about 20 elements by means of the PIXE technique. The results obtained for parallel samples, taken with two total filter holders and one cascade impactor, were generally in excellent agreement, suggesting that the different samplers collected very similar aerosol particle populations. Most elements were associated with a crustal dust dispersion source, which may include road dust dispersal. The Butare samples, particularly those collected during the night, were significantly influenced by biomass burning, as was deduced from enhanced filter blackness and noncrustal K levels. The pyrogenic component also contained P, S, Mn and Rb. Br and Pb were highly enriched at both locations, indicating that automotive sources had a strong influence on the aerosol composition.

PROCEEDINGS: ADVANCES IN PARTICLE SAMPLING AND MEASUREMENT (ASHEVILLE, NC, MAY 1978)

EPA Science Inventory

The proceedings consist of 17 papers on improved instruments and techniques for sampling and measuring particulate emissions and aerosols; e.g., cascade impactors, cyclone collectors, and diffusion-battery/nuclei-counter combinations. Transmissometers and instruments for measurin...

Zhamanshin astrobleme provides evidence for carbonaceous chondrite and post-impact exchange between ejecta and Earth's atmosphere.

PubMed

Magna, Tomáš; Žák, Karel; Pack, Andreas; Moynier, Frédéric; Mougel, Bérengère; Peters, Stefan; Skála, Roman; Jonášová, Šárka; Mizera, Jiří; Řanda, Zdeněk

2017-08-09

Chemical fingerprints of impacts are usually compromised by extreme conditions in the impact plume, and the contribution of projectile matter to impactites does not often exceed a fraction of per cent. Here we use chromium and oxygen isotopes to identify the impactor and impact-plume processes for Zhamanshin astrobleme, Kazakhstan. ε 54 Cr values up to 1.54 in irghizites, part of the fallback ejecta, represent the 54 Cr-rich extremity of the Solar System range and suggest a CI-like chondrite impactor. Δ 17 O values as low as -0.22‰ in irghizites, however, are incompatible with a CI-like impactor. We suggest that the observed 17 O depletion in irghizites relative to the terrestrial range is caused by partial isotope exchange with atmospheric oxygen (Δ 17 O = -0.47‰) following material ejection. In contrast, combined Δ 17 O-ε 54 Cr data for central European tektites (distal ejecta) fall into the terrestrial range and neither impactor fingerprint nor oxygen isotope exchange with the atmosphere are indicated.Identifying the original impactor from craters remains challenging. Here, the authors use chromium and oxygen isotopes to indicate that the Zhamanshin astrobleme impactor was a carbonaceous chrondrite by demonstrating that depleted 17O values are due to exchange with atmospheric oxygen.

Evaluation of the SKC DPM cassette for monitoring diesel particulate matter in coal mines.

PubMed

Noll, James D; Birch, Eileen

2004-12-01

In a previous study, the efficacy of commercial and prototype impactors for sampling diesel particulate matter (DPM) in coal mines was investigated. Laboratory and field samples were collected on quartz-fiber filters and analyzed for organic and elemental carbon. Coal dust contributed a minimal amount of elemental carbon when commercial cascade impactors and prototype impactors, designed by the University of Minnesota (UMN) and the US Bureau of Mines (BOM), were used to collect submicrometer dust fractions. Other impactors were not as effective at excluding coal dust. The impactors evaluated in that study were either not commercially available or were multi-stage, expensive, and difficult to use for personal measurements. A commercial version of the BOM impactor, called the DPM Cassette, was recently introduced by SKC. Tests were conducted to evaluate the performance of the DPM Cassette for measuring diesel-source elemental carbon in the presence of coal dust. Bituminous coals from three mines in two different coal provinces were examined. The dust particle diameters were small and the coal dust contained a high percentage of carbon, thereby giving a worst-case condition for non-anthracite coal mines. Results for the DPM Cassette were essentially identical to those obtained by the BOM impactors in a previous study. At a respirable coal dust concentration of 5.46 mg m(-3), which is 3.8 times the regulatory limit, the DPM Cassette collected only 34 microg m(-3) of coal-source elemental carbon.

DEVELOPMENT AND LABORATORY PERFORMANCE EVALUATION OF A PERSONAL CASCADE IMPACTOR. (R825270)

EPA Science Inventory

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...

Design and Calibration of a High Volume Cascade Impactor

ERIC Educational Resources Information Center

Gussman, R. A.; And Others

1973-01-01

This study was to develop an air sampling device capable of classifying large quantities of airborne particulate matter into discrete size fractions. Such fractionation will facilitate chemical analysis of the various particulate pollutants and thereby provide a more realistic assessment of the effects of particulate matter on human beings. (BL)

CHARACTERIZATION OF AMBIENT PM2.5 AEROSOL AT A SOUTHEASTERN US SITE: FOURIER TRANSFORM INFRARED ANALYSIS OR PARTICLE PHASE

EPA Science Inventory

During a field study in the summer of 2000 in the Research Triangle Park (RTP), aerosol samples were collected using a five stage cascade impactor and subsequently analyzed using Fourier Transform Infrared Spectroscopy (FTIR). The impaction surfaces were stainless steel disks....

Final report on fiscal year 1992 activities for the environmental monitors line-loss study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kenoyer, J.L.

The work performed on this Environmental Monitors Line-Loss Study has been performed under Contract Numbers MLW-SVV-073750 and MFH-SVV-207554. Work on the task was initiated mid-December 1991, and this report documents and summarizes the work performed through January 18, 1993. The sections included in this report summarize the work performed on the Environmental Monitors Line-Loss Study. The sections included in this report are arranged to reflect individual sub-tasks and include: descriptions of measurement systems and procedures used to obtain cascade impactor samples and laser spectrometer measurements from multiple stacks and locations; information on data acquisition, analyses, assessment, and software; discussion ofmore » the analyses and measurement results from the cascade impactor and laser spectrometer systems and software used; discussion on the development of general test methods and procedures for line-loss determinations; an overall summary and specific conclusions that can be made with regard to efforts performed on this task during FY 1992 and FY 1993. Supporting information for these sections is included in this report as appendices.« less

Aerosol Physics Considerations for Using Cerium Oxide CeO 2 as a Surrogate for Plutonium Oxide PuO 2 in Airborne Release Fraction Measurements for Storage Container Investigations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, Murray E.; Tao, Yong

Cerium oxide (CeO2) dust is recommended as a surrogate for plutonium oxide (PuO2) in airborne release fraction experiments. The total range of applicable particle sizes for PuO2 extends from 0.0032 μm (the diameter of a single PuO2 molecule) to 10 μm (the defined upper boundary for respirable particles). For particulates with a physical particle diameter of 1.0 μm, the corresponding aerodynamic diameters for CeO2 and PuO2 are 2.7 μm and 3.4 μm, respectively. Cascade impactor air samplers are capable of measuring the size distributions of CeO2 or PuO2 particulates. In this document, the aerodynamic diameters for CeO2 and PuO2 weremore » calculated for seven different physical diameters (0.0032, 0.02, 0.11, 0.27, 1.0, 3.2, and 10 μm). For cascade impactor measurements, CeO2 and PuO2 particulates with the same physical diameter would be collected onto the same or adjacent collection substrates. The difference between the aerodynamic diameter of CeO2 and PuO2 particles (that have the same physical diameter) is 39% of the resolution of a twelve-stage MSP Inc. 125 cascade impactor, and 34% for an eight-stage Andersen impactor. An approach is given to calculate the committed effective dose (CED) coefficient for PuO2 aerosol particles, compared to a corresponding aerodynamic diameter of CeO2 particles. With this approach, use of CeO2 as a surrogate for PuO2 material would follow a direct conversion based on a molar equivalent. In addition to the analytical information developed for this document, several US national labs have published articles about the use of CeO2 as a PuO2 surrogate. Different physical and chemical aspects were considered by these investigators, including thermal properties, ceramic formulations, cold pressing, sintering, molecular reactions, and mass loss in high temperature gas flows. All of those US national lab studies recommended the use of CeO2 as a surrogate material for PuO2.« less

Method for measuring the size distribution of airborne rhinovirus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russell, M.L.; Goth-Goldstein, R.; Apte, M.G.

About 50% of viral-induced respiratory illnesses are caused by the human rhinovirus (HRV). Measurements of the concentrations and sizes of bioaerosols are critical for research on building characteristics, aerosol transport, and mitigation measures. We developed a quantitative reverse transcription-coupled polymerase chain reaction (RT-PCR) assay for HRV and verified that this assay detects HRV in nasal lavage samples. A quantitation standard was used to determine a detection limit of 5 fg of HRV RNA with a linear range over 1000-fold. To measure the size distribution of HRV aerosols, volunteers with a head cold spent two hours in a ventilated research chamber.more » Airborne particles from the chamber were collected using an Andersen Six-Stage Cascade Impactor. Each stage of the impactor was analyzed by quantitative RT-PCR for HRV. For the first two volunteers with confirmed HRV infection, but with mild symptoms, we were unable to detect HRV on any stage of the impactor.« less

COMPACT CASCADE IMPACTS

DOEpatents

Lippmann, M.

1964-04-01

A cascade particle impactor capable of collecting particles and distributing them according to size is described. In addition the device is capable of collecting on a pair of slides a series of different samples so that less time is required for the changing of slides. Other features of the device are its compactness and its ruggedness making it useful under field conditions. Essentially the unit consists of a main body with a series of transverse jets discharging on a pair of parallel, spaced glass plates. The plates are capable of being moved incremental in steps to obtain the multiple samples. (AEC)

Product Quality Research Institute evaluation of cascade impactor profiles of pharmaceutical aerosols: part 2--evaluation of a method for determining equivalence.

PubMed

Christopher, David; Adams, Wallace P; Lee, Douglas S; Morgan, Beth; Pan, Ziqing; Singh, Gur Jai Pal; Tsong, Yi; Lyapustina, Svetlana

2007-01-19

The purpose of this article is to present the thought process, methods, and interim results of a PQRI Working Group, which was charged with evaluating the chi-square ratio test as a potential method for determining in vitro equivalence of aerodynamic particle size distribution (APSD) profiles obtained from cascade impactor measurements. Because this test was designed with the intention of being used as a tool in regulatory review of drug applications, the capability of the test to detect differences in APSD profiles correctly and consistently was evaluated in a systematic way across a designed space of possible profiles. To establish a "base line," properties of the test in the simplest case of pairs of identical profiles were studied. Next, the test's performance was studied with pairs of profiles, where some difference was simulated in a systematic way on a single deposition site using realistic product profiles. The results obtained in these studies, which are presented in detail here, suggest that the chi-square ratio test in itself is not sufficient to determine equivalence of particle size distributions. This article, therefore, introduces the proposal to combine the chi-square ratio test with a test for impactor-sized mass based on Population Bioequivalence and describes methods for evaluating discrimination capabilities of the combined test. The approaches and results described in this article elucidate some of the capabilities and limitations of the original chi-square ratio test and provide rationale for development of additional tests capable of comparing APSD profiles of pharmaceutical aerosols.

Adapting the Abbreviated Impactor Measurement (AIM) concept to make appropriate inhaler aerosol measurements to compare with clinical data: a scoping study with the "Alberta" idealized throat (AIT) inlet.

PubMed

Mitchell, Jolyon; Copley, Mark; Sizer, Yvonne; Russell, Theresa; Solomon, Derek

2012-08-01

The Abbreviated Impactor Measurement (AIM) concept simplifies determination of aerodynamic size metrics for inhaler quality control testing. A similar approach is needed to compare in vitro particle size distribution metrics with human respiratory tract (HRT) deposition. An abbreviated impactor based on the Andersen eight-stage cascade impactor (ACI) was developed having two size-fractionating stages with cut-points at 4.7 and 1.1 μm aerodynamic diameter at 28.3 L/min, to distinguish between coarse (CPM), fine (FPM), and extra-fine (EPM) mass fractions likely to deposit in the oropharynx, airways of the lungs, or be exhaled, respectively. In vitro data were determined for pressurized metered dose inhaler (pMDI)-delivered salbutamol (100 μg/actuation ex valve) with an "Alberta" idealized adult upper airway (throat) inlet (AIM-pHRT). Corresponding benchmark data for a full resolution Andersen eight-stage cascade impactor with "Alberta" idealized throat (ACI-AIT) and ACI-Ph.Eur./USP inlet were obtained with the same product. Mass recoveries (μg/actuation; mean ± SD) were equivalent at 100.5 ± 0.7; 97.2 ± 4.9 and 101.5 ± 9.5 for the AIM-pHRT, ACI-AIT, and ACI-Ph.Eur./USP induction port, respectively [one-way analysis of variance (ANOVA), p=0.64]. Corresponding values of CPM were 59.2 ± 4.2; 58.4 ± 2.4, and 65.6 ± 5.8; the AIT captured larger particles more efficiently than the Ph.Eur./USP induction port, so that less large particle mass was apparent in the upper stages of the ACI-AIT (p ≤ 0.037). Equivalent values of FPM were similar regardless of inlet/abbreviation at 41.3 ± 4.2; 38.7 ± 3.0, and 35.9 ± 3.8 (p=0.054), and EPM measures (1.7 ± 0.3; 2.0 ± 0.5; 2.1 ± 0.3) were also comparable (p=0.32). The AIT inlet significantly increased the capture of the coarse fraction compared with that collected by the Ph.Eur./USP induction port. Measures obtained using the AIM-pHRT apparatus were comparable with those obtained with the ACI-AIT.

The Maneuverable Atmospheric Probe (MAP), a Remotely Piloted Vehicle.

DTIC Science & Technology

1982-05-01

9 lb. MAP vehicle and major- components .................................... 10 2. Endevco Pitot tube airspeed indicator mounted below front...28 8. Cascaded PIXE impactors, housing cylinder and wing pod front end cup with aerosol inlet plastic tubing ........................... 30 9...turbulence sensors, a Pitot tube , two air temperature sensors, and a yaw gust probe. Located at each wing tip are sensors that contain encapsulated

Characterization of Total and Size-Fractionated Manganese Exposure by Work Area in a Shipbuilding Yard.

PubMed

Jeong, Jee Yeon; Park, Jong Su; Kim, Pan Gyi

2016-06-01

Shipbuilding involves intensive welding activities, and welders are exposed to a variety of metal fumes, including manganese, that may be associated with neurological impairments. This study aimed to characterize total and size-fractionated manganese exposure resulting from welding operations in shipbuilding work areas. In this study, we characterized manganese-containing particulates with an emphasis on total mass (n = 86, closed-face 37-mm cassette samplers) and particle size-selective mass concentrations (n = 86, 8-stage cascade impactor samplers), particle size distributions, and a comparison of exposure levels determined using personal cassette and impactor samplers. Our results suggest that 67.4% of all samples were above the current American Conference of Governmental Industrial Hygienists manganese threshold limit value of 100 μg/m(3) as inhalable mass. Furthermore, most of the particles containing manganese in the welding process were of the size of respirable particulates, and 90.7% of all samples exceeded the American Conference of Governmental Industrial Hygienists threshold limit value of 20 μg/m(3) for respirable manganese. The concentrations measured with the two sampler types (cassette: total mass; impactor: inhalable mass) were significantly correlated (r = 0.964, p < 0.001), but the total concentration obtained using cassette samplers was lower than the inhalable concentration of impactor samplers.

Aerosol Optical Properties of the Free Troposphere

DTIC Science & Technology

1991-12-16

will be made possible by using the specialized instrumentation developed at the University of Wyoming during the last year. le SUBIECT TEA~mS IS...investigators. Since most of the progress concerning the instrument development portion of the research was presented in the quarterly reports, this report...I iiii averages. lmpactor The cascade impactor is a PIXE Corporation five stage single orifice device. The equiva- lent aerodynamic cutoff diameters

Particle bounce in a personal cascade impactor: a field evaluation.

PubMed

Hinds, W C; Liu, W C; Froines, J R

1985-09-01

The collection characteristics of five types of substrates (collection surfaces) used in personal cascade impactors were evaluated for particle bounce in the laboratory with lead dioxide dust, and in the field with brass pouring fume and brass grinding dust. The substrates tested were uncoated stainless steel, silicon grease-coated stainless steel, oil-saturated Millipore membrane filter, oil-saturated Teflon membrane filter and oil-saturated sintered stainless steel. The use of coated and uncoated stainless steel plates to collect lead dioxide dust produced no difference in measured mass median diameter (MMD); however, with brass grinding dust, there was a 50% decrease in measured MMD when uncoated stainless steel substrates were used, as compared with coated stainless steel substrates. Oil-saturated Millipore membrane surfaces gave consistently lower MMDs than coated stainless steel surfaces. Coated and uncoated stainless steel gave similar MMDs when used to sample brass pouring fume. Oil-saturated Teflon membrane and oil-saturated sintered metal, surfaces for which the collection efficiency is presumed to be independent of the particle loading, gave MMDs similar to those measured for grease-coated stainless steel. The implications of these comparisons are discussed. It is concluded that bounce characteristics are strongly dependent on aerosol material and the suitability of collection surfaces needs to be determined by field evaluation.

Aerodynamic particle size analysis of aerosols from pressurized metered-dose inhalers: comparison of Andersen 8-stage cascade impactor, next generation pharmaceutical impactor, and model 3321 Aerodynamic Particle Sizer aerosol spectrometer.

PubMed

Mitchell, Jolyon P; Nagel, Mark W; Wiersema, Kimberly J; Doyle, Cathy C

2003-10-22

The purpose of this research was to compare three different methods for the aerodynamic assessment of (1) chloroflurocarbon (CFC)--fluticasone propionate (Flovent), (2) CFC-sodium cromoglycate (Intal), and (3) hydrofluoroalkane (HFA)--beclomethasone dipropionate (Qvar) delivered by pressurized metered dose inhaler. Particle size distributions were compared determining mass median aerodynamic diameter (MMAD), geometric standard deviation (GSD), and fine particle fraction <4.7 microm aerodynamic diameter (FPF(<4.7 microm)). Next Generation Pharmaceutical Impactor (NGI)-size distributions for Flovent comprised finer particles than determined by Andersen 8-stage impactor (ACI) (MMAD = 2.0 +/- 0.05 micro m [NGI]; 2.8 +/- 0.07 microm [ACI]); however, FPF(<4.7 microm) by both impactors was in the narrow range 88% to 93%. Size distribution agreement for Intal was better (MMAD = 4.3 +/- 0.19 microm (NGI), 4.2 +/- 0.13 microm (ACI), with FPF(<4.7 microm) ranging from 52% to 60%. The Aerodynamic Particle Sizer (APS) undersized aerosols produced with either formulation (MMAD = 1.8 +/- 0.07 micro m and 3.2 +/- 0.02 micro m for Flovent and Intal, respectively), but values of FPF(<4.7 microm)from the single-stage impactor (SSI) located at the inlet to the APS (82.9% +/- 2.1% [Flovent], 46.4% +/- 2.4% [Intal]) were fairly close to corresponding data from the multi-stage impactors. APS-measured size distributions for Qvar (MMAD = 1.0 +/- 0.03 micro m; FPF(<4.7 micro m)= 96.4% +/- 2.5%), were in fair agreement with both NGI (MMAD = 0.9 +/- 0.03 micro m; FPF(<4.7 microm)= 96.7% +/- 0.7%), and ACI (MMAD = 1.2 +/- 0.02 microm, FPF(<4.7 microm)= 98% +/- 0.5%), but FPF(<4.7 microm) from the SSI (67.1% +/- 4.1%) was lower than expected, based on equivalent data obtained by the other techniques. Particle bounce, incomplete evaporation of volatile constituents and the presence of surfactant particles are factors that may be responsible for discrepancies between the techniques.

Size-selective pulmonary dose indices for metal-working fluid aerosols in machining and grinding operations in the automobile manufacturing industry.

PubMed

Woskie, S R; Smith, T J; Hallock, M F; Hammond, S K; Rosenthal, F; Eisen, E A; Kriebel, D; Greaves, I A

1994-01-01

The current metal-working fluid exposures at three locations that manufacture automotive parts were assessed in conjunction with epidemiological studies of the mortality and respiratory morbidity experiences of workers at these plants. A rationale is presented for selecting and characterizing epidemiologic exposure groups in this environment. More than 475 full-shift personal aerosol samples were taken using a two-stage personal cascade impactor with median size cut-offs of 9.8 microns and 3.5 microns, plus a backup filter. For a sample of 403 workers exposed to aerosols of machining or grinding fluids, the mean total exposure was 706 micrograms/m3 (standard error (SE) = 21 micrograms/m3). Among 72 assemblers unexposed to machining fluids, the mean total exposure was 187 +/- 10 (SE) micrograms/m3. An analysis of variance model identified factors significantly associated with exposure level and permitted estimates of exposure for workers in the unsampled machine type/metal-working fluid groups. Comparison of the results obtained from personal impactor samples with predictions from an aerosol-deposition model for the human respiratory tract showed high correlation. However, the amount collected on the impactor stage underestimates extrathoracic deposition and overestimates tracheobronchial and alveolar deposition, as calculated by the deposition model. When both the impactor concentration and the deposition-model concentration were used to estimate cumulative thoracic concentrations for the worklives of a subset of auto workers, there was no significant difference in the rank order of the subjects' cumulative concentration. However, the cumulative impactor concentration values were significantly higher than the cumulative deposition-model concentration values for the subjects.

Alpha spectrometric characterization of process-related particle size distributions from active particle sampling at the Los Alamos National Laboratory uranium foundry

NASA Astrophysics Data System (ADS)

Plionis, A. A.; Peterson, D. S.; Tandon, L.; LaMont, S. P.

2010-03-01

Uranium particles within the respirable size range pose a significant hazard to the health and safety of workers. Significant differences in the deposition and incorporation patterns of aerosols within the respirable range can be identified and integrated into sophisticated health physics models. Data characterizing the uranium particle size distribution resulting from specific foundry-related processes are needed. Using personal air sampling cascade impactors, particles collected from several foundry processes were sorted by activity median aerodynamic diameter onto various Marple substrates. After an initial gravimetric assessment of each impactor stage, the substrates were analyzed by alpha spectrometry to determine the uranium content of each stage. Alpha spectrometry provides rapid non-distructive isotopic data that can distinguish process uranium from natural sources and the degree of uranium contribution to the total accumulated particle load. In addition, the particle size bins utilized by the impactors provide adequate resolution to determine if a process particle size distribution is: lognormal, bimodal, or trimodal. Data on process uranium particle size values and distributions facilitate the development of more sophisticated and accurate models for internal dosimetry, resulting in an improved understanding of foundry worker health and safety.

An analytical method coupling accelerated solvent extraction and HPLC-fluorescence for the quantification of particle-bound PAHs in indoor air sampled with a 3-stages cascade impactor.

PubMed

Liaud, Céline; Millet, Maurice; Le Calvé, Stéphane

2015-01-01

Most of Polycyclic Aromatic Hydrocarbons (PAHs) are associated to airborne particles and their health impact depends on the particle size where they are bound. This work aims to develop a high sensitive analytical technique to quantify particulate PAHs sampled with a 3-stages cascade impactor in order to derive simultaneously their individual concentration in PM1, PM2.5 and PM10. Three key steps of the method were evaluated separately in order to avoid any PAHs loss during the global sample preparation procedure: (1) the accelerated solvent extraction of PAHs from the filter; (2) the primary concentration of the extract until 1 mL by means of a rotary evaporator at 45°C and 220 mbar and (3) the final concentration of the pre-concentrated extract to about 100-150 µL under a gentle nitrogen stream. Each recovery experiment was realized in triplicates. All these steps evaluated independently show that the overall PAHs loss, even for those with a low molecular weight, should not exceed more than a few percent. Extracts were then analyzed by using a HPLC coupled to fluorescence and Diode Array Detectors with the external standard method. The resulting calibration curves containing between 9 and 12 points were plotted in the concentration range of 0.05-45 µg L(-1) for most of the 16 US-EPA priority PAHs and were fully linear (R(2)>0.999). Limits Of Quantification were in the range 0.05-0.47 µg L(-1) corresponding to 0.75-7.05 pg m(-3) for 20 m(3) of pumped air. Finally, taking into account the average PAHs concentrations previously reported in typical European indoor environments, and considering the use of a 3-stages cascade impactor to collect simultaneously PM>10 µm, 2.5 µm

Dissolution of fine particle fraction from truncated Anderson cascade impactor with an enhancer cell.

PubMed

Tay, Justin Yong Soon; Liew, Celine Valeria; Heng, Paul Wan Sia

2018-04-22

Dissolution testing for inhalers were previously conducted either on unfractionated drug-carrier powders or drug of specific aerodynamic particle size. In this study, the collection of the full fine particle fraction (FPF) was attempted on a single stage. Capsules containing 30 mg of 2% salbutamol sulfate (SS) was tested to have a FPF of 9 ± 1% using the full set of Andersen cascade impactor (ACI) and a modified Rotahaler® capable of achieving 4.0 kPa pressure drop at 60 L/min air flow rate. A truncated ACI comprising the USP throat, pre-separator, stage 0, stage 4, stage F, polytetrafluoroethylene funnel (TF) and small collection plate (sCP) was found to be capable of achieving a FPF of 9% collected on TF and sCP. An adhesive tape was used to collect the FPF from the TF and sCP and held in place by an enhancer cell in a 200 mL round bottom vessel containing 50 mL Gamble's solution with 0.2 v/v, % Tween 80. Dissolution testing of SS and Seretide® showed burst release of SS and salmeterol while sustained release of fluticasone. This study demonstrated a reproducible method which may be used for evaluation of the full FPF of orally inhaled products. Copyright © 2018 Elsevier B.V. All rights reserved.

Zirconium isotope constraints on the composition of Theia and current Moon-forming theories

NASA Astrophysics Data System (ADS)

Akram, W.; Schönbächler, M.

2016-09-01

The giant impact theory is the most widely recognized formation scenario of the Earth's Moon. Giant impact models based on dynamical simulations predict that the Moon acquired a significant amount of impactor (Theia) material, which is challenging to reconcile with geochemical data for O, Si, Cr, Ti and W isotopes in the Earth and Moon. Three new giant impact scenarios have been proposed to account for this discrepancy - hit-and-run impact, impact with a fast-spinning protoEarth and massive impactors - each one reducing the proportion of the impactor in the Moon compared to the original canonical giant impact model. The validity of each theory and their different dynamical varieties are evaluated here using an integrated approach that considers new high-precision Zr isotope measurements of lunar rocks, and quantitative geochemical modelling of the isotopic composition of the impactor Theia. All analysed lunar samples (whole-rock, ilmenite and pyroxene separates) display identical Zr isotope compositions to that of the Earth within the uncertainty of 13 ppm for 96Zr/90Zr (2σ weighted average). This 13 ppm upper limit is used to infer the most extreme isotopic composition that Theia could have possessed, relative to the Earth, for each of the proposed giant impact theories. The calculated Theian composition is compared with the Zr isotope compositions of different solar system materials in order to constrain the source region of the impactor. As a first order approximation, we show that all considered models (including the canonical) are plausible, alleviating the initial requirement for the new giant impact models. Albeit, the canonical and hit-and-run models are the most restrictive, suggesting that the impactor originated from a region close to the Earth. The fast-spinning protoEarth and massive impactor models are more relaxed and increase the allowed impactor distance from the Earth. Similar calculations carried out for O, Cr, Ti and Si isotope data support these conclusions but exclude a CI- and enstatite chondrite-like composition for Theia. Thus, the impactor Theia most likely had a Zr isotope composition close to that of the Earth, and this suggests that a large part of the inner solar system (or accretion region of the Earth, Theia and enstatite chondrites) had a uniform Zr isotope composition.

Dissolution of aerosol particles collected from nuclear facility plutonium production process

DOE PAGES

Xu, Ning; Martinez, Alexander; Schappert, Michael Francis; ...

2015-08-14

Here, a simple, robust analytical chemistry method has been developed to dissolve plutonium containing particles in a complex matrix. The aerosol particles collected on Marple cascade impactor substrates were shown to be dissolved completely with an acid mixture of 12 M HNO 3 and 0.1 M HF. A pressurized closed vessel acid digestion technique was utilized to heat the samples at 130 °C for 16 h to facilitate the digestion. The dissolution efficiency for plutonium particles was 99 %. The resulting particle digestate solution was suitable for trace elemental analysis and isotope composition determination, as well as radiochemistry measurements.

Inhalation and Ingestion Intakes with Associated Dose Estimates for Level II and Level III Personnel Using Capstone Study Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szrom, Fran; Falo, Gerald A.; Lodde, Gordon M.

2009-03-01

Depleted uranium (DU) intake rates and subsequent dose rates were estimated for personnel entering armored combat vehicles perforated with DU penetrators (level II and level III personnel) using data generated during the Capstone Depleted Uranium (DU) Aerosol Study. Inhalation intake rates and associated dose rates were estimated from cascade impactors worn by sample recovery personnel and from cascade impactors that served as area monitors. Ingestion intake rates and associated dose rates were estimated from cotton gloves worn by sample recovery personnel and from wipe test samples from the interior of vehicles perforated with large caliber DU munitions. The mean DUmore » inhalation intake rate for level II personnel ranged from 0.447 mg h-1 based on breathing zone monitor data (in and around a perforated vehicle) to 14.5 mg h-1 based on area monitor data (in a perforated vehicle). The mean DU ingestion intake rate for level II ranged from 4.8 mg h-1 to 38.9 mg h-1 based on the wipe test data including surface to glove transfer factors derived from the Capstone data. Based on glove contamination data, the mean DU ingestion intake rates for level II and level III personnel were 10.6 mg h-1 was and 1.78 mg h-1, respectively. Effective dose rates and peak kidney uranium concentration rates were calculated based on the intake rates. The peak kidney uranium concentration rate cannot be multiplied by the total exposure duration when multiple intakes occur because uranium will clear from the kidney between the exposures.« less

Elemental composition and size distribution of particulates in Cleveland, Ohio

NASA Technical Reports Server (NTRS)

King, R. B.; Fordyce, J. S.; Neustadter, H. E.; Leibecki, H. F.

1975-01-01

Measurements were made of the elemental particle size distribution at five contrasting urban environments with different source-type distributions in Cleveland, Ohio. Air quality conditions ranged from normal to air pollution alert levels. A parallel network of high-volume cascade impactors (5-state) were used for simultaneous sampling on glass fiber surfaces for mass determinations and on Whatman-41 surfaces for elemental analysis by neutron activation for 25 elements. The elemental data are assessed in terms of distribution functions and interrelationships and are compared between locations as a function of resultant wind direction in an attempt to relate the findings to sources.

Elemental composition and size distribution of particulates in Cleveland, Ohio

NASA Technical Reports Server (NTRS)

Leibecki, H. F.; King, R. B.; Fordyce, J. S.; Neustadter, H. E.

1975-01-01

Measurements have been made of the elemental particle size distribution at five contrasting urban environments with different source-type distributions in Cleveland, Ohio. Air quality conditions ranged from normal to air pollution alert levels. A parallel network of high-volume cascade impactors (5-stage) were used for simultaneous sampling on glass fiber surfaces for mass determinations and on Whatman-41 surfaces for elemental analysis by neutron activation for 25 elements. The elemental data are assessed in terms of distribution functions and interrelationships and are compared between locations as a function of resultant wind direction in an attempt to relate the findings to sources.

Rapid Analysis of the Size Distribution of Metal-Containing Aerosol

PubMed Central

Park, Jae Hong; Mudunkotuwa, Imali A.; Crawford, Kathryn J.; Anthony, T. Renée; Grassian, Vicki H.; Peters, Thomas M.

2017-01-01

Conventional methods to measure the metallic content of particles by size are time consuming and expensive, requiring collection of particles with a cascade impactor and subsequent metals analysis by inductively coupled plasma mass spectrometry (ICP-MS). In this work, we describe a rapid way to measure the size distribution of metal-containing particles from 10 nm to 20 μm, using a nano micro-orifice uniform-deposit impactor (nano-MOUDI) to size-selective and collect particles that are then analyzed with a field portable X-ray fluorescence (FP-XRF) to determine metal composition and concentration. The nano-MOUDI was used to sample a stainless-steel aerosol produced by a spark discharge system. The particle-laden substrates were then analyzed directly with FP-XRF and then with ICP-MS. Results from FP-XRF were linearly correlated with results from ICP-MS (R2 = 0.91 for Fe and R2 = 0.84 for Cr). Although the FP-XRF was unable to detect Fe particles at mass per substrate loadings less than 2.5 μg effectively, it produced results similar to those using the ICP-MS at a mass per substrate loading greater than 2.5 μg. PMID:28871214

Emission of bacterial bioaerosols from a composting facility in Maharashtra, India.

PubMed

Pahari, Arnab Kumar; Dasgupta, Debdeep; Patil, Rashmi S; Mukherji, Suparna

2016-07-01

This study was undertaken to quantify and characterize size-segregated bacterial bioaerosols both on-site and off-site of a waste treatment facility (WTF) in Maharashtra employing windrow composting. Viable bacterial bioaerosols on nutrient agar (NA) and actinomycetes isolation agar (AIA) were quantified after sampling using Anderson-six stage impactor. Viable bacterial bioaerosols were identified based on 16S rDNA sequencing. Approximately, 16-34% of the total viable bacteria collected at the WTF were in the size range 0.65-2.1μm that can penetrate deep into the respiratory tract and also represents bacteria present in free form. Thus, 66-84% of bacterial bioaerosols were associated with coarse airborne particles greater than 2.1μm. A total of 24 bacterial species were isolated and characterized through gram staining. Among these 25% were gram negative and 75% were gram positive. The predominant bacterial genera were Bacillus, Streptococcus, Staphylococcus, Acinetobacter and Kocuria. The mean on-site concentration of total viable bacteria on NA and AIA and airborne particles (PM2.5 and PM10) were higher than the corresponding off-site values. The mean on-site concentration of viable bacteria on NA and AIA were in the range of 3.8×10(3) to 5.4×10(4)CFU/m(3) and 9.8×10(3) to 1.2×10(5)CFU/m(3), respectively, during activity period. Good correlation (R(2)=0.999) was observed between total bioaerosols and aerosols (PM10) collected using Anderson impactor and High volume sampler, respectively. Sampling size segregated aerosols using the Siotus personal cascade impactor indicated higher association of bacteria with the coarse fraction (greater than 2.5μm). Copyright © 2016 Elsevier Ltd. All rights reserved.

Physicochemical Characterization of Capstone Depleted Uranium Aerosols II: Particle Size Distributions as a Function of Time

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Yung-Sung; Kenoyer, Judson L.; Guilmette, Raymond A.

2009-03-01

The Capstone Depleted Uranium (DU) Aerosol Study, which generated and characterized aerosols containing depleted uranium from perforation of armored vehicles with large-caliber DU penetrators, incorporated a sampling protocol to evaluated particle size distributions. Aerosol particle size distribution is an important parameter that influences aerosol transport and deposition processes as well as the dosimetry of the inhaled particles. These aerosols were collected on cascade impactor substrates using a pre-established time sequence following the firing event to analyze the uranium concentration and particle size of the aerosols as a function of time. The impactor substrates were analyzed using beta spectrometry, and themore » derived uranium content of each served as input to the evaluation of particle size distributions. Activity median aerodynamic diameters (AMADs) of the particle size distributions were evaluated using unimodal and bimodal models. The particle size data from the impactor measurements was quite variable. Most size distributions measured in the test based on activity had bimodal size distributions with a small particle size mode in the range of between 0.2 and 1.2 um and a large size mode between 2 and 15 um. In general, the evolution of particle size over time showed an overall decrease of average particle size from AMADs of 5 to 10 um shortly after perforation to around 1 um at the end of the 2-hr sampling period. The AMADs generally decreased over time because of settling. Additionally, the median diameter of the larger size mode decreased with time. These results were used to estimate the dosimetry of inhaled DU particles.« less

[Polycyclic aromatic hydrocarbons and soluble organic fraction in fine particles from solid fraction of biodiesel exhaust fumes].

PubMed

Szewczyńska, Małgorzata; Pośniak, Małgorzata

2012-01-01

This paper presents the results of investigations into the distribution of fine particles in the biodiesel exhaust fumes (bio-DEP), as well as into the content of polycyclic aromatic hydrocarbons (PAHs) and soluble organic fraction (SOF) in the study fractions. Samples of biodiesel B20 and B40 exhaust combustion fumes were generated at the model station composed of a diesel engine from Diesel TDI 2007 Volkswagen. Sioutas personal cascade impactor (SPCI) with Teflon filters and low-pressure impactor ELIPI (Dekati Low Pressure Impactor) were used for sampling diesel exhaust fine particles. The analysis of PAHs adsorbed on particulate fractions was performed by high performance liquid chromatography with fluorescence detection (HPLC/FL). For the determination of dry residue soluble organic fraction of biodiesel exhaust particles the gravimetric method was used. The combustion exhaust fumes of 100% ON contained mainly naphthalene, acenaphthalene, fluorene, phenanthrene, fluoranthene, pyrene, benzo(a)anthracene and chrysene, whilst the exhaust of B40-single PAHs of 4 and 5 rings, such as chrysene, benzo(k)fluoranthene, dibenzo (ah)anthracene and benzo(ghi)perylene. The total content of PAHs in diesel exhaust particles averaged 910 ng/m3 for 100% ON and 340 ng/m3 for B40. The concentrations of benzo(a)antarcene were at the levels of 310 ng/m3 (100% ON) and 90 ng/m3 (B40). The investigations indicated that a fraction < 025 microm represents the main component of diesel exhaust particles, regardless of the used fuel. Bioester B 100 commonly added to diesel fuel (ON) causes a reduction of the total particulates emission and thus reduces the amount of toxic substances adsorbed on their surface.

Time-Resolved Molecular Characterization of Limonene/Ozone Aerosol using High-Resolution Electrospray Ionization Mass Spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bateman, Adam P.; Nizkorodov, Serguei; Laskin, Julia

2009-09-09

Molecular composition of limonene/O3 secondary organic aerosol (SOA) was investigated using high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) as a function of reaction time. SOA was generated by ozonation of D-limonene in a reaction chamber and sampled at different time intervals using a cascade impactor. The SOA samples were extracted into acetonitrile and analyzed using a HR-ESI-MS instrument with a resolving power of 100,000 (m/Δm). The resulting mass spectra provided detailed information about the extent of oxidation inferred from the O:C ratios, double bond equivalency (DBE) factors, and aromaticity indexes (AI) in hundreds of identified individual SOA species.

Ambient measurements of biological aerosol particles near Killarney, Ireland: a comparison between real-time fluorescence and microscopy techniques

NASA Astrophysics Data System (ADS)

Healy, D. A.; Huffman, J. A.; O'Connor, D. J.; Pöhlker, C.; Pöschl, U.; Sodeau, J. R.

2014-08-01

Primary biological aerosol particles (PBAPs) can contribute significantly to the coarse particle burden in many environments. PBAPs can thus influence climate and precipitation systems as cloud nuclei and can spread disease to humans, animals, and plants. Measurement data and techniques for PBAPs in natural environments at high time- and size resolution are, however, sparse, and so large uncertainties remain in the role that biological particles play in the Earth system. In this study two commercial real-time fluorescence particle sensors and a Sporewatch single-stage particle impactor were operated continuously from 2 August to 2 September 2010 at a rural sampling location in Killarney National Park in southwestern Ireland. A cascade impactor was operated periodically to collect size-resolved particles during exemplary periods. Here we report the first ambient comparison of a waveband integrated bioaerosol sensor (WIBS-4) with a ultraviolet aerodynamic particle sizer (UV-APS) and also compare these real-time fluorescence techniques with results of fluorescence and optical microscopy of impacted samples. Both real-time instruments showed qualitatively similar behavior, with increased fluorescent bioparticle concentrations at night, when relative humidity was highest and temperature was lowest. The fluorescent particle number from the FL3 channel of the WIBS-4 and from the UV-APS were strongly correlated and dominated by a 3 μm mode in the particle size distribution. The WIBS FL2 channel exhibited particle modes at approx. 1 and 3 μm, and each was correlated with the concentration of fungal spores commonly observed in air samples collected at the site (ascospores, basidiospores, Ganoderma spp.). The WIBS FL1 channel exhibited variable multimodal distributions turning into a broad featureless single mode after averaging, and exhibited poor correlation with fungal spore concentrations, which may be due to the detection of bacterial and non-biological fluorescent particles. Cladosporium spp., which are among the most abundant fungal spores in many terrestrial environments, were not correlated with any of the real-time fluorescence channels, suggesting that the real-time fluorescence instruments are relatively insensitive to PBAP classes with dark, highly absorptive cell walls. Fluorescence microscopy images of cascade impactor plates showed large numbers of coarse-mode particles consistent with the morphology and weak fluorescence expected of sea salt. Some of these particles were attached to biological cells, suggesting that a marine source influenced the PBAPs observed at the site and that the ocean may be an important contributor to PBAP loadings in coastal environments.

Ambient measurements of biological aerosol particles near Killarney, Ireland: a comparison between real-time fluorescence and microscopy techniques

NASA Astrophysics Data System (ADS)

Healy, D. A.; Huffman, J. A.; O'Connor, D. J.; Pöhlker, C.; Pöschl, U.; Sodeau, J. R.

2014-02-01

Primary biological aerosol particles (PBAP) can contribute significantly to the coarse particle burden in many environments, may thus influence climate and precipitation systems as cloud nuclei, and can spread disease to humans, animals, and plants. Measurements of PBAP in natural environments taken at high time- and size- resolution are, however, sparse and so large uncertainties remain in the role that biological particles play in the Earth system. In this study two commercial real-time fluorescence particle sensors and a Sporewatch single-stage particle impactor were operated continuously from 2 August to 2 September 2010 at a rural sampling location in Killarney National Park in south western Ireland. A cascade impactor was operated periodically to collect size-resolved particles during exemplary periods. Here we report the first ambient comparison of the waveband integrated bioaerosol sensor (WIBS-4) with the ultraviolet aerodynamic particle sizer (UV-APS) and also compare these real-time fluorescence techniques with results of fluorescence and optical microscopy of impacted samples. Both real-time instruments showed qualitatively similar behaviour, with increased fluorescent bioparticle concentrations at night when relative humidity was highest and temperature was lowest. The fluorescent particle number from the FL3 channel of the WIBS-4 and from the UV-APS were strongly correlated and dominated by a 3 μm mode in the particle size distribution. The WIBS FL2 channel exhibited particle modes at approx. 1 and 3 μm, and each were correlated with the concentration of fungal spores commonly observed in air samples collected at the site (ascospores, basidiospores, Ganoderma spp.). The WIBS FL1 channel exhibited variable multi-modal distributions turning into a broad featureless single mode after averaging and exhibited poor correlation with fungal spore concentrations, which may be due to the detection of bacterial and non-biological fluorescent particles. Cladosporium spp., which are among the most abundant fungal spores in many terrestrial environments, were not correlated with any of the real-time fluorescence channels, suggesting that the real-time fluorescence instruments are insensitive to PBAP classes with dark, highly absorptive cell walls. Fluorescence microscopy images of cascade impactor plates showed large numbers of coarse mode particles consistent with the morphology and weak fluorescence expected of sea salt. Some of these particles were attached to biological cells, suggesting that a marine source influenced the PBAP observed at the site and that the ocean may be an important contributor to PBAP loadings in coastal environments.

Sampling and data handling methods for inhalable particulate sampling. Final report nov 78-dec 80

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, W.B.; Cushing, K.M.; Johnson, J.W.

1982-05-01

The report reviews the objectives of a research program on sampling and measuring particles in the inhalable particulate (IP) size range in emissions from stationary sources, and describes methods and equipment required. A computer technique was developed to analyze data on particle-size distributions of samples taken with cascade impactors from industrial process streams. Research in sampling systems for IP matter included concepts for maintaining isokinetic sampling conditions, necessary for representative sampling of the larger particles, while flowrates in the particle-sizing device were constant. Laboratory studies were conducted to develop suitable IP sampling systems with overall cut diameters of 15 micrometersmore » and conforming to a specified collection efficiency curve. Collection efficiencies were similarly measured for a horizontal elutriator. Design parameters were calculated for horizontal elutriators to be used with impactors, the EPA SASS train, and the EPA FAS train. Two cyclone systems were designed and evaluated. Tests on an Andersen Size Selective Inlet, a 15-micrometer precollector for high-volume samplers, showed its performance to be with the proposed limits for IP samplers. A stack sampling system was designed in which the aerosol is diluted in flow patterns and with mixing times simulating those in stack plumes.« less

Laboratory Study Comparing Pharmacopeial Testing of Nebulizers with Evaluation Based on Nephele Mixing Inlet Methodology.

PubMed

Svensson, Mårten; Berg, Elna; Mitchell, Jolyon; Sandell, Dennis

2018-02-01

Determination of fine droplet dose with preparations for nebulization, currently deemed to be the metric most indicative of lung deposition and thus in vivo responses, involves combining two procedures following practice as described in the United States Pharmacopeia and the European Pharmacopeia. Delivered dose (DD) is established by simulating tidal breathing at the nebulizer, collecting the medication on a filter downstream of the nebulizer mouthpiece/facemask. Fine droplet fraction (FDF

Safety assessment characteristics of pedestrian legform impactors in vehicle-front impact tests.

PubMed

Matsui, Yasuhiro

2014-12-01

This study investigated the characteristics of safety assessment results of front-area vehicle impact tests carried out using the Transport Research Laboratory (TRL) legform impactor and a flexible legform impactor (FLEX legform impactor). Different types of vehicles (sedan, sport utility vehicle, high-roof K-car, and light cargo van) were examined. The impact locations in the study were the center of the bumper and an extremely stiff structure of the bumper (i.e., in front of the side member) of each tested vehicle. The measured injury criteria were normalized by injury assessment reference values of each legform impactor. The test results for center and side-member impacts indicated that there were no significant differences in ligament injury assessments derived from the normalized knee ligament injury measures between the TRL legform impactor and the FLEX legform impactor. Evaluations made using the TRL legform impactor and the FLEX legform impactor are thus similar in the vehicle safety investigation for knee ligament injury. Vehicle-center impact test results revealed that the tibia fracture assessments derived from the normalized tibia fracture measures did not significantly differ between the TRL legform impactor and the FLEX legform impactor. However, for an impact against an extremely stiff structure, there was a difference in the tibia fracture assessment between the FLEX legform impactor and the TRL legform impactor owing to their different sensor types. Copyright © 2014 Elsevier Ltd. All rights reserved.

Explosive plane-wave lens

DOEpatents

Marsh, Stanley P.

1988-01-01

An explosive plane-wave air lens which enables a spherical wave form to be converted to a planar wave without the need to specially machine or shape explosive materials is described. A disc-shaped impactor having a greater thickness at its center than around its periphery is used to convert the spherical wave into a plane wave. When the wave reaches the impactor, the center of the impactor moves first because the spherical wave reaches the center of the impactor first. The wave strikes the impactor later in time as one moves radially along the impactor. Because the impactor is thinner as one moves radially outward, the velocity of the impactor is greater at the periphery than at the center. An acceptor explosive is positioned so that the impactor strikes the acceptor simultaneously. Consequently, a plane detonation wave is propagated through the acceptor explosive.

Explosive plane-wave lens

DOEpatents

Marsh, S.P.

1988-03-08

An explosive plane-wave air lens which enables a spherical wave form to be converted to a planar wave without the need to specially machine or shape explosive materials is described. A disc-shaped impactor having a greater thickness at its center than around its periphery is used to convert the spherical wave into a plane wave. When the wave reaches the impactor, the center of the impactor moves first because the spherical wave reaches the center of the impactor first. The wave strikes the impactor later in time as one moves radially along the impactor. Because the impactor is thinner as one moves radially outward, the velocity of the impactor is greater at the periphery than at the center. An acceptor explosive is positioned so that the impactor strikes the acceptor simultaneously. Consequently, a plane detonation wave is propagated through the acceptor explosive. 4 figs.

On the Impact Origin of Phobos and Deimos. III. Resulting Composition from Different Impactors

NASA Astrophysics Data System (ADS)

Pignatale, Francesco C.; Charnoz, Sébastien; Rosenblatt, Pascal; Hyodo, Ryuki; Nakamura, Tomoki; Genda, Hidenori

2018-02-01

The origin of Phobos and Deimos in a giant impact-generated disk is gaining larger attention. Although this scenario has been the subject of many studies, an evaluation of the chemical composition of the Mars’s moons in this framework is missing. The chemical composition of Phobos and Deimos is unconstrained. The large uncertainties about the origin of the mid-infrared features; the lack of absorption bands in the visible and near-infrared spectra; and the effects of secondary processes on the moons’ surfaces make the determination of their composition very difficult using remote sensing data. Simulations suggest a formation of a disk made of gas and melt with their composition linked to the nature of the impactor and Mars. Using thermodynamic equilibrium, we investigate the composition of dust (condensates from gas) and solids (from a cooling melt) that result from different types of Mars impactors (Mars-, CI-, CV-, EH-, and comet-like). Our calculations show a wide range of possible chemical compositions and noticeable differences between dust and solids, depending on the considered impactors. Assuming that Phobos and Deimos resulted from the accretion and mixing of dust and solids, we find that the derived assemblage (dust-rich in metallic iron, sulfides and/or carbon, and quenched solids rich in silicates) can be compatible with the observations. The JAXA’s Martian Moons eXploration (MMX) mission will investigate the physical and chemical properties of Phobos and Deimos, especially sampling from Phobos, before returning to Earth. Our results could be then used to disentangle the origin and chemical composition of the pristine body that hit Mars and suggest guidelines for helping in the analysis of the returned samples.

Virtual impactor

DOEpatents

Yeh, Hsu-Chi; Chen, Bean T.; Cheng, Yung-Sung; Newton, George J.

1988-08-30

A virtual impactor having improved efficiency and low wall losses in which a core of clean air is inserted into the aerosol flow while aerosol flow is maintained adjacent inner wall surfaces of the focusing portion of the impactor. The flow rate of the core and the length of the throat of the impactor's collection probe, as well as the dimensional relationships of other components of the impactor adjacent the separation region of the impactor, are selected to optimize separation efficiency.

Explosive plane-wave lens

DOEpatents

Marsh, S.P.

1987-03-12

An explosive plane-wave air lens which enables a spherical wave form to be converted to a planar wave without the need to specially machine or shape explosive materials is described. A disc-shaped impactor having a greater thickness at its center than around its periphery is used to convert the spherical wave into a plane wave. When the wave reaches the impactor, the center of the impactor moves first because the spherical wave reaches the center of the impactor first. The wave strikes the impactor later in time as one moves radially along the impactor. Because the impactor is thinner as one moves radially outward, the velocity of the impactor is greater at the periphery than at the center. An acceptor explosive is positioned so that the impactor strikes the acceptor simultaneously. Consequently, a plane detonation wave is propagated through the acceptor explosive. 3 figs., 3 tabs.

Factors Associated with PMTCT Cascade Completion in Four African Countries.

PubMed

Dionne-Odom, Jodie; Welty, Thomas K; Westfall, Andrew O; Chi, Benjamin H; Ekouevi, Didier Koumavi; Kasaro, Margaret; Tih, Pius M; Tita, Alan T N

2016-01-01

Background. Many countries are working to reduce or eliminate mother-to-child transmission (MTCT) of HIV. Prevention efforts have been conceptualized as steps in a cascade but cascade completion rates during and after pregnancy are low. Methods. A cross-sectional survey was performed across 26 communities in Cameroon, Cote d'Ivoire, South Africa, and Zambia. Women who reported a pregnancy within two years were enrolled. Participant responses were used to construct the PMTCT cascade with all of the following steps required for completion: at least one antenatal visit, HIV testing performed, HIV testing result received, initiation of maternal prophylaxis, and initiation of infant prophylaxis. Factors associated with cascade completion were identified using multivariable logistic regression modeling. Results. Of 976 HIV-infected women, only 355 (36.4%) completed the PMTCT cascade. Although most women (69.2%) did not know their partner's HIV status; awareness of partner HIV status was associated with cascade completion (aOR 1.4, 95% CI 1.01-2.0). Completion was also associated with receiving an HIV diagnosis prior to pregnancy compared with HIV diagnosis during or after pregnancy (aOR 14.1, 95% CI 5.2-38.6). Conclusions. Pregnant women with HIV infection in Africa who were aware of their partner's HIV status and who were diagnosed with HIV before pregnancy were more likely to complete the PMTCT cascade.

Factors Associated with PMTCT Cascade Completion in Four African Countries

PubMed Central

Welty, Thomas K.; Westfall, Andrew O.; Chi, Benjamin H.; Ekouevi, Didier Koumavi; Tih, Pius M.; Tita, Alan T. N.

2016-01-01

Background. Many countries are working to reduce or eliminate mother-to-child transmission (MTCT) of HIV. Prevention efforts have been conceptualized as steps in a cascade but cascade completion rates during and after pregnancy are low. Methods. A cross-sectional survey was performed across 26 communities in Cameroon, Cote d'Ivoire, South Africa, and Zambia. Women who reported a pregnancy within two years were enrolled. Participant responses were used to construct the PMTCT cascade with all of the following steps required for completion: at least one antenatal visit, HIV testing performed, HIV testing result received, initiation of maternal prophylaxis, and initiation of infant prophylaxis. Factors associated with cascade completion were identified using multivariable logistic regression modeling. Results. Of 976 HIV-infected women, only 355 (36.4%) completed the PMTCT cascade. Although most women (69.2%) did not know their partner's HIV status; awareness of partner HIV status was associated with cascade completion (aOR 1.4, 95% CI 1.01–2.0). Completion was also associated with receiving an HIV diagnosis prior to pregnancy compared with HIV diagnosis during or after pregnancy (aOR 14.1, 95% CI 5.2–38.6). Conclusions. Pregnant women with HIV infection in Africa who were aware of their partner's HIV status and who were diagnosed with HIV before pregnancy were more likely to complete the PMTCT cascade. PMID:27872760

Virtual impactor

DOEpatents

Yeh, H.C.; Chen, B.T.; Cheng, Y.S.; Newton, G.J.

1988-08-30

A virtual impactor is described having improved efficiency and low wall losses in which a core of clean air is inserted into the aerosol flow while aerosol flow is maintained adjacent to the inner wall surfaces of the focusing portion of the impactor. The flow rate of the core and the length of the throat of the impactor's collection probe, as well as the dimensional relationships of other components of the impactor adjacent the separation region of the impactor, are selected to optimize separation efficiency. 4 figs.

Impactor core disruption by high-energy planetary collisions

NASA Astrophysics Data System (ADS)

Landeau, M.; Phillips, D.; Deguen, R.; Neufeld, J.; Dalziel, S.; Olson, P.

2017-12-01

Understanding the fate of impactor cores during large planetary collisions is key for predicting metal-silicate equilibration during Earth's accretion. Accretion models and geochemical observations indicate that much of Earth's mass accreted through high-energy impacts between planetary embryos already differentiated into a metallic core and a silicate mantle. Previous studies on core formation assume that the metallic core of the impactor is left intact by the impact, but it mixes with silicates during the post-impact fall in the magma ocean. Recent impact simulations, however, suggest that the impact cratering process induces significant core disruption and metal-silicate mixing. Unlike existing impact simulations, experiments can produce turbulence, a key ingredient to investigate disruption of the impactor core. Here we use laboratory experiments where a volume of salt solution (representing the impactor core) vertically impacts a pool of water (representing the magma ocean) to quantify impact-induced mixing between the impactor and the target as a function of impact velocity, impactor size and density difference. We find that the ratio between the impactor inertia and its weight controls mixing. Extrapolated to planetary accretion, our results suggest that the impact process induces no significant mixing for impactors of comparable size as the protoplanet whereas the impactor core is highly disrupted by impacts involving impactors much smaller than the protoplanet.

Detailed mass size distributions of atmospheric aerosol species in the Negev desert, Israel, during ARACHNE-96

NASA Astrophysics Data System (ADS)

Maenhaut, Willy; Ptasinski, Jacek; Cafmeyer, Jan

1999-04-01

As part of the 1996 summer intensive of the Aerosol, RAdiation and CHemistry Experiment (ARACHNE-96), the mass size distribution of various airborne particulate elements was studied at a remote site in the Negev Desert, Israel. Aerosol collections were made with 8-stage PIXE International cascade impactors (PCIs) and 12-stage small deposit area low pressure impactors (SDIs) and the samples were analyzed by PIXE for about 20 elements. The mineral elements (Al, Si, Ca, Ti, Fe) exhibited a unimodal size distribution which peaked at about 6 μm, but the contribution of particles larger than 10 μm was clearly more pronounced during the day than during night. Sulphur and Br had a tendency to exhibit two modes in the submicrometer size range, with diameters at about 0.3 and 0.6 μm, respectively. The elements V and Ni, which are indicators of residual fuel burning, showed essentially one fine mode (at 0.3 μm) in addition to a coarse mode which represented the mineral dust contribution. Overall, good agreement was observed between the mass size distributions from the PCI and SDI devices. The PCI was superior to the SDI for studying the size distribution in the coarse size range, but the SDI was clearly superior for unravelling the various modes in the submicrometer size range.

Evaluation of Quantitative Exposure Assessment Method for Nanomaterials in Mixed Dust Environments: Application in Tire Manufacturing Facilities.

PubMed

Kreider, Marisa L; Cyrs, William D; Tosiano, Melissa A; Panko, Julie M

2015-11-01

Current recommendations for nanomaterial-specific exposure assessment require adaptation in order to be applied to complicated manufacturing settings, where a variety of particle types may contribute to the potential exposure. The purpose of this work was to evaluate a method that would allow for exposure assessment of nanostructured materials by chemical composition and size in a mixed dust setting, using carbon black (CB) and amorphous silica (AS) from tire manufacturing as an example. This method combined air sampling with a low pressure cascade impactor with analysis of elemental composition by size to quantitatively assess potential exposures in the workplace. This method was first pilot-tested in one tire manufacturing facility; air samples were collected with a Dekati Low Pressure Impactor (DLPI) during mixing where either CB or AS were used as the primary filler. Air samples were analyzed via scanning transmission electron microscopy (STEM) coupled with energy dispersive spectroscopy (EDS) to identify what fraction of particles were CB, AS, or 'other'. From this pilot study, it was determined that ~95% of all nanoscale particles were identified as CB or AS. Subsequent samples were collected with the Dekati Electrical Low Pressure Impactor (ELPI) at two tire manufacturing facilities and analyzed using the same methodology to quantify exposure to these materials. This analysis confirmed that CB and AS were the predominant nanoscale particle types in the mixing area at both facilities. Air concentrations of CB and AS ranged from ~8900 to 77600 and 400 to 22200 particles cm(-3), respectively. This method offers the potential to provide quantitative estimates of worker exposure to nanoparticles of specific materials in a mixed dust environment. With pending development of occupational exposure limits for nanomaterials, this methodology will allow occupational health and safety practitioners to estimate worker exposures to specific materials, even in scenarios where many particle types are present. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Small Business Innovations (Mass Microbalance)

NASA Technical Reports Server (NTRS)

1991-01-01

Femtometrics of Costa Mesa, CA, developed the Model 200-1 SAW Mass Microbalance under a NASA Small Business Innovation Research (SBIR) contract with Langley Research Center. The product is described as "the next generation of aerosol mass microbalance technology," because a new type of sensor, the Surface Acoustic Wave (SAW) piezoelectric crystal, offers mass resolution two orders of magnitude greater than the Quartz Crystal Microbalance cascade impactor (QCM) (used at Langley since 1979 for collection and measurement of aerosol particles in the upper atmosphere). The Model 200-1 SAW Mass Microbalance, which provides a 400-fold increase in mass sensitivity per unit area over the QCM, can be used for real-time particle monitoring in clean rooms, measuring chemical vapors in very low concentrations, measuring target chemicals in the stratosphere and in industry as a toxic vapor monitor.

Development of Room Temperature Stable Formulation of Formoterol Fumarate/Beclomethasone HFA pMDI

PubMed Central

Purohit, D.; Trehan, A.; Arora, V.

2009-01-01

The primary aim of present investigation was to develop and formulate room temperature stable formulation of formoterol fumarate and beclomethasone dipropionate with extra fine part size of hydrofluoroalkane pressurized metered dose inhalers. Particle size distribution of hydrofluoroalkane pressurized metered dose inhalers was evaluated using Twin Stage Glass Impinger and Anderson Cascade Impactor. A tetrafluoroethane and/or heptafluoropropane were evaluated for preparation of hydrofluoroalkane pressurized metered dose inhalers. The fine particle fractions delivered from hydrofluoroalkane propellant suspension pressurized metered dose inhalers can be predicted on the basis of formulation parameters and is dependent of metering chamber of valve and orifice size of actuators. The results presented in investigation showed the importance of formulation excipients with formulation of pressurized metered dose inhalers viz, canister, valve and actuators used in formulations.

Impact assisted segmented cutterhead

DOEpatents

Morrell, Roger J.; Larson, David A.; Ruzzi, Peter L.

1992-01-01

An impact assisted segmented cutterhead device is provided for cutting various surfaces from coal to granite. The device comprises a plurality of cutting bit segments deployed in side by side relationship to form a continuous cutting face and a plurality of impactors individually associated with respective cutting bit segments. An impactor rod of each impactor connects that impactor to the corresponding cutting bit segment. A plurality of shock mounts dampening the vibration from the associated impactor. Mounting brackets are used in mounting the cutterhead to a base machine.

Ancient impactor components preserved and reworked in martian regolith breccia Northwest Africa 7034

NASA Astrophysics Data System (ADS)

Goderis, Steven; Brandon, Alan D.; Mayer, Bernhard; Humayun, Munir

2016-10-01

Northwest Africa (NWA) 7034 and paired stones represent unique samples of martian polymict regolith breccia. Multiple breccia subsamples characterized in this work confirm highly siderophile element (HSE: Re, Os, Ir, Ru, Pt, Pd) contents that are consistently elevated (e.g., Os ∼9.3-18.4 ppb) above indigenous martian igneous rocks (mostly <5 ppb Os), equivalent to ∼3 wt% of admixed CI-type carbonaceous chondritic material, and occur in broadly chondrite-relative proportions. However, a protracted history of impactor component (metal and sulfide) breakdown and redistribution of the associated HSE has masked the original nature of the admixed meteorite signatures. The present-day 187Os/188Os ratios of 0.119-0.136 record a wider variation than observed for all major chondrite types. Combined with the measured 187Re/188Os ratios of 0.154-0.994, the range in Os isotope ratios indicates redistribution of Re and Os from originally chondritic components early in the history of the regolith commencing at ∼4.4 Ga. Superimposed recent Re mobility reflects exposure and weathering at or near the martian and terrestrial surfaces. Elevated Os concentrations (38.0 and 92.6 ppb Os), superchondritic Os/HSE ratios, and 187Os/188Os of 0.1171 and 0.1197 measured for two subsamples of the breccia suggest the redistribution of impactor material at ∼1.5-1.9 Ga, possibly overlapping with a (partial) resetting event at ∼1.4 Ga recorded by U-Pb isotope systematics in the breccia. Martian alteration of the originally chondritic HSE host phases, to form Os-Ir-rich nuggets and Ni-rich pyrite, implies the influence of potentially impact-driven hydrothermal systems. Multiple generations of impactor component admixture, redistribution, and alteration mark the formation and evolution of the martian regolith clasts and matrix of NWA 7034 and paired meteorites, from the pre-Noachian until impact ejection to Earth.

Size-segregated aerosol in a hot-spot pollution urban area: Chemical composition and three-way source apportionment.

PubMed

Bernardoni, V; Elser, M; Valli, G; Valentini, S; Bigi, A; Fermo, P; Piazzalunga, A; Vecchi, R

2017-12-01

In this work, a comprehensive characterisation and source apportionment of size-segregated aerosol collected using a multistage cascade impactor was performed. The samples were collected during wintertime in Milan (Italy), which is located in the Po Valley, one of the main pollution hot-spot areas in Europe. For every sampling, size-segregated mass concentration, elemental and ionic composition, and levoglucosan concentration were determined. Size-segregated data were inverted using the program MICRON to identify and quantify modal contributions of all the measured components. The detailed chemical characterisation allowed the application of a three-way (3-D) receptor model (implemented using Multilinear Engine) for size-segregated source apportionment and chemical profiles identification. It is noteworthy that - as far as we know - this is the first time that three-way source apportionment is attempted using data of aerosol collected by traditional cascade impactors. Seven factors were identified: wood burning, industry, resuspended dust, regional aerosol, construction works, traffic 1, and traffic 2. Further insights into size-segregated factor profiles suggested that the traffic 1 factor can be associated to diesel vehicles and traffic 2 to gasoline vehicles. The regional aerosol factor resulted to be the main contributor (nearly 50%) to the droplet mode (accumulation sub-mode with modal diameter in the range 0.5-1 μm), whereas the overall contribution from the two factors related to traffic was the most important one in the other size modes (34-41%). The results showed that applying a 3-D receptor model to size-segregated samples allows identifying factors of local and regional origin while receptor modelling on integrated PM fractions usually singles out factors characterised by primary (e.g. industry, traffic, soil dust) and secondary (e.g. ammonium sulphate and nitrate) origin. Furthermore, the results suggested that the information on size-segregated chemical composition in different size classes was exploited by the model to relate primary emissions to rapidly-formed secondary compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Game of Space Telephone

NASA Technical Reports Server (NTRS)

2005-01-01

This image shows NASA's Deep Impact impactor spacecraft while it was being built at Ball Aerospace & Technologies Corporation, Boulder, Colo. On July 2, at 10:52 p.m. Pacific time (1:52 a.m. Eastern time, July 3), the impactor will be released from Deep Impact's flyby spacecraft. One day later, it will collide with Tempel 1. The impactor cannot directly talk to Earth, so it will communicate via the flyby spacecraft during its final day.

The two spacecraft communicate at 'S-band' frequency. The impactor's S-band antenna is the rectangle-shaped object seen on the top of the impactor in this image.

Experimental and theoretical research of the interaction between high-strength supercavitation impactors and monolithic barriers in water

NASA Astrophysics Data System (ADS)

Ishchenko, A. N.; Afanas'eva, S. A.; Burkin, V. V.; Diachkovskii, A. S.; Zykova, A. I.; Khabibullin, M. V.; Chupashev, A. V.; Yugov, N. T.

2017-09-01

The article describes experimental and theoretical research of the interaction between supercavitating impactors and underwater aluminum alloy and steel barriers. Strong alloys are used for making impactors. An experimental research technique based on a high-velocity hydro-ballistic complex was developed. Mathematical simulation of the collision the impactor and barrier is based on the continuum mechanics inclusive of the deformation and destruction of interacting bodies. Calculated and experimental data on the ultimate penetration thickness of barriers made of aluminum alloy D16T and steel for the developed supercavitating impactor are obtained.

Measurement of particulates

NASA Technical Reports Server (NTRS)

Woods, D.

1980-01-01

The size distributions of particles in the exhaust plumes from the Titan rockets launched in August and September 1977 were determined from in situ measurements made from a small sampling aircraft that flew through the plumes. Two different sampling instruments were employed, a quartz crystal microbalance (QCM) cascade impactor and a forward scattering spectrometer probe (FSSP). The QCM measured the nonvolatile component of the aerosols in the plume covering an aerodynamic size ranging from 0.05 to 25 micrometers diameter. The FSSP, flown outside the aircraft under the nose section, measured both the liquid droplets and the solid particles over a size range from 0.5 to 7.5 micrometers in diameter. The particles were counted and classified into 15 size intervals. The presence of a large number of liquid droplets in the exhaust clouds is discussed and data are plotted for each launch and compared.

Methods used to calculate doses resulting from inhalation of Capstone depleted uranium aerosols.

PubMed

Miller, Guthrie; Cheng, Yung Sung; Traub, Richard J; Little, Tom T; Guilmette, Raymond A

2009-03-01

The methods used to calculate radiological and toxicological doses to hypothetical persons inside either a U.S. Army Abrams tank or Bradley Fighting Vehicle that has been perforated by depleted uranium munitions are described. Data from time- and particle-size-resolved measurements of depleted uranium aerosol as well as particle-size-resolved measurements of aerosol solubility in lung fluids for aerosol produced in the breathing zones of the hypothetical occupants were used. The aerosol was approximated as a mixture of nine monodisperse (single particle size) components corresponding to particle size increments measured by the eight stages plus the backup filter of the cascade impactors used. A Markov Chain Monte Carlo Bayesian analysis technique was employed, which straightforwardly calculates the uncertainties in doses. Extensive quality control checking of the various computer codes used is described.

Hypervelocity impact survivability experiments for carbonaceous impactors

NASA Technical Reports Server (NTRS)

Bunch, T. E.; Becker, Luann; Bada, Jeffrey; Macklin, John; Radicatidibrozolo, Filippo; Fleming, R. H.; Erlichman, Jozef

1993-01-01

We performed a series of hypervelocity impact experiments using carbon-bearing impactors (diamond, graphite, fullerenes, phthalic acid crystals, and Murchison meteorite) into Al plate at velocities between 4.2 and 6.1 km/s. These tests were made to do the following: (1) determine the survivability of carbon forms and organize molecules in low hypervelocity impact; (2) characterize carbonaceous impactor residues; and (3) determine whether or not fullerenes could form from carbonaceous impactors, under our experimental conditions, or survive as impactors. An analytical protocol of field emission SEM imagery, SEM-EDX, laser Raman spectroscopy, single and 2-stage laser mass spectrometry, and laser induced fluorescence (LIF) found the following: (1) diamonds did not survive impact at 4.8 km/s, but were transformed into various forms of disordered graphite; (2) intact, well-ordered graphite impactors did survive impact at 5.9 km/sec, but were only found in the crater bottom centers; the degree of impact-induced disorder in the graphite increases outward (walls, rims, ejecta); (3) phthalic acid crystals were destroyed on impact (at 4.2 km/s, although a large proportion of phthalic acid molecules did survive impact); (4) fullerenes did not form as products of carbonaceous impactors (5.9 - 6.1 km/s, fullerene impactor molecules mostly survived impact at 5.9 km/s; and (5) two Murchison meteorite samples (launched at 4.8 and 5.9 km/s) show preservation of some higher mass polycyclic aromatic hydrocarbons (PAHs) compared with the non-impacted sample. Each impactor type shows unique impactor residue morphologies produced at a given impact velocity. An expanded methodology is presented to announce relatively new analytical techniques together with innovative modifications to other methods that can be used to characterize small impact residues in LDEF craters, in addition to other acquired extraterrestrial samples.

Crater Morphology of Engineered and Natural Impactors into Planetary Ice

NASA Astrophysics Data System (ADS)

Danner, M.; Winglee, R.; Koch, J.

2017-12-01

Crater morphology of engineered impactors, such as those proposed for the Europa Kinetic Ice Penetrator (EKIP) mission, varies drastically from that of natural impactors (i.e. Asteroids, meteoroids). Previous work of natural impact craters in ice have been conducted with the intent to bound the thickness of Europa's ice crust; this work focuses on the depth, size, and compressional effects caused by various impactor designs, and the possible effects to the Europan surface. The present work details results from nine projectiles that were dropped on the Taku Glacier, AK at an altitude of 775 meters above surface; three rocks to simulate natural impactors, and six iterations of engineered steel and aluminum penetrator projectiles. Density measurements were taken at various locations within the craters, as well as through a cross section of the crater. Due to altitude restrictions, projectiles remained below terminal velocity. The natural/rock impact craters displayed typical cratering characteristics such as shallow, half meter scale depth, and orthogonal compressional forcing. The engineered projectiles produced impact craters with depths averaging two meters, with crater widths matching the impactor diameters. Compressional waves from the engineered impactors propagated downwards, parallel to direction of impact. Engineered impactors create significantly less lateral fracturing than natural impactors. Due to the EKIP landing mechanism, sampling of pristine ice closer to the lander is possible than previously thought with classical impact theory. Future work is planned to penetrate older, multiyear ice with higher velocity impacts.

Impact of droplet evaporation rate on resulting in vitro performance parameters of pressurized metered dose inhalers.

PubMed

Sheth, Poonam; Grimes, Matthew R; Stein, Stephen W; Myrdal, Paul B

2017-08-07

Pressurized metered dose inhalers (pMDIs) are widely used for the treatment of pulmonary diseases. The overall efficiency of pMDI drug delivery may be defined by in vitro parameters such as the amount of drug that deposits on the model throat and the proportion of the emitted dose that has particles that are sufficiently small to deposit in the lung (i.e., fine particle fraction, FPF). The study presented examines product performance of ten solution pMDI formulations containing a variety of cosolvents with diverse chemical characteristics by cascade impaction with three inlets (USP induction port, Alberta Idealized Throat, and a large volume chamber). Through the data generated in support of this study, it was demonstrated that throat deposition, cascade impactor deposition, FPF, and mass median aerodynamic diameter of solution pMDIs depend on the concentration and vapor pressure of the cosolvent, and the selection of model throat. Theoretical droplet lifetimes were calculated for each formulation using a discrete two-stage evaporation process model and it was determined that the droplet lifetime is highly correlated to throat deposition and FPF indicating that evaporation kinetics significantly influences pMDI drug delivery. Copyright © 2017 Elsevier B.V. All rights reserved.

When Worlds Collide

NASA Astrophysics Data System (ADS)

Schultz, P. H.

1997-07-01

Although considerable attention has been paid to the catastrophic fragmentation of small planetary bodies following hypervelocity collisions, laboratory experiments at the NASA Ames Vertical Gun Range allow documenting the fate of the impactor. Of particular interest is the effect of oblique impacts on curved planetary surfaces, i.e., when the size of the impactor approaches 20% of the size of the target. Such experiments reveal that the shock created at first contact disrupts and decouples the impactor before it penetrates the target for 5-6 km/s impact velocities. This process has five important consequences. First, relatively large impactor fragments can survive the collision with minimal damage (5-6 largest sizes = 10% of the impactor mass). Moreover, surface curvature ensures escape of larger impactor debris exhibiting a wide range of shocked states. Second, these fragments follow different trajectories depending on their style of failure (spallation or shear) and provenance (their location in the impactor). Third, a low impedance veneer (regolith) reduces the degree of impactor fragmentation. Fourth, the process significantly decreases the energy (peak pressure) in the target and allows its survival even for collisions with large specific energies. Nevertheless, significant residual mafic melts result through frictional heating. And fifth, nominal oblique trajectories (30 deg) become equivalent to much lower angle events (< 10 deg) as the impactor:target ratio approaches 1:4. This process can be scaled (to first order) to asteroid-size events and could provide a mechanism to produce different meteor streams and asteroid families from a single event while leaving behind an intact but mafic scar on the parent body.

Performance of a scanning mobility particle sizer in measuring diverse types of airborne nanoparticles: Multi-walled carbon nanotubes, welding fumes, and titanium dioxide spray.

PubMed

Chen, Bean T; Schwegler-Berry, Diane; Cumpston, Amy; Cumpston, Jared; Friend, Sherri; Stone, Samuel; Keane, Michael

2016-07-01

Direct-reading instruments have been widely used for characterizing airborne nanoparticles in inhalation toxicology and industrial hygiene studies for exposure/risk assessments. Instruments using electrical mobility sizing followed by optical counting, e.g., scanning or sequential mobility particle spectrometers (SMPS), have been considered as the "gold standard" for characterizing nanoparticles. An SMPS has the advantage of rapid response and has been widely used, but there is little information on its performance in assessing the full spectrum of nanoparticles encountered in the workplace. In this study, an SMPS was evaluated for its effectiveness in producing "monodisperse" aerosol and its adequacy in characterizing overall particle size distribution using three test aerosols, each mimicking a unique class of real-life nanoparticles: singlets of nearly spherical titanium dioxide (TiO2), agglomerates of fiber-like multi-walled carbon nanotube (MWCNT), and aggregates that constitutes welding fume (WF). These aerosols were analyzed by SMPS, cascade impactor, and by counting and sizing of discrete particles by scanning and transmission electron microscopy. The effectiveness of the SMPS to produce classified particles (fixed voltage mode) was assessed by examination of the resulting geometric standard deviation (GSD) from the impactor measurement. Results indicated that SMPS performed reasonably well for TiO2 (GSD = 1.3), but not for MWCNT and WF as evidenced by the large GSD values of 1.8 and 1.5, respectively. For overall characterization, results from SMPS (scanning voltage mode) exhibited particle-dependent discrepancies in the size distribution and total number concentration compared to those from microscopic analysis. Further investigation showed that use of a single-stage impactor at the SMPS inlet could distort the size distribution and underestimate the concentration as shown by the SMPS, whereas the presence of vapor molecules or atom clusters in some test aerosols might cause artifacts by counting "phantom particles." Overall, the information obtained from this study will help understand the limitations of the SMPS in measuring nanoparticles so that one can adequately interpret the results for risk assessments and exposure prevention in an occupational or ambient environment.

The cascade of HIV care among refugees and nationals in Nakivale Refugee Settlement in Uganda.

PubMed

O'Laughlin, K N; Kasozi, J; Rabideau, D J; Parker, R A; Mulogo, E; Faustin, Z M; Greenwald, K E; Doraiswamy, S; Walensky, R P; Bassett, I V

2017-08-01

Refugees living in Uganda come from HIV-endemic countries, and many remain in refugee settlements for over a decade. Our objective was to evaluate the HIV care cascade in Nakivale Refugee Settlement and to assess correlates of linkage to care. We prospectively enrolled individuals accessing clinic-based HIV testing in Nakivale Refugee Settlement from March 2013 to July 2014. Newly HIV-diagnosed clients were followed for 3 months post-diagnosis. Clients underwent a baseline survey. The following outcomes were obtained from HIV clinic registers in Nakivale: clinic attendance ('linkage to HIV care'), CD4 testing, antiretroviral therapy (ART) eligibility, and ART initiation within 90 days of testing. Descriptive data were reported as frequency with 95% confidence interval (CI) or median with interquartile range (IQR). The impact of baseline variables on linkage to care was assessed with logistic regression models. Of 6850 adult clients tested for HIV, 276 (4%; CI: 3-5%) were diagnosed with HIV infection, 148 (54%; CI: 47-60%) of those were linked to HIV care, 54 (20%; CI: 15-25%) had a CD4 test, 22 (8%; CI: 5-12%) were eligible for ART, and 17 (6%; CI: 3-10%) initiated ART. The proportions of refugees and nationals at each step of the cascade were similar. We identified no significant predictors of linkage to care. Less than a quarter of newly HIV-diagnosed clients completed ART assessment, considerably lower than in other reports from sub-Saharan Africa. Understanding which factors hinder linkage to and engagement in care in the settlement will be important to inform interventions specific for this environment. © 2017 British HIV Association.

Grooved impactor and inertial trap for sampling inhalable particulate matter

DOEpatents

Loo, Billy W.

1984-01-01

An inertial trap and grooved impactor for providing a sharp cutoff for particles over 15 microns from entering an inhalable particulate sampler. The impactor head has a tapered surface and is provided with V-shaped grooves. The tapered surface functions for reducing particle blow-off or reentrainment while the grooves prevent particle bounce. Water droplets and any resuspended material over the 15 micron size are collected by the inertial trap and deposited in a reservoir associated with the impactor.

Collection of microparticles at high balloon altitudes in the stratosphere

NASA Technical Reports Server (NTRS)

Testa, John P., Jr.; Stephens, John R.; Berg, Walter W.; Cahill, Thomas A.; Onaka, Takashi

1990-01-01

Stratospheric particles were collected between 34 and 36 km, using a combination of cascade impactors and filters lofted by a large helium balloon, and the particle concentration, size distribution, and bulk elemental composition were determined using SEM and proton-induced X-ray emission (PEXE) instrument. In addition, datailed particle morphology, elemental analysis, and electron diffraction data were obtained on 23 particles using a TEM. The concentration of particles between 0.045 and 1.0 micron in radius was found to be orders of magnitude above the concentrations predicted by the model of Hunten et al. (1980), but was consistent with balloon and satellite observations. Elemental composition analysis showed the presence of Cl, S, Ti, Fe, Br, Ni, Zr, Zn, Sr, and Cu in decreasing order of concentration. The 23 particles analyzed by TEM ranged from Al-rich silicates to almost pure Fe to one containing almost exclusively Ba and S. None were definitely chondritic in composition.

Proton-Induced X-Ray Emission Analysis of Crematorium Emissions

NASA Astrophysics Data System (ADS)

Ali, Salina; Nadareski, Benjamin; Safiq, Alexandrea; Smith, Jeremy; Yoskowitz, Josh; Labrake, Scott; Vineyard, Michael

2013-10-01

There has been considerable concern in recent years about possible mercury emissions from crematoria. We have performed a particle-induced X-ray emission (PIXE) analysis of atmospheric aerosol samples collected on the roof of the crematorium at Vale Cemetery in Schenectady, NY, to address this concern. The samples were collected with a nine-stage cascade impactor that separates the particulate matter according to particle size. The aerosol samples were bombarded with 2.2-MeV protons from the Union College 1.1-MV Pelletron Accelerator. The emitted X-rays were detected with a silicon drift detector and the X-ray energy spectra were analyzed using GUPIX software to determine the elemental concentrations. We measured significant concentrations of sulfur, phosphorus, potassium, calcium, and iron, but essentially no mercury. The lower limit of detection for mercury in this experiment was approximately 0.2 ng/m3. We will describe the experimental procedure, discuss the PIXE analysis, and present preliminary results.

Size distribution of radon daughter particles in uranium mine atmospheres.

PubMed

George, A C; Hinchliffe, L; Sladowski, R

1975-06-01

The size distribution of radon daughters was measured in several uranium mines using four compact diffusion batteries and a round jet cascade impactor. Simultaneously, measurements were made of uncombined fractions of radon daughters, radon concentration, working level and particle concentration. The size distributions found for radon daughters were log normal. The activity median diameters ranged from 0.09 mum to 0.3 mum with a mean value of 0.17 mum. Geometric standard deviations were in the range from 1.3 to 4 with a mean value of 2.7. Uncombined fractions expressed in accordance with the ICRP definition ranged from 0.004 to 0.16 with a mean value of 0.04. The radon daughter sizes in these mines are greater than the sizes assumed by various authors in calculating respiratory tract dose. The disparity may reflect the widening use of diesel-powered equipment in large uranium mines.

Soluble Nutrient and Trace Metal Fluxes from Aerosol Dry Deposition to Elkhorn Slough, CA

NASA Astrophysics Data System (ADS)

Gray, E. T.; Paytan, A.; Haskins, J.

2009-12-01

Atmospheric deposition has been widely recognized as a source of pollutants and nutrients to coastal ecosystems. Specifically, deposition includes nitrogen compounds, sulfur compounds, mercury, pesticides, phosphate, trace metals and other toxic compounds that can travel great distances in aerosols. These components can come from both natural (volcanoes, mineral dust, forest fires) and anthropogenic (fossil fuels, chemical byproducts, incineration of waste) sources. These pollutants may affect ecosystem health and water quality with environmental impacts such as eutrophication, contaminated fish and harmful algal blooms. In this study we focus on dry deposition to Elkhorn Slough, California. Size fractionated aerosol samples (PM 2.5 and PM 10) collected continuously over a seven day period using a cascade impactor are used along with a deposition model to determine the soluble nutrient and trace metal fluxes on the Elkhorn Slough ecosystem. Atmospheric deposition inputs will be compared to other sources and their potential impact evaluated.

PIXE Analysis of Indoor Aerosols

NASA Astrophysics Data System (ADS)

Johnson, Christopher; Turley, Colin; Moore, Robert; Battaglia, Maria; Labrake, Scott; Vineyard, Michael

2011-10-01

We have performed a proton-induced X-ray emission (PIXE) analysis of aerosol samples collected in academic buildings at Union College to investigate the air quality in these buildings and the effectiveness of their air filtration systems. This is also the commissioning experiment for a new scattering chamber in the Union College Ion-Beam Analysis Laboratory. The aerosol samples were collected on Kapton foils using a nine-stage cascade impactor that separates particles according to their aerodynamic size. The foils were bombarded with beams of 2.2-MeV protons from the Union College 1.1-MV Pelletron Accelerator and the X-ray products were detected with an Amptek silicon drift detector. After subtracting the contribution from the Kapton foils, the X-ray energy spectra of the aerosol samples were analyzed using GUPIX software to determine the elemental concentrations of the samples. We will describe the collection of the aerosol samples, discuss the PIXE analysis, and present the results.

Determination of the solubility and size distribution of radioactive aerosols in the uranium processing plant at NRCN.

PubMed

Kravchik, T; Oved, S; Paztal-Levy, O; Pelled, O; Gonen, R; German, U; Tshuva, A

2008-01-01

Inhalation is the main route of internal exposure to radioactive aerosols in the nuclear industry. To assess the radiation dose from the intake of these aerosols, it is necessary to know their physical (aerodynamic diameter distribution) and chemical (dissolution rate in extracellular lung fluid) characteristics. Air samples were taken from the uranium processing plant at the Nuclear Research Center, Negev. Measurements of aerodynamic diameter distribution using a cascade impactor indicated an average activity median aerodynamic diameter value close to 5 microm, in accordance with the recent recommended values of International Commission on Radiological Protection (ICRP) model. Solubility profiles of these aerosols were determined by performing in vitro solubility tests over 100 d in a simultant solution of the extracellular fluid. The tests indicated that the uranium aerosols should be assigned to an absorption between Types M and S (as defined by the ICRP Publication 66 model).

Atmospheric Aerosol Sampling with Unmanned Aircraft Systems (UAS) in Alaska: Instrument Development, Payload Integration, and Measurement Campaigns

NASA Astrophysics Data System (ADS)

Barberie, S. R.; Saiet, E., II; Hatfield, M. C.; Cahill, C. F.

2014-12-01

Atmospheric aerosols remain one of biggest variables in understanding global climate. The number of feedback loops involved in aerosol processes lead to nonlinear behavior at the systems level, making confident modeling and prediction difficult. It is therefore important to ground-truth and supplement modeling efforts with rigorous empirical measurements. To this end, the Alaska Center for Unmanned Aircraft Systems Integration (ACUASI) at the University of Alaska Fairbanks has developed a new cascade DRUM-style impactor to be mounted aboard a variety of unmanned aircraft and work in tandem with an optical particle counter for the routine collection of atmospheric aerosols. These UAS-based aerosol samplers will be employed for measurement campaigns in traditionally hazardous conditions such as volcanic plumes and over forest fires. Here we report on the development and laboratory calibration of the new instrument, the integration with UAS, and the vertical profiling campaigns being undertaken.

Novel monolithic integration scheme for high-speed electroabsorption modulators and semiconductor optical amplifiers using cascaded structure.

PubMed

Lin, Fang-Zheng; Wu, Tsu-Hsiu; Chiu, Yi-Jen

2009-06-08

A new monolithic integration scheme, namely cascaded-integration (CI), for improving high-speed optical modulation is proposed and demonstrated. High-speed electroabsorption modulators (EAMs) and semiconductor optical amplifiers (SOAs) are taken as the integrated elements of CI. This structure is based on an optical waveguide defined by cascading segmented EAMs with segmented SOAs, while high-impedance transmission lines (HITLs) are used for periodically interconnecting EAMs, forming a distributive optical re-amplification and re-modulation. Therefore, not only the optical modulation can be beneficial from SOA gain, but also high electrical reflection due to EAM low characteristic impedance can be greatly reduced. Two integration schemes, CI and conventional single-section (SS), with same total EAM- and SOA- lengths are fabricated and compared to examine the concept. Same modulation-depth against with EAM bias (up to 5V) as well as SOA injection current (up to 60mA) is found in both structures. In comparison with SS, a < 1dB extra optical-propagation loss in CI is measured due to multi-sections of electrical-isolation regions between EAMs and SOAs, suggesting no significant deterioration in CI on DC optical modulation efficiency. Lower than -12dB of electrical reflection from D.C. to 30GHz is observed in CI, better than -5dB reflection in SS for frequency of above 5GHz. Superior high-speed electrical properties in CI structure can thus lead to higher speed of electrical-to-optical (EO) response, where -3dB bandwidths are >30GHz and 13GHz for CI and SS respectively. Simulation results on electrical and EO response are quite consistent with measurement, confirming that CI can lower the driving power at high-speed regime, while the optical loss is still kept the same level. Taking such distributive advantage (CI) with optical gain, not only higher-speed modulation with high output optical power can be attained, but also the trade-off issue due to impedance mismatch can be released to reduce the driving power of modulator. Such kind of monolithic integration scheme also has potential for the applications of other high-speed optoelectronics devices.

The particle size distribution, density, and specific surface area of welding fumes from SMAW and GMAW mild and stainless steel consumables.

PubMed

Hewett, P

1995-02-01

Particle size distributions were measured for fumes from mild steel (MS) and stainless steel (SS); shielded metal arc welding (SMAW) and gas metal arc welding (GMAW) consumables. Up to six samples of each type of fume were collected in a test chamber using a micro-orifice uniform deposit (cascade) impactor. Bulk samples were collected for bulk fume density and specific surface area analysis. Additional impactor samples were collected using polycarbonate substrates and analyzed for elemental content. The parameters of the underlying mass distributions were estimated using a nonlinear least squares analysis method that fits a smooth curve to the mass fraction distribution histograms of all samples for each type of fume. The mass distributions for all four consumables were unimodal and well described by a lognormal distribution; with the exception of the GMAW-MS and GMAW-SS comparison, they were statistically different. The estimated mass distribution geometric means for the SMAW-MS and SMAW-SS consumables were 0.59 and 0.46 micron aerodynamic equivalent diameter (AED), respectively, and 0.25 micron AED for both the GMAW-MS and GMAW-SS consumables. The bulk fume densities and specific surface areas were similar for the SMAW-MS and SMAW-SS consumables and for the GMAW-MS and GMAW-SS consumables, but differed between SMAW and GMAW. The distribution of metals was similar to the mass distributions. Particle size distributions and physical properties of the fumes were considerably different when categorized by welding method. Within each welding method there was little difference between MS and SS fumes.

Airborne arsenic and urinary excretion of arsenic metabolites during boiler cleaning operations in a Slovak coal-fired power plant.

PubMed Central

Yager, J W; Hicks, J B; Fabianova, E

1997-01-01

Little information is available on the relationship between occupational exposure to inorganic arsenic in coal fly ash and urinary excretion of arsenic metabolites. This study ws undertaken in a coal-fired power plant in Slovakia during a routine maintenance outage. Arsenic was measured in the breathing zone of workers during 5 consecutive workdays, and urine samples were obtained for analysis of arsenic metabolites--inorganic arsenic (Asi), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA)--prior to the start of each shift. Results from a small number of cascade impactor air samples indicated that approximately 90% of total particle mass and arsenic was present in particle size fractions >/= 3.5 micron. The 8-hr time-weighted average (TWA) mean arsenic air concentration was 48.3 microg/m3 (range 0.17-375.2) and the mean sum of urinary arsenic (SigmaAs) metabolites was 16.9 microg As/g creatinine (range 2.6-50.8). For an 8-hr TWA of 10 microg/m3 arsenic from coal fly ash, the predicted mean concentration of the SigmaAs urinary metabolites was 13.2 microg As/G creatinine [95% confidence interval (CI), 10.1-16.3). Comparisons with previously published studies of exposure to arsenic trioxide vapors and dusts in copper smelters suggest that bioavailability of arsenic from airborne coal fly ash (as indicated by urinary excretion) is about one-third that seen in smelters and similar settings. Arsenic compound characteristics, matrix composition, and particle size distribution probably play major roles in determining actual uptake of airborne arsenic. Images Figure 1. A Figure 1. B Figure 2. PMID:9347899

"Isocrater" impacts: Conditions and mantle dynamical responses for different impactor types

NASA Astrophysics Data System (ADS)

Ruedas, Thomas; Breuer, Doris

2018-05-01

Impactors of different types and sizes can produce a final crater of the same diameter on a planet under certain conditions. We derive the condition for such "isocrater impacts" from scaling laws, as well as relations that describe how the different impactors affect the interior of the target planet; these relations are also valid for impacts that are too small to affect the mantle. The analysis reveals that in a given isocrater impact, asteroidal impactors produce anomalies in the interior of smaller spatial extent than cometary or similar impactors. The differences in the interior could be useful for characterizing the projectile that formed a given crater on the basis of geophysical observations and potentially offer a possibility to help constrain the demographics of the ancient impactor population. A series of numerical models of basin-forming impacts on Mercury, Venus, the Moon, and Mars illustrates the dynamical effects of the different impactor types on different planets. It shows that the signature of large impacts may be preserved to the present in Mars, the Moon, and Mercury, where convection is less vigorous and much of the anomaly merges with the growing lid. On the other hand, their signature will long have been destroyed in Venus, whose vigorous convection and recurring lithospheric instabilities obliterate larger coherent anomalies.

Asteroid Impact Risk: Ground Hazard versus Impactor Size

NASA Technical Reports Server (NTRS)

Mathias, Donovan; Wheeler, Lorien; Dotson, Jessie; Aftosmis, Michael; Tarano, Ana

2017-01-01

We utilized a probabilistic asteroid impact risk (PAIR) model to stochastically assess the impact risk due to an ensemble population of Near-Earth Objects (NEOs). Concretely, we present the variation of risk with impactor size. Results suggest that large impactors dominate the average risk, even when only considering the subset of undiscovered NEOs.

Sampling stratospheric aerosols with impactors

NASA Technical Reports Server (NTRS)

Oberbeck, Verne R.

1989-01-01

Derivation of statistically significant size distributions from impactor samples of rarefield stratospheric aerosols imposes difficult sampling constraints on collector design. It is shown that it is necessary to design impactors of different size for each range of aerosol size collected so as to obtain acceptable levels of uncertainty with a reasonable amount of data reduction.

The terrestrial late veneer from core disruption of a lunar-sized impactor

NASA Astrophysics Data System (ADS)

Genda, H.; Brasser, R.; Mojzsis, S. J.

2017-12-01

Overabundances in highly siderophile elements (HSEs) of Earth's mantle can be explained by conveyance from a singular, immense (D ∼ 3000 km) ;Late Veneer; impactor of chondritic composition, subsequent to lunar formation and terrestrial core-closure. Such rocky objects of approximately lunar mass (∼0.01 M⊕) ought to be differentiated, such that nearly all of their HSE payload is sequestered into iron cores. Here, we analyze the mechanical and chemical fate of the core of such a Late Veneer impactor, and trace how its HSEs are suspended - and thus pollute - the mantle. For the statistically most-likely oblique collision (∼45°), the impactor's core elongates and thereafter disintegrates into a metallic hail of small particles (∼10 m). Some strike the orbiting Moon as sesquinary impactors, but most re-accrete to Earth as secondaries with further fragmentation. We show that a single oblique impactor provides an adequate amount of HSEs to the primordial terrestrial silicate reservoirs via oxidation of (

KSC-05PD-0116

NASA Technical Reports Server (NTRS)

2005-01-01

KENNEDY SPACE CENTER, FLA. At Ball Aerospace in Boulder, Colo., the impactor on the Deep Impact spacecraft is tested. Deep Impact will probe beneath the surface of Comet Tempel 1 on July 4, 2005, when the comet is 83 million miles from Earth, and reveal the secrets of its interior. After releasing a 3- by 3-foot projectile (impactor) to crash onto the surface, Deep Impacts flyby spacecraft will collect pictures and data of how the crater forms, measuring the craters depth and diameter, as well as the composition of the interior of the crater and any material thrown out, and determining the changes in natural outgassing produced by the impact. The impactor will separate from the flyby spacecraft 24 hours before it impacts the surface of Tempel 1's nucleus. The impactor delivers 19 Gigajoules (that's 4.8 tons of TNT) of kinetic energy to excavate the crater. This kinetic energy is generated by the combination of the mass of the impactor and its velocity when it impacts. To accomplish this feat, the impactor uses a high-precision star tracker, the Impactor Target Sensor (ITS), and Auto-Navigation algorithms developed by Jet Propulsion Laboratory to guide it to the target. Deep Impact is a NASA Discovery mission. Launch of Deep Impact is scheduled for Jan. 12 from Launch Pad 17-B, Cape Canaveral Air Force Station, Fla.

U.S.-MEXICO BORDER PROGRAM ARIZONA BORDER STUDY--STANDARD OPERATING PROCEDURE FOR HARVARD PM IMPACTOR CALIBRATION AND LEAK TESTING (UA-L-7.1)

EPA Science Inventory

The purpose of this SOP is to describe the procedures for the periodic calibration and leak testing of Harvard particulate matter (PM) impactor units. This procedure applies directly to the calibration and leak testing of Harvard PM impactor units used during the Arizona NHEXAS ...

49 CFR 572.185 - Thorax (upper torso) assembly.

Code of Federal Regulations, 2010 CFR

2010-10-01

... impactor at contact with the thorax. The non-struck side arm is oriented vertically, pointing downward. The...); (iv) The impactor is guided, if needed, so that at contact with the thorax its longitudinal axis is... rib not less than 37 mm and not greater than 44 mm. (ii) The impactor force shall be computed as the...

49 CFR 572.185 - Thorax (upper torso) assembly.

Code of Federal Regulations, 2014 CFR

2014-10-01

... impactor at contact with the thorax. The non-struck side arm is oriented vertically, pointing downward. The...); (iv) The impactor is guided, if needed, so that at contact with the thorax its longitudinal axis is... rib not less than 37 mm and not greater than 44 mm. (ii) The impactor force shall be computed as the...

49 CFR 572.185 - Thorax (upper torso) assembly.

Code of Federal Regulations, 2013 CFR

2013-10-01

... impactor at contact with the thorax. The non-struck side arm is oriented vertically, pointing downward. The...); (iv) The impactor is guided, if needed, so that at contact with the thorax its longitudinal axis is... rib not less than 37 mm and not greater than 44 mm. (ii) The impactor force shall be computed as the...

49 CFR 572.185 - Thorax (upper torso) assembly.

Code of Federal Regulations, 2011 CFR

2011-10-01

... impactor at contact with the thorax. The non-struck side arm is oriented vertically, pointing downward. The...); (iv) The impactor is guided, if needed, so that at contact with the thorax its longitudinal axis is... rib not less than 37 mm and not greater than 44 mm. (ii) The impactor force shall be computed as the...

49 CFR 572.185 - Thorax (upper torso) assembly.

Code of Federal Regulations, 2012 CFR

2012-10-01

... impactor at contact with the thorax. The non-struck side arm is oriented vertically, pointing downward. The...); (iv) The impactor is guided, if needed, so that at contact with the thorax its longitudinal axis is... rib not less than 37 mm and not greater than 44 mm. (ii) The impactor force shall be computed as the...

NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR HARVARD PM IMPACTOR CALIBRATION AND LEAK TESTING (UA-L-7.1)

EPA Science Inventory

The purpose of this SOP is to describe the procedures for the periodic calibration and leak testing of Harvard particulate matter (PM) impactor units. This procedure applies directly to the calibration and leak testing of Harvard PM impactor units used during the Arizona NHEXAS ...

HIV testing and the care continuum among transgender women: population estimates from Rio de Janeiro, Brazil

PubMed Central

Jalil, Emilia M.; Wilson, Erin C.; Luz, Paula M.; Velasque, Luciane; Moreira, Ronaldo I.; Castro, Cristiane V.; Monteiro, Laylla; Garcia, Ana Cristina F.; Cardoso, Sandra W.; Coelho, Lara E.; McFarland, Willi; Liu, Albert Y.; Veloso, Valdilea G.; Buchbinder, Susan; Grinsztejn, Beatriz

2017-01-01

Abstract Introduction: Evidence suggests that, of all affected populations, transgender women (transwomen) may have the heaviest HIV burden worldwide. Little is known about HIV linkage and care outcomes for transwomen. We aimed to estimate population-level indicators of the HIV cascade of care continuum, and to evaluate factors associated with viral suppression among transwomen in Rio de Janeiro, Brazil. Methods: We conducted a respondent-driven sampling (RDS) study of transwomen from August 2015 to January 2016 in Rio de Janeiro, Brazil and collected data on linkage and access to care, antiretroviral treatment and performed HIV viral load testing. We derived population-based estimates of cascade indicators using sampling weights and conducted RDS-weighted logistic regression analyses to evaluate correlates of viral suppression (viral load ≤50 copies/mL). Results: Of the 345 transwomen included in the study, 89.2% (95% CI 55–100%) had been previously tested for HIV, 77.5% (95% CI 48.7–100%) had been previously diagnosed with HIV, 67.2% (95% CI 39.2–95.2) reported linkage to care, 62.2% (95% CI 35.4–88.9) were currently on ART and 35.4% (95% CI 9.5–61.4%) had an undetectable viral load. The final adjusted RDS-weighted logistic regression model for viral suppression indicated that those who self-identified as black (adjusted odds ratio [aOR] 0.06, 95% CI 0.01–0.53, p < 0.01), reported earning ≤U$160/month (aOR 0.11, 95% CI 0.16–0.87, p = 0.04) or reported unstable housing (aOR 0.08, 95% CI 0.01–0.43, p < 0.01) had significantly lower odds of viral suppression. Conclusions: Our cascade indicators for transwomen showed modest ART use and low viral suppression rates. Multi-level efforts including gender affirming care provision are urgently needed to decrease disparities in HIV clinical outcomes among transwomen and reduce secondary HIV transmission to their partners. PMID:28953323

16 CFR Figure 5 to Subpart A of... - Impactor

Code of Federal Regulations, 2011 CFR

2011-01-01

... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Impactor 5 Figure 5 to Subpart A of Part 1201 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR ARCHITECTURAL GLAZING MATERIALS The Standard Pt. 1201, Subpt. A, Fig. 5 Figure 5 to Subpart A of Part 1201—Impactor EC03OC91.00...

16 CFR Figure 5 to Subpart A of... - Impactor

Code of Federal Regulations, 2010 CFR

2010-01-01

... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Impactor 5 Figure 5 to Subpart A of Part 1201 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR ARCHITECTURAL GLAZING MATERIALS The Standard Pt. 1201, Subpt. A, Fig. 5 Figure 5 to Subpart A of Part 1201—Impactor EC03OC91.00...

16 CFR Figure 5 to Subpart A of... - Impactor

Code of Federal Regulations, 2013 CFR

2013-01-01

... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Impactor 5 Figure 5 to Subpart A of Part 1201 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR ARCHITECTURAL GLAZING MATERIALS The Standard Pt. 1201, Subpt. A, Fig. 5 Figure 5 to Subpart A of Part 1201—Impactor EC03OC91.00...

16 CFR Figure 5 to Subpart A of... - Impactor

Code of Federal Regulations, 2014 CFR

2014-01-01

... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Impactor 5 Figure 5 to Subpart A of Part 1201 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR ARCHITECTURAL GLAZING MATERIALS The Standard Pt. 1201, Subpt. A, Fig. 5 Figure 5 to Subpart A of Part 1201—Impactor EC03OC91.00...

16 CFR Figure 5 to Subpart A of... - Impactor

Code of Federal Regulations, 2012 CFR

2012-01-01

... 16 Commercial Practices 2 2012-01-01 2012-01-01 false Impactor 5 Figure 5 to Subpart A of Part 1201 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR ARCHITECTURAL GLAZING MATERIALS The Standard Pt. 1201, Subpt. A, Fig. 5 Figure 5 to Subpart A of Part 1201—Impactor EC03OC91.00...

One-Way Trip to Tempel

NASA Technical Reports Server (NTRS)

2005-01-01

[figure removed for brevity, see original site] Quick Time Movie for PIA02135 Impactor Targeting Sensor Approach

This movie shows Deep Impact's impactor probe approaching comet Tempel 1. It is made up of images taken by the probe's impactor targeting sensor. The probe collided with the comet at 10:52 p.m. Pacific time, July 3 (1:52 a.m. Eastern time, July 4).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Randolph, B.

Composite liners have been fabricated for the Los Alamos liner driven HEDP experiments using impactors formed by physical vapor deposition (PVD), electroplating, machining and shrink fitting. Chemical vapor deposition (CVD) has been proposed for some ATLAS liner applications. This paper describes the processes used to fabricate machined and shrink fitted impactors which have been used for copper impactors in 1100 aluminum liners and 6061 T-6 aluminum impactors in 1100 aluminum liners. The most successful processes have been largely empirically developed and rely upon a combination of shrink fitted and light press fitting. The processes used to date will be describedmore » along with some considerations for future composite liners requirements in the HEDP Program.« less

A primordial origin for the compositional similarity between the Earth and the Moon.

PubMed

Mastrobuono-Battisti, Alessandra; Perets, Hagai B; Raymond, Sean N

2015-04-09

Most of the properties of the Earth-Moon system can be explained by a collision between a planetary embryo (giant impactor) and the growing Earth late in the accretion process. Simulations show that most of the material that eventually aggregates to form the Moon originates from the impactor. However, analysis of the terrestrial and lunar isotopic compositions show them to be highly similar. In contrast, the compositions of other Solar System bodies are significantly different from those of the Earth and Moon, suggesting that different Solar System bodies have distinct compositions. This challenges the giant impact scenario, because the Moon-forming impactor must then also be thought to have a composition different from that of the proto-Earth. Here we track the feeding zones of growing planets in a suite of simulations of planetary accretion, to measure the composition of Moon-forming impactors. We find that different planets formed in the same simulation have distinct compositions, but the compositions of giant impactors are statistically more similar to the planets they impact. A large fraction of planet-impactor pairs have almost identical compositions. Thus, the similarity in composition between the Earth and Moon could be a natural consequence of a late giant impact.

Miniaturized inertial impactor for personal airborne particulate monitoring: Prototyping

NASA Astrophysics Data System (ADS)

Pasini, Silvia; Bianchi, Elena; Dubini, Gabriele; Cortelezzi, Luca

2017-11-01

Computational fluid dynamic (CFD) simulations allowed us to conceive and design a miniaturized inertial impactor able to collect fine airborne particulate matter (PM10, PM2.5 and PM1). We created, by 3D printing, a prototype of the impactor. We first performed a set of experiments by applying a suction pump to the outlets and sampling the airborne particulate of our laboratory. The analysis of the slide showed a collection of a large number of particles, spanning a wide range of sizes, organized in a narrow band located below the exit of the nozzle. In order to show that our miniaturized inertial impactor can be truly used as a personal air-quality monitor, we performed a second set of experiments where the suction needed to produce the airflow through the impactor is generated by a human being inhaling through the outlets of the prototype. To guarantee a number of particles sufficient to perform a quantitative characterization, we collected particles performing ten consecutive deep inhalations. Finally, the potentiality for realistic applications of our miniaturized inertial impactor used in combination with a miniaturized single-particle detector will be discussed. CARIPLO Fundation - project MINUTE (Grant No. 2011-2118).

Dynamics of yield-stress droplets: Morphology of impact craters

NASA Astrophysics Data System (ADS)

Neufeld, Jerome; Sohr, David; Ferrari, Leo; Dalziel, Stuart

2017-11-01

Yield strength can play an important role for the dynamics of droplets impacting on surfaces, whether at the industrial or planetary scale, and can capture a zoo of impact crater morphologies, from simple parabolic craters, to more complex forms with forms with, for example, multiple rings, central peaks. Here we show that the morphology of planetary impact craters can be reproduced in the laboratory using carbopol, a transparent yield-stress fluid, as both impactor and bulk fluid. Using high-speed video photography, we characterise the universal, transient initial excavation stage of impact and show the dependence of the subsequent relaxation to final crater morphology on impactor size, impact speed and yield stress. To further interrogate our laboratory impacts, we dye our impactor to map its final distribution and use particle tracking to determine the flow fields during impact and the maximal extent of the yield surface. We characterise the flow-fields induced during impact, and the maximal extent of the yield surface, by tracking particles within the bulk fluid and map the distribution of impactor and bulk by tracing the final distribution of dyed impactor. The results of laboratory impact droplets are used to infer the properties of planetary impactors, and aid in inter.

Limitations of high dose carrier based formulations.

PubMed

Yeung, Stewart; Traini, Daniela; Tweedie, Alan; Lewis, David; Church, Tanya; Young, Paul M

2018-06-10

This study was performed to investigate how increasing the active pharmaceutical ingredient (API) content within a formulation affects the dispersion of particles and the aerosol performance efficiency of a carrier based dry powder inhalable (DPI) formulation, using a custom dry powder inhaler (DPI) development rig. Five formulations with varying concentrations of API beclomethasone dipropionate (BDP) between 1% and 30% (w/w) were formulated as a multi-component carrier system containing coarse lactose and fine lactose with magnesium stearate. The morphology of the formulation and each component were investigated using scanning electron micrographs while the particle size was measured by laser diffraction. The aerosol performance, in terms of aerodynamic diameter, was assessed using the British pharmacopeia Apparatus E cascade impactor (Next generation impactor). Chemical analysis of the API was observed by high performance liquid chromatography (HPLC). Increasing the concentration of BDP in the blend resulted in increasing numbers and size of individual agglomerates and densely packed BDP multi-layers on the surface of the lactose carrier. BDP present within the multi-layer did not disperse as individual primary particles but as dense agglomerates, which led to a decrease in aerosol performance and increased percentage of BDP deposition within the Apparatus E induction port and pre-separator. As the BDP concentration in the blends increases, aerosol performance of the formulation decreases, in an inversely proportional manner. Concurrently, the percentage of API deposition in the induction port and pre-separator could also be linked to the amount of micronized particles (BDP and Micronized composite carrier) present in the formulation. The effect of such dose increase on the behaviour of aerosol dispersion was investigated to gain greater insight in the development and optimisation of higher dosed carrier-based formulations. Copyright © 2018 Elsevier B.V. All rights reserved.

Multi-walled carbon nanotubes: sampling criteria and aerosol characterization

PubMed Central

Chen, Bean T.; Schwegler-Berry, Diane; McKinney, Walter; Stone, Samuel; Cumpston, Jared L.; Friend, Sherri; Porter, Dale W.; Castranova, Vincent; Frazer, David G.

2015-01-01

This study intends to develop protocols for sampling and characterizing multi-walled carbon nanotube (MWCNT) aerosols in workplaces or during inhalation studies. Manufactured dry powder containing MWCNT’s, combined with soot and metal catalysts, form complex morphologies and diverse shapes. The aerosols, examined in this study, were produced using an acoustical generator. Representative samples were collected from an exposure chamber using filters and a cascade impactor for microscopic and gravimetric analyses. Results from filters showed that a density of 0.008–0.10 particles per µm2 filter surface provided adequate samples for particle counting and sizing. Microscopic counting indicated that MWCNT’s, resuspended at a concentration of 10 mg/m3, contained 2.7 × 104 particles/cm3. Each particle structure contained an average of 18 nanotubes, resulting in a total of 4.9 × 105 nanotubes/cm3. In addition, fibrous particles within the aerosol had a count median length of 3.04 µm and a width of 100.3 nm, while the isometric particles had a count median diameter of 0.90 µm. A combination of impactor and microscopic measurements established that the mass median aerodynamic diameter of the mixture was 1.5 µm. It was also determined that the mean effective density of well-defined isometric particles was between 0.71 and 0.88 g/cm3, and the mean shape factor of individual nanotubes was between 1.94 and 2.71. The information obtained from this study can be used for designing animal inhalation exposure studies and adopted as guidance for sampling and characterizing MWCNT aerosols in workplaces. The measurement scheme should be relevant for any carbon nanotube aerosol. PMID:23033994

Detectability of Chelyabinsk-like impactors with Pan-STARRS

NASA Astrophysics Data System (ADS)

Micheli, Marco; Wainscoat, Richard J.; Denneau, Larry

2018-03-01

In this work we present the results of our analysis of the detectability of an object in the size range of the recent Chelyabinsk impactor under the current discovery and follow-up capabilities, using the specific observational strategy of the Pan-STARRS survey as a reference point. We first discuss the observability of real-life cases inspired by the impact trajectories of 2008 TC3, 2014 AA, the past Earth encounters with 2014 RC and 2015 TB145, the upcoming fly-by of 2012 TC4 and the Chelyabinsk event. We then expand our analysis with the investigation of synthetic impactors with realistic orbital distributions. Among the various conclusions of our analysis, we discuss how the time of first detectability of an object does not necessarily correspond to the moment when that same object can be recognized as an impactor. We also point out how objects discovered only a few days before impact can be immediately identified as impactors, partly thanks to the good astrometric quality that telescopes like Pan-STARRS currently achieve.

KSC-05PD-0114

NASA Technical Reports Server (NTRS)

2005-01-01

the Fischer Assembly building at Ball Aerospace in Boulder, Colo. Deep Impact will probe beneath the surface of Comet Tempel 1 on July 4, 2005, when the comet is 83 million miles from Earth, and reveal the secrets of its interior. After releasing a 3- by 3- foot projectile (impactor) to crash onto the surface, Deep Impacts flyby spacecraft will collect pictures and data of how the crater forms, measuring the craters depth and diameter, as well as the composition of the interior of the crater and any material thrown out, and determining the changes in natural outgassing produced by the impact. The impactor will separate from the flyby spacecraft 24 hours before it impacts the surface of Tempel 1's nucleus. The impactor delivers 19 Gigajoules (that's 4.8 tons of TNT) of kinetic energy to excavate the crater. This kinetic energy is generated by the combination of the mass of the impactor and its velocity when it impacts. To accomplish this feat, the impactor uses a high-precision star tracker, the Impactor Target Sensor (ITS), and Auto-Navigation algorithms developed by Jet Propulsion Laboratory to guide it to the target. Deep Impact is a NASA Discovery mission. Launch of Deep Impact is scheduled for Jan. 12 from Launch Pad 17-B, Cape Canaveral Air Force Station, Fla.

Design and Use of a Guided Weight Impactor to Impart Barely Visible Impact Damage

NASA Technical Reports Server (NTRS)

Lovejoy, Andrew E.; Przekop, Adam

2016-01-01

Aircraft structure is required to demonstrate satisfaction of the FAR requirements for Category 1, such as barely visible impact damage (BVID). Typical aircraft structure is impacted using a dropped weight impactor, which can impart BVID to the top surface of the structure. A recent test of a multi-bay box (MBB) composite test article, that represents an 80% scale center section of a hybrid wing body aircraft, required impact to be in a direction other than vertical from above, but still in an direction that is normal to the surface. This requirement eliminated the use of the conventional dropped weight impactor. Therefore, a design study was undertaken to determine the most effective way to efficiently and reliably impact the MBB. The chosen design was a guided weight impactor that is gravity driven. This paper describes the design of the guided weight impactor, and presents the results of its use for imparting BVID to the MBB. The guided weight impactor was seen to be a very reliable method to impart BVID, while at the same time having the capability to be highly configurable for use on other aircraft structure that is impacted at a variety of impact energies and from a variety of directions.

Comparative study for hardwood and softwood forest biomass: chemical characterization, combustion phases and gas and particulate matter emissions.

PubMed

Amaral, Simone Simões; de Carvalho, João Andrade; Costa, Maria Angélica Martins; Soares Neto, Turíbio Gomes; Dellani, Rafael; Leite, Luiz Henrique Scavacini

2014-07-01

Two different types of typical Brazilian forest biomass were burned in the laboratory in order to compare their combustion characteristics and pollutant emissions. Approximately 2 kg of Amazon biomass (hardwood) and 2 kg of Araucaria biomass (softwood) were burned. Gaseous emissions of CO2, CO, and NOx and particulate matter smaller than 2.5 μm (PM2.5) were evaluated in the flaming and smoldering combustion phases. Temperature, burn rate, modified combustion efficiency, emissions factor, and particle diameter and concentration were studied. A continuous analyzer was used to quantify gas concentrations. A DataRam4 and a Cascade Impactor were used to sample PM2.5. Araucaria biomass (softwood) had a lignin content of 34.9%, higher than the 23.3% of the Amazon biomass (hardwood). CO2 and CO emissions factors seem to be influenced by lignin content. Maximum concentrations of CO2, NOx and PM2.5 were observed in the flaming phase. Copyright © 2014 Elsevier Ltd. All rights reserved.

Aerosol deposition in the human respiratory tract

NASA Astrophysics Data System (ADS)

Winchester, John W.; Jones, Donald L.; Mu-tian, Bi

1984-04-01

Rising sulfur dioxide emissions from increased coal combustion present risks, not only of acid rain, but also to health by inhalation of the SO 2 and acid to the lung. We are investigating human inhalation of ppm SO 2 concentrations mixed with aerosol of submicrometer aqueous salt droplets to determine the effects on lung function and body chemistry. Unlike some investigators, we emphasize ammonium sulfate and trace element aerosol composition which simulates ambient air; aerosol pH, relative humidity, and temperature control to reveal gas-particle reaction mechanisms; and dose estimates from length of exposure, SO 2 concentration, and a direct measurement of respiratory deposition of aerosol as a function of particle size by cascade impactor sampling and elemental analysis by PIXE. Exposures, at rest or during exercise, are in a walk-in chamber at body temperature and high humidity to simulate Florida's summer climate. Lung function measurement by spirometry is carried out immediately after exposure. The results are significant in relating air quality to athletic performance and to public health in the southeastern United States.

Environmental Health Hazards of e-Cigarettes and their Components: Oxidants and Copper in e-cigarette aerosols

PubMed Central

Lerner, Chad A.; Sundar, Isaac K.; Watson, Richard M.; Elder, Alison; Jones, Ryan; Done, Douglas; Kurtzman, Rachel; Ossip, Deborah J.; Robinson, Risa; McIntosh, Scott; Rahman, Irfan

2014-01-01

To narrow the gap in our understanding of potential oxidative properties associated with Electronic Nicotine Delivery systems (ENDS) i.e. e-cigarettes, we employed semi-quantitative methods to detect oxidant reactivity in disposable components of ENDS/e-cigarettes (batteries and cartomizers) using a fluorescein indicator. These components exhibit oxidants/reactive oxygen species reactivity similar to used conventional cigarette filters. Oxidants/reactive oxygen species reactivity in e-cigarette aerosols was also similar to oxidant reactivity in cigarette smoke. A cascade particle impactor allowed sieving of a range of particle size distributions between 0.450 and 2.02 μm in aerosols from an e-cigarette. Copper, being among these particles, is 6.1 times higher per puff than reported previously for conventional cigarette smoke. The detection of a potentially cytotoxic metal as well as oxidants from e-cigarette and its components raises concern regarding the safety of e-cigarettes use and the disposal of e-cigarette waste products into the environment. PMID:25577651

Development of Biodegradable Polycation-Based Inhalable Dry Gene Powders by Spray Freeze Drying

PubMed Central

Okuda, Tomoyuki; Suzuki, Yumiko; Kobayashi, Yuko; Ishii, Takehiko; Uchida, Satoshi; Itaka, Keiji; Kataoka, Kazunori; Okamoto, Hirokazu

2015-01-01

In this study, two types of biodegradable polycation (PAsp(DET) homopolymer and PEG-PAsp(DET) copolymer) were applied as vectors for inhalable dry gene powders prepared by spray freeze drying (SFD). The prepared dry gene powders had spherical and porous structures with a 5~10-μm diameter, and the integrity of plasmid DNA could be maintained during powder production. Furthermore, it was clarified that PEG-PAsp(DET)-based dry gene powder could more sufficiently maintain both the physicochemical properties and in vitro gene transfection efficiencies of polyplexes reconstituted after powder production than PAsp(DET)-based dry gene powder. From an in vitro inhalation study using an Andersen cascade impactor, it was demonstrated that the addition of l-leucine could markedly improve the inhalation performance of dry powders prepared by SFD. Following pulmonary delivery to mice, both PAsp(DET)- and PEG-PAsp(DET)-based dry gene powders could achieve higher gene transfection efficiencies in the lungs compared with a chitosan-based dry gene powder previously reported by us. PMID:26343708

Physico-chemical characterization of grain dust in storage air of Bangalore.

PubMed

Mukherjee, A K; Nag, D P; Kakde, Y; Babu, K R; Prdkash, M N; Rao, S R

1998-06-01

An Anderson personal cascade impactor was used to study the particle mass size distribution in the storage air of two major grain storage centers in Bangalore. Dust levels in storage air as well as the personal exposures of workers were determined along with a detailed study on the particle size distribution. Protein and carbohydrate content of the dust were also determined respectively in the phosphate buffer saline (PBS) and water extracts by using the standard analytical techniques. Personal exposures in both of the grain storage centers have been found to be much above the limit prescribed by ACGIH (1995-96). But the results of particle size analysis showed a higher particle mass distribution in the non-respirable size range. The mass median diameters (MMD) of the storage air particulate of both the centers were found to be beyond the respirable range. Presence of protein and carbohydrate in the storage air dust is indicative of the existence of glyco-proteins, mostly of membrane origin.

Particle size distributions of currently used pesticides in ambient air of an agricultural Mediterranean area

NASA Astrophysics Data System (ADS)

Coscollà, Clara; Muñoz, Amalia; Borrás, Esther; Vera, Teresa; Ródenas, Milagros; Yusà, Vicent

2014-10-01

This work presents first data on the particle size distribution of 16 pesticides currently used in Mediterranean agriculture in the atmosphere. Particulate matter air samples were collected using a cascade impactor distributed into four size fractions in a rural site of Valencia Region, during July to September in 2012 and from May to July in 2013. A total of 16 pesticides were detected, including six fungicides, seven insecticides and three herbicides. The total concentrations in the particulate phase (TSP: Total Suspended Particulate) ranged from 3.5 to 383.1 pg m-3. Most of the pesticides (such as carbendazim, tebuconazole, chlorpyrifos-ethyl and chlorpyrifos-methyl) were accumulated in the ultrafine-fine (<1 μm) and coarse (2.5-10 μm) particle size fractions. Others like omethoate, dimethoate and malathion were presented only in the ultrafine-fine size fraction (<1 μm). Finally, diuron, diphenylamine and terbuthylazine-desethyl-2-OH also show a bimodal distribution but mainly in the coarse size fractions.

Particle size dependence of alkali and alkaline earth metal enrichment in marine aerosols from Bermuda

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoffman, E.J.; Hoffman, G.L.; Duce, R.A.

1980-10-20

Three cascade impactor samples were collected from a 20-m-high tower on the southeastern coast of Bermuda. These samples were analyzed for Na, K, Ca, Mg, and Fe by atomic absorption spectrophotometry. When the alkali-alkakine earth metal concentrations are corrected for a soil-derived component, utilizing the atmospheric Fe concentrations, Mg, Ca, and Na are found to be present in the same relative abundances as in seawater for all particle sizes sampled. Potassium also shows no deviation from a bulk seawater composition for particles with radii greater than approx.0.5 ..mu..m. However, excess K above that expected from either a bulk seawater ormore » soil source is observed on particles with radii less than approx.0.5 ..mu..m. While oceanic chemical fractionation processes during bubble bursting may be responsible for this excess small particle K, it is most likely due to long-range transport of K-rich particles of terrestrial vegetative origin.« less

Optimisation of powders for pulmonary delivery using supercritical fluid technology.

PubMed

Rehman, Mahboob; Shekunov, Boris Y; York, Peter; Lechuga-Ballesteros, David; Miller, Danforth P; Tan, Trixie; Colthorpe, Paul

2004-05-01

Supercritical fluid technology exploited in this work afforded single-step production of respirable particles of terbutaline sulphate (TBS). Different crystal forms of TBS were produced consistently, including two polymorphs, a stoichiometric monohydrate and amorphous material as well as particles with different degrees of crystallinity, size, and morphology. Different solid-state and surface characterisation techniques were applied in conjunction with measurements of powder flow properties using AeroFlow device and aerosol performance by Andersen Cascade Impactor tests. Improved fine particle fraction (FPF) was demonstrated for some powders produced by the SCF process when compared to the micronised material. Such enhanced flow properties and dispersion correlated well with the reduced surface energy parameters demonstrated by these powders. It is shown that semi-crystalline particles exhibited lower specific surface energy leading to a better performance in the powder flow and aerosol tests than crystalline materials. This difference of the surface and bulk crystal structure for selected powder batches is explained by the mechanism of precipitation in SCF which can lead to surface conditioning of particles produced.

Separation Anxiety Over for Deep Impact

NASA Technical Reports Server (NTRS)

2005-01-01

This image of Deep Impact's impactor probe was taken by the mission's mother ship, or flyby spacecraft, after the two separated at 11:07 p.m. Pacific time, July 2 (2:07 a.m. Eastern time, July 3). The impactor is scheduled to collide with comet Tempel 1 at 10:52 p.m. Pacific time, July 3 (1:52 a.m. Eastern time, July 4). The impactor can be seen at the center of the image.

GPU-accelerated computational tool for studying the effectiveness of asteroid disruption techniques

NASA Astrophysics Data System (ADS)

Zimmerman, Ben J.; Wie, Bong

2016-10-01

This paper presents the development of a new Graphics Processing Unit (GPU) accelerated computational tool for asteroid disruption techniques. Numerical simulations are completed using the high-order spectral difference (SD) method. Due to the compact nature of the SD method, it is well suited for implementation with the GPU architecture, hence solutions are generated at orders of magnitude faster than the Central Processing Unit (CPU) counterpart. A multiphase model integrated with the SD method is introduced, and several asteroid disruption simulations are conducted, including kinetic-energy impactors, multi-kinetic energy impactor systems, and nuclear options. Results illustrate the benefits of using multi-kinetic energy impactor systems when compared to a single impactor system. In addition, the effectiveness of nuclear options is observed.

Structure Damage Simulations Accounting for Inertial Effects and Impact and Optimization of Grid-Stiffened Non-Circular Shells

NASA Technical Reports Server (NTRS)

Mei, Chuh; Jaunky, Navin

1999-01-01

The goal of this research project is to develop modelling and analysis strategy for the penetration of aluminium plates impacted by titanium impactors. Finite element analysis is used to study the penetration of aluminium plates impacted by titanium impactors in order to study the effect of such uncontained engine debris impacts on aircraft-like skin panels. LS-DYNA3D) is used in the simulations to model the impactor, test fixture frame and target barrier plate. The effects of mesh refinement, contact modeling, and impactor initial velocity and orientation were studied. The research project also includes development of a design tool for optimum design of grid-stiffened non-circular shells or panels subjected to buckling.

A Virtual Environment for Resilient Infrastructure Modeling and Design

DTIC Science & Technology

2015-09-01

Security CI Critical Infrastructure CID Center for Infrastructure Defense CSV Comma Separated Value DAD Defender-Attacker-Defender DHS Department...responses to disruptive events (e.g., cascading failure behavior) in a context- rich , controlled environment for exercises, education, and training...The general attacker-defender (AD) and defender-attacker-defender ( DAD ) models for CI are defined in Brown et al. (2006). These models help

Australasian microtektites: Impactor identification using Cr, Co and Ni ratios

NASA Astrophysics Data System (ADS)

Folco, L.; Glass, B. P.; D'Orazio, M.; Rochette, P.

2018-02-01

Impactor identification is one of the challenges of large-scale impact cratering studies due to the dilution of meteoritic material in impactites (typically < 1 wt%). The nature of the impactor that generated the Australasian tektite/microtektite strewn field, i.e., the largest Cenozoic strewn field (∼15% of the Earth's surface), the youngest (∼0.78 Myr old) on Earth, and the only one without an associated impact crater so far, is an outstanding issue. We identify a chondritic impactor signature in 77 Australasian microtektites (size range: ∼200-700 μm) from within 3000 km from the hypothetical impact location in Indochina (∼17°N, 107°E) based on variations of Cr, Co and Ni interelement ratios in a Co/Ni vs Cr/Ni space (46 microtektites analyzed in this work by Laser Ablation-Inductively Coupled Plasma -Mass Spectrometry and 31 from literature by means of Neutron Activation Analyses with Cr, Co and Ni concentrations up to ∼370, 50 and 680 μg/g, respectively). Despite substantial overlap in Cr/Ni versus Co/Ni composition for several meteorite types with chondritic composition (chondrites and primitive achondrites), regression calculation based on ∼85% of the studied microtektites best fit a mixing line between crustal compositions and an LL chondrite. However, due to some scatter mainly in the Cr versus Ni ratios in the considered dataset, an LL chondrite may not be the best fit to the data amongst impactors of primitive compositions. Eight high Ni/Cr and five low Ni/Cr outlier microtektites (∼15% in total) deviate from the above mixing trend, perhaps resulting from incomplete homogenization of heterogeneous impactor and target precursor materials at the microtektite scale, respectively. Together with previous evidence from the ∼35 Myr old Popigai impact spherules and the ∼1 Myr old Ivory Coast microtektites, our finding suggests that at least three of the five known Cenozoic distal impact ejecta were generated by the impacts of large stony asteroids of chondritic composition, and possibly of ordinary chondritic composition. The impactor signature found in Australasian microtektites documents mixing of target and impactor melts upon impact cratering. This requires target-impactor mixing in both the two competing models in literature for the formation of the Australasian tektites/microtektites: the impact cratering and low-altitude airburst plume models.

New Analysis Of The Baptistina Asteroid Family: Implications For Its Link With The K/t Impactor

NASA Astrophysics Data System (ADS)

Delbo, Marco; Nesvorny, D.; Licandro, J.; Ali-Lagoa, V.

2012-10-01

The Baptistina Asteroid Family (BAF) is the result of the breakup of an asteroid roughly 100 million years ago. This family is the source of meteoroids and near-Earth asteroids and likely caused an asteroid shower of impactors on our Earth. Bottke et al. (2007) proposed a link between the BAF and the K/T impactor, based on the favorable timing, large probability of a terrestrial impact of one 10-km BAF asteroid, and the Sloan colors of the BAF members, indicating that the BAF may have composition consistent with the K/T impactor (CM2-type carbonaceous meteorite, as inferred from chromium studies at different K/T boundary sites; Alvarez et al. 1980, Kring et al. 2007). The relationship between the BAF and K/T impactor is now controversial. Masiero et al. (2011) found that the albedo of BAF family members is 0.15, significantly higher than expected for a dark carbonaceous parent body. Also, Reddy et al. (2011) reported the spectroscopic observations of (298) Baptistina and objects in the general neighborhood of the BAF, and suggested the BAF includes a mixture of spectroscopic types that is not very different from the background (mostly S-type asteroids in the background Flora family). Unfortunately, Reddy et al. observed only the large asteroids near (298) Baptistina, and not the K/T-impactor-size BAF members with D 10 km. Using WISE albedos, Sloan colors and newly obtained spectroscopic observations of BAF members, here we show that (1) the large objects in the BAF are mostly BAF interlopers, (2) that BAF has an homogeneous composition consistent with an X-type class. We discuss the implications of the link between the BAF and the K/T impactor.

Aerosol Sampling: Comparison of Two Rotating Impactors for Field Droplet Sizing and Volumetric Measurements

DTIC Science & Technology

2009-01-01

the rotating impactors were measured via spectroscopy and microscopy. The rotary impactors were colocated with an isokinetic air sampler for a total...diameter, and the 90% diameter (DV10 and DV90; ASTM 2004). For each replication, an isokinetic air sampler and rotary sampler operated simultaneously in the...working area of the dispersion tunnel. The isokinetic sampler (StaplexH Model TFIA High Volume Air Sampler, The Staplex Company, Brooklyn, NY) was

The ISIS Mission Concept: An Impactor for Surface and Interior Science

NASA Technical Reports Server (NTRS)

Chesley, Steven R.; Elliot, John O.; Abell, Paul A.; Asphaug, Erik; Bhaskaran, Shyam; Lam, Try; Lauretta, Dante S.

2013-01-01

The Impactor for Surface and Interior Science (ISIS) mission concept is a kinetic asteroid impactor mission to the target of NASA's OSIRIS-REx (Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer) asteroid sample return mission. The ISIS mission concept calls for the ISIS spacecraft, an independent and autonomous smart impactor, to guide itself to a hyper-velocity impact with 1999 RQ36 while the OSIRIS-REx spacecraft observes the collision. Later the OSIRIS-REx spacecraft descends to reconnoiter the impact site and measure the momentum imparted to the asteroid through the impact before departing on its journey back to Earth. In this paper we discuss the planetary science, human exploration and impact mitigation drivers for mission, and we describe the current mission concept and flight system design.

Proton-Induced X-Ray Emission Analysis of Crematorium Emissions

NASA Astrophysics Data System (ADS)

Ali, Salina; Nadareski, Benjamin; Yoskowitz, Joshua; Labrake, Scott; Vineyard, Michael

2014-09-01

There has been considerable debate in recent years about possible mercury emissions from crematoria due to amalgam tooth restorations. We have performed a proton-induced X-ray emission (PIXE) analysis of aerosol and soil samples taken near the Vale Cemetery Crematorium in Schenectady, NY, to address this concern. The aerosol samples were collected on the roof of the crematorium using a nine-stage, cascade impactor that separates the particulate matter by aerodynamic diameter and deposits it onto thin Kapton foils. The soil samples were collected at several different distances from the crematorium and compressed into pellets with a hydraulic press. The Kapton foils containing the aerosol samples and the soil pellets were bombarded with 2.2-MeV protons from the 1.1-MV tandem Pelletron accelerator in the Union College Ion-Beam Analysis Laboratory. We measured significant concentrations of sulfur, phosphorus, potassium, calcium, and iron, but essentially no mercury in the aerosol samples. The lower limit of detection for airborne mercury in this experiment was approximately 0.2 ng / m3. The PIXE analysis of the soil samples showed the presence of elements commonly found in soil (Si, K, Ca, Ti, Mn, Fe), but no trace of mercury. There has been considerable debate in recent years about possible mercury emissions from crematoria due to amalgam tooth restorations. We have performed a proton-induced X-ray emission (PIXE) analysis of aerosol and soil samples taken near the Vale Cemetery Crematorium in Schenectady, NY, to address this concern. The aerosol samples were collected on the roof of the crematorium using a nine-stage, cascade impactor that separates the particulate matter by aerodynamic diameter and deposits it onto thin Kapton foils. The soil samples were collected at several different distances from the crematorium and compressed into pellets with a hydraulic press. The Kapton foils containing the aerosol samples and the soil pellets were bombarded with 2.2-MeV protons from the 1.1-MV tandem Pelletron accelerator in the Union College Ion-Beam Analysis Laboratory. We measured significant concentrations of sulfur, phosphorus, potassium, calcium, and iron, but essentially no mercury in the aerosol samples. The lower limit of detection for airborne mercury in this experiment was approximately 0.2 ng / m3. The PIXE analysis of the soil samples showed the presence of elements commonly found in soil (Si, K, Ca, Ti, Mn, Fe), but no trace of mercury. Union College Department of Physics and Astronomy.

Indoor and outdoor sources of size-resolved mass concentration of particulate matter in a school gym-implications for exposure of exercising children.

PubMed

Braniš, Martin; Safránek, Jiří; Hytychová, Adéla

2011-05-01

It has been noticed many times that schools are buildings with high levels of particulate matter concentrations. Several authors documented that concentrations of particulate matter in indoor school microenvironments exceed limits recommended by WHO namely when school buildings are situated near major roads with high traffic densities. In addition, exercise under conditions of high particulate concentrations may increase the adverse health effects, as the total particle deposition increases in proportion to minute ventilation, and the deposition fraction nearly doubles from rest to intense exercise. Mass concentrations of size-segregated aerosol were measured simultaneously in an elementary school gym and an adjacent outdoor site in the central part of Prague by two pairs of collocated aerosol monitors-a fast responding photometer DusTrak and a five stage cascade impactor. To encompass seasonal and annual differences, 89 days of measurements were performed during ten campaigns between 2005 and 2009. The average (all campaigns) outdoor concentration of PM(2.5) (28.3 μg m(-3)) measured by the cascade impactors was higher than the indoor value (22.3 μg m(-3)) and the corresponding average from the nearest fixed site monitor (23.6 μg m(-3)). Indoor and outdoor PM(2.5) concentrations exceeded the WHO recommended 24-h limit in 42% and 49% of the days measured, respectively. The correlation coefficient (r) between corresponding outdoor and indoor aerosol sizes increased with decreasing aerodynamic diameter of the collected particles (r = 0.32-0.87), suggesting a higher infiltration rate of fine and quasi-ultrafine particles. Principal component analysis revealed five factors explaining more than 82% of the data variability. The first two factors reflected a close association between outdoor and indoor fine and quasi-ultrafine particles confirming the hypothesis of high infiltration rate of particles from outdoors. The third factor indicated that human activity is the main source of indoor emission of coarse particles. The fourth factor involved only outdoor variables showing the resuspension of coarse ambient aerosol on dry and warm days without its seeming effect on the indoor coarse PM levels. Having in mind that high concentrations of both fine and coarse aerosol were frequently observed in the studied space, our results suggest that indoor exercise in polluted urbanized areas may increase the overall exposure and thus represent a potential health risk to young individuals during physical education at schools.

Disparities in Depressive Symptoms and Antidepressant Treatment by Gender and Race/Ethnicity among People Living with HIV in the United States.

PubMed

Bengtson, Angela M; Pence, Brian W; Crane, Heidi M; Christopoulos, Katerina; Fredericksen, Rob J; Gaynes, Bradley N; Heine, Amy; Mathews, W Christopher; Moore, Richard; Napravnik, Sonia; Safren, Steven; Mugavero, Michael J

2016-01-01

To describe disparities along the depression treatment cascade, from indication for antidepressant treatment to effective treatment, in HIV-infected individuals by gender and race/ethnicity. The Center for AIDS Research (CFAR) Network of Integrated Clinical Systems (CNICS) cohort includes 31,000 HIV-infected adults in routine clinical care at 8 sites. Individuals were included in the analysis if they had a depressive symptoms measure within one month of establishing HIV care at a CNICS site. Depressive symptoms were measured using the validated Patient Health Questionnaire-9 (PHQ-9). Indication for antidepressant treatment was defined as PHQ-9 ≥ 10 or a current antidepressant prescription. Antidepressant treatment was defined as a current antidepressant prescription. Evidence-based antidepressant treatment was considered treatment changes based on a person's most recent PHQ-9, in accordance with clinical guidelines. We calculated the cumulative probability of moving through the depression treatment cascade within 24 months of entering CNICS HIV care. We used multivariable Cox proportional hazards models to estimate associations between gender, race/ethnicity, and a range of depression outcomes. In our cohort of HIV-infected adults in routine care, 47% had an indication for antidepressant treatment. Significant drop-offs along the depression treatment cascade were seen for the entire study sample. However, important disparities existed. Women were more likely to have an indication for antidepressant treatment (HR 1.54; 95% CI 1.34, 1.78), receive antidepressant treatment (HR 2.03; 95% CI 1.53, 2.69) and receive evidence-based antidepressant treatment (HR 1.67; 95% CI 1.03, 2.74), even after accounting for race/ethnicity. Black non-Hispanics (HR 0.47, 95% CI 0.35, 0.65), Hispanics (HR 0.63, 95% CI 0.44, 0.89) and other race/ethnicities (HR 0.35, 95% CI 0.17, 0.73) were less likely to initiate antidepressant treatment, compared to white non-Hispanics. In our cohort of HIV-infected adults depressive symptoms were common. Important disparities in the prevalence of depressive symptoms and receipt of antidepressant treatment existed by gender and race/ethnicity.

Is substance use associated with HIV cascade outcomes in Latin America?

PubMed Central

Peratikos, Meridith B.; Shepherd, Bryan E.; Grinsztejn, Beatriz; Cortés, Claudia; Padgett, Denis; Gotuzzo, Eduardo; Belaunzarán-Zamudio, Pablo F.; Rebeiro, Peter F.; Duda, Stephany N.; McGowan, Catherine C.

2018-01-01

Background The HIV care cascade has improved in Latin America over the last decade. However, the influence of alcohol and noninjected drug use (NIDU) on cascade outcomes is mostly unknown. This study estimated the association of alcohol and NIDU with retention in care, loss to follow up (LTFU), and virologic failure (VF). Methods Individuals ≥18 years attending routine HIV clinic visits and completing the Rapid Screening Tool (RST; evaluating NIDU and ART adherence in 7-day recall period) during 2012–13 were followed up to 2015 in the Caribbean, Central and South America network for HIV epidemiology. Adjusted odds ratios (aOR) were calculated for the association of alcohol consumption and NIDU with retention in care by logistic regression; adjusted hazard ratios (aHR) were estimated for the associations with LTFU and VF by Cox regression. Results Among 3604 individuals, the proportions retained in care for one year were 84%, 79%, 72%, and 69% for patients reporting non-use, alcohol use, NIDU, and both alcohol and NIDU, respectively. For the same patient groups, the proportions LTFU over 18 months were 6%, 8%, 12%, and 13%, respectively. There were 1901 patients (53%) with HIV RNA results; VF proportions were similar between users and nonusers (ranging from 14–16%). After controlling for age, sex, study site, HIV transmission mode, time on ART, AIDS status, and CD4 count, neither alcohol use (aOR = 1.1, CI = 0.9–1.4; aHR = 1.0, CI = 0.8–1.3) nor NIDU (aOR = 1.3, CI = 0.9–1.8; aHR = 1.4, CI = 0.9–2.1) were significantly associated with retention or VF, respectively. However, both alcohol use (aHR = 1.2, CI = 1.02–1.4) and NIDU (aHR = 1.3, CI = 1.00–1.8) were associated with increased LTFU. Conclusion Alcohol use and NIDU in a 7-day recall period increased the risk of being LTFU during the next 18 months, highlighting the need for routine screening and targeted interventions to keep these individuals in care and on ART. PMID:29543857

Dark-ray and dark-floor craters on Ganymede, and the provenance of large impactors in the Jovian system

NASA Technical Reports Server (NTRS)

Schenk, Paul M.; Mckinnon, William B.

1991-01-01

The dark-floor and dark-ray craters on the icy Jovian satellite, Ganymede, may derive their visual characteristics from impactor contamination. It is presently hypothesized that the rays darken as a result of the near-surface concentration of impactor material; this could occur, first, due to magnetic sputtering while the rays are bright, and subsequently, once a critical albedo is reached, due to thermal sublimation into discrete icy and nonicy patches. Voyager visible spectra of dark rays indicate that most large-ray systems are 'redder' than grooved or cratered terrains, and are among the 'reddest' units on Ganymede. More than half of the recent impactors on Ganymede may have been reddish D-type asteroids or comets, accounting for the albedos and colors of dark terrains on both Ganymede and Callisto.

A Game of Space Telephone

NASA Image and Video Library

2006-10-19

This image shows NASA Deep Impact spacecraft being built at Ball Aerospace & Technologies Corporation, Boulder, Colo. On July 2, 2005. The impactor S-band antenna is the rectangle-shaped object seen on the top of the impactor.

Delaminations in composite plates under transverse impact loads - Experimental results

NASA Technical Reports Server (NTRS)

Finn, Scott R.; He, Ye-Fei; Springer, George S.

1993-01-01

Tests were performed measuring the locations and geometries of delaminations in Fiberite T300/976 graphite/epoxy, Fiberite IM7/977-2 graphite-toughened epoxy, and ICI APC-2 graphite/PEEK plates subjected to transverse impact loads. The data provide specific information on the effects of impactor velocity, impactor mass, material, thickness of back ply group, difference in fiber orientation between adjacent ply groups, plate thickness, and impactor nose radius. The data were compared to the results of the Finn-Springer model. The model was found to describe the data with reasonable accuracy.

A space mission to detect imminent Earth impactors

NASA Astrophysics Data System (ADS)

Valsecchi, G. B.; Perozzi, E.; Rossi, A.

2015-03-01

One of the goals of NEO surveys is to discover Earth impactors before they hit. How much warning time is desirable depends on the size of the impactors: for the larger ones more time is needed to mount effective mitigation measures. Initially, NEO surveys were aimed at large impactors, that can have significant global effects; however, their typical time scale is orders of magnitude larger than human lifetime. At the other extreme, monthly and annual events, liberating energies of the order of 1 to 10 kilotons, are immaterial as a threat to mankind, not justifying substantial expenditure on them. Intermediate events are of more concern: in the megatons range, timescales are of the order of centuries, and the damage can be substantial. A classical example is the Tunguska event, in which a body with a diameter of about 30 to 50 m liberated about 5 megatons in the atmosphere, devastating 2 000 square kilometers of Siberian forest.

Osmium, tungsten, and chromium isotopes in sediments and in Ni-rich spinel at the K-T boundary: Signature of a chondritic impactor

NASA Astrophysics Data System (ADS)

Quitté, Ghylaine; Robin, Eric; Levasseur, Sylvain; Capmas, Françoise; Rocchia, Robert; Birck, Jean-Louis; Allègre, Claude Jean

It is now established that a large extraterrestrial object hit the Earth at the end of the Cretaceous period, about 65 Ma ago. We have investigated Re-Os, Hf-W, and Mn-Cr isotope systems in sediments from the Cretaceous and the Paleogene in order to characterize the type of impactor. Within the Cretaceous-Tertiary (K-T) boundary layer, extraterrestrial material is mixed with terrestrial material, causing a dilution of the extraterrestrial isotope signature that is difficult to quantify. A phase essentially composed of Ni-rich spinel, formed in the atmosphere mainly from melted projectile material, is likely to contain the extraterrestrial isotopic signature of the impactor. We show that the analysis of spinel is indeed the best approach to determine the initial isotope composition of the impactor, and that W and Cr isotopes confirm that the projectile was a carbonaceous chondrite.

Virtual Impactor for Sub-micron Aerosol Particles

NASA Astrophysics Data System (ADS)

Bolshakov, A. A.; Strawa, A. W.; Hallar, A. G.

2005-12-01

The objective of a virtual impactor is to separate out the larger particles in a flow from the smaller particles in such a way that both sizes of particles are available for sampling. A jet of particle-laden air is accelerated toward a collection probe so that a small gap exists between the acceleration nozzle and the probe. A vacuum is applied to deflect a major portion of the airstream away form the collection probe. Particles larger than a certain size have sufficient momentum so that they cross the deflected streamlines and enter the collection probe, whereas smaller particles follow the deflected streamlines. The result is that the collection probe will contain a higher concentration of larger particles than is in the initial airstream. Typically, virtual impactors are high-flow devices used to separate out particles greater than several microns in diameter. We have developed a special virtual impactor to concentrate aerosol particles of diameters between 0.5 to 1 micron for the purpose of calibrating the optical cavity ring-down instrument [1]. No similar virtual impactors are commercially available. In our design, we have exploited considerations described earlier [2-4]. Performance of our virtual impactor was evaluated in an experimental set-up using TSI 3076 nebulizer and TSI 3936 scanning mobility particle size spectrometer. Under experimental conditions optimized for the best performance of the virtual impactor, we were able to concentrate the 700-nm polystyrene particles no less than 15-fold. However, under experimental conditions optimized for calibrating our cavity ring-down instrument, a concentration factor attainable was from 4 to 5. During calibration experiments, maximum realized particle number densities were 190, 300 and 1600 cm-3 for the 900-nm, 700-nm and 500-nm spheres, respectively. This paper discusses the design of the impactor and laboratory studies verifying its performance. References: 1. A.W. Strawa, R. Castaneda, T. Owano, D.S. Baer, B.A. Paldus, J. Atm. Ocean. Technol., 20, 454-465 (2003). 2. V.A. Marple, K.L. Rubow, B.A. Olson, Aerosol Sci. Technol., 22, 140-150 (1995). 3. B.T. Chen, H.C. Yeh, Y.S. Cheng, J. Aerosol Sci., 16, 343-354 (1985). 4. V.A. Marple, C.M. Chien, Environ. Sci. Technol., 14, 976-985 (1980).

Experimental Characterization of Microfabricated VirtualImpactor Efficiency

EPA Science Inventory

The Air-Microfluidics Group is developing a microelectromechanical systems-based direct reading particulate matter (PM) mass sensor. The sensor consists of two main components: a microfabricated virtual impactor (VI) and a PM mass sensor. The VI leverages particle inertia to sepa...

49 CFR 571.226 - Standard No. 226; Ejection Mitigation.

Code of Federal Regulations, 2011 CFR

2011-10-01

... plywood with a minimum thickness of 18 mm as a reaction surface on the opposite side of the glazing to... attached to the impactor with its center of gravity passing through the axis of motion of the impactor and...

The impactor flux in the Pluto-Charon system

NASA Technical Reports Server (NTRS)

Weissman, Paul R.; Stern, S. Alan

1994-01-01

Current impact rates of comets on Pluto and Charon are estimated. It is shown that the dominant sources of impactors are comets from the Kuiper belt and the inner Oort cloud, each of whose perihelion distribution extends across Pluto's orbit. In contrast, long-period comets from the outer Oort cloud are a negligible source of impactors. The total predicted number of craters is not sufficient to saturate the surface areas of either Pluto of Charon over the age of the Solar System. However, heavy cratering may have occurred early in the Solar System's history during clearing of planetesimals from the outer planets' zone.

Particle impactor assembly for size selective high volume air sampler

DOEpatents

Langer, Gerhard

1988-08-16

Air containing entrained particulate matter is directed through a plurality of parallel, narrow, vertically oriented impactor slots of an inlet element toward an adjacently located, relatively large, dust impaction surface preferably covered with an adhesive material. The air flow turns over the impaction surface, leaving behind the relatively larger particles according to the human thoracic separation system and passes through two elongate exhaust apertures defining the outer bounds of the impaction collection surface to pass through divergent passages which slow down and distribute the air flow, with entrained smaller particles, over a fine filter element that separates the fine particles from the air. The elongate exhaust apertures defining the impaction collection surface are spaced apart by a distance greater than the lengths of elongate impactor slots in the inlet element and are oriented to be normal thereto. By appropriate selection of dimensions and the number of impactor slots air flow through the inlet element is provided a nonuniform velocity distribution with the lower velocities being obtained near the center of the impactor slots, in order to separate out particles larger than a certain predetermined size on the impaction collection surface. The impaction collection surface, even in a moderately sized apparatus, is thus relatively large and permits the prolonged sampling of air for periods extending to four weeks.

Comparative particle recoveries by the retracting rotorod, rotoslide and Burkard spore trap sampling in a compact array

NASA Astrophysics Data System (ADS)

Solomon, W. R.; Burge, H. A.; Boise, J. R.; Becker, M.

1980-06-01

An array comprising 4 intermittent (retracting) rotorods, 3 (“swingshield”) rotoslides and one Burkard (Hirst) automatic volumetric spore trap was operated on an urban rooftop during 70 periods of 9, 15 or 24 hours in late summer. Standard sampling procedures were utilized and recoveries of pollens as well as spores of Alternaria, Epicoccum, Pithomyces and Ganoderma species compared. Differences between paired counts from each sampler type showed variances increasing with levels of particle prevalence (and deposition). In addition, minimal, non-random, side-to-side and intersampler differences were noted for both impactor types. Exclusion of particles between operating intervals by rotoslides and rotorods was virtually complete. Spore trap recoveries for all particle categories, per m3, exceeded those by both impactors. The greatest (7-fold) difference was noted for the smallest type examined ( Ganoderma). For ragweed pollen, an overall spore trap/impactor ratio approached 1.5. Rain effects were difficult to discern but seemed to influence rotoslides least. Overall differences between impactors were quite small but generally favored the rotoslide in this comparison. Our data confirm the relative advantages of suction traps for small particles. Both impactors and spore traps are suited to pollen and large spore collection, and, with some qualification, data from both may be compared.

New Insight into Short-Wavelength Solar Wind Fluctuations from Vlasov Theory

NASA Technical Reports Server (NTRS)

Sahraoui, Fouad; Belmont, G.; Goldstein, M. L.

2012-01-01

The nature of solar wind (SW) turbulence below the proton gyroscale is a topic that is being investigated extensively nowadays, both theoretically and observationally. Although recent observations gave evidence of the dominance of kinetic Alfven waves (KAWs) at sub-ion scales with omega < omega(sub ci), other studies suggest that the KAW mode cannot carry the turbulence cascade down to electron scales and that the whistler mode (i.e., omega > omega (sub ci)) is more relevant. Here, we study key properties of the short-wavelength plasma modes under limited, but realistic, SW conditions, Typically Beta(sub i) approx. > Beta (sub e) 1 and for high oblique angles of propagation 80 deg <= Theta (sub kB) < 90 deg as observed from the Cluster spacecraft data. The linear properties of the plasma modes under these conditions are poorly known, which contrasts with the well-documented cold plasma limit and/or moderate oblique angles of propagation (Theta (sub kB) < 80 deg). Based on linear solutions of the Vlasov kinetic theory, we discuss the relevance of each plasma mode (fast, Bernstein, KAW, whistler) in carrying the energy cascade down to electron scales. We show, in particular, that the shear Alfven mode (known in the magnetohydrodynamic limit) extends at scales kappa rho (sub i) approx. > 1 to frequencies either larger or smaller than omega (sub ci), depending on the anisotropy kappa (parallel )/ kappa(perpendicular). This extension into small scales is more readily called whistler (omega > omega (sub ci)) or KAW (omega < omega (sub ci)) although the mode is essentially the same. This contrasts with the well-accepted idea that the whistler branch always develops as a continuation at high frequencies of the fast magnetosonic mode. We show, furthermore, that the whistler branch is more damped than the KAW one, which makes the latter the more relevant candidate to carry the energy cascade down to electron scales. We discuss how these new findings may facilitate resolution of the controversy concerning the nature of the small-scale turbulence, and we discuss the implications for present and future spacecraft wave measurements in the SW.

PIXE Analysis of Atmospheric Aerosol Samples Collected in the Adirondack Mountains

NASA Astrophysics Data System (ADS)

Yoskowitz, Josh; Ali, Salina; Nadareski, Benjamin; Safiq, Alexandrea; Smith, Jeremy; Labrake, Scott; Vineyard, Michael

2013-10-01

We have performed an elemental analysis of atmospheric aerosol samples collected at Piseco Lake in Upstate New York using proton induced x-ray emission spectroscopy (PIXE). This work is part of a systematic study of airborne pollution in the Adirondack Mountains. Of particular interest is the sulfur content that can contribute to acid rain, a well-documented problem in the Adirondacks. We used a nine-stage cascade impactor to collect the samples and distribute the particulate matter onto Kapton foils by particle size. The PIXE experiments were performed with 2.2-MeV proton beams from the 1.1-MV pelletron accelerator in the Union College Ion-Beam Analysis Laboratory. X-Ray energy spectra were measured with a silicon drift detector and analyzed with GUPIX software to determine the elemental concentrations of the aerosols. A broad range of elements from silicon to zinc were detected with significant sulfur concentrations measured for particulate matter between 0.25 and 0.5 μm in size. The PIXE analysis will be described and preliminary results will be presented.

Environmental health hazards of e-cigarettes and their components: Oxidants and copper in e-cigarette aerosols.

PubMed

Lerner, Chad A; Sundar, Isaac K; Watson, Richard M; Elder, Alison; Jones, Ryan; Done, Douglas; Kurtzman, Rachel; Ossip, Deborah J; Robinson, Risa; McIntosh, Scott; Rahman, Irfan

2015-03-01

To narrow the gap in our understanding of potential oxidative properties associated with Electronic Nicotine Delivery Systems (ENDS) i.e. e-cigarettes, we employed semi-quantitative methods to detect oxidant reactivity in disposable components of ENDS/e-cigarettes (batteries and cartomizers) using a fluorescein indicator. These components exhibit oxidants/reactive oxygen species reactivity similar to used conventional cigarette filters. Oxidants/reactive oxygen species reactivity in e-cigarette aerosols was also similar to oxidant reactivity in cigarette smoke. A cascade particle impactor allowed sieving of a range of particle size distributions between 0.450 and 2.02 μm in aerosols from an e-cigarette. Copper, being among these particles, is 6.1 times higher per puff than reported previously for conventional cigarette smoke. The detection of a potentially cytotoxic metal as well as oxidants from e-cigarette and its components raises concern regarding the safety of e-cigarettes use and the disposal of e-cigarette waste products into the environment. Copyright © 2014 Elsevier Ltd. All rights reserved.

Catastrophic Disruption Threshold and Maximum Deflection from Kinetic Impact

NASA Astrophysics Data System (ADS)

Cheng, A. F.

2017-12-01

The use of a kinetic impactor to deflect an asteroid on a collision course with Earth was described in the NASA Near-Earth Object Survey and Deflection Analysis of Alternatives (2007) as the most mature approach for asteroid deflection and mitigation. The NASA DART mission will demonstrate asteroid deflection by kinetic impact at the Potentially Hazardous Asteroid 65803 Didymos in October, 2022. The kinetic impactor approach is considered to be applicable with warning times of 10 years or more and with hazardous asteroid diameters of 400 m or less. In principle, a larger kinetic impactor bringing greater kinetic energy could cause a larger deflection, but input of excessive kinetic energy will cause catastrophic disruption of the target, leaving possibly large fragments still on collision course with Earth. Thus the catastrophic disruption threshold limits the maximum deflection from a kinetic impactor. An often-cited rule of thumb states that the maximum deflection is 0.1 times the escape velocity before the target will be disrupted. It turns out this rule of thumb does not work well. A comparison to numerical simulation results shows that a similar rule applies in the gravity limit, for large targets more than 300 m, where the maximum deflection is roughly the escape velocity at momentum enhancement factor β=2. In the gravity limit, the rule of thumb corresponds to pure momentum coupling (μ=1/3), but simulations find a slightly different scaling μ=0.43. In the smaller target size range that kinetic impactors would apply to, the catastrophic disruption limit is strength-controlled. A DART-like impactor won't disrupt any target asteroid down to significantly smaller size than the 50 m below which a hazardous object would not penetrate the atmosphere in any case unless it is unusually strong.

In Vitro Comparison of Aerosol Delivery Using Different Face Masks and Flow Rates With a High-Flow Humidity System.

PubMed

Lin, Hui-Ling; Harwood, Robert J; Fink, James B; Goodfellow, Lynda T; Ari, Arzu

2015-09-01

Aerosol drug delivery to infants and small children is influenced by many factors, such as types of interface, gas flows, and the designs of face masks. The purpose of this in vitro study was to evaluate aerosol delivery during administration of gas flows across the range used clinically with high-flow humidity systems using 2 aerosol masks. A spontaneous lung model was used to simulate an infant/young toddler up to 2 y of age and pediatric breathing patterns. Nebulized salbutamol by a vibrating mesh nebulizer positioned at the inlet of a high-flow humidification system at gas flows of 3, 6, and 12 L/min was delivered via pediatric face masks to a pediatric face mannequin attached to a filter. Aerosol particle size distribution exiting the vibrating mesh nebulizer and at the mask position distal to the heated humidifier with 3 flows was measured with a cascade impactor. Eluted drug from the filters and the impactor was analyzed with a spectrophotometer (n = 3). Statistical analysis was performed by analysis of variance with a significant level of P < .05. The inhaled mass was between 2.8% and 8.1% among all settings and was significantly lower at 12 L/min (P = .004) in the pediatric model. Drug delivery with pediatric breathing was greater than with infant breathing (P = .004). The particle size distribution of aerosol emitted from the nebulizer was larger than the heated humidified aerosol exiting the tubing (P = .002), with no difference between the 3 flows (P = .10). The flows of gas entering the mask and breathing patterns influence aerosol delivery, independent of the face mask used. Aerosol delivery through a high-flow humidification system via mask could be effective with both infant and pediatric breathing patterns. Copyright © 2015 by Daedalus Enterprises.

In vitro dose comparison of Respimat® inhaler with dry powder inhalers for COPD maintenance therapy.

PubMed

Ciciliani, Anna-Maria; Langguth, Peter; Wachtel, Herbert

2017-01-01

Combining in vitro mouth-throat deposition measurements, cascade impactor data and computational fluid dynamics (CFD) simulations, four different inhalers were compared which are indicated for chronic obstructive pulmonary disease (COPD) treatment. The Respimat inhaler, the Breezhaler, the Genuair, and the Ellipta were coupled to the idealized Alberta throat model. The modeled dose to the lung (mDTL) was collected downstream of the Alberta throat model using either a filter or a next generation impactor (NGI). Idealized breathing patterns from COPD patient groups - moderate and very severe COPD - were applied. Theoretical lung deposition patterns were assessed by an individual path model. For the Respimat the mDTL was found to be 59% (SD 5%) for the moderate COPD breathing pattern and 67% (SD 5%) for very severe COPD breathing pattern. The percentages refer to nominal dose (ND) in vitro. This is in the range of 44%-63% in vivo in COPD patients who display large individual variability. Breezhaler showed a mDTL of 43% (SD 2%) for moderate disease simulation and 51% (SD 2%) for very severe simulation. The corresponding results for Genuair are mDTL of 32% (SD 2%) for moderate and 42% (SD 1%) for very severe disease. Ellipta vilanterol particles showed a mDTL of 49% (SD 3%) for moderate and 55% (SD 2%) for very severe disease simulation, and Ellipta fluticasone particles showed a mDTL of 33% (SD 3%) and 41% (SD 2%), respectively for the two breathing patterns. Based on the throat output and average flows of the different inhalers, CFD simulations were performed. Laminar and turbulent steady flow calculations indicated that deposition occurs mainly in the small airways. In summary, Respimat showed the lowest amount of particles depositing in the mouth-throat model and the highest amount reaching all regions of the simulation lung model.

Organic speciation of size-segregated atmospheric particulate matter

NASA Astrophysics Data System (ADS)

Tremblay, Raphael

Particle size and composition are key factors controlling the impacts of particulate matter (PM) on human health and the environment. A comprehensive method to characterize size-segregated PM organic content was developed, and evaluated during two field campaigns. Size-segregated particles were collected using a cascade impactor (Micro-Orifice Uniform Deposit Impactor) and a PM2.5 large volume sampler. A series of alkanes and polycyclic aromatic hydrocarbons (PAHs) were solvent extracted and quantified using a gas chromatograph coupled with a mass spectrometer (GC/MS). Large volume injections were performed using a programmable temperature vaporization (PTV) inlet to lower detection limits. The developed analysis method was evaluated during the 2001 and 2002 Intercomparison Exercise Program on Organic Contaminants in PM2.5 Air Particulate Matter led by the US National Institute of Standards and Technology (NIST). Ambient samples were collected in May 2002 as part of the Tampa Bay Regional Atmospheric Chemistry Experiment (BRACE) in Florida, USA and in July and August 2004 as part of the New England Air Quality Study - Intercontinental Transport and Chemical Transformation (NEAQS - ITCT) in New Hampshire, USA. Morphology of the collected particles was studied using scanning electron microscopy (SEM). Smaller particles (one micrometer or less) appeared to consist of solid cores surrounded by a liquid layer which is consistent with combustion particles and also possibly with particles formed and/or coated by secondary material like sulfate, nitrate and secondary organic aerosols. Source apportionment studies demonstrated the importance of stationary sources on the organic particulate matter observed at these two rural sites. Coal burning and biomass burning were found to be responsible for a large part of the observed PAHs during the field campaigns. Most of the measured PAHs were concentrated in particles smaller than one micrometer and linked to combustion sources. The presence of known carcinogenic PAHs in the respirable particles has strong importance for human health. Recommendations for method improvements and further studies are included.

In vitro dose comparison of Respimat® inhaler with dry powder inhalers for COPD maintenance therapy

PubMed Central

Ciciliani, Anna-Maria; Langguth, Peter; Wachtel, Herbert

2017-01-01

Background Combining in vitro mouth–throat deposition measurements, cascade impactor data and computational fluid dynamics (CFD) simulations, four different inhalers were compared which are indicated for chronic obstructive pulmonary disease (COPD) treatment. Methods The Respimat inhaler, the Breezhaler, the Genuair, and the Ellipta were coupled to the idealized Alberta throat model. The modeled dose to the lung (mDTL) was collected downstream of the Alberta throat model using either a filter or a next generation impactor (NGI). Idealized breathing patterns from COPD patient groups – moderate and very severe COPD – were applied. Theoretical lung deposition patterns were assessed by an individual path model. Results and conclusion For the Respimat the mDTL was found to be 59% (SD 5%) for the moderate COPD breathing pattern and 67% (SD 5%) for very severe COPD breathing pattern. The percentages refer to nominal dose (ND) in vitro. This is in the range of 44%–63% in vivo in COPD patients who display large individual variability. Breezhaler showed a mDTL of 43% (SD 2%) for moderate disease simulation and 51% (SD 2%) for very severe simulation. The corresponding results for Genuair are mDTL of 32% (SD 2%) for moderate and 42% (SD 1%) for very severe disease. Ellipta vilanterol particles showed a mDTL of 49% (SD 3%) for moderate and 55% (SD 2%) for very severe disease simulation, and Ellipta fluticasone particles showed a mDTL of 33% (SD 3%) and 41% (SD 2%), respectively for the two breathing patterns. Based on the throat output and average flows of the different inhalers, CFD simulations were performed. Laminar and turbulent steady flow calculations indicated that deposition occurs mainly in the small airways. In summary, Respimat showed the lowest amount of particles depositing in the mouth–throat model and the highest amount reaching all regions of the simulation lung model. PMID:28603412

The Tuberculosis Cascade of Care in India’s Public Sector: A Systematic Review and Meta-analysis

PubMed Central

Satyanarayana, Srinath; Pai, Madhukar; Thomas, Beena E.; Chadha, Vineet K.; Swaminathan, Soumya; Mayer, Kenneth H.

2016-01-01

Background India has 23% of the global burden of active tuberculosis (TB) patients and 27% of the world’s “missing” patients, which includes those who may not have received effective TB care and could potentially spread TB to others. The “cascade of care” is a useful model for visualizing deficiencies in case detection and retention in care, in order to prioritize interventions. Methods and Findings The care cascade constructed in this paper focuses on the Revised National TB Control Programme (RNTCP), which treats about half of India’s TB patients. We define the TB cascade as including the following patient populations: total prevalent active TB patients in India, TB patients who reach and undergo evaluation at RNTCP diagnostic facilities, patients successfully diagnosed with TB, patients who start treatment, patients retained to treatment completion, and patients who achieve 1-y recurrence-free survival. We estimate each step of the cascade for 2013 using data from two World Health Organization (WHO) reports (2014–2015), one WHO dataset (2015), and three RNTCP reports (2014–2016). In addition, we conduct three targeted systematic reviews of the scientific literature to identify 39 unique articles published from 2000–2015 that provide additional data on five indicators that help estimate different steps of the TB cascade. We construct separate care cascades for the overall population of patients with active TB and for patients with specific forms of TB—including new smear-positive, new smear-negative, retreatment smear-positive, and multidrug-resistant (MDR) TB. The WHO estimated that there were 2,700,000 (95%CI: 1,800,000–3,800,000) prevalent TB patients in India in 2013. Of these patients, we estimate that 1,938,027 (72%) TB patients were evaluated at RNTCP facilities; 1,629,906 (60%) were successfully diagnosed; 1,417,838 (53%) got registered for treatment; 1,221,764 (45%) completed treatment; and 1,049,237 (95%CI: 1,008,775–1,083,243), or 39%, of 2,700,000 TB patients achieved the optimal outcome of 1-y recurrence-free survival. The separate cascades for different forms of TB highlight different patterns of patient attrition. Pretreatment loss to follow-up of diagnosed patients and post-treatment TB recurrence were major points of attrition in the new smear-positive TB cascade. In the new smear-negative and MDR TB cascades, a substantial proportion of patients who were evaluated at RNTCP diagnostic facilities were not successfully diagnosed. Retreatment smear-positive and MDR TB patients had poorer treatment outcomes than the general TB population. Limitations of our analysis include the lack of available data on the cascade of care in the private sector and substantial uncertainty regarding the 1-y period prevalence of TB in India. Conclusions Increasing case detection is critical to improving outcomes in India’s TB cascade of care, especially for smear-negative and MDR TB patients. For new smear-positive patients, pretreatment loss to follow-up and post-treatment TB recurrence are considerable points of attrition that may contribute to ongoing TB transmission. Future multisite studies providing more accurate information on key steps in the public sector TB cascade and extension of this analysis to private sector patients may help to better target interventions and resources for TB control in India. PMID:27780217

The Tuberculosis Cascade of Care in India's Public Sector: A Systematic Review and Meta-analysis.

PubMed

Subbaraman, Ramnath; Nathavitharana, Ruvandhi R; Satyanarayana, Srinath; Pai, Madhukar; Thomas, Beena E; Chadha, Vineet K; Rade, Kiran; Swaminathan, Soumya; Mayer, Kenneth H

2016-10-01

India has 23% of the global burden of active tuberculosis (TB) patients and 27% of the world's "missing" patients, which includes those who may not have received effective TB care and could potentially spread TB to others. The "cascade of care" is a useful model for visualizing deficiencies in case detection and retention in care, in order to prioritize interventions. The care cascade constructed in this paper focuses on the Revised National TB Control Programme (RNTCP), which treats about half of India's TB patients. We define the TB cascade as including the following patient populations: total prevalent active TB patients in India, TB patients who reach and undergo evaluation at RNTCP diagnostic facilities, patients successfully diagnosed with TB, patients who start treatment, patients retained to treatment completion, and patients who achieve 1-y recurrence-free survival. We estimate each step of the cascade for 2013 using data from two World Health Organization (WHO) reports (2014-2015), one WHO dataset (2015), and three RNTCP reports (2014-2016). In addition, we conduct three targeted systematic reviews of the scientific literature to identify 39 unique articles published from 2000-2015 that provide additional data on five indicators that help estimate different steps of the TB cascade. We construct separate care cascades for the overall population of patients with active TB and for patients with specific forms of TB-including new smear-positive, new smear-negative, retreatment smear-positive, and multidrug-resistant (MDR) TB. The WHO estimated that there were 2,700,000 (95%CI: 1,800,000-3,800,000) prevalent TB patients in India in 2013. Of these patients, we estimate that 1,938,027 (72%) TB patients were evaluated at RNTCP facilities; 1,629,906 (60%) were successfully diagnosed; 1,417,838 (53%) got registered for treatment; 1,221,764 (45%) completed treatment; and 1,049,237 (95%CI: 1,008,775-1,083,243), or 39%, of 2,700,000 TB patients achieved the optimal outcome of 1-y recurrence-free survival. The separate cascades for different forms of TB highlight different patterns of patient attrition. Pretreatment loss to follow-up of diagnosed patients and post-treatment TB recurrence were major points of attrition in the new smear-positive TB cascade. In the new smear-negative and MDR TB cascades, a substantial proportion of patients who were evaluated at RNTCP diagnostic facilities were not successfully diagnosed. Retreatment smear-positive and MDR TB patients had poorer treatment outcomes than the general TB population. Limitations of our analysis include the lack of available data on the cascade of care in the private sector and substantial uncertainty regarding the 1-y period prevalence of TB in India. Increasing case detection is critical to improving outcomes in India's TB cascade of care, especially for smear-negative and MDR TB patients. For new smear-positive patients, pretreatment loss to follow-up and post-treatment TB recurrence are considerable points of attrition that may contribute to ongoing TB transmission. Future multisite studies providing more accurate information on key steps in the public sector TB cascade and extension of this analysis to private sector patients may help to better target interventions and resources for TB control in India.

Imparting Barely Visible Impact Damage to a Stitched Composite Large-Scale Pressure Box

NASA Technical Reports Server (NTRS)

Lovejoy, Andrew E.; Przekop, Adam

2016-01-01

The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) is a concept that was developed by The Boeing Company to address the complex structural design aspects associated with a pressurized hybrid wing body (HWB) aircraft configuration, which has been a focus of the NASA Environmentally Responsible Aviation Project. The NASA-Boeing structural development for the HWB aircraft culminated in testing of the multi-bay box, which is an 80%-scale representation of the pressurized center-body section. This structure was tested in the NASA Langley Research Center Combined Loads Test System facility. As part of this testing, barely visible impact damage was imparted to the interior and exterior of the test article to demonstrate compliance with a condition representative of the requirements for Category 1 damaged composite structure as defined by the Federal Aviation Regulations. Interior impacts were imparted using an existing spring-loaded impactor, while the exterior impacts were imparted using a newly designed, gravity-driven impactor. This paper describes the impacts to the test article, and the design of the gravitydriven guided-weight impactor. The guided-weight impactor proved to be a very reliable method to impart barely visible impact damage in locations which are not easily accessible for a traditional drop-weight impactor, while at the same time having the capability to be highly configurable for use on other aircraft structures.

Heavy metal toxicity as a kill mechanism in impact caused mass extinctions

NASA Technical Reports Server (NTRS)

Wdowiak, T. J.; Davenport, S. A.; Jones, D. D.; Wdowiak, P.

1988-01-01

Heavy metals that are known to be toxic exist in carbonaceous chrondrites at abundances considerably in excess to that of the terrestrial crust. An impactor of relatively undifferentiated cosmic matter would inject into the terrestrial environment large quantities of toxic elements. The abundances of toxic metals found in the Allende CV carbonaceous chondrite and the ratio of meteoritic abundance to crustal abundance are: Cr, 3630 PPM, 30X; Co, 662 PPM, 23X; ni, 13300 PPm, 134X; se, 8.2 PPM, 164X; Os, 0.828 PPM, 166X. The resulting areal density for global dispersal of impactor derived heavy metals and their dilution with terrestrial ejecta are important factors in the determination of the significance of impactor heavy metal toxicity as a kill mechanism in impact caused mass extinctions. A 10 km-diameter asteroid having a density of 3 gram per cu cm would yield a global areal density of impact dispersed chondritic material of 3 kg per square meter. The present areal density of living matter on the terrestrial land surface is 1 kg per square meter. Dilution of impactor material with terrestrial ejecta is determined by energetics, with the mass of ejecta estimated to be in the range of 10 to 100 times that of the mass of the impactor. Because a pelagic impact would be the most likely case, the result would be a heavy metal rainout.

A hybrid chip based on aerodynamics and electrostatics for the size-dependent classification of ultrafine and nano particles.

PubMed

Kim, Yong-Ho; Park, Dongho; Hwang, Jungho; Kim, Yong-Jun

2009-09-21

Conventional virtual impactors experience a large pressure drop when they classify particles according to size, in particular ultrafine particles smaller than 100 nm in diameter. Therefore, most virtual impactors have been used to classify particles larger than 100 nm. Their cut-off diameters are also fixed by the geometry of their flow channels. In the proposed virtual impactor, particles smaller than 100 nm are accelerated by applying DC potentials to an integrated electrode pair. By the electrical acceleration, the large pressure drop could be significantly decreased and new cut-off diameters smaller than 100 nm could be successfully added. The geometric cut-off diameter (GCD) of the proposed virtual impactor was designed to be 1.0 microm. Performances including the GCD and wall loss were examined by classifying dioctyl sebacate of 100 to 600 nm in size and carbon particles of 0.6 to 10 microm in size. The GCD was measured to be 0.95 microm, and the wall loss was highest at 1.1 microm. To add new cut-off diameters, monodisperse NaCl particles ranging from 15 to 70 nm were classified using the proposed virtual impactor with applying a DC potential of 0.25 to 3.0 kV. In this range of the potential, the new cut-off diameters ranging from 15 to 35 nm was added.

Effects of antenatal care and HIV treatment integration on elements of the PMTCT cascade: Results from the SHAIP cluster-randomized controlled trial in Kenya

PubMed Central

Turan, Janet M.; Onono, Maricianah; Steinfeld, Rachel L.; Shade, Starley B.; Owuor, Kevin; Washington, Sierra; Bukusi, Elizabeth A.; Ackers, Marta L.; Kioko, Jackson; Interis, Evelyn C.; Cohen, Craig R.

2015-01-01

Background Integrating antenatal care (ANC) and HIV care may improve uptake and retention in services along the prevention of mother-to-child transmission (PMTCT) cascade. The current study aimed to determine if integration of HIV services into ANC settings improves PMTCT service utilization outcomes. Methods ANC clinics in rural Kenya were randomized to integrated (6 clinics, 569 women) or non-integrated (6 clinics, 603 women) services. Intervention clinics provided all HIV services, including highly active antiretroviral therapy (HAART), while control clinics provided PMTCT services but referred women to HIV care clinics within the same facility. PMTCT utilization outcomes among HIV-infected women (maternal HIV care enrollment, HAART initiation, and 3-month infant HIV testing uptake) were compared using generalized estimating equations and Cox regression. Results HIV care enrollment was higher in intervention compared to control clinics (69% versus 36%, Odds Ratio (OR)=3.94, 95% Confidence Interval (CI): 1.14–13.63). Median time to enrollment was significantly shorter among intervention arm women (0 versus 8 days, Hazard Ratio (HR)=2.20, 95% CI: 1.62–3.01). Eligible women in the intervention arm were more likely to initiate HAART (40% versus 17%, OR=3.22, 95% CI: 1.81–5.72). Infant testing was more common in the intervention arm (25% versus 18%), however not statistically different. No significant differences were detected in postnatal service uptake or maternal retention. Conclusions Service integration increased maternal HIV care enrollment and HAART uptake. However, PMTCT utilization outcomes were still suboptimal, and postnatal service utilization remained poor in both study arms. Further improvements in the PMTCT cascade will require additional research and interventions. PMID:25967269

Classification of Low Velocity Impactors Using Spiral Sensing of Acousto-Ultrasonic Waves

NASA Astrophysics Data System (ADS)

Agbasi, Chijioke Raphael

The non-linear elastodynamics of a flat plate subjected to low velocity foreign body impacts is studied, resembling the space debris impacts on the space structure. The work is based on a central hypothesis that in addition to identifying the impact locations, the material properties of the foreign objects can also be classified using acousto-ultrasonic signals (AUS). Simultaneous localization of impact point and classification of impact object is quite challenging using existing state-of-the-art structural health monitoring (SHM) approaches. Available techniques seek to report the exact location of impact on the structure, however, the reported information is likely to have errors from nonlinearity and variability in the AUS signals due to materials, geometry, boundary conditions, wave dispersion, environmental conditions, sensor and hardware calibration etc. It is found that the frequency and speed of the guided wave generated in the plate can be quantized based on the impactor's relationship with the plate (i.e. the wave speed and the impactor's mechanical properties are coupled). In this work, in order to characterize the impact location and mechanical properties of imapctors, nonlinear transient phenomenon is empirically studied to decouple the understanding using the dominant frequency band (DFB) and Lag Index (LI) of the acousto-ultrasonic signals. Next the understanding was correlated with the elastic modulus of the impactor to predict transmitted force histories. The proposed method presented in this thesis is especially applicable for SHM where sensors cannot be widely or randomly distributed. Thus a strategic organization and localization of the sensors is achieved by implementing the geometric configuration of Theodorous Spiral Sensor Cluster (TSSC). The performance of TSSC in characterizing the impactor types are compared with other conventional sensor clusters (e.g. square, circular, random etc.) and it is shown that the TSSC is advantageous over conventional localized sensor clusters. It was found that the TSSC provides unbiased sensor voting that boosts sensitivity towards classification of impact events. To prove the concept, a coupled field (multiphysics) finite element model (CFFEM) is developed and a series of experiments were performed. The dominant frequency band (DBF) along with a Lag Index (LI) feature extraction technique was found to be suitable for classifying the impactors. Results show that TSSC with DBF features increase the sensitivity of impactor's elastic modulus, if the covariance of the AUS from the TSSC and other conventional sensor clusters are compared. It is observe that for the impact velocity, geometric and mechanical properties studied herein, longitudinal and flexural waves are excited, and there are quantifiable differences in the Lamb wave signatures excited for different impactor materials. It is found that such differences are distinguishable only by the proposed TSSC, but not by other state-of-the-art sensor configurations used in SHM. This study will be useful for modeling an inverse problem needed for classifying impactor materials and the subsequent reconstruction of force histories via neural network or artificial intelligence. Finally an alternative novel approach is proposed to describe the Probability Map of Impact (PMOI) over the entire structure. PMOI could serve as a read-out tool for simultaneously identifying the impact location and the type of the impactor that has impacted the structure. PMOI is intended to provide high risk areas of the space structures where the incipient damage could exist (e.g. area with PMOI > 95%) after an impact.

DESIGN AND CALIBRATION OF THE EPA PM 2.5 WELL IMPACTOR NINETY-SIX (WINS)

EPA Science Inventory

The EPA well-type impactor ninety-six (WINS) was designed and calibrated to serve as a particle size separation device for the EPA reference method sampler for particulate matter under 2.5 um aerodynamic diameter. The WINS was designed to operate downstream of a PM10 inlet at a...

Preliminary Investigation of Skull Fracture Patterns Using an Impactor Representative of Helmet Back-Face Deformation.

PubMed

Weisenbach, Charles A; Logsdon, Katie; Salzar, Robert S; Chancey, Valeta Carol; Brozoski, Fredrick

2018-03-01

Military combat helmets protect the wearer from a variety of battlefield threats, including projectiles. Helmet back-face deformation (BFD) is the result of the helmet defeating a projectile and deforming inward. Back-face deformation can result in localized blunt impacts to the head. A method was developed to investigate skull injury due to BFD behind-armor blunt trauma. A representative impactor was designed from the BFD profiles of modern combat helmets subjected to ballistic impacts. Three post-mortem human subject head specimens were each impacted using the representative impactor at three anatomical regions (frontal bone, right/left temporo-parietal regions) using a pneumatic projectile launcher. Thirty-six impacts were conducted at energy levels between 5 J and 25 J. Fractures were detected in two specimens. Two of the specimens experienced temporo-parietal fractures while the third specimen experienced no fractures. Biomechanical metrics, including impactor acceleration, were obtained for all tests. The work presented herein describes initial research utilizing a test method enabling the collection of dynamic exposure and biomechanical response data for the skull at the BFD-head interface.

Properties of the dead zone due to the gas cushion effect in PBX 9502

NASA Astrophysics Data System (ADS)

Anderson, William

2017-06-01

The gas cushion effect is a well-known phenomenon in which gas trapped between an impactor and an explosive precompresses and deadens a layer of the explosive. We have conducted a series of impact experiments, with and without a trapped gas layer, on the plastic bonded explosive PBX 9502 (95% TATB and 5% Kel-F 800). In each experiment, a 100-oriented LiF window was glued, with an intervening Al foil (a reflector for VISAR), to the surface of a thin (2.5-3.3 mm) PBX 9502 sample and the opposite surface impacted by an impactor at a velocity sufficient to produce an overdriven detonation. VISAR was used to observe arrival of the resulting shock wave and reverberations between the LiF window and the impactor. In three experiments, a gap of 25-38 mm, filled with He gas at a pressure of 0.79 bar, existed between the impactor and the sample at the beginning of the experiment. In these three experiments, a low-amplitude wave reflected from the interface between the reacted explosive and the dead zone was observed to precede the reflection from the impactor. We have used the observed wave amplitudes and arrival times to quantify the properties of the dead zone and, by comparison to existing EOS data for reacted and unreacted PBX 9502, estimate the extent of reaction in the dead zone. This work was supported by the US Department of Energy under contract DE-AC52-06NA25396.

DESIGN AND CALIBRATION OF THE EPA PM2.5 WELL IMPACTOR NINETY-SIX (WINS)

EPA Science Inventory

The EPA well-type impactor ninety-six (WINS) was designed and calibrated to serve as a particle size separation device for the EPA reference method sampler for particulate matter under 2.5 um aerodynamic diameter. The WINS was designed to operate downstream of a PM10 inlet at a v...

NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR PREPARATION OF PM AND URG IMPACTORS AND IMPACTION PLATES (UA-L-8.1)

EPA Science Inventory

The purpose of this SOP is to describe the stages of preparation required for Harvard particulate matter (PM) sampler impactor: (1) prior to in-field use of the particulate sampling system, (2) in-field sampling, and (3) disassembly after field use. This procedure applies direct...

A Gas-Actuated Projectile Launcher for High-Energy Impact Testing of Structures

NASA Technical Reports Server (NTRS)

Ambur, Damodar R.; Jaunky, Navin; Lawson, Robin E.; Knight, Norman F., Jr.; Lyle, Karen H.

1999-01-01

A gas-act,uated penetration device has been developed for high-energy impact testing of structures. The high-energy impact. t,estiiig is for experimental simulation of uncontained engine failures. The non-linear transient finite element, code LS-DYNA3D has been used in the numerical simula.tions of a titanium rectangular blade with a.n aluminum target, plate. Threshold velocities for different combinations of pitch and yaw angles of the impactor were obtained for the impactor-target, t8est configuration in the numerica.1 simulations. Complet,e penet,ration of the target plate was also simulat,ed numerically. Finally, limited comparison of analytical and experimental results is presented for complete penetration of the target by the impactor.

Measurements of the size dependence of the concentration of nonvolatile material in fog droplets

NASA Astrophysics Data System (ADS)

Ogren, J. A.; Noone, K. J.; Hallberg, A.; Heintzenberg, J.; Schell, D.; Berner, A.; Solly, I.; Kruisz, C.; Reischl, G.; Arends, B. G.; Wobrock, W.

1992-11-01

Measurements of the size dependence of the mass concentration of nonvolatile material dissolved and suspended in fog droplets were obtained with three complementary approaches, covering a size range from c. 1 50µm diameter: a counterflow virtual impactor, an eight-stage aerosol impactor, and a two-stage fogwater impactor. Concentrations were observed to decrease with size over the entire range, contrary to expectations of increasing concentrations at larger sizes. It is possible that the larger droplets had solute concentrations that increased with increasing size, but that the increase was too weak for the measurements to resolve. Future studies should consider the hypothesis that the droplets were coated with a surface-active substance that hindered their uptake of water.

The Small Carry-on Impactor (SCI) and the Hayabusa2 Impact Experiment

NASA Astrophysics Data System (ADS)

Saiki, T.; Imamura, H.; Arakawa, M.; Wada, K.; Takagi, Y.; Hayakawa, M.; Shirai, K.; Yano, H.; Okamoto, C.

2017-07-01

Hayabusa2 is a sample return mission of JAXA launched on 3 December 2014. Hayabusa2 is the successor of Hayabusa, which returned samples from the asteroid Itokawa to the Earth. Although the design of Hayabusa2 follows that of Hayabusa, the former is equipped with some new components. The small carry-on impactor (SCI) is one of those components. The SCI is a compact kinetic impactor designed to remove the asteroid surface regolith locally and create an artificial crater. One of the most important scientific objectives of Hayabusa2 is to investigate the chemical and physical properties of the internal materials and structures of the target body, asteroid Ryugu. Hayabusa2 will attempt to observe the resultant crater with some scientific instruments and to get samples from around the crater. High kinetic energy is required to create a meaningful crater, however, the impact system design needs to fit within strict constraints. Complicated functions, such as a guidance and control system, are not permitted. A special type of shaped charge is used for the acceleration of the impactor of the SCI in order to make system simpler. Using this explosion technique makes it possible to accelerate the impactor very quickly and to hit the asteroid without a guidance system. However, the impact operation will be complicated because the explosive is very powerful and it scatters high-speed debris at the detonation. This paper describes an overview of the SCI system, the results of the development testing and an outline of the impact experiment of the Hayabusa2 mission.

U.S.-MEXICO BORDER PROGRAM ARIZONA BORDER STUDY--STANDARD OPERATING PROCEDURE FOR PREPARATION OF PM AND URG IMPACTORS AND IMPACTION PLATES (UA-L-8.1)

EPA Science Inventory

The purpose of this SOP is to describe the stages of preparation required for Harvard particulate matter (PM) sampler impactor: (1) prior to in-field use of the particulate sampling system, (2) in-field sampling, and (3) disassembly after field use. This procedure applies direct...

Collection and Analysis of Aircraft Emitted Particles

NASA Technical Reports Server (NTRS)

Wilson, James Charles

1999-01-01

The University of Denver Aerosol Group proposed to adapt an impactor system for the collection of particles emitted by aircraft. The collection substrates were electron microscope grids which were analyzed by Dr. Pat Sheridan using a transmission electron microscope. The impactor was flown in the SNIFF behind aircraft and engine emissions were sampled. This report details the results of that work.

Preliminary Analysis of Delta-V Requirements for a Lunar CubeSat Impactor with Deployment Altitude Variations

NASA Astrophysics Data System (ADS)

Song, Young-Joo; Ho, Jin; Kim, Bang-Yeop

2015-09-01

Characteristics of delta-V requirements for deploying an impactor from a mother-ship at different orbital altitudes are analyzed in order to prepare for a future lunar CubeSat impactor mission. A mother-ship is assumed to be orbiting the moon with a circular orbit at a 90 deg inclination and having 50, 100, 150, 200 km altitudes. Critical design parameters that are directly related to the success of the impactor mission are also analyzed including deploy directions, CubeSat flight time, impact velocity, and associated impact angles. Based on derived delta-V requirements, required thruster burn time and fuel mass are analyzed by adapting four different miniaturized commercial onboard thrusters currently developed for CubeSat applications. As a result, CubeSat impact trajectories as well as thruster burn characteristics deployed at different orbital altitudes are found to satisfy the mission objectives. It is concluded that thrust burn time should considered as the more critical design parameter than the required fuel mass when deducing the onboard propulsion system requirements. Results provided through this work will be helpful in further detailed system definition and design activities for future lunar missions with a CubeSat-based payload.

Characterizing the Early Impact Bombardment

NASA Technical Reports Server (NTRS)

Bogard, Donald D.

2005-01-01

The early bombardment revealed in the larger impact craters and basins on the moon was a major planetary process that affected all bodies in the inner solar system, including the Earth and Mars. Understanding the nature and timing of this bombardment is a fundamental planetary problem. The surface density of lunar impact craters within a given size range on a given lunar surface is a measure of the age of that surface relative to other lunar surfaces. When crater densities are combined with absolute radiometric ages determined on lunar rocks returned to Earth, the flux of large lunar impactors through time can be estimated. These studies suggest that the flux of impactors producing craters greater than 1 km in diameter has been approximately constant over the past approx. 3 Gyr. However, prior to 3.0 - 3.5 Gyr the impactor flux was much larger and defines an early bombardment period. Unfortunately, no lunar surface feature older than approx. 4 Gyr is accurately dated, and the surface density of craters are saturated in most of the lunar highlands. This means that such data cannot define the impactor flux between lunar formation and approx. 4 Gyr ago.

Analysis of Atmospheric Aerosols Collected in an Urban Area in Upstate NY Using Proton Induced X-ray Emission (PIXE) Spectroscopy

NASA Astrophysics Data System (ADS)

Smith, Jeremy; Ali, Salina; Nadareski, Benjamin; Safiq, Alexandrea; Yoskowitz, Joshua; Labrake, Scott; Vineyard, Michael

2013-10-01

We examined atmospheric aerosol samples collected in Schenectady NY for evidence of pollution. We collected aerosol samples using a nine stage cascade impactor which distributes the particulate matter by aerodynamic size onto 7.5 μm Kapton foils. We then used a 1MV electrostatic Pelletron accelerator to produce a 2.2 MeV proton beam to hit the impacted foils. X-ray intensity versus energy spectra were collected using an Amptek x-ray detector where the x-rays are produced from the proton beam interacting with the sample. This is called PIXE. The elemental composition and concentrations of the elements present in the aerosol samples were determined using a software package called GUPIX. We have found elements ranging from Al to Pb and in particular have found significant amounts of Pb and Br on some of our impacted foils, with a Br/Pb ratio of 0.6 +/- 0.2 which agrees with previous studies. This result suggests the presence of leaded aviation fuel perhaps due to the proximity of the collection site to a small airport with a significant amount of general aviation traffic. Union College.

Particle engineering using sonocrystallization: salbutamol sulphate for pulmonary delivery.

PubMed

Dhumal, Ravindra S; Biradar, Shailesh V; Paradkar, Anant R; York, Peter

2009-02-23

The aim of present work was to produce fine elongated crystals of salbutamol sulphate (SS) by sonocrystallization for pulmonary delivery and compare with micronized and spray dried SS (SDSS) for in vitro aerosolization behavior. Application of ultrasound during anti-solvent crystallization resulted in fine elongated crystals (sonocrystallized SS; SCSS) compared to aggregates of large irregular crystals obtained without sonication. Higher sonication amplitude, time, concentration and lower processing temperatures favored formation of smaller crystals with narrow particle size distribution (PSD). SCSS was separated from dispersion by spray drying in the form of loose aggregates (SD-SCSS). The fine particle fraction (FPF) of formulations with coarse lactose carrier in cascade impactor increased from 16.66% for micronized SS to 31.12% for SDSS (obtained by spray drying aqueous SS solution) and 44.21% for SD-SCSS, due to reduced cohesive/adhesive forces and aerodynamic size by virtue of elongated shape of crystals. SD-SCSS was stable without any change in crystallinity and aerodynamic behavior for 3 months at 40 degrees C/75% RH, but amorphous SDSS showed recrystallization with poor aerosolization performance on storage. Sonocrystallization, a rapid and simple technique is reported for production of SS crystals suitable for inhalation delivery.

Influence of formulation excipients and physical characteristics of inhalation dry powders on their aerosolization performance.

PubMed

Bosquillon, C; Lombry, C; Préat, V; Vanbever, R

2001-02-23

The objective of this study was to determine the effects of formulation excipients and physical characteristics of inhalation particles on their in vitro aerosolization performance, and thereby to maximize their respirable fraction. Dry powders were produced by spray-drying using excipients that are FDA-approved for inhalation as lactose, materials that are endogenous to the lungs as albumin and dipalmitoylphosphatidylcholine (DPPC); and/or protein stabilizers as trehalose or mannitol. Dry powders suitable for deep lung deposition, i.e. with an aerodynamic diameter of individual particles <3 microm, were prepared. They presented 0.04--0.25 g/cm(3) bulk tap densities, 3--5 microm geometric particle sizes, up to 90% emitted doses and 50% respirable fractions in the Andersen cascade impactor using a Spinhaler inhaler device. The incorporation of lactose, albumin and DPPC in the formulation all improved the aerosolization properties, in contrast to trehalose and the mannitol which decreased powder flowability. The relative proportion of the excipients affected aerosol performance as well. The lower the bulk powder tap density, the higher the respirable fraction. Optimization of in vitro aerosolization properties of inhalation dry powders can be achieved by appropriately selecting composition and physical characteristics of the particles.

Aerosolization properties, surface composition and physical state of spray-dried protein powders.

PubMed

Bosquillon, Cynthia; Rouxhet, Paul G; Ahimou, François; Simon, Denis; Culot, Christine; Préat, Véronique; Vanbever, Rita

2004-10-19

Powder aerosols made of albumin, dipalmitoylphosphatidylcholine (DPPC) and a protein stabilizer (lactose, trehalose or mannitol) were prepared by spray-drying and analyzed for aerodynamic behavior, surface composition and physical state. The powders exited a Spinhaler inhaler as particle aggregates, the size of which depending on composition, spray-drying parameters and airflow rate. However, due to low bulk powder tap density (<0.15 g/cm3), the aerodynamic size of a large fraction of aggregates remained respirable (<5 microm). Fine particle fractions ranged between 21% and 41% in an Andersen cascade impactor operated at 28.3 l/min, with mannitol and lactose providing the most cohesive and free-flowing powders, respectively. Particle surface analysis by X-ray photoelectron spectroscopy (XPS) revealed a surface enrichment with DPPC relative to albumin for powders prepared under certain spray-drying conditions. DPPC self-organized in a gel phase in the particle and no sugar or mannitol crystals were detected by X-ray diffraction. Water sorption isotherms showed that albumin protected lactose from moisture-induced crystallization. In conclusion, a proper combination of composition and spray-drying parameters allowed to obtain dry powders with elevated fine particle fractions (FPFs) and a physical environment favorable to protein stability.

Epizootiological characteristics of viable bacteria and fungi in indoor air from porcine, chicken, or bovine husbandry confinement buildings

PubMed Central

Roque, Katharine; Lim, Gyeong-Dong; Jo, Ji-Hoon; Shin, Kyung-Min; Song, Eun-Seob; Gautam, Ravi; Kim, Chang-Yul; Lee, Kyungsuk; Shin, Seungwon; Yoo, Han-Sang; Heo, Yong

2016-01-01

Microorganisms found in bioaerosols from animal confinement buildings not only foster the risk of spreading diseases among livestock buildings, but also pose health hazards to farm workers and nearby residents. This study identified the various microorganisms present in the air of swine, chicken, and cattle farms with different kinds of ventilation conditions in Korea. Microbial air samples were collected onto Petri dishes with bacterial or fungal growth media using a cascade impactor. Endotoxin levels in total dust were determined by the limulus amebocyte lysate kinetic QCL method. Prevalent Gram-positive bacteria were Staphylococcus (S.) lentus, S. chromogenes, Bacillus (B.) cereus, B. licheniformis, and Enterococcus faecalis, while the dominant fungi and Gram-negative bacteria were Candida albicans and Sphingomonas paucimobilis, respectively. Considering no significant relationship between the indoor dust endotoxin levels and the isolation of Gram-negative bacteria from the indoor air, monitoring the indoor airborne endotoxin level was found to be also critical for risk assessment on health for animals or workers. The present study confirms the importance of microbiological monitoring and control on animal husbandry indoor air to ensure animal and worker welfare. PMID:27456779

Mass-size distribution and concentration of metals from personal exposure to arc welding fume in pipeline construction: a case report.

PubMed

Yang, Show-Yi; Lin, Jia-Ming; Young, Li-Hao; Chang, Ching-Wen

2018-04-07

We investigate exposure to welding fume metals in pipeline construction, which are responsible for severe respiratory problems. We analyzed air samples obtained using size-fractioning cascade impactors that were attached to the welders performing shielded metal and gas tungsten arc welding outdoors. Iron, aluminum, zinc, chromium, manganese, copper, nickel, and lead concentrations in the water-soluble (WS) and water-insoluble (WI) portions were determined separately, using inductively coupled plasma mass spectrometry. The mass-size distribution of welding fume matches a log-normal distribution with two modes. The metal concentrations in the welding fume were ranked as follows: Fe > Al > Zn > Cr > Mn > Ni > Cu > Pb. In the WS portion, the capacities of metals dissolving in water are correlated with the metal species but particle sizes. Particularly, Zn, Mn, and Pb exhibit relatively higher capacities than Cu, Cr, Al, Fe, and Ni. Exposure of the gas-exchange region of the lungs to WS metals were in the range of 4.9% to 34.6% of the corresponding metals in air by considering the particle-size selection in lungs, metal composition by particle size, and the capacities of each metal dissolving in water.

Inheritance of magma ocean differentiation during lunar origin by giant impact

NASA Technical Reports Server (NTRS)

Warren, Paul H.

1992-01-01

The giant impact model for the Moon has won widespread support. It seems to satisfactorily explain the high angular momentum of the Earth-Moon system, and the strong depletion of FeNi in the Moon. This model is usually assumed to entail no significant fractionation of nonvolatile lithophile elements relative to a simple binary mixture of impactor silicates plus protoearth silicates. Although the Earth may have been hot enough before the impact to be completely molten, analysis of the likely number and timing of major impacts in the prehistory of the impactor indicates that a fully molten, undifferentiated condition for that relatively small body is unlikely. Given selective sampling by the giant impact, any significant vertical differentiation within the noncore portion of the impactor would have been largely inherited by the Moon.

Asteroidal impacts and the origin of terrestrial and lunar volatiles

NASA Astrophysics Data System (ADS)

Albarede, Francis; Ballhaus, Chris; Blichert-Toft, Janne; Lee, Cin-Ty; Marty, Bernard; Moynier, Frédéric; Yin, Qing-Zhu

2013-01-01

Asteroids impacting the Earth partly volatilize, partly melt (O'Keefe, J.D., Ahrens, T.J. [1977]. Proc. Lunar Sci. Conf. 8, 3357-3374). While metal rapidly segregates out of the melt and sinks into the core, the vaporized material orbits the Earth and eventually rains back onto its surface. The content of the mantle in siderophile elements and their chondritic relative abundances hence is accounted for, not by the impactors themselves, as in the original late-veneer model (Chou, C.L. [1978]. Proc. Lunar Sci. Conf. 9, 219-230; Morgan, J.W. et al. [1981]. Tectonophysics 75, 47-67), but by the vapor resulting from impacts. The impactor's non-siderophile volatiles, notably hydrogen, are added to the mantle and hydrosphere. The addition of late veneer may have lasted for 130 Ma after isolation of the Solar System and probably longer, i.e., well beyond the giant lunar impact. Constraints from the stable isotopes of oxygen and other elements suggest that, contrary to evidence from highly siderophile elements, ˜4% of CI chondrites accreted to the Earth. The amount of water added in this way during the waning stages of accretion, and now dissolved in the deep mantle or used to oxidize Fe in the mantle and the core, may correspond to 10-25 times the mass of the present-day ocean. The Moon is at least 100 times more depleted than the Earth in volatile elements with the exception of some isolated domains, such as the mantle source of 74220 pyroclastic glasses, which appear to contain significantly higher concentrations of water and other volatiles.

Wild Duck Cluster

NASA Technical Reports Server (NTRS)

2005-01-01

On April 7, 2005, the Deep Impact spacecraft's Impactor Target Sensor camera recorded this image of M11, the Wild Duck cluster, a galactic open cluster located 6 thousand light years away. The camera is located on the impactor spacecraft, which will image comet Tempel 1 beginning 22 hours before impact until about 2 seconds before impact. Impact with comet Tempel 1 is planned for July 4, 2005.

Options and uncertainties in planetary defense: Mission planning and vehicle design for flexible response

NASA Astrophysics Data System (ADS)

Barbee, Brent W.; Syal, Megan Bruck; Dearborn, David; Gisler, Galen; Greenaugh, Kevin; Howley, Kirsten M.; Leung, Ron; Lyzhoft, Josh; Miller, Paul L.; Nuth, Joseph A.; Plesko, Catherine; Seery, Bernard D.; Wasem, Joseph; Weaver, Robert P.; Zebenay, Melak

2018-02-01

This paper is part of an integrated study by NASA and the NNSA to quantitatively understand the response timeframe should a threatening Earth-impacting near-Earth object (NEO) be identified. The two realistic responses considered are the use of a spacecraft functioning as either a kinetic impactor or a nuclear explosive carrier to deflect the approaching NEO. The choice depends on the NEO size and mass, the available response time prior to Earth impact, and the various uncertainties. Whenever practical, the kinetic impactor is the preferred approach, but various factors, such as large uncertainties or short available response time, reduce the kinetic impactor's suitability and, ultimately, eliminate its sufficiency. Herein we examine response time and the activities that occur between the time when an NEO is recognized as being a sufficient threat to require a deflection and the time when the deflection impulse is applied to the NEO. To use a kinetic impactor for successful deflection of an NEO, it is essential to minimize the reaction time and maximize the time available for the impulse delivered to the NEO by the kinetic impactor to integrate forward in time to the eventual deflection of the NEO away from Earth impact. To shorten the response time, we develop tools to survey the profile of needed spacecraft launches and the possible mission payloads. We further present a vehicle design capable of either serving as a kinetic impactor, or, if the need arises, serving as a system to transport a nuclear explosive to the NEO. These results are generated by analyzing a specific case study in which the simulated Earth-impacting NEO is modeled very closely after the real NEO known as 101955 Bennu (1999 RQ36). Bennu was selected for our case study in part because it is the best-studied of the known NEOs. It is also the destination of NASA's OSIRIS-REx sample return mission, which is, at the time of this writing, enroute to Bennu following a September 2016 launch.

PMHS impact response in 3 m/s and 8 m/s nearside impacts with abdomen offset.

PubMed

Miller, Carl S; Madura, Nathaniel H; Schneider, Lawrence W; Klinich, Kathleen D; Reed, Matthew P; Rupp, Jonathan D

2013-11-01

Lateral impact tests were performed using seven male post-mortem human subjects (PMHS) to characterize the force-deflection response of contacted body regions, including the lower abdomen. All tests were performed using a dual-sled, side-impact test facility. A segmented impactor was mounted on a sled that was pneumatically accelerated into a second, initially stationary sled on which a subject was seated facing perpendicular to the direction of impact. Positions of impactor segments were adjusted for each subject so that forces applied to different anatomic regions, including thorax, abdomen, greater trochanter, iliac wing, and thigh, could be independently measured on each PMHS. The impactor contact surfaces were located in the same vertical plane, except that the abdomen plate was offset 5.1 cm towards the subject. The masses of the sleds and the force- deflection characteristics of the energy-absorbing interface material between the sleds were set to provide the impactor sled with a velocity profile that matched the average driver door velocity history produced in a series of side NCAP tests. Impactor padding was also selected so that average ATD pelvis and thorax responses from the same series of side NCAP tests were reproduced when the ATD used in these tests was impacted using the average door-velocity history. Each subject was first impacted on one side of the body using an initial impactor speed of 3 m/s. If a post-test CT scan and strain-gage data revealed two or fewer non-displaced rib fractures, then the PMHS was impacted on the contralateral side of the body at a speed of 8 m/s or 10 m/s. The results of tests in the 3 m/s and 8 m/s conditions were used to develop force-deflection response corridors for the abdomen, force history response corridors for the pelvis (iliac wing and greater trochanter), the midthigh, and the thorax. Response corridors for the lateral acceleration of the pelvis were also developed. Future work will compare side impact ATD responses to these response corridors.

Parallel particle impactor - novel size-selective particle sampler for accurate fractioning of inhalable particles

NASA Astrophysics Data System (ADS)

Trakumas, S.; Salter, E.

2009-02-01

Adverse health effects due to exposure to airborne particles are associated with particle deposition within the human respiratory tract. Particle size, shape, chemical composition, and the individual physiological characteristics of each person determine to what depth inhaled particles may penetrate and deposit within the respiratory tract. Various particle inertial classification devices are available to fractionate airborne particles according to their aerodynamic size to approximate particle penetration through the human respiratory tract. Cyclones are most often used to sample thoracic or respirable fractions of inhaled particles. Extensive studies of different cyclonic samplers have shown, however, that the sampling characteristics of cyclones do not follow the entire selected convention accurately. In the search for a more accurate way to assess worker exposure to different fractions of inhaled dust, a novel sampler comprising several inertial impactors arranged in parallel was designed and tested. The new design includes a number of separated impactors arranged in parallel. Prototypes of respirable and thoracic samplers each comprising four impactors arranged in parallel were manufactured and tested. Results indicated that the prototype samplers followed closely the penetration characteristics for which they were designed. The new samplers were found to perform similarly for liquid and solid test particles; penetration characteristics remained unchanged even after prolonged exposure to coal mine dust at high concentration. The new parallel impactor design can be applied to approximate any monotonically decreasing penetration curve at a selected flow rate. Personal-size samplers that operate at a few L/min as well as area samplers that operate at higher flow rates can be made based on the suggested design. Performance of such samplers can be predicted with high accuracy employing well-established impaction theory.

Inheritance of silicate differentiation during lunar origin by giant impact

NASA Technical Reports Server (NTRS)

Warren, Paul H.

1992-01-01

It is pointed out that the implication of the popular giant impact model of lunar origin (e.g., Hartmann and Davis, 1975; Cameron and Ward, 1976; Stevenson, 1987) is that any depth-related silicate differentiation within the impactor (and/or the earth) at the time of the impact must be partly inherited by the preferentially peripheral matter that forms the moon. This paper presents calculations of the magnitude of the net differentiation of the protolunar matter for a variety of elements and scenarios, with different assumptions regarding the geometries of the 'sampled' peripheral zones, the relative proportions of the earth-derived to impactor-derived matter in the final moon, and the degree to which the impactor mantle had crystallized prior to the giant impact. It is shown that these differention effects constrain the overall plausibility of the giant impact hypothesis.

Microbial Exposure Assessment in Sawmill, Livestock Feed Industry, and Metal Working Fluids Handling Industry

PubMed Central

Park, Haedong; Lee, Inseop

2010-01-01

Objectives The objective of this study is to investigate the distribution patterns and exposure concentrations of bioaerosols in industries suspected to have high levels of bioaerosol exposure. Methods We selected 11 plants including 3 livestock feed plants (LF industry), 3 metal working fluids handling plants (MWFs industry), and 5 sawmills and measured total airborne bacteria, fungi, endotoxins, as well as dust. Airborne bacteria and fungi were measured with one stage impactor, six stage cascade impactor, and gelatin filters. Endotoxins were measured with polycarbonate filters. Results The geometric means (GM) of the airborne concentrations of bacteria, fungi, and endotoxins were 1,864, 2,252 CFU/m3, and 31.5 EU/m3, respectively at the sawmills, followed by the LF industry (535, 585 CFU/m3, and 22.0 EU/m3) and MWFs industry (258, 331 CFU/m3, and 8.7 EU/m3). These concentrations by industry type were significantly statistically different (p < 0.01). The ratio of indoor to outdoor concentration was 6.2, 1.9, 3.2, and 3.2 for bacteria, fungi, endotoxins, and dust in the LF industry, 5.0, 0.9, 2.3, and 12.5 in the MWFs industry, and 3.7, 4.1, 3.3, and 9.7 in sawmills. The respiratory fractions of bioaerosols were differentiated by bioaerosol types and industry types: the respiratory fraction of bacteria in the LF industry, MWF industry, and sawmills was 59.4%, 72.0%, and 57.7%, respectively, and that of fungi was 77.3%, 89.5%, and 83.7% in the same order. Conclusion We found that bioaerosol concentration was the highest in sawmills, followed by LF industry facilities and MWFs industry facilities. The indoor/outdoor ratio of microorganisms was larger than 1 and respiratory fraction of microorganisms was more than 50% of the total microorganism concentrations which might penetrate respiratory tract easily. All these findings suggest that bioaerosol in the surveyed industries should be controlled to prevent worker respiratory diseases. PMID:22953179

Collision forces for compliant projectiles

NASA Technical Reports Server (NTRS)

Grady, Joseph E.

1990-01-01

Force histories resulting from the impact of compliant projectiles were determined experimentally. A long instrumented rod was used as the target, and the impact force was calculated directly from the measured strain response. Results from a series of tests on several different sized impactors were used to define four dimensionless parameters that determine, for a specified impactor velocity and size, the amplitude, duration, shape, and impulse of the impact force history.

The effect of different coating materials on the prevention of powder bounce in the next generation impactor

PubMed Central

Khalili, Shadi Farshbaf; Ghanbarzadeh, Saeed; Nokhodchi, Ali; Hamishehkar, Hamed

2018-01-01

In the process of quality control of pulmonary drug delivery products, aerosolization efficiency is mainly determined using impactors, e.g. next generation impactor (NGI). However, particle bounce may interfere with the validity and accuracy of results due to the overestimation of the respirable fraction. It is suggested that the coating of impactor's stages may prevent the particle bounce. Therefore, coating materials may influence the results of the aerosolization indexes of pulmonary dosage forms. The aim of this study was to investigate if the aerosolization indices are affected differently by using the different coating materials. In this study, the effects of using different materials including Span® 85, Tween® 80, silicon® oil, glycerin and Brij® 35/glycerin mixture recommended for the coating of NGI stages on the aerosolization indices such as fine particle fraction, fine particle dose, mass median aerodynamic diameter, and geometric standard deviation of salbutamol emitted from a commercial metered dose inhaler (MDI), were assessed. Three statistically different results were obtained on using Tween® 80, Span® 85 and silicon oil, and glycerin and Brij®35/glycerin mixture. It can be concluded that the type of coating material influenced the aerosolization indices of the examined MDI in NGIs. PMID:29853937

The effect of different coating materials on the prevention of powder bounce in the next generation impactor.

PubMed

Khalili, Shadi Farshbaf; Ghanbarzadeh, Saeed; Nokhodchi, Ali; Hamishehkar, Hamed

2018-06-01

In the process of quality control of pulmonary drug delivery products, aerosolization efficiency is mainly determined using impactors, e.g. next generation impactor (NGI). However, particle bounce may interfere with the validity and accuracy of results due to the overestimation of the respirable fraction. It is suggested that the coating of impactor's stages may prevent the particle bounce. Therefore, coating materials may influence the results of the aerosolization indexes of pulmonary dosage forms. The aim of this study was to investigate if the aerosolization indices are affected differently by using the different coating materials. In this study, the effects of using different materials including Span ® 85, Tween ® 80, silicon ® oil, glycerin and Brij ® 35/glycerin mixture recommended for the coating of NGI stages on the aerosolization indices such as fine particle fraction, fine particle dose, mass median aerodynamic diameter, and geometric standard deviation of salbutamol emitted from a commercial metered dose inhaler (MDI), were assessed. Three statistically different results were obtained on using Tween ® 80, Span ® 85 and silicon oil, and glycerin and Brij ® 35/glycerin mixture. It can be concluded that the type of coating material influenced the aerosolization indices of the examined MDI in NGIs.

Trust and Reputation Management for Critical Infrastructure Protection

NASA Astrophysics Data System (ADS)

Caldeira, Filipe; Monteiro, Edmundo; Simões, Paulo

Today's Critical Infrastructures (CI) depend of Information and Communication Technologies (ICT) to deliver their services with the required level of quality and availability. ICT security plays a major role in CI protection and risk prevention for single and also for interconnected CIs were cascading effects might occur because of the interdependencies that exist among different CIs. This paper addresses the problem of ICT security in interconnected CIs. Trust and reputation management using the Policy Based Management paradigm is the proposed solution to be applied at the CI interconnection points for information exchange. The proposed solution is being applied to the Security Mediation Gateway being developed in the European FP7 MICIE project, to allow for information exchange among interconnected CIs.

Contaminant Interferences with SIMS Analyses of Microparticle Impactor Residues on LDEF Surfaces

NASA Technical Reports Server (NTRS)

Simon, C. G.; Batchelor, D.; Griffis, D. P.; Hunter, J. L.; Misra, V.; Ricks, D. A.; Wortman, J. J.

1992-01-01

Elemental analyses of impactor residues on high purity surface exposed to the low earth orbit (LEO) environment for 5.8 years on Long Duration Exposure Facility (LDEF) has revealed several probable sources for microparticles at this altitude, including natural micrometeorites and manmade debris ranging from paint pigments to bits of stainless steel. A myriad of contamination interferences were identified and their effects on impactor debris identification mitigated during the course of this study. These interferences included pre-, post-, and in-flight deposited particulate surface contaminants, as well as indigenous heterogeneous material contaminants. Non-flight contaminants traced to human origins, including spittle and skin oils, contributed significant levels of alkali-rich carbonaceous interferences. A ubiquitous layer of in-flight deposited silicaceous contamination varied in thickness with location on LDEF and proximity to active electrical fields. In-flight deposited (low velocity) contaminants included urine droplets and bits of metal film from eroded thermal blankets.

Aeolian abrasion on Venus: Preliminary results from the Venus simulator

NASA Technical Reports Server (NTRS)

Marshall, J. R.; Greeley, Ronald; Tucker, D. W.; Pollack, J. B.

1987-01-01

The role of atmospheric pressure on aeolian abrasion was examined in the Venus Simulator with a constant temperature of 737 K. Both the rock target and the impactor were fine-grained basalt. The impactor was a 3 mm diameter angular particle chosen to represent a size of material that is entrainable by the dense Venusian atmosphere and potentially abrasive by virtue of its mass. It was projected at the target 10 to the 5 power times at a velocity of 0.7 m/s. The impactor showed a weight loss of approximately 1.2 x 10 to the -9 power gm per impact with the attrition occurring only at the edges. Results from scanning electron microscope analysis, profilometry, and weight measurement are summarized. It is concluded that particles can incur abrasion at Venusian temperatures even with low impact velocities expected for Venus.

Direct detection of projectile relics from the end of the lunar basin-forming epoch.

PubMed

Joy, Katherine H; Zolensky, Michael E; Nagashima, Kazuhide; Huss, Gary R; Ross, D Kent; McKay, David S; Kring, David A

2012-06-15

The lunar surface, a key proxy for the early Earth, contains relics of asteroids and comets that have pummeled terrestrial planetary surfaces. Surviving fragments of projectiles in the lunar regolith provide a direct measure of the types and thus the sources of exogenous material delivered to the Earth-Moon system. In ancient [>3.4 billion years ago (Ga)] regolith breccias from the Apollo 16 landing site, we located mineral and lithologic relics of magnesian chondrules from chondritic impactors. These ancient impactor fragments are not nearly as diverse as those found in younger (3.4 Ga to today) regolith breccias and soils from the Moon or that presently fall as meteorites to Earth. This suggests that primitive chondritic asteroids, originating from a similar source region, were common Earth-Moon-crossing impactors during the latter stages of the basin-forming epoch.

Impact Tsunami Calculations: Hydrodynamical Simulations vs. Linear Theory

NASA Technical Reports Server (NTRS)

Korycansky, E.; Asphaug, E.; Ward, S. N.

2003-01-01

Tsunamis generated by the impacts of asteroids and comets into the Earth oceans are widely recognized as a potential catastrophic hazard to the Earth s population. Our general conclusion is that linear theory is a reasonably accurate guide to behavior of tsunamis generated by impactors of moderate size, where the initial transient impact cavity is of moderate depth compared to the ocean depth. This is particularly the case for long wavelength waves that propagate fastest and would reach coastlines first. Such tsunamis would be generated in the open ocean by impactors of 300 meters in diameter, which might be expected to strike the Earth once every few thousand years, on the average. Larger impactors produce cavities deep enough to reach the ocean floor; even here, linear theory is applicable if the starting point is chosen at a later phase in the calculation when the impact crater has slumped back to produce a cavity of moderate depth and slope.

Detailed Modeling of the DART Spacecraft Impact into Didymoon

NASA Astrophysics Data System (ADS)

Weaver, R.; Gisler, G.

2017-12-01

In this presentation we will model the impact of the DART spacecraft into the target Didymoon. Most previous modeling of this impact has used full density aluminum spheres with a mass of 300 kg or more recently 500 kg. Many of the published scaling laws for crater size and diameter as well as ejecta modeling assume this type of impactor. The actual spacecraft for the DART impact is not solid and does not contain a solid dedicated kinetic impactor. The spacecraft is considered the impactor. Since the spacecraft is significantly larger ( 100 x 100 x 200 cm) in size than a full density aluminum sphere (radius 35 cm) the resulting impact dynamics will be quite different. Here we model both types of impact and compare the results of the simulation for crater size, crater depth and ejecta. This allows for a comparison of the momentum enhancement factor, beta. Suggestions for improvement of the spacecraft design will be given.

Asymmetric shock heating and the terrestrial magma ocean origin of the Moon

PubMed Central

KARATO, Shun-ichiro

2014-01-01

One of the difficulties of the current giant impact model for the origin of the Moon is to explain the marked similarity in the isotopic compositions and the substantial differences in the major element chemistry. Physics of shock heating is analyzed to show that the degree of heating is asymmetric between the impactor and the target, if the target (the proto-Earth) had a magma-ocean but the impactor did not. The magma ocean is heated much more than the solid impactor and the vapor-rich jets come mainly from the magma-ocean from which the Moon might have been formed. In this scenario, the similarity and differences in the composition between the Moon and Earth would be explained as a natural consequence of a collision in the later stage of planetary formation. Including the asymmetry in shock heating is the first step toward explaining the chemical composition of the Moon. PMID:24621956

Asymmetric shock heating and the terrestrial magma ocean origin of the Moon.

PubMed

Karato, Shun-ichiro

2014-01-01

One of the difficulties of the current giant impact model for the origin of the Moon is to explain the marked similarity in the isotopic compositions and the substantial differences in the major element chemistry. Physics of shock heating is analyzed to show that the degree of heating is asymmetric between the impactor and the target, if the target (the proto-Earth) had a magma-ocean but the impactor did not. The magma ocean is heated much more than the solid impactor and the vapor-rich jets come mainly from the magma-ocean from which the Moon might have been formed. In this scenario, the similarity and differences in the composition between the Moon and Earth would be explained as a natural consequence of a collision in the later stage of planetary formation. Including the asymmetry in shock heating is the first step toward explaining the chemical composition of the Moon.

Analysis of equivalent parameters of two spinal cord injury devices: the New York University impactor versus the Infinite Horizon impactor.

PubMed

Park, Jin Hoon; Kim, Jeong Hoon; Oh, Sun-Kyu; Baek, Se Rim; Min, Joongkee; Kim, Yong Whan; Kim, Sang Tae; Woo, Chul-Woong; Jeon, Sang Ryong

2016-11-01

The New York University (NYU) impactor and the Infinite Horizon (IH) impactor are used to create spinal cord injury (SCI) models. However, the parameters of these two devices that yield equivalent SCI severity remain unclear. To identify equivalent parameters, rats with SCIs induced by either device set at various parameters were subjected to behavioral and histologic analyses. This is an animal laboratory study. Groups of eight rats acquired SCIs by dropping a 10 g rod from a height of 25 mm or 50 mm by using the NYU device or by delivering a force of 150 kdyn, 175 kdyn, 200 kdyn, or 250 kdyn by using the IH impactor. All injured rats were tested weekly for 8 weeks by using the Basso, Beattie, and Bresnahan (BBB) test and the ladder rung test. On the 10th week, the lesion volume of each group was measured by using a 9.4 Tesla magnetic resonance imaging (MRI), and the spinal cords were subjected to histologic analysis using anterograde biotinylated dextran amine (BDA) tracing and immunofluorescence staining with an anti-protein kinase C-gamma (PKC-γ) antibody. Basso, Beattie, and Bresnahan test scores between the 25 mm and the 200 kdyn groups as well as between the 50 mm and and 250 kdyn groups were very similar. Although it was not statistically significant, the mean scores of the ladder rung test in the 200 kdyn group were higher than the 25 mm group at all assessment time points. There was a significantly different cavity volume only between the 50 mm and the 200 kdyn groups. Midline sagittal images of the spinal cord on the MRI revealed that the 25 mm group predominantly had dorsal injuries, whereas the 200 kdyn group had deeper injuries. Anterograde tracing with BDA showed that in the 200 kdyn group, the dorsal corticospinal tract of the caudal area of the lesion was labeled. Similar labeling was not observed in the 25 mm group. Immunofluorescence staining of PKC-γ also revealed strong staining of the dorsal corticospinal tract in the 200 kdyn group but not in the 25 mm group. The 25 mm injuries generated by the NYU impactor are generally equivalent to the 200 kdyn injuries generated by using the IH impactor. However, differences in the ladder rung test scores, MRI images, BDA traces, and PKC-γ staining demonstrate that the two devices exert qualitatively different impacts on the spinal cord. Copyright © 2016 Elsevier Inc. All rights reserved.

Continual improvement plan

NASA Technical Reports Server (NTRS)

1994-01-01

NASA's approach to continual improvement (CI) is a systems-oriented, agency-wide approach that builds on the past accomplishments of NASA Headquarters and its field installations and helps achieve NASA's vision, mission, and values. The NASA of the future will fully use the principles of continual improvement in every aspect of its operations. This NASA CI plan defines a systematic approach and a model for continual improvement throughout NASA, stressing systems integration and optimization. It demonstrates NASA's constancy of purpose for improvement - a consistent vision of NASA as a worldwide leader in top-quality science, technology, and management practices. The CI plan provides the rationale, structures, methods, and steps, and it defines NASA's short term (1-year) objectives for improvement. The CI plan presents the deployment strategies necessary for cascading the goals and objectives throughout the agency. It also provides guidance on implementing continual improvement with participation from top leadership and all levels of employees.

Aerosol emissions from forest and grassland burnings in the southern amazon basin and central Brazil

NASA Astrophysics Data System (ADS)

Leslie, Alistair C. D.

1981-03-01

Forest and grassland clearing by means of prescribed fires in tropical areas of the world may be responsible for large inputs of fine particulates to the global atmosphere besides being a major source of trace gases. The major continents on which extensive biomass burning takes place are Africa and South America. Such agricultural practices of burning have been employed throughout man's existence, but the importance and significance of such burning relative to anthropogenic industrial emissions to the atmosphere has not until extremely recently been seriously studied. In August-September 1979 project "Brushfire 1979" took place based in Brasília, Brazil. The Air Quality Division of the National Center for Atmospheric Research made ground level and aircraft measurements of trace gases (e.g. CO 2, CO, CH 4, N 2O, H 2, CH 3Cl, COS, NO, NO 2, O 3) and Florida State University sampled ground level aerosol emissions from grass and forest burnings. Aerosols were sampled using plastic 7-stage single orifice cascade impactors and FSU type linear and circular "streakers". Long term sampling was made of regional background for total particulates (<15 μmad) with 2 h resolution using streakers and with impactors for 24 h resolution of 7 particle size fractions (<0.25 to >8 μmad). Short term sampling within grass or forest fires was made using impactors incorporated into portable kits containing 4 miniature 12-18 V dc Brailsford pumps and a disposable dry cell power pack. Sampling times of 5-15 min were found optimal under these conditions. Grass fires were sampled in the savannah area northeast of Brasília and forest fires in the state of Mato Grosso on the southern edge of the dryland forest of the Amazon basin. Residual ash samples were collected. All of the samples were analyzed at Florida State University using PIXE for 15-20 elements including Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Pb and Sr. Computer reduction of the X-ray spectra was made using the "HEXB" program. One of the prominent features found was the large flux of small particles (<2.0 μm) from both fire types. P, S and Cl were mostly small particle, Mg, Al, Si and K showed a bimodal distribution biased towards the small particle range, while Ca, Ti and Fe (crustal elements) predominated in the large particle mode. As Cl was found to be exclusively small particle, a formation mechanism in which HCl gas neutralizes small organic particles containing P and S may be hypothesized. A much more extensive field program for the summer of 1980 is planned to take place in the central Amazon basin using ground and airborne aerosol samplers, to capitalize on the work pioneered in this study.

A volatile topic: Parsing out the details of Earth's formation through experimental metal-silicate partitioning of volatile and moderately volatile elements

NASA Astrophysics Data System (ADS)

Mahan, B. M.; Siebert, J.; Blanchard, I.; Badro, J.; Sossi, P.; Moynier, F.

2017-12-01

Volatile and moderately volatile elements display different volatilities and siderophilities, as well as varying sensitivity to thermodynamic controls (X, P, T, fO2) during metal-silicate differentiation. The experimental determination of the metal-silicate partitioning of these elements permits us to evaluate processes controlling the distribution of these elements in Earth. In this work, we have combined metal-silicate partitioning data and results for S, Sn, Zn and Cu, and input these characterizations into Earth formation models. Model parameters such as source material, timing of volatile delivery, fO2 path, and degree of impactor equilibration were varied to encompass an array of possible formation scenarios. These models were then assessed to discern plausible sets of conditions that can produce current observed element-to-element ratios (e.g. S/Zn) in the Earth's present-day mantle, while also satisfying current estimates on the S content of the core, at no more than 2 wt%. The results of our models indicate two modes of accretion that can maintain chondritic element-to-element ratios for the bulk Earth and can arrive at present-day mantle abundances of these elements. The first mode requires the late addition of Earth's entire inventory of these elements (assuming a CI-chondritic composition) and late-stage accretion that is marked by partial equilibration of large impactors. The second, possibly more intuitive mode, requires that Earth accreted - at least initially - from volatile poor material preferentially depleted in S relative to Sn, Zn, and Cu. From a chemical standpoint, this source material is most similar to type I chondrule rich (and S poor) materials (Hewins and Herzberg, 1996; Mahan et al., 2017; Amsellem et al., 2017), such as the metal-bearing carbonaceous chondrites.

The Impact Response of Composite Materials Involved in Helicopter Vulnerability Assessment: Literature Review - Part 2

DTIC Science & Technology

2006-04-01

Nevertheless, several publications analyse impactor shape effects. For example, a study conducted in paper [ Mitrevski , 2005] considered drop-weight...In: Proc. 11th Int. Conf. on Composite Materials, v. 6, Gold Coast, Australia, 14-18 July, 1997, ACSS, Woodhead Publ Ltd, pp. 148-157. [ Mitrevski ...2005] Mitrevski T., Marshall I.H., Thomson R., Jones R., and Whittingham B., The effect of impactor shape on the impact response of composite

The NEOTωIST mission (Near-Earth Object Transfer of angular momentum spin test)

NASA Astrophysics Data System (ADS)

Drube, Line; Harris, Alan W.; Engel, Kilian; Falke, Albert; Johann, Ulrich; Eggl, Siegfried; Cano, Juan L.; Ávila, Javier Martín; Schwartz, Stephen R.; Michel, Patrick

2016-10-01

We present a concept for a kinetic impactor demonstration mission, which intends to change the spin rate of a previously-visited asteroid, in this case 25143 Itokawa. The mission would determine the efficiency of momentum transfer during an impact, and help mature the technology required for a kinetic impactor mission, both of which are important precursors for a future space mission to deflect an asteroid by collisional means in an emergency situation. Most demonstration mission concepts to date are based on changing an asteroid's heliocentric orbit and require a reconnaissance spacecraft to measure the very small orbital perturbation due to the impact. Our concept is a low-cost alternative, requiring only a single launch. Taking Itokawa as an example, an estimate of the order of magnitude of the change in the spin period, δP, with such a mission results in δP of 4 min (0.5%), which could be detectable by Earth-based observatories. Our preliminary study found that a mission concept in which an impactor produces a change in an asteroid's spin rate could provide valuable information for the assessment of the viability of the kinetic-impactor asteroid deflection concept. Furthermore, the data gained from the mission would be of great benefit for our understanding of the collisional evolution of asteroids and the physics behind crater and ejecta-cloud development.

Compressive residual strength of graphite/epoxy laminates after impact

NASA Technical Reports Server (NTRS)

Guy, Teresa A.; Lagace, Paul A.

1992-01-01

The issue of damage tolerance after impact, in terms of the compressive residual strength, was experimentally examined in graphite/epoxy laminates using Hercules AS4/3501-6 in a (+ or - 45/0)(sub 2S) configuration. Three different impactor masses were used at various velocities and the resultant damage measured via a number of nondestructive and destructive techniques. Specimens were then tested to failure under uniaxial compression. The results clearly show that a minimum compressive residual strength exists which is below the open hole strength for a hole of the same diameter as the impactor. Increases in velocity beyond the point of minimum strength cause a difference in the damage produced and cause a resultant increase in the compressive residual strength which asymptotes to the open hole strength value. Furthermore, the results show that this minimum compressive residual strength value is independent of the impactor mass used and is only dependent upon the damage present in the impacted specimen which is the same for the three impactor mass cases. A full 3-D representation of the damage is obtained through the various techniques. Only this 3-D representation can properly characterize the damage state that causes the resultant residual strength. Assessment of the state-of-the-art in predictive analysis capabilities shows a need to further develop techniques based on the 3-D damage state that exists. In addition, the need for damage 'metrics' is clearly indicated.

Constraints on the pre-impact orbits of Theia, the Borealis impactor and the progenitor of Mercury

NASA Astrophysics Data System (ADS)

Jackson, Alan P.; Gabriel, Travis; Asphaug, Erik

2016-10-01

Many aspects of the current dynamical and compositional configuration of the inner Solar System, such as Mercury's large core mass fraction, the angular momentum of the Earth-Moon system, and the reorientation of Mars, have been achieved through the effects of giant impacts. It is possible to relate the impact conditions, especially the velocity, to the pre-impact orbits. This in turn provides insight into the source regions for the terrestrial planets for comparison with N-body accretion models. For example, in the case of the canonical model for the formation of the Moon, previous studies have investigated regions in which the Mars-size impactor, Theia, could be quasi-stable for millions of years. We can however obtain constraints on the orbit of an impactor immediately prior to collision simply by knowing the impact velocity. We consider the canonical Moon formation model, as well as the models of Cuk & Stewart (2012), Canup (2012) and Reufer et al. (2012), to derive from each model its constraints on the pre-impact orbit of Theia. We also consider Mars, and provide constraints on the pre-impact orbit of the impactor suggested to have formed the Borealis basin, and Mercury, namely the Benz et al. (2007) scenario for the formation of Mercury. We discuss the implication of these pre-impact orbits for the origin of the bodies and their compositions.

System-spanning dynamically jammed region in response to impact of cornstarch and water suspensions

NASA Astrophysics Data System (ADS)

Allen, Benjamin; Sokol, Benjamin; Mukhopadhyay, Shomeek; Maharjan, Rijan; Brown, Eric

2018-05-01

We experimentally characterize the structure of concentrated suspensions of cornstarch and water in response to impact. Using surface imaging and particle tracking at the boundary opposite the impactor, we observed that a visible structure and particle flow at the boundary occur with a delay after impact. We show the delay time is about the same time as the strong stress response, confirming that the strong stress response results from deformation of the dynamically jammed structure once it spans between the impactor and a solid boundary. A characterization of this strong stress response is reported in a companion paper [Maharjan, Mukhopadhyay, Allen, Storz, and Brown, Phys. Rev. E 97, 052602 (2018), 10.1103/PhysRevE.97.052602]. We observed particle flow in the outer part of the dynamically jammed region at the bottom boundary, with a net transverse displacement of up to about 5% of the impactor displacement, indicating shear at the boundary. Direct imaging of the surface of the outer part of the dynamically jammed region reveals a change in surface structure that appears the same as the result of dilation in other cornstarch suspensions. Imaging also reveals cracks, like a brittle solid. These observations suggest the dynamically jammed structure can temporarily support stress according to an effective modulus, like a soil or dense granular material, along a network of frictional contacts between the impactor and solid boundary.

Analytical formulation of lunar cratering asymmetries

NASA Astrophysics Data System (ADS)

Wang, Nan; Zhou, Ji-Lin

2016-10-01

Context. The cratering asymmetry of a bombarded satellite is related to both its orbit and impactors. The inner solar system impactor populations, that is, the main-belt asteroids (MBAs) and the near-Earth objects (NEOs), have dominated during the late heavy bombardment (LHB) and ever since, respectively. Aims: We formulate the lunar cratering distribution and verify the cratering asymmetries generated by the MBAs as well as the NEOs. Methods: Based on a planar model that excludes the terrestrial and lunar gravitations on the impactors and assuming the impactor encounter speed with Earth venc is higher than the lunar orbital speed vM, we rigorously integrated the lunar cratering distribution, and derived its approximation to the first order of vM/venc. Numerical simulations of lunar bombardment by the MBAs during the LHB were performed with an Earth-Moon distance aM = 20-60 Earth radii in five cases. Results: The analytical model directly proves the existence of a leading/trailing asymmetry and the absence of near/far asymmetry. The approximate form of the leading/trailing asymmetry is (1 + A1cosβ), which decreases as the apex distance β increases. The numerical simulations show evidence of a pole/equator asymmetry as well as the leading/trailing asymmetry, and the former is empirically described as (1 + A2cos2ϕ), which decreases as the latitude modulus | ϕ | increases. The amplitudes A1,2 are reliable measurements of asymmetries. Our analysis explicitly indicates the quantitative relations between cratering distribution and bombardment conditions (impactor properties and the lunar orbital status) like A1 ∝ vM/venc, resulting in a method for reproducing the bombardment conditions through measuring the asymmetry. Mutual confirmation between analytical model and numerical simulations is found in terms of the cratering distribution and its variation with aM. Estimates of A1 for crater density distributions generated by the MBAs and the NEOs are 0.101-0.159 and 0.117, respectively.

The Lack of Small Craters on Eros is not due to the Yarkovsky Effect

NASA Astrophysics Data System (ADS)

O'Brien, David P.; Greenberg, R.

2007-10-01

Eros approaches saturation for craters larger than 200 m in diameter, but is significantly depleted in smaller craters [1]. It has been suggested that this could reflect a paucity of small impactors in the main belt, due to their removal by the Yarkovsky effect [1,2]. Here we present the results of a self-consistent collisional and dynamical evolution model for the main belt and NEAs, along with a model for the evolution of asteroid crater populations, that show that Eros' lack of small craters is not likely due to the depletion of small impactors by the Yarkovsky effect, or any other depletion mechanism. To produce a main-belt size distribution that is suitably depleted in small impactors to match Eros' small crater population requires a more extreme size-dependent removal rate than the Yarkovsky effect and Poynting-Robertson drag can provide. Using such an extreme removal rate introduces a wave into the model main-belt size distribution that propagates to large sizes, and is inconsistent with the observed main-belt population. Similarly, it introduces a wave in the model NEA population that is inconsistent with the observed NEAs. Eros is not alone in showing a depletion of small craters. Recent observations of the asteroid Itokawa by the Hyabusa spacecraft show relatively few craters, and Yarkovsky depletion of small impactors has again been suggested as a possible explanation [3]. Our work shows that a substantial depletion of small impactors from the main belt would have consequences at large sizes, inconsistent with observations of the actual main-belt and NEA size distributions. Other explanations for the depletion of small craters on asteroid surfaces must be explored [eg. 4,5]. References: [1] Chapman (2002), Icarus 155, p.104. [2] Bell (2001), LPSC XXXII, no.1964. [3] Saito (2006), Science 312, p.1341. [4] Richardson (2004), Science 306, p.1526. [5] Greenberg (2003), DPS 35, no.24.06.

PIXE Analysis of Aerosol and Soil Samples Collected in the Adirondack Mountains

NASA Astrophysics Data System (ADS)

Yoskowitz, Joshua; Ali, Salina; Nadareski, Benjamin; Labrake, Scott; Vineyard, Michael

2014-09-01

We have performed an elemental analysis of aerosol and soil samples collected at Piseco Lake in Upstate New York using proton induced X-ray emission spectroscopy (PIXE). This work is part of a systematic study of airborne pollution in the Adirondack Mountains. Of particular interest is the sulfur content that can contribute to acid rain, a well-documented problem in the Adirondacks. We used a nine-stage cascade impactor to collect the aerosol samples near Piseco Lake and distribute the particulate matter onto Kapton foils by particle size. The soil samples were also collected at Piseco Lake and pressed into cylindrical pellets for experimentation. PIXE analysis of the aerosol and soil samples were performed with 2.2-MeV proton beams from the 1.1-MV Pelletron accelerator in the Union College Ion-Beam Analysis Laboratory. There are higher concentrations of sulfur at smaller particle sizes (0.25-1 μm), suggesting that it could be suspended in the air for days and originate from sources very far away. Other elements with significant concentrations peak at larger particle sizes (1-4 μm) and are found in the soil samples, suggesting that these elements could originate in the soil. The PIXE analysis will be described and the resulting data will be presented.

Emission sources estimation of size-segregated suburban aerosols measured in continental part of Balkan region using PMF5.0 multivariate receptor model

NASA Astrophysics Data System (ADS)

Petrovic, Srdjan; Đuričić-Milanković, Jelena; Anđelković, Ivan; Pantelić, Ana; Gambaro, Andrea; Đorđević, Dragana

2017-04-01

Using Low-Pressure Cascade Impactors by Dr Berner size segregated particulate matter in the size ranges: 0.27 ≤ Dp ≤ 0.53 μm, 0.53 ≤ Dp ≤ 1.06 μm, 1.06 ≤ Dp ≤ 2.09 μm, 2.09 ≤ Dp ≤ 4.11 μm, 4.11 ≤ Dp ≤ 8.11 μm and 8.11 ≤ Dp ≤ 16 μm were collected. Forty-eight-hour size segregated particulate matter samples from atmospheric aerosols in the sub-urban site of Belgrade were measured during two years (in 2012th to 2013in). ICP-MS was used to quantify next elements: Ag, Al, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Hg, Na, Ni, Mg, Mn, Mo, Pb, Se, Sb, Ti, Tl, V and Zn. In order to examine the number of sources and their fingerprints, EPA PMF 5.0 multivariate receptor tool was used. Error estimation methods (bootstrap, displacement, and bootstrap enhanced by displacement) in the analysis of the obtained solutions have enabled proper detection of the number and types of sources. This analysis of the results indicated the existence of four main sources that contribute to air pollution in the suburban area of Belgrade.

Computational fluid dynamics (CFD) assisted performance evaluation of the Twincer™ disposable high-dose dry powder inhaler.

PubMed

de Boer, Anne H; Hagedoorn, Paul; Woolhouse, Robert; Wynn, Ed

2012-09-01

To use computational fluid dynamics (CFD) for evaluating and understanding the performance of the high-dose disposable Twincer™ dry powder inhaler, as well as to learn the effect of design modifications on dose entrainment, powder dispersion and retention behaviour. Comparison of predicted flow and particle behaviour from CFD computations with experimental data obtained with cascade impactor and laser diffraction analysis. Inhaler resistance, flow split, particle trajectories and particle residence times can well be predicted with CFD for a multiple classifier based inhaler like the Twincer™. CFD computations showed that the flow split of the Twincer™ is independent of the pressure drop across the inhaler and that the total flow rate can be decreased without affecting the dispersion efficacy or retention behaviour. They also showed that classifier symmetry can be improved by reducing the resistance of one of the classifier bypass channels, which for the current concept does not contribute to the swirl in the classifier chamber. CFD is a highly valuable tool for development and optimisation of dry powder inhalers. CFD can assist adapting the inhaler design to specific physico-chemical properties of the drug formulation with respect to dispersion and retention behaviour. © 2012 The Authors. JPP © 2012 Royal Pharmaceutical Society.

Fine particulate pollution in the Nanjing northern suburb during summer: composition and sources.

PubMed

An, Junlin; Duan, Qing; Wang, Honglei; Miao, Qing; Shao, Ping; Wang, Jian; Zou, Jianan

2015-09-01

To understand the chemical composition characteristic of pollution in a northern suburb of Nanjing, particle samples were collected by two Andersen cascade impactors from May to July 2013. The positive matrix factorization version 3 (EPA-PMF 3.0) was applied to identify the source contribution of PM2.1 concentrations in the study area. Source categories were determined based on the chemical component abundances in the source profiles. Overall, results indicated that seven factors were obtained. The factors are identified as follows: (I) secondary aerosol, characterized by high concentrations of NH4 (+), NO3 (-), and SO4 (2-), accounting for 20.22 %; (II) metallurgical aerosol, characterized by high concentrations of Pb, Cd, and Zn, accounting for 6.71 %; (III) road dust, characterized by high concentrations of Mg, Ca, Na, Al, and Ba, accounting for 11.85 %; (IV) biomass burning, characterized by high concentrations of K(+), Na(+), Cl(-), and K, accounting for 10.17 %; (V) residual oil, characterized by high concentrations of V and Cr, accounting for 16.63 %; (VI) iron and steel industry, characterized by high concentrations of Mn and Fe, accounting for 9.48 %; and (VII) vehicle exhaust, characterized by high concentrations of organic carbon (OC), Mo, elemental carbon (EC) and K, accounting for 24.94 %.

Co-release of hexabromocyclododecane (HBCD) and Nano- and microparticles from thermal cutting of polystyrene foams.

PubMed

Zhang, Haijun; Kuo, Yu-Ying; Gerecke, Andreas C; Wang, Jing

2012-10-16

Polystyrene foam is a very important insulation material, and hexabromocyclododecane (HBCD) is frequently used as its flame retardant. HBCD is persistent, bioaccumulative, and toxic, and therefore workplace exposure and environmental emission should be avoided. In this study, we investigated the co-release of HBCD and aerosol particles during the thermal cutting of expanded polystyrene foam (EPS) and extruded polystyrene foam (XPS). The generated particles were simultaneously measured by a fast mobility particle sizer (FMPS) and collected by a cascade impactor (NanoMoudi). In the breathing zone of a cutting worker, the number concentration of aerosol particles was above 1 × 10(12) particles m(-3), and the air concentration of HBCD was more than 50 μg m(-3). Most of the released HBCD was partitioned into particles with an aerodynamic diameter at the nanometer scale. The average concentrations of HBCD in these submicrometer particles generated from the thermal cutting of EPS and XPS were 13 times and 15 times higher than the concentrations in raw foams, respectively. An occupational exposure assessment indicated that more than 60% of HBCD and 70% of particles deposited in the lung of cutting worker would be allocated to the alveolar region. The potential subchronic (or chronic) toxicity jointly caused by the particles and HBCD calls for future studies.

Chromate content versus particle size for aircraft paints.

PubMed

LaPuma, Peter T; Rhodes, Brian S

2002-12-01

Many industries rely on the corrosion inhibiting properties of chromate-containing primer paints to protect metal from oxidation. However, chromate contains hexavalent chromium (Cr(6+)), a known human carcinogen. The concentration of Cr(6+) as a function of paint particle size has important implications to worker health and environmental release from paint facilities. This research examines Cr(6+) content as a function of particle size for three types of aircraft primer paints: solvent-based epoxy-polyamide, water-based epoxy-polyamide, and solvent-based polyurethane. Cascade impactors were used to collect and separate paint particles based on their aerodynamic diameter, from 0.7 to 34.1 microm. The mass of the dry paint collected at each stage was determined and an atomic absorption spectrometer was used to analyze for Cr(6+) content. For all three paints, particles less than 7.0 microm contained disproportionately less Cr(6+) per mass of dry paint than larger particles, and the Cr(6+)concentration decreased substantially as particle size decreased. The smallest particles, 0.7 to 1.0 microm, contained approximately 10% of the Cr(6+) content, per mass of dry paint, compared to particles larger than 7.0 microm. The paint gun settings of air to paint ratio was found to have no influence on the Cr(6+) bias.

Assessment of new-generation high-power electronic nicotine delivery system as thermal aerosol generation device for inhaled bronchodilators.

PubMed

Pourchez, Jérémie; de Oliveira, Fabien; Perinel-Ragey, Sophie; Basset, Thierry; Vergnon, Jean-Michel; Prévôt, Nathalie

2017-02-25

A need remains for alternative devices for aerosol drug delivery that are low cost, convenient and easy to use for the patient, but also capable of producing small-sized aerosol particles. This study investigated the potential of recent high power electronic nicotine delivery systems (ENDS) as aerosol generation devices for inhaled bronchodilators. The particle size distribution was measured using a cascade impactor. The delivery of terbutaline sulfate, a current bronchodilator used for asthma or COPD therapy by inhalation, was studied. This drug was quantified by liquid chromatography coupled with tandem mass spectrometry. The particle size distribution in terms of mass frequency (in two ways, gravimetrically and quantitatively through drug assay on each stage) and the terbutaline sulfate concentration in the aerosol were elucidated. The mass median aerodynamic diameter (MMAD) and the drug delivery rose when the power level increased, to reach 5.6±0.4μg/puff with a MMAD of 0.78±0.03μm at 25W. New generation high-power ENDS are very efficient to generate carrier-droplets in the submicron range containing drug molecules with a constant drug concentration whatever the size-fractions. ENDS appear to be highly patient-adaptive. Copyright © 2017 Elsevier B.V. All rights reserved.

Study on Dicarboxylic Acids in Aerosol Samples with Capillary Electrophoresis

PubMed Central

Adler, Heidi; Sirén, Heli

2014-01-01

The research was performed to study the simultaneous detection of a homologous series of α, ω-dicarboxylic acids (C2–C10), oxalic, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic, and sebacic acids, with capillary electrophoresis using indirect UV detection. Good separation efficiency in 2,6-pyridinedicarboxylic acid as background electrolyte modified with myristyl trimethyl ammonium bromide was obtained. The dicarboxylic acids were ionised and separated within five minutes. For the study, authentic samples were collected onto dry cellulose membrane filters of a cascade impactor (12 stages) from outdoor spring aerosols in an urban area. Hot water and ultrasonication extraction methods were used to isolate the acids from membrane filters. Due to the low concentrations of acids in the aerosols, the extracts were concentrated with solid-phase extraction (SPE) before determination. The enrichment of the carboxylic acids was between 86 and 134% with sample pretreatment followed by 100-time increase by preparation of the sample to 50 μL. Inaccuracy was optimised for all the sample processing steps. The aerosols contained dicarboxylic acids C2–C10. Then, mostly they contained C2, C5, and C10. Only one sample contained succinic acid. In the study, the concentrations of the acids in aerosols were lower than 10 ng/m3. PMID:24729915

Particle sizing of pharmaceutical aerosols via direct imaging of particle settling velocities.

PubMed

Fishler, Rami; Verhoeven, Frank; de Kruijf, Wilbur; Sznitman, Josué

2018-02-15

We present a novel method for characterizing in near real-time the aerodynamic particle size distributions from pharmaceutical inhalers. The proposed method is based on direct imaging of airborne particles followed by a particle-by-particle measurement of settling velocities using image analysis and particle tracking algorithms. Due to the simplicity of the principle of operation, this method has the potential of circumventing potential biases of current real-time particle analyzers (e.g. Time of Flight analysis), while offering a cost effective solution. The simple device can also be constructed in laboratory settings from off-the-shelf materials for research purposes. To demonstrate the feasibility and robustness of the measurement technique, we have conducted benchmark experiments whereby aerodynamic particle size distributions are obtained from several commercially-available dry powder inhalers (DPIs). Our measurements yield size distributions (i.e. MMAD and GSD) that are closely in line with those obtained from Time of Flight analysis and cascade impactors suggesting that our imaging-based method may embody an attractive methodology for rapid inhaler testing and characterization. In a final step, we discuss some of the ongoing limitations of the current prototype and conceivable routes for improving the technique. Copyright © 2017 Elsevier B.V. All rights reserved.

Generating monodisperse pharmacological aerosols using the spinning-top aerosol generator.

PubMed

Biddiscombe, Martyn F; Barnes, Peter J; Usmani, Omar S

2006-01-01

Pharmacological aerosols of precisely controlled particle size and narrow dispersity can be generated using the spinning-top aerosol generator (STAG). The ability of the STAG to generate monodisperse aerosols from solutions of raw drug compounds makes it a valuable research instrument. In this paper, the versatility of this instrument has been further demonstrated by aerosolizing a range of commercially available nebulized pulmonary therapy preparations. Nebules of Flixotide (fluticasone propionate), Pulmicort (budesonide), Combivent (salbutamol sulphate and ipratropium bromide), Bricanyl (terbutaline sulphate), Atrovent(ipratropium bromide), and Salamol (salbutamol sulphate) were each mixed with ethanol and delivered to the STAG. Monodisperse drug aerosol distributions were generated with MMADs of 0.95-6.7 microm. To achieve larger particle sizes from the nebulizer drug suspensions, the STAG formed compound particle agglomerates derived from the smaller insoluble drug particles. These compound agglomerates behaved aerodynamically as a single particle, and this was verified using an aerodynamic particle sizer and an Andersen Cascade Impactor. Scanning electron microscope images demonstrated their physical structure. On the other hand using the nebulizer drug solutions, spherical particles proportional to the original droplet diameter were generated. The aerosols generated by the STAG can allow investigators to study the scientific principles of inhaled drug deposition and lung physiology for a range of therapeutic agents.

Capability of air filters to retain airborne bacteria and molds in heating, ventilating and air-conditioning (HVAC) systems.

PubMed

Möritz, M; Peters, H; Nipko, B; Rüden, H

2001-07-01

The capability of air filters (filterclass: F6, F7) to retain airborne outdoor microorganisms was examined in field experiments in two heating, ventilating and air conditioning (HVAC) systems. At the beginning of the 15-month investigation period, the first filter stages of both HVAC systems were equipped with new unused air filters. The number of airborne bacteria and molds before and behind the filters were determined simultaneously in 14 days-intervals using 6-stage Andersen cascade impactors. Under relatively dry (< 80% R. H.) and warm (> 12 degrees C) outdoor air conditions air filters led to a marked reduction of airborne microorganism concentrations (bacteria by approximately 70% and molds by > 80%). However, during long periods of high relative humidity (> 80% R. H.) a proliferation of bacteria on air filters with subsequent release into the filtered air occurred. These microorganisms were mainly smaller than 1.1 microns therefore being part of the respirable fraction. The results showed furthermore that one possibility to avoid microbial proliferation is to limit the relative humidity in the area of the air filters to 80% R. H. (mean of 3 days), e.g. by using preheaters in front of air filters in HVAC-systems.

Mass Median Plume Angle: A novel approach to characterize plume geometry in solution based pMDIs.

PubMed

Moraga-Espinoza, Daniel; Eshaghian, Eli; Smyth, Hugh D C

2018-05-30

High-speed laser imaging (HSLI) is the preferred technique to characterize the geometry of the plume in pressurized metered dose inhalers (pMDIs). However, current methods do not allow for simulation of inhalation airflow and do not use drug mass quantification to determine plume angles. To address these limitations, a Plume Induction Port Evaluator (PIPE) was designed to characterize the plume geometry based on mass deposition patterns. The method is easily adaptable to current pMDI characterization methodologies, uses similar calculations methods, and can be used under airflow. The effect of airflow and formulation on the plume geometry were evaluated using PIPE and HSLI. Deposition patterns in PIPE were highly reproducible and log-normal distributed. Mass Median Plume Angle (MMPA) was a new characterization parameter to describe the effective angle of the droplets deposited in the induction port. Plume angles determined by mass showed a significant decrease in size as ethanol increases which correlates to the decrease on vapor pressure in the formulation. Additionally, airflow significantly decreased the angle of the plumes when cascade impactor was operated under flow. PIPE is an alternative to laser-based characterization methods to evaluate the plume angle of pMDIs based on reliable drug quantification while simulating patient inhalation. Copyright © 2018. Published by Elsevier B.V.

Reduction of airborne radioactive dust by means of a charged water spray.

PubMed

Bigu, J; Grenier, M G

1989-07-01

An electrostatic precipitator based on charged water spray technology has been used in an underground uranium mine to control long-lived radioactive dust and short-lived aerosol concentration in a mine gallery where dust from a rock breaking/ore transportation operation was discharged. Two main sampling stations were established: one upstream of the dust precipitator and one downstream. In addition, dust samplers were placed at different locations between the dust discharge and the end of the mine gallery. Long-lived radioactive dust was measured using cascade impactors and nylon cyclone dust samplers, and measurement of the radioactivity on the samples was carried out by conventional methods. Radon and thoron progeny were estimated using standard techniques. Experiments were conducted under a variety of airflow conditions. A maximum radioactive dust reduction of about 40% (approximately 20% caused by gravitational settling) at a ventilation rate of 0.61 m3/sec was obtained as a result of the combined action of water scrubbing and electrostatic precipitation by the charged water spray electrostatic precipitator. This represents the optimum efficiency attained within the range of ventilation rates investigated. The dust reduction efficiency of the charged water spray decreased with increasing ventilation rate, i.e., decreasing air residence time, and hence, reduced dust cloud/charged water droplets mixing time.

Pollen Characterization in Size Segregated Atmospheric Aerosol

NASA Astrophysics Data System (ADS)

Kolpakova, Anna; Hovorka, Jan; Klán, Miroslav

2017-12-01

The first stage of a High Volumetric Cascade Impactor - HiVol (BGI-900), used for sampling of aerosol particles larger than 10 micrometres in aerodynamic diameter, was tested for bioaerosol sampling. Low air flow-rate and low pressure-drop at the jets of the first stage and high air volume are advantageous parameters, which would favour the use of the first stage for bioaerosol sampling. The sampling went in urban, rural and background localities, Prague, Brezno and Laz respectively in the Czech Republic, in summer and autumn. Pollen was separated from the impaction substrate, polyurethane foam, into homogeneous deposit on Nylon filter. The homogeneity of the deposit varied within 4%. Representative portion of the deposit was analysed by a scanning electron microscopy - SEM. There were taken 485 SEM images from 12 samples in 3 localities. Pollen grains were identified in 295 SEM images and determined into 9 genus and 4 families. Median pollen grain concentrations/deformities were 9m-3/24%, 3m-3/18%, 8m-3/50% for Prague, Brezno and Láz localities respectively. The pollen grains of the Poaceae family were found with the highest frequency in all localities. Number of pollen increased with total aerosol mass in Prague locality only. There were also identified brochosomes, rather unique insect secretion products, in the samples from the Láz locality.

Nicotine delivery from the refill liquid to the aerosol via high-power e-cigarette device.

PubMed

Prévôt, Nathalie; de Oliveira, Fabien; Perinel-Ragey, Sophie; Basset, Thierry; Vergnon, Jean-Michel; Pourchez, Jérémie

2017-06-01

To offer an enhanced and well-controlled nicotine delivery from the refill liquid to the aerosol is a key point to adequately satisfy nicotine cravings using electronic nicotine delivery systems (ENDS). A recent high-power ENDS, exhibiting higher aerosol nicotine delivery than older technologies, was used. The particle size distribution was measured using a cascade impactor. The effects of the refill liquid composition on the nicotine content of each size-fraction in the submicron range were investigated. Nicotine was quantified by liquid chromatography coupled with tandem mass spectrometry. Particle size distribution of the airborne refill liquid and the aerosol nicotine demonstrated that the nicotine is equally distributed in droplets regardless of their size. Results also proved that the nicotine concentration in aerosol was significantly lower compared to un-puffed refill liquid. A part of the nicotine may be left in the ENDS upon depletion, and consequently a portion of the nicotine may not be transferred to the user. Thus, new generation high-power ENDS associated with propylene glycol/vegetable glycerin (PG/VG) based solvent were very efficient to generate carrier-droplets containing nicotine molecules with a constant concentration. Findings highlighted that a portion of the nicotine in the refill liquid may not be transferred to the user.

Giant impactors - Plausible sizes and populations

NASA Technical Reports Server (NTRS)

Hartmann, William K.; Vail, S. M.

1986-01-01

The largest sizes of planetesimals required to explain spin properties of planets are investigated in the context of the impact-trigger hypothesis of lunar origin. Solar system models with different large impactor sources are constructed and stochastic variations in obliquities and rotation periods resulting from each source are studied. The present study finds it highly plausible that earth was struck by a body of about 0.03-0.12 earth masses with enough energy and angular momentum to dislodge mantle material and form the present earth-moon system.

Co-Orbital Debris as a Source of Small Impactors and Albedo Features on Tethys

DTIC Science & Technology

2017-03-01

along the equator in the leading hemisphere of Tethys and correspond to the albedo “lens” identified in both Voyager and Cassini data (see Fig. 1...to determine the small- est fragment that would create a resolvable crater on Tethys, given the current imaging data available. We can confidently...identify craters larger than 1 km in diameter at the best Cassini image resolution of ~215 m/pix. Using the same impactor size to crater diameter

Monitor of the concentration of particles of dense radioactive materials in a stream of air

DOEpatents

Yule, Thomas J.

1979-01-01

A monitor of the concentration of particles of radioactive materials such as plutonium oxide in diameters as small as 1/2 micron includes in combination a first stage comprising a plurality of virtual impactors, a second stage comprising a further plurality of virtual impactors, a collector for concentrating particulate material, a radiation detector disposed near the collector to respond to radiation from collected material and means for moving a stream of air, possibly containing particulate contaminants, through the apparatus.

Trajectory Design for a Single-String Impactor Concept

NASA Technical Reports Server (NTRS)

Dono Perez, Andres; Burton, Roland; Stupl, Jan; Mauro, David

2017-01-01

This paper introduces a trajectory design for a secondary spacecraft concept to augment science return in interplanetary missions. The concept consist of a single-string probe with a kinetic impactor on board that generates an artificial plume to perform in-situ sampling. The trajectory design was applied to a particular case study that samples ejecta particles from the Jovian moon Europa. Results were validated using statistical analysis. Details regarding the navigation, targeting and disposal challenges related to this concept are presented herein.

Impact and cratering rates onto Pluto

NASA Astrophysics Data System (ADS)

Greenstreet, Sarah; Gladman, Brett; McKinnon, William B.

2015-09-01

The New Horizons spacecraft fly-through of the Pluto system in July 2015 will provide humanity's first data for the crater populations on Pluto and its binary companion, Charon. In principle, these surfaces could be dated in an absolute sense, using the observed surface crater density (# craters/km2 larger than some threshold crater diameter D). Success, however, requires an understanding of both the cratering physics and absolute impactor flux. The Canada-France Ecliptic Plane Survey (CFEPS) L7 synthetic model of classical and resonant Kuiper belt populations (Petit, J.M. et al. [2011]. Astron. J. 142, 131-155; Gladman, B. et al. [2012]. Astron. J. 144, 23-47) and the scattering object model of Kaib et al. (Kaib, N., Roškar, R., Quinn, T. [2011]. Icarus 215, 491-507) calibrated by Shankman et al. (Shankman, C. et al. [2013]. Astrophys. J. 764, L2-L5) provide such impact fluxes and thus current primary cratering rates for each dynamical sub-population. We find that four sub-populations (the q < 42AU hot and stirred main classicals, the classical outers, and the plutinos) dominate Pluto's impact flux, each providing ≈ 15- 25 % of the total rate. Due to the uncertainty in how the well-characterized size distribution for Kuiper belt objects (with impactor diameter d > 100km) connects to smaller projectiles, we compute cratering rates using five model impactor size distributions: a single power-law, a power-law with a knee, a power-law with a divot, as well as the "wavy" size distributions described in Minton et al. (Minton, D.A. et al. [2012]. Asteroids Comets Meteors Conf. 1667, 6348) and Schlichting et al. (Schlichting, H.E., Fuentes, C.I., Trilling, D.E. [2013]. Astron. J. 146, 36-42). We find that there is only a small chance that Pluto has been hit in the past 4 Gyr by even one impactor with a diameter larger than the known break in the projectile size distribution (d ≈ 100km) which would create a basin on Pluto (D ⩾ 400km in diameter). We show that due to present uncertainties in the impactor size distribution between d = 1- 100km , computing absolute ages for the surface of Pluto is entirely dependent on the extrapolation to small sizes and thus fraught with uncertainty. We show, however, what the ages would be for several cases and illustrate the relative importance of each Kuiper belt sub-population to the cratering rate, both now and integrated into the past. In addition, we compute the largest "fresh" crater expected to have formed in 1 Gyr on the surface of Pluto and in 3 Gyr on Charon (to 95% confidence) and use the "wavy" size distribution models to predict whether these largest "fresh" craters will provide surfaces for which portions of the crater production function can be measured should most of the target's surface appear saturated. The fly-through results coupled with telescopic surveys that bridge current uncertainties in the d = 10- 100km regime should eventually result in the population estimate uncertainties for the Kuiper belt sub-populations, and thus the impact fluxes onto Pluto and Charon, dipping to < 30 % . We also compute "disruption timescales" (to a factor of three accuracy) for Pluto's smaller satellites: Styx, Nix, Kerberos, and Hydra. We find that none of the four satellites have likely undergone a catastrophic disruption and reassembly event in the past ≈ 4Gyr . In addition, we find that for a knee size distribution with αfaint ⩽ 0.4 (down to sub-km diameters), satellites of all sizes are able to survive catastrophic disruption over the past 4 Gyr.

BILLIARDS: A Demonstration Mission for Hundred-Meter Class Near Earth Asteroid Disruption

NASA Technical Reports Server (NTRS)

Marcus, Matthew; Sloane, Joshua; Ortiz, Oliver; Barbee, Brent W.

2015-01-01

Currently, no planetary defense demonstration mission has ever been flown. While Nuclear Explosive Devices (NEDs) have significantly more energy than a kinetic impactor launched directly from Earth, they present safety and political complications, and therefore may only be used when absolutely necessary. The Baseline Instrumented Lithology Lander, Inspector, and Asteroid Redirection Demonstration System (BILLIARDS) is a demonstration mission for planetary defense, which is capable of delivering comparable energy to the lower range of NED capabilities in the form of a safer kinetic impactor. A small asteroid (<10m) is captured by a spacecraft, which greatly increases the mass available as a kinetic impactor, without the need to bring all of the mass out of Earth's gravity well. The small asteroid is then deflected onto a collision course with a larger (approx. 100m) asteroid. This collision will deflect or disrupt the larger asteroid. To reduce the cost and complexity, an asteroid pair which has a natural close approach is selected.

Cratering Characteristics of the Europa Kinetic Ice Penetrator

NASA Astrophysics Data System (ADS)

Danner, Mariah L.

This thesis further develops the Europa Kinetic Ice Penetrator (EKIP) landing technique for airless bodies, as well as characterizes the effect EKIP would have on Europa's surface. Damage to the extremophile Planococcus Halocryophilus OR1 (PHOR1) during a laboratory hypervelocity impact test was studied the effect of rapid application of pressure to microbes frozen in ice. Significant die-off occurred, however PHOR1 microbes survived a 2.2km/s impact. Field testing the second-stage deployment, as well as to characterize crater morphology of the EKIP system was conducted. With low impact velocities, penetrators consistently had deeper, narrower craters than natural impactors (rocks), and showed less radial and sub-impactor compression. This, and future crater data into harder substrates, will create a cratering hardness curve for this design impactor into airless bodies. This curve, used with the eventual in situ craters, can be used to constrain the hardness and other physical properties of the surface of icy-bodies.

Efficiency of a new bioaerosol sampler in sampling Betula pollen for antigen analyses.

PubMed

Rantio-Lehtimäki, A; Kauppinen, E; Koivikko, A

1987-01-01

A new bioaerosol sampler consisting of Liu-type atmospheric aerosol sampling inlet, coarse particle inertial impactor, two-stage high-efficiency virtual impactor (aerodynamic particle sizes respectively in diameter: greater than or equal to 8 microns, 8-2.5 microns, and 2.5 microns; sampling on filters) and a liquid-cooled condenser was designed, fabricated and field-tested in sampling birch (Betula) pollen grains and smaller particles containing Betula antigens. Both microscopical (pollen counts) and immunochemical (enzyme-linked immunosorbent assay) analyses of each stage were carried out. The new sampler was significantly more efficient than Burkard trap e.g. in sampling particles of Betula pollen size (ca. 25 microns in diameter). This was prominent during pollen peak periods (e.g. May 19th, 1985, in the virtual impactor 9482 and in the Burkard trap 2540 Betula p.g. X m-3 of air). Betula antigens were detected also in filter stages where no intact pollen grains were found; in the condenser unit the antigen concentrations instead were very low.

Impact damage resistance of composite fuselage structure, part 1

NASA Technical Reports Server (NTRS)

Dost, E. F.; Avery, W. B.; Ilcewicz, L. B.; Grande, D. H.; Coxon, B. R.

1992-01-01

The impact damage resistance of laminated composite transport aircraft fuselage structures was studied experimentally. A statistically based designed experiment was used to examine numerous material, laminate, structural, and extrinsic (e.g., impactor type) variables. The relative importance and quantitative measure of the effect of each variable and variable interactions on responses including impactor dynamic response, visibility, and internal damage state were determined. The study utilized 32 three-stiffener panels, each with a unique combination of material type, material forms, and structural geometry. Two manufacturing techniques, tow placement and tape lamination, were used to build panels representative of potential fuselage crown, keel, and lower side-panel designs. Various combinations of impactor variables representing various foreign-object-impact threats to the aircraft were examined. Impacts performed at different structural locations within each panel (e.g., skin midbay, stiffener attaching flange, etc.) were considered separate parallel experiments. The relationship between input variables, measured damage states, and structural response to this damage are presented including recommendations for materials and impact test methods for fuselage structure.

Mass HIV Treatment and Sex Disparities in Life Expectancy: Demographic Surveillance in Rural South Africa

PubMed Central

Bor, Jacob; Rosen, Sydney; Chimbindi, Natsayi; Haber, Noah; Herbst, Kobus; Mutevedzi, Tinofa; Tanser, Frank; Pillay, Deenan; Bärnighausen, Till

2015-01-01

Background Women have better patient outcomes in HIV care and treatment than men in sub-Saharan Africa. We assessed—at the population level—whether and to what extent mass HIV treatment is associated with changes in sex disparities in adult life expectancy, a summary metric of survival capturing mortality across the full cascade of HIV care. We also determined sex-specific trends in HIV mortality and the distribution of HIV-related deaths in men and women prior to and at each stage of the clinical cascade. Methods and Findings Data were collected on all deaths occurring from 2001 to 2011 in a large population-based surveillance cohort (52,964 women and 45,688 men, ages 15 y and older) in rural KwaZulu-Natal, South Africa. Cause of death was ascertained by verbal autopsy (93% response rate). Demographic data were linked at the individual level to clinical records from the public sector HIV treatment and care program that serves the region. Annual rates of HIV-related mortality were assessed for men and women separately, and female-to-male rate ratios were estimated in exponential hazard models. Sex-specific trends in adult life expectancy and HIV-cause-deleted adult life expectancy were calculated. The proportions of HIV deaths that accrued to men and women at different stages in the HIV cascade of care were estimated annually. Following the beginning of HIV treatment scale-up in 2004, HIV mortality declined among both men and women. Female adult life expectancy increased from 51.3 y (95% CI 49.7, 52.8) in 2003 to 64.5 y (95% CI 62.7, 66.4) in 2011, a gain of 13.2 y. Male adult life expectancy increased from 46.9 y (95% CI 45.6, 48.2) in 2003 to 55.9 y (95% CI 54.3, 57.5) in 2011, a gain of 9.0 y. The gap between female and male adult life expectancy doubled, from 4.4 y in 2003 to 8.6 y in 2011, a difference of 4.3 y (95% CI 0.9, 7.6). For women, HIV mortality declined from 1.60 deaths per 100 person-years (95% CI 1.46, 1.75) in 2003 to 0.56 per 100 person-years (95% CI 0.48, 0.65) in 2011. For men, HIV-related mortality declined from 1.71 per 100 person-years (95% CI 1.55, 1.88) to 0.76 per 100 person-years (95% CI 0.67, 0.87) in the same period. The female-to-male rate ratio for HIV mortality declined from 0.93 (95% CI 0.82–1.07) in 2003 to 0.73 (95% CI 0.60–0.89) in 2011, a statistically significant decline (p = 0.046). In 2011, 57% and 41% of HIV-related deaths occurred among men and women, respectively, who had never sought care for HIV in spite of the widespread availability of free HIV treatment. The results presented here come from a poor rural setting in southern Africa with high HIV prevalence and high HIV treatment coverage; broader generalizability is unknown. Additionally, factors other than HIV treatment scale-up may have influenced population mortality trends. Conclusions Mass HIV treatment has been accompanied by faster declines in HIV mortality among women than men and a growing female–male disparity in adult life expectancy at the population level. In 2011, over half of male HIV deaths occurred in men who had never sought clinical HIV care. Interventions to increase HIV testing and linkage to care among men are urgently needed. PMID:26599699

Penetration of multiple thin films in micrometeorite capture cells

NASA Technical Reports Server (NTRS)

Simon, Charles G.

1994-01-01

As part of a continuing effort to develop cosmic dust detectors/collectors for use in space, we performed a series of hypervelocity impact experiments on combined sensor/capture-cell assemblies using 10-200-micron-diameter glass projectiles and olivine crystals at velocities of 0.9-14.4 km/s. The design objective of the space-flight instrument is to measure the trajectories of individual particles with sufficient accuracy to permit identification of their parent bodies and to capture enough impactor material to allow chemical and isotopic analyses of samples returned to Earth. Three different multiple-film small-particle capture cell designs (0.1-100-micron-thick Al foils with approx. 10, 100, and 1800 micron spacing) were evaluated for their ability to capture impactor fragments and residue. Their performances were compared to two other types of capture cells, foil covered Ge crystals, and 0.50 and 0.120 g/cu cm aerogels. All capture cells were tested behind multifilm (1.4-6.0-micron-thick) polyvinylidene fluoride (PVDF) velocity/trajectory sensor devices. Several tests were also done without the PVDF sensors for comparison. The results of this study were reported by Simon in a comprehensive report in which the morphology of impacts and impactor residues in various types of capture cells after passage through two PVDF sensor films is discussed. Impactor fragments in selected capture cells from impacts at velocities up to 6.4 km/s were identified using scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS).

Titanium Isotopes Provide Clues to Lunar Origin

NASA Astrophysics Data System (ADS)

Taylor, G. J.

2012-05-01

The idea that the Moon formed as the result of the giant impact of a Mars-sized impactor with the still-growing Earth explains two central facts about the Earth-Moon system: its total angular momentum (Earth's spin and the Moon's orbital motion), and the sizes of the metallic cores of the Earth (large) and Moon (tiny). This gives cosmochemists some confidence in the hypothesis, but they would greatly appreciate additional compositional tests. One undisputed point is the identical abundance of the three oxygen isotopes in Earth and Moon. Junjun Zhang and colleagues at the University of Chicago (USA) and the University of Bern (Switzerland) have added another isotopic system to the cosmochemical testing tool kit, titanium isotopes. They find that the ratio of titanium-50 to titanium-47 is identical in Earth and Moon to within four parts per million. In contrast, other solar system materials, such as carbonaceous chondrites, vary by considerably more than this-- up to 150 times as much. The identical oxygen and titanium isotopic compositions in Earth and Moon are surprising in light of what we think we know about planet formation and formation of the Moon after a giant impact. The variations in oxygen and titanium isotopes among meteorite types suggest that it is unlikely that the Moon-forming giant impactor would have had the same isotopic composition as the Earth. Simulations show that the Moon ends up constructed mostly (40-75%) from the impactor materials. Thus, the Moon ought to have different isotopic composition than does Earth. The isotopes might have exchanged in the complicated, messy proto-lunar disk (as has been suggested for oxygen isotopes), making them the same. However, Zhang and colleagues suggest that this exchange is unlikely for a refractory element like titanium. Could the impact simulations be greatly overestimating the contributions from the impactor? Was the mixing of building-block materials throughout the inner solar system much less than thought so that the impactor and early Earth actually had the same isotopic compositions? Zhang and coauthors also draw attention to the possibility that the impactor could have been rich in ice, so that the Moon formed mostly from Earth's rocky materials. Questions abound as our understanding of planet formation evolves. Whatever the cause of the titanium-isotope homogeneity in the Earth-Moon system, the new data from titanium isotopes herald new directions for understanding the complicated processes involved in forming the Moon by a giant impact.

Prediction of impact force and duration during low velocity impact on circular composite laminates

NASA Technical Reports Server (NTRS)

Shivakumar, K. N.; Elber, W.; Illg, W.

1983-01-01

Two simple and improved models--energy-balance and spring-mass--were developed to calculate impact force and duration during low velocity impact of circular composite plates. Both models include the contact deformation of the plate and the impactor as well as bending, transverse shear, and membrane deformations of the plate. The plate was transversely isotropic graphite/epoxy composite laminate and the impactor was a steel sphere. Calculated impact forces from the two analyses agreed with each other. The analyses were verified by comparing the results with reported test data.

The impact rate on Earth.

PubMed

Bland, Philip A

2005-12-15

Recent data, and modelling of the interaction between asteroids and the atmosphere, has defined a complete size-frequency distribution for terrestrial impactors, from meteorite-sized objects up to kilometre-sized asteroids, for both the upper atmosphere and the Earth's surface. Although there remain significant uncertainties in the incidence of specific size-fractions of impactors, these estimates allow us to constrain the threat posed by impacts to human populations. It is clear that impacts remain a significant natural hazard, but uniquely, they are a threat that we can accurately predict, and take steps to avoid.

Experimental evidence of impact ignition: 100-fold increase of neutron yield by impactor collision.

PubMed

Azechi, H; Sakaiya, T; Watari, T; Karasik, M; Saito, H; Ohtani, K; Takeda, K; Hosoda, H; Shiraga, H; Nakai, M; Shigemori, K; Fujioka, S; Murakami, M; Nagatomo, H; Johzaki, T; Gardner, J; Colombant, D G; Bates, J W; Velikovich, A L; Aglitskiy, Y; Weaver, J; Obenschain, S; Eliezer, S; Kodama, R; Norimatsu, T; Fujita, H; Mima, K; Kan, H

2009-06-12

We performed integrated experiments on impact ignition, in which a portion of a deuterated polystyrene (CD) shell was accelerated to about 600 km/s and was collided with precompressed CD fuel. The kinetic energy of the impactor was efficiently converted into thermal energy generating a temperature of about 1.6 keV. We achieved a two-order-of-magnitude increase in the neutron yield by optimizing the timing of the impact collision, demonstrating the high potential of impact ignition for fusion energy production.

Genetic algorithms for GNC settings and DACS design application to an asteroid Kinetic Impactor

NASA Astrophysics Data System (ADS)

Vernis, P.; Oliviero, V.

2018-06-01

This paper deals with an application of Genetic Algorithm (GA) tools in order to perform and optimize the settings phase of the Guidance, Navigation, and Control (GNC) data set for the endgame phase of a Kinetic Impactor (KI) targeting a medium-size Near Earth Object (NEO). A coupled optimization of the GNC settings and of the GC-oriented design of the Divert and Attitude Control System (DACS) is also proposed. The illustration of the developed principles is made considering the NEOShield study frame.

Impact-induced solidlike behavior and elasticity in concentrated colloidal suspensions

NASA Astrophysics Data System (ADS)

Chu, Baojin; Salem, David R.

2017-10-01

Modified drop weight impact tests were performed on Si O2 -ethylene glycol concentrated suspensions. Counterintuitive impact-induced solidlike behavior and elasticity, causing significant deceleration and rebound of the impactor, were observed. We provide evidence that the observed large deceleration force on the impactor mainly originates from the hydrodynamic force, and that the elasticity arises from the short-range repulsive force of a solvation layer on the particle surface. This study presents key experimental results to help understand the mechanisms underlying various stress-induced solidification phenomena.

Concussion in professional football: morphology of brain injuries in the NFL concussion model--part 16.

PubMed

Hamberger, Anders; Viano, David C; Säljö, Annette; Bolouri, Hayde

2009-06-01

An animal model of concussions in National Football League players has been described in a previous study. It involves a freely moving 300-g Wistar rat impacted on the side of the head at velocities of 7.4 to 11.2 m/s with a 50-g impactor. The impact causes a 6% to 28% incidence of meningeal hemorrhages and 0.1- to 0.3-mm focal petechiae depending on the impact velocity. This study addresses the immunohistochemical responses of the brain. Twenty-seven tests were conducted with a 50-g impactor and velocities of 7.4, 9.3, or 11.2 m/s. The left temporal region of the helmet-protected head was hit 1 or 3 times. Thirty-one additional tests were conducted with a 100-g impactor. Diffuse axonal injury in distant regions of the brain was assessed with immunohistochemistry for NF-200, the heaviest neurofilament subunit, and glial fibrillary acidic protein, an intermediate filament protein in astrocytes. Hemorrhages were analyzed by unspecific peroxidase. There were 10 controls. A single impact at 7.4 and 9.3 m/s velocity with the 50-g impactor causes minimal neuronal injury and astrocytosis. Repeat impacts with 11.2 m/s velocity and more than 9.3-m/s impacts with 100 g cause diffuse axonal injury and distant injury bilaterally in the cerebral cortex, the subcortical, the white matter, the hippocampus CA1, the corpus callosum, and the striatum, as indicated by NF-200 accumulation in neuronal perikarya 10 days after impact. It also causes reactive astrocytosis in the midline regions of the cerebral cortex and periventricularly. Regions with erythrocyte-loaded blood capillaries indicated brain edema in regions of the cerebral cortex, the brainstem, and the cerebellum. When the immunohistochemical results are extrapolated to professional football players, concussions result in no or minimal brain injury. Repeat impacts at higher velocity or with a heavier mass impactor cause extensive and distant diffuse axonal injury. Based on this model, the threshold for diffuse axonal injury is above even the most severe conditions for National Football League concussion.

Fate of Basin-forming Impact Debris from the Moon

NASA Astrophysics Data System (ADS)

Schultz, P. H.; Bruck Syal, M.; Raskin, C.; Owen, J. M.

2016-12-01

Recent work shows that projectile sizes for basin-forming impacts at the Moon are larger than previously estimated [1]. This finding has implications for the source regions of Late Heavy Bombardment impactors as well as added contributions from debris generated by similar basin-forming collisions. At such large scales, portions of the projectile fragment survive without interactions with the surface and continue downrange along the original trajectory. Such a process most likely occurs for oblique collisions (< 35° from the surface tangent) by bodies larger than 10% of the diameter of the Moon. For the SPA collision, more than 20% of the impacting body survives as newly generated Earth/Moon-crossing objects [2]. Over time some of this debris may have contributed to a spike in impact craters 20-50 km in diameter. Here we model lunar impact basin formation using Spheral, an adaptive Smoothed Particle Hydrodynamics code [3,4], focusing on the dynamical fate of basin ejecta and projectile fragments. Models employ self-gravity for the Moon and impactor and include the Earth's gravitational potential. Large impactors and the Moon are each assigned a two-layer, iron core and forsterite mantle structure. The problem is initialized using hydrostatic equlibrium profiles for pressure and density in both the impactor and target. We begin by modeling debris (target and impactor fragments) ejected from the South Pole-Aitken basin impact and extend the analysis to the Imbrium, Orientale, and Crisium basin formation. [1] Schultz, P.H., Crawford, D.A. Origin and implications of non-radial Imbrium Sculpture on the Moon, Nature 535, 391-394(2016). [2] Schultz, P.H., Crawford, D.A. Origin of nearside structural and geochemical anomalies on the Moon. GSA Special Papers 477, 141-159 (2011). [3] Owen, J. M. ASPH modeling of material damage and failure, in: Proceedings of the Fifth International SPHERIC Workshop, 297-304 (2010). [4] Owen, J. M. A compatibly differenced total energy conserving form of SPH. Int. J. Numer. Meth. Fl. 75, 749-774 (2014). This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52- 07NA27344. LLNL-ABS-699382.

Impact experiments into multiple-mesh targets: Concept development of a lightweight collisional bumper

NASA Technical Reports Server (NTRS)

Hoerz, Friedrich; Cintala, Mark J.; Bernhard, Ronald P.; Cardenas, Frank; Davidson, William; Haynes, Gerald; See, Thomas H.; Winkler, Jerry; Gray, Barry

1993-01-01

The utility of multiple-mesh targets as potential lightweight shields to protect spacecraft in low-Earth orbit against collisional damage is explored. Earlier studies revealed that single meshes comminute hypervelocity impactors with efficiencies comparable to contiguous targets. Multiple interaction of projectile fragments with any number of meshes should lead to increased comminution, deceleration, and dispersion of the projectile, such that all debris exiting the mesh stack possesses low specific energies (ergs/sq cm) that would readily be tolerated by many flight systems. The study is conceptually exploring the sensitivity of major variables such as impact velocity, the specific areal mass (g/sq cm) of the total mesh stack (SM), and the separation distance (S) between individual meshes. Most experiments employed five or ten meshes with total SM typically less than 0.5 the specific mass of the impactor, and silicate glass impactors rather than metal projectiles. While projectile comminution increases with increasing impact velocity due to progressively higher shock stresses, encounters with multiple-meshes at low velocity (1-2 km/s) already lead to significant disruption of the glass impactors, with the resulting fragments being additionally decelerated and dispersed by subsequent meshes, and, unlike most contiguous single-plate bumpers, leading to respectable performance at low velocity. Total specific bumper mass must be the subject of careful trade-off studies; relatively massive bumpers will generate too much debris being dislodged from the bumper itself, while exceptionally lightweight designs will not cause sufficient comminution, deceleration, or dispersion of the impactor. Separation distance was found to be a crucial design parameter, as it controls the dispersion of the fragment cloud. Substantial mass savings could result if maximum separation distances were employed. The total mass of debris dislodged by multiple-mesh stacks is modestly smaller than that of single, contiguous-membrane shields. The cumulative surface area of all penetration holes in multiple mesh stacks is an order of magnitude smaller than that in analog multiple-foil shields, suggesting good long-term performance of the mesh designs. Due to different experimental conditions, direct and quantitative comparison with other lightweight shields is not possible at present.

Osmium isotope and highly siderophile element systematics of lunar impact melt breccias: Implications for the late accretion history of the Moon and Earth

USGS Publications Warehouse

Puchtel, I.S.; Walker, R.J.; James, O.B.; Kring, D.A.

2008-01-01

To characterize the compositions of materials accreted to the Earth-Moon system between about 4.5 and 3.8 Ga, we have determined Os isotopic compositions and some highly siderophile element (HSE: Re, Os, Ir, Ru, Pt, and Pd) abundances in 48 subsamples of six lunar breccias. These are: Apollo 17 poikilitic melt breccias 72395 and 76215; Apollo 17 aphanitic melt breccias 73215 and 73255; Apollo 14 polymict breccia 14321; and lunar meteorite NWA482, a crystallized impact melt. Plots of Ir versus other HSE define excellent linear correlations, indicating that all data sets likely represent dominantly two-component mixtures of a low-HSE target, presumably endogenous component, and a high-HSE, presumably exogenous component. Linear regressions of these trends yield intercepts that are statistically indistinguishable from zero for all HSE, except for Ru and Pd in two samples. The slopes of the linear regressions are insensitive to target rock contributions of Ru and Pd of the magnitude observed; thus, the trendline slopes approximate the elemental ratios present in the impactor components contributed to these rocks. The 187Os/188Os and regression-derived elemental ratios for the Apollo 17 aphanitic melt breccias and the lunar meteorite indicate that the impactor components in these samples have close affinities to chondritic meteorites. The HSE in the Apollo 17 aphanitic melt breccias, however, might partially or entirely reflect the HSE characteristics of HSE-rich granulitic breccia clasts that were incorporated in the impact melt at the time of its creation. In this case, the HSE characteristics of these rocks may reflect those of an impactor that predated the impact event that led to the creation of the melt breccias. The impactor components in the Apollo 17 poikilitic melt breccias and in the Apollo 14 breccia have higher 187Os/188Os, Pt/Ir, and Ru/Ir and lower Os/Ir than most chondrites. These compositions suggest that the impactors they represent were chemically distinct from known chondrite types, and possibly represent a type of primitive material not currently delivered to Earth as meteorites. ?? 2008 Elsevier Ltd.

La masa de los grandes impactores

NASA Astrophysics Data System (ADS)

Parisi, M. G.; Brunini, A.

Los planetas han sido formados fundamentalmente acretando masa a través de colisiones con planetesimales sólidos. La masa más grande de la distribución de planetesimales y las masas máxima y mínima de los impactores, han sido calculadas usando los valores actuales del período y de la inclinación de los planetas (Lissauer & Safronov 1991; Parisi & Brunini 1996). Recientes investigaciones han mostrado, que las órbitas de los planetas gigantes no han sufrido variaciones con el tiempo, siendo su movimiento regular durante su evolución a partir de la finalización de la etapa de acreción (Laskar 1990, 1994). Por lo tanto, la eccentricidad actual de los planetas gigantes se puede utilizar para imponer una cota máxima a las masas y velocidades orbitales de los grandes impactores. Mediante un simple modelo dinámico, y considerando lo arriba mencionado, obtenemos la cota superior para la masa del planetesimal más grande que impactó a cada planeta gigante al final de su etapa de acreción. El resultado más importante de este trabajo es la estimación de la masa máxima permitida para impactar a Júpiter, la cúal es ~ 1.136 × 10 -1, siendo en el caso de Neptuno ~ 3.99 × 10 -2 (expresada en unidades de la masa final de cada planeta). Además, fue posible obtener la velocidad orbital máxima permitida para los impactores como una función de su masa, para cada planeta. Las cotas obtenidas para la masa y velocidad de los impactores de Saturno y Urano (en unidades de la masa y velocidad final de cada planeta respectivamente) son casi las mismas que las obtenidas para Júpiter debido a que estos tres planetas poseen similar eccentricidad actual. Nuestros resultados están en buen acuerdo con los obtenidos por Lissauer & Safronov (1991). Estas cotas podrían ser utilizadas para obtener la distribución de planetesimales en el Sistema Solar primitivo.

Intercomparison and closure calculations using measurements of aerosol species and optical properties during the Yosemite Aerosol Characterization Study

NASA Astrophysics Data System (ADS)

Malm, William C.; Day, Derek E.; Carrico, Christian; Kreidenweis, Sonia M.; Collett, Jeffrey L.; McMeeking, Gavin; Lee, Taehyoung; Carrillo, Jacqueline; Schichtel, Bret

2005-07-01

Physical and optical properties of inorganic aerosols have been extensively studied, but less is known about carbonaceous aerosols, especially as they relate to the non-urban settings such as our nation's national parks and wilderness areas. Therefore an aerosol characterization study was conceived and implemented at one national park that is highly impacted by carbonaceous aerosols, Yosemite. The primary objective of the study was to characterize the physical, chemical, and optical properties of a carbon-dominated aerosol, including the ratio of total organic matter weight to organic carbon, organic mass scattering efficiencies, and the hygroscopic characteristics of a carbon-laden ambient aerosol, while a secondary objective was to evaluate a variety of semi-continuous monitoring systems. Inorganic ions were characterized using 24-hour samples that were collected using the URG and Interagency Monitoring of Protected Visual Environments (IMPROVE) monitoring systems, the micro-orifice uniform deposit impactor (MOUDI) cascade impactor, as well as the semi-continuous particle-into-liquid sampler (PILS) technology. Likewise, carbonaceous material was collected over 24-hour periods using IMPROVE technology along with the thermal optical reflectance (TOR) analysis, while semi-continuous total carbon concentrations were measured using the Rupprecht and Patashnick (R&P) instrument. Dry aerosol number size distributions were measured using a differential mobility analyzer (DMA) and optical particle counter, scattering coefficients at near-ambient conditions were measured with nephelometers fitted with PM10 and PM2.5 inlets, and "dry" PM2.5 scattering was measured after passing ambient air through Perma Pure Nafion® dryers. In general, the 24-hour "bulk" measurements of various aerosol species compared more favorably with each other than with the semi-continuous data. Semi-continuous sulfate measurements correlated well with the 24-hour measurements, but were biased low by about 0.15 μg/m3. Semi-continuous carbon concentrations did not compare favorably with 24-hour measurements. Fine mass closure calculations suggested that the factor for estimating organic mass from measurements of carbon was approximately 1.8. Furthermore, fine scattering closure calculations showed that the use of 4.0 m2/g for the fine organic mass scattering coefficient was an underestimate by at least 30% for periods with high organic mass concentrations.

Indoor Particulate Matter in Houses of Elderly in the Metropolitan Area of Sao Paulo, Brazil

NASA Astrophysics Data System (ADS)

Segalin, B.; Goncalves, F. T.; Fornaro, A.

2015-12-01

Environmental Company of the State of Sao Paulo (CETESB), Brazil, is responsible for particulate matter measurements (PM) in the Metropolitan Area of Sao Paulo (MASP). However, there are few works with indoor measures for MASP. Therefore, the aim of this work is to investigate the PM in households in the MASP. The chosen households were there are aged people over 60 years old. The measurements were sampled during 24 hours using a Personal Cascade Impactor (SKC Cat No. 225-370), which the following aerodynamic diameters: 10.0 - 2.5 (A); 1.0 - 2.5 (B); 0.50 - 1.0 (C); 0.25 - 0.50 (D), and < 0.25 μm (E). Together the impactor, there is a Leland Legacy pump (SKC Cat No. 100-3002) with a flow of 9L/min. It was analyzed 56 households with average values of PM10 and PM2.5 of 30.7 and 23.4 μg/m3, respectively. On average, 76% of PM10 consists of PM2.5, percentage higher than the outdoor environment (60% - CETESB), and 43% of the PM2.5 consists of PM smaller than 0.25 μm. Among all households, there was no exceedance of thresholds national standards PM10 (120 μg/m3) and PM2.5 (60 μg/m3). However, 10.7% of residences exceeded the PM10 threshold of the World Health Organization (50 μg/m3) and 39.2% for PM2.5 (20 μg/m3). The cluster analysis grouped the measures in the houses in four profiles. In three of them were greater amount of mass in ultrafine particles (E), followed by coarse particles (A) with the minimum in C level. The maximum in E may be due to the high contribution vehicular and secondary aerosol outdoor environment. The secondary maximum in A may be due to particles ressuspension and also arising from outdoors. These three groups differ only by the amount of PM measured in the households; they represent high, medium and low PM concentrations. The fourth group has average concentrations, but it presents a different profile because its maximum is in the D rather than E. All data will be analyzed concerning the possible sources.

Experimental research on pedestrian lower leg impact

NASA Astrophysics Data System (ADS)

Constantin, B. A.; Iozsa, D. M.; Stan, C.

2017-10-01

The present paper is centred on the research of deceleration measured at the level of the lower leg during a pedestrian impact in multiple load cases. Basically, the used methodology for physical test setup is similar to EuroNCAP and European Union regulatory requirements. Due cost reduction reasons, it was not used a pneumatic system in order to launch the lower leg impactor in the direction of the vehicle front-end. During the test it was used an opposite solution, namely the vehicle being in motion, aiming the standstill lower leg impactor. The impactor has similar specifications to those at EU level, i.e. dimensions, materials, and principle of measurement of the deceleration magnitude. Therefore, all the results obtained during the study comply with the requirements of both EU regulation and EuroNCAP. As a limitation, due to unavailability of proper sensors in the equipment of the lower leg impactor, that could provide precise results, the bending angle, the shearing and the detailed data at the level of knee ligaments were not evaluated. The knee joint should be improved for future studies as some bending angles observed during the post processing of several impact video files were too high comparing to other studies. The paper highlights the first pedestrian impact physical test conducted by the author, following an extensive research in the field. Deceleration at the level of pedestrian knee can be substantially improved by providing enough volume between the bumper fascia and the front-end structure and by using pedestrian friendly materials for shock absorbers, such as foams.

Mechanical Design and Analysis of a Unilateral Cervical Spinal Cord Contusion Injury Model in Non-Human Primates.

PubMed

Sparrey, Carolyn J; Salegio, Ernesto A; Camisa, William; Tam, Horace; Beattie, Michael S; Bresnahan, Jacqueline C

2016-06-15

Non-human primate (NHP) models of spinal cord injury better reflect human injury and provide a better foundation to evaluate potential treatments and functional outcomes. We combined finite element (FE) and surrogate models with impact data derived from in vivo experiments to define the impact mechanics needed to generate a moderate severity unilateral cervical contusion injury in NHPs (Macaca mulatta). Three independent variables (impactor displacement, alignment, and pre-load) were examined to determine their effects on tissue level stresses and strains. Mechanical measures of peak force, peak displacement, peak energy, and tissue stiffness were analyzed as potential determinants of injury severity. Data generated from FE simulations predicted a lateral shift of the spinal cord at high levels of compression (>64%) during impact. Submillimeter changes in mediolateral impactor position over the midline increased peak impact forces (>50%). Surrogate cords established a 0.5 N pre-load protocol for positioning the impactor tip onto the dural surface to define a consistent dorsoventral baseline position before impact, which corresponded with cerebrospinal fluid displacement and entrapment of the spinal cord against the vertebral canal. Based on our simulations, impactor alignment and pre-load were strong contributors to the variable mechanical and functional outcomes observed in in vivo experiments. Peak displacement of 4 mm after a 0.5N pre-load aligned 0.5-1.0 mm over the midline should result in a moderate severity injury; however, the observed peak force and calculated peak energy and tissue stiffness are required to properly characterize the severity and variability of in vivo NHP contusion injuries.

The effect of the impactor diameter and temperature on low velocity impact behavior of CFRP laminates

NASA Astrophysics Data System (ADS)

Evci, C.; Uyandıran, I.

2017-02-01

Impact damage is one of the major concerns that should be taken into account with the new aircraft and spacecraft structures which employ ever-growing use of composite materials. Considering the thermal loads encountered at different altitudes, both low and high temperatures can affect the properties and impact behavior of composite materials. This study aims to investigate the effect of temperature and impactor diameter on the impact behavior and damage development in balanced and symmetrical CFRP laminates which were manufactured by employing vacuum bagging process with autoclave cure. Instrumented drop-weight impact testing system is used to perform the low velocity impact tests in a range of temperatures ranged from 60 down to -50 °C. Impact tests for each temperature level were conducted using three different hemispherical impactor diameters varying from 10 to 20 mm. Energy profile method is employed to determine the impact threshold energies for damage evolution. The level of impact damage is determined from the dent depth on the impacted face and delamination damage detected using ultrasonic C-Scan technique. Test results reveal that the threshold of penetration energy, main failure force and delamination area increase with impactor diameter at all temperature levels. No clear influence of temperature on the critical force thresholds could be derived. However, penetration threshold energy decreased as the temperature was lowered. Drop in the penetration threshold was more obvious with quite low temperatures. Delamination damage area increased while the temperature decreased from +60 °C to -50 °C.

SPH modelling of energy partitioning during impacts on Venus

NASA Technical Reports Server (NTRS)

Takata, T.; Ahrens, T. J.

1993-01-01

Impact cratering of the Venusian planetary surface by meteorites was investigated numerically using the Smoothed Particle Hydrodynamics (SPH) method. Venus presently has a dense atmosphere. Vigorous transfer of energy between impacting meteorites, the planetary surface, and the atmosphere is expected during impact events. The investigation concentrated on the effects of the atmosphere on energy partitioning and the flow of ejecta and gas. The SPH method is particularly suitable for studying complex motion, especially because of its ability to be extended to three dimensions. In our simulations, particles representing impactors and targets are initially set to a uniform density, and those of atmosphere are set to be in hydrostatic equilibrium. Target, impactor, and atmosphere are represented by 9800, 80, and 4200 particles, respectively. A Tillotson equation of state for granite is assumed for the target and impactor, and an ideal gas with constant specific heat ratio is used for the atmosphere. Two dimensional axisymmetric geometry was assumed and normal impacts of 10km diameter projectiles with velocities of 5, 10, 20, and 40 km/s, both with and without an atmosphere present were modeled.

Rotational and translational considerations in kinetic impact deflection of potentially hazardous asteroids

NASA Astrophysics Data System (ADS)

Zhang, Fei; Xu, Bo; Circi, Christian; Zhang, Lei

2017-04-01

Kinetic impact may be the most reliable and easily implemented method to deflect hazardous asteroids using current technology. Depending on warning time, it can be effective on asteroids with diameters of a few hundred meters. Current impact deflection research often focuses on the orbital dynamics of asteroids. In this paper, we use the ejection outcome of a general oblique impact to calculate how an asteroid's rotational and translational state changes after impact. The results demonstrate how small impactors affect the dynamical state of small asteroids having a diameter of about 100 m. According to these consequences, we propose using several small impactors to hit an asteroid continuously and gently, making the deflection mission relatively flexible. After calculating the rotational variation, we find that the rotational state, especially of slender non-porous asteroids, can be changed significantly. This gives the possibility of using multiple small impactors to mitigate a potentially hazardous asteroid by spinning it up into pieces, or to despin one for future in-situ investigation (e.g., asteroid retrieval or mining).

Quest for impact ignition and its future prospect

NASA Astrophysics Data System (ADS)

Murakami, Masakatsu; Azechi, H.; Watari, T.; Sakaiya, T.; Ohtani, K.; Takeda, K.; Shiraga, H.; Shigemori, K.; Fujioka, S.; Nagatomo, H.; Johzaki, T.; Gardner, J.; Bates, J.; Velikovich, A.; Aglitskiy, Y.; Karasik, M.; Weaver, J.; Obenschain, S.

2009-11-01

Since the impact ignition has been proposed [1], we have achieved such crucial milestones under the operation of Gekko XII (ILE) and NIKE (NRL) laser systems as super-high-velocity acceleration of foils ranging 700-1000 km/s and hundred-fold increase in neutron yield by impact collision [2]. For the latter achievement, the kinetic energy of the impactor was efficiently converted into thermal energy generating a temperature of 1.6 keV. The use of Bromine-doped plastic target are key measure to suppress Rayleigh-Taylor instabilities and thus to achieve effective collisions. Based on these preliminary results, we have done two-dimensional hydrodynamic simulations to demonstrate that ignition occurs when impactor with a velocity beyond 1500 km/s and a density of 50 g/cm3 collides with main fuel with a density of 400 g/cm3, when the maximum impactor kinetic energy is 10 kJ.[4pt] [1] M. Murakami and H. Nagatomo, Nucl. Inst. & Meth. Phys. Res. A544, 67 (2005).[0pt] [2] H. Azechi, et al., Phys. Rev. Lett. 102, 235002 (2009).

Atmosphere Impact Losses

NASA Astrophysics Data System (ADS)

Schlichting, Hilke E.; Mukhopadhyay, Sujoy

2018-02-01

Determining the origin of volatiles on terrestrial planets and quantifying atmospheric loss during planet formation is crucial for understanding the history and evolution of planetary atmospheres. Using geochemical observations of noble gases and major volatiles we determine what the present day inventory of volatiles tells us about the sources, the accretion process and the early differentiation of the Earth. We further quantify the key volatile loss mechanisms and the atmospheric loss history during Earth's formation. Volatiles were accreted throughout the Earth's formation, but Earth's early accretion history was volatile poor. Although nebular Ne and possible H in the deep mantle might be a fingerprint of this early accretion, most of the mantle does not remember this signature implying that volatile loss occurred during accretion. Present day geochemistry of volatiles shows no evidence of hydrodynamic escape as the isotopic compositions of most volatiles are chondritic. This suggests that atmospheric loss generated by impacts played a major role during Earth's formation. While many of the volatiles have chondritic isotopic ratios, their relative abundances are certainly not chondritic again suggesting volatile loss tied to impacts. Geochemical evidence of atmospheric loss comes from the {}3He/{}^{22}Ne, halogen ratios (e.g., F/Cl) and low H/N ratios. In addition, the geochemical ratios indicate that most of the water could have been delivered prior to the Moon forming impact and that the Moon forming impact did not drive off the ocean. Given the importance of impacts in determining the volatile budget of the Earth we examine the contributions to atmospheric loss from both small and large impacts. We find that atmospheric mass loss due to impacts can be characterized into three different regimes: 1) Giant Impacts, that create a strong shock transversing the whole planet and that can lead to atmospheric loss globally. 2) Large enough impactors (m_{cap} ≳ √{2} ρ0 (π h R)^{3/2}, r_{cap}˜25 km for the current Earth), that are able to eject all the atmosphere above the tangent plane of the impact site, where h, R and ρ0 are the atmospheric scale height, radius of the target, and its atmospheric density at the ground. 3) Small impactors (m_{min}>4 πρ0 h3, r_{min}˜ 1 km for the current Earth), that are only able to eject a fraction of the atmospheric mass above the tangent plane. We demonstrate that per unit impactor mass, small impactors with r_{min} < r < r_{cap} are the most efficient impactors in eroding the atmosphere. In fact for the current atmospheric mass of the Earth, they are more than five orders of magnitude more efficient (per unit impactor mass) than giant impacts, implying that atmospheric mass loss must have been common. The enormous atmospheric mass loss efficiency of small impactors is due to the fact that most of their impact energy and momentum is directly available for local mass loss, where as in the giant impact regime a lot of energy and momentum is 'wasted' by having to create a strong shock that can transverse the entirety of the planet such that global atmospheric loss can be achieved. In the absence of any volatile delivery and outgassing, we show that the population of late impactors inferred from the lunar cratering record containing 0.1% M_{\\oplus } is able to erode the entire current Earth's atmosphere implying that an interplay of erosion, outgassing and volatile delivery is likely responsible for determining the atmospheric mass and composition of the early Earth. Combining geochemical observations with impact models suggest an interesting synergy between small and big impacts, where giant impacts create large magma oceans and small and larger impacts drive the atmospheric loss.

Micro-abrasion package capture cell experiment on the trailing edge of LDEF: Impactor chemistry and whipple bumper shield efficiencies

NASA Technical Reports Server (NTRS)

Fitzgerald, Howard J.; Yano, Hajime

1995-01-01

Four of the eight available double layer microparticle capture cells, flown as the experiment A0023 on the trailing (West) face of LDEF, have been extensively studied. An investigation of the chemistry of impactors has been made using SEM/EDX techniques and the effectiveness of the capture cells as bumper shields has also been examined. Studies of these capture cells gave positive EDX results, with 53 percent of impact sites indicating the presence of some chemical residues, the predominant residue identified as being silicon in varying quantities.

Icy Satellites of Saturn: Impact Cratering and Age Determination

NASA Technical Reports Server (NTRS)

Dones, L.; Chapman, C. R.; McKinnon, William B.; Melosh, H. J.; Kirchoff, M. R.; Neukum, G.; Zahnle, K. J.

2009-01-01

Saturn is the first giant planet to be visited by an orbiting spacecraft that can transmit large amounts of data to Earth. Crater counts on satellites from Phoebe inward to the regular satellites and ring moons are providing unprecedented insights into the origin and time histories of the impacting populations. Many Voyager-era scientists concluded that the satellites had been struck by at least two populations of impactors. In this view, the Population I impactors, which were generally judged to be comets orbiting the Sun, formed most of the larger and older craters, while Population II impactors, interpreted as Saturn-orbiting ejecta from impacts on satellites, produced most of the smaller and younger craters. Voyager data also implied that all of the ring moons, and probably some of the midsized classical moons, had been catastrophically disrupted and reaccreted since they formed. We examine models of the primary impactor populations in the Saturn system. At the present time, ecliptic comets, which likely originate in the Kuiper belt/scattered disk, are predicted to dominate impacts on the regular satellites and ring moons, but the models require extrapolations in size (from the observed Kuiper belt objects to the much smaller bodies that produce the craters) or in distance (from the known active Jupiter family comets to 9.5 AU). Phoebe, Iapetus, and perhaps even moons closer to Saturn have been struck by irregular satellites as well. We describe the Nice model, which provides a plausible mechanism by which the entire Solar System might have experienced an era of heavy bombardment long after the planets formed. We then discuss the three cratering chronologies, including one based upon the Nice model, that have been used to infer surface ages from crater densities on the saturnian satellites. After reviewing scaling relations between the properties of impactors and the craters they produce, we provide model estimates of the present-day rate at which comets impact, and catastrophically disrupt, the saturnian moons. Finally, we present crater counts on the satellites from two different groups. Many of the heavily cratered terrains appear to be nearly saturated, so it is difficult to infer the provenance of the impactors from crater counts alone. More large craters have been found on Iapetus than on any other satellite. Enceladus displays an enormous range of surface ages, ranging from the old mid-latitude plains to the extremely young South Polar Terrain. Cassini images provide some evidence for the reality of Population II. Most of the observed craters may have formed in one or more cataclysms, but more work is needed to determine the roles of heliocentric and planetocentric bodies in creating the craters.

Transient isomers in the photodissociation of bromoiodomethane

NASA Astrophysics Data System (ADS)

Marcellini, Moreno; Nasedkin, Alexandr; Zietz, Burkhard; Petersson, Jonas; Vincent, Jonathan; Palazzetti, Federico; Malmerberg, Erik; Kong, Qingyu; Wulff, Michael; van der Spoel, David; Neutze, Richard; Davidsson, Jan

2018-04-01

The photochemistry of halomethanes is fascinating for the complex cascade reactions toward either the parent or newly synthesized molecules. Here, we address the structural rearrangement of photodissociated CH2IBr in methanol and cyclohexane, probed by time-resolved X-ray scattering in liquid solution. Upon selective laser cleavage of the C-I bond, we follow the reaction cascade of the two geminate geometrical isomers, CH2I-Br and CH2Br-I. Both meta-stable isomers decay on different time scales, mediated by solvent interaction, toward the original parent molecule. We observe the internal rearrangement of CH2Br-I to CH2I-Br in cyclohexane by extending the time window up to 3 μs. We track the photoproduct kinetics of CH2Br-I in methanol solution where only one isomer is observed. The effect of the polarity of solvent on the geminate recombination pathways is discussed.

Preparation, In Vitro Characterization, and In Vivo Pharmacokinetic Evaluation of Respirable Porous Microparticles Containing Rifampicin

PubMed Central

Kundawala, Aliasgar; Patel, Vishnu; Patel, Harsha; Choudhary, Dhaglaram

2014-01-01

Abstract This study aimed to prepare and evaluate rifampicin microparticles for the lung delivery of rifampicin as respirable powder. The microparticles were prepared using chitosan by the spray-drying method and evaluated for aerodynamic properties and pulmonary drug absorption. To control the drug release, tripoly-phosphate in different concentrations 0.6, 0.9, 1.2, and 1.5 was employed to get a sustained drug release profile. The microparticles were evaluated for drug loading, % entrapment efficiency, tapped density, morphological characteristics, and in vitro drug release studies. Aerosol properties were determined using the Andersen cascade impactor. Porous microparticles with particle sizes (d0.5) less than 10 μm were obtained. The entrapment of rifampicin in microparticles was up to 72%. In vitro drug release suggested that the crosslinked microparticles showed sustained release for more than 12 hrs. The drug release rate was found to be decreased as the TPP concentration was increased. The microparticles showed a fine particle fraction in the range of 55–63% with mass median aerodynamic diameter (MMAD) values below 3 μm. The in vivo pulmonary absorption of the chitosan microparticles suggested a sustained drug release profile up to 72 hrs with an elimination rate of 0.010 per hr. The studies revealed that the spray-dried porous microparticles have suitable properties to be used as respirable powder in rifampicin delivery to the lungs. PMID:25853075

Mineralogical, chemical and toxicological characterization of urban air particles.

PubMed

Čupr, Pavel; Flegrová, Zuzana; Franců, Juraj; Landlová, Linda; Klánová, Jana

2013-04-01

Systematic characterization of morphological, mineralogical, chemical and toxicological properties of various size fractions of the atmospheric particulate matter was a main focus of this study together with an assessment of the human health risks they pose. Even though near-ground atmospheric aerosols have been a subject of intensive research in recent years, data integrating chemical composition of particles and health risks are still scarce and the particle size aspect has not been properly addressed yet. Filling this gap, however, is necessary for reliable risk assessment. A high volume ambient air sampler equipped with a multi-stage cascade impactor was used for size specific particle collection, and all 6 fractions were a subject of detailed characterization of chemical (PAHs) and mineralogical composition of the particles, their mass size distribution and genotoxic potential of organic extracts. Finally, the risk level for inhalation exposure associated to the carcinogenic character of the studied PAHs has been assessed. The finest fraction (<0.45 μm) exhibited the highest mass, highest active surface, highest amount of associated PAHs and also highest direct and indirect genotoxic potentials in our model air sample. Risk assessment of inhalation scenario indicates the significant cancer risk values in PM 1.5 size fraction. This presented new approach proved to be a useful tool for human health risk assessment in the areas with significant levels of air dust concentration. Copyright © 2013 Elsevier Ltd. All rights reserved.

Inhalation Properties and Stability of Nebulized Naked siRNA Solution for Pulmonary Therapy.

PubMed

Tahara, Kohei; Hashimoto, Wakana; Takeuchi, Hirofumi

2016-01-01

The use of naked unmodified small interfering RNA (N-siRNA) without vector has previously been investigated as a pulmonary therapy. However, little is known regarding stabilities and aerodynamic particle sizes of N-siRNA-containing droplets; nebulizers have not yet been optimized for N-siRNA solutions. Thus, in this study, we investigated the feasibility of inhaled N-siRNA solutions for pulmonary therapy using nebulization. Various nebulizers and N-siRNA concentrations were assessed in terms of siRNA integrity after nebulization, and inhalation properties including aerodynamic particle size were examined. In comparison with ultrasonic-, air-jet-, and vibrating-mesh nebulizers, N-siRNA integrity was not affected by nebulization. Thus, in further experiments, performances of N-siRNA aerosols with different nebulizers and N-siRNA concentrations were evaluated and screened using an aerodynamic particle sizer (APS) which employed the time-of-flight principle or a cascade impactor. Mean mass aerodynamic diameters of N-siRNA-containing droplets from vibrating-mesh nebulizers tended to decrease with increasing N-siRNA concentrations, reflecting the influence of N-siRNA solutions on surface tension, as indicated by contact angles. These data indicate the utility of APS instruments for investigating the nebulized characteristics of expensive drugs including siRNAs and may facilitate the development of N-siRNA inhalation formulations.

Elemental analysis of size-fractionated particulate matter sampled in Göteborg, Sweden

NASA Astrophysics Data System (ADS)

Wagner, Annemarie; Boman, Johan; Gatari, Michael J.

2008-12-01

The aim of the study was to investigate the mass distribution of trace elements in aerosol samples collected in the urban area of Göteborg, Sweden, with special focus on the impact of different air masses and anthropogenic activities. Three measurement campaigns were conducted during December 2006 and January 2007. A PIXE cascade impactor was used to collect particulate matter in 9 size fractions ranging from 16 to 0.06 µm aerodynamic diameter. Polished quartz carriers were chosen as collection substrates for the subsequent direct analysis by TXRF. To investigate the sources of the analyzed air masses, backward trajectories were calculated. Our results showed that diurnal sampling was sufficient to investigate the mass distribution for Br, Ca, Cl, Cu, Fe, K, Sr and Zn, whereas a 5-day sampling period resulted in additional information on mass distribution for Cr and S. Unimodal mass distributions were found in the study area for the elements Ca, Cl, Fe and Zn, whereas the distributions for Br, Cu, Cr, K, Ni and S were bimodal, indicating high temperature processes as source of the submicron particle components. The measurement period including the New Year firework activities showed both an extensive increase in concentrations as well as a shift to the submicron range for K and Sr, elements that are typically found in fireworks. Further research is required to validate the quantification of trace elements directly collected on sample carriers.

Release and Gas-Particle Partitioning Behaviors of Short-Chain Chlorinated Paraffins (SCCPs) During the Thermal Treatment of Polyvinyl Chloride Flooring.

PubMed

Zhan, Faqiang; Zhang, Haijun; Wang, Jing; Xu, Jiazhi; Yuan, Heping; Gao, Yuan; Su, Fan; Chen, Jiping

2017-08-15

Chlorinated paraffin (CP) mixture is a common additive in polyvinyl chloride (PVC) products as a plasticizer and flame retardant. During the PVC plastic life cycle, intentional or incidental thermal processes inevitably cause an abrupt release of short-chain CPs (SCCPs). In this study, the thermal processing of PVC plastics was simulated by heating PVC flooring at 100-200 °C in a chamber. The 1 h thermal treatment caused the release of 1.9-10.7% of the embedded SCCPs. A developed emission model indicated that SCCP release was mainly controlled by material-gas partitioning at 100 °C. However, release control tended to be subjected to material-phase diffusion above 150 °C, especially for SCCP congeners with shorter carbon-chain lengths. A cascade impactor (NanoMoudi) was used to collect particles of different sizes and gas-phase SCCPs. The elevated temperature resulted in a higher partition of SCCPs from the gas-phase to particle-phase. SCCPs were not strongly inclined to form aerosol particles by nucleation, and less present in the Aitken mode particles. Junge-Pankow adsorption model well fitted the partitioning of SCCPs between the gas-phase and accumulation mode particles. Inhalation exposure estimation indicated that PVC processing and recycling workers could face a considerably high risk for exposure to SCCPs.

Size distribution of salbutamol/ipratropium aerosols produced by different nebulizers in the absence and presence of heat and humidification.

PubMed

Yang, Ssu-Han; Yang, Tsung-Ming; Lin, Hui-Ling; Tsai, Ying-Huang; Fang, Tien-Pei; Wan, Gwo-Hwa

2018-02-01

Few studies have evaluated the size distribution of inhaled and exhaled aerosolized drugs, or the effect of heated humidification on particle size and lung deposition. The present study evaluated these aspects of bronchodilator (salbutamol/ipratropium) delivery using a lung model in the absence and presence of heat and humidification. We positioned filters to collect and measure the initial drug, inhaled drug, and exhaled drug. Particle size distribution was evaluated using an 8-stage Marple personal cascade impactor with 0.2-μm polycarbonate filters. A greater inhaled drug mass was delivered using a vibrating mesh nebulizer (VMN) than by using a small volume nebulizer (SVN), when heated humidifiers were not employed. When heated and humidified medical gas was used, there was no significant difference between the inhaled drug mass delivered by the VMN and that delivered by the SVN. A significantly greater mass of inhaled 1.55-μm drug particles was produced by the VMN than with the SVN, under heated and humidified conditions. However, the mass median aerodynamic diameters (MMADs) of the aerosolized drug produced by the SVN and VMN did not differ significantly under the same conditions. The VMN produced more fine particles of salbutamol/ipratropium, and the drug particle size clearly increased in the presence of heat and humidification. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization of a nose-only inhalation exposure system for hydrocarbon mixtures and jet fuels.

PubMed

Martin, Sheppard A; Tremblay, Raphael T; Brunson, Kristyn F; Kendrick, Christine; Fisher, Jeffrey W

2010-04-01

A directed-flow nose-only inhalation exposure system was constructed to support development of physiologically based pharmacokinetic (PBPK) models for complex hydrocarbon mixtures, such as jet fuels. Due to the complex nature of the aerosol and vapor-phase hydrocarbon exposures, care was taken to investigate the chamber hydrocarbon stability, vapor and aerosol droplet compositions, and droplet size distribution. Two-generation systems for aerosolizing fuel and hydrocarbons were compared and characterized for use with either jet fuels or a simple mixture of eight hydrocarbons. Total hydrocarbon concentration was monitored via online gas chromatography (GC). Aerosol/vapor (A/V) ratios, and total and individual hydrocarbon concentrations, were determined using adsorbent tubes analyzed by thermal desorption-gas chromatography-mass spectrometry (TDS-GC-MS). Droplet size distribution was assessed via seven-stage cascade impactor. Droplet mass median aerodynamic diameter (MMAD) was between 1 and 3 mum, depending on the generator and mixture utilized. A/V hydrocarbon concentrations ranged from approximately 200 to 1300 mg/m(3), with between 20% and 80% aerosol content, depending on the mixture. The aerosolized hydrocarbon mixtures remained stable during the 4-h exposure periods, with coefficients of variation (CV) of less than 10% for the total hydrocarbon concentrations. There was greater variability in the measurement of individual hydrocarbons in the A-V phase. In conclusion, modern analytical chemistry instruments allow for improved descriptions of inhalation exposures of rodents to aerosolized fuel.

Determination of size-segregated elements in diesel-biodiesel blend exhaust emissions.

PubMed

Rocha, Luiz Diego Silva; Corrêa, Sergio Machado

2018-04-24

This study was based on the determination of metals in particulate matter emitted by a typical diesel engine used by busses and trucks in Brazil. Emissions were sampled using a cascade impactor, and the engine was operated using diesel with 5% (B5), 10% (B10), 15% (B15), and 20% (B20) of biodiesel. The particulate matter was stratified in different sizes, i.e., 18, 5.6, 3.2, 1.8, 1.0, 0.560, 0.320, 0.180, 0.100, and 0.056 μm. Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, V, and Zn with concentrations within 10 to 1000 ng m -3 were determined. The results indicate a trend in the prevalence of lead, nickel, and chromium in coarse particles and nanoparticles in all blends of fuels. By comparing the results of B5, B10, B15, and B20 fuels, we can confirm that the addition of biodiesel to diesel promotes a reduction of emissions, and by comparing the behavior of the concentration of all elements analyzed, emissions by B10 and B15 fuels are similar, while B5 and B20 suffer significant changes during the process of combustion. Multivariate statistical analysis was used, and it indicates possible sources in three clusters, one for Ni, other for Cr-Mn, and the last one for other metals.

Effects of inhalable microparticle of flower of Lonicera japonica in a mouse model of COPD.

PubMed

Park, Yang-Chun; Jin, Mirim; Kim, Seung-Hyung; Kim, Min-Hee; Namgung, Uk; Yeo, Yoon

2014-01-01

Flower of Lonicera japonica (FLJ) is a traditional herbal medicine widely used in East Asia as an anti-inflammatory and anti-oxidative agent. The purpose of this study is to develop an inhalable powder formulation of FLJ and to evaluate its biological effects in a mouse model of chronic obstructive pulmonary disease (COPD). Inhalable dry powder containing FLJ was produced by spray-drying with leucine as an excipient. Its aerodynamic properties and anti-inflammatory activities were evaluated using the Anderson cascade impactor (ACI) and a mouse model of COPD, respectively. FLJ microparticle (FLJmp) had a hollow spherical shape in electron microscopy and showed aerodynamic properties suitable for inhalation (fine particle fraction of 54.0 ± 4.68% and mass median aerodynamic diameter of 4.6 ± 0.34μm). FLJmp decreased TNF-α and IL-6 expression in RAW264.7 cells activated by lipopolysaccharide (LPS). In mice challenged with LPS and cigarette smoke solution (CSS) to develop COPD, FLJmp decreased the levels of TNF-α and IL-6 in bronchoalveolar fluidas well as the number of inflammatory cells including neutrophils in peripheral blood. In addition, FLJmp induced recovery of elastin and collagen distribution, reduction of caspase-3 expression in lung tissues of COPD mice. Inhalational delivery of FLJ using a microparticle system is a promising strategy for the treatment of COPD. © 2013 Elsevier Ireland Ltd. All rights reserved.

Temporal variability of the chemical composition of surface aerosol in the Moscow region in 1999-2005 from the results of infrared spectroscopy of aerosol samples

NASA Astrophysics Data System (ADS)

Shukurova, L. M.; Gruzdev, A. N.

2010-06-01

The temporal variability of the chemical composition of surface aerosol with particle diameters of 0.7-2 μm is analyzed. This analysis is based on the results of measurements of infrared transmission spectra of aerosol samples collected with the use of a cascade impactor at the Zvenigorod Scientific Station of the Institute of Atmospheric Physics (IAP) in 1999-2005. Seasonal features of the aerosol chemical composition and its dependence on the particle size are revealed. The interdiurnal variability of the aerosol composition depends on the season, and it manifests itself more strongly in winter and spring. Air-mass changes lead to changes in the relation of sulfates and nitrates in the micron fraction of aerosol. The enrichment of samples in nitrates is especially characteristic of the winter and spring seasons. Compounds containing the NO2 group are often met in the samples of aerosol with particle sizes of 0.7-1.3 μm during the cold time of the year. The estimates of the optical thickness of micron aerosol in the sulfate absorption band are obtained, and optical-thickness variations of some scales are detected. The quantitative characteristics of statistical relations between different chemical components of aerosol inside individual fractions and between chemical components of the micron and submicron fractions are obtained and analyzed.

Measuring aerosols generated inside armoured vehicles perforated by depleted uranium ammunition.

PubMed

Parkhurst, M A

2003-01-01

In response to questions raised after the Gulf War about the health significance of exposure to depleted uranium (DU), the US Department of Defense initiated a study designed to provide an improved scientific basis for assessment of possible health effects on soldiers in vehicles struck by these munitions. As part of this study, a series of DU penetrators were fired at an Abrams tank and a Bradley fighting vehicle, and the aerosols generated by vehicle perforation were collected and characterised. A robust sampling system was designed to collect aerosols in this difficult environment and monitor continuously the sampler flow rates. The aerosol samplers selected for these tests included filter cassettes, cascade impactors, a five-stage cyclone and a moving filter. Sampler redundancy was an integral part of the sampling system to offset losses from fragment damage. Wipe surveys and deposition trays collected removable deposited particulate matter. Interior aerosols were analysed for uranium concentration and particle size distribution as a function of time. They were also analysed for uranium oxide phases, particle morphology and dissolution in vitro. These data, currently under independent peer review, will provide input for future prospective and retrospective dose and health risk assessments of inhaled or ingested DU aerosols. This paper briefly discusses the target vehicles, firing trajectories, aerosol samplers and instrumentation control systems, and the types of analyses conducted on the samples.

Comprehensive characterisation of atmospheric aerosols in Budapest, Hungary: physicochemical properties of inorganic species

NASA Astrophysics Data System (ADS)

Salma, Imre; Maenhaut, Willy; Zemplén-Papp, Éva; Záray, Gyula

As part of an air pollution project in Budapest, aerosol samples were collected by stacked filter units and cascade impactors at an urban background site, two downtown sites, and within a road tunnel in field campaigns conducted in 1996, 1998 and 1999. Some criteria pollutants were also measured at one of the downtown sites. The aerosol samples were analysed by one or more of the following methods: instrumental neutron activation analysis, particle-induced X-ray emission analysis, a light reflection technique, gravimetry, thermal profiling carbon analysis and capillary electrophoresis. The quantities measured or derived include atmospheric concentrations of elements (from Na to U), of particulate matter, of black and elemental carbon, and total carbonaceous fraction, of some ionic species (e.g., nitrate and sulphate) in the fine ( <2 μm equivalent aerodynamic diameter, EAD) or in both coarse (10- 2 μm EAD) and fine size fractions, atmospheric concentrations of NO, NO 2, SO 2, CO and total suspended particulate matter, and meteorological parameters. The analytical results were used for characterisation of the concentration levels, elemental composition, time trends, enrichment of and relationships among the aerosol species in coarse and fine size fractions, for studying their fine-to-coarse concentration ratios, spatial and temporal variability, for determining detailed elemental mass size distributions, and for examining the extent of chemical mass closure.

Spray-Freeze Drying: a Suitable Method for Aerosol Delivery of Antibodies in the Presence of Trehalose and Cyclodextrins.

PubMed

Pouya, Maryam Amini; Daneshmand, Behnaz; Aghababaie, Shabnam; Faghihi, Homa; Vatanara, Alireza

2018-05-08

We aimed to prepare spray-freeze-dried powder of IgG considering physicochemical stability and aerodynamic aspects. Spray-freeze drying (SFD) exposes proteins to various stresses which should be compensated by suitable stabilizers. The competence of cyclodextrins (CDs), namely beta-cyclodextrin (βCD) and hydroxypropyl βCD (HPβCD), at very low concentrations, was investigated in the presence of separate mannitol- and trehalose-based formulations. Spray-freeze-dried preparations were quantified in terms of monomer recovery and conformation by size exclusion chromatography (SEC-HPLC) and Fourier transform infrared (FTIR) spectroscopy, respectively. Differential scanning calorimetry (DSC) and X-ray diffractometry (XRD) were employed to identify the thermal characteristics of powders. Particle morphology was visualized by scanning electron microscopy (SEM). Aerodynamic behavior of powders was checked through an Anderson cascade impactor (ACI). Although all formulations protected antibody from aggregation during the SFD process (aggregation < 1%), mannitol-containing ones failed upon the storage (19.54% in the worst case). Trehalose-HPβCD incomparably preserved the formulation with fine particle fraction (FPF) of 51.29%. Crystallization of mannitol resulted in IgG destabilization upon storage. Although employed concentration of CDs is too low (less than 50:1 molar ratio to protein), they successfully served as stabilizing agents in SFD with perfect improvement in aerosol functionality. Graphical Abstract ᅟ.

Inhalable microparticles containing large payload of anti-tuberculosis drugs.

PubMed

Muttil, Pavan; Kaur, Jatinder; Kumar, Kaushlendra; Yadav, Awadh Bihari; Sharma, Rolee; Misra, Amit

2007-10-01

Microparticles containing large payloads of two anti-tuberculosis (TB) drugs were prepared and evaluated for suitability as a dry powder inhalation targeting alveolar macrophages. A solution containing one part each of isoniazid and rifabutin, plus two parts poly(lactic acid) (L-PLA) was spray-dried. Drug content and in vitro release were assayed by HPLC, and DSC was used to elucidate release behaviour. Particle size was measured by laser scattering and aerosol characteristics by cascade impaction using a Lovelace impactor. Microparticles were administered to mice using an in-house inhalation apparatus or by intra-tracheal instillation. Drugs in solution were administered orally and by intra-cardiac injection. Flow cytometry and HPLC were used to investigate the specificity and magnitude of targeting macrophages. Microparticles having drug content approximately 50% (w/w), particle size approximately 5 microm and satisfactory aerosol characteristics (median mass aerodynamic diameter, MMAD=3.57 microm; geometric standard deviation, GSD=1.41 microm; fine particle fraction, FPF(<4.6 microm)=78.91+/-8.4%) were obtained in yields of >60%. About 70% of the payload was released in vitro in 10 days. Microparticles targeted macrophages and not epithelial cells on inhalation. Drug concentrations in macrophages were approximately 20 times higher when microparticles were inhaled rather than drug solutions administered. Microparticles were thus deemed suitable for enhanced targeted drug delivery to lung macrophages.

Mass size distribution and source identification of particulate matter metal components at four urban sites and a background site of Istanbul.

PubMed

Şahin, Ülkü Alver; Polat, Gülfem; Onat, Burcu

2016-06-01

In this study, the size distribution characteristics and metal contents of particulate matter (PM) have been determined. In this scope, PM sampling has been done at five stations in Istanbul. PM filter samples were collected for eight different sizes using the Anderson cascade impactor. PM filters were decomposed and analyzed for 20 metals. The highest median concentration for Fe, Ca, K, and Mg, known as soil metals, were observed as follows: Fe and Ca were observed at Goztepe station (1.20 and 8.28 μg/m(3)), K was observed at Kilyos station (0.33 μg/m(3)), and Mg was observed at Avcilar station (0.37 μg/m(3)). The highest median concentrations for Zn, Cu, Pb, Ni, Cr, V, As, Se, Co, and Cd, known as anthropogenic metals, were observed at Avcilar, Goztepe, and Besiktas stations. Although the lowest metal concentrations was determined at Kilyos stations that was selected as the urban background. The enrichment factors (EFs) of most metals in the fine PM is higher than those in the coarse mode. According to the factor analyses, the most important emission source was observed to be industrial facilities at Avcilar; traffic at Besiktas; traffic and domestic heating at Goztepe; and domestic heating, sea salt aerosols, and ship traffic (in the Bosphorus Channel of Istanbul) at Rasathane.

Self-associated submicron IgG1 particles for pulmonary delivery: effects of non-ionic surfactants on size, shape, stability, and aerosol performance.

PubMed

Srinivasan, Asha R; Shoyele, Sunday A

2013-03-01

The ability to produce submicron particles of monoclonal antibodies of different sizes and shapes would enhance their application to pulmonary delivery. Although non-ionic surfactants are widely used as stabilizers in protein formulations, we hypothesized that non-ionic surfactants will affect the shape and size of submicron IgG particles manufactured through precipitation. Submicron particles of IgG1 were produced by a precipitation process which explores the fact that proteins have minimum solubility but maximum precipitation at the isoelectric point. Non-ionic surfactants were used for size and shape control, and as stabilizing agents. Aerosol performance of the antibody nanoparticles was assessed using Andersen Cascade Impactor. Spinhaler® and Handihaler® were used as model DPI devices. SEM micrographs revealed that the shape of the submicron particles was altered by varying the type of surfactant added to the precipitating medium. Particle size as measured by dynamic light scattering was also varied based on the type and concentration of the surfactant. The surfactants were able to stabilize the IgG during the precipitation process. Polyhedral, sponge-like, and spherical nanoparticles demonstrated improved aerosolization properties compared to irregularly shaped (>20 μm) unprocessed particles. Stable antibody submicron particles of different shapes and sizes were prepared. Careful control of the shape of such particles is critical to ensuring optimized lung delivery by dry powder inhalation.

Orbital and Physical Characteristics of Meter-sized Earth Impactors

NASA Astrophysics Data System (ADS)

Brown, Peter G.; Wiegert, Paul; Clark, David; Tagliaferri, Edward

2015-11-01

We have analysed the orbits and ablation characteristics in the atmosphere of more than 60 earth-impacting meteoroids of one meter in diameter or larger. Using heights at peak luminosity as a proxy for strength, we find that there is roughly an order of magnitude spread in the apparent strength of the population of meter-sized impactors at the Earth. The orbits and physical strength of these objects are consistent with the majority being asteroidal bodies originating from the inner main asteroid belt. We find ~10-15% of our objects have a probable cometary (Jupiter-Family comet and/or Halley-type comet) origin based on orbital characteristics alone. Only half this number, however, show evidence for the expected weaker than average structure compared to asteroidal bodies. Almost all impactors show peak brightness between 20-40 km altitude. Several events have exceptionally high (relative to the remainder of the population) heights of peak brightness. These are physically most consistent with high microporosity objects, though all were on asteroidal-type orbits. We also find three events, including the Oct 8, 2009 airburst near Sulawesi, Indonesia, which display comparatively low heights of peak brightness, consistent with strong monolithic stones or iron meteoroids. Based on orbital similarity, we find a probable connection among several NEOs in our population with the Taurid meteoroid complex. No other major meteoroid streams show linkages with the pre-atmospheric orbits of our meter-class impactors. Our events cover almost four orders of magnitude in mass, but no trend in height of peak brightness is evident, suggesting no strong trend in strength with size for small NEOs, a finding consistent with the results of Popova et al (2011).

Stardust impact analogs: Resolving pre- and postimpact mineralogy in Stardust Al foils

NASA Astrophysics Data System (ADS)

Wozniakiewicz, Penelope J.; Ishii, Hope A.; Kearsley, Anton T.; Burchell, Mark J.; Bradley, John P.; Price, Mark C.; Teslich, Nick; Lee, Martin R.; Cole, Mike J.

2012-04-01

The grains returned by NASA's Stardust mission from comet 81P/Wild 2 represent a valuable sample set that is significantly advancing our understanding of small solar system bodies. However, the grains were captured via impact at ˜6.1 km s-1 and have experienced pressures and temperatures that caused alteration. To ensure correct interpretations of comet 81P/Wild 2 mineralogy, and therefore preaccretional or parent body processes, an understanding of the effects of capture is required. Using a two-stage light-gas gun, we recreated Stardust encounter conditions and generated a series of impact analogs for a range of minerals of cometary relevance into flight spare Al foils. Through analyses of both preimpact projectiles and postimpact analogs by transmission electron microscopy, we explore the impact processes occurring during capture and distinguish between those materials inherent to the impactor and those that are the product of capture. We review existing and present additional data on olivine, diopside, pyrrhotite, and pentlandite. We find that surviving crystalline material is observed in most single grain impactor residues. However, none is found in that of a relatively monodisperse aggregate. A variety of impact-generated components are observed in all samples. Al incorporation into melt-derived phases allows differentiation between melt and shock-induced phases. In single grain impactor residues, impact-generated phases largely retain original (nonvolatile) major element ratios. We conclude that both surviving and impact-generated phases in residues of single grain impactors provide valuable information regarding the mineralogy of the impacting grain whilst further studies are required to fully understand aggregate impacts and the role of subgrain interactions during impact.

Venus - Lakshmi Region

NASA Technical Reports Server (NTRS)

1991-01-01

This Magellan image is centered at 55 degrees north latitude, 348.5 degrees longitude, in the eastern Lakshmi region of Venus. This image, which is of an area 300 kilometers (180 miles) in width and 230 kilometers (138 miles) in length, is a mosaic of orbits 458 through 484. The image shows a relatively flat plains region composed of many lava flows. The dark flows mostly likely represent smooth lava flows similar to 'pahoehoe' flows on Earth while the brighter lava flows are rougher flows similar to 'aa' flows on Earth. (The terms 'pahoehoe' and 'aa' refer to textures of lava with pahoehoe a smooth or ropey surface, and aa a rough, clinkery texture). The rougher flows are brighter because the rough surface returns more energy to the radar than the smooth flows. Situated on top of the lava flows are three dark splotches. Because of the thick Venusian atmosphere, the small impactors break up before they reached the surface. Only the fragments from the broken up impactor are deposited on the surface and these fragments produce the dark splotches in this image. The splotch at the far right (east) has a crater centered in it, indicating that the impactor was not completely destroyed during its journey through the atmosphere. The dark splotches in the center and to the far left in this image each represent an impactor that was broken up into small fragments that did not penetrate the surface to produce a crater. The dark splotch at the left has been modified by the wind. A southwest northeast wind flow has moved some of the debris making up the splotch to the northeast where it has piled up against some small ridges.

Mechanical Design and Analysis of a Unilateral Cervical Spinal Cord Contusion Injury Model in Non-Human Primates

PubMed Central

Salegio, Ernesto A.; Camisa, William; Tam, Horace; Beattie, Michael S.; Bresnahan, Jacqueline C.

2016-01-01

Abstract Non-human primate (NHP) models of spinal cord injury better reflect human injury and provide a better foundation to evaluate potential treatments and functional outcomes. We combined finite element (FE) and surrogate models with impact data derived from in vivo experiments to define the impact mechanics needed to generate a moderate severity unilateral cervical contusion injury in NHPs (Macaca mulatta). Three independent variables (impactor displacement, alignment, and pre-load) were examined to determine their effects on tissue level stresses and strains. Mechanical measures of peak force, peak displacement, peak energy, and tissue stiffness were analyzed as potential determinants of injury severity. Data generated from FE simulations predicted a lateral shift of the spinal cord at high levels of compression (>64%) during impact. Submillimeter changes in mediolateral impactor position over the midline increased peak impact forces (>50%). Surrogate cords established a 0.5 N pre-load protocol for positioning the impactor tip onto the dural surface to define a consistent dorsoventral baseline position before impact, which corresponded with cerebrospinal fluid displacement and entrapment of the spinal cord against the vertebral canal. Based on our simulations, impactor alignment and pre-load were strong contributors to the variable mechanical and functional outcomes observed in in vivo experiments. Peak displacement of 4 mm after a 0.5N pre-load aligned 0.5–1.0 mm over the midline should result in a moderate severity injury; however, the observed peak force and calculated peak energy and tissue stiffness are required to properly characterize the severity and variability of in vivo NHP contusion injuries. PMID:26670940

The Effectiveness of the Component Impact Test Method for the Side Impact Injury Assessment of the Door Trim

NASA Astrophysics Data System (ADS)

Youn, Younghan; Koo, Jeong-Seo

The complete evaluation of the side vehicle structure and the occupant protection is only possible by means of the full scale side impact crash test. But, auto part manufacturers such as door trim makers can not conduct the test especially when the vehicle is under the developing process. The main objective of this study is to obtain the design guidelines by a simple component level impact test. The relationship between the target absorption energy and impactor speed were examined using the energy absorbed by the door trim. Since each different vehicle type required different energy levels on the door trim. A simple impact test method was developed to estimate abdominal injury by measuring reaction force of the impactor. The reaction force will be converted to a certain level of the energy by the proposed formula. The target of absorption energy for door trim only and the impact speed of simple impactor are derived theoretically based on the conservation of energy. With calculated speed of dummy and the effective mass of abdomen, the energy allocated in the abdomen area of door trim was calculated. The impactor speed can be calculated based on the equivalent energy of door trim absorbed during the full crash test. With the proposed design procedure for the door trim by a simple impact test method was demonstrated to evaluate the abdominal injury. This paper describes a study that was conducted to determine sensitivity of several design factors for reducing abdominal injury values using the matrix of orthogonal array method. In conclusion, with theoretical considerations and empirical test data, the main objective, standardization of door trim design using the simple impact test method was established.

Design and testing of a controlled electromagnetic spinal cord impactor for use in large animal models of acute traumatic spinal cord injury.

PubMed

Petteys, Rory J; Spitz, Steven M; Syed, Hasan; Rice, R Andrew; Sarabia-Estrada, Rachel; Goodwin, C Rory; Sciubba, Daniel M; Freedman, Brett A

2017-09-01

Spinal cord injury (SCI) causes debilitating neurological dysfunction and has been observed in warfighters injured in IED blasts. Clinical benefit of SCI treatment remains elusive and better large animal models are needed to assess treatment options. Here, we describe a controlled electromagnetic spinal cord impactor for use in large animal models of SCI. A custom spinal cord impactor and platform were fabricated for large animals (e.g., pig, sheep, dog, etc.). Impacts were generated by a voice coil actuator; force and displacement were measured with a load cell and potentiometer respectively. Labview (National Instruments, Austin, TX) software was used to control the impact cycle and import force and displacement data. Software finite impulse response (FIR) filtering was employed for all input data. Silicon tubing was used a surrogate for spinal cord in order to test the device; repeated impacts were performed at 15, 25, and 40 Newtons. Repeated impacts demonstrated predictable results at each target force. The average duration of impact was 71.2 ±6.1ms. At a target force of 40N, the output force was 41.5 ±0.7N. With a target of 25N, the output force was 23.5 ±0.6N; a target of 15Newtons revealed an output force of 15.2 ±1.4N. The calculated acceleration range was 12.5-21.2m/s 2 . This custom spinal cord impactor reliably delivers precise impacts to the spinal cord and will be utilized in future research to study acute traumatic SCI in a large animal. Published by Elsevier Ltd.

A Parameter Study on the Effect of Impactor Size for NASA’s DART Mission

NASA Astrophysics Data System (ADS)

Truitt, Amanda; Weaver, Robert; Gisler, Galen

2018-06-01

We have modeled the impact of the Double Asteroid Redirection Test (DART) spacecraft into the binary near-Earth asteroid (65803) Didymos. While the primary object is approximately 800 meters across, its secondary body (“moonlet” Didymoon) has a diameter of 150 meters, which is thought to be a much more typical size for the kind of asteroid that would pose a hazard to Earth. DART will be the first demonstration of the kinetic impact technique to change the motion of an asteroid in space, an important consideration for understanding our capabilities in planetary defense of Near-Earth Asteroids. Recent modeling of this impact has used full-density solid aluminum spheres with a mass of approximately 500 kg. Many of the published scaling laws for crater size and diameter as well as ejecta modeling assume this type of impactor, although the actual spacecraft shape being considered for the DART Mission impact is not solid and does not contain a solid dedicated kinetic impactor – rather, the spacecraft itself is considered the impactor. Since the 500 kg hollow spacecraft is significantly larger (~100 x 100 x 200 cm) in size than a solid aluminum sphere (radius ~ 36 cm) the resulting impact dynamics are quite different. Here we have modeled both types of impacts and compare the results of the simulations for crater size, depth, and ejecta for a solid sphere (R = 36 cm) and cylindrical spacecraft (R = 20, 50, and 100 cm), while maintaining a constant mass and material density. This work will allow for a more robust comparison of the momentum enhancement β-factor, which describes the gain in a momentum transfer exerted by the impacting spacecraft on a Near-Earth Object due to ejecta momentum escape. (LA-UR-18-21571)

Los Alamos RAGE Simulations of the HAIV Mission Concept

NASA Technical Reports Server (NTRS)

Weaver, Robert P.; Barbee, Brent W.; Wie, Bong; Zimmerman, Ben

2015-01-01

The mitigation of potentially hazardous objects (PHOs) can be accomplished by a variety of methods including kinetic impactors, gravity tractors and several nuclear explosion options. Depending on the available lead time prior to Earth impact, non- nuclear options can be very effective at altering a PHOs orbit. However if the warning time is short nuclear options are generally deemed most effective at mitigating the hazard. The NIAC mission concept for a nuclear mission has been presented at several meetings, including the last PDC (2013).We use the adaptive mesh hydrocode RAGE to perform detailed simulations of this Hypervelocity Asteroid Intercept Vehicle (HAIV) mission concept. We use the RAGE code to simulate the crater formation by the kinetic impactor as well as the explosion and energy coupling from the follower nuclear explosive device (NED) timed to detonate below the original surface to enhance the energy coupling. The RAGE code has been well validated for a wide variety of applications. A parametric study will be shown of the energy and momentum transfer to the target 100 m diameter object: 1) the HAIV mission as planned; 2) a surface explosion and 3) a subsurface (contained) explosion; both 2) and 3) use the same source energy as 1).Preliminary RAGE simulations show that the kinetic impactor will carve out a surface crater on the object and the subsequent NED explosion at the bottom of the crater transfers energy and momentum to the target effectively moving it off its Earth crossing orbit. Figure 1 shows the initial (simplified) RAGE 2D setup geometry for this study. Figure 2 shows the crater created by the kinetic impactor and Figure 3 shows the time sequence of the energy transfer to the target by the NED.

Cryo-braking using penetrators for enhanced capabilities for the potential landing of payloads on icy solar system objects

NASA Astrophysics Data System (ADS)

Winglee, R. M.; Robinson, T.; Danner, M.; Koch, J.

2018-03-01

The icy moons of Jupiter and Saturn are important astrobiology targets. Access to the surface of these worlds is made difficult by the high ΔV requirements which is typically in the hypervelocity range. Passive braking systems cannot be used due to the lack of an atmosphere, and active braking by rockets significantly adds to the missions costs. This paper demonstrates that a two-stage landing system can overcome these problems and provide significant improvements in the payload fraction that can be landed The first stage involves a hypervelocity impactor which is designed to penetrate to a depth of a few tens of meters. This interaction is the cryo-breaking component and is examined through laboratory experiments, empirical relations and modeling. The resultant ice-particle cloud creates a transient artificial atmosphere that can be used to enable passive braking of the second stage payload dd, with a substantially higher mass payload fraction than possible with a rocket landing system. It is shown that a hollow cylinder design for the impactor can more efficiently eject the material upwards in a solid cone of ice particles relative to solid impactors such as spheres or spikes. The ejected mass is shown to be of the order of 103 to 104 times the mass of the impactor. The modeling indicates that a 10 kg payload with a braking system of 3 m2 (i.e. an areal density of 0.3 kg/m2) is sufficient to allow the landing of the payload with the deceleration limited to less than 2000 g's. Modern electronics can withstand this deceleration and as such the system provides an important alternative to landing payloads on icy solar system objects.

Waves, Plumes and Bubbles from Jupiter Comet Impacts

NASA Astrophysics Data System (ADS)

Palotai, Csaba J.; Sankar, Ramanakumar; McCabe, Tyler; Korycansky, Donald

2017-10-01

We present results from our numerical simulations of jovian comet impacts that investigate various phases of the Shoemaker-Levy 9 (SL9) and the 2009 impacts into Jupiter's atmosphere. Our work includes a linked series of observationally constrained, three-dimensional radiative-hydrodynamic simulations to model the impact, plume blowout, plume flight/splash, and wave-propagation phases of those impact events. Studying these stages using a single model is challenging because the spatial and temporal scales and the temperature range of those phases may differ by orders of magnitudes (Harrington et al. 2004). In our simulations we model subsequent phases starting with the interpolation of the results of previous simulations onto a new, larger grid that is optimized for capturing all key physics of the relevant phenomena while maintaining computational efficiency. This enables us to carry out end-to-end simulations that require no ad-hoc initial conditions. In this work, we focus on the waves generated by various phenomena during the impact event and study the temporal evolution of their position and speed. In particular, we investigate the shocks generated by the impactor during atmospheric entry, the expansion of the ejected plume and the ascent of the hot bubble of material from terminal depth. These results are compared to the observed characteristics of the expanding SL9 rings (Hammel et al. 1995). Additionally, we present results from our sensitivity tests that focus on studying the differences in the ejecta plume generation using various impactor parameters (e.g., impact angle, impactor size, material, etc.). These simulations are used to explain various phenomena related to the SL9 event and to constrain the characteristics of the unknown 2009 impactor body. This research was supported by National Science Foundation Grant AST-1627409.

Constitutive relation for the system-spanning dynamically jammed region in response to impact of cornstarch and water suspensions

NASA Astrophysics Data System (ADS)

Maharjan, Rijan; Mukhopadhyay, Shomeek; Allen, Benjamin; Storz, Tobias; Brown, Eric

2018-05-01

We experimentally characterize the impact response of concentrated suspensions consisting of cornstarch and water. We observe that the suspensions support a large normal stress—on the order of MPa—with a delay after the impactor hits the suspension surface. We show that neither the delay nor the magnitude of the stress can yet be explained by either standard rheological models of shear thickening in terms of steady-state viscosities, or impact models based on added mass or other inertial effects. The stress increase occurs when a dynamically jammed region of the suspension in front of the impactor propagates to the opposite boundary of the container, which can support large stresses when it spans between solid boundaries. We present a constitutive relation for impact rheology to relate the force on the impactor to its displacement. This can be described in terms of an effective modulus but only after the delay required for the dynamically jammed region to span between solid boundaries. Both the modulus and the delay are reported as a function of impact velocity, fluid height, and weight fraction. We report in a companion paper the structure of the dynamically jammed region when it spans between the impactor and the opposite boundary [Allen et al., Phys. Rev. E 97, 052603 (2018), 10.1103/PhysRevE.97.052603]. In a direct follow-up paper, we show that this constitutive model can be used to quantitatively predict, for example, the trajectory and penetration depth of the foot of a person walking or running on cornstarch and water [Mukhopadhyay et al., Phys. Rev. E 97, 052604 (2018), 10.1103/PhysRevE.97.052604].

High efficiency virtual impactor

DOEpatents

Loo, B.W.

1980-03-27

Environmental monitoring of atmospheric air is facilitated by a single stage virtual impactor for separating an inlet flow (Q/sub 0/) having particulate contaminants into a coarse particle flow (Q/sub 1/) and a fine particle flow (Q/sub 2/) to enable collection of such particles on different filters for separate analysis. An inlet particle acceleration nozzle and coarse particle collection probe member having a virtual impaction opening are aligned along a single axis and spaced apart to define a flow separation region at which the fine particle flow (Q/sub 2/) is drawn radially outward into a chamber while the coarse particle flow (Q/sub 1/) enters the virtual impaction opening.

The origin of planetary impactors in the inner solar system.

PubMed

Strom, Robert G; Malhotra, Renu; Ito, Takashi; Yoshida, Fumi; Kring, David A

2005-09-16

Insights into the history of the inner solar system can be derived from the impact cratering record of the Moon, Mars, Venus, and Mercury and from the size distributions of asteroid populations. Old craters from a unique period of heavy bombardment that ended approximately 3.8 billion years ago were made by asteroids that were dynamically ejected from the main asteroid belt, possibly due to the orbital migration of the giant planets. The impactors of the past approximately 3.8 billion years have a size distribution quite different from that of the main belt asteroids but very similar to that of near-Earth asteroids.

Surveying the South Pole-Aitken basin magnetic anomaly for remnant impactor metallic iron

USGS Publications Warehouse

Cahill, Joshua T.S.; Hagerty, Justin J.; Lawrence, David M.; Klima, Rachel L.; Blewett, David T.

2014-01-01

The Moon has areas of magnetized crust ("magnetic anomalies"), the origins of which are poorly constrained. A magnetic anomaly near the northern rim of South Pole-Aitken (SPA) basin was recently postulated to originate from remnant metallic iron emplaced by the SPA basin-forming impactor. Here, we remotely examine the regolith of this SPA magnetic anomaly with a combination of Clementine and Lunar Prospector derived iron maps for any evidence of enhanced metallic iron content. We find that these data sets do not definitively detect the hypothesized remnant metallic iron within the upper tens of centimeters of the lunar regolith.

A NEW CHRONOLOGY FOR THE MOON AND MERCURY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marchi, Simone; Mottola, Stefano; Cremonese, Gabriele

2009-06-15

In this paper, we present a new method for dating the surface of the Moon, obtained by modeling the incoming flux of impactors and converting it into a size distribution of resulting craters. We compare the results from this model with the standard chronology for the Moon showing their similarities and discrepancies. In particular, we find indications of a nonconstant impactor flux in the last 500 Myr and also discuss the implications of our findings for the Late Heavy Bombardment hypothesis. We also show the potential of our model for accurate dating of other inner solar system bodies, by applyingmore » it to Mercury.« less

Various Recrystallizations of CL-20 (HNIW hexanitrohexaazaisowurtzitane).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phillips, Jason Joe

Impact sensitivity testing was performed using a modified Bureau of Mines (MBOM) impactor manufactured by Safety Management Services, Inc., shown in Figure 1. Type-12 tooling was utilized on this machine with a 2.5kg impactor and matching intermediate mass. This particular machine is capable of a maximum drop height of 115cm with 0.1cm increments, though 1cm increments are typically used. Sample material was placed (35 ± 2mg) onto 1 inch squares of Norton brand 180A Garnet sandpaper. Positive results were detected visually or audibly by the operator as smoke, flash, report, charring/tearing of the sandpaper, etc.

Image and compositional characteristics of the LDEF Big Guy impact crater

NASA Technical Reports Server (NTRS)

Bunch, T. E.; Paque, Julie M.; Zolensky, Michael

1995-01-01

A 5.2 mm crater in Al-metal represents the largest found on LDEF. We have examined this crater by field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) and time-of-flight/secondary ion mass spectroscopy (TOF-SIMS) in order to determine if there is any evidence of impactor residue. Droplet and dome-shaped columns, along with flow features, are evidence of melting. EDS from the crater cavity and rim show Mg, C, O and variable amounts of Si, in addition to Al. No evidence for a chondritic impactor was found, and it hypothesized that the crater may be the result of impact with space debris.

Rapid multichannel impact-echo scanning of concrete bridge decks from a continuously moving platform

NASA Astrophysics Data System (ADS)

Mazzeo, Brian A.; Larsen, Jacob; McElderry, Joseph; Guthrie, W. Spencer

2017-02-01

Impact-echo testing is a non-destructive evaluation technique for determining the presence of defects in reinforced concrete bridge decks based on the acoustic response of the bridge deck when struck by an impactor. In this work, we build on our prior research with a single-channel impactor to demonstrate a seven-channel impact-echo scanning system with independent control of the impactors. This system is towed by a vehicle and integrated with distance measurement for registering the locations of the impacts along a bridge deck. The entire impact and recording system is computer-controlled. Because of a winch system and hinged frame construction of the apparatus, setup, measurement, and take-down of the apparatus can be achieved in a matter of minutes. Signal processing of the impact responses is performed on site and can produce a map of delaminations immediately after data acquisition. This map can then be used to guide other testing and/or can be referenced with the results of other testing techniques to facilitate comprehensive condition assessments of concrete bridge decks. This work demonstrates how impact-echo testing can be performed in a manner that makes complete bridge deck scanning for delaminations rapid and practical.

Development of a ginkgo biloba fingerprint chromatogram with UV and evaporative light scattering detection and optimization of the evaporative light scattering detector operating conditions.

PubMed

van Nederkassel, A M; Vijverman, V; Massart, D L; Vander Heyden, Y

2005-09-02

A fingerprint chromatogram of a standardized Ginkgo biloba extract is developed on a monolithic silica column using a ternary gradient containing water, iso-propanol and tetrahydrofuran. For the detection, UV and evaporative light scattering (ELS) detectors are used, the latter allowing detection of the poor UV absorbing compounds as ginkgolides (A-C and J) and bilobalide in the extract. The complementary information between the UV and ELS fingerprint is evaluated. The ELS detector used in this study can operate in an impactor 'on' or 'off' mode. For each mode, the operating conditions such as the nebulizing gas flow rate, the drift tube temperature and the gain are optimized by use of three-level screening designs to obtain the best signal-to-noise (S/N) ratio in the final ELS fingerprint chromatogram. In both impactor modes, very similar S/N ratios are obtained for the nominal levels of the design. However, optimization of the operating conditions resulted, for both impactor modes, in a significant increase in S/N ratios compared to the initial evaluated conditions, obtained from the detector software.

Hydrocode Models of Mitigation of a 170-Meter-Diameter Asteroid Using Energetic Techniques

NASA Astrophysics Data System (ADS)

Plesko, C. S.; Gisler, G. R.; Heberling, T.; Nouanesengsy, B.; Patchett, J.; Sagert, I.; Tarnowsky, T. J.; Weaver, R.

2017-12-01

Binary asteroid 65803 Didymos is the target of the proposed NASA Double Asteroid Redirection Test (DART) mission. The smaller member of the binary pair, S/2003 (65803) Didymos B, is approximately 170 meters in diameter. Didymos A is spectrally similar to H-LL ordinary chondrites and asteroids Eros and Itokawa, so we assume Didymos B is similar. We also assume it to be a rubble pile aggregate of material from Didymos A, and take further guidance on material properties from the AIM Didymos Reference Model V. 10 (P. Michel et al., 2015). We are modeling deflection attempts by kinetic impactor and nuclear stand-off burst against a hypothetical solo Didymos B asteroid as part of the NASA-NNSA inter-agency collaboration on impact hazard mitigation. The collaboration agreed on model initial conditions at our February 2017 Technical Interchange Meeting. The kinetic impactor is a 63.5 cm-diameter aluminum impactor striking at 10 km/s. We model the stand-off nuclear burst according to procedures described in Barbee et al. (Acta A. 2017) and Dearborn et al. (in press). We will present our model predictions and their implications for planetary defense mission design space.

Origin and implications of non-radial Imbrium Sculpture on the Moon.

PubMed

Schultz, Peter H; Crawford, David A

2016-07-21

Rimmed grooves, lineations and elongate craters around Mare Imbrium shape much of the nearside Moon. This pattern was coined the Imbrium Sculpture, and it was originally argued that it must have been formed by a giant oblique (~30°) impact, a conclusion echoed by later studies. Some investigators, however, noticed that many elements of the Imbrium Sculpture are not radial to Imbrium, thereby implicating an endogenic or structural origin. Here we use these non-radial trends to conclude that the Imbrium impactor was a proto-planet (half the diameter of Vesta), once part of a population of large proto-planets in the asteroid belt. Such independent constraints on the sizes of the Imbrium and other basin-forming impactors markedly increase estimates for the mass in the asteroid belt before depletion caused by the orbital migration of Jupiter and Saturn. Moreover, laboratory impact experiments, shock physics codes and the groove widths indicate that multiple fragments (up to 2% of the initial diameter) from each oblique basin-forming impactor, such as the one that formed Imbrium, should have survived planetary collisions and contributed to the heavy impact bombardment between 4.3 and 3.8 billion years ago.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schultz, Peter H.; Crawford, David A.

Rimmed grooves, lineations and elongate craters around Mare Imbrium shape much of the nearside Moon. This pattern was coined the Imbrium Sculpture 1, and it was originally argued that it must have been formed by a giant oblique (~30°) impact, a conclusion echoed by later studies 2. Some investigators, however, noticed that many elements of the Imbrium Sculpture are not radial to Imbrium, thereby implicating an endogenic or structural origin 3, 4. Here we use these non-radial trends to conclude that the Imbrium impactor was a proto-planet (half the diameter of Vesta), once part of a population of large proto-planetsmore » in the asteroid belt. Such independent constraints on the sizes of the Imbrium and other basin-forming impactors markedly increase estimates for the mass in the asteroid belt before depletion caused by the orbital migration of Jupiter and Saturn 5. Furthermore, laboratory impact experiments, shock physics codes and the groove widths indicate that multiple fragments (up to 2% of the initial diameter) from each oblique basin-forming impactor, such as the one that formed Imbrium, should have survived planetary collisions and contributed to the heavy impact bombardment between 4.3 and 3.8 billion years ago.« less

Origin and implications of non-radial Imbrium Sculpture on the Moon

NASA Astrophysics Data System (ADS)

Schultz, Peter H.; Crawford, David A.

2016-07-01

Rimmed grooves, lineations and elongate craters around Mare Imbrium shape much of the nearside Moon. This pattern was coined the Imbrium Sculpture, and it was originally argued that it must have been formed by a giant oblique (~30°) impact, a conclusion echoed by later studies. Some investigators, however, noticed that many elements of the Imbrium Sculpture are not radial to Imbrium, thereby implicating an endogenic or structural origin. Here we use these non-radial trends to conclude that the Imbrium impactor was a proto-planet (half the diameter of Vesta), once part of a population of large proto-planets in the asteroid belt. Such independent constraints on the sizes of the Imbrium and other basin-forming impactors markedly increase estimates for the mass in the asteroid belt before depletion caused by the orbital migration of Jupiter and Saturn. Moreover, laboratory impact experiments, shock physics codes and the groove widths indicate that multiple fragments (up to 2% of the initial diameter) from each oblique basin-forming impactor, such as the one that formed Imbrium, should have survived planetary collisions and contributed to the heavy impact bombardment between 4.3 and 3.8 billion years ago.

Fluid mechanical scaling of impact craters in unconsolidated granular materials

NASA Astrophysics Data System (ADS)

Miranda, Colin S.; Dowling, David R.

2015-11-01

A single scaling law is proposed for the diameter of simple low- and high-speed impact craters in unconsolidated granular materials where spall is not apparent. The scaling law is based on the assumption that gravity- and shock-wave effects set crater size, and is formulated in terms of a dimensionless crater diameter, and an empirical combination of Froude and Mach numbers. The scaling law involves the kinetic energy and speed of the impactor, the acceleration of gravity, and the density and speed of sound in the target material. The size of the impactor enters the formulation but divides out of the final empirical result. The scaling law achieves a 98% correlation with available measurements from drop tests, ballistic tests, missile impacts, and centrifugally-enhanced gravity impacts for a variety of target materials (sand, alluvium, granulated sugar, and expanded perlite). The available measurements cover more than 10 orders of magnitude in impact energy. For subsonic and supersonic impacts, the crater diameter is found to scale with the 1/4- and 1/6-power, respectively, of the impactor kinetic energy with the exponent crossover occurring near a Mach number of unity. The final empirical formula provides insight into how impact energy partitioning depends on Mach number.

A Dragonfly-Shaped Crater

NASA Image and Video Library

2017-02-10

The broader scene for this image is the fluidized ejecta from Bakhuysen Crater to the southwest, but there's something very interesting going on here on a much smaller scale. A small impact crater, about 25 meters in diameter, with a gouged-out trench extends to the south. The ejecta (rocky material ejected from the crater) mostly extends to the east and west of the crater. This "butterfly" ejecta is very common for craters formed at low impact angles. Taken together, these observations suggest that the crater-forming impactor came in at a low angle from the north, hit the ground and ejected material to the sides. The top of the impactor may have sheared off ("decapitating" the impactor) and continued downrange, forming the trench. We can't prove that's what happened, but this explanation is consistent with the observations. Regardless of how it formed, it's quite an interesting-looking "dragonfly" crater. The map is projected here at a scale of 50 centimeters (19.69 inches) per pixel. [The original image scale is 55.7 centimeters (21.92 inches) per pixel (with 2 x 2 binning); objects on the order of 167 centimeters (65.7 inches) across are resolved.] North is up. http://photojournal.jpl.nasa.gov/catalog/PIA21454

Cataclysm No More: New Views on the Timing and Delivery of Lunar Impactors.

PubMed

Zellner, Nicolle E B

2017-09-01

If properly interpreted, the impact record of the Moon, Earth's nearest neighbour, can be used to gain insights into how the Earth has been influenced by impacting events since its formation ~4.5 billion years (Ga) ago. However, the nature and timing of the lunar impactors - and indeed the lunar impact record itself - are not well understood. Of particular interest are the ages of lunar impact basins and what they tell us about the proposed "lunar cataclysm" and/or the late heavy bombardment (LHB), and how this impact episode may have affected early life on Earth or other planets. Investigations of the lunar impactor population over time have been undertaken and include analyses of orbital data and images; lunar, terrestrial, and other planetary sample data; and dynamical modelling. Here, the existing information regarding the nature of the lunar impact record is reviewed and new interpretations are presented. Importantly, it is demonstrated that most evidence supports a prolonged lunar (and thus, terrestrial) bombardment from ~4.2 to 3.4 Ga and not a cataclysmic spike at ~3.9 Ga. Implications for the conditions required for the origin of life are addressed.

Calibration of thin-foil manganin gauge in ALOX material

NASA Astrophysics Data System (ADS)

Benham, R. A.; Weirick, L. J.; Lee, L. M.

1996-05-01

The purpose of this program was to develop a calibration curve (stress as a function of change in gauge resistance/gauge resistance) and to obtain gauge repeatability data for Micro-Measurements stripped manganin thin-foiled gauges up to 6.1 GPa in ALOX (42% by volume alumina in Epon 828 epoxy) material. A light-gas gun was used to drive an ALOX impactor into the ALOX target containing four gauges in a centered diamond arrangement. Tilt and velocity of the impactor were measured along with the gauge outputs. Impact stresses from 0.5 to 6.1 GPa were selected in increments of 0.7 GPa with duplicate tests done at 0.5, 3.3 and 6.1 GPa. A total of twelve tests was conducted using ALOX. Three initial tests were done using polymethyl methacrylate (PMMA) as the impactor and target at an impact pressure of 3.0 GPa for comparison of gauge output with analysis and literature values. The installed gauge, stripped of its backing, has a nominal thickness of 5 μm. The thin gauge and high speed instrumentation allowed higher time resolution measurements than can be obtained with manganin wire.

Meteorite crater impact study: a new way to study seismology at school with exciting experiments, and an example of meteorite astroblema in France (Rochechouart)

NASA Astrophysics Data System (ADS)

Carrer, Diane; Berenguer, Jean-Luc; MacMurray, Andrew

2016-04-01

The InSIGHT mission to Mars (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) supported by NASA, IPGP and CNES, is a great opportunity for teachers and pupils to study the Red planet, but also to study other fields of geology at school, such as seismology. With our pupils, we are following the InSight mission and we look forward to analyze seismic data registered by the SEIS seismometer , once it will be available (the InSight mission will launch in 2018 from California, and will land to Mars in 2018 or 2019). As this mission needs meteorite impacts to generate seismic waves ( to discover the Martian interior structure) , we've decided to model those meteorite strikes in the classroom. With our pupils, we've modeled meteorite impact craters with different impactors , such as tennis balls, baseballs, or pingpong balls, and used an analogue substratum made by flour and cocoa. Then, we kept on going our geophysical investigation , studying several parameters. For instance, we've studied the link between size of impactor and size of crater , the link between mass of impactor and Crater Formation, and the link between velocity of impactor and crater formation. In this geophysical approach , potential energy and kinetic energy can be introduced in terms of energy transfer as the impactor falls ( calculation of the velocity of impact and plotting that against crater diameter using v = (2gh)1/2). For each crater formation made in class by students, we have registered seismological data thanks to Audacity software, and study the seismic signal propagation. This exemple of hands-on activity with pupils, and its wide range of geophysical calculation shows how we can do simple experiment modeling meteorite crater impact and exploit registered seismological data at school. We've finaly focused our work with the very famous example of the astroblema of Rochechouart in the South-west of France ( crater formation : - 214 My) , in which it's easy to recognize every typical structure of crater formation (ejecta blankets, overturned crater rim) . In this activity, pupils understand how a model in class can be close to real geological objects.

Improving the UNC Passive Aerosol Sampler Model Based on Comparison with Commonly Used Aerosol Sampling Methods.

PubMed

Shirdel, Mariam; Andersson, Britt M; Bergdahl, Ingvar A; Sommar, Johan N; Wingfors, Håkan; Liljelind, Ingrid E

2018-03-12

In an occupational environment, passive sampling could be an alternative to active sampling with pumps for sampling of dust. One passive sampler is the University of North Carolina passive aerosol sampler (UNC sampler). It is often analysed by microscopic imaging. Promising results have been shown for particles above 2.5 µm, but indicate large underestimations for PM2.5. The aim of this study was to evaluate, and possibly improve, the UNC sampler for stationary sampling in a working environment. Sampling was carried out at 8-h intervals during 24 h in four locations in an open pit mine with UNC samplers, respirable cyclones, PM10 and PM2.5 impactors, and an aerodynamic particle sizer (APS). The wind was minimal. For quantification, two modifications of the UNC sampler analysis model, UNC sampler with hybrid model and UNC sampler with area factor, were compared with the original one, UNC sampler with mesh factor derived from wind tunnel experiments. The effect of increased resolution for the microscopic imaging was examined. Use of the area factor and a higher resolution eliminated the underestimation for PM10 and PM2.5. The model with area factor had the overall lowest deviation versus the impactor and the cyclone. The intraclass correlation (ICC) showed that the UNC sampler had a higher precision and better ability to distinguish between different exposure levels compared to the cyclone (ICC: 0.51 versus 0.24), but lower precision compared to the impactor (PM10: 0.79 versus 0.99; PM2.5: 0.30 versus 0.45). The particle size distributions as calculated from the different UNC sampler analysis models were visually compared with the distributions determined by APS. The distributions were obviously different when the UNC sampler with mesh factor was used but came to a reasonable agreement when the area factor was used. High resolution combined with a factor based on area only, results in no underestimation of small particles compared to impactors and cyclones and a better agreement with the APS's particle size distributions. The UNC sampler had lower precision than the impactors, but higher than the respirable cyclone. The UNC sampler with area factor could be used for PM2.5, PM10 and respirable fraction measurements in this working environment without wind.

Improving the UNC Passive Aerosol Sampler Model Based on Comparison with Commonly Used Aerosol Sampling Methods

PubMed Central

Shirdel, Mariam; Andersson, Britt M; Bergdahl, Ingvar A; Sommar, Johan N; Wingfors, Håkan; Liljelind, Ingrid E

2018-01-01

Abstract Objectives In an occupational environment, passive sampling could be an alternative to active sampling with pumps for sampling of dust. One passive sampler is the University of North Carolina passive aerosol sampler (UNC sampler). It is often analysed by microscopic imaging. Promising results have been shown for particles above 2.5 µm, but indicate large underestimations for PM2.5. The aim of this study was to evaluate, and possibly improve, the UNC sampler for stationary sampling in a working environment. Methods Sampling was carried out at 8-h intervals during 24 h in four locations in an open pit mine with UNC samplers, respirable cyclones, PM10 and PM2.5 impactors, and an aerodynamic particle sizer (APS). The wind was minimal. For quantification, two modifications of the UNC sampler analysis model, UNC sampler with hybrid model and UNC sampler with area factor, were compared with the original one, UNC sampler with mesh factor derived from wind tunnel experiments. The effect of increased resolution for the microscopic imaging was examined. Results Use of the area factor and a higher resolution eliminated the underestimation for PM10 and PM2.5. The model with area factor had the overall lowest deviation versus the impactor and the cyclone. The intraclass correlation (ICC) showed that the UNC sampler had a higher precision and better ability to distinguish between different exposure levels compared to the cyclone (ICC: 0.51 versus 0.24), but lower precision compared to the impactor (PM10: 0.79 versus 0.99; PM2.5: 0.30 versus 0.45). The particle size distributions as calculated from the different UNC sampler analysis models were visually compared with the distributions determined by APS. The distributions were obviously different when the UNC sampler with mesh factor was used but came to a reasonable agreement when the area factor was used. Conclusions High resolution combined with a factor based on area only, results in no underestimation of small particles compared to impactors and cyclones and a better agreement with the APS’s particle size distributions. The UNC sampler had lower precision than the impactors, but higher than the respirable cyclone. The UNC sampler with area factor could be used for PM2.5, PM10 and respirable fraction measurements in this working environment without wind. PMID:29300818

Earth Impact Effects Program: Estimating the Regional Environmental Consequences of Impacts On Earth

NASA Astrophysics Data System (ADS)

Collins, G. S.; Melosh, H. J.; Marcus, R. A.

2009-12-01

The Earth Impact Effects Program (www.lpl.arizona.edu/impacteffects) is a popular web-based calculator for estimating the regional environmental consequences of a comet or asteroid impact on Earth. It is widely used, both by inquisitive members of the public as an educational device and by scientists as a simple research tool. It applies a variety of scaling laws, based on theory, nuclear explosion test data, observations from terrestrial and extraterrestrial craters and the results of small-scale impact experiments and numerical modelling, to quantify the principal hazards that might affect the people, buildings and landscape in the vicinity of an impact. The program requires six inputs: impactor diameter, impactor density, impact velocity prior to atmospheric entry, impact angle, and the target type (sedimentary rock, crystalline rock, or a water layer above rock), as well as the distance from the impact at which the environmental effects are to be calculated. The program includes simple algorithms for estimating the fate of the impactor during atmospheric traverse, the thermal radiation emitted by the impact plume (fireball) and the intensity of seismic shaking. The program also approximates various dimensions of the impact crater and ejecta deposit, as well as estimating the severity of the air blast in both crater-forming and airburst impacts. We illustrate the strengths and limitations of the program by comparing its predictions (where possible) against known impacts, such as Carancas, Peru (2007); Tunguska, Siberia (1908); Barringer (Meteor) crater, Arizona (ca 49 ka). These tests demonstrate that, while adequate for large impactors, the simple approximation of atmospheric entry in the original program does not properly account for the disruption and dispersal of small impactors as they traverse Earth's atmosphere. We describe recent improvements to the calculator to better describe atmospheric entry of small meteors; the consequences of oceanic impacts; and the recurrance interval between impacts of a given size. In addition, we assess the potential regional hazard of hypothetical impact scenarios of different scales. Our simple calculator suggests that the most wide-reaching regional hazard is seismic shaking: both ejecta-deposit thickness and airblast pressure decay much more rapidly with distance than seismic ground motion. Close to the impact site the most severe hazard is from thermal radiation; however, the curvature of the Earth implies that distant localities are shielded from direct thermal radiation because the fireball is below the horizon.

Use of an HIV-risk screening tool to identify optimal candidates for PrEP scale-up among men who have sex with men in Toronto, Canada: disconnect between objective and subjective HIV risk.

PubMed

Wilton, James; Kain, Taylor; Fowler, Shawn; Hart, Trevor A; Grennan, Troy; Maxwell, John; Tan, Darrell Hs

2016-01-01

Identifying appropriate pre-exposure prophylaxis (PrEP) candidates is a challenge in planning for the safe and effective roll-out of this strategy. We explored the use of a validated HIV risk screening tool, HIV Incidence Risk Index for Men who have Sex with Men (HIRI-MSM), to identify "optimal" candidates among MSM testing at a busy sexual health clinic's community testing sites in Toronto, Canada. Between November 2014 and April 2015, we surveyed MSM undergoing anonymous HIV testing at community testing sites in Toronto, Canada, to quantify "optimal" candidates for scaling up PrEP roll-out, defined as being at high objective HIV risk (scoring ≥10 on the HIRI-MSM), perceiving oneself at moderate-to-high HIV risk and being willing to use PrEP. Cascades were constructed to identify barriers to broader PrEP uptake. The association between HIRI-MSM score and both willingness to use PrEP and perceived HIV risk were explored in separate multivariable logistic regression analyses. Of 420 respondents, 64.4% were objectively at high risk, 52.5% were willing to use PrEP and 27.2% perceived themselves at moderate-to-high HIV risk. Only 16.4% were "optimal" candidates. Higher HIRI-MSM scores were positively associated with both willingness to use PrEP (aOR=1.7 per 10 score increase, 95%CI=1.3-2.2) and moderate-to-high perceived HIV risk (aOR=1.7 per 10 score increase, 95%CI=1.2-2.3). The proportion of men who were "optimal" candidates increased to 42.9% when the objective HIV risk cut-off was changed to top quartile of HIRI-MSM scores (≥26). In our full cascade, a very low proportion (5.3%) of MSM surveyed could potentially benefit from PrEP under current conditions. The greatest barrier in the cascade was low perception of HIV risk among high-risk men, but considerable numbers were also lost in downstream cascade steps. Of men at high objective HIV risk, 68.3% did not perceive themselves to be at moderate-to-high HIV risk, 23.6% were unaware of PrEP, 40.1% were not willing to use PrEP, 47.6% lacked a family physician with whom they felt comfortable discussing sexual health, and 31.6% had no means to cover the cost of PrEP. A higher HIRI-MSM cut-off may be helpful for identifying candidates for PrEP scale-up. Improving engagement in the PrEP cascade will require interventions to simultaneously address multiple barriers.

Use of an HIV-risk screening tool to identify optimal candidates for PrEP scale-up among men who have sex with men in Toronto, Canada: disconnect between objective and subjective HIV risk

PubMed Central

Wilton, James; Kain, Taylor; Fowler, Shawn; Hart, Trevor A; Grennan, Troy; Maxwell, John; Tan, Darrell HS

2016-01-01

Introduction Identifying appropriate pre-exposure prophylaxis (PrEP) candidates is a challenge in planning for the safe and effective roll-out of this strategy. We explored the use of a validated HIV risk screening tool, HIV Incidence Risk Index for Men who have Sex with Men (HIRI-MSM), to identify “optimal” candidates among MSM testing at a busy sexual health clinic's community testing sites in Toronto, Canada. Methods Between November 2014 and April 2015, we surveyed MSM undergoing anonymous HIV testing at community testing sites in Toronto, Canada, to quantify “optimal” candidates for scaling up PrEP roll-out, defined as being at high objective HIV risk (scoring ≥10 on the HIRI-MSM), perceiving oneself at moderate-to-high HIV risk and being willing to use PrEP. Cascades were constructed to identify barriers to broader PrEP uptake. The association between HIRI-MSM score and both willingness to use PrEP and perceived HIV risk were explored in separate multivariable logistic regression analyses. Results Of 420 respondents, 64.4% were objectively at high risk, 52.5% were willing to use PrEP and 27.2% perceived themselves at moderate-to-high HIV risk. Only 16.4% were “optimal” candidates. Higher HIRI-MSM scores were positively associated with both willingness to use PrEP (aOR=1.7 per 10 score increase, 95%CI=1.3–2.2) and moderate-to-high perceived HIV risk (aOR=1.7 per 10 score increase, 95%CI=1.2–2.3). The proportion of men who were “optimal” candidates increased to 42.9% when the objective HIV risk cut-off was changed to top quartile of HIRI-MSM scores (≥26). In our full cascade, a very low proportion (5.3%) of MSM surveyed could potentially benefit from PrEP under current conditions. The greatest barrier in the cascade was low perception of HIV risk among high-risk men, but considerable numbers were also lost in downstream cascade steps. Of men at high objective HIV risk, 68.3% did not perceive themselves to be at moderate-to-high HIV risk, 23.6% were unaware of PrEP, 40.1% were not willing to use PrEP, 47.6% lacked a family physician with whom they felt comfortable discussing sexual health, and 31.6% had no means to cover the cost of PrEP. Conclusions A higher HIRI-MSM cut-off may be helpful for identifying candidates for PrEP scale-up. Improving engagement in the PrEP cascade will require interventions to simultaneously address multiple barriers. PMID:27265490

Characterizing a Quantum Cascade Tunable Infrared Laser Differential Absorption Spectrometer (QC-TILDAS) for Measurements of Atmospheric Ammonia

NASA Astrophysics Data System (ADS)

Ellis, R.; Murphy, J. G.; van Haarlem, R.; Pattey, E.; O'Brien, J.

2009-05-01

A compact, fast response Quantum Cascade Tunable Infrared Laser Differential Absorption Spectrometer (QC- TILDAS) for measurements of ammonia has been evaluated under both laboratory and field conditions. Absorption of radiation from a pulsed, thermoelectrically cooled QC laser occurs at reduced pressure in a 76 m path length, 0.5 L volume multiple pass absorption cell. Detection is achieved using a thermoelectrically cooled HgCdTe infrared detector. A novel sampling technique was used, consisting of a short, heated, quartz inlet with a hydrophobic coating to minimize the adsorption of ammonia to surfaces. The inlet contains a critical orifice that reduces the pressure, a virtual impactor for separation of particles and additional ports for delivering ammonia free background air and calibration gas standards. This instrument has been found to have a detection limit of 0.3 ppb with a time resolution of 1 s. The sampling technique has been compared to the results of a conventional lead salt Tunable Diode Laser (TDL) absorption spectrometer during a laboratory intercomparison. Various lengths and types of sample inlet tubing material, heated and unheated, under dry and ambient humidity conditions with ammonia concentrations ranging from 10-1000 ppb were investigated. Preliminary analysis suggests the time response improves with the use of short, PFA tubing sampling lines. No significant improvement was observed when using a heated sampling line and humidity was seen to play an important role on the bi-exponential decay of ammonia. A field intercomparison of the QC-TILDAS with a modified Thermo 42C chemiluminescence based analyzer was also performed at Environment Canada's Centre for Atmospheric Research Experiments (CARE) in the rural town of Egbert, ON between May-July 2008. Background tests and calibrations using two different permeation tube sources and an ammonia gas cylinder were regularly carried out throughout the study. Results indicate a very good correlation (r2>0.9) between the two instruments at the beginning of the study, when regular background subtraction was applied to the QC- TILDAS.

Centrifuge Impact Cratering Experiments

NASA Technical Reports Server (NTRS)

Schmidt, R. M.; Housen, K. R.; Bjorkman, M. D.

1985-01-01

The kinematics of crater growth, impact induced target flow fields and the generation of impact melt were determined. The feasibility of using scaling relationships for impact melt and crater dimensions to determine impactor size and velocity was studied. It is concluded that a coupling parameter determines both the quantity of melt and the crater dimensions for impact velocities greater than 10km/s. As a result impactor radius, a, or velocity, U cannot be determined individually, but only as a product in the form of a coupling parameter, delta U micron. The melt volume and crater volume scaling relations were applied to Brent crater. The transport of melt and the validity of the melt volume scaling relations are examined.

Meteorological transport of continental soot to Antarctica?

NASA Astrophysics Data System (ADS)

Murphey, B. B.; Hogan, A. W.

1992-01-01

An impactor/concentrator/microdensitometer (ICM) instrument system has been constructed and calibrated. This system is sufficiently sensitive to measure the black (carbon soot) component of Antarctic aerosol with a sampling time of four hours. The impactor concentrator was exposed to Antarctic air at Ross Island in September 1987. Microdensitometer analysis of the collected specimens indicates that the maximum black aerosol concentration was observed concurrently with the arrival of the warmest air accompanying a cyclonic storm. This is similar to the concurrence of continental radon and lead isotopes with warm advection, measured on the Antarctic coast by Polian et al. (1986). It is possible that continental soot can be transported to the Antarctic coast several times each year by this mechanism.

Kinetic Damage from Meteorites

NASA Technical Reports Server (NTRS)

Cooke, W.; Brown, P.; Matney, M.

2017-01-01

Comparing the natural meteorite flux at the Earth's surface to that of space debris, re-entering debris is 2 orders of magnitude less of a kinetic hazard at all but the very largest (and therefore rarest) sizes compared to natural impactors. Debris re-entries over several metric tonnes are roughly as frequent as natural impactors, but the survival fraction is expected to be much higher. Kinetic hazards from meteorites are very small, with only one recorded (indirect) injury reported. We expect fatalities to be even more rare, on the order of one person killed per several millennia. That several reports exist of small fragments/sand hitting people during meteorite falls is consistent with our prediction that this should occur every decade or so.

Kinetic Damage from Meteorites

NASA Technical Reports Server (NTRS)

Cooke, W.; Matney, M.; Brown, P.

2017-01-01

Comparing the natural meteorite flux at the Earth's surface to that of space debris, reentering debris is approx. 2 orders of magnitude less of a kinetic hazard at all but the very largest (and therefore rarest) sizes compared to natural impactors. Debris re-entries over several metric tonnes are roughly as frequent as natural impactors, but the survival fraction is expected to be much higher. Kinetic hazards from meteorites are very small, with only one recorded (indirect) injury reported. We expect fatalities to be even more rare, on the order of one person killed per several millennia. That several reports exist of small fragments/sand hitting people during meteorite falls is consistent with our prediction that this should occur every decade or so.

Survival of the impactor during hypervelocity collisions - II. An analogue for high-porosity targets

NASA Astrophysics Data System (ADS)

Avdellidou, C.; Price, M. C.; Delbo, M.; Cole, M. J.

2017-01-01

We investigated how a target's porosity affects the outcome of a collision, with respect to the impactor's fate. Laboratory impact experiments using peridot projectiles were performed at a speed range between 0.3 and 3.0 km s-1, on to high-porosity water-ice (40 per cent) and fine-grained calcium carbonate (70 per cent) targets. We report that the amount of implanted material in the target body increases with increasing target's porosity, while the size frequency distribution of the projectile's ejecta fragments becomes steeper. A supplementary Raman study showed no sign of change of the Raman spectra of the recovered olivine projectile fragments indicate minimal physical change.

An Ordinary Chondrite Impactor Composition for the Bosumtwi Impact Structure, Ghana, West Africa: Discussion of Siderophile Element Contents and Os and Cr Isotope Data

NASA Technical Reports Server (NTRS)

Koeberl, Christian; Shukolyukov, Alex; Lugmair, Guenter

2004-01-01

Osmium isotope data had shown that Ivory Coast tektites contain an extraterrestrial component, but do not allow distinction between chondritic and iron meteorite contamination. PGE abundances of Ivory Coast tektites and impactites and target rocks from the Bosumtwi crater, the source crater of the Ivory Coast tektites, were all relatively high and did not allow to resolve the presence, or identify the nature, of the meteoritic component. However, Cr isotope analyses of an Ivory Coast tektite yielded a distinct 53Cr excess of 0.30+/-0.06, which indicates that the Bosumtwi impactor was an ordinary chondrite.

Hypervelocity sub 10-micron impacts into aluminium foil: new experimental data and implications for comet 81P/Wild-2's dust fluence

NASA Astrophysics Data System (ADS)

Price, Mark C.; Kearsley, Anton T.; Burchell, Mark J.; Horz, Friedrich; Cole, Mike J.

2009-06-01

Recent experimental work (Price, M. C. et. al., LPSC XXXX, #1564, 2009) has shown that the lip-to-lip diameter of hypervelocity impact craters at micron-scales (Dp< 10 microns) is a non-linear function of the impactor's diameter (Dp). We present data for monodisperse silica projectiles impacting aluminium-1100 and elemental aluminium at 6.1 kmsec and discuss the implications of this effect for the Stardust fluence calibration for micron-scale particles (which make up the majority of the impactor flux). Hydrocodes have been used to investigate the potential causes of the phenomena and the results are presented.

Low and high velocity impact response of thick hybrid composites

NASA Technical Reports Server (NTRS)

Hiel, Clement; Ishai, Ori

1993-01-01

The effects of low and high velocity impact on thick hybrid composites (THC's) were experimentally compared. Test Beams consisted of CFRP skins which were bonded onto an interleaved syntactic foam core and cured at 177 C (350 F). The impactor tip for both cases was a 16 mm (0.625 inch) steel hemisphere. In spite of the order of magnitude difference in velocity ranges and impactor weights, similar relationships between impact energy, damage size, and residual strength were found. The dependence of the skin compressive strength on damage size agree well with analytical open hole models for composite laminates and may enable the prediction of ultimate performance for the damaged composite, based on visual inspection.

Flight Operations for the LCROSS Lunar Impactor Mission

NASA Technical Reports Server (NTRS)

Tompkins, Paul D.; Hunt, Rusty; D'Ortenzio, Matt D.; Strong, James; Galal, Ken; Bresina, John L.; Foreman, Darin; Barber, Robert; Shirley, Mark; Munger, James;

Hemodynamic and tubular changes induced by contrast media.

PubMed

Caiazza, Antonella; Russo, Luigi; Sabbatini, Massimo; Russo, Domenico

2014-01-01

The incidence of acute kidney injury induced by contrast media (CI-AKI) is the third cause of AKI in hospitalized patients. Contrast media cause relevant alterations both in renal hemodynamics and in renal tubular cell function that lead to CI-AKI. The vasoconstriction of intrarenal vasculature is the main hemodynamic change induced by contrast media; the vasoconstriction is accompanied by a cascade of events leading to ischemia and reduction of glomerular filtration rate. Cytotoxicity of contrast media causes apoptosis of tubular cells with consequent formation of casts and worsening of ischemia. There is an interplay between the negative effects of contrast media on renal hemodynamics and on tubular cell function that leads to activation of renin-angiotensin system and increased production of reactive oxygen species (ROS) within the kidney. Production of ROS intensifies cellular hypoxia through endothelial dysfunction and alteration of mechanisms regulating tubular cells transport. The physiochemical characteristics of contrast media play a critical role in the incidence of CI-AKI. Guidelines suggest the use of either isoosmolar or low-osmolar contrast media rather than high-osmolar contrast media particularly in patients at increased risk of CI-AKI. Older age, presence of atherosclerosis, congestive heart failure, chronic renal disease, nephrotoxic drugs, and diuretics may multiply the risk of CI-AKI.

Hemodynamic and Tubular Changes Induced by Contrast Media

PubMed Central

Caiazza, Antonella; Russo, Luigi; Russo, Domenico

2014-01-01

The incidence of acute kidney injury induced by contrast media (CI-AKI) is the third cause of AKI in hospitalized patients. Contrast media cause relevant alterations both in renal hemodynamics and in renal tubular cell function that lead to CI-AKI. The vasoconstriction of intrarenal vasculature is the main hemodynamic change induced by contrast media; the vasoconstriction is accompanied by a cascade of events leading to ischemia and reduction of glomerular filtration rate. Cytotoxicity of contrast media causes apoptosis of tubular cells with consequent formation of casts and worsening of ischemia. There is an interplay between the negative effects of contrast media on renal hemodynamics and on tubular cell function that leads to activation of renin-angiotensin system and increased production of reactive oxygen species (ROS) within the kidney. Production of ROS intensifies cellular hypoxia through endothelial dysfunction and alteration of mechanisms regulating tubular cells transport. The physiochemical characteristics of contrast media play a critical role in the incidence of CI-AKI. Guidelines suggest the use of either isoosmolar or low-osmolar contrast media rather than high-osmolar contrast media particularly in patients at increased risk of CI-AKI. Older age, presence of atherosclerosis, congestive heart failure, chronic renal disease, nephrotoxic drugs, and diuretics may multiply the risk of CI-AKI. PMID:24678510

Origin and implications of non-radial Imbrium Sculpture on the Moon

DOE PAGES

Schultz, Peter H.; Crawford, David A.

2016-07-20

Rimmed grooves, lineations and elongate craters around Mare Imbrium shape much of the nearside Moon. This pattern was coined the Imbrium Sculpture 1, and it was originally argued that it must have been formed by a giant oblique (~30°) impact, a conclusion echoed by later studies 2. Some investigators, however, noticed that many elements of the Imbrium Sculpture are not radial to Imbrium, thereby implicating an endogenic or structural origin 3, 4. Here we use these non-radial trends to conclude that the Imbrium impactor was a proto-planet (half the diameter of Vesta), once part of a population of large proto-planetsmore » in the asteroid belt. Such independent constraints on the sizes of the Imbrium and other basin-forming impactors markedly increase estimates for the mass in the asteroid belt before depletion caused by the orbital migration of Jupiter and Saturn 5. Furthermore, laboratory impact experiments, shock physics codes and the groove widths indicate that multiple fragments (up to 2% of the initial diameter) from each oblique basin-forming impactor, such as the one that formed Imbrium, should have survived planetary collisions and contributed to the heavy impact bombardment between 4.3 and 3.8 billion years ago.« less

Flash heating on the early Earth.

PubMed

Lyons, J R; Vasavada, A R

1999-03-01

It has been suggested that very large impact events (approximately 500 km diameter impactors) sterilized the surface of the young Earth by producing enough rock vapor to boil the oceans. Here, we consider surface heating due to smaller impactors, and demonstrate that surface temperatures conductive to organic synthesis resulted. In particular, we focus on the synthesis of thermal peptides. Previously, laboratory experiments have demonstrated that dry heating a mixture of amino acids containing excess Asp, Glu, or Lys to temperatures approximately 170 degrees C for approximately 2 hours yields polypeptides. It has been argued that such temperature conditions would not have been available on the early Earth. Here we demonstrate, by analogy with the K/T impact, that the requisite temperatures are achieved on sand surfaces during the atmospheric reentry of fine ejecta particles produced by impacts of bolides approximately 10-20 km in diameter, assuming approximately 1-100 PAL CO2. Impactors of this size struck the Earth with a frequency of approximately 1 per 10(4)-10(5) y at 4.2 Ga. Smaller bolides produced negligible global surface heating, whereas bolides > 30 km in diameter yielded solid surface temperatures > 1000 K, high enough to pyrolyze amino acids and other organic compounds. Thus, peptide formation would have occurred globally for a relatively narrow range of bolide sizes.

Estimates of Comet Fragment Masses from Impact Crater Chains on Callisto and Ganymede

NASA Technical Reports Server (NTRS)

McKinnon, William B.; Schenk, Paul M.

1995-01-01

Chains of impact craters, or catenae, have been identified in Voyager images of Callisto and Ganymede. Although these resemble in some respects secondary crater chains, the source craters and basins for the catenae cannot be identified. The best explanation is a phenomenon similar to that displayed by former comet Shoemaker-Levy 9; tidal (or other) breakup close to Jupiter followed by gradual orbital separation of the fragments and collision with a Galilean satellite on the outbound leg of the trajectory. Because the trajectories must pass close to Jupiter, this constrains the impact geometry (velocity and impact angle) of the individual fragments. For the dominant classes of impactors, short period Jupiter-family comets and asteroids, velocities at Callisto and Ganymede are dominated by Jovian gravity and a satellite's orbital motion, and are insensitive to the pre-fragmentation heliocentric velocity; velocities are insensitive to satellite gravity for all impactor classes. Complex crater shapes on Callisto and Ganymede are determined from Voyager images and Schmidt-Holsapple scaling is used to back out individual fragment masses. We find that comet fragment radii are generally less than about 500 m (for ice densities) but can be larger. These estimates can be compared with those for the Shoemaker-Levy 9 impactors.

Orbital Debris Shape and Orientation Effects on Impact Damage to Shuttle Tiles

NASA Technical Reports Server (NTRS)

Evans, Steven W.; Williamsen, Joel

2006-01-01

Taking the damage results from a previous paper as a guide, and using a tile model created for the STS-107 accident investigation, we used the SPHC hydrodynamic code to evaluate the probable worst-case impact effects of flat, rectangular, "flake-shaped," orbital debris particles on Space Shuttle thermal tiles. We compared the damage from flakes with that produced by spheres. The flakes and spheres were sized according to a "characteristic length" (Lc) derived from radar cross-section measurements, and embodied in the NASA Standard Breakup Model (SBM). Impacts were simulated at near-normal obliquity, at 12 km/sec. We modeled the worst-case flake orientation: a corner-on impact, an orientation we term a "Face A-B" impact. Results of our simulations indicate that flake impactors are less damaging than spheres of the same Lc. Since spherical impactors have been assumed in analyses of shuttle orbital debris impact risk, we find that these risks may have been overestimated. This work represents a preliminary second step, i.e., a follow-on to [1], in developing a sensitivity analysis for the expected range of effects on damage considering spherical vs. non-spherical impactors, as recommended by the Institute for Defense Analyses (IDA) report to the Columbia Accident Investigation Board.

Size distribution of particle-phase molecular markers during a severe winter pollution episode.

PubMed

Kleeman, Michael J; Riddle, Sarah G; Jakober, Chris A

2008-09-01

Airborne particulate matter was collected using filter samplers and cascade impactors in six size fractions below 1.8 microm during a severe winter air pollution event at three sites in the Central Valley of California. The smallest size fraction analyzed was 0.056 < Dp <0.1 microm particle diameter, which accounts for the majority of the mass in the ultrafine (PM0.1) size range. Separate samples were collected during the daytime (10 a.m. to 6 p.m. PST) and nighttime (8 p.m. to 8 a.m. PST) to characterize diurnal patterns. Each sample was extracted with organic solvents and analyzed using gas chromatography mass spectrometry for molecular markers that can be used for size-resolved source apportionment calculations. Colocated impactor and filter measurements were highly correlated (R8 > 0.8) for retene, benzo[ghi]flouranthene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[e]pyrene, benzo[a]pyrene, perylene, indeno[1,2,3-cd]pyrene, benzo[ghi]perylene, coronene, MW302 polycyclic aromatic hydrocarbon (PAHs), 17beta(H)-21alpha(H)-30-norhopane, 17alpha(H)-21beta(H)-hopane, alphabetabeta-20R-C29-ethylcholestane, levoglucosan, and cholesterol. Of these compounds, levoglucosan was present in the highest concentration (60-2080 ng m(-3)) followed by cholesterol (6-35 ng m(-3)), PAHs (2-38 ng m(-3)), and hopanes and steranes (0-2 ng m(-3)). Nighttime concentrations were higher than daytime concentrations in all cases. Organic compound size distributions were generally similar to the total carbon size distributions during the nighttime but showed greater variability during the daytime. This may reflect the dominance of fresh emission in the stagnant surface layer during the evening hours and the presence of aged organic aerosol at the surface during the daytime when the atmosphere is better mixed. All of the measured organic compound particle size distributions had a single mode that peaked somewhere between 0.18 and 0.56 microm, but the width of each distribution varied by compound. Cholesterol generally had the broadest particle size distribution, while benzo[ghi]perylene and 17alpha(H)-21beta(H)-29-norhopane generally had sharper peaks. The difference between the size distributions of the various particle-phase organic compounds reflects the fact that these compounds exist in particles emitted from different sources. The results of the current study will prove useful for size-resolved source apportionment exercises.

Titan impacts and escape

NASA Astrophysics Data System (ADS)

Korycansky, D. G.; Zahnle, Kevin J.

2011-01-01

We report on hydrodynamic calculations of impacts of large (multi-kilometer) objects on Saturn's moon Titan. We assess escape from Titan, and evaluate the hypothesis that escaping ejecta blackened the leading hemisphere of Iapetus and peppered the surface of Hyperion. We carried out two- and three-dimensional simulations of impactors ranging in size from 4 to 100 km diameter, impact velocities between 7 and 15 km s -1, and impact angles from 0° to 75° from the vertical. We used the ZEUSMP2 hydrocode for the calculations. Simulations were made using three different geometries: three-dimensional Cartesian, two-dimensional axisymmetric spherical polar, and two-dimensional plane polar. Three-dimensional Cartesian geometry calculations were carried out over a limited domain (e.g. 240 km on a side for an impactor of size di = 10 km), and the results compared to ones with the same parameters done by Artemieva and Lunine (2005); in general the comparison was good. Being computationally less demanding, two-dimensional calculations were possible for much larger domains, covering global regions of the satellite (from 800 km below Titan's surface to the exobase altitude 1700 km above the surface). Axisymmetric spherical polar calculations were carried out for vertical impacts. Two-dimensional plane-polar geometry calculations were made for both vertical and oblique impacts. In general, calculations among all three geometries gave consistent results. Our basic result is that the amount of escaping material is less than or approximately equal to the impactor mass even for the most favorable cases. Amounts of escaping material scaled most strongly as a function of velocity, with high-velocity impacts generating the largest amount, as expected. Dependence of the relative amount of escaping mass fesc = mesc/ Mi on impactor diameter di was weak. Oblique impacts (impact angle θi > 45°) were more effective than vertical or near-vertical impacts; ratios of mesc/ Mi ˜ 1-2 were found in the simulations.

On the origin of the organic-rich material on Ceres

NASA Astrophysics Data System (ADS)

Marchi, Simone; Bowling, Timothy; De Sanctis, Maria Cristina

2017-10-01

The detection of localized, organic-rich material on Ceres [1] poses an interesting conundrum. Either the organic-rich material has an exogenous origin, and thus it has been delivered to Ceres after its formation; or it has an endogenous origin, and thus it has been synthesized and/or concentrated in a specific location on Ceres via internal processes.Both scenarios have shortfalls, indicating we may ultimately be missing how organic matter has been formed, transported and reworked in solar system objects. The very location of Ceres at the boundary between the inner and outer solar system, and its intriguing composition characterized by clays, sodium- and ammonium-carbonates [2], suggest Ceres experienced a very complex chemical evolution. The role of organics in this evolution is not fully understood, with important astrobiological implications [3].Here we investigate the viability of organics delivery to Ceres via asteroidal/cometary impactors. We will present iSALE shock physics code [4-5] simulations that explore a range of impact parameters, such as impactor sizes and velocities, and discuss the likelihood of organics delivery. We find that comet-like projectiles, with relatively high impact velocities, are expected to lose almost all of their organics due to shock compression. Asteroidal-like impactors, with lower incident velocities, can retain 20-30% of their pre-impact organic material during delivery, especially for small impactors and very oblique impact angles. However, the spatial distribution of organics on Ceres seems difficult to reconcile with delivery from small main belt asteroids. These findings corroborate an endogenous origin for the organics on Ceres.[1] De Sanctis M. C. et al. Science 355, 2016. [2] De Sanctis M. C. et al. Nature 536, 2016. [3] Castillo-Rogez J. C. et al. Planetary Science Vision 2050 Workshop 2017 (LPI Contrib. No. 1989). [4] Amsden A. et al. LANL Report, LA-8095, 1980. [5] Collins G. S. et al. MAPS 39, 2004.

A 500-kiloton airburst over Chelyabinsk and an enhanced hazard from small impactors

NASA Astrophysics Data System (ADS)

Brown, P. G.; Assink, J. D.; Astiz, L.; Blaauw, R.; Boslough, M. B.; Borovička, J.; Brachet, N.; Brown, D.; Campbell-Brown, M.; Ceranna, L.; Cooke, W.; de Groot-Hedlin, C.; Drob, D. P.; Edwards, W.; Evers, L. G.; Garces, M.; Gill, J.; Hedlin, M.; Kingery, A.; Laske, G.; Le Pichon, A.; Mialle, P.; Moser, D. E.; Saffer, A.; Silber, E.; Smets, P.; Spalding, R. E.; Spurný, P.; Tagliaferri, E.; Uren, D.; Weryk, R. J.; Whitaker, R.; Krzeminski, Z.

2013-11-01

Most large (over a kilometre in diameter) near-Earth asteroids are now known, but recognition that airbursts (or fireballs resulting from nuclear-weapon-sized detonations of meteoroids in the atmosphere) have the potential to do greater damage than previously thought has shifted an increasing portion of the residual impact risk (the risk of impact from an unknown object) to smaller objects. Above the threshold size of impactor at which the atmosphere absorbs sufficient energy to prevent a ground impact, most of the damage is thought to be caused by the airburst shock wave, but owing to lack of observations this is uncertain. Here we report an analysis of the damage from the airburst of an asteroid about 19 metres (17 to 20 metres) in diameter southeast of Chelyabinsk, Russia, on 15 February 2013, estimated to have an energy equivalent of approximately 500 (+/-100) kilotons of trinitrotoluene (TNT, where 1 kiloton of TNT = 4.185×1012 joules). We show that a widely referenced technique of estimating airburst damage does not reproduce the observations, and that the mathematical relations based on the effects of nuclear weapons--almost always used with this technique--overestimate blast damage. This suggests that earlier damage estimates near the threshold impactor size are too high. We performed a global survey of airbursts of a kiloton or more (including Chelyabinsk), and find that the number of impactors with diameters of tens of metres may be an order of magnitude higher than estimates based on other techniques. This suggests a non-equilibrium (if the population were in a long-term collisional steady state the size-frequency distribution would either follow a single power law or there must be a size-dependent bias in other surveys) in the near-Earth asteroid population for objects 10 to 50 metres in diameter, and shifts more of the residual impact risk to these sizes.

Mass Transfer via Low-Velocity Rebound in a Microgravity Environment

NASA Astrophysics Data System (ADS)

Jarmak, S. G.; Colwell, J. E.; Brisset, J.; Dove, A.; Brown, A. Q.

2017-12-01

Observations of low-velocity collisions (< 1 m/s) between μm to cm-size particles in a microgravity environment are crucial to an understanding of the surface properties of small, airless bodies as well as the processes that lead to their formation. The COLLIDE (Collisions Into Dust Experiment) and PRIME (Physics of Regolith Impacts in Microgravity Experiment) programs created impacts into simulated planetary regolith with cm-scale impactors to observe ejecta production and coefficients of restitution in microgravity. These experiments were carried out on orbit (COLLIDE, COLLIDE-2), in suborbital space (COLLIDE-3), and on parabolic airplane flights (PRIME) under vacuum. Some impacts at speeds less than 40 cm/s resulted in mass transfer from the target regolith onto the impactor. To study these mass-transfer collisions in more detail without the cost or time requirements of spaceflight or parabolic flights, we developed an experimental apparatus in a laboratory drop tower (free-fall time 0.75 s) and performed experiments at standard pressure. The impactor is suspended from a spring and remains in contact with the bed of regolith until free-fall allows the spring to retract and pull the impactor upwards. This method allowed us to simulate the rebound portion of a low-velocity collision in a laboratory microgravity environment. We achieved rebound velocities of 10 - 60 cm/s, and we observed mass transfer events with rebound speeds below 40 cm/s. The amount of mass transfer produced was more significant than a monolayer of granular material, but less than the amount observed in the COLLIDE and PRIME experiments. These mass-transfer collisions may play a role in the growth of planetesimals. We will present the results of our laboratory-based studies where we vary impact velocity and target material, and discuss implications for collisional evolution in the protoplanetary disk and planetary rings.

The Deflection Question

NASA Astrophysics Data System (ADS)

Greenberg, A. H.; Nesvold, E.; van Heerden, E.; Erasmus, N.; Marchis, F.

2016-12-01

On 15 February, 2013, a 15 m diameter asteroid entered the Earth's atmosphere over Russia. The resulting shockwave injured nearly 1500 people, and incurred 33 million (USD) in infrastructure damages. The Chelyabinsk meteor served as a forceful demonstration of the threat posed to Earth by the hundreds of potentially hazardous objects (PHOs) that pass near the Earth every year. Although no objects have yet been discovered on an impact course for Earth, an impact is virtually statistically guaranteed at some point in the future. While many impactor deflection technologies have been proposed, humanity has yet to demonstrate the ability to divert an impactor when one is found. Developing and testing any single proposed technology will require significant research time and funding. This leaves open an obvious question - towards which technologies should funding and research be directed, in order to maximize our preparedness for when an impactor is eventually found? To help answer this question, we have created a detailed framework for analyzing various deflection technologies and their effectiveness. Using an n-body integrator (REBOUND), we have simulated the attempted deflections of a population of Earth-impacting objects with a variety of velocity perturbations (∂Vs), and measured the effects that these perturbations had on impact probability. We then mapped the ∂Vs applied in the orbital simulations to the technologies capable of achieving those perturbations, and analyzed which set of technologies would be most effective at preventing a PHO from impacting the earth. As a final step, we used the results of these simulations to train a machine learning algorithm. This algorithm, combined with a simulated PHO population, can predict which technologies are most likely to be needed. The algorithm can also reveal which impactor observables (mass, spin, orbit, etc.) have the greatest effect on the choice of deflection technology. These results can be used as a tool to inform funding decisions for both deflection technology development and PHO characterization missions.

The Deflector Selector: A Machine Learning Framework for Prioritizing Deflection Technology Development

NASA Astrophysics Data System (ADS)

Van Heerden, Elmarie; Erasmus, Nicolas; Greenberg, Adam; Nesvold, Erika; Galache, Jose Luis; Dahlstrom, Eric; Marchis, Franck

2016-10-01

On 15 February, 2013, a ~15 m diameter asteroid entered the Earth's atmosphere over Russia. The resulting shockwave injured nearly 1500 people, and incurred ~33 million (USD) in infrastructure damages. The Chelyabinsk meteor served as a forceful demonstration of the threat posed to Earth by the hundreds of potentially hazardous objects (PHOs) that pass near the Earth every year. Although no objects have yet been discovered on an impact course for Earth, an impact is virtually statistically guaranteed at some point in the future. While many impactor deflection technologies have been proposed, humanity has yet to demonstrate the ability to divert an impactor when one is found. Developing and testing any single proposed technology will require significant research time and funding. This leaves open an obvious question - towards which technologies should funding and research be directed, in order to maximize our preparedness for when an impactor is eventually found?To help answer this question, we have created a detailed framework for analyzing various deflection technologies and their effectiveness. Using an n-body integrator (REBOUND), we have simulated the attempted deflections of a population of Earth-impacting objects with a variety of velocity perturbations (∂Vs), and measured the effects that these perturbations had on impact probability. We then mapped the ∂Vs applied in the orbital simulations to the technologies capable of achieving those perturbations, and analyzed which set of technologies would be most effective at preventing a PHO from impacting the earth. As a final step, we used the results of these simulations to train a machine learning algorithm. This algorithm, combined with a simulated PHO population, can predict which technologies are most likely to be needed. The algorithm can also reveal which impactor observables (mass, spin, orbit, etc.) have the greatest effect on the choice of deflection technology. These results can be used as a tool to inform funding decisions for both deflection technology development and PHO characterization missions.

Rubble-pile Simulations Using The Open Dynamics Engine

NASA Astrophysics Data System (ADS)

Korycansky, Donald; Asphaug, E.

2008-09-01

We describe a series of calculations of low-speed collisions of km-scale rubble piles (i.e. asteroids or planetesimals), similar to previous work (Korycansky and Asphaug 2006). The rubble piles are aggregates of polyhedra held together by gravity and friction. Collision velocities are typically of order 1 to 100 m/sec.In this work we make use of a so-called "physics engine" to solve the equations of rigid-body motion and collisions of the polyhedra. Such code libraries have been primarily developed for computer simulations and games. The chief advantage of these libraries is the inclusion of sophisticated algorithms for collision detection, which we have found to be the main computational bottleneck in our calculations. The package we have used is the Open Dynamics Engine, a freely available open-source library (www.ode.org). It solves the equations of motion to first-order accuracy in time and utilizes a fast algorithm for collision detection. We have found a factor of approximately 30 speed-up for our calculations, allowing the exploration of a much larger range of parameter space and the running of multiple calculations in order to sample the stochasticity of the results. For the calculations we report on here, the basic model is the collision of an impactor in the range 0.1--1 km in diameter with a target of 1 km diameter.argets are modeled with 1000 polyhedral elements and impactors modeled with 1 to 1000 elements depending on mass. Collisions of objects with both equal-mass elements, and elements chosen from a power-law distribution, are studied. We concentrate on determining the energy required for catastrophic disruption (Q*D) as a function of impactor/target mass atio and impactor parameter for off-center collisions. This work has been supported by NASA Planetary Geology and Geophysics Program grant NNX07AQ04G.

Europa's small impactor flux and seismic detection predictions

NASA Astrophysics Data System (ADS)

Tsuji, Daisuke; Teanby, Nicholas A.

2016-10-01

Europa is an attractive target for future lander missions due to its dynamic surface and potentially habitable sub-surface environment. Seismology has the potential to provide powerful new constraints on the internal structure using natural sources such as faults or meteorite impacts. Here we predict how many meteorite impacts are likely to be detected using a single seismic station on Europa to inform future mission planning efforts. To this end, we derive: (1) the current small impactor flux on Europa from Jupiter impact rate observations and models; (2) a crater diameter versus impactor energy scaling relation for icy moons by merging previous experiments and simulations; and (3) scaling relations for seismic signal amplitudes as a function of distance from the impact site for a given crater size, based on analogue explosive data obtained on Earth's ice sheets. Finally, seismic amplitudes are compared to predicted noise levels and seismometer performance to determine detection rates. We predict detection of 0.002-20 small local impacts per year based on P-waves travelling directly through the ice crust. Larger regional and global-scale impact events, detected through mantle-refracted waves, are predicted to be extremely rare (10-8-1 detections per year), so are unlikely to be detected by a short duration mission. Estimated ranges include uncertainties from internal seismic attenuation, impactor flux, and seismic amplitude scaling. Internal attenuation is the most significant unknown and produces extreme uncertainties in the mantle-refracted P-wave amplitudes. Our nominal best-guess attenuation model predicts 0.002-5 local direct P detections and 6 × 10-6-0.2 mantle-refracted detections per year. Given that a plausible Europa landed mission will only last around 30 days, we conclude that impacts should not be relied upon for a seismic exploration of Europa. For future seismic exploration, faulting due to stresses in the rigid outer ice shell is likely to be a much more viable mechanism for probing Europa's interior.

Impact-induced melting and heating of planetary interiors - implications for the thermo-chemical evolution of planets and crystallization of magma oceans

NASA Astrophysics Data System (ADS)

Wuennemann, K.; Manske, L.; Zhu, M.; Nakajima, M.; Breuer, D.; Schwinger, S.; Plesa, A. C.

2017-12-01

Large collisions and giant impact events play an important role in the thermo-chemical evolution of planets during their early and late accretion phases. Besides material that is delivered by differentiated and primitive projectiles a significant amount of the kinetic impact energy is transferred to the planets interior resulting in heating and widespread melting of matter. As a consequence, giant impacts are thought to form global magma oceans. The amount and distribution of impact-induced heating and melting has been previously estimated by scaling laws derived from small-scale impact simulations and experiments, simple theoretical considerations, and observations at terrestrial craters. We carried out a suite of numerical models using the iSALE shock physics code and an SPH code combined with the ANEOS package to investigate the melt production in giant impacts and planetary collision events as a function of impactor size and velocity, and the target temperature. Our results are consistent with previously derived scaling laws only for smaller impactors (<10 km in diameter), but significantly deviate for larger impactors: (1) for hot planets, where the temperature below the lithosphere lies close to the solidus temperature, the melt production is significantly increased for impactors comparable in the size to the depth of the lithosphere. The resulting crater structures would drown in their own melt and only large igneous provinces (local magma oceans) would remain visible at the surface;(2) even bigger impacts (planetary collisions) generate global magma oceans; (3) impacts into a completely solidified (cold) target result in more localized heating in comparison to impacts into a magma ocean, where the impact-induced heating is distributed over a larger volume. In addition, we investigate the influence of impacts on a cooling and crystallization of magma oceans and use the lunar magma ocean as an example.

Design and characterization of emulsified spray dried alginate microparticles as a carrier for the dually acting drug roflumilast.

PubMed

Mahmoud, Azza A; Elkasabgy, Nermeen A; Abdelkhalek, Abdel Fatah A

2018-06-18

Roflumilast is a selective inhibitor of phosphodiesterase-4 isoenzyme in lung cells. Having psychiatric adverse reactions when administered orally affects negatively the patients' adherence to the drug. This work aimed to prepare emulsified spray dried alginate microparticles for the pulmonary delivery of roflumilast. Sodium alginate was used as microparticle-forming material, isopropyl myristate as an oil, Tween®80 as surfactant and calcium beta-glycerophosphate as cross-linking agent to enhance the mechanical properties of the particles. The prepared particles were evaluated for their encapsulation efficiency, particle size and in-vitro release. From the studied carriers, beta-cyclodextrin (CD) was the best regarding giving formulation smaller particle size and more sustained drug release. The inhalation profile of CD-based microparticles was investigated using Anderson cascade impactor. The aerosolization profile of CD-based microparticles suggested their efficiency to deliver the drug deep in the lung. The CD-based microparticles possessed more inhibitory effects on the viability of A549 cells and on the pro-inflammatory cytokines (TNF-α, IL-6 and IL-10) compared to the pure drug. Hence, CD-based microparticles could regulate the tumorigenesis besides tumor-associated inflammation. Finally, CD-based microparticles showed more sustained bronchodilatation properties in healthy human volunteers when compared to Ventolin®HFA. CD-based microparticles proved to be a promising carrier for inhaled roflumilast in human. Copyright © 2018. Published by Elsevier B.V.

Characterisation and seasonal variations of particles in the atmosphere of rural, urban and industrial areas: Organic compounds.

PubMed

Cazier, Fabrice; Genevray, Paul; Dewaele, Dorothée; Nouali, Habiba; Verdin, Anthony; Ledoux, Frédéric; Hachimi, Adam; Courcot, Lucie; Billet, Sylvain; Bouhsina, Saâd; Shirali, Pirouz; Garçon, Guillaume; Courcot, Dominique

2016-06-01

Atmospheric aerosol samples (PM2.5-0.3, i.e., atmospheric particles ranging from 0.3 to 2.5μm) were collected during two periods: spring-summer 2008 and autumn-winter 2008-2009, using high volume samplers equipped with cascade impactors. Two sites located in the Northern France were compared in this study: a highly industrialised city (Dunkirk) and a rural site (Rubrouck). Physicochemical analysis of particulate matter (PM) was undertaken to propose parameters that could be used to distinguish the various sources and to exhibit seasonal variations but also to provide knowledge of chemical element composition for the interpretation of future toxicological studies. The study showed that PM2.5-0.3 concentration in the atmosphere of the rural area remains stable along the year and was significantly lower than in the urban or industrial ones, for which concentrations increase during winter. High concentrations of polycyclic aromatic hydrocarbons (PAHs), dioxins, furans and dioxin like polychlorinated biphenyls (DL-PCBs), generated by industrial activities, traffic and municipal wastes incineration were detected in the samples. Specific criteria like Carbon Preference Index (CPI) and Combustion PAHs/Total PAHs ratio (CPAHs/TPAHs) were used to identify the possible sources of atmospheric pollution. They revealed that paraffins are mainly emitted by biogenic sources in spring-summer whereas as in the case of PAHs, they have numerous anthropogenic emission sources in autumn-winter (mainly from traffic and domestic heating). Copyright © 2016. Published by Elsevier B.V.

[Appropriate dust control measures for jade carving operations].

PubMed

Liu, Jiang; Wang, Qiushui; Liu, Guangquan

2002-12-01

To provide the appropriate dust control measures for jade carving operations. Dust concentrations in the workplace were measured according to GB/T 5748-85. Ventilation system of dust control were measured according to GB/T 16157-1996. Dust particle size distributions for different sources and particle size fraction collecting efficiencies of the dust collectors were measured with WY-1 in-stack 7 stage cascade impactors. On the basis of adopting wet process in the carving operations, local exhaust ventilation system for dust control was installed, which included: the special designed slot exhaust hoods with hood face velocity of 2.5 m/s and exhaust volume of 600 m3/h. The pipe sizes were determined according to the air volume passing through the pipe and the reasonable air velocities. Impinging scrubber or bag filter dust collector were selected to treat the dust laden air from the local exhaust ventilation system, which gave a total collecting efficiency of 97% for impinging scrubber and 98% for bag filter; The type of fan and its size were selected according to the total air volume of the ventilation system and maximum total pressure needed for the longest pipe line plus the pressure drop of the dust collector. Practical application showed that, after installation and use of the appropriate dust control measures, the dust concentrations in the workplaces could meet or nearly meet the national hygienic standard and the dust laden air at the local exhaust ventilation system could meet the national emission standard.

Particle size distribution of radioactive aerosols after the Fukushima and the Chernobyl accidents.

PubMed

Malá, Helena; Rulík, Petr; Bečková, Vera; Mihalík, Ján; Slezáková, Miriam

2013-12-01

Following the Fukushima accident, a series of aerosol samples were taken between 24th March and 13th April 2011 by cascade impactors in the Czech Republic to obtain the size distribution of (131)I, (134)Cs, (137)Cs, and (7)Be aerosols. All distributions could be considered monomodal. The arithmetic means of the activity median aerodynamic diameters (AMADs) for artificial radionuclides and for (7)Be were 0.43 and 0.41 μm with GDSs 3.6 and 3.0, respectively. The time course of the AMADs of (134)Cs, (137)Cs and (7)Be in the sampled period showed a slight decrease at a significance level of 0.05, whereas the AMAD pertaining to (131)I increased at a significance level of 0.1. Results obtained after the Fukushima accident were compared with results obtained after the Chernobyl accident. The radionuclides released during the Chernobyl accident for which we determined the AMAD fell into two categories: refractory radionuclides ((140)Ba, (140)La (141)Ce, (144)Ce, (95)Zr and (95)Nb) and volatile radionuclides ((134)Cs, (137)Cs, (103)Ru, (106)Ru, (131)I, and (132)Te). The AMAD of the refractory radionuclides was approximately 3 times higher than the AMAD of the volatile radionuclides; nevertheless, the size distributions for volatile radionuclides having a mean AMAD value of 0.51 μm were very close to the distributions after the Fukushima accident. Copyright © 2013 Elsevier Ltd. All rights reserved.

Feasibility of haloperidol-anchored albumin nanoparticles loaded with doxorubicin as dry powder inhaler for pulmonary delivery.

PubMed

Varshosaz, Jaleh; Hassanzadeh, Farshid; Mardani, Amin; Rostami, Mahboubeh

2015-03-01

Haloperidol (Hal) is a ligand that can target sigma 2 receptors over-expressed in non-small cell lung cancer. Hal targeted nanoparticles of bovine serum albumin (BSA) were prepared for pulmonary delivery of doxorubicin (DOX). The conjugation was confirmed by Fourier transform infrared spectroscopy (FTIR) and (1)H nuclear magnetic resonance ((1)H NMR) spectroscopic methods. Nanoparticles were prepared by desolvation method from BSA-Hal and were loaded with DOX. They were characterized for their morphology, particle size, zeta potential, drug loading and release efficiency. The optimized nanoparticles were spray-dried using trehalose, l-leucin and mannitol as dry powder inhaler (DPI) in different inlet temperatures between 80 and 120°C. The obtained nanocomposites were characterized for their aerodynamic diameter, specific surface area (cm(2)/g) and fine particle fraction (FPF) by a Cascade Impactor device. The optimized nanoparticles showed particle size of 218 nm, zeta potential of -25.4 mV, drug entrapment efficiency of 89% and release efficiency of 56% until 2 h. After spray drying of these nanoparticles, the best results were obtained from mannitol with an inlet temperature of 80°C which produced a mean aerodynamic diameter of 4.58 μm, FPF of 66% and specific surface area of 6302.99 cm(2)/g. The obtained results suggest that the designed DPI could be a suitable inhaler for targeted delivery of DOX in pulmonary delivery.

Seasonality in airborne bacterial, fungal, and (1→3)-β-D-glucan concentrations in two indoor laboratory animal rooms.

PubMed

Hwang, Sungho; Ko, Yeji; Park, Donguk; Yoon, Chungsik

2018-01-01

The purpose of this study was to assess the temporal changes in the concentrations of bioaerosols in a laboratory mouse room (LMR) and laboratory rabbit room (LRR), and to determine environmental factors associated with the culturable bacteria, fungi and (1→3)-β-D-glucan concentrations. The concentrations of culturable airborne bacteria, fungi and (1→3)-β-D-glucan in the LMR and LRR were sampled once a month from March 2011 to February 2012. A single-stage viable cascade impactor was used to sample bacteria and fungi, while a two-stage cyclone bioaerosol sampler was used to collect airborne (1→3)-β-D-glucan. The culturable bacterial concentrations in the LMR showed a gradual increase during the summer. The culturable fungal concentrations showed similar seasonal patterns of change in the LMR and LRR with a noticeable increase during the summer. The (1→3)-β-D-glucan concentrations were highest during the warmer spring and summer months. Relative humidity (RH) was the environmental factor most associated with the concentrations of culturable bacteria and fungi. The overall airborne microbe concentrations were significantly higher in the LRR than in the LMR. Airborne microbe concentrations in the LMR and LRR varied greatly depending on season, and these changes were affected by environmental factors. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

In vitro inflammatory and cytotoxic effects of size-segregated particulate samples collected during long-range transport of wildfire smoke to Helsinki.

PubMed

Jalava, Pasi I; Salonen, Raimo O; Hälinen, Arja I; Penttinen, Piia; Pennanen, Arto S; Sillanpää, Markus; Sandell, Erik; Hillamo, Risto; Hirvonen, Maija-Riitta

2006-09-15

The impact of long-range transport (LRT) episodes of wildfire smoke on the inflammogenic and cytotoxic activity of urban air particles was investigated in the mouse RAW 264.7 macrophages. The particles were sampled in four size ranges using a modified Harvard high-volume cascade impactor, and the samples were chemically characterized for identification of different emission sources. The particulate mass concentration in the accumulation size range (PM(1-0.2)) was highly increased during two LRT episodes, but the contents of total and genotoxic polycyclic aromatic hydrocarbons (PAH) in collected particulate samples were only 10-25% of those in the seasonal average sample. The ability of coarse (PM(10-2.5)), intermodal size range (PM(2.5-1)), PM(1-0.2) and ultrafine (PM(0.2)) particles to cause cytokine production (TNFalpha, IL-6, MIP-2) reduced along with smaller particle size, but the size range had a much smaller impact on induced nitric oxide (NO) production and cytotoxicity or apoptosis. The aerosol particles collected during LRT episodes had a substantially lower activity in cytokine production than the corresponding particles of the seasonal average period, which is suggested to be due to chemical transformation of the organic fraction during aging. However, the episode events were associated with enhanced inflammogenic and cytotoxic activities per inhaled cubic meter of air due to the greatly increased particulate mass concentration in the accumulation size range, which may have public health implications.

Effect of pH and leucine concentration on aerosolization properties of carrier-free formulations of levofloxacin.

PubMed

Barazesh, Ahmadreza; Gilani, Kambiz; Rouini, Mohammadreza; Barghi, Mohammad Ali

2018-06-15

The aim of this study was to evaluate the effect of leucine at different pH values preferred for inhalation on particle characteristics and aerosolization performance of spray dried carrier-free formulations of levofloxacin. A full factorial design was applied to optimize the formulation containing levofloxacin with or without leucine in different pH values and the optimum condition was determined. Particle size and morphology, crystallinity state, electrostatic charge and surface composition of the particles were determined. Aerodynamic properties of the powders were also assessed by an Andersen cascade impactor after aerosolization through an Aerolizer® at an air flow rate of 60 L/min. The pH of initial solution affected various physical properties of the drug containing particles and hence their in vitro deposition. The profound effect of pH was on water content, electrostatic charge and surface composition of the particles. The negative effect of water content on in vitro deposition of the drug was covered by preferred surface accumulation of leucine at pH 6. Optimum formulation which obtained by co-spray drying of the drug with 21.79% leucine at pH 5.98 presented a fine particle fraction equal to 54.38. In conclusion, changing pH of the initial solution influenced the effect of leucine on aerosolization of levofloxacine spray dried particles by modification of their physical properties. Copyright © 2018 Elsevier B.V. All rights reserved.

Polonium in size fractionated mainstream cigarette smoke, predicted deposition and associated internal radiation dose.

PubMed

Tiwari, M; Sahu, S K; Bhangare, R C; Pandit, G G

2016-10-01

In this study, size fractionated mass and 210 Po activity concentrations in mainstream cigarette smoke (MCS) were monitored for three popular cigarette brands. Size segregated collection of MCS was carried out using a cascade type impactor, while mass and 210 Po activity concentration were analyzed gravimetrically and alpha spectrometry (following the radiochemical separation) respectively. Multiple-Path Particle Dosimetry (MPPD V2.11) model is used for prediction of deposition fraction calculations for the MCS deposition in different compartment of human respiratory tract. The activity concentration of 210 Po is founds 10.56 ± 2.46 mBq per cigarette for the tested cigarette brands. 210 Po size distribution indicates most of this associates with fine fraction (Dp < 2.23 μm) of cigarette smoke. The committed annual effective dose to smokers (smoking on an average 20 cigarette a day), considering the 210 Po and 210 Pb concentrations (assuming it is in secular equilibrium with 210 Po) in MCS, was estimated between 0.22 and 0.40 mSv, with mean value of 0.30 mSv for tested cigarette brands. Considering the risk factor of fatal cancer due to radiation exposure of lung (exposure time of 30 years); the average collective estimated fatal cancer risk is estimated as 1.5 × 10 -4 due to 210 Po and 210 Pb exposure to smokers. Copyright © 2016. Published by Elsevier Ltd.

Pesticides in the atmosphere: a comparison of gas-particle partitioning and particle size distribution of legacy and current-use pesticides

NASA Astrophysics Data System (ADS)

Degrendele, C.; Okonski, K.; Melymuk, L.; Landlová, L.; Kukučka, P.; Audy, O.; Kohoutek, J.; Čupr, P.; Klánová, J.

2015-09-01

This study presents a comparison of seasonal variation, gas-particle partitioning and particle-phase size distribution of organochlorine pesticides (OCPs) and current-use pesticides (CUPs) in air. Two years (2012/2013) of weekly air samples were collected at a background site in the Czech Republic using a high-volume air sampler. To study the particle-phase size distribution, air samples were also collected at an urban and rural site in the area of Brno, Czech Republic, using a cascade impactor separating atmospheric particulates according to six size fractions. The timing and frequencies of detection of CUPs related to their legal status, usage amounts and their environmental persistence, while OCPs were consistently detected throughout the year. Two different seasonal trends were noted: certain compounds had higher concentrations only during the growing season (April-September) and other compounds showed two peaks, first in the growing season and second in plowing season (October-November). In general, gas-particle partitioning of pesticides was governed by physicochemical properties, with higher vapor pressure leading to higher gas phase fractions, and associated seasonality in gas-particle partitioning was observed in nine pesticides. However, some anomalous partitioning was observed for fenpropimorph and chlorpyrifos suggesting the influence of current pesticide application on gas-particle distributions. Nine pesticides had highest particle phase concentrations on fine particles (< 0.95 μm) and four pesticides on coarser (> 1.5 μm) particles.

Engineered sodium hyaluronate respirable dry powders for pulmonary drug delivery.

PubMed

Martinelli, Francesco; Balducci, Anna Giulia; Kumar, Abhinav; Sonvico, Fabio; Forbes, Ben; Bettini, Ruggero; Buttini, Francesca

2017-01-30

Sodium hyaluronate (HYA) warrants attention as a material for inhalation due to its (i) therapeutic potential, (ii) utility as a formulation excipient or drug carrier, and (iii) ability to target lung inflammation and cancer. This study aimed to overcome formulation and manufacturing impediments to engineer biocompatible spray-dried HYA powders for inhalation. Novel methodology was developed to produce HYA microparticles by spray drying. Different types of surfactant were included in the formulation to improve powder respirability, which was evaluated in vitro using cascade impactors. The individual formulation components and formulated products were evaluated for their biocompatibility with A549 respiratory epithelial cells. The inclusion of stearyl surfactants, 5% w/v, produced the most respirable HYA-powders; FPF 59.0-66.3%. A trend to marginally higher respirability was observed for powders containing stearylamine>stearyl alcohol>cetostearyl alcohol. Pure HYA was biocompatible with A549 cells at all concentrations measured, but the biocompatibility of the stearyl surfactants (based on lethal concentration 50%; LC 50 ) in the MTT assay ranked stearyl alcohol>cetostearyl alcohol>stearylamine with LC 50 of 24.7, 13.2 and 1.8μg/mL, respectively. We report the first respirable HYA powders produced by spray-drying. A lead formulation containing 5% stearyl alcohol was identified for further studies aimed at translating the proposed benefits of inhaled HYA into safe and clinically effective HYA products. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

Damage Characteristics and Residual Strength of Composite Sandwich Panels Impacted with and Without Compression Loading

NASA Technical Reports Server (NTRS)

McGowan, David M.; Ambur, Damodar R.

1998-01-01

The results of an experimental study of the impact damage characteristics and residual strength of composite sandwich panels impacted with and without a compression loading are presented. Results of impact damage screening tests conducted to identify the impact-energy levels at which damage initiates and at which barely visible impact damage occurs in the impacted facesheet are discussed. Parametric effects studied in these tests include the impactor diameter, dropped-weight versus airgun-launched impactors, and the effect of the location of the impact site with respect to the panel boundaries. Residual strength results of panels tested in compression after impact are presented and compared with results of panels that are subjected to a compressive preload prior to being impacted.

Impact basins in Southern Daedalia, Mars: Evidence for clustered impactors?

NASA Technical Reports Server (NTRS)

Frey, Herbert; Roark, James H.

1994-01-01

The distribution of ancient massifs and old cratered terrain in the southern Daedalia region indicate the presence of at least two and probably three impact basins of large size. One of these is located near where Craddock et al. placed their center for the Daedalia Basin, but it has very different ring diameters. These basins have rings exceeding 1000 km diameter and overlap significantly with centers separated by 500 to 600 km at nearly identical latitudes of -26 to -29 deg. The smaller westernmost basin appears slightly better preserved, but there is little evidence for obvious superposition that might imply a temporal sequence. Recognizing the improbability of random impacts producing aligned, nearly contemporaneous features, we suggest these basins may have resulted from clustered impactors.

VKORC1 haplotypes are associated with arterial vascular diseases (stroke, coronary heart disease, and aortic dissection).

PubMed

Wang, Yibo; Zhang, Weili; Zhang, Yuhui; Yang, Yuejin; Sun, Lizhong; Hu, Shengshou; Chen, Jilin; Zhang, Channa; Zheng, Yi; Zhen, Yisong; Sun, Kai; Fu, Chunyan; Yang, Tao; Wang, Jianwei; Sun, Jing; Wu, Haiying; Glasgow, Wayne C; Hui, Rutai

2006-03-28

The haplotypes in the gene vitamin K epoxide reductase complex subunit 1 (VKORC1) have been found to affect warfarin dose response through effects on the formation of reduced-form vitamin K, a cofactor for gamma-carboxylation of vitamin K-dependent proteins, which is involved in the coagulation cascade and has a potential impact on atherosclerosis. We hypothesized that VKORC1-dependent effects on the coagulation cascade and atherosclerosis would contribute to susceptibility for vascular diseases. To test the hypothesis, we studied the association of polymorphisms of VKORC1 with stroke (1811 patients), coronary heart disease (740 patients), and aortic dissection (253 patients) compared with matched controls (n=1811, 740, and 416, respectively). Five common noncoding single-nucleotide polymorphisms of VKORC1 were identified in a natural haplotype block with strong linkage disequilibrium (D'>0.9, r2>0.9), then single-nucleotide polymorphism (SNP) +2255 in the block was selected for the association study. We found that the presence of the C allele of the +2255 locus conferred almost twice the risk of vascular disease (odds ratio [OR] 1.95, 95% confidence interval [CI] .58 to 2.41, P<0.001 for stroke; OR 1.72, 95% CI 1.24 to 2.38, P<0.01 for coronary heart disease; and OR 1.90, 95% CI 1.04 to 3.48, P<0.05 for aortic dissection). We also observed that subjects with the CC and CT genotypes had lower levels of undercarboxylated osteocalcin (a regulator for the bone), probably vascular calcification, and lower levels of protein induced in vitamin K absence or antagonism II (PIVKA-II, a des-gamma-carboxy prothrombin) than those with TT genotypes. The haplotype of VKORC1 may serve as a novel genetic marker for the risk of stroke, coronary heart disease, and aortic dissection.

SU-G-IeP4-12: Performance of In-111 Coincident Gamma-Ray Counting: A Monte Carlo Simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pahlka, R; Kappadath, S; Mawlawi, O

2016-06-15

Purpose: The decay of In-111 results in a non-isotropic gamma-ray cascade, which is normally imaged using a gamma camera. Creating images with a gamma camera using coincident gamma-rays from In-111 has not been previously studied. Our objective was to explore the feasibility of imaging this cascade as coincidence events and to determine the optimal timing resolution and source activity using Monte Carlo simulations. Methods: GEANT4 was used to simulate the decay of the In-111 nucleus and to model the gamma camera. Each photon emission was assigned a timestamp, and the time delay and angular separation for the second gamma-ray inmore » the cascade was consistent with the known intermediate state half-life of 85ns. The gamma-rays are transported through a model of a Siemens dual head Symbia “S” gamma camera with a 5/8-inch thick crystal and medium energy collimators. A true coincident event was defined as a single 171keV gamma-ray followed by a single 245keV gamma-ray within a specified time window (or vice versa). Several source activities (ranging from 10uCi to 5mCi) with and without incorporation of background counts were then simulated. Each simulation was analyzed using varying time windows to assess random events. The noise equivalent count rate (NECR) was computed based on the number of true and random counts for each combination of activity and time window. No scatter events were assumed since sources were simulated in air. Results: As expected, increasing the timing window increased the total number of observed coincidences albeit at the expense of true coincidences. A timing window range of 200–500ns maximizes the NECR at clinically-used source activities. The background rate did not significantly alter the maximum NECR. Conclusion: This work suggests coincident measurements of In-111 gamma-ray decay can be performed with commercial gamma cameras at clinically-relevant activities. Work is ongoing to assess useful clinical applications.« less

Craters in aluminum 1100 targets using glass projectiles at 1-7 km/s

NASA Technical Reports Server (NTRS)

Bernhard, R. P.; See, T. H.; Hoerz, F.; Cintala, M. J.

1994-01-01

We report on impact experiments using soda-lime glass spheres of 3.2 mm diameter and aluminum targets (1100 series). The purpose is to assist in the interpretation of LDEF instruments and in the development of future cosmic-dust collectors in low-Earth orbit. Because such instruments demand understanding of both the cratering and penetration process, we typically employ targets with thicknesses that range from massive, infinite half-space targets, to ultrathin films. This report addresses a subset of cratering experiments that were conducted to fine-tune our understanding of crater morphology as a function of impact velocity. Also, little empirical insight exists about the physical distribution and shock-metamorphism of the impactor residues as a function of encounter speed, despite their recognized significance in the analysis of space-exposed surfaces. Soda-lime glass spheres were chosen as a reasonable analog to extraterrestrial silicates, and aluminum 1100 was chosen for targets, which among the common Al-alloys, best represents the physical properties of high-purity aluminum. These materials complement existing impact studies that typically employed metallic impactors and less ductile Al-alloys. We have completed dimensional analyses of the resulting craters and are in the process of investigating the detailed distribution of the unmelted and melted impactor residues via SEM methods, as well as potential compositional modifications of the projectile melts via electron microprobe.

Effect of Abdominal Loading Location on Liver Motion: Experimental Assessment using Ultrafast Ultrasound Imaging and Simulation with a Human Body Model.

PubMed

Le Ruyet, Anicet; Berthet, Fabien; Rongiéras, Frédéric; Beillas, Philippe

2016-11-01

A protocol based on ultrafast ultrasound imaging was applied to study the in situ motion of the liver while the abdomen was subjected to compressive loading at 3 m/s by a hemispherical impactor or a seatbelt. The loading was applied to various locations between the lower abdomen and the mid thorax while feature points inside the liver were followed on the ultrasound movie (2000 frames per second). Based on tests performed on five post mortem human surrogates (including four tested in the current study), trends were found between the loading location and feature point trajectory parameters such as the initial angle of motion or the peak displacement in the direction of impact. The impactor tests were then simulated using the GHBMC M50 human body model that was globally scaled to the dimensions of each surrogate. Some of the experimental trends observed could be reproduced in the simulations (e.g. initial angle) while others differed more widely (e.g. final caudal motion). The causes for the discrepancies need to be further investigated. The liver strain energy density predicted by the model was also widely affected by the impact location. Experimental and simulation results both highlight the importance of the liver position with respect to the impactor when studying its response in situ.

Small-scale impacts as potential trigger for landslides on small Solar system bodies

NASA Astrophysics Data System (ADS)

Hofmann, Marc; Sierks, Holger; Blum, Jürgen

2017-07-01

We conducted a set of experiments to investigate whether millimetre-sized impactors impinging on a granular material at several m s-1 are able to trigger avalanches on small, atmosphereless planetary bodies. These experiments were carried out at the Zentrum für angewandte Raumfahrttechnologie und Mikrogravitation (ZARM) drop tower facility in Bremen, Germany to facilitate a reduced gravity environment. Additional data were gathered at Earth gravity levels in the laboratory. As sample materials we used a ground Howardites, Eucrites and Diogenites (HED) meteorite and the Johnson Space Center (JSC) Mars-1 Martian soil simulant. We found that this type of small-scale impact can trigger avalanches with a moderate probability, if the target material is tilted to an angle close to the angle of repose. We additionally simulated a small-scale impact using the discrete element method code esys-particle. These simulations show that energy transfer from impactor to the target material is most efficient at low- and moderate-impactor inclinations and the transferred energy is retained in particles close to the surface due to a rapid dissipation of energy in lower material layers driven by inelastic collisions. Through Monte Carlo simulations we estimate the time-scale on which small-scale impacts with the observed characteristics will trigger avalanches covering all steep slopes on the surface of a small planetary body to be of the order 105 yr.

Scientific Objectives of Small Carry-on Impactor (SCI) and Deployable Camera 3 Digital (DCAM3-D): Observation of an Ejecta Curtain and a Crater Formed on the Surface of Ryugu by an Artificial High-Velocity Impact

NASA Astrophysics Data System (ADS)

Arakawa, M.; Wada, K.; Saiki, T.; Kadono, T.; Takagi, Y.; Shirai, K.; Okamoto, C.; Yano, H.; Hayakawa, M.; Nakazawa, S.; Hirata, N.; Kobayashi, M.; Michel, P.; Jutzi, M.; Imamura, H.; Ogawa, K.; Sakatani, N.; Iijima, Y.; Honda, R.; Ishibashi, K.; Hayakawa, H.; Sawada, H.

2017-07-01

The Small Carry-on Impactor (SCI) equipped on Hayabusa2 was developed to produce an artificial impact crater on the primitive Near-Earth Asteroid (NEA) 162173 Ryugu (Ryugu) in order to explore the asteroid subsurface material unaffected by space weathering and thermal alteration by solar radiation. An exposed fresh surface by the impactor and/or the ejecta deposit excavated from the crater will be observed by remote sensing instruments, and a subsurface fresh sample of the asteroid will be collected there. The SCI impact experiment will be observed by a Deployable CAMera 3-D (DCAM3-D) at a distance of ˜1 km from the impact point, and the time evolution of the ejecta curtain will be observed by this camera to confirm the impact point on the asteroid surface. As a result of the observation of the ejecta curtain by DCAM3-D and the crater morphology by onboard cameras, the subsurface structure and the physical properties of the constituting materials will be derived from crater scaling laws. Moreover, the SCI experiment on Ryugu gives us a precious opportunity to clarify effects of microgravity on the cratering process and to validate numerical simulations and models of the cratering process.

Design and application of an inertial impactor in combination with an ATP bioluminescence detector for in situ rapid estimation of the efficacies of air controlling devices on removal of bioaerosols.

PubMed

Yoon, Ki Young; Park, Chul Woo; Byeon, Jeong Hoon; Hwang, Jungho

2010-03-01

We proposed a rapid method to estimate the efficacies of air controlling devices in situ using ATP bioluminescence in combination with an inertial impactor. The inertial impactor was designed to have 1 mum of cutoff diameter, and its performance was estimated analytically, numerically, and experimentally. The proposed method was characterized using Staphylococcus epidermidis, which was aerosolized with a nebulizer. The bioaerosol concentrations were estimated within 25 min using the proposed method without a culturing process, which requires several days for colony formation. A linear relationship was obtained between the results of the proposed ATP method (RLU/m(3)) and the conventional culture-based method (CFU/m(3)), with R(2) 0.9283. The proposed method was applied to estimate the concentration of indoor bioaerosols, which were identified as a mixture of various microbial species including bacteria, fungi, and actinomycetes, in an occupational indoor environment, controlled by mechanical ventilation and an air cleaner. Consequently, the proposed method showed a linearity with the culture-based method for indoor bioaerosols with R(2) 0.8189, even though various kinds of microorganisms existed in the indoor air. The proposed method may be effective in monitoring the changes of relative concentration of indoor bioaerosols and estimating the effectiveness of air control devices in indoor environments.

The cometary and asteroidal impactor flux at the earth

NASA Technical Reports Server (NTRS)

Weissman, Paul R.

1988-01-01

The cratering records on the Earth and the lunar maria provide upper limits on the total impactor flux at the Earth's orbit over the past 600 Myr and the past 3.3 Gyr, respectively. These limits can be compared with estimates of the expected cratering rate from observed comets and asteroids in Earth-crossing orbits, corrected for observational selection effects and incompleteness, and including expected temporal variations in the impactor flux. Both estimates can also be used to calculate the probability of large impacts which may result in biological extinction events on the Earth. The estimated cratering rate on the Earth for craters greater than 10 km-diameter, based on counted craters on dated surfaces is 2.2 + or - 1.1 x 10 to the minus 14th power km(-2) yr(-1) (Shoemaker et al., 1979). Using a revised mass distribution for cometary nuclei based on the results of the spacecraft flybys of Comet Halley in 1986, and other refinements in the estimate of the cometary flux in the terrestrial planets zone, it is now estimated that long-period comets account for 11 percent of the cratering on the Earth (scaled to the estimate above), and short-period comets account for 4 pct (Weissman, 1987). However, the greatest contribution is from large but infrequent, random cometary showers, accounting for 22 pct of the terrestrial cratering.

Oxygen isotopic evidence for accretion of Earth's water before a high-energy Moon-forming giant impact.

PubMed

Greenwood, Richard C; Barrat, Jean-Alix; Miller, Martin F; Anand, Mahesh; Dauphas, Nicolas; Franchi, Ian A; Sillard, Patrick; Starkey, Natalie A

2018-03-01

The Earth-Moon system likely formed as a result of a collision between two large planetary objects. Debate about their relative masses, the impact energy involved, and the extent of isotopic homogenization continues. We present the results of a high-precision oxygen isotope study of an extensive suite of lunar and terrestrial samples. We demonstrate that lunar rocks and terrestrial basalts show a 3 to 4 ppm (parts per million), statistically resolvable, difference in Δ 17 O. Taking aubrite meteorites as a candidate impactor material, we show that the giant impact scenario involved nearly complete mixing between the target and impactor. Alternatively, the degree of similarity between the Δ 17 O values of the impactor and the proto-Earth must have been significantly closer than that between Earth and aubrites. If the Earth-Moon system evolved from an initially highly vaporized and isotopically homogenized state, as indicated by recent dynamical models, then the terrestrial basalt-lunar oxygen isotope difference detected by our study may be a reflection of post-giant impact additions to Earth. On the basis of this assumption, our data indicate that post-giant impact additions to Earth could have contributed between 5 and 30% of Earth's water, depending on global water estimates. Consequently, our data indicate that the bulk of Earth's water was accreted before the giant impact and not later, as often proposed.

The Making of Deep Impact

NASA Image and Video Library

2006-10-19

This image shows NASA Deep Impact spacecraft being built at Ball Aerospace & Technologies Corporation, Boulder, Colo. on July 2, 2005. The spacecraft impactor was released from Deep Impact flyby spacecraft.

Short arc orbit determination and imminent impactors in the Gaia era

NASA Astrophysics Data System (ADS)

Spoto, F.; Del Vigna, A.; Milani, A.; Tommei, G.; Tanga, P.; Mignard, F.; Carry, B.; Thuillot, W.; David, P.

2018-06-01

Short-arc orbit determination is crucial when an asteroid is first discovered. In these cases usually the observations are so few that the differential correction procedure may not converge. We developed an initial orbit computation method, based on systematic ranging, which is an orbit determination technique that systematically explores a raster in the topocentric range and range-rate space region inside the admissible region. We obtained a fully rigorous computation of the probability for the asteroid that could impact the Earth within a few days from the discovery without any a priori assumption. We tested our method on the two past impactors, 2008 TC3 and 2014 AA, on some very well known cases, and on two particular objects observed by the European Space Agency Gaia mission.

NM-Scale Anatomy of an Entire Stardust Carrot Track

NASA Technical Reports Server (NTRS)

Nakamura-Messenger, K.; Keller, L. P.; Clemett, S. J.; Messenger, S.

2009-01-01

Comet Wild-2 samples collected by NASA s Stardust mission are extremely complex, heterogeneous, and have experienced wide ranges of alteration during the capture process. There are two major types of track morphologies: "carrot" and "bulbous," that reflect different structural/compositional properties of the impactors. Carrot type tracks are typically produced by compact or single mineral grains which survive essentially intact as a single large terminal particle. Bulbous tracks are likely produced by fine-grained or organic-rich impactors [1]. Owing to their challenging nature and especially high value of Stardust samples, we have invested considerable effort in developing both sample preparation and analytical techniques tailored for Stardust sample analyses. Our report focuses on our systematic disassembly and coordinated analysis of Stardust carrot track #112 from the mm to nm-scale.

Simultaneous Red - Blue Lidar and Airborne Impactor Measurements

NASA Technical Reports Server (NTRS)

McCormick, M. P.; Blifford, I. H.; Fuller, W. H.; Grams, G. W.

1973-01-01

Simultaneous two-color (0.6943 micrometers and 0.3472 micrometers) LIDAR measurements were made in the troposphere and lower stratosphere over Boulder, Colorado during March 1973. In addition, on the evening of March 26, airborne single-stage impactor measurements were made at four altitudes-- 10,500, 25,000, 33,000 and 43,000 feet MSL. These data were integrated at constant altitude for 15,45, 45, and 60 minutes respectively. The LIDAR data were taken with Langley's 48" LIDAR using a dichroic beamsplitter to separate the return at 0.6943 micrometers and 0.3472 micrometers. The analog waveforms for both colors were digitized simultaneously; one on an NCAR data acquisition system and the other on the 48" Langley data acquisition system. A discussion of the preliminary results from these measurements will be presented.

Forming a Moon with an Earth-like composition via a giant impact.

PubMed

Canup, Robin M

2012-11-23

In the giant impact theory, the Moon formed from debris ejected into an Earth-orbiting disk by the collision of a large planet with the early Earth. Prior impact simulations predict that much of the disk material originates from the colliding planet. However, Earth and the Moon have essentially identical oxygen isotope compositions. This has been a challenge for the impact theory, because the impactor's composition would have likely differed from that of Earth. We simulated impacts involving larger impactors than previously considered. We show that these can produce a disk with the same composition as the planet's mantle, consistent with Earth-Moon compositional similarities. Such impacts require subsequent removal of angular momentum from the Earth-Moon system through a resonance with the Sun as recently proposed.

Protective Effectiveness of Porous Shields Under the Influence of High-Speed Impact Loading

NASA Astrophysics Data System (ADS)

Kramshonkov, E. N.; Krainov, A. V.; Shorohov, P. V.

2016-02-01

The results of numerical simulations of a compact steel impactor with the aluminum porous shields under high-speed shock loading are presented. The porosity of barrier varies in wide range provided that its mass stays the same, but the impactor has always equal (identical) mass. Here presented the final assessment of the barrier perforation speed depending on its porosity and initial shock speed. The range of initial impact speed varies from 1 to 10 km/s. Physical phenomena such as: destruction, melting, vaporization of a interacting objects are taken into account. The analysis of a shield porosity estimation disclosed that the protection effectiveness of porous shield reveals at the initial impact speed grater then 1.5 km/s, and it increases when initial impact speed growth.

A Miniature System for Separating Aerosol Particles and Measuring Mass Concentrations

PubMed Central

Liang, Dao; Shih, Wen-Pin; Chen, Chuin-Shan; Dai, Chi-An

2010-01-01

We designed and fabricated a new sensing system which consists of two virtual impactors and two quartz-crystal microbalance (QCM) sensors for measuring particle mass concentration and size distribution. The virtual impactors utilized different inertial forces of particles in air flow to classify different particle sizes. They were designed to classify particle diameter, d, into three different ranges: d < 2.28 μm, 2.28 μm ≤ d ≤ 3.20 μm, d > 3.20 μm. The QCM sensors were coated with a hydrogel, which was found to be a reliable adhesive for capturing aerosol particles. The QCM sensor coated with hydrogel was used to measure the mass loading of particles by utilizing its characteristic of resonant frequency shift. An integrated system has been demonstrated. PMID:22319317

Short arc orbit determination and Gaia alerts

NASA Astrophysics Data System (ADS)

Spoto, Federica; Tanga, Paolo; Del Vigna, Alessio; Carry, Benoit; Thuillot, William; David, Pedro; Mignard, Francois; Milani, Andrea; Tommei, Giacomo

2017-10-01

Since October 2016, the short term (ST) processing of Solar System Objects (SSOs) by Gaia is up and running, and it has produced almost 600 alerts. A crucial point in the chain is the possibility of performing a short arc orbit determination as soon as the object has been detected, which allows the follow up of the object from the ground.The method we present has been recentely developed for two mainreasons: 1) search for imminent impactors within the NEO - Confirmation Page(imminent impactors are asteroids that could impact the Earth infew days from their discovery) 2) validation of the SSO-ST Gaia pipeline.We show some good confirmations on objects that could have been discovered by Gaia, and some properties of the Gaia astrometry for the short term.

Constraints on the pre-impact orbits of Solar system giant impactors

NASA Astrophysics Data System (ADS)

Jackson, Alan P.; Gabriel, Travis S. J.; Asphaug, Erik I.

2018-03-01

We provide a fast method for computing constraints on impactor pre-impact orbits, applying this to the late giant impacts in the Solar system. These constraints can be used to make quick, broad comparisons of different collision scenarios, identifying some immediately as low-probability events, and narrowing the parameter space in which to target follow-up studies with expensive N-body simulations. We benchmark our parameter space predictions, finding good agreement with existing N-body studies for the Moon. We suggest that high-velocity impact scenarios in the inner Solar system, including all currently proposed single impact scenarios for the formation of Mercury, should be disfavoured. This leaves a multiple hit-and-run scenario as the most probable currently proposed for the formation of Mercury.

Cratering statistics on asteroids: Methods and perspectives

NASA Astrophysics Data System (ADS)

Chapman, C.

2014-07-01

Crater size-frequency distributions (SFDs) on the surfaces of solid-surfaced bodies in the solar system have provided valuable insights about planetary surface processes and about impactor populations since the first spacecraft images were obtained in the 1960s. They can be used to determine relative age differences between surficial units, to obtain absolute model ages if the impactor flux and scaling laws are understood, to assess various endogenic planetary or asteroidal processes that degrade craters or resurface units, as well as assess changes in impactor populations across the solar system and/or with time. The first asteroid SFDs were measured from Galileo images of Gaspra and Ida (cf., Chapman 2002). Despite the superficial simplicity of these studies, they are fraught with many difficulties, including confusion by secondary and/or endogenic cratering and poorly understood aspects of varying target properties (including regoliths, ejecta blankets, and nearly-zero-g rubble piles), widely varying attributes of impactors, and a host of methodological problems including recognizability of degraded craters, which is affected by illumination angle and by the ''personal equations'' of analysts. Indeed, controlled studies (Robbins et al. 2014) demonstrate crater-density differences of a factor of two or more between experienced crater counters. These inherent difficulties have been especially apparent in divergent results for Vesta from different members of the Dawn Science Team (cf. Russell et al. 2013). Indeed, they have been exacerbated by misuse of a widely available tool (Craterstats: hrscview.fu- berlin.de/craterstats.html), which incorrectly computes error bars for proper interpretation of cumulative SFDs, resulting in derived model ages specified to three significant figures and interpretations of statistically insignificant kinks. They are further exacerbated, and for other small-body crater SFDs analyzed by the Berlin group, by stubbornly adopting certain assumptions about issues that should be left as open questions (e.g., the shapes of impactor SFDs are assumed to be identical throughout the solar system and throughout all epochs, the decay rate of the impactor flux in the asteroid belt is assumed to be the same as in the Earth-Moon system, and all kinks in SFDs are interpreted as ''resurfacings'' rather than due to layering of targets or due to other kinds of crater creation and degradation processes). In fact, we know that there are different mixes of comets and asteroids in different parts of the solar system, that size distributions differ in different parts of the asteroid belt, that SFDs of asteroid families evolve, that kinks in SFDs can be produced by layering (e.g., on the Moon), and that small-scale crater populations on asteroids like Itokawa and Eros are dramatically affected by processes of lesser importance to large-scale cratering (e.g., because of bouldery substrates, seismic shaking, etc.). Identification of homogeneous geological units for crater counting is particularly critical. Crater ejecta blankets, which are useful units on planetary-scale bodies, become problematic on smaller bodies where ejecta travel farther and are even ejected at greater than escape velocity resulting in thin, patchy ejecta blankets inappropriate for displaying a useful post-deposition crater population. As we anticipate studying still more cratered small-body surfaces from future spacecraft and even radar imaging of asteroids, comet nuclei, and small satellites, non-specialists and crater-counters alike should be suspicious of crater SFDs obtained through production-line application of black-box routines like Craterstats. Crater SFDs can still be a very useful tool, so long as there is rigorous, statistically robust, open-minded interpretation that takes account of the real unknowns concerning geological and interplanetary contexts.

Concussion in professional football: animal model of brain injury--part 15.

PubMed

Viano, David C; Hamberger, Anders; Bolouri, Hayde; Säljö, Annette

2009-06-01

A concussion model was developed to study injury mechanisms, functional effects, treatment, and recovery. Concussions in National Football League football involve high-impact velocity (7.4-11.2 m/s) and rapid change in head velocity (DeltaV) (5.4-9.0 m/s). Current animal models do not simulate these head impact conditions. One hundred eight adult male Wistar rats weighing 280 to 350 g were used in ballistic impacts simulating 3 collision severities causing National Football League-type concussion. Pneumatic pressure accelerated a 50 g impactor to velocities of 7.4, 9.3, and 11.2 m/s at the left side of the helmet-protected head. A thin layer of padding on the helmet controlled head acceleration, which was measured on the opposite side of the head, in line with the impact. Peak head acceleration, DeltaV, impact duration, and energy transfer were determined. Fifty-four animals were exposed to single impact, with 18 each having 1, 4, or 10 days of survival. Similar tests were conducted on another 54 animals, which received 3 impacts at 6-hour intervals. An additional 72 animals were tested with a 100g impactor to study more serious brain injuries. Brains were perfused, and surface injuries were identified. The 50 g impactor matches concussion conditions scaled to the rat. Impact velocity and head DeltaV were within 1% and 3% of targets on average. Head acceleration reached 450 g to 1750 g without skull fracture. The test is repeatable and robust. Gross pathology was observed in 11%, 28%, and 33% of animals in the 7.4-, 9.3-, and 11.2-m/s single impacts, respectively. At 7.4 m/s, a single diameter area of less than 0.5 mm of fine petechial hemorrhage occurred on the brain surface in the parenchyma and meninges nearest the point of impact. At higher velocities, there were larger areas of bleeding, sometimes with subdural hemorrhage. When the 50 g impactor tests were examined by logistic regression, greater energy transfer increased the probability of injury (odds ratio, 5.83; P = 0.01), as did 3 repeat impacts (odds ratio, 4.72; P = 0.002). The number of survival days decreased the probability of observing injury (odds ratio, 0.25 and 0.11 for 4 and 10 days, respectively, compared with 1 day). The 100g impactor produced more severe brain injuries. A concussion model was developed to simulate the high velocity of impact and rapid head DeltaV of concussions in National Football League players. The new procedure can be used to evaluate immediate and latent effects of concussion and more severe injury with greater impact mass.

Raman microscopy of size-segregated aerosol particles, collected at the Sonnblick Observatory in Austria

NASA Astrophysics Data System (ADS)

Ofner, Johannes; Kasper-Giebl, Anneliese; Kistler, Magdalena; Matzl, Julia; Schauer, Gerhard; Hitzenberger, Regina; Lohninger, Johann; Lendl, Bernhard

2014-05-01

Size classified aerosol samples were collected using low pressure impactors in July 2013 at the high alpine background site Sonnnblick. The Sonnblick Observatory is located in the Austrian Alps, at the summit of Sonnblick 3100 m asl. Sampling was performed in parallel on the platform of the Observatory and after the aerosol inlet. The inlet is constructed as a whole air inlet and is operated at an overall sampling flow of 137 lpm and heated to 30 °C. Size cuts of the eight stage low pressure impactors were from 0.1 to 12.8 µm a.d.. Alumina foils were used as sample substrates for the impactor stages. In addition to the size classified aerosol sampling overall aerosol mass (Sharp Monitor 5030, Thermo Scientific) and number concentrations (TSI, CPC 3022a; TCC-3, Klotz) were determined. A Horiba LabRam 800HR Raman microscope was used for vibrational mapping of an area of about 100 µm x 100 µm of the alumina foils at a resolution of about 0.5 µm. The Raman microscope is equipped with a laser with an excitation wavelength of 532 nm and a grating with 300 gr/mm. Both optical images and the related chemical images were combined and a chemometric investigation of the combined images was done using the software package Imagelab (Epina Software Labs). Based on the well-known environment, a basic assignment of Raman signals of single particles is possible at a sufficient certainty. Main aerosol constituents e.g. like sulfates, black carbon and mineral particles could be identified. First results of the chemical imaging of size-segregated aerosol, collected at the Sonnblick Observatory, will be discussed with respect to standardized long-term measurements at the sampling station. Further, advantages and disadvantages of chemical imaging with subsequent chemometric investigation of the single images will be discussed and compared to the established methods of aerosol analysis. The chemometric analysis of the dataset is focused on mixing and variation of single compounds at different stages of the impactors.

The cratering record in the inner solar system: Implications for earth

NASA Technical Reports Server (NTRS)

Barlow, N. G.

1988-01-01

Internal and external processes have reworked the Earth's surface throughout its history. In particular, the effect of meteorite impacts on the early history of the earth is lost due to fluvial, aeolian, volcanic and plate tectonic action. The cratering record on other inner solar system bodies often provides the only clue to the relative cratering rates and intensities that the earth has experienced throughout its history. Of the five major bodies within the inner solar system, Mercury, Mars, and the Moon retain scars of an early episode of high impact rates. The heavily cratered regions on Mercury, Mars, and the Moon show crater size-frequency distribution curves similar in shape and crater density, whereas the lightly cratered plains on the Moon and Mars show distribution curves which, although similar to each other, are statistically different in shape and density from the more heavily cratered units. The similarities among crater size-frequency distribution curves for the Moon, Mercury, and Mars suggest that the entire inner solar system was subjected to the two populations of impacting objects but Earth and Venus have lost their record of heavy bombardment impactors. Thus, based on the cratering record on the Moon, Mercury, and Mars, it can be inferred that the Earth experienced a period of high crater rates and basin formation prior to about 3.8 BY ago. Recent studies have linked mass extinctions to large terrestrial impacts, so life forms were unable to establish themselves until impact rates decreased substantially and terrestrial conditions became more benign. The possible periodicity of mass extinctions has led to the theory of fluctuating impact rates due to comet showers in the post heavy bombardment period. The active erosional environment on the Earth complicates attempts to verify these showers by erasing geological evidence of older impact craters. The estimated size of the impactor purportedly responsible for the Cretaceous-Tertiary mass extinctions is 10 km in diameter. Thus impactors greater than or equal to the size postulated for K-T impactor are rare within the inner solar system since the end of heavy bombardment.

Orbital and physical characteristics of meter-scale impactors from airburst observations

NASA Astrophysics Data System (ADS)

Brown, P.; Wiegert, P.; Clark, D.; Tagliaferri, E.

2016-03-01

We have analyzed the orbits and ablation characteristics in the atmosphere of 59 Earth-impacting fireballs, produced by meteoroids 1 m in diameter or larger, described here as meter-scale. Using heights at peak luminosity as a proxy for strength, we determine that there is roughly an order of magnitude spread in strengths of the population of meter-scale impactors at the Earth. We use fireballs producing recovered meteorites and well documented fireballs from ground-based camera networks to calibrate our ablation model interpretation of the observed peak height of luminosity as a function of speed. The orbits and physical strength of these objects are consistent with the majority being asteroidal bodies originating from the inner main asteroid belt. This is in contrast to earlier suggestions by Ceplecha (Ceplecha, Z. [1994]. Astron. Astrophys. 286, 967-970) that the majority of meter-tens of meter sized meteoroids are ;… cometary bodies of the weakest known structure;. We find a lower limit of ∼10-15% of our objects have a possible cometary (Jupiter-Family comet and/or Halley-type comet) origin based on orbital characteristics alone. Only half this number, however, also show evidence for weaker than average structure. Two events, Sumava and USG 20131121, have exceptionally high (relative to the remainder of the population) heights of peak brightness. These are physically most consistent with high microporosity objects, though both were on asteroidal-type orbits. We also find three events, including the Oct 8, 2009 airburst near Sulawesi, Indonesia, which display comparatively low heights of peak brightness, consistent with strong monolithic stones or iron meteoroids. Based on orbital similarity, we find a probable connection among several events in our population with the Taurid meteoroid complex; no other major meteoroid streams show probable linkages to the orbits of our meter-scale population. Our impactors cover almost four orders of magnitude in mass, but no trend in height of peak brightness as a function of mass is evident, suggesting no strong trend in strength with size for meter-scale impactors consistent with the results of Popova et al. (Popova, O.P. et al. [2011]. Meteorit. Planet. Sci. 46, 1525-1550).

Health insurance status and the care of nursing home residents with advanced dementia.

PubMed

Goldfeld, Keith S; Grabowski, David C; Caudry, Daryl J; Mitchell, Susan L

Nursing home residents with advanced dementia commonly experience burdensome and costly hospitalizations that may not extend survival or improve the quality of life. Fragmentation in health care has contributed to poor coordination of care for acutely ill nursing home residents. To compare patterns of care and quality outcomes for nursing home residents with advanced dementia covered by managed care with those covered by traditional fee-for-service Medicare. Choices, Attitudes, and Strategies for Care of Advanced Dementia at the End-of-Life (CASCADE) was a prospective cohort study including 22 nursing homes in the Boston, Massachusetts, area that monitored 323 nursing home residents for 18 months to better understand the course of advanced dementia at or near the end of life. Data from CASCADE and Medicare were linked to determine the health insurance status of study participants. The health insurance status of the resident, either managed care or traditional fee for service. The outcomes included survival, symptoms related to comfort, treatment of pain and dyspnea, presence of pressure ulcers, presence of a do-not-hospitalize order, treatment of pneumonia, hospital transfer (admission or emergency department visit) for an acute illness, hospice referral, primary care visits, and family satisfaction with care. Residents enrolled in managed care (n = 133) were more likely to have do-not-hospitalize orders compared with those in traditional Medicare fee for service (n = 158) (63.7% vs 50.9%; adjusted odds ratio, 1.9; 95% CI, 1.1-3.4), were less likely to be transferred to the hospital for acute illness (3.8% vs 15.7%; adjusted odds ratio, 0.2; 95% CI, 0.1-0.5), had more primary care visits per 90 days (mean [SD], 4.8 [2.6] vs 4.2 [5.0]; adjusted rate ratio, 1.3; 95% CI, 1.1-1.6), and had more nurse practitioner visits (3.0 [2.1] vs 0.8 [2.6]; adjusted rate ratio, 3.0; 95% CI, 2.2-4.1). Survival, comfort, and other treatment outcomes did not differ significantly across groups. CONCLUSIONS AND RELEVANCE Medicare managed-care programs may offer a promising approach to ensure that nursing homes are able to provide appropriate, less burdensome, and affordable care, especially at the end of life.

Health risk characterization for resident inhalation exposure to particle-bound halogenated flame retardants in a typical e-waste recycling zone.

PubMed

Luo, Pei; Bao, Lian-Jun; Wu, Feng-Chang; Li, Shao-Meng; Zeng, Eddy Y

2014-01-01

Inhalation of pollutants is an important exposure route for causing human health hazards, and inhalation exposure assessment must take into account particle size distribution because particle-bound pollutants are size-dependent. Such information is scarce, particularly for residents dwelling within e-waste recycling zones where abundant atmospheric halogenated flame retardants (HFRs) commonly used in electronic/electrical devices have been widely reported. Atmospheric size-fractioned particle samples were collected using a 10-stage Micro-Orifice Uniform Deposit Impactor from an e-waste recycling zone in South China. The deposition efficiencies and fluxes of size-fractioned HFRs including polybrominated diphenyl ethers (PBDEs), alternative brominated flame retardants, and Dechlorane Plus in the human respiratory tract were estimated using the International Commission on Radiological Protection deposition model. The majority of HFRs was found to deposit in the head airways, with coarse particles (aerodynamic diameter (Dp) > 1.8 μm) contributing the most (69-91%). Conversely, fine particles (Dp < 1.8 μm) were dominant in the alveolar region (62-80%). The inhalation intake of PBDEs within the e-waste recycling zone was 44 ng/d (95% confidence interval (CI): 30-65 ng/d), close to those through food consumption in non-e-waste recycling regions. The estimated total hazard quotient of particle-bound HFRs was 5.6 × 10(-4) (95% CI: 3.8 × 10(-4)-8.8 × 10(-4)). In addition, incremental lifetime cancer risk induced by BDE-209 was 1.36 × 10(-10) (95% CI: 7.3 × 10(-11)-2.3 × 10(-10)), much lower than the Safe Acceptable Range (1.0 × 10(-6)-1.0 × 10(-4)) established by the United States Environmental Protection Agency. These results indicate that the potential health risk from inhalation exposure to particle-bound HFRs for residents dwelling in the e-waste recycling zone was low.

Advertising for Demand Creation for Voluntary Medical Male Circumcision.

PubMed

Wilson, Nicholas; Frade, Sasha; Rech, Dino; Friedman, Willa

2016-08-15

To measure the effects of information, a challenge, and a conditional cash transfer on take-up of voluntary medical male circumcision (VMMC). A randomized, controlled experiment with 4000 postcard recipients in Soweto (Johannesburg), South Africa. We examined differences in take-up of several decisions in the VMMC cascade between the control arm and each of several intervention arms using logistic regression. Logistic regression analysis indicated that the group offered US $10 as compensation and the group challenged with "Are you tough enough?" had significantly higher take-up of the VMMC procedure than did the control group [odds ratios, respectively, 5.30 (CI: 2.20 to 12.76) and 2.70 (CI: 1.05 to 6.91)]. Similarly, the compensation group had significantly higher take-up of the VMMC counseling session than did the control group [odds ratio 3.76 (CI: 1.79 to 7.89)]. The analysis did not reveal significantly different take-up of either the VMMC counseling session or the procedure in the partner preference information group compared with the control group [odds ratios, respectively, 1.23 (CI: 0.51 to 2.97) and 1.67 (CI: 0.61 to 4.62)]. The analysis did not reveal significantly higher take-up of the VMMC nurse hotline in any intervention group compared with the control group [odds ratios for US $10, information, and challenge, respectively, 1.17 (CI: 0.67 to 2.07), 0.69 (CI: 0.36 to 1.32), and 0.60 (0.31 to 1.18)]. Among adult males in Soweto, South Africa, compensation of US $10 provided conditional on completing the VMMC counseling session compared with no compensation offer and a postcard with a challenge, "Are you tough enough?" compared with no challenge, resulted in moderate increases in take-up of circumcision.

Finite element analysis of unnotched charpy impact tests

DOT National Transportation Integrated Search

2008-10-01

This paper describes nonlinear finite element analysis (FEA) to examine the energy to : fracture unnotched Charpy specimens under pendulum impact loading. An oversized, : nonstandard pendulum impactor, called the Bulk Fracture Charpy Machine (BFCM), ...

Psyche: State of Knowledge from Ground-Based Observations

NASA Astrophysics Data System (ADS)

Reddy, V.; Shepard, M. K.; Takir, D.; Sanchez, J. A.; Richardson, J.; Emery, J. P.; Taylor, P. A.

2017-07-01

We present results from a multi-year campaign to characterize asteroid (16) Psyche, the target of NASA Discovery mission. Our results suggest that Psyche is covered with exogenic carbonaceous impactor similar to Vesta.

Geologic signatures of atmospheric effects on impact cratering on Venus

NASA Technical Reports Server (NTRS)

1996-01-01

Highlights of the research include geologic signatures of impact energy and atmospheric response to crater formation. Laboratory experiments were performed at the NASA Ames Vertical Gun Range (AVGR) to assess the interaction between disrupted impactor and atmosphere during entry, and to assess the energy coupling between impacts and the surrounding atmosphere. The Schlieren imaging at the AVGR was used in combination with Magellan imaging and theoretical studies to study the evolution of the impactor following impact. The Schlieren imaging documented the downrange blast front created by vaporization during oblique impacts. Laboratory experiments allowed assessing the effect of impact angle on coupling efficiency with an atmosphere. And the impact angle's effect on surface blasts and run-out flows allowed the distinction of crater clusters created by simultaneous impacts from those created by isolated regions of older age.

Time dependent response of low velocity impact induced composite conical shells under multiple delamination

NASA Astrophysics Data System (ADS)

Dey, Sudip; Karmakar, Amit

2014-02-01

This paper presents the time dependent response of multiple delaminated angle-ply composite pretwisted conical shells subjected to low velocity normal impact. The finite element formulation is based on Mindlin's theory incorporating rotary inertia and effects of transverse shear deformation. An eight-noded isoparametric plate bending element is employed to satisfy the compatibility of deformation and equilibrium of resultant forces and moments at the delamination crack front. A multipoint constraint algorithm is incorporated which leads to asymmetric stiffness matrices. The modified Hertzian contact law which accounts for permanent indentation is utilized to compute the contact force, and the time dependent equations are solved by Newmark's time integration algorithm. Parametric studies are conducted with respect to triggering parameters like laminate configuration, location of delamination, angle of twist, velocity of impactor, and impactor's displacement for centrally impacted shells.

Micrometeoroid Impacts on the Hubble Sace Telescope Wide Field and Planetary Camera 2: Ion Beam Analysis of Subtle Impactor Traces

NASA Technical Reports Server (NTRS)

Grime, G. W.; Webb, R. P.; Jeynes, C.; Palitsin, V. V.; Colaux, J. L.; Kearsley, A. T.; Ross, D. K.; Anz-Meador, P.; Liou, J. C.; Opiela, J.;

OLYMPEX Counterflow Spectrometer and Impactor Field Campaign Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poellot, Michael

The U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility’s ARM Aerial Facility (AAF) Counterflow Spectrometer and Impactor (CSI) probe was flown on the University of North Dakota Cessna Citation research aircraft during the Olympic Mountain Experiment (OLYMPEX). The field campaign took place from November 12 through December 19, 2015, over the Olympic Mountains and coastal waters of Washington State as part of a National Aeronautics and Space Administration (NASA) Global Precipitation Measurement (GPM) validation campaign. The CSI was added to the Citation instrument suite to support the NASA Aerosol-Cloud Ecosystem (ACE) satellite program and flights ofmore » the NASA Lockheed Earth Resources (ER-2) aircraft. ACE funded extra ER-2 flights to focus on clouds that are weakly precipitating, which are also of interest to the DOE Atmospheric System Research (ASR) program.« less

Fundamental Physics

NASA Image and Video Library

2003-01-22

Clues to the formation of planets and planetary rings -- like Saturn's dazzling ring system -- may be found by studying how dust grains interact as they collide at low speeds. To study the question of low-speed dust collisions, NASA sponsored the COLLisions Into Dust Experiment (COLLIDE) at the University of Colorado. It was designed to spring-launch marble-size projectiles into trays of powder similar to space or lunar dust. COLLIDE-1 (1998) discovered that collisions below a certain energy threshold eject no material. COLLIDE-2 was designed to identify where the threshold is. In COLLIDE-2, scientists nudged small projectiles into dust beds and recorded how the dust splashed outward (video frame at top; artist's rendering at bottom). The slowest impactor ejected no material and stuck in the target. The faster impactors produced ejecta; some rebounded while others stuck in the target.

Low Velocity Impacts of Variable Tip Radius on Carbon/Epoxy Plates

NASA Astrophysics Data System (ADS)

Delaney, Mac P.

With a growing use of composite materials in aircraft structures, there is a greater need to understand the response of these materials to low velocity impacts. Low velocity impacts from tool drops or ground equipment collisions can be of varying bluntness and can leave little or no visible evidence of damage. Therefore, a need exists to investigate the initiation of internal damage and the relationship between this internal damage and the external visible damage with respect to the bluntness of the impactor. A pendulum impactor was used to impact 76.2 x 127 mm carbon/epoxy panels that were 8, 16, and 24 plies thick. The panels were impacted by hardened steel tips with radii of 12.7 to 76.2 mm. The experimental results show that the failure threshold energies for each panel thickness and tip radius combination occur at a distinct and consistent energy. This threshold increases with impactor bluntness, and this effect is greater for the 8 ply panel than it is for the 16 or 24 ply panels. To describe the visibility of impact damage, the area of delamination was compared to the depth of the dents resulting from the impacts. For the sharper impact tips, there is a clear relationship between the delamination area and the depth of the dents. However, these relationships are dependent on the radius of the impact tip, and for the blunter impact tips no strong correlation could be determined between the delamination area and the depth of the dents.

New insights on petrography and geochemistry of impactites from the Lonar crater, India

NASA Astrophysics Data System (ADS)

Ray, Dwijesh; Upadhyay, Dewashish; Misra, Saumitra; Newsom, Horton E.; Ghosh, Sambhunath

2017-08-01

The Lonar impact crater, India, is one of the few known terrestrial impact craters excavated in continental basaltic target rocks (Deccan Traps, 65 Ma). The impactites reported from the crater to date mainly include centimeter- to decimeter-sized impact-melt bombs, and aerodynamically shaped millimeter- and submillimeter-sized impact spherules. They occur in situ within the ejecta around the crater rim and show schlieren structure. In contrast, non-in situ glassy objects, loosely strewn around the crater lake and in the ejecta around the crater rim do not show any schlieren structure. These non-in situ fragments appear to be similar to ancient bricks from the Daityasudan temple in the Lonar village. Synthesis of existing and new major and trace element data on the Lonar impact spherules show that (1) the target Lonar basalts incorporated into the spherules had undergone minimal preimpact alteration. Also, the paleosol layer as preserved between the top-most target basalt flow and the ejecta blanket, even after the impact, was not a source component for the Lonar impactites, (2) the Archean basement below the Deccan traps were unlikely to have contributed material to the impactite parental melts, and (3) the impactor asteroid components (Cr, Co, Ni) were concentrated only within the submillimeter-sized spherules. Two component mixing calculations using major oxides and Cr, Co, and Ni suggest that the Lonar impactor was a EH-type chondrite with the submillimeter-sized spherules containing 6 wt% impactor components.

Characterization of a Regenerable Impactor Filter for Spacecraft Cabin Applications

NASA Technical Reports Server (NTRS)

Agui, Juan H.; Vijayakumar, R.

2015-01-01

Regenerable filters will play an important role in human exploration beyond low-Earth orbit. Life Support Systems aboard crewed spacecrafts will have to operate reliably and with little maintenance over periods of more than a year, even multiple years. Air filters are a key component of spacecraft life support systems, but they often require frequent routine maintenance. Bacterial filters aboard the International Space Station require almost weekly cleaning of the pre-filter screen to remove large lint debris captured in the microgravity environment. The source of the airborne matter which is collected on the filter screen is typically from clothing fibers, biological matter (hair, skin, nails, etc.) and material wear. Clearly a need for low maintenance filters requiring little to no crew intervention will be vital to the success of the mission. An impactor filter is being developed and tested to address this need. This filter captures large particle matter through inertial separation and impaction methods on collection surfaces, which can be automatically cleaned after they become heavily loaded. The impactor filter can serve as a pre-filter to augment the life of higher efficiency filters that capture fine and ultrafine particles. A prototype of the filter is being tested at the Particulate Filtration Laboratory at NASA Glenn Research Center to determine performance characteristics, including particle cut size and overall efficiency. Model results are presented for the flow characteristics near the orifice plate through which the particle-laden flow is accelerated as well as around the collection bands.

Oxygen isotopic evidence for accretion of Earth’s water before a high-energy Moon-forming giant impact

PubMed Central

Barrat, Jean-Alix; Sillard, Patrick; Starkey, Natalie A.

2018-01-01

The Earth-Moon system likely formed as a result of a collision between two large planetary objects. Debate about their relative masses, the impact energy involved, and the extent of isotopic homogenization continues. We present the results of a high-precision oxygen isotope study of an extensive suite of lunar and terrestrial samples. We demonstrate that lunar rocks and terrestrial basalts show a 3 to 4 ppm (parts per million), statistically resolvable, difference in Δ17O. Taking aubrite meteorites as a candidate impactor material, we show that the giant impact scenario involved nearly complete mixing between the target and impactor. Alternatively, the degree of similarity between the Δ17O values of the impactor and the proto-Earth must have been significantly closer than that between Earth and aubrites. If the Earth-Moon system evolved from an initially highly vaporized and isotopically homogenized state, as indicated by recent dynamical models, then the terrestrial basalt-lunar oxygen isotope difference detected by our study may be a reflection of post–giant impact additions to Earth. On the basis of this assumption, our data indicate that post–giant impact additions to Earth could have contributed between 5 and 30% of Earth’s water, depending on global water estimates. Consequently, our data indicate that the bulk of Earth’s water was accreted before the giant impact and not later, as often proposed. PMID:29600271

Lessons Learned from Daily Uplink Operations during the Deep Impact Mission

NASA Technical Reports Server (NTRS)

Stehly, Joseph S.

2006-01-01

The daily preparation of uplink products (commands and files) for Deep Impact was as problematic as the final encounter images were spectacular. The operations team was faced with many challenges during the six-month mission to comet Tempel One of the biggest difficulties was that the Deep Impact Flyby and Impactor vehicles necessitated a high volume of uplink products while also utilizing a new uplink file transfer capability. The Jet Propulsion Laboratory (JPL) Multi-Mission Ground Systems and Services (MGSS) Mission Planning and Sequence Team (MPST) had the responsibility of preparing the uplink products for use on the two spacecraft. These responsibilities included processing nearly 15,000 flight products, modeling the states of the spacecraft during all activities for subsystem review, and ensuring that the proper commands and files were uplinked to the spacecraft. To guarantee this transpired and the health and safety of the two spacecraft were not jeopardized several new ground scripts and procedures were developed while the Deep Impact Flyby and Impactor spacecraft were en route to their encounter with Tempel-1. These scripts underwent several adaptations throughout the entire mission up until three days before the separation of the Flyby and Impactor vehicles. The problems presented by Deep Impact's daily operations and the development of scripts and procedures to ease those challenges resulted in several valuable lessons learned. These lessons are now being integrated into the design of current and future MGSS missions at JPL.

Geochemical arguments for an Earth-like Moon-forming impactor

PubMed Central

Dauphas, Nicolas; Burkhardt, Christoph; Warren, Paul H.; Fang-Zhen, Teng

2014-01-01

Geochemical evidence suggests that the material accreted by the Earth did not change in nature during Earth's accretion, presumably because the inner protoplanetary disc had uniform isotopic composition similar to enstatite chondrites, aubrites and ungrouped achondrite NWA 5363/5400. Enstatite meteorites and the Earth were derived from the same nebular reservoir but diverged in their chemical evolutions, so no chondrite sample in meteorite collections is representative of the Earth's building blocks. The similarity in isotopic composition (Δ17O, ε50Ti and ε54Cr) between lunar and terrestrial rocks is explained by the fact that the Moon-forming impactor came from the same region of the disc as other Earth-forming embryos, and therefore was similar in isotopic composition to the Earth. The heavy δ30Si values of the silicate Earth and the Moon relative to known chondrites may be due to fractionation in the solar nebula/protoplanetary disc rather than partitioning of silicon in Earth's core. An inversion method is presented to calculate the Hf/W ratios and ε182W values of the proto-Earth and impactor mantles for a given Moon-forming impact scenario. The similarity in tungsten isotopic composition between lunar and terrestrial rocks is a coincidence that can be explained in a canonical giant impact scenario if an early formed embryo (two-stage model age of 10–20 Myr) collided with the proto-Earth formed over a more protracted accretion history (two-stage model age of 30–40 Myr). PMID:25114316

Molecular comparison of the sampling efficiency of four types of airborne bacterial samplers.

PubMed

Li, Kejun

2011-11-15

In the present study, indoor and outdoor air samples were collected using four types of air samplers often used for airborne bacterial sampling. These air samplers included two solid impactors (BioStage and RCS), one liquid impinger (BioSampler), and one filter sampler with two kinds of filters (a gelatin and a cellulose acetate filter). The collected air samples were further processed to analyze the diversity and abundance of culturable bacteria and total bacteria through standard culture techniques, denaturing gradient gel electrophoresis (DGGE) fingerprinting and quantitative polymerase chain reaction (qPCR) analysis. The DGGE analysis indicated that the air samples collected using the BioStage and RCS samplers have higher culturable bacterial diversity, whereas the samples collected using the BioSampler and the cellulose acetate filter sampler have higher total bacterial diversity. To obtain more information on the sampled bacteria, some gel bands were excised and sequenced. In terms of sampling efficiency, results from the qPCR tests indicated that the collected total bacterial concentration was higher in samples collected using the BioSampler and the cellulose acetate filter sampler. In conclusion, the sampling bias and efficiency of four kinds of air sampling systems were compared in the present study and the two solid impactors were concluded to be comparatively efficient for culturable bacterial sampling, whereas the liquid impactor and the cellulose acetate filter sampler were efficient for total bacterial sampling. Copyright © 2011 Elsevier B.V. All rights reserved.

Dry powder inhalers of gentamicin and leucine: formulation parameters, aerosol performance and in vitro toxicity on CuFi1 cells.

PubMed

Aquino, R P; Prota, L; Auriemma, G; Santoro, A; Mencherini, T; Colombo, G; Russo, P

2012-04-15

The high hygroscopicity of gentamicin (G) as raw material hampers the production of respirable particles during aerosol generation and prevents its direct use as powder for inhalation in patients suffering from cystic fibrosis (CF). Therefore, this research aimed to design a new dry powder formulation of G studying dispersibility properties of an aminoacid, L-leucine (leu), and appropriate process conditions. Spray-dried powders were characterized as to water uptake, particle size distribution, morphology and stability, in correlation with process parameters. Aerodynamic properties were analyzed both by Single Stage Glass Impinger and Andersen Cascade Impactor. Moreover, the potential cytotoxicity on bronchial epithelial cells bearing a CFTR F508/F508 mutant genotype (CuFi1) were tested. Results indicated that leu may improve the aerosol performance of G-dried powders. The maximum fine particle fraction (FPF) of about 58.3% was obtained when water/isopropyl alcohol 7:3 system and 15-20% (w/w) of leu were used, compared to a FPF value of 13.4% for neat G-dried powders. The enhancement of aerosol efficiency was credited both to the improvement of the powder flowability, caused by the dispersibility enhancer (aminoacid), and to the modification of the particle surface due to the influence of the organic co-solvent on drying process. No significant degradation of the dry powder was observed up to 6 months of storage. Moreover, particle engineering did not affect either the cell viability or cell proliferation of CuFi1 over a 24 h period. Copyright © 2012 Elsevier B.V. All rights reserved.

[The "silica" component in the PM10 of an urban site].

PubMed

De Berardis, Barbara; Incocciati, Emma; Massera, S; Gargaro, G; Paoletti, L

2007-01-01

In vivo and in vitro toxicological studies have shown that the aged fracturated crystalline silica, which is a component of airborne particulate, exerts an important inflammatory action on airways. The evaluation of the concentration level of airborne crystalline silica in an urban area is an important research subject in order to determine the exposure levels of the general population. The aim was to study the seasonal trend of the quartz (the most common form of crystalline silica) concentration levels in the particulate inhalable faction (PM10) in the urban area of Rome. PM10, sampled by a cascade impactor, was analysed by scanning electron microscopy, equipped with a thin-window system for X-ray microanalysis (SEM/EDX) for qualitative analysis. Parallely the concentration levels of quartz in the particulate were determined by X-ray diffractometry (XRD) for quantitative analysis, using the NIOSH 7500 method (NIOSH, 1994). From September 2004 to October 2005 the abundance of silica particles, evaluated by SEM/EDX was in the range 1.6/10.4%, with a concentration level of free crystalline silica in the range 0.25/2.87 microg/mi. The equivalent diameter of silica particles ranged from 0.3 to 10.5 mircom, moreover, more than 87% of particles showed a diameter less than 2.5 microm. The correlations between SEM/EDX and XRD data seem to suggest that the airborne silica particles in the urban location studied consisted mostly of crystalline silica. Moreover, the data suggest the existence of a significant contribution of silica particles due to southwest wind carrying a fine dust from the Sahara desert to Mediterranean Europe.

In vitro inflammatory and cytotoxic effects of size-segregated particulate samples collected during long-range transport of wildfire smoke to Helsinki

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jalava, Pasi I.; Salonen, Raimo O.; Haelinen, Arja I.

2006-09-15

The impact of long-range transport (LRT) episodes of wildfire smoke on the inflammogenic and cytotoxic activity of urban air particles was investigated in the mouse RAW 264.7 macrophages. The particles were sampled in four size ranges using a modified Harvard high-volume cascade impactor, and the samples were chemically characterized for identification of different emission sources. The particulate mass concentration in the accumulation size range (PM{sub 1-0.2}) was highly increased during two LRT episodes, but the contents of total and genotoxic polycyclic aromatic hydrocarbons (PAH) in collected particulate samples were only 10-25% of those in the seasonal average sample. The abilitymore » of coarse (PM{sub 10-2.5}), intermodal size range (PM{sub 2.5-1}), PM{sub 1-0.2} and ultrafine (PM{sub 0.2}) particles to cause cytokine production (TNF{alpha}, IL-6, MIP-2) reduced along with smaller particle size, but the size range had a much smaller impact on induced nitric oxide (NO) production and cytotoxicity or apoptosis. The aerosol particles collected during LRT episodes had a substantially lower activity in cytokine production than the corresponding particles of the seasonal average period, which is suggested to be due to chemical transformation of the organic fraction during aging. However, the episode events were associated with enhanced inflammogenic and cytotoxic activities per inhaled cubic meter of air due to the greatly increased particulate mass concentration in the accumulation size range, which may have public health implications.« less

Preclinical safety evaluation of submicronized sildenafil citrate nebulization solution in small experimental animals.

PubMed

Agrawal, Priyanka; Soni, Sandeep; Mittal, Gaurav; Bhatnagar, Aseem

2015-01-01

Sildenafil citrate (SC) nebulization solution has the potential to treat pulmonary hypertension by delivering high concentration directly to the respiratory system while minimizing systemic drug exposure and associated toxicity. The objective of the present study was to evaluate the potential toxicity of aerosolized SC (inhaled) in Sprague dawley rats for 28 days. The rats were randomly divided into five groups (n = 6). Placebo (normal saline) was inhaled to group I (control). Group II was exposed to therapeutic dose (TD): 20 mg/kg, while group 3 and group 4 were exposed to 3 TD and 6 TD, respectively, till 28 days and toxicokinetic parameters were evaluated in group V. The particle size of the nebulized solution of SC (1%) was measured by using Anderson Cascade Impactor. At the end of experiment, all animals were sacrificed. Endpoints used to evaluate potential toxicity of inhaled sildenafil citrate were clinical observations, body weight, and clinical pathology along with broncho-alveolar lavage (BAL) Fluid investigation. ACI study has shown that more than 70% aerosolized drug particles were in submicron range (0.3-0.5 μm). There was no systemic toxicity or clinically limiting local respiratory toxicity associated with inhalation exposure to SC nebulization solution at 6 TD. No significant changes were observed in the level of different blood and BALF parameters in treated groups in comparison to control. Histopathological examination revealed no abnormal findings in the animals of treated group. The data demonstrate that aerosolized sildenafil citrate is well tolerated in rats and suggest its use in humans.

Pesticides in the atmosphere: a comparison of gas-particle partitioning and particle size distribution of legacy and current-use pesticides

NASA Astrophysics Data System (ADS)

Degrendele, C.; Okonski, K.; Melymuk, L.; Landlová, L.; Kukučka, P.; Audy, O.; Kohoutek, J.; Čupr, P.; Klánová, J.

2016-02-01

This study presents a comparison of seasonal variation, gas-particle partitioning, and particle-phase size distribution of organochlorine pesticides (OCPs) and current-use pesticides (CUPs) in air. Two years (2012/2013) of weekly air samples were collected at a background site in the Czech Republic using a high-volume air sampler. To study the particle-phase size distribution, air samples were also collected at an urban and rural site in the area of Brno, Czech Republic, using a cascade impactor separating atmospheric particulates according to six size fractions. Major differences were found in the atmospheric distribution of OCPs and CUPs. The atmospheric concentrations of CUPs were driven by agricultural activities while secondary sources such as volatilization from surfaces governed the atmospheric concentrations of OCPs. Moreover, clear differences were observed in gas-particle partitioning; CUP partitioning was influenced by adsorption onto mineral surfaces while OCPs were mainly partitioning to aerosols through absorption. A predictive method for estimating the gas-particle partitioning has been derived and is proposed for polar and non-polar pesticides. Finally, while OCPs and the majority of CUPs were largely found on fine particles, four CUPs (carbendazim, isoproturon, prochloraz, and terbuthylazine) had higher concentrations on coarse particles ( > 3.0 µm), which may be related to the pesticide application technique. This finding is particularly important and should be further investigated given that large particles result in lower risks from inhalation (regardless the toxicity of the pesticide) and lower potential for long-range atmospheric transport.

Particle Morphology From Wood-Burning Cook Stoves Emissions

NASA Astrophysics Data System (ADS)

Peralta, O.; Carabali, G.; Castro, T.; Torres, R.; Ruiz, L. G.; Molina, L. T.; Saavedra, I.

2013-12-01

Emissions from three wood-burning cook stoves were sampled to collect particles. Transmission electron microscope (TEM) copper grids were placed on the last two stages of an 8-stage MOUDI cascade impactor (d50= 0.32, and 0.18 μm). Samples were obtained on two heating stages of cooking, the first is a quick heating process to boil 1 liter of water, and the second is to keep the water at 90 C. Absorption coefficient, scattering coefficients, and particles concentration (0.01 - 2.5 μm aerodynamic diameter) were measured simultaneously using an absorption photometer (operated at 550 nm), a portable integrating nephelometer (at 530 nm), and a condensation particle counter connected to a chamber to dilute the wood stoves emissions. Transmission electron micrographic images of soot particles were acquired at different magnifications using a High Resolution Transmission Electron Microscope (HRTEM) JEOL HRTEM 4000EX operating at 200 kV, equipped with a GATAN digital micrograph system for image acquisition. The morphology of soot particles was analyzed calculating the border-based fractal dimension (Df). Particles sampled on the first heating stage exhibit complex shapes with high values of Df, which are present as aggregates formed by carbon ceno-spheres. The presence of high numbers of carbon ceno-spheres can be attributed to pyrolysis, thermal degradation, and others processes prior to combustion. Energy dispersive X-ray spectroscopy (EDS) was used to determine the elemental composition of particles. EDS analysis in particles with d50= 0.18 μm showed a higher content of carbonaceous material and relevant amounts of Si, S and K.

[Distribution of airborne fungi, particulate matter and carbon dioxide in Seoul metropolitan subway stations].

PubMed

Kim, Ki Youn; Park, Jae Beom; Kim, Chi Nyon; Lee, Kyung Jong

2006-07-01

The aims of this study were to examine the level of airborne fungi and environmental factors in Seoul metropolitan subway stations and to provide fundamental data to protect the health of subway workers and passengers. The field survey was performed from November in 2004 to February in 2005. A total 22 subway stations located at Seoul subway lines 1-4 were randomly selected. The measurement points were subway workers' activity areas (station office, bedroom, ticket office and driver's seat) and the passengers' activity areas (station precincts, inside train and platform). Air sampling for collecting airborne fungi was carried out using a one-stage cascade impactor. The PM and CO2 were measured using an electronic direct recorder and detecting tube, respectively. In the activity areas of the subway workers and passengers, the mean concentrations of airborne fungi were relatively higher in the workers' bedroom and station precinct whereas the concentration of particulate matter, PM10 and PM2.5, were relatively higher in the platform, inside the train and driver's seat than in the other activity areas. There was no significant difference in the concentration of airborne fungi between the underground and ground activity areas of the subway. The mean PM10 and PM2.5 concentration in the platform located at underground was significantly higher than that of the ground (p<0.05). The levels of airborne fungi in the Seoul subway line 1-4 were not serious enough to cause respiratory disease in subway workers and passengers. This indicates that there is little correlation between airborne fungi and particulate matter.

Implementation of an Algorithm for Prosthetic Joint Infection: Deviations and Problems.

PubMed

Mühlhofer, Heinrich M L; Kanz, Karl-Georg; Pohlig, Florian; Lenze, Ulrich; Lenze, Florian; Toepfer, Andreas; von Eisenhart-Rothe, Ruediger; Schauwecker, Johannes

The outcome of revision surgery in arthroplasty is based on a precise diagnosis. In addition, the treatment varies based on whether the prosthetic failure is caused by aseptic or septic loosening. Algorithms can help to identify periprosthetic joint infections (PJI) and standardize diagnostic steps, however, algorithms tend to oversimplify the treatment of complex cases. We conducted a process analysis during the implementation of a PJI algorithm to determine problems and deviations associated with the implementation of this algorithm. Fifty patients who were treated after implementing a standardized algorithm were monitored retrospectively. Their treatment plans and diagnostic cascades were analyzed for deviations from the implemented algorithm. Each diagnostic procedure was recorded, compared with the algorithm, and evaluated statistically. We detected 52 deviations while treating 50 patients. In 25 cases, no discrepancy was observed. Synovial fluid aspiration was not performed in 31.8% of patients (95% confidence interval [CI], 18.1%-45.6%), while white blood cell counts (WBCs) and neutrophil differentiation were assessed in 54.5% of patients (95% CI, 39.8%-69.3%). We also observed that the prolonged incubation of cultures was not requested in 13.6% of patients (95% CI, 3.5%-23.8%). In seven of 13 cases (63.6%; 95% CI, 35.2%-92.1%), arthroscopic biopsy was performed; 6 arthroscopies were performed in discordance with the algorithm (12%; 95% CI, 3%-21%). Self-critical analysis of diagnostic processes and monitoring of deviations using algorithms are important and could increase the quality of treatment by revealing recurring faults.

49 CFR 572.186 - Abdomen assembly.

Code of Federal Regulations, 2014 CFR

2014-10-01

... longitudinal axis of the probe's impact face as shown in Figure U5-A in appendix A to this subpart; (4) The... the three load cell forces must be concurrent in time. (2) Maximum impactor force (impact probe...

Further Mapping of Mercury's Crustal Magnetic Field Using MESSENGER Magnetometer Data

NASA Astrophysics Data System (ADS)

Hood, L. L.; Oliveira, J. S.; Spudis, P. D.; Galluzzi, V.

2018-05-01

Further mapping of Mercury's crustal magnetic field shows that anomalies are associated with some impact craters but not others. Differences in impactor composition (e.g., iron content) may be indicated by this new observation.

Evaluation of a Portable Photometer for Estimating Diesel Particulate Matter Concentrations in an Underground Limestone Mine

PubMed Central

Watts, Winthrop F.; Gladis, David D.; Schumacher, Matthew F.; Ragatz, Adam C.; Kittelson, David B.

2010-01-01

A low cost, battery-operated, portable, real-time aerosol analyzer is not available for monitoring diesel particulate matter (DPM) concentrations in underground mines. This study summarizes a field evaluation conducted at an underground limestone mine to evaluate the potential of the TSI AM 510 portable photometer (equipped with a Dorr-Oliver cyclone and 1.0-μm impactor) to qualitatively track time-weighted average mass and elemental, organic, and total carbon (TC) measurements associated with diesel emissions. The calibration factor corrected correlation coefficient (R2) between the underground TC and photometer measurements was 0.93. The main issues holding back the use of a photometer for real-time estimation of DPM in an underground mine are the removal of non-DPM-associated particulate matter from the aerosol stream using devices, such as a cyclone and/or impactor and calibration of the photometer to mine-specific aerosol. PMID:20410071

An asteroid breakup 160 Myr ago as the probable source of the K/T impactor.

PubMed

Bottke, William F; Vokrouhlický, David; Nesvorný, David

2007-09-06

The terrestrial and lunar cratering rate is often assumed to have been nearly constant over the past 3 Gyr. Different lines of evidence, however, suggest that the impact flux from kilometre-sized bodies increased by at least a factor of two over the long-term average during the past approximately 100 Myr. Here we argue that this apparent surge was triggered by the catastrophic disruption of the parent body of the asteroid Baptistina, which we infer was a approximately 170-km-diameter body (carbonaceous-chondrite-like) that broke up 160(-20)+30Myr ago in the inner main asteroid belt. Fragments produced by the collision were slowly delivered by dynamical processes to orbits where they could strike the terrestrial planets. We find that this asteroid shower is the most likely source (>90 per cent probability) of the Chicxulub impactor that produced the Cretaceous/Tertiary (K/T) mass extinction event 65 Myr ago.

Environmental effects of large impacts on Mars.

PubMed

Segura, Teresa L; Toon, Owen B; Colaprete, Anthony; Zahnle, Kevin

2002-12-06

The martian valley networks formed near the end of the period of heavy bombardment of the inner solar system, about 3.5 billion years ago. The largest impacts produced global blankets of very hot ejecta, ranging in thickness from meters to hundreds of meters. Our simulations indicated that the ejecta warmed the surface, keeping it above the freezing point of water for periods ranging from decades to millennia, depending on impactor size, and caused shallow subsurface or polar ice to evaporate or melt. Large impacts also injected steam into the atmosphere from the craters or from water innate to the impactors. From all sources, a typical 100-, 200-, or 250-kilometers asteroid injected about 2, 9, or 16 meters, respectively, of precipitable water into the atmosphere, which eventually rained out at a rate of about 2 meters per year. The rains from a large impact formed rivers and contributed to recharging aquifers.

Impact-Mobilized Dust in the Martian Atmosphere

NASA Technical Reports Server (NTRS)

Nemtchinov, I. V.; Shuvalov, V. V.; Greeley, R.

2002-01-01

We consider dust production and entrainment into the atmosphere of Mars by impacts. Numerical simulations based on the multidimensional multimaterial hydrocode were conducted for impactors 1 to 100 m in size and velocities 11 and 20 kilometers per second. The size distribution of particles was based on experimentrr wing TNT explosions. Dust can be mobilized even when the impactor does not reach the ground through the release of energy in the atmosphere, We found that the blast produced winds entrained dust by a mechanism similar to boundary layer winds as determined from the wind-tunnel tests. For a l-m radius stony asteroid releasing its energy in the atmosphere the lifted mass of dust is larger than that in a typical dust devil and could trigger local dust storms, For a 100-m-radius meteoroid the amount of injected dust is comparable with the tota! mass of a global dust storm.

Calibration correction of an active scattering spectrometer probe to account for refractive index of stratospheric aerosols

NASA Technical Reports Server (NTRS)

Pueschel, R. F.; Overbeck, V. R.; Snetsinger, K. G.; Russell, P. B.; Ferry, G. V.

1990-01-01

The use of the active scattering spectrometer probe (ASAS-X) to measure sulfuric acid aerosols on U-2 and ER-2 research aircraft has yielded results that are at times ambiguous due to the dependence of particles' optical signatures on refractive index as well as physical dimensions. The calibration correction of the ASAS-X optical spectrometer probe for stratospheric aerosol studies is validated through an independent and simultaneous sampling of the particles with impactors; sizing and counting of particles on SEM images yields total particle areas and volumes. Upon correction of calibration in light of these data, spectrometer results averaged over four size distributions are found to agree with similarly averaged impactor results to within a few percent: indicating that the optical properties or chemical composition of the sample aerosol must be known in order to achieve accurate optical aerosol spectrometer size analysis.

Dispersion of Projectile and Target Debris Upon Penetration of Thin Targets

NASA Astrophysics Data System (ADS)

Gwynn, D.; Bernhard, R. P.; See, T. H.; Horz, F.

1996-03-01

We continue to conduct penetration experiments of thin foils to support the development of cosmic-dust flight instruments that utilize thin films for the measurement of particle trajectories, or for the potential soft capture of hypervelocity impactors for subsequent compositional analysis upon retrieval to Earth. Each experiment is equipped with a witness plate, mounted to the rear of the target and fabricated from soft Aluminum-1100, ~30 x 30 cm in size and ranging from 2 to 5 mm thick; these witness plates essentially simulate the rear wall of a capture cell onto which the projectile material will plate out, including material that is being dislodged from the penetrated foil itself. Using compositionally contrasting projectile and foil materials in the laboratory, such as soda-lime glass impactors and aluminum targets, one produces two distinct populations of craters on the witness plates.

Melting, vaporization, and energy partitioning for impacts on asteroidal and planetary objects

NASA Technical Reports Server (NTRS)

Smither, Catherine L.; Ahrens, Thomas J.

1992-01-01

A three-dimensional smoothed particle hydrodynamics code was used to model normal and oblique impacts of silicate projectiles on asteroidal and planetary bodies. The energy of the system, initially in the kinetic energy of the impactor, is partitioned after impact into internal and kinetic energy of the impactor and the target body. These simulations show that, unlike the case of impacts onto a half-space, a significant amount of energy remains in the kinetic energy of the impacting body, as parts of it travel past the main planet and escape the system. This effect is greater for more oblique impacts, and for impacts onto the small planets. Melting and vaporization of both bodies were also examined. The amount of the target body melted was much greater in the case of smaller targets than for an impact of a similar scale on a larger body.

The missing impact craters on Venus

NASA Technical Reports Server (NTRS)

Speidel, D. H.

1993-01-01

The size-frequency pattern of the 842 impact craters on Venus measured to date can be well described (across four standard deviation units) as a single log normal distribution with a mean crater diameter of 14.5 km. This result was predicted in 1991 on examination of the initial Magellan analysis. If this observed distribution is close to the real distribution, the 'missing' 90 percent of the small craters and the 'anomalous' lack of surface splotches may thus be neither missing nor anomalous. I think that the missing craters and missing splotches can be satisfactorily explained by accepting that the observed distribution approximates the real one, that it is not craters that are missing but the impactors. What you see is what you got. The implication that Venus crossing impactors would have the same type of log normal distribution is consistent with recently described distribution for terrestrial craters and Earth crossing asteroids.

Research on Impact Stress and Fatigue Simulation of a New Down-to-the-Hole Impactor Based on ANSYS

NASA Astrophysics Data System (ADS)

Wu, Tao; Wang, Wei; Yao, Aiguo; Li, Yongbo; He, Wangyong; Fei, Dongdong

2018-06-01

In the present work, a down-to-the-hole electric hammer driven by linear motor is reported for drilling engineering. It differs from the common hydraulic or pneumatic hammers in that it can be applied to some special occasions without circulating medium due to its independence of the drilling fluid. The impact stress caused by the reciprocating motion between stator and rotor and the fatigue damage in key components of linear motor are analyzed by the ANSYS Workbench software and 3D model. Based on simulation results, the hammer's structure is optimized by using special sliding bearing, increasing the wall thickness of key and multilayer buffer gasket. Fatigue life and coefficient issues of the new structure are dramatically improved. However buffer gasket reduces the impactor's energy, different bumper structure effect on life improving and energy loss have also been elaborated.

Nonlinear elastic behavior of sub-critically damaged body armor panel

NASA Astrophysics Data System (ADS)

Fisher, Jason T.; Chimenti, D. E.

2012-05-01

A simple go/no-go test for body armor panels using pressure-sensitive, dye-indicator film (PSF) has been shown to be statistically effective in revealing subcritical damage to body armor panels. Previous measurements have shown that static indicator levels are accurately reproduced in dynamic loading events. Further impact tests on armor worn by a human resuscitation dummy using instrumented masses with an attached accelerometer and embedded force transducer have been performed and analyzed. New impact tests have shown a reliable correlation between PSF indication (as digitized images) and impact force for a wide range of impactor energies and masses. Numerical evaluation of digital PSF images is presented and correlated with impact parameters. Relationships between impactor mass and energy, and corresponding measured force are shown. We will also report on comparisons between ballistic testing performed on panels damaged under various impact conditions and tests performed on undamaged panels.

Geochemical Constraints on the Size of the Moon-Forming Giant Impact

NASA Astrophysics Data System (ADS)

Piet, Hélène; Badro, James; Gillet, Philippe

2017-12-01

Recent models involving the Moon-forming giant impact hypothesis have managed to reproduce the striking isotopic similarity between the two bodies, albeit using two extreme models: one involves a high-energy small impactor that makes the Moon out of Earth's proto-mantle; the other supposes a gigantic collision between two half-Earths creating the Earth-Moon system from both bodies. Here we modeled the geochemical influence of the giant impact on Earth's mantle and found that impactors larger than 15% of Earth mass result in mantles always violating the present-day concentrations of four refractory moderately siderophile trace elements (Ni, Co, Cr, and V). In the aftermath of the impact, our models cannot further discriminate between a fully and a partially molten bulk silicate Earth. Then, the preservation of primordial geochemical reservoirs predating the Moon remains the sole argument against a fully molten mantle after the Moon-forming impact.

Study of the penetration of a plate made of titanium alloy VT6 with a steel ball

NASA Astrophysics Data System (ADS)

Buzyurkin, A. E.

2018-03-01

The purpose of this work is the development and verification of mathematical relationships, adapted to the package of finite element analysis LS-DYNA and describing the deformation and destruction of a titanium plate in a high-speed collision. Using data from experiments on the interaction of a steel ball with a titanium plate made of VT6 alloy, verification of the available constants necessary for describing the behavior of the material using the Johnson-Cook relationships was performed, as well as verification of the parameters of the fracture model used in the numerical modeling of the collision process. An analysis of experimental data on the interaction of a spherical impactor with a plate showed that the data accepted for VT6 alloy in the first approximation for deformation hardening in the Johnson-Cook model give too high results on the residual velocities of the impactor when piercing the plate.

A Cyber-Astronaut's Final Moves

NASA Technical Reports Server (NTRS)

2005-01-01

This image shows how Deep Impact's impactor targeted comet Tempel 1 as the spacecraft made its final approach in the early morning hours of July 4, Eastern time. The autonomous navigation system on the probe was designed to make as many as three impactor targeting maneuvers, identified as ITMs in this picture, to correct its course to the comet.

The upper left dot indicates where the probe would have passed the comet's nucleus if no maneuvers were performed. The dot below the nucleus shows where the probe would have flown past the comet if only the first maneuver was made. The leftmost dot on the nucleus marks the spot where the probe would have crunched the comet if only the first two maneuvers had been performed. The lower dot on the nucleus indicates the vicinity where, once the third maneuver was performed, the probe met its final reward and collided with the comet.

Artist rendering of dust grains colliding at low speeds

NASA Technical Reports Server (NTRS)

2003-01-01

Clues to the formation of planets and planetary rings -- like Saturn's dazzling ring system -- may be found by studying how dust grains interact as they collide at low speeds. To study the question of low-speed dust collisions, NASA sponsored the COLLisions Into Dust Experiment (COLLIDE) at the University of Colorado. It was designed to spring-launch marble-size projectiles into trays of powder similar to space or lunar dust. COLLIDE-1 (1998) discovered that collisions below a certain energy threshold eject no material. COLLIDE-2 was designed to identify where the threshold is. In COLLIDE-2, scientists nudged small projectiles into dust beds and recorded how the dust splashed outward (video frame at top; artist's rendering at bottom). The slowest impactor ejected no material and stuck in the target. The faster impactors produced ejecta; some rebounded while others stuck in the target.

Characterization and first results of an ice nucleating particle measurement system based on counterflow virtual impactor technique

NASA Astrophysics Data System (ADS)

Schenk, L. P.; Mertes, S.; Kästner, U.; Frank, F.; Nillius, B.; Bundke, U.; Rose, D.; Schmidt, S.; Schneider, J.; Worringen, A.; Kandler, K.; Bukowiecki, N.; Ebert, M.; Curtius, J.; Stratmann, F.

2014-10-01

A specific instrument combination was developed to achieve a better microphysical and chemical characterization of atmospheric aerosol particles that have the potential to act as ice nucleating particles (INP). For this purpose a pumped counterflow virtual impactor system called IN-PCVI was set up and characterized to separate ice particles that had been activated on INP in the Fast Ice Nucleus Chamber (FINCH) from interstitial, non-activated particles. This coupled setup consisting of FINCH (ice particle activation and counting), IN-PCVI (INP separation and preparation), and further aerosol instrumentation (INP characterization) had been developed for the application in field experiments. The separated INP were characterized on-line with regard to their total number concentration, number size distribution and chemical composition, especially with the Aircraft-based Laser Ablation Aerosol Mass Spectrometer ALABAMA. Moreover, impactor samples for electron microscopy were taken. Due to the coupling the IN-PCVI had to be operated with different flow settings than known from literature, which required a further characterization of its cut-off-behavior. Taking the changed cut-off-behavior into account, the INP number concentration measured by the IN-PCVI system was in good agreement with the one detected by the FINCH optics for water saturation ratios up to 1.01 (ice saturation ratios between 1.21-1.34 and temperatures between -18 and -26 °C). First field results of INP properties are presented which were gained during the INUIT-JFJ/CLACE 2013 campaign at the high altitude research station Jungfraujoch in the Bernese Alps, Switzerland (3580 m a.s.l.).

Geochemical arguments for an Earth-like Moon-forming impactor.

PubMed

Dauphas, Nicolas; Burkhardt, Christoph; Warren, Paul H; Fang-Zhen, Teng

2014-09-13

Geochemical evidence suggests that the material accreted by the Earth did not change in nature during Earth's accretion, presumably because the inner protoplanetary disc had uniform isotopic composition similar to enstatite chondrites, aubrites and ungrouped achondrite NWA 5363/5400. Enstatite meteorites and the Earth were derived from the same nebular reservoir but diverged in their chemical evolutions, so no chondrite sample in meteorite collections is representative of the Earth's building blocks. The similarity in isotopic composition (Δ(17)O, ε(50)Ti and ε(54)Cr) between lunar and terrestrial rocks is explained by the fact that the Moon-forming impactor came from the same region of the disc as other Earth-forming embryos, and therefore was similar in isotopic composition to the Earth. The heavy δ(30)Si values of the silicate Earth and the Moon relative to known chondrites may be due to fractionation in the solar nebula/protoplanetary disc rather than partitioning of silicon in Earth's core. An inversion method is presented to calculate the Hf/W ratios and ε(182)W values of the proto-Earth and impactor mantles for a given Moon-forming impact scenario. The similarity in tungsten isotopic composition between lunar and terrestrial rocks is a coincidence that can be explained in a canonical giant impact scenario if an early formed embryo (two-stage model age of 10-20 Myr) collided with the proto-Earth formed over a more protracted accretion history (two-stage model age of 30-40 Myr). © 2014 The Author(s) Published by the Royal Society. All rights reserved.

The Physics of Protoplanetesimal Dust Agglomerates. IX. Mechanical Properties of Dust Aggregates Probed by a Solid-projectile Impact

NASA Astrophysics Data System (ADS)

Katsuragi, Hiroaki; Blum, Jürgen

2017-12-01

Dynamic characterization of mechanical properties of dust aggregates has been one of the most important problems to quantitatively discuss the dust growth in protoplanetary disks. We experimentally investigate the dynamic properties of dust aggregates by low-speed (≤slant 3.2 m s-1) impacts of solid projectiles. Spherical impactors made of glass, steel, or lead are dropped onto a dust aggregate with a packing fraction of ϕ = 0.35 under vacuum conditions. The impact results in cratering or fragmentation of the dust aggregate, depending on the impact energy. The crater shape can be approximated by a spherical segment and no ejecta are observed. To understand the underlying physics of impacts into dust aggregates, the motion of the solid projectile is acquired by a high-speed camera. Using the obtained position data of the impactor, we analyze the drag-force law and dynamic pressure induced by the impact. We find that there are two characteristic strengths. One is defined by the ratio between impact energy and crater volume and is ≃120 kPa. The other strength indicates the fragmentation threshold of dynamic pressure and is ≃10 kPa. The former characterizes the apparent plastic deformation and is consistent with the drag force responsible for impactor deceleration. The latter corresponds to the dynamic tensile strength to create cracks. Using these results, a simple model for the compaction and fragmentation threshold of dust aggregates is proposed. In addition, the comparison of drag-force laws for dust aggregates and loose granular matter reveals the similarities and differences between the two materials.

Effect of impact stress on microbial recovery on an agar surface.

PubMed Central

Stewart, S L; Grinshpun, S A; Willeke, K; Terzieva, S; Ulevicius, V; Donnelly, J

1995-01-01

Microbial stress due to the impaction of microorganisms onto an agar collection surface was studied experimentally. The relative recovery rates of aerosolized Pseudomonas fluorescens and Micrococcus luteus were determined as a function of the impaction velocity by using a moving agar slide impactor operating over a flow rate range from 3.8 to 40 liters/min yielding impaction velocities from 24 to 250 m/s. As a reference, the sixth stage of the Andersen Six-Stage Viable Particle Sizing Sampler was used at its operating flow rate of 28.3 liters/min (24 m/s). At a collection efficiency of close to 100% for the agar slide impactor, an increase in sampling flow rate and, therefore, in impaction velocity produced a significant decline in the percentage of microorganisms recovered. Conversely, when the collection efficiency was less than 100%, greater recovery and lower injury rates occurred. The highest relative rate of recovery (approximately 51% for P. fluorescens and approximately 62% for M. luteus) was obtained on the complete (Trypticase soy agar) medium at 40 and 24 m/s (6.4 and 3.8 liters/min), respectively. M. luteus demonstrated less damage than P. fluorescens, suggesting the hardy nature of the gram-positive strain versus that of the gram-negative microorganism. Comparison of results from the agar slide and Andersen impactors at the same sampling velocity showed that recovery and injury due to collection depends not only on the magnitude of the impaction velocity but also on the degree to which the microorganisms may be embedded in the collection medium.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7747946

Efficiency of planetesimal ablation in giant planetary envelopes

NASA Astrophysics Data System (ADS)

Pinhas, Arazi; Madhusudhan, Nikku; Clarke, Cathie

2016-12-01

Observations of exoplanetary spectra are leading to unprecedented constraints on their atmospheric elemental abundances, particularly O/H, C/H, and C/O ratios. Recent studies suggest that elemental ratios could provide important constraints on formation and migration mechanisms of giant exoplanets. A fundamental assumption in such studies is that the chemical composition of the planetary envelope represents the sum-total of compositions of the accreted gas and solids during the formation history of the planet. We investigate the efficiency with which accreted planetesimals ablate in a giant planetary envelope thereby contributing to its composition rather than sinking to the core. From considerations of aerodynamic drag causing `frictional ablation' and the envelope temperature structure causing `thermal ablation', we compute mass ablations for impacting planetesimals of radii 30 m to 1 km for different compositions (ice to iron) and a wide range of velocities and impact angles, assuming spherical symmetry. Icy impactors are fully ablated in the outer envelope for a wide range of parameters. Even for Fe impactors substantial ablation occurs in the envelope for a wide range of sizes and velocities. For example, iron impactors of sizes below ˜0.5 km and velocities above ˜30 km s-1 are found to ablate by ˜60-80 per cent within the outer envelope at pressures below 103 bar due to frictional ablation alone. For deeper pressures (˜107 bar), substantial ablation happens over a wider range of parameters. Therefore, our exploratory study suggests that atmospheric abundances of volatile elements in giant planets reflect their accretion history during formation.

The Deflector Selector: A Machine Learning Framework for Prioritizing Deflection Technology Development

NASA Astrophysics Data System (ADS)

Nesvold, E. R.; Erasmus, N.; Greenberg, A.; van Heerden, E.; Galache, J. L.; Dahlstrom, E.; Marchis, F.

2017-02-01

We present a machine learning model that can predict which asteroid deflection technology would be most effective, given the likely population of impactors. Our model can help policy and funding agencies prioritize technology development.

Heat Map of Jupiter Impact

NASA Image and Video Library

2011-01-26

This infrared image, showing thermal radiation at a wavelength of 9.7 microns, was obtained by the Gemini North Telescope in Hawaii. The bright white and yellow features at bottom are the aftermath of an impactor hitting Jupiter on July 19, 2009.

Separation Anxiety Over for Deep Impact

NASA Image and Video Library

2005-07-04

This image of NASA Deep Impact impactor probe was taken by the mission mother ship, or flyby spacecraft, after the two separated at 11:07 p.m. Pacific time, July 2 2:07 a.m. Eastern time, July 3, 2005.

Chemical composition, mixing state, size and morphology of Ice nucleating particles at the Jungfraujoch research station, Switzerland

NASA Astrophysics Data System (ADS)

Ebert, Martin; Worringen, Annette; Kandler, Konrad; Weinbruch, Stephan; Schenk, Ludwig; Mertes, Stephan; Schmidt, Susan; Schneider, Johannes; Frank, Fabian; Nilius, Björn; Danielczok, Anja; Bingemer, Heinz

2014-05-01

An intense field campaign from the Ice Nuclei Research Unit (INUIT) was performed in January and February of 2013 at the High-Alpine Research Station Jungfraujoch (3580 m a.s.l., Switzerland). Main goal was the assessment of microphysical and chemical properties of free-tropospheric ice-nucelating particles. The ice-nucleating particles were discriminated from the total aerosol with the 'Fast Ice Nucleation CHamber' (FINCH; University Frankfurt) and the 'Ice-Selective Inlet' (ISI, Paul Scherer Institute) followed by a pumped counter-stream virtual impactor. The separated ice-nucleating particles were then collected with a nozzle-type impactor. With the 'FRankfurt Ice nuclei Deposition freezinG Experiment' (FRIDGE), aerosol particles are sampled on a silicon wafer, which is than exposed to ice-activating conditions in a static diffusion chamber. The locations of the growing ice crystals are recorded for later analysis. Finally, with the ICE Counter-stream Virtual Impactor (ICE-CVI) atmospheric ice crystals are separated from the total aerosol and their water content is evaporated to retain the ice residual particles, which are then collected also by impactor sampling. All samples were analyzed in a high-resolution scanning electron microscope. By this method, for each particle its size, morphology, mixing-state and chemical composition is obtained. In total approximately 1700 ice nucleating particles were analyzed. Based on their chemical composition, the particles were classified into seven groups: silicates, metal oxides, Ca-rich particles, (aged) sea-salt, soot, sulphates and carbonaceous matter. Sea-salt is considered as artifact and is not regarded as ice nuclei here. The most frequent ice nucleating particles/ice residuals at the Jungfraujoch station are silicates > carbonaceous particles > metal oxides. Calcium-rich particles and soot play a minor role. Similar results are obtained by quasi-parallel measurements with an online single particle laser ablation mass spectrometer (ALABAMA). All the tested techniques for measuring ice nucleating particles perform similar from a chemical point of view within the range of their uncertainties and low counting statistics due to the low particle concentrations in free-tropospheric air. Thus, for the first time most of the existing ice nucleation measurement techniques could be compared side by side under real-world atmospheric conditions. Acknowledgment This project is founded by DFG project INUIT (FOR 1525)

Concussion in professional football: helmet testing to assess impact performance--part 11.

PubMed

Pellman, Elliot J; Viano, David C; Withnall, Chris; Shewchenko, Nick; Bir, Cynthia A; Halstead, P David

2006-01-01

National Football League (NFL) concussions occur at an impact velocity of 9.3 +/- 1.9 m/s (20.8 +/- 4.2 mph) oblique on the facemask, side, and back of the helmet. There is a need for new testing to evaluate helmet performance for impacts causing concussion. This study provides background on new testing methods that form a basis for supplemental National Operating Committee on Standards for Athletic Equipment (NOCSAE) helmet standards. First, pendulum impacts were used to simulate 7.4 and 9.3 m/s impacts causing concussion in NFL players. An instrumented Hybrid III head was helmeted and supported on the neck, which was fixed to a sliding table for frontal and lateral impacts. Second, a linear pneumatic impactor was used to evaluate helmets at 9.3 m/s and an elite impact condition at 11.2 m/s. The upper torso of the Hybrid III dummy was used. It allowed interactions with shoulder pads and other equipment. The severity of the head responses was measured by a severity index, translational and rotational acceleration, and other biomechanical responses. High-speed videos of the helmet kinematics were also recorded. The tests were evaluated for their similarity to conditions causing NFL concussions. Finally, a new linear impactor was developed for use by NOCSAE. The pendulum test closely simulated the conditions causing concussion in NFL players. Newer helmet designs and padding reduced the risk of concussion in 7.4 and 9.3 m/s impacts oblique on the facemask and lateral on the helmet shell. The linear impactor provided a broader speed range for helmet testing and more interactions with safety equipment. NOCSAE has prepared a draft supplemental standard for the 7.4 and 9.3 m/s impacts using a newly designed pneumatic impactor. No helmet designs currently address the elite impact condition at 11.2 m/s, as padding bottoms out and head responses dramatically increase. The proposed NOCSAE standard is the first to address helmet performance in reducing concussion risks in football. Helmet performance has improved with thicker padding and fuller coverage by the shell. However, there remains a challenge for innovative designs that reduce risks in the 11.2 m/s elite impact condition.

BILLIARDS: A Demonstration Mission for Hundred-Meter Class Near-Earth Asteroid Disruption

NASA Technical Reports Server (NTRS)

Marcus, Matthew; Sloane, Joshua; Ortiz, Oliver; Barbee, Brent William

2015-01-01

Collisions from near-Earth asteroids (NEAs) have the potential to cause widespread harm to life on Earth. The hypervelocity nature of these collisions means that a relatively small asteroid (about a quartermile in diameter) could cause a global disaster. Proposed strategies for deflecting or disrupting such a threatening asteroid include detonation of a nuclear explosive device (NED) in close proximity to the asteroid, as well as intercepting the asteroid with a hypervelocity kinetic impactor. NEDs allow for the delivery of large amounts of energy to a NEA for a given mass launched from the Earth, but have not yet been developed or tested for use in deep space. They also present safety and political complications, and therefore may only be used when absolutely necessary. Kinetic impactors require a relatively simple spacecraft compared to NEDs, but also deliver a much lower energy for a given launch mass. To date, no demonstration mission has been conducted for either case, and such a demonstration mission must be conducted prior to the need to utilize them during an actual scenario to ensure that an established, proven system is available for planetary defense when the need arises. One method that has been proposed to deliver a kinetic impactor with impact energy approaching that of an NED is the "billiard-ball" approach. This approach would involve capturing an asteroid approximately ten meters in diameter with a relatively small spacecraft (compared to the launch mass of an equivalent direct kinetic impactor), and redirecting it into the path of an Earth-threatening asteroid. This would cause an impact which would disrupt the Earth-threatening asteroid or deflect it from its Earth-crossing trajectory. The BILLIARDS Project seeks to perform a demonstration of this mission concept in order to establish a protocol that can be used in the event of an impending Earth/asteroid collision. In order to accomplish this objective, the mission must (1) rendezvous with a small (less than 10m), NEA (hereinafter "Alpha"), (2) maneuver Alpha to a collision with a approx. 100 m NEA (hereinafter "Beta"), and (3) produce a detectable deflection or disruption of Beta. In addition to these primary objectives, the BILLIARDS project will contribute to the scientific understanding of the physical properties and collision dynamics of asteroids, and provide opportunities for international collaboration.

Lateral and posterior dynamic bending of the mid-shaft femur: fracture risk curves for the adult population.

PubMed

Kennedy, Eric A; Hurst, William J; Stitzel, Joel D; Cormier, Joseph M; Hansen, Gail A; Smith, Eric P; Duma, Stefan M

2004-11-01

The purpose of this study was to develop injury risk functions for dynamic bending of the human femur in the lateral-to-medial and posterior-to-anterior loading directions. A total of 45 experiments were performed on human cadaver femurs using a dynamic three-point drop test setup. An impactor of 9.8 kg was dropped from 2.2 m for an impact velocity of 5 m/s. Five-axis load cells measured the impactor and support loads, while an in situ strain gage measured the failure strain and subsequent strain rate. All 45 tests resulted in mid-shaft femur fractures with comminuted wedge and oblique fractures as the most common fracture patterns. In the lateral-to-medial bending tests the reaction loads were 4180 +/- 764 N, and the impactor loads were 4780 +/- 792 N. In the posterior-to-anterior bending tests the reaction loads were 3780 +/- 930 N, and the impactor loads were 4310 +/- 1040 N. The difference between the sum of the reaction forces and the applied load is due to inertial effects. The reaction loads were used to estimate the mid-shaft bending moments at failure since there was insufficient data to include the inertial effects in the calculations. The resulting moments are conservative estimates (lower bounds) of the mid-shaft bending moments at failure and are appropriate for use in the assessment of knee restraints and pedestrian impacts with ATD measurements. Regression analysis was used to identify significant parameters, and parametric survival analysis was used to estimate risk functions. Femur cross-sectional area, area moment of inertia (I), maximum distance to the neutral axis (c), I/c, occupant gender, and occupant mass are shown to be significant predictors of fracture tolerance, while no significant difference is shown for loading direction, bone mineral density, leg aspect and age. Risk functions are presented for femur cross-sectional area and I/c as they offer the highest correlation to peak bending moment. The risk function that utilizes the most highly correlated (R2 = 0.82) and significant (p = 0.0001) variable, cross-sectional area, predicts a 50 percent risk of femur fracture of 240 Nm, 395 Nm, and 562 Nm for equivalent cross-sectional area of the 5(th) percentile female, 50(th) percentile male, and 95(th) percentile male respectively.

Late Veneer collisions and their impact on the evolution of Venus (PS Division Outstanding ECS Award Lecture)

NASA Astrophysics Data System (ADS)

Gillmann, Cedric; Golabek, Gregor; Tackley, Paul; Raymond, Sean

2017-04-01

During the end of the accretion, the so-called Late Veneer phase, while the bulk of the mass of terrestrial planets is already in place, a substantial number of large collisions can still occur. Those impacts are thought to be responsible for the repartition of the Highly Siderophile Elements. They are also susceptible to have a strong effect on volatile repartition and mantle convection. We study how Late Veneer impacts modify the evolution of Venus and its atmosphere, using a coupled numerical simulation. We focus on volatile exchanges and their effects on surface conditions. Mantle dynamics, volcanism and degassing processes lead to an input of gases in the atmosphere and are modeled using the StagYY mantle convection code. Volatile losses are estimated through atmospheric escape modeling. It involves two different aspects: hydrodynamic escape (0-500 Myr) and non-thermal escape. Hydrodynamic escape is massive but occurs only when the solar energy input is strong. Post 4 Ga escape from non-thermal processes is comparatively low but long-lived. The resulting state of the atmosphere is used to the calculate greenhouse effect and surface temperature, through a one-dimensional gray radiative-convective model. Large impacts are capable of contributing to (i) atmospheric escape, (ii) volatile replenishment and (iii) energy transfer to the mantle. We test various impactor compositions, impact parameters (velocity, location, size, and timing) and eroding power. Scenarios we tested are adapted from numerical stochastic simulations (Raymond et al., 2013). Impactor sizes are dominated by large bodies (R>500 km). Erosion of the atmosphere by a few large impacts appears limited. Swarms of smaller more mass-effective impactors seem required for this effect to be significant. Large impactors have two main effects on the atmosphere. They can (i) create a large input of volatile from the melting they cause during the impact and through the volatiles they carry. This leads to an increase in atmosphere density and surface temperatures. However, early impacts can also (ii) deplete the mantle of Venus and (assuming strong early escape) ultimately remove volatiles from the system, leading to lower late degassing and lower surface temperatures. The competition between those effects depends on the time of the impact, which directly governs the strength of atmospheric losses.

Sensitivity of head and cervical spine injury measures to impact factors relevant to rollover crashes.

PubMed

Mattos, G A; Mcintosh, A S; Grzebieta, R H; Yoganandan, N; Pintar, F A

2015-01-01

Serious head and cervical spine injuries have been shown to occur mostly independent of one another in pure rollover crashes. In an attempt to define a dynamic rollover crash test protocol that can replicate serious injuries to the head and cervical spine, it is important to understand the conditions that are likely to produce serious injuries to these 2 body regions. The objective of this research is to analyze the effect that impact factors relevant to a rollover crash have on the injury metrics of the head and cervical spine, with a specific interest in the differentiation between independent injuries and those that are predicted to occur concomitantly. A series of head impacts was simulated using a detailed finite element model of the human body, the Total HUman Model for Safety (THUMS), in which the impactor velocity, displacement, and direction were varied. The performance of the model was assessed against available experimental tests performed under comparable conditions. Indirect, kinematic-based, and direct, tissue-level, injury metrics were used to assess the likelihood of serious injuries to the head and cervical spine. The performance of the THUMS head and spine in reconstructed experimental impacts compared well to reported values. All impact factors were significantly associated with injury measures for both the head and cervical spine. Increases in impact velocity and displacement resulted in increases in nearly all injury measures, whereas impactor orientation had opposite effects on brain and cervical spine injury metrics. The greatest cervical spine injury measures were recorded in an impact with a 15° anterior orientation. The greatest brain injury measures occurred when the impactor was at its maximum (45°) angle. The overall kinetic and kinematic response of the THUMS head and cervical spine in reconstructed experiment conditions compare well with reported values, although the occurrence of fractures was overpredicted. The trends in predicted head and cervical spine injury measures were analyzed for 90 simulated impact conditions. Impactor orientation was the only factor that could potentially explain the isolated nature of serious head and spine injuries under rollover crash conditions. The opposing trends of injury measures for the brain and cervical spine indicate that it is unlikely to reproduce the injuries simultaneously in a dynamic rollover test.

Dissipation of Turbulence in the Solar Wind

NASA Technical Reports Server (NTRS)

Goldstein, Melvyn L.

2010-01-01

I will describe the first three-dimensional (3-D) dispersion relations and wavenumber spectra of magnetic turbulence in the solar wind at sub-proton scales. The analysis takes advantage of the short separations of the Cluster spacecraft (d/sim approx.200 km) to apply the {it k}-filtering technique to the frequency range where the transition to sub-proton scales occurs. The dispersion diagrams show unambiguously that the cascade is carried by highly oblique Kinetic Alfven Wave with \\omega\\leq 0.1\\omega_{ci} in the plasma rest frame down to k_\\perp\\rho_i \\sim 2. The wavenumber spectra in the direction perpendicular to the mean magnetic field consists of two ranges of scales separated by a breakpoint in the interval [0.4,1] k_\\perp \\rho_i. Above the breakpoint, the spectra follow the Kolmogorov scaling k_\\perp^{-1.7}, consistent with existing theoretical predictions. Below the breakpoint, the spectra steepen to \\sim k_\\perp^{-4.5}. We conjecture that the turbulence undergoes a {\\it transition-range}, where part of energy is dissipated into proton heating via Landau damping, and the remaining energy cascades down to electron scales where electron Landau damping may predominate.

Planetary Accretion as Informed by Meteoritic Samples of Early Solar System Planetesimals

NASA Astrophysics Data System (ADS)

Kring, D. A.

2017-08-01

Meteoritic impact melts and impact breccias contain information about the timing and sizes of collisions, which, when augmented with hints about impactor compositions, provide clues about mixing and the dynamical situation in the early solar system.

SENSITIVITY ANALYSIS OF THE USEPA WINS PM 2.5 SEPARATOR

EPA Science Inventory

Factors affecting the performance of the US EPA WINS PM2.5 separator have been systematically evaluated. In conjunction with the separator's laboratory calibrated penetration curve, analysis of the governing equation that describes conventional impactor performance was used to ...

Factors influencing microbial colonies in the air of operating rooms.

PubMed

Fu Shaw, Ling; Chen, Ian Horng; Chen, Chii Shya; Wu, Hui Hsin; Lai, Li Shing; Chen, Yin Yin; Wang, Fu Der

2018-01-02

The operating room (OR) of the hospital is a special unit that requires a relatively clean environment. The microbial concentration of an indoor OR extrinsically influences surgical site infection rates. The aim of this study was to use active sampling methods to assess microbial colony counts in working ORs and to determine the factors affecting air contamination in a tertiary referral medical center. This study was conducted in 28 operating rooms located in a 3000-bed medical center in northern Taiwan. The microbiologic air counts were measured using an impactor air sampler from May to August 2015. Information about the procedure-related operative characteristics and surgical environment (environmental- and personnel-related factors) characteristics was collected. A total of 250 air samples were collected during surgical procedures. The overall mean number of bacterial colonies in the ORs was 78 ± 47 cfu/m 3 . The mean number of colonies was the highest for transplant surgery (123 ± 60 cfu/m 3 ), followed by pediatric surgery (115 ± 30.3 cfu/m 3 ). A total of 25 samples (10%) contained pathogens; Coagulase-negative staphylococcus (n = 12, 4.8%) was the most common pathogen. After controlling for potentially confounding factors by a multiple regression analysis, the surgical stage had the significantly highest correlation with bacterial counts (r = 0.346, p < 0.001). Otherwise, independent factors influencing bacterial counts were the type of surgery (29.85 cfu/m 3 , 95% CI 1.28-58.42, p = 0.041), site of procedure (20.19 cfu/m 3 , 95% CI 8.24-32.14, p = 0.001), number of indoor staff (4.93 cfu/m 3 , 95% CI 1.47-8.38, p = 0.005), surgical staging (36.5 cfu/m 3 , 95% CI 24.76-48.25, p < 0.001), and indoor air temperature (9.4 cfu/m 3 , 95% CI 1.61-17.18, p = 0.018). Under the well-controlled ventilation system, the mean microbial colony counts obtained by active sampling in different working ORs were low. The number of personnel and their activities critically influence the microbe concentration in the air of the OR. We suggest that ORs doing complex surgeries with more surgical personnel present should increase the frequency of air exchanges. A well-controlled ventilation system and infection control procedures related to environmental and surgical procedures are of paramount importance for reducing microbial colonies in the air.

A young Moon-forming giant impact at 70-110 million years accompanied by late-stage mixing, core formation and degassing of the Earth.

PubMed

Halliday, Alex N

2008-11-28

New W isotope data for lunar metals demonstrate that the Moon formed late in isotopic equilibrium with the bulk silicate Earth (BSE). On this basis, lunar Sr isotope data are used to define the former composition of the Earth and hence the Rb-Sr age of the Moon, which is 4.48+/-0.02Ga, or 70-110Ma (million years) after the start of the Solar System. This age is significantly later than had been deduced from W isotopes based on model assumptions or isotopic effects now known to be cosmogenic. The Sr age is in excellent agreement with earlier estimates based on the time of lunar Pb loss and the age of the early lunar crust (4.46+/-0.04Ga). Similar ages for the BSE are recorded by xenon and lead-lead, providing evidence of catastrophic terrestrial degassing, atmospheric blow-off and significant late core formation accompanying the ca 100Ma giant impact. Agreement between the age of the Moon based on the Earth's Rb/Sr and the lead-lead age of the Moon is consistent with no major losses of moderately volatile elements from the Earth during the giant impact. The W isotopic composition of the BSE can be explained by end member models of (i) gradual accretion with a mean life of roughly 35Ma or (ii) rapid growth with a mean life of roughly 10Ma, followed by a significant hiatus prior to the giant impact. The former assumes that approximately 60 per cent of the incoming metal from impactors is added directly to the core during accretion. The latter includes complete mixing of all the impactor material into the BSE during accretion. The identical W isotopic composition of the Moon and the BSE limits the amount of material that can be added as a late veneer to the Earth after the giant impact to less than 0.3+/-0.3 per cent of ordinary chondrite or less than 0.5+/-0.6 per cent CI carbonaceous chondrite based on their known W isotopic compositions. Neither of these on their own is sufficient to explain the inventories of both refractory siderophiles such as platinum group elements and rhenium, and volatiles such as sulphur, carbon and water.

Exposure and Emissions Monitoring during Carbon Nanofiber Production—Part I: Elemental Carbon and Iron–Soot Aerosols

PubMed Central

Birch, M. Eileen; Ku, Bon-Ki; Evans, Douglas E.; Ruda-Eberenz, Toni A.

2015-01-01

Production of carbon nanofibers and nanotubes (CNFs/CNTs) and their composite products is increasing globally. High volume production may increase the exposure risks for workers who handle these materials. Though health effects data for CNFs/CNTs are limited, some studies raise serious health concerns. Given the uncertainty about their potential hazards, there is an immediate need for toxicity data and field studies to assess exposure to CNFs/CNTs. An extensive study was conducted at a facility that manufactures and processes CNFs. Filter, sorbent, cascade impactor, bulk, and microscopy samples, combined with direct-reading instruments, provided complementary information on air contaminants. Samples were analyzed for organic carbon (OC) and elemental carbon (EC), metals, and polycyclic aromatic hydrocarbons (PAHs), with EC as a measure of CNFs. Transmission electron microscopy with energy-dispersive X-ray spectroscopy also was applied. Fine/ultrafine iron-rich soot, PAHs, and carbon monoxide were production byproducts. Direct-reading instrument results were reported previously [Evans DE et al. (Aerosol monitoring during carbon nanofiber production: mobile direct-reading sampling. Ann Occup Hyg 2010;54:514–31.)] Results for time-integrated samples are reported as companion papers in this Issue. OC and EC, metals, and microscopy results are reported here, in Part I, while results for PAHs are reported in Part II [Birch ME. (Exposure and Emissions Monitoring during Carbon Nanofiber Production—Part II: Polycyclic Aromatic Hydrocarbons. Ann. Occup. Hyg 2011; 55: 1037–47.)]. Respirable EC area concentrations inside the facility were about 6–68 times higher than outdoors, while personal breathing zone samples were up to 170 times higher. PMID:21965464

Size-resolved chemical composition of aerosol emitted by Erebus volcano, Antarctica

NASA Astrophysics Data System (ADS)

Ilyinskaya, E.; Oppenheimer, C.; Mather, T. A.; Martin, R. S.; Kyle, P. R.

2010-03-01

Persistent, open-vent degassing of Erebus volcano, Antarctica, is a significant point source of gases and aerosol to the austral polar troposphere. We report here on the chemical composition and size distribution of the Erebus aerosol, focusing on the water-soluble fraction. The aerosol was sampled at the rim of the active crater using a cascade impactor, which collected and sized particles in 14 size bins from >10 to 0.01 μm. The soluble fraction of the Erebus aerosol is distinct from other volcanic sources in several respects. It is dominated by chloride-bearing particles (over 30% of total mass) and has an unusually high Cl-/SO42- molar ratio of 3.5. Coarse particles contribute little to the total mass of the soluble fraction. Elevated concentrations of F-, Cl-, Br-, and SO42- are found in a narrow particle size fraction of 0.1-0.25 μm. The detection of particulate Br- reinforces our understanding of the potential for quiescent volcanic emissions to deplete tropospheric ozone. The small aerosol size reflects the low atmospheric temperature and humidity, which inhibit particle growth. Halide-alkali metal salts (Na, K)(Cl, F) appear to be the most abundant species in the aerosol. The concentration of Pb is high compared to other volcanoes; its exsolution may be promoted by the high abundance of halogens in Erebus magma. Despite the previously reported high NOx content in the plume, we did not detect significant quantities of nitrate in the near-vent aerosol. Our findings emphasize the potential regional significance of emissions from Erebus for understanding the Antarctic atmospheric composition and glaciochemical records.

Face Masks and Cough Etiquette Reduce the Cough Aerosol Concentration of Pseudomonas aeruginosa in People with Cystic Fibrosis.

PubMed

Wood, Michelle E; Stockwell, Rebecca E; Johnson, Graham R; Ramsay, Kay A; Sherrard, Laura J; Jabbour, Nassib; Ballard, Emma; O'Rourke, Peter; Kidd, Timothy J; Wainwright, Claire E; Knibbs, Luke D; Sly, Peter D; Morawska, Lidia; Bell, Scott C

2018-02-01

People with cystic fibrosis (CF) generate Pseudomonas aeruginosa in droplet nuclei during coughing. The use of surgical masks has been recommended in healthcare settings to minimize pathogen transmission between patients with CF. To determine if face masks and cough etiquette reduce viable P. aeruginosa aerosolized during coughing. Twenty-five adults with CF and chronic P. aeruginosa infection were recruited. Participants performed six talking and coughing maneuvers, with or without face masks (surgical and N95) and hand covering the mouth when coughing (cough etiquette) in an aerosol-sampling device. An Andersen Cascade Impactor was used to sample the aerosol at 2 meters from each participant. Quantitative sputum and aerosol bacterial cultures were performed, and participants rated the mask comfort levels during the cough maneuvers. During uncovered coughing (reference maneuver), 19 of 25 (76%) participants produced aerosols containing P. aeruginosa, with a positive correlation found between sputum P. aeruginosa concentration (measured as cfu/ml) and aerosol P. aeruginosa colony-forming units. There was a reduction in aerosol P. aeruginosa load during coughing with a surgical mask, coughing with an N95 mask, and cough etiquette compared with uncovered coughing (P < 0.001). A similar reduction in total colony-forming units was observed for both masks during coughing; yet, participants rated the surgical masks as more comfortable (P = 0.013). Cough etiquette provided approximately half the reduction of viable aerosols of the mask interventions during voluntary coughing. Talking was a low viable aerosol-producing activity. Face masks reduce cough-generated P. aeruginosa aerosols, with the surgical mask providing enhanced comfort. Cough etiquette was less effective at reducing viable aerosols.

Aerosol sampling system for collection of Capstone depleted uranium particles in a high-energy environment.

PubMed

Holmes, Thomas D; Guilmette, Raymond A; Cheng, Yung Sung; Parkhurst, Mary Ann; Hoover, Mark D

2009-03-01

The Capstone Depleted Uranium (DU) Aerosol Study was undertaken to obtain aerosol samples resulting from a large-caliber DU penetrator striking an Abrams or Bradley test vehicle. The sampling strategy was designed to (1) optimize the performance of the samplers and maintain their integrity in the extreme environment created during perforation of an armored vehicle by a DU penetrator, (2) collect aerosols as a function of time post perforation, and (3) obtain size-classified samples for analysis of chemical composition, particle morphology, and solubility in lung fluid. This paper describes the experimental setup and sampling methodologies used to achieve these objectives. Custom-designed arrays of sampling heads were secured to the inside of the target in locations approximating the breathing zones of the crew locations in the test vehicles. Each array was designed to support nine filter cassettes and nine cascade impactors mounted with quick-disconnect fittings. Shielding and sampler placement strategies were used to minimize sampler loss caused by the penetrator impact and the resulting fragments of eroded penetrator and perforated armor. A cyclone train was used to collect larger quantities of DU aerosol for measurement of chemical composition and solubility. A moving filter sample was used to obtain semicontinuous samples for DU concentration determination. Control for the air samplers was provided by five remotely located valve control and pressure monitoring units located inside and around the test vehicle. These units were connected to a computer interface chassis and controlled using a customized LabVIEW engineering computer control program. The aerosol sampling arrays and control systems for the Capstone study provided the needed aerosol samples for physicochemical analysis, and the resultant data were used for risk assessment of exposure to DU aerosol.

Aerosol Sampling System for Collection of Capstone Depleted Uranium Particles in a High-Energy Environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holmes, Thomas D.; Guilmette, Raymond A.; Cheng, Yung-Sung

2009-03-01

The Capstone Depleted Uranium Aerosol Study was undertaken to obtain aerosol samples resulting from a kinetic-energy cartridge with a large-caliber depleted uranium (DU) penetrator striking an Abrams or Bradley test vehicle. The sampling strategy was designed to (1) optimize the performance of the samplers and maintain their integrity in the extreme environment created during perforation of an armored vehicle by a DU penetrator, (2) collect aerosols as a function of time post-impact, and (3) obtain size-classified samples for analysis of chemical composition, particle morphology, and solubility in lung fluid. This paper describes the experimental setup and sampling methodologies used tomore » achieve these objectives. Custom-designed arrays of sampling heads were secured to the inside of the target in locations approximating the breathing zones of the vehicle commander, loader, gunner, and driver. Each array was designed to support nine filter cassettes and nine cascade impactors mounted with quick-disconnect fittings. Shielding and sampler placement strategies were used to minimize sampler loss caused by the penetrator impact and the resulting fragments of eroded penetrator and perforated armor. A cyclone train was used to collect larger quantities of DU aerosol for chemical composition and solubility. A moving filter sample was used to obtain semicontinuous samples for depleted uranium concentration determination. Control for the air samplers was provided by five remotely located valve control and pressure monitoring units located inside and around the test vehicle. These units were connected to a computer interface chassis and controlled using a customized LabVIEW engineering computer control program. The aerosol sampling arrays and control systems for the Capstone study provided the needed aerosol samples for physicochemical analysis, and the resultant data were used for risk assessment of exposure to DU aerosol.« less

Nano-liposomal dry powder inhaler of tacrolimus: preparation, characterization, and pulmonary pharmacokinetics.

PubMed

Chougule, Mahavir; Padhi, Bijay; Misra, Ambikanandan

2007-01-01

The studies were undertaken to evaluate feasibility of pulmonary delivery of liposomaly encapsulated tacrolimus dry powder inhaler for prolonged drug retention in lungs as rescue therapy to prevent refractory rejection of lungs after transplantation. Tacrolimus encapsulated liposomes were prepared by thin film evaporation technique and liposomal dispersion was passed through high pressure homogenizer. Tacrolimus nano-liposomes (NLs) were separated by centrifugation and characterized. NLs were dispersed in phosphate buffer saline (PBS) pH 7.4 containing different additives like lactose, sucrose, and trehalose, and L-leucine as antiadherent. The dispersion was spray dried and spray dried powders were characterized. In vitro and in vivo pulmonary deposition was performed using Andersen Cascade Impactor and intratracheal instillation in rats respectively. NLs were found to have average size of 140 nm, 96% +/- 1.5% drug entrapment, and zeta potential of 1.107 mV. Trehalose based formulation was found to have low density, good flowability, particle size of 9.46 +/- 0.8 microm, maximum fine particle fraction (FPF) of 71.1 +/- 2.5%, mean mass aerodynamic diameter (MMAD) 2.2 +/- 0.1 microm, and geometric standard deviation (GSD) 1.7 +/- 0.2. Developed formulations were found to have in vitro prolonged drug release up to 18 hours, following Higuchi's Controlled Release model. In vivo studies revealed maximal residence of tacrolimus within lungs of 24 hours, suggesting slow clearance from the lungs. The investigation provides a practical approach for direct delivery of tacrolimus encapsulated in NLs for controlled and prolonged retention at the site of action. It may play a promising role as rescue therapy in reducing the risk of acute rejection and chronic rejection.

The effects of excipients and particle engineering on the biophysical stability and aerosol performance of parathyroid hormone (1-34) prepared as a dry powder for inhalation.

PubMed

Shoyele, Sunday A; Sivadas, Neeraj; Cryan, Sally-Ann

2011-03-01

Pulmonary delivery of therapeutic peptides and proteins has many advantages including high relative bioavailability, rapid systemic absorption and onset of action and a non-invasive mode of administration which improves patient compliance. In this study, we investigated the effect of spray-drying (SD) and spray freeze-drying processes on the stability and aerosol performance of parathyroid hormone (PTH) (1-34) microparticles. In this study, the stabilisation effect of trehalose (a non-reducing sugar) and Brij 97 (a non-ionic surfactant) on spray-dried PTH particles was assessed using analytical techniques including circular dichroism (CD), fluorescence spectroscopy, modulated differential scanning calorimetry and an in vitro bioactivity assay. Physical characterisation also included electron microscopy, tap density measurement and laser light diffraction. The aerosol aerodynamic performance of the formulations was assessed using the Andersen cascade impactor. Based on these studies, a formulation for spray freeze-drying was selected and the effects of the two particle engineering techniques on the biophysical stability and aerosol performance of the resulting powders was determined. CD, fluorescence spectroscopy and bioactivity data suggest that trehalose when used alone as a stabilising excipient produces a superior stabilising effect than when used in combination with a non-ionic surfactant. This highlights the utility of CD and fluorescence spectroscopy studies for the prediction of protein bioactivity post-processing. Therefore, a method and formulation suitable for the preparation of PTH as a dry powder was developed based on spray-drying PTH with trehalose as a stabiliser with the bioactivity of SD PTH containing trehalose being equivalent to that of unprocessed PTH. © 2011 American Association of Pharmaceutical Scientists

Nano-liposomal dry powder inhaler of tacrolimus: Preparation, characterization, and pulmonary pharmacokinetics

PubMed Central

Chougule, Mahavir; Padhi, Bijay; Misra, Ambikanandan

2007-01-01

The studies were undertaken to evaluate feasibility of pulmonary delivery of liposomaly encapsulated tacrolimus dry powder inhaler for prolonged drug retention in lungs as rescue therapy to prevent refractory rejection of lungs after transplantation. Tacrolimus encapsulated liposomes were prepared by thin film evaporation technique and liposomal dispersion was passed through high pressure homogenizer. Tacrolimus nano-liposomes (NLs) were separated by centrifugation and characterized. NLs were dispersed in phosphate buffer saline (PBS) pH 7.4 containing different additives like lactose, sucrose, and trehalose, and L-leucine as antiadherent. The dispersion was spray dried and spray dried powders were characterized. In vitro and in vivo pulmonary deposition was performed using Andersen Cascade Impactor and intratracheal instillation in rats respectively. NLs were found to have average size of 140 nm, 96% ± 1.5% drug entrapment, and zeta potential of 1.107 mV. Trehalose based formulation was found to have low density, good flowability, particle size of 9.46 ± 0.8 μm, maximum fine particle fraction (FPF) of 71.1 ± 2.5%, mean mass aerodynamic diameter (MMAD) 2.2 ± 0.1 μm, and geometric standard deviation (GSD) 1.7 ± 0.2. Developed formulations were found to have in vitro prolonged drug release up to 18 hours, following Higuchi’s Controlled Release model. In vivo studies revealed maximal residence of tacrolimus within lungs of 24 hours, suggesting slow clearance from the lungs. The investigation provides a practical approach for direct delivery of tacrolimus encapsulated in NLs for controlled and prolonged retention at the site of action. It may play a promising role as rescue therapy in reducing the risk of acute rejection and chronic rejection. PMID:18203434

The allergen Bet v 1 in fractions of ambient air deviates from birch pollen counts.

PubMed

Buters, J T M; Weichenmeier, I; Ochs, S; Pusch, G; Kreyling, W; Boere, A J F; Schober, W; Behrendt, H

2010-07-01

Proof is lacking that pollen count is representative for allergen exposure, also because allergens were found in nonpollen-bearing fractions of ambient air. We monitored simultaneously birch pollen and the major birch pollen allergen Bet v 1 in different size fractions of ambient air from 2004 till 2007 in Munich, Germany. Air was sampled with a ChemVol high-volume cascade impactor equipped with stages for particulate matter (PM)>10 microm, 10 microm>PM>2.5 microm, and 2.5 microm>PM>0.12 microm. Allergen was determined with a Bet v 1-specific ELISA. Pollen count was assessed with a Burkard pollen trap. We also measured the development of allergen in pollen during ripening. About 93 +/- 3% of Bet v 1 was found in the PM > 10 microm fraction, the fraction containing birch pollen. We did not measure any Bet v 1 in 2.5 microm > PM > 0.12 microm. Either in Munich no allergen was in this fraction or the allergen was absorbed to diesel soot particles that also deposit in this fraction. Pollen released 115% more Bet v 1 in 2007 than in 2004. Also within 1 year, the release of allergen from the same amount of pollen varied more than 10-fold between different days. This difference was explained by a rapidly increasing expression of Bet v 1 in pollen in the week just before pollination. Depending on the day the pollen is released during ripening, its potency varies. In general, pollen count and allergen in ambient air follow the same temporal trends. However, because a 10-fold difference can exist in allergen potency of birch pollen, symptoms might be difficult to correlate with pollen counts, but perhaps better with allergen exposure.

Evaluation of coarse and fine particles in diverse Indian environments.

PubMed

George, K V; Patil, Dinakar D; Anil, Mulukutla N V; Kamal, Neel; Alappat, Babu J; Kumar, Prashant

2017-02-01

The estimates of airborne fine particle (PM 2.5 ) concentrations are possible through rigorous empirical correlations based on the monitored PM 10 data. However, such correlations change depending on the nature of sources in diverse ambient environments and, therefore, have to be environment specific. Studies presenting such correlations are limited but needed, especially for those areas, where PM 2.5 is not routinely monitored. Moreover, there are a number of studies focusing on urban environments but very limited for coal mines and coastal areas. The aim of this study is to comprehensively analyze the concentrations of both PM 10 and PM 2.5 and develop empirical correlations between them. Data from 26 different sites spread over three distinct environments, which are a relatively clean coastal area, two coal mining areas, and a highly urbanized area in Delhi were used for the study. Distributions of PM in the 0.43-10-μm size range were measured using eight-stage cascade impactors. Regression analysis was used to estimate the percentage of PM 2.5 in PM 10 across distinct environments for source identification. Relatively low percentage of PM 2.5 concentrations (21, 28, and 32%) in PM 10 were found in clean coastal and two mining areas, respectively. Percentage of PM 2.5 concentrations in PM 10 in the highly urbanized area of Delhi was 51%, indicating a presence of a much higher percentage of fine particles due to vehicular combustion in Delhi. The findings of this work are important in estimating concentrations of much harmful fine particles from coarse particles across distinct environments. The results are also useful in source identification of particulates as differences in the percentage of PM 2.5 concentrations in PM 10 can be attributed to characteristics of sources in the diverse ambient environments.

Field comparison of three inhalable samplers (IOM, PGP-GSP 3.5 and Button) for welding fumes.

PubMed

Zugasti, Agurtzane; Montes, Natividad; Rojo, José M; Quintana, M José

2012-02-01

Inhalable sampler efficiency depends on the aerodynamic size of the airborne particles to be sampled and the wind speed. The aim of this study was to compare the behaviour of three personal inhalable samplers for welding fumes generated by Manual Metal Arc (MMA) and Metal Active Gas (MAG) processes. The selected samplers were the ones available in Spain when the study began: IOM, PGP-GSP 3.5 (GSP) and Button. Sampling was carried out in a welding training center that provided a homogeneous workplace environment. The static sampling assembly used allowed the placement of 12 samplers and 2 cascade impactors simultaneously. 183 samples were collected throughout 2009 and 2010. The range of welding fumes' mass concentrations was from 2 mg m(-3) to 5 mg m(-3). The pooled variation coefficients for the three inhalable samplers were less than or equal to 3.0%. Welding particle size distribution was characterized by a bimodal log-normal distribution, with MMADs of 0.7 μm and 8.2 μm. For these welding aerosols, the Button and the GSP samplers showed a similar performance (P = 0.598). The mean mass concentration ratio was 1.00 ± 0.01. The IOM sampler showed a different performance (P < 0.001). The mean mass concentration ratios were 0.90 ± 0.01 for Button/IOM and 0.92 ± 0.02 for GSP/IOM. This information is useful to consider the measurements accomplished by the IOM, GSP or Button samplers together, in order to assess the exposure at workplaces over time or to study exposure levels in a specific industrial activity, as welding operations.

Exposure assessment and heart rate variability monitoring in workers handling titanium dioxide particles: a pilot study

NASA Astrophysics Data System (ADS)

Ichihara, Sahoko; Li, Weihua; Omura, Seiichi; Fujitani, Yuji; Liu, Ying; Wang, Qiangyi; Hiraku, Yusuke; Hisanaga, Naomi; Wakai, Kenji; Ding, Xuncheng; Kobayashi, Takahiro; Ichihara, Gaku

2016-03-01

Titanium dioxide (TiO2) particles are used for surface coating and in a variety of products such as inks, fibers, food, and cosmetics. The present study investigated possible respiratory and cardiovascular effects of TiO2 particles in workers exposed to this particle at high concentration in a factory in China. The diameter of particles collected on filters was measured by scanning electron microscopy. Real-time size-dependent particle number concentration was monitored in the nostrils of four workers using condensation particle counter and optical particle counter. Electrocardiogram was recorded using Holter monitors for the same four workers to record heart rate variability. Sixteen workers underwent assessment of the respiratory and cardiovascular systems. Mass-based individual exposure levels were also measured with personal cascade impactors. The primary particle diameter ranged from 46 to 562 nm. Analysis of covariance of the pooled data of the four workers showed that number of particles with a diameter <300 nm was associated positively with total number of N-N and negatively with total number of increase or decrease in successive RR intervals greater than 50 ms (RR50+/-) or percentage of RR 50+/- that were parameters of parasympathetic function. The total mass concentration was 9.58-30.8 mg/m3 during work, but significantly less before work (0.36 mg/m3). The clear abnormality in respiratory function was not observed in sixteen workers who had worked for 10 months to 13 years in the factory. The study showed that exposure to particles with a diameter <300 nm might affect HRV in workers handling TiO2 particles. The results highlight the need to investigate the possible impact of exposure to nano-scaled particles on the autonomic nervous system.

Occurrence and particle-size distributions of polycyclic aromatic hydrocarbons in the ambient air of coking plant.

PubMed

Liu, Xiaofeng; Peng, Lin; Bai, Huiling; Mu, Ling; Song, Chongfang

2014-06-01

The purpose of this study was to characterize the occurrence and size distributions of ten species of polycyclic aromatic hydrocarbons (PAHs) in the ambient air of coking plants. Particulate-matter samples of four size fractions, including ≤2.1, 2.1-4.2, 4.2-10.2, and ≥10.2 μm, were collected using a Staplex234 cascade impactor during August 2009 at two coking plants in Shanxi, China. The PAHs were analyzed by a gas chromatograph equipped with a mass-selective detector. The concentrations of total particulate-matter PAHs were 1,412.7 and 2,241.1 ng/m(3) for plants I and II, and the distributions showed a peak within the 0.1-2.1 μm size range for plant I and the 0.1-4.2 μm for plant II. The size distributions of individual PAHs (except fluoranthene) exhibited a considerable peak within the 0.1-2.1 μm size range in coking plant I, which can be explained by the gas-particle partition mechanism. The ambient air of the coking plant was heavily polluted by PAHs associated with fine particles (≤2.1 μm), and benzo[b]fluoranthene made the largest contribution to total PAHs. The exposure levels of coking-plant workers to PAHs associated with fine particles were higher than to PAHs associated with coarse particles. Benzo[b]fluoranthene, benzo[a]pyrene, and dibenzo[a,h]anthracene should be the primary pollutants monitored in the coking plant. This research constitutes a significant contribution to assessing the exposure risk of coking-plant workers and providing basic data for PAH standards for ambient air in coking plants.

Conversion of polycyclic aromatic hydrocarbons on diesel particulate matter upon exposure to ppm levels of ozone

NASA Astrophysics Data System (ADS)

Van Vaeck, L.; Van Cauwenberghe, K.

Diesel exhaust particlulate matter samples were collected from a dilution tunnel using a Hi-Vol cascade impactor. The fraction of the aerosol with aerodynamic diameter below 0.5 μm, retained on the glass fiber back-up filter, was exposed to a flow of ozonised particle free air for periods of 0.5-4 h (1.5 ppm of O 3, flow rate about 40 m 3 h -1). Both exposed and non-exposed reference niters were Soxhlet-extracted with benzene and methanol, and the polycyclic aromatic hydrocarbon fraction (PAH) was isolated by a liquid-liquid partition procedure described in the literature, using cyclohexane and dimethylformamid-water as solvents, modified for quantitative recovery of PAH. The conversion yields of PAH upon exposure to O 3 were determined by single ion monitoring mass spectrometry using a fused silica capillary column for their separation. Significant conversion was observed for PAH from molecular weight 226 to 276. Approximate half lives are of the order of 0.5-1 h for most PAH measured. This high reactivity of PAH on a carbonaceous matrix is probably related to the large specific surface of soot particles as well as to their high adsorptive capacity for gaseous compounds. Lower molecular weight PAH up to chrysene also undergo important physical losses by volatilisation and the extent to which chemical transformations occurred could not be determined accurately. Different reactivities are observed for several isomeric pairs of PAH: benzo(a)pyrene is much faster converted than benzo(e)pyrene, benz(a)anthracene reacts faster than chrysene. The benzo-fluoranthenes are most resistant toward O 3 attack. The implications of these results with respect to atmospheric degradation of PAH, as well as to the occurrence of artefactual conversion upon Hi-Vol sampling are discussed.

XRF-analysis of fine and ultrafine particles emitted from laser printing devices.

PubMed

Barthel, Mathias; Pedan, Vasilisa; Hahn, Oliver; Rothhardt, Monika; Bresch, Harald; Jann, Oliver; Seeger, Stefan

2011-09-15

In this work, the elemental composition of fine and ultrafine particles emitted by ten different laser printing devices (LPD) is examined. The particle number concentration time series was measured as well as the particle size distributions. In parallel, emitted particles were size-selectively sampled with a cascade impactor and subsequently analyzed by the means of XRF. In order to identify potential sources for the aerosol's elemental composition, materials involved in the printing process such as toner, paper, and structural components of the printer were also analyzed. While the majority of particle emissions from laser printers are known to consist of recondensated semi volatile organic compounds, elemental analysis identifies Si, S, Cl, Ca, Ti, Cr, and Fe as well as traces of Ni and Zn in different size fractions of the aerosols. These elements can mainly be assigned to contributions from toner and paper. The detection of elements that are likely to be present in inorganic compounds is in good agreement with the measurement of nonvolatile particles. Quantitative measurements of solid particles at 400 °C resulted in residues of 1.6 × 10(9) and 1.5 × 10(10) particles per print job, representing fractions of 0.2% and 1.9% of the total number of emitted particles at room temperature. In combination with the XRF results it is concluded that solid inorganic particles contribute to LPD emissions in measurable quantities. Furthermore, for the first time Br was detected in significant concentrations in the aerosol emitted from two LPD. The analysis of several possible sources identified the plastic housings of the fuser units as main sources due to substantial Br concentrations related to brominated flame retardants.

Emission Factors, Size Distributions and Emission Inventories of Carbonaceous Particulate Matter from Residential Wood Combustion in Rural China

PubMed Central

Shen, Guofeng; Wei, Siye; Wei, Wen; Zhang, Yanyan; Min, Yujia; Wang, Bin; Wang, Rong; Li, Wei; Shen, Huizhong; Huang, Ye; Huang, Ye; Yang, Yifeng; Wang, Wei; Wang, Xilong; Wang, Xuejun; Tao, Shu

2012-01-01

Published emission factors (EFs) often vary significantly, leading to high uncertainties in emission estimations. There are few reliable EFs from field measurements of residential wood combustion in China. In this study, 17 wood fuels and one bamboo were combusted in a typical residential stove in rural China to measure realistic EFs of particulate matter (PM), organic carbon (OC) and elemental carbon (EC), as well as to investigate the influence of fuel properties and combustion conditions on the EFs. Measured EFs of PM, OC, and EC (EFPM, EFOC, and EFEC, respectively) were in the range of 0.38~6.4, 0.024~3.0 and 0.039~3.9 g/kg (dry basis), with means and standard derivation of 2.2±1.2, 0.62±0.64 and 0.83±0.69 g/kg, respectively. Shrubby biomass combustion produced higher EFs than tree woods, and both species had lower EFs than those of indoor crop residue burning (p<0.05). Significant correlations between EFPM, EFOC and EFEC were expected. By using a nine-stage cascade impactor, it was shown that size distributions of PM emitted from tree biomass combustions were unimodal with peaks at a diameter less than 0.4 µm (PM0.4), much finer than the PM from indoor crop residue burning. Approximately 79.4% of the total PM from tree wood combustion was PM with a diameter less than 2.1µm (PM2.1). PM size distributions for shrubby biomasses were slightly different from those for tree fuels. Based on the measured EFs, total emissions of PM, OC, and EC from residential wood combustion in rural China in 2007 were estimated at about 303, 75.7, and 92.0 Gg. PMID:22380753

Size-segregated urban aerosol characterization by electron microscopy and dynamic light scattering and influence of sample preparation

NASA Astrophysics Data System (ADS)

Marvanová, Soňa; Kulich, Pavel; Skoupý, Radim; Hubatka, František; Ciganek, Miroslav; Bendl, Jan; Hovorka, Jan; Machala, Miroslav

2018-04-01

Size-segregated particulate matter (PM) is frequently used in chemical and toxicological studies. Nevertheless, toxicological in vitro studies working with the whole particles often lack a proper evaluation of PM real size distribution and characterization of agglomeration under the experimental conditions. In this study, changes in particle size distributions during the PM sample manipulation and also semiquantitative elemental composition of single particles were evaluated. Coarse (1-10 μm), upper accumulation (0.5-1 μm), lower accumulation (0.17-0.5 μm), and ultrafine (<0.17 μm) PM fractions were collected by high volume cascade impactor in Prague city center. Particles were examined using electron microscopy and their elemental composition was determined by energy dispersive X-ray spectroscopy. Larger or smaller particles, not corresponding to the impaction cut points, were found in all fractions, as they occur in agglomerates and are impacted according to their aerodynamic diameter. Elemental composition of particles in size-segregated fractions varied significantly. Ns-soot occurred in all size fractions. Metallic nanospheres were found in accumulation fractions, but not in ultrafine fraction where ns-soot, carbonaceous particles, and inorganic salts were identified. Dynamic light scattering was used to measure particle size distribution in water and in cell culture media. PM suspension of lower accumulation fraction in water agglomerated after freezing/thawing the sample, and the agglomerates were disrupted by subsequent sonication. Ultrafine fraction did not agglomerate after freezing/thawing the sample. Both lower accumulation and ultrafine fractions were stable in cell culture media with fetal bovine serum, while high agglomeration occurred in media without fetal bovine serum as measured during 24 h.

Structural Analysis of the QCM Aboard the ER-2

NASA Technical Reports Server (NTRS)

Jones, Phyllis D.; Bainum, Peter M.; Xing, Guangqian

1997-01-01

As a result of recent supersonic transport (SST) studies on the effect they may have on the atmosphere, several experiments have been proposed to capture and evaluate samples of the stratosphere where SST's travel. One means to achieve this is to utilize the quartz crystal microbalance (QCM) installed aboard the ER-2, formerly the U-2 reconnaissance aircraft. The QCM is a cascade impactor designed to perform in-situ, real-time measurements of aerosols and chemical vapors at an altitude of 60,000 - 70,000 feet. The ER-2 is primarily used by NASA for Earth resources to test new sensor systems before they are placed aboard satellites. One of the main reasons the ER-2 is used for this flight experiment is its capability to fly approximately twelve miles above sea level (can reach an altitude of 78,000 feet). Because the ER-2 operates at such a high altitude, it is of special interest to scientists interested in space exploration or supersonic aircraft. Some of the experiments are designed to extract data from the atmosphere around the ER-2. For the current flight experiment, the QCM is housed in a frame that is connected to an outer pod that is attached to the fuselage of the ER-2. Due to the location of the QCM within the housing frame and the location of the pod on the ER-2, the pod and its contents are subject to structural loads. In addition to structural loads, structural vibrations are also of importance because the QCM is a frequency induced instrument. Therefore, a structural analysis of the instrument within the frame is imperative to determine if resonance and/or undesirable deformations occur.

[Polycyclic aromatic hydrocarbons in ultrafine particles of diesel exhaust fumes--the use of ultrafast liquid chromatography].

PubMed

Małgorzata Szewczyńska; Małgorzata Pośniak

2014-01-01

The article presents the results of the determination of polycyclic aromatic hydrocarbons (PAHs) in the fine par ticles fraction emitted from 3 types of diesel fuels using ultra-high pressure liquid chromatography. Samples of diesel Eco, Verwa and Bio exhaust combustion fumes were generated at the model station which consisted of a diesel engine from the 2007 Diesel TDI 2.0. Personal Cascade Sioutas Impactor (IPCSI) with Teflon filters was used to collect samples of exhaust fume ultrafine particles. PAHs adsorbed on particulate fractions were analyzed by ultra-high pressure liquid chromatography with fluorescence detection (UHPLC/FL). Phenanthrene, fluoranthene, pyrene and chrysene present the highest concentration in the particulate matter emitted by an engine. The total contents of fine particles collected during engine operation on fuels Eco, Verwa and Bio were 134.2 μg/g, 183.8 μg/g and 153.4 μg/g, respectively, which makes 75%, 90% and 83% of the total PAHs, respectively. The highest content of benzo(a)pyrene determined in particles emitted during the combustion of fuels Eco and Bio was 1.5 μg/g and 1 μg/g, respectively. The study of the PAH concentration in the particles of fine fraction below 0.25 μm emitted from different fuels designed for diesel engines indicate that the exhaust gas content of carcinogens, including PAHs deposited on particulates, is still significant, regardless of the fuel. Application of ultrahigh pressure liquid chromatography with fluorescence detection for the analysis ofPAHs in the particles emitted in the fine fraction of diesel exhaust allowed to shorten the analysis time from 35 min to 8 min.

Seasonal variation of the particle size distribution of n-alkanes and polycyclic aromatic hydrocarbons (PAHs) in urban aerosol of Guangzhou, China.

PubMed

Tang, X L; Bi, X H; Sheng, G Y; Tan, J H; Fu, J M

2006-06-01

Seasonal aerosol samples have been collected by Andersen Hi-Vol pumping system equipped with a five stage cascade impactor and a backup filter (size range: 10-7.2 microm, 7.2-3.0 microm, 3.0-1.5 microm, 1.5-0.95 microm, 0.95-0.49 microm,

Roughness-controlled self-assembly of mannitol/LB agar microparticles by polymorphic transformation for pulmonary drug delivery.

PubMed

Zhang, Fengying; Ngoc, Nguyen Thi Quynh; Tay, Bao Hui; Mendyk, Aleksander; Shao, Yu-Hsuan; Lau, Raymond

2015-01-05

Novel roughness-controlled mannitol/LB Agar microparticles were synthesized by polymorphic transformation and self-assembly method using hexane as the polymorphic transformation reagent and spray-dried mannitol/LB Agar microparticles as the starting material. As-prepared microparticles were characterized by Fourier transform infrared spectra (FTIR), X-ray diffraction spectra (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and Andersen Cascade Impactor (ACI). The XRD and DSC results indicate that after immersing spray-dried mannitol/LB Agar microparticles in hexane, β-mannitol was completely transformed to α-mannitol in 1 h, and all the δ-mannitol was transformed to α form after 14 days. SEM shows that during the transformation the nanobelts on the spray-dried mannitol/LB Agar microparticles become more dispersed and the contour of the individual nanobelts becomes more noticeable. Afterward, the nanobelts self-assemble to nanorods and result in rod-covered mannitol/LB Agar microparticles. FTIR indicates new hydrogen bonds were formed among mannitol, LB Agar, and hexane. SEM images coupled with image analysis software reveal that different surface morphology of the microparticles have different drug adhesion mechanisms. Comparison of ACI results and image analysis of SEM images shows that an increase in the particle surface roughness can increase the fine particle fractions (FPFs) using the rod-covered mannitol microparticles as drug carriers. Transformed microparticles show higher FPFs than commercially available lactose carriers. An FPF of 28.6 ± 2.4% was achieved by microparticles transformed from spray-dried microparticles using 2% mannitol(w/v)/LB Agar as feed solution. It is comparable to the highest FPF reported in the literature using lactose and spray-dried mannitol as carriers.

Integrated chemical/biochemical sample collection, pre-concentration, and analysis on a digital microfluidic lab-on-a-chip platform

NASA Astrophysics Data System (ADS)

Fair, Richard B.; Khlystov, A.; Srinivasan, Vijay; Pamula, Vamsee K.; Weaver, Kathryn N.

2004-12-01

An ideal on-site chemical/biochemical analysis system must be inexpensive, sensitive, fully automated and integrated, reliable, and compatible with a broad range of samples. The advent of digital microfluidic lab-on-a-chip (LoC) technology offers such a detection system due to the advantages in portability, reduction of the volumes of the sample and reagents, faster analysis times, increased automation, low power consumption, compatibility with mass manufacturing, and high throughput. We describe progress towards integrating sample collection onto a digital microfluidic LoC that is a component of a cascade impactor device. The sample collection is performed by impacting airborne particles directly onto the surface of the chip. After the collection phase, the surface of the chip is washed with a micro-droplet of solvent. The droplet will be digitally directed across the impaction surface, dissolving sample constituents. Because of the very small droplet volume used for extraction of the sample from a wide colection area, the resulting solution is realatively concentrated and the analytes can be detected after a very short sampling time (1 min) due to such pre-concentration. After the washing phase, the droplet is mixed with specific reagents that produce colored reaction products. The concentration of the analyte is quantitatively determined by measuring absorption at target wavelengths using a simple light emitting diode and photodiode setup. Specific applications include automatic measurements of major inorganic ions in aerosols, such as sulfate, nitrate and ammonium, with a time resolution of 1 min and a detection limit of 30 nm/m3. We have already demonstrated the detection and quantification of nitroaromatic explosives without integrating the sample collection. Other applications being developed include airborne bioagent detection.

[Size distribution of particle and polycyclic aromatic hydrocarbons in particle emissions from simulated emission sources].

PubMed

Fu, Hai-Huan; Tian, Na; Shang, Hui-Bin; Zhang, Bin; Ye, Su-Fen; Chen, Xiao-Qiu; Wu, Shui-Ping

2014-01-01

Particles from cooking lampblack, biomass and plastics burning smoke, gasoline vehicular exhausts and gasoline generator exhausts were prepared in a resuspension test chamber and collected using a cascade MOUDI impactor. A total of 18 polycyclic aromatic hydrocarbons (PAHs) associated with particles were analyzed by GC-MS. The results showed that there were two peaks in the range of 0.44-1.0 microm and 2.5-10 microm for cooking lampblack, and only one peak in the range of 0.44-1.0 microm for straw and wood burning smoke. But there were no clear peak for plastics burning smoke. The peak for gasoline vehicular exhausts was found in the range of 2.5-10 microm due to the influence of water vapor associated with particles, while the particles from gasoline generator exhausts were mainly in the range of < or = 2.5 microm (accounting for 93% of the total mass). The peak in 2.5-10 microm was clear for cooking lampblack and gasoline vehicular exhausts. The peak in the range of 0.44-1.0 microm became more and more apparent with the increase of PAHs molecular weight. The fraction of PAH on particles less than 1.0 microm to that on the total particles increased along with PAH's molecular weight. Phenanthrene was the dominant compound for cooking lampblack and combustion smoke, while gasoline vehicular exhausts and generator exhausts were characterized with significantly high levels of naphthalene and benzo[g, h, i] perylene, respectively. The distribution of source characteristic ratios indicated that PAHs from cooking lampblack and biomass burning were close and they were different from those of vehicular exhausts and generator exhausts.

Endotoxin in Size-Separated Metal Working Fluid Aerosol Particles.

PubMed

Dahlman-Höglund, Anna; Lindgren, Åsa; Mattsby-Baltzer, Inger

2016-08-01

Patients with airway symptoms working in metal working industries are increasing, despite efforts to improve the environmental air surrounding the machines. Our aim was to analyse the amount of endotoxin in size-separated airborne particles of metal working fluid (MWF) aerosol, by using the personal sampler Sioutas cascade impactor, to compare filter types, and to compare the concentration of airborne endotoxin to that of the corresponding MWFs. In a pilot field study, aerosols were collected in two separate machine halls on totally 10 occasions, using glass fibre and polytetrafluoroethylene (PTFE) filters in parallel at each station. Airborne endotoxin was distributed over all size fractions. While a major part was found in the largest size fraction (72%, 2.5-10 µm), up to 8% of the airborne endotoxin was detected in the smallest size fraction (<0.25 µm). Comparing the efficiency of the filter types, a significantly higher median endotoxin level was found with glass fibres filters collecting the largest particle-size fraction (1.2-fold) and with PTFE filters collecting the smallest ones (5-fold). The levels of endotoxin in the size-separated airborne particle fractions correlated to those of the MWFs supporting the aerosol-generating machines. Our study indicates that a significant part of inhalable aerosols of MWFs consists of endotoxin-containing particles below the size of intact bacteria, and thus small enough to readily reach the deepest part of the lung. Combined with other chemical irritants of the MWF, exposure to MWF aerosols containing endotoxin pose a risk to respiratory health problems. © The Author 2016. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Morphology and Chemical Composition of soot particles emitted by Wood-burning Cook-Stoves: a HRTEM, XPS and Elastic backscattering Studies.

NASA Astrophysics Data System (ADS)

Carabali-Sandoval, G. A., Sr.; Castro, T.; Peralta, O.; De la Cruz, W.; Días, J.; Amelines, O.; Rivera-Hernández, M.; Varela, A.; Muñoz-Muñoz, F.; Policroniades, R.; Murillo, G.; Moreno, E.

2014-12-01

The morphology, microstructure and the chemical composition on surface of soot particles were studied by using high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and elastic backscattering spectrometry. In order to obtain freshly soot particles emitted by home-made wood-burning cook stoves, copper grids for Transmission Electron Microscope (TEM) were placed on the last two of an 8-stages MOUDI cascade impactor. The analysis of HRTEM micrographs revealed the nanostructure and the particle size of soot particles. The XPS survey spectra show a large carbon peak around 285 eV and the oxygen signal at 533 eV. Some differences observed in the carbon/oxygen (C/O) ratio of the particles probably depend on the combustion process efficiency of each cook-stove analyzed. The C-1s XPS spectra show an asymmetric broad peak and other with low intensity that corresponds to sp2 and sp3hybridization, which were fitted with a convolution using Gaussian functions. Elastic backscattering technique allows a chemical elemental analysis of samples and confirms the presence of C, O and Si observed by XPS. Additionally, the morphological properties of soot aggregates were analyzed calculating the border-based fractal dimension (Df). Particles exhibit complex shapes with high values of Df. Also, real-time absorption (σabs) and scattering (σsct) coefficients of fine (with aerodynamic diameter < 2.5 µm) soot particles were measured. The trend in σabs and σsct indicate that the cooking process has two important combustion stages which varied in its flaming strength, being vigorous in the first stage and soft in the second one.

Polycyclic aromatic hydrocarbons associated with particles in ambient air from urban and industrial areas.

PubMed

Rehwagen, Martina; Müller, Andrea; Massolo, Laura; Herbarth, Olf; Ronco, Alicia

2005-09-15

This study takes into consideration an analysis of the chemical polycyclic aromatic hydrocarbon (PAH) profile and its distribution in inhalable and respirable particulate matter in urban and industrial areas in La Plata, Argentina, and Leipzig, Germany. Representative samples from three locations in La Plata (industrial, traffic influenced and control area) and two locations in Leipzig (traffic influenced and control area) were obtained in summer and winter. The sampling of particulate matter was carried out with high volume collectors using cascade impactors to separate six size fractions. PAHs were extracted with hexane through a solid-liquid equilibrium extraction and analysed by HPLC/UV/fluorescence detection. The results showed a PAH seasonal behaviour in both regions, with lower contents in summer and higher ones in winter. Highest concentrations of total PAHs were found in the industrial area in La Plata. The size distribution of particles demonstrates the greater relevance of smaller particles. More than 50% of PAHs were associated with particles of less than 0.49 microm. Moreover, this particle size fraction was associated with traffic, whereas other sources of combustion were related also to particles between 0.49 and 0.95 microm. Considering the ratio of benzo(ghi)perylene (BgP)/benzo(a)pyrene (BaP) as an indicator for traffic influence, it was observed that La Plata City was more affected than Leipzig by the same proportion in summer and in winter. The BgP/InP (indeno(123-cd)pyrene) ratio was lower in winter than in summer in both places and indicates the presence of domestic combustion sources. It is important to point out the significance of using fingerprint compound ratios to identify possible sources of pollution with PAHs bound to particles.

PM 10, PM 2.5 and PM 1.0—Emissions from industrial plants—Results from measurement programmes in Germany

NASA Astrophysics Data System (ADS)

Ehrlich, C.; Noll, G.; Kalkoff, W.-D.; Baumbach, G.; Dreiseidler, A.

Emission measurement programmes were carried out at industrial plants in several regions of Germany to determine the fine dust in the waste gases; the PM 10, PM 2.5 and PM 1.0 fractions were sampled using a cascade impactor technique. The installations tested included plants used for: combustion (brown coal, heavy fuel oil, wood), cement production, glass production, asphalt mixing, and processing plants for natural stones and sand, ceramics, metallurgy, chemical production, spray painting, wood processing/chip drying, poultry farming and waste treatment. In addition waste gas samples were taken from small-scale combustion units, like domestic stoves, firing lignite briquettes or wood. In total 303 individual measurement results were obtained during 106 different measurement campaigns. In the study it was found that in more than 70% of the individual emission measurement results from industrial plants and domestic stoves the PM 10 portion amounted to more than 90% and the PM 2.5 portion between 50% and 90% of the total PM (particulate matter) emission. For thermal industrial processes the PM 1.0 portion constituted between 20% and 60% of the total PM emission. Typical particle size distributions for different processes were presented as cumulative frequency distributions and as frequency distributions. The particle size distributions determined for the different plant types show interesting similarities and differences depending on whether the processes are thermal, mechanical, chemical or mixed. Consequently, for the groups of plant investigated, a major finding of this study has been that the particle size distribution is a characteristic of the industrial process. Attempts to correlate particle size distributions of different plants to different gas cleaning technologies did not lead to usable results.

Control of particle size by coagulation of novel condensation aerosols in reservoir chambers.

PubMed

Hong, John N; Hindle, Michael; Byron, Peter R

2002-01-01

The coagulation growth behavior of capillary aerosol generator (CAG) condensation aerosols was investigated in a series of reservoir chambers. Aerosols consisted of a condensed system of 0.7% w/w benzil (model drug) in propylene glycol (vehicle). These were generated into 250-, 500-, 1,000-, and 2,000-mL reservoirs in both flowing air-stream and static air experiments. Changes in drug and total aerosol particle size were measured by a MOUDI cascade impactor. In both series of experiments the CAG aerosols grew in size. Growth in flowing air-stream experiments was attributed to the amount of accumulation aerosols experienced in reservoirs during sampling and increased with increasing reservoir volume. Mean (SD) MMAD's for the total mass distribution measured for the 250- and 2,000-mL reservoirs were 0.70 (0.02) and 0.87 (0.03) microm, respectively. For the benzil mass distribution, they were 0.64 (0.02) and 0.87 (0.06) microm, respectively. Growth in static air experiments was dependent on the volume aerosol boluses were restricted to and increased with decreasing reservoir volume. Mean (SD) initial MMAD's for the benzil mass distribution for the 250- and 2,000-mL reservoirs were 1.44 (0.03) and 1.24 (0.08) microm, respectively. Holding aerosols for up to 60 sec further increased their size. Mean (SD) MMAD's for benzil after holding for 60 sec in these reservoirs were 2.28 (0.04) and 1.67 (0.09) microm, respectively. The coagulation behavior and therefore particle size of CAG aerosols may be modified and controlled by reservoir chambers for drug targeting within the respiratory tract.

Solvent extracted organic matter and polycyclic aromatic hydrocarbons distributed in size-segregated airborne particles in a zone of México City: Seasonal behavior and human exposure

NASA Astrophysics Data System (ADS)

Amador-Muñoz, Omar; Villalobos-Pietrini, Rafael; Agapito-Nadales, Ma. Cristina; Munive-Colín, Zenaida; Hernández-Mena, Leonel; Sánchez-Sandoval, Magdalena; Gómez-Arroyo, Sandra; Bravo-Cabrera, José Luis; Guzmán-Rincón, Judith

2010-01-01

Airborne particulate mass was collected in a cascade impactor, and the mass concentration of solvent extracted organic matter (SEOM) and polycyclic aromatic hydrocarbons (PAH) were determined. A greater mass concentration of particles, SEOM and PAH were obtained in the dry season than in the rainy season for all impact stages; however, in the rainy season the proportion of SEOM/particles mass increased for all stages. There was an average decrease in particle mass concentration of 52.1 ± 6.7%, a 33.6 ± 12.3% decrease in SEOM and a 43.9 ± 16.9% decrease in heavy PAH (≥228 g mol -1) in the rainy season. Heavy PAH were distributed in fine particles, while light PAH were more abundant in coarse particles. Estimations of SEOM and PAH inhaled daily by a person were made. Considering the carcinogenic PAH median mass (10th-90th percentiles) in 20 m 3 of air, and the sum of all stages that could be inhaled daily by a person, estimates of 137 ng day -1 (74-246) in the dry season and 57 ng day -1 (21-101) in the rainy season were determined. The toxic equivalent factors were calculated to more accurately characterize the carcinogenic properties of PAH mixtures. This was based on the contribution of the carcinogenic potency of benzo[ a]pyrene. These estimations would need to be considered in establishing standards for Mexican air quality. Correlations were shown between other atmospheric pollutants and masses of particles, SEOM and PAH. Vehicles were suggested as an emission source for SEOM and PAH.

Evaluation of new in vitro efficacy test for antimicrobial surface activity reflecting UK hospital conditions.

PubMed

Ojeil, M; Jermann, C; Holah, J; Denyer, S P; Maillard, J-Y

2013-12-01

Antimicrobial surfaces aim to reduce microbial bioburden and improve hygiene. The current antimicrobial surface efficacy test (ISO22196) is an initial screening test but its conditions, high temperature (37°C) and relative humidity (RH) (100%) bear little relationship to in-use conditions. To develop an antimicrobial surface efficacy test providing a realistic second-tier test, simulating in-use conditions. Surface relative humidity, temperature and soiling were measured over one year at a UK hospital, enabling realistic parameters to be set for our surface efficacy test. A nebulizer, connected to a cascade impactor, aerosolized and uniformly deposited a Staphylococcus aureus suspension over test copper alloys and control stainless steel surfaces. Bacteria were enumerated following nebulization, and after a range of contact times, under [20°C, 50% RH] and [20°C, 40% RH] parameters reflecting in-use conditions; [37°C, 100% RH] was employed to reflect conditions used in ISO22196. All copper alloys produced a >4 log10 reduction after 24h under all conditions tested. Copper alloys were more effective at [37°C, 100% RH] showing a >4 log10 reduction after 30 min than at in-use conditions [20°C, 50% RH and 20°C, 40% RH], for which 60 min was required to achieve the same level of kill, for most but not all alloys. The use of the nebulizer to deposit bacterial inocula on surfaces showed little variability in results. Our method was more discriminatory than the ISO22196 enabling distinction between the bactericidal surface activity, which allows for a more rigorous selection of antimicrobial surfaces for potential use in healthcare settings. Copyright © 2013 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

Analysis of impact energy to fracture un-notched charpy specimens made from railroad tank car steel

DOT National Transportation Integrated Search

2007-09-11

This paper describes a nonlinear finite element analysis : (FEA) framework that examines the impact energy to fracture : unnotched Charpy specimens by an oversized, nonstandard : pendulum impactor called the Bulk Fracture Charpy Machine : (BFCM). The...

Detailed puncture analyses tank cars : analysis of different impactor threats and impact conditions.

DOT National Transportation Integrated Search

2013-03-01

There has been significant research in recent years to analyze and improve the impact behavior and puncture resistance of railroad tank cars. Much of this research has been performed using detailed nonlinear finite element analyses supported by full ...

The protective effects of dexmedetomidine on ischemic brain injury: A meta-analysis.

PubMed

Jiang, Lianxiang; Hu, Meizhu; Lu, Yan; Cao, Ya; Chang, Yan; Dai, Zeping

2017-08-01

Intracranial lesions, trauma or surgery-related damage activate immune inflammation and neuroendocrine responses, causing ischemic brain injury. Studies have shown that inflammatory cascade mediated by neuroendocrine hormones and proinflammatory mediators is implicated in the pathophysiology of ischemic brain injury. Alpha2-adrenoceptor agonists, dexmedetomidine, is widely used as neuroprotectants in anesthesia practice. However, it is still lack of a comprehensive meta-analysis to evaluate the neuroprotection of dexmedetomidine against ischemic brain injury via suppressing these two physiological responses. Searched the Cochrane Library, Pub-Med, EMBASE, EBSCO, Ovid, Chinese biological and medical database (CBM). Related literatures published in English or Chinese before January 2017 were enrolled. We assessed the quality of eligible studies and synthesized predefined outcomes with a random-effects model or fixed-effects model. Nineteen Randomized Controlled Trials including 879 patients were included. Findings for meta-analysis of various outcomes were summarised. Primary results shown that compared with placebo, dexmedetomidine reduced a surge of TNF-α [SMD=-2.34, 95%CI (-3.25, -1.44)], IL-6 [SMD=-2.44, 95%CI (-3.40, -1.47)], S100-β [SMD=-2.73, 95%CI (-3.65, -1.82)], NSE [SMD=-1.69, 95%CI (-2.77, -0.61)], cortisol [SMD=-2.48, 95%CI (-3.38, -1.58)] and glucose [SMD=-1.44, 95%CI (-1.85, -1.04)]; maintained the level of SOD [SMD=1.36, 95%CI (0.62, 2.10)]; decreased the rise in CRP level at postoperative one day. In response to stress reaction, dexmedetomidine attenuated the stress-related increasing of MAP, HR and intracranial pressure without significant effects on cerebral oxygen metabolism. Alpha2-adrenoceptor agonists, dexmedetomidine, could reduce the release of inflammatory mediators and neuroendocrine hormones as well as maintain intracranial homoeostasis, alleviating ischemic brain injury and exerting an effect on brain protection. Copyright © 2017 Elsevier Inc. All rights reserved.

Interleukin 6 Inhibition and Coronary Artery Disease in a High-Risk Population: A Prospective Community-Based Clinical Study.

PubMed

Bacchiega, Bruno Cesar; Bacchiega, Ana Beatriz; Usnayo, Magali Justina Gomez; Bedirian, Ricardo; Singh, Gurkirpal; Pinheiro, Geraldo da Rocha Castelar

2017-03-13

Atherosclerosis is a chronic inflammatory disease, with interleukin 6 (IL-6) as a major player in inflammation cascade. IL-6 blockade may reduce cardiovascular risk, but current treatments to block IL-6 also induce dyslipidemia, a finding with an uncertain prognosis. We aimed to determine the endothelial function responses to the IL-6-blocking agent tocilizumab, anti-tumor necrosis factor α, and synthetic disease-modifying antirheumatic drug therapies in patients with rheumatoid arthritis in a 16-week prospective study. Sixty consecutive patients with rheumatoid arthritis were enrolled. Tocilizumab and anti-tumor necrosis factor α therapy were started in 18 patients each while 24 patients were treated with synthetic disease-modifying antirheumatic drugs. Forty patients completed the 16-week follow-up period. The main outcome was flow-mediated dilation percentage variation before and after therapy. In the tocilizumab group, flow-mediated dilation percentage variation increased statistically significantly from a pre-treatment mean of (3.43% [95% CI, 1.28-5.58] to 5.96% [95% CI, 3.95-7.97]; P =0.03). Corresponding changes were 4.78% (95% CI, 2.13-7.42) to 6.75% (95% CI, 4.10-9.39) ( P =0.09) and 2.87% (95% CI, -2.17 to 7.91) to 4.84% (95% CI, 2.61-7.07) ( P =0.21) in the anti-tumor necrosis factor α and the synthetic disease-modifying antirheumatic drug groups, respectively (both not statistically significant). Total cholesterol increased significantly in the tocilizumab group from 197.5 (95% CI, 177.59-217.36) to 232.3 (201.62-263.09) ( P =0.003) and in the synthetic disease-modifying antirheumatic drug group from 185.8 (95% CI, 169.76-201.81) to 202.8 (95% CI, 176.81-228.76) ( P =0.04), but not in the anti-tumor necrosis factor α group. High-density lipoprotein did not change significantly in any group. Endothelial function is improved by tocilizumab in a high-risk population, even as it increases total cholesterol and low-density lipoprotein levels. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Secondary ion mass spectrometry (SIMS) analysis of hypervelocity microparticle impact sites on LDEF surfaces

NASA Technical Reports Server (NTRS)

Simon, C. G.; Buonaquisti, A. J.; Batchelor, D. A.; Hunter, J. L.; Griffis, D. P.; Misra, V.; Ricks, D. R.; Wortman, J. J.; Brownlee, D. E.; Best, S. R.

1995-01-01

Two dimensional elemental ion maps have been recorded for hundreds of microparticle impact sites and contamination features on LDEF surfaces. Since the majority of the analyzed surfaces were metal-oxide-silicon (MOS) impact detectors from the Interplanetary Dust Experiment, a series of 'standard' and 'blank' analyses of these surfaces are included. Hypervelocity impacts of forsterite olivine microparticles on activated flight sensors served as standards while stylus and pulsed laser simulated 'impacts' served as analytical blanks. Results showed that despite serious contamination issues, impactor residues can be identified in greater than 1/3 of the impact sites. While aluminum oxide particles could not be detected on aluminum surfaces, they were detected on germanium surfaces from row 12. Remnants of manmade debris impactors consisting of paint chips and bits of metal were identified on surfaces from LDEF Rows 3 (west or trailing side), 6 (south), 9 (ram or leading side), 12 (north) and the space end. Higher than expected ratios of manmade microparticle impacts to total microparticle impacts were found on the space end and the trailing side. These results were consistent with time-tagged and time-segregated microparticle impact data from the IDE and other LDEF experiments. A myriad of contamination interferences were identified and their effects on impactor debris identification mitigated during the course of this study. These interferences include pre-, post and inflight deposited surface contaminants as well as indigenous heterogeneous material contaminants. Non-flight contaminations traced to human origins, including spittle and skin oils, contributed significant levels of alkali-rich carbonaceous interferences. A ubiquitous layer of in-flight deposited silicaceous contamination varied in thickness with location on LDEF, even on a micro scale. In-flight deposited (low velocity) contaminants include urine droplets and bits of metal film from eroded thermal blankets.

The current impact flux on Mars and its seasonal variation

NASA Astrophysics Data System (ADS)

JeongAhn, Youngmin; Malhotra, Renu

2015-12-01

We calculate the present-day impact flux on Mars and its variation over the martian year, using the current data on the orbital distribution of known Mars-crossing minor planets. We adapt the Öpik-Wetherill formulation for calculating collision probabilities, paying careful attention to the non-uniform distribution of the perihelion longitude and the argument of perihelion owed to secular planetary perturbations. We find that, at the current epoch, the Mars crossers have an axial distribution of the argument of perihelion, and the mean direction of their eccentricity vectors is nearly aligned with Mars' eccentricity vector. These previously neglected angular non-uniformities have the effect of depressing the mean annual impact flux by a factor of about 2 compared to the estimate based on a uniform random distribution of the angular elements of Mars-crossers; the amplitude of the seasonal variation of the impact flux is likewise depressed by a factor of about 4-5. We estimate that the flux of large impactors (of absolute magnitude H < 16) within ±30° of Mars' aphelion is about three times larger than when the planet is near perihelion. Extrapolation of our results to a model population of meter-size Mars-crossers shows that if these small impactors have a uniform distribution of their angular elements, then their aphelion-to-perihelion impact flux ratio would be 11-15, but if they track the orbital distribution of the large impactors, including their non-uniform angular elements, then this ratio would be about 3. Comparison of our results with the current dataset of fresh impact craters on Mars (detected with Mars-orbiting spacecraft) appears to rule out the uniform distribution of angular elements.

Evaluation of a novel personal nanoparticle sampler.

PubMed

Zhou, Yue; Irshad, Hammad; Tsai, Chuen-Jinn; Hung, Shao-Ming; Cheng, Yung-Sung

2014-02-01

This work investigated the performance in terms of collection efficiency and aspiration efficiency of a personal sampler capable of collecting ultrafine particles (nanoparticles) in the occupational environment. This sampler consists of a cyclone for respirable particle classification, micro-orifice impactor stages with an acceleration nozzle to achieve nanoparticle classification and a backup filter to collect nanoparticles. Collection efficiencies of the cyclone and impactor stages were determined using monodisperse polystyrene latex and silver particles, respectively. Calibration of the cyclone and impactor stages showed 50% cut-off diameters of 3.95 μm and 94.7 nm meeting the design requirements. Aspiration efficiencies of the sampler were tested in a wind tunnel with wind speeds of 0.5, 1.0, and 1.5 m s(-1). The test samplers were mounted on a full size mannequin with three orientations toward the wind direction (0°, 90°, and 180°). Monodisperse oleic acid aerosols tagged with sodium fluorescein in the size range of 2 to 10 μm were used in the test. For particles smaller than 2 μm, the fluorescent polystyrene latex particles were generated by using nebulizers. For comparison of the aspiration efficiency, a NIOSH two-stage personal bioaerosol sampler was also tested. Results showed that the orientation-averaged aspiration efficiency for both samplers was close to the inhalable fraction curve. However, the direction of wind strongly affected the aspiration efficiency. The results also showed that the aspiration efficiency was not affected by the ratio of free-stream velocity to the velocity through the sampler orifice. Our evaluation showed that the current design of the personal sampler met the designed criteria for collecting nanoparticles ≤100 nm in occupational environments.

Coastal California's Fog Aerobiology and Ecology: Designing and Testing an Optimal Passive Impactor Collection Unit

NASA Astrophysics Data System (ADS)

Gentry, D.; Whinnery, J. T.; Ly, V. T.; Travers, S. V.; Sagaga, J.; Dahlgren, R. P.

2017-12-01

Microorganisms play a major role in our biosphere due to their ability to alter water, carbon and other geochemical cycles. Fog and low-level cloud water can play a major role in dispersing and supporting such microbial diversity. An ideal region to gather these microorganisms for characterization is the central coast of California, where dense fog is common. Fog captured from an unmanned aerial vehicle (UAV) at different altitudes will be analyzed to better understand the nature of microorganisms in the lower atmosphere and their potential geochemical impacts. The capture design consists of a square-meter hydrophobic mesh that hangs from a carbon fiber rod attached to a UAV. The DJI M600, a hexacopter, will be utilized as the transport for the payload, the passive impactor collection unit (PICU). The M600 will hover in a fog bank at altitudes between 10 and 100 m collecting water samples via the PICU. A computational flow dynamics (CFD) model will optimize the PICU's size, shape and placement for maximum capture efficiency and to avoid contamination from the UAV downwash. On board, there will also be an altitude, temperature and barometric pressure sensor whose output is logged to an SD card. A scale model of the PICU has been tested with several different types of hydrophobic meshes in a fog chamber at 90-95% humidity; polypropylene was found to capture the fog droplets most efficiently at a rate of .0042 g/cm2/hour. If the amount collected is proportional to the area of mesh, the estimated amount of water collected under optimal fog and flight conditions by the impactor is 21.3 g. If successful, this work will help identify the organisms living in the lower atmosphere as well as their potential geochemical impacts.

Composition of 298 Baptistina: Implications for the K/T impactor link

NASA Astrophysics Data System (ADS)

Reddy, V.; Emery, J. P.; Gaffey, M. J.; Bottke, W. F.; Cramer, A.; Kelley, M. S.

2009-01-01

Bottke et al. (2007) suggested that the breakup of the Baptistina asteroid family (BAF) 160+30 /-20 Myr ago produced an “asteroid shower” that increased by a factor of 2-3 the impact flux of kilometer-sized and larger asteroids striking the Earth over the last ~120 Myr. This result led them to propose that the impactor that produced the Cretaceous/Tertiary (K/T) mass extinction event 65 Myr ago also may have come from the BAF. This putative link was based both on collisional/dynamical modeling work and on physical evidence. For the latter, the available broadband color and spectroscopic data on BAF members indicate many are likely to be dark, low albedo asteroids. This is consistent with the carbonaceous chondrite-like nature of a 65 Myr old fossil meteorite (Kyte 1998)and with chromium from K/T boundary sediments with an isotopic signature similar to that from CM2 carbonaceous chondrites. To test elements of this scenario, we obtained near-IR and thermal IR spectroscopic data of asteroid 298 Baptistina using the NASA IRTF in order to determine surface mineralogy and estimate its albedo. We found that the asteroid has moderately strong absorption features due to the presence of olivine and pyroxene, and a moderately high albedo (~20%). These combined properties strongly suggest that the asteroid is more like an S-type rather than Xc-type (Mothé-Diniz et al. 2005). This weakens the case for 298 Baptistina being a CM2 carbonaceous chondrite and its link to the K/T impactor. We also observed several bright (V Mag. ≤16.8) BAF members to determine their composition.

Particle Size Distributions of Particulate Emissions from the Ferroalloy Industry Evaluated by Electrical Low Pressure Impactor (ELPI)

PubMed Central

Kero, Ida; Naess, Mari K.; Tranell, Gabriella

2015-01-01

The present article presents a comprehensive evaluation of the potential use of an Electrical Low Pressure Impactor (ELPI) in the ferroalloy industry with respect to indoor air quality and fugitive emission control. The ELPI was used to assess particulate emission properties, particularly of the fine particles (Dp ≤ 1 μm), which in turn may enable more satisfactory risk assessments for the indoor working conditions in the ferroalloy industry. An ELPI has been applied to characterize the fume in two different ferroalloy plants, one producing silicomanganese (SiMn) alloys and one producing ferrosilicon (FeSi) alloys. The impactor classifies the particles according to their aerodynamic diameter and gives real-time particle size distributions (PSD). The PSD based on both number and mass concentrations are shown and compared. Collected particles have also been analyzed by transmission and scanning electron microscopy with energy dispersive spectroscopy. From the ELPI classification, particle size distributions in the range 7 nm – 10 μm have been established for industrial SiMn and FeSi fumes. Due to the extremely low masses of the ultrafine particles, the number and mass concentration PSD are significantly different. The average aerodynamic diameters for the FeSi and the SiMn fume particles were 0.17 and 0.10 μm, respectively. Based on this work, the ELPI is identified as a valuable tool for the evaluation of airborne particulate matter in the indoor air of metallurgical production sites. The method is well suited for real-time assessment of morphology (particle shape), particle size, and particle size distribution of aerosols. PMID:25380385

An High Resolution Near-Earth Objects Population Enabling Next-Generation Search Strategies

NASA Technical Reports Server (NTRS)

Tricaico, Pasquale; Beshore, E. C.; Larson, S. M.; Boattini, A.; Williams, G. V.

2010-01-01

Over the past decade, the dedicated search for kilometer-size near-Earth objects (NEOs), potentially hazardous objects (PHOs), and potential Earth impactors has led to a boost in the rate of discoveries of these objects. The catalog of known NEOs is the fundamental ingredient used to develop a model for the NEOs population, either by assessing and correcting for the observational bias (Jedicke et al., 2002), or by evaluating the migration rates from the NEOs source regions (Bottke et al., 2002). The modeled NEOs population is a necessary tool used to track the progress in the search of large NEOs (Jedicke et al., 2003) and to try to predict the distribution of the ones still undiscovered, as well as to study the sky distribution of potential Earth impactors (Chesley & Spahr, 2004). We present a method to model the NEOs population in all six orbital elements, on a finely grained grid, allowing us the design and test of targeted and optimized search strategies. This method relies on the observational data routinely reported to the Minor Planet Center (MPC) by the Catalina Sky Survey (CSS) and by other active NEO surveys over the past decade, to determine on a nightly basis the efficiency in detecting moving objects as a function of observable quantities including apparent magnitude, rate of motion, airmass, and galactic latitude. The cumulative detection probability is then be computed for objects within a small range in orbital elements and absolute magnitude, and the comparison with the number of know NEOs within the same range allows us to model the population. When propagated to the present epoch and projected on the sky plane, this provides the distribution of the missing large NEOs, PHOs, and potential impactors.

Hypervelocity impact survivability experiments for carbonaceous impactors, part 2

NASA Technical Reports Server (NTRS)

Bunch, T. E.; Paque, Julie M.; Becker, Luann; Vedder, James F.; Erlichman, Jozef

1995-01-01

Hypervelocity impact experiments were performed to further test the survivability of carbonaceous impactors and to determine potential products that may have been synthesized during impact. Diamonds were launched by the Ames two-stage light gas gun into Al plate at velocities of 2.75 and 3.1 km sec(exp -1). FESEM imagery confirms that diamond fragments survived in both experiments. Earlier experiments found that diamonds were destroyed on impact above 4.3 km sec(exp -1). Thus, the upper stability limit for diamond on impact into Al, as determined from our experimental conditions, is between 3.1 and 4.3 km sec(exp -1). Particles of the carbonaceous chondrite Nogoya were also launched into Al at a velocity of 6.2 km sec (exp -1). Laser desorption (L (exp 2) MS) analyses of the impactor residues indicate that the lowest and highest mass polycyclic aromatic hydrocarbons (PAH's) were largely destroyed on impact; those of intermediate mass (202-220 amu) remained at the same level or increased in abundance. In addition, alkyl-substituted homologs of the most abundant pre-impacted PAH's were synthesized during impact. These results suggest that an unknown fraction of some organic compounds can survive low to moderate impact velocities and that synthesized products can be expected to form up to velocities of, at least, 6.5 km sec(exp -1). We also present examples of craters formed by a unique microparticle accelerator that could launch micron-sized particles of almost any coherent material at velocities up to approximately 15 km sec(exp -1). Many of the experiments have a direct bearing on the interpretation of LDEF craters.

Dynamical Sequestration of the Moon-Forming Impactor in Co-Orbital Resonance with Earth

NASA Astrophysics Data System (ADS)

Kortenkamp, Stephen J.; Hartmann, William J.

2015-11-01

Recent concerns about the giant impact hypothesis for the origin of the moon, and an associated “isotope crisis” are assuaged if the impactor was a local object that formed near Earth and the impact occurred relatively late. We investigated a scenario that may meet these criteria, with the moon-forming impactor originating in 1:1 co-orbital resonance with Earth. Using N-body numerical simulations we explored the dynamical consequences of placing Mars-mass companions in various co-orbital configurations with a proto-Earth having 90% of its current mass. We modeled configurations that include the four terrestrial planets as well as configurations that also include the four giant planets. In both the 4- and 8-planet models we found that a single additional Mars-mass companion typically remains a stable co-orbital of Earth for the entire 250 million year (Myr) duration of our simulations (33 of 34 simulations). In an effort to destabilize such a system we carried out an additional 45 simulations that included a second Mars-mass co-orbital companion. Even with two Mars-mass companions sharing Earth’s orbit most of these models (28) also remained stable for the entire 250 Myr duration of the simulations. Of the 17 two-companion models that eventually became unstable 12 impacts were observed between Earth and an escaping co-orbital companion. The average delay we observed for an impact of a Mars-mass companion with Earth was 101 Myr, and the longest delay was 221 Myr. Several of the stable simulations involved unusual 3-planet co-orbital configurations that could exhibit interesting observational signatures in plantetary transit surveys.

Formation of Apollo 16 impactites and the composition of late accreted material: Constraints from Os isotopes, highly siderophile elements and sulfur abundances

NASA Astrophysics Data System (ADS)

Gleißner, Philipp; Becker, Harry

2017-03-01

Fe-Ni metal-schreibersite-troilite intergrowths in Apollo 16 impact melt rocks and new highly siderophile element (HSE) and S abundance data indicate that millimeter-scale closed-system fractional crystallization processes during cooling of impactor-derived metal melt droplets in impact-melts are the main reason for compositional variations and strong differences in abundances and ratios of HSE in multiple aliquots from Apollo 16 impact melt rocks. Element ratios obtained from linear regression of such data are therefore prone to error, but weighted averages take into account full element budgets in the samples and thus represent a more accurate estimate of their impactor contributions. Modeling of solid metal-liquid metal partitioning in the Fe-Ni-S-P system and HSE patterns in impactites from different landing sites suggest that bulk compositions of ancient lunar impactites should be representative of impact melt compositions and that large-scale fractionation of the HSE by in situ segregation of solid metal or sulfide liquid in impact melt sheets most likely did not occur. The compositional record of lunar impactites indicates accretion of variable amounts of chondritic and non-chondritic impactor material and the mixing of these components during remelting of earlier ejecta deposits. The non-chondritic composition appears most prominently in some Apollo 16 impactites and is characterized by suprachondritic HSE/Ir ratios which increase from refractory to moderately volatile HSE and exhibit a characteristic enrichment of Ru relative to Pt. Large-scale fractional crystallization of solid metal from sulfur and phosphorous rich metallic melt with high P/S in planetesimal or embryo cores is currently the most likely process that may have produced these compositions. Similar materials or processes may have contributed to the HSE signature of the bulk silicate Earth (BSE).

NEA impactors: what direction to they come from?

NASA Astrophysics Data System (ADS)

Harris, Alan

2018-04-01

One might expect, if Earth-crossing NEAs are "thermalized" by prior close scattering encounters with the Earth, that final impact trajectories would be isotropic in direction. But orbital perturbations and other sources of entry and exit to the Earth-crossing zone are faster acting that thermalization, so the actual distribution of impacting orbits is quite anisotropic. I have studied impactor directions by adjusting the orbits of known Earth-crossing PHAs slightly to put them on intersecting orbits and then computed the direction of approach to the Earth. This arguably suffers from "looking under the lamp post", since NEAs are mostly discovered close to the opposition direction, so I also took the distribution of NEA orbits recently derived by Granvik and others and extracted, from a set of 100,000 synthetic orbits they provided, a subset of Earth-crossing PHAs and similarly adjusted them to be intersecting orbits. This should represent an unbiased set of orbits. I then weighted the impact directions by the individual Opik impact probability to obtain a distribution of impact directions weighted by actual impact probabilities. The result was that more than 40% of incoming trajectories clustered within 60 degrees of the opposition direction, and a similar fraction come from within 60 degrees of the solar direction. Thus ~80% of impactors come from only about 1/3 of the sky area, with almost none coming from 60-120 degrees solar elongation. The message is that existing ground-based surveys can hardly be improved upon by greater sky coverage with respect to detecting "death plunge" objects, and even space-based instruments offer very little improvement due to the very low solar elongation of most objects approaching from the solar direction.

Guided asteroid deflection by kinetic impact: Mapping keyholes to an asteroid's surface

NASA Astrophysics Data System (ADS)

Chesley, S.; Farnocchia, D.

2014-07-01

The kinetic impactor deflection approach is likely to be the optimal deflection strategy in most real-world cases, given the likelihood of decades of warning time provided by asteroid search programs and the probable small size of the next confirmed asteroid impact that would require deflection. However, despite its straightforward implementation, the kinetic impactor approach can have its effectiveness limited by the astrodynamics that govern the impactor spacecraft trajectory. First, the deflection from an impact is maximized when the asteroid is at perihelion, while an impact near perihelion can in some cases be energetically difficult to implement. Additionally, the asteroid change in velocity Δ V should aligned with the target's heliocentric velocity vector in order to maximize the deflection at a potential impact some years in the future. Thus the relative velocity should be aligned with or against the heliocentric velocity, which implies that the impactor and asteroid orbits should be tangent at the point of impact. However, for natural bodies such as meteorites colliding with the Earth, the relative velocity vectors tend to cluster near the sunward or anti- sunward directions, far from the desired direction. This is because there is generally a significant crossing angle between the orbits of the impactor and target and an impact at tangency is unusual. The point is that hitting the asteroid is not enough, but rather we desire to hit the asteroid at a point when the asteroid and spacecraft orbits are nearly tangent and when the asteroid is near perihelion. However, complicating the analysis is the fact that the impact of a spacecraft on an asteroid would create an ejecta plume that is roughly normal to the surface at the point of impact. This escaping ejecta provides additional momentum transfer that generally adds to the effectiveness of a kinetic deflection. The ratio β between the ejecta momentum and the total momentum (ejecta plus spacecraft) can range from around 1 for a porous, compressible body producing negligible ejecta, to 2 when the ejecta momentum matches the spacecraft momentum, and as high as 5--10 for rocky bodies that produce large, high-velocity ejecta fragments. If the impactor hits the centerpoint of a spherical asteroid the momentum of the escaping ejecta directly adds to the momentum of the impacting asteroid, but if the impact is oblique then the ejecta and spacecraft momenta are added to the asteroid in vector sum. This suggests the possibility that for a given intercept trajectory the asteroid deflection could include guidance by targeting an oblique impact that could steer the asteroid Δ V to a more optimal direction that is different from the relative velocity direction of the spacecraft. An oblique impact decreases the net Δ V magnitude, and yet could significantly increase the net deflection at the time of the threatening Earth encounter. We use asteroid (101955) Bennu, which is the target of the OSIRIS-REx asteroid sample return mission and which has a series of potential Earth impacts in the years from 2175--2196, as an example to demonstrate the effectiveness of the oblique impact. These future potential impacts will occur if the asteroid passes through one of a series of keyholes when the asteroid passes the Earth at roughly the lunar distance from the Earth in 2135. To study the Bennu deflection problem we simulate a hypervelocity spacecraft impact on Bennu in March 2021, after the OSIRIS-REx mission is complete. In our example, the spacecraft arrives from approximately the sunward direction, and targeting ahead or behind the center of the asteroid allows non-negligible transverse accelerations for modest values of β. A given impact location on the asteroid surface yields a given Δ V vector, and our approach starts by mapping the net Δ V components on the surface for an assumed value of β. Knowing the mapping from impact location to Δ V and also the mapping from Δ V to the future Earth miss distance allows us to map the surface locations where a spacecraft impact would lead to an Earth impact 150--200 years later. In effect, we are able to project Earth impact trajectories, or keyholes, onto the asteroid surface and, for a given value of β, we can target our impactor spacecraft for an area on the surface that avoids potential Earth impacts. Of course, at the present time we have little information on what is the appropriate value or range of values for β in the case of asteroid Bennu, or any other asteroid for that matter. However, if this information is made known, either through a precursor mission or better inferences as to its nature we can develop a distribution of β that can be used to better design an impact deflection strategy. Specifically, we can compute a map of Earth impact probability density on the surface of the asteroid based on an assumed probability density function for β. If we target the lowest impact probability density regions then we maximize the chance of a successful deflection. This approach has the potential to allow more efficient kinetic impactor deflection, and therefore the deflection of larger bodies than would otherwise be possible.

Mathematical modeling of filling of gas centrifuge cascade for nickel isotope separation by various feed flow rate

NASA Astrophysics Data System (ADS)

Ushakov, Anton; Orlov, Alexey; Sovach, Victor P.

2018-03-01

This article presents the results of research filling of gas centrifuge cascade for separation of the multicomponent isotope mixture with process gas by various feed flow rate. It has been used mathematical model of the nonstationary hydraulic and separation processes occurring in the gas centrifuge cascade. The research object is definition of the regularity transient of nickel isotopes into cascade during filling of the cascade. It is shown that isotope concentrations into cascade stages after its filling depend on variable parameters and are not equal to its concentration on initial isotope mixture (or feed flow of cascade). This assumption is used earlier any researchers for modeling such nonstationary process as set of steady-state concentration of isotopes into cascade. Article shows physical laws of isotope distribution into cascade stage after its filling. It's shown that varying each parameters of cascade (feed flow rate, feed stage number or cascade stage number) it is possible to change isotope concentration on output cascade flows (light or heavy fraction) for reduction of duration of further process to set of steady-state concentration of isotopes into cascade.

WHISTLER TURBULENCE FORWARD CASCADE VERSUS INVERSE CASCADE: THREE-DIMENSIONAL PARTICLE-IN-CELL SIMULATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Ouliang; Gary, S. Peter; Wang, Joseph, E-mail: ouliang@usc.edu, E-mail: pgary@lanl.gov, E-mail: josephjw@usc.edu

2015-02-20

We present the results of the first fully three-dimensional particle-in-cell simulations of decaying whistler turbulence in a magnetized, homogeneous, collisionless plasma in which both forward cascades to shorter wavelengths, and inverse cascades to longer wavelengths are allowed to proceed. For the electron beta β {sub e} = 0.10 initial value considered here, the early-time rate of inverse cascade is very much smaller than the rate of forward cascade, so that at late times the fluctuation energy in the regime of the inverse cascade is much weaker than that in the forward cascade regime. Similarly, the wavevector anisotropy in the inversemore » cascade regime is much weaker than that in the forward cascade regime.« less

Prevention of mother-to-child HIV transmission cascade in China: a systematic review and meta-analysis

PubMed Central

Zeng, Huan; Chow, Eric P F; Zhao, Yong; Wang, Yang; Tang, Maozhi; Li, Leyu; Tang, Xue; Liu, Xi; Zhong, Yi; Wang, Ailing; Lo, Ying-Ru; Zhang, Lei

2016-01-01

Introduction The Chinese government has invested US$140 million annually on prevention of mother-to-child transmission (PMTCT) of HIV. This study evaluates the programme by examining the improvements in programme coverage HIV testing and provision of antiviral drugs along the PMTCT cascade. Methods Data for PMTCT cascade indicators were collected through a comprehensive systematic review of published peer-reviewed English and Chinese literature during 2003–2011. Meta-analysis was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Results This study included 113 publications. HIV prevalence among pregnant women in China who accessed antenatal care (ANC) remained below 0.1% during the past decade. HIV testing coverage in pregnant women attending ANC and in HIV-exposed infants at 18 months significantly increased from 62.4% (95% CI 4.7% to 98.2%) and 22.1% (16.3% to 32.3%) in 2003 to 90.3% (88.4% to 91.8%) and 82.8% (66.9% to 99.5%) in 2011 respectively, whereas antiretroviral (ARV) prophylaxis uptake increased from 35.2% (12.2% to 47.3%) and 26.9% (24.3% to 28.9%) to 86.2% (53.2% to 97.2%) and 90.3% (85.5% to 93.7%). HIV vertical transmission rate substantially decreased from 31.8% (25.7% to 38.6%) prior to the programme to 2.3% (1.4% to 3.8%) in 2011. During 2003–2011, among 25 312 (23 995–26 644) infants born to HIV-positive mothers who received ARV prophylaxis, 975 (564–1395) were diagnosed with HIV, corresponding to an average transmission rate of 3.9% (3.2% to 4.6%). However, while including transmissions among HIV-positive pregnant women who were lost along the cascade, the average transmission rate during 2003–2011 was 17.4% (15.8% to 19.0%). Conclusions PMTCT programmes have reduced HIV mother-to-child transmission in China. Further improvements in the continuum of care remain essential in realising the full potential of the programme. PMID:25935929

Mount Saint Helens aerosol evolution

NASA Technical Reports Server (NTRS)

Oberbeck, V. R.; Farlow, N. H.; Snetsinger, K. G.; Ferry, G. V.; Fong, W.; Hayes, D. M.

1982-01-01

Stratospheric aerosol samples were collected using a wire impactor during the year following the eruption of Mt. St. Helens. Analysis of samples shows that aerosol volume increased for 6 months due to gas-to-particle conversion and then decreased to background levels in the following 6 months.

Geochemical Constraints on the Size of the Moon — Forming Giant Impact

NASA Astrophysics Data System (ADS)

Piet, H.; Badro, J.; Gillet, P.

2018-05-01

We use the partitioning of siderophile trace elements to model the geochemical influence of the Moon-forming giant impact on Earth’s mantle during core formation. We find the size of the impactor to be 15% of Earth mass or smaller.

Centrifuge impact cratering experiments: Scaling laws for non-porous targets

NASA Technical Reports Server (NTRS)

Schmidt, Robert M.

1987-01-01

A geotechnical centrifuge was used to investigate large body impacts onto planetary surfaces. At elevated gravity, it is possible to match various dimensionless similarity parameters which were shown to govern large scale impacts. Observations of crater growth and target flow fields have provided detailed and critical tests of a complete and unified scaling theory for impact cratering. Scaling estimates were determined for nonporous targets. Scaling estimates for large scale cratering in rock proposed previously by others have assumed that the crater radius is proportional to powers of the impactor energy and gravity, with no additional dependence on impact velocity. The size scaling laws determined from ongoing centrifuge experiments differ from earlier ones in three respects. First, a distinct dependence of impact velocity is recognized, even for constant impactor energy. Second, the present energy exponent for low porosity targets, like competent rock, is lower than earlier estimates. Third, the gravity exponent is recognized here as being related to both the energy and the velocity exponents.

Towards reducing impact-induced brain injury: lessons from a computational study of army and football helmet pads.

PubMed

Moss, William C; King, Michael J; Blackman, Eric G

2014-01-01

We use computational simulations to compare the impact response of different football and U.S. Army helmet pad materials. We conduct experiments to characterise the material response of different helmet pads. We simulate experimental helmet impact tests performed by the U.S. Army to validate our methods. We then simulate a cylindrical impactor striking different pads. The acceleration history of the impactor is used to calculate the head injury criterion for each pad. We conduct sensitivity studies exploring the effects of pad composition, geometry and material stiffness. We find that (1) the football pad materials do not outperform the currently used military pad material in militarily relevant impact scenarios; (2) optimal material properties for a pad depend on impact energy and (3) thicker pads perform better at all velocities. Although we considered only the isolated response of pad materials, not entire helmet systems, our analysis suggests that by using larger helmet shells with correspondingly thicker pads, impact-induced traumatic brain injury may be reduced.

Structural changes in shock compressed silicon observed using time-resolved x-ray diffraction at the Dynamic Compression Sector

NASA Astrophysics Data System (ADS)

Turneaure, Stefan; Zdanowicz, E.; Sinclair, N.; Graber, T.; Gupta, Y. M.

2015-06-01

Structural changes in shock compressed silicon were observed directly using time-resolved x-ray diffraction (XRD) measurements at the Dynamic Compression Sector at the Advanced Photon Source. The silicon samples were impacted by polycarbonate impactors accelerated to velocities greater than 5 km/s using a two-stage light gas gun resulting in impact stresses of about 25 GPa. The 23.5 keV synchrotron x-ray beam passed through the polycarbonate impactor, the silicon sample, and an x-ray window (polycarbonate or LiF) at an angle of 30 degrees relative to the impact plane. Four XRD frames (~ 100 ps snapshots) were obtained with 153.4 ns between frames near the time of impact. The XRD measurements indicate that in the peak shocked state, the silicon samples completely transformed to a high-pressure phase. XRD results for both shocked polycrystalline silicon and single crystal silicon will be presented and compared. Work supported by DOE/NNSA.

Spacecraft studies of Phobos and Mars

NASA Technical Reports Server (NTRS)

Murray, Bruce C.

1990-01-01

Utilizing the Termoskan data set of the Phobos '88 mission we have recognized a new feature on Mars: Ejecta blanket Distinct In the THermal infrared (EDITH). Virtually all of the more than one hundred of these features discovered in the Termoskan data are located on the plains near Valles Manneris. EDITH's have a startlingly clear dependence upon terrains of Hesperian age, implying a spatial or temporal dependence on Hesperian terrains. Almost no thermally distinct ejecta blankets are associated with any of the thousands of craters within the data set that occur on the older Noachian units. EDITH's also do not appear on the portions of the younger Tharsis Amazonian units seen in the data. The Hesperian terrain dependence cannot be explained by either atmospheric or impactor variations; Noachian and Hesperian terrains must have experienced identical atmospheric and impactor conditions during Hesperian times. Thermally distinct eject a blankets therefore reflect target material differences and/or secondary modification processes. A further discussion of EIDTH's is presented.

Cometary Dust Characteristics: Comparison of Stardust Craters with Laboratory Impacts

NASA Technical Reports Server (NTRS)

Kearsley, A. T.; Burchell, M. J.; Graham, G. A.; Horz, F.; Wozniakiewicz, P. A.; Cole, M. J.

2007-01-01

Aluminium foils exposed to impact during the passage of the Stardust spacecraft through the coma of comet Wild 2 have preserved a record of a wide range of dust particle sizes. The encounter velocity and dust incidence direction are well constrained and can be simulated by laboratory shots. A crater size calibration programme based upon buckshot firings of tightly constrained sizes (monodispersive) of glass, polymer and metal beads has yielded a suite of scaling factors for interpretation of the original impacting grain dimensions. We have now extended our study to include recognition of particle density for better matching of crater to impactor diameter. A novel application of stereometric crater shape measurement, using paired scanning electron microscope (SEM) images has shown that impactors of differing density yield different crater depth/diameter ratios. Comparison of the three-dimensional gross morphology of our experimental craters with those from Stardust reveals that most of the larger Stardust impacts were produced by grains of low internal porosity.

[Sampling methods for PM2.5 from stationary sources: a review].

PubMed

Jiang, Jing-Kun; Deng, Jian-Guo; Li, Zhen; Li, Xing-Hua; Duan, Lei; Hao, Ji-Ming

2014-05-01

The new China national ambient air quality standard has been published in 2012 and will be implemented in 2016. To meet the requirements in this new standard, monitoring and controlling PM2,,5 emission from stationary sources are very important. However, so far there is no national standard method on sampling PM2.5 from stationary sources. Different sampling methods for PM2.5 from stationary sources and relevant international standards were reviewed in this study. It includes the methods for PM2.5 sampling in flue gas and the methods for PM2.5 sampling after dilution. Both advantages and disadvantages of these sampling methods were discussed. For environmental management, the method for PM2.5 sampling in flue gas such as impactor and virtual impactor was suggested as a standard to determine filterable PM2.5. To evaluate environmental and health effects of PM2.5 from stationary sources, standard dilution method for sampling of total PM2.5 should be established.

The effect of impact angle on craters formed by hypervelocity particles

NASA Technical Reports Server (NTRS)

Hill, David C.; Rose, M. Frank; Best, Steve R.; Crumpler, Michael S.; Crawford, Gary D.; Zee, Ralph H.-C.; Bozack, Michael J.

1995-01-01

The Space Power Institute (SPI) at Auburn University has conducted experiments on the effects of impact angle on crater morphology and impactor residue retention for hypervelocity impacts. Copper target plates were set at angles of 30 deg, 45 deg, 60 deg, and 75 deg from the particle flight path. For the 30 deg and 45 deg impacts, in the velocity regime greater than 8 km s(exp -1) the resultant craters are almost identical to normal incidence impacts. The only difference found was in the apparent distribution of particle residue within the crater, and further research is needed to verify this. The 60 deg and 75 deg impacts showed marked differences in crater symmetry, crater lip shape, and particle residue distribution in the same velocity regime. Impactor residue shock fractionation effects have been quantified in first-order. It is concluded that a combination of analysis techniques can yield further information on impact velocity, direction, and angle of incidence.

Lunar-forming impacts: processes and alternatives

PubMed Central

Canup, R. M.

2014-01-01

The formation of a protolunar disc by a giant impact with the early Earth is discussed, focusing on two classes of impacts: (i) canonical impacts, in which a Mars-sized impactor produces a planet–disc system whose angular momentum is comparable to that in the current Earth and Moon, and (ii) high-angular-momentum impacts, which produce a system whose angular momentum is approximately a factor of 2 larger than that in the current Earth and Moon. In (i), the disc originates primarily from impactor-derived material and thus is expected to have an initial composition distinct from that of the Earth's mantle. In (ii), a hotter, more compact initial disc is produced with a silicate composition that can be nearly identical to that of the silicate Earth. Both scenarios require subsequent processes for consistency with the current Earth and Moon: disc–planet compositional equilibration in the case of (i), or large-scale angular momentum loss during capture of the newly formed Moon into the evection resonance with the Sun in the case of (ii). PMID:25114302

Copper Hugoniot measurements to 2.8 TPa on Z.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Furnish, Michael D.; Haill, Thomas A

We conducted three Hugoniot and release experiments on copper on the Z machine at Hugoniot stress levels of 0.34 and 2.6 TPa, using two-layer copper/aluminum impactors travelling at 8 and 27 km/s and Z-quartz windows. Velocity histories were recorded for 4 samples of different thicknesses and 5 locations on the flyer plate (3 and 4 for the first two experiments). On-sample measurements provided Hugoniot points (via transit time) and partial release states (via Z-quartz wavespeed). Fabrication of the impactor required thick plating and several diamond-machining steps. The lower-pressure test was planned as a 2.5 TPa test, but a failure onmore » the Z machine degraded its performance; however, these results corroborated earlier Cu data in the same stress region. The second test suffered from significant flyer plate bowing, but the third did not. The Hugoniot data are compared with the APtshuler/Nellis nuclear-driven data, other data from Z and elsewhere, and representative Sesame models.« less

Use of a New Portable Instrumented Impactor on the NASA Composite Crew Module Damage Tolerance Program

NASA Technical Reports Server (NTRS)

Jackson, Wade C.; Polis, Daniel L.

2014-01-01

Damage tolerance performance is critical to composite structures because surface impacts at relatively low energies may result in a significant strength loss. For certification, damage tolerance criteria require aerospace vehicles to meet design loads while containing damage at critical locations. Data from standard small coupon testing are difficult to apply to larger more complex structures. Due to the complexity of predicting both the impact damage and the residual properties, damage tolerance is demonstrated primarily by testing. A portable, spring-propelled, impact device was developed which allows the impact damage response to be investigated on large specimens, full-scale components, or entire vehicles. During impact, both the force history and projectile velocity are captured. The device was successfully used to demonstrate the damage tolerance performance of the NASA Composite Crew Module. The impactor was used to impact 18 different design features at impact energies up to 35 J. Detailed examples of these results are presented, showing impact force histories, damage inspection results, and response to loading.

Precipitation and Hydrology Experiment Counter-Flow Spectrometer and Impactor Field Campaign Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poellot, Michael

The U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility Aerial Facility (ARM AAF) counter-flow spectrometer and impactor (CSI) probe was flown on the University of North Dakota Cessna Citation research aircraft during the Integrated Precipitation and Hydrology Experiment (IPHEX). The field campaign took place during May and June of 2014 over North Carolina and its coastal waters as part of a National Aeronautics and Space Administration (NASA) Global Precipitation Measurement validation campaign. The CSI was added to the Citation instrument suite to support the involvement of Jay Mace through the NASA Advanced Composition Explorer (ACE) satellitemore » program and flights of the NASA ER-2 aircraft, which is a civilian version of the Air Force’s U2-S reconnaissance platform. The ACE program funded extra ER-2 flights to focus on clouds that are weakly precipitating, which are also of interest to the Atmospheric System Research program sponsored by DOE.« less